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Takuya Yano

Publications and source records attributed to Takuya Yano.

5 recordsLinked to original sources
PubMed2003

[Poliovirus uptake into and excretion from oysters: a model experiment for elimination of Norwalk-like viruses from oysters].

Outbreaks of gastroenteritis caused by Norwalk-like viruses are often induced by the consumption of raw shellfish such as oysters. Incidences reach a peak during the cold season in Japan, when seawater temperatures fall below 10 degrees C. We investigated oysters' uptake and excretion of viruses, over varying lengths of exposure, monitoring the effects of changes in temperature and flow rate of seawater, and the presence of plankton. The study was performed using a poliovirus and an experimental circulatory system, which was framed on the same principle as a model practically used for the depuration of oysters. Polioviruses present in the seawater were taken rapidly into the midgut gland of oysters. However, virus levels detected in oysters at both 10 degrees C and 20 degrees C were decreased to approximately 1/1,000 to 1/10,000 within 6 hrs after the circulatory seawater was replaced by UV irradiated seawater. These results demonstrate the effectiveness of the circulatory depuration system for the elimination of poliovirus from oysters, and indicate that controlling the temperature and flow rate of the circulatory system could decrease the risk of NLV infection.

Animals↗
PubMed2003

[Efficacy of influenza vaccine for young children in Mie Prefecture in the 1999/2000 prevalent season].

PURPOSE: The purpose of this survey was to investigate the efficacy and safety of influenza HA vaccine for children between 1 and 6 years of age in Mie Prefecture during the 1999/2000 prevalent season. METHODS: We surveyed clinical data for children aged between 1 to 6 who visited five clinics in Mie Prefecture. Dividing them into vaccinated and non-vaccinated groups, we surveyed their basic properties, disease histories and manifestation of symptoms. The survey was performed with the consent of parents who were informed of the purpose. We also surveyed the adverse effects within 48 hours after vaccination. The serum HI titers of the vaccinated children were sampled three times: before the first vaccination and after the first and second vaccinations. The data were analysed with the chi-squared test and a multiple logistic model. RESULTS: The frequency of febrile episodes above 38 degrees C was significantly lower in the vaccinated than the non-vaccinated group. While the relative risk for the entire survey period was 0.79, it declined to 0.62 during the peak period of the epidemic. Furthermore, the odds ratio was 0.42 by the multiple logistic model. Among the vaccinated group, the pattern in the increase of HI titer after vaccination varied depending on the species of vaccine antigen. In addition, the frequency of febrile episodes above 38 degrees C was significantly lower in the group which had an HI titer to A/Sydney antigen of 1:40 or more than in these with values below 1:40. CONCLUSION: The relative risk of febrile episodes above 38 degrees C during the influenza prevalent season was 0.62 or below, and vaccine efficacy was 38 percent or above. Considering the significant difference in the frequency of febrile episodes between the groups with HI titers above and below 1:40, it is necessary to study strategies for those with a low response.

Child↗
PubMed2002

[Contamination of oyster sea farm with the Norwalk virus: mechanisms and control].

The Norwalk virus(NV) is widely known as a cause of nonbacterial food poisoning, infant diarrhea, and acute gastroenteritis in the winter months between November and March. While it is strongly suspected that NV that is excreted by humans flows into coastal seawaters via rivers and wastewater treatment facilities to contaminate oysters that are grown in farms in the area, light has yet to be shed on the behavior of this virus in the natural environment. We therefore conducted a polymerase chain reaction (PCR) survey of NV levels in the aquatic environment of the oyster bed area of the Shima region in Mie Prefecture, whereupon the NV was detected in marine sediment, oysters, and mule clams even during the summer months, when food poisoning is infrequent. In order to assess their similarity to human-derived strains, the detected viruses and their human-derived counterparts were subjected to genetic analysis, whereupon some of the detected viruses were found to be remarkably similar to those that were previously detected in humans infected with NV. In the interests of examining methods for decontaminating NV-contaminated oysters, we also conducted an assessment on a system of virus decontamination that focuses on seawater temperature and oyster metabolism, using Poliovirus Sabin strain. The decontamination system mentioned above was a closed loop, water circulating system, built on the same principles as those actually in use at oyster farms. Our experiment indicated that at seawater temperatures of both 10 degrees C and 20 degrees C, virus placed into the water tank was rapidly incorporated into the midgut glands of the oysters. Thereafter, when seawater irradiated with UV was circulated, the virus count in the oysters fell from 1/1,000 to 1/10,000 within 6 hours. These results indicated the utility of this system for virus decontamination, suggesting the possibility of significantly alleviating the risk of NV infection in humans by using this system to maintain the seawater temperature within the decontamination tank above a certain temperature, and to perform decontamination with an adequate water flow.

Animals↗