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Biomedical subjects

D B Cook

Publications and source records attributed to D B Cook.

At least 55 records · Page 3Linked to original sources

Domperidone: a novel agent for the investigation of anterior pituitary function and control in man.

Administration of the novel agent domperidone (10 mg iv), which combines the properties of specific dopamine receptor blockade and inability to cross the blood-brain barrier, leads to acute and significant TSH and PRL release in man. This suggests that the in vivo site of action of endogenous dopamine in the inhibitory control of these two hormones is either the anterior pituitary or median eminence, since these tissues lie outside the blood-brain barrier. This class of drug is of potential value both clinically and experimentally in the investigation of anterior pituitary control mechanisms.

Autoimmune Diseases↗

Heparin resistance and decreased hepatic triglyceride hydrolase release during long-term estrogen-progestin treatment.

These studies were undertaken to define the mechanism for the depression of post-heparin triglyceride hydrolase activity in women treated with estrogen-progestin oral contraceptives. Six treated and six control women were studied. Total, protamine-inhibited, and protamine-resistant triglyceride hydrolase activities were measured after six different intravenous doses of heparin in each subject in order to determine the dose-response relationships for lipase release. As has been reported during short-term treatment with estrogens, long-term treatment with oral contraceptive agents is accompanied by selective depression of protamine-resistant (hepatic) lipase activity. This depression can be partly reversed by the administration of large heparin doses, but maximally releasing heparin does fail to restore postheparin protamine-resistant activity to control values. These data are compatible with the idea that the releasable pool of hepatic triglyceride hydrolase activity is diminished in women who receive oral contraceptive agents and that the pharmacokinetics of its release are altered in such a way that only relatively high concentrations of heparin displace the enzyme from this pool.

Adult↗

Seasonal variation of serum 25-hydroxyvitamin D in patients with chronic renal failure treated by regular haemodialysis.

Serum 25-hydroxyvitamin D was measured by a competitive protein-binding assay in 44 normal subjects, 60 uraemic patients on regular haemodialysis at different times of the year and in 13 non-dialyzed uraemic patients. The results obtained indicate that uraemic patients on regular haemodialysis have a mean serum 25-hydroxyvitamin D concentration comparable to controls and that they also exhibit a seasonal variation with a significant reduction during the winter months. However, serum 25-hydroxyvitamin D concentration remained essentially within the normal range and did not reflect the increased incidence of osteomalacia in these patients. In the 13 non-dialyzed uraemic patients, serum 25-hydroxyvitamin D concentrations were lower than in the dialyzed patients, but the explanation is not yet clear. This reduction in serum 25-hydroxyvitamin D was not accompanied by any osteomalacia. The results indicate that deficiency of 25-hydroxyvitamin D in our patients on regular haemodialysis is uncommon and clearly not the explanation of dialysis osteomalacia.

Carrier Proteins↗

Effects of nomifensine, an inhibitor of endogenous catecholamine re-uptake, in acromegaly, in hyperprolactinaemia, and against stimulated prolactin release in man.

1. Nomifensine, an inhibitor of endogenous catecholamine re-uptake, did not affect the growth hormone (GH) or prolactin levels in patients with acromegaly or hyperprolactinaemia. It does not, therefore, have any therapeutic role in these conditions at the dosage used in this study. 2. It had no effect on thyrotrophin-releasing hormone (TRH)-induced thyrotrophin (TSH) or prolactin release in males, yet caused marked suppression of monoiodotyrosine (MIT)-induced prolactin release in males but not in females. 3. The significant suppression of MIT-induced prolactin release in males is likely to reflect the dopamine (DA) agonist activity of the drug and its lack of effect in the other situations tested could be dose related. 4. It is proposed that the difference in male and female patterns of prolactin response to MIT after nomifensine, could be due to a "damping" effect of oestrogen on the hypothalamic dopaminergic system.

Acromegaly↗

Effect of surgical trauma on plasma concentrations of cyclic AMP and cortisol.

The response of plasma cortisol and cyclic AMP concentrations to surgical trauma was examined in 7 general surgical patients. Five patients made uncomplicated recoveries and showed peak cortisol levels at 6 hours postoperatively, returning to normal by 24 hours. On patient developed postoperative pneumonia and the plasma cortisol remained elevated up to 48 hours, and the final patient showed no cortisol response at all. The plasma cyclic AMP concentrations showed a consistent rise during the operation itself, which was statistically significant when compared with preoperative levels (P less than 0.0125). Concentrations had fallen to normal by 6 hours in all the cases, except in the patient who developed pneumonia, where the plasma cyclic AMP also showed a prolonged elevation. The significance of these findings requires further elucidation, but the temporal relationship of the cyclic AMP and cortisol peaks would support the hypothesis that cyclic AMP may play a part in the mediation of ACTH release following surgical trauma.

Adrenocorticotropic Hormone↗

Stress effect of antilymphocyte serum.

Antilymphocyte serum prepared in the rabbit against guinea-pig lymph node cells produces a sustained weight loss when injected into normal guinea-pigs over 14 days, compared with a very transient loss produced by normal rabbit serum. Antilymphocyte serum also produces a much greater increase in plasma cortisol level than normal rabbit serum. Part of this effect may be due to adrenal stimulation, and further studies of its activity in adrenalectomized animals are suggested.

Adrenalectomy↗