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Biomedical subjects

S Murota

Publications and source records attributed to S Murota.

At least 127 records · Page 7Linked to original sources
PubMed1991

Angiogenic factor of a rat mammary tumor cell line (RMT-1) (I). Secretion of two distinct angiogenic factors into serum-free conditioned medium by RMT-1 cells.

Serum-free conditioned medium of a rat mammary tumor cell line RMT-1, established from a rat mammary carcinoma induced by 7,12-dimethylbenz[a]anthracene (DMBA), produced the complete angiogenic response in both rabbit cornea and chick embryo chorioallantoic membrane assays. The angiogenic activity in the RMT-1 conditioned medium was separated into two fractions on a column of heparin-Sepharose; one was eluted with 0.1 M NaCl and the other with 0.5 M NaCl, which are referred to hereafter as rAF-1 and rAF-2, respectively. These two angiogenic factors were further purified separately by FPLC on a Superose 12 column. The partially purified rAF-2 had an apparent Mr of 30,000-50,000 and seemed to exhibit mitogenic activity toward Balb/c 3T3 cells, while the partially purified rAF-1, with an apparent Mr of 10,000-30,000 did not have a mitogenic effect on these cells. Both rAF-1 and rAF-2 were resistant to heat and acid treatment, and exhibited trypsin sensitivity, suggesting that they are heat and acid stable peptides. The two angiogenic factors did not stimulate the proliferation of cultured vascular endothelial cells. These results suggest that RMT-1 secretes two distinct angiogenic factors into the medium and that these two secretable angiogenic factors participate cooperatively in the induction of the angiogenic response produced by a DMBA-induced rat mammary tumor in vivo.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1991

Involvement of adhesion molecules (CD11a-ICAM-1) in vascular endothelial cell injury elicited by PMA-stimulated neutrophils.

Protective effect of anti-CD11a and anti-ICAM-1 antibodies on the cytotoxicity induced by PMA-stimulated neutrophils was studied using cultured endothelial cells isolated from bovine carotid artery. Anti-CD11a antibody and anti-ICAM-1 antibody inhibited the endothelial cell injury induced by the activated neutrophils in a dose dependent manner. On the other hand, both antibodies themselves had no effect on either the luminol chemiluminescence released out of the activated neutrophils or the adhesion of the neutrophils to the endothelial cell monolayer. These data suggest that these adhesion molecules play some important roles in the vascular endothelial cell injury elicited by activated neutrophils.

Animals↗
PubMed1991

Astrocytes are responsive to endothelium-derived relaxing factor (EDRF).

The effects of endothelium-derived relaxing factor (EDRF) and sodium nitroprusside (SNP), which produces nitric oxide (NO) spontaneously, on cultured astrocytes prepared from cerebra of rat embryos were examined. EDRF produced by vascular endothelial cells in response to bradykinin stimulation, caused a significant rise in cyclic GMP levels of astrocytes. SNP also increased cyclic GMP levels of astrocytes in a dose-dependent way. These results revealed for the first time unambiguously that astrocytes are responsive to EDRF.

1-Methyl-3-isobutylxanthine↗
PubMed1991

Eicosapentaenoic acid inhibits tube formation of vascular endothelial cells in vitro.

We previously have described a quantitative angiogenesis in vitro model, in which endothelial cells are cultured between two layers of type I collagen gel and become organized into tube-like structures. Using this model, the effect of eicosapentaenoic acid (20:5n-3) on tube formation was investigated. When the endothelial cells isolated from bovine carotid artery were treated for 2 days with 5 micrograms/mL of arachidonic acid (20:4n-6), eicosapentaenoic acid or docosahexaenoic acid (22:6n-3), these polyunsaturated fatty acids were extensively incorporated into cellular phospholipids. The context of arachidonic, eicosapentaenoic and docosahexaenoic acid increased from 9.58% to 23.29%, from 0.98% to 11.76% and from 6.88% to 18.40%, respectively. When the eicosapentaenoic acid-treated cells were cultured between collagen gels, the tube-forming ability of the cell was markedly inhibited. The inhibition was dose-dependent between 1.0 and 5.0 micrograms/mL of eicosapentaenoic acid. At 5.0 micrograms/mL of eicosapentaenoic acid the inhibition reached 76%. By contrast, arachidonic acid increased tube formation, and docosahexaenoic acid had no effect. To elucidate the mechanism of eicosapentaenoic acid induced inhibition of in vitro tube formation, we examined the effect of the acid on the proliferation of endothelial cells. Eicosapentaenoic acid at any dose (less than 5.0 micrograms/mL) had no effect on the proliferation of endothelial cells cultured on plastic plates without collagen gel. However, when the cells were cultured between collagen gels, eicosapentaenoic acid inhibited cell growth in a dose-dependent manner with maximum inhibition being observed at 2.5 micrograms/mL. These data suggest that eicosapentaenoic acid suppresses tube formation of endothelial cells,at least in part, via its inhibitory effect on cellular proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effects of glucose on migration, proliferation and tube formation by vascular endothelial cells.

