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Biomedical subjects

A L Bloom

Publications and source records attributed to A L Bloom.

At least 109 records · Page 6Linked to original sources
PubMed1976

The dissociation of factor VIII by reducing agents, high salt concentration and affinity chromatography.

Incubation of a factor VIII-rich fraction of plasma with a high concentration of salt confirmed the production of both high (HMW) and low (LMW) molecular weight factor VIII clotting activity (FVIIIC) as determined by agarose gel filtration but with considerable overlap. The electrophoretic mobility of factor VIII related protein (FVIIIRP) detected by precipitating rabbit antiserum was not affected by this treatment and LMW FVIIIC devoid of FVIIIRP was apparently produced. At low concentration the reducing agent dithiothreitol (DTT) altered the electrophoretic mobility of FVIIIRP. At higher concentrations it altered both its mobility and antigenicity and an LMW FVIIIRP was produced. Contrary to the findings of other workers no LMW FVIIIC devoid of FVIIIRP was produced. In further studies factor VIII-rich plasma fraction was treated with sepharose beads to which had been coupled a non-coagulation inhibitory precipitating rabbit antibody to FVIIIRP. Both FVIIIRP and FVIIIC were taken up by the beads but after elution with 1.5 M NaCl, FVIIIC of LMW and devoid of FVIIIRP was selectively removed. Antisera raised to LMW FVIIIC produced with 1.5 M NaCl either by the gel filtration or affinity chromatography methods inhibited FVIIIC and precipitated with HMW factor VIII-rich fractions. The results were consistent with the possibility that factor VIII clotting activity and FVIIIRP exist in plasma as a non-covalently bound complex.

Antigens↗
PubMed1975

Vitamin E deficiency and platelet functional defect in a jaundiced infant.

A 16-month-old infant with hepatic fibrosis, cholestasis, and chronic jaundice had signs of vitamin E deficiency, including mild acanthocytosis, thrombocytosis, increased peroxide haemolysis, and absent serum vitamin E. Abormal prothrombin consumption and platelet restocetin aggregation suggested the presence of defective platelet function, and correction studies indicated that this was due to a plasma defect. The abnormality was corrected by treatment with vitamin E, and the findings suggest a possible role of this vitamin in platelet reactions.

Blood Platelet Disorders↗
PubMed1975

Postoperative problems and management after hepatic resection for blunt injury to the liver.

The postoperative problems and management of 8 patients following right hepatic lobectomy for blunt liver injury are discussed. Multiple injury and in particular chest injury are of importance. Respiratory distress may be insidious in onset and must be anticipated. Most patients require at least temporary positive pressure ventilation. Liver regeneration is rapid and histological evidence of regenerative hyperplasia is present within 3 days of injury. Hypoglycaemia of a degree sufficient to threaten life may occur postoperatively, particularly in the first 48 hours. Jaundice may be a worrying postoperative feature, but the use of T-tube drainage after hepatic lobectomy will enable any possible extrahepatic obstruction to be excluded. Hypoproteinaemia and hypo-albuminaemia occur in the immediate postoperative period, and recovery rapidly follows the peak period of regenerative activity of the liver. Normal levels are regained by the fourth to sixth postoperative weeks. Prophylactic antibiotics have no place in the postoperative management of blunt liver injury. Haemorrhagic diathesis is common after hepatic resection and is of a complex nature. Intravascular coagulation may occur and factor V deficiency is common. The mainstay of treatment is transfusion of fresh blood.

Abdominal Injuries↗
PubMed1975

The immunological localization of factor V in human tissue.

Antibody to factor V was produced by immunizing rabbits with purified factor V from human plasma. Various tissues were examined for the presence of factor-V antigen using this antiserum. It was consistently demonstrated in homogenates of liver and spleen by means of an antibody (coagulation inhibitor) neutralization technique. The antigen was further localized histologically by the indirect fluorescent antiglobulin technique. It was present on the endothelium of normal blood vessels in all organs examined. In the liver it was detected in hepatic parenchymal cells and a distinctive pattern of fluorescence in the spleen suggested that it was being detected on platelets. Results were negative in all other tissues examined. The findings confirm the presence of factor V in hepatic parenchymal cells and support the suggestion that endothelial coagulation factors may play a role in haemostasis and thrombosis.

Animals↗
PubMed1975

Factor-V activation by thrombin and its role in prothrombin conversion.

Purified coagulation factors and specific antibodies to factor V and factor X were used to investigate the action of thrombin on factor V and the mechanism by which thrombin-treated factor V influences prothrombin activation. The formation of a complex or complexes between phospholipid, factor V, factor Xa and calcium was demonstrated by column chromatography on Sephadex gel, and by immunological analysis of the column fractions including the use of solid-phase antibodies. Kinetic experiments demonstrated that generation of thrombin from purified prothrombin was accomplished by this complex. Pre-treatment of factor V with trace quantities of thrombin resulted in increased yield and rate of thrombin generation. It was shown that phospholipid became saturated when incubated with increasing concentrations of factor V and that the initial saturating concentration of the latter was reduced by pre-treatment with thrombin. The findings confirm that optimum conversion of prothrombin to thrombin is accomplished by a complex or complexes of phospholipid, factor V, factor Xa and calcium and it is suggested that thrombin plays an autocatalytic role in these reactions.

Animals↗
PubMed1975

The localization of factor V within normal human platelets and the demonstration of a platelet-factor V antigen in congenital factor V deficiency.

Separation of human platelets from plasma by a modified gel-filtration technique reveals very low levels of factor-V activity of the platelet suspension. Repeated freezing and thawing increases the factor-V activity in various factor-V assays. This activity neutralized the inactivating effect of a rabbit-antihuman factor V antibody to plasma factor V, while intact platelets had almost no such capacity. Washed and normal platelets and gel filtered platelets showed marked positive fluorescence after treatment with antifactor V serum and FITC labelled sheep antirabbit immunoglobulin. Fluorescence was inhibited by previous incubation of the antifactor V serum and platelet lysates. Platelets of a factor V deficient patient showed the same fluorescence pattern as normal platelets indicating that they contained a factor V antigen. These platelets showed after lysis no effect in various factor V assays. From these studies it is concluded that the localization of factor V is within the platelets.

Antigens↗