Non-Fickian diffusion and the accumulation of methane bubbles in deep-water sediments.

In the absence of fractures, methane bubbles in deep-water sediments can be immovably trapped within a porous matrix by surface tension. The dominant mechanism of transfer of gas mass therefore becomes the diffusion of gas molecules through porewater. The accurate description of this process requires non-Fickian diffusion to be accounted for, including both thermal diffusion and gravitational action. We evaluate the diffusive flux of aqueous methane considering non-Fickian diffusion and predict the existence of extensive bubble mass accumulation zones within deep-water sediments. The limitation on the hydrate deposit capacity is revealed; too weak deposits cannot reach the base of the hydrate stability zone and form any bubbly horizon.

The contribution of genes required for anaerobic respiration to the virulence of Salmonella enterica serovar Gallinarum for chickens.

Salmonella enterica serovar Gallinarum (SG) is an intracellular pathogen of chickens. To survive, to invade and to multiply in the intestinal tract and intracellularly it depends on its ability to produce energy in anaerobic conditions. The fumarate reductase (frdABCD), dimethyl sulfoxide (DMSO)-trimethylamine N-oxide (TMAO) reductase (dmsABC), and nitrate reductase (narGHIJ) operons in Salmonella Typhimurium (STM) encode enzymes involved in anaerobic respiration to the electron acceptors fumarate, DMSO, TMAO, and nitrate, respectively. They are regulated in response to nitrate and oxygen availability and changes in cell growth rate. In this study mortality rates of chickens challenged with mutants of Salmonella Gallinarum, which were defective in utilising anaerobic electron acceptors, were assessed in comparison to group of bird challenged with wild strain. The greatest degree of attenuation was observed with mutations affecting nitrate reductase (napA, narG) with additional attenuations induced by a mutation affecting fumarate reductase (frdA) and a double mutant (dmsA torC) affecting DMSO and TMAO reductase.

Altered expression of zinc transporters-4 and -6 in mild cognitive impairment, early and late Alzheimer's disease brain.

Accumulating evidence suggests that a disruption of zinc (Zn) homeostasis may play a role in the pathogenesis of Alzheimer's disease. Although several Zn transporter proteins responsible for the regulation of Zn balance are present in the brain, there has been little study of these proteins in Alzheimer's disease. To determine if alterations of Zn transporter proteins exist, levels of Zn transporter-4, which functions to remove Zn from the cytoplasm to endosomal/lysosomal compartments, and Zn transporter-6, which allocates cytoplasmic Zn to the trans-Golgi network, were measured in the hippocampus/parahippocampal gyrus, superior and middle temporal gyrus, and cerebellum of subjects with mild cognitive impairment, early Alzheimer's disease, late stage Alzheimer's disease, and age-matched controls using Western blot analysis and protein specific antibodies. Our results show that Zn transporter-4 and Zn transporter-6 are significantly (P<0.05) increased in hippocampus/parahippocampal gyrus of early Alzheimer's disease and Alzheimer's disease subjects. Zn transporter-6 is also increased (P<0.1) in the superior and middle temporal gyrus of Alzheimer's disease brain.

4-Hydroxynonenal disrupts zinc export in primary rat cortical cells.

Accumulating evidence implicates oxidative stress in the pathogenesis of several neurodegenerative disorders including Alzheimer's disease (AD). Increased lipid peroxidation, decreased levels of polyunsaturated fatty acids, and increased levels of 4-hydroxynonenal (HNE) have been demonstrated in AD brain. Proteins responsible for zinc export are localized on the plasma membrane and may be vulnerable to damage from lipid peroxidation. To test this hypothesis, cultured primary rat cortical neurons were incubated with (65)Zn for 1h and then treated with HNE (0-35 microM) for 4 h. Levels of (65)Zn in aliquots of medium were measured at 1, 2, 4h following treatment with HNE and intracellular (65)Zn measured after 4h using liquid scintillation counting. The amount of (65)Zn in medium did not differ significantly. However, a statistically significant (p<0.05) increase of (65)Zn was observed inside cortical neurons after treatment with 20 microM HNE for 4 hours. These data suggest that HNE may impair a protein essential for zinc export leading to increased levels of intracellular zinc.

Fusion of PAX7 to FKHR by the variant t(1;13)(p36;q14) translocation in alveolar rhabdomyosarcoma.

