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O D Ratnoff

Publications and source records attributed to O D Ratnoff.

At least 19 recordsLinked to original sources
PubMed2001

Confirmation of mendelian properties of heterodimeric fibrinogen molecules in a heterozygotic dysfibrinogenemia, "fibrinogen Amarillo," using gprphoresis to differentiate semifibrin molecules from fibrinogen and fibrin.

The fibrinogen molecule consists of two sets of Aalpha, Bbeta, and gamma chains assembled into a bilateral disulfide linked (Aalpha, Bbeta, gamma)2 structure. Cleavage of the two A-fibrinopeptides (FPA, Aalpha1-16) from normal Aalpha chains with arginine at position 16 (RFPA) by thrombin or the venom enzyme atroxin transforms fibrinogen into self-aggregating fibrin monomers (alpha, Bbeta, gamma)(2). Mutant Aalpha16R-->H fibrinopeptide (HFPA) cannot be cleaved from fibrinogen by atroxin. Many studies on heterozygous dysfibrinogenemias with this mutation suggested that incorporation of the mutant chains into the molecules was ordered in a manner yielding only (1) homodimeric normal (RFPARFPA) atroxin-coagulable molecules and (2) homodimeric abnormal (H(FPA)HFPA) atroxin-incoagulable molecules in equal quantities. Although heterodimeric molecules (RFPAHFPA) could not be found in studies on the intact protein, Meh et al. demonstrated their existence by showing that CNBr digests of fibrinogens from atroxin-treated Aalpha16R-->H heterozygotic dysfibrinogenemias consistently yielded N-terminal fragments (NDSKs) with partially resolved electrophoretic bands predominantly in between the NDSKs of fibrinogen and alpha-fibrin. An opportunity to confirm and better quantify the heterodimers arose with the recent development of a method (GPRphoresis) for identifying molecules lacking only one FPA, which is applied here in study of a newly presenting case of an Aalpha16R-->H dysfibrinogenemia, "fibrinogen Amarillo." GPRphoresis uses electrophoretic shifts, staged with GPRP-NH(2) to separate the self-aggregating fibrin monomers lacking both FPAs from weakly aggregating "semifibrin" molecules lacking one FPA An antifibrin alpha17-23 antibody is used to measure and differentiate the semifibrin from fibrinogen with FPA fully intact. Applying GPRphoresis to atroxin digests of fibrinogen Amarillo clearly demonstrated RFPARFPA, RFPAHFPA, and HFPAHFPA molecules in nearly perfect Mendelian 1:2:1 proportions. In turn, the high levels of the semifibrin in the terminal atroxin digests provide genetic phenotypic evidence supporting fidelity of the GPRphoresis method.

Dimerization↗
PubMed1995

Inhibition of expression of monocyte interleukin-1 by inhibitors of Hageman factor (factor XII).

In an earlier study, activated species of Hageman factor (factor XII) induced elaboration of interleukin-1 by human monocytes. These observations did not address whether Hageman factor participated in endotoxin-induced release of interleukin-1. To examine this question, the release of interleukin-1 by endotoxin-stimulated human mononuclear cells was measured in the presence of popcorn inhibitor, a specific inhibitor of Hageman factor. In the experiments herein described, popcorn inhibitor sharply decreased the release of interleukin-1 by human mononuclear cells that were incubated with endotoxin. This observation suggests that Hageman factor may play a role in the elaboration of interleukin-1 by human mononuclear cells. Conforming with this view, the addition of antiserum directed against Hageman factor inhibited the release of interleukin-1 from endotoxin-stimulated mononuclear cells.

Adult↗
PubMed1995

Inhibitory action of amyloid precursor protein against human Hageman factor (factor XII).

