Hypoxically inducible barley alanine aminotransferase: cDNA cloning and expression analysis

A 1.75 kb cDNA containing the entire coding sequence of the hypoxically inducible alanine aminotransferase (AlaAT) from barley roots was isolated and sequenced. This clone has an open reading frame of 1446 bp, and a deduced amino acid sequence of 482 residues, giving an estimated protein molecular mass of 52 885 Da. RNA blot analysis of barley root tissue showed a 4-fold increase of a single AlaAT-2 mRNA band after 12–24 hours of hypoxic stress, followed by a decrease in message levels after 48 h of hypoxic conditions. AlaAT-2 protein concentration increased in a similar pattern to AlaAT activity in root tissue, to almost 6-fold the aerobic level after 96 h of hypoxic stress. AlaAT-2 activity increased more than 2-fold in roots of Panicum miliaceum exposed to hypoxia, and is the same isoform as the light inducible AlaAT in P. miliaceum leaves. The unique expression patterns of AlaAT-2 in root and leaf tissue upon exposure to different environmental stimuli is also discussed.     

Oxygen uptake during swimming in a hypobaric hypoxic environment

The purpose of this study was to determine oxygen uptake (VO2) at various water flow rates and maximal oxygen uptake (VO2max) during swimming in a hypobaric hypoxic environment. Seven trained swimmers swam in normal [N; 751 mmHg (100.1 kPa)] and hypobaric hypoxic [H; 601 mmHg (80.27 kPa)] environments in a chamber where atmospheric pressure could be regulated. Water flow rate started at 0.80 m.s-1 and was increased by 0.05 m.s-1 every 2 min up to 1.00 m.s-1 and then by 0.05 m.s-1 every minute until exhaustion. At submaximal water flow rates, carbon dioxide production (VCO2), pulmonary ventilation (VE) and tidal volume (VT) were significantly greater in H than in N. There were no significant differences in the response of submaximal VO2, heart rate (fc) or respiratory frequency (fR) between N and H. Maximal VE, fR, VT, fc, blood lactate concentration and water flow rate were not significantly different between N and H. However, VO2max under H [3.65 (SD 0.11) l.min-1] was significantly lower by 12.0% (SD 3.4)% than that in N [4.15 (SD 0.18) l.min-1]. This decrease agrees well with previous investigations that have studied centrally limited exercise, such as running and cycling, under similar levels of hypoxia.     

IL-1β promotes hypoxic vascular endothelial cell proliferation through the miR-24-3p/NKAP/NF-κB axis

Purpose: Our previous data indicated that miR-24-3p is involved in the regulation of vascular endothelial cell (EC) proliferation and migration/invasion. However, whether IL-1β affects hypoxic HUVECs by miR-24-3p is still unclear. Therefore, the present study aimed to investigate the role and underlying mechanism of interleukin 1β (IL-1β) in hypoxic HUVECs.Methods: We assessed the mRNA expression levels of miR-24-3p, hypoxia-inducible factor-1α (HIF1A) and NF-κB-activating protein (NKAP) by quantitative real-time polymerase chain reaction (RT-qPCR). ELISA measured the expression level of IL-1β. Cell counting kit-8 (CCK-8) assays evaluated the effect of miR-24-3p or si-NKAP+miR-24 on cell proliferation (with or without IL-1β). Transwell migration and invasion assays were used to examine the effects of miR-24-3p or si-NKAP+miR-24-3p on cell migration and invasion (with or without IL-1β). Luciferase reporter assays were used to identify the target of miR-24-3p.Results: We demonstrated that in acute myocardial infarction (AMI) patient blood samples, the expression of miR-24-3p is down-regulated, the expression of IL-1β or NKAP is up-regulated, and IL-1β or NKAP is negatively correlated with miR-24-3p. Furthermore, IL-1β promotes hypoxic HUVECs proliferation by down-regulating miR-24-3p. In addition, IL-1β also significantly promotes the migration and invasion of hypoxic HUVECs; overexpression of miR-24-3p can partially rescue hypoxic HUVECs migration and invasion. Furthermore, we discovered that NKAP is a novel target of miR-24-3p in hypoxic HUVECs. Moreover, both the overexpression of miR-24-3p and the suppression of NKAP can inhibit the NF-κB/pro-IL-1β signaling pathway. However, IL-1β mediates suppression of miR-24-3p activity, leading to activation of the NKAP/NF-κB pathway. In conclusion, our results reveal a new function of IL-1β in suppressing miR-24-3p up-regulation of the NKAP/NF-κB pathway.     

Discovery of 2,4-thiazolidinedione-tethered coumarins as novel selective inhibitors for carbonic anhydrase IX and XII isoforms

Different 2,4-thiazolidinedione-tethered coumarins 5a–b, 10a–n and 11a–d were synthesised and evaluated for their inhibitory action against the cancer-associated hCAs IX and XII, as well as the physiologically dominant hCAs I and II to explore their selectivity. Un-substituted phenyl-bearing coumarins 10a, 10 h, and 2-thienyl/furyl-bearing coumarins 11a–c exhibited the best hCA IX (K_Is between 0.48 and 0.93 µM) and hCA XII (K_Is between 0.44 and 1.1 µM) inhibitory actions. Interestingly, none of the coumarins had any inhibitory effect on the off-target hCA I and II isoforms. The sub-micromolar compounds from the biochemical assay, coumarins 10a, 10 h and 11a–c, were assessed in an in vitro antiproliferative assay, and then the most potent antiproliferative agent 11a was tested to explore its impact on the cell cycle phases and apoptosis in MCF-7 breast cancer cells to provide more insights into the anticancer activity of these compounds.     

