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112 results on '"Ito, Jin-ichi"'

43. Differential Generation of High-Density Lipoprotein by Endogenous andExogenous Apolipoproteins in Cultured Fetal Rat Astrocytes.

Author

Ito, Jin-ichi, Zhang, Li-Yong, Asai, Michiyo, and Yokoyama, Shinji

Subjects
*HIGH density lipoproteins, *APOLIPOPROTEINS, *ASTROCYTES, *RATS, *SCIENTIFIC experimentation
Abstract

Abstract: Most peripheral cells generate cholesterol-rich high-density lipoprotein (HDL) with exogenous apolipoprotein as one of the mechanisms for the maintenance of cellular cholesterol homeostasis. Astrocytes isolated from fetal rat brain showed a unique behavior in this reaction. Consistent with previous findings, the astrocytes synthesized apolipoprotein (apo) E and generated cholesterol-rich pre-beta-HDL-like lipoprotein with this apoE, and cellular cholesterol and phospholipids. When exogenous apoA-I and E were added to the medium, they caused generation of additional HDL with cellular phospholipid. It is interesting that this additional part was very poor in cholesterol except for the generation of relatively cholesterol-rich HDL only in the initial few hours of the incubation. The mobilization of intracellular cholesterol for this reaction was also very limited, reflecting the poor cholesterol incorporation into the HDL Thus, the results demonstrated a unique profile of HDL generation and cholesterol efflux by apolipoproteins in rat astrocytes, with endogenous apoE producing cholesterol-rich HDL and exogenous apolipoproteins producing cholesterolpoor HDL These lipoproteins may play differential roles in cholesterol transport in the CNS. Key Words: High-density lipoprotein--Apolipoproteins--Cholesterol--Astrocytes--Rat. J. Neurochem. 72, 2362-2369 (1999). [ABSTRACT FROM AUTHOR]

Published
1999
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46. Astrocytes produce and secrete FGF-1, which promotes the production of apoE-HDL in a manner of autocrine action

Author

Ito, Jin-ichi, Nagayasu, Yuko, Lu, Rui, Kheirollah, Alireza, Hayashi, Michi, and Yokoyama, Shinji

Abstract

The astrocytes prepared by 1 week secondary culture after 1 month primary culture of rat brain cells (M/W cells) synthesized and secreted apolipoprotein E (apoE) and cholesterol more than the astrocytes prepared by conventional 1 week primary and 1 week secondary culture (W/W cells) (Ueno, S., J. Ito, Y. Nagayasu, T. Furukawa, and S. Yokoyama. 2002. An acidic fibroblast growth factor-like factor secreted into the brain cell culture medium upregulates apoE synthesis, HDL secretion and cholesterol metabolism in rat astrocytes. Biochim. Biophys. Acta.1589:261–272). M/W cells also highly expressed fibroblast growth factor-1 (FGF-1) mRNA. FGF-1 was identified in the cell lysate of both cell types, but M/W cells released more of it into the medium. Immunostaining of FGF-1 and apoE revealed that both localized in the cells that produce glial fibrillary acidic protein. The conditioned media of M/W cells and FGF-1 stimulated W/W cells to release apoE and cholesterol to generate more HDL. Pretreatment with a goat anti-FGF-1 antibody or heparin depleted the stimulatory activity of M/W cell-conditioned medium. The presence of the anti-FGF-1 antibody in the medium suppressed apoE secretion by M/W cells. Differential inhibition of signaling pathways suggested that FGF-1 stimulates apoE synthesis via the phosphoinositide 3-OH kinase for PI3K/Akt pathway. Thus, astrocytes release FGF-1, which promotes apoE-HDL production by an autocrine mechanism.

Published
2005
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47. An Application of Short Bearing Theory to Dynamic Characteristic Problems of Turbulent Journal Bearings

Author

Hashimoto, Hiromu, Wada, Sanae, and Ito, Jin-ichi

Abstract

The dynamic characteristic problems of turbulent journal bearings are theoretically analyzed. The oil film forces considering the turbulent effects are analytically obtained under the short bearing assumption. The linearized stability analysis is developed for a perfectly rigid rotor supported horizontally in the two identical aligned oil film journal bearings and the whirl onset velocities for rotor-bearing systems are determined for various Reynolds numbers. In addition, the nonlinear equations of motion for rotor-bearing systems are solved by the improved Euler’s method and the journal center trajectories are examined for both cases with and without out-of-balance forces. The results obtained from the short bearing theory are compared with those from the finite bearing theory for the length-to-diameter ratio λ = 0.25 and 0.5. It is found that the turbulence has significant effects on the dynamic behavior of rotor-bearing systems and the short bearing theory has an advantage of reducing a computation time required for the calculation of journal center trajectories with an acceptable accuracy.

Published
1987
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