Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.6 (thromboplastin)
13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of hormonal contraceptive agents on the vascular system were studied in rats, dogs, and 34 women taking oral or injectable steroid contraceptive agents. Changes in the surface charge characteristics of the blood vessel wall and blood cells were observed. In dogs, the reduction in pore surface charge was greater in veins than in arteries. In rats, the induced mesenteric occlusion times were significantly reduced (p less than .001). However, Provera did not significantly reduce induced occlusion time in these animals (p greater than .01). Ov ral and Demulen lowered the mobilities of erythrocytes and platelets in women. Plasma coagulation times were not markedly altered in women receiving injectable progestin. Acitivated partial thromboplastin times were slightly decreased by Ovral and Demulen. The results suggest an increased tendency toward thrombosis in women taking steroid hormone contraceptive agents.
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PMID:Hormonal steroids: effects on the vascular system. 121

The effects of a contraceptive with a low estrogen content (Neogynon), the estrogen component (50 mcg ethinyl estradiol) and consecutively the gestagen component (250 mcg D-Norgestrel) of the contraceptive on blood coagulation and fibrinolysis were studied in 8 women. Each treatment cycle was followed by a control cylce. At various times of the control and therapy cycles coagulation and fibrinolytic parameters were investigated. Statistical analyses were performed using multivariate 2-factorial analysis of variance. Plasminogen exhibited a statistically significant increase during the treatment with ethinyl estradiol and the combination of this steroid with D-norgestrel. No significant changes were found for all other parameters, including partial thromboplastin time, fibrinogen, Factors X, IX, VIII, Factor VIII-related antigen, antithrombin III, and fibrin(ogen)degradation products.
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PMID:[Blood coagulation and fibrinolysis in women receiving estrogen, gestagen and estrogen-gestagen-contraceptives (author's transl)]. 127 96

The effect of 5 years' use of Norplant on blood clotting factors was assessed in 97 Singaporean women. The subjects were healthy, non-smoking non-alcohol drinking and non-lactating. Blood was sampled at 6, 12, 18, 24, 36, 48 and 60 months, after an overnight fast, and resting 30 minutes before venipuncture. Hemoglobin and hematocrit increased 10% in the 1st year (p0.001), fell for the next 2 years, reaching pre-insertion levels by 3 years, then increased 10% for the last 2 years. There was a significant shortening of the prothrombin time (PT) throughout the 5 years, and of activated partial thromboplastin time (APTT) for 3 years. Vitamin K-dependent Factors II, V, VII, decreased throughout the 5 years, and fibrinolytic activity decreased at 2 and 4 years of use. Fibrinogen increased at the end of the 1st year only. Platelet numbers rose 25.6% to 43.4%, and platelet aggregation to both ADP and collagen increased throughout the 5 year period. Alpha2-macroglobulin and antithrombin III antigen levels were heightened for 4 years. Most of the observed changes were different from those seen in oral contraceptive users, except for alterations in platelet function. While some of the measured clotting factors were significantly different, none were of any clinical significance, nor were these women in a state of hypercoagulation.
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PMID:Effect of long-term use of Norplant implants on haemostatic function. 138 Sep 4

Researchers from Gainesville, Florida compared data on 20 women who were randomly assigned the triphasic oral contraceptive (OC) Triphasil (ethinyl estradiol and levonorgestrel) with data on 24 women who were randomly assigned the triphasic OC Ortho-Novum (ethinyl estradiol and norethindrone) and data on 8 women who were controls to evaluate these 2 triphasic OCs' effects on coagulation and anticoagulation factors. They measured these factors at baseline and 6 and 12 months after beginning OC use. Both OCs significantly reduced prothrombin time (Triphasil at 6 and 12 months, p.001; Ortho-Novum at 6 months, p01, and at 12 months, p.001). They also decreased partial thromboplastin time (Triphasil at 6 months, p.01), and at 12 months, p.001; Ortho-Novum at 6 months, p.01). Both OCs significantly increased Factor XII after 6 and 12 months (Triphasil p.001 and p.01 for controls and p.05 from baseline, respectively; Ortho Novum p.01). Ortho-Novum considerably increased fibrinogen antigen at 6 and 12 months (p.05 and p.001 from baseline and p.05 for controls, respectively) while Triphasil increased it only at 12 months (p.05). Platelet counts remained the same. Ortho-Novum markedly increased antithrombin III activity after 6 months (p.05). Even though neither OC changed antithrombin III antigen, they did significantly increase alpha-1-antitrypsin antigen and plasminogen antigen and activity at 6 and 12 months as well as alpha-2-antiplasmin antigen at 12 months. Ortho-Novum increased alpha-s-antiplasmin antigen at 12 months. No great differences in coagulation or anticoagulation factors existed between the OCs. The mean values were within reference ranges. These results showed that the OCs had the same, limited effects on hemostasis and changes in coagulation factors offset changes in anticoagulation factors.
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PMID:Changes in coagulation and anticoagulation in women taking low-dose triphasic oral contraceptives: a controlled comparative 12-month clinical trial. 144 74

A longitudinal study of hemostatic function was carried out on 100 Singaporean acceptors using Norplant-2 rods for contraception. The results at the end of three years indicate a possible increased predisposition to thrombosis, as evidenced by significant increases in platelet count and aggregability. The prothrombin time (PT) and activated partial thromboplastin time (APTT) continued to remain shortened at the end of three years of use. There was also a general fall in most of the vitamin K coagulation factors. There is thus still an indication of a possible enhanced potential for hypercoagulation at the end of three years of Norplant-2 rod use.
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PMID:A three-year evaluation of hemostatic function in Singaporean Norplant-2 rod acceptors. 211 46

