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Cortes, Morales Myrna Carolina. "Characterization of cross-country ski base material." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-85856.
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Cross-country skiing has developed to become one of the most competitive winter sports, where a skier can win by fractions of seconds. Joint efforts between ski technicians and scientist have allowed the development of methodologies to prepare the ski surface, yet much of the knowledge up to date is based on the experience of the technicians. In this sense, much attention is focused on the ski base, given that the friction at the base is an important factor that will define how fast a ski can glide. Ski base preparation is an extensive procedure, due to the several parameters that have to be taken into account. Much disagreement has risen regarding the best way to optimize the base. Thus, a complete characterization of the ski base can help to provide some clarity on the factors that affect friction. This work presents the results of the characterization of the ski base through the preparation process by observing and measuring different aspects, using characterization techniques such as LOM, optical profilometry, contact angle, DSC and XCT. The results suggest that the mechanical machining of the surface can influence wax retention and hydrophobicity. Furthermore, it is seen that wax is present after the first waxing step, despite the constant brushing and scraping. No major changes were observed for the crystallinity. Finally, the amount of graphite on the surface was quantified. This is hoped to be helpful for ski technicians and athletes alike to improve the performance of their skis.
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Halbach, Felix. "Structural and functional characterization of the yeast Ski2-Ski3-Ski8 complex." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-160779.
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The Ski2-Ski3-Ski8 (SKI) complex is a conserved multi-protein assembly required for the cytoplasmic functions of the exosome, including messenger RNA (mRNA) turnover, surveillance
and interference. The helicase Ski2, the tetratricopeptide repeat (TPR) protein Ski3 and the �-propeller Ski8 assemble in a heterotetramer with 1:1:2 stoichiometry. While the function of the Ski2-Ski3-Ski8 complex as a general cofactor of the cytoplasmic exosome has been well established, it remains largely unclear how it contributes to the regulation of the
exosome. The PhD thesis at hand addresses this question by investigating the structural and biochemical properties of the Ski2-Ski3-Ski8 complex.
Solving the crystal structure of the 113 kDa helicase region of S. cerevisiae Ski2 by experimental phasing revealed the presence of a canonical DExH core and an atypical accessory domain that is inserted in the helicase core. This insertion domain binds ribonucleic acid (RNA) unspeci�cally and is located at the RNA entry site of the helicase core. The overall architecture of Ski2 including the presence of an accessory domain is similar to
the structure of the related helicase Mtr4, but the structural and biochemical properties of the accessory domains from both proteins are di�erent. The Ski2 insertion domain is not required for formation of the Ski2-Ski3-Ski8 complex. Its removal allowed to crystallize a Ski2�insert-Ski3-Ski8 complex from S. cerevisiae, and the crystal structure of this 370 kDa core complex was determined experimentally. It shows that Ski3 forms an array of 33 TPR motifs, creating a sca�old for the other subunits. Ski3 and the two Ski8 subunits bind the helicase core of Ski2 and position it centrally within the complex. This creates an extended internal RNA channel and modulates the enzymatic
properties of the Ski2 helicase. Both Ski8 subunits are bound through a structurally conserved motif. A similar motif is present and functional in yeast Spo11, a protein that initiates deoxyribonucleic acid (DNA) double strand breaks during meiotic recombination. Association of Ski8 to either complex is mutually exclusive, rationalizing how Ski8 can perform its two distinct roles in mRNA metabolism and meiotic recombination.
Biochemical studies suggest that the SKI complex can thread RNAs directly to the exosome, coupling the helicase and the exoribonuclease through a continuous channel of 43-44
nucleotides length. Finally, an internal regulatory mechanism in the Ski2-Ski3-Ski8 complex was identi�ed. Both the Ski2-insertion domain and the Ski3 N-terminus cooperate to inhibit ATPase and helicase activity of Ski2 when bound in the SKI complex. Thus, the SKI complex regulates exosome activity in two ways. First by a direct substrate channeling mechanism to the exosome that connects helicase and nuclease activities of both complexes which may activate the exosome towards certain substrates. Second, by an inhibitory mechanism that regulates substrate access to the helicase complex, which is a prerequisite for controlling the exosome's substrate speci�city.
This doctoral thesis provides the �rst structural description of the entire yeast SKI complex and identi�es two mechanisms that may contribute to regulation of the activity of the cytoplasmic exosome.
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Halbach, Felix Verfasser], and Elena [Akademischer Betreuer] [Conti. "Structural and functional characterization of the yeast Ski2-Ski3-Ski8 complex / Felix Halbach. Betreuer: Elena Conti." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/1041584709/34.
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Pan, Wei. "Skin image processing and skin characterizations." Thesis, London South Bank University, 2017. http://researchopen.lsbu.ac.uk/1847/.
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The skin hydration and skin Trans epidermal water loss (TEWL) are of great importance in many skin research areas, such as dermatology, clinical analysis, pharmacology and cosmetic science etc. However, to measure them is not easy. Over the year , our research group has developed three novel technologies for such measurement : Opto Thermal Transient Emission Radiometry (OTTER), AquaFlux and capacitive contact imaging based on the Fingerprint sensor. The aim of this research is to develop new skin image processing and data analysis techniques for capacitive contact images, as well as digital colour images, and to develop new methodologies for skin characterization by using the three technologies. For skin image processing, a new GUI based MATLAB programme has been developed, which can be used for extracting and analysing the images from the result files created by the measurement instruments. The programme implement the skin image processing techniques such as image enhancement (i.e. brightness equalization, extraction of skin texture, hair removal), image stitching, image matching and skin surface 3D profiling etc. Another image processing programme based on OpenCV has also been developed, which is more suitable for real time video processing, including contour detection, texture extraction and face detection etc. For the skin characterization, several experiments are conducted: skin over hydration experiments; kin damage assessment including intensive washing, SLS irritations, and tape stripping; dermabrasion experiments; soap drying effect assessment. These experiments provide better understandings of the technologies. The occlusion effects in capacitive images shows good potential for skin damage assessment, as it can not only reflect the scale of damage, but also the types of damage.
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Kleismit, Richard A. "EVANESCENT MICROWAVE MICROSCOPY OF PORCINE SKIN TISSUE." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1221859953.
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Talbot, Jimmy D. "Accurate characterization of skin deformations using range data." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0007/MQ40751.pdf.
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Jenner, John. "The distribution and characterization of esterases in skin." Thesis, University of Surrey, 1986. http://epubs.surrey.ac.uk/847266/.
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1 - Two techniques of homogenising skin tissue have been examined for their efficiency to produce homogenates of rat skin containing subcellular organelles with the minimun amount of damage. 2 - The subcellular distribution of three hydrolase enzymes with catalytic activity towards, two esters of thiocholine and p-nitrophenylace tate, have been determined in the subcellular fractions produced from rat skin by homogenisation using grinding in liquid nitrogen. All three hydrolases were found to be solubilised by this technique and remained in the 100,000xg supernatant. 3 - The 100,000xg supernatant from rat skin was subject to molecular exclusion chromatography and the three solubilised hydrolases were followed through this procedure. Each of the hydrolase activities was found to be associated with a number of proteins that were different by molecular size. The two thiocholine ester hydrolases were associated with the same proteins, but the p-nitrophenylacetate hydrolase was predominantly associated with other proteins. 4 - The 100,000xg supernatant was also subjected to analysis of by polyacrylamide gel electrophoresis and staining with naphthylacetate. This procedure showed the presence of at least eight different hydrolases, and some of these electrophoretic bands could be associated with specific proteins of specific molecular size as determined by molecular exclusion chromatography. 5 - The hydrolases present in the 100,000xg supernatant from rat skin were characterised using four chromogenic substrates and four selective inhibitors. A cholinesterase with a substrate selectivity similar to that of acetylcholinesterase but an inhibitor selectivity similar to butyrylcholinesterase was found. Different esterases were responsible for the hydrolysis of p-nitrophenylacetate and indoxylacetate. 6 - The 100,000xg supernant from human skin was found to contain hydrolases that were different to those in rat skin. An enzyme hydrolysing p-nitrophenyl acetate that was insensitive to diisopropylfluorophosphate and did not hydrolyse this inhibitor was detected. The cholinesterase present behaved in the same way as butyrylcholinesterase. Only one electrophoretic band of naphthylacetate hydrolysing activity could be detected by polyacrylamide gel electrophoresis. 7 - Naphthylacetate and 5-bromoindoxylacetate hydrolases were histochemically located in skin from rat and man.
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O'Brien, Daniel P. "Characterization and Modeling of the In Vivo Mechanical Response of Human Skin Using Handheld Devices." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1337715574.
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Raju, Balasundara I. (Balasundara Iyyavu) 1972. "High frequency ultrasonic characterization of human skin In vivo." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/29232.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 144-161).
