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C J Epstein

Publications and source records attributed to C J Epstein.

At least 73 records · Page 4Linked to original sources
PubMed1997

Midbrain dopaminergic neuronal degeneration in a transgenic mouse model of familial amyotrophic lateral sclerosis.

Familial amyotrophic lateral sclerosis has been linked in 15% of families to mutations in the gene encoding for copper-zinc superoxide dismutase (Cu/Zn-SOD), a key enzyme in the cellular defense mechanisms against free radical attack. We used a transgenic mouse model of familial amyotrophic lateral sclerosis (transgenic G1H mice) based on expression of mutant human Cu/Zn-SOD to examine the influence of the transgene expression on midbrain dopaminergic neurons, cells that contain conspicuous amounts of this enzyme. At the time that 50% of motor neurons of the spinal cord were lost, we observed concurrent reductions in dopamine levels in the caudate-putamen and the nucleus accumbens of transgenic G1H mice. In addition, numbers of tyrosine hydroxylase-immunostained neurons were significantly reduced in both the substantia nigra (26%) and the ventral tegmental area (16%) compared to those in their nontransgenic littermates. Similar abnormalities were not observed in the brains of transgenic mice overexpressing wild-type Cu/Zn-SOD. These findings indicate that overexpression of the mutated Cu/Zn-SOD protein caused a significant loss of midbrain dopaminergic neurons in addition to the loss of spinal motor neurons. The potential of the mutated enzyme to induce cell death extending beyond the motor neurons is consistent with the description of substantia nigra degeneration in some patients with familial amyotrophic lateral sclerosis. Furthermore, if mutated Cu/Zn-SOD is conclusively shown to kill cells by oxidative stress, such an observation would be in keeping with the known sensitivity of dopaminergic neurons to free radical attack.

Amyotrophic Lateral Sclerosis↗
PubMed1997

Edema formation exacerbates neurological and histological outcomes after focal cerebral ischemia in CuZn-superoxide dismutase gene knockout mutant mice.

In a variety of studies. CuZn-superoxide dismutase (CuZn-SOD) has been shown to protect against ischemic brain injury. A possible role for CuZn-SOD-related modulation of neuronal viability has been suggested by the finding that CuZn-SOD inhibits brain edema formation following various kinds of neurological insults. We have evaluated the role of CuZn-SOD on brain edema formation following focal cerebral ischemia in mice bearing a disruption of the CuZn-SOD gene (Sod1). Homozygous mutants (Sod1-/-) had no detectable CuZn-SOD activity and heterozygous mutants (Sod1+/-) showed a 50% decrease compared to wild-type mice. Sod1-/- mice showed a high level of blood-brain barrier (BBB) disruption shortly after 1 hr of middle cerebral artery occlusion and 100% mortality at 24 hr following ischemia. Sod1+/- mice showed a moderate level of BBB disruption and 30% mortality. The Sod1+/- animals had increased infarct volume and brain swelling, accompanying exacerbated neurological deficits at 24 hr following ischemia. These results indicate the important role of superoxide anions in the development of brain edema after focal cerebral ischemia and suggest the possibility that brain edema formation may contribute to the exacerbation of ischemic brain injury and neurological deficits in knockout mutant mice.

Animals↗
PubMed1997

Novel mutations in an otherwise strictly conserved domain of CuZn superoxide dismutase.

All mutations in the human gene for CuZn superoxide dismutase (CuZnSOD) reported to date are associated with the disease amyotrophic lateral sclerosis (ALS). These mutations, mostly of a familial nature (ALS 1, MIM 105400), span all of the coding region of this enzyme except for a highly conserved centrally located domain that includes all of exon III. We describe the identification and characterization of two mutations in this region, both found in mice. One mutation, a glutamate to lysine amino acid substitution was found in position 77 (E77K) of the strain SOD1/Ei distributed by the Jackson Laboratory. The other mutation, a lysine to glutamate substitution at position 70 (K70E) of a human transgene, was discovered in mouse line TgHS/SF-155. Enzyme activity measurements and heterodimer analysis of the CuZn SOD variant in SOD1/Ei suggest a mild loss of activity, which differs from the enzyme activity losses detected in patients with autosomal dominant ALS 1. Similarly, the presence of the mutant transgene in TgHS/SF 155 does not produce any phenotypic manifestations.

