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Biomedical subjects

G Bronzetti

Publications and source records attributed to G Bronzetti.

At least 37 records · Page 2Linked to original sources
PubMed1996

Antimutagenesis and anticancer effects.

Cancer development is a multistage process wherein mutational events play an important role. Various antimutagen components, in particular magnesium and selenium, have been reported to have anticarcinogenic properties. These two oligoelements display different behaviors according to their concentrations. The different effects of magnesium and selenium depend on the different mechanisms of cell absorption. The importance of antimutagenesis studies in cancer prevention is reported and a review of the basic mechanisms operative in antimutagenesis, including some data on known antimutagens, is made.

Animals↗
PubMed1995

Effect of magnetic fields on rodent monooxygenase enzymes.

The effects of 50 Hz, 1.2 mT magnetic fields (MFs) were tested on hepatic monooxygenase enzymes of basal and beta-naphthoflavone-phenobarbital-preinduced rats and mice. An inductive effect on cytochrome P-450 level and on some enzymatic cytochrome P-450-dependent activities was observed in basal mice after MF exposure. Enzymatic activities in preinduced mice and rats were reduced by MFs, the degree of reduction depending on the enzyme. A specific inhibitory effect was determined in some of the assayed activities and in the relative peculiar P-450 isoforms detected by Western blot analysis.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1995

[Transvenous cardioverter-defibrillators: clinical experience at implantation and follow-up].

Thirty-seven patients with ventricular tachyarrhythmias refractory to antiarrhythmic drug treatment, guided by electrophysiological testing, were submitted to implantation of a cardioverter-defibrillator by the transvenous technique. Mean age was 55 +/- 14 years and the underlying heart disease was coronary heart disease in 24 patients, cardiomyopathy or other etiologies in 11 patients. In 2 patients ventricular arrhythmias were idiopathic. Left ventricular ejection fraction was < or equal to 40% in 65% of the patients. The following devices were implanted: CPI Ventak P in 2 patients, Ventak P2 in 9 patients, Ventak PRx in 9 patients, Ventak PRxII in 2 patients, Telectronics Guardian ATP III 4215 in 9 patients, Siemens Siecure in 5 patients, Medtronic Jewel PCD in 1 patient. At implantation defibrillation threshold was lower with biphasic shocks than with monophasic shocks (17.0 +/- 3.2 vs 20.9 +/- 3.8 J, p < 0.003) and the need for subcutaneous patches was lower when biphasic shocks were employed. Operative and perioperative mortality were 0% and no significant complications were observed. During the follow-up (16 +/- 11 months) 35% of the patients had appropriate shocks and 93% of the patients with antitachycardia pacing availability (n = 15) had effective antitachycardia pacing interventions. The following complications were observed: lead failure in 4 patients (3 insulation breaks and 1 elongation for stretching), late lead dislodgement in 2 patients, lead recall in 1 patient, all of which required reintervention. Inappropriate shocks occurred in 30% of the patients and were related to lead failure, supraventricular arrhythmias or alternating current interference. During the follow-up one patient died of sudden death and one was submitted to heart transplantation. In conclusion, implantation of a cardioverter-defibrillator by the transvenous technique is a procedure relatively free from complications. During the follow-up lead failure appears to be one of the most relevant complications. Antitachycardia pacing allows effective termination of ventricular tachycardias without cardioversion, with a better compliance.

Adult↗
PubMed1995

Magnesium: its role in cellular functions--a review.

Magnesium has been identified as an important element in cellular functions, and its abnormalities have far-reaching effects in pathology. We reviewed its effects in the cell cycle, its physiological role, nutritional aspects, toxicity, mutagenesis, and tumorigenesis.

Anticarcinogenic Agents↗
PubMed1994

Effects of spermine on formation of HGPRT- mutants induced by ethylmethanesulfonate, methylmethanesulfonate, and mitomycin C in V79 Chinese hamster cells.

Spermine is a polyamine found in bacteria, animal, and plant tissues. It is involved in a variety of biological processes, and its interaction with DNA stabilizes the secondary structure of the double helix. Spermine is one of the first reported antimutagens, reducing the mutation rate in several prokaryotic test systems, while in eukaryotic organisms conflicting results have been obtained. In light of the significant antimutagenic effect of spermine, it is important to evaluate its activity in mammalian cells in culture. The present study was undertaken to evaluate the ability of spermine to suppress the level of HGPRT- mutants induced by ethylmethanesulfonate, methylmethanesulfonate, and mitomycin C. Spermine reduced the mutation frequency induced by ethylmethanesulfonate and methylmethanesulfonate but did not affect survival; with mitomycin C survival was reduced but mutation rate was not influenced.

