Effects of cefonicid on platelet aggregation

Beta-lactam antibiotics may interfere with platelet aggregation by inhibiting the binding of agonists of platelet aggregation, such as ADP and collagen, to specific receptor sites. The aim of this study was to evaluate in vitro the effects of cefonicid, a semi-synthetic cephalosporin, on platelet aggregation. Spontaneous platelet aggregation and platelet aggregation induced by ADP and collagen were assessed. Platelets from healthy subjects were incubated with cefonicid at final concentrations of 0.1 mg/ml, 1 mg/ml and 10 mg/ml (0.1 mg/ml is the concentration of cefonicid achieved in humans at therapeutic doses). When compared with saline, cefonicid at a concentration of 0.1 mg/ml had no effect on platelet aggregation, but at 1 mg/ml it inhibited ADP-induced aggregation and at 10 mg/ml it also inhibited aggregation induced by collagen. These findings suggest that therapeutic doses of cefonicid do not affect platelet aggregation.     

The mechanism of anti-platelet activity of davallialactone: involvement of intracellular calcium ions, extracellular signal-regulated kinase 2 and p38 mitogen-activated protein kinase

This study was designed to investigate the effect of davallialactone, which was isolated from the mushroom Inonotus xeranticus, on platelet aggregation induced by collagen, thrombin and ADP. We found that davallialactone dose-dependently inhibited platelet aggregation that was stimulated either by collagen (2.5 microg/ml), a potent ligand of integrin alpha2beta1 and glycoprotein VI, or by thrombin (0.1U/ml), a potent agonist of the protease-activated receptors (PARs) PAR1 and PAR3. In addition, davallialactone inhibited platelet aggregation induced by ADP, an agonist of P2Y receptor. To understand the mechanism of anti-platelet activity, we determined whether davallialactone affected the downstream signaling in collagen-activated platelets. Using the fura-2/AM fluorometric assay, we found that davallialactone dose-dependently inhibited intracellular calcium concentration levels ([Ca2+]i). Moreover, davallialactone inhibited the phosphorylation of extracellular signal-regulated protein kinase (ERK)-2 and p38 mitogen-activated protein kinase (MAPK), in a dose-dependent manner. The tyrosine phosphorylation of 60 and 85kDa proteins, which were activated by collagen, were differentially inhibited by davallialactone. Taken together, these data suggest that davallialactone may have potential anti-platelet aggregation activity via suppression of intracellular downstream signaling pathways.     

The effect of Trimeresurus mucrosquamatus snake venom on platelet aggregation

Trimeresurus mucrosquamatus venom decreased the platelet number in rabbits to about 10–20% of the control after i.v. injection (1 mg. kg body weight). The venom induced platelet aggregation of rabbit platelet-rich plasma and washed platelets at concentrations between 1 and 1000 μg/ml, with the maximum at 30 μg/ml. Venom-induced platelet aggregation was calcium dependent and was accompanied by release of nucleotides. This aggregation was potentiated by potassium cyanide, and inhibited by N-ethylmaleimide. The venom also induced aggregation of ADP-refractory platelets.     

Effect of the purified phospholipases A2 from snake and bee venoms on rabbit platelet function

