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A Filippini

Publications and source records attributed to A Filippini.

At least 37 records · Page 2Linked to original sources
PubMed1997

Dual control of seminiferous tubule contractility mediated by ETA and ETB endothelin receptor subtypes.

Testicular myoid cells surrounding the seminiferous tubule are contractile cells responsible for peritubular contractility and for the propulsion of tubular fluid and spermatozoa. We have investigated the contractile response of rat myoid cells to endothelins (ETs) in cell and organ culture and analyzed the cell signaling involved. ET-2, ET-3, and IRL 1620, a highly selective agonist of ETB receptor, elicit [Ca2+]i increases, though with dissimilar potencies and kinetics. Competition binding assays using [125I]ET-1, [125I]ET-3 and [125I]IRL 1620 show that myoid cells express both ETA and ETB receptors with high affinity for ET-1 and ET-1/ ET-3, respectively. All endothelin isoforms activate phosphoinositide (PI) turnover, but only stimulation of the ETA receptor mediates both PI turnover and mobilization of [Ca2+]i. Although stimulation of the ETB receptor with IRL 1620 fails to produce a significant effect on inositol phosphate (IP) production, it induces mobilization of a thapsigargin-sensitive intracellular Ca2+ pool in the absence of any measurable IP production. We also studied the effect of U-73122 [1-(6-[17-beta-3-methoxyestra-1,3,5 (10)-trien-17-yl] amino/hexyl)-1H-pirrole-2,5-dione] and its inactive analog, U-73343, on Ca2+ mobilization and IP production after selective stimulation of ET receptors. U-73122 (1 microM) completely inhibited the effect of ETA-mediated ET-1 stimulation of IP production, whereas U-73343 was inactive. However, in the presence of U-73122, the selective stimulation of ETB receptors induced the mobilization of a thapsigargin-sensitive and inositol phosphate-independent intracellular Ca2+ pool. The ETB receptor-dependent mobilization of [Ca2+]i resulted mainly from Ca2+ release from intracellular Ca2+ stores. This paper illustrates contraction of myoid cells in the seminiferous tubule in response to selective activation of either ET receptor. Scanning electron microscopy of the peritubular tissue demonstrates that the contractile response to ET was inhibited by a combination of BQ-123 and BQ-788, but not by either antagonist alone. Moreover, the observation that selective stimulation of ETB receptor with IRL 1620 also resulted in cell contraction strongly suggests that stimulation of either ETA or ETB receptors alone may be sufficient to elicit seminiferous tubule contractility. Two types of receptors account for the actions of endothelin on contractile activity of seminiferous tubule: 1) an ETA receptor that is positively coupled to phospholipase C (PLC) and Ca2+ mobilization; and 2) an ETB receptor that induces the mobilization of a thapsigargin-sensitive intracellular Ca2+ pool in a manner independent of the formation of inositol phosphates. ET may play a complex role in regulating the flux of spermatozoa along the seminiferous tubule through its contractile effect on peritubular myoid cells.

Animals↗
PubMed1996

Identification and characterization of an ecto-ATPase activity in rat Sertoli cells.

A membrane associated extracellular ATPase (ecto) has been identified on rat Sertoli cells. Sertoli cell ecto-ATPase demonstrated a Km for ATP of 114 muM and a V(max) of 1.79 mumol/min/2 x 10(5) cells and was activated by either Mg2+ or Ca2+. This ecto-ATPase hydrolyzes other nucleoside triphosphates, but is inactive with ADP. The effects of some possible inhibitors of ectonucleotidases on the breakdown of extracellular ATP by Sertoli cells were also investigated.

Adenosine Triphosphatases↗
PubMed1996

Direct visualization of rat peritubular myoid cell contraction in response to endothelin.