Alkylation↗
PubMed1994

Effects of cinnamaldehyde on survival and formation of HGPRT- mutants in V79 cells treated with methyl methanesulfonate, N-nitroso-N-methylurea, ethyl methanesulfonate and UV light.

The effects of the antimutagenic flavoring cinnamaldehyde on the induction of HGPRT- mutants by methyl methanesulfonate (MMS), N-nitroso-N-methylurea (MNU), ethyl methanesulfonate (EMS) and UV light was investigated in the Chinese hamster V79 cell line. Cinnamaldehyde did not show any mutagenic or toxic effects in this experimental system by itself and did not modify mutation frequency when given to cells simultaneously with chemical mutagens. Under these conditions, the cytotoxicity of MMS, but not that of MNU and EMS, was increased. Cell viability was also reduced in MNU-, EMS-, or UV light-pretreated cells when they were postincubated in the presence of cinnamaldehyde. Moreover, cinnamaldehyde reduced the frequency of mutations induced by MMS but not by the other mutagens. The results obtained suggest that cinnamaldehyde inhibits some cellular function(s) promoting the repair of a variety of different cytotoxic lesions. At the same time, stimulation by cinnamaldehyde of an error-free DNA repair mechanism acting on MMS-induced mutagenic damage was indicated.

Acrolein↗
PubMed1994

Induction of cytochrome P-450 by 5-methoxypsoralen in the yeast Saccharomyces cerevisiae.

Yeast cells (D7 strain) incubated in the presence of 5-methoxypsoralen (5-MOP) increase the activity of the monooxygenase system cytochrome P-450 dependent (cytochrome P-450 level and 7-ethoxycoumarin-O-diethylase activity). Northern analysis of cytochrome P-450 specific RNA shows that 5-MOP treatments induce an increase in mRNA. The induction of cytochrome P-450 appears to occur at the transcriptional level. The capacity of 5-MOP to induce the cytochrome P-450 system in eukaryotic cells, in which it is known to be involved in the metabolism of the psoralen, may decrease the availability of the compound for photo-induced genotoxic reactions, which may explain the good tolerance in patients.

5-Methoxypsoralen↗
PubMed1993

Inhibition of yeast cytochrome P-450 by ammonium metavanadate.

Incubation of diploid D7 strain cells of Saccharomyces cerevisiae (grown in 20% glucose) in the presence of ammonium metavanadate (AMV) led to a decrease in the cytochrome P-450-dependent monooxygenase system (cytochrome P-450 level and 7-ethoxycoumarin O-deethylase). The electrophoretic analysis of microsomal fractions of yeast cells treated with metavanadate revealed a decrease in the intensity of the bands corresponding to a M(r) in the range of 51,000-58,000 Da compared with those observed in controls, i.e., cells grown in 20% glucose. Analysis of the cytochrome P-450 transcript showed that AMV treatment reduced the mRNA level. Our results suggest that AMV inhibits the yeast cytochrome P-450 system by acting at both the pre- and post-transcriptional levels.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1993

Genotoxic and biochemical effects of dimethylamine.

The genotoxicity of dimethylamine (DMA) was investigated in the D7 strain of Saccharomyces cerevisiae. DMA was able to induce mitotic gene conversion and point reverse mutation in the presence of metabolic activation (S9 fraction). To study the co-mutagenicity/co-carcinogenicity or toxicity of DMA, changes in xenobiotic metabolizing enzymes were studied in purified microsomes from DMA-induced mice or rats receiving a single or three consecutive doses (25 or 50 mg/kg body wt). Pentoxyresorufin O-dealkylase (class IIB1 P450, PROD), ethoxyresorufin O-deethylase (IA1, EROD) and p-nitrophenol hydroxylase (IIE1, pNPH) were all affected by DMA treatment with a loss of activity of 62, 55 and 54% in the mouse, or 64, 25 and 56% in the rat for PROD, EROD and pNPH activities, respectively, at the highest tested dose. No significant alteration of P450 IIIA-like activity was seen. Results indicated that the metabolites of DMA induced genetic activity in yeast. In addition, a clear non-specific hepatotoxic effect was recorded as a significant reduction in activity of the selected monooxygenases.

Animals↗
PubMed1992

Antimutagenicity in yeast.

In recent years there has been increasing interest in antimutagenesis, and studies have been done using both prokaryotic and eukaryotic systems. In eukaryotic systems the first studies were performed with different strains of Schizosaccharomyces pombe. In particular, caffeine and L-methionine were investigated. Different strains of Saccharomyces cerevisiae were employed in studies of a wide variety of compounds, including acridine, saccharin, salts, tumor promoters and co-carcinogens. Strain D7 was widely employed and antimutagenic activity of spermine, chlorophyllin, cobaltous chloride and fermented milk is reported.

