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Biomedical subjects

S Karpatkin

Publications and source records attributed to S Karpatkin.

At least 127 records · Page 7Linked to original sources
PubMed1979

Humoral factor that specifically regulates factor X levels in rabbits (coagulopoietin-X).

A heat-stable humoral substance (coagulopoietin-X) is present in rabbits partially depleted of Factor X, which is capable of raising Factor X levels when injected into recipient rabbits. Rabbits were partially depleted of Factor X by slow infusion of a globulin fraction of goat anti-rabbit Factor X antibody. This resulted in the reduction of Factor X to 40--50% of normal at 1 h and 60--70% of normal at 6 h. No effect was noted on levels of Factors II, V, or VII. Plasma from these animals, when injected into 10 recipients, specifically raised Factor X levels when measured by four different assay: one-stage assay with bovine VII- and X-deficient plasma and Russell's viper venom; one-stage assay with human X-deficient plasma and thromboplastin; chromogenic substrate assay with Russell's viper venom; and an immunologic assay (Laurell technique). No rise was noted in two control experiments in which normal plasma was injected into recipient rabbits from 2 rabbits injected with a globulin fraction of normal goat serum, nor in 12 rabbits injected with plasma from normal rabbits, nor in 5 rabbits injected with boiled plasma from normal rabbits. The rise in biologic activity of 120--150% of base line was significantly greater than the rise in immunologic activity of 114--117% of base line (P less than 0.05) on 3 different days, suggesting the production of a molecule with greater specific activity rather than increased protein synthesis.

Animals↗
PubMed1979

A solid-phase radioimmunoassay for bound anti-platelet antibody: studies on 45 patients with autoimmune platelet disorders.

A highly sensitive, solid-phase radioimmunoassay has been developed for detecting platelet-bound immunoglobulin, which employs 125I-staphylococcal protein A. The assay detects platelet IgG at the picogram level, which is 10- to 50-fold more sensitive than currently available procedures. It is relatively simple and can be performed on frozen extracts from as little as 2 X 10(5) platelets. Washed platelets are frozen, thawed, sonicated, and centrifuged at 20,000 X g. The supernatant, which contains 7S IgG, is applied in serial dilution to the wells of a plastic microliter plate capable of adsorbing protein. Commercial rabbit anti-human IgG is added and then "sandwiched" to 125I-staphylococcal protein A. The wells are removed from the plate and assayed for radioactivity. Thirty-two of 35 thrombocytopenic patients (92%) with ATP had platelet IgG values greater than those of controls by 2 S.D. and averaged 150 +/- 145 (S.D.) ng/10(6) platelets; 11 healthy controls, 11.4 +/- 7.4 ng; five "thrombocytopenic" controls, 9.7 +/- 13 ng. The platelet count (X) correlated inversely with IgG/platelet (Y) according to the equation: Log Y = -0.66 log X + 4.8; r = -0.71, p less than 0.001. Elevated platelet IgG levels were also found in 5 ATP patients in "apparent remission"; two of four had evidence for compensated thrombocytolysis (increased megathrombocytes). Elevated platelet IgG levels were also found in six patients with thrombocytopenia secondary to lymphoproliferative disorders.

Autoantibodies↗
PubMed1978

Heterogeneity of rabbit platelets. VI. Further resolution of changes in platelet density, volume, and radioactivity following cohort labelling with 75Se-selenomethione.

Rabbits were injected intravenously with a cohort platelet label, 75Se-selenomethionine Platelet-rich plasma was separated into five different platelet density fractions on each of seven days by repetitively centrifuging the same sample of platelet-rich plasma at increasing gravitational force. The heaviest platelet sediment fraction was enriched with smaller platelets. Incorporation of isotope into the heaviest platelet fraction was considerably greater than incorporation into the highest platelet fraction, i.e. heavy--light specific activity ratio was 9.63, on day 1. The ratio of the heaviest platelet fraction specific activity to the specific activities of the platelets sedimented at higher g forces (lighter-smaller platelets), generally decreased on each day for 4--6 d by a factor of 2.8--7.0-fold. Whereas incorporation of isotope into the heaviest platelet fraction declined on days 3--4, incorporation into the lightest three fractions remained the same. Cohort platelet survival curves revealed a significant lag period of 1--2 d for the incorporation of isotope into the lightest three platelet fractions compared to the heaviest two platelet fractions. The mean platelet survival of the lightest two fractions was significantly shorter than the mean platelet survival of the heaviest three fractions. SDS-polyacrylamide gel electrophoresis of the platelet cell sap of the five platelet fractions generally revealed 10 prominent protein bands for the heaviest platelet fractions. The lightest platelet fraction, which comprised 16% of the harvested platelet population, had six absent to markedly diminished platelet proteins of modecular weights between 142 000 and 46 000 daltons. The data are compatible with two models: (1) Heavy-large platelets are, on average, young platelets which become lighter-smaller platelets while losing platelet membrane and cell sap components with time. (2) Heavy-large platelets and light-small platelets are produced independently by specific megakarocytes. The heavy-large platelets incorporate more isotope than lighter-smaller platelets (possibly because of their megakarocyte precursor). However, they are released earlier into the circulation than lighter-smaller platelets and are therefore younger platelets.

