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Biomedical subjects

G Brambilla

Publications and source records attributed to G Brambilla.

At least 109 records · Page 6Linked to original sources
PubMed1991

DNA fragmentation by 2-nitropropane in rat tissues, and effects of the modulation of biotransformation processes.

The occurrence and persistence of DNA fragmentation, as detected by the alkaline elution technique, have been studied in rats treated with single oral doses of the hepatocarcinogen 2-nitropropane (2-NP). A progressive increase of liver DNA fragmentation was observed at doses ranging from 0.5 to 8 mmol/kg; single strand breaks reached the maximum frequency 6 h after administration, and were partially reduced after 36 h. In contrast, DNA fragmentation was absent in lung, kidney, bone marrow and brain of rats given 8 mmol/kg. The role of cytochrome P-450 in the activation of 2-NP is indicated by the increase of liver DNA damage in rats pretreated with phenobarbital or beta-naphtoflavone, and by its reduction produced by methoxsalen. Both administration of GSH and GSH depletion did not result in clearcut modifications of the genotoxic effect of 2-NP for the liver.

Animals↗
PubMed1991

[Syndrome of the aortic arch and rheumatic polymyalgia. Description of a case].

The paper reports a recently observed case of a 76-year-old man suffering from claudication of the upper limbs, undetectable brachial pressure and bilateral absence of radial, brachial and axillary pulses. During the previous two years the patient had complained of symptoms reminiscent of polymyalgia rheumatica. On admission to hospital, he also presented elevated ESR without temporal arteritic symptoms or involvement of other arterial districts, excluding the main supra-aortic branches, and without ocular signs. Arteriography showed the typical radiological findings of arteritis with bilateral occlusion of the subclavian arteries. Steroid therapy, which was commenced without previous histological biopsy, resulted in a clear subjective and objective improvement in the patient's condition. Following a review of the literature, the A. focus on the incidence of extra-temporal localisations of arteritis associated with polymyalgia rheumatica and on other related problems. They emphasise the importance of beginning steroid therapy as early as possible.

Aged↗
PubMed1991

[Percutaneous treatment of primary varicocele].

40 varicoceles were treated by occlusion of the internal spermatic vein using detachable balloons: the main indications were subfertility and abnormal spermatogenesis. The procedure was successful in 39 patients, with one complication; limited preocclusion venograms allowed precise balloon placement relative to collateral veins which could cause recurrence. This is a safe and effective nonsurgical method of obliterating varicoceles in outpatients.

Adolescent↗
PubMed1990

DNA damage induced in rats by oral administration of chlordiazepoxide plus sodium nitrite or of N-nitrosochlordiazepoxide.

Chlordiazepoxide (CDE) reacts in acidic conditions with NaNO2 yielding N-nitrosochlordiazepoxide (NO-CDE), previously shown to exert genotoxic effects in some in vitro systems. The possible intragastric nitrosation of CDE to NO-CDE has been investigated in rats given by gavage high single doses of this benzodiazepine along with NaNO2. Liver DNA fragmentation, as revealed by both DNA alkaline elution and a more sensitive viscometric method, was found to occur consistently and to be essentially independent of the molar ratio drug/nitrite or of gastric pH. The significant increase in the frequency of DNA lesions observed in rats treated for 15 successive days indicates that DNA repair did not keep pace with the accumulation of the damage. Oral administration of single doses of NO-CDE induced similar dose-dependent amounts of DNA fragmentation in liver, gastric mucosa, and brain. Due to the demonstrated absence of carcinogenic activity in rodents, the present results should be interpreted solely as indicating that NO-CDE is intrinsically capable of producing DNA lesions in vivo, an effect by itself not sufficient to induce tumor growth.

Administration, Oral↗
PubMed1990

Mutation induction in Chinese hamster lung V79 cells by five alk-2-enals produced by lipid peroxidation.

Five alk-2-enals--pent-2-enal, hex-2-enal, hept-2-enal, oct-2-enal and non-2-enal--produced by lipid peroxidation were tested for mutagenic activity in V79 Chinese hamster cells. At concentrations ranging from 0.003 to 0.3 mM all 5 alk-2-enals induced a dose-dependent increase in the frequency of 6-thioguanine-resistant mutants, and their mutagenic potency was found to increase with the length of the carbon chain. In contrast, only hept-2-enal produced a statistically significant increase in the number of mutations to ouabain resistance.

Aldehydes↗
PubMed1990

Comparison of the sensitivity of human and rat hepatocytes to the genotoxic effects of metronidazole.

