Epidemiological characteristics of platelet aggregability.

The epidemiological characteristics of platelet aggregability were established in 958 participants in the Northwick Park Heart Study. The main analyses were based on the dose of adenosine diphosphate at which primary aggregation occurred at half its maximum velocity. Aggregability increased with age in both sexes, was greater in whites than blacks (particularly among men), and tended to decrease with the level of habitual alcohol consumption. Aggregability was, however, greater in women than men and in nonsmokers than smokers. There was no relation between aggregability on the one hand and obesity, current or past oral contraceptive use, menopausal state, or blood cholesterol and triglyceride concentrations on the other. Aggregability was somewhat, though not significantly, higher in men with a history of ischaemic heart disease and in those with electrocardiographic evidence of ischaemia than in those without. There was a strong association between the plasma fibrinogen concentration and aggregability. The widely held concept of platelet aggregability and its implications is probably an oversimplification. In the prevention of thrombosis it may be as useful to consider modifying external influences on platelet behaviour, such as plasma fibrinogen concentration or thrombin production, as it is to rely solely on platelet active agents.     

抗冻蛋白特征、作用机理与预测新进展

抗冻蛋白（antifreezeproteins,AFPs）可以通过抑制冰晶生长保护生物体免受低温冻害,具有重要的生物学意义和应用价值。现在在鱼类、节肢动物、植物及微生物中均发现有AFPs的存在。基于对已有研究文献和相关网络数据的系统调查统计,详细描述了AFPs数据的类别特征,并对其作用机理的研究历史和最新取得的突破性进展作了较为系统的阐述,并对AFPs预测所取得的成果作了介绍,还对AFPs研究的现状和未来研究方向作了讨论和展望。     

候鸟迁徙过程中"雄性早现"的六种假说及未来研究热点

"雄性早现"(protandry)是指雄性相对于雌性更早进入繁殖状态或更早到达繁殖地的现象.该文针对候鸟的雄性比雌性在春季时更早到达繁殖地这一现象,介绍了雄性早现的6种假说,即等级优势(rank advantage)假说、敏感性(susceptibility)假说、限制性(constraint)假说、交配机会(mate opportunity)假说、等待代价(waiting cost)假说和配偶选择(mate choice)假说,并通过近年来的研究证据阐述了上述假说对解释候鸟雄性早现的适用性.此外,对鸟类雄性早现未来研究中可能的热点问题做了展望.     

大鼠去神经支配脾脏内淋巴细胞ERK表达变化的研究

目的:探讨脾脏神经支配与免疫功能关系.方法:清洁级成年雄性SD大鼠20只,随机分成实验组、对照组.手术切除实验组10只大鼠脾脏神经纤维,饲养1周后取出脾脏,4%多聚甲醛固定,石蜡切片行HE染色及ABC免疫组织化学染色.结果:(1)HE染色两组大鼠脾脏结构结构清晰,动脉周围淋巴鞘内淋巴细胞密集成团状,红髓内可见大量红细胞,在去除大鼠脾脏神经支配的实验组较对照组脾脏大体结构无明显变化;(2)两组脾脏淋巴细胞均有ERK表达,对照组正常脾脏表达ERK阳性细胞占16.2%,实验组仅占6.0%.实验组脾脏内表达ERK阳性细胞数量明显低于对照组,差异具有显著性(P＜0.01),同时ERK表达量也低于对照组,且差异具有显著性(P＜0.01).结论:在去除神经支配后,脾脏内淋巴细胞增殖活性明显降低,在一定程度上影响到脾脏免疫功能.     

