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Biomedical subjects

Y R Mahida

Publications and source records attributed to Y R Mahida.

At least 19 recordsLinked to original sources
PubMed1992

Therapeutic interventions in gastrointestinal disease based on an understanding of inflammatory mediators.

Whatever initiates inflammation, the final message mediating cellular invasion is chemical. This consideration allows rational development of anti-inflammatory treatments. Two main classes of chemotactic mediator are recognised. Water-soluble peptides, e.g. cytokines derived from macrophages and other cells, play an important integrating part in the early recruitment of neutrophils and mononuclear cells, and in the amplification of immune responses. Lipid-soluble mediators, of which leukotriene B4 is the most highly chemotactic for neutrophils, are important in secondary amplification. In inflammatory bowel disease, we have shown evidence of increased synthesis of cytokines interleukin 1, 6 and 8. These are associated with activation of circulating monocytes in active Crohn's disease, of lamina propria macrophages in relapse of both ulcerative colitis and Crohn's disease, and development of adhesion molecules on vascular endothelium. Our studies show that interleukin 6 is selectively increased in Crohn's disease, whilst preliminary findings suggest that enhanced synthesis of interleukin 8 is particularly characteristic of ulcerative colitis. Patterns of cytokine synthesis may, therefore, be of diagnostic value. They also offer the potential for therapeutic strategies since cytokine antagonists are becoming available. We have also demonstrated increased synthesis of leukotrienes in active inflammatory bowel disease. Since leukotriene B4 is quantitatively the main chemotactic signal in the mucosa in inflammatory bowel disease during relapse, we investigated the therapeutic effect of suppressing leukotriene B4 synthesis by treating patients with fish oil (as Hi-EPA), giving 4.5 g daily of eicosapentaenoic acid. This competes for the 5-lipoxygenase enzymes, inhibiting leukotriene B4 and promoting synthesis of the less chemotactic product, LTB5.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminosalicylic Acids↗
PubMed1992

Enhanced synthesis of neutrophil-activating peptide-1/interleukin-8 in active ulcerative colitis.

1. We studied neutrophil-activating peptide-1/interleukin-8 in inflammatory bowel disease. 2. Mucosal levels of neutrophil-activating peptide-1/interleukin-8 were significantly higher in patients with active ulcerative colitis [median 74.5 (range 17.7-450.8) pg/mg] than in patients with active Crohn's disease [10.4 (4-46.9) pg/mg; P less than 0.002] or in normal control subjects [10.4 (4-16.6) pg/mg; P less than 0.002]. 3. Circulating neutrophil-activating peptide-1/interleukin-8 was generally undetectable but there were higher levels of anti-neutrophil-activating peptide-1/interleukin-8 antibodies in patients with active ulcerative colitis [62.9 (3.4-239) ng/ml] than in patients with active Crohn's disease [5.9 (2.1-18.10) ng/ml; P less than 0.001] or in control subjects [6.1 (3.2-15.8) ng/ml; P less than 0.001]. 4. Neutrophil-activating peptide-1/interleukin-8 may be of specific functional importance in mediating inflammation in ulcerative colitis.

Antibodies↗
PubMed1992

Monoclonal antigranulocyte antibody imaging in inflammatory bowel disease: a preliminary report.

The 99Tcm-labelled antigranulocyte antibody BW250/183 has been used in the detection of intestinal inflammation in patients with active ulcerative colitis and Crohn's disease. Planar images were obtained up to 24 h after intravenous injection of the antibody. Eight out of nine patients with ulcerative colitis and six out of seven patients with Crohn's disease gave positive images. In 11 patients distribution of the inflammation was confirmed by barium studies, colonoscopy or surgery, whilst in two the antibody scan suggested more extensive disease than barium enema. None of the patients had any adverse reactions. Imaging with BW250/183 appears to give an accurate indication of the extent of inflammation in inflammatory bowel disease.

Colitis, Ulcerative↗
PubMed1992

Ranitidine: differential effects on gastric bleeding and mucosal damage induced by aspirin.

