The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform
Juan Hidalgo - One of the best experts on this subject based on the ideXlab platform.
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Metallothionein prevents neurodegeneration and central nervous system cell death after treatment with gliotoxin 6-Aminonicotinamide.
Journal of neuroscience research, 2004Co-Authors: Milena Penkowa, Albert Quintana, Javier Carrasco, Mercedes Giralt, Amalia Molinero, Juan HidalgoAbstract:Transgenic expression of interleukin-6 (IL-6) in the CNS under the control of the glial fibrillary acidic protein (GFAP) gene promoter (GFAP-IL6 mice) induces significant inflammation and neurodegeneration but also affords neuroprotection against acute traumatic brain injury. This neuroprotection is likely mediated by the IL-6-induced protective factors metallothioneins-I and -II (MT-I+II). Here we evaluate the neuroprotective roles of IL-6 vs. MT-I+II during 6-Aminonicotinamide (6-AN)-induced neurotoxicity, by using GFAP-IL6 mice and transgenic mice overexpressing MT-I (TgMT) as well as GFAP-IL6 mice crossed with TgMT mice (GFAP-IL6 x TgMT). 6-AN caused acute damage of brainstem gray matter areas identified by necrosis of astrocytes, followed by inflammatory responses. After 6-AN-induced toxicity, secondary damage was observed, consisting of oxidative stress, neurodegeneration, and apoptotic cell death. We hereby show that the primary injury caused by 6-AN was comparable in wild-type and GFAP-IL6 mice, but MT-I overexpression could significantly protect the brain tissue. As expected, GFAP-IL6 mice showed increased CNS inflammation with more gliosis, macrophages, and lymphocytes, including increased cytokine expression, relative to the other mice. However, GFAP-IL6 mice showed reduced oxidative stress (judged from nitrotyrosine, malondialdehyde, and 8-oxoguanine stainings), neurodegeneration (accumulation of neurofibrillary tangles), and apoptosis (determined from TUNEL and caspase-3). MT-I+II expression was significantly higher in GFAP-IL6 mice than in wild types, which may contribute to the IL-6-induced neuroprotection. In support of this, overexpression of MT-I in GFAP-IL6 x TgMT as well as TgMT mice protected the brainstem tissue significantly from 6-AN-induced toxicity and secondary brain tissue damage. Overall, the results demonstrate that brain MT-I+II proteins are fundamental neuroprotective factors, which in the future may become therapeutic agents.
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astrocyte targeted expression of interleukin 6 protects the central nervous system during neuroglial degeneration induced by 6 Aminonicotinamide
Journal of Neuroscience Research, 2003Co-Authors: Milena Penkowa, Albert Quintana, Mercedes Giralt, Amalia Molinero, Jordi Camats, Hanne Hadberg, Santiago Rojas, Iain L Campbell, Juan HidalgoAbstract:6-Aminonicotinamide (6-AN) is a niacin antagonist, which leads to degeneration of gray matter astrocytes mainly in the brainstem. We have examined the role of interleukin-6 (IL-6) in this degenerative process by using transgenic mice with astrocyte-targeted IL-6 expression (GFAP-IL6 mice). This study demonstrates that transgenic IL-6 expression significantly increases the 6-AN-induced inflammatory response of reactive astrocytes, microglia/macrophages, and lymphocytes in the brainstem. Also, IL-6 induced significant increases in proinflammatory cytokines IL-1, IL-12, and tumor necrosis factor-alpha as well as growth factors basic fibroblast growth factor (bFGF), transforming growth factor-beta, neurotrophin-3, angiopoietin, vascular endothelial growth factor, and the receptor for bFGF. In accordance, angiogenesis was increased in GFAP-IL6 mice relative to controls after 6-AN. Moreover, oxidative stress and apoptotic cell death were significantly reduced by transgenic IL-6 expression. IL-6 is also a major inducer in the CNS of metallothionein I and II (MT-I+II), which were significantly increased in the GFAP-IL6 mice. MT-I+II are antioxidants and neuroregenerative factors in the CNS, so increased MT-I+II levels in GFAP-IL6 mice could contribute to the reduction of oxidative stress and cell death in these mice.
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retracted m csf deficiency leads to reduced metallothioneins i and ii expression and increased tissue damage in the brain stem after 6 Aminonicotinamide treatment
Experimental Neurology, 2002Co-Authors: Milena Penkowa, Javier Carrasco, Christian Bjorn Poulsen, Juan HidalgoAbstract:6-Aminonicotinamide (6-AN) is a niacin antagonist, which leads to degeneration of gray-matter astrocytes followed by a vigorous inflammatory response. Macrophage colony stimulating factor (M-CSF) is important during inflammation, and in order to further clarify the roles for M-CSF in neurodegeneration and brain cell death, we have examined the effect of 6-AN on osteopetrotic mice with genetic M-CSF deficiency (op/op mice). The 6-AN-induced degeneration of gray-matter areas was comparable in control and op/op mice, but the numbers of reactive astrocytes, macrophages, and lymphocytes in the damaged areas were significantly decreased in op/op mice relative to controls. The levels of oxidative stress (as determined by using immunoreactivity for inducible nitric oxide synthase, nitrotyrosine, and malondialdehyde) and apoptotic cell death (as determined by using TUNEL and immunoreactivity for caspases and cytochrome c) were significantly increased in 6-AN-injected op/op mice relative to controls. From a number of antioxidant factors assayed, only metallothioneins I and II (MT-I+II) were decreased in op/op mice in comparison to controls. Thus, the present results indicate that M-CSF is an important growth factor for coping with 6-AN-induced central nervous system damage and suggest that MT-I+II are likely to have a significant role.
