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Biomedical subjects

J S Finlayson

Publications and source records attributed to J S Finlayson.

At least 37 records · Page 2Linked to original sources
PubMed1983

Activation of factor XII by dextran sulfate: the basis for an assay of factor XII.

A system was developed for studying the activation of factor XII (Hageman factor) in the presence of dextran sulfate (DS). Salient features of the system included low ionic strength (0.08), low concentration of factor XII (approximately 1/10,000 that in normal plasma), and an excess of exogenous prekallikrein (PK). In this system, factor XII was rapidly converted to the 80,000 molecular weight (mol wt) form of factor XIIa (alpha-factor-XIIa). Once formed, the factor XIIa converted PK to kallikrein at a rate that was proportional to the amount of factor XII originally present in the incubation mixture. This system was used to construct a simple sensitive assay for factor XII in plasma and other biologic samples. The kallikrein produced was measured spectrophotometrically with the chromogenic substrate (H-D-Pro-Phe-Arg-p-nitroanilide (S-2302). This assay was shown to be independent of the high molecular weight kininogen and the PK content of the sample being analyzed. The measurements obtained were consistent with fundamental enzymologic principles and, if desired, could be processed with a simple calculator program to achieve linear standard curves. When applied to the quantitation of factor XII in plasma, the assay yielded values in close agreement with those determined by coagulant assay or by radial immunodiffusion.

Dextran Sulfate↗
PubMed1983

Standardization of the antibody to hepatitis A virus (anti-HAV) content of immunoglobulin.

A batch of standard immunoglobulin was selected as a United States Reference Hepatitis A Immunoglobulin. Subsequent to its testing in research laboratories, public health laboratories, hospitals and universities throughout North America and Europe, this immunoglobulin was provided to the World Health Organization and accepted as an International Hepatitis A Immunoglobulin Reference Preparation. This reference preparation is provided lyophilized in flame-sealed ampules which have been back-filled with argon. When the contents of one ampule are reconstituted to a volume of 1.0 ml, the reciprocal end-point dilution titer of anti-HAV in this reference preparation is approximately 1:500 by competitive-inhibition radioimmunoassay (RIA). Based on data in the literature and that obtained from testing more than 200 batches of immunoglobulin manufactured in the United States between 1967 and 1977, it appears that the level of anti-HAV in the reference preparation could be achieved in each batch of immunoglobulin. Standardization will assure the continued and consistent efficacy of immunoglobulin batches for prophylaxis against hepatitis A.

Antibodies, Viral↗
PubMed1982

Preparation of beta-XIIa (Hageman factor fragment) from human plasma.

beta-Factor XIIa (beta-XIIa, Mr approximately 30,000) was isolated from human plasma by a procedure which utilized, as an initial step, the adsorption of Factor XII to celite. Activation of Factor XII and subsequent release of beta-XIIa was brought about by the proteolytic action of co-adsorbed kallikrein. Two successive chromatographic procedures were then used to achieve a final purification of 4,420-fold over plasma and an overall field of 2.3 mg of beta-XIIa per liter.

Adsorption↗
PubMed1981

Antibodies to hepatitis A virus in immune serum globulin.

Two hundred one immune serum globulin (ISG) lots manufactured in the US between 1967 and 1977 were tested for antibodies to the hepatitis A virus (anti-HAV) by a competitive-inhibition radioimmunoassay (RIA); a lesser number were also tested by immune adherence hemagglutination (IAHA). The percentage of ISG lots that contained anti-HAV with a titer of 1:100 or greater by RIA was 50% for those manufactured in 1967, 69% for those manufactured in 1972, and 100% for those manufactured in 1977. The percentage of lots with anti-HAV titers equal to or greater than 1:500 by RIA was 7% in 1967, 18% in 1972, and 70% in 1977. Only ten lots of ISG (5%) had anti-HAV titers of 1:1,000 or greater by RIA; seven of these were manufactured in 1977. Both the mean titer of anti-HAV in ISG lots and the percentage of lots containing significant titers of this antibody appear to have increased in the US over the past ten years. This may reflect the increased use of source plasma from paid plasmapheresis donors in the US during this period. The lower titers of anti-HAV in the older lots of ISG studied were shown not to be due to fragmentation of antibody molecules during storage.

Antibodies, Viral↗
PubMed1980

Contact-activated factors: contaminants of immunoglobulins preparations with coagulant and vasoactive properties.