Effects of seven purified phospholipases A2 from the venoms of snakes (Naja naja atra, Trimeresurus mucrosquamatus and T. gramineus) and honey bee (Apis mellifera) on rabbit washed platelet suspension in the absence of bovine serum albumin have been studied. Only phospholipases A2 from N. n. atra, T. mucrosquamatus and A. mellifera venoms induced platelet aggregation with small amounts of 14C-serotonin release. They showed tachyphylaxis and also cross-tachyphylaxis in inducing platelet aggregation. The former two phospholipases A2 exhibited biphasic responses in which irreversible aggregations appeared at concentrations of 1-10 micrograms/ml. At higher concentrations, they elicited the reversible aggregation. Exogenous Ca2+ was essential to their activity. Indomethacin and EDTA completely abolished both phospholipase A2 induced platelet shape change and aggregation, while mepacrine, prostaglandin E1, verapamil and nitroprusside inhibited only the aggregation response. p-Bromophenacyl bromide-modified phospholipases A2, which almost completely lost enzymatic activity, failed to induce platelet aggregation. Phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol inhibited the phospholipase A2-induced platelet aggregation. These phospholipases A2 induced thromboxane B2 formation which was inhibited by EDTA and indomethacin, but not by prostaglandin E1. Pre-treatment of platelet suspension with phospholipase A2 from N. n. atra or A. mellifera venom (50 micrograms/ml) inhibited platelet aggregation induced by sodium arachidonate or collagen, but not that induced by thrombin or ionophore A-23187. Exogenous sodium arachidonate or lysophosphatidylcholine also showed unaltered inhibitory spectrum on platelet aggregation. It is concluded that phospholipases A2 induce platelet aggregation by virtue of their enzymatic activity, cleaving the membrane phospholipids resulting in arachidonic acid release and formation of thromboxane A2. On the other hand, the cleaved products, lysophosphatidylcholine, arachidonic acid or arachidonate metabolites (via lipoxygenase pathway) may be responsible for anti-platelet activity.     

注射用羟基红花黄色素A对家兔血小板聚集、超微结构及血小板活化因子诱导后富血小板血浆中GMP-140含量的影响

目的:观察注射用羟基红花黄色素A(HSYA)对家兔血小板聚集功能及超微结构的影响。方法:采用体内实验法,观察3种剂量的注射用HSYA(10、5和2.5mg/kg)对由花生四烯酸(AA)、二磷酸腺苷(ADP)和血小板活化因子(PAF)(3.6nmol/L)诱导的家兔血小板聚集作用的影响,以及血小板超微结构的变化;并单独研究了以PAF为诱导剂的情况下,富血小板血浆(PRP)中α-颗粒膜蛋白-140(GMP-140)的含量。结果:各剂量HSYA注射剂能抑制AA、PAF诱导的家兔血小板聚集(P<0.05,P<0.01);扫描电镜显示:各剂量HSYA注射剂能减少AA和PAF诱导后的聚集型血小板数量并使树突型血小板突起变少变短(P<0.05,P<0.01);另外,各剂量HSYA注射剂还能降低经PAF诱导后GMP-140的含量(P<0.01)。结论:注射用羟基红花黄色素A具有显著的抗PAF诱导的血小板聚集作用,抑制血小板的活化,从而为临床抗血小板聚集药物的使用提供更多选择。     

Triflavin potentiates the antiplatelet activity of platelet activating factor receptor antagonist on activated neutrophil-induced platelet aggregation

In this study, specific platelet activating factor (PAF) receptor antagonist ginkgolide B (BN52021) was tested for its antiplatelet activity in zymosan activated polymorphonuclear neutrophil-induced platelet aggregation. Triflavin was also tested for its antiplatelet activity compared with PAF receptor antagonist. Triflavin, an Arg–Gly–Asp-containing disintegrin purified from venom peptide inhibited platelet aggregation by interfering with the interaction of fibrinogen with the glycoprotein IIb/IIIa complex. Furthermore, we also report an efficient high resolution method for quantitative analysis of PAF using high-performance capillary electrophoresis (HPCE). The supernatant of polymorphonuclear neutrophils after their activation by opsonized zymosan induces the aggregation of washed rabbit platelets. In rabbit platelets, BN52021 (100–1000 μM) only partially inhibited activated polymorphonuclear neutrophil-induced platelet aggregation, and its maximal inhibition was estimated to be about 79%. Triflavin also partially inhibited platelet aggregation about 82% induced by activated polymorphonuclear neutrophils. Furthermore, after treatment with a combination of triflavin (0.26 μM) with various concentrations of BN52021 (4–1000 μM), the inhibitory effect of platelet aggregation was almost completely. This inhibition was greater than that produced by the individual drugs alone. These results indicate that a combination of glycoprotein IIb/IIIa complex and PAF receptor antagonist could completely inhibit activated polymorphonuclear neutrophil-induced platelet aggregation. In addition, the amount of PAF released from zymosan (6 mg/ml)-activated polymorphonuclear neutrophils was accurately calculated about 11.8±1.5 ng/10⁶ cells, and did not further increase even at a high concentration of zymosan (10 mg/ml). These results suggest that PAF play a major role in the interaction between platelets and polymorphonuclear neutrophils. This interaction may be important in the pathogenesis of thrombosis and inflammatory diseases. Our present findings support the hypothesis that combination therapy with glycoprotein IIb/IIIa complex antagonists and PAF receptor antagonists may represent a new approach to the treatment of ischemic disorders.     

