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J Gras

Publications and source records attributed to J Gras.

102 records · Page 6Linked to original sources
PubMedDate not supplied

[Lipids and beta-lipoproteins in hepatic cirrhosis].

The authors carried out a study of serum lipids and beta-lipoproteins using chemical methods commonly available in clinical pathological laboratories. The study was based on 72 men and women who were chemically and clinically healthy and 41 other patients with biopsy confirmed hepatic cirrhosis, clinically decompensated. In cirrhotic patients there is a decrease in lipid and beta-lipoprotein values in serum. In plasma cirrhotics show a decrease in beta-lipoproteins. In addition the beta-lipoprotien molecule has a different make-up in cirrhotics which statistically is significantly altered from that seen in healthy patients. The graphic correlation between cholesterol, phospholipids and esterified fatty acids in serum as well as in beta-lipoproteins shows a different theoretical equation in the healty and cirrhotic patient. The beta-lipoproteins in cirrhotics are less atherogenic than the corresponding molecules in healthy individuals. The results here presented suggest that there is an important quantitative and qualitative alternation in lipid metabolism and in the biosynthesis of plasma lipoproteins in the uncontrolled cirrhotic.

Blood Protein Electrophoresis↗
PubMedDate not supplied

The immunogenicity of dinitrophenylated polyacrylamide and the adjuvant effect of polyacrylamide.

Dinitrophenyl-substituted polyacrylamide (PAAm-DNP) is weakly immunogenic in guinea pigs and rats. Only 2-mercaptoethanol-sensitive IgM antibodies are elicited, and no immunological memory in guinea pigs is appreciated. A 15000-fold carrier excess, given 6 days before an immunogenic dose of PAAm-DNP, does not impair the anti-DNP response. Different doses of PAAm failed to increase the level of natural anti-DNP or anti-sulfanilic acid antibodies, either in guinea pigs or rats. Nevertheless, when given together with sheep red blood cells. PAAm increases the anti-sheep red blood cell humoral immune response in rats. It is suggested from the above data that the PAAm-DNP immunogenicity is not accounted for by the 'two-signal' model of B-cell activation (via 'associative antibodies'), nor by a model that ascribes B-cell activation to the polyclonal B-cell activating properties of the carrier. However, the possibility that the adjuvant effect showed by PAAm plays a role in allowing the conjugate PAAm-DNP to be immunogenic, remains an open question, and must be further investigated.

Acrylamides↗
PubMedDate not supplied

Action of persistent administration of a hapten with a reactive group (TNBS) and mono-or divalent conjugates of hapten to molecules without other reactive groups on anti-TNP-LPS response.

The intrinsic tolerization mechanisms of the B cell have been postulated either at the level of membrane receptor blockade, before the appearance of membrane receptors, or more intracellularly. For the first possibility a certain multivalence or epitope/hapten density of the antigen molecule is required. Tolerance has been induced by free haptens that possess a reactive group, but haptens lacking such a reactive group may not necessarily be tolerized. We studied the effect on a possible response to trinitrophenyl-lipopolysaccharide (TNP-LPS) by persistent stimulation of immature Swiss mice with: a free hapten containing a reactive group (trinitrobenzenesulfonic acid of TNBS), the low M.W. trinitrophenyl (TNP)-glycine conjugate, and dinitrophenyl (DNP)-polyethylene glycol conjugates; the M.W. of polyethylene glycol being 6,000, 20,000 and 35,000 respectively. Persistent injection of TNBS hapten profoundly tolerated the response to TNP-LPS, whereas the administration of TNP-glycine and DNP-polyethylene glycol conjugates not only fails to tolerate the response, but might stimulate it. Possible explanations for these results are discussed; the tolerogenicactivity of TNBS is ascribed to its binding to another receptor or membrane component, thus impairing "capping" formation by the specific receptor. Alternatively, by acting more intracellularly, TNBS may inhibit the B-cell maturation/differentiation. It would be interesting to find out whether the other conjugates, which are stimulant, could also be tolerated when inoculated for a very long period of time, as has been shown to happen with many antigens administered in immunogenic doses for several months.

Animals↗
PubMedDate not supplied

[Polyclonal stimulation activates the basal level of IgM and IgG plaque-forming cells against sheep erythrocytes without inducing a change from IgM to IgG].

In previous works, we have postulated the existence of an immunological equilibrium between persistence of the antigen presence and the B-cell maturation-differentiation; from this hypothesis, it follows that the antigen presence induces the IgM to IgG switch and the final exhaustion of the response which persists if the antigen stimulation persists. On the basis of those results, we have considered of interest to study the direct and indirect polyclonal activation of the background of murine plaque-forming cells (PFC), against sheep erythrocytes. We have investigated this activation by different doses of mitogens, which activate B cells, thus producing various cellular proliferations. The goal was to find out whether polyclonal activation increased the background (as expected) but did not change the IgM/IgG PFC ratio, probably because of a lack of antigenic stimulation. As mitogens, we have used: E. coli lipopolysaccharide (LPS), a known polyclonal activator of B cells which causes a proportional increase in the number of background plaque-forming cells to a given antigen, and pokeweed mitogen (PWM) which, although less frequently used, has been shown to stimulate both T and B lymphocytes. Female Swiss albino mice have been used; 10 mice per group for both control and test groups. The mitogens were administered according to the following doses and protocol: LPS-1 dose of 10, 50 or 100 micrograms; 3 doses of 10, 50, or 100 micrograms (1 dose per week). PWM-1 dose of 50, 100 or 200 micrograms; 3 doses of 50 or 100 micrograms (1 dose per week).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

[Parallelism between the kinetics of cross-reaction responses (anti-TNP and anti-DNP) and differences from the anti-LPS response when challenged with TNP-LPS immunization].

The multi-functionality of a given antibody, even monoclonal antibody has recently been shown; this raises the possibility that the specificity of an antiserum be due to a population phenomena; i.e., the specificity would be the net result of the affinity of the various antibodies to the same hapten or antigenic determinant. We have shown in many reports, that prolonged and persistent immunization eventually leads to the exhaustion of the response, and this response ceases upon discontinuation of the antigen stimulation. We have therefore postulated the existence of an immunological equilibrium or antigen-dependent immunologic homeostasis, which can be set at different levels and this explains the formation or lack of formation of autoantibodies. This is why we considered it interesting to study the kinetics of the anti-TNP antibody response triggered by persistent and long-lasting immunization of rabbits with TNP-LPS; it was also interesting to study the antibody response to LPS (the latter being a component of the conjugate) and the antibody response to the TNP-cross-reacting DNP and MNP haptens. A group consisting of 6 big albino rabbits was persistently immunized with TNP-LPS (200 micrograms) 3 times per week for 14 weeks and, thereafter, with 2 mg 3 times per week for 26 weeks. Serum anti-TNP and anti-LPS antibodies were titrated respectively with the TNP-Srbc and LPS-Srbc conjugates. Anti-TNP antibodies were titrated before and after absorption of serum with the TNP-EH, DNP-EH and MNP-EH conjugates.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