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metallothionein 1 2 protect the cns during neuroglial degeneration induced by 6 Aminonicotinamide
The Journal of Comparative Neurology, 2002Co-Authors: Milena Penkowa, Mercedes Giralt, Jordi Camats, Juan HidalgoAbstract:6-Aminonicotinamide (6-AN) is a niacin antagonist, which leads to degeneration of gray matter astrocytes. Metallothionein 1+2 (MT-1+2) are neuroprotective factors in the central nervous system (CNS), and to determine the roles for MT after 6-AN, we have examined transgenic mice overexpressing MT-1 (TgMTI* mice) after an i.p. injection with 6-AN. In control mice injected with 6-AN, astrocytes in specific gray matter areas of the brainstem showed degeneration. Reactive astrocytes surrounded the degenerated areas, which were heavily infiltrated by macrophages and T lymphocytes. MT-1+2 expression was significantly decreased in the damaged brainstem areas, but it increased in reactive astrocytes surrounding these areas and also in infiltrating macrophages. The levels of oxidative stress, as determined by immunoreactivity for inducible nitric-oxide synthase (iNOS), malondialdehyde (MDA), and nitrotyrosine (NITT), and the number of terminal deoxynucleotidyl transferase [TdT]-mediated deoxyuridine triphosphate [dUTP]-digoxigenin nick end labeling–positive (TUNEL+), caspase-3+ apoptotic cells were significantly increased in the brainstem of normal mice after 6-AN. In the TgMTI* mice, the 6-AN–induced tissue damage was decreased in comparison to control mice, and they showed significantly reduced numbers of recruited macrophages and T lymphocytes, and a drastic reduction of oxidative stress and apoptotic cell death. In addition, the accompanying reactive astrogliosis was increased in the transgenic mice. To further study the potential protective role of MT, we administered intraperitoneally Zn-MT-2 to 6-AN–injected normal mice and found essentially the same results as those obtained in TgMTI* mice. Thus, we hereby report that endogenous MT-1 overexpression and exogenous MT-2 treatment have significant neuroprotective roles during CNS pathological conditions. J. Comp. Neurol. 444:174–189, 2002. © 2002 Wiley-Liss, Inc.
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increased astrocytic expression of metallothioneins i ii in brainstem of adult rats treated with 6 Aminonicotinamide
Brain Research, 1997Co-Authors: Milena Penkowa, Juan Hidalgo, Torben MoosAbstract:Abstract The cerebral distribution of metallothioneins I and II (MT-I+II) was studied in adult rats subjected to i.p injection with the gliotoxin 6-Aminonicotinamide (6-AN). Grey matter regions of the brainstem heralded numerous OX-42-positive macrophages and microglia, indicating that 6-AN primarily caused damage to this part of the brain. In the grey matter regions infiltrated with OX-42-positive cells, astrocytes identified by anti-GFAP and MT-I+II antibodies were almost absent. By contrast, in the peripheral zone of the lesioned regions numerous reactive GFAP- and MT-I+II-positive astrocytes were observed. The blood–brain barrier (BBB) to serum albumin was compromised in the entire brainstem. The astrocytic expression of MT-I+II could reflect the brains needs to scavenge metal ions released from either damaged cells or plasma proteins entering the brain due to the injured BBB, as well as it could reflect the potential antioxidant function of MT-I+II.
Milena Penkowa - One of the best experts on this subject based on the ideXlab platform.
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Metallothionein prevents neurodegeneration and central nervous system cell death after treatment with gliotoxin 6-Aminonicotinamide.
