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Sample records for intrinsic hypoxia markers

  1. Hypoxia in human colorectal adenocarcinoma: Comparison between extrinsic and potential intrinsic hypoxia markers

    SciTech Connect

    Goethals, Laurence; Debucquoy, Annelies; Perneel, Christiaan; Geboes, Karel; Ectors, Nadine; De Schutter, Harlinde; Penninckx, Freddy; McBride, William H.; Begg, Adrian C.; Haustermans, Karin M. . E-mail: karin.haustermans@uzleuven.be

    2006-05-01

    Purpose: To detect and quantify hypoxia in colorectal adenocarcinomas by use of pimonidazole and iododeoxyuridine (IdUrd) as extrinsic markers and carbonic anhydrase IX (CA IX), microvessel density (MVD), epidermal growth-factor receptor (EGFR), and vascular endothelial growth factor (VEGF) as intrinsic markers of hypoxia. Methods and Material: Twenty patients with an adenocarcinoma of the left colon and rectum treated by primary surgery were injected with pimonidazole and IdUrd. Serial sections of tumor biopsies were single stained for VEGF, EGFR, Ki67, and double stained for blood vessels in combination with either pimonidazole, IdUrd, or CA IX. Percentage of expression was scored as well as colocalization of pimonidazole with CA IX. Results: The median percentage of hypoxia, as judged by pimonidazole staining, was 16.7% (range, 0-52.4%). The expression of pimonidazole correlated inversely with the total MVD and endothelial cord MVD (R = -0.55, p = 0.01; R = -0.47, p = 0.04). Good colocalization was found between pimonidazole and CA IX in only 30% of tumors, with no correlation overall between pimonidazole and CA IX, VEGF, or EGFR or between the different intrinsic markers. Cells around some vessels (0.08-11%) were negative for IdUrd but positive for Ki 67, which indicated their lack of perfusion at the time of injection. Conclusion: Chronic and acute hypoxic regions are present in colorectal tumors, as shown by pimonidazole and IdUrd staining. Only in a minority of tumors did an association exist between the areas stained by pimonidazole and those positive for CA IX. Pimonidazole also did not correlate with expression of other putative intrinsic hypoxia markers (VEGF, EGFR)

  2. Overexpression of Intrinsic Hypoxia Markers HIF1{alpha} and CA-IX Predict for Local Recurrence in Stage T1-T2 Glottic Laryngeal Carcinoma Treated With Radiotherapy

    SciTech Connect

    Schrijvers, M.L.; Laan, B.F.A.M. van der; Bock, G.H. de; Pattje, W.J.; Mastik, M.F.; Menkema, L.; Langendijk, J.A.; Kluin, P.M.; Schuuring, E.; Wal, J.E. van der

    2008-09-01

    Purpose: To examine the prognostic value of three endogenous hypoxia markers (hypoxia inducible factor 1 {alpha} subunit [HIF1{alpha}], carbonic anhydrase IX [CA-IX], and glucose transporter type 1 [GLUT-1]) on the clinical outcome in patients with early-stage glottic carcinoma primarily treated with radiotherapy (RT) and to determine the predictive hypoxic profile to choose the optimal treatment of early-stage laryngeal carcinoma. Methods and Materials: Immunohistochemistry for HIF1{alpha}, CA-IX, and GLUT-1 was performed on formalin-fixed, paraffin-embedded, pretreatment tissue samples of 91 glottic squamous cell carcinoma specimens. The patient group consisted only of those with early-stage (T1-T2) glottic carcinoma, and all patients were treated with RT only. Relative tumor staining was scored on the tissue samples. Receiver operating curve analysis was performed to determine the optimal cutoff value for each tumor marker. Cox regression analyses for the variables HIF1{alpha}, CA-IX, GLUT-1, gender, age, hemoglobin level, T category, N category, tobacco use, and alcohol use were performed with local control and overall survival as endpoints. Results: HIF1{alpha} overexpression in early-stage glottic carcinoma correlated significantly with worse local control (hazard ratio [HR], 3.05; p = 0.021) and overall survival (HR, 2.92; p = 0.016). CA-IX overexpression correlated significantly with worse local control (HR, 2.93; p = 0.020). GLUT-1 overexpression did not show any correlation with the clinical outcome parameters. Tumors with a nonhypoxic profile (defined as low HIF1{alpha} and low CA-IX expression) had significantly better local control (HR, 6.32; p 0.013). Conclusion: The results of our study have shown that early-stage glottic laryngeal carcinomas with low HIF1{alpha} and CA-IX expression are highly curable with RT. For this group, RT is a good treatment option. For tumors with HIF1{alpha} or CA-IX overexpression, hypoxic modification before RT or primary

  3. Understanding oceanic migrations with intrinsic biogeochemical markers.

    PubMed

    Ramos, Raül; González-Solís, Jacob; Croxall, John P; Oro, Daniel; Ruiz, Xavier

    2009-01-01

    Migratory marine vertebrates move annually across remote oceanic water masses crossing international borders. Many anthropogenic threats such as overfishing, bycatch, pollution or global warming put millions of marine migrants at risk especially during their long-distance movements. Therefore, precise knowledge about these migratory movements to understand where and when these animals are more exposed to human impacts is vital for addressing marine conservation issues. Because electronic tracking devices suffer from several constraints, mainly logistical and financial, there is emerging interest in finding appropriate intrinsic markers, such as the chemical composition of inert tissues, to study long-distance migrations and identify wintering sites. Here, using tracked pelagic seabirds and some of their own feathers which were known to be grown at different places and times within the annual cycle, we proved the value of biogeochemical analyses of inert tissue as tracers of marine movements and habitat use. Analyses of feathers grown in summer showed that both stable isotope signatures and element concentrations can signal the origin of breeding birds feeding in distinct water masses. However, only stable isotopes signalled water masses used during winter because elements mainly accumulated during the long breeding period are incorporated into feathers grown in both summer and winter. Our findings shed new light on the simple and effective assignment of marine organisms to distinct oceanic areas, providing new opportunities to study unknown migration patterns of secretive species, including in relation to human-induced mortality on specific populations in the marine environment. PMID:19623244

  4. Understanding Oceanic Migrations with Intrinsic Biogeochemical Markers

    PubMed Central

    Ramos, Raül; González-Solís, Jacob; Croxall, John P.; Oro, Daniel

    2009-01-01

    Migratory marine vertebrates move annually across remote oceanic water masses crossing international borders. Many anthropogenic threats such as overfishing, bycatch, pollution or global warming put millions of marine migrants at risk especially during their long-distance movements. Therefore, precise knowledge about these migratory movements to understand where and when these animals are more exposed to human impacts is vital for addressing marine conservation issues. Because electronic tracking devices suffer from several constraints, mainly logistical and financial, there is emerging interest in finding appropriate intrinsic markers, such as the chemical composition of inert tissues, to study long-distance migrations and identify wintering sites. Here, using tracked pelagic seabirds and some of their own feathers which were known to be grown at different places and times within the annual cycle, we proved the value of biogeochemical analyses of inert tissue as tracers of marine movements and habitat use. Analyses of feathers grown in summer showed that both stable isotope signatures and element concentrations can signal the origin of breeding birds feeding in distinct water masses. However, only stable isotopes signalled water masses used during winter because elements mainly accumulated during the long breeding period are incorporated into feathers grown in both summer and winter. Our findings shed new light on the simple and effective assignment of marine organisms to distinct oceanic areas, providing new opportunities to study unknown migration patterns of secretive species, including in relation to human-induced mortality on specific populations in the marine environment. PMID:19623244

  5. Myoglobin expression in prostate cancer is correlated to androgen receptor expression and markers of tumor hypoxia.

    PubMed

    Meller, Sebastian; Bicker, Anne; Montani, Matteo; Ikenberg, Kristian; Rostamzadeh, Babak; Sailer, Verena; Wild, Peter; Dietrich, Dimo; Uhl, Barbara; Sulser, Tullio; Moch, Holger; Gorr, Thomas A; Stephan, Carsten; Jung, Klaus; Hankeln, Thomas; Kristiansen, Glen

    2014-10-01

    Recent studies identified unexpected expression and transcriptional complexity of the hemoprotein myoglobin (MB) in human breast cancer but its role in prostate cancer is still unclear. Expression of MB was immunohistochemically analyzed in three independent cohorts of radical prostatectomy specimens (n = 409, n = 625, and n = 237). MB expression data were correlated with clinicopathological parameters and molecular parameters of androgen and hypoxia signaling. Expression levels of novel tumor-associated MB transcript variants and the VEGF gene as a hypoxia marker were analyzed using qRT-PCR. Fifty-three percent of the prostate cancer cases were MB positive and significantly correlated with androgen receptor (AR) expression (p < 0.001). The positive correlation with CAIX (p < 0.001) and FASN (p = 0.008) as well as the paralleled increased expression of the tumor-associated MB transcript variants and VEGF suggest that hypoxia participates in MB expression regulation. Analogous to breast cancer, MB expression in prostate cancer is associated with steroid hormone signaling and markers of hypoxia. Further studies must elucidate the novel functional roles of MB in human carcinomas, which probably extend beyond its classic intramuscular function in oxygen storage. PMID:25172328

  6. Hypoxia-inducible factors in human pulmonary arterial hypertension: a link to the intrinsic myeloid abnormalities.

    PubMed

    Farha, Samar; Asosingh, Kewal; Xu, Weiling; Sharp, Jacqueline; George, Deepa; Comhair, Suzy; Park, Margaret; Tang, W H Wilson; Loyd, James E; Theil, Karl; Tubbs, Raymond; Hsi, Eric; Lichtin, Alan; Erzurum, Serpil C

    2011-03-31

    Pulmonary arterial hypertension (PAH) is a proliferative vasculopathy characterized by high circulating CD34(+)CD133(+) proangiogenic progenitors, and endothelial cells that have pathologic expression of hypoxia-inducible factor 1 α (HIF-1α). Here, CD34(+)CD133(+) progenitor cell numbers are shown to be higher in PAH bone marrow, blood, and pulmonary arteries than in healthy controls. The HIF-inducible myeloid-activating factors erythropoietin, stem cell factor (SCF), and hepatocyte growth factor (HGF) are also present at higher than normal levels in PAH blood, and related to disease severity. Primary endothelial cells harvested from human PAH lungs produce greater HGF and progenitor recruitment factor stromal-derived factor 1 α (SDF-1α) than control lung endothelial cells, and thus may contribute to bone marrow activation. Even though PAH patients had normal numbers of circulating blood elements, hematopoietic alterations in myeloid and erythroid lineages and reticulin fibrosis identified a subclinical myeloproliferative process. Unexpectedly, evaluation of bone marrow progenitors and reticulin in nonaffected family members of patients with familial PAH revealed similar myeloid abnormalities. Altogether, the results show that PAH is linked to myeloid abnormalities, some of which may be related to increased production of HIF-inducible factors by diseased pulmonary vasculature, but findings in nonaffected family suggest myeloid abnormalities may be intrinsic to the disease process. PMID:21258008

  7. Hypoxia-inducible factors in human pulmonary arterial hypertension: a link to the intrinsic myeloid abnormalities

    PubMed Central

    Asosingh, Kewal; Xu, Weiling; Sharp, Jacqueline; George, Deepa; Comhair, Suzy; Park, Margaret; Tang, W. H. Wilson; Loyd, James E.; Theil, Karl; Tubbs, Raymond; Hsi, Eric; Lichtin, Alan

    2011-01-01

    Pulmonary arterial hypertension (PAH) is a proliferative vasculopathy characterized by high circulating CD34+CD133+ proangiogenic progenitors, and endothelial cells that have pathologic expression of hypoxia-inducible factor 1 α (HIF-1α). Here, CD34+CD133+ progenitor cell numbers are shown to be higher in PAH bone marrow, blood, and pulmonary arteries than in healthy controls. The HIF-inducible myeloid-activating factors erythropoietin, stem cell factor (SCF), and hepatocyte growth factor (HGF) are also present at higher than normal levels in PAH blood, and related to disease severity. Primary endothelial cells harvested from human PAH lungs produce greater HGF and progenitor recruitment factor stromal-derived factor 1 α (SDF-1α) than control lung endothelial cells, and thus may contribute to bone marrow activation. Even though PAH patients had normal numbers of circulating blood elements, hematopoietic alterations in myeloid and erythroid lineages and reticulin fibrosis identified a subclinical myeloproliferative process. Unexpectedly, evaluation of bone marrow progenitors and reticulin in nonaffected family members of patients with familial PAH revealed similar myeloid abnormalities. Altogether, the results show that PAH is linked to myeloid abnormalities, some of which may be related to increased production of HIF-inducible factors by diseased pulmonary vasculature, but findings in nonaffected family suggest myeloid abnormalities may be intrinsic to the disease process. PMID:21258008

  8. Social categories as markers of intrinsic interpersonal obligations.

    PubMed

    Rhodes, Marjorie; Chalik, Lisa

    2013-06-01

    Social categorization is an early-developing feature of human social cognition, yet the role that social categories play in children's understanding of and predictions about human behavior has been unclear. In the studies reported here, we tested whether a foundational functional role of social categories is to mark people as intrinsically obligated to one another (e.g., obligated to protect rather than harm). In three studies, children (aged 3-9, N = 124) viewed only within-category harm as violating intrinsic obligations; in contrast, they viewed between-category harm as violating extrinsic obligations defined by explicit rules. These data indicate that children view social categories as marking patterns of intrinsic interpersonal obligations, suggesting that a key function of social categories is to support inferences about how people will relate to members of their own and other groups. PMID:23613213

  9. Intrinsic vascular dopamine – a key modulator of hypoxia-induced vasodilatation in splanchnic vessels

    PubMed Central

    Pfeil, Uwe; Kuncova, Jitka; Brüggmann, Doerthe; Paddenberg, Renate; Rafiq, Amir; Henrich, Michael; Weigand, Markus A; Schlüter, Klaus-Dieter; Mewe, Marco; Middendorff, Ralf; Slavikova, Jana; Kummer, Wolfgang

    2014-01-01

    Dopamine not only is a precursor of the catecholamines noradrenaline and adrenaline but also serves as an independent neurotransmitter and paracrine hormone. It plays an important role in the pathogenesis of hypertension and is a potent vasodilator in many mammalian systemic arteries, strongly suggesting an endogenous source of dopamine in the vascular wall. Here we demonstrated dopamine, noradrenaline and adrenaline in rat aorta and superior mesenteric arteries (SMA) by radioimmunoassay. Chemical sympathectomy with 6-hydroxydopamine showed a significant reduction of noradrenaline and adrenaline, while dopamine levels remained unaffected. Isolated endothelial cells were able to synthesize and release dopamine upon cAMP stimulation. Consistent with these data, mRNAs coding for catecholamine synthesizing enzymes, i.e. tyrosine hydroxylase (TH), aromatic l-amino acid decarboxylase, and dopamine-β-hydroxylase were detected by RT-PCR in cultured endothelial cells from SMA. TH protein was detected by immunohistochemisty and Western blot. Exposure of endothelial cells to hypoxia (1% O2) increased TH mRNA. Vascular smooth muscle cells partially expressed catecholaminergic traits. A physiological role of endogenous vascular dopamine was shown in SMA, where D1 dopamine receptor blockade abrogated hypoxic vasodilatation. Experiments on SMA with endothelial denudation revealed a significant contribution of the endothelium, although subendothelial dopamine release dominated. From these results we conclude that endothelial cells and cells of the underlying vascular wall synthesize and release dopamine in an oxygen-regulated manner. In the splanchnic vasculature, this intrinsic non-neuronal dopamine is the dominating vasodilator released upon lowering of oxygen tension. PMID:24535440

  10. Expression and Prognostic Significance of a Panel of Tissue Hypoxia Markers in Head-and-Neck Squamous Cell Carcinomas

    SciTech Connect

    Le, Quynh-Thu Kong, Christina; Lavori, Phillip W.; O'Byrne, Ken; Erler, Janine T.; Huang Xin; Chen Yijun; Cao Hongbin; Tibshirani, Robert; Denko, Nic; Giaccia, Amato J.; Koong, Albert C.

    2007-09-01

    Purpose: To investigate the expression pattern of hypoxia-induced proteins identified as being involved in malignant progression of head-and-neck squamous cell carcinoma (HNSCC) and to determine their relationship to tumor pO{sub 2} and prognosis. Methods and Materials: We performed immunohistochemical staining of hypoxia-induced proteins (carbonic anhydrase IX [CA IX], BNIP3L, connective tissue growth factor, osteopontin, ephrin A1, hypoxia inducible gene-2, dihydrofolate reductase, galectin-1, I{kappa}B kinase {beta}, and lysyl oxidase) on tumor tissue arrays of 101 HNSCC patients with pretreatment pO{sub 2} measurements. Analysis of variance and Fisher's exact tests were used to evaluate the relationship between marker expression, tumor pO{sub 2}, and CA IX staining. Cox proportional hazard model and log-rank tests were used to determine the relationship between markers and prognosis. Results: Osteopontin expression correlated with tumor pO{sub 2} (Eppendorf measurements) (p = 0.04). However, there was a strong correlation between lysyl oxidase, ephrin A1, and galectin-1 and CA IX staining. These markers also predicted for cancer-specific survival and overall survival on univariate analysis. A hypoxia score of 0-5 was assigned to each patient, on the basis of the presence of strong staining for these markers, whereby a higher score signifies increased marker expression. On multivariate analysis, increasing hypoxia score was an independent prognostic factor for cancer-specific survival (p = 0.015) and was borderline significant for overall survival (p = 0.057) when adjusted for other independent predictors of outcomes (hemoglobin and age). Conclusions: We identified a panel of hypoxia-related tissue markers that correlates with treatment outcomes in HNSCC. Validation of these markers will be needed to determine their utility in identifying patients for hypoxia-targeted therapy.

  11. The tumour hypoxia marker pimonidazole reflects a transcriptional programme associated with aggressive prostate cancer

    PubMed Central

    Ragnum, H B; Vlatkovic, L; Lie, A K; Axcrona, K; Julin, C H; Frikstad, K M; Hole, K H; Seierstad, T; Lyng, H

    2015-01-01

    Background: The hypoxia marker pimonidazole is a candidate biomarker of cancer aggressiveness. We investigated the transcriptional programme associated with pimonidazole staining in prostate cancer. Methods: Index tumour biopsies were taken by image guidance from an investigation cohort of 52 patients, where 43 patients received pimonidazole before prostatectomy. Biopsy location within the index tumour was verified for 46 (88%) patients, who were included for gene expression profiling and immunohistochemistry. Two independent cohorts of 59 and 281 patients were used for validation. Results: Expression of genes in proliferation, DNA repair and hypoxia response was a major part of the transcriptional programme associated with pimonidazole staining. A signature of 32 essential genes was constructed and showed positive correlation to Ki67 staining, confirming the increased proliferation in hypoxic tumours as suggested from the gene data. Positive correlations were also found to tumour stage and lymph node status, but not to blood prostate-specific antigen level, consistent with the findings for pimonidazole staining. The association with aggressiveness was confirmed in validation cohorts, where the signature correlated with Gleason score and had independent prognostic impact, respectively. Conclusions: Pimonidazole staining reflects an aggressive hypoxic phenotype of prostate cancer characterised by upregulation of proliferation, DNA repair and hypoxia response genes. PMID:25461803

  12. Radiosynthesis of [131I]IAZGP via nucleophilic substitution and its biological evaluation as a hypoxia marker — is specific activity a factor influencing hypoxia-mapping ability of a hypoxia marker?

    PubMed Central

    Suehiro, Makiko; Burgman, Paul; Carlin, Sean; Burke, Sean; Yang, Guangbin; Ouerfelli, Ouathek; Oehler-Janne, Christoph; O’Donoghue, Joseph; Ling, Clifton; Humm, John

    2010-01-01

    Introduction The hypoxia marker IAZGP, 1-(6-deoxy-6-iodo-β-D-galactopyranosyl)-2-nitroimidazole, has been labeled with 123I/124I/125I/131I via iodine–radioiodine exchange, which gives the radiotracer in a specific activity of 10–90 MBq/μmol. We synthesized the same radiotracer possessing several hundred to thousand times higher specific activity (high-SA IAZGP) via nucleophilic substitution and compared its biological behavior with that of conventionally produced IAZGP (low-SA IAZGP) to determine if specific activity is a factor influencing cell uptake kinetics, biodistribution and intratumor microregional localization of the radiotracer. Methods High-SA [131I]IAZGP was prepared by substitution of the tosyl functionality with [131I]iodide. In vitro uptake of high- and low-SA [131I]IAZGP by HCT8 and HT29 cells was assessed in normoxic and hypoxic conditions. Biodistribution and intratumor localization of high- and low-SA [131I]IAZGP were determined by injection into HT29 tumor-bearing mice. Results The nucleophilic substitution reaction proceeded efficiently in acetonitrile at 150°C, giving the final product in an average yield of 42% and an average specific activity of 30 GBq/μmol. In vitro, high-SA [131I]IAZGP was incorporated into the tumor cells with similar kinetics and oxygen dependence to low-SA [131I]IAZGP. In HT29 tumor-bearing mice, biodistributions of high- and low-SA [131I]IAZGP were equivalent. Ex vivo autoradiography revealed heterogeneous intratumor localization of high-SA [131I]IAZGP corresponding closely to distributions of other exogenous and endogenous hypoxia markers. Comparable microregional distribution patterns were observed with low-SA [131I]IAZGP. Conclusions Radiolabeled IAZGP produced via nucleophilic substitution is validated as an exogenous hypoxia marker. Specific activity does not appear to influence the in vivo hypoxia-mapping ability of the radiotracer. PMID:19520288

  13. No oxygen? No problem! Intrinsic brain tolerance to hypoxia in vertebrates

    PubMed Central

    Larson, John; Drew, Kelly L.; Folkow, Lars P.; Milton, Sarah L.; Park, Thomas J.

    2014-01-01

    Many vertebrates are challenged by either chronic or acute episodes of low oxygen availability in their natural environments. Brain function is especially vulnerable to the effects of hypoxia and can be irreversibly impaired by even brief periods of low oxygen supply. This review describes recent research on physiological mechanisms that have evolved in certain vertebrate species to cope with brain hypoxia. Four model systems are considered: freshwater turtles that can survive for months trapped in frozen-over lakes, arctic ground squirrels that respire at extremely low rates during winter hibernation, seals and whales that undertake breath-hold dives lasting minutes to hours, and naked mole-rats that live in crowded burrows completely underground for their entire lives. These species exhibit remarkable specializations of brain physiology that adapt them for acute or chronic episodes of hypoxia. These specializations may be reactive in nature, involving modifications to the catastrophic sequelae of oxygen deprivation that occur in non-tolerant species, or preparatory in nature, preventing the activation of those sequelae altogether. Better understanding of the mechanisms used by these hypoxia-tolerant vertebrates will increase appreciation of how nervous systems are adapted for life in specific ecological niches as well as inform advances in therapy for neurological conditions such as stroke and epilepsy. PMID:24671961

  14. No oxygen? No problem! Intrinsic brain tolerance to hypoxia in vertebrates.

    PubMed

    Larson, John; Drew, Kelly L; Folkow, Lars P; Milton, Sarah L; Park, Thomas J

    2014-04-01

    Many vertebrates are challenged by either chronic or acute episodes of low oxygen availability in their natural environments. Brain function is especially vulnerable to the effects of hypoxia and can be irreversibly impaired by even brief periods of low oxygen supply. This review describes recent research on physiological mechanisms that have evolved in certain vertebrate species to cope with brain hypoxia. Four model systems are considered: freshwater turtles that can survive for months trapped in frozen-over lakes, arctic ground squirrels that respire at extremely low rates during winter hibernation, seals and whales that undertake breath-hold dives lasting minutes to hours, and naked mole-rats that live in crowded burrows completely underground for their entire lives. These species exhibit remarkable specializations of brain physiology that adapt them for acute or chronic episodes of hypoxia. These specializations may be reactive in nature, involving modifications to the catastrophic sequelae of oxygen deprivation that occur in non-tolerant species, or preparatory in nature, preventing the activation of those sequelae altogether. Better understanding of the mechanisms used by these hypoxia-tolerant vertebrates will increase appreciation of how nervous systems are adapted for life in specific ecological niches as well as inform advances in therapy for neurological conditions such as stroke and epilepsy. PMID:24671961

  15. Hypoxia inducible BHLHB2 is a novel and independent prognostic marker in pancreatic ductal adenocarcinoma

    SciTech Connect

    Wang, Weibin; Reiser-Erkan, Carolin; Michalski, Christoph W.; Raggi, Matthias C.; Quan, Liao; Yupei, Zhao; Friess, Helmut; Erkan, Mert; Kleeff, Joerg

    2010-10-22

    cells. Patients with weak/absent nuclear BHLHB2 staining had significantly worse median survival compared to those with strong staining (13 months vs. 27 months, p = 0.03). In a multivariable analysis, BHLHB2 staining was an independent prognostic factor (Hazard-Ratio = 2.348, 95% CI = 1.250-4.411, p = 0.008). Conclusions: Hypoxia-inducible BHLHB2 expression is a novel independent prognostic marker in pancreatic cancer patients and indicates increased chemosensitivity towards gemcitabine.

  16. FDG uptake, a surrogate of tumour hypoxia?

    PubMed Central

    Van de Wiele, Christophe

    2008-01-01

    Introduction Tumour hyperglycolysis is driven by activation of hypoxia-inducible factor-1 (HIF-1) through tumour hypoxia. Accordingly, the degree of 2-fluro-2-deoxy-d-glucose (FDG) uptake by tumours might indirectly reflect the level of hypoxia, obviating the need for more specific radiopharmaceuticals for hypoxia imaging. Discussion In this paper, available data on the relationship between hypoxia and FDG uptake by tumour tissue in vitro and in vivo are reviewed. In pre-clinical in vitro studies, acute hypoxia was consistently shown to increase FDG uptake by normal and tumour cells within a couple of hours after onset with mobilisation or modification of glucose transporters optimising glucose uptake, followed by a delayed response with increased rates of transcription of GLUT mRNA. In pre-clinical imaging studies on chronic hypoxia that compared FDG uptake by tumours grown in rat or mice to uptake by FMISO, the pattern of normoxic and hypoxic regions within the human tumour xenografts, as imaged by FMISO, largely correlated with glucose metabolism although minor locoregional differences could not be excluded. In the clinical setting, data are limited and discordant. Conclusion Further evaluation of FDG uptake by various tumour types in relation to intrinsic and bioreductive markers of hypoxia and response to radiotherapy or hypoxia-dependent drugs is needed to fully assess its application as a marker of hypoxia in the clinical setting. PMID:18509637

  17. Nitroimidazole adducts as markers for tissue hypoxia: mechanistic studies in aerobic normal tissues and tumour cells.

    PubMed Central

    Parliament, M. B.; Wiebe, L. I.; Franko, A. J.

    1992-01-01

    Two aspects of the aerobic metabolism of nitroimidazole markers for hypoxia were investigated. Several normal murine tissues which are likely to be well oxygenated bind misonidazole at rates comparable to those of hypoxic regions in tumours. The possibility that this aerobic activation occurs via an oxygen independent process such as an initial two electron reduction was studied. Binding to the oesophageal mucosa of mice which occurred under hypoxia in vitro was inhibited by at least 95% in the presence of 10% oxygen. Dicoumarol, an inhibitor of DT-diaphorase, was shown to cause only small reductions in misonidazole binding to oesophageal epithelium and smooth muscle in vitro and to EMT6 tumours, liver, oesophageal and tracheal epithelium, parotid gland and smooth muscle in vivo. Thus an oxygen-insensitive process is not a major cause of the high binding rate in oesophageal mucosa, and may not contribute significantly to the observed binding in other normal tissues. It has been suggested that metabolism of nitroimidazoles by aerobic cells in tumours might be sufficient to minimise access of these compounds to hypoxic regions, particularly at the micromolar concentrations currently in use clinically. The uptake of 125I-iodoazomycin arabinoside by RIF-1 and EMT6 tumours was found to be directly proportional to injected dose over concentrations between 0.5 and 50 microM. Labelling of hypoxic regions in EMT6 tumours by high specific activity 3H-misonidazole at 1 microM was found to be similar to that obtained at 50 microM. Images Figure 1 PMID:1280990

  18. Characterization of carbonic anhydrase IX (CA IX) as an endogenous marker of chronic hypoxia in live human tumor cells

    SciTech Connect

    Vordermark, Dirk . E-mail: vordermark_d@klinik.uni-wuerzburg.de; Kaffer, Anja; Riedl, Susanne; Katzer, Astrid; Flentje, Michael

    2005-03-15

    Purpose: Published clinical studies provide conflicting data regarding the prognostic significance of carbonic anhydrase IX (CA IX) overexpression as an endogenous marker of tumor hypoxia and its comparability with other methods of hypoxia detection. We performed a systematic analysis of CA IX protein levels under various in vitro conditions of tumor hypoxia in HT 1080 human fibrosarcoma and FaDu human pharyngeal carcinoma cells. Because sorting of live CA IX positive cells from tumors provides a tool to study the radiosensitivity of chronically hypoxic cells, we modified and tested a CA IX flow cytometry protocol on mixed hypoxic/aerobic suspensions of HT 1080 and FaDu cells. Methods and materials: HT 1080 and FaDu cells were treated with up to 24 h of in vitro hypoxia and up to 96 h of reoxygenation. To test the effect of nonhypoxic stimuli, glucose and serum availability, pH and cell density were modified. CA IX protein was quantified in Western blots of whole-cell lysates. Mixed suspensions with known percentages of hypoxic cells were prepared for CA IX flow cytometry. The same mixtures were assayed for clonogenic survival after 10 Gy. Results: Hypoxia-induced CA IX protein expression was seen after >6 h at {<=}5% O{sub 2}, and protein was stable over 96 h of reoxygenation in both cell lines. Glucose deprivation abolished the hypoxic CA IX response, and high cell density caused CA IX induction under aerobic conditions. Measured percentages of CA IX-positive cells in mixtures closely reflected known percentages of hypoxic cells in HT 1080 and were associated with radioresistance of mixtures after 10 Gy. Conclusion: CA IX is a stable marker of current or previous chronic hypoxia but influenced by nonhypoxic stimuli. Except the time course of accumulation, all properties of this marker resembled our previous findings for hypoxia-inducible factor-1{alpha}. A modified flow cytometry protocol provided good separability of CA IX-negative and -positive cells in vitro

  19. A comparison of oral and intravenous pimonidazole in canine tumors using intravenous CCI-103F as a control hypoxia marker

    SciTech Connect

    Kleiter, Miriam M.; Thrall, Donald E.; Malarkey, David E.; Ji Xiaoshen; Lee, David Y.W.; Chou, S.-C.; Raleigh, James A. . E-mail: james_raleigh@med.unc.edu

    2006-02-01

    Purpose: Pimonidazole HCl is widely used in immunohistochemical analyses of hypoxia in normal and malignant tissues. The present study investigates oral administration as a means of minimizing invasiveness. Methods and Materials: Twelve dogs with confirmed malignancy received 0.5 g/m{sup 2} of pimonidazole HCl: 6 by mouth and 6 by i.v. infusion. All dogs received i.v. CCI-103F as a control. Plasma levels of pimonidazole, pimonidazole N-oxide, and CCI-103F were measured. Tumor biopsies were formalin fixed, paraffin embedded, sectioned, immunostained, and analyzed for pimonidazole and CCI-103F binding. pH dependence for pimonidazole and CCI-103F binding was studied in vitro. Results: Pimonidazole and CCI-103F binding in carcinomas and sarcomas was strongly correlated for both oral and i.v. pimonidazole HCl (r {sup 2} = 0.97). On average, the extent of pimonidazole binding exceeded that for CCI-103F by a factor of approximately 1.2, with the factor ranging from 1.0 to 1.65. Binding of both markers was pH dependent, but pimonidazole binding was greater at all values of pH. Conclusions: Oral pimonidazole HCl is effective as a hypoxia marker in spontaneously arising canine tumors. Selective cellular uptake and concomitant higher levels of binding in regions of hypoxia at the high end of pH gradients might account for the greater extent of pimonidazole binding.

  20. Proteomic Identification of Novel Differentiation Plasma Protein Markers in Hypobaric Hypoxia-Induced Rat Model

    PubMed Central

    Ahmad, Mohammad Faiz; Sharma, Manish; Garg, Iti; Bhargava, Kalpana

    2014-01-01

    Background Hypobaric hypoxia causes complex changes in the expression of genes, including stress related genes and corresponding proteins that are necessary to maintain homeostasis. Whereas most prior studies focused on single proteins, newer methods allowing the simultaneous study of many proteins could lead to a better understanding of complex and dynamic changes that occur during the hypobaric hypoxia. Methods In this study we investigated the temporal plasma protein alterations of rat induced by hypobaric hypoxia at a simulated altitude of 7620 m (25,000 ft, 282 mm Hg) in a hypobaric chamber. Total plasma proteins collected at different time points (0, 6, 12 and 24 h), separated by two-dimensional electrophoresis (2-DE) and identified using matrix assisted laser desorption ionization time of flight (MALDI-TOF/TOF). Biological processes that were enriched in the plasma proteins during hypobaric hypoxia were identified using Gene Ontology (GO) analysis. According to their properties and obvious alterations during hypobaric hypoxia, changes of plasma concentrations of Ttr, Prdx-2, Gpx -3, Apo A-I, Hp, Apo-E, Fetub and Nme were selected to be validated by Western blot analysis. Results Bioinformatics analysis of 25 differentially expressed proteins showed that 23 had corresponding candidates in the database. The expression patterns of the eight selected proteins observed by Western blot were in agreement with 2-DE results, thus confirming the reliability of the proteomic analysis. Most of the proteins identified are related to cellular defense mechanisms involving anti-inflammatory and antioxidant activity. Their presence reflects the consequence of serial cascades initiated by hypobaric hypoxia. Conclusion/Significance This study provides information about the plasma proteome changes induced in response to hypobaric hypoxia and thus identification of the candidate proteins which can act as novel biomarkers. PMID:24842778

  1. Chondroitin Sulfate Proteoglycan CSPG4 as a Novel Hypoxia-Sensitive Marker in Pancreatic Tumors

    PubMed Central

    Keleg, Shereen; Titov, Alexandr; Heller, Anette; Giese, Thomas; Tjaden, Christine; Ahmad, Sufian S.; Gaida, Matthias M.; Bauer, Andrea S.; Werner, Jens; Giese, Nathalia A.

    2014-01-01

    CSPG4 marks pericytes, undifferentiated precursors and tumor cells. We assessed whether the shed ectodomain of CSPG4 (sCSPG4) might circulate and reflect potential changes in CSPG4 tissue expression (pCSPG4) due to desmoplastic and malignant aberrations occurring in pancreatic tumors. Serum sCSPG4 was measured using ELISA in test (n = 83) and validation (n = 221) cohorts comprising donors (n = 11+26) and patients with chronic pancreatitis (n = 11+20) or neoplasms: benign (serous cystadenoma SCA, n = 13+20), premalignant (intraductal dysplastic IPMNs, n = 9+55), and malignant (IPMN-associated invasive carcinomas, n = 4+14; ductal adenocarcinomas, n = 35+86). Pancreatic pCSPG4 expression was evaluated using qRT-PCR (n = 139), western blot analysis and immunohistochemistry. sCSPG4 was found in circulation, but its level was significantly lower in pancreatic patients than in donors. Selective maintenance was observed in advanced IPMNs and PDACs and showed a nodal association while lacking prognostic relevance. Pancreatic pCSPG4 expression was preserved or elevated, whereby neoplastic cells lacked pCSPG4 or tended to overexpress without shedding. Extreme pancreatic overexpression, membranous exposure and tissuehigh/seralow-discordance highlighted stroma-poor benign cystic neoplasm. SCA is known to display hypoxic markers and coincide with von-Hippel-Lindau and Peutz-Jeghers syndromes, in which pVHL and LBK1 mutations affect hypoxic signaling pathways. In vitro testing confined pCSPG4 overexpression to normal mesenchymal but not epithelial cells, and a third of tested carcinoma cell lines; however, only the latter showed pCSPG4-responsiveness to chronic hypoxia. siRNA-based knockdowns failed to reduce the malignant potential of either normoxic or hypoxic cells. Thus, overexpression of the newly established conditional hypoxic indicator, CSPG4, is apparently non-pathogenic in pancreatic malignancies but might mark distinct epithelial

  2. Irradiation-Dependent Effects on Tumor Perfusion and Endogenous and Exogenous Hypoxia Markers in an A549 Xenograft Model

    SciTech Connect

    Fokas, Emmanouil; Haenze, Joerg; Kamlah, Florentine; Eul, Bastian G.; Lang, Nico; Keil, Boris; Heverhagen, Johannes T.; Engenhart-Cabillic, Rita; An Hanxiang; Rose, Frank

    2010-08-01

    Purpose: Hypoxia is a major determinant of tumor radiosensitivity, and microenvironmental changes in response to ionizing radiation (IR) are often heterogenous. We analyzed IR-dependent changes in hypoxia and perfusion in A549 human lung adenocarcinoma xenografts. Materials and Methods: Immunohistological analysis of two exogenously added chemical hypoxic markers, pimonidazole and CCI-103F, and of the endogenous marker Glut-1 was performed time dependently after IR. Tumor vessels and apoptosis were analyzed using CD31 and caspase-3 antibodies. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and fluorescent beads (Hoechst 33342) were used to monitor vascular perfusion. Results: CCI-103F signals measuring the fraction of hypoxic areas after IR were significantly decreased by approximately 50% when compared with pimonidazole signals, representing the fraction of hypoxic areas from the same tumors before IR. Interestingly, Glut-1 signals were significantly decreased at early time point (6.5 h) after IR returning to the initial levels at 30.5 h. Vascular density showed no difference between irradiated and control groups, whereas apoptosis was significantly induced at 10.5 h post-IR. DCE-MRI indicated increased perfusion 1 h post-IR. Conclusions: The discrepancy between the hypoxic fractions of CCI-103F and Glut-1 forces us to consider the possibility that both markers reflect different metabolic alterations of tumor microenvironment. The reliability of endogenous markers such as Glut-1 to measure reoxygenation in irradiated tumors needs further consideration. Monitoring tumor microvascular response to IR by DCE-MRI and measuring tumor volume alterations should be encouraged.

  3. Heterochromatin Protein 1 Binding Protein 3 Expression as a Candidate Marker of Intrinsic 5-Fluorouracil Resistance

    PubMed Central

    HADAC, JAMIE N.; MILLER, DEVON D.; GRIMES, IAN C.; CLIPSON, LINDA; NEWTON, MICHAEL A.; SCHELMAN, WILLIAM R.; HALBERG, RICHARD B.

    2016-01-01

    Background Despite receiving post-operative 5-fluorouracil (5-FU)-based chemotherapy, approximately 50% of patients with stage IIIC colon cancer experience recurrence. Currently, no molecular signature can predict response to 5-FU. Materials and Methods Mouse models of colon cancer have been developed and characterized. Individual tumors in these mice can be longitudinally monitored and assessed to identify differences between those that are responsive and those that are resistant to therapy. Gene expression was analyzed in serial biopsies that were collected before and after treatment with 5-FU. Colon tumors had heterogeneous responses to treatment with 5-FU. Microarray analysis of pretreatment biopsies revealed that Hp1bp3, a gene encoding heterochromatin protein 1 binding protein 3, was differentially expressed between sensitive and resistant tumors. Conclusion Using mouse models of human colorectal cancer, Hp1bp3 was identified as a candidate marker of intrinsic 5-FU resistance and may represent a potential biomarker for patient stratification or a target of clinical importance. PMID:26976970

  4. Lycopene Enriched Tomato Extract Inhibits Hypoxia, Angiogenesis, and Metastatic Markers in early Stage N-Nitrosodiethylamine Induced Hepatocellular Carcinoma.

    PubMed

    Bhatia, Nisha; Gupta, Prachi; Singh, Baljinder; Koul, Ashwani

    2015-01-01

    Targeting altered pathways during initial stage of hepatocellular carcinoma (HCC) development is viewed as an effective and promising strategy to control this disease. Present study investigated the potential effect of lycopene-enriched tomato extract (LycT) on hypoxia-induced factor (HIF)-1α, HOX, VEGF, CD31, matrix metalloproteinase (MMP)-2, MMP-9, and alpha fetoprotein (AFP)expression during initial stages of N-nitrosodiethylamine (NDEA) induced HCC. Female Balb/c mice (8-10 wk) were assigned to 4 groups: control, NDEA (200 mg NDEA i.p./kg body weight, cumulative), LycT (5 mg lycopene orally/kg body weight; 3 times a week), and LycT + NDEA. LycT treatment began 2 wk before NDEA administration and continued until the end of the 10 wk study. The onset of HCC by NDEA was associated with significant alteration in serum biochemical markers [alanine transaminases (ALT), aspartate transaminases (AST), and alkaline phosphatases (ALP), lactate dehydrogenase (LDH), urea, A/G ratio, and bilirubin] and in liver histopathology. LycT treatment significantly reduced the levels of these markers. LycT treatment to NDEA mice also led to significant reduction in protein levels of AFP, HIF-1α, VEGF, CD31, MMP-2, and MMP-9 in comparison with NDEA group alone. These parameters are important biomarkers of hypoxia, angiogenesis, and metastasis, which reflect the advanced disease stage. The study provides evidence that prophylactic dietary supplementation with LycT may counteract HCC progression and/or protect against disease onset. PMID:26474105

  5. An enzyme-linked immunosorbent assay for hypoxia marker binding in tumours.

    PubMed Central

    Raleigh, J. A.; La Dine, J. K.; Cline, J. M.; Thrall, D. E.

    1994-01-01

    An enzyme-linked immunosorbent assay (ELISA) has been developed for measuring the in vivo binding of a hexafluorinated 2-nitroimidazole (CCI-103F) in tumour tissue biopsies. The binding of CCI-103F is believed to reflect the presence of hypoxia in tumours. The ELISA provides a sensitive and convenient method of measuring CCI-103F binding which does not require the injection of radioactive reagents. The ELISA is based on reagents prepared from synthetic antigens formed by the reductive activation and binding of CCI-103F to proteins in novel test tube experiments. Calibration of the ELISA involved comparing the ELISA with the radioactivity contained either in protein-CCI-103F adducts formed in vitro with tritiated CCI-103F or in tissues isolated from a tumour-bearing dog which had been injected with tritium-labelled CCI-103F. The two approaches to calibration are compared. The scope and limitation of the ELISA for measuring the binding of CCI-103F is discussed and an example of the application of the ELISA to measuring changes in tumour hypoxia in canine patients undergoing fractionated radiation therapy is presented. Images Figure 3 PMID:8286212

  6. Intrinsic hepatocyte dedifferentiation is accompanied by upregulation of mesenchymal markers, protein sialylation and core alpha 1,6 linked fucosylation.

    PubMed

    Mehta, Anand; Comunale, Mary Ann; Rawat, Siddhartha; Casciano, Jessica C; Lamontagne, Jason; Herrera, Harmin; Ramanathan, Aarti; Betesh, Lucy; Wang, Mengjun; Norton, Pamela; Steel, Laura F; Bouchard, Michael J

    2016-01-01

    Alterations in N-linked glycosylation have long been associated with cancer but for the most part, the reasons why have remained poorly understood. Here we show that increased core fucosylation is associated with de-differentiation of primary hepatocytes and with the appearance of markers indicative of a transition of cells from an epithelial to a mesenchymal state. This increase in core fucosylation was associated with increased levels of two enzymes involved in α-1,6 linked fucosylation, GDP-mannose 4, 6-dehydratase (Gmds) and to a lesser extent fucosyltransferase 8 (Fut8). In addition, the activation of cancer-associated cellular signaling pathways in primary rat hepatocytes can increase core fucosylation and induce additional glycoform alterations on hepatocyte proteins. Specifically, we show that increased levels of protein sialylation and α-1,6-linked core fucosylation are observed following activation of the β-catenin pathway. Activation of the Akt signaling pathway or induction of hypoxia also results in increased levels of fucosylation and sialylation. We believe that this knowledge will help in the better understanding of the genetic factors associated with altered glycosylation and may allow for the development of more clinically relevant biomarkers. PMID:27328854

  7. Intrinsic hepatocyte dedifferentiation is accompanied by upregulation of mesenchymal markers, protein sialylation and core alpha 1,6 linked fucosylation

    PubMed Central

    Mehta, Anand; Comunale, Mary Ann; Rawat, Siddhartha; Casciano, Jessica C.; Lamontagne, Jason; Herrera, Harmin; Ramanathan, Aarti; Betesh, Lucy; Wang, Mengjun; Norton, Pamela; Steel, Laura F.; Bouchard, Michael J.

    2016-01-01

    Alterations in N-linked glycosylation have long been associated with cancer but for the most part, the reasons why have remained poorly understood. Here we show that increased core fucosylation is associated with de-differentiation of primary hepatocytes and with the appearance of markers indicative of a transition of cells from an epithelial to a mesenchymal state. This increase in core fucosylation was associated with increased levels of two enzymes involved in α-1,6 linked fucosylation, GDP-mannose 4, 6-dehydratase (Gmds) and to a lesser extent fucosyltransferase 8 (Fut8). In addition, the activation of cancer-associated cellular signaling pathways in primary rat hepatocytes can increase core fucosylation and induce additional glycoform alterations on hepatocyte proteins. Specifically, we show that increased levels of protein sialylation and α-1,6-linked core fucosylation are observed following activation of the β-catenin pathway. Activation of the Akt signaling pathway or induction of hypoxia also results in increased levels of fucosylation and sialylation. We believe that this knowledge will help in the better understanding of the genetic factors associated with altered glycosylation and may allow for the development of more clinically relevant biomarkers. PMID:27328854

  8. Towards intrinsic graphene biosensor: A label-free, suspended single crystalline graphene sensor for multiplex lung cancer tumor markers detection.

    PubMed

    Li, Peng; Zhang, Bo; Cui, Tianhong

    2015-10-15

    Graphene biosensors reported so far are based on polycrystalline graphene flakes which are anchored on supporting substrates. The influence of grain boundary and the scattering from substrate drastically degrade the properties of graphene and conceal the performance of intrinsic graphene as a sensor. Here we report a label-free biosensor based on suspended single crystalline graphene (SCG), which can get rid of grain boundary and substrate scattering, revealing the biosensing mechanism of intrinsic graphene for the first time. Monolayer SCG flakes were derived from low pressure chemical vapor deposition (LPCVD) method. Multiplex detection of three different lung cancer tumor markers was realized. The suspended structure can largely improve the sensitivity and detection limit (0.1 pg/ml) of the sensor, and the single crystalline nature of SCG enable the biosensor to have superior uniformity compared to polycrystalline ones. The SCG sensors exhibit superb specificity and large linear detection range from 1 pg/ml to 1 μg/ml, showing the prominent advantages of graphene as a sensing material. PMID:25982724

  9. Cerebral Hypoxia

    MedlinePlus

    ... Enhancing Diversity Find People About NINDS NINDS Cerebral Hypoxia Information Page Synonym(s): Hypoxia, Anoxia Table of Contents ( ... Trials Organizations Publicaciones en Español What is Cerebral Hypoxia? Cerebral hypoxia refers to a condition in which ...

  10. Food intake during the previous 24 h as a percentage of usual intake: a marker of hypoxia in infants with bronchiolitis: an observational, prospective, multicenter study

    PubMed Central

    2013-01-01

    Background Hypoxia associated with bronchiolitis is not always easy to assess on clinical grounds alone. The aim of this study was to determine the value of food intake during the previous 24 hours (bottle and spoon feeding), as a percentage of usual intake (24h FI), as a marker of hypoxia, and to compare its diagnostic value with that of usual clinical signs. Methods In this observational, prospective, multicenter study, 18 community pediatricians, enrolled 171 infants, aged from 0 to 6 months, with bronchiolitis (rhinorrhea + dyspnea + cough + expiratory sounds). Infants with risk factors (history of prematurity, chronic heart or lung disorders), breast-fed infants, and infants having previously been treated for bronchial disorders were excluded. The 24h FI, subcostal, intercostal, supracostal retractions, nasal flaring, respiratory rate, pauses, cyanosis, rectal temperature and respiratory syncytial virus test results were noted. The highest stable value of transcutaneous oxygen saturation (SpO2) was recorded. Hypoxia was noted if SpO2 was below 95% and verified. Results 24h FI ≥ 50% was associated with a 96% likelihood of SpO2 ≥ 95% [95% CI, 91–99]. In univariate analysis, 24h FI < 50% had the highest odds ratio (13.8) for SpO2 < 95%, compared to other 24h FI values and other clinical signs, as well as providing one of the best compromises between specificity (90%) and sensitivity (60%) for identifying infants with hypoxia. In multivariate analysis with adjustment for age, SpO2 < 95% was related to the presence of intercostal retractions (OR = 9.1 [95% CI, 2.4-33.8%]) and 24h FI < 50% (OR = 10.9 [95% CI, 3.0-39.1%]). Hospitalization (17 infants) was strongly related to younger age, 24h FI and intercostal retractions. Conclusion In practice, the measure of 24 h FI may be useful in identifying hypoxia and deserves further study. PMID:23311899

  11. Maternal separation prior to neonatal hypoxia-ischemia: Impact on emotional aspects of behavior and markers of synaptic plasticity in hippocampus.

    PubMed

    Markostamou, Ioanna; Ioannidis, Anestis; Dandi, Evgenia; Mandyla, Maria-Aikaterini; Nousiopoulou, Evangelia; Simeonidou, Constantina; Spandou, Evangelia; Tata, Despina A

    2016-08-01

    Exposure to early-life stress is associated with long-term alterations in brain and behavior, and may aggravate the outcome of neurological insults. This study aimed at investigating the possible interaction between maternal separation, a model of early stress, and subsequent neonatal hypoxia-ischemia on emotional behavior and markers of synaptic plasticity in hippocampus. Therefore, rat pups (N=60) were maternally separated for a prolonged (MS 180min) or a brief (MS 15min) period during the first six postnatal days, while a control group was left undisturbed. Hypoxia-ischemia was applied to a subgroup of each rearing condition on postnatal day 7. Emotional behavior was examined at three months of age and included assessments of anxiety (elevated plus maze), depression-like behavior (forced swimming) and spontaneous exploration (open field). Synaptic plasticity was evaluated based on BDNF and synaptophysin expression in CA3 and dentate gyrus hippocampal regions. We found that neonatal hypoxia-ischemia caused increased levels of anxiety, depression-like behavior and locomotor activity (ambulation). Higher anxiety levels were also seen in maternally separated rats (MS180min) compared to non-maternally separated rats, but prolonged maternal separation prior to HI did not potentiate the HI-associated effect. No differences among the three rearing conditions were found regarding depression-like behavior or ambulation. Immunohistochemical evaluation of synaptophysin revealed that both prolonged maternal separation (MS180min) and neonatal hypoxia-ischemia significantly reduced its expression in the CA3 and dentate gyrus. Decreases in synaptophysin expression in these areas were not exacerbated in rats that were maternally separated for a prolonged period prior to HI. Regarding BDNF expression, we found a significant decrease in immunoreactivity only in the hypoxic-ischemic rats that were subjected to the prolonged maternal separation paradigm. The above findings suggest

  12. Inhibition of hypoxia inducible factor-1α downregulates the expression of epithelial to mesenchymal transition early marker proteins without undermining cell survival in hypoxic lens epithelial cells

    PubMed Central

    Neelam, Sudha; Brooks, Morgan M.

    2015-01-01

    Purpose The purpose of this study was to identify potential therapeutic strategies to slow down or prevent the expression of early-onset epithelial to mesenchymal transition (EMT) marker proteins (fibronectin and alpha smooth muscle actin, α-SMA) without sacrificing the synthesis and accumulation of the prosurvival protein vascular endothelial growth factor (VEGF) in cultured virally transformed human lens epithelial (HLE) cells. Methods HLE-B3 cells, maintained in a continuous hypoxic environment (1% oxygen), were treated with SB216763, a specific inhibitor of glycogen synthase kinase-3β (GSK-3β) catalytic activity. Western blot analysis was employed to detect the cytoplasmic and nuclear levels of β-catenin, as well as the total lysate content of fibronectin and α-SMA. Enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of VEGF in cell culture medium. A hypoxia-inducible factor-1α (HIF-1α) translation inhibitor and an HIF-2α translation inhibitor were independently employed to evaluate the effect of hypoxia inducible factor inhibition on EMT marker protein and VEGF expression. XAV932 was used to assess the suppression of nuclear β-catenin and its downstream effect on EMT marker proteins and VEGF expression. Results SB216763-treated HLE-B3 cells caused marked inhibition of GSK-3β activity prompting a significant increase in the translocation of cytoplasmic β-catenin to the nucleus. The enhancement of nuclear β-catenin looked as if it positively correlated with a significant increase in the basal expression of VEGF as well as increased expression of fibronectin and α-SMA. In conjunction with SB216763, coadministration of an HIF-1α translation inhibitor, but not an HIF-2α translation inhibitor, markedly suppressed the expression of fibronectin and α-SMA without affecting VEGF levels. Treatment with XAV932 significantly reduced the level of nuclear β-catenin, but the levels of neither the EMT marker proteins nor VEGF were changed

  13. Comparison of the Hypoxia PET Tracer 18F-EF5 to Immunohistochemical Marker EF5 in 3 Different Human Tumor Xenograft Models

    PubMed Central

    Chitneni, Satish K.; Bida, Gerald T.; Zalutsky, Michael R.; Dewhirst, Mark W.

    2014-01-01

    The availability of 18F-labeled and unlabeled 2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)-acetamide (EF5) allows for a comparative assessment of tumor hypoxia by PET and immunohistochemistry; however, the combined use of these 2 approaches has not been fully assessed in vivo. The aim of this study was to evaluate 18F-EF5 tumor uptake versus EF5 binding and hypoxia as determined from immunohistochemistry at both macroscopic and microregional levels. Methods Three tumor models— PC3, HCT116, and H460—were evaluated. Tumor-bearing animals were coinjected with 18F-EF5 and EF5 (30 mg/kg), and PET imaging was performed at 2.5 h after injection. After PET imaging and 2 min after Hoechst 33342 injection, the tumors were excised and evaluated for 18F-EF5 distribution by autoradiography and EF5 binding by immunohistochemistry. Additionally, the effects of nonradioactive EF5 (30 mg/kg) on the hypoxia-imaging characteristics of 18F-EF5 were evaluated by comparing the PET data for H460 tumors with those from animals injected with 18F-EF5 alone. Results The uptake of 18F-EF5 in hypoxic tumor regions and the spatial relationship between 18F-EF5 uptake and EF5 binding varied among tumors. H460 tumors showed higher tumor-to-muscle contrast in PET imaging; however, the distribution and uptake of the tracer was less specific for hypoxia in H460 than in HCT116 and PC3 tumors. Correlation analyses revealed that the highest spatial correlation between 18F-EF5 uptake and EF5 binding was in PC3 tumors (r = 0.73 ± 0.02) followed by HCT116 (r = 0.60 ± 0.06) and H460 (r = 0.53 ± 0.10). Uptake and binding of 18F-EF5 and EF5 correlated negatively with Hoechst 33342 perfusion marker distribution in the 3 tumor models. Image contrast and heterogeneous uptake of 18F-EF5 in H460 tumors was significantly higher when the radiotracer was used alone versus in combination with unlabeled EF5 (tumor-to-muscle ratio of 2.51 ± 0.33 vs. 1.71 ± 0.17, P , 0.001). Conclusion The uptake

  14. Metabolic profiling reveals potential metabolic markers associated with Hypoxia Inducible Factor-mediated signalling in hypoxic cancer cells

    PubMed Central

    Armitage, Emily G.; Kotze, Helen L.; Allwood, J. William; Dunn, Warwick B.; Goodacre, Royston; Williams, Kaye J.

    2015-01-01

    Hypoxia inducible factors (HIFs) plays an important role in oxygen compromised environments and therefore in tumour survival. In this research, metabolomics has been applied to study HIFs metabolic function in two cell models: mouse hepatocellular carcinoma and human colon carcinoma, whereby the metabolism has been profiled for a range of oxygen potentials. Wild type cells have been compared to cells deficient in HIF signalling to reveal its effect on cellular metabolism under normal oxygen conditions as well as low oxygen, hypoxic and anoxic environments. Characteristic responses to hypoxia that were conserved across both cell models involved the anti-correlation between 2-hydroxyglutarate, 2-oxoglutarate, fructose, hexadecanoic acid, hypotaurine, pyruvate and octadecenoic acid with 4-hydroxyproline, aspartate, cysteine, glutamine, lysine, malate and pyroglutamate. Further to this, network-based correlation analysis revealed HIF specific pathway responses to each oxygen condition that were also conserved between cell models. From this, 4-hydroxyproline was revealed as a regulating hub in low oxygen survival of WT cells while fructose appeared to be in HIF deficient cells. Pathways surrounding these hubs were built from the direct connections of correlated metabolites that look beyond traditional pathways in order to understand the mechanism of HIF response to low oxygen environments. PMID:26508589

  15. Physiological noise in murine solid tumours using T2*-weighted gradient-echo imaging: a marker of tumour acute hypoxia?

    NASA Astrophysics Data System (ADS)

    Baudelet, Christine; Ansiaux, Réginald; Jordan, Bénédicte F.; Havaux, Xavier; Macq, Benoit; Gallez, Bernard

    2004-08-01

    T2*-weighted gradient-echo magnetic resonance imaging (T2*-weighted GRE MRI) was used to investigate spontaneous fluctuations in tumour vasculature non-invasively. FSa fibrosarcomas, implanted intramuscularly (i.m.) in the legs of mice, were imaged at 4.7 T, over a 30 min or 1 h sampling period. On a voxel-by-voxel basis, time courses of signal intensity were analysed using a power spectrum density (PSD) analysis to isolate voxels for which signal changes did not originate from Gaussian white noise or linear drift. Under baseline conditions, the tumours exhibited spontaneous signal fluctuations showing spatial and temporal heterogeneity over the tumour. Statistically significant fluctuations occurred at frequencies ranging from 1 cycle/3 min to 1 cycle/h. The fluctuations were independent of the scanner instabilities. Two categories of signal fluctuations were reported: (i) true fluctuations (TFV), i.e., sequential signal increase and decrease, and (ii) profound drop in signal intensity with no apparent signal recovery (SDV). No temporal correlation between tumour and contralateral muscle fluctuations was observed. Furthermore, treatments aimed at decreasing perfusion-limited hypoxia, such as carbogen combined with nicotinamide and flunarizine, decreased the incidence of tumour T2*-weighted GRE fluctuations. We also tracked dynamic changes in T2* using multiple GRE imaging. Fluctuations of T2* were observed; however, fluctuation maps using PSD analysis could not be generated reliably. An echo-time dependency of the signal fluctuations was observed, which is typical to physiological noise. Finally, at the end of T2*-weighted GRE MRI acquisition, a dynamic contrast-enhanced MRI was performed to characterize the microenvironment in which tumour signal fluctuations occurred in terms of vessel functionality, vascularity and microvascular permeability. Our data showed that TFV were predominantly located in regions with functional vessels, whereas SDV occurred in regions

  16. Markers

    ERIC Educational Resources Information Center

    Healthy Schools Network, Inc., 2011

    2011-01-01

    Dry erase whiteboards come with toxic dry erase markers and toxic cleaning products. Dry erase markers labeled "nontoxic" are not free of toxic chemicals and can cause health problems. Children are especially vulnerable to environmental health hazards; moreover, schools commonly have problems with indoor air pollution, as they are more densely…

  17. Klotho and S100A8/A9 as Discriminative Markers between Pre-Renal and Intrinsic Acute Kidney Injury

    PubMed Central

    Kim, Ae Jin; Ro, Han; Kim, Hyunsook; Chang, Jae Hyun; Lee, Hyun Hee; Chung, Wookyung; Jung, Ji Yong

    2016-01-01

    Early detection and accurate differentiation of the cause of AKI may improve the prognosis of the patient. However, to date, there are few reliable biomarkers that can discriminate between pre-renal and intrinsic AKI. In this study, we determined whether AKI is associated with altered serum and urinary levels of Klotho, S100A8/A9 (an endogenous ligand of toll-like receptor 4), and neutrophil gelatinase-associated lipocalin (NGAL), which may allow differentiation between pre-renal and intrinsic AKI. A volume-depleted pre-renal AKI model was induced in male Sprague Dawley rats fed a low-salt diet (0.03%) without water 96 h before two intraperitoneal (IP) injections of furosemide (20 mg/kg) at a 24 h interval. In contrast, in the cisplatin-induced intrinsic AKI model, animals were given a single IP injection of cisplatin (5 mg/kg). All of the animals were euthanized 72 h after the first IP injection. Serum and urinary levels of Klotho, S100A8/A9, and NGAL were measured using an enzyme-linked immunosorbent assay. We also performed a proof-of-concept cross-sectional study to measure serum and urinary biomarkers in 61 hospitalized patients with established AKI. Compared to the intrinsic AKI group, the pre-renal AKI group showed a marked depression in urinary Klotho levels (13.21±17.32 vs. 72.97±17.96 pg/mL; P = 0.002). In addition, the intrinsic AKI group showed marked elevation of S100A8/A9 levels compared to the pre-renal AKI group (2629.97±598.05 ng/mL vs. 685.09±111.65 ng/mL; P = 0.002 in serum; 3361.11±250.86 ng/mL vs. 741.72±101.96 ng/mL; P = 0.003 in urine). There was no difference in serum and urinary NGAL levels between the pre-renal and intrinsic AKI groups. The proof-of-concept study with the hospitalized AKI patients also demonstrated decreased urinary Klotho in pre-renal AKI patients and increased urinary S100A8/A9 concentrations in intrinsic AKI patients. The attenuation of urinary Klotho and increase in urinary S100A8/A9 may allow differentiation

  18. Copper-64-diacetyl-bis(N(4)-methylthiosemicarbazone) Pharmacokinetics in FaDu Xenograft Tumors and Correlation With Microscopic Markers of Hypoxia

    SciTech Connect

    McCall, Keisha C.; Humm, John L.; Bartlett, Rachel; Reese, Megan; Carlin, Sean

    2012-11-01

    Purpose: The behavior of copper-64-diacetyl-bis(N(4)-methylthiosemicarbazone) ({sup 64}Cu-ATSM) in hypoxic tumors was examined through a combination of in vivo dynamic positron emission tomography (PET) and ex vivo autoradiographic and histologic evaluation using a xenograft model of head-and-neck squamous cell carcinoma. Methods and Materials: {sup 64}Cu-ATSM was administered during dynamic PET imaging, and temporal changes in {sup 64}Cu-ATSM distribution within tumors were evaluated for at least 1 hour and up to 18 hours. Animals were sacrificed at either 1 hour (cohort A) or after 18 hours (cohort B) postinjection of radiotracer and autoradiography performed. Ex vivo analysis of microenvironment subregions was conducted by immunohistochemical staining for markers of hypoxia (pimonidazole hydrochloride) and blood flow (Hoechst-33342). Results: Kinetic analysis revealed rapid uptake of radiotracer by tumors. The net influx (K{sub i}) constant was 12-fold that of muscle, whereas the distribution volume (V{sub d}) was 5-fold. PET images showed large tumor-to-muscle ratios, which continually increased over the entire 18-hour course of imaging. However, no spatial changes in {sup 64}Cu-ATSM distribution occurred in PET imaging at 20 minutes postinjection. Microscopic intratumoral distribution of {sup 64}Cu-ATSM and pimonidazole were not correlated at 1 hour or after 18 hours postinjection, nor was {sup 64}Cu-ATSM and Hoechst-33342. Conclusions: The oxygen partial pressures at which {sup 64}Cu-ATSM and pimonidazole are reduced and bound in cells are theorized to be distinct and separable. However, this study demonstrated that microscopic distributions of these tracers within tumors are independent. Researchers have shown {sup 64}Cu-ATSM uptake to be specific to malignant expression, and this work has also demonstrated clear tumor targeting by the radiotracer.

  19. Immunohistochemical detection of osteopontin in advanced head-and-neck cancer: Prognostic role and correlation with oxygen electrode measurements, hypoxia-inducible-factor-1{alpha}-related markers, and hemoglobin levels

    SciTech Connect

    Bache, Matthias; Reddemann, Rolf; Said, Harun M.; Holzhausen, Hans-Juergen; Taubert, Helge; Becker, Axel; Kuhnt, Thomas; Haensgen, Gabriele; Dunst, Juergen; Vordermark, Dirk . E-mail: vordermark_d@klinik.uni-wuerzburg.de

    2006-12-01

    Purpose: The tumor-associated glycoprotein osteopontin (OPN) is discussed as a plasma marker of tumor hypoxia. However, the association of immunohistochemical OPN expression in tumor sections with tumor oxygenation parameters (HF5, median pO{sub 2}), the hypoxia-related markers hypoxia-inducible factor-1{alpha} (HIF-1{alpha}) and carbonic anhydrase IX (CAIX), or hemoglobin and systemic vascular endothelial growth factor (VEGF) levels has not been investigated. Methods and Materials: Tumor tissue sections of 34 patients with advanced head-and-neck cancer treated with radiotherapy were assessed by immunochemistry for the expression of OPN, HIF-1{alpha}, and CA IX. Relationship of OPN expression with tumor oxygenation parameters (HF5, median pO{sub 2}), HIF-1{alpha} and CA IX expression, hemoglobin and serum VEGF level, and clinical parameters was studied. Results: Bivariate analysis showed a significant correlation of positive OPN staining with low hemoglobin level (p = 0.02), high HIF-1{alpha} expression (p = 0.02), and high serum vascular endothelial growth factor level (p = 0.02) for advanced head-and-neck cancer. Furthermore, considering the 31 Stage IV patients, the median pO{sub 2} correlated significantly with the OPN expression (p = 0.02). OPN expression alone had only a small impact on prognosis. However, in a univariate Cox proportional hazard regression model, the expression of either OPN or HIF-1{alpha} or CA IX was associated with a 4.1-fold increased risk of death (p = 0.02) compared with negativity of all three markers. Conclusion: Osteopontin expression detected immunohistochemically is associated with oxygenation parameters in advanced head-and-neck cancer. When the results of OPN, HIF-1{alpha}, and CA IX immunohistochemistry are combined into a hypoxic profile, a strong and statistically significant impact on overall survival is found.

  20. Pre-analytical sample quality: metabolite ratios as an intrinsic marker for prolonged room temperature exposure of serum samples.

    PubMed

    Anton, Gabriele; Wilson, Rory; Yu, Zhong-Hao; Prehn, Cornelia; Zukunft, Sven; Adamski, Jerzy; Heier, Margit; Meisinger, Christa; Römisch-Margl, Werner; Wang-Sattler, Rui; Hveem, Kristian; Wolfenbuttel, Bruce; Peters, Annette; Kastenmüller, Gabi; Waldenberger, Melanie

    2015-01-01

    Advances in the "omics" field bring about the need for a high number of good quality samples. Many omics studies take advantage of biobanked samples to meet this need. Most of the laboratory errors occur in the pre-analytical phase. Therefore evidence-based standard operating procedures for the pre-analytical phase as well as markers to distinguish between 'good' and 'bad' quality samples taking into account the desired downstream analysis are urgently needed. We studied concentration changes of metabolites in serum samples due to pre-storage handling conditions as well as due to repeated freeze-thaw cycles. We collected fasting serum samples and subjected aliquots to up to four freeze-thaw cycles and to pre-storage handling delays of 12, 24 and 36 hours at room temperature (RT) and on wet and dry ice. For each treated aliquot, we quantified 127 metabolites through a targeted metabolomics approach. We found a clear signature of degradation in samples kept at RT. Storage on wet ice led to less pronounced concentration changes. 24 metabolites showed significant concentration changes at RT. In 22 of these, changes were already visible after only 12 hours of storage delay. Especially pronounced were increases in lysophosphatidylcholines and decreases in phosphatidylcholines. We showed that the ratio between the concentrations of these molecule classes could serve as a measure to distinguish between 'good' and 'bad' quality samples in our study. In contrast, we found quite stable metabolite concentrations during up to four freeze-thaw cycles. We concluded that pre-analytical RT handling of serum samples should be strictly avoided and serum samples should always be handled on wet ice or in cooling devices after centrifugation. Moreover, serum samples should be frozen at or below -80°C as soon as possible after centrifugation. PMID:25823017

  1. Pre-Analytical Sample Quality: Metabolite Ratios as an Intrinsic Marker for Prolonged Room Temperature Exposure of Serum Samples

    PubMed Central

    Anton, Gabriele; Wilson, Rory; Yu, Zhong-hao; Prehn, Cornelia; Zukunft, Sven; Adamski, Jerzy; Heier, Margit; Meisinger, Christa; Römisch-Margl, Werner; Wang-Sattler, Rui; Hveem, Kristian; Wolfenbuttel, Bruce; Peters, Annette; Kastenmüller, Gabi; Waldenberger, Melanie

    2015-01-01

    Advances in the “omics” field bring about the need for a high number of good quality samples. Many omics studies take advantage of biobanked samples to meet this need. Most of the laboratory errors occur in the pre-analytical phase. Therefore evidence-based standard operating procedures for the pre-analytical phase as well as markers to distinguish between ‘good’ and ‘bad’ quality samples taking into account the desired downstream analysis are urgently needed. We studied concentration changes of metabolites in serum samples due to pre-storage handling conditions as well as due to repeated freeze-thaw cycles. We collected fasting serum samples and subjected aliquots to up to four freeze-thaw cycles and to pre-storage handling delays of 12, 24 and 36 hours at room temperature (RT) and on wet and dry ice. For each treated aliquot, we quantified 127 metabolites through a targeted metabolomics approach. We found a clear signature of degradation in samples kept at RT. Storage on wet ice led to less pronounced concentration changes. 24 metabolites showed significant concentration changes at RT. In 22 of these, changes were already visible after only 12 hours of storage delay. Especially pronounced were increases in lysophosphatidylcholines and decreases in phosphatidylcholines. We showed that the ratio between the concentrations of these molecule classes could serve as a measure to distinguish between ‘good’ and ‘bad’ quality samples in our study. In contrast, we found quite stable metabolite concentrations during up to four freeze-thaw cycles. We concluded that pre-analytical RT handling of serum samples should be strictly avoided and serum samples should always be handled on wet ice or in cooling devices after centrifugation. Moreover, serum samples should be frozen at or below -80°C as soon as possible after centrifugation. PMID:25823017

  2. Imaging tumour hypoxia with positron emission tomography

    PubMed Central

    Fleming, I N; Manavaki, R; Blower, P J; West, C; Williams, K J; Harris, A L; Domarkas, J; Lord, S; Baldry, C; Gilbert, F J

    2015-01-01

    Hypoxia, a hallmark of most solid tumours, is a negative prognostic factor due to its association with an aggressive tumour phenotype and therapeutic resistance. Given its prominent role in oncology, accurate detection of hypoxia is important, as it impacts on prognosis and could influence treatment planning. A variety of approaches have been explored over the years for detecting and monitoring changes in hypoxia in tumours, including biological markers and noninvasive imaging techniques. Positron emission tomography (PET) is the preferred method for imaging tumour hypoxia due to its high specificity and sensitivity to probe physiological processes in vivo, as well as the ability to provide information about intracellular oxygenation levels. This review provides an overview of imaging hypoxia with PET, with an emphasis on the advantages and limitations of the currently available hypoxia radiotracers. PMID:25514380

  3. Hypoxia and Hypoxia-Inducible Factors in Leukemias.

    PubMed

    Deynoux, Margaux; Sunter, Nicola; Hérault, Olivier; Mazurier, Frédéric

    2016-01-01

    Despite huge improvements in the treatment of leukemia, the percentage of patients suffering relapse still remains significant. Relapse most often results from a small number of leukemic stem cells (LSCs) within the bone marrow, which are able to self-renew, and therefore reestablish the full tumor. The marrow microenvironment contributes considerably in supporting the protection and development of leukemic cells. LSCs share specific niches with normal hematopoietic stem cells with the niche itself being composed of a variety of cell types, including mesenchymal stem/stromal cells, bone cells, immune cells, neuronal cells, and vascular cells. A hallmark of the hematopoietic niche is low oxygen partial pressure, indeed this hypoxia is necessary for the long-term maintenance of hematopoietic stem/progenitor cells. Hypoxia is a strong signal, principally maintained by members of the hypoxia-inducible factor (HIF) family. In solid tumors, it has been well established that hypoxia triggers intrinsic metabolic changes and microenvironmental modifications, such as the stimulation of angiogenesis, through activation of HIFs. As leukemia is not considered a "solid" tumor, the role of oxygen in the disease was presumed to be inconsequential and remained long overlooked. This view has now been revised since hypoxia has been shown to influence leukemic cell proliferation, differentiation, and resistance to chemotherapy. However, the role of HIF proteins remains controversial with HIFs being considered as either oncogenes or tumor suppressor genes, depending on the study and model. The purpose of this review is to highlight our knowledge of hypoxia and HIFs in leukemic development and therapeutic resistance and to discuss the recent hypoxia-based strategies proposed to eradicate leukemias. PMID:26955619

  4. Hypoxia and Hypoxia-Inducible Factors in Leukemias

    PubMed Central

    Deynoux, Margaux; Sunter, Nicola; Hérault, Olivier; Mazurier, Frédéric

    2016-01-01

    Despite huge improvements in the treatment of leukemia, the percentage of patients suffering relapse still remains significant. Relapse most often results from a small number of leukemic stem cells (LSCs) within the bone marrow, which are able to self-renew, and therefore reestablish the full tumor. The marrow microenvironment contributes considerably in supporting the protection and development of leukemic cells. LSCs share specific niches with normal hematopoietic stem cells with the niche itself being composed of a variety of cell types, including mesenchymal stem/stromal cells, bone cells, immune cells, neuronal cells, and vascular cells. A hallmark of the hematopoietic niche is low oxygen partial pressure, indeed this hypoxia is necessary for the long-term maintenance of hematopoietic stem/progenitor cells. Hypoxia is a strong signal, principally maintained by members of the hypoxia-inducible factor (HIF) family. In solid tumors, it has been well established that hypoxia triggers intrinsic metabolic changes and microenvironmental modifications, such as the stimulation of angiogenesis, through activation of HIFs. As leukemia is not considered a “solid” tumor, the role of oxygen in the disease was presumed to be inconsequential and remained long overlooked. This view has now been revised since hypoxia has been shown to influence leukemic cell proliferation, differentiation, and resistance to chemotherapy. However, the role of HIF proteins remains controversial with HIFs being considered as either oncogenes or tumor suppressor genes, depending on the study and model. The purpose of this review is to highlight our knowledge of hypoxia and HIFs in leukemic development and therapeutic resistance and to discuss the recent hypoxia-based strategies proposed to eradicate leukemias. PMID:26955619

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

    PubMed Central

    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

  6. Immunohistochemical Detection of Changes in Tumor Hypoxia

    SciTech Connect

    Russell, James Carlin, Sean; Burke, Sean A.; Wen Bixiu; Yang, Kwang Mo; Ling, C. Clifton

    2009-03-15

    Purpose: Although hypoxia is a known prognostic factor, its effect will be modified by the rate of reoxygenation and the extent to which the cells are acutely hypoxic. We tested the ability of exogenous and endogenous markers to detect reoxygenation in a xenograft model. Our technique might be applicable to stored patient samples. Methods and Materials: The human colorectal carcinoma line, HT29, was grown in nude mice. Changes in tumor hypoxia were examined by injection of pimonidazole, followed 24 hours later by EF5. Cryosections were stained for these markers and for carbonic anhydrase IX (CAIX) and hypoxia-inducible factor 1{alpha} (HIF1{alpha}). Tumor hypoxia was artificially manipulated by carbogen exposure. Results: In unstressed tumors, all four markers showed very similar spatial distributions. After carbogen treatment, pimonidazole and EF5 could detect decreased hypoxia. HIF1{alpha} staining was also decreased relative to CAIX, although the effect was less pronounced than for EF5. Control tumors displayed small regions that had undergone spontaneous changes in tumor hypoxia, as judged by pimonidazole relative to EF5; most of these changes were reflected by CAIX and HIF1{alpha}. Conclusion: HIF1{alpha} can be compared with either CAIX or a previously administered nitroimidazole to provide an estimate of reoxygenation.

  7. Radiosynthesis of the Tumor Hypoxia Marker [18F]TFMISO via O-[18F]Trifluoroethylation Reveals a Striking Difference Between Trifluoroethyl Tosylate and Iodide in Regiochemical Reactivity Toward Oxygen Nucleophiles

    PubMed Central

    Suehiro, Makiko; Yang, Guangbin; Torchon, Geralda; Ackerstaff, Ellen; Humm, John; Koutcher, Jason; Ouerfelli, Ouathek

    2014-01-01

    The MRI hypoxia marker trifluoro-misonidazole (TFMISO) [1-(2-nitro-1H-imidazol-1-yl)-3-(2,2,2-trifluoroethoxy)propan-2-ol] was successfully labeled with 18F to expand its role into a bimodal PET/MRI probe. 18F-Labeling was achieved via a 3-step procedure in which 2,2,2-[18F]trifluoroethyl p-toluenesulfonate prepared by 18F-19F exchange served as the [18F]trifluoroethylating agent. The O-[18F]trifluoroethylation reaction proceeded efficiently to give the intermediate 1,2-epoxy-3-(2,2,2-[18F]trifluoroethoxy)propane, with approximately 60% of 18F incorporated from the tosylate precursor, which was condensed with 2-nitroimidazole to yield [18F]TFMISO. Approximately 40% of the [18F]trifluoroethyl tosylate precursor was converted into the final product. In stark contrast, 2,2,2-[18F]trifluoroethyl iodide failed to produce [18F]TFMISO, giving instead 1,1-[18F]difluoro-2-iodoethoxy and 1-[18F]fluoro-2-iodovinyloxy analogs of [18F]TFMISO. Thus, this investigation has identified 2,2,2-[18F]trifluoroethyl tosylate as an excellent [18F]trifluoroethylating agent, which can convert efficiently an alcohol into the corresponding [18F]trifluoroethyl ether. PMID:21398131

  8. Assessment of tumour hypoxia for prediction of response to therapy and cancer prognosis

    PubMed Central

    Jubb, Adrian M; Buffa, Francesca M; Harris, Adrian L

    2010-01-01

    Abstract Tumour cells exploit both genetic and adaptive means to survive and proliferate in hypoxic microenvironments, resulting in the outgrowth of more aggressive tumour cell clones. Direct measurements of tumour oxygenation, and surrogate markers of the hypoxic response in tumours (for instance, hypoxia inducible factor-1α, carbonic anhydrase 9 and glucose transporter-1) are well-established prognostic markers in solid cancers. However, individual markers do not fully capture the complex, dynamic and heterogeneous hypoxic response in cancer. To overcome this, expression profiling has been employed to identify hypoxia signatures in cohorts or models of human cancer. Several of these hypoxia signatures have demonstrated prognostic significance in independent cancer datasets. Nevertheless, individual hypoxia markers have been shown to predict the benefit from hypoxia-modifying or anti-angiogenic therapies. This review aims to discuss the clinical impact of translational work on hypoxia markers and to explore future directions for research in this area. PMID:19840191

  9. [Refractory hypoxia].

