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Biomedical subjects

G Mosconi

Publications and source records attributed to G Mosconi.

At least 73 records · Page 4Linked to original sources
PubMed1994

Presence and steroidogenetic activity of beta-endorphin in the ovary of the lizard, Podarcis s. sicula raf.

In mammals, proopiomelanocortin (POMC)-related peptides are involved in reproductive processes at both the hypothalamopituitary and ovarian levels. Through immunocytochemical and physiological in vitro studies, evidence for a diffuse POMC-related opioid system in the lizard Podarcis s. sicula is provided. In the lizard ovary, beta-endorphin (beta-EP)-like immunoreactive cells were observed within the granulosa layer; the immunoresponse showed seasonal variation, being most pronounced in the winter ovary. HPLC followed by immunoassay showed that acetyl beta-EP is the main form of POMC-related peptide in both pituitary and ovary. In vitro studies showed that picomolar amounts of beta-EP stimulate follicular estrogen production during both the reproductive and winter phases; induction was found to be higher in the reproductive phase. The data reported here provide evidence for the physiological role played by beta-EP in the reproductive function of Podarcis s. sicula via induction of ovarian production of estradiol-17 beta, which is the main factor responsible for the vitellogenic process.

Acetylation↗
PubMed1993

In-vitro effects of mammalian and amphibian prolactins on hepatic vitellogenin synthesis in Rana esculenta.

Male and female Rana esculenta liver was induced in an in-vitro system by homologous and Rana catesbeiana pituitary to synthesize and release vitellogenin, a lipoglycophosphoprotein precursor of yolk proteins, lipovitellins and phosvitins, in oviparous vertebrates. In the present experiments, the action of prolactin on hepatic vitellogenin synthesis and release was investigated, using ovine prolactin and Rana catesbeiana prolactin. The effects of prolactin on hepatic vitellogenin synthesis displayed different trends related to sex; male liver was found to be more responsive than female liver to both ovine and frog prolactin; more-over, the response to prolactin was dose-related (r = 0.998; P < 0.05) in male but not in female liver. In both sexes, a high degree of seasonality in the responsiveness of the liver was found, since the vitellogenin levels induced by prolactin during the winter phase were significantly (P < 0.001) higher than those produced during the summer phase. Thus, there was no significant difference between the action of ovine and frog prolactin on vitellogenin synthesis; in fact, mammalian prolactins are structurally similar with regard to nucleotide and amino acid sequences. The direct action of prolactin on hepatic vitellogenin synthesis in the frog Rana esculenta is discussed, on the basis of the role played by prolactin as an important growth modulatory hormone in fetal and adult tissues.

Animals↗
PubMed1993

Strategies in renal failure and the impact of lipids.

The main points to note in terms of strategies in renal failure and the impact of lipids are: 1) Timing and typing of dyslipidemia; 2) Occurrence of dyslipidemia in the course of strategies (conservative, dialysis and transplantation); 3) How the strategies can handle the impact of lipids. Analysis of point 1 confirms what a complex profile uremic dyslipidemia presents, involving the type, class, composition and enzyme systems involved in lipid metabolism. In conservative and dialysis, type IV (triglycerides) predominates; in transplantation, type II (cholesterol). Examination of point 2 shows the non obligatory relationship between dyslipidemia and the various strategies of treatment. Lipid abnormalities, type IV or II, occur in 50-60% of patients. Uremic factors for dyslipidemia include: 1) enhanced hepatic stimulation or altered removal in conservative strategies; 2) the same causes plus "specific" promotors in dialysis (dialysis fluid, plasticizer leaching; bioincompatibility, etc.); 3) steroid therapy and other "accessories" in transplantation. A genetic predisposition is very likely present in all patients. Point 3, finally, analyzes the various "supplements" that each strategy requires to cope with the lipid impact. Generic rules (ranging from doing nothing, to diet, drugs, etc.) are of value in all strategies when dyslipidemia occurs. More specific rules include: a) Conservative strategies: appropriate dietetic optimization and modulation (protein-lipid-carbohydrate ratio in terms of calories); b) Dialysis: timing treatment and improving biocompatibility; c) Transplantation: reducing steroids as much as possible.

