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Biomedical subjects

K J Yoo

Publications and source records attributed to K J Yoo.

10 recordsLinked to original sources
PubMed2000

Heart cell transplantation improves heart function in dilated cardiomyopathic hamsters.

BACKGROUND: Little is known about the effect of heart cell transplantation into the dilated cardiomyopathic myocardium. This study was designed to evaluate the effect of heart cell transplantation into dilated cardiomyopathic hamsters. METHODS AND RESULTS: Ventricular heart cells were isolated from 4-week-old BIO 53. 58 hamsters and cultured for 2 weeks before transplantation. The cells were labeled with bromodeoxyuridine (BrdU) before transplantation for identification. Adult hamsters (17 weeks old) were used as recipients. Heart cells (4 x 10(6) cells) or culture medium was transplanted into the left ventricular free wall (transplantation and control groups, respectively, n=12 each). Sham-operated hamsters (n=12) underwent the surgery but not the transplantation. Cyclosporine A was administered subcutaneously to all hamsters daily after the operation. Four weeks after the transplantation, heart function was evaluated with the use of a Langendorff preparation. Histology showed severe focal myocardial necrosis in all groups. BrdU-stained tissue was found at the cell transplantation sites. The transplanted hearts had greater (P:<0. 001) developed pressures at all balloon volumes and improved dP/dt (transplantation 915+/-253 versus control 453+/-120 and sham 530+/-187 mm Hg/s, P:<0.001, balloon volume of 15 microL). No differences in ventricular function were found between control and sham-operated hamsters. CONCLUSIONS: The transplanted ventricular heart cells formed cardiac-like tissue in cardiomyopathic myocardium and improved its contractile function.

Animals↗
PubMed2000

Caspase 3-mediated cleavage of p21WAF1/CIP1 associated with the cyclin A-cyclin-dependent kinase 2 complex is a prerequisite for apoptosis in SK-HEP-1 cells.

Apoptosis of SK-HEP-1 human hepatoma cells induced by treatment with ginsenoside Rh2 (G-Rh2) is associated with rapid and selective activation of cyclin A-associated cyclin-dependent kinase 2 (Cdk2). Here, we show that in apoptotic cells, the Cdk inhibitory protein p21(WAF1/CIP1), which is associated with the cyclin A-Cdk2 complex, undergoes selective proteolytic cleavage. In contrast, another Cdk inhibitory protein, p27(KIP1), which is associated with cyclin A-Cdk2 and cyclin E-Cdk2 complexes, remained unaltered during apoptosis. Ectopic overexpression of p21(WAF1/CIP1) suppressed apoptosis as well as cyclin A-Cdk2 activity induced by treatment of SK-HEP-1 cells with G-Rh2. The suppressive effects of p21(WAF1/CIP1) were much higher in the cells transfected with p21D112N, an expression vector that encodes a p21(WAF1/CIP1) mutant resistant to caspase 3 cleavage. Overexpression of cyclin A in SK-HEP-1 cells dramatically up-regulated cyclin A-Cdk2 activity and accordingly enhances apoptosis induced by treatment with G-Rh2. These up-regulating effects were blocked by coexpression of a dominant negative allele of cdk2. Furthermore, olomoucine, a specific inhibitor of Cdks, also blocked G-Rh2-induced apoptosis. These data suggest that the induction of apoptosis in human hepatoma cells treated with G-Rh2 occurs by a mechanism that involves the activation of cyclin A-Cdk2 by caspase 3-mediated cleavage of p21(WAF1/CIP1).

Apoptosis↗
PubMed2000

Autologous smooth muscle cell transplantation improved heart function in dilated cardiomyopathy.

BACKGROUND: Transplantation of myocytes into scarred myocardium has been shown to inhibit ventricular remodeling and maintain myocardial contractility. However, the effect of cell transplantation on hearts with global rather than regional dysfunction is unknown. Therefore, we evaluated the effect of transplantation of autologous smooth muscle cells on the morphometry and function of dilated cardiomyopathic hearts. METHODS: Smooth muscle cells were isolated from the ductus deferens of 13-week-old BIO 53.58 hamsters with dilated cardiomyopathy, and cultured for 4 weeks before transplantation. Smooth muscle cells (4 x 10(6) cells) or culture medium were injected into 17-week-old animals in the transplantation and control groups (n = 12 each), respectively. Prelabeling of the smooth muscle cells with 5-bromo-2'-deoxyuridine was performed before transplantation in a group of transplanted hamsters. Another group (sham, n = 12) underwent the operation but did not receive an injection either of smooth muscle cells or of culture medium. Four weeks after transplantation, heart function was evaluated in a Langendorff preparation. RESULTS: Musclelike tissue, labeled with 5-bromo-2'-deoxyuridine, was found at the site of transplantation in the cell-transplanted animals. The cell-transplanted hearts were smaller (p < 0.001), and had greater developed pressures and maximum rate of increase of left ventricular pressure (both p < 0.001) than control and sham hearts. Control hamsters injected with culture medium did not differ from sham-operated animals. CONCLUSIONS: Transplantation of autologous smooth muscle cells prevented cardiac dilatation and improved ventricular function in hamsters with dilated cardiomyopathy.

