Alcohol-induced oxidative stress and reduction in oxidation by ascorbate/l-cys/ l-met in the testis, ovary, kidney, and lung of rat

Chronic exposure to high doses of alcohol results in many pathophysiologic changes in cellular function caused by the alcohol itself and the effects of its metabolism (ie, generation of acetaldehyde, nicotinamide adenine dinucleotide [NADH], free radicals, and oxidative stress). However, the role of each of these effects on the testis, ovary, kidney, and lung in chronic alcoholism must be investigated. It is hypothesized that cysteine-methionine and vitamin C might neutralize harmful compounds and potentiate the antioxidant capacity of the cell or tissue. In this study, rats were fed regular diets and were maintained in the following groups for 90 days: control group; alcoholic group (2.5 g of 50% ethanol/kg body wt administered intragastrically every other day); and alcoholic with antioxidant supplement group (2.5 g of 50% ethanol plus a solution containing 200 mg vitamin C, 100 mg cysteine, and 100 mg methionine/kg body wt administered intragastrically every other day). After treatment had been completed, rat blood, testis, ovary, kidney, and lung were taken for biochemical analysis. Mean alcohol level in the alcoholic group was raised (by 40%) compared with that in the control group, but it was lower (by 30%) in the antioxidantsupplemented group than in the alcoholic group. In accordance with the levels of alcohol, oxidized protein and lipid content in the testis, ovary, kidney, and lung were low in the control group, higher in the antioxidant-supplemented group, and highest in the alcoholic group. It is interesting to note that levels of glutathione in the testis and lung of the alcoholic group were lower than those in both the control and antioxidant-supplemented groups. In conclusion, chronic alcohol administration led to a significant increase in the level of protein oxidation in the ovary and kidney of rats. Simultaneous intake of ascorbate/l-cys/l-met, along with ethanol, partly attenuated the amount of lipid and protein oxidation that occurred in tissues with oxidative stress caused by alcohol consumption.     

Ethanol enhances the inhibitory effect of an oral GPIIb/IIIa antagonist on human platelet function

Ethanol is a commonly used substance that can significantly influence platelet responses when combined with therapeutic drugs. In in vitro studies, we combined ethanol with LY309562, a novel 2,6-disubstituted isoquinolone RGD mimic that competes for fibrinogen binding to GPIIb/IIIa. Ethanol inhibits aggregation and secretion, partly by inhibiting thromboxane A(2) formation. We measured aggregation and secretion of dense granule contents by platelets labeled with [(14)C] serotonin in plasma from blood anticoagulated with FPRCH(2)Cl (PPACK). Alone, LY309562 dose-dependently inhibited aggregation induced by 10 micromol/L adenosine diphosphate, 1 microg/mL collagen, 2 micromol/L U46619 (a thromboxane A(2) mimetic), or 15 micromol/L SFLLRN (protease-activated receptor-1-activating peptide); inhibition was complete at 1 micromol/L LY309562 and partial at 0.1 micromol/L (50% inhibitory concentration [IC(50)] 0.19-0.33 micromol/L). Secretion induced by collagen, U46619, and SFLLRN was also inhibited by LY309562 (IC(50) 0.08-0.31 micromol/L). At inhibitory concentrations of LY309562, ethanol (2 or 4 mg/mL) further inhibited responses to collagen, U46619, and SFLLRN (IC(50) for aggregation 0.12-0.16 micromol/L; for secretion 0.04-0.12 micromol/L). Responses of aspirin-treated platelets to U46619 were also inhibited, indicating that ethanol was not acting solely by inhibiting thromboxane A(2) formation. Because it is likely that our results with LY309562 are representative of results with other GPIIb/IIIa antagonists, our in vitro data suggest that the concomitant use of GPIIb/IIIa antagonists and consumption of alcoholic beverages may result in further impairment of platelet participation in hemostasis and thrombosis.     

Depending on their concentration oxidized low density lipoproteins stimulate extracellular matrix synthesis or induce apoptosis in human coronary artery smooth muscle cells.

