Does glutathione-S-transferase dethiolate lens protein-thiol mixed disulfides?-A comparative study with thioltransferase.

Protein S-thiolation is a process in which under oxidative stress, vulnerable sulfhydryl groups of proteins are conjugated to non-protein thiols such as glutathione (GSH) or cysteine resulting in the formation of protein-thiol mixed disulfides, protein-S-S-glutathione (PSSG) and protein-S-S-cysteine (PSSC). This process spontaneously disrupts the redox homeostasis of the cells, which in turn leads to functional disturbances in the respective tissue. In the ocular lens, such modification of proteins may trigger a cascade of events starting with the alteration of protein conformation, protein/enzyme deactivation, protein-S-S-protein aggregation and eventually lens opacification or cataract. Generally, the first line of defense system in the cells protects the lens proteins against such damage. Recent studies in our laboratory have shown that in addition to this defense system, lens cells also possess a well developed system to repair the oxidative damage to the lens proteins. We have identified this repair system as thioltransferase (TTase) and have proved that TTase by its dethiolase activity reverses the protein S-thiolation process which returns the oxidatively damaged lens proteins/enzymes to their original reduced state and restores their physiological functions. We investigated if this repair mechanism was mediated by enzymes other than TTase. We studied glutathione S-transferase (GST) and report here for the first time the cloning, high level expression, and purification of human lens mu and pi isoforms of GST. A comparative study of recombinant human lens TTase and GST (mu and pi) on their dethiolating abilities using lens crystallin-thiol mixed disulfides showed that the lens TTase is 60-70% more efficient in the dethiolation/repair process than GST. When TTase and GST were tested in conjunction for the dethiolation of thiol mixed disulfides, there was no significant enhancement of dethiolase activity. These findings suggest that TTase by itself is an efficient enzyme in the dethiolation/repair process and hence can be considered a crucial system to counteract oxidative stress in the lens.     

Modulation of Ca2+/calmodulin-dependent protein kinase II activity by acute and chronic morphine administration in rat hippocampus: differential regulation of alpha and beta isoforms

Calcium/calmodulin-dependent protein kinase II (CaMK II) has been shown to be involved in the regulation of opioid receptor signaling. The present study showed that acute morphine treatment significantly increased both Ca2+/calmodulin-independent and Ca2+/calmodulin-dependent activities of CaMK II in the rat hippocampus, with little alteration in the protein level of either alpha or beta isoform of CaMK II. However, chronic morphine treatment, by which rats were observed to develop apparent tolerance to morphine, significantly down-regulated both Ca2+/calmodulin-independent and Ca2+/calmodulin-dependent activities of CaMK II and differentially regulated the expression of alpha and beta isoforms of CaMK II at protein and mRNA levels. Application of naloxone or discontinuation of morphine treatment after chronic morphine administration, which induced the withdrawal syndrome of morphine, resulted in the overshoot of CaMK II (at both protein and mRNA levels) and its kinase activity. The phenomena of overshoot were mainly observed in the beta isoform of CaMK II but not in the alpha isoform. The effects of both acute and chronic morphine treatments on CaMK II could be completely abolished by the concomitant application of naloxone, indicating that the effects of morphine were achieved through activation of opioid receptors. Our data demonstrated that both acute and chronic morphine treatments could effectively modulate the activity and the expression of CaMK II in the hippocampus.     

Haemodynamic consequences and uterine contractions following 0.5 or 1.0 litre crystalloid infusion before obstetric epidural analgesia

Purpose

The efficacy of infusion of 0.5 L and 1.0 L Ringer’s lactate (LR) to prevent hypotension during induction of obstetric analgesia was studied. The effect of the different fluid boluses on fetal heart rate (FHR) and frequency of uterine contractions were also determined.

Methods

Ninety-two ASA 1–2 parturients were randomized to receive 0.5 L (Group 1) and 1.0 L (Group 2) LR immediately before incremental epidural injections with lidocaine to achieve T₁₀ sensory block. Systolic blood pressure (SBP) was measured with an automated BP cuff every two minutes for 30 min after infusion of fluid bolus. Fetal heart rate monitoring and tocometry were used continuously. The number of uterine contractions were recorded 30 min before and 60 min after iv bolus.

Results

The SBP decreased in both groups, but there was no difference between groups in mean SBP or maternal heart rate. The incidence of hypotension (SBP < 90 mmHg or decrease of 20%) was 4% in both groups. The FHR record of a patient in Group 1 showed a single late deceleration, and a decrease in beat-to-beat variability occured in one patient in Group 2. A decrease in the frequency of uterine contractions of two or more contractions per 30 min was noted more frequently in Group 2 (P < 0.05). The duration of iv bolus was longer in Group 2 than Group 1 (18.8 ± 4.3 min vs 12.3 ± 4.5 min, P < 0.01).

