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Biomedical subjects

A Wise

Publications and source records attributed to A Wise.

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

Dietary influence on caecal microbial nitroreduction of a drug: metronidazole.

Six diets were fed to weanling rats and the in vitro caecal microbial nitroreduction rates of metronidazole were determined. The sensitivity of this metabolic pathway to diet was demonstrated by the observed 20-fold range in reaction rate constant. Methods were devised to investigate the mechanism of this dietary effect. It was concluded that indigestible dietary components affected primarily both the weight of caecal contents and the metabolic activities of the microorganisms per unit weight of caecal contents. It appeared that the actual reaction rate in the caecum might be 35% higher than that determined by the standard assay procedure that involves sample dilution. However, the different soluble materials in the caeca derived from rats fed different diets had no significant secondary regulatory effects on the rate constant.

Anaerobiosis↗
PubMed1981

Binding of cadmium and lead to the calcium-phytate complex in vitro.

Low concentrations of cadmium (Cd) and lead (Pb) are unable to precipitate phytate, but in the presence of calcium (Ca) a precipitate is formed that binds both toxic metals. Almost complete binding of both metals has been observed at calcium-phytate ratios occurring in laboratory animal stock diets. Such binding may help to explain why the metals are less available to rats fed stock diets than to those fed phytate-free semisynthetic ones.

Animal Feed↗
PubMed1981

Variation of minerals and trace elements in laboratory animal diets.

29 laboratory animal diets from 5 manufactures for rats, mice, rabbits, guineapigs, primates and dogs were analysed for calcium, total phosphorus, phytate phosphorus, magnesium, sodium, potassium, iron, zinc and copper. Variations between diets for the same species were found to be much larger than differences between means for different species. The analyses were compared with data in the manufactures' catalogues. The best controlled element was potassium. Most deviations of other elements were distributed in a skewed fashion and quite serious differences between analytical and catalogue data were found. In general, deviations from the catalogue were less than variations between diets. It is recommended that catalogues should give ranges of composition rather than means.

Animal Feed↗
PubMed1980

The relative importance of genetics and diet in determining adipocyte number and size in the periovarian fat pad of the rat.

Seven types of rat were fed either stock diet, wheat diet, or a high-fat diet for 98 days. Little difference was found for any parameter between rats fed the wheat and stock diets, but compared to rats fed the stock diet, body weight was 9 per cent higher in the rats fed the high-fat diet, and body-fat proportion was 31 per cent higher. The adipocytes contained 32 per cent more fat and were present in 42 per cent greater number. The extent of dietary-induced difference depended on the strain, but in any case was a much less important determinant of adipocyte number than the genetic differences already existing in the rats. When the extreme groups of Zucker-obese and wild rats were excluded, the diet assumed greater importance in determining adipocyte size and number.

Adipose Tissue↗
PubMed1978

Urinary excretion of aflatoxin M1 after administration of aflatoxin B1 in sucrose- or starch-rich diets.

1. Male Sprague--Dawley rats were given 630 g/kg sucrose or starch with 2 mg/kg aflatoxin b1 for periods of 75, 145 and 200 d, and the 24 h urinary excretion of aflatoxin M1 was measured. 2. Less aflatoxin M1 was excreted by the rats fed on the sucrose-rich diet compared to those fed on the starch-rich diet. This difference was especially marked when expressed per g metabolizing tissue. 3. It is concluded that sucrose probably decreases the activity of aflatoxin B1 metabolism in a similar way to its previously found effect on the drug-metabolizing enzyme.

Aflatoxins↗
PubMed1977

The effect of a low protein diet on the adipocytes of rat perigenital fat.

Weanling rats were fed a low protein diet for 6 weeks and their weights were 50% less than controls. There were significantly fewer adipocytes per microgram adipose tissue, but estimates of the number of adipocytes per rat indicated that the diet had much less effect on adipocyte number than on b. wt.

Adipose Tissue↗
PubMed1977

Use of high dose corticosteroids in patients with inoperable brain tumours.

Eleven patients with inoperable brain tumours were treated with high doses of corticosteroids (methylprednisolone 200-2000 mg/day) for up to 151 days (mean 55 days). Neurological improvement occurred in eight patients on high doses after deterioration on concentional doses (methylprednisolone 80-120 mg/day). In two patients steroids could be completely discontinued for several months. Serious adverse effects included sepsis in three patients and myopathy in tow. All three patients with sepsis also received chemotherapy. There were no deaths that could be attributed to steroids. The most likely effect of high dosage steroids is reduction of cerebral oedema. It is conceivable that in some instances high dose steroids may also result in tumour inhibition or oncolysis or both.

Adult↗
PubMed1976

Species and hybrid differences in frequencies of play and agonistic actions in canids.

Developmental changes in the frequency of occurrence of some 23 action patterns were studied in pairs of coyotes, wolves, dogs and their hybrids. Over 4,300 entries were recorded from days 24--42 (85.5 h observations in toto). All subjects showed a decrease in contactual behaviors from 24--30 days, and a subsequent increase in play fighting and chasing. In all species, with the exception of the coyotes, the bite was inhibited and play behavior was recorded from 24 days onwards, but only after the 30th day in the coyotes. Species differences in occurrence and frequency of certain action patterns were evident in the wolves, coyotes and dogs, and these differences were also reflected in their hybrids.

Age Factors↗
PubMed1976

The energetics of "catch up" growth.

Animals, prevented from growing and then refed a good diet ad libitum, growth faster than normal and this is called "catch up" growth. This experiment was designed to show whether this is achieved by eating more food or by a greater efficiency of energy utilisation. Groups of rats (either 3 or 5 weeks old) were maintained at constant weight for a month, either by reducing the quantity of a good diet or by reducing the proportion of dietary protein. Food intake and carcass gain were measured for a period of 6 days "catch up" growth and compared with the control growth of rats with the same starting weight. It is concluded that "catch up" growth is associated with increased energy intake and increased efficiency when expressed as food conversion and gross energetic efficiency. There are, however, specific age differences in the metabolism of "catch up" growth which may be due to variation in either the maintenance requirement or the efficiency of protein and fat synthesis. This experiment emphasizes the differences between the various available expressions of energy utilisation.

Age Factors↗