Hypoxia and its effect on the cellular system

Eukaryotic cells utilize oxygen for different functions of cell organelles owing to cellular survival. A balanced oxygen homeostasis is an essential requirement to maintain the regulation of normal cellular systems. Any changes in the oxygen level are stressful and can alter the expression of different homeostasis regulatory genes and proteins. Lack of oxygen or hypoxia results in oxidative stress and formation of hypoxia inducible factors (HIF) and reactive oxygen species (ROS). Substantial cellular damages due to hypoxia have been reported to play a major role in various pathological conditions. There are different studies which demonstrated that the functions of cellular system are disrupted by hypoxia. Currently, study on cellular effects following hypoxia is an important field of research as it not only helps to decipher different signaling pathway modulation, but also helps to explore novel therapeutic strategies. On the basis of the beneficial effect of hypoxia preconditioning of cellular organelles, many therapeutic investigations are ongoing as a promising disease management strategy in near future. Hence, the present review discusses about the effects of hypoxia on different cellular organelles, mechanisms and their involvement in the progression of different diseases.     

Intracellular Signals Coupled to Muscarinic Acetylcholine Receptor Activation in Cerebral Frontal Cortex from Hypoxic Mice

1. The aim of the present work was to determine hypoxia-induced modifications in the cascade of intracellular events coupled to muscarinic acetylcholine receptor (mAChR) activation in brain. For this purpose, enzymatic activities were measured on normoxically incubated frontal cortical slices from mice exposed to hypobaric hypoxia for 72 hr.2. We found that hypoxia induced alterations in several cerebral enzymatic basal activities: it increased nitric oxide synthase (NOS), but it decreased both membrane protein kinase C (PKC) and phospholipase C activities.3. The mAChR agonist carbachol was found to increase phosphoinositide hydrolysis to greater values in hypoxic tissues than those found in normoxic conditions. Furthermore, a greater translocation of PKC in response to carbachol was observed in hypoxic tissues than in normoxic ones.4. Besides, carbachol induced a drastic reduction of NOS activity in hypoxic brains, at concentrations that stimulated this enzyme activity in normoxic preparations. In the latter, inhibition is obtained only with high concentrations of the cholinergic muscarinicagonist.5. These results pointed to a carbachol-mediated mAChR hyperactivity induced by hypoxic insult.6. The possibility that these effects would account for a compensatory mechanism to diminish NOS hyperactivity, probably protecting for NO neurotoxic action in hypoxic brain, is also discussed.     

缺氧习服对冻伤大鼠骨骼肌耗氧量的影响

目的与方法使用生物组织氧耗测量系统测定了常氧冻伤(FN)、急性缺氧冻伤(FAH)和缺氧习服缺氧冻伤(FHAC)大鼠后肢重度冻伤前后腓肠肌耗氧量的变化,以探讨缺氧习服加重冻伤组织损伤的机理.结果冻前,FHAC组腓肠肌耗氧量降低26.2%.冻后1d,FN、FAH和FHAC组腓肠肌耗氧量为5.93±0.66,4.74±1.87和0.76±0.39[kPa/(g*min)],分别较各自冻前水平降低76.3%,77.9%和95.9%,FHAC组明显低于其余两组;冻后5d三组的耗氧量分别恢复至各自冻前水平的62.8%、44.9%和28.8%,FHAC组仍明显低于其余两组,提示缺氧习服冻伤后骨骼肌代谢率降低更明显,恢复更缓慢.结论缺氧习服和冻伤均使腓肠肌耗氧量明显减少,二者的叠加使缺氧习服大鼠冻后腓肠肌耗氧量进一步降低,表明组织代谢的变化是影响冻伤组织损伤及修复的主要因素之一.     

急性低氧和间断低氧习服对大鼠主动脉收缩和舒张功能的影响

目的：观察急性低和间断低氧习服对大鼠主动脉收缩和舒张功能的影响。方法：用去甲肾上腺素（ＮＥ）诱发大鼠离体动脉环的收缩,反映收缩功能的变化,主动脉环以０．６２μｍｏｌ／Ｌ ＮＥ预收缩后用乙酰胆碱（Ａｃｈ）舒张对抗,反映舒张功能的变化。结果：与常氧对照组相比,急性低氧和间断低氧习照大鼠主动脉对去甲肾上腺素（ＮＥ１０＾－９,１０＾０８,１０＾－７ｍｏｌ／Ｌ）介导的收缩反应显著增强（Ｐ〈０．０５～０．０１     

Cytoplasmic potassium-sodium balance in the cardiac muscle cell of young and old rats in oxygen-substrate deficiency

Age-related changes in the concentrations of the main cations potassium and sodium in the cardiac muscle cell of Wistar rats were studied. The cytoplasmic concentrations of potassium and sodium were measured by electron probe microanalysis. The results obtained showed differences both in concentrations of the cations between young and old reference animals, and in the cardiomyocyte response to the state of acute hypoxic deenergization modeled on a perfused heart. The data obtained are consistent with the hypothesis of the presence of genetically determined age-related changes in the conductance of potassium channels, which occur in old animals against the background of short supply of oxygen and substrate to tissues.