Discussion for H

Nonsingular H-matrices and positive stable matrices play an important role in the stability of neural network system. In this paper, some criteria for nonsingular H-matrices are obtained by the theory of diagonally dominant matrices and the obtained result is introduced into identifying the stability of neural networks. So the criteria for nonsingular H-matrices are expanded and their application on neural network system is given. Finally, the effectiveness of the results is illustrated by numerical examples

Activation of G protein-coupled estrogen receptor 1 induces coronary artery relaxation via Epac/Rap1-mediated inhibition of RhoA/Rho kinase pathway in parallel with PKA

Previously, we reported that cAMP/PKA signaling is involved in GPER-mediated coronary relaxation by activating MLCP via inhibition of RhoA pathway. In the current study, we tested the hypothesis that activation of GPER induces coronary artery relaxation via inhibition of RhoA/Rho kinase pathway by cAMP downstream targets, exchange proteins directly activated by cAMP (Epac) as well as PKA. Our results show that Epac inhibitors, brefeldin A (BFA, 50 μM), or ESI-09 (20 μM), or CE3F4 (100 μM), all partially inhibited porcine coronary artery relaxation response to the selective GPER agonist, G-1 (0.3-3 μM); while concurrent administration of BFA and PKI (5 μM), a PKA inhibitor, almost completely blocked the relaxation effect of G-1. The Epac specific agonist, 8-CPT-2Me-cAMP (007, 1-100 μM), induced a concentration-dependent relaxation response. Furthermore, the activity of Ras-related protein 1 (Rap1) was up regulated by G-1 (1 μM) treatment of porcine coronary artery smooth muscle cells (CASMCs). Phosphorylation of vasodilator-stimulated phosphoprotein (p-VASP) was elevated by G-1 (1 μM) treatment, but not by 007 (50 μM); and the effect of G-1 on p-VASP was blocked by PKI, but not by ESI-09, an Epac antagonist. RhoA activity was similarly down regulated by G-1 and 007, whereas ESI-09 restored most of the reduced RhoA activity by G-1 treatment. Furthermore, G-1 decreased PGF2α-induced p-MYPT1, which was partially reversed with either ESI-09 or PKI; whereas, concurrent administration of ESI-09 and PKI totally prevented the inhibitory effect of G-1. The inhibitory effects of G-1 on p- MLC levels in CASMCs were mostly restored by either ESI-09 or PKI. These results demonstrate that activation of GPER induces coronary artery relaxation via concurrent inhibition of RhoA/Rho kinase by Epac/Rap1 and PKA. GPER could be a potential drug target for preventing and treating cardiovascular diseases

Activation of GPER Induces Differentiation and Inhibition of Coronary Artery Smooth Muscle Cell Proliferation

BACKGROUND: Vascular pathology and dysfunction are direct life-threatening outcomes resulting from atherosclerosis or vascular injury, which are primarily attributed to contractile smooth muscle cells (SMCs) dedifferentiation and proliferation by re-entering cell cycle. Increasing evidence suggests potent protective effects of G-protein coupled estrogen receptor 1 (GPER) activation against cardiovascular diseases. However, the mechanism underlying GPER function remains poorly understood, especially if it plays a potential role in modulating coronary artery smooth muscle cells (CASMCs). METHODOLOGY/PRINCIPAL FINDINGS: The objective of our study was to understand the functional role of GPER in CASMC proliferation and differentiation in coronary arteries using from humans and swine models. We found that the GPER agonist, G-1, inhibited both human and porcine CASMC proliferation in a concentration- (10(−8) to 10(−5) M) and time-dependent manner. Flow cytometry revealed that treatment with G-1 significantly decreased the proportion of S-phase and G2/M cells in the growing cell population, suggesting that G-1 inhibits cell proliferation by slowing progression of the cell cycle. Further, G-1-induced cell cycle retardation was associated with decreased expression of cyclin B, up-regulation of cyclin D1, and concomitant induction of p21, and partially mediated by suppressed ERK1/2 and Akt pathways. In addition, G-1 induces SMC differentiation evidenced by increased α-smooth muscle actin (α-actin) and smooth muscle protein 22α (SM22α) protein expressions and inhibits CASMC migration induced by growth medium. CONCLUSION: GPER activation inhibits CASMC proliferation by suppressing cell cycle progression via inhibition of ERK1/2 and Akt phosphorylation. GPER may constitute a novel mechanism to suppress intimal migration and/or synthetic phenotype of VSMC

hElp3 Directly Modulates the Expression of HSP70 Gene in HeLa Cells via HAT Activity

