Dissertations / Theses on the topic 'Anoxemia'
To see the other types of publications on this topic, follow the link: Anoxemia.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Anoxemia.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Kim, Song-Jung. "Hypoxemia Attenuates Coronary Autoregulation." Thesis, University of North Texas, 1989. https://digital.library.unt.edu/ark:/67531/metadc500734/.
Full textAbstract:
The effect of hypoxemia on coronary autoregulation was investigated in nine anesthetized, open-chest dogs. The anterior descending coronary artery (LAD) was cannulated and perfused with normoxic arterial blood and with moderately hypoxic blood (0₂ content = 10 + 1 ml 0₂ /dl). LAD blood flow was measured as perfusion pressure was varied from 140 to 40 mmHg. At perfusion pressures at and above 40 mmHg, hypoxemia significantly increased LAD flow. During normoxia, the autoregulatory closed-loop gain (Gc) was significantly greater than zero at perfusion pressures from 60 to 120 mmHg. During hypoxemia, Gc was greater than zero only at perfusion pressures from 80 to 100 mmHg. During hypoxemia, LAD blood flow increased sufficiently to maintain oxygen delivery and consumption constant, but the range and potency of autoregulation was attenuated.
2
Vedam, Hima. "Short-term hypoxia and arterial stiffness." Thesis, The University of Sydney, 2007. https://hdl.handle.net/2123/28093.
Full textAbstract:
The studies in this thesis assess the ventilatory and vascular effects of short-term awake isocapnic hypoxia in healthy subjects and those with obstructive sleep apnoea (OSA). The particular focus of this thesis is the impact of the hypoxic stimulus on indices of arterial stiffness, in particular the augmentation index (AIx) and time to reflection (Tr). The role of nitric oxide in this response in healthy subjects is also examined.
3
Saul, Lloyd. "The effect of repeat exercise on exercise-induced arterial hypoxemia /." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98792.
Full textAbstract:
Exercise-induced hypoxemia [EIAH, arterial PO2 < 90 mmHg and/or alveolar-arterial oxygen partial pressure gradient (A-a DO2) ≥ 25 mmHg] occurs during strenuous exercise in some healthy women. There is conflicting opinion if performing successive bouts of strenuous exercise reduces the severity of EIAH. The aim was to (a) test the hypothesis that the severity of EIAH would be reduced with three successive bouts of strenuous exercise, (b) to determine if repeated bouts of exercise increases hyperventilation thus improving arterial PO2. Seven fit female subjects with EIAH [arterial PO2 or PaO2= 88 +/- 2 mmHg, A-a DO 2 = 25 +/- 3 mmHg and 7 fit female control subjects (PaO2 = 100 +/- 5 mmHg, A-a DO2 = 16 +/- 5 mmHg) performed three bouts of intense exercise on a cycle ergometer at 236 +/- 27 watts [oxygen consumption at end of each set = 48 +/- 6 mL/kg/min, or 96 +/- 5% of maximum] for 5 min each with 10 min of rest between sets. Arterial PO 2 increased [EIAH Delta = +4 +/- 5 mmHg. 95% CI = 0.6 to 7.8; Control Delta = +2 +/- 2 mmHg. 95% CI = 0.4 to 3.6] and arterial PCO 2 or PaCO2 decreased [EIAH Delta = -5 +/- 4 mm Hg, 95% CI = -7.4 to -2.2; Control Delta = -4 +/- 2 mmHg, 95% CI = -5.8 to -2.4] between set 1 and set 3 (P< 0.05). Also, 34% of the variance in the change in PaO2, was explained by the variance in the change of PaCO2 (P < 0.05). In conclusion, repeat exercise improves PaO2, which is related to improved hyperventilation.
4
Li, Jingping, and 李京平. "Role of tissue hypoxia in periodontitis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47849563.
Full textAbstract:
In periodontitis, local oxygen supply and consumption in gingival tissues may be
significantly altered due to the inflammatory process. The etiology agent of
periodontal disease i.e. anaerobic bacterial biofilm is known to confer a low
oxygen tension in the vicinity of periodontitis lesion. The oxygen shortage will
lead to the stabilization of HIF-1α, the regulatory subunit of hypoxia-inducible
factor (HIF)-1, which through controlling specific downstream genes transcription
may modulate multiple cellular functions and hence shape the process of
periodontitis. Lipopolysaccharide (LPS), a cell wall component of anaerobic
bacteria, has been considered to be involved in the pathogenesis of periodontitis. Its
interaction with host peptides including LPS-binding protein (LBP), CD14, MD-2
and Toll-like receptor (TLR) 4 may trigger the production of inflammatory
cytokines.
In this project we hypothesize that hypoxia and bacterial components may induce
HIF-1α activity, which in turn impacts upon on the pathological process of
periodontitis. This project aimed to detect in vivo expression of HIF-1α and TLR4
in human gingivae; to examine whether LPS could induce HIF-1α activity through
pattern recognition receptor like TLR4 on human primary gingival fibroblasts
(HGF); and to investigate the combined effect of hypoxia and LPS on type I
collagen metabolism in HGF.
Human gingival biopsies were collected from advanced periodontitis or clinically
healthy sites. By immunohistochemistry, both HIF-1α and TLR4 peptides
appeared to express in gingival epithelium. In periodontal pockets, there appeared
a marked increase in HIF-1α and TLR4 expression in fibroblast-like and
leukocyte-like cells.
Human primary gingival keratinocytes (HGK) and fibroblasts (HGF) were
cultured. Transcripts of TLR4, MD-2 and CD14 were identified in HGK, HGF
and periodontal tissue using RT-PCR. Their protein products were identified in
both cell types in vitro using immunoblotting. LBP transcript was only found in
gingival biopsies but not in HGK and HGF culture.
HGF treated by Escherichia coli LPS ranging from 0.2 μg/mL to 200 μg/mL
showed nuclear accumulation of HIF-1α peptide, detectable by
immunocytofluorescence and immunoblotting. This accumulation could be
attenuated by treatment with TLR4-neutralizing antibody. Under hypoxia, LPS
further increased HIF-1α accumulation. Using quantitative real-time PCR (qPCR),
hypoxia and/or LPS appeared to enhance the transcription of certain enzymes or
enzyme subunits that are related to collagen assembly and crosslink, including
prolyl 4-hydroxylases, lysyl hydroxylases, lysyl oxidase and lysyl oxidase-like
enzymes. These increased transcription could be downregulated by pretreatment
with TLR4-neutralizing antibody or an HIF-α inhibitor,
3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1).
Finally, preliminary experiments showed KN-93 [Ca2+/Calmodulin-dependent
protein kinase (CaMK) II inhibitor] or cyclosporine-A (calcineurin inhibitor)
appeared able to attenuate the LPS-induced HIF-1α accumulation, indicating a
possible role for intracellular calcium signal in regulating HIF-1α.
