Mechanisms of Oxygen Activation and Reactive Oxygen Species Detoxification

Cadenas, Enrique

doi:10.1007/978-1-4615-9689-9_1

Cited by 58 publications

(53 citation statements)

References 225 publications

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“…Catalase is concentrated in the peroxisome, where it scavenges H20, that is generated in the photorespiratory cycle. Cytosolic and mitochondrial isoforms of SOD, APX, GR, and catalase also exist, where they may function to scavenge ROS that is generated by mitochondrial electron transport (Cadenas, 1995), autoxidation of sugars (Fridovich, 1995), or plasma membrane-linked redox reactions (Rubinstein and Luster, 1993 Few studies have directly addressed whether growth at high irradiance induces an increase in cellular antioxidant systems due to higher rates of O, photoreduction. Although short-term exposure of plants (minutes to hours) to high PFDs at normal temperatures (18-25°C) appears to have little effect on foliar antioxidant levels (Foyer et al, 1989;Mishra et al, 1993), longer-term acclimation to high PFDs appears to have a positive effect on these systems.…”

mentioning

confidence: 99%

Acclimation of Foliar Antioxidant Systems to Growth Irradiance in Three Broad-Leaved Evergreen Species

1996

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Colorado 80309-0334 l h e protective role of leaf antioxidant systems i n the mechanism of plant acclimation to growth irradiance was studied in Vinca major, Schefflera arboricola, and Mahonia repens, which were grown for several months at 20, 100, and 1200 pmol photons m-* s-'. As growth irradiance increased, several constituents of the "Mehler-peroxidase" pathway also increased: superoxide dismutase, ascorbate peroxidase, glutathione reductase, ascorbate, and glutathione. This occurred concomitantly with increases i n the xanthophyll cycle pool size and in the rate of nonphotochemical energy dissipation under steady-state conditions. There was no evidence for photosystem II overreduction in plants grown at high irradiance, although the reduction state of the stromal NADP pool, estimated from measurements of NADP-malate dehydrogenase activity, was greater than 60% in V. major and S. arboricola. Ascorbate, which removes reactive O, species generated by O, photoreduction in the chloroplast and serves as a reductant for the conversion of the xanthophyll cycle pigments to the de-epoxidized forms A plus 2, generally exhibited the most dramatic increases in response to growth irradiance. We conclude from these results that O, photoreduction occurs at higher rates i n leaves acclimated to high irradiance, despite increases in xanthophyll cycle-dependent energy dissipation, and that increases in leaf antioxidants protect against this potential oxidative stress.Plants acclimated to high irradiance use various mechanisms to protect the photosynthetic apparatus against the deleterious effects of excess light absorption. Much attention has been focused on elucidating the role of the xanthophyll cycle in the dissipation of excess excitation energy in the light-harvesting antennae . The associated increases in the xanthophyll cycle pool size, V plus A plus Z, and the capacity for nonphotochemical energy dissipation, NPQ, is a well-characterized and apparently fundamental acclimatory response to high PFDs (Bjorkman and Demmig-Adams, 1994; DemmigAdams and Adams, 1994). Xanthophyll cycle-dependent energy dissipation lowers the photon efficiency of PSII, thus providing a mechanism to balance the synthesis of ATP and NADPH with the rate at which these metabolites can be utilized in photosynthesis (Foyer, 1993 , 1995) or serve a regulatory role by augmenting the transthylakoid proton gradient (Schreiber and Neubauer, 1990). Although the magnitude of O,-dependent flux in vivo remains controversial, direct measurements using MS suggest that in C, plants up to 25% of the total noncyclic electron transport is consumed by this process at light saturation (Canvin et al., 1980;Badger, 1985;Osmond and Grace, 1995). Protection against the possible toxicity of ROS is afforded by an integrated system of enzymatic and nonenzymatic antioxidants that are concentrated in the chloroplast (Asada, 1994). The superoxide anion, the initial product of photosynthetic O, reduction, is either dismuted by SOD or reduced by ascorbate to H,O,, which is t...

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mentioning

confidence: 99%

Acclimation of Foliar Antioxidant Systems to Growth Irradiance in Three Broad-Leaved Evergreen Species

1996

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“…Although being a common component of most cellular membranes, CoQ10's most prominent role is to facilitate the production of ATP by participating in redox reactions within the electron transport chain in the mitochondria. 8 Within the electron transport chain, CoQ10 accepts electrons from complexes I and II and transports them to complex III. At this point, it is ready to be reduced by complexes I and II again (Figure 2).…”

Section: Sharma Et Almentioning

confidence: 99%

Coenzyme Q10 and Heart Failure

Sharma

Fonarow

Butler

et al. 2016

Circ: Heart Failure

120

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Abstract-Heart failure (HF) with either preserved or reduced ejection fraction is associated with increased morbidity and mortality. Evidence-based therapies are often limited by tolerability, hypotension, electrolyte disturbances, and renal dysfunction. Coenzyme Q10 (CoQ10) may represent a safe therapeutic option for patients with HF. CoQ10 is a highly lipophilic molecule with a chemical structure similar to vitamin K. Although being a common component of cellular membranes, CoQ10's most prominent role is to facilitate the production of adenosine triphosphate in the mitochondria by participating in redox reactions within the electron transport chain. Numerous trials during the past 30 years examining CoQ10 in patients with HF have been limited by small numbers and lack of contemporary HF therapies. The recent publication of the Q-SYMBIO randomized controlled trial demonstrated a reduction in major adverse cardiovascular events with CoQ10 supplementation in a contemporary HF population. Although having limitations, this study has renewed interest in evaluating CoQ10 supplementation in patients with HF. Current literature suggests that CoQ10 is relatively safe with few drug interactions and side effects. Furthermore, it is already widely available as an over-the-counter supplement. These findings warrant future adequately powered randomized controlled trials of CoQ10 supplementation in patients with HF. This state-of-the-art review summarizes the literature about the mechanisms, clinical data, and safety profile of CoQ10 supplementation in patients with HF. (Circ Heart Fail. 2016;9:e002639.

