Rapamycin Protects Cardiomyocytes against Anoxia/Reoxygenation Injury by Inducing Autophagy through the PI3k/Akt Pathway

The purpose of this study was to investigate the potential cardioprotection roles of Rapamycin in anoxia/reoxygenation（A/R） injury of cardiomyocytes through inducing autophagy, and the involvement of PI3k/Akt pathway. We employed simulated A/R of neonatal rat ventricular myocytes（NRVM） as an in vitro model of ischemial/reperfusion（I/R） injury to the heart. NRVM were pretreated with four different concentrations of Rapamycin（20, 50, 100, 150 μmol/L）, and pretreated with 10 mmol/L 3-methyladenine（3MA） for inhibiting autophagy during A/R. Then, Western blot analysis was used to examine variation in the expression of LC3-Ⅱ, LC3-Ⅰ, Bim, caspase-3, p-PI3KⅠ, PI3KⅠ, p-Akt and Akt. In our model, Rapamycin had a preferential action on autophagy, increasing the expression of LC3-Ⅱ/ LC3-Ⅰ, whereas decreasing the expression of Bim and caspase-3. Moreover, our results also demonstrated that Rapamycin inhibited the activation of p-PI3KⅠ and enhanced the activation of p-Akt. It is concluded that Rapamycin has a cardioprotection effect by inducing autophagy in a concentration-dependent manner against apopotosis through PI3K/Akt signaling pathway during A/R in NRVM.

The antiapoptotic effect of insulin against anoxia/reoxygenation injury in cultured cardiomyocyte of neonatal rat

Objective： To study protective effect of insulin against cardiomyocyte apoptosis in anoxia/reoxygenation （A/R） injury of neonatal rat. Methods： The model of A/R injury was finished through receiving anoxia for 2h and reoxygenation for 4h in cultured cardiomyocytes of neonatal rat. The cardiomyocytes were divided randomly into 3 groups： control group （CON）, anoxia/reoxygenation group （A/R） and insulin-treated group （INS）. At the end of reoxygenation of 4 hours, activities of lactate dehydrogenase （LDH）, contents of malondiaidehyde （MDA）, were assessed through spectrophotometric procedures, myocyte apoptosis were detected through TUNEL and DNA Ladder. Results： MDA, LDH, and Apoptosis Index were significantly decreased in INS group compared with A/R group （P〈0.01）. Conclusion： Insulin has a protective effect against A/R injury in cultured cardiomyocyte of neonatal rat; the protective mechanism may contribute to antiapoptosis of insulin.

Ecological Devastation in Lake Victoria: Part A: Thermal Structure and Anoxia

Lake Victoria is the second (excl. Caspian Sea) largest lake in the world by surface area and 7th by Volume. The lake and catchment territories are shared between three countries, Kenya, Uganda and Tanzania. A research was carried out during 1990-1992 exploring the changes of the thermo-chemical structure occurred after the invasion of Nile Perch. Results of changes of physico-chemical (Temperature, DO and pH) conditions are summarized in this paper. The anoxic conditions by space and time were enhanced. Enhancement of pollutant supply from anthropogenic developments of terrestrial sources and atmospheric dust deposition accompanied by the deleterious effects of the Nile Perch invasion caused enhancement of anoxia in the lake in space and time. The combination of bottom-up nutrient supply and strong mixing conditions, expressed as low RTR values accelerate phytoplankton growth rate and production. The surplus of organic matter originated from algal biomass, enhanced anoxia.

Comparative insights into mitochondrial adaptations to anoxia in brain

Numerous diseases and pathologies impair the delivery of oxygen to brain, with rapid and deleterious consequences. For example, diseases related to systemic hypoxemia （e.g., chronic pulmonary disorders, cystic fibrosis）, decreased oxygen carrying capacity of blood （e.g., anemia）, or decreased transport （e.g., heart attack, stroke） can all reduce or entirely prevent the delivery of oxygen to brain cells, resulting in the initiation of programmed cell death pathways, necrosis, or excitotoxic cell death in brain （Pamenter, 2014）. However, oxygen-limited environments are common on earth and many organisms naturally experience periods of intermit- tent or prolonged hypoxia or anoxia in their daily and/or annual life cycles （Bickler and Buck, 2007）.

