FGF-21对大鼠血小板聚集和活化的抑制作用

临床上大部分抗血小板药物存在继发性出血等副作用,亟需寻找一种安全有效的抗血小板药物。二磷酸腺苷(ADP)和花生四烯酸(AA)是介导血小板聚集的主要物质,文章探讨成纤维细胞生长因子-21(FGF-21)是否抑制ADP或AA诱导大鼠血小板聚集和活化。将大鼠分为正常对照组、正常鼠血小板活化组、阿司匹林干预后血小板活化组、FGF-21高、中、低剂量干预后血小板活化组。给药干预后提取各组血小板,分别用ADP或AA处理,观察处理后血小板聚集情况以及P选择素和血栓素(TXB2)表达水平。与正常对照组相比,正常鼠血小板经ADP或AA处理活化后,血小板聚集率显著升高,血浆中P选择素和TXB2含量明显上升;与正常鼠血小板经ADP或AA处理活化后相比,经阿司匹林和FGF-21干预后分别经ADP或AA处理活化后的血小板聚集率显著下降,血浆中P选择素和TXB2含量显著下降;FGF-21干预组经ADP或AA活化后,血小板聚集率、P选择素和TXB2含量下降水平呈明显剂量依赖性。目前国内外尚未发现FGF-21对血小板聚集与活化作用的相关报道,研究首次证明FGF-21具有抑制ADP和AA诱导血小板聚集和活化作用及明显的抗血凝作用,填补FGF-21在抗血凝研究领域空白,为开发安全有效的抗血凝药物提供理论依据。     

双花提取物抗血小板聚集及抗凝血活性研究

[目的]研究玫瑰（Rosa rugosa）、月季（Rose chinensis Jacq.）双花提取物对血小板聚集及血液系统的作用。[方法]考察双花提取物对家兔全血凝血时间、体外血小板聚集率、凝血酶原时间（PT）、活化部分凝血活酶时间（APTT）及大鼠纤溶系统的影响;采用高糖诱导人脐静脉内皮细胞损伤模型,考察其对细胞SOD活性和MDA含量的影响。[结果]双花提取物能抑制全血血小板聚集,延长全血凝血时间和APPT,缩短优球蛋白溶解时间（ECLA）,降低纤维蛋白原（FIB）含量。[结论]双花提取物具有抗血小板聚集及抗凝血活性。     

柚皮素单硫酸酯钠盐对血栓形成和血小板聚集的影响

目的 观察柚皮素单硫酸酯钠盐(SNMS)对血栓形成和血小板聚集的影响.方法 将30只SD大鼠随机分为5组:SNMS1组、SNMS2组、血栓通组、肝素组和对照组,每组6只,麻醉大鼠,静脉注射药物后,用血栓生成仪观察大鼠颈动脉血栓形成情况;取兔血与药物孵育5min,凝血酶(500 U/L)作用1 min后,用全血血小板聚集...     

Acetylenic analog of arachidonate that acts like aspirin on platelets

Development of irreversible platelet aggregation and the accompanying release of platelet-bound serotonin and production of prostaglandins is suppressed by 5,8,11,14-eicosatetraynoic acid (TYA). These findings may be explained by an ability of TYA to inhibit the enzymatic conversion of arachidonate to a newly recognized factor, labile aggregation-stimulating substance, which induces platelet aggregation, and to prostaglandins E(2) and F(2alpha).     

Inhibition of platelet aggregation by monoclonal antibody reactive with beta 2-microglobulin chain of HLA complex

A mouse monoclonal antibody that reacts with beta 2-microglobulin, the light chain of class I major histocompatibility antigens, inhibited the second wave of human platelet aggregation induced by adenosine diphosphate and epinephrine and blocked aggregation and platelet protein phosphorylation induced by sodium arachidonate. Thrombin-induced platelet aggregation was inhibited at threshold concentrations but not at higher concentrations. The antibody also inhibited aggregation and secretion in response to thromboxane A2 or the stable endoperoxide analog, U46619. These results suggest that beta 2-microglobulin in the histocompatibility complex is intimately associated with transmission of the endoperoxide-thromboxane signal at the platelet membrane.     