Amino Acid Sequence↗
PubMed1997

Transgenic murine dopaminergic neurons expressing human Cu/Zn superoxide dismutase exhibit increased density in culture, but no resistance to methylphenylpyridinium-induced degeneration.

Primary dopaminergic neuronal cultures with increased superoxide dismutase (SOD) activity were established for studying the role of superoxide anion (O2-) in 1-methyl-4-phenylpyridinium (MPP+)-induced degeneration of dopamine (DA) neurons. Mean SOD activity in cultures prepared from transgenic (human) Cu/Zn SOD (hSOD1) mice was 2.46-2.60 times greater than in cultures prepared from nontransgenic control mice. After 1 and 2 weeks in culture, the mean density of DA neurons [number of tyrosine hydroxylase-immunoreactive (TH-ir) cells per visual field] was significantly higher in cultures prepared from transgenic mice compared with those prepared from nontransgenic control mice (4.55-5.63 TH-ir neurons per field in hSOD1 cultures vs. 2.66-2.8 TH-ir neurons per field in control cultures). However, uptake of [3H]DA relative to uptake of [3H]GABA was only slightly greater in hSOD1 cultures than in normal cultures (14.1 nmol of DA/100 nmol of GABA vs. 12.1 nmol of DA/100 nmol of GABA). Resistance to MPP+ toxicity was not significantly different from that in normal cultures when based on density of surviving TH-ir cell bodies (EC50 = 0.54 microM in hSOD1 and EC50 = 0.37 microM in normal cultures). A more sensitive measure of DA neuron integrity and function ([3H]DA uptake) also failed to demonstrate increased resistance of hSOD1 cultures to the toxin (EC50 = 73.7 nM in hSOD1 and EC50 = 86.2 nM in controls). These results do not support the hypothesis that neurotoxicity of the active metabolite of MPTP, MPP+, is mediated by generation of O2- in the cytoplasm. Nevertheless, mesencephalic cultures with increased hSOD1 activity appear to survive better than normal control cultures in the oxidatively stressful environment of cell culture incubators, and such mesencephalic cells may be useful for cell grafting studies in animal models of Parkinson's disease.

1-Methyl-4-phenylpyridinium↗
PubMed1997

Effects of wild-type and mutated copper/zinc superoxide dismutase on neuronal survival and L-DOPA-induced toxicity in postnatal midbrain culture.

Mutations in the free radical-scavenging enzyme copper/zinc superoxide dismutase (Cu/Zn-SOD) are associated with neuronal death in humans and mice. Here, we examine the effects of human wild-type (WT SOD) and mutant (Gly93 --> Ala; G93A) Cu/Zn-SOD enzyme on the fate of postnatal midbrain neurons. One-week-old cultures from transgenic mice expressing WT SOD enzyme had significantly more midbrain neurons and fewer necrotic and apoptotic neurons than nontransgenic cultures. In contrast, 1-week-old cultures from transgenic G93A mice expressing mutant SOD enzyme had significantly fewer midbrain neurons and more necrotic and apoptotic neurons than nontransgenic cultures. To subject postnatal midbrain neurons to oxidative stress, cultures were incubated with L-DOPA. L-DOPA at 200 microM caused approximately 50% loss of tyrosine hydroxylase (TH)-positive neurons in nontransgenic cultures and even greater loss in transgenic G93A cultures; no alterations were noted in GABA neuron numbers. In contrast, 200 microM L-DOPA did not cause any significant reductions in TH-positive or GABA neuron numbers in transgenic WT SOD cultures. L-DOPA at 50 microM had opposite effects, in that it significantly increased TH-positive, but not GABA neuron numbers in transgenic WT SOD and G93A and in nontransgenic cultures. These results indicate that increased amounts of WT SOD enzyme promote cell survival and protect against L-DOPA-induced dopaminergic neurotoxicity, whereas increased amounts of mutated Cu/Zn-SOD enzyme have inverse effects. As the spontaneous loss and L-DOPA-induced loss of postnatal dopaminergic midbrain neurons appear to be mediated by free radicals, our study supports the view that mutated Cu/Zn-SOD enzyme kills cells by oxidative stress.

