The effect of simulated altitude (500 mm Hg) on urine acid mucopolysaccharides excretion in normal rats

The influence of simulated altitude of 500 mm Hg for 5 hr on the daily urinary excretion of acid mucopolysaccharides was investigated in 10 male adult rats. The simulated altitude applied for the first time caused a statistically significant (p < 0.05) increase in the excretion of acid mucopolysaccharides on the day of the experiment. The same trend was observed when simulated altitude was applied for the second and third time but the values were not statistically different from the control values, probably due to the small number of investigated animals. On the day following that of exposure to simulated altitude the excretion decreased to approximately control levels.

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Zusammenfassung Es wurde der Einfluss von 5 Stunden Aufenthalt in simulierter Höhe (500 mm Hg) auf die tägliche Ausscheidung der sauren Mucopolysaccharide im Rattenharn untersucht. Die Mucopolysaccharidausscheidung war im Anschluss an die Höhenexponierung in einem Experiment signifikant erhöht. Die gleiche Tendenz wurde in zwei weiteren Experimenten beobachtet,doch waren die Unterschiede nicht signifikant.Einen Tag nach der Höhenexponierung kehrte die erhöhte Ausscheidung annähernd zur Norm zurück.

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Resume On a étudié sur 10 rats adultes l'influence de leur exposition pendant 5 heures à une altitude simulée de 500 mm Hg sur l'excrétion des mucopolysaccharides acides urinaires. On a constaté une augmentation statistiquement significative du taux des mucopolysaccharides acides urinaires pendant la journée d'exposition à l'altitude simulée pour la première fois.Une tendance analogue a été observée sous l'influence d'expositions identiques appliquées pour la seconde et la troisième fois,mais les taux n'étaient alors pas statistiquement différents de ceux des contrôles, probablement à cause du trop petit nombre d'animaux examinés. Au cours des 24 heures suivant la journée d'exposition à l'altitude simulée, l'excrétion urinaire de ces substances est redescendue à des nivaux approximativement égaux à ceux des contrôles.

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Recipient of a WHO Scholarship, founded by the Israeli Government, held at the Rogoff-Wellcome Med.Res.Institute, Beilinson Hospital, Petah Tikva.     

The effect of simulated altitude (500 mm Hg) on urine acid mucopolysaccharides excretion in hypophysectomized rats

The influence of simulated altitude of 500 mm Hg for 5 hr on the daily excretion of urinary acid mucopolysaccharides in hypophysectomized rats was investigated. Hypophysectomy per se caused a decreased in the excretion of acid mucopolysaccharides. Under the influence of simulated altitude the rats showed non significantly diminished excretion of acid mucopolysaccharides on the day of the experiment. These results were in contrast to those obtained with normal rats.

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Zusammenfassung Es wurde der Einfluss von simulierter Höhe (500 mm Hg) auf die Ausscheidung von sauren Mucopolysacchariden im Harn von hypophysektomierten Ratten untersucht. Nach Hypophysektomie war die Mucopolysaccharidausscheidung vermindert. Nach Höhenexponierung wurde eine Tendenz zur weiteren Verminderung der M.-Ausscheidung beobachtet. Das steht im Gegensatz zu den Ergebnissen mit gesunden Ratten.

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Resume On a étudié l'influence d'une exposition pendant 5 heures à une altitude simulée de 500 mm Hg sur l'excrétion urinaire de mucopolysaccharides par des rats dont on avait retranché l'hypophyse. L'hypophysectomie a pour sa part causé une diminution des mucopolysaccharides urinaires. Sous l'influence de l'altitudes simulée les rats présentent une tendance à la diminution du taux étudié, mais seulement le jour de l'application de la pression réduite. Ces résultats sont en contradiction avec ceux obtenus chez des rats normaux.

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Recipient of a WHO scholarship, founded by the Israeli Government, held at the Rogoff-Wellcome Med.Res.Instistute, Beilinson Hospital, Petah Tikva.     