In conclusions, human periodontitis is associated with increased expression of
TLR4 and HIF-1α in gingivae; hypoxia causes and LPS/TLR4 signal associate
with HIF-1α accumulation and activity in human gingival fibroblasts, and
subsequently modulate in a certain extend collagen metabolism through
upregulating the transcript expression of several collagen-related proteins. All
these implicate possibility of an adaptive physiological or pathological response
of human gingival fibroblasts towards gram-negative bacterial biofilm challenge
in human periodontium.published_or_final_version
Dentistry
Doctoral
Doctor of Philosophy
5
Tam, Wai-kit, and 譚偉傑. "Role of hypoxia inducible factor-alpha (HIF-α) genes inchondrogenesis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B47849770.
Full textAbstract:
Cartilage is an essential skeletal connective tissue in vertebrates. It comprises
extracellular matrix components, especially for collagens and proteoglycans. Once
the cartilage is damaged, it has limited self-repair capacity. Thus, by
understanding the dynamic cellular process of chondrogenesis and chondrocyte
differentiation would be necessary in developing therapeutic approaches for
cartilage repair. Currently, there is a great interest in the development of cell
therapy to repair damaged tissues. In particularly, human mesenchymal stem cells
(hMSCs) are attractive candidates for the treatment of skeletal system disorders
because they can be greatly expanded ex vivo and they readily differentiate into
chondrocytes upon stimulation. Studies have demonstrated low environmental
oxygen tension could affect the chondrogenic differentiation of hMSCs. The three
basic helix-loop-helix (bHLH) motif-containing hypoxia inducible factor α (HIF-α)
subunits (i.e. HIF-1α, HIF-2α and HIF-3α) are the major oxygen-sensitive
transcription factors regulating physiological responses under hypoxia. Of
significance, HIF-1α has been reported to induce a hyaline chondrocyte-like
phenotype in human articular chondrocytes. The aim of this study was to
investigate the roles of all three human HIF-α paralogues in chondrogenesis,
particularly for the transcriptional regulation of chondrocyte-specific genes,
including type II collagen (COL2A1) and aggrecan (AGC1). The effect of all three
human HIF-α paralogues on the chondrogenic differentiation of hMSCs could
then be investigated. Self-inactivating lentivirus vector (SIN-LV) shuttle plasmids
coding for murine SOX9, wild-type and oxygen-insensitive versions of human
HIF-1α and HIF-2α or wild-type HIF-3α were generated. These plasmids were
used in luciferase-based promoter assays and to generate SIN-LV particles for
overexpression studies. Our data revealed that SOX9, a key transactivator of
chondrogenesis, strongly activates the transcription of COL2A1 and AGC1.
Ectopic expression of HIF-2α could also induce the transcription of COL2A1 and
AGC1. Strikingly, a cooperative transcriptional up-regulation of COL2A1 and
AGC1 via the overexpression of HIF-1α and SOX9 was observed. Furthermore,
HIF-3α was shown to inhibit the SOX9–dependent transcriptional up-regulation
of COL2A1 and AGC1. Here, the multipotency of hMSCs cultured under
hypoxia (1% O2 tension) was also illustrated. A pilot study for overexpressing
exogenous gene in chondrogenic stimulated hMSC pellets via SIN-LV particles is
described. Eventually, a rationale is provided for manipulating HIF-α expression
in chondrogenic stimulated hMSC pellet via SIN-LVs encoding HIF-α subunits to
study the contribution of HIF-α paralogues on promoting the chondrogenic
differentiation of hMSCs.published_or_final_version
Orthopaedics and Traumatology
Doctoral
Doctor of Philosophy
6
Dinkelacker, Stephen A. "Ecological physiology of overwintering in hatchling Blanding's turtles (Emydoidea blandingii) insights into anoxia tolerance and freeze tolerance /." Oxford, Ohio : Miami University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1091035075.
Full text
7
Ma, Shufen. "Seasonal anoxia in the Delaware Inland Bays its development and its effects on nutrient and algal community structure /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 172 Mb., 1.33 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3200545.
Full text
8
Schwab, David Earl. "Electron paramagnetic resonance investigations of adducts of human hemoglobin." Thesis, Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/schwab/SchwabD0510.pdf.
Full textAbstract:
Hemoglobin transports oxygen to the tissues of the body. The delivery of oxygen to tissues by hemoglobin is dependent on blood flow, which is determined by vessel tension regulated by local oxygen gradients. Dilation of the blood vessels in the microcirculation of tissues under high metabolic demand is induced by the endothelium-derived relaxation factor, nitric oxide, in a process known as hypoxic vasodilation. Although the means of nitric oxide bioactivity preservation and transportation in the blood are disputed, it is clear that S-nitrosohemoglobin, a nitrosylated variant of hemoglobin, plays a pivotal role. The details surrounding S-nitrosohemoglobin formation in vivo, however, remain uncertain. Using electron paramagnetic resonance (EPR) spectroscopy, in conjunction with detailed spectral simulation and least-squares fitting, various hemoglobin species which possibly participate in the formation of S-nitrosohemoglobin were characterized. The EPR spectrum of methemoglobin-nitrite, a purported precursor to S-nitrosohemoglobin formation, was determined to be a composite spectrum arising from the presence of two species, the origin of which is proposed to lie in the differences between the distal heme pockets and histidine residues of the alpha- and beta-subunits of hemoglobin. By direct measurement of methemoglobin-nitrite by EPR spectroscopy, the weak affinity of methemoglobin for nitrite was confirmed, precluding nitrite-methemoglobin from having a direct role in physiological hypoxic vasodilation. Furthermore, the temperature dependence of the EPR spectra of the various species of neat methemoglobin was determined, as was the temperature dependence of the nitrosyl-hemoglobin (Hb(NO)â‚„) spectrum at high frequency. The high frequency spectrum of Hb(NO)â‚„ provided additional resolution of the axial and rhombic components of the spectrum, but revealed no evidence of distinct subunit spectra. Finally, synthetic routes to generate Fe(II)NO/Fe(III)-Hb hybrids have been presented, which, among other things, demonstrated that bolus addition of nitric oxide can produce similar results as the addition of time and condition dependent nitric oxide donors. Overall, this work expands the understanding of hemoglobin, specifically with regard to hemoglobin species with possible involvement in S-nitrosohemoglobin formation.
9
Mc, Govern Naomi Nuala. "The effects of hypoxia on neutrophil biology." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609111.
Full text
10
Woodside, John. "Redox regulation of vascular NO bioavailability during hypoxia : implications for oxygen transport and exercise performance." Thesis, University of South Wales, 2010. https://pure.southwales.ac.uk/en/studentthesis/redox-regulation-of-vascular-no-bioavailability-during-hypoxia(9f798152-e88b-408d-85bc-b6dda49a7e6b).html.
