Investigations on the detection of mutagenic activity of beef extract in rats after oral administration.

After oral administration of beef extract the body fluids of Aroclor-treated and untreated rats were investigated for mutagenicity using the Salmonella/microsome test. In the stomach contents, the bile and the urine of the animals, mutagenic activity was discovered after S-9 activation. Although the mutagenic substances must have been transported by the blood stream to the excreting organs no increased mutagen-induced his+ revertants were observed in venous blood. Direct-acting mutagens were not detected in the tested body fluids, either in the Aroclor-treated rats or in the untreated ones.

Binding of chemical carcinogens and mutagens to rat hemoglobin.

The alkylation of hemoglobin is a proposed dose monitor for chemical carcinogens and mutagens. The binding of fifteen chemical carcinogens and mutagens to rat hemoglobin was determined. Direct acting carcinogens and indirect acting carcinogens including aromatic amines, halogenated hydrocarbons, nitrosamines, polycyclic aromatic hydrocarbons, aflatoxin B1 and benzene bound hemoglobin. The efficiency of carcinogen and mutagen hemoglobin was dose dependent and ranged from 0.007 to 2.3% of an oral dose. The binding of chemical carcinogens and mutagens to hemoglobin would appear to be generic so that it could be developed into a dose monitor for a large number of known carcinogens and mutagens.

Mutagenic activity of metabolites contained in the plasma of Sprague-Dawley rats treated with cyclophosphamide.

In the present study we have tried to add some new results to those data previously obtained by Natarajan et al. (1983) and Darroudi and Natarajan (1985), where they have used in vivo metabolization and cytogenetic testing for in vitro analysis of xenobiotic compounds. Sprague-Dawley rats were treated intraperitoneally with 2.5, 5.0, 10.0 and 20.0 mg/kg b.w. of cyclophosphamide in order to obtain plasma containing active metabolites of the drug. The mutagenic activity was assessed by estimating the frequencies of sister-chromatid exchanges (SCE) in human and rat lymphocytes. No influence of animal age was observed on the metabolism of cyclophosphamide, which could be detected by SCE analysis. The increase in SCE frequencies in both human and rat lymphocytes was dependent on the doses applied. SCE frequencies are highly variable among individuals, showing statistically significant differences. The same effect, but to a lesser extent, was also found in rats. Rat lymphocytes can be assumed to be good biological material for chemical mutagenesis, as the animals can be maintained at almost constant experimental conditions. However, rat lymphocytes do not grow well in in vitro cultures. These data contribute to the preview proposal that combining metabolism in vivo and chromosome SCE analysis in vitro can be regarded as an important and very sensitive system to detect the mutagenic activity of low-dose exposure to chemical compounds requiring metabolic activation.

In vitro and in vivo mutagenicity studies with airborne particulate extracts.

The contribution of nitro compounds to airborne particulate mutagenicity was studied with Salmonella typhimurium strains TA98, TA98NR, TA98/1,8DNP6. The results obtained indicate that nitropyrenes play a minor role in air particulate mutagenicity. Seasonal variations indicate a relatively greater contribution of nitro compounds to the mutagenicity of spring and summer samples. Fractionation of extracts into acidic, neutral and basic components shows that neutral compounds account for about two-thirds of the total mutagenic activity. Attempts to extract mutagens adsorbed onto particulate matter with aqueous media were almost completely negative. No significant mutagenicity was detected in urine and faecal extracts and in plasma samples of Sprague-Dawley rats treated with air particulate extracts at 80 mg/kg either per os or by i.p. injection. Negative results were obtained in the micronucleus test with Swiss mice treated at 200 and 400 mg/kg (twice by i.p. injection). A significant decrease in liver aminopyrine-N-demethylase was observed in Swiss mice injected with air particulate extracts or its basic and neutral fractions. In vitro experiments suggest a direct interaction of test materials with microsomal cytochrome P-450.

Components of paint thinner in body fluids clearly detected using the salting-out technique.

For a more sensitive detection of paint thinner components in body fluids, we made use of a salting-out technique, with sodium chloride added to blood samples followed by gas chromatography, using the headspace method. The detection of ethyl acetate and isobutanol was considerably enhanced using these approaches.

The pathogenesis of systemic lupus erythematosus.

Many investigators believe that systemic lupus erythematosus is an autoimmune disease, perhaps caused by inadequate suppressor T lymphocyte activity, which permits the activation of autoantibody producing B lymphocytes. This paper discusses the testable hypothesis that a superoxide-generating, chromosome aberration-inducing factor (clastogenic factor), present in the lymphocytes of lupus patients but absent from normals, is responsible for such a suppressor cell defect. Superoxide or activated oxygen species derived from it, such as hydroxyl radical, may be the molecular mediators of CF activity.

Some pharmacokinetic data on miocamycin. I: Serum, urinary and prostatic levels.

The pharmacokinetics of miocamycin were studied in ten healthy male volunteers after three different administrations: the first group received 600 mg in a single oral dose; the second received 1200 mg divided into two administrations of 600 mg, each one every 12 h; the third received 1200 mg in a single oral dose. Prostatic levels of miocamycin were recorded after the administration of 1200 mg, divided into two administrations of 600 mg every 12 h. The pharmacokinetic analysis was carried out by applying a single-compartment kinetic model with zero-order absorption. The apparent duration of absorption (T) was about 0.55 h for all subjects. The area under the curve was 7.5767 +/- 0.2511 mg/h/l in the first group; 6.7333 +/- 0.6058 mg/h/l in the second group; and 18.6825 +/- 15.1555 mg/h/l in the third. The prostatic levels were five times higher than those in the serum at the same time.

