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C Foresta

Publications and source records attributed to C Foresta.

At least 109 records · Page 6Linked to original sources
PubMed1992

Extracellular ATP is a trigger for the acrosome reaction in human spermatozoa.

We tested the effect of extracellular adenosine 5'-triphosphate (ATPo) on the activation of human spermatozoa. ATPo, in a concentration range from 50 microM to 5 mM, induced the acrosome reaction, which, at the optimal concentration of 2.5 mM, was maximal (30-35% of spermatozoa activated) within 60 min of the addition of the nucleotide. At the end of this incubation in the presence of ATPo no decrease in cell motility and viability was observed. Among other purine/pyrimidine nucleotides only the ATP analogue adeny-5'-lyl imidodiphosphate was effective (70% of ATP); a weak (10% of ATP) effect was also observed with CTP and the ATP analogues adenosine 5'-(beta gamma-methylene)triphosphate and adenosine 5'-O-(thiotriphosphate). ATPo did not cause Ca2+ release from intracellular stores, nor it caused Ca2+ influx from the extracellular milieu; on the contrary, it caused a clear, albeit slow, plasma membrane depolarization. ATPo-activated spermatozoa showed a nearly 100% success rate in the standard hamster egg fertilization test. Our results describe a new effect of ATPo in human spermatozoa with relevant potential applications in fertility studies.

Acrosome↗
PubMed1992

Assessment of testicular cytology by fine needle aspiration as a diagnostic parameter in the evaluation of the azoospermic subject.

OBJECTIVE: To investigate whether testicular cytology by fine needle aspiration (FNA) may be considered a diagnostic parameter in the evaluation of the azoospermic subject. DESIGN: Cytologic smears were obtained using a 23-G needle, stained with May-Grünwald-Giemsa stain and examined under a light Orthoplan microscope (Wild, Leitz, Germany) for qualitative and quantitative analysis. PATIENTS: Fifty-four azoospermic patients were analyzed, and the findings were compared with those obtained from 40 normozoospermic infertile subjects used as controls. MAIN OUTCOME MEASURE(S): Two hundred spermatogenic cells were counted and classified at the various steps of spermatogenesis. Spermatic index and Sertoli index provided further elucidations and more comprehensible results. RESULTS: No sign of traumatization was observed. Cytologic analysis was proved to have high statistical reproducibility (P less than 0.01 for spermatogonia and secondary spermatocytes and P less than 0.001 for the other cell types, when compared between differential counts) and permitted identification of different situations associated with azoospermia: Sertoli cell-only syndrome, germ depopulation (hypospermatogenesis), spermatogonial arrest, spermatidic arrest, and obstructive azoospermia. These findings agreed with clinical and hormonal parameters and with the results of bilateral surgical biopsies, when performed. CONCLUSIONS: The results support use of FNA of the testis as a noninvasive diagnostic parameter for the assessment of azoospermic subjects.

Adult↗
PubMed1992

Assessment of testicular cytology by fine needle aspiration as a diagnostic parameter in the evaluation of the oligospermic subject.

OBJECTIVE: To investigate whether testicular cytology by fine needle aspiration may be considered a diagnostic parameter in the evaluation of the oligospermic subject. DESIGN: Cytologic smears were obtained using a 23-gauge needle, stained with May-Grünwald-Giemsa stain and examined under a light Orthoplan microscope (Wild Leitz, Wetzlar, Germany) for qualitative and quantitative analysis. PATIENTS: One hundred sixty-six oligospermic patients were analyzed, and the findings were compared with those obtained from 40 normozoospermic infertile subjects used as controls. MAIN OUTCOME MEASURE(S): At least 200 spermatogenic cells were counted per slide and classified at the various steps of spermatogenesis. Because the number of Sertoli cells may be considered as a constant per unit of tubular length, Sertoli cells:spermatogenic cells ratio (termed Sertoli index) provided further elucidation and more comprehensible results. RESULTS: The procedure provided no sign of traumatization. The cytologic analysis permitted identification of different classes of oligospermic subjects, characterized by the following specific cytologic pictures: [1] bilateral or [2] unilateral germ depopulation (hypospermatogenesis), associated with maturation abnormalities of the first steps of spermatogenesis on both testes; [3] difficult maturation of the immature germ cells (spermatogonial or spermatocytic arrest); [4] ineffective spermiogenesis (spermatidic arrest); [5] normal maturation of the germ line in the presence of oligospermia, resulting from a transient acute damage on the spermatogenic line. Plasma levels of FSH and the testicular volumes agree with the cytologic picture of each group of patients. CONCLUSIONS: The results support use of fine needle aspiration of the testis as a minimally invasive diagnostic parameter for the assessment of oligospermic subjects.

Adult↗
PubMed1992

Sperm nuclear instability and staining with aniline blue: abnormal persistence of histones in spermatozoa in infertile men.

