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G Forti

Publications and source records attributed to G Forti.

At least 91 records · Page 5Linked to original sources
PubMed1996

Interferon-alpha downregulates expression of the oxytocin receptor in cultured human myometrial cells.

Previous studies in the endometrium of ruminants showed that type I interferon (IFN) prevents oxytocin receptor (OTR) formation. We studied the effect of IFN-alpha on human myometrial cells in culture expressing a high density of biologically active OTR. We found that IFN-alpha induced a 35-50% decrease in OTR mRNA and protein and that this inhibition was time and dose dependent. Maximal inhibition of OTR mRNA was obtained after 2-3 days, whereas 1-(beta-mercapto-beta, beta-cyclopentamethyl-enepropionic acid,2-O-Me-Tyr,Thr4,Orn8,Tyr9-amide)-[125I]vasotocin ([125I]OTA) binding reached a nadir after 3-4 days, with half-maximal inhibitory concentration (IC50) = 1,100 U/ml. Mathematical analysis of multiple homologous competition curves for [125I]OTA indicated that IFN-alpha treatment (5,000 U/ml x 3 days) reduced just the binding capacity (Bmax) without changing the binding affinity. Accordingly, the same treatment with IFN-alpha did not affect the half-maximally effective concentration (EC50) for the oxytocin-induced increase in intracellular calcium but significantly decreased maximal responsiveness (Emax) of myometrial cells to OT stimulation. In conclusion, our data demonstrate, for the first time, a negative regulation by IFN-alpha of the steady-state expression of OTR mRNA in cultured human myometrial cells obtained from nonpregnant uteri. This inhibition was followed by a parallel decrease in both the Bmax for [125I]OTA and Emax for oxytocin, suggesting a decreased OTR protein availability.

Base Sequence↗
PubMed1996

Expression of endothelin-1 gene and protein in human granulosa cells.

Previous studies in animal models indicated an autocrine/paracrine action of endothelin-1 (ET-1) in the ovary. We now report evidence on the presence of ET-1 in human ovary during reproductive life. Immunohistochemical and in situ hybridization studies demonstrated a positive signal into cytoplasm of granulosa cells (GC) of follicles at different growth stages. The concentration of ET-1-like immunoreactivity (ET-1-LI) was also measured by a specific RIA in human follicular fluid (FF). FF samples were obtained from women in an in vitro fertilization program undergoing gonadotropin stimulation (group A; n = 24) or no treatment (group B; n = 7). The mean (+/-SD) ET-1-LI FF level in group A (4.85 +/- 2.06 pg/mL) was significantly higher than that in group B (1.29 +/- 0.43 pg/mL; P < 0.01), whereas the corresponding mean plasma levels were not significantly different and were not correlated to respective FF values. Our results indicate for the first time the presence of ET-1 and its messenger ribonucleic acid in the GC of the human ovary. The higher ET-1-LI levels found in the FF from women undergoing gonadotropin treatment suggest a modulation by gonadotropins and/or ovarian steroids of ET-1 production by GC.

Adult↗
PubMed1996

Sex steroid modulation of AT2 receptors in human myometrium.

