Dissertations / Theses on the topic 'Hydrogen-ion concentration'
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Nyberg, Lindborg Kristina. "Phagolysosomal pH measurements in alveolar macrophages /." Stockholm, 2000. http://diss.kib.ki.se/2000/91-628-4512-8/.
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Koort, Eve. "Uncertainty estimation of potentiometrically measured pH and pK[subscript a] values /." Online version, 2006. http://dspace.utlib.ee/dspace/bitstream/10062/599/5/koorteve.pdf.
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Huang, Ming-Chieh. "Silicon microfabricated device for non-sheath-flow cytometer-based chemical analysis and microchannel flow sensing /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/5870.
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CORDARO, RICHARD BRIAN. "ELECTRON IMPACT DISSOCIATIVE IONIZATION OF HYDROGEN, WATER, AND HYDROGEN SULFIDE." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188028.
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The dissociative ionization by electron impact of H₂, H₂O, and H₂S was investigated between the electron impact energies of 20 and 45 eV. Protons were the detected fragments, and a time-of-flight method was used to measure the proton kinetic energies. By also measuring the thresholds for the production of discrete energy groups of protons, it was possible to determine the dissociation limits and kinetic energy distributions for individual electronic states. It was found that autoionizing states that lead to dissociation were the major contributors of proton fragments for all of the molecules investigated. Some of the measurements are tabulated in the following table. (UNFORMATTED TABLE FOLLOWS) Molecule Threshold Dissociation Probable Probable (eV) limit (eV) state fragments H₂ 24.5±1.0 18.0±1.0 Q₁ ¹Σ(g)⁺ H⁺, H(1S) 30.5±1.0 18.0±1.0 Q₁ ¹Πᵤ H⁺, H(1S) 36.5±1.0 -- ²Πᵤ H⁺, H(2P) H₂O 24.5±1.0 19.5±1.0 -- H⁺, OH (X²Π) 29.5±1.0 23.0±1.0 -- H⁺,O(³P),H(1S) H₂S 25.5±1.0 18.0±1.0 -- H⁺, HS (X²Π) 32.0±1.0 -- -- H⁺, . . . 42.0±1.0 -- -- H⁺, . . . (TABLE ENDS)
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Mo, Fong-ming. "The role of intracellular pH in the control of adenosine output from oxidative skeletal muscle in-vivo and in-vitro /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B17310696.
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CHO, HYUCK. "COINCIDENCE DETECTION OF PROTONS AND METASTABLE HYDROGEN ATOMS FROM DISSOCIATIVE IONIZATION OF MOLECULAR HYDROGEN BY ELECTRON IMPACT (TIME-OF-FLIGHT)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188027.
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A coincidence has been observed between H(2S) and H⁺ fragments resulting from the bombardment of H₂ with 100 eV electrons. A significant source of this coincidence is believed to be the 2sσ(g) state of H₂⁺. The time-of-flight (TOF) distribution of H(2S) fragments from the 2sσ(g) state was measured and converted to the kinetic energy distribution from which the potential energy of the 2sσ(g) state in the Franck-Condon region was constructed. The result is in good agreement with a published calculation.
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CASTLE, KENNETH ROBERT. "ABSOLUTE RADIOMETRIC CALIBRATION OF A SPECTROPOLARIMETER." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188026.
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Two identical instruments have been developed for use in the field to make radiometric measurements. They have been described as spectropolarimeters because of their ability to make polarization measurements in narrow spectral passbands. They have been used as part of a NASA sponsored project to monitor the spectral and temporal response of the thematic mapper satellites. These satellites allow many natural and man-tended resources to be monitored over years of time, thus allowing their use to be planned for in the future. The dissertation discusses the design, fabrication, testing and absolute radiometric calibration of these spectropolarimeter instruments. The outstanding feature of these instruments are that they have been calibrated absolutely, for radiance measurements, to an accuracy of 2% - 3%, in the range of 400 nm to 1040 nm over selected spectral passbands. Previously, field measurements were considered good if they had an absolute accuracy of 10%, implying that the present accuracies are advancing the state-of-the-art for field instrument calibrations. These improved accuracies are the result of using two recently developed calibration standards, both of which use detector based methods. These standards are the Electrically Calibrated Pyroelectric Radiometer (ECPR), and the QED-100 quad detector. The end of the dissertation discusses the attempts made to verify that the accuracies claimed are indeed valid, and it is the author's belief that these accuracies have been verified completely.
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巫放明 and Fong-ming Mo. "The role of intracellular pH in the control of adenosine output from oxidative skeletal muscle in-vivo and in-vitro." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31235190.
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Wang, Guo-Ji 1953. "Effect of pH on the structure and function of La Crosse virus." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277186.
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The La Crosse (LAC) virus is a member of the California encephalitis group of bunyaviridae (Porterfield et al., 1975 and 1976). It is one of an envelope virus and this virus under acidic conditions (below pH 6.3) has been demonstrated to result in cell-to-cell fusion (Gonzalez-Scarano, 1984). The LAC virus is also capable of forming virus-to-virus fusion particles. The focus of this thesis is the analysis of the structure and function of this virus-to-virus fusion by cryo-electron microscopy at different pH and temperatures. The results of this study provide the basis for further study of the structure and function of the LAC virus. The virus-to-virus fusion event shows a dependence on both pH and temperature. The frequency of the fusion event increases with an elevation in temperature (in the range 4 to 37°C) and with a decrease in pH from 7.3 to 5.4. The process of virus-to-virus fusion gives rise to the formation budding to a chain of fused viruses.
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Meng, Yiyu. "Nitrite oxidising bacteria in soil : examination of the interactions with ammonia oxidisers and the influence of pH on their diversity and distribution." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=231853.
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Nitrification is a central part of the nitrogen cycle, whereby the most reduced form, ammonia, is converted to the most oxidised form, nitrate via nitrite. The first step is performed by ammonia oxidising bacteria (AOB) and archaea (AOA), with the second step performed by nitrite oxidising bacteria (NOB). Although both groups are closely associated in nature, ammonia oxidisers have received more attention compared to NOB as ammonia oxidation is considered the rate-limiting step. Nitrobacter and Nitrospira are two important groups of soil NOB. To determine whether there are specific associations of AOA or AOB with certain NOB, the effect of organic and inorganic ammonia sources was tested by adding glutamate or ammonium sulphate to soil together with either 5% 12CO2 or 13CO2 to determined autotrophic growth by DNA-SIP. The results demonstrated that while the various ammonia and nitrite oxidisers responded differently, there was no direct evidence of specific coupled interactions. The effects of soil pH on Nitrobacter and Nitrospira was then investigated in a long-term pH gradient in an agricultural field. The results demonstrated that Nitrospira abundance was lower in acidic soils, whereas Nitrobacter abundance remained equally or more abundant. pH also influenced the relative distribution of Nitrobacter and Nitrospira populations, with distinct community structures at both high and low pH. The interaction of AOA and NOB was further investigated in a co-culture experiment, and demonstrated that the removal of nitrite and free nitrous acid NOB enhanced both rates and amounts of ammonia oxidised, indicating that in acidic environments these relationships may be particularly critical. Finally, the use of the compound PTIO was investigated for potential use in elucidating specific relationships between AOA and NOB. Results demonstrated a lack of specificity for the target group, and was unstable in soil, and therefore its use in soil should proceed with caution.
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Bischoff, Timothy William. "Ammonium production by Bipolaris maydis race T on L-asparagine and its relationship to pH /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487265555440415.
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Wilcox, Jeffrey Kendall. "Influence of pH on zinc adsorption by kaolinite, montmorillonite, and Londonderry clay." Thesis, The University of Sydney, 1994. https://hdl.handle.net/2123/26746.
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The adsorption of zinc ions as a function of pH and total dissolved metal concentration was experimentally investigated for three types of clays (kaolinite. montmonllonite. and Londonderry). The results indicate increases in adsorption of the zinc ions occurs with increases in pH for each of the three clays. Langmuir and Freundlich isotherms were created for each of the clay types.
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McMillan, Duncan George Glenn, and n/a. "Proton and iron capture mechanisms of Bacillus sp. strain TA2.A1 at alkaline pH values." University of Otago. Department of Microbiology & Immunology, 2008. http://adt.otago.ac.nz./public/adt-NZDU20081104.090840.
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The thermoalkaliphilic Bacillus sp. strain TA2.A1 was able to grow in pH-controlled batch culture containing a fermentable growth substrate (i.e. sucrose) from pH 7.5 to 10.0 with no significant change in specific growth rate, suggesting that this bacterium is a facultative alkaliphile. However, when strain TA2.A1 was grown on non-fermentable carbon sources like succinate, no growth was observed until the external pH was > 9.0, suggesting this bacterium is an obligate alkaliphile. Growth on succinate at pH 9.5 was sensitive to both carbonyl cyanide m-chlorophenylhydrazone (CCCP) and monensin revealing that both the proton and sodium motive force ([Delta][mu][H⁺] and [Delta][mu][Na⁺], respectively) were obligate requirements for growth at alkaline pH values. Transport of succinate was driven by a chemical gradient of Na⁺ ([Delta]pNa⁺) that was strictly coupled to [Delta][Psi]. A single transport system was detected for the uptake of succinate, with an apparent K[m] of 19 [mu]M and V[max] of 0.45 nmol succinate/min/mg protein. Succinate transport was pH-dependent, and showed optimal activity at pH values greater than 8.5. Other C₄-dicarboxylates (e.g. malate, fumarate) inhibited the uptake of succinate suggesting that the permease was general for other C₄-dicarboxylates.
Cytochrome content, succinate dehydrogenase oxidoreductase, and F₁F₀-ATPase activities were lower in membranes from strain TA2.A1 cells grown at pH 7.5 compared to those cultured at 9.5. These data suggest that oxidative phosphorylation-linked processes are down-regulated at neutral pH values, an observation that mirrored oxygen consumption profiles of strain TA2.A1 in whole cells. To study this phenomenon at a molecular level, we measured ATP synthesis by the F₁F₀-ATP synthase from strain TA2.A1 as a function of pH. The strain TA2.A1 F₁F₀-ATP synthase had a pH optimum for ATP synthesis of 9.0-9.5, and significantly lower rates of ATP synthesis observed below pH 9.0. Analysis of the atp operon from the thermoalkaliphilic Bacillus sp. strain TA2.A1 and comparison with other atp operons from alkaliphilic bacteria reveals the presence of a conserved lysine residue at position 180 (Bacillus sp. strain TA2.A1 numbering) within the a subunit of these F₁F₀-ATP synthases. We hypothesize that the basic nature of this residue is ideally suited to capture protons from the bulk phase at high pH. To test this hypothesis, a heterologous expression system for the ATP synthase from Bacillus sp. TA2.A1 (TA2F₁F₀) was developed in Escherichia coli DK8 ([Delta]atp). Amino acid substitutions were made in the a subunit of TA2F₁F₀ at position 180. Lysine (aK180) was substituted for the basic residues histidine (aK180H) or arginine (aK180R), and the uncharged residue glycine (aK180G). ATP synthesis experiments were performed in ADP plus P[i]-loaded right-side out membrane vesicles energized by ascorbate-phenazine methosulfate. When these enzyme complexes were examined for their ability to perform ATP synthesis over the pH range from 7.0 to 10.0, TA2F₁F₀ and aK180R showed a similar pH profile having optimum ATP synthesis rates at pH 9.0 to 9.5 with no measurable ATP synthesis at pH 7.5. Conversely, aK180H and aK180G showed maximal ATP synthesis at pH�s 8.0 and 7.5, respectively. ATP synthesis under these conditions for all enzyme forms was sensitive to DCCD. These data strongly imply that amino acid residue K180 is a specific adaptation within the a subunit of TA2F₁F₀ to facilitate proton capture at high pH. At pH values near the pK[a] of K180, the trapped protons readily dissociate to reach the subunit c binding sites but this dissociation is impeded at neutral pH values causing either a blocking of the proposed H⁺ channel and/or mechanism of proton translocation, and hence ATP synthesis is inhibited.
The mechanisms where by alkaliphilic bacteria obtain iron remains unknown. Growth of strain TA2.A1 at pH 9.5 in the presence of the artificial iron chelators ethylenediamine O-hydroxyphenylacetic acid (EDDHA) and 2�2� dipyridal revealed that iron is an important requirement for aerobic growth at alkaline pH values. Furthermore, biochemical analysis showed that Bacillus alcalophilus and Bacillus pseudofirmus both synthesized orange catecholate siderophores, whilst Bacillus halodurans synthesized a hydroxamate siderophore. These tests showed that strain TA2.A1 synthesized both orange catecholate and hydroxamate siderophore/s. Attempts to purify the catecholate were unsuccessful. No homologues of previously identified non-ribosomal peptide synthase (NRPS) genes in Bacillus subtilis and B.halodurans were detected in the genome of strain TA2.A1 using both PCR and Southern hybridization using known non-ribosomal peptide synthase genes.
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Barman, Dipti Narayan. "pH sensitive fluorescent sensors." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4972.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 3, 2009) Includes bibliographical references.
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Page, Ray Dean. "Characterization of H+ Excretion in a Model Renal Epithelium." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc332842/.
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The cellular regulation of acidification and intracellular ph (pHi) was studied in the integument of Rana pipiens, a model renal epithelium. Acidification was enhanced by : (1) chronic metabolic acidosis, (2) high salinity adaptation, and (3) ibuprofen treatment.
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Ye, Xuemin. "The effect of water pH on swimming performance, blood pH, red cell pH, ion concentrations and catecholamine concentrations in plasma, and gill potential in rainbow trout (Salmo gairdneri)." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26676.
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The effect of transferring fish from water at pH 7.0 to either more acid or more alkaline conditions was to reduce the maximum critical velocity of the fish. In water of pH 4.0, 5.0, and 10.0, the maximum critical velocity was only 54.5%, 66.5%, and 61% respectively of that recorded for fish in the water of pH 7.0. Thus, both acid and alkaline conditions in the water reduce the aerobic swimming capacity of trout.
