Reactive oxygen species and human spermatozoa: physiology and pathology

The role of reactive oxygen species (ROS) in the pathophysiology of human sperm function has been emphasized in recent years. ROS production in semen has been associated with loss of sperm motility, decreased capacity for sperm–oocyte fusion and loss of fertility. There is a current presumption that the most prolific source of ROS in sperm suspensions is an NADPH oxidase located in leukocytes or in spermatozoa which produces superoxide which is further converted to peroxide by the action of superoxide dismutase. Hydrogen peroxide has been recognized as the most toxic oxidizing species for human spermatozoa, which are very sensitive to lipid peroxidation owing to the high content of polyunsaturated fatty acids in their plasma membrane, though this is not the sole mechanism by which sperm function might be impaired by ROS. Although the excessive production of ROS is detrimental to human spermatozoa, there is a growing body of evidence which suggests that ROS are also involved in the physiological control of some sperm functions. This review focuses on the nature and source of the ROS generated by human spermataozoa as well as their operational mechanisms and their effects, which may be detrimental or beneficial.     

Effect of defective connective tissue on the formation of aneurysmal-like structures in the rat testicular artery

Microscopic aneurysmal-like structures (ALS) develop spontaneously in the convoluted rat testicular artery and have been previously proposed as a model relevant to cerebral aneurysms. The effect of defects in connective tissue fibres on ALS formation was investigated by microscopy using two approaches: (i) the study of the effect of β-aminopropionitrile (BAPN), an inhibitor of the cross-linking of elastic and collagen fibres, on the incidence, size and morphology of ALS in spontaneously hypertensive rats (SHR) and their normotensive controls (WKY). The straight spermatic artery was studied for comparison. (ii) The determination of the incidence of spontaneous ALS in Brown Norway (BN) and Long Evans (LE) rats which are highly susceptible (BN) or resistant (LE) to the spontaneous rupture of the arterial internal elastic lamina. (i) BAPN increased the number and size of ALS in SHR and WKY rats and had no effect on the straight spermatic artery and (ii) ALS were more numerous and of greater size in BN than in LE rats. Taken together, these results show that defective connective tissue fibres may favour the formation and induce the enlargement of aneurysmal-like structures. By analogy, these data suggest that a lack of connective tissue fibre integrity may be of importance in cerebral aneurysm formation and development.     

Effects of fenflumizole on aggregation ex vivo of human platelets and formation of thromboxane B2 and 6-keto-prostaglandin-F_{1\alpha }

Summary Fenflumizole (2-(2,4-difluorophenyl)-4,5-bis(4-methoxyphenyl)imidazole), a new non-steroidal anti-inflammatory drug, was given to healthy subjects in single oral doses of 0.1, 1 and 2 mg/kg. The effect of the drug was followed for up to 8 h by repeated tests of arachidonic acid-induced platelet aggregation and was related to its concomitant plasma concentration. Fenflumizole reversibly inhibited platelet aggregation and the degree of inhibition was found to be linearly correlated with the log plasma concentration. There was depression of the formation of thromboxane B₂ and 6-keto-prostaglandin F₁ (the stable metabolites of thromboxane A₂ and prostacyclin) in clotted whole blood measured by radioimmunoassay after fenflumizole 1 mg/kg. This effect was directly related to the concentration of the drug in plasma, the maximum effect being reached at fenflumizole concentrations >200 ng/ml. EC₅₀-values for inhibition of the formation of thromboxane B₂ and 6-keto-prostaglandin were approximately 20 and 40 ng/ml, respectively. The results suggest that orally administered fenflumizole is a potent inhibitor of platelet aggregation and prostanoid formation.     

投影遗传算法

针对一般遗传算法在求解优化问题的多个优化解时的局限性,结合曲面投影与遗传算法的基本思想,提出了一种基于曲面投影的投影遗传算法用于解决此类问题,数值验证的结果表明了本算法的有效性和实用性。     

胰腺癌侵犯胰周结构的CT评价

目的探讨胰腺癌的CT诊断价值.方法对76例胰腺癌的CT表现进行分析并与手术病理结果对照.结果①胰腺癌在CT上表现为低密度的肿块,不强化或强化不明显,肿块边缘不规则强化;②胰头癌可引起胆总管、胰管的扩张;③胰腺癌多伴邻近血管及脏器受侵.结论 CT能正确评价胰腺癌及胰周浸润,是判断胰腺癌能否手术切除的重要检查手段.