Animals↗
PubMed1999

Noninvasive evaluation of coronary artery bypass graft patency using three-dimensional angiography obtained with contrast-enhanced electron beam CT.

OBJECTIVE: The purpose of this study was to determine the accuracy of three-dimensional coronary angiography obtained with electron beam CT in the assessment of the patency of coronary artery bypass grafts. SUBJECTS AND METHODS: Twenty-five patients who had undergone coronary artery bypass graft surgery were included. All patients underwent electron beam CT and conventional coronary angiography for the evaluation of the status of their bypass grafts. Three-dimensional reconstructions of the heart and bypass grafts were compared with selective angiographic images of the bypass grafts. RESULTS: Fifty-seven saphenous vein grafts and 22 left internal mammary artery grafts were evaluated for occlusion or patency. Sensitivity and specificity of electron beam CT in revealing left internal mammary artery patency were 80% and 82.4%, respectively. Sensitivity and specificity of electron beam CT in revealing saphenous vein graft patency were 91.7% and 91.1%, respectively. Sensitivity and specificity of electron beam CT for evaluating saphenous vein grafts according to coronary area were as follows: saphenous vein grafts to left anterior descending artery, 100% and 100%, respectively; to diagonal branch, 100% and 100%; to left circumflex artery, 100% and 88.9%; and to right coronary artery, 75% and 85.7%. CONCLUSION: Three-dimensional coronary angiography obtained with electron beam CT is a promising, useful, and relatively accurate diagnostic imaging technique for the evaluation of graft patency in patients who have undergone coronary artery bypass graft surgery.

Coronary Angiography↗
PubMed1998

Expression of vimentin and cytokeratin in eutopic and ectopic endometrium of women with adenomyosis and ovarian endometrioma.

PROBLEM: To determine the expression of vimentin and cytokeratin in eutopic and ectopic endometrium of women with both adenomyosis and ovarian endometrioma and to evaluate their cyclic changes during the menstrual cycle. METHOD OF STUDY: Twenty patients requiring hysterectomy with salpingo-oophorectomy were studied by immunohistochemistry according to their menstrual cycles. RESULTS: Cyclic expression of vimentin was noted in eutopic endometrium and adenomyosis, but not in endometrioma. Cytokeratin expression did not change during the menstrual cycles. The mean intensities of epithelial vimentin were significantly different from each other, being the lowest in endometrioma, intermediate in adenomyosis, and the highest in eutopic endometrium. There was no significant difference in intensities of cytokeratin between adenomyosis and endometrioma, but these intensities were significantly lower than that of eutopic endometrium. CONCLUSIONS: Lower intensities of cytokeratin in adenomyosis and endometrioma than in eutopic endometrium suggest that the ectopic endometria may have a lower degree of differentiation regardless of the site. The lower intensity of epithelial vimentin in endometrioma than in adenomyosis during the proliferative phase may reflect decreased functional activity, probably because of a pressure effect on the lining epithelium within the endometrioma.

Endometrial Neoplasms↗
PubMed1995

Cyproheptadine augmentation of haloperidol in chronic schizophrenic patients: a double-blind placebo-controlled study.

A 6 week double-blind placebo-controlled trial of cyproheptadine augmentation of ongoing haloperidol treatment was conducted in 40 chronic schizophrenic in-patients. Cyproheptadine augmentation, compared to administration of haloperidol with placebo, did not produce a statistically significant improvement in psychotic symptoms. Cyproheptadine augmentation caused significant reduction in the extrapyramidal symptoms, which supports the atypical profile of antipsychotics. As to the neuroendocrinological effect, cyproheptadine augmentation did not reduce the plasma prolactin level but did induce a decrease in the plasma cortisol level. Although long-term follow-up studies are needed to confirm the results, this study suggests that cyproheptadine augmentation may be effective in treating chronic schizophrenic patients who are intolerant of extrapyramidal side effects of conventional antipsychotics.

Adult↗
PubMed1994

Mechanism of decrease in heart rate by peripheral dopaminergic D2-receptors.