肌醇脂质和cAMP在血小板活化因子诱导血小板聚集中的作用

目的：探讨肌醇脂质和cAMP两个细胞内第二信使系统在血小板活化因子(PAF)诱导血小板聚集过程中所起到的作用和相互关系。方法：采用PKC激动剂PMA和Ca^2 通道A23187,以及PKA激动剂Sp-cAMPS和抑制剂Rp-cAMPS干预的方法,分析观察这两个信使系统在PAF诱导血小板聚集过程中的作用;采用^3H—Inositol和^14C-Adenine双标记液体闪烁技术测定PAF诱导血小板可逆聚集过程中肌醇-1,4,5-三磷酸酯(IP3)和cAMP的水平变化的方法,分析研究这两个信使系统在PAF诱导血小板聚集过程中的相互关系。结果：(1)PMA和A23187能分别增强PAF的血小板聚集效应,而且两者具有协同作用;(2)Rp-cAMP和Sp-cAMPS两者本身都不能引起血小板聚集,但能分别增强和抑制PAF的聚集效应;(3)IP3和cAMP的水平变化分别与血小板的聚集和解聚过程一致。结论：(1)肌醇脂质信使系统是细胞内转导PAF诱导血小板聚集的主要胞内信使系统。(2)降低血小板内cAMP浓度不能诱导聚集,但能增强肌醇脂质信使系统的聚集效应;升高cAMP水平能拮抗肌醇脂质信使系统的作用,这可能是使可逆相聚集的血小板解聚的一个重要机制。     

Thymine dimerization in DNA is an ultrafast photoreaction

Femtosecond time-resolved infrared spectroscopy was used to study the formation of cyclobutane dimers in the all-thymine oligodeoxynucleotide (dT)18 by ultraviolet light at 272 nanometers. The appearance of marker bands in the time-resolved spectra indicates that the dimers are fully formed approximately 1 picosecond after ultraviolet excitation. The ultrafast appearance of this mutagenic photolesion points to an excited-state reaction that is approximately barrierless for bases that are properly oriented at the instant of light absorption. The low quantum yield of this photoreaction is proposed to result from infrequent conformational states in the unexcited polymer, revealing a strong link between conformation before light absorption and photodamage.     

Hemostatic system activity in milk- and plant-fed calves

Experiments were conducted on 36 healthy Simmental and Black Pied calves. Hemostatic indices were determined on days 31, 45, 60, 75, and 90. Maximum increase in platelet aggregation activity was noted on day 45 with the use as inducers ADP + collagen + epinephrine (17.1 s), ADP + thrombin + epinephrine (16.9 s), and ADP + collagen + thrombin + epinephrine (14.1 s). In this case, control of the vessel wall over platelet aggregation in the blood stream increased: the vessel wall antiaggregation activity index (VWAAI) was respectively 1.41, 1.39, and 1.36. An increase in the production by endotheliocytes of antithrombin III and tissue plasminogen activators was revealed in animals at this age. An increase in the level of fibrinogen and factors II, VII, I, X, XI, and XII with stability of factors V and VII and subsequent weakening of activated factors by the end of the examined stage of early ontogeny was established.     

Modulation of alpha-thrombin function by distinct interactions with platelet glycoprotein Ibalpha

Thrombin bound to platelets contributes to stop bleeding and, in pathological conditions, may cause vascular thrombosis. We have determined the structure of platelet glycoprotein Ibalpha (GpIbalpha) bound to thrombin at 2.3 angstrom resolution and defined two sites in GpIbalpha that bind to exosite II and exosite I of two distinct alpha-thrombin molecules, respectively. GpIbalpha occupancy may be sequential, as the site binding to alpha-thrombin exosite I appears to be cryptic in the unoccupied receptor but exposed when a first thrombin molecule is bound through exosite II. These interactions may modulate alpha-thrombin function by mediating GpIbalpha clustering and cleavage of protease-activated receptors, which promote platelet activation, while limiting fibrinogen clotting through blockade of exosite I.     