Seminiferous tubule contractility is fundamental for sperm progression towards the rete testis; hence its regulation represents a key point in male fertility. Endothelin-1 (ET-1), a potent stimulator of smooth muscle contractility, has recently been shown to be produced in the testis, as well as to bind to specific receptors on myoid cells and thereby activate intracellular signaling. The present paper illustrates contraction of isolated myoid cells in response to ET-1 both in phase-contrast and scanning electron microscopy. Moreover, a simple method is described that allows visualization of a dramatic endothelin-induced rearrangement of myoid cell actin filaments in whole-mount preparations of seminiferous tubules. The response, which can be observed within seconds from stimulation, was paralleled by cell shape changes that were well apparent in scanning electron microscopy. The present report provides the first direct evidence that endothelin is an agonist of myoid cell contractility. Moreover, the experimental approach described could represent a promising tool for the screening of potential agonists of peritubular contractility and for the analysis of their mechanisms of action. In this regard, preliminary evidence is presented on myoid cell contractile response to [Arg8]-vasopressin.

Actin Cytoskeleton↗
PubMed1995

Inflammatory mediators increase surface expression of integrin ligands, adhesion to lymphocytes, and secretion of interleukin 6 in mouse Sertoli cells.

The expression of the cell adhesion molecules ICAM-1, ICAM-2, and VCAM-1 and the secretion of the cytokine interleukin 6 have been measured in mouse Sertoli cells cultured in vitro. Cytometric analysis revealed that, in basal conditions, low levels of ICAM-1 and VCAM-1 were present on the surface of the cells, whereas treatment with interleukin 1, tumor necrosis factor alpha, lipopolysaccharide, or interferon gamma induced, with different kinetics, increases in their expression. ICAM-2 was not detectable in basal conditions, nor was it inducible. Electron microscopic analysis and binding experiments using 51Cr-labeled lymphocytes demonstrated that increased expression of ICAM-1 and VCAM-1 on the surface of Sertoli cells, induced by inflammatory mediators, determines an augmented adhesion between the two cell types. The same stimuli, with the exception of interferon gamma, produced a rapid and remarkable increment of interleukin 6 production by Sertoli cells. These results suggest the presence of both direct and paracrine mechanisms of interaction between Sertoli and immune-competent cells, possibly involved in the control of immune reactions in the testis. Such mechanisms are of interest for the understanding of autoimmune pathologies of the testis and, if confirmed in humans, they could be involved in the sexual transmission of human immunodeficiency virus infection.

Animals↗
PubMed1995

TNF-alpha induces surface modifications in mouse Sertoli cells: physiopathological implications.

The expression of the adhesion molecules ICAM-1 and VCAM-1 has been measured in mouse Sertoli cells cultured in vitro. Cytometric analysis revealed that, in basal conditions, low levels of ICAM-1 and VCAM-1 were present on the surface of the cells, whereas treatment with TNF-alpha induced an increase in their expression. Binding experiments using both 51Cr-labelled lymphocytes, for quantitative analysis, and scanning electron microscopy demonstrated that increased expression of ICAM-1 and VCAM-1 on the surface of Sertoli cells, induced by TNF-alpha, determines an augmented adhesion between the two cell types. These results suggest the presence of a specific mechanism of interaction between Sertoli and immune-competent cells, possibly involved in the control of the immune response in the testis following an inflammatory reaction in situ. Such mechanism is of interest for the understanding of auto-immune pathologies of the testis and, if confirmed in humans, it could be involved in the sexual transmission of HIV infection.

Animals↗
PubMed1994

Advances in rectal cancer surgery.

PURPOSE: We discuss our experience in radical rectal cancer surgery and critically review the results of the current literature. In particular, the importance of distal clearance, total excision of the mesorectum, and pelvic lymphadenectomy is stressed. METHODS AND RESULTS: The rationale for determining a pelvic lymphadenectomy is identified in the high percentage (20 percent) of lateral endopelvic metastatic nodes demonstrated in cases of extraperitoneal rectal cancers. The results after pelvic lymphadenectomy and the eventual complications are observed. The autonomic nerve-sparing procedure is described and the preliminary results, with a decreased rate of urinary and sexual sequelae, are discussed. CONCLUSIONS: It was concluded that, in cases of an advanced rectal cancer, radical surgery, if associated with the nerve-sparing technique, can improve survival without affecting the incidence of major complications.