In contrast to the abundant expression of the AT2 subtype of angiotensin II (AII) receptors during fetal development, AT2 receptor in adult life is expressed in few tissues. We now report studies on the presence and hormonal regulation of AT2 receptor in human pregnant and nonpregnant myometrium obtained from a large study population (n = 50). AT2 receptor subtypes have been characterized using self- and cross-competition curves among [125I]CGP42112A (a selective AT2 ligand), [125I](Sar1,Ile8)AII (a unselective antagonist), the corresponding unlabeled ligands, and several peptidic and nonpeptidic analogs with different affinities for the AT1 and AT2 receptor subtypes. We found that the human nonpregnant uterus expresses almost exclusively the AT2 subtype, and that [125I]CGP42112A is a selective probe to study human AT2 receptor. By using [125I]CGP42112A, we demonstrated that the density of AT2 receptor in human myometrium is dramatically affected by the hormonal milieu. Indeed, in the estrogen-dominant uterus of normal cycling women in the proliferative phase and that of perimenopausal women with anovulatory cycles, the density of binding sites was very high [1565 +/- 246 fmol/mg protein (n = 11) and 2176 +/- 429 (n = 7), respectively]. The concomitant presence of progestogens blunted the estrogen effect [term pregnancy, 61 +/- 12 fmol/mg protein (n = 5); secretive phase of the cycle, 453 +/- 154 (n = 10); combined oral contraceptive, 243 +/- 74 fmol/mg protein (n = 6)]. Very low concentrations of binding sites are also present in the sex steroid-deprived uterus of postmenopausal women (100 +/- 12 fmol/mg protein; n = 8) and the uterus of fertile women chronically treated with GnRH agonists (199 +/- 100 fmol/mg protein; n = 3). Hence, these data confirm the presence of AT2 receptors in human uterus and indicate their regulation by sex steroids.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1996

The presence of arterial anatomical variations can affect the results of duplex sonographic evaluation of penile vessels in impotent patients.

PURPOSE: Since penile arterial communications are present in a significant percentage of impotent patients, we evaluated whether peak systolic cavernous blood velocity after intracavernous prostaglandin E1 injection might be different in patients with and without arterial variants. MATERIALS AND METHODS: Cavernous blood flow was assessed with echo color Doppler ultrasound before and after intracavernous injection of prostaglandin E1 in 63 impotent patients. The penile shaft was accurately evaluated to detect arterial anatomical variants. Clinical erectile response was assessed by visual inspection and palpation. RESULTS: Of 23 patients who obtained a full erection with full rigidity after prostaglandin E1 injection the cavernous peak blood velocities in 11 with penile arterial communications were significantly less than those in 12 without arterial communications. CONCLUSIONS: The generally accepted limit of normal for cavernous peak blood flow obtained after prostaglandin E1 injection (greater than 25 to 30 cm. per second) must be interpreted carefully because lower peak blood velocities may be found in subjects with a full erectile response if arterial communications are present.

Alprostadil↗
PubMed1995

Tyrosine kinase inhibition reduces the plateau phase of the calcium increase in response to progesterone in human sperm.

Progesterone (P) has previously been shown to induce a rapid increase in [Ca2+]i as well as tyrosine phosphorylation of proteins in human spermatozoa. Both these effects are essential for induction of the acrosome reaction by P. We investigated a possible relationship between the P-induced calcium increase and tyrosine kinase activation, by evaluating the effect of the tyrosine kinase inhibitor genistein on these two effects. We found that preincubation with genistein abolished P-induced tyrosine phosphorylation of two sperm proteins of 97 and 75 kDa molecular weight and significantly inhibited the plateau phase of P-induced [Ca2+]i increase without affecting the peak phase. Conversely, the plateau phase was enhanced by the tyrosine phosphatase inhibitor Na3VO4. The effect of genistein was specific for P, since no inhibition was observed on the [Ca2+]i increase induced by thapsigargin, an inhibitor of endoplasmic Ca(2+)-ATPase previously shown to mobilize Ca2+ in spermatozoa. These results indicate that tyrosine kinase activation is involved in the generation of the plateau phase of Ca2+ influx induced by P, and suggest the possibility that two different pathways are involved in the induction of Ca2+ entry by P in human sperm.

Biological Transport↗
PubMed1995

Stimulation of protein tyrosine phosphorylation by platelet-activating factor and progesterone in human spermatozoa.