300Hz脉冲音对许氏平鲉幼鱼的驯化效果

采用300 Hz脉冲波断续音在实验室水槽中对许氏平鲉Sebastes schlegeli幼鱼进行音响驯化试验。结果表明：在驯化第15天开始聚集时间减小到2 s,之后到20 d均无大变化;聚集时间从第5天开始整体呈递减趋势,驯化第16天,聚集时间达到最短（16 s）;聚集率则逐日增加,驯化第18天,聚集率达到最高,为91%,平均聚集率为83.9%;音响驯化结束10 d后再次放声,许氏平鲉开始聚集时间为3 s,聚集时间为44 s,聚集率为86.3%。由此可见,300 Hz脉冲波断续音对许氏平鲉有明显的驯化作用;许氏平鲉对驯化声音记忆力超过10 d且效果显著。     

Uracil photoproducts from uracil irradiated in ice

Two new products were isolated from uracil irradiated with ultraviolet light in frozen aqueous solution. As judged by mass, nuclear magnetic resonance, and ultraviolet and infrared spectra, one is a photopolymer, U(3) and the structure of the other is probably 6-4'-[ pyrimidin-2'-one]-uracil. Formations of these products between pyrimidine bases are apparently common photoreactions, and may be important to the study of the photochemistry and photobiology of nucleic acids.     

Platelet and plasma fibrinogens are identical gene products

Human platelet fibrinogen has been shown to be indistinguishable from plasma fibrinogen by a variety of criteria, including subunit composition and cross-linking characteristics as judged by sodium dodecyl sulfate-gel electro phoresis, quantitative amino terminal analysis of fibrin, and the amino acid compositions of fibrinopeptides released from platelet and plasma fibrinogens is products of the same gene or genes.     

Band gap fluorescence from individual single-walled carbon nanotubes

Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes. We obtained individual nanotubes, each encased in a cylindrical micelle, by ultrasonically agitating an aqueous dispersion of raw single-walled carbon nanotubes in sodium dodecyl sulfate and then centrifuging to remove tube bundles, ropes, and residual catalyst. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions with metallic tubes and substantially broadens the absorption spectra. At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap-selective protonation of the side walls of the tube. This protonation is readily reversed by treatment with base or ultraviolet light.     

不同光质补光对温室葡萄新梢生长的影响

为探讨不同光质补光对温室葡萄生长的影响,以2年生温室盆栽‘京秀’葡萄苗为试材,从展叶开始,每天早晚各补光2 h,以不补光为对照,观测比较红光、蓝光和紫外光(UVA和UVB)处理30 d后的葡萄新梢生长状况。结果表明,不同光质补光处理均促进新梢延长生长,缩短了新梢节间长度。其中,补充红光、蓝光明显增加新梢基部粗度;补充蓝光、紫外光减小了单叶面积;红光处理明显增加了新梢总的干物质积累,而且增大了叶片干物质分配比例。     

Research on Effect of Four Natural Ultraviolet Light Absorbers on Photostabilization of Azadirachtin-A

This study examined the photostabilization of Azadirachtin-A （Aza-A） when exposed to ultraviolet light in the presence of some natural absorbers. Aza-A extract solutions with and without natural UV light absorbers in methanol were applied onto the surface of glass slides. At particular intervals, the remaining concentration of Aza-A was analyzed by HPLC. Using first-order kinetic equation, the dissipation half-life values （DT~0） for the degradation of Aza-A under ultraviolet radiation were obtained. It indicated that the addition of ferulic acid, gallic acid, and rutin provided moderate degree of photostabilization of Aza-A and that addition of aloin provided the best photostabilization of Aza-A, among these UV absorbers studied. Photostabilization of Aza-A by different UV light absorbers appears to be due to the competitive energy absorption of UV photons by the absorbers molecules. The dissipation half-life values of Aza-A after irradiation under ultraviolet light suggested that the addition of aloin （in 1 ： 1 mol ratio） can provide better photostabilization of azadirachtin molecule.     