Although the t(2;13)(q35;q14) translocation has been found in most cases of the pediatric cancer alveolar rhabdomyosarcoma, several cases have been reported with a variant t(1;13)(p36;q14) translocation. Our findings indicate that this t(1;13) rearranges PAX7 on chromosome 1 and fuses it to FKHR on chromosome 13. This fusion results in a chimeric transcript consisting of 5' PAX7 and 3' FKHR regions, which is similar to the 5' PAX3-3' FKHR transcript formed by the t(2;13). The 5' PAX3 and PAX7 regions encode related DNA binding domains, and therefore we postulate that these translocations create similar chimeric transcription factors that alter expression of a common group of target genes.

Human ovarian tumors express gamma-glutamyl transpeptidase.

Gamma-glutamyl transpeptidase (GGT) is a cell surface enzyme that initiates the cleavage of extracellular glutathione, thereby providing the cell with the amino acids necessary for increased synthesis of glutathione. GGT is induced in ovarian tumor cell lines selected in vitro for resistance to cisplatin. No study has examined GGT expression in primary human ovarian tumors. We analyzed frozen sections of 80 normal human ovaries and 56 ovarian tumors for expression of GGT. Histochemical staining showed that GGT was not expressed in the cells of the follicle or surface germinal epithelium of the normal ovary. GGT was expressed in some epithelial inclusion glands and occasionally in a small subset of stromal cells. Granulosa-stromal cell tumors were largely GGT-negative. In contrast, GGT-positive neoplastic cells were observed in 33 of 45 common epithelial ovarian tumors. None of the patients had been treated with chemotherapy. Some of the tumors had only rare GGT-positive cells, while others consisted almost entirely of GGT-positive cells. Among the low malignant potential and invasive tumors, at least one-half of the cells were GGT-positive in 6 of 9 serous borderline tumors (2 with mucinous foci), 0 of 1 borderline mucinous tumor, 3 of 12 serous papillary carcinomas, 2 of 3 mucinous carcinomas, 1 of 2 endometrioid carcinomas, 2 of 2 clear cell carcinomas, 0 of 2 transitional cell carcinomas, and 4 of 5 undifferentiated carcinomas. There was no correlation between the stage of the tumor and GGT expression, indicating that a GGT-negative tumor does not become GGT-positive as it progresses to a more widely disseminated lesion. In addition, there was no correlation between serum levels of CA 125 and GGT expression. These data show that GGT is expressed in many common ovarian epithelial neoplasms. We are currently following the response of these patients to chemotherapy to determine if expression of GGT serves as a marker for identifying neoplasms with enhanced resistance to platinum-based therapy.

Alterations in zinc transporter protein-1 (ZnT-1) in the brain of subjects with mild cognitive impairment, early, and late-stage Alzheimer's disease.

Several studies show increased levels of zinc (Zn) in the Alzheimer's disease (AD) brain. More recently, alterations in synaptic Zn and Zn transporter proteins (ZnT) have been implicated in the accumulation of amyloid plaques in an animal model of AD. To determine if alterations in ZnT proteins are present in AD brain, we measured levels of ZnT-1, the protein responsible for export of Zn to the extracellular space in the amygdala (AMY), hippocampus/parahippocampal gyrus (HPG), superior and middle temporal gyrus (SMTG), inferior parietal lobule (IPL), and cerebellum (CER) of 19 AD and 14 age-matched control subjects. To determine if alterations of ZnT-1 occur early in the progression of AD, we analyzed protein levels in the HPG, SMTG and CER of 5 subjects with mild cognitive impairment (MCI), 5 subjects with early AD (EAD) and 4 appropriately age-matched controls. Western blot and dot-blot analysis showed statistically significant (p 0.05) elevations of ZnT-1 in AD AMY, HPG, and IPL and significantly depleted ZnT-1 in AD SMTG compared to age-matched control subjects. We also observed statistically significant elevations of ZnT-1 in the HPG of EAD subjects compared with controls. In contrast to late-stage AD subjects, ZnT-1 levels were significantly decreased in HPG of subjects with MCI and were significantly elevated in the SMTG of both MCI and EAD subjects compared with age-matched controls. Correlation analysis of ZnT-1 levels and senile plaque (SP) and neurofibrillary tangle (NFT) counts in the AMY and CA1 and subiculum of AD HPG showed a significant (p 0.05) positive correlation with SP counts and a trend towards a significant (p = 0.12) positive correlation with NFT counts in AMY. Overall, our results show alterations in one of the key proteins responsible for maintenance of Zn homeostasis early in the progression of AD suggesting that alterations in Zn balance could be involved in the pathogenesis of neuron degeneration and amyloid deposition in AD.