This study investigated the influence of ranitidine on mucosal injury and gastric bleeding in 20 normal volunteers taking 600 mg aspirin q.d.s. This study was a double-blind placebo controlled crossover study comparing ranitidine, as 150 mg b.d., 300 mg q.d.s. and 600 mg b.d. with placebo. Gastric mucosal injury was assessed at unsedated endoscopy by counting haemorrhagic and non-haemorrhagic erosions; bleeding was measured in gastric washings. Aspirin alone increased mucosal injury from 0 to 11.4 erosions (mean, P < 0.01) and bleeding from 1.77 to 9.11 microliters blood/10 min (mean P < 0.001). Ranitidine prophylaxis reduced bleeding to 5.34, 3.18 and 3.47 microliters/10 min with 150 mg b.d., 300 mg q.d.s. and 600 mg b.d. respectively (overall effect of ranitidine P < 0.001) and also reduced haemorrhagic erosions though it had no effect on the total number of erosions. Ranitidine is effective at reducing aspirin-induced gastric bleeding and whilst not reducing aspirin-induced gastric erosions, it does reduce the number that appear haemorrhagic. Ranitidine may have a role in the prophylaxis of aspirin-induced gastric bleeding.

Adult↗
PubMed1991

Two-color immunofluorescence and flow cytometric analysis of lamina propria lymphocyte subsets in ulcerative colitis and Crohn's disease.

By using two-color immunofluorescence with fluorescein isothiocyanate (FITC) and phycoerythrin (PE)-labelled monoclonal antibodies and multiparameter flow cytometry, we investigated lamina propria lymphocyte subsets of patients with ulcerative colitis (UC) and Crohn's disease (CD). Leu-3/Leu-2 (CD4/CD8) ratio of lamina propria lymphocytes (LPL) of CD (mean +/- SD: 1.9 +/- 0.8, P less than 0.01) was significantly decreased compared with controls (3.3 +/- 1.1), because of an increased number of CD8+ lymphocytes. The majority of lamina propria CD4+ cells were CD4+, Leu-8- and CD4+, CD45R- both in controls and IBD tissue. Many lamina propria T lymphocytes were activated, expressing HLA-DR antigen not only in IBD but also in controls. NK cells defined by CD16 and CD 56 (3.0 +/- 1.4%, P less than 0.01) were significantly decreased in patients with UC compared with controls (6.5 +/- 3.0%). A low proportion of B cells in the intestinal mucosa expressed Leu-8 antigen and CD23 antigen. The proportion of activated B cells of LPL was high in IBD mucosa as well as normal mucosa. These findings suggest that local activation of B cells leads to the loss of the expression of Leu-8 antigen and CD23.

Adolescent↗
PubMed1991

Separation of the impairment of haemostasis by aspirin from mucosal injury in the human stomach.

1. An increasing body of data suggests that the antihaemostatic as well as the ulcerogenic actions of aspirin and other non-steroidal anti-inflammatory drugs may be operative when patients present with haematemesis and melaena. 2. We therefore developed methods to allow separate evaluation of the erosive and anti-haemostatic actions of aspirin in the human gastric mucosa. Volunteer subjects took 300 mg of aspirin daily in the morning or 600 mg of aspirin four times a day for 5 days under blinded randomized conditions. Changes in spontaneous gastric microbleeding, endoscopic signs of injury, spontaneous bleeding per gastric erosion, biopsy-induced bleeding and eicosanoids were studied. 3. Both doses of aspirin significantly inhibited gastric mucosal synthesis of prostaglandin E2 and reduced the serum thromboxane concentration. Erosions developed and regressed rapidly; compared with baseline 300 mg of aspirin daily in the morning caused substantial numbers of gastric erosions to develop (mean 5.3, 95% confidence limits 2.7-10.2) but this was significantly less than that caused by 600 mg of aspirin four times a day (10.9, 7.2-16.5, P less than 0.05). The presence of erosions was associated with enhanced spontaneous bleeding, but only during aspirin administration. 4. Aspirin significantly increased bleeding induced by mucosal biopsy and was associated with significant enhancements in the rate of bleeding per gastric erosion. Bleeding rate per erosion but not biopsy-induced bleeding showed a significant dose-related increase with 600 mg of aspirin four times a day. Enteric coating reduced endoscopic signs of injury, but did not affect the impaired haemostasis caused by aspirin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Aspirin-induced gastric mucosal damage: prevention by enteric-coating and relation to prostaglandin synthesis.

