A second mutation in the methylenetetrahydrofolate reductase gene and the risk of venous thrombotic disease.

We assessed the effect of a recently described mutation in the MTHFR gene (1298 A --> C) on the risk of deep venous thrombosis (DVT) by determining its prevalence in 190 patients with verified DVT and in age-, race- and gender-matched controls. MTHFR 1298 A --> C was found in 42.1% of patients and in 41.1% of controls. The OR for venous thrombosis was 1.07 (95% CI 0.70-1.65) for heterozygotes and 0.83 (95% CI 0.33-2.08) for homozygotes. The OR for the factor V Leiden (FVL) mutation was 3.40 (95% CI 1.22-9.48), for FII 20210 G --> A was 5.22 (95% CI 1.12-24.2) and for MTHFR 677 C --> T, 1.24 (95% CI 0.82-1.87). No significant increased risk for venous thrombosis was found when MTHFR 1298 A --> C was coinherited with FVL (OR 2.85, 95% CI 0.88-9.23), FII 20210 G --> A (OR 7.19, 95% CI 0.87-59.4) or MTHFR 677 C --> T (OR 1.44, 95% CI 0.71-2.92). These data do not support a critical role of MTHFR 1298 A --> C in the predisposition to DVT.

Factor V Arg306-->Thr (factor V Cambridge) and factor V Arg306-->Gly mutations in venous thrombotic disease.

We investigated the prevalence of two reported mutations of the factor V gene (factor V Arg306-->Thr, or factor V Cambridge, and factor V Arg306-->Gly) in 104 relatively young patients with verified venous thrombosis and in 208 age-, sex- and race-matched controls, in order to establish whether the two mutations are associated with increased predisposition for venous thrombosis. PCR amplification followed by BstNI and MspI digestion was employed to determine the genotypes, and each mutation was confirmed by DNA sequencing. Among the controls, one individual was found to be heterozygous for the factor V Arg306-->Thr mutation and one heterozygous for the factor VArg306-->Gly mutation; none of the patients carried either mutation. Our findings do not support factor V Cambridge and factor V Arg306-->Gly as risk factors for venous thrombosis.

Use of fibrin glue derived from snake venom in testicular biopsy of rams

Sequelae due to testicular biopsy such as hemorrhage, adhesion and fibrosis may be limiting factors to the use of this surgical procedure. Fibrin glue (FG) derived from snake venom was used to minimize these sequelae, as well as to evaluate its healing property in tunica vaginalis and scrotal skin or rams. Applicability of fibrin glue derived from snake venom was tested in different tissues of other animals such as in sciatic nerve and colon of rats and skin of rabbits. In the present study, 30 healthy adult rams were used. They were divided into 3 groups of 10 animals each as follows: G1: fibrin glue group (application of fibrin glue on puncutre sites and skin incisions after bilateral testicular biopsy with a Tru-Cut needle); G2: swab/nylon group (hemostasis by compression with a swab on puncture sites and skin suturing with nylon after biopsy) and G3: control group (the animals were not subjected either to biopsy or to surgery). On the 20th day after biopsy, the presence of adhesion strands between the sites of skin incision and testicle was evaluated by palpation. Adhecion strands were found in three testicles (15 per cent) in G1 and in two testicles (10 per cent) in G2. One hundred days after biopsy, orchiectomy was carried out and the material collected was assessed for subcutaneous (SC) and/or tunica vaginalis adhesions. G3 did not present any abnormality. Groups G1 and G2 presented four testicles each (20 per cent) with adhesion between the tunics and biopsy site. On the other hand, subcutaneous adhesions were found once (5 per cent) in G1 and three times (15 per cent) in G2. Fibrin glue showed to be of easy application, required short postoperative monitoring, presented fast and good-quality healing property and tended to reduce formation of subcutaneous adhesion.

Ausência de ação antitrombótica em trombose venosa experimental / Absence of antithrombotic effect of metronidazolin experimental venous thrombosis