High frequency (>20 MHz) ultrasound has numerous potential applications in dermatology because of its ability to penetrate several millimeters into the skin and provide information at a spatial resolution of tens of microns. However, conventional B-scan images of skin tissues often lack the capability to characterize and differentiate various skin tissues. In this work, quantitative ultrasonic methods using the attenuation coefficient, backscatter coefficient, and echo envelope statistics were studied for their potential to characterize human skin tissues in vivo. A high frequency ultrasound system was developed using polymer transducers, a pulser/receiver, high-speed digitizer, 3-axis scanning system, and a PC. Data collected using three different transducers with center frequencies of 28, 30 and 44 MHz were processed to determine the characteristics of normal human dermis and subcutaneous fat. Attenuation coefficients were obtained by computing spectral slopes vs. depth, with the transducers axially translated to minimize diffraction effects. Backscatter coefficients were obtained by compensating recorded backscatter spectra for system-dependent effects, and additionally for one transducer, using the reference phantom technique. Good agreement was seen between the results from the different transducers/methods. The attenuation coefficients were well described by a linear frequency dependence whose slope showed significant differences between the forearm and fingertip dermis, but not between the forearm dermis and fat. The backscatter coefficient of the dermis showed an increasing trend with frequency and was significantly higher than that of fat.
(cont.) A maximum likelihood fit of six probability distributions (Rayleigh, Rician, K, Nakagami, Weibull, and Generalized Gamma) to fluctuations in echo envelope data showed that the Generalized Gamma distribution modeled the envelope better than the other distributions. Fat was seen to exhibit significantly more pre-Rayleigh behavior than the dermis. Data were also obtained from the skin of patients patch-tested for contact dermatitis. A significant increase in skin thickness, decrease in mean backscatter of the upper dermis, and decrease in attenuation coefficient slope was found at the affected sites compared to normal skin. However, no differences in terms of echo statistics were found in the mid-dermis. These results indicate that a combination of ultrasonic parameters have the potential to non-invasively characterize skin tissues.
by Balasundara I. Raju.
Ph.D.
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Narayanaswamy, Variankaval. "Characterization of phase transitions in transdermal drug delivery systems." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/8645.
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Jones, Elizabeth Louise. "Characterization of IL-1-stimulated phosphorylation in human epidermal carcinoma cells." Thesis, Open University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357978.
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Kim, Youngsoo. "Molecular characterization of cyclooxygenase-2 (COX-2) expression in murine skin carcinoma cells /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Gherardi, Alessandro <1971>. "A skin surface characterization system based on capacitive image analysis." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/1135/.
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During the last few years, several methods have been proposed in order to study and to
evaluate characteristic properties of the human skin by using non-invasive approaches. Mostly,
these methods cover aspects related to either dermatology, to analyze skin physiology and to
evaluate the effectiveness of medical treatments in skin diseases, or dermocosmetics and
cosmetic science to evaluate, for example, the effectiveness of anti-aging treatments. To these
purposes a routine approach must be followed. Although very accurate and high resolution
measurements can be achieved by using conventional methods, such as optical or mechanical
profilometry for example, their use is quite limited primarily to the high cost of the instrumentation
required, which in turn is usually cumbersome, highlighting some of the limitations for a routine
based analysis.
This thesis aims to investigate the feasibility of a noninvasive skin characterization
system based on the analysis of capacitive images of the skin surface. The system relies on a
CMOS portable capacitive device which gives 50 micron/pixel resolution capacitance map of the
skin micro-relief. In order to extract characteristic features of the skin topography, image analysis
techniques, such as watershed segmentation and wavelet analysis, have been used to detect the
main structures of interest: wrinkles and plateau of the typical micro-relief pattern. In order to
validate the method, the features extracted from a dataset of skin capacitive images acquired
during dermatological examinations of a healthy group of volunteers have been compared with
the age of the subjects involved, showing good correlation with the skin ageing effect. Detailed
analysis of the output of the capacitive sensor compared with optical profilometry of silicone
replica of the same skin area has revealed potentiality and some limitations of this technology.
Also, applications to follow-up studies, as needed to objectively evaluate the effectiveness of
treatments in a routine manner, are discussed.
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Robic, Julie. "Automated characterization of skin aging using in vivo confocal microscopy." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1069/document.
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La microscopie confocale de réflectance in-vivo (RCM) est un outil puissant pour visualiser les couches cutanées à une résolution cellulaire. Des descripteurs du vieillissement cutané ont été mis en évidence à partir d'images confocales. Cependant, leur évaluation nécessite une analyse visuelle des images par des dermatologues expérimentés. L'objectif de cette thèse est le développement d'une technologie innovante pour quantifier automatiquement le phénomène du vieillissement cutané en utilisant la microscopie confocale de réflectance in vivo. Premièrement, la quantification de l’état de l’épiderme est abordée. Ensuite, la jonction dermique-épidermique est segmentée, et sa forme est caractérisée. Les mesures proposées mettent en évidence une différence significative entre les groupes d'âge et l’exposition au soleil. Enfin, les méthodes proposées sont validées par des études cliniques et d'efficacité de produits cosmétiquesIn-vivo reflectance confocal microscopy (RCM) is a powerful tool to visualize the skin layers at cellular resolution. Aging descriptors have been highlighted from confocal images. However, it requires visual assessment of images by experienced dermatologists to assess those descriptors. The objective of this thesis is the development of an innovative technology to automatically quantify the phenomenon of skin aging using in vivo reflectance confocal microscopy. First, the quantification of the epidermal state is addressed. Then, the Dermal-Epidermal Junction is segmented, and its shape is characterized. The proposed measurements show significant difference among groups of age and photo-exposition. Finally, the proposed methods are validated through both clinical and cosmetic product efficacy studies
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Conroy, Eileen M. "SPATIAL AND TEMPORAL CHARACTERIZATION OF SKIN TREATMENT PRODUCT DISTRIBUTION ON THE SKIN USING FLORESCENT STEREOMICROSCOPIC IMAGING." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin976027198.
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Selzer, Dominik [Verfasser], and Ulrich F. [Akademischer Betreuer] Schäfer. "Mathematical characterization of skin absorption / Dominik Selzer. Betreuer: Ulrich F. Schäfer." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2016. http://d-nb.info/1090875673/34.
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Saavedra, Bazán Ana Cecilia. "Characterization of healthy skin with high-frequency ultrasound using quantitative ultrasound." Master's thesis, Pontificia Universidad Católica del Perú, 2018. http://tesis.pucp.edu.pe/repositorio/handle/123456789/12471.
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The skin is the largest organ of the body that protects it from the external environment. High- frequency ultra sound (HF-US) has been used to visualize the skin in depth and to diagnose some pathologies in dermatological applications. Quantitative ultrasound (QUS) includes several techniques that provide values of particular physical properties. In this thesis work, three QUS parameters are explained and used to characterize healthy skin through HF-US: attenuation coefficient slope (ACS), backscatter coefficient (BSC) and shear wave speed (SWS). They were estimated with the regularized spectral-log difference (RSLD) method, the reference phan- tom method, and the crawling wave sonoelastography method, respectively. All the three parameters were assessed in phantoms, ex vivo and in vivo skin. In calibrated phantoms, RSLD showed a reduc- tion of up to 93% of the standard deviation concerning the estimation with SLD, and BSC showed an agreement with the Faran’s theoretical curve. In gelatin-based phantoms, surface acoustic waves (SAWs) were estimated in two interfaces: solid-water and solid-US gel, which all owed corroborating SAWs presence and finding an empirical compensation factor when the coupling interface is US gel. A correction factor of 0:97 for SAW-to-shear was found to avoid underestimation in phantoms. Porcine thigh was calculated in the range from 8 to 27 MHz, where the ACS was 4:08 _+_0:43 dB cm -1 MHz-1 and BSC was in the range from 10 1 to 10° sr-1 _cm-1. Crawling wave sonoelastography method was applied for the vibration frequencies between 200 Hz and 800 Hz, where SWS was in the range from 4:6 m/sto9:1 m/s. In vivo ACS and BSC were assessed in the healthy forearm and thigh, whereas SWS only in the thigh. The average ACS in the forearm dermis was 2.07dB cm-1 _MHz-1, which is in close agreement with the literature. A significant difference (p < 0.05) was found between the ACS in the forearm dermis and the thigh dermis (average ACS of 2.54dB cm-1 _MHz-1). The BSC of the forearm and thigh dermis were in the range from 10 -1 to 10° sr-1 _cm-1, and in the range from 10-1 to 10° sr-1 _cm-1, respectively. The SWS in the thigh dermis was 2:4 _+_0:38 m/s for a vibration frequency of 200Hz, with an increasing trend as frequency increases. Results suggest that these QUS parameters have the potential to be used as a tool for in vivo skin characterization and show potential for future application in skin lesions.Tesis
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Anxionnat, Adrien. "Segmentation of high frequency 3D ultrasound images for skin disease characterization." Thesis, KTH, Teknisk informationsvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209203.