低密度脂蛋白胆固醇升高在家兔动脉粥样硬化发生发展中的意义

目的观察低密度脂蛋白胆固醇(LDL-c)对家兔动脉粥样硬化(AS)形成的影响,探讨AS的发生机制。方法以高脂饲料复制家兔实验性AS模型,分阶段检测家兔血清胆固醇(TC)、甘油三脂(TG)、高密度脂蛋白胆固醇(HDL-c)和低密度脂蛋白胆固醇(LDL-c)含量;观察主动脉内膜病理学变化;分析主动脉内膜增生程度及AS斑块面积与血浆脂蛋白水平的相关性。结果高脂组家兔主动脉粥样硬化面积和内膜增生程度明显较对照组增加(P<0.01),血浆LDL-c水平明显较对照组升高(P<0.01);动脉内膜增生程度及AS斑块面积均与血浆LDL-c水平呈非常显著正相关(r=0.837,P<0.001)。结论提示血浆LDL-c水平升高,是致AS发生发展的重要原因。     

ADP-ribosyltransferase activity during the friend virus-induced murine erythroleukemia cell differentiation

A variety of chemical agents that are known to induce erythrodifferentiation in the Friend virus-induced murine erythroleukemia (MEL) cell have been suggested to mediate DNA cleavage in cultured cells prior to differentiation. The activation of the nuclear enzyme, ADP-ribosyltransferase, depends upon the presence of single strand breaks in DNA. If dimethyl sulfoxide (Me2SO) causes DNA breakage, it would be expected that the activity of ADP-ribosyltransferase would increase. A study of ADP-ribosyltransferase activity during cell growth indicates that both Me2SO-treated and untreated MEL cells exhibit a similar increase in the enzyme activity but the increase in Me2SO-treated cells is delayed by a few hours. When examined at comparable stages of growth, both treated and untreated cells show almost identical levels of enzyme activity. The present data thus do not support the contention that Me2SO induces DNA breakage in the MEL cells.     

Effects of microtubule-inhibitors on nuclear migration and rhizoid differentiation in germinating fern spores (Onoclea sensibilis)

Summary Germinating spores of the sensitive fern,Onoclea sensibilis L., undergo premitotic nuclear migration before a highly asymmetric cell division partitions each spore into a large protonemal cell and a small rhizoid initial. Nuclear movement and subsequent rhizoid formation were inhibited by the microtubule (MT) inhibitors, colchicine, isopropyl-N-3-chlorophenyl carbamate (CIPC) and griseofulvin. Colchicine prevented polar nuclear movement and cell division so that spores developed into enlarged, uninucleate single cells. CIPC and griseofulvin prevented nuclear migration, but not cell division, so that spores divided into daughter cells of approximately equal size. In colchicine-treated spores, MT were not observed at any time during germination. CIPC prevented MT formation at a time coincident with nuclear movement in the control and caused a disorientation of the spindle MT. Both colchicine and CIPC appeared to act at a time prior to the onset of normal nuclear movement. The effects of colchicine were reversible but those of CIPC were not. Cytochalasin b had no effect upon nuclear movement or rhizoid differentiation. These results suggests that MT mediate nuclear movement and that a highly asymmetric cell division is essential for rhizoid differentiation.     

THE PHYSIOLOGICAL EFFECTS OF l-TYROSINE AND l-PHENYL-ALANINE ON THE RATE AND QUALITY OF PULSATION IN THE SEVENTY-TWO HOUR EXTIRPATED EMBRYONIC CHICK HEART

1. 72 hour isolated chick hearts show an increase in pulsation rate when placed in M/1000, M/10,000, and M/50,000 l-tyrosine solutions. The optimal effect is seen in M/10,000 and M/50,000 l-tyrosine. 2. All hearts show disturbance of rhythm either in the form of irregular rhythm or heart block. 3. 62 hour isolated chick hearts are not susceptible to l-tyrosine while 96 hour hearts are markedly sensitive. 4. 72 hour isolated chick hearts placed in 1 part in 10,000 and 1 part in 50,000 l-epinephrine show approximately the same effects as were seen with l-tyrosine. 5. 72 hour isolated chick hearts placed in M/1000 and M/10,000 l-phenylalanine show an initial depression followed by an l-tyrosine effect.