다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

For a long time, superoxide generation by an NADPH oxidase was considered as an oddity only found in professional phagocytes. Over the last years, six homologs of the cytochrome subunit of the phag...

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The NOX Family of ROS-Generating NADPH Oxidases: Physiology and Pathophysiology

The discovery that mammalian cells have the ability to synthesize the free radical nitric oxide (NO) has stimulated an extraordinary impetus for scientific research in all the fields of biology and medicine. Since its early description as an endothelial-derived relaxing factor, NO has emerged as a fundamental signaling device regulating virtually every critical cellular function, as well as a potent mediator of cellular damage in a wide range of conditions. Recent evidence indicates that most of the cytotoxicity attributed to NO is rather due to peroxynitrite, produced from the diffusion-controlled reaction between NO and another free radical, the superoxide anion. Peroxynitrite interacts with lipids, DNA, and proteins via direct oxidative reactions or via indirect, radical-mediated mechanisms. These reactions trigger cellular responses ranging from subtle modulations of cell signaling to overwhelming oxidative injury, committing cells to necrosis or apoptosis. In vivo, peroxynitrite generation represents a crucial pathogenic mechanism in conditions such as stroke, myocardial infarction, chronic heart failure, diabetes, circulatory shock, chronic inflammatory diseases, cancer, and neurodegenerative disorders. Hence, novel pharmacological strategies aimed at removing peroxynitrite might represent powerful therapeutic tools in the future. Evidence supporting these novel roles of NO and peroxynitrite is presented in detail in this review.

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Nitric Oxide and Peroxynitrite in Health and Disease

Spike (S) proteins of coronaviruses, including the coronavirus that causes severe acute respiratory syndrome (SARS), associate with cellular receptors to mediate infection of their target cells Here we identify a metallopeptidase, angiotensin-converting enzyme 2 (ACE2), isolated from SARS coronavirus (SARS-CoV)-permissive Vero E6 cells, that efficiently binds the S1 domain of the SARS-CoV S protein We found that a soluble form of ACE2, but not of the related enzyme ACE1, blocked association of the S1 domain with Vero E6 cells 293T cells transfected with ACE2, but not those transfected with human immunodeficiency virus-1 receptors, formed multinucleated syncytia with cells expressing S protein Furthermore, SARS-CoV replicated efficiently on ACE2-transfected but not mock-transfected 293T cells Finally, anti-ACE2 but not anti-ACE1 antibody blocked viral replication on Vero E6 cells Together our data indicate that ACE2 is a functional receptor for SARS-CoV

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Angiotensin-converting enzyme 2 is a functional receptor for the SARS coronavirus.

Nitric oxide is the major endothelium-derived relaxing factor (EDRF), and it is thought to relax smooth muscle cells by stimulation of guanylate cyclase, accumulation of its product cyclic GMP, and cGMP-dependent modification of several intracellular processes, including activation of potassium channels through cGMP-dependent protein kinase. Here we present evidence that both exogenous nitric oxide and native EDRF can directly activate single Ca(2+)-dependent K+ channels (K+Ca) in cell-free membrane patches without requiring cGMP. Under conditions when guanylate cyclase was inhibited by methylene blue, considerable relaxation of rabbit aorta to nitric oxide persisted which was blocked by charybdotoxin, a specific inhibitor of K+Ca channels. These studies demonstrate a novel direct action of nitric oxide on K+Ca channels.

Nitric oxide directly activates calcium-dependent potassium channels in vascular smooth muscle

Oxidative stress has been implicated in the pathophysiology of myocardial failure. We tested the hypothesis that oxidative stress can regulate extracellular matrix in cardiac fibroblasts. Neonatal ...

Oxidative stress regulates collagen synthesis and matrix metalloproteinase activity in cardiac fibroblasts.

We previously reported enhanced expression of the p67 phox and gp91 phox components of NAD(P)H oxidase in angiotensin (Ang) II–induced hypertension, suggesting de novo assembly in response to Ang II. To examine the direct involvement of NAD(P)H oxidases in Ang II–induced O 2 − production, we designed a chimeric peptide that inhibits p47 phox association with gp91 phox in NAD(P)H oxidase (gp91ds- tat ). This was achieved by linking a 9-amino acid peptide (aa) derived from HIV-coat protein ( tat ) to a 9-aa sequence of gp91 phox (known to interact with p47 phox ). As a control, we constructed a chimera containing tat and a scrambled gp91 sequence (scramb- tat ). We found that gp91ds- tat decreased O 2 − levels in aortic rings treated with Ang II (10 pmol/L) but had no effect on either the O 2 − -generating enzyme xanthine oxidase or potassium superoxide–generated O 2 − . We infused vehicle, Ang II (0.75 mg · kg −1 · d −1 ), Ang II+gp91ds- tat (10 mg · kg −1 · d −1 ), or Ang II+scramb- tat intraperitoneally in C57Bl/6 mice and measured systolic blood pressure (SBP) on days 0, 3, 5, and 7 of infusion. SBP increased by day 3 in mice given Ang II and Ang II+scramb- tat but was significantly lower with Ang II+gp91- tat . On day 7, SBP was still significantly inhibited in mice given Ang II+gp91ds- tat , whereas Ang II–induced O 2 − production was inhibited throughout the aorta as detected by dihydroethidium staining, consistent with the ability of this inhibitor to block the various vascular NAD(P)H oxidase isoforms. These data support the hypothesis that inhibition of the interaction of p47 phox and gp91 phox (or its homologues) can block O 2 − production and attenuate blood pressure elevation in mice.

