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Biomedical subjects

A Fabbrini

Publications and source records attributed to A Fabbrini.

At least 19 recordsLinked to original sources
PubMed1992

Human Sertoli cells in vitro: morphological features and androgen-binding protein secretion.

Sertoli cells play a pivotal role in the regulation of spermatogenesis as they provide the anatomical basis of the blood-testis barrier. In the present paper we report some results of our studies on the ultrastructural features, the responsiveness to FSH, and the ability to secrete androgen-binding protein (ABP) of human Sertoli cells in vitro. The nucleus showed the characteristic foldings of the nuclear membrane, scattered chromatin, and a fibrillar nucleolus. In the cytoplasm Charcot-Boettcher crystals were present and active phagocytic activity was documented by the presence of vacuoles containing lipids and cellular debris. Human Sertoli cells in culture responded to FSH with a maximal rise in cAMP that was approx. 3-fold. This response to FSH is comparable to that reported for the adult rat but lower than that of the immature rat, and suggests that human as well as rat Sertoli cells could have a reduced response to FSH since sexual maturation was achieved. As no evidence has been reported on ABP secretion by human Sertoli cells in culture we evaluated the concentration of this protein in the Sertoli cell spent media. Human Sertoli cells in culture produced ABP and the response to FSH was dose-related. The Kd value of human ABP (hABP) was approx. 7.5 nM, being slightly higher than that of the rat ABP and an order of magnitude different from that of sex hormone-binding globulin (SHBG) present in human plasma. We also measured the association and dissociation rates of dihydrotestosterone-hABP complexes and the Kd/Ka ratio was very close to the value of Kd of the Scatchard analysis. The differences between hABP and SHBG may open the way to the selective measurement of ABP in many conditions of male infertility.

Androgen-Binding Protein↗
PubMed1987

Lactate dehydrogenase and malate dehydrogenase of Sertoli cells in rats.

Lactate-dehydrogenase (LDH) and malate-dehydrogenase (MDH) activities and isozyme patterns of maturing Sertoli cells were investigated in cultured cells obtained from 2-5-week-old rats. Both enzymes, and more strikingly LDH, increased between 2 and 3 weeks of age. LDH isozyme complement included all five isozymes and, in the more mature rats, had a shift toward the isoforms rich in subunit. These data are consistent with an increasing production of lactate/pyruvate and with a finer regulation of this production occurring during the maturing of Sertoli cells. Since lactate/pyruvate are important energy substrates for germ cells, the changes of LDH activity and isozyme patterns of maturing Sertoli cells support their nutritional role in the seminiferous epithelium.

Animals↗
PubMed1986

Quantitative evaluation of Leydig cells in testicular biopsies of men with varicocele.

A quantitative analysis of Leydig cells was performed in 23 testicular biopsies of men with left varicocele and sperm count ranging from zero to 95,000 sperm/mm3. The oligozoospermic patients had more Leydig cells and higher FSH and LH serum levels than the patient group with more than 10,000 sperm/mm3. The Leydig cell density appeared tightly correlated (p less than 0.01) with the serum level of LH. In oligozoospermic subjects, an altered Leydig cell function could trigger an increased LH secretion; this seems likely to be responsible for the stimulation of interstitial cells resulting in an exaggerated recruitment of mature Leydig cells from their precursors. The comparative analysis of left and right testes failed to show differences in Leydig cell density and spermatogenesis in normozoospermic and oligozoospermic patients. This suggests that the two testes are equally involved by a possible, although unknown, detrimental effect of left side varicocele.

Adult↗
PubMed1985

Insulin resistance and secretion in polycystic ovarian disease.

In order to verify the relationship between insulin resistance and hyperandrogenism in Polycystic ovary disease (PCOD), circulating levels of insulin in response to oral glucose tolerance test (OGTT) were assessed in 23 PCOD patients and 10 matched control subjects without obesity, acanthosis nigricans and impaired glucose tolerance. In PCOD patients serum total testosterone (T), dehydroepiandrosterone sulfate (DHEA-S), LH and LH/FSH ratio were significantly higher than in control subjects; whereas urinary 17-ketosteroids (17-KS) and glycemic response to OGTT were not different. PCOD patients were clearly hyperinsulinemic before and during OGTT compared to the control group: mean +/- SD basal insulin (Io) (23.4 +/- 10.3 vs 11.3 +/- 4.6 microU/ml, p less than 0.001) and the sums of insulin levels (sigma I) during OGTT (341.4 +/- 148.9 vs 162.2 +/- 56 microU/ml, p less than 0.001). In the two groups serum T, but not DHEA-S, LH, urinary 17-KS and the degree of obesity, was strongly associated with Io (r = 0.458, p less than 0.01) and sigma I (r = 0.419, p less than 0.02), as well as with insulin resistance as assessed by basal (r = 0.425, p less than 0.02) and postglucose challenge (r = 0.384, p less than 0.05) insulin to glucose ratio. These results confirm that the hyperinsulinism and insulin resistance in PCOD is not related to obesity and suggest that the hyperandrogenism may be partially responsible of the observed imbalance in glucose-insulin homeostasis.

Adolescent↗
PubMed1984

Effects of Lonidamine on pituitary-gonadal axis in man.

Lonidamine was given for 3 weeks at the dose of 150 mg three times daily to 6 male cancer patients. Serum follicle-stimulating and luteinizing hormone levels were significantly higher as compared to pretreatment values after 1 and 3 weeks of Lonidamine administration, while testosterone, prolactin, and thyroid-stimulating hormone levels remained unchanged.

Aged↗
PubMed1980

[Gonadotropin response to slow infusion of GN-RH in idiopathic ologospermia. Preliminary findings].

Gn-RH was administered i.v. to infertile patients presenting with idiopathic oligospermia at a constant rate (0,4 microgram) for 4 h. All the patients showed an increased FSH response, and LH levels higher than normal in both the first and the second peak of response. Our data indicate that an increased pituitary sensitivity and reserve of FSH and LH are present in idiopathic oligospermia, suggesting an involvement of both Leydig cells and seminiferous epithelium in this condition.

Adult↗
PubMed1979

[Development and differentiation of the rat epididymis. I: ultrastructural aspects of the peritubular zone].

We investigated the ultrastructural aspects of the peritubular cells of epididymis and their development from birth to adult age. At birth the peritubular zone consisted of polygonal cells which did not differ from other interstitial cells. Cytoplasmic filaments were visible in the cells of the inner layer at day 6. From day 22 the peritubular cells reached the adult aspect. The peritubular cells in the rat epididymis had aspects similar to those of peritubular smooth muscle cells of rat testis, with a more precocious appearance of cytoplasmic filaments. This finding concurs with the observed precocious contractility of epididymis.

Animals↗
PubMed1979

Ultrastructural changes in the seminiferous tubule wall and intertubular blood vessels in human cryptorchidism.

Biopsy material was obtained from adult men whose both testes had descended into the scrotal sac either spontaneously by use of pharmacologic agents or through surgery at age 7--16 yr, and from undescended testes obtained during orchipexy in men 8--40 yr of age. Testes appeared normal until the 10th yr, when progressive alterations were observed with the onset of puberty and through the adult age both in retained testes and cases of testes that descended through chemical or surgical methods before or after puberty. A thickening of the inner and outer acellular layers of the seminiferous tubule wall was due to an accumulation of collagen fibers and microfibrillar material. The basement membrane was also thickened and appeared as a homogeneous or a multilaminar structure. The intertubular blood vessels presented a thickening of the tunica media and a laminar accumulation of basement-membrane-like material.

Adolescent↗