Exposure to acid conditions increased mucus secretion and this was associated with an increase in coughing and breathing frequency in resting fish. Coughing rate increased from 41/hr to 592/hr; and respiration frequency increased from 81/min to 104/min when fish were transferred from water at pH 7.0 to water at pH 4.0.
In comparing fish exposed to acid and alkaline waters, the results indicates that fish have a greater capacity to regulate blood pH in acid than in alkaline conditions.
The gill potential was strongly dependent on water pH, being negative in neutral water, but positive in acid water and more negative in alkaline solution. Catecholamine levels increased significantly during acid exposure, but were not altered during alkaline exposure. The increasing catecholamine levels appeared at different time periods in different fish during acid exposure and seemed to be associated with the death of the fish.
Na⁺ and C1⁻ ion concentrations in plasma decreased significantly after 24hrs of acid exposure, but did not change significantly in alkaline water. This may indicate that ionoregulatory disturbance in plasma is one of the reasons for the decrease in the maximum critical velocity in acid water, but not in alkaline water.Science, Faculty of
Zoology, Department of
Graduate
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Vinnakota, Kalyan Chakravarthy. "pH dynamics, glycogenolysis and phosphoenergetics in isolated cell free reconstituted systems and in mouse skeletal muscle /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8034.
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Heyes, Colin D. "Effects of pH, cations and lipids on the structure, stability and function of bacteriorhodopsin." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/30754.
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Shorrock, Susan M. "The exploration of tissue pH and its relationship to bacterial contamination." Link to electronic version, 2000. http://www.wpi.edu/Pubs/ETD/Available/etd-0426100-172003/.
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Vasconcellos, Andréa Araújo de 1986. "Evaluation of extracellular matrix and structure of Candida albicans biofilms developed at different pH conditions = Avaliação da matriz extracelular e da estrutura de biofilmes de Candida albicans desenvolvidos em diferentes condições de pH." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290230.
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Orientador: Wander José da SilvaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: A colonização da prótese dental por Candida albicans pode contribuir para o desenvolvimento de candidose associada ao seu uso. As variações de pH que ocorrem no biofilme formado sobre a prótese dental podem influenciar a quantidade de matriz extracelular e a estrutura do biofilme de C. albicans. Entretanto, não está claro como o pH pode interferir na matriz extracelular e em determinados parâmetros estruturais nos biofilmes de C. albicans. O objetivo neste estudo foi avaliar a influência do pH na quantidade de matriz extracelular e na estrutura de biofilmes de C. albicans. Discos de resina à base de poli (metilmetacrilato) com a rugosidade de superfície padronizada foram utilizados como substrato para a formação dos biofilmes. Os discos foram cobertos por uma película de saliva e biofilmes de C. albicans ATCC 90028 foram desenvolvidos em meio de cultura RPMI 1640 tamponado em diferentes valores de pH (4,0, 5,5 e 7,0) por 48 horas como grupos experimentais, e meio de cultura sem o tamponamento (pH inicial de 7,4) como grupo controle. O número de células viáveis foi quantificado por diluição seriada, e a quantidade de matriz de polissacarídeos foi analisada pelo método fenol-sulfúrico (n = 9). As características morfológicas dos biofilmes foram observadas por meio de microscopia eletrônica de varredura e por microscopia confocal (n = 3). Os resultados foram submetidos à análise de variância com um fator, seguido pelo teste de Tukey, com nível de significância de 5%. Observou-se aumento significativo no número de células viáveis nos biofilmes desenvolvidos em pH 4,0 e 5,5 (p < 0,001). A quantidade de polissacarídeos foi maior em pH 5,5, seguida por biofilmes desenvolvidos em pH 4,0 (p < 0,05). As imagens obtidas por microscopia eletrônica de varredura e por microscopia confocal mostram maior formação de hifas pelos biofilmes quando desenvolvidos em pH 7,0 e no grupo controle. Pode ser concluído que condições de pH ácidos influenciaram a formação de biofilmes com o maior número de células viáveis e, consequentemente, maior quantidade de matriz extracelular. Além disso, o pH afetou consideravelmente a morfologia dos biofilmes de C. albicans
Abstract: The colonization of dental prosthesis by Candida albicans may contribute to the development of Candida-associated denture stomatitis. The pH changes that occur in the biofilm developed over the dental prosthesis may influence the amount of extracellular matrix and the structure of C. albicans biofilms. However, it is not clear how the pH could interfere in the extracellular matrix and specifically structural parameters of C. albicans biofilms. The object of this study was to evaluate the influence of environmental pH on the amount of extracellular matrix and structure in C. albicans biofilms. Poly (methylmethacrylate) resin discs with surface roughness standardized were used as substrate for biofilm formation. The discs were covered by the salivary pellicle, and C. albicans ATCC 90028 biofilms were developed in RPMI 1640 culture medium buffered at different pH values (4.0, 5.5 and 7.0) for 48 hours as experimental groups, and unbuffered culture medium (initial pH of 7.4) as control. The number of viable cells was quantified by serial dilution, and the amount of polysaccharide matrix was analyzed by phenol sulfuric method (n = 9). The morphological characteristics of biofilms were observed by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) (n = 3). Data were analyzed by one-way ANOVA, followed by Tukey's test, with significance set at 5%. It was observed a significant increase in the number of viable cells in biofilms developed at pH 4.0 and 5.5 (p < 0.001). The amount of polysaccharides was higher at pH 5.5, followed by biofilms developed at pH 4.0 (p < 0.05). The images obtained by SEM and CLSM showed higher hyphae formation by biofilms developed at pH 7.0 and in the control group. It can be concluded that acidic pH conditions influenced the formation of C. albicans biofilms, with higher viable cells and, consequently, higher amount of extracellular matrix. Furthermore, the pH significantly affected the morphology of C. albicans biofilms
Doutorado
Protese Dental
Doutora em Clínica Odontológica
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Roulston, Dallas Peter. "An investigation of optical methods for the mapping of microgradients of hydrogen-ion concentration within dental biofilms." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1565417/.
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The oral cavity is the most complex and accessible microbial ecosystem in the human body. It is the entrance to the respiratory and gastrointestinal tracts and, as such is exposed to unique environmental constraints. The human mouth is home to a myriad of microorganisms, many of which are exclusively found in this unique habitat. These microbial inhabitants can establish themselves and thrive in this environment by attaching to the various surfaces of the oral cavity. Following attachment, they form three-dimensional, complex and highly-integrated microbial communities. Despite their complexity and natural fluctuations in environmental parameters, in health, these communities remain relatively stable over time. This stability is termed microbial homeostasis. Disruption of the microbial homeostasis occurs as a result of regular or prolonged challenges in the form of an altered environment. These disruptions favour a shift in the microbial populations, suppressing the metabolism of the beneficial inhabitants and allowing unfavourable microorganisms to thrive in the lack of competition. This change in the oral microbiota facilitates the progression from oral health to disease. Despite continuing research and development in preventative measures dental caries, characterised by localised dissolution of the dental hard tissues, remain one of the most prevalent disorders affecting man today. This decay occurs as a result of strong organic acids produced by the microbiota within dental plaque following exposure to fermentable carbohydrates. Furthermore, prolonged and regular exposure to acids suppresses the growth of 'beneficial' bacteria allowing acidogenic, aciduric microorganisms, such as Streptococcus mutans and lactobacilli to thrive in the lack of competition. The presence of these acidogenic microorganisms causes an increase in acid production and an increase in the duration of exposure to those acids. Although rarely life-threatening, they create an enormous economic burden to healthcare providers worldwide and cause significant physical and social impact on those affected, including diet, communication and self-esteem. Greater understanding is required to appreciate the dynamic relationship that exists between the environment, the microbiota and the host. To gain a greater understanding of how the microbial ecology is affected, it is necessary to be able to determine how pH changes during and following fermentation and the effect these perturbations have upon the microbial community. At present, the most commonly employed methods include the use of microelectrodes, whether through insertion into laboratory grown biofilm or incorporated within in vivo prosthetics devices. These methods are not without their drawbacks. In the act of measurement, microelectrodes are inserted into the biofilm resulting in, at least partial, disruption of the biofilm and this may have a detrimental effect on the results. In vivo prosthetics provides measurement at the biofilm interfaces and in physiological conditions, however almost certainly require partially dentate individuals and are difficult to use. Novel methods are required to investigate pH within biofilms which provide a multidimensional determination, including temporal, and do not cause a detrimental effect upon the biofilm. Here, I examine two optical methods which utilised different properties of fluorescence to investigate pH microgradients within biofilms designed to mimic cariogenic dental plaque. The two methods are dual-fluorophore, ratiometric, pH-sensitive nanosensors imaged through confocal laser scanning microscopy and SNARF®-4F 5-(and-6)-carboxylic acid imaged through time-correlated single-photon counting and fluorescence-lifetime imaging microscopy. The nanosensors were designed, produced and characterised prior to calibration. The nanosensors were applied to biofilms with limited success, likely due to poor penetration. The optical properties of SNARF®-4F 5-(and-6)-carboxylic acid were characterised, including the two-photon molecular excitation wavelength for use here. The fluorophore was calibrated and applied to bacterial sediment and biofilms and the localised environmental pH assessed following exposure to a fermentable carbohydrate to decrease the pH. Many of the drawbacks experienced with currently employed methods have been addressed by these methods, however further research and development is required.
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Koumanov, Assen. "Theoretical prediction of ionisation properties of proteins /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-535-2.
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Ruddock, Nancy T. "Intracellular pH changes during and following porcine oocyte activation /." free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9974681.
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Correia, Marília Ferreira. "Potencial anticárie dos reservatórios de cálcio, fosfato e fluoreto do biofilme dental." [s.n.], 2018. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289273.
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Orientador: Jaime Aparecido CuryDissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Odontologia de Piracicaba
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Resumo: O biofilme dental apresenta reservatórios orgânicos e inorgânicos de cálcio (Ca), fosfato (Pi) e fluoreto (F) que se liberados para o fluido do biofilme mediante quedas de pH, interfeririam com o grau de saturação do fluido, reduzindo a desmineralização dental. Entretanto, ainda se desconhece a origem responsável pelas mudanças observadas na concentração de Ca, Pi e F no fluido após queda de pH: se derivadas dos reservatórios ou da desmineralização do próprio substrato dental. Em acréscimo, ainda não se determinou a solubilidade desses reservatórios em pHs considerados importantes para interferir com o processo de desmineralização dental. Assim, este trabalho de dissertação teve como objetivos avaliar a influência que a solubilidade dos substratos e dos reservatórios do biofilme exercem na concentração inorgânica do fluido do biofilme, avaliando a cinética dos íons Ca, Pi e F para o fluido após desafio acidogênico. Para isto foram realizados dois estudos in situ, ambos cegos e cruzados. No primeiro foi contemplada a hipótese de que a concentração inorgânica do fluido do biofilme seria influenciada pela desmineralização do substrato, refletindo o grau de solubilidade do mineral que o compõe. Para isto, blocos de esmalte (menos solúvel), dentina (mais solúvel) e acrílico (não solúvel) foram expostos, durante 4 dias, a desafios cariogênicos utilizando glicose a 20%, 8x/ao dia; as variáveis analisadas ao final de cada fase foram composição microbiológica, pH no fluido, Ca, Pi e F no fluido e no estroma (parte sólida) do biofilme antes e 5 min após desafio acidogênico. A influência da quantidade dos reservatórios na concentração inorgânica do fluido foi avaliada no segundo in situ, onde em acréscimo, determinou-se a solubilidade dos mesmos em função de pHs decrescentes. Assim, biofilme dental foi formado, durante 14 dias, sobre blocos de esmalte e acrílico, utilizando diferentes freqüências de exposição a glicose a 20% (0, 2 e 8x/dia), para obtenção de biofilmes com diferentes quantidades de reservatórios. O pH, Ca, Pi e F foram determinados no fluido antes e 5 min após desafio acidogênico, enquanto a solubilidade dos reservatórios foi determinada através da extração de Ca, Pi e F no estroma do biofilme, utilizando tampões com pHs decrescentes (6,5; 5,5; 4,5 e ácido forte). Os resultados desses estudos permitiram observar que houve um aumento significativo de Ca no fluido após queda de pH, ocorrendo de modo semelhante independentemente do substrato onde o biofilme foi formado e da quantidade de reservatórios presentes no seu estroma. Além disso, a solubilidade dos reservatórios demonstrou ser função inversa do pH e direta da concentração de Ca e PI presente. Assim, sugere-se que os reservatórios representam uma importante fonte de mobilização iônica para o fluido do biofilme, porém o fluido não refletiu, na condição analisada, a diferença de solubilidade dos substratos utilizados e dos reservatórios presentes.
Abstract: Dental biofilm presents organic and inorganic reservoirs of calcium (Ca), phosphate (PI) and fluoride (F) that could act as a source of these ions to biofilm fluid during pH drops, reducing dental demineralization. It's still unknown the source responsible for the increase of such ions in biofilm fluid after pH drop, since they could be also derived from mineral dissolution of dental structure. In addiction, there's no clear evidence about the solubility of these reservoirs according to the pHs considered important to interfere with dental demineralization. Thus, this study aimed to evaluate the influence of mineral dissolution of dental structure and also of biofilm reservoirs in the inorganic composition of biofilm fluid, analyzing the kinetics of Ca, PI and F to fluid just after pH drop. Two crossover and blind in situ studies were performed, which the aim of the first one was to evaluate the hypothesis of the inorganic composition of biofilm fluid after pH drop would reflect the mineral solubility of substrate where biofilm was formed. Thus, dental biofilm was formed during 4 days on enamel (less soluble), dentine (more soluble) and acrylic (not soluble) slabs, which were exposed to 8 times/day to 20% glucose solution. In the end of each phase, the acidogenicity, microbiological composition and inorganic concentration of these biofilms were analyzed. The second in situ study evaluated the relation between the amount of Ca, Pi and F reservoirs with the inorganic composition of biofilm fluid and moreover, the potential of these reservoirs to release Ca, Pi and F was estimated according to decreasing pHs (6.5; 5.5; 4.5 and acid). Therefore during 14 days, dental biofilm was formed on enamel and acrylic slabs, which were exposed to different frequencies of 20% glucose (0, 2 and 8 times/day) to form biofilms with different amounts of Ca, Pi and F reservoirs. The biofilm fluid analyses were the same performed in the first study, however the concentration of Ca, Pi and F in biofilm solids were determined after extraction with buffers of 6.5, 5.5 and 4.5 and with acid. A significant increase in Ca concentration was observed after pH fell; nevertheless this increase was the same regardless of the substrate where biofilm was formed and regardless of the amount of Ca, Pi and F reservoirs. Furthermore, biofilm reservoirs showed potential to release Ca, Pi and F at those pHs analyzed, although their solubility were inversely related with the frequency of glucose exposure that biofilm was formed. These findings suggest that biofilm reservoirs are important source of Ca, Pi and F to biofilm fluid after pH drop, however the inorganic concentration of fluid does not reflect the mineral solubility of substrates, the amount and solubility potential of biofilm reservoirs.
