Characterization of the osmotic-stress response inSaccharomyces cerevisiae: osmotic stress and glucose repression regulate glycerol-3-phosphate dehydrogenase independently

Micro-organisms have developed systems to adapt to sudden changes in the environment. Here we describe the response of the yeastSaccharomyces cerevisiae to osmotic stress. A drop in the water activity (a_w) of the medium following the addition of NaCl led to an immediate shrinkage of the cells. During the 2 h following the osmotic shock the cells partially restored their cell volume. This process depended on active protein synthesis. During the recovery period the cells accumulated glycerol intracellularly as a compatible solute and very little glycerol was leaking out of the cell. We have investigated in more detail the enzymes of glycerol metabolism and found that only the cytoplasmic glycerol-3-phosphate dehydrogenase was strongly induced. The level of induction was dependent on the yeast strain used and the degree of osmotic stress. The synthesis of cytoplasmic glycerol-3-phosphate dehydrogenase is also regulated by glucose repression. Using mutants defective in glucose repression (hxk2), or derepression (snf1), and with invertase as a marker enzyme, we show that glucose repression and the osmotic-stress response system regulate glycerol-3-phosphate dehydrogenase synthesis independently. We infer that specific control mechanisms sense the osmotic situation of the cell and induce responses such as the production and retention of glycerol.     

Stretch activation and myogenic oscillation of isolated contractile structures of heart muscle

Summary Glycerinated or freeze-dryed fibre bundles of heart muscles (papillary and trabecular muscles of rabbit or guinea pig) show in ATP-salt solution with about 10^–6M Ca²⁺ an active, delayed tension increment after quick or sinusoidal stretching. The active tension increase is completely different from the passive tension increment caused by stretching of the elastic structures of the muscle; this well known length dependence of tension is also in phase with the length changes (or the tension-phase preceeds the length-phase in visco-elastic bodies). On the other hand, the active tension increase is delayed with respect to the length change; this can be observed very well after rectangular changes in length. The delayed activation of the contractile bonds at stretch and the delayed deactivation at shortening induce the muscle-during sinusoidal length changes in a characteristic frequency range-to produce power output. The frequency range corresponds to the heart beat frequency of the living muscle. Temperature rise and inorganic phosphate accelerate, Mg-ions and ADP retard the contraction speed. Ca-ions influence only the amount of the isometric tension, but not the contractile velocity.Supported by the Deutsche Forschungsgemeinschaft (Grant RU 154/3).     

甘油蔗糖液对哺乳动物桑椹胚的渗透反应及冻存效果研究

为了提供快速冷冻前胚胎发生部分脱水的科学依据，我们观察了家兔桑椹胚在冷冻保护液中的体积变化。当桑椹胚置于仅含３．０ｍｏｌ／Ｌ或４．０ｍｏｌ／Ｌ甘油液中，桑椹胚立即皱缩，２ｍｉｎ时体积为等渗时体积的５８．９％或５９．６＾％，１０ｍｉｎ时桑椹胚体积达到等渗量的９０．８％或７６．９％，将这些桑椹胚接着移入含３．０ｍｏｌ／Ｌ或４．０ｍｏｌ／Ｌ甘油加０．２５ｍｏｌ／Ｌ蔗糖保护液中，桑椹胚再次发生皱缩主膨大变     

Percutaneous Procedures for Trigeminal Neuralgia

Microvascular decompression is the gold standard for the treatment of trigeminal neuralgia (TN). However, percutaneous techniques still play a role in treating patients with TN and offer several important advantages and efficiency in obtaining immediate pain relief, which is also durable in a less invasive and safe manner. Patients’ preference for a less invasive method can influence the procedure they will undergo. Neurovascular conflict is not always a prerequisite for patients with TN. In addition, recurrence and failure of the previous procedure can influence the decision to follow the treatment. Therefore, indications for percutaneous procedures for TN persist when patients experience idiopathic and episodic sharp shooting pain. In this review, we provide an overview of percutaneous procedures for TN and its outcome and complication.     

