Biomedical subjects

L Zentilin

Publications and source records attributed to L Zentilin.

25 records · Page 2Linked to original sources

PubMed1990

Serotype 3 human rotavirus strains with subgroup I specificity.

During an epidemiological study on human rotavirus (HRV) infections in Italy, three subgroup I strains not associated with serotype 2 reactivity were detected. All three strains were serotype 3, each with a distinct RNA pattern showing fast-moving tenth and eleventh segments (long electropherotype). Following successful adaptation to growth in cell cultures, the serotype 3 strains (MZ58, PCP5, and PA710) were further characterized by neutralization and by RNA-RNA (Northern blot) hybridization. Antiserum to reference HRV strain YO (subgroup II, serotype 3), as well as a monoclonal antibody to VP7 of YO neutralized, at comparable titers, the homologous virus, the three unusual HRV strains, and two reference simian strains (SA11 and RRV-2, both subgroup I, serotype 3), whereas SA11 antiserum and a monoclonal antibody to VP7 of SA11 neutralized simian strains more efficiently. However, antiserum to PCP5 neutralized the three unusual isolates and the simian strains at significantly higher titers than it did with reference strain YO. With 32P-labeled RNA from MZ58 as a probe, a high degree of homology was detected by Northern blot hybridization with strains PCP5, PA710, SA11, and UK (bovine rotavirus) at the level of several segments and with strain YO only at the level of genes 7 to 9. Conversely, labeled RNA of strain YO hybridized extensively with Wa (subgroup II, serotype 1 HRV strain) but only at the level of genes 7 to 9 with MZ58, PCP5, PA710, SA11, and UK. Finally, the labeled SA11 probe hybridized at the level of RNA segments 1 to 3 and 6 to 11 to the three unusual strains. These findings suggest that the unusual subgroup I, serotype 3, strains isolated from humans are more likely to be animal rotaviruses rather than natural reassortants between different HRV strains.

Blotting, Northern↗

PubMed1989

A recombinant hepatitis B core antigen polypeptide with the protamine-like domain deleted self-assembles into capsid particles but fails to bind nucleic acids.

We have cloned in Escherichia coli both the complete core gene of hepatitis B virus and a truncated version of it, leading to the synthesis of high levels of a core-antigen-equivalent polypeptide (r-p22) and of an e-antigen-equivalent polypeptide (r-p16), respectively. We then compared the structural and antigenic properties of the two polypeptides, as well as their ability to bind viral nucleic acids. r-p16 was found to self-assemble into capsid-like particles that appeared similar, when observed under the electron microscope, to those formed by r-p22. In r-p16 particles, disulfide bonds linked the truncated polypeptides in dimers, assembled in the particle by noncovalent interactions. In r-p22 capsids, further disulfide bonds, conceivably involving the carboxy-terminal cysteines of r-p22 polypeptides, joined the dimers together, converting the structure into a covalently closed lattice. The protamine-like domain was at least partly exposed on the surface of r-p22 particles, since it was accessible to selective proteolysis. Finally, r-p22, but not r-p16, was shown to bind native and denatured DNA as well as RNA. Taken together, these results suggest that the protamine-like domain in core polypeptides is a nucleic acid-binding domain and is dispensable for the correct folding and assembly of amino-terminal and central regions.

Capsid↗

PubMed1987

Solubilization by nitrilotriacetic acid (NTA) of genetically active Cr(VI) and Pb(II) from insoluble metal compounds.

The frequencies of sister chromatid exchanges (SCE) were significantly increased in cultured Chinese hamster cells by insoluble salts of Cr(VI) (PbCrO4) and Pb(II) (PbSO4). A further significant increase of this effect was produced when diluted suspensions of PbCrO4 (1-4 mg/l) and PbSO4 (10-40 mg/l) were preincubated with nitrilotriacetic acid (NTA) concentrations (0.25-1 mg/l) such as those that are possibly found in highly contaminated environmental situations. NTA enhanced the induction of SCE by PbCrO4 and PbSO4 even in the presence, in the preincubation solution and in the medium used to treat the cells, of Na+ and K+ concentrations largely exceeding (e.g., 10(2)-10(6) times) those of the genotoxic metals.

Acetates↗

PubMed1985

Interaction of nitrilotriacetic acid with heavy metals in the induction of sister chromatid exchanges in cultured mammalian cells.

