Identification of the hydroxyl radical and other reactive oxygen species in human neutrophil granulocytes exposed to a fragment of the amyloid beta peptide

A fragment of the amyloid beta protein, βA(25-35), was investigated for its effect on production of reactive oxygen species (ROS) in human neutrophil granulocytes. The formation and identification of ROS were examined by using a 2',7'-dichlorofluorescin (DCF) fluorescence assay, a luminol chemiluminescence assay, electron paramagnetic resonance (EPR) spectroscopy with DEPMPO as a spin trap, and hydroxylation of 4-hydroxybenzoate (4-HBA). The DCF assay showed that βA(25-35) stimulated formation of ROS in a concentration and time dependent manner. The inverted peptide, βA(35-25), gave no response. Also, luminol-amplified chemiluminescence was stimulated by βA(25-35). Incubation with diethyldithiocarbamate (a superoxide dimustase inhibitor) and salicylhydroxamate (SHA; a myeloperoxidase inhibitor) reduced the chemiluminescence. This indicates that hypochlorous acid (HOCl) is formed after exposure to βA(25-35). The EPR spectra indicated a concentration dependent formation of superoxide ( O 2 • - ) - and hydroxyl ( •OH)- radicals. Hydroxylation of 4-HBA to 3,4,-dihydroxybenzoate confirmed production of •OH. This response was attenuated by SHA, indicating involvement of HOCl in formation of •OH. The DCF fluorescence was inhibited with U0126 (an extracellular signal regulated protein kinase (ERK) inhibitor). Further analysis with western blot confirmed phosphorylation of ERK1/2 after exposure to βA(25-35). The phospholipase A 2 (PLA 2 ) inhibitor 7,7-dimethyl-(5Z,8Z)-eicosadienoic acid, and diphenyleneiodonium, which inhibits the NADPH oxidase, also led to a reduction of the DCF fluorescence. The present findings indicate that βA(25-35) stimulates the NADPH oxidase by activating the ERK pathway and PLA 2 . Production of O 2 • - can lead to HOCl and further formation of •OH, which both have a cytotoxic potential.     

The role of oxidative stress in diabetic vascular and neural disease

This review will focus on the impact of hyperglycemia-induced oxidative stress in the development of diabetes-induced vascular and neural dysfunction. Oxidative stress occurs when the balance between the production of oxidation products and the ability of antioxidant mechanisms to neutralize these products is tilted in the favor of the former. The production of reactive oxygen species has been shown to be increased in patients with diabetes. The possible sources for the overproduction of reactive oxygen species is widespread and include enzymatic pathways, autoxidation of glucose and the mitochondria. Increase in oxidative stress has clearly been shown to contribute to the pathology of vascular disease not only in diabetes but also in hypertension, stroke and ischemia. Since the etiology of diabetic neuropathy is considered to have a large vascular component, prevention of oxidative stress in diabetes is considered by many investigators to be a primary defense against the development of diabetic vascular disease. Potential therapies for preventing increased oxidative stress in diabetes and the neural vasculature will be discussed.     

Insecticide resistance in Brazilian Triatoma infestans and Venezuelan Rhodnius prolixus

Resistance levels to insecticides used in control of Chagas Disease vectors were assessed in two species of bugs (Hemiptera: Reduviidae): Triatoma infestans (Klug) from Brazil and Rhodnius prolixus Stål from Venezuela. The resistance ratios, compared to susceptible laboratory strains, were determined by topical application bioassays. The T. infestans PA strain exhibited resistance ratios of 7× to deltamethrin, 3.6× to β‐cyfluthrin and 3.3× to cypermethrin, but was susceptible to β‐cypermethrin and lambda‐cyhalothrin. Rhodnius prolixus CA strain showed resistance to all the pyrethroids evaluated, the resistance ratios ranging between 4.5× to lambda‐cyhalothrin and 12.4× to cypermethrin. Deltamethrin resistance in both strains was decreased by piperonyl butoxide, suggesting oxidative metabolism as cause of resistance.     

In-vitro selection of Vitis vinifera `Chardonnay' with Elsinoe ampelina culture filtrate is accompanied by fungal resistance and enhanced secretion of chitinase

