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Biomedical subjects

F H Katz

Publications and source records attributed to F H Katz.

At least 37 records · Page 2Linked to original sources
PubMed1977

Hyporeninemia and hypoaldosteronism in diabetes mellitus.

The changes in plasma renin activity (PRA) and plasma aldosterone concentration (PA) in response to postural stimuli were evaluated in 12 patients with stable diabetes mellitus and in five volunteers. Seven diabetic patients had hyperkalemia, and several had renal insufficiency and neurological complications. Five diabetics and had normal serum potassium concentration, a mean creatinine clearance within the normal range, and few complications. PRA and PA were measured in these patients and in the control subjects, all of whom were receiving a diet containing 10 mEq of sodium and 50 mEq of potassium while they were in a supine position, after they were tilted to a 90 degrees position, and after upright posture for two hours. The results indicate that impaired responsiveness of PRA and PA may occur in patients with complicated and those with uncomplicated diabetes and may be responsible in part for a relatively high prevalence of hyperkalemia especially in those diabetic patients with reduced renal function.

Adult↗
PubMed1976

Failure of cyprohepatdine to inhibit vasopressin-stimulated cortisol release in a patient with Cushing's disease.

A case of a 21-year-old woman with Cushing's disease due to a pituitary tumor is described. The patient was treated with cyprohepatadine for 4 weeks immediately following pituitary alpha-particle irradiation. A standard vasopressin test to measure ACTH-mediated cortisol release was performed four times: prior to pituitary irradiation, after irradiation, after 4 weeks of cyproheptadine therapy, and off cyproheptadine for 2 weeks. Cyproheptadine failed to modify vasopressin-stimulated cortisol release in the patient described. This study suggests that cyproheptadine, which has previously been shown to decrease ACTH secretion, probably acts principally at the hypothalamic, rather than at the pituitary level.

Adult↗
PubMed1975

Effects of diphenylhydantoin, phenobarbital, and diazepam on the metabolism of methylprednisolone and its sodium succinate.

The metabolic clearance rates (MCR) of methylprednisolone (MP) (no. = 13) and methylprednisolone-21- Na-hemisuccinate (MPHS) (no. = 6) were studied in normal humans using tritium-labeled steroids. The cumulative appearance of the labeled steroid was examined for the whole urine and for three major urinary fractions. The MCR, half-life, and volume of distribution were, respectively, 383 +/- 72 (SD) liters/day, 165 +/- 49 minutes, and 61 +/- 12 liters for MP, and 234 +/- 37, 160 +/- 19, and 41 +/- 6 for MPHS. Diphenylhydantoin (DPH) administered to 4 subjects increased the MCR of MP from 424 +/- 71 to 977 +/- 132 (P less than 0.01), and decreased the half-life from 149 +/- 44 to 69 +/- 7 (P less than 0.001). Similar effects were found with phenobarbital (PB). Diazepam (DZP) had no effect. Major increases in urinary metabolites after DPH and PB were in the unconjugated ethyl acetate fraction, and this suggests that MP metabolism is significantly altered by hepatic microsomal hydroxylation enzyme induction by DHP and PB, but not DZP. This could occur with the formation of a 6beta-hydroxy derivative which could be readily cleared by the kidney. The urinary pattern of excretion for MPHS was similar to that of MP. The MCR of MPHS was affected to a lesser extent by DPH and PB than was the MCR of MP(P less than 0.01). Therefore, the use of hepatic microsomal hydroxylase inducers should be taken into consideration in clinical states in which MP is being used.

Adult↗
PubMed1975

Combination contraceptive effects on monthly cycle of plasma aldosterone, renin activity and renin substrate.

A post-ovulatory peak of fasting supine plasma aldosterone (PA) preceded or accompanied by an increase in plasma renin activity (PRA) was previously reported. These studies have now been extended in 4 additional normal menstruating women and 4 women taking oestrogen-progestogen oral contraceptive pills (OCP), all studied daily for an entire cycle. Distinct luteal phase increases in PRA were seen in the 4 normals, with 2 also demonstrating a rise in PA. Plasma renin substrate (PRS) was usually unvarying throughout the control cycles. The women taking OCP, on the other hand, all had PA and PRA peaks that were apparent by the fourth or fifth day of taking "the pill". All 4 of the treated women had elevated PRS levels but only one woman showed an increase which preceded the elevation of PRA and PA. Plasma cortisol levels were usually above the normal range in the women taking OCP. This study thus indicates that factors other than oestrogen-induced increased substrate production may be responsible for the PRA and PA rise during OCP treatment. Such factors might be the natri-uretic effects of oestrogens and progestogens or a direct effect on renin secretion by one of these steroids.

Adult↗