"In vivo cryotechnique" for paradigm shift to "living morphology" of animal organs

The morphological study has been one of the major approaches in medical and biological fields. For the last century, the conventional chemical fixation and alcohol dehydration were commonly used as an easy preparation method, but it was frequently pointed out that they usually yield many structural artifacts during their preparation processes. Although both conventional quick-freezing and high-pressure freezing methods, by which animal tissues are resected and frozen for physical fixation,can reduce such structural artifacts, the tissues have to be removed from living animal organs for the freezing. Therefore, such specimens are inevitably exposed to noxious stresses of anoxia and ischemia, exhibiting only dead morphological states of animal tissues without blood circulation. To the contrary, our "in vivo cryotechnique", by which all cells and tissues in animal bodies are cryofixed in vivo, can prevent such artifacts of resected specimens. By means of the cryotechnique, it is now possible to reveal the in vivo morphology of cells and tissues in living animal organs. Actually, it has been already applied to several animal organs, such as kidney, liver, intestine, cerebellum, eye ball, blood vessel, and joint cartilage, and brought new morphological findings, reflecting their physiological significance, which had been difficult to demonstrate by the conventional preparation methods. Moreover, its application to immunohistochemistry has also revealed more precise immunolocalizations of dynamically changing molecules in living animal organs, easily translocated by ischemic stresses and anoxia caused during the tissue resection. The "in vivo cryotechnique" allows us to perform novel morphological investigations of "living" morphological states, and develops new medical and biological fields with "living morphology" during this 21st century.Biomedical Reviews 2004; 15: 1-19

Ultrastructure of glomerular basement membrane by quick-freeze and deep-etch methods

Ultrastructure of glomerular basement membrane by quick-freeze and deep-etch methods. The glomerular basement membrane of rat kidneys were three-dimensionally observed by quick-freeze and deep-etch replica methods at high resolution. The middle layer (lamina densa) was composed of 6 to 10nm fibrils which formed a meshwork structure. The space between the fibrils had polygonal shape. The average long dimension of the space between fibrils was 17nm and the short one was 13nm. At the outer layer (lamina rara externa), fibrils connected podocytes perpendicularly with the meshwork of the middle layer. At the inner layer (lamina rara interna), similar perpendicular fibrils also connected endothelial cells with the meshwork of the middle layer. This is the first report to visualize the three-dimensional meshwork structure of the middle layer (the lamina densa) in situ. The function of anchoring podocytes to the lamina densa was suggested in the perpendicularly arranged fibrils of the outer layer. The quick-freeze and deep-etch method is useful in analyzing filamentous ultrastructure in glomeruli, and will be applied to clarifying pathological ultrastructure in kidney diseases

Histological Study and LYVE-1 Immunolocalization of Mouse Mesenteric Lymph Nodes with “In Vivo Cryotechnique”

The “in vivo cryotechnique” (IVCT) is a powerful tool to directly freeze living animal organs in order to maintain biological components in frozen tissues, reflecting their native states. In this study, mesenteric lymph nodes of living mice were directly frozen with IVCT, and we did morphological studies and immunohistochemical analyses on a hyaluronic acid receptor, LYVE-1. In lymph nodes, widely open lymphatic sinuses were observed, and many lymphocytes adhered to inner endothelial cells along subcapsular sinuses. The LYVE-1 was clearly immunolocalized at inner endothelial cells of subcapsular sinuses, as well as those of medullary sinuses. Conventional pre-embedding electron microscopy also showed LYVE-1 immunolocalization along both the apical and basal sides of cell membranes of inner endothelial cells. By triple-immunostaining for LYVE-1, smooth muscle actin, and type IV collagen, the LYVE-1 was immunolocalized only in the inner endothelial cells, but not in outer ones which were surrounded by collagen matrix and smooth muscle cells. Thus, the functional morphology of lymph nodes in vivo was demonstrated and LYVE-1 immunolocalization in inner endothelial cells of subcapsular sinuses suggests hyaluronic acid incorporation into lymph node parenchyma

PURIFICATION AND PROPERTIES OF AN AZO-REDUCTASE FROM BACILLUS SP.

Joint Research on Environmental Science and Technology for the Eart

Improved utilization of wireless lan by planning the placement of wireless access points

スマートフォンやiPadに代表されるタブレット型端末の登場で、鳥取大学においても無線LANの需要が増大している。この需要を満たすため、既存の無線APを再配置することで無線LANのカバレッジエリアの拡大を検討している。無線AP の再配置には、配置前のシミュレーションの実行だけでなく、配置後にサイトサーベイを実施し、シミュレーション結果との比較を元に再設置箇所を検討する必要がある。本取り組みでは、シミュレーションの精度を向上させるため、配線工事を伴わない範囲で無線AP の配置を見直した。再配置と同様に、本取り組みでもシミュレーションとサイトサーベイの結果を比較している。使用したシミュレーションソフトウェア、AirMagnet Planner は2次元平面を対象としおり、各階に設置した無線AP だけを対象としたサイトサーベイの結果と比較すると、適切にシミュレーションができることが分かった。しかしながら、実際には上下階に設置した無線APからの電波が大きく影響するため、作業者による予測にてこの問題に対処した。本作業による知見はそのまま再配置作業に適用できるため、有益な結果が得られたと考えている

Selective Oxidation of Benzaldehyde Derivatives on TiO2 Photocatalysts Modified with Fluorocarbon Group

Fluorocarbon groups were introduced onto surfaces of SiO2-covered TiO2 particles (SiO2–TiO2). Oxidation of pentafuluorobenzaldehyde on the surface modified TiO2 powders proceeded much efficiently than that on SiO2-covered TiO2 particles without surface modification. In addition, no enhancement of activity level of surface-modified SiO2–TiO2 for oxidation of benzaldehyde was observed. The enhancement of the surface-modified SiO2–TiO2 is due to the interaction of F atoms between the substrate and fluorocarbon groups introduced on SiO2–TiO2

Ultrahigh-sensitivity optical power monitor for Si photonic circuits

A phototransistor is a promising candidate as an optical power monitor in Si photonic circuits since the internal gain of photocurrent enables high sensitivity. However, state-of-the-art waveguide-coupled phototransistors suffer from a responsivity of lower than $10^3$ A/W, which is insufficient for detecting very low power light. Here, we present a waveguide-coupled phototransistor consisting of an InGaAs ultrathin channel on a Si waveguide working as a gate electrode to increase the responsivity. The Si waveguide gate underneath the InGaAs ultrathin channel enables the effective control of transistor current without optical absorption by the gate metal. As a result, our phototransistor achieved the highest responsivity of approximately $10^6$ A/W among the waveguide-coupled phototransistors, allowing us to detect light of 621 fW propagating in the Si waveguide. The high responsivity and the reasonable response time of approximately 100 $\mu$s make our phototransistor promising as an effective optical power monitor in Si photonics circuits