Areolae of the Placenta in the Antarctic Minke Whale (Balaenoptera bonaerensis)

In this study, we examined the existence and structure of areolae and the steroidogenesis of areolar trophoblast cells in the Antarctic minke whale placenta morphologically and immunohistochemically. Placentas were collected from the 15th, 16th and 18th Japanese Whale Research Program under Special Permit in the Antarctic (JARPA) and 1st JARPA II organized by the Institute of Cetacean Research in Tokyo, Japan. The opening and cavity of fetal areolae formed by taller columnar trophoblast cells (areolar trophoblast cells) with long microvilli and a bright cytoplasm, as compared with the trophoblast cells of the chorionic villi interdigitating with the endometrial crypts, were recognized in observations of serial sections. The opening of the areolar cavity was hidden by chorionic villi with areolar trophoblast cells. Furthermore, a closed pouch-like structure lined by tall columnar cells similar to areolar trophoblast cells within the stroma of chorionic villi was noticed and continued to the areolar cavity, with the opening seen on serial sections. In a surface investigation of the chorion and endometrium by SEM, maternal (endometrial) areolae irregularly surrounded by endometrial folds were obvious. Moreover, we distinguished areolar trophoblast cells with long microvilli attached with many blebs from trophoblast cells. In our immunohistochemical observations, a steroidogenic enzyme, cytochrome P450 side chain cleavage enzyme (P450scc), was detected with strong immunoreactivity in trophoblast cells. However, areolar trophoblast cells showed weak or no immunoreactivity for P450scc.     

Nonequilibrium mechanics of active cytoskeletal networks

Cells both actively generate and sensitively react to forces through their mechanical framework, the cytoskeleton, which is a nonequilibrium composite material including polymers and motor proteins. We measured the dynamics and mechanical properties of a simple three-component model system consisting of myosin II, actin filaments, and cross-linkers. In this system, stresses arising from motor activity controlled the cytoskeletal network mechanics, increasing stiffness by a factor of nearly 100 and qualitatively changing the viscoelastic response of the network in an adenosine triphosphate-dependent manner. We present a quantitative theoretical model connecting the large-scale properties of this active gel to molecular force generation.     

Toxicity of wild juvenile “komonfugu” Takifugu flavipterus in the Bay of Sanriku Coast,Tohoku Area,Northern Japan

To clarify the mechanism of tetrodotoxin (TTX) accumulation in pufferfish, we compared the toxicity of two sets of wild juvenile “komonfugu” Takifugu flavipterus. The first set was sampled from Onisawa Fishing Port (FP) located in Okirai Bay, the Pacific Coast of Sanriku, Tohoku Area, Northern Japan. The second set was collected from the Onisawa FP and reared in an outdoor laboratory tank supplied with different seawater (Yoshihama Bay). The fish were sampled regularly and on the same days. The amount of TTX (mouse unit (MU)/fish) in the fish at Onisawa FP increased until 20 days and thereafter it did not change, while the amount of TTX in the fish in the laboratory tank remained low, and the TTX concentration (MU/g fish) decreased. Next, we compared the toxicity of wild juvenile T. flavipterus collected from Okirai Bay (Onisawa FP and Okirai FP) and Yoshihama Bay (Yoshihama FP). Large differences in TTX levels were observed among the fish from the three FPs. The amounts and concentrations of TTX in the fish at Onisawa FP were higher than those in the fish from the other two FPs. These results indicate that a large variation in toxic activity exists in the juvenile T. flavipterus in the bay of the Sanriku Coast.

     

An H5N1 highly pathogenic avian influenza virus that invaded Japan through waterfowl migration

In 2010, an H5N1 highly pathogenic avian influenza virus (HPAIV) was isolated from feces of apparently healthy ducks migrating southward in Hokkaido, the northernmost prefecture of Japan. The H5N1 HPAIVs were subsequently detected in domestic and wild birds at multiple sites corresponding to the flyway of the waterfowl having stopovers in the Japanese archipelago. The Hokkaido isolate was genetically nearly identical to H5N1 HPAIVs isolated from swans in the spring of 2009 and 2010 in Mongolia, but less pathogenic in experimentally infected ducks than the 2009 Mongolian isolate. These findings suggest that H5N1 HPAIVs with relatively mild pathogenicity might be selected and harbored in the waterfowl population during the 2009-2010 migration seasons. Our data provide "early warning" signals for preparedness against the unprecedented situation in which the waterfowl reservoirs serve as perpetual sources and disseminators of HPAIVs.     