 Proembryogenic masses of grapevine (Vitis vinifera L.) `Chardonnay' (clone 02Ch) were exposed to the culture filtrate of Elsinoe ampelina (deBary) Shear, the causal agent of anthracnose disease. After four or five cycles of recurrent in-vitro selection with medium containing 40% fungal culture filtrate, putative resistant lines RC 1 and RC 2 respectively, were established. The selected lines inhibited the growth of E. ampelina and Fusarium oxysporium (Schlecht.) (isolated from watermelon) in a dual-culture assay and reduced the growth of mycelium on a conditioned-medium test, thus suggesting the involvement of extracellular compounds in resistance. Sodium dodecyl sulfate-polyacrylamide (SDS-PAGE) gel electrophoresis of extracellular proteins from spent suspension-culture medium showed enhanced secretion of new proteins by selected lines. A 36-kDa protein was immunodetected by a chitinase antiserum. This chitinase continued to express constitutively in differentiated somatic embryos and also in the intercellular fluids of plants regenerated from the selected lines. Somatic embryos from selected lines grew uninhibitedly in a medium containing 40% fungal culture filtrate, whereas non-selected (control) somatic embryos became necrotic and died within a few days. Plants regenerated from selected lines exhibited resistance to infection by E. ampelina in both greenhouse tests and detached leaf bioassays. Results suggest that embryogenic cells can be selected for resistance following in-vitro selection, resulting in resistant plants. Whether or not resistant cells pre-existed in the original embryogenic culture or were induced by the selection pressure could not be determined. Received: 12 November 1999 / Accepted: 3 December 1999     

Inter-simple-sequence-repeat (ISSR) polymorphisms are useful for finding markers associated with disease resistance gene clusters

 We describe a simple and new approach, based on inter-simple sequence repeats (ISSRs), for finding markers linked to clusters of disease resistance genes. In this approach, simple sequence repeats (SSR) are used directly in PCR reactions, and markers found to be linked to disease resistance genes provide important information for the selection of other sequences which can be used with PCR to find other linked markers. Based on an ISSR marker linked to a gene of interest, many new markers can be identified in the same region. We previously demonstrated that ISSR markers are useful in gene tagging and identified a marker, UBC-855₅₀₀, linked to the gene for resistance to fusarium wilt race 4 in chickpea. This ISSR marker provided the information used in the present study for selecting other primers which amplified a region linked to the gene for resistance to fusarium wilt race 4. The primers were based on homology with the (AC)_n sequence and were used for PCR amplifications. Changes in the sequence were at the anchor region of the primers. The repeat (AC)₈T amplified a marker, UBC-825₁₂₀₀, which was located 5.0 cM from the gene for resistance to fusarium wilt race 4 and was closer than other markers. These results indicated that ISSR markers can provide important information for the design of other primers and that by making changes at the 3′ and 5′ anchors close linkage to the desired gene can be found. The approach allows rapid scanning of the targeted region and may provide important information for genome analysis of plant species. Received: 20 January 1998 / Accepted: 19 March 1998     

崔尚志中西医结合生平及思想

崔尚志（1924—1989）,辽宁名医,中西医结合的开拓者,活血化瘀研究的先驱者,毕生从事中西医结合防治冠心病的临床与研究。他参与研制了“冠心1号”等制剂,通过临床系列研究,总结其疗效规律,并率先开展动物实验研究,探讨中药制剂防治冠心病的作用机制。他主张中医“辨病”“辨证”与西医“辨病”相结合的方法辨证论治,以《内经》理论指导冠心病治疗,将冠心病辨为“心痹”病,分别气滞血瘀、气虚血瘀两大主证,并根据冠心病临床合并症不同,再分为阴虚阳亢等八个兼证。     

结直肠离子通道与先天性巨结肠关系的研究进展

离子通道是细胞膜上一类特殊亲水性蛋白微孔道,也是肌肉、神经细胞等电活动的物质基础。目前研究通过生物学及离子通道膜片钳等新技术对离子通道有了进一步的认识,并逐步发掘离子通道的结构功能异常与疾病的发生存在的紧密关系。先天性巨结肠症(Hirschsprung's Disease,HD)又称无神经节细胞症,是小儿外科的常见疾病之一。HD临床表现为胎粪排出延迟、顽固性便秘及腹胀,常并发小肠结肠炎、低位肠梗阻等。目前研究尚未完全明确HD的发病机制,本文对HD的发生与结直肠离子通道功能间的关系作一综述。     

肌钙蛋白I水平检测对急诊房颤患者的临床意义

目的:探讨房颤患者急诊入院时检测肌钙蛋白I(Tn I)水平的临床作用及预测价值。方法:回顾性分析我院523例房颤患者的临床资料,将资料中数据进行统计学分析处理。患者分为三组:1组患者Tn I轻度升高;2组患者Tn I正常;3组患者未检测Tn I,分别就三组患者的基线特征以及就诊时的症状展开数据比较,并且单变量及多变量分析Tn I升高的预测因子。设置主要终点为1年内所有原因导致的死亡及心肌梗死(MI),患者从入院时起随访1年,记录期间的MI发生情况及死亡情况。结果:173例患者(33%)Tn I轻度升高(均值0.56 ng/m L),225例患者(43%)Tn I正常,125例患者(24%)未检测Tn I。住院期间1组患者(50%)的心功能检查异常明显高于组2和组3(28%和29%,P≤0.001),1组患者(22%)主要终点发生率明显高于2组(10%)和3组患者(15%)(P=0.002),有统计学意义。结论:肌钙蛋白I轻度升高与冠脉疾病(CAD)发生率增加及MI发生率增加有关,但对于总体死亡率无影响。