Humans↗
PubMed1992

Application of flow cytometry in clinical renal transplantation.

Flow cytometry (FC) may be considered as a fundamental technique in studying cell biology and pathology. It combines the quantitative character of biochemical methods with the multiparametric capacities of microscope analysis in a high-precision process for rapid analysis of individual cell characteristics. Three original FC techniques routinely applied in the field of renal transplantation are reported in the present study. They concern the donor-recipient cross-match test, the morphological analysis of urinary sediment and the modulation of the density of various membrane antigens on the lymphocyte surface. A common factor underlies all these methods: they aim to provide the physician with a reliable diagnostic tool in clinical renal transplantation.

Antigens, Surface↗
PubMed1992

In vitro induction of vitellogenin synthesis in Rana esculenta: role of the pituitary.

Vitellogenin (VTG), a complex protein, is a precursor of yolk protein (lipovitellin and phosvitin) in all oviparous vertebrates studied to date. In amphibians, as in other oviparous vertebrates, VTG synthesis is hormonally dependent; estradiol-17 beta (E2) is especially important, although in vivo in the frog Rana esculenta the pituitary may be involved in hepatic VTG synthesis and secretion. The present in vitro experiments carried out during the main phases of the annual reproductive cycle of this frog showed that homologous pituitary homogenate (HPH), as well as E2, stimulated VTG synthesis in male and female livers, although their patterns of VTG secretion showed some differences with respect to the induction time and the rate of VTG secretion. The hepatic response to HPH occurred after a longer time than that of E2 VTG induction, and no cooperation between HPH and E2 was found in the VTG synthesizing response. It should be emphasized that during the refractory period (July), hepatic VTG synthesis in males and females could only be induced by HPH. These data demonstrate, for the first time, a direct action of HPH on VTG synthesis in male and female frog livers in all the periods tested; hepatic responsiveness to HPH and E2 varies with season and sex.

Animals↗
PubMed1992

Occurrence of immunoreactive Met- and Leu-enkephalin-like peptides in the ovary of the green frog, Rana esculenta.

In the present study, we have localized for the first time Met- and Leu-enkephalin-like material in the ovary of the anuran, Rana esculenta, using the indirect immunofluorescence method. The ovaries were sampled during the main representative phases of the annual reproductive cycle of the frog, living in a mountain pond (Colfiorito, Umbria at 820 m a.s.l.). Strong immunoreactivity to Met- and Leu-enkephalin antisera was observed in the follicle cells of the granulosa layer of vitellogenic oocytes; moreover, during this phase, immunofluorescent materials were also radially localized in the cytoplasm and in the perinuclear zone. The mature oocytes showed Met- and Leu-enkephalin-like immunostaining in the thecal layer and in several granules scattered in the peripheral zone of the yolk. The different pattern of Leu- and Met-enkephalin-like immunoreactivity in the frog ovary parallels and complements the changes occurring in the reproductive (May) and in the vitellogenetic (September) phases during the ovarian cycle. Consequently, these findings strongly support the hypothesis for a local synthesis of these peptides in the ovary and suggest their possible involvement in the control of ovarian function.

Animals↗
PubMed1992

Hormonal control of in vitro vitellogenin synthesis in Rana esculenta liver: effects of mammalian and amphibian growth hormone.

Estradiol 17-beta is known to induce hepatic synthesis and secretion of vitellogenin in all species studied and in Rana esculenta, previous experiments demonstrated the involvement of pituitary in these processes; indeed, in addition to estradiol 17-beta, homologous pituitary homogenate directly stimulated male and female liver to produce vitellogenin in tissue cultures. Therefore, the effect of ovine growth hormone (o-GH) and Rana catesbeiana growth hormone (f-GH) on hepatic vitellogenin synthesis was investigated. In the present in vitro experiments, both o-GH and f-GH positively stimulated vitellogenin synthesis, in female and male liver, in a dose-related fashion. No significant differences were found in VTG levels induced by o-GH and f-GH. The GH stimulatory effects, found during the different phases of the reproductive cycle, displayed different trends related to season and sex.

