Katsuaki Sugiura

Oxidative damage to neurons caused by the induction of microglial NADPH oxidase in encephalomyocarditis virus infection.

Reactive oxygen species (ROS) play an important role in diverse vital functions including host defense via anti-viral and anti-bacterial effects, but ROS also lead to peroxynitrite and hydroxyl radical production, which are powerful mediators of brain injury in brain inflammation. It is known that NADPH oxidases (NOX) are the major source of ROS. In the present study, NOX2 expression and distribution were examined after intracranial encephalomyocarditis virus B variant (EMCV-B) infection, which causes encephalitis. The reverse transcriptase (RT)-polymerase chain reaction (PCR) and immunohistochemistry showed that the expression and distribution of NOX2 were significantly up-regulated after EMCV-B infection in microglial cells, which invaded into the surrounding regions where neurons were subjected to oxidative stress. These findings suggest that the oxidative stress generated by NOX2 in activated microglial cells damages neurons and that this is an important process in the pathogenesis of EMCV-B infection.

Localization of insulinoma associated protein 2, IA-2 in mouse neuroendocrine tissues using two novel monoclonal antibodies.

AIMS Insulinoma-associated protein 2 (IA-2) is a member of the protein tyrosine phosphatase family that is localized on the insulin granule membrane. IA-2 is also well known as one of the major autoantigens in Type 1 diabetes mellitus. IA-2 gene deficient mice were recently established and showed abnormalities in insulin secretion. Thus, detailed localization of IA-2 was studied using wild-type and IA-2 gene deficient mice. MAIN METHODS To localize IA-2 expression in mouse neuroendocrine tissues, monoclonal antibodies were generated against IA-2 and western blot and immunohistochemical analyses were carried out in IA-2(+/+) mice. IA-2(-/-) mice served as a negative control. KEY FINDINGS Western blot analysis revealed that the 65 kDa form of IA-2 was observed in the cerebrum, cerebellum, medulla oblongata, pancreas, adrenal gland, pituitary gland, muscular layers of the stomach, small intestine, and colon. By immunohistochemical analysis, IA-2 was produced in endocrine cells in pancreatic islets, adrenal medullary cells, thyroid C-cells, Kulchitsky cells, and anterior, intermediate, and posterior pituitary cells. In addition, IA-2 was found in somatostatin-producing D-cells and other small populations of cells were scattered in the gastric corpus. IA-2 expression in neurites was confirmed by the immunostaining of IA-2 using primary cultured neurons from the small intestine and nerve growth factor (NGF)-differentiated PC12 cells. SIGNIFICANCE The IA-2 distribution in peripheral neurons appeared more intensely in neurites rather than in the cell bodies.

Cellular prion protein prevents brain damage after encephalomyocarditis virus infection in mice

Cellular prion protein (PrPC), a cell-surface glycoprotein normally associated with neurons, is also expressed in other cell types such as glia and lymphocytes. To further elucidate these roles of PrPC, wild-type prion protein gene (Prnp+/+) mice and Prnp-deficient (Prnp−/−) mice were infected with encephalomyocarditis virus B variant (EMCV-B) via an intracranial route. EMCV-B causes encephalitis and apoptotic cell death in vivo. Histopathological studies revealed that Prnp+/+ mice infected with 600 pfu of EMCV-B showed more severe infiltration of inflammatory cells, accompanied by higher activation of microglia cells around the hippocampus, than Prnp−/− mice; viz., no differences in the brain virus titer between these two lines of mice. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP, nick end-labeling (TUNEL) staining of the brain specimens revealed that the CA1 hippocampal pyramidal cells showed a larger number of apoptotic neurons in Prnp−/− than Prnp+/+ mice. Based on all these findings, PrPC may play certain roles in the induction of inflammation and inhibition of apoptosis in vivo.

A current life table and causes of death for insured dogs in Japan.

The life expectancies and causes of death were evaluated in 299,555 dogs insured in Japan between 1 April 2010 and 31 March 2011, of which 4169 dogs died during this period. The overall life expectancy of dogs was 13.7 years. The probability of death was high in the first year of life, lowest in the second and third years, and increased exponentially after 3 years of age. The life expectancy was 13.8 years in the <5 kg body weight group, 14.2 years in the 5-10 kg body weight group, 13.6 years in the 10-20 kg body weight group, 12.5 years in the 20-40 kg body weight group and 10.6 years in the ≥40 kg body weight group. As body weight increases, life expectancy tended to decrease except in the <5 kg body weight group. The probability of death increased as dogs got older for most potential causes of death. Neoplasia resulted in the highest probability of death, especially in the large and giant breed groups. Cardiovascular system disorders were the second major cause of death and the toy group had a probability of death significantly higher than the other breed groups at age 12+.

Breed, gender and age pattern of diagnosis for veterinary care in insured dogs in Japan during fiscal year 2010

We calculated the annual prevalence of diseases of 18 diagnostic categories in the insured dog population in Japan, using data from 299,555 dogs insured between April 2010 and March 2011. The prevalence was highest for dermatological disorders (22.6% for females and 23.3% for males), followed by otic diseases (16.4% for females and 17.2% for males) and digestive system disorders (15.7% for females and 16.4% for males). The prevalence of cardiovascular, urinary, neoplasia and endocrine disorders, increased with age; infectious diseases and injuries showed a high prevalence at young ages, and the prevalence of musculoskeletal and respiratory disorders showed a bimodal peak at young and old ages. A large variation in prevalence was observed between breeds for dermatological, otic, digestive, ophthalmological and cardiovascular disorders.