Com base na utilização empírica do metronidazol no tratamento de picada de cobra e em uma possível ação fibrinolítica, alguns médicos brasileiros o usaram no tratamento de trombose venosa profunda, embora não existam estudos que justifiquem tal emprego. OBJETIVO: Verificar possível existência de efeito antitrombótico do metronidazol em modelo de trombose induzida na veia cava de ratos e uma eventual ação anticoagulante ou fibrinolítica dessa droga. MÉTODO: 71 ratos da raça Wistar foram usados em 4 experimentos. No primeiro, 29 animais foram divididos em três grupos: controle (solução salina), heparina (200UI/kg) e metronidazol (6mg/kg). 10 minutos após a injeção IV a trombose foi induzida pela ligadura da veia cava, distalmente à veia renal esquerda. Três horas depois, a veia cava era removida e aberta, e o trombo, se presente, retirado para pesagem, sendo o sangue do animal retirado para medida do TTPA, TT e TP. No segundo experimento, o sangue foi retirado dos animais (n=18) 10 minutos após a injeção das drogas, para medida dos mesmos parâmetros. No terceiro experimento os animais (n=22) foram injetados com metronidazol ou salina e o tempo de lise de euglobulina medido 3 horas após. No quarto experimento, 22 animais foram sorteados para um de dois grupos: controle, com injeção IV de 12ml de salina ou metronidazol, (12mg/kg), sendo a trombose induzida 10 minutos após. RESULTADOS: Não houve diferença entre os grupos controles e os grupod tratados com metronidazol, em relação à incidência e peso dos trombos e com relação aos parâmetros hemostáticos estudados. Nos animais tratados com heparina não houve formção de trombos, havendo aumento de TTPA e de TT aos 10 minutos, e de TT, após 3 horas. CONCLUSÄO: No modelo experimental empregado, o metronidazol não mostrou efeito antitrombótico e também ação sobre o parâmetros hemostáticos estudados, sugerindo que o uso clínico dessa droga no tratamento de trombose venosa é duvidoso, a menos que outros estudos venham demosntrar algum efeito benéfico.

Reparation of peripheral nerves with fibrin glue prepared from snake venom. Preliminary results.

A new fibrin glue obtained from snake venom is presented, with possible utilization in various fields of medicine. The preparation procedures and tests in the reparation of peripheral nerves are described. The preliminary results were similar to the conventional fibrin glue procedure.

Evaluation of platelet number and function and fibrinogen level in patients bitten by snakes of the Bothrops genus.

Platelet function and plasma fibrinogen levels were evaluated in 14 patients, 10 males and 4 females, aged 13-59 years bitten by Bothrops genus snakes. There was a statistical difference (p < 0.05) among plasma fibrinogen levels evaluated 24 and 48 hours after envenomation. There was a tendency towards normalization after 48 hours of treatment. The low platelet number was clear in 24-48 hour evaluations with a tendency towards normalization after 48 hours of treatment (p < 0.05). When platelet function was stimulated by collagen and epinephrine, it appeared to be within normal values. On the other hand, when it was stimulated by adenosine diphosphate (ADP), platelet function was hypoaggregated by a single micromol concentration until 48 hours after treatment. At a 3 micromol concentration, there were alterations only before specific treatment (p < 0.05). Fibrinogen levels and fibrin degradation product (FDP) levels appeared to be altered in 83.33% of patients evaluated. The authors suggest that platelet hypoaggregation is related to decreased fibrinogen and increased FDP levels.

Platelet activation following application of an Esmarch bandage and tourniquet in rabbits.

The present study evaluates platelet activation following application of an Esmarch bandage and a tourniquet, procedures commonly employed to provide a bloodless operative field during limb surgery. Platelet aggregation was increased in blood samples taken from rabbits 60 min after an Esmarch bandage was applied to one thigh and immediately released. When this treatment was combined with the application of a tourniquet for 60 min, a procedure which alone did not affect platelet aggregation, results were similar to those obtained following the Esmarch bandage alone. These data suggest that tissue compression produced by application of an Esmarch bandage, but not the ischemia derived from the tourniquet, produced platelet aggregation.

Platelet activation following application of an esmarch bandage and tourniquet in rabbits

The present study evaluates platelet activation following application of an Esmarch bandage and a tourniquet, procedures commonly employed to provide a bloodless operative field during limb surgery. Platelet aggregation was increased in blood samples taken from rabbits 60 min after an Esmarch bandage was applied to one thigh and immediately released. When this treatment was combined with the application of a tourniquet for 60 min, a procedure which alone did not affect platelet aggregation, results were similar to those obtained following the Esmarch bandage alone. These data suggest that tissue compression produced by application of an Esmarch bandage, but not the ischemia derived from the tourniquet, produced platelet aggregation

Platelet activation in experimental arterial thrombosis.

Platelet aggregates were studied in dogs with induced arterial thrombosis, by the method of Wu and Hoak. Blood was withdrawn from a jugular vein and from the femoral vein on the operated side 24 h after thrombus induction and immediately and 2 h after blood flow was restored by thrombectomy. Platelet activation was significant in dogs with obstructive arterial thrombosis and which tended to subside after thrombectomy. Activation or formation of platelet aggregates seemed to occur in the ischemic limb. It is suggested that this experimental model could be useful to test the action of anti-platelet drugs in vivo.