Animals↗
PubMed1978

Hypersplenic thrombocytopenia differentiated from increased peripheral destruction by platelet volume.

Platelet volume distribution was examined in 16 patients with hepatosplenomegaly and platelet counts of 45 000 to 90 000/mm; 12 patients with autoimmune thrombocytopenia and randomly matched platelet counts; and 20 normal subjects. Five platelet volume variables of increasing platelet size were defined from the averages of 20 normal curves. Patients with hypersplenism had decreased volume values of 78% to 87% (mean, 83%) of the average normal population (P less than 0.001). Patients with autoimmune thrombocytopenic purpura had values significantly greater than normal by 124% to 149% (mean, 134%) (P less than 0.001). Patients with autoimmune thrombocytopenic purpura, when compared with hypersplenic patients, had significantly greater platelet volume values ranging from 154% to 174% (mean, 161%), P less than 0.001. We concluded that patients with hepatosplenomegaly have smaller platelets in their peripheral blood and a platelet volume distribution that can be distinguished easily from patients with autoimmune thrombocytopenic purpura, despite comparable platelet counts.

Autoimmune Diseases↗
PubMed1978

Identification of a coagulopoietin for prothrombin.

A coagulopoietin specific for factor II has been demonstrated in the rabbit, and termed 'coagulopoietin-II'. A goat antiserum was used to lower the factor II level in a rabbit. When plasma from this rabbit was then injected into other rabbits, factor II rose in the recipients without increase in other coagulation factors measured (V, VII, and X). The coagulopoietin is stable to boiling for 30 minutes, and appear to have a molecular weight of less than 30,000.

Animals↗
PubMed1977

Red-cell and platelet fragmentation in idiopathic autoimmune thrombocytopenic purpura.

We investigated the abnormal small-particle spike discerned in the platelet-rich plasma of patients with severe idiopathic autoimmune thrombocytopenic purpura. By electron microscopy, erythrocyte as well as platelet fragments were found in the 27,000 X g plasma sediment of 15 patients with severe disease. These fragments were not observed in the plasma sediment of 12 normal subjects, two healthy asplenic subjects, three patients with thrombocytopenia of nonimmunologic origin, and two with autoimmune thrombocytopenic purpura in remission. Weak complement sensitization of red blood cells was noted in seven out of 12 patients with the disease. Coating of red blood cells with IgG or IgM was not detected in these patients. Whereas erythrophagocytosis was conspicuously absent, phagocytosis of intact platelets as well as platelet fragments and other cellular debris was frequently observed. Autoimmune mechanisms may be directed against erythrocytes as well as platelets in most cases of severe idiopathic autoimmune thrombocytopenia.

Autoantibodies↗
PubMed1977

The platelet factor 3 immunoinjury technique re-evaluated. Development of a rapid test for antiplatelet antibody. Detection in various clinical disorders, including immunologic drug-induced and neonatal thrombocytopenias.

A modified version of the platelet factor 3 immunoinjury technique for the detection of antiplatelet antibody is described in detail; heat-inactivated sera and frozen platelets are employed. The modification allows the results of the test to be available within 4 to 5 hours after drawing the blood sample, in contrast to the 3 days required in the original method. The technical work involved is significantly reduced. The reproducibility of the technique is improved. Results obtained with the two tests correlate well. Data accumulated in 458 cases of clinical disorders associated with antiplatelet antibody are reported. Drug-dependent antiplatelet antibody was demonstrated in 26 cases of thrombocytopenia associated with 19 different drugs. Data are also presented for 23 cases of neonatal thrombocytopenia.

Autoantibodies↗
PubMed1976

Evidence suggesting the regulation of a coagulation factor levels in rabbits by a transferable plasma agent.

New Zealand white rabbits were given 30 ml of goat serum intravenously. This procedure resulted in an immediate decrease in platelet count, fibrinogen, and levels of coagulation factors II, V, VII, and X, due to consumption coagulopathy. These factors returned toward baseline levels approximately 12 hr after the injection. Plasma from rabbits who had received goat serum 48 hr previously (donor rabbits) was injected into recipient rabbits. This procedure resulted in a slight rise in the level of coagulation factor II (range, 20%-30%) and a significant rise in factors V (35%-75%), VII (35%-235%), and X (35%-75%) in the recipients. When plasma from control donor rabbits who had not received goat serum was injected into recipients, there was no change in these coagulation factors. It is postulated that the reduction in coagulation factor levels in donor rabbits induces a "coagulopoietin" for each factor or one "coagulopoietin" for all factors which stimulates increased synthesis and/or release of these factors in recipient rabbits.

Animals↗