9 results on '"Suchen L. Hong"'
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2. Characterization of cytosolic phospholipases C from porcine aortic endothelial cells
- Author
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Yigong Fu, Suchen L. Hong, and Jin-xuan Cheng
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Swine ,Immunoblotting ,Biology ,Isozyme ,Catalysis ,chemistry.chemical_compound ,Cytosol ,Extracellular ,Animals ,Phosphatidylinositol ,Aorta ,Cells, Cultured ,Phospholipase C ,Brain ,Hematology ,Hydrogen-Ion Concentration ,Chromatography, Agarose ,Isoenzymes ,Endothelial stem cell ,Biochemistry ,chemistry ,Cell culture ,Type C Phospholipases ,Second messenger system ,Calcium ,Cattle ,Electrophoresis, Polyacrylamide Gel ,Endothelium, Vascular ,Deoxycholic Acid - Abstract
Phospholipases C (PLCs) are ubiquitous enzymes which play key roles in the response of cells to extracellular agonists. Endothelial cells are involved in myriad normal and pathophysiologic functions. Although it is known that agonists activate PLCs in endothelial cells, second messengers form, and cellular responses ensue, more knowledge is needed about the specific types of PLCs in these cells. To this end, cytosolic PLCs from porcine aortic endothelial cells were partially purified by ammonium sulfate fractionation and column chromatography on DEAE-Sepharose CL-6B and heparin-agarose. Three PLC isozymes immunologically similar to bovine brain PLC-beta, PLC-gamma, and PLC-delta were identified. The relative levels of PLC activities in the cytosol were: PLC-beta, 50%; PLC-gamma, 44%; PLC-delta, 6%. The level of PLC-beta activity in porcine endothelial cells appeared higher than the levels reported for several established cell lines, suggesting that this enzyme may play a specific role in endothelial cell function. Elution profiles of PLC activity with phosphatidylinositol 4,5-bisphosphate (Ptdlns(4,5)P2) as substrate were similar to those with phosphatidylinositol (Ptdlns) as substrate, indicating that cytosolic PLCs hydrolyze both Ptdlns and Ptdlns(4,5)P2 and no Ptdlns(4,5)P2-specific PLC was present in the cytosol. The catalytic properties of the partially purified PLC isozymes from porcine endothelial cells were similar to their counterparts from bovine brain. These include the dependence of hydrolysis of Ptdlns on Ca2+, the optimal Ca2+ concentrations for the hydrolysis of Ptdlns and Ptdlns(4,5)P2, the pH optima, and the stimulatory effects of deoxycholate. more...
- Published
- 1994
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3. Glycoconjugate mediated endothelial cell adhesion to Dacron polyester film*
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C. Keith Ozaki, Matthew D. Phaneuf, Frank W. LoGerfo, Suchen L. Hong, and William C. Quist
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chemistry.chemical_classification ,biology ,Glycoconjugate ,business.industry ,Cell ,Lectin ,Biomaterial ,Adhesion ,Ligand (biochemistry) ,Molecular biology ,Endothelial stem cell ,chemistry.chemical_compound ,medicine.anatomical_structure ,chemistry ,Immunology ,medicine ,Polyethylene terephthalate ,biology.protein ,Surgery ,Cardiology and Cardiovascular Medicine ,business - Abstract
Purpose: The purpose of this study was to explore new strategies for enhancing specific cell type attachment to biomaterials using immobilized lectins for cell surface glycoconjugates. The lectin Ulex europaeus I (UEA I) has a high affinity for human vascular endothelial cell surface glycoconjugates. Methods: UEA I was covalently bound to polyethylene terephthalate (Dacron) with the cross-linking agent 1-ethyl-3-(dimethylaminopropyl) carbodiimide hydrochloride to achieve oligosaccharide-mediated endothelial cell attachment to this otherwise nonadherent surface. Results: Experiments with radiolabeled UEA I demonstrated covalent linkage of as much as 1.35 μg/cm 2 . The lectin binding site is available after the reaction, as demonstrated in experiments a neoglycoprotein. Adhesion studies reveal a 100-fold increase in endothelial cell attachment for the UEA I/polyethylene terephthalate surface (99.7 ± 29.6 cells/high-power field) when compared with untreated (0.7 ± 0.5), crosslinking agent (0.4 ± 0.3), and denatured UEA I (1.2 ± 1.1) control groups. Five vascular endothelial cell lines adhered to the UEA I/polyethylene terephthalate surface, whereas monocytes, smooth muscle cells, and fibroblasts did not. Conclusion: These results imply new strategies for endothelialization of prosthetic grafts and promotion of selective cell adherence to biomaterials, with emphasis on carbohydrate interactions. Moreover, this experimental system offers a model for exploring the biologic significance of the endothelial cell-UEA I ligand. (J VASC SURG 1993;18:486-94.) more...
