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M Paolucci

Publications and source records attributed to M Paolucci.

At least 37 records · Page 2Linked to original sources
PubMed1998

Characterization of progesterone-binding moieties in the little skate Raja erinacea.

In this study we report evidence of a [3H]progesterone-binding moiety in the liver and oviduct of the little skate Raja erinacea. It is characterized by high affinity, low capacity and DNA-cellulose-binding activity. Furthermore Western blot analysis revealed that monoclonal antibodies against the chicken progesterone receptor (PR) subunits A and B cross-reacted with a 110-kDa band in the liver and a 80-kDa band in the oviduct. When analyzed by DEAE-Sepharose ion-exchange column chromatography, [3H]progesterone-binding molecules resolved into two peaks, one nonadherent and one adherent to the column. The liver adherent peak eluted in a linear gradient at a NaCl concentration of about 0.07 M and resolved on Western blot as a single band of a 110 kDa. The oviduct adherent peak eluted at about 0.14 M NaCl and resolved on Western blot as a single band of 80 kDa. Competition studies showed that the progesterone-binding moiety in the cytosol was specific for progesterone. On the contrary, the nuclear component is not specific for progesterone; it also binds testosterone and estradiol 17 beta in the oviduct, and progesterone, testosterone, dihydrotestosterone, estradiol 17 beta, mibolerone, and R5020 in the liver. The [3H]progesterone-binding activity was monitored in both liver and oviduct of females in different reproductive stages. Females were separated into three groups; laying, nonlaying, and immature. [3H]Progesterone-binding activity levels were higher in the liver of immature than of nonlaying skates, and it was undetectable in laying skates. [3H]Progesterone binding was higher in the oviduct of laying and nonlaying skates than of immature skates. This PR-binding moiety has many characteristics of a true receptor: high affinity, low capacity, binds to DNA, and cross-reacts with antibodies against chicken PR. However, while the cytosolic form of this progesterone-binding component was quite specific for P, nuclear extracted material was nonspecific. If these progesterone-binding components are homologous with the PR A and PR B forms of other vertebrates, as we believe, it is clear that there are species differences that probably relate to phylogenetic level and physiology of the organism.

Animals↗
PubMed1998

Apolipoproteins and their electrophoretic pattern throughout the reproductive cycle in the green frog Rana esculenta.

Lipoprotein fractions in Rana esculenta were separated using the same salt intervals currently applied for human lipoproteins. Very low density lipoproteins (VLDL), low density lipoproteins (LDL) and high density lipoproteins (HDL) were analyzed with reference to the electrophoretic pattern. The lipoprotein electrophoretic pattern in males and females throughout the reproductive cycle showed minor differences. In general, each fraction was characterized by a specific apolipoprotein content. VLDL and LDL fractions were dominated by a high molecular weight (MW) band, most likely the counterpart of human Apolipoprotein B (apo B). The apo B in R. esculenta cross reacted, although weakly, with antibodies raised against chicken apo B. The HDL fraction showed a band with an apparent MW of 29 kDa. The electrophoretic mobility of the protein moiety of HDL was similar to human apolipoprotein A-I (apo A-I). However, HDL apolipoprotein of R. esculenta did not cross react with antibodies against chicken apo A-I under either denaturing or native conditions. The HDL apolipoprotein of R. esculenta was purified by DEAE-Sephacel chromatography followed by HPLC. Its amino acid composition showed a moderate correlation with trout, salmon, chicken and human apo A-I.

Amino Acids↗
PubMed1996

A computerized connectivity approach for analyzing the structural basis of mutagenicity in Salmonella and its relationship with rodent carcinogenicity.

