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Biomedical subjects

S Thiru

Publications and source records attributed to S Thiru.

At least 55 records · Page 3Linked to original sources
PubMed1992

Familial oesophageal leiomyomatosis and nephropathy.

Four female members of the same family suffering from a rare combination of oesophageal leiomyomatosis and an Alport-like nephropathy are described. The disease is characterized by marked thickening of the oesophageal wall, usually also involving the proximal stomach, with or without discernible leiomyomatous nodule formation. All cases were treated surgically by oesophagectomy with symptomatic relief, and there was no evidence of recurrence on follow-up (2-37 years). The syndrome appears to be dominantly inherited, affects children and young adults, and may also be associated with leiomyomatosis of other viscera. Previously reported cases and possible aetiologies are reviewed, and evidence that this association represents a new variant of Alport's syndrome is discussed.

Adult↗
PubMed1992

Autoantibodies to myeloperoxidase in brown Norway rats treated with mercuric chloride.

BACKGROUND: Mercuric chloride (HgCl2) induces an autoimmune syndrome in Brown Norway (BN) rats characterized by the presence of a number of autoantibodies, including antibodies to glomerular basement membrane. Tissue injury has previously been reported to be rare in this model, but in the accompanying paper we describe changes in a number of organs including a necrotizing leucocytoclastic vasculitis in the gut. Myeloperoxidase (MPO) is one of the target antigens for anti-neutrophil cytoplasm antibodies, that are present in the majority of patients with the human autoimmune disease systemic vasculitis and have been implicated in pathogenesis. There is at present, no animal model for anti-neutrophil cytoplasm antibody positive systemic vasculitis. EXPERIMENTAL DESIGN: Ten BN rats were given five injections of HgCl2, each of 1 mg/kg, over 10 days. Sequential serum samples were tested for autoantibodies to MPO using solid phase assays, indirect immunofluorescence on normal rat neutrophils, and Western blot analysis. The specificity of these antibodies in the solid phase assay was confirmed by inhibition studies with purified antigen, and by testing binding to uncoated plates. Sera from control animals treated with saline were also tested. RESULTS: BN rats given HgCl2 developed antibodies to MPO, which in Western blots bound to similar determinants to those bound by human anti-MPO antibodies. The anti-MPO antibodies resolved spontaneously, with a time course similar to that of the anti-glomerular basement membrane antibodies, but there was no correlation between the two antibody responses in individual animals. There was no anti-MPO activity in sera taken before HgCl2 was given, nor in sera from saline-treated controls. CONCLUSIONS: BN rats treated with HgCl2 develop anti-MPO antibodies. Together with the description in the accompanying paper of necrotizing vasculitis in these animals, these observations suggest that HgCl2-induced autoimmunity in the BN rat may provide a useful model of anti-neutrophil cytoplasm antibody positive systemic vasculitis.

Animals↗
PubMed1992

The "rejection reaction" is not confined solely to the allograft.

The rejection process refers primarily to the destruction of foreign tissues by host immune mechanisms. This process affects host lymphoid tissue profoundly and alters the migration patterns of lymphocytes in recipients of organ allografts. It has been shown that specifically sensitized lymphocytes traffic both to and from the transplant. A considerable amount of knowledge has been gathered on the preferential migration pathways of lymphocytes through lymphoid and mucosa-associated lymphoid organs. The factors regulating lymphocyte migration through non-lymphoid tissue in normal conditions are not well known and even less well understood in the context of graft rejection. In this article we described for the first time migration in a recipient non-lymphoid organ (heart) and it's potentially harmful effects in causing parenchymal damage during renal allograft rejection in the rat model. These lesions were detected during the process of developing a model of chronic renal allograft rejection. The pathogenesis of these cardiac lesions is not fully understood but possible mechanisms include upregulation of homing receptors/adhesion molecules, breakdown of peripheral tolerance and involvement of cross-reacting anti-endothelial antibodies.

Animals↗
PubMed1992

Mercuric chloride-treated brown Norway rats develop widespread tissue injury including necrotizing vasculitis.

BACKGROUND: Mercuric chloride (HgCl2) induces a T cell-dependent autoimmune syndrome in Brown Norway (BN) rats, characterized by polyclonal B cell activation and circulating autoreactive T cells. A number of autoantibodies are produced, including antibodies to glomerular basement membrane, and there are circulating immune complexes. However, histologic evidence of tissue injury in this model has previously been reported to be rare. EXPERIMENTAL DESIGN: Six BN rats were given five injections of HgCl2, each of 1 mg/kg, over 10 days. Controls were four BN rats given equal volumes of saline and 10 Lewis rats given the same amount of HgCl2. Blood samples were taken thrice weekly. Animals were killed at various stages, necropsies performed, and organs histologically examined. The effect of pretreatment with broad spectrum antimicrobial drugs was examined by comparing two further groups of six BN rats: one group was pretreated with tylosin, ivermectin, and metronidazole before HgCl2 was given, and the other group received no pre-treatment. RESULTS: HgCl2-treated BN rats developed inflammation and ulceration of the skin which was most marked at mucocutaneous junctions. Macroscopic examination of internal organs showed hepatomegaly and gross haemorrhagic lesions in the wall of the gut, most marked in the duodenum and caecum. Microscopically, the skin lesions were characterized by a subepidermal mononuclear cell infiltrate with occasional hair shaft necrosis. In the liver there was a periportal mononuclear cell infiltrate, and in the gut there was intense submucosal inflammation and a leucocytoclastic vasculitis accompanied in places by mucosal ulceration. Lewis rats (which are not prone to mercury-induced autoimmunity) showed no such changes after receiving HgCl2, nor did control BN rats given saline. BN rats pretreated with broad spectrum antimicrobial agents and then given HgCl2 showed milder histologic abnormalities, although antimicrobial treatment did not affect the antiglomerular basement membrane autoantibody response. CONCLUSIONS: We have identified a syndrome induced by mercuric chloride in BN rats in which there is evidence of tissue injury in many organs, with some features in common with graft-versus-host disease. There is also necrotizing leucocytoclastic vasculitis affecting the gut, and the importance of this is enhanced by the description in the accompanying paper of autoantibodies similar to those found in human systemic vasculitis. Our observations strengthen the analogies between this model and human autoimmune disease.

