Preferential activation of HIF-2α adaptive signalling in neuronal-like cells in response to acute hypoxia.

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Miguel A S Martín-Aragón Baudel

Full Text Available Stroke causes severe neuronal damage as disrupted cerebral blood flow starves neurons of oxygen and glucose. The hypoxia inducible factors (HIF-1α and HIF-2α orchestrate oxygen homeostasis and regulate specific aspects of hypoxic adaptation. Here we show the importance of HIF-2α dependant signalling in neuronal adaptation to hypoxic insult. PC12 and NT2 cells were differentiated into neuronal-like cells using NGF and retinoic acid, and exposed to acute hypoxia (1% O2. Gene and protein expression was analysed by qPCR and immunoblotting and the neuronal-like phenotype was examined. PC12 and NT2 differentiation promoted neurite extension and expression of neuronal markers, NSE and KCC2. Induction of HIF-1α mRNA or protein was not detected in hypoxic neuronal-like cells, however marked induction of HIF-2α mRNA and protein expression was observed. Induction of HIF-1α target genes was also not detected in response to acute hypoxia, however significant induction of HIF-2α transcriptional targets was clearly evident. Furthermore, hypoxic insult dramatically reduced both neurite number and length, and attenuated expression of neuronal markers, NSE and KCC2. This correlated with an increase in expression of the neural progenitor and stem cell-like markers, CD44 and vimentin, suggesting HIF-2α molecular mechanisms could potentially promote regression of neuronal-like cells to a stem-like state and trigger neuronal recovery following ischaemic insult. Our findings suggest the HIF-2α pathway predominates over HIF-1α signalling in neuronal-like cells following acute hypoxia.

Hypoxia and hypoglycaemia in Ewing's sarcoma and osteosarcoma: regulation and phenotypic effects of Hypoxia-Inducible Factor.

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Knowles, Helen J; Schaefer, Karl-Ludwig; Dirksen, Uta; Athanasou, Nicholas A

2010-07-16

Hypoxia regulates gene expression via the transcription factor HIF (Hypoxia-Inducible Factor). Little is known regarding HIF expression and function in primary bone sarcomas. We describe HIF expression and phenotypic effects of hypoxia, hypoglycaemia and HIF in Ewing's sarcoma and osteosarcoma. HIF-1alpha and HIF-2alpha immunohistochemistry was performed on a Ewing's tumour tissue array. Ewing's sarcoma and osteosarcoma cell lines were assessed for HIF pathway induction by Western blot, luciferase assay and ELISA. Effects of hypoxia, hypoglycaemia and isoform-specific HIF siRNA were assessed on proliferation, apoptosis and migration. 17/56 Ewing's tumours were HIF-1alpha-positive, 15 HIF-2alpha-positive and 10 positive for HIF-1alpha and HIF-2alpha. Expression of HIF-1alpha and cleaved caspase 3 localised to necrotic areas. Hypoxia induced HIF-1alpha and HIF-2alpha in Ewing's and osteosarcoma cell lines while hypoglycaemia specifically induced HIF-2alpha in Ewing's. Downstream transcription was HIF-1alpha-dependent in Ewing's sarcoma, but regulated by both isoforms in osteosarcoma. In both cell types hypoglycaemia reduced cellular proliferation by >or= 45%, hypoxia increased apoptosis and HIF siRNA modulated hypoxic proliferation and migration. Co-localisation of HIF-1alpha and necrosis in Ewing's sarcoma suggests a role for hypoxia and/or hypoglycaemia in in vivo induction of HIF. In vitro data implicates hypoxia as the primary HIF stimulus in both Ewing's and osteosarcoma, driving effects on proliferation and apoptosis. These results provide a foundation from which to advance understanding of HIF function in the pathobiology of primary bone sarcomas.

Cognition Effects of Low-Grade Hypoxia

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2016-07-01

human short-term memory . Br J Anaesth. 1971; 43(6):548–552. 3. Crow TJ, Kelman GR. Psychological effects of mild acute hypoxia. Br J Anaesth. 1973; 45...Journal Article 3. DATES COVERED (From – To) Jan 2003 – Sep 2005 4. TITLE AND SUBTITLE Cognition Effects of Low-Grade Hypoxia 5a. CONTRACT NUMBER... cognitive function are reported in this paper. The study compared cognitive function during short exposures at four different altitudes. Ninety-one

Hypoxia and hypoglycaemia in Ewing's sarcoma and osteosarcoma: regulation and phenotypic effects of Hypoxia-Inducible Factor

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Dirksen Uta

2010-07-01

Full Text Available Abstract Background Hypoxia regulates gene expression via the transcription factor HIF (Hypoxia-Inducible Factor. Little is known regarding HIF expression and function in primary bone sarcomas. We describe HIF expression and phenotypic effects of hypoxia, hypoglycaemia and HIF in Ewing's sarcoma and osteosarcoma. Methods HIF-1α and HIF-2α immunohistochemistry was performed on a Ewing's tumour tissue array. Ewing's sarcoma and osteosarcoma cell lines were assessed for HIF pathway induction by Western blot, luciferase assay and ELISA. Effects of hypoxia, hypoglycaemia and isoform-specific HIF siRNA were assessed on proliferation, apoptosis and migration. Results 17/56 Ewing's tumours were HIF-1α-positive, 15 HIF-2α-positive and 10 positive for HIF-1α and HIF-2α. Expression of HIF-1α and cleaved caspase 3 localised to necrotic areas. Hypoxia induced HIF-1α and HIF-2α in Ewing's and osteosarcoma cell lines while hypoglycaemia specifically induced HIF-2α in Ewing's. Downstream transcription was HIF-1α-dependent in Ewing's sarcoma, but regulated by both isoforms in osteosarcoma. In both cell types hypoglycaemia reduced cellular proliferation by ≥ 45%, hypoxia increased apoptosis and HIF siRNA modulated hypoxic proliferation and migration. Conclusions Co-localisation of HIF-1α and necrosis in Ewing's sarcoma suggests a role for hypoxia and/or hypoglycaemia in in vivo induction of HIF. In vitro data implicates hypoxia as the primary HIF stimulus in both Ewing's and osteosarcoma, driving effects on proliferation and apoptosis. These results provide a foundation from which to advance understanding of HIF function in the pathobiology of primary bone sarcomas.

[Study on intermittent hypoxia in children sleep apnea hypopnea syndrome model and insulin-like growth factor-1 and insulin-like growth factor binding protein-3 levels in serum].

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Hou, Jin; Yan, Jing; Kang, Quan-qing

2012-03-01

Using rats fed in intermittent hypoxia environment to study the relationship between sleep apnea hypopnea syndrome (SAHS) of children and growth retardation. The hypoxic chamber was designed and manufactured, the control of intermittent hypoxia was achieved. Twenty-four rats were randomly divided into three groups: mild and severe hypoxia group, and control group. In control group, the animals were normally fed, without interruption. The animals in other two groups were kept in the cabin, simulated mild and severe intermittent hypoxia conditions 8-hour a day, a total of 35 days. According to the results of preliminary experiments, the concentration of intermittent hypoxia and frequency were determined. The animals with mild hypoxia events occurred nearly six times per hour, the average minimum oxygen saturation dropped to 0.853, the animals with severe hypoxia events occurred nearly 24 times per hour, the average minimum oxygen saturation dropped to 0.776. Body mass and length were measured before and after experiment. The serum insulin-like growth factor (IGF)-1 and insulin-like growth factor binding protein (IGFBP)-3 expression were tested from venous blood by enzyme-linked immunosorbent assay (ELISA). The length and body mass of rats in three groups before and after experiment were not statistically different (P>0.05). Before the experiment the serum IGF-1 and IGFBP-3 levels were not significantly different (P>0.05). 35 d after the experiment, the serum IGF-1 (x±s, the same below) in the control group, mild hypoxia and severe hypoxia were (60.0±18.5) ng/ml, (40.6±9.9) ng/ml and (13.1±8.6) ng/ml, F=25.840, Phypoxia increased (Papnea hypopnea syndrome, the intermittent hypoxia in young rats does not show physical growth retardation, but the serum IGF-1, IGFBP-3 levels decreased with the increase of hypoxia and decline of oxygen saturation.

Culture media from hypoxia conditioned endothelial cells protect human intestinal cells from hypoxia/reoxygenation injury.

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Hummitzsch, Lars; Zitta, Karina; Bein, Berthold; Steinfath, Markus; Albrecht, Martin

2014-03-10

Remote ischemic preconditioning (RIPC) is a phenomenon, whereby short episodes of non-lethal ischemia to an organ or tissue exert protection against ischemia/reperfusion injury in a distant organ. However, there is still an apparent lack of knowledge concerning the RIPC-mediated mechanisms within the target organ and the released factors. Here we established a human cell culture model to investigate cellular and molecular effects of RIPC and to identify factors responsible for RIPC-mediated intestinal protection. Human umbilical vein cells (HUVEC) were exposed to repeated episodes of hypoxia (3 × 15 min) and conditioned culture media (CM) were collected after 24h. Human intestinal cells (CaCo-2) were cultured with or without CM and subjected to 90 min of hypoxia/reoxygenation injury. Reverse transcription-polymerase chain reaction, Western blotting, gelatin zymography, hydrogen peroxide measurements and lactate dehydrogenase (LDH) assays were performed. In HUVEC cultures hypoxic conditioning did not influence the profile of secreted proteins but led to an increased gelatinase activity (Pcultures 90 min of hypoxia/reoxygenation resulted in morphological signs of cell damage, increased LDH levels (Pculture model may help to unravel RIPC-mediated cellular events and to identify molecules released by RIPC. Copyright © 2014 Elsevier Inc. All rights reserved.

Radioprotective effect of exogenic hypoxia in fractionated irradiation

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Kazymbetov, P.; Yarmonenko, S.P.; Vajnson, A.A.

1988-01-01

During the experiments with mice it is established, that exogenic hypoxia protective effect (8%O 2 ), evaluated according to survival rate, decreases at the change from single to fractionated irradiation. Dose change factor (DCF) is equal to 1.55 and 1.22-1.31, respectively. Skin protection using exogenic hypoxia at the local fractionated irradiation is expressed more, than at the fractionated one. DCF is equal to 1.56 and 1.28, respectively. Exogenic hypoxia protection effect in the tumor is expressed rather weakly. DCF at single and fractionated irradiation constitutes 1.03 and 1.07-1.13, respectively. Due to skin preferential protection the therapeutic gain factor at irradiation under the exogenic hypoxia conditions constitutes 1.24 and 1.38-1.46, respectively, at single and fractionated irradiation

Gender difference in the neuroprotective effect of rat bone marrow mesenchymal cells against hypoxia-induced apoptosis of retinal ganglion cells.

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Yuan, Jing; Yu, Jian-Xiong

2016-05-01

Bone marrow mesenchymal stem cells can reduce retinal ganglion cell death and effectively prevent vision loss. Previously, we found that during differentiation, female rhesus monkey bone marrow mesenchymal stem cells acquire a higher neurogenic potential compared with male rhesus monkey bone marrow mesenchymal stem cells. This suggests that female bone marrow mesenchymal stem cells have a stronger neuroprotective effect than male bone marrow mesenchymal stem cells. Here, we first isolated and cultured bone marrow mesenchymal stem cells from female and male rats by density gradient centrifugation. Retinal tissue from newborn rats was prepared by enzymatic digestion to obtain primary retinal ganglion cells. Using the transwell system, retinal ganglion cells were co-cultured with bone marrow mesenchymal stem cells under hypoxia. Cell apoptosis was detected by flow cytometry and caspase-3 activity assay. We found a marked increase in apoptotic rate and caspase-3 activity of retinal ganglion cells after 24 hours of hypoxia compared with normoxia. Moreover, apoptotic rate and caspase-3 activity of retinal ganglion cells significantly decreased with both female and male bone marrow mesenchymal stem cell co-culture under hypoxia compared with culture alone, with more significant effects from female bone marrow mesenchymal stem cells. Our results indicate that bone marrow mesenchymal stem cells exert a neuroprotective effect against hypoxia-induced apoptosis of retinal ganglion cells, and also that female cells have greater neuroprotective ability compared with male cells.

Hypoxia silences retrotrapezoid nucleus respiratory chemoreceptors via alkalosis.

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Basting, Tyler M; Burke, Peter G R; Kanbar, Roy; Viar, Kenneth E; Stornetta, Daniel S; Stornetta, Ruth L; Guyenet, Patrice G

2015-01-14

In conscious mammals, hypoxia or hypercapnia stimulates breathing while theoretically exerting opposite effects on central respiratory chemoreceptors (CRCs). We tested this theory by examining how hypoxia and hypercapnia change the activity of the retrotrapezoid nucleus (RTN), a putative CRC and chemoreflex integrator. Archaerhodopsin-(Arch)-transduced RTN neurons were reversibly silenced by light in anesthetized rats. We bilaterally transduced RTN and nearby C1 neurons with Arch (PRSx8-ArchT-EYFP-LVV) and measured the cardiorespiratory consequences of Arch activation (10 s) in conscious rats during normoxia, hypoxia, or hyperoxia. RTN photoinhibition reduced breathing equally during non-REM sleep and quiet wake. Compared with normoxia, the breathing frequency reduction (Δf(R)) was larger in hyperoxia (65% FiO2), smaller in 15% FiO2, and absent in 12% FiO2. Tidal volume changes (ΔV(T)) followed the same trend. The effect of hypoxia on Δf(R) was not arousal-dependent but was reversed by reacidifying the blood (acetazolamide; 3% FiCO2). Δf(R) was highly correlated with arterial pH up to arterial pH (pHa) 7.5 with no frequency inhibition occurring above pHa 7.53. Blood pressure was minimally reduced suggesting that C1 neurons were very modestly inhibited. In conclusion, RTN neurons regulate eupneic breathing about equally during both sleep and wake. RTN neurons are the first putative CRCs demonstrably silenced by hypocapnic hypoxia in conscious mammals. RTN neurons are silent above pHa 7.5 and increasingly active below this value. During hyperoxia, RTN activation maintains breathing despite the inactivity of the carotid bodies. Finally, during hypocapnic hypoxia, carotid body stimulation increases breathing frequency via pathways that bypass RTN. Copyright © 2015 the authors 0270-6474/15/350527-17$15.00/0.

Suspended animation-like state protects mice from lethal hypoxia.

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Blackstone, Eric; Roth, Mark B

2007-04-01

Joseph Priestley observed the high burn rate of candles in pure oxygen and wondered if people would "live out too fast" if we were in the same environment. We hypothesize that sulfide, a natural reducer of oxygen that is made in many cell types, acts as a buffer to prevent unrestricted oxygen consumption. To test this, we administered sulfide in the form of hydrogen sulfide (H2S) to mice (Mus musculus). As we have previously shown, H2S decreases the metabolic rate of mice by approximately 90% and induces a suspended animation-like state. Mice cannot survive for longer than 20 min when exposed to 5% oxygen. However, if mice are first put into a suspended animation-like state by a 20-min pretreatment with H2S and then are exposed to low oxygen, they can survive for more than 6.5 h in 5% oxygen with no apparent detrimental effects. In addition, if mice are exposed to a 20-min pretreatment with H2S followed by 1 h at 5% oxygen, they can then survive for several hours at oxygen tensions as low as 3%. We hypothesize that prior exposure to H2S reduces oxygen demand, therefore making it possible for the mice to survive with low oxygen supply. These results suggest that H2S may be useful to prevent damage associated with hypoxia.

Hypoxia and hypoglycaemia in Ewing's sarcoma and osteosarcoma: regulation and phenotypic effects of Hypoxia-Inducible Factor

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Knowles, Helen J; Schaefer, Karl-Ludwig; Dirksen, Uta; Athanasou, Nicholas A

2010-01-01

Hypoxia regulates gene expression via the transcription factor HIF (Hypoxia-Inducible Factor). Little is known regarding HIF expression and function in primary bone sarcomas. We describe HIF expression and phenotypic effects of hypoxia, hypoglycaemia and HIF in Ewing's sarcoma and osteosarcoma. HIF-1α and HIF-2α immunohistochemistry was performed on a Ewing's tumour tissue array. Ewing's sarcoma and osteosarcoma cell lines were assessed for HIF pathway induction by Western blot, luciferase assay and ELISA. Effects of hypoxia, hypoglycaemia and isoform-specific HIF siRNA were assessed on proliferation, apoptosis and migration. 17/56 Ewing's tumours were HIF-1α-positive, 15 HIF-2α-positive and 10 positive for HIF-1α and HIF-2α. Expression of HIF-1α and cleaved caspase 3 localised to necrotic areas. Hypoxia induced HIF-1α and HIF-2α in Ewing's and osteosarcoma cell lines while hypoglycaemia specifically induced HIF-2α in Ewing's. Downstream transcription was HIF-1α-dependent in Ewing's sarcoma, but regulated by both isoforms in osteosarcoma. In both cell types hypoglycaemia reduced cellular proliferation by ≥ 45%, hypoxia increased apoptosis and HIF siRNA modulated hypoxic proliferation and migration. Co-localisation of HIF-1α and necrosis in Ewing's sarcoma suggests a role for hypoxia and/or hypoglycaemia in in vivo induction of HIF. In vitro data implicates hypoxia as the primary HIF stimulus in both Ewing's and osteosarcoma, driving effects on proliferation and apoptosis. These results provide a foundation from which to advance understanding of HIF function in the pathobiology of primary bone sarcomas

Radiation, hypoxia and genetic stimulation: implications for future therapies

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Adams, Gerald E.; Hasan, Na'il M.; Joiner, Michael C.

1997-01-01

The cellular stress response, whereby very low doses of cytotoxic agents induce resistance to much higher doses, is an evolutionary defence mechanism and is stimulated following challenges by numerous chemical, biological and physical agents including particularly radiation, drugs, heat and hypoxia. There is much homology in the effects of these agents which are manifest through the up-regulation of various genetic pathways. Low-dose radiation stress influences processes involved in cell-cycle control, signal transduction pathways, radiation sensitivity, changes in cell adhesion and cell growth. There is also homology between radiation and other cellular stress agents, particularly hypoxia. Whereas traditionally, hypoxia was regarded mainly as an agent conferring resistance to radiation, there is now much evidence illustrating the cytokine-like properties of hypoxia as well as radiation. Stress phenomena are likely to be important in risks arising from low doses of radiation. Conversely, exploitation of the stress response in settings appropriate to therapy can be particularly beneficial not only in regard to radiation alone but in combinations of radiation and drugs. Similarly, tissue hypoxia can be exploited in novel ways of enhancing therapeutic efficacy. Bioreductive drugs, which are cytotoxically activated in hypoxic regions of tissue, can be rendered even more effective by hypoxia-induced increased expression of enzyme reductases. Nitric oxide pathways are influenced by hypoxia thereby offering possibilities for novel vascular based therapies. Other approaches are discussed

Characterization of CgHIFα-Like, a Novel bHLH-PAS Transcription Factor Family Member, and Its Role under Hypoxia Stress in the Pacific Oyster Crassostrea gigas.

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Ting Wang

Full Text Available Hypoxia-inducible factor (HIF, a critical member of the basic-helix-loop-helix (bHLH-containing Per-Arnt-Sim (PAS protein family, is a master transcription factor involved in maintaining oxygen homeostasis. In the present study, we isolated and characterized a novel bHLH-PAS family member, CgHIFα-like gene, from the Pacific oyster Crassostrea gigas, and determined its importance during hypoxia stress. The 3020-bp CgHIFα-like cDNA encoded a protein of 888 amino acids. The predicted CgHIFα-like amino acid sequence was conserved in the N-terminal bHLH, PAS, and PAC domains (but not in the C-terminal domain and was most closely related to the HIF family in the bHLH-PAS protein phylogenic tree. Similar to the mammalian HIF-1α, CgHIFα-like could be expressed as four mRNA isoforms containing alternative 5'-untranslated regions and different translation initiation codons. At the mRNA level, these isoforms were expressed in a tissue-specific manner and showed increased transcription to varying degrees under hypoxic conditions. Additionally, the western blot analysis demonstrated that CgHIFα-like was induced by hypoxia. Electrophoretic mobility shift assay indicated that CgHIFα-like could bind to the hypoxia responsive element (HRE, whereas dual-luciferase reporter analysis demonstrated that CgHIFα-like could transactivate the reporter gene containing the HREs. In addition to CgHIFα-like, we identified CgARNT from the C. gigas, analyzed its expression pattern, and confirmed its interaction with CgHIFα-like using a yeast two-hybrid assay. In conclusion, this is the first report on the cloning and characterization of a novel hypoxia transcription factor in mollusks, which could accumulate under hypoxia and regulate hypoxia related gene expression by binding to HRE and dimerizing with CgARNT. As only one member of HIF has been identified in invertebrates to date, our results provide new insights into the unique mechanisms of hypoxia tolerance in

Intermittent hypoxia training in prediabetes patients: Beneficial effects on glucose homeostasis, hypoxia tolerance and gene expression.

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Serebrovska, Tetiana V; Portnychenko, Alla G; Drevytska, Tetiana I; Portnichenko, Vladimir I; Xi, Lei; Egorov, Egor; Gavalko, Anna V; Naskalova, Svitlana; Chizhova, Valentina; Shatylo, Valeriy B

2017-09-01

The present study aimed at examining beneficial effects of intermittent hypoxia training (IHT) under prediabetic conditions. We investigate the effects of three-week IHT on blood glucose level, tolerance to acute hypoxia, and leukocyte mRNA expression of hypoxia inducible factor 1α (HIF-1α) and its target genes, i.e. insulin receptor, facilitated glucose transporter-solute carrier family-2, and potassium voltage-gated channel subfamily J. Seven healthy and 11 prediabetic men and women (44-70 years of age) were examined before, next day and one month after three-week IHT (3 sessions per week, each session consisting 4 cycles of 5-min 12% O 2 and 5-min room air breathing). We found that IHT afforded beneficial effects on glucose homeostasis in patients with prediabetes reducing fasting glucose and during standard oral glucose tolerance test. The most pronounced positive effects were observed at one month after IHT termination. IHT also significantly increased the tolerance to acute hypoxia (i.e. SaO 2 level at 20th min of breathing with 12% O 2 ) and improved functional parameters of respiratory and cardiovascular systems. IHT stimulated HIF-1α mRNA expression in blood leukocytes in healthy and prediabetic subjects, but in prediabetes patients the maximum increase was lagged. The greatest changes in mRNA expression of HIF-1α target genes occurred a month after IHT and coincided with the largest decrease in blood glucose levels. The higher expression of HIF-1α was positively associated with higher tolerance to hypoxia and better glucose homeostasis. In conclusion, our results suggest that IHT may be useful for preventing the development of type 2 diabetes. Impact statement The present study investigated the beneficial effects of intermittent hypoxia training (IHT) in humans under prediabetic conditions. We found that three-week moderate IHT induced higher HIF-1α mRNA expressions as well as its target genes, which were positively correlated with higher tolerance

Decreased extracellular adenosine levels lead to loss of hypoxia-induced neuroprotection after repeated episodes of exposure to hypoxia.

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Mei Cui

Full Text Available Achieving a prolonged neuroprotective state following transient ischemic attacks (TIAs is likely to effectively reduce the brain damage and neurological dysfunction associated with recurrent stroke. HPC is a phenomenon in which advanced exposure to mild hypoxia reduces the stroke volume produced by a subsequent TIA. However, this neuroprotection is not long-lasting, with the effects reaching a peak after 3 days. Therefore, in this study, we investigated the use of multiple episodes of hypoxic exposure at different time intervals to induce longer-term protection in a mouse stroke model. C57BL/6 mice were subjected to different hypoxic preconditioning protocols: a single episode of HPC or five identical episodes at intervals of 3 days (E3d HPC or 6 days (E6d HPC. Three days after the last hypoxic exposure, temporary middle cerebral artery occlusion (MCAO was induced. The effects of these HPC protocols on hypoxia-inducible factor (HIF regulated gene mRNA expression were measured by quantitative PCR. Changes in extracellular adenosine concentrations, known to exert neuroprotective effects, were also measured using in vivo microdialysis and high pressure liquid chromatography (HPLC. Neuroprotection was provided by E6d HPC but not E3d HPC. HIF-regulated target gene expression increased significantly following all HPC protocols. However, E3d HPC significantly decreased extracellular adenosine and reduced cerebral blood flow in the ischemic region with upregulated expression of the adenosine transporter, equilibrative nucleoside transporter 1 (ENT1. An ENT1 inhibitor, propentofylline increased the cerebral blood flow and re-established neuroprotection in E3d HPC. Adenosine receptor specific antagonists showed that adenosine mainly through A1 receptor mediates HPC induced neuroprotection. Our data indicate that cooperation of HIF-regulated genes and extracellular adenosine is necessary for HPC-induced neuroprotection.

Effects of hypoxia on human cancer cell line chemosensitivity

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2013-01-01

Background Environment inside even a small tumor is characterized by total (anoxia) or partial oxygen deprivation, (hypoxia). It has been shown that radiotherapy and some conventional chemotherapies may be less effective in hypoxia, and therefore it is important to investigate how different drugs act in different microenvironments. In this study we perform a large screening of the effects of 19 clinically used or experimental chemotherapeutic drugs on five different cell lines in conditions of normoxia, hypoxia and anoxia. Methods A panel of 19 commercially available drugs: 5-fluorouracil, acriflavine, bortezomib, cisplatin, digitoxin, digoxin, docetaxel, doxorubicin, etoposide, gemcitabine, irinotecan, melphalan, mitomycin c, rapamycin, sorafenib, thalidomide, tirapazamine, topotecan and vincristine were tested for cytotoxic activity on the cancer cell lines A2780 (ovarian), ACHN (renal), MCF-7 (breast), H69 (SCLC) and U-937 (lymphoma). Parallel aliquots of the cells were grown at different oxygen pressures and after 72 hours of drug exposure viability was measured with the fluorometric microculture cytotoxicity assay (FMCA). Results Sorafenib, irinotecan and docetaxel were in general more effective in an oxygenated environment, while cisplatin, mitomycin c and tirapazamine were more effective in a low oxygen environment. Surprisingly, hypoxia in H69 and MCF-7 cells mostly rendered higher drug sensitivity. In contrast ACHN appeared more sensitive to hypoxia, giving slower proliferating cells, and consequently, was more resistant to most drugs. Conclusions A panel of standard cytotoxic agents was tested against five different human cancer cell lines cultivated at normoxic, hypoxic and anoxic conditions. Results show that impaired chemosensitivity is not universal, in contrast different cell lines behave different and some drugs appear even less effective in normoxia than hypoxia. PMID:23829203

Neutralizing S1P inhibits intratumoral hypoxia, induces vascular remodelling and sensitizes to chemotherapy in prostate cancer

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Ader, Isabelle; Golzio, Muriel; Andrieu, Guillaume; Zalvidea, Santiago; Richard, Sylvain; Sabbadini, Roger A.; Malavaud, Bernard; Cuvillier, Olivier

2015-01-01

Hypoxia promotes neovascularization, increased tumor growth, and therapeutic resistance. The transcription factor, hypoxia-inducible factor 1α (HIF-1α), has been reported as the master driver of adaptation to hypoxia. We previously identified the sphingosine kinase 1/sphingosine 1-phosphate (SphK1/S1P) pathway as a new modulator of HIF-1α under hypoxia. Taking advantage of a monoclonal antibody neutralizing extracellular S1P (sphingomab), we report that inhibition of S1P extracellular signaling blocks HIF-1α accumulation and activity in several cancer cell models exposed to hypoxia. In an orthotopic xenograft model of prostate cancer, we show that sphingomab reduces hypoxia and modifies vessel architecture within 5 days of treatment, leading to increased intratumoral blood perfusion. Supporting the notion that a transient vascular normalization of tumor vessels is the mechanism by which sphingomab exerts its effects, we demonstrate that administration of the antibody for 5 days before chemotherapy is more effective at local tumor control and metastatic dissemination than any other treatment scheduling. These findings validate sphingomab as a potential new normalization agent that could contribute to successful sensitization of hypoxic tumors to chemotherapy. PMID:25915662

Modulation of radioprotective effects of respiratory hypoxia by changing the duration of hypoxia before irradiation and by combining hypoxia and administration of hemopoiesis-stimulating agents

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Vacek, A.; Hofer, M.

2001-01-01

Aim: Analysis of radioprotective effect of respiratory hypoxia on hemopoietic tissue and enhancement of this effect by hemopoietic activation. Material and methods: In mice breathing hypoxic gas mixture during total body gamma irradiation the recovery of pluripotent and committed granulocyte-macrophage progenitor cells and animal lethality were determined. Results: In mice forced to breathe 10% O 2 and 8% O 2 during irradiation, the oxygen tension in the spleen decreased to 40% and 20%, respectively, of control values. Hypoxia mitigated the lethal effect of gamma-rays and improved the recovery of hemopoiesis in compartments of pluripotent and committed progenitor cells. Enhancement of the proliferative activity in hemopoietic tissue by a cytokine (rmGM-CSF) or an immunomodulator (dextran sulfate) increased the effect of hypoxic radioprotection, while elimination of proliferative cells by hydroxyurea decreased the radioprotective effect. Adaptation of experimental animals to hypoxic conditions was found to reduce the radioprotective effect without influencing tissue partial oxygen pressure lowered by hypoxic conditions. Conclusion: The data presented confirm the radioprotective effect of 10% and 8% O 2 respiratory hypoxia on hemopoiesis. These findings may represent a way out for further experimental and clinical research aimed at considering differential protection of various tissues by hypoxia. (orig.) [de

Induction of gastrin expression in gastrointestinal cells by hypoxia or cobalt is independent of hypoxia-inducible factor (HIF).

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Xiao, Lin; Kovac, Suzana; Chang, Mike; Shulkes, Arthur; Baldwin, Graham S; Patel, Oneel

2012-07-01

Gastrin and its precursors have been shown to promote mitogenesis and angiogenesis in gastrointestinal tumors. Hypoxia stimulates tumor growth, but its effect on gastrin gene regulation has not been examined in detail. Here we have investigated the effect of hypoxia on the transcription of the gastrin gene in human gastric cancer (AGS) cells. Gastrin mRNA was measured by real-time PCR, gastrin peptides were measured by RIA, and gastrin promoter activity was measured by dual-luciferase reporter assay. Exposure to a low oxygen concentration (1%) increased gastrin mRNA concentrations in wild-type AGS cells (AGS) and in AGS cells overexpressing the gastrin receptor (AGS-cholecystokinin receptor 2) by 2.1 ± 0.4- and 4.1 ± 0.3-fold (P factor hypoxia-inducible factor 1 (HIF-1) or knockdown of either the HIF-1α or HIF-1β subunit did not affect gastrin promoter inducibility under hypoxia indicated that the hypoxic activation of the gastrin gene is likely HIF independent. Mutational analysis of previously identified Sp1 regulatory elements in the gastrin promoter also failed to abrogate the induction of promoter activity by hypoxia. The observations that hypoxia up-regulates the gastrin gene in AGS cells by HIF-independent mechanisms, and that this effect is enhanced by the presence of gastrin receptors, provide potential targets for gastrointestinal cancer therapy.

Developmental Hypoxia Has Negligible Effects on Long-Term Hypoxia Tolerance and Aerobic Metabolism of Atlantic Salmon (Salmo salar).

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Wood, Andrew T; Clark, Timothy D; Andrewartha, Sarah J; Elliott, Nicholas G; Frappell, Peter B

Exposure to developmental hypoxia can have long-term impacts on the physiological performance of fish because of irreversible plasticity. Wild and captive-reared Atlantic salmon (Salmo salar) can be exposed to hypoxic conditions during development and continue to experience fluctuating oxygen levels as juveniles and adults. Here, we examine whether developmental hypoxia impacts subsequent hypoxia tolerance and aerobic performance of Atlantic salmon. Individuals at 8°C were exposed to 50% (hypoxia) or 100% (normoxia) dissolved oxygen (DO) saturation (as percent of air saturation) from fertilization for ∼100 d (800 degree days) and then raised in normoxic conditions for a further 15 mo. At 18 mo after fertilization, aerobic scope was calculated in normoxia (100% DO) and acute (18 h) hypoxia (50% DO) from the difference between the minimum and maximum oxygen consumption rates ([Formula: see text] and [Formula: see text], respectively) at 10°C. Hypoxia tolerance was determined as the DO at which loss of equilibrium (LOE) occurred in a constantly decreasing DO environment. There was no difference in [Formula: see text], [Formula: see text], or aerobic scope between fish raised in hypoxia or normoxia. There was some evidence that hypoxia tolerance was lower (higher DO at LOE) in hypoxia-raised fish compared with those raised in normoxia, but the magnitude of the effect was small (12.52% DO vs. 11.73% DO at LOE). Acute hypoxia significantly reduced aerobic scope by reducing [Formula: see text], while [Formula: see text] remained unchanged. Interestingly, acute hypoxia uncovered individual-level relationships between DO at LOE and [Formula: see text], [Formula: see text], and aerobic scope. We discuss our findings in the context of developmental trajectories and the role of aerobic performance in hypoxia tolerance.

Anti-apoptotic effect of heat shock protein 90 on hypoxia-mediated cardiomyocyte damage is mediated via the phosphatidylinositol 3-kinase/AKT pathway.

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Wang, Wei; Peng, Yizhi; Wang, Yuanyuan; Zhao, Xiaohui; Yuan, Zhiqiang

2009-09-01

1. Hypoxia-induced cardiomyocyte apoptosis contributes significantly to cardiac dysfunction following trauma, shock and burn injury. There is evidence that heat shock protein (HSP) 90 is anti-apoptotic in cardiomyocytes subjected to a variety of apoptotic stimuli. Because HSP90 acts as an upstream regulator of the serine/threonine protein kinase Akt survival pathway during cellular stress, we hypothesized that HSP90 exerts a cardioprotective effect via the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway. 2. Neonatal rat cardiomyocytes were subjected to normoxia or hypoxia in the absence or presence of the HSP90 inhibitor geldanamycin (1 μg/mL). Cardiomyocyte apoptosis was assessed by release of lactate dehydrogenase (LDH), terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling (TUNEL) staining and caspase 3 activity. Expression of HSP90, Akt, Bad and cytochrome c release was determined by western blot analysis. 3. Following exposure of cells to hypoxia, HSP90 was markedly elevated in a time-dependent manner, reaching a peak at 6 h (eightfold increase). Geldanamycin significantly increased hypoxia-induced release of LDH by 114%, the percentage of apoptotic cardiomyocytes by 102% and caspase 3 activity by 78%. Pretreatment of cells with geldanamycin also suppressed phosphorylation of both Akt and its downstream target Bad, but promoted the mitochondrial release of cytochrome c. 4. In conclusion, HSP90 activity is enhanced in cardiomyocytes following hypoxic insult. The anti-apoptotic effect of HSP90 on cardiomyocytes subjected to hypoxia is mediated, at least in part, by the PI3-K/Akt pathway. Key words: apoptosis, cardiomyocyte, heart failure, heat shock protein 90, hypoxia, phosphatidylinositol 3-kinase/Akt signalling pathway, serine/threonine protein kinase Akt.

Role of hypoxia and growth and differentiation factor-5 on differentiation of human mesenchymal stem cells towards intervertebral nucleus pulposus-like cells

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JV Stoyanov

2011-06-01

Full Text Available There is evidence that mesenchymal stem cells (MSCs can differentiate towards an intervertebral disc (IVD-like phenotype. We compared the standard chondrogenic protocol using transforming growth factor beta-1 (TGFß to the effects of hypoxia, growth and differentiation factor-5 (GDF5, and coculture with bovine nucleus pulposus cells (bNPC. The efficacy of molecules recently discovered as possible nucleus pulposus (NP markers to differentiate between chondrogenic and IVD-like differentiation was evaluated. MSCs were isolated from human bone marrow and encapsulated in alginate beads. Beads were cultured in DMEM (control supplemented with TGFß or GDF5 or under indirect coculture with bNPC. All groups were incubated at low (2 % or normal (20 % oxygen tension for 28 days. Hypoxia increased aggrecan and collagen II gene expression in all groups. The hypoxic GDF5 and TGFß groups demonstrated most increased aggrecan and collagen II mRNA levels and glycosaminoglycan accumulation. Collagen I and X were most up-regulated in the TGFß groups. From the NP markers, cytokeratin-19 was expressed to highest extent in the hypoxic GDF5 groups; lowest expression was observed in the TGFß group. Levels of forkhead box F1 were down-regulated by TGFß and up-regulated by coculture with bNPC. Carbonic anhydrase 12 was also down-regulated in the TGFß group and showed highest expression in the GDF5 group cocultured with bNPC under hypoxia. Trends in gene expression regulation were confirmed on the protein level using immunohistochemistry. We conclude that hypoxia and GDF5 may be suitable for directing MSCs towards the IVD-like phenotype.

Recombinant adeno-associated virus-delivered hypoxia-inducible stanniocalcin-1 expression effectively inhibits hypoxia-induced cell apoptosis in cardiomyocytes.

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Shi, Xin; Wang, Jianzhong; Qin, Yan

2014-12-01

Ischemia/hypoxia-induced oxidative stress is detrimental for the survival of cardiomyocytes and cardiac function. Stanniocalcin-1 (STC-1), a glycoprotein, has been found to play an inhibitory role in the production of reactive oxygen species (ROS). Here, we speculated that the overexpression of STC-1 might alleviate oxidative damage in cardiomyocytes under conditions of hypoxia. To control the expression of STC-1 in hypoxia, we constructed a recombinant adeno-associated virus (AAV) carrying the hypoxia-responsive element (HRE) to mediate hypoxia induction. Cardiomyocytes were infected with AAV-HRE-STC-1 and cultured in normoxic or hypoxic conditions, and STC-1 overexpression was only detected in hypoxic cultured cardiomyocytes by using quantitative real-time polymerase chain reaction and Western blot analysis. Using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, AAV-HRE-STC-1 infection was shown to significantly enhance cell survival under hypoxia. Hypoxia-induced cell apoptosis was inhibited by AAV-HRE-STC-1 infection by using the Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide apoptosis assay. Moreover, the proapoptotic protein Caspase-3 and anti-apoptotic protein Bcl-2, which were dysregulated by hypoxia, were reversed by AAV-HRE-STC-1 infection. AAV-HRE-STC-1-mediated STC-1 overexpression markedly inhibited ROS production in cardiomyocytes cultured under hypoxic conditions. AAV-HRE-STC-1 infection significantly upregulated uncoupled protein 3 (UCP3), whereas silencing of UCP3 blocked the inhibitory effect of AAV-HRE-STC-1 on ROS production. In contrast, AAV-HRE-STC-1 infection had no effect on UCP2, and knockdown of UCP2 did not block the inhibitory effect of AAV-HRE-STC-1 on ROS production in the cardiomyocytes cultured under hypoxic conditions. Taken together, STC1 activates antioxidant pathway in cardiomyocytes through the induction of UCP3, implying that AAV-HRE-STC-1 has potential in the treatment of ischemic

The Effect of Inspiratory Resistance on Exercise Performance and Perception in Moderate Normobaric Hypoxia.

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Seo, Yongsuk; Vaughan, Jeremiah; Quinn, Tyler D; Followay, Brittany; Roberge, Raymond; Glickman, Ellen L; Kim, Jung-Hyun

2017-12-01

Seo, Yongsuk, Jeremiah Vaughan, Tyler D. Quinn, Brittany Followay, Raymond Roberge, Ellen L. Glickman, and Jung-Hyun Kim. The effect of inspiratory resistance on exercise performance and perception in moderate normobaric hypoxia. High Alt Med Biol. 18:417-424, 2017. Respirators are simple and efficient in protecting workers against toxic airborne substances; however, their use may limit the physical performance of workers. The purpose of this study was to determine the effect of inspiratory resistance on physical performance and breathing perception in normobaric hypoxia. Nine healthy men wore a tight-fitting respiratory mask outfitted with one of four different inspiratory resistors (R) (0, 1.5, 4.5, 7.5 cm H 2 O/L/Sec) while exercising at normobaric hypoxia (17% O 2 ) at submaximal exercise workloads of 50, 100, and 150 W on a cycle ergometer for 10 minutes each, followed by a maximal oxygen uptake (VO 2 max) test to exhaustion. Maximal power output at R7.5 was significantly lower than R0 (p = 0.016) and R1.5 (p = 0.035). Respiration rate was significantly reduced at R4.5 (p = 0.011) and R7.5 (p ≤ 0.001) compared with R0. Minute ventilation was significantly decreased in R7.5 compared with R0 (p = 0.003), R1.5 (p = 0.010), and R4.5 (p = 0.016), whereas VO 2 was not significantly changed. Breathing comfort (BC) and breathing effort (BE) were significantly impaired in R7.5 (BC: p = 0.025, BE: p = 0.001) and R4.5 (BC: p = 0.007, BE: p = 0.001) compared with R0, but rating of perceived exertion (RPE) remained unchanged. Added inspiratory resistance limited maximal power output and increased perceptions of BC and BE in normobaric hypoxia. However, low-to-moderate inspiratory resistance did not have a deleterious effect on VO 2 or RPE at submaximal or maximal exercise. Perceptual and physiological characteristics of respirators of varying inspiratory resistances should be considered by manufacturers and end users during

Effects of changes in nutrient loading and composition on hypoxia dynamics and internal nutrient cycling of a stratified coastal lagoon

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Zhu, Yafei; McCowan, Andrew; Cook, Perran L. M.

2017-10-01

The effects of changes in catchment nutrient loading and composition on the phytoplankton dynamics, development of hypoxia and internal nutrient dynamics in a stratified coastal lagoon system (the Gippsland Lakes) were investigated using a 3-D coupled hydrodynamic biogeochemical water quality model. The study showed that primary production was equally sensitive to changed dissolved inorganic and particulate organic nitrogen loads, highlighting the need for a better understanding of particulate organic matter bioavailability. Stratification and sediment carbon enrichment were the main drivers for the hypoxia and subsequent sediment phosphorus release in Lake King. High primary production stimulated by large nitrogen loading brought on by a winter flood contributed almost all the sediment carbon deposition (as opposed to catchment loads), which was ultimately responsible for summer bottom-water hypoxia. Interestingly, internal recycling of phosphorus was more sensitive to changed nitrogen loads than total phosphorus loads, highlighting the potential importance of nitrogen loads exerting a control over systems that become phosphorus limited (such as during summer nitrogen-fixing blooms of cyanobacteria). Therefore, the current study highlighted the need to reduce both total nitrogen and total phosphorus for water quality improvement in estuarine systems.

Effects of changes in nutrient loading and composition on hypoxia dynamics and internal nutrient cycling of a stratified coastal lagoon

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Y. Zhu

2017-10-01

Full Text Available The effects of changes in catchment nutrient loading and composition on the phytoplankton dynamics, development of hypoxia and internal nutrient dynamics in a stratified coastal lagoon system (the Gippsland Lakes were investigated using a 3-D coupled hydrodynamic biogeochemical water quality model. The study showed that primary production was equally sensitive to changed dissolved inorganic and particulate organic nitrogen loads, highlighting the need for a better understanding of particulate organic matter bioavailability. Stratification and sediment carbon enrichment were the main drivers for the hypoxia and subsequent sediment phosphorus release in Lake King. High primary production stimulated by large nitrogen loading brought on by a winter flood contributed almost all the sediment carbon deposition (as opposed to catchment loads, which was ultimately responsible for summer bottom-water hypoxia. Interestingly, internal recycling of phosphorus was more sensitive to changed nitrogen loads than total phosphorus loads, highlighting the potential importance of nitrogen loads exerting a control over systems that become phosphorus limited (such as during summer nitrogen-fixing blooms of cyanobacteria. Therefore, the current study highlighted the need to reduce both total nitrogen and total phosphorus for water quality improvement in estuarine systems.

[Effect of intermittent hypoxia of sleep apnea on embryonic rat cortical neurons in vitro].

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Zhang, Chanjuan; Li, Yanzhong; Wang, Yan

2015-05-01

To investigate the effects of different pattens of intermittent hypoxia on the activity and apoptosis of primary cultured rat embryonic cortical neurons, and to evaluate the role of intermittent hypoxia in the mechanism of obstructive sleep syndrom induced cognitive function loss. The embryonic cerebral cortical neurons were cultured in vitro and were identified by immunofluorescence. Cultured neurons were randomly divided into intermittent hypoxia group, intermittent normal oxygen group, persistent hypoxia group and the control group, and intermittent hypoxia group was divided into five subgroups according to different frequency and time-bound. Neurons were exposed in different modes of hypoxia. MTT colorimetry was used to detect the viability of the neurons, and DAPI colorated measurement was used to calculate the percentages of neuron apoptosis. There were significantly different effects between all subgroups of intermittent hypoxia and the continued hypoxia group on neuronal activity and apoptosis (P Intermittent hypoxia groups with different frequency and time had no difference in neuronal activity and apoptosis (P > 0.05). The effect of intermittent hypoxia was more serious than that of continued hypoxia on neuronal activity and apoptosis; The impact of intermittent hypoxia on neuronal activity and apoptosis may be an important factor in obstructive sleep apnea related cognitive impairment.

Effects of hypoxia on serum hepatic chemistries of Tibet chicken and ...

African Journals Online (AJOL)

Hypoxia is a major factor that affects the subsistence and development of multicellular organisms. Tibet chicken, as a unique native chicken breed in altiplano, shows genetic adaptation to hypoxia comparing with the breeds at the low altitude. In the present study, to explore effects of hypoxia on chicken fetal livers, eggs of ...

Little effects of Insulin-like Growth Factor-I on testicular atrophy induced by hypoxia

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Casares Amelia

2006-02-01

Full Text Available Abstract Background Insulin-like Growth Factor-I (IGF-I supplementation restores testicular atrophy associated with advanced liver cirrhosis that is a condition of IGF-I deficiency. The aim of this work was to evaluate the effect of IGF-I in rats with ischemia-induced testicular atrophy (AT without liver disease and consequently with normal serum level of IGF-I. Methods Testicular atrophy was induced by epinephrine (1, 2 mg/Kg intra-scrotal injection five times per week during 11 weeks. Then, rats with testicular atrophy (AT were divided into two groups (n = 10 each: untreated rats (AT receiving saline sc, and AT+IGF, which were treated with IGF-I (2 μg.100 g b.w.-1.day-1, sc. for 28d. Healthy controls (CO, n = 10 were studied in parallel. Animals were sacrificed on day 29th. Hypophyso-gonadal axis, IGF-I and IGFBPs levels, testicular morphometry and histopathology, immuno-histochemical studies and antioxidant enzyme activity phospholipid hydroperoxide glutathione peroxidase (PHGPx were assessed. Results Compared to controls, AT rats displayed a reduction in testicular size and weight, with histological testicular atrophy, decreased cellular proliferation and transferrin expression, and all of these alterations were slightly improved by IGF-I at low doses. IGF-I therapy increased signifincantly steroidogenesis and PHGPx activity (p Conclusion In testicular atrophy by hypoxia, condition without IGF-I deficiency, IGF-treatment induces only partial effects. These findings suggest that IGF-I therapy appears as an appropriate treatment in hypogonadism only when this is associated to conditions of IGF-I deficiency (such as Laron Syndrom or liver cirrhosis.

Ethanol extract of Portulaca oleracea L. protects against hypoxia-induced neuro damage through modulating endogenous erythropoietin expression.

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Wanyin, Wang; Liwei, Dong; Lin, Jia; Hailiang, Xin; Changquan, Ling; Min, Li

2012-04-01

In addition to its role in erythropoiesis, erythropoietin is also appreciated for its neuroprotective effects, and it has been suggested for treatment of some ischemic-hypoxic neurovascular diseases. The protective effects of endogenous erythropoietin in the brain give rise to the hypothesis that modulating erythropoietin expression might be a better way for treatment of ischemia-hypoxia neurovascular diseases. We have found that ethanol extract of Portulaca oleracea L. (EEPO) could increase erythropoietin expression in hypoxic mouse brain in our previous study. The present study is to investigate whether EEPO exerts its neuroprotective effects against hypoxia injury through regulating endogenous erythropoietin expression. The results demonstrated that EEPO decreased the serum neuron specific enolase level in hypoxia mice and the activity of caspase-3 in neuron, increased the neuron viability and attenuated the pathological damages caused by the hypoxia condition. Importantly, we also found that EEPO stimulated the endogenous erythropoietin expression at both mRNA and protein levels. Using the conditioned medium containing soluble erythropoietin receptor, we found that the neuroprotective effects of EEPO were dependent, at least partly, on erythropoietin expression. Although EEPO did not affect transcription of hypoxia inducible factor-1α (HIF-1α), it did stabilize expression of HIF-1α. It is concluded that EEPO has neuroprotective effects against hypoxia injury, which is at least partly through stimulating endogenous erythropoietin expression by stabilizing HIF-1α. Copyright © 2012 Elsevier Inc. All rights reserved.

Effect of acute exposure to moderate altitude on muscle power: hypobaric hypoxia vs. normobaric hypoxia.

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Belén Feriche

Full Text Available When ascending to a higher altitude, changes in air density and oxygen levels affect the way in which explosive actions are executed. This study was designed to compare the effects of acute exposure to real or simulated moderate hypoxia on the dynamics of the force-velocity relationship observed in bench press exercise. Twenty-eight combat sports athletes were assigned to two groups and assessed on two separate occasions: G1 (n = 17 in conditions of normoxia (N1 and hypobaric hypoxia (HH and G2 (n = 11 in conditions of normoxia (N2 and normobaric hypoxia (NH. Individual and complete force-velocity relationships in bench press were determined on each assessment day. For each exercise repetition, we obtained the mean and peak velocity and power shown by the athletes. Maximum power (Pmax was recorded as the highest P(mean obtained across the complete force-velocity curve. Our findings indicate a significantly higher absolute load linked to P(max (∼ 3% and maximal strength (1 RM (∼ 6% in G1 attributable to the climb to altitude (P<0.05. We also observed a stimulating effect of natural hypoxia on P(mean and P(peak in the middle-high part of the curve (≥ 60 kg; P<0.01 and a 7.8% mean increase in barbell displacement velocity (P<0.001. No changes in any of the variables examined were observed in G2. According to these data, we can state that acute exposure to natural moderate altitude as opposed to simulated normobaric hypoxia leads to gains in 1 RM, movement velocity and power during the execution of a force-velocity curve in bench press.

Effects of intermittent hypoxia on running economy.

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Burtscher, M; Gatterer, H; Faulhaber, M; Gerstgrasser, W; Schenk, K

2010-09-01

We investigated the effects of two 5-wk periods of intermittent hypoxia on running economy (RE). 11 male and female middle-distance runners were randomly assigned to the intermittent hypoxia group (IHG) or to the control group (CG). All athletes trained for a 13-wk period starting at pre-season until the competition season. The IHG spent additionally 2 h at rest on 3 days/wk for the first and the last 5 weeks in normobaric hypoxia (15-11% FiO2). RE, haematological parameters and body composition were determined at low altitude (600 m) at baseline, after the 5 (th), the 8 (th) and the 13 (th) week of training. RE, determined by the relative oxygen consumption during submaximal running, (-2.3+/-1.2 vs. -0.3+/-0.7 ml/min/kg, Ptraining phase. Georg Thieme Verlag KG Stuttgart . New York.

The effects of exercise under hypoxia on cognitive function.

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Soichi Ando

Full Text Available Increasing evidence suggests that cognitive function improves during a single bout of moderate exercise. In contrast, exercise under hypoxia may compromise the availability of oxygen. Given that brain function and tissue integrity are dependent on a continuous and sufficient oxygen supply, exercise under hypoxia may impair cognitive function. However, it remains unclear how exercise under hypoxia affects cognitive function. The purpose of this study was to examine the effects of exercise under different levels of hypoxia on cognitive function. Twelve participants performed a cognitive task at rest and during exercise at various fractions of inspired oxygen (FIO2: 0.209, 0.18, and 0.15. Exercise intensity corresponded to 60% of peak oxygen uptake under normoxia. The participants performed a Go/No-Go task requiring executive control. Cognitive function was evaluated using the speed of response (reaction time and response accuracy. We monitored pulse oximetric saturation (SpO2 and cerebral oxygenation to assess oxygen availability. SpO2 and cerebral oxygenation progressively decreased during exercise as the FIO2 level decreased. Nevertheless, the reaction time in the Go-trial significantly decreased during moderate exercise. Hypoxia did not affect reaction time. Neither exercise nor difference in FIO2 level affected response accuracy. An additional experiment indicated that cognitive function was not altered without exercise. These results suggest that the improvement in cognitive function is attributable to exercise, and that hypoxia has no effects on cognitive function at least under the present experimental condition. Exercise-cognition interaction should be further investigated under various environmental and exercise conditions.

Effect of carbon dioxide inhalation on pulmonary hypertension induced by increased blood flow and hypoxia

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I-Chun Chuang

2011-08-01

Full Text Available There is now increasing evidence from the experimental and clinical setting that therapeutic hypercapnia from intentionally inspired carbon dioxide (CO2 or lower tidal volume might be a beneficial adjunct to the strategies of mechanical ventilation in critical illness. Although previous reports indicate that CO2 exerts a beneficial effect in the lungs, the pulmonary vascular response to hypercapnia under various conditions remains to be clarified. The purpose of the present study is to characterize the pulmonary vascular response to CO2 under the different conditions of pulmonary hypertension secondary to increased pulmonary blood flow and secondary to hypoxic pulmonary vasoconstriction. Isolated rat lung (n = 32 was used to study (1 the vasoactive action of 5% CO2 in either N2 (hypoxic-hypercapnia or air (normoxic-hypercapnia at different pulmonary arterial pressure levels induced by graded speed of perfusion flow and (2 the role of nitric oxide (NO in mediating the pulmonary vascular response to hypercapnia, hypoxia, and flow-associated pulmonary hypertension. The results indicated that inhaled CO2 reversed pulmonary hypertension induced by hypoxia but not by flow alteration. Endogenous NO attenuates hypoxic pulmonary vasoconstriction but does not augment the CO2-induced vasodilatation. Acute change in blood flow does not alter the endogenous NO production.

Effects of hypoxia and hypercapnia on geniohyoid contractility and endurance.

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Salmone, R J; Van Lunteren, E

1991-08-01

Sleep apnea and other respiratory diseases produce hypoxemia and hypercapnia, factors that adversely affect skeletal muscle performance. To examine the effects of these chemical alterations on force production by an upper airway dilator muscle, the contractile and endurance characteristics of the geniohyoid muscle were examined in situ during severe hypoxia (arterial PO2 less than 40 Torr), mild hypoxia (PO2 45-65 Torr), and hypercapnia (PCO2 55-80 Torr) and compared with hyperoxic-normocapnic conditions in anesthetized cats. Muscles were studied at optimal length, and contractile force was assessed in response to supramaximal electrical stimulation of the hypoglossal nerve (n = 7 cats) or geniohyoid muscle (n = 2 cats). There were no significant changes in the twitch kinetics or force-frequency curve of the geniohyoid muscle during hypoxia or hypercapnia. However, the endurance of the geniohyoid, as reflected in the fatigue index (ratio of force at 2 min to initial force in response to 40-Hz stimulation at a duty cycle 0.33), was significantly reduced by severe hypoxia but not by hypercapnia or mild hypoxia. In addition, the downward shift in the force-frequency curve after the repetitive stimulation protocol was greater during hypoxia than hyperoxia, especially at higher frequencies. In conclusion, the ability of the geniohyoid muscle to maintain force output during high levels of activation is adversely affected by severe hypoxia but not mild hypoxia or hypercapnia. However, none of these chemical perturbations affected muscle contractility acutely.

Effect of hypoxia on benthic nutrient fluxes in the northwestern Black Sea

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Friedrich, J.

2012-04-01

The western Black Sea shelf has been affected by eutrophication from the 1960s to the mid 1990s. A combination of increased nutrient loads from the major inflowing rivers Danube, Dniester and Dnepr and favourable climate conditions led to high productivity regimes. As a consequence, increased oxygen consumption due to decomposition of organic matter caused recurrent seasonal bottom water hypoxia for more than 20 years. In addition, recycling of nutrients from organic matter settling to the seafloor along with tight benthic-pelagic coupling represents an important internal source for productivity, hence internally supporting eutrophication. From the 1970s to 1990s, the benthic and pelagic systems deteriorated and ecosystem structure and functioning changed. Following the collapse of the centrally planned economies in the eastern European countries during the 1990s, the riverine nutrient input decreased, and the ecosystem, now slowly responding, shows signs of recovery; e.g. by a decrease in hypoxic events. In this study, benthic nutrient flux data from in-situ and ex-situ experiments during the 1990s on the Danube-influenced north-western Black Sea shelf and data from the 2000s, including the EU-FP7 HYPOX experiments, are analysed to reveal the effect of hypoxia on benthic nutrient fluxes. Mann-Whitney statistical tests have been applied to demonstrate the significance of differences in fluxes due to varying oxygen conditions in the water. During the 1990s experiments, bottom water hypoxia was encountered in all locations, while during the 2000s hypoxia has been met only during summer in the Danube Prodelta area and near the Dniester mouth. Indeed, bottom water oxygen in the 1990s has been statistically significantly lower than in the 2000s while benthic oxygen consumption was higher during eutrophication-induced hypoxia. The benthic nutrient fluxes in the 1990s and the 2000s however do not differ significantly. During hypoxia, despite ceasing eutrophication

Edaravone inhibits hypoxia-induced trophoblast-soluble Fms-like tyrosine kinase 1 expression: a possible therapeutic approach to preeclampsia.

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Zhao, Y; Zheng, Y F; Luo, Q Q; Yan, T; Liu, X X; Han, L; Zou, L

2014-07-01

To investigate the effects of edaravone, a potent free radical scavenger used clinically, on hypoxia-induced trophoblast-soluble Fms-like tyrosine kinase 1 (sFlt-1) expression. A trophoblast cell line (HRT-8/SVneo) impaired by cobalt chloride (CoCl2) was used as the cell model under hypoxic conditions. 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide (MTT) was used to measure the viability of cells exposed to CoCl2 and edaravone. The levels of intracellular reactive oxygen species (ROS) were analyzed by flow cytometry. mRNA expression of sFlt-1, vascular endothelial growth factor (VEGF), and placental growth factor (PlGF) in trophoblasts was measured by real-time polymerase chain reaction, and the secretion of sFlt-1, VEGF, and PlGF proteins was analyzed by enzyme-linked immunosorbent assays (ELISAs). A human umbilical vein endothelial cell (HUVEC) tube-formation assay was performed to identify the effects of CoCl2 and edaravone on vascular development. CoCl2 treatment caused the loss of trophoblast viability, the formation of ROS, and sFlt-1 mRNA and protein expression in a dose-dependent manner. Pretreatment with edaravone significantly inhibited hypoxia-induced oxidative stress formation and sFlt-1 expression in trophoblasts. Neither PlGF nor VEGF mRNA or protein expression was increased by CoCl2. In the in vitro tube formation assay, edaravone showed a protective role in vascular development under hypoxic conditions. This study demonstrated that hypoxia leading to increased sFlt-1 release in trophoblasts may contribute to the placental vascular formation abnormalities observed in preeclampsia and suggested that the free radical scavenger edaravone could be a candidate for the effective treatment of preeclampsia. Copyright © 2014 Elsevier Ltd. All rights reserved.

Targeting demyelination and virtual hypoxia with high-dose biotin as a treatment for progressive multiple sclerosis.

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Sedel, Frédéric; Bernard, Delphine; Mock, Donald M; Tourbah, Ayman

2016-11-01

Progressive multiple sclerosis (MS) is a severely disabling neurological condition, and an effective treatment is urgently needed. Recently, high-dose biotin has emerged as a promising therapy for affected individuals. Initial clinical data have shown that daily doses of biotin of up to 300 mg can improve objective measures of MS-related disability. In this article, we review the biology of biotin and explore the properties of this ubiquitous coenzyme that may explain the encouraging responses seen in patients with progressive MS. The gradual worsening of neurological disability in patients with progressive MS is caused by progressive axonal loss or damage. The triggers for axonal loss in MS likely include both inflammatory demyelination of the myelin sheath and primary neurodegeneration caused by a state of virtual hypoxia within the neuron. Accordingly, targeting both these pathological processes could be effective in the treatment of progressive MS. Biotin is an essential co-factor for five carboxylases involved in fatty acid synthesis and energy production. We hypothesize that high-dose biotin is exerting a therapeutic effect in patients with progressive MS through two different and complementary mechanisms: by promoting axonal remyelination by enhancing myelin production and by reducing axonal hypoxia through enhanced energy production. This article is part of the Special Issue entitled 'Oligodendrocytes in Health and Disease'. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Hypoxia-targeted suicidal gene therapy system enhances antitumor effects of radiotherapy

International Nuclear Information System (INIS)

Liu Junye; Guo Yao; Guo Guozhen

2006-01-01

Objective: To explore the effects of hypoxia-targeted suicidal gene therapy system combined with radiotherapy on pancreatic cancer. Methods: The recombinant adenovirus Ad-5HRE/hCMVmp-BCD was constructed by DNA recombinant technique. Western blot was used to detect hypoxia-induced expression of bacterial cytosine deaminase (BCD). Cell growth inhibition assay was used to determine the sensitivity of human pancreatic cancer cells MIA-PACA2 to 5-fluorocytosine (5-FC). Tumor xenograft growth delay assays was used to evaluate the effects of Ad-5HRE/hCMVmp-BCD/5-FC combined with radiotherapy on pancreatic cancer. Results: Western blot analysis demonstrated that hypoxia-induced BCD protein expression was achieved in MIA-PACA2 cells infected with Ad-5HRE/hCMVmp-BCD. With hypoxia treatment, the sensitivity of MIA-PACA2 cells infected with Ad-5HRE/hCMVmp-BCD to 5-FC significantly increased. Administration of either Ad-5HRE/hCMVmp-BCD/5-FC or radiotherapy could inhibit the growth of MIA-PACA2 xenografts in nude mice. Moreover, combination of Ad-5HRE/hCMVmp-BCD/5-FC could significantly enhance suppressing effects of radiotherapy on MIA-PACA2 xenografts. Conclusion: Hypoxia-targeted suicidal gene therapy system Ad-5HRE/hCMVmp-BCD/5-FC could enhance antitumor effects of radiotherapy on pancreatic cancer and can be used as a powerful adjunct to conventional radiotherapy. (authors)

The Clinical Importance of Assessing Tumor Hypoxia: Relationship of Tumor Hypoxia to Prognosis and Therapeutic Opportunities

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Walsh, Joseph C.; Lebedev, Artem; Aten, Edward; Madsen, Kathleen; Marciano, Liane

2014-01-01

I. Introduction II. The Clinical Importance of Tumor Hypoxia A. Pathophysiology of hypoxia B. Hypoxia's negative impact on the effectiveness of curative treatment 1. Hypoxic tumors accumulate and propagate cancer stem cells 2. Hypoxia reduces the effectiveness of radiotherapy 3. Hypoxia increases metastasis risk and reduces the effectiveness of surgery 4. Hypoxic tumors are resistant to the effects of chemotherapy and chemoradiation C. Hypoxia is prognostic for poor patient outcomes III. Diagnosis of Tumor Hypoxia A. Direct methods 1. Oxygen electrode—direct pO2 measurement most used in cancer research 2. Phosphorescence quenching—alternative direct pO2 measurement 3. Electron paramagnetic resonance 4. 19F-magnetic resonance spectroscopy 5. Overhauser-enhanced MRI B. Endogenous markers of hypoxia 1. Hypoxia-inducible factor-1α 2. Carbonic anhydrase IX 3. Glucose transporter 1 4. Osteopontin 5. A combined IHC panel of protein markers for hypoxia 6. Comet assay C. Physiologic methods 1. Near-infrared spectroscopy/tomography—widely used for pulse oximetry 2. Photoacoustic tomography 3. Contrast-enhanced color duplex sonography 4. MRI-based measurements 5. Blood oxygen level-dependent MRI 6. Pimonidazole 7. EF5 (pentafluorinated etanidazole) 8. Hypoxia PET imaging—physiologic hypoxia measurement providing tomographic information a. 18F-fluoromisonidazole b. 18F-fluoroazomycinarabinofuranoside c. 18F-EF5 (pentafluorinated etanidazole) d. 18F-flortanidazole e. Copper (II) (diacetyl-bis (N4-methylthiosemicarbazone)) f. 18F-FDG imaging of hypoxia IV. Modifying Hypoxia to Improve Therapeutic Outcomes A. Use of hypoxia information in radiation therapy planning B. Use of hypoxia assessment for selection of patients responsive to nimorazole C. Use of hypoxia assessment for selection of patients responsive to tirapazamine D. Use of hypoxia assessment for selection of patients

Salivary Gland Derived BDNF Overexpression in Mice Exerts an Anxiolytic Effect

OpenAIRE

Saruta, Juri; To, Masahiro; Sugimoto, Masahiro; Yamamoto, Yuko; Shimizu, Tomoko; Nakagawa, Yusuke; Inoue, Hiroko; Saito, Ichiro; Tsukinoki, Keiichi

2017-01-01

Brain-derived neurotrophic factor (BDNF) is abundant in the hippocampus and plays critical roles in memory and synapse formation, as well as exerting antidepressant-like effects in psychiatric disorders. We previously reported that BDNF is expressed in salivary glands and affects blood BDNF content. However, the function of salivary BDNF remains unclear. The aim of this study was to generate transgenic mice overexpressing BDNF in the salivary glands. Hence, we used the Lama construct (hemaggl...

Effect of low-frequency low-intensity ultrasound with microbubbles on prostate cancer hypoxia.

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Hou, Rui; Xu, Yanjun; Lu, Qijie; Zhang, Yang; Hu, Bing

2017-10-01

Angiogenesis plays an important role in tumor growth, invasiveness, and metastasis. It is well established that prostate cancer is exposed to fluctuating oxygen tensions and both acute and chronic hypoxia exist, and these conditions can upregulate angiogenesis-associated proteins such as hypoxia-inducible factor 1 alpha and vascular endothelial growth factor A. Low-frequency low-intensity ultrasound with microbubbles can induce obvious microvessel damage in tumors, cause cell necrosis or apoptosis. However, there is no information about whether the blocking blood effect of low-frequency low-intensity ultrasound with microbubbles has an influence on hypoxia environment of prostate cancer. Therefore, we investigated the impact of different low-frequency low-intensity ultrasound with microbubbles radiation times on prostate tumors, observed the change in the hypoxia-inducible factor 1 alpha and vascular endothelial growth factor A protein levels, as well as cell proliferation, apoptosis, and tumor volume. The results indicated that as the radiation was repeated four times on each treatment day, the effects of interruption were durable, the cell proliferation was inhibited, and apoptosis was promoted, and the hypoxia-inducible factor 1 alpha and vascular endothelial growth factor A expression levels were lower in the treatment group than in the control group. When the radiation was carried out once per treatment day, the hypoxia response was stimulated, the hypoxia-inducible factor 1 alpha and vascular endothelial growth factor A expression levels were higher compared with the control group, and cell proliferation was promoted. In addition, the tumor volume increased obviously in the hypoxia-stimulated group, whereas tumors grew slowly in the hypoxia-suppressed group. The results of this work demonstrated that under the same conditions, different radiation times of low-frequency low-intensity ultrasound with microbubbles affect the hypoxia response differently, and the

EGb 761 Protects Cardiac Microvascular Endothelial Cells against Hypoxia/Reoxygenation Injury and Exerts Inhibitory Effect on the ATM Pathway.

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Zhang, Chao; Wang, Deng-Feng; Zhang, Zhuang; Han, Dong; Yang, Kan

2017-03-28

Ginkgo bilob a extract (EGb 761) has been widely used clinically to reduce myocardial ischemia reperfusion injury (MIRI). Microvascular endothelial cells (MVECs) may be a proper cellular model in vitro for the effect and mechanism study against MIRI. However, the protective effect of EGb 761 on MVECs resisting hypoxia/reoxygenation (H/R) injury is little reported. In this study, H/R-injured MVECs were treated with EGb 761, and then the cell viability, apoptosis, ROS production, SOD activity, caspase-3 activity, and protein level of ATM, γ-H2AX, p53, and Bax were measured. ATM siRNA was transfected to study the changes of protein in the ATM pathway. EGb 761 presented protective effect on H/R-injured MVECs, with decreasing cell death, apoptosis, and ROS, and elevated SOD activity. Next, EGb 761 could inhibit H/R-induced ATM, γ-H2AX, p53, and Bax in a dose-dependent manner. Moreover, ATM siRNA also could inhibit H/R-induced ATM, γ-H2AX, p53, and Bax. Overall, these findings verify that EGb 761 protects cardiac MVECs from H/R injury, and for the first time, illustrate the influence on the ATM pathway and apoptosis by EGb 761 via dampening ROS.

The effect of hypobaric hypoxia on multichannel EEG signal complexity.

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Papadelis, Christos; Kourtidou-Papadeli, Chrysoula; Bamidis, Panagiotis D; Maglaveras, Nikos; Pappas, Konstantinos

2007-01-01

The objective of this study was the development and evaluation of nonlinear electroencephalography parameters which assess hypoxia-induced EEG alterations, and describe the temporal characteristics of different hypoxic levels' residual effect upon the brain electrical activity. Multichannel EEG, pO2, pCO2, ECG, and respiration measurements were recorded from 10 subjects exposed to three experimental conditions (100% oxygen, hypoxia, recovery) at three-levels of reduced barometric pressure. The mean spectral power of EEG under each session and altitude were estimated for the standard bands. Approximate Entropy (ApEn) of EEG segments was calculated, and the ApEn's time-courses were smoothed by a moving average filter. On the smoothed diagrams, parameters were defined. A significant increase in total power and power of theta and alpha bands was observed during hypoxia. Visual interpretation of ApEn time-courses revealed a characteristic pattern (decreasing during hypoxia and recovering after oxygen re-administration). The introduced qEEG parameters S1 and K1 distinguished successfully the three hypoxic conditions. The introduced parameters based on ApEn time-courses are assessing reliably and effectively the different hypoxic levels. ApEn decrease may be explained by neurons' functional isolation due to hypoxia since decreased complexity corresponds to greater autonomy of components, although this interpretation should be further supported by electrocorticographic animal studies. The introduced qEEG parameters seem to be appropriate for assessing the hypoxia-related neurophysiological state of patients in the hyperbaric chambers in the treatment of decompression sickness, carbon dioxide poisoning, and mountaineering.