人参皂甙对血小板聚集性、cAMP和cGMP含量的影响

本文报告了人参皂甙对家兔血小板聚集性,cAMP和cGMP含量的影响。结果表明,人参皂甙在体内外均抑制由花生四烯酸、ADP和凝血酶诱导的血小板聚集。同时,人参皂甙明显升高血小板中cAMP含量,但是不影响血小板中cGMP含量。提示人参皂甙对血小板聚集的抑制作用与其升高血小板中cAMP含量有关。     

绞股蓝总皂甙对家兔血小板聚集释放及cAMP水平的影响

本文研究了绞股蓝总皂甙对家兔血小板聚集、5—羟色胺释放及血小板内cAMP含量的影响.结果发现绞股蓝总皂甙在体内和体外均明显抑制二磷酸腺苷,花生四烯酸和胶原诱导的血小聚集;抑制血小板5—羟色胺的释放;升高血小板内cAMP的水平.效应与剂量间呈现依赖关系.提示绞股蓝总皂甙为一血小板功能抑制剂,作用机理可能与其升高血小板内cAMP的水平,抑制血小板释放活性物质有关.     

当归及其成分阿魏酸对大鼠血小板聚集和5-HT释放的影响

本文报告当归及其成分阿魏酸对大鼠血小板聚集性和5-HT释放反应的影响。结果表明,当归水剂在试管内当浓度为200～500mg/ml,阿魏酸0.4～0.6mg/ml时抑制ADP和胶原诱导的大鼠血小板聚集。静脉注射当归20g/kg 5分钟后对ADP和胶原诱导的大鼠血小板聚集有明显的抑制作用。阿魏酸钠0.2g/kg和0.1g/kg静脉注射时分别抑制ADP和胶原诱导的大鼠血小板聚集。用³H-5HT标记血小板,观察血小板聚集和释放反应的关系。当归水剂500mg/ml和阿魏酸钠1～2mg/ml对凝血酶诱导的血小板聚集有明显抑制作用,同时也抑制³H-5HT从血小板中释放。     

香草酸抗血小板聚集作用的体内外研究

目的香草酸是一种酚酸类化合物,具有抗氧化、抗炎等药理作用,其抗血栓作用尚未有报道。本实验室前期通过筛选发现香草酸具有良好的抗血小板聚集作用,因此本研究通过体内外实验对香草酸抗血小板聚集的作用进行系统评价。方法采用花生四烯酸(arachidonic acid,AA)、二磷酸腺苷(adenosine diphosphate,ADP)、凝血酶(thrombin,THR)诱导体内外血小板聚集模型,结合凝血四项检测评价香草酸抗血小板聚集及抗血栓的作用。结果体外实验中,香草酸对ADP和AA诱导的血小板聚集具有显著抑制作用,并剂量依赖性抑制ADP诱导的血小板聚集;体内试验中,香草酸(10、30和100 mg/kg)能够剂量依赖性抑制ADP和AA诱导的血小板聚集;同时,香草酸(100 mg/kg)能显著降低纤维蛋白原、增加凝血酶原时间,对活化部分凝血活酶时间和血浆凝血酶时间无明显影响。结论本研究首次发现香草酸对ADP和AA诱导的血小板聚集具有抑制作用,为研发具有自主知识产权的抗血小板聚集药物提供了实验依据。     