Mestrado
Cariologia
Mestre em Odontologia
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Wright, Patricia Anne. "Ammonia stores and excretion in fish : relationship to pH." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/27654.
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The distribution and transfer of ammonia between intracellular and extracellular compartments of fish and the external water environment was investigated. In vivo and in vitro experiments were performed on the freshwater rainbow trout (Salmo gairdneri) and the intact, seawater lemon sole (Parophrys vetulus).
The distribution of ammonia and H⁺ ions were compared between red cells and plasma (in vivo and in vitro) taken from rainbow trout at rest and during hypercapnia. At rest (in vivo and in vitro) measured intracellular ammonia levels were equal to those predicted by the plasma to red cell pH gradient. The same was not true during hypercapnia, where measured red cell ammonia levels were greater than predicted levels. The addition of the Na⁺/K⁺ ATPase inhibitor, ouabain, had no effect on ammonia accumulation during hypercapnia. It was concluded that ammonia is passively distributed according to plasma-to-red cell H⁺ ion distribution in blood at resting pH values, but under hypercapnic conditions, ammonia accumulation must be due to some other active uptake mechanism.
The distribution of ammonia and ¹⁴C-DMO were compared in white muscle, heart, brain, red cells, and plasma of lemon sole (in vivo) at rest, during hypercapnia, and following exercise. The red cell ammonia distribution at rest and during an extracellular acidosis (hypercapnia and exercise) was similar to that found in rainbow trout. Red cells are unusual in that H⁺ ions are passively distributed according to membrane potential (Em), whereas in other tissues, this is not the case. In white muscle, heart, and brain under all experimental conditions, intracellular ammonia levels far exceeded those predicted by transmembrane pH gradients. Calculated ENH₄₊ values in these tissues were very close to published resting values of Em. It was concluded that NH₄₊ is permeable across cell membranes and that intracellular ammonia stores are not determined by transmembrane pH gradients in lemon sole.
The pH of interlamellar water was investigated in rainbow trout by following changes in the downstream pH of expired water using a stopped-flow method. As water flowed over the gills of control fish, there was a significant decrease in water pH. Acetazolamide (carbonic anhydrase (CA) inhibitor) added to the water increased the CO₂ disequilibrium, while CA eliminated the CO₂ disequilibrium relative to control water. Mucus excreted by the fish was found to contain CA activity by the pH-stat technique. It was concluded that water acidification is due to the conversion of excreted CO₂ to HCO₃₋ and H+ at the gill surface.
A possible function of CA at the external gill surface is to facilitate carbon dioxide and ammonia excretion. Acetazolamide or CA added to the water did not alter carbon dioxide (MCO₂) or ammonia (MAmm) excretion in intact rainbow trout. Methazolamide (CA inhibitor) or methazolamide + amiloride (Na⁺ uptake inhibitor) added to the water had no effect on plasma NH₃ tensions (PNH₃), but increased MAmm slightly compared to control fish. In general, methazolamide resulted in an increase in the diffusing capacity of ammonia. The interpretation of these results was complicated by the fact that rapid serial blood sampling resulted in a universal blood alkalosis. The intact resting fish is unsuitable for studying the interaction between water boundary layer chemistry and excretion across the gill.
With the blood-perfused trout head preparation it was demonstrated that MC0₂ and MAmm are linked through chemical reactions in the external water boundary layer adjacent to the gill. Pre-incubation of blood with acetazolamide reduced MC0₂ and MAMM in the blood-perfused head. Increasing the buffering capacity of inspired water, significantly reduced MAMM, but MC0₂ was unaffected. Each of these experimental treatments significantly reduced the acidification of ventilatory water flowing over the gills. It is proposed that the catalysed conversion of excreted C0₂ to form HCO₃₋ and H⁺ ions in the gill boundary layer provides a continual supply of H⁺ ions needed for the removal of NH₃ to NH₄₊, which reduces water NH₃ levels and facilitates ammonia excretion.
Gas transfer variables in the blood-perfused head preparation were compared to intact cannulated fish with and without oral masks. Oxygen uptake (MO₂) and MCO₂ were lower, and MAMM, higher in the blood-perfused head compared to in, vivo values. these discrepancies were due to differences in venous O₂,
CO₂, and ammonia levels, which determine mean gradients across
the gills. It was concluded that the blood-perfused head is a
suitable preparation for studying the interaction between MCO₂ and MAMM because the overall efficiency of transfer of NH₃ CO₂ was very similar between in. vitro and in vivo preparations,Science, Faculty of
Zoology, Department of
Graduate
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Wilson, Christopher Brant. "Measurement of chemical composition and pH profiles near the liquid-vapor interface of aqueous solutions using a unique confocal microscope system /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/9840.
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卓文森 and Man-sum Cheuk. "Effects of sodium pyrophosphate and pH on the kinetics of iron releasefrom the N- and C-terminal binding sites of ovotransferrin." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1988. http://hub.hku.hk/bib/B31208551.
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Neves, Cynthia Der Torossian Torres. "Influência do ph da água de beber na gênese da alteração óssea por cádmio: estudo experimental em ratos." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/23/23139/tde-17062015-111756/.
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O cádmio (Cd) é um metal pesado e dos mais abundantes elementos encontrados no ambiente. Existem evidências de sua relação coma osteopenia, osteoporose, e osteomalacia e fragilidade do tecido ósseo. Este estudo visa avaliar o efeito do pH da água de beber na gênese da alteração óssea provocada pela intoxicação por cádmio. Neste estudo, foram utilizados90 ratosWistar (Ratus Norvegicus albinus), adultos, machos,divididos em 6 grupos, aos quais foram administrados: A -solução de cloreto de Cd(400mg/L) com pH neutro (pH 7,0); B -solução de cloreto de Cd(400mg/L) com pH ácido (pH 5,0); C -solução de cloreto de Cd(400mg/L) com pH básico (pH 8,0). D -pH ácido (pH 5,0); E -pH básico (pH 8,0); F -pH neutro (pH 7,0). Nofêmur esquerdo de cada rato avaliou-se a densidade óssea, por meio do densitômetro de dupla emissão (DEXA), ensaiosbiomecânicos e escala de HU na tomografia computadorizada espiral.Os resultados demostram que a densidade óssea reduziunos grupos que receberam cádmio e no grupo sem administração de cádmio para o pH 5 ocorreu uma redução da densidade mineral óssea (DMO) e do conteúdo mineral ósseo (CMO). A rigidez biomecânica mostrou-se aumentada para o grupocom pH 5 sem cádmio. Como conclusão geral o cádmio reduziu a densidade óssea.The cadmium (Cd) is a heavy metal, one of the most abundant elements found in the environment. There are evidences of its relationship in osteopenia, osteoporosis e osteomalacia and fragility of the bone tissue. This study aims to evaluatethe effect of the pH of the drinking water in the bonealteration origin caused by cadmium intoxication. This study envolved90 wistar rats (Ratus Norvegicus albinus), adults, males,divided in 6groups, were witch one receved: A -cadmium choride solution (400mg/L)withneutral ph (pH 7,0); B -cadmium choride solution(400mg/L) with acid ph (pH 5,0); C -cadmium choride solution(400mg/L)with basic ph(pH 8,0); D -with acid ph (pH 5,0); E -basic ph (pH 8,0); F -neutral pH (pH 7,0).Left femurs from each rat were evaluatedbybone density,DEXA,biomechanictest,HU scale from computerized tomography. The results shows that bone density became lower in the groups that received cadmium. In that wich received no cadmium with pH 5 ocurred an lower level of bone mineral density (BMO) andbone mineral content (BMC).The bone rigidity proved increased in the pH 5 with no cadmium. As a general conclusion, cadmium reduced the bone density.
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Cheuk, Man-sum. "Effects of sodium pyrophosphate and pH on the kinetics of iron release from the N- and C-terminal binding sites of ovotransferrin /." Hong Kong : University of Hong Kong, 1988. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12434838.
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Chintala, Rajesh. "Lime induced changes in the surface and soil solution chemistry of variable charge soils." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5552.
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Thesis (Ph. D.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains ix, 128 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
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Gebhard, Susanne, and n/a. "The Phn and Pst systems of Mycobacterium smegmatis : phosphate transport and gene regulation." University of Otago. Department of Microbiology & Immunology, 2006. http://adt.otago.ac.nz./public/adt-NZDU20070502.112113.
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Phosphate is an essential but often growth-limiting nutrient for bacteria. At low concentrations of phosphate in the growth medium, bacteria induce high-affinity uptake systems for phosphate, and this is usually the ABC-type phosphate specific transport system Pst. In the fully sequenced genomes of pathogenic species of mycobacteria, several copies of the genes encoding for the Pst system (pstSCAB) have been identified and some of these genes have been shown to be virulence factors. The reasons for the presence of multiple copies of pst genes in pathogenic mycobacteria are not understood, and phosphate transport by these bacteria, as well as the gene regulation involved, is poorly characterised. The fast-growing M. smegmatis contains only a single copy of the pst operon, but we recently identified a gene locus containing three genes, phnDCE, which encode for a putative ABC-type phosphate/phosphonate transport system, and a gene, phnF, which encodes for a putative transcriptional regulator of the HutC subfamily of GntR like regulators.
To identify a function for the PhnDCE transport system and to characterise high-affinity phosphate transport in M. smegmatis, we created allelic exchange mutants in phnD and pstS, as well as a phnD pstS double deletion mutant. All three mutants failed to grow in minimal medium containing 10 mM phosphate, while the wildtype was able to grow in the presence of micromolar phosphate concentrations. No differences were observed in complex growth medium. Steady-state levels of [��P]-phosphate uptake were approximately 25% lower in all mutant strains as compared to the wildtype. Kinetics of phosphate uptake in the wildtype strain when grown at low phosphate concentrations (50 [mu]M P[i]) were biphasic, suggesting the presence of two inducible transport systems with apparent K[m] values of 16 [mu]M P[i] and 64 [mu]M P[i], respectively. Analysis of the kinetics of phosphate transport in the mutant strains led us to the proposition that the Pst system has an apparent Km value of ca. 16 [mu]M P[i], and the Phn system has an apparent Km of ca. 60 [mu]M P[i]. A third inducible phosphate transport system, which was active in the double mutant strain, had an apparent K[m] of ca. 90 [mu]M P[i]. Uptake of phosphate in all strains was not inhibited by the presence of excess phosphonates or phosphite, suggesting that all three transport systems were specific for phosphate. The study of phosphate transport in the presence of various metabolic inhibitors revealed that uptake by the Phn and Pst systems is driven by ATP-hydrolysis, consistent with ABC-type transport, while the third, unidentified transport system may be driven by the proton motive force.
We showed that phnDCE formed an operon, and that the promoter area of the operon lies within 200 bp of the start of phnD. To investigate the regulation of the phn and pst genes, β-galacosidase activities of strains carrying transcriptional lacZ-fusions of the pstSCAB, phnDCE and phnF promoter areas, and levels of mRNA of the phn and pst genes were studied. All genes were induced when phosphate concentrations fell below a threshold value of 30 [mu]M, which coincided with a shift in the growth characteristics of M. smegmatis. Expression of the pst operon appeared to be controlled directly by the PhoPR two-component regulatory system, while the phn operon may be under direct or indirect control by PhoPR.
To identify a role for PhnF in the regulation of phn gene expression, we created a phnF deletion mutant. PhnF appeared to repress transcription of phnDCE and phnF under phosphate-replete conditions. We identified two putative binding sequences for PhnF in the intergenic region between phnD and phnF with the sequence TGGTATAGACCA, which is similar to the proposed recognition consensus for HutC-like transcriptional regulators. Using site-directed mutagenesis of these sequences, we demonstrated that they are required for the repression of phnDCE and phnF. To prove PhnF binding to these potential binding sites, we attempted to express the M. smegmatis PhnF protein in E. coli, but could not obtain soluble recombinant protein. Electrophoretic mobility shift assays of the phnDCE promoter fragment using cell-free crude extracts of M. smegmatis were not successful.
We propose that Pst and Phn both constitute high-affinity phosphate specific transport systems of M. smegmatis, and that a third inducible phosphate transport system is present in this bacterium. PhnF is required for repression of phnDCE and phnF transcription under phosphate-replete conditions, while induction of the pst operon, and possibly the phn operon, under phosphate-limited conditions involves the PhoPR system.
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Frasseto, Fernanda. "Relação entre a atividade da isoenzima anidrase carbônica VI, o fluxo salivar e o PH do biofilme dental pré-escolares com cárie na infância." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288106.
