Cilostazol Inhibits Vascular Smooth Muscle Cell Proliferation and Reactive Oxygen Species Production through Activation of AMP-activated Protein Kinase Induced by Heme Oxygenase-1

Cilostazol is a selective inhibitor of phosphodiesterase 3 that increases intracellular cAMP levels and activates protein kinase A, thereby inhibiting vascular smooth muscle cell (VSMC) proliferation. We investigated whether AMP-activated protein kinase (AMPK) activation induced by heme oxygenase-1 (HO-1) is a mediator of the beneficial effects of cilostazol and whether cilostazol may prevent cell proliferation and reactive oxygen species (ROS) production by activating AMPK in VSMC. In the present study, we investigated VSMC with various concentrations of cilostazol. Treatment with cilostazol increased HO-1 expression and phosphorylation of AMPK in a dose- and time-dependent manner. Cilostazol also significantly decreased platelet-derived growth factor (PDGF)-induced VSMC proliferation and ROS production by activating AMPK induced by HO-1. Pharmacological and genetic inhibition of HO-1 and AMPK blocked the cilostazol-induced inhibition of cell proliferation and ROS production.These data suggest that cilostazol-induced HO-1 expression and AMPK activation might attenuate PDGF-induced VSMC proliferation and ROS production.

Aprotinin Inhibits Vascular Smooth Muscle Cell Inflammation and Proliferation via Induction of HO-1

Aprotinin is used clinically in cardiopulmonary bypass surgery to reduce transfusion requirements and the inflammatory response. The mechanism of action for the anti-inflammatory effects of aprotinin is still unclear. We examined our hypothesis whether inhibitory effects of aprotinin on cytokine-induced inducible nitric oxide synthase (iNOS) expression (IL-1beta plus TNF-alpha), reactive oxygen species (ROS) generation, and vascular smooth muscle cell (VSMC) proliferation were due to HO-1 induction in rat VSMCs. Aprotinin induced HO-1 protein expression in a dose-dependent manner, which was potentiated during inflammatory condition. Aprotinin reduced cytokine mixture (CM)-induced iNOS expression in a dose dependent manner. Furthermore, aprotinin reduced CM-induced ROS generation, cell proliferation, and phosphorylation of JNK but not of P38 and ERK1/2 kinases. Aprotinin effects were reversed by pre-treatment with the HO-1 inhibitor, tin protoporphyrin IX (SnPPIX). HO-1 is therefore closely involved in inflammatory-stimulated VSMC proliferation through the regulation of ROS generation and JNK phosphorylation. Our results suggest a new molecular basis for aprotinin anti-inflammatory properties.

Heme Oxygenase-1 Induced by Aprotinin Inhibits Vascular Smooth Muscle Cell Proliferation Through Cell Cycle Arrest in Hypertensive Rats

Spontaneous hypertensive rats (SHR) are an established model of genetic hypertension. Vascular smooth muscle cells (VSMC) from SHR proliferate faster than those of control rats (Wistar-Kyoto rats; WKY). We tested the hypothesis that induction of heme oxygenase (HO)-1 induced by aprotinin inhibits VSMC proliferation through cell cycle arrest in hypertensive rats. Aprotinin treatment inhibited VSMC proliferation in SHR more than in normotensive rats. These inhibitory effects were associated with cell cycle arrest in the G1 phase. Tin protoporphyrin IX (SnPPIX) reversed the anti-proliferative effect of aprotinin in VSMC from SHR. The level of cyclin D was higher in VSMC of SHR than those of WKY. Aprotinin treatment downregulated the cell cycle regulator, cyclin D, but upregulated the cyclin-dependent kinase inhibitor, p21, in VSMC of SHR. Aprotinin induced HO-1 in VSMC of SHR, but not in those of control rats. Furthermore, aprotinin-induced HO-1 inhibited VSMC proliferation of SHR. Consistently, VSMC proliferation in SHR was significantly inhibited by transfection with the HO-1 gene. These results indicate that induction of HO-1 by aprotinin inhibits VSMC proliferation through cell cycle arrest in hypertensive rats.

Kinetic Changes of COX-2 Expression during Reperfusion Period after Ischemic Preconditioning Play a Role in Protection Against Ischemic Damage in Rat Brain

A brief ischemic insult induces significant protection against subsequent massive ischemic events. The molecular mechanisms known as preconditioning (PC)-induced ischemic tolerance are not completely understood. We investigated whether kinetic changes of cyclooxygenase (COX)-2 during reperfusion time-periods after PC were related to ischemic tolerance. Rats were given PC by occlusion of middle cerebral artery (MCAO) for 10 min and sacrificed after the indicated time-periods of reperfusion (1, 2, 4, 8, 12, 18 or 24 h). In PC-treated rats, focal ischemia was induced by occlusion of MCA for 24 h and brain infarct volume was then studied to determine whether different reperfusion time influenced the damage. We report that the most significant protection against focal ischemia was obtained in rats with 8 h reperfusion after PC. Administration of indomethacin (10 mg/kg, oral) or rofecoxib (5 mg/kg, oral) 48 h prior to PC counteracted the effect of PC. Immunohistochemical analysis showed that COX-2 and HO-1 protein were induced in PC-treated rat brain, which was significantly inhibited by rofecoxib. Taken together, we concluded that the kinetic changes of COX-2 expression during the reperfusion period after PC might be partly responsible for ischemic tolerance.

