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Biomedical subjects

N I McNeil

Publications and source records attributed to N I McNeil.

At least 19 recordsLinked to original sources
PubMed1990

The effect of lactulose, pectin, arabinogalactan and cellulose on the production of organic acids and metabolism of ammonia by intestinal bacteria in a faecal incubation system.

An in vitro faecal incubation system was used to study the metabolism of complex carbohydrates by intestinal bacteria. Homogenates of human faeces were incubated anaerobically with added lactulose, pectin, the hemicellulose arabinogalactan, and cellulose, both before and after subjects had been pre-fed each carbohydrate. Fermentation of added substrate was assessed by the production of short-chain fatty acids (SCFA) and suppression of net ammonia generation over 48 h of incubation. Control faecal homogenates to which carbohydrate was not added yielded an average increment of SCFA of 43 mmol/l, equivalent to 172 mmol/kg in the original stool. The addition of lactulose, pectin and arabinogalactan each increased the yield of SCFA by a similar amount, averaging 6.5 mmol/g carbohydrate or 1.05 mol/mol hexose equivalent; organic acid yield was not increased by pre-feeding these substances for up to 2 weeks. Acetate was the major SCFA in all samples at all times and, after pre-feeding with extra carbohydrate, butyrate concentrations exceeded propionate in all samples. Faecal homogenates incubated with cellulose showed no greater SCFA production than controls over the first 48 h, but there was a slight increase when samples from two subjects pre-fed cellulose were incubated for 14 d. Net ammonia generation was markedly suppressed by addition of lactulose to faecal incubates with an initial period of net bacterial uptake of ammonia. Pectin and arabinogalactan also decreased ammonia generation, but the reductions were not significant unless subjects were pre-fed these materials; cellulose had no effect on ammonia generation.

Adult↗
PubMed1989

The interpretation of retrograde pancreatography in the elderly.

Endoscopic retrograde pancreatography is regarded as the most specific technique in the diagnosis of chronic pancreatitis. In the elderly the relevance of endoscopic retrograde pancreatography changes in establishing the diagnosis is disputed. The pancreatograms of 101 patients aged seventy-five years or more, who had endoscopic retrograde pancreatography for suspected biliary or pancreatic pathology, were reviewed. Only four patients subsequently proved to have unequivocal chronic pancreatitis. There was no significant difference in the size or contour of the main pancreatic duct, or in side branch changes between those patients presenting with common bile duct stones, incidental biliary pathology and pain of probable pancreatic origin. Three definite diagnostic criteria for the diagnosis of chronic pancreatitis emerged--duct obstruction with a stricture, gross irregularity of the main pancreatic duct and the presence of large cavities.

Aged↗
PubMed1987

Mucosal surface pH of the large intestine of the rat and of normal and inflamed large intestine in man.

The surface pH of rat distal colonic mucosa and human rectal mucosa was measured in vitro using first a small pH electrode with a flattened tip. In buffer with pH 7.56 the mean rat colonic surface pH was 6.72. Lowering the buffer pH in steps resulted in a small fall in surface pH, the values being buffer pH 7.06 surface pH 6.64, buffer pH 6.58 surface pH 6.61 and finally buffer pH 6.09 surface pH 6.39. Similar results were obtained with a buffer where butyrate, 30 mmol/l replaced chloride and when a CO2/bicarbonate buffer was used. During the time taken for the study transmural potential difference only changed by 1-2 mV. Serosal surface pH changed with buffer pH, suggesting that the maintained surface pH is a property of the mucosal surface only. The surface pH of human rectal mucosa was similar to that of rat distal colonic mucosa. As buffer pH fell from pH 7.51 to 5.96 mucosal surface pH only fell from pH 6.80 to 6.26. The values obtained in ulcerative proctitis did not differ from normal mucosa. Secondly pH microelectrodes were used to measure the juxta mucosal pH and the pH-microclimate thickness when luminal pH was controlled. The microclimate had a pH 6.63 adjacent to the mucosa with a thickness of 840 micron. The importance of mucus in maintaining the microclimate was shown by n-acetyl cysteine thinning and prostaglandin E2 thickening the layer. These results describe a surface microclimate in the large intestine of appreciable thickness and a constant juxta mucosal pH. Luminal pH changes produce only a small change in microclimate pH.