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Orientadores: Marinês Nobre dos Santos Uchôa, Regina Célia Rocha PeresDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Este estudo teve como objetivos determinar a atividade da anidrase carbônica VI (ACVI) na saliva de pré-escolares com cárie e investigar a relação entre a experiência cárie (dmfs) e a atividade da ACVI, o fluxo salivar e pH do biofilme antes e após o bochecho com sacarose a 20% em pré-escolares. Trinta pré-escolares com idade entre 45,3 e 80,3 meses foram divididos em 2 grupos: grupo livres de cárie (LC) e grupo com cárie (C). Exames clínicos foram realizados por um examinador de acordo com os critérios da OMS + lesões iniciais de cárie. Em cada individuo, foi determinada a atividade da ACVI, o fluxo salivar e o pH do biofilme dental tanto antes quanto após o bochecho com sacarose. Os resultados foram submetidos aos testes de Wilcoxon, Mann-Whitney e correlação de Spearman (?=0,05). Os resultados mostraram que a atividade da ACVI antes do bochecho e a variação da atividade da ACVI foram maiores na saliva do grupo com cárie que do livres de cárie. Não houve diferença significativa entre os dois grupos após o bochecho. Porém, após o bochecho, a variação do pH do biofilme foi menor em ambos os grupos (p=0,0012 e p=0,0037 para C e LC, respectivamente). E, após o bochecho, houve um aumento significativo do fluxo salivar nos dois grupos (p=0,0003 e p=0,0037 para C e LC, respectivamente). Houve uma correlação negativa da variação entre a atividade da ACVI e a cárie (r=-0,501 e p=0,005). E uma correlação positiva entre a idade das crianças e a experiência de cárie (r=0,456 e p=0,011). Assim, os resultados sugerem que a variação da atividade da ACVI e a idade das crianças está associada com a cárie dentária em pré-escolares
Abstract: This study aimed to determine the activity of the carbonic anhydrase isoenzyme VI (CAVI) in saliva of preschool children with caries and investigate the relationship between caries and the salivary CAVI activity, salivary flow rate (SFR) and biofilm pH before and after a 20% sucrose mouthrinse in preschool children with caries. Thirty preschool children aging from 45.3 to 80.3 months were divided into two groups: caries-free group (CF) and caries group (C). Clinical examinations were conducted by one examiner (kappa=0.95) according to WHO criteria (dmfs) + early caries lesions. From each subject, CAVI activity, SFR and plaque pH were determined before and after a sucrose rinse. The results were submitted to Wilcoxon and Spearman correlation tests (?=0.05). The results showed that the pre-rinse CAVI activity and its variation were higher in saliva from caries children than from CF children. No difference was found between the two groups in the post- rinse salivary CAVI activity. After mouthrinse, the biofilm pH difference were lower in both groups (p=0.0012 and p=0.0037 for the C and CF group respectively). Also, after the sucrose rinse, SFR significantly increased in C and CF groups, (p=0.0003 and p=0.0037). The variation of salivary CA VI activity was negatively correlated with caries (r= -0.501 p=0.005). Child's age showed a positive correlation with caries (r=0.456 and p=0.011). These results suggest that variation of salivary CA VI activity and child's age are associated with dental caries of preschool children
Mestrado
Odontopediatria
Mestre em Odontologia
33
Duerr, Jeffrey Mark. "An analysis of the pH tolerance and substrate preference of isolated skeletal muscle mitochondria from Bufo marinus and Rana catesbeiana." PDXScholar, 1991. https://pdxscholar.library.pdx.edu/open_access_etds/4201.
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The concept of maximal oxygen consumption (VO2 max) implies that there is a limit to the amount of oxygen that can be consumed by an organism in a given time. Many attempts have been made to delineate exactly what factor or factors are limiting to VO2 max. Current models focus on the steps over which oxygen must traverse in order to get from the ambient air to the mitochondria. However, no model has addressed the issue of whether or not carbon dioxide flux may impose a limit to VO2 max. Impedance of carbon dioxide flux may have a deleterious effect on intracellular pH, which in turn, may effect mitochondrial oxidative performance.
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Mendes, Gustavo Adolfo Martins. "Influência do pH de géis clareadores e do tempo de aplicação em esmalte pré dessensibilizado na topografia e cor dental." Universidade Federal de Goiás, 2016. http://repositorio.bc.ufg.br/tede/handle/tede/7798.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Tooth bleaching is one of the procedures with the greatest increase in demand, and the number of products and publications in recent years. However, regardless of the technique to be used bleaching, bleaching agents can cause various changes in tooth structure. Some whitening agents have a pH drop over its response action, which can cause changes in the mineral content of the enamel. These changes may be higher when the time of contact between the bleaching agent and the tooth surface is increased. The aim of this study was to investigate the influence of time of application of whitening gel and its effects on tooth structure in pre-desensitized enamel samples with arginine bicarbonate. Eighty enamel blocks (5.5 x 5.5 mm) were obtained from 40 third molar teeth. These were randomly divided into 16 experimental groups (n = 5). Samples were pre-desensitized with arginine bicarbonate (Colgate Pro-Relief) and then bleached as experimental groups, varying the method of application of whitening gels (Opalescence Boost - Ultradent; Total Blanc - DFL) versus time. The pH range of the gel over the application time, the color variation obtained and roughness of the sample surface were evaluated. Results were subjected to statistical analysis with a significance level of 5%, showed similarity between the gels as the bleaching efficiency and roughness standards and longer application times tend to generate higher roughness values. It was concluded that shorter times of application of the whitening gel are more efficient since they cause less damage to enamel and are able to lighten equally and that the use of desensitizing toothpaste Arginine bicarbonate base prior to bleaching does not affect the whitening effect.
O clareamento dental é um dos procedimentos com o maior aumento de procura, além do número de produtos e publicações nos últimos anos. No entanto, independentemente da técnica clareadora a ser utilizada, os agentes clareadores podem provocar várias alterações na estrutura dental. Alguns agentes de clareamento tem uma queda do pH ao longo da sua reação de ação, o que pode provocar alterações no conteúdo mineral do esmalte. Estas mudanças podem ser mais elevadas quando o tempo de contato entre o agente clareador e a superfície do dente é aumentado. O objetivo desse trabalho foi verificar a influência do tempo de aplicação do gel clareador e seus efeitos sobre a estrutura dental em amostras de esmalte pré-dessensibilizados com Bicarbonato de Arginina. Oitenta blocos de esmalte dental (5,5 x 5,5 mm) foram obtidos a partir de 40 dentes terceiros molares. Estes foram divididos aleatoriamente em 16 grupos experimentais (n=5). As amostras foram pré-dessensibilizadas com Bicarbonato de Arginina (Colgate Pró-Alívio) e em seguida clareadas conforme os grupos experimentais, variando o método de aplicação de géis clareadores (Opalescence Boost – Ultradent; Total Blanc – DFL) em função do tempo. A variação de pH do gel ao longo dos tempos de aplicação, a variação de cor obtida e rugosidade da superfície das amostras foram avaliados. Resultados foram submetidos a análise estatística com nível de significância em 5%, revelaram semelhança entre os géis quanto a eficácia clareadora e padrões de rugosidade e que tempos de aplicação mais longos tendem a gerar maiores valores de rugosidade. Concluiu-se que tempos de aplicação mais curtos do gel clareador são mais eficientes uma vez que geram menos danos ao esmalte e são capazes de clarear de igual forma e que o uso de creme dental dessensibilizante a base de Bicarbonato de Arginina previamente ao clareamento não altera o efeito clareador.
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Beltrami, Mateus. "Desenvolvimento e construção de sensor magnetoelástico de pH com eletrônica portátil." reponame:Repositório Institucional da UCS, 2016. https://repositorio.ucs.br/handle/11338/1259.
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Sensores com material magnetoelástico vêm sendo desenvolvidos pois possibilitam medidas sem contato de fios (wireless). Apresentam variação da frequência de ressonância (redução) quando submetidos a um carregamento de massa. Podem ser empregados para detecção e determinação de grandezas físicas através de instrumentação remota que vem se tornando cada vez mais importante. As grandezas podem ser desde a quantificação de pH até a detecção da presença de microrganismos. Neste trabalho descrevemos um sistema de detecção rápida e wireless de grandezas físicas como pH e a presença de microorganismos. São utilizados como substrato tiras de material magnetoelástico amorfo Metglas 2826MB3. O material foi cortado em tamanhos de 30 mm x 6 mm e 5 mm x 1 mm, através de uma serra de micro corte, sendo parte destas logo em seguida foram revestidas com finas camadas de Cr e Au através de sputtering. Foi desenvolvido um dispositivo portátil com a função de análise de frequência de ressonância das fitas magnetoelásticas. Este dispositivo pode operar completamente de forma autônomo ou em conjunto com computador. Ele é composto de um central de processamento, circuitos auxiliares e interface de entrada e saída de dados. A operação do dispositivo portátil está em expor o material magnetoelástico (transdutor/sensor) a um campo magnético variável com o tempo, que por sua vez responde com uma onda elástica longitudinal que é detectada de forma magnética. Foram realizados ensaios com o transdutor (superfície livre) e também após a aplicação de camadas sensíveis ao pH e bem como a captura de microrganismo. Para os sensores detectores de pH foram utilizadas tiras do transdutor revestidas com Cr e Au sendo nestas aplicada uma camada de cistamina (CYS) para gerar aderência do polímero de pH sintetizado a partir de monómeros de ácido acrílico e acrilato de isooctilo. O sensor de pH foi exposto a uma faixa de pH (1,5 a 7,5) sendo analisado através do dispositivo portátil e comparado com analisador de rede Agilent E5061B. As medidas da frequência de ressonância do sensor de pH apresentaram uma variação de 70 Hz/pH para sensores 30 mm x 5 mm e para sensores de 5 mm x 1 mm foi de 1000 Hz/pH. Também foram realizadas medidas com o transdutor funcionalizado com Poli- L-Lisina para captura de S. cerevisiae. Com a aderência da S. cerevisiae à superfície do sensor, houve uma redução da frequência de ressonância em 531 Hz, que concorda quantitativamente com valores calculados para este carregamento de massa.Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2016-08-09T17:17:16Z No. of bitstreams: 1 Dissertacao Mateus Beltrami.pdf: 5990387 bytes, checksum: 8b30dc1a304d4ed66593186686b04ee2 (MD5)
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Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul, FAPERGS
Sensors with magnetoelastic materials are being developed for possible wireless measurements. They show variation of the resonance frequency (decrease) when subjected to a loading mass. May be employed for detection and determination of physical quantities via remote instrumentation that is becoming increasingly important. These quantities could be the pH of a solution or the detection of the presence of microorganisms. In this work, we describe a rapid and wireless detection system for physical quantities such as pH and the presence of microorganisms. We used as substrates strips of amorphous magnetoelastic material Metglas 2826MB3. The material was cut into strips with sizes of 30 mm x 6 mm and 5 mm x 1 mm, using a micro-dicing saw. Part of these were coated with thin layers of Cr and Au through sputtering. We developed a portable electronic device with the function of determining the resonance frequency of the magnetoelastic strips. This device can operate completely standalone or in conjunction with a computer. It is composed of a central processing, auxiliary circuits and input and output interface of data. The portable device produces a variable magnetic field, which in turn produces a longitudinal elastic wave which is detected magnetically. Tests were carried out with the bare transducer as well as after the application of pH-sensitive layers or material for the capture of microorganisms. For pH sensors we used transducer strips coated with Cr and Au and then applied a layer of cystamine (CYS) to promote adherence to the copolymer of acrylic acid and iso-octyl acrylate. The pH sensor was exposed to a range of pH (1.5 to 7.5) and was measured using the portable device and compared with results from an Agilent E5061B Network Analyzer. The measurements of the resonance frequency of the pH sensor showed a 70 Hz/pH variation for strips of 30 mm x 6 mm and 1000 Hz/pH for strips measuring 5 mm x 1 mm. Measurements were also carried out with the transducer functionalized using poly-l-lysine to capture S. cerevisiae. With the adherence of S. cerevisiae on the sensor surface, there was a reduction of the resonance frequency 531 Hz, which agrees quantitatively with values calculated for mass loading.
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Westman, Ewa. "The impact of protein modification on immunogenicity and arthritogenicity /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-485-6/.
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Soares, Ana Flávia. "Comprometimento do esmalte bovino após escovação em função do condicionamento ácido, clareamento ativado com luz híbrida, concentração e pH dos géis clareadores." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/25/25148/tde-05042013-145654/.