We have applied a new software program, based on graph theory and developed by our group, to predict mutagenicity in Salmonella. The software analyzes, as information in input, the structural formula and the biological activities of a relatively large database of chemicals to generate any possible molecular fragment with size ranging from two to ten nonhydrogen atoms, and detects (as predictors of biological activity) those fragments statistically associated with the biological property investigated. Our previous work used the program to predict carcinogenicity in small rodents. In the current work we applied a modified version of the program, which bases its predictions solely on the most important fragment present in a given molecule, considering as practically negligible the effects of additional less important fragments. For Salmonella mutagenicity we used a database of 551 compounds, and the program achieved a level of predictivity (73.9%) comparable to that obtained by other authors using the Computer Automated Structure Evaluation (CASE) program. We evaluated the relative contributions of biophores and biophobes to overall predictivity: biophores tended to be more important than biophobes, and chemicals containing both biophores and biophobes were more difficult to predict. Many of the molecular fragments identified by the program as being strongly associated with mutagenic activity were similar to the structural alerts identified by the human experts Ashby and Tennant. Our results tend to confirm that structural alerts useful to predict Salmonella mutagenicity are generally not very strong predictors of rodent carcinogenicity. Although the predictivity level achieved for oncogenic activity improved when the program was directly trained with carcinogenicity data, carcinogenicity as a biological endpoint was still more difficult to predict than Salmonella mutagenicity.

Animals↗
PubMed1996

In vitro effects of beta-endorphin on testicular release of androgens in the lizard Podarcis sicula Raf.

The effects of the proopiomelanocortin-derived opioid peptide, beta-endorphin (beta-EP), and of the opioid antagonist, naloxone (NAL), on both basal and pituitary-stimulated androgen secretion from superfused quiescent and active testes were assessed in the adult lizard, Podarcis sicula. In the absence of the homologous pituitary, in vitro treatment with beta-EP and/or NAL did not affect basal secretion of androgens from quiescent and active testes. Conversely, in the presence of the homologous pituitary, treatment with beta-EP brought about a decrease in androgen secretion in active testes, but no effect on quiescent ones. Naloxone counteracted the inhibitor effect of beta-EP in active testes, and enhanced maximal pituitary-stimulated secretion of androgens in quiescent but not in active testes. The effects produces by beta-endorphin and naloxone were reversible. These results suggest that, in this lizard, opioids might be involved in the control of androgen release. The lack of effect of beta-EP and naloxone when added directly to the testes seems to suggest that the opioid agonist and antagonist act on androgen release by modulating pituitary gonadotrophin output.

Androgens↗
PubMed1995

Molecular fragments associated with non-genotoxic carcinogens, as detected using a software program based on graph theory: their usefulness to predict carcinogenicity.

We assembled 390 chemicals with a structure non-alerting to DNA-reactivity (145 carcinogens and 245 non-carcinogens) for which rodent carcinogenicity data were available. These non-alerting chemicals were defined by the absence in their molecules of DNA-reactive (directly or after metabolic activation) alerting structures, as described by Ashby and coworkers (Mutat. Res., 204 (1988) 17-115; Mutat. Res., 223 (1989) 73-103; Mutat. Res., 257 (1991) 209-227; Mutat. Res., 286 (1993) 3-74). Using our software program based on graph theory we analyzed the compounds in order to estimate the program's ability to predict nonalerting carcinogens. Our software fragmented the structural formula of the chemicals into all possible fragments of contiguous atoms with size between 2 and 8 (non-hydrogen) atoms and learned about statistically significant fragments from a training set of chemicals. These fragments were used to predict carcinogenicity or lack thereof in a verification set of compounds. For 390 runs of the software program we used (n - 1) of the chemicals as a training set, to predict the excluded chemical at each run (as a test set). Using two different probability thresholds to select significant fragments (P = 0.05 and P = 0.125 1-tailed according to binomial distribution), we performed two analyses: in the better one (P = 0.05) 19% of the molecules tested lacked significant fragments, for the remaining 81% the observed level of accuracy of the prediction was 66.0% against an expected level of accuracy of 51.7%. The difference was highly significant (P < 0.0001). We also examined the more significant activating fragments (biophores) and discussed at length both their biological plausibility and the working hypothesis that additional alerting structures for carcinogenicity (not only those related to genotoxicity) can be detected using this type of SAR approach. This new class of alerting structures could identify subfamilies of congeneric analogs active through mechanisms of receptor mediated carcinogenesis.

Carcinogens↗
PubMed1995

Distribution and characterization of apolipoproteins in Chrysemys picta plasma.

