Abstract 1516: Role of Oxidative Stress in Atrial Tachycardia Remodelling

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Xiao-Yan Qi ◽  
Louis R Villeneuve ◽  
Balazs Ordog ◽  
Denis Chartier ◽  
David R Van Wagoner ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Atrial Tachycardia ◽  
Potential Role ◽  
Oxidant Stress ◽  
Cell Voltage ◽  
Radical Generation ◽  
X 24 ◽  
Camkii Activation

Atrial tachycardia remodeling (ATR) promotes atrial fibrillation (AF). Oxidant stress (OxS) occurs in atria of AF patients and antioxidants may be beneficial in AF. This study used a previously validated in vitro paced canine cardiomyocyte model to assess the potential role of OxS in ATR. Cultured canine atrial cardiomyocytes were paced at 1 or 3 Hz (P1, P3) for 24 hrs. I CaL was recorded with whole cell voltage clamp. Single cell superoxide production was assessed by dihydroethidium fluorescence (DHEF) imaging. ATR (3 Hz pacing x 24 hrs) decreased I CaL (Fig. A ) and induced OxS (Fig. B ). Short term induction of OxS (H 2 O 2 100 μM x 10 mins) increased I CaL (Fig. C ) and enhanced Ca 2+ loading (Indo-1 AM). 24-Hr H 2 O 2 100 μ M increased DHEF in P1 cells by 250%* (*P<0.05) and mimicked ATR, decreasing I CaL by 51%* (Fig. C ). H 2 O 2 -mediated DHEF changes were suppressed by inhibiting calmodulin (W7) or CaMKII (KN93). H 2 O 2 -induced I CaL suppression at 1 Hz was prevented by: decreasing Ca 2+ i loading by I CaL blockade (nimodipine) or Ca 2+ chelation (BAPTA-AM); W7 or KN93; antioxidants (2-MPG or N-acetylcysteine, NAC); or suppression of free radical generation via NADPH-oxidase (apocynin). 2-MPG, NAC, and apocynin prevented I CaL downregulation by 3-Hz pacing and W7, KN93 and apocynin abolished ATR-induced DHEF increases. H 2 O 2 mimics ATR by causing Ca 2+ i loading and CaMKII activation coupled to NADPH-oxidase stimulation. ATR-induced I CaL -downregulation is mediated in part by OxS generation. These findings provide insights into the pathways by which OxS contributes to ATR and present a mechanistic framework for understanding the effects of antioxidant interventions in AF.

Induction of reactive oxygen species and the potential role of NADPH oxidase in hyperhydricity of garlic plantlets in vitro

PROTOPLASMA ◽  
2016 ◽  
Vol 254 (1) ◽  
pp. 379-388 ◽  
Author(s):  
Jie Tian ◽  
Yaqi Cheng ◽  
Xiangyu Kong ◽  
Min Liu ◽  
Fangling Jiang ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Nadph Oxidase ◽  
Potential Role ◽  
Reactive Oxygen ◽  
Oxygen Species

scholarly journals Specificity of the HIV-1 Protease on Substrates Representing the Cleavage Site in the Proximal Zinc-Finger of HIV-1 Nucleocapsid Protein

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1092
Author(s):  
János András Mótyán ◽  
Márió Miczi ◽  
Stephen Oroszlan ◽  
József Tőzsér
Keyword(s):  
Amino Acid ◽  
Zinc Finger ◽  
Cleavage Site ◽  
Potential Role ◽  
Binding Mode ◽  
Interaction Energies ◽  
Vitro Assay ◽  
Hiv 1