Animals↗
PubMed1992

Ovarian opioids and the reproductive cycle of the frog Rana esculenta.

In mammals, proopiomelanocortin-related peptides are involved in reproductive processes both at the hypothalamo-pituitary and ovarian levels. Using immunocytochemical, biochemical and physiological "in vitro" studies, we provide here evidence for a diffuse POMC-related opioid system in the frog Rana esculenta. Ovarian beta-endorphin (beta-EP) is expressed in thecal cells and changes during the reproductive cycle in an inverse relationship with follicular development. Seasonal changes in the ovary are different to those in the brain or in the pituitary. The ratio of acetylated vs native beta-EP in the ovary also changes over the reproductive period, affecting the biological activity of the peptide. During both the reproductive spring period and the summer post-reproductive phase pMol amounts of beta-EP stimulate follicular androgen secretion in vitro, in a naloxone-reversible way. In either period, an inhibition of estradiol, possibly mediated via other factors, is the result of opioid action. In conclusion, these data demonstrate for the first time the widespread presence of beta-EP-related peptides in the frog Rana esculenta. Both immunocytochemical and biochemical evidence, as well as in vitro responses, support a physiological role for beta-EP in ovarian seasonality during the reproductive cycle of this amphibian.

Amino Acid Sequence↗
PubMed1992

Epidemiology of hepatitis C in a population of hemodialysis patients.

A search for antibodies against hepatitis C virus (HCV) was performed in 185 patients on chronic hemodialysis by means of 1st and 2nd generation ELISA tests. Immunoblot assays were performed on positive sera. This study shows a 38% prevalence of HCV-positive patients in our dialysis population according to the 2nd generation ELISA test which shows a higher specificity and sensitivity when compared to the 1st generation one (38 vs. 20%). A correlation was found between the prevalence of HCV-positive patients and how long they had been on dialysis and how many blood transfusions they had received.

Cross Infection↗
PubMed1992

[Destructive spondylopathy in the dialysis patient. The diagnostic role of magnetic resonance].

Magnetic resonance imaging (MRI) was employed to study 7 long-term hemodialysis patients affected with destructive amyloid spondyloarthropathy. In the appropriate clinical setting, MRI proved to be more useful than conventional radiography or CT and more definitive in excluding infections. Indeed, MRI can replace more invasive procedures in making the correct diagnosis. Different than what is reported in literature, a high incidence of odontoid lesions (C2) was observed in our series, with extraosseous and extradural deposits of soft tissue masses (amyloid pseudotumors), subluxation, odontoid invagination and medullary compression. Bone lesions, involved disks and amyloid pseudotumors typically exhibited low-intensity signal on both T1- and T2-weighted sequences and no enhancement following Gd-DTPA injection. The use of MRI is thus suggested, especially at cervical level, also in case of relatively mild symptoms.

Aged↗
PubMed1991

Effects of mammalian gonadotropin-releasing hormone on plasma level of prostaglandin F2 alpha in the water frog, Rana esculenta.

The present investigation was performed to evaluate the effects of mammalian gonadotropin-releasing hormone (mGnRH) on prostaglandin F2 alpha (PGF2 alpha) plasma level in adult male and female water frog, Rana esculenta, during three different periods of the reproductive cycle: recovery period (October), breeding period (May), and postreproductive period (June). Intact, hypophysectomized (HYP), gonadectomized (GON), and hypophysectomized-and-gonadectomized (HYP/GON) animals were injected with 0.6 micrograms of mGnRH and sacrificed 1 hr and 5 hr after peptide administration. Some of each of the groups were sacrificed without having received mGnRH. PGF2 alpha plasma levels were assessed by radioimmunoassay. Hypophysectomy induced a significant increase of PGF2 alpha levels in October and June males. mGnRH induced a significant increase of PGF2 alpha plasma levels only in HYP and HYP/GON frogs. The tissue target of this GnRH action is, at present, unknown, although interrenals could be putative responsive tissues. At present, it is also difficult to assign any physiological role to observed phenomena unless to suppose that the pituitary inhibition is not constant throughout the year. It cannot be excluded that the prostaglandin induction depends on a local paracrine action of GnRH, which could be performed outside any pituitary control.