    PubMed

    Cuchard, P; Guillemin, P

    2011-04-27

    We report a case of refractory hypoxia in an 85 years old smoker patient, who is known for cardiac and pulmonary comorbidities. The whole clinical picture at the time of his admission to hospital was pointing to a cardiac failure or a pneumonia that were causing the respiratory insufficiency. Despite an optimal treatment which stabilised these conditions, the patient remained severely hypoxic, but with relatively few symptoms. The non response to the oxygen and the worsening of the oxygen saturation when changing from the lying to the sitting (or supine) position finally evoke the syndrome of platypnea-orthodeoxia caused by a cardiac right to left shunt; that diagnosis was confirmed by a cardiac ultrasound with contrast which revealed an important inter-auricular shunt. The patient didn't wish to undertake the curative treatment (shunt closure). PMID:21526473

  10. Is carbonic anhydrase IX a validated target for molecular imaging of cancer and hypoxia?

    PubMed Central

    Li, Jianbo; Zhang, Guojian; Wang, Xuemei; Li, Xiao-Feng

    2015-01-01

    ABSTRACT  The presence of hypoxia is a general feature of most solid malignancies, and hypoxia is considered as one of major factors for anticancer therapy failure. Carbonic anhydrase IX (CAIX) has been reported to be an endogenous hypoxia marker, CAIX monoclonal antibodies, their segments and inhibitors are developed for CAIX imaging. However, growing evidence indicates that CAIX expression under hypoxia condition may be cancer cell lines or cancer-type dependent. Here we review the current literature on CAIX and discuss the advantage and limitation of CAIX as a target for tumor hypoxia imaging. Accordingly, CAIX would be unreliable as a universal target for cancer and tumor hypoxia visualization. PMID:25963430

  11. Immunohistochemical Detection of Changes in Tumor Hypoxia

    PubMed Central

    Russell, James; Carlin, Sean; Burke, Sean A.; Wen, Bixiu; Yang, Kwang Mo; Ling, C Clifton

    2009-01-01

    Purpose Although hypoxia is a known prognostic factor, its impact will be modified by the rate of reoxygenation and the extent to which cells are acutely hypoxic. We tested the ability of exogenous and endogenous markers to detect reoxygenation in a xenograft model. Our technique may be applicable to stored patient samples. Methods and Materials The human colorectal carcinoma line, HT29 was grown in nude mice. Changes in tumor hypoxia were examined by injection of pimonidazole followed 24 hours later by EF5. Cryosections were stained for these markers and for CAIX and HIF1α. Tumor hypoxia was artificially manipulated by carbogen exposure. Results In unstressed tumors, all four markers showed very similar spatial distributions. After carbogen treatment, pimonidazole and EF5 could detect decreased hypoxia. HIF1α staining was also decreased relative to CAIX, though the effect was less pronounced than for EF5. Control tumors displayed small regions that had undergone spontaneous changes in tumor hypoxia, as judged by pimonidazole relative to EF5; most of these changes were reflected by CAIX and HIF1α Conclusions HIF1α can be compared to either CAIX or a previously administered nitroimidazole to provide an estimate of reoxygenation. PMID:19251089

  12. Hypoxia induces adipogenic differentitation of myoblastic cell lines

    SciTech Connect

    Itoigawa, Yoshiaki; Kishimoto, Koshi N.; Okuno, Hiroshi; Sano, Hirotaka; Kaneko, Kazuo; Itoi, Eiji

    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.

  13. Hypoxia. 3. Hypoxia and neurotransmitter synthesis

    PubMed Central

    2011-01-01

    Central and peripheral neurons as well as neuroendocrine cells express a variety of neurotransmitters/modulators that play critical roles in regulation of physiological systems. The synthesis of several neurotransmitters/modulators is regulated by O2-requiring rate-limiting enzymes. Consequently, hypoxia resulting from perturbations in O2 homeostasis can affect neuronal functions by altering neurotransmitter synthesis. Two broad categories of hypoxia are frequently encountered: continuous hypoxia (CH) and intermittent hypoxia (IH). CH is often seen during high altitude sojourns, whereas IH is experienced in sleep-disordered breathing with recurrent apneas (i.e., brief, repetitive cessations of breathing). This article presents what is currently known on the effects of both forms of hypoxia on neurotransmitter levels and neurotransmitter synthesizing enzymes in the central and peripheral nervous systems. PMID:21270298

  14. Mapping an intrinsic MR property of gray matter in auditory cortex of living humans: a possible marker for primary cortex and hemispheric differences.

    PubMed

    Sigalovsky, Irina S; Fischl, Bruce; Melcher, Jennifer R

    2006-10-01

    Recently, magnetic resonance properties of cerebral gray matter have been spatially mapped--in vivo--over the cortical surface. In one of the first neuroscientific applications of this approach, this study explores what can be learned about auditory cortex in living humans by mapping longitudinal relaxation rate (R1), a property related to myelin content. Gray matter R1 (and thickness) showed repeatable trends, including the following: (1) Regions of high R1 were always found overlapping posteromedial Heschl's gyrus. They also sometimes occurred in planum temporale and never in other parts of the superior temporal lobe. We hypothesize that the high R1 overlapping Heschl's gyrus (which likely indicates dense gray matter myelination) reflects auditory koniocortex (i.e., primary cortex), a heavily myelinated area that shows comparable overlap with the gyrus. High R1 overlapping Heschl's gyrus was identified in every instance suggesting that R1 may ultimately provide a marker for koniocortex in individuals. Such a marker would be significant for auditory neuroimaging, which has no standard means (anatomic or physiologic) for localizing cortical areas in individual subjects. (2) Inter-hemispheric comparisons revealed greater R1 on the left on Heschl's gyrus, planum temporale, superior temporal gyrus and superior temporal sulcus. This asymmetry suggests greater gray matter myelination in left auditory cortex, which may be a substrate for the left hemisphere's specialized processing of speech, language, and rapid acoustic changes. These results indicate that in vivo R1 mapping can provide new insights into the structure of human cortical gray matter and its relation to function. PMID:16806989

  15. Bayesian Inference of Tumor Hypoxia

    NASA Astrophysics Data System (ADS)

    Gunawan, R.; Tenti, G.; Sivaloganathan, S.

    2009-12-01

    Tumor hypoxia is a state of oxygen deprivation in tumors. It has been associated with aggressive tumor phenotypes and with increased resistance to conventional cancer therapies. In this study, we report on the application of Bayesian sequential analysis in estimating the most probable value of tumor hypoxia quantification based on immunohistochemical assays of a biomarker. The `gold standard' of tumor hypoxia assessment is a direct measurement of pO2 in vivo by the Eppendorf polarographic electrode, which is an invasive technique restricted to accessible sites and living tissues. An attractive alternative is immunohistochemical staining to detect proteins expressed by cells during hypoxia. Carbonic anhydrase IX (CAIX) is an enzyme expressed on the cell membrane during hypoxia to balance the immediate extracellular microenvironment. CAIX is widely regarded as a surrogate marker of chronic hypoxia in various cancers. The study was conducted with two different experimental procedures. The first data set was a group of three patients with invasive cervical carcinomas, from which five biopsies were obtained. Each of the biopsies was fully sectioned and from each section, the proportion of CAIX-positive cells was estimated. Measurements were made by image analysis of multiple deep sections cut through these biopsies, labeled for CAIX using both immunofluorescence and immunohistochemical techniques [1]. The second data set was a group of 24 patients, also with invasive cervical carcinomas, from which two biopsies were obtained. Bayesian parameter estimation was applied to obtain a reliable inference about the proportion of CAIX-positive cells within the carcinomas, based on the available biopsies. From the first data set, two to three biopsies were found to be sufficient to infer the overall CAIX percentage in the simple form: best estimate±uncertainty. The second data-set led to a similar result in 70% of the cases. In the remaining cases Bayes' theorem warned us

  16. Hypoxia in Microscopic Tumors

    PubMed Central

    Li, Xiao-Feng; O’Donoghue, Joseph A

    2008-01-01

    Tumor hypoxia has been commonly observed in a broad spectrum of primary solid malignancies. Hypoxia is associated with tumor progression, increased aggressiveness, enhanced metastatic potential and poor prognosis. Hypoxic tumor cells are resistant to radiotherapy and some forms of chemotherapy. Using an animal model, we recently showed that microscopic tumors less than 1 mm diameter were severely hypoxic. In this review, models and techniques for the study of hypoxia in microscopic tumors are discussed. PMID:18384940

  17. Hypoxia in Diabetic Kidneys

    PubMed Central

    Takiyama, Yumi; Haneda, Masakazu

    2014-01-01

    Diabetic nephropathy (DN) is now a leading cause of end-stage renal disease. In addition, DN accounts for the increased mortality in type 1 and type 2 diabetes, and then patients without DN achieve long-term survival compatible with general population. Hypoxia represents an early event in the development and progression of DN, and hypoxia-inducible factor- (HIF-) 1 mediates the metabolic responses to renal hypoxia. Diabetes induces the “fraternal twins” of hypoxia, that is, pseudohypoxia and hypoxia. The kidneys are susceptible to hyperoxia because they accept 20% of the cardiac output. Therefore, the kidneys have specific vasculature to avoid hyperoxia, that is, AV oxygen shunting. The NAD-dependent histone deacetylases (HDACs) sirtuins are seven mammalian proteins, SIRTs 1–7, which are known to modulate longevity and metabolism. Recent studies demonstrated that some isoforms of sirtuins inhibit the activation of HIF by deacetylation or noncatalyzing effects. The kidneys, which have a vascular system that protects them against hyperoxia, unfortunately experience extraordinary hypernutrition today. Then, an unexpected overload of glucose augments the oxygen consumption, which ironically results in hypoxia. This review highlights the primary role of HIF in diabetic kidneys for the metabolic adaptation to diabetes-induced hypoxia. PMID:25054148

  18. Hypoxia-Inducible Hydrogels

    PubMed Central

    Park, Kyung Min; Gerecht, Sharon

    2014-01-01

    Oxygen is vital for the existence of all multicellular organisms, acting as a signaling molecule regulating cellular activities. Specifically, hypoxia, which occurs when the partial pressure of oxygen falls below 5%, plays a pivotal role during development, regeneration, and cancer. Here we report a novel hypoxia-inducible (HI) hydrogel composed of gelatin and ferulic acid that can form hydrogel networks via oxygen consumption in a laccase-mediated reaction. Oxygen levels and gradients within the hydrogels can be accurately controlled and precisely predicted. We demonstrate that HI hydrogels guide vascular morphogenesis in vitro via hypoxia-inducible factors activation of matrix metalloproteinases and promote rapid neovascularization from the host tissue during subcutaneous wound healing. The HI hydrogel is a new class of biomaterials that may prove useful in many applications, ranging from fundamental studies of developmental, regenerative and disease processes through the engineering of healthy and diseased tissue models towards the treatment of hypoxia-regulated disorders. PMID:24909742

  19. Intrinsic n

    SciTech Connect

    Zhang, S. B.; Wei, S.-H.; Zunger, Alex

    2001-02-15

    ZnO typifies a class of materials that can be doped via native defects in only one way: either n type or p type. We explain this asymmetry in ZnO via a study of its intrinsic defect physics, including Zn{sub O}, Zn{sub i}, V{sub O}, O{sub i}, and V{sub Zn} and n-type impurity dopants, Al and F. We find that ZnO is n type at Zn-rich conditions. This is because (i) the Zn interstitial, Zn{sub i}, is a shallow donor, supplying electrons; (ii) its formation enthalpy is low for both Zn-rich and O-rich conditions, so this defect is abundant; and (iii) the native defects that could compensate the n-type doping effect of Zn{sub i} (interstitial O, O{sub i}, and Zn vacancy, V{sub Zn}), have high formation enthalpies for Zn-rich conditions, so these ''electron killers'' are not abundant. We find that ZnO cannot be doped p type via native defects (O{sub i},V{sub Zn}) despite the fact that they are shallow (i.e., supplying holes at room temperature). This is because at both Zn-rich and O-rich conditions, the defects that could compensate p-type doping (V{sub O},Zn{sub i},Zn{sub O}) have low formation enthalpies so these ''hole killers'' form readily. Furthermore, we identify electron-hole radiative recombination at the V{sub O} center as the source of the green luminescence. In contrast, a large structural relaxation of the same center upon double hole capture leads to slow electron-hole recombination (either radiative or nonradiative) responsible for the slow decay of photoconductivity.

  20. Hypoxia. 4. Hypoxia and ion channel function

    PubMed Central

    Polak, Jan

    2011-01-01

    The ability to sense and respond to oxygen deprivation is required for survival; thus, understanding the mechanisms by which changes in oxygen are linked to cell viability and function is of great importance. Ion channels play a critical role in regulating cell function in a wide variety of biological processes, including neuronal transmission, control of ventilation, cardiac contractility, and control of vasomotor tone. Since the 1988 discovery of oxygen-sensitive potassium channels in chemoreceptors, the effect of hypoxia on an assortment of ion channels has been studied in an array of cell types. In this review, we describe the effects of both acute and sustained hypoxia (continuous and intermittent) on mammalian ion channels in several tissues, the mode of action, and their contribution to diverse cellular processes. PMID:21178108

  1. KIDNEY HYPOXIA, DUE TO INCREASED OXYGEN CONSUMPTION, INDUCES NEPHROPATHY INDEPENDENTLY OF HYPERGLYCEMIA AND OXIDATIVE STRESS

    PubMed Central

    Friederich-Persson, Malou; Thörn, Erik; Hansell, Peter; Nangaku, Masaomi; Levin, Max; Palm, Fredrik

    2013-01-01

    Diabetic nephropathy is strongly associated with both increased oxidative stress and kidney tissue hypoxia. The increased oxidative stress causes increased kidney oxygen consumption resulting in kidney tissue hypoxia. It has so far been difficult to determine the role of kidney hypoxia per se for the development of nephropathy. We tested the hypothesis that kidney hypoxia, without confounding factors such as hyperglycemia or elevated oxidative stress, results in nephropathy. To induce kidney hypoxia, dinitrophenol (30 mg/day/kg by gavage), a mitochondrial uncoupler that increases oxygen consumption and causes kidney hypoxia, was administered for 30 consecutive days to rats. Thereafter, glomerular filtration rate, renal blood flow, kidney oxygen consumption, kidney oxygen tension, kidney concentrations of glucose and glycogen, markers of oxidative stress, urinary protein excretion and histology were determined and compared to vehicle-treated controls. Dinitrophenol did not affect arterial blood pressure, renal blood flow, glomerular filtration rate, blood glucose or markers of oxidative stress, but increased kidney oxygen consumption and reduced cortical and medullary concentrations of glucose and glycogen and resulted in intrarenal tissue hypoxia. Furthermore, dinitrophenol treatment increased urinary protein excretion, kidney vimentin expression and infiltration of inflammatory cells. In conclusion, increased mitochondrial oxygen consumption results in kidney hypoxia and subsequent nephropathy. Importantly, these results demonstrate that kidney tissue hypoxia per se, without confounding hyperglycemia or oxidative stress, may be sufficient to initiate the development of nephropathy and therefore demonstrate a new interventional target for treating kidney disease. PMID:24019401

  2. Hypoxia Promotes Osteogenesis but Suppresses Adipogenesis of Human Mesenchymal Stromal Cells in a Hypoxia-Inducible Factor-1 Dependent Manner

    PubMed Central

    Lohanatha, Ferenz L.; Hahne, Martin; Strehl, Cindy; Fangradt, Monique; Tran, Cam Loan; Schönbeck, Kerstin; Hoff, Paula; Ode, Andrea; Perka, Carsten; Duda, Georg N.; Buttgereit, Frank

    2012-01-01

    Background Bone fracture initiates a series of cellular and molecular events including the expression of hypoxia-inducible factor (HIF)-1. HIF-1 is known to facilitate recruitment and differentiation of multipotent human mesenchymal stromal cells (hMSC). Therefore, we analyzed the impact of hypoxia and HIF-1 on the competitive differentiation potential of hMSCs towards adipogenic and osteogenic lineages. Methodology/Principal Findings Bone marrow derived primary hMSCs cultured for 2 weeks either under normoxic (app. 18% O2) or hypoxic (less than 2% O2) conditions were analyzed for the expression of MSC surface markers and for expression of the genes HIF1A, VEGFA, LDHA, PGK1, and GLUT1. Using conditioned medium, adipogenic or osteogenic differentiation as verified by Oil-Red-O or von-Kossa staining was induced in hMSCs under either normoxic or hypoxic conditions. The expression of HIF1A and VEGFA was measured by qPCR. A knockdown of HIF-1α by lentiviral transduction was performed, and the ability of the transduced hMSCs to differentiate into adipogenic and osteogenic lineages was analyzed. Hypoxia induced HIF-1α and HIF-1 target gene expression, but did not alter MSC phenotype or surface marker expression. Hypoxia (i) suppressed adipogenesis and associated HIF1A and PPARG gene expression in hMSCs and (ii) enhanced osteogenesis and associated HIF1A and RUNX2 gene expression. shRNA-mediated knockdown of HIF-1α enhanced adipogenesis under both normoxia and hypoxia, and suppressed hypoxia-induced osteogenesis. Conclusions/Significance Hypoxia promotes osteogenesis but suppresses adipogenesis of human MSCs in a competitive and HIF-1-dependent manner. We therefore conclude that the effects of hypoxia are crucial for effective bone healing, which may potentially lead to the development of novel therapeutic approaches. PMID:23029528

  3. MicroRNA-584-3p, a novel tumor suppressor and prognostic marker, reduces the migration and invasion of human glioma cells by targeting hypoxia-induced ROCK1

    PubMed Central

    Xue, Hao; Guo, Xing; Han, Xiao; Yan, Shaofeng; Zhang, Jinsen; Xu, Shugang; Li, Tong; Guo, Xiaofan; Zhang, Ping; Gao, Xiao; Liu, Qinglin; Li, Gang

    2016-01-01

    Here, we report that microRNA-584-3p (miR-584-3p) is up-regulated in hypoxic glioma cells and in high-grade human glioma tumors (WHO grades III–IV) relative to normoxic cells and to low-grade tumors (WHO grades I–II), respectively. The postoperative survival time was significantly prolonged in the high-grade glioma patients with high miR-584-3p expression compared with those with low miR-584-3p expression. miR-584-3p may function as a potent tumor suppressor and as a prognostic biomarker for malignant glioma. However, the molecular mechanisms underlying these properties remain poorly understood. Our mechanistic studies revealed that miR-584-3p suppressed the migration and invasion of glioma cells by disrupting hypoxia-induced stress fiber formation. Specifically, we have found that ROCK1 is a direct and functionally relevant target of miR-584-3p in glioma cells. Our results have demonstrated a tumor suppressive function of miR-584-3p in glioma, in which it inhibits the migration and invasion of tumor cells by antagonizing hypoxia-induced, ROCK1-dependent stress fiber formation. Our findings have potential implications for glioma gene therapy and suggest that miR-584-3p could represent a prognostic indicator for glioma. PMID:26715733

  4. Effects of hypoxia on proliferation of human cord blood-derived mesenchymal stem cells.

    PubMed

    Peng, Longying; Shu, Xiaomei; Lang, Changhui; Yu, Xiaohua

    2016-08-01

    The purpose of our study was to examine the influence of hypoxia on proliferation of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs). The mononuclear cells were separated by density gradient centrifugation from human umbilical cord blood and then, respectively, cultured under hypoxia (5 % O2) or normoxia (20 % O2). Their cell morphology, cell surface markers, β-galactosidase staining, cell growth curve, DNA cycle, and the expression of hypoxia-inducible factor-1α (HIF-1α) were evaluated. We found that hypoxia, in part via HIF-1α, improved the proliferation efficiency, and prevented senescence of hUCB-MSCs without altering their morphology and surface markers. These results demonstrated that hypoxia provides a favorable culture condition to promote hUCB-MSCs proliferation in vitro, which is a better way to obtain sufficient numbers of hUCB-MSCs for research and certainly clinical application. PMID:25742732

  5. Imaging hypoxia in gliomas

    PubMed Central

    Mendichovszky, I; Jackson, A

    2011-01-01

    Hypoxia plays a central role in tumour development, angiogenesis, growth and resistance to treatment. Owing to constant developments in medical imaging technology, significant advances have been made towards in vitro and in vivo imaging of hypoxia in a variety of tumours, including gliomas of the central nervous system. The aim of this article is to review the literature on imaging approaches currently available for measuring hypoxia in human gliomas and provide an insight into recent advances and future directions in this field. After a brief overview of hypoxia and its importance in gliomas, several methods of measuring hypoxia will be presented. These range from invasive monitoring by Eppendorf polarographic O2 microelectrodes, positron electron tomography (PET) tracers based on 2-nitroimidazole compounds [18F-labelled fluoro-misonidazole (18F-MISO) or 1-(2-[(18)F]fluoro-1-[hydroxymethyl]ethoxy)methyl-2-nitroimidazole (FRP-170)], 64Cu-ATSM Cu-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) or 99mTc- and 68Ga-labelled metronidazole (MN) agents to advanced MRI methods, such as blood oxygenation level dependent (BOLD) MRI, oxygen-enhanced MRI, diffusion-weighted MRI (DWI-MRI), dynamic contrast-enhanced MRI (DCE-MRI) and 1H-magnetic resonance spectroscopy. PMID:22433825

  6. Regulation of gene expression by hypoxia.

    PubMed

    Millhorn, D E; Czyzyk-Krzeska, M; Bayliss, D A; Lawson, E E

    1993-12-01

    The present study was undertaken to determine if gene expression for tyrosine hydroxylase (TH), the rate limiting enzyme in the biosynthesis of catecholamines, is regulated in the carotid body, sympathetic ganglia and adrenal medulla by hypoxia. We found that a reduction in oxygen tension from 21% to 10% caused a substantial increase (200% at 1 hour and 500% at 6 hours exposure) in the concentration of TH mRNA in carotid body type I cells but not in either the sympathetic ganglia or adrenal gland. In addition, we found that hypercapnia, another natural stimulus of carotid body activity, failed to enhance TH mRNA in type I cells. Removal of the sensory and sympathetic innervation of the carotid body failed to prevent the induction of TH mRNA by hypoxia in type I cells. Our results show that TH gene expression is regulated by hypoxia in the carotid body but not in other peripheral catecholamine synthesizing tissue and that the regulatory mechanism is intrinsic to type I cells. PMID:7909954

  7. Use of Molecular Imaging Markers of Glycolysis, Hypoxia and Proliferation (18F-FDG, 64Cu-ATSM and 18F-FLT) in a Dog with Fibrosarcoma: The Importance of Individualized Treatment Planning and Monitoring

    PubMed Central

    Zornhagen, Kamilla Westarp; Clausen, Malene M.; Hansen, Anders E.; Law, Ian; McEvoy, Fintan J.; Engelholm, Svend A.; Kjær, Andreas; Kristensen, Annemarie T.

    2015-01-01

    Glycolysis, hypoxia, and proliferation are important factors in the tumor microenvironment contributing to treatment-resistant aggressiveness. Imaging these factors using combined functional positron emission tomography and computed tomography can potentially guide diagnosis and management of cancer patients. A dog with fibrosarcoma was imaged using 18F-FDG, 64Cu-ATSM, and 18F-FLT before, during, and after 10 fractions of 4.5 Gy radiotherapy. Uptake of all tracers decreased during treatment. Fluctuations in 18F-FDG and 18F-FLT PET uptakes and a heterogeneous spatial distribution of the three tracers were seen. Tracer distributions partially overlapped. It appears that each tracer provides distinct information about tumor heterogeneity and treatment response. PMID:26854160

  8. Use of Molecular Imaging Markers of Glycolysis, Hypoxia and Proliferation ((18)F-FDG, (64)Cu-ATSM and (18)F-FLT) in a Dog with Fibrosarcoma: The Importance of Individualized Treatment Planning and Monitoring.

    PubMed

    Zornhagen, Kamilla Westarp; Clausen, Malene M; Hansen, Anders E; Law, Ian; McEvoy, Fintan J; Engelholm, Svend A; Kjær, Andreas; Kristensen, Annemarie T

    2015-01-01

    Glycolysis, hypoxia, and proliferation are important factors in the tumor microenvironment contributing to treatment-resistant aggressiveness. Imaging these factors using combined functional positron emission tomography and computed tomography can potentially guide diagnosis and management of cancer patients. A dog with fibrosarcoma was imaged using (18)F-FDG, (64)Cu-ATSM, and (18)F-FLT before, during, and after 10 fractions of 4.5 Gy radiotherapy. Uptake of all tracers decreased during treatment. Fluctuations in (18)F-FDG and (18)F-FLT PET uptakes and a heterogeneous spatial distribution of the three tracers were seen. Tracer distributions partially overlapped. It appears that each tracer provides distinct information about tumor heterogeneity and treatment response. PMID:26854160

  9. Hypoxia-activated prodrugs: paths forward in the era of personalised medicine

    PubMed Central

    Hunter, Francis W; Wouters, Bradly G; Wilson, William R

    2016-01-01

    Tumour hypoxia has been pursued as a cancer drug target for over 30 years, most notably using bioreductive (hypoxia-activated) prodrugs that target antineoplastic agents to low-oxygen tumour compartments. Despite compelling evidence linking hypoxia with treatment resistance and adverse prognosis, a number of such prodrugs have recently failed to demonstrate efficacy in pivotal clinical trials; an outcome that demands reflection on the discovery and development of these compounds. In this review, we discuss a clear disconnect between the pathobiology of tumour hypoxia, the pharmacology of hypoxia-activated prodrugs and the manner in which they have been taken into clinical development. Hypoxia-activated prodrugs have been evaluated in the manner of broad-spectrum cytotoxic agents, yet a growing body of evidence suggests that their activity is likely to be dependent on the coincidence of tumour hypoxia, expression of specific prodrug-activating reductases and intrinsic sensitivity of malignant clones to the cytotoxic effector. Hypoxia itself is highly variable between and within individual tumours and is not treatment-limiting in all cancer subtypes. Defining predictive biomarkers for hypoxia-activated prodrugs and overcoming the technical challenges of assaying them in clinical settings will be essential to deploying these agents in the era of personalised cancer medicine. PMID:27070712

  10. No Detectable Hypoxia in Malignant Salivary Gland Tumors: Preliminary Results

    SciTech Connect

    Wijffels, Karien; Hoogsteen, Ilse J.; Lok, Jasper; Rijken, Paulus F.J.W.; Marres, Henri A.M.; Wilde, Peter C.M. de; Kogel, Albert J. van der; Kaanders, Johannes H.A.M.

    2009-04-01

    Purpose: Hypoxia is detected in most solid tumors and is associated with malignant progression and adverse treatment outcomes. However, the oxygenation status of malignant salivary gland tumors has not been previously studied. The aim of this study was to investigate the potential clinical relevance of hypoxia in this tumor type. Methods and Materials: Twelve patients scheduled for surgical resection of a salivary gland tumor were preoperatively injected with the hypoxia marker pimonidazole and the proliferation marker iododeoxyuridine. Tissue samples of the dissected tumor were immunohistochemically stained for blood vessels, pimonidazole, carbonic anhydrase-IX, glucose transporters-1 and -3 (Glut-1, Glut-3), hypoxia-inducible factor-1{alpha}, iododeoxyuridine, and epidermal growth factor receptor. The tissue sections were quantitatively assessed by computerized image analysis. Results: The tissue material from 8 patients was of sufficient quality for quantitative analysis. All tumors were negative for pimonidazole binding, as well as for carbonic anhydrase-IX, Glut-1, Glut-3, and hypoxia-inducible factor-1{alpha}. The vascular density was high, with a median value of 285 mm{sup -2} (range, 209-546). The iododeoxyuridine-labeling index varied from <0.1% to 12.2% (median, 2.2%). Epidermal growth factor receptor expression levels were mostly moderate to high. In one-half of the cases, nuclear expression of epidermal growth factor receptor was observed. Conclusion: The absence of detectable pimonidazole binding, as well as the lack of expression of hypoxia-associated proteins in all tumors, indicates that malignant salivary gland tumors are generally well oxygenated. It is unlikely that hypoxia is a relevant factor for their clinical behavior and treatment responsiveness.

  11. Concepts in hypoxia reborn.

    PubMed

    Martin, Daniel S; Khosravi, Maryam; Grocott, Mike Pw; Mythen, Michael G

    2010-01-01

    The human fetus develops in a profoundly hypoxic environment. Thus, the foundations of our physiology are built in the most hypoxic conditions that we are ever likely to experience: the womb. This magnitude of exposure to hypoxia in utero is rarely experienced in adult life, with few exceptions, including severe pathophysiology in critical illness and environmental hypobaric hypoxia at high altitude. Indeed, the lowest recorded levels of arterial oxygen in adult humans are similar to those of a fetus and were recorded just below the highest attainable elevation on the Earth's surface: the summit of Mount Everest. We propose that the hypoxic intrauterine environment exerts a profound effect on human tolerance to hypoxia. Cellular mechanisms that facilitate fetal well-being may be amenable to manipulation in adults to promote survival advantage in severe hypoxemic stress. Many of these mechanisms act to modify the process of oxygen consumption rather than oxygen delivery in order to maintain adequate tissue oxygenation. The successful activation of such processes may provide a new chapter in the clinical management of hypoxemia. Thus, strategies employed to endure the relative hypoxia in utero may provide insights for the management of severe hypoxemia in adult life and ventures to high altitude may yield clues to the means by which to investigate those strategies. PMID:20727228

  12. Concepts in hypoxia reborn

    PubMed Central

    2010-01-01

    The human fetus develops in a profoundly hypoxic environment. Thus, the foundations of our physiology are built in the most hypoxic conditions that we are ever likely to experience: the womb. This magnitude of exposure to hypoxia in utero is rarely experienced in adult life, with few exceptions, including severe pathophysiology in critical illness and environmental hypobaric hypoxia at high altitude. Indeed, the lowest recorded levels of arterial oxygen in adult humans are similar to those of a fetus and were recorded just below the highest attainable elevation on the Earth's surface: the summit of Mount Everest. We propose that the hypoxic intrauterine environment exerts a profound effect on human tolerance to hypoxia. Cellular mechanisms that facilitate fetal well-being may be amenable to manipulation in adults to promote survival advantage in severe hypoxemic stress. Many of these mechanisms act to modify the process of oxygen consumption rather than oxygen delivery in order to maintain adequate tissue oxygenation. The successful activation of such processes may provide a new chapter in the clinical management of hypoxemia. Thus, strategies employed to endure the relative hypoxia in utero may provide insights for the management of severe hypoxemia in adult life and ventures to high altitude may yield clues to the means by which to investigate those strategies. PMID:20727228

  13. Carnosine pretreatment protects against hypoxia-ischemia brain damage in the neonatal rat model.

    PubMed

    Zhang, Xiangmin; Song, Lili; Cheng, Xiuyong; Yang, Yi; Luan, Bin; Jia, Liting; Xu, Falin; Zhang, Zhan

    2011-09-30

    Perinatal hypoxia-ischemia brain injury is a major cause of mortality and morbidity in neonates and lacks an effective treatment thus far. Carnosine has been demonstrated to play a neuroprotective role in the adult brain injuries. However, there is no information available concerning its neuroprotective role in the immature brains after hypoxia-ischemia insults. Therefore, we investigated whether carnosine could also confer neuroprotective effects in a neonatal rat hypoxia-ischemia model. Hypoxia-ischemia was induced in rats on postnatal day 7 (P7). Carnosine (250 mg/kg) was administered intraperitoneally, 30 min prior to hypoxia-ischemia induction. Morphological brain injury and biochemical markers of apoptosis and oxidative stress were evaluated 24 h after hypoxia-ischemia induction. Cognitive performance was evaluated by the Morris Water Maze test on P28-P33. We found that pretreatment with carnosine significantly reduced the infarct volume and the number of terminal-deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cells in the hypoxia-ischemia brain. Carnosine also inhibited mRNA expression of apoptosis-inducing factor(AIF) and caspase-3, which was accompanied by an increase in superoxide dismutase(SOD)activity and a decrease in the malondialdehyde(MDA)level in carnosine-treated rats. Furthermore, carnosine also improved the spatial learning and memory abilities of rats declined due to hypoxia-ischemia. These results demonstrate that carnosine can protect rats against hypoxia-ischemia-induced brain damage by antioxidation. PMID:21693116

  14. Hypoxia and spermatogenesis.

    PubMed

    Jankovic Velickovic, Ljubinka; Stefanovic, Vladisav

    2014-05-01

    This review mainly focuses on our understanding of spermatogenesis in physiological and pathological hypoxic condition. Real hypoxia is closely related to vascular changes and an increase in testicular temperature. Both induce a reduction in sperm count and can be related to the increase in germ cell apoptosis. On the other hand, change in the temperature, and oxygen levels in the microenvironment have influence on spermatogonial stem cell function and differentiation. The initial connection between hypoxia and a factor critical for stem cell maintenance is alteration in Oct-4 expression, and these data may be a useful strategy for modulating stem cell function. Unilateral testicular ischemia-induced cell death can be accompanied by an increase in germ cell apoptosis in the contralateral testis. The injury of contralateral testis following unilateral testicular damage is controversial, and it can contribute to the reduction in fertility. PMID:24265038

  15. Intermittent hypoxia and neurorehabilitation.

    PubMed

    Gonzalez-Rothi, Elisa J; Lee, Kun-Ze; Dale, Erica A; Reier, Paul J; Mitchell, Gordon S; Fuller, David D

    2015-12-15

    In recent years, it has become clear that brief, repeated presentations of hypoxia [i.e., acute intermittent hypoxia (AIH)] can boost the efficacy of more traditional therapeutic strategies in certain cases of neurologic dysfunction. This hypothesis derives from a series of studies in animal models and human subjects performed over the past 35 yr. In 1980, Millhorn et al. (Millhorn DE, Eldridge FL, Waldrop TG. Respir Physiol 41: 87-103, 1980) showed that electrical stimulation of carotid chemoafferent neurons produced a persistent, serotonin-dependent increase in phrenic motor output that outlasts the stimulus for more than 90 min (i.e., a "respiratory memory"). AIH elicits similar phrenic "long-term facilitation" (LTF) by a mechanism that requires cervical spinal serotonin receptor activation and de novo protein synthesis. From 2003 to present, a series of studies demonstrated that AIH can induce neuroplasticity in the injured spinal cord, causing functional recovery of breathing capacity after cervical spinal injury. Subsequently, it was demonstrated that repeated AIH (rAIH) can induce recovery of limb function, and the functional benefits of rAIH are greatest when paired with task-specific training. Since uncontrolled and/or prolonged intermittent hypoxia can elicit pathophysiology, a challenge of intermittent hypoxia research is to ensure that therapeutic protocols are well below the threshold for pathogenesis. This is possible since many low dose rAIH protocols have induced functional benefits without evidence of pathology. We propose that carefully controlled rAIH is a safe and noninvasive modality that can be paired with other neurorehabilitative strategies including traditional activity-based physical therapy or cell-based therapies such as intraspinal transplantation of neural progenitors. PMID:25997947

  16. Geometric intrinsic symmetries

    SciTech Connect

    Gozdz, A. Szulerecka, A.; Pedrak, A.

    2013-08-15

    The problem of geometric symmetries in the intrinsic frame of a many-body system (nucleus) is considered. An importance of symmetrization group notion is discussed. Ageneral structure of the intrinsic symmetry group structure is determined.

  17. Follicle-stimulating Hormone Activation of Hypoxia-inducible Factor-1 by the Phosphatidylinositol 3-Kinase/AKT/Ras Homolog Enriched in Brain (Rheb)/Mammalian Target of Rapamycin (mTOR) Pathway Is Necessary for Induction of Select Protein Markers of Follicular Differentiation*

    PubMed Central

    Alam, Hena; Maizels, Evelyn T.; Park, Youngkyu; Ghaey, Shail; Feiger, Zachary J.; Chandel, Navdeep S.; Hunzicker-Dunn, Mary

    2006-01-01

    We sought to elucidate the role of AKT in follicle-stimulating hormone (FSH)-mediated granulosa cell (GC) differentiation. Our results define a signaling pathway in GCs whereby the inactivating phosphorylation of tuberin downstream of phosphatidylinositol (PI) 3-kinase/AKT activity leads to Rheb (Ras homolog enriched in brain) and subsequent mTOR (mammalian target of rapamycin) activation. mTOR then stimulates translation by phosphorylating p70 S6 kinase and, consequently, the 40 S ribosomal protein S6. Activation of this pathway is required for FSH-mediated induction of several follicular differentiation markers, including luteinizing-hormone receptor (LHR), inhibin-α, microtubule-associated protein 2D, and the PKA type IIβ regulatory subunit. FSH also promotes activation of the transcription factor hypoxia-inducible factor-1 (HIF-1). FSH-stimulated HIF-1 activity is inhibited by the PI 3-kinase inhibitor LY294002, the Rheb inhibitor FTI-277 (farne-syltransferase inhibitor-277), and the mTOR inhibitor rapamycin. Finally, we find that the FSH-mediated up-regulation of reporter activities for LHR, inhibin-α, and vascular endothelial growth factor is dependent upon HIF-1 activity, because a dominant negative form of HIF-1α interferes with the up-regulation of these genes. These results show that FSH enhances HIF-1 activity downstream of the PI 3-kinase/AKT/Rheb/mTOR pathway in GCs and that HIF-1 activity is necessary for FSH to induce multiple follicular differentiation markers. PMID:14982927

  18. Hypoxia and fetal heart development.

    PubMed

    Patterson, A J; Zhang, L

    2010-10-01

    Fetal hearts show a remarkable ability to develop under hypoxic conditions. The metabolic flexibility of fetal hearts allows sustained development under low oxygen conditions. In fact, hypoxia is critical for proper myocardial formation. Particularly, hypoxia inducible factor 1 (HIF-1) and vascular endothelial growth factor play central roles in hypoxia-dependent signaling in fetal heart formation, impacting embryonic outflow track remodeling and coronary vessel growth. Although HIF is not the only gene involved in adaptation to hypoxia, its role places it as a central figure in orchestrating events needed for adaptation to hypoxic stress. Although "normal" hypoxia (lower oxygen tension in the fetus as compared with the adult) is essential in heart formation, further abnormal hypoxia in utero adversely affects cardiogenesis. Prenatal hypoxia alters myocardial structure and causes a decline in cardiac performance. Not only are the effects of hypoxia apparent during the perinatal period, but prolonged hypoxia in utero also causes fetal programming of abnormality in the heart's development. The altered expression pattern of cardioprotective genes such as protein kinase c epsilon, heat shock protein 70, and endothelial nitric oxide synthase, likely predispose the developing heart to increased vulnerability to ischemia and reperfusion injury later in life. The events underlying the long-term changes in gene expression are not clear, but likely involve variation in epigenetic regulation. PMID:20712587

  19. Temporal Onset of Hypoxia and Oxidative Stress After Pulmonary Irradiation

    SciTech Connect

    Fleckenstein, Katharina; Zgonjanin, Larisa; Chen Liguang; Rabbani, Zahid; Jackson, Isabel L.; Thrasher, Bradley; Kirkpatrick, John; Foster, W. Michael; Vujaskovic, Zeljko . E-mail: vujas@radonc.duke.edu

    2007-05-01

    Purpose: To investigate the temporal onset of hypoxia following irradiation, and to show how it relates to pulmonary vascular damage, macrophage accumulation, and the production of reactive oxygen species and cytokines. Our previous studies showed that tissue hypoxia in the lung after irradiation contributed to radiation-induced injury. Methods and Materials: Female Fisher 344 rats were irradiated to the right hemithorax with a single dose of 28 Gy. Serial studies were performed up to 20 weeks following irradiation. Radionuclide lung-perfusion studies were performed to detect changes in pulmonary vasculature. Immunohistochemical studies were conducted to study macrophages, tissue hypoxia (carbonic anhydrase-9 marker), oxidative stress (8-hydroxy-2'-deoxyguanosine), and the expression of profibrogenic (transforming growth factor-{beta} [TGF-{beta}]) and proangiogenic (vascular endothelial growth factor [VEGF]) cytokines. Results: Significant changes in lung perfusion along with tissue hypoxia were observed 3 days after irradiation. Significant oxidative stress was detected 1 week after radiation, whereas macrophages started to accumulate at 4 weeks. A significant increase in TGF-{beta} expression was seen within 1 day after radiation, and for VEGF at 2 weeks after radiation. Levels of hypoxia, oxidative stress, and both cytokines continued to rise with time after irradiation. The steepest increase correlated with vast macrophage accumulation. Conclusions: Early changes in lung perfusion, among other factors initiate, the development of hypoxia and chronic oxidative stress after irradiation. Tissue hypoxia is associated with a significant increase in the activation of macrophages and their continuous production of reactive oxygen species, stimulating the production of fibrogenic and angiogenic cytokines, and maintaining the development of chronic radiation-induced lung injury.

  20. Hypoxia promotes vasculogenic mimicry formation by the Twist1-Bmi1 connection in hepatocellular carcinoma.

    PubMed

    Liu, Kun; Sun, Baocun; Zhao, Xiulan; Wang, Xudong; Li, Yanlei; Qiu, Zhiqiang; Liu, Tieju; Gu, Qiang; Dong, Xueyi; Zhang, Yanhui; Wang, Yong; Zhao, Nan

    2015-09-01

    Aggressive tumor cells can mimic embryonic vasculogenic networks and form vasculogenic mimicry (VM). Preliminary studies demonstrated that hypoxia can promote VM formation; however, the underlying mechanism remains unclear. The present study aimed to investigate the role of the Twist1‑Bmi1 connection in hypoxia‑induced VM formation and the underlying mechanism. In the in vitro experiments, western blot analysis demonstrated that hypoxia upregulated the expression of Twist1, Bmi1, epithelial‑mesenchymal transition (EMT) markers, stem cell markers and VM‑associated markers. The 3D culture assay showed that hypoxia promoted VM formation in hepatocellular carcinoma (HCC) cell lines. Using transfection and in vitro cell experiments, the Twist1‑Bmi1 connection was confirmed to have an important role in inducing EMT, cell stemness and VM formation. In the in vivo experiments, the murine hypoxia models were established via incomplete femoral artery ligation and the mechanism by which hypoxia promoted Twist1 and Bmi1 expression and led to VM formation was demonstrated by immunohistochemistry staining and endomucin/periodic acid Schiff double‑staining. In conclusion, hypoxia upregulate the expression of Twist1 and Bmi1, and these two proteins have an important role in inducing EMT and cancer cell stemness, which contributed to VM formation. PMID:26202447

  1. Differences in in vitro cerebellar neuronal responses to hypoxia in eider ducks, chicken and rats.

    PubMed

    Ludvigsen, Stian; Folkow, Lars P

    2009-11-01

    Ducks are well-known to be more tolerant to asphyxia than non-diving birds, but it is not known if their defences include enhanced neuronal hypoxia tolerance. To test this, we compared extracellular recordings of spontaneous activity in the Purkinje cell layer of 400 mum thick isolated cerebellar slices from eider ducks, chickens and rats, before, during and after 60 min hypoxia (95%N(2)-5%CO(2)) or chemical anoxia (hypoxia + 2 mM NaCN). Most slices rapidly lost activity in hypoxia, with or without recovery after rinse and return to normoxia (95%O(2)-5%CO(2)), but some maintained spontaneous activity throughout the insult. Proportions of 'surviving' (i.e. recovering or active) duck slices were significantly higher than for chickens in anoxia, and relative activity levels were higher for ducks than for chickens during hypoxia, anoxia and recovery. Survival of rat slices was significantly poorer than for birds under all conditions. Results suggest that (1) duck cerebellar neurons are intrinsically more hypoxia-tolerant than chicken neurons; (2) avian neurons are more hypoxia-tolerant than rat neurons, and (3) the enhanced hypoxic tolerance of duck neurons largely depended on efficient anaerobiosis since it mainly manifested itself in chemical anoxia. Mechanisms underlying the observed differences in neuronal hypoxic responses remain to be elucidated. PMID:19779726

  2. Adipogenesis, lipogenesis and lipolysis is stimulated by mild but not severe hypoxia in 3T3-L1 cells.

    PubMed

    Weiszenstein, Martin; Musutova, Martina; Plihalova, Andrea; Westlake, Katerina; Elkalaf, Moustafa; Koc, Michal; Prochazka, Antonin; Pala, Jan; Gulati, Sumeet; Trnka, Jan; Polak, Jan

    2016-09-16

    In-vitro investigation of the effects of hypoxia is limited by physical laws of gas diffusion and cellular O2 consumption, making prolonged exposures to stable O2 concentrations impossible. Using a gas-permeable cultureware, chronic effects of mild and severe hypoxia on triglyceride accumulation, lipid droplet size distribution, spontaneous lipolysis and gene expression of adipocyte-specific markers were assessed. 3T3-L1 cells were differentiated under 20%, 4% or 1% O2 using a gas-permeable cultureware. Triglyceride accumulation, expression of genes characteristic for advanced adipocyte differentiation and involvement of key lipogenesis enzymes were assessed after exposures. Lipogenesis increased by 375% under mild hypoxia, but dropped by 43% in severe hypoxia. Mild, but not severe, hypoxia increased formation of large lipid droplets 6.4 fold and strongly induced gene expression of adipocyte-specific markers. Spontaneous lipolysis increased by 488% in mild, but only by 135% in severe hypoxia. Inhibition of ATP-dependent citrate lyase suppressed hypoxia-induced lipogenesis by 81% and 85%. Activation of HIF inhibited lipogenesis by 59%. Mild, but not severe, hypoxia stimulates lipolysis and promotes adipocyte differentiation, probably through excess of acetyl-CoA originating from tricarboxylic acid cycle independently of HIF activation. PMID:27498031

  3. Marker development

    SciTech Connect

    Adams, M.R.

    1987-05-01

    This report is to discuss the marker development for radioactive waste disposal sites. The markers must be designed to last 10,000 years, and place no undue burdens on the future generations. Barriers cannot be constructed that preclude human intrusion. Design specifications for surface markers will be discussed, also marker pictograms will also be covered.

  4. Expression of miR-210 in relation to other measures of hypoxia and prediction of benefit from hypoxia modification in patients with bladder cancer

    PubMed Central

    Irlam-Jones, J J; Eustace, A; Denley, H; Choudhury, A; Harris, A L; Hoskin, P J; West, C M L

    2016-01-01

    Background: The addition of hypoxia modifiers carbogen and nicotinamide (CON) to radiotherapy (RT) improved overall survival (OS) in bladder cancer patients in the BCON phase III clinical trial. We investigate whether expression of hsa-miR-210 in BCON patient samples reflects hypoxia and predicts benefit from hypoxia modification. Methods: In all, 183 T1–T4a bladder cancer samples were available for miR-210 analysis. A total of 86 received RT+CON and 97 received RT alone. TaqMan qPCR plates were used to assess miR-210 expression. Patients were classified as low (hypoxia biomarkers were available for comparison. Results: Patients with high miR-210 had a trend towards improved 5-year OS with RT+CON (53.2%) compared with RT alone (37.8% hazard ratio (HR) 1.68, 95% CI 0.95–2.95, P=0.07). No benefit was seen with low miR-210 (HR 1.02, 95% CI 0.58–1.79, P=0.97). High miR-210 was significantly associated with high HIF-1α protein (P=0.001), CA9 protein (P=0.0004), Glut-1 protein (P=0.001), 26-gene hypoxia score (P=0.007), tumour necrosis (P=0.02) and concurrent pTis (P=0.03). Conclusions: High miR-210 may reflect hypoxia in bladder cancer. However, its ability to predict benefit from hypoxia modification does not improve upon other hypoxia markers. Investigation as part of a miRNA hypoxia signature may reveal the full potential of miR-210. PMID:27441495

  5. Modeling the Spatial Distribution of Chronic Tumor Hypoxia: Implications for Experimental and Clinical Studies

    PubMed Central

    Powathil, Gibin; Kohandel, Mohammad; Milosevic, Michael; Sivaloganathan, Siv

    2012-01-01

    Tumor oxygenation status is considered one of the important prognostic markers in cancer since it strongly influences the response of cancer cells to various treatments; in particular, to radiation therapy. Thus, a proper and accurate assessment of tumor oxygen distribution before the treatment may highly affect the outcome of the treatment. The heterogeneous nature of tumor hypoxia, mainly influenced by the complex tumor microenvironment, often makes its quantification very difficult. The usual methods used to measure tumor hypoxia are biomarkers and the polarographic needle electrode. Although these techniques may provide an acceptable assessment of hypoxia, they are invasive and may not always give a spatial distribution of hypoxia, which is very useful for treatment planning. An alternative method to quantify the tumor hypoxia is to use theoretical simulations with the knowledge of tumor vasculature. The purpose of this paper is to model tumor hypoxia using a known spatial distribution of tumor vasculature obtained from image data, to analyze the accuracy of polarographic needle electrode measurements in quantifying hypoxia, to quantify the optimum number of measurements required to satisfactorily evaluate the tumor oxygenation status, and to study the effects of hypoxia on radiation response. Our results indicate that the model successfully generated an accurate oxygenation map for tumor cross-sections with known vascular distribution. The method developed here provides a way to estimate tumor hypoxia and provides guidance in planning accurate and effective therapeutic strategies and invasive estimation techniques. Our results agree with the previous findings that the needle electrode technique gives a good estimate of tumor hypoxia if the sampling is done in a uniform way with 5-6 tracks of 20–30 measurements each. Moreover, the analysis indicates that the accurate measurement of oxygen profile can be very useful in determining right radiation doses to the

  6. Modulatory effects of seabuckthorn (Hippophae rhamnoides L.) in hypobaric hypoxia induced cerebral vascular injury.

    PubMed

    Purushothaman, Jayamurthy; Suryakumar, Geetha; Shukla, Dhananjay; Malhotra, Anand Swaroop; Kasiganesan, Harinath; Kumar, Ratan; Sawhney, Ramesh Chand; Chami, Arumughan

    2008-11-25

    Cerebral edema caused by vascular leakage is a major problem in various injuries of the CNS, such as stroke, head injury and high-altitude illness. A common feature of all these disorders is the fact that they are associated with tissue hypoxia. Hypoxia has been suggested to be a major pathogenic factor for the induction of vascular leakage in the brain. The objective of the present study was to evaluate potential of seabuckthorn (SBT) (Hippophae rhamnoides L.) seed oil in curtailing hypoxia induced transvascular fluid leakage in brain of hypoxia-exposed rats. Exposure of animals to hypobaric hypoxia (9144 m, 5h) caused a significant increase in the transvascular leakage studied by measuring water content and leakage of sodium fluorescein dye in the brain. Hypoxic stress also significantly enhanced the oxidative stress markers such as free radicals and malondialdehyde and it accompanied with decreased levels of antioxidants such as glutathione, glutathione peroxidase and superoxide dismutase. Pretreatment of animals with SBT seed oil significantly restricted the hypoxia induced increase in fluorescein dye leakage suggesting protection against hypoxia induced transvascular leakage in the brain. Hypoxia induced increase in the levels of free radicals and malondialdehyde were significantly lowered after SBT pretreatment. The SBT seed oil pretreatment also resulted in the significantly improved hypoxic tolerance as evidenced by increased hypoxic gasping time and survival time and decreased plasma catecholamine levels, as compared to hypoxic animals. These observations suggest that SBT seed oil possesses significant hypoxia protection activity and curtailed hypoxia induced enhanced vascular leakage in the brain. PMID:18824077

  7. Hypoxia promotes thyroid differentiation of native murine induced pluripotent stem cells.

    PubMed

    Yang, Yipeng; Lu, Yunshu; Chen, Tong; Zhang, Shenglai; Chu, Bingfeng; Gong, Yurong; Zhao, Weixin; Zhu, Jian; Liu, Yingbin

    2016-01-01

    Hypothyroidism is a very common hormonal deficiency and the stem cell technology which developed in the recent years may offer a therapeutic strategy for treating this disorder. Hypoxia has been demonstrated to play an important role in embryonic formation and development and to modulate stem cell differentiation. However, the influence of oxygen tension on thyroid differentiation has not been studied. In this study, we used murine induced pluripotent stem (iPS) cells for thyroid cell differentiation under normoxic and hypoxic conditions and compared differentiation efficiency in morphology, function, gene and protein expression under both conditions. We found that hypoxia promoted adhesion and outgrowth of embryoid bodies (EBs) derived from murine iPS cells. Expression of endodermal markers (Foxa2 and Gata4) and thyroid transcription factors (Pax8 and Nkx2.1) was increased by hypoxia at both gene and protein levels during early-mid differentiation stages (p<0.05). And so were the thyroid specific markers NIS and TSHR at the end of the experiment (p<0.05). In addition, functional iodide uptake by differentiated cells was also increased after hypoxia. Thyroid differentiation from iPS cells is enhanced under hypoxia and this may involve hypoxia inducible factors (HIFs) and their downstream gene FGF2. Our data offer a foundation for understanding thyroid development and provide a potentially more efficient way to use cell therapy for treating thyroid deficiency. PMID:27389981

  8. Autophagy-Associated Atrophy and Metabolic Remodeling of the Mouse Diaphragm after Short-Term Intermittent Hypoxia

    PubMed Central

    Giordano, Christian; Lemaire, Christian; Li, Tong; Kimoff, R. John; Petrof, Basil J.

    2015-01-01

    Background Short-term intermittent hypoxia (IH) is common in patients with acute respiratory disorders. Although prolonged exposure to hypoxia induces atrophy and increased fatigability of skeletal muscle, the response to short-term IH is less well known. We hypothesized that the diaphragm and limb muscles would adapt differently to short-term IH given that hypoxia stimulates ventilation and triggers a superimposed exercise stimulus in the diaphragm. Methods We determined the structural, metabolic, and contractile properties of the mouse diaphragm after 4 days of IH (8 hours per day, 30 episodes per hour to a FiO2 nadir=6%), and compared responses in the diaphragm to a commonly studied reference limb muscle, the tibialis anterior. Outcome measures included muscle fiber size, assays of muscle proteolysis (calpain, ubiquitin-proteasome, and autophagy pathways), markers of oxidative stress and mitochondrial function, quantification of intramyocellular lipid and lipid metabolism genes, type I myosin heavy chain (MyHC) expression, and in vitro contractile properties. Results After 4 days of IH, the diaphragm alone demonstrated significant atrophy (30% decrease of myofiber size) together with increased LC3B-II protein (2.4-fold) and mRNA markers of the autophagy pathway (LC3B, Gabarapl1, Bnip3), whereas active calpain and E3 ubiquitin ligases (MuRF1, atrogin-1) were unaffected in both muscles. Succinate dehydrogenase activity was significantly reduced by IH in both muscles. However, only the diaphragm exhibited increased intramyocellular lipid droplets (2.5-fold) after IH, along with upregulation of genes linked to activated lipid metabolism. In addition, although the diaphragm showed evidence for acute fatigue immediately following IH, it underwent an adaptive fiber type switch toward slow type I MyHC-expressing fibers, associated with greater intrinsic endurance of the muscle during repetitive stimulation in vitro. Conclusions Short-term IH induces preferential atrophy

  9. Hypoxia, Oxidative Stress and Fat.

    PubMed

    Netzer, Nikolaus; Gatterer, Hannes; Faulhaber, Martin; Burtscher, Martin; Pramsohler, Stephan; Pesta, Dominik

    2015-01-01

    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. PMID:26061760

  10. Detecting changes in tumor hypoxia with carbonic anhydrase IX and pimonidazole.

    PubMed

    Shin, Kyung Hwan; Diaz-Gonzalez, Juan A; Russell, James; Chen, Qing; Burgman, Paul; Li, Xiao-Feng; Ling, C Clifton

    2007-01-01

    We have used immunohistochemistry to examine the dynamics of tumor hypoxia.. Expression of CAIX is known to be influenced by tumor hypoxia, and this protein has been shown to be an endogenous hypoxia marker in several models. However, due to its long half-life, it could also be present in oxygenated tissue that had recently been hypoxic. To investigate this issue we have compared CAIX expression to the exogenous hypoxia marker, pimonidazole using HT29 (human colorectal cancer) xenografts. We manipulated tumor hypoxia with carbogen and hydralazine, treatments that respectively increased and decreased tumor oxygenation. (Carbogen was given 75 minutes and hydralazine 30 minutes before sacrifice). In tumors from the control group, CAIX and pimonidazole exhibited similar (though not identical) spatial distribution, and for both markers, the fraction of the section staining positively was similar (13.2% and 12.6% respectively). The mice treated with hydralazine showed a significant increase in pimonidazole accumulation (37.2%, p = 0.03), though the CAIX positive fraction was unchanged (14.2%). In contrast, in the carbogen group pimonidazole staining decreased to 3% (p = 0.01) though CAIX expression was again unaltered. These results suggest that comparison of CAIX and pimonidazole will allow for the detection of reoxygenation. PMID:17172824

  11. Alterations in Skeletal Muscle Oxidative Phenotype in Mice Exposed to 3 Weeks of Normobaric Hypoxia.

    PubMed

    Slot, Ilse G M; Schols, Annemie M W J; de Theije, Chiel C; Snepvangers, Frank J M; Gosker, Harry R

    2016-02-01

    Skeletal muscle of patients with chronic respiratory failure is prone to loss of muscle mass and oxidative phenotype. Tissue hypoxia has been associated with cachexia and emphysema in humans. Experimental research on the role of hypoxia in loss of muscle oxidative phenotype, however, has yielded inconsistent results. Animal studies are frequently performed in young animals, which may hinder translation to generally older aged patients. Therefore, in this study, we tested the hypothesis that hypoxia induces loss of skeletal muscle oxidative phenotype in a model of aged (52 weeks) mice exposed to 3 weeks of hypoxia. Additional groups of young (4 weeks) and adult (12 weeks) mice were included to examine age effects. To verify hypoxia-induced cachexia, fat pad and muscle weights as well as muscle fiber cross-sectional areas were determined. Muscle oxidative phenotype was assessed by expression and activity of markers of mitochondrial metabolism and fiber-type distribution. A profound loss of muscle and fat was indeed accompanied by a slightly lower expression of markers of muscle oxidative capacity in the aged hypoxic mice. In contrast, hypoxia-associated changes of fiber-type composition were more prominent in the young mice. The differential response of the muscle of young, adult, and aged mice to hypoxia suggests that age matters and that the aged mouse is a better model for translation of findings to elderly patients with chronic respiratory disease. Furthermore, the findings warrant further mechanistic research into putative accelerating effects of hypoxia-induced loss of oxidative phenotype on the cachexia process in chronic respiratory disease. PMID:26129845

  12. Bone Markers

    MedlinePlus

    ... Alkaline Phosphatase; Osteocalcin; P1NP; Procollagen Type 1 N-Terminal Propeptide Formal name: Biochemical Markers of Bone Remodeling ... tests for evaluating bone turnover: C-telopeptide (C-terminal telopeptide of type 1 collagen (CTx)) – a marker ...

  13. [Classification of hypoxia, hypo-, and hypercapnia].

    PubMed

    Agadzhanian, N A; Chizhov, A Ia

    2003-01-01

    The new classifications of hypoxical, hypo- and hypercapnical conditions are elaborated. They take into account the ecological factors in the development of various kinds of exogenic hypoxia, hypercapnia. For the first time the positive sides of physiological hypoxia and hypercapnia are brought in. In all classification til the last days hypoxia was considered as pathological process only. However hypoxia can be met in different physiologic conditions of organism: internal period of fetus development, hard physical work, increased sportsmen activity, hypoxia after hearty meal, hypoxia of aged organism. The same it is possible to say about the hypo- and hypercapnical conditions. PMID:12918246

  14. Betaine reduces the expression of inflammatory adipokines caused by hypoxia in human adipocytes.

    PubMed

    Olli, K; Lahtinen, S; Rautonen, N; Tiihonen, K

    2013-01-14

    Obesity is characterised by a state of chronic low-grade inflammation and the elevated circulating and tissue levels of inflammatory markers, including inflammation-related adipokines, released from white adipose tissue. The expression and release of these adipokines generally rises as the adipose tissue expands and hypoxic conditions start to develop within the tissue. Here, the effect of betaine, a trimethylglycine having a biological role as an osmolyte and a methyl donor, on the expression of inflammation-related markers was tested in human adipocytes under hypoxia. Differentiated adipocytes were cultivated under low (1 %) oxygen tension for 8-20 h. The expression of different adipokines, including IL-6, leptin, PPARγ, TNF-α and adiponectin, was measured by quantitative PCR by determining the relative mRNA level from the adipocytes. Hypoxia, in general, led to a decrease in the expression of PPARγ mRNA in human adipocytes, whereas the expression levels of leptin and IL-6 mRNA were substantially increased by hypoxia. The cultivation of adipocytes under hypoxia also led to a reduction in the expression of TNF-α mRNA. The results showed that hypoxia increased the relative quantification of leptin gene transcription, and that betaine (250 μmol/l) reduced this effect, caused by low oxygen conditions. Under hypoxia, betaine also reduced the mRNA level of the pro-inflammatory markers IL-6 and TNF-α. These results demonstrate that the extensive changes in the expression of inflammation-related adipokines in human adipocytes caused by hypoxia can be diminished by the presence of physiologically relevant concentrations of betaine. PMID:22424556

  15. Hypoxia-inducible factor 1 and cardiovascular disease.

    PubMed

    Semenza, Gregg L

    2014-01-01

    Cardiac function is required for blood circulation and systemic oxygen delivery. However, the heart has intrinsic oxygen demands that must be met to maintain effective contractility. Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that functions as a master regulator of oxygen homeostasis in all metazoan species. HIF-1 controls oxygen delivery, by regulating angiogenesis and vascular remodeling, and oxygen utilization, by regulating glucose metabolism and redox homeostasis. Analysis of animal models suggests that by activation of these homeostatic mechanisms, HIF-1 plays a critical protective role in the pathophysiology of ischemic heart disease and pressure-overload heart failure. PMID:23988176

  16. Hypoxia-Inducible Factor 1 and Cardiovascular Disease

    PubMed Central

    Semenza, Gregg L.

    2015-01-01

    Cardiac function is required for blood circulation and systemic oxygen delivery. However, the heart has intrinsic oxygen demands that must be met to maintain effective contractility. Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that functions as a master regulator of oxygen homeostasis in all metazoan species. HIF-1 controls oxygen delivery, by regulating angiogenesis and vascular remodeling, and oxygen utilization, by regulating glucose metabolism and redox homeostasis. Analysis of animal models suggests that by activation of these homeostatic mechanisms, HIF-1 plays a critical protective role in the pathophysiology of ischemic heart disease and pressure-overload heart failure. PMID:23988176

  17. Imaging Tumor Hypoxia to Advance Radiation Oncology

    PubMed Central

    Lee, Chen-Ting; Boss, Mary-Keara

    2014-01-01

    Abstract Significance: Most solid tumors contain regions of low oxygenation or hypoxia. Tumor hypoxia has been associated with a poor clinical outcome and plays a critical role in tumor radioresistance. Recent Advances: Two main types of hypoxia exist in the tumor microenvironment: chronic and cycling hypoxia. Chronic hypoxia results from the limited diffusion distance of oxygen, and cycling hypoxia primarily results from the variation in microvessel red blood cell flux and temporary disturbances in perfusion. Chronic hypoxia may cause either tumor progression or regressive effects depending on the tumor model. However, there is a general trend toward the development of a more aggressive phenotype after cycling hypoxia. With advanced hypoxia imaging techniques, spatiotemporal characteristics of tumor hypoxia and the changes to the tumor microenvironment can be analyzed. Critical Issues: In this review, we focus on the biological and clinical consequences of chronic and cycling hypoxia on radiation treatment. We also discuss the advanced non-invasive imaging techniques that have been developed to detect and monitor tumor hypoxia in preclinical and clinical studies. Future Directions: A better understanding of the mechanisms of tumor hypoxia with non-invasive imaging will provide a basis for improved radiation therapeutic practices. Antioxid. Redox Signal. 21, 313–337. PMID:24329000

  18. Regulation of tyrosine hydroxylase gene expression in the rat carotid body by hypoxia.

    PubMed

    Czyzyk-Krzeska, M F; Bayliss, D A; Lawson, E E; Millhorn, D E

    1992-04-01

    The activity (Vmax) of tyrosine hydroxylase (TH; EC 1.14.16.2), the rate limiting enzyme in the synthesis of catecholamines, is increased in carotid body, superior cervical ganglion, and the adrenal medulla during hypoxia (i.e., reduced PaO2). The present study was undertaken to determine if the increase in TH activity in these tissues during hypoxia is regulated at the level of TH mRNA. Adult rats were exposed to hypoxia (10% O2) or room air for periods lasting from 1 to 48 h. The carotid bodies, superior cervical ganglia, and adrenals were removed and processed for in situ hybridization using 35S-labeled oligonucleotide probes. The concentration of TH mRNA was increased by hypoxia at all time points in carotid body type I cells, but not in cells of either superior cervical ganglion or adrenal medulla. The increase in TH mRNA in carotid body during hypoxia did not require innervation of the carotid body or intact adrenal glands. In addition, hypercapnia, another physiological stimulus of carotid body activity, failed to induce an increase in TH mRNA in type I cells. Our findings suggest that hypoxia stimulates TH gene expression in the carotid body by a mechanism that is intrinsic to type I cells. PMID:1347783

  19. Hypoxia-mediated tumour targeting.

    PubMed

    Binley, K; Askham, Z; Martin, L; Spearman, H; Day, D; Kingsman, S; Naylor, S

    2003-04-01

    Hypoxia is a common physiological feature of tumours. It activates a signalling cascade that culminates in the stabilization of the HIF-1 transcription factor and activation of genes that possess a hypoxia response element (HRE). We have used an optimized hypoxia responsive promoter (OBHRE) to investigate hypoxia-targeted gene expression in vivo in the context of an adenovirus vector. The OBHRE promoter showed limited activity in the liver or spleen such that expression was 1000-fold lower than that driven by the strong CMV/IE promoter. However, in the context of the tumour microenvironment, the OBHRE promoter achieved expression levels comparable to that of the CMV/IE promoter. Next, we showed that an adenovirus expressing the human cytochrome P450 (CYP2B6) regulated by the OBHRE promoter delays tumour growth in response to the prodrug cyclophosphamide (CPA). Finally, we exploited the hepatotropism of adenovirus to investigate whether the OBHRE promoter could mitigate the hepatotoxicity of a recombinant adenovirus expressing thymidine kinase (TK) in the context of the prodrug ganciclovir (GCV). High-dose Ad.CMVTK/GCV treatment caused significant liver necrosis whereas the same dose of Ad.HRETK was well tolerated. These in vivo data demonstrate that hypoxia-targeted gene expression via the OBHRE promoter can be used to increase the therapeutic window of cytotoxic cancer gene therapy. PMID:12646859

  20. Lung Oxidative Damage by Hypoxia

    PubMed Central

    Araneda, O. F.; Tuesta, M.

    2012-01-01

    One of the most important functions of lungs is to maintain an adequate oxygenation in the organism. This organ can be affected by hypoxia facing both physiological and pathological situations. Exposure to this condition favors the increase of reactive oxygen species from mitochondria, as from NADPH oxidase, xanthine oxidase/reductase, and nitric oxide synthase enzymes, as well as establishing an inflammatory process. In lungs, hypoxia also modifies the levels of antioxidant substances causing pulmonary oxidative damage. Imbalance of redox state in lungs induced by hypoxia has been suggested as a participant in the changes observed in lung function in the hypoxic context, such as hypoxic vasoconstriction and pulmonary edema, in addition to vascular remodeling and chronic pulmonary hypertension. In this work, experimental evidence that shows the implied mechanisms in pulmonary redox state by hypoxia is reviewed. Herein, studies of cultures of different lung cells and complete isolated lung and tests conducted in vivo in the different forms of hypoxia, conducted in both animal models and humans, are described. PMID:22966417

  1. Hypoxia-Independent Downregulation of Hypoxia-Inducible Factor 1 Targets by Androgen Deprivation Therapy in Prostate Cancer

    SciTech Connect

    Ragnum, Harald Bull; Røe, Kathrine; Holm, Ruth; Vlatkovic, Ljiljana; Nesland, Jahn Marthin; Aarnes, Eva-Katrine; Ree, Anne Hansen; Flatmark, Kjersti; Seierstad, Therese; Lilleby, Wolfgang; Lyng, Heidi

    2013-11-15

    Purpose: We explored changes in hypoxia-inducible factor 1 (HIF1) signaling during androgen deprivation therapy (ADT) of androgen-sensitive prostate cancer xenografts under conditions in which no significant change in immunostaining of the hypoxia marker pimonidazole had occurred. Methods and Materials: Gene expression profiles of volume-matched androgen-exposed and androgen-deprived CWR22 xenografts, with similar pimonidazole-positive fractions, were compared. Direct targets of androgen receptor (AR) and HIF1 transcription factors were identified among the differentially expressed genes by using published lists. Biological processes affected by ADT were determined by gene ontology analysis. HIF1α protein expression in xenografts and biopsy samples from 35 patients receiving neoadjuvant ADT was assessed by immunohistochemistry. Results: A total of 1344 genes showed more than 2-fold change in expression by ADT, including 35 downregulated and 5 upregulated HIF1 targets. Six genes were shared HIF1 and AR targets, and their downregulation was confirmed with quantitative RT-PCR. Significant suppression of the biological processes proliferation, metabolism, and stress response in androgen-deprived xenografts was found, consistent with tumor regression. Nineteen downregulated HIF1 targets were involved in those significant biological processes, most of them in metabolism. Four of these were shared AR and HIF1 targets, including genes encoding the regulatory glycolytic proteins HK2, PFKFB3, and SLC2A1. Most of the downregulated HIF1 targets were induced by hypoxia in androgen-responsive prostate cancer cell lines, confirming their role as hypoxia-responsive HIF1 targets in prostate cancer. Downregulation of HIF1 targets was consistent with the absence of HIF1α protein in xenografts and downregulation in patients by ADT (P<.001). Conclusions: AR repression by ADT may lead to downregulation of HIF1 signaling independently of hypoxic fraction, and this may contribute to

  2. Historical Assessment of Hypoxia in Narragansett Bay Using Geochemical Markers

    EPA Science Inventory

    Eutrophication due to anthropogenic activities has affected aquatic ecosystems globally. Increased inputs of nitrogen and other nutrients to estuarine and marine ecosystems as a result of agricultural practices, urbanization and suburbanization have resulted in degradation of wat...

  3. Chronic hypoxia in pregnancy affects thymus development in Balb/c mouse offspring via IL2 Signaling.

    PubMed

    Zhang, Xiaopeng; Zhou, Xiuwen; Li, Lingjun; Sun, Miao; Gao, Qingqing; Zhang, Pengjie; Tang, Jiaqi; He, Yu; Zhu, Di; Xu, Zhice

    2016-04-01

    Hypoxia during pregnancy can adversely affect development. This study, addressed the impact of prenatal hypoxia on thymus development in the rodent offspring. Pregnant Balb/c mice were exposed to hypoxia or normoxia during pregnancy, and the thymuses of their offspring were tested. Chronic hypoxia during pregnancy resulted in significantly decreased fetal body weight, with an increased thymus-to-body weight ratio. Histological analysis revealed a smaller cortical zone in the thymus of the offspring exposed to hypoxia. A reduction in the cortical T lymphocyte population corresponded to increased mRNA abundance of caspase 3 (Casp3) and decreased expression of the proliferation marker Ki-67 (Mki67). Differences in T lymphocyte sub-populations in the thymus further indicate that thymus development in offspring was retarded or stagnated by prenatal hypoxia. The abundance of IL2 and its receptor was reduced in the thymus following prenatal hypoxia. This was accompanied by an increase in thymus HIF1A and IKKβ and a decrease in phosphorylated NFKB, MAP2K1, and MAPK1/3 compared to control pregnancies. Together, these results implicate deficiencies in IL2-mediated signaling as one source of prenatal-hypoxia-impaired thymus development. PMID:26918321

  4. Exposure to hypobaric hypoxia results in higher oxidative stress compared to normobaric hypoxia.

    PubMed

    Ribon, A; Pialoux, V; Saugy, J J; Rupp, T; Faiss, R; Debevec, T; Millet, G P

    2016-03-01

    Sixteen healthy exercise trained participants underwent the following three, 10-h exposures in a randomized manner: (1) Hypobaric hypoxia (HH; 3450m terrestrial altitude) (2) Normobaric hypoxia (NH; 3450m simulated altitude) and (3) Normobaric normoxia (NN). Plasma oxidative stress (malondialdehyde, MDA; advanced oxidation protein products, AOPP) and antioxidant markers (superoxide dismutase, SOD; glutathione peroxidase, GPX; catalase; ferric reducing antioxidant power, FRAP) were measured before and after each exposure. MDA was significantly higher after HH compared to NN condition (+24%). SOD and GPX activities were increased (vs. before; +29% and +54%) while FRAP was decreased (vs. before; -34%) only after 10h of HH. AOPP significantly increased after 10h for NH (vs. before; +83%), and HH (vs. before; +99%) whereas it remained stable in NN. These results provide evidence that prooxidant/antioxidant balance was impaired to a greater degree following acute exposure to terrestrial (HH) vs. simulated altitude (NH) and that the chamber confinement (NN) did likely not explain these differences. PMID:26732282

  5. Intrinsic time quantum geometrodynamics

    NASA Astrophysics Data System (ADS)

    Ita, Eyo Eyo; Soo, Chopin; Yu, Hoi-Lai

    2015-08-01

    Quantum geometrodynamics with intrinsic time development and momentric variables is presented. An underlying SU(3) group structure at each spatial point regulates the theory. The intrinsic time behavior of the theory is analyzed, together with its ground state and primordial quantum fluctuations. Cotton-York potential dominates at early times when the universe was small; the ground state naturally resolves Penrose's Weyl curvature hypothesis, and thermodynamic and gravitational "arrows of time" point in the same direction. Ricci scalar potential corresponding to Einstein's general relativity emerges as a zero-point energy contribution. A new set of fundamental commutation relations without Planck's constant emerges from the unification of gravitation and quantum mechanics.

  6. Influence of moderate hypoxia on vaccine efficacy against Vibrio anguillarum in Oreochromis niloticus (Nile tilapia).

    PubMed

    Gallage, Sanchala; Katagiri, Takayuki; Endo, Makoto; Futami, Kunihiko; Endo, Masato; Maita, Masashi

    2016-04-01

    Hypoxia is known as a potential immunomodulator in fish. This study therefore assesses the impact of chronic, moderate hypoxia on vaccine efficacy in Oreochromis niloticus. Serum antibody titer was used as a surrogate marker to detect vaccine efficacy. The fish were acclimatized to either moderate hypoxia (55 ± 5% DO) or normoxia (85 ± 5%DO) and immunized with formalin inactivated Vibrio anguillarum. Significantly, a higher antibody titer was found in normoxic fish than in moderate hypoxia. The normoxic group titer peaked at 14th dpv (days post vaccination) while the moderate hypoxic group peaked at 21st or 28th dpv. The absolute blood lymphocyte counts and serum bactericidal activities against V. anguillarum were significantly higher in normoxic fish. Serum killing of V. anguillarum appeared to be mainly via antibody-dependent classical complement pathway. Furthermore, the first week following vaccination appears critical for antibody production. This view was further supported by results obtained from gene expression assay, where the transcription level of all the detected immune related genes (IgM, IL-1 β, TCR-β, MHC-II β), except B cell activating factor, were significantly suppressed following exposure to moderate hypoxia. The overall results highlight that even though moderate hypoxia is not easily detectable in Oreochromis niloticus, it negatively affects antibody production by suppressing and delaying antibody response, ultimately affecting vaccine efficacy. PMID:26915308

  7. Original Research: Diametric effects of hypoxia on pathophysiology of sickle cell disease in a murine model.

    PubMed

    Tan, Fang; Ghosh, Samit; Mosunjac, Mario; Manci, Elizabeth; Ofori-Acquah, Solomon Fiifi

    2016-04-01

    Hypoxia causes erythrocyte sickling in vitro; however, its role in the pathophysiology of sickle cell disease is poorly understood. We report that hypoxia rapidly decreased oxygen saturation in transgenic sickle cell disease mice, but this effect was immediately buffered by a robust ventilatory response. The initial hypoxemia improved steadily throughout the duration of hypoxia without any detectable acute pulmonary adverse effect. Furthermore, the mice suffered acute anemia that ironically was associated with lowering of both plasma hemoglobin and heme. These results were corroborated by increased plasma haptoglobin and hemopexin levels. Markers of ischemic tissue injury increased spatiotemporally following repeated hypoxia exposures. This variation was supported by organ-specific induction of hypoxia-responsive genes. Our results show that hypoxia exerts diametric effects on sickle cell disease by promoting ischemic injury while enhancing the expression of hemolysis scavenger molecules. This phenomenon may help to understand the disparate clinical syndromes associated with hemolysis and vaso-occlusion in sickle cell disease. PMID:27026725

  8. EMAP-II-dependent lymphocyte killing is associated with hypoxia in colorectal cancer

    PubMed Central

    Youssef, M M S; Symonds, P; Ellis, I O; Murray, J C

    2006-01-01

    Endothelial-monocyte-activating polypeptide-II (EMAP-II) is a novel multifunctional polypeptide with proinflammatory activity. We have previously shown that the recombinant and native forms of EMAP-II can induce apoptosis in mitogen-stimulated lymphocytes, and that the release of this protein into the extracellular milieu is enhanced by hypoxia. We hypothesised that hypoxia may lead to death of tumour-infiltrating lymphocytes (TILs) via an EMAP-II-dependent mechanism, thereby assisting tumours to evade the immune system. In this study, we used immunohistochemistry to detect EMAP-II, active caspase-3 and cleaved Poly (ADP-ribose) Polymerase (PARP) as indicators of apoptosis in TILs, and carbonic anhydrase IX (CA IX) as a surrogate marker of hypoxia. EMAP-II expression is associated with regions of hypoxia, and furthermore there is a significant association between TILs apoptosis and the presence of hypoxia. Using a coculture model of colorectal cancer cell/lymphocyte interactions, we were also able to demonstrate lymphocyte apoptosis induced by tumour cells, with concomitant caspase-3 activity. Lymphocyte killing was enhanced by direct cell–cell contact, particularly by tumour cells exposed to hypoxic conditions. Our data support the hypothesis that hypoxia plays a role in immune evasion by tumour cells, through EMAP-II-dependent lymphocyte killing. PMID:16929248

  9. mRNA expression levels of hypoxia-induced and stem cell-associated genes in human glioblastoma.

    PubMed

    Bache, Matthias; Rot, Swetlana; Keßler, Jacqueline; Güttler, Antje; Wichmann, Henri; Greither, Thomas; Wach, Sven; Taubert, Helge; Söling, Ariane; Bilkenroth, Udo; Kappler, Matthias; Vordermark, Dirk

    2015-06-01

    The roles of hypoxia-induced and stem cell-associated genes in the development of malignancy and tumour progression are well known. However, there are a limited number of studies analysing the impact of mRNA expression levels of hypoxia-induced and stem cell-associated genes in the tissues of brain tumours and glioblastoma patients. In this study, tumour tissues from patients with glioblastoma multiforme and tumour adjacent tissues were analysed. We investigated mRNA expression levels of hypoxia-inducible factor-1α (HIF-1α), hypoxia-inducible factor-2α (HIF-2α), carbonic anhydrase 9 (CA9), vascular endothelial growth factor (VEGF), glucose transporter-1 (GLUT-1) and osteopontin (OPN), and stem cell-associated genes survivin, epidermal growth factor receptor (EGFR), human telomerase reverse transcriptase (hTERT), Nanog and octamer binding transcription factor 4 (OCT4) using quantitative real-time polymerase chain reaction (qRT-PCR). Our data revealed higher mRNA expression levels of hypoxia-induced and stem cell-associated genes in tumour tissue than levels in the tumour adjacent tissues in patients with glioblastoma multiforme. A strong positive correlation between the mRNA expression levels of HIF-2α, CA9, VEGF, GLUT-1 and OPN suggests a specific hypoxia-associated profile of mRNA expression in glioblastoma multiforme. Additionally, the results indicate the role of stem-cell-related genes in tumour hypoxia. Kaplan-Maier analysis revealed that high mRNA expression levels of hypoxia-induced markers showed a trend towards shorter overall survival in glioblastoma patients (P=0.061). Our data suggest that mRNA expression levels of hypoxia-induced genes are important tumour markers in patients with glioblastoma multiforme. PMID:25963717

  10. Hypoxia-mediated cancer stem cells in pseudopalisades with activation of hypoxia-inducible factor-1α/Akt axis in glioblastoma.

    PubMed

    Inukai, Madoka; Hara, Atsuko; Yasui, Yoshie; Kumabe, Toshihiro; Matsumoto, Toshihide; Saegusa, Makoto

    2015-10-01

    Pseudopalisades (Ps) around necrotic foci are severely hypoxic and overexpress hypoxia-inducible factor (HIF) in glioblastoma (GBM). Hypoxic regions have been proposed as one of several distinct niches for cancer stem cells (CSCs) in GBM, but little is known about the association between Ps features and CSC properties. Herein, we focused on the biological role of Ps lesions. In clinical cases of GBM, expression of hypoxia-related molecules including HIF-1α, Glut-1, p27(Kip1), and pAkt was significantly increased in perinecrotic Ps lesions compared with nonnecrotic areas and perinecrotic lesions lacking Ps features. Significantly higher expression levels of several CSC-related markers, including CD133, Sox2, CD44s, and aldehyde dehydrogenase (ALDH) 1, were also observed in Ps lesions, which were positively correlated with expression of hypoxia-related molecules and pAkt. Ps lesions also showed increased number of apoptotic cells and decreased bcl-2 and survivin expression compared with the surrounding tissue. Short-term exposure of astrocytoma cell lines to cobalt chloride, which is known to mimic the effect of hypoxia, caused an increase in expression of both hypoxia- and CSC-related markers, in line with increases in the ALDH(high) cell population and number of spheroids. Inhibition of endogenous Akt by LY294002 resulted in decreased expression of Sox2, ALDH1, and CD133, leading to enhancement of cobalt chloride-mediated apoptotic events due to altered ratio of bcl-2 to bax expression. These findings suggest that Ps lesions within GBM may serve as a specialized hypoxic niche, in which the HIF-1α/pAkt axis is activated, in response to severe hypoxia. PMID:26256949

  11. Predicting Intrinsic Motivation

    ERIC Educational Resources Information Center

    Martens, Rob; Kirschner, Paul A.

