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N Staiano

Publications and source records attributed to N Staiano.

At least 37 records · Page 2Linked to original sources
PubMed1995

Echistatin inhibits the adhesion of murine melanoma cells to extracellular matrix components.

Echistatin, an RGD containing peptide isolated from Echis carinatus snake venom, inhibited the in vitro attachment of B16-BL6 mouse melanoma cells to fibronectin, vitronectin and laminin. Its inhibitory activity on cell adhesion was non-cytotoxic, dose-dependent and fully reversible. Kinetic analysis showed a competitive type of inhibition for all the three substrates examined here. Chemical reduction and alkylation of echistatin almost abolished its effect on cell adhesion to extracellular matrix components. Native echistatin was also able to inhibit B16-BL6 cell attachment to IgG antihuman fibronectin receptor-coated wells, thus suggesting that the molecule binds to adhesive receptors on melanoma cell surface. Our results indicate that echistatin is an useful disintegrin for research on cell adhesion.

Amino Acid Sequence↗
PubMed1992

Serum beta 2-microglobulin levels and p24 antigen, lymphocyte depletion and disease progression in human immunodeficiency virus infection.

Abnormally elevated serum beta 2-microglobulin levels have been associated with progression of human immunodeficiency virus disease. In this study we have analyzed the relationship between serum beta 2-microglobulin levels of patients at different stages of the disease and serological and immunological parameters commonly used for monitoring the infection. The investigation was performed on 150 patients and 30 controls during the period from March 1989 to March 1990. At that time, 30 patients had the acquired immunodeficiency syndrome or its related complex and 120 had persistent generalized lymphadenopathy or were asymptomatic. Thirty-nine antibody-negative subjects, belonging to a high-risk group for the acquired immunodeficiency syndrome, were used as controls. All patients had normal renal function. There was a significant relationship between increased serum beta 2-microglobulin levels and the presence of p24 antigen, a decrease in the total number of lymphocytes (less than or equal to 1500/mm3) and a decrease in CD4+ T lymphocytes (less than or equal to 200/mm3). No significant relationship between serum beta 2-microglobulin levels and CD3+ T lymphocytes was found.

Adolescent↗
PubMed1991

Effect of enzyme inducers on metabolism of 1-nitropyrene in human hepatoma cell line HepG2.

We measured the response of HepG2 cells to the classic cytochrome (cyt.) P-450 inducers 3-methylcholanthrene (3-MC) and phenobarbital (PB), by evaluating oxidative and/or reductive metabolism of the nitroarenes, 1-NP and 1,6-dinitropyrene (1,6-DNP), in control and induced cells. In HepG2 cells, 3-MC induces ring-hydroxylation of 1-NP, whereas PB stimulates its nitroreduction. PB induces NADPH-cyt. c reductase, but does not affect other cytosolic and microsomal enzymes which contribute to 1-NP nitroreduction in these cells. However, PB-inducible nitroreductase activity seems to be associated primarily with cyt. P-450 isoenzymatic form(s), as indicated by the requirement for NADPH and the response to specific inhibitors such as alpha-naphthoflavone and CO.

Carcinoma, Hepatocellular↗
PubMed1991

Effect of rat liver cytosolic enzymes and cofactors on mutagenicity of 1-amino-8-nitropyrene.

