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Biomedical subjects

P Sizaret

Publications and source records attributed to P Sizaret.

At least 19 recordsLinked to original sources
PubMed2000

Different role of platelet glycoprotein GP Ia/IIa in platelet contact and activation induced by type I and type III collagens.

The role of glycoprotein Ia/IIa was studied during platelet contact and aggregation induced by type I and type III collagen. The anti-glycoprotein Ia/IIa (6F1) antibody inhibited type I collagen-induced aggregation but did not inhibit the first contact between platelets and collagen. In contrast, it was without effect either on type III collagen-induced contact or platelet interaction with the subendothelium in a static assay. Platelet aggregation induced by type III collagen was only slightly slowed down by 6F1 but pp72 spleen tyrosine kinase phosphorylation was not modified even at concentrations of 6F1 that completely blocked platelet activation induced by type I collagen. Our results indicate that glycoprotein Ia/IIa is not a primary binding site for type I or type III collagen on the platelet membrane. This receptor is more specifically involved in type I collagen-induced platelet spreading and aggregation.

Antibodies, Monoclonal↗
PubMed1988

Evolution of activities in international biological standardization since the early days of the Health Organisation of the League of Nations.

The main activities in international biological standardization during the 18 years that followed the first international biological standardization meeting in London in 1921 were concerned with expressing the potencies of test preparations in comparison with reference materials. After the Second World War, however, it became clear that the testing of biological substances against international reference materials was only one among several measures for obtaining safe and potent products. The activities in international biological standardization were therefore widened so that, by the strict observance of specific manufacturing and control requirements, it was possible to gain further in safety and efficacy. At the end of 1987, 42 international requirements for biological substances were available and were being used as national requirements, sometimes after minor modification, by the majority of WHO's Member States. This is of utmost importance for the worldwide use of safe and potent biological products, including vaccines.

Biological Products↗
PubMed1987

[Paranoid reactions and culture].

Paranoid Reaction (or bouffée délirante) according to the french classification was the basic psychosis of primitive societies. It corresponds to a need of defense of restructuration or restitution according to a pattern of "misconduction" admitted by the cultural environment. Paranoid reaction, in this respect, offers some relative good pronostic as soon as the goal is reached even if the previous personality remains modified. Paranoid reaction may get closer to hysterical crepuscular states. Some symptoms may also evoke schizophrenias. Evolution toward a lasting psychosis may be considered only in case the process of deculturation/acculturation is already engaged in an irreversible way and the defensive mode presented in the new cultural system shows schizophrenic patterns. Quick transformations and strong cultural pressures, trough that primitive societies are going, might increase dramatically chronic evolution of paranoid reactions. A case has been related to illustrate those considerations.

Acculturation↗
PubMed1984

An enzyme-linked immunosorbent procedure for assaying aflatoxin B1.

A polyclonal rabbit antibody preparation against aflatoxin B1 (AFB1), produced by immunization with a bovine serum albumin-AFB1 conjugate, has been used to develop an enzyme-linked immunosorbent assay (ELISA). AFB1-ovalbumin, obtained by reacting either AFB1-8,9-dichloride or -8,9-dibromide with ovalbumin, was used to coat each well of a polyvinyl microtitre dish. Rabbit antibody, diluted 1:100 000, was added to each well and left to attach for 90 min, then the excess was washed off with phosphate-buffered saline/Tween. Anti-rabbit IgG coupled to peroxidase was then added, left for 90 min and the excess washed away. Residual peroxidase activity was assayed using tetramethylbenzidine as substrate; the reaction was quenched at the end of the 15-min incubation period with 2 N sulfuric acid. Inhibitor studies to assay AFB1 and related compounds in urine involved prior incubation of the diluted anti-AFB1 antibody with inhibitor for 60 min at 37 degrees C, prior to dispensing into the multi-well plates. Inhibitor studies with AFB1 showed inhibition over a concentration range of 10(-1) to 10(-5) micrograms/ml. The minimum detectable concentration was approximately 10(-5) micrograms/ml (0.032 pmol/ml). Anti-AFB1 antibody was also inhibited by iro-AFB1-DNA, one of the forms of AFB1-DNA, as well as by AFB1-guanine. Undiluted urine from normal subjects inhibited antibody binding to plates; this inhibition could be prevented by either dilution or extraction procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Aflatoxin B1↗
PubMed1983

Preparation of aflatoxin B1-BSA conjugate with high hapten/carrier molar ratio.