Various lines of evidence indicate that oxidative stress resulting in lipid peroxidation and protein modification is involved in the pathogenesis of atherosclerosis and coronary heart disease. We have investigated the effect of modified (oxidized) low-density lipoproteins (oxLDL) on collagen and fibronectin synthesis in cultured human coronary artery smooth muscle cells (HCA-SMC). As shown by immunofluorescence microscopy and time-resolved fluorescence immunoassay, oxLDL dose-dependently stimulated collagen type I and fibronectin synthesis in cultured HCA-SMC. The effect on matrix synthesis was biphasic, with a maximum effect at concentrations between 1 and 10 microg/ml oxLDL. Higher oxLDL concentrations (>25 microg/ml) were cytotoxic. Beside oxLDL, malondialdehyde-modified LDL also stimulated extracellular matrix synthesis. In the presence of 100 microg/ml ascorbic acid, 25, 50 and 100 microg/ml oxLDL induced apoptosis within 6-8 hours (demonstrated by TUNEL-reaction, annexin-V binding and APO-2.7-expression). Apoptosis was not induced by normal (unmodified) LDL and malondialdehyde-modified LDL. The radical scavengers and antioxidants TROLOX and probucol and the hydrogen peroxide eliminator catalase significantly reduced oxLDL-induced apoptosis. Our results demonstrate that low concentrations of oxLDL are profibrogenic by stimulating extracellular matrix synthesis, whereas higher oxLDL concentrations induce oxidative stress and apoptosis in coronary artery smooth muscle cells. The profibrogenic effect might be relevant in the formation of atherosclerotic plaques, and the proapoptotic effect might contribute to an increased plaque vulnerability.     

Effect of indobufen on whole blood platelet aggregation recorded in the morning in patients with ischaemic heart disease

Platelets are involved in the progression of coronary atherosclerosis as well as in the development of the acute precipitating event. Recently, it has been shown that normal subjects present increased platelet aggregation between 6.00 a.m. and 9.00 a.m.; epidemiological studies have shown a higher incidence of myocardial infarction between these times. This study evaluated, by an impedence method using whole blood, platelet aggregation induced by ADP (3 microM) and collagen (2 microM/ml). Measurements were made at 6.00 a.m., 9.00 a.m. and 12.00 noon, the day before and the day after evening administration of 200 mg indobufen, a platelet aggregation inhibitor, in 12 patients with ischaemic heart disease. Patients showed a significant increase of platelet aggregation between 6.00 a.m. and 9.00 a.m. which was inhibited by the prior evening administration of indobufen.     

加兰他敏对急性酒精中毒大鼠海马神经元NMDAR2B的影响

目的：探讨加兰他敏对急性酒精中毒大鼠海马神经元N-甲基-D-天冬氨酸（NMDA）·R2B的影响。方法：将60只大鼠分为对照组、酒精组及加兰他敏组,每组各20只。酒精组以50%（v/v）酒精12 mL/kg灌胃两次/日,共7d。加兰他敏组酒精（浓度、剂量同上）灌胃的同时腹腔注射加兰他敏2mg/kg一次/日,共7d。对照组以等量生理盐水灌胃。实验第8天取大鼠海马区做苏木精-伊红（HE）染色,观察海马区的病理学变化;免疫组织化学采用SABC法,观察海马区神经元NR2B的表达。结果：病理学观察结果：对照组海马区神经细胞排列整齐,胞质淡染,无变性、坏死;酒精组神经细胞层次不清、排列松散、细胞数量减少,部分细胞变性;加兰他敏组神经细胞层次较清、排列较密,细胞数目较酒精组增;免疫组织化学结果：酒精组与对照组比较NR2B阳性表达细胞数量明显减少（P〈0.01）;加兰他敏组与酒精组比较NR2B阳性表达细胞数量明显增高（P〈0.05）;加兰他敏组与对照组比较NR2B表达细胞数量无明显差异（P〉0.05）。结论：急性酒精中毒与海马区神经细胞的NR2B表达下调有关;加兰他敏具有保护急性酒精中毒导致的大鼠海马区神经细胞毒性的作用,其机制可能与加兰他敏上调NR2B的表达有关。     

Reduction in the incidence of thrombosis by the thromboxane synthetase inhibitor CGS 13080 in a canine model of coronary artery injury