Inhibition of platelet aggregation by polyaspartoyl L-arginine and its mechanism

AIM: To observe the oral anti-platelet efficacy and the potential action mechanism of polyaspartoyl L-arginine (PDR), a new L-arginine rich compound. METHODS: Platelet aggregation was conducted by Born's method; bleeding time was determined using tail's bleeding time in mice; platelet adhesion was carried out with glass bottle method; nitric oxide (NO) was tested with Griess's method; and cAMP, thromboxane B(2) (TXB(2)) and 6-keto-PGF(1 alpha ) were assessed with commercial kits. RESULTS: The inhibition by PDR (15-60 mg/kg i.g. or 10 mg/kg i.v.) of platelet aggregation induced by adenosine diphosphate (ADP), collagen or thrombin at 1 h after oral administration or at 20 min after i.v. injection for rats (P<0.01), and its (15 mg/kg, i.g.) inhibition of ADP-induced platelet aggregation for rabbits during 6 h after administration were observed. PDR (15-60 mg/kg) prolonged the bleeding time of mice (P<0.05) and (30 mg/kg) increased NO concentration in plasma. On the other hand PDR did not change the contents of cAMP in platelet and TXB2 or 6-keto-PGF(1 alpha) in plasma. CONCLUSION: PDR is a novel, oral effective platelet aggregation inhibitor and its action mechanism possibly related to increasing NO generation.     

Plasma acid-base and electrolyte states of rainbow trout exposed to alum (aluminum sulphate) in acidic and alkaline environments

The effects of alum (aluminum sulphate) on the ability of rainbow trout to regulate their plasma acid-base and electrolyte states were investigated in the face of acidic and alkaline shifts in water pH. At water pH 4.3, alum exacerbated plasma acid-base and electrolyte disturbances and decreased fish survival, in a concentration-dependent manner. The threshold for no acute effect was below 0.5 mg/l (0.05 mg/l Al). At water pH 7.8, alum to 10 mg/l (0.91 mg/l Al) had no detectable effect on plasma characteristics or fish survival. At water pH 8.7, alum concentrations ≤1 mg/l (0.09 mg/l Al) ameliorated plasma acid-base and electrolyte disturbances and increased fish survival, relative to the effects observed without alum. Thus at pH 8.7, low concentrations of alum protected the fish from the effects of base exposure. Alum concentrations ≥10 mg/l (0.91 mg/l Al) at pH 8.7 exacerbated plasma electrolyte disturbances and reduced fish survival. These results are probably reflective of the toxic effects of Al(OH)₄⁻. The threshold for no acutely toxic effect of Al(OH)₄⁻ appeared to lie between 0.45 and 0.91 mg/l Al.     

山茱萸环烯醚萜苷对家兔、大鼠血小板聚集及出血时间的影响

目的：研究山茱萸环烯醚萜苷（CIG）对血小板聚集和出血时间的影响。方法：应用比浊法测定家兔（体外实验）及血瘀模型大鼠（体内实验）的血小板聚集率;断尾法观察大鼠出血时间。采用肾上腺素加冰水刺激法制备血瘀大鼠模型。结果：在体外实验中,CIG（0.75～3 mg/mL）能明显抑制二磷酸腺苷（ADP）或花生四烯酸（AA）诱导的家兔血小板聚集（P〈0.05,P〈0.01）,对血小板活化因子（PAF）诱导的血小板聚集无显著影响,但更大剂量（6～12 mg/mL）能抑制PAF诱导的血小板聚集（P〈0.01）。在体内实验中,CIG大剂量（180 mg/kg）灌胃给药能显著抑制ADP诱导的血瘀模型大鼠血小板聚集（P〈0.01）,延长正常大鼠的出血时间（P〈0.05）。结论：山茱萸环烯醚萜苷具有抗血小板聚集作用,大剂量能够延长出血时间。     