    2004-01-01

    Intrinsic motivation can be predicted from participants' perceptions of the social environment and the task environment (Ryan & Deci, 2000)in terms of control, relatedness and competence. To determine the degree of independence of these factors 251 students in higher vocational education (physiotherapy and hotel management) indicated the extent to…

  12. Hypoxia enhances differentiation of mouse embryonic stem cells into definitive endoderm and distal lung cells.

    PubMed

    Pimton, Pimchanok; Lecht, Shimon; Stabler, Collin T; Johannes, Gregg; Schulman, Edward S; Lelkes, Peter I

    2015-03-01

    We investigated the effects of hypoxia on spontaneous (SP)- and activin A (AA)-induced definitive endoderm (DE) differentiation of mouse embryonic stem cells (mESCs) and their subsequent differentiation into distal pulmonary epithelial cells. SP differentiation for 6 days of mESCs toward endoderm at hypoxia of 1% O2, but not at 3% or 21% (normoxia), increased the expression of Sox17 and Foxa2 by 31- and 63-fold above maintenance culture, respectively. Treatment of mESCs with 20 ng/mL AA for 6 days under hypoxia further increased the expression of DE marker genes Sox17, Foxa2, and Cxcr4 by 501-, 1,483-, and 126-fold above maintenance cultures, respectively. Transient exposure to hypoxia, as short as 24 h, was sufficient to enhance AA-induced endoderm formation. The involvement of hypoxia-inducible factor (HIF)-1α and reactive oxygen species (ROS) in the AA-induced endoderm enrichment was assessed using HIF-1α(-/-) mESCs and the ROS scavenger N-acetylcysteine (NAC). Under SP conditions, HIF-1α(-/-) mESCs failed to increase the expression of endodermal marker genes but rather shifted toward ectoderm. Hypoxia induced only a marginal potentiation of AA-induced endoderm differentiation in HIF-1α(-/-) mESCs. Treatment of mESCs with AA and NAC led to a dose-dependent decrease in Sox17 and Foxa2 expression. In addition, the duration of exposure to hypoxia in the course of a recently reported lung differentiation protocol resulted in differentially enhanced expression of distal lung epithelial cell marker genes aquaporin 5 (Aqp5), surfactant protein C (Sftpc), and secretoglobin 1a1 (Scgb1a1) for alveolar epithelium type I, type II, and club cells, respectively. Our study is the first to show the effects of in vitro hypoxia on efficient formation of DE and lung lineages. We suggest that the extent of hypoxia and careful timing may be important components of in vitro differentiation bioprocesses for the differential generation of distal lung epithelial cells from

  13. Hypoxia regulates SOX2 expression to promote prostate cancer cell invasion and sphere formation

    PubMed Central

    Bae, Kyung-Mi; Dai, Yao; Vieweg, Johannes; Siemann, Dietmar W

    2016-01-01

    SOX2 is an embryonic stem cell marker that in prostate cancer has been associated not only with tumorigenesis but also metastasis. Furthermore hypoxia in primary tumors has been linked to poor prognosis and outcomes in this disease. The goal of the present study was to investigate the impact of hypoxia on SOX2 expression and metastasis-associated functions in prostate cancer cells. A tissue microarray of 80 samples from prostate cancer patients or healthy controls was employed to examine the expression of HIF-1α and its correlation with SOX2. The role of SOX2 and HIF-1/2α in the regulation of cell invasion and sphere formation capacity under hypoxic conditions was investigated in vitro using short hairpin RNA (shRNA)-mediated knockdown in three human prostate cancer cell lines. HIF-1α expression was significantly elevated in malignant prostate tissue compared to benign or normal tissue, and in tumor samples its expression was highly correlated with SOX2. In prostate cancer cells, acute and chronic exposures to hypoxia that resulted in elevated expression levels of HIF-1α and HIF-2α, respectively, also induced SOX2. Genetic depletion of SOX2 attenuated hypoxia-induced cell functions. Knockdown of HIF-1α, but not HIF-2α, decreased acute hypoxia-mediated cell invasion and SOX2 up-regulation, whereas only HIF-2α gene silencing reduced sphere formation capacity and chronic hypoxia-mediated SOX2 up-regulation. Enhanced SOX2 expression and HIF-1α or HIF-2α associated phenotypes are dependent on the time duration of exposure to hypoxia. The present results indicate that SOX2 may be a key mediator of hypoxia-induced metastasis-associated functions and hence may serve as a potential target for therapeutic interventions for metastatic prostate cancer. PMID:27294000

  14. Guanfacine ameliorates hypobaric hypoxia induced spatial working memory deficits.

    PubMed

    Kauser, H; Sahu, S; Kumar, S; Panjwani, U

    2014-01-17

    Hypobaric hypoxia (HH) observed at high altitude causes mild cognitive impairment specifically affecting attention and working memory. Adrenergic dysregulation and neuronal damage in prefrontal cortex (PFC) has been implicated in hypoxia induced memory deficits. Optimal stimulation of alpha 2A adrenergic receptor in PFC facilitates the spatial working memory (SWM) under the conditions of adrenergic dysregulation. Therefore the present study was designed to test the efficacy of alpha 2A adrenergic agonist, Guanfacine (GFC), to restore HH induced SWM deficits and PFC neuronal damage. The rats were exposed to chronic HH equivalent to 25,000ft for 7days in an animal decompression chamber and received daily treatment of GFC at a dose of 1mg/kg body weight via the intramuscular route during the period of exposure. The cognitive performance was assessed by Delayed Alternation Task (DAT) using T-Maze and PFC neuronal damage was studied by apoptotic and neurodegenerative markers. Percentage of correct choice decreased significantly while perseverative errors showed a significant increase after 7days HH exposure, GFC significantly ameliorated the SWM deficits and perseveration. There was a marked and significant increase in chromatin condensation, DNA fragmentation, neuronal pyknosis and fluoro Jade positive cells in layer II of the medial PFC in hypoxia exposed group, administration of GFC significantly reduced the magnitude of these changes. Modulation of adrenergic mechanisms by GFC may serve as an effective countermeasure in amelioration of prefrontal deficits and neurodegenerative changes during HH. PMID:24184415

  15. Wound Hypoxia in Deep Tissue after Incision in the Rats

    PubMed Central

    Kang, Sinyoung; Lee, Dongchul; Theusch, Brett E.; Arpey, Christopher J.; Brennan, Timothy J.

    2013-01-01

    Our previous studies using rat models of incisional pain have demonstrated that tissue lactate levels increase and pH decreases for several days after incision, suggesting the presence of an ischemic-like condition. The purpose of this study was to evaluate the time course and the extent of tissue hypoxia that develops in incised muscle and skin. We directly measured oxygen tension at several time points after incisions of the gastrocnemius muscle, the paraspinal skin, and the plantar hindpaw in anesthetized rats using an oxygen-sensitive microelectrode. In vivo hypoxia of the incised tissues was also evaluated immunohistochemically using a hypoxia marker pimonidazole hydrochloride. To minimized inter-subject variability, unincised contralateral tissues were used as a control. Tissue oxygen tension was decreased in both skeletal muscle and skin compared to control, for several days after incision: when measured directly, oxygen tension decreased immediately and remained low for several days after incisions. Pimonidazole immunostaining revealed hypoxic areas in incised muscle and skin for several days. By postoperative day 10, tissue oxygen tension recovered to that of control tissue. These results support the evidence that a hypoxic condition is present in deep tissue after incisions and that an ischemic-like mechanism may contribute to postoperative pain. PMID:23926943

  16. Monitoring Tumor Hypoxia Using 18F-FMISO PET and Pharmacokinetics Modeling after Photodynamic Therapy

    PubMed Central

    Tong, Xiao; Srivatsan, Avinash; Jacobson, Orit; Wang, Yu; Wang, Zhantong; Yang, Xiangyu; Niu, Gang; Kiesewetter, Dale O.; Zheng, Hairong; Chen, Xiaoyuan

    2016-01-01

    Photodynamic therapy (PDT) is an efficacious treatment for some types of cancers. However, PDT-induced tumor hypoxia as a result of oxygen consumption and vascular damage can reduce the efficacy of this therapy. Measuring and monitoring intrinsic and PDT-induced tumor hypoxia in vivo during PDT is of high interest for prognostic and treatment evaluation. In the present study, static and dynamic 18F-FMISO PET were performed with mice bearing either U87MG or MDA-MB-435 tumor xenografts immediately before and after PDT at different time points. Significant difference in tumor hypoxia in response to PDT over time was found between the U87MG and MDA-MB-435 tumors in both static and dynamic PET. Dynamic PET with pharmacokinetics modeling further monitored the kinetics of 18F-FMISO retention to hypoxic sites after treatment. The Ki and k3 parametric analysis provided information on tumor hypoxia by distinction of the specific tracer retention in hypoxic sites from its non-specific distribution in tumor. Dynamic 18F-FMISO PET with pharmacokinetics modeling, complementary to static PET analysis, provides a potential imaging tool for more detailed and more accurate quantification of tumor hypoxia during PDT. PMID:27546160

  17. PET radiopharmaceuticals for imaging of tumor hypoxia: a review of the evidence

    PubMed Central

    Lopci, Egesta; Grassi, Ilaria; Chiti, Arturo; Nanni, Cristina; Cicoria, Gianfranco; Toschi, Luca; Fonti, Cristina; Lodi, Filippo; Mattioli, Sandro; Fanti, Stefano

    2014-01-01

    Hypoxia is a pathological condition arising in living tissues when oxygen supply does not adequately cover the cellular metabolic demand. Detection of this phenomenon in tumors is of the utmost clinical relevance because tumor aggressiveness, metastatic spread, failure to achieve tumor control, increased rate of recurrence, and ultimate poor outcome are all associated with hypoxia. Consequently, in recent decades there has been increasing interest in developing methods for measurement of oxygen levels in tumors. Among the image-based modalities for hypoxia assessment, positron emission tomography (PET) is one of the most extensively investigated based on the various advantages it offers, i.e., broad range of radiopharmaceuticals, good intrinsic resolution, three-dimensional tumor representation, possibility of semiquantification/quantification of the amount of hypoxic tumor burden, overall patient friendliness, and ease of repetition. Compared with the other non-invasive techniques, the biggest advantage of PET imaging is that it offers the highest specificity for detection of hypoxic tissue. Starting with the 2-nitroimidazole family of compounds in the early 1980s, a great number of PET tracers have been developed for the identification of hypoxia in living tissue and solid tumors. This paper provides an overview of the principal PET tracers applied in cancer imaging of hypoxia and discusses in detail their advantages and pitfalls. PMID:24982822

  18. The earliest neuronal responses to hypoxia in the neocortical circuit are glutamate-dependent.

    PubMed

    Revah, Omer; Lasser-Katz, Efrat; Fleidervish, Ilya A; Gutnick, Michael J

    2016-11-01

    Soon after exposure to hypoxia or ischemia, neurons in cortical tissues undergo massive anoxic depolarization (AD). This precipitous event is preceded by more subtle neuronal changes, including enhanced excitatory and inhibitory synaptic transmitter release. Here, we have used patch-in-slice techniques to identify the earliest effects of acute hypoxia on the synaptic and intrinsic properties of Layer 5 neurons, to determine their time course and to evaluate the role of glutamate receptors in their generation. Coronal slices of mouse somatosensory cortex were maintained at 36°C in an interface chamber and challenged with episodes of hypoxia. In recordings with cell-attached electrodes, the open probability of Ca(2+)-dependent BK channels began to increase within seconds of hypoxia onset, indicating a sharp rise in [Ca(2+)]i just beneath the membrane. By using a high concentration of K(+) in the pipette, we simultaneously monitored the membrane potential and showed that the [Ca(2+)]i rise was not associated with membrane depolarization. The earliest hypoxia-induced synaptic disturbance was a marked increase in the frequency of sPSCs, which also began soon after the removal of oxygen and long before AD. This synaptic effect was accompanied by depletion of the readily releasable transmitter pools, as demonstrated by a decreased response to hyperosmotic solutions. The early [Ca(2+)]i rise, the early increase in transmitter release and the subsequent AD itself were all prevented by bathing in a cocktail containing blockers of ionotropic glutamate receptors. We found no evidence for involvement of pannexin hemichannels or TRPM7 channels in the early responses to hypoxia in this experimental preparation. Our data indicate that the earliest cellular consequences of cortical hypoxia are triggered by activation of glutamate-gated channels. PMID:27443966

  19. Development of Hypoxia in a Preclinical Model of Tumor Micrometastases

    SciTech Connect

    Simonsen, Trude G.; Gaustad, Jon-Vidar; Rofstad, Einar K.

    2010-03-01

    Purpose: Hypoxic regions have been shown to be a characteristic feature of a wide variety of human primary tumors, whereas the oxygenation status of subclinical micrometastases is in general unknown. The development of hypoxia in a xenograft model of microscopic metastases was investigated in this study. Methods and Materials: U-25-GFP human melanomas growing in dorsal window chamber preparations in BALB/c nu/nu mice were used as a preclinical model of micrometastases. Tumor blood supply time and morphologic parameters of the vascular network were determined from first-pass imaging movies and vascular maps recorded by use of 155-kDa tetramethylrhodamine isothiocyanate-labeled dextran as a vascular tracer. Tumor hypoxia was assessed from immunohistochemical preparations of the imaged tissue by use of pimonidazole as a hypoxia marker. Results: Nearly half of the tumors had developed hypoxic regions when they reached a diameter of 2 to 3 mm. Tumors with multiple hypoxic foci showed a low growth rate, low blood flow velocity, high vessel tortuosity, high vessel segment length, and high vascular density, whereas tumors with a single hypoxic region showed a high growth rate, high blood flow velocity, low vessel tortuosity, low vessel segment length, and low vascular density. The tumors with hypoxic regions did not differ from those without hypoxia in any single parameter. Conclusions: U-25-GFP xenograft models of vascularized human tumor micrometastases may develop hypoxic regions as a consequence of two distinctly different morphologic abnormalities in the vascular network: high resistance against blood flow (i.e., high vessel tortuosity and high vessel segment length) or low vascular density.

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

    PubMed Central

    Maeda, Koki; Ding, Qiang; Yoshimitsu, Makoto; Kuwahata, Taisaku; Miyazaki, Yumi; Tsukasa, Koichirou; Hayashi, Tomomi; Shinchi, Hiroyuki; Natsugoe, Shoji; Takao, Sonshin

    2016-01-01

    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. PMID:27367674

  1. Estradiol, TGF-β1 and hypoxia promote breast cancer stemness and EMT-mediated breast cancer migration

    PubMed Central

    PARK, SEONG-JOON; KIM, JOONG-GOOK; KIM, NAM DEUK; YANG, KWANGMO; SHIM, JAE WOONG; HEO, KYU

    2016-01-01

    Breast cancer is one of the most common cancer types among women, acting as a distinct cause of mortality, and has a high incidence of recurrence. External stimuli, including 17β-estradiol (E2), transforming growth factor (TGF)-β1 and hypoxia, may be important in breast cancer growth and metastasis. However, the effects of these stimuli on breast cancer stem cell (CSC) regulation have not been fully investigated. In the present study, the proportion of cluster of differentiation (CD)44+/CD24−/low cells increased following treatment with E2, TGF-β1 and hypoxia in MCF-7 cells. The expression of CSC markers, including SOX2, KLF4 and ABCG2, was upregulated continually by E2, TGF-β1 and hypoxia. In addition, the expression levels of epithelial-mesenchymal transition-associated factors increased following treatment with E2, TGF-β1 and hypoxia. Therefore, the migration ability of E2-, TGF-β1- and hypoxia-treated MCF-7 cells was enhanced compared with control cells. In addition, the enhancement of apoptosis by 5-flurouracil or radiation was abolished following treatment with E2, TGF-β1 and hypoxia. These results indicate that E2, TGF-β1 and hypoxia are important for regulating breast CSCs, and that the modulation of the microenvironment in tumors may improve the efficiency of breast cancer therapy. PMID:26998096

  2. Intrinsic and extrinsic mortality reunited.

    PubMed

    Koopman, Jacob J E; Wensink, Maarten J; Rozing, Maarten P; van Bodegom, David; Westendorp, Rudi G J

    2015-07-01

    Intrinsic and extrinsic mortality are often separated in order to understand and measure aging. Intrinsic mortality is assumed to be a result of aging and to increase over age, whereas extrinsic mortality is assumed to be a result of environmental hazards and be constant over age. However, allegedly intrinsic and extrinsic mortality have an exponentially increasing age pattern in common. Theories of aging assert that a combination of intrinsic and extrinsic stressors underlies the increasing risk of death. Epidemiological and biological data support that the control of intrinsic as well as extrinsic stressors can alleviate the aging process. We argue that aging and death can be better explained by the interaction of intrinsic and extrinsic stressors than by classifying mortality itself as being either intrinsic or extrinsic. Recognition of the tight interaction between intrinsic and extrinsic stressors in the causation of aging leads to the recognition that aging is not inevitable, but malleable through the environment. PMID:25916736

  3. Systemic oxygenation weakens the hypoxia and Hypoxia Inducible Factor 1α-dependent and extracellular adenosine-mediated tumor protection

    PubMed Central

    Hatfield, Stephen M.; Kjaergaard, Jorgen; Lukashev, Dmitriy; Belikoff, Bryan; Schreiber, Taylor H.; Sethumadhavan, Shalini; Abbott, Robert; Philbrook, Phaethon; Thayer, Molly; Shujia, Dai; Rodig, Scott; Kutok, Jeffrey L.; Ren, Jin; Ohta, Akio; Podack, Eckhard R.; Karger, Barry; Jackson, Edwin K.; Sitkovsky, Michail

    2014-01-01

    Intratumoral hypoxia and Hypoxia Inducible Factor-1α (HIF-1α)-dependent CD39/CD73 ecto-enzymes may govern the accumulation of tumor-protecting extracellular adenosine and signaling through the A2A adenosine receptors (A2AR) in tumor microenvironments (TME). Here, we explored the conceptually novel motivation to use supplemental oxygen as a treatment to inhibit the hypoxia/HIF-1α-CD39/CD73-driven accumulation of extracellular adenosine in the TME in order to weaken the tumor protection. We report that hyperoxic breathing (60% O2) decreased the TME hypoxia, as well as levels of HIF-1α and downstream target proteins of HIF-1α in the TME according to proteomics studies in mice. Importantly, oxygenation also down-regulated the expression of adenosine-generating ecto-enzymes and significantly lowered levels of tumor-protecting extracellular adenosine in the TME. Using supplemental oxygen as a tool in studies of the TME, we also identified FHL-1 as a potentially useful marker for the conversion of hypoxic into normoxic TME. Hyperoxic breathing resulted in the up-regulation of antigen-presenting MHC-class I molecules on tumor cells and in the better recognition and increased susceptibility to killing by tumor-reactive cytotoxic T cells. Therapeutic breathing of 60% oxygen resulted in the significant inhibition of growth of established B16.F10 melanoma tumors and prolonged survival of mice. Taken together, the data presented here provide proof-of principle for the therapeutic potential of systemic oxygenation to convert the hypoxic, adenosine-rich and tumor-protecting TME into a normoxic and extracellular adenosine-poor TME that, in turn, may facilitate tumor regression. We propose to explore the combination of supplemental oxygen with existing immunotherapies of cancer. PMID:25120128

  4. Role of hypoxia during nephrogenesis.

    PubMed

    Hemker, Shelby L; Sims-Lucas, Sunder; Ho, Jacqueline

    2016-10-01

    Mammals develop in a physiologically hypoxic state, and the oxygen tension of different tissues in the embryo is precisely controlled. Deviation from normal oxygenation, such as what occurs in placental insufficiency, can disrupt fetal development. Several studies demonstrate that intrauterine hypoxia has a negative effect on kidney development. As nascent nephrons are forming from nephron progenitors in the nephrogenic zone, they are exposed to varying oxygen tension by virtue of the development of the renal vasculature. Thus, nephrogenesis may be linked to oxygen tension. However, the mechanism(s) by which this occurs remains unclear. This review focuses on what is known about molecular mechanisms active in physiological and pathological hypoxia and their effects on kidney development. PMID:26872484

  5. Hypoxia-Sensitive Materials for Biomedical Applications.

    PubMed

    Yu, Jicheng; Zhang, Yuqi; Hu, Xiuli; Wright, Grace; Gu, Zhen

    2016-06-01

    Hypoxia is a typical hallmark of various diseases, including cancer, ischemic diseases, and stroke. It is also associated with the disease progression. Therefore, it is critical to develop an effective strategy to target the hypoxic region for diagnosis and treatment. In this review, we summarize recent progress in the development of hypoxia-responsive systems for imaging, sensing and therapy. Two types of hypoxia-sensitive systems, the hypoxia inducible factor-1 based systems and bioreductive molecule based systems, were reviewed with comments on their advantages and limitations. Future opportunities and challenges are also discussed in the end. PMID:26926694

  6. Size restricted silymarin suspension evokes integrated adaptive response against acute hypoxia exposure in rat lung.

    PubMed

    Paul, Subhojit; Arya, Aditya; Gangwar, Anamika; Bhargava, Kalpana; Ahmad, Yasmin

    2016-07-01

    Despite its extraordinary antioxidant capacity, the clinical usage of silymarin has remained restricted to amelioration of hepatic pathology. Perhaps its low bioavailability and uneven bio-distribution, owing to its poor aqueous solubility, are two main causes that have dampened the clinical applicability and scope of this preparation. We took these two challenges and suggested an unexplored application of silymarin. Apart from liver, two of the most susceptible vital organs at the highest risk of oxidative stress are brain and lung, especially during reduced oxygen saturation (hypoxia) at anatomical level. Hypoxia causes excess generation of radicals primarily in the lungs as it is the first organ at the interphase of atmosphere and organism making it the most prone and vulnerable to oxidative stress and the first responder against hypobaric hypoxia. As our first objective, we improved the silymarin formulation by restricting its size to the lower threshold and then successfully tested the prophylactic and therapeutic action in rat lung challenged with simulated hypobaric hypoxia. After dose optimization, we observed that 50mg/kg BW silymarin as size restricted and homogenous aqueous suspension successfully minimized the reactive oxygen species and augmented the antioxidant defense by significant upregulation of catalase and superoxide dismutase and reduced glutathione. Moreover, the well-established hypoxia markers and proteins related to hypoxia adaptability, hif1a and VEGF were differentially regulated conferring significant reduction in the inflammation caused by hypobaric hypoxia. We therefore report,the unexplored potential benefits of silymarin for preventing high altitude associated pathophysiology further paving its road to clinical trials. PMID:27105952

  7. Differential roles of hypoxia and innate immunity in juvenile and adult dermatomyositis.

    PubMed

    Preuße, Corinna; Allenbach, Yves; Hoffmann, Olaf; Goebel, Hans-Hilmar; Pehl, Debora; Radke, Josefine; Doeser, Alexandra; Schneider, Udo; Alten, Rieke H E; Kallinich, Tilmann; Benveniste, Olivier; von Moers, Arpad; Schoser, Benedikt; Schara, Ulrike; Stenzel, Werner

    2016-01-01

    Dermatomyositis (DM) can occur in both adults and juveniles with considerable clinical differences. The links between immune-mediated mechanisms and vasculopathy with respect to development of perifascicular pathology are incompletely understood. We investigated skeletal muscle from newly diagnosed, treatment-naïve juvenile (jDM) and adult dermatomyositis (aDM) patients focusing on hypoxia-related pathomechanisms, vessel pathology, and immune mechanisms especially in the perifascicular region. Therefore, we assessed the skeletal muscle biopsies from 21 aDM, and 15 jDM patients by immunohistochemistry and electron microscopy. Transcriptional analyses of genes involved in hypoxia, as well as in innate and adaptive immunity were performed by quantitative Polymerase chain reaction (qPCR) of whole tissue cross sections including perifascicular muscle fibers.Through these analysis, we found that basic features of DM, like perifascicular atrophy and inflammatory infiltrates, were present at similar levels in jDM and aDM patients. However, jDM was characterized by predominantly hypoxia-driven pathology in perifascicular small fibers and by macrophages expressing markers of hypoxia. A more pronounced regional loss of capillaries, but no relevant activation of type-1 Interferon (IFN)-associated pathways was noted. Conversely, in aDM, IFN-related genes were expressed at significantly elevated levels, and Interferon-stimulated gene (ISG)15 was strongly positive in small perifascicular fibers whereas hypoxia-related mechanisms did not play a significant role.In our study we could provide new molecular data suggesting a conspicuous pathophysiological 'dichotomy' between jDM and aDM: In jDM, perifascicular atrophy is tightly linked to hypoxia-related pathology, and poorly to innate immunity. In aDM, perifascicular atrophy is prominently associated with molecules driving innate immunity, while hypoxia-related mechanisms seem to be less relevant. PMID:27121733

  8. Vascular wall hypoxia promotes arterial thrombus formation via augmentation of vascular thrombogenicity.

    PubMed

    Matsuura, Yunosuke; Yamashita, Atsushi; Iwakiri, Takashi; Sugita, Chihiro; Okuyama, Nozomi; Kitamura, Kazuo; Asada, Yujiro

    2015-07-01

    Atherosclerotic lesions represent a hypoxic milieu. However, the significance of this milieu in atherothrombosis has not been established. We aimed to assess the hypothesis that vascular wall hypoxia promotes arterial thrombus formation. We examined the relation between vascular wall hypoxia and arterial thrombus formation using a rabbit model in which arterial thrombosis was induced by 0.5 %-cholesterol diet and repeated balloon injury of femoral arteries. Vascular wall hypoxia was immunohistochemically detected by pimonidazole hydrochloride, a hypoxia marker. Rabbit neointima and THP-1 macrophages were cultured to analyse prothrombotic factor expression under hypoxic conditions (1 % O2). Prothrombotic factor expression and nuclear localisation of hypoxia-inducible factor (HIF)-1α and nuclear factor-kappa B (NF-κB) p65 were immunohistochemically assessed using human coronary atherectomy plaques. Hypoxic areas were localised in the macrophage-rich deep portion of rabbit neointima and positively correlated with the number of nuclei immunopositive for HIF-1α and NF-κB p65, and tissue factor (TF) expression. Immunopositive areas for glycoprotein IIb/IIIa and fibrin in thrombi were significantly correlated with hypoxic areas in arteries. TF and plasminogen activator inhibitor-1 (PAI-1) expression was increased in neointimal tissues and/or macrophages cultured under hypoxia, and both were suppressed by inhibitors of either HIF-1 or NF-κB. In human coronary plaques, the number of HIF-1α-immunopositive nuclei was positively correlated with that of NF-κB-immunopositive nuclei and TF-immunopositive and PAI-1-immunopositive area, and it was significantly higher in thrombotic plaques. Vascular wall hypoxia augments the thrombogenic potential of atherosclerotic plaque and thrombus formation on plaques via prothrombotic factor upregulation. PMID:25833755

  9. Impact of interleukin-6 on hypoxia-induced pulmonary hypertension and lung inflammation in mice

    PubMed Central

    Savale, Laurent; Tu, Ly; Rideau, Dominique; Izziki, Mohamed; Maitre, Bernard; Adnot, Serge; Eddahibi, Saadia

    2009-01-01

    Background Inflammation may contribute to the pathogenesis of various forms of pulmonary hypertension (PH). Recent studies in patients with idiopathic PH or PH associated with underlying diseases suggest a role for interleukin-6 (IL-6). Methods To determine whether endogenous IL-6 contributes to mediate hypoxic PH and lung inflammation, we studied IL-6-deficient (IL-6-/-) and wild-type (IL-6+/+) mice exposed to hypoxia for 2 weeks. Results Right ventricular systolic pressure, right ventricle hypertrophy, and the number and media thickness of muscular pulmonary vessels were decreased in IL-6-/- mice compared to wild-type controls after 2 weeks' hypoxia, although the pressure response to acute hypoxia was similar in IL-6+/+ and IL-6-/- mice. Hypoxia exposure of IL-6+/+ mice led to marked increases in IL-6 mRNA and protein levels within the first week, with positive IL-6 immunostaining in the pulmonary vessel walls. Lung IL-6 receptor and gp 130 (the IL-6 signal transducer) mRNA levels increased after 1 and 2 weeks' hypoxia. In vitro studies of cultured human pulmonary-artery smooth-muscle-cells (PA-SMCs) and microvascular endothelial cells revealed prominent synthesis of IL-6 by PA-SMCs, with further stimulation by hypoxia. IL-6 also markedly stimulated PA-SMC migration without affecting proliferation. Hypoxic IL-6-/- mice showed less inflammatory cell recruitment in the lungs, compared to hypoxic wild-type mice, as assessed by lung protein levels and immunostaining for the specific macrophage marker F4/80, with no difference in lung expression of adhesion molecules or cytokines. Conclusion These data suggest that IL-6 may be actively involved in hypoxia-induced lung inflammation and pulmonary vascular remodeling in mice. PMID:19173740

  10. Arabidopsis CML38, a Calcium Sensor That Localizes to Ribonucleoprotein Complexes under Hypoxia Stress1[OPEN

    PubMed Central

    McClintock, Carlee; Li, Tian

    2016-01-01

    During waterlogging and the associated oxygen deprivation stress, plants respond by the induction of adaptive programs, including the redirected expression of gene networks toward the synthesis of core hypoxia-response proteins. Among these core response proteins in Arabidopsis (Arabidopsis thaliana) is the calcium sensor CML38, a protein related to regulator of gene silencing calmodulin-like proteins (rgsCaMs). CML38 transcripts are up-regulated more than 300-fold in roots within 6 h of hypoxia treatment. Transfer DNA insertional mutants of CML38 show an enhanced sensitivity to hypoxia stress, with lowered survival and more severe inhibition of root and shoot growth. By using yellow fluorescent protein (YFP) translational fusions, CML38 protein was found to be localized to cytosolic granule structures similar in morphology to hypoxia-induced stress granules. Immunoprecipitation of CML38 from the roots of hypoxia-challenged transgenic plants harboring CML38pro::CML38:YFP followed by liquid chromatography-tandem mass spectrometry analysis revealed the presence of protein targets associated with messenger RNA ribonucleoprotein (mRNP) complexes including stress granules, which are known to accumulate as messenger RNA storage and triage centers during hypoxia. This finding is further supported by the colocalization of CML38 with the mRNP stress granule marker RNA Binding Protein 47 (RBP47) upon cotransfection of Nicotiana benthamiana leaves. Ruthenium Red treatment results in the loss of CML38 signal in cytosolic granules, suggesting that calcium is necessary for stress granule association. These results confirm that CML38 is a core hypoxia response calcium sensor protein and suggest that it serves as a potential calcium signaling target within stress granules and other mRNPs that accumulate during flooding stress responses. PMID:26634999

  11. Arabidopsis CML38, a Calcium Sensor That Localizes to Ribonucleoprotein Complexes under Hypoxia Stress.

    PubMed

    Lokdarshi, Ansul; Conner, W Craig; McClintock, Carlee; Li, Tian; Roberts, Daniel M

    2016-02-01

    During waterlogging and the associated oxygen deprivation stress, plants respond by the induction of adaptive programs, including the redirected expression of gene networks toward the synthesis of core hypoxia-response proteins. Among these core response proteins in Arabidopsis (Arabidopsis thaliana) is the calcium sensor CML38, a protein related to regulator of gene silencing calmodulin-like proteins (rgsCaMs). CML38 transcripts are up-regulated more than 300-fold in roots within 6 h of hypoxia treatment. Transfer DNA insertional mutants of CML38 show an enhanced sensitivity to hypoxia stress, with lowered survival and more severe inhibition of root and shoot growth. By using yellow fluorescent protein (YFP) translational fusions, CML38 protein was found to be localized to cytosolic granule structures similar in morphology to hypoxia-induced stress granules. Immunoprecipitation of CML38 from the roots of hypoxia-challenged transgenic plants harboring CML38pro::CML38:YFP followed by liquid chromatography-tandem mass spectrometry analysis revealed the presence of protein targets associated with messenger RNA ribonucleoprotein (mRNP) complexes including stress granules, which are known to accumulate as messenger RNA storage and triage centers during hypoxia. This finding is further supported by the colocalization of CML38 with the mRNP stress granule marker RNA Binding Protein 47 (RBP47) upon cotransfection of Nicotiana benthamiana leaves. Ruthenium Red treatment results in the loss of CML38 signal in cytosolic granules, suggesting that calcium is necessary for stress granule association. These results confirm that CML38 is a core hypoxia response calcium sensor protein and suggest that it serves as a potential calcium signaling target within stress granules and other mRNPs that accumulate during flooding stress responses. PMID:26634999

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

    SciTech Connect

    Saxena, Saurabh; Shukla, Dhananjay; Bansal, Anju

    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

  13. Intrinsically Disordered Energy Landscapes

    NASA Astrophysics Data System (ADS)

    Chebaro, Yassmine; Ballard, Andrew J.; Chakraborty, Debayan; Wales, David J.

    2015-05-01

    Analysis of an intrinsically disordered protein (IDP) reveals an underlying multifunnel structure for the energy landscape. We suggest that such ‘intrinsically disordered’ landscapes, with a number of very different competing low-energy structures, are likely to characterise IDPs, and provide a useful way to address their properties. In particular, IDPs are present in many cellular protein interaction networks, and several questions arise regarding how they bind to partners. Are conformations resembling the bound structure selected for binding, or does further folding occur on binding the partner in a induced-fit fashion? We focus on the p53 upregulated modulator of apoptosis (PUMA) protein, which adopts an -helical conformation when bound to its partner, and is involved in the activation of apoptosis. Recent experimental evidence shows that folding is not necessary for binding, and supports an induced-fit mechanism. Using a variety of computational approaches we deduce the molecular mechanism behind the instability of the PUMA peptide as a helix in isolation. We find significant barriers between partially folded states and the helix. Our results show that the favoured conformations are molten-globule like, stabilised by charged and hydrophobic contacts, with structures resembling the bound state relatively unpopulated in equilibrium.

  14. Intrinsically Disordered Energy Landscapes

    PubMed Central

    Chebaro, Yassmine; Ballard, Andrew J.; Chakraborty, Debayan; Wales, David J.

    2015-01-01

    Analysis of an intrinsically disordered protein (IDP) reveals an underlying multifunnel structure for the energy landscape. We suggest that such ‘intrinsically disordered’ landscapes, with a number of very different competing low-energy structures, are likely to characterise IDPs, and provide a useful way to address their properties. In particular, IDPs are present in many cellular protein interaction networks, and several questions arise regarding how they bind to partners. Are conformations resembling the bound structure selected for binding, or does further folding occur on binding the partner in a induced-fit fashion? We focus on the p53 upregulated modulator of apoptosis (PUMA) protein, which adopts an -helical conformation when bound to its partner, and is involved in the activation of apoptosis. Recent experimental evidence shows that folding is not necessary for binding, and supports an induced-fit mechanism. Using a variety of computational approaches we deduce the molecular mechanism behind the instability of the PUMA peptide as a helix in isolation. We find significant barriers between partially folded states and the helix. Our results show that the favoured conformations are molten-globule like, stabilised by charged and hydrophobic contacts, with structures resembling the bound state relatively unpopulated in equilibrium. PMID:25999294

  15. Intrinsically disordered energy landscapes.

    PubMed

    Chebaro, Yassmine; Ballard, Andrew J; Chakraborty, Debayan; Wales, David J

    2015-01-01

    Analysis of an intrinsically disordered protein (IDP) reveals an underlying multifunnel structure for the energy landscape. We suggest that such 'intrinsically disordered' landscapes, with a number of very different competing low-energy structures, are likely to characterise IDPs, and provide a useful way to address their properties. In particular, IDPs are present in many cellular protein interaction networks, and several questions arise regarding how they bind to partners. Are conformations resembling the bound structure selected for binding, or does further folding occur on binding the partner in a induced-fit fashion? We focus on the p53 upregulated modulator of apoptosis (PUMA) protein, which adopts an α-helical conformation when bound to its partner, and is involved in the activation of apoptosis. Recent experimental evidence shows that folding is not necessary for binding, and supports an induced-fit mechanism. Using a variety of computational approaches we deduce the molecular mechanism behind the instability of the PUMA peptide as a helix in isolation. We find significant barriers between partially folded states and the helix. Our results show that the favoured conformations are molten-globule like, stabilised by charged and hydrophobic contacts, with structures resembling the bound state relatively unpopulated in equilibrium. PMID:25999294

  16. Predicting intrinsic brain activity.

    PubMed

    Craddock, R Cameron; Milham, Michael P; LaConte, Stephen M

    2013-11-15

    Multivariate supervised learning methods exhibit a remarkable ability to decode externally driven sensory, behavioral, and cognitive states from functional neuroimaging data. Although they are typically applied to task-based analyses, supervised learning methods are equally applicable to intrinsic effective and functional connectivity analyses. The obtained models of connectivity incorporate the multivariate interactions between all brain regions simultaneously, which will result in a more accurate representation of the connectome than the ones available with standard bivariate methods. Additionally the models can be applied to decode or predict the time series of intrinsic brain activity of a region from an independent dataset. The obtained prediction accuracy provides a measure of the integration between a brain region and other regions in its network, as well as a method for evaluating acquisition and preprocessing pipelines for resting state fMRI data. This article describes a method for learning multivariate models of connectivity. The method is applied in the non-parametric prediction accuracy, influence, and reproducibility-resampling (NPAIRS) framework, to study the regional variation of prediction accuracy and reproducibility (Strother et al., 2002). The resulting spatial distribution of these metrics is consistent with the functional hierarchy proposed by Mesulam (1998). Additionally we illustrate the utility of the multivariate regression connectivity modeling method for optimizing experimental parameters and assessing the quality of functional neuroimaging data. PMID:23707580

  17. Hypoxia in the androgen-dependent Shionogi model for prostate cancer at three stages.

    PubMed

    Skov, Kirsten; Adomat, Hans; Bowden, Mary; Dragowska, Wieslawa; Gleave, Martin; Koch, Cameron J; Woo, Janet; Yapp, Donald T T

    2004-11-01

    The objective of this study was to investigate a possible relationship between androgen status and hypoxia in the Shionogi murine prostate tumor model, which is widely used to study the effects of androgen withdrawal on hormone resistance and radiation response. Binding of the nitroimidazole hypoxia marker EF5 was assessed using the Cy3-tagged monoclonal antibody ELK3-51. Three hours after injection of EF5 (30 mg/kg), tumors from the following three stages were excised: androgen-dependent, regressed tumors 7 days after castration, and androgen-independent. Half of each tumor was disaggregated for analysis by flow cytometry and the remainder was flash frozen. Statistically significant differences (P < 0.01) were found between androgen-dependent, regressed and androgen-dependent tumors: approximately 30, approximately 2 and approximately 50% hypoxic cells, respectively. Frozen sections from androgen-dependent tumors exhibited highly variable EF5 binding; regressed tumors showed very little or no binding; each section from androgen-dependent tumors showed high levels and uniformly distributed binding of EF5. There was no correlation between the degree of hypoxia and tumor weight (P > 0.1). The results from this preliminary study indicate that hypoxia may play an important role with respect to the timing of irradiation in prostate cancer treatments and possibly may be a useful prognostic tool. In addition, hypoxia may also be relevant to progression in this disease after androgen ablation. PMID:15624309

  18. Hypoxia-induced gene expression results from selective mRNA partitioning to the endoplasmic reticulum

    PubMed Central

    Staudacher, Jonas J.; Naarmann-de Vries, Isabel S.; Ujvari, Stefanie J.; Klinger, Bertram; Kasim, Mumtaz; Benko, Edgar; Ostareck-Lederer, Antje; Ostareck, Dirk H.; Bondke Persson, Anja; Lorenzen, Stephan; Meier, Jochen C.; Blüthgen, Nils; Persson, Pontus B.; Henrion-Caude, Alexandra; Mrowka, Ralf; Fähling, Michael

    2015-01-01

    Protein synthesis is a primary energy-consuming process in the cell. Therefore, under hypoxic conditions, rapid inhibition of global mRNA translation represents a major protective strategy to maintain energy metabolism. How some mRNAs, especially those that encode crucial survival factors, continue to be efficiently translated in hypoxia is not completely understood. By comparing specific transcript levels in ribonucleoprotein complexes, cytoplasmic polysomes and endoplasmic reticulum (ER)-bound ribosomes, we show that the synthesis of proteins encoded by hypoxia marker genes is favoured at the ER in hypoxia. Gene expression profiling revealed that transcripts particularly increased by the HIF-1 transcription factor network show hypoxia-induced enrichment at the ER. We found that mRNAs favourably translated at the ER have higher conservation scores for both the 5′- and 3′-untranslated regions (UTRs) and contain less upstream initiation codons (uAUGs), indicating the significance of these sequence elements for sustained mRNA translation under hypoxic conditions. Furthermore, we found enrichment of specific cis-elements in mRNA 5′- as well as 3′-UTRs that mediate transcript localization to the ER in hypoxia. We conclude that transcriptome partitioning between the cytoplasm and the ER permits selective mRNA translation under conditions of energy shortage. PMID:25753659

  19. Hypoxia-induced autophagy as an additional mechanism in human osteosarcoma radioresistance.

    PubMed

    Feng, Helin; Wang, Jin; Chen, Wei; Shan, Baoen; Guo, Yin; Xu, Jianfa; Wang, Ling; Guo, Peng; Zhang, Yingze

    2016-06-01

    Osteosarcoma (OS) responds poorly to radiotherapy, but the mechanism is unclear. We found OS tumor tissues expressed high level of protein HIF-1α, a common biological marker indicative of hypoxia. It is known that hypoxic cells are generally radioresistant because of reduced production of irradiation-induced DNA-damaging reactive oxygen species (ROS) in the anaerobic condition. Here we report another mechanism how hypoxia induces radioresistance. In MG-63 human osteosarcoma cells, hypoxic pretreatment increased the cellular survival in irradiation. These hypoxia-exposed cells displayed compartmental recruitment of GFP-tagged LC3 and expression of protein LC3-II, and restored the radiosensitivity upon autophagy inhibition. The following immunohistochemistry of OS tumor tissue sections revealed upregulated LC3 expression in a correlation with HIF-1α protein level, implying the possibly causative link between hypoxia and autophagy. Further studies in MG-63 cells demonstrated hypoxic pretreatment reduced cellular and mitochondrial ROS production during irradiation, while inhibition of autophagy re-elicited them. Taken together, our study suggests hypoxia can confer cells resistance to irradiation through activated autophagy to accelerate the clearance of cellular ROS products. This might exist in human osteosarcoma as an additional mechanism for radioresistance. PMID:27335774

  20. Hypoxia-Induced Vascular Endothelial Growth Factor Expression Precedes Neovascularization after Cerebral Ischemia

    PubMed Central

    Marti, Hugo J. H.; Bernaudin, Myriam; Bellail, Anita; Schoch, Heike; Euler, Monika; Petit, Edwige; Risau, Werner

    2000-01-01

    We investigated the hypothesis that hypoxia induces angiogenesis and thereby may counteract the detrimental neurological effects associated with stroke. Forty-eight to seventy-two hours after permanent middle cerebral artery occlusion we found a strong increase in the number of newly formed vessels at the border of the infarction. Using the hypoxia marker nitroimidazole EF5, we detected hypoxic cells in the ischemic border of the neocortex. Expression of vascular endothelial growth factor (VEGF), which is the main regulator of angiogenesis and is inducible by hypoxia, was strongly up-regulated in the ischemic border, at times between 6 and 24 hours after occlusion. In addition, both VEGF receptors (VEGFRs) were up-regulated at the border after 48 hours and later in the ischemic core. Finally, the two transcription factors, hypoxia-inducible factor-1 (HIF-1) and HIF-2, known to be involved in the regulation of VEGF and VEGFR gene expression, were increased in the ischemic border after 72 hours, suggesting a regulatory function for these factors. These results strongly suggest that the VEGF/VEGFR system, induced by hypoxia, leads to the growth of new vessels after cerebral ischemia. Exogenous support of this natural protective mechanism might lead to enhanced survival after stroke. PMID:10702412

  1. Hypoxia Induces Epithelial-Mesenchymal Transition in Follicular Thyroid Cancer: Involvement of Regulation of Twist by Hypoxia Inducible Factor-1α

    PubMed Central

    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

    2015-01-01

    Purpose 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. Materials and Methods 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. Results 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. Conclusion 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. PMID:26446630

  2. Approximate Simulation of Acute Hypobaric Hypoxia with Normobaric Hypoxia

    NASA Technical Reports Server (NTRS)

    Conkin, J.; Wessel, J. H., III

    2011-01-01

    INTRODUCTION. Some manufacturers of reduced oxygen (O2) breathing devices claim a comparable hypobaric hypoxia (HH) training experience by providing F(sub I) O2 < 0.209 at or near sea level pressure to match the ambient O2 partial pressure (iso-pO2) of the target altitude. METHODS. Literature from investigators and manufacturers indicate that these devices may not properly account for the 47 mmHg of water vapor partial pressure that reduces the inspired partial pressure of O2 (P(sub I) O2). Nor do they account for the complex reality of alveolar gas composition as defined by the Alveolar Gas Equation. In essence, by providing iso-pO2 conditions for normobaric hypoxia (NH) as for HH exposures the devices ignore P(sub A)O2 and P(sub A)CO2 as more direct agents to induce signs and symptoms of hypoxia during acute training exposures. RESULTS. There is not a sufficient integrated physiological understanding of the determinants of P(sub A)O2 and P(sub A)CO2 under acute NH and HH given the same hypoxic pO2 to claim a device that provides isohypoxia. Isohypoxia is defined as the same distribution of hypoxia signs and symptoms under any circumstances of equivalent hypoxic dose, and hypoxic pO2 is an incomplete hypoxic dose. Some devices that claim an equivalent HH experience under NH conditions significantly overestimate the HH condition, especially when simulating altitudes above 10,000 feet (3,048 m). CONCLUSIONS. At best, the claim should be that the devices provide an approximate HH experience since they only duplicate the ambient pO2 at sea level as at altitude (iso-pO2 machines). An approach to reduce the overestimation is to at least provide machines that create the same P(sub I)O2 (iso-P(sub I)O2 machines) conditions at sea level as at the target altitude, a simple software upgrade.

  3. Intrinsic Feature Motion Tracking

    Energy Science and Technology Software Center (ESTSC)

    2013-03-19

    Subject motion during 3D medical scanning can cause blurring and artifacts in the 3D images resulting in either rescans or poor diagnosis. Anesthesia or physical restraints may be used to eliminate motion but are undesirable and can affect results. This software measures the six degree of freedom 3D motion of the subject during the scan under a rigidity assumption using only the intrinsic features present on the subject area being monitored. This movement over timemore » can then be used to correct the scan data removing the blur and artifacts. The software acquires images from external cameras or images stored on disk for processing. The images are from two or three calibrated cameras in a stereo arrangement. Algorithms extract and track the features over time and calculate position and orientation changes relative to an initial position. Output is the 3D position and orientation change measured at each image.« less

  4. Intrinsic anion oxidation potentials.

    PubMed

    Johansson, Patrik

    2006-11-01

    Anions of lithium battery salts have been investigated by electronic structure calculations with the objective to find a computational measure to correlate with the observed (in)stability of nonaqueous lithium battery electrolytes vs oxidation often encountered in practice. Accurate prediction of intrinsic anion oxidation potentials is here made possible by computing the vertical free energy difference between anion and neutral radical (Delta Gv) and further strengthened by an empirical correction using only the anion volume as a parameter. The 6-311+G(2df,p) basis set, the VSXC functional, and the C-PCM SCRF algorithm were used. The Delta Gv calculations can be performed using any standard computational chemistry software. PMID:17078600

  5. Intrinsic Feature Motion Tracking

    SciTech Connect

    Goddard, Jr., James S.

    2013-03-19

    Subject motion during 3D medical scanning can cause blurring and artifacts in the 3D images resulting in either rescans or poor diagnosis. Anesthesia or physical restraints may be used to eliminate motion but are undesirable and can affect results. This software measures the six degree of freedom 3D motion of the subject during the scan under a rigidity assumption using only the intrinsic features present on the subject area being monitored. This movement over time can then be used to correct the scan data removing the blur and artifacts. The software acquires images from external cameras or images stored on disk for processing. The images are from two or three calibrated cameras in a stereo arrangement. Algorithms extract and track the features over time and calculate position and orientation changes relative to an initial position. Output is the 3D position and orientation change measured at each image.

  6. Intrinsically variable stars

    NASA Technical Reports Server (NTRS)

    Bohm-Vitense, Erika; Querci, Monique

    1987-01-01

    The characteristics of intrinsically variable stars are examined, reviewing the results of observations obtained with the IUE satellite since its launch in 1978. Selected data on both medium-spectral-class pulsating stars (Delta Cep stars, W Vir stars, and related groups) and late-type variables (M, S, and C giants and supergiants) are presented in spectra, graphs, and tables and described in detail. Topics addressed include the calibration of the the period-luminosity relation, Cepheid distance determination, checking stellar evolution theory by the giant companions of Cepheids, Cepheid masses, the importance of the hydrogen convection zone in Cepheids, temperature and abundance estimates for Population II pulsating stars, mass loss in Population II Cepheids, SWP and LWP images of cold giants and supergiants, temporal variations in the UV lines of cold stars, C-rich cold stars, and cold stars with highly ionized emission lines.

  7. Oxidative stress and hypoxia in normal and leukemic stem cells.

    PubMed

    Testa, Ugo; Labbaye, Catherine; Castelli, Germana; Pelosi, Elvira

    2016-07-01

    The main hematopoietic stem cell (HSC) functions, self-renewal and differentiation, are finely regulated by both intrinsic mechanisms such as transcriptional and epigenetic regulators and extrinsic signals originating in the bone marrow microenvironment (HSC niche) or in the body (humoral mediators). The interaction between regulatory signals and cellular metabolism is an emerging area. Several metabolic pathways function differently in HSCs compared with progenitors and differentiated cells. Hypoxia, acting through hypoxia-inducing factors, has emerged as a key regulator of stem cell biology and acts by maintaining HSC quiescence and a condition of metabolic dormancy based on anaerobic glycolytic energetic metabolism, with consequent low production reactive oxygen species (ROS) and high antioxidant defense. Hematopoietic cell differentiation is accompanied by changes in oxidative metabolism (decrease of anaerobic glycolysis and increase of oxidative phosphorylation) and increased levels of ROS. Leukemic stem cells, defined as the cells that initiate and maintain the leukemic process, show peculiar metabolic properties in that they are more dependent on oxidative respiration than on glycolysis and are more sensitive to oxidative stress than normal HSCs. Several mitochondrial abnormalities have been described in acute myeloid leukemia (AML) cells, explaining the shift to aerobic glycolysis observed in these cells and offering the unique opportunity for therapeutic metabolic targeting. Finally, frequent mutations of the mitochondrial isocitrate dehydrogenase-2 (IDH2) enzyme are observed in AML cells, in which the mutated enzyme acts as an oncogenic driver and can be targeted using specific inhibitors under clinical evaluation with promising results. PMID:27179622

  8. Thresholds of hypoxia for marine biodiversity.

    PubMed

    Vaquer-Sunyer, Raquel; Duarte, Carlos M

    2008-10-01

    Hypoxia is a mounting problem affecting the world's coastal waters, with severe consequences for marine life, including death and catastrophic changes. Hypoxia is forecast to increase owing to the combined effects of the continued spread of coastal eutrophication and global warming. A broad comparative analysis across a range of contrasting marine benthic organisms showed that hypoxia thresholds vary greatly across marine benthic organisms and that the conventional definition of 2 mg O(2)/liter to designate waters as hypoxic is below the empirical sublethal and lethal O(2) thresholds for half of the species tested. These results imply that the number and area of coastal ecosystems affected by hypoxia and the future extent of hypoxia impacts on marine life have been generally underestimated. PMID:18824689

  9. Tissue hypoxia: implications for the respiratory clinician.

    PubMed

    MacIntyre, Neil R

    2014-10-01

    Oxygen is essential for normal aerobic metabolism in mammals. Hypoxia is the presence of lower than normal oxygen content and pressure in the cell. Causes of hypoxia include hypoxemia (low blood oxygen content and pressure), impaired oxygen delivery, and impaired cellular oxygen uptake/utilization. Many compensatory mechanisms exist at the global, regional, and cellular levels to allow cells to function in a hypoxic environment. Clinical management of tissue hypoxia usually focuses on global hypoxemia and oxygen delivery. As we move into the future, the clinical focus needs to change to assessing and managing mission-critical regional hypoxia to avoid unnecessary and potential toxic global strategies. We also need to focus on understanding and better harnessing the body's own adaptive mechanisms to hypoxia. PMID:25161296

  10. Functional alterations in macrophages after hypoxia selection.

    PubMed

    Degrossoli, Adriana; Giorgio, Selma

    2007-01-01

    Regions of low oxygen tension are common features of inflamed and infected tissues and provide physiologic selective pressure for the expansion of cells with enhanced hypoxia tolerance. The aim of this study was to investigate whether macrophages resistant to death induced by hypoxia were accompanied by functional alterations. A mouse macrophage cell line (J774 cells) was used to obtain subpopulations of death-resistant macrophages induced by long-term exposure to severe hypoxia (<1% O(2)). The results indicated that exposing J774 macrophages to periods of severe hypoxia results in the selection of cells with phenotypes associated with the modulation of heat-shock protein 70 kDa (HSP70) expression, tumor necrosis factor-alpha (TNF-alpha), and nitric oxide (NO) production and reduced susceptibility to parasite Leishmania infection. Thus, we suggest that hypoxia-selected macrophages may influence the outcome of inflammation and infection. PMID:17202589

  11. Cancer cell-associated cytoplasmic B7–H4 is induced by hypoxia through hypoxia-inducible factor-1α and promotes cancer cell proliferation

    SciTech Connect

    Jeon, You-Kyoung; Park, Sae-Gwang; Choi, Il-Whan; Lee, Soo-Woong; Lee, Sang Min

    2015-04-03

    Aberrant B7–H4 expression in cancer tissues serves as a novel prognostic biomarker for poor survival in patients with cancer. However, the factor(s) that induce cancer cell-associated B7–H4 remain to be fully elucidated. We herein demonstrate that hypoxia upregulates B7–H4 transcription in primary CD138{sup +} multiple myeloma cells and cancer cell lines. In support of this finding, analysis of the Multiple Myeloma Genomics Portal (MMGP) data set revealed a positive correlation between the mRNA expression levels of B7–H4 and the endogenous hypoxia marker carbonic anhydrogenase 9. Hypoxia-induced B7–H4 expression was detected in the cytoplasm, but not in cancer cell membranes. Chromatin immunoprecipitation analysis demonstrated binding of hypoxia-inducible factor-1α (HIF-1α) to proximal hypoxia-response element (HRE) sites within the B7–H4 promoter. Knockdown of HIF-1α and pharmacological inhibition of HIF-1α diminished B7–H4 expression. Furthermore, knockdown of cytoplasmic B7–H4 in MCF-7 decreased the S-phase cell population under hypoxia. Finally, MMGP analysis revealed a positive correlation between the transcript levels of B7–H4 and proliferation-related genes including MKI67, CCNA1, and Myc in several patients with multiple myeloma. Our results provide insight into the mechanisms underlying B7–H4 upregulation and its role in cancer cell proliferation in a hypoxic tumor microenvironment. - Highlights: • Hypoxia upregulates B7–H4 transcription and protein expression. • Hypoxia-induced B7–H4 is detected in the cytoplasm, but not on membrane. • ChIP assay reveals a binding of HIF-1α to B7–H4 promoter at HRE site. • Knockdown and pharmacological inhibition of HIF-1α reduce B7–H4 expression. • B7–H4 knockdown decrease the number of cells in S-phase of cell cycle.

  12. Curcumin improves hypoxia induced dysfunctions in 3T3-L1 adipocytes by protecting mitochondria and down regulating inflammation.

    PubMed

    Priyanka, Ariyapalli; Anusree, Sasidharan Suseela; Nisha, Vijayakumar Marykutty; Raghu, Kozhiparambil Gopalan

    2014-01-01

    Obesity induced metabolic syndrome is increasing worldwide at an alarming rate. It is characterized by excessive expansion of white adipose tissue which leads to hypoxia and impairs normal metabolism. Recent studies reveal that hypoxia could be one of the factors for inflammation, insulin resistance and other obesity related complications. There is a high demand for anti-obese phytoceuticals to control and manage the complications resulting from obesity. In this study, we investigated how hypoxia affect the physiological functions of 3T3-L1 adipocytes emphasizing on oxidative stress, inflammation, and mitochondrial functions. We also evaluated the protective role of various doses of curcumin, a well-known dietary antioxidant, on hypoxia induced alterations. The results revealed that hypoxia significantly altered the vital parameters of adipocyte biology like HIF 1α expression (103.47% ↑), lactate, and glycerol release (184.34% and 69.1% ↑, respectively), reactive oxygen species production (432.53% ↑), lipid and protein oxidation (376.6% and 566.6% ↑, respectively), reduction in antioxidant enzymes (superoxide dismutase and catalase) status, secretion of inflammatory markers (TNF α, IL 6, IL 1β, and IFN γ), and mitochondrial functions (mitochondrial mass, membrane potential, permeability transition pore integrity, and superoxide generation). Curcumin substantially protected adipocytes from toxic effects of hypoxia in a dose dependent manner by protecting mitochondria and down regulating inflammation. Acriflavine is used as a positive control. A detailed investigation is required for the development of curcumin as an effective nutraceutical against obesity. PMID:25110893

  13. Focus on the Controversial Aspects of 64Cu-ATSM in Tumoral Hypoxia Mapping by PET Imaging

    PubMed Central

    Colombié, Mathilde; Gouard, Sébastien; Frindel, Mathieu; Vidal, Aurélien; Chérel, Michel; Kraeber-Bodéré, Françoise; Rousseau, Caroline; Bourgeois, Mickaël

    2015-01-01

    Mapping tumor hypoxia is a great challenge in positron emission tomography (PET) imaging as the precise functional information of the biological processes is needed for many effective therapeutic strategies. Tumor hypoxia has been widely reported as a poor prognostic indicator and is often associated with tumor aggressiveness, chemo- and radio-resistance. An accurate diagnosis of hypoxia is a challenge and is crucial for providing accurate treatment for patients’ survival benefits. This challenge has led to the emergence of new and novel PET tracers for the functional and metabolic characterization of tumor hypoxia non-invasively. Among these tracers, copper semicarbazone compound [64Cu]-diacetyl-bis(N4-methylthiosemicarbazone) (=64Cu-ATSM) has been developed as a tracer for hypoxia imaging. This review focuses on 64Cu-ATSM PET imaging and the concept is presented in two sections. The first section describes its in vitro development and pre-clinical testing and particularly its affinity in different cell lines. The second section describes the controversial reports on its specificity for hypoxia imaging. The review concludes that 64Cu-ATSM – more than a hypoxic tracer, exhibits tracer accumulation in tumor, which is linked to the redox potential and reactive oxygen species. The authors concluded that 64Cu-ATSNM is a marker of over-reduced cell state and thus an indirect marker for hypoxia imaging. The affinity of 64Cu-ATSM for over-reduced cells was observed to be a complex phenomenon. And to provide a definitive and convincing mechanism, more in vivo studies are needed to prove the diagnostic utility of 64Cu-ATSM. PMID:26380261

  14. SUSCEPTIBILITY OF A NORTHEASTERN GULF OF MEXICO ESTUARY TO HYPOXIA

    EPA Science Inventory

    Bottom water hypoxia is a common adverse consequence of nutrient enrichment in estuaries and coastal waters. To protect against hypoxia, it is helpful to know which waters are most susceptible to hypoxia. Hypoxia has been observed regularly in Pensacola Bay, a northeastern Gulf o...

  15. p53 Dependent Apoptotic Cell Death Induces Embryonic Malformation in Carassius auratus under Chronic Hypoxia

    PubMed Central

    Dasgupta, Subrata; Sawant, Bhawesh T.; Chadha, Narinder K.; Pal, Asim K.

    2014-01-01

    Hypoxia is a global phenomenon affecting recruitment as well as the embryonic development of aquatic fauna. The present study depicts hypoxia induced disruption of the intrinsic pathway of programmed cell death (PCD), leading to embryonic malformation in the goldfish, Carrasius auratus. Constant hypoxia induced the early expression of pro-apoptotic/tumor suppressor p53 and concomitant expression of the cell death molecule, caspase-3, leading to high level of DNA damage and cell death in hypoxic embryos, as compared to normoxic ones. As a result, the former showed delayed 4 and 64 celled stages and a delay in appearance of epiboly stage. Expression of p53 efficiently switched off expression of the anti-apoptotic Bcl-2 during the initial 12 hours post fertilization (hpf) and caused embryonic cell death. However, after 12 hours, simultaneous downregulation of p53 and Caspase-3 and exponential increase of Bcl-2, caused uncontrolled cell proliferation and prevented essential programmed cell death (PCD), ultimately resulting in significant (p<0.05) embryonic malformation up to 144 hpf. Evidences suggest that uncontrolled cell proliferation after 12 hpf may have been due to downregulation of p53 abundance, which in turn has an influence on upregulation of anti-apoptotic Bcl-2. Therefore, we have been able to show for the first time and propose that hypoxia induced downregulation of p53 beyond 12 hpf, disrupts PCD and leads to failure in normal differentiation, causing malformation in gold fish embryos. PMID:25068954

  16. Intrinsically irreversible heat engine

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1984-12-25

    A class of heat engines based on an intrinsically irreversible heat transfer process is disclosed. In a typical embodiment the engine comprises a compressible fluid that is cyclically compressed and expanded while at the same time being driven in reciprocal motion by a positive displacement drive means. A second thermodynamic medium is maintained in imperfect thermal contact with the fluid and bears a broken thermodynamic symmetry with respect to the fluid. The second thermodynamic medium is a structure adapted to have a low fluid flow impedance with respect to the compressible fluid, and which is further adapted to be in only moderate thermal contact with the fluid. In operation, thermal energy is pumped along the second medium due to a phase lag between the cyclical heating and cooling of the fluid and the resulting heat conduction between the fluid and the medium. In a preferred embodiment the engine comprises an acoustical drive and a housing containing a gas which is driven at a resonant frequency so as to be maintained in a standing wave. Operation of the engine at acoustic frequencies improves the power density and coefficient of performance. The second thermodynamic medium can be coupled to suitable heat exchangers to utilize the engine as a simple refrigeration device having no mechanical moving parts. Alternatively, the engine is reversible in function so as to be utilizable as a prime mover by coupling it to suitable sources and sinks of heat. 11 figs.

  17. Intrinsically irreversible heat engine

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1984-01-01

    A class of heat engines based on an intrinsically irreversible heat transfer process is disclosed. In a typical embodiment the engine comprises a compressible fluid that is cyclically compressed and expanded while at the same time being driven in reciprocal motion by a positive displacement drive means. A second thermodynamic medium is maintained in imperfect thermal contact with the fluid and bears a broken thermodynamic symmetry with respect to the fluid. The second thermodynamic medium is a structure adapted to have a low fluid flow impedance with respect to the compressible fluid, and which is further adapted to be in only moderate thermal contact with the fluid. In operation, thermal energy is pumped along the second medium due to a phase lag between the cyclical heating and cooling of the fluid and the resulting heat conduction between the fluid and the medium. In a preferred embodiment the engine comprises an acoustical drive and a housing containing a gas which is driven at a resonant frequency so as to be maintained in a standing wave. Operation of the engine at acoustic frequencies improves the power density and coefficient of performance. The second thermodynamic medium can be coupled to suitable heat exchangers to utilize the engine as a simple refrigeration device having no mechanical moving parts. Alternatively, the engine is reversible in function so as to be utilizable as a prime mover by coupling it to suitable sources and sinks of heat.

  18. Intrinsically irreversible heat engine

    DOEpatents

    Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1984-01-01

    A class of heat engines based on an intrinsically irreversible heat transfer process is disclosed. In a typical embodiment the engine comprises a compressible fluid that is cyclically compressed and expanded while at the same time being driven in reciprocal motion by a positive displacement drive means. A second thermodynamic medium is maintained in imperfect thermal contact with the fluid and bears a broken thermodynamic symmetry with respect to the fluid. the second thermodynamic medium is a structure adapted to have a low fluid flow impedance with respect to the compressible fluid, and which is further adapted to be in only moderate thermal contact with the fluid. In operation, thermal energy is pumped along the second medium due to a phase lag between the cyclical heating and cooling of the fluid and the resulting heat conduction between the fluid and the medium. In a preferred embodiment the engine comprises an acoustical drive and a housing containing a gas which is driven at a resonant frequency so as to be maintained in a standing wave. Operation of the engine at acoustic frequencies improves the power density and coefficient of performance. The second thermodynamic medium can be coupled to suitable heat exchangers to utilize the engine as a simple refrigeration device having no mechanical moving parts. Alternatively, the engine is reversible in function so as to be utilizable as a prime mover by coupling it to suitable sources and sinks of heat.

  19. Cerebral perturbations during exercise in hypoxia.

    PubMed

    Verges, Samuel; Rupp, Thomas; Jubeau, Marc; Wuyam, Bernard; Esteve, François; Levy, Patrick; Perrey, Stéphane; Millet, Guillaume Y

    2012-04-15

    Reduction of aerobic exercise performance observed under hypoxic conditions is mainly attributed to altered muscle metabolism due to impaired O(2) delivery. It has been recently proposed that hypoxia-induced cerebral perturbations may also contribute to exercise performance limitation. A significant reduction in cerebral oxygenation during whole body exercise has been reported in hypoxia compared with normoxia, while changes in cerebral perfusion may depend on the brain region, the level of arterial oxygenation and hyperventilation induced alterations in arterial CO(2). With the use of transcranial magnetic stimulation, inconsistent changes in cortical excitability have been reported in hypoxia, whereas a greater impairment in maximal voluntary activation following a fatiguing exercise has been suggested when arterial O(2) content is reduced. Electromyographic recordings during exercise showed an accelerated rise in central motor drive in hypoxia, probably to compensate for greater muscle contractile fatigue. This accelerated development of muscle fatigue in moderate hypoxia may be responsible for increased inhibitory afferent signals to the central nervous system leading to impaired central drive. In severe hypoxia (arterial O(2) saturation <70-75%), cerebral hypoxia per se may become an important contributor to impaired performance and reduced motor drive during prolonged exercise. This review examines the effects of acute and chronic reduction in arterial O(2) (and CO(2)) on cerebral blood flow and cerebral oxygenation, neuronal function, and central drive to the muscles. Direct and indirect influences of arterial deoxygenation on central command are separated. Methodological concerns as well as future research avenues are also considered. PMID:22319046

  20. Hypoxia and metabolic adaptation of cancer cells

    PubMed Central

    Eales, K L; Hollinshead, K E R; Tennant, D A

    2016-01-01

    Low oxygen tension (hypoxia) is a pervasive physiological and pathophysiological stimulus that metazoan organisms have contended with since they evolved from their single-celled ancestors. The effect of hypoxia on a tissue can be either positive or negative, depending on the severity, duration and context. Over the long-term, hypoxia is not usually consistent with normal function and so multicellular organisms have had to evolve both systemic and cellular responses to hypoxia. Our reliance on oxygen for efficient adenosine triphosphate (ATP) generation has meant that the cellular metabolic network is particularly sensitive to alterations in oxygen tension. Metabolic changes in response to hypoxia are elicited through both direct mechanisms, such as the reduction in ATP generation by oxidative phosphorylation or inhibition of fatty-acid desaturation, and indirect mechanisms including changes in isozyme expression through hypoxia-responsive transcription factor activity. Significant regions of cancers often grow in hypoxic conditions owing to the lack of a functional vasculature. As hypoxic tumour areas contain some of the most malignant cells, it is important that we understand the role metabolism has in keeping these cells alive. This review will outline our current understanding of many of the hypoxia-induced changes in cancer cell metabolism, how they are affected by other genetic defects often present in cancers, and how these metabolic alterations support the malignant hypoxic phenotype. PMID:26807645

  1. Imaging Hypoxia in Orthotopic Rat Liver Tumors with Iodine 124–labeled Iodoazomycin Galactopyranoside PET1

    PubMed Central

    Riedl, Christopher C.; Brader, Peter; Zanzonico, Pat B.; Chun, Yun Shin; Woo, Yanghee; Singh, Paramjeet; Carlin, Sean; Wen, Bixiu; Ling, C. Clifton; Hricak, Hedvig; Fong, Yuman

    2008-01-01

    Purpose: To evaluate iodine 124 (124I)-labeled iodoazomycin galactopyranoside (IAZGP) positron emission tomography (PET) in the detection of hypoxia in an orthotopic rat liver tumor model by comparing regions of high 124I-IAZGP uptake with independent measures of hypoxia and to determine the optimal time after injection to depict hypoxia. Materials and Methods: The institutional animal care and use committee approved this study. Morris hepatoma tumors were established in the livers of 15 rats. Tumor oxygenation was measured in two rats with a fluorescence fiberoptic oxygen probe. 124I-IAZGP was coadministered with the established hypoxia markers pimonidazole and EF5 in nine rats; 12-hour PET data acquisition was performed 24 hours later. Tumor cryosections were analyzed with immunofluorescence and autoradiography. In the four remaining rats, serial 20- and 60-minute PET data acquisition was peformed up to 48 hours after tracer administration. Results: Oxygen probe measurements showed severe hypoxia (<1 mm Hg) distributed evenly throughout tumor tissue. Analysis of cryosections showed diffuse homogeneous uptake of 124I-IAZGP throughout all tumors. The 124I-IAZGP distribution correlated positively with pimonidazole (r = 0.78) and EF5 (r = 0.76) distribution. Tracer uptake in tumors was detectable with PET after 24 hours in seven of nine rats. In rats that underwent serial PET, tumor-to-liver contrast was sufficient to enable detection of hypoxia between 6 and 48 hours after tracer administration. The optimal ratio between signal intensity and tumor-to-liver contrast occurred 6 hours after tracer administration. Conclusion: Regions of high 124I-IAZGP uptake in orthotopic rat liver tumors are consistent with independent measures of hypoxia; visualization of hypoxia with 124I-IAZGP PET is optimal 6 hours after injection. © RSNA, 2008 PMID:18641253

  2. Mesenchymal stem cells protect from hypoxia-induced alveolar epithelial-mesenchymal transition.

    PubMed

    Uzunhan, Yurdagül; Bernard, Olivier; Marchant, Dominique; Dard, Nicolas; Vanneaux, Valérie; Larghero, Jérôme; Gille, Thomas; Clerici, Christine; Valeyre, Dominique; Nunes, Hilario; Boncoeur, Emilie; Planès, Carole

    2016-03-01

    Administration of bone marrow-derived human mesenchymal stem cells (hMSC) reduces lung inflammation, fibrosis, and mortality in animal models of lung injury, by a mechanism not completely understood. We investigated whether hMSC would prevent epithelial-mesenchymal transition (EMT) induced by hypoxia in primary rat alveolar epithelial cell (AEC). In AEC cultured on semipermeable filters, prolonged hypoxic exposure (1.5% O2 for up to 12 days) induced phenotypic changes consistent with EMT, i.e., a change in cell morphology, a decrease in transepithelial resistance (Rte) and in the expression of epithelial markers [zonula occludens-1 (ZO-1), E-cadherin, AQP-5, TTF-1], together with an increase in mesenchymal markers [vimentin, α-smooth muscle actin (α-SMA)]. Expression of transcription factors driving EMT such as SNAIL1, ZEB1, and TWIST1 increased after 2, 24, and 48 h of hypoxia, respectively. Hypoxia also induced TGF-β1 mRNA expression and the secretion of active TGF-β1 in apical medium, and the expression of connective tissue growth factor (CTGF), two inducers of EMT. Coculture of AEC with hMSC partially prevented the decrease in Rte and in ZO-1, E-cadherin, and TTF-1 expression, and the increase in vimentin expression induced by hypoxia. It also abolished the increase in TGF-β1 expression and in TGF-β1-induced genes ZEB1, TWIST1, and CTGF. Finally, incubation with human recombinant KGF at a concentration similar to what was measured in hMSC-conditioned media restored the expression of TTF-1 and prevented the increase in TWIST1, TGF-β1, and CTGF in hypoxic AEC. Our results indicate that hMSC prevent hypoxia-induced alveolar EMT through the paracrine modulation of EMT signaling pathways and suggest that this effect is partly mediated by KGF. PMID:26702148

  3. Structural modifications of the prostate in hypoxia, oxidative stress, and chronic ischemia

    PubMed Central

    Thurmond, Portia; Yang, Jing-Hua; Li, Yedan; Lerner, Lori B.

    2015-01-01

    Purpose Clinical studies have reported a correlation between pelvic ischemia and voiding dysfunction in elderly men. The aim of this study was to identify and compare prostate structural modifications in cultured cells and in a rabbit model after exposure to hypoxia, oxidative stress, and chronic ischemia. Materials and Methods Cultured human prostate smooth muscle cells (SMCs), epithelial cells (ECs), and stromal cells (SCs) were incubated under normoxia, hypoxia, and oxidative stress conditions by use of a computerized oxycycler system. We developed a rabbit model of chronic prostate ischemia by creating aorto-iliac arterial atherosclerosis. Markers of oxidative stress were examined by using fluorometric analysis and enzyme immunoassay. Prostate structure was examined by using Masson's trichrome staining and transmission electron microscopy (TEM). Results Lipid peroxidation was found in SMCs exposed to hypoxia and in all cell types exposed to oxidative stress. We identified protein oxidation in ECs exposed to hypoxia and in all cell types exposed to oxidative stress. Markers indicating oxidative damage were present in chronically ischemic rabbit prostate tissue. These reactions were associated with DNA damage. Prostate ischemia resulted in epithelial atrophy, loss of smooth muscle, and diffuse fibrosis. TEM showed swollen mitochondria with degraded cristae, loss of membrane, loss of Golgi bodies, degenerated nerves, and disrupted cell-to-cell junctions. Conclusions Human prostate cells exhibited differential reactions to hypoxia and oxidative stress with widespread DNA damage. Structural modifications in ischemic prostate tissue were similar to those in cells exposed to oxidative stress. Structural changes due to ischemia and oxidative stress may contribute to prostatic noncompliance in aging men. PMID:25763122

  4. Intrinsic Angular Momentum of Light.

    ERIC Educational Resources Information Center

    Santarelli, Vincent

    1979-01-01

    Derives a familiar torque-angular momentum theorem for the electromagnetic field, and includes the intrinsic torques exerted by the fields on the polarized medium. This inclusion leads to the expressions for the intrinsic angular momentum carried by the radiation traveling through a charge-free medium. (Author/MA)

  5. Targeting Artificial Tumor Stromal Targets for Molecular Imaging of Tumor Vascular Hypoxia

    PubMed Central

    Koonce, Nathan A.; Levy, Joseph; Hardee, Matthew E.; Jamshidi-Parsian, Azemat; Vang, Kieng B.; Sharma, Sunil; Raleigh, James A.; Dings, Ruud P. M.; Griffin, Robert J.

    2015-01-01

    Developed and tested for many years, a variety of tumor hypoxia detection methods have been inconsistent in their ability to predict treatment outcomes or monitor treatment efficacy, limiting their present prognostic capability. These variable results might stem from the fact that these approaches are based on inherently wide-ranging global tumor oxygenation levels based on uncertain influences of necrotic regions present in most solid tumors. Here, we have developed a novel non-invasive and specific method for tumor vessel hypoxia detection, as hypoxemia (vascular hypoxia) has been implicated as a key driver of malignant progression, therapy resistance and metastasis. This method is based on high-frequency ultrasound imaging of α-pimonidazole targeted-microbubbles to the exogenously administered hypoxia marker pimonidazole. The degree of tumor vessel hypoxia was assessed in three mouse models of mammary gland carcinoma (4T1, SCK and MMTV-Wnt-1) and amassed up to 20% of the tumor vasculature. In the 4T1 mammary gland carcinoma model, the signal strength of α-pimonidazole targeted-microbubbles was on average 8-fold fold higher in tumors of pimonidazole-injected mice than in non-pimonidazole injected tumor bearing mice or non-targeted microbubbles in pimonidazole-injected tumor bearing mice. Overall, this provides proof of principle for generating and targeting artificial antigens able to be ‘created’ on-demand under tumor specific microenvironmental conditions, providing translational diagnostic, therapeutic and treatment planning potential in cancer and other hypoxia-associated diseases or conditions. PMID:26308944

  6. The Impact of Hypoxia and Mesenchymal Transition on Glioblastoma Pathogenesis and Cancer Stem Cells Regulation.

    PubMed

    Karsy, Michael; Guan, Jian; Jensen, Randy; Huang, L Eric; Colman, Howard

    2016-04-01

    Glioblastoma (GBM) is an aggressive primary brain tumor with potential for wide dissemination and resistance to standard treatments. Although GBM represents a single histopathologic diagnosis under current World Health Organization criteria, data from multiplatform molecular profiling efforts, including The Cancer Genome Atlas, indicate that multiple subgroups with distinct markers and biology exist. It remains unclear whether treatment resistance differs based on subgroup. Recent evidence suggests that hypoxia, or absence of normal tissue oxygenation, is important in generating tumor resistance through a signaling cascade driven by hypoxia-inducible factors and vascular endothelial growth factor. Hypoxia can result in isolation of tumor cells from therapeutic agents and activation of downstream tumor protective mechanisms. In addition, there are links between hypoxia and the phenomenon of mesenchymal transition in gliomas. Mesenchymal transformation in gliomas resembles at many levels the epithelial-mesenchymal transition that has been described in other solid tumors in which epithelial cells lose their epithelial characteristics and take on a more mesenchymal phenotype, but the mesenchymal transition in brain tumors is also distinct, perhaps related to the unique cell types and cellular organization in the brain and brain tumors. Cancer stem cells, which are specific cell populations involved in self-renewal, differentiation, and GBM pathophysiology, are also importantly regulated by hypoxia signaling pathways. In this review, we discuss the interplay of hypoxia and mesenchymal signaling in GBM including the key pathway regulators and downstream genes, the effect of these processes in regulation of the tumor microenvironment and cancer stem cells, and their role in treatment resistance. PMID:26724617

  7. Targeting hypoxia in the leukemia microenvironment

    PubMed Central

    Benito, Juliana; Zeng, Zhihong; Konopleva, Marina; Wilson, William R

    2013-01-01

    SUMMARY The bone marrow (BM) microenvironment regulates survival and maintenance of normal hematopoietic stem cells. Within the endosteal niche, hypoxia has an essential role in maintenance of the primitive quiescent hematopoietic stem cell. We and others have demonstrated that in the context of hematologic malignancies the BM is highly hypoxic, and that progression of the disease is associated with expansion of hypoxic niches and stabilization of the oncogenic HIF-1α. This review will provide an overview of the normal and leukemic BM microenvironment with a special emphasis on pathological hypoxia including the development of hypoxia-activated prodrugs and their applicability in hematological malignancies. PMID:24490034

  8. Effects of hypoxia-induced neonatal seizures on acute hippocampal injury and later-life seizure susceptibility and anxiety-related behavior in mice.