1-Amino-8-nitropyrene (1,8-ANP), a product of 1,8-dinitropyrene metabolism by either bacterial or mammalian enzymes, is weakly mutagenic to the 'classical nitroreductase'-deficient Salmonella tester strain TA98NR. The addition to the test system of rat liver cytosol without cofactors did not produce any effect on the 1,8-ANP mutagenic response toward TA98NR strain. Conversely, when both rat hepatic cytosol and NADPH (1 mM) were added to the mutagenicity assay, a 10-fold increase in 1,8-ANP mutagenic activity was observed. This suggests the involvement of rat hepatic cytosolic NADPH-dependent nitroreductase(s) in 1,8-ANP mutagenic activation. The addition to the mutagenesis assay of pentachlorophenol, an inhibitor of O-acetyltransferase and sulfotransferase, produced a dose-dependent decrease of 1,8-ANP mutagenic activation, whereas 2,6-dichloro-4-nitrophenol, a more specific inhibitor of sulfotransferase than O-acetyltransferase, did not affect the activation of 1,8-ANP to a mutagen at concentrations that selectively inhibit only bacterial sulfotransferase. This indicates that bacterial O-acetyltransferase but not sulfotransferase plays a role in the mutagenic activation of 1,8-ANP. Addition of acetyl co-enzyme A (AcCoA) and adenosine 3'-phosphate 5'-phosphosulfate (PAPS), cofactors for O-acetyl-transferase and sulfotransferase respectively, to the test system caused a dose-dependent inhibition of 1,8-ANP mutagenic activation by rat liver cytosol and NADPH, probably due to the formation of highly reactive O-acetoxy and N-sulfate ester derivatives of 1,8-ANP, which react with nucleophilic sites before reaching bacterial DNA. This hypothesis was confirmed by DNA covalent binding in in vitro experiments showing that both the cofactors AcCoA and PAPS enhanced the NADPH/rat liver cytosol-mediated covalent binding of 1,8-ANP to DNA from calf thymus 10- and 3-fold respectively. It seems likely that rat hepatic cytosolic nitroreductases activate 1,8-ANP to an N-hydroxyarylamine derivative which can be further metabolized to mutagenic species by either bacterial or mammalian O-acetyltransferase.

Acetyl Coenzyme A↗
PubMed1990

Characterization of oxidative and reductive metabolism in vitro of nitrofluoranthenes by rat liver enzymes.

Nitrofluoranthenes (NFs) are mutagenic and carcinogenic environmental pollutants found in incomplete combustion products and urban air particulate. We have studied both oxidative and reductive metabolism in vitro of different NF isomers mediated by subcellular rat liver fractions. Under aerobic conditions only ring hydroxylation of NFs by rat liver microsomes occurred and the isomeric position of the nitro group affected both the amount and the type of phenolic metabolites formed. Liver microsomes from 3-methylcholanthrene-induced rats were most effective in giving ring hydroxylated 7- and 8-nitrofluoranthene, whereas liver microsomes from phenobarbital-pretreated rats were the most active in metabolizing 1- and 3-nitrofluoranthene. Under anaerobic conditions, only reduction of NFs mediated by both cytosolic and microsomal rat liver enzymes occurred. Cofactor requirements and inhibition experiments indicated that the reductase activity in rat liver cytosolic fractions could be ascribed to DT-diaphorase, aldehyde oxidase and/or other unknown enzymes. The microsomal reductase activity was inhibited by oxygen, carbon monoxide, 2-diethylaminoethyl-2,2-diphenylvalerate hydrochloride and n-octylamine, and slightly by cytochrome c; flavin mononucleotide greatly enhanced this activity. 3-Nitrofluoranthene microsomal nitroreductase activity was increased by phenobarbital rat pretreatment and this increment correlated well with the content of cytochrome P450. These results indicate a participation of cytochrome P450 in the reductive metabolism of NFs by rat liver microsomes.

Animals↗
PubMed1989

Characterization of the induction of rat hepatic microsomal drug-metabolizing enzymes by 1-nitropyrene metabolites, 1-aminopyrene and N-acetylaminopyrene.

The effect of 1-aminopyrene (1-AP) and N-acetylaminopyrene (1-NAAP) on rat hepatic microsomal monooxygenase system was investigated. Both drugs increased the total content of cytochrome P-450 (cyt. P-450). The substrate specificity and the electrophoretic pattern of 1-AP and 1-NAAP induced cytochrome(s) were compared with those of the major forms of cyt. P-450 induced by 3-methylcholanthrene (3-MC) and phenobarbital (PB). The results suggest that the form of cyt. P-450 induced by 1-AP and 1-NAAP resembles that one induced by 3-MC. Furthermore the abilities of liver microsomes from control or differently induced rats to ring hydroxylate and to activate 1-nitropyrene (1-NP) metabolites to species mutagenic for bacteria were compared. It was observed that: (1) 1-NAAP is a good substrate for microsome-mediated ring hydroxylation, whereas 1-AP is oxygenated only at a low extent; (2) 3-MC, 1-AP and 1-NAAP-stimulated microsomes are more active than control or PB-ones to ring hydroxylate 1-NAAP. As phenolic derivatives of 1-NAAP show high mutagenic activity, these results indicate that 1-AP and 1-NAAP induce toxification pathways of 1-NP in similar way, even if in less extent, as compared to 3-MC.