PACAP and VIP inhibit the invasiveness of glioblastoma cells exposed to hypoxia through the regulation of HIFs and EGFR expression

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Grazia eMaugeri

2016-05-01

Full Text Available Pituitary adenylate cyclase-activating polypeptide (PACAP and vasoactive intestinal peptide (VIP through the binding of vasoactive intestinal peptide receptors (VIPRs, perform a wide variety of effects in human cancers, including glioblastoma multiforme (GBM. This tumor is characterized by extensive areas of hypoxia, which triggers the expression of hypoxia-inducible factors (HIFs. HIFs not only mediate angiogenesis but also tumor cell migration and invasion. Furthermore, HIFs activation is linked to epidermal growth factor receptor (EGFR overexpression. Previous studies have shown that VIP interferes with the invasive nature of gliomas by regulating cell migration. However, the role of VIP family members in GBM infiltration under low oxygen tension has not been clarified yet. Therefore, in the present study we have investigated, for the first time, the molecular mechanisms involved in the anti-invasive effect of PACAP or VIP in U87MG glioblastoma cells exposed to hypoxia induced by treatment with desferrioxamine (DFX. The results suggest that either PACAP or VIP exert an anti-infiltrative effect under low oxygen tension by modulating HIFs and EGFR expression, key elements involved in cell migration and angiogenesis. These peptides act through the inhibition of PI3K/Akt and MAPK/ERK signaling pathways, which are known to have a crucial role in HIFs regulation. In conclusion, the modulation of hypoxic event and the anti-invasive effect exerted by some VIP family members might open new insights in the therapeutic approach to GBM.

Effects of natural and human-induced hypoxia on coastal benthos

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Levin, L. A.; Ekau, W.; Gooday, A. J.; Jorissen, F.; Middelburg, J. J.; Naqvi, S. W. A.; Neira, C.; Rabalais, N. N.; Zhang, J.

2009-10-01

Coastal hypoxia (defined here as branchial structures, predominate. Large taxa are more sensitive than small taxa to hypoxia. Crustaceans and echinoderms are typically more sensitive to hypoxia, with lower oxygen thresholds, than annelids, sipunculans, molluscs and cnidarians. Mobile fish and shellfish will migrate away from low-oxygen areas. Within a species, early life stages may be more subject to oxygen stress than older life stages. Hypoxia alters both the structure and function of benthic communities, but effects may differ with regional hypoxia history. Human-caused hypoxia is generally linked to eutrophication, and occurs adjacent to watersheds with large populations or agricultural activities. Many occurrences are seasonal, within estuaries, fjords or enclosed seas of the North Atlantic and the NW Pacific Oceans. Benthic faunal responses, elicited at oxygen levels below 2 ml L-1, typically involve avoidance or mortality of large species and elevated abundances of enrichment opportunists, sometimes prior to population crashes. Areas of low oxygen persist seasonally or continuously beneath upwelling regions, associated with the upper parts of oxygen minimum zones (SE Pacific, W Africa, N Indian Ocean). These have a distribution largely distinct from eutrophic areas and support a resident fauna that is adapted to survive and reproduce at oxygen concentrations <0.5 ml L-1. Under both natural and eutrophication-caused hypoxia there is loss of diversity, through attrition of intolerant species and elevated dominance, as well as reductions in body size. These shifts in species composition and diversity yield altered trophic structure, energy flow pathways, and corresponding ecosystem services such as production, organic matter cycling and organic C burial. Increasingly the influences of nature and humans interact to generate or exacerbate hypoxia. A warmer ocean is more stratified, holds less oxygen, and may experience greater advection of oxygen-poor source

Hypoxia is no hype: Perspectives across Phylogeny, Stem Cell differentiation & Geochemistry

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Editorial

2015-05-01

Full Text Available Influence of atmospheric gases in the eco systems on the habituating living organisms, an area of focus of the geochemists and astro-biologists, have been known for eons. Though the modus operandi of the implication varies between unicellular and multi-system centered organisms up in the ladder of phylogeny, their significance though known, the intricacies to the fullest extent have not been thoroughly understood to enable us to exploit them to our best in bringing solutions to address various problems. In this issue, Ito et al have reported a simple hypoxic culture system [1] with a built-in deoxidizing agent capable of promoting stem cell proliferation, repressing cell senescence without aggravating the stem cell viability. Studying hypoxia gains significance because oxygen exerts a profound influence on life on earth. Oxygen requirements differ across cells, tissues, organisms and phylogeny. The primitive life forms on earth which formed nearly four billion years ago were able to thrive without oxygen, which became a life influencing factor only two billion years ago during when its levels in the atmosphere were actually toxic to the organisms which evolved ways to detoxify them and over time these organisms became dependant on oxygen [2]. Among cellular processes, the low energy supply during a hypoxic metabolic state allows only DNA replication or basic cell reproduction functions which are essential for a cell’s survival suppressing the specialised functions like differentiation [2]. Thus, stemness is preserved more efficiently under hypoxia and it is suggested that in vitro stem cells should ideally be maintained at oxygen concentrations lower than 1% and approaching zero which recapitulate the atmospheric oxygen concentrations that existed on earth 2-3 billion years ago, as stem cells are believed to reflect an early evolutionary stage compared to other cells [2]. Hypoxia has shown to promote stemness in various kinds of stem cells

Multi-Vitamin B Supplementation Reverses Hypoxia-Induced Tau Hyperphosphorylation and Improves Memory Function in Adult Mice.

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Yu, Lixia; Chen, Yuan; Wang, Weiguang; Xiao, Zhonghai; Hong, Yan

2016-08-04

Hypobaric hypoxia (HH) leads to reduced oxygen delivery to brain. It could trigger cognitive dysfunction and increase the risk of dementia including Alzheimer's disease (AD). The present study was undertaken in order to examine whether B vitamins (B6, B12, folate, and choline) could exert protective effects on hypoxia-induced memory deficit and AD related molecular events in mice. Adult male Kunming mice were assigned to five groups: normoxic control, hypoxic model (HH), hypoxia+vitamin B6/B12/folate (HB), hypoxia+choline (HC), hypoxia+vitamin B6/B12/folate+choline (HBC). Mice in the hypoxia, HB, HC, and HBC groups were exposed to hypobaric hypoxia for 8 h/day for 28 days in a decompression chamber mimicking 5500 meters of high altitude. Spatial and passive memories were assessed by radial arm and step-through passive test, respectively. Levels of tau and glycogen synthase kinase (GSK)-3β phosphorylation were detected by western blot. Homocysteine (Hcy) concentrations were determined using enzymatic cycling assay. Mice in the HH group exhibited significant spatial working and passive memory impairment, increased tau phosphorylation at Thr181, Ser262, Ser202/Thr205, and Ser396 in the cortex and hippocampus, and elevated Hcy levels compared with controls. Concomitantly, the levels of Ser9-phosphorylated GSK-3β were significantly decreased in brain after hypoxic treatment. Supplementations of vitamin B6/B12/folate+choline could significantly ameliorate the hypoxia-induced memory deficits, observably decreased Hcy concentrations in serum, and markedly attenuated tau hyperphosphorylation at multiple AD-related sites through upregulating inhibitory Ser9-phosphorylated GSK-3β. Our finding give further insight into combined neuroprotective effects of vitamin B6, B12, folate, and choline on brain against hypoxia.

Mechanical and hypoxia stress can cause chondrocytes apoptosis through over-activation of endoplasmic reticulum stress.

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Huang, Ziwei; Zhou, Min; Wang, Qian; Zhu, Mengjiao; Chen, Sheng; Li, Huang

2017-12-01

To examine the role of mechanical force and hypoxia on chondrocytes apoptosis and osteoarthritis (OA)-liked pathological change on mandibular cartilage through over-activation of endoplasmic reticulum stress (ERS). We used two in vitro models to examine the effect of mechanical force and hypoxia on chondrocytes apoptosis separately. The mandibular condylar chondrocytes were obtained from three-week-old male Sprague-Dawley rats. Flexcell 5000T apparatus was used to produce mechanical forces (12%, 0.5Hz, 24h vs 20%, 0.5Hz, 24h) on chondrocytes. For hypoxia experiment, the concentration of O 2 was down regulated to 5% or 1%. Cell apoptosis rates were quantified by annexin V and propidium iodide (PI) double staining and FACS analysis. Quantitative real-time PCR and western blot were performed to evaluate the activation of ERS and cellular hypoxia. Then we used a mechanical stress loading rat model to verify the involvement of ERS in OA-liked mandibular cartilage pathological change. Histological changes in mandibular condylar cartilage were assessed via hematoxylin & eosin (HE) staining. Immunohistochemistry of GRP78, GRP94, HIF-1α, and HIF-2α were performed to evaluate activation of the ERS and existence of hypoxia. Apoptotic cells were detected by the TUNEL method. Tunicamycin, 20% mechanical forces and hypoxia (1% O 2 ) all significantly increased chondrocytes apoptosis rates and expression of ERS markers (GRP78, GRP94 and Caspase 12). However, 12% mechanical forces can only increase the apoptotic sensitivity of chondrocytes. Mechanical stress resulted in OA-liked pathological change on rat mandibular condylar cartilage which included thinning cartilage and bone erosion. The number of apoptotic cells increased. ERS and hypoxia markers expressions were also enhanced. Salubrinal, an ERS inhibitor, can reverse these effects in vitro and in vivo through the down-regulation of ERS markers and hypoxia markers. We confirmed that mechanical stress and local hypoxia both

Effect of acadesine on breast cancer cells under hypoxia

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A. M. Shcherbakov

2017-01-01

Full Text Available The riboside derivative acadesine (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside is currently being tested in clinical trials as a promising anti-tumor drug. Intracellular target of acadesine is adenosine monophosphate-activated protein kinase (АМРК, an important regulatory molecule of energy metabolism. It is expected that acadesine would be active in tumors under hypoxia conditions. In normoxia (cells incubated in 21 % oxygen, acadesine inhibited proliferation and induced cell death of breast adenocarcinoma, including the triple negative breast cancer line. When oxygen partial pressure was decreased to 1 % (experimental hypoxia, acadesine inhibited activation of reporter construct responsive to HIF-1α (hypoxia inducible factor 1 alpha transcription factor. This effect was observed for acadesine in concentrations close to cytotoxic. Acadesine retained cytotoxicity under hypoxia and decreased the survival of the MDA-MB-231 cell line when used in combination with cisplatin. These results considerably widen acadesine’s field of application and allow to assume its efficacy in chemotherapy combination regimens for breast cancer, including the tumors with low oxygenation.

Impact of miR-208 and its Target Gene Nemo-Like Kinase on the Protective Effect of Ginsenoside Rb1 in Hypoxia/Ischemia Injuried Cardiomyocytes

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Xu Yan

2016-09-01

Full Text Available Background/Aims: Ginsenoside Rb1 (GS-Rb1 is one of the most important active pharmacological extracts of the Traditional Chinese Medicine ginseng, with extensive evidence of its cardioprotective properties. Mir-208 has been shown to act as a biomarker of acute myocardial infarction in vivo studies including man. However the impact of miR-208 on the protective effect of GS-Rb1 in hypoxia/ischemia injured cardiomyocytes remains unclear. The current study aims to investigate the target gene of miR-208 and the impact on the protective effect of GS-Rb1 in hypoxia/ischemia (H/I injuried cardiomyocytes. Materials and Methods: Primary cultures of neonatal rat cardiomyocytes (NRCMs was subjected to the H/I conditions with or without GS-Rb1. Cell viability was calculated by MTT assay and confirmed by flow cytometry analysis. Mir-208 was then detected by qRT-PCR. Luciferase reporter assay was carried out to detect the target gene of Mir-208. Then the NRCMs were transfected with miR-208 mimics and inhibitors to evaluate the impact on cardioprotective properties of Rb1. Results: The miR-208 expression level was clearly upregulated in the H/I treated NRCMs accompanied by the percentage of the apoptotic cells which could be reversed by GS-Rb1 pretreatment. The nemo-like kinase (NLK mRNA and protein expression levels were decreased in H/I group measured by RT-PCR and western blotting. Luciferase activity assay was then carried out to identify that NLK may be a direct target of mir-208. MTT assay showed that miR-208 inhibitor slightly decreased the protective effect of Rb1 on the H/I impaired NRCMs. However, results showed no statistical difference. Conclusions: These findings proved that NLK was a direct target of mir-208 and miR-208 act indirectly during Rb1 protecting H/I impaired NRCMs and further researches were needed to explore the relationship that microRNAs and other signal pathways in the protective effect of GS-Rb1 on the hypoxia/ischemia injuries in

Hypoxia Potentiates Anabolic Effects of Exogenous Hyaluronic Acid in Rat Articular Cartilage.

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Ichimaru, Shohei; Nakagawa, Shuji; Arai, Yuji; Kishida, Tsunao; Shin-Ya, Masaharu; Honjo, Kuniaki; Tsuchida, Shinji; Inoue, Hiroaki; Fujiwara, Hiroyoshi; Shimomura, Seiji; Mazda, Osam; Kubo, Toshikazu

2016-06-25

Hyaluronic acid (HA) is used clinically to treat osteoarthritis (OA), but its pharmacological effects under hypoxic conditions remain unclear. Articular chondrocytes in patients with OA are exposed to a hypoxic environment. This study investigated whether hypoxia could potentiate the anabolic effects of exogenous HA in rat articular cartilage and whether these mechanisms involved HA receptors. HA under hypoxic conditions significantly enhanced the expression of extracellular matrix genes and proteins in explant culture, as shown by real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and dimethylmethylene blue (DMMB) assays. Staining with Safranin-O and immunohistochemical staining with antibody to type II collagen were also enhanced in pellet culture. The expression of CD44 was increased by hypoxia and significantly suppressed by transfection with siRNAs targeting hypoxia-inducible factor 1 alpha (siHIF-1α). These findings indicate that hypoxia potentiates the anabolic effects of exogenous HA by a mechanism in which HIF-1α positively regulates the expression of CD44, enhancing the binding affinity for exogenous HA. The anabolic effects of exogenous HA may increase as OA progresses.

Hypoxia and hypoxia mimetics decrease aquaporin 5 (AQP5 expression through both hypoxia inducible factor-1α and proteasome-mediated pathways.

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Jitesh D Kawedia

Full Text Available The alveolar epithelium plays a central role in gas exchange and fluid transport, and is therefore critical for normal lung function. Since the bulk of water flux across this epithelium depends on the membrane water channel Aquaporin 5 (AQP5, we asked whether hypoxia had any effect on AQP5 expression. We show that hypoxia causes a significant (70% decrease in AQP5 expression in the lungs of mice exposed to hypoxia. Hypoxia and the hypoxia mimetic, cobalt, also caused similar decreases in AQP5 mRNA and protein expression in the mouse lung epithelial cell line MLE-12. The action of hypoxia and cobalt on AQP5 transcription was demonstrated by directly quantifying heternonuclear RNA by real-time PCR. Dominant negative mutants of Hypoxia Inducible Factor (HIF-1α and HIF-1α siRNA blocked the action of cobalt, showing that HIF-1α is a key component in this mechanism. The proteasome inhibitors, lactacystin or proteasome inhibitor-III completely abolished the effect of hypoxia and cobalt both at the protein and mRNA level indicating that the proteasome pathway is probably involved not only for the stability of HIF-1α protein, but for the stability of unidentified transcription factors that regulate AQP5 transcription. These studies reveal a potentially important physiological mechanism linking hypoxic stress and membrane water channels.

Hypoxia and Hypoxia Mimetics Decrease Aquaporin 5 (AQP5) Expression through Both Hypoxia Inducible Factor-1α and Proteasome-Mediated Pathways

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Kawedia, Jitesh D.; Yang, Fan; Sartor, Maureen A.; Gozal, David; Czyzyk-Krzeska, Maria; Menon, Anil G.

2013-01-01

The alveolar epithelium plays a central role in gas exchange and fluid transport, and is therefore critical for normal lung function. Since the bulk of water flux across this epithelium depends on the membrane water channel Aquaporin 5 (AQP5), we asked whether hypoxia had any effect on AQP5 expression. We show that hypoxia causes a significant (70%) decrease in AQP5 expression in the lungs of mice exposed to hypoxia. Hypoxia and the hypoxia mimetic, cobalt, also caused similar decreases in AQP5 mRNA and protein expression in the mouse lung epithelial cell line MLE-12. The action of hypoxia and cobalt on AQP5 transcription was demonstrated by directly quantifying heternonuclear RNA by real-time PCR. Dominant negative mutants of Hypoxia Inducible Factor (HIF-1α) and HIF-1α siRNA blocked the action of cobalt, showing that HIF-1α is a key component in this mechanism. The proteasome inhibitors, lactacystin or proteasome inhibitor-III completely abolished the effect of hypoxia and cobalt both at the protein and mRNA level indicating that the proteasome pathway is probably involved not only for the stability of HIF-1α protein, but for the stability of unidentified transcription factors that regulate AQP5 transcription. These studies reveal a potentially important physiological mechanism linking hypoxic stress and membrane water channels. PMID:23469202

An effective tumor-targeting strategy utilizing hypoxia-sensitive siRNA delivery system for improved anti-tumor outcome.

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Kang, Lin; Fan, Bo; Sun, Ping; Huang, Wei; Jin, Mingji; Wang, Qiming; Gao, Zhonggao

2016-10-15

Hypoxia is a feature of most solid tumors, targeting hypoxia is considered as the best validated yet not extensively exploited strategy in cancer therapy. Here, we reported a novel tumor-targeting strategy using a hypoxia-sensitive siRNA delivery system. In the study, 2-nitroimidazole (NI), a hydrophobic component that can be converted to hydrophilic 2-aminoimidazole (AI) through bioreduction under hypoxic conditions, was conjugated to the alkylated polyethyleneimine (bPEI1.8k-C6) to form amphiphilic bPEI1.8k-C6-NI polycations. bPEI1.8k-C6-NI could self-assemble into micelle-like aggregations in aqueous, which contributed to the improved stability of the bPEI1.8k-C6-NI/siRNA polyplexes, resulted in increased cellular uptake. After being transported into the hypoxic tumor cells, the selective nitro-to-amino reduction would cause structural change and elicit a relatively loose structure to facilitate the siRNA dissociation in the cytoplasm, for enhanced gene silencing efficiency ultimately. Therefore, the conflict between the extracellular stability and the intracellular siRNA release ability of the polyplexes was solved by introducing the hypoxia-responsive unit. Consequently, the survivin-targeted siRNA loaded polyplexes shown remarkable anti-tumor effect not only in hypoxic cells, but also in tumor spheroids and tumor-bearing mice, indicating that the hypoxia-sensitive siRNA delivery system had great potential for tumor-targeted therapy. Hypoxia is one of the most remarkable features of most solid tumors, and targeting hypoxia is considered as the best validated strategy in cancer therapy. However, in the past decades, there were few reports about using this strategy in the drug delivery system, especially in siRNA delivery system. Therefore, we constructed a hypoxia-sensitive siRNA delivery system utilizing a hypoxia-responsive unit, 2-nitroimidazole, by which the unavoidable conflict between improved extracellular stability and promoted intracellular si

Acute effects of head-down tilt and hypoxia on modulators of fluid homeostasis

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Whitson, P. A.; Cintron, N. M.; Pietrzyk, R. A.; Scotto, P.; Loeppky, J. A.

1994-01-01

In an effort to understand the interaction between acute postural fluid shifts and hypoxia on hormonal regulation of fluid homeostasis, the authors measured the responses to head-down tilt with and without acute exposure to normobaric hypoxia. Plasma atrial natriuretic peptide (ANP), cyclic guanosine monophosphate (cGMP), cyclic adenosine monophosphate (cAMP), plasma aldosterone (ALD), and plasma renin activity (PRA) were measured in six healthy male volunteers who were exposed to a head-down tilt protocol during normoxia and hypoxia. The tilt protocol consisted of a 17 degrees head-up phase (30 minutes), a 28 degrees head-down phase (1 hour), and a 17 degrees head-up recovery period (2 hours, with the last hour normoxic in both experiments). Altitude equivalent to 14,828 ft was simulated by having the subjects breathe an inspired gas mixture with 13.9% oxygen. The results indicate that the postural fluid redistribution associated with a 60-minute head-down tilt induces the release of ANP and cGMP during both hypoxia and normoxia. Hypoxia increased cGMP, cAMP, ALD, and PRA throughout the protocol and significantly potentiated the increase in cGMP during head-down tilt. Hypoxia had no overall effect on the release of ANP, but appeared to attenuate the increase with head-down tilt. This study describes the acute effects of hypoxia on the endocrine response during fluid redistribution and suggests that the magnitude, but not the direction, of these changes with posture is affected by hypoxia.

The interactive effect of cooling and hypoxia on forearm fatigue development.

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Lloyd, Alex; Hodder, Simon; Havenith, George

2015-09-01

To examine the effect of separate and combined exposure to hypoxia [normoxia (FIO2 = 0.21) vs. moderate altitude (FIO2 = 0.13)] and temperature [thermoneutral (22 °C) vs. cold (5 °C)] on muscle fatigue development in the forearm, after repeated low-resistance contractions. Eight males were exposed for 70 min to four separate conditions in a balanced order. Conditions were normoxic-thermoneutral (N), hypoxic-thermoneutral, normoxic-cold and hypoxic-cold. After 15-min seated rest, participants carried out intermittent dynamic forearm exercise at 15 % maximal isometric voluntary contraction (MVC) for eight consecutive, 5-min work bouts. Each bout was separated by 110 s rest during which MVC force was collected. When exposed to hypoxia and cold independently, the exercise protocol decreased MVC force of the finger flexors by 8.1 and 13.9 %, respectively, compared to thermoneutral normoxia. When hypoxia and cold were combined, the decrease in MVC force was 21.4 % more than thermoneutral normoxia, reflecting an additive effect and no interaction. EMG relative to force produced during MVC, increased by 2 and 1.2 μV per kg (36 and 23 % of N) for cold and hypoxia, respectively. When the stressors were combined the effect was additive, increasing to 3.1 μV per kg (56 % of N). When compared to exercise in thermoneutral normoxic conditions, both cold and hypoxia significantly reduce brief MVC force output. This effect appears to be of mechanical origin, not a failure in muscle fibre recruitment per se. Additionally, the reduction in force is greater when the stressors are combined, showing an additive effect.

The Wnt/β-catenin signaling/Id2 cascade mediates the effects of hypoxia on the hierarchy of colorectal-cancer stem cells.

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Dong, Hye-Jin; Jang, Gyu-Beom; Lee, Hwa-Yong; Park, Se-Ra; Kim, Ji-Young; Nam, Jeong-Seok; Hong, In-Sun

2016-03-11

Hypoxia, a feature common to most solid tumors, is known to regulate many aspects of tumorigenesis. Recently, it was suggested that hypoxia increased the size of the cancer stem-cell (CSC) subpopulations and promoted the acquisition of a CSC-like phenotype. However, candidate hypoxia-regulated mediators specifically relevant to the stemness-related functions of colorectal CSCs have not been examined in detail. In the present study, we showed that hypoxia specifically promoted the self-renewal potential of CSCs. Through various in vitro studies, we found that hypoxia-induced Wnt/β-catenin signaling increased the occurrence of CSC-like phenotypes and the level of Id2 expression in colorectal-cancer cells. Importantly, the levels of hypoxia-induced CSC-sphere formation and Id2 expression were successfully attenuated by treatment with a Wnt/β-catenin-signaling inhibitor. We further demonstrated, for the first time, that the degree of hypoxia-induced CSC-sphere formation (CD44(+) subpopulation) in vitro and of tumor metastasis/dissemination in vivo were markedly suppressed by knocking down Id2 expression. Taken together, these data suggested that Wnt/β-catenin signaling mediated the hypoxia-induced self-renewal potential of colorectal-cancer CSCs through reactivating Id2 expression.

Cellular effects of the microtubule-targeting agent peloruside A in hypoxia-conditioned colorectal carcinoma cells.

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Řehulka, Jiří; Annadurai, Narendran; Frydrych, Ivo; Znojek, Pawel; Džubák, Petr; Northcote, Peter; Miller, John H; Hajdúch, Marián; Das, Viswanath

2017-07-01

Hypoxia is a prominent feature of solid tumors, dramatically remodeling microtubule structures and cellular pathways and contributing to paclitaxel resistance. Peloruside A (PLA), a microtubule-targeting agent, has shown promising anti-tumor effects in preclinical studies. Although it has a similar mode of action to paclitaxel, it binds to a distinct site on β-tubulin that differs from the classical taxane site. In this study, we examined the unexplored effects of PLA in hypoxia-conditioned colorectal HCT116 cancer cells. Cytotoxicity of PLA was determined by cell proliferation assay. The effects of a pre-exposure to hypoxia on PLA-induced cell cycle alterations and apoptosis were examined by flow cytometry, time-lapse imaging, and western blot analysis of selected markers. The hypoxia effect on stabilization of microtubules by PLA was monitored by an intracellular tubulin polymerization assay. Our findings show that the cytotoxicity of PLA is not altered in hypoxia-conditioned cells compared to paclitaxel and vincristine. Furthermore, hypoxia does not alter PLA-induced microtubule stabilization nor the multinucleation of cells. PLA causes cyclin B1 and G2/M accumulation followed by apoptosis. The cellular and molecular effects of PLA have been determined in normoxic conditions, but there are no reports of PLA effects in hypoxic cells. Our findings reveal that hypoxia preconditioning does not alter the sensitivity of HCT116 to PLA. These data report on the cellular and molecular effects of PLA in hypoxia-conditioned cells for the first time, and will encourage further exploration of PLA as a promising anti-tumor agent. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of hypoxia on epididymal sperm parameters and protective role of ibuprofen and melatonin

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Álvaro Vargas

2011-01-01

Full Text Available Hypobaric hypoxia is of interest due to an increase of human populations working at high altitude. Testicular damage is related to the physiological response (neoangiogenesis to increased intrascrotal blood flow as temperature rises. Hypoxia is a stress factor with overproduction of reactive oxygen species (ROS. The effect of hypoxia in mice reproductive parameters is analyzed. Animals were exposed to simulated hypoxia of 4,200 meters above sea level (m.a.s.l. in a chamber for 33.2 days, both to continuous (HH or intermittent hypoxia (HI with an intermittency period of 4 days hypoxia /4 days normoxia (500 m.a.s.l.. The anti-inflammatory drug Ibuprofen was administered to a group of mice to control vasodilation and increased blood flow. Melatonin was administered to another group of mice as a potent ROS scavenger. Animals in both HH and HI exposure were compared to normoxic non-treated controls. There was a hematological response in hypoxia, with an increase in hematocrit and reticulocytosis. There was also increased teratozoospermia. This damage was more pronounced in HH than HI, suggesting that alternating normoxic periods permits compensation for the effects of hypoxia. In both hypoxia systems, the level of lipoperoxidation and the instability of DNA increased. In HH, there was a reduction of teratozoospermia in melatonin-treated mice. Ibuprofen presented a protective effect on the same parameters as melatonin with both HI and HH. The quality of sperm DNA, fragmentation, unpacking and DNA stability diminished. In conclusion, reproductive damage elicited by HH or HI was partially ameliorated by simultaneous treatment with antiflogistic and/or antioxidant agents.

Effect of hypoxia on thallium kinetics in cultured chick myocardial cells

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Friedman, B.J.; Beihn, R.; Friedman, J.P.

1987-01-01

To assess the effect of hypoxia on cellular thallium-201 ( 201 Tl) uptake and washout independent of coronary flow, we studied thallium kinetics during normoxia and hypoxia in cultured chick ventricular cells. Monolayers of contracting ventricular cells grown on coverslips were placed in a chamber and perfused to asymptote with media containing 201 Tl. Perfusates were equilibrated with 5% CO 2 -95% air or 5% CO 2 -95% nitrogen for normoxia and hypoxia, respectively. Washout thallium kinetics were then observed during perfusion with unlabeled media. Twenty paired experiments were performed, randomly alternating the sequence of normoxia and hypoxia. Pharmacokinetics for thallium were determined by computer using standard formulae. Thallium uptake and washout were best described by assuming that intracellular thallium was contained within a single compartment. Cellular thallium uptake, as well as transfer rate constants for thallium uptake and for thallium washout during normoxia and hypoxia, were compared using paired t-tests. During normoxia and hypoxia, respectively, thallium uptake was 22 +/- 7% and 19 +/- 7% of asymptote (p less than 0.01); the compartmental rate constant for uptake by the cell was 0.16 +/- 0.07 min-1 and 0.15 +/- 0.06 min-1 (N.S.); and the transfer rate constant for washout from the cell was 0.26 +/- 0.06 min-1 and 0.23 +/- 0.05 min-1 (p less than 0.01). We conclude that there was a small (14%) decrease in thallium uptake during hypoxia. The rate of thallium uptake and washout was slightly less during hypoxia, although only the rate of washout was significantly less. These data show that cellular accumulation of thallium and the rate of washout of thallium were minimally decreased by hypoxia independent of blood flow

X-ray effects on bone marrow cells of white mice in conditions of hypoxia

International Nuclear Information System (INIS)

Devidze, M.A.

1981-01-01

X-ray effect on chromosomal system in mice under conditions of hypoxic hypoxia has been studied. It is shown that hypoxic hypoxia modifies the effect of X-ray at comparatively low irradiation doses (100 and 200 R). With the increase of the dose effect of ionizing irradiation on chromosomal system also increases, modifying effect of hypoxic hypoxia decreases and at 400 R disappears altogether. It is pointed out that in the process of ionizing effect modifying decrease in percentage of structural violations of chromosomes takes place mainly at the expense of all aberration types considered, but particularly percentage of multiple fragments decreases

[Protective effect of Uncaria rhynchophylla total alkaloids pretreatment on hippocampal neurons after acute hypoxia].

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Liu, Wei; Zhang, Zhao-qin; Zhao, Xiao-min; Gao, Yun-sheng

2006-05-01

To investigate the effect of Uncaria rhynchophylla total alkaloids (RTA) pretreatment on the voltage-gated sodium currents of the rat hippocampal neurons after acute hypoxia. Primary cultured hippocampal neurons were divided into RTA pre-treated and non-pretreated groups. Patch clamp whole-cell recording was used to compare the voltage-gated sodium current amplitude and threshold with those before hypoxia. After acute hypoxia, sodium current amplitude was significantly decreased and its threshold was upside. RTA pretreatment could inhibit the reduction of sodium current amplitude. RTA pretreatment alleviates the acute hypoxia-induced change of sodium currents, which may be one of the mechanisms for protective effect of RTA on cells.

Preclinical evidence of mitochondrial nicotinamide adenine dinucleotide as an effective alarm parameter under hypoxia

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Shi, Hua; Sun, Nannan; Mayevsky, Avraham; Zhang, Zhihong; Luo, Qingming

2014-01-01

Early detection of tissue hypoxia in the intensive care unit is essential for effective treatment. Reduced nicotinamide adenine dinucleotide (NADH) has been suggested to be the most sensitive indicator of tissue oxygenation at the mitochondrial level. However, no experimental evidence comparing the kinetics of changes in NADH and other physiological parameters has been provided. The aim of this study is to obtain the missing data in a systematic and reliable manner. We constructed four acute hypoxia models, including hypoxic hypoxia, hypemic hypoxia, circulatory hypoxia, and histogenous hypoxia, and measured NADH fluorescence, tissue reflectance, cerebral blood flow, respiration, and electrocardiography simultaneously from the induction of hypoxia until death. We found that NADH was not always the first onset parameter responding to hypoxia. The order of responses was mainly affected by the cause of hypoxia. However, NADH reached its alarm level earlier than the other monitored parameters, ranging from several seconds to >10 min. As such, we suggest that the NADH can be used as a hypoxia indicator, although the exact level that should be used must be further investigated. When the NADH alarm is detected, the body still has a chance to recover if appropriate and timely treatment is provided.

Comparing the effect of hypercapnia and hypoxia on the electroencephalogram during wakefulness.

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Wang, David; Yee, Brendon J; Wong, Keith K; Kim, Jong Won; Dijk, Derk-Jan; Duffin, James; Grunstein, Ronald R

2015-01-01

Hypoxia has been postulated as a key mechanism for neurocognitive impairment in sleep-disordered breathing. However, the effect of hypoxia on the electroencephalogram (EEG) is not clear. We examined quantitative EEG recordings from 20 normal volunteers under three 5-min ventilatory control protocols: progressive hypercapnia with iso-hyperoxia (pO2=150mmHg) (Protocol 1), progressive hypercapnia with iso-hypoxia (pO2=50mmHg) (Protocol 2), and progressive hypoxia with a CO2 scrubber in the circuit (Protocol 3). Each protocol started with a 5-min session of breathing room air as baseline. In Protocol 1, compared to its baseline, iso-hyperoxia hypercapnia led to a lower Alpha% and higher Delta/Alpha (D/A) ratio. Similarly, in Protocol 2, the iso-hypoxia hypercapnia induced a higher Delta%, a lower Alpha% and higher D/A ratio. No difference was found in any EEG spectral band including the D/A ratio when Protocols 1 & 2 were compared. In Protocol 3, the Delta%, Alpha% and D/A ratio recorded during hypoxia were not significantly different from baseline. We found that hypercapnia, but not hypoxia, may play a key role in slowing of the EEG in healthy humans. Hypercapnia may be a greater influence than hypoxia on brain neuroelectrical activities. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Radiosensitivity and effect of hypoxia in HPV positive head and neck cancer cells

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Sørensen, Brita Singers; Busk, Morten; Olthof, Nadine; Speel, Ernst-Jan; Horsman, Michael R.; Alsner, Jan; Overgaard, Jens

2013-01-01

Background and purpose: HPV associated Head and Neck Squamous Cell Carcinoma (HNSCC) represents a distinct subgroup of HNSCC characterized by a favorable prognosis and a distinct molecular biology. Previous data from the randomized DAHANCA 5 trial indicated that HPV positive tumors did not benefit from hypoxic modifications by Nimorazole during radiotherapy, whereas a significant benefit was observed in the HPV negative tumors. However, more studies have demonstrated equal frequencies of hypoxic tumors among HPV-positive and HPV-negative tumors. The aim of the present study was to determine radiosensitivity, the impact of hypoxia and the effect of Nimorazole in HPV positive and HPV negative cell lines. Materials and method: The used cell lines were: UDSCC2, UMSCC47 and UPCISCC90 (HPV positive) and FaDu DD , UTSCC33 and UTSCC5 (HPV negative). Cells were cultured under normoxic or hypoxic conditions, and gene expression levels of previously established hypoxia induced genes were assessed by qPCR. Cells were irradiated with various doses under normoxia, hypoxia or hypoxia +1 mM Nimorazole, and the clonogenic survival was determined. Results: The HPV positive and HPV negative cell lines exhibited similar patterns of upregulation of hypoxia induced genes in response to hypoxia. The HPV positive cell lines were up to 2.4 times more radiation sensitive than HPV negative cell lines. However, all HPV positive cells displayed the same response to hypoxia in radiosensitivity, with an OER in the range 2.3–2.9, and a sensitizer effect of Nimorazole of 1.13–1.29, similar to HPV negative cells. Conclusions: Although HPV positive cells had a markedly higher radiosensitivity compared to HPV negative cells, they displayed the same relative radioresistance under hypoxia and the same relative sensitizer effect of Nimorazole. The clinical observation that HPV positive patients do not seem to benefit from Nimorazole treatment is not due to inherent differences in hypoxia sensitivity

Hypoxia Potentiates Anabolic Effects of Exogenous Hyaluronic Acid in Rat Articular Cartilage

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Shohei Ichimaru

2016-06-01

Full Text Available Hyaluronic acid (HA is used clinically to treat osteoarthritis (OA, but its pharmacological effects under hypoxic conditions remain unclear. Articular chondrocytes in patients with OA are exposed to a hypoxic environment. This study investigated whether hypoxia could potentiate the anabolic effects of exogenous HA in rat articular cartilage and whether these mechanisms involved HA receptors. HA under hypoxic conditions significantly enhanced the expression of extracellular matrix genes and proteins in explant culture, as shown by real-time reverse transcription-polymerase chain reaction (RT-PCR, Western blotting, and dimethylmethylene blue (DMMB assays. Staining with Safranin-O and immunohistochemical staining with antibody to type II collagen were also enhanced in pellet culture. The expression of CD44 was increased by hypoxia and significantly suppressed by transfection with siRNAs targeting hypoxia-inducible factor 1 alpha (siHIF-1α. These findings indicate that hypoxia potentiates the anabolic effects of exogenous HA by a mechanism in which HIF-1α positively regulates the expression of CD44, enhancing the binding affinity for exogenous HA. The anabolic effects of exogenous HA may increase as OA progresses.

The effect of acute hypoxia on short-circuit current and epithelial resistivity in biopsies from human colon.

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Carra, Graciela E; Ibáñez, Jorge E; Saraví, Fernando D

2013-09-01

In isolated colonic mucosa, decreases in short-circuit current (ISC) and transepithelial resistivity (RTE) occur when hypoxia is either induced at both sides or only at the serosal side of the epithelium. We assessed in human colon biopsies the sensitivity to serosal-only hypoxia and mucosal-only hypoxia and whether Na, K-ATPase blockade with ouabain interacts with hypoxia. Biopsy material from patients undergoing colonoscopy was mounted in an Ussing chamber for small samples (1-mm2 window). In a series of experiments we assessed viability and the electrical response to the mucolytic, dithiothreitol (1 mmol/l). In a second series, we explored the effect of hypoxia without and with ouabain. In a third series, we evaluated the response to a cycle of hypoxia and reoxygenation induced at the serosal or mucosal side while keeping the oxygenation of the opposite side. 1st series: Dithiothreitol significantly decreased the unstirred layer and ISC but increased RTE. 2nd series: Both hypoxia and ouabain decreased ISC, but ouabain increased RTE and this effect on RTE prevailed even during hypoxia. 3rd series: Mucosal hypoxia caused lesser decreases of ISC and RTE than serosal hypoxia; in the former, but not in the latter, recovery was complete upon reoxygenation. In mucolytic concentration, dithiothreitol modifies ISC and RTE. Oxygen supply from the serosal side is more important to sustain ISC and RTE in biopsy samples. The different effect of hypoxia and Na, K-ATPase blockade on RTE suggests that their depressing effect on ISC involves different mechanisms.

Effects of hypoxia and ocean acidification on the upper thermal niche boundaries of coral reef fishes.

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Ern, Rasmus; Johansen, Jacob L; Rummer, Jodie L; Esbaugh, Andrew J

2017-07-01

Rising ocean temperatures are predicted to cause a poleward shift in the distribution of marine fishes occupying the extent of latitudes tolerable within their thermal range boundaries. A prevailing theory suggests that the upper thermal limits of fishes are constrained by hypoxia and ocean acidification. However, some eurythermal fish species do not conform to this theory, and maintain their upper thermal limits in hypoxia. Here we determine if the same is true for stenothermal species. In three coral reef fish species we tested the effect of hypoxia on upper thermal limits, measured as critical thermal maximum (CT max ). In one of these species we also quantified the effect of hypoxia on oxygen supply capacity, measured as aerobic scope (AS). In this species we also tested the effect of elevated CO 2 (simulated ocean acidification) on the hypoxia sensitivity of CT max We found that CT max was unaffected by progressive hypoxia down to approximately 35 mmHg, despite a substantial hypoxia-induced reduction in AS. Below approximately 35 mmHg, CT max declined sharply with water oxygen tension ( P w O 2 ). Furthermore, the hypoxia sensitivity of CT max was unaffected by elevated CO 2 Our findings show that moderate hypoxia and ocean acidification do not constrain the upper thermal limits of these tropical, stenothermal fishes. © 2017 The Author(s).

Guinea Pig as a Model to Study the Carotid Body Mediated Chronic Intermittent Hypoxia Effects.

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Docio, Inmaculada; Olea, Elena; Prieto-LLoret, Jesus; Gallego-Martin, Teresa; Obeso, Ana; Gomez-Niño, Angela; Rocher, Asuncion

2018-01-01

Clinical and experimental evidence indicates a positive correlation between chronic intermittent hypoxia (CIH), increased carotid body (CB) chemosensitivity, enhanced sympatho-respiratory coupling and arterial hypertension and cardiovascular disease. Several groups have reported that both the afferent and efferent arms of the CB chemo-reflex are enhanced in CIH animal models through the oscillatory CB activation by recurrent hypoxia/reoxygenation episodes. Accordingly, CB ablation or denervation results in the reduction of these effects. To date, no studies have determined the effects of CIH treatment in chemo-reflex sensitization in guinea pig, a rodent with a hypofunctional CB and lacking ventilatory responses to hypoxia. We hypothesized that the lack of CB hypoxia response in guinea pig would suppress chemo-reflex sensitization and thereby would attenuate or eliminate respiratory, sympathetic and cardiovascular effects of CIH treatment. The main purpose of this study was to assess if guinea pig CB undergoes overactivation by CIH and to correlate CIH effects on CB chemoreceptors with cardiovascular and respiratory responses to hypoxia. We measured CB secretory activity, ventilatory parameters, systemic arterial pressure and sympathetic activity, basal and in response to acute hypoxia in two groups of animals: control and 30 days CIH exposed male guinea pigs. Our results indicated that CIH guinea pig CB lacks activity elicited by acute hypoxia measured as catecholamine (CA) secretory response or intracellular calcium transients. Plethysmography data showed that only severe hypoxia (7% O 2 ) and hypercapnia (5% CO 2 ) induced a significant increased ventilatory response in CIH animals, together with higher oxygen consumption. Therefore, CIH exposure blunted hyperventilation to hypoxia and hypercapnia normalized to oxygen consumption. Increase in plasma CA and superior cervical ganglion CA content was found, implying a CIH induced sympathetic hyperactivity. CIH

Effect of superoxide anion scavenger on rat hearts with chronic intermittent hypoxia.

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Pai, Peiying; Lai, Ching Jung; Lin, Ching-Yuang; Liou, Yi-Fan; Huang, Chih-Yang; Lee, Shin-Da

2016-04-15

Only very limited information regarding the protective effects of the superoxide anion scavenger on chronic intermittent hypoxia-induced cardiac apoptosis is available. The purpose of this study is to evaluate the effects of the superoxide anion scavenger on cardiac apoptotic and prosurvival pathways in rats with sleep apnea. Forty-two Sprague-Dawley rats were divided into three groups, rats with normoxic exposure (Control, 21% O2, 1 mo), rats with chronic intermittent hypoxia exposure (Hypoxia, 3-7% O2vs. 21% O2per 40 s cycle, 8 h per day, 1 mo), and rats with pretreatment of the superoxide anion scavenger and chronic intermittent hypoxia exposure (Hypoxia-O2 (-)-Scavenger, MnTMPyP pentachloride, 1 mg/kg ip per day; 3-7% O2vs. 21% O2per 40 s cycle, 8 h per day, 1 mo) at 5-6 mo of age. After 1 mo, the protein levels and apoptotic cells of excised hearts from three groups were measured by Western blotting and terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) assay. The superoxide anion scavenger decreased hypoxia-induced myocardial architecture abnormalities, left ventricular hypertrophy, and TUNEL-positive apoptosis. The superoxide anion scavenger decreased hypoxia-induced Fas ligand, Fas death receptors, Fas-associated death domain (FADD), activated caspase-8, and activated caspase-3 (Fas-dependent apoptotic pathway) as well as Bad, activated caspase-9 and activated caspase-3 (mitochondria-dependent apoptotic pathway), endonuclease G (EndoG), apoptosis-inducing factor (AIF), and TUNEL-positive apoptosis. The superoxide anion scavenger increased IGF-1, IGF-1R, p-PI3k, p-Akt, p-Bad, Bcl-2, and Bcl-xL (survival pathway). Our findings imply that the superoxide anion scavenger might prevent cardiac Fas-mediated and mitochondrial-mediated apoptosis and enhance the IGF-1-related survival pathway in chronic intermittent hypoxia. The superoxide anion scavenger may prevent chronic sleep apnea-enhanced cardiac apoptotic pathways and enhances

Effects of in vitro hypoxia on depolarization-stimulated accumulation of inositol phosphates in synaptosomes

International Nuclear Information System (INIS)

Huang, H.M.; Gibson, G.E.

1989-01-01

The effects of potassium and in vitro histotoxic hypoxia on phosphatidylinositol turnover in rat cortical synaptosomes were determined. [2- 3 H] Inositol prelabelled rat synaptosomes were prepared from cerebral cortex slices that had been incubated with [2- 3 H] inositol. Depolarization with 60 mM KCl increased [2- 3 H] inositol phosphates in a time dependent manner. Depolarization with 60 mM KCl increased [2- 3 H]inositol trisphosphate transiently at 5 s. K + induced rapid formation of [2- 3 H] inositol monophosphate with time. One minute of hypoxia enhance sium-stimulate [2 3 H]inositol bisphosphate and maintained an elevated level for at least 5 min. K + stimulated gradual formation of [2- 3 H] inositol monophosphate with time. One minute of hypoxia enhanced potassium-stimulated [2- 3 H] inositol bisphosphate formation. However, 30 min of hypoxia impaired potassium-stimulated accumulation of [2- 3 H]inositol phosphates. The effects of histotoxic hypoxia were all dependent upon calcium in the medium and on K + -depolarization. Thus, hypoxia altered the K + induced accumulation of inositol phosphates in prelabelled synaptosomes in a time dependent, biphasic manner that was calcium dependent

Normobaric Hypoxia and Submaximal Exercise Effects on Running Memory and Mood State in Women.

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Seo, Yongsuk; Gerhart, Hayden D; Stavres, Jon; Fennell, Curtis; Draper, Shane; Glickman, Ellen L

2017-07-01

An acute bout of exercise can improve cognitive function in normoxic and hypoxic conditions. However, limited research supports the improvement of cognitive function and mood state in women. The purpose of this study was to examine the effects of hypoxia and exercise on working memory and mood state in women. There were 15 healthy women (age = 22 ± 2 yr) who completed the Automated Neuropsychological Assessment Metrics-4th Edition (ANAM), including the Running Memory Continuous Performance Task (RMCPT) and Total Mood Disturbance (TMD) in normoxia (21% O2), at rest in normoxia and hypoxia (12.5% O2), and during cycling exercise at 60% and 40% Vo2max in hypoxia. RMCPT was not significantly impaired at 30 (100.3 ± 17.2) and 60 (96.6 ± 17.3) min rest in hypoxia compared to baseline in normoxia (97.0 ± 17.0). However, RMCPT was significantly improved during exercise (106.7 ± 20.8) at 60% Vo2max compared to 60 min rest in hypoxia. Following 30 (-89.4 ± 48.3) and 60 min of exposure to hypoxia (-79.8 ± 55.9) at rest, TMD was impaired compared with baseline (-107.1 ± 46.2). TMD was significantly improved during exercise (-108.5 ± 42.7) at 40% Vo2max compared with 30 min rest in hypoxia. Also, RMCPT was significantly improved during exercise (104.0 ± 19.1) at 60% Vo2max compared to 60 min rest in hypoxia (96.6 ± 17.3). Hypoxia and an acute bout of exercise partially influence RMCPT and TMD. Furthermore, a moderate-intensity bout of exercise (60%) may be a more potent stimulant for improving cognitive function than low-intensity (40%) exercise. The present data should be considered by aeromedical personnel performing cognitive tasks in hypoxia.Seo Y, Gerhart HD, Stavres J, Fennell C, Draper S, Glickman EL. Normobaric hypoxia and submaximal exercise effects on running memory and mood state in women. Aerosp Med Hum Perform. 2017; 88(7):627-632.

Hypoxia and hypoxia inducible factor-1α are required for normal endometrial repair during menstruation.

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Maybin, Jacqueline A; Murray, Alison A; Saunders, Philippa T K; Hirani, Nikhil; Carmeliet, Peter; Critchley, Hilary O D

2018-01-23

Heavy menstrual bleeding (HMB) is common and debilitating, and often requires surgery due to hormonal side effects from medical therapies. Here we show that transient, physiological hypoxia occurs in the menstrual endometrium to stabilise hypoxia inducible factor 1 (HIF-1) and drive repair of the denuded surface. We report that women with HMB have decreased endometrial HIF-1α during menstruation and prolonged menstrual bleeding. In a mouse model of simulated menses, physiological endometrial hypoxia occurs during bleeding. Maintenance of mice under hyperoxia during menses decreases HIF-1α induction and delays endometrial repair. The same effects are observed upon genetic or pharmacological reduction of endometrial HIF-1α. Conversely, artificial induction of hypoxia by pharmacological stabilisation of HIF-1α rescues the delayed endometrial repair in hypoxia-deficient mice. These data reveal a role for HIF-1 in the endometrium and suggest its pharmacological stabilisation during menses offers an effective, non-hormonal treatment for women with HMB.

Pyruvate induces transient tumor hypoxia by enhancing mitochondrial oxygen consumption and potentiates the anti-tumor effect of a hypoxia-activated prodrug TH-302.

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Yoichi Takakusagi

Full Text Available BACKGROUND: TH-302 is a hypoxia-activated prodrug (HAP of bromo isophosphoramide mustard that is selectively activated within hypoxic regions in solid tumors. Our recent study showed that intravenously administered bolus pyruvate can transiently induce hypoxia in tumors. We investigated the mechanism underlying the induction of transient hypoxia and the combination use of pyruvate to potentiate the anti-tumor effect of TH-302. METHODOLOGY/RESULTS: The hypoxia-dependent cytotoxicity of TH-302 was evaluated by a viability assay in murine SCCVII and human HT29 cells. Modulation in cellular oxygen consumption and in vivo tumor oxygenation by the pyruvate treatment was monitored by extracellular flux analysis and electron paramagnetic resonance (EPR oxygen imaging, respectively. The enhancement of the anti-tumor effect of TH-302 by pyruvate treatment was evaluated by monitoring the growth suppression of the tumor xenografts inoculated subcutaneously in mice. TH-302 preferentially inhibited the growth of both SCCVII and HT29 cells under hypoxic conditions (0.1% O2, with minimal effect under aerobic conditions (21% O2. Basal oxygen consumption rates increased after the pyruvate treatment in SCCVII cells in a concentration-dependent manner, suggesting that pyruvate enhances the mitochondrial respiration to consume excess cellular oxygen. In vivo EPR oxygen imaging showed that the intravenous administration of pyruvate globally induced the transient hypoxia 30 min after the injection in SCCVII and HT29 tumors at the size of 500-1500 mm(3. Pretreatment of SCCVII tumor bearing mice with pyruvate 30 min prior to TH-302 administration, initiated with small tumors (∼ 550 mm(3, significantly delayed tumor growth. CONCLUSIONS/SIGNIFICANCE: Our in vitro and in vivo studies showed that pyruvate induces transient hypoxia by enhancing mitochondrial oxygen consumption in tumor cells. TH-302 therapy can be potentiated by pyruvate pretreatment if started at the

Pyruvate induces transient tumor hypoxia by enhancing mitochondrial oxygen consumption and potentiates the anti-tumor effect of a hypoxia-activated prodrug TH-302.

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Takakusagi, Yoichi; Matsumoto, Shingo; Saito, Keita; Matsuo, Masayuki; Kishimoto, Shun; Wojtkowiak, Jonathan W; DeGraff, William; Kesarwala, Aparna H; Choudhuri, Rajani; Devasahayam, Nallathamby; Subramanian, Sankaran; Munasinghe, Jeeva P; Gillies, Robert J; Mitchell, James B; Hart, Charles P; Krishna, Murali C

2014-01-01

TH-302 is a hypoxia-activated prodrug (HAP) of bromo isophosphoramide mustard that is selectively activated within hypoxic regions in solid tumors. Our recent study showed that intravenously administered bolus pyruvate can transiently induce hypoxia in tumors. We investigated the mechanism underlying the induction of transient hypoxia and the combination use of pyruvate to potentiate the anti-tumor effect of TH-302. The hypoxia-dependent cytotoxicity of TH-302 was evaluated by a viability assay in murine SCCVII and human HT29 cells. Modulation in cellular oxygen consumption and in vivo tumor oxygenation by the pyruvate treatment was monitored by extracellular flux analysis and electron paramagnetic resonance (EPR) oxygen imaging, respectively. The enhancement of the anti-tumor effect of TH-302 by pyruvate treatment was evaluated by monitoring the growth suppression of the tumor xenografts inoculated subcutaneously in mice. TH-302 preferentially inhibited the growth of both SCCVII and HT29 cells under hypoxic conditions (0.1% O2), with minimal effect under aerobic conditions (21% O2). Basal oxygen consumption rates increased after the pyruvate treatment in SCCVII cells in a concentration-dependent manner, suggesting that pyruvate enhances the mitochondrial respiration to consume excess cellular oxygen. In vivo EPR oxygen imaging showed that the intravenous administration of pyruvate globally induced the transient hypoxia 30 min after the injection in SCCVII and HT29 tumors at the size of 500-1500 mm(3). Pretreatment of SCCVII tumor bearing mice with pyruvate 30 min prior to TH-302 administration, initiated with small tumors (∼ 550 mm(3)), significantly delayed tumor growth. Our in vitro and in vivo studies showed that pyruvate induces transient hypoxia by enhancing mitochondrial oxygen consumption in tumor cells. TH-302 therapy can be potentiated by pyruvate pretreatment if started at the appropriate tumor size and oxygen concentration.

Pulmonary antioxidants exert differential protective effects against ...

Indian Academy of Sciences (India)

Unknown

PM collections from both urban and industrial sites caused 50% oxidative degradation of DNA in vitro at concentrations as low ... chemical analysis in order that progress can be made in ... One popular hypothesis is that PM exerts toxic effects.

Slit2 ameliorates renal inflammation and fibrosis after hypoxia-and lipopolysaccharide-induced epithelial cells injury in vitro

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Zhou, Xiangjun [Department of Urology, Taihe Hospital, Hubei University of Medicine, Hubei (China); Yao, Qisheng, E-mail: yymcyqs@126.com [Department of Urology, Taihe Hospital, Hubei University of Medicine, Hubei (China); Sun, Xinbo; Gong, Xiaoxin; Yang, Yong; Chen, Congbo [Department of Urology, Taihe Hospital, Hubei University of Medicine, Hubei (China); Shan, Guang [Department of Urology, Renmin Hospital of Wuhan University, Hubei (China)

2017-03-01

Hypoxic acute kidney injury (AKI) is often incompletely repaired and leads to chronic kidney disease (CKD), which is characterized by tubulointerstitial inflammation and fibrosis. The Slit2 family of secreted glycoproteins is expressed in the kidney, it has been shown to exert an anti-inflammatory activity and prevent ischemic renal injury in vivo. However, whether Slit2 reduces renal fibrosis and inflammation after hypoxic and inflammatory epithelial cells injury in vitro remains unknown. In this study, we aimed to evaluate whether Slit2 ameliorated fibrosis and inflammation in two renal epithelial cells line challenged with hypoxia and lipopolysaccharide (LPS). Renal epithelial cells were treated with hypoxia and LPS to induce cell injury. Hoechst staining and Western blot analysis was conducted to examine epithelial cells injury. Immunofluorescence staining and Western blot analysis was performed to evaluate tubulointerstitial fibrosis. Real-time polymerase chain reaction (PCR) tested the inflammatory factor interleukin (IL)−1β and tumor necrosis factor (TNF)-α, and Western blot analysis determined the hypoxia-inducible factor (HIF)−1α, Toll-like receptor 4 (TLR4) and nuclear factor (NF)-κB. Results revealed that hypoxia induced epithelial cells apoptosis, inflammatory factor IL-1β and TNF-α release and tubulointerstitial fibrosis. LPS could exacerbate hypoxia -induced epithelial cells apoptosis, IL-1β and TNF-α release and fibrosis. Slit2 reduced the expression of fibronectin, the rate of epithelial cell apoptosis, and the expression of inflammatory factor. Slit2 could also inhibit the expression of TLR4 and NF-κB, but not the expression of HIF-1α. Therefore, Slit2 attenuated inflammation and fibrosis after LPS- and hypoxia-induced epithelial cells injury via the TLR4/NF-κB signaling pathway, but not depending on the HIF-1α signaling pathway. - Highlights: • Slit2 ameliorates inflammation after hypoxia-and LPS-induced epithelial cells injury

Effects of natural and human-induced hypoxia on coastal benthos

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L. A. Levin

2009-10-01

Full Text Available Coastal hypoxia (defined here as <1.42 ml L⁻¹; 62.5 μM; 2 mg L⁻¹, approx. 30% oxygen saturation develops seasonally in many estuaries, fjords, and along open coasts as a result of natural upwelling or from anthropogenic eutrophication induced by riverine nutrient inputs. Permanent hypoxia occurs naturally in some isolated seas and marine basins as well as in open slope oxygen minimum zones. Responses of benthos to hypoxia depend on the duration, predictability, and intensity of oxygen depletion and on whether H₂S is formed. Under suboxic conditions, large mats of filamentous sulfide oxidizing bacteria cover the seabed and consume sulfide. They are hypothesized to provide a detoxified microhabitat for eukaryotic benthic communities. Calcareous foraminiferans and nematodes are particularly tolerant of low oxygen concentrations and may attain high densities and dominance, often in association with microbial mats. When oxygen is sufficient to support metazoans, small, soft-bodied invertebrates (typically annelids, often with short generation times and elaborate branchial structures, predominate. Large taxa are more sensitive than small taxa to hypoxia. Crustaceans and echinoderms are typically more sensitive to hypoxia, with lower oxygen thresholds, than annelids, sipunculans, molluscs and cnidarians. Mobile fish and shellfish will migrate away from low-oxygen areas. Within a species, early life stages may be more subject to oxygen stress than older life stages.

Hypoxia alters both the structure and function of benthic communities, but effects may differ with regional hypoxia history. Human-caused hypoxia is generally linked to eutrophication, and occurs adjacent to watersheds with large populations or agricultural activities. Many occurrences are seasonal, within estuaries, fjords or enclosed seas of the North Atlantic and the NW Pacific Oceans. Benthic faunal responses, elicited at oxygen levels below

Cytoprotective effects of atmospheric-pressure plasmas against hypoxia-induced neuronal injuries

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Yan, Xu; Meng, Zhaozhong; Ouyang, Jiting; Qiao, Yajun; Li, Jiaxin; Jia, Mei; Yuan, Fang; (Ken Ostrikov, Kostya

2018-02-01

Atmospheric pressure plasma jet (APPJ) has recently been the focus of cytoprotective research due to the physiological roles of ROS and RNS. In the current study, we investigated the effect of APPJ treatment on the hypoxia (1% oxygen) induced cell injuries. SH-SY5Y cells were treated by APPJ for different duration and incubated in normoxic condition (20% oxygen) for 5 h followed by 24 h hypoxia treatment. Cell viability was evaluated by lactate dehydrogenase (LDH) release and further monitored using the electric cell-substrate impedance sensing (ECIS) system after APPJ treatment. Results showed that APPJ could reduce cell injuries after 24 h hypoxia, which was consistent with the ECIS results. Furthermore, extracellular NO and H2O2 production was significantly increased with the APPJ treatment. It was also interesting to find that APPJ treatment reduced SH-SY5Y cells proliferation in the hypoxic microenvironment during the first 20 h of hypoxia. Although more work was still need to clarify whether the cell viability maintenance was related to the cell proliferation during hypoxia, our results provide the first evidence of real-time cell viability changes after APPJ treatment under both normoxic and hypoxic conditions, which could provide evidence for the neuroprotective applications of APPJ.

Effects of manganese and hypoxia on coelomocyte renewal in the echinoderm, Asterias rubens (L.)

International Nuclear Information System (INIS)

Oweson, Carolina; Li Chenghua; Soederhaell, Irene; Hernroth, Bodil

2010-01-01

Manganese (Mn) is a naturally abundant metal and particularly so in soft-bottom oceanic sediments where it generally occurs bound in a four-valent colloidal state as MnO 2 . When hypoxic conditions occur in bottom waters, the metal reduces to the bioavailable ion Mn 2+ and can reach concentrations known to have immunotoxic effects in the crustacean Nephrops norvegicus, reducing numbers of circulating haemocytes as a consequence. However, we have previously shown that Mn seems to have a contrasting effect on the echinoderm Asterias rubens in which it triggers the proliferation of haematopoietic cells and increases coelomocyte numbers. Since elevated Mn levels mostly co-occur with hypoxia in nature, here we investigated whether hypoxia has a negative effect on haematopoiesis. Proliferation and differentiation of coelomocytes and cells in the coelomic epithelium of A. rubens were compared after 3 days of exposure to realistic levels of Mn, hypoxia or a combination of these two parameters. We can confirm that Mn elevated numbers of coelomocytes and increased proliferation of epithelial cells, but hypoxia did not affect these levels. However, hypoxia did affect differentiation of these cells as judged by investigating the expression of a Runt domain transcription factor, which was also cloned and sequenced. Through comparative quantification using a real time PCR technique, we found that exposure to hypoxia had a clearly stimulating effect on mRNA expression of Runt gene in both coelomocytes and epithelial cells. These results indicate that during hypoxic conditions the composition of coelomocyte sub-populations changed.

Hypoxic stress up-regulates the expression of Toll-like receptor 4 in macrophages via hypoxia-inducible factor.

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Kim, So Young; Choi, Yong Jun; Joung, Sun Myung; Lee, Byung Ho; Jung, Yi-Sook; Lee, Joo Young

2010-04-01

Toll-like receptors (TLRs) are germline-encoded innate immune receptors that recognize invading micro-organisms and induce immune and inflammatory responses. Deregulation of TLRs is known to be closely linked to various immune disorders and inflammatory diseases. Cells at sites of inflammation are exposed to hypoxic stress, which further aggravates inflammatory processes. We have examined if hypoxic stress modulates the TLR activity of macrophages. Hypoxia and CoCl(2) (a hypoxia mimetic) enhanced the expression of TLR4 messenger RNA and protein in macrophages (RAW264.7 cells), whereas the messenger RNA of other TLRs was not increased. To determine the underlying mechanism, we investigated the role of hypoxia-inducible factor 1 (HIF-1) in the regulation of TLR4 expression. Knockdown of HIF-1alpha expression by small interfering RNA inhibited hypoxia-induced and CoCl(2)-induced TLR4 expression in macrophages, while over-expression of HIF-1alpha potentiated TLR4 expression. Chromatin immunoprecipitation assays revealed that HIF-1alpha binds to the TLR4 promoter region under hypoxic conditions. In addition, deletion or mutation of a putative HIF-1-binding motif in the TLR4 promoter greatly attenuated HIF-1alpha-induced TLR4 promoter reporter expression. Up-regulation of TLR4 expression by hypoxic stress enhanced the response of macrophages to lipopolysaccharide, resulting in increased expression of cyclooxygenase-2, interleukin-6, regulated on activation normal T cell expressed and secreted, and interferon-inducible protein-10. These results demonstrate that TLR4 expression in macrophages is up-regulated via HIF-1 in response to hypoxic stress, suggesting that hypoxic stress at sites of inflammation enhances susceptibility to subsequent infection and inflammatory signals by up-regulating TLR4.

Urokinase receptor expression on human microvascular endothelial cells is increased by hypoxia: Implications for capillary-like tube formation in a fibrin matrix

NARCIS (Netherlands)

Kroon, M.E.; Koolwijk, P.; Vecht, B. van der; Hinsbergh, V.W.M. van

2000-01-01

Hypoxia stimulates angiogenesis, the formation of new blood vessels. This study evaluates the direct effect of hypoxia (1% oxygen) on the angiogenic response of human microvascular endothelial cells (hMVECs) seeded on top of a 3-dimensional fibrin matrix, hMVECs stimulated with fibroblast growth

Contrasting effects of hypoxia on copper toxicity during development in the three-spined stickleback (Gasterosteus aculeatus).

Science.gov (United States)

Fitzgerald, Jennifer A; Katsiadaki, Ioanna; Santos, Eduarda M

2017-03-01

Hypoxia is a global problem in aquatic systems and often co-occurs with pollutants. Despite this, little is known about the combined effects of these stressors on aquatic organisms. The objective of this study was to investigate the combined effects of hypoxia and copper, a toxic metal widespread in the aquatic environment. We used the three-spined stickleback (Gasterosteus aculeatus) as a model because of its environmental relevance and amenability for environmental toxicology studies. We focused on embryonic development as this is considered to be a sensitive life stage to environmental pollution. We first investigated the effects of hypoxia alone on stickleback development to generate the information required to design subsequent studies. Our data showed that exposure to low oxygen concentrations (24.7 ± 0.9% air saturation; AS) resulted in strong developmental delays and increased mortalities, whereas a small decrease in oxygen (75.0 ± 0.5%AS) resulted in premature hatching. Stickleback embryos were then exposed to a range of copper concentrations under hypoxia (56.1 ± 0.2%AS) or normoxia (97.6 ± 0.1%AS), continuously, from fertilisation to free swimming larvae. Hypoxia caused significant changes in copper toxicity throughout embryonic development. Prior to hatching, hypoxia suppressed the occurrence of mortalities, but after hatching hypoxia significantly increased copper toxicity. Interestingly, when exposures were conducted only after hatching, the onset of copper-induced mortalities was delayed under hypoxia compared to normoxia, but after 48 h, copper was more toxic to hatched embryos under hypoxia. This is the second species for which the protective effect of hypoxia on copper toxicity prior to hatching, followed by its exacerbating effect after hatching is demonstrated, suggesting the hypothesis that this pattern may be common for teleost species. Our research highlights the importance of considering the interactions between multiple

Intermittent hypercapnic hypoxia during sleep does not induce ventilatory long-term facilitation in healthy males.

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Deacon, Naomi L; McEvoy, R Doug; Stadler, Daniel L; Catcheside, Peter G

2017-09-01

Intermittent hypoxia-induced ventilatory neuroplasticity is likely important in obstructive sleep apnea pathophysiology. Although concomitant CO 2 levels and arousal state critically influence neuroplastic effects of intermittent hypoxia, no studies have investigated intermittent hypercapnic hypoxia effects during sleep in humans. Thus the purpose of this study was to investigate if intermittent hypercapnic hypoxia during sleep induces neuroplasticity (ventilatory long-term facilitation and increased chemoreflex responsiveness) in humans. Twelve healthy males were exposed to intermittent hypercapnic hypoxia (24 × 30 s episodes of 3% CO 2 and 3.0 ± 0.2% O 2 ) and intermittent medical air during sleep after 2 wk washout period in a randomized crossover study design. Minute ventilation, end-tidal CO 2 , O 2 saturation, breath timing, upper airway resistance, and genioglossal and diaphragm electromyograms were examined during 10 min of stable stage 2 sleep preceding gas exposure, during gas and intervening room air periods, and throughout 1 h of room air recovery. There were no significant differences between conditions across time to indicate long-term facilitation of ventilation, genioglossal or diaphragm electromyogram activity, and no change in ventilatory response from the first to last gas exposure to suggest any change in chemoreflex responsiveness. These findings contrast with previous intermittent hypoxia studies without intermittent hypercapnia and suggest that the more relevant gas disturbance stimulus of concomitant intermittent hypercapnia frequently occurring in sleep apnea influences acute neuroplastic effects of intermittent hypoxia. These findings highlight the need for further studies of intermittent hypercapnic hypoxia during sleep to clarify the role of ventilatory neuroplasticity in the pathophysiology of sleep apnea. NEW & NOTEWORTHY Both arousal state and concomitant CO 2 levels are known modulators of the effects of intermittent hypoxia on

Effect of Hypoxia and Bedrest on Peripheral Vasoconstriction

Science.gov (United States)

McDonnell, Adam C.; Mekjavic, Igor B.; Dolenc-Groselj, Leja; Jaki Mekjavic, Polona; Eiken, Ola

2013-02-01

Future planetary habitats may expose astronauts to both microgravity and hypobaric hypoxia, both inducing a reduction in peripheral perfusion. Peripheral temperature changes have been linked to sleep onset and quality [5]. However, it is still unknown what effect combining hypoxia and bedrest has on this relationship. Eleven male participants underwent three 10-day campaigns in a randomized manner: 1) normobaric hypoxic ambulatory confinement (HAmb); 2) normobaric hypoxic bed rest (HBR); 3) normobaric normoxic bed rest (NBR). There was no change in skin temperature gradient between the calf and toes, an index of peripheral perfusion (Δ Tc-t), over the 10-d period in the HAmb trial. However, there was a significant increase (psleep onset and/or architecture. These data support the theory that circadian changes in temperature are functionally linked to sleepiness [1].

Induction of adipocyte-like phenotype in human mesenchymal stem cells by hypoxia

DEFF Research Database (Denmark)

Fink, Trine; Abildtrup, Lisbeth Ann; Fogd, Kirsten

2004-01-01

Human mesenchymal stem cells (hMSCs) have the capacity to differentiate along several pathways to form bone, cartilage, tendon, muscle, and adipose tissues. The adult hMSCs reside in vivo in the bone marrow in niches where oxygen concentration is far below the ambient air, which is the most...... commonly encountered laboratory condition. The study reported here was designed to determine whether oxygen has a role in the differentiation of hMSCs into adipocytes. Indeed, when exposed to atmosphere containing only 1% of oxygen, the formation of adipocyte-like phenotype with cytoplasmic lipid....... High level of induction, however, was observed with the PPAR-gamma-induced angiopoietin-related gene, PGAR. The lack of an adipocyte-specific transcription pattern thus indicates that despite accumulation of the lipid, true adipogenic differentiation did not take place. In conclusion, hypoxia appears...

[Effects of exogenous spermidine on Cucumis sativus L. seedlings photosynthesis under root zone hypoxia stress].

Science.gov (United States)

Wang, Tian; Wang, Suping; Guo, Shirong; Sun, Yanjun

2006-09-01

With water culture, this paper studied the effects of exogenous spermidine (Spd) on the net photosynthetic rate (Pn), intercellular CO2 concentrations (Ci), stomatal conductance (Gs), transpiration rate (Tr), apparent quantum yield (phi c), and carboxylation efficiency (CE) of cucumber seedlings tinder hypoxia stress. The results showed that the Pn decreased gradually under hypoxia stress, and reached the minimum 10 days after by 63. 33% of the control. Compared with that of hypoxia-stressed plants, the Pn after 10 days application of exogenous Spd increased 1.25 times. A negative correlation (R2 = 0.4730 - 0.7118) was found between Pn and Ci. Gs and Tr changed in wider ranges, which decreased under hypoxia-stress, but increased under hypoxia-stress plus exogenous Spd application. There was a significant positive correlation between Gs and Tr (R2 = 0.7821 - 0.9458), but these two parameters had no significant correlation with Pn; Hypoxia stress induced a decrease of phi c and CE by 63.01% and 72.33%, respectively, while hypoxia stress plus exogenous Spd application made phi c and CE increase by 23% and 14%, respectively. The photo-inhibition of cucumber seedlings under hypoxia stress was mainly caused by non-stomatal limitation, while exogenous Spd alleviated the hypoxia stress by repairing photosynthesis system.