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“…Testis torsiyonu iskemik hasar, detorsiyon ise reperfüzyon hasarı oluşturarak dokuda yapısal ve biyokimyasal bir takım değişikliklerin ortaya çıkmasına neden olur. Çalışmalar dokudaki iskemi-reperfüzyon hasarından serbest oksijen radikallerinin sorumlu olduğunu göstermiştir [2]. Serbest oksijen radikalleri (SOR) organizmada dokunun yapı elemanlarını bozarak zararlı etkilere yol açabilir.…”

Section: Introductionunclassified

Deneysel testiküler torsiyon modelinde N-asetilsistein doku hasarını önlemede rol oynayabilir mi?

Aydiner¹,

Pul²,

İnan³

et al. 2012

CMJ

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Amaç. Testis torsiyonu, iskemi reperfüzyon hasarı formunda önemli bir akut skrotum nedenidir. Başarılı ve erken bir detorsiyon yöntemi ile morbidite azaltılabilir. Bu çalışmada deneysel tek taraflı testis torsiyonu ve detorsiyonu modelinde N-asetilsistein'in her iki testise olan etkisinin araştırılması amaçlandı. Yöntem. Çalışmada 32 adet prepubertal erkek Wistar albino sıçan kullanıldı. Sıçanlar malondialdehid düzeyi ve histopatolojik hasar araştırılmak üzere kontrol, torsiyon, detorsiyon ve detorsiyon/N-asetilsistein gruplarına ayrıldı. Kontrol grubunda yer alan deneklere torsiyon işlemi uygulanmadan testisleri alındı. Diğer gruplardaki deneklerin sağ testislerine dörder saatlik torsiyon işlemi uygulandı. Detorsiyon/N-asetilsistein grubunda detorsiyondan 15 dk önce intravenöz N-asetilsistein verildi. Detorsiyon ve detorsiyon/Nasetilsistein gruplarında reperfüzyon sonrası dört saat daha beklendi. Deney sonunda tüm gruplarda her iki testis de çıkarılarak malondialdehid düzeyleri çalışıldı ve histopatolojik olarak değerlendirildi. Malondialdehid sonuçları Kruskal-Wallis varyans analizi ve Mann Whitney U testleriyle değerlendirildi. Farkın p için 0,05'den küçük olduğu değerler anlamlı kabul edildi. Bulgular. Her iki testise ait malondialdehid düzeyleri tüm gruplarda kontrol grubuna göre daha yüksek olarak bulundu (p<0,05). Detorsiyon/N-asetilsistein grubu ile detorsiyon grubu arasında her iki testis dokusuna ait malondialdehid düzeyleri bakımından anlamlı fark saptanmadı (p>0,05). İşlem sonrasında kontrol grubu dışındaki tüm grupların torsiyone testislerinde interstisyel hemoraji ile seminifer tübül yapılarında düzensizlik gözlendi. Karşı tarafta interstisyel ödem ve bazı olgularda germ hücrelerinin dökülmesi dışında normal histoloji izlendi. Sonuç. Sonuç olarak oluşturduğumuz deneysel testis torsiyonu modelinde detorsiyondan önce intravenöz N-asetilsistein uygulamasının her iki testiste malondialdehid düzeyleri ve histopatolojik hasar üzerinde bir etkisinin olmadığı saptandı. Anahtar sözcükler: Testis torsiyonu, iskemi-reperfüzyon hasarı, N-asetilsistein AbstractAim. Testicular torsion, which is in the form of ischemia-reperfusion, is an important cause of acute scrotum. The morbidity could be decreased by an early and successful detorsion procedure. The aim of this study was to determine the effects of N-acetylcysteine on both testes in experimental rat model of unilateral testicular torsion and detorsion. Method. In this study, 32 prepubertal male albino Wistar rats were used. The rats were divided into four groups as control, torsion, detorsion and detorsion/N-acetylcysteine in order to determine the malondialdehyde level and histopathological damage. Rats in the control group were killed after the testes were removed without torsion. Right testes of the rats underwent four hours of torsion in other groups. Nacetylcysteine was injected intravenously 15 min before the detorsion in detorsion/Nacetylcysteine group. Reperfusion was continued for four hours after detorsion in detorsion and detorsion/N-acetylcystein...

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Mechanisms of Oxygen Activation and Reactive Oxygen Species Detoxification

Cited by 58 publications

References 225 publications

Acclimation of Foliar Antioxidant Systems to Growth Irradiance in Three Broad-Leaved Evergreen Species

Acclimation of Foliar Antioxidant Systems to Growth Irradiance in Three Broad-Leaved Evergreen Species

Coenzyme Q10 and Heart Failure

Deneysel testiküler torsiyon modelinde N-asetilsistein doku hasarını önlemede rol oynayabilir mi?

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