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Biomedical subjects

R Hume

Publications and source records attributed to R Hume.

At least 145 records · Page 8Linked to original sources
PubMed1983

Endocrine and metabolic studies in unstable cor pulmonale.

Serum testosterone, follicle-stimulating hormone, luteinising hormone, and dihydro-epiandrosterone concentrations rose significantly in seven men studied during recovery from a severe exacerbation of chronic obstructive airways disease. Urinary 17-ketosteroids also rose significantly though serum androstenedione and prolactin concentrations did not. Our findings suggest that hypoxia in this condition suppresses the hypothalamus or pituitary or both and that such suppression is reversible. In view of previous reports of increase in total body potassium and intracellular water with recovery from cor pulmonale, we also carried out metabolic studies on our patients. Low body potassium concentrations in cor pulmonale fell further with recovery, in part reflecting a fall in lean body tissue. Intracellular water appeared to increase on recovery despite a fall in other lean body mass indices (the simplest and most reliable being skinfold thickness). We suspect this result to be spurious and due to problems with equilibration in isotope dilution. Alternatively it may reflect waterlogging of cells. A false figure for intracellular water could be responsible for an unexpectedly low estimated intracellular potassium concentration on recovery. Our results cast doubt on isotope dilution methods for measuring body water compartments in disease states likely to cause changes in cell permeability.

17-Ketosteroids↗
PubMed1983

Comparison of cerebral blood flow after venesection of bronchitic secondary polycythaemic and primary polycythaemic patients.

Cerebral blood flow was measured before and after lowering of haematocrit in four patients with primary polycythaemia and in nine with polycythaemia secondary to chronic obstructive airways disease. Cerebral blood flow values in each group were abnormally low to a similar degree at the start of the study and the degree of rise in cerebral blood flow per unit fall in haematocrit after venesection also was similar in each. Oxygen delivery fell despite increased cerebral blood flow and symptomatic benefit was infrequent. In male secondary polycythaemic patients rise in cerebral blood flow was not associated with any improvement in hypothalamo-pituitary-testicular function which we had previously noted to be suppressed in such hypoxic subjects. Our findings suggest viscosity changes rather than alteration in blood oxygen carriage to be responsible for cerebral blood flow improvement. It is concluded that therapeutic venesection in such patients should be applied with caution.

Adult↗
PubMed1982

Plasma alkaline phosphatase activity in rickets of prematurity.

Plasma alkaline phosphatase activity was measured in 349 infants aged between 5 and 10 days to establish a normal range for different gestational ages. Significant differences were observed between term and preterm infants, the highest values being associated with the shortest lengths of gestation. Plasma calcium, phosphate, and alkaline phosphatase activity were measured sequentially in 51 preterm infants less than 1500 g at birth. A significant correlation was found between raised plasma alkaline phosphatase activity and radiological changes of osteoporosis, metaphyseal change, and periosteal reaction. Plasma alkaline phosphatase appears to be of value in screening for and monitoring rickets of prematurity.

Alkaline Phosphatase↗
PubMed1982

Ascorbate status and fibrinogen concentrations after cerebrovascular accident.

Leucocyte ascorbate (LA) and serum ascorbate (SA) were measured in patients who had sustained an acute cerebrovascular accident. There was a significant fall in LA and Sa within 24 hours of the incident and this persisted for several weeks. The "stress" of the event resulted in a rise in serum cortisol concentration and depletion of both pituitary and adrenal glands of ascorbate when examined at post mortem. Serum fibrinogen concentrations also rose above normal. The role of ascorbate in pituitary and adrenal function and the relation of ascorbate to acute and chronic vascular disorders has still to be established.

Adrenal Glands↗
PubMed1982

The effect of megadose ascorbic acid ingestion on the absorption and retention of vitamin B12 in man.

