Nishii Kazuhiro

Background and aims Elderly individuals who suffer a fracture develop a gait disturbance and require prolonged bedrest. A fracture has a massive impact both physically and mentally and markedly diminishes quality of life. A new form of therapeutic exercise that mitigates the abrupt decrease in bone density in postmenopausal women must soon be developed so that those problems can be avoided. Methods The current study used a model of the decrease in bone density in ovariectomized mice to simulate postmenopausal women. The stimulus was provided by a shaking horizontal platform rotating in a circular motion. Results Comparison of the +/+ (ovariectomized/stimulated) group and +/- group indicated a significant decrease in BV/TV (p < 0.01), Tb.Th (p < 0.01), and Tb.N (p < 0.05) in the +/+ group and a significant increase in OV/BV (p < 0.01), OV/ OS (p < 0.01), BFR/BV (p < 0.01), dLS/BS (p < 0.05), MS/BS (p < 0.05), BRs.R (p < 0.01), and Tb.Sp (p < 0.01) in the +/+ group. Physical therapy to prevent a decrease in bone density was studied via stimulus in the form of rotation of a platform. Analysis of bone histomorphometry revealed lessening of the decrease in bone density of the lumbar vertebrae, a feat that the stimulus from conventional physical therapy had failed to achieve. Conclusion The current study delivered a shaking stimulus to mice in a model of postmenopause. Analysis of bone histomorphometry of the lumbar vertebrae suggested lessening of the abrupt decrease in bone density of trabecular bone. If this finding is used clinically, it could lead to physical therapy exercise that would be able to prevent compression fractures of the lumbar vertebrae.

After finding tonsil-like structures near the entrance of vagina of a laboratory shrew (Suncus murinus), which we subsequently designated as vaginal tonsils, we performed detailed immunohistochemical and developmental studies. The location of T and B cells in the vaginal tonsils differed from that in the palatine tonsils or that in the lymphoid nodes of other animals. The boundary between the germinal center region and the region encompassing follicular interfollicular tissue was not clear. B cells were widely distributed and very dense in the parenchyma, but they were scattered in the epithelial area (B cells were present in around 90% of the vaginal tonsil tissue). In contrast, T cells were scattered in the parenchyma and in the epithelial area (T cells were present in around 10% of the vaginal tonsil tissue). B cells were more prominent than T cells throughout the development of these structures and the epithelium was invaded by many immigrating cells. The size of the vaginal tonsils changed during postnatal development. Vaginal tonsils are structurally similar to other tonsils, and they may function to protect the vagina from infection.

Togawa H, Nakanishi K, Mukaiyama H, Hama T, Shima Y, Sako M, Miyajima M, Nozu K, Nishii K, Nagao S, Takahashi H, Iijima K, Yoshikawa N. Epithelial-to-mesenchymal transition in cyst lining epithelial cells in an orthologous PCK rat model of autosomal-recessive polycystic kidney disease. Am J Physiol Renal Physiol 300: F511-F520, 2011. First published November 17, 2010; doi:10.1152/ajprenal.00038.2010.-In polycystic kidney disease (PKD), cyst lining cells show polarity abnormalities. Recent studies have demonstrated loss of cell contact in cyst cells, suggesting induction of epithelial-to-mesenchymal transition (EMT). Recently, EMT has been implicated in the pathogenesis of PKD. To explore further evidence of EMT in PKD, we examined age-and segment-specific expression of adhesion molecules and mesenchymal markers in PCK rats, an orthologous model of human autosomal-recessive PKD. Kidneys from 5 male PCK and 5 control rats each at 0 days, 1, 3, 10, and 14 wk, and 4 mo of age were serially sectioned and stained with segment-specific markers and antibodies against E-cadherin, Snail1, beta-catenin, and N-cadherin. mRNAs for E-cadherin and Snail1 were quantified by real-time PCR. Vimentin, fibronectin, and alpha-smooth muscle actin (alpha-SMA) expressions were assessed as mesenchymal markers. E-cadherin expression pattern was correlated with the disease pathology in that tubule segments showing the highest expression in control had much severer cyst formation in PCK rats. In PCK rats, E-cadherin and beta-catenin in cystic tubules was attenuated and localized to lateral areas of cell-cell contact, whereas nuclear expression of Snail1 increased in parallel with cyst enlargement. Some epithelial cells in large cysts derived from these segments, especially in adjacent fibrotic areas, showed positive immunoreactivity for vimentin and fibronectin. In conclusion, these findings suggest that epithelial cells in cysts acquire mesenchymal features in response to cyst enlargement and participate in progressive renal fibrosis. Our study clarified the nephron segment-specific cyst profile related to EMT in PCK rats. EMT may play a key role in polycystic kidney disease.