非线性动态生态系统的完备集结

集结理论是一种研究宏观生态和环境大系统建模和模拟的重要方法。本文中,作者根据生态学中的集结研究成果及自动控制理论,讨论了集结变量和功能的一般原则,以及非线性生态系统建模中完备集结的充要条件;并以若干文献实例支持了作者的结论。     

秋刀鱼集鱼灯箱内不同灯位的照度实验比较研究

通过模拟灯箱光学特性实验,根据集鱼灯灯箱的平面照度分布,利用Matlab 7.0软件建立秋刀鱼集鱼灯照度分布模型,对秋刀鱼集鱼灯灯箱内不同灯位的照明效果进行了研究。结果表明：不同灯位的集鱼灯地面照度随地面距离的增加呈现出先增大后减少的趋势;而灯箱内不同灯位的集鱼灯光强值变化规律与地面照度的变化规律不同,在距离原点1 m时均出现最大值,并且上部灯位光强＞中部灯位光强＞下部灯位光强;随着集鱼灯从上端向下端移动,光强系数k(L)逐渐减小。研究发现,中部灯位光强变化稳定,在一定程度上可以代表整个灯箱的光强变化情况。     

Skin color and nutrient photolysis: an evolutionary hypothesis

Human populations native to areas of intense sunlight tend to be heavily melanized. Previous explanations for this relationship have invoked only weak selective pressures. To test the hypothesis that dark pigmentation may protect against photolysis of crucial light-sensitive vitamins and metabolites by ultraviolet light, folate was used as a model. It was found that exposure of human plasma in vitro to simulated strong sunlight causes 30 to 50 percent loss of folate within 60 minutes. Furthermore, light-skinned patients exposed to ultraviolet light for dermatologic disorders have abnormally low serum folate concentrations, suggesting that photolysis may also occur in vivo. Deficiency of folate, which occurs in many marginally nourished populations, causes severe anemia, fetal wastage, frank infertility, and maternal mortality. Prevention of ultraviolet photolysis of folate and other light sensitive nutrients by dark skin may be sufficient explanation for the maintenance of this characteristic in human groups indigenous to regions of intense solar radiation.     

银与光所产生的协同效应的微生物灭活现象观察

研究发现在使用紫外线(UV-A,395nm)进行照射时,银溶液对微生物的灭活作用得到增强,特别是对真核微生物的灭活作用得到显著增强。为解明这种银与光所产生的协同效应的微生物灭活机理,使用电子自旋共振仪(Electron Spin Resonance,ESR)对溶液进行检测,并采用扫描电子显微镜(SEM)以及测定线粒体酶活性等方法,推测出了其作用机理,即在光照下氧化银(Ag2O)被激活并与水分子发生反应产生羟基自由基(.OH)。羟基自由基破坏真核微生物的细胞壁,失活其细胞内线粒体酶活性,从而引起真核微生物细胞死灭。     

过二硫酸钾氧化降解环境水中O-DDT的研究

[目的]用过二硫酸钾氧化降解环境水中甲氧滴滴涕(O-DDT),为消除O-DDT对环境水的污染提供依据。[方法]以过二硫酸钾为氧化剂,研究了pH值、氧化剂浓度、超声波、紫外光(UV)对过二硫酸钾氧化降解O-DDT的影响。[结果]超声和紫外光的对反应有明显促进作用,6 min时,O-DDT的降解率可以达到99%以上,30 min后没有检测到O-DDT。应用于天然淡水和海水中25 mg/L O-DDT氧化降解时,15 min后没有检测到O-DDT。[结论]该方法降解水中O-DDT简捷、高效。