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Este estudo in vitro avaliou a influência do clareamento ativado com luz híbrida, em função da variação do pH e concentração de géis clareadores, e do condicionamento ácido prévio do esmalte bovino na alteração da rugosidade e desgaste após escovação simulada. Fragmentos de esmalte (1,5cm x 0,5cm x 0,4cm) foram divididos em duas partes, ficando uma metade como controle e a outra como área teste. Esta última foi subdividida em duas metades, sendo que uma recebeu o condicionamento ácido somado ao gel clareador e a outra somente o gel clareador. Os espécimes foram divididos aleatoriamente em seis grupos (n=10): C = controle; TBO35LH = Total Blanc Office 35% 1 sessão (5x8) + ativação com luz híbrida LED/Laser; LPS35LH= Lase Peroxide Sense 35% - 1 sessão (5x8) + ativação com luz híbrida LED/Laser; LPS25LH = Lase Peroxide Sense 25% - 1 sessão (5x8) + ativação com luz híbrida LED/Laser; LPL15LH = Lase Peroxide Lite 15% - 1 sessão (5x8) + ativação com luz híbrida LED/Laser; LPL10LHV = Lase Peroxide Lite 10% - 1 sessão (5x8) + ativação com luz híbrida LED/Laser violeta. A rugosidade aritmética (Ra) inicial, após clareamento e após escovação, foi determinada pela média (μm) de três leituras (em cada área sem e com ácido totalizando seis leituras por espécimes) com o rugosímetro Hommel Tester T 1000. Os valores médios do pH foram determinados pelo peagômetro digital Sentron Model 1001 nos tempos inicial e final. Os espécimes foram armazenados em saliva artificial por sete dias, submetidos a 100.000 ciclos de escovação simulada. Após 24 horas o desgaste superficial foi determinado (μm) empregando o mesmo rugosímetro. Em relação ao desgaste e a alteração de rugosidade superficial, os resultados foram submetidos à Anova a dois critérios e a dois critérios de medidas repetidas e posteriormente ao teste de Tukey. Os dados obtidos das leituras de pH foram submetidos à ANOVA a um critério e a dois critérios de medidas repetidas e ao teste de Kruskal Wallis e Tukey para comparações individuais entre os grupos. Para todos os testes o nível de significância foi de 5%. A rugosidade e o desgaste apontaram diferenças estatísticas entre os grupos, principalmente quando comparado à área com e sem ácido. Os géis clareadores apresentaram tendência de diminuição dos valores de pH do tempo inicial para o tempo final, contudo, uma correlação com a rugosidade e com o desgaste não pôde ser estabelecida de forma clara.This in vitro study evaluated the influence of whitening activated with hybrid light on the function variations of the pH level and concentration of bleaching gels and prior acid etching of bovine enamel and the change in roughness and wear after simulated tooth brushing. Fragments of enamel (1.5 cm x 0.5 cm x 0.4 cm) were divided into two parts, one half as the control and the other as the test area. The latter was divided into two halves, one of which received the etching added to the whitening gel and the other with only the whitening gel. The specimens were randomly divided into six groups (n = 10): C = control; TBO35LH = 35% Total Blanc Office 1x session (5x8\') + activation with hybrid light LED/Laser; LPS35LH = 35% Lase Peroxide Sense - 1x session (5x8\') + activation with hybrid light LED/Laser; LPS25LH = 25% Sense Lase Peroxide - 1x session (5x8\') + activation with hybrid light LED/Laser; LPL15LH = 15% Lase Peroxide Lite - 1x session (5x8 \') + activation with hybrid light LED/Laser; LPL10LHV = 10% Lase Peroxide Lite - 1x session (5x8\') + activation with violet hybrid light LED/Laser. The arithmetic roughness (Ra) started after bleaching and after brushing was determined by averaging (μm) the three readings (in each area - with and without acid for a total of six readings per specimen) with a Rugosimeter Hommel Tester T 1000. The mean pH values were determined by the Sentron Model 1001 digital pH meter at the start and end times. The specimens were stored in artificial saliva for seven days, and subjected to 100,000 cycles of simulated brushing. After 24 hours, the surface wear was determined (μm) employing the same roughness meter. In relation to the change in wear and surface roughness, the results were evaluated by two way ANOVA testing for repeated measures and later, a Tukey\'s test. The data obtained from the pH readings were submitted to two way ANOVA testing for repeated measures and the Kruskal Wallis and Tukey tests for the comparisons between the individual groups. The significance level was set at 5% for all the tests. The roughness and wear showed statistical differences between the groups, especially when compared to the area with and without acid. The bleaching gels tended to decrease in pH from the starting time to the final time, however, a correlation with the roughness and wear could not be clearly established.
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Lima, Regina Karla de Pontes [UNESP]. "Avaliação da difusão de íons hidroxila e da atividade antibacteriana de medicação intracanal á base de hidróxido de cálcio." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/101638.
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Este estudo objetivou avaliar a capacidade de liberação e difusão de íons hidroxila, e a atividade antibacteriana de medicações intracanal, in vitro. No primeiro experimento, canais radiculares de dentes bovinos foram instrumentados. Uma cavidade de 4 mm de comprimento, 2 mm de largura e 0,5 mm de profundidade foi confeccionada no terço médio/apical radicular de cada amostra. A abertura coronária e a superfície externa radicular foram seladas com adesivo e esmalte para unhas, exceto a área da cavidade preparada. Os canais radiculares foram preenchidos com as seguintes medicações: G1: hidróxido de cálcio (Ca(OH)2)/soro; G2: Calen; G3: Calen/PMCC; G4: Calen/Clorexidina (CLX) a 0,4%. Os dentes foram armazenados individualmente em frascos contendo água destilada a 37oC. As medições do pH foram realizadas nos períodos de 1, 3, 7, 14, 21, 30 e 60 dias, com utilização de pHmetro digital. Os resultados mostraram aumento significativo do pH a partir de 3 dias para a pasta Calen/CLX e para as demais pastas a partir de 7 até os 14 dias. Para a pasta Calen ocorreu aumento até os 21 dias. A pasta Calen/PMCC apresentou pH mais elevado até 21 dias, sendo os resultados semelhantes para todos grupos aos 30 dias. Aos 60 dias, os maiores valores de pH foram observados para as pastas Calen/PMCC e Calen. Conclui-se que as diferentes composições de pastas à base de Ca(OH)2 proporcionam difusão de íons hidroxila pela dentina radicular. Em outro experimento, 106 dentes humanos unirradiculados tiveram seus canais radiculares contaminados com Enterococcus faecalis e incubados a 37°C por 21 dias. Em seguida, foram divididos de acordo com a medicação intracanal e o período em: G1: Calen - 7 dias; G2: Calen - 14 dias; G3: Calen/PMCC - 7 dias; G4: Calen/PMCC - 14 dias; G5: Calen/CLX a 0,4% - 7 dias; G6: Calen/CLX a 0,4% - 14 dias; G7: Calen/CLX a 1% - 7 dias; G8: Calen/CLX a 1% - 14 dias....
The aim of this study was to evaluate the release and diffusion of hydroxil ions, and the antibacterial activity of intracanal medication, in vitro. At first study, root canals from bovine teeth were instrumented. A cavity with 4 mm of length, 2 mm of width and 0.5 mm of depth was opened at middle/apical third of each sample. The coronal opening and the external surface of the roots were coated with a nail polish layer and a layer of sticky wax, except on the cavity area. Root canals were filled with the following intracanal medication: G1: calcium hydroxide powder with saline solution (Ca(OH)2); G2: Calen; G3: Calen/PMCC; G4: Calen/Chlorhexidine (CHX) 0.4%. Teeth were stored individually in recipients with distilled water at 37oC. Measurements of pH were made at periods of 1, 3, 5, 7, 14, 21, 30 and 60 days, using a digital pH meter. Results showed a significant increase of pH from 3 days for Calen/PMCC, and from 7 until 14 days for the other medications. For Calen, an increase was observed until 21 days. Calen/PMCC showed the highest pH until 21 days, and all the groups had similar results at 30 days. At 60 days, the highest pH values were observed for Calen/PMCC and Calen. It is possible to conclude that different compositions of calcium hydroxide pastes caused diffusion of hydroxil ions through radicular dentin. In another study, 106 single-rooted human teeth had their root canals contaminated with Enterococcus faecalis and incubated at 37oC for 21 days. Then, these teeth were divided according to intracanal medication and periods: G1: Calen - 7 days; G2: Calen - 14 days; G3: Calen/PMCC - 7 days; G4: Calen/PMCC - 14 days; G5: Calen/CHX 0.4% - 7 days; G6: Calen/CHX 0.4% - 14 days; G7: Calen/CHX 1% - 7 days; G8: Calen/CHX 1% - 14 days. Microbiological samples were collected immediately after intracanal medication removal and after seven days. After serial 10-fold dilutions and culture... (Complete abstract click electronic access below)
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Romão, Dayse Andrade 1983. "Validação de um modelo de ciclagens erosivas para estimar o efeito dose-resposta do pH na erosão inicial do esmalte dental." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290564.
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Orientador: Cínthia Pereira Machado TabchouryDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Modelos in vitro devem mimetizar situações próximas das condições reais, entretanto poucos modelos para avaliar erosão em esmalte dentário nestas condições são encontrados na literatura, além de apresentarem algumas limitações. Assim, o objetivo do presente estudo foi validar um modelo de ciclagens erosivas que simule os episódios de erosão/exposição do esmalte dental à saliva, avaliando o efeito dose-resposta para soluções de ácido cítrico com diferentes valores de pH. O modelo de ciclagens erosivas de pH teve uma duração de 5 dias, de forma que blocos de esmalte bovino, selecionados quanto à dureza de superfície e análise de perfilometria, foram imersos em saliva humana estimulada por 1 h a 37ºC sob agitação (100 rpm) antes do primeiro desafio erosivo de cada dia para formação de película adquirida. Em seguida os blocos dentais foram tratados 4 vezes ao dia com a solução de tratamento (2,5 mL/mm2 de área exposta de esmalte dental) sob agitação (100 rpm) por 1 min e nos intervalos entre os tratamentos e durante à noite, os blocos foram imersos em saliva artificial a 37?C sem agitação. Para avaliação do modelo quanto ao efeito dose-resposta ao pH, os blocos (n=12) foram tratados com as seguintes soluções: G1 - cacodilato pH 7,0 (controle); G2 - ácido cítrico pH 2,5; G3 - ácido cítrico pH 3,5; G4 - ácido cítrico pH 4,5; G5 - ácido cítrico pH 5,5; G6 - ácido cítrico pH 7,0. Todas as soluções foram preparadas na concentração de 47,6 mM. Diariamente, ao final da ciclagem e após a imersão na saliva artificial durante à noite, os blocos foram avaliados quanto à dureza de superfície para cálculo da porcentagem de perda de dureza de superfície (%PDS) e ao final do experimento a análise perfilométrica foi novamente realizada. Os resultados foram submetidos à análise de variância e teste de Tukey(p<0,05). Os resultados ao final da ciclagem mostraram que houve um aumento crescente da %PDS em função dos dias na maioria dos grupos e que os blocos tratados com solução de pH 2,5 apresentaram a maior %PDS (p<0,05). Na comparação entre grupos os resultados demonstram que no 4o dia de ciclagem foram verificadas diferenças significativas entre todos os grupos (p<0,05). Já os resultados após saliva apresentaram menores valores de %PDS quando comparados àqueles após ciclagem. Quanto à perfilometria, os blocos dentais tratados com soluções de pH 2,5 e 3,5 apresentaram as maiores perdas de superfície, diferindo entre si e dos demais grupos (p<0,05). Conclui-se que o estudo proposto permitiu a validação de um modelo de ciclagens erosivas que demonstrou efeito dose-resposta para erosão inicial de esmalte dentário após exposição a diferentes valores de pH
Abstract: In vitro models should mimic situations close to the real conditions, however, few models to assess tooth enamel erosion in these conditions are found in the literature, besides presenting some limitations. Thus, the objective of this study was validate a model that simulates cycling episodes of erosion/exposure of dental enamel to saliva, evaluating the dose-response effect for citric acid solutions with different pH values. The model of erosive cycling lasted 5 days, and bovine enamel blocks, selected according to the surface hardness and surface profilometry analysis, were immersed in stimulated human saliva for 1 h at 37°C under agitation (100 rpm) before the first erosive challenge in each day for salivary pellicle formation. Then the dental blocks were treated 4 times daily with the treatment solution (2.5 mL/mm2 per area of exposed enamel) under stirring (100 rpm) for 1 min and in the intervals between treatments and during the nigth the blocks were immersed in artificial saliva at 37?C without stirring. To evaluate the model with regard to the dose-response to pH, blocks (n = 12) were treated with the following solutions: G1 - cacodylate pH 7.0 (control), G2 - citric acid pH 2.5, G3 - acid citric pH 3.5; G4 - citric acid pH 4.5; G5 - citric acid pH 5.5; G6 - citric acid pH 7.0. All the solutions were prepared in a concentration of 47.6 mM. Daily, at the end of the cycling and after immersion in artificial saliva during the night, the blocks were evaluated for surface hardness to calculate the percentage of surface hardness loss (%SHL) and at the end of the experiment profilometry analysis was performed again. The results were submitted to ANOVA and Tukey's test (p<0.05). The results showed a gradual increase in the %SHL at the end of the cycling model as a function of days in most of the groups and the blocks treated with pH 2.5 solution showed the highest %SHL (p<0.05). In the comparison of the groups, the results showed in the 4th cycling day significant differences among all groups (p<0.05). The results after saliva exposure showed lower %SHL when compared to those after cycling. Regarding profilometry, dental blocks treated with solutions pH 2.5 and 3.5 showed the highest surface losses, differing from each other and from the other groups (p<0.05). In conclusion, the proposed study allowed the validation of an erosive cycling model that demonstrated dose-response effect for early tooth enamel erosion after exposure to different pH values
Mestrado
Cariologia
Mestra em Odontologia
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Yanaka, Rodrigo. "Determinação do período de absorção de imunoglobulinas pela mucosa intestinal de cabritos : influência do tempo decorrido entre o nascimento e a ingestão de colostro nos parâmetros bioquímicos, hemogasométricos e imunológicos de caprinos recém-nascidos /." Araçatuba : [s.n.], 2009. http://hdl.handle.net/11449/92208.
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Orientador: Francisco Leydson Formiga FeitosaBanca: Raimundo de Souza Lopes
Banca: José Jurandir Fagliari
Resumo: Os objetivos deste estudo foram determinar o período de absorção intestinal de macromoléculas colostrais em cabritos alimentados com colostro bovino e caprino, e avaliar a variação dos parâmetros bioquímicos, hemogasométricos e imunológicos de cabras e cabritos no período até 75 dias pós-parto. Para tanto, determinaram-se as concentrações séricas de proteína total (refratometria), separação eletroforética das frações protéicas (eletroforese em acetato de celulose), imunoglobulina G (IgG) bovina e caprina (imunodifusão radial), as atividades séricas de aspartatoaminotransferase (AST), fosfatase alcalina (FA), gamaglutamiltransferase (GGT), os teores de creatinina e ureia, e os valores hemogasométricos e glicêmicos, nos momentos zero, dois, sete, 15, 30 e 75 dias pós-parto. Os cabritos que ingeriram colostro bovino até 12 horas pós-nascimento adquiriram títulos regulares de imunoglobulinas. Após 22 horas pós-parto, os cabritos não tiveram absorção adequada de macromoléculas colostrais, sendo classificados como portadores de falha de transferência de imunidade passiva. Aos 75 dias, todos os cabritos possuíam inadequadas concentrações de IgG. Os cabritos alimentados com colostro caprino tiveram concentrações mais elevadas de IgG quando comparados aos daqueles que ingeriram colostro bovino. Aos dois dias pósnascimento a concentração de GGT teve correlação significativa com a IgG, podendo, esta enzima, ser utilizada na avaliação da transferência de imunidade passiva. As cabras e os cabritos tiveram variações protéicas, bioquímicas e hemogasométricas até os 75 dias pós-parto, com pouca relevância clínica.