Journal of neuroscience research, 2004Co-Authors: Milena Penkowa, Albert Quintana, Javier Carrasco, Mercedes Giralt, Amalia Molinero, Juan HidalgoAbstract:Transgenic expression of interleukin-6 (IL-6) in the CNS under the control of the glial fibrillary acidic protein (GFAP) gene promoter (GFAP-IL6 mice) induces significant inflammation and neurodegeneration but also affords neuroprotection against acute traumatic brain injury. This neuroprotection is likely mediated by the IL-6-induced protective factors metallothioneins-I and -II (MT-I+II). Here we evaluate the neuroprotective roles of IL-6 vs. MT-I+II during 6-Aminonicotinamide (6-AN)-induced neurotoxicity, by using GFAP-IL6 mice and transgenic mice overexpressing MT-I (TgMT) as well as GFAP-IL6 mice crossed with TgMT mice (GFAP-IL6 x TgMT). 6-AN caused acute damage of brainstem gray matter areas identified by necrosis of astrocytes, followed by inflammatory responses. After 6-AN-induced toxicity, secondary damage was observed, consisting of oxidative stress, neurodegeneration, and apoptotic cell death. We hereby show that the primary injury caused by 6-AN was comparable in wild-type and GFAP-IL6 mice, but MT-I overexpression could significantly protect the brain tissue. As expected, GFAP-IL6 mice showed increased CNS inflammation with more gliosis, macrophages, and lymphocytes, including increased cytokine expression, relative to the other mice. However, GFAP-IL6 mice showed reduced oxidative stress (judged from nitrotyrosine, malondialdehyde, and 8-oxoguanine stainings), neurodegeneration (accumulation of neurofibrillary tangles), and apoptosis (determined from TUNEL and caspase-3). MT-I+II expression was significantly higher in GFAP-IL6 mice than in wild types, which may contribute to the IL-6-induced neuroprotection. In support of this, overexpression of MT-I in GFAP-IL6 x TgMT as well as TgMT mice protected the brainstem tissue significantly from 6-AN-induced toxicity and secondary brain tissue damage. Overall, the results demonstrate that brain MT-I+II proteins are fundamental neuroprotective factors, which in the future may become therapeutic agents.
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astrocyte targeted expression of interleukin 6 protects the central nervous system during neuroglial degeneration induced by 6 Aminonicotinamide
Journal of Neuroscience Research, 2003Co-Authors: Milena Penkowa, Albert Quintana, Mercedes Giralt, Amalia Molinero, Jordi Camats, Hanne Hadberg, Santiago Rojas, Iain L Campbell, Juan HidalgoAbstract:6-Aminonicotinamide (6-AN) is a niacin antagonist, which leads to degeneration of gray matter astrocytes mainly in the brainstem. We have examined the role of interleukin-6 (IL-6) in this degenerative process by using transgenic mice with astrocyte-targeted IL-6 expression (GFAP-IL6 mice). This study demonstrates that transgenic IL-6 expression significantly increases the 6-AN-induced inflammatory response of reactive astrocytes, microglia/macrophages, and lymphocytes in the brainstem. Also, IL-6 induced significant increases in proinflammatory cytokines IL-1, IL-12, and tumor necrosis factor-alpha as well as growth factors basic fibroblast growth factor (bFGF), transforming growth factor-beta, neurotrophin-3, angiopoietin, vascular endothelial growth factor, and the receptor for bFGF. In accordance, angiogenesis was increased in GFAP-IL6 mice relative to controls after 6-AN. Moreover, oxidative stress and apoptotic cell death were significantly reduced by transgenic IL-6 expression. IL-6 is also a major inducer in the CNS of metallothionein I and II (MT-I+II), which were significantly increased in the GFAP-IL6 mice. MT-I+II are antioxidants and neuroregenerative factors in the CNS, so increased MT-I+II levels in GFAP-IL6 mice could contribute to the reduction of oxidative stress and cell death in these mice.
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retracted m csf deficiency leads to reduced metallothioneins i and ii expression and increased tissue damage in the brain stem after 6 Aminonicotinamide treatment
Experimental Neurology, 2002Co-Authors: Milena Penkowa, Javier Carrasco, Christian Bjorn Poulsen, Juan HidalgoAbstract:6-Aminonicotinamide (6-AN) is a niacin antagonist, which leads to degeneration of gray-matter astrocytes followed by a vigorous inflammatory response. Macrophage colony stimulating factor (M-CSF) is important during inflammation, and in order to further clarify the roles for M-CSF in neurodegeneration and brain cell death, we have examined the effect of 6-AN on osteopetrotic mice with genetic M-CSF deficiency (op/op mice). The 6-AN-induced degeneration of gray-matter areas was comparable in control and op/op mice, but the numbers of reactive astrocytes, macrophages, and lymphocytes in the damaged areas were significantly decreased in op/op mice relative to controls. The levels of oxidative stress (as determined by using immunoreactivity for inducible nitric oxide synthase, nitrotyrosine, and malondialdehyde) and apoptotic cell death (as determined by using TUNEL and immunoreactivity for caspases and cytochrome c) were significantly increased in 6-AN-injected op/op mice relative to controls. From a number of antioxidant factors assayed, only metallothioneins I and II (MT-I+II) were decreased in op/op mice in comparison to controls. Thus, the present results indicate that M-CSF is an important growth factor for coping with 6-AN-induced central nervous system damage and suggest that MT-I+II are likely to have a significant role.