Lineage alteration in precursor B cell acute lymphoblastic leukemia following T cell lymphoblastic lymphoma.

A 10-year-old girl was diagnosed with lymphoblastic lymphoma; staging evaluation revealed a large mediastinal mass and normal peripheral blood and bone marrow morphology. Tumor cell immunologic marker analysis and Southern blot gene rearrangement studies demonstrated a T-cell lineage. She achieved a complete remission following multi-agent chemotherapy; however, 19 months following initial diagnosis while on maintenance therapy, she presented with typical acute lymphoblastic leukemia (ALL). The bone marrow was replaced by lymphoblasts, though the mediastinum was normal and there was no peripheral lymphadenopathy. Repeat immunophenotypic and genotypic studies demonstrated a precursor B-cell ALL lineage without expression of the T-cell surface antigens present on the original neoplasm. Repeat genotypic analysis showed immunoglobulin heavy and light chain gene rearrangements without the T-cell receptor gamma and beta gene rearrangements noted in the original lymphoblastic lymphoma. The complete alteration of lineage in these lymphoblastic processes suggests the de novo occurrence of a second neoplasm or, alternatively, an ALL relapse from a lineage-uncommitted neoplastic lymphoid progenitor cell.

Longitudinal functional alterations in asymptomatic women at risk for Alzheimer's disease.

PURPOSE: The authors sought to determine whether known alterations of brain function in normal individuals who are at high risk for Alzheimer's disease (AD) worsen or stay the same after a significant interval of time. METHODS: The authors used functional magnetic resonance imaging (fMRI) to observe cortical activation during confrontation naming in 14 women with high AD risk and 10 with low risk, based on family history and apolipoprotein-E4 allele status. They repeated the identical scan protocol in the same patients after 4 years. RESULTS: fMRI activation in high-AD-risk participants was found to be further diverged from that of their low-AD-risk counterparts over this period. CONCLUSION: fMRI may report on the presence and progression of neuropathology in the ventral temporal cortex or in functionally connected regions in presymptomatic AD.

Stability of nuclear segments in human neutrophils and evidence against a role for microfilaments or microtubules in their genesis during differentiation of HL60 myelocytes.

The nucleus of the mature human neutrophil is segmented into three to five interconnected lobes. The physiological purpose of this segmentation is unknown, as is the mechanism by which the lobes are formed during differentiation. Using video observation of migrating human neutrophils simultaneously illuminated for fluorescence and phase-contrast microscopy, we analyzed nuclear movements with respect to cell shape changes. The number of nuclear lobes and their relative size remained constant during observation (up to 1 h). The thin connecting segments between the lobes elongated and attenuated extensively but never separated. Electron microscopic analysis of neutrophil nuclei revealed no specialized nuclear or cytoplasmic structures in the vicinity of connecting segments. With fluorescence in situ hybridization of whole chromosome probes, we determined that chromosomes are randomly distributed among neutrophil nuclear lobes. HL60 cells are a human myelocytic line that, with retinoic acid treatment, segment their nuclei and differentiate into neutrophil-like cells over several days. Using a rapidly responding variant line termed HL60/S4 (Cancer Res. 52, 949-954), we found that segmentation could be induced within 24 h. We tested the role of cytoskeletal elements in the process of nuclear segmentation. Neither the microtubule inhibitor nocodazole nor the microfilament inhibitor cytochalasin D prevented nuclear segmentation. Together, our studies suggest that nuclear lobes in neutrophils are relatively stable structures that are not generated by microtubule- or microfilament-dependent forces.

Laser microprobe mass spectrometric study of aluminum and silicon in brain emboli related to cardiac surgery.

