Age-Related Alterations in Antioxidant Enzymes, Lipid Peroxide Levels, and Somatosensory-Evoked Potentials: Effect of Sulfur Dioxide

The effect of sulfur dioxide (SO₂) on somatosensory-evoked potentials (SEPs), thiobarbituric acid reactive substances (TBARS), and the activities of Cu,Zn-superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) were investigated in young (3 months), middle-age (12 months), and old (24 months) Swiss male albino rats. Ten ppm SO₂ was administrated to the animals of SO₂ groups in an exposure chamber for 1 h/day × 7 days/week × 6 while control groups were exposed to filtered air in the same condition. SO₂ exposure caused increased levels of brain Cu,Zn-SOD activity and decreased levels of brain GSH-Px activity in all experimental groups with respect to their corresponding control groups. Brain CAT activities were unaltered. Brain TBARS levels of all SO₂-exposed groups were significantly increased in comparison with their respective control groups. The mean latencies of P₁, P₂, and N₂ components in the older group were either significantly different from the young or from the middle-age groups. The mean latency of the N₁ component in the older group and that of P₁ and N₁ in the middle-age group were significantly increased compared with the young group. SO₂ exposure caused the prolongation of all components in the young group, whereas it affected only the P₂ component in the middle-age group, but it did not result in any latency change in the older group in comparison with their corresponding control groups. Received: 22 December 1998/Accepted: 7 April 1999     

Inhibition kinetics of human serum butyrylcholinesterase by Cd2+, Zn2+ and Al3+: comparison of the effects of metal ions on cholinesterases

Butyrylcholinesterase (BChE, EC 3.1.1.8) has been purified about 6600-fold from human serum with a procedure including ammonium sulfate fractionation (55-70%) with acid step at pH 4.5 and procainamide-Sepharose 4B affinity chromatography. The purified enzyme exhibited negative cooperativity with respect to butyrylthiocholine (BTCh) binding at pH 7.5. Ks was found to be 0.128 +/- 0.012 mM. Inhibition kinetics of the enzyme by Cd2+, Zn2+ and Al3+ were studied in detail. The 1/v vs 1/[BTCh] plots in the absence (control plot) and in the presence of different concentrations of cations intersected above 1/[BTCh]-axis. The data were analyzed by means of a nonlinear curve fitting program. The results demonstrated that all of the three cations are the linear mixed-type inhibitors of BChE. Ca2+ and Mg2+ had no effect on the enzyme activity in the experimental conditions. But when the enzyme was inhibited by 0.5 mM Cd2+ or Zn2+, Ca2+ and Mg2+ partially reactivated the inhibited allosteric form of BChE. Results were compared with data obtained from brain BChE purified from sheep.     

A study on impact and tensile strength of acrylic resin filled with short ultra-high molecular weight polyethylene fibers

In dentistry, acrylates have been used for preparing denture bases for 50 years. Although polymethylmethacrylates (PMMA) are known to be an ideal base material, they possess some undesirable mechanical properties, especially their impact strength and tensile strength, which appear to be unsatisfactory for some applications. Additives and fibers have therefore been used to enhance and improve these properties over the last two decades. The present article describes the mechanical properties, impact and tensile strength of PMMA reinforced with chopped ultra-high molecular weight polyethylene fiber (6 mm long). It was found that, although the processing involved for high loading of fibers into the PMMA was difficult, the resulting improvement of impact strength was substantial.     

PT和APTT标本留存时间与结果稳定性关系

目的探讨标本的待测时间对凝血酶原时间（PT）和活化部分促凝血酶原时间（APTT）试验结果的影响。方法：在室温下分别于采样后即刻、2、4、6、24h测定了40例志愿者的PT、AFTT,同时进行了血浆留存和全血留存结果的比较。结果：6h内无论全血留存标本还是血浆留存标本,其PT值和APPT值与初始值相比均无明显变化（P＞0．05）;24h全血留存标本PT值略升高（P＞0．05）,血浆留存标本较初始值延长14％,有显著差异（P＜0．05）。APTT值两类标本在6h内与初始值相比也无明显变化（P＞0．05）,24h均明显延长（P＜0．05）。结论：血浆留存标本或全血留存标本PT或APTT测定宜在采集标本后6h内完成。     

电教多媒体数据库管理系统的设计

目的：设计研制一个面向院校电教中心的多媒体数据库管理系统,以便用现代信息技术管理电教中心众多的信息资料。方法：在国产MIS开发平台Multibase2．0上,用原型法进行无编程设计开发。结果：制作的数据库管理系统运行稳定,操作方便,维护简单,查询功能新颖而强大,基本功能设计具有较强的针对性,能够满足电教中心日常工作的需要。结论：采用国产无编程MIS开发平台Multibase完全可以开发出实用的多媒体数据库管理系统,本数据库管理系统可向军内外院校推广使用。     

<伤寒论>栀子豉汤证治剖析

《伤寒论》中以栀子豉汤为代表方的栀子豉汤类方,由于在理论上对其证治缺乏充分的认识,致使在临床上不能如桂枝剂、柴胡剂等经方那样发挥其应有的作用。本文提出栀子豉汤所治主证是热郁胃中所致的“心中懊”而非热扰胸膈的“虚烦”,而“心中懊”实乃胃中嘈杂。并进而分析了从热郁胃中至阳明腑实证与阳明湿热发黄证之间存在的内在病机演变过程,指出栀子豉汤是治疗阳明热证之第一法。     

Reversal of Cerebral Vasospasm by the Nitric Oxide Donor SNAP in an Experimental Model of Subarachnoid Haemorrhage

The constant release of nitric oxide (NO) is essential to maintain basal cerebrovascular tone. Oxyhaemoglobin, liberated by lysis of red blood cells after subarachnoid haemorrhage binds NO and prevents its entry into vascular smooth muscle cells. While endothelium-dependent vasoconstriction is preserved, decreased levels of NO inhibit endothelium-dependent relaxation and may cause vasospasm. S-nitrosothiols are potent vasodilators and precursors of NO. The authors' aim was to determine whether S-nitroso-N-acetylpenicillamine (SNAP), a stable S-nitrosothiol compound, could reverse vasospasm in an experimental vasospasm model in rabbit. Experimental subarachnoid haemorrhage (SAH) was induced in 37 New Zealand white rabbits. The animals were divided into four groups. Control (no SAH), SAH only, SAH plus saline and SAH plus SNAP. SNAP (15 micrograms/kg/min) or 0.09% saline (equal volume) was infused 46 hours after induction of SAH. All animals were killed by perfusion fixation 48 hours after SAH occurred. Basilar arteries were removed, sectioned and their cross sectional areas were evaluated in a blind manner, by light microscopy and by using computer assisted morphometry. Experimental SAH elicited vasospasm in all animals of SAH only and SAH plus saline group. In animals treated with SNAP, arterial narrowing was markedly attenuated without producing systemic hypotension. This widening achieved statistical significance when compared to the arteries of the SAH only and SAH plus saline group (p < 0.01). This study indicates that the NO donor SNAP is a potentially useful drug to reverse cerebral vasospasm due to SAH.