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metallothionein 1 2 protect the cns during neuroglial degeneration induced by 6 Aminonicotinamide
The Journal of Comparative Neurology, 2002Co-Authors: Milena Penkowa, Mercedes Giralt, Jordi Camats, Juan HidalgoAbstract:6-Aminonicotinamide (6-AN) is a niacin antagonist, which leads to degeneration of gray matter astrocytes. Metallothionein 1+2 (MT-1+2) are neuroprotective factors in the central nervous system (CNS), and to determine the roles for MT after 6-AN, we have examined transgenic mice overexpressing MT-1 (TgMTI* mice) after an i.p. injection with 6-AN. In control mice injected with 6-AN, astrocytes in specific gray matter areas of the brainstem showed degeneration. Reactive astrocytes surrounded the degenerated areas, which were heavily infiltrated by macrophages and T lymphocytes. MT-1+2 expression was significantly decreased in the damaged brainstem areas, but it increased in reactive astrocytes surrounding these areas and also in infiltrating macrophages. The levels of oxidative stress, as determined by immunoreactivity for inducible nitric-oxide synthase (iNOS), malondialdehyde (MDA), and nitrotyrosine (NITT), and the number of terminal deoxynucleotidyl transferase [TdT]-mediated deoxyuridine triphosphate [dUTP]-digoxigenin nick end labeling–positive (TUNEL+), caspase-3+ apoptotic cells were significantly increased in the brainstem of normal mice after 6-AN. In the TgMTI* mice, the 6-AN–induced tissue damage was decreased in comparison to control mice, and they showed significantly reduced numbers of recruited macrophages and T lymphocytes, and a drastic reduction of oxidative stress and apoptotic cell death. In addition, the accompanying reactive astrogliosis was increased in the transgenic mice. To further study the potential protective role of MT, we administered intraperitoneally Zn-MT-2 to 6-AN–injected normal mice and found essentially the same results as those obtained in TgMTI* mice. Thus, we hereby report that endogenous MT-1 overexpression and exogenous MT-2 treatment have significant neuroprotective roles during CNS pathological conditions. J. Comp. Neurol. 444:174–189, 2002. © 2002 Wiley-Liss, Inc.
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increased astrocytic expression of metallothioneins i ii in brainstem of adult rats treated with 6 Aminonicotinamide
Brain Research, 1997Co-Authors: Milena Penkowa, Juan Hidalgo, Torben MoosAbstract:Abstract The cerebral distribution of metallothioneins I and II (MT-I+II) was studied in adult rats subjected to i.p injection with the gliotoxin 6-Aminonicotinamide (6-AN). Grey matter regions of the brainstem heralded numerous OX-42-positive macrophages and microglia, indicating that 6-AN primarily caused damage to this part of the brain. In the grey matter regions infiltrated with OX-42-positive cells, astrocytes identified by anti-GFAP and MT-I+II antibodies were almost absent. By contrast, in the peripheral zone of the lesioned regions numerous reactive GFAP- and MT-I+II-positive astrocytes were observed. The blood–brain barrier (BBB) to serum albumin was compromised in the entire brainstem. The astrocytic expression of MT-I+II could reflect the brains needs to scavenge metal ions released from either damaged cells or plasma proteins entering the brain due to the injured BBB, as well as it could reflect the potential antioxidant function of MT-I+II.
In Kook Park - One of the best experts on this subject based on the ideXlab platform.
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6 Aminonicotinamide induces g1 arrest by elevating p27kip1 as well as inhibiting cdk2 cyclin e and p rb in imr32 neuroblastoma cell line
Animal Cells and Systems, 2005Co-Authors: Souad Ahmad Engliez, In Kook ParkAbstract:Abstract The effects of 6‐Aminonicotinamide (6‐AN) on viability of IMR32 neuroblastoma cells in the presence of ATP or NAD+ have been investigated. 6‐AN caused marked reduction in cell viability and similar observations were also made with cells treated with 6‐AN+ATP. However, cells treated with 6‐AN+NAD+ showed cell viability similar to untreated cells. Morphologically, 6‐AN and 6‐AN+ATP treated cells showed loss of neurites, polyhedric shapes, shrinkage of cell bodies and formation of lysed cells, while 6‐AN+NAD+ cells did not show any such changes. The flow cytometry analysis demonstrated that 6‐AN increased cell population in G0/G1 phase and decreased cell population in S and G2/M phase following a 72 h exposure. Western blot analysis showed that 6‐AN stimulated a substantial increase in the level of the cdk inhibitor p27kip1, but lowered the levels of cdk2, cyclin E and p‐Rb. However, cdc25A and p53R2 were not significantly affected. Immunofluorscence staining of p27kip1, cdk2, cyclin E and p‐Rb reve...