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This work is rooted in a need for dermatologists to explore skin characteristicsin depth. The inuence of skin disease such as acne in dermal tissues is stilla complex task to assess. Among the possibilities, high frequency ultrasoundimaging is a paradigm shift to probe and characterizes upper and deep dermis.For this purpose, a cohort of 58 high-frequency 3D images has been acquiredby the French laboratory Pierre Fabre in order to study acne vulgaris disease.This common skin disorder is a societal challenge and burden aecting late adolescentsacross the world. The medical protocol developed by Pierre Fabre wasto screen a lesion every day during 9 days for dierent patients with ultrasoundimaging. The provided data features skin epidermis and dermis structure witha fantastic resolution. The strategy we led to study these data can be explainedin three steps. First, epidermis surface is detected among artifacts and noisethanks to a robust level-set algorithm. Secondly, acne spots are located on theresulting height map and associated to each other among the data by computingand thresholding a local variance. And eventually potential inammatorydermal cavities related to each lesion are geometrically and statistically characterizedin order to assess the evolution of the disease. The results presentan automatic algorithm which permits dermatologists to screen acne vulgarislesions and to characterize them in a complete data set. It can hence be a powerfultoolbox to assess the eciency of a treatment.Detta arbete är grundat i en dermatologs behov att undersöka hudens egenskaperpå djupet. Påverkan av hudsjukdomar så som acne på dermala vävanderär fortfarande svårt att bedöma. Bland möjligheterna är högfrekvent ultraljudsavbildningett paradigmskifte för undersökning och karakterisering av övre ochdjupa dermis. I detta syfte har en kohort av 58 högfrekventa 3D bilder förvärvatsav det Franska laboratoriet Pierre Fabre för att studera sjukdomen acne vulgaris.Denna vanliga hudsjukdom är en utmaning för samhället och en bördasom påverkar de i slutet av tonåren över hela världen. Protokollet utvecklatav Pierre Fabre innebar att undersöka en lesion varje dag över 9 dagar förolika patienter med ultraljudavbildning. Den insamlade datan visar hudens epidermisoch dermis struktur med en fantastiskt hög upplösning. Strategin vianvände för att studera denna data kan förklaras i tre steg. För det första,hittas epidermis yta bland artifakter och brus tack vare en robust level-set algoritm.För det andra, acne äckar hittas på höjdkartan och associeras tillvarandra bland mätdatan genom en tröskeljämförelse över lokala variationer.Även potentiellt inammatoriska dermala hålrum relaterade till varje lesion blirgeometriskt ochj statistiskt kännetecknade för att bedöma sjukdomens förlopp.Resultaten framför en automatisk algoritm som gör det möjligt för dermatologeratt undersöka acne vulgaris lesioner och utmärka de i ett dataset. Detta kandärmed vara en kraftfull verktygslåda för att undersöka inverkan av en behandlingtill denna sjukdom.
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Van, Staden Anton Du Preez. "In vitro and In vivo characterization of Amyloliquecidin, a novel two-component lantibiotic produced by Bacillus amyloliquefaciens." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96656.
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Thesis (PhD)--Stellenbosch University, 2015.ENGLISH ABSTRACT: Antimicrobial resistance is one of the major problems faced by the medical industry today. The ability of bacteria to rapidly acquire resistance against antibiotics and the over prescription and inappropriate use of antibiotics further exacerbate this crisis. Few new antimicrobials are, however, making it through the drug discovery pipeline. The search and development of novel and effective antimicrobials is therefore of the utmost importance. Lantibiotics are ribosomally synthesized cationic antimicrobial peptides with extensive post-translational modifications. They are active against a wide range of Gram-positive bacteria, including antibiotic-resistant strains. They are characterized by the presence of lanthionine and methyllanthionine rings and have been suggested as alternatives or for use in conjunction with antibiotics against resistant pathogens. Staphylococcus aureus is the most common bacteria isolated from skin and soft tissue infections (SSTIs). Strains of S. aureus have emerged with resistance against antibiotics with the most common being methicillin-resistant S. aureus (MRSA). Several lantibiotics are active against MRSA in vivo and have even shown superior activity to traditional antibiotics. Lantibiotics therefore show much promise for the treatment of SSTIs caused by resistant- and non-resistant S. aureus. In this study the bacterially diverse soil of the Fynbos in the Western Cape was screened for novel antimicrobials. Two antimicrobial producing Bacillus strains were isolated, Bacillus clausii AD1 and Bacillus amyloliquefaciens AD2. Both of these strains produce lantibiotics with B. clausii AD1 producing a known lantibiotic, clausin. B. amyloliquefaciens AD2 produces a novel two-component lantibiotic which was designated amyloliquecidin. The lantibiotic operon of amyloliquecidin was sequenced and annotated. All the genes required for successful production of amyloliquecidin are present in the operon. Amyloliquecidin was characterized in vitro and along with clausin is active against clinical strains of S. aureus (including MRSA), Enterococcus spp., Listeria spp. and beta-haemolytic streptococci. Amyloliquecidin has remarkable stability at physiological pH compared to nisin and clausin. A comparative in vivo murine infection model was used to evaluate the effectiveness of amyloliquecidin, nisin, clausin and Bactroban (commercial S. aureus topical treatment) in treating wound infections caused by S. aureus. All the lantibiotics proved to be just as effective as the Bactroban treatment. Furthermore, the tested lantibiotics did not have a negative influence on the wound closure rates of infected and non-infected wounds. Bactroban had a negative effect on wound healing compared to the lantibiotics. To our knowledge amyloliquecidin is the third two-component lantibiotic isolated from Bacillus. This study represents the first to test the effectiveness of amyloliquecidin in vivo and is one of a handful to test lantibiotics as topical treatments.
AFRIKAANSE OPSOMMING: Antimikrobiese weerstandbiedende bakterieë is op die oomblik een van die grootste probleme in die mediese veld. Die antibiotika krisis word vererg deur die vermoë van bakterieë om vinnig weerstand op te bou teen antibiotika, asook die alledaagse misbruik van antibiotika. Daar is ook ʼn tekort in die hoeveelheid antibiotika wat na die finale fases van ontwikkeling gaan. Om die oorhand teen antibiotika-weerstandige bakterieë te kry is dit van uiterste belang dat meer effektiewe antibiotika ontdek word. Lantibiotika is kationiese antimikrobiese peptiede wat deur die ribosoom gesintetiseer word en bevat ʼn verskeidenheid van modifikasies wat na translasie ingebou word. Hulle word gekarakteriseer deur lanthionien en metiellanthionien ringe. Lantibiotika is aktief teen ʼn verskeidenheid Gram-positiewe bakterieë en kan in kombinasie met antibiotika, of as alternatief gebruik word. Staphylococcus aureus is die mees algemene bakterium wat geassosieer word met vel en sagte weefsel infeksies (VSWIs). Staphylococcus aureus met weerstand teen antibiotika is ook al geïsoleer, die mees algemene weerstandige ras is methisillien-weerstandige S. aureus (MWSA). Lantibiotika is wel aktief teen MWSA in vitro en in vivo, met van hulle wat tot beter aktiwiteit as die voorgeskrewe antibiotika het. Lantibiotika kan dus gebruik word as behandeling vir VSWIs wat veroorsaak word deur weerstandige S. aureus, asook teen nie-weerstandige rasse. In hierdie studie was die bakteriese diverse grond van die Fynbos in die Wes-kaap ondersoek vir bakterieë wat antimikrobiese middels produseer. Twee Bacillus rasse, Bacillus clausii AD1 en Bacillus amyloliquefaciens AD2, wat antimikrobiese middels produseer, is geïsoleer. Bacillus clausii AD1 produseer ʼn bekende lantibiotikum, naamlik clausin. Bacillus amyloliquefaciens AD2 produseer ʼn nuwe twee-komponent lantibiotikum, amyloliquecidin. Die lantibiotikum operon wat verantwoordelik is vir die produksie van amyloliquecidin is geïdentifiseer en geannoteer. Die operon bevat al die gene benodig vir die biosintese van amyloliquecidin. Amyloliquecidin is in vitro gekarakteriseer en het aktiwiteit teen ʼn verskeidenheid Gram-positiewe bakterieë. Amyloliquecidin en clausin is aktief teen S. aureus (insluitend MWSA), Enterococcus spp., Listeria spp. en beta-hemolitiese streptococci wat vanaf infeksies geïsoleer is. Amyloliquecidin is baie stabiel by filologiese pH en aansienlik meer stabiel as nisin en clausin. Die effektiwiteit van nisin, clausin en amyloliquecidin in die behandeling van muis vel infeksies veroorsaak deur S. aureus was vergelyk met die kommersiële behandeling Bactroban. Al drie lantibiotika het die verspreiding van S. aureus met die selfde effektiwiteit as Bactroban belemmer. Geen van die lantibiotika het ʼn negatiewe effek op wond genesing nie. Bactroban, inteendeel, belemmer wond genesing. So ver ons weet is amyloliquecidin die derde twee-komponent lantibiotikum wat uit Bacillus geïsoleer is. Die studie is ook die eerste om die effektiwiteit van amyloliquecidin in vivo te rapporteer, asook ook een van die min studies wat kyk na lantibiotika as behandeling vir topikale infeksies.
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Wu, Xiao. "Characterization and evaluation of novel nano/meso-particulate formulations for application to the skin." Thesis, University of Bath, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501631.
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The use of nano/meso-particles (NP/MP) as constituent of topical formulations of drug and cosmetics has been a topic of considerable interest for the past 20 years. However, the transport mechanism of nanoparticle-associated drug/active following topical application on the skin is still unclear. No general answers have been obtained to such questions as the depth of intact NP penetration into the skin, the skin distribution of active substances, and the fate of the vehicles on/in the skin. The main objective of this thesis, therefore, was to observe the in vitro penetration of fluorescently-labeled nanoparticle vehicle and “active” on/within the skin by using laser scanning confocal microscopy (LSCM). Furthermore, the concentration profile of the “active” in the outermost skin layer, stratum corneum, has been assessed by using tape stripping technique combined with HPLC analysis. The factors, including particle size, hydrophobicity, shell thickness of nanocapsules and surface charge, have been investigated with regard to their abilities to influence the penetration of “active” into the skin. The methods for NP preparation and characterization have also been developed. The results demonstrated that the delivery of “active” into the stratum corneum from NP/MP were influenced by a number a factors, including particle size, hydrophobicity, surface charge and shell thickness of capsules. The “active” delivery (i) is greater from larger vectors; (ii) increases as the hydrophobicity of NP/MP increases; (iii) is favoured by cationic NP; (iv) is favoured from capsules with a smaller shell thickness. NP vehicle and “active” mainly co-localize in skin “furrows” and around hair follicles after topical application. No evidence shows NP penetrate beyond the superficial layer of the skin. In the stratum corneum, the “active” remains in part associated with NP, but the release f the “active” clearly occurs to some extent followed by its penetration into deep layers of the stratum corneum. Overall, through this work, the fate of nanoparticle vehicle and the “active” has been distinguished and the physicochemical properties of the nanoparticles that determine their behaviour once applied to the skin, and the kinetics with which an “active” is released, has also been understood.