Conclusion

Administration of 1.0 L LR iv does not provide added protection against maternal hypotension, and is associated with delay in providing pain relief and a risk of decreasing uterine contraction frequency.     

中药天花粉及其类似品的鉴别研究

本文对天花粉的使用概况作了介绍。据本草考证,自古以来中药天花粉的原植物主要来源即为栝楼Trichosanthes kirilowii Maxim.,但约自南宋之后天花粉的来源有所发展,因此天花粉商品又是多来源的。据作者在21省、区的100余市、县调查,国内约有30种植物根部曾作天花粉入药(包括地区习惯用药及混淆品)。本文对较多见的17种真伪天花粉列表简介,并对其中10种主要商品或混淆品的鲜根外形、药材或干燥品性状及显微特征(包括横切面及解离组织)进行了描述比较,同时找出各种外形及组织上的鉴别特征;列表比较其间的异同点。此外我们已经对其他6种天花粉进行了鉴别研究,待拉丁学名确定后再行报道。     

益母草的化学、药理和临床研究进展

查阅近20年有关文献，对益母草的化学成分、药理作用、临床应用研究进展进行综述。益母草主要含有生物碱类、黄酮类、二萜类、脂肪酸类、挥发油类等化合物；药理作用研究证明其具有调经止血、保护心肌缺血再灌注损伤、抗血小板聚集、降低血液黏度等作用；在临床上常用来治疗流产后出血、冠心病、心肌缺血、高黏血症、痛经等疾病。益母草具有广泛的药理活性，对其药效学物质基础进行深入研究和开发，将具有重要意义。     

复方益康唑滴耳液的制备及质量控制

目的：制备复方益康唑滴耳液并测定其含量。方法：以甘油和乙醇作为溶煤进行配制。采用双波长分光光度法在波长263.8nm和247.9nm处测定硝酸益康唑含量，在波长295.1nm处测定甲磺酸左氧氟沙星含量，并观察了该滴耳液的稳定性和刺激性。结果：硝酸益康唑和甲磺酸左氧氟沙星的平均回收率分别为99.6%(RSD=0.5%)和101.6%(RSD=0.4%)，刺激性小，稳定性好，结论：本制剂制备工艺简便，质控方法准确可靠，性质稳定，适应临床应用。     

红霉素环11,12-碳酸酯的体外抗菌活性研究

目的评 价红霉素环11，12-碳酸酯的体外抗菌活性。方法 采用琼脂平皿二倍稀释法测定国产和进口红霉素环11，12-碳酸酯对临床分离致病菌的体外抗菌作用，并与红霉素、罗红霉素、克拉霉素、地红霉素、阿奇霉素和乙酰螺旋霉素进行了比较。结果 国产和进口红霉素环11，12-碳酸酯对579株临床分离菌的抗菌活性相近，对革兰氏阳性菌和厌氧菌的抗菌活性比红霉素强2～8倍，优于罗红霉素、克拉霉素、地红霉索、阿奇霉素、乙酰螺旋霉素，但对革兰氏阴性菌的抗菌活性稍弱于阿奇霉素。红霉索环11，12-碳酸酯对金葡菌显示抑菌作用，对化脓链球菌在2～4倍MIC浓度时显示杀菌作用；红霉素环11，12-碳酸酯抗金葡菌和化脓链球菌的活性随着pH的增加而增强，接种量和血清浓度对国产红霉素环11，12-碳酸酯抗金葡菌和化脓链球菌的活性无明显影响。结论 红霉素环11，12-碳酸酯具有较强的体外抗菌活性，国产红霉素环11，12-碳酸酯抗菌活性与进口相近，优于红霉素、罗红霉素、克拉霉素、地红霉素、阿奇霉素和乙酰螺旋霉素。     

RP-HPLC法同时测定骨水泥释放液中头孢呋肟与头孢拉啶的浓度

目的 采用RP-HPLC法同时测定骨水泥中头孢呋肟与头孢拉啶的释放量。方法 以Irregular-H C₁₈柱(4.6mm×150mm)为固定相;甲醇-水(20∶80,含冰醋酸0.109mol/L)为流动相,pH值调至3.00;检测波长254nm。结果 测得头孢呋肟的线性范围为0.1～4.0μg·ml^-1,r=0.9999,头孢拉啶的线性范围为0.1～7.0μg·ml^-1,r=0.9998,日内日间RSD<5%。结论 方法简单、快速、准确。