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Biomedical subjects

D J Naismith

Publications and source records attributed to D J Naismith.

At least 19 recordsLinked to original sources
PubMed1994

Modulating influence of barley on the altered metabolism of glucose and of basement membranes in the diabetic rat.

A study was conducted to explore the effects of different sources of dietary carbohydrate on the altered metabolism of basement membrane proteins (type IV collagen and laminin) that occurs in the streptozotocin-diabetic rat. The substitution of barley for sucrose reduced the elevated plasma concentration of 7-S collagen and of laminin P2, peptide fragments that retain antigenicity of the parent proteins. Similar effects were noted in the liver and kidney content of these peptides. It is suggested that the beneficial property of barley is due to its high content of chromium, as has been demonstrated in the study of glucose metabolism.

Animals↗
PubMed1991

Therapeutic value of barley in the management of diabetes.

The alleged beneficial properties of barley in the treatment of diabetes were investigated. Rates of growth, water and food (digestible energy) intakes, and blood glucose concentrations were measured before and after the induction of diabetes in rats fed diets containing either barley or wheat. No differences were found in healthy animals, but in the diabetic state the blood glucose concentration, water consumption and weight loss was significantly lower in the rats fed barley. It is suggested that a factor other than the fibre content of the cereals may be responsible for the difference in response.

Animals↗
PubMed1991

Role of chromium in barley in modulating the symptoms of diabetes.

In adult diabetic rats, a diet containing barley had a modulating effect on the symptoms of diabetes (blood glucose concentration and water consumption) when compared with a starch or sucrose-based diet. It was postulated that the beneficial effect of barley might be explained by its very high content of chromium (5.69 micrograms/g). Supplementation of the sucrose-based diet with an amount of trivalent inorganic chromium calculated to be equivalent to the available chromium in the barley-based diet abolished the differences in response to the diabetic state.

Animals↗
PubMed1990

Nutrient intakes, vitamin-mineral supplementation, and intelligence in British schoolchildren.

Children (227), aged 7-12 years, weighed and recorded all food and drink consumed for seven consecutive days. Each child completed tests of verbal and non-verbal intelligence, and was then randomly allocated to one of two groups after matching for age, sex, IQ and height. In a double-blind trial lasting for 28 d, one group received a vitamin-mineral supplement daily and the other group a placebo. On re-testing, there were no significant differences in performance between the two groups. Furthermore, there was no consistent correlations between test scores and micronutrient intakes based on the weighed records. Thus, we found no evidence that learning ability in a cross-section of British schoolchildren was limited by the quality of their diets.

Body Height↗
PubMed1988

Effect of prolactin on amino acid catabolism in the female rat.

Rats treated with prolactin showed a rise in food consumption and an increased deposition of both lean tissue and fat. Rats pair-fed with untreated controls showed an increase in lean tissue, and a reduction in the activities of two key enzymes that control amino acid oxidation and urea synthesis in the liver. This adjustment in protein metabolism may regulate the amino acid supply in relation to the needs for milk protein synthesis during lactation.

Adipose Tissue↗
PubMed1987

Adaptations in protein metabolism during lactation in the rat.

1. The activities of two hepatic enzymes that participate in the regulation of amino acid oxidation and urea synthesis were measured in lactating rats (day 15 of lactation) and virgin controls. The enzymes were alanine aminotransferase (EC 2.6.1.2) and argininosuccinate synthase (EC 6.3.4.5). Carcasses of the dams were also analysed. 2. Changes in the activities of both enzymes in dams fed ad lib. on a diet containing an excess of protein indicated that amino acid oxidation was depressed. In dams restricted in protein to the level of intake of their controls but allowed to satisfy their needs for energy, enzyme activities were significantly reduced. In these animals lean tissue catabolism supplemented the dietary protein supply. 3. This adjustment in protein metabolism which effectively spares protein for milk-protein synthesis could be explained either by a reduction in the availability of substrate in the liver, or by the intervention of an anabolic hormone secreted in lactation.

Adaptation, Physiological↗
PubMed1987

Metabolism of taurine during reproduction in women.

The pattern of excretion of taurine was measured in four omnivore and four vegan/vegetarian women during pregnancy and lactation, and was compared with the changes in urinary excretion of other amino acids, including the precursors of endogenous taurine, observed in ten pregnant omnivores. The loss of taurine in breast milk was also determined in fourteen omnivore and fourteen vegan mothers. In contrast to the rise in excretion of all amino acids during pregnancy, including methionine and cysteine, taurine excretion fell dramatically from week 9 of pregnancy in all subjects, and, in the vegan/vegetarian subjects, fell still further during lactation. Although the concentration of taurine in breast milk was lower in vegan subjects, the mean value fell within the range found in omnivore subjects. Our findings indicate that the suppression of urinary taurine excretion, both during pregnancy and lactation, is a physiological response to reproduction that satisfies the needs of the fetus and the suckling infant for this amino acid. The data also suggest that taurine is stored in the maternal tissues in early pregnancy for later transfer to the fetus.

Adult↗
PubMed1984

The influence of a maternal diet rich in linoleic acid on brain and retinal docosahexaenoic acid in the rat.