Epidemio-Clinical Characteristics of Perinatal Anoxia and Immediate Outcome of Patients at Hospital Teaching Gabriel Toure of Bamako

Introduction: Neonatal asphyxia (NA) is one of the most likely causes of neuro-developmental abnormalities in children. In Mali it is responsible for half of the early deaths and the third of neonatal mortality. Updated data would help understand and improve intervention strategies to reduce mortality. Objective: It is the study of epidemiological and clinical characteristics, the immediate outcome and the factors associated with newborn (NB) mortality with NA. Material and Methods: This was a prospective cross-sectional study from June 27th to September 3rd 2016 about the NBs admitted for NA in the Hospital Teaching Gabriel Touré of Bamako. The clinical and biological data including the prognosis were collected from the health records of women, the liaison sheets and the medical file. The analysis was done using the software Epi info version 3.5.1. Results: 76 NBs were included which represented 23.45% of hospitalizations. The majority (89.5%, n = 68) were admitted to less than 24 hours of life for NA grade III according to the Sarnat classification (43.4%, n = 33). The average age of mothers was 24.17 ± 5.5 years. Almost half (41.3%, n = 31) were primigravida. The most common obstetrical event was dystocia (64.5%, n = 49). The prognosis was poor in grade III anoxia in our patients (56%) of deaths. Conclusion: The périnatal anoxia (PA) is a major health issue in Mali because of its frequency and severity. Monitoring of pregnancies, delivery assisted by skillful and qualified personnel, mastery of neonatal resuscitation techniques are good means of prevention.

在GDNF基因修饰的骨髓基质细胞与缺氧复氧神经细胞的共培养中神经细胞凋亡的变化

目的:探讨胶质源性神经营养因子(GDNF)基因修饰的骨髓基质细胞(BMSCs)对缺氧复氧神经细胞的保护作用。方法:GDNF基因修饰的BMSCs(BMSCs/GDNF)经诱导后与缺氧复氧神经细胞共培养,采用Hoechst33258检测神经细胞凋亡在共培养细胞中的表达。结果:BMSCs/GDNF组的神经细胞凋亡率显著低于BMSCs组和缺氧组(P<0.05)。结论:BMSCs/GDNF通过抑制缺氧复氧神经细胞凋亡发挥神经保护作用。

慢性缺氧和氯化钴引起红细胞增多时血液流变学变化

本文研究目的是探讨红细胞增多和慢性缺氧对血液流变学和右心室肥大的影响。实验的大鼠分4组:(1)对照组;(2)单纯红细胞增多组:以CoCl_2注射引起大鼠RBC增多;(3)慢性缺氧组:在模拟4000m高度慢性减压47天;(4)慢性减压复合CoCl_2注射组。结果表明慢性缺氧或单纯RBC增多均引起所有切变率下尤其是低切变率下的血液粘滞性增加、右室收缩压增高和右室指数增大;缺氧复合RBC增多上述指标更进一步增加。右室指数与Ht及低切变率时(2.24sec^(-1))血液粘滞性呈明显正相关。以上结果证明RBC增多,在缺氧性右心肥大发生上起重要作用,此外还讨论了RBC增多引起右心肥大的机制。

Effects of hypoxia,hyperoxia on the regulation of expression and activity of matrix metalloproteinase-2 in hepatic stellate cells