The antithrombotic potential of the thromboxane (TX) synthetase inhibitor CGS 13080 (CGS) was studied in an anesthetized open-chest canine model of coronary artery intimal wall injury induced by the local application of a low amperage electrical current (100 microA for 6 hr). CGS was administered by i.v. infusion (1 mg/kg/min) beginning 30 min before applying the direct current to the intimal wall of the vessel. CGS did not alter basal values for heart rate, blood pressure or coronary blood flow. After 6 hr of current application to the vessel, 1 of 10 CGS-treated dogs exhibited complete thrombotic occlusion of the circumflex coronary artery compared to 8 of 10 nontreated control dogs (P less than .01). Thrombus masses within the injured left circumflex coronary artery were: Control, 25.9 +/- 4.5 mg (n = 10) and CGS, 11.0 +/- 2.8 mg (n = 10); P less than .01. The concentration of TXB2 determined ex vivo in serum from thrombin-activated whole blood was decreased by CGS administration: Control, 43.15 +/- 16.08 ng/ml (n = 9) vs. CGS, 1.72 +/- .69 ng/ml (n = 10); P less than .001. Ex vivo platelet aggregometry demonstrated that arachidonic acid (0.65 mM)-induced aggregation was reduced from a control value of 82.3 +/- 7.8% (n = 10) to 45.0 +/- 11.3% (n = 10) (P less than .05), whereas aggregation in response to ADP (5 micrograms/ml) or collagen (156 and 312 micrograms/ml) was unaffected. CGS was compared with two other TX synthetase inhibitors, U63557A and OKY1581, for the ability to divert cyclic endoperoxide metabolism to the synthesis of prostaglandin (PG) E2 and prostacyclin in response to stimulation of whole blood in vitro with collagen (25 micrograms/ml). CGS, U63557A and OKY 1581 were found to be equally effective with respect to PGE2 and 6-keto PGF1 alpha production in vitro. The data demonstrate that CGS is an effective antithrombotic agent in vivo and that it selectively inhibits arachidonic acid-induced platelet aggregation ex vivo and the formation of TXA2 in thrombin-activated whole blood.     

Effects of fluvoxamine on ethanol-reinforced behavior in the rat

Serotonergic deficiencies have been associated with alcoholism, and increasing serotonin function has been reported to decrease ethanol consumption. In this study, we examined the effects of the selective serotonin reuptake inhibitor, fluvoxamine, upon ethanol self-administration in the rat, and as a test of specificity also examined the effects of fluvoxamine upon food-maintained behavior. Fluvoxamine decreased ethanol-maintained (0.1 ml per dipper presentation, 4-32% w/v ethanol) behavior at lower doses than the doses needed to decrease food-maintained (2 x 45-mg pellet) behavior. Examination of the behavioral interactions of ethanol and fluvoxamine upon food-maintained behavior showed that these observations did not result from synergistic behavioral actions that would occur during ethanol-maintained, but not food-maintained, behavior. Also, fluvoxamine did not alter the potency or efficacy of ethanol to occasion ethanol-appropriate responding in rats trained to discriminate 1.2 g/kg ethanol from vehicle. These findings suggest that fluvoxamine has specific actions upon the reinforcing effects of ethanol.     

Influence of thiamine deficiency on the response to ethanol in two inbred rat strains

We investigated whether thiamine deficiency (TD), a frequent concomitant of chronic alcoholism, differentially modifies the response to ethanol in two inbred rat strains with highly different genetic susceptibilities to development of TD encephalopathy. Ethanol-induced (3 g/kg i.p.) behavioral impairment and hypothermia were studied after 2, 5 and 7 weeks of TD and after 6 weeks of repletion on normal diet. Controls of the M520/N (TD-sensitive) strain metabolized ethanol more rapidly, had a greater liver to body weight ratio, greater total body water, earlier and lower peak blood ethanol concentrations (BEC), diminished area under the BEC curve and lesser behavioral impairment and hypothermia (even at equivalent BEC values) than those of the F344/N (TD-resistant) strain. In both strains, TD resulted in reduced ethanol metabolic rate and liver to body weight ratio and equivalent ethanol-induced hypothermia and behavioral impairment at lower BEC. Lower and delayed peak BEC and unchanged area under the BEC curve suggest an increased volume of ethanol distribution during TD. Recovery appeared complete after 6 weeks of normal diet. Both strains lost an equivalent proportion of body weight during TD but M520/N rats had lesser decrements in ethanol metabolic rate, had greater reductions in liver weight, peak BEC and baseline body temperature and developed overt encephalopathy whereas F344/N rats did not. Therefore, in the chronic alcoholic, TD may modify ethanol's effects via pharmacokinetic and pharmacodynamic mechanisms. Relatively high ethanol tolerance of the strain with a genetic predisposition to TD encephalopathy is consistent with the hypothesized role of this avitaminosis in the pharmacogenetics of alcoholism.     

