Analysis of combined effects of benzene with radiation on chromosomes in cultured human leukocytes

Three experiments were carried out on 53-hr cultured human leukocytes on chromosome mutagenicity of benzene with particular reference to combined effects with gamma-radiation and inhibitory effect on rejoining of radiation-induced chromosome breaks. The results and their analyses were summarized as follows: 1) Benzene can induce mainly chromatid-type deletions, especially gaps, suggesting that the cells in their late S-G2 stage have a higher susceptibility to chromosome breakage by benzene. 2) The aberration tield of dicentrics and rings induced by 100 rads irradiation can significantly be enhanced by the treatment of benzene equal to or in excess of 0.2 mM. 3) Quantitative analyses using newly defined "Synergetic effect factor" revealed that combined cytogenetic effect of benzene with radiation could be synergetic exclusively in dicentrics and rings, being almost additive in the other types of aberration. 4) The experiment with dosage fractionation method showed that the more strongly benzene could inhibit the rejoining of radiation-induced chromosome breaks, the higher concentration it was treated at. Related iwth these results, possible inducps, and the repair and its inhibition of radiation-induced DNA-strand(s) breaks. Further studies for related effects by benzene are needed on protein synthesis, activities of repair enzymes and fine structure of chromosomes.

Tissue pressure measurements as a determinant for the need of fasciotomy

An experimental and clinical tehcnique of measuring tissue pressures within closed compartments demonstrates a normal tissue pressure is approximately zero mmHg, and increased markedly in compartmental syndromes. There is inadequate perfusion and relative ischemia when the tissue pressure within a closed compartment rises to within 10-30 mm Hg of the patient's diastolic blood pressure. Fasciotomy is usually indicated, therefore, when the tissue pressure rises to 40-45 mm Hg in a patient with a diastolic blood pressure of 70 mm Hg and any of the signs or symptoms of a compartmental syndrome. There is no effective tissue perfusion within a closed compartment when the tissue pressure equals or exceeds the patient's diastolic blood pressure. A fasciotomy is definitely indicated in this circumstance, although distal pulses may be present. The measurement of tissue pressure aids in the early diagnosis and appropriate treatment of compartmental syndromes.

Organic photoconductive layers sensitized with triarylcarbonium salts

The electrophotographic layer consisting of poly-3,6-dibromo-N-vinylcarbazole was sensitized with twenty-seven kinds of triarylcarbonium salts. The carbonium salt compounds used have the formula: [equation] The novel sensitizers differ in two points from the well-known triphenylmethane dyestuffs sensitizers for the organic electrophotoconductors. First, the triphenylmethane dyestuffs have at least two radicals such as amino or dimethylamino radical. The novel sensitizers have not such a radical. Second, the novel sensitizers have an extreme ability to increase the photosensitivity of organic photoconductors. When the photoconductive polymer sensitized with carbonium salts is applied to semitransparent paper, cellophane papers or plastic sheet, a transparent electrophotographic material can be obtained. These materials are superior to sensitized zinc oxide paper in photosensitivity. Such a transparent material can be used as a master for diazo copy, for overhead projection copy, or for slides.