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Biomedical subjects

W G Brydon

Publications and source records attributed to W G Brydon.

At least 37 records · Page 2Linked to original sources
PubMed1987

Absorbed dose from 14C xylose and 14C mannose.

Tissue distribution and excretion studies have been performed in rats and mice for up to 1 week after oral administration of 14C xylose and 14C mannose. The effective dose-equivalent is calculated to be 15 microSv/MBq for xylose and 120 microSv/MBq for mannose. Since there was no clearance of mannose during the period of the study, the effective dose-equivalent for mannose is almost entirely dependent upon the assumptions made about expected lifetime exposure.

Absorption↗
PubMed1987

Diagnosis of acute pancreatitis: a proposed sequence of biochemical investigations.

In 60 controls and 108 patients admitted with acute abdominal pain, Rapignost urinary amylase correctly identified (++) 18 of the 23 patients with acute pancreatitis (AP), with 8 results being equivocal (+), and 1 false negative. This is a suitable screening test for AP, but an equivocal result requires further investigation. In 14 patients with AP the serum amylase was over 1000 U/l with no false-positive results, whereas when 316 U/l was used as the diagnostic threshold, 22 cases were identified (but with 2 false positives). Serum lipase was 100% sensitive in the diagnosis of AP, but there were three false-positive results.

Acute Disease↗
PubMed1986

An experimental design to study colonic fibre fermentation in the rat: the duration of feeding.

1. The time-course of metabolic adaptation by rats to diets containing either wheat bran or gum arabic was studied during a 12-week period. 2. Stool weight was increased with wheat bran but not with gum arabic, and had stabilized after 4 weeks. 3. Bacterial mass as measured by diaminopimelic acid content had stabilized by week 4. Bacterial mass increased on feeding gum arabic but was unchanged with wheat bran. 4. There was increased caecal short-chain fatty acid, hydrogen and methane production with gum arabic but not with wheat bran. The change in caecal metabolic activity was slow to stabilize (8-12 weeks at least). 5. The faecal excretion of bile acids increased twofold with the wheat-bran-supplemented diet compared with the gum-arabic-supplemented and unsupplemented diets. Relatively greater amounts of muricholic acids were present in the caeca and faeces of gum-arabic-fed rats compared with the other groups.

Animals↗
PubMed1986

The effect of the polysaccharide composition and structure of dietary fibers on cecal fermentation and fecal excretion.

The fermentation of dietary fibers gives a clue to their mode of action. Wheat bran and gum tragacanth increase stool weight but have no effect on serum cholesterol or on hydrogen excretion. Gum arabic and pectin in the form of raw carrot have no effect on stool weight but decrease serum cholesterol and are associated with an increase in breath-hydrogen excretion. Other fiber sources like gum karaya have no effect on stool weight, serum cholesterol, or breath hydrogen. There are no correlations between the chemical composition and structure of the fibers studied and their physiological effects.

Breath Tests↗
PubMed1986

Intestinal gas formation and the use of breath measurements to monitor the influence of diet and disease.

With the development of sophisticated physiological and biochemical analytical techniques and intestinal gas analysis, both direct, e.g. Argon washout and indirect, e.g. breath measurements of H2 and labelled CO2 derived from intestinal metabolism, greater understanding of the influence of diet on intestinal gas production and the development of diagnostic procedures for identifying causes of malabsorption have evolved. The use of stable isotopes and different probe molecules will see even greater developments in this field in the years ahead.

Air↗
PubMed1985

The influence of creatinine, lecithin and choline feeding on aliphatic amine production and excretion in the rat.

The excretion of aliphatic amines, methylamine, dimethylamine and trimethylamine in the urine and faeces of rats fed on a control diet and diets supplemented with creatinine, lecithin or choline were measured over a 14 d feeding period. The rats were then killed and concentrations of amines in small and large intestinal contents measured. Adding creatinine to the diet resulted in a significant increase of methylamine excretion in the faeces and urine. The amount of methylamine found in all parts of the intestine increased, especially in the caecum. Adding lecithin to the diet resulted in an increase in the methylamine excretion only, and no change in the concentrations of amines found in the intestine, except for trimethylamine which was significantly increased in the caecum and colon. Adding choline to the diet resulted in a significant increase in excretion of trimethylamine and, to a lesser extent, methylamine. The levels of amines found in the gut increased, dimethylamine being increased in the small bowel, and methylamine and trimethylamine in the caecum.