Use of veterinary antimicrobial agents from 2005 to 2010 in Japan

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Role of Cellular Prion Proteins in the Function of Macrophages and Dendritic Cells

The cellular isoform of prion proteins (PrPC) is expressed in hematopoietic stem cells, granulocytes, T and B lymphocyte natural killer cells, platelets, monocytes, dendritic cells, and follicular dendritic cells, which may act as carrier cells for the spread of its abnormal isoform (PrPSc) before manifesting transmissible spongiform encephalopathies (TSEs). In particular, macrophages and dendritic cells seem to be involved in the replication of PrPSc after ingestion. In addition, information on the role of PrPC during phagocytotic activity in these cells has been obtained. A recent study showed that resident macrophages from ZrchI PrP gene (Prnp)-deficient (Prnp-/-) mice show augmented phagocytotic activity compared to Prnp+/+ counterparts. In contrast, our study suggests that Rikn Prnp-/- peritoneal macrophages show pseudopodium extension arrest and up-regulation of phagocytotic activity compared to Prnp+/+ cells. Although reports regarding phagocytotic activity in resident and peritoneal macrophages are inconsistent between ZrchI and Rikn Prnp-/- mice, it seems plausible that PrPC in macrophages could contribute to maintain the immunological environment. This review will introduce the recent progress in understanding the functions of PrPC in macrophages and dendritic cells under physiological conditions and its involvement in the pathogenesis of prion diseases.

Establishment of a new glial cell line from hippocampus of prion protein gene-deficient mice.

Cellular prion protein (PrP(C)) is expressed not only in neuronal cells but also in non-neuronal cells such as astroglial cells. In the present study, the prion protein (PrP) gene (Prnp)-deficient astroglial cell line GpL1 from hippocampal cells of ZrchI Prnp(-/-) mice were established. Transfection of Prnp suppressed cell death in GpL1 cells under serum-free conditions. The PrP-expressing GpL1 cells showed increased superoxide dismutase activity compared to control GpL1 cells. These results suggest that the anti-oxidative activity of PrP(C) functions in not only neuronal cells but also astroglial cells possibly due to the increased anti-oxidative activity of astroglial cells.

Morbidity pattern by age, sex and breed in insured cats in Japan (2008–2013)

Objectives The aim of the study was to describe the morbidity pattern of different diagnostic categories in insured cats in Japan by age, sex and breed. Methods The annual incidence rates of having at least one insurance claim were calculated overall and stratified by diagnosis, age, sex and breed using data from insured cats in the period April 2008 to March 2013. Results The overall annual incidence rate of having at least one insurance claim was 4632 (95% confidence interval 4608–4656) cats per 10,000 cat-years at risk. The highest annual incidence rate was obtained for digestive system disorders, followed by urinary tract disorders and dermatological disorders. The incidence rates varied between breeds for most diagnostic categories: for cardiovascular system disorders, Scottish Fold, American Shorthair, Persian, Maine Coon, Norwegian Forest Cat, Ragdoll and Bengal had a higher annual incidence rate than crossbreeds. Conclusions and relevance This study provides comparative and quantitative estimates of morbidity pattern in insured Japanese cats. These estimates can be utilised by veterinary practitioners, breeders and owners in diagnostic decision-making, breeding and when selecting a new pet, respectively.

Quantitative risk assessment of the introduction of rabies into Japan through the illegal landing of dogs from Russian fishing boats in the ports of Hokkaido, Japan.

Japan has been free from rabies since 1958 and various preventive measures are in place protecting the country from the introduction of the disease. Historical reviews indicate that the illegal landing of dogs from Russian fishing boats in the ports of Hokkaido occurred frequently especially in the early 2000s and this could potentially be a source of introduction of rabies into Japan. The method of scenario tree modelling was used and the following entry and exposure pathway was considered the most likely route of rabies entry: a rabies-infected dog arriving on a Russian fishing boat lands in a port of Hokkaido in Japan, it becomes infectious, contacts and infects a susceptible domestic animal (companion dog, stray dog or wildlife). Input parameter values were based on surveys of Russian fishermen, expert opinion and scientific data from the literature. At present (2006-2015), the probability of the introduction of rabies as a result of one Russian fishing boat arriving at a port of Hokkaido is 8.33×10(-10) (90% Prediction Interval (PI): 7.15×10(-11)-5.34×10(-9)), while this probability would have been 7.70×10(-9) (90% PI: 6.40×10(-10)-4.81×10(-8)) in the past (1998-2005). Under the current situation (average annual number of boat arrivals is 1106), rabies would enter Japan every 1,084,849 (90% PI: 169,215-20,188,348) years, while the disease would have been introduced every 18,309 (90% PI: 2929-220,048) years in the past (average annual number of boat arrivals is 7092). The risk of rabies introduction has decreased 59 fold due to both the effective control of the issue of illegal landing of dogs and the decline in the number of Russian boat arrivals. Control efforts include education of Russian fishermen, establishment of warning signs, daily patrols and regular port surveillance of potential dog landing activity. Furthermore, scenario analysis revealed that the policy of mandatory domestic dog vaccination does not contribute effectively to Japans rabies prevention system under rabies-free situation. Although the current risk of rabies introduction is minimal, control measures against the illegal landing of dogs must be maintained. Further risk management measures, such as the removal of wildlife from the port area and regular monitoring of the rabies situation in Russia (particularly the easternmost regions), can be established to strengthen the current rabies prevention system in Hokkaido.