During mammalian spermiogenesis, replacement of the somatic histones by basic proteins, the protamines, allows normal sperm nuclear condensation. In this study we have evaluated the degree of chromatin compaction in spermatozoa from 191 infertile subjects, affected by different testicular disorders, compare with that in 50 fertile sperm donors (controls). In infertile men, there was a higher percentage of unstable spermatozoa after incubation with sodium dodecyl sulphate (SDS) and of stained spermatozoa after staining with aniline blue (P less than 0.001 vs. controls). Furthermore, a positive linear correlation was found between SDS-unstable spermatozoa and stained spermatozoa (P less than 0.001), suggesting that sperm instability was related to a defect in histone-replacement by sperm-specific nucleoproteins, protamines. When the patients were considered according to pathology, high sperm nuclear instability and a high percentage of stained spermatozoa were detected in groups affected by varicocele, idiopathic infertility and in patients with a history of unilateral cryptorchidism. In the latter group the same alterations were observed even when the cryptorchid testis had been removed during surgery. In the group with a past history of mumps orchitis these parameters did not show any difference when compared with controls.

Adult↗
PubMed1992

Evidence for specific binding and stimulatory effects of recombinant human erythropoietin on isolated adult rat Leydig cells.

The presence of specific binding of recombinant human erythropoietin and its effect on testosterone production were evaluated in isolated intact adult rat Leydig cells. Maximal specific binding was observed after 135 min incubation at 34 degrees C. Scatchard analysis of the binding data revealed two distinct classes of binding sites for [125I]-recombinant human erythropoietin with dissociation constant of (Kd1) 1.9 x 10(-10) mol/l and (Kd2) 1.37 x 10(-8) mol/l respectively and binding capacity of (Bmax1) 12.3 fmol/10(6) cells and (Bmax2) 42.8 fmol/10(6) cells, respectively. GnRH, hCG, IGF-I and EGF did not induce any modification of recombinant human erythropoietin-specific binding. Recombinant human erythropoietin added to isolated adult rat Leydig cells exerted a stimulatory effect on testosterone production reaching its maximal effect at the dose of 10(-10) mol/l (testosterone production from 14.9 +/- 1.7 to 45.1 +/- 6.2 pmol/10(6) cells/3 h). Addition of anti-recombinant human erythropoietin serum completely blocked the recombinant human erythropoietin-stimulated testosterone production. These results show that purified adult rat Leydig cells possess recombinant human erythropoietin specific binding, and suggest that this glycoprotein directly influences rat Leydig steroidogenesis.

Animals↗
PubMed1991

Evidence for the involvement of sperm angiotensin converting enzyme in fertilization.

Recently it has been observed that ejaculated human sperm possess high angiotensin converting enzyme (ACE) activity and that this enzyme is released during the process of capacitation. This observation raises the possibility that ACE may be involved in the fertilization process. To verify this hypothesis, we tested the effects of a potent ACE inhibitor, Captopril, on acrosome reaction induced by capacitating medium (3.5% HSA-added BWW) and on ability of human capacitated spermatozoa to penetrate zona-free hamster oocytes. Addition of Captopril (100 nmol l-1) modified neither sperm motility nor viability at any time considered, but significantly reduced the acrosome reaction percentages of sperm incubated in capacitating medium. Furthermore, Captopril significantly reduced the percentage of penetrated oocytes. The mean penetration rates both in the absence and presence of Captopril were 65.5 +/- 4.9% and 26.9 +/- 2.3% (P less than 0.001) respectively. These findings provide evidence that sperm release of ACE during capacitation may have a physiological role in the regulation of the mechanisms that allow sperm acrosome reaction and thus fertilizability.

Acrosome↗
PubMed1991

Stimulatory effects of alpha-hANP on testosterone secretion in man.

Several recent observations suggest that atrial natriuretic peptides (ANP) can modulate steroidogenesis in isolated rat Leydig cells. At present, it is unknown whether ANP influence human testicular steroidogenesis. We therefore evaluated the effects of alpha-human ANP (hANP) administration on testosterone plasma levels in peripheral and internal spermatic venous blood of young men (catheterized for contrast study of varicocele). Six subjects were injected with 100 micrograms alpha-hANP in the cubital vein. Six different patients similarly received 50 micrograms LHRH. Three controls received 2 ml saline. Plasma LH, FSH, and testosterone were then determined 15 min before, at time of injection, and 15, 30, 45, and 60 min thereafter in spermatic vein and peripheral venous blood, as well as at 120 min in peripheral blood. LHRH--induced LH increase was followed by a marked increase of spermatic vein testosterone concentrations, but the peripheral testosterone concentration did not increase. Similarly, alpha-hANP administration did not affect peripheral testosterone and LH concentrations, but significantly increased spermatic vein testosterone levels (P less than 0.01). Our findings demonstrate that alpha-hANP exerts its stimulatory effect on testicular steroidogenesis in man without modifying gonadotropin secretion, suggesting that alpha-hANP may directly influence Leydig cell function.