Animals↗
PubMed1985

Methane excretion in man--a study of breath, flatus, and faeces.

In this paper aspects of the variability of methane producing status have been examined, and a survey of breath methane excretion in various clinical and control populations is reported. Prevalences of methane excretion were 54% in healthy controls, 53% in non-gastrointestinal patients and 32% in gastrointestinal patients. Patients with Crohn's disease, ulcerative colitis, and pneumatosis cystoides intestinalis had significantly lower prevalences of methane excretion (13%, 15%, and 11% respectively). Faecal constituents and in vitro incubation analysis were similar in breath methane excretors and non-excretors. Several patients did not excrete methane in the breath although methane was present in colonic gas. The results indicate that different gastrointestinal patient groups have different prevalences of breath methane excretion and that all healthy subjects may produce methane but only when the production reaches a threshold does it appear in the breath.

Adolescent↗
PubMed1984

The effects of dietary gum tragacanth in man.

Following a 7-day control period, 5 male volunteers consumed 9.9 g gum tragacanth (GT) daily for 21 days. The GT was well tolerated and there were no adverse effects in any of the volunteers. The daily intake was very high in relation to the minor amounts of GT (estimated at 2 g per person per annum) likely to be ingested as a foodstuffs additive. The wide range of measurements made before and at the end of the test period show that the ingestion of GT had no significant effect on any of the following: plasma biochemistry; haematological indices; urinalysis parameters; glucose tolerance; serum cholesterol, triglycerides and phospholipids; breath hydrogen and methane concentrations. The intestinal transit time decreased and faecal fat concentration increased (P less than 0.01) for 4 subjects. The faecal wet and dry weights increased in all subjects (P less than 0.01). These changes may be of nutritional and physiological interest but do not reflect any adverse toxicological effects arising from the ingestion of large daily doses of GT.

Adult↗
PubMed1984

A study of the effects of dietary gum arabic in the rat.

Gum arabic (GA) is a water-soluble polysaccharide (molecular weight approximately 850 000) containing rhamnose, arabinose, glucuronic acid and galactose. The metabolism of GA has been studied in the rat. Adult male Wistar rats were given GA incorporated into either an Oxoid breeders (OB) diet or an elemental (Elem) diet. Intestinal contents were examined for precipitable GA using acidified ethanol. GA was found from stomach to small intestine but not in the caecum, colon or rectum. Caecal excision and restoration of intestinal continuity resulted in GA recovery from stomach to rectum. Excreted methane, hydrogen and volatile fatty acids (VFA) were measured as indicators of bacterial activity in the caecum and colon. Methane excretion increased on the OB + GA diet and H2 concentrations remained unaltered. The Elem diet abolished gas production. When the animals were given the Elem + GA diet, H2 and methane were only produced after 28 d. Faecal VFA increased with increasing GA intake, acetate concentration increased and butyrate concentration decreased with increasing GA dosage. Significant decreases in concentrations of VFA were found from caecum to left colon and from left colon to faeces. It can be concluded that GA degradation occurs in the caecum and is associated with increased methane excretion, increased VFA concentrations and changes in the proportions of various VFA in the faeces.

Animals↗
PubMed1984

Fecal weight and composition, serum lipids, and diet among subjects aged 18 to 80 years not seeking health care.

Sixty-two subjects not seeking health care, aged 18 to 80 yr, recorded diet intake, collected feces for 7 days, and gave fasting blood lipids. There was a great variation in stool weight passed (19 to 278 g/24 h). Fecal constituents (bile acids, sterols, fat, electrolytes) correlated strongly with fecal mass. Fecal mass correlated inversely with transit time. There was no relationship between age and fecal weight or transit time. Multiple regression analysis showed that only dietary fiber contributed to stool weight. No single component of fiber appeared to be responsible for this relationship with stool mass. Multiple regression analysis of serum cholesterol showed a relationship only with age and fecal neutral sterols.