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Gangnuss, Samantha. "Characterization of AP-1 transcription factor activation by wounding in fetal skin." Title page, table of contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phg1974.pdf.
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"June 2002" Bibliography: leaves 144-170. Fetal skin has a unique ability to re-epithelialize a wound in the absence of dermal substrata, although this capacity is lost between embryonic day 17 (E17) and day 19 of gestation (E19) in the rat. This study seeks to identify the molecular signalling events induced by wounding in E17 and E19 skin, as well as the role these events play in the prenatal switch in re-epithelialization mechanisms in fetal skin.
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Kringle, Amy. "Separation and Characterization of Reconstituted Skim Milk Powder Treated with Mineral Chelators." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1556.
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The proteins found in milk are largely important in the functionality of many dairy products and dairy processes. The casein micelle system in milk is a complex and highly studied system. The micelle is thought to be a sponge like structure containing four caseins, αs1, αs2, β, and κ casein, and bound together with colloidal calcium phosphate. When a chelating agent such as a citrate, phosphate, or polyphosphate are added to milk systems, the CCP is bound to the chelator and removed from the micelle. It has been shown through past research that the use of calcium chelating agents disrupts the calcium phosphate equilibrium and allows for the dissociation of the casein micelle and release of the individual caseins. Once the caseins are disrupted from micellar form and in solution, it may be possible to separate out different casein streams for functional usage in dairy products using common separation techniques.
This thesis project seeks to evaluate the feasibility of separating milk treated with calcium chelators using various separation techniques to evaluate the individual casein fractions of this disrupted system. Four separation methods (ultracentrifugation, membrane filtration, heat coagulation, and coagulation based on pH) were employed to separate out the caseins based on selected properties, specifically density, molecular weight, and solubility. In ultracentrifugation, three speeds were tested, the heat coagulation study tested two temperatures, and pH based coagulation tested four different pHs to determine their impact on overall protein levels and individual casein yields. Skim milk powder was reconstituted and chelator was added at 1, 50, or 100 mEq/L treatment level. These samples were then separated using aforementioned techniques, and the supernatant or permeate was analyzed for total protein content, individual casein composition, turbidity, and mean particle size.
Analysis of centrifugal separation studies shows the interaction between chelator type, chelator level, and centrifugation speed had a significant impact on the amount of protein released from the casein micelle (p
Coagulation trials based on pH were also shown to have a significant interaction between chelator type, chelator level, and sample pH effecting the protein levels and casein composition (p
Membrane filtration showed low protein yields in permeate, however trisodium citrate 100 mEq was still shown to have significantly higher permeate % protein levels (p
The use of heat based coagulation as an individual casein separation technique for chelated samples is not recommended, as the casein micelle system itself is extremely heat stable, and the use of calcium chelators only increases the heat stability further. Because of the increased heat stability, no coagulum was formed in samples upon heating, and therefore, no separation and analysis could be done.
Improving our knowledge of pretreatment of milk prior to separation and the effectiveness of different separation methods on chelated milk products may result in information leading to the ability to separate out milk fractions that provide unique or improved properties for product applications.
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LaTorre, Carmen Anthony. "Nanotribological characterization of human hair and skin using Atomic Force Microscopy (AFM)." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1413372982.
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Lieto, Louis D. "Characterization of Epitheliogenesis Imperfecta in Equus caballus." UKnowledge, 2001. http://uknowledge.uky.edu/gradschool_diss/475.
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Epitheliogenesis Imperfecta (EI) is a mechanobullous disease that occurs in newborn American Saddlebred and Belgian Draft foals. Necropsy evaluations of two American Saddlebred foals revealed broad skin lesions, dental abnormalities and oral mucosa lesions. Construction of a partial pedigree showing occurrences of EI in American Saddlebred horses was consistent with a recessive pattern of inheritance. An allelic frequency of 0.04 was estimated for the EI gene. The pathological signs of EI were similar to a disease in humans known as Herlitz Junctional Epidermolysis Bullosa (HJEB). HJEB is caused by a defect in one of the three subunits of the laminin 5 protein (LAM 3, LAM 3 and LAM 2), which leads to a separation of the epidermis from the dermis. Transmission electron microscopy revealed a separation within the lamina lucida at the sites of epidermal/dermal splits in the skin of EI affected foals. This indicated that a defect in the laminin 5 protein was responsible for EI. Linkage disequilibrium (LD) between microsatellite markers and the EI disease locus was tested for in the American Saddlebred and Belgian Draft breeds. Genotyping of microsatellite alleles was used to determine fit to Hardy-Weinberg equilibrium for control and EI populations for both breeds using Chi square analysis. Two microsatellite loci (ASB14 and AHT3) were not in Hardy-Weinberg equilibrium in EI affected American Saddlebred horses. This suggested that the EI disease locus was located on ECA 8, the putative location of LAM 3. No evidence of LD between any of the tested microsatellite loci and the EI locus was observed in the Belgian Draft samples. A cDNA library was built from Thoroughbred horse skin to serve as a resource for sequencing equine skin gene transcripts. 313 ESTs were sequenced, of which 207 were putatively identified (66%) by database search. Examination of the pathology and ultrastructure of EI affected foals and comparison with HJEB indicated that laminin 5 was the responsible defective protein. The LD analysis suggested that LAM 3 was the EI disease locus in American Saddlebred horses.
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JOSEPH, WAEL. "PHYSICAL CHARACTERIZATION OF VERNIX CASEOSA: IMPLICATIONS FOR BIOLOGICAL FUNCTION." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1022624142.
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Wang, Hequn. "Multimodality microscopy and micro-Raman spectroscopy for in vivo skin characterization and diagnosis." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44206.
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Cipriano, Jordi. "Energy characterization and experimental validation of natural ventilated semitransparent double skin PV components." Doctoral thesis, Universitat de Lleida, 2014. http://hdl.handle.net/10803/286038.
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Els sistemes integrats Fotovoltaics (FV) de doble pell, són components de l'edifici que combinen les funcions d'envolvent, amb les d'il·luminació natural, generació d'electricitat i generació d'energia tèrmica. La modelització dels processos de transferència d'energia d'aquests components, especialment en situacions de convecció natural, planteja una alta complexitat i és un dels inconvenients principals per a una disseminació massiva d'aquesta tecnologia. En les últimes dècades s'han dut a terme diferents intents per a superar aquest inconvenient i s'han desenvolupat diferents models de simulació. No obstant això, molt pocs estudis s'han enfrontat a una anàlisi detallat del rang de validesa d'aquestes correlacions i models i tampoc de les limitacions inherents en la seva definició. El segon inconvenient per a una àmplia propagació d'aquests components FV complexos, està relacionat amb la dificultat per a dur a terme campanyes experimentals de mesura del seu comportament energètic en condicions reals. A més dels mencionats inconvenients, s'hi afegeix una gran manca de coneixement per a la cal·libració dels models de simulació de components FV ventilats. Aquesta tesi doctoral aborda aquests inconvenients i introdueix una metodologia general per a la caracterització energètica i la validació experimental dels components FV ventilats. Aquesta investigació també contribueix a augmentar el coneixement sobre mètodes per a integrar el desenvolupament de models de simulació dinàmica, amb enfocaments innovadors per a la seva cal·libració.Los sistemas integrados Fotovoltaicos (FV) de doble piel, son components del edificio que combinan las funciones de envolvente, con las de illuminación natural, generación eléctrica y generación de energía térmica. La modelización de los procesos de transferència de energía de estos components, especialmente en situaciones de convección natural, plantea una alta complejidad y es uno de los inconvenientes principales para una diseminación masiva de esta tecnología. En las últimas décadas, se han llevado a cabo diferentes intentos para a superar este inconveniente y se han desarrollado diferentes modelos de simulación para evaluar la eficiéncia energética global de estos sistemas. Sin embargo, muy pocos estudios se han enfrentado al análisis detallado del rango de validez de estas correlaciones y modelos y tampoco de las limitaciones inherentes en su definición. El segundo inconvenient para una amplia propagación de estos components FV complejos, está relacionado con la dificultad para llevar a cabo campañas experimentales de medida de su comportamento energético en condiciones reales. Además de estos inconvenientes, se constata una carencia significativa de conocimiento sobre métodos para la calibración de los modelos de simulación de componentes FV ventilados . Esta tesis doctoral aborda todos estos inconvenientes mencionados anteriormente e introduce una metodología general para la caracterización energética y la validación experimental de los componentes FV ventilados. Esta investigación también contribuye a aumentar el conocimiento sobre métodos para integrar el desarrollo de modelos de simulación dinámica, con estrategias innovadoras para su calibración.