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effects of atp on the stability of enzymes against heat treatment in 6 Aminonicotinamide treated quail
The International Journal of Biochemistry & Cell Biology, 2002Co-Authors: Younbok Lee, Kyung Soo Nam, Il Soo Moon, Sook Shin, In Kook ParkAbstract:The stabilities of liver and pectoral muscle enzymes in 6-Aminonicotinamide (6-AN) treated quail against heat treatment in the presence and absence of added ATP were investigated. Only ATP level in the brain and pectoral muscle of 6-AN treated group was significantly reduced compared to the control group whereas ADP and AMP levels were not affected. In the thermal stability (55 degrees C) of liver enzymes, the activity of acetylcholinesterase (AChE) was not affected whereas the activities of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and lactate dehydrogenase (LDH) were significantly lowered (P<0.01). The addition of 1mM ATP to liver enzyme extracts of 6-AN group afforded 4- and 1.7-fold more protection for GAPDH and LDH, respectively (P<0.01). In liver, LDH appeared to be more protected by ATP than GAPDH. In muscle, however, GAPDH and AChE activity were significantly affected but not LDH. The addition of 1mM ATP to muscle enzyme extracts of 6-AN group afforded 1.7-fold more protection for GAPDH (P<0.01) but rather inactivated AChE. A marked reduction in ATP levels in muscle did not affect specifically muscle enzyme activities only since liver enzyme activities were also affected to the same degree as muscle.
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effects of neurotoxin 6 Aminonicotinamide on levels of enzyme activities and metabolites in quail plasma
The International Journal of Biochemistry & Cell Biology, 2001Co-Authors: Younbok Lee, In Kook ParkAbstract:Abstract Effects of 6-Aminonicotinamide (6-AN) on the levels of proteins, metabolites and enzyme activities in the plasma of Japanese quail were investigated. The concentrations of soluble proteins in the pectoral and hindlimb muscle of the 6-AN treated and the pair-fed groups were significantly reduced compared to the control group. In the plasma, the levels of total proteins and albumin were not affected, but the levels of globulin were significantly lower than those of the control and pair-fed groups. In contrast, the levels of glucose and creatine were significantly elevated. Cellulose acetate gel electrophoresis showed that 6-AN induced a new synthesis of prealbumin and also increased the levels of β-globulin relative to the control and pair-fed groups. In contrast, the levels of γ-globulin were markedly lower than those of the control group, whereas the levels of α-globulin were not affected. The specific activity of alkaline phosphatase of the 6-AN group was significantly lower than that of the control and pair-fed groups and that of aspartate aminotransferase only lower than that of the control group but not the pair-fed group. The specific activities of creatine phosphokinase and lactate dehydrogenase of the 6-AN group were the greatest among the three groups, whereas those of the pair-fed group were greater than those of the control group. The results suggest that 6-AN may interfere with the proper maintenance of energy charges and the immune system function.
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neurotoxin 6 Aminonicotinamide affects levels of soluble proteins and enzyme activities in various tissues of golden hamsters
The International Journal of Biochemistry & Cell Biology, 2000Co-Authors: Youngchul Yang, Jae Young Kim, In Kook ParkAbstract:Abstract The effects of neurotoxin 6-Aminonicotinamide (6-AN) on the levels of soluble proteins and enzyme activities in various tissues of golden hamsters were investigated. SDS–polyacrylamide gel electrophoresis showed that a soluble spinal cord protein with molecular mass 75.0 kDa was present at a higher concentration in the treated group compared to that in the control while that of a molecular mass 64.8 kDa appeared to be missing. However, there were no noticeable differences in protein concentrations observed with the cerebrum, brain stem, and cerebellum. Similarly, treatment with 6-AN decreased the concentration of a soluble protein in pectoral muscle having molecular mass 97.2 kDa and increased those having molecular masses 207.4 and 32.1 kDa. In the kidney, soluble proteins with molecular masses 176.6 kDa was missing and those of molecular masses 97.6, 49, 43.3, and 33.8 kDa were decreased whereas those of molecular masses 64.7 and 33.1 kDa were increased. In the testis the soluble proteins with molecular masses 125.4, 88.7, 69.0, 31.2, 19.1, and 17.4 kDa were missing and those of molecular masses 97.0, 51.3, 42.0, 33.0, 27.2, and 22.6 kDa were present in lower amounts whereas those of molecular masses 311.5, 75.0, 64.0, 54.1, and 53.2 kDa were present in higher amounts. The specific activity of 6-phosphogluconate dehydrogenase was markedly increased in the liver but that of other tissues was not affected. Acetylcholinesterase activity was markedly reduced in the spleen but was enhanced in the intestine. Monoamine oxidase activity was markedly reduced in the brain stem, cerebrum, kidney, and liver. The results suggest that the changes in levels of soluble proteins and enzyme activities shown with golden hamster tissues by 6-AN administration were quite different from those shown with quail tissues.