In order to elucidate the association between hyperglycemia and the vascular complications of diabetes, the effects of high glucose concentrations on the migration, proliferation and tube formation of bovine carotid artery endothelial cells were investigated. Cells treated with 16.7 and 33.3 mM glucose for 6 days showed 1.69- and 1.75-fold increase in serum-induced migration compared with cells treated with 5.6 mM glucose (p less than 0.05). The effect of glucose on cell proliferation was affected by serum concentration. When this was below 0.5%, a high glucose concentration stimulated cell growth to a maximum of 1.73 times that at a serum concentration of 0.05% (p less than 0.01) whereas at a serum concentration of 10%, growth was inhibited (p less than 0.05). Tube formation was studied by culturing the cells between two layers of collagen gel. Ultrastructurally, tubular structures were composed of one to several endothelial cells containing pinocytotic vesicles and cytoplasmic projections, and linked by junctional complexes. A basal lamina-like structure surrounded the abluminal surface. Treatment of the cells with 16.7 and 27.8 mM glucose for 4 days stimulated tubular elongation 1.85 and 1.71 times, respectively (p less than 0.01). Other osmogenic molecules such as mannitol and sucrose did not affect tube formation. These data imply that high glucose concentrations mimicking diabetic hyperglycemia may not inhibit the repair of endothelial injury and could act as a stimulator of neovascularization.

Animals↗
PubMed1991

Enhancement of migration in bovine endothelial cells by eicosapentaenoic acid pretreatment.

It has been recognized that endothelial cell migration is an important process in the regeneration of injury in blood vessels. In this study, we examined the effects of polyunsaturated fatty acids on the migration of cultured endothelial cells using a modified Boyden chamber. When endothelial cells isolated from bovine carotid artery were pretreated for 2 days with 5 micrograms/ml of either arachidonic acid, eicosapentaenoic acid or docosahexaenoic acid, every polyunsaturated fatty acid was incorporated substantially into cellular phospholipids. The content of arachidonic acid increased from 9.27 to 23.9% by the arachidonic acid pretreatment, and that of eicosapentaenoic acid and docosahexaenoic acid increased from 9.57 to 11.85% by the eicosapentaenoic acid pretreatment and from 5.56 to 18.40% by the docosahexaenoic acid pretreatment, respectively. Pretreatment of the cells with 0.5-5.0 micrograms/ml of eicosapentaenoic acid resulted in a dose-dependent increase in endothelial migration in response to fetal bovine serum. In contrast, pretreatment of the cells with arachidonic acid and docosahexaenoic acid had no effects on the cell migration. If eicosapentaenoic acid, however, was added directly to the migration assay system instead of the pretreatment, it did not show a profile of chemotactic factor. The eicosapentaenoic acid pretreatment also potentiated cell migration activity in response to several other chemotactic factors such as basic fibroblast growth factor, tumor necrosis factor-alpha and leukotriene C4. The effect of eicosapentaenoic acid on porcine smooth muscle cell migration was also examined. Although eicosapentaenoic acid was similarly incorporated into cellular phospholipids of smooth muscle cells by the pretreatment for 2 days, no stimulative effect was observed in the migration of smooth muscle cells at any doses (0.5-5.0 microns/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Cytoprotective effect of reduced glutathione in arsenical-induced endothelial cell injury.

