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Biomedical subjects

R I Handin

Publications and source records attributed to R I Handin.

At least 91 records · Page 5Linked to original sources
PubMed1978

Elevation of platelet factor four in acute myocardial infarction: measurement by radioimmunoassay.

A radioimmunoassay has been developed for the measurement of PF-4--a chemically well-defined heparin-neutralizing molecule. PF-4 was iodinated, repurified by affinity chromatography on heparin-Sepharose, and incubated with rabbit antiserum and a source of unlabeled antigen. Following incubation at 4 degrees C for 24 hr, bound PF-4 was precipitated with 2.2M ammonium sulfate. The assay, which could detect 25 pg of purified PF-4, was unaffected by the presence of plasma containing up to 50 U/ml heparin. The plasma concentration of PF-4 in 30 normal subjects was 16 +/- 4 ng/ml. This level was increased in patients with pulmonary emboli, prosthetic cardiac valves, and severe cardiorespiratory failure. In addition, 21 of 50 patients admitted to the hospital with acute chest pain who had sustained a myocardial infarct had a mean level of 95 ng/ml. In contrast, the mean level in 21 patients with chest pain but without evidence of infarction was 29 ng/ml. PF-4 remained elevated for at least 1 week after infarction in six of the eight patients studied and then returned to within the normal range. The data suggest that radioimmunoassay of PF-4 may be a useful test to measure activation of the coagulation system and an aid to the diagnosis and treatment of patients with thromboembolic disorders.

Acute Disease↗
PubMed1977

The effects of "anti-platelet" drugs on bleeding time and platelet aggregation in normal human subjects.

The effects on hemostasis of several commonly used drugs previously described as inhibiting platelet function were evaluated in a randomized, double-blind study of 54 normal volunteers. The subjects were each given a single dose of aspirin, chlorpromazine, glyceryl guaiacolate, diphenhydramine, indomethacin or lactose placebo. A single dose of aspirin significantly prolonged the template bleeding time and inhibited secondary platelet aggregation two and 24 hours after ingestion. Single doses of indomethacin and chlorpromazine affected aggregation at two hours but had no effect on bleeding time, although multiple doses of indomethacin did prolong bleeding time. Glyceryl guaiacolate inhibited aggregation one hour after ingestion but had no effect on bleeding time. Diphenhydramine did not affect either. These findings suggest that standard doses of many commonly used "anti-platelet" drugs may have little clinical effect on the hemostatic mechanism in normal man. Results of in-vitro platelet-drug incubations may not be directly applicable to in-vivo hemostasis.

Aspirin↗
PubMed1977

Enhancement of platelet function by superoxide anion.

During the aerobic conversion of xanthine to uric acid by xanthine oxidase, superoxide anion and hydrogen peroxide are produced along with the hydroxyl radical. Our studies demonstrate that washed human platelets incubated with xanthine and xanthine oxidase aggregated and released [14C]serotonin. Aggregation and release were dependent on the duration of exposure to xanthine oxidase as well as the concentration of enzyme. Both reactions were inhibited by the superoxide scavenger enzyme superoxide dismutase but not by catalase, or the free radical scavenger mannitol, suggesting that they were induced by superoxide anion. Superoxide-dependent release was inhibited by prior incubation of platelets with 1 mM EDTA, 1 micronM prostaglandin E1, or 1 mM dibutyryl cyclic AMP, but was unaffected by 1 mM acetylsalicylic acid or 1 micronM indomethacin. After prolonged incubation with xanthine and xanthine oxidase there was also efflux of up to 15% of intraplatelet 51Cr, a cytosol marker. This leakage was prevented by the addition of catalase to the media but not by superoxide dismutase. Incubation with xanthine and xanthine oxidase did not produce malonyldialdehyde, the three-carbon fatty acid fragment produced during prostaglandin endoperoxide synthesis and lipid peroxidation. Prior exposure of platelets to low fluxes of superoxide anion lowered the threshold for release by subsequent addition of thrombin, suggesting a synergistic effect. We conclude that superoxide-dependent aggregation and release may be a physiologically important method to modulate hemostatic reactions particularly in areas of inflammation or vessel injury which could have high local concentrations of superoxide anion.

Blood Platelets↗
PubMed1976

Purification and binding properties of human platelet factor four.