Full textAbstract:
The reduction in O2peak at altitude is well documented. Maximal exercise in hypoxia is accelerated through a reduction in O2 supply with contributions from central and peripheral origins of fatigue. Changes in cerebral and muscle oxygenation have not been well characterised during incremental exercise in hypoxia. It is possible attainment of O2peak is driven by the oxygenation profile of these tissues whilst changes in molecular biomarkers of endothelial function could provide some insight into the mechanisms driving systemic and regional O2 delivery and vascular hypoxic sensing capabilities. The first study of this thesis examined the impact of acute hypoxia (FIO2 = 0.12) on the cerebral and muscle oxygenation response to incremental cycling exercise using NIRS (n = 14; age: 23 ± 5yr; height: 1.80 ± 0.07m; weight: 84 ± 8kg). The profiles were characterised at equivalent relative and absolute exercise intensities and molecular blood-borne markers of O2 sensing and function were measured before and immediately after maximal exercise for changes in oxidative stress (A• and 3-NT), NO metabolites (NOx, NO3•, NO2• and RSNO) and cell adhesion molecules (sICAM-1 and sVCAM-1). The key observations from this study were: 1) O2peak decreased by 22% and the magnitude of cerebral and muscle deoxygenation (↓O2Hb and ↑HHb) was greater in hypoxia, 2) the slope for the relative HHb response was similar between conditions whereas there was an accelerated slope across the absolute workloads in hypoxia implying cycling performance was driven by a premature attainment of maximal O2 extraction capacity of the muscle, 3) there was no evidence suggesting cerebral O2 metabolism was impaired in hypoxia however since SaO2 was 78 ± 4% at PPO it is possible the reduction in systemic O2 delivery could have influenced central fatigue, 4) there was a tendency for a rightward shift in the cerebral THb profile in hypoxia and although muscle THb peaked at 80% PPO in both trials, the response also tended to be lower in hypoxia, 5) there was no change in oxidative stress markers and NOx after exercise, 6) RSNO increased and NO2• decreased after maximal exercise. The decline in NO2• was attenuated in hypoxia possibly due to a blunted NO2•-HHb-NO pathway and may explain the systemic hypoperfusion response, 7) The increase in sICAM-1 and sVCAM-1 after exercise was augmented in normoxia, 8) Only when normoxia and hypoxia data was pooled was there a correlation between sVCAM-1 pre-post exercise and O2peak. Intermittent hypoxia (IH) may be used to improve the efficiency of exercise training and as a pre-acclimatisation strategy prior to high altitude ascent. The purpose of the second study was to evaluate the efficacy of a 10 day IH regime consisting of 9x 5 min daily exposures of 9.5% O2 breathing followed by equal periods of normoxia on submaximal and maximal cardiorespiratory responses to exercise in hypoxia. Additionally, cerebral and muscle oxygenation was monitored throughout incremental cycling to exhaustion and changes in NO metabolites (NO3•, NO2• and RSNO) and CAMs (sICAM-1 and sVCAM-1) were measured before and immediately after maximal exercise. The key observations from this study were: 1) a tendency for IH to reduce submaximal O2 and increase O2peak in hypoxia, 2) IH increased the muscle THb response to exercise due an increased intercept for both the muscle O2Hb and HHb in the absence of any change in slope, 4) cerebral oxygenation increased (↑O2Hb) at rest and during exercise, 4) the reduction in nitrite was attenuated in the IH group whilst resting sICAM-1 decreased and the pre-post maximal exercise increase in sICAM-1 was augmented after IH. It is concluded that exercise performance in acute hypoxia is driven by the magnitude of hypoxaemia and an accelerated rate of cerebral and muscle deoxygenation. Molecular biomarkers of endothelial function in particular, NO2• and CAMs, are also influenced by hypoxia and may contribute to the reduction in O2peak. IH may be used to improve exercise economy and O2peak in hypoxia by improving cerebral and muscle oxygenation in the absence of any change in central O2 delivery. It is possible a recalibration of mechanisms that affect NO bioactivation could have enhanced vascular hypoxic sensitivity, O2 delivery and adaptation within brain and muscle tissue which ultimately translated to an improved hypoxic exercise performance. These results give motivation for athletes and mountaineers to incorporate an IH strategy prior to athletic performance at altitude.
11
Mendenhall, Alexander R. Padilla Pamela Ann Fox. "Genetic mechanisms for anoxia survival in C. elegans." [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-9062.
Full text
12
White, Carine Petris Michael J. "Inflammation and hypoxia novel regulators of mammalian copper homeostasis in macrophages /." Diss., Columbia, Mo. : University of Missouri--Columbia, 2008. http://hdl.handle.net/10355/6624.
Full textAbstract:
Title from PDF of title page (University of Missouri--Columbia, viewed on March 8, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Michael J. Petris. Vita. Includes bibliographical references.
13
Ward, Julie A. "Clinical relevance of hyperlipidaemia or hypoxaemia to intramyocellular lipid content." Thesis, The University of Sydney, 2005. https://hdl.handle.net/2123/28044.
Full textAbstract:
Intramyocellular lipid (IMCL), the spherical droplets of triglyceride stored within human skeletal muscle cells, is elevated in insulin resistant states such as type 1 and type 2 diabetes, obesity and congenital or acquired lipodystrophy, Among healthy sedentary individuals, there is a significant association between IMCL content and whole body insulin sensitivity: the lower the insulin sensitivity, the greater the IMCL content. This relationship is independent of other important factors such as the degree of adiposity and fasting plasma concentrations of triglycerides and non—esterified fatty acids (NEFA). The underlying mechanisms, although not yet fully understood, are thought to involve dysregulated metabolism of skeletal muscle lipid that may interfere with normal glucose metabolism. Whether IMCL is directly involved in the process of insulin resistance or subject to impaired metabolism under conditions of insulin resistance is not known. IMCL content has also been associated with other metabolic variables. Fasting plasma NEFA concentrations correlate positively with IMCL levels in several sub-populations. Abdominal visceral fat content has been positively associated with IMCL content, suggesting that IMCL accumulation is partly due to the uptake of free fatty acids released from excess visceral fat. IMCL content is also associated with reduced supply of oxygen to skeletal muscle, suggesting that myocellular triglyceride may accumulate when there are subtle decreases in oxygenation of the muscle microvasculature. The aim of this research was to examine these relationships in the context of specific clinical conditions characterised by hyperlipidaemia or hypoxaemia to determine the impact of these abnormalities on IMCL content. It was hypothesised that: - IMCL accumulation is influenced by cholesterol-induced vascular abnormalities that compromise skeletal muscle fat oxidation via reduced muscle oxygen supply;
- IMCL content in the context of a disorder of cholesterol metabolism is still influenced by factors such as insulin sensitivity, circulating NEFA levels and visceral adiposity; - IMCL accumulation is partly attributable to the degree of hypoxaemia in the muscle microvasculature that might favour fat storage over fat oxidation; and - IMCL content in the soleus muscle would decrease after elimination of hypoxaemia in sleep-disordered breathing. To address these hypotheses, studies were undertaken using the non-invasive technique of proton magnetic resonance spectroscopy (lH-MRS) for measurement of soleus IMCL content. Subjects included adults and children with familial hypercholesterolaemia (FH - a model of hyperlipidaemia) and men with moderate to severe obstructive sleep apnoea (OSA - a model of hypoxaemia).
14
Lapaz, Allan de Marcos. "Comportamento fisio-bioquímico da soja em resposta ao encharcamento do solo associado ao excesso de ferro /." Ilha Solteira, 2019. http://hdl.handle.net/11449/191438.