Tyrosine phosphorylation of proteins is involved in several sperm functions, including capacitation, motility, and acrosome reaction of spermatozoa. This study was undertaken to determine changes of tyrosine phosphorylation during 'in vitro' capacitation as well as the ability of platelet-activating factor (PAF) and progesterone (P), two known activators of sperm functions, to stimulate tyrosine phosphorylation of human sperm proteins. Spermatozoa were capacitated in BSA-containing medium and incubated with PAF (10-1000 nM) and progesterone (0.1-1 microgram/ml). After SDS-PAGE, sperm proteins were transferred to nitrocellulose and tyrosine phosphorylated proteins immunodetected by reacting with anti-phosphotyrosine antibody. The antibody mainly reacted with two proteins of approximately 97 and 75 kDa. The level of phosphorylation increased in these two proteins as a function of capacitation time, with a maximum between 120 and 180 min. In addition, phosphorylation in these two proteins was increased in capacitated spermatozoa by treatment with progesterone and PAF and was greatly reduced by pre-incubation with the tryosine kinase inhibitor erbstatin. Furthermore, pre-incubation with the two tyrosine kinase inhibitors erbstatin and genistein inhibited the induction of acrosome reaction by progesterone and, partially, by PAF. Our results suggest a role for tyrosine kinase(s) in the mechanism of capacitation and activation of human spermatozoa by PAF and progesterone.

Acrosome↗
PubMed1995

Actions of progesterone on human sperm: a model of non-genomic effects of steroids.

Non-genomic actions of steroids have been extensively studied in the last few years. Among these actions, the non-genomic effect of progesterone (P) on human spermatozoa appears to be very promising, in view of the dramatic effect of this steroid on intracellular calcium, activation of tyrosine kinase, and induction of acrosome reaction. We have shown that the ability of spermatozoa to respond to P increases during the process of capacitation and is not counteracted by the P-receptor antagonist RU486 nor by the GABAA antagonists bicuculline and picrotoxin. We have also shown that P increases tyrosine phosphorylation of a sperm protein of about 97 kDa, suggesting activation of tyrosine kinase(s). In addition, we found that P induces a perturbation of sperm membrane phospholipid metabolism resulting in an increase of synthesis of platelet-activating factor and liberation of arachidonic acid. Results of these biochemical studies indicate that P is able to stimulate several signal transduction pathways in human sperm. We have also investigated responsiveness to P in sperm of oligozoospermic subjects as well as of men undergoing an in vitro fertilization (IVF) program. Our results show that the percentage increases of intracellular calcium and acrosome reaction in response to P is significantly reduced in oligozoospermic men as well as in subjects with reduced fertilization rate. Moreover, in the latter subjects response to P is highly significant correlated to fertilization rate of oocytes. These studies indicate that a biochemical alteration of sperm in their capacity to respond to P might be responsible for reduced fertilizing ability.

Acrosome↗
PubMed1995

Intracellular calcium increase and acrosome reaction in response to progesterone in human spermatozoa are correlated with in-vitro fertilization.

In this study we have investigated responsiveness to progesterone in spermatozoa from a group of unselected male partners of couples undergoing in-vitro fertilization (IVF). We evaluated progesterone-stimulated intracellular Ca2+ ([Ca2+]i) and percentage increase in acrosome reaction in the same sperm sample used for oocyte inseminations. [Ca2+]i was measured with a fluorimetric method, while the acrosome reaction was assessed using a fluorescent probe (fluorescein isothiocyanate-labelled peanut lectin). The average percentage [Ca2+]i as well as the rate of increase in the frequency of acrosome reaction following progesterone challenge were significantly lower (P < 0.005) in the group of patients with a fertilization rate < 50%. In addition, significant correlations between the fertilization rate and the progesterone-stimulated [Ca2+]i and acrosome reaction increases (r = 0.78 and r = 0.79 respectively) were observed. Furthermore, in cases of fertilization failure, no increase of [Ca2+]i or acrosome reaction was observed in response to progesterone with the exception of one case. Our results indicate that [Ca2+]i and acrosome reaction increases in response to progesterone can be of value in the prediction of sperm fertilizing ability. As the two parameters were significantly correlated to each other (r = 0.86), the two assays have similar IVF predictive value and might be used interchangeably as a diagnostic tool in the assignment of male patients to the different kinds of assisted fertilization techniques.