Radiotracer B12 analogues, hydroxy- and cyano-cobalamin have been used to study the effects of megadose L-ascorbic acid (vitamin C) ingestion on vitamin B12 metabolism in man. By employing whole body counter techniques it has been shown that, while ascorbic acid can partially inactivate both the important dietary analogue, hydroxycobalamin, and the gastric secretion, intrinsic factor which is essential for B12 absorption, the rapid binding of the B12 analogue to intrinsic factor protects the hydroxycobalamin from attack. As a result, the absorption of hydroxcobalamin is unaffected by the simultaneous ingestion of 1 g ascorbic acid. The absorption of cyanocobalamin, the most stable analogue but not found in quantity in the diet, is slightly increased by ascorbic acid. Whole body retention studies on normal subjects ingesting 2 g ascorbic acid per day show no significant evidence of in vivo destruction of body B12 stores.

Anemia, Pernicious↗
PubMed1981

Hypothalamic-pituitary dysfunction in respiratory hypoxia.

Eight hypoxic male patients with stable chronic obstructive airways disease were submitted for combined anterior pituitary function testing. All subjects showed normal growth hormone and essentially normal cortisol responses to adequate hypoglycaemia, two subjects showed delayed responses of thyroid stimulating hormone to administered thyrotrophin releasing hormone and all had basal prolactin levels within normal limits. Basal levels of luteinising hormone were significantly lower than in the group of age-matched controls (p less than 0.02) but there was a normal increment after the injection of gonadotrophin releasing hormone. Basal levels of follicle stimulating hormone were significantly lower than in the controls (p less than 0.01), and there was also a reduced response from the pituitary after injection of gonadotrophin releasing hormone (p less than 0.01). Resting levels of the thyroid hormones thyroxine and tri-iodothyronine were normal while the expected subnormal testosterone level was observed (p less than 0.05). These results show that hypoxia can produce abnormalities of hypothalamic-pituitary function and that these are primarily located in the hypothalamic-pituitary-testicular axis.

Adult↗
PubMed1981

Distribution of glycocholate in blood from human fetuses and adults.

Glycocholate binding by plasma proteins and erythrocytes from fetal and adult blood has been studied, and the results have been used to derive a compartmental model of the distribution of glycocholate in blood. This model assumes that glycocholate is distributed between the aqueous phase, albumin binding sites, binding sites on other plasma proteins, and erythrocytes. Whereas glycocholate binding by albumin was saturable [fetal blood: dissociation constant (0.5 mM), concentration of binding sites (11.3 mumoles/g protein); adult blood: dissociation constant (0.42 mM), concentration of binding sites (20.1 mumoles/g protein)], binding by other plasma proteins was not. The association of glycocholate with erythrocytes appeared to be based on partitioning rather than binding of the bile salt to specific sites. The value of the partition coefficient was 6.0. The compartmental model indicates that, in fetal blood, 46% of the glycocholate is in free solution, and 37% is bound to albumin. In blood from adults, the corresponding values are 31% in free solution and 59% bound to albumin.

Adult↗
PubMed1980

Oral absorption of lead and iron.

Oral lead and iron absorptions have been measured by the use of radioactive tracer techniques in ten subjects, five of whom had low iron stores as shown by low serum ferritin. The absorption of both elements was abnormally high in these five and also in one subject with normal serum ferritin. The other 4 subjects, who were iron-replete, had absorption values in the normal range. The statistically significant positive correlation between oral lead and iron absorptions suggests that the sizeable proportion of the population "overabsorbing" iron may absorb two to three times more lead than the generally accepted value of 10% of dietary input.

Adult↗
PubMed1980

A comparison of erythrocyte glutathione S-transferase activity from human foetuses and adults.

Glutathione S-transferase activity was measured in partially purified haemolysates of erythrocytes from human foetuses and adults. Enzyme activity was present in erythrocytes obtained between 12 and 40 weeks of gestation. The catalytic properties of the enzyme from foetal cells were similar to those of the enzyme from adult erythrocytes, indicating that probably only one form of the erythrocytes enzyme exists throughout foetal and adult life.

