Biomedical subjects

H Raff

Publications and source records attributed to H Raff.

112 records · Page 7Linked to original sources

PubMedDate not supplied

Adrenocortical function after acute carbon monoxide exposure in humans.

The effect of acute carbon monoxide (CO) exposure on plasma adrenocorticotrophic hormone (ACTH), renin activity (PRA), aldosterone, and cortisol levels was studied in patients approximately 80-90 min after removal from the scene of exposure. Nine patients had carboxyhemoglobin (COHb) levels below 15%. Seven patients had COHb levels that exceeded 15% (Group II). Plasma ACTH, cortisol, and aldosterone levels were significantly higher in Group II (elevated COHb). Plasma cortisol and aldosterone levels were appropriate for the levels of ACTH and PRA achieved. We concluded that (a) acute carbon monoxide poisoning leads to elevated plasma corticosteroid levels, and (b) the adrenal gland appears to function normally acutely after exposure to carbon monoxide.

Adolescent↗

PubMedDate not supplied

Correlation of plasma angiotensin II concentration and plasma renin activity during acute hypoxia in dogs.

The effects of isocapnic hypoxia on plasma renin activity (PRA) and angiotensin II (AII) concentration were studied in anaesthetized, artificially ventilated dogs. Regression analysis of plasma AII concentration vs PRA, both measured by radioimmunoassay (RIA), was used as an index of converting enzyme activity in vivo. PaO2 decreased from 82 to 30 mmHg but regression analysis did not reveal any inhibition of AII production within the limits of detection of this method (less than 20% inhibition). We conclude that systemic converting enzyme activity, assessed by in vivo measurement and correlation of PRA and AII, is not inhibited by severe hypoxia.

Acute Disease↗

PubMedDate not supplied

Aldosterone responses to ACTH during hypoxia in conscious rats.

This study examined the aldosterone response to physiological ACTH infusion (4 ng/kg per min) and pharmacological ACTH injection (1.8 microgram) in conscious Long-Evans rats at 42 h of normoxia (21% O2) or hypoxia (10% O2). Hypoxia per se (no exogenous ACTH) significantly decreased control aldosterone levels despite elevated endogenous plasma ACTH). Hypoxia attenuated the aldosterone responses to ACTH infusion but not to ACTH injection. It was concluded that hypoxia attenuates aldosterone responses to small increases in ACTH, and large increases in ACTH can override this apparent decrease in adrenocortical sensitivity.

Adrenocorticotropic Hormone↗

PubMedDate not supplied

Factitious Cushing's syndrome: discovery with use of a sensitive immunoradiometric assay for corticotropin.

Factitious Cushing's syndrome is an unusual problem that may be clinically and biochemically indistinguishable from endogenous hypercortisolism. Results of biochemical studies may be misleading because of cross-reactivity of synthetic corticosteroids or their metabolites with plasma or urine cortisol. Because of its lack of specificity, radioimmunoassay (RIA) for corticotropin (adrenocorticotropic hormone or ACTH) may not show completely suppressed results in patients with surreptitious use of glucocorticoids. A new sensitive and specific immunoradiometric assay (IRMA) for ACTH demonstrates reliably suppressed levels after administration of glucocorticoids. In this report, we describe a 37-year-old woman with typical clinical and biochemical features of ACTH-dependent hypercortisolism. Metabolic evaluation had shown urinary free cortisol excretion of 7,499 nmol/day and plasma ACTH-RIA levels of 13.2 and 33.0 pmol/L on two separate occasions. The use of IRMA for the measurement of ACTH during inferior petrosal sinus sampling revealed a very low peripheral ACTH concentration (=0.4 pmol/L) and a considerably blunted response to ovine corticotropin-releasing hormone, findings that suggested ACTH-independent Cushing's syndrome. Plasma samples obtained during inferior petrosal sinus sampling were assayed for prednisolone and showed a concentration of 360 nmol/L; thus, the presence of factitious Cushing's syndrome was confirmed. Some commercial ACTH-RIA measurements may be unreliable in distinguishing ACTH-dependent from ACTH-independent hypercortisolism. ACTH-IRMA levels are low in patients with ACTH-independent Cushing's syndrome and will be helpful in identifying factitious Cushing's syndrome.

Journal Article↗