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We isolated 607 independent nalidixic acid-resistant mutants from Bacillus subtilis. A 163 bp DNA segment from a 5' portion of the gyrA gene was amplified from the DNA of each mutant strain. After heat denaturation, the product was subjected to gel electrophoresis to detect conformational polymorphism of single-strand DNA (PCR-SSCP analysis). Mobility patterns of the two DNA strands from all the mutant strains examined differed from those of the parental wild-type strains. The patterns were classified into 13 types, and the DNA sequence of each type was determined. A unique sequence alteration was found in mutants belonging to each of the 13 types, defining 13 gyrA alleles. Eight were single base pair substitutions, four were substitutions of two consecutive base pairs and one was a substitution of three consecutive base pairs. Only three amino acid residues (Ser-84, Ala-85, and Glu-88) were altered in the deduced amino acid sequences of the mutated genes. We conclude that molecular typing based on the PCR-SSCP method is a powerful technique for the exhaustive identification of allelic variants among mutants selected for a phenotypic trait.

In healthy subjects, the blood volume (BV) increases rapidly after postural change from standing to the supine position. However, little is known about the effect of postural change on BV in long-term hemodialysis (HD) patients. Therefore, we have examined the BV change caused by adopting the supine position from standing by continuous hematocrit monitoring, using the CRIT-LINE instrument, in 8 anuric HD patients. The hematocrit was monitored for 25 min with the patient in the supine position just before HD. The percentage change in the BV (% Δ BV) was calculated from the hematocrit and approximated using the equation: % Δ BV = b – [1 – exp(–c × time (min)] –a × time (min). Coefficient a was the slope of the linear part in the % Δ BV, b was the magnitude of BV increase and c was the rate of BV increase. Then we examined the relationship between the coefficients (a, b and c) and clinical parameters. In all patients, % Δ BV increased quickly after adopting the supine position. The mean increases were 2.8 ± 0.6% after 5 min and 4.8 ± 0.5% after 25 min. There was a significant correlation between the value of % Δ BV calculated from the hematocrit and the value calculated using above equation (0.92 < r < 0.99, p < 0.001). Although coefficient a did not correlate with a clinical parameter, coefficient b showed a significant positive linear correlation with the serum albumin level (r = 0.816, p < 0.05) and coefficient c showed a significant positive linear correlation with the percentage change in interdialytic weight gain (r = 0.736, p < 0.05). Furthermore, based on the % Δ BV, we calculated the change in total BV, which had increased by 181.5 ± 21.9 ml after 25 min in the supine position. In conclusion, the change in the BV with time by continuous hematocrit monitoring using the CRIT-LINE instrument can be approximated by a modified monoexponential equation. BV increased quickly in HD patients after postural change from standing to the supine position.

A prolonged irradiation facility to study late effects on mice by continuous ƒÁ-ray irradiation at low-dose rates was established at the Institute for Environmental Sciences (IES), Aomori prefecture, Japan. Before starting studies of late effects, the absorbed doses to mice were estimated in detail. Three 137Cs ƒÁ-sources were individually used to expose mice in three irradiation rooms. The cages for mice were arranged so that the mean absorbed doses in the abdomen of a mouse would reach 8000, 400, 20mGy by exposures for about 400 days in respective rooms. The positions of the cages on the shelves of racks were presumed by using two air-ionization chambers whose ionization volume were about 12 and 1200 ml, respectively. Furthermore, by inserting TLD phosphors into the abdomens of mice, the absorbed doses were directly obtained under the actual exposure conditions. The absorbed dose distributions in air at the source level above the floor never showed an inverse-square law behavior with the distance from the source, and also never showed geometric symmetry in every irradiation room. Except for errors concerning the positions of the racks and cages, the uncertainties in the exposure doses were estimated to be about •}12% for a 8000 mGy group, 17% for a 400 mGy group and 35% for a 20 mGy group.

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