Acetaldehyde-modified hemoglobin as a marker of alcohol consumption: comparison of two new methods.

We examined the diagnostic value of acetaldehyde-hemoglobin adducts in the detection of heavy drinking and alcoholism. Acetaldehyde adducts from red cells were measured by new chromatographic and immunologic methods. The study population included 20 men with well-documented histories of chronic alcoholism, 18 men who were heavy drinkers, 22 male healthy control subjects, and 8 control subjects with liver disease that was not related to alcohol use. In addition, 20 healthy volunteers and 5 control subjects participated in the study to determine the effect of an acute dose of ethanol. The results that were obtained by the two new methods correlated significantly (r = 0.38, p = 0.002). With both methods, the concentrations of acetaldehyde-hemoglobin adducts were found to be significantly higher in red cells of heavy drinkers (p less than 0.001) and subjects with alcoholism (p less than 0.001) when compared with control subjects. Acetaldehyde-modified hemoglobins appear to have at least the same sensitivity (chromatographic determination = 50% and immunologic determination = 50%) to detect heavy drinking as the most widely accepted conventional biochemical markers of alcohol abuse, gamma-glutamyltransferase (39%) or mean corpuscular volume (17%). In a group of 20 healthy volunteers, acetaldehyde-hemoglobin adducts increased significantly even after a single high dose of ethanol (2 gm/kg), whereas there was no change in the conventional markers of alcohol consumption at the same time. Acetaldehyde-hemoglobin adducts assays should be useful for the detection of heavy drinking in clinical settings.     

Nonsteroidal anti-inflammatory drugs and aspirin: a comparison of the antiplatelet effects.

Antiplatelet effects of common analgesics were assessed in vitro. The Streck Platelet Aggregation Test Kit (Omaha, NE) was used to measure percent platelet aggregation in response to sodium arachidonate, collagen, adenosine diphosphate, and ristocetin in patients on various analgesics. In comparison with the control group, the response to arachidonate and collagen of ibuprofen (86% vs. 33% and 55% vs. 23%), naproxen (86% vs. 43% and 55% vs. 29%), indomethacin (86% vs. 26% and 55% vs. 17%), and aspirin (86 vs. 21% and 55 vs. 23%) all demonstrated a significant yet comparable reduction in platelet aggregation (p < 0.01). Because of the comparable antiplatelet effects of aspirin and NSAIDs, the additional benefits of daily aspirin in those patients on chronic and consistent NSAID therapy must be reconsidered.     

Alcoholic bile does not intensify acute pancreatitis in rats

The toxicity of intraductal injections of normal bile, bile obtained from rats receiving ethanol i.v., and normal bile mixed with ethanol at a concentration of 1.5 g/l to the pancreas were tested using male Wistar rats (n = 60). The animals were killed by exsanguinating the abdominal aorta 24 h after the induction of acute pancreatitis by a retrograde infusion into the pancreatic ducts, the pancreases resected, and histological samples taken from the constant place of the pancreas. The histological specimens were classified according to the degree of severity of pancreatitis. No statistically significant differences in the severity of acute pancreatitis were observed between the groups. In conclusion, ethanol given i.v. or ethanol mixed with normal rat bile do not increase the toxicity of an intraductal bile injection to the pancreas. Thus, the previously observed increased toxicity of alcoholic bile obtained from chronic alcoholic rats must be mediated by a change of some metabolites of bile.     

Nitric oxide pathway, Ca2+, and serotonin content in platelets from patients suffering from chronic daily headache