Uterine Carcinosarcoma in a 2-year-old Female Wistar Hannover GALAS Rat

Carcinosarcomas are rare tumors in humans as well as rats and most commonly occur in the uterus. Recently, we observed a case of incidental carcinosarcoma of the uterus in a female Wistar Hannover GALAS [BrlHan:WIST@ Jcl (GALAS)] rat at 2 years of age. Histopathologically, the tumor was characterized by an admixture of malignant epithelial and nonepithelial elements. The carcinomatous components represented a type of endometrial carcinoma, consisting of glandular and solid proliferation of large-sized tumor cells. Prominent mitoses and tumor cell invasion were observed. The sarcomatous components were characterized by multifocal proliferation of severe atypical cells with cartilage matrix and were diagnosed as chondrosarcoma. Transitions between carcinomatous and sarcomatous components were observed, and many tumor cells in the solid lesion showed immunohistochemical reactivity with both cytokeratin and vimentin. Based on these findings, this tumor was diagnosed as a uterine carcinosarcoma. This is the first report of uterine carcinosarcoma in Wistar Hannover GALAS [BrlHan:WIST@Jcl (GALAS)] rats.     

Disinfectant resistance of Salmonella in in vitro contaminated poultry house models and investigation of efficient disinfection methods using these models

Salmonellaenterica subsp. enterica (Salmonella) shows disinfectant resistance by forming biofilms on solid surfaces. However, efficient disinfection methods to eliminate Salmonella biofilms from farms have not yet been examined in detail. In this study, more than 80% of Salmonella strains from farms in Yamagata prefecture, Japan, were biofilm producers. Regardless of the extent of their biofilm formation ability, their biofilms were highly resistant to hypochlorous acid on plastic surfaces. To establish efficient disinfection methods in farms, we developed in vitro Salmonella-contaminated poultry house models by depositing dust on ceramic and stainless-steel carriers in poultry houses for one month and culturing a representative Salmonella strain on the carriers. Biofilm-like structures, including Salmonella-like cells, were observed on the models by scanning electron microscopy. Salmonella was not efficiently removed from the models even by cleaning with a surfactant at 25/65°C and disinfection with quaternary ammonium compound or hypochlorous acid at 25°C; on the contrary, viable Salmonella cells increased in some tests under these conditions, suggesting that these models successfully simulate the highly persistent characteristics of Salmonella in farms. However, the persistent bacterial cells were markedly decreased by soaking in 65°C surfactant followed by rinsing with 80°C water, additional cleaning using chlorine dioxide or disinfection with dolomitic lime, suggesting the effectiveness of these methods against Salmonella in farms. Since many different disinfection conditions may be easily tested in laboratories, our models will be useful tools for establishing effective and practical disinfection methods in farms.     

Performance of a new carbon dioxide absorbent,Yabashi lime? as compared to conventional carbon dioxide absorbent during sevoflurane anesthesia in dogs

In the present study, we compare a new carbon dioxide (CO₂) absorbent, Yabashi lime^® with a conventional CO₂ absorbent, Sodasorb^® as a control CO₂ absorbent for Compound A (CA) and Carbon monoxide (CO) productions. Four dogs were anesthetized with sevoflurane. Each dog was anesthetized with four preparations, Yabashi lime^® with high or low-flow rate of oxygen and control CO₂ absorbent with high or low-flow rate. CA and CO concentrations in the anesthetic circuit, canister temperature and carbooxyhemoglobin (COHb) concentration in the blood were measured. Yabashi lime^® did not produce CA. Control CO₂ absorbent generated CA, and its concentration was significantly higher in low-flow rate than a high-flow rate. CO was generated only in low-flow rate groups, but there was no significance between Yabashi lime^® groups and control CO₂ absorbent groups. However, the CO concentration in the circuit could not be detected (≤5ppm), and no change was found in COHb level. Canister temperature was significantly higher in low-flow rate groups than high-flow rate groups. Furthermore, in low-flow rate groups, the lower layer of canister temperature in control CO₂ absorbent group was significantly higher than Yabashi lime^® group. CA and CO productions are thought to be related to the composition of CO₂ absorbent, flow rate and canister temperature. Though CO concentration is equal, it might be safer to use Yabashi lime^® with sevoflurane anesthesia in dogs than conventional CO₂ absorbent at the point of CA production.