Recent investigations have shown numerous fatty microemboli, which we previously termed small capillary and arteriolar dilatations (SCADs), in brain microvessels of patients who died after cardiac surgery assisted by cardiopulmonary bypass (CPB). The hypothesis of this study was that extraneous trace elements such as aluminum (Al) and silicon (Si) might be contaminating the blood and causing the formation of SCADs or coating the SCADs already formed in the extracorporeal circulation during CPB. Small capillary and arteriolar dilatations were identified in thick celloidin sections of the brains of 8 patients who died after cardiac surgery supported with a membrane oxygenator, and of 2 dogs that underwent CPB with a bubble oxygenator. The sections were infiltrated with Spurr's embedding medium for electron microscopy. Resin sections 0.5 microm thick were placed on 100-mesh copper grids and analyzed with laser microprobe mass spectrometry. Brain sections without SCADs from 3 patients (controls) whose deaths were not related to cardiac surgery were processed similarly. In SCADs and nearby neuropil sites of the 8 patients who had cardiac surgery, both Al and Si values were higher than in the neuropil, including vessels of the 3 controls. Si values were also high in the 2 dogs, in which a bubble oxygenator was used. Our results indicate that contamination with Al and Si continues to occur during cardiac surgery assisted by CPB. Our data also suggest that switching to membrane oxygenators from bubble oxygenators for CPB may have reduced Si contamination of blood. Further refinements of CPB aimed at eliminating microemboli formation and Al and Si entry into the circulation are warranted.

4-Hydroxynonenal, a product of lipid peroxidation, damages cholinergic neurons and impairs visuospatial memory in rats.

The mechanisms that underlie cholinergic neuronal degeneration in Alzheimer disease (AD) are unclear, but recent data suggest that oxidative stress plays a role. We report that 4-hydroxynonenal (HNE), an aldehydic product of lipid peroxidation, damages and kills basal forebrain cholinergic neurons when administered intraparenchymally. Examination of Nissl-stained brain sections following unilateral HNE infusion revealed widespread neuronal loss in basal forebrain ipsilateral to the injection, but not on the contralateral side. Levels of choline acetyltransferase activity and immunoreactivity in the ipsilateral basal forebrain and hippocampus were significantly reduced by 60-80% seven days following HNE administration. Performance in Morris water maze tasks of visuospatial memory was severely impaired in a dose-dependent manner seven days following bilateral administration of HNE. Bilateral infusion of FeCl2 (an inducer of membrane lipid peroxidation) into the basal forebrain caused neuron loss and decreased choline acetyltransferease immunoreactivity and deficits in visuospatial memory. Additionally, FeCl2 infusion increased HNE immunoreactivity, implicating HNE in iron-induced oxidative damage. Because recent studies have demonstrated HNE adducts in degenerating neurons in AD brain, the present findings suggest a role for HNE in damage to cholinergic neurons in AD.

Four-hydroxynonenal, a product of lipid peroxidation, is increased in the brain in Alzheimer's disease.

Recent studies have implicated increased oxidative stress in the pathogenesis of Alzheimer's disease (AD). Increased lipid peroxidation and decreased polyunsaturated fatty acid levels have been described in the brain in AD. Four-hydroxynonenal (HNE), an aldehyde product of lipid peroxidation, has been demonstrated to be a neurotoxin in tissue culture and in vivo studies and is elevated in ventricular fluid in AD. We report here an increase in mean free HNE in multiple brain regions in AD compared with age-matched control subjects. These increases reached statistical significance in the amygdala and hippocampus and parahippocampal gyrus, regions showing the most pronounced histopathological alterations in AD. This study, in conjunction with cell culture studies, suggests that HNE may be an important substance in the pathogenesis of neuron degeneration in AD.

Acrolein is increased in Alzheimer's disease brain and is toxic to primary hippocampal cultures.

Accumulating evidence implicates oxidative stress in the pathogenesis of several neurodegenerative diseases including Alzheimer's disease (AD). Increased lipid peroxidation, decreased levels of polyunsaturated fatty acids, and increased levels of 4-hydroxynonenal (HNE), F(2)-isoprostanes, and F(4)-neuroprostanes are present in the brain in AD. Acrolein, an alpha,beta-unsaturated aldehydic product of lipid peroxidation, is approximately 100 times more reactive than HNE and recently was demonstrated in neurofibrillary tangles in the brain in AD. In three brain regions of 10 AD patients compared with 8 age-matched control subjects, we found increased mean extractable acrolein, with the increases reaching statistical significance in the amygdala and hippocampus/parahippocampal gyrus. In hippocampal neuron cultures, acrolein was neurotoxic in a time- and concentration-dependent manner and more toxic than HNE at 5 microM concentrations of each. Acrolein exposure led to a significant concentration-dependent increase in intracellular calcium concentrations. Collectively, these data show that acrolein is increased in the brain in AD and demonstrate neurotoxicity mechanisms that might be important in the pathogenesis of neuron degeneration in AD.