In vitro investigation on the antiaggregating activity of ditazole

The antiaggregating activity of ditazole, a non-steroidal antiinflammatory drug, was assayed in vitro on platelets from 16 subjects at high risk of thrombosis and from 14 healthy control subjects. This study was performed by the photometric method (Born) on platelet rich plasma (PRP), preincubated with ditazole at final concentrations of 1, 2.5, 4 and 40 micrograms/ml. Aggregation was induced by 1 and 2 microM ADP, 1 and 10 microM adrenaline and by 1 and 2 mM arachidonic acid (AA). Ditazole (1 microgram/ml) inhibited platelet aggregation induced by ADP (1 and 2 microM) in both groups and significantly reduced at all concentrations tested adrenaline (10 microM) induced aggregation in subjects at risk, but only at 2.5 micrograms/ml concentration in control subjects. Arachidonic acid (1 mM)-induced aggregation was significantly reduced by ditazole at all concentrations tested in control subjects but only at 2.5 micrograms/ml or more in subjects at risk. In both groups, however, aggregation induced by 2 mM AA was significantly reduced by ditazole at all concentrations tested.     

Anti-thrombotic effects of higenamine

The anti-platelet and anti-thrombotic effects of higenamine, a benzyltetrahydroisoquinoline alkaloid of the roots of Aconitum japonicum (Ranunculaceae), were investigated. The degree of platelet aggregation was measured with platelet rich plasma (PRP). An acute thrombotic condition was induced in mice by the injection of the mixture of collagen and epinephrine. The thrombus formation was induced inside the arterio-venous shunt tube installed between an abdominal aorta and the renal vein of rats. Higenamine showed inhibitory activities to both human and rat platelet aggregation induced by ADP, collagen and epinephrine. It was more inhibitory to epinephrine induced aggregation (IC(50); 19 and 7.2 microM to human and rat platelets respectively) than ADP- or collagen-induced aggregation. The anti-thrombotic effects of higenamine were also observed in both mouse acute thrombosis model and rat arterio-venous shunt (AV-shunt) models. The oral administration of higenamine (50 or 100 mg/kg) increased the recovery rates from the acute thrombotic challenge in mice and lowered the weight of thrombus formed inside the AV-shunt tube in rats.     

复方丹参滴丸干预氯吡格雷抵抗的临床研究

目的探讨复方丹参滴丸对氯比格雷抵抗患者的干预效果。方法采用比浊法测定血小板聚集率,将氯比格雷抵抗患者58例随机分为两组,氯比格雷＋复方丹参滴丸组及单服氯吡格雷组,每组29例。干预2周后分别复查血小板聚集率。结果干预后氯吡格雷＋复方丹参滴丸组二磷酸腺苷（ADP）诱导的血小板聚集率为28．25％,较干预前的37．78％下降9．53％（P〈0．01）;而单用氯吡格雷组干预前后无明显变化（P〉0．05）。结论复方丹参滴丸可以增强患者对氯比格雷的敏感性,减轻氯比格雷抵抗,两药有协同抗血小板作用。     

Inhibition of human and rabbit platelet aggregation by chlorophenoxyacid herbicides