Full textAbstract:
Orientador: Ana Carolina FirminoResumo: O encharcamento do solo é um problema comum em algumas áreas agricultáveis, inclusive em regiões sob cultivo de soja (Glycine max). Em solos encharcados, ocorre a depleção de O2 do solo pelos microrganismos aeróbicos e plantas, afetando os processos metabólicos e fisiológicos das plantas após sofrerem anoxia no tecido radicular. Outro fator prejudicial neste contexto, é o aumento exponencial da disponibilidade de ferro (Fe) no solo, o que pode resultar na absorção excessiva do Fe pelas plantas. No primeiro experimento, o objetivo foi avaliar a vulnerabilidade do aparato fotossintético e produção de biomassa de duas cultivares de soja no estágio fenológico V2, sob condição hídrica adequada e diferentes níveis de encharcamento do solo associada a uma concentração moderada e duas concentrações tóxicas de Fe. No segundo experimento, o objetivo foi avaliar o comportamento fisiológico e bioquímico da soja cultivar Agroeste 3680 associado ao desenvolvimento das vagens (estágio fenológico R3) sob solo não encharcado e encharcado combinado com uma concentração moderada e duas concentrações tóxicas de Fe. No primeiro experimento, o aparato fotossintético das cultivares de soja responderam diferentemente ao encharcamento e à disponibilidade de Fe no solo. Ambas cultivares foram vulneráveis ao encharcamento de 100% em todas as concentrações Fe, o que resultou em danos acentuados às trocas gasosas, concentração de clorofilas e, consequentemente, levou à diminuição da biomassa seca da part... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Soil waterlogging is a common problem in some agricultural areas, including regions under soybean (Glycine max) cultivation. In waterlogged soils, soil O2 depletion occurs due to aerobic microorganisms and plants, affecting the metabolic and physiological processes of plants after suffering anoxia in their root tissue. Another harmful factor of this situation is the exponential increase in the availability of iron (Fe) in the soil, which may result in excessive Fe uptake by plants. In the first experiment, the objective was to evaluate the vulnerability of the photosynthetic apparatus and biomass production of two soybean cultivars at the phenological stage V2, under optimal water condition and different levels of soil waterlogging, combined with one moderate and two toxic levels of Fe. While in the second experiment, the objective was to evaluate the physiological and biochemical behaviour of soybean cultivar Agroeste 3680, associated with the development of pods (at the phenological stage R3) in non-waterlogged and waterlogged soil, combined with one moderate and two toxic levels of Fe. In the first experiment, the photosynthetic apparatus of the two soybean cultivars responded differently to waterlogging and the availability of Fe in the soil. Both cultivars were vulnerable to waterlogging of 100% at all concentrations Fe, which resulted in damage to gas exchange and chlorophyll levels, and consequently, led to lower shoot and root biomass accumulation. The photosynthetic ... (Complete abstract click electronic access below)
Mestre
15
Fogelson, Susan B. "Effects of anoxia of histology, bacteriology, condition index, glycogen levels, and fecundity in the Eastern oyster Crassostrea virginica." Auburn, Ala, 2007. http://repo.lib.auburn.edu/2007%20Spring%20Theses/fogelson_susan_26.pdf.
Full text
16
Rice, Anthony John. "Mechanisms of exercise-induced hypoxemia in trained endurance athletes /." Title page, contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phr4951.pdf.
Full text
17
Hung, Ming-wai. "Protective effects of melatonin on hippocampal and vascular injuries induced by chronic and intermittent hypoxia in rats." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B39793941.
Full text
18
Carystinos, George D. "Induction of vacuolar H+-translocating pyrophosphatase during anoxia." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55483.
Full textAbstract:
Anaerobiosis results in low ATP levels and cytoplasmic acidosis. Pyrophosphate (PPi) may play an important role in anaerobiosis as an energy source replacing ATP, as suggested by the hypoxic induction of PPi:fructose 6-phosphate 1-phosphotransferase and sucrose synthase in preference to phosphofructokinase and invertase. Here we show that vacuolar H$ sp+$-translocating pyrophosphatase (PPase) is also strongly induced by anoxia in rice seedlings. The PPase transcript abundance is increased within the first hours of anoxia, and decreases within 2 days after the return of seedlings to air, similarly to alcohol dehydrogenase-1 (Adh1). However, tissue studies show that the highest transcript induction for PPase is in the root whereas the highest induction of Adh1 is in the shoot. Assays of enzyme specific activity indicate a 75-fold increase in PPase activity over 6 days of anoxia, while the vacuolar ATPase changes only slightly. Return of seedlings to air results in rapid disappearance of enzyme activity. Chilling stress in rice seedlings also gives rise to an increase in immunoreactive PPase enzyme, and a progressive 20-fold increase in enzyme specific activity within 6 days. Upon return to room temperature both enzyme level and specific activity decrease. In corn, hypoxic stress results in a small induction in the PPase transcript, and no increase in PPase specific activity, which, however, is constitutively high in this material. It is suggested that in both species, H$ sp+$-PPase may play an important role in hypoxia and chilling stress, not only in conserving ATP, but also in limiting cytoplasmic acidosis.
19
Jackson, Adele. "Oxygen sensing, plasticity and catecholaminergic functions in cultured chromaffin cells of rat carotid body and adrenal medulla : modulation by chronic hypoxia and acetylcholine receptors /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0018/NQ30096.pdf.
Full text
20
Porter, Linsey. "Regulation of granulocyte apoptosis by hypoxia and glucocorticoids." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708255.
Full text
21
Das, Rapti. "The influence of chronic hypoxia on the responses to endothelin of the pulmonary circulation of rats." Click to view the E-thesis via HKUTO, 2001. http://sunzi.lib.hku.hk/hkuto/record/B42576155.
Full text
22
Hajeri, Vinita A. Padilla Pamela Ann Fox. "Genetic and cellular analysis of anoxia-induced cell cycle arrest in Caenorhabditis elegans." [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-9776.
Full text
23
Meller, Camie Lynn. "Molecular Changes Associated with Anoxia Tolerance in Austrofundulus limnaeus embryos." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/85.
Full textAbstract:
Embryos from the annual killifish Austrofundulus limnaeus have a unique and unequalled ability among vertebrates to withstand extended periods of anoxia (maximum lethal time to 50% mortality of 65 days at 25°C). In addition, tolerance of anoxia is gained and subsequently lost during the normal development of this species. Thus, anoxia tolerant and anoxia sensitive individuals can be compared within the same species, making A. limnaeus an excellent model for studying the molecular changes associated with survival of oxygen deprivation in vertebrates. The aim of this project is to analyze the molecular changes associated with anoxia tolerance in the embryos of A. limnaeus. Understanding how the cells of these embryos become tolerant to anoxia will aid in identifying novel therapeutic targets to reduce cell death following periods of ischemia in heart, brain or other tissues. Three major analyses were used to investigate the molecular changes associated with anoxia tolerance in this species. The first was a cell cycle and cell cycle arrest analysis using flow cytometry along with an immunoblot analysis of both positive and negative regulators of cell cycle progression. The second was a cell death analysis utilizing caspase-3/7 activity as well as TUNEL staining. The third was an immunoblot analysis of three different post-translational modifers (ubiquitin, SUMO-1 and SUMO-2/3). The overall findings from this study indicate that the embryos of A. limnaeus do indeed experience some degree of cellular stress (i.e. increase in ubiquitinated proteins, increase in p53 expression, evidence of DNA damage from TUNEL staining and increases in caspase activity) in response to anoxic treatment, even in their most protective state of diapause II. However, despite these observations, the whole organisms are still able to recover from anoxia and do not succumb to death. The overall low levels of TUNEL-positive cells and caspase activity relative to the positive controls indicates that the damage accrued in response to anoxic treatment is minimal. It appears that embryos are able to either "sacrifice" a certain portion of cells or they are able to repair the damage required for resumed development following anoxia.