Metronidazole (MNZ), an antiprotozoan and antibacterial agent, has been shown to yield DNA-damaging reactive species after nitroreductive biotransformation. The genotoxic effect of MNZ was studied in primary cultures of both rat and human hepatocytes. In millimolar concentrations MNZ produced DNA fragmentation, as measured by the alkaline elution technique, and unscheduled DNA synthesis, as evaluated by quantitative autoradiography, in rat hepatocytes. The amount of DNA damage was directly related to the dose and the length of exposure, was increased by hypoxia and GSH depletion, and was markedly reduced by inhibition of cytochrome P-450 activity. In the same experimental conditions human hepatocytes resulted constantly more resistant than rat hepatocytes to the genotoxic activity of MNZ. These findings suggest that the rat hepatocyte model might be an inappropriate predictor of nitroimidazoles genotoxicity.

Adult↗
PubMed1989

Genotoxicity of N-nitrosochlordiazepoxide in cultured mammalian cells.

Chlordiazepoxide, a benzodiazepine derivative commonly used for the treatment of anxiety, was found to react with sodium nitrite in HCl aqueous solution yielding, at pH ranging from 0.5 to 5,N-nitrosochlordiazepoxide (NO-CDE). In the absence of a metabolic activation system, a dose-dependent frequency of DNA single-strand breaks was revealed by the alkaline elution technique in V79 cells exposed to subtoxic NO-CDE concentrations ranging from 33 to 330 microM. DNA lesions were only partially repaired within 48 hr, and their promutagenic character was demonstrated by the induction of 6-thioguanine resistance in the same cells. The genotoxicity of NO-CDE was confirmed by results obtained in metabolically competent primary cultures of both rat and human hepatocytes, which displayed similar dose-related amounts of DNA fragmentation and of DNA repair synthesis after treatment with concentrations ranging from 33 to 1000 microM. In conclusions similar to those which might occur in the stomach of a patient taking chlordiazepoxide the concentration of NO-CDE in the reaction mixture (50 microM) was of the same order as the concentrations found to induce a genotoxic effect in cultured mammalian cells.

Animals↗
PubMed1989

Comparison of DNA alkylation, fragmentation, and repair in maternal and fetal tissues of pregnant rats treated with a single dose of ethyl methanesulfonate, ethyl-N-nitrosourea, N-nitrosodiethylamine, and methyl-N-nitrosourea.

The occurrence and persistence of DNA damage, as detected by the alkaline elution technique, have been studied in some tissues of both fetal and adult Sprague-Dawley rats (18th day of gestation) after administration of a single equimolar dose (0.5 mmol/kg) of ethyl methanesulfonate (EMS), N-ethyl-N-nitrosourea (ENU), N-nitrosodiethylamine (NDEA), and N-methyl-N-nitrosourea (MNU). EMS, ENU, and MNU, injected intravenously, produced a statistically significant increase of DNA elution rate, which is considered indicative of DNA fragmentation, in both maternal and fetal liver, kidney, and brain. NDEA, introduced by gastric gavage, induced DNA breaks in both liver and kidney of dams, but only in the liver of fetuses. The frequency of DNA lesions was found to vary with the four alkylating agents and in the three organs tested, to exhibit a different time course, and usually to be higher in maternal than in fetal tissues. Results provided by the concomitant determination of DNA binding levels demonstrated a satisfactory correlation with the amounts of DNA fragmentation. In contrast, the values of both these parameters did not show any positive correlation with the different susceptibility of the three organs to tumor induction. In conclusion, these findings suggest that when a compound is not available in radiolabeled form, measurement of DNA fragmentation may represent a useful alternative to the determination of DNA binding level in order to obtain information on the distribution of its reactive species in maternal and fetal tissues.

Alkylating Agents↗
PubMed1989

Is lipid peroxidation associated with DNA damage?

Specific binding to DNA of lipid peroxidation products was studied in rat hepatocytes labeled with [14C(U)]arachidonic acid after incubation at 37 degrees C either in the absence or in the presence of 200 microM FeSO4. The results obtained show that: (1) production of malondialdehyde-like thiobarbituric-reactive substances occurred in the absence of FeSO4 and was increased, albeit quite variably, by exposure to this pro-oxidant; (2) a low but appreciable binding of radioactivity to DNA and protein was constantly detected in 5 independent experiments; (3) there was no quantitative correlation between malondialdehyde formation and the amount of DNA-bound and protein-bound radioactivity, and any meaningful evidence of a GSH-depletion effect was absent. Taking into account the possible biosynthetic incorporation of radioactivity into DNA, the results of this study must be interpreted with caution, and solely as indicating that in the intact cell the covalent binding to DNA of reactive species generated by lipid peroxidation, if it occurs, should be minimal, corresponding in our experimental conditions approximately to 0.01 mumole of radioactive arachidonic acid per mole nucleotides.

