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Caibin Sheng, Heyu Chen,
Ban Wang,
Tengyuan Liu,
Yunyi Hong,
Jiaxiang Shao,
Xin He,
Yingxin Ma,
Hui Nie,
Na Liu,
Weiliang Xia,
Weihai Ying
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ABSTRACT: Synchrotron radiation (SR) X-ray has great potential for its applications in medical imaging and cancer treatment. In order to apply SR X-ray in clinical settings, it is necessary to elucidate the mechanisms underlying the damaging effects of SR X-ray on normal tissues, and to search for the strategies to reduce the detrimental effects of SR X-ray on normal tissues. However, so far there has been little information on these topics. In this study we used the testes of rats as a model to characterize SR X-ray-induced tissue damage, and to test our hypothesis that NAD(+) administration can prevent SR X-ray-induced injury of the testes. We first determined the effects of SR X-ray at the doses of 0, 0.5, 1.3, 4 and 40 Gy on the biochemical and structural properties of the testes one day after SR X-ray exposures. We found that 40 Gy of SR X-ray induced a massive increase in double-strand DNA damage, as assessed by both immunostaining and Western blot of phosphorylated H2AX levels, which was significantly decreased by intraperitoneally (i.p.) administered NAD(+) at doses of 125 and 625 mg/kg. Forty Gy of SR X-ray can also induce marked increases in abnormal cell nuclei as well as significant decreases in the cell layers of the seminiferous tubules one day after SR X-ray exposures, which were also ameliorated by the NAD(+) administration. In summary, our study has shown that SR X-ray can produce both molecular and structural alterations of the testes, which can be significantly attenuated by NAD(+) administration. These results have provided not only the first evidence that SR X-ray-induced tissue damage can be ameliorated by certain approaches, but also a valuable basis for elucidating the mechanisms underlying SR X-ray-induced tissue injury.
International Journal of Physiology, Pathophysiology and Pharmacology 01/2012; 4(1):1-9.
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Yingxin Ma,
Hui Nie,
Caibin Sheng, Heyu Chen,
Ban Wang,
Tengyuan Liu,
Jiaxiang Shao,
Xin He,
Tingting Zhang,
Chaobo Zheng,
Weiliang Xia,
Weihai Ying
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ABSTRACT: Synchrotron radiation (SR) X-ray has characteristic properties such as coherence and high photon flux, which has excellent potential for its applications in medical imaging and cancer treatment. However, there is little information regarding the mechanisms underlying the damaging effects of SR X-ray on biological tissues. Oxidative stress plays an important role in the tissue damage induced by conventional X-ray, while the role of oxidative stress in the tissue injury induced by SR X-ray remains unknown. In this study we used the male gonads of rats as a model to study the roles of oxidative stress in SR X-ray-induced tissue damage. Exposures of the testes to SR X-ray at various radiation doses did not significantly increase the lipid peroxidation of the tissues, assessed at one day after the irradiation. No significant decreases in the levels of GSH or total antioxidation capacity were found in the SR X-ray-irradiated testes. However, the SR X-ray at 40 Gy induced a marked increase in phosphorylated H2AX - a marker of double-strand DNA damage, which was significantly decreased by the antioxidant N-acetyl cysteine (NAC). NAC also attenuated the SR X-ray-induced decreases in the cell layer number of seminiferous tubules. Collectively, our observations have provided the first characterization of SR X-ray-induced oxidative damage of biological tissues: SR X-ray at high doses can induce DNA damage and certain tissue damage during the acute phase of the irradiation, at least partially by generating oxidative stress. However, SR X-ray of various radiation doses did not increase lipid peroxidation.
International Journal of Physiology, Pathophysiology and Pharmacology 01/2012; 4(2):108-14.
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ABSTRACT: Numerous studies have indicated that four interacting factors, including oxidative stress, mitochondrial alterations, calcium dyshomeostasis and inflammation, play crucial pathological roles in multiple major neurological diseases, including stroke, Alzheimer's disease (AD) and Parkinson's disease (PD). Increasing evidence has also indicated that NAD(+) plays important roles in not only mitochondrial functions and energy metabolism, but also calcium homeostasis and inflammation. The key NAD(+)-consuming enzyme--poly(ADP-ribose) polymerase-1 (PARP-1) and sirtuins--have also been shown to play important roles in cell death and aging, which are two key factors in the pathology of multiple major age-dependent neurological diseases: PARP-1 plays critical roles in both inflammation and oxidative stress-induced cell death; and sirtuins also mediate the process of aging, cell death and inflammation. Thus, it is conceivable that increasing evidence has suggested that NAD(+) metabolism and NAD(+)-dependent enzymes are promising targets for treating a number of neurological illnesses. For examples, the key NAD(+)-dependent enzymes SIRT1 and SIRT2 have been indicated to strongly affect the pathological changes of PD and AD; PARP-1 inhibition can profoundly reduce the brain injury in the animal models of multiple neurological diseases; and administration of either NAD(+) or nicotinamide can also decrease ischemic brain damage. Future studies are necessary to further investigate the roles of NAD+ metabolism and NAD⁺-dependent enzymes in neurological diseases, which may expose novel targets for treating the debilitating illnesses.