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effects of 6 Aminonicotinamide on levels of soluble proteins and enzyme activities in various tissues of japanese quail
The International Journal of Biochemistry & Cell Biology, 1998Co-Authors: Jae Young Kim, In Kook ParkAbstract:Abstract The effects of 6-Aminonicotinamide (6-AN) on the levels of soluble proteins and enzyme activities in various tissues of Japanese quail were investigated. SDS-polyacrylamide gel electrophoresis showed that the soluble proteins with molecular masses corresponding to 160.4 and 52.5 kDa were either missing or present at lower concentrations in the brain of the 6-AN treated group compared to those in the control group. The soluble liver proteins with molecular masses 200, 120 and 70.5 kDa were missing in the treated group compared to those in the control while those of a molecular mass 15.1 kDa were found to be present at higher concentrations. Similarly, treatment with 6-AN decreased the concentration of soluble proteins in pectoral muscle with molecular masses 92.3, 54.5, 43.5, 41.2, 34.5, 27.5, 20.1 and 17.5 kDa and increased those with molecular masses 96.5, 37.7, 25.0, 19.3, 16.6, 13.8 and 10.8 kDa. In the heart, soluble proteins with molecular mass 84.6 kDa were increased. There was a marked reduction in the treatment group in the concentration of NAD in pectoral muscle but not in other tissues. A similar observation was also made with total RNA levels. The specific activity of malic enzyme was markedly increased by 6-AN treatment in the kidney and pectoral muscle but reduced in the liver. 6-Phosphogluconate dehydrogenase and lactate dehydrogenase activities were markedly reduced in the liver. Glyceraldehyde-3-phosphate dehydrogenase activity was significantly decreased in liver and pectoral muscle. NAD glycohydrolase activity was markedly decreased in pectoral muscle. Acetylcholinesterase activity was markedly reduced in liver but was enhanced in pectoral muscle. The results suggest that the metabolic actions of 6-AN are specific for certain proteins in the liver and muscle with the effect being most pronounced in muscle. The effects are also quite distinct from those shown by its analogue 3-acetylpyridine.
Jason A. Koutcher - One of the best experts on this subject based on the ideXlab platform.
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quantitation of metabolic and radiobiological effects of 6 Aminonicotinamide in rif 1 tumor cells in vitro
Cancer Research, 1997Co-Authors: James C. Street, Alan A. Alfieri, Jason A. KoutcherAbstract:6-Aminonicotinamide (6AN) can be metabolized to 6-amino-NAD(P+), a competitive inhibitor of NAD(P+)-requiring processes, especially the pentose phosphate pathway (PPP) enzyme, 6-phosphogluconate dehydrogenase. The effect of 6AN on the flux of 1 and 6 13C-labeled glucose to lactate, via glycolysis and the PPP, was investigated using 1H-nuclear magnetic resonance. These studies showed that 6AN as a single agent caused a significant 89% (P < 0.0001) inhibition of glycolytic flux but had no detectable effect on the PPP. 31P-nuclear magnetic resonance studies of perifused RIF-1 cells indicated that 4 h of exposure to 6AN were sufficient to cause significant accumulation of 6-phosphogluconate, the substrate for this enzyme (P < 0.0001). A significant reduction in the phosphocreatine: inorganic phosphate ratio was observed under conditions that led to accumulation of 6-phosphogluconate (P < 0.006). Accumulation of 6-phosphogluconate and subsequent reduction in phosphocreatine correlated with significant potentiation of 6 Gy of irradiation by 6AN. These results suggest that the radiation enhancement effect of 6AN may be due to inhibition of glycolysis (mediated by 6-phosphogluconate) and the associated reduction in high-energy phosphates. Additional studies analyzing the metabolic effects of 6AN in combination with radiation are necessary to determine the role of inhibition of the PPP in 6AN enhancement of radiation.
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effect of 6 Aminonicotinamide on the pentose phosphate pathway 31p nmr and tumor growth delay studies
Magnetic Resonance in Medicine, 1996Co-Authors: Jason A. Koutcher, James C. Street, Alan A. Alfieri, Cornelia Matei, Kristen L Meyer, Daniel S MartinAbstract:6-Aminonicotinamide (6AN) has been shown to enhance radiosensitivity in vitro, although previous in vivo studies failed to show an effect. 31P NMR spectra were obtained by using a one-dimensional chemical shift imaging technique on a first generation transplant of the CD8FI spontaneous mammary carcinoma tumor model. Spectra were obtained both before and 10 h after treatment with 6AN (20 mg/kg). Changes in pH, nucleoside triphosphate/inorganic phosphate, and phosphocreatine/ inorganic phosphate measured at 10 h post-6AN were not significant. A new peak was detected 10 h post-6AN, which was assigned to 6-phosphogluconate (6PG), indicating inhibition of the pentose phosphate pathway (PPP). Based on the spectral data demonstrating inhibition of the PPP at 10 h post-6AN, tumor-bearing mice were irradiated (15 Gy x 3 fractions) on Days 1, 10 or 11, and 21 10 h after administration of 6-Aminonicotinamide (20 mg/kg). Tumor-bearing mice receiving 6AN alone (20 mg/kg x 3), radiation alone (15 Gy x 3), or saline were also studied. Tumor growth delay studies indicated that 6AN alone induced a small but significant tumor growth delay (4.3 +/- 0.8 days). Radiation alone induced a tumor growth delay of 34.5 +/- 2.7 days. Treatment with 6AN followed by radiation induced a tumor growth delay of 57.0 +/- 3.8 days. This was significantly greater than the TGD values for treatment with 6AN alone or radiation (P < 0.01). No complete regressions were noted after treatment with 6AN or radiation alone. Concomitant therapy with 6AN plus radiation yielded 6/28 complete regressions (21%), which was significantly greater than radiation (P < 0.05) or 6AN alone (P < 0.01) on this mammary carcinoma.
