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Biomedical subjects

J George

Publications and source records attributed to J George.

At least 181 records · Page 10Linked to original sources
PubMed1996

Heart valve involvement (Libman-Sacks endocarditis) in the antiphospholipid syndrome.

The antiphospholipid syndrome (APS) is defined by the presence of anti-phospholipid antibodies (aPLs) and venous or arterial thrombosis, recurrent pregnancy loss, or thrombocytopenia. The syndrome can be either primary or secondary to an underlying condition, most commonly systemic lupus erythematosus (SLE). Echocardiographic studies have disclosed heart valve abnormalities in about a third of patients with primary APS. SLE patients with aPLs have a higher prevalence of valvular involvement than those without these antibodies. Valvular lesions associated with aPLs occur as valve masses (nonbacterial vegetations) or thickening. These two morphological alterations can be combined and are thought to reflect the same pathological process. Both can be associated with valve dysfunction, although such association is much more common with the latter alteration. The predominant functional abnormality is regurgitation; stenosis is rare. The mitral valve is mainly affected, followed by the aortic valve. Valvular involvement usually does not cause clinical valvular disease. The presence of aPLs seems to further increase the risk for thromboembolic complications, mainly cerebrovascular, posed by valve lesions. Superadded bacterial endocarditis is rare but may be difficult to distinguish from pseudoinfective endocarditis. The current therapeutic guidelines are those for APS in general. Secondary antithrombotic prevention with long-term, high-intensity oral anticoagulation is advised. The efficacy of aspirin, either alone or in combination, is yet to be assessed. Corticosteroids are not beneficial and may even facilitate valve damage. Immunosuppressive agents should only be used for the treatment of an underlying condition. Current data suggest a role for aPLs in the pathogenesis of valvular lesions. aPLs may promote the formation of valve thrombi. These antibodies may also act by another mechanism, as indicated by the finding of subendothelial deposits of immunoglobulins, including anticardiolipin antibodies, and of colocalized complement components in deformed valves from patients with APS.

Antiphospholipid Syndrome↗
PubMed1996

Molecular characteristics of dimethylnitrosamine induced fibrotic liver collagen.

The molecular characteristics of purified pepsin solubilized collagen from rat liver was studied in control and dimethylnitrosamine administered animals. The alpha- and beta-chains of purified pepsin solubilized liver collagen were separated by subjecting the denatured collagen to SDS-polyacrylamide gel electrophoresis. The alpha 1(III) chains were resolved from the alpha 1(I) chains by interrupted electrophoresis with delayed reduction of the disulfide bonds of type III collagen. The aldehyde content of the purified pepsin solubilized collagen was estimated in control and experimental samples in order to assess the extent of collagen cross-links. Fibril formation curves were studied with purified pepsin solubilized collagen to see the rate of formation of cross-links within the fibrillar mesh. The results of the unreduced electrophoretic studies revealed a significant increase in the beta-subunit of type I collagen with a remarkable decrease of alpha/beta ratio in DMN treated animals. Reduction with beta-mercaptoethanol indicated the presence of type III collagen in the electrophoretic field with a proportionate increase on the 21st day. A significant increase in the aldehyde content and an increased rate of fibril formation were noticed in DMN induced fibrotic liver collagen. The data of the present investigation revealed that the DMN induced fibrotic liver collagen is more cross-linked than normal liver collagen and the deposition of type III collagen in more prominent than type I collagen in early fibrosis.

Animals↗
PubMed1996

Interferon gamma down-regulates cytochrome P450 3A genes in primary cultures of well-differentiated rat hepatocytes.

