Biomedical subjects

N Ohshima

Publications and source records attributed to N Ohshima.

116 records · Page 7Linked to original sources

PubMedDate not supplied

Morphological changes of endothelial cells after exposure to fluid-imposed shear stress: differential responses induced by extracellular matrices.

Effects of extracellular matrices (ECMs) and fluid-imposed shear stress on the cell shape and the cytoskeletal structure of microfilaments were studied in cultured porcine aortic endothelial cells (PAECs). The PAECs were cultured until confluent on non-coated or on ECM-coated glass coverslips. The components of ECM used were type IV collagen, heparan sulfate, chondroitin sulfate and dermatan sulfate. The PAECs cultured on the mixed ECMs showed marked elongation and segmental orientation with randomly distributed cell axis even under a no-flow static condition, and the microfilaments were mostly observed in parallel with the cell axis. After shear flow exposure (2 Pa, 24-48 hrs), the PAECs on non-coated glass were significantly elongated and oriented to the flow direction, however the PAECs on ECM-coated glass showed more retarded responses than the ones on non-coated glass, indicating that the anchorage to the substrate was enhanced by ECMs. The stress fibers were reorganized in accordance with the cell shape and oriented to the flow direction. These findings suggest that ECM may act together with shear stress to modify and maintain the endothelial cell configuration.

Animals↗

PubMedDate not supplied

Flow-induced changes in shape and cytoskeletal structure of vascular endothelial cells.

Changes in shape and cytoskeletal structure of vascular endothelial cells induced by fluid-imposed shear stress were studied in vivo and in vitro. In in vivo experiments, aortic tissue specimens including the flow dividers of the branching of the left subclavian artery and the aortic intercostal ostium were obtained and their endothelial cell shapes were observed using the scanning electron microscope. It was found that the shape and orientation of endothelial cells were strongly affected by blood flow conditions. In in vitro cell culture experiments, porcine aortic endothelial cells were cultured on glass coverslips and extracellular matrix coated (ECM coated) glass coverslips and exposed to shear stress using a parallel plate flow chamber. When we applied a shear stress of 2 Pa for 24 hrs, the rearrangement of F-actin filaments occurred within 3 hrs and preceded the cell shape change in the early stage after shear exposure. The endothelial cells on ECM-coated coverslips exhibited more elongated cell shapes even under no-flow conditions. After exposure to shear stress, the endothelial cells on ECM-coated glass showed more retarded elongation and orientation to the direction of flow than those on no-coated glass, suggesting that the anchorage to the substrate was enhanced by ECMs.

Actins↗

PubMedDate not supplied

Insulin increases blood flow rate in the microvasculature of cremaster muscle of the anesthetized rats.

The hemodynamic actions of insulin in skeletal muscle microvasculature are not yet well elucidated. In the present study, we investigated the effects of systemic insulin injection on arteriole and capillary diameter and blood flow rate in rat cremaster muscle, using intravital real-time confocal laser-scanning microscope system in combination with selective fluorescent labeling. Subcutaneous insulin injecbon (1 U/kg) significantly increased serum insulin levels at 15 minutes as compared with saline injection. At 15 and 30 minutes after insulin injection, blood glucose levels were significantly lower compared to saline injected controls. Arteriolar diameter was significantly increased at 15 and 30 minutes by insulin. Arteriolar erythrocyte flow velocity was significantly increased at 15 and 30 minutes. In addition, capillary erythrocyte flow velocity was increased at 15 and 30 minutes. These results demonstrated that calculated blood flow rates in capillary and arteriole increased after insulin injection.

Anesthesia↗

PubMedDate not supplied

Effects of intra-arterial administration of prostaglandin E1 on rat cremaster muscle microcirculation.

In plastic and reconstructive surgery, postoperative drug therapy with prostaglandin E1 (PGE1) has been widely used to prevent flap necrosis and to extend flap surviving area. In the present study, we assessed the effects of intra-arterial administration of PGE1 on microcirculation. The left cremaster muscle of male Wistar rats were used to measure microcirculatory hemodynamic parameters. The values of internal vessel diameter and erythrocyte velocity were measured by using the confocal laser-scanning microscope (CLSM) system and fluorescent dyes. The blood flow rate was calculated from measured internal vessel diameter and erythrocyte velocity. Internal vessel diameter and flowing erythrocytes were satisfactorily visualized by using the CLSM system. The blood flow rate of arteriole, venule and capillary were dose dependently increased by the intra-arterial administration of PGE1 from the minimum dose of 0.01 ng/kg/min. It is suggested that the intra-arterial administration of PGE1 is a more effective way of postoperative drug therapy than intravenous injection for flap surgery.