Age Factors↗
PubMed1997

DNA fragmentation and Prolonged expression of c-fos, c-jun, and hsp70 in kainic acid-induced neuronal cell death in transgenic mice overexpressing human CuZn-superoxide dismutase.

Kainic acid (KA) neurotoxicity was examined in transgenic (Tg) mice overexpressing human CuZn-superoxide dismutase (SOD-1). The doses of KA required to produce seizures, the severity of the seizures, and the regions damaged were similar in SOD-1 Tg and non-transgenic wild-type mice. Intraperitoneal KA injection induced seizure-related neuronal damage in the CA3 and CA1 regions of the hippocampus and in other regions of the brain in both SOD-1 Tg and wild-type mice. These damaged neurons were labeled with the terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL) technique up to 72 h, although no significant difference in the number of TUNEL-positive neurons was observed between SOD-1 Tg and wild-type mice. In situ hybridization showed that c-fos, c-jun, and hsp70 genes were expressed in the hippocampus, cortex, and other regions of the brain after KA treatment. The expression of these genes was maximal 1 to 4 h following KA treatment but persisted longer in the hippocampus and other regions in SOD-1 Tg compared with wild-type mice; however, cell death in the hippocampus, assessed using cresyl violet staining, was similar in SOD-1 Tg and wild-type mice. The data show that superoxide radicals modulate both immediate early gene and heat shock gene expression after KA-induced seizures. The prolonged expression of c-fos, c-jun, and hsp70 in SOD-1 Tg compared with wild-type mice may indicate that hippocampal neurons survive longer in SOD-1 Tg than in wild-type animals; however, cell death as well as the seizure threshold, seizure severity and the pattern of regional vulnerability were not affected substantially by increased levels of SOD in the brain.

Animals↗
PubMed1997

Modulation of P-selectin expression in the postischemic intestinal microvasculature.

The dual radiolabeled monoclonal antibody technique was used to 1) define the magnitude and kinetics of P-selectin expression in murine small intestine exposed to ischemia-reperfusion (I/R), and 2) determine the factor(s) responsible for initiating this response. Within 10 min after release of a 20-min arterial occlusion, intestinal P-selectin expression increased two- to threefold compared with control values. Peak (4-fold) expression of P-selectin was noted at 5 h after reperfusion, returning to the control value at 24 h. The early (10-30 min) I/R-induced upregulation of P-selectin appears to reflect mobilization of a performed pool of the adhesion molecule, whereas the later (5 h) rise appears to be transcription dependent. The early increase in P-selectin expression was not inhibited by pretreatment with either oxypurinol (inhibits xanthine oxidase), diphenhydramine (H1-receptor antagonist), or MK-571 (leukotriene C4/D4 antagonist), nor was it blunted in transgenic mice expressing three times the normal level of copper-zinc superoxide dismutase or in mast cell-deficient mice. However, significant inhibition was noted after treatment with either MK-886 (5-lipoxygenase inhibitor) or a nitric oxide (NO) donor (diethylenetriamine/NO). These findings indicate that the early I/R-induced increase in intestinal P-selectin expression is mediated by a 5-lipoxygenase-dependent NO-inhibitable mechanism.

Animals↗
PubMed1997

Fatty streak formation in fat-fed mice expressing human copper-zinc superoxide dismutase.