Kugita M, Nishii K, Morita M, Yoshihara D, Kowa-Sugiyama H, Yamada K, Yamaguchi T, Wallace DP, Calvet JP, Kurahashi H, Nagao S. Global gene expression profiling in early-stage polycystic kidney disease in the Han: SPRD Cy rat identifies a role for RXR signaling. Am J Physiol Renal Physiol 300: F177-F188, 2011. First published October 6, 2010; doi:10.1152/ajprenal.00470.2010.-Han: SPRD Cy is a spontaneous rat model of polycystic kidney disease (PKD) caused by a missense mutation in Pkdr1. Cystogenesis in this model is not clearly understood. In the current study, we performed global gene expression profiling in early-stage PKD cyst development in Cy/Cy kidneys and normal (+/+) kidneys at 3 and 7 days of postnatal age. Expression profiles were determined by microarray analysis, followed by validation with real-time RT-PCR. Genes were selected with over 1.5-fold expression changes compared with age-matched +/+ kidneys for canonical pathway analysis. We found nine pathways in common between 3- and 7-day Cy/Cy kidneys. Three significantly changed pathways were designated "Vitamin D Receptor (VDR)/Retinoid X Receptor (RXR) Activation," " LPS/IL-1-Mediated Inhibition of RXR Function," and " Liver X Receptor (LXR)/RXR Activation." These results suggest that RXR-mediated signaling is significantly altered in developing kidneys with mutated Pkdr1. In gene ontology analysis, the functions of these RXR-related genes were found to be involved in regulating cell proliferation and organ morphogenesis. With real-time RT-PCR analysis, the upregulation of Ptx2, Alox15b, OSP, and PCNA, major markers of cell proliferation associated with the RXR pathway, were confirmed in 3- and 7-day Cy/Cy kidneys compared with 3-day +/+ kidneys. The increased RXR protein was observed in both the nucleus and cytoplasm of cystic epithelial cells in early-stage Cy/Cy kidneys, and the RXR-positive cells were strongly positive for PCNA staining. Taken together, cell proliferation and organ morphogenesis signals transduced by RXR-mediated pathways may have important roles for cystogenesis in early-stage PKD in this Pkdr1-mutated Cy rat.

振盪刺激は閉経後に起こる骨密度低下を防止する効果的な物理療法と考えられている。大腿骨を補強する筋群は、振盪刺激により骨に間接的影響を与えている。この刺激は下半身の筋を中心に等尺性運動もしくは等張性運動を強制的に行う。本研究は下半身の運動に重要とされ、またインナーマッスルとしてよく知られている大腰筋について解析を行った。筋の発生や再生および分化に影響を与える特異的なタンパク質の発現量をWestern blot法を用いて組織学的解析と合わせて比較検討を行った。実験は、ICRマウスを使用し、卵巣摘出した群と正常群の2群に分類し、それぞれの群に対して、刺激を行った群と行わない群に区分した(卵巣摘出/振盪:+/+、+/-、-/+、-/-)、計4群に対して実験を行った。振盪刺激を10週間継続した後に大腰筋を採取し、起始側と停止側の2つの領域を解析するため2等分した。組織学的解析は、筋線維横断面をH.E.染色し、筋線維の短径と線維数を計測した。組織学的解析において、振盪刺激による筋線維の肥大は、筋線維短径の計測により停止側で確認された。しかし、筋線維数の変化については顕著な違いは認められなかった。筋の肥大を促進するタンパク質であるgrowth differentiation factor 8(GDF-8)と発生・分化に関与するmyogenic factor 5(Myf-5)、myogenic factor 6(Myf-6)のタンパク質発現量は、刺激を行った群と行わなかった群において行った群の停止側に増加傾向を示した。大腰筋のような二関節筋の働きをする筋において起始・停止部分で筋肥大ならびに発生や分化に部位差の相違が認められた。本研究において大腰筋の停止部で刺激による部位差が顕著であったことから振盪刺激が姿勢安定による転倒予防と下半身、特に大腿部における骨を補強する効果的な物理療法になり得ると考える。(著者抄録)