Background-Diabetes mellitus causes multiple cardiovascular complications. High glucose can induce reactive oxygen species and apoptosis in endothelial cells. Little is known about the molecular mechanisms in high glucose-induced endothelial cell apoptosis. Methods and Results-We elucidated the signaling pathway of high glucose-induced apoptosis in human umbilical vein endothelial cells (HUVECs). HUVECs were treated with media containing 5.5, 19, or 33 mmol/L of glucose in the presence or absence of an antioxidant, ascorbic acid. The level of intracellular H 2 O 2 was measured by flow cytometry. For detection of apoptosis, the cell death detection ELISA assay and the morphological Hoechst staining were used. High glucose was capable of inducing the activity of c-Jun NH 2 -terminal kinase (JNK) but not extracellular signal-regulated kinase 1/2 or p38 mitogen-activated protein kinase during the treatment periods, as evidenced by immunocomplex kinase assay. Moreover, we found that the interleukin 1␤-converting enzyme (ICE)/CED-3 family protease (caspase-3) became activated in high glucose-induced apoptosis. Caspase-3/CPP32-specific inhibitor, Ac-DEVD-CHO, could inhibit high glucose-induced apoptosis. Furthermore, we found that JNK1 specific antisense oligonucleotide could suppress caspase-3 activity but not affect H 2 O 2 generation and could block apoptosis induced by high glucose. Also, H 2 O 2 generation, JNK activity, caspase-3 activity, and the subsequent apoptosis induced by high glucose could be suppressed by ascorbic acid. Conclusions-The present study indicates that reactive oxygen species induced by high glucose may be involved in JNK activation, which in turn triggers the caspase-3 that facilitates the apoptosis in HUVECs. (Circulation.

To compare the diagnostic value of dobutamine stress echocardiography with dipyridamole thallium-201 single-photon emission computed tomography (SPECT) in detecting coronary artery disease (CAD), we performed both tests on 54 patients who also underwent coronary arteriography. Dobutamine was infused at an incremental regimen of 5, 10, 20, 30 and 40 micrograms.kg-1.min-1. Dipyridamole was infused at a rate of 0.14 mg.kg-1.min-1 over 4 min. Dobutamine stress echocardiography detected 40 (93%) and SPECT 42 (98%, P = ns) of the 43 patients with significant CAD, defined as > or = 50% diameter stenosis. The specificity was 73% (8 of 11) for both tests. The sensitivity for detecting individual coronary artery stenosis with dobutamine stress echocardiography was 81% (30 of 37) for the left anterior descending artery, 75% (24 of 32) for the right coronary artery, and 61% (17 of 28) for the left circumflex artery. For SPECT it was 89%, 97% (P < 0.05 vs dobutamine stress echocardiography) and 75%, respectively. Among the 97 stenotic coronary arteries, 17 had mild to moderate stenosis (50%-69% diameter stenosis) and 80 had severe stenosis (> or = 70% diameter stenosis). With dobutamine stress echocardiography, 53% of the arteries with mild to moderate stenosis were identified vs 78% of those with severe stenosis (P < 0.05). With SPECT, the sensitivity was 82% (14 of 17) in mild to moderate stenosis and 89% (71 of 80) in severe stenosis (P = ns). No major side effects occurred during either test. Thus, both dobutamine stress and SPECT are highly sensitive for detection and localization of CAD.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperglycemia is a major cause of diabetic vascular disease. High glucose can induce reactive oxygen species (ROS) and nitric oxide (NO) generation, which can subsequently induce endothelial dysfunction. High glucose is also capable of triggering endothelial cell apoptosis. Little is known about the molecular mechanisms and the role of ROS and NO in high glucose-induced endothelial cell apoptosis. This study was designed to determine the involvement of ROS and NO in high glucose-induced endothelial cell apoptosis. Expression of endothelial nitric oxide synthase (eNOS) protein and apoptosis were studied in cultured human umbilical vein endothelial cells (HUVECs) exposed to control-level (5.5 mM) and high-level (33 mM) glucose at various periods (e.g., 2, 12, 24, 48 h). We also examined the effect of high glucose on H 2 O 2 production using flow cytometry. The results showed that eNOS protein expression was up-regulated by high glucose exposure for 2-6 h and gradually reduced after longer exposure in HUVECs. H 2 O 2 production and apoptosis, which can be reversed by vitamin C and NO donor (sodium nitroprusside), but enhanced by NOS inhibitor (N G -nitro-L-arginine methyl ether), were collated to a different time course (24-48 h) to HUVECs. These results provide the molecular basis for understanding that NO plays a protective role from apoptosis of HUVECs during the early stage (Ͻ24 h) of high glucose exposure, but in the late stage (Ͼ24 h), high glucose exposure leads to the imbalance of NO and ROS, resulting to the observed apoptosis. This may explain, at least in part, the impaired endothelial function and vascular complication of diabetic mellitus that would occur at late stages.

Hyperglycemia is a major cause of diabetic vascular disease. High glucose can induce reactive oxygen species (ROS) and nitric oxide (NO) generation, which can subsequently induce endothelial dysfunction. High glucose is also capable of triggering endothelial cell apoptosis. Little is known about the molecular mechanisms and the role of ROS and NO in high glucose-induced endothelial cell apoptosis. This study was designed to determine the involvement of ROS and NO in high glucose-induced endothelial cell apoptosis. Expression of endothelial nitric oxide synthase (eNOS) protein and apoptosis were studied in cultured human umbilical vein endothelial cells (HUVECs) exposed to control-level (5.5 mM) and high-level (33 mM) glucose at various periods (e.g., 2, 12, 24, 48 h). We also examined the effect of high glucose on H(2)O(2) production using flow cytometry. The results showed that eNOS protein expression was up-regulated by high glucose exposure for 2-6 h and gradually reduced after longer exposure in HUVECs. H(2)O(2) production and apoptosis, which can be reversed by vitamin C and NO donor (sodium nitroprusside), but enhanced by NOS inhibitor (N(G)-nitro-L-arginine methyl ether), were collated to a different time course (24-48 h) to HUVECs. These results provide the molecular basis for understanding that NO plays a protective role from apoptosis of HUVECs during the early stage (<24 h) of high glucose exposure, but in the late stage (>24 h), high glucose exposure leads to the imbalance of NO and ROS, resulting to the observed apoptosis. This may explain, at least in part, the impaired endothelial function and vascular complication of diabetic mellitus that would occur at late stages.