24
Harvey, Alexandra Juanita. "Expression of hypoxia-inducible factors during bovine preimplantation embryo development /." Title page, abstract and table of contents only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phh3410.pdf.
Full text
25
Yeung, Hang-mee. "Intermittent hypoxia mediates cardioprotection via calcium handling mechanisms." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37501057.
Full text
26
Das, Rapti. "The influence of chronic hypoxia on the responses to endothelin of thepulmonary circulation of rats." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B42576155.
Full text
27
Sarturi, Péricles Serafim. "Alterações ultra-estruturais do miocárdio determinadas pela hipoxemia crônica secundária à anemia decorrrente da insuficiência renal crônica." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/8970.
Full textAbstract:
Objetivo: Estudo transversal prospectivo para determinar as alterações ultraestruturais do miocárdio devido a hipoxemia crônica secundária à anemia decorrente da doença renal crônica em pacientes em programa dialítico. Material e métodos: Foram selecionados quatorze pacientes urêmicos, sendo doze pacientes anêmicos e dois não anêmicos em uso de eritropoietina humana recombinante. Dois pacientes não urêmicos serviram como controle. Todos os pacientes utilizaram com critério de exclusão obstrução coronariana ≥ 70% à cineangiocoronariografia. Realizaram-se biópsias de septo interventricular esquerdo do miocárdico que foram avaliadas por microscopia óptica e eletrônica de transmissão. Utilizou-se o método de Carnoy para contagem e medidas das ultraestruturas do miocárdio. Foram consideradas estatisticamente significativas as diferenças cujo valor de p fosse ≤ 0,05. Resultados: Nos 16 pacientes incluídos no estudo, a média dos hematócritos e hemoglobinas dos pacientes urêmicos e não urêmicos foram 29,3±5,4% e 46,5±0,7% e 9,5±1,9 g% e 15,5±0,35 g%, respectivamente (p< 0,05). Dos quatorze pacientes urêmicos, doze eram anêmicos e dois não anêmicos, a média dos hematócritos e hemoglobinas foram 27,7±3,7% e 39,0±4,2% e 9,0±1,3 g% e 12,8±1,7 g%, respectivamente (p<0,05). As demais variáveis: idade, sexo, fração de ejeção e outras, não diferiram entre os grupos estudados. O número de mitocôndrias foi significativamente maior quando comparou-se os grupos de pacientes urêmicos com os não urêmicos (p<0,05), o mesmo ocorrendo quando comparou-se os grupos de pacientes urêmicos anêmicos com os não anêmicos (p<0,05). Nas alterações na forma das mitocôndrias, houve diferença com significância estatística entre os grupos de pacientes urêmicos e não urêmicos (p<0,05), porém esta não ocorreu quando comparou-se os grupos de pacientes urêmicos anêmicos com os não anêmicos (p>0,05). Na análise das fibras miocárdicas observou-se alterações morfológicas das bandas Z e H comparando-se os pacientes urêmicos com os não urêmicos (p<0,05) e os pacientes urêmicos anêmicos com os não anêmicos (p<0,05). Encontrou-se uma correlação inversa e forte entre o número de mitocôndrias, com os níveis de hematócrito e hemoglobina (r=-0,70, p<0,001 e r=-0,69, p<0,001), respectivamente. Conclusões: Nesta amostra de pacientes com doença renal crônica em programa de terapia renal substitutiva e com diferentes níveis de hematócrito e hemoglobina, encontrou-se alterações ultra-estruturais, na forma e número das mitocôndrias e na morfologia das bandas Z e H das células miocárdicas, possivelmente como uma conseqüência adaptativa à hipoxemia crônica secundária a anemia decorrente da insuficiência renal crônica.
28
Elmonoufy, Nourhan. "Morphological and Hematological Responses to Hypoxia During Development in the Japanese quail, Coturnix coturnix." Thesis, University of North Texas, 2003. https://digital.library.unt.edu/ark:/67531/metadc4222/.
Full textAbstract:
Hypoxic responses in quail development differ depending upon stage, duration and level of oxygen partial pressure of embryo. Incubation was switched to/from 110mmHg partial pressure (hypoxia), to/from 150mmHg (normoxia) during different stages in development, and control was incubated in normoxia throughout. Hatchability and embryo survival resulted in no hatchlings in continuous hypoxia. Responses to various hypoxic exposures throughout development resulted in recovery/repair of hypoxic damage by hatch. Heart and body mass, beak and toe length, hemoglobin, and hematocrit were measured to determine embryo responses to hypoxia during development at days 10, 15, and hatch. Hypoxia seemed to have the most deleterious effects on eggs in continuous hypoxia. Collectively, data indicate critical developmental windows for hypoxia susceptibility, especially during mid-embryonic development.
29
Joffe, David. "Obstructive sleep apnoea the genesis of daytime somnolence and cognitive impairment : arousals, hypoxia and circadian rhythm /." Connect to full text, 1997. http://hdl.handle.net/2123/382.
Full textAbstract:
Thesis (Ph. D.)--University of Sydney, 1998.Title from title screen (viewed Apr. 15, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Dept. of Respiratory Medicine, Royal North Shore Hospital, Faculty of Medicine. Degree awarded 1998; thesis submitted 1997. Includes bibliography. Also available in print form.
30
Douglas, Donna Nabeha Carleton University Dissertation Chemistry. "Anoxia induces changes in translatable mRNA populations in Trachemys scripta elegans: a possible adaptive strategy for anoxia tolerance." Ottawa, 1993.
Find full text
31
Beickelman, Amy C. "The synthesis and biological characterization of a potential hypoxic cell sensitizer /." Connect to full text in OhioLINK ETD Center, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1197412856.
Full textAbstract:
Thesis (M.S.)--University of Toledo, 2007.Typescript. "Submitted as partial fulfillment of the requirements for The Master of Pharmaceutical Sciences." "A thesis entitled"--at head of title. Bibliography: leaves 53-55.
32
Simmons, Grant H. "Cutaneous vasodilation at simulated high altitude : impacts on human thermoregulation and vasoconstrictor function/." Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2008. http://hdl.handle.net/1794/9495.
Full text
33
Yeung, Hang-mee. "Oxidative stress, impaired calcium homeostasis and nitric oxide production in the heart of rats in chronic and intermittent hypoxia." Click to view the E-thesis via HKUTO View the Table of Contents & Abstract, 2009. http://sunzi.lib.hku.hk/hkuto/record/B4403345X.