- Published
- 1993
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4. Arachidonic acid level in cellular lipids determines the amount of prostaglandins synthesized during cell growth in tissue culture
- Author
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Suchen L. Hong, Daniel Deykin, and George Patton
- Subjects
medicine.medical_specialty ,Time Factors ,medicine.medical_treatment ,Stimulation ,Arachidonic Acids ,Biology ,Bradykinin ,Models, Biological ,Biochemistry ,Cell Line ,Mice ,chemistry.chemical_compound ,Tissue culture ,Endocrinology ,Culture Techniques ,Internal medicine ,medicine ,Animals ,Growth medium ,Cell growth ,Prostaglandins E ,Prostaglandins F ,Thrombin ,Fibroblasts ,Lipid Metabolism ,Culture Media ,Cell Transformation, Neoplastic ,chemistry ,Prostaglandin-Endoperoxide Synthases ,Cell culture ,Methylcholanthrene ,Arachidonic acid ,Prostaglandin E - Abstract
Methylcholanthrene transformed mouse fibroblast cells can be induced to synthesize prostaglandins by a short term incubation with various vasoactive agents including serum, bradykinin and thrombin or in response to mechanical detachment from the culture dish. The ability of the cells to synthesize prostaglandins upon stimulation changes during growth of the culture on the dish; the response is maximal on the first day after inoculation and decreased sharply thereafter. Feeding of the cells with fresh growth medium enhances prostaglandin production induced by all stimuli. The difference in the cell response during growth is probably not due to change of prostaglandin synthetase activity since the specific enzyme activities assayed with microsomal preparations of cells harvested from the first and third day culture are similar. However, analysis of the cellular content of arachidonic acid after saponification of the total lipid extract of cells harvested at different days of growth reveals that the level of arachidonic acid per cell during growth is parallel to the response to stimuli. It is maximal on the first day and decreases sharply on the second day and stays low on the third day. Our study suggests that the level of arachidonic acid in the cell governs the extent of prostaglandin synthesis upon stimulation. more...
- Published
- 1979
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5. Effect of bradykinin and thrombin on prostacyclin synthesis in endothelial cells from calf and pig aorta and human umbilical cord vein
- Author
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Suchen L. Hong
- Subjects
Umbilical Veins ,medicine.medical_specialty ,Swine ,Metabolite ,Bradykinin ,Stimulation ,Prostacyclin ,Arachidonic Acids ,chemistry.chemical_compound ,Thrombin ,Internal medicine ,medicine ,Animals ,Humans ,Aorta, Abdominal ,Endothelium ,Calcimycin ,business.industry ,Radioimmunoassay ,Hematology ,Trypsin ,Epoprostenol ,Endocrinology ,Biochemistry ,chemistry ,Prostaglandins ,Cattle ,Arachidonic acid ,Rabbits ,business ,medicine.drug - Abstract
We have discovered that bradykinin is effective in causing the synthesis of prostacyclin in endothelial cells cultured from calf and pig aorta and human umbilical cord vein. Maximal stimulation is attained at 10 ng bradykinin per ml with a 10 fold increase of PGI 2 as assayed by radioimmunoassay for 6-k-PGF 1α . Ionophore A23187, trypsin, and the precursor arachidonic acid are also stimulatory. We have confirmed the study of Weksler et al ( J. Clin. Invest., 62 , 923, 1978) and Czervionke et al ( Thrombosis Research, 14 , 781, 1979) that thrombin is effective in stimulating PGI 2 synthesis in endothelial cells from human umbilical cord vein. However, we found that cells from calf or pig aorta are not stimulated as well by thrombin. Thus, there appears to be a difference in the response to thrombin between these cells. When calf cells were grown in the presence of [ 3 H]arachidonic acid, the radioactivity is incorporated mainly into the phospholipids. Bradykinin, ionophore A23187, and trypsin stimulated the release of radioactive materials into medium from [ 3 H]arachidonic acid labeled calf cells. Arachidonic acid is the major radioactive substance released and PGI 2 is the major known arachidonic acid metabolite formed. more...