Acrosome↗
PubMed1995

In-vivo studies on ovarian insulin-like growth factor I concentrations in human preovulatory follicles and human ovarian circulation.

In some recent hypotheses, the ovary has been indicated as a source of insulin-like growth factor (IGF)-I, with synthesis regulated from local steroidal and non-steroidal substances. We measured IGF-I concentrations in both serum and follicular fluid of women undergoing in-vitro fertilization (IVF) and embryo transfer, in both induced and spontaneous cycles. It was found that serum and follicular IGF-I concentrations were correlated with follicular morphology, oocyte maturity, steroid concentrations and clinical characteristics of IVF cycles. In addition, we measured IGF-I concentrations in both peripheral and ovarian circulation to gain further detailed information on the contribution of the ovary to IGF-I production. The results of our study support the hypothesis that follicular IGF-I is probably derived by diffusion from peripheral circulation and that local production appears unlikely.

Adult↗
PubMed1995

Alfa-inhibin and transferrin in human fetal testis.

Aim of this research was to investigate the immunohistochemical localization of alfa-inhibin and transferrin in the human fetal testis. In addition, an attempt was made to identify the Sertoli cells in primary cell cultures of fetal testes by the demonstration of the mRNA for transferrin and the presence of the FSH receptor. 15 fetal testes (8-12 weeks) were utilized. The results of this study show: 1. In sections, immunoreactivity for alfa-inhibin was present in the interstitial cells, whereas transferrin was localized in Sertoli cells; 2. After 20 days of primary culture: a) the percentage of immunoreactive cells for both the substances was about 15%; b) the presence of FSH receptor and the expression of transferrin mRNA were observed in 12-15% of cells. These findings suggest: 1. alfa-inhibin and transferrin are present in the human fetal testis; 2. the expression of transferrin mRNA and the presence of the FSH receptor permit the identification of the Sertoli cells in primary cultures of fetal testes (8-12 weeks).

Cells, Cultured↗
PubMed1994

Platelet-activating factor mediates an autocrine proliferative loop in the endometrial adenocarcinoma cell line HEC-1A.

We investigated the synthesis and biological effects of platelet-activating factor (PAF) in the human endometrial cancer cell line HEC-1A. We found that HEC-1A cells actively synthesize and release PAF, as demonstrated by both [3H]acetate incorporation into PAF and gas chromatography-mass spectrometry studies. HEC-1A cells not only synthesize but also respond to PAF. Indeed, in fura-2-loaded cells, PAF stimulates [Ca2+]i increase with a median effective concentration of 5.6 nM. Furthermore, PAF induces a time-dependent expression increase of the nuclear protooncogene c-fos with a median effective concentration of 130 nM and stimulates DNA synthesis (median effective concentration, 700 nM). All of these effects are inhibited by the PAF receptor antagonist L659,989. Radioligand binding studies indicated the presence of two populations of PAF receptors with affinity constants in the nanomolar and micromolar range. Since the PAF antagonist per se inhibits DNA synthesis and cell proliferation, we suggest that PAF supports an autocrine growth circuit in HEC-1A cells. On the contrary, in the uterine leiomyosarcoma cell line SK-UT-1, which does not express specific binding sites for PAF, neither this phospholipid nor its receptor antagonist affect DNA synthesis. Our results provide evidence for the existence of an autocrine proliferative loop involving PAF in the endometrial cancer cell line HEC-1A.

Acetyl-CoA C-Acetyltransferase↗
PubMed1994

The duration of prolactin secretory bursts from the pituitary is independent from both prolactin and gonadal steroid plasma levels in women and in men.