    PubMed

    Rodriguez-Alvarez, Natalia; Jimenez-Mateos, Eva M; Dunleavy, Mark; Waddington, John L; Boylan, Geraldine B; Henshall, David C

    2015-11-01

    Seizures are common during the neonatal period, often due to hypoxic-ischemic encephalopathy and may contribute to acute brain injury and the subsequent development of cognitive deficits and childhood epilepsy. Here we explored short- and long-term consequences of neonatal hypoxia-induced seizures in 7 day old C57BL/6J mice. Seizure activity, molecular markers of hypoxia and histological injury were investigated acutely after hypoxia and response to chemoconvulsants and animal behaviour was explored at adulthood. Hypoxia was induced by exposing pups to 5% oxygen for 15 min (global hypoxia). Electrographically defined seizures with behavioral correlates occurred in 95% of these animals and seizures persisted for many minutes after restitution of normoxia. There was minimal morbidity or mortality. Pre- or post-hypoxia injection of phenobarbital (50mg/kg) had limited efficacy at suppressing seizures. The hippocampus from neonatal hypoxia-seizure mice displayed increased expression of vascular endothelial growth factor and the immediate early gene c-fos, minimal histological evidence of cell injury and activation of caspase-3 in scattered neurons. Behavioral analysis of mice five weeks after hypoxia-induced seizures detected novel anxiety-related and other behaviors, while performance in a spatial memory test was similar to controls. Seizure threshold tests with kainic acid at six weeks revealed that mice previously subject to neonatal hypoxia-induced seizures developed earlier, more frequent and longer-duration seizures. This study defines a set of electro-clinical, molecular, pharmacological and behavioral consequences of hypoxia-induced seizures that indicate short- and long-term deleterious outcomes and may be a useful model to investigate the pathophysiology and treatment of neonatal seizures in humans. PMID:26341542

  9. Hypoxia Promotes Glycogen Accumulation through Hypoxia Inducible Factor (HIF)-Mediated Induction of Glycogen Synthase 1

    PubMed Central

    Pescador, Nuria; Garcia-Rocha, Mar; Ortiz-Barahona, Amaya; Vazquez, Silvia; Ordoñez, Angel; Cuevas, Yolanda; Saez-Morales, David; Garcia-Bermejo, Maria Laura; Landazuri, Manuel O.; Guinovart, Joan; del Peso, Luis

    2010-01-01

    When oxygen becomes limiting, cells reduce mitochondrial respiration and increase ATP production through anaerobic fermentation of glucose. The Hypoxia Inducible Factors (HIFs) play a key role in this metabolic shift by regulating the transcription of key enzymes of glucose metabolism. Here we show that oxygen regulates the expression of the muscle glycogen synthase (GYS1). Hypoxic GYS1 induction requires HIF activity and a Hypoxia Response Element within its promoter. GYS1 gene induction correlated with a significant increase in glycogen synthase activity and glycogen accumulation in cells exposed to hypoxia. Significantly, knockdown of either HIF1α or GYS1 attenuated hypoxia-induced glycogen accumulation, while GYS1 overexpression was sufficient to mimic this effect. Altogether, these results indicate that GYS1 regulation by HIF plays a central role in the hypoxic accumulation of glycogen. Importantly, we found that hypoxia also upregulates the expression of UTP:glucose-1-phosphate urydylyltransferase (UGP2) and 1,4-α glucan branching enzyme (GBE1), two enzymes involved in the biosynthesis of glycogen. Therefore, hypoxia regulates almost all the enzymes involved in glycogen metabolism in a coordinated fashion, leading to its accumulation. Finally, we demonstrated that abrogation of glycogen synthesis, by knock-down of GYS1 expression, impairs hypoxic preconditioning, suggesting a physiological role for the glycogen accumulated during chronic hypoxia. In summary, our results uncover a novel effect of hypoxia on glucose metabolism, further supporting the central importance of metabolic reprogramming in the cellular adaptation to hypoxia. PMID:20300197

  10. [Neonatal intermittent hypoxia and hypertension].

    PubMed

    Sukhova, G K; Nozdrachev, A D; Gozal, D

    2009-01-01

    Obstructive apnea during sleep is accompanied by intermittent hypoxia (IH) leading to hypertension and other cardiovascular disturbances. A comparative evaluation of long-term effects of the neonatal IH on the cardiovascular function was performed in normotensive Sprague-Dawley and spontaneously hypertensive rats (SHR). The newborn rats were placed for 30 days to conditions of IH (8 and 21% O2, alternating every 90 s for 12 h/day). Control groups of rats were constantly kept in normoxia. By 6 months, in the spontaneously hypertensive rats submitted to IH at the period of wakefulness there was a statistically significant increase (as compared with control) of the systolic (correspondingly 185.8 +/- 1.7 and 169.9 +/- 1.4 mm Hg, p < 0.01) and diastolic pressure (correspondingly 96.2 +/- 4.9 and 86.0 +/- 2.6 mm Hg, p < 0.01). During sleep, the systolic and diastolic pressure in these rats was higher than in control animals by 10 mm Hg (p < 0.01) and 12 mm Hg (p < 0.01), its decrease during sleep being absent. SHR submitted to IH had an increase in low- to the high-frequency power ratio of the heart rate variability from 0.9 +/- 0.15 to 1.5 +/- 0.17, which indicates a shift of the sympatho-parasympathetic balance in this group towards predominance of the sympathetic component. In the Sprague-Dawley rats submitted to neonatal hypoxia, the above changes were not pronounced. These peculiarities of the hypertensive rats allow establishing connection of the genetic factor with the sympathetic mechanism providing long-term consequences of the neonatal IH for the cardiovascular control in these rats. PMID:19435263

  11. Hypoxia in relation to vasculature and proliferation in liver metastases in patients with colorectal cancer

    SciTech Connect

    Laarhoven, Hanneke W.M. van . E-mail: h.vanlaarhoven@onco.umcn.nl; Kaanders, Johannes; Lok, Jasper; Peeters, Wenny J.M.; Rijken, Paul F.J.W.; Wiering, Bastiaan; Ruers, Theo J.M.; Punt, Cornelis J.A.; Heerschap, Arend; Kogel, Albert J. van der

    2006-02-01

    Purpose: To investigate hypoxia measured by pimonidazole binding, glucose transporter 1 (GLUT1) and carbonic anhydrase IX (CA-IX) expression, proliferation, and vascularity in liver metastases of colorectal cancer and to compare GLUT1 and CA-IX expression in corresponding primary tumors. Methods and Materials: Twenty-five patients with liver metastases of colorectal cancer, planned for metastasectomy, were included. The hypoxia marker pimonidazole and proliferation marker iododeoxyuridine were administered before surgery. After immunofluorescent staining of the frozen metastases, pimonidazole binding, vascularity, and proliferation were analyzed quantitatively. Thirteen paraffin-embedded primary tumors were stained immunohistochemically for GLUT1 and CA-IX expression, which was analyzed semiquantitatively in primary tumors and corresponding liver metastases. Results: In liver metastases, pimonidazole binding showed a pattern consistent with diffusion-limited hypoxia. The mean pimonidazole-positive fraction was 0.146; the mean distance from vessels to pimonidazole-positive areas was 80 {mu}m. When expressed, often co-localization was observed between pimonidazole binding and GLUT1 or CA-IX expression, but microregional areas of mismatch were also observed. No correlation between the level of pimonidazole binding and GLUT1 or CA-IX expression was observed. In some patients, a large fraction (up to 30%) of proliferating cells was present in pimonidazole-stained areas. Expression of CA-IX in primary tumors and metastases showed a significant correlation, which was absent for GLUT1 expression. Conclusions: Compared with other tumor types, liver metastases of colorectal cancer contain large amounts of hypoxic cells. The lack of correlation with pimonidazole binding brings into question the value of GLUT1 and CA-IX as endogenous markers of hypoxia.

  12. [Assessment of fetus' hypoxia treatment with actovegin].

    PubMed

    Lominadze, A A; Sharvashidze, N K

    2006-09-01

    The condition of fetus dramatically impairs in the case of pregnancy pathologies, when uterine-placental blood circulation impairment reveals, as it happens during placental presentation followed by bleeding, chronic anemia, heart and lung diseases of mother and pneumonia. Fetus' hypoxia develops when blood circulation in the vessels of cord is impaired, placental blood circulation disorders reveal. Preventive measures of fetus intra-natal hypoxia lay in elimination of obstetric and extra-genital causes. For the treatment of fetus hypoxia the solution Actovegin 4.0+5% glucose 400.0+vitamin "C" 4.0 in dosage of 15-20 drops per minute was applied. Out of 36 pregnant patients treatment was effective in 24 cases. In 12 cases a Caesarean section was performed. In cases of fetus hypoxia Actovegin allows to transfer metabolic processes in the form of anaerobic glycolysis, thus protecting vital centers from oxygen deprivation. PMID:17057302

  13. Evaluation of Hypoxia with Cu-ATSM

    PubMed Central

    Lapi, Suzanne E.; Lewis, Jason S.; Dehdashti, Farrokh

    2015-01-01

    Imaging of hypoxia is important in many diseases states in oncology, cardiology and neurology. The radiopharmaceutical, copper labelled diacetyl-bis(N-methylthiosemicarbazone) (Cu-ATSM), has been used to assess hypoxia in many studies. In particular, Cu-ATSM has been used in oncologic settings to investigate tumor hypoxia and the role of this parameter in response to therapy and outcome. Other groups have conducted imaging studies assessing the role of hypoxia in cardiovascular disease and neurological disorders. Additionally, several groups have made significant progress into understanding the mechanism by which this compound accumulates in cells. Multiple preclinical and clinical studies have been conducted, shedding light on the important of careful image analysis when using this tracer. This review article focusses on the recent preclinical and clinical studies with this tracer. PMID:25704389

  14. Intrinsic Negative Mass from Nonlinearity

    NASA Astrophysics Data System (ADS)

    Di Mei, F.; Caramazza, P.; Pierangeli, D.; Di Domenico, G.; Ilan, H.; Agranat, A. J.; Di Porto, P.; DelRe, E.

    2016-04-01

    We propose and provide experimental evidence of a mechanism able to support negative intrinsic effective mass. The idea is to use a shape-sensitive nonlinearity to change the sign of the mass in the leading linear propagation equation. Intrinsic negative-mass dynamics is reported for light beams in a ferroelectric crystal substrate, where the diffusive photorefractive nonlinearity leads to a negative-mass Schrödinger equation. The signature of inverted dynamics is the observation of beams repelled from strongly guiding integrated waveguides irrespective of wavelength and intensity and suggests shape-sensitive nonlinearity as a basic mechanism leading to intrinsic negative mass.

  15. Neutrophil gelatinase-associated lipocalin: its response to hypoxia and association with acute mountain sickness.

    PubMed

    Mellor, Adrian; Boos, Christopher; Stacey, Mike; Hooper, Tim; Smith, Chris; Begley, Joe; Yarker, Jo; Piper, Rick; O'Hara, John; King, Rod; Turner, Steve; Woods, David R

    2013-01-01

    Acute Mountain Sickness (AMS) is a common clinical challenge at high altitude (HA). A point-of-care biochemical marker for AMS could have widespread utility. Neutrophil gelatinase-associated lipocalin (NGAL) rises in response to renal injury, inflammation and oxidative stress. We investigated whether NGAL rises with HA and if this rise was related to AMS, hypoxia or exercise. NGAL was assayed in a cohort (n = 22) undertaking 6 hours exercise at near sea-level (SL); a cohort (n = 14) during 3 hours of normobaric hypoxia (FiO2 11.6%) and on two trekking expeditions (n = 52) to over 5000 m. NGAL did not change with exercise at SL or following normobaric hypoxia. During the trekking expeditions NGAL levels (ng/ml, mean ± sd, range) rose significantly (P < 0.001) from 68 ± 14 (60-102) at 1300 m to 183 ± 107 (65-519); 143 ± 66 (60-315) and 150 ± 71 (60-357) at 3400 m, 4270 m and 5150 m respectively. At 5150 m there was a significant difference in NGAL between those with severe AMS (n = 7), mild AMS (n = 16) or no AMS (n = 23): 201 ± 34 versus 171 ± 19 versus 124 ± 12 respectively (P = 0.009 for severe versus no AMS; P = 0.026 for mild versus no AMS). In summary, NGAL rises in response to prolonged hypobaric hypoxia and demonstrates a relationship to the presence and severity of AMS. PMID:24227892

  16. PITX1, a specificity determinant in the HIF-1α-mediated transcriptional response to hypoxia

    PubMed Central

    Mudie, Sharon; Bandarra, Daniel; Batie, Michael; Biddlestone, John; Moniz, Sonia; Ortmann, Brian; Shmakova, Alena; Rocha, Sonia

    2014-01-01

    Hypoxia is an important developmental cue for multicellular organisms but it is also a contributing factor for several human pathologies, such as stroke, cardiovascular diseases and cancer. In cells, hypoxia activates a major transcriptional program coordinated by the Hypoxia Inducible Factor (HIF) family. HIF can activate more than one hundred targets but not all of them are activated at the same time, and there is considerable cell type variability. In this report we identified the paired-like homeodomain pituitary transcription factor (PITX1), as a transcription factor that helps promote specificity in HIF-1α dependent target gene activation. Mechanistically, PITX1 associates with HIF-1β and it is important for the induction of certain HIF-1 dependent genes but not all. In particular, PITX1 controls the HIF-1α-dependent expression of the histone demethylases; JMJD2B, JMJD2A, JMJD2C and JMJD1B. Functionally, PITX1 is required for the survival and proliferation responses in hypoxia, as PITX1 depleted cells have higher levels of apoptotic markers and reduced proliferation. Overall, our study identified PITX1 as a key specificity factor in HIF-1α dependent responses, suggesting PITX1 as a protein to target in hypoxic cancers. PMID:25558831

  17. Nanoparticles for Targeting Intratumoral Hypoxia: Exploiting a Potential Weakness of Glioblastoma.

    PubMed

    Aldea, Mihaela; Florian, Ioan Alexandru; Kacso, Gabriel; Craciun, Lucian; Boca, Sanda; Soritau, Olga; Florian, Ioan Stefan

    2016-09-01

    Extensive hypoxic regions are the daunting hallmark of glioblastoma, as they host aggressive stem-like cells, hinder drug delivery and shield cancer cells from the effects of radiotherapy. Nanotechnology could address most of these issues, as it employs nanoparticles (NPs) carrying drugs that selectively accumulate and achieve controlled drug release in tumor tissues. Methods overcoming the stiff interstitium and scarce vascularity within hypoxic zones include the incorporation of collagenases to degrade the collagen-rich tumor extracellular matrix, the use of multistage systems that progressively reduce NP size or of NP-loaded cells that display inherent hypoxia-targeting abilities. The unfavorable hypoxia-induced low pH could be converted into a therapeutical advantage by pH-responsive NPs or multilayer NPs, while overexpressed markers of hypoxic cells could be specifically targeted for an enhanced preferential drug delivery. Finally, promising new gene therapeutics could also be incorporated into nanovehicles, which could lead to silencing of hypoxia-specific genes that are overexpressed in cancer cells. In this review, we highlight NPs which have shown promising results in targeting cancer hypoxia and we discuss their applicability in glioblastoma, as well as possible limitations. Novel research directions in this field are also considered. PMID:27230936

  18. NOTCH3 IS ACTIVATED BY CHRONIC HYPOXIA AND CONTRIBUTES TO THE PROGRESSION OF HUMAN PROSTATE CANCER

    PubMed Central

    Danza, Giovanna; Di Serio, Claudia; Ambrosio, Maria Raffaella; Sturli, Niccolò; Lonetto, Giuseppe; Rosati, Fabiana; Rocca, Bruno Jim; Ventimiglia, Giuseppina; del Vecchio, Maria Teresa; Prudovsky, Igor; Marchionni, Niccolò; Tarantini, Francesca

    2013-01-01

    Prostate cancer is still the second cause of cancer-related death among men. Although patients with metastatic presentation have an ominous outcome, the vast majority of PCs are diagnosed at an early stage. Nonetheless, even among patients with clinically localized disease the outcome may vary considerably. Other than androgen sensitivity, little is known about which other signaling pathways are deranged in aggressive, localized cancers. The elucidation of such pathways may help to develop innovative therapies aimed at specific molecular targets. We report that in a hormone-sensitive prostate cancer cell line, LNCaP, Notch3 was activated by hypoxia and sustained cell proliferation and colony formation in soft agar. Hypoxia also modulated cellular cholesterol content and the number and size of lipid rafts, causing a coalescence of small rafts into bigger clusters; under this experimental condition Notch3 migrated from the non-raft into the raft compartment where it co-localized with the γ-secretase complex. We also looked at human prostate cancer biopsies and found that expression of Notch3 positively correlated with Gleason score and with expression of carbonic anhydrase IX, a marker of hypoxia. In conclusion, hypoxia triggers the activation of Notch3 which, in turn, sustains proliferation of prostate cancer cells. Notch3 pathway represents a promising target for adjuvant therapy in patients with prostate cancer. PMID:23729168

  19. NFAT5 Is Up-Regulated by Hypoxia: Possible Implications in Preeclampsia and Intrauterine Growth Restriction.

    PubMed

    Dobierzewska, Aneta; Palominos, Macarena; Irarrazabal, Carlos E; Sanchez, Marianela; Lozano, Mauricio; Perez-Sepulveda, Alejandra; Monteiro, Lara J; Burmeister, Yara; Figueroa-Diesel, Horacio; Rice, Gregory E; Illanes, Sebastian E

    2015-07-01

    During gestation, low oxygen environment is a major determinant of early placentation process, while persistent placental hypoxia leads to pregnancy-related complications such as preeclampsia (PE) and intrauterine growth restriction (IUGR). PE affects 5%-8% of all pregnancies worldwide and is a cause of maternal and fetal morbidity and mortality. During placental development, persistent hypoxia due to poor trophoblast invasion and reduced uteroplacental perfusion leads to maternal endothelial dysfunction and clinical manifestation of PE. Here we hypothesized that nuclear factor of activated T cells-5 (NFAT5), a well-known osmosensitive renal factor and recently characterized hypoxia-inducible protein, is also activated in vivo in placentas of PE and IUGR complications as well as in the in vitro model of trophoblast hypoxia. In JAR cells, low oxygen tension (1% O2) induced NFAT5 mRNA and increased its nuclear abundance, peaking at 16 h. This increase did not occur in parallel with the earlier HIF1A induction. Real-time PCR and Western blot analysis confirmed up-regulation of NFAT5 mRNA and NFAT5 nuclear content in human preeclamptic placentas and in rabbit placentas of an experimentally induced IUGR model, as compared with the control groups. In vitro lambda protein phosphatase (lambda PPase) treatment revealed that increased abundance of NFAT5 protein in nuclei of either JAR cells (16 h of hypoxia) or PE and IUGR placentas is at least partially due to NFAT5 phosphorylation. NFAT5 downstream targets aldose reductase (AR) and sodium-myo-inositol cotransporter (SMIT; official symbol SLC5A3) were not significantly up-regulated either in JAR cells exposed to hypoxia or in placentas of PE- and IUGR-complicated pregnancies, suggesting that hypoxia-dependent activation of NFAT5 serves as a separate function to its tonicity-dependent stimulation. In conclusion, we propose that NFAT5 may serve as a novel marker of placental hypoxia and ischemia independently of HIF1A. PMID

  20. Hypoxia on the Expression of Hepatoma Upregulated Protein in Prostate Cancer Cells

    PubMed Central

    Espinoza, Ingrid; Sakiyama, Marcelo J.; Ma, Tangeng; Fair, Logan; Zhou, Xinchun; Hassan, Mohamed; Zabaleta, Jovanny; Gomez, Christian R.

    2016-01-01

    Hepatoma upregulated protein (HURP) is a multifunctional protein with clinical promise. This protein has been demonstrated to be a predictive marker for the outcome in high-risk prostate cancer (PCa) patients, besides being a resistance factor in PCa. Although changes in oxygen tension (pO2) are associated with PCa aggressiveness, the role of hypoxia in the regulation of tumor progression genes such as HURP has not yet been described. We hypothesized that pO2 alteration is involved in the regulation of HURP expression in PCa cells. In the present study, PCa cells were incubated at 2% O2 (hypoxia) and 20% O2 (normoxia) conditions. Hypoxia reduced cell growth rate of PCa cells, when compared to the growth rate of cells cultured under normoxia (p < 0.05). The decrease in cell viability was accompanied by fivefold (p < 0.05) elevated rate of vascular endothelial growth factor (VEGF) release. The expression of VEGF and the hypoxia-inducible metabolic enzyme carbonic anhydrase 9 were elevated maximally nearly 61-fold and 200-fold, respectively (p < 0.05). Noted in two cell lines (LNCaP and C4-2B) and independent of the oxygen levels, HURP expression assessed at both mRNA and protein levels was reduced. However, the decrease was more pronounced in cells cultured under hypoxia (p < 0.05). Interestingly, the analysis of patients’ specimens by Western blot revealed a marked increase of HURP protein (fivefold), when compared to control (cystoprostatectomy) tissue (p < 0.05). Immunohistochemistry analysis showed an increase in the immunostaining intensity of HURP and the hypoxia-sensitive molecules, hypoxia-inducible factor 1-alpha (HIF-1α), VEGF, and heat-shock protein 60 (HSP60) in association with tumor grade. The data also suggested a redistribution of subcellular localization for HURP and HIF-1α from the nucleus to the cytoplasmic compartment in relation to increasing tumor grade. Analysis of HURP Promoter for HIF-1-binding sites revealed presence

  1. Reduced TIMP-2 in hypoxia enhances angiogenesis.

    PubMed

    Lahat, Nitza; Bitterman, Haim; Engelmayer-Goren, Miri; Rosenzweig, Doron; Weiss-Cerem, Lea; Rahat, Michal A

    2011-03-01

    Hypoxia, which characterizes ischemia, trauma, inflammation, and solid tumors, recruits monocytes, immobilizes them, and alters their function, leading to an anti-inflammatory and proangiogenic phenotype. Monocyte extravasation from the circulation and their migration in tissues are partially mediated by the balance between matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). The mechanisms evoked by hypoxia that regulate monocyte migration and activation are not entirely clear. Specifically, the effect of hypoxia on TIMPs in these cells has hardly been investigated. We show that hypoxia reduces TIMP-2 secretion from human primary monocytes and from the monocyte-like cell lines U937 and THP-1 by three- to fourfold (P < 0.01), by inhibiting TIMP-2 transcription through mechanisms that involve the transcription factor SP-1. Hypoxia also lowers TIMP-2 protein secretion from human endothelial cells (by 2-fold, P < 0.05). TIMP-2 levels do not influence the reduced migration of THP-1 cells in hypoxia; however, low TIMP-2 levels enhance endothelial cell migration/proliferation, their ability to form tubelike structures in vitro, and the appearance of mature blood vessels in a Matrigel plug assay in vivo. Thus we conclude that reduced TIMP-2 levels secreted from both hypoxic monocytes and endothelial cells are proangiogenic. PMID:21148412

  2. Sensing and surviving hypoxia in vertebrates.

    PubMed

    Jonz, Michael G; Buck, Leslie T; Perry, Steve F; Schwerte, Thorsten; Zaccone, Giacomo

    2016-02-01

    Surviving hypoxia is one of the most critical challenges faced by vertebrates. Most species have adapted to changing levels of oxygen in their environment with specialized organs that sense hypoxia, while only few have been uniquely adapted to survive prolonged periods of anoxia. The goal of this review is to present the most recent research on oxygen sensing, adaptation to hypoxia, and mechanisms of anoxia tolerance in nonmammalian vertebrates. We discuss the respiratory structures in fish, including the skin, gills, and air-breathing organs, and recent evidence for chemosensory neuroepithelial cells (NECs) in these tissues that initiate reflex responses to hypoxia. The use of the zebrafish as a genetic and developmental model has allowed observation of the ontogenesis of respiratory and chemosensory systems, demonstration of a putative intracellular O2 sensor in chemoreceptors that may initiate transduction of the hypoxia signal, and investigation into the effects of extreme hypoxia on cardiorespiratory development. Other organisms, such as goldfish and freshwater turtles, display a high degree of anoxia tolerance, and these models are revealing important adaptations at the cellular level, such as the regulation of glutamatergic and GABAergic neurotransmission in defense of homeostasis in central neurons. PMID:25959851

  3. Acid-sensing ion channels under hypoxia

    PubMed Central

    Yingjun, Guo; Xun, Qu

    2013-01-01

    Hypoxia represents the lack of oxygen below the basic level, and the range of known channels related to hypoxia is continually increasing. Since abnormal hypoxia initiates pathological processes in numerous diseases via, to a great degree, producing acidic microenvironment, the significance of these channels in this environment has, until now, remained completely unknown. However, recent discovery of acid-sensing ion channels (ASICs) have enhanced our understanding of the hypoxic channelome. They belong to the degenerin/epithelial Na+ channel family and function once extracellular pH decreases to a certain level. So does the ratiocination emerge that ASICs participate in many hypoxia-induced pathological processes, including pain, apoptosis, malignancy, which all appear to involve them. Since evidence suggests that activity of ASICs is altered under pathological hypoxia, future studies are needed to deeply explore the relationship between ASICs and hypoxia, which may provide a progressive understanding of hypoxic effects in cancer, arthritis, intervertebral disc degeneration, ischemic brain injury and so on. PMID:23764948

  4. Dihydroartemisinin is a Hypoxia-Active Anti-Cancer Drug in Colorectal Carcinoma Cells

    PubMed Central

    Ontikatze, Teona; Rudner, Justine; Handrick, René; Belka, Claus; Jendrossek, Verena

    2014-01-01

    Tumor hypoxia is one main biological factor that drives resistance to chemotherapy and radiotherapy. To develop a novel strategy for overcoming hypoxia-induced therapy resistance, we examined the anti-neoplastic activity of the reactive oxygen donor dihydroartemisinin (DHA) in human colon cancer cell lines in normoxia and severe hypoxia. In addition, we analyzed the involvement of the intrinsic apoptosis pathway for DHA-mediated cytotoxicity in HCT116 cells in short-term and long-term in vitro assays. When applied at lower concentrations (≤25 μM), DHA induced apoptosis in Colo205, HCT15, and HCT116 cells, whereas necrotic cell death was increased when cells were treated with higher DHA concentrations (50 μM). However, no preference for DHA-induced apoptosis or necrosis could be detected between the treatment under normoxic or hypoxic conditions. Moreover, DHA potently reduced clonogenic survival of HCT116 cells in normoxia and hypoxia. Treatment of HCT116 cells with 25 μM DHA resulted in activation of Bax under normoxic and hypoxic conditions. Interestingly, cytochrome c release from the mitochondria and caspase-activation were observed only under normoxic conditions, whereas, under hypoxic conditions DHA induced a caspase-independent apoptosis-like cell death. However, under both conditions, generation of reactive oxygen species was an important mediator of DHA-induced toxicity. Further molecular analysis suggests that DHA-mediated cell death involves different sets of pro-apoptotic Bcl-2 family members. The pronounced cytotoxic activity of DHA in severe hypoxia as well as normoxia offers new perspectives for targeting the hypoxic tumor cell fraction to improve treatment outcome for cancer patients. PMID:24904829

  5. Intrinsically disordered proteins and biomineralization.

    PubMed

    Boskey, Adele L; Villarreal-Ramirez, Eduardo

    2016-01-01

    In vertebrates and invertebrates, biomineralization is controlled by the cell and the proteins they produce. A large number of these proteins are intrinsically disordered, gaining some secondary structure when they interact with their binding partners. These partners include the component ions of the mineral being deposited, the crystals themselves, the template on which the initial crystals form, and other intrinsically disordered proteins and peptides. This review speculates why intrinsically disordered proteins are so important for biomineralization, providing illustrations from the SIBLING (small integrin binding N-glycosylated) proteins and their peptides. It is concluded that the flexible structure, and the ability of the intrinsically disordered proteins to bind to a multitude of surfaces is crucial, but details on the precise-interactions, energetics and kinetics of binding remain to be determined. PMID:26807759

  6. Intrinsic magnetization of antiferromagnetic textures

    NASA Astrophysics Data System (ADS)

    Tveten, Erlend G.; Müller, Tristan; Linder, Jacob; Brataas, Arne

    2016-03-01

    Antiferromagnets (AFMs) exhibit intrinsic magnetization when the order parameter spatially varies. This intrinsic spin is present even at equilibrium and can be interpreted as a twisting of the homogeneous AFM into a state with a finite spin. Because magnetic moments couple directly to external magnetic fields, the intrinsic magnetization can alter the dynamics of antiferromagnetic textures under such influence. Starting from the discrete Heisenberg model, we derive the continuum limit of the free energy of AFMs in the exchange approximation and explicitly rederive that the spatial variation of the antiferromagnetic order parameter is associated with an intrinsic magnetization density. We calculate the magnetization profile of a domain wall and discuss how the intrinsic magnetization reacts to external forces. We show conclusively, both analytically and numerically, that a spatially inhomogeneous magnetic field can move and control the position of domain walls in AFMs. By comparing our model to a commonly used alternative parametrization procedure for the continuum fields, we show that the physical interpretations of these fields depend critically on the choice of parametrization procedure for the discrete-to-continuous transition. This can explain why a significant amount of recent studies of the dynamics of AFMs, including effective models that describe the motion of antiferromagnetic domain walls, have neglected the intrinsic spin of the textured order parameter.

  7. The ternary complex factor net is downregulated by hypoxia and regulates hypoxia-responsive genes.

    PubMed

    Gross, Christian; Buchwalter, Gilles; Dubois-Pot, Hélène; Cler, Emilie; Zheng, Hong; Wasylyk, Bohdan

    2007-06-01

    Hypoxia and the Net ternary complex factor (TCF) regulate similar processes (angiogenesis, wound healing, and cellular migration) and genes (PAI-1, c-fos, erg-1, NOS-2, HO-1, and vascular endothelial growth factor genes), suggesting that they are involved in related pathways. We show here that hypoxia regulates Net differently from the other TCFs and that Net plays a role in the hypoxic response in vivo in mice and in cells. Hypoxia induces Net depletion from target promoters, nuclear export, ubiquitylation, and proteasomal degradation. Key mediators of the hypoxic response, the prolyl-4-hydroxylases containing domain proteins (PHDs), regulate Net. PHD downregulation in normoxia leads to Net degradation, and PHD overexpression delays Net downregulation by hypoxia. Net inhibition by RNA interference or mutation leads to altered regulation by hypoxia of the Net targets PAI-1, c-fos, and egr-1. We propose that hypoxia stimulates transcription of target promoters through removal of the repressor function of Net. Interestingly, the hematocrit response to a chemical inducer of hypoxia-like responses (cobalt chloride) is strongly altered in Net mutant mice. Our results show that the Net TCF is part of the biological response to hypoxia, adding a new component to an important pathological and physiological process. PMID:17403894

  8. Optimizing Hypoxia Detection and Treatment Strategies

    PubMed Central

    Koch, Cameron J.; Evans, Sydney M.

    2015-01-01

    Clinical studies using Eppendorf® needle sensors have invariably documented the resistance of hypoxic human tumors to therapy. These studies first documented the need for individual patient measurement of hypoxia, since hypoxia varied from tumor-to-tumor. Furthermore, hypoxia in sarcomas & cervical cancer leads to distant metastasis or local/regional spread, respectively. For various reasons, the field has moved away from direct needle-sensor oxygen measurements to indirect assays (HIF-related changes; bioreductive metabolism) and the latter can be imaged non-invasively. Many of hypoxia’s detrimental therapeutic effects are reversible in mice but little treatment-improvement in hypoxic human tumors has been seen. The question is why? What factors cause human tumors to be refractory to anti-hypoxia strategies? We suggest the primary cause to be the complexity of hypoxia formation and its characteristics. Three basic types of hypoxia exist, encompassing various diffusional (distance from perfused vessel), temporal (on/off cycling) and perfusional (blood-flow efficiency) limitations. Surprisingly, there is no current information on their relative prevalence in human tumors and even animal models. This is important because different hypoxia sub-types are predicted to require different diagnostic and therapeutic approaches, but the implications of this remain unknown. Even more challenging, no agreement exists for the best way to measure hypoxia. Some results even suggest that hypoxia is unlikely to be targetable therapeutically. In this review, the authors will revisit various critical aspects of this field that are sometimes forgotten or misrepresented in the recent literature. Since most current non-invasive imaging studies involve PET-isotope-labelled 2-nitroimidazoles, we will emphasize key findings made in our studies using EF5 [2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide] and F18-labelled EF5. These will show the importance of

  9. Hypoxia in the Northern Gulf of Mexico

    SciTech Connect

    Dale, Virginia H

    2010-01-01

    Since 1985, scientists have been documenting a hypoxic zone in the Gulf of Mexico each year. The hypoxic zone, an area of low dissolved oxygen that cannot support marine life, generally manifests itself in the spring. Since marine species either die or flee the hypoxic zone, the spread of hypoxia reduces the available habitat for marine species, which are important for the ecosystem as well as commercial and recreational fishing in the Gulf. Since 2001, the hypoxic zone has averaged 16,500 km{sup 2} during its peak summer months, an area slightly larger than the state of Connecticut, and ranged from a low of 8,500 km{sup 2} to a high of 22,000 km{sup 2}. To address the hypoxia problem, the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force (or Task Force) was formed to bring together representatives from federal agencies, states, and tribes to consider options for responding to hypoxia. The Task Force asked the White House Office of Science and Technology Policy to conduct a scientific assessment of the causes and consequences of Gulf hypoxia through its Committee on Environment and Natural Resources (CENR). In 2000 the CENR completed An Integrated Assessment: Hypoxia in the Northern Gulf of Mexico (or Integrated Assessment), which formed the scientific basis for the Task Force's Action Plan for Reducing, Mitigating, and Controlling Hypoxia in the Northern Gulf of Mexico (Action Plan, 2001). In its Action Plan, the Task Force pledged to implement ten management actions and to assess progress every 5 years. This reassessment would address the nutrient load reductions achieved, the responses of the hypoxic zone and associated water quality and habitat conditions, and economic and social effects. The Task Force began its reassessment in 2005. In 2006 as part of the reassessment, USEPA's Office of Water, on behalf of the Task Force, requested that the U.S. Environmental Protection Agency (USEPA) Science Advisory Board (SAB) convene an independent panel to

  10. [Exercise training in hypoxia prevents hypoxia induced mitochondrial DNA oxidative damage in skeletal muscle].

    PubMed

    Bo, Hai; Li, Ling; Duan, Fu-Qiang; Zhu, Jiang

    2014-10-25

    This study was undertaken to investigate the effect of exercise training on mitochondrial DNA (mtDNA) oxidative damage and 8-oxoguanine DNA glycosylase-1 (OGG1) expression in skeletal muscle of rats under continuous exposure to hypoxia. Male Sprague-Dawley rats were randomly divided into 4 groups (n = 8): normoxia control group (NC), normoxia training group (NT), hypoxia control group (HC), and hypoxia training group (HT). The hypoxia-treated animals were housed in normobaric hypoxic tent containing 11.3% oxygen for consecutive 4 weeks. The exercise-trained animals were exercised on a motor-driven rodent treadmill at a speed of 15 m/min, 5% grade for 60 min/day, 5 days per week for 4 weeks. The results showed that, compared with NC group, hypoxia attenuated complex I, II, IV and ATP synthase activities of the electron transport chain, and the level of mitochondrial membrane potential in HC group (P < 0.05 or P < 0.01). Moreover, hypoxia decreased mitochondrial OGG1, MnSOD, and GPx activities (P < 0.05 or P < 0.01), whereas elevated reactive oxygen species (ROS) generation and the level of 8-oxo-deoxyguanosine (8-oxodG) in mtDNA (P < 0.01). Furthermore, hypoxia attenuated muscle and mitochondrial [NAD⁺]/ [NADH] ratio, and SIRT3 protein expression (P < 0.05 or P < 0.01). Compared with HC group, exercise training in hypoxia elevated complex I, II, IV and ATP synthase activities, and the level of mitochondrial membrane potential in HT group (P < 0.05 or P < 0.01). Moreover, exercise training in hypoxia increased MnSOD and GPx activities and mitochondrial OGG1 level (P < 0.01), whereas decreased ROS generation and the level of 8-oxodG in mtDNA (P < 0.01). Furthermore, exercise training in hypoxia increased muscle and mitochondrial [NAD⁺]/[NADH] ratio, as well as SIRT3 protein expression (P < 0.05 or P < 0.01). These findings suggest that exercise training in hypoxia can decrease hypoxia-induced mtDNA oxidative damage in the skeletal muscle through up

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

    PubMed Central

    Ma, Zuheng; Scholz, Hanne; Björklund, Anneli; Grill, Valdemar

    2015-01-01

    Objective To provide novel insights on mitochondrial respiration in β-cells and the adaptive effects of hypoxia. Methods and Design 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. Results 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. Conclusions 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

  12. Intrinsic chemosensitivity of rostral ventrolateral medullary sympathetic premotor neurons in the in situ arterially perfused preparation of rats.

    PubMed

    Koganezawa, Tadachika; Paton, Julian F R

    2014-11-01

    Brainstem hypoperfusion is a major excitant of sympathetic activity triggering hypertension, but the exact mechanisms involved remain incompletely understood. A major source of excitatory drive to preganglionic sympathetic neurons originates from the ongoing activity of premotor neurons in the rostral ventrolateral medulla (RVLM sympathetic premotor neurons). The chemosensitivity profile of physiologically characterized RVLM sympathetic premotor neurons during hypoxia and hypercapnia remains unclear. We examined whether physiologically characterized RVLM sympathetic premotor neurons can sense brainstem ischaemia intrinsically. We addressed this issue in a unique in situ arterially perfused preparation before and after a complete blockade of fast excitatory and inhibitory synaptic transmission. During hypercapnic hypoxia, respiratory modulation of RVLM sympathetic premotor neurons was lost, but tonic firing of most RVLM sympathetic premotor neurons was elevated. After blockade of fast excitatory and inhibitory synaptic transmission, RVLM sympathetic premotor neurons continued to fire and exhibited an excitatory firing response to hypoxia but not hypercapnia. This study suggests that RVLM sympathetic premotor neurons can sustain high levels of neuronal discharge when oxygen is scarce. The intrinsic ability of RVLM sympathetic premotor neurons to maintain responsivity to brainstem hypoxia is an important mechanism ensuring adequate arterial pressure, essential for maintaining cerebral perfusion in the face of depressed ventilation and/or high cerebral vascular resistance. PMID:25016023

  13. Accumulation of Tc-99m HL91 in tumor hypoxia: in vitro cell culture and in vivo tumor model.

    PubMed

    Lee, Bi-Fang; Chiu, Nan-Tsing; Hsia, Chien-Chung; Shen, Lie-Hang

    2008-09-01

    Hypoxic cells within a tumor can account, in part, for resistance to radiotherapy and chemotherapy. Indeed, the oxygenation status has been shown to be a prognostic marker for the outcome of therapy. The purpose of this study was to determine whether Tc-99m HL91 (HL91), a noninvasive imaging tracer, detects tumor hypoxia in vitro in cell culture and in vivo in a tumor model. Uptake of HL91 in vitro into human lung cancer cells (A549) and murine Lewis lung cancer cells (LL2) was investigated at oxygen concentrations of 20% O2 (normoxia), and 1% O2 (hypoxia). HL91 biodistribution was studied in four groups: severe combined immune deficiency (SCID) mice bearing A549 tumors, C57BL/6NCrj (B6) mice bearing LL2 tumors, SCID controls, and B6 controls. Accumulation of the tracer was compared between tumors treated with hydralazine or phosphate-buffered saline (PBS). Scintigraphic images were obtained for hydralazine-treated mice and PBS-treated mice in each of the four study groups. Autoradiography of tumor slices was also acquired. In vitro studies identified hypoxia-selective uptake of HL91, with significantly increased uptake in the hypoxic state than in the normoxic state. Biodistribution and scintigraphy showed increased HL91 uptake during tumor hypoxia at 0.5 hours, and there was progressively increased activity for up to 4 hours after tracer administration. HL91 accumulation in tumor hypoxia was markedly increased in mice treated with hydralazine compared with those treated with PBS. Autoradiography revealed high HL91 uptake in the peripheral areas around the necrotic regions of the tumor, which were identified by histologic examination. HL91 exhibits selectivity for tumor hypoxia both in vitro and in vivo and provides a successful imaging modality for the detection of tumor hypoxia in vivo. PMID:19073378

  14. NADPH oxidases and reactive oxygen species at different stages of chronic hypoxia-induced pulmonary hypertension in newborn piglets

    PubMed Central

    Dennis, Kathleen E.; Aschner, J. L.; Milatovic, D.; Schmidt, J. W.; Aschner, M.; Kaplowitz, M. R.; Zhang, Y.

    2009-01-01

    Recently, we reported that reactive oxygen species (ROS) generated by NADPH oxidase (NOX) contribute to aberrant responses in pulmonary resistance arteries (PRAs) of piglets exposed to 3 days of hypoxia (Am J Physiol Lung Cell Mol Physiol 295: L881–L888, 2008). An objective of the present study was to determine whether NOX-derived ROS also contribute to altered PRA responses at a more advanced stage of pulmonary hypertension, after 10 days of hypoxia. We further wished to advance knowledge about the specific NOX and antioxidant enzymes that are altered at early and later stages of pulmonary hypertension. Piglets were raised in room air (control) or hypoxia for 3 or 10 days. Using a cannulated artery technique, we found that treatments with agents that inhibit NOX (apocynin) or remove ROS [an SOD mimetic (M40403) + polyethylene glycol-catalase] diminished responses to ACh in PRAs from piglets exposed to 10 days of hypoxia. Western blot analysis showed an increase in expression of NOX1 and the membrane fraction of p67phox. Expression of NOX4, SOD2, and catalase were unchanged, whereas expression of SOD1 was reduced, in arteries from piglets raised in hypoxia for 3 or 10 days. Markers of oxidant stress, F2-isoprostanes, measured by gas chromatography-mass spectrometry, were increased in PRAs from piglets raised in hypoxia for 3 days, but not 10 days. We conclude that ROS derived from some, but not all, NOX family members, as well as alterations in the antioxidant enzyme SOD1, contribute to aberrant PRA responses at an early and a more progressive stage of chronic hypoxia-induced pulmonary hypertension in newborn piglets. PMID:19592458

  15. Functional genomics approach to hypoxia signaling.

    PubMed

    Seta, Karen A; Millhorn, David E

    2004-02-01

    Mammalian cells require a constant supply of oxygen to maintain energy balance, and sustained hypoxia can result in cell death. It is therefore not surprising that sophisticated adaptive mechanisms have evolved that enhance cell survival during hypoxia. During the past few years, there have been a growing number of reports on hypoxia-induced transcription of specific genes. In this review, we describe a unique experimental approach that utilizes focused cDNA libraries coupled to microarray analyses to identify hypoxia-responsive signal transduction pathways and genes that confer the hypoxia-tolerant phenotype. We have used the subtractive suppression hybridization (SSH) method to create a cDNA library enriched in hypoxia-regulated genes in oxygen-sensing pheochromocytoma cells and have used this library to create microarrays that allow us to examine hundreds of genes at a time. This library contains over 300 genes and expressed sequence tags upregulated by hypoxia, including tyrosine hydroxylase, vascular endothelial growth factor, and junB. Hypoxic regulation of these and other genes in the library has been confirmed by microarray, Northern blot, and real-time PCR analyses. Coupling focused SSH libraries with microarray analyses allows one to specifically study genes relevant to a phenotype of interest while reducing much of the biological noise associated with these types of studies. When used in conjunction with high-throughput, dye-based assays for cell survival and apoptosis, this approach offers a rapid method for discovering validated therapeutic targets for the treatment of cardiovascular disease, stroke, and tumors. PMID:14715686

  16. Intrinsic Feature Pose Measurement for Awake Animal SPECT Imaging

    SciTech Connect

    Goddard Jr, James Samuel; Baba, Justin S; Lee, Seung Joon; Weisenberger, A G; Stolin, A; McKisson, J; Smith, M F

    2009-01-01

    New developments have been made in optical motion tracking for awake animal imaging that measures 3D position and orientation (pose) for a single photon emission computed tomography (SPECT) imaging system. Ongoing SPECT imaging research has been directed towards head motion measurement for brain studies in awake, unrestrained mice. In contrast to previous results using external markers, this work extracts and tracks intrinsic features from multiple camera images and computes relative pose from the tracked features over time. Motion tracking thus far has been limited to measuring extrinsic features such as retro-reflective markers applied to the mouse s head. While this approach has been proven to be accurate, the additional animal handling required to attach the markers is undesirable. A significant improvement in the procedure is achieved by measuring the pose of the head without extrinsic markers using only the external surface appearance. This approach is currently being developed with initial results presented here. The intrinsic features measurement extracts discrete, sparse natural features from 2D images such as eyes, nose, mouth and other visible structures. Stereo correspondence between features for a camera pair is determined for calculation of 3D positions. These features are also tracked over time to provide continuity for surface model fitting. Experimental results from live images are presented.

  17. Intrinsic disorder in transcription factors†

    PubMed Central

    Liu, Jiangang; Perumal, Narayanan B.; Oldfield, Christopher J.; Su, Eric W.; Uversky, Vladimir N.; Dunker, A. Keith

    2008-01-01

    Intrinsic disorder (ID) is highly abundant in eukaryotes, which reflect the greater need for disorder-associated signaling and transcriptional regulation in nucleated cells. Although several well-characterized examples of intrinsically disordered proteins in transcriptional regulation have been reported, no systematic analysis has been reported so far. To test for a general prevalence of intrinsic disorder in transcriptional regulation, we used the Predictor Of Natural Disorder Regions (PONDR) to analyze the abundance of intrinsic disorder in three transcription factor datasets and two control sets. This analysis revealed that from 94.13% to 82.63% of transcription factors posses extended regions of intrinsic disorder, relative to 54.51% and 18.64% of the proteins in two control datasets, which indicates the significant prevalence of intrinsic disorder in transcription factors. This propensity of transcription factors for intrinsic disorder was confirmed by cumulative distribution function analysis and charge-hydropathy plots. The amino acid composition analysis showed that all three transcription factor datasets were substantially depleted in order-promoting residues, and significantly enriched in disorder-promoting residues. Our analysis of the distribution of disorder within the transcription factor datasets revealed that: (a) The AT-hooks and basic regions of transcription factor DNA-binding domains are highly disordered; (b) The degree of disorder in transcription factor activation regions is much higher than that in DNA-binding domains; (c) The degree of disorder is significantly higher in eukaryotic transcription factors than in prokaryotic transcription factors; (d) The level of α-MoRFs (molecular recognition feature) prediction is much higher in transcription factors. Overall, our data reflected the fact that the eukaryotes with well-developed gene transcription machinery require transcription factor flexibility to be more efficient. PMID:16734424

  18. Expression of EGFR Under Tumor Hypoxia: Identification of a Subpopulation of Tumor Cells Responsible for Aggressiveness and Treatment Resistance

    SciTech Connect

    Hoogsteen, Ilse J.; Marres, Henri A.M.; Hoogen, Franciscus J.A. van den

    2012-11-01

    Purpose: Overexpression of epidermal growth factor receptor (EGFR) and tumor hypoxia have been shown to correlate with worse outcome in several types of cancer including head-and-neck squamous cell carcinoma. Little is known about the combination and possible interactions between the two phenomena. Methods and Materials: In this study, 45 cases of histologically confirmed squamous cell carcinomas of the head and neck were analyzed. All patients received intravenous infusions of the exogenous hypoxia marker pimonidazole prior to biopsy. Presence of EGFR, pimonidazole binding, and colocalization between EGFR and tumor hypoxia were examined using immunohistochemistry. Results: Of all biopsies examined, respectively, 91% and 60% demonstrated EGFR- and pimonidazole-positive areas. A weak but significant association was found between the hypoxic fractions of pimonidazole (HFpimo) and EGFR fractions (F-EGFR) and between F-EGFR and relative vascular area. Various degrees of colocalization between hypoxia and EGFR were found, increasing with distance from the vasculature. A high fraction of EGFR was correlated with better disease-free and metastasis-free survival, whereas a high degree of colocalization correlated with poor outcome. Conclusions: Colocalization of hypoxia and EGFR was demonstrated in head-and-neck squamous cell carcinomas, predominantly at longer distances from vessels. A large amount of colocalization was associated with poor outcome, which points to a survival advantage of hypoxic cells that are also able to express EGFR. This subpopulation of tumor cells might be indicative of tumor aggressiveness and be partly responsible for treatment resistance.

  19. Hypoxia Induces a Metabolic Shift and Enhances the Stemness and Expansion of Cochlear Spiral Ganglion Stem/Progenitor Cells

    PubMed Central

    Chen, Hsin-Chien; Lee, Jen-Tin; Shih, Cheng-Ping; Chao, Ting-Ting; Sytwu, Huey-Kang; Li, Shiue-Li; Fang, Mei-Cho; Chen, Hang-Kang; Lin, Yi-Chun; Kuo, Chao-Yin; Wang, Chih-Hung

    2015-01-01

    Previously, we demonstrated that hypoxia (1% O2) enhances stemness markers and expands the cell numbers of cochlear stem/progenitor cells (SPCs). In this study, we further investigated the long-term effect of hypoxia on stemness and the bioenergetic status of cochlear spiral ganglion SPCs cultured at low oxygen tensions. Spiral ganglion SPCs were obtained from postnatal day 1 CBA/CaJ mouse pups. The measurement of oxygen consumption rate, extracellular acidification rate (ECAR), and intracellular adenosine triphosphate levels corresponding to 20% and 5% oxygen concentrations was determined using a Seahorse XF extracellular flux analyzer. After low oxygen tension cultivation for 21 days, the mean size of the hypoxia-expanded neurospheres was significantly increased at 5% O2; this correlated with high-level expression of hypoxia-inducible factor-1 alpha (Hif-1α), proliferating cell nuclear antigen (PCNA), cyclin D1, Abcg2, nestin, and Nanog proteins but downregulated expression of p27 compared to that in a normoxic condition. Low oxygen tension cultivation tended to increase the side population fraction, with a significant difference found at 5% O2 compared to that at 20% O2. In addition, hypoxia induced a metabolic energy shift of SPCs toward higher basal ECARs and higher maximum mitochondrial respiratory capacity but lower proton leak than under normoxia, where the SPC metabolism was switched toward glycolysis in long-term hypoxic cultivation. PMID:26236724

  20. High 18F-fluorodeoxyglucose (18F-FDG) uptake in microscopic peritoneal tumors requires physiological hypoxia

    PubMed Central

    Li, Xiao-Feng; Ma, Yuanyuan; Sun, Xiaorong; Humm, John L.; Ling, C. Clifton; O’Donoghue, Joseph A.

    2010-01-01

    The objective of this study was to examine 18F-fluorodeoxyglucose (18F-FDG) uptake in microscopic tumors grown intraperitoneally in nude mice and to relate this to physiological hypoxia and glucose transporter-1 (GLUT-1) expression. Methods Human colon cancer HT29 and HCT-8 cells were injected intraperitoneally into nude mice to generate disseminated tumors of varying sizes. Following overnight fasting, animals, either breathing air or carbogen (95% O2+ 5% CO2), were intravenously administered 18F-FDG together with the hypoxia marker pimonidazole (PIMO) and the cellular proliferation marker bromodeoxyuridine (BrdUrd) one hour before sacrifice. Hoechst 33342, a perfusion marker, was administered one minute before sacrifice. Following sacrifice, the intratumoral distribution of 18F-FDG was assessed by digital autoradiography of frozen tissue sections. This was compared with the distributions of PIMO, GLUT-1 expression, BrdUrd and Hoechst 33342 as visualized by immunofluorescent microscopy. Results Small tumors (< 1 mm diameter) had high 18F-FDG accumulation and were severely hypoxic with high GLUT-1 expression. Larger tumors (1–4 mm diameter) generally had low 18F-FDG accumulation and were not significantly hypoxic with low GLUT1 expression. Carbogen breathing significantly decreased 18F-FDG accumulation and tumor hypoxia in microscopic tumors but had little effect on GLUT1 expression. Conclusion There was high 18F-FDG uptake in microscopic tumors which was spatially associated with physiological hypoxia and high GLUT-1 expression. This enhanced uptake was abrogated by carbogen breathing, indicating that in the absence of physiological hypoxia, high GLUT1 expression, by itself, was insufficient to ensure high 18F-FDG uptake. PMID:20351353

  1. Hypoxia-inducible factor-1 plays a role in phosphate-induced vascular smooth muscle cell calcification.

    PubMed

    Mokas, Sophie; Larivière, Richard; Lamalice, Laurent; Gobeil, Stéphane; Cornfield, David N; Agharazii, Mohsen; Richard, Darren E

    2016-09-01

    Medial vascular calcification is a common complication of chronic kidney disease (CKD). Although elevated inorganic phosphate stimulates vascular smooth muscle cell (VSMC) osteogenic transdifferentiation and calcification, the mechanisms involved in their calcification during CKD are not fully defined. Because hypoxic gene activation is linked to CKD and stimulates bone cell osteogenic differentiation, we used in vivo and in vitro rodent models to define the role of hypoxic signaling during elevated inorganic phosphate-induced VSMC calcification. Cell mineralization studies showed that elevated inorganic phosphate rapidly induced VSMC calcification. Hypoxia strongly enhanced elevated inorganic phosphate-induced VSMC calcification and osteogenic transdifferentiation, as seen by osteogenic marker expression. Hypoxia-inducible factor-1 (HIF-1), the key hypoxic transcription factor, was essential for enhanced VSMC calcification. Targeting HIF-1 expression in murine VSMC blocked calcification in hypoxia with elevated inorganic phosphate while HIF-1 activators, including clinically used FG-4592/Roxadustat, recreated a procalcifying environment. Elevated inorganic phosphate rapidly activated HIF-1, even in normal oxygenation; an effect mediated by HIF-1α subunit stabilization. Thus, hypoxia synergizes with elevated inorganic phosphate to enhance VSMC osteogenic transdifferentiation. Our work identifies HIF-1 as an early CKD-related pathological event, prospective marker, and potential target against vascular calcification in CKD-relevant conditions. PMID:27470678

  2. Effects of chronic intermittent hypoxia on allergen-induced airway inflammation in rats.

    PubMed

    Broytman, Oleg; Braun, Rudolf K; Morgan, Barbara J; Pegelow, David F; Hsu, Pei-Ning; Mei, Linda S; Koya, Ajay K; Eldridge, Marlowe; Teodorescu, Mihaela

    2015-02-01

    Obstructive sleep apnea aggravates asthma, but its mechanisms are unknown. Chronic intermittent hypoxia is one hallmark feature of sleep apnea. In this study, we tested the effects of chronic intermittent hypoxia on allergen-induced inflammation in rats. Four groups (n = 9-11/group) of ovalbumin (OVA)-sensitized Brown-Norway rats underwent intermittent hypoxia (10% oxygen, 30 cycles/h, 10 h/d) or normoxia for 30 days concurrent with weekly OVA or vehicle challenges. Lung physiology, differential leukocyte counts from bronchoalveolar lavage, and histology (Picro Sirius Red staining for collagen content) were compared between groups 2 days after the last challenge. Gene expression in bronchoalveolar lavage cells was quantified by quantitative PCR. Compared with normoxia, chronic intermittent hypoxia reduced the FEV0.1/FVC ratio (P = 0.005), peak expiratory flow (P = 0.002), and mean midexpiratory flow (P = 0.004), predominantly in medium and large airways; decreased the baseline eosinophil number (P = 0.01) and amplified the effect of OVA on monocyte number (P = 0.02 for the interaction); in proximal airways, increased (P = 0.008), whereas in distal airways it decreased (P = 0.004), collagen density; induced qualitative emphysematous changes in lung periphery; and increased expression of the M2 macrophage marker YM-1 and augmented OVA-induced expression of plasminogen activator inhibitor-1. Chronic intermittent hypoxia alters immune response to allergen toward a more TH-1-predominant cellular phenotype with collagen deposition and matrix degradation, leading to airflow limitation. These findings highlight the potential of sleep apnea to aggravate airway dysfunction in patients with preexistent asthma. PMID:25004109

  3. Hypoxia and Extracellular Matrix Proteins Influence Angiogenesis and Lymphangiogenesis in Mouse Embryoid Bodies

    PubMed Central

    Foskett, Andrea M.; Ezekiel, Uthayashanker R.; Trzeciakowski, Jerome P.; Zawieja, David C.; Muthuchamy, Mariappan

    2011-01-01

    Regulatory mechanisms for angiogenesis are relatively well established compared to lymphangiogenesis. Few studies have shown that a combination of vascular endothelial growth factor VEGF-A/C with hypoxia or collagen matrix promotes lymphatic structures along with blood vessel development in mouse embryoid bodies (EB). In this study we tested the hypothesis that while hypoxia combined with prolonged VEGF-A/C treatment would induce early lymphangiogenesis in addition to angiogenesis in mouse EBs, under similar conditions specific extracellular matrix (ECM) proteins would promote lymphatic vessel-like structures over angiogenesis. EBs were subjected to four conditions and were maintained under normoxia and hypoxia (21% and 2.6% O2, respectively) with or without VEGF-A/C. Microarray analyses of normoxic and hypoxic EBs, and immunofluorescence data showed very low expression of early lymphatic endothelial cell (LEC) markers, lymphatic vessel endothelial hyaluronan receptor 1 (LYVE1), and prospero-related homeobox 1 (Prox1) at early time points. Double immunofluorescence using MECA-32 and Prox1/LYVE1 demonstrated that combined hypoxia and VEGF-A/C treatment promoted formation of blood vessel-like structures, whereas only Prox1+/LYVE1+ LECs were detected in EBs at E22.5. Furthermore, EBs were grown on laminin or collagen-I coated plates and were subjected to the four treatments as described above. Results revealed that LECs in EBs at E36.5 attached better to collagen-I, resulting in an organized network of lymphatic vessel-like structures as compared to EBs grown on laminin. However, blood vessel-like structures were less favored under these same conditions. Collectively, our data demonstrate that hypoxia combined with growth factors promotes angiogenesis, whereas combination of these conditions with specific ECM proteins favors lymphangiogenesis processes in mouse EBs. PMID:22194726

  4. The efficacy of CHK1 inhibitors is not altered by hypoxia, but is enhanced after reoxygenation.

    PubMed

    Hasvold, Grete; Nähse-Kumpf, Viola; Tkacz-Stachowska, Kinga; Rofstad, Einar K; Syljuåsen, Randi G

    2013-05-01

    Inhibitors of CHK1 are in clinical trials for cancer treatment in combination with DNA-damaging agents. Importantly, it was previously suggested that hypoxic cancer cells may be particularly sensitive to CHK1 inhibition. However, this suggestion was based on studies in severe, toxic levels of hypoxia (anoxia). The influence of less severe hypoxia on the efficacy of CHK1 inhibitors, administered either as single agents or in combination with other treatments, remains to be investigated. Here, we have assayed the effects of the CHK1 inhibitors, AZD7762 and UCN-01, during various hypoxic conditions and after reoxygenation in the absence and presence of ionizing radiation. Treatment with CHK1 inhibitors during acute or prolonged hypoxia (< 0.03%, 0.2%, and 1% O2; 3 h or 20-24 h) gave similar effects on cell survival as treatment with these inhibitors during normoxia. CHK1 inhibitors combined with ionizing radiation showed similar radiosensitization in hypoxic and normoxic cells. However, when the inhibitors were administered after reoxygenation following prolonged hypoxia (< 0.03% and 0.2%; 20-24 h), we observed decreased cell survival and stronger induction of the DNA damage marker, γH2AX, in S-phase cells. This was accompanied by enhanced phosphorylation of the single-stranded DNA-binding replication protein A. These results suggest that the cytotoxic effects of CHK1 inhibitors are enhanced after reoxygenation following prolonged hypoxia, most likely due to the increased replication-associated DNA damage. Combining CHK1 inhibitors with other treatments that cause increased reoxygenation, such as fractionated radiotherapy, might therefore be beneficial. PMID:23635654

  5. Distinct physiological strategies are used to cope with constant hypoxia and intermittent hypoxia in killifish (Fundulus heteroclitus).

    PubMed

    Borowiec, Brittney G; Darcy, Kimberly L; Gillette, Danielle M; Scott, Graham R

    2015-04-15

    Many fish encounter hypoxia on a daily cycle, but the physiological effects of intermittent hypoxia are poorly understood. We investigated whether acclimation to constant (sustained) hypoxia or to intermittent diel cycles of nocturnal hypoxia (12 h normoxia:12 h hypoxia) had distinct effects on hypoxia tolerance or on several determinants of O2 transport and O2 utilization in estuarine killifish. Adult killifish were acclimated to normoxia, constant hypoxia, or intermittent hypoxia for 7 or 28 days in brackish water (4 ppt). Acclimation to both hypoxia patterns led to comparable reductions in critical O2 tension and resting O2 consumption rate, but only constant hypoxia reduced the O2 tension at loss of equilibrium. Constant (but not intermittent) hypoxia decreased filament length and the proportion of seawater-type mitochondrion-rich cells in the gills (which may reduce ion loss and the associated costs of active ion uptake), increased blood haemoglobin content, and reduced the abundance of oxidative fibres in the swimming muscle. In contrast, only intermittent hypoxia augmented the oxidative and gluconeogenic enzyme activities in the liver and increased the capillarity of glycolytic muscle, each of which should facilitate recovery between hypoxia bouts. Neither exposure pattern affected muscle myoglobin content or the activities of metabolic enzymes in the brain or heart, but intermittent hypoxia increased brain mass. We conclude that the pattern of hypoxia exposure has an important influence on the mechanisms of acclimation, and that the optimal strategies used to cope with intermittent hypoxia may be distinct from those for coping with constant hypoxia. PMID:25722002

  6. Regulation of cardiac output in hypoxia.

    PubMed

    Siebenmann, Christoph; Lundby, Carsten

    2015-12-01

    This brief review addresses the regulation of cardiac output (Q) at rest and during submaximal exercise in acute and chronic hypoxia. To preserve systemic O2 delivery in acute hypoxia Q is increased by an acceleration of heart rate, whereas stroke volume (SV) remains unchanged. Tachycardia is governed by activation of carotid and aortic chemoreceptors and a concomitant reduction in arterial baroreflex activation, all balancing sympathovagal activity toward sympathetic dominance. As hypoxia extends over several days a combination of different adaptive processes restores arterial O2 content to or beyond sea level values and hence Q normalizes. The latter however occurs as a consequence of a decrease in SV whereas tachycardia persists. The diminished SV reflects a lower left ventricular end-diastolic volume which is primarily related to hypoxia-generated reduction in plasma volume. Hypoxic pulmonary vasoconstriction may contribute by increasing right ventricular afterload and thus decreasing its ejection fraction. In summary, the Q response to hypoxia is the result of a complex interplay between several physiological mechanisms. Future studies are encouraged to establish the individual contributions of the different components from an integrative perspective. PMID:26589118

  7. Hypoxia-Inducible Factor in Thyroid Carcinoma

    PubMed Central

    Burrows, Natalie; Babur, Muhammad; Resch, Julia; Williams, Kaye J.; Brabant, Georg

    2011-01-01

    Intratumoural hypoxia (low oxygen tension) is associated with aggressive disease and poor prognosis. Hypoxia-inducible factor-1 is a transcription factor activated by hypoxia that regulates the expression of genes that promote tumour cell survival, progression, metastasis, and resistance to chemo/radiotherapy. In addition to hypoxia, HIF-1 can be activated by growth factor-signalling pathways such as the mitogen-activated protein kinases- (MAPK-) and phosphatidylinositol-3-OH kinases- (PI3K-) signalling cascades. Mutations in these pathways are common in thyroid carcinoma and lead to enhanced HIF-1 expression and activity. Here, we summarise current data that highlights the potential role of both hypoxia and MAPK/PI3K-induced HIF-1 signalling in thyroid carcinoma progression, metastatic characteristics, and the potential role of HIF-1 in thyroid carcinoma response to radiotherapy. Direct or indirect targeting of HIF-1 using an MAPK or PI3K inhibitor in combination with radiotherapy may be a new potential therapeutic target to improve the therapeutic response of thyroid carcinoma to radiotherapy and reduce metastatic burden. PMID:21765994

  8. Effects of hypoxia on vertebrate blood vessels.

    PubMed

    Russell, Michael J; Dombkowski, Ryan A; Olson, Kenneth R

    2008-03-01

    Hypoxia contracts mammalian respiratory vessels and increases vascular resistance in respiratory tissues of many vertebrates. In systemic vessels these responses vary, hypoxia relaxes mammalian vessels and contracts systemic arteries from cyclostomes. It has been proposed that hypoxic vasoconstriction in cyclostome systemic arteries is the antecedent to mammalian hypoxic pulmonary vasoconstriction, however, phylogenetic characterization of hypoxic responses is lacking. In this study, we characterized the hypoxic response of isolated systemic and respiratory vessels from a variety of vertebrates using standard myography. Pre-gill/respiratory (ventral aorta, afferent branchial artery, pulmonary artery) and post-gill/systemic (dorsal and thoracic aortas, efferent branchial artery) from lamprey (Petromyzon marinus), sandbar shark (Carcharhinus plumbeus), yellowfin tuna (Thunnus albacares), American bullfrog (Rana catesbeiana), American alligator (Alligator mississippiensis), Pekin duck (Anas platyrhynchos domesticus), chicken (Gallus domesticus) and rat (Rattus norvegicus) were exposed to hypoxia at rest or during pre-stimulation (elevated extracellular potassium, epinephrine or norepinephrine). Hypoxia produced a relaxation or transient contraction followed by relaxation in all pre-gill vessels, except for contraction in lamprey, and vasoconstriction or tri-phasic constriction-dilation-constriction in all pulmonary vessels. Hypoxia contracted systemic vessels from all animals except shark and rat and in pre-contracted rat aortas it produced a transient contraction followed by relaxation. These results show that while the classic "systemic hypoxic vasodilation and pulmonary hypoxic vasoconstriction" may occur in the microcirculation, the hypoxic response of the vertebrate macrocirculation is quite variable. These findings also suggest that hypoxic vasoconstriction is a phylogenetically ancient response. PMID:18214862

  9. Withanolide A prevents neurodegeneration by modulating hippocampal glutathione biosynthesis during hypoxia.

    PubMed

    Baitharu, Iswar; Jain, Vishal; Deep, Satya Narayan; Shroff, Sabita; Sahu, Jayanta Kumar; Naik, Pradeep Kumar; Ilavazhagan, Govindasamy

    2014-01-01

    Withania somnifera root extract has been used traditionally in ayurvedic system of medicine as a memory enhancer. Present study explores the ameliorative effect of withanolide A, a major component of withania root extract and its molecular mechanism against hypoxia induced memory impairment. Withanolide A was administered to male Sprague Dawley rats before a period of 21 days pre-exposure and during 07 days of exposure to a simulated altitude of 25,000 ft. Glutathione level and glutathione dependent free radicals scavenging enzyme system, ATP, NADPH level, γ-glutamylcysteinyl ligase (GCLC) activity and oxidative stress markers were assessed in the hippocampus. Expression of apoptotic marker caspase 3 in hippocampus was investigated by immunohistochemistry. Transcriptional alteration and expression of GCLC and Nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2) were investigated by real time PCR and immunoblotting respectively. Exposure to hypobaric hypoxia decreased reduced glutathione (GSH) level and impaired reduced gluatathione dependent free radical scavenging system in hippocampus resulting in elevated oxidative stress. Supplementation of withanolide A during hypoxic exposure increased GSH level, augmented GSH dependent free radicals scavenging system and decreased the number of caspase and hoescht positive cells in hippocampus. While withanolide A reversed hypoxia mediated neurodegeneration, administration of buthionine sulfoximine along with withanolide A blunted its neuroprotective effects. Exogenous administration of corticosterone suppressed Nrf2 and GCLC expression whereas inhibition of corticosterone synthesis upregulated Nrf2 as well as GCLC. Thus present study infers that withanolide A reduces neurodegeneration by restoring hypoxia induced glutathione depletion in hippocampus. Further, Withanolide A increases glutathione biosynthesis in neuronal cells by upregulating GCLC level through Nrf2 pathway in a corticosterone dependenet manner. PMID

  10. Withanolide A Prevents Neurodegeneration by Modulating Hippocampal Glutathione Biosynthesis during Hypoxia

    PubMed Central

    Baitharu, Iswar; Jain, Vishal; Deep, Satya Narayan; Shroff, Sabita; Sahu, Jayanta Kumar; Naik, Pradeep Kumar; Ilavazhagan, Govindasamy

    2014-01-01

    Withania somnifera root extract has been used traditionally in ayurvedic system of medicine as a memory enhancer. Present study explores the ameliorative effect of withanolide A, a major component of withania root extract and its molecular mechanism against hypoxia induced memory impairment. Withanolide A was administered to male Sprague Dawley rats before a period of 21 days pre-exposure and during 07 days of exposure to a simulated altitude of 25,000 ft. Glutathione level and glutathione dependent free radicals scavenging enzyme system, ATP, NADPH level, γ-glutamylcysteinyl ligase (GCLC) activity and oxidative stress markers were assessed in the hippocampus. Expression of apoptotic marker caspase 3 in hippocampus was investigated by immunohistochemistry. Transcriptional alteration and expression of GCLC and Nuclear factor (erythroid-derived 2)–related factor 2 (Nrf2) were investigated by real time PCR and immunoblotting respectively. Exposure to hypobaric hypoxia decreased reduced glutathione (GSH) level and impaired reduced gluatathione dependent free radical scavenging system in hippocampus resulting in elevated oxidative stress. Supplementation of withanolide A during hypoxic exposure increased GSH level, augmented GSH dependent free radicals scavenging system and decreased the number of caspase and hoescht positive cells in hippocampus. While withanolide A reversed hypoxia mediated neurodegeneration, administration of buthionine sulfoximine along with withanolide A blunted its neuroprotective effects. Exogenous administration of corticosterone suppressed Nrf2 and GCLC expression whereas inhibition of corticosterone synthesis upregulated Nrf2 as well as GCLC. Thus present study infers that withanolide A reduces neurodegeneration by restoring hypoxia induced glutathione depletion in hippocampus. Further, Withanolide A increases glutathione biosynthesis in neuronal cells by upregulating GCLC level through Nrf2 pathway in a corticosterone dependenet manner

  11. Rat reaction to hypokinesia after prior adaptation to hypoxia

    NASA Technical Reports Server (NTRS)

    Barashova, Z. I.; Tarakanova, O. I.

    1980-01-01

    The effect of prior hypoxia adaptation on body tolerance to hypokinesia was investigated. Rats trained to a 50 day period of hypokinesia and hypoxia with a preliminary month of adaptation to hypoxia showed less weight loss, higher indices for red blood content, heightened reactivity of the overall organism and the central nervous system to acute hypoxia, and decreased modification of the skeletal muscles compared to rats subjected to hypokinesia alone.

  12. Hypoxia Reduces Arylsulfatase B Activity and Silencing Arylsulfatase B Replicates and Mediates the Effects of Hypoxia

    PubMed Central

    Bhattacharyya, Sumit; Tobacman, Joanne K.

    2012-01-01

    This report presents evidence of 1) a role for arylsulfatase B (ARSB; N-acetylgalactosamine-4-sulfatase) in mediating intracellular oxygen signaling; 2) replication between the effects of ARSB silencing and hypoxia on sulfated glycosaminoglycan content, cellular redox status, and expression of hypoxia-associated genes; and 3) a mechanism whereby changes in chondroitin-4-sulfation that follow either hypoxia or ARSB silencing can induce transcriptional changes through galectin-3. ARSB removes 4-sulfate groups from the non-reducing end of chondroitin-4-sulfate and dermatan sulfate and is required for their degradation. For activity, ARSB requires modification of a critical cysteine residue by the formylglycine generating enzyme and by molecular oxygen. When primary human bronchial and human colonic epithelial cells were exposed to 10% O2×1 h, ARSB activity declined by ∼41% and ∼30% from baseline, as nuclear hypoxia inducible factor (HIF)-1α increased by ∼53% and ∼37%. When ARSB was silenced, nuclear HIF-1α increased by ∼81% and ∼61% from baseline, and mRNA expression increased to 3.73 (±0.34) times baseline. Inversely, ARSB overexpression reduced nuclear HIF-1α by ∼37% and ∼54% from baseline in the epithelial cells. Hypoxia, like ARSB silencing, significantly increased the total cellular sulfated glycosaminoglycans and chondroitin-4-sulfate (C4S) content. Both hypoxia and ARSB silencing had similar effects on the cellular redox status and on mRNA expression of hypoxia-associated genes. Transcriptional effects of both ARSB silencing and hypoxia may be mediated by reduction in galectin-3 binding to more highly sulfated C4S, since the galectin-3 that co-immunoprecipitated with C4S declined and the nuclear galectin-3 increased following ARSB knockdown and hypoxia. PMID:22428001

  13. Phylogeny of major intrinsic proteins.

    PubMed

    Danielson, Jonas A H; Johanson, Urban

    2010-01-01

    Major intrinsic proteins (MIPs) form a large superfamily of proteins that can be divided into different subfamilies and groups according to phylogenetic analyses. Plants encode more MIPs than o ther organisms and se ven subfamilies have been defined, whereofthe Nodulin26-like major intrinsic proteins (NIPs) have been shown to permeate metalloids. In this chapter we review the phylogeny of MIPs in general and especially of the plant MIPs. We also identify bacterial NIP-like MIPs and discuss the evolutionary implications of this finding regarding the origin and ancestral transport specificity of the NIPs. PMID:20666221

  14. Individual variation in whole-animal hypoxia tolerance is associated with cardiac hypoxia tolerance in a marine teleost

    PubMed Central

    Joyce, William; Ozolina, Karlina; Mauduit, Florian; Ollivier, Hélène; Claireaux, Guy

    2016-01-01

    Hypoxia is a pervasive problem in coastal environments and is predicted to have enduring impacts on aquatic ecosystems. Intraspecific variation in hypoxia tolerance is well documented in fish; however, the factors underlying this variation remain unknown. Here, we investigate the role of the heart in individual hypoxia tolerance of the European sea bass (Dicentrarchus labrax). We found individual whole-animal hypoxia tolerance is a stable trait in sea bass for more than 18 months (duration of study). We next examined in vitro cardiac performance and found myocardial muscle from hypoxia-tolerant individuals generated greater force, with higher rates of contraction and relaxation, than hypoxic-sensitive individuals during hypoxic exposure. Thus, whole-animal hypoxia tolerance is associated with cardiac hypoxia tolerance. As the occurrence of aquatic hypoxia is expected to increase in marine ecosystems, our experimental data suggest that cardiac performance may influence fish survival and distribution. PMID:26740561

  15. Hypoxia as a therapy for mitochondrial disease.

    PubMed

    Jain, Isha H; Zazzeron, Luca; Goli, Rahul; Alexa, Kristen; Schatzman-Bone, Stephanie; Dhillon, Harveen; Goldberger, Olga; Peng, Jun; Shalem, Ophir; Sanjana, Neville E; Zhang, Feng; Goessling, Wolfram; Zapol, Warren M; Mootha, Vamsi K

    2016-04-01

    Defects in the mitochondrial respiratory chain (RC) underlie a spectrum of human conditions, ranging from devastating inborn errors of metabolism to aging. We performed a genome-wide Cas9-mediated screen to identify factors that are protective during RC inhibition. Our results highlight the hypoxia response, an endogenous program evolved to adapt to limited oxygen availability. Genetic or small-molecule activation of the hypoxia response is protective against mitochondrial toxicity in cultured cells and zebrafish models. Chronic hypoxia leads to a marked improvement in survival, body weight, body temperature, behavior, neuropathology, and disease biomarkers in a genetic mouse model of Leigh syndrome, the most common pediatric manifestation of mitochondrial disease. Further preclinical studies are required to assess whether hypoxic exposure can be developed into a safe and effective treatment for human diseases associated with mitochondrial dysfunction. PMID:26917594

  16. Intrinsic and Extrinsic Motivation for Smoking Cessation.

    ERIC Educational Resources Information Center

    Curry, Susan; And Others

    1990-01-01

    Evaluated intrinsic-extrinsic model of motivation for smoking cessation using two samples (Ns=1,217 and 151) of smokers. Analysis on Reasons for Quitting scale supported intrinsic-extrinsic motivation distinction, defining four-factor model with two intrinsic and two extrinsic dimensions. Found that smokers with higher levels of intrinsic relative…

  17. The Role of Hypoxia and Cancer Stem Cells in Renal Cell Carcinoma Pathogenesis.

    PubMed

    Myszczyszyn, Adam; Czarnecka, Anna M; Matak, Damian; Szymanski, Lukasz; Lian, Fei; Kornakiewicz, Anna; Bartnik, Ewa; Kukwa, Wojciech; Kieda, Claudine; Szczylik, Cezary

    2015-12-01

    The cancer stem cell (CSC) model has recently been approached also in renal cell carcinoma (RCC). A few populations of putative renal tumor-initiating cells (TICs) were identified, but they are indifferently understood; however, the first and most thoroughly investigated are CD105-positive CSCs. The article presents a detailed comparison of all renal CSC-like populations identified by now as well as their presumable origin. Hypoxic activation of hypoxia-inducible factors (HIFs) contributes to tumor aggressiveness by multiple molecular pathways, including the governance of immature stem cell-like phenotype and related epithelial-to-mesenchymal transition (EMT)/de-differentiation, and, as a result, poor prognosis. Due to intrinsic von Hippel-Lindau protein (pVHL) loss of function, clear-cell RCC (ccRCC) develops unique pathological intra-cellular pseudo-hypoxic phenotype with a constant HIF activation, regardless of oxygen level. Despite satisfactory evidence concerning pseudo-hypoxia importance in RCC biology, its influence on putative renal CSC-like largely remains unknown. Thus, the article discusses a current knowledge of HIF-1α/2α signaling pathways in the promotion of undifferentiated tumor phenotype in general, including some experimental findings specific for pseudo-hypoxic ccRCC, mostly dependent from HIF-2α oncogenic functions. Existing gaps in understanding both putative renal CSCs and their potential connection with hypoxia need to be filled in order to propose breakthrough strategies for RCC treatment. PMID:26210994

  18. Carvacrol induces the apoptosis of pulmonary artery smooth muscle cells under hypoxia.

    PubMed

    Zhang, Qianlong; Fan, Kai; Wang, Peng; Yu, Juan; Liu, Ruxia; Qi, Hanping; Sun, Hongli; Cao, Yonggang

    2016-01-01

    The abnormal apoptosis of pulmonary artery smooth muscle cells (PASMCs) is an important pathophysiological process in pulmonary vascular remodeling and pulmonary arterial hypertension (PAH). Carvacrol, an essential oil compound from oregano and thyme, has displayed antimicrobial, antitumor, and antioxidant properties. Although carvacrol has pro-apoptosis properties in tumor cells, the underlying mechanisms of carvacrol in PASMC apoptosis remain unclear. Thus, in this study, we aim to investigate the role of carvacrol in pulmonary vascular remodeling and PASMC apoptosis in hypoxia. Right Ventricular Hypertrophy Measurements and pulmonary pathomorphology data show that the ratio of the heart weight/tibia length (HW/TL), the right ventricle/left ventricle plus septum (RV/LV+S) and the medial width of the pulmonary artery increased in chronic hypoxia and were reversed by carvacrol treatment under hypoxia. Additionally, carvacrol inhibited PASMC viability, attenuated oxidative stress, induced mitochondria membrane depolarization, increased the percentage of apoptotic cells, suppressed Bcl-2 expression, decreased procaspase-3 expression, promoted caspase-3 activation, and inhibited the ERK1/2 and PI3K/Akt pathway. Taken together, these findings suggest that carvacrol attenuates the pulmonary vascular remodeling and promotes PASMC apoptosis by acting on, at least in part, the intrinsic apoptotic pathway. This process might provide us new insight into the development of hypoxic pulmonary hypertension. PMID:26607464

  19. Endocannabinoids participate in placental apoptosis induced by hypoxia inducible factor-1.

    PubMed

    Abán, C; Martinez, N; Carou, C; Albamonte, I; Toro, A; Seyahian, A; Franchi, A; Leguizamón, G; Trigubo, D; Damiano, A; Farina, M

    2016-10-01

    During pregnancy, apoptosis is a physiological event critical in the remodeling and aging of the placenta. Increasing evidence has pointed towards the relevance of endocannabinoids (ECs) and hypoxia as modulators of trophoblast cell death. However, the relation between these factors is still unknown. In this report, we evaluated the participation of ECs in placental apoptosis induced by cobalt chloride (CoCl2), a hypoxia mimicking agent that stabilizes the expression of hypoxia inducible factor-1 alpha (HIF-1α). We found that HIF-1α stabilization decreased FAAH mRNA and protein levels, suggesting an increase in ECs tone. Additionally, CoCl2 incubation and Met-AEA treatment reduced cell viability and increased TUNEL-positive staining in syncytiotrophoblast layer. Immunohistochemical analysis demonstrated Bax and Bcl-2 protein expression in the cytoplasm of syncytiotrophoblast. Finally, HIF-1α stabilization produced an increase in Bax/Bcl-2 ratio, activation of caspase 3 and PARP cleavage. All these changes in apoptotic parameters were reversed with AM251, a CB1 antagonist. These results demonstrate that HIF-1α may induce apoptosis in human placenta via intrinsic pathway by a mechanism that involves activation of CB1 receptor suggesting a role of the ECs in this process. PMID:27488203

  20. Posterior mediastinal extramedullary hematopoiesis secondary to hypoxia

    PubMed Central

    Solazzo, A; D’Auria, V; Moccia, LG; Vatrella, A; Bocchino, M; Rea, G

    2016-01-01

    Two mediastinal masses were incidentally detected at high resolution computed tomography (HRCT) of a 72 year-old male patient, former smoker, affected by chronic obstructive pulmonary disease with worsening dyspnea and 2-year medical history of polycythemia secondary to hypoxia. Integration with a multidetector computed tomography (MDCT) scan after administration of intravenous injection contrast medium showed slightly inhomogeneous increase of enhancement of masses, suggesting in the first case potential malignancy. Diagnosis of extramedullary hematopoiesis was achieved by fine needle aspiration citology (FNAC). Extramedullary hematopoiesis must be considered in differential diagnosis in patients with medical history of polycythemia and severe hypoxia. PMID:27326388

  1. Posterior mediastinal extramedullary hematopoiesis secondary to hypoxia.

    PubMed

    Solazzo, A; D'Auria, V; Moccia, L G; Vatrella, A; Bocchino, M; Rea, G

    2016-05-01

    Two mediastinal masses were incidentally detected at high resolution computed tomography (HRCT) of a 72 year-old male patient, former smoker, affected by chronic obstructive pulmonary disease with worsening dyspnea and 2-year medical history of polycythemia secondary to hypoxia. Integration with a multidetector computed tomography (MDCT) scan after administration of intravenous injection contrast medium showed slightly inhomogeneous increase of enhancement of masses, suggesting in the first case potential malignancy. Diagnosis of extramedullary hematopoiesis was achieved by fine needle aspiration citology (FNAC). Extramedullary hematopoiesis must be considered in differential diagnosis in patients with medical history of polycythemia and severe hypoxia. PMID:27326388

  2. Reading: Intrinsic versus Extrinsic Motivation.

    ERIC Educational Resources Information Center

    Ediger, Marlow

    Much debate centers on motivating student in reading achievement. Should students feel motivated from within (intrinsic motivation), or is it better to have extrinsic motivation whereby external stimuli are used to help learners achieve optimally in reading? This paper aims to analyze the two points of view about motivating students in reading…

  3. Individual Patterns in Intrinsic Motivation.

    ERIC Educational Resources Information Center

    Hom, Harry L., Jr.; Maxwell, Frederick R.

