Differential mutagenicity of N-methyl-N-nitrosocarbamate insectides in Escherichia coli strains having different DNA repair capacities

Four isogenic strains of Escherichia coli with the same auxotrophic marker (arg Fam--namely wild-type, uvrA-, polA- and recA-) were used for testing the lethalities and mutagenicities of 1-naphthyl N-methyl-N-nitrosocarbamate (nitroso-NAC), 3-methylphenyl N-methyl-N-nitrosocarbamate (nitroso-MTMC), and 3,4-dimethylphenyl N-methyl-N-nitrosocarbamate (nitroso-MPMC). The strains recA- and polA- showed a similarly higher sensitivity to killing than wild-type and uvrA- after treatments with each of the three chemicals, whereas the strains wild-type, uvrA-, and polA- were equally mutable by these compounds at equal doses. The strain recA- was hardly mutable by nitroso-NAC, but significant levels of Arg+ mutations were observed after treatments with nitroso-MTMC and nitroso-MPMC. These and previous results suggest that both nitroso-MTMC and nitroso-MPMC are similar in their mutagenicity pattern to N-methyl-N'-nitro-N-nitrosoguanidine whereas nitroso-NAC is similar to methyl methanesulfonate or X-rays, and that the major damage to DNA of the three agents is not excisable by the uvrA+-dependent excision repair, probably methylation in DNA.

Comparative studies of chromosomal aberration and mutagenicity of the trivalent and hexavalent chromium

The comparative cytogenetic and mutagenic effects between trivalent and hexavalent chromium were investigated. Five chromium compounds, K2Cr2O7 and K2CrO4 containing Cr6+, and Cr(CH3COO)3, Cr(NO3)3 and CrCl3 containing Cr3+, were examined for their ability to induce chromosomal damage in cultures of human leukocytes, for their reactivity with DNA by a rec-assay system and for mutagenicity in the E. coli Hs30R test system. Chromosome-breaking activity was significantly higher for the compounds with hexavalent than trivalent chromium, the efficiency being in the decreasing order K2Cr2OM greater than K2CrO4 greater than Cr(CHCOO)3 greater than Cr(NO3)3, CrCl3. In the rec-assay and mutation assay, hexavalent (K2Cr2O7 and K2CrO4) and trivalent Cr(CH3COO)3) compounds gave positive results, their mutagenic potential being higher in the same order of clastogenic magnitude.

[Simple method for producing 13NN and 15OO by proton bombardment of aqueous phase (author's transl)]

A simple method has been developed for the production of 13NN and 15OO by proton irradiation of aqueous solutions. 90 mCi of 13NN was obtained in a 200 ml. of He by using 1.0M NH4CI solution at pH 11 as the target with 10 min irradiation of 15 MeV, 10 microamperemeter protons. 80 mCi/min of 15OO was continuously obtained in a 200 ml of O2 by using pure water as the target with 40 MeV, 2 microamperemeter protons. The radiochemical purity of these short-lived radioactive gases obtained by this method was greater than 99.9% by passing through a single absorber.

[Caffeine-11C, ephedrine-11C and methylephedrine-11C: Synthesis and distribution in mice (author's transl)]

Caffeine, ephedrine and methylephedrine were labeled with carbon-11 by the action of methyliodide-11C on theophylline, norephedrine and ephedrine, respectively. Caffeine-11C was prepared in 44 min with a radiochemical yield of 40%, ephedrine-11C in 45 min with a 11% radiochemical yield and methylephedrine-11C in 36 min with a 43% radiochemical yield. When injected in mice intravenously, these products show a high uptake in the liver, the kidney and the blood for caffeine-11C and in the liver and the kidney for ephedrine-11C and methylephedrine-11C. The brain uptake for these products was found to be 2.4 to 3.9% of the injected dose per gram at 5 min after injection. These studies in mice have demonstrated that these products are potentially useful agents for the dynamic studies of the brain.

[Remote system for the mass production of short-lived radioisotopes in a cyclotron. Development of the system and radioisotope production]

A system was developed for producing short-lived radioactive substances (11CO, 11CO2, 13NN, 13NH3, 18F-, 62Zn2+, 123I-, etc.) on a scale enough for clinical use, which could also be used for analyzing them rapidly and for investigating their production methods, with less received dose by workers. The system enabled us to produce remotely several tens mCi of of short-lived radioactive susbtances readily usable for clinical diagnosis, continuosly for radioactive gases, 11CO, 11CO2 and 13NN, or repeatedly at short intervals for radioactive aqueous solutions of 13NH3, 18F-, etc. Employing this system, the average received dose per month was reduced considerably.