Animals↗
PubMed1991

Effects of ancrod and rtPA on fibrin accumulation, glomerular inflammation and renal function in nephrotoxic nephritis.

We have compared the effects of ancrod and recombinant tissue plasminogen activator (rtPA) on nephrotoxic nephritis induced in pre-immunized rabbits by the administration of nephrotoxic globulin (NTG; sheep anti-rabbit glomerular basement membrane). We used three different doses of NTG: in each experiment three groups of six rabbits were preimmunized with normal sheep globulin and given NTG: group A received no further treatment; group B received rtPA, 2 mg/kg 12 hourly; group C received ancrod 2 U/kg 12 hourly. Animals were bled daily for estimation of plasma fibrinogen and serum creatinine, then killed on day 5 and kidneys removed for histology. 1 ml/kg of NTG caused massive glomerular necrosis, all three groups having severe renal failure. With 0.5 ml/kg of NTG, ancrod and rtPA both effectively prevented fibrin deposition in Bowman's space, but all animals had severe proliferative glomerulonephritis and marked renal failure. With 0.25 ml/kg of NTG, control animals developed severe proliferative nephritis and advanced renal failure, ancrod provided almost complete protection, and the rtPA group had renal injury and functional impairment intermediate between the other two groups. We conclude that renal failure in severe nephrotoxic nephritis is fibrin-independent, but in less fulminant nephritis renal function can be protected by defibrination with ancrod. rtPA is capable of reducing glomerular fibrin accumulation as effectively as ancrod, but provides inferior protection of renal function.

Ancrod↗
PubMed1990

Severe hypertension after liver transplantation in alpha 1 antitrypsin deficiency.

Five children with alpha 1 antitrypsin deficiency and terminal liver disease received liver grafts; all five became hypertensive and four developed hypertensive encephalopathy. There was evidence of renal disease preoperatively and renal biopsy specimens showed variable glomerulonephritic histology with IgA nephropathy in one, mesangial-proliferative changes in two, and mesangio-capillary glomerulonephritis type I in two. Four hypertensive episodes were preceded by a fall in creatinine clearance. The association of glomerulonephritis with alpha 1 antitrypsin deficiency in children is more common than has been recognised. Affected patients are prone to severe hypertension of probable renal origin after liver transplantation and the renal lesion may affect long term prognosis.

Adolescent↗
PubMed1990

Abnormal fucosylation of ileal mucus in cystic fibrosis: I. A histochemical study using peroxidase labelled lectins.

Peroxidase conjugated lectins were used to analyse the glycoproteins of small intestinal mucins in normal infants and those with cystic fibrosis to ascertain whether there are any detectable histochemical differences in saccharide composition. A significant decrease in Lotus tetragonolobus (LTG) binding fucose was shown in normal small intestinal mucin starting around 36 weeks' gestation with total absence of staining at term and beyond. In contrast, the age matched patients with cystic fibrosis showed persistent and intense LTG binding of fucose. These results provide the first clear histochemical evidence that cystic fibrosis mucin is abnormal and confirm the findings of previous biochemical studies.

Cystic Fibrosis↗
PubMed1990

Abnormal fucosylation of-ileal mucus in cystic fibrosis: II. A histochemical study using monoclonal antibodies to fucosyl oligosaccharides.

Abnormal fucosylation of cystic fibrosis mucin was previously shown using peroxidase conjugated lectins on ileal tissue sections. These abnormally fucosylated glycoproteins were investigated further using monoclonal antibodies to fucosyl oligosaccharides based on type 1 and type 2 blood group precursor chains. The results of this study, using monoclonal antibodies to blood group glycoproteins in cystic fibrosis, were negative, yet abnormal fucosylation had been found using lectin histochemistry. Using monoclonal antibodies, lectins, and appropriate enzymes, such as glycosyl hydrolases, it should be possible to delineate further the abnormality found in glycoproteins in cystic fibrosis on appropriately fixed ileal sections, obtained from infants at term presenting with meconium ileus.

Antibodies, Monoclonal↗
PubMed1989

Campath-1M--prophylactic use after kidney transplantation. A randomized controlled clinical trial.

Campath-1M is a rat monoclonal IgM antibody that binds human complement and recognizes virtually all peripheral human mononuclear cells. It is known to be effective in T cell depletion of bone marrow grafts, and encouraging results were obtained in a pilot study in which the antibody was used in prevention and treatment of rejection of kidney, pancreas, and liver allografts. In this randomized controlled clinical trial, Campath-1M has been evaluated as a prophylactic agent following renal allografting. It is shown that patients who received a 10-day course of the antibody immediately postoperatively, in addition to standard therapy with high-dose cyclosporine (17 mg/kg), experienced a significantly lower incidence of early acute cellular rejection than control patients who received cyclosporine alone. There was no evidence of "rebound" rejection following the end of antibody treatment to suggest that rejection had merely been delayed. However, patients who received this additional immunosuppression experienced a significantly higher incidence of serious infections than controls, this negating any benefit from the treatment in terms of graft survival. Thus, a monoclonal antibody of broad specificity directed against lymphocytes may be effective as a prophylactic agent after organ transplantation but its use should be accompanied by a reduction in other immunosuppressive drugs.

Antibodies, Monoclonal↗