Very low density lipoproteins (VLDL) (d < 1.006), low density lipoproteins (LDL) (1.006 < d < 1.063), and high density lipoproteins (HDL) (1.063 < d < 1.21) were isolated by ultracentrifugation from the plasma of female and male Chrysemys picta. The protein components of lipoproteins (apolipoproteins) were analysed by electrophoresis in denaturing polyacrylamide gradient gel. Gel filtration chromatography, electroelution from gradient gel and two dimensional electrophoresis were utilized to partially purify and characterized the main apolipoproteins. A 350 kDa Apo B-like protein was found associated with VLDL and LDL fractions. In HDL, Apo AI was the main protein component which, after purification on Sephadex G-200, showed the same electrophoretic mobility as human Apo AI (28 kDa). When analysed by two dimensional electrophoresis, Apo AI gave a pI value of 5.2. A 36 kDa apolipoprotein was purified from VLDL fraction. The purified putative Apo E showed an electrophoretic mobility slightly lower than human Apo E (34 kDa). The only sex difference observed was a band in the female bottom fraction (d > 1.21) with similar electrophoretic mobility to vitellogenin.

Animals↗
PubMed1994

Sex steroid binding proteins in the plasma of the green frog, Rana esculenta: changes during the reproductive cycle and dependence on pituitary gland and gonads.

Sex steroid binding proteins (SSBP) have been reported in the plasma of female and male Rana esculenta. In both sexes SSBP bind [3H]estradiol and [3H]testosterone with medium-high affinity and high specificity. Using ion-exchange chromatography SSBP resolve into two peaks eluting at 0.27 M (peak I) and 0.36 M (peak II) NaCl. Both peaks bind [3H]estradiol and [3H]testosterone equally well. Isoelectrofocusing showed that peak I focused at pH 6.0 and 7.5, whereas peak II focused at pH 6.0. SSBP capacity for [3H]estradiol and [3H]testosterone changes throughout the reproductive cycle, showing low levels during the nonbreeding period and increasing levels during the breeding period. Hypophysectomy and/or gonadectomy result in small changes in SSBP capacity. Short-term steroid hormone treatment of gonadectomized animals does not modify SSBP capacity.

Animals↗
PubMed1994

Opioid peptides and testicular activity in the lizard Podarcis s. sicula Raf.

In mammals endorphinergic systems have been shown to modulate reproductive processes and beta-endorphin (beta-EP) has been found to influence sexual functions, acting at the hypothalamus-pituitary-gonadal axis level. Using immunocytochemical and in vitro studies, evidence for a diffuse pro-opiomelanocortin-related opioid system in the lizard Podarcis s. sicula was produced. In the testis, beta-EP immunoreactivity showed seasonal variation, being most pronounced in the interstitial cells of sexually quiescent lizards (December). Reverse-phase high-performance liquid chromatography, coupled with radioimmunoassay and immunocytochemistry, showed that beta-EP and acetyl beta-EP increased during December, while their concentrations were low during April, when the highest testicular activity occurred. Using in vivo studies, it was found that naltrexone treatment, blocking pituitary opioid receptor, increased androgen levels in the plasma and in the testis. It was also found with in vitro studies that the endogenous opioid system inhibits gonadotrophin release and therefore androgen production by the testis. The data reported here provide evidence for the physiological role played by opioid peptides at the pituitary level to regulate the seasonal reproductive activity of the lizard Podarcis s. sicula.

Androgens↗
PubMed1993

Changes in ovarian follicles and in vitro sex hormone release in the lizard Podarcis sicula sicula.

An in vitro superfusion method was used to test sex hormone release from different kinds of ovarian follicle (growing follicles, postovulatory follicles, and atretic follicles) in the lizard Podarcis sicula sicula. Sex hormone output changes with the stage of follicle evolution and sexual cycle. Previtellogenetic follicles prevail in early-spring quiescent ovaries and secrete mainly progesterone, which is probably utilized at that phase to delay ovarian resumption. In the acute ovary, progesterone output from previtellogenetic follicles decreases, whereas vitellogenetic follicles produce a significant amount of 17 beta-estradiol, which is necessary for sustaining vitellogenin synthesis by the liver and oviduct growth. As follicles become ripe, progesterone production is resumed, and it increases in young postovulatory follicles. This is in line with the functions assigned to the hormone at that phase of the sexual cycle, i.e., the induction of oocyte maturation and the regulation of egg retention in the oviduct. Postovulatory follicles can also synthetize 17 beta-estradiol. After oviposition, this hormone, which is secreted by the old postovulatory follicles, can reinitiate vitellogenin synthesis, allowing the development of a new oocyte set. Our data confirm that active, although ephemeral, corpora lutea are also formed in oviparous species. A limited contribution to ovarian sex steroid production derives also from atretic follicles, at least at the early stages of the breeding cycle.

