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Biomedical subjects

L Pelletier

Publications and source records attributed to L Pelletier.

At least 91 records · Page 5Linked to original sources
PubMed1987

Down modulation of Heymann's nephritis by mercuric chloride.

The time course of Heymann's nephritis (HN), assessed on proteinuria and immunomorphology, has been compared in Lewis (LEW) rats immunized with BB alone (group A) or injected with HgCl2 and subsequently immunized in a similar manner (group B). Whereas all rats from group A developed typical HN characterized by heavy proteinuria and abundant glomerular immune deposits, rats from group B did not develop or developed a markedly attenuated form of HN; proteinuria was never detectable, immune deposits were absent or minimal. No abnormalities were found in rats injected with HgCl2 alone. In order to explain our findings, we have studied the glomerular and tubular expression of the 330 kD nephritogenic glycoprotein (gp330) as well as the corresponding antibody response. In rats receiving HgCl2, gp330 was normally expressed on BB and glomerular epithelial cells as indicated by in vitro and in vivo binding of anti-gp330 antibodies, but titers of anti-BB and anti-gp330 antibodies were considerably lower than in group A control rats. These findings therefore suggest that HgCl2 acts by its immunodepressive effect recently related to an increase in T suppressor cells. This effect is paradoxical since HgCl2 induces autoimmunity in Brown-Norway rats, and we suggest that it may be akin to observations reported in clinical practice where drugs may be immunostimulatory in some patients and immunodepressive in others. The mercury model may therefore represent a unique tool to evaluate the relationship between genetics and drug-induced immune dysregulation.

Animals↗
PubMed1987

Mercury-induced autoimmune glomerulonephritis: requirement for T-cells.

Mercury-induced autoimmunity in Brown-Norway rats has been shown previously to be due to polyclonal activation of B lymphocytes, requiring the presence of T lymphocytes. Autoimmunity in that strain is characterised by the appearance of an autoimmune glomerulonephritis, by the production of a host of autoantibodies, and by an increase in total serum IgE. In the present study, T-cell deprived rats were tested to assess the role of T cells in the appearance of autoimmune abnormalities in vivo. It will be shown that both BN rnu/rnu and BN 'B' rats, who have virtually no T cells, do not develop autoimmunity following HgCl2 injections. In contrast BN 'B' rats reconstituted with normal T cells, and BN rnu/+ rats, exhibit autoimmune manifestations, including autoimmune glomerulonephritis, quite similar to those observed in Brown-Norway rats. These data demonstrate that T cells are essential for mercury-induced autoimmunity to occur in Brown-Norway rats.

Animals↗
PubMed1987

Effect of methylprednisolone and cyclophosphamide in mercury-induced autoimmune glomerulonephritis.

The effects of methylprednisolone and of cyclophosphamide were tested in mercury-induced autoimmune disease in Brown-Norway rats. Survival, proteinuria, presence of antiglomerular basement membrane bound antibodies and of immune complex type deposits, amounts of circulating immune complexes, and total serum IgE were studied. Serum IgE represents the most sensitive marker in this drug-induced autoimmune disease. Methylprednisolone alone (1.5 mg/kg per day) affected the course of the disease only slightly. Cyclophosphamide (20 mg/kg every other day) given from day 0 completely prevented all the autoimmune manifestations, but the rats were profoundly immunosuppressed. The same protective effect was obtained with lower cyclophosphamide dosage (15 mg/kg on day 0 and then 2 mg/kg per day). More interestingly, cyclophosphamide given from day 10 or 15 (20 mg/kg twice a week or every other day), at a time when the disease was already expressed, resulted in partial or complete recovery, provided that the rats had not exhibited heavy proteinuria before initiation of treatment. Cyclophosphamide is therefore a powerful agent, able to prevent and even to reduce the consequences of polyclonal activation in this model.

Animals↗
PubMed1986

Autoreactive T cells in mercury-induced autoimmune disease: in vitro demonstration.