We reported previously on the properties of an anti-aflatoxin B1 (AFB) antiserum raised with a conjugate in which AFB is coupled at the C8 position to bovine serum albumin (BSA). The hapten/carrier protein molar ratio of the conjugate was 14. We have since been able to optimize the coupling conditions, resulting in the preparation of another conjugate, with a molar ratio of 45. Comparison of the 2 conjugates by double-gel immunodiffusion analysis shows that little BSA 'activity' remains on the conjugate with a high molar ratio; on the other hand, its capacity to precipitate in the presence of anti-AFB antibodies is increased.

Aflatoxin B1↗
PubMed1982

Comparative assays in three laboratories of serum specimens containing pregnancy-specific beta 1 glycoprotein with different proportions of the alpha variant.

Following several reports that the alpha component of pregnancy-specific beta 1 glycoprotein (SP1) gives dose-response curves that are flatter than those of the beta component when assayed by radioimmunoassay of the competitive type, a collaborative study was carried out by 3 laboratories to examine whether radial immunodiffusion or rocket immunoelectrophoresis give similar result. Five sera from pregnant women at the 34-39th week of gestation with beta : alpha ratios of 0.8-4.7 were assayed by both the latter methods against either the IARC 78 610 reference preparation of the SP1 Behring standard. When preparations were assayed by rocket immunoelectrophoresis (two laboratories), the dose-response curves were parallel. When preparations were assayed by radial immunodiffusion (two laboratories), parallelism was observed (one laboratory) after the addition of polyethylene glycol, the presence of which is necessary to visualize immune precipitates in which alpha is involved. Discrepancies observed when methodologies such as competitive radioimmunoassay are used, in which there are limited amounts of antibodies, are explained, at least partially, but the fact that the beta component has a greater relative affinity for the antibody as higher concentrations of beta : alpha mixtures are assayed. However, when antibody is present in excess, as in radial immunodiffusion and rocket immunoelectrophoresis, no such difference in affinity seems to occur.

Australia↗
PubMed1982

Inhibition by specific antibodies of the mutagenicity of aflatoxin B1 in bacteria.

Two anti-aflatoxin B1 antisera, antiserum 'O' and antiserum 'C', were raised against conjugates in which the bovine serum albumin protein carrier was coupled to aflatoxin B1 derivatives at carbon 1 or 8. Their action was investigated in Salmonella thyphimurium assays using a fortified 9000 x g supernatant (S9) of rat liver homogenate or using rat hepatocytes as the metabolic activation system. In all cases, a substantial reduction in mutagenicity was observed: the mutagenicity caused by 12.5 ng aflatoxin B1 was inhibited by 50% with 2 microliters of antiserum 'O' and with 12 microliters of antiserum 'C' when activation was catalysed by rat liver supernatant; the mutagenicity of 3.31 micrograms aflatoxin B1 was inhibited by 50% with 25 microliters of antiserum 'O' in experiments using hepatocytes as the metabolic activation system. Several lines of evidence indicate that the inhibition is caused by specific antibodies. The molar ratios of aflatoxin B2 or aflatoxin G2 to aflatoxin B1 required to reduce by 50% the effect of antisera on aflatoxin B1 mutagenicity were 2.9-76-fold higher than those required to reduce by 50% the tracer antibody binding in radioimmunoassay. Possible mechanisms by which anti-aflatoxin B1 antisera inhibit aflatoxin B1 mutagenicity are discussed.

Aflatoxin B1↗
PubMed1982

Detection of aflatoxins and related metabolites by radioimmunoassay.

Rabbit (outbred albino New Zealand White) antisera have been raised against aflatoxin B1 (AFB1) using as immunogen conjugates in which the hapten was coupled to bovine serum albumin (BSA) either through C1 or C8 with the oxime and the dichloride derivatives of AFB1 as intermediates. Radioimmunoassay (RIA), with [3H]AFB1 as tracer, showed that the antiserum prepared with the conjugate in which BSA was coupled to the AFB1 oxime derivative was highly specific to AFB1, whereas the antiserum raised against the conjugate in which BSA was coupled to AFB1 through the AFB1Cl2 derivative (C-antiserum) cross-reacted to a large extent with other aflatoxins, including aflatoxin M1, an important urinary metabolite of AFB1 in several species including humans. AFB1-related metabolites in the urine of inbred BD IV adult male rats given AFB1 orally at doses from 600 pmol to 385 nmol can easily be followed over 9 days by RIA in which the "cross-reactive" C-antiserum is used. This suggests that similar methodologies could be used for the monitoring of human exposure to AFB1.

Aflatoxin B1↗