甘油对突发性聋的治疗作用

目的　观察甘油对突发性聋的治疗作用。方法　将 6 0例突聋者分成甘油治疗组 (A组 )和对照组 (B组 ) ,A组除加服 5 0 %甘油盐水外 ,其余治疗与B组相同 ,包括高压氧、扩血管药、能量制剂和激素治疗。并分别于治疗前和治疗后 10天测试患者的听力。结果　治疗前A组和B组的平均听阈分别为 70 .6 7± 2 0 .43dBHL和 6 7.5 8± 36 .18dBHL(P >0 .0 5 ) ,治疗后两组听力平均提高分别为 30 .0 9± 2 0 .43dB和 18.42± 18.0 5dB(P <0 .0 5 )。结论　甘油有助于提高突聋的治疗效果     

甘油对梅尼埃病患者前庭诱发的肌源性电位的影响

目的通过梅尼埃病患者前庭诱发的肌源性电位(vestibulare voked myogenic potential,VEMP)在甘油试验前后的变化情况,了解本项检查在梅尼埃病诊断中的意义。方法对明确诊断为梅尼埃病的10例患者进行甘油试验,比较甘油试验前后前庭诱发的肌源性电位的变化。甘油试验VEMP观察时间段选择两点,服用甘油前及服用甘油后3小时的振幅变化作为指标。结果8例单侧梅尼埃病,其中5例振幅改善(2例振幅增加,3例振幅从无到有),3例甘油试验后VEMP的振幅变差。2例双侧梅尼埃病,1例甘油试验后VEMP振幅从无到有,1例VEMP振幅改善。结论梅尼埃病患者甘油试验后,VEMP变化有以下三种情况:①从无到有;②引出的振幅降低;③引出的振幅提高。甘油试验纯音听力检查结合VEMP的甘油试验有助于梅尼埃病的诊断。     

血清总甘油测定基质效应的研究

目的 评价28种质控血清或校准物在8种总甘油常规检测系统下的基质效应,并评价常规系统校准的准确性.方法 以同位素稀释液相色谱串联质谱测定m清总甘油的方法为对比方法,用甘油氧化酶法的8种常规测定系统为待评价方法,测定20份人新鲜血清和28种制备物中的总甘油.将两法测定人新鲜血清的结果作直线回归,求得Y值双侧95%的预测区问,评价制备物的基质效应.通过分析新鲜血清样本的测定结果评价常规系统校准的准确性.结果 制备物在进口A、B、C系统和国产D系统巾表现正基质效应,进口D系统正、负基质效应均有以正效应为主,国产A、B系统正、负基质效应均以负效应为主,只有1个制备物对国产C系统有较弱的基质效应.同对比方法相比,国产A、D系统存在正校准偏差,进口A、B、C、D和国产B系统1竽在负偏差,国产C系统不存在校准偏差.结论 我国血清总甘油的部分常规检测系统存在校准偏差,部分质控物和校准物存在基质效应.为实现检验结果的准确性和实验室问的可比性,临床标准化工作势在必行.     

Le «remote masking»: un test de surdité de transmission cochléaire: Remote Masking as a Test of Cochlear Conductive Hearing Losses

The authors studied the remote masking (RM) in patients with Menière's disorder during the hearing loss fluctuations produced either by the disorder or by the glycerol test (Klockhoff). The RM was recorded for pulsed tones of 250, 500 and 1 000 Hz; the masker was a continuous narrow-band noise centered at 3 000 Hz, with 305 Hz (2 875–3 180 Hz) bandwidth, delivered at an overall level of 98 dB SPL. The results showed that the RM decreases during the acute phase, i.e. when the hearing loss increases, and, increases if the glycerol tests do not significantly modify the RM value. They seem to confirm the hypothesis that the RM may be due to a mechanical effect in the internal ear and suggest the possibility of using the RM as a test of end-organ rigidity.

Résumé

Les auteurs ont étudié le RM sur des sujets atteints de maladie de Menière pendant les fluctuations du déficit auditif produites par les crises ou provoquées par le test au glycérol selon Klockhoff. Le RM a été enregistré pour des tons de 250, 500 et 1 000 Hz interrompus deux fois par seconde et d'une durée de 250 ms; le son masquant était un bruit à bande étroite centrée sur la fréquence de 3 000 Hz, d'une largeur de 305 Hz (2 875–3 180 Hz), envoyé en continu à. 98 dB SPL. Les résultats ont montré que la valeur en décibels du RM diminue pendant les crises, lorsque le deficit auditif augmente; au contraire, le RM augmente au moment oú le glycérol produit une amélioration des seuils d'audition. Pour des tests au glycérol négatifs, nous n'avons observé aucune variation marquée du RM. Ces résultats vérifient l'hypothèse de l'origine mécanique du RM et suggèrent la possibilité d'utiliser le RM pour tester la rigidité de la membrane basilaire.