Current drug targets 12/2011; 13(2):222-9. · 3.93 Impact Factor
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ABSTRACT: Reduced nicotinamide adenine dinucleotide (NADH) plays key roles in energy metabolism and mitochondrial functions. However, there has been little information regarding the effect of NADH on cell survival. In this study we determined the effect of NADH treatment on the survival of glioma cells. We found that treatment of C6 glioma cells with as low as 1 μM NADH for 24 hrs significantly decreased the survival of these cells, and that treatment of the cells with 1000 μM NADH for 4 days decreased the survival of the cells by nearly 90%. This effect of NADH on glioma cells appears to be mediated by oxidative stress, as indicated by our findings that NADH treatment induced an increase in intracellular reactive oxygen species, and that two antioxidants, N-acetyl cysteine and Trolox, significantly attenuated the effect of NADH. We also found that NADH treatment induced an increase in poly(ADP-ribose) polymerase (PARP) activity, and that PARP inhibitors decreased the effect of NADH on the survival of glioma cells. These observations suggest that NADH reduces the cell survival at least partially by activating PARP. Collectively, our studies demonstrated a novel biological property of NADH - NADH decreases glioma cell survival by increasing oxidative stress and PARP activation. These results also suggest that NADH may have therapeutic potential for treating gliomas.
International Journal of Physiology, Pathophysiology and Pharmacology 01/2011; 3(1):21-8.
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ABSTRACT: Sirtuin 2 (SIRT2), a tubulin deacetylase, is a sirtuin family protein. SIRT2 inhibitors have been shown to decrease the cell death in cellular and Drosophila models of Parkinson's disease. However, SIRT2 decreases may also compromise cellular antioxidation capacity. Our current study found that silencing of SIRT2 led to a decrease in the intracellular ATP level of PC12 cells. We also found that AGK2, a selective SIRT2 inhibitor, can exacerbate H2O2-induced decreases in the intracellular ATP level of these cells. Our study further indicated that the reduction in SIRT2 level significantly increased necrosis of PC12 cells without affecting autophagy of the cells. These results suggest that SIRT2 is a key mediator of energy metabolism and basal survival of PC12 cells.
International Journal of Physiology, Pathophysiology and Pharmacology 01/2011; 3(1):65-70.
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ABSTRACT: NADPH (nicotinamide adenine dinucleotide phosphate, reduced form) plays pivotal roles in antioxidation and reductive biosynthesis. However, the effect of NADPH treatment on cell survival is unknown. In this study, we determined the effect of NADPH treatment on the survival of glioma cells. Treatment of C6 glioma cells with as low as 1 μM NADPH for 24 hrs induced a significant decrease in the survival of the glioma cells, while NADPH treatment had no effect on the survival of primary astrocyte cultures. We also found that NADPH treatment increased intracellular oxidative stress. Three antioxidants and the NADPH oxidase inhibitor, apocynin, attenuated the effect of NADPH. Poly(ADP-ribose) polymerase (PARP) activation appears to be a downstream effector of the oxidative stress, since PARP inhibitors reduced the effect of NADPH. Calcium chelator, BAPTA-AM, also attenuated the effect of NADPH. Collectively, these data indicate a novel property of NADPH: NADPH decreases glioma cell survival by inducing the NADPH oxidase-dependent increase in oxidative stress and by PARP activation. These results also suggest a potential therapeutic effect of NADPH on gliomas.
Frontiers in bioscience (Elite edition) 01/2011; 3:1221-8.
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ABSTRACT: NAD+ plays important roles in various biological processes. It has been shown that NAD+ treatment can decrease genotoxic agent-induced death of primary neuronal and astrocyte cultures, and NAD+ administration can reduce ischemic brain damage. However, the effects of NAD+ treatment on tumor cell survival are unknown. In this study we found that treatment of NAD+ at concentrations from 10 micromolar to 1 mM can significantly decrease the survival of various types of tumor cells such as C6 glioma cells. In contrast, NAD+ treatment did not impair the survival of primary astrocyte cultures. Our study has also indicated that oxidative stress mediates the effects of NAD+ on the survival of tumor cells, and P2X7 receptors and altered calcium homeostasis are involved in the effects of NAD+ on the cell survival. Collectively, our study has provided the first evidence that NAD+ treatment can decrease the survival of tumor cells by such mechanisms as inducing oxidative stress. Because NAD+ treatment can selectively decrease the survival of tumor cells, NAD+ may become a novel agent for treating cancer.
Frontiers in bioscience (Elite edition) 01/2011; 3:434-41.
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ABSTRACT: Synchrotron radiation (SR) X-ray has great potential for its applications in both diagnosis and treatment of diseases, due to its characteristic properties including coherence, collimation, monochromaticity, and exceptional brightness. Great advances have been made regarding potential medical applications of SR X-ray in recent years, particularly with the development of the third generation of SR light sources. However, multiple studies have also suggested damaging effects of SR X-ray on biological samples ranging from protein crystals to cells and biological tissues. It has become increasingly important to conduct comprehensive studies on two closely related topics regarding SR X-ray in medical applications: The safety issues regarding the medical applications of SR X-ray and the fundamental mechanisms underlying the interactions between SR X-ray and biological tissues. In this article, we attempted to provide an overview of the literatures regarding these two increasingly significant topics. We also proposed our hypothesis that there are significant differences between the biological tissue-damaging mechanisms of SR X-ray and those of normal X-ray, due to the characteristic properties of SR X-ray such as high dose rate. Future studies are warranted to test this hypothesis, which may profoundly improve our understanding regarding the fundamental mechanisms underlying the interactions between light and matter. These studies would also constitute an essential basis for establishing the safety standard for the medical applications of SR X-ray.
International Journal of Physiology, Pathophysiology and Pharmacology 01/2011; 3(4):243-8.