Animals↗
PubMed1993

Relationship between molecular connectivity and carcinogenic activity: a confirmation with a new software program based on graph theory.

For a database of 826 chemicals tested for carcinogenicity, we fragmented the structural formula of the chemicals into all possible contiguous-atom fragments with size between two and eight (nonhydrogen) atoms. The fragmentation was obtained using a new software program based on graph theory. We used 80% of the chemicals as a training set and 20% as a test set. The two sets were obtained by random sorting. From the training sets, an average (8 computer runs with independently sorted chemicals) of 315 different fragments were significantly (p < 0.125) associated with carcinogenicity or lack thereof. Even using this relatively low level of statistical significance, 23% of the molecules of the test sets lacked significant fragments. For 77% of the molecules of the test sets, we used the presence of significant fragments to predict carcinogenicity. The average level of accuracy of the predictions in the test sets was 67.5%. Chemicals containing only positive fragments were predicted with an accuracy of 78.7%. The level of accuracy was around 60% for chemicals characterized by contradictory fragments or only negative fragments. In a parallel manner, we performed eight paired runs in which carcinogenicity was attributed randomly to the molecules of the training sets. The fragments generated by these pseudo-training sets were devoid of any predictivity in the corresponding test sets. Using an independent software program, we confirmed (for the complex biological endpoint of carcinogenicity) the validity of a structure-activity relationship approach of the type proposed by Klopman and Rosenkranz with their CASE program.

Carcinogens↗
PubMed1992

Plasma sex steroid binding proteins (SSBP) in the male lizard, Podarcis s. sicula, during the reproductive cycle.

In male Podarcis s. sicula plasma, a sex steroid binding protein [SSBP(s)] binds testosterone (T) and estradiol-17 beta (E2) with moderate affinity (Kd = 0.23 +/- 0.08 x 10(-8) for 3H-E2, and 0.24 +/- 0.07 x 10(-8) for 3H-T) and high capacity. The SSBP binding affinity is unchanged throughout the sexual cycle, although its capacity is higher in nonreproductive males (winter and postreproductive period). This change may be related to changes in plasma T and E2 levels, and is likely to be involved in mechanisms whereby free steroid is delivered to target organs. SSBP, under isoelectrofocusing, is distributed between pH 5.5-6.5 and pH 7.1-7.5. The concentration of these two forms varies during the annual cycle.

Analysis of Variance↗
PubMed1992

Seasonal fluctuations of androgen-binding activity in the testis of the frog, Rana esculenta.

An androgen-binding activity has been identified in nuclear extracts of the testis of the frog, Rana esculenta. A single class of high affinity (Kd = 2.5 +/- 0.6 x 10(-9) M), low-capacity binding sites was found. The binding was specific for androgens; 17 beta-estradiol displaced [3H]testosterone with an ID50 of 0.1 microM. Cytosolic binding activity has a low affinity and a high capacity and lacks specificity. The seasonal fluctuations in binding capacity did not correlate with the androgen peaks in plasma and testes between February and June and in September; periods coinciding with the resumption of spermatogenesis and the development of spermatids, respectively. The present data strongly support androgenic control of intratesticular function in vertebrates generally.

Androgens↗
PubMed1992

Putative steroid-binding receptors and nonreceptor components and testicular activity in the lizard Podarcis sicula sicula.

Labelled testosterone- and oestradiol-binding molecules have been found in the cytosol and nuclei of lizard testes. DNA-cellulose affinity chromatography was used to separate putative sex-steroid-binding receptors (adhering molecules) and nonreceptor components (nonadhering molecules). A putative androgen receptor (Kd: 10(-10) mol l-1; 3-9 fmol g-1 tissue) was found mainly in the nuclei of testicular cells when actively undergoing spermatogenesis. This suggests that, as in higher vertebrates, testosterone is implicated in spermatogenetic step regulation (meiosis and spermiogenesis) in lizard testis. In the cytosol, testosterone-binding molecules (Kd: 10(-9) mol l-1; 384-784 fmol g-1 tissue) with several properties of androgen-binding proteins are present from autumn to spring. The behaviour of these molecules is consistent with the role assigned to androgen-binding proteins as androgen reservoir. A putative oestrogen receptor is present throughout the sexual cycle, except during the culmination phase (breeding). The putative oestrogen receptor may be involved in the regulation of the first spermatogenetic step (spermatogonia multiplication) and in the induction of post-reproductive refractoriness. This phase is present in temperate-zone lizards. These studies show that the evaluation of sex-steroid-binding molecules is useful in considering the relationships between sex hormones and spermatogenetic activity in the testes of lizards.