    The effects of extrinsic reward on students' intrinsic interest was investigated using a single-subject design in a behavior disorders classroom. Baseline measures of the interest level of five children (ages 9-11 years) were collected for academic and non-academic tasks. Assessment was then made of each subject's response hierarchy or level of…

  4. Intrinsic Motivation in Physical Education

    ERIC Educational Resources Information Center

    Davies, Benjamin; Nambiar, Nathan; Hemphill, Caroline; Devietti, Elizabeth; Massengale, Alexandra; McCredie, Patrick

    2015-01-01

    This article describes ways in which educators can use Harter's perceived competence motivation theory, the achievement goal theory, and self-determination theory to develop students' intrinsic motivation to maintain physical fitness, as demonstrated by the Sound Body Sound Mind curriculum and proven effective by the 2013 University of…

  5. Improvements in Intrinsic Feature Pose Measurement for Awake Animal Imaging

    SciTech Connect

    Goddard Jr, James Samuel; Baba, Justin S; Lee, Seung Joon; Weisenberger, A G; McKisson, J; Smith, M F; Stolin, Alexander

    2010-01-01

    Development has continued with intrinsic feature optical motion tracking for awake animal imaging to measure 3D position and orientation (pose) for motion compensated reconstruction. Prior imaging results have been directed towards head motion measurement for SPECT brain studies in awake unrestrained mice. This work improves on those results in extracting and tracking intrinsic features from multiple camera images and computing pose changes from the tracked features over time. Previously, most motion tracking for 3D imaging has been limited to measuring extrinsic features such as retro-reflective markers applied to an animal s head. While this approach has been proven to be accurate, the use of external markers is undesirable for several reasons. The intrinsic feature approach has been further developed from previous work to provide full pose measurements for a live mouse scan. Surface feature extraction, matching, and pose change calculation with point tracking and accuracy results are described. Experimental pose calculation and 3D reconstruction results from live images are presented.

  6. Improvements in intrinsic feature pose measurement for awake animal imaging

    SciTech Connect

    J.S. Goddard, J.S. Baba, S.J. Lee, A.G. Weisenberger, A. Stolin, J. McKisson, M.F. Smith

    2011-06-01

    Development has continued with intrinsic feature optical motion tracking for awake animal imaging to measure 3D position and orientation (pose) for motion compensated reconstruction. Prior imaging results have been directed towards head motion measurement for SPECT brain studies in awake unrestrained mice. This work improves on those results in extracting and tracking intrinsic features from multiple camera images and computing pose changes from the tracked features over time. Previously, most motion tracking for 3D imaging has been limited to measuring extrinsic features such as retro-reflective markers applied to an animal's head. While this approach has been proven to be accurate, the use of external markers is undesirable for several reasons. The intrinsic feature approach has been further developed from previous work to provide full pose measurements for a live mouse scan. Surface feature extraction, matching, and pose change calculation with point tracking and accuracy results are described. Experimental pose calculation and 3D reconstruction results from live images are presented.

  7. Quantification of tumour vasculature and hypoxia by immunohistochemical staining and HbO2 saturation measurements.

    PubMed

    Fenton, B M; Paoni, S F; Lee, J; Koch, C J; Lord, E M

    1999-02-01

    Despite the possibility that tumour hypoxia may limit radiotherapeutic response, the underlying mechanisms remain poorly understood. A new methodology has been developed in which information from several sophisticated techniques is combined and analysed at a microregional level. First, tumour oxygen availability is spatially defined by measuring intravascular blood oxygen saturations (HbO2) cryospectrophotometrically in frozen tumour blocks. Second, hypoxic development is quantified in adjacent sections using immunohistochemical detection of a fluorescently conjugated monoclonal antibody (ELK3-51) to a nitroheterocyclic hypoxia marker (EF5), thereby providing information relating to both the oxygen consumption rates and the effective oxygen diffusion distances. Third, a combination of fluorescent (Hoechst 33342 or DiOC7(3)) and immunohistological (PECAM-1/CD31) stains is used to define the anatomical vascular densities and the fraction of blood vessels containing flow. Using a computer-interfaced microscope stage, image analysis software and a 3-CCD colour video camera, multiple images are digitized, combined to form a photo-montage and revisited after each of the three staining protocols. By applying image registration techniques, the spatial distribution of HbO2 saturations is matched to corresponding hypoxic marker intensities in adjacent sections. This permits vascular configuration to be related to oxygen availability and allows the hypoxic marker intensities to be quantitated in situ. PMID:10027314

  8. Cerebral Oxygenation in Awake Rats during Acclimation and Deacclimation to Hypoxia: An In Vivo Electron Paramagnetic Resonance Study

    PubMed Central

    Khan, Mohammad N.; Hou, Huagang G.; Merlis, Jennifer; Abajian, Michelle A.; Demidenko, Eugene; Grinberg, Oleg Y.; Swartz, Harold M.

    2011-01-01

    Abstract Dunn, J. F., N. Khan, H. G. Hou, J. Merlis, M. A. Abajian, E. Demidenko, O.Y. Grinberg, and H. M. Swartz. Cerebral oxygenation in awake rats during acclimation and deacclimation to hypoxia: an in vivo EPR study. High Alt. Med. Biol. 12:71–77, 2011.— Exposure to high altitude or hypobaric hypoxia results in a series of metabolic, physiologic, and genetic changes that serve to acclimate the brain to hypoxia. Tissue Po2 (Pto2) is a sensitive index of the balance between oxygen delivery and utilization and can be considered to represent the summation of such factors as cerebral blood flow, capillary density, hematocrit, arterial Po2, and metabolic rate. As such, it can be used as a marker of the extent of acclimation. We developed a method using electron paramagnetic resonance (EPR) to measure Pto2 in unanesthetized subjects with a chronically implanted sensor. EPR was used to measure rat cortical tissue Pto2 in awake rats during acute hypoxia and over a time course of acclimation and deacclimation to hypobaric hypoxia. This was done to simulate the effects on brain Pto2 of traveling to altitude for a limited period. Acute reduction of inspired O2 to 10% caused a decline from 26.7 ± 2.2 to 13.0 ± 1.5 mmHg (mean ± SD). Addition of 10% CO2 to animals breathing 10% O2 returned Pto2 to values measured while breathing 21% O2, indicating that hypercapnia can reverse the effects of acute hypoxia. Pto2 in animals acclimated to 10% O2 was similar to that measured preacclimation when breathing 21% O2. Using a novel, individualized statistical model, it was shown that the T1/2 of the Pto2 response during exposure to chronic hypoxia was approximately 2 days. This indicates a capacity for rapid adaptation to hypoxia. When subjects were returned to normoxia, there was a transient hyperoxygenation, followed by a return to lower values with a T1/2 of deacclimation of 1.5 to 3 days. These data indicate that exposure to hypoxia results in significant

  9. Hypoxia inducible factor pathway inhibitors as anticancer therapeutics

    PubMed Central

    Burroughs, Sarah K; Kaluz, Stefan; Wang, Danzhu; Wang, Ke

    2013-01-01

    Hypoxia is a significant feature of solid tumor cancers. Hypoxia leads to a more malignant phenotype that is resistant to chemotherapy and radiation, is more invasive and has greater metastatic potential. Hypoxia activates the hypoxia inducible factor (HIF) pathway, which mediates the biological effects of hypoxia in tissues. The HIF complex acts as a transcription factor for many genes that increase tumor survival and proliferation. To date, many HIF pathway inhibitors indirectly affect HIF but there have been no clinically approved direct HIF inhibitors. This can be attributed to the complexity of the HIF pathway, as well as to the challenges of inhibiting protein–protein interactions. PMID:23573973

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

    PubMed

    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

    2016-01-01

    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. PMID:27500522

  11. O2.04TREATMENT WITH OMX-4.80, A TUMOR-PENETRATING TUNABLE OXYGEN CARRIER, REDUCES TUMOR HYPOXIA AND DRAMATICALLY ENHANCES RADIATION THERAPY IN INTRACRANIAL MODELS OF GLIOBLASTOMA

    PubMed Central

    Krtolica, A.; Le Moan, N.; Serwer, L.; Yoshida, Y.; Ozawa, T.; Butowski, N.; James, D.; Cary, S.

    2014-01-01

    We have developed OMX-4.80, a tunable oxygen carrier from the H-NOX protein family, that preferentially accumulates in tumor tissue, reduces hypoxia and enhances radiotherapy (RT). Tumor hypoxia is associated with poor patient outcomes in multiple solid tumors including glioblastoma (GB) and is thought to be a major contributor to poor cancer responses to chemo and radiation therapy. Here, we show that OMX-4.80 administered i.v. into the tail vein of mice bearing orthotopic GB passes the blood-tumor barrier, penetrates deep into intracranial tumors, and significantly reduces tumor hypoxia in a dose-dependent manner. Hypoxia reduction is demonstrated by a significant decrease in levels of hypoxia inducible factor, HIF1α, and the external hypoxia marker pimonidazole as assessed by IHC and image analysis. Furthermore, hypoxia before and after treatment is compared in the individual tumors by concurrent immunostaining of tumors with a long-term hypoxia marker, Glut1, and short-lived HIF-1α. These data reveal >50% reduction in hypoxic tumor area after OMX-4.80 treatment confirming the effectiveness of OMX-4.80 in reducing hypoxia in individual tumors. When OMX-4.80 treatment was coupled with a single high dose of RT, we observed a 2.7-fold increase in tumor growth delay and 2.9-fold longer survival (p < 0.05, by logrank). Toxicology studies in rodents and dogs with single and multiple supratherapeutic doses of OMX-4.80 revealed a good safety profile affirming its suitability for clinical development. In conclusion, our results indicate that OMX-4.80 is an effective and promising RT enhancer that warrants clinical development in GB patients.

  12. Targeting tumour hypoxia to prevent cancer metastasis. From biology, biosensing and technology to drug development: the METOXIA consortium.

    PubMed

    Pettersen, Erik O; Ebbesen, Peter; Gieling, Roben G; Williams, Kaye J; Dubois, Ludwig; Lambin, Philippe; Ward, Carol; Meehan, James; Kunkler, Ian H; Langdon, Simon P; Ree, Anne H; Flatmark, Kjersti; Lyng, Heidi; Calzada, Maria J; Peso, Luis Del; Landazuri, Manuel O; Görlach, Agnes; Flamm, Hubert; Kieninger, Jochen; Urban, Gerald; Weltin, Andreas; Singleton, Dean C; Haider, Syed; Buffa, Francesca M; Harris, Adrian L; Scozzafava, Andrea; Supuran, Claudiu T; Moser, Isabella; Jobst, Gerhard; Busk, Morten; Toustrup, Kasper; Overgaard, Jens; Alsner, Jan; Pouyssegur, Jacques; Chiche, Johanna; Mazure, Nathalie; Marchiq, Ibtissam; Parks, Scott; Ahmed, Afshan; Ashcroft, Margaret; Pastorekova, Silvia; Cao, Yihai; Rouschop, Kasper M; Wouters, Brad G; Koritzinsky, Marianne; Mujcic, Hilda; Cojocari, Dan

    2015-01-01

    The hypoxic areas of solid cancers represent a negative prognostic factor irrespective of which treatment modality is chosen for the patient. Still, after almost 80 years of focus on the problems created by hypoxia in solid tumours, we still largely lack methods to deal efficiently with these treatment-resistant cells. The consequences of this lack may be serious for many patients: Not only is there a negative correlation between the hypoxic fraction in tumours and the outcome of radiotherapy as well as many types of chemotherapy, a correlation has been shown between the hypoxic fraction in tumours and cancer metastasis. Thus, on a fundamental basis the great variety of problems related to hypoxia in cancer treatment has to do with the broad range of functions oxygen (and lack of oxygen) have in cells and tissues. Therefore, activation-deactivation of oxygen-regulated cascades related to metabolism or external signalling are important areas for the identification of mechanisms as potential targets for hypoxia-specific treatment. Also the chemistry related to reactive oxygen radicals (ROS) and the biological handling of ROS are part of the problem complex. The problem is further complicated by the great variety in oxygen concentrations found in tissues. For tumour hypoxia to be used as a marker for individualisation of treatment there is a need for non-invasive methods to measure oxygen routinely in patient tumours. A large-scale collaborative EU-financed project 2009-2014 denoted METOXIA has studied all the mentioned aspects of hypoxia with the aim of selecting potential targets for new hypoxia-specific therapy and develop the first stage of tests for this therapy. A new non-invasive PET-imaging method based on the 2-nitroimidazole [(18)F]-HX4 was found to be promising in a clinical trial on NSCLC patients. New preclinical models for testing of the metastatic potential of cells were developed, both in vitro (2D as well as 3D models) and in mice (orthotopic grafting

  13. Dynamic regulation of metabolic efficiency explains tolerance to acute hypoxia in humans.

    PubMed

    Schiffer, Tomas A; Ekblom, Björn; Lundberg, Jon O; Weitzberg, Eddie; Larsen, Filip J

    2014-10-01

    The maximum power principle dictates that open biological systems tend to self-organize to a level of efficiency that allows maximal power production. Applying this principle to cellular energetics and whole-body physiology would suggest that for every metabolic challenge, an optimal efficiency exists that maximizes power production. On exposure to hypoxia, it would be favorable if metabolic efficiency would rapidly adjust so as to better preserve work performance. We tested this idea in humans by measuring metabolic efficiency and exercise tolerance under normoxic (Fio2=20.9%) and hypoxic (Fio2=16%) conditions, where Fio2 is fraction of inhaled oxygen. The results were compared with respirometric analyses of skeletal muscle mitochondria from the same individuals. We found that among healthy trained subjects (n=14) with a wide range of metabolic efficiency (ME), those with a high ME during normoxic exercise were able to better maintain exercise capacity (Wmax) in hypoxia. On hypoxic exposure, these subjects acutely decreased their efficiency from 19.2 to 17.4%, thereby likely shifting it closer to a degree of efficiency where maximal power production is achieved. In addition, mitochondria from these subjects had a lower intrinsic respiration compared to subjects that showed a large drop in Wmax in hypoxia An acute shift in efficiency was also demonstrated in isolated mitochondria exposed to physiological levels of hypoxia as P/O ratio increased from 0.9 to 1.3 with hypoxic exposure. These findings suggest the existence of a physiological adaptive response by which metabolic efficiency is dynamically optimized to maximize power production. PMID:24970395

  14. Hypoxia-induced alveolar epithelial-mesenchymal transition requires mitochondrial ROS and hypoxia-inducible factor 1

    PubMed Central

    Zhou, Guofei; Dada, Laura A.; Wu, Minghua; Kelly, Aileen; Trejo, Humberto; Zhou, Qiyuan; Varga, John

    2009-01-01

    Patients with acute lung injury develop hypoxia, which may lead to lung dysfunction and aberrant tissue repair. Recent studies have suggested that epithelial-mesenchymal transition (EMT) contributes to pulmonary fibrosis. We sought to determine whether hypoxia induces EMT in alveolar epithelial cells (AEC). We found that hypoxia induced the expression of α-smooth muscle actin (α-SMA) and vimentin and decreased the expression of E-cadherin in transformed and primary human, rat, and mouse AEC, suggesting that hypoxia induces EMT in AEC. Both severe hypoxia and moderate hypoxia induced EMT. The reactive oxygen species (ROS) scavenger Euk-134 prevented hypoxia-induced EMT. Moreover, hypoxia-induced expression of α-SMA and vimentin was prevented in mitochondria-deficient ρ0 cells, which are incapable of ROS production during hypoxia. CoCl2 and dimethyloxaloylglycine, two compounds that stabilize hypoxia-inducible factor (HIF)-α under normoxia, failed to induce α-SMA expression in AEC. Furthermore, overexpression of constitutively active HIF-1α did not induce α-SMA. However, loss of HIF-1α or HIF-2α abolished induction of α-SMA mRNA during hypoxia. Hypoxia increased the levels of transforming growth factor (TGF)-β1, and preincubation of AEC with SB431542, an inhibitor of the TGF-β1 type I receptor kinase, prevented the hypoxia-induced EMT, suggesting that the process was TGF-β1 dependent. Furthermore, both ROS and HIF-α were necessary for hypoxia-induced TGF-β1 upregulation. Accordingly, we have provided evidence that hypoxia induces EMT of AEC through mitochondrial ROS, HIF, and endogenous TGF-β1 signaling. PMID:19801454

  15. Imaging Hypoxia in Xenografted and Murine Tumors With {sup 18}F-Fluoroazomycin Arabinoside: A Comparative Study Involving MICROPET, Autoradiography, PO{sub 2}-Polarography, and Fluorescence Microscopy

    SciTech Connect

    Busk, Morten Horsman, Michael R.; Jakobsen, Steen; Keiding, Susanne; Kogel, Albert J. van der; Bussink, Johan; Overgaard, Jens

    2008-03-15

    Purpose: Positron emission tomography (PET) allows noninvasive assessment of tumor hypoxia; however the combination of low resolution and slow tracer clearance from nonhypoxic tissue is problematic. The aim of this study was to examine the in vivo hypoxia selectivity of fluoroazomycin arabinoside ([{sup 18}F]-FAZA), a promising tracer with improved washout kinetics from oxygenated tissue. Methods and Materials: Three squamous cell carcinomas and one fibrosarcoma with widely differing spatial patterns of vascularization, hypoxia, and necrosis were grown in mice and evaluated with PET and complementary methods. Results: Eppendorf electrode measurements consistently demonstrated median PO{sub 2} values <1 mm Hg. In accordance with that, PET revealed that all tumors accumulated [{sup 18}F]-FAZA in excess of reference tissue. Next the two-dimensional spatial distribution of [{sup 18}F]-FAZA (from autoradiography) was compared with fluorescence images of the same tumor sections showing localization of the hypoxia marker pimonidazole and the perfusion marker Hoechst 33342. Pixel-by-pixel analysis of co-registered images showed a highly significant co-localization between the two hypoxia markers and an inverse correlation (except for the fibrosarcoma) between the distribution of [{sup 18}F]-FAZA and Hoechst dye. Moreover intratumoral heterogeneity in tracer distribution was clearly visible on autoradiograms, with a [{sup 18}F]-FAZA concentration approximately six times higher in poorly oxygenated areas than in vascular hot spots. Conclusions: The distribution of [{sup 18}F]-FAZA is consistent with hypoxia as the key driving force for tracer tissue retention in a selection of tumors with widely differing physiology.

  16. Discourse Markers across Language.

    ERIC Educational Resources Information Center

    Fraser, Bruce

    This paper discusses discourse markers (e.g., "and, so, anyway") and offers an overview of their characteristics and occurrence, using English for illustration. The role of discourse markers is to signal speaker comment on the current utterance. The discourse marker is not part of the sentence's propositional content. While absence of markers does…

  17. Pre- and Perinatal Ischemia-Hypoxia, the Ischemia-Hypoxia Response Pathway, and ADHD Risk.

    PubMed

    Smith, Taylor F; Schmidt-Kastner, Rainald; McGeary, John E; Kaczorowski, Jessica A; Knopik, Valerie S

    2016-05-01

    This review focuses on how measured pre- and perinatal environmental and (epi)genetic risk factors are interrelated and potentially influence one, of many, common developmental pathway towards ADHD. Consistent with the Developmental Origins of Health and Disease hypothesis, lower birth weight is associated with increased ADHD risk. Prenatal ischemia-hypoxia (insufficient blood and oxygen supply in utero) is a primary pathway to lower birth weight and produces neurodevelopmental risk for ADHD. To promote tissue survival in the context of ischemia-hypoxia, ischemia-hypoxia response (IHR) pathway gene expression is altered in the developing brain and peripheral tissues. Although altered IHR gene expression is adaptive in the context of ischemia-hypoxia, lasting IHR epigenetic modifications may lead to increased ADHD risk. Taken together, IHR genetic vulnerability to ischemia-hypoxia and IHR epigenetic alterations following prenatal ischemia-hypoxia may result in neurodevelopmental vulnerability for ADHD. Limitations of the extant literature and future directions for genetically-informed research are discussed. PMID:26920003

  18. Cardiovascular and cerebrovascular responses to acute hypoxia following exposure to intermittent hypoxia in healthy humans

    PubMed Central

    Foster, Glen E; Brugniaux, Julien V; Pialoux, Vincent; Duggan, Cailean T C; Hanly, Patrick J; Ahmed, Sofia B; Poulin, Marc J

    2009-01-01

    Intermittent hypoxia (IH) is thought to be responsible for many of the long-term cardiovascular consequences associated with obstructive sleep apnoea (OSA). Experimental human models of IH can aid in investigating the pathophysiology of these cardiovascular complications. The purpose of this study was to determine the effects of IH on the cardiovascular and cerebrovascular response to acute hypoxia and hypercapnia in an experimental human model that simulates the hypoxaemia experienced by OSA patients. We exposed 10 healthy, male subjects to IH for 4 consecutive days. The IH profile involved 2 min of hypoxia (nadir = 45.0 mmHg) alternating with 2 min of normoxia (peak = 88.0 mmHg) for 6 h. The cerebral blood flow response and the pressor responses to hypoxia and hypercapnia were assessed after 2 days of sham exposure, after each day of IH, and 4 days following the discontinuation of IH. Nitric oxide derivatives were measured at baseline and following the last exposure to IH. After 4 days of IH, mean arterial pressure increased by 4 mmHg (P < 0.01), nitric oxide derivatives were reduced by 55% (P < 0.05), the pressor response to acute hypoxia increased (P < 0.01), and the cerebral vascular resistance response to hypoxia increased (P < 0.01). IH alters blood pressure and cerebrovascular regulation, which is likely to contribute to the pathogenesis of cardiovascular and cerebrovascular disease in patients with OSA. PMID:19417094

  19. Multimodality imaging of hypoxia in preclinical settings

    PubMed Central

    Mason, Ralph P.; Zhao, Dawen; Pacheco-Torres, Jesús; Cui, Weina; Kodibagkar, Vikram D.; Gulaka, Praveen K.; Hao, Guiyang; Thorpe, Philip; Hahn, Eric W.; Peschke, Peter

    2011-01-01

    Hypoxia has long been recognized to influence solid tumor response to therapy. Increasingly, hypoxia has also been implicated in tumor aggressiveness, including growth, development and metastatic potential. Thus, there is a fundamental, as well as a clinical interest, in assessing in situ tumor hypoxia. This review will examine diverse approaches focusing on the pre-clinical setting, particularly, in rodents. The strategies are inevitably a compromise in terms of sensitivity, precision, temporal and spatial resolution, as well as cost, feasibility, ease and robustness of implementation. We will review capabilities of multiple modalities and examine what makes them particularly suitable for investigating specific aspects of tumor pathophysiology. Current approaches range from nuclear imaging to magnetic resonance and optical, with varying degrees of invasiveness and ability to examine spatial heterogeneity, as well as dynamic response to interventions. Ideally, measurements would be non-invasive, exploiting endogenous reporters to reveal quantitatively local oxygen tension dynamics. A primary focus of this review is magnetic resonance imaging (MRI) based techniques, such as 19F MRI oximetry, which reveals not only hypoxia in vivo, but more significantly, spatial distribution of pO2 quantitatively, with a precision relevant to radiobiology. It should be noted that pre-clinical methods may have very different criteria for acceptance, as compared with potential investigations for prognostic radiology or predictive biomarkers suitable for use in patients. PMID:20639813

  20. GULF OF MEXICO HYPOXIA MONITORING AND MODELING

    EPA Science Inventory

    Greene, Richard M. and Russell G. Kreis. In press. Gulf of Mexico Hypoxia Monitoring and Modeling (Abstract). To be presented at the EPA Science Forum: Healthy Communities and Ecosystems, 1-3 June 2004, Washington, DC. 1 p. (ERL,GB R990).

    Oxygen-depleted or hypoxic bottom...

  1. Molecular mechanisms regulating macrophage response to hypoxia.

    PubMed

    Rahat, Michal A; Bitterman, Haim; Lahat, Nitza

    2011-01-01

    Monocytes and Macrophages (Mo/Mɸ) exhibit great plasticity, as they can shift between different modes of activation and, driven by their immediate microenvironment, perform divergent functions. These include, among others, patrolling their surroundings and maintaining homeostasis (resident Mo/Mɸ), combating invading pathogens and tumor cells (classically activated or M1 Mo/Mɸ), orchestrating wound healing (alternatively activated or M2 Mo/Mɸ), and restoring homeostasis after an inflammatory response (resolution Mɸ). Hypoxia is an important factor in the Mɸ microenvironment, is prevalent in many physiological and pathological conditions, and is interdependent with the inflammatory response. Although Mo/Mɸ have been studied in hypoxia, the mechanisms by which hypoxia influences the different modes of their activation, and how it regulates the shift between them, remain unclear. Here we review the current knowledge about the molecular mechanisms that mediate this hypoxic regulation of Mɸ activation. Much is known about the hypoxic transcriptional regulatory network, which includes the master regulators hypoxia-induced factor-1 and NF-κB, as well as other transcription factors (e.g., AP-1, Erg-1), but we also highlight the role of post-transcriptional and post-translational mechanisms. These mechanisms mediate hypoxic induction of Mɸ pro-angiogenic mediators, suppress M1 Mɸ by post-transcriptionally inhibiting pro-inflammatory mediators, and help shift the classically activated Mɸ into an activation state which approximate the alternatively activated or resolution Mɸ. PMID:22566835

  2. Acridine-intercalator based hypoxia selective cytotoxins

    DOEpatents

    Papadopoulou-Rosenzweig, Maria; Bloomer, William D.; Bloomer, William D.

    1994-01-01

    Hypoxia selective cytotoxins of the general formula ##STR1## wherein n is from 1 to 5, and NO.sub.2 is in at least one of the 2, 4 or 5-positions of the imidazole. Such compounds have utility as radiosensitizers and chemosensitizers.

  3. Molecular Mechanisms Regulating Macrophage Response to Hypoxia

    PubMed Central

    Rahat, Michal A.; Bitterman, Haim; Lahat, Nitza

    2011-01-01

    Monocytes and Macrophages (Mo/Mɸ) exhibit great plasticity, as they can shift between different modes of activation and, driven by their immediate microenvironment, perform divergent functions. These include, among others, patrolling their surroundings and maintaining homeostasis (resident Mo/Mɸ), combating invading pathogens and tumor cells (classically activated or M1 Mo/Mɸ), orchestrating wound healing (alternatively activated or M2 Mo/Mɸ), and restoring homeostasis after an inflammatory response (resolution Mɸ). Hypoxia is an important factor in the Mɸ microenvironment, is prevalent in many physiological and pathological conditions, and is interdependent with the inflammatory response. Although Mo/Mɸ have been studied in hypoxia, the mechanisms by which hypoxia influences the different modes of their activation, and how it regulates the shift between them, remain unclear. Here we review the current knowledge about the molecular mechanisms that mediate this hypoxic regulation of Mɸ activation. Much is known about the hypoxic transcriptional regulatory network, which includes the master regulators hypoxia-induced factor-1 and NF-κB, as well as other transcription factors (e.g., AP-1, Erg-1), but we also highlight the role of post-transcriptional and post-translational mechanisms. These mechanisms mediate hypoxic induction of Mɸ pro-angiogenic mediators, suppress M1 Mɸ by post-transcriptionally inhibiting pro-inflammatory mediators, and help shift the classically activated Mɸ into an activation state which approximate the alternatively activated or resolution Mɸ. PMID:22566835

  4. Acridine-intercalator based hypoxia selective cytotoxins

    DOEpatents

    Papadopoulou-Rosenzweig, M.; Bloomer, W.D.

    1994-03-15

    Hypoxia selective cytotoxins of the general formula STR1 wherein n is from 1 to 5, and NO[sub 2] is in at least one of the 2, 4 or 5-positions of the imidazole are developed. Such compounds have utility as radiosensitizers and chemosensitizers. 9 figs.

  5. New Approaches to the Gulf Hypoxia Problem

    NASA Astrophysics Data System (ADS)

    Bianchi, Thomas S.; Allison, Mead A.; Chapman, Piers; Cowan, James H.; Dagg, Michael J.; Day, John W.; DiMarco, Steve F.; Hetland, Robert D.; Powell, Rodney

    2010-05-01

    Coastal water hypoxia, where dissolved oxygen is less than 2 milligrams per liter, is a global environmental problem [e.g., Diaz and Rosenberg, 2008]. It is largely associated with eutrophication, whereby nutrient inputs (nitrogen and phosphorous) to coastal waters lead to elevated primary production and accelerated rates of microbial respiration, which results in oxygen depletion. Despite more than 25 years of monitoring [Rabalais et al., 2007] (see also Figure S1 in the online supplement to this Eos issue (http://www.agu.org/eos_elec/)), the relative importance of the various processes that control hypoxia in bottom waters of the northern Gulf of Mexico (GOM)—in particular, those beyond the direct influence of river plumes [Dagg et al., 2007; Bianchi et al., 2008, 2010, and references therein]—remains uncertain. For example, a prediction last June pronounced that the 2009 hypoxic area would be the largest on record (˜23,000 square kilometers; see http://www.gulfhypoxia.net/Research/Shelfwide%20Cruises/2009/Files/2009_Hypoxia_Forecast.pdf). However, the most recent annual surveys estimated its size at 8000 square kilometers, only 35% of that predicted. This occurred in the absence of a significant hurricane impact on this margin in 2009—hurricanes tend to dissipate hypoxia.

  6. Increased SCF/c-kit by hypoxia promotes autophagy of human placental chorionic plate-derived mesenchymal stem cells via regulating the phosphorylation of mTOR.

    PubMed

    Lee, Youjin; Jung, Jieun; Cho, Kyung Jin; Lee, Seoung-Kwan; Park, Jong-Wan; Oh, Il-Hoan; Kim, Gi Jin

    2013-01-01

    Hypoxia triggers physiological and pathological cellular processes, including proliferation, differentiation, and death, in several cell types. Mesenchymal stem cells (MSCs) derived from various tissues have self-renewal activity and can differentiate towards multiple lineages. Recently, it has been reported that hypoxic conditions tip the balance between survival and death by hypoxia-induced autophagy, although the underlying mechanism is not clear. The objectives of this study are to compare the effect of hypoxia on the self-renewal of bone marrow-derived mesenchymal stem cells (BM-MSCs) and placental chorionic plate-derived mesenchymal stem cells (CP-MSCs) and to investigate the regulatory mechanisms of self-renewal in each MSC type during hypoxia. The expression of self-renewal markers (e.g., Oct4, Nanog, Sox2) was assessed in both cell lines. PI3K and stem cell factor (SCF) expression gradually increased in CP-MSCs but were markedly downregulated in BM-MSCs by hypoxia. The phosphorylation of ERK and mTOR was augmented by hypoxia in CP-MSCs compared to control. Also, the expression of LC3 II, a component of the autophagosome and the hoof-shaped autophagosome was detected more rapidly in CP-MSCs than in BM-MSCs under hypoxia. Hypoxia induced the expression of SCF in CP-MSCs and increased SCF/c-kit pathway promotes the self-renewal activities of CP-MSCs via an autocrine/paracrine mechanism that balances cell survival and cell death events by autophagy. These activities occur to a greater extent in CP-MSCs than in BM-MSCs through regulating the phosphorylation of mTOR. These findings will provide useful guidelines for better understanding the function of SCF/c-kit in the self-renewal and autophagy-regulated mechanisms that promote of MSC survival. PMID:22833529

  7. Ethyl 3,4-dihydroxybenzoate (EDHB): a prolyl hydroxylase inhibitor attenuates acute hypobaric hypoxia mediated vascular leakage in brain.

    PubMed

    Singh, Deependra Pratap; Nimker, Charu; Paliwal, Piyush; Bansal, Anju

    2016-07-01

    Sudden exposure to altitude hypoxia is responsible for acute mountain sickness (AMS) in un-acclimatized persons. If not treated in time, AMS can worsen and leads to high altitude cerebral edema, which can be fatal. Present study explores the efficacy of ethyl 3,4-dihydroxybenzoate (EDHB), a prolyl hydroxylase enzyme inhibitor, in modulating adaptive responses to hypobaric hypoxia (HH) in rat brain. Male Sprague-Dawley rats treated with EDHB (75 mg/kg for 3 days), were subjected to acute HH exposure at 9144 m (30,000 ft) for 5 h. Animals were assessed for transvascular leakage and edema formation in brain and role of key inflammatory markers along with hypoxia responsive genes. HH stress increased transvascular permeability and edema formation in conjunction with upregulation of nuclear factor-κB (NF-κB) and its regulated proteins. There was surge in pro-inflammatory cytokines tumor necrosis factor-α, interleukin-6, interferon-γ, monocyte chemoattractant protein-1 and decrement in anti-inflammatory cytokine interleukin-10. Further, upregulation of vascular endothelial growth factor (VEGF), a vascular permeability marker and down-regulation of antioxidant and anti-inflammatory proteins hemoxygenase (HO-1) and metallothionein (MT-1) was also observed under hypoxia. EDHB supplementation effectively scaled down HH induced cerebral edema with concomitant downregulation of brain NF-κB expression. There was significant curtailment of pro-inflammatory cytokines and cell adhesion molecules. There was significant downregulation of permeability factor VEGF by EDHB with concomitant increment in hypoxia inducible factor (HIF1α) and anti-inflammatory proteins HO-1 and MT-1 compared to HH control thus accentuating the potential of EDHB as effective hypoxic preconditioning agent in ameliorating HH mediated injury in brain. PMID:26649730

  8. Cyclosporine Treatment Reduces Oxygen Free Radical Generation and Oxidative Stress in the Brain of Hypoxia-Reoxygenated Newborn Piglets

    PubMed Central

    Liu, Jiang-Qin; Chaudhary, Hetal; Brocks, Dion R.; Bigam, David L.; Cheung, Po-Yin

    2012-01-01

    Oxygen free radicals have been implicated in the pathogenesis of hypoxic-ischemic encephalopathy. It has previously been shown in traumatic brain injury animal models that treatment with cyclosporine reduces brain injury. However, the potential neuroprotective effect of cyclosporine in asphyxiated neonates has yet to be fully studied. Using an acute newborn swine model of hypoxia-reoxygenation, we evaluated the effects of cyclosporine on the brain, focusing on hydrogen peroxide (H2O2) production and markers of oxidative stress. Piglets (1–4 d, 1.4–2.5 kg) were block-randomized into three hypoxia-reoxygenation experimental groups (2 h hypoxia followed by 4 h reoxygenation)(n = 8/group). At 5 min after reoxygenation, piglets were given either i.v. saline (placebo, controls) or cyclosporine (2.5 or 10 mg/kg i.v. bolus) in a blinded-randomized fashion. An additional sham-operated group (n = 4) underwent no hypoxia-reoxygenation. Systemic hemodynamics, carotid arterial blood flow (transit-time ultrasonic probe), cerebral cortical H2O2 production (electrochemical sensor), cerebral tissue glutathione (ELISA) and cytosolic cytochrome-c (western blot) levels were examined. Hypoxic piglets had cardiogenic shock (cardiac output 40–48% of baseline), hypotension (mean arterial pressure 27–31 mmHg) and acidosis (pH 7.04) at the end of 2 h of hypoxia. Post-resuscitation cyclosporine treatment, particularly the higher dose (10 mg/kg), significantly attenuated the increase in cortical H2O2 concentration during reoxygenation, and was associated with lower cerebral oxidized glutathione levels. Furthermore, cyclosporine treatment significantly attenuated the increase in cortical cytochrome-c and lactate levels. Carotid blood arterial flow was similar among groups during reoxygenation. Conclusively, post-resuscitation administration of cyclosporine significantly attenuates H2O2 production and minimizes oxidative stress in newborn piglets following hypoxia

  9. Pancreatic Fibroblasts Stimulate the Motility of Pancreatic Cancer Cells through IGF1/IGF1R Signaling under Hypoxia

    PubMed Central

    Hirakawa, Toshiki; Yashiro, Masakazu; Doi, Yosuke; Kinoshita, Haruhito; Morisaki, Tamami; Fukuoka, Tatsunari; Hasegawa, Tsuyoshi; Kimura, Kenjiro; Amano, Ryosuke; Hirakawa, Kosei

    2016-01-01

    Pancreatic ductal adenocarcinoma (PDAC) is characterized by its hypovascularity, with an extremely poor prognosis because of its highly invasive nature. PDAC proliferates with abundant stromal cells, suggesting that its invasive activity might be controlled by intercellular interactions between cancer cells and fibroblasts. Using four PDAC cell lines and two pancreas cancer-associated fibroblasts (CAFs), the expression of insulin-like growth factor-1 (IGF1) and IGF1 receptor (IGF1R) was evaluated by RT-PCR, FACScan, western blot, or ELISA. Correlation between IGF1R and the hypoxia marker carbonic anhydrase 9 (CA9) was examined by immunohistochemical staining of 120 pancreatic specimens. The effects of CAFs, IGF1, and IGF1R inhibitors on the motility of cancer cells were examined by wound-healing assay or invasion assay under normoxia (20% O2) and hypoxia (1% O2). IGF1R expression was significantly higher in RWP-1, MiaPaCa-2, and OCUP-AT cells than in Panc-1 cells. Hypoxia increased the expression level of IGF1R in RWP-1, MiaPaCa-2, and OCUP-AT cells. CA9 expression was correlated with IGF1R expression in pancreatic specimens. CAFs produced IGF1 under hypoxia, but PDAC cells did not. A conditioned medium from CAFs, which expressed αSMA, stimulated the migration and invasion ability of MiaPaCa-2, RWP-1, and OCUP-AT cells. The motility of all PDAC cells was greater under hypoxia than under normoxia. The motility-stimulating ability of CAFs was decreased by IGF1R inhibitors. These findings might suggest that pancreas CAFs stimulate the invasion activity of PDAC cells through paracrine IGF1/IGF1R signaling, especially under hypoxia. Therefore the targeting of IGF1R signaling might represent a promising therapeutic approach in IGF1R-dependent PDAC. PMID:27487118

  10. Hypoxia-Inducible Factor 1–Dependent Induction of Intestinal Trefoil Factor Protects Barrier Function during Hypoxia

    PubMed Central

    Furuta, Glenn T.; Turner, Jerrold R.; Taylor, Cormac T.; Hershberg, Robert M.; Comerford, Katrina; Narravula, Sailaja; Podolsky, Daniel K.; Colgan, Sean P.

    2001-01-01

    Mucosal organs such as the intestine are supported by a rich and complex underlying vasculature. For this reason, the intestine, and particularly barrier-protective epithelial cells, are susceptible to damage related to diminished blood flow and concomitant tissue hypoxia. We sought to identify compensatory mechanisms that protect epithelial barrier during episodes of intestinal hypoxia. Initial studies examining T84 colonic epithelial cells revealed that barrier function is uniquely resistant to changes elicited by hypoxia. A search for intestinal-specific, barrier-protective factors revealed that the human intestinal trefoil factor (ITF) gene promoter bears a previously unappreciated binding site for hypoxia-inducible factor (HIF)-1. Hypoxia resulted in parallel induction of ITF mRNA and protein. Electrophoretic mobility shift assay analysis using ITF-specific, HIF-1 consensus motifs resulted in a hypoxia-inducible DNA binding activity, and loading cells with antisense oligonucleotides directed against the α chain of HIF-1 resulted in a loss of ITF hypoxia inducibility. Moreover, addition of anti-ITF antibody resulted in a loss of barrier function in epithelial cells exposed to hypoxia, and the addition of recombinant human ITF to vascular endothelial cells partially protected endothelial cells from hypoxia-elicited barrier disruption. Extensions of these studies in vivo revealed prominent hypoxia-elicited increases in intestinal permeability in ITF null mice. HIF-1–dependent induction of ITF may provide an adaptive link for maintenance of barrier function during hypoxia. PMID:11342587

  11. [Intrinsically Photosensitive Retinal Ganglion Cells].

    PubMed

    Skorkovská, K; Skorkovská, Š

    2015-06-01

    Recently discovered intrinsically photosensitive melanopsin-containing retinal ganglion cells contribute to circadian photoentrainment and pupillary constriction; recent works have also brought new evidence for their accessory role in the visual system in humans. Pupil light reaction driven by individual photoreceptors can be isolated by means of the so called chromatic pupillography. The use of chromatic stimuli to elicit different pupillary responses may become an objective clinical pupil test in the detection of retinal diseases and in assessing new therapeutic approaches particularly in hereditary retinal degenerations like retinitis pigmentosa. In advanced stages of disease, the pupil light reaction is even more sensitive than standard electroretinography for detecting residual levels of photoreceptor activity. This review summarizes current knowledge on intrinsically photosensitive retinal cells and highlights its possible implications for clinical practice. PMID:26201360

  12. Long-term adaptation to hypoxia preserves hematopoietic stem cell function.

    PubMed

    Chen, Jichun; Kang, Ju-Gyeong; Keyvanfar, Keyvan; Young, Neal S; Hwang, Paul M

    2016-09-01

    Molecular oxygen sustains aerobic life, but it also serves as the substrate for oxidative stress, which has been associated with the pathogenesis of disease and with aging. Compared with mice housed in normoxia (21% O2), reducing ambient oxygen to 10% O2 (hypoxia) resulted in increased hematopoietic stem cell (HSC) function as measured by bone marrow (BM) cell engraftment onto lethally irradiated recipients. The number of BM c-Kit(+)Sca-1(+)Lin(-) (KSL) cells as well as the number of cells with other hematopoietic stem and progenitor cell markers were increased in hypoxia mice, whereas the BM cells' colony-forming capacity remained unchanged. KSL cells from hypoxia mice showed a decreased level of oxidative stress and increased expression of transcription factor Gata1 and cytokine receptor c-Mpl, consistent with the observations of increased erythropoiesis and enhanced HSC engraftment. These observations demonstrate the benefit of a hypoxic HSC niche and suggest that hypoxic conditions can be further optimized to preserve stem cell integrity in vivo. PMID:27118043

  13. Intrinsic Control of Axon Regeneration.

    PubMed

    He, Zhigang; Jin, Yishi

    2016-05-01

    A determinant of axon regeneration is the intrinsic growth ability of injured neurons, which dictates a battery of injury responses in axons and cell bodies. While some of these regulatory mechanisms are evolutionarily conserved, others are unique to the mammalian central nervous system (CNS) where spontaneous regeneration usually does not occur. Here we examine our current understanding of these mechanisms at cellular and molecular terms and discuss their potential implications for promoting axon regeneration and functional recovery after nerve injury. PMID:27151637

  14. Quasar redshifts: the intrinsic component

    NASA Astrophysics Data System (ADS)

    Hansen, Peter M.

    2016-09-01

    The large observed redshift of quasars has suggested large cosmological distances and a corresponding enormous energy output to explain the brightness or luminosity as seen at earth. Alternative or complementary sources of redshift have not been identified by the astronomical community. This study examines one possible source of additional redshift: an intrinsic component based on the plasma characteristics of high temperature and high electron density which are believed to be present.

  15. Decoherence: Intrinsic, Extrinsic, and Environmental

    NASA Astrophysics Data System (ADS)

    Stamp, Philip

    2012-02-01

    Environmental decoherence times have been difficult to predict in solid-state systems. In spin systems, environmental decoherence is predicted to arise from nuclear spins, spin-phonon interactions, and long-range dipolar interactions [1]. Recent experiments have confirmed these predictions quantitatively in crystals of Fe8 molecules [2]. Coherent spin dynamics was observed over macroscopic volumes, with a decoherence Q-factor Qφ= 1.5 x10^6 (the upper predicted limit in this system being Qφ= 6 x10^7). Decoherence from dipolar interactions is particularly complex, and depends on the shape and the quantum state of the system. No extrinsic ``noise'' decoherence was observed. The generalization to quantum dot and superconducting qubit systems is also discussed. We then discuss searches for ``intrinsic'' decoherence [3,4], coming from non-linear corrections to quantum mechanics. Particular attention is paid to condensed matter tests of such intrinsic decoherence, in hybrid spin/optomechanical systems, and to ways of distinguishing intrinsic decoherence from environmental and extrinsic decoherence sources. [4pt] [1] Morello, A. Stamp, P. C. E. & Tupitsyn, Phys. Rev. Lett. 97, 207206 (2006).[0pt] [2] S. Takahashi et al., Nature 476, 76 (2011).[0pt] [3] Stamp, P. C. E., Stud. Hist. Phil. Mod. Phys. 37, 467 (2006). [0pt] [4] Stamp, P.C.E., Phil. Trans. Roy. Soc. A (to be published)

  16. Troponins, intrinsic disorder, and cardiomyopathy.

    PubMed

    Na, Insung; Kong, Min J; Straight, Shelby; Pinto, Jose R; Uversky, Vladimir N

    2016-08-01

    Cardiac troponin is a dynamic complex of troponin C, troponin I, and troponin T (TnC, TnI, and TnT, respectively) found in the myocyte thin filament where it plays an essential role in cardiac muscle contraction. Mutations in troponin subunits are found in inherited cardiomyopathies, such as hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). The highly dynamic nature of human cardiac troponin and presence of numerous flexible linkers in its subunits suggest that understanding of structural and functional properties of this important complex can benefit from the consideration of the protein intrinsic disorder phenomenon. We show here that mutations causing decrease in the disorder score in TnI and TnT are significantly more abundant in HCM and DCM than mutations leading to the increase in the disorder score. Identification and annotation of intrinsically disordered regions in each of the troponin subunits conducted in this study can help in better understanding of the roles of intrinsic disorder in regulation of interactomes and posttranslational modifications of these proteins. These observations suggest that disease-causing mutations leading to a decrease in the local flexibility of troponins can trigger a whole plethora of functional changes in the heart. PMID:27074551

  17. Localization of intrinsic factor and complement fixing intrinsic factor–intrinsic factor antibody complex in parietal cell of man

    PubMed Central

    Jacob, Elizabeth; Glass, G. B. J.

    1971-01-01

    In an attempt to localize intrinsic factor in the human parietal cell, and to study its intracellular union with the intrinsic factor antibody and complement, intrinsic factor antibody was separated from coexisting parietal cell antibody in pernicious anaemia sera by gel filtration. Intrinsic factor antibody of both `binding' and `blocking' type was also produced in rabbits by immunization with semi-purified human intrinsic factor–[57Co]B12 complex. Intrinsic factor antibody obtained from both sources produced fluorescence in the human parietal cells in the indirect Coons' test in the presence of fluoresceinated anti-human IgG. The fluorescence was localized peripherally, at the cell membrane. When instead of the fluoresceinated anti-human IgG a fluoresceinated anti-human complement (C) serum and normal complement containing serum were used, intrinsic factor antibody from both sources produced fluorescence of the entire parietal cell cytoplasm of the human mucosa. Thus, intrinsic factor was localized at highest concentration at the membrane of the parietal cell in man, the intrinsic factor antibody–intrinsic factor complex was demonstrated within the human parietal cell, and evidence was obtained that this antigen–antibody complex fixes complement (C). The possible role of the intrinsic factor–intrinsic factor antibody–complement complex in the development of gastric atrophy in pernicious anaemia has been considered. ImagesFIG. 3FIG. 4FIG. 5 PMID:4995933

  18. Detection of hypoxic cells with the 2-nitroimidazole, EF5, correlates with early redox changes in rat brain after perinatal hypoxia-ischemia.

    PubMed

    Bergeron, M; Evans, S M; Sharp, F R; Koch, C J; Lord, E M; Ferriero, D M

    1999-01-01

    hemisphere ipsilateral to the carotid occlusion, with a pattern similar to that reported previously for the histological damage seen in this model. This study provides a sensitive method for the evaluation of the level of oxygen depletion in brain tissue after neonatal hypoxia-ischemia at times much earlier than any method demonstrates apoptotic or necrotic cell death Since the level of in vivo formation of macromolecular adducts of EF5 depends on the degree of oxygen depletion in a tissue, intracellular EF5 binding may serve as a useful marker of regional cellular vulnerability and redox state after brain injury resulting from hypoxia-ischemia. PMID:10362320

  19. Regulation and clinical significance of the hypoxia-induced expression of ANGPTL4 in gastric cancer

    PubMed Central

    KUBO, HIROSHI; KITAJIMA, YOSHIHIKO; KAI, KEITA; NAKAMURA, JUN; MIYAKE, SHUUSUKE; YANAGIHARA, KAZUYOSHI; MORITO, KIYOTO; TANAKA, TOMOKAZU; SHIDA, MASAAKI; NOSHIRO, HIROKAZU

    2016-01-01

    Solid tumors are often exposed to hypoxia. Hypoxia inducible factor (HIF)-1α upregulates numerous target genes associated with the malignant behavior of hypoxic cancer cells. A member of the angiopoietin family, angiopoietin-like protein 4 (ANGPTL4) is a hypoxia-inducible gene. The present study aimed to clarify whether ANGPTL4 is regulated by HIF-1α in gastric cancer cells. The study also assessed whether ANGPTL4 expression is associated with clinicopathological factors or HIF-1α expression in gastric cancer tissues. Hypoxia-induced ANGPTL4 expression was quantitatively analyzed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in 10 gastric cancer cell lines. RT-qPCR was further employed to investigate the HIF-1α dependency of ANGPTL4 expression using HIF-1α-knockdown transfectant 58As9-KD and control 58As9-SC gastric cancer cells. The HIF-1α and ANGPTL4 expression levels were immunohistochemically analyzed in 170 gastric cancer tissue specimens and were assessed for any correlations with the clinicopathological factors and/or patient survival. Subsequently, hypoxia-induced ANGPTL4 expression was observed in 7 out of 10 gastric cancer cell lines. The hypoxic induction of ANGPTL4 was almost preserved in the 58As9-KD cells compared with that observed in the 58As9-SC cells, while the induction of known HIF-1α target gene, carbonic anhydrase 9, was completely suppressed in the 58As9-KD cells. In the gastric cancer tissues, ANGPTL4 expression was inversely correlated with the tumor depth, whereas HIF-1α expression was positively correlated with venous invasion. A survival analysis revealed that the expression of ANGPTL4 was significantly correlated with a longer survival time, whereas that of HIF-1α was correlated with a shorter survival time. In conclusion, the present findings indicate that hypoxia-induced ANGPTL4 expression is independent of HIF-1α in hypoxic gastric cancer cells. ANGPTL4 may be a favorable marker for predicting

  20. Cycling hypoxia: A key feature of the tumor microenvironment.

    PubMed

    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. PMID:27343712

  1. Prognostic Cell Biological Markers in Cervical Cancer Patients Primarily Treated With (Chemo)radiation: A Systematic Review

    SciTech Connect

    Noordhuis, Maartje G.; Eijsink, Jasper J.H.; Roossink, Frank; Graeff, Pauline de; Pras, Elisabeth; Schuuring, Ed; Wisman, G. Bea A.; Bock, Geertruida H. de; Zee, Ate G.J. van der

    2011-02-01

    The aim of this study was to systematically review the prognostic and predictive significance of cell biological markers in cervical cancer patients primarily treated with (chemo)radiation. A PubMed, Embase, and Cochrane literature search was performed. Studies describing a relation between a cell biological marker and survival in {>=}50 cervical cancer patients primarily treated with (chemo)radiation were selected. Study quality was assessed, and studies with a quality score of 4 or lower were excluded. Cell biological markers were clustered on biological function, and the prognostic and predictive significance of these markers was described. In total, 42 studies concerning 82 cell biological markers were included in this systematic review. In addition to cyclooxygenase-2 (COX-2) and serum squamous cell carcinoma antigen (SCC-ag) levels, markers associated with poor prognosis were involved in epidermal growth factor receptor (EGFR) signaling (EGFR and C-erbB-2) and in angiogenesis and hypoxia (carbonic anhydrase 9 and hypoxia-inducible factor-1{alpha}). Epidermal growth factor receptor and C-erbB-2 were also associated with poor response to (chemo)radiation. In conclusion, EGFR signaling is associated with poor prognosis and response to therapy in cervical cancer patients primarily treated with (chemo)radiation, whereas markers involved in angiogenesis and hypoxia, COX-2, and serum SCC-ag levels are associated with a poor prognosis. Therefore, targeting these pathways in combination with chemoradiation may improve survival in advanced-stage cervical cancer patients.

  2. Severe hypoxia exerts parallel and cell-specific regulation of gene expression and alternative splicing in human mesenchymal stem cells

    PubMed Central

    2014-01-01

    Background The endosteum of the bone marrow provides a specialized hypoxic niche that may serve to preserve the integrity, pluripotency, longevity and stemness of resident mesenchymal stem cells (MSCs). To explore the molecular genetic consequences of such a niche we subjected human (h) MSCs to a pO2 of 4 mmHg and analyzed global gene expression and alternative splicing (AS) by genome-exon microarray and RT-qPCR, and phenotype by western blot and immunostaining. Results Out of 446 genes differentially regulated by >2.5-fold, down-regulated genes outnumbered up-regulated genes by 243:203. Exon analyses revealed 60 hypoxia-regulated AS events with splice indices (SI) >1.0 from 53 genes and a correlation between high SI and degree of transcript regulation. Parallel analyses of a publicly available AS study on human umbilical vein endothelial cells (HUVECs) showed that there was a strong cell-specific component with only 11 genes commonly regulated in hMSCs and HUVECs and 17 common differentially spliced genes. Only 3 genes were differentially responsive to hypoxia at the gene (>2.0) and AS levels in both cell types. Functional assignments revealed unique profiles of gene expression with complex regulation of differentiation, extracellular matrix, intermediate filament and metabolic marker genes. Antioxidant genes, striated muscle genes and insulin/IGF-1 signaling intermediates were down-regulated. There was a coordinate induction of 9 out of 12 acidic keratins that along with other epithelial and cell adhesion markers implies a partial mesenchymal to epithelial transition. Conclusions We conclude that severe hypoxia confers a quiescent phenotype in hMSCs that is reflected by both the transcriptome profile and gene-specific changes of splicosome actions. The results reveal that severe hypoxia imposes markedly different patterns of gene regulation of MSCs compared with more moderate hypoxia. This is the first study to report hypoxia-regulation of AS in stem

  3. Neutrophil Gelatinase-Associated Lipocalin: Its Response to Hypoxia and Association with Acute Mountain Sickness

    PubMed Central

    Boos, Christopher; Stacey, Mike; Hooper, Tim; Smith, Chris; Yarker, Jo; Piper, Rick; O'Hara, John; King, Rod; Turner, Steve; Woods, David R.

    2013-01-01

    Acute Mountain Sickness (AMS) is a common clinical challenge at high altitude (HA). A point-of-care biochemical marker for AMS could have widespread utility. Neutrophil gelatinase-associated lipocalin (NGAL) rises in response to renal injury, inflammation and oxidative stress. We investigated whether NGAL rises with HA and if this rise was related to AMS, hypoxia or exercise. NGAL was assayed in a cohort (n = 22) undertaking 6 hours exercise at near sea-level (SL); a cohort (n = 14) during 3 hours of normobaric hypoxia (FiO2 11.6%) and on two trekking expeditions (n = 52) to over 5000 m. NGAL did not change with exercise at SL or following normobaric hypoxia. During the trekking expeditions NGAL levels (ng/ml, mean ± sd, range) rose significantly (P < 0.001) from 68 ± 14 (60–102) at 1300 m to 183 ± 107 (65–519); 143 ± 66 (60–315) and 150 ± 71 (60–357) at 3400 m, 4270 m and 5150 m respectively. At 5150 m there was a significant difference in NGAL between those with severe AMS (n = 7), mild AMS (n = 16) or no AMS (n = 23): 201 ± 34 versus 171 ± 19 versus 124 ± 12 respectively (P = 0.009 for severe versus no AMS; P = 0.026 for mild versus no AMS). In summary, NGAL rises in response to prolonged hypobaric hypoxia and demonstrates a relationship to the presence and severity of AMS. PMID:24227892

  4. Acetaminophen hepatotoxicity and HIF-1{alpha} induction in acetaminophen toxicity in mice occurs without hypoxia

    SciTech Connect

    Chaudhuri, Shubhra; McCullough, Sandra S.; Hennings, Leah; Letzig, Lynda; Simpson, Pippa M.; Hinson, Jack A.; James, Laura P.

    2011-05-01

    HIF-1{alpha} is a nuclear factor important in the transcription of genes controlling angiogenesis including vascular endothelial growth factor (VEGF). Both hypoxia and oxidative stress are known mechanisms for the induction of HIF-1{alpha}. Oxidative stress and mitochondrial permeability transition (MPT) are mechanistically important in acetaminophen (APAP) toxicity in the mouse. MPT may occur as a result of oxidative stress and leads to a large increase in oxidative stress. We previously reported the induction of HIF-1{alpha} in mice with APAP toxicity and have shown that VEGF is important in hepatocyte regeneration following APAP toxicity. The following study was performed to examine the relative contribution of hypoxia versus oxidative stress to the induction of HIF-1{alpha} in APAP toxicity in the mouse. Time course studies using the hypoxia marker pimonidazole showed no staining for pimonidazole at 1 or 2 h in B6C3F1 mice treated with APAP. Staining for pimonidazole was present in the midzonal to periportal regions at 4, 8, 24 and 48 h and no staining was observed in centrilobular hepatocytes, the sites of the toxicity. Subsequent studies with the MPT inhibitor cyclosporine A showed that cyclosporine A (CYC; 10 mg/kg) reduced HIF-1{alpha} induction in APAP treated mice at 1 and 4 h and did not inhibit the metabolism of APAP (depletion of hepatic non-protein sulfhydryls and hepatic protein adduct levels). The data suggest that HIF-1{alpha} induction in the early stages of APAP toxicity is secondary to oxidative stress via a mechanism involving MPT. In addition, APAP toxicity is not mediated by a hypoxia mechanism.

  5. Hypoxia reduces the effect of photoreceptor bleaching.

    PubMed

    Lin, Yun-Bin; Liu, Jorn-Hon; Chang, Yin

    2012-07-01

    Hypoxia and light illumination can both decrease oxygen consumption in the photoreceptor layers. The purpose of the present study was to investigate whether the mutual effects of hypoxia and intense illumination to the photoreceptors are additive. The a-wave of flash electroretinogram (fERG) was recorded to indirectly measure the photoreceptors function under given conditions. Six normal healthy subjects, mean age 34.0 ± 3.8 years, all of whom had high-altitude (>3,000 m) mountain hiking experience, were recruited for the study. Flash a-wave electroretinography was examined under four conditions: (1) normal (D/N); (2) systemic hypoxia induced by inhaling a mixture of O(2) and N(2) gases, which caused oxyhemoglobin saturation (SaO(2)) ≈ 80% (D/H); (3) intense light illumination, which resulted in photoreceptor bleaching (B/N); and (4) a combination of conditions b and c (B/H). Thirty light stimuli, each with a 20-ms ON and 1,980-ms OFF cycle, were given and ERG performed to probe the photoreceptor function. The results showed that a-wave at the various conditions did not respond to all stimuli. The average a-wave amplitudes were 91.4 ± 46.5, 22.8 ± 42.5, 15.5 ± 28.9, and 35.2 ± 41.1 μV for D/N, D/H, B/N, and B/H, respectively. Nonparametric Friedman test for a-wave amplitude indicated that significant differences occurred in D/N-D/H, D/N-B/N, D/N-B/H, D/H-B/H, and B/N-B/H (all p values were <0.001, but D/H-B/N was 0.264). Thus, systemic hypoxia or strong illumination to the retina can cause an absence of the ERG a-wave or change its response, although individual differences were observed. In this study, systemic hypoxia appeared to reduce photoreceptor bleaching, an interesting finding in itself. The mechanisms underlying the disappearance of the ERG a-wave following hypoxia or intense illumination to the photoreceptors seem to differ. PMID:22544448

  6. Targeting Hypoxia-Inducible Factor 1α in a New Orthotopic Model of Glioblastoma Recapitulating the Hypoxic Tumor Microenvironment.

    PubMed

    Nigim, Fares; Cavanaugh, Jill; Patel, Anoop P; Curry, William T; Esaki, Shin-ichi; Kasper, Ekkehard M; Chi, Andrew S; Louis, David N; Martuza, Robert L; Rabkin, Samuel D; Wakimoto, Hiroaki

    2015-07-01

    Tissue hypoxia and necrosis represent pathophysiologic and histologic hallmarks of glioblastoma (GBM). Although hypoxia inducible factor 1α (HIF-1α) plays crucial roles in the malignant phenotypes of GBM, developing HIF-1α-targeted agents has been hampered by the lack of a suitable preclinical model that recapitulates the complex biology of clinical GBM. We present a new GBM model, MGG123, which was established from a recurrent human GBM. Orthotopic xenografting of stem-like MGG123 cells reproducibly generated lethal tumors that were characterized by foci of palisading necrosis, hypervascularity, and robust stem cell marker expression. Perinecrotic neoplastic cells distinctively express HIF-1α and are proliferative in both xenografts and the patient tissue. The xenografts contain scattered hypoxic foci that were consistently greater than 50 μm distant from blood vessels, indicating intratumoral heterogeneity of oxygenation. Hypoxia enhanced HIF-1α expression in cultured MGG123 cells, which was abrogated by the HIF-1α inhibitors digoxin or ouabain. In vivo, treatment of orthotopic MGG123 xenografts with digoxin decreased HIF-1α expression, vascular endothelial growth factor mRNA levels, and CD34-positive vasculature within the tumors, and extended survival of mice bearing the aggressive MGG123 GBM. This preclinical tumor model faithfully recapitulates the GBM-relevant hypoxic microenvironment and stemness and is a suitable platform for studying disease biology and developing hypoxia-targeted agents. PMID:26083570

  7. Targeting Hypoxia-inducible Factor 1α in a New Orthotopic Model of Glioblastoma Recapitulating the Hypoxic Tumor Microenvironment

    PubMed Central

    Nigim, Fares; Cavanaugh, Jill; Patel, Anoop P.; Curry, William T.; Esaki, Shin-ichi; Kasper, Ekkehard M.; Chi, Andrew S.; Louis, David N.; Martuza, Robert L.; Rabkin, Samuel D.; Wakimoto, Hiroaki

    2015-01-01

    Tissue hypoxia and necrosis represent pathophysiological and histological hallmarks of glioblastoma (GBM). Although hypoxia inducible factor 1α (HIF-1α) plays crucial roles in the malignant phenotypes of GBM, developing HIF-1α-targeted agents has been hampered by the lack of a suitable preclinical model that recapitulates the complex biology of clinical GBM. We present a new GBM model, MGG123, which was established from a recurrent human GBM. Orthotopic xenografting of stem-like MGG123 cells reproducibly generated lethal tumors that were characterized by foci of palisading necrosis, hypervascularity, and robust stem cell marker expression. Perinecrotic neoplastic cells distinctively express HIF-1α and are proliferative in both xenografts and the patient tissue. The xenografts contain scattered hypoxic foci that were consistently >50 μm distant from blood vessels, indicating intratumoral heterogeneity of oxygenation. Hypoxia enhanced HIF-1α expression in cultured MGG123 cells, which was abrogated by the HIF-1α inhibitors digoxin or ouabain. In vivo, treatment of orthotopic MGG123 xenografts with digoxin decreased HIF-1α expression, vascular endothelial growth factor mRNA levels and CD34-positive vasculature within the tumors, and extended survival of mice bearing the aggressive MGG123 GBM. This preclinical tumor model faithfully recapitulates the GBM-relevant hypoxic microenvironment and stemness, and is a suitable platform for studying disease biology and developing hypoxia-targeted agents. PMID:26083570

  8. Patterns and Levels of Hypoxia in Head and Neck Squamous Cell Carcinomas and Their Relationship to Patient Outcome

    SciTech Connect

    Evans, Sydney M. V. Du, Kevin L.; Chalian, Ara A.; Mick, Rosemarie; Zhang, Paul J.; Hahn, Stephen M.; Quon, Harry; Lustig, Robert; Weinstein, Gregory S.; Koch, Cameron J.

    2007-11-15

    Purpose: EF5, a 2-nitroimidazole hypoxia marker, was used to study the presence, levels, and prognostic significance of hypoxia in primary head and neck squamous cell tumors. Methods and Materials: Twenty-two patients with newly diagnosed squamous cell carcinoma of the oral cavity, oropharynx, or larynx with at least 2 years of clinical follow-up were included in this study. Quantitative analyses of EF5 immunofluorescence was carried out, and these data were compared with patient outcome. Results: EF5 immunostaining showed substantial intra- and intertumoral hypoxic heterogeneity. The majority of cells in all tumors were well oxygenated. Three patterns of EF5 binding in cells were identified using criteria based on the cellular region that was stained (peripheral or central) and the relationship of binding to necrosis. We tested the association between EF5-binding levels with event-free and overall survival irrespective of the pattern of cellular binding or treatment regimen. Patients with tumors containing EF5-binding regions corresponding to severe hypoxia ({<=}0.1% oxygen) had a shorter event-free survival time than patients with pO{sub 2} values greater than 0.1% (p = 0.032). Nodal status was also predictive for outcome. Conclusions: These data illustrate the potential utility of EF5 binding based on quantitative immunohistochemistry of tissue pO{sub 2} and provide support for the development of noninvasive hypoxia positron emission tomographic studies with fluorine 18-labeled EF5.

  9. Intrinsic and Synthetic Stable Isotope Marking of Tsetse Flies

    PubMed Central

    Hood-Nowotny, Rebecca; Watzka, Margarete; Mayr, Leo; Mekonnen, Solomon; Kapitano, Berisha; Parker, Andrew

    2011-01-01

    The sterile insect technique has been successfully used to eliminate tsetse populations in a number of programs. Program monitoring in the field relies on the ability to accurately differentiate released sterile insects from wild insects so that estimates can be made of the ratio of sterile males to wild males. Typically, released flies are marked with a dye, which is not always reliable. The difference in isotopic signatures between wild and factory-reared populations could be a reliable and intrinsic secondary marker to complement existing marking methods. Isotopic signatures are natural differences in stable isotope composition of organisms due to discrimination against the heavier isotopes during some biological processes. As the isotopic signature of an organism is mainly dependent on what it eats; by feeding factory-reared flies isotopically different diets to those of the wild population it is possible to intrinsically mark the flies. To test this approach unlabeled samples of Glossina pallidipes (Austen) (Diptera: Glossinidae) from a mass rearing facility and wild populations were analyzed to determine whether there were any natural differences in signatures that could be used as markers. In addition experiments were conducted in which the blood diet was supplemented with isotopically enriched compounds and the persistence of the marker in the offspring determined. There were distinct natural isotopic differences between factory reared and wild tsetse populations that could be reliably used as population markers. It was also possible to rear artificially isotopically labeled flies using simple technology and these flies were clearly distinguishable from wild populations with greater than 95% certainty after 85 days of “release”. These techniques could be readily adopted for use in SIT programs as complimentary marking techniques. PMID:21870965

  10. Intrinsic and synthetic stable isotope marking of tsetse flies.

    PubMed

    Hood-Nowotny, Rebecca; Watzka, Margarete; Mayr, Leo; Mekonnen, Solomon; Kapitano, Berisha; Parker, Andrew

    2011-01-01

    The sterile insect technique has been successfully used to eliminate tsetse populations in a number of programs. Program monitoring in the field relies on the ability to accurately differentiate released sterile insects from wild insects so that estimates can be made of the ratio of sterile males to wild males. Typically, released flies are marked with a dye, which is not always reliable. The difference in isotopic signatures between wild and factory-reared populations could be a reliable and intrinsic secondary marker to complement existing marking methods. Isotopic signatures are natural differences in stable isotope composition of organisms due to discrimination against the heavier isotopes during some biological processes. As the isotopic signature of an organism is mainly dependent on what it eats; by feeding factory-reared flies isotopically different diets to those of the wild population it is possible to intrinsically mark the flies. To test this approach unlabeled samples of Glossina pallidipes (Austen) (Diptera: Glossinidae) from a mass rearing facility and wild populations were analyzed to determine whether there were any natural differences in signatures that could be used as markers. In addition experiments were conducted in which the blood diet was supplemented with isotopically enriched compounds and the persistence of the marker in the offspring determined. There were distinct natural isotopic differences between factory reared and wild tsetse populations that could be reliably used as population markers. It was also possible to rear artificially isotopically labeled flies using simple technology and these flies were clearly distinguishable from wild populations with greater than 95% certainty after 85 days of "release". These techniques could be readily adopted for use in SIT programs as complimentary marking techniques. PMID:21870965

  11. Hypoxia-inducible factors 1 and 2 are important transcriptional effectors in primary macrophages experiencing hypoxia.

    PubMed

    Fang, Hsin-Yu; Hughes, Russell; Murdoch, Craig; Coffelt, Seth B; Biswas, Subhra K; Harris, Adrian L; Johnson, Randall S; Imityaz, Hongxia Z; Simon, M Celeste; Fredlund, Erik; Greten, Florian R; Rius, Jordi; Lewis, Claire E

    2009-07-23

    Ischemia exists in many diseased tissues, including arthritic joints, atherosclerotic plaques, and malignant tumors. Macrophages accumulate in these sites and up-regulate hypoxia-inducible transcription factors (HIFs) 1 and 2 in response to the hypoxia present. Here we show that the gene expression profile in primary human and murine macrophages changes markedly when they are exposed to hypoxia for 18 hours. For example, they were seen to up-regulate the cell surface receptors, CXCR4 and GLUT1, and the potent, tumor-promoting cytokines, vascular endothelial growth factor A, interleukin (IL)-1beta and IL-8, adrenomedullin, CXCR4, and angiopoietin-2. Hypoxia also stimulated their expression and/or phosphorylation of various proteins in the nuclear factor-kappaB (NF-kappaB) signaling pathway. We then used both genetic and pharmacologic methods to manipulate the levels of HIFs-1alpha and 2alpha or NF-kappaB in primary macrophages to elucidate their role in the hypoxic induction of many of these key genes. These studies showed that both HIF-1 and -2, but not NF-kappaB, are important transcriptional effectors regulating the responses of macrophages to such a period of hypoxia. Further studies using experimental mouse models are now warranted to investigate the role of such macrophage responses in the progression of various diseased tissues, such as malignant tumors. PMID:19454749

  12. Hypoxia inducible factors 1 and 2 are important transcriptional effectors in primary macrophages experiencing hypoxia

    PubMed Central

    Fang, Hsin-Yu; Hughes, Russell; Murdoch, Craig; Coffelt, Seth; Biswas, Subhra K.; Harris, Adrian L.; Johnson, Randall S.; Imityaz, Hongxia Z.; Simon, M. Celeste; Fredlund, Erik; Greten, Florian; Rius, Jordi; Lewis, Claire E.

    2010-01-01

    Ischemia exists in many diseased tissues including arthritic joints, atherosclerotic plaques and malignant tumors. Macrophages accumulate in these sites and upregulate hypoxia-inducible transcription factors (HIFs) 1 and 2 in response to the hypoxia present. Here we show that the gene expression profile in primary human and murine macrophages changes markedly when they are exposed to hypoxia for 18h. For example, they were seen to upregulate the cell surface receptors, CXCR4 and GLUT1, and the potent, tumor-promoting cytokines, VEGFA, interleukins 1β and 8, adrenomedullin, CXCR4 and angiopoietin-2. Hypoxia also stimulated their expression and/or phosphorylation of various proteins in the NF-κB signalling pathway. We then used both genetic and pharmacological methods to manipulate the levels of HIFs 1α and 2α or NF-κB in primary macrophages in order to elucidate their role in the hypoxic induction of many of these key genes. These studies showed that both HIFs 1 and 2, but not NF-κB, are important transcriptional effectors regulating the responses of macrophages to such a period of hypoxia. Further studies using experimental mouse models are now warranted to investigate the role of such macrophage responses in the progression of various diseased tissues like malignant tumors. PMID:19454749

  13. Intraday Variability: Intrinsic or Extrinsic?

    NASA Astrophysics Data System (ADS)

    Sarma Kuchibhotla, Huthavahana; Lister, Matthew; Homan, Dan; Kellermann, Ken; Aller, Hugh; Aller, Margo; Agudo, Ivan; Arshakian, Tigran; Kovalev, Yuri; Lobanov, Andrew; Pushkarev, Alexander; Ros, Eduardo; Savolainen, Tuomas; Zensus, Tony; Kadler, Matthias; Vermeulen, Rene; Gehrels, Neil; McEnery, Julie; Sambruna, Rita; Tueller, Jack; Cohen, Marshall; Hovatta, Talvikki; Kharb, Preeti; Cooper, Nathan; Hogan, Brandon; Cara, Mihai

    A significant fraction of flat spectrum AGN exhibit rapid variability both in total intensity as well as polarization at cm wavelengths, on time scales ranging from a few hours to a few days, a phenomenon termed Intra Day Variability (IDV). The physical process responsible for this behavior is not well understood, though various models ranging from source-intrinsic (e.g., shock-in-jet) to source-extrinsic (e.g., scintillation due to electron density fl uctuations in the interstellar medium) have been proposed. The absence of multi-epoch data (especially at 2 cm) further exacerbates the situation. We present the results of analysis of archival VLBA data for a flux density limited sample of bright, flat spectrum AGN located predominantly in the north-ern sky, collected under the MOJAVE program. We find a clear detection of IDV in 25% of the 365 sources analyzed. We find significant differences in the IDV properties of quasars and true BL Lacs. Intermediate BL Lac objects, so classified due to the presence of broad lines in their optical spectra, have IDV characteristics similar to those of quasars. As expected, the presum-able weakly beamed CSS/GPS sources show no IDV. We find IDV properties to be correlated with source intrinsic properties such as Brightness temperature/Doppler factor and apparent speed. Episodes of IDV activity associated with radio flaring and/or component ejection have also been observed, suggesting an intrinsic mechanism at work. However, we also find IDV to be strongly correlated with the galactic latitude position of the source, indicative of a scintil-lation mechanism. However, we find no correlation between IDV and the observing day of the year, IDV and redshift of the source. We propose a qualitative model to explain all these results. The program is supported under the NSF grant 080786-AST and NASA grant NNX08AV67G.

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

    PubMed

    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

  15. Pair breaking and ``intrinsic`` {Tc}

    SciTech Connect

    Wolf, S.A.; Kresin, V.Z.; Ovchinnikov, Y.N.

    1996-12-31

    An analysis of the temperature dependence of the upper critical field in several cuprate families leads to the conclusion that magnetic impurities are present even in samples with the maximum observed value of T{sub c}. A new parameter, intrinsic T{sub c} (T{sub c;intr}) which is its value in the absence of magnetic impurities, is introduced. The maximum value of T{sub c;intr}, which corresponds to the maximum doping level, appears to be similar for different cuprates and to be equal to 160--170 K. This is an upper limit of T{sub c} in the cuprates.

  16. Nuclear Filtering of Intrinsic Charm

    SciTech Connect

    Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan

    2010-11-12

    Nuclei are transparent for a heavy intrinsic charm (IC) component of the beam hadrons, what leads to an enhanced nuclear dependence of open charm production at large Feynman x{sub F}. Indeed, such an effect is supported by data from the SELEX experiment published recently [1]. Our calculations reproduce well the data, providing strong support for the presence of IC in hadrons in amount less than 1%. Moreover, we performed an analysis of nuclear effects in J/{Psi} production and found at large x{sub F} a similar, albeit weaker effect, which does not contradict data.

  17. Optical Investigations of Physiology: A Study of Intrinsic and Extrinsic Biomedical Contrast

    NASA Astrophysics Data System (ADS)

    Chance, Britton; Luo, Qingming; Nioka, Shoko; Alsop, David C.; Detre, John A.

    1997-06-01

    The utility and performance of optical studies of tissue depends upon the contrast and the changes of contrast in health and disease and in functional activity. The contrast is determined both by the optical properties of extrinsic and intrinsic chromophores and scatterers but especially upon the changes evoked by physiological activity and pathological states. Here, we have focused upon absorption changes of the intrinsic probe, blood absorbance changes due to cortical hypoxia and to haematomas, giving, for particular conditions, absorbance changes of 0.15 and over 0.4 Δ OD, respectively. Functional activity may give changes of blood volume of over 0.05 Δ OD with some variability due to individual responses that is best expressed as histogram displays of the distribution of response among a significant population. Responses have been observed in prefrontal parietal and occipital functions (242 tests). Extrinsic probes afford signals dependent upon the dose tolerance of the subject and can readily equal or exceed the blood volume and oxygenation signals, and currently afford vascular volume and flow indications. However, contrast agents for the functional activity of cellular function are ultimately to be expected. Finally, light-scattering changes afford osmolyte-related responses and are here shown to indicate a large signal attributed to cortical depolarization and K+ release in hypoxia/ischaemia. Thus, the optical method affords imaging of manifold contrasts that greatly enhance its specificity and sensitivity for diagnostic procedures.

  18. Psychomotor skills learning under chronic hypoxia.

    PubMed

    Bouquet, C A; Gardette, B; Gortan, C; Abraini, J H

    1999-09-29

    Psychomotor deficits are a prominent feature in subjects exposed to hypoxia. Eight subjects exposed to chronic hypoxia during a simulated climb to 8848 m (Everest-Comex 97) were investigated using both a simple psychomotor task (Purdue pegboard) and two complex psychomotor tasks including a recognition task of either a color stimulus (high semantic level) or an abstract sign (low semantic level). Exposure to hypoxic stress mainly produced psychomotor skills learning deficits compared to control study, with greater deficits in the complex psychomotor task. The pattern of results suggests disruptions of motor strategic process. Our data further suggest that the relative strength of implicit or automatic memory processes associated with semantic information processing may increase when disturbances occur in brain functions. PMID:10549829

  19. Electrophysiological properties of laryngeal motoneurones in rats submitted to chronic intermittent hypoxia

    PubMed Central

    Moraes, Davi J A; Machado, Benedito H

    2015-01-01

    To keep an appropriate airflow to and from the lungs under physiological conditions a precise neural co-ordination of the upper airway resistance by laryngeal motoneurones in the nucleus ambiguus is essential. Chronic intermittent hypoxia (CIH), an important component of obstructive sleep apnoea, may alter these fine mechanisms. Here, using nerve and whole cell patch clamp recordings in in situ preparations of rats we investigated the effects of CIH on the respiratory control of the upper airway resistance, on the electrophysiological properties of laryngeal motoneurones in the nucleus ambiguus, and the role of carotid body (CB) afferents to the brainstem on the underlying mechanisms of these effects. CIH rats exhibited longer pre-inspiratory and lower post-inspiratory superior laryngeal nerve activities than control rats. These changes produced exaggerated glottal abduction (before inspiration) and decreased glottal adduction during post-inspiration, indicating a reduction of upper airway resistance during these respiratory phases after CIH. CB denervation abolished these changes produced by CIH. Regarding choline acetyltransferase positive-laryngeal motoneurones, CIH increased the firing frequency of inspiratory and decreased the firing frequency of post-inspiratory laryngeal motoneurones, without changes in their intrinsic electrophysiological properties. These data show that the effects of CIH on the upper airway resistance and laryngeal motoneurones activities are driven by the integrity of CB, which afferents induce changes in the central respiratory generators in the brainstem. These neural changes in the respiratory network seem to be an adaptive process required for an appropriated pulmonary ventilation and control of upper airway resistance under intermittent episodes of hypoxia. Key points The respiratory control of the glottis by laryngeal motoneurones is characterized by inspiratory abduction and post-inspiratory adduction causing decreases and

  20. Regulation of cell proliferation by hypoxia-inducible factors.

    PubMed

    Hubbi, Maimon E; Semenza, Gregg L

    2015-12-15

    Hypoxia is a physiological cue that impacts diverse physiological processes, including energy metabolism, autophagy, cell motility, angiogenesis, and erythropoiesis. One of the key cell-autonomous effects of hypoxia is as a modulator of cell proliferation. For most cell types, hypoxia induces decreased cell proliferation, since an increased number of cells, with a consequent increase in O2 demand, would only exacerbate hypoxic stress. However, certain cell populations maintain cell proliferation in the face of hypoxia. This is a common pathological hallmark of cancers, but can also serve a physiological function, as in the maintenance of stem cell populations that reside in a hypoxic niche. This review will discuss major molecular mechanisms by which hypoxia regulates cell proliferation in different cell populations, with a particular focus on the role of hypoxia-inducible factors. PMID:26491052

  1. Hypoxia Responsive Drug Delivery Systems in Tumor Therapy.

    PubMed

    Alimoradi, Houman; Matikonda, Siddharth S; Gamble, Allan B; Giles, Gregory I; Greish, Khaled

    2016-01-01

    Hypoxia is a common characteristic of solid tumors. It is mainly determined by low levels of oxygen resulting from imperfect vascular networks supplying most tumors. In an attempt to improve the present chemotherapeutic treatment and reduce associated side effects, several prodrug strategies have been introduced to achieve hypoxia-specific delivery of cytotoxic anticancer agents. With the advances in nanotechnology, novel delivery systems activated by the consequent outcomes of hypoxia have been developed. However, developing hypoxia responsive drug delivery systems (which only depend on low oxygen levels) is currently naïve. This review discusses four main hypoxia responsive delivery systems: polymeric based drug delivery systems, oxygen delivery systems combined with radiotherapy and chemotherapy, anaerobic bacteria which are used for delivery of genes to express anticancer proteins such as tumor necrosis alpha (TNF-α) and hypoxia-inducible transcription factors 1 alpha (HIF1α) responsive gene delivery systems. PMID:26898739

  2. Ceramic subsurface marker prototypes

    SciTech Connect

    Lukens, C.E.

