Undetectable plasma L-arginine level before visible hemolysis in thrombotic thrombocytopenic purpura.
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Aged↗
Biomedical subjects
D K Liles
Publications and source records attributed to D K Liles.
Successful treatment of transient acquired factor X deficiency by plasmapheresis with concomitant intravenous immunoglobulin and steroid therapy.
Two patients with no history of previous bleeding diatheses presented with active bleeding from multiple body sites, declining hemoglobin levels, and markedly prolonged prothrombin times (PT) and activated partial thromboplastin times (aPTT) with incomplete correction on PT mix assays. Both patients demonstrated a severe deficiency of factor X (F.X) (<1%; reference range 60-150%). F.X levels and bleeding were refractory to multiple transfusions of fresh frozen plasma (FFP) in both patients. In contrast, daily therapeutic plasma exchange (PLEX) with concomitant administration of intravenous immunoglobulin (IV IgG) and steroids produced a rapid increase in F.X levels with cessation of bleeding, followed by stabilization and normalization of F.X levels and progressive correction of coagulation times. Neither patient has demonstrated a recurrence of the bleeding tendency following discontinuation of steroid therapy. These patients had transient acquired F.X deficiency, a rare coagulopathy, which can result in a lethal bleeding diathesis. An IgG inhibitor that selectively inhibited F.X activation in Russell's viper venom or tissue factor/F.VIIa assays was demonstrated in one patient's pretreatment plasma. Previous treatment of hemorrhage in transient acquired F.X deficiency has been prothrombin complex and/or activated clotting concentrates, which can be associated with transient hypercoagulable states. This is the first reported use of PLEX in transient acquired F.X deficiency. PLEX is safe, efficacious, and rapidly restores hemostasis in this rare acquired bleeding disorder.
Adult↗
Mammalian recombinant coagulation proteins: structure and function.
Recombinant DNA technology has permitted the production of synthetic proteins which are potentially free of human infectious agents. Despite production in foreign cells, these proteins are structurally and functionally comparable to the native proteins. Recombinant clotting factors VIII, IX, VIIa, and von Willebrand factor have the same primary sequence as their plasma counterparts. The secondary and tertiary structures are similar, Post-translational modifications, including proteolytic processing, disulfide bonding, addition and processing of N- and O-linked glycans, gamma-carboxylation of glutamic acid residues, beta-hydroxylation of aspartic acid residues, sulfation of tyrosine residues, and phosphorylation of serine residues, are similar but not always identical, In some instances. these differences may cause significant functional differences. For example, reduced tyrosine sulfation and serine phosphorylation of recombinant factor IX have been correlated with reduced recovery following intravenous infusion. The specific clotting activity of the recombinant factors, an indication of their coagulant function, is equivalent to that of the plasma factors. Finally, these proteins have been used clinically and shown to correct clinical deficiencies of these proteins in a manner that is similar to replacement with plasma factors. All in all, the promise of recombinant DNA technology for coagulation and other disorders remains bright.
Animals↗
Cloning, expression, and characterization of mouse tissue factor pathway inhibitor (TFPI).
Tissue factor pathway inhibitor (TFPI) acts to regulate the initiation of coagulation by first inhibiting factor Xa. The complex of factor Xa/TFPI then inhibits the factor VIIa/tissue factor complex. The cDNA sequences of TFPI from several different species have been previously reported. A high level of similarity is present among TFPIs at the molecular level (DNA and protein sequences) as well as in biochemical function (inhibition of factor Xa, VIIa/tissue factor). In this report, we used a PCR-based screening method to clone cDNA for full length TFPI from a mouse macrophage cDNA library. Both cDNA and predicted protein sequences show significant homology to the other reported TFPI sequences, especially to that of rat. Mouse TFPI has a signal peptide of 28 amino acid residues followed by the mature protein (in which the signal peptide is removed) which has 278 amino acid residues. Mouse TFPI, like that of other species, consists of three tandem Kunitz type domains. Recombinant mouse TFPI was expressed in the human kidney cell line 293 and purified for functional assays. When using human clotting factors to investigate the inhibition spectrum of mouse TFPI, it was shown that, in addition to human factor Xa, mouse TFPI inhibits human factors VIIa, IXa, as well as factor XIa. Cloning and expression of the mouse TFPI gene will offer useful information and material for coagulation studies performed in a mouse model system.
Amino Acid Sequence↗
Needle aspiration for diagnosis of cellulitis.
Diagnosing the causative agent of bacterial cellulitis is difficult. Blood culturing and needle aspiration have been used: the former has an extremely low sensitivity, the yield of the latter ranges from 4 to 42 percent. A retrospective study was conducted to determine the diagnostic success of needle aspiration and culture of the leading edge of cellulitis with a 21 to 22 gauge syringe and conventional bacteriologic culture of blood in determining the agent that causes acute cellulitis. This agent was determined in 33 percent of patients by needle aspiration and in 4 percent using blood cultures.
Bacteria↗