Amyloid precursor protein forms that contain Kunitz protease inhibitor domains are released from activated platelets, T-lymphocytes, and leukocytes and inhibit trypsin, plasmin, and activated factor XI. We investigated the effects of amyloid precursor protein isoforms on activated Hageman factor (factor XII), activated factor X (Stuart factor), and thrombin. Recombinant amyloid precursor proteins with or without the Kunitz domain, 770 and 695 amino acids, respectively, were produced in insect cells by Baculovirus expression (BAC770 and BAC695). Neither BAC695 nor BAC770 inhibited human alpha-thrombin or activated factor X. The partial thromboplastin time was prolonged by both amyloid precursor proteins, only one of which, BAC770, contains the Kunitz protease inhibitor domain. Both forms of amyloid precursor proteins inhibited ellagic acid-induced activation of Hageman factor but did not inhibit activated Hageman factor. Bismuth subgallate, which is an insoluble analog of ellagic acid, lost its ability to activate Hageman factor on being exposed to BAC770. Inhibition of ellagic acid-induced activation of Hageman factor by both forms of amyloid precursor protein was enhanced by heparin. These findings suggested that the heparin-binding domain of amyloid precursor proteins is not in the Kunitz domain. This heparin-binding domain may block the activation of Hageman factor by negatively charged agents. Thus, amyloid precursor proteins may be involved in the control of hemostasis, properties not all dependent on the Kunitz domain.

Amyloid beta-Protein Precursor↗
PubMed1994

Gene transfer in vivo: sustained expression and regulation of genes introduced into the liver by receptor-targeted uptake.

Receptor-mediated gene transfer has been used to introduce genes into tissues of animals in vivo. The genes introduced by this approach have been transiently expressed at low levels in animal tissues. High levels of expression, for longer periods, have been attained by the induction of cell division (i.e., partial hepatectomy) or disruption of lysosomal degradation of the DNA. We have studied the correlation of specific structural features on the DNA/ligand complexes with their ability to efficiently introduce DNA into the livers of intact animals. A chimeric gene containing the phosphoenolpyruvate carboxykinase gene promoter (nucleotides -460 to +73) linked to the structural gene for human factor IX (PEPCK-hFIX gene) was condensed with galactosylated poly(L-lysine) by titration with NaCl, resulting in complexes of defined size (10-12 nm in diameter) and shape. The PEPCK-hFIX gene complex was injected into the caudal vena cava of adult rats and the conjugated DNA was specifically targeted to the livers of the animals; no detectable DNA was noted in other tissues. The plasmid containing the PEPCK-hFIX gene was found as an episome in the livers of the rats 32 days after injection of the DNA complex. Human factor IX DNA, mRNA, and functional protein were detected up to 140 days after administration of the DNA complex (the duration of the experiment). Transcription from the PEPCK promoter could be induced over the entire course of the experiment by feeding the rats a high-protein, carbohydrate-free diet. We conclude that the structure of the DNA/ligand complexes is of key importance for the successful introduction of genes into the tissues of animals by receptor-mediated endocytosis.

Animals↗
PubMed1994

Familial Sneddon's syndrome: clinical, hematologic, and radiographic findings in two brothers.

We present the clinical, hematologic, and radiographic findings in two brothers with Sneddon's syndrome (stroke and livedo reticularis) and antiphospholipid antibodies. Patient 1 had anticardiolipin antibody and patient 2 had lupus anticoagulant, which we detected only upon repeated blood testing. One should test for both anticardiolipin antibody and lupus anticoagulant and repeat the screenings before determining a Sneddon's syndrome patient's antiphospholipid antibody status. Both Sneddon's syndrome and the primary antiphospholipid antibody syndrome are potentially familial causes of stroke. In familial cases, an inherited predisposition to antiphospholipid antibody production may be involved in disease pathogenesis.

Adult↗
PubMed1994

Airway obstruction in hemophilia (factor VIII deficiency): a 28-year institutional review.

Life-threatening airway compromise is rarely reported as a major complication of coagulation disorders. However, before adequate factor-replacement therapy became available, this complication was often fatal. A retrospective review of all patients with classic hemophilia admitted to our institution from 1964 through 1992 was performed. The records of 147 patients who had a total of 1804 admissions were examined. Fifteen episodes of airway obstruction occurred. Additionally, 6 cases of potential airway compromise and 5 cases of airway-endangering oropharyngeal bleeding were identified. Tracheotomy was performed in 5 patients; 1 fatality occurred before modern replacement products were available. Patients with this disorder have a 13% chance of some form of airway-endangering event with an 8% chance that it will be immediately life-threatening. Tracheotomy and subsequent decannulation are safe procedures in these patients.

Adolescent↗
PubMed1993

Inhibition of the activation of hageman factor (factor XII) by eosinophils and eosinophilic constituents.