The intramuscular or intravenous administration of ISG prepared from human plasma by ethanol fractionation can elicit such reactions as pain at the injection site, flushing, and even hypotension. Similar adverse reactions to plasma protein fraction, a volume expander also made by ethanol fractionation, have been associated with PKA (Hageman factor fragments) in the product. Twenty-five lots of commercial ISG were therefore analyzed for PKA and kallikrein, components of the contact activation system which could mediate such reactions through the generation of kinins in recipients. Kallikrein activity ranged from undetectable levels to > 60% of the total potential kallikrein activity in normal plasma. PKA, which was measured by its ability to catalyze the conversion of prekallikrein to kallikrein, ranged from 5% to 3950% of the activity in a reference plasma protein fraction that had caused hypotension. All but five lots increased vascular permeability in the guinea pig. The five lots which caused no increased were also the lowest in PKA and kallikrein activity. When ISG ws subjected to gel chromatography to separate the enzymic contaminants from immunoglobulin G, only the fractions containing PKA and/or kallikrein increased vascular permeability. Several lots of ISG shortened the nonactivated partial thromboplastin time of normal plasma fro 236 sec to 38 to 55 sec. During gel chromatography, coagulation activity was eluted in a position corresponding to a molecular weight of 150,000; it was inhibited by antibody to human factor XI. These data indicate that factor XIa is responsible for the coagulant activity observed and that PKA and/or kallikrein are potential mediators of vasoactive reactions to ISG.

Animals↗
PubMed1980

Quantitation of monomeric and non-monomeric forms of albumin.

The use of polyacrylamide gel electrophoresis for the quantitation of albumin dimer in commercial albumin samples typically results in an overestimation of the percentage of dimer, as a consequence of significant deviations from Beer's law. This report describes a polyacrylamide gel electrophoresis technique which employs an internal standard for quantitation of albumin dimer. A constant amount of beta-2-glycoprotein I is added to the sample prior to electrophoresis, and the amount of albumin dimer is determined by comparison to that of beta 2-glycoprotein I. A number of commercial albumin solutions were analyzed by this technique; the results were in accord with those obtained by gel permeation chromatography and demonstrated the utility of this method as a rapid screening technique.

Chromatography, Gel↗
PubMed1980

Effects of lipid A and liposomes containing lipid A on platelet and fibrinogen production in rabbits.

The effect of the lipid A moiety of endotoxin on platelet and fibrinogen production was studied in rabbits. Lipid A was infused intravenously in doses ranging from 1 to 100 micrograms/kg body mass; 18 hr later, selenomethionine-75Se was injected intravenously and its incorporation into fibrinogen and platelets determined. Lipid A in saline stimulated fibrinogen and platelet production, but the dose required was 50--100 times that required for an intact endotoxin. Although lipid A solubilized in triethylamine (TEA) was at least 60 times more active in the Limulus amebocyte lysate assay than was lipid A suspended in saline, the sensitivity of platelet and fibrinogen production to solubilized lipid A was increased only twofold. Incorporation of lipid A into liposomes had no effect on its Limulus activity. Lipid A in liposomes continued to stimulate platelet, but not fibrinogen, production. Leukopenia that was induced by lipid A in TEA did not occur when rabbits received the same dose of lipid A in liposomes. Lipid A, like intact endotoxin, can stimulate platelet and fibrinogen production and induce leukopenia but the doses required are high. The low solubility of lipid A in aqueous solutions may be only one factor that determines its biologic activity.

Animals↗
PubMed1978

Hypotension associated with prekallikrein activator (Hageman-factor fragments) in plasma protein fraction.

Thirteen lots of plasma protein fraction made by one manufacturer were implicated in 23 recent reports of hypotension in surgical patients. Four of these patients required resuscitation after rapid administration of the product in the postoperative period. All implicated lots had prekallikrein-activator activity but low levels of bradykinin and kallikrein. The prekallikrein activator was identified as Hageman-factor fragments by molecular weight (35,000 as estimated by gel chromatography), isoelectric point (4.2 to 4.4), and inhibition by antibody to Hageman factor. These data suggest that Hageman-factor fragments are potent hypotensive agents, presumably because they trigger the generation of bradykinin in recipients. Prekallikrein-activator activity, usually at levels lower than those in the initial 13 implicated lots, was frequently detected in plasma protein fraction made by other manufactures. Several of these lots were associated with additional reports of hypotension. Prekallikrein-activator activity rarely occurred in albumin.

Bradykinin↗
PubMed1978

Amino acid sequence of chicken fibrinopeptide A.

Chicken fibrinopeptide A was isolated and the complete amino acid sequence was established. It is a pentadecapeptide with the sequence of Gln(Pyr)-Asp-Gly-Lys-Thr-Thr-Phe-Glu-Lys-Glu-Gly-Gly-Gly-Gly-Arg and is homologous with mammalian fibrinopeptide A. Two peptides which appear to be derivatives of fibrinopeptide A were also isolated. One of these appeared to be fibrinopeptide A with NH2-terminal pyroglutamic acid; the other was fibrinopeptide A which lacked the COOH-terminal arginine residue.

Amino Acid Sequence↗