The intrinsic secretory characteristics of prolactin (PRL) have been investigated using newly developed algorhythms for instantaneous secretory rate (ISR) computation. PRL secretory rate, its intrinsic pulsatile characteristics and their possible dependance from gonadal steroids were investigated in five groups of subjects: a) 11 women during the follicular and luteal phase of the same menstrual cycle; b) 5 healthy postmenopausal women; c) 6 women affected by functional hyperprolactinemia; d) 5 normal men; e) 4 agonadal subjects before and during testosterone replacement therapy. All subjects underwent a 6 hours pulsatility study, from 08:00 to 14:00, sampling every 10 minutes. PRL plasma concentrations were determined using a RIA system and the presence of PRL secretory pulses was evaluated with program DETECT, both on plasma time series and after ISR computation. A distinct PRL episodic release was observed in all groups (follicular phase: 5.5 +/- 0.5, luteal phase: 6.5 +/- 0.6, postmenopause: 5 +/- 1, hyperprolactinemic women: 4.2 +/- 0.8, men: 4.8 +/- 0.4, agonadal before testosterone: 6 +/- 1, agonadal during testosterone administration: 5.3 +/- 0.3 peaks/6h), but mainly the computation of ISR allowed to demonstrate that the duration of the lactotropes secretory events was constant in all groups studied. PRL secretory bursts duration ranged between 23.1 +/- 1.8 and 25.4 +/- 2.5 minutes independently both on PRL or on sex steroid plasma levels. In conclusion, the present report shows that in different physiological conditions the intrinsic secretory bursts from lactotropes are constant in duration independently from the functional state, sex and the steroid hormone levels.

Adult↗
PubMed1994

Platelet-activating factor in human endometrium.

Platelet-activating factor (PAF) is a phospholipid actively produced by human endometrium and deeply involved in the processes of ovoimplantation and labor. We recently found that PAF represents a new autocrine growth factor for a human adenocarcinoma cell line, HEC-1A. Indeed, biologically active PAF is synthesized by HEC-1A cells, under progesterone control. In HEC-1A cells, PAF regulates intracellular calcium concentration ([Ca2+]), DNA synthesis and expression of early oncogenes. All these effects are blocked by the receptor antagonist L659,989. However, while nanomolar concentrations of PAF mobilize [Ca2+], only micromolar concentrations affect cell growth, suggesting heterogeneity of PAF receptors or signaling. Two distinct populations of PAF receptors are present in HEC-1A cells, which bind PAF in nanomolar and micromolar concentrations, respectively. Since HEC-1A cells are producing elevated concentrations of PAF and micromolar concentrations of the PAF antagonist L659,989 inhibit cell proliferation, an autocrine role for PAF is suggested in HEC-1A cells.

Adenocarcinoma↗
PubMed1994

Effect of platelet-activating factor on motility and acrosome reaction of human spermatozoa.

The effect of platelet-activating factor (PAF) on motility parameters and induction of the acrosome reaction in human spermatozoa was investigated in 36 unselected men with different degrees of initial sperm motility. The characteristics of sperm movement were assessed by computer-assisted sperm analysis (Hamilton-Thorn Motility Analyser) and the percentage of acrosome-reacted spermatozoa was evaluated after 1 h incubation with PAF (10 nM) and staining with fluorescent peanut lectin. We found that short-term (4 h max) incubation with PAF significantly enhanced total and progressive sperm motility as well as acrosome reaction. An increase of sperm motility in response to PAF was present in 16 out of the 25 subjects studied (defined as responders) and was inversely correlated with basal motility. In the 11 samples (six responders and five non-responders) where the incubation with PAF was prolonged overnight, an increase of sperm motility was present in all the subjects studied. Similarly, an increase in numbers of acrosome reactions in response to 10 nM PAF was present in 20 out of the 26 subjects examined, and was inhibited by the PAF receptor antagonist L659 989. Our results indicate a possible physiological role for PAF in fertilization and suggest a potential use of PAF in in-vitro fertilization techniques in cases of reduced sperm motility.

Acrosome↗
PubMed1994

Simultaneous measurement of sperm LDH, LDH-X, CPK activities and ATP content in normospermic and oligozoospermic men.