Full text
34
Lau, Yue-huen Thomas. "Nuclear transcription factors and hypoxia-inducible genes in chronic liver hypoxia." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B31939302.
Full text
35
Hopkins, Susan Roberta. "The relationship between the hypoxic ventilatory response and arterial desaturation during heavy work." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28535.
Full textAbstract:
Arterial desaturation in fit athletes, during exercise at an
intensity greater than or equal to 90% of VO₂ max has been
reported by a number of authors yet the etiology of these changes
remain obscure. Inadequate pulmonary ventilation due to a blunted
respiratory drive, or lung mechanics has been implicated as a
factor in the etiology of this phenomenon. It was the purpose of
this experiment to investigate the relationship between arterial
desaturation and ventilatory response to hypoxia (HVR). Twelve
healthy male subjects ( age = 23.8 ± 3.6 yrs., height = 181.6 ±₋₁
5.6 cms., Weight = 73.7 ± 6.2 kg., VO₂ max = 63.2 ± 2.2 ml .kg
. -1 2 .min⁻¹) performed a five minute exercise test on a treadmill at
100% of VO₂ max. Arterial samples for pH, PCO₂, PO₂, and SaO₂
were withdrawn via an indwelling arterial cannula at rest and
every 15s throughout the exercise test. The blood gas samples
were analyzed with an Instrument Laboratories 1306 blood gas
analyzer. Ventilation and VO₂ were measured by a Beckman
metabolic measurement cart. On a separate occasion the
ventilatory response to hypoxia (HVR) was determined by recording
VE as progressive hypoxia was induced by adding N₂ to a mixing
chamber. SaO₂ was measured using a Hewlett-Packard ear oximeter; to maintain isocapnia small ammounts of CO₂ were added to the
open circuit system. ANOVA for repeated measured was used to
evaluate changes in blood gases, ventilation, and VO₂. Simple
linear regression and multiple linear regression was used to
evaluate the relationship between the changes in SaO₂ and HVR and the descriptive variables. Subjects showed a significant
decline in arterial saturation and PO₂ over the course of the
test (p < 0.01,and p < 0.01). Four subjects (Mild) exhibited
modest decreases in SaO₂ to (94.6 ± 1.9%), three (Moderate)
showed an intermediate response (SaO₂ 91.6 ± 0.1%) and five
(Marked) demonstrated a marked decrease in arterial saturation
(SaO₂ = 90.0 + 1.2%). The differences in PO₂ and SaO₂ between
Mild and Marked groups were significant ( p < 0.05, and p <
0.01); there were no significant differences between groups in
VE, VO₂, pH or PCO . There was no significant correlation between the lowest SaO₂ reached and HVR, or any of the descriptive
variables. Nine subjects did not reach maximal VE (as determined
by the VO₂ max test) on the exercise test, two subjects 2
exhibited similar ventilation, and the remaining subject exceeded maximal VE, but fell into the Mild group with respect to desaturation. Oxygen uptake exceeded that recorded for the VO₂ max determination for four of the five subjects in the Marked group; the remaining subjects demonstrated lower or similar values. It was concluded that arterial desaturation was not related to blunted hypoxic drive.Education, Faculty of
Curriculum and Pedagogy (EDCP), Department of
Graduate
36
Matheson, Gordon Omar. "Skeletal muscle metabolism during exercise : an in vivo ³¹P nuclear magnetic resonance study." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/31128.
Full textAbstract:
The metabolic and biochemical adaptations which set the endurance limit in skeletal muscle and are modified by physical training, and those which set the fatigue limits in conditions of chronic hypoxia, are not completely understood. Therefore, the purpose of this study was to measure the key metabolites involved in the control of oxidative and glycolytic metabolism, during the elevated metabolic demands of exercise, in subject groups which were separated by distinct differences in their training status or by their exposure to chronic hypobaric hypoxia. Since repeated measures of the key metabolites involved in energy metabolism (PCr, Pi, ATP) and intracellular pH (pHm) would be exceedingly difficult using the conventional muscle needle biopsy technique, ³¹P NMR was selected as an appropriate, noninvasive method for measuring these metabolites. Two separate exercise models were developed for use within a 1.0 m bore NMR machine. An electrical stimulation model using the rectus femoris muscle was developed and the factors which influenced reliability and reproducibility of the data were determined. In addition, a dynamic exercise model was developed in which the gastrocnemius muscle was exercised in a mechanical calf ergometer.
The results of the experiments using the electrical stimulation model indicate that RF coil geometry, stimulation intensity and duty cycle, electrode placement, and subject tolerance require very close control for the model to be reliable. It is felt that this model is best suited for experiments which require a within-subject design and is ideally suited for experimental or therapeutic intervention studies. The calf ergometer was used to compare sedentary lowlanders, marathon and ultramarathon runners, power trained athletes, and Quechua Indians, native to altitudes of 4,200 m in the Andes, before and after deacclimation to sea level. It was found that the Andean natives did not possess a standard physiological phenotype with respect to aerobic and anaerobic capacities. In addition, given the Andean's very low anaerobic capacity and intermediate aerobic capacity, this group performed calf work equivalent to that of highly trained endurance and power athletes. Moreover, pHm, PCr, Pi, and ATP showed equivalent perturbation at fatigue and in recovery compared with the marathon runners but considerably less perturbation than was found in the power trained athletes who possess equivalent aerobic capacities but far greater anaerobic capacities. NMR derivable estimates of the phosphorylation potential in this study support the theory that closer coupling between ATP supply-ATP demand may be responsible for reduced kinetic and thermodynamic activation of mitochondrial metabolism seen in the Andean natives.Science, Faculty of
Zoology, Department of
Graduate
37
Roy, Julianne Leslee. "The regulation and function of Thor (d4E-BP) during hypoxia in Drosophila melanogaster /." view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1276392361&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.
Full textAbstract:
Thesis (Ph. D.)--University of Oregon, 2006.Typescript. Includes vita and abstract. "This thesis includes both previously published and co-authored materials"--P. iv. Includes bibliographical references (leaves 57-63). Also available for download via the World Wide Web; free to University of Oregon users.
38
Ford, Courtney B. Wallace Richard K. "Improving tolerance to hypoxia in the eastern oyster, Crassostrea virginica." Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Summer/master's/FORD_COURTNEY_4.pdf.
Full text
39
Kiteala, Lori. "The relationship between exercise intensity, pulmonary diffusion and hemoglobin saturation in competitive endurance athletes." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26074.