Human Elongator complex, which plays a key role in transcript elongation in vitro assay, is incredibly similar in either components or function to its yeast counterpart. However, there are only a few studies focusing on its target gene characterization in vivo. We studied the effect of down-regulation of the human elongation protein 3 (hELP3) on the expression of HSP70 through antisense strategy. Transfecting antisense plasmid p1107 into HeLa cells highly suppressed hELP3 expression, and substantially reduced expression of HSP70 mRNA and protein. Furthermore, chromatin immunoprecipitation assay (ChIP Assay) revealed that hElp3 participates in the transcription elongation of HSPA1A in HeLa cells. Finally, complementation and ChIP Assay in yeast showed that hElp3 can not only complement the growth and slow activation of HSP70 (SSA3) gene transcription, but also directly regulates the transcription of SSA3. On the contrary, these functions are lost when the HAT domain is deleted from hElp3. These data suggest that hElp3 can regulate the transcription of HSP70 gene, and the HAT domain of hElp3 is essential for this function. These findings now provide novel insights and evidence of the functions of hELP3 in human cells

2023 AHA data upload-raw & analysis.zip

In collecting these data, we applied isometric tension study, western blot techniques, and enzyme-linked immunosorbent assay to porcine coronary artery rings and the culture's primary coronary artery smooth muscle cells.</p

G-protein-coupled estrogen receptor as a new therapeutic target for treating coronary artery disease.

Coronary heart disease (CHD) continues to be the greatest mortality risk factor in the developed world. Estrogens are recognized to have great therapeutic potential to treat CHD and other cardiovascular diseases; however, a significant array of potentially debilitating side effects continues to limit their use. Moreover, recent clinical trials have indicated that long-term postmenopausal estrogen therapy may actually be detrimental to cardiovascular health. An exciting new development is the finding that the more recently discovered G-protein-coupled estrogen receptor (GPER) is expressed in coronary arteries-both in coronary endothelium and in smooth muscle within the vascular wall. Accumulating evidence indicates that GPER activation dilates coronary arteries and can also inhibit the proliferation and migration of coronary smooth muscle cells. Thus, selective GPER activation has the potential to increase coronary blood flow and possibly limit the debilitating consequences of coronary atherosclerotic disease. This review will highlight what is currently known regarding the impact of GPER activation on coronary arteries and the potential signaling mechanisms stimulated by GPER agonists in these vessels. A thorough understanding of GPER function in coronary arteries may promote the development of new therapies that would help alleviate CHD, while limiting the potentially dangerous side effects of estrogen therapy

PGE2 action in human coronary artery smooth muscle: Role of potassium channels and signaling cross-talk

Cyclic AMP-stimulating agents are powerful vasodilators, but our knowledge of the signal transduction mechanisms of these agents, particularly in human arteries, is limited. We now report direct molecular effects of prostaglandin E2 (PGE2) on cultured human coronary artery smooth muscle cells (HCASMC). Patch-clamp studies revealed that 10 μM PGE2 opens a high-conductance (∼200 pS), calcium-stimulated potassium (BKCa) channel in intact HCASMC. In contrast, PGE2 had no direct effect on channels in cell-free patches, indicating involvement of a soluble second messenger. Enzyme immunoassay demonstrated that PGE2 enhances production of cAMP in HCASMC, but does not increase [cGMP]. Furthermore, forskolin, CPT-cAMP, or CPT-cGMP mimicked the stimulatory effect of PGE2 on BKCa channel activity. Interestingly, the response to PGE2 was unaffected by inhibiting the cAMP-dependent protein kinase, but was antagonized by inhibitors of the cGMP-dependent protein kinase (PKG). Furthermore, cAMP-stimulated PKG activity mimicked the effect of PGE2. These studies suggest a novel PGE2 action in human arteries: opening of BKCa channels via cAMP cross-activation of PKG in HCASMC. It is proposed that this signaling mechanism may mediate the vasodilatory response to cAMP-dependent agents in the human coronary and other vascular beds. Copyright © 2002 S. Karger AG, Basel

