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Featured researches published by Osamu Shimada.


Journal of Histochemistry and Cytochemistry | 1998

Detection of Deoxyribonuclease I Along the Secretory Pathway in Paneth Cells of Human Small Intestine

Osamu Shimada; Harunori Ishikawa; Hisami Tosaka-Shimada; Toshihiro Yasuda; Koichiro Kishi; Shosuke Suzuki

The expression and distribution of deoxyribonuclease I (DNase I) in human duodenum, jejunum and ileum were examined by DNase I activity assay and the reverse transcriptase-polymerase chain reaction (RT-PCR), immunofluorescence, in situ hybridization, and immunocytochemical ultrastructural analyses. High levels of DNase I were detected in the cytoplasm of Paneth cells in human small intestine. A tissue homogenate fraction rich in Paneth cells showed strong DNase I-specific enzymatic activity. Immunofluorescence analysis using several specific anti-human DNase I antibodies showed very strong immunoreactivity in the cytoplasm of every Paneth cell. In situ hybridization demonstrated high levels of DNase I mRNA in Paneth cells. Immunogold electron microscopy revealed gold particles localized along the secretory pathway, with the exocrine secretory granules mostly labeled. Our findings strongly suggest that Paneth cells synthesize and secrete DNase I into the intestinal lumen.


Journal of Histochemistry and Cytochemistry | 2003

Localization of VIP36 in the Post-Golgi Secretory Pathway Also of Rat Parotid Acinar Cells

Osamu Shimada; Sayuri Hara-Kuge; Katsuko Yamashita; Hisami Tosaka-Shimada; Li Yanchao; Li Einan; Saoko Atsumi; Harunori Ishikawa

VIP36 (36-kD vesicular integral membrane protein), originally purified from Madin-Darby canine kidney (MDCK) epithelial cells, belongs to a family of animal lectins and may act as a cargo receptor. To understand its role in secretory processes, we performed morphological analysis of the rat parotid gland. Immunoelectron microscopy provided evidence that endogenous VIP36 is localized in the trans-Golgi network, on immature granules, and on mature secretory granules in acinar cells. Double-staining immunofluorescence experiments confirmed that VIP36 and amylase co-localized in the apical regions of the acinar cells. This is the first study to demonstrate that endogenous VIP36 is involved in the post-Golgi secretory pathway, suggesting that VIP36 plays a role in trafficking and sorting of secretory and/or membrane proteins during granule formation.


Cell and Tissue Research | 1990

Morphological effects of somatostatin on rat somatotrophs previously activated by growth hormone-releasing factor

Osamu Shimada; Hisami Tosaka-Shimada; Harunori Ishikawa

SummaryCorrelative morphological and physiological analysis was carried out in order to clarify the role of somatostatin in the inhibition of the secretion of growth hormone (GH) from somatotrophs of the rat anterior pituitary gland in vivo. Transmission electron microscopy combined with immunogold labelling showed an increased number of exocytotic GH-containing secretory granules in somatotrophs fixed between 2 and 10 min after injection of GH-releasing factor (GRF). Injection of GRF also induced the appearance of immunopositive material in cisternae of the Golgi apparatus, many coated vesicles and multivesicular bodies. Microtubules were observed more frequently throughout the cytoplasm, particularly in and near the Golgi region. At 2 and 10 min after injection of somatostatin (SRIF), both the number of exocytotic figures in the somatotrophs previously stimulated by GRF and the amount of radioimmunoassayable GH in the plasma were clearly decreased. Undulation of the plasma membrane (PM) induced by GRF rapidly disappeared, and the number of granules just beneath the plasma membrane was significantly reduced. After injection of SRIF, parallel bundles of microfilaments were often observed in the space between the granules and the plasma membrane. SRIF did not cause a noticeable decrease in the amount of immunopositive material, coated vesicles and multivesicular bodies in the Golgi areas or any significant changes in the distribution of microtubules. SRIF therefore appears to inhibit hormone release mainly at the level of the plasma membrane, probably through changes in the distribution of microfilaments.


Glycobiology | 2004

The binding of VIP36 and α-amylase in the secretory vesicles via high-mannose type glycans

Sayuri Hara-Kuge; Akira Seko; Osamu Shimada; Hisami Tosaka-Shimada; Katsuko Yamashita


Glycobiology | 2007

Stable interaction of the cargo receptor VIP36 with molecular chaperone BiP

Daisuke Nawa; Osamu Shimada; Norihito Kawasaki; Naoki Matsumoto; Kazuo Yamamoto


Endocrinology | 1989

Morphological analysis of growth hormone release from rat somatotrophs into blood vessels by immunogold electron microscopy.

Osamu Shimada; Hisami Tosaka-Shimada


Archives of Histology and Cytology | 1989

Somatostatin-containing neurons in the mouse brain: An immunohistochemical study and comparison with the rat brain.

Osamu Shimada; Harunori Ishikawa


Cell Structure and Function | 2003

Clusters of VIP36-Positive Vesicles between Endoplasmic Reticulum and Golgi Apparatus in GH3 Cells

Osamu Shimada; Sayuri Hara-Kuge; Katsuko Yamashita; Hisami Tosaka-Shimada; Li Yanchao; Li Yongnan; Saoko Atsumi; Harunori Ishikawa


Cell Structure and Function | 1999

Exocytotic secretion of toxins from macrophages infected with Escherichia coli O157.

Osamu Shimada; Harunori Ishikawa; Hisami Tosaka-Shimada; Saoko Atsumi


Cell Structure and Function | 1998

Detection of Deoxyribonuclease I in a Hormone-secretory Pathway of Pituitary Cells in Humans and Rats

Osamu Shimada; Shosuke Suzuki; Hisami Tosaka-Shimada; Harunori Ishikawa

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Saoko Atsumi

University of Yamanashi

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Katsuko Yamashita

Tokyo Institute of Technology

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