Humans↗
PubMed1994

Activation of inositol phospholipid turnover and calcium signaling in rat Sertoli cells by P2-purinergic receptors: modulation of follicle-stimulating hormone responses.

To study the role of extracellular nucleotides in the regulation of Sertoli cells, the effects of ATP and its analogs on the Ca(2+)-phospholipid- and cAMP-dependent pathways were tested. Cultured Sertoli cells from immature animals were incubated with ATP or structurally related compounds, and phosphoinositide (PI) turnover or cAMP accumulation was measured. Among the several nucleotide phosphate analogs tested, adenosine 5'-O-(3-thiotriphosphate) was the agonist most potent in stimulating inositol phosphate accumulation. The effects of purine nucleotides on PI turnover were time and concentration dependent. Because nonhydrolizable ATP analogs also stimulated PI turnover, ATP metabolites or metabolic products are not responsible for the observed stimulation. The order of potency of the different ATP analogs [adenosine 5'-O-(3-thiotriphosphate) > ATP approximately equal to UTP > beta, gamma-methyleneadenosine 5'-triphosphate, 2-methylthio-ATP > adenosine] was consistent with the presence of P2U receptors (nucleotide receptors) on the surface of the Sertoli cell. Augmented PI turnover was accompanied by a transient increase in Ca2+ concentration, measured in single Sertoli cells loaded with the intracellular Ca2+ indicator fura-2. When used alone, ATP and its analogs did not have a direct effect on cAMP levels in the Sertoli cell. However, ATP or its analogs inhibited FSH-dependent cAMP accumulation by more than 70%. Purine nucleotides also efficiently blocked the effects of FSH distal to cAMP accumulation, because extracellular ATP completely reversed the changes in Sertoli cell shape induced by FSH. The nucleotide-dependent inhibition of cAMP accumulation was blocked by pertussis toxin to a different degree depending on the purine or pirimidine nucleotide used. This indicated that more than one mechanism contributes to the purine nucleotide-dependent inhibition of cAMP accumulation. These data provide evidence that purine nucleotide receptors coupled to multiple pathways are present on the Sertoli cell in culture, and that extracellular ATP has profound biological effects on the FSH responsiveness of the Sertoli cell.

Adenosine↗
PubMed1994

[A histological and ultrastructural study of the effects of the argon laser scalpel on the kidney].

The authors carried an histological and ultrastructural study on rat kidney following polar excision by argon laser. The involvement of the remainder portion of the kidney was evaluated analysing the depth of the damage induced by the laser radiation. Restitution ad integrum was found below 360 micron thickness with a different involvement of the various kidney components. Glomeruli showed a deep damage caused by intravascular photocoagulation. On the contrary, tubular and extracellular damage was less serious and the damaged area extended for only 240 micron from the section, probably for a lack of absorbance of the argon radiation by clear and water-rich tissues.

Animals↗
PubMed1993

Rat testicular myoid cells respond to endothelin: characterization of binding and signal transduction pathway.

The presence of endothelin (ET), a vasoconstrictor peptide, in the testis suggests that it may regulate nonvascular target cells. We investigated binding ability, regulation of inositol phosphate metabolism, changes in cytosolic free Ca2+ concentrations ([Ca2+]i), and induction of morphological changes by ET-1 in rat primary testicular myoid cell cultures. ET-1 specifically bound to highly purified rat testicular myoid cells in a time- and temperature-dependent manner. Scatchard analysis of the binding studies indicated the presence of a single class of high affinity binding sites, with an apparent Kd of 3 x 10(-10) M and a maximal binding capacity of 10(5) sites/cell. ET-1 induced both rapid production of inositol triphosphate and mobilization of [Ca2+]i in a concentration-dependent fashion. By contrast, inositol lipid metabolism was slightly affected by ET-1 in the total peritubular cell population. Purified Sertoli cells failed to show either ET-1 binding or ET-1-induced phosphatidylinositol hydrolysis. Mobilization of [Ca2+]i mostly depended upon the release of Ca2+ from thapsigargin-sensitive intracellular Ca2+, whereas it was not affected by abolishment of the Ca2+ gradient through the plasma membrane or by inhibition of L-type voltage-sensitive Ca(2+)-channels by nifedipine. These findings together with the fact that Sertoli cells are unable to respond to and bind ET-1 indicate that ET is a specific agonist of myoid cells in the seminiferous tubule and suggest a role for ET-1 in the autocrine/paracrine regulation of testicular function.

