摘要:

Interactions between blood platelets and polymorphonuclear leukocytes (PMN) influence cell reactivity. We have examined the effects of inhibiting platelet and PMN cyclooxygenase and lipoxygenase pathways, by treatment with aspirin (ASA) and salicylate (SAL) on platelet-vessel wall interaction studied under flow conditions by means of an annular chamber perfusion system. We have also measured the levels of cyclooxygenase-derived metabolites during perfusion. Perfusates were prepared with untreated and ASA- or SAL-treated PMN or platelets. Our results demonstrated that blockage of the lipoxygenase pathway in PMN significantly increased platelet thrombus formation and favored the production of thromboxane B2 (T×B2) during perfusion, whereas inhibition of cyclooxygenase pathway in PMN had no effect either on platelet deposition or on T×B2 levels. In contrast, blockage of platelet cyclooxygenase, which caused almost total inhibition of T×B2, enhanced platelet adhesion and did not modify platelet thrombus formation. These results suggest that under dynamic conditions cooperative metabolic mechanisms between platelets and PMN directly influence platelet interaction with vascular subendotheli

ISSN:1424-8832    

DOI:10.1159/000216845

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Accumulating evidence indicates that certain low-molecular-weight (LMW) heparins administered subcutaneously may replace classic intravenous heparin therapy. LMW heparins do not require monitoring and may be safer and more effective than unfractionated heparin. The decreased mortality rate, evident in two randomized trials, which was particularly striking in patients with metastatic carcinoma, requires confirmation. The simplified care offered by LMW heparin therapy raises the possibility of transferring care from in-hospital to out of hospital in uncomplicated patients with deep-vein thrombosis [Salzman EW: Low-molecular weight heparin and other new antithrombotic drugs. N Engl J Med 1992;326: 1017-1019]. The advantages to the patient of avoiding in-hospital care and its associated hazards are obvious. Outpatient LMW heparin therapy will likely prove to be highly cost-effective. It is uncertain at present whether the findings associated with an individual LMW heparin preparation can be extrapolated to a different LMW heparin. For this reason the findings of clinical trials apply only to the particular LMW heparin evaluated and cannot be generalized to the LMW heparins at large.

ISSN:1424-8832    

DOI:10.1159/000216901

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

This model of arterial thrombosis induced by laser was used to evaluate the effect of aspirin (Aspegic®) on embolization. A partial occlusion was induced in small mesenteric arterioles (diameter 35-40 μm) with an Argon Laser. The laser induced the formation of a vessel wall lesion with damage of endothe-lial cells. Thrombus formed within seconds after the laser lesion and grew rapidly. Embolization began within the minute following the laser flash. Thrombus formation and embolization were repetitive phenomena. The duration of embolization was 6.50 ± 0.84 min in the control group. Then the thrombus became stable and partially obstructed the vessel lumen. The administration of aspirin at three doses (50, 100, 200 mg/kg) by intramuscular injection, 15 min before the laser injury, induced three different phenomena: (1) an increase of the number of laser injuries required for the thrombus formation; (2) a dose-dependent decrease in the duration of embolization, and (3) a dose-dependent decrease in the number of emboli. The highest dose injected induced the strongest reduction in the duration of embolization and the number of embo

ISSN:1424-8832    

DOI:10.1159/000216846

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Thromboprophylaxis to surgical patients is generally accepted, and used in the perioperative period by many surgeons as effective means of reducing postoperative thromboembolic complications. Often the prophylaxis is stopped at the time of mobilization or discharge of the patient, although late thromboembolic complications after cessation of the postoperative prophylaxis are known to occur up to 7 weeks after surgery. By scrutinizing thromboprophylactic studies performed in general surgery during the last 20 years, we found the incidence of late thromboembolic complications reported to be about 1 % when clinical diagnostics was applied. In studies where the patients were screened for late thromboembolic complications using paraclinical diagnostic methods the incidence is 10 times higher. The clinical relevance of these late postoperative thromboembolic complications is still uncertain, as is the value of long-term prophylaxis.

ISSN:1424-8832    

DOI:10.1159/000216903

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The anticoagulant phenprocoumon (PH) and its metabolites 6-hydroxy-, 7-hydroxy- and 4′hydroxy-phenprocoumon (6-OH-PH, 7-OH-PH and 4′-OH-PH, respectively) were separately administrated intravenously as racemates to rats in order to measure the potential effects of the major metabolites of PH on coagulation. Plasma samples were assayed for total concentrations of the administered compounds and the corresponding prothrombin times; kinetic parameters and anticoagulant activities were estimated using a pharmacodynamic model based on the rate of synthesis of clotting factors. The relative potencies were in the order PH > 4′-OH-PH > 6-OH-PH > 7-OH-PH the latter showing no activity. Patients on PH therapy showed lower plasma concentrations of metabolites than of PH; in humans the metabolites of PH will not contribute significantly to the overall anticoagulant activity of the

ISSN:1424-8832    

DOI:10.1159/000216847

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Several studies have shown thromboprophylaxis of any kind to be more cost-effective than no prophylaxis or general diagnostic surveillance and selective treatment. Little has been written on low molecular weight heparins from the cost-effectiveness point of view. This preliminary study shows low molecular weight heparin to be more cost-effective than standard low-dose heparin in most situations of prophylaxis.

ISSN:1424-8832    

DOI:10.1159/000216904

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Coagulation factors that interfere with the one-stage prothrombin time (PT) were investigated. PT responded with identical activities (adequately) against coagulation factors VII or X, only half as expected against factor IX, less than expected and nonlinearly against factor II. In multiple coagulation factor deficiencies PT did not differ from factor VII, which was the most reduced coagulation factor in warfarin therapy or liver disease. PT may also be influenced by factor VII at high activities.

ISSN:1424-8832    

DOI:10.1159/000216848

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

253 outpatients were included in a prospective randomized study. All patients had incidences of injuries of the lower limb immobilized by a plaster cast. 126 patients (group I) received a subcutaneous injection of Fraxiparin daily, and 127 patients (group II) received no thromboprophylaxis. Without prophylaxis 21 (16.5%) cases developed a thrombosis, and with prophylaxis a thrombosis could be proven in 6 (4.8%) patients only (p < 0.01). Thus, for all patients with an injury of the lower limb being immobilized by a plaster cast, a thromboprophylaxis with a low-molecular-weight heparin is recommended.

ISSN:1424-8832    

DOI:10.1159/000216905

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

A new sensitive chromogenic heparin assay is developed, which is well suited for clinical use. For the assay two reaction mixtures are required which can be lyophilized and reconstituted on the day of use. These reagents are stable during at least 6 h. Only two time-dependent pipetting steps are necessary. Any compound that inactivates thrombin, or can potentiate thrombin inactivation by an inhibitor, can be measured with this assay, including standard heparin, low molecular weight heparins, hirudin, α-NAPAP, pentosan polysulphate and dermatan sulphate. It is shown that heparin can be measured accurately in whole blood and in plasma. By addition of dextran sulphate to one of the reagents a platelet factor 4-insensitive assay is developed, so heparin can be measured even in blood that is partially activated and thus contains platelet factor 4 which neutralizes heparin

ISSN:1424-8832    

DOI:10.1159/000216849

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Recently there has been an increasing interest in long-term prophylaxis as it has become known that thromboembolic events may occur fairly late in the postoperative course. However, the scientific knowledge on long-term prophylaxis is small and adequately performed studies must be done before general recommendations are made.

ISSN:1424-8832    

DOI:10.1159/000216906

出版商:S. Karger AG    

年代:1993

数据来源: Karger