Effects of prenatal hypoxia on schizophrenia-related phenotypes in heterozygous reeler mice: a gene × environment interaction study.

Science.gov (United States)

Howell, Kristy R; Pillai, Anilkumar

2014-08-01

Both genetic and environmental factors play important roles in the pathophysiology of schizophrenia. Although prenatal hypoxia is a potential environmental factor implicated in schizophrenia, very little is known about the consequences of combining models of genetic risk factor with prenatal hypoxia. Heterozygous reeler (haploinsufficient for reelin; HRM) and wild-type (WT) mice were exposed to prenatal hypoxia (9% oxygen for two hour) or normoxia at embryonic day 17 (E17). Behavioral (Prepulse inhibition, Y-maze and Open field) and functional (regional volume in frontal cortex and hippocampus as well as hippocampal blood flow) tests were performed at 3 months of age. The levels of hypoxia and stress-related molecules such as hypoxia-inducible factor-1 α (HIF-1α), vascular endothelial factor (VEGF), VEGF receptor-2 (VEGFR2/Flk1) and glucocorticoid receptor (GR) were examined in frontal cortex and hippocampus at E18, 1 month and 3 months of age. In addition, serum VEGF and corticosterone levels were also examined. Prenatal hypoxia induced anxiety-like behavior in both HRM and WT mice. A significant reduction in hippocampal blood flow, but no change in brain regional volume was observed following prenatal hypoxia. Significant age and region-dependent changes in HIF-1α, VEGF, Flk1 and GR were found following prenatal hypoxia. Serum VEGF and corticosterone levels were found decreased following prenatal hypoxia. None of the above prenatal hypoxia-induced changes were either diminished or exacerbated due to reelin deficiency. These results argue against any gene-environment interaction between hypoxia and reelin deficiency. Copyright © 2014 Elsevier B.V. and ECNP. All rights reserved.

Role of hypoxia and hypoxia inducible factor in physiological and pathological conditions

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Mozhgan Jahani

2017-11-01

Full Text Available Introduction: Organisms are exposed to oxygen deprivation (Hypoxia in various physiological and pathological conditions. There are different conserve evolutionary responses to counterview with this stress that primary transcriptional response to stress related to hypoxia is interceded by hypoxia-inducible factor (HIF-1 in mammals. This factor can regulate different genes that have essential roles in adaptation to this condition. In this review, the role of this factor in physiological and pathological conditions under hypoxic condition has been evaluated after examining structural features and regulation characteristics of HIF-1. Methods: First, articles related to the keywords of hypoxia and HIF-1 (from 1991-2016 were searched from valid databases such as Springer Link, Google Scholar, PubMed and Science direct. Then, the articles correlated with hypoxia, HIF-1 and their roles in physiological and pathological conditions (120 articles were searched and just 64 articles were selected for this study. Result: According to studies, there are different genes in cells and organs that can be regulated by HIF-1. Activation of genes expression by this protein occurs through its linkage to cis-acting of 50 base pair hypoxia response element (HRE region located in their promotor and enhancer. Depending on circumstances, activation of these genes can be beneficial or harmful. Conclusion: Activation of different genes in hypoxia by HIF-1 has different effects on physiological and pathological conditions. Therefore, HIF-1, as a hypoxia-inducible factor in hypoxic conditions, plays an essential role in the adaptation of cells and organs to changes related to the presence of oxygen.

Trichostatin A enhances estrogen receptor-alpha repression in MCF-7 breast cancer cells under hypoxia

International Nuclear Information System (INIS)

Noh, Hyunggyun; Park, Joonwoo; Shim, Myeongguk; Lee, YoungJoo

2016-01-01

Estrogen receptor (ER) is a crucial determinant of resistance to endocrine therapy, which may change during the progression of breast cancer. We previously showed that hypoxia induces ESR1 gene repression and ERα protein degradation via proteasome-mediated pathway in breast cancer cells. HDAC plays important roles in the regulation of histone and non-histone protein post-translational modification. HDAC inhibitors can induce epigenetic changes and have therapeutic potential for targeting various cancers. Trichostatin A exerts potent antitumor activities against breast cancer cells in vitro and in vivo. In this report, we show that TSA augments ESR1 gene repression at the transcriptional level and downregulates ERα protein expression under hypoxic conditions through a proteasome-mediated pathway. TSA-induced estrogen response element-driven reporter activity in the absence of estrogen was synergistically enhanced under hypoxia; however, TSA inhibited cell proliferation under both normoxia and hypoxia. Our data show that the hypoxia-induced repression of ESR1 and degradation of ERα are enhanced by concomitant treatment with TSA. These findings expand our understanding of hormone responsiveness in the tumor microenvironment; however, additional in-depth studies are required to elucidate the detailed mechanisms of TSA-induced ERα regulation under hypoxia. - Highlights: • TSA augments ESR1 gene repression at the transcriptional level under hypoxia. • TSA downregulates ERα protein expression under hypoxia. • TSA-induced ERα regulation under hypoxia is essential for understanding the behavior and progression of breast cancer.

Trichostatin A enhances estrogen receptor-alpha repression in MCF-7 breast cancer cells under hypoxia

Energy Technology Data Exchange (ETDEWEB)

Noh, Hyunggyun; Park, Joonwoo; Shim, Myeongguk; Lee, YoungJoo, E-mail: yjlee@sejong.ac.kr

2016-02-12

Estrogen receptor (ER) is a crucial determinant of resistance to endocrine therapy, which may change during the progression of breast cancer. We previously showed that hypoxia induces ESR1 gene repression and ERα protein degradation via proteasome-mediated pathway in breast cancer cells. HDAC plays important roles in the regulation of histone and non-histone protein post-translational modification. HDAC inhibitors can induce epigenetic changes and have therapeutic potential for targeting various cancers. Trichostatin A exerts potent antitumor activities against breast cancer cells in vitro and in vivo. In this report, we show that TSA augments ESR1 gene repression at the transcriptional level and downregulates ERα protein expression under hypoxic conditions through a proteasome-mediated pathway. TSA-induced estrogen response element-driven reporter activity in the absence of estrogen was synergistically enhanced under hypoxia; however, TSA inhibited cell proliferation under both normoxia and hypoxia. Our data show that the hypoxia-induced repression of ESR1 and degradation of ERα are enhanced by concomitant treatment with TSA. These findings expand our understanding of hormone responsiveness in the tumor microenvironment; however, additional in-depth studies are required to elucidate the detailed mechanisms of TSA-induced ERα regulation under hypoxia. - Highlights: • TSA augments ESR1 gene repression at the transcriptional level under hypoxia. • TSA downregulates ERα protein expression under hypoxia. • TSA-induced ERα regulation under hypoxia is essential for understanding the behavior and progression of breast cancer.

Ageing and cardiorespiratory response to hypoxia.

Science.gov (United States)

Lhuissier, François J; Canouï-Poitrine, Florence; Richalet, Jean-Paul

2012-11-01

The risk of severe altitude-induced diseases is related to ventilatory and cardiac responses to hypoxia and is dependent on sex, age and exercise training status. However, it remains unclear how ageing modifies these physiological adaptations to hypoxia. We assessed the physiological responses to hypoxia with ageing through a cross-sectional 20 year study including 4675 subjects (2789 men, 1886 women; 14-85 years old) and a longitudinal study including 30 subjects explored at a mean 10.4 year interval. The influence of sex, training status and menopause was evaluated. The hypoxia-induced desaturation and the ventilatory and cardiac responses to hypoxia at rest and exercise were measured. In men, ventilatory response to hypoxia increased (P ageing. Cardiac response to hypoxia was blunted with ageing in both sexes (P ageing. These adaptive responses were less pronounced or absent in post-menopausal women (P ageing in men while cardiac response is blunted with ageing in both sexes. Training aggravates desaturation at exercise in hypoxia, improves the ventilatory response and limits the ageing-induced blunting of cardiac response to hypoxia. Training limits the negative effects of menopause in cardiorespiratory adaptations to hypoxia.

Globular Adiponectin Inhibits the Apoptosis of Mesenchymal Stem Cells Induced by Hypoxia and Serum Deprivation via the AdipoR1-Mediated Pathway

OpenAIRE

Xia-Qiu Tian; Yue-Jin Yang; Qing Li; Pei-Sen Huang; Xiang-Dong Li; Chen Jin; Kang Qi; Lei-Pei Jiang; Gui-Hao Chen

2016-01-01

Background/Aims: Poor viability of transplanted mesenchymal stem cells (MSCs) within the ischemic heart limits their therapeutic potential for cardiac repair. Globular adiponectin (gAPN) exerts anti-apoptotic effects on several types of stem cells. Herein, we investigated the effect of gAPN on the MSCs against apoptosis induced by hypoxia and serum deprivation (H/SD). Methods: MSCs exposed to H/SD conditions were treated with different concentrations of gAPN. To identify the main type of rece...

Vagal activity and oxygen saturation response to hypoxia: Effects of aerobic fitness and rating of hypoxia tolerance

Directory of Open Access Journals (Sweden)

Tomáš Macoun

2017-10-01

Full Text Available Background: A reduction in the inspired oxygen fraction (FiO2 induces a decline in arterial oxygen saturation (SpO2 and changes of heart rate variability (HRV. It has been shown that SpO2 and HRV responses to similar levels of acute normobaric hypoxia are inter-individual variable. Variable response may be influenced by normoxia reached maximal oxygen uptake (VO2max value. Objective: The primary aim was to assess HRV and the SpO2 response to hypoxia, and examine the association with normoxic VO2max. Methods: Supine HRV and SpO2 were monitored during normobaric hypoxia (FiO2 = 9.6% for 10 minutes in 28 subjects, aged 23.7 ± 1.7 years. HRV was evaluated by using both spectral and time domain HRV analysis. Low frequency (LF, 0.05-0.15 Hz and high frequency (HF, 0.15-0.50 Hz power together with square root of the mean of the squares of the successive differences (rMSSD were calculated and transformed by natural logarithm (Ln. Based on the SpO2 in hypoxia, subjects were divided into Resistant (RG, SpO2 ≥ 70.9%, n = 14 and Sensitive (SG, SpO2 < 70.9%, n = 14 groups. Perceived hypoxia tolerance was self-scored on a 4-level scale. Results: VO2max was higher in SG (62.4 ± 7.2 ml ⋅ kg-1 ⋅ min-1 compared with RG (55.5 ± 7.1 ml ⋅ kg-1 ⋅ min-1, p = .017, d = 0.97. A significant relationship (r = -.45, p = .017 between hypoxic-normoxic difference in SpO2 and normoxic VO2max level was found. Vagal activity (Ln rMSSD was significantly decreased (SG: p < .001, d = 2.64; RG: p < .001, d = 1.22, while sympathetic activity (Ln LF/HF was relatively increased (p < .001, d = -1.40 in only the SG during hypoxia. Conclusions: Results show that subjects with a higher aerobic capacity exhibited a greater decline in SpO2, accompanied by greater autonomic cardiac disturbances during hypoxia. The SpO2 reduction was associated with perceived hypoxia comfort/discomfort. The hypoxia

Impact of intermittent hypoxia and exercise on blood pressure and metabolic features from obese subjects suffering sleep apnea-hypopnea syndrome.

Science.gov (United States)

González-Muniesa, P; Lopez-Pascual, A; de Andrés, J; Lasa, A; Portillo, M P; Arós, F; Durán, J; Egea, C J; Martinez, J A

2015-09-01

Strategies designed to reduce adiposity and cardiovascular-accompanying manifestations have been based on nutritional interventions conjointly with physical activity programs. The aim of this 13-week study was to investigate the putative benefits associated to hypoxia plus exercise on weight loss and relevant metabolic and cardiorespiratory variables, when prescribed to obese subjects with sleep apnea syndrome following dietary advice. The participants were randomly distributed in the following three groups: control, normoxia, and hypoxia. All the subjects received dietary advice while, additionally, normoxia group was trained under normal oxygen concentration and Hypoxia group under hypoxic conditions. There was a statistically significant decrease in fat-free mass (Kg) and water (%) on the control compared to normoxia group (p hypoxia compared to control group (p hypoxia group showed some specific benefits concerning appetite and cardiometabolic-related measurements as exertion time and diastolic blood pressure, with a therapeutical potential.

Dynamics and distribution of natural and human-caused hypoxia

Science.gov (United States)

Rabalais, N. N.; Díaz, R. J.; Levin, L. A.; Turner, R. E.; Gilbert, D.; Zhang, J.

2010-02-01

Water masses can become undersaturated with oxygen when natural processes alone or in combination with anthropogenic processes produce enough organic carbon that is aerobically decomposed faster than the rate of oxygen re-aeration. The dominant natural processes usually involved are photosynthetic carbon production and microbial respiration. The re-supply rate is indirectly related to its isolation from the surface layer. Hypoxic water masses (hypoxic areas has been exacerbated by any combination of interactions that increase primary production and accumulation of organic carbon leading to increased respiratory demand for oxygen below a seasonal or permanent pycnocline. Nutrient loading is likely to increase further as population growth and resource intensification rises, especially with increased dependency on crops using fertilizers, burning of fossil fuels, urbanization, and waste water generation. It is likely that the occurrence and persistence of hypoxia will be even more widespread and have more impacts than presently observed. Global climate change will further complicate the causative factors in both natural and human-caused hypoxia. The likelihood of strengthened stratification alone, from increased surface water temperature as the global climate warms, is sufficient to worsen hypoxia where it currently exists and facilitate its formation in additional waters. Increased precipitation that increases freshwater discharge and flux of nutrients will result in increased primary production in the receiving waters up to a point. The interplay of increased nutrients and stratification where they occur will aggravate and accelerate hypoxia. Changes in wind fields may expand oxygen minimum zones onto more continental shelf areas. On the other hand, not all regions will experience increased precipitation, some oceanic water temperatures may decrease as currents shift, and frequency and severity of tropical storms may increase and temporarily disrupt hypoxia more

Coastal hypoxia and sediment biogeochemistry

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J. J. Middelburg

2009-07-01

Full Text Available The intensity, duration and frequency of coastal hypoxia (oxygen concentration <63 μM are increasing due to human alteration of coastal ecosystems and changes in oceanographic conditions due to global warming. Here we provide a concise review of the consequences of coastal hypoxia for sediment biogeochemistry. Changes in bottom-water oxygen levels have consequences for early diagenetic pathways (more anaerobic at expense of aerobic pathways, the efficiency of re-oxidation of reduced metabolites and the nature, direction and magnitude of sediment-water exchange fluxes. Hypoxia may also lead to more organic matter accumulation and burial and the organic matter eventually buried is also of higher quality, i.e. less degraded. Bottom-water oxygen levels also affect the organisms involved in organic matter processing with the contribution of metazoans decreasing as oxygen levels drop. Hypoxia has a significant effect on benthic animals with the consequences that ecosystem functions related to macrofauna such as bio-irrigation and bioturbation are significantly affected by hypoxia as well. Since many microbes and microbial-mediated biogeochemical processes depend on animal-induced transport processes (e.g. re-oxidation of particulate reduced sulphur and denitrification, there are indirect hypoxia effects on biogeochemistry via the benthos. Severe long-lasting hypoxia and anoxia may result in the accumulation of reduced compounds in sediments and elimination of macrobenthic communities with the consequences that biogeochemical properties during trajectories of decreasing and increasing oxygen may be different (hysteresis with consequences for coastal ecosystem dynamics.

Metabolic Effects of Hypoxia in Colorectal Cancer by 13C NMR Isotopomer Analysis

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Ana M. Abrantes

2014-01-01

Full Text Available 13C NMR isotopomer analysis was used to characterize intermediary metabolism in three colorectal cancer cell lines (WiDr, LS1034, and C2BBe1 and determine the “metabolic remodeling” that occurs under hypoxia. Under normoxia, the three colorectal cancer cell lines present high rates of lactate production and can be seen as “Warburg” like cancer cells independently of substrate availability, since such profile was dominant at both high and low glucose media contents. The LS1034 was the less glycolytic of the three cell lines and was the most affected by the event of hypoxia, raising abruptly glucose consumption and lactate production. The other two colorectal cell lines, WiDr and C2BBe1, adapted better to hypoxia and were able to maintain their oxidative fluxes even at the very low levels of oxygen. These differential metabolic behaviors of the three colorectal cell lines show how important an adequate knowledge of the “metabolic remodeling” that follows a given cancer treatment is towards the correct (redesign of therapeutic strategies against cancer.

Modulation of radioprotective effects of respiratory hypoxia by changing the duration of hypoxia before irradiation and by combining hypoxia and administration of hemopoiesis-stimulating agents

Energy Technology Data Exchange (ETDEWEB)

Vacek, A.; Hofer, M. [Czechoslovak Academy of Sciences, Brno (Czech Republic). Inst. of Biophysics; Tacev, T. [Masaryk Memorial Cancer Inst., Brno (Czechoslovakia)

2001-09-01

Aim: Analysis of radioprotective effect of respiratory hypoxia on hemopoietic tissue and enhancement of this effect by hemopoietic activation. Material and methods: In mice breathing hypoxic gas mixture during total body gamma irradiation the recovery of pluripotent and committed granulocyte-macrophage progenitor cells and animal lethality were determined. Results: In mice forced to breathe 10% O{sub 2} and 8% O{sub 2} during irradiation, the oxygen tension in the spleen decreased to 40% and 20%, respectively, of control values. Hypoxia mitigated the lethal effect of gamma-rays and improved the recovery of hemopoiesis in compartments of pluripotent and committed progenitor cells. Enhancement of the proliferative activity in hemopoietic tissue by a cytokine (rmGM-CSF) or an immunomodulator (dextran sulfate) increased the effect of hypoxic radioprotection, while elimination of proliferative cells by hydroxyurea decreased the radioprotective effect. Adaptation of experimental animals to hypoxic conditions was found to reduce the radioprotective effect without influencing tissue partial oxygen pressure lowered by hypoxic conditions. Conclusion: The data presented confirm the radioprotective effect of 10% and 8% O{sub 2} respiratory hypoxia on hemopoiesis. These findings may represent a way out for further experimental and clinical research aimed at considering differential protection of various tissues by hypoxia. (orig.) [German] Ziel: Analyse von radioprotektiver Wirkung der respiratorischen Hypoxie auf das haematopoetische Gewebe und Verstaerkung dieses Effekts durch Aktivierung der Haematopoese. Material und Methode: Es wurden bei Maeusen, die 10%igen und 8%igen Sauerstoff waehrend der Bestrahlung geatmet haben, die Erholung von pluripotenten und unipotenten Progenitorzellen und das Ueberleben nach einer letalen Strahlendosis untersucht. Ergebnisse: Bei Maeusen, die 10% und 8% Sauerstoff waehrend der Strahlentherapie geatmet haben, sank der Sauerstoffpartialdruck

Dynamics and distribution of natural and human-caused hypoxia

Directory of Open Access Journals (Sweden)

N. N. Rabalais

2010-02-01

Full Text Available Water masses can become undersaturated with oxygen when natural processes alone or in combination with anthropogenic processes produce enough organic carbon that is aerobically decomposed faster than the rate of oxygen re-aeration. The dominant natural processes usually involved are photosynthetic carbon production and microbial respiration. The re-supply rate is indirectly related to its isolation from the surface layer. Hypoxic water masses (<2 mg L⁻¹, or approximately 30% saturation can form, therefore, under "natural" conditions, and are more likely to occur in marine systems when the water residence time is extended, water exchange and ventilation are minimal, stratification occurs, and where carbon production and export to the bottom layer are relatively high. Hypoxia has occurred through geological time and naturally occurs in oxygen minimum zones, deep basins, eastern boundary upwelling systems, and fjords.

Hypoxia development and continuation in many areas of the world's coastal ocean is accelerated by human activities, especially where nutrient loading increased in the Anthropocene. This higher loading set in motion a cascading set of events related to eutrophication. The formation of hypoxic areas has been exacerbated by any combination of interactions that increase primary production and accumulation of organic carbon leading to increased respiratory demand for oxygen below a seasonal or permanent pycnocline. Nutrient loading is likely to increase further as population growth and resource intensification rises, especially with increased dependency on crops using fertilizers, burning of fossil fuels, urbanization, and waste water generation. It is likely that the occurrence and persistence of hypoxia will be even more widespread and have more impacts than presently observed.

Global climate change will further complicate the causative factors in both natural and human-caused hypoxia. The likelihood of

[Development of Holistic Cancer Treatment Centering Cancer Patients - From the Standpoint of Hypoxia and Hedgehog Signaling].

Science.gov (United States)

Onishi, Hideya; Ogino, Toshitatsu; Morisaki, Takashi; Katano, Mitsuo

2017-11-01

Recently, hypoxia that is one of cancer microenvironments, takes much attention. Because circumstance that we usually perform experiment is 20% O2 condition, it is likely that different signaling pathways may be activated in vivo cancer. We focused Hedgehog(Hh)signaling as one of activated pathways under hypoxia. It has been shown that Hh signaling is activated under hypoxia, followed by inducing malignant phenotypes in pancreatic cancer. Therefore, Hh signaling inhibitor should elicit anti-tumor effect. However, if we consider "whole-person therapy" we should confirm how Hh signaling affects the function of immune cells. In the present study, we describe hypoxia/Hh signaling/functions of cancer cells and immune cells focusing our previous results.

CD133 Modulate HIF-1α Expression under Hypoxia in EMT Phenotype Pancreatic Cancer Stem-Like Cells

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Koki Maeda

2016-06-01

Full Text Available Although CD133 is a known representative cancer stem cell marker, its function in tumor aggressiveness under hypoxia is not fully known. The aim of this study is to demonstrate that CD133 regulates hypoxia inducible factor (HIF-1α expression with tumor migration. The CD133+ pancreatic cancer cell line, Capan1M9, was compared with the CD133− cell line, shCD133M9, under hypoxia. HIF-1α expression levels were compared by Western blot, HIF-1α nucleus translocation assay and real-time (RT-PCR. The hypoxia responsive element (HRE was observed by luciferase assay. The migration ability was analyzed by migration and wound healing assays. Epithelial mesenchymal transition (EMT related genes were analyzed by real-time RT-PCR. HIF-1α was highly expressed in Capan1M9 compared to shCD133M9 under hypoxia because of the high activation of HRE. Furthermore, the migration ability of Capan1M9 was higher than that of shCD133M9 under hypoxia, suggesting higher expression of EMT related genes in Capan1M9 compared to shCD133M9. Conclusion: HIF-1α expression under hypoxia in CD133+ pancreatic cancer cells correlated with tumor cell migration through EMT gene expression. Understanding the function of CD133 in cancer aggressiveness provides a novel therapeutic approach to eradicate pancreatic cancer stem cells.

Hypoxia-Induced Autophagy Is Mediated through Hypoxia-Inducible Factor Induction of BNIP3 and BNIP3L via Their BH3 Domains▿ †

OpenAIRE

Bellot, Grégory; Garcia-Medina, Raquel; Gounon, Pierre; Chiche, Johanna; Roux, Danièle; Pouysségur, Jacques; Mazure, Nathalie M.

2009-01-01

While hypoxia-inducible factor (HIF) is a major actor in the cell survival response to hypoxia, HIF also is associated with cell death. Several studies implicate the HIF-induced putative BH3-only proapoptotic genes bnip3 and bnip3l in hypoxia-mediated cell death. We, like others, do not support this assertion. Here, we clearly demonstrate that the hypoxic microenvironment contributes to survival rather than cell death by inducing autophagy. The ablation of Beclin1, a major actor of autophagy,...

Mitochondrial Respiration in Insulin-Producing β-Cells: General Characteristics and Adaptive Effects of Hypoxia.

Science.gov (United States)

Hals, Ingrid K; Bruerberg, Simon Gustafson; Ma, Zuheng; Scholz, Hanne; Björklund, Anneli; Grill, Valdemar

2015-01-01

To provide novel insights on mitochondrial respiration in β-cells and the adaptive effects of hypoxia. Insulin-producing INS-1 832/13 cells were exposed to 18 hours of hypoxia followed by 20-22 hours re-oxygenation. Mitochondrial respiration was measured by high-resolution respirometry in both intact and permeabilized cells, in the latter after establishing three functional substrate-uncoupler-inhibitor titration (SUIT) protocols. Concomitant measurements included proteins of mitochondrial complexes (Western blotting), ATP and insulin secretion. Intact cells exhibited a high degree of intrinsic uncoupling, comprising about 50% of oxygen consumption in the basal respiratory state. Hypoxia followed by re-oxygenation increased maximal overall respiration. Exploratory experiments in peremabilized cells could not show induction of respiration by malate or pyruvate as reducing substrates, thus glutamate and succinate were used as mitochondrial substrates in SUIT protocols. Permeabilized cells displayed a high capacity for oxidative phosphorylation for both complex I- and II-linked substrates in relation to maximum capacity of electron transfer. Previous hypoxia decreased phosphorylation control of complex I-linked respiration, but not in complex II-linked respiration. Coupling control ratios showed increased coupling efficiency for both complex I- and II-linked substrates in hypoxia-exposed cells. Respiratory rates overall were increased. Also previous hypoxia increased proteins of mitochondrial complexes I and II (Western blotting) in INS-1 cells as well as in rat and human islets. Mitochondrial effects were accompanied by unchanged levels of ATP, increased basal and preserved glucose-induced insulin secretion. Exposure of INS-1 832/13 cells to hypoxia, followed by a re-oxygenation period increases substrate-stimulated respiratory capacity and coupling efficiency. Such effects are accompanied by up-regulation of mitochondrial complexes also in pancreatic islets

Hypoxia modulates the differentiation potential of stem cells of the apical papilla.

Science.gov (United States)

Vanacker, Julie; Viswanath, Aiswarya; De Berdt, Pauline; Everard, Amandine; Cani, Patrice D; Bouzin, Caroline; Feron, Olivier; Diogenes, Anibal; Leprince, Julian G; des Rieux, Anne

2014-09-01

Stem cells from the apical papilla (SCAP) are a population of mesenchymal stem cells likely involved in regenerative endodontic procedures and have potential use as therapeutic agents in other tissues. In these situations, SCAP are exposed to hypoxic conditions either within a root canal devoid of an adequate blood supply or in a scaffold material immediately after implantation. However, the effect of hypoxia on SCAP proliferation and differentiation is largely unknown. Therefore, the objective of this study was to evaluate the effect of hypoxia on the fate of SCAP. SCAP were cultured under normoxia (21% O2) or hypoxia (1% O2) in basal or differentiation media. Cellular proliferation, gene expression, differentiation, and protein secretion were analyzed by live imaging, quantitative reverse-transcriptase polymerase chain reaction, cellular staining, and enzyme-linked immunosorbent assay, respectively. Hypoxia had no effect on SCAP proliferation, but it evoked the up-regulation of genes specific for osteogenic differentiation (runt-related transcription factor 2, alkaline phosphatase, and transforming growth factor-β1), neuronal differentiation ( 2'-3'-cyclic nucleotide 3' phosphodiesterase, SNAIL, neuronspecific enolase, glial cell-derived neurotrophic factor and neurotrophin 3), and angiogenesis (vascular endothelial growth factor A and B). Hypoxia also increased the sustained production of VEGFa by SCAP. Moreover, hypoxia augmented the neuronal differentiation of SCAP in the presence of differentiation exogenous factors as detected by the up-regulation of NSE, VEGFB, and GDNF and the expression of neuronal markers (PanF and NeuN). This study shows that hypoxia induces spontaneous differentiation of SCAP into osteogenic and neurogenic lineages while maintaining the release of the proangiogenic factor VEGFa. This highlights the potential of SCAP to promote pulp-dentin regeneration. Moreover, SCAP may represent potential therapeutic agents for neurodegenerative

Effect of perioperative fetal intrauterine hypoxia on maternal oxidative stress injury after cesarean section

Directory of Open Access Journals (Sweden)

Xue-Hong Zou

2017-03-01

Full Text Available Objective: To study the effect of perioperative fetal intrauterine hypoxia on maternal oxidative stress injury after cesarean section. Methods: 37 puerperae receiving cesarean section for fetal intrauterine hypoxia between May 2014 and December 2016 were selected as hypoxia group and 40 puerperae receiving cesarean section during the same period and without complications during pregnancy or fetal intrauterine hypoxia were selected as control group. Umbilical arterial blood was collected after delivery of placenta for blood gas analysis, and the placenta tissue and serum samples were collected to test the content of oxidative stress products and antioxidants. Results: Umbilical arterial blood gas analysis parameters pH value as well as PO2, HCO3 - and BE content of hypoxia group were significantly lower than those of control group (P＜0.05; NADPH, reactive oxide species (ROS and reactive nitrogen species (RNS content in placenta tissue of hypoxia group were significantly higher than those of control group (P ＜0.05 while glutathione S-transferase (GST, glutathione peroxidase (GPx, superoxide dismutase (SOD, Trx, vitamin C (VitC, VitE and coenzyme Q10 (CoQ10 content were significantly lower than those of control group (P＜0.05; serum malondialdehyde (MDA and 8-iso-prostaglandin F2α (8-iso-PGF2α content of hypoxia group were significantly higher than those of control group (P＜0.05. Conclusions: Perioperative fetal intrauterine hypoxia can lead to maternal oxidative stress injury after cesarean section and increase the generation of free radicals and the consumption of antioxidants.

Hypoxia training: symptom replication in experienced military aircrew.

Science.gov (United States)

Johnston, Ben J; Iremonger, Gareth S; Hunt, Sheena; Beattie, Elizabeth

2012-10-01

Military aircrew are trained to recognize the signs and symptoms of hypoxia in a safe environment using a variety of methods to simulate altitude. In order to investigate the effectiveness of hypoxia training, this study compared the recall of hypoxia symptoms in military aircrew between two consecutive hypobaric chamber hypoxia training sessions conducted, on average, 4.5 yr apart. Previously trained subjects completed a questionnaire immediately before and after they underwent refresher hypoxia training and recorded the occurrence, order, and severity of symptoms experienced. Responses from refresher training were compared with their recall of symptoms experienced during previous training. There was no difference in the recall of most hypoxia symptoms between training sessions. Slurred speech was recalled more frequently from previous training compared to refresher training (14 vs. 4 subjects), whereas hot/cold flushes were recalled less frequently from previous training compared to refresher training (5 vs. 17 subjects). There was a statistically significant difference in overall hypoxia score (10.3 vs. 8.3), suggesting that from memory subjects may underestimate the level of hypoxia experienced in previous training. A high level of similarity between the recall of previously experienced hypoxia symptoms and recent experience supports the effectiveness of hypoxia training. These results replicate the finding of a 'hypoxia signature' reported by a previous study. Small differences in the recall of some symptoms and in overall hypoxia score highlight the importance of drawing attention to the more subtle symptoms of early hypoxia, and of using training techniques which optimize aircrew recall.

Hepcidin: A Critical Regulator of Iron Metabolism during Hypoxia

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Korry J. Hintze

2011-01-01

Full Text Available Iron status affects cognitive and physical performance in humans. Recent evidence indicates that iron balance is a tightly regulated process affected by a series of factors other than diet, to include hypoxia. Hypoxia has profound effects on iron absorption and results in increased iron acquisition and erythropoiesis when humans move from sea level to altitude. The effects of hypoxia on iron balance have been attributed to hepcidin, a central regulator of iron homeostasis. This paper will focus on the molecular mechanisms by which hypoxia affects hepcidin expression, to include a review of the hypoxia inducible factor (HIF/hypoxia response element (HRE system, as well as recent evidence indicating that localized adipose hypoxia due to obesity may affect hepcidin signaling and organismal iron metabolism.

Hypoxia, Oxidative Stress and Fat

Directory of Open Access Journals (Sweden)

Nikolaus Netzer

2015-06-01

Full Text Available Metabolic disturbances in white adipose tissue in obese individuals contribute to the pathogenesis of insulin resistance and the development of type 2 diabetes mellitus. Impaired insulin action in adipocytes is associated with elevated lipolysis and increased free fatty acids leading to ectopic fat deposition in liver and skeletal muscle. Chronic adipose tissue hypoxia has been suggested to be part of pathomechanisms causing dysfunction of adipocytes. Hypoxia can provoke oxidative stress in human and animal adipocytes and reduce the production of beneficial adipokines, such as adiponectin. However, time-dose responses to hypoxia relativize the effects of hypoxic stress. Long-term exposure of fat cells to hypoxia can lead to the production of beneficial substances such as leptin. Knowledge of time-dose responses of hypoxia on white adipose tissue and the time course of generation of oxidative stress in adipocytes is still scarce. This paper reviews the potential links between adipose tissue hypoxia, oxidative stress, mitochondrial dysfunction, and low-grade inflammation caused by adipocyte hypertrophy, macrophage infiltration and production of inflammatory mediators.

Exertional dyspnoea in obesity

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Vipa Bernhardt

2016-12-01

Full Text Available The purpose of cardiopulmonary exercise testing (CPET in the obese person, as in any cardiopulmonary exercise test, is to determine the patient's exercise tolerance, and to help identify and/or distinguish between the various physiological factors that could contribute to exercise intolerance. Unexplained dyspnoea on exertion is a common reason for CPET, but it is an extremely complex symptom to explain. Sometimes obesity is the simple answer by elimination of other possibilities. Thus, distinguishing among multiple clinical causes for exertional dyspnoea depends on the ability to eliminate possibilities while recognising response patterns that are unique to the obese patient. This includes the otherwise healthy obese patient, as well as the obese patient with potentially multiple cardiopulmonary limitations. Despite obvious limitations in lung function, metabolic disease and/or cardiovascular dysfunction, obesity may be the most likely reason for exertional dyspnoea. In this article, we will review the more common cardiopulmonary responses to exercise in the otherwise healthy obese adult with special emphasis on dyspnoea on exertion.

Ecosystem impacts of hypoxia: thresholds of hypoxia and pathways to recovery

International Nuclear Information System (INIS)

Steckbauer, A; Duarte, C M; Vaquer-Sunyer, R; Carstensen, J; Conley, D J

2011-01-01

Coastal hypoxia is increasing in the global coastal zone, where it is recognized as a major threat to biota. Managerial efforts to prevent hypoxia and achieve recovery of ecosystems already affected by hypoxia are largely based on nutrient reduction plans. However, these managerial efforts need to be informed by predictions on the thresholds of hypoxia (i.e. the oxygen levels required to conserve biodiversity) as well as the timescales for the recovery of ecosystems already affected by hypoxia. The thresholds for hypoxia in coastal ecosystems are higher than previously thought and are not static, but regulated by local and global processes, being particularly sensitive to warming. The examination of recovery processes in a number of coastal areas managed for reducing nutrient inputs and, thus, hypoxia (Northern Adriatic; Black Sea; Baltic Sea; Delaware Bay; and Danish Coastal Areas) reveals that recovery timescales following the return to normal oxygen conditions are much longer than those of loss following the onset of hypoxia, and typically involve decadal timescales. The extended lag time for ecosystem recovery from hypoxia results in non-linear pathways of recovery due to hysteresis and the shift in baselines, affecting the oxygen thresholds for hypoxia through time.

Combined fetal inflammation and postnatal hypoxia causes myelin deficits and autism-like behavior in a rat model of diffuse white matter injury.

Science.gov (United States)

van Tilborg, Erik; Achterberg, E J Marijke; van Kammen, Caren M; van der Toorn, Annette; Groenendaal, Floris; Dijkhuizen, Rick M; Heijnen, Cobi J; Vanderschuren, Louk J M J; Benders, Manon N J L; Nijboer, Cora H A

2018-01-01

Diffuse white matter injury (WMI) is a serious problem in extremely preterm infants, and is associated with adverse neurodevelopmental outcome, including cognitive impairments and an increased risk of autism-spectrum disorders. Important risk factors include fetal or perinatal inflammatory insults and fluctuating cerebral oxygenation. However, the exact mechanisms underlying diffuse WMI are not fully understood and no treatment options are currently available. The use of clinically relevant animal models is crucial to advance knowledge on the pathophysiology of diffuse WMI, allowing the definition of novel therapeutic targets. In the present study, we developed a multiple-hit animal model of diffuse WMI by combining fetal inflammation and postnatal hypoxia in rats. We characterized the effects on white matter development and functional outcome by immunohistochemistry, MRI and behavioral paradigms. Combined fetal inflammation and postnatal hypoxia resulted in delayed cortical myelination, microglia activation and astrogliosis at P18, together with long-term changes in oligodendrocyte maturation as observed in 10 week old animals. Furthermore, rats with WMI showed impaired motor performance, increased anxiety and signs of autism-like behavior, i.e. reduced social play behavior and increased repetitive grooming. In conclusion, the combination of fetal inflammation and postnatal hypoxia in rats induces a pattern of brain injury and functional impairments that closely resembles the clinical situation of diffuse WMI. This animal model provides the opportunity to elucidate pathophysiological mechanisms underlying WMI, and can be used to develop novel treatment options for diffuse WMI in preterm infants. © 2017 The Authors GLIA Published by Wiley Periodicals, Inc.

Effects of ration size and hypoxia on specific dynamic action in the cod

DEFF Research Database (Denmark)

Jordan, Anders D; Steffensen, John F

2007-01-01

We present the first data on the effect of hypoxia on the specific dynamic action (SDA) in a teleost fish. Juvenile cod (Gadus morhua) were fed meals of 2.5% and 5% of their wet body mass (BM) in normoxia (19.8 kPa Po(2)) and 5% BM in hypoxia (6.3 kPa Po(2)). Reduced O(2) availability depressed...... the postprandial peaks of oxygen consumption, and to compensate for this, the total SDA duration lasted 212.0+/-20 h in hypoxia, compared with 95.1+/-25 h in normoxia. The percentage of energy associated with the meal digestion and assimilation (SDA coefficient) was equivalent between the different feeding rations...

Seasonal and interannual effects of hypoxia on fish habitat quality in central Lake Erie

Science.gov (United States)

Arend, Kristin K.; Beletsky, Dmitry; DePinto, Joseph; Ludsin, Stuart A.; Roberts, James J.; Rucinski, Daniel K.; Scavia, Donald; Schwab, David J.; Höök, Tomas O.

2011-01-01

1. Hypoxia occurs seasonally in many stratified coastal marine and freshwater ecosystems when bottom dissolved oxygen (DO) concentrations are depleted below 2–3 mg O2 L-1. 2. We evaluated the effects of hypoxia on fish habitat quality in the central basin of Lake Erie from 1987 to 2005, using bioenergetic growth rate potential (GRP) as a proxy for habitat quality. We compared the effect of hypoxia on habitat quality of (i) rainbow smelt, Osmerus mordax mordax Mitchill (young-of-year, YOY, and adult), a cold-water planktivore, (ii) emerald shiner, Notropis atherinoides Rafinesque (adult), a warm-water planktivore, (iii) yellow perch, Perca flavescens Mitchill (YOY and adult), a cool-water benthopelagic omnivore and (iv) round goby Neogobius melanostomus Pallas (adult) a eurythermal benthivore. Annual thermal and DO profiles were generated from 1D thermal and DO hydrodynamics models developed for Lake Erie’s central basin. 3. Hypoxia occurred annually, typically from mid-July to mid-October, which spatially and temporally overlaps with otherwise high benthic habitat quality. Hypoxia reduced the habitat quality across fish species and life stages, but the magnitude of the reduction varied both among and within species because of the differences in tolerance to low DO levels and warm-water temperatures. 4. Across years, trends in habitat quality mirrored trends in phosphorus concentration and water column oxygen demand in central Lake Erie. The per cent reduction in habitat quality owing to hypoxia was greatest for adult rainbow smelt and round goby (mean: -35%), followed by adult emerald shiner (mean: -12%), YOY rainbow smelt (mean: -10%) and YOY and adult yellow perch (mean: -8.5%). 5. Our results highlight the importance of differential spatiotemporally interactive effects of DO and temperature on relative fish habitat quality and quantity. These effects have the potential to influence the performance of individual fish species as well as population dynamics

Effect of dead space on breathing stability at exercise in hypoxia.

Science.gov (United States)

Hermand, Eric; Lhuissier, François J; Richalet, Jean-Paul

2017-12-01

Recent studies have shown that normal subjects exhibit periodic breathing when submitted to concomitant environmental (hypoxia) and physiological (exercise) stresses. A mathematical model including mass balance equations confirmed the short period of ventilatory oscillations and pointed out an important role of dead space in the genesis of these phenomena. Ten healthy subjects performed mild exercise on a cycloergometer in different conditions: rest/exercise, normoxia/hypoxia and no added dead space/added dead space (aDS). Ventilatory oscillations (V˙E peak power) were augmented by exercise, hypoxia and aDS (Pspace. This underlines opposite effects observed in heart failure patients and normal subjects, in which added dead space drastically reduced periodic breathing and sleep apneas. It also points out that alveolar ventilation remains very close to metabolic needs and is not affected by an added dead space. Clinical Trial reg. n°: NCT02201875. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of microenviroment hypoxia on glioma cells radiosensitivity through cancer stem cell pathway

International Nuclear Information System (INIS)

Tong Liumei; Feng Libo; Lu Xueguan; Chen Liesong; Guo Xinwei; Tian Ye

2010-01-01

Objective: To investigate the effect of microenviroment hypoxia on glioma cells radiosensitivity through cancer stem pathway, and to explore the related mechanism. Methods: Glioma cell lines SHG44 and U251 were cultured in normoxia (20% O 2 ) or continuous hypoxia (1% O 2 ) for 12 and 24 h. The fraction of glioma cells with positive expression of CD133 was assayed by flow cytometry. The radiosensitivity of glioma cells was determined by clonogenic cell assay. Western blotting was used to investigate the expressions of HIF-1 α and its downstream gene Notch 1. Results: The fraction of glioma cells with positive expression of CD133 was higher after hypoxic culture for 12 and 24 h than that of the corresponding cells cultured in normoxia. Compared to the cells cultured in normoxia, SF 2 (survival fraction at 2 Gy) were enhanced significantly in SHG44 and U251 cells cultured in hypoxia for 12 and 24 h. The OER (oxygen-enhancement ratio) of SHG44 cells in hypoxia for 12 and 24 h was 1.54 and 1.38, respectively. The OER of U251 cells was 1.44 and 1.23, respectively. The radiosensitivity of these two cell line was decreased in hypoxia. The protein expressions of HIF-1 α and Notch 1 genes were elevated more significantly for cells cultured in hypoxia for 12 and 24 h than for those in normoxia. Conclusions: Microenviroment hypoxia could increase the radioresistance of glioma cells through enrichment of cancer stem cells, and HIF-1 α-Notch 1 signal pathway may play an important role in this process. (authors)

The protective effect of hypoxia and dithiothreitol on X-ray-induced genetic damage in Arabidopsis

International Nuclear Information System (INIS)

Sree Ramulu, K.; Veen, J.H. van der

1987-01-01

A study was made on the protective effect of hypoxia and dithiothreitol (DTT) on X-ray-induced ovule sterility and embryonic lethality in Arabidopsis. Both hypoxia and DTT gave a pronounced and additive reduction of radiation-induced genetic damage. The reduction was significantly higher for ovule sterility than for embryonic lethals. It is suggested that non-fertilized ovules contain a higher ratio of strand breaks/other damage than embryonic lethals do, for hypoxia and DTT are known specifically to give a reduction of strand breaks. (Auth.)

Regulation of human skeletal muscle perfusion and its heterogeneity during exercise in moderate hypoxia

DEFF Research Database (Denmark)

Heinonen, Ilkka H; Kemppainen, Jukka; Kaskinoro, Kimmo

2010-01-01

, the results show that increased BF during one-leg exercise in moderate hypoxia is confined only to the contracting muscles, and the working muscle hyperemia appears not to be directly mediated by adenosine. Increased flow heterogeneity in noncontracting muscles likely reflects sympathetic nervous constraints...... healthy young men using positron emission tomography during one-leg dynamic knee extension exercise in normoxia and moderate physiological systemic hypoxia (14% O(2) corresponding to approximately 3,400 m of altitude) without and with local adenosine receptor inhibition with femoral artery infusion...... to curtail BF increments in areas other than working skeletal muscles, but this effect is not potentiated in moderate systemic hypoxia during small muscle mass exercise....

Translational control is a major contributor to hypoxia induced gene expression

International Nuclear Information System (INIS)

Beucken, Twan van den; Magagnin, Michael G.; Jutten, Barry; Seigneuric, Renaud; Lambin, Philippe; Koritzinsky, Marianne; Wouters, Bradly G.

2011-01-01

Background and purpose: Hypoxia is a common feature of solid tumors that is associated with an aggressive phenotype, resistance to therapy and poor prognosis. Major contributors to these adverse effects are the transcriptional program activated by the HIF family of transcription factors as well as the translational response mediated by PERK-dependent phosphorylation of eIF2α and inhibition of mTORC1 activity. In this study we determined the relative contribution of both transcriptional and translational responses to changes in hypoxia induced gene expression. Material and methods: Total and efficiently translated (polysomal) mRNA was isolated from DU145 prostate carcinoma cells that were exposed for up to 24 h of hypoxia ( 2 ). Changes in transcription and translation were assessed using affymetrix microarray technology. Results: Our data reveal an unexpectedly large contribution of translation control on both induced and repressed gene expression at all hypoxic time points, particularly during acute hypoxia (2-4 h). Gene ontology analysis revealed that gene classes like transcription and signal transduction are stimulated by translational control whereas expression of genes involved in cell growth and protein metabolism are repressed during hypoxic conditions by translational control. Conclusions: Our data indicate that translation influences gene expression during hypoxia on a scale comparable to that of transcription.

Symbiodinium mitigate the combined effects of hypoxia and acidification on a noncalcifying cnidarian

KAUST Repository

Klein, Shannon G.

2017-04-08

Anthropogenic nutrient inputs enhance microbial respiration within many coastal ecosystems, driving concurrent hypoxia and acidification. During photosynthesis, Symbiodinium spp., the microalgal endosymbionts of cnidarians and other marine phyla, produce O and assimilate CO and thus potentially mitigate the exposure of the host to these stresses. However, such a role for Symbiodinium remains untested for noncalcifying cnidarians. We therefore contrasted the fitness of symbiotic and aposymbiotic polyps of a model host jellyfish (Cassiopea sp.) under reduced O (~2.09 mg/L) and pH (~ 7.63) scenarios in a full-factorial experiment. Host fitness was characterized as asexual reproduction and their ability to regulate internal pH and Symbiodinium performance characterized by maximum photochemical efficiency, chla content and cell density. Acidification alone resulted in 58% more asexual reproduction of symbiotic polyps than aposymbiotic polyps (and enhanced Symbiodinium cell density) suggesting Cassiopea sp. fitness was enhanced by CO-stimulated Symbiodinium photosynthetic activity. Indeed, greater CO drawdown (elevated pH) was observed within host tissues of symbiotic polyps under acidification regardless of O conditions. Hypoxia alone produced 22% fewer polyps than ambient conditions regardless of acidification and symbiont status, suggesting Symbiodinium photosynthetic activity did not mitigate its effects. Combined hypoxia and acidification, however, produced similar numbers of symbiotic polyps compared with aposymbiotic kept under ambient conditions, demonstrating that the presence of Symbiodinium was key for mitigating the combined effects of hypoxia and acidification on asexual reproduction. We hypothesize that this mitigation occurred because of reduced photorespiration under elevated CO conditions where increased net O production ameliorates oxygen debt. We show that Symbiodinium play an important role in facilitating enhanced fitness of Cassiopea sp. polyps, and

Overexpression of Hypoxia-Inducible Factor-1α Exacerbates Endothelial Barrier Dysfunction Induced by Hypoxia

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Pei Wang

2013-09-01

Full Text Available Background/Aims: The mechanisms involved in endothelial barrier dysfunction induced by hypoxia are incompletely understood. There is debate about the role of hypoxia-inducible factor-1α (HIF-1α in endothelial barrier disruption. The aim of this study was to investigate the effect of genetic overexpression of HIF-1α on barrier function and the underlying mechanisms in hypoxic endothelial cells. Methods: The plasmid pcDNA3.1/V5-His-HIF-1α was stably transfected into human endothelial cells. The cells were exposed to normoxia or hypoxia. The mRNA and protein expressions of HIF-1α were detected by RT-PCR and Western blot respectively. The barrier function was assessed by measuring the transendothelial electrical resistance (TER. The Western blot analysis was used to determine the protein expression of glucose transporter-1 (GLUT-1, zonular occludens-1 (ZO-1, occludin, and myosin light chain kinase (MLCK in endothelial cells. The mRNA expression of proinflammatory cytokines was detected by qRT-PCR. Results: Genetic overexpression of HIF-1α significantly increased the mRNA and protein expression of HIF-1α in endothelial cells. The overexpression of HIF-1α enhanced the hypoxia-induced increase of HIF-1α and GLUT-1 protein expression. HIF-1α overexpression not only exacerbated hypoxia-induced endothelial barrier dysfunction but also augmented hypoxia-induced up-regulation of MLCK protein expression. HIF-1α overexpression also enhanced IL-1β, IL-6 and TNF-α mRNA expression. Conclusion: We provide evidence that genetic overexpression of HIF-1α aggravates the hypoxia-induced endothelial barrier dysfunction via enhancing the up-regulation of MLCK protein expression caused by hypoxia, suggesting a potential role for HIF-1α in the pathogenesis of endothelial barrier dysfunction in hypoxia.

The Role of Bystander Effects in the Antitumor Activity of the Hypoxia-Activated Prodrug PR-104

Science.gov (United States)

Foehrenbacher, Annika; Patel, Kashyap; Abbattista, Maria R.; Guise, Chris P.; Secomb, Timothy W.; Wilson, William R.; Hicks, Kevin O.

2013-01-01

Activation of prodrugs in tumors (e.g., by bioreduction in hypoxic zones) has the potential to generate active metabolites that can diffuse within the tumor microenvironment. Such “bystander effects” may offset spatial heterogeneity in prodrug activation but the relative importance of this effect is not understood. Here, we quantify the contribution of bystander effects to antitumor activity for the first time, by developing a spatially resolved pharmacokinetic/pharmacodynamic (SR-PK/PD) model for PR-104, a phosphate ester pre-prodrug that is converted systemically to the hypoxia-activated prodrug PR-104A. Using Green’s function methods we calculated concentrations of oxygen, PR-104A and its active metabolites, and resultant cell killing, at each point of a mapped three-dimensional tumor microregion. Model parameters were determined in vitro, using single cell suspensions to determine relationships between PR-104A metabolism and clonogenic cell killing, and multicellular layer (MCL) cultures to measure tissue diffusion coefficients. LC-MS/MS detection of active metabolites in the extracellular medium following exposure of anoxic single cell suspensions and MCLs to PR-104A confirmed that metabolites can diffuse out of cells and through a tissue-like environment. The SR-PK/PD model estimated that bystander effects contribute 30 and 50% of PR-104 activity in SiHa and HCT116 tumors, respectively. Testing the model by modulating PR-104A-activating reductases and hypoxia in tumor xenografts showed overall clonogenic killing broadly consistent with model predictions. Overall, our data suggest that bystander effects are important in PR-104 antitumor activity, although their reach may be limited by macroregional heterogeneity in hypoxia and reductase expression in tumors. The reported computational and experimental techniques are broadly applicable to all targeted anticancer prodrugs and could be used to identify strategies for rational prodrug optimization. PMID

Effects of cadmium on hypoxia-induced expression of hemoglobin and erythropoietin in larval sheepshead minnow, Cyprinodon variegatus

Energy Technology Data Exchange (ETDEWEB)

Dangre, A.J.; Manning, S. [Department of Coastal Sciences, University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS 39564 (United States); Brouwer, M., E-mail: marius.brouwer@usm.edu [Department of Coastal Sciences, University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS 39564 (United States)

2010-08-15

Hypoxia and toxic metals are two common stressors found in the estuarine environment. To date little information is available on the combined effects of these stressors on early larval development in fish. We investigated the effect of cadmium and hypoxia exposure alone as well in combination on larval Cyprinodon variegatus. The LC{sub 10} for cadmium was determined to be 0.3 ppm in a 96 h acute exposure. This concentration was used in all studies. Cadmium in larvae increased significantly with exposure time (1, 3, 5 and 7 days post-hatch). The increase was proportional to body weight and not affected by hypoxia. Cadmium responsive genes were identified by suppression subtractive hybridization (SSH) in Cyprinodonvariegatus larvae after exposure to cadmium for 1, 3, 5 and 7 days. We obtained over 700 sequences from the cadmium cDNA library. Blast search of ESTs suggested that cadmium modulates multiple physiological processes. Pertinent to this study, cadmium was found to down-regulate both embryonic {alpha} and {beta} globin, which are expressed in erythrocytes generated during the first, or primitive, wave of erythropoiesis in teleosts. Hemoglobin (Hb) and erythropoietin (Epo) (the hormone that promotes red blood cell production) are known hypoxia-inducible genes. To explore the possibility that cadmium might offset the hypoxia-induced expression of Hb and Epo, we investigated the expression of both genes following hypoxia, cadmium and combined exposures for 1, 3, 5 and 7 days post-hatch. Since Epo had not yet been identified in C. variegatus we first successfully cloned a partial coding sequence of the C. variegatus hormone. Subsequent studies revealed that expression levels of Hb and Epo remained unchanged in the normoxic controls during the time course of the study. Hypoxia increased Epo expression relative to normoxic controls, on days 3, 5 and 7, while cadmium in hypoxia inhibited the increase. Only the changes on days 5 and 7 were statistically significant

[Damage effects of chronic hypoxia on medulla oblongata associated with oxidative stress and cell apoptosis].

Science.gov (United States)

Hou, Xuefei; Ding, Yan; Nie, Zheng; Li, Hui; Tang, Yuhong; Zhou, Hua; Chen, Li; Zheng, Yu

2012-08-01

The aim of this study is to study the damage effects of chronic hypoxia on medulla oblongata and to explore whether the damage is associated with oxidative stress and cell apoptosis. Adult male SD rats were randomly divided into two groups: control group and chronic hypoxia group. Medulla oblongata was obtained for the following methods of analyses. Nissl's staining was used to examine the Niss bodies of neurons in medullary respiratory related nuclei, biochemistry methods were utilized to examine oxidant stress damage induced by chronic hypoxia on medulla oblongata through measuring malondialdehyde (MDA) content and superoxide dismutase (SOD) activity, and RT-PCR technique was used to study the influence of apoptosis induced by chronic hypoxia on medulla oblongata through analyzing the levels of Bax mRNA and Bcl-2 mRNA. The results showed the optical densities of Nissl's staining in pre-BötC, NA, NTS, FN, and 12N were significantly decreased in chronic hypoxia group in comparison with that in control group (P 0.05). Bax mRNA expression had no obvious change and Bcl-2 mRNA expression significantly decreased in chronic hypoxia group in comparison with that in control group (P < 0.05). The results suggest that chronic hypoxia could bring about serious damage to medullary respiratory centers through aggravating oxidative stress and increasing cell apoptosis.

Juglans regia Hexane Extract Exerts Antitumor Effect, Apoptosis ...

African Journals Online (AJOL)

Original Research Article. Juglans regia Hexane Extract Exerts Antitumor Effect,. Apoptosis Induction and Cell Circle Arrest in Prostate. Cancer Cells In vitro. Wei Li1, De-Yuan Li2*, ... composition of walnut is juglone (5-hydroxy-1, 4- naphthoquinone), the .... extract was confirmed by studying apoptotic body formation using ...

Screening of hypoxia-inducible genes in sporadic ALS.

LENUS (Irish Health Repository)

Cronin, Simon

2008-10-01

Genetic variations in two hypoxia-inducible angiogenic genes, VEGF and ANG, have been linked with sporadic amyotrophic lateral sclerosis (SALS). Common variations in these genes may reduce the levels or functioning of their products. VEGF and ANG belong to a larger group of angiogenic genes that are up-regulated under hypoxic conditions. We hypothesized that common genetic variation across other members of this group may also predispose to sporadic ALS. To screen other hypoxia-inducible angiogenic genes for association with SALS, we selected 112 tagging single nucleotide polymorphisms (tgSNPs) that captured the common genetic variation across 16 VEGF-like and eight ANG-like hypoxia-inducible genes. Screening for association was performed in 270 Irish individuals with typical SALS and 272 ethnically matched unrelated controls. SNPs showing association in the Irish phase were genotyped in a replication sample of 281 Swedish sporadic ALS patients and 286 Swedish controls. Seven markers showed association in the Irish. The one modest replication signal observed in the Swedish replication sample, at rs3801158 in the gene inhibin beta A, was for the opposite allele vs. the Irish cohort. We failed to detect association of common variation across 24 candidate hypoxia-inducible angiogenic genes with SALS.

Prolonged hypoxia increases survival even in Zebrafish (Danio rerio showing cardiac arrhythmia.

Directory of Open Access Journals (Sweden)

Renate Kopp

Full Text Available Tolerance towards hypoxia is highly pronounced in zebrafish. In this study even beneficial effects of hypoxia, specifically enhanced survival of zebrafish larvae, could be demonstrated. This effect was actually more pronounced in breakdance mutants, which phenotypically show cardiac arrhythmia. Breakdance mutants (bre are characterized by chronically reduced cardiac output. Despite an about 50% heart rate reduction, they become adults, but survival rate significantly drops to 40%. Normoxic bre animals demonstrate increased hypoxia inducible factor 1 a (Hif-1α expression, which indicates an activated hypoxic signaling pathway. Consequently, cardiovascular acclimation, like cardiac hypertrophy and increased erythrocyte concentration, occurs. Thus, it was hypothesized, that under hypoxic conditions survival might be even more reduced. When bre mutants were exposed to hypoxic conditions, they surprisingly showed higher survival rates than under normoxic conditions and even reached wildtype values. In hypoxic wildtype zebrafish, survival yet exceeded normoxic control values. To specify physiological acclimation, cardiovascular and metabolic parameters were measured before hypoxia started (3 dpf, when the first differences in survival rate occurred (7 dpf and when survival rate plateaued (15 dpf. Hypoxic animals expectedly demonstrated Hif-1α accumulation and consequently enhanced convective oxygen carrying capacity. Moreover, bre animals showed a significantly enhanced heart rate under hypoxic conditions, which reached normoxic wildtype values. This improvement in convective oxygen transport ensured a sufficient oxygen and nutrient supply and was also reflected in the significantly higher mitochondrial activity. The highly optimized energy metabolism observed in hypoxic zebrafish larvae might be decisive for periods of higher energy demand due to organ development, growth and increased activity. However, hypoxia increased survival only during a

Suppression of the expression of hypoxia-inducible factor-1α by RNA interference alleviates hypoxia-induced pulmonary hypertension in adult rats.

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Li, Ying; Shi, Bo; Huang, Liping; Wang, Xin; Yu, Xiaona; Guo, Baosheng; Ren, Weidong

2016-12-01

Hypoxia-inducible factor-1α (HIF-1α) has been implicated in the pathogenesis of hypoxic pulmonary hypertension (PH). However, the potential clinical value of HIF-1α as a therapeutic target in the treatment of PH has not yet been evaluated. In this study, an animal model of hypoxia-induced PH was established by exposing adult rats to 10% O2 for 3 weeks, and the effects of the lentivirus-mediated delivery of HIF-1α short hairpin RNA (shRNA) by intratracheal instillation prior to exposure to hypoxia on the manifestations of hypoxia-induced PH were assessed. The successful delivery of HIF-1α shRNA into the pulmonary arteries effectively suppressed the hypoxia-induced upregulation of HIF-1α, accompanied by the prominent attenuation the symptoms associated with hypoxia-induced PH, including the elevation of pulmonary arterial pressure, hypertrophy and hyperplasia of pulmonary artery smooth muscle cells (PASMCs), as well as the muscularization of pulmonary arterioles. In addition, the knockdown of HIF-1α in cultured rat primary PASMCs significantly inhibited the hypoxia-induced acceleration of the cell cycle and the proliferation of the PASMCs, suggesting that HIF-1α may be a direct mediator of PASMC hyperplasia in hypoxia-induced PH. In conclusion, this study demonstrates the potent suppressive effects of HIF-1α shRNA on hypoxia-induced PH and PASMC hyperplasia, providing evidence for the potential application of HIF-1α shRNA in the treatment of hypoxic PH.

Toll-like receptor 4 mediates microglial activation and production of inflammatory mediators in neonatal rat brain following hypoxia: role of TLR4 in hypoxic microglia

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2013-01-01

Background Hypoxia induces microglial activation which causes damage to the developing brain. Microglia derived inflammatory mediators may contribute to this process. Toll-like receptor 4 (TLR4) has been reported to induce microglial activation and cytokines production in brain injuries; however, its role in hypoxic injury remains uncertain. We investigate here TLR4 expression and its roles in neuroinflammation in neonatal rats following hypoxic injury. Methods One day old Wistar rats were subjected to hypoxia for 2 h. Primary cultured microglia and BV-2 cells were subjected to hypoxia for different durations. TLR4 expression in microglia was determined by RT-PCR, western blot and immunofluorescence staining. Small interfering RNA (siRNA) transfection and antibody neutralization were employed to downregulate TLR4 in BV-2 and primary culture. mRNA and protein expression of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and inducible nitric oxide synthase (iNOS) was assessed. Reactive oxygen species (ROS), nitric oxide (NO) and NF-κB levels were determined by flow cytometry, colorimetric and ELISA assays respectively. Hypoxia-inducible factor-1 alpha (HIF-1α) mRNA and protein expression was quantified and where necessary, the protein expression was depleted by antibody neutralization. In vivo inhibition of TLR4 with CLI-095 injection was carried out followed by investigation of inflammatory mediators expression via double immunofluorescence staining. Results TLR4 immunofluorescence and protein expression in the corpus callosum and cerebellum in neonatal microglia were markedly enhanced post-hypoxia. In vitro, TLR4 protein expression was significantly increased in both primary microglia and BV-2 cells post-hypoxia. TLR4 neutralization in primary cultured microglia attenuated the hypoxia-induced expression of TNF-α, IL-1β and iNOS. siRNA knockdown of TLR4 reduced hypoxia-induced upregulation of TNF-α, IL-1β, iNOS, ROS and NO in BV-2 cells. TLR4

Hif1a inactivation rescues photoreceptor degeneration induced by a chronic hypoxia-like stress.

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Barben, Maya; Ail, Divya; Storti, Federica; Klee, Katrin; Schori, Christian; Samardzija, Marijana; Michalakis, Stylianos; Biel, Martin; Meneau, Isabelle; Blaser, Frank; Barthelmes, Daniel; Grimm, Christian

2018-04-17

Reduced choroidal blood flow and tissue changes in the ageing human eye impair oxygen delivery to photoreceptors and the retinal pigment epithelium. As a consequence, mild but chronic hypoxia may develop and disturb cell metabolism, function and ultimately survival, potentially contributing to retinal pathologies such as age-related macular degeneration (AMD). Here, we show that several hypoxia-inducible genes were expressed at higher levels in the aged human retina suggesting increased activity of hypoxia-inducible transcription factors (HIFs) during the physiological ageing process. To model chronically elevated HIF activity and investigate ensuing consequences for photoreceptors, we generated mice lacking von Hippel Lindau (VHL) protein in rods. This activated HIF transcription factors and led to a slowly progressing retinal degeneration in the ageing mouse retina. Importantly, this process depended mainly on HIF1 with only a minor contribution of HIF2. A gene therapy approach using AAV-mediated RNA interference through an anti-Hif1a shRNA significantly mitigated the degeneration suggesting a potential intervention strategy that may be applicable to human patients.

Inhibition of calcium uptake during hypoxia in developing zebrafish is mediated by hypoxia-inducible factor.

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Kwong, Raymond W M; Kumai, Yusuke; Tzaneva, Velislava; Azzi, Estelle; Hochhold, Nina; Robertson, Cayleih; Pelster, Bernd; Perry, Steve F

2016-12-15

The present study investigated the potential role of hypoxia-inducible factor (HIF) in calcium homeostasis in developing zebrafish (Danio rerio). It was demonstrated that zebrafish raised in hypoxic water (30 mmHg; control, 155 mmHg P O 2 ) until 4 days post-fertilization exhibited a substantial reduction in whole-body Ca 2+ levels and Ca 2+ uptake. Ca 2+ uptake in hypoxia-treated fish did not return to pre-hypoxia (control) levels within 2 h of transfer back to normoxic water. Results from real-time PCR showed that hypoxia decreased the whole-body mRNA expression levels of the epithelial Ca 2+ channel (ecac), but not plasma membrane Ca 2+ -ATPase (pmca2) or Na + /Ca 2+ -exchanger (ncx1b). Whole-mount in situ hybridization revealed that the number of ecac-expressing ionocytes was reduced in fish raised in hypoxic water. These findings suggested that hypoxic treatment suppressed the expression of ecac, thereby reducing Ca 2+ influx. To further evaluate the potential mechanisms for the effects of hypoxia on Ca 2+ regulation, a functional gene knockdown approach was employed to prevent the expression of HIF-1αb during hypoxic treatment. Consistent with a role for HIF-1αb in regulating Ca 2+ balance during hypoxia, the results demonstrated that the reduction of Ca 2+ uptake associated with hypoxic exposure was not observed in fish experiencing HIF-1αb knockdown. Additionally, the effects of hypoxia on reducing the number of ecac-expressing ionocytes was less pronounced in HIF-1αb-deficient fish. Overall, the current study revealed that hypoxic exposure inhibited Ca 2+ uptake in developing zebrafish, probably owing to HIF-1αb-mediated suppression of ecac expression. © 2016. Published by The Company of Biologists Ltd.

Effect of mild intermittent hypoxia on glucose tolerance, muscle morphology and AMPK-PGC-1alpha signaling.

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Chen, Chung-Yu; Tsai, Ying-Lan; Kao, Chung-Lan; Lee, Shin-Da; Wu, Ming-Chieh; Mallikarjuna, K; Liao, Yi-Hung; Ivy, John L; Kuo, Chia-Hua

2010-02-28

The main goal of this study was to investigate the long-term effect of daily 8-hour mild intermittent hypoxia (14-15% O2) on glucose tolerance and muscle morphology of Sprague-Dawley rats. The involvement of AMPK-PGC-1alpha-VEGF signaling pathways in the skeletal muscle was also determined during the first 8 hours of hypoxia. We found that mRNA levels of VEGF and PGC-1alpha were significantly increased above control after 8-h mild hypoxia without a change in AMPK phosphorylation. After 8 weeks of mild intermittent hypoxia treatment, plasma glucose and insulin levels in oral glucose tolerance test (OGTT), epididymal fat mass, and body weight were significantly lower compared to the control group. While soleus muscle weight was not changed, capillary and fiber densities in the hypoxia group were 33% and 35% above the control suggesting reorganization of muscle fibers. In conclusion, our data provide strong evidence that long-term mild intermittent hypoxia decreases the diffusion distance of glucose and insulin across muscle fibers, and decreases adiposity in rats. These changes may account for the improved glucose tolerance observed following the 8-week hypoxia treatment, and provides grounds for investigating the development of a mild non-pharmacological intervention in the treatment of obesity and type 2 diabetes.

Imaging tumor hypoxia: Blood-borne delivery of imaging agents is fundamentally different in hypoxia subtypes

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Peter Vaupel

2014-03-01

Full Text Available Hypoxic tissue subvolumes are a hallmark feature of solid malignant tumors, relevant for cancer therapy and patient outcome because they increase both the intrinsic aggressiveness of tumor cells and their resistance to several commonly used anticancer strategies. Pathogenetic mechanisms leading to hypoxia are diverse, may coexist within the same tumor and are commonly grouped according to the duration of their effects. Chronic hypoxia is mainly caused by diffusion limitations resulting from enlarged intercapillary distances and adverse diffusion geometries and — to a lesser extent — by hypoxemia, compromised perfusion or long-lasting microregional flow stops. Conversely, acute hypoxia preferentially results from transient disruptions in perfusion. While each of these features of the tumor microenvironment can contribute to a critical reduction of oxygen availability, the delivery of imaging agents (as well as nutrients and anticancer agents may be compromised or remain unaffected. Thus, a critical appraisal of the effects of the various mechanisms leading to hypoxia with regard to the blood-borne delivery of imaging agents is necessary to judge their ability to correctly represent the hypoxic phenotype of solid malignancies.

Exercise attenuates intermittent hypoxia-induced cardiac fibrosis associated with sodium-hydrogen exchanger-1 in rats

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Tsung-I Chen

2016-10-01

Full Text Available Purpose: To investigate the role of sodium–hydrogen exchanger-1 (NHE-1 and exercise training on intermittent hypoxia-induced cardiac fibrosis in obstructive sleep apnea (OSA, using an animal model mimicking the intermittent hypoxia of OSA. Methods: Eight-week-old male Sprague–Dawley rats were randomly assigned to control (CON, intermittent hypoxia (IH, exercise (EXE or IH combined with exercise (IHEXE groups. These groups were randomly assigned to subgroups receiving either a vehicle or the NHE-1 inhibitor cariporide. The EXE and IHEXE rats underwent exercise training on an animal treadmill for 10 weeks (5 days/week, 60 minutes/day, 24–30 m/minute, 2–10% grade. The IH and IHEXE rats were exposed to 14 days of IH (30 seconds of hypoxia - nadir of 2-6% O2 - followed by 45 seconds of normoxia for 8 hours/day. At the end of 10 weeks, rats were sacrificed and then hearts were removed to determine the myocardial levels of fibrosis index, oxidative stress, antioxidant capacity and NHE-1 activation. Results: Compared to the CON rats, IH induced higher cardiac fibrosis, lower myocardial catalase and superoxidative dismutase activities, higher myocardial lipid and protein peroxidation and higher NHE-1 activation (p < 0.05 for each, which were all abolished by cariporide. Compared to the IH rats, lower cardiac fibrosis, higher myocardial antioxidant capacity, lower myocardial lipid and protein peroxidation and lower NHE-1 activation were found in the IHEXE rats (p < 0.05 for each. Conclusion: IH-induced cardiac fibrosis was associated with NHE-1 hyperactivity. However, exercise training and cariporide exerted an inhibitory effect to prevent myocardial NHE-1 hyperactivity, which contributed to reduced IH-induced cardiac fibrosis. Therefore, NHE-1 plays a critical role in the effect of exercise on IH-induced increased cardiac fibrosis.

[Role of restricted nitric oxide overproduction in the cardioprotective effect of adaptation to intermittent hypoxia].

