Toyohiko Yokoi

Apoptosis Signal-Regulating Kinase 1 Mediates Cellular Senescence Induced by High Glucose in Endothelial Cells

Vascular ageing is accelerated in patients with diabetes. However, the underlying mechanism remains unclear. Here, we show that high glucose induces activation of apoptosis signal-regulating kinase 1 (ASK1), an apoptosis-inducing signal that mediates endothelial cell senescence induced by hyperglycemia. High glucose induced a time-dependent increase in the levels of ASK1 expression and its activity in human umbilical vein endothelial cells (HUVECs). Incubation of endothelial cells with high glucose increased the proportion of cells expressing senescence-associated β-galactosidase (SA-β-gal) activity. However, transfection with an adenoviral construct including a dominant negative form of ASK1 gene significantly inhibited SA-β-gal activity induced by high glucose. In addition, infection with an adenoviral construct expressing the constitutively active ASK1 gene directly induced an increase in the levels of SA-β-gal activity. Activation of the ASK1 signal also enhanced plasminogen activator inhibitor-1 (PAI-1) expression in HUVECs. Induction of senescent endothelial cells in aortas and elevation of plasma PAI-1 levels were observed in streptozotocin (STZ) diabetic mice, whereas these changes induced by STZ were attenuated in ASK1-knockout mice. Our results suggest that hyperglycemia accelerates endothelial cell senescence and upregulation of PAI-1 expression through activation of the ASK1 signal. Thus, ASK1 may be a new therapeutic target to prevent vascular ageing and thrombosis in diabetic patients.

Homocysteine Enhances Endothelial Apoptosis via Upregulation of Fas-Mediated Pathways

Hyperhomocysteinemia is an independent risk factor for the development of atherosclerosis. However, the underlying mechanism of endothelial cell injury in hyperhomocysteinemia has not been elucidated. In this study, we examined the effect of homocysteine (Hcy) on Fas-mediated apoptosis in endothelial cells. Hcy-induced upregulation of Fas in endothelial cells (ECs) in a dose-dependent manner. At the same time, Hcy increased intracellular peroxide in ECs. Hcy-induced Fas expression was inhibited by the treatment with catalase. Hcy increased NF-κinding activity, and adenovirus-mediated transfection of a I κ-B mutant (Iκ-B mt) gene inhibited Hcy-induced Fas expression. ECs were sensitive to Fas-mediated apoptosis when exposed to Hcy. Under these condition, Iκ-B mt protected ECs from Fas-mediated apoptosis. In addition, Hcy inhibited expression of the caspase-8 inhibitor FLICE-inhibitory protein (FLIP). Adenovirus-mediated transfection of constitutively active Akt gene abolished the Hcy-mediated downregulation of FLIP. These data suggest that upregulation of Fas expression and downregulation of FLIP is a mechanism through which Hcy induces EC apoptosis.

Hepatocyte Growth Factor, but not Vascular Endothelial Growth Factor, Attenuates Angiotensin II–Induced Endothelial Progenitor Cell Senescence

Although both hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) are potent angiogenic growth factors in animal models of ischemia, their characteristics are not the same in animal experiments and clinical trials. To elucidate the discrepancy between HGF and VEGF, we compared the effects of HGF and VEGF on endothelial progenitor cells under angiotensin II stimulation, which is a well-known risk factor for atherosclerosis. Here, we demonstrated that HGF, but not VEGF, attenuated angiotensin II–induced senescence of endothelial progenitor cells through a reduction of oxidative stress by inhibition of the phosphatidylinositol-3,4,5-triphosphate/rac1 pathway. Potent induction of neovascularization of endothelial progenitor cells by HGF, but not VEGF, under angiotensin II was also confirmed by in vivo experiments using several models, including HGF transgenic mice.

Fas Signaling Induces Akt Activation and Upregulation of Endothelial Nitric Oxide Synthase Expression

Abstract—A growing body of evidence has shown that Fas, a death receptor, mediates apoptosis-unrelated biological effects. Here, we report that Fas engagement with Fas ligand induced activation of Akt and upregulation of endothelial nitric oxide synthase expression without induction of apoptosis. In the presence of the phosphatidylinositol 3-kinase inhibitor wortmannin, Fas ligand, however, induced apoptosis instead of upregulation of endothelial nitric oxide synthase expression. In vivo, systolic blood pressure was slightly higher in mutant mice with decreased cell surface Fas expression (lpr mice) compared with wild-type mice. In addition, chronic inhibition of nitric oxide synthesis by NG-nitro-l-arginine induced a progressive increase in the levels of blood pressure in wild-type mice, whereas no further increase in the levels of blood pressure was observed in lpr mice. Furthermore, acetylcholine caused a lesser endothelium-dependent relaxation of the strips from lpr mice compared with wild-type mice, although the vasoconstrictor potency of phenylephrine was not different between the two groups. These findings indicate that Fas signaling may have a role in the regulation of endothelial function and blood pressure through modulating endothelial nitric oxide synthase expression in the Akt signal-dependent manner.

