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M Maggi

Publications and source records attributed to M Maggi.

At least 73 records · Page 4Linked to original sources
PubMed1996

Down-regulation of substance P receptors during colitis induced by trinitrobenzene sulfonic acid in rats.

Neurochemical and functional studies were performed to investigate the role of substance P (SP) during trinitrobenzene sulfonic acid (TNB)-induced colitis. Time course studies showed that tissutal SP-like immunoreactivity levels decreased in acute or chronic phases of the experimental colitis. The affinity of SP was not significantly reduced up to 1 week after TNB-induced colitis but a decreased density of SP binding sites was observed at all times. The subcutaneous administration of neurokinin (NK)1 receptor antagonist RP 67580 (0.1-1 mumol/kg daily x 1 week) did not affect the injury induced by the hapten. These findings suggest that changes in SP seem to be the effect rather than the cause of colitis and differ from those observed in human inflammatory bowel diseases.

Animals↗
PubMed1996

Endothelin 1 is overexpressed in human cirrhotic liver and exerts multiple effects on activated hepatic stellate cells.

BACKGROUND & AIMS: Endothelin (ET) 1 could be involved in the regulation of hepatic microcirculation and in the development of portal hypertension. The expression and distribution of ET-1 in normal and cirrhotic liver tissue and its effects on hepatic stellate cells (HSCs), liver-specific pericytes, were investigated. METHODS: ET-1 expression in liver tissue was analyzed using in situ hybridization and immunohistochemistry. Secretion of ET-1 by HSC was evaluated by radioimmunoassay. Changes in intracellular Ca2+ concentration and cell contraction were studied using digital video imaging. Specific binding of ET-1 was evaluated using self- and cross-displacement curves. RESULTS: ET-1 expression was markedly enhanced in cirrhotic liver tissue, where activated HSCs were shown to be major sites of ET-1 synthesis, as confirmed by studies performed on cultured human HSC. ET-1 exerted several biological actions on HSC, including mitogenicity, activation of mitogen-activated protein kinase, and a rapid increase in intracellular Ca2+ coupled with reversible cell contraction. All these effects appeared to be mediated by ETA receptors. Finally, the relative prevalence of ETA and ETB binding sites changed with the progressive phenotypical modulation of HSC. CONCLUSIONS: ET-1 may act as a paracrine and autocrine factor for activated HSC and contribute to the increased resistance to portal flow in cirrhotic liver.

Adipocytes↗
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

1 alpha, 25-dihydroxy-16-ene-23-yne-26,27-hexafluorocholecalciferol (Ro24-5531) modulation of insulin-like growth factor-binding protein-3 and induction of differentiation and growth arrest in a human osteosarcoma cell line.

1 alpha,25-Dihydroxycholecalciferol [1,25-(OH)2D3] is a potent differentiating agent in a variety of tumor cell lines. However, the induction of severe hypercalcemia has limited its clinical use. Several analogs have been synthesized that retain the antiproliferative differentiating effects of 1,25-(OH)2D3, but do not have the calcitropic effect of the parent compound. One such analog, 1 alpha,25(OH)2-16-ene-23-yne-26,27-hexafluorocholecalciferol (Ro24-5531), can induce differentiation in HL-60 cells and does not induce hypercalcemia in animal models. We, therefore, evaluated the effect of Ro24-5531 on a human osteosarcoma cell line, MG-63. Compared with 1,25-(OH)2D3, the analog Ro24-5531 is 10-100 times more potent as an inhibitor of MG-63 cell proliferation, as determined by [3H]thymidine incorporation and/or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The inhibition in cell growth is accompanied by a decrease in the expression of p34cdc2 (> 4-fold), a protein critically involved in cell cycle regulation. Ro24-5531 treatment of MG-63, at a concentration of 10(-8) mol/L, induced expression of the bone differentiation markers biglycan and osteocalcin, as determined by Northern analysis. These data suggest that Ro24-5531 treatment induces growth arrest coupled with differentiation. To begin to evaluate the mechanisms by which Ro24-5531 may exert an effect, we evaluated the effect of Ro24-5531 on components of the insulin-like growth factor I (IGF-I) signaling pathway, an important regulator of normal bone growth and differentiation. The expression of IGF-binding protein (IGFBP), IGFBP-3 messenger ribonucleic acid, and protein levels are increased 20-fold after 72 h of treatment with Ro24-5531 and are associated with a marked increase in detectable binding of ligand to binding protein, as measured by RRA. These data suggest an association between Ro24-5531-induced growth arrest and increased expression of IGFBP-3.

Bone Development↗
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

Influence of oestrogens on muscarinic receptor density and contractile response in the guinea-pig uterus.

