Biomedical subjects

I N Ross

Publications and source records attributed to I N Ross.

27 records · Page 2Linked to original sources

PubMed1982

Demonstration of a pH gradient across the mucus layer on the surface of human gastric mucosa in vitro.

In previous studies we have demonstrated a hydrogen ion concentration gradient across the mucus on rat and rabbit fundic mucosa, in vivo and in vitro respectively, observations which support the possibility of a 'mucus-bicarbonate' protective barrier. In the present studies we have demonstrated a similar gradient across the mucus on human gastric mucosa in vitro. The minimum mean hydrogen ion concentration at the mucus-epithelium interface was 1 . 1 X 10(-4) mM (pH 6 . 96, n = 10) when the luminal concentration was 5 . 6 mM (pH 2 . 25). Aspirin (10 mM) and N-acetyl cysteine (306 mM) (5%) increased the minimum intra-mucus hydrogen ion concentration and the gradient was overwhelmed by a luminal hydrogen ion concentration of 40 mM (pH 1 . 4). These results suggest that a hydrogen ion concentration gradient exists across the mucus on human gastric mucosa and that potential damaging agents may act by compromising one or other of th components of this 'mucus-alkaline', presumed 'mucus-bicarbonate', barrier.

Aspirin↗

PubMed1981

One-hour serum xylose as an absorption test in the tropics.

The 1-hour serum xylose (surface area corrected) as an indication of xylose absorption after 5 g oral D-xylose has been compared with the 5-hour urine excretion test in a tropical population. The study confirmed that the peak serum xylose concentration occurs at 1 hour and that correction to a constant body surface are improves the discrimination between subjects with normal and impaired xylose absorption. The significantly lower reference range for the 1-hour surface area corrected serum xylose (0.55-1.11 mmol/l) compared to the UK figure reflects the reduced absorptive capacity of the jejunum, a result of tropical enteropathy. In view of the difficulties in obtaining accurate urine collections in tropical countries, especially in field studies, it is recommended that the 1-hour serum xylose (surface area corrected) should be adopted as the standard test of xylose absorption.

Body Surface Area↗

PubMed1981

The pH gradient across mucus adherent to rat fundic mucosa in vivo and the effect of potential damaging agents.

We investigated the possibility that a "mucus-bicarbonate" barrier might exist in the stomach in vivo. Using an antimony microelectrode a pH gradient was demonstrated across the mucus layer on the fundic mucosa of the rat stomach in vivo. When the luminal pH was 2.0 the maximum pH reached on traversing the mucus layer was 6.68 +/- 0.71 (n = 30) and a stable gradient could be maintained across the mucus for over 100 min. Introduction of luminal solutions with a pH of less than 1.5 caused a fall in the pH gradient and its abolition at pH 1.2. N-Acetyl-L-cysteine (5%) in pH 2.0 luminal HCl solution caused a fall in pH in 12 of 18 rats within 5 min. After 30 to 60 min exposure the maximum mean pH in 12 rats was reduced to 4.18 +/- 0.92 (p less than 0.001). Ten millimolar aspirin in pH 2.0 HCl also caused a fall in pH in 12 of 24 rats within 10 min and the maximum pH in 12 rats after 30-60 min exposure was 4.13 +/- 0.84 (p less than 0.001). These effects on the mucus pH gradient were local actions because in other, untreated areas of the same stomachs there was a normal maximum pH. Ten millimolar sodium taurocholate in pH 2.0 HCl produced a visible clouding of the mucus layer, but no fall in pH. However, gentle manipulation caused the mucus to "flake" off with a subsequent fall in underlying pH. These observations indicate the presence of a pH gradient in mucus in vivo which can be compromised by agents which interfere with mucus structure and/or bicarbonate secretion and by high intraluminal hydrogen ion concentrations. The results support a role for this barrier in gastric mucosal protection.

Acetylcysteine↗

PubMed1981

Immunological changes in tropical sprue.

