摘要:

The light scattering extinction coefficients and kinetic rate constant(s) for the disc to sphere and the sphere to (smaller) ‘spiny sphere’ shape changes induced in platelets by saturating amounts of ADP are compared at 31, 37 and 41 °C. Platelets exhibit optimum efficiency at 37 °C, as judged by not only the rates of the shape changes but also by alterations in the overall sizes and shapes of the three platelet forms. Unstimulated (discoid) platelets appear to be flatter at 37 °C, the disc to sphere reaction appears to be impaired at other than 37 °C, and the pseudopodia which characterize the final spiny sphere may be more prominent a

ISSN:1424-8832    

DOI:10.1159/000214819

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Thrombin-induced platelet activation is enhanced by very low and low density lipoproteins but decreased by high density lipoprotein. Plasma lipoproteins maximally affect platelet aggregation and 14C-serotonin release in a gel-filtered platelet preparation within 10 min of incubation at 37 °C. This effect is saturable and physiologic concentrations of lipoproteins are required in order to attain this saturation. When no aggregating agent is added to the incubation medium, the lipoproteins alone did not alter platelet aggregation. However, 14C-serotonin release is increased by very-low- and low-density lipoproteins alone more than by high density Hpoprotein. On removal of the lipoproteins after incubation with the platelets, and subsequent testing of platelet function, minimal influence of these lipoproteins on the platelet function remains. Arachidonic acid causes similar results to thrombin when added to the platelet suspension after incubation with the lipoprotein. Our results further emphasize the Opposing effects’ of very low and low density lipoproteins as compared to high density lipoproteins on platelets and/or platelet-thrombin interacti

ISSN:1424-8832    

DOI:10.1159/000214820

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Recently, conflicting results have been published about a possible relationship between platelet activity and exercise-induced myocardial ischemia. The present study was performed to investigate platelet behavior during a graded symptom-limited bicycle ergometer test both in relation to the intensity of exercise and to exercise-induced myocardial ischemia. Plasma concentrations of platelet factor 4 (PF4) and β-thromboglobulin (β-TG) were measured by radioimmunoassays in 53 patients who had had acute myocardial infarction 10 weeks before the study and, for comparison, in 9 healthy individuals. In the whole group of the 53 patients there was no significant alteration in platelet-specific proteins during exercise, whereas physical activity induced a 2- to 3-fold increase in β-TG and PF4 levels in the controls. However, on differentiation of the patients as to their individual exercise performance, significant exercise-associated platelet activation was demonstrable in those who reached more than 75% of their calculated maximal working capacity, whereas no correlation was found between platelet activity and exercise-induced myocardial ischemia. Thus, the results from this study indicate that in vivo platelet activation is a physiological phenomenon which occurs when a certain degree of physical intensity is exceeded, independent of the precipitation of myocardial ischem

ISSN:1424-8832    

DOI:10.1159/000214821

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

In tissue sections of human hyperplastic as well as carcinomatous prostate glands ñbrinolytic activity could be attributed to collecting ducts and vessel walls. Inhibition studies with antibodies directed against human urokinase (u-PA) or tissue plasminogen activator (t-PA) revealed the presence of a plasminogen activator completely inhibitable by anti-t-PA IgG in the vessel walls, while in collecting ducts the plasminogen activator activity was inhibited by anti-u-PA IgG to only 80% and by anti-t-PA IgG to about 20%. A mixture of anti-u-PA and anti-t-PA IgG was able to inhibit fibrinolytic activity in collecting ducts completely. In carcinomatous prostate glands total fibrinolytic activity was significantly higher, but localization and relative contribution of anti-u-PA-inhibitable and anti-t-PA-inhibitable plasminogen activators remained the same

ISSN:1424-8832    

DOI:10.1159/000214822

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Crude, commercial thrombin preparations and purified bovine thrombin were incubated with normal human reference plasma and the amount of thrombin inactivated was calculated. 1 ml of human plasma inactivated 140–193 NIH U of the various crude thrombin preparations. In the presence of heparin, a lower thrombin-inactivating capacity of plasma was confirmed using crude thrombin, but this phenomenon was less pronounced with the purified thrombin preparation. The molar concentration of the purified bovine thrombin was determined by active site titration. Comparing with protein concentration (A280 this preparation was 92% pure. 1 ml of human plasma inactivated 2.57 µmol of thrombin in the absence of heparin, and 2.50 µmol with heparin. Assuming 1:1 stoichiometry in the thrombin-antithrombin reaction, these results suggest that the concentration of antithrombin in the pooled reference plasma is approximately 2.57 µmol/l or 0.15