An alteration in serotonin concentration has been found in patients with chronic headache caused by abuse of analgesic substances as well as an up-regulation of 5HT2 platelet receptors, which has been correlated with chronicization of the headache. In a previous study we demonstrated an increase in L-arginine/nitric oxide (NO) pathway activity in platelets from patients affected by migraine with or without aura, particularly during attacks. In the present research we assessed the variations in platelet L-arginine/NO pathway and cyclic guanosine monophosphate (cGMP) levels in 32 patients affected by chronic daily headache (CDH) (8 M, 24 F, age range 34-50 years) both during and between attacks. In these same patients, the platelet aggregation to different collagen concentrations (0.3, 1, 3 micrograms/ml) was determined as well as the intracellular platelet calcium concentration using fluorescence polarization spectrometry. These parameters were compared with those of an age- and sex-matched control group (n = 25; n = 10, n = 15, age range 35-51 years). A reduction found in platelet aggregation response to each collagen concentration used (p < 0.001) was coupled with an increased NO and cGMP production (NO: p < 0.0001; cGMP: p < 0.001). This was accompanied by a significant increase in intracytosolic Ca2+ (p < 0.0001) concentration and a reduced platelet serotonin content compared to those in control individuals (p < 0.0002). Changes in the above platelet parameters were accentuated more in patients with analgesic abuse than in CDH patients with no drug abuse. These findings suggest the occurrence of an activation of cGMP-Ca2+ mediated events in CDH patients with analgesic abuse. This physiologic compensatory mechanism, which intervenes in overcoming the increase in cytosolic Ca2+ levels, is not as efficient at limiting serotonin depletion by platelet dense bodies. A similar depletion in the central serotoninergic pathway can be assumed in the same patients.     

Effect of acetaldehyde on rat platelet aggregation in vivo and in vitro

The effect of acetaldehyde on primary hemostasis and platelet aggregation was studied in vivo and in vitro in the rat. Acetaldehyde was found in circulation following ethanol intoxication or was present after direct i.v. injection. In vitro, acetaldehyde was added to whole blood or platelet plasma suspension. Bleeding time and blood loss were increased upon ethanol intoxication and immediately after i.v. infusion of acetaldehyde. The intrinsic coagulation system, assayed by APT-time, was unaffected. In vivo, ADP and collagen-induced platelet aggregation was inhibited upon the presence of acetaldehyde. In vitro, inhibition of platelet aggregation was observed when acetaldehyde was added to blood, while the addition of the compound to plasma did not affect platelet function.     

Low-dose ethanol consumption allows strength recovery in chronic alcoholic myopathy

Chronic skeletal myopathy may affect one third of chronic alcohol misusers. It is generally accepted that abstinence allows partial recovery, and that continued high-dose ethanol consumption progressively deteriorates muscle function. However, the effect of low-dose ethanol consumption in alcoholic myopathy has not been studied. We studied 58 chronic alcoholic male patients with biopsy-proven chronic alcoholic myopathy over 5 years. We evaluated ethanol intake, biochemical and nutritional parameters, and assessed muscle strength. Eighteen patients who remained abstinent showed marked improvement in muscle strength. As expected, the 19 patients who persisted in high-dose ethanol consumption further diminished in their muscle strength. In the 11 patients who maintained low-dose (相似文献   

Coronary artery bypass grafting ameliorates the decreased plasma adiponectin level in atherosclerotic patients

Adiponectin functions as an anti-inflammatory and anti-atherogenic factor, and the decreased plasma adiponectin is a risk factor for coronary disease. The aim of this study was to determine the changes in plasma levels of adiponectin, a potential parameter for atherosclerosis, in patients underwent surgical revascularization. We included forty patients with atherosclerosis (age, 58 +/- 9 years; body mass index [BMI] 26.93 +/- 2.3 kg/m(2)) undergoing coronary artery bypass grafting (CABG). Control group consisted of 40 healthy volunteers, matched for age, gender and BMI (age, 56 +/- 6 years; BMI, 26.78 +/- 2.3 kg/m(2)). We measured various parameters, including high sensitive C-reactive protein (hsCRP), homeostasis model assessment-insulin resistance (HOMA-IR) indexes, and adiponectin. The baseline profile of the patients before CABG showed higher levels of serum hsCRP (13.15 +/- 2.40 mg/l vs 3.97 +/- 1.07 mg/l) and HOMA-IR (1.86 +/- 0.30 vs 1.26 +/- 0.33) and lower plasma adiponectin levels (7.02 +/- 2.01 microg/ml vs 25.46 +/- 3.9 microg/ml), compared to controls (p < 0.001 for each parameter). Plasma adiponectin level was increased one month after CABG from the baseline level to 8.67 +/- 2.05 microg/ml(p < 0.001), although the level was still lower than the control value. Thus, postoperative adiponectin level might be helpful for evaluating the progression of atherosclerosis. Moreover, CABG significantly decreased hsCRP to 7.25 +/- 1.89 mg/l and HOMA-IR to 1.59 +/- 0.33, although these levels were higher than the controls. These results suggest that CABG decreases the cardiac risk factors in atherosclerotic patients.     