Full textAbstract:
The goal of the present investigation was to evaluate the role of the pulmonary diffusion capacity (as measured by DLco) in relation to exercise-induced hypoxemia in elite athletes working at near maximal exercise intensities. Twenty-four elite cyclists were submitted to a direct measurement of VO$ sb2$ max on cycle ergometer which permitted classification into one of two groups. "Desaturaters" (N = 13) if oxyhemoglobin saturation (SaO$ sb2$%), as determined by finger oxymetry, fell below 91% or "non-desaturaters" if SaO$ sb2$% remained above 91%. Subsequent determinations of the transfer capacity for CO (DLco) were made using a 3 second breath-hold technique (Gould 2400/2450), at rest as well as at 60% and 90% of previously determined VO$ sb2$ max ($>$4.0 1/min). The results show an increase in DLco from rest to the first exercise intensity (desat: 41.7 $ pm$ 5.7 to 55.1 $ pm$ 4.7; non-desat: 41.1 $ pm$ 5.8 to 57.2 $ pm$ 6.9 mlsCO/mmHg/min) without much further increase to the maximal workload (desat: 61.0 $ pm$ 6.0; non-desat: 61.4 $ pm$ 9.5 mls CO/mmHg/min). No significant differences in DLco were found between the two groups at rest or either of the two exercise intensities. Significant differences between the desat and non-desat groups were found for FVC, post-exercise FEF$ sb{25-75 %}$, and VE/VO$ sb2$.The present results are in agreement with previous reports showing arterial desaturation in 50% of highly-trained subjects when VO$ sb2$ max $>$4.0 1/min. The present investigation cannot clearly establish the role of DLco in this response. (Abstract shortened by UMI.)
40
Yaw, Lai-ping, and 邱麗萍. "Functional role of endothelin-1 on astrocytes and neurons under hypoxia/ischemia by using ET-1 transgenic and knockout mice." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B2951180X.
Full text
41
Tam, Tin-lap Leonard, and 譚天立. "The influence of acute, chronic or chronic intermittent hypoxia on NO release from the renal circulation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B30401756.
Full text
42
Lau, Yue-huen Thomas, and 劉汝這. "Nuclear transcription factors and hypoxia-inducible genes in chronic liver hypoxia." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31939302.
Full text
43
Chan, Yuk-ling, and 陳玉玲. "Effects of hypoxia and hyperglycemia on proliferation and expression of glucose-related signaling molecules in extravillous trophoblastcell line in vitro." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41290793.
Full text
44
Yeung, Hang-mee, and 楊恆美. "Intermittent hypoxia mediates cardioprotection via calcium handling mechanisms." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37501057.
Full text
45
Hodkinson, Peter David. "Prevention of hypoxia in helicopter aircrew : acceptable compromises." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708497.
Full text
46
Pandit, Jaideep Jagdeesh. "The effects of exercise on the chemical control of breathing in man." Thesis, University of Oxford, 1993. http://ora.ox.ac.uk/objects/uuid:09156247-2a9b-4c25-b51a-7b3669d6319e.
Full textAbstract:
This thesis is concerned with the chemical control of breathing during exercise in humans. Chapter 1 reviews some of the relevant studies in animals and humans. Chapter 2 describes the experimental apparatus and the technique of dynamic end-tidal forcing performed using a computer-controlled gas-mixing system. Chapter 3 describes a study of the effects of sustained hypoxia on ventilation during steady exercise. The acute ventilatory response to hypoxia (AHR) was increased during exercise as compared with rest, but the magnitude of the subsequent decline in ventilation (HVD), expressed as a fraction of the AHR, was reduced. A simple model of the hypoxic peripheral chemoreflex is proposed, in which the mechanisms underlying AHR and HVD are functionally separate and can be independently modulated by external factors. Chapter 4 assesses changes in peripheral chemoreflex sensitivity to hypoxia in terms of the degree of decline in AHR measured in the resting periods shortly after prior conditioning periods of hypoxia and/or exercise. At rest, a second AHR measured 6 min after a period of sustained hypoxia had declined by 30% as compared with the initial AHR. In contrast, the AHR measured in the resting period after a period of sustained hypoxic exercise was only 11% smaller in magnitude than the AHR measured after a period of euoxic exercise. The results suggest that the degree to which hypoxic sensitivity declines during sustained hypoxia is genuinely attenuated, rather than masked, by exercise. Chapter 5 describes the changes in respiration during prolonged exercise breathing air with and without added CO2. During prolonged poikilocapnic exercise, ventilation remained constant, but metabolic CO2 production, respiratory quotient and end-tidal PCO2 declined; a result which suggests that in man, ventilation can be dissociated from the CO2 flux. During hypercapnic exercise, ventilation progressively increased; this was interpreted as being due to a correction by end-tidal forcing of the natural tendency for end-tidal CO2 to decline, together with an independent effect of CO2 per se on the ventilation. Chapter 6. Electrical muscle stimulation was used as means of inducing non-volitional exercise. Electrically-induced exercise increased the AHR as compared with rest, and with voluntary exercise at matched external work rate. The AHRs during electrical stimulation and voluntary exercise matched to the internal work rate were similar. Chapter 7. Electrical muscle stimulation was used in paraplegic subjects in whom there would be no neural control of exercise. Electrically-induced exercise increased the AHR as compared with rest. When compared with the data from Chapter 6, the results suggest that the observed increase in AHR during normal voluntary exercise can be wholly accounted for by the increase in metabolic CO2 production, or closely related factors. Chapter 8 presents a brief summary of the findings in this thesis.
47
Terblanche, Jonathan Steed. "A familial comparison of hypoxic sensitivity in two South-African populations." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/70079.
Full textAbstract:
Thesis (MSc)--Stellenbosch University, 2003.ENGLISH ABSTRACT: Chapter 1 presents a general literature review on the acute isocapnic hypoxic ventilatory response (HVR). The main findings from Chapter 2 indicate that our modified breathing circuit effectively measured the HVR while maintaining isocapnia. The measured ventilatory variables changed significantly with repeated short-term exposure to hypoxia over a 30-minute period, and the within- and between-day variability did not differ significantly. Furthermore, the variability in the HVR response (as measured by the coefficient of variation, (CV» amounted to approximately 27% between tests in both parameters. Repeated measures are recommended in future determinations of the HVR. In Chapter 3 the main findings were that hypoxic sensitivity does not differ between Caucasian and Xhosa sea-level populations in South Africa, and that ventilatory components in both normoxia and hypoxia differed between these two populations. Two distinct patterns of breathing were evident: shallow, rapid breathing among Xhosa subjects, and deeper, slower breathing among Caucasians. Moreover, lower arterial oxygen saturation levels during hypoxia among Xhosa subjects suggest that these two patterns of breathing differ in the effectiveness with which they oxygenate the blood. Inter-individual variation in HVR within each population is of the same high magnitude as that reported in the literature (Beall et al., 1997), further supporting the use of repeated measures in future studies. As previously reported (Sahn et al., 1977, Reeves et al., 1993), in Chapter 3 I document a significant correlation between HVR and partial pressure of end-tidal CO2 (PETCO). Future studies of HVR should consider PETCO2 as a covariate, despite the fact that my analyses of covariance (ANCOV A) showed no inter-population differences in HVR. In Chapter 4 I report that regression analysis shows that the HVR of parents is not a predictor of that of their offspring. No significant heritability was evident for any of the additional key variables of hypoxic VE ,hypoxic Sa02, and the CV for HVR, but a priori analyses showed that I tested too few subjects to be able to demonstrate heritability (or the lack thereof) conclusively by means of regression analyses. Importantly, repeatability estimates within populations (86 %) revealed that despite its high variability, the HVR is highly repeatable, and therefore remains a useful comparative research tool for studies of human adaptation to hypoxia.
