The heat shock/oxidative stress connection

Involvement of free-radical oxidations in the aging process has been a topic of interest since Harman's original contribution. Because of the close association between aging and Alzheimer disease (AD) and the qualitative similarity in the neuropathology of both conditions, it has been proposed by many investigators that oxidative stress may be important in AD. If such modality of injury was indeed involved, one should expect to find markers of oxidation and heat shock (since free radicals are key mediators of heat-shock induction) in brains of patients with AD. In fact, several studies documented abnormal expression of antioxidant enzymes and heat-shock proteins (HSP) along with other markers of oxidation in AD brains. We showed that abnormally expressed antioxidant enzymes are topographically associated with senile plaques and neurofibrillary tangles, and that the activity of these enzymes is (contrary to what one would expect) markedly reduced. These findings have recently been confirmed by other investigators. Despite a large amount of evidence that suggests an association between oxidative stress and the pathogenesis of AD, it is not yet known whether oxidative stress is a cause or consequence of the disorder. Future research efforts regarding the oxidative stress hypothesis of AD should include attempts, at generating AD pathology by oxidative means in laboratory animals, determining the role and integrity of the heat-shock response in AD, as well as that of various antioxidant systems, growth factors, and hormones with antioxidant and neuroprotective properties.     

Effects of exercise on muscle activation and metabolism in multiple sclerosis

We investigated the role of metabolism in muscle fatigue during voluntary exercise in persons with mild multiple sclerosis (MS). Six MS and 8 healthy control subjects performed intermittent, progressive, isometric contractions of the ankle dorsiflexors, during which we measured maximum voluntary force (MVC), inorganic phosphate (Pi), phosphocreatine (PCr), and pH. During exercise. MVC fell sooner in MS, but by the end of exercise the relative decrease in MVC was similar in both groups. In contrast, at the end of exercise Pi/PCr increased to 1.86 ± 0.22 in controls but to only 0.66 ± 0.04 in MS (P < 0.01); likewise, pH was 6.75±0.04 in controls and unchanged (7.06 ± 0.04) in MS (P <0.01). The smaller metabolic change at the same relative exercise intensity suggests a failure of muscle activation that is present even in mild MS. Neurophsyiologic measures of activation indicated some central activation failure and no neuromuscular junction impairment in MS, and suggested that activation failure beyond the muscle membrane(excitation–contraction coupling) may be important in MS. We conclude that metabolic factors do not play a significant role in the development of muscle fatigue during voluntary exercise in mild MS. © 1994 John Wiley & Sons, Inc.     

In vitro evaluation of ablation parameters of normal and fibrous aorta using smooth excimer laser coronary angioplasty

A modified exeimer laser energy delivery system was used to irradiate 100 segments of normal and fibrous aorta in vitro. The laser beam was scanned into 8 fiber bundles consisting of 50 fibers each resulting in a reduction of the applied pulse energy. The total repetition rate was increased to 150 Hz in order to keep the repetition rate per fiber bundle close to 20 Hz and to minimize thermal injury. The results demonstrate that effective ablation (etch rate per 8 pulses > 2.0 μm) occurred at an energy fluency of 50 mJ/mm² in both normal and fibrous aorta. Tissue damage (carbonization, tissue separation, fissures, cracks, and vacuolization) was in a range of 100 ± 28 to 152 ± 30 μm for normal aorta and in a range of 57 ± 35 to 110 ± 39 μm for fibrous aorta. We conclude that effective ablation of normal and fibrous human aorta can be achieved by the application of smooth excimer laser coronary angioplasty. This improvement of excimer laser technology may result in a reduction of shock wave- and cavitation-induced damage leading to a reduction of tissue injury. However, this awaits further in vitro and in vivo confirmation. © 1993 Wiley-Liss, Inc.     

抗氧化剂等药物联合应用治疗烧伤休克的实验研究

我们用哈白兔以3％凝固气油致25％Ⅲ°烧伤休克持续了3h复苏的动物模型研究了丹参、维生素E、抗氧化剂协同治疗烧伤休克的作用,效果显著。第5天SOD活性和MDA值均达到伤前水平,提高了动物存活时间。各项生化指标和病理证实,该组实验动物脏器无明显病变,说明联合用药,不仅可以有效的清除氧自由基,还能拮抗脂质过氧化作用,对脏器有较好的保护作用。     

人食管癌组织中热休克蛋白70和糖调节蛋白94的表达

为探讨人食管癌组织中热休克蛋白 70 (HSP70 )和糖调节蛋白 94( grp94)的表达及意义 ,采用SABC法检测人食管癌组织HSP70和grp94的表达 ,镜下观察HSP70和 grp94在癌组织及癌旁组织中的表达特点。结果 :92 .6%( 5 0 /5 4)食管癌组织中存在HSP70的表达 ,癌细胞存在胞质、胞核表达强度及部位的差异 ;而 grp94的表达阳性率为70 .4% ( 3 8/5 4) ,以胞质表达为主 ,而癌旁组织表达较少。提示 :人食管癌组织存在HSP70和 grp94的表达异质性 ,呈现了胞质、胞核的表达差异 ,HSP70和 grp94在人食管癌组织的表达特点为以后肿瘤抗原肽肿瘤疫苗的提取和实验奠定了基础。     

失血性休克复苏及监测指标研究进展

创伤、失血性休克是一古老的临床研究课题。不仅在平时常见，更重要的是与战伤救治密切相关。尽管近10年来取得了一些进展，但复苏时机、复苏目标、液体种类的选择、复苏后继续生命支持以及监测技术等仍是临床以及研究人员面临的重大挑战。本文将就近年来有关上述问题的最新研究进展进行分析和讨论，以期提高对该复杂综合征的认识，为今后的研究提供帮助。     

Spontaneous coronary artery dissection mimicking aortic dissection

A 51-year-old woman suffered rapidly irreversible cardiogenic shock with left hemiparesis. Transesophageal echocardiography, which represents an essential imaging tool in the emergency room, ruled out aortic dissection involving branch vessels but did not allow an in vivo diagnosis of spontaneous coronary dissection. The in vivo diagnosis of spontaneous coronary dissection is rather difficult because of the dramatic clinical presentation and selective coronary angiography requirement.