AIM To study the effects of hypoxia, hyperoxia on the regulation of expression and activity of matrix metalloproteinase-2 (MMP-2) in hepatic stellate cells ( HSC).``METHODS The expressions of MMP-2, tissue inhibitor of mjatrix metalloproteinese-2 ( TIMP-2 ) and membrane type matrix metalloproteiness-l (MT1-MMP) in cultured rat HSC were detected by immunocytochemistry (ICC) and in situ hybridization (ISH). The contents of MMP-2 and TIMP-2 in culture supernatant were detected with ELISA and the activity of MMP-2 in supematant was revealed by zymography.``RESULTS In the situation of hypoxia for 12 h, the expression of MMP-2 protein wss enhenced (hypoxiagroup positive indexes: 5.7 ± 2.0, n = 10; control: 3.2 ±1 .0. n -- 7; P＜0.05). while TIMP-2 protein wss decreased in HSC ( hypoxia group positive indexes: 2.5 ± 0.7, n =10: control: 3.6 ± 1.0, n = 7; P＜O.05), and the activity ( total A) of MMP-2 in supematant declined obviously (hypoxia group: 7.334 ± 1.922, n = 9; control: 17.277 ±7.424. n= 11; P＜0.01). Compared the varied duration of hypoxia, the changes of expressions including mRNA and protein level as well as activity of MMP-2 were most notable in 6 h group. The highest value (Ahypoxia-Acontrol) ofthe protein and the most intense signal of mRNA were in the period of hypoxia for 6 h, along with the lowest activity of MMP-2. In the situation of hyperoxia for 12 h,the contonts (A450) of MMP-2 and TIMP-2 in supernatant were both higher then those in the control, especially the TIMP-2 (hyperoxia group: 0.0499 _+ 0.0144, n = 16;control: 0.0219 ± 0.0098, n = 14; P＜0.01), and so was the activity of MMP-2 (hyperoxia group: 5.252 _+ 0.771,n: 14; control: 4.304 +_ 1 .083, n = 12; P＜0.05), and the expression of MT1-MMP was increased.``CONCLUSION HSC Js sensitive to the oxygen, hypoxia enhances the expression of MMP-2 and the effect is more marked at the early stage; hyperoxia mainly raises the activity of MMP-2.

Meiofauna distributions at the oxygen minimum zone in Changjiang (Yangtze) River Estuary waters

A quantitative study on meiofauna was carried out along a transect throughout the Changjiang Estuary＇ s oxygen minimum zone （OMZ） in the East China Sea. There exist two distinct station groups in the OMZ： the fine-grained hypoxic area and the more fine-grained anoxie area. Meiofauna abundance ranged from （ 101.5±31.0） ind./cm^2 （ hypoxie area） to （369.9±123.9） ind./cm^2（ anoxic area） along the transect. Free-living marine nematodes were the numerically dominant meiofauna at every station. The anoxic area differed significantly in meiofauna abundance and vertical distribution pattern from the hypoxic area. Within the anoxic area, nematodes abundance increased and amounted to over 90% of the total meiofauna; about 50% of nematodes were found in the 2-5 and 5-8 cm layers. At hypoxie stations, about over 85 % were restricted to the top 2 cm. Benthic eopepod abundance and dominance decreased consistently with the oxygen gradient. The pattern of meiofauna biomass was similar to that of abundance. The correlation analysis of the meiofauna numbers and environmental parameters indicated that abundance and biomass of total meiofauna and nematodes had significant or highly significant （ P 〈 0.05 or P 〈 0.01 ） correlations with Chl a and Pha a, but no significant （ P 〉 0.05 ） correlations with bottom-water oxygen （ BWO2 ）. On the other hand, there was a highly significant positive correlation between benthic eopepod abundance and bottom-water oxygen （P 〈 0.05 ）. The investigation on the nematode community structure indicated that two different nematode communities existed in hypoxic and anoxic areas. In certain way, the shift in nematode species composition distinguishes the anoxia to hypoxia. Nematode diversity was generally lower within the anoxic stations than the hypoxic ones, but the difference was not significant. Indices of the nematode community structure varied in relation to the bottom-water oxygen together with bottom-water temperature, Chl a concentration and median grain size of sediment.