The ability of nitrilotriacetic acid trisodium salt (NTA) to induce sister chromatid exchanges (SCE) and to influence the induction of SCE by heavy metal compounds was evaluated with mammalian cell cultures. In accordance with the generally negative results obtained by other investigators on the mutagenic effects of NTA, no increase of SCE frequency was observed in Chinese hamster cells (CHO line) or in primary cultures of mouse (BALB/c and BALB/Mo strains) lymphocytes, after treatment with NTA at subtoxic concentrations (2 X 10(-3) M and 10(-3) M, respectively). The induction of SCE by salts of heavy metals (Cd, Hg, Ni, Pb) was evaluated with CHO cells. Soluble (CdCl2, HgCl2, NiCl2, Pb [CH3COO]2) and insoluble (CdCO3, HgCl, NiCO3, PbSO4) compounds were tested, and, with the exception of Pb(CH3COO)2, all were found to increase the frequency of SCE. NTA apparently did not affect the ability of the soluble metal compounds to induce SCE, but it significantly increased the frequency of SCE induced by treatment with all the insoluble salts.

Acetates↗

PubMed1985

Effects of nitrilotriacetic acid on the induction of gene mutations and sister-chromatid exchanges by insoluble chromium compounds.

The influence of nitrilotriacetic acid trisodium salt (NTA) on the mutagenic and clastogenic activity of several water-insoluble or poorly soluble chromium compounds was determined by means of the Salmonella/microsome assay (plate test on TA100 strain) and the sister-chromatid exchange (SCE) test in mammalian cell cultures (CHO line). NTA in itself did not induce gene mutations nor did it increase the frequency of SCE. Cr(VI) compounds (Pb, Ba, Zn, Sr and Ca chromates) and an industrial Cr(VI) pigment, chromium orange (containing PbCrO4 PbO), were inactive or scarcely active mutagens in the Salmonella/microsome test when dissolved in water, but they were increasingly mutagenic when solubilized by 0.5 N NaOH or NTA (10 or 100 mg/ml). Also, the mutagenic activity of Cr(VI), contaminating an industrial Cr(III) pigment (chromite), was slightly enhanced by NTA. Mutagenicity of chromates was correlated with the amounts of Cr(VI) solubilized by NTA or alkali, as determined by the colorimetric reaction with diphenylcarbazide and atomic absorption spectrophotometry, and was decreased by incubation with microsomes, due to reduction of Cr(VI) to the genetically inactive Cr(III) form. In the SCE assay, the insoluble or poorly soluble Ba, Zn, Sr and Ca chromates and the insoluble Cr(VI) pigments zinc yellow (containing ZnCrO4 Zn(OH2], chromium yellow and molybdenum orange (both containing PbCrO4) were directly clastogenic due to cellular endocytosis taking place in prolonged treatments, and NTA significantly increased their chromosome-damaging activity.

Acetates↗

PubMed1985

Genetic effects of chromium tannins.

Seventeen tannins used in the hide and leather industry, most of which contain mainly Cr(III) sulphates, were tested for the ability to directly induce gene mutations in Salmonella typhimurium (TA 100 strain) and chromosomal effects (sister chromatid exchanges, SCE) in cultured hamster cells (CHO line). Total chromium [Cr(III) + Cr(VI)] content and contaminating Cr(VI) were determined spectrophotometrically by reaction with diphenylcarbazide. None of the tested compounds induced gene mutations, whereas eight tannins were able to increase significantly the frequency of SCE. A contamination with Cr(VI) was detected in four compounds (from 30 up to 100 parts of Cr(VI) per 10(6) parts of compound), insufficient to be revealed by the Salmonella assay but sufficient to account for the observed SCE increase. On the other hand, the increase of SCE induced by the other four tannins could not be explained by the level of Cr(VI) contamination, and can be ascribed to other impurities present in those industrial compounds. These four tannins did not induce gene mutations in the S. typhimurium assay even when strain TA 98 was used in addition to TA 100, independently of microsomal activation. By prolonging the time of the SCE assay from 30 to 48 h in order to facilitate Cr(III) endocytosis, a significant increase of the SCE frequency was induced by an analytical-grade Cr(III) reagent (chromium chloride), absolutely uncontaminated by Cr(VI), as well as by three Cr(III) tannins, otherwise inactive in the SCE assay.

Animals↗

PubMedDate not supplied

Image analysis in quantitative PCR. An application for the measurement of c-erbB-2 oncogene amplification in DNA from human tumours.

We present an application of image analysis for the direct quantification of PCR products after gel electrophoresis and ethidium bromide staining of DNA. This procedure has been applied to the development of an assay based on competitive PCR for the measurement of the degree of amplification of c-erbB-2 oncogene in DNA from human tumours. In this method two DNA species (genomic and competitor) compete for PCR amplification. Since results are calculated from the final competitor/genomic ratio any variable affecting the rate of PCR amplification has no effect on the accuracy of the ratio measurement. Results are reported which show that even large variations in the experimental conditions (number of PCR cycles, sample volumes and extracted DNA quality) did not interfere with the precision of the measurement of the competitor/genomic ratio.

Binding, Competitive↗