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Biomedical subjects

A Canas

Publications and source records attributed to A Canas.

4 recordsLinked to original sources
PubMed2000

Tall stature in familial glucocorticoid deficiency.

OBJECTIVE: Familial glucocorticoid deficiency (FGD) has frequently been associated with tall stature in affected individuals. The clinical, biochemical and genetic features of five such patients were studied with the aim of clarifying the underlying mechanisms of excessive growth in these patients. PATIENTS AND METHODS: Five patients with a clinical diagnosis of FGD are described in whom the disorder resulted from a variety of novel or previously described missense or nonsense mutations of the ACTH receptor (MC2-R). All patients demonstrated excessive linear growth over that predicted from parental indices and increased head circumference. RESULTS: Growth hormone and IGF-I-values were normal. Growth charts suggest that the excessive growth is reduced to normal following the introduction of glucocorticoid replacement. A characteristic facial appearance including hypertelorism, marked epicanthic folds and prominent frontal bossing was noted. CONCLUSIONS: These findings indicate that ACTH resistance resulting from a defective ACTH receptor may be associated with abnormalities of cartilage and/or bone growth independently of the GH-IGF-I axis, but probably dependent on ACTH actions through other melanocortin receptors.

Adrenocorticotropic Hormone↗
PubMed1990

Leydig cell function in adolescent boys with varicoceles.

The incidence of varicoceles in adolescent boys ranges from 5% to 19.5%. We studied five adolescent boys aged 17 to 20 years with visible left-sided varicoceles. All of them had public hair and testicular volumes between 20 to 25 mL and had achieved stage V of pubertal development. Serum gonadotropin response to the intravenous administration of 100 micrograms of gonadotropin-releasing hormone (GnRH) and testosterone response to the administration of 2,000 IU human chorionic gonadotropin (hCG) daily for 3 days before and 3 months after varicocelectomy were measured. Basal levels of both gonadotropins were in the pubertal range, and there was no significant difference between serum levels before and after varicocelectomy. Both gonadotropins, however, showed increased responses to the administration of GnRH (luteinizing hormone [LH]: basal, 12.0 +/- 5.1 mIU/mL; peak, 105.0 +/- 36.0 mIU/mL; follicle-stimulating hormone [FSH]: basal, 11.6 +/- 4.2 mIU/mL, peak, 60.0 +/- 18.0 mIU/ml) that decreased after varicocelectomy (LH: basal, 14.3 +/- 6.0 mIU/mL; peak, 58.6 +/- 12.0 mIU/mL; FSH: basal, 6.8 +/- 4.6 mIU/mL; peak, 38.0 +/- 8.1 mIU/mL). Serum testosterone response to hCG was also significantly improved by varicocelectomy (testosterone peak: before, 780 +/- 210 ng/dL; after, 1850 +/- 170 ng/dL). Testicular biopsy specimens showed no histologic abnormalities and normal spermatogenesis. Endocrine evaluation in adolescent boys with varicoceles could detect an early Leydig cell dysfunction that could be corrected by varicocelectomy.

Adolescent↗
PubMedDate not supplied

Effect of finasteride on human testicular steroidogenesis.

We studied the testicular function and some androgen-mediated events in 22 males (16-30 years of age) with male pattern baldness that was treated with finasteride (10 mg once daily) for 2 years. Patients were evaluated every 3 months. Prostatic volume was determined in six subjects by endorectal ultrasound scans. Serum gonadotropin, prostate-specific antigen (PSA), and sex hormone levels were determined basally and periodically during the treatment period. Fourteen subjects underwent gonadal stimulation with human chorionic gonadotropin (hCG), and the gonadotropin response to gonadotropin releasing hormone (GnRH) was determined in eight subjects, prior to and after 2 years of therapy. Finasteride treatment resulted in an improvement in the male pattern baldness and prostatic shrinkage that was associated with an increase in serum testosterone levels (17.2 +/- 2.5 vs. 26.3 +/- 1.7 nmol/L) and a decrease in dihydrotestosterone (DHT) levels (1.45 +/- 0.41 vs. 0.38 +/- 0.10 nmol/L), causing a marked increase in that testosterone/DHT ratio. A significant increase in the serum levels of androstenedione (3.67 +/- 0.49 vs. 7.05 +/- 0.70 nmol/L) and estradiol (132 +/- 44 vs. 187 +/- 26 pmol/L) was also noted, whereas androstanediol glucoronide (33.3 +/- 6.4 vs. 10.7 +/- 4.5 pmol) and PSA (1.6 +/- 0.6 vs. 0.4 +/- 0.1 ng/ml) were significantly decreased. No changes in basal or stimulated levels of gonadotropin were observed. There was a significant increase in the testosterone response to hCG during finasteride therapy (delta: 16.7 vs. 35.5 nmol/L) that could be explained, at least in part, by the reduction of testosterone metabolism resulting from the blockage induced by finasteride. The decrease in the androstenedione to testosterone and estrone to estradiol ratios observed after hCG treatment, however, strongly suggests increased activity of the 17-ketosteroid reductase enzyme and an improvement of the testicular capacity for testosterone production.

Adult↗