Novel Competitive Inhibitor of NAD(P)H Oxidase Assembly Attenuates Vascular O2− and Systolic Blood Pressure in Mice

A major source of vascular smooth muscle cell (VSMC) superoxide is NAD(P)H oxidase. However, the molecular characteristics and regulation of this enzyme are unclear. We investigated whether VSMCs from human resistance arteries (HVSMCs) possess a functionally active, angiotensin II (Ang II)–regulated NAD(P)H oxidase that contains neutrophil oxidase subunits, including p22phox, gp91phox, p40phox, p47phox, and p67phox. mRNA expression of gp91phox homologues, nox1 and nox4, was also assessed in HVSMCs, human aortic smooth muscle cells, and rat VSMCs. HVSMCs were obtained from resistance arteries from gluteal biopsies of healthy subjects. gp91phox and nox4, but not nox1, were detected in HVSMCs. Nox1 and nox4, but not gp91phox, were expressed in human aortic smooth muscle cells and rat VSMCs. All NAD(P)H oxidase subunits were present in HVSMCs as detected by reverse transcriptase–polymerase chain reaction and immunoblotting. Ang II increased NAD(P)H oxidase subunit abundance. These effects were inhibited by cycloheximide. Acute Ang II stimulation (10 to 15 minutes) increased p47phox serine phosphorylation and induced p47phox and p67phox translocation. This was associated with NAD(P)H oxidase activation. In cells transfected with gp91phox antisense oligonucleotides, Ang II–mediated actions were abrogated. NADPH-induced superoxide generation was reduced by gp91ds-tat and apocynin, inhibitors of p47phox-gp91phox interactions. Our results suggest that HVSMCs possess a functionally active gp91phox-containing neutrophil-like NAD(P)H oxidase. Ang II regulates the enzyme by inducing phosphorylation of p47phox, translocation of cytosolic subunits, and de novo protein synthesis. These novel findings provide insight into the molecular regulation of NAD(P)H oxidase by Ang II in HVSMCs. Furthermore, we identify differences in gp91phox homologue expression in VSMCs from rats and human small and large arteries.

Expression of a functionally active gp91phox-containing neutrophil-type NAD(P)H oxidase in smooth muscle cells from human resistance arteries: regulation by angiotensin II.

We previously reported enhanced expression of the p67 phox and gp91 phox components of NAD(P)H oxidase in angiotensin (Ang) II-induced hypertension, suggesting de novo assembly in response to Ang II. To examine the direct involvement of NAD(P)H oxidases in Ang II-induced O 2 - production, we designed a chimeric peptide that inhibits p47 phox association with gp91 phox in NAD(P)H oxidase (gp91ds-tat). This was achieved by linking a 9-amino acid peptide (aa) derived from HIV-coat protein (tat) to a 9-aa sequence of gp91 phox (known to interact with p47 phox ). As a control, we constructed a chimera containing tat and a scrambled gp91 sequence (scramb-tat). We found that gp91ds-tat decreased O 2 - levels in aortic rings treated with Ang II (10 pmol/L) but had no effect on either the O 2 - -generating enzyme xanthine oxidase or potassium superoxide-generated O 2 - . We infused vehicle, Ang II (0.75 mg kg -1 . d -1 ), Ang II+gp91ds-tat (10 mg.kg -1 . d -1 ), or Ang II+scramb-tat intraperitoneally in C57B1/6 mice and measured systolic blood pressure (SBP) on days 0, 3, 5, and 7 of infusion. SBP increased by day 3 in mice given Ang II and Ang II+scramb-tat but was significantly lower with Ang II+gp91-tat. On day 7, SBP was still significantly inhibited in mice given Ang II+gp91ds-tat, whereas Ang II-induced O 2 - production was inhibited throughout the aorta as detected by dihydroethidium staining, consistent with the ability of this inhibitor to block the various vascular NAD(P)H oxidase isoforms. These data support the hypothesis that inhibition of the interaction of p47 phox and gp91 phox (or its homologues) can block O 2 - production and attenuate blood pressure elevation in mice.

Patrick J. Pagano

Papers

Nitric oxide directly activates calcium-dependent potassium channels in vascular smooth muscle

Oxidative stress regulates collagen synthesis and matrix metalloproteinase activity in cardiac fibroblasts.

Novel Competitive Inhibitor of NAD(P)H Oxidase Assembly Attenuates Vascular O2− and Systolic Blood Pressure in Mice

Expression of a functionally active gp91phox-containing neutrophil-type NAD(P)H oxidase in smooth muscle cells from human resistance arteries: regulation by angiotensin II.

Novel competitive inhibitor of NAD(P)H oxidase assembly attenuates vascular O2- and systolic blood pressure in mice