Animals↗
PubMed1992

Influence of cinnamaldehyde on UV-induced gene conversion and point mutation in yeast: effect on protein synthesis.

The activity of cinnamaldehyde (CIN), a bioantimutagen in bacterial systems, was tested in the D7 strain of yeast Saccharomyces cerevisiae. Yeast cells were UV-irradiated and post-incubated in liquid growth medium for 2 and 4 h with different concentrations of cinnamaldehyde. During the post-incubation period, DNA-damage-specific functions may be induced. This in turn may affect the genotoxicity and in fact a weak decrease in UV-induced convertant and revertant frequencies was observed after 4 h of post-incubation. The presence of CIN in the growth medium increased the UV-induced gene conversion and reversion. The addition of cycloheximide abolished this effect. To evaluate the CIN effect on protein synthesis, extracts of cells UV-treated and post-incubated for 2 h in the presence of 35S-methionine were performed. SDS-gel electrophoresis demonstrated the inhibitory effect of CIN on a UV-specific protein. This work suggests that CIN might interfere with DNA-damage-inducible systems although it did not exert an antimutagenic activity in our experimental conditions.

Acrolein↗
PubMed1992

Mutagenicity of methyl methanesulfonate and cyclophosphamide in resting and growing Saccharomyces cerevisiae D7 cells.

In order to evaluate the optimal experimental conditions and to identify the best growth phase for yeast genotoxicity studies, comparative experiments were performed with stationary and growing cells. Methyl methanesulfonate (MMS) and cyclophosphamide (CP) were used as chemical mutagens and strain D7 of Saccharomyces cerevisiae as detector of induced mitotic gene conversion (trp+ convertants) and point reverse mutation (ilv+ revertants) in log or stationary phase cells after either 4 or 16 h of treatment. The highest MMS-induced toxicity and genotoxicity were observed after 16 h of exposure in a suspension test with log phase cells, which is consistent with the greater permeability and sensitivity of growing yeast cells. The maximal induction of genetic effects and toxicity by CP was conversely obtained after 16 h of treatment in stationary phase cells. This may be ascribed to the greater ability of detoxication of growing cells as compared to resting cells. Our results suggest that in evaluating the mutagenicity of chemicals in yeast systems it is important to consider factors such as growth phase and exposure time.

Cyclophosphamide↗
PubMed1992

Expression of cytochrome P450 in yeast after different chemical treatments.

In Saccharomyces cerevisiae a number of chemical agents induce synthesis of cytochrome P450. A cytochrome P450 gene has been well characterized in this yeast: CYP51, which codes for a constitutive enzyme involved in the 14 alpha-demethylation of lanosterol, a key step in the biosynthesis of ergosterol. In this work, we have analysed the level of transcription of the CYP51 gene in correlation with cytochrome P450 enzymatic activity after treatment with several chemical agents known to interact with cytochrome P450. Using as a probe a DNA fragment whose identity to the CYP51 gene was established by sequence analysis and mapping on chromosome VIII, a unique RNA species was observed in all treatment samples. The increased level found for this transcript in cells treated with ethanol, 20% glucose, phenobarbital or 5-methoxypsoralen correlates with the levels of induction in cytochrome P450 enzymatic activity measured in cells grown under the same conditions, indicating that induction of cytochrome P450 by these treatments is regulated at the transcriptional level.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1991

Genotoxicity of vanadium compounds in yeast and cultured mammalian cells.

The ability of vanadium compounds to induce genetic activity was investigated in D7 and D61M strains of Saccharomyces cerevisiae and in Chinese hamster V79 cell line. In our previous work, ammonium metavanadate (pentavalent form, V5) induced mitotic gene conversion and point reverse mutation in the D7 strain of yeast. The genotoxicity was reduced by the presence of S9 fraction, which probably reduced pentavalent vanadium to the tetravalent form. In the present study, vanadyl sulfate (tetravalent form, V4) induced no convertants and revertants in yeast cells harvested from stationary growth phase. With yeast cells from logarithmic growth phase, which contain high levels of cytochrome P-450, a significant increase in genetic effects was observed. Further experiments, performed by treating cells harvested from logarithmic growth phase in the presence of cytochrome P-450 inhibitors, indicated that the monooxygenase system influenced the genotoxicity of metavanadate while the genetic activity of vanadyl remained unaffected. Aneuploidy effect in the D61M strain of Saccharomyces cerevisiae was induced by either V5 or V4, confirming that vanadium compounds are potentially antitubulin agents in eukaryotic cells. Although these compounds are very toxic in V79 cells, no mutagenic effect was observed in the presence or in the absence of S9 fraction.

Animals↗