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Biomedical subjects

L Pechet

Publications and source records attributed to L Pechet.

9 recordsLinked to original sources
PubMed1979

Characterization and experimental use of a monospecific antiserum to factor IX.

Purified human factor IX was used to develop xenogeneic neutralizing and precipitating antibodies. The final antiserum (R2) neutralized only factor IX and was equivalent to 220 Bethesda-inhibitory units. It showed two precipitating lines, one of which disappeared after absorption with human albumin. On immunodiffusion and Laurell immunoelectrophoresis, the albumin-absorbed R2 antiserum showed one precipitin line of identity, or one rocket respectively, with normal plasma, a Red Cross factor IX preparation (rich in factors IX, II and X), the original antigen, and Hemophilia-B antigen-positive plasmas. No line or rocket developed with normal plasma absorbed with aluminum hydroxide or with antigen-negative contained only factor IX neutralizing and precipitating antibodies. Experiments with various factor IX concentrates revealed that the majority contained excess factor IX antigen compared to their coagulant activity. In addition, crossed antigen-antibody electrophoresis uncovered differences in the migration of the factor IX of Konyne preparations, when done in the presence of EDTA or calcium. This monospecific antiserum to human factor IX was subsequently used to investigate a large population of hemophilia B patients and carriers.

Animals↗
PubMed1979

Laboratory prediction of the carrier state in hemophilia B: role of replication of assays.

The authors studied the effect of averaging replicated assays of Factor IX coagulation activity and Factor IX antigen on each plasma specimen in improving the ability to detect carriers of hemophilia B. The improvement resulting from this procedure is particularly marked in tests depending on the linear regression of one characteristic on another to diagnose the carrier state. The effects of averaging assays on the ratio of Factor IX coagulation activity to Factor IX antigen were also explored. The benefits of averaging replications were not greatly increased by use of more than four replications.

Blood Coagulation Tests↗
PubMed1979

Internal synthesis of p23,30 by several lymphoid malignancies.

The aim of this study was to prove the internal synthesis of p23,30 antigen (HLA-D related determinant) on human leukemias and lymphomas on which it has been detected with complement-dependent cytotoxic assays. Murine Ia antigens similar to p23,30 antigen are found on many subsets of cells in the mouse (B lymphocytes, macrophages, allogeneically activated T lymphocytes) and on intercellularly transferred immunoregulatory molecules, which may be adsorbed to other cells. The question exists whether the p23,30 antigen, which occurs on a wide range of human leukemias, is internally synthesized by these tumors or, in some instances, is synthesized by normal lymphocytes and is adsorbed to the leukemic cells. The expression of p23,30 antigen on a limited series of human leukemias and lymphomas was detected by a complement dependent, cytotoxicity assay. The internal synthesis of p23,30 antigen and p44,12 (HLA-A and -B antigens and beta2-microglobulin) was confirmed by immunoprecipitation and these antigens from [35S]methionine labeled, detergent solubilized membranes of tumor cells. In each instance, the synthesis of p23,30 antigen by the malignant cells was confirmed. The distribution of p23,30 antigen (and 1a antigen) on subsets of normal cells and in immunoregulatory molecules was reviewed. In view of these findings, the role of p23,30 antigen in the diagnosis of subsets of human hematologic malignancies was reconsidered.

Antigens, Surface↗
PubMed1978

Some observations on the in vivo effect of propranolol on platelet aggregation and release.

Platelet function was investigated in four normal volunteers, one patient with a mild form of von Willebrand disease, and one with a thrombocytopathy, all taking propranolol. No effect on platelet function attributable to this drug could be demonstrated in any of these subjects. It is suggested that propranolol administered in conventional doses does not impair platelet hemostatic function.

Adult↗
PubMed1978

The effect of trypsin and storage on aggregation and release of human gel-filtered platelets.

Trypsin was studied as an aggregating and release-inducing agent with gel-filtered platelets (GFP) and was compared with ADP, epinephrine and collagen. GFP aggregated irreversibly with final concentrations of 0.5-4 microgram/ml trypsin, 1.6-3.2 micrometer ADP, 2.5-5 micrometer epinephrine and 40 microlite 1/ml soluble collagen. Addition of human fibrinogen to the Tyrode-suspending buffer was required for ADP and epinephrine, but was not necessary for trypsin or collagen. Release of (14C)5HT was obtained with trypsin and collagen using the same concentrations as used in aggregation. GFP stored at room temperature for 48 h were still responsive to trypsin and collagen, whereas aggregability and (14C)5HT release induced by ADP and epinephrine were already impaired 5 h after collection of blood. CP-CPK, an ADP-removing reagent, blocked aggregation and release induced by low trypsin concentrations, suggesting that ADP plays an intermediate role in the mechanism by which trypsin activates platelets. Trypsin appears to be a valuable reagent for studying platelet physiology, particulary following storage.

Blood Coagulation↗