1. Gastric damage induced by low-dose aspirin and the protective effect of enteric-coating was assessed in healthy volunteers in a double-blind placebo-controlled cross-over trial using Latin square design. Each was administered placebo, plain aspirin 300 mg daily, plain aspirin 600 mg four times daily, enteric-coated aspirin 300 mg daily, or enteric-coated aspirin 600 mg four times daily for 5 days. Gastric damage was assessed endoscopically, and gastric mucosal bleeding measured. 2. Aspirin 300 mg daily and 600 mg four times daily caused significant increases in gastric injury compared with placebo. Gastric mucosal bleeding was significantly more with the high dose, with a trend towards increased gastric erosions, compared with the low dose. 3. Enteric-coating of aspirin eliminated the injury caused by low dose aspirin and substantially reduced that caused by the higher dose. 4. All dosages and formulations caused similar inhibition of gastric mucosal prostaglandin E2 synthesis. 5. Serum thromboxane levels were suppressed equally with plain and enteric-coated aspirin. 6. In this short-term study in healthy volunteers, gastric toxicity from aspirin was largely topical, independent of inhibition of prostaglandin synthesis, and could be virtually eliminated by the use of an enteric-coated preparation.

Adult↗
PubMed1991

5-Aminosalicylic acid is a potent inhibitor of interleukin 1 beta production in organ culture of colonic biopsy specimens from patients with inflammatory bowel disease.

Interleukin 1 beta in biopsy specimens from inflamed colonic mucosa of patients with active inflammatory bowel disease was studied. Compared with normal colonic mucosal biopsy specimens, a significantly greater amount of interleukin 1 beta was present in rectal mucosa before (median (range) 4.3 (2.0-11.8) v 119.2 (30.1-286.8) pg/mg; p less than 0.01) and produced during organ culture (39.1 (9.4-106.8) v 97.6 (28.2-991.6) pg/mg; p less than 0.01). Values of interleukin 1 beta after culture correlated with concentrations of thromboxane B2. Organ culture of inflamed biopsy specimens in the presence of 5 aminosalicylic acid and dexamethasone reduced the amount of interleukin 1 beta detected. At the doses studied, 5 aminosalicylic acid also reduced the amount of leukotriene B4 detected after culture.

Adult↗
PubMed1991

High circulating concentrations of interleukin-6 in active Crohn's disease but not ulcerative colitis.

Peripheral venous plasma concentrations of interleukin-6 were studied in 21 patients with active Crohn's disease, 20 patients with ulcerative colitis, and 16 control subjects. Interleukin-6 was detected in the plasma of 18 of 21 patients with Crohn's disease (median 47 (range less than 20-250) pg/ml) but in only two with ulcerative colitis and two control subjects. In the patients with Crohn's disease there was a significant negative correlation between the plasma interleukin-6 and the serum albumin concentrations. In eight patients with Crohn's disease and five patients with ulcerative colitis undergoing resection plasma from peripheral circulation and mesenteric vein draining diseased intestine was studied. Interleukin-6 was detected in seven of eight peripheral and mesenteric samples from the patients with Crohn's disease but was not detected in any of the samples from the patients with ulcerative colitis. There was no significant difference between mesenteric and peripheral samples in the concentrations of interleukin-6.

Adolescent↗
PubMed1991

Coexpression of CD4 and CD8 on peripheral blood T cells and lamina propria T cells in inflammatory bowel disease by two colour immunofluorescence and flow cytometric analysis.