Mercuric chloride induces in Brown-Norway rats an autoimmune disease due to a T dependent polyclonal activation of B cells. Various autoantibodies and a striking increase in total serum IgE level are observed as consequences of this polyclonal activation. The aim of this study was to investigate the in vitro response of autologous syngeneic normal lymphocytes to lymphocytes exposed in vivo or in vitro to HgCL2. Helper/inducer T cells (W3/25 +) exposed to HgCl2 were found to stimulate normal T lymphocytes in the presence of normal Ia (+) cells. The proliferating T cells also had the helper/inducer phenotype. To demonstrate the potential relevance of this in vitro phenomenon to the autoimmune disease, HgCl2-pretreated T cells were injected into the footpads of normal syngeneic recipients. Draining popliteal lymph nodes contained a highly significant number of both surface IgE positive and IgE containing cells. These experiments demonstrate that HgCl2 induces autoreactive T cells and suggest that these cells may be responsible for the autoimmune disease.

Animals↗
PubMed1986

Effect of prostaglandin E1 in brown Norway rats with mercury-induced autoimmune disease.

The effect of prostaglandin E1 on mercury-induced autoimmune disease in brown Norway rats has been investigated. Daily doses of 6 to 24 micrograms prolonged survival and significantly decreased proteinuria, deposition of immune reactants in the glomeruli, circulating anti-glomerular membrane antibody production, total serum IgE, and circulating immune complex level. A dose of 3 micrograms was also effective but to a lesser degree. These results show the efficiency of prostaglandin E1 in yet another autoimmune disease, show that the beneficial effect of prostaglandin E1 in this model is related to its immunosuppressive effects, and suggest that modification of prostaglandin-mediated suppression induced by HgCl2 might play a role in the pathogenesis of this autoimmune disease.

Alprostadil↗
PubMed1986

[Uterine rupture causing acute defibrination syndrome. Apropos of 3 cases].

The authors report three cases of rupture of the uterus during delivery, complicated by an acute defibrination syndrome. Death resulted in two cases. The sequence of rupture of the uterus----shock----pathological condition of coagulation----great increase in the shock occurred in all three patients. This sequence could only be arrested in one of the three patients who had a total hysterectomy. Partial hysterectomy in the other two was ineffective. These three case histories suggest that total hysterectomy after even partial correction of the haemorrhagic state can be the best treatment in this very serious condition.

Adult↗
PubMed1985

In vivo self-reactivity of mononuclear cells to T cells and macrophages exposed to HgCl2.

Mercuric chloride induces in Brown-Norway rats a polyclonal activation of B cells resulting in a lymphoproliferation and in the production of autoantibodies. Experiments were performed to test the role of cells modified by HgCl2 in the induction of B cell proliferation by using the popliteal lymph node assay. Spleen cells, T cells and peritoneal macrophages exposed in vivo or in vitro to HgCl2 induced a proliferation of T and B cells in the draining popliteal lymph node. Spleen cells from Lewis rats who received HgCl2 were ineffective. These data suggest that modified cells could trigger autologous lymphocyte subsets and be responsible for autoimmunity induced by HgCl2.

Animals↗
PubMed1983

Tannic acid- and thiocarbohydrazide-mediated osmium tetroxide binding in the preparation of human leucocytes for SEM observation.

Normal human leucocytes, successively treated with glutaraldehyde-tannic acid-osmium tetroxide-thiocarbohydrazide-osmium tetroxide-thiocarbohydrazide-osmium tetroxide, were prepared for scanning electron microscopy observation. These cells produced well-contrasted, non-charging scanning images compatible with metal-evaporated material. Further, the mononuclear and polymorphonuclear cells resisted shrinkage during dehydration and critical point drying, thus allowing much improved images at high magnification than those covered with evaporated metal. In all cases at least a second thiocarbohydrazide-osmium tetroxide treatment could not be avoided.

Fixatives↗