RhoA/ROCK pathway regulates hypoxia-induced myocardial cell apoptosis

Objective:To observe the regulatory effects of RhoA/ROCK pathway on the apoptosis of cardiac myocyte induced by anoxia and its mechanism.Methods:The model of cardiac myocyte anoxia was established.The beat pulsations and apoptosis rales after 1 h,3 h,6 h,9 h and 12 h of anoxia were recorded and the expressions of RhoA,ROCK1/2,p-PI3 K,p-AKT and caspae-3 were detected,too.The apoptosis and the expressions of related proteins were detected after RNAi of RhoA and the inhibition of ROCK by Y-27632.Results:The beat pulsations after 1 h,3 h,6 h.9h and 12 h decreased gradually but the apoptosis rates increased gradually,and the expressions of RhoA,ROCK1/2,p-P13 K,p-AKT and caspase-3 were increasing along with the increasing duration of anoxia.The apoptotic rales after 1 h,3 h,6 h.9 h and 12 h of anoxia were(4.36±0.98)%,(8.36±2.12)%,(15.32±3.62)%,(18.68±4.83)%and(24.56±6.22)%.respectively and decreased more significantly than control group in different time points of anoxia(P<0.05).and the expressions of RhoA,ROCK1/2,p-PI3 K,p-AKT and caspase-3 decreased significantly(P<0.05).The apoptosis rate and the expressions of RhoA,ROCK1/2,p-PI3 K,p-AKT and caspase-3 decreased significantly(P<0.05) after the inhibition of ROCK by Y-27632(P<0.05).Conclusions:RhoA/ROCK pathway plays a critical role in the regulation of the apoptosis of cardiac myocyte induced by anoxia,which may be accompanied by regulating the activity of PI3K/AKT/Caspase-3 pathway.

Attenuation of Nitric Oxide Synthase Gene Expression in Rat Lung Induced by Hypoxia

In order to investigate the role of nitric oxide(NO) in pathogenesis of hypoxic pulmonary hypertension(HPH), the mean pulmonary arterial pressure(mPAP), mRNA expression of NO synthase(NOS) in lung tissues, cGMP levels, and their relationships were studied in rats exposed to hypoxia from 8 h to 28days. The results showed that mPAP began to increase in animals exposed to 10 % O2 for 8 h. Moreover, the longer the exposure, the higher the mPAP.Northern blot analysis and dot blot hybridization indicated that mRNA expression of NO in lung tissues of hypoxic rats tended to decrease with exposure days, but that of β-actin which acted as a control did not alter. The cGMP levels of plasma and lung tissues in hypoxic rats also inclined to be lower with exposure days. A marked negative correlations between the changes of cGMP levels and those of mPAP were found. It was suggested that mRNA expression of NOS gene was attenuated in hypoxic lung tissues, which may be one of important pathogenetic mechanisms of HPH.

Environmental Redox Changes of the Ancient Sea in the Yangtze Area during the Ordo-Silurian Transition

Extensive organic-matter （OM） rich facies （black shales） occur in the Ordo-Silurian boundary successions in the Yangtze area, South China. To investigate the redox changes of the Yangtze Sea during the Ordo-Silurian transition, two OM sections （Wangjiawan in Yichang, Hubei Province, and Sanjiaguan in Zhangjiajie, Hunan Province） straddling the Ordo-Silurian boundary are studied. The measurements finished in this study include contents of the total organic carbon （TOC）, pyrite sulphur, and different species of Fe, including dithionite-extractable Fe （FED）, pyrite Fe （FeP）, HCl-extractable Fe （FeH）, and total Fe （FeT）, in black shales, as well as other redox proxies, such as the SIC ratio, the ratio between highly reactive Fe （FeHR = FeD ＋ FeP） and FeT, and the FeP/（FeP ＋ FeH） ratio, known as the degree of pyritization （DOP）. In the Wangjiawan section, the Middle Ashgill sediments have high FeHR/FeT ratios （0.20-0.77; avg. 0.45）, high DOP values （0.21-0.72; avg. 0.54）, and a relatively constant sulfur content independent of the organic carbon content. By the contrast, the mid-early Hirnantian deposits generally have low FeHR/FeT ratios （0.10-0.35; avg. 0.21）, low DOP values （0.11- 0.40; avg. 0.28）, and SIC values are clustering on the normal marine value （SIC = 0.36）. The late Hirnantian and early Rhuddanian deposits, similar to those of the Middle Ashgill deposits, are characterized by high FeHR/FeT ratios （0.32-0.49; avg. 0.41）, high DOP values （0.46-0.68; avg. 0.53） and fairly constant sulfur contents. These data suggest the occurrences of marine anoxia on the Yangtze Sea shelf during intervals of the Mid Ashgill, Late Hirnantian and Early Rhuddanian, and ventilated and oxygenated marine conditions during the mid-early Hirnantian time. The mid-early Hirnantian ventilated event was concomitant with the global glacial period, likely resulted from the glacio-eustatic sea-level fall and subsequent circulation of cold, dense oxygenated waters upon the shelf seabed. Accordingly, the abrupt change from oxygenated to anoxic marine waters from the late Hirnantian and the early Rhuddanian were resulted from the post-glacial rise of eustatic sea level. Combined with the data from Sanjiaguan section near the subemergent highland, salinity stratification of water columns are strongly evidenced by very low S/C ratios （ 0.00-0.08, avg. 0.02）, low FeHR/FeT ratios （0.10-0.37, avg. 0.27）, low DOP values （0.01-0.27, avg. 0.10）, and TOC contents （0.72%-4.27%, avg. 2.55%）. Under this circumstance, the anoxic water columns could have formed beneath the halocline, above which desalinized waters formed. In the Wangjiawan section, TOC contents are generally high （0.94- 9.32%, avg. 4.44%）, but low （0.35%-2.12%, avg. 1.29%） in the mid-early Hirnantian that is coincident with the oceanic oxic stage, together with relation of the organic contents to the stratal thickness, suggesting that the accumulation of the organic matter was mainly controlled by the oxygen levels of the water columns; on the other hand, productivity and depositional rate may also have played a role in the organic accumulation and preservation.