Validation of two automatic devices: Omron HEM-7252G-HP and Omron HEM-7251G for self-measurement of blood pressure according to the European Society of Hypertension International Protocol revision 2010.

ObjectiveThe aim of this study was to validate the performance of Omron HEM-7252G-HP and Omron HEM-7251G for monitoring upper arm blood pressure (BP) in accordance with the European Society of Hypertension International Protocol revision 2010 (ESH-IP revision 2010). MethodsThree trained medical doctors validated the performance of these devices by comparing data obtained from these devices with those obtained using a standard mercury sphygmomanometer. We included 33 participants (19 men and 14 women for the experiment using HEM-7252G-HP; 16 men and 17 women for the experiment using HEM-7251G). The mean age of the participants was 50±12 and 53±10 years in the respective studies. ResultsThe percentages of test device–observer mercury sphygmomanometer BP differences within 5, 10, and 15 mmHg were 76, 92, and 97% for systolic BP (SBP) and 83, 97, and 99% for diastolic BP (DBP), respectively, in the Omron HEM-7252G-HP and 77, 92, and 99% for SBP and 85, 94, and 98% for DBP, respectively, in the Omron HEM-7251G in the part 1 analysis; both SBP and DBP passed the part 1 and part 2 criteria.The mean differences between the device and mercury readings for SBP and DBP were as follows: HEM-7252G-HP, −1.5±5.1 and −1.2±3.9 mmHg, respectively; HEM-7351G, −0.6±4.7 and −0.2±4.4 mmHg, respectively. ConclusionThe Omron HEM-7252G-HP and HEM-7251G passed all the requirements of the ESH-IP 2010 revision.

Validation of Omron RS8, RS6, and RS3 home blood pressure monitoring devices, in accordance with the European Society of Hypertension International Protocol revision 2010.

Background Allowing patients to measure their blood pressure at home is recognized as being of clinical value. However, it is not known how often these measurements are taken correctly. Blood pressure monitors for home use fall into two types based on the position of the cuff, ie, at the upper arm or the wrist. The latter is particularly convenient, as measurements can be taken fully clothed. This study aimed to evaluate the performance of the wrist-type blood pressure monitors Omron RS8 (HEM-6310F-E), Omron RS6 (HEM-6221-E), and Omron RS3 (HEM-6130-E). Methods A team of three trained doctors validated the performance of these devices by comparing the measurements obtained from these devices with those taken using a standard mercury sphygmomanometer. All the devices met the validation requirements of the European Society of Hypertension International Protocol revision 2010. Results The difference in blood pressure readings between the tested device and the standard mercury sphygmomanometer was within 3 mmHg, which is acceptable according to the European Society of Hypertension guidelines. Conclusion All the home devices tested were found to be suitable for measuring blood pressure at home because their performance fulfilled the requirement of the guidelines.

Validation of home blood pressure-monitoring devices, Omron HEM-1020 and Omron i-Q132 (HEM-1010-E), according to the European Society of Hypertension International Protocol.

ObjectiveAllowing patients to measure their blood pressure (BP) at home is recognized as being of clinical value. However, it is not known whether BP measurement is usually taken correctly outside of a clinical setting. Automated proper wrapping of the cuff and correction of wrong posture will help in taking BP measurement properly. This study aimed to evaluate the performance of the Omron HEM-1020 and the Omron i-Q132 devices, which are equipped with those functions. MethodsA team of three trained doctors validated the performance of these devices by comparing data obtained from both devices with those from a standard mercury sphygmomanometer. Both devices passed the validation requirements of the European Society of Hypertension International Protocol. The magnitude of the difference in BP readings between the tested device and the standard mercury sphygmomanometer was within the range of ±3 mmHg, which is allowed by the European Society of Hypertension guidelines. ConclusionBoth the Omron HEM-1020 and the Omron i-Q132 devices were found to be useful for measuring BP at home because their performance fulfilled the requirement of the guidelines.