Administration of interferons of both the gamma and alfa/beta classes down-regulates hepatic cytochrome P450 (CYP) genes when administered to humans or rats. In male rats, interferons decrease expression of CYP3A2 at a pretranslational level, but because interferons also release other cytokines in vivo, it is unclear whether this is a direct effect on hepatocytes. We therefore examined the effects of rat recombinant interferon gamma (IFN-gamma) on CYP3A2, other 3A genes, and 2C11 in stable primary cultures of male rat hepatocytes. Hepatocytes were cultured on matrigel in Williams' E, and messenger RNAs (mRNAs) for 3A2, 3A1-like CYPs, and 2C11 mRNA were determined by RNase protection assays. CYP3A and 2C11 proteins were immunoquantified, and their catalytic activities were estimated by testosterone hydroxylation pathways. In control cells, 3A2 mRNA decreased initially but then recovered, and stable levels (15% of freshly isolated cells) were attained between days 3 and 7. Phenobarbital increased 3A2 mRNA to 60-120% values of freshly isolated cells, and mRNA for 3A1-like CYPs were increased 20-fold. In both control and phenobarbital-treated hepatocytes, rat recombinant IFN-gamma (33 U/mL) reduced mRNA for 3A2 and 3A1-like CYPs, as well as 3A protein and testosterone 6 beta-hydroxylase activity. Interferon had no effect on CYP2C11 at mRNA or protein levels in untreated cells, although a reduction in 2C11 protein was evident in phenobarbital-treated cultures. It is concluded that interferon directly alters expression of constitutive and inducible CYP3A genes in well-differentiated male rat hepatocytes in culture, but has no effect on constitutive expression of CYP2C11.

Animals↗
PubMed1996

Autoantibodies in black South Africans with systemic lupus erythematosus: spectrum and clinical associations.

The clinical features and autoantibody profile of 111 black South Africans (103 females and 8 males) with systemic lupus erythematosus were retrospectively analysed. The mean age of the patients was 35.1 years and mean duration of disease 3.5 years. The commonest clinical and laboratory features noted were arthritis (62.2%), hypocomplementaemia (61.2%), haematological abnormalities (60.5%) and malar rash (55%). The serological abnormalities included antinuclear antibodies (98.2%), anti-dsDNA (66.2%), anti-Sm (44.2%), anti-RNP (65.5%), anti-Ro (60.5%), anti-La (28.4%) and rheumatoid factor (10.1%). Positive clinicoserological associations observed included: combination of anti-dsDNA antibodies and low C4 levels with renal disease; anti-dsDNA antibodies with cutaneous vasculitis; anti-Sm antibodies with psychosis; anti-RNP antibodies with Raynaud's phenomenon; anti-Ro antibodies with renal disease, psychosis and malar rash. Anti-La antibodies showed a weak negative association with serositis and Raynaud's phenomenon. Most of these clinical correlates are consistent with past studies. The high frequency of anti-Sm and anti-RNP antibodies is similar to the observations in African-Americans and Afro-Caribbeans.

Adolescent↗
PubMed1996

Autoantibodies in black South Africans with systemic lupus erythematosus: spectrum and clinical associations.

The clinical features and autoantibody profile of 111 black South Africans (103 females and 8 males) with systemic lupus erythematosus was retrospectively analysed. The mean age of the patients was 35.1 years and mean duration of disease 3.5 years. The commonest clinical and laboratory features noted were arthritis (62.2%), hypocomplementaemia (61.2%), haematological abnormalities (60.5%) and malar rash (55%). The serological abnormalities included antinuclear antibodies (98.2%), anti-dsDNA (66.2%), anti-Sm (44.2%), anti-RNP (65.5%), anti-Ro (60.5%), anti-La (28.4%) and rheumatoid factor (10.1%). Positive clinicoserological associations observed included: combination of anti-dsDNA antibodies and low C4 levels with renal disease; anti-dsDNA antibodies with cutaneous vasculitis; anti-Sm antibodies with psychosis; anti-RNP antibodies with Raynaud's phenomenon; anti-Ro antibodies with renal disease, psychosis and malar rash. Anti-La antibodies showed a weak negative association with serositis and Raynaud's phenomenon. Most of these clinical correlates are consistent with past studies. The high frequency of anti-Sm and anti-RNP antibodies is similar to the observations in African-Americans and Afro-Caribbeans.

Adolescent↗
PubMed1996

Emerging cross-regulatory roles of immunity and autoimmunity in atherosclerosis.

Atherosclerosis is a histopathological process of a multifactorial origin. Whereas the genetic and biochemical causes received considerable attention, the involvement of the immune system has generally been considered negligible. In recent years evidence has been presented to support the dominant role played by the immune system in atherosclerosis. Two major antigenic determinants against which the immune response may be triggered have been suggested, namely the heat shock protein 60/65 and oxidized low density lipoprotein. The current paper reviews the data regarding the involvement of the immune system in atherogenesis with respect to the antigenic candidates mentioned above.

Arteriosclerosis↗
PubMed1996

Glycoprotein metabolism in dimethylnitrosamine induced hepatic fibrosis in rats.