Effect of stellate block on vasomotor factor, vascular endothelial nitricoxide synthase and pulmonary arterial pressure in rabbits with hypoxic pulmonary artery hypertension

BACKGROUND： At present, inhalation of nitrogen monoxidum （NO） or other angiotenic is widely used to cure hypoxic pulmonary artery hypertension. In addition, recent researches demonstrate that postganglionic fiber of stellate ganglion can regulate contents of blood vessel endothelium-calcitonin gene-related peptide （BVE-CGRP） and nitricoxide synthase （NOS） in lung tissue. Therefore, stellate ganglion which is blocked with the local anesthetic may cause therapeutic effects on hypoxic pulmonary artery hypertension. OBJECTIVE： To observe the effects of stellate block on calcitonin gene-related peptide （CGRP） of vasodilation factors, prostacyclin, endothelin-i of vasoconstriction factors, thromboxan, blood vessel endothelium-nitricoxide synthase （BVE-NOS） and mean arterial pressure of lung tissue in rabbits with hypoxic pulmonary artery hypertension. DESIGN： Randomly controlled animal study. SETTING： Neurological Institute of Taihe Hospital Affiliated to Yunyang Medical College. MATERIALS： A total of 24 adult Japanese rabbits of both genders and weighing 2.3 - 2.6 kg were provided by Animal Experimental Center of Hubei Academy of Medical Science. SP kit was provided by Beijing Zhongshan Biotechnology Co., Ltd.; moreover, kits of endothelin-1, CGRP, prostacyclin and thromboxan were provided by Radioimmunity Institute, Scientific and Technological Developing Center, General Hospital of Chinese PLA, and color image analytical system （Leica-Q500IW） was made in Germany. METHODS：The experiment was carried out in the Neurological Institute of Taihe Hospital affiliated to Yunyang Medical College from February to December 2002. ① Rabbits were performed with aseptic manipulation to exposure left stellate ganglion and then it was put in epidural catheter for 1 week. In addition, one end of epidural catheter was fixed near by stellate ganglion and the other end was fixed through dorsal neck. All rabbits were randomly divided into 4 groups, including normal control group, stellate block group, hypoxia group and hypoxia ＋ stellate block group, with 6 in each group. Rabbits in the normal control group were perfused with saline through epidural catheter with 0.5 mL once for three times per day and 3 successive days in total; in addition, rabbits in the stellate block group were perfused with 2.5 g/L bupivacaine through epidural catheter with 0.5 mL once for three times per day and 3 successive days in total. Rabbits in the hypoxia group were used to establish hypoxic pulmonary artery hypertension models. That was to say, the experimental rabbits were put in hypoxic box （containing sodalime and calcium chloride to absorb CO2 and water） and given various flows of oxygen and nitrogen through the two lateral wells simultaneously. And then, oxygen was monitored with oxygen-concentration monitoring device to control the concentration in （10±2）% for 8 hours per day and 2 successive weeks in total. Rabbits in the hypoxia ＋ stellate block group were used to establish hypoxia models as the same as those in the hypoxia group. Two weeks later, 2.5 g,/L bupivacaine was pushed into epidural catheter with 0.5 mL once for three times per day and 3 successive days in total. Breast was directly opened to measure mean pulmonary artery pressure.② 6 mL blood was collected through pulmonary arterial duct to measure levels of plasma CGRP, prostacyclin, endothelin-I and thromboxane with radio-immunity technique; meanwhile, immunohistochemical staining was used to observe the changes of BVE-NOS content of the experimental rabbits in all groups. MAIN OUTCOME MEASURES： Changes of CGRP, prostacyclin, endothelin-1 and thromboxane and BVE-NOS. RESULTS： A total of 24 experimental rabbits were involved in the final analysis. ①As compared with those in the normal control group, hypoxic pulmonary artery hypertension of the experimental rabbits was higher in the hypoxia group and hypoxia ＋ stellate block group after hypoxia [（3.8±0.30）, （3.16±0.45）, （2.60± 0.27） kPa, P 〈 0.05, 0.01]; CGRP was lower [（68.20 ±8.78）, （108.24 ±14.35）, （130.25 ±22.70） ng/L, P 〈 0.05, 0.01]; prostacyclin was lower [（94.45± 10.68）, （98.77± 12.31）, （155.27±20.67） ng/L, P 〈 0.01]; endothelin-1 was higher [（184.7±29.66）, （115.27± 13.62）, （98.20±11.52）, ng/L, P 〈 0.05, 0.01]; thromboxan was higher [（226.27 ±30.46）, （207.67 ±27.32）, （124.25 ± 16.89） ng/L, P 〈 0.01 ]. As compared with that in hypoxia group, hypoxic pulmonary artery hypertension was decreased in hypoxia ＋ stellate block group （P 〈 0.05）, CGRP was increased （P 〈 0.01）, and endothelin-1 was decreased remarkably （P 〈 0.05）. ② Level of BVE-NOS of the experimental rabbits was higher in stellate block group, hypoxia group and hypoxia ＋ stellate block group than that in the normal control group [（0.25±0.06）, （0.27±0.07）, （0.46± 0.12）, （0.14±0.03）, P 〈 0.05], and NOS level was higher in the hypoxia ＋ stellate block group than that in hypoxia group （P 〈 0.05）. CONCLUSION： Mean arterial pressure is decreased in rabbits with hypoxic pulmonary artery hypertension after stellate block and level of endothelin-1 is also decreased; however, levels of CGRP and NOS are increased respectively.