AFRIKAANSE OPSOMMING: Hoofstuk 1 gee 'n algemene literatuuroorsig van die akute isokapniese hipoksiese ventilatoriese reaksie (HVR). Die hoofbevindinge uit Hoofstuk 2 dui aan dat ons gemodifiseerde asemhalingsbaan HVR effektief meet terwyl isokapniese toestande gehantaaf word. Die ventilatoriese veranderlikes gemeet, het betekenisvol verskil met herhaalde korttermyn blootstelling aan hipoksie in a 30-minuut periode, en die binne- en tussen-daagse afwykbaarheid het nie betekenisvol verskil nie. Verder het die afwykbaarheid van die HVR reaksie (soos bepaal deur die koëffisiënt van variasie (KV)) ongeveer 27 % beloop tussen toetse van beide parameters. Herhaalde metings word vir toekomstige bepalings van die HVR voorgestel. In Hoofstuk 3 was die hoofbevindinge dat hipoksiese sensitiwiteit nie verskil tussen Kaukasiese- en Xhosa- seevlak populasies in Suid-Afrika nie, en dat ventilatoriese komponente in beide normoksie en hipoksie verskillend was tussen hierdie twee populasies. Twee definitiewe asemhalingspatrone was duidelik merkbaar: vlak, vinnige asemhaling in Xhosa proefpersone, en dieper, stadiger asemhaling in Kaukasiërs. Verder het laer arteriële suurstof versadigingsvlakke gedurende hipoksie in Xhosa proefpersone daarop gedui dat hierdie twee asemhalingspatrone moontlik verskil in hul effektiwiteit om die bloed met suurstof te verryk. Inter-individuele variasie in HVR binne elke populasie was van dieselfde groot omvang as wat in die literatuur gerapporteer word (Beall et al., 1997), wat die gebruik van herhaalde metings in toekomstige studies verder ondersteun. Soos voorheen gerapporteer (Sahn et al., 1977, Reeves et al., 1993), dokumenteer ek in Hoofstuk 3 'n merkbare korrelasie tussen HVR en parsiële druk van eind-tidale CO2 (PET CO2 ). Verdere HVR studies behoort PET CO2 as a kovariant te beskou, ten spyte van die feit dat my analise van kovariansie (ANCOV A) geen inter-populasie verskille in HVR getoon het nie. In Hoofstuk 4 rapporteer ek dat regressie analise bewys dat die HVR van ouers nie 'n voorspeller van dié van hul kinders is nie. Geen betekenisvolle oorerflikheid was duidelik vir enige van die addisionele sleutelveranderlikes van hipoksiese VE ,hipoksiese Sa02, of die KV van HVR nie, maar 'n vorige analise het getoon dat ek te min proefpersone getoets het om oorerflikheid (of die gebrek daaraan) m.b.v. regressie analises te kan demonstreer. Dit is belangrik dat intra-populasie herhaalbaarheidsskattings (86 %) getoon het dat ten spyte van sy hoë afwykbaarheid, die HVR hoogs herhaalbaar is, en daarom 'n nuttige vergelykende navorsingshulpmiddel is vir studies rakende menslike aanpassing by hipoksie.
48
Blick, Christopher. "The role of hypoxia in urological malignancies." Thesis, University of Oxford, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.568065.
Full textAbstract:
Hypoxia, a state of low oxygen, is a feature of most solid tumours as a consequence of poor tumour vascularisation. The mechanisms, which allow cancer cells to survive and continue to grow in hypoxia, are coordinated by the transcription factor HIF. The tumour suppressor gene van Hippel-Lindau (vHL) that targets HIF for degradation is mutated in the vast majority of renal cell carcinomas (RCCs), highlighting the importance of hypoxia to tumour biology. There is, therefore, an important need to understand the adaptive changes mediated by hypoxia and to target this clinically. One class of genes regulated by HIF are microRNAs (miRNAs). MiRNAs are short, single stranded RNA that primarily inhibit protein expression from target m RNA. The first aim of this project was to identify novel hypoxia regulated miRNAs in bladder cancer and assess their functional significance. It was found that a number of miRNAs were induced in hypoxic conditions. The hypoxic induction of miR-210 was conserved in all cell lines tested. MiR-145 was found to be highly induced by hypoxia in RT4, a cell line derived from a low- grade, non-muscle invasive tumour. We showed that miR-145 was a novel, HIF target gene with two hypoxia response elements identified within the promoter. Functionally we found that miR-145 induces apoptosis in RT4 cells. MiR-100 was downregulated in hypoxia, but this downregulation did not involve HIF. Regulation of miR-100 was of interest, as it is known to target FGFR3, a gene commonly overexpressed or mutated in bladder cancer. Concomitant with a decrease in miR-100, both the mRNA and protein level of FGFR3 were found to increase in hypoxia in RT4 and RT112 cells. Increased FGFR3 expression in hypoxia was involved in sustaining activation of the downstream signaling targets phospho-PKB and phospho-ERK. In addition, we demonstrate a role for FGFR3 in regulating both 2D and 3D growth and of miR-100 in regulating 3D growth of RT4 cells. We also showed that miR-100 decreased the protein levels of mammalian target of rapamycin (mTOR). However, transfection of miR-l00 into RT4 cells did not affect the sensitivity of this cell line to rapamycin. The genetic and biochemical changes that occur in (hypoxic) tumours may alter their responsiveness to chemotherapeutic agents such as rapamycin. The second aim of this project was to investigate the responsiveness of RCCs to clinically approved chemotherapeutic agents, with the goal of correlating any differences in response to alterations in expression of specific genes. Although hypoxia regulated miR-100 did not affect sensitivity to rapamycin, we extended these studies and investigated the role of vHL status on response of renal cancer cell lines to sorafenib, sunitinib, rapamycin and metformin. We found that the presence of vHL increased resistance to rapamycin. Sensitivity to these drugs was also tested in 10 primary cell lines. There was varying sensitivity to these drugs across the cell lines representing the heterogeneity of renal cancer. We analysed the expression of a number of genes in the m TOR and hypoxic pathways in these tumours, we found the expression of a known hypoxic gene REDDl correlated with sensitivity to rapamycin. REDDl expression levels were also higher in tumour tissue when compared to normal renal parenchymal tissue and was associated with other prognostic markers such as CA9, miR-210 and vascular invasion suggesting a role as a diagnostic or prognostic marker and in patient selection for treatment with rapamycin.
49
Chan, Yuk-ling. "Effects of hypoxia and hyperglycemia on proliferation and expression of glucose-related signaling molecules in extravillous trophoblast cell line in vitro." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41290793.
Full text
50
Turnbull, Douglas William. "Genetic dissection of the transcriptional hypoxia response and genomic regional capture for massively parallel sequencing /." Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2008. http://hdl.handle.net/1794/9030.
Full textAbstract:
Thesis (Ph. D.)--University of Oregon, 2008.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 90-99). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.