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goriacheva, A V; Belkina, L M; Terekhina, O L; Dawney, H F; Mallet, R T; Smirin, B V; Smirnova, E A; Mashina, S Iu; Manukhina, E B

2012-01-01

Adaptation to intermittent normobaric hypoxia is cardioprotective and can stimulate nitric oxide (NO) synthesis. However the role of nitric oxide (NO) in prevention of ischemia-reperfusion (IR) injury of myocardium is controversial. This study was focused on evaluating the effect of adaptation to hypoxia and IR on NO production and development of nitrative stress in the myocardium. Adaptation to hypoxia tended to increase NO production, which was determined by the total level of plasma nitrite and nitrate, and prevented IR-induced NO overproduction. The IR-induced NO overproduction was associated with significant 3-nitrotyrosine (3-NT) accumulation in the left ventricle but not in septum or aorta. In hypoxia-adapted rats, 3-NT after IR was similar to that of control rats without IR. IHC induced marked accumulation of HIF-1alpha in the left ventricle. We suggest that HIF-1alpha contributes to NO-synthase expression during adaptation to hypoxia and thereby facilitates the increase in NO production. NO, in turn, may subsequently prevent NO overproduction during IR by a negative feedback mechanism.

Effects of fitness and self-confidence on time perception during exertion

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2015-09-01

Full Text Available Aims: Human physical and psychological features influence perceptions of the environment during activity. If during exercise an individual over-estimates time, they may interpret this as spending longer than necessary under a potentially aversive state of exertion. This may in turn decrease one’s sense of exercise success and tendency to persevere with exercise. We tested if experimentally manipulating sense of exercise self-efficacy would affect time perception during standardised physical exertion. Method: Exercise Self-Efficacy (ESE of 18 -73 year olds (N=51 was measured before and after an exercise challenge of moderate intensity. Height, weight and body fat composition were measured before participants were randomly allocated to one of three groups. After a 4-minute treadmill fitness test, participants were presented with either bogus feedback about their performance (positive or negative or no feedback (control. Before and during exercise, participants estimated a prescribed 2-minute time interval. Ratings of perceived exertion were also measured periodically. Results: Feedback on performance had no significant effect on time perception, even when controlling for individual exertion level. Reported ESE was also unaffected by whether someone received positive, negative or no feedback. Age was again found to be significantly correlated with VO2max, r(51 = .62, p < .001, but in contrast to prior findings, estimates of general fitness such as VO2max, BMI and waist circumference were unrelated to changes in time perception due to exertion. Conclusions: These findings failed to support prior findings and anecdotal evidence suggesting that exertion might alter one’s perception of time. We also failed to find any support for effects on ESE when participants were given explicit performance feedback. Finally, participants’ physical characteristics appear to be unrelated to time perception whilst exercising at moderate intensity.

Hypoxia targeting copper complexes

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Dearling, J.L.

1998-11-01

The importance and incidence of tumour hypoxia, its measurement and current treatments available, including pharmacological and radiopharmacological methods of targeting hypoxia, are discussed. A variety of in vitro and in vivo methods for imposing hypoxia have been developed and are reviewed. Copper, its chemistry, biochemistry and radiochemistry, the potential for use of copper radionuclides and its use to date in this field is considered with particular reference to the thiosemicarbazones. Their biological activity, metal chelation, in vitro and in vivo studies of their radiocopper complexes and the potential for their use as hypoxia targeting radiopharmaceuticals is described. The reduction of the copper(II) complex to copper(l), its pivotal importance in their biological behaviour, and the potential for manipulation of this to effect hypoxia selectivity are described. An in vitro method for assessing the hypoxia selectivity of radiopharmaceuticals is reported. The rapid deoxygenation and high viability of a mammalian cell culture in this system is discussed and factors which may affect the cellular uptake of a radiopharmaceutical are described. The design, synthesis and complexation with copper and radiocopper of a range of bis(thiosemicarbazones) is reported. Synthesis of these compounds is simple giving high yields of pure products. The characteristics of the radiocopper complexes ( 64 Cu) including lipophilicity and redox activity are reported (reduction potentials in the range -0.314 - -0.590 V). High cellular uptakes of the radiocopper complexes of the ligands, in hypoxic and normoxic EMT6 and CHO320 cells, were observed. Extremes of selectivity are shown ranging from the hypoxia selective 64 Cu(II)ATSM to normoxic cell selective 64 Cu(II)GTS. The selectivities observed are compared with the physico chemical characteristics of the complexes. A good correlation exists between selectivity of the complex and its Cu(II)/Cu(I) reduction potential, with hypoxia

THE EFFECT OF HYPOXIA ON THE MAXIMUM MATABOLIC RATE AND SPECIFIC DYNAMIC ACTION IN ATLANTIC COD Gadus morhua

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Steffensen, John Fleng

2010-01-01

John Fleng Steffensen' and Anders Drud Jordan Aquaculture 2010 - San Diego - Physiological Insights Towards Improving Fish Culture. Hypoxia is an increasing problem in coastal near areas and estuaries. Hypoxia can also be a problem in aquaculture systems with a high degree of recirculating water...... reduced the Scope for Activity by 55 % in nonnoxia. In hypoxia the effect was more pronounced with a 69 % reduction of the scope for activity. In conclusion hypoxia prolong the postabsorptive state of fi sh by limiting the peak metabolic rate, causing that less food is assimilated over a certain period...

Chondroprotective effect of zinc oxide nanoparticles in conjunction with hypoxia on bovine cartilage-matrix synthesis.

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Mirza, Eraj Humayun; Pan-Pan, Chong; Wan Ibrahim, Wan Mohd Azhar Bin; Djordjevic, Ivan; Pingguan-Murphy, Belinda

2015-11-01

Articular cartilage is a tissue specifically adapted to a specific niche with a low oxygen tension (hypoxia), and the presence of such conditions is a key factor in regulating growth and survival of chondrocytes. Zinc deficiency has been linked to cartilage-related disease, and presence of Zinc is known to provide antibacterial benefits, which makes its inclusion attractive in an in vitro system to reduce infection. Inclusion of 1% zinc oxide nanoparticles (ZnONP) in poly octanediol citrate (POC) polymer cultured in hypoxia has not been well determined. In this study we investigated the effects of ZnONP on chondrocyte proliferation and matrix synthesis cultured under normoxia (21% O2 ) and hypoxia (5% O2 ). We report an upregulation of chondrocyte proliferation and sulfated glycosaminoglycan (S-GAG) in hypoxic culture. Results demonstrate a synergistic effect of oxygen concentration and 1% ZnONP in up-regulation of anabolic gene expression (Type II collagen and aggrecan), and a down regulation of catabolic (MMP-13) gene expression. Furthermore, production of transcription factor hypoxia-inducible factor 1A (HIF-1A) in response to hypoxic condition to regulate chondrocyte survival under hypoxia is not affected by the presence of 1% ZnONP. Presence of 1% ZnONP appears to act to preserve homeostasis of cartilage in its hypoxic environment. © 2015 Wiley Periodicals, Inc.

Neuroprotective effect of peroxiredoxin 6 against hypoxia-induced retinal ganglion cell damage

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Kumar Anil

2010-10-01

Full Text Available Abstract Background The ability to respond to changes in the extra-intracellular environment is prerequisite for cell survival. Cellular responses to the environment include elevating defense systems, such as the antioxidant defense system. Hypoxia-evoked reactive oxygen species (ROS-driven oxidative stress is an underlying mechanism of retinal ganglion cell (RGC death that leads to blinding disorders. The protein peroxiredoxin 6 (PRDX6 plays a pleiotropic role in negatively regulating death signaling in response to stressors, and thereby stabilizes cellular homeostasis. Results We have shown that RGCs exposed to hypoxia (1% or hypoxia mimetic cobalt chloride display reduced expression of PRDX6 with higher ROS expression and activation of NF-κB. These cells undergo apoptosis, while cells with over-expression of PRDX6 demonstrate resistance against hypoxia-driven RGC death. The RGCs exposed to hypoxia either with 1% oxygen or cobalt chloride (0-400 μM, revealed ~30%-70% apoptotic cell death after 48 and 72 h of exposure. Western analysis and real-time PCR showed elevated expression of PRDX6 during hypoxia at 24 h, while PRDX6 protein and mRNA expression declined from 48 h onwards following hypoxia exposure. Concomitant with this, RGCs showed increased ROS expression and activation of NF-κB with IkB phosphorylation/degradation, as examined with H2DCF-DA and transactivation assays. These hypoxia-induced adverse reactions could be reversed by over-expression of PRDX6. Conclusion Because an abundance of PRDX6 in cells was able to attenuate hypoxia-induced RGC death, the protein could possibly be developed as a novel therapeutic agent acting to postpone RGC injury and delay the progression of glaucoma and other disorders caused by the increased-ROS-generated death signaling related to hypoxia.

Cycling hypoxia: A key feature of the tumor microenvironment.

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Michiels, Carine; Tellier, Céline; Feron, Olivier

2016-08-01

A compelling body of evidence indicates that most human solid tumors contain hypoxic areas. Hypoxia is the consequence not only of the chaotic proliferation of cancer cells that places them at distance from the nearest capillary but also of the abnormal structure of the new vasculature network resulting in transient blood flow. Hence two types of hypoxia are observed in tumors: chronic and cycling (intermittent) hypoxia. Most of the current work aims at understanding the role of chronic hypoxia in tumor growth, response to treatment and metastasis. Only recently, cycling hypoxia, with spatial and temporal fluctuations in oxygen levels, has emerged as another key feature of the tumor environment that triggers different responses in comparison to chronic hypoxia. Either type of hypoxia is associated with distinct effects not only in cancer cells but also in stromal cells. In particular, cycling hypoxia has been demonstrated to favor, to a higher extent than chronic hypoxia, angiogenesis, resistance to anti-cancer treatments, intratumoral inflammation and tumor metastasis. These review details these effects as well as the signaling pathway it triggers to switch on specific transcriptomic programs. Understanding the signaling pathways through which cycling hypoxia induces these processes that support the development of an aggressive cancer could convey to the emergence of promising new cancer treatments. Copyright © 2016 Elsevier B.V. All rights reserved.

The effect of altitude hypoxia on glucose homeostasis in men

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Larsen, J J; Hansen, J M; Olsen, Niels Vidiendal

1997-01-01

1. Exposure to altitude hypoxia elicits changes in glucose homeostasis with increases in glucose and insulin concentrations within the first few days at altitude. Both increased and unchanged hepatic glucose production (HGP) have previously been reported in response to acute altitude hypoxia...... (noradrenaline and adrenaline) and day 7 (adrenaline), but not at sea level. 4. In conclusion, insulin action decreases markedly in response to two days of altitude hypoxia, but improves with more prolonged exposure. HGP is always unchanged. The changes in insulin action may in part be explained by the changes...

Protein S-glutathionylation induced by hypoxia increases hypoxia-inducible factor-1α in human colon cancer cells.

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Jeon, Daun; Park, Heon Joo; Kim, Hong Seok

2018-01-01

Hypoxia is a common characteristic of many types of solid tumors. Intratumoral hypoxia selects for tumor cells that survive in a low oxygen environment, undergo epithelial-mesenchymal transition, are more motile and invasive, and show gene expression changes driven by hypoxia-inducible factor-1α (HIF-1α) activation. Therefore, targeting HIF-1α is an attractive strategy for disrupting multiple pathways crucial for tumor growth. In the present study, we demonstrated that hypoxia increases the S-glutathionylation of HIF-1α and its protein levels in colon cancer cells. This effect is significantly prevented by decreasing oxidized glutathione as well as glutathione depletion, indicating that S-glutathionylation and the formation of protein-glutathione mixed disulfides is related to HIF-1α protein levels. Moreover, colon cancer cells expressing glutaredoxin 1 are resistant to inducing HIF-1α and expressing hypoxia-responsive genes under hypoxic conditions. Therefore, S-glutathionylation of HIF-1α induced by tumor hypoxia may be a novel therapeutic target for the development of new drugs. Copyright © 2017 Elsevier Inc. All rights reserved.

The effects of levofloxacin on rabbit fibroblast-like synoviocytes in vitro

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Tan, Yang; Lu, Kaihang; Deng, Yu; Cao, Hong; Chen, Biao [Department of Orthopedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071 (China); Wang, Hui [Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan 430071 (China); Magdalou, Jacques [UMR 7561 CNRS-Nancy Université, Faculté de Médicine, Vandoeuvre-lès-Nancy (France); Chen, Liaobin, E-mail: lbchen@whu.edu.cn [Department of Orthopedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071 (China)

2012-12-01

It is widely accepted that tendon and cartilage are adversely affected with the toxic effects of quinolones. However, the effects of quinolones on synovium have not been deciphered completely. In this study, our main objective was to investigate the effects of levofloxacin, a typical quinolone antibiotic drug, on fibroblast-like synoviocytes (FLSs) in vitro. FLSs of rabbits were treated with levofloxacin at different concentrations (0, 14, 28, 56, 112 and 224 μM). The possible cytotoxic effects of levofloxacin on FLS were determined. Levofloxacin significantly reduced the cell viabilities, gene expression of hyaluronan synthase-2 (HAS-2), and the level of hyaluronan in FLSs. Moreover, levofloxacin-induced concentration-dependent increases of apoptosis and active caspase-3 were determined in this study. Ultrastructural damages of FLSs were observed by electron microscopy. The mRNA expression levels of matrix metalloproteinase (MMP)-3 and MMP-13 were increased in FLSs treated with levofloxacin. In addition, levofloxacin played a role in suppressing the expression of interleukin (IL)-1 and IL-6. Our data suggest that the cytotoxic effects of levofloxacin on FLS were shown to be able to affect cell viability and HA synthesis capacity. The potential mechanisms of the cytotoxic effects may be attributed to the apoptosis and increased expression of MMPs. -- Highlights: ► Levofloxacin decreases hyaluronic acid synthesis in fibroblast-like synoviocytes. ► Levofloxacin exerts pro-apoptosis effects on fibroblast-like synoviocytes. ► Levofloxacin increases gene expression of MMPs in fibroblast-like synoviocytes. ► Levofloxacin exerts anti-inflammatory effects on fibroblast-like synoviocytes.

The effects of levofloxacin on rabbit fibroblast-like synoviocytes in vitro

International Nuclear Information System (INIS)

Tan, Yang; Lu, Kaihang; Deng, Yu; Cao, Hong; Chen, Biao; Wang, Hui; Magdalou, Jacques; Chen, Liaobin

2012-01-01

It is widely accepted that tendon and cartilage are adversely affected with the toxic effects of quinolones. However, the effects of quinolones on synovium have not been deciphered completely. In this study, our main objective was to investigate the effects of levofloxacin, a typical quinolone antibiotic drug, on fibroblast-like synoviocytes (FLSs) in vitro. FLSs of rabbits were treated with levofloxacin at different concentrations (0, 14, 28, 56, 112 and 224 μM). The possible cytotoxic effects of levofloxacin on FLS were determined. Levofloxacin significantly reduced the cell viabilities, gene expression of hyaluronan synthase-2 (HAS-2), and the level of hyaluronan in FLSs. Moreover, levofloxacin-induced concentration-dependent increases of apoptosis and active caspase-3 were determined in this study. Ultrastructural damages of FLSs were observed by electron microscopy. The mRNA expression levels of matrix metalloproteinase (MMP)-3 and MMP-13 were increased in FLSs treated with levofloxacin. In addition, levofloxacin played a role in suppressing the expression of interleukin (IL)-1 and IL-6. Our data suggest that the cytotoxic effects of levofloxacin on FLS were shown to be able to affect cell viability and HA synthesis capacity. The potential mechanisms of the cytotoxic effects may be attributed to the apoptosis and increased expression of MMPs. -- Highlights: ► Levofloxacin decreases hyaluronic acid synthesis in fibroblast-like synoviocytes. ► Levofloxacin exerts pro-apoptosis effects on fibroblast-like synoviocytes. ► Levofloxacin increases gene expression of MMPs in fibroblast-like synoviocytes. ► Levofloxacin exerts anti-inflammatory effects on fibroblast-like synoviocytes.

The effect of intermittent hypobaric-hypoxia treatments on renal glutathione peroxidase activity of rats

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Paramita, I. A.; Jusman, S. W. A.

2017-08-01

Many people living at high altitudes experiencing a condition called intermittent hypobaric hypoxia (IHH). Some people even create IHH condition as an exercise for pilots, athletes, and mountaineers. In this experiment, we aimed to determine whether the protective effect of IHH is mediated through glutathione peroxidase (GPX) enzyme. The experiment’s sample is two-month-old healthy Sprague-Dawley rat kidneys weighing 200-250 g. Intermittent hypobaric hypoxia treatment is done using a Hypobaric Chamber type I that can mimic air pressure at certain altitudes: 35,000 (one minute), 30,000 (three minutes), 25,000 (five minutes), and 18,000 (30 minutes) feet. The rats were divided into five treatment groups, including a control group, hypobaric-hypoxia group, and intermittent hypobaric-hypoxia 1x, 2x, and 3x groups with each group consisting of three rats. The specific activity of GPX was measured using RANDOX and RANSEL methods. The statistical analysis of one way-ANOVA did not show significant differences between the groups (p > 0.05), although specific activities of the renal GPX of rats exposed to hypobaric-hypoxia were higher than the control group. This may be caused by the other antioxidants’ activities. In conclusion, the IHH treatment did not affect GPX activity in the rat kidneys.

Exercise Improves Mood State in Normobaric Hypoxia.

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Seo, Yongsuk; Fennell, Curtis; Burns, Keith; Pollock, Brandon S; Gunstad, John; McDaniel, John; Glickman, Ellen

2015-11-01

The purpose of this study was to quantify the efficacy of using exercise to alleviate the impairments in mood state associated with hypoxic exposure. Nineteen young, healthy men completed Automated Neuropsychological Assessment Metrics-4(th) Edition (ANAM4) versions of the mood state test before hypoxia exposure, after 60 min of hypoxia exposure (12.5% O(2)), and during and after two intensities of cycling exercise (40% and 60% adjusted Vo(2max)) under the same hypoxic conditions. Peripheral oxygen saturation (Spo(2)) and regional cerebral oxygen saturation (rSo(2)) were continuously monitored. At rest in hypoxia, Total Mood Disturbance (TMD) was significantly increased compared to baseline in both the 40% and 60% groups. TMD was significantly decreased during exercise compared to rest in hypoxia. TMD was also significantly decreased during recovery compared to rest in hypoxia. Spo(2) significantly decreased at 60 min rest in hypoxia, during exercise, and recovery compared to baseline. Regional cerebral oxygen saturation was also reduced at 60 min rest in hypoxia, during exercise, and recovery compared to baseline. The current study demonstrated that exercise at 40% and 60% of adjusted Vo(2max) attenuated the adverse effects of hypoxia on mood. These findings may have significant applied value, as negative mood states are known to impair performance in hypoxia. Further studies are needed to replicate the current finding and to clarify the possible mechanisms associated with the potential benefits of exercise on mood state in normobaric hypoxia.

Obstructive sleep apnea and cancer: effects of intermittent hypoxia?

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Kukwa, Wojciech; Migacz, Ewa; Druc, Karolina; Grzesiuk, Elzbieta; Czarnecka, Anna M

2015-01-01

Obstructive sleep apnea (OSA) is a common disorder characterized by pauses in regular breathing. Apneic episodes lead to recurrent hypoxemia-reoxygenation cycles with concomitant cellular intermittent hypoxia. Studies suggest that intermittent hypoxia in OSA may influence tumorigenesis. This review presents recent articles on the potential role of OSA in cancer development. Relevant research has focused on: molecular pathways mediating the influence of intermittent hypoxia on tumor physiology, animal and epidemiological human studies linking OSA and cancer. Current data relating OSA to risk of neoplastic disease remain scarce, but recent studies reveal the potential for a strong relation. More work is, therefore, needed on the impact of OSA on many cancer-related aspects. Results may offer enlightenment for improved cancer diagnosis and treatment.

Hypoxia-inducible factor signalling mechanisms in the central nervous system.

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Corcoran, A; O'Connor, J J

2013-08-01

In the CNS, neurones are highly sensitive to the availability of oxygen. In conditions where oxygen availability is decreased, neuronal function can be altered, leading to injury and cell death. Hypoxia has been implicated in a number of central nervous system pathologies including stroke, head trauma and neurodegenerative diseases. Cellular responses to oxygen deprivation are complex and result in activation of short- and long-term mechanisms to conserve energy and protect cells. Failure of synaptic transmission can be observed within minutes following this hypoxia. The acute effects of hypoxia on synaptic transmission are primarily mediated by altering ion fluxes across membranes, pre-synaptic effects of adenosine and other actions at glutamatergic receptors. A more long-term feature of the response of neurones to hypoxia is the activation of transcription factors such as hypoxia-inducible factor. The activation of hypoxia-inducible factor is governed by a family of dioxygenases called hypoxia-inducible factor prolyl 4 hydroxylases (PHDs). Under hypoxic conditions, PHD activity is inhibited, thereby allowing hypoxia-inducible factor to accumulate and translocate to the nucleus, where it binds to the hypoxia-responsive element sequences of target gene promoters. Inhibition of PHD activity stabilizes hypoxia-inducible factor and other proteins thus acting as a neuroprotective agent. This review will focus on the response of neuronal cells to hypoxia-inducible factor and its targets, including the prolyl hydroxylases. We also present evidence for acute effects of PHD inhibition on synaptic transmission and plasticity in the hippocampus. © 2013 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Effects of copper, hypoxia and acute temperature shifts on mitochondrial oxidation in rainbow trout (Oncorhynchus mykiss) acclimated to warm temperature

International Nuclear Information System (INIS)

Sappal, Ravinder; Fast, Mark; Stevens, Don; Kibenge, Fred; Siah, Ahmed; Kamunde, Collins

2015-01-01

Highlights: • Warm acclimation reduced the electron transport system (ETS) efficiency. • Warm acclimation altered the effects of acute temperature shift, hypoxia and Cu on ETS. • Warm acclimation increased thermal sensitivity of state 3 and reduced that of state 4. • Cu stimulated while hypoxia inhibited ETS respiratory activity. • Interactions of Cu and hypoxia on the ETS and plasma metabolites were antagonistic. - Abstract: Temperature fluctuations, hypoxia and metals pollution frequently occur simultaneously or sequentially in aquatic systems and their interactions may confound interpretation of their biological impacts. With a focus on energy homeostasis, the present study examined how warm acclimation influences the responses and interactions of acute temperature shift, hypoxia and copper (Cu) exposure in fish. Rainbow trout (Oncorhynchus mykiss) were acclimated to cold (11 °C; control) and warm (20 °C) temperature for 3 weeks followed by exposure to environmentally realistic levels of Cu and hypoxia for 24 h. Subsequently, mitochondrial electron transport system (ETS) respiratory activity supported by complexes I–IV (CI–IV), plasma metabolites and condition indices were measured. Warm acclimation reduced fish condition, induced aerobic metabolism and altered the responses of fish to acute temperature shift, hypoxia and Cu. Whereas warm acclimation decelerated the ETS and increased the sensitivity of maximal oxidation rates of the proximal (CI and II) complexes to acute temperature shift, it reduced the thermal sensitivity of state 4 (proton leak). Effects of Cu with and without hypoxia were variable depending on the acclimation status and functional index. Notably, Cu stimulated respiratory activity in the proximal ETS segments, while hypoxia was mostly inhibitory and minimized the stimulatory effect of Cu. The effects of Cu and hypoxia were modified by temperature and showed reciprocal antagonistic interaction on the ETS and plasma

Effects of copper, hypoxia and acute temperature shifts on mitochondrial oxidation in rainbow trout (Oncorhynchus mykiss) acclimated to warm temperature

Energy Technology Data Exchange (ETDEWEB)

Sappal, Ravinder [Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3 (Canada); Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3 (Canada); Fast, Mark [Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3 (Canada); Stevens, Don [Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3 (Canada); Kibenge, Fred [Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3 (Canada); Siah, Ahmed [British Columbia Centre for Aquatic Health Sciences, 871A Island Highway, Campbell River, British Columbia V9W 2C2 (Canada); Kamunde, Collins, E-mail: ckamunde@upei.ca [Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3 (Canada)

2015-12-15

Highlights: • Warm acclimation reduced the electron transport system (ETS) efficiency. • Warm acclimation altered the effects of acute temperature shift, hypoxia and Cu on ETS. • Warm acclimation increased thermal sensitivity of state 3 and reduced that of state 4. • Cu stimulated while hypoxia inhibited ETS respiratory activity. • Interactions of Cu and hypoxia on the ETS and plasma metabolites were antagonistic. - Abstract: Temperature fluctuations, hypoxia and metals pollution frequently occur simultaneously or sequentially in aquatic systems and their interactions may confound interpretation of their biological impacts. With a focus on energy homeostasis, the present study examined how warm acclimation influences the responses and interactions of acute temperature shift, hypoxia and copper (Cu) exposure in fish. Rainbow trout (Oncorhynchus mykiss) were acclimated to cold (11 °C; control) and warm (20 °C) temperature for 3 weeks followed by exposure to environmentally realistic levels of Cu and hypoxia for 24 h. Subsequently, mitochondrial electron transport system (ETS) respiratory activity supported by complexes I–IV (CI–IV), plasma metabolites and condition indices were measured. Warm acclimation reduced fish condition, induced aerobic metabolism and altered the responses of fish to acute temperature shift, hypoxia and Cu. Whereas warm acclimation decelerated the ETS and increased the sensitivity of maximal oxidation rates of the proximal (CI and II) complexes to acute temperature shift, it reduced the thermal sensitivity of state 4 (proton leak). Effects of Cu with and without hypoxia were variable depending on the acclimation status and functional index. Notably, Cu stimulated respiratory activity in the proximal ETS segments, while hypoxia was mostly inhibitory and minimized the stimulatory effect of Cu. The effects of Cu and hypoxia were modified by temperature and showed reciprocal antagonistic interaction on the ETS and plasma

Hypoxia-inducible factor 1–mediated characteristic features of cancer cells for tumor radioresistance

International Nuclear Information System (INIS)

Harada, Hiroshi

2016-01-01

Tumor hypoxia has been attracting increasing attention in the fields of radiation biology and oncology since Thomlinson and Gray detected hypoxic cells in malignant solid tumors and showed that they exert a negative impact on the outcome of radiation therapy. This unfavorable influence has, at least partly, been attributed to cancer cells acquiring a radioresistant phenotype through the activation of the transcription factor, hypoxia-inducible factor 1 (HIF-1). On the other hand, accumulating evidence has recently revealed that, even though HIF-1 is recognized as an important regulator of cellular adaptive responses to hypoxia, it may not become active and induce tumor radioresistance under hypoxic conditions only. The mechanisms by which HIF-1 is activated in cancer cells not only under hypoxic conditions, but also under normoxic conditions, through cancer-specific genetic alterations and the resultant imbalance in intermediate metabolites have been summarized herein. The relevance of the HIF-1–mediated characteristic features of cancer cells, such as the production of antioxidants through reprogramming of the glucose metabolic pathway and cell cycle regulation, for tumor radioresistance has also been reviewed

Protective effect of hypoxia in the ram testis during single and split-dose X-irradiation

International Nuclear Information System (INIS)

Vliet, J. van; Wensing, C.J.G.; Bootsma, A.L.; Peperzeel, H.A. van; Schipper, J.

1988-01-01

Spertogonial stem-cell survival in the ram was studied after single (6Gy) and split-dose X-irradiation both under normal and hypoxic conditions. Hypoxia was induced by inflation of an occluder implanted around the testicular artery. The occluders were inflated about 10 min before irradiation and deflated immediately after. Stem-cell survival was measured at 5 or 7 weeks after irradiation by determination of the Repopulation Index (RI) in histological testis sections. The RI-values after fractionated irradiation were only half those after single dose irradiation. Hypoxia had a protective effect on the stem-cell survival. After split-dose irradiation under hypoxic conditions two times more stem cells survived than under normal oxic conditions; the RI-values increased from 34% (oxic) to 68% (hypoxic). This effect of hypoxia was also found after single dose irradiation where the RI-values increased from 68% (oxic) to 84% (hypoxic). The development of the epithelium in repopulated tubules was also studied. Under hypoxia, a significantly higher fraction of tubules with complete epithelium was found after single (38 vs. 4%) as well as after split-dose irradiation (12 vs. 0%)

[Effects of interleukin-18 and hypoxia-inducible factor-1α in serum and gingival tissues of rat model with periodontitis exposed to chronic intermittent hypoxia].

Science.gov (United States)

Wang, Bin; Wang, Xiaoqin

2015-08-01

This study evaluates the expression of interleukin-18 (IL-18) and hypoxia-inducible factor (HIF)-lα in rat periodontitis model exposed to normoxia and chronic intermittent hypoxia (CIH) environments. The possible correlation between periodontitis and obstructive sleep apnea-hypopnea syndrome (OSAHS) was also investigated. Methods: Thirty-two Sprague-Dawley (SD) rats were randomly assigned into four groups: normoxia control, normoxia periodontitis, hypoxia control, and hypoxia periodontitis groups. The periodontitis models were established by ligating the bilateral maxillary second molars and employing high-carbohydrate diets. Rats in hypoxia control and hypoxia periodontitis groups were exposed to CIH treatment mimicking a moderately severe OSAHS condition. All animals were sacrificed after eight weeks, and the clinical periodontal indexes were detected. The levels of IL-18 and HIF-1α in serum and gingival tissues were determined using enzyme-linked immunosorbent assay (ELISA). The correlation between attachment loss (AL) and the levels of IL-18 and HIF-lα in hypoxia periodontitis group was evaluated. The levels of IL-18 and HIF-lα in hypoxia periodontitis group were significantly higher than that in normoxia periodontitis and hypoxia control groups (Pperiodontal tissues, which is correlated with IL-18 and HIF-lα levels.

Hypoxia in the changing marine environment

Science.gov (United States)

Zhang, J.; Cowie, G.; Naqvi, S. W. A.

2013-03-01

The predicted future of the global marine environment, as a combined result of forcing due to climate change (e.g. warming and acidification) and other anthropogenic perturbation (e.g. eutrophication), presents a challenge to the sustainability of ecosystems from tropics to high latitudes. Among the various associated phenomena of ecosystem deterioration, hypoxia can cause serious problems in coastal areas as well as oxygen minimum zones in the open ocean (Diaz and Rosenberg 2008 Science 321 926-9, Stramma et al 2008 Science 320 655-8). The negative impacts of hypoxia include changes in populations of marine organisms, such as large-scale mortality and behavioral responses, as well as variations of species distributions, biodiversity, physiological stress, and other sub-lethal effects (e.g. growth and reproduction). Social and economic activities that are related to services provided by the marine ecosystems, such as tourism and fisheries, can be negatively affected by the aesthetic outcomes as well as perceived or real impacts on seafood quality (STAP 2011 (Washington, DC: Global Environment Facility) p 88). Moreover, low oxygen concentration in marine waters can have considerable feedbacks to other compartments of the Earth system, like the emission of greenhouse gases to the atmosphere, and can affect the global biogeochemical cycles of nutrients and trace elements. It is of critical importance to prediction and adaptation strategies that the key processes of hypoxia in marine environments be precisely determined and understood (cf Zhang et al 2010 Biogeosciences 7 1-24).

Hypoxia Room

Data.gov (United States)

Federal Laboratory Consortium — The Hypoxia Room is a 8x8x8 ft. clear vinyl plastic and aluminum frame construction enclosure located within USAREIM laboratory 028. The Hypoxia Room (manufactured...

Protective effects of two constituents of Chinese herbs on spinal motor neurons from embryonic rats with hypoxia injury.

Science.gov (United States)

Chen, Jian-Feng; Fan, Jian; Tian, Xiao-Wu; Tang, Tian-Si

2012-01-01

Neuroprotective agents are becoming significant tools in the repair of central nervous system injuries. In this study, we determined whether ginkgolides (Gin, extract of GinkgoBiloba) and Acanthopanax senticosus saponins (ASS, flavonoids extracted from Acanthopanax herbal preparations) have protective effects on rat spinal cords exposed to anoxia and we explored the mechanisms that underlie the protective effects. Spinal motor neurons (SMNs) from rat spinal cords were obtained and divided into five groups with 10 wells in each group. In control group, SMNs suffered no injury under normal oxygen; in hypoxia- inducible (HI) group, SMNs suffered injury from hypoxia; in Gin group, 37.5µg/ml Gin were used before 24 hrs of hypoxia; in ASS group, 50µg/ml ASS were used before 24 hrs of hypoxia;in glial cell-lined derived neurotrophic factor (GDNF) group, 0.1µg/ml GDNF were used before 24 hrs of hypoxia. Changes in morphology, neuron viability, and lactate dehydrogenase (LDH) release were observed. In addition, the expression of HIF-1α induced by hypoxia was measured. The neuronal viability in the Gin, ASS, and GDNF pretreated groups was higher than that in the HI group (P0.05). The quantity of LDH released in the three pretreated groups was lower than that in the HI group (Phypoxic neurons.

Efficacy and biological effects of techniques used to induce hypoxia in tumors

International Nuclear Information System (INIS)

Rockwell, S.; Moulder, J.E.; Martin, D.F.

1985-01-01

The authors tested several aspects of the assumptions using BA1112 rat rhabdomyosacromas and EMT6 mouse mammary tumors. Both techniques were effective in producing hypoxia: survival curves for tumors made hypoxic by the 2 techniques were the same, and were indistinguishable from survival curves for hypoxic tumor cells in vitro. Induction of hypoxia for the 30-60 min necessary for irradiation did not alter the yield or clonogenicity of cells suspended from the tumors. Longer clamping was cytotoxic. Clamping did not alter tumor growth unless a major blood vessel was injured. However, clamping BA1112 tumors for 30 min and removing the clamp just before irradiation altered the tumor cell survival curve and TCD/sub 50/. Anesthesia or restrain, often used during clamping, can have major effects

Gill and lung ventilation responses to steady-state aquatic hypoxia and hyperoxia in the bullfrog tadpole.

Science.gov (United States)

West, N H; Burggren, W W

1982-02-01

Gill ventilation frequency (fG), the pressure amplitude (PBC) and stroke volume (VS) of buccal ventilation cycles, the frequency of air breaths (fL), water flow over the gills (VW), gill oxygen uptake (MGO2), oxygen utilization (U), and heart frequency (fH) have been measured in unanaesthetized, air breathing Rana catesbeiana tadpoles (stage XVI-XIX). The animals were unrestrained except for ECG leads or cannulae, and were able to surface voluntarily for air breathing. They were subjected to aquatic normoxia, hyperoxia and three levels of aquatic hypoxia, and their respiratory responses recorded in the steady state. The experiments were performed at 20 +/- 0.5 degrees C. In hyperoxia there was an absence of air breathing, and fG, PBC and VW fell from the normoxic values, while U increased, resulting in no significant change in MGO2. Animals in normoxia showed a very low fL which increased in progressively more hypoxic states. VW increased from the normoxic value in mild hypoxia (PO2 = 96 +/- 2 mm Hg), but fell, associated with a reduction in PBC, in moderate (PO2 = 41 +/- 1 mm Hg) and severe (PO2 = 21 +/- 3 mm Hg) hypoxia in the presence of lung ventilation. Gill MGO2 was not significantly different from the normoxic value in mild hypoxia but fell in moderate hypoxia, while in severe hypoxia oxygen was lost to the ventilating water from the blood perfusing the gills. There was no significant change in fH from the normoxic value in either hypoxia or hyperoxia. These data indicate, that in the bimodally breathing bullfrog tadpole, aquatic PO2 exerts a strong control over both gill and lung ventilation. Furthermore, there is an interaction between gill and lung ventilation such that the onset of a high frequency of lung ventilation in moderate and severe hypoxia promotes a suppression of gill ventilation cycles.

Biliverdin reductase/bilirubin mediates the anti-apoptotic effect of hypoxia in pulmonary arterial smooth muscle cells through ERK1/2 pathway

International Nuclear Information System (INIS)

Song, Shasha; Wang, Shuang; Ma, Jun; Yao, Lan; Xing, Hao; Zhang, Lei; Liao, Lin; Zhu, Daling

2013-01-01

Inhibition of pulmonary arterial smooth muscle cell (PASMC) apoptosis induced by hypoxia plays an important role in pulmonary arterial remodeling leading to aggravate hypoxic pulmonary arterial hypertension. However, the mechanisms of hypoxia acting on PASMC apoptosis remain exclusive. Biliverdin reductase (BVR) has many essential biologic roles in physiological and pathological processes. Nevertheless, it is unclear whether the hypoxia-induced inhibition on PASMC apoptosis is mediated by BVR. In the present work, we found BVR majorly localized in PASMCs and was up-regulated in levels of protein and mRNA by hypoxia. Then we studied the contribution of BVR to anti-apoptotic response of hypoxia in PASMCs. Our results showed that siBVR, blocking generation of bilirubin, reversed the effect of hypoxia on enhancing cell survival and apoptotic protein (Bcl-2, procasepase-9, procasepase-3) expression, preventing nuclear shrinkage, DNA fragmentation and mitochondrial depolarization in starved PASMCs, which were recovered by exogenous bilirubin. Moreover, the inhibitory effect of bilirubin on PASMC apoptosis under hypoxic condition was blocked by the inhibitor of ERK1/2 pathway. Taken together, our data indicate that BVR contributes to the inhibitory process of hypoxia on PASMC apoptosis, which is mediated by bilirubin through ERK1/2 pathway. Highlights: • BVR expresses in PASMC and is up-regulated by hypoxia in protein and mRNA levels. • BVR/bilirubin contribute to the inhibitive process of hypoxia on PASMC apoptosis. • Bilirubin protects PASMC from apoptosis under hypoxia via ERK1/2 pathway

Biliverdin reductase/bilirubin mediates the anti-apoptotic effect of hypoxia in pulmonary arterial smooth muscle cells through ERK1/2 pathway

Energy Technology Data Exchange (ETDEWEB)

Song, Shasha [Department of Biopharmaceutical Sciences, College of Pharmacy, Harbin Medical, University (Daqing), Daqing 163319 (China); Wang, Shuang [Department of Biopharmaceutical Sciences, College of Pharmacy, Harbin Medical, University (Daqing), Daqing 163319 (China); Biopharmaceutical Key Laboratory of Heilongjiang Province, Harbin 150081 (China); Ma, Jun; Yao, Lan; Xing, Hao; Zhang, Lei; Liao, Lin [Department of Biopharmaceutical Sciences, College of Pharmacy, Harbin Medical, University (Daqing), Daqing 163319 (China); Zhu, Daling, E-mail: dalingz@yahoo.com [Department of Biopharmaceutical Sciences, College of Pharmacy, Harbin Medical, University (Daqing), Daqing 163319 (China); Biopharmaceutical Key Laboratory of Heilongjiang Province, Harbin 150081 (China)

2013-08-01

Inhibition of pulmonary arterial smooth muscle cell (PASMC) apoptosis induced by hypoxia plays an important role in pulmonary arterial remodeling leading to aggravate hypoxic pulmonary arterial hypertension. However, the mechanisms of hypoxia acting on PASMC apoptosis remain exclusive. Biliverdin reductase (BVR) has many essential biologic roles in physiological and pathological processes. Nevertheless, it is unclear whether the hypoxia-induced inhibition on PASMC apoptosis is mediated by BVR. In the present work, we found BVR majorly localized in PASMCs and was up-regulated in levels of protein and mRNA by hypoxia. Then we studied the contribution of BVR to anti-apoptotic response of hypoxia in PASMCs. Our results showed that siBVR, blocking generation of bilirubin, reversed the effect of hypoxia on enhancing cell survival and apoptotic protein (Bcl-2, procasepase-9, procasepase-3) expression, preventing nuclear shrinkage, DNA fragmentation and mitochondrial depolarization in starved PASMCs, which were recovered by exogenous bilirubin. Moreover, the inhibitory effect of bilirubin on PASMC apoptosis under hypoxic condition was blocked by the inhibitor of ERK1/2 pathway. Taken together, our data indicate that BVR contributes to the inhibitory process of hypoxia on PASMC apoptosis, which is mediated by bilirubin through ERK1/2 pathway. Highlights: • BVR expresses in PASMC and is up-regulated by hypoxia in protein and mRNA levels. • BVR/bilirubin contribute to the inhibitive process of hypoxia on PASMC apoptosis. • Bilirubin protects PASMC from apoptosis under hypoxia via ERK1/2 pathway.

Perinatal Hypoxia and Ischemia in Animal Models of Schizophrenia

Directory of Open Access Journals (Sweden)

Dimitri Hefter

2018-03-01

Full Text Available Intrauterine or perinatal complications constitute a major risk for psychiatric diseases. Infants who suffered from hypoxia–ischemia (HI are at twofold risk to develop schizophrenia in later life. Several animal models attempt to reproduce these complications to study the yet unknown steps between an insult in early life and outbreak of the disease decades later. However, it is very challenging to find the right type and severity of insult leading to a disease-like phenotype in the animal, but not causing necrosis and focal neurological deficits. By contrast, too mild, repetitive insults may even be protective via conditioning effects. Thus, it is not surprising that animal models of hypoxia lead to mixed results. To achieve clinically translatable findings, better protocols are urgently needed. Therefore, we compare widely used models of hypoxia and HI and propose future directions for the field.

Effect of hypoxia on specific dynamic action and postprandial cardiovascular physiology in rainbow trout (Oncorhynchus mykiss).

Science.gov (United States)

Eliason, Erika J; Farrell, Anthony P

2014-05-01

Fish routinely encounter hypoxic environments, which may have detrimental effects on digestion and performance. The present study measured oxygen consumption (MO2), gastrointestinal blood flow (GBF), cardiac output (Vb) and heart rate (f(H)) in rainbow trout Oncorhynchus mykiss at 10°C-11.5°C while exposed to a 1.5-h step-wise hypoxia treatment (80%, 60% and 40% saturation=16.7, 12.6 and 8.4 kPa, respectively), which began 4 h after being fed 1% of their body mass. GBF and f(H) significantly decreased by 41 and 25%-29%, respectively, at the most severe hypoxia step (40% saturation), while MO2 and Vb were maintained throughout the entire hypoxia exposure. Thus, GBF and f(H) were more sensitive to hypoxia than MO2 or Vb in digesting rainbow trout. Subsequent to the hypoxic exposure, the fish were returned to normoxia and monitored for a total of 50h after feeding. While the magnitude of SDA was unaffected, peak postprandial MO2 was reduced by 17%, and the duration of specific dynamic action (SDA) was prolonged by 6h in hypoxia-treated fish when compared to control fish. In conclusion, digestive performance was compromised both during and after the hypoxic exposure, which could lead to negative effects on growth. Copyright © 2014 Elsevier Inc. All rights reserved.

Long-term potentiation protects rat hippocampal slices from the effects of acute hypoxia.

Science.gov (United States)

Youssef, F F; Addae, J I; McRae, A; Stone, T W

2001-07-13

We have previously shown that long-term potentiation (LTP) decreases the sensitivity of glutamate receptors in the rat hippocampal CA1 region to exogenously applied glutamate agonists. Since the pathophysiology of hypoxia/ischemia involves increased concentration of endogenous glutamate, we tested the hypothesis that LTP could reduce the effects of hypoxia in the hippocampal slice. The effects of LTP on hypoxia were measured by the changes in population spike potentials (PS) or field excitatory post-synaptic potentials (fepsps). Hypoxia was induced by perfusing the slice with (i) artificial CSF which had been pre-gassed with 95%N2/5% CO2; (ii) artificial CSF which had not been pre-gassed with 95% O2/5% CO2; or (iii) an oxygen-glucose deprived (OGD) medium which was similar to (ii) and in which the glucose had been replaced with sucrose. Exposure of a slice to a hypoxic medium for 1.5-3.0 min led to a decrease in the PS or fepsps; the potentials recovered to control levels within 3-5 min. Repeat exposure, 45 min later, of the same slice to the same hypoxic medium for the same duration as the first exposure caused a reduction in the potentials again; there were no significant differences between the degree of reduction caused by the first or second exposure for all three types of hypoxic media (P>0.05; paired t-test). In some of the slices, two episodes of LTP were induced 25 and 35 min after the first hypoxic exposure; this caused inhibition of reduction in potentials caused by the second hypoxic insult which was given at 45 min after the first; the differences in reduction in potentials were highly significant for all the hypoxic media used (Peffects of LTP were not prevented by cyclothiazide or inhibitors of NO synthetase compounds that have been shown to be effective in blocking the effects of LTP on the actions of exogenously applied AMPA and NMDA, respectively. The neuroprotective effects of LTP were similar to those of propentofylline, a known neuroprotective

[Effects of hypoxia on the phenotype transformation of human dermal fibroblasts to myofibroblasts and the mechanism].

Science.gov (United States)

Zhao, B; Han, F; Zhang, W; Wang, X J; Zhang, J; Yang, F F; Shi, J H; Su, L L; Hu, D H

2017-06-20

Objective: To investigate the effects of hypoxia on the phenotype transformation of human dermal fibroblasts to myofibroblasts and the mechanism. Methods: The third passage of healthy adult human dermal fibroblasts in logarithmic phase were cultured in DMEM medium containing 10% fetal bovine serum for the following five experiments. (1) In experiments 1, 2, and 3, cells were divided into normoxia group and hypoxia group according to the random number table, with 10 dishes in each group. Cells of normoxia group were cultured in incubator containing 21% oxygen, while those of hypoxia group with 1% oxygen. At post culture hour (PCH) 0 and 48, 5 dishes of cells were collected from each group, respectively. mRNA expressions of markers of myofibroblasts including alpha smooth muscle actin (α-SMA), type Ⅰ collagen, and type Ⅲ collagen of cells were determined with real time fluorescent quantitative reverse transcription polymerase chain reaction in experiment 1. Protein expressions of α-SMA, type Ⅰ collagen, and type Ⅲ collagen of cells were determined with Western blotting in experiment 2. The protein expression of nuclear factor-kappa B (NF-κB) of cells was determined with Western blotting in experiment 3. (2) In experiment 4, cells were divided into normoxia group, hypoxia group, and hypoxia+ pyrrolidine dithiocarbamate (PDTC) group according to the random number table, with 5 dishes in each group. Cells in the former two groups were treated the same as those in experiment 1. Cells in hypoxia+ PDTC group were treated the same as those in hypoxia group plus adding 4 mL PDTC with a final molarity of 10 μmol/L in the culture medium. At PCH 48, the protein expression of NF-κB of cells was determined with Western blotting. (3) In experiment 5, cells were divided into normoxia group, hypoxia group, hypoxia+ PDTC group, and normoxia+ PDTC group according to the random number table, with 5 dishes in each group. Cells in the former three groups were treated the

Radioprotective effect of dextran sulphate and aerogenic hypoxia on intestinal crypt stem cells in mice

International Nuclear Information System (INIS)

Vacek, A.; Bartonickova, A.; Rotkovska, D.; Konoplyanikova, O.A.; Konoplyanikov, A.G.

1991-01-01

A single intraperitoneal injection of dextran sulfate given 6 h before irradiation produced higher numbers of microcolonies of intestinal crypt stem cells in whole-body irradiated mice than an injection of saline in control mice. If dextran sulfate and hypoxia are combined, the radioprotective effect of hypoxia on intestinal crypt stem cells depends on the time interval between irradiation and administration of dextran sulfate. (author). 2 figs., 12 refs

Human erythropoietin response to hypocapnic hypoxia, normocapnic hypoxia, and hypocapnic normoxia

DEFF Research Database (Denmark)

Klausen, T; Christensen, H; Hansen, J M

1996-01-01

exposed to 2 h each of hypocapnic hypoxia, normocapnic hypoxia, hypocapnic normoxia, and normal breathing of room air (control experiment). During the control experiment, serum-EPO showed significant variations (ANOVA P = 0.047) with a 15% increase in mean values. The serum-EPO measured in the other...... (10% Co2 with 10% O2) to the hypoxic gas mixture. This elicited an increased ventilation, unaltered arterial pH and haemoglobin oxygen affinity, a lower degree of hypoxia than during hypocapnic hypoxia, and no significant changes in serum-EPO (ANOVA P > 0.05). Hypocapnic normoxia, produced...

Hypoxia promotes apoptosis of neuronal cells through hypoxia-inducible factor-1α-microRNA-204-B-cell lymphoma-2 pathway.

Science.gov (United States)

Wang, Xiuwen; Li, Ji; Wu, Dongjin; Bu, Xiangpeng; Qiao, Yong

2016-01-01

Neuronal cells are highly sensitive to hypoxia and may be subjected to apoptosis when exposed to hypoxia. Several apoptosis-related genes and miRNAs involve in hypoxia-induced apoptosis. This study aimed to examine the role of HIF1α-miR-204-BCL-2 pathway in hypoxia-induced apoptosis in neuronal cells. Annexin V/propidium iodide assay was performed to analyze cell apoptosis in AGE1.HN and PC12 cells under hypoxic or normoxic conditions. The expression of BCL-2 and miR-204 were determined by Western blot and qRT-PCR. The effects of miR-204 overexpression or knockdown on the expression of BCL-2 were evaluated by luciferase assay and Western blot under hypoxic or normoxic conditions. HIF-1α inhibitor YC-1 and siHIF-1α were employed to determine the effect of HIF-1α on the up-regulation of miR-204 and down-regulation of BCL-2 induced by hypoxia. Apoptosis assay showed the presence of apoptosis induced by hypoxia in neuronal cells. Moreover, we found that hypoxia significantly down-regulated the expression of BCL-2, and increased the mRNA level of miR-204 in neuronal cells than that in control. Bioinformatic analysis and luciferase reporter assay demonstrated that miR-204 directly targeted and regulated the expression of BCL-2. Specifically, the expression of BCL-2 was inhibited by miR-204 mimic and enhanced by miR-204 inhibitor. Furthermore, we detected that hypoxia induced cell apoptosis via HIF-1α/miR-204/BCL-2 in neuronal cells. This study demonstrated that HIF-1α-miR-204-BCL-2 pathway contributed to apoptosis of neuronal cells induced by hypoxia, which could potentially be exploited to prevent spinal cord ischemia-reperfusion injury. © 2015 by the Society for Experimental Biology and Medicine.

Neuroprotective Role of Intermittent Hypobaric Hypoxia in Unpredictable Chronic Mild Stress Induced Depression in Rats

Science.gov (United States)

Deep, Satayanarayan; Prasad, Dipti; Singh, Shashi Bala; Khan, Nilofar

2016-01-01

Hypoxic exposure results in several pathophysiological conditions associated with nervous system, these include acute and chronic mountain sickness, loss of memory, and high altitude cerebral edema. Previous reports have also suggested the role of hypoxia in pathogenesis of depression and related psychological conditions. On the other hand, sub lethal intermittent hypoxic exposure induces protection against future lethal hypoxia and may have beneficial effect. Therefore, the present study was designed to explore the neuroprotective role of intermittent hypobaric hypoxia (IHH) in Unpredictable Chronic Mild Stress (UCMS) induced depression like behaviour in rats. The IHH refers to the periodic exposures to hypoxic conditions interrupted by the normoxic or lesser hypoxic conditions. The current study examines the effect of IHH against UCMS induced depression, using elevated plus maze (EPM), open field test (OFT), force swim test (FST), as behavioural paradigm and related histological and molecular approaches. The data indicated the UCMS induced depression like behaviour as evident from decreased exploration activity in OFT with increased anxiety levels in EPM, and increased immobility time in the FST; whereas on providing the IHH (5000m altitude, 4hrs/day for two weeks) these behavioural changes were ameliorated. The morphological and molecular studies also validated the neuroprotective effect of IHH against UCMS induced neuronal loss and decreased neurogenesis. Here, we also explored the role of Brain-Derived Neurotrophic Factor (BDNF) in anticipatory action of IHH against detrimental effect of UCMS as upon blocking of BDNF-TrkB signalling the beneficial effect of IHH was nullified. Taken together, the findings of our study demonstrate that the intermittent hypoxia has a therapeutic potential similar to an antidepressant in animal model of depression and could be developed as a preventive therapeutic option against this pathophysiological state. PMID:26901349

Neuroprotective Role of Intermittent Hypobaric Hypoxia in Unpredictable Chronic Mild Stress Induced Depression in Rats.

Directory of Open Access Journals (Sweden)

Neetu Kushwah

Full Text Available Hypoxic exposure results in several pathophysiological conditions associated with nervous system, these include acute and chronic mountain sickness, loss of memory, and high altitude cerebral edema. Previous reports have also suggested the role of hypoxia in pathogenesis of depression and related psychological conditions. On the other hand, sub lethal intermittent hypoxic exposure induces protection against future lethal hypoxia and may have beneficial effect. Therefore, the present study was designed to explore the neuroprotective role of intermittent hypobaric hypoxia (IHH in Unpredictable Chronic Mild Stress (UCMS induced depression like behaviour in rats. The IHH refers to the periodic exposures to hypoxic conditions interrupted by the normoxic or lesser hypoxic conditions. The current study examines the effect of IHH against UCMS induced depression, using elevated plus maze (EPM, open field test (OFT, force swim test (FST, as behavioural paradigm and related histological and molecular approaches. The data indicated the UCMS induced depression like behaviour as evident from decreased exploration activity in OFT with increased anxiety levels in EPM, and increased immobility time in the FST; whereas on providing the IHH (5000m altitude, 4hrs/day for two weeks these behavioural changes were ameliorated. The morphological and molecular studies also validated the neuroprotective effect of IHH against UCMS induced neuronal loss and decreased neurogenesis. Here, we also explored the role of Brain-Derived Neurotrophic Factor (BDNF in anticipatory action of IHH against detrimental effect of UCMS as upon blocking of BDNF-TrkB signalling the beneficial effect of IHH was nullified. Taken together, the findings of our study demonstrate that the intermittent hypoxia has a therapeutic potential similar to an antidepressant in animal model of depression and could be developed as a preventive therapeutic option against this pathophysiological state.

The effects of doxycycline and micronized purified flavonoid fraction on human vein wall remodeling are not hypoxia-inducible factor pathway-dependent.

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Lim, Chung Sim; Kiriakidis, Serafim; Paleolog, Ewa M; Davies, Alun H

2012-10-01

Doxycycline and micronized purified flavonoid fraction (MPFF) modulate vein wall remodeling that may be associated with hypoxia in varicose veins (VVs), vein graft stenosis, and deep venous thrombosis. We recently reported that in vitro exposure of non-VV (NVVs) and VVs to hypoxic conditions activates the hypoxia-inducible factor (HIF) pathway. This study investigated the in vitro effects of doxycycline and MPFF on the HIF pathway in hypoxic NVVs and VVs. Six NVVs and six VVs obtained from surgery were used to prepare vein organ cultures, which were exposed to hypoxia (1% O(2)), with and without MPFF (10(-5) mol/L) or doxycycline (5 μg/mL) for 16 hours. The veins were analyzed for HIF-1α, HIF-2α, and their target gene expression, with real-time polymerase chain reaction and Western blot. The differences between gene expressions were tested with one-way analysis of variance with repeated measures, followed by the Dunnett test for multiple comparisons. P factor, B-cell lymphoma 2/adenovirus E1B 19-kDa protein-interacting protein 3, prolyl hydroxylase domain-2, and prolyl hydroxylase domain-3, was not significantly altered in NVVs and VVs exposed to hypoxia and treated with doxycycline or MPFF compared with those untreated. Doxycycline and MPFF at a concentration corresponding to a therapeutic dose do not alter the activation of the HIF pathway in NVV and VV organ cultures exposed to hypoxia. Our findings suggest vein wall remodeling actions in NVVs and VVs are likely not HIF-dependent. Copyright © 2012 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.

Intermittent Hypoxia Causes Inflammation and Injury to Human Adult Cardiac Myocytes.

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Wu, Jing; Stefaniak, Joanna; Hafner, Christina; Schramel, Johannes Peter; Kaun, Christoph; Wojta, Johann; Ullrich, Roman; Tretter, Verena Eva; Markstaller, Klaus; Klein, Klaus Ulrich

2016-02-01

Intermittent hypoxia may occur in a number of clinical scenarios, including interruption of myocardial blood flow or breathing disorders such as obstructive sleep apnea. Although intermittent hypoxia has been linked to cardiovascular and cerebrovascular disease, the effect of intermittent hypoxia on the human heart is not fully understood. Therefore, in the present study, we compared the cellular responses of cultured human adult cardiac myocytes (HACMs) exposed to intermittent hypoxia and different conditions of continuous hypoxia and normoxia. HACMs were exposed to intermittent hypoxia (0%-21% O2), constant mild hypoxia (10% O2), constant severe hypoxia (0% O2), or constant normoxia (21% O2), using a novel cell culture bioreactor with gas-permeable membranes. Cell proliferation, lactate dehydrogenase release, vascular endothelial growth factor release, and cytokine (interleukin [IL] and macrophage migration inhibitory factor) release were assessed at baseline and after 8, 24, and 72 hours of exposure. A signal transduction pathway finder array was performed to determine the changes in gene expression. In comparison with constant normoxia and constant mild hypoxia, intermittent hypoxia induced earlier and greater inflammatory response and extent of cell injury as evidenced by lower cell numbers and higher lactate dehydrogenase, vascular endothelial growth factor, and proinflammatory cytokine (IL-1β, IL-6, IL-8, and macrophage migration inhibitory factor) release. Constant severe hypoxia showed more detrimental effects on HACMs at later time points. Pathway analysis demonstrated that intermittent hypoxia primarily altered gene expression in oxidative stress, Wnt, Notch, and hypoxia pathways. Intermittent and constant severe hypoxia, but not constant mild hypoxia or normoxia, induced inflammation and cell injury in HACMs. Cell injury occurred earliest and was greatest after intermittent hypoxia exposure. Our in vitro findings suggest that intermittent hypoxia

Synergistic effects of hypoxia and increasing CO2 on benthic invertebrates of the central Chilean coast

KAUST Repository

Steckbauer, Alexandra

2015-07-10

Ocean acidification (OA) and hypoxic events are an increasing worldwide problem, but the synergetic effects of these factors are seldom explored. However, this synergetic occurrence of stressors is prevalent. The coastline of Chile not only suffers from coastal hypoxia but the cold, oxygen-poor waters in upwelling events are also supersaturated in CO2, a study site to explore the combined effect of OA and hypoxia. We experimentally evaluated the metabolic response of different invertebrate species (2 anthozoans, 9 molluscs, 4 crustaceans, 2 echinoderms) of the coastline of central Chile (33°30′S, 71°37′W) to hypoxia and OA within predicted levels and in a full factorial design. Organisms were exposed to 4 different treatments (ambient, low oxygen, high CO2, and the combination of low oxygen and high CO2) and metabolism was measured after 3 and 6 days. We show that the combination of hypoxia and increased pCO2 reduces the respiration significantly, compared to a single stressor. The evaluation of synergistic pressures, a more realistic scenario than single stressors, is crucial to evaluate the effect of future changes for coastal species and our results provide the first insight on what might happen in the next 100 years.

Synergistic effects of hypoxia and increasing CO2 on benthic invertebrates of the central Chilean coast

KAUST Repository

Steckbauer, Alexandra; Ramajo, Laura; Hendriks, Iris E.; Fernandez, Miriam; Lagos, Nelson A.; Prado, Luis; Duarte, Carlos M.

2015-01-01

Ocean acidification (OA) and hypoxic events are an increasing worldwide problem, but the synergetic effects of these factors are seldom explored. However, this synergetic occurrence of stressors is prevalent. The coastline of Chile not only suffers from coastal hypoxia but the cold, oxygen-poor waters in upwelling events are also supersaturated in CO2, a study site to explore the combined effect of OA and hypoxia. We experimentally evaluated the metabolic response of different invertebrate species (2 anthozoans, 9 molluscs, 4 crustaceans, 2 echinoderms) of the coastline of central Chile (33°30′S, 71°37′W) to hypoxia and OA within predicted levels and in a full factorial design. Organisms were exposed to 4 different treatments (ambient, low oxygen, high CO2, and the combination of low oxygen and high CO2) and metabolism was measured after 3 and 6 days. We show that the combination of hypoxia and increased pCO2 reduces the respiration significantly, compared to a single stressor. The evaluation of synergistic pressures, a more realistic scenario than single stressors, is crucial to evaluate the effect of future changes for coastal species and our results provide the first insight on what might happen in the next 100 years.

Prodrugs designed to discriminate pathological (tumour) and physiological (normal tissue) hypoxia

International Nuclear Information System (INIS)

Wilson, W.R.; Patterson, A.V.

2003-01-01

There is now abundant evidence that hypoxic contributes to treatment failure in radiation therapy. As a target for therapeutic intervention, hypoxia is especially attractive because it is a common feature of most human tumours and therefore a potential 'pan target' across many tumour types. However, attempts to exploit hypoxia face the problem that oxygen concentrations in some normal tissues are also heterogeneous and that O 2 distributions in tumours and normal tissues overlap. Simply adjusting the K value (O 2 concentration for 50% inhibition of activation) does not provide a satisfactory solution. Bioreductive drugs like tirapazamine with high K values are activated significantly in several normal tissues, while nitro compounds and quinones with low K values spare the hypoxic tumour cells at 'intermediate' O 2 tensions (1-10 mM O 2 ) which are considered to be major contributors to tumour radioresistance. A potential strategy for overcoming this dilemma is to design prodrugs that are activated only at very low K values, but give relatively stable cytotoxic metabolites capable of diffusing to cells at higher O 2 concentrations. This approach redefines the therapeutic target as cells adjacent to zones of pathological hypoxia ( 2 ), providing discrimination from physiological hypoxia in normal tissues. Detecting bioreductive prodrugs capable of providing bystander killing of this kind is not straightforward. We have adapted a multicellular layer (MCL) co-culture model for quantifying bystander effects in GDEPT (Wilson et al., Cancer Res., 62: 1425-1432, 2002), and have used this to measure bystander effects of hypoxia-activated prodrugs. This model uses differences in metabolic activation of bioreductive drugs between A459 cell lines with low and high cytochrome P450 reductase activity, rather than O 2 gradients, to effect localised prodrug activation. It shows that TPZ and the nitroimidazole RSU-1069 have little or no bystander effect, but that dinitrobenzamide

Quercetin suppresses hypoxia-induced accumulation of hypoxia-inducible factor-1alpha (HIF-1alpha) through inhibiting protein synthesis.

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Lee, Dae-Hee; Lee, Yong J

2008-10-01

Quercetin, a ubiquitous bioactive plant flavonoid, has been shown to inhibit the proliferation of cancer cells and induce the accumulation of hypoxia-inducible factor-1alpha (HIF-1alpha) in normoxia. In this study, under hypoxic conditions (1% O(2)), we examined the effect of quercetin on the intracellular level of HIF-1alpha and extracellular level of vascular endothelial growth factor (VEGF) in a variety of human cancer cell lines. Surprisingly, we observed that quercetin suppressed the HIF-1alpha accumulation during hypoxia in human prostate cancer LNCaP, colon cancer CX-1, and breast cancer SkBr3 cells. Quercetin treatment also significantly reduced hypoxia-induced secretion of VEGF. Suppression of HIF-1alpha accumulation during treatment with quercetin in hypoxia was not prevented by treatment with 26S proteasome inhibitor MG132 or PI3K inhibitor LY294002. Interestingly, hypoxia (1% O(2)) in the presence of 100 microM quercetin inhibited protein synthesis by 94% during incubation for 8 h. Significant quercetin concentration-dependent inhibition of protein synthesis and suppression of HIF-1alpha accumulation were observed under hypoxic conditions. Treatment with 100 microM cycloheximide, a protein synthesis inhibitor, replicated the effect of quercetin by inhibiting HIF-1alpha accumulation during hypoxia. These results suggest that suppression of HIF-1alpha accumulation during treatment with quercetin under hypoxic conditions is due to inhibition of protein synthesis. (c) 2008 Wiley-Liss, Inc.

Protective effect of astrocyte-conditioned medium on neurons following hypoxia and mechanical injury

Directory of Open Access Journals (Sweden)

YAN Ji-wen

2013-02-01

Full Text Available 【Abstract】Objective: To investigate the protec-tive effect of mouse astrocyte-conditioned medium (ACM on hypoxic and mechanically injured neurons by a cell model in vitro, and to explore the possible mechanism. Methods: The model of hypoxic neuronal injury was caused by 3% O 2 in three-gas incubator. Neurons were cul-tured with ordinary medium or 20% ACM respectively and randomly divided into hypoxic group (hypoxia for 4, 8, 24 h and marked as H4R0, H8R0, H24R0 and hypoxia reoxygenation group (H4R24, H8R24, H24R24. Mechanical injury model was developed by scratching neurons cultured in 20% ACM or ordinary medium to different degrees. Neu-rons in both medium were divided into normal control group, mild, moderate and severe injury groups. The 20% ACM was added 24 h before hypoxia/reoxygenation or mechanical injury. The morphology and survival of neurons were observed and counted by trypan blue staining. The concentration of NO, lactic dehydrogenase (LDH and membrane ATPase activity were detected by corresponding kits. Results: It was showed that 20% ACM can obviously promote the survival rate of hypoxia/reoxygenated neurons and scratched neurons as well. The morphology and num-ber of neurons exposed to hypoxia or scratch injury showed great difference between groups with or without ACM treatment. Compared with control group, the concentration of NO and LDH was much lower in hypoxic/reoxygenated neurons treated with 20% ACM, and the ATPase activity was higher. For the mechanical injury model, neurons with moderate injury also revealed a lower NO and LDH concen-tration than the control group. All the differences were sta-tistically significant (P<0.05. Conclusion: ACM can promote the survival and func-tional recovery of neurons following hypoxia or scratching to a certain degree. The mechanism may be associated with reducing the synthesis and release of NO and LDH as well as increasing the activity of membrane ATPase. Key words: Glial cell line

Acetazolamide during acute hypoxia improves tissue oxygenation in the human brain.

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Wang, Kang; Smith, Zachary M; Buxton, Richard B; Swenson, Erik R; Dubowitz, David J

2015-12-15

Low doses of the carbonic anhydrase inhibitor acetazolamide provides accelerated acclimatization to high-altitude hypoxia and prevention of cerebral and other symptoms of acute mountain sickness. We previously observed increases in cerebral O2 metabolism (CMRO2 ) during hypoxia. In this study, we investigate whether low-dose oral acetazolamide (250 mg) reduces this elevated CMRO2 and in turn might improve cerebral tissue oxygenation (PtiO2 ) during acute hypoxia. Six normal human subjects were exposed to 6 h of normobaric hypoxia with and without acetazolamide prophylaxis. We determined CMRO2 and cerebral PtiO2 from MRI measurements of cerebral blood flow (CBF) and cerebral venous O2 saturation. During normoxia, low-dose acetazolamide resulted in no significant change in CBF, CMRO2 , or PtiO2 . During hypoxia, we observed increases in CBF [48.5 (SD 12.4) (normoxia) to 65.5 (20.4) ml·100 ml(-1)·min(-1) (hypoxia), P effect was improved cerebral tissue PtiO2 during acute hypoxia [11.4 (2.7) (hypoxia) to 16.5 (3.0) mmHg (hypoxia + acetazolamide), P effect, low-dose acetazolamide is effective at the capillary endothelium, and we hypothesize that local interruption in cerebral CO2 excretion accounts for the improvements in CMRO2 and ultimately in cerebral tissue oxygenation during hypoxia. This study suggests a potentially pivotal role of cerebral CO2 and pH in modulating CMRO2 and PtiO2 during acute hypoxia. Copyright © 2015 the American Physiological Society.

Effect of hypoxia on tissue factor pathway inhibitor expression in breast cancer.

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Cui, X Y; Tinholt, M; Stavik, B; Dahm, A E A; Kanse, S; Jin, Y; Seidl, S; Sahlberg, K K; Iversen, N; Skretting, G; Sandset, P M

2016-02-01

ESSENTIALS: A hypoxic microenvironment is a common feature of tumors that may influence activation of coagulation. MCF-7 and SK-BR-3 breast cancer cells and breast cancer tissue samples were used. The results showed transcriptional repression of tissue factor pathway inhibitor expression in hypoxia. Hypoxia-inducible factor 1α may be a target for the therapy of cancer-related coagulation and thrombosis. Activation of coagulation is a common finding in patients with cancer, and is associated with an increased risk of venous thrombosis. As a hypoxic microenvironment is a common feature of solid tumors, we investigated the role of hypoxia in the regulation of tissue factor (TF) pathway inhibitor (TFPI) expression in breast cancer. To explore the transcriptional regulation of TFPI by hypoxia-inducible factor (HIF)-1α in breast cancer cells and their correlation in breast cancer tissues. MCF-7 and SK-BR-3 breast cancer cells were cultured in 1% oxygen or treated with cobalt chloride (CoCl2 ) to mimic hypoxia. Time-dependent and dose-dependent downregulation of TFPI mRNA (quantitative RT-PCR) and of free TFPI protein (ELISA) were observed in hypoxia. Western blotting showed parallel increases in the levels of HIF-1α protein and TF. HIF-1α inhibitor abolished or attenuated the hypoxia-induced downregulation of TFPI. Luciferase reporter assay showed that both hypoxia and HIF-1α overexpression caused strong repression of TFPI promoter activity. Subsequent chromatin immunoprecipitation and mutagenesis analysis demonstrated a functional hypoxia response element within the TFPI promoter, located at -1065 to -1060 relative to the transcriptional start point. In breast cancer tissue samples, gene expression analyses showed a positive correlation between the mRNA expression of TFPI and that of HIF-1α. This study demonstrates that HIF-1α is involved in the transcriptional regulation of the TFPI gene, and suggests that a hypoxic microenvironment inside a breast tumor may

Hypoxia and acidification in ocean ecosystems: coupled dynamics and effects on marine life.

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Gobler, Christopher J; Baumann, Hannes

2016-05-01

There is increasing recognition that low dissolved oxygen (DO) and low pH conditions co-occur in many coastal and open ocean environments. Within temperate ecosystems, these conditions not only develop seasonally as temperatures rise and metabolic rates accelerate, but can also display strong diurnal variability, especially in shallow systems where photosynthetic rates ameliorate hypoxia and acidification by day. Despite the widespread, global co-occurrence of low pH and low DO and the likelihood that these conditions may negatively impact marine life, very few studies have actually assessed the extent to which the combination of both stressors elicits additive, synergistic or antagonistic effects in marine organisms. We review the evidence from published factorial experiments that used static and/or fluctuating pH and DO levels to examine different traits (e.g. survival, growth, metabolism), life stages and species across a broad taxonomic spectrum. Additive negative effects of combined low pH and low DO appear to be most common; however, synergistic negative effects have also been observed. Neither the occurrence nor the strength of these synergistic impacts is currently predictable, and therefore, the true threat of concurrent acidification and hypoxia to marine food webs and fisheries is still not fully understood. Addressing this knowledge gap will require an expansion of multi-stressor approaches in experimental and field studies, and the development of a predictive framework. In consideration of marine policy, we note that DO criteria in coastal waters have been developed without consideration of concurrent pH levels. Given the persistence of concurrent low pH-low DO conditions in estuaries and the increased mortality experienced by fish and bivalves under concurrent acidification and hypoxia compared with hypoxia alone, we conclude that such DO criteria may leave coastal fisheries more vulnerable to population reductions than previously anticipated. © 2016

Systemic administration of thrombin peptide TP508 enhances VEGF-stimulated angiogenesis and attenuates effects of chronic hypoxia

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Olszewska-Pazdrak, Barbara; Carney, Darrell H.

