Severely impaired polymerization of recombinant fibrinogen gamma-364 Asp --> His, the substitution discovered in a heterozygous individual

During blood coagulation, soluble fibrinogen is converted to fibrin monomers that polymerize to form an insoluble clot. Polymerization has been described as a two-step process: the formation of double-stranded protofibrils and the subsequent lateral aggregation of protofibrils into fibers. Previous studies have shown that gamma chain residues Tyr-363 and Asp-364 have a significant role in polymerization, most likely in protofibril formation. To better define the role of these residues, we synthesized three fibrinogens with single substitutions at these two positions: Tyr-363 --> Ala, Asp-364 --> Ala, and Asp-364 --> His. We found that the release of fibrinopeptides A and B was the same for these variants and normal recombinant fibrinogen, showing that all variants had normal fibrin formation. In contrast, we found that polymerization was significantly delayed for both Ala variants and was almost nonexistent for the His variant. Clottability for the Ala variants was only slightly reduced, and fibrin gels were formed. Surprisingly, clottability of the His variant was substantially reduced, and fibrin gels were not formed. Our data suggest that both protofibril formation and lateral aggregation were altered by these substitutions, indicating that the C-terminal domain of the gamma chain has a role in both polymerization steps.     

The analgesic effect of PCA buprenorphine in Taiwan''s gynecologic patients

Bloodless cardiac surgery would be optimal for all patients undergoing major or complex heart surgery; however, for Jehovah's Witnesses it involves a religious law and is fundamentally mandated. In this context, we review a case of unstable angina with associated anemia requiring catheterization and definitive intervention in a Jehovah's Witness patient. Coronary stenting to stabilize the acute coronary syndrome is described with definitive total revascularization performed by coronary artery bypass graft surgery after utilizing erythropoietin and aggressive blood conservation techniques.     

Spermine-mediated phosphorylation of RNA polymerase I and its effect on transcription

A nuclear protein kinase, designated NII, was purified essentially to homogeneity from the Morris hepatoma 3924A. In the presence of excess Mg2+, phosphorylation of casein by the kinase was stimulated by spermine (1-5 mM) and was inhibited completely by 0.1 microgram/ml heparin. The apparent Km for casein was reduced in the presence of spermine. Spermine preferentially augmented phosphorylation of threonine residues. The kinase was also associated with highly purified RNA polymerase I and appears to correspond to two polypeptides (Mr 42,000 and 24,600) of the polymerase. RNA polymerase I polypeptides of Mr 120,000 (S2), Mr 65,000 (S3) and Mr 24,600 (S5) were phosphorylated by the endogenous kinase. Spermine enhanced phosphorylation of the RNA polymerase I subunits as much as 20-fold. Phosphorylation activated RNA polymerase I; the phosphorylated enzyme synthesized longer product with no apparent effect on the number of RNA chains initiated.