    1985-05-02

    The client submitted 5 sets of porcelain and stoneware subsurface (radioactive site) marker prototypes (31 markers each set). The following were determined: compressive strength, thermal shock resistance, thermal crazing resistance, alkali resistance, color retention, and chemical resistance.

  3. Ischaemic Markers in Acute Hepatic Injury

    PubMed Central

    Jena, Sushanta Kumar; Nanda, Rachita; Mangaraj, Manaswini; Nayak, Parsuram

    2016-01-01

    Introduction Hepatic injury of varied aetiology may progress to Acute Liver Failure (ALF). Compromised microcirculation is thought to be a deciding factor of hepatic hypoxia may be involved in disease progression that needs early detection. Ischaemia markers like serum Ischaemia- modified albumin (IMA), ALT-LDH ratio and ALT-LDH index have been suggested for its detection at early stage. Aim To find out the association of Ischaemia markers like serum IMA, ALT-LDH ratio and ALT-LDH index in acute hepatic injury cases. Materials and Methods Forty one diagnosed acute liver injury cases of varied aetiology admitted in Department of Medicine, and Gastroenterology of SCB Medical College, Cuttack were enrolled in the study along with 30 age and sex matched healthy controls. Blood collected at time of admission and at time of discharge (1st day and 7th day) were evaluated for FPG, RFT, LFT, Serum Albumin along with serum LDH, IMA, PT-INR and platelet count. Result Serum bilirubin, hepatic enzymes, IMA, PT-INR was more markedly raised in cases than controls on the 1st day of admission. ALT-LDH ratio and index were significantly low in complicated cases. However, on responding to treatment the ALT-LDH index on 7th day registered a rise in comparison to the 1st day, while serum IMA revealed an insignificant decline showing improvement in hepatic hypoxia. ALT-LDH ratio remains more or less same on response to treatment. Conclusion Serum IMA and ALT-LDH Index reveals association with disease process in Acute Hepatic Injury cases both clinically and biochemically and can be used as supportive parameters for the diagnosis of disease process. PMID:27190791

  4. Pathophysiology and clinical effects of chronic hypoxia.

    PubMed

    Pierson, D J

    2000-01-01

    Hypoxia exists when there is a reduced amount of oxygen in the tissues of the body. Hypoxemia refers to a reduction in PO2 below the normal range, regardless of whether gas exchange is impaired in the lung, CaO2 is adequate, or tissue hypoxia exists. There are several potential physiologic mechanisms for hypoxemia, but in patients with COPD the predominant one is V/Q mismatching, with or without alveolar hypoventilation, as indicated by PaCO2. Hypoxemia caused by V/Q mismatching as seen in COPD is relatively easy to correct, so that only comparatively small amounts of supplemental oxygen (less than 3 L/min for the majority of patients) are required for LTOT. Although hypoxemia normally stimulates ventilation and produces dyspnea, these phenomena and the other symptoms and signs of hypoxia are sufficiently variable in patients with COPD as to be of limited value in patient assessment. Chronic alveolar hypoxia is the main factor leading to development of cor pulmonale--right ventricular hypertrophy with or without overt right ventricular failure--in patients with COPD. Pulmonary hypertension adversely affects survival in COPD, to an extent that parallels the degree to which resting mean pulmonary artery pressure is elevated. Although the severity of airflow obstruction as measured by FEV1 is the best correlate with overall prognosis in patients with COPD, chronic hypoxemia increases mortality and morbidity for any severity of disease. Large-scale studies of LTOT in patients with COPD have demonstrated a dose-response relationship between daily hours of oxygen use and survival. There is reason to believe that continuous, 24-hours-per-day oxygen use in appropriately selected patients would produce a survival benefit even greater than that shown in the NOTT and MRC studies. PMID:10771781

  5. Hypoxia and Dysregulated Angiogenesis in Kidney Disease

    PubMed Central

    Tanaka, Shinji; Tanaka, Tetsuhiro; Nangaku, Masaomi

    2015-01-01

    Background Accumulating evidence has demonstrated that renal hypoxia has a crucial role in the pathogenesis of acute kidney injury (AKI), chronic kidney disease (CKD), and AKI-to-CKD transition, ultimately culminating in end-stage kidney disease. Renal hypoxia in progressive CKD is intricately linked to persisting capillary loss, which is mainly due to dysregulated angiogenesis. Summary In CKD, hypoxia-inducible factor (HIF) accumulates in the ischemic tubulointerstitium but fails to sufficiently stimulate angiogenic responses, partly because of blunted activation of HIF, which is best exemplified in diabetic kidney disease. In addition, vascular endothelial growth factor (VEGF) expression is downregulated, possibly because injured tubules are not able to express sufficient VEGF and inflammatory circumstances inhibit VEGF expression. The upregulation of antiangiogenic factors and the incompetence of endothelial progenitor cells (EPCs) may also play some roles in the inadequacy of capillary restoration. Administration of VEGF or angiopoietin-1 maintains peritubular capillaries in several kidney diseases; however, administration of a single angiogenic factor may lead to the formation of abnormal vessels and induce inflammation, resulting in worsening of hypoxia and tubulointerstitial fibrosis. HIF stabilization, which aims to achieve the formation of mature and stable vessels by inducing coordinated angiogenesis, is a promising strategy. Given that the effect of systemic HIF activation is highly context-dependent, further studies are needed to elucidate the precise roles of HIF in various kidney diseases. The adoptive transfer of EPCs or mesenchymal stem cells (MSCs) is a fascinating alternative strategy to restore the peritubular capillaries. Key Message Suppressed HIF activation and VEGF expression may be responsible for the dysregulated angiogenesis in progressive CKD. Administration of a single angiogenic factor can cause abnormal vessel formation and

  6. NASA Gulf of Mexico Initiative Hypoxia Research

    NASA Technical Reports Server (NTRS)

    Armstrong, Curtis D.

    2012-01-01

    The Applied Science & Technology Project Office at Stennis Space Center (SSC) manages NASA's Gulf of Mexico Initiative (GOMI). Addressing short-term crises and long-term issues, GOMI participants seek to understand the environment using remote sensing, in-situ observations, laboratory analyses, field observations and computational models. New capabilities are transferred to end-users to help them make informed decisions. Some GOMI activities of interest to the hypoxia research community are highlighted.

  7. Humans In Hypoxia: A Conspiracy Of Maladaptation?!

    PubMed

    Dempsey, Jerome A; Morgan, Barbara J

    2015-07-01

    We address adaptive vs. maladaptive responses to hypoxemia in healthy humans and hypoxic-tolerant species during wakefulness, sleep, and exercise. Types of hypoxemia discussed include short-term and life-long residence at high altitudes, the intermittent hypoxemia attending sleep apnea, or training regimens prescribed for endurance athletes. We propose that hypoxia presents an insult to O2 transport, which is poorly tolerated in most humans because of the physiological cost. PMID:26136544

  8. Humans In Hypoxia: A Conspiracy Of Maladaptation?!

    PubMed Central

    Morgan, Barbara J.

    2015-01-01

    We address adaptive vs. maladaptive responses to hypoxemia in healthy humans and hypoxic-tolerant species during wakefulness, sleep, and exercise. Types of hypoxemia discussed include short-term and life-long residence at high altitudes, the intermittent hypoxemia attending sleep apnea, or training regimens prescribed for endurance athletes. We propose that hypoxia presents an insult to O2 transport, which is poorly tolerated in most humans because of the physiological cost. PMID:26136544

  9. Cell and Signal Components of the Microenvironment of Bone Metastasis Are Affected by Hypoxia

    PubMed Central

    Bendinelli, Paola; Maroni, Paola; Matteucci, Emanuela; Desiderio, Maria Alfonsina

    2016-01-01

    Bone metastatic cells release bone microenvironment proteins, such as the matricellular protein SPARC (secreted protein acidic and rich in cysteine), and share a cell signaling typical of the bone metabolism controlled by Runx2. The megakaryocytes in the bone marrow engrafted by the metastases seem to be one of the principal microenvironment sources of the biological stimuli, implicated in the formation of an osteoblastic niche, and affecting metastasis phenotype and colonization. Educated platelets in the circulation might derive from megakaryocytes in bone metastasis. The evaluation of predictive markers in the circulating platelets might be useful for the stratification of patients for therapeutic purposes. The hypoxic environment in bone metastasis is one of the key regulators of the network of the biological soluble and structural components of the matrix. In bone metastatic cells under hypoxia, similar patterns of Runx2 and SPARC are observed, both showing downregulation. Conversely, hypoxia induces Endothelin 1, which upregulates SPARC, and these biological stimuli may be considered prognostic markers of bone metastasis in breast carcinoma patients. PMID:27187355

  10. Cell and Signal Components of the Microenvironment of Bone Metastasis Are Affected by Hypoxia.

    PubMed

    Bendinelli, Paola; Maroni, Paola; Matteucci, Emanuela; Desiderio, Maria Alfonsina

    2016-01-01

    Bone metastatic cells release bone microenvironment proteins, such as the matricellular protein SPARC (secreted protein acidic and rich in cysteine), and share a cell signaling typical of the bone metabolism controlled by Runx2. The megakaryocytes in the bone marrow engrafted by the metastases seem to be one of the principal microenvironment sources of the biological stimuli, implicated in the formation of an osteoblastic niche, and affecting metastasis phenotype and colonization. Educated platelets in the circulation might derive from megakaryocytes in bone metastasis. The evaluation of predictive markers in the circulating platelets might be useful for the stratification of patients for therapeutic purposes. The hypoxic environment in bone metastasis is one of the key regulators of the network of the biological soluble and structural components of the matrix. In bone metastatic cells under hypoxia, similar patterns of Runx2 and SPARC are observed, both showing downregulation. Conversely, hypoxia induces Endothelin 1, which upregulates SPARC, and these biological stimuli may be considered prognostic markers of bone metastasis in breast carcinoma patients. PMID:27187355

  11. Hypoxia-Mediated Soluble Fms-Like Tyrosine Kinase 1 Increase Is Not Attenuated in Interleukin 6-Deficient Mice.

    PubMed

    Appel, Sarah; Turnwald, Eva-Maria; Ankerne, Janina; Wohlfarth, Maria; Appel, Jan; Rother, Eva; Janoschek, Ruth; Alejandre Alcazar, Miguel A; Schnare, Markus; Meißner, Udo; Dötsch, Jörg

    2015-06-01

    The soluble fms-like tyrosine kinase 1 (sFlt-1), known to be increased in the serum of preeclamptic patients, is a relevant factor in causing maternal symptoms like hypertension and proteinuria. In this study, we aimed to reveal whether hypoxia is a cause of increased sFlt-1 levels and inflammation markers in vivo and whether these symptoms can be attenuated by interleukin 6 (IL-6) depletion. For this purpose, pregnant wild-type (wt) mice or IL-6(-/-) mice on embryonic day 16 were placed under either normoxic (20.9% oxygen) or hypoxic (6% oxygen) conditions for 6 hours. This led to a rise of sFlt-1 levels in maternal serum, independent of the IL-6 status of the dam. Increased maternal sFlt-1 serum levels were, however, not due to an increase in sFlt-1 messenger RNA levels in the placenta. Moreover, there was no increase in inflammatory markers in neither wt mice nor IL-6(-/-) mice. This suggests that hypoxia alone does not contribute to the induction of an inflammatory placenta. Also, the hypoxia-induced rise in sFlt-1 levels seems not to be mediated by IL-6 in vivo. PMID:25415335

  12. Effects of hypoxia on sympathetic neural control in humans

    NASA Technical Reports Server (NTRS)

    Smith, M. L.; Muenter, N. K.

    2000-01-01

    This special issue is principally focused on the time domain of the adaptive mechanisms of ventilatory responses to short-term, long-term and intermittent hypoxia. The purpose of this review is to summarize the limited literature on the sympathetic neural responses to sustained or intermittent hypoxia in humans and attempt to discern the time domain of these responses and potential adaptive processes that are evoked during short and long-term exposures to hypoxia.

  13. Optical imaging of tumor hypoxia dynamics

    NASA Astrophysics Data System (ADS)

    Palmer, Gregory M.; Fontanella, Andrew N.; Zhang, Guoqing; Hanna, Gabi; Fraser, Cassandra L.; Dewhirst, Mark W.

    2010-11-01

    The influence of the tumor microenvironment and hypoxia plays a significant role in determining cancer progression, treatment response, and treatment resistance. That the tumor microenvironment is highly heterogeneous with significant intratumor and intertumor variability presents a significant challenge in developing effective cancer therapies. Critical to understanding the role of the tumor microenvironment is the ability to dynamically quantify oxygen levels in the vasculature and tissue in order to elucidate the roles of oxygen supply and consumption, spatially and temporally. To this end, we describe the use of hyperspectral imaging to characterize hemoglobin absorption to quantify hemoglobin content and oxygen saturation, as well as dual emissive fluorescent/phosphorescent boron nanoparticles, which serve as ratiometric indicators of tissue oxygen tension. Applying these techniques to a window-chamber tumor model illustrates the role of fluctuations in hemoglobin saturation in driving changes in tissue oxygenation, the two being significantly correlated (r = 0.77). Finally, a green-fluorescence-protein reporter for hypoxia inducible factor-1 (HIF-1) provides an endpoint for hypoxic stress in the tumor, which is used to demonstrate a significant association between tumor hypoxia dynamics and HIF-1 activity in an in vivo demonstration of the technique.

  14. Nutrient Enrichment Drives Gulf of Mexico Hypoxia

    NASA Astrophysics Data System (ADS)

    Boesch, Donald F.; Boynton, Walter R.; Crowder, Larry B.; Diaz, Robert J.; Howarth, Robert W.; Mee, Laurence D.; Nixon, Scott W.; Rabalais, Nancy N.; Rosenberg, Rutger; Sanders, James G.; Scavia, Donald; Turner, R. Eugene

    2009-04-01

    During most summers over the past 30 years, bottom dissolved oxygen across a large area of the Louisiana and upper Texas continental shelf declined to concentrations too low (hypoxia) for most fish and large invertebrate animals to survive. This area is one of the best known “dead zones” proliferating around the world [Diaz and Rosenberg, 2008]. During July 2008, hypoxic bottom waters extended across 20,720 square kilometers (Figure 1), but they were probably even more extensive because winds from Hurricane Dolly mixed the waters off Texas before the survey could be completed. Increased inputs of nutrients (principally nitrogen and phosphorus) from the U.S. agricultural heartland within the Mississippi-Atchafalaya River Basin (MARB) are implicated in the development and spread of hypoxia in the Gulf of Mexico. Consequently, the causes of, and solutions for, hypoxia have been subjects of extensive debate and analysis. An integrated scientific assessment led to a 2001 Action Plan [Mississippi River/Gulf of Mexico Watershed Nutrient Task Force, 2001] with a goal of reducing the area of the hypoxic zone to less than 5000 square kilometers by reducing nitrogen loading [Rabalais et al., 2007].

  15. Hypoxia in the changing marine environment

    NASA Astrophysics Data System (ADS)

    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).

  16. Multiple sphingolipid abnormalities following cerebral microendothelial hypoxia

    PubMed Central

    Testai, Fernando D.; Kilkus, John P.; Berdyshev, Evgeny; Gorshkova, Irina; Natarajan, Viswanathan; Dawson, Glyn

    2015-01-01

    Hypoxia has been previously shown to inhibit the dihydroceramide (DHC) desaturase, leading to the accumulation of DHC. In this study, we used metabolic labeling with [3H]-palmitate, HPLC/MS/MS analysis, and specific inhibitors to show numerous sphingolipid changes after oxygen deprivation in cerebral microendothelial cells. The increased DHC, particularly long-chain forms, was observed in both whole cells and detergent-resistant membranes. This was reversed by reoxygenation and blocked by the de novo sphingolipid synthesis inhibitor myriocin, but not by the neutral sphingomyelinase inhibitor GW-4869. Furthermore, oxygen deprivation of microendothelial cells increased levels of dihydro-sphingosine (DH-Sph), DH-sphingosine1-phosphate (DH-S1P), DH-sphingomyelin (DH-SM), DH-glucosylceramide (DH-GlcCer), and S1P levels. In vitro assays revealed no changes in the activity of sphingomyelinases or sphingomyelin synthase, but resulted in reduced S1P lyase activity and 40% increase in glucosylceramide synthase (GCS) activity, which was reversed by reoxygenation. Inhibition of the de novo sphingolipid pathway (myriocin) or GCS (EtPoD4) induced endothelial barrier dysfunction and increased caspase 3-mediated cell death in response to hypoxia. Our findings suggest that hypoxia induces synthesis of S1P and multiple dihydrosphingolipids, including DHC, DH-SM, DH-GlcCer, DH-Sph and DH-S1P, which may be involved in ameliorating the effects of stroke. PMID:25060904

  17. Hypoxia, therapeutic resistance, and sphingosine 1-phosphate.

    PubMed

    Cuvillier, Olivier; Ader, Isabelle; Bouquerel, Pierre; Brizuela, Leyre; Gstalder, Cécile; Malavaud, Bernard

    2013-01-01

    Hypoxia, defined as a poor oxygenation, has been long recognized as a hallmark of solid tumors and a negative prognostic factor for response to therapeutics and survival of patients. Cancer cells have evolved biochemical mechanisms that allow them to react and adapt to hypoxia. At the cellular level, this adaptation is under the control of two related transcription factors, HIF-1 and HIF-2 (hypoxia-inducible factor), that respond rapidly to decreased oxygen levels to activate the expression of a broad range of genes promoting neoangiogenesis, glycolysis, metastasis, increased tumor growth, and resistance to treatments. Recent studies have identified the sphingosine kinase 1/sphingosine 1-phosphate (SphK1/S1P) signaling pathway-which elicits various cellular processes including cell proliferation, cell survival, or angiogenesis-as a new regulator of HIF-1 or HIF-2 activity. In this review, we will focus on how the inhibition/neutralization of the SphK1/S1P signaling could be exploited for cancer therapy. PMID:23290779

  18. ATM activation in hypoxia - causes and consequences

    PubMed Central

    Olcina, Monica M; Grand, Roger JA; Hammond, Ester M

    2014-01-01

    The DNA damage response is a complex signaling cascade that is triggered by cellular stress. This response is essential for the maintenance of genomic integrity and is considered to act as a barrier to the early stages of tumorigenesis. The integral role of ataxia telangiectasia mutated (ATM) kinase in the response to DNA damaging agents is well characterized; however, ATM can also be activated by non-DNA damaging agents. In fact, much has been learnt recently about the mechanism of ATM activation in response to physiologic stresses such as hypoxia that do not induce DNA damage. Regions of low oxygen concentrations that occur in solid tumors are associated with a poor prognostic outcome irrespective of treatment modality. Severe levels of hypoxia induce replication stress and trigger the activation of DNA damage response pathways including ataxia telangiectasia and Rad3-related (ATR)- and ATM-mediated signaling. In this review, we discuss hypoxia-driven ATM signaling and the possible contribution of ATM activation in this context to tumorigenesis. PMID:27308313

  19. The role of hypoxia in intestinal inflammation.

    PubMed

    Shah, Yatrik M

    2016-12-01

    Inflammatory bowel disease (IBD) is a chronic relapsing inflammatory disease of the intestine. IBD is a multifactorial disorder, and IBD-associated genes are critical in innate immune response, inflammatory response, autophagy, and epithelial barrier integrity. Moreover, epithelial oxygen tension plays a critical role in intestinal inflammation and resolution in IBD. The intestines have a dynamic and rapid fluctuation in cellular oxygen tension, which is dysregulated in IBD. Intestinal epithelial cells have a steep oxygen gradient where the tips of the villi are hypoxic and the oxygenation increases at the base of the villi. IBD results in heightened hypoxia throughout the mucosa. Hypoxia signals through a well-conserved family of transcription factors, where hypoxia-inducible factor (HIF)-1α and HIF-2α are essential in maintaining intestinal homeostasis. In inflamed mucosa, HIF-1α increases barrier protective genes, elicits protective innate immune responses, and activates an antimicrobial response through the increase in β-defensins. HIF-2α is essential in maintaining an epithelial-elicited inflammatory response and the regenerative and proliferative capacity of the intestine following an acute injury. HIF-1α activation in colitis leads to a protective response, whereas chronic activation of HIF-2α increases the pro-inflammatory response, intestinal injury, and cancer. In this mini-review, we detail the role of HIF-1α and HIF-2α in intestinal inflammation and injury and therapeutic implications of targeting HIF signaling in IBD. PMID:26812949

  20. Imaging hypoxia using 3D photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Stantz, Keith M.

    2010-02-01

    Purpose: The objective is to develop a multivariate in vivo hemodynamic model of tissue oxygenation (MiHMO2) based on 3D photoacoustic spectroscopy. Introduction: Low oxygen levels, or hypoxia, deprives cancer cells of oxygen and confers resistance to irradiation, some chemotherapeutic drugs, and oxygen-dependent therapies (phototherapy) leading to treatment failure and poor disease-free and overall survival. For example, clinical studies of patients with breast carcinomas, cervical cancer, and head and neck carcinomas (HNC) are more likely to suffer local reoccurrence and metastasis if their tumors are hypoxic. A novel method to non invasively measure tumor hypoxia, identify its type, and monitor its heterogeneity is devised by measuring tumor hemodynamics, MiHMO2. Material and Methods: Simulations are performed to compare tumor pO2 levels and hypoxia based on physiology - perfusion, fractional plasma volume, fractional cellular volume - and its hemoglobin status - oxygen saturation and hemoglobin concentration - based on in vivo measurements of breast, prostate, and ovarian tumors. Simulations of MiHMO2 are performed to assess the influence of scanner resolutions and different mathematic models of oxygen delivery. Results: Sensitivity of pO2 and hypoxic fraction to photoacoustic scanner resolution and dependencies on model complexity will be presented using hemodynamic parameters for different tumors. Conclusions: Photoacoustic CT spectroscopy provides a unique ability to monitor hemodynamic and cellular physiology in tissue, which can be used to longitudinally monitor tumor oxygenation and its response to anti-angiogenic therapies.

  1. Structural integration in hypoxia-inducible factors

    SciTech Connect

    Wu, Dalei; Potluri, Nalini; Lu, Jingping; Kim, Youngchang; Rastinejad, Fraydoon

    2015-08-20

    The hypoxia-inducible factors (HIFs) coordinate cellular adaptations to low oxygen stress by regulating transcriptional programs in erythropoiesis, angiogenesis and metabolism. These programs promote the growth and progression of many tumours, making HIFs attractive anticancer targets. Transcriptionally active HIFs consist of HIF-alpha and ARNT (also called HIF-1 beta) subunits. Here we describe crystal structures for each of mouse HIF-2 alpha-ARNT and HIF-1 alpha-ARNT heterodimers in states that include bound small molecules and their hypoxia response element. A highly integrated quaternary architecture is shared by HIF-2 alpha-ARNT and HIF-1 alpha-ARNT, wherein ARNT spirals around the outside of each HIF-alpha subunit. Five distinct pockets are observed that permit small-molecule binding, including PAS domain encapsulated sites and an interfacial cavity formed through subunit heterodimerization. The DNA-reading head rotates, extends and cooperates with a distal PAS domain to bind hypoxia response elements. HIF-alpha mutations linked to human cancers map to sensitive sites that establish DNA binding and the stability of PAS domains and pockets.

  2. Hypoxia inhibits abdominal expiratory nerve activity.

    PubMed

    Fregosi, R F; Knuth, S L; Ward, D K; Bartlett, D

    1987-07-01

    Our purpose was to examine the influence of steady-state changes in chemical stimuli, as well as discrete peripheral chemoreceptor stimulation, on abdominal expiratory motor activity. In decerebrate, paralyzed, vagotomized, and ventilated cats that had bilateral pneumothoraces, we recorded efferent activity from a phrenic nerve and from an abdominal nerve (cranial iliohypogastric nerve, L1). All cats showed phasic expiratory abdominal nerve discharge at normocapnia [end-tidal PCO2 38 +/- 2 Torr], but small doses (2-6 mg/kg) of pentobarbital sodium markedly depressed this activity. Hyperoxic hypercapnia consistently enhanced abdominal expiratory activity and shortened the burst duration. Isocapnic hypoxia caused inhibition of abdominal nerve discharge in 11 of 13 cats. Carotid sinus nerve denervation (3 cats) exacerbated the hypoxic depression of abdominal nerve activity and depressed phrenic motor output. Stimulation of peripheral chemoreceptors with NaCN increased abdominal nerve discharge in 7 of 10 cats, although 2 cats exhibited marked inhibition. Four cats with intact neuraxis, but anesthetized with ketamine, yielded qualitatively similar results. We conclude that when cats are subjected to steady-state chemical stimuli in isolation (no interference from proprioceptive inputs), hypercapnia potentiates, but hypoxia attenuates, abdominal expiratory nerve activity. Mechanisms to explain the selective inhibition of expiratory motor activity by hypoxia are proposed, and physiological implications are discussed. PMID:3624126

  3. Intrinsic cylindrical and spherical waves

    NASA Astrophysics Data System (ADS)

    Ludlow, I. K.

    2008-02-01

    Intrinsic waveforms associated with cylindrical and spherical Bessel functions are obtained by eliminating the factors responsible for the inverse radius and inverse square radius laws of wave power per unit area of wavefront. The resulting expressions are Riccati-Bessel functions for both cases and these can be written in terms of amplitude and phase functions of order v and wave variable z. When z is real, it is shown that a spatial phase angle of the intrinsic wave can be defined and this, together with its amplitude function, is systematically investigated for a range of fixed orders and varying z. The derivatives of Riccati-Bessel functions are also examined. All the component functions exhibit different behaviour in the near field depending on the order being less than, equal to or greater than 1/2. Plots of the phase angle can be used to display the locations of the zeros of the general Riccati-Bessel functions and lead to new relations concerning the ordering of the real zeros of Bessel functions and the occurrence of multiple zeros when the argument of the Bessel function is fixed.

  4. Chronic hypoxia alters mitochondrial composition in human macrophages.

    PubMed

    Fuhrmann, Dominik Christian; Wittig, Ilka; Heide, Heinrich; Dehne, Nathalie; Brüne, Bernhard

    2013-12-01

    Hypoxia inducible factors (HIFs) are important mediators of the cellular adaptive response during acute hypoxia. The role of HIF-1 and HIF-2 during prolonged periods of hypoxia, i.e. chronic hypoxia is less defined. Therefore, we used human THP-1 macrophages with a knockdown of either HIF-1α, HIF-2α, or both HIFα-subunits, incubated them for several days under hypoxia (1% O2), and analyzed responses to hypoxia using 2D-DIGE coupled to MS/MS-analysis. Chronic hypoxia was defined as a time point when the early but transient accumulation of HIFα-subunits and mRNA expression of classical HIF target genes returned towards basal levels, with a new steady state that was constant from 72h onwards. From roughly 800 spots, that were regulated comparing normoxia to chronic hypoxia, about 100 proteins were unambiguously assigned during MS/MS-analysis. Interestingly, a number of glycolytic proteins were up-regulated, while a number of inner mitochondrial membrane proteins were down-regulated independently of HIF-1α or HIF-2α. Chronic hypoxic conditions depleted the mitochondrial mass by autophagy, which occurred independently of HIF proteins. Macrophages tolerate periods of chronic hypoxia very well and adaptive responses occur, at least in part, independently of HIF-1α and/or HIF-2α and comprise mitophagy as a pathway of particular importance. PMID:24140568

  5. Diastolic dysfunction precedes hypoxia-induced mortality in dystrophic mice

    PubMed Central

    Townsend, DeWayne

    2015-01-01

    Duchenne muscular dystrophy (DMD) is a progressive striated muscle disease that is characterized by skeletal muscle weakness with progressive respiratory and cardiac failure. Together respiratory and cardiac disease account for the majority of mortality in the DMD patient population. However, little is known regarding the effects of respiratory dysfunction on the dystrophic heart. The studies described here examine the effects of acute hypoxia on cardiac function. These studies demonstrate, for the first time, that a mouse model of DMD displays significant mortality following acute exposure to hypoxia. This mortality is characterized by a steady decline in systolic function. Retrospective analysis reveals that significant decreases in diastolic dysfunction, especially in the right ventricle, precede the decline in systolic pressure. The initial hemodynamic response to acute hypoxia in the mouse is similar to that observed in larger species, with significant increases in right ventricular afterload and decreases in left ventricular preload being observed. Significant increases in heart rate and contractility suggest hypoxia-induced activation of the sympathetic nervous system. These studies provide evidence that while hypoxia presents significant hemodynamic challenges to the dystrophic right ventricle, global cardiac dysfunction precedes hypoxia-induced mortality in the dystrophic heart. These findings are clinically relevant as the respiratory insufficiency evident in patients with DMD results in significant bouts of hypoxia. The results of these studies indicate that hypoxia may contribute to the acceleration of the heart disease in DMD patients. Importantly, hypoxia can be avoided through the use of ventilatory support. PMID:26311833

  6. Prolonged lobar hypoxia in vivo enhances the responsivity of isolated pulmonary veins to hypoxia

    NASA Technical Reports Server (NTRS)

    Sheehan, D. W.; Farhi, L. E.; Russell, J. A.

    1992-01-01

    The hypoxic response of pulmonary vessels isolated from eight sheep whose right apical lobes (RAL) had inspired 100% N2 for 20 h was studied. The RAL of these conscious sheep inspired hypoxic gas and the remainder of the lung inspired air. During hypoxia, RAL perfusion was 33 +/- 3% of its air value, carotid arterial PO2 averaged 86 +/- 3 mm Hg and pulmonary perfusion pressure was not significantly different from the initial control period when the RAL inspired air. At the end of the hypoxic exposure, the sheep were killed, and pulmonary artery and vein rings (0.5 to 2 mm inner diameter) were isolated from both the RAL and the right cardiac lobe, which served as the control lobe (CL). Arteries from the RAL and CL did not contract in response to 6% O2/6% CO2/88% N2 (hypoxia). In contrast, RAL veins did contract vigorously in response to hypoxia, whereas CL veins did not contract or contracted only minimally. Rubbing of the endothelium or prior incubation of RAL veins with catalase (1,200 units/ml), indomethacin (10(-5) M), or the thromboxane A2/prostaglandin H2 (TxA2/PGH2) receptor antagonist, SQ 29,548 (3 X 10(-6) M) each significantly reduced the response to hypoxia. RAL veins were also found to be more reactive than CL veins to the prostaglandin endoperoxide analogue U46619. We conclude that prolonged lobar hypoxia in vivo increases the responsivity of isolated pulmonary veins to hypoxia. These contractions may result from an increase in reactive O2 species, which in turn modify production of, metabolism of, and/or tissue responsivity to TxA2/PGH2.

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

    PubMed

    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. PMID

  8. Repeated acute hypoxia temporarily attenuates the ventilatory respiratory response to hypoxia in conscious newborn rats.

    PubMed

    Matsuoka, T; Yoda, T; Ushikubo, S; Matsuzawa, S; Sasano, T; Komiyama, A

    1999-07-01

    We asked whether repeated hypoxic exposures during the early neonatal periods could affect the ventilatory control, such as the lung volume-dependent ventilatory inhibition (HBR), pulmonary ventilation (VE), and CO2 production (VCO2). Within each litter of rats, one group of pups (experimental group H) was exposed to 6% O2 (30-min duration twice a day from postnatal d 1 to 4). The other group (control group C) was exposed to air. At 5 d after birth, the HBR was triggered by lung inflation via negative body surface pressure (10 cm H2O). Measurements of VE and VCO2 were done by plethysmography and the inflow-outflow CO2 difference, respectively. At 2 wk of age, VE and VCO2 measurements were repeated by the barometric technique and the inflow-outflow CO2 difference, respectively. Each conscious pup was breathing normoxia (21% O2) and then hypoxia (10% O2). Results were as follows: 1) during normoxia, HBR was stronger and both VE and VCO2 were higher in H pups than in C pups; 2) during hypoxia, the HBR of C was as in normoxia, whereas that of H was increased above the normoxic value; 3) during hypoxia, C maintained VE, whereas H decreased it; 4) in hypoxia, VCO2 was reduced significantly in both groups; 5) at 2 wk of age, VE and VCO2 did not differ between H and C during normoxia or in response to 10% hypoxia. We conclude that in rat pups, repeated hypoxic episodes can modify the HBR and, at least temporarily, reduce the VE response to hypoxia with a decrease in VCO2. The findings are in agreement with the view that repeated hypoxic exposures in the neonatal period could interfere with the development of respiratory control and could possibly be involved in the mechanisms of neonatal apnea or sudden infant death syndrome. PMID:10400145

  9. Hypoxia-induced DNA hypermethylation in human pulmonary fibroblasts is associated with Thy-1 promoter methylation and the development of a pro-fibrotic phenotype

    PubMed Central

    2012-01-01

    Background Pulmonary fibrosis is a debilitating and lethal disease with no effective treatment options. Understanding the pathological processes at play will direct the application of novel therapeutic avenues. Hypoxia has been implicated in the pathogenesis of pulmonary fibrosis yet the precise mechanism by which it contributes to disease progression remains to be fully elucidated. It has been shown that chronic hypoxia can alter DNA methylation patterns in tumour-derived cell lines. This epigenetic alteration can induce changes in cellular phenotype with promoter methylation being associated with gene silencing. Of particular relevance to idiopathic pulmonary fibrosis (IPF) is the observation that Thy-1 promoter methylation is associated with a myofibroblast phenotype where loss of Thy-1 occurs alongside increased alpha smooth muscle actin (α-SMA) expression. The initial aim of this study was to determine whether hypoxia regulates DNA methylation in normal human lung fibroblasts (CCD19Lu). As it has been reported that hypoxia suppresses Thy-1 expression during lung development we also studied the effect of hypoxia on Thy-1 promoter methylation and gene expression. Methods CCD19Lu were grown for up to 8 days in hypoxia and assessed for global changes in DNA methylation using flow cytometry. Real-time PCR was used to quantify expression of Thy-1, α-SMA, collagen I and III. Genomic DNA was bisulphite treated and methylation specific PCR (MSPCR) was used to examine the methylation status of the Thy-1 promoter. Results Significant global hypermethylation was detected in hypoxic fibroblasts relative to normoxic controls and was accompanied by increased expression of myofibroblast markers. Thy-1 mRNA expression was suppressed in hypoxic cells, which was restored with the demethylating agent 5-aza-2′-deoxycytidine. MSPCR revealed that Thy-1 became methylated following fibroblast exposure to 1% O2. Conclusion These data suggest that global and gene-specific changes in

  10. Short-term supplementation with alpha-ketoglutaric acid and 5-hydroxymethylfurfural does not prevent the hypoxia induced decrease of exercise performance despite attenuation of oxidative stress.

    PubMed

    Gatterer, H; Greilberger, J; Philippe, M; Faulhaber, M; Djukic, R; Burtscher, M

    2013-01-01

    Reactive oxygen species are thought to partly be responsible for the hypoxia induced performance decrease. The present study evaluated the effects of a broad based antioxidant supplementation or the combined intake of alpha-ketoglutaric acid (α-KG) and 5-hydroxymethylfurfural (5-HMF) on the performance decrease at altitude. 18 healthy, well-trained males (age: 25±3 years; height: 179±6 cm; weight: 76.4±6.8 kg) were randomly assigned in a double-blind fashion to a placebo group (PL), a α-KG and 5-HMF supplementation group (AO1) or a broad based antioxidant supplementation group (AO2). Participants performed 2 incremental exercise tests to exhaustion on a cycle ergometer; the first test under normoxia and the second under hypoxia conditions (simulated altitude, FiO2=13% ~ 4 300 m). Supplementation started 48 h before the hypoxia test. Maximal oxygen uptake, maximal power output, power output at the ventilatory and lactate threshold and the tissue oxygenation index (NIRS) were measured under both conditions. Oxidative stress markers were measured before the supplementation and after the hypoxia test. Under hypoxia conditions all performance parameters decreased in the range of 19-39% with no differences between groups. A significant change from normoxia to hypoxia (p<0.001) and between groups (p=0.038) were found for the tissue oxygenation index. Post hoc test revealed significant differences between the PL and both, the AO1 and the AO2 group. The oxidative stress parameter carbonyl protein changed from normoxia to hypoxia in all participants and 4-hydroxynonenal decreased in the AO1 group only. In conclusion the results suggest that short-term supplementation with an antioxidant does not prevent the performance decrease at altitude. However, positive effects on muscle oxygen extraction, as indicated by the tissue oxygenation index, might indicate that mitochondrial functioning was actually influenced by the supplementation. PMID:22893323

  11. Preconditioning of Cardiosphere-Derived Cells With Hypoxia or Prolyl-4-Hydroxylase Inhibitors Increases Stemness and Decreases Reliance on Oxidative Metabolism.

    PubMed

    Tan, Suat Cheng; Gomes, Renata S M; Yeoh, Kar Kheng; Perbellini, Filippo; Malandraki-Miller, Sophia; Ambrose, Lucy; Heather, Lisa C; Faggian, Giuseppe; Schofield, Christopher J; Davies, Kay E; Clarke, Kieran; Carr, Carolyn A

    2016-01-01

    Cardiosphere-derived cells (CDCs), which can be isolated from heart explants, are a promising candidate cell source for infarcted myocardium regeneration. However, current protocols used to expand CDCs require at least 1 month in vitro to obtain sufficient cells for transplantation. We report that CDC culture can be optimized by preconditioning the cells under hypoxia (2% oxygen), which may reflect the physiological oxygen level of the stem cell niche. Under hypoxia, the CDC proliferation rate increased by 1.4-fold, generating 6 × 10(6) CDCs with higher expression of cardiac stem cell and pluripotency gene markers compared to normoxia. Furthermore, telomerase (TERT), cytokines/ligands involved in stem cell trafficking (SDF/CXCR-4), erythropoiesis (EPO), and angiogenesis (VEGF) were increased under hypoxia. Hypoxic preconditioning was mimicked by treatment with two types of hypoxia-inducible factor (HIF) prolyl-4-hydroxylase inhibitors (PHDIs): dimethyloxaloylglycine (DMOG) and 2-(1-chloro-4-hydroxyisoquinoline-3-carboxamido) acetic acid (BIC). Despite the difference in specificity, both PHDIs significantly increased c-Kit expression and activated HIF, EPO, and CXCR-4. Furthermore, treatment with PHDIs for 24 h increased cell proliferation. Notably, all hypoxic and PHDI-preconditioned CDCs had decreased oxygen consumption and increased glycolytic metabolism. In conclusion, cells cultured under hypoxia could have potentially enhanced therapeutic potential, which can be mimicked, in part, by PHDIs. PMID:25751158

  12. [Interpretation of hemostatic and fibrinolytic markers].

    PubMed

    Asakura, Hidesaku

    2011-10-01

    Blood dose not normally coagulate in the blood vessels covered with endothelial cells, because these cells contain some substances responsible for antithrombotic action such as thrombomodulin, heparin-like substance, prostacyclin, nitric oxide and tissue plasminogen activator. Most important role of blood coagulation is hemostasis. Blood can coagulate in two ways: intrinsic coagulation pathway and extrinsic coagulation pathway that is activated by negatively charged substances and FVIIa-tissue-factor (TF) complex, respectively. Prothrombin time(PT) can represent extrinsic pathway, while activated partial thromboplastin time (APTT) can represent intrinsic pathway. PT is prolonged in such diseases as vitamin K deficiency, hepatic failure and warfarin intake, while APTT is prolonged such diseases as hemophilia A & B, von Willebrand disease and lupus anticoagulant. Cross mixing test is very useful to assess prolonged clotting time. FDP means fibrin/fibrinogen degradation products and D-dimer is the smallest products of fibrin degradation. These markers are often used to diagnose disseminated intravascular coagulation (DIC) and deep vein thrombosis (DVT). Thrombin-antithrombin complex (TAT) and plasmin-alpha2 plasmin inhibitor (PIC) can be used to evaluate the extent of coagulation and fibrinolysis activation, respectively. These two markers is essential for classify the pathophysiology of DIC: DIC with suppressed fibrinolysis, enhanced fibrinolysis or balanced fibrinolysis. In conclusion, exact interpretation of hemostatic and fibrinolytic markers is one of the most important abilities in clinical situation. PMID:22184880

  13. Intrinsic rotation with gyrokinetic models

    SciTech Connect

    Parra, Felix I.; Barnes, Michael; Catto, Peter J.; Calvo, Ivan

    2012-05-15

    The generation of intrinsic rotation by turbulence and neoclassical effects in tokamaks is considered. To obtain the complex dependences observed in experiments, it is necessary to have a model of the radial flux of momentum that redistributes the momentum within the tokamak in the absence of a preexisting velocity. When the lowest order gyrokinetic formulation is used, a symmetry of the model precludes this possibility, making small effects in the gyroradius over scale length expansion necessary. These effects that are usually small become important for momentum transport because the symmetry of the lowest order gyrokinetic formulation leads to the cancellation of the lowest order momentum flux. The accuracy to which the gyrokinetic equation needs to be obtained to retain all the physically relevant effects is discussed.

  14. Chronic intermittent hypoxia exposure-induced atherosclerosis: a brief review.

    PubMed

    Song, Dongmei; Fang, Guoqiang; Greenberg, Harly; Liu, Shu Fang

    2015-12-01

    Obstructive sleep apnea (OSA) is highly prevalent in the USA and is recognized as an independent risk factor for atherosclerotic cardiovascular disease. Identification of atherosclerosis risk factor attributable to OSA may provide opportunity to develop preventive measures for cardiovascular risk reduction. Chronic intermittent hypoxia (CIH) is a prominent feature of OSA pathophysiology and may be a major mechanism linking OSA to arteriosclerosis. Animal studies demonstrated that CIH exposure facilitated high-cholesterol diet (HCD)-induced atherosclerosis, accelerated the progression of existing atherosclerosis, and induced atherosclerotic lesions in the absence of other atherosclerosis risk factors, demonstrating that CIH is an independent causal factor of atherosclerosis. Comparative studies revealed major differences between CIH-induced and the classic HCD-induced atherosclerosis. Systemically, CIH was a much weaker inducer of atherosclerosis. CIH and HCD differentially activated inflammatory pathways. Histologically, CIH-induced atherosclerotic plaques had no clear necrotic core, contained a large number of CD31+ endothelial cells, and had mainly elastin deposition, whereas HCD-induced plaques had typical necrotic cores and fibrous caps, contained few endothelial cells, and had mainly collagen deposition. Metabolically, CIH caused mild, but HCD caused more severe dyslipidemia. Mechanistically, CIH did not, but HCD did, cause macrophage foam cell formation. NF-κB p50 gene deletion augmented CIH-induced, but not HCD-induced atherosclerosis. These differences reflect the intrinsic differences between the two types of atherosclerosis in terms of pathological nature and underlying mechanisms and support the notion that CIH-induced atherosclerosis is a new paradigm that differs from the classic HCD-induced atherosclerosis. PMID:26407987

  15. Regression of Lung Cancer by Hypoxia Sensitizing Ruthenium Polypyridyl Complexes

    PubMed Central

    Yadav, Abhishek; Janaratne, Thamara; Krishnan, Arthi; Singhal, Sharad S.; Yadav, Sushma; Dayoub, Adam S.; Hawkins, Doyle L.; Awasthi, Sanjay; MacDonnell, Frederick M.

    2013-01-01

    The ruthenium (II) polypyridyl complexes (RPCs) Δ-[(phen)2Ru(tatpp)]Cl2 (Δ-[3]Cl2) and ΔΔ-[(phen)2Ru(tatpp)Ru(phen)2]Cl4 (ΔΔ-[4]Cl4) are a new generation of metal-based anti-tumor agents. These RPCs bind DNA via intercalation of the tatpp ligand which itself is redox-active and easily reduced at biologically relevant potentials. We have previously shown that RPC 44+ cleaves DNA when reduced by glutathione to a radical species, and that this DNA cleavage is potentiated under hypoxic conditions in vitro. Here we show that 32+ also exhibits free-radical mediated DNA cleavage in vitro, and that 32+ and 44+ both exhibit selective cytotoxicity towards cultured malignant cell lines, and marked inhibition of tumor growth in vivo. The murine acute toxicity of RPCs 32+ and 44+ (maximum tolerable doses (MTD’s) ~ 65 µmol/kg) is comparable with that for cisplatin (LD50 ~57 µmol/kg) but unlike cisplatin, RPC’s are generally cleared from the body unchanged via renal excretion without appreciable metabolism or nephrotoxic side effects. RPCs 32+ and 44+ are demonstrated to suppress growth of human non-small cell lung carcinoma (~83%), show potentiated cytotoxicity in vitro under hypoxic conditions, and induce apoptosis through both intrinsic and extrinsic pathways. The novel hypoxia-enhanced DNA cleavage activity and biological activity suggest a promising new anti-cancer pharmacophore based on metal complexes with aromatic ligands that are easily reduced at biologically accessible potentials. PMID:23443803

  16. Post-traumatic hypoxia exacerbates brain tissue damage: analysis of axonal injury and glial responses.

    PubMed

    Hellewell, Sarah C; Yan, Edwin B; Agyapomaa, Doreen A; Bye, Nicole; Morganti-Kossmann, M Cristina

    2010-11-01

    Traumatic brain injury (TBI) resulting in poor neurological outcome is predominantly associated with diffuse brain damage and secondary hypoxic insults. Post-traumatic hypoxia is known to exacerbate primary brain injury; however, the underlying pathological mechanisms require further elucidation. Using a rat model of diffuse traumatic axonal injury (TAI) followed by a post-traumatic hypoxic insult, we characterized axonal pathology, macrophage/microglia accumulation, and astrocyte responses over 14 days. Rats underwent TAI alone, TAI followed by 30 min of hypoxia (TAI + Hx), hypoxia alone, or sham-operation (n = 6/group). Systemic hypoxia was induced by ventilating rats with 12% oxygen in nitrogen, resulting in a ∼ 50% reduction in arterial blood oxygen saturation. Brains were assessed for axonal damage, macrophage/microglia accumulation, and astrocyte activation at 1, 7, and 14 days post-treatment. Immunohistochemistry with axonal damage markers (β-amyloid precursor protein [β-APP] and neurofilament) showed strong positive staining in TAI + Hx rats, which was most prominent in the corpus callosum (retraction bulbs 69.8 ± 18.67; swollen axons 14.2 ± 5.25), and brainstem (retraction bulbs 294 ± 118.3; swollen axons 50.3 ± 20.45) at 1 day post-injury. Extensive microglia/macrophage accumulation detected with the CD68 antibody was maximal at 14 days post-injury in the corpus callosum (macrophages 157.5 ± 55.48; microglia 72.71 ± 20.75), and coincided with regions of axonal damage. Astrocytosis assessed with glial fibrillary acidic protein (GFAP) antibody was also abundant in the corpus callosum and maximal at 14 days, with a trend toward an increase in TAI + Hx animals (18.99 ± 2.45 versus 13.56 ± 0.81; p = 0.0617). This study demonstrates for the first time that a hypoxic insult following TAI perpetuates axonal pathology and cellular inflammation, which may account for the poor neurological outcomes seen in TBI patients who experience post

  17. The physiological effects of hypobaric hypoxia versus normobaric hypoxia: a systematic review of crossover trials.

    PubMed

    Coppel, Jonny; Hennis, Philip; Gilbert-Kawai, Edward; Grocott, Michael Pw

    2015-01-01

    Much hypoxia research has been carried out at high altitude in a hypobaric hypoxia (HH) environment. Many research teams seek to replicate high-altitude conditions at lower altitudes in either hypobaric hypoxic conditions or normobaric hypoxic (NH) laboratories. Implicit in this approach is the assumption that the only relevant condition that differs between these settings is the partial pressure of oxygen (PO2), which is commonly presumed to be the principal physiological stimulus to adaptation at high altitude. This systematic review is the first to present an overview of the current available literature regarding crossover studies relating to the different effects of HH and NH on human physiology. After applying our inclusion and exclusion criteria, 13 studies were deemed eligible for inclusion. Several studies reported a number of variables (e.g. minute ventilation and NO levels) that were different between the two conditions, lending support to the notion that true physiological difference is indeed present. However, the presence of confounding factors such as time spent in hypoxia, temperature, and humidity, and the limited statistical power due to small sample sizes, limit the conclusions that can be drawn from these findings. Standardisation of the study methods and reporting may aid interpretation of future studies and thereby improve the quality of data in this area. This is important to improve the quality of data that is used for improving the understanding of hypoxia tolerance, both at altitude and in the clinical setting. PMID:25722851

  18. REST is a hypoxia-responsive transcriptional repressor.

    PubMed

    Cavadas, Miguel A S; Mesnieres, Marion; Crifo, Bianca; Manresa, Mario C; Selfridge, Andrew C; Keogh, Ciara E; Fabian, Zsolt; Scholz, Carsten C; Nolan, Karen A; Rocha, Liliane M A; Tambuwala, Murtaza M; Brown, Stuart; Wdowicz, Anita; Corbett, Danielle; Murphy, Keith J; Godson, Catherine; Cummins, Eoin P; Taylor, Cormac T; Cheong, Alex

    2016-01-01

    Cellular exposure to hypoxia results in altered gene expression in a range of physiologic and pathophysiologic states. Discrete cohorts of genes can be either up- or down-regulated in response to hypoxia. While the Hypoxia-Inducible Factor (HIF) is the primary driver of hypoxia-induced adaptive gene expression, less is known about the signalling mechanisms regulating hypoxia-dependent gene repression. Using RNA-seq, we demonstrate that equivalent numbers of genes are induced and repressed in human embryonic kidney (HEK293) cells. We demonstrate that nuclear localization of the Repressor Element 1-Silencing Transcription factor (REST) is induced in hypoxia and that REST is responsible for regulating approximately 20% of the hypoxia-repressed genes. Using chromatin immunoprecipitation assays we demonstrate that REST-dependent gene repression is at least in part mediated by direct binding to the promoters of target genes. Based on these data, we propose that REST is a key mediator of gene repression in hypoxia. PMID:27531581

  19. Mitochondrial Reactive Oxygen Species Trigger Hypoxia-Induced Transcription

    NASA Astrophysics Data System (ADS)

    Chandel, N. S.; Maltepe, E.; Goldwasser, E.; Mathieu, C. E.; Simon, M. C.; Schumacker, P. T.

    1998-09-01

    Transcriptional activation of erythropoietin, glycolytic enzymes, and vascular endothelial growth factor occurs during hypoxia or in response to cobalt chloride (CoCl2) in Hep3B cells. However, neither the mechanism of cellular O2 sensing nor that of cobalt is fully understood. We tested whether mitochondria act as O2 sensors during hypoxia and whether hypoxia and cobalt activate transcription by increasing generation of reactive oxygen species (ROS). Results show (i) wild-type Hep3B cells increase ROS generation during hypoxia (1.5% O2) or CoCl2 incubation, (ii) Hep3B cells depleted of mitochondrial DNA (ρ 0 cells) fail to respire, fail to activate mRNA for erythropoietin, glycolytic enzymes, or vascular endothelial growth factor during hypoxia, and fail to increase ROS generation during hypoxia; (iii) ρ 0 cells increase ROS generation in response to CoCl2 and retain the ability to induce expression of these genes; and (iv) the antioxidants pyrrolidine dithiocarbamate and ebselen abolish transcriptional activation of these genes during hypoxia or CoCl2 in wild-type cells, and abolish the response to CoCl2 in ρ 0 cells. Thus, hypoxia activates transcription via a mitochondria-dependent signaling process involving increased ROS, whereas CoCl2 activates transcription by stimulating ROS generation via a mitochondria-independent mechanism.

  20. Efficient utilization of aerobic metabolism helps Tibetan locusts conquer hypoxia

    PubMed Central

    2013-01-01

    Background Responses to hypoxia have been investigated in many species; however, comparative studies between conspecific geographical populations at different altitudes are rare, especially for invertebrates. The migratory locust, Locusta migratoria, is widely distributed around the world, including on the high-altitude Tibetan Plateau (TP) and the low-altitude North China Plain (NP). TP locusts have inhabited Tibetan Plateau for over 34,000 years and thus probably have evolved superior capacity to cope with hypoxia. Results Here we compared the hypoxic responses of TP and NP locusts from morphological, behavioral, and physiological perspectives. We found that TP locusts were more tolerant of extreme hypoxia than NP locusts. To evaluate why TP locusts respond to extreme hypoxia differently from NP locusts, we subjected them to extreme hypoxia and compared their transcriptional responses. We found that the aerobic metabolism was less affected in TP locusts than in NP locusts. RNAi disruption of PDHE1β, an entry gene from glycolysis to TCA cycle, increased the ratio of stupor in TP locusts and decreased the ATP content of TP locusts in hypoxia, confirming that aerobic metabolism is critical for TP locusts to maintain activity in hypoxia. Conclusions Our results indicate that TP and NP locusts have undergone divergence in hypoxia tolerance. These findings also indicate that insects can adapt to hypoxic pressure by modulating basic metabolic processes. PMID:24047108

  1. REST is a hypoxia-responsive transcriptional repressor

    PubMed Central

    Cavadas, Miguel A. S.; Mesnieres, Marion; Crifo, Bianca; Manresa, Mario C.; Selfridge, Andrew C.; Keogh, Ciara E.; Fabian, Zsolt; Scholz, Carsten C.; Nolan, Karen A.; Rocha, Liliane M. A.; Tambuwala, Murtaza M.; Brown, Stuart; Wdowicz, Anita; Corbett, Danielle; Murphy, Keith J.; Godson, Catherine; Cummins, Eoin P.; Taylor, Cormac T.; Cheong, Alex

    2016-01-01

    Cellular exposure to hypoxia results in altered gene expression in a range of physiologic and pathophysiologic states. Discrete cohorts of genes can be either up- or down-regulated in response to hypoxia. While the Hypoxia-Inducible Factor (HIF) is the primary driver of hypoxia-induced adaptive gene expression, less is known about the signalling mechanisms regulating hypoxia-dependent gene repression. Using RNA-seq, we demonstrate that equivalent numbers of genes are induced and repressed in human embryonic kidney (HEK293) cells. We demonstrate that nuclear localization of the Repressor Element 1-Silencing Transcription factor (REST) is induced in hypoxia and that REST is responsible for regulating approximately 20% of the hypoxia-repressed genes. Using chromatin immunoprecipitation assays we demonstrate that REST-dependent gene repression is at least in part mediated by direct binding to the promoters of target genes. Based on these data, we propose that REST is a key mediator of gene repression in hypoxia. PMID:27531581

  2. Blockade of processing/activation of caspase-3 by hypoxia

    SciTech Connect

    Han, Sang Hee; Kim, Moonil; Park, Kyoungsook; Kim, Tae-Hyoung; Seol, Dai-Wu

    2008-10-31

    Tumor hypoxia, which is caused by the rapid proliferation of tumor cells and aberrant vasculature in tumors, results in inadequate supplies of oxygen and nutrients to tumor cells. Paradoxically, these unfavorable growth conditions benefit tumor cell survival, although the mechanism is poorly understood. We have demonstrated for the first time that hypoxia inhibits TRAIL-induced apoptosis by blocking translocation of Bax from cytosol to the mitochondria in tumor cells. However, it is largely unknown how hypoxia-inhibited Bax translocation attenuates TRAIL-induced apoptosis. Here, we demonstrate that despite its inhibitory activity in TRAIL-induced apoptosis, hypoxia does not affect TRAIL-triggered proximal apoptotic signaling events, including caspase-8 activation and Bid cleavage. Instead, hypoxia inhibited processing of caspase-3, leading to incomplete activation of the caspase. Importantly, hypoxia-blocked translocation of Bax to the mitochondria significantly inhibited releasing the mitochondrial factors, such as cytochrome c and Smac/DIABLO, to the cytosol in response to TRAIL. It is well-known that complete processing/activation of caspase-3 requires Smac/DIABLO released from mitochondria. Therefore, our data indicate that an engagement of the apoptotic mitochondrial events leading to caspase-3 activation is blocked by hypoxia. Our data shed new light on understanding of the apoptotic signal transduction and targets regulated by tumor hypoxia.

  3. Cognitive responses to hypobaric hypoxia: implications for aviation training

    PubMed Central

    Neuhaus, Christopher; Hinkelbein, Jochen

    2014-01-01

    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. PMID:25419162

  4. Transcriptional response to hypoxia in the aquatic fungus Blastocladiella emersonii.

    PubMed

    Camilo, César M; Gomes, Suely L

    2010-06-01

    Global gene expression analysis was carried out with Blastocladiella emersonii cells subjected to oxygen deprivation (hypoxia) using cDNA microarrays. In experiments of gradual hypoxia (gradual decrease in dissolved oxygen) and direct hypoxia (direct decrease in dissolved oxygen), about 650 differentially expressed genes were observed. A total of 534 genes were affected directly or indirectly by oxygen availability, as they showed recovery to normal expression levels or a tendency to recover when cells were reoxygenated. In addition to modulating many genes with no putative assigned function, B. emersonii cells respond to hypoxia by readjusting the expression levels of genes responsible for energy production and consumption. At least transcriptionally, this fungus seems to favor anaerobic metabolism through the upregulation of genes encoding glycolytic enzymes and lactate dehydrogenase and the downregulation of most genes coding for tricarboxylic acid (TCA) cycle enzymes. Furthermore, genes involved in energy-costly processes, like protein synthesis, amino acid biosynthesis, protein folding, and transport, had their expression profiles predominantly downregulated during oxygen deprivation, indicating an energy-saving effort. Data also revealed similarities between the transcriptional profiles of cells under hypoxia and under iron(II) deprivation, suggesting that Fe(2+) ion could have a role in oxygen sensing and/or response to hypoxia in B. emersonii. Additionally, treatment of fungal cells prior to hypoxia with the antibiotic geldanamycin, which negatively affects the stability of mammalian hypoxia transcription factor HIF-1alpha, caused a significant decrease in the levels of certain upregulated hypoxic genes. PMID:20418381

  5. Thermoregulatory and metabolic responses of Japanese quail to hypoxia

    PubMed Central

    Atchley, Dylan S.; Foster, Jennifer A.; Bavis, Ryan W.

    2008-01-01

    Common responses to hypoxia include decreased body temperature (Tb) and decreased energy metabolism. In this study, the effects of hypoxia and hypercapnia on Tb and metabolic oxygen consumption (V̇o2) were investigated in Japanese quail (Coturnix japonica). When exposed to hypoxia (15, 13, 11 and 9% O2), Tb decreased only at 11% and 9% O2 compared to normoxia; quail were better able to maintain Tb during acute hypoxia after a one-week acclimation to 10% O2. V̇o2 also decreased during hypoxia, but at 9% O2 this was partially offset by increased anaerobic metabolism. Tb and V̇o2 responses to 9% O2 were exaggerated at lower ambient temperature (Ta), reflecting a decreased lower critical temperature during hypoxia. Conversely, hypoxia had little effect on Tb or V̇o2 at higher Ta (36°C). We conclude that Japanese quail respond to hypoxia in much the same way as mammals, by reducing both Tb and V̇o2. No relationship was found between the magnitudes of decreases in Tb and V̇o2 during 9% O2, however. Since metabolism is the source of heat generation, this suggests that Japanese quail increase thermolysis to reduce Tb. During hypercapnia (3, 6 and 9% CO2), Tb was reduced only at 9% CO2 while V̇o2 was unchanged. PMID:18727957

  6. Issues in Purchasing and Maintaining Intrinsic Standards

    SciTech Connect

    PETTIT,RICHARD B.; JAEGER,KLAUS; EHRLICH,CHARLES D.

    2000-09-12

    Intrinsic standards are widely used in the metrology community because they realize the best level uncertainty for many metrology parameters. For some intrinsic standards, recommended practices have been developed to assist metrologists in the selection of equipment and the development of appropriate procedures in order to realize the intrinsic standard. As with the addition of any new standard, the metrology laboratory should consider the pros and cons relative to their needs before purchasing the standard so that the laboratory obtains the maximum benefit from setting up and maintaining these standards. While the specific issues that need to be addressed depend upon the specific intrinsic standard and the level of realization, general issues that should be considered include ensuring that the intrinsic standard is compatible with the laboratory environment, that the standard is compatible with the current and future workload, and whether additional support standards will be required in order to properly maintain the intrinsic standard. When intrinsic standards are used to realize the best level of uncertainty for a specific metrology parameter, they usually require critical and important maintenance activities. These activities can including training of staff in the system operation, as well as safety procedures; performing periodic characterization measurements to ensure proper system operation; carrying out periodic intercomparisons with similar intrinsic standards so that proper operation is demonstrated; and maintaining control or trend charts of system performance. This paper has summarized many of these important issues and therefore should be beneficial to any laboratory that is considering the purchase of an intrinsic standard.

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

    PubMed

    Feriche, Belén; García-Ramos, Amador; Calderón-Soto, Carmen; Drobnic, Franchek; Bonitch-Góngora, Juan G; Galilea, Pedro A; Riera, Joan; Padial, Paulino

    2014-01-01

    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. PMID:25474104

  8. Effect of Acute Exposure to Moderate Altitude on Muscle Power: Hypobaric Hypoxia vs. Normobaric Hypoxia

    PubMed Central

    Feriche, Belén; García-Ramos, Amador; Calderón-Soto, Carmen; Drobnic, Franchek; Bonitch- Góngora, Juan G.; Galilea, Pedro A.; Riera, Joan; Padial, Paulino

    2014-01-01

    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 Pmean obtained across the complete force-velocity curve. Our findings indicate a significantly higher absolute load linked to Pmax (∼3%) and maximal strength (1RM) (∼6%) in G1 attributable to the climb to altitude (P<0.05). We also observed a stimulating effect of natural hypoxia on Pmean and Ppeak 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 1RM, movement velocity and power during the execution of a force-velocity curve in bench press. PMID:25474104

  9. 2014 Gulf of Mexico Hypoxia Forecast

    USGS Publications Warehouse

    Scavia, Donald; Evans, Mary Anne; Obenour, Dan

    2014-01-01

    The Gulf of Mexico annual summer hypoxia forecasts are based on average May total nitrogen loads from the Mississippi River basin for that year. The load estimate, recently released by USGS, is 4,761 metric tons per day. Based on that estimate, we predict the area of this summer’s hypoxic zone to be 14,000 square kilometers (95% credible interval, 8,000 to 20,000) – an “average year”. Our forecast hypoxic volume is 50 km3 (95% credible interval, 20 to 77).

  10. 2013 Gulf of Mexico Hypoxia Forecast

    USGS Publications Warehouse

    Scavia, Donald; Evans, Mary Anne; Obenour, Dan

    2013-01-01

    The Gulf of Mexico annual summer hypoxia forecasts are based on average May total nitrogen loads from the Mississippi River basin for that year. The load estimate, recently released by USGS, is 7,316 metric tons per day. Based on that estimate, we predict the area of this summer’s hypoxic zone to be 18,900 square kilometers (95% credible interval, 13,400 to 24,200), the 7th largest reported and about the size of New Jersey. Our forecast hypoxic volume is 74.5 km3 (95% credible interval, 51.5 to 97.0), also the 7th largest on record.

  11. Hypoxia causes transgenerational impairments in reproduction of fish.

    PubMed

    Wang, Simon Yuan; Lau, Karen; Lai, Keng-Po; Zhang, Jiang-Wen; Tse, Anna Chung-Kwan; Li, Jing-Woei; Tong, Yin; Chan, Ting-Fung; Wong, Chris Kong-Chu; Chiu, Jill Man-Ying; Au, Doris Wai-Ting; Wong, Alice Sze-Tsai; Kong, Richard Yuen-Chong; Wu, Rudolf Shiu-Sun

    2016-01-01

    Hypoxia is amongst the most widespread and pressing problems in aquatic environments. Here we demonstrate that fish (Oryzias melastigma) exposed to hypoxia show reproductive impairments (retarded gonad development, decrease in sperm count and sperm motility) in F1 and F2 generations despite these progenies (and their germ cells) having never been exposed to hypoxia. We further show that the observed transgenerational reproductive impairments are associated with a differential methylation pattern of specific genes in sperm of both F0 and F2 coupled with relevant transcriptomic and proteomic alterations, which may impair spermatogenesis. The discovered transgenerational and epigenetic effects suggest that hypoxia might pose a dramatic and long-lasting threat to the sustainability of fish populations. Because the genes regulating spermatogenesis and epigenetic modifications are highly conserved among vertebrates, these results may also shed light on the potential transgenerational effects of hypoxia on other vertebrates, including humans. PMID:27373813

  12. Hypoxia causes transgenerational impairments in reproduction of fish

    PubMed Central

    Wang, Simon Yuan; Lau, Karen; Lai, Keng-Po; Zhang, Jiang-Wen; Tse, Anna Chung-Kwan; Li, Jing-Woei; Tong, Yin; Chan, Ting-Fung; Wong, Chris Kong-Chu; Chiu, Jill Man-Ying; Au, Doris Wai-Ting; Wong, Alice Sze-Tsai; Kong, Richard Yuen-Chong; Wu, Rudolf Shiu-Sun

    2016-01-01

    Hypoxia is amongst the most widespread and pressing problems in aquatic environments. Here we demonstrate that fish (Oryzias melastigma) exposed to hypoxia show reproductive impairments (retarded gonad development, decrease in sperm count and sperm motility) in F1 and F2 generations despite these progenies (and their germ cells) having never been exposed to hypoxia. We further show that the observed transgenerational reproductive impairments are associated with a differential methylation pattern of specific genes in sperm of both F0 and F2 coupled with relevant transcriptomic and proteomic alterations, which may impair spermatogenesis. The discovered transgenerational and epigenetic effects suggest that hypoxia might pose a dramatic and long-lasting threat to the sustainability of fish populations. Because the genes regulating spermatogenesis and epigenetic modifications are highly conserved among vertebrates, these results may also shed light on the potential transgenerational effects of hypoxia on other vertebrates, including humans. PMID:27373813

  13. Hypoxia-inducible factors as key regulators of tumor inflammation.

    PubMed

    Mamlouk, Soulafa; Wielockx, Ben

    2013-06-15

    Low levels of oxygen or hypoxia is often an obstacle in health, particularly in pathological disorders like cancer. The main family of transcription factors responsible for cell survival and adaptation under strenuous conditions of hypoxia are the "hypoxia-inducible factors" (HIFs). Together with prolyl hydroxylase domain enzymes (PHDs), HIFs regulates tumor angiogenesis, proliferation, invasion, metastasis, in addition to resistance to radiation and chemotherapy. Additionally, the entire HIF transcription cascade is involved in the "seventh" hallmark of cancer; inflammation. Studies have shown that hypoxia can influence tumor associated immune cells toward assisting in tumor proliferation, differentiation, vessel growth, distant metastasis and suppression of the immune response via cytokine expression alterations. These changes are not necessarily analogous to HIF's role in non-cancer immune responses, where hypoxia often encourages a strong inflammatory response. PMID:23055435

  14. The Role of Hypoxia Inducible Factor-1 in Hepatocellular Carcinoma

    PubMed Central

    Luo, Dongjun; Wang, Zhongxia; Wu, Junyi; Jiang, Chunping

    2014-01-01

    Hypoxia is a common feature of many solid tumors, including hepatocellular carcinoma (HCC). Hypoxia can promote tumor progression and induce radiation and chemotherapy resistance. As one of the major mediators of hypoxic response, hypoxia inducible factor-1 (HIF-1) has been shown to activate hypoxia-responsive genes, which are involved in multiple aspects of tumorigenesis and cancer progression, including proliferation, metabolism, angiogenesis, invasion, metastasis and therapy resistance. It has been demonstrated that a high level of HIF-1 in the HCC microenvironment leads to enhanced proliferation and survival of HCC cells. Accordingly, overexpression, of HIF-1 is associated with poor prognosis in HCC. In this review, we described the mechanism by which HIF-1 is regulated and how HIF-1 mediates the biological effects of hypoxia in tissues. We also summarized the latest findings concerning the role of HIF-1 in the development of HCC, which could shed light on new therapeutic approaches for the treatment of HCC. PMID:25101278

  15. HypoxamiRs: regulators of cardiac hypoxia and energy metabolism.

    PubMed

    Azzouzi, Hamid El; Leptidis, Stefanos; Doevendans, Pieter A; De Windt, Leon J

    2015-09-01

    Hypoxia and its intricate regulation are at the epicenter of cardiovascular research. Mediated by hypoxia-inducible factors as well as by several microRNAs, recently termed 'hypoxamiRs', hypoxia affects several cardiac pathophysiological processes. Hypoxia is the driving force behind the regulation of the characteristic metabolic switch from predominant fatty acid oxidation in the healthy heart to glucose utilization in the failing myocardium, but also instigates reactivation of the fetal gene program, induces the cardiac hypertrophy response, alters extracellular matrix composition, influences mitochondrial biogenesis, and impacts upon myocardial contractility. HypoxamiR regulation adds a new level of complexity to this multitude of hypoxia-mediated effects, rendering the understanding of the hypoxic response a fundamental piece in solving the cardiovascular disease puzzle. PMID:26197955

  16. Common responses of tumors and wounds to hypoxia.

    PubMed

    Payen, Valéry L; Brisson, Lucie; Dewhirst, Mark W; Sonveaux, Pierre

    2015-01-01

    Hypoxia is a characteristic of tumors and wounds. Hypoxic cells develop 2 common strategies to face hypoxia: the glycolytic switch and the angiogenic switch. At the onset of hypoxia, alleviation of the Pasteur effect ensures short-term cell survival. Long-term hypoxic cell survival requires a further acceleration of the glycolytic flux under the control of hypoxia-inducible factor 1 that stimulates the expression of most glycolytic transporters and enzymes, uncouples glycolysis from the TCA cycle, and rewires glycolysis to lactic fermentation. Hypoxic cells also trigger angiogenesis, a process that aims to restore normal microenvironmental conditions. Transcription factors (hypoxia-inducible factor 1, nuclear factor κB, activator protein 1) and lactate cooperate to stimulate the expression of proangiogenic agents. Cancer cells differ from normal hypoxic cells by their proliferative agenda and by a high metabolic heterogeneity. These effects in tumor account for further molecular and metabolic changes and for a persistent stimulation of angiogenesis. PMID:25815847

  17. Hypoxia: developments in basic science, physiology and clinical studies.

    PubMed

    Ward, D S; Karan, S B; Pandit, J J

    2011-12-01

    Airway management is primarily designed to avoid hypoxia, yet hypoxia remains the main ultimate cause of anaesthetic-related death and morbidity. Understanding some of the physiology of hypoxia is therefore essential as part of a 'holistic' approach to airway management. Furthermore, it is strategically important that national specialist societies dedicated to airway management do not only focus upon the technical aspects of airway management, but also embrace some of the relevant scientific questions. There has been a great deal of research into causation of hypoxia and the body's natural protective mechanisms and responses to it. This enables us to think of ways in which we might manipulate the cellular and molecular responses to confer greater protection against hypoxia-induced tissue injury. This article reviews some of those aspects. PMID:22074075

  18. PRDX2 and PRDX4 are negative regulators of hypoxia-inducible factors under conditions of prolonged hypoxia

    PubMed Central

    Luo, Weibo; Chen, Ivan; Chen, Yan; Alkam, Duah; Wang, Yingfei; Semenza, Gregg L.

    2016-01-01

    Hypoxia-inducible factors (HIFs) control the transcription of genes that are crucial for the pathogenesis of cancer and other human diseases. The transcriptional activity of HIFs is rapidly increased upon exposure to hypoxia, but expression of some HIF target genes decreases during prolonged hypoxia. However, the underlying mechanism for feedback inhibition is not completely understood. Here, we report that peroxiredoxin 2 (PRDX2) and PRDX4 interact with HIF-1α and HIF-2α in vitro and in hypoxic HeLa cells. Prolonged hypoxia increases the nuclear translocation of PRDX2 and PRDX4. As a result, PRDX2 and PRDX4 impair HIF-1 and HIF-2 binding to the hypoxia response elements of a subset of HIF target genes, thereby inhibiting gene transcription in cells exposed to prolonged hypoxia. PRDX2 and PRDX4 have no effect on the recruitment of p300 and RNA polymerase II to HIF target genes and the enzymatic activity of PRDX2 and PRDX4 is not required for inhibition of HIF-1 and HIF-2. We also demonstrate that PRDX2 is a direct HIF target gene and that PRDX2 expression is induced by prolonged hypoxia. These findings uncover a novel feedback mechanism for inhibition of HIF transcriptional activity under conditions of prolonged hypoxia. PMID:26837221

  19. Intrinsic ductility of glassy solids

    NASA Astrophysics Data System (ADS)

    Shi, Yunfeng; Luo, Jian; Yuan, Fenglin; Huang, Liping

    2014-01-01

    Glasses are usually brittle, seriously limiting their practical usage. Recently, the intrinsic ductility of glass was found to increase with the Poisson's ratio (v), with a sharp brittle-to-ductile (BTD) transition at vBTD = 0.31-0.32. Such a correlation between far-from-equilibrium fracture and near-equilibrium elasticity is unexpected and not understood. Molecular dynamics simulations, on three families of glasses (metallic glasses, amorphous silicon, and silica) with controlled bonding, processing, and testing conditions, show that glasses with low covalency and high structural disorder have high v and ductility, and vice versa. The BTD transitions triggered by the aforementioned causes in each system correspond to a unified vBTD value, which increases with its average coordination number (CN). The vBTD-CN relation can be comprehended by recognizing v as a measure of covalency and disorder, and the BTD transition as a competition between shear and cleavage. Our results provide guidelines for developing new recipes and processes for tough glasses.

  20. Intrinsic Localized Modes in Proteins

    PubMed Central

    Nicolaï, Adrien; Delarue, Patrice; Senet, Patrick

    2015-01-01

    Protein dynamics is essential for proteins to function. Here we predicted the existence of rare, large nonlinear excitations, termed intrinsic localized modes (ILMs), of the main chain of proteins based on all-atom molecular dynamics simulations of two fast-folder proteins and of a rigid α/β protein at 300 K and at 380 K in solution. These nonlinear excitations arise from the anharmonicity of the protein dynamics. The ILMs were detected by computing the Shannon entropy of the protein main-chain fluctuations. In the non-native state (significantly explored at 380 K), the probability of their excitation was increased by a factor between 9 and 28 for the fast-folder proteins and by a factor 2 for the rigid protein. This enhancement in the non-native state was due to glycine, as demonstrated by simulations in which glycine was mutated to alanine. These ILMs might play a functional role in the flexible regions of proteins and in proteins in a non-native state (i.e. misfolded or unfolded states). PMID:26658321

  1. Intelligent Viscoelastic Polyurethane Intrinsic Nanocomposites

    NASA Astrophysics Data System (ADS)

    Bilal Khan, M.

    2010-04-01

    Polyurethanes are multiphase systems comprising intrinsically variant nanodomains. The material properties can be tailored by adjusting the relative proportions and organizing the structure of the hard and soft segments akin to the spring-dashpot system in an automobile. This article describes how an intelligent polyurethane (PU) system is created to offer smart response to mechanical and vibration stimuli. In this work, unidirectional, dynamic mechanical thermal analysis (DMTA), acoustic, and impact testing results are qualified with the unique viscoelastic character that determines the rate-temperature response of the nanocomposite. Attenuated total reflection- infrared spectroscopy (ATR-IR) and DMTA offer a logical explanation of the observed viscoelastic behavior in terms of the nanodomains. Enhanced nanophase segregation between the polymer building blocks (hard and soft segments) is the primary mechanism that leads to a higher loss tangent peak in DMTA at a lower glass transition temperature ( T g ) for greater energy dissipation in the polymer matrix. Acoustic and impact attenuation are correlated with the mechanical modulus and loss tangent of the polymer. Finally, autodyne simulation reveals the unique shock absorbent behavior of the material layer when retrofitted to concrete structure. Typically, shock overpressure spikes of the order of 9.97 × 104 MPa experienced by the unprotected surface are entirely evened out at a lower overpressure threshold.

  2. Intrinsic Localized Modes in Proteins.

    PubMed

    Nicolaï, Adrien; Delarue, Patrice; Senet, Patrick

    2015-01-01

    Protein dynamics is essential for proteins to function. Here we predicted the existence of rare, large nonlinear excitations, termed intrinsic localized modes (ILMs), of the main chain of proteins based on all-atom molecular dynamics simulations of two fast-folder proteins and of a rigid α/β protein at 300 K and at 380 K in solution. These nonlinear excitations arise from the anharmonicity of the protein dynamics. The ILMs were detected by computing the Shannon entropy of the protein main-chain fluctuations. In the non-native state (significantly explored at 380 K), the probability of their excitation was increased by a factor between 9 and 28 for the fast-folder proteins and by a factor 2 for the rigid protein. This enhancement in the non-native state was due to glycine, as demonstrated by simulations in which glycine was mutated to alanine. These ILMs might play a functional role in the flexible regions of proteins and in proteins in a non-native state (i.e. misfolded or unfolded states). PMID:26658321

  3. Intrinsically photosensitive retinal ganglion cells.

    PubMed

    Do, Michael Tri Hoang; Yau, King-Wai

    2010-10-01

    Life on earth is subject to alternating cycles of day and night imposed by the rotation of the earth. Consequently, living things have evolved photodetective systems to synchronize their physiology and behavior with the external light-dark cycle. This form of photodetection is unlike the familiar "image vision," in that the basic information is light or darkness over time, independent of spatial patterns. "Nonimage" vision is probably far more ancient than image vision and is widespread in living species. For mammals, it has long been assumed that the photoreceptors for nonimage vision are also the textbook rods and cones. However, recent years have witnessed the discovery of a small population of retinal ganglion cells in the mammalian eye that express a unique visual pigment called melanopsin. These ganglion cells are intrinsically photosensitive and drive a variety of nonimage visual functions. In addition to being photoreceptors themselves, they also constitute the major conduit for rod and cone signals to the brain for nonimage visual functions such as circadian photoentrainment and the pupillary light reflex. Here we review what is known about these novel mammalian photoreceptors. PMID:20959623

  4. High expression of arachidonate 15-lipoxygenase and proinflammatory markers in human ischemic heart tissue

    SciTech Connect

    Magnusson, Lisa U.; Lundqvist, Annika; Asp, Julia; Synnergren, Jane; Johansson, Cecilia Thalen; Palmqvist, Lars; Jeppsson, Anders; Hulten, Lillemor Mattsson

    2012-07-27

    Highlights: Black-Right-Pointing-Pointer We found a 17-fold upregulation of ALOX15 in the ischemic heart. Black-Right-Pointing-Pointer Incubation of human muscle cells in hypoxia showed a 22-fold upregulation of ALOX15. Black-Right-Pointing-Pointer We observed increased levels of proinflammatory markers in ischemic heart tissue. Black-Right-Pointing-Pointer Suggesting a link between ischemia and inflammation in ischemic heart biopsies. -- Abstract: A common feature of the ischemic heart and atherosclerotic plaques is the presence of hypoxia (insufficient levels of oxygen in the tissue). Hypoxia has pronounced effects on almost every aspect of cell physiology, and the nuclear transcription factor hypoxia inducible factor-1{alpha} (HIF-1{alpha}) regulates adaptive responses to low concentrations of oxygen in mammalian cells. In our recent work, we observed that hypoxia increases the proinflammatory enzyme arachidonate 15-lipoxygenase (ALOX15B) in human carotid plaques. ALOX15 has recently been shown to be present in the human myocardium, but the effect of ischemia on its expression has not been investigated. Here we test the hypothesis that ischemia of the heart leads to increased expression of ALOX15, and found an almost 2-fold increase in HIF-1{alpha} mRNA expression and a 17-fold upregulation of ALOX15 mRNA expression in the ischemic heart biopsies from patients undergoing coronary bypass surgery compared with non ischemic heart tissue. To investigate the effect of low oxygen concentration on ALOX15 we incubated human vascular muscle cells in hypoxia and showed that expression of ALOX15 increased 22-fold compared with cells incubated in normoxic conditions. We also observed increased mRNA levels of proinflammatory markers in ischemic heart tissue compared with non-ischemic controls. In summary, we demonstrate increased ALOX15 in human ischemic heart biopsies. Furthermore we demonstrate that hypoxia increases ALOX15 in human muscle cells. Our results yield

  5. STAT3 is a key transcriptional regulator of cancer stem cell marker CD133 in HCC

    PubMed Central

    Ghoshal, Sarani; Fuchs, Bryan C.

