Biomedical subjects

G Romalo

Publications and source records attributed to G Romalo.

21 records · Page 2Linked to original sources

PubMed1987

Androgen binding in cultured human fibroblasts from patients with idiopathic hypospadias.

Androgens stimulate development and growth of the external male genitalia. Since hypospadias represents the most common congenital abnormality in the male newborn and the mechanism of action in this disorder is still unclear, androgen binding was assessed in cultured fibroblasts from biopsies from genital skin of 10 patients with idiopathic hypospadias. For comparison, binding was determined in corresponding samples from 8 males with normal penile development and from 9 patients with known androgen resistance syndromes (testicular feminization, Reifenstein syndrome, pseudovaginal perineoscrotal hypospadias). Finally, binding was measured in 10 samples of nongenital skin. Maximum specific binding (Bmax) in idiopathic hypospadias varied from 3.2 to 15.5 (median 6.6) fmol.mg protein-1. Bmax in samples of persons with normal genital development was between 12.2 and 17.9 fmol.mg protein-1 (median 13.2). Bmax in samples of patients with known androgen resistance syndromes was exactly in the range reported previously in the literature. It is evident that Bmax in samples of patients with idiopathic hypospadias differs significantly (P less than 0.01), (Mann Whitney U-test) from those with normal genital development. Thus it seems reasonable to conclude that in some patients with idiopathic hypospadias the genital defect is caused by receptor deficiency.

Adolescent↗

PubMed1986

Inhibition of androgen receptor binding by natural and synthetic steroids in cultured human genital skin fibroblasts.

The ability of various natural and synthetic steroids (some of which are widely used in clinical practice) to compete with dihydrotestosterone receptor binding in human genital skin fibroblasts was studied. Binding was assessed in fibroblast monolayers after incubation for 1 h at 37 degrees C with 2 nM 3H-dihydrotestosterone in the presence or absence of increasing concentrations of the steroid to be tested. Inhibition constants (Ki) were determined as the concentration of competitor-required for 50% inhibition of 3H-dihydrotestosterone binding. In addition, relative binding activity (RBA) of each test compound was calculated. Each competitor was tested in at least two different cell strains. The concentrations of unlabeled methyltrienolone (a synthetic nonmetabolizable androgen) and dihydrotestosterone for 50% inhibition of 3H-dihydrotestosterone binding were in the same order of magnitude, namely, 2 nM (2.2 respectively, 2.4 nM), whereas the affinity of testosterone was approximately one-fifth that of dihydrotestosterone. Other potent competitors for dihydrotestosterone binding were three progestins (norgestrel, gestoden, and medroxyprogesterone acetate) which have Ki values similar to testosterone. An order of magnitude lower Ki values (around 10(-7) M) were found for the androgen 17 alpha-propylmesterolone, the antiandrogen cyproterone acetate, and the progestin norethisterone acetate. Binding affinities of all other steroids to the androgen receptor were markedly lower and showed the following order of potency: estrogens (estradiol, ethinyl estradiol, diethylstilbestrol) greater than glucocorticoids as well as aromatase inhibitors and potassium canrenoate.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding, Competitive↗

PubMedDate not supplied

Human osteoblast-like cells contain specific, saturable, high-affinity glucocorticoid, androgen, estrogen, and 1 alpha,25-dihydroxycholecalciferol receptors.

Glucocorticoids, androgens, estrogens and 1 alpha,25-dihydroxycholecalciferol (1 alpha,25-(OH)2D3) exert a variety of effects on bone homeostasis. We have measured the receptors for these hormones in cultured human osteoblast-like cells. Specific binding was found with each of the four steroids tested, namely maximum binding capacities, Bmax, of 2,581 (1,368-4,223), 146 (101-237), 176 (20-552), and 387 (290-620) fmol.mg DNA-1 (mean, range) for [3H]dexamethasone, [3H]5 alpha-dihydrotestosterone, [3H]17 beta-estradiol ([3H]E2), and [3H]1 alpha,25-(OH)2D3, respectively. The corresponding apparent dissociation constants were 13.3 (9.2-22.2), 0.43 (0.23-0.94), 0.45 (0.17-0.88), and 0.020 (0.008-0.030) nM, respectively. Both high-affinity, low-capacity and low-affinity, high-capacity specific [3H]E2 binding were demonstrable. In conclusion, we could demonstrate that human osteoblast-like cells contain specific glucocorticoid receptors. In addition specific androgen, estrogen, and 1 alpha,25-(OH)2D3 binding was demonstrated. These cells contain several times more binding sites for dexamethasone than for dihydrotestosterone, estradiol, and 1 alpha,25-(OH)2D3, a feature that might contribute to the marked sensitivity of human bone to glucocorticoids.

Adult↗