To explore the sequence context-dependent nature of the human immunodeficiency virus type 1 (HIV-1) protease’s specificity and to provide a rationale for viral mutagenesis to study the potential role of the nucleocapsid (NC) processing in HIV-1 replication, synthetic oligopeptide substrates representing the wild-type and modified versions of the proximal cleavage site of HIV-1 NC were assayed as substrates of the HIV-1 protease (PR). The S1′ substrate binding site of HIV-1 PR was studied by an in vitro assay using KIVKCF↓NCGK decapeptides having amino acid substitutions of N17 residue of the cleavage site of the first zinc-finger domain, and in silico calculations were also performed to investigate amino acid preferences of S1′ site. Second site substitutions have also been designed to produce “revertant” substrates and convert a non-hydrolysable sequence (having glycine in place of N17) to a substrate. The specificity constants obtained for peptides containing non-charged P1′ substitutions correlated well with the residue volume, while the correlation with the calculated interaction energies showed the importance of hydrophobicity: interaction energies with polar residues were related to substantially lower specificity constants. Cleavable “revertants” showed one residue shift of cleavage position due to an alternative productive binding mode, and surprisingly, a double cleavage of a substrate was also observed. The results revealed the importance of alternative binding possibilities of substrates into the HIV-1 PR. The introduction of the “revertant” mutations into infectious virus clones may provide further insights into the potential role of NC processing in the early phase of the viral life-cycle.

scholarly journals High Expression of GSDMC Is Associated with Poor Survival in Kidney Clear Cell Cancer

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yun-Qian Cui ◽  
Fei Meng ◽  
Wen-Li Zhan ◽  
Zhou-Tong Dai ◽  
Xinghua Liao
Keyword(s):  
Potential Role ◽  
Clear Cell ◽  
Cell Cancer ◽  
Progression Free Survival ◽  
Renal Clear Cell Carcinoma ◽  
High Expression ◽  
Poor Survival ◽  
Free Survival

This study is aimed at exploring the potential role of GSDMC in kidney renal clear cell carcinoma (KIRC). We analyzed the expression of GSDMC in 33 types of cancers in TCGA database. The results showed that the expression of GSDMC was upregulated in most cancers. We found a significant association between high expression of GSDMC and shortened patient overall survival, progression-free survival, and disease-specific survival. In vitro experiments have shown that the expression of GSDMC was significantly elevated in KIRC cell lines. Moreover, decreased expression of GSDMC was significantly associated with decreased cell proliferation. In summary, we believe that this study provides valuable data supporting future clinical treatment.

scholarly journals Ozone Therapy as Adjuvant for Cancer Treatment: Is Further Research Warranted?

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Bernardino Clavo ◽  
Norberto Santana-Rodríguez ◽  
Pedro Llontop ◽  
Dominga Gutiérrez ◽  
Gerardo Suárez ◽  
...  
Keyword(s):  
Cancer Treatment ◽  
Immune Modulation ◽  
Animal Studies ◽  
Potential Role ◽  
Randomized Clinical Trials ◽  
Tumor Hypoxia ◽  
Tumor Resection ◽  
Ozone Therapy

Introduction. This article provides an overview of the potential use of ozone as an adjuvant during cancer treatment.Methods. We summarize the findings of the most relevant publications focused on this goal, and we include our related clinical experience.Results. Over several decades, prestigious journals have publishedin vitrostudies on the capacity of ozone to induce direct damage on tumor cells and, as well, to enhance the effects of radiotherapy and chemotherapy. Indirect effects have been demonstrated in animal models: immune modulation by ozone alone and sensitizing effect of radiotherapy by concurrent ozone administration. The effects of ozone in modifying hemoglobin dissociation curve, 2,3-diphosphoglycerate levels, locoregional blood flow, and tumor hypoxia provide additional support for potential beneficial effects during cancer treatment. Unfortunately, only a few clinical studies are available. Finally, we describe some works and our experience supporting the potential role of local ozone therapy in treating delayed healing after tumor resection, to avoid delays in commencing radiotherapy and chemotherapy.Conclusions.In vitroand animal studies, as well as isolated clinical reports, suggest the potential role of ozone as an adjuvant during radiotherapy and/or chemotherapy. However, further research, such as randomized clinical trials, is required to demonstrate its potential usefulness as an adjuvant therapeutic tool.

scholarly journals Potential Role of the Chemokine Macrophage Inflammatory Protein 1α in Human and Experimental Schistosomiasis