Methods are described for the purification of a heparin-neutralizing protein from human platelets. The protein, obtained by conventional or affinity chromatographic techniques, is homogeneous by disc and sodium dodecyl sulfate gel electrophoresis, immunoelectrophoresis, and gel electrofocusing and can be obtained in a final yield of 75%. The protein has a subunit molecular weight of 9600, an isoelectric point at pH 7.6, and 18% basic and 22% acidic amino acid residues. The purified heparin-neutralizing protein forms dissociable complexes with heparin as measured by electrophoretic and Millipore filtration techniques employing [3H]heparin. The ability of a series of sulfated glycosaminoglycans to displace [3H]heparin from the binding protein was compared. The mole ratios required were: heparin less than heparan sulfate less than dermatan sulfate less than chondroitin 6-sulfate less than chondroitin 4-sulfate. Although the degree of sulfation of the aminoglycans correlated with the ability to displace [3H]heparin, the conformation fo the carboxyl group of the uronic acid and the location of the sulfate groups on the amino sugar also influenced the affinity for the protein. Evidence is also presented that binding to aminoglycans occurs via ionic interactions between lysine residues on the protein and negatively charged groups on the aminoglycan. Chemical modification of lysines by guanidination decreased heparin-neutralizing and binding activity, while modification of arginine residues had no effect. Heparin could prevent lysine modification when specifically bound to the heparin-neutralizing protein, but did not prevent lysine modification of other proteins.

Amino Acids↗
PubMed1976

Antibody-induced von Willebrand's disease: a newly defined inhibitor syndrome.

A patient is described with clinical and laboratory evidence of von Willebrand's disease (VWD) in association with lymphosarcoma. He consistently had a bleeding time of over 20 min; factor VIIAHF, VIIAGN, and VIIVWF under 20%; and severe, diffuse hemorrhage, Following transfusion with cryoprecipitate, the patient had the expected rise in VIIAGN and VIIAHF. The patient's plasma contained an inhibitor which prevented aggregation of normal platelets by ristocetin, but which did not interfere with the measurement of VIIAGN or inactivate VIIAHF activity. The inhibitor was present in serum heated at 56 degrees C for 30 min, was present in a purified IgG fraction of serum, and was precipitated by anti-human IgG. The antibody did not interact directly with washed platelets, but appeared to interact with that portion of the factor VII protein that supports ristocetin aggregation (VIIIVWF). The data provide the first explanation for the pathophysiology of the acquired von Willebrand's syndrome.

Antibodies↗
PubMed1976

Platelet function in the Chediak-Higashi syndrome.

Platelet function studies were performed on two patients with the Chediak-Higashi syndrome, one of whom had a history of easy bruising unrelated to thrombocytopenia. Both patients had prolonged bleeding times, abnormal platelet aggregation, and a defect of platelet storage granules, manifested by reduced platelet ADP, an increased ATP/ADP ratio, increased adenine nucleotide specific radioactivity after 3H-adenine labeling, and decreased platelet uptake of radioactive 5-hydroxytryptamine. These findings confirm preliminary data in animals with the Chediak-Higashi syndrome, provide and explanation for impaired primary hemostasis in these patients, and illustrate another disorder in which platelet storage-pool deficiency occurs.

Adenosine Diphosphate↗
PubMed1976

Distribution of phospholipids, fatty acids, and platelet factor 3 activity among subcellular fractions of human platelets.

As compared with other methods, our recently reported method for subcellular fractionation of human platelets improves the separation of mitochondria, alpha granules, and lysosomal enzyme activities. The relative purity of these fractions has led us to undertake the present study to compare the subcellular distribution of phospholipids, fatty acids, and platelet factor 3 (clot-promoting) activity. Two findings pertaining to distribution of phospholipids were entirely new. (1) In the alpha granule zone, plasmalogen phosphatidyl ethanolamine peaked at the expense of diacyl phosphatidyl ethanolamine. (2) The fatty acid composition of the membrane lysophosphatidyl choline suggested that it may have been formed by the action of platelet phospholipase A2 activity. The fatty acids of the membranes showed a markedly asymmetrical distribution in noncholine versus choline phospholipids. The latter held 94%, 72%, and 85%, respectively, of the total content of 16:0, 18:1, and 18:2 fatty acids, whereas 55% of the 18:0, 72% of 20:4, and 67% of higher polyenoic acids other than 20:4 were esterified to the noncholine group. The most important new information related to clot-promoting activity, which, on the basis of protein content, was highest in the membrane fractions, but on the basis of phospholipid content in the nonmembranous fractions. The discussion centers on possible explanations for this novel finding.

Blood Coagulation Factors↗
PubMed1975

Distribution of fibrinogen, and platelet factors 4 and XIII in subcellular fractions of human platelets.

The distribution of fibrinogen, platelet factor 4 (heparin-neutralizing factor) and factor XIII amongst subcellular fractions of human platelets was determined. It was found that fibrinogen and platelet factor 4 peaked sharply in the region of the density gradient previously shown to be heavily enriched with alpha-granules. By contrast, factor XIII, fibrin-stabilizing factor, was found exclusively in the supernatant.

Blood Coagulation Factors↗
PubMed1972

Prostaglandins in the preparation of blood components.

Prostaglandin E(1) significantly improved the separation of blood components in blood bags. The recovery in vivo and the life-span values of the platelets were not altered. The hemostatic effectiveness of platelets treated with prostaglandin was shown to be normal in man.

Autoradiography↗