Dopamine relaxes porcine coronary arteries and stimulates potassium channel activity in porcine coronary arterial smooth muscle cells

The relaxing effect of dopamine on isolated coronary vessels and the activating effect of dopamine on large-conductance, calcium-activated potassium channels (BKCa) in the membrane of coronary myocytes were investigated with isometric tension recording method and patch-clamp technique. Tension studies demonstrated that dopamine relaxed prostaglandin F2α-induced contraction of porcine coronary arteries in a concentration-dependent manner, but it failed to relax high [K+] precontracted arteries. In cell attached patch experiments, dopamine caused a significant increase in the mean opening probability of the BKCa channels. The effect of dopamine was not blocked by propranolol but was completely prevented by SCH23390, a selective DA1 antagonist. These results demonstrate that dopamine relaxes prostaglandin F2α-induced contraction of porcine coronary arteries via activation of DA1 receptors which causes stimulation of BKCa channel activity

Relationship of Oxidative Stress with Cardiovascular Disease

More women die from complications related to cardiovascular disease (CVD) each year than men, yet dysfunction of the heart and blood vessels is still often considered to be primarily a “male” health issue. Emerging data indicate that oxidative stress is an important etiological factor for CVD in women, and it is apparent that female hormones, like estrogen, exert powerful influences on oxidative balance. This chapter will present recent findings and current concepts concerning oxidative stress and cardiovascular function in women. Prominent sources of oxidants in the heart and vasculature will be discussed (e.g., NADPH oxidase, xanthine oxidase (XO) , mitochondria, and uncoupled NOS), as well as the effect of estrogen on activity and expression of these proteins in the context of normal hormonal levels and exogenous estrogen replacement therapy. We will also discuss three prominent CVDs that exhibit a rather marked—and at times, surprising—sexual dimorphism in their epidemiology, and consider the ability of estrogen to influence the development and progression of these pathophysiological states in terms of cellular/molecular mechanisms. The overall goal of the chapter is to provide the reader with a rather comprehensive overview of how oxidative stress impacts women’s cardiovascular health, and to review the potential role of estrogen as both a preventive and causative factor in CVD among women

Estrogen and oxidative stress: A novel mechanism that may increase the risk for cardiovascular disease in women

Although early studies demonstrated that exogenous estrogen lowered a woman\u27s risk of cardiovascular disease, recent trials indicate that HRT actually increases the risk of coronary heart disease or stroke. However, there is no clear explanation for this discrepancy. Is estrogen a helpful or a harmful hormone in terms of cardiovascular function? This review discusses some recent findings that propose a novel mechanism which may shed significant light upon this controversy. We propose that nitric oxide synthase (NOS) expressed within the vascular wall is a target of estrogen action. Under normal conditions in younger women, the primary product of estrogen action is NO, which produces a number of beneficial effects on vascular biology. As a woman ages, however, there is evidence for loss of important molecules essential for NO production (e.g., tetrahydrobiopterin, l-arginine). As these molecules are depleted, NOS becomes increasingly uncoupled from NO production, and instead produces superoxide, a dangerous reactive oxygen species. We propose that a similar uncoupling and reversal of estrogen response occurs in diabetes. Therefore, we propose that estrogen is neither good nor bad , but simply stimulates NOS activity. It is the biochemical environment around NOS that will determine whether estrogen produces a beneficial (NO) or deleterious (superoxide) product, and can account for this dual and opposite nature of estrogen pharmacology. Further, this molecular mechanism is consistent with recent analyses revealing that HRT produces salutary effects in younger women, but mainly increases the risk of cardiovascular dysfunction in older postmenopausal women