Chromatography, Gel↗
PubMed1979

Diet, absorption, and hormone studies in relation to body weight in obstructive airways disease.

Sixteen male patients with stable chronic obstructive airways disease were separated into two groups of eight according to arterial carbon dioxide tensions. Hypercapnia was associated with lower arterial oxygen tensions, higher red cell volume, and increased weight, while normocapnic subjects were decidedly thin. The considerable difference in body weight between the two groups could not be explained by variation in caloric intake, and malabsorption was excluded as a cause of weight loss in the underweight subjects. Serum tri-iodothyronine, thyroxine, cortisol, and oestradiol concentrations were similar and normal in each group, but both groups had significantly low testosterone values as compared with controls, values in the hypercapnic being appreciably lower than in the normocapnic group. The adrenal androgen dehydroepiandrosterone was significantly high in the normocapnic group and low in the hypercapnic group compared with controls. Serum pituitary luteinising and follicle stimulating hormones were normal, but three hypercapnic individuals had high serum prolactin values. Early morning urinary aldosterone values were significantly higher in the hypercapnic than in the normocapnic group. Such hormone comparisons have not previously been made in subjects with chronic obstructive airways disease grouped according to arterial blood gas values, and it is concluded that major alterations in adrenal and testicular function may occur, possibly due to pituitary suppression from hypoxia. Such hormonal changes might in part account for the contrasting alterations in body habitus found in this condition.

Aged↗
PubMed1978

Reassessment of changes in leucocyte and serum ascorbic acid after acute myocardial infarction.

After an acute myocardial infarction, there is an apparent acute fall in leucocyte ascorbic acid associated with an acute rise in white blood cells and serum cortisol. The apparent fall in leucocyte ascorbic acid is the result of the granulocytosis which occurs after the infarction. Estimations of ascorbic acid disclose that the granulocyte contains approximately half the ascorbic acid of the lymphocyte. When the granulocytosis subsides, the new population of white blood cells is depleted of ascorbic acid for at least 56 days, reflecting tissue desaturation which can be corrected by ascorbic acid supplements. Tissue desaturation is also reflected in subnormal serum ascorbic acid levels which persist also unless ascorbic acid supplements are given. Observations on normal subjects given infusions of tetracosactrin (Synacthen) show that adrenal stimulation can produce a similar rise in white blood cells and an apparent fall in leucocyte ascorbic acid concentration with the exception that the serum ascorbic acid remains unaltered. Therefore, while adrenal stimulation can mimic 'stress' with regard to the changes in the white blood cells, tissue depletion of ascorbic acid as reflected in the white blood cells and serum after a myocardial infarction requires a focus of damaged tissue.

Adrenal Glands↗
PubMed1978

Potassium studies in chronic obstructive airways disease.

Seventeen male patients with chronic obstructive airways disease in remission were separated into two groups according to arterial carbon dioxide tensions. Hypercapnia was associated significantly with hypoxia and increased red cell volume whereas normocapnia was not. Normocapnic patients were significantly lighter than those with hypercapnia. Total body potassium (TBK) measured by the whole body monitor was significantly low in two of the patients studied (P less than 0.005). The mean value for TBK for the normocapnic group as a whole was significantly low (P less than 0.005), but the mean value for the hypercapnic group was not. Serum potassium and erythrocyte potassium concentrations were normal even when TBK was low, and diuretics had no apparent influence on these potassium values. Of four patients (two in the series and two others) who had TBK measured after a recent episode of cor pulmonale, three had significantly low values. The only previous studies using a whole body monitor to measure TBK in chronic obstructive airways disease found no such low values, though other workers estimating exchangeable potassium by isotope dilution techniques had found evidence of gross potassium depletion. It is concluded that low TBK does indeed occur in patients with chronic obstructive airways disease and that gross depletion is more likely to follow an episode of cor pulmonale.

Adult↗