Using two colour immunofluorescence with fluorescein isothiocyanate and phycoerythrin labelled monoclonal antibodies and multiparameter flow cytometry, we investigated the coexpression of CD4 and CD8 antigens on peripheral blood lymphocytes and lamina propria lymphocytes of patients with ulcerative colitis and Crohn's disease and normal control subjects. Both the absolute number and the proportion of peripheral blood CD4+, CD8+ cells in inflammatory bowel disease were small but significantly increased compared with those in normal control subjects. Peripheral blood lymphocytes activated with phytohaemagglutinin showed appreciably increased coexpression of CD4+, CD8+. These CD4, CD8 positive cells were large and granular. Thus the increased number of peripheral blood CD4+, CD8+ cells in inflammatory bowel disease suggests that chronic immune activation occurs not only in the active state of the disease but also in remission. The proportion of CD4+, CD8+ cells in the lamina propria was greater than in peripheral blood in normal subjects, suggesting chronic immune stimulation of the local immune system. This was also seen in patients with Crohn's disease or inactive ulcerative colitis. The proportion of CD4+, CD8+ cells was, however, significantly less in the lamina propria of patients with active ulcerative colitis. Whether this implies a possible defect in mucosal immunoregulation in active ulcerative colitis cannot be determined from these results.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1990

Effect of human intestinal macrophages on immunoglobulin production by human intestinal mononuclear cells isolated from patients with inflammatory bowel disease.

The effect of macrophages on spontaneous immunoglobulin production by isolated human intestinal mononuclear cells (MNC) is unknown. Depletion of macrophages by adherence to fibronectin or by panning with macrophage-specific monoclonal antibody 3C10 lead to a significant reduction in IgA. IgG and IgM production by intestinal MNC from both normal (n = 10) and inflammatory bowel disease (IBD) (n = 13) mucosa. The reduction in immunoglobulin produced by macrophage-depleted intestinal MNC was greater in IBD patients than in normal controls. There was a significant correlation (r = 0.816, P less than 0.001) between the percentage of macrophages depleted by panning with 3C10 and the reduction in IgG produced by macrophage-depleted intestinal MNC. Addition of either fibronectin-adherent cells or the supernatant from these macrophage-enriched cells enhanced immunoglobulin production in a dose-dependent fashion. A greater increase in IgG production by macrophage-depleted cells was seen when cultured with supernatant from inflamed IBD mucosal cells, compared with that from normal mucosal cells. The soluble factor(s) responsible in the supernatant was acid and heat susceptible but was not affected by freezing and thawing. Addition of recombinant human interleukin-1 beta or human interferon-gamma to cell cultures did not influence immunoglobulin production. Thus, human intestinal macrophages enhance spontaneous immunoglobulin production by isolated intestinal MNC by secreting soluble factor(s) which remain to be fully characterized.

Cell Communication↗
PubMed1990

Plasma and tissue interleukin-2 receptor levels in inflammatory bowel disease.

Plasma and tissue interleukin-2 receptor (IL-2R) levels were determined in patients with active ulcerative colitis and Crohn's disease. Compared with healthy controls (median 440 U/ml; range 240-900), significantly higher levels of plasma IL-2R were present in patients with active ulcerative colitis (median 1180 U/ml; range 580-7150; P less than 0.002) and Crohn's disease (median 1340 U/ml; range 480-9000; P less than 0.002). Compared with other laboratory parameters, plasma IL-2R levels were related most closely to clinical score of disease activity in Crohn's disease. Plasma IL-2R levels also reflected the clinical course and may provide a more accurate assessment of disease activity in Crohn's disease. In plasma of patients undergoing intestinal resection of active inflammatory bowel disease, raised levels of IL-2R were present in samples from mesenteric vein (draining inflamed intestine) compared with those from peripheral vein. In tissue homogenates of colonic biopsies, significantly higher levels of IL-2R were present in specimens from colons with active ulcerative colitis compared with healthy controls (median 230.2, range 20.7-581.5 versus 77.9, range 34.2-291.3; P less than 0.02).

Biopsy↗
PubMed1990

Slow-release 5-amino-salicylic acid (Pentasa) for the treatment of active Crohn's disease.

A double-blind, placebo-controlled trial of a slow-release preparation of 5-amino-salicylic acid (Pentasa) has been performed in 40 patients with active Crohn's disease. Over a 6-week period, Pentasa (1.5 g daily) was no different to the dummy tablet in terms of clinical activity (Harvey-Bradshaw Index) or laboratory indicators of inflammation. No serious adverse reactions occurred.

Adult↗