Platelet aggregation response and adenosine triphosphate secretion after abdominal total hysterectomy

This study was designed to clarify the quantitative relationship between platelet aggregation and the secretion of adenosine triphosphate (ATP) after surgery. Peripheral blood was collected from 41 patients who underwent abdominal total hysterectomy. Platelet count, volume, aggregation and the amount of secreted ATP were determined using live platelets before, one day after and two weeks after surgery. Platelet aggregation and ATP secretion were investigated using a lumi-aggregometer. The aggregating reagents used were 5 microM of adenosine diphosphate (ADP) (final concentration) and 5 microg/ml of collagen. Structural alterations of platelets at these time points were also investigated by electron microscopy. Platelet aggregation induced by collagen was significantly lower (p<0.05) one day after surgery. ADP-induced aggregation two weeks after surgery was more intense than before (p<0.05) and one day after (p<0.05) surgery. The amount of secreted ATP induced by each of ADP and collagen was significantly lower (p<0.05-0.01) one day after surgery and correlation coefficients between platelet aggregation and secretion of ATP showed lower values in both ADP- and collagen-induced aggregation. One day after surgery electron microscopy showed that granule concentrations were markedly reduced in platelets. In conclusion, after consumption of circulating platelets at the site of operation, in addition to being lost by bleeding, the remaining platelets in circulation consist of platelet subpopulations different from those present before surgery, exhibiting low values of correlation coefficients between platelet aggregation and secretion of ATP and low concentrations of granules.     

Physiological interactions between diet and exercise in the etiology and prevention of ischaemic heart disease

Modern eating habits and sedentary life-style interact to promote atherosclerosis and increase risk of ischemic heart disease (IHD). Apparent sites of interaction affecting severity of coronary atherosclerosis are body weight, blood lipid-lipoproteins, blood pressure, glucose-insulin dynamics, and platelet aggregation. In addition the conditioning effects of physical activity on the heart and adrenergic system reduce myocardial oxygen and coronary blood flow requirements, and raise the threshold for ischemia and ventricular dysrhythmias in the presence of existing coronary atherosclerosis. Dietary recommendations to reduce risk factors for IHD are to decrease intake of total and saturated fat, cholesterol, and sodium, increase intake of complex carbohydrates of plant origin and polyunsaturated fatty acids from vegetable oils and fish, adjust energy intake to maintain or achieve desirable body weight, and keep alcoholic consumption low. Epidemiologic evidence also suggests that risk of IHD can be further reduced with 30 to 60 minutes/day of even light or moderate intensity physical activity, including working around the home and yard, walking, exercise or sports. An optimal daily energy expenditure for IHD prevention appears to be between 150 and 300 kcal/day.     

冻干血小板再水化后聚集

本研究旨在观察冻干血小板再水化后聚集反应性变化。以4种不同浓度的凝血酶、瑞斯托霉素、ADP、胶原作诱导剂,使用APACT2型血小板聚集仪,检测冻干再水化和新鲜血小板的最大聚集率,以ADP为诱导剂,检测胞内外海藻糖对再水化冻干血小板最大聚集率的影响。结果表明当凝血酶、瑞斯托霉素、ADP、胶原浓度分别为1U/ml、1.6mg/ml、20μmol/L、2μg/ml时,新鲜血小板最大聚集率达100%左右,冻干再水化血小板最大聚集率分别达(70.17±7.36)%、(15.3±2.81)%、(68.67±6.86)%、(64.67±11.6)%。胞内外海藻糖组、胞外海藻糖组、空白对照组冻干再水化血小板最大聚集率分别达(66.0±4.69)%、(25.3±2.42)%、(11.5±1.87)%(P<0.01)。结论凝血酶、瑞斯托霉素、ADP、胶原浓度分别为1U/ml、1.6mg/ml、20μmol/L、2μg/ml可作为血小板聚集实验的合适浓度,胞内外海藻糖使冻干再水化血小板最大聚集率显著提高。     

Collagen-Mediated Platelet Aggregation EFFECTS OF COLLAGEN MODIFICATION INVOLVING THE PROTEIN AND CARBOHYDRATE MOIETIES