ISSN:1424-8832    

DOI:10.1159/000214823

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Isoelectrofocusing was carried out in the LKB Multiphor apparatus with pH 4–6.5 carrier ampholines using polyacrylamide gel slabs. Specimens of purified antithrombin III (AT-III), normal plasma and serum were isoelectrofocused. Microheterogeneity was shown by three preparations of purified AT; the protein was separated in at least six bands, three large bands were located in the pH range 4.9–5.2, one intermediate band at pH 4.85, other thinner bands were located in the pH range 4.55–4.80. The microheterogeneity of AT-III was confirmed in purified preparations as well as in plasma and in serum by crossed immunoelectrofocusing. The pattern of purified preparations, normal plasma and serum were very similar; only minor, quantitative differences were noticed. Plasma from a patient with congenital AT-III deficiency showed an abnormal pa

ISSN:1424-8832    

DOI:10.1159/000214824

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The effects of FUT-175 (6-amidino-2-naphthyl-4-guanidino benzoate-dimethanesulfonate), a new synthetic protease inhibitor, on endotoxin-induced experimental disseminated intravascular coagulation (DIC) were studied in rats. Experimental DIC was induced by a 4-hour sustained infusion of endotoxin at a dose of 100 mg/kg. The rats were infused continuously with FUT-175 at 0.001, 0.01, 0.1, 1.0 or 10.0 mg/kg into a femoral vein for 4 h. Simultaneously with the agent infusion, endotoxin (100 mg/kg/4 h) was administered into the contralateral femoral vein. A protective effect against DIC was noted in the rats treated with 0.01 or 0.1 mg/kg of FUT-175 in the following parameters: fibrinogen and fibrin degradation products, fibrinogen level, prothrombin time, partial thromboplastin time, platelet count and the number of renal glomeruli with fibrin thrombi. These results demonstrated that FUT-175 reduces the extent of changes of the coagulation parameters caused by DIC.

ISSN:1424-8832    

DOI:10.1159/000214825

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Bleeding time, platelet count and haematocrit were performed in 64 normal, anaemic and polycythaemic subjects with normal renal function and platelet counts over 100 B× 109/l. There was a significant inverse correlation between the bleeding time and haematocrit (r = -0.47) and an inverse correlation of the haematocrit and platelet count (r = -0.46). We suggest that the effect of the haematocrit on the bleeding time could explain the shorter bleeding time in men compared to women, and the shorter bleeding time in subjects with arterial disease, in whom an increased haematocrit is commonly found

ISSN:1424-8832    

DOI:10.1159/000214826

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Radiocontrast molecules (RCM) used in coronaroangiography and/or urography diminished their osmotic fragility when they were incubated for 30 min with human erythrocytes. The shift of the osmotic fragility curve towards lower NaCl concentration is related to the hypertonicity of RCM, but in addition, at a given osmolality (100 ± 5 mosm/kg), RCM at the concentration of 4–10% v/v increase the resistance to osmotic lysis or even suppress it. Similar protection is observed towards erythrocyte lysis induced by a detergent (saponin), polyenic antibiotic (filipin) or non-polyenic cholesterol-specific agent (digitonin). The effect is (1) proportional to the amount of RCM present, (2) independent of hypertonicity of the molecule, and (3) related to the nature of acidic molecules. A weak insertion of RCM into the erythrocyte membrane is suggested since it was suppressed by a single washing of the cel

ISSN:1424-8832    

DOI:10.1159/000214827

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

A double-blind, randomized, placebo-controlled clinical trial was conducted to determine whether fibrinolysis was increased by the chronic administration of aspirin or diflunisal. Healthy male and female volunteers were randomized to receive either aspirin (1,300 mg every 12 h; 10 subjects), diflunisal (1,000 mg initially, then 500 mg every 12 h; 10 subjects), or placebo (10 subjects) for 8 days. Fibrinolytic activity was examined with the clot lysis assay, using native whole blood, platelet-rich plasma, and platelet-poor plasma, and with the kaolin-activated euglobulin lysis test. In addition, measurements were made of fibrinogen, fibrin/fibrinogen degradation products, plasminogen, and the thrombin time. Clot lysis was greater in whole blood and platelet-rich plasma than in platelet-poor plasma, and increased lysis was observed in specimens obtained in the afternoon as compared to those obtained in the morning. Fibrinolytic activity in the afternoon samples was significantly enhanced by both aspirin and diflunisal at the start of the trial (p < 0.05), but by the afternoon of day 8, only aspirin showed some enhancement. Fibrinolytic activity, as measured by the euglobulin lysis time, actually declined in all study groups during the course of drug administration. No significant changes were recorded in any of the other assayed hemostatic parameters. We conclude that aspirin and diflunisal exert a modest, nonsustained enhancing effect on fibrinolysis in normal subjects.

ISSN:1424-8832    

DOI:10.1159/000214828

出版商:S. Karger AG    

年代:1983

数据来源: Karger