2015-01-01

Revascularization of chronic wounds and ischemic tissue is attenuated by endothelial dysfunction and the inability of angiogenic factors to stimulate angiogenesis. We recently showed that TP508, a nonproteolytic thrombin peptide, increases perfusion and NO-dependent vasodilation in hearts with chronic ischemia and stimulates NO production by endothelial cells. In this study, we investigated systemic in vivo effects of TP508 on VEGF-stimulated angiogenesis in vitro using aortic explants in normoxic and hypoxic conditions. Mice were injected with saline or TP508 and 24h later aortas were removed and cultured to quantify endothelial sprouting. TP508 injection increased endothelial sprouting and potentiated the in vitro response to VEGF. Exposure of control explants to hypoxia inhibited basal and VEGF-stimulated endothelial cell sprouting. This effect of hypoxia was significantly prevented by TP508 injection. Thus, TP508 systemic administration increases responsiveness of aortic endothelial cells to VEGF and diminishes the effect of chronic hypoxia on endothelial cell sprouting. Studies using human endothelial cells in culture suggest that protective effects of TP508 during hypoxia may involve stimulation of endothelial cell NO production. These data suggest potential clinical benefit of using a combination of systemic TP508 and local VEGF as a therapy for revascularization of ischemic tissue. PMID:23594718

Hypoxia and anemia: factors in decreased sensitivity to radiation therapy and chemotherapy?

Science.gov (United States)

Harrison, Louis; Blackwell, Kimberly

2004-01-01

Hypoxia is a common feature of solid tumors that occurs across a wide variety of malignancies. Hypoxia and anemia (which contributes to tumor hypoxia) can lead to ionizing radiation and chemotherapy resistance by depriving tumor cells of the oxygen essential for the cytotoxic activities of these agents. Hypoxia may also reduce tumor sensitivity to radiation therapy and chemotherapy through one or more indirect mechanisms that include proteomic and genomic changes. These effects, in turn, can lead to increased invasiveness and metastatic potential, loss of apoptosis, and chaotic angiogenesis, thereby further increasing treatment resistance. Investigations of the prognostic significance of pretreatment tumor oxygenation status have shown that hypoxia (oxygen tension [pO(2)] value effect of hypoxia on standard cancer treatment, a variety of hypoxia- and anemia-targeted therapies have been studied in an effort to improve therapeutic effectiveness and patient outcomes. Early evidence from experimental and clinical studies suggests the administration of recombinant human erythropoietin (rHuEPO) may enhance the effectiveness of radiation therapy and chemotherapy by increasing hemoglobin levels and ameliorating anemia in patients with disease- or treatment-related anemia. However, further research is needed in the area of hypoxia-related treatment resistance and its reversal.

Effects of simulated altitude (normobaric hypoxia on cardiorespiratory parameters and circulating endothelial precursors in healthy subjects

Directory of Open Access Journals (Sweden)

Pierini Alberto

2007-08-01

Full Text Available Abstract Background Circulating Endothelial Precursors (PB-EPCs are involved in the maintenance of the endothelial compartment being promptly mobilized after injuries of the vascular endothelium, but the effects of a brief normobaric hypoxia on PB-EPCs in healthy subjects are scarcely studied. Methods Clinical and molecular parameters were investigated in healthy subjects (n = 8 in basal conditions (T0 and after 1 h of normobaric hypoxia (T1, with Inspiratory Fraction of Oxygen set at 11.2% simulating 4850 mt of altitude. Blood samples were obtained at T0 and T1, as well as 7 days after hypoxia (T2. Results In all studied subjects we observed a prompt and significant increase in PB-EPCs, with a return to basal value at T2. The induction of hypoxia was confirmed by Alveolar Oxygen Partial Pressure (PAO2 and Spot Oxygen Saturation decreases. Heart rate increased, but arterial pressure and respiratory response were unaffected. The change in PB-EPCs percent from T0 to T1 was inversely related to PAO2 at T1. Rapid (T1 increases in serum levels of hepatocyte growth factor and erythropoietin, as well as in cellular PB-EPCs-expression of Hypoxia Inducible Factor-1α were observed. Conclusion In conclusion, the endothelial compartment seems quite responsive to standardized brief hypoxia, possibly important for PB-EPCs activation and recruitment.

Hypoxia in the changing marine environment

International Nuclear Information System (INIS)

Zhang, J; Cowie, G; Naqvi, S W A

2013-01-01

The predicted future of the global marine environment, as a combined result of forcing due to climate change (e.g. warming and acidification) and other anthropogenic perturbation (e.g. eutrophication), presents a challenge to the sustainability of ecosystems from tropics to high latitudes. Among the various associated phenomena of ecosystem deterioration, hypoxia can cause serious problems in coastal areas as well as oxygen minimum zones in the open ocean (Diaz and Rosenberg 2008 Science 321 926–9, Stramma et al 2008 Science 320 655–8). The negative impacts of hypoxia include changes in populations of marine organisms, such as large-scale mortality and behavioral responses, as well as variations of species distributions, biodiversity, physiological stress, and other sub-lethal effects (e.g. growth and reproduction). Social and economic activities that are related to services provided by the marine ecosystems, such as tourism and fisheries, can be negatively affected by the aesthetic outcomes as well as perceived or real impacts on seafood quality (STAP 2011 (Washington, DC: Global Environment Facility) p 88). Moreover, low oxygen concentration in marine waters can have considerable feedbacks to other compartments of the Earth system, like the emission of greenhouse gases to the atmosphere, and can affect the global biogeochemical cycles of nutrients and trace elements. It is of critical importance to prediction and adaptation strategies that the key processes of hypoxia in marine environments be precisely determined and understood (cf Zhang et al 2010 Biogeosciences 7 1–24). (synthesis and review)

Protective effect of Edaravone against hypoxia-induced cytotoxicity in osteoblasts MC3T3-E1 cells.

Science.gov (United States)

Cao, Bo; Chai, Chunxiang; Zhao, Sishun

2015-12-01

Edaravone is a newly developed clinical medicine for the treatment of acute cerebral infarction. Reduced blood supply to bones (hypoxia) has been involved in the pathological development of osteoporosis. In this study, we investigated the effect of Edaravone and its latent mechanism on hypoxia-induced cell toxicity in MC3T3-E1 cells. Cell viability was determined by the 3-(4,5-dimethyl-thiazol-2yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Intracellular reactive oxygen species (ROS) and nitric oxide (NO) were determined by the fluorescence dyes 2',7'-dichlorofluorescein diacetate (DCFH-DA) and 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM DA), respectively. mRNA and proteins were determined by real-time polymerase chain reaction and Western blot analysis, respectively. Edaravone significantly restored the hypoxia-induced reduction of MC3T3-E1 cell viability and inhibited lactate dehydrogenase release. In addition, we found that Edaravone inhibits the generation of ROS and NO. Hoechst staining results indicated that the nuclear condensation characteristic of apoptosis was increased in MC3T3-E1 cells after hypoxia exposure, which was significantly suppressed by Edaravone treatment. Mechanistically, we found that Edaravone markedly reduced the expression of cleaved caspase-3 and blunted the release of cytochrome c. These findings strongly suggested that Edaravone suppresses hypoxia-induced cytotoxicity in MC3T3-E1 cells. The pleiotropic effects of Edaravone on hypoxia exposure in osteoblasts suggest potential antiosteoporosis mechanisms of Edaravone. © 2015 International Union of Biochemistry and Molecular Biology.

Effect of ovariectomy on inflammation induced by intermittent hypoxia in a mouse model of sleep apnea.

Science.gov (United States)

Torres, Marta; Palomer, Xavier; Montserrat, Josep M; Vázquez-Carrera, Manel; Farré, Ramon

2014-10-01

Patient data report marked gender and pre-vs-postmenopausal differences in obstructive sleep apnea (OSA). However, no experimental data are available on how sexual hormones modulate OSA consequences. Here we report novel results on estrogen-modulated heart and brain inflammation in female mice subjected to intermittent hypoxia, a major injurious challenge in OSA. C57BL/6J (14-week old) intact and ovariectomized mice (n=6 each) were subjected to intermittent hypoxia (20 s at 5% and 40s at 21%, 60 cycles/h; 6 h/day). Identical intact and ovariectomized groups breathing room air were controls. After 30 days, the gene expressions of interleukins 6 and 8 (IL-6, IL-8) in the brain and heart tissues were measured. Whereas, compared with normoxia, intermittent hypoxia considerably increased IL-6 and IL-8 gene expressions in intact females, no change was found in ovariectomized mice when comparing normoxia and intermittent hypoxia. These data suggest that estrogens modulate the inflammatory effects of intermittent hypoxia and point to further studies on the role played by sex hormones in OSA. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of continuous hypoxia on energy metabolism in cultured cerebro-cortical neurons.

Science.gov (United States)

Malthankar-Phatak, Gauri H; Patel, Anant B; Xia, Ying; Hong, Soonsun; Chowdhury, Golam M I; Behar, Kevin L; Orina, Isaac A; Lai, James C K

2008-09-10

Mechanisms underlying hypoxia-induced neuronal adaptation have not been fully elucidated. In the present study we investigated glucose metabolism and the activities of glycolytic and TCA cycle enzymes in cerebro-cortical neurons exposed to hypoxia (3 days in 1% of O2) or normoxia (room air). Hypoxia led to increased activities of LDH (194%), PK (90%), and HK (24%) and decreased activities of CS (15%) and GDH (34%). Neurons were incubated with [1-(13)C]glucose for 45 and 120 min under normoxic or hypoxic (120 min only) conditions and 13C enrichment determined in the medium and cell extract using 1H-{13C}-NMR. In hypoxia-treated neurons [3-(13)C]lactate release into the medium was 428% greater than in normoxia-treated controls (45-min normoxic incubation) and total flux through lactate was increased by 425%. In contrast glucose oxidation was reduced significantly in hypoxia-treated neurons, even when expressed relative to total cellular protein, which correlated with the reduced activities of the measured mitochondrial enzymes. The results suggest that surviving neurons adapt to prolonged hypoxia by up-regulation of glycolysis and down-regulation of oxidative energy metabolism, similar to certain other cell types. The factors leading to adaptation and survival for some neurons but not others remain to be determined.

The pressure exerted by a confined ideal gas

International Nuclear Information System (INIS)

Pang Hai; Dai Wusheng; Xie Mi

2011-01-01

In this paper, we study the pressure exerted by a confined ideal gas on the container boundary and we introduce a surface force in gases. First, the general expression for the local surface pressure tensor is obtained. We find, by examples, that the pressure vanishes at the edges of a box, peaks at the middle of the surface and its magnitude for different statistics satisfies p Fermi > p classical > p Bose on every boundary point. Then, the relation between the surface pressure tensor and generalized forces is studied. Based on the relation, we find that a confined ideal gas can exert forces whose effect is to reduce the total surface area of the boundary of an incompressible object. The force provides mechanisms for several mechanical effects. (1) The force contributes to the adhesion of two thin films in contact with each other. We derive an expression for the adhesion force between two square sheets, estimate its magnitude, and also give a method for distinguishing it from other adhesion forces. (2) The force can lead to the recoiling of a DNA-like column. We study the recoiling process using a simple model and find a deviation from the result given in the thermodynamic limit, which is in accordance with experiments. (3) An open container immersed in a gas can be compressed by this force like the Casimir effect. We discuss the effect for various geometries. (paper)

The effect of aprotinin on hypoxia-reoxygenation-induced changes in neutrophil and endothelial function.

LENUS (Irish Health Repository)

Harmon, D

2012-02-03

BACKGROUND AND OBJECTIVE: An acute inflammatory response associated with cerebral ischaemia-reperfusion contributes to the development of brain injury. Aprotinin has potential, though unexplained, neuroprotective effects in patients undergoing cardiac surgery. METHODS: Human neutrophil CD11 b\\/CD18, endothelial cell intercellular adhesion molecule-1 (ICAM-1) expression and endothelial interleukin (IL)-1beta supernatant concentrations in response to in vitro hypoxia-reoxygenation was studied in the presence or absence of aprotinin (1600 KIU mL(-1)). Adhesion molecule expression was quantified using flow cytometry and IL-1beta concentrations by enzyme-linked immunosorbent assay. Data were analysed using ANOVA and post hoc Student-Newman-Keuls test as appropriate. RESULTS: Exposure to 60-min hypoxia increased neutrophil CD11b expression compared to normoxia (170+\\/-46% vs. 91+\\/-27%, P = 0.001) (percent intensity of fluorescence compared to time 0) (n = 8). Hypoxia (60 min) produced greater upregulation of CD11b expression in controls compared to aprotinin-treated neutrophils [(170+\\/-46% vs. 129+\\/-40%) (P = 0.04)] (n = 8). Hypoxia-reoxygenation increased endothelial cell ICAM-1 expression (155+\\/-3.7 vs. 43+\\/-21 mean channel fluorescence, P = 0.0003) and IL-1beta supernatant concentrations compared to normoxia (3.4+\\/-0.4 vs. 2.6+\\/-0.2, P = 0.02) (n = 3). Hypoxia-reoxygenation produced greater upregulation of ICAM- 1 expression [(155+\\/-3.3 vs. 116+\\/-0.7) (P = 0.001)] and IL-1beta supernatant concentrations [(3.4+\\/-0.3 vs. 2.6+\\/-0.1) (P = 0.01)] in controls compared to aprotinin-treated endothelial cell preparation (n = 3). CONCLUSIONS: Hypoxia-reoxygenation-induced upregulation of neutrophil CD11b, endothelial cell ICAM-1 expression and IL-1beta concentrations is decreased by aprotinin at clinically relevant concentrations.

Tissue hypoxia during ischemic stroke: adaptive clues from hypoxia-tolerant animal models.

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Nathaniel, Thomas I; Williams-Hernandez, Ashley; Hunter, Anan L; Liddy, Caroline; Peffley, Dennis M; Umesiri, Francis E; Imeh-Nathaniel, Adebobola

2015-05-01

The treatment and prevention of hypoxic/ischemic brain injury in stroke patients remain a severe and global medical issue. Numerous clinical studies have resulted in a failure to develop chemical neuroprotection for acute, ischemic stroke. Over 150 estimated clinical trials of ischemic stroke treatments have been done, and more than 200 drugs and combinations of drugs for ischemic and hemorrhagic strokes have been developed. Billions of dollars have been invested for new scientific breakthroughs with only limited success. The revascularization of occluded cerebral arteries such as anti-clot treatments of thrombolysis has proven effective, but it can only be used in a 3-4.5h time frame after the onset of a stroke, and not for every patient. This review is about novel insights on how to resist tissue hypoxia from unconventional animal models. Ability to resist tissue hypoxia is an extraordinary ability that is not common in many laboratory animals such as rat and mouse models. For example, we can learn from a naked mole-rat, Chrysemys picta, how to actively regulate brain metabolic activity to defend the brain against fluctuating oxygen tension and acute bouts of oxidative stress following the onset of a stroke. Additionally, a euthermic arctic ground squirrel can teach us how the brain of a stroke patient can remain well oxygenated during tissue hypoxia with no evidence of cellular stress. In this review, we discuss how these animals provide us with a system to gain insight into the possible mechanisms of tissue hypoxia/ischemia. This issue is of clinical significance to stroke patients. We describe specific physiological and molecular adaptations employed by different animals' models of hypoxia tolerance in aquatic and terrestrial environments. We highlight how these adaptations might provide potential clues on strategies to adapt for the clinical management of tissue hypoxia during conditions such as stroke where oxygen demand fails to match the supply. Copyright

Hypoxia symptoms during altitude training in professional Iranian fighter pilots.

Science.gov (United States)

Alagha, Babak; AhmadBeygi, Shervin; Ahmadbeigy, Shervin; Moosavi, Seyed Ali Javad; Jalali, Seyed Mahmood

2012-01-01

Susceptibility to hypoxia is influenced by a multitude of factors, including fatigue, physical activity, illnesses, ambient temperature, rate of ascent, destination altitude, medications, and alcohol. Anecdotally, several reports have been made regarding changes in the form of hypoxia presentation in Iranian fighter pilots in the absence of these factors. This study focused specifically on the effect of pilot age on susceptibility to hypoxia and its initial presentation. We assumed that a pilot's age may increase his susceptibility to hypoxia and consequently reduce the amount of time it takes for hypoxia to present. Because our literature review did not reveal any previous study addressing the possible relationship between age and susceptibility to hypoxia, the purpose of this study is to address and clarify this relationship. In this retrospective study, we collected information from Iranian fighter pilots (n = 30) through an anonymous questionnaire in 2000. The form of hypoxia presentation of each subject was evaluated during five altitude chamber training (ACT) sessions that were conducted routinely from 1972 to 1984. To enhance the accuracy of the study's results, confounding factors such as prior hypoxia experience in an ACT session have been taken into consideration. The results revealed a statistically significant relationship between age and a change in the form of hypoxia presentation in our subjects. Increased age reduced the amount of time before the first individual hypoxia symptom appeared (P < .000002). Although having previous hypoxia experience may help pilots to recognize their symptoms earlier, its effect was not statistically significant (P < .18). A few changes in the nature of individual symptoms were observed; however, we did not find a meaningful statistical correlation between pilot age and change in the nature of symptoms. Susceptibility ot hypoxia increases with pilot age. Copyright © 2012 Air Medical Journal Associates. Published by

The role of GABA in the hypoxia tolerance of the epaulette shark

International Nuclear Information System (INIS)

Wise, G.; Mulvey, J.; Renshaw, G.M.C.; Dodd, P.R.

1998-01-01

Full text: The epaulette shark responds to hypoxia with brain hypometabolism which is correlated with increased levels of gamma-aminobutyric acid (GABA). We examined GABA-like immunoreactivity (GABA-IR) and the density and binding characteristics of GABA A receptors in the Epaulette shark brainstem. These studies were conducted to investigate changes in response to hypoxia. Experimental animals were exposed to eight cycles of an extreme hypoxic regimen (5% of normoxia). Animals were anaesthetised with 80mg/L of MS222 and the brain was dissected and processed either for immunohistochemistry or receptor ligand binding. Membranes were prepared at 4 deg C according to a previously reported protocol and the binding characteristics of [ 3 H]flunitrazeparn ([ 3 H]FNZ) were examined using an in vitro centrifugation assay. We report on the effect of hypoxia on specific [ 3 H]FNZ binding characteristics. GABA-IR was detected using a primary antibody dilution of 1:15 000 and the Vector ABC method. We report that an overall increase in the optical density of GABA-IR occurs with significant increases in three out of the four brainstem nuclei examined in experimental animals. The results of these studies are discussed in conjunction with the hypoxia-tolerance .of the epaulette shark. Copyright (1998) Australian Neuroscience Society

Effect of all-trans retinoic acid treatment on prohibitin and renin-angiotensin-aldosterone system expression in hypoxia-induced renal tubular epithelial cell injury.

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Zhou, Tian-Biao; Ou, Chao; Rong, Liang; Drummen, Gregor P C

2014-09-01

All-trans retinoic acid (ATRA) exerts various effects on physiological processes such as cell growth, differentiation, apoptosis and inflammation. Prohibitins (PHB), including prohibitin 1 (PHB1) and prohibitin 2 (PHB2), are evolutionary conserved and pleiotropic proteins implicated in various cellular functions, including proliferation, tumor suppression, apoptosis, transcription, and mitochondrial protein folding. The renin-angiotensin-aldosterone system plays a pivotal role in the regulation of blood pressure and volume homeostasis. All these factors and systems have been implicated in renal interstitial fibrosis. Therefore, the objective of this study was to investigate the effect of ATRA treatment on the renin-angiotensin-aldosterone system and expression of prohibitins to further understand its role in the processes leading to renal interstitial fibrosis. The hypoxic and oxidative stress conditions in obstructive renal disease were simulated in a hypoxia/reoxygenation model with renal tubular epithelial cells (RTEC) as a model system. Subsequently, the effect of ATRA on mRNA and protein expression levels was determined and correlations were established between factors involved in the renin-angiotensin-aldosterone system, the prohibitins, cellular redox status, renal interstitial fibrosis and ATRA treatment. Correlation analysis showed that both PHB1 and PHB2 protein levels were negatively correlated with angiotensin I, ACE1, angiotensin II, TGF-β1, Col-IV, FN, ROS, and MDA (PHB1: r = -0.792, -0.834, -0.805, -0.795, -0.778, -0.798, -0.751, -0.682; PHB2: r = -0.872, -0.799, -0.838, -0.773, -0.769, -0.841, -0.794, -0.826; each p system under hypoxia/reoxygenation conditions. © The Author(s) 2014.

Brain blood flow and blood pressure during hypoxia in the epaulette shark Hemiscyllium ocellatum, a hypoxia-tolerant elasmobranch.

Science.gov (United States)

Söderström, V; Renshaw, G M; Nilsson, G E

1999-04-01

The key to surviving hypoxia is to protect the brain from energy depletion. The epaulette shark (Hemiscyllium ocellatum) is an elasmobranch able to resist energy depletion and to survive hypoxia. Using epi-illumination microscopy in vivo to observe cerebral blood flow velocity on the brain surface, we show that cerebral blood flow in the epaulette shark is unaffected by 2 h of severe hypoxia (0.35 mg O2 l-1 in the respiratory water, 24 C). Thus, the epaulette shark differs from other hypoxia- and anoxia-tolerant species studied: there is no adenosine-mediated increase in cerebral blood flow such as that occurring in freshwater turtles and cyprinid fish. However, blood pressure showed a 50 % decrease in the epaulette shark during hypoxia, indicating that a compensatory cerebral vasodilatation occurs to maintain cerebral blood flow. We observed an increase in cerebral blood flow velocity when superfusing the normoxic brain with adenosine (making sharks the oldest vertebrate group in which this mechanism has been found). The adenosine-induced increase in cerebral blood flow velocity was reduced by the adenosine receptor antagonist aminophylline. Aminophylline had no effect upon the maintenance of cerebral blood flow during hypoxia, however, indicating that adenosine is not involved in maintaining cerebral blood flow in the epaulette shark during hypoxic hypotension.

The role of hypoxia inducible factor 1 (HIF-1) in hypoxia induced apoptosis

NARCIS (Netherlands)

Greijer, A.E.; Wall, E. van der

2004-01-01

Apoptosis can be induced in response to hypoxia. The severity of hypoxia determines whether cells become apoptotic or adapt to hypoxia and survive. A hypoxic environment devoid of nutrients prevents the cell undergoing energy dependent apoptosis and cells become necrotic. Apoptosis regulatory

Moderate hypoxia influences potassium outward currents in adipose-derived stem cells.

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Mayuri Prasad

Full Text Available Moderate hypoxic preconditioning of adipose-derived stem cells (ASCs enhances properties such as proliferation and secretion of growth factors, representing a valuable strategy to increase the efficiency of cell-based therapies. In a wide variety of cells potassium (K+ channels are key elements involved in the cellular responses to hypoxia, suggesting that ASCs cultured under low oxygen conditions may display altered electrophysiological properties. Here, the effects of moderate hypoxic culture on proliferation, whole-cell currents, and ion channel expression were investigated using human ASCs cultured at 5% and 20% oxygen. Although cell proliferation was greatly enhanced, the dose-dependent growth inhibition by the K+ channel blocker tetraethylammonium (TEA was not significantly affected by hypoxia. Under both normoxic and hypoxic conditions, ASCs displayed outward K+ currents composed by Ca2+-activated, delayed rectifier, and transient components. Hypoxic culture reduced the slope of the current-voltage curves and caused a negative shift in the voltage activation threshold of the whole-cell currents. However, the TEA-mediated shift of voltage activation threshold was not affected by hypoxia. Semiquantitative real-time RT-PCR revealed that expression of genes encoding for various ion channels subunits related to oxygen sensing and proliferation remained unchanged after hypoxic culture. In conclusion, outward currents are influenced by moderate hypoxia in ASCs through a mechanism that is not likely the result of modulation of TEA-sensitive K+ channels.

Effect of hypoxia-inducible factor 1-alpha (HIF-1α) on proliferation ...

African Journals Online (AJOL)

Jane

2011-07-25

Jul 25, 2011 ... Full Length Research Paper. Effect of hypoxia-inducible factor 1-alpha ... 1Department of Neurosurgery, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai 200025,. China. 2Department of Neurosurgery, Chaoyang Hospital, Huainan, Anhui, China. 3Department of Neurosurgery ...

Hypoxia-inducible factor-1α upregulation in microglia following hypoxia protects against ischemia-induced cerebral infarction.

Science.gov (United States)

Huang, Tao; Huang, Weiyi; Zhang, Zhiqiang; Yu, Lei; Xie, Caijun; Zhu, Dongan; Peng, Zizhuang; Chen, Jiehan

2014-10-01

Activated microglia were considered to be the toxic inflammatory mediators that induce neuron degeneration after brain ischemia. Hypoxia can enhance the expression of hypoxia-inducible factor-1α (HIF-1α) in microglia and cause microglial activation. However, intermittent hypoxia has been reported recently to be capable of protecting the body from myocardial ischemia. We established a high-altitude environment as the hypoxic condition in this study. The hypoxic condition displayed a neuroprotective effect after brain ischemia, and mice exposed to this condition presented better neurological performance and smaller infarct size. At the same time, a high level of HIF-1α, low level of isoform of nitric oxide synthase, and a reduction in microglial activation were also seen in ischemic focus of hypoxic mice. However, this neuroprotective effect could be blocked by 2-methoxyestradiol, the HIF-1α inhibitor. Our finding suggested that HIF-1α expression was involved in microglial activation in vitro and was regulated by oxygen supply. The microglia were inactivated by re-exposure to hypoxia, which might be due to overexpression of HIF-1α. These results indicated that hypoxic conditions can be exploited to achieve maximum neuroprotection after brain ischemia. This mechanism possibly lies in microglial inactivation through regulation of the expression of HIF-1α.

Hypoxia as a biomarker for radioresistant cancer stem cells.

Science.gov (United States)

Peitzsch, Claudia; Perrin, Rosalind; Hill, Richard P; Dubrovska, Anna; Kurth, Ina

2014-08-01

Tumor initiation, growth and relapse after therapy are thought to be driven by a population of cells with stem cell characteristics, named cancer stem cells (CSC). The regulation of their radiation resistance and their maintenance is poorly understood. CSC are believed to reside preferentially in special microenvironmental niches located within tumor tissues. The features of these niches are of crucial importance for CSC self-renewal, metastatic potential and therapy resistance. One of the characteristics of solid tumors is occurrence of less oxygenated (hypoxic regions), which are believed to serve as so-called hypoxic niches for CSC. The purpose of this review was the critical discussion of the supportive role of hypoxia and hypoxia-related pathways during cancer progression and radiotherapy resistance and the relevance for therapeutic implications in the clinic. It is generally known since decades that hypoxia inside solid tumors impedes chemo- and radiotherapy. However, there is limited evidence to date that targeting hypoxic regions during conventional therapy is effective. Nonetheless improved hypoxia-imaging technologies and image guided individualized hypoxia targeted therapy in conjunction with the development of novel molecular targets may be able to challenge the protective effect on the tumor provided by hypoxia.

Induction of Gastrin Expression in Gastrointestinal Cells by Hypoxia or Cobalt Is Independent of Hypoxia-Inducible Factor (HIF)

OpenAIRE

Xiao, Lin; Kovac, Suzana; Chang, Mike; Shulkes, Arthur; Baldwin, Graham S.; Patel, Oneel

2012-01-01

Gastrin and its precursors have been shown to promote mitogenesis and angiogenesis in gastrointestinal tumors. Hypoxia stimulates tumor growth, but its effect on gastrin gene regulation has not been examined in detail. Here we have investigated the effect of hypoxia on the transcription of the gastrin gene in human gastric cancer (AGS) cells. Gastrin mRNA was measured by real-time PCR, gastrin peptides were measured by RIA, and gastrin promoter activity was measured by dual-luciferase reporte...

Intermittent Hypoxia Inhibits Na+-H+ Exchange-Mediated Acid Extrusion Via Intracellular Na+ Accumulation in Cardiomyocytes

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Huai-Ren Chang

2018-04-01

Full Text Available Background/Aims: Intermittent hypoxia (IH has been shown to exert preconditioning-like cardioprotective effects. It also has been reported that IH preserves intracellular pH (pHi during ischemia and protects cardiomyocytes against ischemic reperfusion injury. However, the exact mechanism is still unclear. Methods: In this study, we used proton indicator BCECF-AM to analyze the rate of pHi recovery from acidosis in the IH model of rat neonatal cardiomyocytes. Neonatal cardiomyocytes were first treated with repetitive hypoxia-normoxia cycles for 1-4 days. Cells were then acid loaded with NH4Cl, and the rate of pHi recovery from acidosis was measured. Results: We found that the pHi recovery rate from acidosis was much slower in the IH group than in the room air (RA group. When we treated cardiomyocytes with Na+-H+ exchange (NHE inhibitors (Amiloride and HOE642 or Na+-free Tyrode solution during the recovery, there was no difference between RA and IH groups. We also found intracellular Na+ concentration ([Na+]i significantly increased after IH exposure for 4 days. However, the phenomenon could be abolished by pretreatment with ROS inhibitors (SOD and phenanathroline, intracellular calcium chelator or Na+-Ca2+ exchange (NCX inhibitor. Furthermore, the pHi recovery rate from acidosis became faster in the IH group than in the RA group when inhibition of NCX activity. Conclusions: These results suggest that IH would induce the elevation of ROS production. ROS then activates Ca2+-efflux mode of NCX and results in intracellular Na+ accumulation. The rise of [Na+]i further inhibits the activity of NHE-mediated acid extrusion and retards the rate of pHi recovery from acidosis during IH.

Molecular and biochemical responses of hypoxia exposure in Atlantic croaker collected from hypoxic regions in the northern Gulf of Mexico.

Science.gov (United States)

Rahman, Md Saydur; Thomas, Peter

2017-01-01

A major impact of global climate change has been the marked increase worldwide in the incidence of coastal hypoxia (dissolved oxygen, DOhypoxic waters as well as their molecular and physiological responses to environmental hypoxia exposure are largely unknown. A suite of potential hypoxia exposure biomarkers was evaluated in Atlantic croaker collected from hypoxic and normoxic regions in the northern Gulf of Mexico (nGOM), and in croaker after laboratory exposure to hypoxia (DO: 1.7 mg l-1). Expression of hypoxia-inducible factor-α, hif-α; neuronal nitric oxide synthase, nNOS; and insulin-like growth factor binding protein, igfbp mRNAs and protein carbonyl (PC, an oxidative stress indicator) content were elevated several-fold in brain and liver tissues of croaker collected from nGOM hypoxic sites. All of these molecular and biochemical biomarkers were also upregulated ~3-10-fold in croaker brain and liver tissues within 1-2 days of hypoxia exposure in controlled laboratory experiments. These results suggest that hif-αs, nNOS and igfbp-1 transcripts and PC contents are useful biomarkers of environmental hypoxia exposure and some of its physiological effects, making them important components for improved assessments of long-term impacts of environmental hypoxia on fish populations.

Effect of Acute Hypoxia on Post-Exercise Parasympathetic Reactivation in Healthy Men

Science.gov (United States)

Al Haddad, Hani; Mendez-Villanueva, Alberto; Bourdon, Pitre C.; Buchheit, Martin

2012-01-01

In this study we assessed the effect of acute hypoxia on post-exercise parasympathetic reactivation inferred from heart rate (HR) recovery (HRR) and HR variability (HRV) indices. Ten healthy males participated in this study. Following 10 min of seated rest, participants performed 5 min of submaximal running at the speed associated with the first ventilatory threshold (Sub) followed by a 20-s all-out supramaximal sprint (Supra). Both Sub and Supra runs were immediately followed by 15 min of seated passive recovery. The resting and exercise sequence were performed in both normoxia (N) and normobaric hypoxia (H; FiO2 = 15.4%). HRR indices (e.g., heart beats recovered in the first minute after exercise cessation, HRR60s) and vagal-related HRV indices [i.e., natural logarithm of the square root of the mean of the sum of the squared differences between adjacent normal R–R intervals (Ln rMSSD)] were calculated for both conditions. Difference in the changes between N and H for all HR-derived indices were also calculated for both Sub and Supra. HRR60s was greater in N compared with H following Sub only (60 ± 14 vs. 52 ± 19 beats min−1, P = 0.016). Ln rMSSD was greater in N compared with H (post Sub: 3.60 ± 0.45 vs. 3.28 ± 0.44 ms in N and H, respectively, and post Supra: 2.66 ± 0.54 vs. 2.65 ± 0.63 ms, main condition effect P = 0.02). When comparing the difference in the changes, hypoxia decreased HRR60s (−14.3% ± 17.2 vs. 5.2% ± 19.3; following Sub and Supra, respectively; P = 0.03) and Ln rMSSD (−8.6% ± 7.0 vs. 2.0% ± 13.3, following Sub and Supra, respectively; P = 0.08, Cohen’s effect size = 0.62) more following Sub than Supra. While hypoxia may delay parasympathetic reactivation following submaximal exercise, its effect is not apparent following supramaximal exercise. This may suggest that the effect of blood O2 partial pressure on parasympathetic reactivation is limited

Amplexicaule A exerts anti-tumor effects by inducing apoptosis in human breast cancer

Science.gov (United States)

Shu, Guangwen; Wan, Dingrong; He, Feng; Loaec, Morgann; Ding, Yali; Li, Jun; Dovat, Sinisa; Yang, Gaungzhong; Song, Chunhua

2016-01-01

Chemotherapy is the main treatment for patients with breast cancer metastases, but natural alternatives have been receiving attention for their potential as novel anti-tumor reagents. Amplexicaule A (APA) is a flavonoid glucoside isolated from rhizomes of Polygonum amplexicaule D. Don var. sinense Forb (PADF). We found that APA has anti-tumor effects in a breast cancer xenograft mouse model and induces apoptosis in breast cancer cell lines. APA increased levels of cleaved caspase-3,-8,-9 and PARP, which resulted from suppression of MCL-1 and BCL-2 expression in the cells. APA also inactivated the Akt/mTOR pathway in breast cancer cells. Thus, APA exerts a strong anti-tumor effect on breast cancer cells, most likely through induction of apoptosis. Our study is the first to identify this novel anti-tumor compound and provides a new strategy for isolation and separation of single compounds from herbs. PMID:26943775

Mechanisms of c-myc degradation by nickel compounds and hypoxia.

Directory of Open Access Journals (Sweden)

Qin Li

2009-12-01

Full Text Available Nickel (Ni compounds have been found to cause cancer in humans and animal models and to transform cells in culture. At least part of this effect is mediated by stabilization of hypoxia inducible factor (HIF1a and activating its downstream signaling. Recent studies reported that hypoxia signaling might either antagonize or enhance c-myc activity depending on cell context. We investigated the effect of nickel on c-myc levels, and demonstrated that nickel, hypoxia, and other hypoxia mimetics degraded c-myc protein in a number of cancer cells (A549, MCF-7, MDA-453, and BT-474. The degradation of the c-Myc protein was mediated by the 26S proteosome. Interestingly, knockdown of both HIF-1alpha and HIF-2alpha attenuated c-Myc degradation induced by Nickel and hypoxia, suggesting the functional HIF-1alpha and HIF-2alpha was required for c-myc degradation. Further studies revealed two potential pathways mediated nickel and hypoxia induced c-myc degradation. Phosphorylation of c-myc at T58 was significantly increased in cells exposed to nickel or hypoxia, leading to increased ubiquitination through Fbw7 ubiquitin ligase. In addition, nickel and hypoxia exposure decreased USP28, a c-myc de-ubiquitinating enzyme, contributing to a higher steady state level of c-myc ubiquitination and promoting c-myc degradation. Furthermore, the reduction of USP28 protein by hypoxia signaling is due to both protein degradation and transcriptional repression. Nickel and hypoxia exposure significantly increased the levels of dimethylated H3 lysine 9 at the USP28 promoter and repressed its expression. Our study demonstrated that Nickel and hypoxia exposure increased c-myc T58 phosphorylation and decreased USP28 protein levels in cancer cells, which both lead to enhanced c-myc ubiquitination and proteasomal degradation.

Effects and mechanism of oridonin on pulmonary hypertension induced by chronic hypoxia-hypercapnia in rats.

Science.gov (United States)

Wang, Liang-Xing; Sun, Yu; Chen, Chan; Huang, Xiao-Ying; Lin, Quan; Qian, Guo-Qing; Dong, Wei; Chen, Yan-Fan

2009-06-20

Pulmonary arterial hypertension (PAH) is characterized by suppressing apoptosis and enhancing cell proliferation in the vascular wall. Inducing pulmonary artery smooth muscle cells (PASMC) apoptosis had been regarded as a therapeutic approach for PAH. Oridonin can cause apoptosis in many cell lines, while little has been done to evaluate its effect on PASMC. Thirty male Sprague-Dawley rats were randomly assigned to three groups: normal control (NC); hypoxia-hypercapnia (HH); Hypoxia-hypercapnia + oridonin (HHO). Rats were exposed to hypoxia-hypercapnia for four weeks. Cultured human PASMC (HPASMC) were assigned to three groups: normoxia (NO); hypoxia (HY); hypoxia + oridonin (HO). The mean pulmonary artery pressure, mass ratio of right ventricle over left ventricle plus septum (RV/(LV + S)), the ratio of thickness of the pulmonary arteriole wall to vascular external diameter (WT%) and the ratio of the vessel wall area to the total area (WA%) were measured. Morphologic changes of pulmonary arteries were observed under light and electron microscopes. The apoptotic characteristics in vitro and in vivo were detected. The mPAP, RV/(LV + S), WT%, and WA% in the HH group were significantly greater than those in the NC (P HHO groups (P HHO groups; and the expression of Bcl-2 in group HH was greater than that in the NC and HHO groups. HPASMC mitochondrial membrane potentials in group HO was lower than in group HY (P < 0.01), and cyt-C in the cytoplasm, AI, and caspase-9 in the HO group were greater than that in the HY group (P < 0.01), but the expression of Bcl-2 in the HO group was less than that in the HY group (P < 0.05). The results suggest that oridonin can lower pulmonary artery pressure effectively, and inhibit pulmonary artery structural remodeling by inducing smooth cell apoptosis via a mitochondria-dependent pathway.

TGF-β and Hypoxia/Reoxygenation Promote Radioresistance of A549 Lung Cancer Cells through Activation of Nrf2 and EGFR

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Sae-lo-oom Lee

2016-01-01

Full Text Available Although many studies have examined the roles of hypoxia and transforming growth factor- (TGF- β separately in the tumor microenvironment, the effects of simultaneous treatment with hypoxia/reoxygenation and TGF-β on tumor malignancy are unclear. Here, we investigated the effects of redox signaling and oncogenes on cell proliferation and radioresistance in A549 human lung cancer cells in the presence of TGF-β under hypoxia/reoxygenation conditions. Combined treatment with TGF-β and hypoxia activated epidermal growth factor receptor (EGFR and nuclear factor (erythroid-derived 2-like 2 (Nrf2, a redox-sensitive transcription factor. Interestingly, Nrf2 knockdown suppressed the effects of combined treatment on EGFR phosphorylation. In addition, blockade of EGFR signaling also suppressed induction of Nrf2 following combined treatment with hypoxia and TGF-β, indicating that the combined treatment induced positive crosstalk between Nrf2 and EGFR. TGF-β and hypoxia/reoxygenation increased the accumulation of reactive oxygen species (ROS, while treatment with N-acetyl-L-cysteine abolished the activation of Nrf2 and EGFR. Treatment with TGF-β under hypoxic conditions increased the proliferation of A549 cells compared with that after vehicle treatment. Moreover, cells treated with the combined treatment exhibited resistance to ionizing radiation (IR, and knockdown of Nrf2 increased IR-induced cell death under these conditions. Thus, taken together, our findings suggested that TGF-β and hypoxia/reoxygenation promoted tumor progression and radioresistance of A549 cells through ROS-mediated activation of Nrf2 and EGFR.

Hypoxia is increasing in the coastal zone of the Baltic Sea.

Science.gov (United States)

Conley, Daniel J; Carstensen, Jacob; Aigars, Juris; Axe, Philip; Bonsdorff, Erik; Eremina, Tatjana; Haahti, Britt-Marie; Humborg, Christoph; Jonsson, Per; Kotta, Jonne; Lännegren, Christer; Larsson, Ulf; Maximov, Alexey; Medina, Miguel Rodriguez; Lysiak-Pastuszak, Elzbieta; Remeikaité-Nikiené, Nijolé; Walve, Jakob; Wilhelms, Sunhild; Zillén, Lovisa

2011-08-15

Hypoxia is a well-described phenomenon in the offshore waters of the Baltic Sea with both the spatial extent and intensity of hypoxia known to have increased due to anthropogenic eutrophication, however, an unknown amount of hypoxia is present in the coastal zone. Here we report on the widespread unprecedented occurrence of hypoxia across the coastal zone of the Baltic Sea. We have identified 115 sites that have experienced hypoxia during the period 1955-2009 increasing the global total to ca. 500 sites, with the Baltic Sea coastal zone containing over 20% of all known sites worldwide. Most sites experienced episodic hypoxia, which is a precursor to development of seasonal hypoxia. The Baltic Sea coastal zone displays an alarming trend with hypoxia steadily increasing with time since the 1950s effecting nutrient biogeochemical processes, ecosystem services, and coastal habitat.

The effect of progressive hypoxia on school structure and dynamics in Atlantic herring Clupea harengus

DEFF Research Database (Denmark)

Domenici, Paolo; Ferrari, R Silvana; Steffensen, John F

2002-01-01

The effect of progressive hypoxia on the structure and dynamics of herring (Clupea harengus) schools in laboratory conditions was investigated. The length, width and depth of schools of about 20 individuals were measured from video recordings to test the hypothesis that during hypoxia fish schools...... change their shape and volume. School shape (calculated as the ratios of length/depth, width/depth and length/width) did not change significantly during hypoxia. School length, width, depth, area and volume were all significantly increased at 20% oxygen saturation. Volume, area and width were more...... to overtaking or falling back by individual fishes. School integrity and positional dynamics are the outcome of trade-offs among a number of biotic factors, such as food, predator defence, mating behaviour and various physical factors that may impose certain limits. Among these, our results indicate that oxygen...

Intermittent hypoxia increases insulin resistance in genetically obese mice.

Science.gov (United States)

Polotsky, Vsevolod Y; Li, Jianguo; Punjabi, Naresh M; Rubin, Arnon E; Smith, Philip L; Schwartz, Alan R; O'Donnell, Christopher P

2003-10-01

Obstructive sleep apnoea, a syndrome that leads to recurrent intermittent hypoxia, is associated with insulin resistance in obese individuals, but the mechanisms underlying this association remain unknown. We utilized a mouse model to examine the effects of intermittent hypoxia on insulin resistance in lean C57BL/6J mice and leptin-deficient obese (C57BL/6J-Lepob) mice. In lean mice, exposure to intermittent hypoxia for 5 days (short term) resulted in a decrease in fasting blood glucose levels (from 173 +/- 11 mg dl-1 on day 0 to 138 +/- 10 mg dl-1 on day 5, P obese mice, short-term intermittent hypoxia led to a decrease in blood glucose levels accompanied by a 607 +/- 136 % (P intermittent hypoxia was completely abolished by prior leptin infusion. Obese mice exposed to intermittent hypoxia for 12 weeks (long term) developed a time-dependent increase in fasting serum insulin levels (from 3.6 +/- 1.1 ng ml-1 at baseline to 9.8 +/- 1.8 ng ml-1 at week 12, P intermittent hypoxia is dependent on the disruption of leptin pathways.

Does mental exertion alter maximal muscle activation?

Directory of Open Access Journals (Sweden)

Vianney eRozand

2014-09-01

Full Text Available Mental exertion is known to impair endurance performance, but its effects on neuromuscular function remain unclear. The purpose of this study was to test the hypothesis that mental exertion reduces torque and muscle activation during intermittent maximal voluntary contractions of the knee extensors. Ten subjects performed in a randomized order three separate mental exertion conditions lasting 27 minutes each: i high mental exertion (incongruent Stroop task, ii moderate mental exertion (congruent Stroop task, iii low mental exertion (watching a movie. In each condition, mental exertion was combined with ten intermittent maximal voluntary contractions of the knee extensor muscles (one maximal voluntary contraction every 3 minutes. Neuromuscular function was assessed using electrical nerve stimulation. Maximal voluntary torque, maximal muscle activation and other neuromuscular parameters were similar across mental exertion conditions and did not change over time. These findings suggest that mental exertion does not affect neuromuscular function during intermittent maximal voluntary contractions of the knee extensors.

Cytoprotective effects of fisetin against hypoxia-induced cell death in PC12 cells.

Science.gov (United States)

Chen, Pei-Yi; Ho, Yi-Ru; Wu, Ming-Jiuan; Huang, Shun-Ping; Chen, Po-Kong; Tai, Mi-Hsueh; Ho, Chi-Tang; Yen, Jui-Hung

2015-01-01

Fisetin (3,7,3',4'-tetrahydroxyflavone), a flavonol compound of flavonoids, exhibits a broad spectrum of biological activities including anti-oxidant, anti-inflammatory, anti-cancer and neuroprotective effects. The aim of this study is to investigate the cytoprotective effect of fisetin and the underlying molecular mechanism against hypoxia-induced cell death in PC12 cells. The results of this study showed that fisetin significantly restored the cell viability of PC12 cells under both cobalt chloride (CoCl₂)- and low oxygen-induced hypoxic conditions. Treatment with fisetin successfully reduced the CoCl₂-mediated reactive oxygen species (ROS) production, which was accompanied by an increase in the cell viability of PC12 cells. Furthermore, we found that treatment of PC12 cells with fisetin markedly upregulated hypoxia-inducible factor 1α (HIF-1α), its nuclear accumulation and the hypoxia-response element (HRE)-driven transcriptional activation. The fisetin-mediated cytoprotection during CoCl₂ exposure was significantly attenuated through the administration of HIF-1α siRNA. Moreover, we demonstrated that MAPK/ERK kinase 1/2 (MEK1/2), p38 MAPK and phosphatidylinositol 3-kinase (PI3 K) inhibitors significantly blocked the increase in cell survival that was induced by fisetin treatment under hypoxic conditions. Consistently, increased phosphorylation of ERK, p38 and Akt proteins was observed in PC12 cells treated with fisetin. However, the fisetin-induced HRE-driven transcription was not affected by inhibition of these kinase signaling pathways. Current results reveal for the first time that fisetin promotes cell survival and protects against hypoxia-induced cell death through ROS scavenging and the activation of HIF1α-, MAPK/ERK-, p38 MAPK- and PI3 K/Akt-dependent signaling pathways in PC12 cells.

Effects of natural and human-induced hypoxia on coastal benthos

OpenAIRE

Levin, L. A.; Ekau, W.; Gooday, A. J.; Jorissen, F.; Middelburg, J. J.; Naqvi, S. W. A.; Neira, C.; Rabalais, N. N.; Zhang, J.

2009-01-01

Coastal hypoxia (<1.42 ml L⁻¹; 62.5 μM; 2 mg L⁻¹, approx. 30% oxygen saturation) occurs seasonally in many estuaries, fjords, and along open coasts subject to upwelling or excessive riverine nutrient input, and permanently in some isolated seas and marine basins. Underlying causes of hypoxia include enhanced nutrient input from natural causes (upwelling) or anthropogenic origin (eutrophication) and reduction of mixing by...

Dynamic FDG PET for assessing early effects of cerebral hypoxia and resuscitation in new-born pigs

International Nuclear Information System (INIS)

Lange, Charlotte de; Malinen, Eirik; Qu, Hong; Johnsrud, Kjersti; Skretting, Arne; Saugstad, Ola Didrik; Munkeby, Berit H.

2012-01-01

Changes in cerebral glucose metabolism may be an early prognostic indicator of perinatal hypoxic-ischaemic injury. In this study dynamic 18 F-FDG PET was used to evaluate cerebral glucose metabolism in piglets after global perinatal hypoxia and the impact of the resuscitation strategy using room air or hyperoxia. New-born piglets (n = 16) underwent 60 min of global hypoxia followed by 30 min of resuscitation with a fraction of inspired oxygen (FiO 2 ) of 0.21 or 1.0. Dynamic FDG PET, using a microPET system, was performed at baseline and repeated at the end of resuscitation under stabilized haemodynamic conditions. MRI at 3 T was performed for anatomic correlation. Global and regional cerebral metabolic rates of glucose (CMR gl ) were assessed by Patlak analysis for the two time-points and resuscitation groups. Global hypoxia was found to cause an immediate decrease in cerebral glucose metabolism from a baseline level (mean ± SD) of 21.2 ± 7.9 to 12.6 ± 4.7 μmol/min/100 g (p gl but no significant differences in global or regional CMR gl between the resuscitation groups were found. Dynamic FDG PET detected decreased cerebral glucose metabolism early after perinatal hypoxia in piglets. The decrease in CMR gl may indicate early changes of mild cerebral hypoxia-ischaemia. No significant effect of hyperoxic resuscitation on the degree of hypometabolism was found in this early phase after hypoxia. Cerebral FDG PET can provide new insights into mechanisms of perinatal hypoxic-ischaemic injury where early detection plays an important role in instituting therapy. (orig.)

Identifying novel hypoxia-associated markers of chemoresistance in ovarian cancer.

LENUS (Irish Health Repository)

McEvoy, Lynda M

2015-01-01

Ovarian cancer is associated with poor long-term survival due to late diagnosis and development of chemoresistance. Tumour hypoxia is associated with many features of tumour aggressiveness including increased cellular proliferation, inhibition of apoptosis, increased invasion and metastasis, and chemoresistance, mostly mediated through hypoxia-inducible factor (HIF)-1α. While HIF-1α has been associated with platinum resistance in a variety of cancers, including ovarian, relatively little is known about the importance of the duration of hypoxia. Similarly, the gene pathways activated in ovarian cancer which cause chemoresistance as a result of hypoxia are poorly understood. This study aimed to firstly investigate the effect of hypoxia duration on resistance to cisplatin in an ovarian cancer chemoresistance cell line model and to identify genes whose expression was associated with hypoxia-induced chemoresistance.

Hypoxia Is a Critical Parameter for Chondrogenic Differentiation of Human Umbilical Cord Blood Mesenchymal Stem Cells in Type I/III Collagen Sponges

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Tangni Gómez-Leduc

2017-09-01

Full Text Available Umbilical cord blood (UCB is an attractive alternative to bone marrow for isolation of mesenchymal stem cells (MSCs to treat articular cartilage defects. Here, we set out to determine the growth factors (bone morphogenetic protein 2 (BMP-2 and transforming growth factor-β (TGF-β1 and oxygen tension effects during chondrogenesis of human UCB-MSCs for cartilage engineering. Chondrogenic differentiation was induced using 3D cultures in type I/III collagen sponges with chondrogenic factors in normoxia (21% O2 or hypoxia (<5% O2 for 7, 14 and 21 days. Our results show that UCB-MSCs can be committed to chondrogenesis in the presence of BMP-2+TGF-β1. Normoxia induced the highest levels of chondrocyte-specific markers. However, hypoxia exerted more benefit by decreasing collagen X and matrix metalloproteinase-13 (MMP13 expression, two chondrocyte hypertrophy markers. However, a better chondrogenesis was obtained by switching oxygen conditions, with seven days in normoxia followed by 14 days in hypoxia, since these conditions avoid hypertrophy of hUCB-MSC-derived chondrocytes while maintaining the expression of chondrocyte-specific markers observed in normoxia. Our study demonstrates that oxygen tension is a key factor for chondrogenesis and suggests that UBC-MSCs 3D-culture should begin in normoxia to obtain a more efficient chondrocyte differentiation before placing them in hypoxia for chondrocyte phenotype stabilization. UCB-MSCs are therefore a reliable source for cartilage engineering.

Midcervical neuronal discharge patterns during and following hypoxia

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Sandhu, M. S.; Baekey, D. M.; Maling, N. G.; Sanchez, J. C.; Reier, P. J.

2014-01-01

Anatomical evidence indicates that midcervical interneurons can be synaptically coupled with phrenic motoneurons. Accordingly, we hypothesized that interneurons in the C3–C4 spinal cord can display discharge patterns temporally linked with inspiratory phrenic motor output. Anesthetized adult rats were studied before, during, and after a 4-min bout of moderate hypoxia. Neuronal discharge in C3–C4 lamina I–IX was monitored using a multielectrode array while phrenic nerve activity was extracellularly recorded. For the majority of cells, spike-triggered averaging (STA) of ipsilateral inspiratory phrenic nerve activity based on neuronal discharge provided no evidence of discharge synchrony. However, a distinct STA phrenic peak with a 6.83 ± 1.1 ms lag was present for 5% of neurons, a result that indicates a monosynaptic connection with phrenic motoneurons. The majority (93%) of neurons changed discharge rate during hypoxia, and the diverse responses included both increased and decreased firing. Hypoxia did not change the incidence of STA peaks in the phrenic nerve signal. Following hypoxia, 40% of neurons continued to discharge at rates above prehypoxia values (i.e., short-term potentiation, STP), and cells with initially low discharge rates were more likely to show STP (P phrenic motoneuron pool, and these cells can modulate inspiratory phrenic output. In addition, the C3–C4 propriospinal network shows a robust and complex pattern of activation both during and following an acute bout of hypoxia. PMID:25552641

Zeaxanthin Inhibits Hypoxia-Induced VEGF Secretion by RPE Cells through Decreased Protein Levels of Hypoxia-Inducible Factors-1α

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Richard Rosen

2015-01-01

Full Text Available Hypoxia is the most important stimulus leading to upregulation of VEGF in the retina and this is caused by accumulation of hypoxia-inducible factors-1α (HIF-1α protein. The effects of zeaxanthin, a natural phytochemical, on the VEGF and HIF-1α expression in the primary culture of human retinal pigment epithelial (RPE cells were studied. An in vitro RPE cell hypoxia model was established by placing cells under 1% oxygen pressure or by adding cobalt chloride (CoCl2 to the culture medium. RPE cells and conditioned media were collected from cultures treated with and without zeaxanthin under normoxic and hypoxic conditions. VEGF and HIF-1α protein and RNA levels were measured by ELISA kits and RT-PCR, respectively. Hypoxia caused a significant increase of VEGF expression and accumulation of HIF-1α in RPE cells. Zeaxanthin at 50–150 μM significantly inhibited the expression of VEGF and accumulation of HIF-1α protein caused by hypoxia but did not affect expression of VEGF and HIF-1α under normoxic conditions. This is the first report on the effect of zeaxanthin on VEGF and HIF-1α levels in cultured RPE cells and suggests that zeaxanthin may have potential value in the prevention and treatment of various retinal diseases associated with vascular leakage and neovascularization.

Investigating the complexity of respiratory patterns during recovery from severe hypoxia

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Akay, Metin; Sekine, Noriko

2004-03-01

Progressive hypoxemia in anesthetized, peripherally chemodenervated piglets results in initial depression of the phrenic neurogram (PN) culminating in phrenic silence and, eventually, gasping. These changes reverse after the 30 min reoxygenation (recovery) period. To determine if changes in the PN patterns correspond to changes in temporal patterning, we have used the approximate entropy (ApEn) method to examine the effects of maturation on the complexity of breathing patterns in chemodenervated, vagotomized and decerebrated piglets during severe hypoxia and reoxygenation. The phrenic neurogram in piglets was recorded during eupnea (normal breathing), severe hypoxia (gasping) and recovery from severe hypoxia in 31 piglets (2 35 days). Nonlinear dynamical analysis of the phrenic neurogram was performed using the ApEn method. The mean ApEn values for a recording of five consecutive breaths during eupnea, a few phrenic neurogram signals during gasping, the beginning of the recovery period, and five consecutive breaths at every 5 min interval for the 30 min recovery period were calculated. Our data suggest that gasping resulted in reduced duration of the phrenic neurogram, and the gasp-like patterns exist at the beginning of the recovery. But, the durations of phrenic neurograms during recovery were increased after 10 min postreoxygenation, but were restored 30 min post recovery. The ApEn (complexity) values of the phrenic neurogram during eupnea were higher than those of gasping and the early (the onset of) recovery from severe hypoxia (p < 0.01), but were not statistically different than 5 min post recovery regardless of the maturation stages. These results suggest that hypoxia results in a reversible reconfiguration of the central respiratory pattern generator.

Fetal blood vessel count increases in compensation of hypoxia in premature placentas

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K. Kartini

2015-04-01

Full Text Available Background Prematurity refers to live births before 37 weeks of gestation, wherein the baby is born before the body and its organ systems achieve perfect maturity, and this disorder is still a global problem. The high incidence of prematurity is a problem in developing and also in developed countries. Certain conditions accompanying pregnancies like preeclampsia, infection, and placental insufficiency, may trigger uterine hypoxia, causing premature birth. The placental condition is related to the intra-uterine fetal condition. In prolonged placental hypoxia, there occurs a compensatory mechanism, i.e. an increase in placental angiogenesis. This study aimed to evaluate the effect of hypoxia on fetal blood vessel count as compensatory mechanism for tissue hypoxia. Methods An observational-analytical cross-sectional design using paraffin blocks of conserved premature placentas, comprising 31 samples of hypoxic premature placentas and 28 samples of non-hypoxic premature placentas, selected using non-random consecutive sampling. The samples were made into slides and stained with hematoxylin-eosin for assessment of histological structure, including fetal blood vessel count and integrity, villus conditions, syncytiotrophoblastic nuclear changes, and syncytiotrophoblastic nuclear aggregation. Mann-Whitney test was used to compare the difference of blood vessel count between groups. Results Assessment of histological structure showed a significant increase in fetal blood vessel count in the hypoxic group [8.00 (5-15] as compared with the non-hypoxic group [7.50 (3-15]. Conclusion The hypoxia in premature placentas caused an increase in the number of fetal blood vessels as a form of compensation for disturbed oxygen homeostasis.

Fetal blood vessel count increases in compensation of hypoxia in premature placentas

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K Kartini

2016-02-01

Full Text Available BACKGROUND Prematurity refers to live births before 37 weeks of gestation, wherein the baby is born before the body and its organ systems achieve perfect maturity, and this disorder is still a global problem. The high incidence of prematurity is a problem in developing and also in developed countries. Certain conditions accompanying pregnancies like preeclampsia, infection, and placental insufficiency, may trigger uterine hypoxia, causing premature birth. The placental condition is related to the intra-uterine fetal condition. In prolonged placental hypoxia, there occurs a compensatory mechanism, i.e. an increase in placental angiogenesis. This study aimed to evaluate the effect of hypoxia on fetal blood vessel count as compensatory mechanism for tissue hypoxia. METHODS An observational-analytical cross-sectional design using paraffin blocks of conserved premature placentas, comprising 31 samples of hypoxic premature placentas and 28 samples of non-hypoxic premature placentas, selected using non-random consecutive sampling. The samples were made into slides and stained with hematoxylin-eosin for assessment of histological structure, including fetal blood vessel count and integrity, villus conditions, syncytiotrophoblastic nuclear changes, and syncytiotrophoblastic nuclear aggregation. Mann-Whitney test was used to compare the difference of blood vessel count between groups. RESULTS Assessment of histological structure showed a significant increase in fetal blood vessel count in the hypoxic group [8.00 (5-15] as compared with the non-hypoxic group [7.50 (3-15]. CONCLUSION The hypoxia in premature placentas caused an increase in the number of fetal blood vessels as a form of compensation for disturbed oxygen homeostasis.

Notch-1 mediates hypoxia-induced angiogenesis in rheumatoid arthritis.

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Gao, Wei; Sweeney, Catherine; Connolly, Mary; Kennedy, Aisling; Ng, Chin Teck; McCormick, Jennifer; Veale, Douglas J; Fearon, Ursula

2012-07-01

To examine the effect of hypoxia on Notch-1 signaling pathway components and angiogenesis in inflammatory arthritis. The expression and regulation of Notch-1, its ligand delta-like protein 4 (DLL-4) and downstream signaling components (hairy-related transcription factor 1 [HRT-1], HRT-2), and hypoxia-inducible factor 1α (HIF-1α) under normoxic and hypoxic conditions (1-3%) were assessed in synovial tissue specimens from patients with inflammatory arthritis and controls and in human dermal microvascular endothelial cells (HDMECs) by immunohistology, dual immunofluorescence staining (Notch-1/factor VIII), Western blotting, and real-time polymerase chain reaction. In vivo synovial tissue oxygen levels (tissue PO2) were measured under direct visualization at arthroscopy. HDMEC activation under hypoxic conditions in the presence of Notch-1 small interfering RNA (siRNA), the γ-secretase inhibitor DAPT, or dimethyloxalylglycine (DMOG) was assessed by Matrigel tube formation assay, migration assay, invasion assay, and matrix metalloproteinase 2 (MMP-2)/MMP-9 zymography. Expression of Notch-1, its ligand DLL-4, and HRT-1 was demonstrated in synovial tissue, with the strongest expression localized to perivascular/vascular regions. Localization of Notch-1 to synovial endothelium was confirmed by dual immunofluorescence staining. Notch-1 intracellular domain (NICD) expression was significantly higher in synovial tissue from patients with tissue PO2 of PO2 of >20 mm Hg (>3% O2). Exposure of HDMECs to 3% hypoxia induced HIF-1α and NICD protein expression and DLL-4, HRT-1, and HRT-2 messenger RNA expression. DMOG directly induced NICD expression, while Notch-1 siRNA inhibited hypoxia-induced HIF-1α expression, suggesting that Notch-1/HIF-1α signaling is bidirectional. Finally, 3% hypoxia-induced angiogenesis, endothelial cell migration, endothelial cell invasion, and proMMP-2 and proMMP-9 activities were inhibited by Notch-1 siRNA and/or the γ-secretase inhibitor DAPT. Our

Acute hypoxia diminishes the relationship between blood pressure and subarachnoid space width oscillations at the human cardiac frequency.

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Magdalena Wszedybyl-Winklewska

Full Text Available Acute hypoxia exerts strong effects on the cardiovascular system. Heart-generated pulsatile cerebrospinal fluid motion is recognised as a key factor ensuring brain homeostasis. We aimed to assess changes in heart-generated coupling between blood pressure (BP and subarachnoid space width (SAS oscillations during hypoxic exposure.Twenty participants were subjected to a controlled decrease in oxygen saturation (SaO2 = 80% for five minutes. BP and heart rate (HR were measured using continuous finger-pulse photoplethysmography, oxyhaemoglobin saturation with an ear-clip sensor, end-tidal CO2 with a gas analyser, and cerebral blood flow velocity (CBFV, pulsatility and resistive indices with Doppler ultrasound. Changes in SAS were recorded with a recently-developed method called near-infrared transillumination/backscattering sounding. Wavelet transform analysis was used to assess the relationship between BP and SAS oscillations.Gradual increases in systolic, diastolic BP and HR were observed immediately after the initiation of hypoxic challenge (at fifth minute +20.1%, +10.2%, +16.5% vs. baseline, respectively; all P<0.01, whereas SAS remained intact (P = NS. Concurrently, the CBFV was stable throughout the procedure, with the only increase observed in the last two minutes of deoxygenation (at the fifth minute +6.8% vs. baseline, P<0.05. The cardiac contribution to the relationship between BP and SAS oscillations diminished immediately after exposure to hypoxia (at the fifth minute, right hemisphere -27.7% and left hemisphere -26.3% vs. baseline; both P<0.05. Wavelet phase coherence did not change throughout the experiment (P = NS.Cerebral haemodynamics seem to be relatively stable during short exposure to normobaric hypoxia. Hypoxia attenuates heart-generated BP SAS coupling.

Nuclear Orphan Receptor TLX Induces Oct-3/4 for the Survival and Maintenance of Adult Hippocampal Progenitors upon Hypoxia*

OpenAIRE

Chavali, Pavithra Lakshminarasimhan; Saini, Ravi Kanth Rao; Matsumoto, Yoshiki; Ågren, Hans; Funa, Keiko

2010-01-01

Hypoxia promotes neural stem cell proliferation, the mechanism of which is poorly understood. Here, we have identified the nuclear orphan receptor TLX as a mediator for proliferation and pluripotency of neural progenitors upon hypoxia. We found an enhanced early protein expression of TLX under hypoxia potentiating sustained proliferation of neural progenitors. Moreover, TLX induction upon hypoxia in differentiating conditions leads to proliferation and a stem cell-like phenotype, along with c...

Human Primary Trophoblast Cell Culture Model to Study the Protective Effects of Melatonin Against Hypoxia/reoxygenation-induced Disruption.

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Sagrillo-Fagundes, Lucas; Clabault, Hélène; Laurent, Laetitia; Hudon-Thibeault, Andrée-Anne; Salustiano, Eugênia Maria Assunção; Fortier, Marlène; Bienvenue-Pariseault, Josianne; Wong Yen, Philippe; Sanderson, J Thomas; Vaillancourt, Cathy

2016-07-30

This protocol describes how villous cytotrophoblast cells are isolated from placentas at term by successive enzymatic digestions, followed by density centrifugation, media gradient isolation and immunomagnetic purification. As observed in vivo, mononucleated villous cytotrophoblast cells in primary culture differentiate into multinucleated syncytiotrophoblast cells after 72 hr. Compared to normoxia (8% O2), villous cytotrophoblast cells that undergo hypoxia/reoxygenation (0.5% / 8% O2) undergo increased oxidative stress and intrinsic apoptosis, similar to that observed in vivo in pregnancy complications such as preeclampsia, preterm birth, and intrauterine growth restriction. In this context, primary villous trophoblasts cultured under hypoxia/reoxygenation conditions represent a unique experimental system to better understand the mechanisms and signalling pathways that are altered in human placenta and facilitate the search for effective drugs that protect against certain pregnancy disorders. Human villous trophoblasts produce melatonin and express its synthesizing enzymes and receptors. Melatonin has been suggested as a treatment for preeclampsia and intrauterine growth restriction because of its protective antioxidant effects. In the primary villous cytotrophoblast cell model described in this paper, melatonin has no effect on trophoblast cells in normoxic state but restores the redox balance of syncytiotrophoblast cells disrupted by hypoxia/reoxygenation. Thus, human villous trophoblast cells in primary culture are an excellent approach to study the mechanisms behind the protective effects of melatonin on placental function during hypoxia/reoxygenation.

Developmental control of hypoxia during bud burst in grapevine.

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Meitha, Karlia; Agudelo-Romero, Patricia; Signorelli, Santiago; Gibbs, Daniel J; Considine, John A; Foyer, Christine H; Considine, Michael J

2018-05-01

Dormant or quiescent buds of woody perennials are often dense and in the case of grapevine (Vitis vinifera L.) have a low tissue oxygen status. The precise timing of the decision to resume growth is difficult to predict, but once committed, the increase in tissue oxygen status is rapid and developmentally regulated. Here, we show that more than a third of the grapevine homologues of widely conserved hypoxia-responsive genes and nearly a fifth of all grapevine genes possessing a plant hypoxia-responsive promoter element were differentially regulated during bud burst, in apparent harmony with resumption of meristem identity and cell-cycle gene regulation. We then investigated the molecular and biochemical properties of the grapevine ERF-VII homologues, which in other species are oxygen labile and function in transcriptional regulation of hypoxia-responsive genes. Each of the 3 VvERF-VIIs were substrates for oxygen-dependent proteolysis in vitro, as a function of the N-terminal cysteine. Collectively, these data support an important developmental function of oxygen-dependent signalling in determining the timing and effective coordination bud burst in grapevine. In addition, novel regulators, including GASA-, TCP-, MYB3R-, PLT-, and WUS-like transcription factors, were identified as hallmarks of the orderly and functional resumption of growth following quiescence in buds. © 2018 John Wiley & Sons Ltd.

The effects of the painkiller diclofenac and hypoxia on gene transcription and antioxidant system in the gills of three-spined stickleback.

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Lubiana, Pedro; Prokkola, Jenni M; Nikinmaa, Mikko; Burmester, Thorsten; Kanerva, Mirella; Götting, Miriam

2016-01-01

Aquatic organisms face multiple stressors in natural ecosystems. More and more often painkillers are detected in surface waters since their prescription has increased worldwide within the last years. Here we examined the effects of the non-steroidal anti-inflammatory drug (NSAID) diclofenac and hypoxia on three-spined sticklebacks (Gasterosteus aculeatus). We exposed sticklebacks to an environmentally relevant concentration of diclofenac (1μg/L) for 14days, to 24h of hypoxia (2.0mg O2/L), and a combination of both. Hypoxia and diclofenac both can be associated with oxidative stress in fish, but it is unclear whether they would act synergistically. Expression analysis of genes related to antioxidant response, hypoxia response, and chemical metabolism in gills showed that diclofenac alone had little effect, while the combination of hypoxia and diclofenac affected transcript levels most, indicating synergistic effects of these stressors. Of the antioxidant enzymes, only superoxide dismutase activity remained unchanged by treatments, while glutathione peroxidase (GPx) was the most affected antioxidant response on both the transcript and activity levels. Our results suggest that diclofenac may lead to suppressed catalase (CAT) activity but increased GPx activity, probably as compensatory mechanism to remove increasing H2O2 in the gills, and that this response is not affected by hypoxia. The activities of lactate dehydrogenase, CAT, and GPx also showed temporal variability during treatments, which can be attributable to tissue-specific circadian rhythms. Our study shows how responses to NSAIDs and hypoxia can interact in fish, suggesting that getting more insight into temporal variation and about the different levels of regulation of environmental responses is necessary in future studies. Copyright © 2016. Published by Elsevier Inc.

Preventive effect of piracetam and vinpocetine on hypoxia-reoxygenation induced injury in primary hippocampal culture.