Double skin semi transparent components with Photovoltaic integrated systems are building components which combine functions of the building envelope with natural lighting, electricity and thermal energy generation. The energy transfer modeling of these components, especially under free convection situations, raises a high complexity and is the first main drawback for a massive dissemination of this technology. Many attempts to fill this gap have been undertaken and some dynamic simulation models of these components have been obtained in the last decades. However, very few studies have faced a detailed analysis of the valid range of these mathematical expressions and simulation models and of the restrictions entailed. The second drawback for a wide spread of these complex PV components is related to the difficulty in setting up monitoring and experimental campaigns to measure their real energy performance with sufficient accuracy and precision. Besides these drawbacks, there is also a lack of knowledge on methods for calibrating building energy simulation models in general, and specifically in the calibration of dynamic models of ventilated PV components. This PhD thesis addresses these existing drawbacks and introduces an overall methodology for the energy characterization and experimental validation of ventilated PV components. This research also contributes in increasing the knowledge on methods for coupling the mathematical development of dynamic simulation models with innovative approaches for its calibration with experimental measures.
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Hou, Lin. "The distribution and characterization of protease-activated receptors in oral mucosa and skin." Thesis, Queen Mary, University of London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286544.
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Duconseille, Anne. "Molecular and structural characterization of pig skin gelatin : impact on its dissolution quality." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22737.
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Malgré un large éventail d'applications de la gélatine et en dépit de son utilisation très ancienne, sa composition et sa structure ne sont pas encore entièrement connues et comprises. La gélatine est obtenue à partir de tissus animaux (peaux ou os) et est le résultat de l'hydrolyse partielle du collagène. La production de gélatine la plus abondante est celle de peau de porc qui représentait 46% de la production totale en 2007. Parmi les nombreuses applications, la gélatine de peau de porc est utilisée comme ingrédient principal des gélules dures pour l'industrie pharmaceutique. Une propriété importante de ces gélules est qu'elles fondent dans l'eau à une température au-dessus de 30° C et libèrent facilement les médicaments qu’elles contiennent dans le tube digestif. Les gélules dures doivent répondre à des spécifications de dissolution strictes tout au long de leur durée de conservation d'environ cinq ans. Ainsi, un test de dissolution dans l'eau est appliqué à la gélatine artificiellement vieillie dans des conditions de température et d'humidité élevées. Bien qu'avant le vieillissement le taux de dissolution de la gélatine corresponde toujours aux besoins de l'industrie pharmaceutique, une grande variabilité du taux de dissolution est observée après vieillissement. De plus, cette variabilité de dissolution dépend de l'origine de production de la gélatine. Dans ce contexte, un premier objectif était de comprendre les mécanismes sous-jacents impliqués dans la variabilité de la qualité de dissolution de la gélatine de peau de porc. Un deuxième objectif était d'identifier d'éventuels "marqueurs" de la dissolution de la gélatine afin de prédire son comportement au cours du vieillissement. Trois différents sites de production ont été choisis: deux en Europe et un aux USA. Au cours du vieillissement, la formation de cross-links a été mise en évidence et parmi ces cross-links, la dityrosine a été identifiée comme marqueur du vieillissement. En outre, les taux d'amines et d'aldéhydes ont diminué. Etant donné que ces deux fonctions sont connues pour réagir ensemble; ce résultat suggère qu'elles pourraient former d'autres cross-links au cours du vieillissement. Le processus d'oxydation dans la gélatine a été clairement démontré. De plus, la quantité de triple-hélices et leur stabilité au chauffage ont diminué alors que la quantité de conformation aléatoire et, probablement, de boucles-β augmente. Les résultats ont mis en évidence que l'origine de production affecte la composition chimique de la gélatine. Par exemple, la quantité de cross-links formés, comme la dityrosine, dans les gélatines fraîches et vieillies, différait selon l'origine de production. Nous avons également pu souligner que l'environnement physico-chimique de l'arginine permettait de distinguer l'origine de production de la gélatine. En ce qui concerne la dissolution de la gélatine, celles présentant des taux de dissolution non conformes avaient plus de phase amorphe après vieillissement que les gélatines conformes. L'implication des lipides dans la diminution de la dissolution de la gélatine a également été mise en évidence. La haute teneur en fer était également liée à la diminution de la dissolution mais seulement dans un site de production, ce qui suggère que la variabilité de dissolution a probablement des causes multifactorielles et dépendantes de l'origine de production.Avec le dichroïsme circulaire, nous avons pu discriminer les gélatines conformes des non-conformes avant même le vieillissement de ces gélatines. Cependant, l'interprétation des résultats reste très difficile en raison du manque d'information dans la littérature. Un tel résultat est important pour prédire le comportement de la gélatine avant le vieillissement. De manière générale, nos résultats ont mis en évidence qu’il serait pertinent de contrôler et de réduire le niveau d'oxydation et la teneur en lipides de la gélatine pour diminuer sa variabilité de dissolution. (...)Despite a wide range of applications of gelatin and despite its very former use, gelatin composition and structure remains not fully known and understood. It is derived from animal tissue (skins or bones) and is the result of partial hydrolysis of collagen. The most abundant gelatin production, which is the focus of the present work, is pig skin gelatin which represented 46% of total production in 2007. Among numerous applications, gelatin is used as the main ingredient of the hard capsules for the pharmaceutical industry. An important property of hard capsules is that they melt in water at a temperature above 30°C and easily release drugs in the human digestive tract. Hard capsules have to meet strict dissolution specifications all along a shelf life of about five years. Thus, a dissolution test in water is applied to the gelatin constituting the hard capsules, after being artificially aged under high temperature and humidity conditions. While before aging the dissolution rate of gelatin always fit with requirement of pharmaceutical industry, a high variability in dissolution rate is observed after aging. Moreover, this dissolution variability was shown depending on the gelatin origin of production. In this context, a first objective of this work was to understand the underlying mechanisms involved in the variability of the dissolution quality of pig skin gelatin. A second objective was to identify possible “markers” of gelatin dissolution in order to predict the behaviour of gelatin through aging. Three different sites of production were chosen: two in Europe and one in USA. Cross-links formation was evidenced during aging, and among them, dityrosine was expressly identified as a marker of aging. In addition the levels of amines and aldehydes were decreased. Given that these two functions could react together; this result suggests that they could form other cross-links. Oxidation process in gelatin was clearly demonstrated. Furthermore, the quantity of triple-helices and their stability to heating decreased while the quantity of random coil and, probably, β-turns conformations increased. The results highlighted that origin of production impacts the chemical composition of gelatin. For instance, the extent of cross-link formation, such as dityrosine, in both fresh and aged gelatins, differed according to the origin of production. It was also pointed out that the physico-chemical environment of arginine allowed the distinction of production origin of gelatin. Regarding the gelatin dissolution, those showing non-compliant dissolution rates exhibited higher content of amorphous phase after aging than compliant ones. The implication of lipids in the decrease of gelatin dissolution rate was also evidenced. The decrease in dissolution was linked to the iron content only in one production site supporting the fact that dissolution variability has probably multifactorial causes, depending on the origin of production. The compliant and non-compliant dissolution rates were discriminate even before aging of gelatins by circular dichroism. However, the results interpretation remains quite difficult due to lack of literature information.Such a result is of importance in a view of predicting the behavior of gelatin before aging. To display a general overview, our results highlighted that, in order to reduce variability in the dissolution of gelatin, controlling and reducing the oxidation level and the lipid content will be relevant levers. To study the structural conformation thoroughgoing small angles neutrons would be an interesting tool. To complete the characterization of gelatin composition, quantifying and profiling lipids and sugars would be useful to better understand the gelatin oxidative instability
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Johnson, Jacqueline M. "Structural and Biochemical Characterization of the Frequency-Interacting RNA Helicase FRH." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/4678.
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RNA is a molecular messenger of the cell, essential to many cellular pathways and processes. In order to maintain functionality, RNA is processed and modified by protein complexes such as the exosome and associated proteins. The exosome-mediated RNA processing or degradation both require a Ski-2 like helicase to function. One such helicase is the Frequency-interacting RNA Helicase (FRH), an essential RNA helicase from Neurospora Crassa. FRH is homologous to the Saccharomyces cerevisiae Mtr4 from the Ski2-like family of RNA helicases. Sequence alignments between FRH and Ski2-like family helicases predicted FRH to share the helicase core domains and the inserted arch domain a characteristic of the Mtr4-like proteins in this protein family. FRH is also a main component of the circadian oscillation pathway in N. crassa. The participation of FRH in circadian oscillation is not a shared role across RNA helicases. FRH forms a link between two major cellular pathways providing a unique system to study RNA surveillance. Here we present the 3.51Å and 3.25Å crystal structures of FRH which supports structural prediction by maintaining the core architecture found in Ski2-like helicases. These similarities are accompanied by significant flexibility of the arch domain and revealed a unique homodimer. Other known Ski2-like helicases have not been observed to form dimers and function biologically as monomers. Furthermore, the initial characterization of helicase activity of FRH on a poly-adenylated RNA substrate is presented. Also explored is the evidence of a dimer through crosslinking and size exclusion chromatography assays.
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Stiles, Bangyan Li. "Keratinocyte secretory phospholipase A₂s : its characterization, modulation, and role in mouse skin carcinogenesis /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Popoola, Olugbenga Kayode. "The chemical and biological characterization of South African helichrysum species." University of the Western Cape, 2015. http://hdl.handle.net/11394/4702.