Animals↗
PubMed1989

Effect of DNOC, Ferbam and Imidan exposure on mouse sperm morphology.

DNOC, Ferbam and Imidan were tested in (C3H X C57BL/6) F1 mice to assess their potential testicular toxicity. Chemicals were administered i.p. and per os at different doses for 5 consecutive days. After 35 days the testicular was toxicity was evaluated by measuring the testicular weights, the sperm counts and the percentage of abnormal sperm. DNOC and Imidan failed to induce teratospermia in mice treated by both routes of administration. Conversely Ferbam induced a statistically significant increase in teratospermia only following per os administration to mice at a dose of 1000 mg/kg b.w./day. These data indicate that per os administration of Ferbam succeeded in producing active metabolites able to interfere with the differentiation process of spermatogenic cells.

Administration, Oral↗
PubMed1989

Enzymatic acetylation and sulfation of N-hydroxyarylamines in bacteria and rat livers.

In mammalian hepatic cytosol both acetyltransferase and sulfotransferase are involved in the activation of N-hydroxy derivatives of arylamines and arylamides. The role of acetyltransferase is also shown in Salmonella, whereas no rigid evidence is provided on the role of sulfotransferase in Salmonella. In Ames mutagenesis test without S9-mix, the number of revertants of Salmonella typhimurium TA98 induced was 10-fold higher with 2-hydroxyamino-3-methylimidazo[4,5-f] quinoline (N-hydroxy-IQ) than with 2-hydroxyamino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (N-hydroxy-Glu-P-1). The extents of the binding to calf thymus DNA of N-hydroxy-Glu-P-1 were, however, 3.9 to 8.6-fold higher than that of N-hydroxy-IQ in both acetyl CoA- and PAPS-fortified rat hepatic cytosol systems. To understand the mechanism causing the apparent discrepancy between the results of the mutation and DNA binding, the activating capacities of cytosols of S. typhimurium TA98 and TA98/1,8-DNP6 strains on the binding of N-hydroxy-Glu-P-1 and N-hydroxy-IQ have been examined in comparison with those of rat livers. Although both N-hydroxyarylamines were activated by hepatic cytosols in the presence of PAPS, no significant DNA binding of these N-hydroxyarylamines was detected in the presence of PAPS and either one of the two strains of bacterial cytosols. In addition, both cytosols of TA98 and TA98/1,8-DNP6 strains showed no measurable activity on the sulfation of p-nitrophenol, suggesting no capacity for sulfotransferase-mediated activation of N-hydroxyarylamines in Salmonella. On the contrary, the extents of the acetyl CoA-dependent binding of N-hydroxy-IQ in cytosols of TA98, but not of TA98/1,8-DNP6, were respectively 6- and 9-fold higher than those in hepatic cytosols of male and female rats, although the extents of the binding of N-hydroxy-Glu-P-1 were rather higher in hepatic than in bacterial cytosols. In addition, the covalent binding of N-hydroxy-2-acetylaminofluorene to DNA was detected in hepatic, but not in bacterial cytosols, although the binding of N-hydroxy-2-aminofluorene was detectable in both hepatic and bacterial cytosols in the presence of acetyl CoA. These results indicate that the metabolic activating capacities of Salmonella and rat liver cytosols differ qualitatively, and the difference in the substrate specificity of acetyltransferase between Salmonella and rat livers may be involved, in part, in the difference of their DNA damage in bacteria and mammals.

Acetyltransferases↗
PubMed1988

Induction of sperm abnormalities in mice by ifosfamide and trofosfamide.