A longitudinal study of coagulation parameters was carried out on 100 Singaporean acceptors using Norplant for contraceptive purposes. At the end of 2 years of use, results from this ongoing study indicate that these acceptors continue to have an increased predisposition to thrombosis as evidenced by significant increases in platelet count and aggregability. The shortened but stable prothrombin time and activated partial thromboplastin time and increase in certain coagulation factors indicate that Norplant acceptors still have a possible potential for hypercoagulation at the end of two years of use.
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PMID:Two-year follow-up of changes in clinical chemistry in Singaporean Norplant acceptors: haemostatic changes. 249 88

The association between contraceptive agents and the risk of thromboembolism is known. Norplant is a relatively new subdermally implanted contraceptive delivery system, which releases a continuous low dose of the progestagen levonorgestrel over a period of 5 years or more. The present study examines 22 hemostatic parameters in 100 healthy, nonsmoking Singaporean women after 6 months and after 1 year of Norplant use. At the end of 1 year, there was a significant increase in platelet count and platelet aggregation, both of which indicate an increased risk of thrombosis. Prothrombin time and activated partial thromboplastin time were both significantly shortened, and Factor V and Factor X levels were elevated. These results indicate an increased potential for hypercoagulation. Mean values of hematocrit and hemoglobin were elevated. There was a decrease in the level of Factor VII and an increase in antithrombin III antigen level. It is intended that this longitudinal study be continued for the full 5 years, and it is suggested that similar studies be conducted in different populations.
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PMID:The effects of Norplant on clinical chemistry in Singaporean acceptors after 1 year of use: I. Haemostatic changes. 313 60

The effect of Norplant subdermal implants on 22 different hemostatic variables was determined in 100 women attending the Fertility Control Clinic of the Singapore National University Hospital before and after 6 and 12 months of use. The factors analyzed were: hematocrit, hemoglobin (Hb), prothrombin time (PT), activated partial thromboplastin time (APTT), platelet count, fibrinogen, coagulation factor II, Factor V,Factor VII, Factor VIII, Factor VIIIR:Ag, Factor X, plasminogen activator, FDP, plasminogen (imm), antithrombin III (functional), antithrombin (antigen), protein C, alpha2-antiplasmin, alpha2-macroglobulin, alpha2-antitrypsin, platelet count, platelet aggregation (ADP), and platelet aggregation (collagen). The factors that differed significantly after 12 months were: Hb,PT,APTT, Factors II,V,VII, and VIIIR:Ag, Plasminogen (imm), antithrombin III(antigen), alpha2-antiplasmin, platelet count, and platelet aggregation. Most of these differences, while significant, were still within the normal range, except for PT,APTT, and platelet count. The subjects were considered to be in an enhanced risk for hypercoagulation and thrombosis.
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PMID:The effects of Norplant-2 rods on clinical chemistry in Singaporean acceptors after 1 year of use: haemostatic changes. 314 69

The effect of Norplant, a subdermal contraceptive implant containing levonorgestrel, on blood coagulation factors was investigated in 47 healthy women. Coagulation parameters were also measured in 55 subjects who were taking combination type oral contraceptives (OCs) (either a pill containing 1 mg norethisterone and 50 mcg mestranol or a preparation containing 150 mcg levonorgestrel and 30 mcg ethinyl estradiol). Blood sampling was carried out at admission and after 1, 3, and 6 months of contraceptive use. Parameters measured included platelet count, prothrombin time, thrombin time, partial thromboplastin time with kaolin, clotting factors I, II, V, and VI-XIII, plasminogen, antithrombin III, alpha 1 antitrypsin, alpha 2 macroglobulin, and fibrinogen degradation products. Norplant users showed a lack of effect on the factors tested, except for factor VII activity, which was increased, and antithrombin III concentration, which was decreased after 3 months of use. In contrast, the combined OC users evidenced marked changes in platelet count, the screening tests, and most coagulation promoting factors. These changes became more pronounced after 6 months. Women taking the levonorgestrel-ethinyl estradiol OC evidenced less pronounced changes in some coagulation parameters than those taking the norethisterone-mestranol preparation; however, the high dropout rate among OC users limits the conclusions that can be drawn from these results. These results point to a relative lack of effect of Norplant implants on the blood coagulation-fibrinolytic system, presumably due to the absence of estrogen and the low dose of progestogen delivered to the body.
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PMID:Effect of levonorgestrel contraceptive implants, Norplant, on blood coagulation. 644 Jul 38

A case of a young women with paroxysmal nocturnal hemoglobin (PNH) who developed thrombosis of the cerebral veins after beginning a regimen of oral contraceptives is presented. She was 24 years old and presented with a 3-week history of frontal headache, neck stiffness, paraesthesiae of both arms, and weakness of the left leg. She had begun use of Microgynon 2 months before presentation, but had discontinued use when symptoms began. Hematological studies showed a shortened partial thromboplastin time, high fibrinogen and factor VIII levels, and prlonged euglobulin clot lysis time. Though this patient had a history of coagulation difficulties, it was not until after taking the estrogen-containing contraceptive preparation that PNH developed. The mechanism of thrombosis may be related to the liberation of thromboplastic material from hemolysed erythrocytes and to interaction between complement-sensitive platelets and complement components in plasma. It is suggested that the estrogen augmented the previously existing thrombotic condition in this patient, and that administration of estrogen-containing preparations should not occur in women with thrombotic disorders.
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PMID:Cerebral vein thrombosis and the contraceptive pill in paroxysmal nocturnal haemoglobinuria. 744 35


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