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Philosophiae Doctor - PhDSouth Africa has immensely rich natural flora diversity with more than 20 000 species of higherplants. Asteraceae is one of the biggest families of flowering plants with about 246 genera and 2,300 species in southern Africa. South Africa being home to more than 35 % of the world's Helichrysum species (c.a. 244) of which many are used in traditional medicine, and can be considered as a potential resource for new bioactive chemical entities. Chemical studies on the total extract of the South African Helichrysum species viz: H. teretifolium, H. niveum and H. rutilans resulted in the isolation of twenty eight [14 flavonoids (C1-C10; C22- C25), 10 phloroglucinols (C11-C20) and 4 terpenoids (C21, C26-C28)] pure compounds. The chemical structures of the newly isolated compounds were elucidated on the basis of their 1D and 2D-NMR, HRMS, IR and UV spectroscopic data as heliteretifolin (C1), 1-benzoyl-3-(3-methyl- 2-butenylacetate)-phloroglucinol (helinivene A, C11), 1-benzoyl-3-(2-hydroxyl-3-methyl-3- butene-1-yl)-phloroglucinol (helinivene B, C12) and 8-(2-methyl-1-propanone)-3,5,7- trihydroxyl-2,2-dimethoxychromone (helinivene C, C13), while occurrence of 7- methoxyisoglabranin (C6), 4-methoxyquercetin (C8), 4`-methoxykaempferol (C9), mosloflavone (C10), 3β-24-dihydroxyterexer-14-ene (C21), 5,7,8-trihydroxy-3,6-dimethoxyflavone-8-O-2- methyl-2-butanoate (C22) and 15--hydroxy-(-)-kaur-16-en-19-oic acid (C28), from Helichrysum genus were reported for the first time. In vitro inhibition of oxidative stress by the isolated compounds were measured as total antioxidant capacity using the FRAP, TEAC, ORAC (hydroxyl and peroxyl radicals) as well as Fe2+-induced microsomal lipid peroxidation assays. Inhibitory activities against skin-diseases related enzymeswere evaluated in a tyrosinase and elastase non-biological system, while In vitro prooxidant behavior of the compounds was also investigated in the presence of copper (II). Compounds C7, C8, C11 and C12 in comparison with the commercial antioxidant EGCG demonstrated TEAC (4529.01 ± 2.44; 4170.66 ± 6.72; 19545.00 ± 10.25; 43615.73 ± 6.66; vs 11545.40 ± 17.28) μM TE/g respectively, and ORAChydroxyl radical (7.265 ± 0.71; 6.779 ± 3.40; 64.85± 10.95; 94.97 ± 5.80; vs 3.91 ± 4.65) X106 μM TE/g capacities, respectively. Inhibition of Fe2+- induced microsomal lipid peroxidation demonstrated by C7, C8, C11 and C12 expressed as IC50 values included: 2.931 ± 0.64; 6.449 ± 3.16; 5.115 ± 0.90; 3.553 ± 1.92 µg/mL respectively. Additionally, the total antioxidant capacities measured as FRAP (4816.31 ± 7.42; 3584.17 ± 0.54)µMAAE/g, and ORACperoxyl radical (17.836 ± 2.90; 12.545 ± 5.07) X 103 µMTE/g were also observed for compounds C7 & C8, respectively. Compound C7 demonstrated potent anti-tyrosinase activity with IC50 8.092 ± 7.14, while mild anti-tyrosinase activities were demonstrated by compounds C8, C11, C12, C22 and C23 and expressed as IC50 values (IC50 = 27.573 ± 3.11; 35.625 ± 4.67; 26.719 ± 5.05; 25.735 ± 9.62;24.062 ± 0.61) µg/mL respectively. Anti-elastase activity with IC50 values of 25.313 ± 7.85 µg/mL was observed for C13. This is the first scientific report to be carried out on the chemical and biological profiles of H. teretifolium.H. niveum and H. rutilans. The results suggest that these isolated compounds might become natural agents to inhibit oxidative stress and skin disease-related enzymes, with the prospect of being utilized in cosmetic products formulation upon further biological and clinicalinvestigations.
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Albati, Amal Abdulah. "PURIFICATION OF RECOMBINANT δ NP63 α AND CHARACTERIZATION OF PEPTIDE BINDING." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1447223071.
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Bennett, Raffeal A. "Characterization of the Solid-Electrolyte Interface on Sn Film Electrodes by Electrochemical Quartz Crystal Microbalance." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1399048324.
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Dong, Yanjing. "Identification, molecular cloning and functional characterization of novel bioactive peptides from amphibian skin secretion." Thesis, Queen's University Belfast, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.766285.
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Nasirpour, Maryam. "Synthesis and characterization of silver nanoparticles: a toxicity and metabolomics approach in skin cells." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15430.
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Mestrado em Ciência e engenharia de materiaisAs nanopartículas de prata (AgNPs) apresentam uma vasta gama de aplicações devido às suas inerentes propriedades físico-químicas e atividade biológica. Para além disso, a síntese verde de nanopartículas está a ser estudada como uma alternativa fiável e promissora para minimizar a utilização de substâncias prejudiciais utilizadas na síntese convencional. No presente trabalho, as AgNPs foram sintetizadas usando extratos de casca de Eucalyptus globulus e comparados com as sintetizadas por "Pulsed Laser Abalation in Liquids" (PLAL). Ambos os conjuntos de nanopartículas foram caracterizados por espectroscopia de UV-Visível, dispersão dinâmica de luz (DLS) e microscopia eletrónica de varrimento (SEM). A concentração de prata nas soluções aquosas de NPs foi avaliada por análise de Espectrometria de Emissão Ótica por Plasma Acoplado Indutivamente (ICP-OES). A toxicidade das partículas na linha celular de queratinócitos humanos, HaCaT, foi avaliada pelo ensaio convencional de MTT, para avaliação da viabilidade celular, e o ciclo celular foi analisado por citometria de fluxo. Finalmente, o perfil metabólico das células foi avaliado por espectroscopia de Ressonância Magnética Nuclear (NMR) e análise multivariada (metabolómica). Os resultados da caracterização mostraram que as AgNPs foram de facto formadas e apresentaram uma ampla distribuição de diâmetros de aproximadamente 30 a 70 nm no caso das nanopartículas produzida por síntese verde (GS) e de 10 nm com distribuição estreita para as sintetizadas via PLAL. As partículas dispersas em meio de cultura celular apresentaram ligeira aglomeração, enquanto o armazenamento à temperatura ambiente não induziu nenhum efeito no tamanho final. Contudo, o “envelhecimento” resultou na formação de uma pequena quantidade de nanoestruturas com formato de agulha. O MTT indicou um IC50 para as células HaCaT de aproximadamente 15 g/mL no caso das AgNPs preparadas por síntese verde e de 24 g/mL no caso das NPs sintetizadas via PLAL. As partículas de GS também induziram redução da proliferação na dose mais baixa e extensa morte celular na dose mais elevada, com a análise do ciclo celular mostrando paragem na fase G2. Os revestimentos quer das nanopartículas de GS, quer de PLAL não induziram toxicidade nas concentrações testadas, e a interferência de AgNPs com o ensaio de MTT foi considerada insignificante. A análise metabolómica revelou que as AgNPs em concentrações sub-tóxicas causaram alterações a nível do metabolismo energético, proteção antioxidante e membranas celulares.
Silver nanoparticles (AgNPs) present a wide range of applications due to their inherent physiochemical properties and biological activities. Moreover, green synthesis of metal nanoparticles is being studied as a reliable and promising alternative to minimize the use of harmful substances usually used in conventional synthesis. Here, AgNPs were synthesized using Eucalyptus globulus bark extract (GS) and compared against those synthesized externally via Pulsed Laser Abalation in Liquids (PLAL) technique. Both sets of particles were then characterized using UV-Visible spectroscopy, dynamic light scattering (DLS), and scanning transmission electron microscopy (SEM). The silver concentration of the aqueous solutions of NPs was also assessed by ICP-OES analysis. The toxicity of the particles on the human keratinocyte cell line, HaCaT, was evaluated using MTT, a conventional viability assay and cell cycle analysis was performed using flow cytometry. Finally, cellular metabolomics profiling was evaluated using NMR spectroscopy and multivariate analysis. Characterization results showed that AgNPs were indeed formed; presenting diameters of approximately 30 to 70 nm, and a wide size distribution for the GS route and 10 nm with a narrow distribution for the PLAL synthesis. Dispersion of particles in cell culture media promoted a slight agglomeration, while aging of particles at room temperature did not have an effect on their final size. Nevertheless, this aging time resulted in the formation of a small amount of needle-like nanostructures. MTT results indicated an IC50 value of approximately 15 ug/mL of silver for the GS route and approximately 24 ug/mL for the PLAL AgNPs. The GS particles also induced slower proliferation at the low concentration and extensive cell death at the high concentration, with cell cycle analysis showing arrest at the G2 phase. Neither the coating from the GS, nor the PLAL particles induced any toxicity at the concentrations tested, and the interference of AgNPs with the MTT assay was found to be negligible. Metabolomics using 1H NMR revealed that sub-toxic concentrations also caused significant alterations in energy metabolism, membrane modifications, and antioxidant protection in a dose and particle dependent manner. More specifically, GSH levels saw an increase, whereas amino acids, creatine compounds, and choline compounds all saw decreases. The GS AgNPs induced a stronger response in HaCaT cells than that of the PLAL.