Several syndromes characterized by striking eosinophilia may be complicated by thrombosis. The experiments described indicate that, paradoxically, eosinophils and certain of their constituents inhibit the activation of Hageman factor (HF, factor XII). In earlier studies, suspensions of mixed types of granulocytes, other nucleated peripheral blood cells, and platelets inhibited activation of Hageman factor by ellagic acid, glass, and sulfatides. After these cells were sedimented by centrifugation, the supernatant fluids were also inhibitory. No attempt had been made earlier to distinguish among different granulocytic species. In the present study, suspensions of eosinophils and the supernatant fluid after eosinophils had been separated by centrifugation inhibited activation of Hageman factor by ellagic acid. The protein concentration of that amount of supernatant fluid that inhibited activation by about half was 16 micrograms/ml, approximately the same as had been described for suspensions of peripheral blood mononuclear cells. Activation of Hageman factor by ellagic acid was also inhibited by certain constituents of eosinophils, including eosinophil peroxidase, eosinophil major basic protein and eosinophil cationic protein. Inhibition was not specific for ellagic acid-induced activation of Hageman factor, as inhibition was also observed with sulfatide-induced activation. Inhibition was presumably related to neutralization of the negative charge of activators of Hageman factor. Thus, bismuth subgallate, a particulate activator of Hageman factor, was no longer effective after it had been exposed to eosinophil cationic protein. The observations reported here raise the question of whether in vivo eosinophils modulate certain of the defense reactions ascribed to Hageman factor.

Blood Proteins↗
PubMed1993

Some complications of the therapy of hemorrhagic disorders.

The principal mode for treating disorders of hemostasis is correction of the patient's functional defect by transfusions of appropriate fractions of normal plasma or transfusions of platelets. Two major complications of such therapy are the transmission of infectious diseases, particularly hepatitis and the acquired immune deficiency syndrome (AIDS), and the development of antibodies against clotting factors that are deficient in the patient's plasma. Measures that reduce the occurrence of infection include careful selection of donors, fractionation of plasma with the help of monoclonal antibodies, and treatment of plasma or its fractions with heat or with virus-inactivating organic solvents. No technique of preparing or administering blood or its components can prevent the emergence of antibodies against clotting factors. Desensitization by repeated infusions of antigen, for example, antihemophilic factor, however, appears to result in remission in some patients.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Regulation of the phosphoenolpyruvate carboxykinase/human factor IX gene introduced into the livers of adult rats by receptor-mediated gene transfer.

Gene transfer systems targeting the asialoglycoprotein receptor have been developed to introduce functional genes into cells in culture and livers of intact animals. A synthetic neoglycoprotein carrier was constructed and complexed to a chimeric gene containing the cDNA for human factor IX ligated to the promoter-regulatory region of the gene for phosphoenolpyruvate carboxykinase from the rat. The complex was used to transfect human hepatoma cells that express the asialoglycoprotein receptor. Human factor IX DNA sequences were found in cells 10 days after treatment. A 1.4 kB mRNA transcript was detected by Northern blot hybridization, which was inducible by treatment with dexamethasone or cAMP with theophylline. Western blot hybridization of proteins secreted into the culture medium detected human factor IX. The chimeric gene was also transferred into livers of rats using the neoglycoprotein carrier system after partial hepatectomy. Although the results were variable, the exogenous gene was transcribed in livers of several animals, and maximal levels of expression of the fully processed human factor IX were detected 30 days after introduction. The concentration of factor IX in the blood returned to control levels 60 days after transfection. Factor IX production was induced as late as 96 days after treatment by feeding transfected animals a diet high in protein but devoid of carbohydrates. This DNA carrier system can be used to introduce functional genes into the livers of rats, and may be a useful technique for gene therapy targeting the liver.

Animals↗
PubMed1993

The effect of chemical modification of basic amino acid residues on the activation and amidolytic activity of Hageman factor (factor XII).

Modification of arginyl residues of Hageman factor by phenylglyoxal hydrate inhibits activation of this clotting factor in a plasma-free system, that is, in the absence of the other constituents of the contact activation system. Activation is also inhibited by alteration of the other two basic amino acid residues present, lysine and histidine. Chemical modification of histidine and arginine residues does not inhibit the amidolytic activity of activated Hageman factor. In contrast, modification of amino group(s) in N-terminal and lysine residues inhibits activated Hageman factor. Thus, basic amino acid residues essential to the activation or activity of Hageman factor appear to be variably accessible to chemical modification.

Amides↗
PubMed1993

An inhibitor of antihemophilic factor (factor VIII) in an 18-month-old nonhemophilic child.