Adolescent↗
PubMed1990

Immunomagnetic method to select human sperm without sperm surface-bound autoantibodies in male autoimmune infertility.

Using supermagnetic polymer microspheres coated with anti-immunoglobulins, spermatozoa without autoantibodies bound on their surface can be isolated from a sperm population showing a variable percentage of cells with autoantibodies bound on their surface. This simple technique seems to induce no modification of semen qualities; therefore, the concentration of sperm after immunomagnetic separation might be useful for in vivo or in vitro insemination in infertile couples with autoimmune male infertility.

Autoantibodies↗
PubMed1989

Evidence for a dopaminergic involvement in the inhibitory effect of alpha human natriuretic peptide on prolactin in man.

Recently, it has been suggested that Atrial Natriuretic Peptides (ANP), as well as peripheral hormones, may have a role as central neurotransmitters or neuromodulators, and in humans it has been observed that alpha human ANP inhibits prolactin secretion. In this study, on 12 normal adult males, we evaluated the effects of ANP on the prolactin release induced by TRH and by the dopaminergic blocker sulpiride. Alpha-hANP administration was followed by a significant fall of prolactin plasma levels but did not influence TRH-induced prolactin response. Nevertheless, sulpiride-induced prolactin secretion was significantly lower after Alpha-hANP administration than after placebo pre-treatment (p values ranging between 0.01 and 0.001). Our results suggest that in man Alpha-hANP has no direct influence on lactotrope cells in inhibiting prolactin secretion, but seems to involve activation of the hypothalamic dopaminergic system.

Adult↗
PubMed1988

Effect of L-carnitine on motility and acrosome reaction of human spermatozoa.

L-carnitine added to the suspension medium decreases the glucose-sustained progressive motility of human spermatozoa. Addition of 20 mM L-carnitine to the capacitation medium causes an inhibition of the occurrence of the acrosome reaction parallel to a viability enhancement and negligible changes of the cellular content of ATP. The cellular efflux of glutamate-oxaloacetate transaminase was also inhibited by L-carnitine. A possible role of L-carnitine on membrane stability and metabolism of spermatozoa is briefly discussed.

Acrosome↗
PubMed1988

Effects of atrial natriuretic factor (ANF) on rat testicular steroidogenesis in vitro.

The aim of this study was to evaluate the effects of rat atrial-peptide type II (rAP-II) on testicular steroidogenesis by isolated adult rat Leydig cells. rAP-II stimulates testosterone secretion. The maximal stimulatory effects of rAP-II on testosterone production occurred at the dose of 10(-11) M. At the same dose this peptide stimulates androstenedione and dehydroepiandrosterone-sulphate production, two important testosterone precursors of delta-4 and delta-5 steroidogenetic pathways, respectively. At higher doses, 10(-9) and 10(-7) M, the stimulatory effect of rAP-II on testosterone secretion is strongly declined, on androstenedione secretion is abolished, whereas on dehydroepiandrosterone-sulphate secretion remains unaffected. These data suggest that rAP-II at low doses exerts a stimulatory effect on the early steroidogenetic step by isolated adult rat Leydig cells. At higher doses this peptide seems to influence the testicular steroidogenesis, probably exerting a limiting reaction step involving the 3-beta-OH-steroid-dehydrogenase activity.

Androstenedione↗
PubMed1987

Angiotensin-converting enzyme content of human spermatozoa and its release during capacitation.

In this study, we demonstrated, by using known detergents, the presence of angiotensin-converting enzyme (ACE) within human spermatozoa. We determined that maximal angiotensin-converting activity is expressed by sperm incubated in capacitating conditions, whereas this activity is negligible in saline-incubated spermatozoa. We further demonstrated that not acrosomes but cytoplasmic residues contain ACE. Because follicular fluid provides the necessary conditions for a maximal angiotensin-converting activity and for capacitations' metabolic activation, we hypothesize that ACE may play its physiologic role within the female reproductive tract.

Adult↗
PubMed1987

Reduced calcitonin reserve in young hypogonadic osteoporotic men.