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Nelson, Tiffany S. "Synthesis and Characterization of Crosslinked Polysiloxane-Clay Nanocomposites for Uses in Skin Care Products." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1154620091.
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Antecol, Michael Hal. "Biochemical and biological characterization of normal skin fibroblasts from individuals predisposed to dominantly inherited cancers." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74010.
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Yamakawa, Noriyuki. "A Clinical, Pathological and Genetic Characterization of Methotrexate-Associated Lymphoproliferative Disorders." Kyoto University, 2014. http://hdl.handle.net/2433/188632.
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Tessema, Efrem Nigussu [Verfasser]. "Delivery of phyto-ceramides into the stratum corneum of the skin using nanocarriers : structural characterization, formulation and skin permeation studies / Efrem Nigussu Tessema." Halle, 2018. http://d-nb.info/1155173171/34.
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Frykstrand, Ångström Sara. "Mesoporous magnesium carbonate : Synthesis, characterization and biocompatibility." Doctoral thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-281522.
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Mesoporous materials constitute a promising class of nanomaterials for a number of applications due to their tunable pore structure. The synthesis of most mesoporous materials involves a surfactant liquid crystal structure to form the pores. As well as the many advantages associated with this method of synthesis, there are disadvantages such as high production costs and a substantial environmental impact which limit the possibilities for large scale production. Therefore there is a need for other synthesis routes. The aim of the work described herein was to contribute to this field by developing a synthesis route that does not rely on surfactants for pore formation. A mesoporous magnesium carbonate material was therefore formed by self-assemblage of the particles around carbon dioxide gas bubbles, which functioned as pore templates. It was also possible to vary the pore diameter between 3 and 20 nm. The biocompatibility of the formed magnesium carbonate material was evaluated in terms of in vitro cytotoxicity and hemocompatibility, in vivo skin irritation and acute systemic toxicity. The results from the in vitro cytotoxicity, in vivo skin irritation and acute systemic toxicity test using a polar extraction vehicle showed that the material was non-toxic. While signs of toxicity were observed in the acute systemic toxicity test using a non-polar solvent, this was attributed to injection of particles rather than toxic leachables. In the in vitro hemocompatibility test, no hemolytic activity was found with material concentrations of up to 1 mg/ml. It was further shown that the material had anticoagulant properties and induced moderate activation of the complement system. The anticoagulant properties were ascribed to uptake of Ca2+. Finally, the ability of the material to increase the dissolution rate of the poorly soluble drug itraconazole was analyzed. Itraconazole was dissolved up to 23 times faster from the magnesium carbonate pores than when the free drug was used. The release rate from the delivery vehicle was dependent on the pore diameter. The work presented herein is expected to be useful for the development of alternative synthesis routes for mesoporous materials and also for encouraging the development of biomedical applications for these materials.
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Büttner, Claudia Christine [Verfasser]. "Shark skin inspired surfaces for aerodynamically optimized high temperature applications : fabrication, oxidation, characterization / Claudia Christine Büttner." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2011. http://d-nb.info/1014298024/34.
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Kim, Dong Sik [Verfasser], Ulrich [Akademischer Betreuer] Gösele, Wolf [Akademischer Betreuer] Widdra, and Carsten [Akademischer Betreuer] Ronning. "Growth and characterization of ZnO nanowires / Dong Sik Kim. Betreuer: Ulrich Gösele ; Wolf Widdra ; Carsten Ronning." Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2009. http://d-nb.info/1024873463/34.
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Schwartz, Anne. "Characterization of normal and androgen resistant-genital skin fibroblasts using high-resolution two-dimensional gel electrophoresis." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63378.
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Janbein, Malika [Verfasser]. "Characterization of the effects of Endophilin A3 on the physiological properties of SK3 channels / Malika Janbein." Ulm : Universität Ulm, 2016. http://d-nb.info/110483989X/34.
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De, Kwaadsteniet Michele. "Characterization of nisin F and its role in the control of respiratory tract and skin infections." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1285.
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Thesis (PhD (Microbiology))--University of Stellenbosch, 2009.Multidrug resistant strains of Staphylococcus aureus is presenting an increasing threat, especially immune compromised individuals. Many of these strains have developed resistance to newly approved drugs such as quinupristin-dalfopristin, linezolid and daptomycin. The search for alternative treatment, including bacteriocins (ribosomally synthesized antimicrobial peptides) of lactic acid bacteria is increasing . Lactococcus lactis subsp. lactis F10, isolated from freshwater catfish, produced a new nisin variant active against clinical strains of S. aureus. The operon encoding nisin F is located on a plasmid and the structural gene has been sequenced. The lantibiotic is closely related to nisin Z, except at position 30 where valine replaced isoleucine. The antimicrobial activity of nisin F against S. aureus was tested in the respiratory tract of Wistar rats. Non-immunosuppressed and immunosuppressed rats were intranasally infected with S. aureus K and then treated with either nisin F or sterile physiological saline. Nisin F protected immunosuppressed rats against S. aureus, as symptoms of an infection were only detected in the trachea and lungs of immunosuppressed rats treated with saline. The safety of intranasally administered nisin F was also evaluated and proved to have no adverse side effects. The potential of nisin F as an antimicrobial agent to treat subcutaneous skin infections was evaluated by infecting C57BL/6 mice with a bioluminescent strain of S. aureus (Xen 36). Immunosuppressed mice were treated with either nisin F or sterile physiological saline 24 h and 48 h after infection with subcutaneously injected S. aureus Xen 36. Histology and bioluminescence flux measurements revealed that nisin F was ineffective in the treatment of deep dermal staphylococcal infections. Non-infected and infected mice treated with nisin F had an influx of polymorphonuclear cells in the deep stroma of the skin tissue. This suggested that nisin F, when injected subcutaneously, may have modulated the immune system. Nisin F proved an effective antimicrobial agent against S. aureus-related infections in the respiratory tract, but not against subcutaneous infections. The outcome of nisin F treatment thus depends on the route of administration and site of infection.
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De, Kwaadsteniet Michèle. "Characterization of nisin F and its role in the control of respiratory tract and skin infections /." Link to the online version, 2009. http://hdl.handle.net/10019.1/1285.
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Moraes, Anderson de Souza. "Pharmaceutical characterization of thymol nanocapsules and evaluation of skin permeation and repellant activity against Aedes aegypti." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=17029.
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CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel SuperiorDengue is an infectious disease that may also happen in a severe form with hemorrhagic events. The etiological agent of the disease is an arbovirus wich is transmitted by the mosquito Aedes aegypti, the primary vector of the disease. The main actions to combat the disease are mosquito control and personal protection that can take place using repellents. Almost all repellents have DEET as active substance, which has use restrictions. In this context, thymol (monoterpene) has become a potential insect repellent against Ae. aegypti, and the use of technologies is essential to the viability of a repellent thymol based product. Given the above, the aim of this study was the preparation and pharmaceutical characterization of thymol nanocapsules and evaluation of skin permeation, in vitro cytotoxicity and mosquito repellence (Ae. aegypti). For this purpose, we developed and validated analytical method for identification and quantification of thymol by HPLC-PDA. Nanocapsules thymol (NCT - 1%) showed an active content of 85%. Continuing the characterization, NCT were analyzed for the mean diameter (D), polydispersity index (PDI), potential zeta (PZ), encapsulation efficiency, pH and product stability . Results shared showed an average diameter of approximately 150 nm, negative PZ (-27,83 Â 2,60), PDI less than 0.2 and an encapsulation efficiency of 98%. NCT and ethanolic solution of thymol were evaluated for release, permeation and retention of thymol through dialysis membrane or the porcine ear skin in a Franz diffusion cell model. NCT showed release control of thymol in relation to the ethanolic solution of thymol, which showed a maximal release of 53.8% of the dose within 24 hours of testing, higher than the amount released by the NCT (17.6%) indicating the decrease in permeability when nanoencapsulated. Cytotoxicity analysis of free and encapsulated thymol (50 to 100 ug / ml) in human keratinocytes by MTT assay showed cytotoxicity of free thymol - 100 ug / mL (% viable cells: 16.1 Â 3.2 ), which was virtually devoid with this encapsulation (% viable cells: 92.7 Â 31). Preliminary assessment of the repellent potential of NCT against Ae. aegypti showed that in human topical administration of the product promoted up to 67% repellency. The results suggest that standardized NCT has morphological and chemical characteristics of interest to a nanossystem, plus the potential repellent against Ae. aegypti mosquito.