The effect of four arsenic compounds on cultured endothelial cell isolated from bovine carotid arteries was studied. Only trivalent arsenicals (arsenic trioxide and sodium m-arsenite), but not pentavalent arsenicals (arsenic acid and p-arsenilic acid), induced significant cell injury. Since the intracellular reduced glutathione (GSH) plays an important role in detoxication in mammalian cells, its effect on arsenical-induced cell injury was then studied. Pretreatment of cells with 500 microM GSH not only resulted in several-fold increase in the intracellular level of GSH but also effectively protected them against the injury caused by arsenic trioxide. After a pretreatment of cells with GSH for 3 h, the intracellular GSH reached a plateau. A longer pretreatment for 24 h still kept GSH at a very significant high level. The cell injury induced by arsenic trioxide was protected by GSH, and then cellular biosynthesis of PGI2 in culture was also increased. The cytoprotective effect and the stimulatory effect on PGI2 production, where both were dose-dependent on GSH, were in a strict reverse relationship. Aspirin treatment inhibited the PGI2 biosynthesis induced by GSH in the arsenic trioxide-induced cell injury, and significantly reduced the cytoprotective effect induced by GSH. These results suggest that the marked stimulation of endogenous PGI2 biosynthesis by GSH is the mechanism of the latter's cytoprotective effect on arsenic trioxide-induced endothelial cell injury.

Animals↗
PubMed1991

Inhibition of PGE2 production in macrophages from vitamin E-treated rats.

Rat peritoneal macrophages from vitamin E-treated rats (5 mg per rat for 6 successive days) contained 403.3 +/- 90.7 ng alpha-tocopherol/10(6) cells, whereas control macrophages contained 1.2 +/- 0.4 ng. PGE2 production in the macrophages from vitamin E-treated rats was significantly suppressed when stimulated with PMA and calcium ionophore A23187. The mechanism of vitamin E inhibition of PGE2 production in macrophages was investigated. The release of (14C)-arachidonic acid from pre-labeled macrophages and the conversion of (14C)-arachidonic acid to PGE2 by the homogenate of the cells were remarkably reduced. These results strongly suggested that the inhibition of PGE2 production by vitamin E results from the inhibition of the activities of both phospholipase A2 and cyclooxygenase.

Animals↗
PubMed1991

The role of cerebral microvessel endothelium in regulation of cerebral blood flow through production of endothelin-1.

We have previously reported the production of endothelin-1 (ET-1) by the cerebral microvessel endothelia and suggested an important role of ET-1 and microvessel endothelia in the regulation of local blood flow within the brain. In the present study, radioimmunoassay of ET-1 revealed that ET-1, produced by cultured cerebral microvessel endothelia grown on a filter, is released mainly to the basal side (corresponding to the basement membrane side), not to the apical side (corresponding to the vascular lumen side). This might indicate that ET-1 constricts arterioles locally at the same place where it is produced by endothelia. The present results also show that cultured cerebral microvessel endothelia produce less ET-1 under low oxygen pressure and that they produce more ET-1 under low carbon dioxide pressure. Taken together, our results may suggest that the negative feedback regulation of cerebral blood flow through oxygen and carbon dioxide pressure is mediated by ET-1 produced locally by cerebral microvessel endothelia.

Capillaries↗
PubMed1991

Effect of carbon dioxide and oxygen on endothelin production by cultured porcine cerebral endothelial cells.

We have previously reported the production of endothelin, a potent vasoconstrictor peptide, by porcine cerebral microvessel endothelia and suggested its important role in the regulation of local blood flow within the brain. In our present study, radioimmunoassay with anti-porcine endothelin antiserum revealed that endothelin, produced by cerebral microvessel endothelia grown on a filter, is released mainly to the basement membrane side, not the vascular lumen side. This finding suggests that endothelin constricts arterioles locally where it is produced by endothelia. We also found that cerebral microvessel endothelia produce less endothelin under low oxygen pressure and more endothelin under low carbon dioxide pressure. Our results suggest that endothelin has a role in the regulation of cerebral blood flow in response to oxygen and carbon dioxide pressure.

Animals↗
PubMed1991

The role of leukotriene B4 in neutrophil infiltration in experimentally-induced inflammation of rat tooth pulp.

Inflammation was induced in rat dental pulp by applying bacterial lipopolysaccharide (LPS). Extirpated tissue samples from inflamed pulps were incubated in vitro in a Krebs buffer containing Ca2+ ionophore A23187, and leukotriene (LT) B4 released into the medium was determined by radio-immunoassay. Production of LTB4 could be detected three to 24 h after the application of LPS and showed a maximum at 12 h. Histologically, marked infiltration of neutrophils, but not other leukocytes, was characteristically observed in the LPS-applied pulps, and the temporal change in neutrophil infiltration was almost parallel, but somewhat more delayed than LTB4 production. When BW755C, a dual inhibitor of cyclo-oxygenase and lipoxygenase, was given to the animals before the application of LPS, both the production of LTB4 and the number of infiltrated neutrophils were significantly decreased, whereas administration of indomethacin had no effect. These results suggest that LTB4 may be involved in neutrophil infiltration in pulpal inflammation. It was also suggested that a major early source of LTB4 in experimental pulpitis was leukocytes, primary neutrophils, because the synthesis of LTB4 in the inflammed pulp was diminished by depletion of circulating leukocytes with cyclophosphamide prior to the application of LPS.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1990

Synthesis and release of acetylcholine by cultured bovine arterial endothelial cells.