Animals↗
PubMed1992

Immunosuppressive molecules produced by Sertoli cells cultured in vitro: biological effects on lymphocytes.

In the present study we have analyzed the proteins secreted in vitro by murine Sertoli cells to identify immunosuppressive factors. Our data show that Sertoli cells secrete molecules capable to inhibit proliferation of lymphocytes activated in vitro. Cytophluorimetric analysis indicates that treated cells are arrested in the G1 phase of cell cycle. The inhibitory activity is specific for both B or T lymphocytes but not for other non-lymphoid cells and is associated to proteins, heat and freeze stable, with Mr of more than 30 kDa. Lymphocytes treated with Sertoli immunosuppressive proteins drastically reduce the secretion of interleukin-2.

Animals↗
PubMed1992

Steroid-dependent form of Kinsbourne syndrome: successful treatment with trazodone.

We report the case of a 19 month old girl with myoclonic encephalopathy of infants (MEI) (Kinsbourne syndrome), on long-term therapy with ACTH for the occurrence of frequent relapses (steroid-dependent form). The administration of trazodone per os at low doses as an alternative to the previous treatment ensured complete remission, also on the occasion of a subsequent relapse. No rebound effects were observed after trazodone withdrawal (10 months). At present, 3 years after withdrawal of the therapy, the child is well and free from symptoms. The hypothesis that trazodone may be effective in treating MEI, at least in cases that are steroid-dependent or resistant to ACTH, appears highly interesting. Trazodone is proposed as a possible alternative to treatment with ACTH.

Adrenocorticotropic Hormone↗
PubMed1992

[Malignant fibrous histiocytoma of the pancreas].

The authors report a case of pancreatic malignant fibrous histiocytoma (approximately 22 cm). Clinical and instrumental approach for preoperative diagnosis is discussed and the anatomopathological features of the lesion, which is rarely localized in the pancreatic gland, are stressed. Surgical treatment is outlined as well.

Female↗
PubMed1991

Comparative studies of the cytotoxic T lymphocyte-mediated cytotoxicity and of extracellular ATP-induced cell lysis. Different requirements in extracellular Mg2+ and pH.

We recently proposed that extracellular ATP (ATPo) may be involved in CTL-mediated cytotoxicity by acting in concert with yet unidentified cellular components (ATPo receptors/ATPo-binding proteins, ectoprotein kinases). The TCR-triggered ATPo accumulation by CTL has been demonstrated, whereas the resistance of CTL to ATPo was explained by the action of highly active ecto-ATPases or by the absence of relevant ATP-binding proteins. However, no data were available to discriminate between the possibilities of: i) ATPo acting alone as a "hit" molecule because of the cell-permeabilizing properties of ATP4- or ii) ATPo acting as a "messenger" (as MgATP2-) in concert with other molecules. Comparing ATPo-induced and CTL-mediated cell lysis, we found that ATPo-induced lysis of some target cells is greatly decreased at neutral and acidic pH, whereas Ca(2+)-dependent CTL-mediated lysis of the same cells is barely affected. In agreement with the observed pH dependency, at low Mg2+ concentrations, which favor ATP4- over MgATP2-, maximal ATPo-induced lysis was observed. However, CTL-mediated cytotoxicity in both Ag-specific and retargeting assays was markedly reduced at low Mg2+ concentrations. These results suggest that ATPo acting alone as a "hit" molecule cannot fully account for the extracellular Ca(2+)-dependent lethal hit delivery by CTL or that ATP4- is active at very low concentrations. This conclusion was further supported by studying the lytic effect of ATPo and CTL on the anti-TCR mAb-coupled SRBC. CTL were efficient in the SRBC lysis, whereas no lysis of SRBC by ATPo was detected. The resistance of SRBC to ATPo is not caused by a high ATPo degradation, because the ecto-ATPase activity of SRBC was much lower than in ATPo-resistant CTL OE4 cells and comparable with EL4 tumor cells, which were easily lysed by ATPo. These data suggested the need for careful consideration of the pH and cation composition of the media used for studying ATPo effects. The caveats in the use of ATP-degrading enzymes to implicate the role of extracellular ATPo in the CTL-mediated cytotoxicity are described here. A clarification of the previously described cytotoxicity inhibition by hexokinase, which is caused by an inhibitory salt effect, is presented. It is suggested that if Ca(2+)-dependent lysis of SRBC and of other target cells by CTL does involve extracellular ATP, it may function as a "messenger" in concert with other extracellular molecules.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphate↗
PubMed1990