Adult↗
PubMed1986

The effect of luminal pH on large intestinal absorption in ulcerative proctocolitis.

The sensitivity of large intestinal absorption to pH and the absorption of short-chain fatty acids were measured in ulcerative proctocolitis by a dialysis bag method. Lowering luminal pH from 7 to 5.5 significantly reduced absorption of salt and water in proctocolitis, but not in normal controls. Short-chain fatty acid absorption was not affected by inflammation or change in pH when patients with ulcerative proctocolitis were compared with controls.

Adult↗
PubMed1986

Meningitis caused by Streptococcus suis type II.

A 49 year old head porter developed meningitis shown to be caused by Streptococcus suis type II. The rare human infections with the organism, a pathogen of pigs, usually occur in those employed handling pig meat and are associated with auditory or vestibular dysfunction.

Animals↗
PubMed1984

Domestic metallic mercury poisoning.

In a family exposed to metallic mercury vapour two patients had acrodynia, one had the nephrotic syndrome, and one person remained well. Recognition of the variable manifestations of the disease and prevention of further exposure were the most important aspects of management. Recovery appeared to be complete as blood mercury levels fell to normal. Urinary mercury levels were too variable to be reliable as indications of progress.

Accidents, Home↗
PubMed1984

The contribution of the large intestine to energy supplies in man.

Herbivores obtain a considerable proportion of energy requirements from carbohydrate by the chain of anaerobic carbohydrate fermentation producing short-chain fatty acids that are absorbed then metabolized. The evidence for this sequence occurring in the large intestine of man is reviewed and estimated to produce 5 to 10% of human energy requirements. Further small amounts of energy may come from large intestinal absorption of fat and the bacterial breakdown products of protein.

Animals↗
PubMed1984

Nutrition after ileostomy.

The nutritional consequences of life with an ileostomy have been reviewed. Ileostomists tend to eat earlier in the day and to avoid fruit and vegetables when compared to people without an ileostomy. They are generally well nourished but may be prone to salt and water depletion because of the continual losses in the ileal effluent. The reservoir and absorptive capacities of the intact colon are demonstrated by these studies conducted on people with an ileostomy.

Feeding Behavior↗
PubMed1983

Analgesic ingestion and other factors preceding relapse in ulcerative colitis.

To investigate factors which predispose to relapse in patients with ulcerative colitis, we conducted a survey to compare the events occurring in the four weeks preceding the clinic attendance of 62 outpatients in remission with those taking place in the same period before the onset of relapse in 21 patients attending with active disease. The only event which occurred significantly more often in patients who subsequently relapsed was ingestion of paracetamol and other inhibitors of prostaglandin synthesis (76% (16/21) relapse vs 39% (24/62) remission, p less than 0 . 01). Recent upper respiratory tract infection (38% vs 26%) was not significantly more common in patients in relapse than in remission, and emotional stress, atopic events, antibiotic treatment, dietary indiscretions, foreign travel, and gastroenteritis were relatively rare in both groups. The surprisingly high prevalence of analgesic ingestion before relapse itself requires confirmation but does lend indirect support to the theory that colonic mucosal prostaglandin deficiency induces relapse in some patients with ulcerative colitis.

Acetaminophen↗
PubMed1982

Diet and health of people with an ileostomy. 1. Dietary assessment.