Alprostadil↗

PubMedDate not supplied

Vascular endothelial growth factor (VEGF) expression regulates angiogenesis accompanying tumor growth in a peritoneal disseminated tumor model.

Quantitative analysis of the process of tumor angiogenesis was performed in a new animal model of tumor microcirculation, in which colon carcinoma cells were inoculated into the peritoneal cavity of rats. Time-dependent changes in the microvascular architecture of mesenteric microvessels of tumor-bearing rats were visualized using an intravital microscope. Simultaneously, the expression of vascular endothelial growth factor (VEGF) by the tumor cells and VEGF secretion into ascites were analyzed. The results showed that VEGF increases microvascular permeability and stimulates the growth of microvessels into the tumor and that the spatial and temporal concentration of VEGF is strongly correlated. Such a correlation was stronger in the early angiogenic stages of tumor growth than in the subsequently occurring multiple metastatic stage, when VEGF was still observed at a high level in tumor surroundings. Thus, VEGF is suggested to be primarily involved in the pathophysiological control of angiogenesis accompanying tumor progression.

Animals↗

PubMedDate not supplied

Emigration of activated leukocytes augments transvascular permeability in mesenteric venules of rat.

Effects of leukocyte adhesion and emigration on the microvascular permeability were analyzed by the combined use of high resolution transilluminated intravital microscopy and the epiilluminated fluorescent tracer imaging. After stimulating leukocytes by topical application of PAF-LPS or fMLP solution on the mesentery of a rat, a dynamic process of leukocyte emigration was visualized under high resolution transilluminated microscopic observation. When considerable emigration of leukocytes was observed, the same microvasculature was subjected to a permeability study to visualize the diffusional process of the FITC-labeled macromolecules under an epiilluminated fluorescent microscope. Dye diffusion was accelerated in the PAF-LPS or fMLP-treated group, and also a distinctly spotty leakage was observed in venules where successive adhesion and emigration of leukocytes were observed.

Animals↗

PubMedDate not supplied

A high density culture of hepatocytes using a reticulated polyvinyl formol resin.

To enable high density culture of hepatocytes to be used as a hybrid artificial liver support or bioreactor system, collagen coated reticulated polyvinyl formal (PVF) resin (a filter material with a porosity of more than 80%) was used for the primary culture of hepatocytes. Stationary and perfusion culture experiments using PVF resin and monolayer culture were performed as control experiments. Due to the porous structure of the substrate material, hepatocytes were able to penetrate the reticulated pores of the PVF resin, and adhere to and spread on its surface. The densities of hepatocytes attained with PVF were about 10 times as high as those in the monolayer culture using conventional collagen coated Petri dishes. Hepatocytes immobilized in the PVF resin showed viability, as assessed by glutamic pyruvic transaminase (GPT) activity in the medium. Perfusion culture with PVF resin showed stable, high level metabolism, ammonium removal, and urea secretion comparable to the monolayer culture. It is concluded that perfusion culture with PVF resin is useful in attaining a high density culture of hepatocytes.

Animals↗

PubMedDate not supplied

Tissue distribution and metabolism of amitriptyline after repeated administration in rats.

Plasma concentration, tissue distribution, and metabolism of amitriptyline (AMI) in rats pretreated with AMI (20 mg/kg/day, ip dose, for 7 days; treated) were compared with control rats. Plasma concentrations of AMI after intravenous administration (2 and 10 mg/kg) to the treated rat were significantly higher than those to the control rat in both doses. The difference in the plasma concentration between both groups may be caused by a change of tissue distribution of AMI, because the blood cell-to-plasma concentration ratio and the tissue-to-blood concentration ratio values for various tissues in the treated rat were smaller than those in the control, respectively. The plasma unbound fraction of AMI in the treated rat was significantly smaller (p < 0.05). alpha 1-Acid glycoprotein concentration in plasma of the treated rat was approximately twice that in the control rat. These results suggest that the decrease of tissue distribution of AMI in the treated rat may be caused by the decrease in the plasma unbound fraction of AMI with the increase of alpha 1-acid glycoprotein in plasma. The area under the plasma concentration-time curve for AMI and its main metabolite, nortriptyline, in the treated rat after intraportal administration of AMI was 1/3 and 3-fold those in the control rats, respectively. On the other hand, the hepatic intrinsic clearance (CLH,Int) of the unbound drug in the treated rat was approximately twice that of the control, suggesting that the increase of the (CLH,Int) by repeated administration of AMI may result in the induction of oxidative metabolism.

Amitriptyline↗