Analysis of Variance↗
PubMed1991

Plasma vitellogenin and 17 beta-estradiol levels during the annual reproductive cycle of Podarcis s. sicula Raf.

Plasma vitellogenin and 17 beta-estradiol concentration were determined during the annual reproductive cycle of the female lizard Podarcis s. sicula Raf. living around Naples. Plasma vitellogenin was purified from estrogenized males for characterization and to raise specific immune serum. Using ELISA, plasma vitellogenin titers were determined in relation to ovary weight; plasma 17 beta-estradiol was measured by RIA method. Native vitellogenin was present as two polypeptide bands: alpha and beta. The electrophoretic patterns, studied in normal male and estrogenized male and female, showed vitellogenin to be a protein present in female and in estrogenized male plasma but not in normal males. Lizard monomeric VTG, determined by SDS-PAGE, was about 200 kDa. Correlations between seasonal ovarian weight variations and plasma vitellogenin and 17 beta-estradiol suggest that ovarian development in Podarcis depends on plasma vitellogenin synthesis, which in turn relies on plasma estradiol levels. The two ovulatory waves observed in this study coincided with the two peak values of plasma vitellogenin and 17 beta-estradiol.

Animals↗
PubMed1991

Ovarian development and sex steroid hormones during the reproductive cycle of Podarcis s. sicula Raf.

Variations in ovary weight and seasonal changes in plasma androgens, 17 beta-estradiol and progesterone have been studied during the reproductive cycle of female Podarcis s. sicula Raf. Adult female Podarcis were captured in the surroundings of Naples during the years 1988 and 1989. Ten lizards were sampled monthly (except in February, August, October and December). Ovaries and oviducts were submitted to morphological examination, and in the blood samples androgens, 17 beta-estradiol and progesterone were assessed by the radioimmunoassay (RIA) method. Ovary weight, expressed as the gonadosomatic index (GSI), presented two statistically significant peak values in April and June, related to the ovulatory waves observed in this study. Several shelled oocytes were also found in the oviducts in this period. Progesterone titers mirrored the modifications of GSI and a very significant correlation (p less than 0.001) between the two parameters can be ascertained. Androgens increased in early spring, peaked in April, and low levels of androgens were found in September and during the winter months. Estradiol titers reached the peak values in March, and, after a sharp decrease in April, remained high until the winter months. The results reported here substantiate the periovulatory changes of the three major gonadal steroids during the annual ovarian cycle of Podarcis s. sicula.

Androgens↗
PubMed1991

Cellular immunology in regular dialysis: a biological model for biocompatibility evaluation.

Cellular immunity represents an interesting biological model for biocompatibility evaluation of artificial materials owing to its sensitivity to contact with the external environment and its capability of modulating response reactions to foreign agents. Advanced methodologies such as flow cytometry and the immunoenzyme techniques in particular have given new insights into lymphocyte structure and functions, enabling analysis of the in vivo modification of these cells. By means of these sophisticated techniques we investigated lymphocyte activation and proliferation during one single haemodialysis session. Findings clearly show that increases in HLA antigen density (class I and II), DNA synthesis, and interleukin-2 receptor serum concentration (Il-2R) take place during the dialysis procedure, and reach their maximum during the first hour of extracorporeal circulation. The relationship between dialysis procedure and cellular immunity appears noticeable and is of potential value in the evaluation and quantification of the biocompatibility of different dialysis membranes.

Adult↗