Total lactate dehydrogenase (LDH), LDH-X, creatine phosphokinase (CPK) activities and ATP content were measured in washed spermatozoa from 188 normospermic and 94 oligozoospermic men. These four biochemical parameters were significantly higher (p < 0.001) in spermatozoa from oligozoospermic men than in those from normospermic men and were related inversely to sperm concentration. In oligozoospermic men the activity of sperm LDH and LDH-X was related significantly to sperm CPK activity (r = 0.5486 and r = 0.4442, respectively), whereas this relationship was less evident in normospermic men (r = 0.4124 and r = 0.3844, respectively). Sperm ATP content was related weakly to sperm LDH, LDH-X and CPK activities both in oligozoospermic and normospermic men. After separation on a discontinuous (40% and 80%) Percoll gradient LDH, LDH-X, CPK activities and ATP content in 80% separated sperm fractions from 48 normospermic and 30 oligozoospermic men were found to be significantly lower than in the initial semen sample in both groups of subjects. The 80% separated sperm fractions from oligozoospermic and normospermic men did not differ in their LDH or LDH-X activities or ATP content, whereas sperm CPK activity was still significantly higher in oligozoospermic men. These data suggest that, of the four parameters studied, high levels of intracellular CPK activity are the most relevant biochemical feature of spermatozoa from oligozoospermic men.

Adenosine Triphosphate↗
PubMed1993

Stimulation of platelet-activating factor synthesis by progesterone and A23187 in human spermatozoa.

The presence of platelet-activating factor (PAF) has been demonstrated recently in mammalian spermatozoa, together with evidence for a role of this phospholipid in enhancing sperm motility and fertilizing ability. To investigate whether PAF synthesis and release occurs in human spermatozoa following incubation with stimuli that induce acrosome reaction, spermatozoa were incubated with progesterone and A23187, two known inducers of the exocytotic event. PAF synthesis (remodelling pathway) was assessed by [3H]acetate incorporation into PAF. Treatment of spermatozoa with progesterone and A23187 resulted in an increase of [3H]acetate incorporation into PAF. Most of the newly synthesized [3H]PAF formed in response to acrosome reaction was found in the supernatant, suggesting a release of the phospholipid from spermatozoa. PAF-like material extracted from human spermatozoa was able to induce aggregation of rabbit platelets and showed identical retention time and the same ion m/e values as authentic PAF when analysed with g.c.-m.s. Lyso-PAF:acetyl-CoA acetyltransferase (EC 2.3.1.67) activity in human spermatozoa was also studied and showed similar kinetic parameters to those described for other cell systems. Stimulation of spermatozoa with progesterone and A23187 induced an increase of [3H]arachidonic acid release, suggesting an activation of phospholipase A. In conclusion, our results demonstrated increased production and release of PAF in human sperm following stimulation with progesterone and A23187 and suggest a role for this phospholipid in the activation of spermatozoa.

Acetyltransferases↗
PubMed1993

Estrogenic suppression by different administration schedules of goserelin depot for treatment of endometriosis.

Eighteen patients affected by laparoscopically confirmed endometriosis were randomly assigned to three different schedules of treatment with gonadotropin-releasing hormone agonist (GnRH-a) (goserelin depot formulation 3.6 mg) every 28 days for 6 months. Six women received the first implant in early follicular phase, 4 in late luteal phase and 8 in 3rd and 17th day from onset of menses. Pretreatment and posttreatment laparoscopic score, performed according to the American Fertility Society scoring system, were compared; a significant reduction in the extent of disease was observed in each group investigated (A and C: p < 0.01; B: p < 0.05). In each treatment group after the second GnRH-a implant the mean levels of estrone-3-glucuronide (E1-3G), daily measured in early morning urine specimens during the control cycle and the first three months of therapy, were suppressed to menopausal women range. In group B during the 2nd and 3rd month of therapy, the urinary mean levels of E1-3G were significantly lower than in group A and C. In conclusion the different goserelin depot administration schedules gave similar laparoscopic improvement, in spite of the first GnRH-a administration in luteal phase allowed a more marked estrogenic suppression.

Adult↗