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13C and 31P NMR investigation of effect of 6-Aminonicotinamide on metabolism of RIF-1 tumor cells in vitro.
The Journal of biological chemistry, 1996Co-Authors: James C. Street, Umar Mahmood, Douglas Ballon, Alan A. Alfieri, Jason A. KoutcherAbstract:The effect of 6-Aminonicotinamide on the metabolism of RIF-1 tumor cells was investigated using 13C and 31P NMR spectroscopy. 6-Aminonicotinamide can be metabolized to 6-amino-NAD(P), a competitive inhibitor of NAD(P)-requiring processes. 40 microM 6-Aminonicotinamide led to an inhibition of 6-phosphogluconate dehydrogenase and an accumulation of 6-phosphogluconate. A subsequent accumulation of the 6-phosphogluconate precursor 6-phosphoglucono-delta-lactone was observed in the 13C NMR spectrum. These metabolites were shown to be intracellular, although a small amount of leakage of 6-phosphoglucono-delta-lactone occurred. The intracellular concentrations of 6-phosphogluconate and 6-phosphoglucono-delta-lactone were 1.9 +/- 0.8 micromol/108 cells (+/-1 standard deviation) and 0.8 +/- 0.4 micromol/10(8) cells, respectively, after 15 h. Glucose utilization and lactate production were significantly inhibited by 6-Aminonicotinamide (both p < 0.05), indicating inhibition of glycolysis. 31P NMR data showed that phosphocreatine was significantly depleted in cells exposed to 6-Aminonicotinamide (p < 0.05). Exposure of RIF-1 cells to 6-Aminonicotinamide prior to 3- or 6-Gy x-irradiation induced a supra-additive cell kill, indicating that 6-Aminonicotinamide is acting as a radiosensitizer. There was no effect of 6-Aminonicotinamide alone or when the drug was given postradiation, suggesting that its mechanism of action may be by inhibition of radiation-induced repair.
Rajeev Varshney - One of the best experts on this subject based on the ideXlab platform.
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2 deoxy d glucose and 6 Aminonicotinamide mediated nrf2 down regulation leads to radiosensitization of malignant cells via abrogation of gsh mediated defense
Free Radical Research, 2012Co-Authors: Pradeep Kumar Sharma, Rajeev VarshneyAbstract:Enhanced level of nuclear erythroid-related factor-2 (Nrf2) has been associated with cancer chemo/radioresistance. Therefore, the role of Nrf2 in radiosensitization of malignant cells induced by a combination of 2-deoxy-D-Glucose (2-DG) and 6-Aminonicotinamide (6-AN) was investigated. Two established human malignant cells lines namely KB (head and neck squamous carcinoma) and BMG-1 (cerebral glioma) were used. Following treatment with a combination of 2-DG (5 mM) and 6-AN (5 μM), irradiated (2Gy) KB and BMG-1 cells were assessed for protein level of Nrf2, Keap1 and γ-glutamylcysteine synthetase (γ-GCS) by western blotting and mRNA expression of γ-GCS, glutathione reductase (GR) and glutathione peroxidase (GPx1) by RT-PCR at 24 hours post treatment. A significant decrease in the level of Nrf2 with a concomitant increase in Keap1 was observed in both the irradiated malignant cells at 24 hours following treatment with combination (2-DG + 6-AN). Down regulation of γ-GCS, GR and GPx1 at 24 hours following treatment with combination (2-DG + 6-AN) resulted in abrogation of glutathione (GSH)-mediated defense in both the irradiated malignant cells. Eventual accumulation of ROS led to radiosensitization of both the malignant cells. These results indicate that deregulated Nrf2-Keap1 signalling leads to the radiosensitization of malignant cells due to abrogated glutathione defense. Metabolic modification-mediated down regulation of Nfr2 and its downstream signalling may have a potential of improving tumour radiotherapy.
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a combination of 2 deoxy d glucose and 6 Aminonicotinamide induces cell cycle arrest and apoptosis selectively in irradiated human malignant cells
Tumor Biology, 2012Co-Authors: Richa Bhardwaj, Pradeep Kumar Sharma, S P S Jadon, Rajeev VarshneyAbstract:Previously, we have shown that a combination of metabolic modifiers 2-deoxy-d-glucose (2-DG) and 6-Aminonicotinamide (6-AN) results in oxidative stress mediated radiosensitization of malignant cells via mitochondrial dysfunction and non-coordinated expression of antioxidant defense, besides inhibition of repair and recovery. In the present study, our objective was to study, in a panel of human malignant cells of various origins (lung carcinoma, squamous carcinoma, oral carcinoma, and glioblastoma), if the inhibitory activity of combination (2-DG+6-AN+2Gy) against tumor growth could be considered a general phenomenon and to determine its effect on the cell cycle. The results revealed that combination (2-DG+6-AN+2Gy) treatment result in significant cell growth inhibition and induced ROS generation in all cancer cells studied. The anti-proliferative effect was related to the ability of combination (2-DG+6-AN+2Gy) to provoke growth inhibition at the G2/M arrest and apoptosis. Furthermore, combination (2-DG+6-AN+2Gy) induced G2/M arrest is closely correlated to decreased cyclin A, cyclin B1, and cdc2 levels.