Complexation of Hg with phytochelatins is important for plant Hg tolerance

Three-week-old alfalfa (Medicago sativa), barley (Hordeum vulgare) and maize (Zea mays) were exposed for 7 d to 30 μm of mercury (HgCl(2) ) to characterize the Hg speciation in root, with no symptoms of being poisoned. The largest pool (99%) was associated with the particulate fraction, whereas the soluble fraction (SF) accounted for a minor proportion (<1%). Liquid chromatography coupled with electro-spray/time of flight mass spectrometry showed that Hg was bound to an array of phytochelatins (PCs) in root SF, which was particularly varied in alfalfa (eight ligands and five stoichiometries), a species that also accumulated homophytochelatins. Spatial localization of Hg in alfalfa roots by microprobe synchrotron X-ray fluorescence spectroscopy showed that most of the Hg co-localized with sulphur in the vascular cylinder. Extended X-ray Absorption Fine Structure (EXAFS) fingerprint fitting revealed that Hg was bound in vivo to organic-S compounds, i.e. biomolecules containing cysteine. Albeit a minor proportion of total Hg, Hg-PCs complexes in the SF might be important for tolerance to Hg, as was found with Arabidopsis thaliana mutants cad2-1 (with low glutathione content) and cad1-3 (unable to synthesize PCs) in comparison with wild type plants. Interestingly, high-performance liquid chromatography-electrospray ionization-time of flight analysis showed that none of these mutants accumulated Hg-biothiol complexes.     

G-quadruplex DNAzyme-based Hg2+ and cysteine sensors utilizing Hg2+-mediated oligonucleotide switching

A simple and sensitive colorimetric Hg(2+) detection method is reported, based on the Hg(2+)-mediated structural switch of an unlabeled oligonucleotide strand. In the absence of Hg(2+), the oligonucleotide strand forms a stem-loop. A G-rich sequence in the strand is partially caged in the stem-loop structure and cannot fold into a G-quadruplex. In the presence of Hg(2+), T-Hg(2+)-T coordination chemistry leads to the formation of another stem-loop structure and the release of the G-rich sequence. The released sequence folds into a G-quadruplex, which binds hemin to form catalytically active G-quadruplex DNAzymes. This is detected as an absorbance increase in a H(2)O(2)-2,2'-azinobis(3-ethylbenzothiozoline)-6-sulfonic acid (ABTS) reaction system using UV-vis absorption spectroscopy. This simple colorimetric sensor can detect aqueous Hg(2+) at concentrations as low as 9.2 nM with high selectivity. Based on the strong binding interaction between Hg(2+) and the sulfur-containing amino acid cysteine (Cys), and the competition between Cys and a oligonucleotide for Hg(2+), the proposed Hg(2+)-sensing system can be further exploited as a Cys-sensing method. The method has a detection limit for Cys of 19 nM.     

南极生物粪对汞的生物放大作用

首次报道了南极地区金图企鹅、阿德利企鹅、黑背鸥和巨海燕 4种海鸟 ,以及象海豹、威德尔海豹、毛皮海狮等 3种海豹新鲜粪便中的全 Hg含量 ,并对比了该区风化土壤的 Hg含量 ,其中 Hg含量水平依次为 :土壤背景值 <黑背鸥粪 <金图企鹅粪 <阿德利企鹅粪 <威德尔海豹粪 <象海豹粪 <巨海燕粪 <毛皮海狮粪 ,可见 ,相对于背景土壤生物粪明显富集 Hg元素。此外 ,结合上述粪便样品的 δ15 N测定结果 ,讨论了南极生物粪对 Hg的生物放大作用。研究表明 ,随着 δ15 N升高 ,即生物营养级的升高 ,其粪便的全 Hg含量有逐步增高的趋势 ,这证实了生物粪和生物肌体一样存在对 Hg的生物放大作用。文中还对南极阿德雷岛一个经过企鹅粪污染的 Y2湖泥芯剖面上 15个样品的 2 6种元素进行了聚类分析 ,结果表明 ,沉积物中的汞和企鹅粪的标型元素具有同源性 ,即沉积物中的汞主要是由企鹅粪带入的 ,由于生物粪对汞的生物富集作用 ,生物粪的混入会造成湖泊沉积物中汞含量的增高     

21毫米人造心脏瓣膜泵的设计及研制

为了研究能够长期置入主动脉瓣环的左心室辅助装置,研制出直径21毫米重27克可植入的主动脉瓣膜泵.装置包括一个转子和一个定子.转子由驱动磁钢和叶轮组成;定子装有带铁心的电机线圈和出口导叶.装置被置於主动脉瓣位置,所以不占用额外的解剖空间.血泵能像自然心脏一样直接将血液由心室输送到主动脉,不需要连接管道和旁路,因此对自然生理循环的干扰可以减到最低.血泵流量由最大到零周期变化.血液动力学测试表明,当血泵转速为17500转/分钟时,可以产生流量5升/分钟、压力增益50毫米汞柱的血流;同一转速下,当流量为零时,血泵能保持主动脉舒张压为80毫米汞柱.