The antitumor drugs ifosfamide (IF) and trofosfamide (TF) were evaluated for their capability to induce sperm abnormalities in (C3H X C57BL/6)F1 mice. A statistically significant increase in teratospermia was observed at the 35th day after 5 daily consecutive intraperitoneal injections of the drugs at doses of 25, 50, 100 mg/kg b.w. of TF and 100 mg/kg b.w. of IF. Thus, IF and TF are able to interfere with the differentiation process of spermatogenic cells.

Animals↗
PubMed1986

Sublethal pH decrease may cause genetic damage to eukaryotic cell: a study on sea urchins and Salmonella typhimurium.

Further evidence is reported here of genetic and developmental damage that can be induced by a sublethal pH decrease. The effects of three inorganic acids (HCl, H2SO4, and H3PO4) on embryos and sperm from the sea urchins Sphaerechinus granularis and Paracentrotus lividus were evaluated. In addition, acidification of the medium was tested for spontaneous reversion to His+ prototrophy in Salmonella typhimurium (strains TA97, TA98, TA100, TA102, TA1535) up to toxic levels, by both liquid incubation and agar plate incorporation. The induction of developmental and mitotic abnormalities in S. granularis confirmed our previous observations on P. lividus. Embryotoxicity was exerted in S. granularis more severely by H3PO4 than by HCl or H2SO4 (pH 7 to 6), while the induction of mitotic abnormalities appeared at a pH of less than or equal to 6.5 irrespective of the acids used. By suspending S. granularis or P. lividus sperm in acidified filtered seawater (fsw) and then inseminating the eggs in natural fsw (pH = 8.0), the offspring showed developmental and mitotic abnormalities. Low-pH-induced spermiotoxicity was ruled out in our experiments, since fertilization success of acid-exposed sperm was actually enhanced, as compared to sperm suspended in untreated fsw. The exposure of S. typhimurium to different pH's (ranging from 4 to 9) invariably failed to induce any changes in reversion rates, regardless of the acids (or alkali) being used. These results suggest that extracellular acidification may cause sublethal damage that in turn leads to an impairment of mitotic activity and cell differentiation.

Cells↗
PubMed1986

In vitro activation of isophosphamide and trophosphamide to metabolites mutagenic for bacteria.

The ability of S9 liver fractions from uninduced rats to activate isophosphamide (IP) and trophosphamide (TP) to metabolites mutagenic for bacteria was compared to that of S9 fractions prepared from rats pretreated in vivo with three inducers of hepatic monooxygenase. Pretreatment of rats with phenobarbital (PB) and Aroclor 1254 increased IP and TP mutagenic activation by S9 fractions as compared to control and 3-methylcholanthrene (3-MC)-induced rat liver S9. Furthermore, the effect of mixed-function oxidase inhibitors, such as alpha-naphthoflavone, metyrapone and SKF 525-A on S9-mediated mutagenic activation of IP and TP was investigated. The data obtained suggest the involvement of a PB-inducible form of cytochrome P-450 in the activation of IP and TP to mutagenic species.

Animals↗
PubMed1984

[Toxic genetic effects of flunitrazepam].

The mutagenic activity of Flunitrazepam, the active ingredient of the drug Rohypnol, has been investigated by using the Salmonella/microsome mutagenicity test. A dose-related mutagenic effect was observed on Salmonella typhimurium strain TA 100 either in the absence or in the presence of a rat liver microsomal fraction (S9) as in vitro metabolic activation system. By adopting a modification of the Salmonella test, the mutagenicity of urines from rats or patients treated with the drug was evaluated. In these cases mutagenic activity was detected toward the Salmonella strains TA 98 and TA 100 both in presence and in absence of the metabolic activation system. The data indicate that Flunitrazepam and/or its urinary metabolites can induce both base-pair substitutions or frame-shift point mutations.

Animals↗
PubMed1983

Analysis of human urine for mutagens associated with carcinoma of the bilharzial bladder by the Ames Salmonella plate assay.