Significant increase of IQ-type heterocyclic amines, dietary carcinogens in the plasma of patients with uremia just before induction of hemodialysis treatment.

The concentrations of 2-amino-3-methylimidazo(4,5-f) quinoline (IQ) and 2-amino-3,8-dimethylimidazo(4,5-f)quinoxaline (MeIQx), a family of mutagenic and carcinogenic heterocyclic amines, in the plasma of normal subjects (10 cases), patients with uremia receiving maintenance hemodialysis treatment (9 cases) and patients with uremia just before induction of hemodialysis treatment (5 cases) were determined by a high-performance liquid chromatography method. The plasma levels of IQ and MeIQx in uremic patients just before induction of hemodialysis treatment were 12.6 +/- 4.1 nM (mean +/- S.D., n = 5) and 10.0 +/- 2.3 nM (n = 5), respectively. In patients with uremia receiving maintenance hemodialysis treatment, IQ and MeIQx were detected in 4 and 2 out of 9 cases, respectively and the levels of those in the plasma were 4.1 nM (n = 4) and 1.7 nM (n = 2), respectively. However, IQ and MeIQx could not be detected in all normal subjects. These results indicate that uremic patients just before induction of hemodialysis treatment are actually exposed to higher levels of the carcinogenic heterocyclic amines, as compared with normal subjects and uremic patients receiving maintenance hemodialysis treatment.

Excretion of mutagens in sweat and faeces of man, and in serum, gastric juice and urine of rats, after oral dosing of niridazole or metronidazole.

Frameshift mutagens were isolated and concentrated from sweat and faeces of three healthy volunteers (non-smokers) of whom two received 750 mg metronidazole/person and one received 500 mg niridazole. The sweat samples were collected in a sauna a day before and 8 h after oral uptake of the medicaments. The faecal samples were those expelled 12 h before and after drug uptake. All extracts were tested for mutagenicity in the bacterial microtiter fluctuation test employing Salmonella typhimurium TA1538. No mutagenic activity was found with the samples obtained before the drugs were taken, whereas the samples collected after drug treatments were all mutagenic (P less than 0.05). In an animal experiment, female Wistar rats were used to study the time-course of the excretion of mutagens in serum, urine and gastric juice after uptake of 10-20 mg niridazole by gavage. Significant mutagenic activities (P less than 0.001) were found in serum 10 min after and in gastric juice 12h after treatment with niridazole. Non-significant but detectable mutagenicities were found in urine 12 h after treatment, when S. typhimurium G46 was employed as a test organism. These latter mutagenicities were significant (P less than 0.05) 24 h after treatment, they reached a peak of activity (P less than 0.01) 48 h post-administration and disappeared 12 h thereafter.

Disposition in rats and mice of 7-methoxy-2-nitronaphtho[2,1-b]furan.

The disposition of 7-methoxy-2-nitronaphtho[2,1-b]furan (MNNF), labelled with 14C in the furan ring (label 1) and in the methoxy group (label 2) has been studied in rats and mice. After i.p. administration to rat (5 mg/kg), both labelled species were absorbed by the lymphatics; and after oral administration, through the intestinal lumen. Excretion of the furan ring (label 1) is mainly urinary (44% dose in 24 h); label 2 was mostly expired as 14CO2 (48% dose in 24 h), indicating considerable demethylation. No target organ was found for MNNF, except liver and kidney. For both labelled species given orally, radioactivity was bound to the intestinal wall. Preliminary metabolic studies, using t.l.c. and h.p.l.c., have shown the presence of an urinary metabolite, namely, the glucuronide of 7-hydroxy-2-nitronaphtho[2,1-b]furan (15-20% of the urinary radioactivity). The remaining radioactivity comprises basic compounds, that bind to a cationic resin, which might be formed by enzymic reduction of the nitro group.

Mutagenicity of procarbazine for V79 Chinese hamster fibroblasts in the presence of various metabolic activation systems.

Even though procarbazine is mutagenic in most in vivo systems, a number of in vitro assays failed to indicate a positive effect. Since inappropriate metabolic activation in vitro is one explanation for these findings, the effects of procarbazine on V79 Chinese hamster fibroblasts in the absence and in the presence of either an S9 liver homogenate or hepatocytes from male rats were evaluated. The influence of enzyme induction was studied by performing experiments using S9 and hepatocytes both from non-treated and from Aroclor 1254-treated rats. Serum from procarbazine-treated rats was also tested for mutagenicity. Cytotoxicity was not strongly influenced by the presence of either S9 or hepatocytes, irrespective of whether Aroclor-induced or non-induced preparations were used. Without a metabolic activation system, and in the presence of S9 from non-induced animals, a weak mutagenic effect, i.e. an increased frequency of thioguanine-resistant clones, was observed in the cytotoxic dose range of 6000 micrograms/ml. In the hepatocyte-mediated assay, 2-6 micrograms/ml procarbazine proved to be mutagenic. Using the hepatocyte-mediated assay, a decrease in mutagenicity in the cytotoxic dose range was observed, reaching, at 6000 micrograms/ml in the case of hepatocytes from non-induced animals, a value almost identical to that observed without a metabolic activation system. Thus testing chemicals in the cytotoxic dose range only might lead to false conclusions, particularly if hepatocytes were used for metabolic activation. The use of liver preparations from Aroclor-pretreated rats led to much stronger mutagenic responses than those caused by non-induced material.(ABSTRACT TRUNCATED AT 250 WORDS)