We performed this study in order to verify the heart rate decrease caused by the D2-receptor on cardiac sympathetic nerve endings and its relation to the concentration of norepinephrine in synaptic clefts. Sprague-Dawley rats were pithed and the heart rate was increased either by electrical stimulation of the cardiac accelerator nerve or by intravenous infusion of norepinephrine, tyramine, or isoproterenol. Increased heart rate by electrical stimulation of cardiac accelerator nerve was dose-dependently lowered by lisuride and its effect was blocked by pretreatment with sulpiride but not with yohimbine and SCH 23390. Also, the heart rate was decreased in a dose-dependent manner by clonidine and this effect was blocked by pretreatment with yohimbine, but not with sulpiride. For increased heart rate by infusion of norepinephrine, tyramine, or isoproterenol, the heart rate lowering effect of lisuride was more marked in the norepinephrine-and tyramine-infusion groups, in which the intrasynaptic concentration of norepinephrine was elevated, compared to the isoproterenol-infusion group, in which intrasynaptic concentration of norepinephrine was not elevated. In conclusion, there is a D2-receptor on the cardiac sympathetic nerve endings which decreases the heart rate and is different from the presynaptic alpha 2-receptor. Also, the heart rate lowering effect via stimulation of the D2-receptor by lisuride was more marked with increased concentration of norepinephrine in the synaptic cleft.

Animals↗
PubMed1994

Impairement of endothelium-dependent relaxation in chronic two-kidney, one clip hypertensive rats.

OBJECTIVES: Hypertension is commonly associated with an endothelial dysfunction that may contribute to the rise in blood pressure. Little information has been available so far on the role of endothelium-derived nitric oxide(EDNO) in renin-dependent, 2-kidney, 1 clip(2KIC) hypertension. The present study was aimed to determine a role for EDNO in the development and maintenance of 2KIC hypertension. METHODS: The effects of blocking synthesis or supplementation with precursor of EDNO on the development of hypertension were determined in 2KIC rats. Vascular responses to acetylcholine, nitroprusside, atrial natriuretic peptide and nifedipine were examined in 7- and 12-week hypertensive 2KIC rats. RESULTS: NG-nitro-L-arginine-methyl ester caused a sustained increase of blood pressure in normal rats, while it was only partially associated with a more pronounced increase of blood pressure in the developmental phase of hypertension in 2KIC rats. In 7-week and 12-week hypertensive rats, phenylephrine-induced contraction of the isolated thoracic aortic rings was more sensitive compared with control. Their acetylcholine-induced relaxation was attenuated while the responses to nitroprusside or atrial natriuretic peptide were unaltered. Although their blood pressure did not differ between 7-week and 12-week hypertensive groups, the attenuation in the acetylcholine-induced relaxation was more prominent in the latter with a longer duration of hypertension. Indomethacin did not affect the attenuated relaxation to acetylcholine. The relaxation response to nifedipine was more pronounced in 2KIC rats. CONCLUSION: These results indicate that ENDO has little influence of the 2KIC hypertension, at least during its developmental phase, which is associated with an activated reninangiotensin system. The chronic stage of 2KIC hypertension, however, is associated with an endothelial dysfunction which may contribute to the enhanced vasoconstriction and sustained high blood pressure.

Acetylcholine↗
PubMed1993

Regional differences in the levels of biogenic amines and their metabolites in rat brain after tricyclic antidepressant treatments.

Changes in the levels of biogenic amines in different brain regions and the cerebrospinal fluid in rats were measured after acute or chronic treatment with tricyclic antidepressants. After single or 3 weeks' treatment with imipramine or desipramine, blocks of tissues were obtained from seven regions of the brain (frontal cortex, corpus striatum, hippocampus, thalamus, hypothalamus, substantia nigra and cerebellum) immediately after collection of the cerebrospinal fluid (CSF) from the cisterna magna. The concentrations of biogenic amines and their metabolites (norepinephrine, epinephrine, dopamine, 5-hydroxytryptamine (5-HT), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA)) in brain tissues and the CSF were measured using the high performance liquid chromatography-electrochemical detection system (HPLC-ECD). Treatment with desipramine or imipramine caused major alterations in the concentrations of central norepinephrine or 5-HT and its metabolite, respectively. Brain regional responses were variable according to the kind of tricyclic antidepressants and the duration of treatment. It is noteworthy that chronic treatment with both desipramine and imipramine caused altered hippocampal concentrations of norepinephrine and/or 5-HT and its metabolites. Striatal DOPAC concentrations were also changed after acute or chronic treatment with both drugs. These results suggest that tricyclic antidepressants altered neurotransmission according to the brain region, and the hippocampal norepinephrine and 5-HT and/or the striatal dopamine may have a significant role for the expression of antidepressant action of tricyclic antidepressants.

Animals↗