Ecto-ATPase activity in cytolytic T-lymphocytes. Protection from the cytolytic effects of extracellular ATP.

Addition of ATP or ATP analog to the incubation media is shown to result in cell death in experiments with different cultured cell lines as evidenced by the results of several independent assays, both in the absence or presence of extracellular Ca2+. Cytolytic T-lymphocyte (CTL) clone itself was not only resistant to cytolytic effects of ATP, but was able to "rescue" antigen-nonbearing 51Cr-labeled cells from lytic effects of extracellular ATP (but not from lytic effects of adenosine 5'-thiotriphosphate) when present during assay. To test whether the resistance of CTL to ATP is due to a high activity of ecto-ATPase, four independent assays of ATPase activity were utilized to demonstrate the presence and relatively high activity of the ecto-ATPase(s) on CTL surface. Studies of substrate specificity of CTL ecto-ATPase suggest that there is more than one nucleoside 5'-triphosphatase on the surface of CTL. The enzyme(s) activity is Ca2+- and Mg2+-dependent and in this respect is similar to recently described hepatic cells ecto-ATPase. We tested effects of known ATP-binding site-specific reagents fluorescein 5'-isothiocyanate (FITC) and 5'-fluorosulfonylbenzoyladenosine (FSBA) to find covalent modification procedures to be used in studies of functional role of ecto-ATPase. FSBA, but not FITC, inhibits lymphocyte ecto-ATPase but addition of ATP together with FSBA protects ecto-ATPase activity. Inactivation of CTL ecto-ATPase by pretreatment with FSBA makes CTL susceptible to lytic effects of extracellular ATP, as was hypothesized for the functional role of this enzyme in CTL.

Adenosine↗
PubMed1990

Extracellular ATP in T-lymphocyte activation: possible role in effector functions.

We hypothesized that cytolytic T lymphocytes (CTL) may utilize extracellular ATP (ATPo) during the effector phase of the CTL-target cell interactions and that CTL could be the source of ATPo. It is demonstrated here that incubation of CTL with activating ligands [Con A or monoclonal antibody (mAb) to the T-cell antigen receptor (TCR)] results in the extracellular Ca2(+)-independent accumulation of the ATPo. The addition of the ATP-degrading enzymes into the mixture of CTL and target cells results in a strong inhibition of the CTL-mediated, TCR-triggered lethal-hit delivery to the target cell. In a parallel control experiment, the employed enzymes did not affect target cell-induced, TCR-triggered exocytosis of granules from CTL. Thus, the removal of ATPo with enzymes does not interfere with the activation of CTL by the target cell but does block lytic events. Cloned helper T lymphocytes also accumulate ATPo after incubation with anti-TCR mAb or Con A, suggesting the possibility that ATPo, which acts in concert with ectoprotein kinases and/or purinergic receptors, may be of general use as a messenger in cellular interactions of T lymphocytes.

Adenosine Triphosphatases↗