1. People with an ileostomy experience digestive problems with some foods. Why those foods are avoided is not known nor is it certain whether this interferes with the nutritional adequacy of their diet. 2. A detailed dietary assessment has therefore been made of thirty-seven subjects with ileostomies and a similar number of age- and sex-matched healthy controls. All food and drink eaten over 1 week was weighed and recorded. In addition. A larger group of seventy-nine ileostomy subjects and seventy matched controls answered a questionnaire designed to identify foods which upset them and which they avoided. 3. Total nutrient and energy intakes were similar in the two groups but the subjects with an ileostomy ate less dietary fibre (g/d; mean + SD: ileostomy subjects 18.0 +/- 5.9, controls 20.9 +/- 5.5; P less than 0.05) mainly due to lower fruit and vegetable intakes. Iron and vitamins A and C intakes were also less. 4. A majority of ileostomy subjects had a pattern of food intake different from the controls, taking more of their energy in the morning and less at night. A variety of food items upset more than half of them including nuts, pips, seeds, skins, onions, beetroot, lettuce, raw cabbage and carrot, peas, sweetcorn, mushrooms and dried fruit. 5. On the basis of the results it is possible to formulate general dietary advice for people with an ileostomy.

Adult↗
PubMed1981

The diet of individuals: a study of a randomly-chosen cross section of British adults in a Cambridgeshire village.

1. The dietary intakes of sixty-three adults, randomly-selected from the electoral role of a large village near Cambridge, have been measured using the weighed-intake technique for 7 d. 2. Mean (+/- SD) daily intakes (g) for men and women respectively were: energy (MJ) 10.0 +/0 2.4, 8.2 +/- 2.1; fat 104 +/- 27, 90 +/- 27; protein 77 +/- 20, 67 +/- 16; carbohydrate 285 +/- 81, 229 +/- 74; sucrose 91 +/- 47, 57 +/- 33. 3. When interviewed at the end of the study 40% of subjects said they were watching their weight. 4. Women ate less food over all than men, and proportionately less potato and bread, and used only one-third as much sugar in drinks, probably in an attempt to control their weight. Men took considerably more alcohol than the women. In the age-group 20-39 years alcohol provided 9% (1.0 MJ/d) of the total energy intake in the men. 5. Wide variation in the intake of nutrients was observed amongst the individuals. For vitamin C and fibre intake this was partly partly explained by seasonal variation but for most nutrients total energy intake and food choice were the main determinants. The range of intakes of nutrients such as fat was similar in these individuals to that seen amongst countries internationally. It is suggested that if differences in nutrient intake amongst the various populations of the world can be associated with disease risk, then the same interpretation should be possible in individuals.

Adult↗
PubMed1979

Intakes and sources of dietary fiber in the British population.

Intakes of dietary fiber and its different components have been measured in a random sample of the population in Cambridgeshire, England and compared with data from the British National Food Survey. Sixty-three men and women ages 20 to 80 were included in the sample. Total dietary fiber intake was 19.9 +/- 5.3 g/day compared with the calculated value of 19.7 g/day from the 1976 National Food Survey. There was a 4-fold range in fiber intake from 8 to 32 g/day; no significant trends with age or between men and women were detected. Vegetables supplied the majority of the fiber (41.3%); cereals 30.5%, and fruit and mixed sources 28.2%. Of the components of dietary fiber noncellulosic polysaccharide, cellulose, and lignin intakes were 13.8, 4.7, and 1.4 g/day, respectively. In the noncellulosic fraction, hexoses contributed 7.4 g, pentoses and uronic acids 3.3 and 3.0 g. Vegetables and unrefined cereals were the main sources of pentose. These intakes are low in comparison with limited international data from developing countries and of a similar order to those known in dietary experiments to produce low stool weights, slow transit time, and concentrated feces. They could readily be increased by simple dietary changes.

Adult↗
PubMed1979

Rectal absorption of short chain fatty acids in the absence of chloride.

The absorption of short chain fatty acids by the human rectum in the absence of chloride has been studied using a dialysis bag technique. Absorption rates of sodium, water, and short chain fatty acids were unchanged on replacing chloride with sulphate. Final concentrations of bicarbonate were 35.4 +/- 3.4 mmol/l in the presence of chloride and 37.1 +/- 5.2 mmol/l in the absence of chloride. The rates of movement of bicarbonate into the dialysates were similar. If bicarbonate is secreted in exchange for chloride then it also appears to be secreted in exchange for absorbed short chain fatty acids.

Adult↗