Biomedical subjects

D L Amrani

Publications and source records attributed to D L Amrani.

39 records · Page 3Linked to original sources

PubMed1976

Studies on the structural abnormality of fibrinogen Paris I.

The structural properties of an inherited fibrinogen abnormality designated fibrinogen Paris I were investigated. Dodecyl sulfate gel electrophoresis of unreduced samples revealed no discernible differences in molecular weight from normal; this implied that in fibrinogen Paris I, the normal fibrinogen architecture of six covalently linked chains per molecule is preserved. Examination of dithiothreitol reduced samples before and after treatment with Reptilase or thrombin revealed that the Aalpha- and Bbeta-chains could release the A and B peptides, respectively. A mutant chain (mol wt 52,500, termed gammaParis I) which replaces a large proportion of gamma-chains (mol wt 49,400) was shown, like normal gamma-chains, to lack thrombin- and Reptilase-sensitive sites. The gamma-chains and alpha-chains of Paris I fibrin underwent Factor XIIIa-catalyzed cross-linking slowly; this behavior was not attributable to an intrinsic abnormality of these chains themselves but rather to the inhibitory effect of the mutant gammaParis I chains on this process. Results of DEAE-cellulose gradient elution chromatography of Paris I fibrinogen preparations revealed the presence of small amounts of normal fibrinogen molecules and also indicated that the gammaParis I chains possessed structural overlap with gamma-chains. Unlike gamma-chains however, the gammaParis I chains did not incorporate dansylcadaverine in the prescence of Factor XIIIa, nor, as previously reported, did they undergo cross-linking. The observations indicate that the amine acceptor site found in the COOH-terminal region of the gamma-chain is either not present on the gammaParis I chain or is unavailable for cross-linking. Further support for localization of the abnormality in the COOH-terminal region of the molecule was obtained from the observation that during plasmic hydrolysis of Paris I fibrinogen, at least one unique form of core Fragment D (DParis I) was evolved, whereas Fragment E did not differ from normal.

Amines↗

PubMedDate not supplied

Evaluation of factor VIII-rich cryoprecipitate and the plasma fibronectin-rich, heparin-precipitable fraction prepared from single-donor plasma units.

A plasma fibronectin-rich component was prepared by heparin-induced 4 degrees C precipitation of fresh or stored (21 days at 4 degrees C), single-donor plasma. The recovery of plasma fibronectin was 45 percent at a concentration of 0.05 mg heparin per ml (7.5 units/ml) and 75 percent at 0.1 mg per ml (15 units/ml). The biologic activity of plasma fibronectin, as assessed by the spreading of Chinese hamster ovary cells or attachment of monocytes to gelatin-coated surfaces, was similar to that of plasma fibronectin concentrates made from fresh or stored plasma. Only 20 to 30 percent of the factor VIII activity in fresh plasma was recovered in cryoprecipitate produced after the heparin-induced precipitate containing fibronectin was removed. Cryoprecipitate prepared from the supernatant plasma that remains after heparin-induced cold precipitation in the presence of CaCl2 (5 mM) contained approximately 50 percent less factor VIII. The relatively low recovery of factor VIII in cryoprecipitate prepared from fibronectin-depleted plasma makes cryoprecipitation an unsuitable method of producing fibronectin-rich and factor VIII-rich components effectively from a single unit of fresh plasma. However, heparin-induced cold precipitation provides an efficient method for preparing plasma fibronectin concentrates from small plasma pools or single units of stored or fresh plasma.

Blood Preservation↗

PubMedDate not supplied

Hemostatic evaluation of Sarns/3M-VAD implantation in calves.

The authors evaluated the potential for thrombotic complications arising from implantation of a ventricular assist device (Sarns/3M-VAD) in four calves. Coagulation screening tests (prothrombin time [PT], partial thromboplastin time [PTT], thrombin time [TT]), fibrinogen levels, and antithrombin III functional activity were found to be of little value as predictors of the degree of activation of the hemostatic system. However, platelet counts, adenosine diphosphate (ADP)- and collagen-induced platelet aggregation, and thromboxane (TXB2) levels were good indicators of changes in platelet reactivity. Platelet counts (initial value 6 x 10(5) rose, and were associated with increased rate and extent of ADP- and collagen-induced platelet aggregation, which remained elevated during the entire 25 day postimplantation period. The first 5 days postimplantation revealed a typical acute inflammatory response, with increased platelet levels, but with TXB2 levels significantly decreased during this period. A monoclonal antibody based bovine D-dimer assay and Western blot studies indicated a small but significant increase in circulating bovine D-dimer, indicating localized fibrin formation and its dissolution.

Animals↗