Studies in vitro have shown that copper-zinc superoxide dismutase (CuZn-SOD) inhibits a number of events putatively involved in atherogenesis, including cell-mediated oxidation of LDL. To investigate whether increased activity of CuZn-SOD reduces atherogenesis in vivo, we examined diet-induced fatty streak formation in CuZn-SOD transgenic mice (n = 24) as compared with their nontransgenic littermates (n = 28). Transgenic animals were originally created by introduction of an EcoRI-BamHI human genomic DNA fragment containing the CuZn-SOD gene and its regulatory elements into B6SJL zygotes. For the current studies, the transgene was bred for 12 generations into the atherosclerosis-susceptible C57BL/6 background. Animals were fed atherogenic diets (15% fat, 1.25% cholesterol, 0.5% Na cholate) starting at 100 weeks of age and extending for 18 weeks. At the end of the diet period, aortic SOD activity was two-fold higher in transgenics than nontransgenics (mean +/- SE: 46.7 +/- 5.8 versus 20.1 +/- 2.4 units/mg of protein, P < .001). Levels of protein-bound amino acid oxidation products (meta-, ortho-, and dityrosine) were either similar or lower in aorta and heart from transgenics as compared with nontransgenics, suggesting that amplification of CuZn-SOD activity above the normal complement had modest inhibitory effects on basal oxidative stress in these tissues. CuZn-SOD overexpression did not reduce the extent of lesion development as analyzed by quantitative lipid staining of serial sections of the proximal aorta; mean lesion areas (+/- SE) were 997 +/- 478 and 943 +/- 221 mu 2 in transgenics and nontransgenics, respectively. Notably, the range of values for lesion area was 2.2-fold greater in transgenics (0-8403 versus 0-3868 mu 2 in nontransgenics). Moreover, within this group, lesion area showed a significant positive correlation with SOD activity (r = .611, P < .03). These results do not support an antiatherogenic effect of Cu-Zn-SOD over expression and raise the possibility that high tissue SOD activity may potentiate atherogenesis in fat-fed atherosclerosis-susceptible mice [corrected].

Amino Acids↗
PubMed1997

Overexpression of CuZn-superoxide dismutase reduces hippocampal injury after global ischemia in transgenic mice.

BACKGROUND AND PURPOSE: The role of copper, zinc-superoxide dismutase (CuZn-SOD) in hippocampal injury after transient global ischemia was studied using transgenic (Tg) mice and wild-type littermates. METHODS: Global ischemia was induced by bilateral common carotid artery occlusion. The hemisphere with the hypoplastic posterior communicating artery was determined and then the hippocampus in this hemisphere was evaluated qualitatively using a score of 0 to 4 and quantitatively using an image analyzer. RESULTS: Hippocampal injury was reduced in Tg mice after both 5 and 10 minutes of ischemia. In the 5-minute ischemia group, the mean score of the injury was significantly lower in Tg than nontransgenic (nTg) mice at 3 days. In the 10-minute group, the hippocampal injury was reduced more in Tg than nTg mice at 1 day. Quantitative evaluation by an image analyzer confirmed the qualitative data. Neurons with fragmented DNA were also studied in the hippocampal injury. In the 5-minute group, despite the reduction of the injury in Tg mice, their neurons with fragmented DNA were relatively increased at 1 day. In the 10-minute group, this ratio was almost the same in both nTg and Tg mice. CONCLUSIONS: CuZn-SOD plays a protective role in the pathogenesis of selective hippocampal injury after brief ischemia, whether the insult is relatively mild or intense. Furthermore, CuZn-SOD may reduce both necrotic and DNA fragmented neuronal death after global ischemia.

Animals↗
PubMed1996

Central nervous system expression of HIV-1 Gp120 activates the hypothalamic-pituitary-adrenal axis: evidence for involvement of NMDA receptors and nitric oxide synthase.

