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Biomedical subjects

J Yudkin

Publications and source records attributed to J Yudkin.

At least 73 records · Page 4Linked to original sources
PubMed1976

The haemodynamic effects of metabolic acidosis in the rat.

1. The effect of metabolic acidosis of 4-6 h duration on cardiac output, blood pressure, heart rate, and hepatic and renal blood flow has been studied in the rat. 2. In anaesthetized rats, blood pressure and heart rate fell linearly with blood pH in both sham-operated and nephrectomized rats. There was no significant difference between the two groups in the effect of acidosis on either variable. 3. Cardiac output showed a significant fall with increasing acidosis in the conscious rat. 4. Estimated hepatic blood flow in conscious rats showed a significant positive correlation with blood pH in both sham-operated and nephrectomized animals. There was no significant difference in estimated hepatic blood flow between the two groups of animals at any blood pH. 5. In conscious rats, increasing acidosis caused a progressive decrease in estimated renal blood flow. 6. It is concluded that the increase in the previously described apparent renal contribution to lactate removal in the acidotic rat cannot be explained by any circulatory effect mediated by the kidney. The possible relevance of the findings to lactate homeostasis is discussed.

Acidosis↗
PubMed1976

The effect of acidosis on lactate removal by the perfused rat kidney.

1. The isolated perfused kidneys of fed rats in normal acid-base status showed a constant rate of lactate removal from the perfusate between 5 and 90 min of perfusion at a perfusate pH of 7-4-7-5. 2. Lactate removal by kidneys of rats in normal acid-base status was stimulated within 30 min by a reduction in perfusate pH to 7-1-7-2, but depressed when perfusate pH was reduced further. 3. Kidneys taken from rats previously made acidotic and perfused with media of various pH values showed a progressive fall in the rate of lactate removal during the perfusion. 4. Glucose output by the kidneys of rats in normal acid-base status perfused with lactate as substrate was not affected by an alteration in perfusate pH. The kidneys of acidotic rats generally showed an increased rate of glucose output compared with those of control rats.

Acid-Base Imbalance↗
PubMed1975

Special diets in hospitals: discrepancy between what is prescribed and what is eaten.

An assessment has been made in four hospitals of the food eaten by 40 patients on special diets restricted in energy, carbohydrate, fat, protein, or sodium. The diets eaten by most patients were significantly different from those prescribed, partly because of patients' unrestricted access to food they possessed or could buy in the ward, but mainly because of the extra or alternative foods provided by ward staff. Not only may the patients, progress be prevented or hindered by excessive consumption but also the lack of progress may be interpreted as indicating that the dietary treatment has failed rather than that it has not been followed.

Attitude of Health Personnel↗
PubMed1975

The contribution of the kidney to the removal of a lactic acid load under normal and acidotic conditions in the conscious rat.

1. The rate of removal from the circulation of an intravenous lactic acid load has been studied in conscious rats, previously subjected either to bilateral nephrectomy or to a sham operation. 2. In rats with normal blood pH, the apparent contribution of the kidneys to removal of the lactic acid load is 30%; less than 12% of the renal contribution is attributable to urinary excretion. 3. In bilaterally nephrectomized rats made acidotic by administration of ammonium chloride, the rate of removal of a half-neutralized lacrtic acid load is progressively decreased with increasing severity of acidosis. No such effect is seen in sham-operated animals. 4. An increase in the ability of the kidney to remove lactate during acidosis compensates for approximately half of the simultaneous fall in the capacity of the remainder of the body for lactate assimilation. 5. Basal blood lactate concentrations fall in the presence of metabolic acidosis.

Acidosis↗
PubMed1975

Some effects of different dietary carbohydrates on pregnancy and lactation in rats.

Female rats were fed from weaning on diets with sucrose, starch, glucose or fructose as the carbohydrate source. Animals were killed at various stages throughout pregnancy and early lactation. Maternal plasma triglycerides (TG), cholesterol, free fatty acids, glucose, insulin and corticosteroids were measured. Lipogenic activity was assayed in the livers, adipose tissue and mammary tissue, and the results compared with those from non-pregnant rats. Insulin, corticosteroids and hepatic lipogenesis were also assayed in the embryos and in newborn pups. Dietary sucrose and fructose produced a significantly higher concentration of plasma TG in the non-pregnant, pregnant and lactating rats than did starch and glucose. All the diets led to an increase in TG concentration at the 20th day of pregnancy, which returned to the original concentration 2 days post-partum. The hypertriglyceridaemia of late pregnancy was accentuated by the feeding of sucrose and fructose. Maternal concentrations of plasma glucose were significantly reduced towards the end of pregnancy in all dietary groups. The replacement of starch by sucrose, or of glucose by fructose, enhanced hepatic lipogenesis. Fructose but not sucrose depressed fat synthesis in the adipose tissue. Hepatic fatty acid synthetase activity was increased in late pregnancy on all diets except that with starch. Late pregnancy intensified hepatic lipogenesis in rats fed sucrose or fructose. The results are discussed in relation to the metabolic changes during pregnancy and to sucrose feeding.

Adipose Tissue↗
PubMed1975

A comparison of dietary starch and dietary sucrose in the pig.

Seven litter-mate pairs of male crossbred pigs were fed diets in which 50% of the dry weight was either corn starch or sucrose for 1 year. Unlike reports of two similar experiments published since our work was carried out, no lesions of the cardiovascular system were found in any of the animals at the end of the experiment. The sucrose-fed animals differed from those fed starch in the following respects: growth was faster during the first 9 weeks of the experiment, but became significantly slower during the remaining 43 weeks, with a less efficient food conversion. The pancreas was about 30% smaller but with no difference in gross or histological appearance. In the plasma there was a transient increase in concentration of insulin, a decrease in albumin, and a decrease in activities of glutamate-oxalacetate transaminase and lactate dehydrogenase. No significant changes in plasma cholesterol and triglyceride, phospholipid or glucose were observed.

Animals↗