    2016-01-01

    Cancer stem cell (CSC) marker CD133 was found to be upregulated in many cancers including hepatocellular carcinoma (HCC). However, the molecular mechanism of CD133 regulation in the liver tumor microenvironment has remained elusive. In this study Won and colleagues report that interleukin-6 (IL-6) mediated signal transducer and activator of transcription factor 3 (STAT3) signaling and hypoxia enhance the expression of CD133 and promote the progression of HCC. PMID:27275460

  6. Interdiffusion and Intrinsic Diffusion in the Mg-Al System

    SciTech Connect

    Brennan, Sarah; Bermudez, Katrina; Sohn, Yong Ho; Kulkarni, Nagraj S

    2012-01-01

    Solid-to-solid diffusion couples were assembled and annealed to examine the diffusion between pure Mg (99.96%) and Al (99.999%). Diffusion anneals were carried out at 300 , 350 , and 400 C for 720, 360, and 240 hours, respectively. Optical and scanning electron microscopes were utilized to identify the formation of the intermetallic phases, -Al12Mg17 and -Al3Mg2 and absence of the -phase in the diffusion couples. Thicknesses of the -Al12Mg17 and -Al3Mg2 phases were measured and the parabolic growth constants were calculated to determine the activation energies for the growth, 165 and 86 KJ/mole, respectively. Concentration profiles were determined with electron microprobe analysis using pure elemental standards. Composition-dependent interdiffusion coefficients in Mg-solid solution, -Al12Mg17 and - Al3Mg2 and Al-solid solutions were calculated based on the Boltzmann-Matano analysis. Average effective interdiffusion coefficients for each phase were also calculated, and the magnitude was the highest for the -Al3Mg2 phase, followed by -Al12Mg17, Al-solid solution and Mg-solid solution. Intrinsic diffusion coefficients based on Huemann s analysis (e.g., marker plane) were determined for the ~38 at.% Mg in the -Al3Mg2 phase. Activation energies and the pre-exponential factors for the inter- and intrinsic diffusion coefficients were calculated for the temperature range examined. The -Al3Mg2 phase was found to have the lowest activation energies for growth and interdiffusion among all four phases studied. At the marker location in the -Al3Mg2 phase, the intrinsic diffusion of Al was found to be faster than that of Mg. Extrapolations of the impurity diffusion coefficients in the terminal solid solutions were made and compared to the available self- and impurity diffusion data from literature. Thermodynamic factor, tracer diffusion coefficients and atomic mobilities at the marker plane composition were approximated using available literature values of Mg activity in the -Al

  7. News about VDAC1 in Hypoxia

    PubMed Central

    Mazure, N. M.

    2016-01-01

    The voltage-dependent anion channel (VDAC) is the main interface between the cytosol and mitochondria of cells. It plays a crucial role in both mitochondrial metabolism and cell death. The main basic function of this channel is to mediate and gate the flux of small ions, metabolites, and adenosine triphosphate. Changes in its structure, and thus conformation, are expected to affect its activity and modulate the ability of cancer cells to expand. In this review, we describe a novel mechanism by which mitochondria of cells in hypoxia, a low level of oxygen, protects from apoptosis. In hypoxia, some mitochondria become enlarged due to hyperfusion. These mitochondria possess a truncated form of VDAC1 (VDAC1-ΔC), which is linked to the higher metabolic capacity and the greater resistance to cell death of hypoxic cells. However, not all of the VDAC1 protein is truncated, but the amount of the full-length form is diminished compared to the amount in normoxic cells. First, we describe how such a decrease effects cell proliferation, respiration, glycolysis, and other processes. Second, we report on a novel mitochondrial-endolysosomal crosstalk that leads to VDAC1 truncation. By pharmacological targeting of VDAC1-ΔC, the production of energy could be turned off and the sensitivity to cell death restored. This could counteract the favorable microenvironment that gives cancer cells a growth advantage and thereby disrupts the balance between life and death, which is controlled by VDAC1. PMID:27625993

  8. Mechanisms of intermittent hypoxia induced hypertension

    PubMed Central

    Bosc, Laura V González; Resta, Thomas; Walker, Benjimen; Kanagy, Nancy L

    2010-01-01

    Abstract Exposing rodents to brief episodes of hypoxia mimics the hypoxemia and the cardiovascular and metabolic effects observed in patients with obstructive sleep apnoea (OSA), a condition that affects between 5% and 20% of the population. Apart from daytime sleepiness, OSA is associated with a high incidence of systemic and pulmonary hypertension, peripheral vascular disease, stroke and sudden cardiac death. The development of animal models to study sleep apnoea has provided convincing evidence that recurrent exposure to intermittent hypoxia (IH) has significant vascular and haemodynamic impact that explain much of the cardiovascular morbidity and mortality observed in patients with sleep apnoea. However, the molecular and cellular mechanisms of how IH causes these changes is unclear and under investigation. This review focuses on the most recent findings addressing these mechanisms. It includes a discussion of the contribution of the nervous system, circulating and vascular factors, inflammatory mediators and transcription factors to IH-induced cardiovascular disease. It also highlights the importance of reactive oxygen species as a primary mediator of the systemic and pulmonary hypertension that develops in response to exposure to IH. PMID:19818095

  9. Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) contains hypoxia response elements: relevance to lytic induction by hypoxia.

    PubMed

    Haque, Muzammel; Davis, David A; Wang, Victoria; Widmer, Isabelle; Yarchoan, Robert

    2003-06-01

    Kaposi's sarcoma (KS)-associated herpesvirus (KSHV), also known as human herpesvirus 8, is an etiologic agent of KS, primary effusion lymphoma (PEL), and multicentric Castleman's disease. We recently demonstrated that hypoxia can induce lytic replication of KSHV in PEL cell lines. Hypoxia induces the accumulation of hypoxia-inducible factors (HIF), and we hypothesized that the KSHV genome may respond to hypoxia through functional hypoxia response elements (HREs). Here, we demonstrate the presence of at least two promoters within the KSHV genome that are activated by hypoxia or hypoxia mimics. One is in the promoter region of the gene for Rta, the main lytic switch gene, and the other is within the promoter region of ORF34, a lytic gene of unknown function. The ORF34 promoter contains three putative consensus HREs oriented in the direction of the gene. Dissection and site-directed mutagenesis studies confirmed that one of the HREs of the ORF34 promoter is functional. Under conditions of hypoxia, the ORF34 promoter was strongly upregulated by HIF-1 alpha and HIF-2 alpha. By contrast, the promoter of the gene for Rta appeared to be preferentially upregulated by HIF-2 alpha. Reverse transcription-PCR analysis revealed that specific messages for ORF34 and ORF50 are upregulated in BCBL-1 cells exposed to hypoxia. An HIF-1 binding and competition assay demonstrated that the HRE sequence from the ORF34 promoter can compete for HIF-1 alpha binding to an erythropoietin HRE oligonucleotide while a mutant sequence cannot. Thus, we demonstrated that a viral gene can be activated by hypoxia through activation of a functional viral HRE. To our knowledge, this is the first example of a functional HRE in a viral promoter. PMID:12767996

  10. Intrinsic bioremediation of landfills interim report

    SciTech Connect

    Brigmon, R.L.; Fliermans, C.B.

    1997-07-14

    Intrinsic bioremediation is a risk management option that relies on natural biological and physical processes to contain the spread of contamination from a source. Evidence is presented in this report that intrinsic bioremediation is occurring at the Sanitary Landfill is fundamental to support incorportion into a Corrective Action Plan (CAP).

  11. Chronic intermittent hypoxia induces lung growth in adult mice

    PubMed Central

    Bevans-Fonti, Shannon; Grigoryev, Dmitry N.; Drager, Luciano F.; Myers, Allen C.; Wise, Robert A.; Schwartz, Alan R.; Mitzner, Wayne; Polotsky, Vsevolod Y.

    2011-01-01

    Obstructive sleep apnea (OSA) increases cardiovascular morbidity and mortality, which have been attributed to intermittent hypoxia (IH). The effects of IH on lung structure and function are unknown. We used a mouse model of chronic IH, which mimics the O2 profile in patients with OSA. We exposed adult C57BL/6J mice to 3 mo of IH with a fraction of inspired oxygen (FiO2) nadir of 5% 60 times/h during the 12-h light phase. Control mice were exposed to room air. Lung volumes were measured by quasistatic pressure-volume (PV) curves under anesthesia and by water displacement postmortem. Lungs were processed for morphometry, and the mean airspace chord length (Lm) and alveolar surface area were determined. Lung tissue was stained for markers of proliferation (proliferating cell nuclear antigen), apoptosis (terminal deoxynucleotidyl transferase dUTP nick-end labeling), and type II alveolar epithelial cells (surfactant protein C). Gene microarrays were performed, and results were validated by real-time PCR. IH increased lung volumes by both PV curves (air vs. IH, 1.16 vs. 1.44 ml, P < 0.0001) and water displacement (P < 0.01) without changes in Lm, suggesting that IH increased the alveolar surface area. IH induced a 60% increase in cellular proliferation, but the number of proliferating type II alveolocytes tripled. There was no increase in apoptosis. IH upregulated pathways of cellular movement and cellular growth and development, including key developmental genes vascular endothelial growth factor A and platelet-derived growth factor B. We conclude that IH increases alveolar surface area by stimulating lung growth in adult mice. PMID:21131398

  12. Separating Scattering from Intrinsic Attenuation

    NASA Astrophysics Data System (ADS)

    van Wijk, K.; Scales, J. A.

    2003-12-01

    The subsurface appears disordered at all length-scales. Therefore, wave propatation at seismic or ultrasonic frequencies is subject to complicated scatterings. A pulse propagating in the subsurface loses energy at each scattering off an impedance contrast, but also decreases in amplitude as the impulse interacts with fluids in the rock. We call the latter non-elastic effect "intrinsic Q", while the former is "scattering Q". It is often the fluids in the rocks that are of interest, but conventional reflection and transmission of the incident pulse only cannot deceipher the individual components of Q due to scattering and fluid movement in the pore-space. We present an approach that can unravel these two mechanisms, allowing a separate estimate of absorption. This method treats the propagation of the average intensity in the framework of radiative transfer (RT); the arrival of (what is left of) the incident pulse is modeled as the coherent energy, whereas the later arriving multiply scattered events form the incoherent intensity. The coherent pulse decays exponentially due to a combination of scattering and absorption, and so does the incoherent intensity. However, multiple scattering can re-direct energy back to the receiver, supplying a gain-term at later times that makes up the incoherent intensity. Strictly speaking, one can invert for scattering and absorption from the intensity at late times only, often modeled with the late-time equivalent of RT, diffusion. However, we will show that fitting both early- and late-time signal with RT constrains absorption and scattering constants more rigorously. These ideas are illustrated by laboratory and sonic-logging measurements.

  13. Transcriptome analysis of the plateau fish (Triplophysa dalaica): Implications for adaptation to hypoxia in fishes.

    PubMed

    Wang, Ying; Yang, Liandong; Wu, Bo; Song, Zhaobin; He, Shunping

    2015-07-10

    Triplophysa dalaica, endemic species of Qinghai-Tibetan Plateau, is informative for understanding the genetic basis of adaptation to hypoxic conditions of high altitude habitats. Here, a comprehensive gene repertoire for this plateau fish was generated using the Illumina deep paired-end high-throughput sequencing technology. De novo assembly yielded 145, 256 unigenes with an average length of 1632 bp. Blast searches against GenBank non-redundant database annotated 74,594 (51.4%) unigenes encoding for 30,047 gene descriptions in T. dalaica. Functional annotation and classification of assembled sequences were performed using Gene Ontology (GO), clusters of euKaryotic Orthologous Groups (KOG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. After comparison with other fish transcriptomes, including silver carp (Hypophthalmichthys molitrix) and mud loach (Misgurnus anguillicaudatus), 2621 high-quality orthologous gene alignments were constructed among these species. 61 (2.3%) of the genes were identified as having undergone positive selection in the T. dalaica lineage. Within the positively selected genes, 13 genes were involved in hypoxia response, of which 11 were listed in HypoxiaDB. Furthermore, duplicated hif-α (hif-1αA/B and hif-2αA/B), EGLN1 and PPARA candidate genes involved in adaptation to hypoxia were identified in T. dalaica transcriptome. Branch-site model in PAML validated that hif-1αB and hif-2αA genes have undergone positive selection in T.dalaica. Finally, 37,501 simple sequence repeats (SSRs) and 19,497 high-quality single nucleotide polymorphisms (SNPs) were identified in T. dalaica. The identified SSR and SNP markers will facilitate the genetic structure, population geography and ecological studies of Triplophysa fishes. PMID:25869933

  14. Cellular memory of hypoxia elicits neuroblastoma metastasis and enables invasion by non-aggressive neighbouring cells.

    PubMed

    Herrmann, A; Rice, M; Lévy, R; Pizer, B L; Losty, P D; Moss, D; Sée, V

    2015-01-01

    Therapies targeting cancer metastasis are challenging owing to the complexity of the metastatic process and the high number of effectors involved. Although tumour hypoxia has previously been associated with increased aggressiveness as well as resistance to radio- and chemotherapy, the understanding of a direct link between the level and duration of hypoxia and the individual steps involved in metastasis is still missing. Using live imaging in a chick embryo model, we have demonstrated that the exposure of neuroblastoma cells to 1% oxygen for 3 days was capable of (1) enabling cell migration towards blood vessels, (2) slowing down their velocity within blood vessels to facilitate extravasation and (3) promoting cell proliferation in primary and secondary sites. We have shown that cells do not have to be hypoxic anymore to exhibit these acquired capabilities as a long-term memory of prior hypoxic exposure is kept. Furthermore, non-hypoxic cells can be influenced by neighbouring hypoxic preconditioned cells and be entrained in the metastatic progression. The acquired aggressive phenotype relies on hypoxia-inducible factor (HIF)-dependent transcription of a number of genes involved in metastasis and can be impaired by HIF inhibition. Altogether, our results demonstrate the need to consider both temporal and spatial tumour heterogeneity because cells can 'remember' an earlier environment and share their acquired phenotype with their close neighbours. As a consequence, it is necessary to monitor the correct hypoxic markers to be able to predict the consequences of the cells' history on their behaviour and their potential response to therapies. PMID:25664931

  15. Phase I study of evofosfamide, an investigational hypoxia-activated prodrug, in patients with advanced leukemia.

    PubMed

    Badar, Talha; Handisides, Damian R; Benito, Juliana M; Richie, Mary Ann; Borthakur, Gautam; Jabbour, Elias; Harutyunyan, Karine; Konoplev, Sergej; Faderl, Stefan; Kroll, Stew; Andreeff, Michael; Pearce, Tillman; Kantarjian, Hagop M; Cortes, Jorge E; Thomas, Deborah A; Konopleva, Marina

    2016-08-01

    Tumor hypoxia causes resistance to radiation and chemotherapy. Evofosfamide (TH-302) has exhibited specific hypoxia-dependent cytotoxicity against primary acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) samples in vitro. Based on these findings, a Phase I study of evofosfamide was designed for patients with relapsed/refractory leukemia (NCT01149915). In this open-label study, patients were treated with evofosfamide as a 30-60 min/day infusion on Days 1-5 of a 21-day cycle (Arm A, n = 38) or as a continuous infusion over 120 hr over Days 1-5 of a 21-day cycle (Arm B, n = 11). Forty-nine patients were treated including 39 (80%) with AML and 9 (18%) with ALL. Patients had received a median of five prior therapies. In Arm A, the dose-limiting toxicities (DLTs) were grade 3 esophagitis, observed at a dose of 550 mg/m(2) . The maximum tolerated dose (MTD) was a daily dose of 460 mg/m(2) . In Arm B, the DLTs were grade 3 stomatitis and hyperbilirubinemia, observed at a daily dose of 460 mg/m(2) . The continuous infusion MTD was a daily dose of 330 mg/m(2) . Hypoxia markers HIF-1α and CAIX were highly expressed in leukemic bone marrow and were significantly reduced after evofosfamide therapy. The combined overall response rate in Arms A and B was 6% (2 CR/CRi and 1 PR), with all responses seen in Arm A. Evofosfamide has shown limited activity in heavily pretreated leukemia patients. Further evaluation investigating evofosfamide in combination with cytotoxic or demethylating agents is warranted. Am. J. Hematol. 91:800-805, 2016. © 2016 Wiley Periodicals, Inc. PMID:27169385

  16. Tirapazamine-induced cytotoxicity and DNA damage in transplanted tumors: relationship to tumor hypoxia.

    PubMed

    Siim, B G; Menke, D R; Dorie, M J; Brown, J M

    1997-07-15

    Tirapazamine (TPZ) is a hypoxia-selective bioreductive drug currently in Phases II and III clinical trials with both radiotherapy and chemotherapy. The response of tumors to TPZ is expected to depend both on the levels of reductive enzymes that activate the drug to a DNA-damaging and toxic species and on tumor oxygenation. Both of these parameters are likely to vary between individual tumors. In this study, we examined whether the enhancement of radiation damage to tumors by TPZ can be predicted from TPZ-induced DNA damage measured using the comet assay. DNA damage provides a functional end point that is directly related to cell killing and should be dependent on both reductive enzyme activity and hypoxia. We demonstrate that TPZ potentiates tumor cell kill by fractionated radiation in three murine tumors (SCCVII, RIF-1, and EMT6) and two human tumor xenografts (A549 and HT29), with no potentiation observed in a third xenograft (HT1080). Overall, there was no correlation of radiation potentiation and TPZ-induced DNA damage in the tumors, except that the nonresponsive tumor xenograft had significantly lower levels of DNA damage than the other five tumor types. However, there was a large tumor-to-tumor variability in DNA damage within each tumor type. This variability appeared not to result from differences in activity of the reductive enzymes but largely from differences in oxygenation between individual tumors, measured using fluorescent detection of the hypoxia marker EF5. The results, therefore, suggest that the sensitivity of individual tumors to TPZ, although not necessarily the response to TPZ plus radiation, might be assessed from measurements of DNA damage using the comet assay. PMID:9230202

  17. Glycolysis determines dichotomous regulation of T cell subsets in hypoxia.

    PubMed

    Xu, Yang; Chaudhury, Arindam; Zhang, Ming; Savoldo, Barbara; Metelitsa, Leonid S; Rodgers, John; Yustein, Jason T; Neilson, Joel R; Dotti, Gianpietro

    2016-07-01

    Hypoxia occurs in many pathological conditions, including chronic inflammation and tumors, and is considered to be an inhibitor of T cell function. However, robust T cell responses occur at many hypoxic inflammatory sites, suggesting that functions of some subsets are stimulated under low oxygen conditions. Here, we investigated how hypoxic conditions influence human T cell functions and found that, in contrast to naive and central memory T cells (TN and TCM), hypoxia enhances the proliferation, viability, and cytotoxic action of effector memory T cells (TEM). Enhanced TEM expansion in hypoxia corresponded to high hypoxia-inducible factor 1α (HIF1α) expression and glycolytic activity compared with that observed in TN and TCM. We determined that the glycolytic enzyme GAPDH negatively regulates HIF1A expression by binding to adenylate-uridylate-rich elements in the 3'-UTR region of HIF1A mRNA in glycolytically inactive TN and TCM. Conversely, active glycolysis with decreased GAPDH availability in TEM resulted in elevated HIF1α expression. Furthermore, GAPDH overexpression reduced HIF1α expression and impaired proliferation and survival of T cells in hypoxia, indicating that high glycolytic metabolism drives increases in HIF1α to enhance TEM function during hypoxia. This work demonstrates that glycolytic metabolism regulates the translation of HIF1A to determine T cell responses to hypoxia and implicates GAPDH as a potential mechanism for controlling T cell function in peripheral tissue. PMID:27294526

  18. Role of hypoxia and vascular endothelial growth factors in lymphangiogenesis

    PubMed Central

    Morfoisse, Florent; Renaud, Edith; Hantelys, Fransky; Prats, Anne-Catherine; Garmy-Susini, Barbara

    2014-01-01

    Hypoxia is known to be a major factor in the induction of angiogenesis during tumor development but its role in lymphangiogenesis remains unclear. Blood and lymphatic vasculatures are stimulated by the vascular endothelial family of growth factors – the VEGFs. In this review, we investigate the role of hypoxia in the molecular regulation of synthesis of the lymphangiogenic growth factors VEGF-A, VEGF-C, and VEGF-D. Gene expression can be regulated by hypoxia at either transcriptional or translational levels. In contrast to strong induction of DNA transcription by hypoxia-inducible factors (HIFs), the majority of cellular stresses such as hypoxia lead to inhibition of cap-dependent translation of mRNA and downregulation of protein synthesis. Here, we describe how initiation of translation of VEGF mRNA is induced by hypoxia through an internal ribosome entry site (IRES)-dependent mechanism. Considering the implications of the lymphatic vasculature for metastatic dissemination, it is crucial to understand the molecular regulation of lymphangiogenic growth factors by hypoxia to obtain new insights into cancer therapy. PMID:27308316

  19. Role of hypoxia and vascular endothelial growth factors in lymphangiogenesis

    PubMed Central

    Morfoisse, Florent; Renaud, Edith; Hantelys, Fransky; Prats, Anne-Catherine; Garmy-Susini, Barbara

    2015-01-01

    Hypoxia is a major condition for the induction of angiogenesis during tumor development but its role in lymphangiogenesis remains unclear. Blood and lymphatic vasculatures are stimulated by growth factors from the vascular endothelial family: the VEGFs. In this review, we investigate the role of hypoxia in the molecular regulation of synthesis of lymphangiogenic growth factors VEGF-A, VEGF-C, and VEGF-D. Gene expression can be regulated at transcriptional and translational levels by hypoxia. Despite strong regulation of DNA transcription induced by hypoxia-inducible factors (HIFs), the majority of cellular stresses such as hypoxia lead to inhibition of cap-dependent translation of the mRNA, resulting in downregulation of protein synthesis. Here, we describe how translation initiation of VEGF mRNAs is induced by hypoxia through an internal ribosome entry site (IRES)-dependent mechanism. Considering the implication of the lymphatic vasculature in metastatic dissemination, it seems crucial to understand the hypoxia-induced molecular regulation of lymphangiogenic growth factors to obtain new insights for cancer therapy. PMID:27308508

  20. Thermoneutrality modifies the impact of hypoxia on lipid metabolism.

    PubMed

    Jun, Jonathan C; Shin, Mi-Kyung; Yao, Qiaoling; Devera, Ronald; Fonti-Bevans, Shannon; Polotsky, Vsevolod Y

    2013-02-15

    Hypoxia has been shown to rapidly increase triglycerides in mice by decreasing plasma lipoprotein clearance. However, the usual temperature of hypoxic exposure is below thermoneutrality for mice, which may increase thermogenesis and energy requirements, resulting in higher tissue lipid uptake. We hypothesize that decreased lipid clearance and ensuing hyperlipidemia are caused by hypoxic suppression of metabolism at cold temperatures and, therefore, would not occur at thermoneutrality. Twelve-week-old, male C57BL6/J mice were exposed to 6 h of 10% O₂ at the usual temperature (22°C) or thermoneutrality (30°C). Acclimation to 22°C increased lipid uptake in the heart, lungs, and brown adipose tissue, resulting in lower plasma triglyceride and cholesterol levels. At this temperature, hypoxia attenuated lipid uptake in most tissues, thereby raising plasma triglycerides and LDL cholesterol. Thermoneutrality decreased tissue lipid uptake, and hypoxia did not cause a further reduction in lipid uptake in any organs. Consequently, hypoxia at thermoneutrality did not affect plasma triglyceride levels. Unexpectedly, plasma HDL cholesterol increased. The effect of hypoxia on white adipose tissue lipolysis was also modified by temperature. Independent of temperature, hypoxia increased heart rate and glucose and decreased activity, body temperature, and glucose sensitivity. Our study underscores the importance of ambient temperature for hypoxia research, especially in studies of lipid metabolism. PMID:23249698

  1. Snail1 Mediates Hypoxia-Induced Melanoma Progression

    PubMed Central

    Liu, Shujing; Kumar, Suresh M.; Martin, James S.; Yang, Ruifeng; Xu, Xiaowei

    2011-01-01

    Tumor hypoxia is a known adverse prognostic factor, and the hypoxic dermal microenvironment participates in melanomagenesis. High levels of hypoxia inducible factor (HIF) expression in melanoma cells, particularly HIF-2α, is associated with poor prognosis. The mechanism underlying the effect of hypoxia on melanoma progression, however, is not fully understood. We report evidence that the effects of hypoxia on melanoma cells are mediated through activation of Snail1. Hypoxia increased melanoma cell migration and drug resistance, and these changes were accompanied by increased Snail1 and decreased E-cadherin expression. Snail1 expression was regulated by HIF-2α in melanoma. Snail1 overexpression led to more aggressive tumor phenotypes and features associated with stem-like melanoma cells in vitro and increased metastatic capacity in vivo. In addition, we found that knockdown of endogenous Snail1 reduced melanoma proliferation and migratory capacity. Snail1 knockdown also prevented melanoma metastasis in vivo. In summary, hypoxia up-regulates Snail1 expression and leads to increased metastatic capacity and drug resistance in melanoma cells. Our findings support that the effects of hypoxia on melanoma are mediated through Snail1 gene activation and suggest that Snail1 is a potential therapeutic target for the treatment of melanoma. PMID:21996677

  2. Hypoxia-induced alterations of G2 checkpoint regulators.

    PubMed

    Hasvold, Grete; Lund-Andersen, Christin; Lando, Malin; Patzke, Sebastian; Hauge, Sissel; Suo, ZhenHe; Lyng, Heidi; Syljuåsen, Randi G

    2016-05-01

    Hypoxia promotes an aggressive tumor phenotype with increased genomic instability, partially due to downregulation of DNA repair pathways. However, genome stability is also surveilled by cell cycle checkpoints. An important issue is therefore whether hypoxia also can influence the DNA damage-induced cell cycle checkpoints. Here, we show that hypoxia (24 h 0.2% O2) alters the expression of several G2 checkpoint regulators, as examined by microarray gene expression analysis and immunoblotting of U2OS cells. While some of the changes reflected hypoxia-induced inhibition of cell cycle progression, the levels of several G2 checkpoint regulators, in particular Cyclin B, were reduced in G2 phase cells after hypoxic exposure, as shown by flow cytometric barcoding analysis of individual cells. These effects were accompanied by decreased phosphorylation of a Cyclin dependent kinase (CDK) target in G2 phase cells after hypoxia, suggesting decreased CDK activity. Furthermore, cells pre-exposed to hypoxia showed increased G2 checkpoint arrest upon treatment with ionizing radiation. Similar results were found following other hypoxic conditions (∼0.03% O2 20 h and 0.2% O2 72 h). These results demonstrate that the DNA damage-induced G2 checkpoint can be altered as a consequence of hypoxia, and we propose that such alterations may influence the genome stability of hypoxic tumors. PMID:26791779

  3. Resveratrol attenuates hypoxia-induced neurotoxicity through inhibiting microglial activation.

    PubMed

    Zhang, Qun; Yuan, Lin; Zhang, Qingrui; Gao, Yan; Liu, Guangheng; Xiu, Meng; Wei, Xiang; Wang, Zhen; Liu, Dexiang

    2015-09-01

    Resveratrol is a natural polyphenol enriched in Polygonum cuspidatum and has been found to afford neuroprotective effects against neuroinflammation in the brain. Activated microglia can secrete various pro-inflammatory cytokines and neurotoxic mediators, which may contribute to hypoxic brain injuries. The aim of this study is to investigate the potential role of resveratrol in attenuating hypoxia-induced neurotoxicity via its anti-inflammatory actions through in vitro models of the BV-2 microglial cell line and primary microglia. We found that resveratrol significantly inhibited hypoxia-induced microglial activation and reduced subsequent release of pro-inflammatory factors. In addition, resveratrol inhibited the hypoxia-induced degradation of IκB-alpha and phosphorylation of p65 NF-κB protein. Hypoxia-induced ERK1/2 and JNK phosphorylation was also strongly inhibited by resveratrol, whereas resveratrol had no effect on hypoxia-stimulated p38 MAPK phosphorylation. Importantly, treating primary cortical neurons with conditioned medium (CM) from hypoxia-stimulated microglia induced neuronal apoptosis, which was reversed by CM co-treated with resveratrol. Taken together, resveratrol exerts neuroprotection against hypoxia-induced neurotoxicity through its anti-inflammatory effects in microglia. These effects were mediated, at least in part, by suppressing the activation of NF-ĸB, ERK and JNK MAPK signaling pathways. PMID:26225925

  4. Melatonin modulates the fetal cardiovascular defense response to acute hypoxia.

    PubMed

    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. PMID:25908097

  5. Role of nitric oxide in cardiovascular adaptation to intermittent hypoxia.

    PubMed

    Manukhina, Eugenia B; Downey, H Fred; Mallet, Robert T

    2006-04-01

    Hypoxia is one of the most frequently encountered stresses in health and disease. The duration, frequency, and severity of hypoxic episodes are critical factors determining whether hypoxia is beneficial or harmful. Adaptation to intermittent hypoxia has been demonstrated to confer cardiovascular protection against more severe and sustained hypoxia, and, moreover, to protect against other stresses, including ischemia. Thus, the direct and cross protective effects of adaptation to intermittent hypoxia have been used for treatment and prevention of a variety of diseases and to increase efficiency of exercise training. Evidence is mounting that nitric oxide (NO) plays a central role in these adaptive mechanisms. NO-dependent protective mechanisms activated by intermittent hypoxia include stimulation of NO synthesis as well as restriction of NO overproduction. In addition, alternative, nonenzymic sources of NO and negative feedback of NO synthesis are important factors in optimizing NO concentrations. The adaptive enhancement of NO synthesis and/or availability activates or increases expression of other protective factors, including heat shock proteins, antioxidants and prostaglandins, making the protection more robust and sustained. Understanding the role of NO in mechanisms of adaptation to hypoxia will support development of therapies to prevent and treat hypoxic or ischemic damage to organs and cells and to increase adaptive capabilities of the organism. PMID:16565431

  6. Evolutionary Genetics of Hypoxia Tolerance in Cetaceans during Diving

    PubMed Central

    Tian, Ran; Wang, Zhengfei; Niu, Xu; Zhou, Kaiya; Xu, Shixia; Yang, Guang

    2016-01-01

    Hypoxia was a major challenge faced by cetaceans during the course of secondary aquatic adaptation. Although physiological traits of hypoxia tolerance in cetaceans have been well characterized, the underlying molecular mechanisms remain unknown. We investigated the sequences of 17 hypoxia-tolerance-related genes in representative cetaceans to provide a comprehensive insight into the genetic basis of hypoxia tolerance in these animals. Genes involved in carrying and transporting oxygen in the blood and muscle (hemoglobin-α and β, myoglobin), and genes involved in the regulation of vasoconstriction (endothelin-1, -2, and -3; endothelin receptor type A and B; adrenergic receptor α-1D; and arginine vasopressin) appear to have undergone adaptive evolution, evidence for positive selection on their particular sites, and radical physiochemical property changes of selected condons. Interestingly, “long-diving” cetaceans had relatively higher ω (dN/dS) values than “short-diving” cetaceans for the hemoglobin β gene, indicating divergent selective pressure presented in cetacean lineages with different diving abilities. Additionally, parallel positive selection or amino acid changes (ADRA1D: P50A, A53G, AVPR1B: I/V270T) among animals exposed to different hypoxia habitats reflect functional convergence or similar genetic mechanisms of hypoxia tolerance. In summary, positive selection, divergent selective pressures, and parallel evolution at the molecular level provided some new insights into the genetic adaptation of hypoxia tolerance. PMID:26912402

  7. Thermoneutrality modifies the impact of hypoxia on lipid metabolism

    PubMed Central

    Shin, Mi-Kyung; Yao, Qiaoling; Devera, Ronald; Fonti-Bevans, Shannon; Polotsky, Vsevolod Y.

    2013-01-01

    Hypoxia has been shown to rapidly increase triglycerides in mice by decreasing plasma lipoprotein clearance. However, the usual temperature of hypoxic exposure is below thermoneutrality for mice, which may increase thermogenesis and energy requirements, resulting in higher tissue lipid uptake. We hypothesize that decreased lipid clearance and ensuing hyperlipidemia are caused by hypoxic suppression of metabolism at cold temperatures and, therefore, would not occur at thermoneutrality. Twelve-week-old, male C57BL6/J mice were exposed to 6 h of 10% O2 at the usual temperature (22°C) or thermoneutrality (30°C). Acclimation to 22°C increased lipid uptake in the heart, lungs, and brown adipose tissue, resulting in lower plasma triglyceride and cholesterol levels. At this temperature, hypoxia attenuated lipid uptake in most tissues, thereby raising plasma triglycerides and LDL cholesterol. Thermoneutrality decreased tissue lipid uptake, and hypoxia did not cause a further reduction in lipid uptake in any organs. Consequently, hypoxia at thermoneutrality did not affect plasma triglyceride levels. Unexpectedly, plasma HDL cholesterol increased. The effect of hypoxia on white adipose tissue lipolysis was also modified by temperature. Independent of temperature, hypoxia increased heart rate and glucose and decreased activity, body temperature, and glucose sensitivity. Our study underscores the importance of ambient temperature for hypoxia research, especially in studies of lipid metabolism. PMID:23249698

  8. Melatonin modulates the fetal cardiovascular defense response to acute hypoxia

    PubMed Central

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

    2015-01-01

    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. PMID:25908097

  9. Role of hypoxia and vascular endothelial growth factors in lymphangiogenesis.

    PubMed

    Morfoisse, Florent; Renaud, Edith; Hantelys, Fransky; Prats, Anne-Catherine; Garmy-Susini, Barbara

    2015-01-01

    Hypoxia is a major condition for the induction of angiogenesis during tumor development but its role in lymphangiogenesis remains unclear. Blood and lymphatic vasculatures are stimulated by growth factors from the vascular endothelial family: the VEGFs. In this review, we investigate the role of hypoxia in the molecular regulation of synthesis of lymphangiogenic growth factors VEGF-A, VEGF-C, and VEGF-D. Gene expression can be regulated at transcriptional and translational levels by hypoxia. Despite strong regulation of DNA transcription induced by hypoxia-inducible factors (HIFs), the majority of cellular stresses such as hypoxia lead to inhibition of cap-dependent translation of the mRNA, resulting in downregulation of protein synthesis. Here, we describe how translation initiation of VEGF mRNAs is induced by hypoxia through an internal ribosome entry site (IRES)-dependent mechanism. Considering the implication of the lymphatic vasculature in metastatic dissemination, it seems crucial to understand the hypoxia-induced molecular regulation of lymphangiogenic growth factors to obtain new insights for cancer therapy. PMID:27308508

  10. Evolutionary Genetics of Hypoxia Tolerance in Cetaceans during Diving.

    PubMed

    Tian, Ran; Wang, Zhengfei; Niu, Xu; Zhou, Kaiya; Xu, Shixia; Yang, Guang

    2016-03-01

    Hypoxia was a major challenge faced by cetaceans during the course of secondary aquatic adaptation. Although physiological traits of hypoxia tolerance in cetaceans have been well characterized, the underlying molecular mechanisms remain unknown. We investigated the sequences of 17 hypoxia-tolerance-related genes in representative cetaceans to provide a comprehensive insight into the genetic basis of hypoxia tolerance in these animals. Genes involved in carrying and transporting oxygen in the blood and muscle (hemoglobin-α and β, myoglobin), and genes involved in the regulation of vasoconstriction (endothelin-1, -2, and -3; endothelin receptor type A and B; adrenergic receptor α-1D; and arginine vasopressin) appear to have undergone adaptive evolution, evidence for positive selection on their particular sites, and radical physiochemical property changes of selected condons. Interestingly, "long-diving" cetaceans had relatively higher ω (dN/dS) values than "short-diving" cetaceans for the hemoglobin β gene, indicating divergent selective pressure presented in cetacean lineages with different diving abilities. Additionally, parallel positive selection or amino acid changes (ADRA1D: P50A, A53G,AVPR1B: I/V270T) among animals exposed to different hypoxia habitats reflect functional convergence or similar genetic mechanisms of hypoxia tolerance. In summary, positive selection, divergent selective pressures, and parallel evolution at the molecular level provided some new insights into the genetic adaptation of hypoxia tolerance. PMID:26912402

  11. Ventilatory adaptation to hypoxia occurs in serotonin-depleted rats.

    PubMed

    Olson, E B

    1987-08-01

    To test the hypothesis that serotonin mediated respiratory activity is involved in ventilatory adaptation to hypoxia, rats were treated with parachlorophenylalanine (PCPA), a potent, long-acting inhibitor of tryptophan hydroxylase, the rate-limiting enzyme in the biosynthesis of serotonin. In normoxia, a single, intraperitoneal injection of 300 mg PCPA/kg body weight decreased the Paco2 from a control level at 39.1 +/- 0.6 Torr (mean +/- 95% confidence limits) to 34.0 +/- 0.6 Torr measured during a period from 1 to 48 h following PCPA treatment. This PCPA-produced hyperventilation corresponds to an increase of 3.7 +/- 0.5 in the VA (BTPS)/Vco2 (STPD) ratio. Hyperventilation during ventilatory adaptation to hypoxia (PIO2 approximately equal to 90 Torr) was superimposed in an additive fashion on the underlying hyperventilation due to PCPA pretreatment. Specifically, PCPA pretreatment caused an average 3.5 +/- 1.2 increase in the VA/VCO2 ratio determined in acute (1 h) hypoxia, chronic (24 h) hypoxia and acute return to normoxia following chronic hypoxia. Since ventilatory adaptation to hypoxia occurred in rats treated with PCPA, the prolonged, serotonin mediated respiratory activity described by Millhorn et al. (1980b) is probably not important in ventilatory acclimatization to - or deacclimatization from - hypoxia. PMID:2957766

  12. Regulation of CREB by moderate hypoxia in PC12 cells.

    PubMed

    Beitner-Johnson, D; Rust, R T; Hsieh, T; Millhorn, D E

    2000-01-01

    The mechanisms by which excitable cells adapt and respond to changes in O2 levels remain largely unknown. We have investigated the effect of hypoxia on the cyclic AMP response element binding protein (CREB) transcription factor. PC12 cells were exposed to moderate levels of hypoxia (5% O2) for various times between 20 min and 6 hr. We found that hypoxia rapidly and persistently induced ser133 phosphorylation of CREB. This effect was more robust than that produced by exposing PC12 cells to either forskolin, KCl, or NGF. This effect was not due to activation of any of the previously known CREB kinases, including PKA, CaMK, PKC, p70s6k, or MAPKAP kinase-2. Thus, hypoxia may induce activation of a novel CREB kinase. To test whether phosphorylation of CREB was associated with an activation of CRE-dependent gene expression, cells were transfected with wild type and mutated regions of the 5'-flanking region of the tyrosine hydroxylase (TH) gene fused to a CAT reporter gene. Mutation of the CRE element in a TH reporter gene reduced, but did not abolish, the effects of hypoxia on TH gene expression. However, hypoxia did not induce transactivation of a GAL4-luciferase reporter by a GAL4-CREB fusion protein. Thus, the mechanism by which hypoxia regulates CREB is distinct, and more complex, than that induced by forskolin, depolarization, or nerve growth factor. PMID:10849656

  13. Amelioration of ER stress by 4-phenylbutyric acid reduces chronic hypoxia induced cardiac damage and improves hypoxic tolerance through upregulation of HIF-1α.

    PubMed

    Jain, Kanika; Suryakumar, Geetha; Ganju, Lilly; Singh, Shashi Bala

    2016-08-01

    While endoplasmic reticulum (ER) stress has been observed in several human diseases, few studies have reported the involvement of ER stress in chronic hypoxia (CH) induced cardiac damage. Hypoxia, such as that prevalent at high altitude (HA), forms the underlying cause of several maladies including cardiovascular diseases. While the role of hypoxia inducible factor-1 (HIF-1α) in the adaptive responses to hypoxia is known, the role of the unfolded protein response (UPR) is only recently being explored in the HA pathophysiologies. The present study investigates the effect of ER stress modulation on CH mediated injury and the cardioprotective action of 4-phenylbutyric acid (PBA) in enhancing survival response under hypoxia. Here, we observed that exposure of rats, for 1, 7 and 14days CH to a simulated altitude of 7620m, led to cardiac hypertrophy and significant protein oxidation. This induced the activation of UPR signaling mechanisms, mediated by PERK, IRE1α and ATF6. By 14days, there was a marked upregulation of apoptosis, evident in increased CHOP and caspase-3/9 activity. PBA reduced CH induced right ventricular enlargement and apoptosis. Further, in contrast to tunicamycin, PBA considerably enhanced hypoxic tolerance. An elevation in the level of antioxidant enzymes, HIF-1α and its regulated proteins (HO-1, GLUT-1) was observed in the PBA administered animals, along with a concomitant suppression of UPR markers. Our study thus emphasizes upon the attenuation of ER stress by PBA as a mechanism to diminish CH induced cardiac injury and boost hypoxic survival, providing an insight into the novel relationship between the HIF-1α and UPR under hypoxia. PMID:27058435

  14. Cardiac responses to hypoxia and reoxygenation in Drosophila.

    PubMed

    Zarndt, Rachel; Piloto, Sarah; Powell, Frank L; Haddad, Gabriel G; Bodmer, Rolf; Ocorr, Karen

    2015-12-01

    An adequate supply of oxygen is important for the survival of all tissues, but it is especially critical for tissues with high-energy demands, such as the heart. Insufficient tissue oxygenation occurs under a variety of conditions, including high altitude, embryonic and fetal development, inflammation, and thrombotic diseases, often affecting multiple organ systems. Responses and adaptations of the heart to hypoxia are of particular relevance in human cardiovascular and pulmonary diseases, in which the effects of hypoxic exposure can range in severity from transient to long-lasting. This study uses the genetic model system Drosophila to investigate cardiac responses to acute (30 min), sustained (18 h), and chronic (3 wk) hypoxia with reoxygenation. Whereas hearts from wild-type flies recovered quickly after acute hypoxia, exposure to sustained or chronic hypoxia significantly compromised heart function upon reoxygenation. Hearts from flies with mutations in sima, the Drosophila homolog of the hypoxia-inducible factor alpha subunit (HIF-α), exhibited exaggerated reductions in cardiac output in response to hypoxia. Heart function in hypoxia-selected flies, selected over many generations for survival in a low-oxygen environment, revealed reduced cardiac output in terms of decreased heart rate and fractional shortening compared with their normoxia controls. Hypoxia-selected flies also had smaller hearts, myofibrillar disorganization, and increased extracellular collagen deposition, consistent with the observed reductions in contractility. This study indicates that longer-duration hypoxic insults exert deleterious effects on heart function that are mediated, in part, by sima and advances Drosophila models for the genetic analysis of cardiac-specific responses to hypoxia and reoxygenation. PMID:26377557

  15. An Exploratory Study Into the Role of Dynamic Contrast-Enhanced Magnetic Resonance Imaging or Perfusion Computed Tomography for Detection of Intratumoral Hypoxia in Head-and-Neck Cancer

    SciTech Connect

    Newbold, Kate Castellano, Isabel; Charles-Edwards, Elizabeth; Mears, Dorothy; Sohaib, Aslam; Leach, Martin; Rhys-Evans, Peter; Clarke, Peter; Fisher, Cyril; Harrington, Kevin; Nutting, Christopher

    2009-05-01

    Purpose: Hypoxia in patients with head-and-neck cancer (HNC) is well established and known to cause radiation resistance and treatment failure in the management of HNC. This study examines the role of parameters derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and perfusion computed tomography (CT) as surrogate markers of intratumoral hypoxia, defined by using the exogenous marker of hypoxia pimonidazole and the endogenous marker carbonic anhydrase 9 (CA9). Methods and Materials: Patients with HNC underwent preoperative DCE-MRI, perfusion CT, and pimonidazole infusion. Imaging parameters were correlated with pimonidazole and CA9 staining. The strength of correlations was tested by using a two-tailed Spearman's rank correlation coefficient. Results: Twenty-three regions of interest were analyzed from the 7 patients who completed the DCE-MRI studies. A number of statistically significant correlations were seen between DCE-MRI parameters (volume transfer between blood plasma and extracellular extravascular space [EES], volume of EES, rate constant between EES and blood plasma, time at arrival of contrast inflow, time to peak, average gradient, and time to onset) and areas with a pimonidazole score of 4. In the case of CA9 staining, only a weak correlation was shown with wash-in rate. There were no significant correlations between perfusion CT parameters and pimonidazole staining or CA9 expression. Conclusion: Intratumoral hypoxia in patients with HNC may be predicted by using DCE-MRI; however, perfusion CT requires further investigation.

  16. Hypoxia-Inducible Factor-1α and CD271 inversely correlate with melanoma invasiveness.

    PubMed

    Marconi, Alessandra; Borroni, Riccardo G; Truzzi, Francesca; Longo, Caterina; Pistoni, Federica; Pellacani, Giovanni; Pincelli, Carlo

    2015-05-01

    Melanoma is characterized, among other features, by microenvironmental factors and by an altered apoptotic machinery. Melanoma cell response to a hypoxic environment is transcriptionally regulated by the Hypoxia-Inducible Factor (HIF)-1α. p75 neurotrophin receptor (p75(NTR) ), also called CD271, mediates apoptosis in several cell systems. The purpose of this study was to analyze the expression of HIF-1α and CD271 in melanomas at different phases of progression, as evaluated by histology and reflectance confocal microscopy (RCM). By RCM, 41.67% tumors were characterized by the presence of a population of dendritic and pleomorphic cells (D+P), corresponding to in situ melanoma; 25% exhibited a predominantly round-cell (RN) proliferation with histologic features of superficial melanoma, and 33.33% showed the presence of cells aggregated in nests (DN), typical of invasive melanoma. HIF-1α was scarcely detected in D+P and in RN melanomas, while it was highly expressed in DN tumors. By contrast, CD271 positive cells were mostly detected in D+P population, and barely observed in the other subtypes. This work demonstrates that CD271 expression inversely correlates with hypoxia in melanoma, and that the two markers may be used in the future as diagnostic/prognostic tools for this neoplasm. PMID:25739328

  17. MURINE PULMONARY RESPONSE TO CHRONIC HYPOXIA IS STRAIN SPECIFIC

    PubMed Central

    Tada, Yuji; Laudi, Sven; Harral, Julie; Carr, Michelle; Ivester, Charles; Tanabe, Nobuhiro; Takiguchi, Yuichi; Tatsumi, Koichiro; Kuriyama, Takayuki; Nichols, William C.; West, James

    2013-01-01

    Information concerning the effects of genetic variation between different background strains on hemodynamic, morphometric, and gene expression response to hypoxia would be useful. Three strains of mice were kept in hypoxia and phenotyped followed by gene profiling analysis. Among the variables examined, hematocrit, right heart muscularization, and right ventricular systolic pressure showed a strain-specific effect. Increased gene expression of inflammatory, muscle, and angiogenesis genes were seen in all strains, though the specific genes changed varied among groups. These results suggest that different strains use different gene expression mechanisms to adapt to the challenge of chronic hypoxia, resulting in modified phenotypic changes. PMID:18600498

  18. Developing vascular and hypoxia based theranostics in solid tumors

    NASA Astrophysics Data System (ADS)

    Koonce, Nathan A.

    Tissue hypoxia was recognized for its biological attenuating effects on ionizing radiation over a century ago and is a characteristic feature of many solid tumors. Clinical and experimental evidence indicates tumor hypoxia plays diverse and key roles in tumor progression, angiogenesis, and resistance to chemotherapy/radiotherapy. Hypoxia has known effects on progression and resistance to several standard treatment approaches and the significant history of study might suggest diagnostic imaging and therapeutic interventions would be routine in oncological practice. Curiously, this is not the case and the research results involved in this report will attempt to better understand and contribute to why this gap in knowledge exists and a rationale for harnessing the potential of detecting and targeting hypoxia. Despite the addition of oxygen and reversal of hypoxia being known as the best radiosensitizer, hypoxia remains unexploited in clinical cancer therapy. The studies reported herein detail development of a novel imaging technique to detect a subtype of tumor hypoxia, vascular hypoxia or hypoxemia, with a 17-fold increase (p<0.05) in uptake of pimonidazole targeted microbubbles observed compared to controls. This technique creates the potential to study the role of hypoxemia in progression and therapeutic response. Additionally, description of a nanoparticle-based therapy that targets tumor areas associated with tumor hypoxia and the tumor microenvironment in general is reported. TNF-loaded nanoparticles combined with radiotherapy resulted in a 5.25-fold growth delay that was found to be synergistic (p<0.05) and suggests clinical evaluation is warranted. An additional study to evaluate an approach to use thermal ablation of intratumoral hypoxia by an image-guided technique developed in our group is described along with a sequence dependence of radiation preceding ablation. A final study on the use of galectin-1 antagonist to significantly decrease (p<0.05) hypoxia

  19. Investigation of the combined effects of bedrest and mild hypoxia

    NASA Technical Reports Server (NTRS)

    Waligora, J. M.; Horrigan, D. J., Jr.; Bungo, M. W.; Conkin, J.

    1982-01-01

    Subjects were exposed to an 8-h mild hypoxia exposure (8000 ft. equivalent, 2438 m) with and without a 28-h period of 6 deg headdown bedrest. Anticipated responses to the bedrest and the hypoxia were observed. There was no indication that bedrest affected the arterial oxygenation or the oxygen gradient across the lungs of the subjects undergoing mild hypoxia. It is concluded that there is no evidence that would preclude an alveolar O2 pressure as low as 69 torr during contingency spacecraft operation.

  20. Modulation of human sinus node function by systemic hypoxia

    NASA Technical Reports Server (NTRS)

    Eckberg, D. L.; Bastow, H., III; Scruby, A. E.

    1982-01-01

    The present study was conducted to determine whether bradycardia develops during systemic hypoxia in supine conscious human volunteers when respiratory frequency and tidal volume are maintained at constant levels. The obtained results suggest that mild hypoxia provokes cardioacceleration in humans, independent of changes of ventilation or baroreflex responsiveness. The earliest cardioacceleration is more prominent in the inspiratory than in the expiratory phase of respiration, and occurs with very small reductions of arterial oxygen saturation. Moderate systemic hypoxia dampens fluctuations of heart rate during the respiratory cycle.

  1. Hypoxia inducible factor-1 alpha and multiple myeloma

    PubMed Central

    Tiwary, Bhupendra Nath

    2016-01-01

    Rapid tumor growth creates a state of hypoxia in the tumor microenvironment and results in release of hypoxia inducible factor-1 alpha (HiF-1α) in the local milieu. Hypoxia inducible factor activity is deregulated in many human cancers, especially those that are highly hypoxic. In multiple myeloma (MM) in initial stages of disease establishment, the hypoxic bone marrow microenvironment supports the initial survival and growth of the myeloma cells. Hypoxic tumour cells are usually resistant to radiotherapy and most conventional chemotherapeutic agents, rendering them highly aggressive and metastatic. Therefore, HIF is an attractive, although challenging, therapeutic target in MM directly or indirectly in recent years. PMID:26900575

  2. Intrinsic structure in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Albers, N.

    2015-10-01

    Saturn's rings are the most prominent in our Solar system and one example of granular matter in space. Dominated by tides and inelastic collisions the system is highly flattened being almost 300000km wide while only tens of meters thick. Individual particles are composed of primarily water ice and range from microns to few tens of meters in size. Apparent patterns comprise ringlets, gaps, kinematic wakes, propellers, bending waves, and the winding spiral arms of density waves. These large-scale structures are perturbations foremost created by external as well as embedded moons. Observations made by the Cassini spacecraft currently in orbit around Saturn show these structures in unprecedented detail. But high-resolution measurements reveal the presence of small-scale structures throughout the system. These include self-gravity wakes (50-100m), overstable waves (100-300m), subkm structure at the A and B ring edges, "straw" and "ropy" structures (1-3km), and the C ring "ghosts". Most of these had not been anticipated and are found in perturbed regions, driven by resonances with external moons, where the system undergoes periodic phases of compression and relaxation that correlate with the presence of structure. High velocity dispersion and the presence of large clumps imply structure formation on time scales as short as one orbit (about 10 hours). The presence of these intrinsic structures is seemingly the response to varying local conditions such as internal density, optical depth, underlying particle size distribution, granular temperature, and distance from the central planet. Their abundance provides evidence for an active and dynamic ring system where aggregation and fragmentation are ongoing on orbital timescales. Thus a kinetic description of the rings may be more appropriate than the fluid one. I will present Cassini Ultraviolet Spectrometer (UVIS) High Speed Photometer (HSP) occultations, Voyager 1 and 2 Imaging Science Subsystem (ISS), and high

  3. [Interaction of hypoxia and haemostasis--hypoxia as a prothrombotic factor at high altitude?].

    PubMed

    Schobersberger, Wolfgang; Hoffmann, Georg; Gunga, Hanns-Christian

    2005-04-01

    For an extended period of time various research projects have been conducted on the relationship of hypoxia and haemostasis. The enclosed article contains the conclusion to which extent lack of oxygen can activate the coagulation system and induce a prothrombotic state. The majority of studies proved a shortening of coagulation times during acute exposure to hypoxia, whereas activated parameters of coagulation and fibrinolysis like prothrombin fragment F1+2 as well as thrombin-antithrombin III complexes and D-dimer remained mostly unmodified. It is suggested that a prolonged sojourn at high altitudes could lead to activation of the coagulation system through an increase of haematocrit and blood viscosity. Recently it was proven that people living at high altitudes show an enhanced risk of stroke incidents. The significance of the change in haemostasis on that outcome has not yet been part of the research. However, it has been proven that the activity of the coagulation system does not play a pathophysiological part in the development of acute mountain sickness and high altitude pulmonary edema. Recent studies also demonstrated that moderate hypoxia during long haul flights may not be the main trigger in inducing deep vein thrombosis in passengers. PMID:15966261

  4. Chronic intermittent hypoxia alters ventilatory and metabolic responses to acute hypoxia in rats.

    PubMed

    Morgan, Barbara J; Adrian, Russell; Wang, Zun-Yi; Bates, Melissa L; Dopp, John M

    2016-05-15

    We determined the effects of chronic exposure to intermittent hypoxia (CIH) on chemoreflex control of ventilation in conscious animals. Adult male Sprague-Dawley rats were exposed to CIH [nadir oxygen saturation (SpO2), 75%; 15 events/h; 10 h/day] or normoxia (NORM) for 21 days. We assessed the following responses to acute, graded hypoxia before and after exposures: ventilation (V̇e, via barometric plethysmography), V̇o2 and V̇co2 (analysis of expired air), heart rate (HR), and SpO2 (pulse oximetry via neck collar). We quantified hypoxia-induced chemoreceptor sensitivity by calculating the stimulus-response relationship between SpO2 and the ventilatory equivalent for V̇co2 (linear regression). An additional aim was to determine whether CIH causes proliferation of carotid body glomus cells (using bromodeoxyuridine). CIH exposure increased the slope of the V̇e/V̇co2/SpO2 relationship and caused hyperventilation in normoxia. Bromodeoxyuridine staining was comparable in CIH and NORM. Thus our CIH paradigm augmented hypoxic chemosensitivity without causing glomus cell proliferation. PMID:26917692

  5. Adipose differentiation-related protein is not involved in hypoxia inducible factor-1-induced lipid accumulation under hypoxia

    PubMed Central

    SHEN, GUOMIN; NING, NING; ZHAO, XINGSHENG; LIU, XI; WANG, GUANGYU; WANG, TIANZHEN; ZHAO, RAN; YANG, CHAO; WANG, DONGMEI; GONG, PINGYUAN; SHEN, YAN; SUN, YONGJIAN; ZHAO, XIAO; JIN, YINJI; YANG, WEIWEI; HE, YAN; ZHANG, LEI; JIN, XIAOMING; LI, XIAOBO

    2015-01-01

    Increasing evidence has showed that hypoxia inducible factor-1 (HIF1) has an important role in hypoxia-induced lipid accumulation, a common feature of solid tumors; however, its role remains to be fully elucidated. Adipose differentiation-related protein (ADRP), a structural protein of lipid droplets, is found to be upregulated under hypoxic conditions. In the present study, an MCF7 breast cancer cell line was used to study the role of ADRP in hypoxia-induced lipid accumulation. It was demonstrated that hypoxia induced the gene expression of ADRP in a HIF1-dependent manner. Increases in the mRNA and protein levels of ADRP was accompanied by increased HIF1A activity. In addition, a significant decrease in the mRNA and protein levels of ADRP were detected in presence of siRNA targeting HIF1A. Using a dual-luciferase reporting experiment and chromatin immunoprecipitation assay, the present study demonstrated that ADRP is a direct target gene of HIF1, and identified a functional hypoxia response element localized 33 bp upstream of the transcriptional start site of the ADRP gene. Furthermore, the present study demonstrated the role of ADRP in low density liporotein (LDL) and very-LDL uptake-induced lipid accumulation under hypoxia. The knockdown of ADRP did not reduce HIF1-induced lipid accumulation under hypoxia. Together, these results showed that ADRP may be not involved in HIF1-induced lipid accumulation. PMID:26498183

  6. Mitochondrial physiology and reactive oxygen species production are altered by hypoxia acclimation in killifish (Fundulus heteroclitus).

    PubMed

    Du, Sherry N N; Mahalingam, Sajeni; Borowiec, Brittney G; Scott, Graham R

    2016-04-15

    Many fish encounter hypoxia in their native environment, but the role of mitochondrial physiology in hypoxia acclimation and hypoxia tolerance is poorly understood. We investigated the effects of hypoxia acclimation on mitochondrial respiration, O2kinetics, emission of reactive oxygen species (ROS), and antioxidant capacity in the estuarine killifish ( ITALIC! Fundulus heteroclitus). Killifish were acclimated to normoxia, constant hypoxia (5 kPa O2) or intermittent diel cycles of nocturnal hypoxia (12 h:12 h normoxia:hypoxia) for 28-33 days and mitochondria were isolated from liver. Neither pattern of hypoxia acclimation affected the respiratory capacities for oxidative phosphorylation or electron transport, leak respiration, coupling control or phosphorylation efficiency. Hypoxia acclimation also had no effect on mitochondrial O2kinetics, but ITALIC! P50(the O2tension at which hypoxia inhibits respiration by 50%) was lower in the leak state than during maximal respiration, and killifish mitochondria endured anoxia-reoxygenation without any impact on mitochondrial respiration. However, both patterns of hypoxia acclimation reduced the rate of ROS emission from mitochondria when compared at a common O2tension. Hypoxia acclimation also increased the levels of protein carbonyls and the activities of superoxide dismutase and catalase in liver tissue (the latter only occurred in constant hypoxia). Our results suggest that hypoxia acclimation is associated with changes in mitochondrial physiology that decrease ROS production and may help improve hypoxia tolerance. PMID:26896545

  7. Intrinsic operators for the electromagnetic nuclear current

    SciTech Connect

    J. Adam, Jr.; H. Arenhovel

    1996-09-01

    The intrinsic electromagnetic nuclear meson exchange charge and current operators arising from a separation of the center-of-mass motion are derived for a one-boson-exchange model for the nuclear interaction with scalar, pseudoscalar and vector meson exchange including leading order relativistic terms. Explicit expressions for the meson exchange operators corresponding to the different meson types are given in detail for a two-nucleon system. These intrinsic operators are to be evaluated between intrinsic wave functions in their center-of-mass frame.

  8. Heat acclimation and cross tolerance to hypoxia

    PubMed Central

    Ely, Brett R; Lovering, Andrew T; Horowitz, Michal; Minson, Christopher T

    2014-01-01

    Recent research has suggested a potential for some of the physiological and cellular responses to heat acclimation to carry over to improved tolerance of the novel stresses of another environment. This cross-tolerance is evident in heat-acclimated animals that exhibit enhanced tolerance to either hypoxic or ischemic stress, and is primarily attributed to shared cellular stress response pathways. These pathways include Hypoxia-Inducible Factor-1 (HIF-1) and Heat Shock Proteins (HSP). Whether these shared cellular stress response pathways translate to systemic cross-tolerance (improved exercise tolerance, reduced risk of environment-associated illness) has not been clearly shown, particularly in humans. This review highlights the HIF-1 and HSP pathways and their relationship with systemic acclimation responses, and further examines the potential cellular and systemic adaptations that may result in cross-tolerance between hot and hypoxic environments.

  9. Hypoxia-Specific Cytotoxins in Cancer Therapy.

    PubMed

    Brown; Siim

    1996-01-01

    Hypoxic-specific cytotoxins are a new, and as yet clinically untested, mode of treatment of solid tumors. If they can be given at high enough concentrations and sufficiently often, they should prove extremely effective both in combination with standard radiotherapy and also with certain chemotherapeutic drugs. It is likely that their optimum use will turn hypoxic cells in solid tumors from a therapeutic disadvantage to an advantage. In this report, we review the rationale for the use of hypoxia- cytotoxins, including both the theoretical basis for combining them with fractionated radiation and the preclinical results that have been obtained to date combing these agents with fractionated radiation. We also discuss the three major classes of bioreductive drugs, including the quinones (mitomycin C, porfiromycin, and E09), notroaromatic compounds (including RB6145 and various deoxyribonucleic acid [DNA] targeted aromatics), and finally the n-oxides of which tirapazamine is the lead compound. We also briefly discuss new approaches to bioreductive drug development. The best ways to use these agents are also covered. These include using them in combination with radiation, in combination with chemotherapy, and in combination with agents that increase tumor hypoxia. Finally, the importance of the selection of patients for clinical trials is illustrated by showing how dramatically the number of patients for clinical trials is illustrated by showing how dramatically the number of patients in a clinical trial has to increase to obtain statistical significance for a procedure targeted towards hypoxic cells if some of the patients in the trials have well-oxygenated tumors. PMID:10717159

  10. The Effect of Prenatal Hypoxia on Brain Development: Short- and Long-Term Consequences Demonstrated in Rodent Models

    ERIC Educational Resources Information Center

    Golan, Hava; Huleihel, Mahmoud

    2006-01-01

    Hypoxia (H) and hypoxia-ischemia (HI) are major causes of foetal brain damage with long-lasting behavioral implications. The effect of hypoxia has been widely studied in human and a variety of animal models. In the present review, we summarize the latest studies testing the behavioral outcomes following prenatal hypoxia/hypoxia-ischemia in rodent…

  11. Micro Regional Heterogeneity of 64Cu-ATSM and 18F-FDG Uptake in Canine Soft Tissue Sarcomas: Relation to Cell Proliferation, Hypoxia and Glycolysis

    PubMed Central

    Zornhagen, Kamilla Westarp; Hansen, Anders E.; Oxboel, Jytte; Clemmensen, Andreas E.; El Ali, Henrik H.; Kristensen, Annemarie T.; Kjær, Andreas

    2015-01-01

    Objectives Tumour microenvironment heterogeneity is believed to play a key role in cancer progression and therapy resistance. However, little is known about micro regional distribution of hypoxia, glycolysis and proliferation in spontaneous solid tumours. The overall aim was simultaneous investigation of micro regional heterogeneity of 64Cu-ATSM (hypoxia) and 18F-FDG (glycolysis) uptake and correlation to endogenous markers of hypoxia, glycolysis, proliferation and angiogenesis to better therapeutically target aggressive tumour regions and prognosticate outcome. Methods Exploiting the different half-lives of 64Cu-ATSM (13h) and 18F-FDG (2h) enabled simultaneous investigation of micro regional distribution of hypoxia and glycolysis in 145 tumour pieces from four spontaneous canine soft tissue sarcomas. Pairwise measurements of radioactivity and gene expression of endogenous markers of hypoxia (HIF-1α, CAIX), glycolysis (HK2, GLUT1 and GLUT3), proliferation (Ki-67) and angiogenesis (VEGFA and TF) were performed. Dual tracer autoradiography was compared with Ki-67 immunohistochemistry. Results Micro regional heterogeneity in hypoxia and glycolysis within and between tumour sections of each tumour piece was observed. The spatial distribution of 64Cu-ATSM and 18F-FDG was rather similar within each tumour section as reflected in moderate positive significant correlations between the two tracers (ρ = 0.3920–0.7807; p = 0.0180 –<0.0001) based on pixel-to-pixel comparisons of autoradiographies and gamma counting of tumour pieces. 64Cu-ATSM and 18F-FDG correlated positively with gene expression of GLUT1 and GLUT3, but negatively with HIF-1α and CAIX. Significant positive correlations were seen between Ki-67 gene expression and 64Cu-ATSM (ρ = 0.5578, p = 0.0004) and 18F-FDG (ρ = 0.4629–0.7001, p = 0.0001–0.0151). Ki-67 gene expression more consistently correlated with 18F-FDG than with 64Cu-ATSM. Conclusions Micro regional heterogeneity of hypoxia and glycolysis

  12. [MUSCULOSKELETAL MARKERS, ARTHROPATY, TRAUMAS].

    PubMed

    Caldarini, Carla; Zavaroni, Federica; Benassi, Valentina

    2015-01-01

    The bone tissue remodeling due to strong physical/working activity is defined as ergonomic markers or MSM (Muscoloskeletal Stress Markers) (Capasso et al. 1999) and MOS (Markers of Occupational Stress). Among them we can find: enthesopaties, arthropaties, non metrical stress and traumas markers. In the present study, the analysis of these traits has been used to clarify habitual activity patterns of four imperial populations from Suburbium: Castel Malnome, Casal Bertone area Q, Via Padre Semeria e Quarto Cappello del Prete. The very high prevalence of activity-induced stress lesions occurred among the individuals of Castel Malnome and Casal Bertone area Q suggests that these groups were involved in strenuous occupations such as, respectively: the processing and storage of salt and the dyeing of textiles and hides discernible from the archaeological context. For the individuals of Via Padre Semeria and Quarto Cappello del Prete the alterations, instead, could be compatibles with agricultural work. PMID:27348990

  13. Phenotypic transition of corpus cavernosum smooth muscle cells subjected to hypoxia.

    PubMed

    Lv, Bodong; Zhao, Jianfeng; Yang, Fan; Huang, Xiaojun; Chen, Gang; Yang, Kebing; Liu, Shanshan; Fan, Chunlei; Fu, Huiying; Chen, Zhaodian

    2014-09-01

    Corpora cavernosum smooth muscle cells (CCSMCs) have been shown to play a critical role in the male erectile response and are involved in the pathogenesis of multiple causes of erectile dysfunction (ED). To investigate the underlying mechanisms, we studied the changes that CCSMCs undergo under hypoxic conditions in vitro. The identified and characterized CCSMCs were exposed to hypoxia for 48 h and its phenotypic changes were examined by light and electron microscopy, MTS assay and flow cytometry. The mRNA and protein levels of TGF-β1 and type I/III collagen, as well as CCSMC phenotype marker proteins and their transcriptional factors, were assessed by qPCR, immunofluorescence analysis and western blotting. Our results showed that CCSMCs became hypertrophic with loss of myofilament bundles and formation of an extensive rough endoplasmic reticulum (RER) under hypoxic conditions, with inhibited cell proliferation and enhanced cell apoptosis. This was accompanied by the increased synthesis of TGF-β1 and types I and III collagen. Moreover, smooth muscle cell phenotypic markers were also affected by hypoxic conditions, as indicated by the decrease in α-SMA, desmin and CNN1 expression and the increase in vimentin expression. These changes corresponded to changes in associated transcriptional factors, such as the increase in Elk-1 and KLF-4 expression and decrease in Myocd expression. In addition, a HIF-1α knockdown effectively reversed the hypoxia-induced CCSMC phenotype, whereas its overexpression induced the dedifferentiation phenotype. These results indicate that CCSMCs undergo a phenotypic transition under hypoxic conditions. PMID:24913687

  14. DUBs, New Members in the Hypoxia Signaling clUb

    PubMed Central

    Schober, Amelie S.; Berra, Edurne

    2016-01-01

    Cellular protein homeostasis is tightly regulated by ubiquitination. Responsible for target protein ubiquitination is a class of enzymes, the so-called ubiquitin E3 ligases. They are opposed to a second class of enzymes, called deubiquitinating enzymes (DUBs), which can remove polyubiquitin chains from their specific target proteins. The coaction of the two sets of enzymes allows the cell to adapt its overall protein content and the abundance of particular proteins to a variety of cellular and environmental stresses, including hypoxia. In recent years, DUBs have been highlighted to play major roles in many diseases, including cancer, both as tumor suppressors and oncogenes. Therefore, DUBs are emerging as promising targets for cancer-cell specific treatment. Here, we will review the current understanding of DUBs implicated in the control of hypoxia-inducible factor, the regulation of DUBs by hypoxia, and the use of DUB-specific drugs to target tumor hypoxia-signaling. PMID:27014628

  15. Vascular Endothelial growth factor signaling in hypoxia and Inflammation

    PubMed Central

    Ramakrishnan, S.; Anand, Vidhu; Roy, Sabita

    2014-01-01

    Infection, cancer and cardiovascular diseases are the major causes for morbidity and mortality in the United States according to the Center for Disease Control. The underlying etiology that contributes to the severity of these diseases is either hypoxia induced inflammation or inflammation resulting in hypoxia. Therefore, molecular mechanisms that regulate hypoxia-induced adaptive responses in cells are important areas of investigation. Oxygen availability is sensed by molecular switches which regulate synthesis and secretion of growth factors and inflammatory mediators. As a consequence, tissue microenvironment is altered by reprogramming metabolic pathways, angiogenesis, vascular permeability, pH homeostasis to facilitate tissue remodeling. Hypoxia inducible factor (HIF) is the central mediator of hypoxic response. HIF regulates several hundred genes and vascular endothelial growth factor (VEGF) is one of the primary target genes. Understanding the regulation of HIF and its influence on inflammatory response offers unique opportunities for drug development to modulate inflammation and ischemia in pathological conditions. PMID:24610033

  16. Hypoxia-inducible factor 1 in autoimmune diseases.

    PubMed

    Deng, Wei; Feng, Xuebing; Li, Xia; Wang, Dandan; Sun, Lingyun

    2016-05-01

    Autoimmune disorders are a complicated and varied group of diseases arising from inappropriate immune responses. Recent studies have demonstrated that ongoing inflammatory and immune responses are associated with increased oxygen consumption, a process resulting in localized tissue hypoxia within inflammatory lesions ("inflammatory hypoxia"), in which hypoxia-inducible factor 1 (HIF-1), an oxygen-sensitive transcription factor that allows adaptation to hypoxia environments, has been shown to play an important function. HIF-1 is a regulator of angiogenesis and immune system. Besides, HIF-1-mediated metabolic shift and fibrosis may also play crucial roles in some autoimmune disorders. Firstly, we briefly summarize the role of HIF-1 in angiogenesis, immune responses and fibrosis. Secondly, we will show the major recent findings demonstrating a role for HIF-1 signaling in autoimmune disorders, including rheumatoid arthritis, inflammatory bowel disease, psoriasis, systemic sclerosis and multiple sclerosis. The growing evidences may prompt HIF-1 to be a new target for treatment of autoimmune diseases. PMID:27071377

  17. Rearing of silkworm under hypobaric and hypoxia conditions

    NASA Astrophysics Data System (ADS)

    Hashimoto, Hirofumi; Nakayama, Shin; Yamashita, Masamichi; Space Agriculture Task Force, J.

    In order to investigate of a possibility of utilizing silkworm for the space agriculture, rearing of silkworms was examined under hypobaric and hypoxia conditions. In terms of structural mechanics, the lower inner pressure of Martian greenhouse has advantage to reduce requirements on physical properties of mechanical member of the pressurized structure. The main objective of this study is to know the influence of lower total pressure and hypoxia condition on silkworm. Silkworms are reared under following four hypobaric and hypoxia conditions, 10kPa pure oxygen, 20kPa pure oxygen, 10kPa oxygen and 10kPa nitrogen, and 10kPa oxygen and 90kPa nitrogen. After rearing them to pupa stage, growth of silkworms was found poor under all hypobaric hypoxia conditions compared to those grown under the normal atmospheric condition; the control group. The growth under total pressure of 20kPa is slightly fast.

  18. Cycling hypoxia and free radicals regulate angiogenesis and radiotherapy response

    PubMed Central

    Dewhirst, Mark W.; Cao, Yiting; Moeller, Benjamin

    2014-01-01

    Hypoxia and free radicals, such as reactive oxygen and nitrogen species, can alter the function and/or activity of the transcription factor hypoxia-inducible factor 1 (HIF1). Interplay between free radicals, hypoxia and HIF1 activity is complex and can influence the earliest stages of tumour development. The hypoxic environment of tumours is heterogeneous, both spatially and temporally, and can change in response to cytotoxic therapy. Free radicals created by hypoxia, hypoxia–reoxygenation cycling and immune cell infiltration after cytotoxic therapy strongly influence HIF1 activity. HIF1 can then promote endothelial and tumour cell survival. As discussed here, a constant theme emerges: inhibition of HIF1 activity will have therapeutic benefit. PMID:18500244

  19. Role of posterior hypothalamus in hypobaric hypoxia induced pulmonary edema.

    PubMed

    Sharma, R K; Choudhary, R C; Reddy, M K; Ray, A; Ravi, K

    2015-01-01

    To investigate the role of posterior hypothalamus and central neurotransmitters in the pulmonary edema due to hypobaric hypoxia, rats were placed in a high altitude simulation chamber (barometric pressure-294.4 mmHg) for 24 h. Exposure to hypobaric hypoxia resulted in increases in mean arterial blood pressure, renal sympathetic nerve activity, right ventricular systolic pressure, lung wet to dry weight ratio and Evans blue dye leakage. There was a significant attenuation in these responses to hypobaric hypoxia (a) after lesioning posterior hypothalamus and (b) after chronic infusion of GABAA receptor agonist muscimol into posterior hypothalamus. No such attenuation was evident with the chronic infusion of the nitric oxide donor SNAP into the posterior hypothalamus. It is concluded that in hypobaric hypoxia, there is over-activity of posterior hypothalamic neurons probably due to a local decrease in GABA-ergic inhibition which increases the sympathetic drive causing pulmonary hypertension and edema. PMID:25448396

  20. [Biological markers of alcoholism].

    PubMed

    Marcos Martín, M; Pastor Encinas, I; Laso Guzmán, F J

    2005-09-01

    Diagnosis of alcoholism is very important, given its high prevalence and possibility of influencing the disease course. For this reason, the so-called biological markers of alcoholism are useful. These are analytic parameters that alter in the presence of excessive alcohol consumption. The two most relevant markers are the gamma-glutamyltranspeptidase and carbohydrate deficient transferrin. With this clinical comment, we aim to contribute to the knowledge of these tests and promote its use in the clinical practice. PMID:16194480

  1. Stress-induced salivary cortisol secretion during hypobaric hypoxia challenge and in vivo urinary thromboxane production in healthy male subjects.

    PubMed

    Simeoni, Simona; Biselli, Roberto; D'Amelio, Raffaele; Rocca, Bianca; Lattanzio, Stefano; Mucci, Luciana; Davì, Giovanni; Patacchioli, Francesca Romana

    2011-05-01

    Few studies have assessed the effects of stress on in vivo platelet activation. In the present study, hypobaric hypoxia induced by rapid decompression during high-altitude simulated flight in a hypobaric chamber was used to evaluate the effects of environmental stress on salivary cortisol and urinary thromboxane metabolite (TXM) excretion, a noninvasive marker of in vivo platelet function. Twenty-one male aviators (mean ± SD age = 36 ± 7 years) experiencing hypoxia by removing their oxygen mask for 4-5 min during a simulated flight to 25,000 ft (7,620 m; pO(2) = 59.17 mmHg) and a matched control group of thirteen flying instructors wearing oxygen masks during the challenge, were studied. Hypobaric hypoxia induced a transient significant increase (P < 0.001) in the aviators' salivary cortisol concentration; the overall pattern of diurnal cortisol fluctuation was maintained in both groups. Urinary TXM showed a significant ∼30% reduction (P < 0.01) after the chamber session in aviators exposed to hypobaric hypoxia, but not in controls. A significant inverse correlation was found between salivary cortisol and urinary TXM in aviators (r = - 0.64, P = 0.0015). Salivary cortisol was a significant predictor (P < 0.001) for urinary TXM concentrations in aviators. In conclusion, here we observed that an acute stress-induced salivary cortisol increase was associated with reduced urinary thromboxane biosynthesis, providing the first indirect evidence for an inhibitory effect of acute stress on in vivo platelet function. PMID:21434833

  2. Carbonic anhydrase IX, a hypoxia-induced catalytic component of the pH regulating machinery in tumors.

    PubMed

    Sedlakova, Olga; Svastova, Eliska; Takacova, Martina; Kopacek, Juraj; Pastorek, Jaromir; Pastorekova, Silvia

    2014-01-01

    Acidic tissue microenvironment contributes to tumor progression via multiple effects including the activation of angiogenic factors and proteases, reduced cell-cell adhesion, increased migration and invasion, etc. In addition, intratumoral acidosis can influence the uptake of anticancer drugs and modulate the response of tumors to conventional therapy. Acidification of the tumor microenvironment often develops due to hypoxia-triggered oncogenic metabolism, which leads to the extensive production of lactate, protons, and carbon dioxide. In order to avoid intracellular accumulation of the acidic metabolic products, which is incompatible with the survival and proliferation, tumor cells activate molecular machinery that regulates pH by driving transmembrane inside-out and outside-in ion fluxes. Carbonic anhydrase IX (CA IX) is a hypoxia-induced catalytic component of the bicarbonate import arm of this machinery. Through its catalytic activity, CA IX directly participates in many acidosis-induced features of tumor phenotype as demonstrated by manipulating its expression and/or by in vitro mutagenesis. CA IX can function as a survival factor protecting tumor cells from hypoxia and acidosis, as a pro-migratory factor facilitating cell movement and invasion, as a signaling molecule transducing extracellular signals to intracellular pathways (including major signaling and metabolic cascades) and converting intracellular signals to extracellular effects on adhesion, proteolysis, and other processes. These functional implications of CA IX in cancer are supported by numerous clinical studies demonstrating the association of CA IX with various clinical correlates and markers of aggressive tumor behavior. Although our understanding of the many faces of CA IX is still incomplete, existing knowledge supports the view that CA IX is a biologically and clinically relevant molecule, exploitable in anticancer strategies aimed at targeting adaptive responses to hypoxia and/or acidosis

  3. Carbonic anhydrase IX, a hypoxia-induced catalytic component of the pH regulating machinery in tumors

    PubMed Central

    Sedlakova, Olga; Svastova, Eliska; Takacova, Martina; Kopacek, Juraj; Pastorek, Jaromir; Pastorekova, Silvia

    2013-01-01

    Acidic tissue microenvironment contributes to tumor progression via multiple effects including the activation of angiogenic factors and proteases, reduced cell-cell adhesion, increased migration and invasion, etc. In addition, intratumoral acidosis can influence the uptake of anticancer drugs and modulate the response of tumors to conventional therapy. Acidification of the tumor microenvironment often develops due to hypoxia-triggered oncogenic metabolism, which leads to the extensive production of lactate, protons, and carbon dioxide. In order to avoid intracellular accumulation of the acidic metabolic products, which is incompatible with the survival and proliferation, tumor cells activate molecular machinery that regulates pH by driving transmembrane inside-out and outside-in ion fluxes. Carbonic anhydrase IX (CA IX) is a hypoxia-induced catalytic component of the bicarbonate import arm of this machinery. Through its catalytic activity, CA IX directly participates in many acidosis-induced features of tumor phenotype as demonstrated by manipulating its expression and/or by in vitro mutagenesis. CA IX can function as a survival factor protecting tumor cells from hypoxia and acidosis, as a pro-migratory factor facilitating cell movement and invasion, as a signaling molecule transducing extracellular signals to intracellular pathways (including major signaling and metabolic cascades) and converting intracellular signals to extracellular effects on adhesion, proteolysis, and other processes. These functional implications of CA IX in cancer are supported by numerous clinical studies demonstrating the association of CA IX with various clinical correlates and markers of aggressive tumor behavior. Although our understanding of the many faces of CA IX is still incomplete, existing knowledge supports the view that CA IX is a biologically and clinically relevant molecule, exploitable in anticancer strategies aimed at targeting adaptive responses to hypoxia and/or acidosis

  4. Distribution of hypoxia and pycnocline off the Changjiang Estuary, China

    NASA Astrophysics Data System (ADS)

    Zhu, Jianrong; Zhu, Zhuoyi; Lin, Jun; Wu, Hui; Zhang, Jing

    2016-02-01

    The distributions of hypoxia and the pycnocline off the Changjiang Estuary were investigated by making several field observations from June 2 to 11, from July 18 to 23, from August 20 to 30, from October 3 to 13, 2006, and from August 27 to September 3, 2009. The observations from July 18 to 23, 2006, mainly focused on analyzing the relationship between hypoxia and the extension of the river plume and vertical stratification. In July, the Changjiang diluted water (CDW) was influenced by the easterly typhoon winds, causing it to extend northward rather than northeastward. By using the maximum vertical density gradient as a stratification intensity index, we found that the area of low (< 3 mg/L) dissolved oxygen (DO) was similar to the area of the pycnocline (> 2.0 kg/m4), which indicated that the summer pycnocline can effectively block vertical DO exchange and maintain hypoxia near the bottom. The observed hypoxic area was 500 km2, which was much smaller than the hypoxic areas observed in previous studies, and occurred because of the enhanced mixing that resulted from Typhoon Bill. During the observation period of August 20-30, 2006, the maximum density gradient was weaker due to distinct low river discharge. No hypoxia was observed in the eastern and southeastern sea off the Changjiang Estuary where hypoxia often occurs. However, hypoxia occurred over a large area of 15,400 km2 in the northern observation domain where hypoxia rarely occurs. During June 2-11 and October 3-13, 2006, the maximum density gradient was weaker, and the area with low DO was smaller than in July 2006. This finding resulted from relatively low river discharge and weaker solar heating. Consequently, no hypoxia occurred in the bottom layer. The area of low DO was similar to that of the maximum vertical density gradient. From August 27 to September 3, 2009, high river discharge and strong solar heating produced a larger and more intense pycnocline. The hypoxic area reached 3735 km2 and was very

  5. Concentrated Hypoxia-Preconditioned Adipose Mesenchymal Stem Cell-Conditioned Medium Improves Wounds Healing in Full-Thickness Skin Defect Model.

