Toshitaka Nakahara

Legionella pneumophila in Rainwater on Roads

During rain, transient puddles form on roads, and this water is splashed into the air by moving vehicles. To determine whether this water contains Legionella pneumophila, we collected samples from roads. We found that L. pneumophila are abundant in these puddles, especially during warm weather.

Risk factors for intrahepatic cholangiocarcinoma: a possible role of hepatitis B virus

Summary.  There are several established risk factors for intrahepatic cholangiocarcinoma (ICC), namely primary sclerosing cholangitis, fibropolycystic liver disease, parasitic infection, intrahepatic biliary stones and chemical carcinogen exposure. However, the majority of patients with ICC do not have any of these risk factors. Therefore, identification of other risk factors is warranted for the prevention and early detection of ICC. We evaluated the risk factors for ICC in a large‐scale cohort study in the province of Osaka, Japan. This retrospective cohort study included 154,814 apparently healthy individual blood donors, aged 40–64 years at the time of blood donation in the period 1991–1993. The average observation period was 7.6 years, resulting in 1.25 million person‐years of observation. Incident ICC cases were identified by linking the blood‐donor database to the records in the population‐based cancer registry for the province. There were 11 incident ICC cases during follow‐up, with an incidence rate of 0.88 per 100 000 person‐years. Compared with subjects aged 40–49 years, the subjects aged 50–54 years and 55–59 years had a significantly higher risk for ICC (hazard ratio [HR] = 5.90; 95%CI:1.08–32.31 and 11.07; 95%CI:1.98–61.79, respectively). Compared with those with ALT level of 19 Karmen Units (KU) or less, subjects with ALT level of 40 KU or higher had a significantly higher risk for ICC (HR: 8.30; 95%CI:1.47–46.83). Compared with those who tested negative for both HBsAg and anti‐HCV, those who tested HBsAg‐positive had a significantly higher risk for ICC (HR: 8.56; 95%CI: 1.33–55.20). Our results suggest that HBV infection and liver inflammation are independently associated with ICC development. These findings need to be verified by further large cohort studies.

Trends of stomach cancer mortality in Eastern Asia in 1950–2004: comparative study of Japan, Hong Kong and Singapore using age, period and cohort analysis

To characterize the temporal trends of stomach cancer mortality in Eastern Asia and to better interpret the causes of the trends, we performed age, period and cohort analysis (APC analysis) on the mortality rates in Japan, Hong Kong and Singapore during 1950–2004, as well as the rates in the US as a control population. For the APC analysis, Holfords approach was used to avoid the identification problem. Age‐standardized mortality rates (ASMR) decreased consistently in all four areas during the observation period in both males and females. Japan had the highest ASMR in both sexes, followed by Singapore, Hong Kong and the US, but the differences in ASMR among the four areas diminished with time. The results of APC analysis suggested that the decreasing mortality rates in Eastern Asia were caused by the combination of decreasing cohort effect since the end of the 1800s and decreasing period effect from the 1950s. The US showed similar results, but its decreases in the period and cohort effect preceded those of Eastern Asia. Possible causes for the decrease in the cohort effect include improvement in the socioeconomic conditions during childhood and a decrease in the prevalence of H. pylori infection, while possible causes for the decrease in the period effect include a decrease in dietary salt intake and improvements in cancer detection and treatment. These findings may help us to predict future changes in the mortality rates of stomach cancer.

The Relationship Between Thiamine Deficiency and Performance of a Learning Task in Rats

We have been investigating the relationship between learning and thiamine. Electrical stimulation of mesencephalic periaqueductal gray matter (PAG) is known to have an aversive effect and elicits spontaneous instrumental escape behavior. We taught rats to press a lever to escape from the pain of electrical stimulation by learning to turn a switch off. Then we examined the relationship between learning and the thiamine concentration in various portions of the brain.(1) One group of rats was given a normal diet and another group was given a thiamine-deficient diet which contained half of the amount of thiamine present in the normal diet. We measured the response time required for each rat to react by moving after an electrical impulse was applied, and the running time during which the rat was moving from the starting point to the end point to press a lever. The rats that were fed the thiamine-deficient diet showed a slower response time and a longer running time than the rats fed the normal diet.(2) We divided the rats fed the normal diet into two groups, one group trained to switch off a lever and the other group not trained for such a task. We found that the thiamine concentration in the blood of the rats in the trained group was significantly higher than that in the group without training.

A patient with Legionnaires' disease transferred after a traffic accident.

Legionnaires’ disease (LD) ranks among the three most common causes of severe pneumonia, but is often not specifically diagnosed. Among patients with LD, 40% to 50% of the patients develop neuromuscular signs and symptoms. A patient with LD transferred to our department after a traffic accident. When the patient arrived at our hospital, his respiratory rate was 27 breaths per min. His pulse was 148 beats per min and blood pressure was 116/57 mm Hg. Temperature was 39.6°C. He had copious watery diarrhoea and had been diagnosed as having acute gastroenteritis. The patient had urinary incontinence, gait disturbance, mild headache, fatigue and excessive decrease in spontaneous speech. A urinary antigen test for Legionella pneumophila turned out to be positive. LD commonly involves the neuromuscular system. Although this may be an atypical case of LD, it implies the need for awareness of LD.

Key Players in Health Promotion Policy in the Northern Part of the Western Pacific

Key players in the health promotion policy in the northern part of the Western Pacific Region are usually the governments and their related nongovernmental organizations (NGOs). As NGOs the International Union for Health Promotion and Education and its branch in the northern part of the West Pacific (IUHPE/NPWP) are supportive of governmental work on health promotion. Nowadays health promotion is gradually linking with health, medical, and welfare services to act against lifestyle-related diseases in the middle-aged and elderly population from the viewpoint of prevention, early detection, and health guidance.

Effect of 23-valent pneumococcal polysaccharide vaccine on medical expenses in Japan

Results Period A: From April 2009 till March 2012 Period B: From April 2012 till September 2012 The medical expenses for pneumonia of the vaccinated group (n=13689) and the non-vaccinated (n=126110) group are compared using the medical practitioners’ receipt for health insurance claim. The medical examination rates in Period A were 0.403 per year in the vaccinated and 0.227 per year in the non-vaccinated. Those in period B were 0.549 in the vaccinated and 0.331 in the non-vaccinated. The increasing rate of the vaccinated seems to be suppressed compared to non-vaccinated. Medical expenses in Period A were £365.2 in the vaccinated and £293.9 in the non-vaccinated. Those in Period B were £371.9 in the vaccinated and £172.1 in the non-vaccinated. The increase in medical expense seems to be suppressed by the vaccination. Conclusion The rate of the vaccinated in this prefecture is small. And the Period B is too short. Also it seems that those that are vaccinated have some diseases or are compromised. However the vaccination seems to be effective in reducing medical examination rate of pneumonia and reducing the medical expenses for it. These data have some limitations. Pneumonia on the medical practitioners’ receipt is not only caused by pneumococcus but also other causes such as virus. As the bills of medical treatment are issued every month, rates of diseases are sometimes overestimated. And the medical expenses for the inpatient was not calculated as they were not admitted only for pneumonia. Effect of 23-valent pneumococcal polysaccharide vaccine seems to reduce pneumonia and medical expenses even in a local area.