Immunological measurements in 85 southern Indian patients with tropical sprue were compared with two groups of controls, namely, 150 patients with gastrointestinal diseases not associated with malabsorption, and 57 normal asymptomatic subjects. A significant increase in intraepithelial lymphocytes in jejunal surface and crypt epithelium, related to the severity of the mucosal morphological abnormality, was the most significant finding in tropical sprue. Measurements such as increased serum concentrations of IgG, IgE, complement component C4 and orosomucoid, gastric parietal cell antibodies and lymphopaenia with a low peripheral blood T cell count, which were found in patients with sprue, differed significantly from the healthy control group but not from the group of gastrointestinal controls without malabsorption. The ability to produce functional antibodies was preserved in tropical sprue. The results suggest that the small intestinal enterocyte abnormality in tropical sprue is not the result of a primary immunological process but that the observed alterations are a sequelae of mucosal damage and compromised integrity of the mucosal barrier.

Adolescent↗

PubMed1979

Significance of serum complement levels in patients with gastrointestinal disease.

Levels of the serum complement components, C3 and C4, in patients with Crohn's disease, ulcerative colitis, and miscellaneous gastrointestinal disorders were compared with those of normal blood donors. Significant increases of both components were found in all three patient groups, the highest being in patients with Crohn's disease. Generally, levels of C3 and C4 were lower in patients with inactive rather than active Crohn's disease and ulcerative colitis. These results provide some evidence in support of an immunological basis for inflammatory bowel disease. However, in view of the frequent elevation of C3 and C4 in other gastrointestinal diseases, it is equally possible that the complement components are behaving as acute phase proteins.

Blood Donors↗

PubMed1978

Whipple's disease in a female with impaired cell-mediated immunity unresponsive to co-trimoxazole and levamisole therapy.

A case of Whipple's disease in a female is described. Malabsorption of iron, vitamin B12, folic acid and fat was present. These abnormalities reverted to normal after introduction of co-trimoxazole therapy. The patient's humoral immune system was normal, in contrast to impairment of cell-mediated immunity, which has not improved in spite of co-trimoxazole treatment for 2 years, and a therapeutic trial of levamisole. These findings are further evidence that there may be a primary immune deficiency in patients with Whipple's disease.

Drug Combinations↗

PubMed1978

The ageing gut: a study of intestinal absorption in relation to nutrition in the elderly.

This study was designed to assess the functional efficiency of the ageing small intestine and the possible role of malabsorption in old people with nutritional deficiencies. Fifty subjects aged 65 to 92 years were studied, of whom 33 presented with anaemia, chronic diarrhoea or bone pains, and 17 were apparently healthy 'controls' with no relevant symptoms. Tests of intestinal function included blood xylose and iron absorption curves, a double isotope Schilling test, faecal fat, urinary indican and small bowel radiology, with duodenal aspiration and jejunal biopsy in some cases. On the basis either of steatorrhoea or at least two other abnormal parameters of absorption, there were 15 cases of malabsorption. Thirteen of these had symptoms but two were 'controls'. Four of these had duodenal diverticulosis, two had the post-gastrectomy syndrome, and one had calcific pancreatitis. Malabsorption in the remaining eight cases was not fully explained. The age range of this last group was 72--86 years; one of them had a contaminated small bowel and two showed some evidence of pancreatic insufficiency. Malabsorption emerged as a significant cause of low levels of serum iron, haemoglobin and calcium. The blood xylose test is a useful screening procedure for intestinal malabsorption in old age, but full evaluation calls for investigation of pancreatic function.

Aged↗

PubMed1977

IgG myeloma presenting as ulcerative colitis.

Two patients who presented with ulcerative colitis are described. Both were found to have evidence of IgG monoclonal gammopathy and Bence-Jones proteinuria. This association has been reported previously only in the presence of myelomatous infiltration of the gastrointestinal tract or in amyloidosis, and hence the cases reported appear to be unique.

Bence Jones Protein↗

PubMed1976

Severe selective IgM deficiency.

Among the primary antibody deficiency syndromes, severe selective IgM deficiency (also previously known as type V dysgammaglobulinaemia) is rare, and the majority of previous reports have indicated a fatal outcome. Three adult patients who were found to have a persistently low serum IgM are described. This deficiency was not obviously related to their presenting illness; in two of the patients, who were investigated in detail, it appeared to be of no immediate consequence.

Aged↗