Fas Ligand mRNA Levels of Circulating Leukocytes Reflect Endothelial Dysfunction in Hyperlipidemic but Not in Non-Hyperlipidemic Patients

To find a novel marker for identifying patients at high-risk for endothelial dysfunction among patients with atherosclerosis, we examined the correlation between mRNA levels of Fas ligand (FasL), an apoptosis-inducing factor, in circulating leukocytes and clinical parameters in these patients. FasL mRNA levels of circulating leukocytes were measured with the TaqMan-PCR method. A negative correlation was observed between brachial artery flow-mediated dilatation (%FMD) and FasL mRNA levels of leukocytes in hyperlipidemic but not in non-hyperlipidemic patients. %FMD was more impaired in patients with a high level of FasL mRNA than in those with a low level of FasL mRNA. Interestingly, the improvement of %FMD by treatment with a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (simvastatin) was greater in the group showing a decrease in FasL mRNA than in the group with no such decrease. Additionally, simvastatin suppressed the FasL mRNA expression in leukocytes and decreased plasma oxidized low-density lipoprotein (OxLDL) levels. Furthermore, the supernatant of cultured leukocytes from hyperlipidemic patients induced cell death in Jurkat T cells, which was neutralized by an antibody against FasL. These findings suggest that high FasL mRNA expression in circulating leukocytes may be a marker of high-risk for endothelial dysfunction in hyperlipidemic but not in non-hyperlipidemic patients. This information may provide a novel basis for targeting of statin therapy in patients with vulnerable plaques.

Validation of three automatic devices for the self-measurement of blood pressure according to the European Society of Hypertension International Protocol revision 2010: the Omron HEM-7130, HEM-7320F, and HEM-7500F.

ObjectiveThe aim of the present study was to validate the Omron HEM-7130, HEM-7320F, and HEM-7500F for monitoring upper arm blood pressure (BP) according to the European Society of Hypertension International Protocol revision 2010 (ESH-IP revision 2010). MethodsThree trained medical doctors validated the performance of these devices by comparing the data obtained from the devices with those of a standard mercury sphygmomanometer. We included 33 participants (20 men and 13 women for the HEM-7130 experiment; 18 men and 15 women for the HEM-7320F experiment; and 21 men and 12 women for the HEM-7500F experiment). The mean age of the participants was 49±15, 50±11, and 50±11 years in the respective studies. ResultsThe mean differences between the device and the mercury readings for systolic and diastolic BP were as follows: HEM-7130, −1.8±5.3 and −0.1±4.0 mmHg, respectively; HEM-7320F, −0.9±4.7 and −1.9±4.4 mmHg, respectively; and HEM-7500F, −1.0±4.6 and −1.1±4.0 mmHg, respectively. These findings indicated that the device was reading lower than the mercury. However, the number of absolute differences between the devices and observers fulfilled the requirement of the ESH-IP revision 2010. ConclusionThe Omron HEM-7130, HEM-7320F, and HEM-7500F passed all the requirements of the ESH-IP 2010 revision. Therefore, we recommend these devices for the home measurement of BP in adults.

Validation of two automatic devices for the self-measurement of blood pressure according to the ANSI/AAMI/ISO81060-2:2009 guidelines: the Omron BP765 (HEM-7311-ZSA) and the Omron BP760N (HEM-7320-Z)

Background Allowing patients to measure their blood pressure (BP) at home will be the standard for evaluating the disease state as the process of clinical diagnosis, and it is recognized as having great clinical utility. To measure BP as accurately as possible, innovative techniques have been incorporated into home BP measurement devices. Objective The present study aimed to evaluate the performance of the Omron BP765 (HEM-7311-ZSA) and the Omron BP760N (HEM-7320-Z), which are equipped with functions to detect irregular pulses and arm movement that lead to inaccurate BP readings. Methods A team of three trained medical doctors validated the performance of these devices by comparing the data alternatively obtained from both devices with those from a standard mercury sphygmomanometer. Results The magnitude of the difference in BP readings between the tested device and the standard mercury sphygmomanometer in the Omron BP765 and BP760N was within the range of ±3 mmHg (mean) allowed by the American National Standards Institute, Inc/Association for the Advancement of Medical Instrumentation/International Organization for Standardization (ANSI/AAMI/ISO) 81060-2:2009 guidelines. Conclusion The Omron BP765 and BP760N were found useful for the self-measurement of BP at home, and their performance fulfilled the requirement of the ANSI/AAMI/ISO 81060-2:2009 guidelines.