The Kitasato archives of experimental medicine最新文献

Mycobacterium leprae is an obligate intracellular parasite and grows within mononuclear phagocytes. When murine macrophages derived from the peritoneal cavities of CBA mice were infected in vitro with M. leprae (Thai-53 strain), intracellular multiplication was observed three weeks after infection. On the other hand, there was no increase in the number of heat-killed M. leprae at the same times after infection. Morphological studies showed that the growth rate of the bacteria increased by about 20-30% in medium supplemented with cycloheximide. With the addition of cycloheximide to the culture medium, metabolic activity of macrophages was decreased but infected cells were maintained in good condition and seldom floated off from the culture flask.

Mycobacterium leprae is an obligate intracellular parasite which grows within mononuclear phagocytes. In clinical cases, M. leprae reaches enormous numbers in the macrophage-rich granulomas of leprosy. Peritoneal macrophages from CBA mice were cultured in Waymouth medium containing fresh horse serum in Costar 3424 trays (24 wells, 16 mm in diameter) each containing 9 x 12 mm cover slips. This medium was supplemented with 0.5 micrograms/ml of cycloheximide. These cells were infected with M. leprae Thai-53 strain obtained by nude mice inoculation. Significant multiplication of the acid-fast bacilli in the macrophages was observed three weeks after inoculation. This experiment showed M. leprae mainly multiplied in cells and not by rephagocytization of M. leprae derived from destroyed cells.

In a previous paper, we have noticed the effectiveness of two further attenuated measles vaccines, i.e. AIK-HDC and Edmonston- Zagreb- HDC. In the present study the same strains are comparatively used for immunization of a limited number of children under 9 months of age. A seroconversion of 100% was observed. Following reimmunization, a significant increase of circulating antibodies for both strains was recorded. Two combined measles-mumps-rubella (MMR) vaccines were also produced by using the same measles strains. The seroconversion following utilisation of MMR prophylactics in susceptible children was 98.8 and 97.3 for AIK and Edmonston- Zagreb strains respectively.

Kitasatosporia strains were found to be resistant to an antibiotic, novobiocin. By a new method using novobiocin-containing agar medium, five Kitasatosporia strains, SK-3255, OM-5023, SK-3406, SK-3412 and SK-3421 were efficiently isolated from soils. These five strains were characterized in common by Rectiflexibiles, spores cylindrical with smooth surfaces, and no melanin formation. Two strains, SK-3255 and OM-5023 were taxonomically different from known species of the genus Kitasatosporia, while the two strains, SK-3406 and SK-3412 and the remaining strains SK-3421 were identified with K. phosalacinea and K. papulosa, respectively.

The ovary and eggs of adult tick Haemaphysalis longicornis (H. longicornis) infected with Babesia ovata (B. ovata), were examined at regular intervals of time. As a result kinetes could be detected in the ovary for the first time 6 days after engorgement. The kinetics could be classified into three types on the basis of their morphological characteristics. On the 2nd day after oviposition, round-formed protozoa were found in the ooplasm of the egg. In 5 days after oviposition, these round-formed bodies were transformed into club-forms. On the 9th day after oviposition, the kinetes were observed in the ooplasm. Morphologically, it seemed possible that B. ovata is transmitted by eggs of the tick, H. longicornis.

To elucidate the current status of foal diseases in Japan, clinico-pathological analysis was conducted on 237 foal autopsy cases. As a result, bacterial infection was identified as an important cause of foal death. Most of the bacteria isolated from these cases were ubiquitous, opportunistic, environmental organisms, known to be non-pathogenic to mature animals. Most of cases with bacterial infection were diagnosed as having hypogammaglobulinemia, i.e., failure of passive transfer. In addition, the mean weight of thymuses in foals affected by bacterial infection tended to be lower than that of foals without infection. These findings suggest that the common cause of foal diseases were mainly due to the opportunistic bacterial infections associated with the weakened immune function, serving as precursor to or promotor of infection.