A solvent effect on the mutagenicity of tryptophan-pyrolysate mutagens in the Salmonella/mammalian microsome assay

The effect of adding organic solvents to the pre-incubation mixture in the Salmonella/mammalian microsome assay was examined in tests of the tryptophan-pyrolysate mutagens, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). Acetonitrile enhanced the mutagenic activity of Trp-P-1 and Trp-P-2 by an order of magnitude under optimal conditions. Strong enhancement of mutagenicity was also observed for the addition of ethanol, methanol, tetrahydrofurfuryl alcohol, tetrahydrofuran, 1,2-dimethoxyethane and N,N-dimethylformamide. The enhancing effect of acetonitrile on the mutagenicity of Trp-P-2 was found to be result of enrichment of the active metabolite in the assay system.

An aetiological study on spondylolysis from a biomechanical aspect

The authors report clinical studies on lumbar disorders (clinical symptoms, X-ray findings) in athletes in various sports. The sport items were divided into three groups according to the main dynamic load applied to the lumbar region. As a result, over 60% of the athletes suffered from "lumbago", and among them spondylolysis reached the high rate of 27%. Arising from these clinical observations, we performed biomechanical laboratory analyses on human cadaver material, axial compression and rotational bending. Our results suggest that the incidence of spondylolysis depends upon the extent and direction of the loads.

Absence of Carp's agent in sera of patients with multiple sclerosis in Japan

A study was devised to test for Carp's agent in the sera of Japanese patients with multiple sclerosis (MS). The sera were obtained from 17 patients with definite MS and six patients with possible MS. Strain C3H mice were given an intraperitoneal injection of 0.1 mL of each serum. One week before and 1, 3, and 6 weeks after inoculation, blood drops from tail tip were smeared and polymorphonuclear leukocytes (PMNLs) were counted. Although the experimental animals were kept under careful control, substantial fluctuation in the number of PMNLs occurred, and the variations of PMNL count in the experimental groups were all within the normal range. We conclude that there is no Carp's agent in the sera of patients with MS in Japan.

A sensitive assay for mutagenic activity of N-nitrosamines and its use for detection of modulators of the mutagenicity

By carrying out the pre-incubation of bacteria with N-nitrosamines under acidic conditions, the mutagenicity of N-nitrosodimethylamine on Salmonella TA100 and E. coli WP2 try, hcr was detected with increased sensitivity, compared to usual assays in neutral buffers. Using this modified assay system, compounds have been screened for their modulating effects on N-nitrosamine-mediated mutagenesis and the following were found to be inhibitors: cysteine, cysteamine, bisulfite, n-propylamine, n-butylamine, n-hexylamine, n-octylamine, n-nonylamine, serotonine, tryptamine, epinephrine, norepinephrine and oleic acid. The mechanisms of inhibition are discussed.

Histopathological study on effects of potassium aspartate on the hypothalamus of rats

Rats of various ages were treated orally or intraperitoneally with potassium aspartate. The dose required to induce hypothalamic lesion varied considerably by the age of animals and route of administration. Additional experiment, in which the animals were orally treated three times a day with potassium aspartate in dose levels between the maximum safety dose and minimum lesion-producing dose in the preceding single dose study, revealed no hypothalamic lesion at all in any animals of each age group. In this condition, the maximum safety dose was 3--5 times as large as that in single dosage administration experiment. Regarding the safety evaluation of potassium aspartate preparations, brief discussions on some points in extrapolation of the results of the present experimental study to the clinical use were made.

Rare occurrence of the tetratype tetrads in Saccharomycodes ludwigii

Genetic data suggesting the absence of crossover in Saccharomycodes ludwigii have been described. Tetrad data obtained from 888 asci from 60 pairs of genes with 22 genetic markers showed the absence of tetratype asci, except for 5 asci in which a single pair of alleles showed tetratype segregation to the other genetic markers in each ascus. Spore arrays in the linear asci showed that the + - + - and + - - + (or - + + -) asci occurred at almost equal frequencies. The two coherent spores at each end of an ascus were always marked with different alleles of a gene.