Elevated 4-hydroxynonenal in ventricular fluid in Alzheimer's disease.

4-Hydroxynonenal (4-HNE), an aldehyde by-product of the peroxidation of fatty acids, has been shown to have toxic properties for neurons in culture. In light of increasing evidence that oxidative stress contributes to the neurodegenerative process in Alzheimer's disease (AD), we quantified levels of free and protein-bound 4-HNE in the ventricular fluid from 19 AD subjects and 13 control subjects by high-pressure liquid chromatography and dot-blot immunoassay. Free 4-HNE levels were found to be significantly elevated in the ventricular fluid of AD subjects compared with control subjects (p = 0.0096). These results demonstrate increased lipid peroxidation in AD brain and suggest a role for 4-HNE in the neurodegenerative process.

Glutathione transferase protects neuronal cultures against four hydroxynonenal toxicity.

Peroxidation of polyunsaturated fatty acids (PUFA), particularly arachidonic acid, leads to the generation of reactive aldehydes, including 4-hydroxynonenal (HNE). Recent studies have demonstrated an increase in lipid peroxidation, a decline in PUFA, as well as an increase in HNE, and a decrease in glutathione transferase (GST) in the brain in Alzheimer's disease. Four-hydroxynonenal is toxic to cultured neurons and to the brain of experimental animals. Although glutathione (GSH) has been shown to offer protection against HNE, no enzymatic system has been described which serves to detoxify these reactive species in neuronal cultures. Here, we describe the use of GST in the protection of neuronal cultures against HNE toxicity. Glutathione transferases are a superfamily of enzymes functioning to catalyze the nucleophilic attack of GSH on electrophilic groups on a second substrate. These enzymes function efficiently with 4-hydroxyalkenals, particularly HNE, as substrates. To investigate the protective effects of GST against HNE, primary hippocampal cultures were pretreated with GST before exposure to toxic doses of HNE which led to a statistically significant enhancement in cell survival. Pretreatment of cultures with equivalent levels of heat inactivated GST or antibody against GST did not offer protection against HNE. Control cultures pretreated with GST also demonstrated enhanced survival compared with control cells receiving no pretreatment. These data suggest that GST may be an important source of protection against the toxic effects of HNE.

Survival of hippocampal and cortical neurons in a mixture of MEM+ and B27-supplemented neurobasal medium.

Serum-free B-27 supplemented neurobasal (NB) and a 10% fetal bovine serum-supplemented Eagle's minimum essential medium (MEM+) are used to culture rat embryonic hippocampal neurons for different purposes. Although NB medium leads to enhanced cell survival, it contains biological antioxidants and is not suitable for the study of free radical damage and oxidation in cultured neurons. MEM+ without additional antioxidants has been used widely in the study of free radical damage and oxidation, although it does not support optimum neuronal survival in culture. Serum in MEM+ leads to enhanced cell survival but also promotes glial cell proliferation. In this study, we used a new combination medium (NM-2) that consists of both NB and MEM+ for growing primary hippocampal and cortical neuronal cultures. NM-2 enhanced neuronal survival 78.9% for dissociated neurons at a density of 50 cells/mm(2) and 83.1% for 100 cells/mm(2), while decreasing glial cell proliferation to 2-3% and completely inhibiting oligodendrocytes. The NM-2 minimized the effectiveness of antioxidants in the medium to the neurotoxin 4-hydroxynonenal. It also decreased neuronal clumping and provided a more even distribution of neurons. Neurons survived for 4 weeks in NM-2 without changing the original medium. NM-2 provides a good environment for studies of free radical damage and oxidation of neurons. The combination incorporates the best of both NB and MEM+ that results in high neuron survival rate, low glial cell proliferation, reduced antioxidant level, and provides relatively pure cultures of hippocampal and cortical neurons.

Acrolein, a product of lipid peroxidation, inhibits glucose and glutamate uptake in primary neuronal cultures.