Antiapoptotic Mechanism of Insulin in Reoxygenation-induced Injury in Cultured Cardiomyocytes of Neonatal Rats

To examine the protective effect of insulin on reoxygenation-induced injury and explore the underlying mechanisms, the model of anoxia/reoxygenation （A/R） injury was established by inducing anoxia for 2 h and reoxygenation for 4 h in cultured cardiomyocytes of neonatal rats. The rats were randomized to four groups receiving vehicle, insulin, LY294002, insulin plus LY294002 at the onset of reoxygenation after 2 h of anoxia. At the end of reoxygenation of 4 h, activity of lactate dehydrogenase （LDH） and content of malondialdehyde （MDA） were spectrophotometrically determined, apoptosis of cardiomyocytes were detected by using TUNEL and DNA Ladder, and Western blotting was employed to examine the expression of phosphorylated Akt in all groups. Our results showed that compared with vehicle-treated group, activities of LDH, contents of MDA, apoptosis index （AI） were significantly decreased, and expression of phosphorylated Akt was increased significantly in insulin-treated group. However, changes in LDH, MDA, AI and phosphorylated Akt resulting from insulin were attenuated or abolished by LY294002 （PI3K inhibitor）. These data strongly suggest that early administration of insulin at reoxygenation protects cardiomyocytes from reoxygenation-induced apoptosis through PI3K/Akt signaling pathway.