In an effort to elucidate the nature of the collagen-platelet interaction, the effects of collagen modification on platelet aggregation have been studied. We have shown that purified rat skin (salt) soluble collagen is effective at about 20 nM in mediating platelet aggregation in human platelet-rich plasma. This concentration is somewhat greater than that required of several skin insoluble collagens (ca. 10 nM). Both the alpha1(I) and alpha2 chains from rat skin soluble collagen produced platelet aggregation, but only at concentrations of about 13 muM and 55 muM, respectively. In contrast, heat-denatured collagen and chains (e.g., 65 muM alpha1(I) and 160 muM alpha2) failed to induce platelet aggregation and to inhibit platelet aggregation by native collagen.Glycopeptides were prepared from human skin insoluble collagen by extended digestion with bacterial collagenase and trypsin, and were purified by gel filtration into two classes. One class of higher molecular weight contained sialic acid, glucosamine, galactosamine, fucose, mannose, galactose, and glucose, and the other of lower molecular weight consisted primarily of a mixture of galactose and galactosyl-glucose units O-glycosidically linked to hydroxylysine-containing peptides. We found that, after the residual tryptic activity contaminating the higher molecular weight fraction was inhibited, neither of the glycopeptide classes produced nor inhibited native human skin insoluble collagen-mediated platelet aggregation at the highest concentration examined (ca. 1-2 mg glycopeptide per ml of platelet-rich plasma).Highly purified samples of the hydroxylysyl glycosides, hydroxylysylgalactose and hydroxylysylgalactosylglucose (Hyl-Gal and Hyl-Gal-Glc, respectively), were prepared from human urine and labeled at galactose using galactose oxidase followed by reduction with tritiated borohydride. Binding studies with platelet-rich plasma showed that, at concentrations greater than 50 nM, Hyl-Gal gives apparent binding to platelets, but there was no evidence of Hyl-Gal-Glc binding to platelets at concentrations up to 250 nM. At concentrations several hundredfold higher than the equivalents present in the minimum concentration of rat skin soluble collagen required for platelet aggregation, neither Hyl-Gal (at 29 muM) nor Hyl-Gal-Glc (at 18 muM) caused platelet aggregation or inhibited platelet aggregation by native collagen. Also, at a concentration of 85 muM (which represents a concentration about two thousandfold higher than the equivalents in the minimum concentration of soluble collagen required for platelet aggregation) the Gal-Glc-containing 36 residue rat skin soluble collagen alpha1(I)cyanogen bromide #5 peptide had no platelet aggregating or inhibiting activity.Modification of at least 90% of the rat skin soluble collagen carbohydrate by mild periodate oxidation had no effect on the platelet aggregating activity. Human skin insoluble collagen was reacted with periodate under the same conditions, and this had no demonstrable effect on its ability to induce platelet aggregation. This indicates that the normal carbohydrate side chains of these collagens are not required for the platelet interaction that produces the release of ADP and other metabolic constituents and leads to aggregation.Thus, collagen-platelet interactions appear to involve at least two distinct binding sites on the platelet plasma membrane. One is a protein binding site that activates platelet aggregation and has high specificity and affinity for the collagen triple-helical fold or perhaps even for a particular amino acid sequence in the triple helix.     

Effect of fluvastain and its combination with aspirin and trental on hemostasis and microcirculation in atherosclerosis

AIM: To assess effects of fluvastatin monotherapy and combined therapy with aspirin and trental on hemostasis and microcirculation in atherosclerosis. MATERIAL AND METHODS: Hemostasis and microcirculation were studied in 68 patients with coronary atherosclerosis and aortic atherosclerosis on fluvastatin monotherapy and on combined therapy fluvastatin + aspirin + trental. RESULTS: Hypolipidemic treatment with fluvastatin reduced thrombogenic blood potential due to enhancement of plasmic fibrinolytic activity [the time of XII-a dependent fibrinolysis decreased by 33% (p < 0.05)], decreased thrombinemia [blood level of soluble fibrin-monomeric complexes fell by 44% (p < 0.05)] and reduced stimulated platelet aggregation: by 18.2% in response to ADP (p < 0.05) and by 11% in response to adrenalin (p < 0.05). CONCLUSION: Correction of lipid metabolism and blood hypercoagulation improved microrheology. Combination of fluvastatin with aspirin made platelet aggregation reduction in response to both inductors faster and more stable, while combination of fluvastatin with trental contributed to better results in microcirculation improvement.