Glycoproteins play a major role in the pathogenesis of hepatic fibrosis by accumulating in the sinusoids and the space of Disse. In order to obtain more information about the altered metabolism of glycoproteins during the development of human hepatic fibrosis, the carbohydrate moieties of the glycoproteins were monitored in experimentally induced hepatic fibrosis. The liver injury was induced by injecting dimethylnitrosamine intraperitoneally in male albino rats. The injections were given on the first 3 consecutive days of each week over a period of 21 days. Glycoprotein moieties such as total hexose, hexosamine, fucose and sialic acid were estimated in liver, serum and urine samples on days 7, 14 and 21 of the experiment. The results indicated a significant decrease in total hexose and an increase in fucose levels in the liver tissue during dimethylnitrosamine administration. While protein bound hexose in the serum showed a significant decrease, sialic acid levels were notably increased. The other glycoprotein moieties both in liver and serum also showed an increase in the later periods of study, especially on day 21. All glycoprotein moieties exhibited a significant increase in the rate of urinary excretion on the 14th and 21st days, indicating an increased rate of metabolic degradation in the acute phase of hepatic fibrosis. The results suggest that glycoproteins undergo changes in both synthesis and the degradation during hepatic fibrosis. The relative alterations in these processes will play a vital role in determining the progression of hepatic fibrosis.

Animals↗
PubMed1996

Severe Blastocystis hominis in an elderly man.

We describe a unique case of severe Blastocystis hominis infection in an elderly man with severe dehydration, marked leukocytosis and hypoalbuminaemia after antibiotic treatment for right pneumonia. The patient recovered after treatment with metronidazole. This case presentation demonstrates the ability of B. hominis to induce severe gastrointestinal manifestations and general deterioration, particularly in light of the controversy surrounding its possible potential pathogenicity. We believe, therefore that aggressive treatment with metronidazole should be instituted, following demonstration of the parasite in the stools, if diarrhoea is protracted, since it may well be attributed to Blastocystis infection.

Aged↗
PubMed1996

The effects of early and late administration of M-20 derived interleukin-1 inhibitor on experimental systemic lupus erythematosus.

M-20 interleukin-1 inhibitor is produced by a myelomonocytic cell line. The effects of this molecule, mediated via IL-1 inhibition, include decreased proliferative responses of mouse thymocytes, human T-cells and fibroblasts and reduction in parameters of acute inflammation. Previously, we have demonstrated the emergence of a disease resembling systemic lupus erythematosus (SLE) in naive mice immunized with anti-DNA antibodies carrying different pathogenic idiotypes. The disease was manifested by increased titers of various mouse antibodies, concomitant with the appearance of elevated erythrocyte sedimentation rate (ESR), proteinuria and leukopenia. We have applied this model of experimental SLE (immunized with MIV-7, a human monoclonal antibody) to evaluate the influence of M-20 IL-1 inhibitor, administered at different stages (2 weeks before, 1 month and 3 months following immunization) for a period of 2 weeks, on the findings of the disease in mice. It was shown that M-20 IL-1 inhibitor given 2 weeks prior to the immunization resulted in suppression of the disease induction as documented by lower antibody titer level (30%-50% in the immunized mice as compared with controls). Furthermore, reduced autoantibody levels were accompanied by other beneficial findings consisting of lower ESR, less severe proteinuria and elevated leukocyte counts. No beneficial effects of M-20 IL-1 inhibitor were observed when the agent was administered 1 or 3 months following immunization. We conclude that M-20 IL-1 inhibitor has a favorable effect on experimental SLE in mice, provided it is administered before induction of the disease.

Animals↗
PubMed1996

A question of bias.

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Case-Control Studies↗
PubMed1996

Influence of clinicopathological variables on CYP protein expression in human liver.

