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Biomedical subjects

S G Wright

Publications and source records attributed to S G Wright.

At least 19 recordsLinked to original sources

Giardiasis.

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Antibody Formation

Anaemia in infancy.

Anaemia in infancy is a very common clinical problem in the tropics and will continue to be common while infectious disease and poor nutrition prevail. In the diagnosis of anaemia in a child the clinician must expect a number of factors to be involved. On the basis of clinical features it is possible to arrive at a working diagnosis that provides a basis for treatment. Genetically determined abnormalities of haemoglobin, haemoglobin synthesis and red cell enzymes are common in the tropics. Though laboratory tests are required to confirm their presence these conditions can be suspected clinically and often managed without laboratory facilities.

Anemia

Bacterial colonization of jejunal mucosa in giardiasis.

Nine of 14 cases of giardiasis and severe malabsorption were found to have numerous bacteria adjacent to the mucosa and within luminal fluid samples from the upper jejunum. Three species of enterobacteria (Klebsiella pneumoniae, Enterobacter cloacae and E. hafniae) were cultured from eight patients and from only one were Bacteroides isolated. Enterobacteria were not cultured from seven of eight patients who had giardiasis but only mild malabsorption (of xylose only) nor from seven patients without malabsorption. Intestinal colonization by enterobacteria may make an important contribution to the development of malabsorption in patients with giardiasis.

Enterobacteriaceae

Assessment of early and delayed responses in vitamin B12 absorption during antibiotic therapy in tropical malabsorption.

1. Vitamin B12 absorption was measured in 18 patients with tropical malabsorption. 2. Absorption was particularly impaired in patients with severe mucosal lesions. 3. Sequential measurements with 57Co- and 58Co-labelled vitamin B12 were made before and 48 h after the start of tetracycline therapy. A rapid improvement (on average 22% increase in absorption) occurred in four of six patients with marked mucosal lesions. Further improvement occurred in four of five patients measured after 4 weeks' tetracycline, including the two who failed to improve initially. 4. These rapid changes in vitamin B12 absorption after antibiotics occur too early to be due to mucosal recovery and suggest that bacterial metabolism is an important factor in the malabsorption in these patients.

Adult

Quantitative histology in giardiasis.

The Weibel graticule was used to assess quantitatively histological changes in proximal jejunal mucosal biopsies from patients with Giardia lamblia infections. Most had malabsorption. A group of patients who had mild abdominal symptoms but no intestinal infection and normal absorption were the controls. There were significant differences in mean surface area (SA) measurements between patients with giardiasis and severe malabsorption and controls (P less than 0.001) and infected patients with normal absorption (P less than 0.05). SA measurements correlated significantly with D-xylose excretion results (r = 0.55; P less than 0.01) and daily facal fat output (r = -0.61; P less than 0.001). Significant correlations between duration of symptoms and SA measurements (r = 0.43; P less than 0.05) and D-xylose excretion (r = 0.43; P less than 0.05) in giardiasis suggest that histological and functional impairment are maximal soon after infection and resolve in time. Treatment with metronidazole or mepacrine was associated with a significant increase in SA (P less than 0.05) in patients with severe malabsorption but there was little change in SA in a similar group of patients who received tetracycline. The Weibel graticule was found to be useful in assessing the severity of histological changes and in following changes after treatment.

Dietary Fats

Giardiasis.

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Feces

Giardiasis: clinical and therapeutic aspects.

Malabsorption was present in 29 of 40 symptomatic patients with giardiasis. Twenty-three had impaired D-xylose absorption; in 20 vitamin B12 absorption was low, and 15 patients had steatorrhoea. More severe malabsorption was associated with more marked histological abnormalities. Metronidazole, 2-0 g as a single daily dose on three successive days, produced a parasitological cure rate of 91%. In contrast, the standard course of mepacrine, 100 mg thrice daily for 10 days, eradicated the parasite in only 63% of patients. Improvements in absorption and jejunal morphology followed anti-giardial treatment. Tetracycline in eight patients failed to eradicate the parasite, intestinal absorption was unaltered, and histological appearances of the jejunal mucosa often deteriorated.

Adult

Quantification of the lymphocytic infiltrate in jejunal epithelium in giardiasis.

The intraepithelial lymphocytes of the jejunal mucosa from patients with giardiasis and from control patients were counted in coded serial sections. Patients with giardiasis and normal intestinal absorption and control patients who had lived and travelled in tropical areas had similar counts, which were higher than those reported for controls from temperate areas. Where giardiasis was accompanied by malabsorption of one substance the mean count was significantly higher than that of controls (P less than 0.02). In those patients with giardiasis and malabsorption of two or three substances the mean count was significantly higher than that of controls (P less than 0.02) and that of patients with giardiasis and normal absorption (P less than 0.05). After treatment, intraepithelial lymphocyte counts declined consistently in patients with malabsorption. An association between raised intraepithelial lymphocyte counts and malabsorption is indicated. The possible significance of this finding is discussed.

Adult