A dengue à uma doenÃa infecciosa que pode se manifestar de forma grave, com quadros hemorrÃgicos. O agente etiolÃgico à um arbovirus transmitido pela picada do mosquito Aedes aegypti, principal vetor da doenÃa. As principais medidas de combate sÃo controle do mosquito e proteÃÃo individual, que pode dar-se com o uso de repelentes. Quase a totalidade dos repelentes no mercado possui DEET como ativo, que possui restriÃÃes de uso. Neste sentido, o timol (monoterpeno) tem-se mostrado promissor como repelente de inseto (Ae. aegypti), sendo a agregaÃÃo de tecnologias essencial para a viabilidade de um produto repelente à base de timol. Diante do exposto, o objetivo do presente trabalho foi a preparaÃÃo e caracterizaÃÃo farmacÃutica de nanocÃpsulas de timol, com avaliaÃÃo da permeaÃÃo cutÃnea, citotoxicidade e atividade repelente de inseto (Ae. aegypti). Para tanto, foi desenvolvido e validado mÃtodo analÃtico para identificaÃÃo e quantificaÃÃo do timol por CLAE-DAD nas nanocÃpsulas de timol (NCT â 1%), que apresentou um teor de ativo em torno de 85%. Prosseguindo a caracterizaÃÃo das NCT, foram determinados o diÃmetro mÃdio, Ãndice de polidispersÃo (PDI), potencial zeta (PZ), eficiÃncia de encapsulaÃÃo e pH, alÃm do estudo de estabilidade. AnÃlises das NCT mostraram um diÃmetro mÃdio de aproximadamente 150 nm, PZ negativo (-27,83  2,60), PDI abaixo de 0,2 e uma eficiÃncia de encapsulaÃÃo de 98 %. NCT e soluÃÃo etanÃlica de timol foram avaliadas quanto à liberaÃÃo, permeaÃÃo e retenÃÃo de timol atravÃs de membrana de diÃlise ou da pele de orelha suÃna, em um modelo de cÃlulas de difusÃo de Franz. A NCT mostrou controle da liberaÃÃo de timol em relaÃÃo à soluÃÃo etanÃlica de timol, que apresentou por sua vez uma liberaÃÃo mÃxima de 53,8% da dose em 24 horas de ensaio, superior à quantidade liberada pela NCT (17,6%), evidenciando a diminuiÃÃo da permeabilidade do timol quando nanoencapsulado. AnÃlise da citotoxicidade do timol livre e encapsulado (50 e 100 g/mL) em queratinÃcitos humano atravÃs do teste de MTT, mostrou a citotoxicidade do timol livre - 100 g/mL (% cÃlulas viÃveis: 16,1  3,2), que foi praticamente destituÃda com a encapsulaÃÃo deste (% cÃlulas viÃveis: 92,7  31). AvaliaÃÃo preliminar do potencial repelente das NCT ao mosquito Ae. aegypti em humano mostrou que a administraÃÃo tÃpica desse produto promoveu atà 67 % de repelÃncia. Os resultados obtidos sugerem que as NCT padronizadas possuem caracterÃsticas morfolÃgicas e quÃmicas de interesse para um nanossistema, alÃm do potencial repelente ao mosquito Ae. aegypti.
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Rosa, Ramon Gabriel Teixeira. "Assembly, characterization, and validation of a fluorescence lifetime rigid endoscope for clinical imaging of skin lesions." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-04062018-104844/.
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Fluorescence based microscopy techniques have been extensively used in biological sciences. The most common approach is the steady-state fluorescence microscopy. Although the said approach is powerful, it often lacks sensitivity to detect several biochemical processes that may indicate relevant conditions of biological tissues. The fluorescence dynamics analysis not only brings intrinsic information about the tissue, but is also less sensitive to the medium scattering and absorption, and sometimes capable of distinguishing between fluorescent structures with indistinguishable spectra. The intrinsic fluorescence lifetime of biological tissues is usually affected by some clinical conditions, especially when those conditions cause or are correlated with metabolic modifications. Time-resolved spectroscopy techniques can be used to detect those modifications and may be used as a tool to improve the detection and diagnosis rate of such conditions. Fluorescence Lifetime Imaging Microscopy (FLIM) combines the temporal resolution and the microscopy concept, so fluorescence lifetime images can be generated. This technique has a great potential for clinical applications since it may be able to detected lesions and delineate its borders. However, FLIM usually demands a more sophisticated instrumentation than most techniques based on the steady-state approach, what creates a difficulty for moving such a system to a clinical setting. We report the assembly, characterization, validation, and clinical application of a multispectral FLIM system featuring a handheld probe composed of a laser scanning rigid endoscope. The assembled system uses a 355 nm short pulsed laser as excitation and has three spectral channels, targeting the emission of collagen, NADH, and FAD, which are important endogenous fluorophores. The system acquires images of 8.65 x 8.65 mm2 areas in ~ 2.4 s. MATLAB codes were written to process the images using a biexponential model and a modified phasor approach. In vivo validation measurements of tumors induced in mice were performed. The system was also validated with in vivo imaging of skin of healthy volunteers. The assembled FLIM system was moved to Hospital Amaral Carvalho, where we performed a pilot clinical study, in which different types of skin lesions were imaged in vivo in a clinical setting. A significant contrast was achieved on seborrheic keratosis, Bowen´s disease, and sclerodermiform basal cell carcinoma tumors. These results indicate the potential of this technique for clinical imaging of skin lesions.Técnicas de microscopia baseadas em fluorescência têm sido extensamente utilizadas em ciências biológicas. A abordagem mais comum se baseia na microscopia de fluorescência de estado estacionário. Apesar de poderosa, essa abordagem frequentemente não apresenta sensibilidade suficiente para detectar diversos processos bioquímicos que podem ser indicadores de relevantes problemas em tecidos biológicos. A análise da dinâmica da fluorescência não apenas trás informações intrínsecas sobre o tecido, mas também é menos sensível a espalhamento e absorção pelo meio, além de ser capaz de distinguir entre estruturas fluorescentes com espectros indistinguíveis em alguns casos. O tempo de vida intrínseco de tecidos biológicos é normalmente afetado por condições clínicas, especialmente quando estas condições causam ou são relacionadas a modificações metabólicas. As técnicas de espectroscopia resolvidas no tempo podem detectar essas modificações e podem ser utilizadas como uma ferramenta para melhorar a detecção e o diagnóstico dessas condições. A Microscopia de Tempo de Vida de Fluorescência (FLIM) combina a resolução temporal ao conceito de microscopia, de forma que imagens de tempos de vida de fluorescência podem ser gerados. Essa técnica tem um grande potencial para aplicações clínicas uma vez que ela pode ser capaz de detectar lesões e delinear suas bordas. No entanto, FLIM requer uma instrumentação muito mais sofisticada do que a maior parte das técnicas baseadas no estado estacionário, o que cria uma dificuldade para que tais sistemas possam ser levados a ambientes clínicos. Nós reportamos a montagem, caracterização, validação e aplicação clínica de um sistema FLIM multiespectral com uma sonda manual composta de um endoscópio rígido de varredura laser. O sistema montado utiliza um laser pulsado de 355 nm como fonte de excitação e conta com três canais espectrais, visando a emissão do colágeno, do NADH e do FAD, três importantes fluoróforos endógenos. O sistema é capaz de adquirir imagens de áreas de 8,65 x 8,65 mm2 em ~ 2,4 s. Códigos em MATLAB foram escritos para processar as imagens usando um modelo biexponencial e uma abordagem modificada dos fasores. Medidas in vivo de tumores induzidos em camundongos foram realizadas para validação do sistema. O sistema também foi validado com a realização de medidas in vivo da pele de voluntários sadios. O sistema montado foi levado ao Hospital Amaral Carvalho, onde realizamos um teste clínico piloto no qual diferentes tipos de lesões de pele foram imageados in vivo em um ambiente clínico. Um contraste significante foi alcançado em tumores de queratose seborreica, doença de Bowen e carcinoma basocelular esclerodermiforme. Esses resultados indicam o potencial desta técnica para o imageamento clínico de lesões de pele.
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Jhanwar, Ankur. "Isolation and Characterization of Different Aggregates of Lipid from Bovine Milk." DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/231.
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Bovine milk fat globules naturally vary from less than 0.2 µm to 15 µm in diameter. Milk has at least two distinct distributions of fat globules. While the majority (~90%) of globules in milk are of the smaller distribution (average diameter of 0.4 µm), virtually all the fat is carried in the larger globules (average diameter 3.5 µm). This distribution suggests some compositional and/or functional significance might exist between the two populations of fat globules, which may be related to origin of these globules in the lactating cell.
Milk fat globules have a unique structure, composed of a core droplet of non polar lipids (triacylglycerol) surrounded by a lipid bilayer membrane known as milk fat globule membrane (MFGM). Other than MFGM, there is another source of membrane that has been identified in skim milk. It has been hypothesized that this skim milk membrane (SMM) is derived from MFGM, but little data are available to support this idea, and the membrane may also have alternate origins.
In this study, different aggregates of lipids (small and large fat globules, SMM, skim milk) from milk were isolated and characterized for their lipid contents. Isolation of small and large fat globules fractions was verified by laser diffraction particle size analysis. The lipids were extracted from isolated different lipid aggregates and individual classes were separated using thin layer chromatography. Lipids were transesterified to fatty acid methyl esters and analyzed by gas chromatography-mass spectrometry.
The results indicate that there are some compositional differences between native milk fat globule membranes of different sizes. For example, the total phospholipid fraction of small fat globules (SFG) contained significantly more unsaturated C18:1n9 and C18:2n6 than large fat globules (LFG). Conversely, sphingomyelin composition of SFG contained less C18:1n9 and C18:2n6cc, but more long chain fatty acids C22:0, C23:0, and C24:0. Phosphatidylethanolamine composition of SMM contained more C17:1 than SFG and LFG. The composition of C18:1n9 in triacylglycerol increased with fat globule size. Clear differences were also found in lipid profile of SMM and small and large fat globules from milk. Composition differences between SMM and native milk fat globules of different sizes suggest that origin of this membrane material in skim milk might have some different source than that of MFGM.