    PubMed

    Sun, Biao; Guo, Shilei; Xu, Fei; Wang, Bin; Liu, Xiujuan; Zhang, Yuanyuan; Xu, Yan

    2014-01-01

    In recent years, the bioactive factors were utilized in exercise and athletic skin injuries. In this research, the concentrated conditioned medium of hypoxia-preconditioned adipose mesenchymal stem cells, which is rich in bioactive factor, is applied in full-thickness skin defect model to evaluate the therapeutic efficacy. Adipose mesenchymal stem cells were harvested from the abdominal subcutaneous adipose tissues. The surface markers and the potential of differentiation were analyzed. The conditioned medium of hypoxia-preconditioned stem cells was collected and freeze-dried and then applied on the rat full-thickness skin defect model, and the healing time of each group was recorded. Haematoxylin and eosin staining of skin was assessed by microscope. The characteristics of adipose mesenchymal stem cells were similar to those of other mesenchymal stem cells. The concentration of protein in freeze-dried conditioned medium in 1 mL water was about 15 times higher than in the normal condition medium. In vivo, the concentrated hypoxia-preconditioned conditioned medium can reduce the wound size and accelerate the skin wound healing. The concentrated hypoxia-preconditioned adipose mesenchymal stem cell-conditioned medium has great effect on rat model of wound healing, and it would be an ideal agent for wound care in clinical application. PMID:27433483

  6. Carbonic anhydrase IX induction defines a heterogeneous cancer cell response to hypoxia and mediates stem cell-like properties and sensitivity to HDAC inhibition.

    PubMed

    Ledaki, Ioanna; McIntyre, Alan; Wigfield, Simon; Buffa, Francesca; McGowan, Simon; Baban, Dilair; Li, Ji-Liang; Harris, Adrian L

    2015-08-14

    Carbonic anhydrase IX (CAIX) is strongly induced by hypoxia and its overexpression is associated with poor therapeutic outcome in cancer. Here, we report that hypoxia promotes tumour heterogeneity through the epigenetic regulation of CAIX. Based on hypoxic CAIX expression we identify and characterize two distinct populations of tumour cells, one that has inducible expression of CAIX and one that does not. The CAIX+ve population is enriched with cells expressing cancer stem cell markers and which have high self-renewal capacity. We show that differential CAIX expression is due to differences in chromatin structure. To further investigate the relationship between chromatin organization and hypoxic induction of CAIX expression we investigated the effect of JQ1 an inhibitor of BET bromodomain proteins and A366 a selective inhibitor of the H3K9 methyltransferase G9a/GLP. We identified that these drugs were able to modulate hypoxic CAIX expression induction. This further highlights the role of epigenetic modification in adaption to hypoxia and also in regulation of heterogeneity of cells within tumours. Interestingly, we identified that the two subpopulations show a differential sensitivity to HDAC inhibitors, NaBu or SAHA, with the CAIX positive showing greater sensitivity to treatment. We propose that drugs modulating chromatin regulation of expression may be used to reduce heterogeneity induced by hypoxia and could in combination have significant clinical consequences. PMID:26305601

  7. Carbonic anhydrase IX induction defines a heterogeneous cancer cell response to hypoxia and mediates stem cell-like properties and sensitivity to HDAC inhibition

    PubMed Central

    Wigfield, Simon; Buffa, Francesca; McGowan, Simon; Baban, Dilair; Li, Ji-liang; Harris, Adrian L.

    2015-01-01

    Carbonic anhydrase IX (CAIX) is strongly induced by hypoxia and its overexpression is associated with poor therapeutic outcome in cancer. Here, we report that hypoxia promotes tumour heterogeneity through the epigenetic regulation of CAIX. Based on hypoxic CAIX expression we identify and characterize two distinct populations of tumour cells, one that has inducible expression of CAIX and one that does not. The CAIX+ve population is enriched with cells expressing cancer stem cell markers and which have high self-renewal capacity. We show that differential CAIX expression is due to differences in chromatin structure. To further investigate the relationship between chromatin organization and hypoxic induction of CAIX expression we investigated the effect of JQ1 an inhibitor of BET bromodomain proteins and A366 a selective inhibitor of the H3K9 methyltransferase G9a/GLP. We identified that these drugs were able to modulate hypoxic CAIX expression induction. This further highlights the role of epigenetic modification in adaption to hypoxia and also in regulation of heterogeneity of cells within tumours. Interestingly, we identified that the two subpopulations show a differential sensitivity to HDAC inhibitors, NaBu or SAHA, with the CAIX positive showing greater sensitivity to treatment. We propose that drugs modulating chromatin regulation of expression may be used to reduce heterogeneity induced by hypoxia and could in combination have significant clinical consequences. PMID:26305601

  8. Concentrated Hypoxia-Preconditioned Adipose Mesenchymal Stem Cell-Conditioned Medium Improves Wounds Healing in Full-Thickness Skin Defect Model

    PubMed Central

    Sun, Biao; Guo, Shilei; Xu, Fei; Wang, Bin; Liu, Xiujuan; Zhang, Yuanyuan

    2014-01-01

    In recent years, the bioactive factors were utilized in exercise and athletic skin injuries. In this research, the concentrated conditioned medium of hypoxia-preconditioned adipose mesenchymal stem cells, which is rich in bioactive factor, is applied in full-thickness skin defect model to evaluate the therapeutic efficacy. Adipose mesenchymal stem cells were harvested from the abdominal subcutaneous adipose tissues. The surface markers and the potential of differentiation were analyzed. The conditioned medium of hypoxia-preconditioned stem cells was collected and freeze-dried and then applied on the rat full-thickness skin defect model, and the healing time of each group was recorded. Haematoxylin and eosin staining of skin was assessed by microscope. The characteristics of adipose mesenchymal stem cells were similar to those of other mesenchymal stem cells. The concentration of protein in freeze-dried conditioned medium in 1 mL water was about 15 times higher than in the normal condition medium. In vivo, the concentrated hypoxia-preconditioned conditioned medium can reduce the wound size and accelerate the skin wound healing. The concentrated hypoxia-preconditioned adipose mesenchymal stem cell-conditioned medium has great effect on rat model of wound healing, and it would be an ideal agent for wound care in clinical application. PMID:27433483

  9. Upregulated Copper Transporters in Hypoxia-Induced Pulmonary Hypertension

    PubMed Central

    Zimnicka, Adriana M.; Tang, Haiyang; Guo, Qiang; Kuhr, Frank K.; Oh, Myung-Jin; Wan, Jun; Chen, Jiwang; Smith, Kimberly A.; Fraidenburg, Dustin R.; Choudhury, Moumita S. R.; Levitan, Irena; Machado, Roberto F.; Kaplan, Jack H.; Yuan, Jason X.-J.

    2014-01-01

    Pulmonary vascular remodeling and increased arterial wall stiffness are two major causes for the elevated pulmonary vascular resistance and pulmonary arterial pressure in patients and animals with pulmonary hypertension. Cellular copper (Cu) plays an important role in angiogenesis and extracellular matrix remodeling; increased Cu in vascular smooth muscle cells has been demonstrated to be associated with atherosclerosis and hypertension in animal experiments. In this study, we show that the Cu-uptake transporter 1, CTR1, and the Cu-efflux pump, ATP7A, were both upregulated in the lung tissues and pulmonary arteries of mice with hypoxia-induced pulmonary hypertension. Hypoxia also significantly increased expression and activity of lysyl oxidase (LOX), a Cu-dependent enzyme that causes crosslinks of collagen and elastin in the extracellular matrix. In vitro experiments show that exposure to hypoxia or treatment with cobalt (CoCl2) also increased protein expression of CTR1, ATP7A, and LOX in pulmonary arterial smooth muscle cells (PASMC). In PASMC exposed to hypoxia or treated with CoCl2, we also confirmed that the Cu transport is increased using 64Cu uptake assays. Furthermore, hypoxia increased both cell migration and proliferation in a Cu-dependent manner. Downregulation of hypoxia-inducible factor 1α (HIF-1α) with siRNA significantly attenuated hypoxia-mediated upregulation of CTR1 mRNA. In summary, the data from this study indicate that increased Cu transportation due to upregulated CTR1 and ATP7A in pulmonary arteries and PASMC contributes to the development of hypoxia-induced pulmonary hypertension. The increased Cu uptake and elevated ATP7A also facilitate the increase in LOX activity and thus the increase in crosslink of extracellular matrix, and eventually leading to the increase in pulmonary arterial stiffness. PMID:24614111

  10. Hypoxia-Induced Alternative Splicing in Endothelial Cells

    PubMed Central

    Weigand, Julia E.; Boeckel, Jes-Niels; Gellert, Pascal; Dimmeler, Stefanie

    2012-01-01

    Background Adaptation to low oxygen by changing gene expression is vitally important for cell survival and tissue development. The sprouting of new blood vessels, initiated from endothelial cells, restores the oxygen supply of ischemic tissues. In contrast to the transcriptional response induced by hypoxia, which is mainly mediated by members of the HIF family, there are only few studies investigating alternative splicing events. Therefore, we performed an exon array for the genome-wide analysis of hypoxia-related changes of alternative splicing in endothelial cells. Methodology/Principal findings Human umbilical vein endothelial cells (HUVECs) were incubated under hypoxic conditions (1% O2) for 48 h. Genome-wide transcript and exon expression levels were assessed using the Affymetrix GeneChip Human Exon 1.0 ST Array. We found altered expression of 294 genes after hypoxia treatment. Upregulated genes are highly enriched in glucose metabolism and angiogenesis related processes, whereas downregulated genes are mainly connected to cell cycle and DNA repair. Thus, gene expression patterns recapitulate known adaptations to low oxygen supply. Alternative splicing events, until now not related to hypoxia, are shown for nine genes: six which are implicated in angiogenesis-mediated cytoskeleton remodeling (cask, itsn1, larp6, sptan1, tpm1 and robo1); one, which is involved in the synthesis of membrane-anchors (pign) and two universal regulators of gene expression (cugbp1 and max). Conclusions/Significance For the first time, this study investigates changes in splicing in the physiological response to hypoxia on a genome-wide scale. Nine alternative splicing events, until now not related to hypoxia, are reported, considerably expanding the information on splicing changes due to low oxygen supply. Therefore, this study provides further knowledge on hypoxia induced gene expression changes and presents new starting points to study the hypoxia adaptation of endothelial cells

  11. International hypoxia symposium XVIII: 26 February-02 March 2013.

    PubMed

    Pun, Matiram; Basnyat, Buddha

    2013-01-01

    The 18th International Hypoxia Symposia, Lake Louise, Alberta, Canada, February 26-March 02, 2013, covered molecular basis of hypoxic responses (e.g., hypoxia inducible factor, nitrite, nitrate, and hemoglobin) and integrative physiology (e.g., exercise physiology, cerebral blood flow responses, live-high train-low, and population genetics). Free communications and poster sessions covered scientific areas from controlled lab settings to field settings of high altitudes (Andes to Himalayas). PMID:24229461

  12. Circulatory responses to hypoxia in experimental myocardial infarction.

    NASA Technical Reports Server (NTRS)

    Schroll, M.; Robison, S. C.; Harrison, D. C.

    1971-01-01

    Three levels of decreased arterial oxygen saturation elicited a graded circulatory response in dogs, manifested by stepwise increases in cardiac output, left ventricular dp/dt, and stroke volume, and decreases in systemic vascular resistance. Responses to similar hypoxia challenges after experimental myocardial infarction were qualitatively similar but quantitatively less. Although the circulatory compensation for hypoxia was less effective after myocardial infarction, no further deterioration of the haemodynamics was noted.

  13. Increased hemoglobin O2 affinity protects during acute hypoxia.

    PubMed

    Yalcin, Ozlem; Cabrales, Pedro

    2012-08-01

    Acclimatization to hypoxia requires time to complete the adaptation mechanisms that influence oxygen (O(2)) transport and O(2) utilization. Although decreasing hemoglobin (Hb) O(2) affinity would favor the release of O(2) to the tissues, increasing Hb O(2) affinity would augment arterial O(2) saturation during hypoxia. This study was designed to test the hypothesis that pharmacologically increasing the Hb O(2) affinity will augment O(2) transport during severe hypoxia (10 and 5% inspired O(2)) compared with normal Hb O(2) affinity. RBC Hb O(2) affinity was increased by infusion of 20 mg/kg of 5-hydroxymethyl-2-furfural (5HMF). Control animals received only the vehicle. The effects of increasing Hb O(2) affinity were studied in the hamster window chamber model, in terms of systemic and microvascular hemodynamics and partial pressures of O(2) (Po(2)). Pimonidazole binding to hypoxic areas of mice heart and brain was also studied. 5HMF decreased the Po(2) at which the Hb is 50% saturated with O(2) by 12.6 mmHg. During 10 and 5% O(2) hypoxia, 5HMF increased arterial blood O(2) saturation by 35 and 48% from the vehicle group, respectively. During 5% O(2) hypoxia, blood pressure and heart rate were 58 and 30% higher for 5HMF compared with the vehicle. In addition, 5HMF preserved microvascular blood flow, whereas blood flow decreased to 40% of baseline in the vehicle group. Consequently, perivascular Po(2) was three times higher in the 5HMF group compared with the control group at 5% O(2) hypoxia. 5HMF also reduced heart and brain hypoxic areas in mice. Therefore, increased Hb O(2) affinity resulted in hemodynamics and oxygenation benefits during severe hypoxia. This acute acclimatization process may have implications in survival during severe environmental hypoxia when logistic constraints prevent chronic acclimatization. PMID:22636677

  14. Increased hemoglobin O2 affinity protects during acute hypoxia

    PubMed Central

    Yalcin, Ozlem

    2012-01-01

    Acclimatization to hypoxia requires time to complete the adaptation mechanisms that influence oxygen (O2) transport and O2 utilization. Although decreasing hemoglobin (Hb) O2 affinity would favor the release of O2 to the tissues, increasing Hb O2 affinity would augment arterial O2 saturation during hypoxia. This study was designed to test the hypothesis that pharmacologically increasing the Hb O2 affinity will augment O2 transport during severe hypoxia (10 and 5% inspired O2) compared with normal Hb O2 affinity. RBC Hb O2 affinity was increased by infusion of 20 mg/kg of 5-hydroxymethyl-2-furfural (5HMF). Control animals received only the vehicle. The effects of increasing Hb O2 affinity were studied in the hamster window chamber model, in terms of systemic and microvascular hemodynamics and partial pressures of O2 (Po2). Pimonidazole binding to hypoxic areas of mice heart and brain was also studied. 5HMF decreased the Po2 at which the Hb is 50% saturated with O2 by 12.6 mmHg. During 10 and 5% O2 hypoxia, 5HMF increased arterial blood O2 saturation by 35 and 48% from the vehicle group, respectively. During 5% O2 hypoxia, blood pressure and heart rate were 58 and 30% higher for 5HMF compared with the vehicle. In addition, 5HMF preserved microvascular blood flow, whereas blood flow decreased to 40% of baseline in the vehicle group. Consequently, perivascular Po2 was three times higher in the 5HMF group compared with the control group at 5% O2 hypoxia. 5HMF also reduced heart and brain hypoxic areas in mice. Therefore, increased Hb O2 affinity resulted in hemodynamics and oxygenation benefits during severe hypoxia. This acute acclimatization process may have implications in survival during severe environmental hypoxia when logistic constraints prevent chronic acclimatization. PMID:22636677

  15. International hypoxia symposium XVIII: 26 February–02 March 2013

    PubMed Central

    2013-01-01

    The 18th International Hypoxia Symposia, Lake Louise, Alberta, Canada, February 26–March 02, 2013, covered molecular basis of hypoxic responses (e.g., hypoxia inducible factor, nitrite, nitrate, and hemoglobin) and integrative physiology (e.g., exercise physiology, cerebral blood flow responses, live-high train-low, and population genetics). Free communications and poster sessions covered scientific areas from controlled lab settings to field settings of high altitudes (Andes to Himalayas). PMID:24229461

  16. Glycogen metabolism in rat heart muscle cultures after hypoxia.

    PubMed

    Vigoda, Ayelet; Mamedova, Liaman K; Shneyvays, Vladimir; Katz, Abram; Shainberg, Asher

    2003-12-01

    Elevated glycogen levels in heart have been shown to have cardioprotective effects against ischemic injury. We have therefore established a model for elevating glycogen content in primary rat cardiac cells grown in culture and examined potential mechanisms for the elevation (glycogen supercompensation). Glycogen was depleted by exposing the cells to hypoxia for 2 h in the absence of glucose in the medium. This was followed by incubating the cells with 28 mM glucose in normoxia for up to 120 h. Hypoxia decreased glycogen content to about 15% of control, oxygenated cells. This was followed by a continuous increase in glycogen in the hypoxia treated cells during the 120 h recovery period in normoxia. By 48 h after termination of hypoxia, the glycogen content had returned to baseline levels and by 120 h glycogen was about 150% of control. The increase in glycogen at 120 h was associated with comparable relative increases in glucose uptake (approximately 180% of control) and the protein level of the glut-1 transporter (approximately 170% of control), whereas the protein level of the glut-4 transporter was decreased to < 10% of control. By 120 h, the hypoxia-treated cells also exhibited marked increases in the total (approximately 170% of control) and fractional activity of glycogen synthase (control, approximately 15%; hypoxia-treated, approximately 30%). Concomitantly, the hypoxia-treated cells also exhibited marked decreases in the total (approximately 50% of control) and fractional activity of glycogen phosphorylase (control, approximately 50%; hypoxia-treated, approximately 25%). Thus, we have established a model of glycogen supercompensation in cultures of cardiac cells that is explained by concerted increases in glucose uptake and glycogen synthase activity and decreases in phosphorylase activity. This model should prove useful in studying the cardioprotective effects of glycogen. PMID:14674711

  17. Intrinsic and acquired resistance mechanisms in enterococcus

    PubMed Central

    Hollenbeck, Brian L.; Rice, Louis B.

    2012-01-01

    Enterococci have the potential for resistance to virtually all clinically useful antibiotics. Their emergence as important nosocomial pathogens has coincided with increased expression of antimicrobial resistance by members of the genus. The mechanisms underlying antibiotic resistance in enterococci may be intrinsic to the species or acquired through mutation of intrinsic genes or horizontal exchange of genetic material encoding resistance determinants. This paper reviews the antibiotic resistance mechanisms in Enterococcus faecium and Enterococcus faecalis and discusses treatment options. PMID:23076243

  18. The intrinsic resistome of bacterial pathogens

    PubMed Central

    Olivares, Jorge; Bernardini, Alejandra; Garcia-Leon, Guillermo; Corona, Fernando; B. Sanchez, Maria; Martinez, Jose L.

    2013-01-01

    Intrinsically resistant bacteria have emerged as a relevant health problem in the last years. Those bacterial species, several of them with an environmental origin, present naturally low-level susceptibility to several drugs. It has been proposed that intrinsic resistance is mainly the consequence of the impermeability of cellular envelopes, the activity of multidrug efflux pumps or the lack of appropriate targets for a given family of drugs. However, recently published articles indicate that the characteristic phenotype of susceptibility to antibiotics of a given bacterial species depends on the concerted activity of several elements, what has been named as intrinsic resistome. These determinants comprise not just classical resistance genes. Other elements, several of them involved in basic bacterial metabolic processes, are of relevance for the intrinsic resistance of bacterial pathogens. In the present review we analyze recent publications on the intrinsic resistomes of Escherichia coli and Pseudomonas aeruginosa. We present as well information on the role that global regulators of bacterial metabolism, as Crc from P. aeruginosa, may have on modulating bacterial susceptibility to antibiotics. Finally, we discuss the possibility of searching inhibitors of the intrinsic resistome in the aim of improving the activity of drugs currently in use for clinical practice. PMID:23641241

  19. The Effect of Hypoxia on Mesenchymal Stem Cell Biology

    PubMed Central

    Ejtehadifar, Mostafa; Shamsasenjan, Karim; Movassaghpour, Aliakbar; Akbarzadehlaleh, Parvin; Dehdilani, Nima; Abbasi, Parvaneh; Molaeipour, Zahra; Saleh, Mahshid

    2015-01-01

    Although physiological and pathological role of hypoxia have been appreciated in mammalians for decades however the cellular biology of hypoxia more clarified in the past 20 years. Discovery of the transcription factor hypoxia-inducible factor (HIF)-1, in the 1990s opened a new window to investigate the mechanisms behind hypoxia. In different cellular contexts HIF-1 activation show variable results by impacting various aspects of cell biology such as cell cycle, apoptosis, differentiation and etc. Mesenchymal stem cells (MSC) are unique cells which take important role in tissue regeneration. They are characterized by self-renewal capacity, multilineage potential, and immunosuppressive property. Like so many kind of cells, hypoxia induces different responses in MSCs by HIF- 1 activation. The activation of this molecule changes the growth, multiplication, differentiation and gene expression profile of MSCs in their niche by a complex of signals. This article briefly discusses the most important effects of hypoxia in growth kinetics, signalling pathways, cytokine secretion profile and expression of chemokine receptors in different conditions. PMID:26236651

  20. Mesenchymal Stem Cells Respond to Hypoxia by Increasing Diacylglycerols.

    PubMed

    Lakatos, Kinga; Kalomoiris, Stefanos; Merkely, Béla; Nolta, Jan A; Fierro, Fernando A

    2016-02-01

    Mesenchymal stem cells (MSC) are currently being tested clinically for a plethora of conditions, with most approaches relying on the secretion of paracrine signals by MSC to modulate the immune system, promote wound healing, and induce angiogenesis. Hypoxia has been shown to affect MSC proliferation, differentiation, survival and secretory profile. Here, we investigate changes in the lipid composition of human bone marrow-derived MSC after exposure to hypoxia. Using mass spectrometry, we compared the lipid profiles of MSC derived from five different donors, cultured for two days in either normoxia (control) or hypoxia (1% oxygen). Hypoxia induced a significant increase of total triglycerides, fatty acids and diacylglycerols (DG). Remarkably, reduction of DG levels using the phosphatidylcholine-specific phospholipase C inhibitor D609 inhibited the secretion of VEGF and Angiopoietin-2, but increased the secretion of interleukin-8, without affecting significantly their respective mRNA levels. Functionally, incubation of MSC in hypoxia with D609 inhibited the potential of the cells to promote migration of human endothelial cells in a wound/scratch assay. Hence, we show that hypoxia induces in MSC an increase of DG that may affect the angiogenic potential of these cells. PMID:26212931

  1. PET imaging of cardiac hypoxia: Opportunities and challenges

    PubMed Central

    Handley, M.G.; Medina, R.A.; Nagel, E.; Blower, P.J.; Southworth, R.

    2012-01-01

    Myocardial hypoxia is a major factor in the pathology of cardiac ischemia and myocardial infarction. Hypoxia also occurs in microvascular disease and cardiac hypertrophy, and is thought to be a prime determinant of the progression to heart failure, as well as the driving force for compensatory angiogenesis. The non-invasive delineation and quantification of hypoxia in cardiac tissue therefore has the potential to be an invaluable experimental, diagnostic and prognostic biomarker for applications in cardiology. However, at this time there are no validated methodologies sufficiently sensitive or reliable for clinical use. PET imaging provides real-time spatial information on the biodistribution of injected radiolabeled tracer molecules. Its inherent high sensitivity allows quantitative imaging of these tracers, even when injected at sub-pharmacological (≥pM) concentrations, allowing the non-invasive investigation of biological systems without perturbing them. PET is therefore an attractive approach for the delineation and quantification of cardiac hypoxia and ischemia. In this review we discuss the key concepts which must be considered when imaging hypoxia in the heart. We summarize the PET tracers which are currently available, and we look forward to the next generation of hypoxia-specific PET imaging agents currently being developed. We describe their potential advantages and shortcomings compared to existing imaging approaches, and what is needed in terms of validation and characterization before these agents can be exploited clinically. PMID:21781973

  2. Pronounced kidney hypoxia precedes albuminuria in type 1 diabetic mice.

    PubMed

    Franzén, Stephanie; Pihl, Liselotte; Khan, Nadeem; Gustafsson, Håkan; Palm, Fredrik

    2016-05-01

    Intrarenal tissue hypoxia has been proposed as a unifying mechanism for the development of chronic kidney disease, including diabetic nephropathy. However, hypoxia has to be present before the onset of kidney disease to be the causal mechanism. To establish whether hypoxia precedes the onset of diabetic nephropathy, we implemented a minimally invasive electron paramagnetic resonance oximetry technique using implanted oxygen sensing probes for repetitive measurements of in vivo kidney tissue oxygen tensions in mice. Kidney cortex oxygen tensions were measured before and up to 15 days after the induction of insulinopenic diabetes in male mice and compared with normoglycemic controls. On day 16, urinary albumin excretions and conscious glomerular filtration rates were determined to define the temporal relationship between intrarenal hypoxia and disease development. Diabetic mice developed pronounced intrarenal hypoxia 3 days after the induction of diabetes, which persisted throughout the study period. On day 16, diabetic mice had glomerular hyperfiltration, but normal urinary albumin excretion. In conclusion, intrarenal tissue hypoxia in diabetes precedes albuminuria thereby being a plausible cause for the onset and progression of diabetic nephropathy. PMID:26936871

  3. The tumour hypoxia induced non-coding transcriptome.

    PubMed

    Choudhry, Hani; Harris, Adrian L; McIntyre, Alan

    2016-01-01

    Recent investigations have highlighted the importance of the non-coding genome in regions of hypoxia in tumours. Such regions are frequently found in solid tumours, and are associated with worse patient survival and therapy resistance. Hypoxia stabilises the transcription factors, hypoxia inducible factors (HIF1α and HIF2α) which coordinate transcriptomic changes that occur in hypoxia. The changes in gene expression induced by HIF1α and HIF2α contribute to many of the hallmarks of cancer phenotypes and enable tumour growth, survival and invasion in the hypoxic tumour microenvironment. Non-coding RNAs, in particular microRNAs (miRNAs), which regulate mRNA stability and translation, and long-non-coding RNAs (lncRNAs), which have diverse functions including chromatin modification and transcriptional regulation, are also important in enabling the key hypoxia regulated processes. They have roles in the regulation of metabolism, angiogenesis, autophagy, invasion and metastasis in the hypoxic microenvironment. Furthermore, HIF1α and HIF2α expression and stabilisation are also regulated by both miRNAs and lncRNAs. Here we review the recent developments in the expression, regulation and functions of miRNAs, lncRNAs and other non-coding RNA classes in tumour hypoxia. PMID:26806607

  4. HYPOXIA IN THE NORTHERN GULF OF MEXICO: DOES THE SCIENCE SUPPORT THE PLAN TO REDUCE, MITIGATE, AND CONTROL HYPOXIA?

    EPA Science Inventory

    We update and reevaluate the scientific information on the distribution, history and causes of continental shelf hypoxia that supports the 2001 "Action Plan for Reducing, Mitigating, and Controlling Hypoxiain the Northern Gulf of Mexico," incorporating data, publications, and res...

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

    PubMed Central

    2010-01-01

    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. PMID:20637078

  6. Hypoxia Precondition Promotes Adipose-Derived Mesenchymal Stem Cells Based Repair of Diabetic Erectile Dysfunction via Augmenting Angiogenesis and Neuroprotection

    PubMed Central

    Li, ShaoDan; Xu, Yong; Chen, Ping; Liu, Yi; Ding, Qiang; Wahafu, Wasilijiang; Hong, BaoFa; Yang, MingHui

    2015-01-01

    The aim of the present study was to examine whether hypoxia preconditioning could improve therapeutic effects of adipose derived mesenchymal stem cells (AMSCs) for diabetes induced erectile dysfunction (DED). AMSCs were pretreated with normoxia (20% O2, N-AMSCs) or sub-lethal hypoxia (1% O2, H-AMSCs). The hypoxia exposure up-regulated the expression of several angiogenesis and neuroprotection related cytokines in AMSCs, including vascular endothelial growth factor (VEGF) and its receptor FIK-1, angiotensin (Ang-1), basic fibroblast growth factor (bFGF), brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), stromal derived factor-1 (SDF-1) and its CXC chemokine receptor 4 (CXCR4). DED rats were induced via intraperitoneal injection of streptozotocin (60 mg/kg) and were randomly divided into three groups—Saline group: intracavernous injection with phosphate buffer saline; N-AMSCs group: N-AMSCs injection; H-AMSCs group: H-AMSCs injection. Ten rats without any treatment were used as normal control. Four weeks after injection, the mean arterial pressure (MAP) and intracavernosal pressure (ICP) were measured. The contents of endothelial, smooth muscle, dorsal nerve in cavernoursal tissue were assessed. Compared with N-AMSCs and saline, intracavernosum injection of H-AMSCs significantly raised ICP and ICP/MAP (p<0.05). Immunofluorescent staining analysis demonstrated that improved erectile function by MSCs was significantly associated with increased expression of endothelial markers (CD31 and vWF) (p<0.01) and smooth muscle markers (α-SMA) (p<0.01). Meanwhile, the expression of nNOS was also significantly higher in rats receiving H-AMSCs injection than those receiving N-AMSCs or saline injection. The results suggested that hypoxic preconditioning of MSCs was an effective approach to enhance their therapeutic effect for DED, which may be due to their augmented angiogenesis and neuroprotection. PMID:25790284

  7. Reactions of human and hog intrinsic factors with type I antibody to intrinsic factor

    PubMed Central

    Gullberg, R.

    1970-01-01

    A simple and rapid small-scale gel filtration method was applied in studies of type I antibody to intrinsic factor using radioactive vitamin B12 of high specific activity and purified human and hog intrinsic factor preparations, taking into account the unsaturated B12-binding capacity of the individual pernicious anaemia sera. This procedure allows the use of small amounts of reagents. Evidence was obtained for a close antigenic similarity of determinants of human and hog intrinsic factor. The use of purified intrinsic-factor preparations is important. PMID:4097742

  8. A novel family of fluorescent hypoxia sensors reveal strong heterogeneity in tumor hypoxia at the cellular level.

    PubMed

    Erapaneedi, Raghu; Belousov, Vsevolod V; Schäfers, Michael; Kiefer, Friedemann

    2016-01-01

    Hypoxia is an intensively investigated condition with profound effects on cell metabolism, migration, and angiogenesis during development and disease. Physiologically, hypoxia is linked to tissue homeostasis and maintenance of pluripotency. Hypoxia also contributes to pathologies including cardiovascular diseases and cancer. Despite its importance, microscopic visualization of hypoxia is largely restricted to the detection of reductively activated probes by immunostaining. Here, we describe a novel family of genetically encoded fluorescent sensors that detect the activation of HIF transcription factors reported by the oxygen-independent fluorescent protein UnaG. It comprises sensors with different switching and memory behavior and combination sensors that allow the distinction of hypoxic and reoxygenated cells. We tested these sensors on orthotopically transplanted glioma cell lines. Using a cranial window, we could visualize hypoxia intravitally at cellular resolution. In tissue samples, sensor activity was detected in regions, which were largely devoid of blood vessels, correlated with HIF-1α stabilization, and were highly heterogeneous at a cellular level. Frequently, we detected recently reoxygenated cells outside hypoxic areas in the proximity of blood vessels, suggestive of hypoxia-promoted cell migration. PMID:26598532

  9. Induction of WNT11 by hypoxia and hypoxia-inducible factor-1α regulates cell proliferation, migration and invasion

    PubMed Central

    Mori, Hiroyuki; Yao, Yao; Learman, Brian S.; Kurozumi, Kazuhiko; Ishida, Joji; Ramakrishnan, Sadeesh K.; Overmyer, Katherine A.; Xue, Xiang; Cawthorn, William P.; Reid, Michael A.; Taylor, Matthew; Ning, Xiaomin; Shah, Yatrik M.; MacDougald, Ormond A.

    2016-01-01

    Changes in cellular oxygen tension play important roles in physiological processes including development and pathological processes such as tumor promotion. The cellular adaptations to sustained hypoxia are mediated by hypoxia-inducible factors (HIFs) to regulate downstream target gene expression. With hypoxia, the stabilized HIF-α and aryl hydrocarbon receptor nuclear translocator (ARNT, also known as HIF-β) heterodimer bind to hypoxia response elements (HREs) and regulate expression of target genes. Here, we report that WNT11 is induced by hypoxia in many cell types, and that transcription of WNT11 is regulated primarily by HIF-1α. We observed induced WNT11 expression in the hypoxic area of allograft tumors. In addition, in mice bearing orthotopic malignant gliomas, inhibition with bevacizumab of vascular endothelial growth factor, which is an important stimulus for angiogenesis, increased nuclear HIF-1α and HIF-2α, and expression of WNT11. Gain- and loss-of-function approaches revealed that WNT11 stimulates proliferation, migration and invasion of cancer-derived cells, and increases activity of matrix metalloproteinase (MMP)-2 and 9. Since tumor hypoxia has been proposed to increase tumor aggressiveness, these data suggest WNT11 as a possible target for cancer therapies, especially for tumors treated with antiangiogenic therapy. PMID:26861754

  10. Gene expression promoted by the SV40 DNA targeting sequence and the hypoxia-responsive element under normoxia and hypoxia.

    PubMed

    Sacramento, C B; Moraes, J Z; Denapolis, P M A; Han, S W

    2010-08-01

    The main objective of the present study was to find suitable DNA-targeting sequences (DTS) for the construction of plasmid vectors to be used to treat ischemic diseases. The well-known Simian virus 40 nuclear DTS (SV40-DTS) and hypoxia-responsive element (HRE) sequences were used to construct plasmid vectors to express the human vascular endothelial growth factor gene (hVEGF). The rate of plasmid nuclear transport and consequent gene expression under normoxia (20% O2) and hypoxia (less than 5% O2) were determined. Plasmids containing the SV40-DTS or HRE sequences were constructed and used to transfect the A293T cell line (a human embryonic kidney cell line) in vitro and mouse skeletal muscle cells in vivo. Plasmid transport to the nucleus was monitored by real-time PCR, and the expression level of the hVEGF gene was measured by ELISA. The in vitro nuclear transport efficiency of the SV40-DTS plasmid was about 50% lower under hypoxia, while the HRE plasmid was about 50% higher under hypoxia. Quantitation of reporter gene expression in vitro and in vivo, under hypoxia and normoxia, confirmed that the SV40-DTS plasmid functioned better under normoxia, while the HRE plasmid was superior under hypoxia. These results indicate that the efficiency of gene expression by plasmids containing DNA binding sequences is affected by the concentration of oxygen in the medium. PMID:20640386

  11. Hypoxia in tumors: pathogenesis-related classification, characterization of hypoxia subtypes, and associated biological and clinical implications.

    PubMed

    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. PMID:24729210

  12. ADAPTIVE AND MALADAPTIVE CARDIORESPIRATORY RESPONSES TO CONTINUOUS AND INTERMITTENT HYPOXIA MEDIATED BY HYPOXIA-INDUCIBLE FACTORS 1 AND 2

    PubMed Central

    Prabhakar, Nanduri R.; Semenza, Gregg L.

    2014-01-01

    Hypoxia is a fundamental stimulus that impacts cells, tissues, organs, and physiological systems. The discovery of hypoxia-inducible factor-1 (HIF-1) and subsequent identification of other members of the HIF family of transcriptional activators has provided insight into the molecular underpinnings of oxygen homeostasis. This review focuses on the mechanisms of HIF activation and their roles in physiological and pathophysiological responses to hypoxia, with an emphasis on the cardiorespiratory systems. HIFs are heterodimers comprised of an O2-regulated HIF-1α or HIF-2α subunit and a constitutively expressed HIF-1β subunit. Induction of HIF activity under conditions of reduced O2 availability requires stabilization of HIF-1α and HIF-2α due to reduced prolyl hydroxylation, dimerization with HIF-1β, and interaction with coactivators due to decreased asparaginyl hydroxylation. Stimuli other than hypoxia, such as nitric oxide and reactive oxygen species, can also activate HIFs. HIF-1 and HIF-2 are essential for acute O2 sensing by the carotid body, and their coordinated transcriptional activation is critical for physiological adaptations to chronic hypoxia including erythropoiesis, vascularization, metabolic reprogramming, and ventilatory acclimatization. In contrast, intermittent hypoxia, which occurs in association with sleep-disordered breathing, results in an imbalance between HIF-1α and HIF-2α that causes oxidative stress, leading to cardiorespiratory pathology. PMID:22811423

  13. URG11 mediates hypoxia-induced epithelial-to-mesenchymal transition by modulation of E-cadherin and {beta}-catenin

    SciTech Connect

    Du, Rui; Huang, Chen; Bi, Qian; Zhai, Ying; Xia, Lin; Liu, Jie; Sun, Shiren; Fan, Daiming

    2010-01-01

    Upregulated gene 11 (URG11), recently identified as a new HBx-upregulated gene that may activate {beta}-catenin and Wnt signaling, was found to be upregulated in a human tubule cell line under low oxygen. Here, we investigated the potential role of URG11 in hypoxia-induced renal tubular epithelial-to-mesenchymal (EMT). Overexpression of URG11 in a human proximal tubule cell line (HK2) promoted a mesenchymal phenotype accompanied by reduced expression of the epithelial marker E-cadherin and increased expression of the mesenchymal markers vimentin and {alpha}-SMA, while URG11 knockdown by siRNA effectively reversed hypoxia-induced EMT. URG11 promoted the expression of {beta}-catenin and increased its nuclear accumulation under normoxic conditions through transactivation of the {beta}-catenin promoter. This in turn upregulated {beta}-catenin/T-cell factor (TCF) and its downstream effector genes, vimentin, and {alpha}-SMA. In vivo, strong expression of URG11 was observed in the tubular epithelia of 5/6-nephrectomized rats, and a Western blot analysis demonstrated a close correlation between HIF-1{alpha} and URG11 protein levels. Altogether, our results indicate that URG11 mediates hypoxia-induced EMT through the suppression of E-cadherin and the activation of the {beta}-catenin/TCF pathway.

  14. Distinct Regulatory Mechanisms of the Human Ferritin Gene by Hypoxia and Hypoxia Mimetic Cobalt Chloride at the Transcriptional and Post-transcriptional Levels

    PubMed Central

    Huang, Bo-Wen; Miyazawa, Masaki; Tsuji, Yoshiaki

    2014-01-01

    Cobalt chloride has been used as a hypoxia mimetic because it stabilizes hypoxia inducible factor-1α (HIF1-α) and activates gene transcription through a hypoxia responsive element (HRE). However, differences between hypoxia and hypoxia mimetic cobalt chloride in gene regulation remain elusive. Expression of ferritin, the major iron storage protein, is regulated at the transcriptional and posttranscriptional levels through DNA and RNA regulatory elements. Here we demonstrate that hypoxia and cobalt chloride regulate ferritin heavy chain (ferritin H) expression by two distinct mechanisms. Both hypoxia and cobalt chloride increased HIF1-α but a putative HRE in the human ferritin H gene was not activated. Instead, cobalt chloride but not hypoxia activated ferritin H transcription through an antioxidant responsive element (ARE), to which Nrf2 was recruited. Intriguingly, cobalt chloride downregulated ferritin H protein expression while upregulated other ARE-regulated antioxidant genes in K562 cells. Further characterization demonstrated that cobalt chloride increased interaction between iron regulatory proteins (IRP1 and IRP2) and iron responsive element (IRE) in the 5′UTR of ferritin H mRNA, resulting in translational block of the accumulated ferritin H mRNA. In contrast, hypoxia had marginal effect on ferritin H transcription but increased its translation through decreased IRP1-IRE interaction. These results suggest that hypoxia and hypoxia mimetic cobalt chloride employ distinct regulatory mechanisms through the interplay between DNA and mRNA elements at the transcriptional and post-transcriptional levels. PMID:25172425

  15. Intrinsic delay of permeable base transistor

    SciTech Connect

    Chen, Wenchao; Guo, Jing; So, Franky

    2014-07-28

    Permeable base transistors (PBTs) fabricated by vacuum deposition or solution process have the advantages of easy fabrication and low power operation and are a promising device structure for flexible electronics. Intrinsic delay of PBT, which characterizes the speed of the transistor, is investigated by solving the three-dimensional Poisson equation and drift-diffusion equation self-consistently using finite element method. Decreasing the emitter thickness lowers the intrinsic delay by improving on-current, and a thinner base is also preferred for low intrinsic delay because of fewer carriers in the base region at off-state. The intrinsic delay exponentially decreases as the emitter contact Schottky barrier height decreases, and it linearly depends on the carrier mobility. With an optimized emitter contact barrier height and device geometry, a sub-nano-second intrinsic delay can be achieved with a carrier mobility of ∼10 cm{sup 2}/V/s obtainable in solution processed indium gallium zinc oxide, which indicates the potential of solution processed PBTs for GHz operations.

  16. Apelin as a marker for monitoring the tumor vessel normalization window during antiangiogenic therapy.

    PubMed

    Zhang, Li; Takara, Kazuhiro; Yamakawa, Daishi; Kidoya, Hiroyasu; Takakura, Nobuyuki

    2016-01-01

    Antiangiogenic agents transiently normalize tumor vessel structure and improve vessel function, thereby providing a window of opportunity for enhancing the efficacy of chemotherapy or radiotherapy. Currently, there are no reliable predictors or markers reflecting this vessel normalization window during antiangiogenic therapy. Apelin, the expression of which is regulated by hypoxia, and which has well-described roles in tumor progression, is an easily measured secreted protein. Here, we show that apelin can be used as a marker for the vessel normalization window during antiangiogenic therapy. Mice bearing s.c. tumors resulting from inoculation of the colon adenocarcinoma cell line HT29 were treated with a single injection of bevacizumab, a mAb neutralizing vascular endothelial growth factor. Tumor growth, vessel density, pericyte coverage, tumor hypoxia, and small molecule delivery were determined at four different times after treatment with bevacizumab (days 1, 3, 5, and 8). Tumor growth and vessel density were significantly reduced after bevacizumab treatment, which also significantly increased tumor vessel maturity, and improved tumor hypoxia and small molecule delivery between days 3 and 5. These effects abated by day 8, suggesting that a time window for vessel normalization was opened between days 3 and 5 during bevacizumab treatment in this model. Apelin mRNA expression and plasma apelin levels decreased transiently at day 5 post-treatment, coinciding with vessel normalization. Thus, apelin is a potential indicator of the vessel normalization window during antiangiogenic therapy. PMID:26475217

  17. Nutritional status in chronic obstructive pulmonary disease: role of hypoxia.

    PubMed

    Raguso, Comasia A; Luthy, Christophe

    2011-02-01

    In patients with chronic obstructive pulmonary disease (COPD), malnutrition and limited physical activity are very common and contribute to disease prognosis, whereas a balance between caloric intake and exercise allows body weight stability and muscle mass preservation. The goal of this review is to analyze the implications of chronic hypoxia on three key elements involved in energy homeostasis and its role in COPD cachexia. The first one is energy intake. Body weight loss, often observed in patients with COPD, is related to lack of appetite. Inflammatory cytokines are known to be involved in anorexia and to be correlated to arterial partial pressure of oxygen. Recent studies in animals have investigated the role of hypoxia in peptides involved in food consumption such as leptin, ghrelin, and adenosine monophosphate activated protein kinase. The second element is muscle function, which is strongly related to energy use. In COPD, muscle atrophy and muscle fiber shift to the glycolytic type might be an adaptation to chronic hypoxia to preserve the muscle from oxidative stress. Muscle atrophy could be the result of a marked activation of the ubiquitin-proteasome pathway as found in muscle of patients with COPD. Hypoxia, via hypoxia inducible factor-1, is implicated in mitochondrial biogenesis and autophagy. Third, hormonal control of energy balance seems to be affected in patients with COPD. Insulin resistance has been described in this group of patients as well as a sort of "growth hormone resistance." Hypoxia, by hypoxia inducible factor-1, accelerates the degradation of tri-iodothyronine and thyroxine, decreasing cellular oxygen consumption, suggesting an adaptive mechanism rather than a primary cause of COPD cachexia. COPD rehabilitation aimed at maintaining function and quality of life needs to address body weight stabilization and, in particular, muscle mass preservation. PMID:21145207

  18. Informativeness of microsatellite markers.

    PubMed

    Reyes-Valdés, M Humberto

    2013-01-01

    Simple sequence repeats (SSR) are extensively used as genetic markers for studies of diversity, genetic mapping, and cultivar discrimination. The informativeness of a given SSR locus or a loci group depends on the number of alleles, their frequency distribution, as well as the kind of application. Here I describe several methods for calculating marker informativeness, all of them suitable for SSR polymorphisms, proposed by several authors and synthesized in an Information Theory framework. Additionally, free access software resources are described as well as their application through worked examples. PMID:23546797

  19. Relaxin Protects Astrocytes from Hypoxia In Vitro

    PubMed Central

    Willcox, Jordan M.; Summerlee, Alastair J. S.

    2014-01-01

    The peptide relaxin has recently been shown to protect brain tissues from the detrimental effects of ischemia. To date, the mechanisms for this remain unclear. In order to investigate the neuroprotective mechanisms by which relaxin may protect the brain, we investigated the possibility that relaxin protects astrocytes from hypoxia or oxygen/glucose deprivation (OGD). Cultured astrocytes were pre-treated with either relaxin-2 or relaxin-3 and exposed to OGD for 24 or 48 hours. Following OGD exposure, viability assays showed that relaxin-treated cells exhibited a higher viability when compared to astrocytes that experienced OGD-alone. Next, to test whether relaxin reduced the production of reactive oxygen species (ROS) astrocytes were exposed to the same conditions as the previous experiment and a commercially available ROS detection kit was used to detect ROS production. Astrocytes that were treated with relaxin-2 and relaxin-3 showed a marked decrease in ROS production when compared to control astrocytes that were exposed only to OGD. Finally, experiments were performed to determine whether or not the mitochondrial membrane potential was affected by relaxin treatment during 24 hour OGD. Mitochondrial membrane potential was higher in astrocytes that were treated with relaxin-2 and relaxin-3 compared to untreated OGD-alone astrocytes. Taken together, these data present novel findings that show relaxin protects astrocytes from ischemic conditions through the reduction of ROS production and the maintenance of mitochondrial membrane potential. PMID:24598861

  20. PH2O and simulated hypobaric hypoxia.

    PubMed

    Conkin, Johnny

    2011-12-01

    Some manufacturers of reduced oxygen (O2) breathing devices claim a comparable hypobaric hypoxia (HH) training experience by providing F1O2 < 0.209 at or near sea level pressure to match the ambient oxygen partial pressure (iso-PO2) of the target altitude. I conclude after a review of literature from investigators and manufacturers that these devices may not properly account for the 47 mmHg of water vapor partial pressure that reduces the inspired partial pressure of oxygen (P1O2), which is substantial at higher altitude relative to sea level. Consequently, some devices claiming an equivalent HH experience under normobaric conditions would significantly overestimate the HH condition, especially when simulating altitudes above 10,000 ft (3048 m). At best, the claim should be that the devices provide an approximate HH experience since they only duplicate the ambient PO2 at sea level as at altitude. An approach to reduce the overestimation and standardize the operation is to at least provide machines that create the same P1O2 conditions at sea level as at the target altitude, a simple software upgrade. PMID:22195399

  1. The cerebral venous system and hypoxia.

    PubMed

    Wilson, Mark H; Imray, Christopher H E

    2016-01-15

    Most hypobaric hypoxia studies have focused on oxygen delivery and therefore cerebral blood inflow. Few have studied venous outflow. However, the volume of blood entering and leaving the skull (∼700 ml/min) is considerably greater than cerebrospinal fluid production (0.35 ml/min) or edema formation rates and slight imbalances of in- and outflow have considerable effects on intracranial pressure. This dynamic phenomenon is not necessarily appreciated in the currently taught static "Monro-Kellie" doctrine, which forms the basis of the "Tight-Fit" hypothesis thought to underlie high altitude headache, acute mountain sickness, and high altitude cerebral edema. Investigating both sides of the cerebral circulation was an integral part of the 2007 Xtreme Everest Expedition. The results of the relevant studies performed as part of and subsequent to this expedition are reviewed here. The evidence from recent studies suggests a relative venous outflow insufficiency is an early step in the pathogenesis of high altitude headache. Translation of knowledge gained from high altitude studies is important. Many patients in a critical care environment develop hypoxemia akin to that of high altitude exposure. An inability to drain the hypoxemic induced increase in cerebral blood flow could be an underappreciated regulatory mechanism of intracranial pressure. PMID:26294747

  2. Genome-Wide Prediction of Intrinsic Disorder; Sequence Alignment of Intrinsically Disordered Proteins

    ERIC Educational Resources Information Center

    Midic, Uros

    2012-01-01

    Intrinsic disorder (ID) is defined as a lack of stable tertiary and/or secondary structure under physiological conditions in vitro. Intrinsically disordered proteins (IDPs) are highly abundant in nature. IDPs possess a number of crucial biological functions, being involved in regulation, recognition, signaling and control, e.g. their functional…

  3. Intrinsic innervation and dopaminergic markers after experimental denervation in rat thymus

    PubMed Central

    Mignini, F.; Sabbatini, M.; D'Andrea, V.; Cavallotti, C.

    2010-01-01

    The aim of this study was to examine rat thymus innervation using denervation techniques and to explore the related microanatomical localization of dopamine, D1, D2 receptors and dopamine membrane transporter (DAT). In the thymus subcapsular region, the parenchymal cholinergic fibers belong exclusively to phrenic nerve branching. No somatic phrenic nerve branching was detected in any other analysed thymus lobule regions. In rats subjected to sympathetic or parasympathetic ablation, it was observed that catecholaminergic and cholinergic nerve fibers respectively contributed to forming plexuses along vessel walls. In the subcapsular and septal region, no parenchymal nerve branching, belonging to sympathetic or parasympathetic nervous system was noted. Instead, in the deep cortical region, cortico-medullary junction (CM-j) and medulla, catecholaminergic and cholinergic nerve fibers were detected along the vessels and parenchyma. Dopamine and dopamine receptors were widely diffused in the lobular cortico-medullary junction region and in the medulla, where the final steps of thymocyte maturation and their trafficking take place. No variation in dopamine and DAT immune reaction was observed following total or partial parasympathectomy or phrenic nerve cutting. After chemical or surgical sympathectomy however, neither dopamine nor DAT immune reaction was noted again. Instead, D1 and D2 dopamine receptor expression was not affected by thymus denervation. In rats subjected to specific denervation, it was observed the direct intraparenchymal branching of the phrenic nerve and sympathetic and parasympathetic fibers into thymus parenchyma along vessels. These findings on the dopaminergic system highlight the importance of neurotransmitter receptor expression in the homeostasis of neuroimmune modulation. PMID:20558339

  4. Hypoxia imaging predicts success of hypoxia-induced cytosine deaminase/5-fluorocytosine gene therapy in a murine lung tumor model.

    PubMed

    Lee, B-F; Lee, C-H; Chiu, N-T; Hsia, C-C; Shen, L-H; Shiau, A-L

    2012-04-01

    Tc-99m-HL91 is a hypoxia imaging biomarker. The aim of this study was to investigate the value of Tc-99m-HL91 imaging for hypoxia-induced cytosine deaminase (CD)/5-fluorocytosine (5-FC) gene therapy in a murine lung tumor model. C57BL/6 mice were implanted with Lewis lung carcinoma cells transduced with the hypoxia-inducible promoter-driven CD gene (LL2/CD) or luciferase gene (LL2/Luc) serving as the control. When tumor volumes reached 100 mm(3), pretreatment images were acquired after injection of Tc-99m-HL91. The mice were divided into low and high hypoxic groups based on the tumor-to-non-tumor ratio of Tc-99m-HL91. They were injected daily with 5-FC (500 mg kg(-1)) or the vehicle for 1 week. When tumor volumes reached 1000 mm(3), autoradiography and histological examinations were performed. Treatment with 5-FC delayed tumor growth and enhanced the survival of mice bearing high hypoxic LL2/CD tumors. The therapeutic effect of hypoxia-induced CD/5-FC gene therapy was more pronounced in high hypoxic tumors than in low hypoxic tumors. This study provides the first evidence that Tc-99m-HL91 can serve as an imaging biomarker for predicting the treatment responses of hypoxia-regulated CD/5-FC gene therapy in animal tumor models. Our results suggest that hypoxia imaging using Tc-99m-HL91 has the predictive value for the success of hypoxia-directed treatment regimens. PMID:22281757

  5. Kaposi's sarcoma-associated herpesvirus latency-associated nuclear antigen induction by hypoxia and hypoxia-inducible factors.

    PubMed

    Veeranna, Ravindra P; Haque, Muzammel; Davis, David A; Yang, Min; Yarchoan, Robert

    2012-01-01

    Hypoxia and hypoxia-inducible factors (HIFs) play an important role in the Kaposi's sarcoma-associated herpesvirus (KSHV) life cycle. In particular, hypoxia can activate lytic replication of KSHV and specific lytic genes, including the replication and transcription activator (RTA), while KSHV infection in turn can increase the levels and activity of HIFs. In the present study, we show that hypoxia increases the levels of mRNAs encoding KSHV latency-associated nuclear antigen (LANA) in primary effusion lymphoma (PEL) cell lines and also increases the levels of LANA protein. Luciferase reporter assays in Hep3B cells revealed a moderate activation of the LANA promoter region by hypoxia as well as by cotransfection with degradation-resistant HIF-1α or HIF-2α expression plasmids. Computer analysis of a 1.2-kb sequence upstream of the LANA translational start site identified six potential hypoxia-responsive elements (HRE). Sequential deletion studies revealed that much of this activity was mediated by one of these HREs (HRE 4R) oriented in the 3' to 5' direction and located between the constitutive (LTc) and RTA-inducible (LTi) mRNA start sites. Site-directed mutation of this HRE substantially reduced the response to both HIF-1α and HIF-2α in a luciferase reporter assay. Electrophoretic mobility shift assays (EMSA) and chromatin immunoprecipitation (ChIP) assays demonstrated binding of both HIF-1α and HIF-2α to this region. Also, HIF-1α was found to associate with RTA, and HIFs enhanced the activation of LTi by RTA. These results provide evidence that hypoxia and HIFs upregulate both latent and lytic KSHV replication and play a central role in the life cycle of this virus. PMID:22090111

  6. Intrinsic and extrinsic switching in molecular devices

    NASA Astrophysics Data System (ADS)

    van der Molen, Sense Jan; Trouwborst, Marius L.

    2015-01-01

    The details of metal-molecule coupling play a pivotal role in the functionality of molecular junctions. Molecules that have intrinsic switchable properties may lose this capability after coupling to electrodes. On the other hand, connecting passive molecules to electrodes may lead to a switchable molecular device ('extrinsic switching'). Here, we first discuss this general matter, and then focus on two specific cases, one of intrinsic switching (for photochromic diarylethenes) and one of extrinsic switching (for hydrogen molecules) in gold-molecule-gold structures.

  7. Bootstrapped models for intrinsic random functions

    SciTech Connect

    Campbell, K.

    1987-01-01

    The use of intrinsic random function stochastic models as a basis for estimation in geostatistical work requires the identification of the generalized covariance function of the underlying process, and the fact that this function has to be estimated from the data introduces an additional source of error into predictions based on the model. This paper develops the sample reuse procedure called the ''bootstrap'' in the context of intrinsic random functions to obtain realistic estimates of these errors. Simulation results support the conclusion that bootstrap distributions of functionals of the process, as well as of their ''kriging variance,'' provide a reasonable picture of the variability introduced by imperfect estimation of the generalized covariance function.

  8. Bootstrapped models for intrinsic random functions

    SciTech Connect

    Campbell, K.

    1988-08-01

    Use of intrinsic random function stochastic models as a basis for estimation in geostatistical work requires the identification of the generalized covariance function of the underlying process. The fact that this function has to be estimated from data introduces an additional source of error into predictions based on the model. This paper develops the sample reuse procedure called the bootstrap in the context of intrinsic random functions to obtain realistic estimates of these errors. Simulation results support the conclusion that bootstrap distributions of functionals of the process, as well as their kriging variance, provide a reasonable picture of variability introduced by imperfect estimation of the generalized covariance function.

  9. Effect of Organic Enrichment and Hypoxia on the Biodiversity of Benthic Communities in Narragansett Bay

    EPA Science Inventory

    Excessive input of nitrogen to coastal waters leads to eutrophication and hypoxia that reduce biodiversity and impair key ecosystem services provided by benthic communities; for example, fish and shellfish production, bioturbation, nutrient cycling, and water filtration. Hypoxia ...

  10. Effects of Hypoxia on Animal Burrow Construction and Consequent Effects on Sediment Redox Profiles

    EPA Science Inventory

    Previous studies investigating the effects of hypoxia on benthic infauna and consequent effects on sediment chemistry provide only correlative results from the field. In order to establish causation and isolate effects of hypoxia on individual species, we conducted a laboratory ...

  11. Strategy Markers in Writing.

    ERIC Educational Resources Information Center

    Sindermann, Gerda; Horsella, Maria

    1989-01-01

    Part of a research project is presented that aims at identifying the difficulties tertiary level students encounter in reading scientific texts in a foreign language and the strategies they apply to overcome them. Strategy markers are identified and listed, and are then analyzed to interpret the linguistic difficulty and the strategy used.…

  12. The Swift Turbidity Marker

    ERIC Educational Resources Information Center

    Omar, Ahmad Fairuz; MatJafri, Mohd Zubir

    2011-01-01

    The Swift Turbidity Marker is an optical instrument developed to measure the level of water turbidity. The components and configuration selected for the system are based on common turbidity meter design concepts but use a simplified methodology to produce rapid turbidity measurements. This work is aimed at high school physics students and is the…

  13. Tumor hypoxia: a new PET imaging biomarker in clinical oncology.

    PubMed

    Tamaki, Nagara; Hirata, Kenji

    2016-08-01

    Tumor hypoxia is associated with tumor progression and resistance to various treatments. Noninvasive imaging using positron emission tomography (PET) and F-18-labeled fluoromisonidazole (FMISO) was recently introduced in order to define and quantify tumor hypoxia. The FMISO uptake was closely correlated with pimonidazole immunohistochemistry and hypoxia-inducible factor 1 expression in basic studies. Tumor hypoxia in head and neck cancers and other tumors in a clinical setting may also indicate resistance to radiation and/or chemotherapy. Hypoxic imaging may thus play a new and important role for suitable radiation planning, including dose escalation and dose reduction based on the image findings. Such radiation-dose painting based on the findings of hypoxia may require high-performance PET imaging to provide high target-to-background ratio images and an optimal quantitative parameter to define the hypoxic region. A multicenter prospective study using data from a large number of patients is also warranted to test the clinical value of hypoxic imaging. PMID:26577447

  14. Apelin/APJ signaling in hypoxia-related diseases.

    PubMed

    He, Lu; Xu, Jin; Chen, Linxi; Li, Lanfang

    2015-12-01

    The regulatory peptide apelin is the endogenous ligand for the orphan G protein-coupled receptor APJ. Apelin and APJ exist in a variety of tissues, with special status in the heart, lung and tumors. Consequently, the apelin/APJ system exerts a broad range of activities that affect multiple organ systems. Accumulating evidence indicates that the expressions of apelin and APJ are significantly augmented by hypoxia through the hypoxia-inducible factor-1 alpha (HIF-1α) signaling pathway. Increased apelin promotes cellular proliferation, migration and survival, therefore regulating angiogenesis. In addition, the pre-administration of exogenous apelin is involved in the occurrence and development of hypoxia-induced pathological diseases. The purpose of this article is to review the properties of the apelin/APJ system, which is affected by hypoxic conditions, and the regulation of apelin/APJ signaling in hypoxia-associated disorders. Thus, the apelin/APJ system may be a potential therapeutic target in hypoxia-related diseases. PMID:26436483

  15. Modelling macrofaunal biomass in relation to hypoxia and nutrient loading

    NASA Astrophysics Data System (ADS)

    Timmermann, Karen; Norkko, Joanna; Janas, Urszula; Norkko, Alf; Gustafsson, Bo G.; Bonsdorff, Erik

    2012-12-01

    Nutrient loading of aquatic ecosystems results in more food for benthic macrofaunal communities but also increases the risk of hypoxia, resulting in a reduction or complete loss of benthic biomass. This study investigates the interaction between eutrophication, hypoxia and benthic biomass with emphasis on the balance between gains and loss of benthic biomass due to changes in nutrient loadings. A physiological fauna model with 5 functional groups was linked to a 3D coupled hydrodynamic-ecological Baltic Sea model. Model results revealed that benthic biomass increased between 0 and 700% after re-oxygenating bottom waters. Nutrient reduction scenarios indicated improved oxygen concentrations in bottom waters and decreased sedimentation of organic matter up to 40% after a nutrient load reduction following the Baltic Sea Action Plan. The lower food supply to benthos reduced the macrofaunal biomass up to 35% especially in areas not currently affected by hypoxia, whereas benthic biomass increased up to 200% in areas affected by eutrophication-induced hypoxia. The expected changes in benthic biomass resulting from nutrient load reductions and subsequent reduced hypoxia may not only increase the food supply for benthivorous fish, but also significantly affect the biogeochemical functioning of the ecosystem.

  16. Heart disease link to fetal hypoxia and oxidative stress.

    PubMed

    Giussani, Dino A; Niu, Youguo; Herrera, Emilio A; Richter, Hans G; Camm, Emily J; Thakor, Avnesh S; Kane, Andrew D; Hansell, Jeremy A; Brain, Kirsty L; Skeffington, Katie L; Itani, Nozomi; Wooding, F B Peter; Cross, Christine M; Allison, Beth J

    2014-01-01

    The quality of the intrauterine environment interacts with our genetic makeup to shape the risk of developing disease in later life. Fetal chronic hypoxia is a common complication of pregnancy. This chapter reviews how fetal chronic hypoxia programmes cardiac and endothelial dysfunction in the offspring in adult life and discusses the mechanisms via which this may occur. Using an integrative approach in large and small animal models at the in vivo, isolated organ, cellular and molecular levels, our programmes of work have raised the hypothesis that oxidative stress in the fetal heart and vasculature underlies the mechanism via which prenatal hypoxia programmes cardiovascular dysfunction in later life. Developmental hypoxia independent of changes in maternal nutrition promotes fetal growth restriction and induces changes in the cardiovascular, metabolic and endocrine systems of the adult offspring, which are normally associated with disease states during ageing. Treatment with antioxidants of animal pregnancies complicated with reduced oxygen delivery to the fetus prevents the alterations in fetal growth, and the cardiovascular, metabolic and endocrine dysfunction in the fetal and adult offspring. The work reviewed offers both insight into mechanisms and possible therapeutic targets for clinical intervention against the early origin of cardiometabolic disease in pregnancy complicated by fetal chronic hypoxia. PMID:25015802

  17. Metabolic adaptation to chronic hypoxia in cardiac mitochondria.

    PubMed

    Heather, Lisa C; Cole, Mark A; Tan, Jun-Jie; Ambrose, Lucy J A; Pope, Simon; Abd-Jamil, Amira H; Carter, Emma E; Dodd, Michael S; Yeoh, Kar Kheng; Schofield, Christopher J; Clarke, Kieran

    2012-05-01

    Chronic hypoxia decreases cardiomyocyte respiration, yet the mitochondrial mechanisms remain largely unknown. We investigated the mitochondrial metabolic pathways and enzymes that were decreased following in vivo hypoxia, and questioned whether hypoxic adaptation was protective for the mitochondria. Wistar rats were housed in hypoxia (7 days acclimatisation and 14 days at 11% oxygen), while control rats were housed in normoxia. Chronic exposure to physiological hypoxia increased haematocrit and cardiac vascular endothelial growth factor, in the absence of weight loss and changes in cardiac mass. In both subsarcolemmal (SSM) and interfibrillar (IFM) mitochondria isolated from hypoxic hearts, state 3 respiration rates with fatty acid were decreased by 17-18%, and with pyruvate were decreased by 29-15%, respectively. State 3 respiration rates with electron transport chain (ETC) substrates were decreased only in hypoxic SSM, not in hypoxic IFM. SSM from hypoxic hearts had decreased activities of ETC complexes I, II and IV, which were associated with decreased reactive oxygen species generation and protection against mitochondrial permeability transition pore (MPTP) opening. In contrast, IFM from hypoxic hearts had decreased activity of the Krebs cycle enzyme, aconitase, which did not modify ROS production or MPTP opening. In conclusion, cardiac mitochondrial respiration was decreased following chronic hypoxia, associated with downregulation of different pathways in the two mitochondrial populations, determined by their subcellular location. Hypoxic adaptation was not deleterious for the mitochondria, in fact, SSM acquired increased protection against oxidative damage under the oxygen-limited conditions. PMID:22538979

  18. Vitamin C supplementation does not improve hypoxia-induced erythropoiesis.

    PubMed

    Martinez-Bello, Vladimir E; Sanchis-Gomar, Fabian; Martinez-Bello, Daniel; Olaso-Gonzalez, Gloria; Gomez-Cabrera, Mari Carmen; Viña, Jose

    2012-12-01

    Hypoxia induces reactive oxygen species production. Supplements with antioxidant mixtures can compensate for the decline in red cell membrane stability following intermittent hypobaric hypoxia by decreasing protein and lipid oxidation. We aimed to determine whether supplementation with vitamin C is implicated in the regulation of erythropoiesis and in the oxygen-carrying capacity of the blood, and also whether antioxidant supplementation prevents the oxidative stress associated to intermittent hypoxia. Twenty-four male Wistar rats were randomly divided into four experimental groups: normoxia control (n=6), normoxia + vitamin C (n=6), hypoxia control (12 h pO(2) 12%/12 h pO(2) 21%) (n=6), and hypoxia + vitamin C (n=6). Animals were supplemented with vitamin C at a dose of 250 mg·kg(-1)·day(-1) for 21 days. Red blood cell count, hemoglobin, hematocrit, reticulocytes, erythropoietin, and oxidative stress parameters such as malondialdehyde and protein oxidation in plasma were analyzed at two different time points: basal sample (day zero) and final sample (day 21). Similar RBC, Hb, Hct, and Epo increments were observed in both hypoxic groups regardless of the vitamin C supplementation. There was no change on MDA levels after intermittent hypoxic exposure in any experimental group. However, we found an increase in plasma protein oxidation in both hypoxic groups. Vitamin C does not affect erythropoiesis and protein oxidation in rats submitted to intermittent hypoxic exposure. PMID:23270444

  19. Circulating factors are involved in hypoxia-induced hepcidin suppression.

    PubMed

    Ravasi, Giulia; Pelucchi, Sara; Greni, Federico; Mariani, Raffaella; Giuliano, Andrea; Parati, Gianfranco; Silvestri, Laura; Piperno, Alberto

    2014-12-01

    Hepcidin transcription is strongly down-regulated under hypoxic conditions, however whether hypoxia inhibits hepcidin directly or indirectly is still unknown. We investigated the time course of hypoxia-mediated hepcidin down-regulation in vivo in healthy volunteers exposed to hypobaric hypoxia at high altitude and, based on the hypothesis that circulating factors are implicated in hepcidin inhibition, we analyzed the effect of sera of these volunteers exposed to normoxia and hypoxia on hepcidin expression in Huh-7 cell lines. Hypoxia led to a significant hepcidin down-regulation in vivo that was almost complete within 72h of exposure and followed erythropoietin induction. This delay in hepcidin down-regulation suggests the existence of soluble factor/s regulating hepcidin production. We then stimulated HuH-7 cells with normoxic and hypoxic sera to analyze the effects of sera on hepcidin regulation. Hypoxic sera had a significant inhibitory effect on hepcidin promoter activity assessed by a luciferase assay, although the amount of such decrease was not as relevant as that observed in vivo. Cellular mRNA analysis showed that a number of volunteers' sera inhibited hepcidin expression, concurrently with ID1 inhibition, suggesting that inhibitory factor(s) may act through the SMAD-pathway. PMID:25065484

  20. Could mild hypoxia impair pilot decision making in emergencies?

    PubMed

    Legg, Stephen; Hill, Stephen; Mundel, Toby; Gilbey, Andrew; Schlader, Zac; Raman, Aaron

    2012-01-01

    The decreased pressure in the cabin of a pressurised aircraft (typically equivalent to ~8000 ft) reduces the oxygen level so that the blood oxygen saturation of all occupants falls from >97% (normoxia) at sea-level to below 92% (mild hypoxia). Although exposure to mild hypoxia does not affect well-learned cognitive and motor performance of aircrew, it has been proposed that it can affect the performance of some complex cognitive performance tasks involving multiple demands typical of emergency tasks that may have to be performed by pilots. In order to simulate some of these complex cognitive demands, 25 student volunteers participated in an experiment which assessed performance of complex logical reasoning and and multiple memory tasks before and after 2 hours of exposure to normoxia and mild hypoxia. Performance for the more difficult components of the complex reasoning task, especially involving conflict decisions, were marginally significantly degraded by mild hypoxia. Since the effects were only marginally significant future studies should investigate the effects of mild hypoxia on more subtle complex decision-making tasks. PMID:22316722

  1. Intermittent hypoxia induces functional recovery following cervical spinal injury

    PubMed Central

    Vinit, Stéphane; Lovett-Barr, Mary Rachael; Mitchell, Gordon S.

    2009-01-01

    Respiratory-related complications are the leading cause of death in spinal cord injury (SCI) patients. Few effective SCI treatments are available after therapeutic interventions are performed in the period shortly after injury (e.g. spine stabilization and prevention of further spinal damage). In this review we explore the capacity to harness endogenous spinal plasticity induced by intermittent hypoxia to optimize function of surviving (spared) neural pathways associated with breathing. Two primary questions are addressed: 1) does intermittent hypoxia induce plasticity in spinal synaptic pathways to respiratory motor neurons following experimental SCI? and 2) can this plasticity improve respiratory function? In normal rats, intermittent hypoxia induces serotonin-dependent plasticity in spinal pathways to respiratory motor neurons. Early experiments suggest that intermittent hypoxia also enhances respiratory motor output in experimental models of cervical SCI, (cervical hemisection) and that the capacity to induce functional recovery is greater with longer durations post-injury. Available evidence suggests that intermittent hypoxia-induced spinal plasticity has considerable therapeutic potential to treat respiratory insufficiency following chronic cervical spinal injury. PMID:19651247

  2. Neuroprotective effects of PKC inhibition against chemical hypoxia.

    PubMed

    Pavlaković, G; Eyer, C L; Isom, G E

    1995-04-01

    The effect of potassium cyanide-induced chemical hypoxia on protein kinase C (PKC) translocation and cell injury was studied in differentiated PC12 cells. The cellular distribution of PKC in control cells and cells exposed to 100 microM and 1 mM KCN for 30 min. was visualized by use of an anti-PKC antibody and confocal laser scanning microscope. In control differentiated PC12 cells, PKC was localized perinuclearly, while following 12-phorbol 13-myristate acetate (PMA) or KCN it was translocated to the plasma and organelle membranes. Western blot analysis was used to quantify the translocation. Chemical hypoxia increased the membrane-bound PKC to 210% of control levels, while chelerythrine, a PKC inhibitor, and block of calcium influx into the cells (with calcium channel blocker and calcium-free medium) prevented this effect. Cyanide-induced PKC translocation persisted for at least 120 min. Cell injury was monitored by measuring lactate dehydrogenase (LDH) efflux from the cells 24 hr after addition of cyanide. PKC activation plays a role in hypoxic damage, since PKC down-regulation (by overnight exposure to PMA) or inhibition (with chelerythrine or staurosporine) conferred protection against KCN-induced cytotoxicity. Ca2+ channel blocker nifedipine also protected against chemical hypoxia. None of the pretreatments rendered complete protection against cyanide-induced hypoxia, indicating that PKC-independent mechanism(s) are also activated during chemical hypoxia and contribute to cell injury. PMID:7796171

  3. The acquired radioresistance in HeLa cells under conditions mimicking hypoxia was attenuated by a decreased expression of HIF subunit genes induced by RNA interference

    SciTech Connect

    Doi, Nobutaka; Ogawa, Ryohei; Cui, Zheng-Guo; Morii, Akihiro; Watanabe, Akihiko; Kanayama, Shinji; Yoneda, Yuko; Kondo, Takashi

    2015-05-01

    The cancer cells residing in the hypoxic layer are resistant to radiation and these are ones responsible for cancer recurrence after radiation therapy. One of the reasons why hypoxic cancer cells acquire radioresistance may be attributable to changes in the gene expression profile by the activation of hypoxia inducible factors (HIFs). However, the details underlying this process remain unknown. In this study, we investigated the effects of knockdown of HIF subunit genes to elucidate how HIF subunit genes may be involved in the radioresistance acquired by HeLa cells following exposure to a hypoxia mimic. Interestingly, HIF-1α and HIF-2α seemed mutually complementary for each other when either of them was suppressed. We thus suppressed the expression of both genes simultaneously. To do this, we developed a short hairpin RNA (shRNA) targeting a high homology region between HIF-1α and HIF-2α. It was shown that the expression of the shRNA effectively suppressed the acquisition of radioresistance following the hypoxia mimic. Moreover, it was confirmed that suppression of both subunits resulted in the downregulation of stem cell markers and the suppression of spheroid formation during the hypoxia mimicking-conditions. This shRNA-mediated knockdown method targeting a common region shared by a family of genes may offer a new candidate cancer treatment. - Highlights: • Incubation with CoCl{sub 2} confers radioresistance to HeLa cells. • Both HIF-1α and HIF-2α are involved in the acquisition of radioresistance. • An shRNA to a homology region of HIF-1α and HIF-2α suppressed the radioresistance. • The shRNA decreased cells with stem cell markers and a stem cell phenotype.

  4. Hypoxia targeted carbon nanotubes as a sensitive contrast agent for photoacoustic imaging of tumors

    NASA Astrophysics Data System (ADS)

    Zanganeh, Saeid; Aguirre, Andres; Biswal, Nrusingh C.; Pavlik, Christopher; Smith, Michael B.; Alqasemi, Umar; Li, Hai; Zhu, Quing

    2011-03-01

    Development of new and efficient contrast agents is of fundamental importance to improve detection sensitivity of smaller lesions. Within the family of nanomaterials, carbon nanotubes (CNT) not only have emerged as a new alternative and efficient transporter and translocater of therapeutic molecules but also as a photoacoustic molecular imaging agent owing to its strong optical absorption in the near-infrared region. Drugs, Antibodies and nucleic acids could functionalize the CNT and prepare an appropriate system for delivering the cargos to cells and organs. In this work, we present a novel photoacoustic contrast agent which is based on a unique hypoxic marker in the near infrared region, 2-nitroimidazole -bis carboxylic acid derivative of Indocyanine Green conjugated to single walled carbon nanotube (SWCNT-2nitroimidazole-ICG). The 2-nitroimidazole-ICG has an absorption peak at 755 nm and an extinction coefficient of 20,5222 M-1cm-1. The conjugation of this marker with SWCNT shows more than 25 times enhancement of optical absorption of carbon nanotubes in the near infrared region. This new conjugate has been optically evaluated and shows promising results for high contrast photoacoustic imaging of deeply located tumors. The conjugate specifically targets tumor hypoxia, an important indicator of tumor metabolism and tumor therapeutic response. The detection sensitivity of the new contrast agent has been evaluated in-vitro cell lines and with in-vivo tumors in mice.

  5. Design and conduct of Caudwell Xtreme Everest: an observational cohort study of variation in human adaptation to progressive environmental hypoxia

    PubMed Central

    2010-01-01

    Background The physiological responses to hypoxaemia and cellular hypoxia are poorly understood, and inter-individual differences in performance at altitude and outcome in critical illness remain unexplained. We propose a model for exploring adaptation to hypoxia in the critically ill: the study of healthy humans, progressively exposed to environmental hypobaric hypoxia (EHH). The aim of this study was to describe the spectrum of adaptive responses in humans exposed to graded EHH and identify factors (physiological and genetic) associated with inter-individual variation in these responses. Methods Design Observational cohort study of progressive incremental exposure to EHH. Setting University human physiology laboratory in London, UK (75 m) and 7 field laboratories in Nepal at 1300 m, 3500 m, 4250 m, 5300 m, 6400 m, 7950 m and 8400 m. Participants 198 healthy volunteers and 24 investigators trekking to Everest Base Camp (EBC) (5300 m). A subgroup of 14 investigators studied at altitudes up to 8400 m on Everest. Main outcome measures Exercise capacity, exercise efficiency and economy, brain and muscle Near Infrared Spectroscopy, plasma biomarkers (including markers of inflammation), allele frequencies of known or suspected hypoxia responsive genes, spirometry, neurocognitive testing, retinal imaging, pupilometry. In nested subgroups: microcirculatory imaging, muscle biopsies with proteomic and transcriptomic tissue analysis, continuous cardiac output measurement, arterial blood gas measurement, trans-cranial Doppler, gastrointestinal tonometry, thromboelastography and ocular saccadometry. Results Of 198 healthy volunteers leaving Kathmandu, 190 reached EBC (5300 m). All 24 investigators reached EBC. The completion rate for planned testing was more than 99% in the investigator group and more than 95% in the trekkers. Unique measurements were safely performed at extreme altitude, including the highest (altitude) field measurements of exercise capacity, cerebral blood

  6. Dendritic cells phenotype fitting under hypoxia or lipopolysaccharide; adenosine 5'-triphosphate-binding cassette transporters far beyond an efflux pump.

    PubMed

    Lloberas, N; Rama, I; Llaudó, I; Torras, J; Cerezo, G; Cassis, L; Franquesa, M; Merino, A; Benitez-Ribas, D; Cruzado, J M; Herrero-Fresneda, I; Bestard, O; Grinyó, J M

    2013-06-01

    This study examines adenosine 5'-triphosphate-binding cassette (ABC) transporters as a potential therapeutic target in dendritic cell (DC) modulation under hypoxia and lipopolysaccharide (LPS). Functional capacity of dendritic cells (DCs) (mixed lymphocyte reaction: MLR) and maturation of iDCs were evaluated in the presence or absence of specific ABC-transporter inhibitors. Monocyte-derived DCs were cultured in the presence of interleukin (IL)-4/granulocyte-macrophage colony-stimulating factor (GM-CSF). Their maturation under hypoxia or LPS conditions was evaluated by assessing the expression of maturation phenotypes using flow cytometry. The effect of ABC transporters on DC maturation was determined using specific inhibitors for multi-drug resistance (MDR1) and multi-drug resistance proteins (MRPs). Depending on their maturation status to elicit T cell alloresponses, the functional capacity of DCs was studied by MLR. Mature DCs showed higher P-glycoprotein (Pgp) expression with confocal microscopy. Up-regulation of maturation markers was observed in