Protective Effects of Radix Astragali against Anoxic Damages to in vitro Cultured Neurons

To study the protective effects of radix astragali against anoxic damages to in vitro cultured neurons in rats, NaCN was used to develop a hypoxic model of in vitro cultured neurons from newborn rat cerebral cortex. The cellular morphology, A value (cell survival number) and effluxes of lactate dehydrogenase(LDH) and K+ from cells were measured in the radix astragali group and the control group respectively. After 48 h of anoxia, A value was decreased from 0. 325± 0. 031 before anoxia to 0. 145± 0. 011, the effluxes of LDH and K+ were increased from 65. 80± 2. 90 U/L and 5. 23 ± 0. 11mmol/L before anoxia to 148. 80± 8. 40 U/L and 7. 31 ± 0. 18 mmol/L, respectively. It was found that in the anoxic circumstance in the Radix astragali group, the mophological changes were mild, the effluxes of LDH and K+ were decreased and A value increased as compared with those in the control group. It was suggested that Radix astragali could protect the cultured rat neurons against anoxic damages in the anoxic circumstance.

Hydrogen Peroxide Alleviates Hypoxia during Imbibition and Germination of Bean Seeds (<i>Phaseolus vulgaris</i>L.)

Bean seeds (Phaseolus vulgaris L. cv. Tendergreen) were imbibed in water to examine the effects of hypoxia during imbibition and subsequent germination. Hypoxic conditions occurred when seeds were imbibed in water for 24 h or longer and resulted in severe reduction of hypocotyl elongation and stem growth during subsequent germination under non-limiting oxygen conditions. Under continued hypoxic conditions, bean seeds failed to germinate, however, this was reversed in the presence of hydrogen peroxide (20 mM) in the medium. Furthermore, imbibition of seeds in the presence of hydrogen peroxide overcame the adverse hypoxic effects on hypocotyl elongation and stem growth. Exogenous hydrogen peroxide increased the dissolved oxygen levels in the germinating medium, and catalase and transition metal ions such as Fe2+, Cu2+ and Mn2 helped to facilitate the production of oxygen from hydrogen peroxide. In these catalysts, catalase played a major role in the decomposition of hydrogen peroxide as demonstrated by the use of a catalase inhibitor, 3-amino-1, 2, 4-triazole, which reversed the positive effects produced by hydrogen peroxide on germination of seeds under hypoxic conditions. The results show that imbibition is sensitive to oxygen deficits which affect subsequent hypocotyl growth and seedling performance. The adverse effects of hypoxia on germination of bean seeds can be overcome by exogenous hydrogen peroxide.

Screening and evaluation of chilli(Capsicum annuum L.)genotypes for waterlogging tolerance at seedling stage

Waterlogging is an illustrious abiotic stress and the constrictions it enforces on plant roots have negative effects on growth and development.This study was undertaken to investigate waterlogging stress tolerant potential in chilli(Capsicum annum L.)genotypes through evaluating morphological,physiological,biochemical and anatomical parameters.Thirty-five days old seedlings of 10 chilli genotypes were exposed to waterlogging stress maintaining water height 3–5 cm over the soil surface artificially for three days.This duration(36–38 DAE)was termed as waterlogging period,and subsequent withdrawal of waterlogging condition(39–45 DAE)was regarded as a recovery phase.Based on their survival performance,two tolerant genotypes viz.,SRC-517 and BARI morich-2 and two susceptible genotypes viz.,AHM-206 and RI-1(6)were selected for studying stress tolerance mechanism.Under waterlogging,however,both genotypes(tolerant and susceptible)exhibited reduced root shoot length,dry weight ratio,petiole weight and leaf area,and noticeable reduction regarding these parameters was observed in susceptible genotypes.Moreover,tolerant genotypes displayed a higher recovery than susceptible genotypes after removal of waterlogging stress.Lower reduction of leaf area and photosynthetic pigments as well as higher reduction of relative water content(RWC)were noticed in susceptible genotypes.Higher accumulation of proline and total antioxidant capacity(TAC)during waterlogging condition in tolerant genotypes suggested lower oxidative damage.Although both genotypes lost total soluble sugar(TSS)relative to control at waterlogging stress,better performance was recorded in tolerant genotypes.During the period after the removal of extra water,a similar genotypic response in terms of TSS gain was seen.Undoubtedly,under flooding conditions,the development of aerenchyma cells in tolerant genotypes is a means of tolerance mechanism for long-term survival.Thus,the morpho-physiological and biochemical changes help to understand the tolerance mechanism in chilli under waterlogging stress.