The objective of this study was to investigate the contractile response in vitro of uterine and myometrial strips from control and oestrogen-treated guinea-pigs to carbachol. In addition, the muscarinic receptor parameters in subcellular preparations from the myometrium of the same animals were evaluated. Strips of guinea-pig uterus contract in response to carbachol in a concentration dependent manner and the effect of carbachol is independent of the presence of an intact endometrium. However, treatment with oestrogen reduces the response to carbachol, when expressed with respect to the effect of KCl. Measurement of the specific binding of [3H]quinuclidinyl benzylate ([3H]QNB) to myometrial membranes from control and oestradiol-treated immature guinea-pigs showed that oestradiol significantly decreased the number of specific binding sites of [3H]QNB, but did not change the apparent affinity of specific [3H]QNB binding. Moreover, the apparent affinity constants for the different antagonists showed a close similarity to those obtained at muscarinic receptors present in the myometrium from control and oestradiol-treated guinea-pigs.

Animals↗
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↗
PubMed1996

Quantitation of somatostatin receptor type 2 gene expression in neuroblastoma cell lines and primary tumors using competitive reverse transcription-polymerase chain reaction.

We previously reported the presence of somatostatin (SS-14)-binding sites in a wide panel of human neuroblastoma (NB) tumor cell lines. Given that the adrenal gland and its relative embryonal and adult tumors express an abundance of mRNA for somatostatin receptor type 2 (sst2) mRNA, we studied the quantitative expression of sst2 in 6 NB cell lines and 15 primary tumors using competitive reverse transcription (RT)-PCR. This method uses an insertion mutant of the target gene as a competitor for the RT-PCR reaction, thus allowing exact quantitation of sst2 mRNA abundance. We found expression of specific transcripts for sst2 in all of the NB cell lines and tumors investigated (range, 9 x 10(5)-4 x 10(9) molecules/microg RNA). In NB cells, the expression of sst2 was highly correlated with SS-14-binding sites (R = 0.93). In primary tumors, sst2 was positively related to the expression of the neuroendocrine marker secretogranin II (P < 0.05) and negatively related to N-myc amplification (a poor prognostic factor, P < 0.005) and metastatic dissemination (P < 0.05). In addition, Kaplan-Meier curves indicate that sst2 expression is positively related to survival (P = 0.01). In a patient with stage IVs disease (a spontaneously regressing form), we found the highest sst2 expression (4 x 10(9) molecules/microgram RNA), a value relatively similar to that of normal adrenal. In conclusion, these data indicate that quantitation of sst2, as assessed with competitive RT-PCR, could represent a new prognostic tool in the neuroendocrine tumor NB. Since sst2 recognizes octreotide with high affinity, these findings could also have both diagnostic and therapeutic value.

Adult↗
PubMed1995

Identification and characterization of functional angiotensin II receptors in human neuroblastoma cells.

The presence of specific AII receptors in 6 different human neuroblastoma cell lines was investigated using binding, cAMP and [Ca2+]i studies. We found high affinity (0.1 nM), low capacity ((1-2).10(3) sites/cell) binding sites for [125I](Sar-1,Ile-8)AII in one half of the cell lines studied. In the positive cell lines mathematical modeling of multiple competition curves among AII and analogs strongly indicated the presence of a homogenous class of sites, i.e., AT1 receptors. The presence of AT1 receptors was further substantiated by AII-induced inhibition of VIP-stimulated cAMP levels and by AII-evoked [Ca2+]i transient. The density of AT1 receptors in neuroblastoma cells was not affected by treatment with pertussis toxin and retinoic acid but was significantly increased by subacute treatment with VIP. In neuroblastoma cells, AII does not stimulate DNA synthesis, suggesting other roles rather than mitogenesis. Neuroblastoma cells represents an interesting model to investigate the function of AII in neural crest derived tissues.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1995

Identification and localization of endothelin-1 and its receptors in human fetal jaws.

In the mouse, disruption of the endothelin-1 (ET-1) gene causes severe craniofacial deformities, including mandibular hypoplasia. Since the phenotype of ET-1-deficient mice shows features in common with inherited human mandibulofacial dysostosis, we investigated the presence of ET-1 and its receptors in human fetal craniofacial tissues of 9- to 12-week-old fetuses. We found that ET-1 is immunolocalized in the epithelial cells of the oral cavity. Radioligand binding studies indicate the presence of elevated concentrations of both ETA and ETB receptors in membranes derived from fetal jaws. Using autoradiography, 125I-ET-1 binding sites were shown to be localized within the embryonic mandibular process of the oral cavity, where they were confined to the mesenchymal-derived osteogenic cells. Our data suggest a role for ET-1 in the development of the human mandible.

Abnormalities, Multiple↗
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

Receptor-mediated uterine effects of vasopressin and oxytocin in nonpregnant women.