Using cultured endothelial cells prepared from bovine carotid artery, and a specific radioimmunoassay for acetylcholine (ACh), the synthesis and release of ACh by vascular endothelial cells were investigated directly. ACh content in the culture medium after 24 h of incubation in the presence of isoflurophate, a nonspecific cholinesterase inhibitor, was about 16 times higher than that in endothelial cells, indicating that ACh synthesized inside the cells was released rapidly. The presence of ACh in the culture medium was further confirmed qualitatively using high-performance liquid chromatography with an electrocapture detection. These results represent the first direct evidence that endothelial cells can synthesize and release ACh, suggesting the possibility that ACh acts not only as a neurotransmitter but also as an autacoid under certain conditions.

Acetylcholine↗
PubMed1990

Preventive effect of zinc against cadmium-induced bone resorption.

The effects of cadmium and zinc on bone resorption were investigated using fetal mouse calvaria organ culture. Cadmium treatment (0.5 microM) stimulated bone resorption in fetal mouse calvaria via prostaglandin E2 production. Concomitant treatment of zinc with cadmium prevented bone resorption by cadmium in a dose-dependent manner of zinc. The zinc treatment also prevented the stimulation of prostaglandin E2 production by cadmium. ID50 of zinc for bone resorption showed high similarity to that for prostaglandin E2 production (1.2 microM and 1.6 microM, respectively). To simplify the system, we used osteoclast-enriched and osteoblast-enriched cell populations obtained from mice calvariae by collagenase digestion method. Prostaglandin E2 was produced in osteoblast-enriched cell culture more than in osteoclast-enriched cell culture. Cadmium stimulated prostaglandin E2 production in osteoblast-enriched cell culture, but not in osteoclast-enriched cell culture. Zinc also prevented the stimulatory effect of cadmium on prostaglandin E2 production in osteoblast-enriched cell culture. Zinc partially, but significantly, inhibited cadmium-accumulation in both calvaria and osteoblast-enriched cell culture. These results strongly suggest that zinc prevents cadmium-induced prostaglandin E2 production and bone resorption through the interaction between the two metals on osteoblasts involved in the inhibition of cadmium-accumulation.

Animals↗
PubMed1990

Cerebral microvessel endothelium is producing endothelin.

Endothelin, a potent vasoconstrictor peptide, was recently isolated from the supernatant of the cultured endothelia of the porcine aorta and is now supposed to be the most likely candidate for the endothelium-derived contractile factor (EDCF), which is responsible for the endothelium-dependent vasoconstriction by various stimuli. In this study, the production of endothelin by the endothelia of porcine cerebral microvessels was revealed by the Northern blot analysis with porcine endothelin cDNA probe and the enzyme-linked immunosorbent assay (ELISA) with anti-porcine endothelin antibody. Our results raise the possibility that the endothelia of cerebral microvessels regulate the local blood flow within the brain through the production of endothelin.

Animals↗
PubMed1990

Prostacyclin does not play any cytoprotective role in endothelial cell injury induced by 15-hydroperoxy-eicosatetraenoic acid, an arachidonate lipoxygenase product.

Among various arachidonic acid metabolites examined, only 15(S)-hydroxperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE), a lipoxygenase product, caused a time- and dose-dependent injury to bovine endothelial cells in culture. There also occurred a significant inhibition of endothelial prostacyclin (PGI2) production due to 15-HPETE. But there were obvious dissociations in time course and dose dependence between 15-HPETE-induced cellular injury and 15-HPETE-induced inhibition of PGI2 synthesis. In addition, the cytotoxicity of 15-HPETE was not aggravated even when the endothelial monolayers were pretreated with several inhibitors of PGI2 synthesis. Also, some stable analogues of PGI2 had no protective effect on the injury. These results suggest that the reduced production of PGI2 caused by 15-HPETE is not directly associated with the onset of cellular injury, and that PGI2 does not play any cytoprotective role in endothelial cell injury induced by at least such lipid peroxides as 15-HPETE.

Animals↗