Inhibition of human platelet aggregation by eight chlorophenoxyacid herbicides was studied in vitro. Thrombocyte aggregation in the platelet-rich plasma was induced by 1.0–32.0 M adenosine diphosphate (ADP), 0.32–32.0 M adrenaline or 7.5–30.0 g/ml collagen with and without chlorophenoxyacid (0.05–2.0 mg/ml). Platelet aggregation by each inducer was inhibited dose dependently by all the eight chlorophenoxyacids at concentrations between 0.1 and 2.0 mg/ml. Increasing the concentrations of ADP and collagen but not of adrenaline inhibited the antiaggregatory action of chlorophenoxy-acids. No essential differences in inhibitory effect were found between different chlorophenoxyacids varying in respect of their ring substituents and the length of the carboxylic side chain. In the platelet-rich plasma prepared from rabbits 2.5 h after subcutaneous injection of 2,4-dichlorophenoxyacetic acid or 4-chloro-2-methylphenoxy-acetic acid (100–150 mg/kg), platelet aggregation by ADP was inhibited 20–30%, compared to plasma taken from the rabbits before the chlorophenoxyacid treatment. The inhibition had disappeared by 20–23 h after administration. The results indicate that chlorophenoxyacid herbicides inhibit human platelet aggregation. Furthermore, the inhibition is probably involved in haemorrhages known to occur in various tissues of animals intoxicated by chlorophenoxyacid herbicides.     

Compared effects of the two antiinflammatory drugs indoprofen and lonazolac on thromboxane generation and on platelet aggregation, related to plasma concentrations after single oral doses

Single doses of indoprofen 100 mg and lonazolac-Ca 200 mg were given orally to eight healthy volunteers. Blood samples were taken prior to and at various times until 24 hours after the dose. Drug concentrations in plasma were analyzed by HPLC and thromboxane B2 (TXB2) in serum by radioimmunoassay. Platelet aggregation in plasma was induced by various concentrations of arachidonic acid and evaluated with respect to different phases in the aggregatory response. The drugs were rapidly absorbed and for both compounds the decline in plasma concentrations described two phases. Although concentrations of indoprofen were up to ten times higher than those of lonazolac, the two drugs were almost equally potent inhibitors of generation of TXB2, with IC50 for indoprofen of 1.4-1.5 X 10(-7) M and for lonazolac 2.1-3.0 X 10(-7) M. Their effects on the lag phase in platelet aggregation paralleled the inhibition of TXB2 formation. However, the rate and extent of aggregation were more inhibited by indoprofen than by lonazolac, and the discrepancy was greater than would be expected from concomitant values for TXB2 suppression. The rate of aggregation appeared to be the most sensitive variable, since the extent of aggregation followed an all-or-none pattern. The present results show that the concentrations reached after clinically used doses of antiinflammatory drugs may vary widely in relation to the concentrations needed for maximum inhibition of platelet cyclooxygenase. The results from aggregation tests may support the idea that non-steroid antiinflammatory drugs can differ in their mechanisms of action.     

Binding of bovine factor VIII-coated colloidal gold particles to receptors on platelet membranes

Bovine factor VIII/platelet aggregating factor was adsorbed into gold granules and the protein-gold complex added to either formalin-fixed or fresh washed human platelets. Following aggregation, binding of gold granules to the platelets was measured by monitoring the optical density of colloidal gold remaining in the supernatant. Scatchard analysis of binding data indicated that multiple classes of binding sites were present. The number of high affinity binding sites per formalin-fixed platelet depended on the concentration of ristocetin: 420 gold granules were calculated to bind at 1.4 mg/ml of ristocetin, 610 at 0.6 mg/ml of ristocetin and 875 when no ristocetin was added. Fresh washed platelets bound 1350 granules per cell in the absence of ristocetin. We conclude that during platelet aggregation, induced by bovine factor VIII, the binding sites on the platelet surface are only partially occupied.     

刺五加茎时对血小板聚集功能的影响

刺五加茎叶的乙醇提取液相当于生药量25～70mg/ml,体外实验能明显地抑制ADP、胶原所诱导的家兔血小板聚集。家兔iv 700mg/kg,10min后明显抑制ADP诱导的家兔血小板聚集,大白鼠iv 1000mg/kg,30min后明显抑制ADP诱导的血小板聚集。体外实验可使家兔血浆复钙时间明显延长。