PURPOSE: Inhibitors of factor VIII occur in < or = 20% of severely affected patients with classic hemophilia, but are unusual in nonhemophilic individuals, and have not been reported in very young children. We treated a child with a "high-responding" inhibitor. PATIENT AND METHODS: Our patient was an 18-month-old boy who had experienced several episodes of life-threatening hemorrhage. The techniques we used to decrease production of factor VIII in our patient were prolonged small doses of alternate day corticosteroids and continued administration of factor VIII. RESULTS: We controlled the acute bleeding with porcine factor VIII or with recombinant human factor VIIa (rFVIIa). Immune tolerance was successfully achieved using a combination of corticosteroids and daily factor VIII infusions. CONCLUSIONS: Multimodal therapy aimed at inducing long-term remission, along with stop-gap measures for hemostasis, may be effective for treating children with this acquired coagulopathy.

Animals↗
PubMed1992

Induction of expression of monocyte interleukin 1 by Hageman factor (factor XII).

The results reported here indicate that activated species of Hageman factor (HF, factor XII), a protein that mediates blood clotting, fibrinolysis, and activation of the complement cascade, induce elaboration of interleukin 1 (IL-1) by human monocytes. Augmentation of IL-1 production in mononuclear cell cultures was observed when HF was present along with lipopolysaccharide (LPS) but was not observed with HF alone. Furthermore, antiserum to HF abrogated the enhancement of IL-1 in cultures containing HF and LPS. Total IL-1 activity, which represents secreted and cell-associated IL-1, was enhanced in LPS-stimulated mononuclear cultures by HF. In the absence of LPS, the initial activation product of HF, HFa, which contains the serine protease enzyme activity and the surface-binding domains of the protein, induced IL-1 beta protein and mRNA. In the presence of LPS, the enzymatic moiety (HFf), which is also contained in HF and HFa, amplified IL-1 production. Induction and amplification of monocyte IL-1 by HF provides further evidence for establishing a role for HF in the acute-phase reaction and the cellular immune response.

Enzyme Activation↗
PubMed1992

Inhibition of the activation of Hageman factor (factor XII) by aprotinin (Trasylol)

Aprotinin (Trasylol; Bayer AG, Leverkusen, Germany), a protease inhibitor resembling or identical with Kunitz' pancreatic trypsin inhibitor, is said to have anticoagulant properties, but these are not clearly defined. The present study provides evidence that one action of aprotinin is inhibition of the activation of Hageman factor (factor XII).

Aprotinin↗
PubMed1992

Inhibition of the activation of Hageman factor (factor XII) by extracts of Schistosoma mansoni.

How intravascular helminth parasites evade host hemostatic defense mechanisms and survive within the circulating blood has not been adequately explained. Previous reports have described an inhibitor of the intrinsic clotting pathway in extracts of adult Schistosoma mansoni. Using a purified preparation of Hageman factor, we examined the ability of schistosome extracts and secretory products to inhibit the activation of human Hageman factor (factor XII) in an amidolytic assay. Both schistosome extracts and secretory products inhibited the activation of purified Hageman factor by more than 95%. Schistosome extracts inhibited activation of Hageman factor both by ellagic acid and by bovine sulfatides. In contrast, activated Hageman factor retained full activity in the presence of schistosome extracts as tested both on an amidolytic synthetic substrate and a natural substrate, plasma thromboplastin antecedent (factor XI). Our findings indicate that extracts and secretory products of adult Schistosoma mansoni contain a potent inhibitor of the activation of Hageman factor. Knowledge of a site at which schistosomes inhibit the intrinsic clotting pathway provides added insight into the mechanisms by which the parasites avoid the host hemostatic defense mechanisms.

Animals↗
PubMed1992

Some clotting factors in plasma during danazol therapy: free and total protein S, but not C4b-binding protein, are elevated by danazol therapy.

Anabolic steroids are known to increase the plasma concentrations of certain plasma proteins. In four patients given treatment with danazol, an attenuated androgen, the concentrations of heparin cofactor II, Hageman factor (factor XII), protein C, and both free and total protein S increased significantly when tested 39 to 103 days after the start of therapy. The titers of these proteins in samples obtained 21 days to 5 years after therapy was discontinued were similar to those before treatment, except for total protein S, the titer of which remained elevated. No significant changes in the titers of C4b binding protein or plasma plasmin inhibitory activity were found.

Adult↗