Evaluation of Curriculums of Medical Schools for Fostering Various Basic Qualities of Medical Professionalism / 한국의학교육

PURPOSE: Today, the social requirement of medicine emphasizes the importance of medical professionalism. This forces medical educators to introduce new contents and methods into the curriculum. This study aims to offer ideas for developing the curriculum through clarifying priorities on the basic qualities of medical professionalism and evaluating the current curriculums in medical schools in South Korea. METHODS: In April 2005, 46 respondents majoring in basic medical sciences, clinical medicine, and medical humanities/social sciences completed a structured questionnaire. The questionnaire consisted of 3 categories related to: 1) the basic qualities of medical professionalism/general education courses, 2) the process of developing the qualities of humanities and social sciences in medical education, and 3) the appropriate allocation of credits for each subject to premedical and medical courses. The analysis consisted of frequency, chi-square, and multiple responses using Korean Ed, SPSS 14.0 for Windows. RESULTS: The most important basic quality is basic medical knowledge. The credits for the general education are sufficient but it's contribution is lacking (44.44%). The most lacking element in the general education courses is socio-cultural comprehension (45.65%). The knowledge of humanities and social sciences is very important in developing the basic qualities (56.52%). The important learning experiences related to these is the introspection into human beings (32.16%). Credits for medical humanities classes in premedical and medical course are noticeably insufficient (45.65, 54.35%, respectively). The appropriate program of informal curriculum for fostering the qualities is meeting with various medical specialists (44.44%, 47.83%, respectively). There is almost no difference among the major groups under (p<.05.) CONCLUSION: To assist medical students to be equipped with the basic qualities of medical professionalism, the realm of medical humanities should be made mandatory; and the general education courses need to be reformed, especially in the premedical curriculum. In particular, continuous cooperation between faculties in medicine, liberal arts, and/or social sciences need to exist with the conglomeration of these into fewer medical humanities majors in Korea.

Effects of Antioxidants on the Gamma-Radiation Damage of the Cultured Vascular Smooth Mucle Cells of Rat Aorta

To study the protective effects of antioxidants on the radiation damages of the cells, vascular smooth muscle cells (VSMC) from thoracic aorta of Sprague-Dawley rats were cultured and irradiated with gamma-ray. Cell viability was measured by direct cell counting and MTT assay, and flow cytometry was performed to measure fractional distributions of the cells. Gamma-ray irradiation inhibited cell proliferations accompanied with decreased G1 phase and increased S- and G2/M phases, and the maximum effects were observed at 1500 or 2000 cGy. Submaximal concentrations of antioxidants, such as allopurinol, vitamin C, N-acetylcycteine (NAC), lipoic acid, dihydrolipoic acid and rebamipide tended to increase the cell viability suppressed by low dose of radiation (500 cGy), and enalapril and vitamin E increased it significantly. Allopurinol, vitamin E, NAC, lipoic acid, captopril and enalapril significantly increased G1 phase. Allopurinol and vitamin E tended to increase c-Myc expression, detected by Western blot, that was reduced by the radiation, and enalapril increased it significantly. The cell viability and c-Myc expression were highly correlated (r=0.97) with each other. These results suggest that antioxidants, especially enalapril and vitamin E, recover the viability of VSMC from gamma-radiation injury, through a mechanism which includes increase of c-Myc protein expression.

Nitric Oxide Donor, NOR-3, Increased Expression of Cyclooxygenase-2, but not of Cyclooxygenase-1 in Cultured VSMC

NO and cyclooxygenase-2 (COX-2) are contributes to vascular inflammation induced by various stimulation. The mechanism, which explains a linkage between NO and COX-2, could be of importance in promoting pathophysiological conditions of vessel. We investigated the effects of NO donors on the COX-1 and COX-2 mRNA/protein expression, as well as the nitrite production in culture medium of vascular smooth muscle cell (VSMC). VSMC was primarily cultured from thoracic aorta of rat. In this experiments, COX-1 and COX-2 mRNA/protein expressions were analysed and nitrite productions were investigated using Griess reagent. VSMC did not express COX-2 protein in basal condition (Non-lipopolysaccharide (LPS) stimulated). In LPS-stimulated experiments, after 3 hours of NO donor pretreatment, LPS 10 microgram/ml was treated for 24 hours. COX-1 protein expressions were unchanged by SNP and NOR-3. NOR-3 significantly increased COX-2 mRNA/protein expression under LPS stimulation. In contrast, SNP did not increase COX-2 mRNA/protein expression under LPS stimulation. Nitrite production was higher in NOR-3 treatment than SNP treatment under LPS stimulation. These results suggest that the expression of COX-2 in VSMC is regulated by NOR-3, COX-2 expressions were depending on the types of NO donor and LPS stimulation in VSMC.