2005 ◽  
Vol 73 (4) ◽  
pp. 2515-2523 ◽  
Author(s):  
Adriano L. S. Souza ◽  
Ester Roffê ◽  
Vanessa Pinho ◽  
Danielle G. Souza ◽  
Adriana F. Silva ◽  
...  
Keyword(s):  
Potential Role ◽  
Severe Disease ◽  
Experimental Studies ◽  
Interleukin 4 ◽  
Enzyme Linked Immunosorbent Assay ◽  
Inflammatory Protein ◽  
Macrophage Inflammatory Protein ◽  
Deficient Mice

ABSTRACT In human schistosomiasis, the concentrations of the chemokine macrophage inflammatory protein 1α (MIP-1α/CCL3) is greater in the plasma of patients with clinical hepatosplenic disease. The objective of the present study was to confirm the ability of CCL3 to detect severe disease in patients classified by ultrasonography (US) and to evaluate the potential role of CCL3 in Schistosoma mansoni-infected mice. CCL3 was measured by enzyme-linked immunosorbent assay in the plasma of S. mansoni-infected patients. CCL3-deficient mice were infected with 25 cercariae, and various inflammatory and infectious indices were evaluated. The concentration of CCL3 was higher in the plasma of S. mansoni-infected than noninfected patients. Moreover, CCL3 was greater in those with US-defined hepatosplenic than with the intestinal form of the disease. In CCL3-deficient mice, the size of the granuloma and the liver eosinophil peroxidase activity and collagen content were diminished compared to wild-type mice. In CCL3-deficient mice, the worm burden after 14 weeks of infection, but not after 9 weeks, was consistently smaller. The in vitro response of mesenteric lymph node cells to antigen stimulation was characterized by lower levels of interleukin-4 (IL-4) and IL-10. CCL3 is a marker of disease severity in infected humans, and experimental studies in mice suggest that CCL3 may be a causative factor in the development of severe schistosomiasis.

scholarly journals Role for the Related Poly(ADP-Ribose) Polymerases Tankyrase 1 and 2 at Human Telomeres

2002 ◽  
Vol 22 (1) ◽  
pp. 332-342 ◽  
Author(s):  
Brandoch D. Cook ◽  
Jasmin N. Dynek ◽  
William Chang ◽  
Grigoriy Shostak ◽  
Susan Smith
Keyword(s):  
Potential Role ◽  
Telomere Maintenance ◽  
Telomeric Dna ◽  
Continuous Growth ◽  
Telomere Elongation ◽  
Bona Fide ◽  
Tankyrase 1 ◽  
Growth Of Tumor

ABSTRACT Telomere maintenance is essential for the continuous growth of tumor cells. In most human tumors telomeres are maintained by telomerase, a specialized reverse transcriptase. Tankyrase 1, a human telomeric poly(ADP-ribose) polymerase (PARP), positively regulates telomere length through its interaction with TRF1, a telomeric DNA-binding protein. Tankyrase 1 ADP-ribosylates TRF1, inhibiting its binding to telomeric DNA. Overexpression of tankyrase 1 in the nucleus promotes telomere elongation, suggesting that tankyrase 1 regulates access of telomerase to the telomeric complex. The recent identification of a closely related homolog of tankyrase 1, tankyrase 2, opens the possibility for a second PARP at telomeres. We therefore sought to establish the role of tankyrase 1 at telomeres and to determine if tankyrase 2 might have a telomeric function. We show that endogenous tankyrase 1 is a component of the human telomeric complex. We demonstrate that telomere elongation by tankyrase 1 requires the catalytic activity of the PARP domain and does not occur in telomerase-negative primary human cells. To investigate a potential role for tankyrase 2 at telomeres, recombinant tankyrase 2 was subjected to an in vitro PARP assay. Tankyrase 2 poly(ADP-ribosyl)ated itself and TRF1. Overexpression of tankyrase 2 in the nucleus released endogenous TRF1 from telomeres. These findings establish tankyrase 2 as a bona fide PARP, with itself and TRF1 as acceptors of ADP-ribosylation, and suggest the possibility of a role for tankyrase 2 at telomeres.

