[Dynamic computed tomography (CT) in the rat kidney and application to acute renal failure models].

Renal dynamic CT scanning is suitable for determining the excretion of contrast medium in the cortex and medulla of the kidney, which is valuable for understanding the pathogenesis of disease processes in various conditions. This form of scanning would be convenient for use, if a method of application to the rat kidney were available. Therefore, we developed a method of applying renal dynamic CT to rats and evaluated the cortical and medullary curves, e.g., the corticomedullary junction time which is correlated to creatinine clearance, in various rat models of acute renal failure. The rat was placed in a 10 degrees oblique position and a bilateral hilar slice was obtained before and 5, 10, 15, 20, 25, 30, 40, 50, 60, 80, 100, 120, 140, 160 and 180 sec after administering 0.5 ml of contrast medium using Somatom DR. The width of the slice was 4 mm and the scan time was 3 sec. The corticomedullary junction time in normal rats was 23.0 +/- 10.5 sec, the peak value of the cortical curve was 286.3 +/- 76.7 Hounsfield Unit (HU) and the peak value of the medullary curve was 390.1 +/- 66.2 HU. Corticomedullary junction time after exposure of the kidney was prolonged compared to that of the unexposed kidney. In rats with acute renal failure, the excretion pattern of contrast medium was similar in both the glycerol- and HgCl2-induced acute renal failure models.(ABSTRACT TRUNCATED AT 250 WORDS)

[Rapid detection and identification of mycobacterial DNA by PCR].

We have developed a highly sensitive and rapid PCR assay for detection and identification of mycobacterial species. Two sets of PCR primers were prepared; one was for the 19 kDa antigen gene and the other for the dna J gene. The PCR for 19 kDa antigen gene was found to be specific to the M. tuberculosis complex; M. tuberculosis, M. bovis and M. africanum. On the other hand, the PCR for the dna J gene was able to detect a broad spectrum of mycobacterial species including M. tuberculosis, M. avium, M. intracellulare and M. kansasii. The sensitivity of PCR was similar to that of the culture method for precultured M. tuberculosis whereas PCR was much more sensitive than the culture for clinical samples. The procedure of decontamination by sodium hydroxide for clinical samples could reduce the viability of M. tuberculosis while it did not affect mycobacterial DNA. The nucleotide sequence homologies among major mycobacteria were also determined following PCR for the dna J gene. This allowed us to make restriction maps for each mycobacterium. We have demonstrated that the PCR-RFLP for the dna J gene will be a useful laboratory test for rapid identification of tuberculous and nontuberculous mycobacterial species.