Analysis of Variance↗
PubMed1991

[Diseases detected with defecographic examination in 300 patients].

Defecography is a radiological examination providing morphological details of the anorectal tract. Over almost 3 years, 300 patients were examined. The authors report on the method and the pathologic conditions they observed. The patients were seated in latero-lateral position on a radiolucent water-filled commode: lead marks were taped to define perianal skin. 150 ml of high-density barium paste were introduced into the rectum and radiographs were then acquired, at rest and during squeezing and straining. All examination phases, especially the study of dynamic evacuation, were recorded on a videotape connected to a brilliance intensifier. From their experience, the authors conclude that defecography is a valuable tool in the diagnosis and evaluation of: rectocele, occult rectal prolapse, and elevator ani tone. The technique proved less useful in the evaluation of fecal incontinence. The authors strongly suggest that the patient be previously examined by a coloproctologist. Defecography is thought to help the surgeon in the choice of therapy, together with other diagnostic procedures and with clinical history.

Adult↗
PubMed1989

Estradiol receptor in the lizard liver (Podarcis s. sicula). Seasonal changes and estradiol and growth hormone dependence.

This study shows that in the liver of the oviparous lizard, Podarcis s. sicula, the estrogen receptor (ER) level increases during the reproductive period (spring) when vitellogenesis occurs. This phenomenon interested both unfilled and filled ER present in the cytosolic and nuclear fractions. The increase in unfilled cytosolic and filled nuclear receptor was positively correlated to the plasma level of vitellogenin. The level of liver ER approximated that of mammalian liver ER and, therefore, it is higher than that reported for the liver of several nonmammalian species. At electrofocusing, liver ER distributes in two pH ranges (pH 6.5-7.5 and 8.0-8.8, respectively). The first form predominated in nuclei of reproductive females or of spayed estrogenized females and could represent the activated form of receptor. Ovariectomy was followed by a decrease in liver ER which can be induced in spayed females by estradiol administration. Pituitary growth hormone (GH) seemed to exert a synergic effect on estradiol liver estrogen receptor regulation. In lizards treated both with estradiol and GH, in fact, there was a significant increase in nuclear filled ER rather than an increase in the level of total nuclear ER.

Animals↗
PubMed1988

Estradiol-binding molecules in the hepatocytes of the female water frog, Rana esculenta, and plasma estradiol and vitellogenin levels during the reproductive cycle.

Estradiol-binding molecules have been found both in cytosol and nuclear extract of hepatocytes of the female green frog Rana esculenta. These molecules show the properties of an estradiol receptor (Re): high and specific affinity for estrogens (2.10-7.10 x 10(-10) M), stability of binding at 0 and 20 degrees, localization in the nucleus, and cytosolic versus nuclear binding shift in estradiol-treated frogs. In hepatocytes, both filled and unfilled Re is detectable in all stages of the R. esculenta annual cycle. It increases during the recovery phase (September to January) when vitellogenetic processes are active in the ovary. These changes are positively correlated with vitellogenin. Only nuclear filled Re, moreover, is positively correlated to level of circulating estradiol. This suggests a direct connection: plasma estradiol level versus nuclear filled Re versus plasma vitellogenin level.

Animals↗
PubMed1982

Sex differences in liver non-specific esterases of the green frog Rana esculenta.

1. Liver esterases of the green frog Rana esculenta have been fractionated on disc electrophoresis, thin-layer electrofocusing and column electrofocusing. 2. The enzyme resolves in several molecular forms some of which result sex dependent, since they disappear in castrated animals and can be induced by sex hormone administration. 3. The enzyme molecular forms which depend on female hormones might be involved in cellular modifications of hepatocytes related to yolk protein synthesis. induced by sex hormone administration. 3. The enzyme molecular forms which depend on female hormones might be involved in cellular modifications of hepatocytes related to yolk protein synthesis.

Animals↗