The Operating Status of Medical Education Management Units in Korea / 한국의학교육

PURPOSE: The purpose of this study was to estimate the operating status of existing medical education management units in medical colleges and to define the roles of these units to provide basic information to medical schools contemplating to establish similar management units. METHODS: A structured questionnaire survey was conducted via mail. The survey 41 medical colleges across the nation and was done during September 2003 and March 2005. The assessment instrument included six items assessing the organizational structure, composition, major activities, self-satisfaction with performance, administration and financial aspects and the need for further development in the medical education unit for medical colleges with a medical education management unit. There were only two items assessing demand for establishment of a medical education management unit, prerequisite conditions for establishment, the expected role of such a system for medical colleges without a medical education management unit. RESULTS: Of 41 medical colleges, 18 had a medical education management unit as of September 2003 and 32 as of March 2005. The major activities of these 18 management units included curriculum development(26.7%), faculty development(26.7%), support for PBL(16.0%) and OSCE(12.0%). Recently, these units have become involved in enhancing clinical clerkship as well as improving teaching skills. To have a medical education-related unit run smoothly, at least two tenured faculty members majoring in education and medical education were needed. And a compensation systems was required for those professors working in the unit as a second post but without pay. CONCLUSION: This study underscored the importance of professional faculty members, and administrative and financial supports in having a medical education management unit meet its objectives. The role of the dean of medical college seems crucial in deciding how the unit is operated.

Effect of Progesterone on COX-2 Expression and Proliferation of Prostate Stromal Cell / 영남의대학술지

BACKGROUND: Benign prostatic hyperplasia (BPH) is the most common benign tumor in older men; the etiology of this disease remains poorly understood. Testosterone and dihydrotestosterone (DHT) both act as androgen via a single androgen receptor. Testosterone is converted to DHT by 5alpha-reductase in prostatic stromal cells. Progesterone has been reported to inhibit DHT conversion; howevwe, its effect on prostatic stromal cells remains to be elucidated. MATERILAS AND METHODS: In this experiment, we investigated the effect of progesterone on androgen receptor expression induced by DHT. We also tested the effect of progesterone on cyclooxygenase-2 (COX-2) expression, as well as prostate stromal cell proliferation using the cell count kit-8. RESULTS: Progesterone did not cause an increase of prostate stromal cell proliferation. The mRNA expression of the androgen receptor and COX-2 were not changed by progesterone; the expressions of androgen receptor and COX-2 proteins were decreased by progesterone in prostate stromal cells. CONCLUSION: These results suggest that in prostate stromal cells, progesterone decreases androgen receptor protein expression, which results in decrement of COX-2 protein expression. This effect might be mediated by post-transcriptional regulation.

Effects of Cyclooxygenase Inhibitors on Vascular Reactivity and Alterations of Cyclooxygenase Expression / 영남의대학술지

BACKGROUND: There is controversy regarding whether COX-2 specific inhibitors are associated with elevation of blood pressure. We compared the effects of aspirin, indomethacin, and celecoxib for vascular reactivity induced by phenylephrine. We also tested the effects of indomethacin and NO donor on COX-1 and COX-2 protein expression, as well as nitrite production in culture medium of vascular smooth muscle cells. MATERILAS AND METHODS: In this experiment, we used the isometric tension study for vascular reactivity. After 45 minutes of pretreatment with aspirin, indomethacin, celecoxib, and phenylephrine induced contractions were tested. COX-1 and COX-2 protein expressions were analyzed by Western blot and nitrite production by the Griess reaction. RESULTS: Although celecoxib pretreatment caused enhanced arterial contraction, aspirin pretreatment induced more potent arterial contraction than celecoxib in the isometric tension study of rabbit femoral artery. COX-1 protein expression was unchanged by indomethacin, SNP and NOR-3; COX-2 protein expression was increased by the addition of indomethacin, SNP, and NOR-3. Especially, NOR-3, a NO donor, significantly increased COX-2 protein expression with unstimulated conditions as well as LPS stimulation. Induction of nitrite production was higher with NOR-3 treatment than SNP treatment with LPS stimulation. CONCLUSION: These results suggest that aspirin caused more potent vascular contraction than celecoxib and indomethacin. COX-2 expression in VSMC depended on the types of NO donor and LPS stimulation.