The Ames Salmonella plate assay was employed to test urine samples from bladder cancer patients and controls living in Egypt for the presence of chemical mutagens. Urine from five groups of Egyptian adults were tested, including individuals with (1) neither bilharziasis nor bladder cancer, (2) urinary bilharziasis and normal urinary cytology, (3) urinary bilharziasis and atypical urinary cytology, (4) carcinoma of the bilharzial bladder, and (5) bladder cancer without bilharziasis. Plates treated with histidine dependent bacteria, S-9 mix, beta-glucuronidases and 0.3 ml sterile urine from all five groups yielded 50 to 150 percent more colonies than plates treated with saline instead of urine. These differences were highly statistically significant for all groups except subjects with bladder cancer without bilharziasis. Gross and microscopic inspection suggested, however, that plates containing urine had heavier bacterial lawns than plates treated with saline. A procedure for quantitating viable bacteria in the lawn was devised which demonstrated that the increase in colonies on urine treated plates could be attributed to increased numbers of viable bacteria in the bacterial lawn on those plates. There was, therefore, no convincing evidence for the presence of mutagenic substances in these urine samples.

Humans↗
PubMed1983

Mutagenicity and DNA damage induced by arylamines in the Salmonella/hepatocyte system.

Coincubation of isolated, intact rat hepatocytes with Salmonella typhimurium tester strain TA 98 (Salmonella/hepatocyte system) has been employed to determine both bacterial mutagenicity and DNA damage in rat hepatocytes following treatment with 2-acetylaminofluorene (AAF) and its derivatives. In vivo pretreatment of rats with either 2,3,7,8-tetrachlorodibenzodioxin or 3-methylcholanthrene markedly increased both DNA damage and bacterial mutation frequency upon incubation of AAF or 2-aminofluorene (AF) in this system. The increase in damage to the hepatocyte DNA was more pronounced after AAF treatment than following AF exposure, while the increase in bacterial mutation frequency was greater after AF treatment. Treatment of hepatocytes with paraoxon prior to exposure to N-hydroxy-2-acetylaminofluorene (N-OH-AAF) or N-acetoxy-2-acetylaminofluorene (N-OAc-AAF) partially inhibited both DNA damage and the bacterial mutagenicity caused by these agents. Treatment of primary rat hepatocytes with 2-hydroxy-2-aminofluorene (N-OH-AF) causes a low level of DNA breaks. Substitution of primary rat hepatocytes with highly differentiated rat hepatoma cells (Reuber H4-II-E) revealed a low level of DNA breakage after exposure to N-OH-AAF whereas treatment with either N-OAc-AAF or N-OH-AF induced a dose dependent increase in DNA breaks. Pretreatment of the Reuber cells with paraoxon inhibited the DNA damage caused by N-OAc-AAF whereas the DNA damage induced by N-OH-AF was increased after paraoxon treatment. Employing host cells with differing metabolic capacity, such as Reuber vs. primary hepatocytes, in the Salmonella/hepatocyte system, may allow a determination of the relative importance of different metabolic pathways in mutagenicity and/or genotoxicity of arylamines.

2-Acetylaminofluorene↗
PubMed1982

[In vivo studies on the transformation of cyclophosphamide to mutagenic metabolites].

Cyclophosphamide (CP), a widely used antineoplastic drug, requires hepatic mixed-function-oxidase-mediated activation to show alkylating activity as well as cytotoxicity, oncogenic transformation and chromosomal aberrations. Evidences are here reported that in vivo activation of CP to urinary mutagenic metabolites is catalyzed primarily by a phenobarbital-inducible cytochrome P-450 system. 24 hours urines from male Sprague-Dawley rats treated i.p. by a single CP administration were filtered through XAD-2 columns and mutagenicity of the acetonic extract was assayed by the Ames test in absence of enzymatic microsomal activation. a highly positive response with a linear dose-dependence was obtained in the range 0.500 mg/kg of CP. Treating rats with Phenobarbital, before CP (500 mg/kg) administration, induced a 250% increase in urine mutagenic activity, whereas. -Naphthoflavone pretreatment reduced the CP activation to urine mutagenic metabolites to 51% as compared with control CP-treated rats.

Animals↗