Abstract: The aims of this study was to determine the absorption period of colostrum macromolecules by intestinal wall of goat kids fed bovine or caprine colostrum, and evaluate the variation of biochemistry, blood gas and immunologic parameters of goats and kids at post-partum period until 75 days. To accomplish these objectives the serum concentrations of total protein (refractometry), electrophoretic proteins fractions separation (acetate cellulose electrophoresis), bovine and caprine immunoglobulin G (IgG) by radial immunodiffusion assay, biochemicals assays for aspartateaminotransferase (AST), alkaline phosphatase (ALP), gammaglutamyltransferase (GGT), creatinine and urea, hole blood assays for blood gas parameters and glycemia were determined at zero, two, seven, 15, 30 and 75 days postpartum. Kids which fed bovine colostrum until 12 hours after birth have acquired regular immunoglobulins titres. After 22 hours postpartum kids didn't presented adequate absorption of colostrum macromolecules, being classified as failure of passive immunity transference. Although all kids presented bovine IgG at 75 days after birth, their low concentrations doesn't provide adequate protection. Kids fed caprine colostrum presented higher concentrations of IgG compared to those fed bovine colostrum. At two days after birth GGT concentration correlated significantly with IgG, so it can be used as passive immunity predictor. Goats and kids had variations on protein, biochemical and blood gas variables until 75 days postpartum, but with physiological and/or nutritional causes, these findings had little clinical relevance for the animals.
Mestre
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Nunes, Ana Rita Silva Martins. "O2/CO2-sensitive cyclic AMP-signalling pathway in peripheral chemoreceptors." Doctoral thesis, Faculdade de Ciências Médicas. UNL, 2013. http://hdl.handle.net/10362/9153.
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RESUMO: O corpo carotídeo (CB) é um pequeno órgão sensível a variações na PaO2, PaCO2 e pH. As células tipo I (células glómicas) do corpo carotídeo, as unidades sensoriais deste órgão, libertam neurotransmissores em resposta às variações dos gases arteriais. Estes neurotransmissores atuam quer em
recetores pré-sinápticos, localizados nas células tipo I, quer em recetores póssinápticos, localizados nas terminações do nervo do seio carotídeo, ou em
ambos. A activação dos recetores pré-sinápticos modula a atividade do corpo
carotídeo, enquanto que, a activação dos recetores pós-sinápticos, de carater
excitatório, desencadeia um aumento da frequência de descarga das fibras do
CSN, com subsequente despolarização dos neurónios do gânglio petroso, e
posterior despolarização de um grupo específico de neurónios do centro
respiratório central, desencadeando, como resposta final, hiperventilação. Estes
recetores pré- e pós-sinápticos podem ser classificados em ionotrópicos ou
metabotrópicos, estando os últimos acoplados a adenilatos ciclases transmembranares (tmAC). O mecanismo exato pelo qual as variações dos gases arteriais são detetadas pelo CB não se encontra ainda completamente elucidado, mas tem sido sugerido que alterações nos níveis de cAMP estejam associadas ao mecanismo de deteção de variações de O2 e CO2. Os níveis de cAMP podem ser regulados através da sua via de síntese, mediada por dois tipos de adenilatos
ciclases: tmAC sensível aos eurotransmissores e adenilato ciclase solúvel (sAC)sensível a variações de HCO3/CO2, e pela sua via de degradação mediada por fosfodiesterases. A via de degradação do cAMP pode ser manipulada
farmacologicamente, funcionando enquanto alvo terapêutico para o tratamento de
patologias do foro respiratório (e.g. asma, hipertensão pulmonar, doença pulmonar obstructiva crónica e apneia do sono), que induzem um aumento da actividade do CB.O trabalho descrito nesta dissertação partiu da hipótese de que a actividade do CB é manipulada por fármacos, que interferem com a via de sinalização do cAMP, tendo sido nosso objectivo geral, investigar o papel do
cAMP na quimiotransdução do CB de rato, e determinar se a actividade dos enzimas responsáveis pela via de sinalização do cAMP é ou não regulada por variações de O2/CO2. Assim, a relevância deste trabalho é a de estudar e identificar possíveis alvos moleculares (sAC, isoformas de tmAC e PDE) com potencial para serem usados no tratamento de patologias relacionadas com o
controlo respiratório.
A primeira parte do presente trabalho, centrou-se na caracterização farmacológica da PDE4 no CB e em tecidos não quimiorecetores (e.g. gânglio cervical superior e artérias carótidas), e na observação do efeito de hipóxia aguda
na acumulação dos níveis de cAMP, induzidos pelos inibidores de PDE, nestes tecidos. A quantificação de cAMP foi efectuada por técnica imunoenzimática (EIA), tendo sido elaboradas curvas de dose-resposta para os efeitos de inibidores, não específicos (IBMX) e específicos para a PDE2 e PDE4 (EHNA, Rolipram e Ro 20-1724), nos níveis de cAMP acumulados, em situações de normóxia (20%O2/5%CO2) e hipóxia (5%O2/5%CO2). A caracterização das PDE no gânglio cervical superior foi aprofundada, utilizando-se a técnica de transferência de energia de ressonância por fluorescência (FRET) em culturas primárias de neurónios, na presença de inibidores não específicos (IBMX) e
específicos para a PDE3 e PDE4 (milrinone e rolipram, respetivamente). Foram igualmente estudadas, através de RT-qPCR, as alterações na expressão de PDE3A-B e PDE4A-D, no gânglio cervical superior, em resposta a diferentes percentagens de oxigénio.
Na segunda parte do trabalho investigou-se a via de síntese do cAMP no CB em resposta a variações na concentração de HCO3/CO2. Em concreto, o protocolo experimental centrou-se na caracterização da sAC, dado que a sua actividade é regulada por variações de HCO3/CO2. A caracterização da expressão e regulação da sAC, em resposta a variações de HCO3/CO2 ,foi efectuada no CB e em tecidos não quimioreceptores periféricos (e.g. gânglio cervical superior, petroso e nodoso) por qRT-PCR. A actividade deste enzima foi caracterizada indirectamente através da quantificação dos níveis de cAMP (quantificação por EIA), induzidos por diferentes concentrações de HCO3/CO2, na presença de MDL-12,33-A, um inibidore da tmAC. A expressão das isoformas da tmAC no CB e gânglio petroso foi determinada por RT-qPCR. Adicionalmente, estudámos a
contribuição relativa da tmAC e sAC no mecanismo de sensibilidade ao CO2 no
CB. Para o efeito foram estudadas as alterações: 1) nos níveis de cAMP
(quantificado por EIA) na presença de diferentes concentrações de HCO3/CO2 e
ao longo do tempo (5-30 min); 2) na ativação da proteína cinase A (PKA, FRET baseado em sensores) em células tipo I do CB; e 3) na frequência de descarga do CSN (registos) na presença e ausência de ativadores e inibidores da sAC,tmAC e PKA. Por último, foi caracterizada a expressão e actividade da sAC nos quimioreceptors centrais (locus ceruleus, rafe e medula ventro-lateral) através de técnicas de RT-qPCR e EIA. A expressão das isoformas da tmAC foi aprofundada no locus coeruleus através de RT-qPCR. Por fim, comparámos a contribuição da tmAC e sAC nos níveis de cAMP no locus coeruleus em condições de normocapnia e hipercapnia.O nosso trabalho teve os seguintes resultados principais: 1) PDE4 está
funcional no corpo carotídeo, artérias carótidas e gânglio cervical superior de rato, embora a PDE2 só se encontre funcional neste último; 2) Os efeitos dos inibidores de PDE nos níveis de acumulação de cAMP foram exacerbados em situações de hipóxia aguda no CB e artérias carótidas, mas foram atenuados no gânglio cervical superior; 3) No gânglio cervical superior, diferentes tipos de células apresentaram uma caracterização específica de PDEs, sugerindo uma subpopulação de células neste gânglio com funções fisiológicas distintas; 4)
Embora todas as isoformas de PDE4 e PDE3 estivessem presentes no gânglio, a PDE3a, PDE4b e a PDE4d foram as isoformas mais expressas. Por outro lado, incubações de gânglio cervical superior, em diferentes percentagens de oxigénio, não alteraram (não regularam) significativamente a expressão das diferentes isoformas de PDE neste órgão; 5) a sAC encontra-se expressa e funcional no CB e nos quimiorecetores centrais estudados (locus coeruleus, rafe e medula
ventrolateral). A sAC apresenta maior expressão no CB comparativamente aos
restantes orgãos estudados, exceptuando os testículos, orgão controlo. Variações
de HCO3/CO2 de 0/0 para 24/5 aumentaram os níveis de cAMP no CB e quimiorecetores centrais, tendo sido o aumento mais significativo observado no CB. Concentrações acima dos 24mM HCO3/5%CO2 não induziram alterações nos níveis de cAMP, sugerindo que a actividade da sAC se encontra saturada em
condições fisiológicas (normocapnia) e que este enzima não desempenha qualquer papel na deteção de situações de hipercapnia; 6) No CB, a expressão das isoformas tmAC1, tmAC4, tmAC6 e tmAC9 é mais elevada comparativamente à expressão da sAC; 7) Utilizamos diferentes inibidores da
tmAC (MDL 12-330A, 500μM, 2’5’-ddADO, 30-300μM, SQ 22536, 200μM) e da
sAC (KH7, 10-100μM) para estudar a contribuição relativa destes enzimas na
acumulação do cAMP no CB. Tanto a tmAC como a sAC contribuem para a acumulação dos níveis de cAMP em condições de hipercapnia. Contudo, existe um maior efeito destes inibidores nas condições de 12 mM HCO3/2.5%CO2 do que em condições de normocapnia e hipercapnia, sugerindo um papel relevante destes enzimas na atividade do CB em situações de hipocapnia; 8) Não se
observaram variações nos níveis de cAMP em resposta a diferentes concentrações de HCO3/CO2 ao longo do tempo (5-30 min). O efeito inibitório induzido por ddADO e KH7 foi sobreponível após 5 ou 30 minutos de incubação em todas as concentrações de HCO3/CO2 estudadas; 9) Por último, verificou-se um aumento na frequência da descarga do nervo do seio carotídeo entre as
condições de normocapnia e hipercapnia acídica. Ao contrário do KH7 (10μM), o
2’5’-ddADO reduziu significativamente a frequência de descarga do nervo, quer
em condições de normocapnia quer de hipercapnia acídica. Contudo, não se
verificou aumento na frequência de descarga do nervo entre normocapnia e hipercapnia isohídrica, sugerindo que a sensibilidade à hipercapnia no CB é mediada por variações de pH. Em conclusão, os resultados decorrentes deste trabalho permitiram demonstrar que, embora os enzimas que medeiam a via de sinalização do cAMP possam ser bons alvos terapêuticos em condições particulares, a sua actividade não é específica para o CB. Os resultados sugerem ainda que o cAMP não é um mediador específico da transdução à hipercapnia neste orgão. Contudo, os
nossos resultados demonstraram que os níveis de cAMP são mais elevados em condições fisiológicas, o que sugere que o cAMP possa ter uma função homeostática neste orgão. Por último, o presente trabalho demonstrou que os
aumentos de cAMP descritos por outros em condições de hipercapnia, não são
observáveis quando o pH se encontra controlado. ------------------ ABSTRACT: The work presented in this dissertation was aimed to establish how specific is
cAMP-signaling pathways in the CB mainly in different CO2 conditions and how O2
concentrations alter/drives the manipulation of cAMP signaling in the CB. The
experimental studies included in this thesis sought to investigate the role of cAMP
in the rat CB chemotransduction mechanisms and to determine whether the enzymes that participate in cAMP signal transduction in the CB are regulated by O2/CO2. We characterized the enzymes involved in the cAMP-signaling pathway in the CB (sAC, tmAC, PDE) under different O2/CO2 conditions. Our results demonstrated that many of these enzymes are involved in CO2/O2 sensing and
while they may be useful in treating conditions with alterations in CO2/O2 sensing,they will not be specific to chemoreception within the CB: 1) PDE4 is ubiquitously expressed in CB and non-chemoreceptor related tissues and their affinity to inhibitors change with O2 tensions in both CB and carotid arteries, and 2) sAC and tmAC are expressed in peripheral and central chemo- and non-chemoreceptor tissues and their effect on cAMP levels do not change between normocapnic and isohydric hypercapnic conditions. Our results provide evidence against a specific role of cAMP as a mediator for O2 and CO2 chemotransduction in the rat CB and emphasized the role of pH in CO2 sensitivity of the CB. Furthermore, our results demonstrate that cAMP levels are maintained higher under physiological
conditions, supporting recent finding from our lab, which all together suggests that
cAMP has a homeostatic function in this organ.
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Yanaka, Rodrigo [UNESP]. "Determinação do período de absorção de imunoglobulinas pela mucosa intestinal de cabritos: influência do tempo decorrido entre o nascimento e a ingestão de colostro nos parâmetros bioquímicos, hemogasométricos e imunológicos de caprinos recém-nascidos." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/92208.