The impact of HIV-1 expression in the brain on the development of AIDS is unknown. In the present study, we examined the hypothalamic-pituitary-adrenal (HPA) axis in a transgenic model in which expression of the HIV-1 envelope glycoprotein gp120 induced central nervous system (CNS) damage similar to that seen in HIV-1-infected patients. Compared with nontransgenic littermates, gp120 transgenic mice showed significant increases in plasma corticosterone and adrenocorticotrophic hormone (ACTH) levels and pituitary ACTH content. To determine whether this activation of the HPA axis could be mediated by ACTH secretagogues, the effect of recombinant gp120 on the release of these factors from hypothalamic slices was investigated in vitro. Recombinant gp120 induced release of the ACTH secretagogue arginine vasopressin from nontransgenic hypothalamic slices in a calcium-dependent fashion. This effect was inhibited by antagonists of N-methyl-D-aspartate (NMDA) receptors or of nitric oxide synthase (NOS), suggesting a role for NMDA receptor stimulation and NOS activity. Further evidence for a role of free radicals was obtained from bigenic mice coexpressing gp120 and the free radical scavenger human copper/zinc superoxide dismutase which showed normal corticosterone levels. This might relate to superoxide dismutase-mediated scavenging of superoxides generated by NOS. These findings demonstrate that CNS expression of a viral envelope protein can activate the HPA axis and thereby alter peripheral levels of immunomodulatory hormones.

Adrenocorticotropic Hormone↗
PubMed1996

Developmental abnormalities and age-related neurodegeneration in a mouse model of Down syndrome.

To study the pathogenesis of central nervous system abnormalities in Down syndrome (DS), we have analyzed a new genetic model of DS, the partial trisomy 16 (Ts65Dn) mouse. Ts65Dn mice have an extra copy of the distal aspect of mouse chromosome 16, a segment homologous to human chromosome 21 that contains much of the genetic material responsible for the DS phenotype. Ts65Dn mice show developmental delay during the postnatal period as well as abnormal behaviors in both young and adult animals that may be analogous to mental retardation. Though the Ts65Dn brain is normal on gross examination, there is age-related degeneration of septohippocampal cholinergic neurons and astrocytic hypertrophy, markers of the Alzheimer disease pathology that is present in elderly DS individuals. These findings suggest that Ts65Dn mice may be used to study certain developmental and degenerative abnormalities in the DS brain.

Aging↗
PubMed1996

Expression of hsp70 mRNA is induced in the brain of transgenic mice overexpressing human CuZn-superoxide dismutase following transient global cerebral ischemia.

We examined hsp70 mRNA expression in the brains of transgenic (Tg) mice overexpressing CuZn-superoxide dismutase and in wild-type (Wt) littermates after 3 min of bilateral common carotid artery occlusion. Significant induction of hsp70 mRNA occurred in the hippocampus, the cortex, and other brain regions of the Tg mice 4 h after ischemia compared to the Wt mice. However, there was no histological damage in the brains of Tg and Wt mice as assessed by both Cresyl violet staining and by TUNEL staining for DNA fragmentation. These data suggest that high levels of CuZn-superoxide dismutase activity increase hsp70 mRNA expression and that intense hsp70 mRNA expression does not predict neuronal damage, even in vulnerable hippocampal CA1 neurons.

Animals↗
PubMed1996

Werner syndrome: entering the helicase era.

Werner syndrome is a rare autosomal recessive disorder that mimics some of the characteristics of aging. The gene for this disorder has recently been identified as a helicase of the recQ subclass. Other phenotypically distinctive disorders caused by different helicase mutations include Bloom syndrome, Cockayne syndrome, xeroderma pigmentosum and trichothiodystrophy. Possible mechanisms by which helicases might produce the variable phenotypes are discussed. These include altered nucleotide excision repair and RNA polymerase II-mediated transcription. The discovery of the helicase defect in Werner syndrome provides a road map for future study of its unique pathogenesis and conceivable, but unproved, relationship to the aging process.

Adenosine Triphosphatases↗
PubMed1996

The influence of oxygen free radicals on the permeability of the monolayer of cultured brain endothelial cells.