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a combination of 2 deoxy d glucose and 6 Aminonicotinamide induces oxidative stress mediated selective radiosensitization of malignant cells via mitochondrial dysfunction
Tumor Biology, 2011Co-Authors: Richa Bhardwaj, Rajeev Varshney, Pradeep Kumar Sharma, Suryaprakash Singh JadonAbstract:Oxidative stress-mediated mitochondrial dysfunction is known to induce intrinsic pathway of apoptosis. Previously, we have shown that a combination of metabolic modifiers 2-deoxy-D-glucose (2-DG) and 6-Aminonicotinamide (6-AN) results in oxidative stress-mediated radiosensitization of malignant cells via noncoordinated expression of antioxidant defense. We now show that the combination (2-DG + 6-AN + 2Gy) induces significant alterations in mitochondrial membrane potential and oxidative damage to lipid and proteins selectively in malignant cells resulting in the release of cytochrome c from mitochondria and increase in Bax/Bcl-2 ratio stimulating intrinsic pathway of apoptosis, besides enhancing the mitotic death linked to cytogenetic damage. These results highlight the role of mitochondrial dysfunction in selective radiosensitization by 2-DG + 6-AN, besides inhibition of energy-linked DNA repair processes and generation of oxidative stress reported earlier.
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radiosensitization by 6 Aminonicotinamide and 2 deoxy d glucose in human cancer cells
International Journal of Radiation Biology, 2005Co-Authors: Rajeev Varshney, B S Dwarakanath, Viney JainAbstract:The aim was to exploit simultaneous inhibition of glycolytic and pentose phosphate pathways of energy production for radiosensitization using 2-deoxy-D-glucose (2-DG) and 6-Aminonicotinamide (6-AN) in transformed mammalian cells. Two human tumour cell lines (cerebral glioma, BMG-1 and squamous carcinoma cells 4197) were investigated. 2-DG and/or 6-AN added at the time of irradiation were present for 4 h after radiation. Radiation-induced cell death (macrocolony assay), cytogenetic damage (micronuclei formation), cell cycle delay (bromodeoxyuridne (BrdU) pulse chase), apoptosis (externalization of phosphotidylserine (PS) by annexin V), chromatin-bound proliferation cell nuclear antigen (PCNA) and cellular glutathione (GSH) levels were investigated as parameters of radiation response. The presence of 2-DG (5 mM) during and for 4 h after irradiation increased the radiation-induced micronuclei formation and cell death, and caused a time-dependent decrease in GSH levels in BMG-1 cells while no significant effects could be observed in 4197 cells. 6-AN (5 microM) enhanced the radiosensitivity of both cell lines and reduced the GSH content by nearly 50% in gamma-irradiated 4197 cells. Combining 2-DG and 6-AN caused a profound decrease in the GSH content and enhanced the radiation damage in both the cell lines by increasing mitotic and apoptotic cell death. Further, the combination (2-DG + 6-AN) enhanced the radiation-induced G2 block, besides arresting cells in S phase and inhibited the recruitment of PCNA. The combination of 2-DG and 6-AN enhances radiation damage by modifying damage response pathways and has the potential for improving radiotherapy of cancer.
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radiosensitization of murine ehrlich ascites tumor by a combination of 2 deoxy d glucose and 6 Aminonicotinamide
Technology in Cancer Research & Treatment, 2004Co-Authors: Rajeev Varshney, Seema Gupta, B S DwarakanathAbstract:Enhanced radiosensitizing effects of a combination of 2-deoxy-D-glucose (2-DG), a glycolytic inhibitor and 6-Aminonicotinamide (6-AN) an analogue of nicotinamide, which inhibits hexose monophosphate shunt (HMP) have been demonstrated in vitro. The purpose of the present studies is to investigate in vivo effects of this combination in Ehrlich ascites tumor (EAT) bearing mice. EAT tumor was grown in Swiss albino strain A mice. Treatment induced growth delay and tumor free animal survival were evaluated as parameters of radiation response. Focal irradiation of the tumor with a single fraction of 10 Gy induced a moderate delay in tumor growth but did not lead to complete regression of the tumor. Intravenous administration of either 6-AN or 2-DG immediately before irradiation enhanced radiation-induced growth delay with a cure rate of 45%. However, administration of a combination of 2-DG (2 g/kg b.wt.) and 6-AN (2 mg/kg b.wt.) immediately before irradiation led to complete regression of tumor in 80% animals resulting in survival of more than 300 days. A similar response (approximately 80%) was observed when 2-DG dose was reduced to 1 g/kg in combination with 6-AN. It is concluded that 6-AN enhances the radiosensitizing effects of 2-DG and the combination may have potential application in improving radiotherapy of tumors.