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Os objetivos deste estudo foram determinar o período de absorção intestinal de macromoléculas colostrais em cabritos alimentados com colostro bovino e caprino, e avaliar a variação dos parâmetros bioquímicos, hemogasométricos e imunológicos de cabras e cabritos no período até 75 dias pós-parto. Para tanto, determinaram-se as concentrações séricas de proteína total (refratometria), separação eletroforética das frações protéicas (eletroforese em acetato de celulose), imunoglobulina G (IgG) bovina e caprina (imunodifusão radial), as atividades séricas de aspartatoaminotransferase (AST), fosfatase alcalina (FA), gamaglutamiltransferase (GGT), os teores de creatinina e ureia, e os valores hemogasométricos e glicêmicos, nos momentos zero, dois, sete, 15, 30 e 75 dias pós-parto. Os cabritos que ingeriram colostro bovino até 12 horas pós-nascimento adquiriram títulos regulares de imunoglobulinas. Após 22 horas pós-parto, os cabritos não tiveram absorção adequada de macromoléculas colostrais, sendo classificados como portadores de falha de transferência de imunidade passiva. Aos 75 dias, todos os cabritos possuíam inadequadas concentrações de IgG. Os cabritos alimentados com colostro caprino tiveram concentrações mais elevadas de IgG quando comparados aos daqueles que ingeriram colostro bovino. Aos dois dias pósnascimento a concentração de GGT teve correlação significativa com a IgG, podendo, esta enzima, ser utilizada na avaliação da transferência de imunidade passiva. As cabras e os cabritos tiveram variações protéicas, bioquímicas e hemogasométricas até os 75 dias pós-parto, com pouca relevância clínica.
The aims of this study was to determine the absorption period of colostrum macromolecules by intestinal wall of goat kids fed bovine or caprine colostrum, and evaluate the variation of biochemistry, blood gas and immunologic parameters of goats and kids at post-partum period until 75 days. To accomplish these objectives the serum concentrations of total protein (refractometry), electrophoretic proteins fractions separation (acetate cellulose electrophoresis), bovine and caprine immunoglobulin G (IgG) by radial immunodiffusion assay, biochemicals assays for aspartateaminotransferase (AST), alkaline phosphatase (ALP), gammaglutamyltransferase (GGT), creatinine and urea, hole blood assays for blood gas parameters and glycemia were determined at zero, two, seven, 15, 30 and 75 days postpartum. Kids which fed bovine colostrum until 12 hours after birth have acquired regular immunoglobulins titres. After 22 hours postpartum kids didn’t presented adequate absorption of colostrum macromolecules, being classified as failure of passive immunity transference. Although all kids presented bovine IgG at 75 days after birth, their low concentrations doesn’t provide adequate protection. Kids fed caprine colostrum presented higher concentrations of IgG compared to those fed bovine colostrum. At two days after birth GGT concentration correlated significantly with IgG, so it can be used as passive immunity predictor. Goats and kids had variations on protein, biochemical and blood gas variables until 75 days postpartum, but with physiological and/or nutritional causes, these findings had little clinical relevance for the animals.
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Lima, Regina Karla de Pontes. "Avaliação da difusão de íons hidroxila e da atividade antibacteriana de medicação intracanal á base de hidróxido de cálcio /." Araraquara : [s.n], 2010. http://hdl.handle.net/11449/101638.
Full textAbstract:
Orientador: Juliane Maria Guereiro TanomaruBanca: Evandro Watanabe
Banca: Igor Prokopowitsch
Banca: Gisele Faria
Banca: Idomeo Bonetti Filho
Resumo: Este estudo objetivou avaliar a capacidade de liberação e difusão de íons hidroxila, e a atividade antibacteriana de medicações intracanal, in vitro. No primeiro experimento, canais radiculares de dentes bovinos foram instrumentados. Uma cavidade de 4 mm de comprimento, 2 mm de largura e 0,5 mm de profundidade foi confeccionada no terço médio/apical radicular de cada amostra. A abertura coronária e a superfície externa radicular foram seladas com adesivo e esmalte para unhas, exceto a área da cavidade preparada. Os canais radiculares foram preenchidos com as seguintes medicações: G1: hidróxido de cálcio (Ca(OH)2)/soro; G2: Calen; G3: Calen/PMCC; G4: Calen/Clorexidina (CLX) a 0,4%. Os dentes foram armazenados individualmente em frascos contendo água destilada a 37oC. As medições do pH foram realizadas nos períodos de 1, 3, 7, 14, 21, 30 e 60 dias, com utilização de pHmetro digital. Os resultados mostraram aumento significativo do pH a partir de 3 dias para a pasta Calen/CLX e para as demais pastas a partir de 7 até os 14 dias. Para a pasta Calen ocorreu aumento até os 21 dias. A pasta Calen/PMCC apresentou pH mais elevado até 21 dias, sendo os resultados semelhantes para todos grupos aos 30 dias. Aos 60 dias, os maiores valores de pH foram observados para as pastas Calen/PMCC e Calen. Conclui-se que as diferentes composições de pastas à base de Ca(OH)2 proporcionam difusão de íons hidroxila pela dentina radicular. Em outro experimento, 106 dentes humanos unirradiculados tiveram seus canais radiculares contaminados com Enterococcus faecalis e incubados a 37°C por 21 dias. Em seguida, foram divididos de acordo com a medicação intracanal e o período em: G1: Calen - 7 dias; G2: Calen - 14 dias; G3: Calen/PMCC - 7 dias; G4: Calen/PMCC - 14 dias; G5: Calen/CLX a 0,4% - 7 dias; G6: Calen/CLX a 0,4% - 14 dias; G7: Calen/CLX a 1% - 7 dias; G8: Calen/CLX a 1% - 14 dias.... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The aim of this study was to evaluate the release and diffusion of hydroxil ions, and the antibacterial activity of intracanal medication, in vitro. At first study, root canals from bovine teeth were instrumented. A cavity with 4 mm of length, 2 mm of width and 0.5 mm of depth was opened at middle/apical third of each sample. The coronal opening and the external surface of the roots were coated with a nail polish layer and a layer of sticky wax, except on the cavity area. Root canals were filled with the following intracanal medication: G1: calcium hydroxide powder with saline solution (Ca(OH)2); G2: Calen; G3: Calen/PMCC; G4: Calen/Chlorhexidine (CHX) 0.4%. Teeth were stored individually in recipients with distilled water at 37oC. Measurements of pH were made at periods of 1, 3, 5, 7, 14, 21, 30 and 60 days, using a digital pH meter. Results showed a significant increase of pH from 3 days for Calen/PMCC, and from 7 until 14 days for the other medications. For Calen, an increase was observed until 21 days. Calen/PMCC showed the highest pH until 21 days, and all the groups had similar results at 30 days. At 60 days, the highest pH values were observed for Calen/PMCC and Calen. It is possible to conclude that different compositions of calcium hydroxide pastes caused diffusion of hydroxil ions through radicular dentin. In another study, 106 single-rooted human teeth had their root canals contaminated with Enterococcus faecalis and incubated at 37oC for 21 days. Then, these teeth were divided according to intracanal medication and periods: G1: Calen - 7 days; G2: Calen - 14 days; G3: Calen/PMCC - 7 days; G4: Calen/PMCC - 14 days; G5: Calen/CHX 0.4% - 7 days; G6: Calen/CHX 0.4% - 14 days; G7: Calen/CHX 1% - 7 days; G8: Calen/CHX 1% - 14 days. Microbiological samples were collected immediately after intracanal medication removal and after seven days. After serial 10-fold dilutions and culture... (Complete abstract click electronic access below)
Doutor
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Serra, Peinado Carla. "Papel del citoesqueleto de actina en la regulación de la H+-ATPasa vacuolar de complejo de Golgi." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/663846.
Full textAbstract:
La vía secretora se caracteriza por la acidificación progresiva de sus orgánulos, este gradiente es crucial para funciones tales como la modificación postraduccional de proteínas o el trafico de membranas. El principal responsable de generar y mantener este gradiente es la H+-ATPasa vacuolar (V-ATPase), que transporta protones desde el citosol hacía el interior del Golgi. Esta bomba está compuesta de dos dominios, el dominio V1 y el V0, a su vez ambos están formados por varias subunidades. Se ha descrito que las subunidades B y C del dominio V1 contienen dominios de unión a actina.
Existen significantes similitudes entre los efectos subcelulares producidos por la despolimerización de actina y la inhibición farmacológica de la V-ATPasa: Alteración de transporte vesicular Golgi-Retículo endolplasmatico y Golgi-membrana plasmática, alcalinización del complejo de Golgi, dilatación de las cisternas de Golgi. Teniendo en cuenta que dos subunidades de la V-ATPasa tienen la capacidad de unirse a los microfilamentos de actina, nosotros hipotetizamos que estos podrían participar en la homeostasis del pH de Golgi a través de la regulación de la V-ATPasa, particularmente la actina podría estar manteniendo la asociación de los dominios V1 y V0.
Generamos un constructo de la subunidad B conjugado con GFP (B2-GFP) que se incorporaba en el dominio V1. Observamos que este constructo se localizaba en los compartimentos distales del complejo de Golgi y que translocaba al citosol al despolimerizar la actina. Diferentes ensayos bioquímicos nos sirvieron para confirmar que la despolimerización de actina inducía la disociación de los dominios V1 y V0 de la V-ATPasa. Además, detectamos interacción entre la actina y las subunidades B y C. Finalmente, está descrito que la V-ATPasa se localiza en los dominios ricos en colesterol de la membrana plasmática y que el citoesqueleto de actina juega un papel importante en la organización de estos dominios, lo que observamos fue que la desorganización de los dominios ricos en colesterol inducía una subida del pH de Golgi.
Con todo, concluimos que la actina regula el pH de Golgi a través del mantenimiento de la asociación de los dos dominios de la ATPasa gracias a su unión a las subunidades B y C además de su papel en el mantenimiento de los dominios ricos en colesterol.We previously reported that agents that depolymerize actin filaments promote the alkalization of the Golgi stack and the trans-Golgi network. Vacuolar-type H-translocating ATPase (V-ATPase) is responsible of proton translocation and acidification of Golgi lumen. V-ATPase is a multisubunit complex composed of two domains (V1 and V0). Moreover, two subunits of V1 domain contain actin binding sides, subunit B and C. In this work we hypothesize that actin filaments could have a role in the maintaining of V1 and V0 domain association. We have generated a GFPtagged subunit B2 construct that is incorporated into the V1 domain, this construct localizes at distal Golgi compartments and translocate to cytosol upon actin depolymerization. Several biochemical assays confirmed that microfilaments distruption induces dissociation of V1-V0 domains. Moreover, we detected interaction between subunits B-C and actin filaments. Finally, V-ATPase is localized in lipid raft domains of plasma membrane and actin filaments participate in organization of these domains. We observed that lipid raft disorganization promotes an increase of intra-Golgi pH. Overall, we conclude that actin regulates the Golgi pH homeostasis maintaining the coupling of V1-V0 domains of V-ATPase through the binding of microfilaments to subunits B and C and preserving the integrity of lipid raft.
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Salgado, Lívia. "Influência da alteração do pH e da degradação enzimática na rugosidade das superfícies de resinas compostas." Universidade Federal de Juiz de Fora, 2015. https://repositorio.ufjf.br/jspui/handle/ufjf/414.
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FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais
Avaliou-se a rugosidade das superfícies de duas resinas compostas, antes e após a sua imersão em solução aquosa com diferentes pH e solução enzimática. Para a confecção dos 60 corpos de prova, 30 para cada resina composta, utilizou-se uma matriz de acrílico com 5mm de diâmetro e 2mm de espessura, sobre uma tira de poliéster posicionada em uma placa de vidro estéril que foram preenchidas com as resinas compostas Filtek Z350 (3M ESPE) e Empress Direct (Ivoclar-Vivadent), em um único incremento e sobre esta foi colocada outra tira de poliéster e procedeu a fotopolimerização por 40s. Os corpos de prova foram divididos 06 grupos (n=10) de acordo com a solução empregada: água deionizada (Grupos ZA e EA); hidróxido de sódio com pH 13.2 (Grupos ZNa e ENa) e solução enzimática de colesterol esterase (Grupos ZE e EE). Para dar acabamento utilizou-se uma sequência decrescente de granulação de lixas d’água: 600, 1000, 1200, 1500 e 2000 e para o polimento, suspensões de alumina (Arotec, São Paulo, SP, Brasi): 1μm, 0,3μm e 0,05μm. Após o polimento foram armazenados em estufa a 37°C durante 7 dias e realizadas 3 medições de cada superfície no rugosímetro e realizada a média e foram imersos individualmente nas soluções por 30 dias e mantidos em estufa a 37°C, a cada 7 dias as soluções eram trocadas. Após 30 dias foram realizadas mais 3 medições da rugosidade das superfícies e realizada a média. Foi realizada ANOVA e o teste de Tukey. A partir dos resultados obtidos conclui-se que as resinas compostas testadas apresentaram degradação hidrolítica apenas na solução aquosa por um período de imersão de 30 dias.
The roughness of the surfaces was evaluated two composites before and after their immersion in aqueous solutions with different pH and the enzyme solution. For producing the 60 test specimens, 30 for each composite was used an acrylic matrix with 5mm in diameter and 2mm thick on a polyester strip placed on a sterile glass plate were filled with the resins Filtek Z350 (3M ESPE) and Empress Direct (Ivoclar Vivadent-) in a single increment and this was placed on another strip of polyester and proceeded to light curing for 40 seconds. The specimens were divided 06 groups (n = 10) according to the used solution: deionized water (ZA Groups and EA); sodium hydroxide at pH 13.2 (ZNA Groups ENA) and enzyme solution of cholesterol esterase (ZE and EE groups). To finish used a descending sequence of sanding granulation water: 600, 1000, 1200, 1500 and 2000 and for polishing alumina suspensions (Arotec, São Paulo, SP, Brasi): 1μm, and 0,3μm 0,05μm. After polishing were stored at 37 ° C for 7 days and 3 measurements carried out on each surface roughness and the carried medium and were immersed in individual solutions and kept for 30 days at 37 ° C every 7 days the solutions were exchanged. After 30 days there were over 3 measurements of surface roughness and made average. ANOVA and Tukey test was performed. From the results obtained it is concluded that the composites tested showed hydrolytic degradation in aqueous solution only for a period of 30 days immersion.
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Reinholz, Uwe. "Darstellung eines Referenzmaterials für die ortsaufgelöste Wasserstoffanalytik in oberflächennahen Schichten mittels Kernreaktionsanalyse." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1176198574703-16051.