Drug metabolism is usually impaired in malnourished patients with decompensated cirrhosis, but the separate influence of clinicopathological variables, including nutritional status, on the expression of hepatic cytochrome P450 proteins has not been well characterized. We determined the hepatic content of CYP1A2, CYP2C8/10, CYP2E1 and CYP3A proteins in 71 subjects, 21 with histologically normal livers and 50 with chronic liver disease, and then tested for potential relationships between patient variables and individual CYP proteins by multivariate linear regression analysis. Variables analysed included nutritional status (determined by experienced clinicians), serum albumin and bilirubin concentrations, prothrombin time, the grade of ascites and hepatic encephalopathy, and the Child-Pugh score. Impaired nutrition and cachexia were associated with reductions of CYP2C8/10 levels of approximately 19 and 39%, respectively, relative to cases in which nutrition was replete. Similarly, CYP2E1 protein was reduced by approximately 13 and 26%, according to the apparent severity of nutritional impairment. In contrast, nutritional status did not contribute to variability in expression of CYP1A2 or CYP3A proteins. Of the clinicopathological variables analysed, only serum bilirubin was shown to have an independent influence on CYP protein content. Thus, elevated serum bilirubin concentrations were associated with significant declines in the contents of CYP1A2 and CYP2C8/10 but not CYP3A or CYP2E1. The mechanisms for the effects of nutritional status and serum bilirubin concentration on the levels of CYP proteins are unclear, but could be mediated by factors such as cytokines, dietary composition and alterations in the level of serum bile acids. Knowledge of the influence of clinicopathological factors and nutritional status on CYP expression should lead to more rational drug prescribing in patients with hepatic disease.

Bilirubin↗
PubMed1996

Renal functional reserve in kidney donors assessed in different settings using scintigraphy.

Glomerular filtration rate (GFR) was measured in 9 voluntary male kidney donors by scintigraphy. In the basal state, the mean GFR was 96.1 +/- 22 ml/min/1.73 m2. Four weeks after donor nephrectomy, the GFR of the remaining kidney had increased by 22.8 +/- 20.7% (p < 0.05). A protein meal given at this time failed to significantly augment the GFR. The GFR of the grafted kidney increased by 59.7 +/- 24.4% after 6 months (p < 0.01). Renal functional reserve was thus demonstrated in the remaining kidney and the allograft, though a further reserve could not be elicited in the remaining kidney.

Adult↗
PubMed1996

Guillain-Barré as an autoimmune disease.

Guillain-Barré syndrome (GBS) entails a demyelinating process of the peripheral nervous system. The etiopathogenesis of the syndrome is still a matter of debate although considerable progress has been accomplished in the recent years. Abundant evidence has been put forward so as to support the role of the immune system in initiating and perpetuating the ongoing damage culminating in the emergence of the clinically overt syndrome. As such, data on the involvement of the humoral immune pathways add to the information already presented with regard to cell-mediated mechanisms participating in disruption of peripheral nerve. The following review will focus on the current knowledge of these complex mechanisms and the relative significance of each in the pathogenesis of GBS.

Animals↗
PubMed1996

Modulation of experimental systemic lupus erythematosus with linomide.

OBJECTIVE: The objective of this study was to assess the beneficial effects of an early administration of low dose linomide, a new immunomodulator, in an animal model of experimental systemic lupus erythematosus (SLE). METHODS: Experimental SLE was induced in naive BALB/c mice, by immunization with anti-DNA mAb (MIV-7). Control Mice immunized with irrelevant human IgM served as controls. The immunized mice were treated with linomide (0.1 mg/ml in the drinking water), four weeks prior to the first immunization, at an early stage of the disease induction (one month after boost injection), or at a later stage (3 months following boost immunization). The treatment duration was 3 months in all schedules. The follow-up studies continued for 8 weeks after discontinuation of the treatment. The presence in the serum of autoantibodies against ssDNA, dsDNA histones, phospholipids and an irrelevant autoantigen-pyruvate dehydrogenase, was determined by enzyme-linked immunosorbent assay (ELISA). The clinical parameters assessed included erythrocyte sedimentation rate, peripheral blood cell counts and proteinuria. RESULTS: There was a 50-64% decrease in autoantibody levels in the sera of mice immunized with anti-DNA (MIV-7) mAb at the early stage of experimental SLE in mice which received linomide for a period of 3 months. No effect of linomide was noted in mice which received the drug during the later stages of experimental SLE when the disease was fully developed. Linomide had a preventive effect on the induction of experimental SLE in naive mice, when the treatment was initiated before the induction of the disease. This effect was abolished following cessation of the treatment. CONCLUSIONS: Linomide proved to be effective at the early stages of induction of the experimental SLE. However, the autoantibody levels rose following discontinuation of the therapy.

Adjuvants, Immunologic↗