Calcitonin is a potent inhibitor of bone resorption and in both sexes, plasma levels progressively decrease with age: therefore, a relative deficiency of calcitonin may be involved in the pathogenesis of osteoporosis in the elderly. Calcitonin plasma levels of young hypogonadic men with osteoporosis are significantly lower than controls: the hypothesis that the decreased calcitonin plasma levels in the elderly are due to a reduced secretory capacity of the "C" cells of the thyroid gland, related to age, does not explain the low calcitonin plasma levels found in young hypogonadic osteoporotic men. Our hypothesis is that gonadal steroid deficiency may participate in the mechanisms regulating calcitonin secretion. Therefore, we studied ten males affected by hypogonadotropic hypogonadism and ten normal men, of comparable age, as controls: we measured plasma levels of testosterone, 17 beta estradiol, androstenedione and calcitonin, and the response of calcitonin to an i.v. bolus of pentagastrin, a well known "C" cells stimulatory drug. Testosterone and calcitonin plasma levels and the response of calcitonin to pentagastrin were also evaluated after 6 months of replacement therapy with testosterone. Basal levels of testosterone, 17 beta estradiol, androstenedione and calcitonin, and the response of calcitonin to pentagastrin, are significantly lower in our patients than in controls, demonstrating that hypogonadotropic hypogonadic subjects have a lower secretory reserve of calcitonin. After testosterone therapy the basal calcitonin plasma levels and its response to pentagastrin stimulus did not differ from controls, suggesting that gonadal steroids influence the calcitonin secretion and reserve. Our data cannot clarify whether osteoporosis of hypogonadotropic hypogonadic patients is related to androgen or estrogen deficiency; however, they suggest that the mechanisms by which gonadal steroid influence bone metabolism may involve calcitonin secretion.

Adult↗
PubMed1987

Role of gonadal steroids in the serotoninergic control of prolactin secretion in men.

The physiological regulation of PRL secretion seems to involve the central serotonin system, since plasma PRL levels are enhanced by serotoninergic agonists and serotonin re-uptake blockers. The aim of this study was to evaluate whether the influence of oestrogens on PRL is mediated by the hypothalamic serotonin system. The PRL response to fenfluramine, a serotonin agonist that releases the amine and inhibits its re-uptake, was assessed in 10 normal men (aged 18-25 years) and in six castrated men (aged 18-24 years). In both groups, the effect of fenfluramine on PRL secretion was also evaluated on the sixth day after receiving clomiphene citrate, an oestrogen antagonist and partial agonist. In castrated men, fenfluramine administration was also performed on the seventh day after the last dose of testosterone enanthate (200 mg i.m. every 3 weeks for 4 months). Our results demonstrate that in normal men fenfluramine treatment significantly enhances plasma PRL levels, and clomiphene citrate treatment significantly reduces this effect. In castrated men, fenfluramine is also able to enhance PRL secretion but to a lesser extent; after clomiphene citrate treatment the increase of plasma PRL levels induced by fenfluramine rises to the normal range. We therefore suggest that in man oestrogens and aromatizable androgens influence PRL secretion at least in part by involving the activation of the hypothalamic serotonin system.

Adolescent↗
PubMed1987

Specific binding and steroidogenetic effects of atrial natriuretic factor (ANF) in Leydig cells of rats.

Atrial natriuretic factors (ANF) may influence testicular steroidogenesis. This study was conducted to evaluate the presence of specific ANF-binding on isolated adult rat Leydig cells and the effects of ANF on testosterone production. Indirect immunofluorescence technique demonstrates that adult rat Leydig cells possess specific ANF-binding and that rAP-II strongly stimulates the testosterone production. rAP-II exerts its maximal stimulatory effect on the testosterone secretion at low doses (10(-11) M), corresponding at the physiological plasmatic concentration in the adult normal rat. High doses (10(-9)-10(-7) M) of rAP-II show a decline in the stimulatory effect on testosterone secretion. Our data suggest that rAP-II influences the testicular steroidogenesis by a receptorial mechanism; the biphasic effect of rAP-II on the testosterone production may be related to an acute receptorial desensitization phenomena.

Animals↗
PubMed1986

Evidence for serotoninergic system involvement in opioid control of luteinizing hormone secretion in man.

Endogenous opioid peptides tonically inhibit LH by acting on hypothalamic mechanisms which regulate LHRH secretion. Opiates increase hypothalamic serotonin turnover but the involvement of the serotoninergic system in the opioid mechanisms regulating LH secretion in man is not clear at present. This study was designed to evaluate whether the tonic inhibitory effect on LH secretion induced by opiates involves the serotoninergic system. We have studied 10 healthy young men (aged 20-28 years). Five subjects were infused with naloxone (10 mg/h for 3 h) before and 120 min after fenfluramine administration (60 mg orally) on two different occasions. In five other subjects naloxone was infused before and after metergoline pretreatment (8 mg on first and second day and 4 mg on the third day, orally, at 0 time of naloxone infusion). After fenfluramine, naloxone infusion failed to induce any increase in LH plasma levels; metergoline pretreatment significantly enhanced the naloxone-induced LH increase. These data suggest that in man a hypothalamic serotoninergic system may be involved in the opioid mechanisms regulating LH secretion.

Adult↗