Animals↗
PubMed1989

Absence of liver DNA fragmentation in rats treated with high oral doses of 32 benzodiazepine drugs.

Literature data on mutagenic-carcinogenic activity of benzodiazepines are scarce, restricted to few of them, and contradictory. Consequently, in order to provide additional information for the assessment of the genotoxic risk connected with the use of this family of drugs, 32 benzodiazepines of various chemical structure have been tested for their capability to induce DNA damage in vivo, which is considered a sensitive index of potential mutagenic-carcinogenic activity. The frequency of DNA single-strand breaks and/or alkali-labile sites was checked in the liver of rats given orally a single dose (1 mmol/kg) or 15 successive daily doses (0.2 mmol/kg) by the use of a new viscometric technique capable of detecting one DNA lesion per 10(10) Da. Statistically significant changes of viscometric parameters indicative of liver DNA fragmentation were absent with all 32 benzodiazepines, after both acute and subacute treatments. Since the doses tested in rats were from 100 to more than 5000 times higher than doses usually administered to humans, these negative results are in favor of the absence of mutagenic-carcinogenic effects in patients taking benzodiazepines.

Animals↗
PubMed1989

Mutagenicity in V79 Chinese hamster cells of n-alkanals produced by lipid peroxidation.

The mutagenicity for mammalian cells of five n-alkanals produced by lipid peroxidation was tested in V79 Chinese hamster lung cells either at the hypoxanthine-guanine phosphoribosyltransferase locus as resistance to 6-thioguanine or at the Na/K ATPase locus as resistance to ouabain. The results show that propanal, butanal, pentanal and hexanal induced a dose-dependent increase in the frequency over controls of both 6-thioguanine- and ouabain-resistant mutants at concentrations ranging from 3 to 30 mM. With nonanal the same effects were observed with concentrations of 0.1-0.3 mM.

Aldehydes↗
PubMed1988

Comparative study of DNA damage and repair induced by ten N-nitroso compounds in primary cultures of human and rat hepatocytes.

Ten carcinogenic N-nitroso compounds were assayed for DNA-damaging activity in primary cultures of human and rat hepatocytes. DNA fragmentation was measured by the alkaline elution technique, and unscheduled DNA synthesis by quantitative autoradiography. Positive dose-related responses in the range of subtoxic concentrations indicated were obtained in cells of both species with N-nitrosodiethylamine (10-32 mM), N-nitrosodi-n-propylamine (1.8-10 mM), N-nitrosomorpholine (1-3.2 mM), N-nitrosopiperidine (1-3.2 mM), N-nitrosopyrrolidine (3.2-18 mM), N-nitroso-N-methylurea (0.32-1.8 mM), N-nitroso-N-ethylurea (0.32-1.8 mM), and N-nitroso-N-butylurea (0.1-0.32 mM). N-nitrosodi-n-butylamine was practically inactive at the maximal soluble concentration (1 mM). The responses of human hepatocytes were qualitatively similar to those of rat hepatocytes, but statistically significant differences between the two species in the amounts of DNA damage and/or unscheduled DNA synthesis were observed with N-nitrosodimethylamine, N-nitrosomorpholine, N-nitrosopiperidine, N-nitrosopyrrolidine, and N-nitroso-N-butylurea. On the other hand, quantitative differences in the genotoxic effects induced by 5 mM N-nitrosodimethylamine in cultures derived from 20 human donors and from 20 rats were greater than average interspecies differences displayed by this nitrosamine and by other N-nitroso compounds. These results indicate that the rat hepatocyte DNA repair assay is a valid model for predicting the genotoxic potential of N-nitroso compounds in human hepatocytes.

Adult↗
PubMed1988

Cardiac transplantation in Becker muscular dystrophy.

A 23-year-old man with X-linked Becker type muscular dystrophy underwent cardiac transplantation because of dilated cardiomyopathy which was complicated by terminal heart failure. Impairment of muscle function was mild and slowly progressive, whereas the cardiac disease was severe and rapidly progressive. All four chambers of the removed heart were grossly dilated; microscopically, the myocardial fibres were hypertrophic and pale; the nuclei exhibited pleomorphism with variability in nuclear size, shape, and depth of staining.

Adult↗