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Solanki, P; Prasad, D; Muthuraju, S; Sharma, A K; Singh, S B; Ilavzhagan, G

2011-04-01

The present study investigates the potential of Piracetam and Vinpocetine (nootropic drugs, known to possess neuroprotective properties) in preventing hypoxia-reoxygenation induced oxidative stress in primary hippocampal cell culture. The hippocampal culture was exposed to hypoxia (95% N(2), 5% CO(2)) for 3h and followed by 1h of reoxygenation (21% O(2) and 5% CO(2)) at 37 °C. The primary hippocampal cultures were supplemented with the optimum dose of Piracetam and Vinpocetine, independently, and the cultures were divided into six groups, viz. Control/Normoxia, Hypoxia, Hypoxia+Piracetam, Hypoxia+Vinpocetine, Normoxia + Piracetam and Normoxia+Vinpocetine. The cell-viability assays and biochemical oxidative stress parameters were evaluated for each of the six groups. Administration of 1mM Piracetam or 500 nM Vinpocetine significantly prevents the culture from hypoxia-reoxygenation injury when determined by Neutral Red assay, LDH release and Acetylcholine esterase activity. Results showed that Piracetam and Vinpocetine supplementation significantly prevented the fall of mitochondrial membrane potential, rise in ROS generation and reduction in antioxidant levels associated with the hypoxia-reoxygenation injury. In conclusion, the present study establishes that both Piracetam and Vinpocetine give neuroprotection against hypoxia-reoxygenation injury in primary hippocampal cell culture. Copyright © 2010 Elsevier Ltd. All rights reserved.

[Vasoprotective effect of adaptation to hypoxia in myocardial ischemia and reperfusion injury].

Science.gov (United States)

Manukhina, E B; Terekhina, O L; Belkina, L M; Abramochkin, D V; Budanova, O P; Mashina, S Yu; Smirin, B V; Yakunina, E B; Downey, H F

2013-01-01

Adaptation to hypoxia is known to be cardioprotective in ischemic and reperfusion (IR) injury of the myocardium. This study was focused on investigating a possibility for prevention of endothelial dysfunction in IR injury of the rat heart using adaptation to intermittent hypoxia, which was performed in a cyclic mode (5-10 min of hypoxia interspersed with 4 min of normoxia, 5-8 cycles daily) for 21 days. Endothelial function of coronary blood vessels was evaluated after the in vitro IR of isolated heart (15 min of ischemia and 10 min of reperfusion) by the increment of coronary flow rate in response to acetylcholine. Endothelium-dependent relaxation of isolated rat aorta was evaluated after the IR myocardial injury in situ (30 min of ischemia and 60 min of reperfusion) by a relaxation response of noradrenaline-precontracted vessel rings to acetylcholine. The following major results were obtained in this study: 1) IR myocardial injury induced endothelial dysfunction of coronary blood vessels and the aorta, a non-coronary blood vessel, remote from the IR injury area; and 2) adaptation to hypoxia prevented the endothelial dysfunction of both coronary and non-coronary blood vessels associated with the IR injury. Therefore, adaptation to hypoxia is not only cardioprotective but also vasoprotective in myocardial IR injury.

Pimonidazole: a novel hypoxia marker for complementary study of tumor hypoxia and tumor biology

International Nuclear Information System (INIS)

Varia, Mahesh A.; Kennedy, Andrew S.; Calkins-Adams, Dennise P.; Rinker, Lillian; Novotny, Debra; Fowler, Wesley C.; Raleigh, James A.

1997-01-01

Purpose/Objectives: Tumor hypoxia appears to be associated with treatment resistance and with gene expression that may lead to hypoxia-mediated selection of tumor cells as a source for cell growth and metastases. The objective of this study was to develop complementary techniques of hypoxia detection with molecular markers of cell proliferation and metastases in order to investigate the role of tumor hypoxia in tumor biology. Materials and Methods: Pimonidazole is a 2-nitroimidazole which is reductively-activated and becomes covalently bound to thiol-containing proteins only in hypoxic cells. These adducts can be detected using immunohistochemistry, enzyme linked immunosorbent assay or flow cytometry as a measure of hypoxia in tumors. Quantitative immunohistochemical analysis has been completed for five patients with squamous cell carcinoma of the cervix who were given pimonidazole hydrochloride (0.5 g/m 2 intravenously) followed by cervical biopsies 24 hours later. Informed consent was obtained according to a protocol approved by the Institutional Review Board. A minimum of 3 random biopsies were obtained from the tumors and at least four sections examined from each biopsy site. Formalin fixed, paraffin embedded tissue sections were immunostained for pimonidazole binding using a mouse monoclonal antibody. Commercially available monoclonal antibodies were used to detect cell proliferation markers MIB-1 (Ki-67) and to detect vascular endothelial growth factor (VEGF) in tumor cells in contiguous sections. The extent of immunostaining was expressed as the percent of immunostained to total tumor cells as determined by Chalkley point counting. Results: No clinical toxicities were associated with pimonidazole infusion. Immunostaining with pimonidazole antibody was observed in all patients indicating the presence of tumor hypoxia. Qualitatively there is little or no overlap between the areas of hypoxia and proliferation. Quantitative data tabulated below show the

Cognitive responses to hypobaric hypoxia: implications for aviation training

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Neuhaus C

2014-11-01

Full Text Available Christopher Neuhaus,1,2 Jochen Hinkelbein2,31Department of Anesthesiology, Heidelberg University Hospital, Ruprecht Karls University of Heidelberg, Heidelberg, 2Emergency Medicine and Air Rescue Working Group, German Society of Aviation and Space Medicine (DGLRM, Munich, 3Department of Anesthesiology and Intensive Care Medicine, University Hospital of Cologne, Cologne, GermanyAbstract: The aim of this narrative review is to provide an overview on cognitive responses to hypobaric hypoxia and to show relevant implications for aviation training. A principal element of hypoxia-awareness training is the intentional evocation of hypoxia symptoms during specific training sessions within a safe and controlled environment. Repetitive training should enable pilots to learn and recognize their personal hypoxia symptoms. A time span of 3–6 years is generally considered suitable to refresh knowledge of the more subtle and early symptoms especially. Currently, there are two different technical approaches available to induce hypoxia during training: hypobaric chamber training and reduced-oxygen breathing devices. Hypoxia training for aircrew is extremely important and effective, and the hypoxia symptoms should be emphasized clearly to aircrews. The use of tight-fitting masks, leak checks, and equipment checks should be taught to all aircrew and reinforced regularly. It is noteworthy that there are major differences in the required quality and quantity of hypoxia training for both military and civilian pilots.Keywords: cognitive response, aviation training, pilot, hypoxia, oxygen, loss of consciousness

Melatonin modulates the fetal cardiovascular defense response to acute hypoxia.

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Thakor, Avnesh S; Allison, Beth J; Niu, Youguo; Botting, Kimberley J; Serón-Ferré, Maria; Herrera, Emilio A; Giussani, Dino A

2015-08-01

Experimental studies in animal models supporting protective effects on the fetus of melatonin in adverse pregnancy have prompted clinical trials in human pregnancy complicated by fetal growth restriction. However, the effects of melatonin on the fetal defense to acute hypoxia, such as that which may occur during labor, remain unknown. This translational study tested the hypothesis, in vivo, that melatonin modulates the fetal cardiometabolic defense responses to acute hypoxia in chronically instrumented late gestation fetal sheep via alterations in fetal nitric oxide (NO) bioavailability. Under anesthesia, 6 fetal sheep at 0.85 gestation were instrumented with vascular catheters and a Transonic flow probe around a femoral artery. Five days later, fetuses were exposed to acute hypoxia with or without melatonin treatment. Fetal blood was taken to determine blood gas and metabolic status and plasma catecholamine concentrations. Hypoxia during melatonin treatment was repeated during in vivo NO blockade with the NO clamp. This technique permits blockade of de novo synthesis of NO while compensating for the tonic production of the gas, thereby maintaining basal cardiovascular function. Melatonin suppressed the redistribution of blood flow away from peripheral circulations and the glycemic and plasma catecholamine responses to acute hypoxia. These are important components of the fetal brain sparing response to acute hypoxia. The effects of melatonin involved NO-dependent mechanisms as the responses were reverted by fetal treatment with the NO clamp. Melatonin modulates the in vivo fetal cardiometabolic responses to acute hypoxia by increasing NO bioavailability. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Vitamin E supplementation inhibits muscle damage and inflammation after moderate exercise in hypoxia.

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Santos, S A; Silva, E T; Caris, A V; Lira, F S; Tufik, S; Dos Santos, R V T

2016-08-01

Exercise under hypoxic conditions represents an additional stress in relation to exercise in normoxia. Hypoxia induces oxidative stress and inflammation as mediated through tumour necrosis factor (TNF)-α release that might be exacerbated through exercise. In addition, vitamin E supplementation might attenuate oxidative stress and inflammation resulting from hypoxia during exercise. The present study aimed to evaluate the effects of vitamin E supplementation (250 mg) on inflammatory parameters and cellular damage after exercise under hypoxia simulating an altitude of 4200 m. Nine volunteers performed three sessions of 60 min of exercise (70% maximal oxygen uptake) interspersed for 1 week under normoxia, hypoxia and hypoxia after vitamin E supplementation 1 h before exercise. Blood was collected before, immediately after and at 1 h after exercise to measure inflammatory parameters and cell damage. Percentage oxygen saturation of haemoglobin decreased after exercise and recovered 1 h later in the hypoxia + vitamin condition (P exercise (P exercise in hypoxia increased interleukin (IL)-6, TNF-α, IL-1ra and IL-10 immediately after exercise (P exercise in hypoxia without supplementation (P exercise reduces cell damage markers after exercise in hypoxia and changes the concentration of cytokines, suggesting a possible protective effect against inflammation induced by hypoxia during exercise. © 2016 The British Dietetic Association Ltd.

Hypoxia-independent upregulation of placental hypoxia inducible factor-1α gene expression contributes to the pathogenesis of preeclampsia.

Science.gov (United States)

Iriyama, Takayuki; Wang, Wei; Parchim, Nicholas F; Song, Anren; Blackwell, Sean C; Sibai, Baha M; Kellems, Rodney E; Xia, Yang

2015-06-01

Accumulation of hypoxia inducible factor-1α (HIF-1α) is commonly an acute and beneficial response to hypoxia, whereas chronically elevated HIF-1α is associated with multiple disease conditions, including preeclampsia, a serious hypertensive disease of pregnancy. However, the molecular basis underlying the persistent elevation of placental HIF-1α in preeclampsia and its role in the pathogenesis of preeclampsia are poorly understood. Here we report that Hif-1α mRNA and HIF-1α protein were elevated in the placentas of pregnant mice infused with angiotensin II type I receptor agonistic autoantibody, a pathogenic factor in preeclampsia. Knockdown of placental Hif-1α mRNA by specific siRNA significantly attenuated hallmark features of preeclampsia induced by angiotensin II type I receptor agonistic autoantibody in pregnant mice, including hypertension, proteinuria, kidney damage, impaired placental vasculature, and elevated maternal circulating soluble fms-like tyrosine kinase-1 levels. Next, we discovered that Hif-1α mRNA levels and HIF-1α protein levels were induced in an independent preeclampsia model with infusion of the inflammatory cytokine tumor necrosis factor superfamily member 14 (LIGHT). SiRNA knockdown experiments also demonstrated that elevated HIF-1α contributed to LIGHT-induced preeclampsia features. Translational studies with human placentas showed that angiotensin II type I receptor agonistic autoantibody or LIGHT is capable of inducing HIF-1α in a hypoxia-independent manner. Moreover, increased HIF-1α was found to be responsible for angiotensin II type I receptor agonistic autoantibody or LIGHT-induced elevation of Flt-1 gene expression and production of soluble fms-like tyrosine kinase-1 in human villous explants. Overall, we demonstrated that hypoxia-independent stimulation of HIF-1α gene expression in the placenta is a common pathogenic mechanism promoting disease progression. Our findings reveal new insight to preeclampsia and highlight

Disturbance of recruitment success of mantis shrimp in Tokyo Bay associated with effects of hypoxia on the early life history.

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Kodama, Keita; Tajima, Yoshihiro; Shimizu, Takamichi; Ohata, Satoshi; Shiraishi, Hiroaki; Horiguchi, Toshihiro

2014-08-30

We investigated effects of severe hypoxia (dissolved oxygen shrimp Oratosquilla oratoria in Tokyo Bay. Ten-year field surveys were conducted to examine quantitative relationships in annual mean densities of larvae and juveniles, and spatial distribution of juveniles and severe hypoxia. There was no significant correlation between annual mean densities of larvae and juveniles, suggesting that mortality during larval or juvenile stages varies among years, which might have regulated abundance of young-of-the-year juveniles. Juvenile density was low in the severely hypoxic area, implying that hypoxia could affect survivals and spatial distribution of juveniles. Meanwhile, there are yearly fluctuations in juvenile density in normoxic areas of both northern and southern part of the bay. This evidence suggests that abundance of post-settled juveniles might have been determined by not only effects of hypoxia, but also other factors influencing mortality during the early life stages. Copyright © 2014 Elsevier Ltd. All rights reserved.

Snail/beta-catenin signaling protects breast cancer cells from hypoxia attack

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Scherbakov, Alexander M., E-mail: alex.scherbakov@gmail.com [Laboratory of Clinical Biochemistry, Institute of Clinical Oncology, N.N. Blokhin Cancer Research Centre, Kashirskoye sh. 24, Moscow 115478 (Russian Federation); Stefanova, Lidia B.; Sorokin, Danila V.; Semina, Svetlana E. [Laboratory of Molecular Endocrinology, Institute of Carcinogenesis, N.N. Blokhin Cancer Research Centre, Kashirskoye sh. 24, Moscow 115478 (Russian Federation); Berstein, Lev M. [Laboratory of Oncoendocrinology, N.N. Petrov Research Institute of Oncology, St. Petersburg 197758 (Russian Federation); Krasil’nikov, Mikhail A. [Laboratory of Molecular Endocrinology, Institute of Carcinogenesis, N.N. Blokhin Cancer Research Centre, Kashirskoye sh. 24, Moscow 115478 (Russian Federation)

2013-12-10

The tolerance of cancer cells to hypoxia depends on the combination of different factors – from increase of glycolysis (Warburg Effect) to activation of intracellular growth/apoptotic pathways. Less is known about the influence of epithelial–mesenchymal transition (EMT) and EMT-associated pathways on the cell sensitivity to hypoxia. The aim of this study was to explore the role of Snail signaling, one of the key EMT pathways, in the mediating of hypoxia response and regulation of cell sensitivity to hypoxia, using as a model in vitro cultured breast cancer cells. Earlier we have shown that estrogen-independent HBL-100 breast cancer cells differ from estrogen-dependent MCF-7 cells with increased expression of Snail1, and demonstrated Snail1 involvement into formation of hormone-resistant phenotype. Because Snail1 belongs to hypoxia-activated proteins, here we studied the influence of Snail1 signaling on the cell tolerance to hypoxia. We found that Snail1-enriched HBL-100 cells were less sensitive to hypoxia-induced growth suppression if compared with MCF-7 line (31% MCF-7 vs. 71% HBL-100 cell viability after 1% O{sub 2} atmosphere for 3 days). Snail1 knock-down enhanced the hypoxia-induced inhibition of cell proliferation giving the direct evidence of Snail1 involvement into cell protection from hypoxia attack. The protective effect of Snail1 was shown to be mediated, at least in a part, via beta-catenin which positively regulated expression of HIF-1-dependent genes. Finally, we found that cell tolerance to hypoxia was accompanied with the failure in the phosphorylation of AMPK – the key energy sensor, and demonstrated an inverse relationship between AMPK and Snail/beta-catenin signaling. Totally, our data show that Snail1 and beta-catenin, besides association with loss of hormone dependence, protect cancer cells from hypoxia and may serve as an important target in the treatment of breast cancer. Moreover, we suggest that the level of these proteins as well

Elevation of hypoxia resistance with the use of gutimine

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Vinogradov, V.M.; Pastushenkov, L.V.; Sumina, E.N.

Experimental data demonstrating the protection from the adverse effects of hypoxia offered by the antioxidant gutimine and its analogs are presented. The experiments included preliminary studies of hypoxia resistance and recovery under simulated altitude, studies of circulatory hypoxia in the brain and in intrauterine fetuses, studies of myocardial ischemia during acute and chronic experiments and studies where cardiac, kidney and limb circulation is cut off. The compound was also found to be effective in cases of hemorrhagic hypotension, complex hypoxia in peritonitis, meningococcal meningitis, and the weakening of uterine muscle contractility during prolonged deliveries, and in cranial-cerebral trauma. Mechanisms of the antihypoxic action of gutimine and its analogs have been found to include the reduction of oxygen utilization, the activation of aerobic and anaerobic metabolism, the acceleration of lactate utilization, the inhibition of lipolysis in fat tissue, and stabilization of cell membranes. Clinical observations also support the experimental data.

Effect of acute hypobaric hypoxia on the endothelial glycocalyx and digital reactive hyperemia in humans

DEFF Research Database (Denmark)

Johansson, Pär I; Bergström, Anita; Aachmann-Andersen, Niels Jacob

2014-01-01

INTRODUCTION: Hypoxia is associated with increased capillary permeability. This study tested whether acute hypobaric hypoxia involves degradation of the endothelial glycocalyx. METHODS: We exposed 12 subjects to acute hypobaric hypoxia (equivalent to 4500 m for 2-4 h) and measured venous blood...

Musical agency reduces perceived exertion during strenuous physical performance.

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Fritz, Thomas Hans; Hardikar, Samyogita; Demoucron, Matthias; Niessen, Margot; Demey, Michiel; Giot, Olivier; Li, Yongming; Haynes, John-Dylan; Villringer, Arno; Leman, Marc

2013-10-29

Music is known to be capable of reducing perceived exertion during strenuous physical activity. The current interpretation of this modulating effect of music is that music may be perceived as a diversion from unpleasant proprioceptive sensations that go along with exhaustion. Here we investigated the effects of music on perceived exertion during a physically strenuous task, varying musical agency, a task that relies on the experience of body proprioception, rather than simply diverting from it. For this we measured psychologically indicated exertion during physical workout with and without musical agency while simultaneously acquiring metabolic values with spirometry. Results showed that musical agency significantly decreased perceived exertion during workout, indicating that musical agency may actually facilitate physically strenuous activities. This indicates that the positive effect of music on perceived exertion cannot always be explained by an effect of diversion from proprioceptive feedback. Furthermore, this finding suggests that the down-modulating effect of musical agency on perceived exertion may be a previously unacknowledged driving force for the development of music in humans: making music makes strenuous physical activities less exhausting.

Protective effects of myricetin on acute hypoxia-induced exercise intolerance and mitochondrial impairments in rats.

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Dan Zou

Full Text Available Exercise tolerance is impaired in hypoxia. The aim of this study was to evaluate the effects of myricetin, a dietary flavonoid compound widely found in fruits and vegetables, on acute hypoxia-induced exercise intolerance in vivo and in vitro.Male rats were administered myricetin or vehicle for 7 days and subsequently spent 24 hours at a barometric pressure equivalent to 5000 m. Exercise capacity was then assessed through the run-to-fatigue procedure, and mitochondrial morphology in skeletal muscle cells was observed by transmission electron microscopy (TEM. The enzymatic activities of electron transfer complexes were analyzed using an enzyme-linked immuno-sorbent assay (ELISA. mtDNA was quantified by real-time-PCR. Mitochondrial membrane potential was measured by JC-1 staining. Protein expression was detected through western blotting, immunohistochemistry, and immunofluorescence.Myricetin supplementation significantly prevented the decline of run-to-fatigue time of rats in hypoxia, and attenuated acute hypoxia-induced mitochondrial impairment in skeletal muscle cells in vivo and in vitro by maintaining mitochondrial structure, mtDNA content, mitochondrial membrane potential, and activities of the respiratory chain complexes. Further studies showed that myricetin maintained mitochondrial biogenesis in skeletal muscle cells under hypoxic conditions by up-regulating the expressions of mitochondrial biogenesis-related regulators, in addition, AMP-activated protein kinase(AMPK plays a crucial role in this process.Myricetin may have important applications for improving physical performance under hypoxic environment, which may be attributed to the protective effect against mitochondrial impairment by maintaining mitochondrial biogenesis.

Augmentation of aerobic respiration and mitochondrial biogenesis in skeletal muscle by hypoxia preconditioning with cobalt chloride

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Saxena, Saurabh [Experimental Biology Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi, 110054 (India); Shukla, Dhananjay [Department of Biotechnology, Gitam University, Gandhi Nagar, Rushikonda, Visakhapatnam-530 045 Andhra Pradesh (India); Bansal, Anju, E-mail: anjubansaldipas@gmail.com [Experimental Biology Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi, 110054 (India)

2012-11-01

High altitude/hypoxia training is known to improve physical performance in athletes. Hypoxia induces hypoxia inducible factor-1 (HIF-1) and its downstream genes that facilitate hypoxia adaptation in muscle to increase physical performance. Cobalt chloride (CoCl{sub 2}), a hypoxia mimetic, stabilizes HIF-1, which otherwise is degraded in normoxic conditions. We studied the effects of hypoxia preconditioning by CoCl{sub 2} supplementation on physical performance, glucose metabolism, and mitochondrial biogenesis using rodent model. The results showed significant increase in physical performance in cobalt supplemented rats without (two times) or with training (3.3 times) as compared to control animals. CoCl{sub 2} supplementation in rats augmented the biological activities of enzymes of TCA cycle, glycolysis and cytochrome c oxidase (COX); and increased the expression of glucose transporter-1 (Glut-1) in muscle showing increased glucose metabolism by aerobic respiration. There was also an increase in mitochondrial biogenesis in skeletal muscle observed by increased mRNA expressions of mitochondrial biogenesis markers which was further confirmed by electron microscopy. Moreover, nitric oxide production increased in skeletal muscle in cobalt supplemented rats, which seems to be the major reason for peroxisome proliferator activated receptor-gamma coactivator-1α (PGC-1α) induction and mitochondrial biogenesis. Thus, in conclusion, we state that hypoxia preconditioning by CoCl{sub 2} supplementation in rats increases mitochondrial biogenesis, glucose uptake and metabolism by aerobic respiration in skeletal muscle, which leads to increased physical performance. The significance of this study lies in understanding the molecular mechanism of hypoxia adaptation and improvement of work performance in normal as well as extreme conditions like hypoxia via hypoxia preconditioning. -- Highlights: ► We supplemented rats with CoCl{sub 2} for 15 days along with training. ► Co

Augmentation of aerobic respiration and mitochondrial biogenesis in skeletal muscle by hypoxia preconditioning with cobalt chloride

International Nuclear Information System (INIS)

Saxena, Saurabh; Shukla, Dhananjay; Bansal, Anju

2012-01-01

High altitude/hypoxia training is known to improve physical performance in athletes. Hypoxia induces hypoxia inducible factor-1 (HIF-1) and its downstream genes that facilitate hypoxia adaptation in muscle to increase physical performance. Cobalt chloride (CoCl 2 ), a hypoxia mimetic, stabilizes HIF-1, which otherwise is degraded in normoxic conditions. We studied the effects of hypoxia preconditioning by CoCl 2 supplementation on physical performance, glucose metabolism, and mitochondrial biogenesis using rodent model. The results showed significant increase in physical performance in cobalt supplemented rats without (two times) or with training (3.3 times) as compared to control animals. CoCl 2 supplementation in rats augmented the biological activities of enzymes of TCA cycle, glycolysis and cytochrome c oxidase (COX); and increased the expression of glucose transporter-1 (Glut-1) in muscle showing increased glucose metabolism by aerobic respiration. There was also an increase in mitochondrial biogenesis in skeletal muscle observed by increased mRNA expressions of mitochondrial biogenesis markers which was further confirmed by electron microscopy. Moreover, nitric oxide production increased in skeletal muscle in cobalt supplemented rats, which seems to be the major reason for peroxisome proliferator activated receptor-gamma coactivator-1α (PGC-1α) induction and mitochondrial biogenesis. Thus, in conclusion, we state that hypoxia preconditioning by CoCl 2 supplementation in rats increases mitochondrial biogenesis, glucose uptake and metabolism by aerobic respiration in skeletal muscle, which leads to increased physical performance. The significance of this study lies in understanding the molecular mechanism of hypoxia adaptation and improvement of work performance in normal as well as extreme conditions like hypoxia via hypoxia preconditioning. -- Highlights: ► We supplemented rats with CoCl 2 for 15 days along with training. ► CoCl 2 supplementation

Effects of calcium, calcium entry blockers and calmodulin inhibitors on atrioventricular conduction disturbances induced by hypoxia.

OpenAIRE

Anno, T.; Kodama, I.; Shibata, S.; Toyama, J.; Yamada, K.

1986-01-01

Effects of hypoxia on atrioventricular conduction were investigated in the Langendorff-perfused isolated heart of the rabbit with various extracellular calcium concentrations ([Ca2+]) as well as in the presence of verapamil, nifedipine, N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide (W-7) and chlorpromazine. The prolongation of the atrio-His (AH) interval by hypoxia for 7 min was greater with increasing [Ca2+]o ranging from 1.2 to 5.2 mM. At [Ca2+]o of over 3.2 mM under hypoxic condition...

[Study on the effect of promoting intelligence development and preventing hypoxia/reoxygenation injury of selenium-banqiao-Codonopsis pilosula-overground part in mice].

Science.gov (United States)

Xiao, Benjian; Chen, Guodong; Lan, Zongping

2005-08-01

To study on the effect of promoting intelligence development and preventing Hypoxia/Reoxygenation injury of Selenium-Banqiao-Codonopsis pilosula-overground part in mice. Promoting Intelligence Development experiment was induced by PIA; Hypoxia/reoxygenation ingury model was established to observe the activity of ROS, SOD, MOD and CAT in blood. Selenium-Banqiao-Codonopsis pilosula-overground part could enhance the learning and memory ability of old mice and obviously extend the swimming time of mice. It could also decrease the quality of ROS and MDA, increase the activity of SOD, but no significant effect on CAT. Selenium-Banqiao-Codonopsis pilosula-overground part has effect on promoting intelligence development and preventing hypoxia/reoxygenation injury.

NF-κB-dependent transcriptional upregulation of cyclin D1 exerts cytoprotection against hypoxic injury upon EGFR activation

International Nuclear Information System (INIS)

Chen, Zhi-Dong; Xu, Liang; Tang, Kan-Kai; Gong, Fang-Xiao; Liu, Jing-Quan; Ni, Yin; Jiang, Ling-Zhi; Hong, Jun; Han, Fang; Li, Qian; Yang, Xiang-Hong; Sun, Ren-Hua; Mo, Shi-Jing

2016-01-01

Apoptosis of neural cells is one of the main pathological features in hypoxic/ischemic brain injury. Nuclear factor-κB (NF-κB) might be a potential therapeutic target for hypoxic/ischemic brain injury since NF-κB has been found to be inactivated after hypoxia exposure, yet the underlying molecular mechanisms of NF-κB inactivation are largely unknown. Here we report that epidermal growth factor receptor (EGFR) activation prevents neuron-like PC12 cells apoptosis in response to hypoxia via restoring NF-κB-dependent transcriptional upregulation of cyclin D1. Functionally, EGFR activation by EGF stimulation mitigates hypoxia-induced PC12 cells apoptosis in both dose- and time-dependent manner. Of note, EGFR activation elevates IKKβ phosphorylation, increases IκBα ubiquitination, promotes P65 nuclear translocation and recruitment at cyclin D1 gene promoter as well as upregulates cyclin D1 expression. EGFR activation also abrogates the decrease of IKKβ phosphorylation, reduction of IκBα ubiquitination, blockade of P65 nuclear translocation and recruitment at cyclin D1 gene promoter as well as downregulation of cyclin D1 expression induced by hypoxia. Furthermore, NF-κB-dependent upregulation of cyclin D1 is instrumental for the EGFR-mediated cytoprotection against hypoxic apoptosis. In addition, the dephosphorylation of EGFR induced by either EGF siRNA transfection or anti-HB-EGF neutralization antibody treatment enhances hypoxic cytotoxicity, which are attenuated by EGF administration. Our results highlight the essential role of NF-κB-dependent transcriptional upregulation of cyclin D1 in EGFR-mediated cytoprotective effects under hypoxic preconditioning and support further investigation of EGF in clinical trials of patients with hypoxic/ischemic brain injury. - Highlights: • EGFR activation significantly decreases hypoxia-induced PC12 cells injury. • EGFR activation abrogates the transcriptional repression of cyclin D1 induced by hypoxia in a NF

NF-κB-dependent transcriptional upregulation of cyclin D1 exerts cytoprotection against hypoxic injury upon EGFR activation

Energy Technology Data Exchange (ETDEWEB)

Chen, Zhi-Dong [Department of Critical Care Medicine, The First Affiliated Hospital of Huzhou Normal College, Huzhou 313000, Zhejiang (China); Xu, Liang [Department of Critical Care Medicine, Zhejiang Provincial People’s Hospital, Hangzhou 310000, Zhejiang (China); Tang, Kan-Kai [Department of Critical Care Medicine, The First Affiliated Hospital of Huzhou Normal College, Huzhou 313000, Zhejiang (China); Gong, Fang-Xiao; Liu, Jing-Quan; Ni, Yin; Jiang, Ling-Zhi; Hong, Jun; Han, Fang; Li, Qian; Yang, Xiang-Hong [Department of Critical Care Medicine, Zhejiang Provincial People’s Hospital, Hangzhou 310000, Zhejiang (China); Sun, Ren-Hua, E-mail: jqin168@hotmail.com [Department of Critical Care Medicine, Zhejiang Provincial People’s Hospital, Hangzhou 310000, Zhejiang (China); Mo, Shi-Jing, E-mail: msj860307@163.com [Department of Critical Care Medicine, Zhejiang Provincial People’s Hospital, Hangzhou 310000, Zhejiang (China)

2016-09-10

Apoptosis of neural cells is one of the main pathological features in hypoxic/ischemic brain injury. Nuclear factor-κB (NF-κB) might be a potential therapeutic target for hypoxic/ischemic brain injury since NF-κB has been found to be inactivated after hypoxia exposure, yet the underlying molecular mechanisms of NF-κB inactivation are largely unknown. Here we report that epidermal growth factor receptor (EGFR) activation prevents neuron-like PC12 cells apoptosis in response to hypoxia via restoring NF-κB-dependent transcriptional upregulation of cyclin D1. Functionally, EGFR activation by EGF stimulation mitigates hypoxia-induced PC12 cells apoptosis in both dose- and time-dependent manner. Of note, EGFR activation elevates IKKβ phosphorylation, increases IκBα ubiquitination, promotes P65 nuclear translocation and recruitment at cyclin D1 gene promoter as well as upregulates cyclin D1 expression. EGFR activation also abrogates the decrease of IKKβ phosphorylation, reduction of IκBα ubiquitination, blockade of P65 nuclear translocation and recruitment at cyclin D1 gene promoter as well as downregulation of cyclin D1 expression induced by hypoxia. Furthermore, NF-κB-dependent upregulation of cyclin D1 is instrumental for the EGFR-mediated cytoprotection against hypoxic apoptosis. In addition, the dephosphorylation of EGFR induced by either EGF siRNA transfection or anti-HB-EGF neutralization antibody treatment enhances hypoxic cytotoxicity, which are attenuated by EGF administration. Our results highlight the essential role of NF-κB-dependent transcriptional upregulation of cyclin D1 in EGFR-mediated cytoprotective effects under hypoxic preconditioning and support further investigation of EGF in clinical trials of patients with hypoxic/ischemic brain injury. - Highlights: • EGFR activation significantly decreases hypoxia-induced PC12 cells injury. • EGFR activation abrogates the transcriptional repression of cyclin D1 induced by hypoxia in a NF

Acute physical exercise under hypoxia improves sleep, mood and reaction time.

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de Aquino-Lemos, Valdir; Santos, Ronaldo Vagner T; Antunes, Hanna Karen Moreira; Lira, Fabio S; Luz Bittar, Irene G; Caris, Aline V; Tufik, Sergio; de Mello, Marco Tulio

2016-02-01

This study aimed to assess the effect of two sessions of acute physical exercise at 50% VO2peak performed under hypoxia (equivalent to an altitude of 4500 m for 28 h) on sleep, mood and reaction time. Forty healthy men were randomized into 4 groups: Normoxia (NG) (n = 10); Hypoxia (HG) (n = 10); Exercise under Normoxia (ENG) (n = 10); and Exercise under Hypoxia (EHG) (n = 10). All mood and reaction time assessments were performed 40 min after awakening. Sleep was reassessed on the first day at 14 h after the initiation of hypoxia; mood and reaction time were measured 28 h later. Two sessions of acute physical exercise at 50% VO2peak were performed for 60 min on the first and second days after 3 and 27 h, respectively, after starting to hypoxia. Improved sleep efficiency, stage N3 and REM sleep and reduced wake after sleep onset were observed under hypoxia after acute physical exercise. Tension, anger, depressed mood, vigor and reaction time scores improved after exercise under hypoxia. We conclude that hypoxia impairs sleep, reaction time and mood. Acute physical exercise at 50% VO2peak under hypoxia improves sleep efficiency, reversing the aspects that had been adversely affected under hypoxia, possibly contributing to improved mood and reaction time.

Involvement of NMDA receptors in the antidepressant-like effect of tramadol in the mouse forced swimming test.

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Ostadhadi, Sattar; Norouzi-Javidan, Abbas; Chamanara, Mohsen; Akbarian, Reyhaneh; Imran-Khan, Muhammad; Ghasemi, Mehdi; Dehpour, Ahmad-Reza

2017-09-01

Tramadol is an analgesic agent that is mainly used to treat moderate to severe pain. There is evidence that tramadol may have antidepressant property. However, the mechanisms underlying the antidepressant effects of tramadol have not been elucidated yet. Considering that fact that N-methyl-d-aspartate (NMDA) receptor signaling may play an important role in the pathophysiology of depression, the aim of the present study was to investigate the role of NMDA receptor signaling in the possible antidepressant-like effects of tramadol in the mouse forced swimming test (mFST). We found that tramadol exerted antidepressant-like effects at high dose (40mg/kg, intraperitoneally [i.p.]) in the mFST. Co-administration of non-effective doses of NMDA receptor antagonists (ketamine [1mg/kg, i.p.], MK-801 [0.05mg/kg, i.p.], or magnesium sulfate [10mg/kg, i.p.]) with sub-effective dose of tramadol (20mg/kg, i.p.) exerted significant antidepressant-like effects in the mFST. The antidepressant-like effects of tramadol (40mg/kg) was also inhibited by pre-treatment with non-effective dose of the NMDA receptor agonist NMDA (75mg/kg, i.p.). Our data suggest a role for NMDA receptor signaling in the antidepressant-like effects of tramadol in the mFST. Copyright © 2017 Elsevier Inc. All rights reserved.

Hypoxia-Related Hormonal Appetite Modulation in Humans during Rest and Exercise: Mini Review

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Tadej Debevec

2017-05-01

Full Text Available Obesity is associated with numerous chronic ailments and represents one of the major health and economic issues in the modernized societies. Accordingly, there is an obvious need for novel treatment approaches. Recently, based on the reports of reduced appetite and subsequent weight loss following high-altitude sojourns, exposure to hypoxia has been proposed as a viable weight-reduction strategy. While altitude-related appetite modulation is complex and not entirely clear, hypoxia-induced alterations in hormonal appetite modulation might be among the key underlying mechanisms. The present paper summarizes the up-to-date research on hypoxia/altitude-induced changes in the gut and adipose tissue derived peptides related to appetite regulation. Orexigenic hormone ghrelin and anorexigenic peptides leptin, glucagon-like peptide-1, peptide YY, and cholecystokinin have to-date been investigated as potential modulators of hypoxia-driven appetite alterations. Current evidence suggests that hypoxia can, especially acutely, lead to decreased appetite, most probably via reduction of acylated ghrelin concentration. Hypoxia-related short and long-term changes in other hormonal markers are more unclear although hypoxia seems to importantly modulate leptin levels, especially following prolonged hypoxic exposures. Limited evidence also suggests that different activity levels during exposures to hypoxia do not additively affect hormonal appetite markers. Although very few studies have been performed in obese/overweight individuals, the available data indicate that hypoxia/altitude exposures do not seem to differentially affect appetite regulation via hormonal pathways in this cohort. Given the lack of experimental data, future well-controlled acute and prolonged studies are warranted to expand our understanding of hypoxia-induced hormonal appetite modulation and its kinetics in health and disease.

Preeclampsia, Hypoxia, Thrombosis, and Inflammation

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Amir A. Shamshirsaz

2012-01-01

Full Text Available Reductions in uteroplacental flow initiate a cascade of molecular effects leading to hypoxia, thrombosis, inflammation, and endothelial cell dysfunction resulting in untoward pregnancy outcomes. In this review, we detail these effects and their relationship to preeclampsia (PE and intrauterine growth restriction (IUGR.

Impaired histone deacetylases 5 and 6 expression mimics the effects of obesity and hypoxia on adipocyte function

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Julien Bricambert

2016-12-01

Full Text Available Objective: The goal of the study was to investigate the role of histone deacetylases (HDACs in adipocyte function associated with obesity and hypoxia. Methods: Total proteins and RNA were prepared from human visceral adipose tissues (VAT of human obese and normal weight subjects and from white adipose tissue (WAT of C57Bl6-Rj mice fed a normal or high fat diet (HFD for 16 weeks. HDAC activity was measured by colorimetric assay whereas the gene and protein expression were monitored by real-time PCR and by western blotting, respectively. RNA interference (RNAi was used to silence the expression of genes in 3T3-L1 adipocytes. Results: Total HDAC activity was decreased in VAT and WAT from obese individuals and from mice fed a HFD, respectively. The HDAC activity reduction was associated with decreased HDAC5/Hdac5 and HDAC6/Hdac6 expression in human and mice adipocyte fraction. Similarly, hypoxia hampered total Hdac activity and reduced the expression of Hdac5 and Hdac6 in 3T3-L1 adipocytes. The decrease of both Hdac5 and Hdac6 by hypoxia was associated with altered expression of adipokines and of the inducible cAMP early repressor (Icer, a key repressor that is defective in human and mice obesity. Silencing of Icer in adipocytes reproduced the changes in adipokine levels under hypoxia and obesity, suggesting a causative effect. Finally, modeling the defect of the two Hdacs in adipocytes by RNAi or selective inhibitors mimicked the effects of hypoxia on the expression of Icer, leading to impairment of insulin-induced glucose uptake. Conclusion: Hdac5 and Hdac6 expression are required for the adequate expression of Icer and adipocyte function. Altered adipose expression of the two Hdacs in obesity by hypoxia may contribute to the development of metabolic abnormalities. Keywords: Histone deacetylases, Adipocytes, Adipokines, Obesity, Insulin resistance

Absence of the inflammasome adaptor ASC reduces hypoxia-induced pulmonary hypertension in mice.

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Cero, Fadila Telarevic; Hillestad, Vigdis; Sjaastad, Ivar; Yndestad, Arne; Aukrust, Pål; Ranheim, Trine; Lunde, Ida Gjervold; Olsen, Maria Belland; Lien, Egil; Zhang, Lili; Haugstad, Solveig Bjærum; Løberg, Else Marit; Christensen, Geir; Larsen, Karl-Otto; Skjønsberg, Ole Henning

2015-08-15

Pulmonary hypertension is a serious condition that can lead to premature death. The mechanisms involved are incompletely understood although a role for the immune system has been suggested. Inflammasomes are part of the innate immune system and consist of the effector caspase-1 and a receptor, where nucleotide-binding oligomerization domain-like receptor pyrin domain-containing 3 (NLRP3) is the best characterized and interacts with the adaptor protein apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC). To investigate whether ASC and NLRP3 inflammasome components are involved in hypoxia-induced pulmonary hypertension, we utilized mice deficient in ASC and NLRP3. Active caspase-1, IL-18, and IL-1β, which are regulated by inflammasomes, were measured in lung homogenates in wild-type (WT), ASC(-/-), and NLRP3(-/-) mice, and phenotypical changes related to pulmonary hypertension and right ventricular remodeling were characterized after hypoxic exposure. Right ventricular systolic pressure (RVSP) of ASC(-/-) mice was significantly lower than in WT exposed to hypoxia (40.8 ± 1.5 mmHg vs. 55.8 ± 2.4 mmHg, P right ventricular remodeling. RVSP of NLRP3(-/-) mice exposed to hypoxia was not significantly altered compared with WT hypoxia. Whereas hypoxia increased protein levels of caspase-1, IL-18, and IL-1β in WT and NLRP3(-/-) mice, this response was absent in ASC(-/-) mice. Moreover, ASC(-/-) mice displayed reduced muscularization and collagen deposition around arteries. In conclusion, hypoxia-induced elevated right ventricular pressure and remodeling were attenuated in mice lacking the inflammasome adaptor protein ASC, suggesting that inflammasomes play an important role in the pathogenesis of pulmonary hypertension. Copyright © 2015 the American Physiological Society.

The Effects of Portulaca oleracea on Hypoxia-Induced Pulmonary Edema in Mice.

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Yue, Tan; Xiaosa, Wen; Ruirui, Qi; Wencai, Shi; Hailiang, Xin; Min, Li

2015-03-01

Portulaca oleracea L. (PO) is known as "a vegetable for long life" due to its antioxidant, anti-inflammatory, and other pharmacological activities. However, the protective activity of the ethanol extract of PO (EEPO) against hypoxia-induced pulmonary edema has not been fully investigated. In this study, we exposed mice to a simulated altitude of 7000 meters for 0, 3, 6, 9, and 12 h to observe changes in the water content and transvascular leakage of the mouse lung. It was found that transvascular leakage increased to the maximum in the mouse lung after 6 h exposure to hypobaric hypoxia. Prophylactic administration of EEPO before hypoxic exposure markedly reduced the transvascular leakage and oxidative stress, and inhibited the upregulation of NF-kB in the mouse lung, as compared with the control group. In addition, EEPO significantly reduced the levels of proinflammatory cytokines and cell adhesion molecules in the lungs of mice, as compared with the hypoxia group. Our results show that EEPO can reduce initial transvascular leakage and pulmonary edema under hypobaric hypoxia conditions.

Hypoxia induces epithelial-mesenchymal transition via activation of SNAI1 by hypoxia-inducible factor -1α in hepatocellular carcinoma

International Nuclear Information System (INIS)

Zhang, Lin; Feng, Xiaobin; Dong, Jiahong; Qian, Cheng; Huang, Gang; Li, Xiaowu; Zhang, Yujun; Jiang, Yan; Shen, Junjie; Liu, Jia; Wang, Qingliang; Zhu, Jin

2013-01-01

High invasion and metastasis are the primary factors causing poor prognosis of patients with hepatocellular carcinoma (HCC). However, the molecular mechanisms underlying these biological behaviors have not been completely elucidated. In this study, we investigate the molecular mechanism by which hypoxia promotes HCC invasion and metastasis through inducing epithelial-mesenchymal transition (EMT). The expression of EMT markers was analyzed by immunohistochemistry. Effect of hypoxia on induction of EMT and ability of cell migration and invasion were performed. Luciferase reporter system was used for evaluation of Snail regulation by hypoxia-inducible factor -1α (HIF-1α). We found that overexpression of HIF-1α was observed in HCC liver tissues and was related to poor prognosis of HCC patients. HIF-1α expression profile was correlated with the expression levels of SNAI1, E-cadherin, N-cadherin and Vimentin. Hypoxia was able to induce EMT and enhance ability of invasion and migration in HCC cells. The same phenomena were also observed in CoCl2-treated cells. The shRNA-mediated HIF-1α suppression abrogated CoCl2-induced EMT and reduced ability of migration and invasion in HCC cells. Luciferase assay showed that HIF-1α transcriptional regulated the expression of SNAI1 based on two hypoxia response elements (HREs) in SNAI1 promoter. We demonstrated that hypoxia-stabilized HIF1α promoted EMT through increasing SNAI1 transcription in HCC cells. This data provided a potential therapeutic target for HCC treatment

Epidermal growth factor receptor inhibition reduces angiogenesis via hypoxia-inducible factor-1α and Notch1 in head neck squamous cell carcinoma.

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Wei-Ming Wang

Full Text Available Angiogenesis, a marker of cancer development, affects response to radiotherapy sensibility. This preclinical study aims to understand the receptor tyrosine kinase-mediated angiogenesis in head neck squamous cell carcinoma (HNSCC. The receptor tyrosine kinase activity in a transgenic mouse model of HNSCC was assessed. The anti-tumorigenetic and anti-angiogenetic effects of cetuximab-induced epidermal growth factor receptor (EGFR inhibition were investigated in xenograft and transgenic mouse models of HNSCC. The signaling transduction of Notch1 and hypoxia-inducible factor-1α (HIF-1α was also analyzed. EGFR was overexpressed and activated in the Tgfbr1/Pten deletion (2cKO mouse model of HNSCC. Cetuximab significantly delayed tumor onset by reducing tumor angiogenesis. This drug exerted similar effects on heterotopic xenograft tumors. In the human HNSCC tissue array, increased EGFR expression correlated with increased HIF-1α and micro vessel density. Cetuximab inhibited tumor-induced angiogenesis in vitro and in vivo by significantly downregulating HIF-1α and Notch1. EGFR is involved in the tumor angiogenesis of HNSCC via the HIF-1α and Notch1 pathways. Therefore, targeting EGFR by suppressing hypoxia- and Notch-induced angiogenesis may benefit HNSCC therapy.

Salinity effects on behavioural response to hypoxia in the non-native Mayan cichlid Cichlasoma urophthalmus from Florida Everglades wetlands.

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Schofield, P J; Loftus, W F; Fontaine, J A

2009-04-01

This study quantified the hypoxia tolerance of the Mayan cichlid Cichlasoma urophthalmus over a range of salinities. The species was very tolerant of hypoxia, using aquatic surface respiration (ASR) and buccal bubble holding when oxygen tensions dropped to <20 mmHg (c. 1.0 mg l(-1)) and 6 mmHg, respectively. Salinity had little effect on the hypoxia tolerance of C. urophthalmus, except that bubble holding was more frequent at the higher salinities tested. Levels of aggression were greatest at the highest salinity. The ASR thresholds of C. urophthalmus were similar to native centrarchid sunfishes from the Everglades, however, aggression levels for C. uropthalmus were markedly higher.

Understanding and exploiting the genomic response to hypoxia

International Nuclear Information System (INIS)

Giaccia, A.J.

2003-01-01

The tumor microenvironment influences both therapeutic outcome and malignant progression. Of the many factors that may be altered in the tumor microenvironment, changes in tumor oxygenation have been strongly associated with a lower probability of local tumor control and survival. In vitro studies indicate that cells exposed to a low oxygen environment exhibit multiple phenotypes, including cell-cycle arrest, increased expression of pro-angiogenic genes, increased invasive capacity, increased apoptosis, increased anaerobic metabolism and altered differentiation programs. While the mechanistic basis of hypoxia as an impediment to radiotherapy and chemotherapy is well understood, it is unclear what changes in the cellular phenotype are important in understanding how hypoxia modifies malignant progression. One insight into how hypoxia modulates malignant progression comes from understanding the critical transcriptional regulators of gene expression under hypoxic conditions such as hypoxia inducible factor 1 (HIF-1) as well as changes in gene expression in untransformed and transformed cells. Overall, about 1.5% of the genome is found to be transcriptionally responsive to changes in oxygenation. Most importantly, the coordinated changes in gene expression under hypoxic conditions underscore the physiologic basis for altering gene expression in response to a low oxygen environment. In addition, some hypoxia-induced genes exhibit increased expression after reoxygenation, suggesting that they are regulated both by hypoxia and oxidative stress. Analysis of the genomic response to hypoxia has several therapeutic uses. First, it allows one to ask the question of what the cellular consequences are to inhibition of the transcriptional response to hypoxia such as by targeting the HIF-1 transcription factor. While the effect of loss of HIF-1 in tumors leads to inhibition of tumor growth, it does not eliminate tumors. In fact, studies indicate that inhibition of HIF-1 leads to a

Signaling hypoxia by hypoxia-inducible factor protein hydroxylases: a historical overview and future perspectives

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Bishop, Tammie; Ratcliffe, Peter J

2014-01-01

By the early 1900s, the close matching of oxygen supply with demand was recognized to be a fundamental requirement for physiological function, and multiple adaptive responses to environment hypoxia had been described. Nevertheless, the widespread operation of mechanisms that directly sense and respond to levels of oxygen in animal cells was not appreciated for most of the twentieth century with investigators generally stressing the regulatory importance of metabolic products. Work over the last 25 years has overturned that paradigm. It has revealed the existence of a set of “oxygen-sensing” 2-oxoglutarate dependent dioxygenases that catalyze the hydroxylation of specific amino acid residues and thereby control the stability and activity of hypoxia-inducible factor. The hypoxia-inducible factor hydroxylase pathway regulates a massive transcriptional cascade that is operative in essentially all animal cells. It transduces a wide range of responses to hypoxia, extending well beyond the classical boundaries of hypoxia physiology. Here we review the discovery and elucidation of these pathways, and consider the opportunities and challenges that have been brought into focus by the findings, including new implications for the integrated physiology of hypoxia and therapeutic approaches to ischemic/hypoxic disease. PMID:27774477

Anxiolytic-like effect of Sonchus oleraceus L. in mice.

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Cardoso Vilela, Fabiana; Soncini, Roseli; Giusti-Paiva, Alexandre

2009-07-15

Sonchus oleraceus L. has been used as a general tonic in Brazilian folk medicine. Nevertheless, available scientific information regarding this species is scarce; there are no reports related to its possible effect on the central nervous system. This study was conducted to establish the anxiolytic effect of extracts from the aerial parts of Sonchus oleraceus. This study evaluated the effect of hydroethanolic and dichloromethane extracts of Sonchus oleraceus in mice submitted to the elevated plus-maze and open-field tests. Clonazepam was used as the standard drug. In the elevated plus-maze test, the Sonchus oleraceus extracts increased the percentage of open arm entries (PSonchus oleraceus extract exerts an anxiolytic-like effect on mice.

Tumor Hypoxia: Causative Mechanisms, Microregional Heterogeneities, and the Role of Tissue-Based Hypoxia Markers.

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Vaupel, Peter; Mayer, Arnulf

Tumor hypoxia is a hallmark of solid malignant tumor growth, profoundly influences malignant progression and contributes to the development of therapeutic resistance. Pathogenesis of tumor hypoxia is multifactorial, with contributions from both acute and chronic factors. Spatial distribution of hypoxia within tumors is markedly heterogeneous and often changes over time, e.g., during a course of radiotherapy. Substantial changes in the oxygenation status can occur within the distance of a few cell layers, explaining the inability of currently used molecular imaging techniques to adequately assess this crucial trait. Due to the possible importance of tumor hypoxia for clinical decision-making, there is a great demand for molecular tools which may provide the necessary resolution down to the single cell level. Exogenous and endogenous markers of tumor hypoxia have been investigated for this purpose. Their potential use may be greatly enhanced by multiparametric in situ methods in experimental and human tumor tissue.

Modelling and simulation of the influence of acute and chronic hypoxia on [18F]fluoromisonidazole PET imaging.

NARCIS (Netherlands)

Monnich, D.; Troost, E.G.C.; Kaanders, J.H.A.M.; Oyen, W.J.G.; Alber, M.; Thorwarth, D.

2012-01-01

Tumour hypoxia can be assessed by positron emission tomography (PET) using radiotracers like [(18)F]fluoromisonidazole (Fmiso). The purpose of this work was to independently investigate the influence of chronic and acute hypoxia on the retention of Fmiso on the microscale. This was approached by

[The limitation of glucose catabolism as a factor in protection during hypoxia].

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Burbello, A T; Vishvtseva, V V; Denisenko, P P; Safonova, A F; Dobrokhotova, E G

1995-01-01

Violuric acid was first shown to have antihypoxic and antioxidative properties, to exert protective action in sodium nitrite-induced hemic hypoxia. Hepatic glucose and glucogen levels increased, the activity of glucose-6- phosphodihydrogenase enhanced, while that of lactate dehydrogenase and alkaline phosphatase decreased, the content of cAMP restored, whereas cGMP and 2,3-diphosphoglycerate levels decreased to a greater extent. The action of violuric acid was especially evident at the ultrastructural level-the ultrastructure of brush receptor elements in anoxia in the presence of violuric acid's action retained all the features characteristic for intact animals, which was accompanied by a significant accumulation of glycogen in the neuroplasm.

Hypoxia-Inducible Factor-1 as a Therapeutic Target in Endometrial Cancer Management

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Laura M. S. Seeber

2010-01-01

Full Text Available In the Western world, endometrial cancer (EC is the most common malignant tumor of the female genital tract. Solid tumors like EC outgrow their vasculature resulting in hypoxia. Tumor hypoxia is important because it renders an aggressive phenotype and leads to radio- and chemo-therapy resistance. Hypoxia-inducible factor-1 (HIF-1 plays an essential role in the adaptive cellular response to hypoxia and is associated with poor clinical outcome in EC. Therefore, HIF-1 could be an attractive therapeutic target. Selective HIF-1 inhibitors have not been identified. A number of nonselective inhibitors which target signaling pathways upstream or downstream HIF-1 are known to decrease HIF-1 protein levels. In clinical trials for the treatment of advanced and/or recurrent EC are the topoisomerase I inhibitor Topotecan, mTOR-inhibitor Rapamycin, and angiogenesis inhibitor Bevacizumab. Preliminary data shows encouraging results for these agents. Further work is needed to identify selective HIF-1 inhibitors and to translate these into clinical trials.

Fisetin exerts antihyperalgesic effect in a mouse model of neuropathic pain: engagement of spinal serotonergic system

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Zhao, Xin; Wang, Chuang; Cui, Wu-Geng; Ma, Qing; Zhou, Wen-Hua

2015-01-01

Fisetin, a natural flavonoid, has been shown in our previous studies to exert antidepressant-like effect. As antidepressant drugs are clinically used to treat chronic neuropathic pain, this work aimed to investigate the potential antinociceptive efficacies of fisetin against neuropathic pain and explore mechanism(s). We subjected mice to chronic constriction injury (CCI) by loosely ligating the sciatic nerves, and Hargreaves test or von Frey test was used to assess thermal hyperalgesia or mechanical allodynia, respectively. Chronic fisetin treatment (5, 15 or 45 mg/kg, p.o.) ameliorated thermal hyperalgesia (but not mechanical allodynia) in CCI mice, concomitant with escalated levels of spinal monoamines and suppressed monoamine oxidase (MAO)-A activity. The antihyperalgesic action of fisetin was abolished by chemical depletion of spinal serotonin (5-HT) but potentiated by co-treatment with 5-HTP, a precursor of 5-HT. Moreover, intraperitoneal (i.p.) or intrathecal (i.t.) co-treatment with 5-HT7 receptor antagonist SB-258719 completely abrogated fisetin's antihyperalgesia. These findings confirm that chronic fisetin treatment exerts antinociceptive effect on thermal hyperalgesia in neuropathic mice, with spinal serotonergic system (coupled with 5-HT7) being critically involved. Of special benefit, fisetin attenuated co-morbidly behavioral symptoms of depression and anxiety (evaluated in forced swim test, novelty suppressed feeding test and light-dark test) evoked by neuropathic pain. PMID:25761874

Mouse Intermittent Hypoxia Mimicking Apnea of Prematurity: Effects on Myelinogenesis and Axonal Maturation

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CAI, JUN; TUONG, CHI MINH; ZHANG, YIPING; SHIELDS, CHRISTOPHER B.; GUO, GANG; FU, HUI; GOZAL, DAVID

2014-01-01

Premature babies are at high risk for both infantile apnea and long-term neurobehavioral deficits. Recent studies suggest that diffuse structural changes in brain white matter are a positive predictor of poor cognitive outcomes. Since oligodendrocyte maturation, myelination, axon development and synapse formation mainly occur in the 3rd trimester of gestation and 1st postnatal year, infantile apnea could lead to and/or exaggerate white matter impairments in preterm neonates. Therefore, we investigated oligodendroglia and axon development in a neonatal mouse model of intermittent hypoxia between postnatal days 2 to 10. During critical phases of central nervous system development, intermittent hypoxia induced hypomyelination in the corpus callosum, striatum, fornix and cerebellum, but not the pons or spinal cord. Intermittent hypoxia-elicited alterations in myelin-forming processes were reflected by decreased expression of myelin proteins, including MBP, PLP, MAG and CNPase, possibly due to arrested maturation of oligodendrocytes. Ultra-structural abnormalities were apparent in the myelin sheath and axon. Immature oligodendrocytes were more vulnerable to neonatal intermittent hypoxia exposures than developing axons, suggesting that hypomyelination may contribute, at least partially, to axonal deficits. Insufficient neurofilament synthesis with anomalous components of neurofilament subunits, β-tubulin and MAP2 isoforms indicated immaturity of axons in intermittent hypoxia-exposed mouse brains. In addition, down-regulation of Synapsin I, Synaptophysin and Gap-43 phosphorylation suggested a potential stunt in axonogenesis and synaptogenesis. The region-selective and complex impairment in brain white matter induced by intermittent hypoxia was further associated with electrophysiological changes that may underlie long-term neurobehavioral sequelae. PMID:21953180

Effect of hypoxia on the activity and binding of glycolytic and associated enzymes in sea scorpion tissues

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Lushchak V.I.

1998-01-01

Full Text Available The effect of hypoxia on the levels of glycogen, glucose and lactate as well as the activities and binding of glycolytic and associated enzymes to subcellular structures was studied in brain, liver and white muscle of the teleost fish, Scorpaena porcus. Hypoxia exposure decreased glucose levels in liver from 2.53 to 1.70 µmol/g wet weight and in muscle led to its increase from 3.64 to 25.1 µmol/g wet weight. Maximal activities of several enzymes in brain were increased by hypoxia: hexokinase by 23%, phosphoglucoisomerase by 47% and phosphofructokinase (PFK by 56%. However, activities of other enzymes in brain as well as enzymes in liver and white muscle were largely unchanged or decreased during experimental hypoxia. Glycolytic enzymes in all three tissues were partitioned between soluble and particulate-bound forms. In several cases, the percentage of bound enzymes was reduced during hypoxia; bound aldolase in brain was reduced from 36.4 to 30.3% whereas glucose-6-phosphate dehydrogenase fell from 55.7 to 28.7% bound. In muscle PFK was reduced from 57.4 to 41.7% bound. Oppositely, the proportion of bound aldolase and triosephosphate isomerase increased in hypoxic muscle. Phosphoglucomutase did not appear to occur in a bound form in liver and bound phosphoglucomutase disappeared in muscle during hypoxia exposure. Anoxia exposure also led to the disappearance of bound fructose-1,6-bisphosphatase in liver, whereas a bound fraction of this enzyme appeared in white muscle of anoxic animals. The possible function of reversible binding of glycolytic enzymes to subcellular structures as a regulatory mechanism of carbohydrate metabolism is discussed.

Andrographolide inhibits hypoxia-induced hypoxia-inducible factor 1α and endothelin 1 expression through the heme oxygenase 1/CO/cGMP/MKP-5 pathways in EA.hy926 cells.

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Lin, Hung-Chih; Su, Shih-Li; Lin, Wan-Chun; Lin, Ai-Hsuan; Yang, Ya-Chen; Lii, Chong-Kuei; Chen, Haw-Wen

2018-03-01

Andrographolide is a potent anti-inflammatory agent found in Andrographis paniculata. Endothelin 1 (ET-1) is an endothelium-derived vasoconstrictor with pro-inflammatory properties secreted in response to hypoxia. Mitogen-activated protein kinase phosphatase 5 (MKP-5) is a dual-specificity phosphatase that dephosphorylates threonine and tyrosine residues of MAPKs. We showed previously that hypoxia-induced HIF-1α expression and ET-1 secretion are dependent on p38 MAPK in EA.hy926 cells. Here, we investigate what role MKP-5 plays in andrographolide's inhibition of hypoxia-induced expression of HIF-1α and ET-1. Hypoxic conditions were created using the hypoxia-mimetic agent CoCl 2 . Andrographolide enhanced HO-1 and MKP-5 expression and cellular cGMP content in addition to inhibiting hypoxia-induced ROS generation. Concomitantly, the HO-1 byproduct CO and the cGMP analogue 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) increased MKP-5 expression, and pretreatment with CO and 8-Br-cGMP inhibited hypoxia-induced HIF-1α and ET-1 expression. Transfection of HO-1 siRNA or pretreatment with the HO-1 inhibitor ZnPP-9 or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, a specific inhibitor of soluble guanylate cyclase, reduced andrographolide-induced MKP-5 expression. Moreover, silencing MKP-5 or treatment with the phosphatase inhibitor vanadate abrogated andrographolide's suppressing hypoxia-induced p38 MAPK activation and HIF-1α expression. The inhibition of hypoxia-induced HIF-1α and ET-1 expression by andrographolide is likely associated with HO-1/CO/cGMP/MKP-5 pathways, which is involved in inhibiting hypoxia-induced p38 MAPK activation. © 2017 Wiley Periodicals, Inc.

Radiosensitive effect of hypoxia-inducible factor 1α inhibitor YC-1 on hypoxic glioma SHG44 cell line

International Nuclear Information System (INIS)

Guo Xinwei; Lu Xueguan; Tong Liumei; Zong Tianzhou; Chen Liesong

2011-01-01

Objective: To investigate the radiosensitive effect of hypoxia-inducible factor 1α (HIF-1α) inhibitor YC-1 on hypoxic glioma SHG44 cell line and its related mechanism. Methods: Glioma SHG44 cell line was cultured in normoxic (20% O 2 ), continuous hypoxia (1% O 2 ) for 12 h and 24 h, continuous hypoxia plus YC-1 was performed for 12 h and 24 h, respectively. The expression of HIF-1α was assessed by Western blot. The radiosensitivity was evaluated by the survival curve, and the sublethal damage repair (SLDR) ability was measured by dose-fraction experiment. Results: HIF-1α protein levels of glioma SHG44 cells were significantly increased after hypoxic cultures for 12 h and 24 h than those of the corresponding cells cultured in normoxic, while the radiosensitivity was lower. The OER (oxygen-enhancement ratio) of SHG44 cells in hypoxia for 12 h and 24 h were 1.22 and 1.37, respectively. By the further statistical analysis it was found that SLDR ability of glioma SHG44 was increased at hypoxia, and when irradiation was carried one at the interval of 8, 10, 12 h it was statistically significant (P<0.05). HIF-1α protein levels of glioma SHG44 cells cultured in hypoxia plus YC-1 for 12 h and 24 h were decreased significantly compared to the corresponding cells cultured in hypoxia only, while the radiosensitivity was significantly increased. the EF (enhancement factor) of YC-1 for glioma SHG44 cells at hypoxia for 12 h and 24 h was 1.27. By the further statistical analysis it was also found that SLDR ability was decreased significantly for hypoxic SHG44 cells which was co-cultured with YC-1, and at the interval of 8, 10, 12 h irradiation was statistically significant (P<0.05). Conclusion: YC-1 can increase the radiosensitivity of hypoxic glioma SHG44 cell line, and its mechanism is related to SLDR inhibited by YC-1. (authors)

Increased oxidative stress and anaerobic energy release, but blunted Thr172-AMPKα phosphorylation, in response to sprint exercise in severe acute hypoxia in humans.

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Morales-Alamo, David; Ponce-González, Jesús Gustavo; Guadalupe-Grau, Amelia; Rodríguez-García, Lorena; Santana, Alfredo; Cusso, Maria Roser; Guerrero, Mario; Guerra, Borja; Dorado, Cecilia; Calbet, José A L

2012-09-01

AMP-activated protein kinase (AMPK) is a major mediator of the exercise response and a molecular target to improve insulin sensitivity. To determine if the anaerobic component of the exercise response, which is exaggerated when sprint is performed in severe acute hypoxia, influences sprint exercise-elicited Thr(172)-AMPKα phosphorylation, 10 volunteers performed a single 30-s sprint (Wingate test) in normoxia and in severe acute hypoxia (inspired Po(2): 75 mmHg). Vastus lateralis muscle biopsies were obtained before and immediately after 30 and 120 min postsprint. Mean power output and O(2) consumption were 6% and 37%, respectively, lower in hypoxia than in normoxia. O(2) deficit and muscle lactate accumulation were greater in hypoxia than in normoxia. Carbonylated skeletal muscle and plasma proteins were increased after the sprint in hypoxia. Thr(172)-AMPKα phosphorylation was increased by 3.1-fold 30 min after the sprint in normoxia. This effect was prevented by hypoxia. The NAD(+)-to-NADH.H(+) ratio was reduced (by 24-fold) after the sprints, with a greater reduction in hypoxia than in normoxia (P exercise in human skeletal muscle is altered in severe acute hypoxia, which abrogated Thr(172)-AMPKα phosphorylation, likely due to lower LKB1 activation by SIRT1.

The histone demethylases JMJD1A and JMJD2B are transcriptional targets of hypoxia-inducible factor HIF

DEFF Research Database (Denmark)

Beyer, Sophie; Kristensen, Malene Maag; Jensen, Kim Steen

2008-01-01

of these modifications is exerted by histone methyltransferases and the recently discovered histone demethylases. Here we show that the hypoxia-inducible factor HIF-1a binds to specific recognition sites in the genes encoding the jumonji family histone demethylases JMJD1A and JMJD2B and induces their expression....... Accordingly, hypoxic cells express elevated levels of JMJD1A and JMJD2B mRNA and protein. Furthermore, we find increased expression of JMJD1A and JMJD2B in renal cancer cells that have lost the von Hippel Lindau tumor suppressor protein VHL and therefore display a deregulated expression of HIF. Studies...... on ectopically expressed JMJD1A and JMJD2B indicate that both proteins retain their histone lysine demethylase activity in hypoxia and thereby might impact the hypoxic gene expression program....

The Expression of HMGB1 in Bone Marrow MSCs Is Upregulated by Hypoxia with Regulatory Effects on the Apoptosis and Adhesion

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Mei-Yun Tan

2016-01-01

Full Text Available Background and Aims. Hypoxia regulates the survival of mesenchymal stem cells (MSCs but the mechanism is unclear. In hypoxia, the level of high mobility group box 1 (HMGB1 was increased in many cells which may be involved in the regulation of cell biology. The aim is to determine whether hypoxia affects the expression of HMGB1 in bone marrow MSCs (BM-MSCs and to investigate the role of HMGB1 in the apoptosis and adhesion. Methods. BM-MSCs were exposed to hypoxia (1% O2 and normoxia (20% O2 and the expression of HMGB1 was measured by RT-PCR and western blotting. The apoptosis and adhesion of BM-MSCs were evaluated after interfered by different concentrations of HMGB1. Results. Expression of HMGB1 in BM-MSCs showed a significant upregulation in hypoxia when compared to those in normoxia. The adhesion of BM-MSCs was increased by HMGB1 in a concentration-dependent manner; the apoptosis effect of HMGB1 depended on its concentrations: HMGB1 at low concentration (50 ng/mL promoted the apoptosis of BM-MSCs while HMGB1 at high concentration (≥100 ng/mL reduced this apoptosis. Conclusions. Hypoxia enhanced the expression of HMGB1 in BM-MSCs with influences on apoptosis and adhesion and this could have a significant effect on the regenerative potential of MSC-based strategies.

Copper alters hypoxia sensitivity and the behavioural emersion response in the amphibious fish Kryptolebias marmoratus.

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Blewett, Tamzin A; Simon, Robyn A; Turko, Andy J; Wright, Patricia A

2017-08-01

Elevated levels of metals have been reported in mangrove ecosystems worldwide. Mangrove fishes also routinely experience severe environmental stressors, such as hypoxia. In the amphibious fish Kryptolebias marmoratus (mangrove rivulus), a key behavioural response to avoid aquatic stress is to leave water (emersion). We hypothesized that copper (Cu) exposure would increase the sensitivity of this behavioural hypoxia avoidance response due to histopathological effects of Cu on gill structure and function. K. marmoratus were exposed to either control (no added Cu) or Cu (300μg/L) for 96h. Following this period, fish were exposed to an acute hypoxic challenge (decline in dissolved oxygen to ∼0% over 15min), and the emersion response was recorded. Gills were examined for histological changes. Fish exposed to Cu emersed at a higher dissolved oxygen level (7.5±0.6%), relative to the control treatment group (5.8±0.4%). Histological analysis showed that the gill surface area increased and the interlamellar cell mass (ILCM) was reduced following Cu exposure, contrary to our prediction. Overall, these data indicate that Cu induces hypoxia-like changes to gill morphology and increases the sensitivity of the hypoxia emersion response. Copyright © 2017 Elsevier B.V. All rights reserved.

Modulation of Radioprotective Effects of Respiratory Hypoxia by Changing the Duration of Hypoxia before Irradiation and by Combining Hypoxia and Administration of Hemopoiesis-Stimulating Agents

Czech Academy of Sciences Publication Activity Database

Vacek, Antonín; Tačev, T.; Hofer, Michal

2001-01-01

Roč. 177, č. 9 (2001), s. 474-481 ISSN 0179-7158 Institutional research plan: CEZ:AV0Z5004920 Keywords : radioprotection * mice * hypoxia Subject RIV: BO - Biophysics Impact factor: 3.005, year: 2001

Selective vulnerability in brain hypoxia

DEFF Research Database (Denmark)

Cervos-Navarro, J.; Diemer, Nils Henrik

1991-01-01

Neuropathology, selective vulnerability, brain hypoxia, vascular factors, excitotoxicity, ion homeostasis......Neuropathology, selective vulnerability, brain hypoxia, vascular factors, excitotoxicity, ion homeostasis...

Hypoxia regulates the expression of the neuromedin B receptor through a mechanism dependent on hypoxia-inducible factor-1α.

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Hyun-Joo Park

Full Text Available The neuromedin B receptor (NMB-R, a member of the mammalian bombesin receptor family, is frequently overexpressed in various tumors. In the present study, we found that exposure to hypoxic conditions increases the levels of NMBR mRNA and protein in breast cancer cells, which are tightly regulated by hypoxia-inducible factor-1α (HIF-1α. We confirmed the effect of HIF-1α on NMBR transcription by performing an NMBR promoter-driven reporter assay and then identified a functional hypoxia-responsive element (HRE in the human NMBR promoter region. Further, the binding of HIF-1α to the NMBR promoter was corroborated by electrophoretic mobility shift and chromatin immunoprecipitation assays, which showed that HIF-1α specifically and directly bound to the NMBR promoter in response to hypoxia. Immunohistochemical analysis of a xenograft and a human breast cancer tissue array revealed a significant correlation between NMB-R and HIF-1α expression. Taken together, our findings indicate that hypoxia induces NMB-R expression through a novel mechanism to regulate HIF-1α expression in breast cancer cells.