- Published
- 1980
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6. Favorable balance of prostacyclin and thromboxane A2 improves early patency of human in situ vein grafts
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Daniel Deykin, Melissa E. McCabe, Harry L. Bush, Donald C. Nabseth, John N. Graber, Suchen L. Hong, and Joseph A. Jakubowski
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In situ ,medicine.medical_specialty ,Endothelium ,Thromboxane ,business.industry ,Vasodilation ,Prostacyclin ,Surgery ,Endothelial stem cell ,Thromboxane A2 ,chemistry.chemical_compound ,medicine.anatomical_structure ,chemistry ,Internal medicine ,cardiovascular system ,medicine ,Cardiology ,Cardiology and Cardiovascular Medicine ,Vein ,business ,medicine.drug - Abstract
Graft thrombosis soon after reconstruction remains a major obstacle to the use of reversed vein grafts in infrapopliteal reconstruction. Our clinical experience with in situ vein grafts corroborates Leather's results by demonstrating an overall graft patency of 95% below the knee at 1 year and 94% in the infrapopliteal group. It has been postulated that this improved early patency rate of in situ vein grafts is the result of more optimal preservation of the endothelium of the vein graft. To investigate this hypothesis, human saphenous veins were handled by an in situ and a reversed technique. The intact vein segments were then tested for luminal production of prostacyclin and thromboxane A 2 and fixed for scanning electron microscopic analysis of the surface morphology. This study demonstrated that endothelial cell prostacyclin release is enhanced in human in situ vein segments but not in reversed vein segments. In addition, luminal production of thromboxane A 2 is significantly greater in the reversed than in the in situ vein segments. These findings are associated with marked endothelial structural damage in the reversed veins and minimal endothelial disruption in the situ veins. Therefore the ratio of the antiaggregatory vasodilator prostacyclin to the proaggregatory vasoconstrictor thromboxane A 2 is significantly more favorable for the in situ vein segment than for the reversed vein segment. The observed excellent early patency of the situ vein grafts in our poor-risk patient population may in part be the result of this favorable balance of prostacyclin and thromboxane A 2 and the more optimally preserved endothelial morphology. (J VASC SURG 1984;1:149-59.) more...
- Published
- 1984
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7. The Release of Arachidonic Acid from Cellular Lipids (Part 2 of 2)
- Author
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Suchen L. Hong
- Subjects
chemistry.chemical_compound ,Biochemistry ,Chemistry ,Arachidonic acid - Published
- 1988
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8. Inhibition of prostacyclin synthesis in endothelial cells by methylisobutylxanthine is not mediated through elevated cAMP level
- Author
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Suchen L. Hong
- Subjects
medicine.medical_specialty ,Umbilical Veins ,Swine ,Biophysics ,6-Ketoprostaglandin F1 alpha ,Arachidonic Acids ,Phospholipase ,Biochemistry ,Muscle, Smooth, Vascular ,chemistry.chemical_compound ,Endocrinology ,Phospholipase A2 ,Theophylline ,Pregnancy ,Internal medicine ,1-Methyl-3-isobutylxanthine ,medicine ,Cyclic AMP ,Animals ,Humans ,Endothelium ,Aorta ,Forskolin ,Arachidonic Acid ,biology ,Phospholipase C ,Phosphodiesterase ,Phosphatidic acid ,Epoprostenol ,Endothelial stem cell ,Kinetics ,chemistry ,Bucladesine ,biology.protein ,Arachidonic acid ,Female - Abstract
Methylisobutylxanthine (MIX) raised cAMP levels and inhibited prostacyclin synthesis and arachidonic acid release in endothelial cells from both pig aorta and human umbilical vein. These effects were reversible and dose dependent on MIX concentrations. Dibutyryl cAMP (3 mM) alone did not inhibit prostacyclin synthesis or arachidonic acid release. When added with MIX, dibutyryl cAMP did not enhance the inhibition elicited by MIX. MIX inhibited the formation of lysophospholipids, 1,2-diacylglycerol and phosphatidic acid in bradykinin-stimulated pig endothelial cells, suggesting that the inhibition of prostacyclin synthesis resulted from an apparent inhibition of both phospholipase A2 and phospholipase C. Other phosphodiesterase inhibitors, theophylline and mopidamole, also raised cAMP levels and inhibited arachidonic acid release. However, there was no correlation between cAMP levels and these inhibitions. Forskolin, an adenylate cyclase activator, elevated intracellular cAMP levels with no apparent inhibition on prostacyclin synthesis. We conclude that the inhibitory effect of MIX on phospholipase A2 and phospholipase C is probably through mechanisms other than the elevation of the cAMP level. more...
- Published
- 1983
9. The Release of Arachidonic Acid from Cellular Lipids (Part 1 of 2)
- Author
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Suchen L. Hong
- Subjects
chemistry.chemical_compound ,chemistry ,Biochemistry ,Arachidonic acid ,CYP2C8 - Published
- 1988
- Full Text
- View/download PDF
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