NAD(P)H oxidase-generated superoxide anion accounts for reduced control of myocardial O2 consumption by NO in old Fischer 344 rats

2003 ◽  
Vol 285 (3) ◽  
pp. H1015-H1022 ◽  
Author(s):  
Alexandra Adler ◽  
Eric Messina ◽  
Ben Sherman ◽  
Zipping Wang ◽  
Harer Huang ◽  
...  
Keyword(s):  
Oxidant Stress ◽  
Heart Weight ◽  
Fischer 344 Rats ◽  
No Donor ◽  
Fischer 344 ◽  
Old Rats ◽  
Fischer Rats ◽  
Enos Protein

We investigated the role of nitric oxide (NO) in the control of myocardial O2 consumption in Fischer 344 rats. In Fischer rats at 4, 14, and 23 mo of age, we examined cardiac function using echocardiography, the regulation of cardiac O2 consumption in vitro, endothelial NO synthase (eNOS) protein levels, and potential mechanisms that regulate superoxide. Aging was associated with a reduced ejection fraction [from 75 ± 2%at4moto66 ± 3% ( P < 0.05) at 23 mo] and an increased cardiac diastolic volume [from 0.60 ± 0.04 to 1.00 ± 0.10 ml ( P < 0.01)] and heart weight (from 0.70 ± 0.02 to 0.90 ± 0.02 g). The NO-mediated control of cardiac O2 consumption by bradykinin or enalaprilat was not different between 4 mo (36 ± 2 or 34 ± 3%) and 14 mo (29 ± 1 or 25 ± 3%) but markedly ( P < 0.05) reduced in 23-mo-old Fischer rats (15 ± 3 or 7 ± 2%). The response to the NO donor S-nitroso- N-acetyl penicillamine was not different across groups (35%, 35%, and 44%). Interestingly, the eNOS protein level was not different at 4, 14, and 23 mo. The addition of tempol (1 mmol/l) to the tissue bath eliminated the depression in the control of cardiac O2 consumption by bradykinin (25 ± 3%) or enalaprilat (28 ± 3%) in 23-mo-old Fischer rats. We next examined the levels of enzymes involved in the production and breakdown of superoxide. The expression of Mn SOD, Cu/Zn SOD, extracellular SOD, and p67phox, however, did not differ between 4- and 23-mo-old rats. Importantly, there was a marked increase in gp91phox, and apocynin restored the defect in NO-dependent control of cardiac O2 consumption at 23 mo to that seen in 4-mo-old rats, identifying the role of NADPH oxidase. Thus increased biological activity of superoxide and not decreases in the enzyme that produces NO are responsible for the altered control of cardiac O2 consumption by NO in 23-mo-old Fischer rats. Increased oxidant stress in aging, by decreasing NO bioavailability, may contribute not only to changes in myocardial function but also to altered regulation of vascular tone and the progression of cardiac or vascular disease.

scholarly journals Malaria and red cell genetic defects

Blood ◽  
1989 ◽  
Vol 74 (4) ◽  
pp. 1213-1221 ◽  
Author(s):  
RL Nagel ◽  
EF Jr Roth
Keyword(s):  
Culture System ◽  
Potential Role ◽  
Dna Analysis ◽  
Red Cell ◽  
Metabolic Products ◽  
Recombinant Technology ◽  
Host Parasite ◽  
Made In

Abstract The study of inherited RBC resistance to malaria has increased our knowledge of the biochemistry and physiology of the host-parasite interaction and suggested potential sites for therapeutic intervention. Discovery by Jensen and Trager of the in vitro culture system for P falciparum has facilitated research in this area. Known RBC defects may affect invasion, growth, or merozoite liberation (Fig 1). Significant advances made in understanding mechanisms underlying protection against malaria should not obscure the fact that the data are far from complete. More knowledge is needed about the influence of the erythrocyte cytoskeleton on invasion and growth of parasites as well as the potential role of phospholipids, erythrocyte enzymes other than G6PD, or other metabolic products. Application of DNA analysis and recombinant technology may have an increasing impact on study of the interaction of RBC defects with malarial parasites.

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