Effect of acute hypoxia on cognition: A systematic review and meta-regression analysis.

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McMorris, Terry; Hale, Beverley J; Barwood, Martin; Costello, Joseph; Corbett, Jo

2017-03-01

A systematic meta-regression analysis of the effects of acute hypoxia on the performance of central executive and non-executive tasks, and the effects of the moderating variables, arterial partial pressure of oxygen (PaO 2 ) and hypobaric versus normobaric hypoxia, was undertaken. Studies were included if they were performed on healthy humans; within-subject design was used; data were reported giving the PaO 2 or that allowed the PaO 2 to be estimated (e.g. arterial oxygen saturation and/or altitude); and the duration of being in a hypoxic state prior to cognitive testing was ≤6days. Twenty-two experiments met the criteria for inclusion and demonstrated a moderate, negative mean effect size (g=-0.49, 95% CI -0.64 to -0.34, p<0.001). There were no significant differences between central executive and non-executive, perception/attention and short-term memory, tasks. Low (35-60mmHg) PaO 2 was the key predictor of cognitive performance (R 2 =0.45, p<0.001) and this was independent of whether the exposure was in hypobaric hypoxic or normobaric hypoxic conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Overexpression of Notch ligand Delta-like-1 by dendritic cells enhances their immunoregulatory capacity and exerts antiallergic effects on Th2-mediated allergic asthma in mice.

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Lee, Chen-Chen; Lin, Chu-Lun; Leu, Sy-Jye; Lee, Yueh-Lun

2018-02-01

Dendritic cells (DCs) are professional antigen-presenting cells, and Notch ligand Delta-like-1 (DLL1) on DCs was implicated in type 1T helper (Th1) differentiation. In this study, we produced genetically engineered bone marrow-derived DCs that expressed DLL1 (DLL1-DCs) by adenoviral transduction. DLL1-DCs exerted a fully mature phenotype, and had positive effects on expression levels of interleukin (IL)-12 and costimulatory molecules. Coculture of allogeneic T cells with ovalbumin (OVA)-pulsed DLL1-DCs enhanced T cell proliferative responses and promoted Th1 cell differentiation. Furthermore, adoptive transfer of OVA-stimulated DLL1-DCs into asthmatic mice alleviated the cardinal features of allergic asthma, including immunoglobulin E (IgE) production, airway hyperresponsiveness (AHR), airway inflammation, and production of Th2-type cytokines. Notably, enhanced levels of the Th1-biased IgG 2a response and interferon (IFN)-γ production were observed in these mice. Taken together, these data indicate that DLL1-DCs promoted Th1 cell development to alter the Th1/Th2 ratio and ameliorate Th2-mediated allergic asthma in mice. Copyright © 2017 Elsevier Inc. All rights reserved.

Endogenous markers of tumor hypoxia. Predictors of clinical radiation resistance?

International Nuclear Information System (INIS)

Vordermark, D.; Brown, J.M.

2003-01-01

Background: Eppendorf electrode measurements of tumor oxygenation have defined an adverse effect of tumor hypoxia on prognosis after radiotherapy and other treatment modalities, in particular in head and neck and cervix carcinomas as well as soft tissue sarcomas. Recently, the immunohistochemical detection of proteins involved in the ''hypoxic response'' of tumor cells has been discussed as a method to estimate hypoxia in clinical tumor specimens. Material and Methods: This review focuses on clinical and experimental data, regarding prognostic impact and comparability with other methods of hypoxia detection, for three proteins suggested as endogenous markers of tumor hypoxia: hypoxia-inducible factor-1α (HIF-1α), carbonic anhydrase 9 (CA 9), and glucose transporter 1 (GLUT1). Results: None of the three potential hypoxia markers is exclusively hypoxia-specific, and in each case protein can be detected under normoxic conditions in vitro. HIF-1α responds rapidly to hypoxia but also to reoxygenation, making this marker quite unstable in the context of clinical sample collection. The perinecrotic labeling pattern typical of chronic hypoxia and a reasonable agreement with injectable hypoxia markers such as pimonidazole have most consistently been described for CA 9. All three markers showed correlation with Eppendorf electrode measurements of tumor oxygenation in carcinoma of the cervix. In nine of 13 reports, among them all three that refer to curative radiotherapy for head and neck cancer, HIF-1α overexpression was associated with poor outcome. CA 9 was an adverse prognostic factor in cervix, head and neck and lung cancer, but not in two other head and neck cancer reports. GLUT1 predicted for poor survival in colorectal, cervix and lung cancer. Conclusion: Endogenous markers have the potential to indicate therapeutically relevant levels of hypoxia within tumors. Clinical trials assessing a marker's ability to predict a benefit from specific hypoxia

Endogenous markers of tumor hypoxia. Predictors of clinical radiation resistance?

Energy Technology Data Exchange (ETDEWEB)

Vordermark, D. [Dept. of Radiation Oncology, Univ. of Wuerzburg (Germany); Dept. of Radiation Oncology, Stanford Univ. School of Medicine, Stanford, CA (United States); Brown, J.M. [Dept. of Radiation Oncology, Stanford Univ. School of Medicine, Stanford, CA (United States)

2003-12-01

Background: Eppendorf electrode measurements of tumor oxygenation have defined an adverse effect of tumor hypoxia on prognosis after radiotherapy and other treatment modalities, in particular in head and neck and cervix carcinomas as well as soft tissue sarcomas. Recently, the immunohistochemical detection of proteins involved in the ''hypoxic response'' of tumor cells has been discussed as a method to estimate hypoxia in clinical tumor specimens. Material and Methods: This review focuses on clinical and experimental data, regarding prognostic impact and comparability with other methods of hypoxia detection, for three proteins suggested as endogenous markers of tumor hypoxia: hypoxia-inducible factor-1{alpha} (HIF-1{alpha}), carbonic anhydrase 9 (CA 9), and glucose transporter 1 (GLUT1). Results: None of the three potential hypoxia markers is exclusively hypoxia-specific, and in each case protein can be detected under normoxic conditions in vitro. HIF-1{alpha} responds rapidly to hypoxia but also to reoxygenation, making this marker quite unstable in the context of clinical sample collection. The perinecrotic labeling pattern typical of chronic hypoxia and a reasonable agreement with injectable hypoxia markers such as pimonidazole have most consistently been described for CA 9. All three markers showed correlation with Eppendorf electrode measurements of tumor oxygenation in carcinoma of the cervix. In nine of 13 reports, among them all three that refer to curative radiotherapy for head and neck cancer, HIF-1{alpha} overexpression was associated with poor outcome. CA 9 was an adverse prognostic factor in cervix, head and neck and lung cancer, but not in two other head and neck cancer reports. GLUT1 predicted for poor survival in colorectal, cervix and lung cancer. Conclusion: Endogenous markers have the potential to indicate therapeutically relevant levels of hypoxia within tumors. Clinical trials assessing a marker's ability to predict a

[Effects of hypoxia inducible factor-1α on P311 and its influence on the migration of murine epidermal stem cells].

Science.gov (United States)

Xu, Z D; Li, H S; Wang, S; He, W F; Wu, J; Luo, G X

2017-05-20

Objective: To explore the effects of hypoxia inducible factor-1α (HIF-1α) on P311 and its influence on the migration of murine epidermal stem cells (ESCs) under hypoxia in vitro. Methods: Two kinds of murine ESCs were isolated and obtained from 15 neonatal wild-type C57BL/6J mice and 5 congeneric source P311 gene knock-out mice, respectively. The first passage of cells were used in the following experiments after morphologic observation and detection of expression of cell surface markers CD71 and CD49f with flow cytometer. (1) After cell scratch assay, according to the random number table (the same dividing method below), ESCs of P311 gene knock-out mice were divided into normoxia group (cells were cultured with complete medium in normoxic carbon dioxide incubator, and the subsequent normoxic treatments were the same) and hypoxia group (cells were cultured in hypoxic carbon dioxide incubator containing 1% oxygen, and the subsequent hypoxic treatments were the same), with 12 inserts in each group. ESCs of wild-type mice were divided into normoxia group, pure hypoxia group, dimethyl sulfoxide (DMSO) control group (2 μL DMSO solvent was added for 1 h of normoxia treatment before hypoxia treatment), HIF-1α inhibitor group (cells were treated with 11 μmol/L HIF-1 inhibitor of 2 μL under normoxia condition for 1 h before hypoxia treatment), HIF-1α stabilizer group (the cells were treated with 2 μmol/L FG-4592 of 2 μL under normoxia condition for 1 h before hypoxia treatment), with 12 inserts in each group. Three inserts of each time point in each group were adopted respectively to measure the residual width of scratch under inverted phase contrast microscope at post scratch hour (PSH) 0 (immediately), 12, 24, and 48. (2) After hypoxia treatment, the protein level of HIF-1α in ESCs of wild-type mice was detected by Western blotting at post hypoxia hour (PHH) 0, 12, 24, and 48. (3) ESCs of wild-type mice were divided into pure hypoxia group, DMSO control group

Senescence and quiescence in adipose-derived stromal cells: Effects of human platelet lysate, fetal bovine serum and hypoxia.

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Søndergaard, Rebekka Harary; Follin, Bjarke; Lund, Lisbeth Drozd; Juhl, Morten; Ekblond, Annette; Kastrup, Jens; Haack-Sørensen, Mandana

2017-01-01

Adipose-derived stromal cells (ASCs) are attractive sources for cell-based therapies. The hypoxic niche of ASCs in vivo implies that cells will benefit from hypoxia during in vitro expansion. Human platelet lysate (hPL) enhances ASC proliferation rates, compared with fetal bovine serum (FBS) at normoxia. However, the low proliferation rates of FBS-expanded ASCs could be signs of senescence or quiescence. We aimed to determine the effects of hypoxia and hPL on the expansion of ASCs and whether FBS-expanded ASCs are senescent or quiescent. ASCs expanded in FBS or hPL at normoxia or hypoxia until passage 7 (P7), or in FBS until P5 followed by culture in hPL until P7, were evaluated by proliferation rates, cell cycle analyses, gene expression and β-galactosidase activity. hPL at normoxia and hypoxia enhanced proliferation rates and expression of cyclins, and decreased G0/G1 fractions and expression of p21 and p27, compared with FBS. The shift from FBS to hPL enhanced cyclin levels, decreased p21 and p27 levels and tended to decrease G0/G1 fractions. Hypoxia does not add to the effect of hPL during ASC expansion with regard to proliferation, cell cycle regulation and expression of cyclins, p21 and p27. hPL rejuvenates FBS-expanded ASCs with regard to cell cycle regulation and expression of cyclins, p21 and p27. This indicates a reversible arrest. Therefore, we conclude that ASCs expanded until P7 are not senescent regardless of culture conditions. Copyright © 2017 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

[Electrophysiological study on rat conduit pulmonary artery smooth muscle cells under normoxia and acute hypoxia].

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Hu, Ying; Zou, Fei; Cai, Chun-Qing; Wu, Hang-Yu; Yun, Hai-Xia; Chen, Yun-Tian; Jin, Guo-En; Ge, Ri-Li

2006-10-25

The present study was designed to investigate the electrophysiological characteristics of rat conduit pulmonary artery smooth muscle cells (PASMCs) and the response to acute hypoxia. PASMCs of the 1st to 2nd order branches in the conduit pulmonary arteries were obtained by enzymatic isolation. The PASMCs were divided into acute hypoxia preconditioned group and normoxia group. Hypoxia solutions were achieved by bubbling with 5% CO2 plus 95% N2 for at least 30 min before cell perfusion. Potassium currents were compared between these two groups using whole-cell patch clamp technique. The total outward current of PASMCs was measured under normoxia condition when iBTX [specific blocking agent of large conductance Ca-activated K(+) (BK(Ca)) channel] and 4-AP [specific blocking agent of delayed rectifier K(+) (K(DR)) channel] were added consequently into bath solution. PASMCs were classified into three types according to their size, shape and electrophysiological characteristics. Type I cells are the smallest with spindle shape, smooth surface and discrete perinuclear bulge. Type II cells show the biggest size with banana-like appearance. Type III cells have the similar size with type I, and present intermediary shape between type I and type II. iBTX had little effect on the total outward current in type I cells, while 4-AP almost completely blocked it. Most of the total outward current in type II cells was inhibited by iBTX, and the remaining was sensitive to 4-AP. In type III cells, the total outward current was sensitive to both iBTX and 4-AP. Acute hypoxia reduced the current in all three types of cells: (1614.8+/-62.5) pA to (892.4+/-33.6) pA for type I cells (Ppotassium current and improves the E(m) in PASMCs. These effects may be involved in the modulation of constriction/relaxation of conduit artery under acute hypoxia. Different distribution of K(DR) and BK(Ca) channels in these three types of PASMCs might account for their different constriction

Hypoxia: Exposure Time Until Significant Performance Effects

Science.gov (United States)

2016-03-07

three alcoholic beverages per day (on average), or were taking any prescription medication (besides oral contraceptives). Likewise, those who were...or tested positively for pregnancy were disqualified from the study, as the risks of hypoxia to a human fetus are currently unknown. Also, those...that could impact inclusion in the study. After the questionnaire, all female participants provided a urine sample for pregnancy testing. Participants

Exercise performed at hypoxia influences mood state and anxiety symptoms

Directory of Open Access Journals (Sweden)

Jorge Fernando Tavares de Souza

2015-06-01

Full Text Available During hypoxia conditions, psychological states can be worsened. However, little information is available regarding the effect of physical exercise performed in hypoxia conditions on mood state and anxiety symptoms. The aim of the present study was to elucidate the acute effect of moderate physical exercise performed at hypoxia on mood states and anxiety symptoms in healthy young subjects. Ten volunteers were subjected to the following conditions: a normoxic condition (NC and a hypoxic condition (HC. They performed 45 min of physical exercise. Their anxiety symptoms and mood states were evaluated at the initial time point as well as immediately following and 30 and 60 min after the exercise session. Our results showed a significant increase in post-exercise anxiety symptoms and a significant decrease in mood scores immediately after and 30 min after exercise performed in the HC. Moderate physical activity performed at hypoxia condition increased post-exercise anxiety and worsened mood state.

Preclinical evidence of rapid-onset antidepressant-like effect in Radix Polygalae extract.

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Im-Joon Shin

Full Text Available Radix Polygalae (the root of Polygala tenuifolia is a herb widely used in traditional Asian medicine that is thought to exert a variety of neuropsychiatric effects. Radix Polygalae extract can protect against N-methyl D-aspartate (NMDA neurotoxicity and induce brain-derived neurotrophic factor (BDNF expression, suggesting modulatory roles at glutamatergic synapses and possible antidepressant action. In accordance with this hypothesis, Radix Polygalae extract demonstrated antidepressant-like effects in 8-week-old male C57Bl/6 mice by decreasing behavioral despair in the forced swim and tail suspension tasks and increasing hedonic-like behavior in the female urine sniffing test 30 minutes after a single oral administration of 0.1 mg/kg. Reduced latency to acquire a food pellet in the novely suppressed feeding paradigm, without change in anxiety-like behaviors suggested a rapid-onset nature of the antidepressant-like effect. In addition, it decreased the number of failed escapes in the learned helplessness paradigm after two oral administrations 24 hours and 30 minutes before the first test. Finally, it reversed anhedonia as measured by saccharin preference in mice exposed to the chronic stress model after two administrations of 0.1 mg/kg, in contrast to the repeated administration generally needed for similar effect by monoamergic antidepressants. Immobility reduction in tail suspension task was blocked by the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA receptor antagonist NBQX, a pattern previously demonstrated by ketamine and other ketamine-like rapid-onset antidepressants. Also similarly to ketamine, Radix Polygalae appeared to acutely decrease phosphorylation of GluR1 serine-845 in the hippocampus while leaving the phosphorylation of hippocampal mTOR serine 2448 unchanged. These findings serve as preclinical evidence that Radix Polygalae extract exerts rapid-onset antidepressant effects by modulating glutamatergic synapses in

Hypoxia-mimetic agents inhibit proliferation and alter the morphology of human umbilical cord-derived mesenchymal stem cells

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Zeng Hui-Lan

2011-08-01

Full Text Available Abstract Background The therapeutic efficacy of human mesenchymal stem cells (hMSCs for the treatment of hypoxic-ischemic diseases is closely related to level of hypoxia in the damaged tissues. To elucidate the potential therapeutic applications and limitations of hMSCs derived from human umbilical cords, the effects of hypoxia on the morphology and proliferation of hMSCs were analyzed. Results After treatment with DFO and CoCl2, hMSCs were elongated, and adjacent cells were no longer in close contact. In addition, vacuole-like structures were observed within the cytoplasm; the rough endoplasmic reticulum expanded, and expanded ridges were observed in mitochondria. In addition, DFO and CoCl2 treatments for 48 h significantly inhibited hMSCs proliferation in a concentration-dependent manner (P Conclusions The hypoxia-mimetic agents, DFO and CoCl2, alter umbilical cord-derived hMSCs morphology and inhibit their proliferation through influencing the cell cycle.

Protective effects of angiopoietin-like 4 on the blood-brain barrier in acute ischemic stroke treated with thrombolysis in mice.

Science.gov (United States)

Zhang, Bin; Xu, Xiaofeng; Chu, Xiuli; Yu, Xiaoyang; Zhao, Yuwu

2017-04-03

Given the risk of blood-brain barrier damage (BBB) caused by ischemic and tissue plasminogen activator thrombolysis, the preservation of vascular integrity is important. Angiopoietin-like 4 (ANGPTL4), a protein secreted in hypoxia, is involved in the regulation of vascular permeability. We hypothesized that Angptl4 might exert a protective effect in thrombolysis through stabilizing blood-brain barrier and inhibit hyper-permeability. We investigated the role of Angptl4 in stroke using a transient focal cerebral ischemia mouse model. The treated mice were administered Angptl4 1h after the ischemic event upon reperfusion. Our results showed that Angptl4 combined with thrombolysis greatly reduced the infarct volume and consequent neurological deficit. Western blot analyses and gelatin zymography revealed that Angptl4 protected the integrity of the endothelium damaged by thrombolysis. Angptl4 inhibited the up-regulation of vascular endothelial growth factor (VEGF) in the vascular endothelium after stroke, which was suppressed by counteracting VEGFR signaling and diminishing downstream Src signaling, and led to the increased stability of junctions and improved endothelial cell barrier integrity. These findings demonstrated that Angptl4 protects the permeability of the BBB damaged by ischemic and thrombolysis. Suggested that Angptl4 might be a promising target molecule in therapies for vasoprotection after thrombolysis treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

Detrimental effects of hypoxia-specific expression of uracil DNA glycosylase (Ung) in Mycobacterium smegmatis.

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Kurthkoti, Krishna; Varshney, Umesh

2010-12-01

Mycobacterium tuberculosis is known to reside latently in a significant fraction of the human population. Although the bacterium possesses an aerobic mode of metabolism, it adapts to persistence under hypoxic conditions such as those encountered in granulomas. While in mammalian systems hypoxia is a recognized DNA-damaging stress, aspects of DNA repair in mycobacteria under such conditions have not been studied. We subjected Mycobacterium smegmatis, a model organism, to the Wayne's protocol of hypoxia. Analysis of the mRNA of a key DNA repair enzyme, uracil DNA glycosylase (Ung), by real-time reverse transcriptase PCR (RT-PCR) revealed its downregulation during hypoxia. However, within an hour of recovery of the culture under normal oxygen levels, the Ung mRNA was restored. Analysis of Ung by immunoblotting and enzyme assays supported the RNA analysis results. To understand its physiological significance, we misexpressed Ung in M. smegmatis by using a hypoxia-responsive promoter of narK2 from M. tuberculosis. Although the misexpression of Ung during hypoxia decreased C-to-T mutations, it compromised bacterial survival upon recovery at normal oxygen levels. RT-PCR analysis of other base excision repair gene transcripts (UdgB and Fpg) suggested that these DNA repair functions also share with Ung the phenomenon of downregulation during hypoxia and recovery with return to normal oxygen conditions. We discuss the potential utility of this phenomenon in developing attenuated strains of mycobacteria.

Hypoxia triggers high-altitude headache with migraine features: A prospective trial.

Science.gov (United States)

Broessner, Gregor; Rohregger, Johanna; Wille, Maria; Lackner, Peter; Ndayisaba, Jean-Pierre; Burtscher, Martin

2016-07-01

Given the high prevalence and clinical impact of high-altitude headache (HAH), a better understanding of risk factors and headache characteristics may give new insights into the understanding of hypoxia being a trigger for HAH or even migraine attacks. In this prospective trial, we simulated high altitude (4500 m) by controlled normobaric hypoxia (FiO2 = 12.6%) to investigate acute mountain sickness (AMS) and headache characteristics. Clinical symptoms of AMS according to the Lake Louise Scoring system (LLS) were recorded before and after six and 12 hours in hypoxia. O2 saturation was measured using pulse oximetry at the respective time points. History of primary headache, especially episodic or chronic migraine, was a strict exclusion criterion. In total 77 volunteers (43 (55.8%) males, 34 (44.2%) females) were enrolled in this study. Sixty-three (81.18%) and 40 (71.4%) participants developed headache at six or 12 hours, respectively, with height and SpO2 being significantly different between headache groups at six hours (p headache development (p headache according to the International Classification of Headache Disorders (ICHD-3 beta) in n = 5 (8%) or n = 6 (15%), at six and 12 hours, respectively. Normobaric hypoxia is a trigger for HAH and migraine-like headache attacks even in healthy volunteers without any history of migraine. Our study confirms the pivotal role of hypoxia in the development of AMS and beyond that suggests hypoxia may be involved in migraine pathophysiology. © International Headache Society 2015.

Hypoxia inhibits colonic ion transport via activation of AMP kinase.

LENUS (Irish Health Repository)

Collins, Danielle

2012-02-01

BACKGROUND AND AIMS: Mucosal hypoxia is a common endpoint for many pathological processes including ischemic colitis, colonic obstruction and anastomotic failure. Previous studies suggest that hypoxia modulates colonic mucosal function through inhibition of chloride secretion. However, the molecular mechanisms underlying this observation are poorly understood. AMP-activated protein kinase (AMPK) is a metabolic energy regulator found in a wide variety of cells and has been linked to cystic fibrosis transmembrane conductance regulator (CFTR) mediated chloride secretion in several different tissues. We hypothesized that AMPK mediates many of the acute effects of hypoxia on human and rat colonic electrolyte transport. METHODS: The fluorescent chloride indicator dye N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide was used to measure changes in intracellular chloride concentrations in isolated single rat colonic crypts. Ussing chamber experiments in human colonic mucosa were conducted to evaluate net epithelial ion transport. RESULTS: This study demonstrates that acute hypoxia inhibits electrogenic chloride secretion via AMPK mediated inhibition of CFTR. Pre-treatment of tissues with the AMPK inhibitor 6-[4-(2-piperidin-1-yl-ethoxy)-phenyl)]-3-pyridin-4-yl-pyyrazolo [1,5-a] pyrimidine (compound C) in part reversed the effects of acute hypoxia on chloride secretion. CONCLUSION: We therefore suggest that AMPK is a key component of the adaptive cellular response to mucosal hypoxia in the colon. Furthermore, AMPK may represent a potential therapeutic target in diseased states or in prevention of ischemic intestinal injury.

Effects on Task Performance and Psychophysiological Measures of Performance During Normobaric Hypoxia Exposure

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Stephens, Chad; Kennedy, Kellie; Napoli, Nicholas; Demas, Matthew; Barnes, Laura; Crook, Brenda; Williams, Ralph; Last, Mary Carolyn; Schutte, Paul

2017-01-01

Human-autonomous systems have the potential to mitigate pilot cognitive impairment and improve aviation safety. A research team at NASA Langley conducted an experiment to study the impact of mild normobaric hypoxia induction on aircraft pilot performance and psychophysiological state. A within-subjects design involved non-hypoxic and hypoxic exposures while performing three 10-minute tasks. Results indicated the effect of 15,000 feet simulated altitude did not induce significant performance decrement but did produce increase in perceived workload. Analyses of psychophysiological responses evince the potential of biomarkers for hypoxia onset. This study represents on-going work at NASA intending to add to the current knowledge of psychophysiologically-based input to automation to increase aviation safety. Analyses involving coupling across physiological systems and wavelet transforms of cortical activity revealed patterns that can discern between the simulated altitude conditions. Specifically, multivariate entropy of ECG/Respiration components were found to be significant predictors (pTask performance was not appreciably impacted by the effect of 15,000 feet simulated altitude. Analyses of psychophysiological responses evince the potential of biomarkers for mild hypoxia onset.The potential for identifying shifts in underlying cortical and physiological systems could serve as a means to identify the onset of deteriorated cognitive state. Enabling such assessment in future flightdecks could permit increasingly autonomous systems-supported operations. Augmenting human operator through assessment of cognitive impairment has the potential to further improve operator performance and mitigate human error in safety critical contexts. This study represents ongoing work at NASA intending to add to the current knowledge of psychophysiologically-based input to automation to increase aviation safety.

Hydrocortisone Infusion Exerts Dose- and Sex-Dependent Effects on Attention to Emotional Stimuli

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Breitberg, Alaina; Drevets, Wayne C.; Wood, Suzanne E.; Mah, Linda; Schulkin, Jay; Sahakian, Barbara J.; Erickson, Kristine

2013-01-01

Glucocorticoid administration has been shown to exert complex effects on cognitive and emotional processing. In the current study we investigated the effects of glucocorticoid administration on attention towards emotional words, using an Affective Go/No-go task on which healthy humans have shown an attentional bias towards positive as compared to…

Effects of acute intermittent hypoxia on glucose metabolism in awake healthy volunteers

OpenAIRE

Louis, Mariam; Punjabi, Naresh M.

2009-01-01

Accumulating evidence suggests that obstructive sleep apnea is associated with alterations in glucose metabolism. Although the pathophysiology of metabolic dysfunction in obstructive sleep apnea is not well understood, studies of murine models indicate that intermittent hypoxemia has an important contribution. However, corroborating data on the metabolic effects of intermittent hypoxia on glucose metabolism in humans are not available. Thus the primary aim of this study was to characterize th...

Defining the Focus of Attention: Effects of Attention on Perceived Exertion and Fatigue.

Directory of Open Access Journals (Sweden)

Keith eLohse

2011-11-01

Full Text Available This manuscript presents two experiments designed to explore the effects of attention on perceived exertion and time to failure in a fatiguing athletic task. There were two major motivating factors for these experiments. First, there are few studies evaluating attentional focus effects in endurance tasks and, second, there is a lack of integration between studies of attentional focus as external/internal (e.g., Wulf, 2007 compared to associative/dissociative (e.g., Stevenson & Biddle, 1998. In Experiment 1, we used a fatiguing wall-sit posture (essentially a complex, isometric task to compare two different types of external attention with an internal focus on the position of the legs. An external focus (regardless of type increased the time taken to failure and reduced perceived exertion. In Experiment 2, we manipulated subjects’ expectancy of fatigue to test the interaction of attention and expectancy (both top-down factors in this highly fatiguing task. Previous theories of attention during endurance tasks have suggested that as fatigue/pain increase, bottom-up factors begin to dominate subjects’ attention. While this may be true, Experiment 2 showed that even in a highly fatiguing task, attentional strategies and expectancies affected the time to failure and perceived exertion.

The effects of levosimendan on brain metabolism during initial recovery from global transient ischaemia/hypoxia

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Roehl Anna B

2012-08-01

Full Text Available Abstract Backround Neuroprotective strategies after cardiopulmonary resuscitation are currently the focus of experimental and clinical research. Levosimendan has been proposed as a promising drug candidate because of its cardioprotective properties, improved haemodynamic effects in vivo and reduced traumatic brain injury in vitro. The effects of levosimendan on brain metabolism during and after ischaemia/hypoxia are unknown. Methods Transient cerebral ischaemia/hypoxia was induced in 30 male Wistar rats by bilateral common carotid artery clamping for 15 min and concomitant ventilation with 6% O2 during general anaesthesia with urethane. After 10 min of global ischaemia/hypoxia, the rats were treated with an i.v. bolus of 24 μg kg-1 levosimendan followed by a continuous infusion of 0.2 μg kg-1 min-1. The changes in the energy-related metabolites lactate, the lactate/pyruvate ratio, glucose and glutamate were monitored by microdialysis. In addition, the effects on global haemodynamics, cerebral perfusion and autoregulation, oedema and expression of proinflammatory genes in the neocortex were assessed. Results Levosimendan reduced blood pressure during initial reperfusion (72 ± 14 vs. 109 ± 2 mmHg, p = 0.03 and delayed flow maximum by 5 minutes (p = 0.002. Whereas no effects on time course of lactate, glucose, pyruvate and glutamate concentrations in the dialysate could be observed, the lactate/pyruvate ratio during initial reperfusion (144 ± 31 vs. 77 ± 8, p = 0.017 and the glutamate release during 90 minutes of reperfusion (75 ± 19 vs. 24 ± 28 μmol·L-1 were higher in the levosimendan group. The increased expression of IL-6, IL-1ß TNFα and ICAM-1, extend of cerebral edema and cerebral autoregulation was not influenced by levosimendan. Conclusion Although levosimendan has neuroprotective actions in vitro and on the spinal cord in vivo and has been shown to cross the blood–brain barrier, the present

Hepcidin: A Critical Regulator Of Iron Metabolism During Hypoxia

Science.gov (United States)

2011-01-01

inducible factor (HIF)/hypoxia response element ( HRE ) system, as well as recent evidence indicating that localized adipose hypoxia due to obesity may...mechanisms by which hypoxia affects hepcidin expression, to include a review of the hypoxia inducible factor (HIF)/hypoxia response element ( HRE ) system, as...a battery of genes are induced by the hypoxia inducible factor (HIF)/hypoxia response element ( HRE ) system. The HIF system senses O2 levels through

Effects of music and video on perceived exertion during high-intensity exercise

Institute of Scientific and Technical Information of China (English)

Enoch C.Chow; Jennifer L.Etnier

2017-01-01

Background:Dissociative attentional stimuli (e.g.,music,video) are effective in decreasing ratings of perceived exertion (RPE) during low-to-moderate intensity exercise,but have inconsistent results during exercise at higher intensity.The purpose of this study was to assess attentional focus and RPE during high-intensity exercise as a function of being exposed to music,video,both (music and video),or a no-treatment control condition.Methods:During the first session,healthy men (n =15) completed a maximal fitness test to determine the workload necessary for high-intensity exercise (operationalized as 125％ ventilatory threshold) to be performed during subsequent sessions.On 4 subsequent days,they completed 20 min of high-intensity exercise in a no-treatment control condition or while listening to music,watching a video,or both.Attentional focus,RPE,heart rate,and distance covered were measured every 4 min during the exercise.Results:Music and video in combination resulted in significantly lower RPE across time (partial η2 =0.36) and the size of the effect increased over time (partial η2 =0.14).Additionally,music and video in combination resulted in a significantly more dissociative focus than the other conditions (partial η2 =0.29).Conclusion:Music and video in combination may result in lower perceived exertion during high-intensity exercise when compared to music or video in isolation.Future research will be necessary to test if reductions in perceived exertion in response to dissociative attentional stimuli have implications for exercise adherence.

Shared Physiological and Molecular Responses in Marine Fish and Invertebrates to Environmental Hypoxia: Potential Biomarkers of Adverse Impacts on Marine Communities

Science.gov (United States)

Thomas, P.; Rahman, S.

2016-02-01

Knowledge of the effects of environmental exposure to hypoxia (dissolved oxygen: reproduction, growth and metabolism in both fish and invertebrates is essential for accurate predictions of its chronic impacts on marine communities. Marked disruption of reproduction and its endocrine control was observed in Atlantic croaker collected from the hypoxic region in the northern Gulf of Mexico. Recent research has shown that growth and its physiological upregulation is also impaired in hypoxia-exposed marine fish. Expression of insulin-like growth factor (IGF) binding protein (IGFBP), which inhibits growth, was increased in croaker livers, whereas plasma levels of IGF, the primary regulator of growth, were decreased in snapper after hypoxia exposure. In addition, hypoxia inducible factor-1 (HIF-1), which regulates changes in metabolism during adaptation to hypoxia, was upregulated in croaker collected from hypoxic environments. Interestingly, similar changes in the expression of IGFBP and HIF-1 have been found in marine crustaceans after hypoxia exposure, suggesting these responses to hypoxia are common to marine fish and invertebrates. Preliminary field studies indicate that hypoxia exposure also causes epigenetic modifications, including increases in global DNA methylation, and that these epigenetic changes can influence reproduction and growth in croaker. Epigenetic modifications can be passed to offspring and persist in future generations no longer exposed to an environmental stressor further aggravating its long-term adverse impacts on population abundance and delaying recovery. The growing availability of complete invertebrate genomes and high-throughput DNA sequencing indicates similar epigenetic studies can now be conducted with marine invertebrates. Collectively, the results indicate that environmental hypoxia exposure disrupts major physiological functions in fish and invertebrates critical for maintenance of their populations.

Effects of caffeine on neuromuscular fatigue and performance during high-intensity cycling exercise in moderate hypoxia.

Science.gov (United States)

Smirmaul, Bruno P C; de Moraes, Antonio Carlos; Angius, Luca; Marcora, Samuele M

2017-01-01

To investigate the effects of caffeine on performance, neuromuscular fatigue and perception of effort during high-intensity cycling exercise in moderate hypoxia. Seven adult male participants firstly underwent an incremental exercise test on a cycle ergometer in conditions of acute normobaric hypoxia (fraction inspired oxygen = 0.15) to establish peak power output (PPO). In the following two visits, they performed a time to exhaustion test (78 ± 3% PPO) in the same hypoxic conditions after caffeine ingestion (4 mg kg -1 ) and one after placebo ingestion in a double-blind, randomized, counterbalanced cross-over design. Caffeine significantly improved time to exhaustion by 12%. A significant decrease in subjective fatigue was found after caffeine consumption. Perception of effort and surface electromyographic signal amplitude of the vastus lateralis were lower and heart rate was higher in the caffeine condition when compared to placebo. However, caffeine did not reduce the peripheral and central fatigue induced by high-intensity cycling exercise in moderate hypoxia. The caffeine-induced improvement in time to exhaustion during high-intensity cycling exercise in moderate hypoxia seems to be mediated by a reduction in perception of effort, which occurs despite no reduction in neuromuscular fatigue.

Oxidative stress and apoptosis after acute respiratory hypoxia and reoxygenation in rat brain

Directory of Open Access Journals (Sweden)

Debora Coimbra-Costa

2017-08-01

Full Text Available Acute hypoxia increases the formation of reactive oxygen species (ROS in the brain. However, the effect of reoxygenation, unavoidable to achieve full recovery of the hypoxic organ, has not been clearly established. The aim of the present study was to evaluate the effects of exposition to acute severe respiratory hypoxia followed by reoxygenation on the evolution of oxidative stress and apoptosis in the brain. We investigated the effect of in vivo acute severe normobaric hypoxia (rats exposed to 7% O2 for 6 h and reoxygenation in normoxia (21% O2 for 24 h or 48 h on oxidative stress markers, the antioxidant system and apoptosis in the brain. After respiratory hypoxia we found increased levels of HIF-1α expression, lipid peroxidation, protein oxidation and nitric oxide in brain extracts. Antioxidant defence systems such as superoxide dismutase (SOD, reduced glutathione (GSH and glutathione peroxidase (GPx and the reduced/oxidized glutathione (GSH/GSSG ratio were significantly decreased in the brain. After 24 h of reoxygenation, oxidative stress parameters and the anti-oxidant system returned to control values. Regarding the apoptosis parameters, acute hypoxia increased cytochrome c, AIF and caspase 3 activity in the brain. The apoptotic effect is greatest after 24 h of reoxygenation. Immunohistochemistry suggests that CA3 and dentate gyrus in the hippocampus seem more susceptible to hypoxia than the cortex. Severe acute hypoxia increases oxidative damage, which in turn could activate apoptotic mechanisms. Our work is the first to demonstrate that after 24 h of reoxygenation oxidative stress is attenuated, while apoptosis is maintained mainly in the hippocampus, which may, in fact, be the cause of impaired brain function. Keywords: Antioxidants, Apoptosis, Normobaric hypoxia, Oxidative stress, Reoxygenation

Is decision making in hypoxia affected by pre-acclimatisation? A randomized controlled trial.

Science.gov (United States)

Niedermeier, Martin; Weisleitner, Andreas; Lamm, Claus; Ledochowski, Larissa; Frühauf, Anika; Wille, Maria; Burtscher, Martin; Kopp, Martin

2017-05-01

Decision making is impaired in hypoxic environments, which may have serious or even lethal consequences for mountaineers. An acclimatisation period prior to high altitude exposures may help to overcome adverse effects of hypoxia. Thus, we investigated possible effects of short-term pre-acclimatisation on decision making in hypoxia. In a randomized controlled study design, 52 healthy participants were allocated to a hypoxia group (HG: short-term pre-acclimatisation by the use of intermittent hypoxia 7×1h at F i O 2 =12.6%, equivalent to 4500m) or a control group (CG: sham pre-acclimatisation 7×1h at F i O 2 =20.9%, equivalent to 600m). The number of risky decisions was assessed using the Game of Dice Task at four time points during a 12-hours stay in hypoxia (F i O 2 =12.6%). 42 (HG: 27, CG: 25) participants completed the study. The number of risky decisions was significantly (p=0.048 as determined by 4×2 ANCOVA) reduced in the hypoxia group compared to the control group, partial η 2 =0.11, when the age-effect on decision making was controlled. Self-reported positive affective valence prior to decision making was negatively related to the number of risky decisions, rdecision making in hypoxia in a positive way and might be considered as a risk-reducing preparation method prior to exposures to hypoxic environments. Positive affective states seem to have a medium-sized protective effect against risky decision making. Copyright © 2017 Elsevier Inc. All rights reserved.

Hypoxia-inducible transcription factor-1α promotes hypoxia-induced A549 apoptosis via a mechanism that involves the glycolysis pathway

International Nuclear Information System (INIS)

Luo, FengMing; Liu, XiaoJing; Yan, NaiHong; Li, ShuangQing; Cao, GuiQun; Cheng, QingYing; Xia, QingJie; Wang, HongJing

2006-01-01

Hypoxia-inducible transcription factor-1α (HIF-1α), which plays an important role in controlling the hypoxia-induced glycolysis pathway, is a 'master' gene in the tissue hypoxia response during tumor development. However, its role in the apoptosis of non-small cell lung cancer remains unknown. Here, we have studied the effects of HIF-1α on apoptosis by modulating HIF-1α gene expression in A549 cells through both siRNA knock-down and over-expression. A549 cells were transfected with a HIF-1α siRNA plasmid or a HIF-1α expression vector. Transfected cells were exposed to a normoxic or hypoxic environment in the presence or absence of 25 mM HEPES and 2-deoxyglucose (2-DG) (5 mM). The expression of three key genes of the glycolysis pathway, glucose transporter type 1(GLUT1), phosphoglycerate kinase 1(PGK1), and hexokinase 1(HK1), were measured using real-time RT-PCR. Glycolysis was monitored by measuring changes of pH and lactate concentration in the culture medium. Apoptosis was detected by TUNEL assay and flow cytometry. Knocking down expression of HIF-1α inhibited the glycolysis pathway, increased the pH of the culture medium, and protected the cells from hypoxia-induced apoptosis. In contrast, over-expression of HIF-1α accelerated glycolysis in A549 cells, decreased the pH of the culture medium, and enhanced hypoxia-induced apoptosis. These effects of HIF-1α on glycolysis, pH of the medium, and apoptosis were reversed by treatment with the glycolytic inhibitor, 2-DG. Apoptosis induced by HIF-1α over-expression was partially inhibited by increasing the buffering capacity of the culture medium by adding HEPES. During hypoxia in A549 cells, HIF-1α promotes activity of the glycolysis pathway and decreases the pH of the culture medium, resulting in increased cellular apoptosis

Examining Effects of Physical Exertion on the Dynamic Visual Acuity Test in Collegiate Athletes.

Science.gov (United States)

Patterson, Jessie N; Murphy, Anna M; Honaker, Julie A

2017-01-01

Acute symptoms of dizziness and/or imbalance commonly experienced in athletes postconcussion are speculated to arise from dysfunction at multiple levels (i.e., inner ear or central vestibular system) to appropriately integrate afferent sensory information. Disruption along any pathway of the balance system can result in symptoms of dizziness, decreased postural control function (vestibulospinal reflex), and reduced vestibulo-ocular reflex function. This may also lead to decreased gaze stability with movements of the head and may account for symptoms of blurred vision or diplopia reported in almost half of athletes sustaining a concussion. Current concussion position statements include measures of postural control to examine changes to the balance system postconcussion. The Balance Error Scoring System (BESS) is a commonly used low-cost postural control measure for concussion assessment. Although this is a widely used measure for documenting balance function on both immediate (sideline) and recovery monitoring, the BESS has been shown to be affected by physical exertion. Therefore, the BESS may not be the most efficient means of examining functional changes to the balance system immediately after head injury. Dynamic Visual Acuity Test (DVAT) has been found to effectively evaluate and monitor changes to the gaze stability system postinjury. Thus, DVAT may be an additional measure in the concussion assessment battery, as well as an alternative for more immediate sideline assessment to help make objective return-to-play decisions. The aim of the study was to determine the effects of physical exertion on a clinical vestibular assessment, the DVAT, in collegiate athletes, as a first step in defining the role of this measure in the concussion assessment battery. Cross-sectional, repeated-measures design. Twenty-eight healthy collegiate athletes (20 males, 8 females; age = 20.25 ± 1.46 yr, range = 18-25 yr) volunteered to participate in the study. Participants were

Hypoxia and bicarbonate could limit the expression of iron acquisition genes in Strategy I plants by affecting ethylene synthesis and signaling in different ways.

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García, María J; García-Mateo, María J; Lucena, Carlos; Romera, Francisco J; Rojas, Carmen L; Alcántara, Esteban; Pérez-Vicente, Rafael

2014-01-01

In a previous work, it was shown that bicarbonate (one of the most important factors causing Fe chlorosis in Strategy I plants) can limit the expression of several genes involved in Fe acquisition. Hypoxia is considered another important factor causing Fe chlorosis, mainly on calcareous soils. However, to date it is not known whether hypoxia aggravates Fe chlorosis by affecting bicarbonate concentration or by specific negative effects on Fe acquisition. Results found in this work show that hypoxia, generated by eliminating the aeration of the nutrient solution, can limit the expression of several Fe acquisition genes in Fe-deficient Arabidopsis, cucumber and pea plants, like the genes for ferric reductases AtFRO2, PsFRO1 and CsFRO1; iron transporters AtIRT1, PsRIT1 and CsIRT1; H(+) -ATPase CsHA1; and transcription factors AtFIT, AtbHLH38, and AtbHLH39. Interestingly, the limitation of the expression of Fe-acquisition genes by hypoxia did not occur in the Arabidopsis ethylene constitutive mutant ctr1, which suggests that the negative effect of hypoxia is related to ethylene, an hormone involved in the upregulation of Fe acquisition genes. As for hypoxia, results obtained by applying bicarbonate to the nutrient solution suggests that ethylene is also involved in its negative effect, since ACC (1-aminocyclopropane-1-carboxylic acid; ethylene precursor) partially reversed the negative effect of bicarbonate on the expression of Fe acquisition genes. Taken together, the results obtained show that hypoxia and bicarbonate could induce Fe chlorosis by limiting the expression of Fe acquisition genes, probably because each factor negatively affects different steps of ethylene synthesis and/or signaling. © 2013 Scandinavian Plant Physiology Society.

Acute hypoxia limits endurance but does not affect muscle contractile properties.

NARCIS (Netherlands)

Degens, H.; Sanchez Horneros, J.M.; Hopman, M.T.E.

2006-01-01

Acute hypoxia causes skeletal muscle dysfunction in vitro, but little is known about its effect on muscle function in vivo. In 10 healthy male subjects, isometric contractile properties and fatigue resistance of the quadriceps muscle were determined during normoxia and hypoxia using electrically

Toll-like Receptor 3 Regulates Angiogenesis and Apoptosis in Prostate Cancer Cell Lines through Hypoxia-Inducible Factor 1α

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Alessio Paone

2010-07-01

Full Text Available Toll-like receptors (TLRs recognize microbial/viral-derived components that trigger innate immune response and conflicting data implicate TLR agonists in cancer, either as protumor or antitumor agents. We previously demonstrated that TLR3 activation mediated by its agonist poly(I:C induces antitumor signaling, leading to apoptosis of prostate cancer cells LNCaP and PC3 with much more efficiency in the former than in the second more aggressive line. The transcription factor hypoxia-induciblefactor 1 (HIF-1regulates several cellular processes, includingapoptosis, in response to hypoxia and to other stimuli also in normoxic conditions. Here we describe a novel protumor machinery triggered by TLR3 activation in PC3 cells consisting of increased expression of the specific 1.3 isoform of HIF-1α and nuclear accumulation of HIF-1 complex in normoxia, resulting in reduced apoptosis and in secretion of functional vascular endothelial growth factor (VEGF. Moreover, we report that, in the less aggressive LNCaP cells, TLR3 activation fails to induce nuclear accumulation of HIF-1α. However, the transfection of 1.3 isoform of hif-1α in LNCaP cells allows poly(I:CI-induced HIF-1 activation, resulting in apoptosis protection and VEGF secretion. Altogether, our findings demonstrate that differences in the basal level of HIF-1α expression in different prostate cancer cell lines underlie their differential response to TLR3 activation, suggesting a correlation between different stages of malignancy, hypoxic gene expression, and beneficial responsiveness to TLR agonists.

Endurance Exercise in Hypoxia, Hyperoxia and Normoxia: Mitochondrial and Global Adaptations.

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Przyklenk, Axel; Gutmann, Boris; Schiffer, Thorsten; Hollmann, Wildor; Strueder, Heiko K; Bloch, Wilhelm; Mierau, Andreas; Gehlert, Sebastian

2017-07-01

We hypothesized short-term endurance exercise (EN) in hypoxia (HY) to exert decreased mitochondrial adaptation, peak oxygen consumption (VO 2peak ) and peak power output (PPO) compared to EN in normoxia (NOR) and hyperoxia (PER). 11 male subjects performed repeated unipedal cycling EN in HY, PER, and NOR over 4 weeks in a cross-over design. VO 2peak , PPO, rate of perceived exertion (RPE) and blood lactate (Bla) were determined pre- and post-intervention to assess physiological demands and adaptation. Skeletal muscle biopsies were collected to determine molecular mitochondrial signaling and adaptation. Despite reduced exercise intensity (P0.05). Electron transport chain complexes tended to increase in all groups with the highest increase in HY (n.s.). EN-induced mitochondrial adaptability and exercise capacity neither decreased significantly in HY nor increased in PER compared to NOR. Despite decreased exercise intensity, short term EN under HY may not necessarily impair mitochondrial adaptation and exercise capacity while PER does not augment adaptation. HY might strengthen adaptive responses under circumstances when absolute training intensity has to be reduced. © Georg Thieme Verlag KG Stuttgart · New York.

An insert-based enzymatic cell culture system to rapidly and reversibly induce hypoxia: investigations of hypoxia-induced cell damage, protein expression and phosphorylation in neuronal IMR-32 cells

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Ying Huang

2013-11-01

Ischemia-reperfusion injury and tissue hypoxia are of high clinical relevance because they are associated with various pathophysiological conditions such as myocardial infarction and stroke. Nevertheless, the underlying mechanisms causing cell damage are still not fully understood, which is at least partially due to the lack of cell culture systems for the induction of rapid and transient hypoxic conditions. The aim of the study was to establish a model that is suitable for the investigation of cellular and molecular effects associated with transient and long-term hypoxia and to gain insights into hypoxia-mediated mechanisms employing a neuronal culture system. A semipermeable membrane insert system in combination with the hypoxia-inducing enzymes glucose oxidase and catalase was employed to rapidly and reversibly generate hypoxic conditions in the culture medium. Hydrogen peroxide assays, glucose measurements and western blotting were performed to validate the system and to evaluate the effects of the generated hypoxia on neuronal IMR-32 cells. Using the insert-based two-enzyme model, hypoxic conditions were rapidly induced in the culture medium. Glucose concentrations gradually decreased, whereas levels of hydrogen peroxide were not altered. Moreover, a rapid and reversible (onoff generation of hypoxia could be performed by the addition and subsequent removal of the enzyme-containing inserts. Employing neuronal IMR-32 cells, we showed that 3 hours of hypoxia led to morphological signs of cellular damage and significantly increased levels of lactate dehydrogenase (a biochemical marker of cell damage. Hypoxic conditions also increased the amounts of cellular procaspase-3 and catalase as well as phosphorylation of the pro-survival kinase Akt, but not Erk1/2 or STAT5. In summary, we present a novel framework for investigating hypoxia-mediated mechanisms at the cellular level. We claim that the model, the first of its kind, enables researchers to rapidly and

Regulation of mRNA translation influences hypoxia tolerance

International Nuclear Information System (INIS)

Koritzinsky, M.; Wouters, B.G.; Koumenis, C.

2003-01-01

Hypoxia is a heterogenous but common characteristic of human tumours and poor oxygenation is associated with poor prognosis. We believe that the presence of viable hypoxic tumor cells reflects in part an adaptation and tolerance of these cells to oxygen deficiency. Since oxidative phosphorylation is compromized during hypoxia, adaptation may involve both the upregulation of glycolysis as well as downregulation of energy consumption. mRNA translation is one of the most energy costly cellular processes, and we and others have shown that global mRNA translation is rapidly inhibited during hypoxia. However, some mRNAs, including those coding for HIF-1 α and VEGF, remain efficiently translated during hypoxia. Clearly, the mechanisms responsible for the overall inhibition of translation during hypoxia does not compromize the translation of certain hypoxia-induced mRNA species. We therefore hypothesize that the inhibition of mRNA translation serves to promote hypoxia tolerance in two ways: i) through conservation of energy and ii) through differential gene expression involved in hypoxia adaptation. We have recently identified two pathways that are responsible for the global inhibition of translation during hypoxia. The phosphorylation of the eukaryotic initiation factor eIF2 α by the ER resident kinase PERK results in down-regulation of protein synthesis shortly after the onset of hypoxia. In addition, the initiation complex eIF4F is disrupted during long lasting hypoxic conditions. The identification of the molecular pathways responsible for the inhibition of overall translation during hypoxia has rendered it possible to investigate their importance for hypoxia tolerance. We have found that mouse embryo fibroblasts that are knockout for PERK and therefore not able to inhibit protein synthesis efficiently during oxygen deficiency are significantly less tolerant to hypoxia than their wildtype counterparts. We are currently also investigating the functional significance

Design of optimized hypoxia-activated prodrugs using pharmacokinetic/pharmacodynamic modeling

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Annika Bettina Foehrenbacher

2013-12-01

Full Text Available Hypoxia contributes to resistance of tumors to some cytotoxic drugs and to radiotherapy, but can in principle be exploited with hypoxia-activated prodrugs (HAP. HAP in clinical development fall into two broad groups. Class I HAP (like the benzotriazine N-oxides tirapazamine and SN30000, are activated under relatively mild hypoxia. In contrast, Class II HAP (such as the nitro compounds PR-104A or TH-302 are maximally activated only under extreme hypoxia, but their active metabolites (effectors diffuse to cells at intermediate O2 and thus also eliminate moderately hypoxic cells. Here, we use a spatially resolved pharmacokinetic/pharmacodynamic (SR-PK/PD model to compare these two strategies and to identify the features required in an optimal Class II HAP. The model uses a Green’s function approach to calculate spatial and longitudinal gradients of O2, prodrug and effector concentrations, and resulting killing in a digitized 3D tumor microregion to estimate activity as monotherapy and in combination with radiotherapy. An analogous model for a normal tissue with mild hypoxia and short intervesssel distances (based on a cremaster muscle microvessel network was used to estimate tumor selectivity of cell killing. This showed that Class II HAP offer advantages over Class I including higher tumor selectivity and greater freedom to vary prodrug diffusibility and rate of metabolic activation. The model suggests that the largest gains in class II HAP antitumor activity could be realized by optimizing effector stability and prodrug activation rates. We also use the model to show that diffusion of effector into blood vessels is unlikely to materially increase systemic exposure for realistic tumor burdens and effector clearances. However, we show that the tumor selectivity achievable by hypoxia-dependent prodrug activation alone is limited if dose-limiting normal tissues are even mildly hypoxic

Weakening of the radioprotective action of gas hypoxia with growth of ascitic tumors

Energy Technology Data Exchange (ETDEWEB)

Aytmagambetova, B Z; Shmakova, N L; Fadeyeva, T A

1975-06-27

It was shown previously that moderate hypoxia induced by breathing oxygen-poor air (5 percent O/sub 2/) reduces the lethal effect of the total irradiation of mice, while with local irradiation of tumors reduction of tumor growth rate is even more marked in hypoxia-protected animals than with irradiation of mice in normal air. This suggests the possible therapeutic application of hypoxia. It was found that acute gas hypoxia strongly retards radiation damage to bone marrow, both qualitatively (type of cells affected) and quantitatively. In addition, a definite weakening of the protective effect of hypoxia was observed, this being proportional to increase in tumor size. Planned future tests involving direct dynamic measurement of oxygen stress as a function of amount of ascites are expected to supply further information on reduction of radiosensitivity of normal tissues and on the selective intensification of tumor regression. Graphic data accompany the paper. (JPRS)

Cold shock protein YB-1 is involved in hypoxia-dependent gene transcription

International Nuclear Information System (INIS)

Rauen, Thomas; Frye, Bjoern C.; Wang, Jialin; Raffetseder, Ute; Alidousty, Christina; En-Nia, Abdelaziz; Floege, Jürgen; Mertens, Peter R.

2016-01-01

Hypoxia-dependent gene regulation is largely orchestrated by hypoxia-inducible factors (HIFs), which associate with defined nucleotide sequences of hypoxia-responsive elements (HREs). Comparison of the regulatory HRE within the 3′ enhancer of the human erythropoietin (EPO) gene with known binding motifs for cold shock protein Y-box (YB) protein-1 yielded strong similarities within the Y-box element and 3′ adjacent sequences. DNA binding assays confirmed YB-1 binding to both, single- and double-stranded HRE templates. Under hypoxia, we observed nuclear shuttling of YB-1 and co-immunoprecipitation assays demonstrated that YB-1 and HIF-1α physically interact with each other. Cellular YB-1 depletion using siRNA significantly induced hypoxia-dependent EPO production at both, promoter and mRNA level. Vice versa, overexpressed YB-1 significantly reduced EPO-HRE-dependent gene transcription, whereas this effect was minor under normoxia. HIF-1α overexpression induced hypoxia-dependent gene transcription through the same element and accordingly, co-expression with YB-1 reduced HIF-1α-mediated EPO induction under hypoxic conditions. Taken together, we identified YB-1 as a novel binding factor for HREs that participates in fine-tuning of the hypoxia transcriptome. - Highlights: • Hypoxia drives nuclear translocation of cold shock protein YB-1. • YB-1 physically interacts with hypoxia-inducible factor (HIF)-1α. • YB-1 binds to the hypoxia-responsive element (HRE) within the erythropoietin (EPO) 3′ enhancer. • YB-1 trans-regulates transcription of hypoxia-dependent genes such as EPO and VEGF.

Ursodeoxycholic acid protects cardiomyocytes against cobalt chloride induced hypoxia by regulating transcriptional mediator of cells stress hypoxia inducible factor 1α and p53 protein.

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Mohamed, Anis Syamimi; Hanafi, Noorul Izzati; Sheikh Abdul Kadir, Siti Hamimah; Md Noor, Julina; Abdul Hamid Hasani, Narimah; Ab Rahim, Sharaniza; Siran, Rosfaiizah

2017-10-01

In hepatocytes, ursodeoxycholic acid (UDCA) activates cell signalling pathways such as p53, intracellular calcium ([Ca 2+ ] i ), and sphingosine-1-phosphate (S1P)-receptor via Gα i -coupled-receptor. Recently, UDCA has been shown to protect the heart against hypoxia-reoxygenation injury. However, it is not clear whether UDCA cardioprotection against hypoxia acts through a transcriptional mediator of cells stress, HIF-1α and p53. Therefore, in here, we aimed to investigate whether UDCA could protect cardiomyocytes (CMs) against hypoxia by regulating expression of HIF-1α, p53, [Ca 2+ ] i , and S1P-Gα i -coupled-receptor. Cardiomyocytes were isolated from newborn rats (0-2 days), and hypoxia was induced by using cobalt chloride (CoCl 2 ). Cardiomyocytes were treated with UDCA and cotreated with either FTY720 (S1P-receptor agonist) or pertussis toxin (PTX; Gα i inhibitor). Cells were subjected for proliferation assay, beating frequency, QuantiGene Plex assay, western blot, immunofluorescence, and calcium imaging. Our findings showed that UDCA counteracted the effects of CoCl 2 on cell viability, beating frequency, HIF-1α, and p53 protein expression. We found that these cardioprotection effects of UDCA were similar to FTY720, S1P agonist. Furthermore, we observed that UDCA protects CMs against CoCl 2 -induced [Ca 2+ ] i dynamic alteration. Pharmacological inhibition of the Gα i -sensitive receptor did not abolish the cardioprotection of UDCA against CoCl 2 detrimental effects, except for cell viability and [Ca 2+ ] i . Pertussis toxin is partially effective in inhibiting UDCA protection against CoCl 2 effects on CM cell viability. Interestingly, PTX fully inhibits UDCA cardioprotection on CoCl 2 -induced [Ca 2+ ] i dynamic changes. We conclude that UDCA cardioprotection against CoCl 2 -induced hypoxia is similar to FTY720, and its actions are not fully mediated by the Gα i -coupled protein sensitive pathways. Ursodeoxycholic acid is the most hydrophilic bile

Impact of Hypoxia on the Metastatic Potential of Human Prostate Cancer Cells

International Nuclear Information System (INIS)

Dai Yao; Bae, Kyungmi; Siemann, Dietmar W.

2011-01-01

Purpose: Intratumoral hypoxia is known to be associated with radioresistance and metastasis. The present study examined the effect of acute and chronic hypoxia on the metastatic potential of prostate cancer PC-3, DU145, and LNCaP cells. Methods and Materials: Cell proliferation and clonogenicity were tested by MTT assay and colony formation assay, respectively. 'Wound-healing' and Matrigel-based chamber assays were used to monitor cell motility and invasion. Hypoxia-inducible factor 1 alpha (HIF-1α) expression was tested by Western blot, and HIF-1-target gene expression was detected by real-time polymerase chain reaction. Secretion of matrix metalloproteinases (MMPs) was determined by gelatin zymography. Results: When PC-3 cells were exposed to 1% oxygen (hypoxia) for various periods of time, chronic hypoxia (≥24 h) decreased cell proliferation and induced cell death. In contrast, prostate cancer cells exposed to acute hypoxia (≤6 h) displayed increased motility, clonogenic survival, and invasive capacity. At the molecular level, both hypoxia and anoxia transiently stabilized HIF-1α. Exposure to hypoxia also induced the early expression of MMP-2, an invasiveness-related gene. Treatment with the HIF-1 inhibitor YC-1 attenuated the acute hypoxia-induced migration, invasion, and MMP-2 activity. Conclusions: The length of oxygen deprivation strongly affected the functional behavior of all three prostate cancer cell lines. Acute hypoxia in particular was found to promote a more aggressive metastatic phenotype.

Apelin Protects Primary Rat Retinal Pericytes from Chemical Hypoxia-Induced Apoptosis

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Li Chen

2015-01-01

Full Text Available Pericytes are a population of cells that participate in normal vessel architecture and regulate permeability. Apelin, as the endogenous ligand of G protein-coupled receptor APJ, participates in a number of physiological and pathological processes. To date, the effect of apelin on pericyte is not clear. Our study aimed to investigate the potential protection mechanisms of apelin, with regard to primary rat retinal pericytes under hypoxia. Immunofluorescence staining revealed that pericytes colocalized with APJ in the fibrovascular membranes dissected from proliferative diabetic retinopathy patients. In the in vitro studies, we first demonstrated that the expression of apelin/APJ was upregulated in pericytes under hypoxia, and apelin increased pericytes proliferation and migration. Moreover, knockdown of apelin in pericyte was achieved via lentivirus-mediated RNA interference. After the inhibition of apelin, pericytes proliferation was inhibited significantly in hypoxia culture condition. Furthermore, exogenous recombinant apelin effectively prevented hypoxia-induced apoptosis through downregulating active-caspase 3 expression and increasing the ratio of B cell lymphoma-2 (Bcl-2/Bcl-2 associated X protein (Bax in pericytes. These results suggest that apelin suppressed hypoxia-induced pericytes injury, which indicated that apelin could be a potential therapeutic target for retinal angiogenic diseases.

The radiation response of cells recovering after chronic hypoxia

International Nuclear Information System (INIS)

Kwok, T.T.; Sutherland, R.M.

1989-01-01

Experiments were performed to study the influence of hypoxic pretreatment on the radiation response of A431 human squamous carcinoma cells. Reaeration for 10 min after chronic hypoxia (greater than 2 h) was found to enhance the radiosensitivity of A431 cells, and the maximal effect was seen for those cells reaerated after 12 h of hypoxia. The radiosensitivity enhancement for reaerated cells after 12 h of hypoxia was maximized by 5 min after the return to aerobic conditions and reached the control level by 12 h of reaeration. This enhanced radiosensitive state was characterized by a reduced shoulder region and increased slope of the radiation dose-response curve for cells in both the exponential and plateau phases of growth. There was a slight increase in the number of G1 and decrease in the number of S and G2 + M cells for both exponential- and plateau-phase cultures following 12 h hypoxic treatment. Although growth inhibition induced by 12 h of hypoxia was seen for cells in the exponential phase, there was no cell number change in the plateau-phase culture after hypoxia. Plating efficiency (PE) of cells in both growth phases was reduced by 30% after hypoxia. Furthermore, in the exponential-phase culture, the extent of reduction in PE after hypoxia was similar among cells in different phases of the cell cycle. Although S-phase cells in exponentially growing cultures were relatively more resistant to radiation than G1 and G2 + M cells, the cell age-response pattern was the same whether the cells had been aerobic or hypoxic before reaeration and irradiation. Furthermore, the enhancement ratio associated with reaeration after 12 h of hypoxia for these three subpopulations of cells was 1.3. Our results indicate that the increase in radiosensitivity due to reaeration after chronic hypoxia is unlikely to be related to the changes of cell cycle stage and growth phase during hypoxic treatment

The Effect of Perinatal Hypoxia on Red Blood Cell Morphology in Newborns

OpenAIRE

S. A. Perepelitsa; V. A. Sergunova; O. E. Gudkova

2017-01-01

Aim. To study the red blood cell (RBC) morphology in newborn infants with a history of perinatal hypoxia using the atomic-force microscopy. Material and methods. The state of RBC membranes of 10 newborns with a history of perinatal hypoxia was studied. All infants were born with low Apgar scoring; the following resuscitative measures were carried out at birth: tracheal intubation, mechanical ventilation (MV). The study group newborns were transferred from the delivery room to the ICU, where M...

Interactive effects of hypoxia and PCB co-exposure on expression of CYP1A and its potential regulators in Atlantic croaker liver.

Science.gov (United States)

Rahman, Md Saydur; Thomas, Peter

2018-04-01

Although marine and coastal environments which are contaminated with xenobiotic organic compounds often become hypoxic during the summer, the interactive effects of hypoxia and xenobiotic exposure on marine species such as teleost fishes remain poorly understood. The expression and activity of monooxygenase enzyme cytochrome P450-1A (CYP1A) in fishes are upregulated by exposure to polychlorinated biphenyls (PCBs), whereas they are down-regulated during hypoxia exposure. We investigated the interactive effects of hypoxia and PCB co-exposure on hepatic CYP1A expression in Atlantic croaker and on potential regulators of CYP1A. Croaker were exposed to hypoxia (1.7 mg/L dissolved oxygen), 3,3',4,4'-tetrachlorobiphenyl (PCB 77, dose: 2 and 8 µg/g body weight), and Aroclor 1254 (a common PCB mixture, dose: 0.5 and 1 µg/g body weight), alone and in combination for 4 weeks. PCB 77 exposure markedly increased hepatic CYP1A mRNA and protein expression, and ethoxyresorufin-O-deethylase (EROD, an indicator of CYP1A enzyme) activity and increased endothelial nitric oxide synthase (eNOS) protein expression. PCB 77 treatment also increased interleukin-1β (IL-1β, a cytokine) mRNA levels and protein carbonyl (PC, an indicator of reactive oxygen species, ROS) contents. These marked PCB 77- and Aroclor 1254-induced increases in CYP1A mRNA levels and EROD activity were significantly attenuated by co-exposure to hypoxia, whereas the increases in hepatic eNOS protein and IL-1β mRNA expression, and PC contents were augmented by hypoxia co-exposure. The results suggest that biotransformation of organic xenobiotics by CYP1A is reduced in fish during co-exposure to hypoxia and is accompanied by alterations in eNOS, ROS, and IL-1β levels. © 2018 Wiley Periodicals, Inc.

Severe hypoxia induces chemo-resistance in clinical cervical tumors through MVP over-expression.

Science.gov (United States)

Lara, Pedro C; Lloret, Marta; Clavo, Bernardino; Apolinario, Rosa M; Henríquez-Hernández, Luis Alberto; Bordón, Elisa; Fontes, Fausto; Rey, Agustín

2009-08-06

Oxygen molecule modulates tumour response to radiotherapy. Higher radiation doses are required under hypoxic conditions to induce cell death. Hypoxia may inhibit the non-homologous end-joining DNA repair through down regulating Ku70/80 expression. Hypoxia induces drug resistance in clinical tumours, although the mechanism is not clearly elucidated. Vaults are ribonucleoprotein particles with a hollow barrel-like structure composed of three proteins: major vault protein (MVP), vault poly(ADP-ribose) polymerase, and telomerase associated protein-1 and small untranslated RNA. Over-expression of MVP has been associated with chemotherapy resistance. Also, it has been related to poor outcome in patients treated with radiotherapy alone. The aim of the present study was to assess the relation of Major Vault Protein expression and tumor hypoxia in clinical cervical tumors. MVP, p53 and angiogenesis, together with tumor oxygenation, were determined in forty-three consecutive patients suffering from localized cervix carcinoma. High MVP expression was related to severe hypoxia compared to low MVP expressing tumors (p = 0.022). Tumors over-expressing MVP also showed increased angiogenesis (p = 0.003). Besides it, in this study we show for the first time that severe tumor hypoxia is associated with high MVP expression in clinical cervical tumors. Up-regulation of MVP by hypoxia is of critical relevance as chemotherapy is currently a standard treatment for those patients. From our results it could be suggested that hypoxia not only induces increased genetic instability, oncogenic properties and metastatization, but through the correlation observed with MVP expression, another pathway of chemo and radiation resistance could be developed.

Severe hypoxia induces chemo-resistance in clinical cervical tumors through MVP over-expression

International Nuclear Information System (INIS)

Lara, Pedro C; Lloret, Marta; Clavo, Bernardino; Apolinario, Rosa M; Henríquez-Hernández, Luis Alberto; Bordón, Elisa; Fontes, Fausto; Rey, Agustín

2009-01-01

Oxygen molecule modulates tumour response to radiotherapy. Higher radiation doses are required under hypoxic conditions to induce cell death. Hypoxia may inhibit the non-homologous end-joining DNA repair through down regulating Ku70/80 expression. Hypoxia induces drug resistance in clinical tumours, although the mechanism is not clearly elucidated. Vaults are ribonucleoprotein particles with a hollow barrel-like structure composed of three proteins: major vault protein (MVP), vault poly(ADP-ribose) polymerase, and telomerase associated protein-1 and small untranslated RNA. Over-expression of MVP has been associated with chemotherapy resistance. Also, it has been related to poor outcome in patients treated with radiotherapy alone. The aim of the present study was to assess the relation of Major Vault Protein expression and tumor hypoxia in clinical cervical tumors. MVP, p53 and angiogenesis, together with tumor oxygenation, were determined in forty-three consecutive patients suffering from localized cervix carcinoma. High MVP expression was related to severe hypoxia compared to low MVP expressing tumors (p = 0.022). Tumors over-expressing MVP also showed increased angiogenesis (p = 0.003). Besides it, in this study we show for the first time that severe tumor hypoxia is associated with high MVP expression in clinical cervical tumors. Up-regulation of MVP by hypoxia is of critical relevance as chemotherapy is currently a standard treatment for those patients. From our results it could be suggested that hypoxia not only induces increased genetic instability, oncogenic properties and metastatization, but through the correlation observed with MVP expression, another pathway of chemo and radiation resistance could be developed

The impact of intermittent or sustained carbon dioxide on intermittent hypoxia initiated respiratory plasticity. What is the effect of these combined stimuli on apnea severity?

Science.gov (United States)

Mateika, Jason H; Panza, Gino; Alex, Raichel; El-Chami, Mohamad

2017-10-31

The following review explores the effect that intermittent or sustained hypercapnia coupled to intermittent hypoxia has on respiratory plasticity. The review explores published work which suggests that intermittent hypercapnia leads to long-term depression of respiration when administered in isolation and prevents the initiation of long-term facilitation when administered in combination with intermittent hypoxia. The review also explores the impact that sustained hypercapnia alone and in combination with intermittent hypoxia has on the magnitude of long-term facilitation. After exploring the outcomes linked to intermittent hypoxia/hypercapnia and intermittent hypoxia/sustained hypercapnia the translational relevance of the outcomes as it relates to breathing stability during sleep is addressed. The likelihood that naturally induced cycles of intermittent hypoxia, coupled to oscillations in carbon dioxide that range between hypocapnia and hypercapnia, do not initiate long-term facilitation is addressed. Moreover, the conditions under which intermittent hypoxia/sustained hypercapnia could serve to improve breathing stability and mitigate co-morbidities associated with sleep apnea are considered. Published by Elsevier B.V.