Effects of the Medium Conditioned by Endothelial Cells under Hypoxic Condition on the Phenotype of Porcine Pulmonary Arterial Smooth Muscle Cells

The effects of the medium conditioned by endothelial cells under hypoxic condition on the phenotype modulation of pulmonary artery smooth muscle cells(PASMCs) were investigated by using cell culture and morphometrical analysis. The results showed that the number of diploid cells and alpha-sm-actin of PASMCs in the hypoxic endothelial cell conditioned medium group (HECCM) was lower and the myofibrilles were even less than that in normal endothelial cell conditioned medium group(NECCM). On the contrary,the volume density of rough endoplasmic reticulum(RER) and mitochondria of PASMCs in the HECCM group was higher than that in the NECCM group,i.e.altering from a contractile type to a synthetic type. However, under direct hypoxic condition for 24 h, the phenotype of cultured-PASMCs remained unchanged, i. e. retained contractile type.It suggests that the HECCM can induce phenotype modulation of PASMCs, may be mediated by the pulmonary artery endothelial cells(PAECs) which can secrete some cytokins affecting the PASMCs.

Nerve Growth Factor Inhibits Gd^(3+)-sensitive Calcium Influx and Reduces Chemical Anoxic Neuronal Death

To investigate whether glutamate and voltage-gated calcium channels-independent calcium influx exists during acute anoxic neuronal damage and its possible relationship to neuronal protective function of NGF. In in vitro model of acute anoxia, hippocampal cultures from newborn rats were exposed to 3 mmol/L KCN. Changes of intracellular Ca^2＋ concentration （[Ca^2＋]i） were monitored by con-focal imaging and cell viability was assayed by PI and cFDA staining. The results showed that after treatment with primary hippocampal cultures with 3 mmol/L KCN for 15 min, [Ca^2＋]i was significantly increased 6.27-fold compared to pre-anoxia level and 73.3% of the cells died. When combination of 20 μmol/L MK-801 （glutamate receptor antagonist）, 40 μmol/L CNQX （AMPA receptor antagonist） and 5 μmol/L nimodipine （voltage-gated calcium channel antagonist） （hereafter denoted as MCN） were administrated to hippocampal cultures, levels of [Ca^2＋]i and cell death rate induced by KCN were partially reduced by 35.9% and 47.5% respectively. However, Gd^3＋ （10 μmol/L） almost completely blocked KCN-mediated [Ca^2＋]i elevation by 81.9% and reduced neuronal death by 88.8% in the presence of MCN. It is noteworthy that NGF, used in combination with MCN, inhibited KCN-induced [Ca^2＋]i increase by 77.4% and reduced cell death by 87.1%. Only PLC in- hibitor U73122 （10 μmol/L） abolished NGF effects. It is concluded that Gd^3＋-sensitive calcium influx, which is NMDA （glutamate receptor） and voltage-gated calcium channels-independent, is responsible for acute anoxic neuronal death. NGF can inhibit Gd^3＋-sensitive calcium influx and reduce anoxic neuronal death through activating PLC pathway.

Land Use Changes Do Not Rapidly Change the Trophic State of a Deep Lake. Amvrakia Lake, Greece

The study of physicochemical and biological parameters can assess the trend of a lake’s trophic state. A trophic state index (TSI) was used to assess eutrophication of LakeAmvrakia. Total phosphorus and chlorophyll concentrations that recorded were generally at the same level with those recorded in previous years, a fact which indicates that lake’s trophic state did not change. But in the past ten years, agricultural uses have been modified by almost 25% of the catchment area, because of the major reduction of tobacco cultivation. One year of monthly monitoring, in nine sampling stations can report this result. Even if the catchment is small and the agricultural areas are the 47% of the basin, the water quality of the lake did not change. The trophic state is stable probably because the lake is deep monomictic, and seasonally anoxic. For this reason internal phosphorus contribution is very important in the deep hypolimnion.