. Subjects were 620 female nurses (Average age: 23.9) who started their careers in April 1997 and continued working in the same hospitals for two years and three months until the time of the survey. A questionnaire consisting mainly of items concerning sleep disorders from the Japanese version of the Pittsburgh Sleep Quality Index was distributed to the subjects.Results: Significant associations were observed between working on night shift and the use of alcoholic beverages to help induce sleep, and between working on night shift and daytime drowsiness. Significant differences were also observed between two and three-shift systems with regard to subjective sleep quality. Moreover, average hours of sleep were significantly associated with three related sleep items: subjective sleep quality, difficulty in getting to sleep, and daytime drowsiness. Conclusion: Results suggest that in Japanese shift-work systems, sufficient sleep hours are needed for nurses who work night shift to ensure good quality of sleep and consequently better services for patients. (J Occup Health 2001; 43: 150-156)

Osteoporosis caused by exposure to microgravity represents a serious clinical concern, but the mechanisms have yet to be fully elucidated. The present research aimed to elucidate the effects of microgravity environments on bone turnover, with a specific focus on changes in bone resorption markers such as type I collagen cross-linked N-telopeptides (NTx) and deoxypyridinoline (Dpyr), for which scant data are available regarding detailed time course. Methods using 6 degrees head-down bed rest were utilized to simulate a microgravity environment. Eleven adult male volunteers underwent 6 degrees head-down bed rest for 14 days; measurements were made of serum and urine Ca concentrations, in addition to osteocalcin (OC), bone alkaline phosphatase (ALP), NTx, and Dpyr as bone turnover markers. By the end of bed rest, concentrations of bone ALP had significantly increased, but OC displayed a tendency toward decrease. Concentrations of Dpyr significantly increased from day 6, remaining elevated until the end of bed rest. Concentrations of NTx significantly increased on day 13 and at the end of bed rest. Serum and urinary concentrations of Ca increased significantly at the end of bed rest. Bone ALP represents a relatively early marker of osteoblast differentiation at the matrix maturation phase and OC is a late marker in osteoblast differentiation at the calcification phase. The present results therefore suggest an absolute increase in bone resorption and normal or reduced bone formation, together causing prominent uncoupling and rapid bone loss after simulated microgravity. Moreover, the present results suggest that bone resorption is enhanced at an early stage of exposure to microgravity environments.

The largest nationwide active surveillance of four Measles‐Mumps‐Rubella (MMR) vaccines was conducted in Japan. A total of 1255 pediatricians actively participated in the study, which comprised 8.6% of all members of the Japanese Pediatric Society. The total number of registered recipients of MMR vaccines was 38 203. They were arbitrarily given one of the MMR vaccines produced by three makers (Takeda, Osaka city, Kitasato Minato‐ku, Tokyo and Biken Suita city, Japan) or the standard MMR vaccine made of designated strains (Kitasato's measles‐AIK‐C, Biken's mumps‐Urabe Am9 and Takeda's rubella‐To336) produced by Takeda, Kitasato and Biken and were observed for 35 days. The rates of virologically confirmed aseptic meningitis per 10 000 recipients were 16.6, 11.6, 3.2 and 0 for the standard MMR, Takeda MMR, Kitasato MMR and Biken MMR vaccines, respectively. The incidence of convulsions between 15 and 35 days was the highest with the standard MMR vaccine and the incidence of fever associated with vomiting occurring between 15 and 35 days (symptoms relevant to aseptic meningitis) were also the highest with the standard MMR vaccine. The incidence of parotid swelling was the lowest with Takeda MMR vaccine. This surveillance revealed that incidences of aseptic meningitis after administration of the standard MMR vaccine and of Biken MMR vaccine were different. This posed questions about the manufacturing consistency of the Urabe Am9 mumps virus vaccines. On the other hand, the National Institute of Health found that the biological characteristics of the Urabe Am9 mumps virus contained in the standard MMR vaccine and in the Biken MMR vaccine were different. The Biken Company reported that the mumps vaccine in the standard MMR vaccine was a mixture of two Urabe Am9 mumps vaccine bulks; one identical to that contained in the Biken MMR vaccine and the other produced by a different manufacturing process.

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