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Biomedical subjects

L Bell

Publications and source records attributed to L Bell.

At least 109 records · Page 6Linked to original sources
PubMed1982

A scanning and transmission electron microscopical study of the morphogenesis of human colonic villi.

The morphogenetic events that occur in the development of villi in human foetal colon have been observed by light microscopy and scanning and transmission electron microscopy. At nine weeks, the colon is a simple tube composed of pseudostratified columnar epithelium and mesenchyme. By ten weeks, up to eight longitudinal ridges have formed by an elongation of individual epithelial cells. Even as the ridges are forming, the bases of some of the ridges become indented with mesenchyme thus forming longitudinal mucosal folds. By eleven and a half weeks, these have folded in a concertina fashion forming a longitudinal zig-zag pattern. From ten and a half weeks, small lumina develop within the epithelium near to its base. At this stage, they are not in continuity with the main lumen. Extension of these lumina to the main luminal surface and exfoliation of redundant cells result in division of the zig-zag folds into broad primary villi. Division of the primary villi occurs when cyst-like structures which develop within the pseudostratified columnar epithelium of the primary villi enlarge and extend to the lumen. Together with upgrowth of mesenchyme this results in small secondary villi with simple columnar epithelium.

Colon↗
PubMed1982

Revision of the Ontario phenylalanine equivalency system and development of a low protein equivalency system.

The Phenylalanine Content of Foods, an equivalency system used in the dietary treatment of phenylketonuria, was prepared in 1975. Recently this system was revised to include a total of 372 food items in various raw and processed states. Food lists are available in a simple version for parents listing the serving size per phenylalanine equivalent, and in a more comprehensive version for dietitians providing weights for the serving sizes as well as values for phenylalanine, protein, and energy per equivalent. Subsequently, the system was modified to form a low protein equivalency system for use in designing low protein diets for a number of other inherited metabolic disorders.

Diet Therapy↗
PubMed1982

Use and design of low protein diets for children with inborn metabolic disorders.

Low protein diets are used to treat infants and children with hyperammonemia due to urea cycle and other metabolic disorders as well as a number of amino and organic acidopathies. The incidence of these disorders is small and many are life-threatening. As a result, there is little in the literature on the dietary management of these patients. This paper draws on 10 years of clinical experience at the Hospital for Sick Children in Toronto, Ontario and presents a guide to the preparation of infant formulas providing levels of protein intake from 0.5 to 2.0 g per kg. Also described is a low protein equivalency system that is a useful guide for measuring both baby foods and table foods for affected children up to about six years of age. This dietary information is accompanied by a description of the disorders amenable to low protein diets, some of the adjunctive therapies employed and the nutritional concerns associated with severe restriction of protein.

Child↗
PubMed1981

Hyperornithinaemia and gyrate atrophy of the retina: improvement of vision during treatment with a low-arginine diet.

A 15-year-old patient with hyperornithinaemia (0.6--1.2 mmol/l) and gyrate atrophy of the retina was given a low-arginine diet to reduce plasma ornithine to a concentration (0.15--0.25 mmol/l) near the normal range. After five weeks of treatment, there was improvement in the visual function of one eye which had been severely impaired without improvement for 3 years. This improved visual function was maintained until compliance with the diet deteriorated at eight months, after which visual function regressed towards pretreatment status. Overrestriction of dietary arginine produced hyperammonaemia, indicating that arginine is an essential aminoacid in ornithine transaminase deficiency. These results suggest that reduction of plasma ornithine may reverse a metabolic neuroretinopathy in this disease, and offer hope that progression of the retinal atrophy can be arrested as well.

Adolescent↗
PubMed1980

Effect of cimetidine and sodium bicarbonate on pancreatic replacement therapy in cystic fibrosis.

Fifteen patients with cystic fibrosis and pancreatic insufficiency were studied during four randomised seven day treatment periods in which they received only pancreatic supplement (Pancrelipase, 27 capsules per day) or supplement plus cimetidine (20 mg/kg body weight/24 h) or sodium bicarbonate (15 g/m2/24 h) alone or in combination. Dietary intake was not fixed but was restricted to foods of known fat and nitrogen content from which daily intakes could be computed. Faecal fat and nitrogen were calculated as g/24 h and percentage of intake. Addition of either cimetidine or bicarbonate resulted in significant improvement in fat and nitrogen excretion, which was not greater with the combination of both drugs. Cimetidine and sodium bicarbonate in these doses are therefore sufficient to produce maximal improvement in digestive activity of pancreatic supplements. Fat excretion per gram of intake fell with cimetidine and bicarbonate from 12 times the normal level, to normal, in patients consuming less than 120 g fat daily. Above this intake the dose of pancreatic supplement appeared to be inadequate. Faecal nitrogen excretion increased with nitrogen intake in all four periods, but, in contrast with fat excretion, the response to cimetidine and bicarbonate was not affected by the level of intake. Dietary intake appears to be a significant factor in determining the faecal output of fat and nitrogen in patients with pancreatic insufficiency and should be considered when determining the optimum amount of pancreatic supplementation.

Adolescent↗
PubMed1980

Treatment of gyrate atrophy of the choroid and retina with low arginine diet.