Female rats were given throughout pregnancy and lactation a semi-synthetic diet, in which the fat was provided entirely by a soft margarine rich in linoleic acid (18:2 omega 6) or by mixture of butter and lard, and the influence on the fatty acid composition of fetal and pup brain and retinal phosphoglycerides was studied. The percentage of docosahexaenoic acid (22:6 omega 3) was much lower but that of docosapentaenoic acid (22:5 omega 6) was correspondingly higher in the brains of the day-22 fetuses and the 21-d-old pups from the margarine group compared with those from the group given the animal fats. Similar changes were noted in the synaptosomal and retinal phosphoglycerides, being most marked in the ethanolamine phosphoglycerides. The remaining pups from two groups were weaned on day 21 post partum on to the same stock diet that contained preformed 22:6 omega 3. After 9 weeks of this diet, the differences between the two groups in the fatty acid composition of the brain phosphoglycerides were barely discernible. The percentage of 22:5 omega 6 had decreased and had been replaced by 22:6 omega 3. It is concluded that the consequences of consuming a diet rich in linoleic acid and almost devoid of 22:6 omega 3 on brain fatty acid composition deserve consideration in man.

Animals↗
PubMed1982

The effect of early postnatal undernutrition on the growth and development of the rat brain.

1. Rat pups were undernourished during the period of the brain growth-spurt by feeding their mothers a low-protein diet from the third day post partum. 2. The pups were killed on days 5, 6, 9, 12, 16, 20 and 24 post partum, and their brains were analysed for protein, DNA, glycosides and glycoproteins. The activities of four enzymes involved in neurotransmission, and in the synthesis of glycolipids and myelin were also measured. Results of the analyses were compared with those obtained for pups that were suckled by well-nourished dams. 3. The brains of the undernourished pups contained substantially less protein and DNA; gangliosides and glycoproteins were also reduced. 4. All four enzymes showed lower peak activities in the nutritionally deprived animals, and the attainment of peak activity was retarded by several days. 5. These results suggest that undernutrition imposed during the brain growth-spurt leads to a deficit in the glial cell population and thus in the capacity to form myelin, and reduced development of cellular processes.

Aging↗
PubMed1982

The utilization of protein and energy during lactation in the rat, with particular regard to the use of fat accumulated in pregnancy.

1. The deposition of fat during pregnancy and its subsequent mobilization during lactation was studied in the rat. The utilization of protein during lactation was also investigated. 2. Fat accumulation was rapid and continuous from early pregnancy. Approximately one-third was deposited subcutaneously, the remainder being stored in central depots. 3. The volume of milk produced during lactation was varied by offering protein at two concentrations from day 2 post partum. Optimum lactation was achieved with a high-protein diet. The dams lost no body protein, but 60% of the total body fat was mobilized, despite a marked increase in food consumption. On a low-protein diet, food intake did not rise during lactation. Some body protein was catabolized and, again, 60% of the fat was mobilized although milk output, as judged by the gain in carcass energy of their pups, was reduced to approximately one-third of optimum. 4. Protein was used more efficiently by lactating rats, when compared with virgin controls. 5. We conclude that fat stored during pregnancy makes a major contribution to the energy costs of lactation, and that its mobilization is under hormonal rather than dietary control.

Adipose Tissue↗
PubMed1982

Carbohydrate conservation in the obese: a theory to explain the ease of weight gain.

Changes in the blood concentrations of non-chylomicron triglycerides, insulin, glucose, non-esterified fatty acids (NEFA) and alanine in response to a 4.18-MJ (1,000-kcal) meal were measured in 15 obese and 15 lean volunteers. No differences between the two groups either in quantity or in the pattern of change were detected in the triglycerides, glucose or alanine during the 7-hour period of study. Insulin levels were significantly higher in the obese subjects 1.25 h after the start of the meal, but at no other time. Plasma NEFA were initially depressed in both groups, but thereafter rose to much higher levels in the lean subjects. The results support the hypothesis that the obese conserve more of their ingested carbohydrate as liver glycogen for use between meals, and thereby avoid the high energy cost of fat synthesis.

Adult↗
PubMed1980

The metabolism of alpha-linolenic acid by the foetal rat.

The metabolism of [I-C14]linolenic acid (18:3 omega 3) by the foetal rat was studied in vivo and in vitro It is suggested that foetal brain has the capacity to convert linolenic to docosahexaenoic (22: 6 omega 3) acid to meet its requirements for docosalhexaenoic acid.

Animals↗
PubMed1980

Value of dietary protein for hyperplastic growth at restricted energy intakes.

The study describes three experiments of similar design relating dietary protein to growth over a period of 16 days in rats prematurely weaned at 19 days of age. In experiment 1, group 1 was fed ad libitum a 10% caseindiet. Group 2 was pair-fed an isoenergetic 40% casein diet. Groups 3 and 4 received 3 g of the 10% casein and 40% casein diets, respectively. The experiment demonstrated that protein may be used to sustain growth when energy intake is restricted. In experiment 2, all rats were given 3 g of diet per day. Group 1 was given the 10% casein diet, group 2 the 40% casein diet, group 3 a diet with 10% casein plus 30% of a mixture of dispensable amino acids and group 4 the 10% casein diet plus an energy supplement. Results showed that amino nitrogen seems to be a requisite for organ protein synthesis. In experiment 3, group 1 ate the 10% casein diet, group 2 the amino acid-supplemented diet and group 3 the latter minus glycine. Group 3 showed increased liver and kidney growth. The inclusion of glycine in group 2 caused a further increment in organ protein content.

Animals↗