Oxidative stress has been implicated in the pathogenesis of several neurodegenerative disorders including Alzheimer's disease (AD). Increased lipid peroxidation, decreased levels of polyunsaturated fatty acids, and increased levels of 4-hydroxynonenal (HNE), F(2)-isoprostanes, and F(4)-neuroprostanes are present in the brain in patients with AD. Acrolein, an alpha,beta-unsaturated aldehydic product of lipid peroxidation has been demonstrated to be approximately 100 times more reactive than HNE and is present in neurofibrillary tangles in the brain in AD. We recently demonstrated statistically significant elevated concentrations of extractable acrolein in the hippocampus/parahippocampal gyrus and amygdala in AD compared with age-matched control subjects. Concentrations of acrolein were two to five times those of HNE in the same samples. Treatment of hippocampal cultures with acrolein led to a time- and concentration-dependent decrease in cell survival as well as a concentration-dependent increase in intracellular calcium. In cortical neuron cultures, we now report that acrolein causes a concentration-dependent impairment of glutamate uptake and glucose transport in cortical neuron cultures. Treatment of cortical astrocyte cultures with acrolein led to the same pattern of impairment of glutamate uptake as observed in cortical neuron cultures. Collectively, these data demonstrate neurotoxicity mechanisms of arolein that might be important in the pathogenesis of neuron degeneration in AD.

Decreased thioredoxin and increased thioredoxin reductase levels in Alzheimer's disease brain.

Increasing evidence supports the role of reactive oxygen species (ROS) in the pathogenesis of Alzheimer's disease (AD). Both in vivo and in vitro studies demonstrate that thioredoxin (Trx) and thioredoxin reductase (TR), the enzyme responsible for reduction of oxidized Trx, have protective roles against cytotoxicity mediated by the generation of ROS. The present study measured levels of Trx protein and activities of TR in the brain in AD compared with control subjects, and evaluated the possible protective role of TR and Trx against amyloid beta-peptide (Abeta) toxicity in neuronal cultures. Analysis of Trx protein levels in 10 AD and 10 control subjects demonstrated a general decrease in all AD brain regions studied, with statistically significant decreases in the amygdala (p <.05), hippocampus/parahippocampal gyrus (p <.05), and marginally significant (p <.10) depletions in the superior and middle temporal gryi. Thioredoxin reductase activity levels were increased in all AD brain regions studied with statistically significant increases occurring in AD amygdala (p =.01) and cerebellum (p =.007). To investigate the protective effects of Trx and TR against Abeta-induced toxicity, primary hippocampal cultures were treated with Trx or TR in combination with toxic doses of Abeta. Treatment of cultures with Trx led to a statistically significant concentration-dependent enhancement in cell survival against Abeta-mediated toxicity as did treatment with TR. Together, these data suggest that, although TR is protective against Abeta-mediated toxicity, the increase observed in AD brain offers no protection due to the significant decrease in Trx levels. This decrease in the antioxidant Trx-TR system may contribute to the increased oxidative stress and subsequent neurodegeneration observed in the brain in AD.

Expression of glutathione-S-transferase isozyme in the SY5Y neuroblastoma cell line increases resistance to oxidative stress.

Glutathione-S-transferases (GSTs) are a superfamily of enzymes that function to catalyze the nucleophilic attack of glutathione on electrophilic groups of a second substrate. GSTs are present in many organs and have been implicated in the detoxification of endogenous alpha, beta unsaturated aldehydes, including 4-hydroxynonenal (HNE). Exogenous GST protects hippocampal neurons against HNE in culture. To test the hypothesis that overexpression of GST in cells would increase resistance to exogenous or endogenous HNE induced by oxidative stress, stable transfectants of SY5Y neuroblastoma cells with GST were established. Stable GST transfectants demonstrated enzyme activities 13.7 times (Clone 1) and 30 times (Clone 2) higher than cells transfected with vector alone. GST transfectants (both Clones 1 and 2) demonstrated significantly (p <.05) increased resistance to ferrous sulfate/hydrogen peroxide (20.9% for Clone 1; 46.5% for Clone 2), amyloid beta-peptide (12.2% for Clone 1; 27.5.% for Clone 2), and peroxynitrite (24.3% for Clone 1; 43.9% for Clone 2), but not to exogenous application of HNE in culture medium. GST transfectants treated with 1,1,4-tris (acetyloxy)nonane, a nontoxic derivative of HNE that is degraded to HNE intracellularly, demonstrated a statistically significant (p <.05) increase in viability in a dose-dependent manner compared with SY5Y cells transfected with vector alone. These results suggest that overexpression of GST increases resistance to endogenous HNE induced by oxidative stress or released in the degradation of 1,1,4-tris (acetyloxy)nonane, but not to exogenous application of HNE.