A simple and sensitive fluorometric assay method for taurine using high-voltage paper electrophoresis

A simple and sensitive fluorometric assay method for taurine (2-aminoethanesulfonic acid) has been developed. For the separation of taurine, high voltage paper electrophoresis subsequent to column chromatographic procedures was employed. Fluorescent product of taurine was yielded by spraying fluorescamine (4-phenylspiro [furan-2(3H), 1'-phthalan]-3, 3'-dione) and borate buffer on the paper, and the fluorescence was assayed spectro-fluorometrically after eluting with 50% ethanol. The linear relationship between the concentration of taurine and fluorescence developed was achieved over the concentration ranges of 0.5-10 nmoles, and the recoveries obtained were 90-100%. The specificity of this method for taurine was satisfactory and structural analogues involved in the metabolic pathway of taurine did not interfere with the assay. Examples for tissue levels of taurine in various organs of the rat as determined by this new method are also presented.

Studies on selenium-related compounds. V. Cytogenetic effect and reactivity with DNA

Five selenium compounds, Na2Se04, H2Se04, Na2Se03, H2Se03 and Se02, were tested for their capacity to induce chromosome aberrations in cultured human leukocytes and for their reactivity with DNA by a rec-assay system and inactivation of transforming activity in Bacillus subtilis. Chromosome-breaking activity was significantly higher for the compounds with four-valent than with six-valent selenium, the efficiency being in the decreasing order H2S03 greater than Na2Se03 greater than Se02 greater than H2Se04 greater than Na2Se04. Rec assay using B. subtilis with different recombination capacities suggested that damage to DNA was produced by selenites but not by selenates. The reactivity of selenites with DNA was also indicated by a significant loss of transformation of the tryptophan marker of B. subtilis DNA treated with H2Se03 and Se02.

Effects of short chain alcohols and hydrocarbon compounds on the adenylate cyclase of the skin

The cyclic AMP content of epidermal slices is increased by incubation with ethanol, the effect of which is dose-dependent from I to 5% concentration in the incubation media. n-Propanol and acetone are also effective at a concentration equimolar to 5% ethanol. Experimental results suggest that this effect of ethanol is due to activation of adenylate cyclase, rather than to the inactivation of cyclic AMP-phosphodiesterase.

Metabolism of maltose during surgery in patients with diabetes mellitus under general anesthesia

During a surgical operation under general anesthesia, maltose was administered at a rate of 1g/kg BW to 9 diabetic and 18 non-diabetic patients. The disappearance curve of maltose from blood was similar between diabetics and non-diabetics. Blood sugar tended to rise but no significant difference was found between the two groups. Lactic acid and pyruvic acid showed a tendency toward a rise, but the change was non-significant. NEFA and uric acid failed to change. Urinary excretion of maltose was not different between diabetics and non-diabetics. After 120 min., urinary excretion of maltose was similar between the two groups, but excretion as glucose was greater in the diabetic group.

Multiple forms of cyclic nucleotide phosphodiesterase in pig epidermis

Pig epidermal cyclic nucleotide phosphodiesterases (EC 3.1.4.16) have been partially purified by DEAE-cellulose column chromatography. At least three different forms of the epidermal phosphodiesterases were identified. They were cyclic GMP-specific, cyclic GMP- and cyclic AMP-hydrolyzing and apparently a cyclic AMP-specific enzyme: the first two forms were soluble and the last was the particulate enzyme. The cyclic GMP-specific soluble fraction had a relatively low Km, the cyclic GMP- and cyclic AMP-hydrolyzing fraction had a high Km for the respective substrates and the third particulate enzyme had both high and low Km values for cyclic AMP. The cyclic GMP-hydrolyzing enzyme was localized almost entirely in the soluble fraction, whereas cyclic AMP-hydrolyzing enzyme was distributed to both soluble and particulate fractions. Thus, our studies show that the multiple forms of pig epidermal enzyme differ distinctly in their substrate affinity, specificity and subcellular distribution.