Adolescent↗
PubMed1984

Cellobiose/mannitol sugar permeability test complements biopsy histopathology in clinical investigation of the jejunum.

Intestinal permeability to probe molecules has been shown to correlate closely with the presence or absence of villous atrophy in a jejunal biopsy. The purpose of this study was to establish if there exist groups of patients with functional derangement of intestinal permeability but normal histopathology of the small bowel mucosa. In 135 patients a cellobiose/mannitol permeability test was performed at the same time as jejunal biopsy. Diagnosis included coeliac disease, Crohn's disease, irritable bowel syndrome, idiopathic diarrhoea, self diagnosed food allergy, atopic eczema and postinfectious malabsorption. The value of the cellobiose/mannitol test in identifying patients with abnormal jejunal biopsy histopathology was confirmed. The permeability test was abnormal in all 28 patients with partial or subtotal villous atrophy, and also in all 10 in whom there was a high intraepithelial lymphocyte count despite normal villi and crypts. Functional abnormality of the small intestine has not previously been reported in patients with this jejunal biopsy abnormality. Abnormalities of permeability were also found in patients with idiopathic diarrhoea, folate deficiency, postinfectious or traveller's diarrhoea, small bowel Crohn's disease, and atopic eczema. These results show that sugar permeability tests have more potential in clinical investigation than merely serving as screening tests before jejunal biopsy. There are groups of patients without morphological changes in the small bowel in whom intestinal permeability is abnormal.

Adolescent↗
PubMed1984

Prevalence of lactase deficiency in British adults.

The prevalence of lactase deficiency in British adults is unknown. Examination of the distribution of lactase activities in single and multiple biopsies of jejunum indicated that 0.8 U/g wet weight was a suitable cut-off point to separate lactase deficient patients from others. One hundred and fifty white British adults were selected, none of whom had significant intestinal disease and all of whom had normal histopathology of a jejunal biopsy and normal activities of other disaccharidases measured in the biopsy. The prevalence of lactase deficiency in this group was 4.7%. In contrast, 15 of 20 non-white adults were lactase deficient. Lactase deficiency was found in only three of 36 patients investigated because of diarrhoea after gastric surgery, and in 16 of 200 patients with irritable bowel syndrome (8%). As the prevalence of lactase deficiency is no higher in irritable bowel syndrome than in 'normal' individuals, lactase deficiency clearly is not a predisposing factor for irritable bowel syndrome in white British adults although the two conditions may occasionally coexist.

Adult↗
PubMed1984

Faecal weight, constituents, colonic motility, and lactose tolerance in the irritable bowel syndrome.

Lactose intolerance and faecal characteristics were compared in 16 patients with symptomatic irritable bowel syndrome and in age- and sex-matched controls. Faecal stool weight was increased in the irritable bowel syndrome patients, whereas faecal bile acids, fat, volatile fatty acids, and neutral sterols were not significantly different. No lactose intolerance was found in irritable bowel syndrome subjects. Measurements of colonic motility showed only modest activity for both basal and food-stimulated activity. There was a weak correlation between the concentration of total bile acids, deoxycholic acid, lithocholic acid and the motility index.

Adolescent↗
PubMed1983

The influence of peripheral vascular disease on methanogenesis in man.

Methane is produced by anaerobic bacterial metabolism in the colon and is excreted in the breath of only a proportion of healthy adults. Factors influencing methane excretion have still to be elucidated. The colonic vascular circulation may influence the intestinal environment facilitating growth of methanogens. The incidence of breath methane excretion has been investigated in patients with peripheral vascular disease and a control patient group. The proportions of subjects excreting methane in the control hospital group (43%) and in patients with predominantly femoro-popliteal disease (30%) were significantly less than in patients with predominantly aorto-iliac disease (83%) (P less than 0.005 and P less than 0.001, respectively). The presence of abdominal aortic arterial disease appears to be associated with a high incidence of methane excretion.

Aged↗