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B Marchetti

Publications and source records attributed to B Marchetti.

87 records · Page 5Linked to original sources
PubMedDate not supplied

Phosphatidylserine counteracts physiological and pharmacological suppression of humoral immune response.

Phosphatidylserine (PS) is a necessary cofactor for protein kinase C (PKC) activation, and changes in the synthesis of PS have been shown to participate in the mechanism(s) involved in the transmembrane signaling of interleukin 1 (IL-1). In view of the age-associated defects in T-cell functions, in the present study we have addressed the question of whether an in vivo treatment with PS might interfere with such processes. Furthermore, the effect of an in vitro treatment with PS in human peripheral blood monocytes (PBMC) or splenocytes activated with a lectin mitogen, on the expression of IL-2 receptor, was assessed. While the process of ageing was accompanied by a marked decline of humoral response monitored by anti-BSA antibodies (of the IgG class) production, following immunization with BSA in complete Freund adjuvant, chronic treatment with PS (50 mg/kg, in drinking water), reversed this effect, raising specific antibody titers to levels practically indistinguishable from those measured in young animals. Pharmacological depression of humoral immune response induced by a treatment of adult animals with dexamethasone was similarly reversed by a chronic treatment with PS. While only a pharmacological concentration (10(-5) M) of PS significantly increased IL-2 receptor expression in activated human PBMC, simultaneous treatment of PBMC with inactive doses of PS and the pharmacological activator of PKC (phorbol myristate acetate, PMA, 10(-8) M) resulted in a synergistic stimulation of Tac+ cells. Furthermore, in cultures of rat splenocytes PS (10(-6) M) significantly stimulated the expression of IL-2 receptor, and concomitant addition of PS (10(-7) M) to Con A-stimulated splenocytes produced a significant potentiation of IL-2 receptor induction. The present results indicate that in vivo treatment of ageing animals with the specific phospholipid PS is able to reverse the physiological decline of the humoral immune response induced by the ageing process. Moreover, treatment of young rats with PS reversed the pharmacological associated depression of specific antibody production. The in vitro effects of the phospholipid on human PBMC and rat splenocytes might suggest that PS is implicated in T-cell activation through its action on IL-2 receptor.

Aging↗
PubMedDate not supplied

Modulation of hippocampal LHRH receptors by sex steroids in the rat.

The modulation of brain LHRH receptors by sex steroids was assessed in the female rat hippocampus using in vitro autoradiography and iodinated [D-Ser (TBU)6, des-Gly-NH2(10)]LHRH ethylamide as the radioligand. As evaluated by optical densitometry, the density of hippocampal LHRH receptors was increased by castration. In castrated animals, estradiol administration produced a small decrease in receptor concentration, whereas the concomitant administration of progesterone and estradiol as well as the injection of dihydrotestosterone induced a marked decrease in receptor density. Progesterone administration did not produce any significant change in receptor concentration. These results indicate that brain LHRH receptors can be modulated by sex steroids. Interestingly, this modulation of hippocampal LHRH receptors is similar to that previously observed in pituitary gland.

Animals↗
PubMedDate not supplied

Circadian melatonin and young-to-old pineal grafting postpone aging and maintain juvenile conditions of reproductive functions in mice and rats.

Chronic, night administration of melatonin to aging mice and transplantation of a young pineal gland into the thymic rudiment of older mice and rats have been studied with the aim of evaluating their effects on aging of gonadal, sexual, and reproductive functions. Both melatonin administration and young-to-old pineal grafting positively affect size and function of testes and maintenance of juvenile hippocampal and testicular LHRH-receptors and beta-adrenergic receptors in the tests of old rats and mice. These results demonstrate that a pineal-directed circadian function and cyclicity is fundamental for the regulation of sexual, reproductive physiology, and that proper intervention with melatonin may potentially postpone aging of both neural and gonadal sexual function.

Aging↗
PubMedDate not supplied

The LHRH-astroglial network of signals as a model to study neuroimmune interactions: assessment of messenger systems and transduction mechanisms at cellular and molecular levels.

Neurons and astrocytes have a close anatomic and functional relationship that plays a crucial role during development and in the adult brain. Astrocytes in the central nervous system (CNS) express receptors for a variety of growth factors (GFs), neurotransmitters and/or neuromodulators; in turn, neuronal cells can respond to astrocyte-derived GFs and control astrocyte function via a common set of signaling molecules and intracellular transducing pathways. There is also increasing evidence that soluble factors from lymphoid/mononuclear cells are able to modulate the growth and function of cells found in the CNS, specifically macroglial and microglial cells. Furthermore, glial cells can secrete immunoregulatory molecules that influence immune cells as well as the glial cells themselves. As neuronal and immune cells share common signaling systems, the potential exists for bidirectional communication not only between lymphoid and glial cells, but also between neuronal cells and immune and glial cells. In the present work, interactions of luteinizing-hormone-releasing hormone (LHRH) and the astroglial cell are proposed as a prototype for the study of neuroimmune communication within the CNS in the light of (1) the commonality of signal molecules (hormones, neurotransmitters and cytokines) and transduction mechanisms shared by glia LHRH neurons and lymphoid cells; (2) the central role of glia in the developmental organization and pattern of LHRH neuronal migration during embryogenesis, and (3) the strong modulatory role played by sex steroids in mechanisms involved in synaptic and interneuronal organization, as well as in the sexual dimorphisms of neuroendocrine-immune functions. During their maturation and differentiation in vitro, astroglial cells release factors able to accelerate markedly the LHRH neuronal phenotypic differentiation as well as the acquisition of mature LHRH secretory potential, with a potency depending on both the 'age' and the specific brain localization of the astroglia, as well as the degree of LHRH neuronal differentiation in vitro. Regional differences in astroglial sensitivity to estrogens were also measured. Different experimental paradigms such as coculture and mixed-culture models between the immortalized LHRH (GT1-1) neuronal cell line and astroglial cells in primary culture, disclosed the presence of a bidirectional flow of informational molecules regulating both proliferative and secretory capacities of each cell type. The importance of adhesive mechanisms in such cross-talk is underscored by the complete abolition of GT1-1 LHRH production and cell proliferation following the counteraction of neuronal-neuronal/neuronal-glial interactions through addition of neural-cell adhesion molecule antiserum. Other information came from pharmacological experiments manipulating the astroglia-derived cytokines and/or nitric oxide, which revealed cross-talk between the neuronal and astroglial compartments. From the bulk of this information, it seems likely that interactions between astroglia and LHRH neurons play a major role in the integration of the multiplicity of brain signals converging on the LHRH neurons that govern reproduction. Another important facet of neuronal-glial interactions is that concerning neuron-guided migration, and unraveling astroglial/LHRH-neuronal networks might then constitute an additional effort in the comprehension of defective LHRH-neuronal migration in Kallman's syndrome.

Animals↗
PubMedDate not supplied

[Hepatic angiomyolipoma. 2 case reports and review of the literature].

We report two cases of hepatic angiomyolipoma. The first tumor was disclosed at the time of resection of a cardia carcinoma, and temporarily regarded as a possible metastasis. The second tumor was an enormous necrotic mass of the right liver in a young woman mimicking a sarcoma.

Adenocarcinoma↗