Free radicals have been implicated in the pathogenesis of vasogenic brain edema caused by ischemic or traumatic injury. It has been reported that in transgenic mice overexpressing the human CuZn-superoxide dismutase, brain edema is decreased in many cerebral disorders. To investigate the effects of free radicals on the permeability of the blood brain barrier, we established an in vitro model system of the blood-brain barrier using brain endothelial cells cultivated from transgenic mice and non-transgenic mice. The blood-brain barrier model is originated by a monolayer of brain endothelial cells cultured on a membrane which has 0.45-micron pores. Electrical resistance across the cell monolayer, which reflects the paracellular flux of ionic molecules, was measured. The blood-brain barrier models were incubated with menadione (vitamin K3, an intracellular O2- producing agent), and segmental changes in the electrical resistance across the monolayer were compared between the transgenic and the non-transgenic mice. Superoxide dismutase activity of the cultured brain endothelial cells was 1.7 times higher in the transgenic than in the non-transgenic mice (n = 3, P < 0.001). The electrical resistance was reduced by menadione in the transgenic but not in the non-transgenic mice (n = 7, P < 0.05) in the early stage. Moreover, desferroxamine mesylate (Fe2+ chelating agent) inhibited the menadione-induced early decrease in electrical resistance in the transgenic mice (n = 7, P < 0.05). These results suggest that the permeability of the blood-brain barrier may be affected by hydroxyl radicals and/or peroxynitrite rather than the O2- itself.

Animals↗
PubMed1996

Increased superoxide dismutase activity improves survival of cultured postnatal midbrain neurons.

Copper/zinc superoxide dismutase (Cu/Zn-SOD) is a major free radical scavenging enzyme. Increased Cu/Zn-SOD activity protects cells against oxidative stress mediated by different mechanisms. However, there is also in vitro and in vivo evidence that, in the absence of abnormal oxidative stress, chronic increased Cu/Zn-SOD activity is detrimental to living cells. To address this issue, we examined the fate of mature midbrain neurons from transgenic mice expressing human Cu/Zn-SOD and from their nontransgenic littermates. Midbrain from transgenic pups had about threefold higher Cu/Zn-SOD activity than that from nontransgenic pups. Virtually all transgenic neurons were strongly immunoreactive for human Cu/Zn-SOD protein in their cell bodies and processes. The number of midbrain neurons decreased over time in both transgenic and nontransgenic cultures, but to a significantly smaller extent in the transgenic cultures. Postnatal midbrain neurons died by either necrosis or apoptosis, and increased Cu/Zn-SOD activity attenuated both forms of cell death. Furthermore, increased Cu/Zn-SOD activity better prevented the loss of dopaminergic neurons than GABAergic neurons. We also found that neuronal processes were dramatically denser in transgenic cultures than in nontransgenic cultures. These results indicate that chronic increased Cu/Zn-SOD activity does not appear to be detrimental, but rather promotes cell survival and neuronal process development in postnatal midbrain neurons, probably by providing more efficient detoxification of free radicals. They also show that increased Cu/Zn-SOD activity does not seem to play a critical role in determining the mode of cell death in this culture system.

Animals↗
PubMed1996

Antisense manganese superoxide dismutase mRNA inhibits the antiviral action of interferon-gamma and interferon-alpha.

Manganese superoxide dismutase (MnSOD) is induced by interferon-gamma (IFN-gamma) in various cell lines. To determine whether MnSOD plays a role in the antiviral action of IFN-gamma, we employed an antisense strategy to inhibit the expression of MnSOD in the human melanoma cell line, A375. Three antisense-containing clones that exhibited reduced induction of MnSOD were investigated with respect to their response to the antiviral protective effects of IFN-gamma and IFN-alpha. We observed a striking decrease in the ability of IFN-gamma to protect antisense clones from vesicular stomatitis virus infection (VSV). The IFN-alpha induced antiviral state was also impaired, but to a lesser degree than was observed with IFN-gamma. We excluded the possibility that these effects were caused by a higher sensitivity of the antisense cells to VSV itself and found that the antisense clones actually were less sensitive to VSV. Therefore, we conclude that MnSOD is involved in the establishment of the IFN-gamma-induced antiviral state and to a lesser degree in the antiviral actions of IFN-gamma.

Antiviral Agents↗