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One of the mechanisms of isoniazid resistance to Mycobacterium tuberculosis has been proved to be the chromosomal deletion of katG. Based on this finding, 22 isoniazid-resistant isolates of M. tuberculosis obtained in Japan and Yemen were analysed for katG by polymerase chain reaction and catalase activity. Only six (27%) of the 22 isolates were compatible with the mechanism (lack of amplification of katG and loss of catalase activity). In contrast, eight isolates (36%) were katG positive but catalase activity-negative and eight (36%) were positive for both factors, indicating that isoniazid resistance is multifactorial and the deletion of katG was not the major cause of resistance in the isolates examined in this study.

Accuracy amplified Mycobacterium Tuberculosis Direct Test (MTD), Amplicor Mycobacteria kit (Amplicor) and PCR method routinely used in the University of Tokyo Hospital (J. Clin. Microbiol. 31: 446-450 1991) were evaluated and compared with the same samples. The detection limits of MTD, Amplicor and PCR method (University of Tokyo) were 0.01-0.1 CFU/tube, 0.625 CFU/tube and 0.2 CFU/tube respectively, which were almost the same. These were shown to be at least as sensitive as the conventional culture techniques. The Tokyo Univ. method using radioisotope, takes up to 3 days, on the other hand 2 kits take 4-5 hours. These kits become useful tools for the early and rapid detection of M. tuberculosis in uncultured clinical specimens. But the risk of laboratory contamination and false-positive results remain. These must be further improved.

We report a 57-year-old man with Fisher's syndrome in whom both peripheral and central nervous system (CNS) lesions were detected. Clinical electrophysiological examinations including peripheral conduction studies, SEPs and BAEPs indicated conduction delay in the CNS as well as in the peripheral nerve.

The effect of LC-80 on infarct size induced by 6 hr coronary occlusion was studied in anesthetized dogs. LC-80 at a dose of 100 mg/kg, i.v. was injected 5 min after coronary occlusion and then infused at a rate of 50 mg/kg, i.v./hr until the heart was excised. The two risk areas were determined both by injecting a fluorescent dye (Thioflavin S) into the left atrium (in vivo) and by perfusing the non-occluded coronary bed with Monastral Blue (in vitro). The infarct size was determined by topographically tracing the area of myocardium unstained by triphenyltetrazolium chloride. Four zones such as Zone 1 (normal tissue), Zone 2 (tissue characterized by collateral blood flow), Zone 3a (tissue developing necrosis), Zone 3b (necrotic tissue) were delimited . As a result, (1) LC-80 significantly diminished the incidence of ventricular arrhythmias. (2) LC-80 significantly inhibited the decrease in myocardial free carnitine level in Zone 2 and Zone 3b. (3) LC-80 significantly reduced the infarct size expressed as a percentage of the risk area and increased the size of Zone 2. (4) In the electron microscopic findings, LC-80 showed lesser morphological changes such as swollen mitochondria and intracellular and extracellular edema, especially in Zone 2. (5) LC-80 may be useful for inhibiting the evolution of myocardial ischemic cell death both by the protection of ischemic myocardium and presumably by the increase in the collateral blood flow.

A novel protein-free synthetic medium has been developed for the culture of human squamous cell carcinoma cells. This medium, designated PF86-1, supports the serial subcultivation of six out of nine human squamous cell carcinoma cell lines in a protein-free, chemically defined condition without the adapting culture from serum-containing conditions. These cell lines growing in PF86-1 exhibited nearly equal potency to grow in massive culture without noticeable changes in morphology but presented a significantly decreased level of colony forming efficiency when compared with the cells cultured in serum-containing media, suggesting the implication of some autocrine mechanism. Interestingly, this medium supported the growth of normal human squamous cells of oral mucosa and skin for more than 2 mo. in the primary explant culture in spite of high levels of calcium ion concentration, where the overgrowth of fibroblasts as contaminant was not observed. These results suggest that PF86-1 supports the growth of cells derived from epidermal tissues selectively and provides the same defined condition for growth of malignant and nonmalignant human squamous cells. It seems, therefore, that PF86-1 allows investigations on the products of squamous cell carcinoma cells or on the differences of growth mechanisms between normal and neoplastic human squamous cells.