The endogenous hallucinogen and trace amine N,N-dimethyltryptamine (DMT displays potent protective effects against hypoxia via sigma-1 receptor activation in human primary iPSC-derived cortical neurons and microglia-like immune cells

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Attila Szabo

2016-09-01

Full Text Available N,N-dimethyltryptamine (DMT is a potent endogenous hallucinogen present in the brain of humans and other mammals. Despite extensive research, its physiological role remains largely unknown. Recently, DMT has been found to activate the sigma-1 receptor (Sig-1R, an intracellular chaperone fulfilling an interface role between the endoplasmic reticulum (ER and mitochondria. It ensures the correct transmission of ER stress into the nucleus resulting in the enhanced production of antistress and antioxidant proteins. Due to this function, the activation of Sig-1R can mitigate the outcome of hypoxia or oxidative stress. In this paper we aimed to test the hypothesis that DMT plays a neuroprotective role in the brain by activating the Sig-1R. We tested whether DMT can mitigate hypoxic stress in in vitro cultured human cortical neurons (derived from induced pluripotent stem cells, and in monocyte-derived macrophages and dendritic cells. Here we report that DMT robustly increases the survival of these cell types in severe hypoxia (0.5% O2 through the Sig-1R. Furthermore, this phenomenon is associated with the decreased expression and function of the alpha subunit of the hypoxia-inducible factor 1 (HIF-1 suggesting that DMT-mediated Sig-1R activation may alleviate hypoxia-induced cellular stress and increase survival in a HIF-1-independent manner. Our results reveal a novel and important role of DMT in human cellular physiology. We postulate that this compound may be endogenously generated in situations of stress, ameliorating the adverse effects of hypoxic/ischemic insult to the brain.

The Endogenous Hallucinogen and Trace Amine N,N-Dimethyltryptamine (DMT) Displays Potent Protective Effects against Hypoxia via Sigma-1 Receptor Activation in Human Primary iPSC-Derived Cortical Neurons and Microglia-Like Immune Cells.

Science.gov (United States)

Szabo, Attila; Kovacs, Attila; Riba, Jordi; Djurovic, Srdjan; Rajnavolgyi, Eva; Frecska, Ede

2016-01-01

N,N-dimethyltryptamine (DMT) is a potent endogenous hallucinogen present in the brain of humans and other mammals. Despite extensive research, its physiological role remains largely unknown. Recently, DMT has been found to activate the sigma-1 receptor (Sig-1R), an intracellular chaperone fulfilling an interface role between the endoplasmic reticulum (ER) and mitochondria. It ensures the correct transmission of ER stress into the nucleus resulting in the enhanced production of antistress and antioxidant proteins. Due to this function, the activation of Sig-1R can mitigate the outcome of hypoxia or oxidative stress. In this paper, we aimed to test the hypothesis that DMT plays a neuroprotective role in the brain by activating the Sig-1R. We tested whether DMT can mitigate hypoxic stress in in vitro cultured human cortical neurons (derived from induced pluripotent stem cells, iPSCs), monocyte-derived macrophages (moMACs), and dendritic cells (moDCs). Results showed that DMT robustly increases the survival of these cell types in severe hypoxia (0.5% O2) through the Sig-1R. Furthermore, this phenomenon is associated with the decreased expression and function of the alpha subunit of the hypoxia-inducible factor 1 (HIF-1) suggesting that DMT-mediated Sig-1R activation may alleviate hypoxia-induced cellular stress and increase survival in a HIF-1-independent manner. Our results reveal a novel and important role of DMT in human cellular physiology. We postulate that this compound may be endogenously generated in situations of stress, ameliorating the adverse effects of hypoxic/ischemic insult to the brain.

What can an ecophysiological approach tell us about the physiological responses of marine invertebrates to hypoxia?

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Spicer, John I

2014-01-01

Hypoxia (low O2) is a common and natural feature of many marine environments. However, human-induced hypoxia has been on the rise over the past half century and is now recognised as a major problem in the world's seas and oceans. Whilst we have information on how marine invertebrates respond physiologically to hypoxia in the laboratory, we still lack understanding of how they respond to such stress in the wild (now and in the future). Consequently, here the question 'what can an ecophysiological approach tell us about physiological responses of marine invertebrates to hypoxia' is addressed. How marine invertebrates work in the wild when challenged with hypoxia is explored using four case studies centred on different hypoxic environments. The recent integration of the various -omics into ecophysiology is discussed, and a number of advantages of, and challenges to, successful integration are suggested. The case studies and -omic/physiology integration data are used to inform the concluding part of the review, where it is suggested that physiological responses to hypoxia in the wild are not always the same as those predicted from laboratory experiments. This is due to behaviour in the wild modifying responses, and therefore more than one type of 'experimental' approach is essential to reliably determine the actual response. It is also suggested that assuming it is known what a measured response is 'for' can be misleading and that taking parodies of ecophysiology seriously may impede research progress. This review finishes with the suggestion that an -omics approach is, and is becoming, a powerful method of understanding the response of marine invertebrates to environmental hypoxia and may be an ideal way of studying hypoxic responses in the wild. Despite centring on physiological responses to hypoxia, the review hopefully serves as a contribution to the discussion of what (animal) ecophysiology looks like (or should look like) in the 21st century.

Hypoxia: The Force that Drives Chronic Kidney Disease

Science.gov (United States)

Fu, Qiangwei; Colgan, Sean P; Shelley, Carl Simon

2016-01-01

In the United States the prevalence of end-stage renal disease (ESRD) reached epidemic proportions in 2012 with over 600,000 patients being treated. The rates of ESRD among the elderly are disproportionally high. Consequently, as life expectancy increases and the baby-boom generation reaches retirement age, the already heavy burden imposed by ESRD on the US health care system is set to increase dramatically. ESRD represents the terminal stage of chronic kidney disease (CKD). A large body of evidence indicating that CKD is driven by renal tissue hypoxia has led to the development of therapeutic strategies that increase kidney oxygenation and the contention that chronic hypoxia is the final common pathway to end-stage renal failure. Numerous studies have demonstrated that one of the most potent means by which hypoxic conditions within the kidney produce CKD is by inducing a sustained inflammatory attack by infiltrating leukocytes. Indispensable to this attack is the acquisition by leukocytes of an adhesive phenotype. It was thought that this process resulted exclusively from leukocytes responding to cytokines released from ischemic renal endothelium. However, recently it has been demonstrated that leukocytes also become activated independent of the hypoxic response of endothelial cells. It was found that this endothelium-independent mechanism involves leukocytes directly sensing hypoxia and responding by transcriptional induction of the genes that encode the β2-integrin family of adhesion molecules. This induction likely maintains the long-term inflammation by which hypoxia drives the pathogenesis of CKD. Consequently, targeting these transcriptional mechanisms would appear to represent a promising new therapeutic strategy. PMID:26847481

A preclinical model for noninvasive imaging of hypoxia-induced gene expression; comparison with an exogenous marker of tumor hypoxia

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Wen Bixiu; Burgman, Paul; Zanzonico, Pat; O' Donoghue, Joseph; Li, Gloria C.; Ling, C. Clifton [Memorial Sloan-Kettering Cancer Center, Department of Medical Physics, New York (United States); Cai Shangde; Finn, Ron [Memorial Sloan-Kettering Cancer Center, Department of Radiology, New York (United States); Serganova, Inna [Memorial Sloan-Kettering Cancer Center, Department of Neurology, New York (United States); Blasberg, Ronald; Gelovani, Juri [Memorial Sloan-Kettering Cancer Center, Department of Radiology, New York (United States); Memorial Sloan-Kettering Cancer Center, Department of Neurology, New York (United States)

2004-11-01

Hypoxia is associated with tumor aggressiveness and is an important cause of resistance to radiation therapy and chemotherapy. Assays of tumor hypoxia could provide selection tools for hypoxia-modifying treatments. The purpose of this study was to develop and characterize a rodent tumor model with a reporter gene construct that would be transactivated by the hypoxia-inducible molecular switch, i.e., the upregulation of HIF-1. The reporter gene construct is the herpes simplex virus 1-thymidine kinase (HSV1-tk) fused with the enhanced green fluorescent protein (eGFP) under the regulation of an artificial hypoxia-responsive enhancer/promoter. In this model, tumor hypoxia would up-regulate HIF-1, and through the hypoxia-responsive promoter transactivate the HSV1-tkeGFPfusion gene. The expression of this reporter gene can be assessed with the {sup 124}I-labeled reporter substrate 2'-fluoro-2'-deoxy-1-{beta}-d-arabinofuranosyl-5-iodouracil ({sup 124}I-FIAU), which is phosphorylated by the HSV1-tk enzyme and trapped in the hypoxic cells. Animal positron emission tomography (microPET) and phosphor plate imaging (PPI) were used in this study to visualize the trapped {sup 124}I-FIAU, providing a distribution of the hypoxia-induced molecular events. The distribution of {sup 124}I-FIAU was also compared with that of an exogenous hypoxic cell marker, {sup 18}F-fluoromisonidazole (FMISO). Our results showed that {sup 124}I-FIAU microPET imaging of the hypoxia-induced reporter gene expression is feasible, and that the intratumoral distributions of {sup 124}I-FIAU and {sup 18}F-FMISO are similar. In tumor sections, detailed radioactivity distributions were obtained with PPI which also showed similarity between {sup 124}I-FIAU and {sup 18}F-FMISO. This reporter system is sufficiently sensitive to detect hypoxia-induced transcriptional activation by noninvasive imaging and might provide a valuable tool in studying tumor hypoxia and in validating existing and future

Hypoxia-inducible factor-1 alpha has a key role in hypoxic preconditioning.

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Taie, Satoshi; Ono, Junichiro; Iwanaga, Yasuyuki; Tomita, Shuhei; Asaga, Takehiko; Chujo, Kosuke; Ueki, Masaaki

2009-08-01

Sublethal hypoxia induces tolerance to subsequent hypoxic insults in a process known as hypoxic preconditioning (HP). Hypoxia-inducible factor-1 alpha (HIF-1 alpha) is a key transcription protein involved in the mechanism of HP. In this study, we investigated the effects of HP on tissue oxygenation and expression of HIF-1 alpha gene targets in the brain using neural cell-specific HIF-1 alpha-deficient mice. The animals were exposed to 8% oxygen for 3 hours. Twenty-four hours later, the oxygen partial pressure (pO(2)) of brain tissue and gene expression were measured during hypoxia. HP improved the pO(2) of brain tissue during subsequent hypoxia with upregulated inducible nitric oxide synthase in wild-type mice, whereas HP had no detectable effect in the mutant mice. Our results indicate that the protective effects of HP may be partially mediated by improving tissue oxygenation via HIF-1 alpha and inducible nitric oxide synthase.

Hypoxia Induces Epithelial-Mesenchymal Transition in Follicular Thyroid Cancer: Involvement of Regulation of Twist by Hypoxia Inducible Factor-1α.

Science.gov (United States)

Yang, Yeon Ju; Na, Hwi Jung; Suh, Michelle J; Ban, Myung Jin; Byeon, Hyung Kwon; Kim, Won Shik; Kim, Jae Wook; Choi, Eun Chang; Kwon, Hyeong Ju; Chang, Jae Won; Koh, Yoon Woo

2015-11-01

Although follicular thyroid cancer (FTC) has a relatively fair prognosis, distant metastasis sometimes results in poor prognosis and survival. There is little understanding of the mechanisms contributing to the aggressiveness potential of thyroid cancer. We showed that hypoxia inducible factor-1α (HIF-1α) induced aggressiveness in FTC cells and identified the underlying mechanism of the HIF-1α-induced invasive characteristics. Cells were cultured under controlled hypoxic environments (1% O₂) or normoxic conditions. The effect of hypoxia on HIF-1α, and epithelial-to-mesenchymal transition (EMT) related markers were evaluated by quantitative real-time PCR, Western blot analysis and immunocytochemistry. Invasion and wound healing assay were conducted to identify functional character of EMT. The involvement of HIF-1α and Twist in EMT were studied using gene overexpression or silencing. After orthotopic nude mouse model was established using the cells transfected with lentiviral shHIF-1α, tissue analysis was done. Hypoxia induces HIF-1α expression and EMT, including typical morphologic changes, cadherin shift, and increased vimentin expression. We showed that overexpression of HIF-1α via transfection resulted in the aforementioned changes without hypoxia, and repression of HIF-1α with RNA interference suppressed hypoxia-induced HIF-1α and EMT. Furthermore, we also observed that Twist expression was regulated by HIF-1α. These were confirmed in the orthotopic FTC model. Hypoxia induced HIF-1α, which in turn induced EMT, resulting in the increased capacity for invasion and migration of cells via regulation of the Twist signal pathway in FTC cells. These findings provide insight into a possible therapeutic strategy to prevent invasive and metastatic FTC.

Dipeptidyl peptidase IV inhibition exerts renoprotective effects in rats with established heart failure

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Daniel Francisco De Arruda Junior

2016-07-01

Full Text Available Circulating dipeptidyl peptidase IV (DPPIV activity is associated with worse cardiovascular outcomes in humans and experimental heart failure (HF models, suggesting that DPPIV may play a role in the pathophysiology of this syndrome. Renal dysfunction is one of the key features of HF, but it remains to be determined whether DPPIV inhibitors are capable of improving cardiorenal function after the onset of HF. Therefore, the present study aimed to test the hypothesis that DPPIV inhibition by vildagliptin improves renal water and salt handling and exerts anti-proteinuric effects in rats with established HF. To this end, male Wistar rats were subjected to left ventricle (LV radiofrequency ablation or sham operation. Six weeks after surgery, radiofrequency-ablated rats who developed HF were randomly divided into two groups and treated for four weeks with vildagliptin (120 mg/kg/day or vehicle by oral gavage. Echocardiography was performed before (pretreatment and at the end of treatment (post-treatment to evaluate cardiac function. The fractional area change increased (34±5 vs. 45±3%, p<0.05, and the isovolumic relaxation time decreased (33±2 vs. 27±1 ms; p<0.05 in HF rats treated with vildagliptin (post-treatment vs. pretreatment. On the other hand, cardiac dysfunction deteriorated further in vehicle-treated HF rats. Renal function was impaired in vehicle-treated HF rats as evidenced by fluid retention, low glomerular filtration rate (GFR and high levels of urinary protein excretion. Vildagliptin treatment restored urinary flow, GFR, urinary sodium and urinary protein excretion to sham levels. Restoration of renal function in HF rats by DPPIV inhibition was associated with increased active glucagon-like peptide-1 (GLP-1 serum concentration, reduced DPPIV activity and increased activity of protein kinase A in the renal cortex. Furthermore, the anti-proteinuric effect of vildagliptin treatment in rats with established HF was associated with

Hypoxia-Inducible Factor 3 Is an Oxygen-Dependent Transcription Activator and Regulates a Distinct Transcriptional Response to Hypoxia

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Peng Zhang

2014-03-01

Full Text Available Hypoxia-inducible factors (HIFs play key roles in the cellular response to hypoxia. It is widely accepted that whereas HIF-1 and HIF-2 function as transcriptional activators, HIF-3 inhibits HIF-1/2α action. Contrary to this idea, we show that zebrafish Hif-3α has strong transactivation activity. Hif-3α is degraded under normoxia. Mutation of P393, P493, and L503 inhibits this oxygen-dependent degradation. Transcriptomics and chromatin immunoprecipitation analyses identify genes that are regulated by Hif-3α, Hif-1α, or both. Under hypoxia or when overexpressed, Hif-3α binds to its target gene promoters and upregulates their expression. Dominant-negative inhibition and knockdown of Hif-3α abolish hypoxia-induced Hif-3α-promoter binding and gene expression. Hif-3α not only mediates hypoxia-induced growth and developmental retardation but also possesses hypoxia-independent activities. Importantly, transactivation activity is conserved and human HIF-3α upregulates similar genes in human cells. These findings suggest that Hif-3 is an oxygen-dependent transcription factor and activates a distinct transcriptional response to hypoxia.

Hypoxia during pregnancy in rats leads to the changes of the cerebral white matter in adult offspring

International Nuclear Information System (INIS)

Wang, Lingxing; Cai, Ruowei; Lv, Guorong; Huang, Ziyang; Wang, Zhenhua

2010-01-01

The aim of the present study is to evaluate the effect of reduced fetal oxygen supply on cerebral white matter in the adult offspring and further assess its susceptibility to postnatal hypoxia and high-fat diet. Based on a 3 x 2 full factorial design consisting of three factors of maternal hypoxia, postnatal high-fat diet, and postnatal hypoxia, the ultrastructure of myelin, axon and capillaries were observed, and the expression of myelin basic protein (MBP), neurofilament-H+L(NF-H+L), and glial fibrillary acidic protein (GFAP) was analyzed in periventricular white matter of 16-month-old offspring. Demyelination, injured axon and damaged microvasculars were observed in maternal hypoxia offspring. The main effect of maternal hypoxia lead to decreased expression of MBP or NF-H+L, and increased expression of GFAP (all P < 0.05). Moreover, there was positive three-way interaction among maternal hypoxia, high-fat diet and postnatal hypoxia on MBP, NF-H+L or GFAP expression (all P < 0.05). In summary, our results indicated that maternal hypoxia during pregnancy in rats lead to changes of periventricular white matter in adult offspring, including demyelination, damaged axon and proliferated astroglia. This effect was amplified by high-fat diet and postnatal hypoxia.

Team Size and Stretching-Exercise Effects on Simulated Chest Compression Performance and Exertion

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Jessica C. Schoen

2017-09-01

Full Text Available Introduction: Investigators conducted a prospective experimental study to evaluate the effect of team size and recovery exercises on individual providers’ compression quality and exertion. Investigators hypothesized that 1 larger teams would perform higher quality compressions with less exertion per provider when compared to smaller teams; and 2 brief stretching and breathing exercises during rest periods would sustain compressor performance and mitigate fatigue. Methods: In Phase I, a volunteer cohort of pre-clinical medical students performed four minutes of continuous compressions on a Resusci-Anne manikin to gauge the spectrum of compressor performance in the subject population. Compression rate, depth, and chest recoil were measured. In Phase II, the highest-performing Phase I subjects were placed into 2-, 3-, and/or 4-compressor teams; 2-compressor teams were assigned either to control group (no recovery exercises or intervention group (recovery exercises during rest. All Phase II teams participated in 20-minute simulations with compressor rotation every two minutes. Investigators recorded compression quality and real-time heart rate data, and calculated caloric expenditure from contact heart rate monitor measurements using validated physiologic formulas. Results: Phase I subjects delivered compressions that were 24.9% (IQR1–3: [0.5%–74.1%] correct with a median rate of 112.0 (IQR1–3: [103.5–124.9] compressions per minute and depth of 47.2 (IQR1–3: [35.7–55.2] mm. In their first rotations, all Phase II subjects delivered compressions of similar quality and correctness (p=0.09. Bivariate analyses of 2-, 3-, and 4-compressor teams’ subject compression characteristics by subsequent rotation did not identify significant differences within or across teams. On multivariate analyses, only subjects in 2-compressor teams exhibited significantly lower compression rates (control subjects; p<0.01, diminished chest release (intervention

The effects of acclimatization on blood clotting parameters in exertional heat stress.

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Vesić, Zoran; Vukasinović-Vesić, Milica; Dincić, Dragan; Surbatović, Maja; Radaković, Sonja S

2013-07-01

Exertional heat stress is a common problem in military services. Considering the coagulation abnormalities are of major importance in development of severe heat stroke, we wanted to examine changes in hemostatic parameters in soldiers during exertional heat stress test as well as the effects of a 10-day passive or active acclimatization in a climatic chamber. A total of 40 male soldiers with high aerobic capacity performed exertional heat stress test (EHST) either in cool [20 degrees C, 16 degrees C wet bulb globe temperature (WBGT)], or hot (40 degrees C, 29 degrees C, (WBGT) environment, unacclimatized (U) or after 10 days of passive (P) or active (A) acclimatization. Physiological strain was measured by tympanic temperatures (Tty) and heart rates (HR). Platelet count (PC), antithrombin III (AT), and prothrombin time (PT) were assessed in blood samples collected before and immediately after the EHST. EHST in hot conditions induced physiological heat stress (increase in Tty and HR), with a significant increase in prothrombin time in the groups U and A. Platelet counts were significantly higher after the EHST compared to the basic levels in all the investigated groups, regardless environmental conditions and acclimatization state. Antithrombin levels were not affected by EHST whatsoever. In the trained soldiers, physiological heat stress caused mild changes in some serum parameters of blood clotting such as prothrombin time, while others such as antithrombin levels were not affected. Platelet counts were increased after EHST in all groups. A 10-day passive or active acclimatization in climatic chamber showed no effect on parameters investigated.

Do placebo expectations influence perceived exertion during physical exercise?

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Hendrik Mothes

Full Text Available This study investigates the role of placebo expectations in individuals' perception of exertion during acute physical exercise. Building upon findings from placebo and marketing research, we examined how perceived exertion is affected by expectations regarding a the effects of exercise and b the effects of the exercise product worn during the exercise. We also investigated whether these effects are moderated by physical self-concept. Seventy-eight participants conducted a moderate 30 min cycling exercise on an ergometer, with perceived exertion (RPE measured every 5 minutes. Beforehand, each participant was randomly assigned to 1 of 4 conditions and watched a corresponding film clip presenting "scientific evidence" that the exercise would or would not result in health benefits and that the exercise product they were wearing (compression garment would additionally enhance exercise benefits or would only be worn for control purposes. Participants' physical self-concept was assessed via questionnaire. Results partially demonstrated that participants with more positive expectations experienced reduced perceived exertion during the exercise. Furthermore, our results indicate a moderator effect of physical self-concept: Individuals with a high physical self-concept benefited (in terms of reduced perceived exertion levels in particular from an induction of generally positive expectations. In contrast, individuals with a low physical self-concept benefited when positive expectations were related to the exercise product they were wearing. In sum, these results suggest that placebo expectations may be a further, previously neglected class of psychological factors that influence the perception of exertion.

Effects of smoking cessation on hypoxia and its potential impact on radiation treatment effects in lung cancer patients

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Nieder, C. [Radiation Oncology Unit, Medical Dept., Nordlandssykehuset HF, Bodo (Norway); Inst. of Clinical Medicine, Faculty of Medicine, Univ. of Tromso (Norway); Bremnes, R.M. [Inst. of Clinical Medicine, Faculty of Medicine, Univ. of Tromso (Norway); Dept. of Oncology, Univ. Hospital of North Norway, Tromso (Norway)

2008-11-15

Background and purpose: smoking cessation is often attempted in the context of a lung cancer diagnosis. If cessation causes slowly continuing changes of total lung capacity and vital capacity, this may have consequences for lung volume, results of dose-volume histogram (DVH) analysis and targeting precision, in addition to changes in oxygenation, tumor biology (gene expression) and prognosis. Methods: to address the impact of smoking cessation on radiation treatment of lung cancer, a literature review was performed. Results: smoking cessation is associated with important benefits such as improved lung function and a better general health and performance status. In surgically and radiation treated patients, smoking cessation might lead to longer survival and reduced complications. Early data indicate that hypoxia in non-small cell lung cancer should be considered a poor prognostic factor. Yet, specific human data on how hypoxia is influenced by smoking status are not available. The influence of smoking history on the pneumonitis risk is not entirely clear. However, it appears that other factors outweigh the influence of smoking. The short-term effects of smoking cessation on lung function do not appear to cause relevant errors in treatment planning or targeting precision. Yet, no prospective study formally addressing this question was identified. Conclusion: smoking cessation appears to be prognostically beneficial. The role of hypoxia in this context requires more detailed evaluation. (orig.)

Intermittent hypoxia in childhood: the harmful consequences versus potential benefits of therapeutic uses

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Tatiana V. Serebrovskaya

2015-05-01

Full Text Available Intermittent hypoxia often occurs in early infancy in both preterm and term infants and especially at 36 to 44 weeks postmenstrual age. These episodes of intermittent hypoxia could result from sleep-disordered breathing or may be temporally unrelated to apnea or bradycardia events. There are numerous reports indicating adverse effects of intermittent hypoxia on development, behavior, academic achievement and cognition in children with sleep apnea syndrome. It remains uncertain the exact causative relationship between the neurocognitive and behavioral morbidities and intermittent hypoxia and/or its associated sleep fragmentation. On the other hand, well-controlled and moderate intermittent hypoxia conditioning/training has been used in sick children for treating their various forms of bronchial asthma, allergic dermatoses, autoimmune thyroiditis, cerebral palsy, and obesity. This review article provides an updated and impartial analysis on the currently available evidence in supporting either side of the seemingly contradictory scenarios. We wish to stimulate a comprehensive understanding of such a complex physiological phenomenon as intermittent hypoxia, which may be accompanied by other confounding factors (e.g. hypercapnia, polycythemia, in order to prevent or reduce its harmful consequences, while maximize its potential utility as an effective therapeutic tool in pediatric patients.

Hypoxia-Inducible Regulation of a Prodrug-Activating Enzyme for Tumor-Specific Gene Therapy

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Toru Shibata

2002-01-01

Full Text Available Previous studies have suggested that tumor hypoxia could be exploited for cancer gene therapy. Using hypoxia-responsive elements derived from the human vascular endothelial growth factor gene, we have generated vectors expressing a bacterial nitroreductase. (20NTR gene that can activate the anticancer prodrug CB1954. Stable transfectants of human HT1080 tumor cells with hypoxia-inducible vectors were established with G418 selection. Hypoxic induction of NTR protein correlated with increased sensitivity to in vitro exposure of HT 1080 cells to the prodrug. Growth delay assays were performed with established tumor xenografts derived from the same cells to detect the in vivo efficacy of CB1954 conversion to its cytotoxic form. Significant antitumor effects were achieved with intraperitoneal injections of CB1954 both in tumors that express NTR constitutively or with a hypoxia-inducible promoter. In addition, respiration of 10% O2 increased tumor hypoxia in vivo and enhanced the antitumor effects. Taken together, these results demonstrate that hypoxia-inducible vectors may be useful for tumor-selective gene therapy, although the problem of delivery of the vector to the tumors, particularly to the hypoxic cells in the tumors, is not addressed by these studies.

Tumor hypoxia and reoxygenation: the yin and yang for radiotherapy

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Hong, Beom Ju; Kim, Jong Woo; Jeong, Hoi Bin; Bok, Seo Yeon; Kim, Young Eun; Ahn, G One [Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang (Korea, Republic of)

2016-12-15

Tumor hypoxia, a common feature occurring in nearly all human solid tumors is a major contributing factor for failures of anticancer therapies. Because ionizing radiation depends heavily on the presence of molecular oxygen to produce cytotoxic effect, the negative impact of tumor hypoxia had long been recognized. In this review, we will highlight some of the past attempts to overcome tumor hypoxia including hypoxic radiosensitizers and hypoxia-selective cytotoxin. Although they were (still are) a very clever idea, they lacked clinical efficacy largely because of ‘reoxygenation’ phenomenon occurring in the conventional low dose hyperfractionation radiotherapy prevented proper activation of these compounds. Recent meta-analysis and imaging studies do however indicate that there may be a significant clinical benefit in lowering the locoregional failures by using these compounds. Latest technological advancement in radiotherapy has allowed to deliver high doses of radiation conformally to the tumor volume. Although this technology has brought superb clinical responses for many types of cancer, recent modeling studies have predicted that tumor hypoxia is even more serious because ‘reoxygenation’ is low thereby leaving a large portion of hypoxic tumor cells behind. Wouldn’t it be then reasonable to combine hypoxic radiosensitizers and/or hypoxia-selective cytotoxin with the latest radiotherapy? We will provide some preclinical and clinical evidence to support this idea hoping to revamp an enthusiasm for hypoxic radiosensitizers or hypoxia-selective cytotoxins as an adjunct therapy for radiotherapy.

Immunomodulatory Effects of the Mycosporine-Like Amino Acids Shinorine and Porphyra-334

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Kathrin Becker; Anja Hartmann; Markus Ganzera; Dietmar Fuchs; Johanna M. Gostner

2016-01-01

Mycosporine-like amino acids (MAAs) are secondary metabolites, produced by a large variety of microorganisms including algae, cyanobacteria, lichen and fungi. MAAs act as UV-absorbers and photo-protectants. MAAs are suggested to exert pharmaceutical relevant bioactivities in the human system. We particularly focused on their effect on defence and regulatory pathways that are active in inflamed environments. The MAAs shinorine and porphyra-334 were isolated and purified from the red algae Porp...

Hypoxia in tumors: pathogenesis-related classification, characterization of hypoxia subtypes, and associated biological and clinical implications.

Science.gov (United States)

Vaupel, Peter; Mayer, Arnulf

2014-01-01

Hypoxia is a hallmark of tumors leading to (mal-)adaptive processes, development of aggressive phenotypes and treatment resistance. Based on underlying mechanisms and their duration, two main types of hypoxia have been identified, coexisting with complex spatial and temporal heterogeneities. Chronic hypoxia is mainly caused by diffusion limitations due to enlarged diffusion distances and adverse diffusion geometries (e.g., concurrent vs. countercurrent microvessels, Krogh- vs. Hill-type diffusion geometry) and, to a lesser extent, by hypoxemia (e.g., in anemic patients, HbCO formation in heavy smokers), and a compromised perfusion or flow stop (e.g., due to disturbed Starling forces or intratumor solid stress). Acute hypoxia mainly results from transient disruptions in perfusion (e.g., vascular occlusion by cell aggregates), fluctuating red blood cell fluxes or short-term contractions of the interstitial matrix. In each of these hypoxia subtypes oxygen supply is critically reduced, but perfusion-dependent nutrient supply, waste removal, delivery of anticancer or diagnostic agents, and repair competence can be impaired or may not be affected. This detailed differentiation of tumor hypoxia may impact on our understanding of tumor biology and may aid in the development of novel treatment strategies, tumor detection by imaging and tumor targeting, and is thus of great clinical relevance.

Prolonged hypoxia modulates platelet activating factor receptor-mediated responses by fetal ovine pulmonary vascular smooth muscle cells.

Science.gov (United States)

Renteria, Lissette S; Raj, J Usha; Ibe, Basil O

2010-12-01

Hypoxia augments PAF receptor (PAFr) binding and PAFr protein expression in venous SMC (SMC-PV). We compared effect of acute and prolonged hypoxia (pO(2)<40 torr) on PAFr-mediated responses in arterial SMC (SMC-PA) and SMC-PV. Cells were studied for 30 min (acute) or for 48 h (prolonged) hypoxia and compared to normoxic (pO(2) ~100 torr) conditions. PAF binding was quantified in fmol/10(6) cells (mean ± SEM). PAF binding in normoxia were SMC-PA, 5.2 ± 0.2 and in SMC-PV, 19.3 ± 1.1; values in acute hypoxia were SMC-PA, 7.7 ± 0.4 and in SMC-PV, 27.8 ± 1.7. Prolonged hypoxia produced 6-fold increase in binding in SMC-PA, but only 2-fold increase in SMC-PV, but binding in SMC-PV was still higher. Acute hypoxia augmented inositol phosphate release by 50% and 40% in SMC-PA and SMC-PV, respectively. During normoxia, PAFr mRNA expression by both cell types was similar, but expression in hypoxia by SMC-PA was greater. In SMC-PA, hypoxia and PAF augmented intracellular calcium flux. Re-exposure of cells to 30 min normoxia after 48 h hypoxia decreased binding by 45-60%, suggesting immediate down-regulation of hypoxia-induced PAFr-mediated effects. We speculate that re-oxygenation immediately reverses hypoxia effect probably due to oxygen tension-dependent reversibility of PAFr activation and suggest that exposure of the neonate to prolonged state of hypoxia will vilify oxygen exchange capacity of the neonatal lungs. Copyright © 2010 Elsevier Inc. All rights reserved.

Angiotensin-(1-7 relieved renal injury induced by chronic intermittent hypoxia in rats by reducing inflammation, oxidative stress and fibrosis

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W. Lu

Full Text Available We aimed to study the renal injury and hypertension induced by chronic intermittent hypoxia (CIH and the protective effects mediated by angiotensin 1-7 [Ang(1-7]. We randomly assigned 32 male Sprague-Dawley rats (body weight 180-200 g to normoxia control, CIH, Ang(1-7-treated normoxia, and Ang(1-7-treated CIH groups. Systolic blood pressure (SBP was monitored at the start and end of each week. Renal sympathetic nerve activity (RSNA was recorded. CTGF and TGF-β were detected by immunohistochemistry and western blotting. Tissue parameters of oxidative stress were also determined. In addition, renal levels of interleukin-6, tumor necrosis factor-α, nitrotyrosine, and hypoxia-inducible factor-1α were determined by immunohistochemistry, immunoblotting, and ELISA. TUNEL assay results and cleaved caspase 3 and 12 were also determined. Ang(1-7 induced a reduction in SBP together with a restoration of RSNA in the rat model of CIH. Ang(1-7 treatment also suppressed the production of reactive oxygen species, reduced renal tissue inflammation, ameliorated mesangial expansion, and decreased renal fibrosis. Thus, Ang(1-7 treatment exerted renoprotective effects on CIH-induced renal injury and was associated with a reduction of oxidative stress, inflammation and fibrosis. Ang(1-7 might therefore represent a promising therapy for obstructive sleep apnea-related hypertension and renal injury.

Hypoxia perturbs aryl hydrocarbon receptor signaling and CYP1A1 expression induced by PCB 126 in human skin and liver-derived cell lines

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Vorrink, Sabine U. [Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA (United States); Department of Radiation Oncology, The University of Iowa, Iowa City, IA (United States); Severson, Paul L. [Department of Pharmacology and Toxicology, The University of Arizona, Tucson, AZ (United States); Kulak, Mikhail V. [Department of Surgery, The University of Iowa, Iowa City, IA (United States); Futscher, Bernard W. [Department of Pharmacology and Toxicology, The University of Arizona, Tucson, AZ (United States); Domann, Frederick E., E-mail: frederick-domann@uiowa.edu [Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA (United States); Department of Radiation Oncology, The University of Iowa, Iowa City, IA (United States); Department of Surgery, The University of Iowa, Iowa City, IA (United States)

2014-02-01

The aryl hydrocarbon receptor (AhR) is an important mediator of toxic responses after exposure to xenobiotics including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and dioxin-like polychlorinated biphenyls (PCBs). Activation of AhR responsive genes requires AhR dimerization with the aryl hydrocarbon receptor nuclear translocator (ARNT), a heterodimeric partner also shared by the hypoxia-inducible factor-1α (HIF-1α) protein. TCDD-stimulated AhR transcriptional activity can be influenced by hypoxia; however, it less well known whether hypoxia interferes with AhR transcriptional transactivation in the context of PCB-mediated AhR activation in human cells. Elucidation of this interaction is important in liver hepatocytes which extensively metabolize ingested PCBs and experience varying degrees of oxygen tension during normal physiologic function. This study was designed to assess the effect of hypoxia on AhR transcriptional responses after exposure to 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126). Exposure to 1% O{sub 2} prior to PCB 126 treatment significantly inhibited CYP1A1 mRNA and protein expression in human HepG2 and HaCaT cells. CYP1A1 transcriptional activation was significantly decreased upon PCB 126 stimulation under conditions of hypoxia. Additionally, hypoxia pre-treatment reduced PCB 126 induced AhR binding to CYP1 target gene promoters. Importantly, ARNT overexpression rescued cells from the inhibitory effect of hypoxia on XRE-luciferase reporter activity. Therefore, the mechanism of interference of the signaling crosstalk between the AhR and hypoxia pathways appears to be at least in part dependent on ARNT availability. Our results show that AhR activation and CYP1A1 expression induced by PCB 126 were significantly inhibited by hypoxia and hypoxia might therefore play an important role in PCB metabolism and toxicity. - Highlights: • Significant crosstalk exists between AhR and HIF-1α signaling. • Hypoxia perturbs PCB 126 induced AhR function and

Basolateral amygdalar D2 receptor activation is required for the companions-exerted suppressive effect on the cocaine conditioning.

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Tzeng, Wen-Yu; Cherng, Chian-Fang G; Yu, Lung; Wang, Ching-Yi

2017-01-01

The presence of companions renders decreases in cocaine-stimulated dopamine release in the nucleus accumbens and cocaine-induced conditioned place preference (CPP) magnitude. Limbic systems are widely believed to underlie the modulation of accumbal dopamine release and cocaine conditioning. Thus, this study aimed to assess whether intact basolateral nucleus of amygdala (BLA), dorsal hippocampus (DH), and dorsolateral striatum (DLS) is required for the companions-exerted suppressive effect on the cocaine-induced CPP. Three cage mates, serving as companions, were arranged to house with the experimental mice in the cocaine conditioning compartment throughout the cocaine conditioning sessions. Approximately 1week before the conditioning procedure, intracranial ibotenic acid infusions were done in an attempt to cause excitotoxic lesions targeting bilateral BLA, DH and DLS. Albeit their BLA, DH, and DLS lesions, the lesioned mice exhibited comparable cocaine-induced CPP magnitudes compared to the intact and sham lesion controls. Bilateral BLA, but not DH or DLS, lesions abolished the companions-exerted suppressive effect on the cocaine-induced CPP. Intact mice receiving intra-BLA infusion of raclopride, a selective D2 antagonist, 30min prior to the cocaine conditioning did not exhibit the companions-exerted suppressive effect on the cocaine-induced CPP. Intra-BLA infusion of Sch23390, a selective D1 antagonist, did not affect the companions-exerted suppressive effect on the CPP. These results, taken together, prompt us to conclude that the intactness of BLA is required for the companions-exerted suppressive effect on the cocaine-induced CPP. Importantly, activation of D2 receptor in the BLA is required for such suppressive effect on the CPP. Copyright © 2016 Elsevier Inc. All rights reserved.

Hypoxia induces adipogenic differentitation of myoblastic cell lines

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Itoigawa, Yoshiaki [Tohoku University School of Medicine, Sendai (Japan); Juntendo University School of Medicine, Tokyo (Japan); Kishimoto, Koshi N., E-mail: kishimoto@med.tohoku.ac.jp [Tohoku University School of Medicine, Sendai (Japan); Okuno, Hiroshi; Sano, Hirotaka [Tohoku University School of Medicine, Sendai (Japan); Kaneko, Kazuo [Juntendo University School of Medicine, Tokyo (Japan); Itoi, Eiji [Tohoku University School of Medicine, Sendai (Japan)

2010-09-03

Research highlights: {yields} C2C12 and G8 myogenic cell lines treated by hypoxia differentiate into adipocytes. {yields} The expression of C/EBP{beta}, {alpha} and PPAR{gamma} were increased under hypoxia. {yields} Myogenic differentiation of C2C12 was inhibited under hypoxia. -- Abstract: Muscle atrophy usually accompanies fat accumulation in the muscle. In such atrophic conditions as back muscles of kyphotic spine and the rotator cuff muscles with torn tendons, blood flow might be diminished. It is known that hypoxia causes trans-differentiation of mesenchymal stem cells derived from bone marrow into adipocytes. However, it has not been elucidated yet if hypoxia turned myoblasts into adipocytes. We investigated adipogenesis in C2C12 and G8 murine myogenic cell line treated by hypoxia. Cells were also treated with the cocktail of insulin, dexamethasone and IBMX (MDI), which has been known to inhibit Wnt signaling and promote adipogenesis. Adipogenic differentiation was seen in both hypoxia and MDI. Adipogenic marker gene expression was assessed in C2C12. CCAAT/enhancer-binding protein (C/EBP) {beta}, {alpha} and peroxisome proliferator activating receptor (PPAR) {gamma} were increased by both hypoxia and MDI. The expression profile of Wnt10b was different between hypoxia and MDI. The mechanism for adipogenesis of myoblasts in hypoxia might be regulated by different mechanism than the modification of Wnt signaling.

Combined effects of toxic cyanobacteria Microcystis aeruginosa and hypoxia on the physiological responses of triangle sail mussel Hyriopsis cumingii.

Science.gov (United States)

Hu, Menghong; Wu, Fangli; Yuan, Mingzhe; Liu, Qigen; Wang, Youji

2016-04-05

The single and combined effects of toxic cyanobacteria Microcystis aeruginosa and hypoxia on the energy budget of triangle sail mussel Hyriopsis cumingii were determined in terms of scope for growth (SfG). Mussels were exposed to different combinations of toxic M. aeruginosa (0%, 50%, and 100% of total dietary dry weight) and dissolved oxygen concentrations (1, 3, and 6.0mg O2l(-1)) with a 3×3 factorial design for 14 days, followed by a recovery period with normal conditions for 7 days. Microcystin contents in mussel tissues increased with the increase in the exposed M. aeruginosa concentration at each sampling time. Adverse physiological responses of H. cumingii under toxic M. aeruginosa and hypoxic exposure were found in terms of clearance rate, absorption efficiency, respiration rate, excretion rate, and SfG. Results emphasized the importance of combined effects of hypoxia and toxic cyanobacteria on H. cumingii bioenergetic parameters, highlighted the interactive effects of toxic algae and hypoxia, and implied that the two stressors affected H. cumingii during the exposure period and showed carryover effects later. Thus, if H. cumingii is used as a bioremediation tool to eliminate M. aeruginosa, the waters should be oxygenated. Copyright © 2015 Elsevier B.V. All rights reserved.

Fatty Acid Biosynthesis Inhibition Increases Reduction Potential in Neuronal Cells under Hypoxia

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Stephen A Brose

2016-11-01

Full Text Available Recently, we have reported a novel neuronal specific pathway for adaptation to hypoxia through increased fatty acid (FA biosynthesis (FAS followed by esterification into lipids. However, the biological role of this pathway under hypoxia remains to be elucidated. In the presented study, we have tested our hypothesis that activation of FAS maintains reduction potential and reduces lactoacidosis in neuronal cells under hypoxia. To address this hypothesis, we measured the effect of FAS inhibition on NADH2+/NAD+ and NADPH2+/NADP+ ratios, and lactic acid levels in neuronal SH-SY5Y cells exposed to normoxic and hypoxic conditions. FAS inhibitors, TOFA (inhibits Acetyl-CoA carboxylase and cerulenin (inhibits FA synthase, increased NADH2+/NAD+ and NADPH2+/NADP+ ratios under hypoxia. Further, FAS inhibition increased lactic acid under both normoxic and hypoxic conditions, and caused cytotoxicity under hypoxia but not normoxia. These results indicate that FA may serve as hydrogen acceptors under hypoxia, thus supporting oxidation reactions including anaerobic glycolysis. These findings may help to identify a radically different approach to attenuate hypoxia related pathophysiology in the nervous system including stroke.

Fatty Acid Biosynthesis Inhibition Increases Reduction Potential in Neuronal Cells under Hypoxia.

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Brose, Stephen A; Golovko, Svetlana A; Golovko, Mikhail Y

2016-01-01

Recently, we have reported a novel neuronal specific pathway for adaptation to hypoxia through increased fatty acid (FA) biosynthesis followed by esterification into lipids. However, the biological role of this pathway under hypoxia remains to be elucidated. In the presented study, we have tested our hypothesis that activation of FA synthesis maintains reduction potential and reduces lactoacidosis in neuronal cells under hypoxia. To address this hypothesis, we measured the effect of FA synthesis inhibition on [Formula: see text]/NAD + and [Formula: see text]/NADP + ratios, and lactic acid levels in neuronal SH-SY5Y cells exposed to normoxic and hypoxic conditions. FA synthesis inhibitors, TOFA (inhibits Acetyl-CoA carboxylase) and cerulenin (inhibits FA synthase), increased [Formula: see text]/NAD + and [Formula: see text]/NADP + ratios under hypoxia. Further, FA synthesis inhibition increased lactic acid under both normoxic and hypoxic conditions, and caused cytotoxicity under hypoxia but not normoxia. These results indicate that FA may serve as hydrogen acceptors under hypoxia, thus supporting oxidation reactions including anaerobic glycolysis. These findings may help to identify a radically different approach to attenuate hypoxia related pathophysiology in the nervous system including stroke.

MicroRNA-210 Modulates Endothelial Cell Response to Hypoxia and Inhibits the Receptor Tyrosine Kinase Ligand Ephrin-A3*S⃞

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Fasanaro, Pasquale; D'Alessandra, Yuri; Di Stefano, Valeria; Melchionna, Roberta; Romani, Sveva; Pompilio, Giulio; Capogrossi, Maurizio C.; Martelli, Fabio

2008-01-01

MicroRNAs (miRNAs) are small non-protein-coding RNAs that function as negative gene expression regulators. In the present study, we investigated miRNAs role in endothelial cell response to hypoxia. We found that the expression of miR-210 progressively increased upon exposure to hypoxia. miR-210 overexpression in normoxic endothelial cells stimulated the formation of capillary-like structures on Matrigel and vascular endothelial growth factor-driven cell migration. Conversely, miR-210 blockade via anti-miRNA transfection inhibited the formation of capillary-like structures stimulated by hypoxia and decreased cell migration in response to vascular endothelial growth factor. miR-210 overexpression did not affect endothelial cell growth in both normoxia and hypoxia. However, anti-miR-210 transfection inhibited cell growth and induced apoptosis, in both normoxia and hypoxia. We determined that one relevant target of miR-210 in hypoxia was Ephrin-A3 since miR-210 was necessary and sufficient to down-modulate its expression. Moreover, luciferase reporter assays showed that Ephrin-A3 was a direct target of miR-210. Ephrin-A3 modulation by miR-210 had significant functional consequences; indeed, the expression of an Ephrin-A3 allele that is not targeted by miR-210 prevented miR-210-mediated stimulation of both tubulogenesis and chemotaxis. We conclude that miR-210 up-regulation is a crucial element of endothelial cell response to hypoxia, affecting cell survival, migration, and differentiation. PMID:18417479

Teleosts in hypoxia : Aspects of anaerobic metabolism

NARCIS (Netherlands)

Van den Thillart, G.; van Waarde, Aren

1985-01-01

Moderate hypoxia can be tolerated by many fish species, while only some species survive severe hypoxia or anoxia. Hypoxia usually activates anaerobic glycolysis, which may be temporary when the animals are able to improve their oxygen extraction capacity. Switching over to aerobic metabolism allows

Hypoxia-induced cytotoxic drug resistance in osteosarcoma is independent of HIF-1Alpha.

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Jennifer Adamski

Full Text Available Survival rates from childhood cancer have improved dramatically in the last 40 years, such that over 80% of children are now cured. However in certain subgroups, including metastatic osteosarcoma, survival has remained stubbornly poor, despite dose intensive multi-agent chemotherapy regimens, and new therapeutic approaches are needed. Hypoxia is common in adult solid tumours and is associated with treatment resistance and poorer outcome. Hypoxia induces chemotherapy resistance in paediatric tumours including neuroblastoma, rhabdomyosarcoma and Ewing's sarcoma, in vitro, and this drug resistance is dependent on the oxygen-regulated transcription factor hypoxia inducible factor-1 (HIF-1. In this study the effects of hypoxia on the response of the osteosarcoma cell lines 791T, HOS and U2OS to the clinically relevant cytotoxics cisplatin, doxorubicin and etoposide were evaluated. Significant hypoxia-induced resistance to all three agents was seen in all three cell lines and hypoxia significantly reduced drug-induced apoptosis. Hypoxia also attenuated drug-induced activation of p53 in the p53 wild-type U2OS osteosarcoma cells. Drug resistance was not induced by HIF-1α stabilisation in normoxia by cobalt chloride nor reversed by the suppression of HIF-1α in hypoxia by shRNAi, siRNA, dominant negative HIF or inhibition with the small molecule NSC-134754, strongly suggesting that hypoxia-induced drug resistance in osteosarcoma cells is independent of HIF-1α. Inhibition of the phosphoinositide 3-kinase (PI3K pathway using the inhibitor PI-103 did not reverse hypoxia-induced drug resistance, suggesting the hypoxic activation of Akt in osteosarcoma cells does not play a significant role in hypoxia-induced drug resistance. Targeting hypoxia is an exciting prospect to improve current anti-cancer therapy and combat drug resistance. Significant hypoxia-induced drug resistance in osteosarcoma cells highlights the potential importance of hypoxia as a target

Early Life Exposure to Chronic Intermittent Hypoxia Primes Increased Susceptibility to Hypoxia-Induced Weakness in Rat Sternohyoid Muscle During Adulthood

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Fiona B Mcdonald

2016-03-01

Full Text Available Intermittent hypoxia is a feature of apnea of prematurity, chronic lung disease and sleep apnea. Despite the clinical relevance, the long-term effects of hypoxic exposure in early life on respiratory control are not well defined. We recently reported that exposure to chronic intermittent hypoxia (CIH during postnatal development (pCIH causes upper airway muscle weakness in both sexes, which persists for several weeks. We sought to examine if there are persistent sex-dependent effects of pCIH on respiratory muscle function into adulthood and/or increased susceptibility to re-exposure to CIH in adulthood in animals previously exposed to CIH during postnatal development. We hypothesized that pCIH would cause long-lasting muscle impairment and increased susceptibility to subsequent hypoxia. Within 24 hours of delivery, pups and their respective dams were exposed to CIH: 90s of hypoxia reaching 5% O2 at nadir; once every 5 min, 8 hrs per day for 3 weeks. Sham groups were exposed to normoxia in parallel. Three groups were studied: sham; pCIH; and pCIH combined with adult CIH (p+aCIH, where a subset of the pCIH-exposed pups were re-exposed to the same CIH paradigm beginning at 13 weeks. Following gas exposures, sternohyoid and diaphragm muscle isometric contractile and endurance properties were examined ex vivo. There was no apparent lasting effect of pCIH on respiratory muscle function in adults. However, in both males and females, re-exposure to CIH in adulthood in pCIH-exposed animals caused sternohyoid (but not diaphragm weakness. Exposure to this paradigm of CIH in adulthood alone had no effect on muscle function. Persistent susceptibility in pCIH-exposed airway dilator muscle to subsequent hypoxic insult may have implications for the control of airway patency in adult humans exposed to intermittent hypoxic stress during early life.

Early life exposure to chronic intermittent Hypoxia Primes Increased Susceptibility to Hypoxia-Induced Weakness in Rat Sternohyoid Muscle during adulthood.

LENUS (Irish Health Repository)

McDonald, Fiona B

2016-03-01

Intermittent hypoxia is a feature of apnea of prematurity (AOP), chronic lung disease, and sleep apnea. Despite the clinical relevance, the long-term effects of hypoxic exposure in early life on respiratory control are not well defined. We recently reported that exposure to chronic intermittent hypoxia (CIH) during postnatal development (pCIH) causes upper airway muscle weakness in both sexes, which persists for several weeks. We sought to examine if there are persistent sex-dependent effects of pCIH on respiratory muscle function into adulthood and\\/or increased susceptibility to re-exposure to CIH in adulthood in animals previously exposed to CIH during postnatal development. We hypothesized that pCIH would cause long-lasting muscle impairment and increased susceptibility to subsequent hypoxia. Within 24 h of delivery, pups and their respective dams were exposed to CIH: 90 s of hypoxia reaching 5% O2 at nadir; once every 5 min, 8 h per day for 3 weeks. Sham groups were exposed to normoxia in parallel. Three groups were studied: sham; pCIH; and pCIH combined with adult CIH (p+aCIH), where a subset of the pCIH-exposed pups were re-exposed to the same CIH paradigm beginning at 13 weeks. Following gas exposures, sternohyoid and diaphragm muscle isometric contractile and endurance properties were examined ex vivo. There was no apparent lasting effect of pCIH on respiratory muscle function in adults. However, in both males and females, re-exposure to CIH in adulthood in pCIH-exposed animals caused sternohyoid (but not diaphragm) weakness. Exposure to this paradigm of CIH in adulthood alone had no effect on muscle function. Persistent susceptibility in pCIH-exposed airway dilator muscle to subsequent hypoxic insult may have implications for the control of airway patency in adult humans exposed to intermittent hypoxic stress during early life.

Loss aversion and hypoxia: less loss aversion in oxygen-depleted environment.

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Pighin, Stefania; Bonini, Nicolao; Savadori, Lucia; Hadjichristidis, Constantinos; Schena, Federico

2014-03-01

Hypoxia, the deprivation of adequate oxygen supply, constitutes a direct threat to survival by disrupting cardiovascular or respiratory homeostasis and eliciting a respiratory distress. Although hypoxia has been shown to increase brain vulnerability and impair basic cognitive functions, only one study has examined its effect on decision-making. The present study examined the effect of mild hypoxia on individual's loss aversion, that is, the tendency to be more affected by losses than equal sized gains. A sample of 26 participants were asked to either accept or reject a series of mixed gambles once in an oxygen-depleted environment (14.1% oxygen concentration) and once in a normoxic environment (20.9% oxygen concentration). Each gamble involved a 50-50 chance of winning or losing specified amounts of money. Mild hypoxia decreased loss aversion: on average in the normoxic condition participants accepted gambles if the gain was at least 2.4 times as large as the loss, whereas in the oxygen-depleted condition participants accepted gambles if the gain was at least 1.7 times as large as the loss. Mild hypoxia may push individuals to be less cautious in daily decisions that involve a trade-off between a gain and a loss.

Update: Exertional rhabdomyolysis, active component, U.S. Armed Forces, 2012-2016.

Science.gov (United States)

2017-03-01

Among active component service members in 2016, there were 525 incident diagnoses of rhabdomyolysis likely due to physical exertion and/or heat stress ("exertional rhabdomyolysis"). The crude incidence rate in 2016 was 40.7 cases per 100,000 person-years. Annual rates of incident diagnoses of exertional rhabdomyolysis increased 46.2% between 2013 and 2016, with the greatest percentage change occurring between 2014 and 2015. In 2016, relative to their respective counterparts, the highest incidence rates of exertional rhabdomyolysis affected service members who were male; younger than 20 years of age; and black, non-Hispanic. During the surveillance period, annual incidence rates were highest among service members of the Marine Corps, intermediate among those in the Army, and lowest among those in the Air Force and Navy. Most cases of exertional rhabdomyolysis were diagnosed at installations that support basic combat/recruit training or major ground combat units of the Army or the Marine Corps. Medical care providers should consider exertional rhabdomyolysis in the differential diagnosis when service members (particularly recruits) present with muscular pain or swelling, limited range of motion, or the excretion of dark urine (possibly due to myoglobinuria) after strenuous physical activity, particularly in hot, humid weather.

Effects of natural and human-induced hypoxia on coastal benthos

Digital Repository Service at National Institute of Oceanography (India)

Levin, L.A.; Ekau, W.; Gooday, A.J.; Jorissen, F.; Middelburg, J.J.; Naqvi, S.W.A.; Neira, C.; Rabalais, N.N.; Zhang, J.

have been recorded from Hood Canal (Puget Sound), Los Alamitos and Newport Bay, with nutrient enrichment implicated. Estuar- ine hypoxia is of widespread concern because estuaries sup- port major shellfisheries (oysters, scallops, clams), provide...

Mitochondrial Reactive Oxygen Species and Kidney Hypoxia in the Development of Diabetic Nephropathy.

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Schiffer, Tomas A; Friederich-Persson, Malou

2017-01-01

The underlying mechanisms in the development of diabetic nephropathy are currently unclear and likely consist of a series of dynamic events from the early to late stages of the disease. Diabetic nephropathy is currently without curative treatments and it is acknowledged that even the earliest clinical manifestation of nephropathy is preceded by an established morphological renal injury that is in turn preceded by functional and metabolic alterations. An early manifestation of the diabetic kidney is the development of kidney hypoxia that has been acknowledged as a common pathway to nephropathy. There have been reports of altered mitochondrial function in the diabetic kidney such as altered mitophagy, mitochondrial dynamics, uncoupling, and cellular signaling through hypoxia inducible factors and AMP-kinase. These factors are also likely to be intertwined in a complex manner. In this review, we discuss how these pathways are connected to mitochondrial production of reactive oxygen species (ROS) and how they may relate to the development of kidney hypoxia in diabetic nephropathy. From available literature, it is evident that early correction and/or prevention of mitochondrial dysfunction may be pivotal in the prevention and treatment of diabetic nephropathy.

Normobaric hypoxia training: the effects of breathing-gas flow rate on symptoms.

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Artino, Anthony R; Folga, Richard V; Vacchiano, Charles

2009-06-01

The U.S. Navy has replaced segments of refresher low-pressure chamber instruction with normobaric hypoxia training using a reduced oxygen breathing device (ROBD). A previous training evaluation revealed that this alternative instructional paradigm is a preferred means of training experienced jet aviators to recognize and recover from hypoxia. However, findings from this earlier work also indicated that air hunger was the most commonly reported symptom during ROBD training. This finding raised concern that air hunger could have resulted from a training artifact caused by the lower breathing-gas flow rate produced by the ROBD when compared to more familiar jet aircraft breathing systems. In an effort to address this issue, a software change was made that increased ROBD mask flow from 30 to 50 L x min(-1) (LPM). The purpose of this retrospective study was to determine if there are differences in the hypoxia symptoms reported by aviators trained on the ROBD upgrade (ROBD-50) compared to those trained on the original device (ROBD-30). Hypoxia training was provided to 156 aviators using the ROBD-50, and survey results were compared to those obtained from 121 aviators trained on the ROBD-30. There was a significant decrease in the number of aviators who reported experiencing air hunger while training on the ROBD-50 (44.2%) as compared to the ROBD-30 (59.4%) [Pearson chi2 (1) = 5.45, P hunger and, therefore, may impact training fidelity.

Simulated reduction of hypoxia in the northern Gulf of Mexico due to phosphorus limitation

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Arnaud Laurent

2014-02-01

Full Text Available Abstract Excess nutrient loading from the Mississippi-Atchafalaya River system promotes the seasonal development of hypoxic bottom waters on the Louisiana shelf with detrimental effects on the benthic fauna. In the Mississippi River plume, primary production becomes phosphorus-limited between May and July at the peak of nutrient loading, displacing a portion of primary production and depositional fluxes westward. Here we quantitatively assessed, for the first time, the effect of phosphorus limitation on hypoxia development in the Mississippi-Atchafalaya River plume using a realistic physical-biogeochemical model. Results indicate that, despite a redistribution of respiration processes toward the western shelf, phosphorus limitation does not promote a westward expansion or relocation of hypoxia, as previously speculated. Rather, the onset of hypoxia was delayed and the size of the hypoxic zone reduced. Sensitivity experiments showed that this feature is robust in our model. Results from simulations with altered river input indicate that, despite phosphorus limitation, the co-reduction of nitrogen and phosphorus loads remains the best strategy to reduce hypoxia. Yet, even though nutrient load reductions have an immediate effect on hypoxia in this analysis, a 50% reduction in both nutrients will not be sufficient to meet the Gulf Hypoxia action plan goal of a 5·103 km2 hypoxic area.

Modification of the radioprotective effect of hypoxic hypoxia by the artificial hibernation of the organism

International Nuclear Information System (INIS)

Ovakimov, V.G.; Yarmonenko, S.P.; Akademiya Meditsinskikh Nauk SSSR, Moscow. Inst. Ehksperimental'noj i Klinicheskoj Onkologii)

1975-01-01

A significant weakening of the radioprotective effect of hypoxic hypoxia has been noted in the hibernated mice the resistance of which to acute oxygen deficiency is artificially hibernated (hypothermia under conditions of neuroplegia). The dose decrease factor is about 1.27 and 2.5 for hibernated and nonhibernated animals, respectively

The effects of superset configuration on kinetic, kinematic, and perceived exertion in the barbell bench press.

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Weakley, Jonathon Js; Till, Kevin; Read, Dale B; Phibbs, Padraic J; Roe, Gregory; Darrall-Jones, Joshua; Jones, Ben L

2017-08-04

Training that is efficient and effective is of great importance to an athlete. One method of improving efficiency is by incorporating supersets into resistance training routines. However, the structuring of supersets is still unexplored. Therefore, the purpose of this study was to assess the effects of agonist-antagonist (A-A), alternate peripheral (A-P), and similar biomechanical (SB) superset configurations on rate of perceived exertion (RPE), kinetic and kinematic changes during the bench press. 10 subjects performed resistance training protocols in a randomized-crossover design, with magnitude-based inferences assessing changes/differences within and between protocols. Changes in RPE were very likely and almost certainly greater in the A-P and SB protocols when compared with the A-A, while all superset protocols had very likely to almost certain reductions in mean velocity and power from baseline. Reductions in mean velocity and power were almost certainly greater in the SB protocol, with differences between the A-A and A-P protocols being unclear. Decreases in peak force were likely and almost certain in the A-A and SB protocols respectively, with changes in A-P being unclear. Differences between these protocols showed likely greater decreases in SB peak forces when compared to A-A, with all other superset comparisons being unclear. This study demonstrates the importance of exercise selection when incorporating supersets into a training routine. It is suggested that the practitioner uses A-A supersets when aiming to improve training efficiency and minimize reductions in kinetic and kinematic output of the agonist musculature while completing the barbell bench press.

Heterogeneous role of the glutathione antioxidant system in modulating the response of ESFT to fenretinide in normoxia and hypoxia.

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Tapiwanashe Magwere

Full Text Available Glutathione (GSH is implicated in drug resistance mechanisms of several cancers and is a key regulator of cell death pathways within cells. We studied Ewing's sarcoma family of tumours (ESFT cell lines and three mechanistically distinct anticancer agents (fenretinide, doxorubicin, and vincristine to investigate whether the GSH antioxidant system is involved in the reduced sensitivity to these chemotherapeutic agents in hypoxia. Cell viability and death were assessed by the trypan blue exclusion assay and annexin V-PI staining, respectively. Hypoxia significantly decreased the sensitivity of all ESFT cell lines to fenretinide-induced death, whereas the effect of doxorubicin or vincristine was marginal and cell-line-specific. The response of the GSH antioxidant system in ESFT cell lines to hypoxia was variable and also cell-line-specific, although the level of GSH appeared to be most dependent on de novo biosynthesis rather than recycling. RNAi-mediated knockdown of key GSH regulatory enzymes γ-glutamylcysteine synthetase or glutathione disulfide reductase partially reversed the hypoxia-induced resistance to fenretinide, and increasing GSH levels using N-acetylcysteine augmented the hypoxia-induced resistance in a cell line-specific manner. These observations are consistent with the conclusion that the role of the GSH antioxidant system in modulating the sensitivity of ESFT cells to fenretinide is heterogeneous depending on environment and cell type. This is likely to limit the value of targeting GSH as a therapeutic strategy to overcome hypoxia-induced drug resistance in ESFT. Whether targeting the GSH antioxidant system in conjunction with other therapeutics may benefit some patients with ESFT remains to be seen.

Uncoupling protein-2 mRNA expression in mice subjected to intermittent hypoxia

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Luciana Rodrigues Vieira

2015-04-01

Full Text Available Objective: To investigate the effect of intermittent hypoxia-a model of obstructive sleep apnea (OSA-on pancreatic expression of uncoupling protein-2 (UCP2, as well as on glycemic and lipid profiles, in C57BL mice. Methods: For 8 h/day over a 35-day period, male C57BL mice were exposed to intermittent hypoxia (hypoxia group or to a sham procedure (normoxia group. The intermittent hypoxia condition involved exposing mice to an atmosphere of 92% N and 8% CO2 for 30 s, progressively reducing the fraction of inspired oxygen to 8 ± 1%, after which they were exposed to room air for 30 s and the cycle was repeated (480 cycles over the 8-h experimental period. Pancreases were dissected to isolate the islets. Real-time PCR was performed with TaqMan assays. Results: Expression of UCP2 mRNA in pancreatic islets was 20% higher in the normoxia group than in the hypoxia group (p = 0.11. Fasting serum insulin was higher in the hypoxia group than in the normoxia group (p = 0.01. The homeostasis model assessment of insulin resistance indicated that, in comparison with the control mice, the mice exposed to intermittent hypoxia showed 15% lower insulin resistance (p = 0.09 and 21% higher pancreatic β-cell function (p = 0.01. Immunohistochemical staining of the islets showed no significant differences between the two groups in terms of the area or intensity of α- and β-cell staining for insulin and glucagon. Conclusions: To our knowledge, this is the first report of the effect of intermittent hypoxia on UCP2 expression. Our findings suggest that UCP2 regulates insulin production in OSA. Further study of the role that UCP2 plays in the glycemic control of OSA patients is warranted.

Glycogen synthesis is induced in hypoxia by the hypoxia-inducible factor and promotes cancer cell survival

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Joffrey ePelletier

2012-02-01

Full Text Available The hypoxia-inducible factor 1 (HIF-1, in addition to genetic and epigenetic changes, is largely responsible for alterations in cell metabolism in hypoxic tumor cells. This transcription factor not only favors cell proliferation through the metabolic shift from oxidative phosphorylation to glycolysis and lactic acid production but also stimulates nutrient supply by mediating adaptive survival mechanisms. In this study we showed that glycogen synthesis is enhanced in non-cancer and cancer cells when exposed to hypoxia, resulting in a large increase in glycogen stores. Furthermore, we demonstrated that the mRNA and protein levels of the first enzyme of glycogenesis, phosphoglucomutase1 (PGM1, were increased in hypoxia. We showed that induction of glycogen storage as well as PGM1 expression were dependent on HIF-1 and HIF-2. We established that hypoxia-induced glycogen stores are rapidly mobilized in cells that are starved of glucose. Glycogenolysis allows these hypoxia-preconditioned cells to confront and survive glucose deprivation. In contrast normoxic control cells exhibit a high rate of cell death following glucose removal. These findings point to the important role of hypoxia and HIF in inducing mechanisms of rapid adaptation and survival in response to a decrease in oxygen tension. We propose that a decrease in pO2 acts as an alarm that prepares the cells to face subsequent nutrient depletion and to survive.

Glycogen Synthesis is Induced in Hypoxia by the Hypoxia-Inducible Factor and Promotes Cancer Cell Survival

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Pelletier, Joffrey; Bellot, Grégory [Institute of Developmental Biology and Cancer Research, CNRS-UMR 6543, Centre Antoine Lacassagne, University of Nice-Sophia Antipolis, Nice (France); Gounon, Pierre; Lacas-Gervais, Sandra [Centre Commun de Microscopie Appliquée, University of Nice-Sophia Antipolis, Nice (France); Pouysségur, Jacques; Mazure, Nathalie M., E-mail: mazure@unice.fr [Institute of Developmental Biology and Cancer Research, CNRS-UMR 6543, Centre Antoine Lacassagne, University of Nice-Sophia Antipolis, Nice (France)

2012-02-28

The hypoxia-inducible factor 1 (HIF-1), in addition to genetic and epigenetic changes, is largely responsible for alterations in cell metabolism in hypoxic tumor cells. This transcription factor not only favors cell proliferation through the metabolic shift from oxidative phosphorylation to glycolysis and lactic acid production but also stimulates nutrient supply by mediating adaptive survival mechanisms. In this study we showed that glycogen synthesis is enhanced in non-cancer and cancer cells when exposed to hypoxia, resulting in a large increase in glycogen stores. Furthermore, we demonstrated that the mRNA and protein levels of the first enzyme of glycogenesis, phosphoglucomutase1 (PGM1), were increased in hypoxia. We showed that induction of glycogen storage as well as PGM1 expression were dependent on HIF-1 and HIF-2. We established that hypoxia-induced glycogen stores are rapidly mobilized in cells that are starved of glucose. Glycogenolysis allows these “hypoxia-preconditioned” cells to confront and survive glucose deprivation. In contrast normoxic control cells exhibit a high rate of cell death following glucose removal. These findings point to the important role of hypoxia and HIF in inducing mechanisms of rapid adaptation and survival in response to a decrease in oxygen tension. We propose that a decrease in pO{sub 2} acts as an “alarm” that prepares the cells to face subsequent nutrient depletion and to survive.

Glycogen Synthesis is Induced in Hypoxia by the Hypoxia-Inducible Factor and Promotes Cancer Cell Survival

International Nuclear Information System (INIS)

Pelletier, Joffrey; Bellot, Grégory; Gounon, Pierre; Lacas-Gervais, Sandra; Pouysségur, Jacques; Mazure, Nathalie M.

2012-01-01

The hypoxia-inducible factor 1 (HIF-1), in addition to genetic and epigenetic changes, is largely responsible for alterations in cell metabolism in hypoxic tumor cells. This transcription factor not only favors cell proliferation through the metabolic shift from oxidative phosphorylation to glycolysis and lactic acid production but also stimulates nutrient supply by mediating adaptive survival mechanisms. In this study we showed that glycogen synthesis is enhanced in non-cancer and cancer cells when exposed to hypoxia, resulting in a large increase in glycogen stores. Furthermore, we demonstrated that the mRNA and protein levels of the first enzyme of glycogenesis, phosphoglucomutase1 (PGM1), were increased in hypoxia. We showed that induction of glycogen storage as well as PGM1 expression were dependent on HIF-1 and HIF-2. We established that hypoxia-induced glycogen stores are rapidly mobilized in cells that are starved of glucose. Glycogenolysis allows these “hypoxia-preconditioned” cells to confront and survive glucose deprivation. In contrast normoxic control cells exhibit a high rate of cell death following glucose removal. These findings point to the important role of hypoxia and HIF in inducing mechanisms of rapid adaptation and survival in response to a decrease in oxygen tension. We propose that a decrease in pO 2 acts as an “alarm” that prepares the cells to face subsequent nutrient depletion and to survive.

Vascular parameters continue to decrease post-exposure with simultaneous, but not individual exposure to BPA and hypoxia in zebrafish larvae.

Science.gov (United States)

Cypher, Alysha D; Fetterman, Bryce; Bagatto, Brian

2018-04-01

How fish respond to hypoxia, a common stressor, can be altered by simultaneous exposure to pollutants like bisphenol A (BPA), a plasticizer. BPA is cardiotoxic and interferes with the hypoxia inducible factor pathway (HIF-1α), therefore disrupting the hypoxic response. Co-exposure to hypoxia and BPA also causes severe bradycardia and reduced cardiac output in zebrafish larvae. The purpose of this work was to determine how the cardiovascular effects of co-exposure vary with BPA concentration and persist beyond exposure. Zebrafish embryos were exposed to 0, 0.01, 0.1, 1, and 100 μg/L of BPA during normoxia (>6.0 mg/L O 2 ) and hypoxia (2.0 ± 0.5 mg/L O 2 ) between 1 h post fertilization (hpf) and late hatching (72-96 hpf). Heart rate, cardiac output, and red blood cell (RBC) velocity were determined through video microscopy and digital motion analysis at late hatching and 10 days post fertilization (dpf), several days post exposure. In comparison to the hypoxic control, RBC velocity was 25% lower with 0.01 μg/L BPA and hypoxia at late hatching. At 10 dpf, the difference in RBC velocity between these treatments doubled, despite several days of recovery. This coincided with a 24% thinner outer diameter for caudal vein but no effect on cardiac or developmental parameters. Statistical interactions between BPA and oxygen concentration were found for arterial RBC velocity at both ages. Because the co-occurrence of both stressors is extremely common, it would be beneficial to understand how BPA and hypoxia interact to affect cardiovascular function during and after exposure. Copyright © 2018 Elsevier Inc. All rights reserved.