OBJECTIVE: To study in nonpregnant women myometrial actions of vasopressin and oxytocin and the involvement in these effects of specific uterine receptors. SUBJECTS: Twenty-eight women undergoing hysterectomy for benign gynaecological disorders. INTERVENTIONS: Intrauterine pressure recordings. Intravenous bolus injections of 10 pmol/kg body weight of vasopressin and oxytocin. Repeated blood sampling for measurement of vasopressin and oxytocin concentrations in plasma. Recording of effects of vasopressin and oxytocin on isolated myometrium. Estimation of myometrial concentrations of vasopressin V1a and oxytocin receptors. Measurement of plasma oestradiol and progesterone. MAIN OUTCOME MEASURES: Vasopressin- and oxytocin-induced increases of the area under the in vivo recording curve over 10 minutes and EC50 concentrations of dose-responses in vitro. Concentrations of vasopressin V1a and oxytocin receptors. RESULTS: Vasopressin was on average four times more potent than oxytocin in vivo. The effect of vasopressin premenstrually was more pronounced than in women under oestrogen influence only (proliferative phase-hyperproliferation; P = 0.02), and tended to be more marked than in those in the luteal phase (P = 0.07). No significant variation in oxytocin response with the hormonal state was observed. EC50 concentrations of vasopressin were more than 20 times lower than those of oxytocin. The median concentration of the vasopressin V1a receptor was 208 (range 139-343) fmol/mg protein and that of the oxytocin receptor 49 (38-87) fmol/mg protein. Vasopressin receptor concentrations and in vivo effects of this peptide did not correlate, whereas for those of oxytocin a significant correlation was observed (P = 0.02). CONCLUSION: The high potency of vasopressin in nonpregnant women, particularly premenstrually, firmly supports an aetiological importance of this peptide in the uterine hyperactivity of primary dysmenorrhoea. Oxytocin seems to be less important in this condition in view of its much smaller potency and the absence of increase in effect premenstrually. Vasopressin appears to influence both the oxytocin and the vasopressin V1a receptor sites in the uterus, whereas oxytocin acts specifically on its own receptor.

Adult↗
PubMed1995

Potential use of oxytocin and vasopressin V1a antagonists in the treatment of preterm labour and primary dysmenorrhoea.

In order to study the involvement of oxytocin (OT) and vasopressin (AVP) in mechanisms of uterine activation and to clarify the therapeutic potential of antagonists to these hormones in preterm labour and primary dysmenorrhoea, studies of human uterine contractility in vivo and in vitro as well as measurements of OT and AVP V1a receptors were performed. Good correlations between OT receptor concentrations and effects on contractility were observed in both the pregnant and non-pregnant states, which indicates that OT acts specifically on its own receptor in the uterus. For AVP there was lack of such correlation which may suggest that this hormone influences both the OT and AVP V1a receptor sites. At the onset of labour both preterm and at term no marked increase in the OT receptor concentration was observed, but OT may still be involved in the initiation of labour, being produced locally in the uterus and not detectable in plasma. We observed a reduced OT receptor concentration in advanced labour and after OT infusion, which suggests that OT influences its own receptor. The AVP V1a receptor concentration and the effect of AVP on the uterus were about equal to those for OT, and the concentration of AVP V1a receptors also tended to decrease in advanced labour, observations which support an involvement also of AVP in the mechanisms of labour. In non-pregnant women AVP receptors as well as uterine effects of AVP in vitro and in vivo were about five times higher than those for OT, and the effect of AVP was increased premenstrually. This firmly supports an aetiological role of this peptide in the uterine hyperactivity of primary dysmenorrhoea. We have also shown that the analogue 1-deamino-2-D-Tyr-(OEt)-4-Thr-8-Orn-OT, which blocks both the OT and AVP V1a receptor sites, given by intravenous infusion inhibits both preterm labour and dysmenorrhoea, and this is in agreement with our receptor and contractility findings.

Arginine Vasopressin↗
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

Identification, characterization, and biological activity of somatostatin receptors in human neuroblastoma cell lines.

To investigate the presence of biologically active somatostatin (SS) receptors in neural crest-derived tumors, radioligand binding studies, cyclic AMP accumulation, intracellular calcium, and growth assays were performed in eight human neuroblastoma (NB) cell lines. Mathematical modeling of binding experiments strongly indicates the presence of heterogeneity of sites. The first site (SSR1) is present in 40% of the NB cell lines and binds with low capacity (0.5 pmol/mg protein) and high affinity (0.1-1 nM) SS14, SS28, and analogues. The second site (SSR2) is a high capacity site (200 pmol/mg protein), widely distributed in all of the cell lines investigated, that shows relative selectivity yet low affinity (100 nM) for SS14, SS28, and [D-Trp8]SS14 without any apparent biological activity. SSR1 is coupled to a pertussis toxin-sensitive G protein, inhibits forskolin- or VIP-stimulated adenylate cyclase activity, decreases intracellular free calcium, and mediates inhibition (30%) of both DNA synthesis and cell growth. Analysis of cell cycle distribution in aphidicolin-synchronized SSR1-positive NB cells indicated that this inhibitory effect is partially mediated by a transient accumulation in G0-G1. Our data indicate high affinity binding sites for SS14, and analogues are present and biologically active in a subset of NB cells.

Binding Sites↗