In gyrate atrophy the blood ornithine is grossly elevated, due to deficiency of ornithine ketoacid transaminase, which converts ornithine towards glutamic acid. Two patients with gyrate atrophy have been treated with a low arginine diet and their blood ornithine levels have been reduced to near normal. At this level hyperammonemia may result from overtreatment, but this can be quickly cleared by a small dose of arginine. There has also been some improvement in vision, but no clearing of the gyrate areas. Future care with this regimen seems possible and improvements in handling of these patients are likely.

Adolescent↗
PubMed1979

Leptospirosis in meat inspectors: preliminary results of a serological survey.

A serological survey of leptospirosis among more than 1000 meat inspectors, from meat works throughout New Zealand, revealed a serological prevalence at a minimum serum dilution of 1:24, of 10.2 percent. Eighty-five percent of serological reactions were to serovars pomona and tarassovi. A highly significant correlation was demonstrated between the serological prevalence of these serovars and the inspection of pigs. Evidence is provided to substantiate the use of titres as low as 1:24 as an indication of previous leptospiral infection. Forty-two inspectors reported medical evidence of previous clinical infection with leptospirosis. Analysis of those who still exhibited a serological response and their individual case histories, indicated that detectable titres of leptospirosis can exist for up to 10 years.

Animals↗
PubMed1979

Histochemical demonstration of alkaline phosphatase in human large intestine, normal and diseased.

Alkaline phosphatase activity has been investigated by histochemical methods in normal and diseased human large intestine. The tissues were constantly maintained at 4 degrees C or below. Specimens were either frozen in liquid nitrogen, freeze-dried and embedded in glycol methacrylate for sectioning at 2 mu, or, fixed in ice-cold formol-calcium for frozen sectioning at 10 mu. The simultaneous coupling azo dye method using the substrates sodium alpha-naphthyl phosphate and Naphthol AS-BI phosphate, resulted in the demonstration of alkaline phosphatase activity in the surface epithelial cells, and the middle and upper crypts, of normal and transitional mucosa.

Alkaline Phosphatase↗
PubMed1979

Occurrence of crossed strand-exchange forms in yeast DNA during meiosis.

The crossed strand-exchange form (Holliday structure, half chiasma) has been predicted as an intermediate in the genetic recombination of eukaryotes. We report here the detection of this form in the yeast plasmid, 2-micron DNA, isolated during meiosis. Physical mapping has previously suggested that two forms of 2-micron DNA arise because of recombination between inverted repeat regions. After appropriate digestion with restriction endonuclease, a crossed strand-exchange form intermediate in this recombination would yield an X-shaped form resistant to loss by branch migration because of nonhomology in sequences flanking the region of homology. We first generated this X-shaped form artificially by reannealing melted restriction fragments of 2-micron DNA. This enabled us to develop a procedure for the physical separation of the X-shaped form by agarose gel electrophoresis. We then used this electrophoretic procedure to isolate a naturally occurring form of identical structure from the 2-micron DNA of meiotic cells. Electron microscopy demonstrated that the exchange junction had the expected configuration of strands and indicated that the junction occurred within the region of homology.

Crossing Over, Genetic↗
PubMed1976

Contraceptive knowledge and practice among undergraduates at a Canadian university.

A total of 509 undergraduate students aged 17 to 23 years, were tested to assess the adequacy of their knowledge of methods of birth control. A level of adequate knowledge was arbitrarily defined a priori as one standard deviation below the mean score of a random sample of second-year medical students, who were assumed to have more than adequate knowledge on the basis of prior courses in reproductive physiology and human sexuality. Of the undergraduate population sampled, 34 per cent were found to have inadequate knowledge. This population is in need of birth control information. Of nonvirgins in the sample, 20.2 per cent risk unwanted pregnancy, the majority (78.3 per cent) in spite of adequate knowledge. This suggests that lack of motivation, rather than purely lack of information, is an important factor contributing to the unwanted pregnancy rate of the college student population.

Adolescent↗
PubMed1976

Evaluation of an automated procedure for primary screening of hyperlipoproteinemias.

An automated procedure for the determination of beta-plus-pre-beta-lipoprotein cholesterol is described and evaluated for mass screening of hyperlipoproteinemias. It is shown that this method fulfills the requirements for an ideal method for primary screening: it can be used in non-fasting samples, is capable of detecting hyperlipoproteinemias characterized by both cholesterol and/or triglyceride abnormalities, is fast, accurate and extremely inexpensive. Evidence is shown that the method is extremely useful for primary screening and, when tested in a coronary screening detection program, gave only 4% false positive and 3.4% false negative results.

Autoanalysis↗
PubMed1975

Effect of exercise on lipid metabolism of rats fed high carbohydrate diets.

Two experiments were conducted to determine whether high carbohydrate diets or exercise would have a greater influence on certain parameters of lipid metabolism. Male Fischer rats were used in both experiments, separated into exercise and sedentary groups, and fed either a high sucrose (63%) or a high starch (63%) diet. There were no differences in body weight or food consumption between the two diets. Exercise resulted in a highly significant increase in food consumption in both experiments. Rats fed sucrose had a higher serum cholesterol value than rats fed starch. Diet did not influence serum triglycerides but the rats on excercise had significantly lower serum triglycerides than the sedentary rats. Liver weight was significantly larger in rats fed sucrose. Sucrose caused an increase in the activity of both glucose-6-phosphate dehydrogenase and malic enzyme activities in liver tissue, whereas exercise caused an increase in the activity of these enzymes in adipose tissue.

Adipose Tissue↗