Full textAbstract:
Obwohl Wasserstoff omnipräsent ist, ist seine Analytik anspruchsvoll und es stehen nur wenige analytische Verfahren zur Auswahl. Unter diesen nimmt die auf einer Kernreaktion von Wasserstoff und Stickstoff basierende N-15-Methode einen herausragenden Platz ein. Sie liefert eine ortsaufgelöste Wasserstoffkonzentration bis in den ppm-Bereich in oberflächennahen Schichten (kleiner 2 µm). Gegenstand der Arbeit sind die Darstellung der Theorie der N-15-Kernreaktionsanalyse (NRA), des experimentellen Aufbaus des entsprechenden Strahlrohrs am Ionenbeschleuniger der BAM und der Auswertung der Messergebnisse. Ziel ist die erstmalige Charakterisierung eines Referenzmaterials für die H-Analytik auf Basis von amorphen Silizium (aSi) auf einem Si[100]-Substrat. International wird von den metrologischen Instituten NIST [REE90] und IRMM [VAN87] je ein Referenzmaterial für die Heißextraktion in Form von Titanplättchen angeboten. Diese sind aber für die oberflächennahen Verfahren (NRA, ERDA, GDOES, SIMS) nicht nutzbar, da die oberflächennahe Konzentration von Wasserstoff in Titan nicht konstant ist. Die Homogenität der mittels CVD abgeschiedenen aSi:H-Schichten wurde untersucht. Dazu wurden pro Substrat für ca. 30 Proben die Wasserstofftiefenprofile gemessen, mittels eines innerhalb der Arbeit entstandenen Programms entfaltet und der statischen Auswertung unterzogen. Das Ergebnis waren Mittelwert und Standardabweichung der Wasserstoffkonzentration, sowie ein Schätzer für den Beitrag der Inhomogenität zur Meßunsicherheit. Die Stabilität des potentiellen Referenzmaterials wurde durch die Konstanz der Ergebnisse von Wiederholtungsmessungen der Wasserstoffkonzentrtion während der Applikation einer hohen Dosis von N-15 Ionen bewiesen. In einem internationalen Ringversuch wurde die Rückführbarkeit der Messergebnisse nachgewiesen. Teilnehmer waren 13 Labore aus 7 Ländern. Eingesetzt wurden N-15 und F-19 NRA, ERDA und SIMS. Besonderer Beachtung wurde der Bestimmung der Messunsicherheiten gewidmet. Für die Charakterisierung der aSi:H-Schichten wurden neben der NRA die Weißlichtinterferometrie, Ellipsometrie, Profilometrie und Röngenreflektometrie, sowie die IR- und Ramanspektroskopie genutzt. Die Stöchiometrie des eingesetzten Standardmaterials Kapton wurde mittels NMR-Spekroskopie und CHN-Analyse überprüft. [VAN87] Vandendriessche, S., Marchandise, H., Vandecasteele, C., The certification of hydrogen in titanium CRM No318, Brüssel-Luxembourg,1987 [REE90] Reed, W.P., Certificate of Analysis SRM 352c, Gaithersburg, NIST, 1990
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Niigaki, Juliana Ikeda. "Dopplervelocimetria da artéria cerebral média fetal na predição da acidemia no nascimento em gestações com insuficiência placentária." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/5/5139/tde-08042014-090931/.
Full textAbstract:
Objetivo: Avaliar a relação das alterações de fluxo na artéria cerebral média (ACM) com a ocorrência de acidemia no nascimento, em gestações com insuficiência placentária. Métodos: estudo transversal prospectivo com 91 gestações com diagnóstico de insuficiência placentária pelo Doppler de artéria umbilical (AU) alterado (índice de pulsatilidade [IP] > p95). Os critérios de inclusão foram: gestações únicas com idade gestacional (IG) superior a 26 semanas completas, membranas ovulares íntegras, ausência de anomalias cromossômicas ou congênitas. Os parâmetros da dopplervelocimetria analisados foram: IP da AU, IP da ACM, pico de velocidade sistólica (PVS) da ACM, relação cerebroplacentária (RCP) e índice de pulsatilidade para veias (IPV) do ducto venoso (DV). Foi analisada a última avaliação fetal realizada imediatamente antes do parto ou anterior à corticoterapia. Todos os parâmetros foram analisados por meio do escore zeta ou múltiplos da mediana (MoM), baseados nas médias, desvio-padrão e valores de referência para cada IG. Imediatamente após o parto, uma amostra de sangue da artéria umbilical foi obtida para a medida do pH, e os casos classificados de acordo com a presença (pH < 7,20) ou ausência de acidemia no nascimento. Resultados: Quarenta e sete (51,6%) recémnascidos apresentaram acidemia no nascimento. Os fetos que evoluíram com acidemia apresentaram valor de escore zeta do IP da AU significativamente maior (mediana 2,1 vs 1,7; p=0,014), assim como maior proporção de casos com diástole zero ou reversa (51,0% vs 31,8%; p=0,006). Quanto à ACM, o escore zeta mostrou-se significativamente menor nos casos com pH < 7,20 (mediana -2,7 vs -2,1; p=0,042), porém, em relação ao PVS não foi possível estabelecer diferença significativa entre os grupos (p=0,051). A acidemia no nascimento se associou a menores valores de RCP (mediana 0,5 vs 0,7; p=0,006), porém não ao seu escore zeta (p=0,055). Em relação ao território venoso, maiores valores do escore zeta do IPV do DV associaram-se à acidemia (mediana 2,4 vs 0,6; p=0,015). Na análise de correlação entre os valores de pH no nascimento e os resultados da avaliação da dopplervelocimetria fetal, foi constatada correlação significativa entre o valor do pH no nascimento e o escore zeta do IP da AU (rho=-0,31; p=0,003), IP da ACM (rho=0,26; p=0,012), da RCP (rho 0,25; p=0,015) e IPV do DV (rho=-0,32; p=0,002), e PVS da ACM MoM (rho=-0,21; p=0,042). A regressão logística identificou o escore zeta do IP da AU e escore zeta IP da ACM como variáveis independentes para a predição de acidemia no nascimento, classificando corretamente 67,03% dos casos. Conclusão: em casos de insuficiência placentária, o IP da AU e da ACM são preditores independentes associados com a acidemia no nascimento. Este estudo reforça que o grau de insuficiência placentária e a capacidade de adaptação fetal estão diretamente relacionados com a acidemia no nascimentoObjectives: To evaluate the relationship between middle cerebral artery (MCA) parameters and acidemia at birth, in pregnancies complicated by placental insufficiency. Methods: The study was performed as a prospective cross-sectional analysis of Doppler measurements in 91 patients with the diagnosis of placental dysfunction by abnormal umbilical artery (UA) Doppler (pulsatility index [PI] > p95). Inclusion criteria were: singleton pregnancy, intact membranes, abscence of fetal congenital or chromosomal abnormalities. The Doppler parameters analyzed were: UA PI, MCA PI, MCA peak systolic velocity (PSV), cerebroplacental ratio (CPR) and pulsatilility index for veins (PIV) of ductus venosus (DV). It was analyzed the last assessment obtained right before birth or the antenatal steroids. Umbical artey blood samples were collected at birth, and acidemia was defined as pH below 7.20. Results: Forty seven (51.6%) newborns had acidemia at birth. Those who developed acidemia showed a UA PI z-score significantly higher (median 2.1 vs 1.7, p = 0.014), as well as a higher proportion of cases with absent or reverse end diastolic flow (51.0% vs 31.8%, p = 0.006). Regarding the MAC, the PI z-score was significantly lower in cases with pH < 7.20 (median -2.7 vs. -2.1, p = 0.042), but concerning PSV z-score, no significant relation between the groups could be established (p = 0.051).The acidemia at birth was associated with lower values of CPR (median 0.5 vs 0.7, p = 0.006), but not with its z-score (p = 0.055). In relation to the venous territory, greater values of DV PIV z-score were associated with acidemia (median 2.4 vs 0.6, p = 0.015).The correlation analysis between the pH values at birth and the Doppler measurements, a significant correlation was observed between the pH at birth and UA PI z-score (rho = -0.31, p = 0.003 ), MCA PI z-score (rho = 0.26, p = 0.012), CPR z-score (rho 0.25, p = 0.015), PIV DV zscore (rho = -0.32, p = 0.002), and PSV MCA MoM (rho = -0.21, p = 0.042). Logistic regression identified the UA PI z-score and the MCA PI z-score as independent predictors for acidemia at birth, correctly classifying 67.03% of cases. Conclusion: In pregnancies with placental insufficiency, the UA PI and the MCA PI are independent predictors associated with acidemia at birth. This study reinforces that the degree of placental insufficiency and the fetal adaptation capacity are directly related to acidemia at birth
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Cheng, Chin-Min. "Leaching of coal combustion products field and laboratory studies /." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1133195856.
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Reinholz, Uwe. "Darstellung eines Referenzmaterials für die ortsaufgelöste Wasserstoffanalytik in oberflächennahen Schichten mittels Kernreaktionsanalyse." Doctoral thesis, Technische Universität Dresden, 2005. https://tud.qucosa.de/id/qucosa%3A24977.
Full textAbstract:
Obwohl Wasserstoff omnipräsent ist, ist seine Analytik anspruchsvoll und es stehen nur wenige analytische Verfahren zur Auswahl. Unter diesen nimmt die auf einer Kernreaktion von Wasserstoff und Stickstoff basierende N-15-Methode einen herausragenden Platz ein. Sie liefert eine ortsaufgelöste Wasserstoffkonzentration bis in den ppm-Bereich in oberflächennahen Schichten (kleiner 2 µm). Gegenstand der Arbeit sind die Darstellung der Theorie der N-15-Kernreaktionsanalyse (NRA), des experimentellen Aufbaus des entsprechenden Strahlrohrs am Ionenbeschleuniger der BAM und der Auswertung der Messergebnisse. Ziel ist die erstmalige Charakterisierung eines Referenzmaterials für die H-Analytik auf Basis von amorphen Silizium (aSi) auf einem Si[100]-Substrat. International wird von den metrologischen Instituten NIST [REE90] und IRMM [VAN87] je ein Referenzmaterial für die Heißextraktion in Form von Titanplättchen angeboten. Diese sind aber für die oberflächennahen Verfahren (NRA, ERDA, GDOES, SIMS) nicht nutzbar, da die oberflächennahe Konzentration von Wasserstoff in Titan nicht konstant ist. Die Homogenität der mittels CVD abgeschiedenen aSi:H-Schichten wurde untersucht. Dazu wurden pro Substrat für ca. 30 Proben die Wasserstofftiefenprofile gemessen, mittels eines innerhalb der Arbeit entstandenen Programms entfaltet und der statischen Auswertung unterzogen. Das Ergebnis waren Mittelwert und Standardabweichung der Wasserstoffkonzentration, sowie ein Schätzer für den Beitrag der Inhomogenität zur Meßunsicherheit. Die Stabilität des potentiellen Referenzmaterials wurde durch die Konstanz der Ergebnisse von Wiederholtungsmessungen der Wasserstoffkonzentrtion während der Applikation einer hohen Dosis von N-15 Ionen bewiesen. In einem internationalen Ringversuch wurde die Rückführbarkeit der Messergebnisse nachgewiesen. Teilnehmer waren 13 Labore aus 7 Ländern. Eingesetzt wurden N-15 und F-19 NRA, ERDA und SIMS. Besonderer Beachtung wurde der Bestimmung der Messunsicherheiten gewidmet. Für die Charakterisierung der aSi:H-Schichten wurden neben der NRA die Weißlichtinterferometrie, Ellipsometrie, Profilometrie und Röngenreflektometrie, sowie die IR- und Ramanspektroskopie genutzt. Die Stöchiometrie des eingesetzten Standardmaterials Kapton wurde mittels NMR-Spekroskopie und CHN-Analyse überprüft. [VAN87] Vandendriessche, S., Marchandise, H., Vandecasteele, C., The certification of hydrogen in titanium CRM No318, Brüssel-Luxembourg,1987 [REE90] Reed, W.P., Certificate of Analysis SRM 352c, Gaithersburg, NIST, 1990
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Francisconi, dos Rios Luciana Fávaro, Leslie Casas-Apayco, Marcela Pagani Calabria, Paulo Afonso Silveria Francisconi, Ana Flávia Sanches Borges, and Linda Wang. "Role of chlorhexidine in bond strength to artificially eroded dentin over time." Quintessence Publishing Group, 2015. http://hdl.handle.net/10757/607257.
Full textAbstract:
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.PURPOSE: To assess the long-term effect of a 2% aqueous chlorhexidine (CHX) solution on bond strength to artificially eroded dentin compared to sound dentin. MATERIALS AND METHODS: Flat mid-coronal dentin surfaces of extracted third molars (n = 28) were subjected only to grinding with a 600-grit SiC paper for 1 min (sound dentin S, n = 14) or additionally to erosive pH cycling with a cola-based soft-drink (eroded dentin E, n = 14). After acid etching, rinsing, and air drying, S and E were rehydrated with 1.5 μl of 2% CHX (S2%, n = 7; E2%, n = 7) or of distilled water (control SC, n = 7; EC, n = 7). Composite buildups were incrementally constructed with Filtek Z350 following Adper Single Bond 2 application. Specimens were sectioned into beams, which were subjected to microtensile testing immediately or after 6 or 12 months of aging. Fractured surfaces were observed under a digital microscope (50X magnification). Microtensile bond strength (μTBS) (MPa) was analyzed by three-way ANOVA and Tukey's tests (α = 0.05) and failure mode by the Kruskal-Wallis test (α = 0.05). RESULTS: Compared to sound dentin, eroded dentin was consistently related to lower μTBS. Immediately and after 12-month aging, the effect of CHX was insignificant, but it was significant after 6-month aging, when it conserved the bond strength to both eroded and sound dentin. The percentage of adhesive and mixed failures were equivalent, and significantly more frequent than cohesive failures, whether in dentin or in composite. CONCLUSION: The 2% CHX effect on bond strength conservation to both eroded and sound dentin was not found to be persistent.
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