Prognostic factors and rational approach in the treatment of submucosal cancer of the stomach

Metallothionein (MT) mRNA levels were analyzed following exposure of neonatal rat primary astrocyte cultures to physiologic pH (7.4), acidosis (pH 6.5 and 6.0), and dimethyl sulfoxide (DMSO). Treatments were carried out both in the presence and absence of the bioflavonoid, quercetin. Total RNA was probed on northern blots with [alpha32P]dCTP-labeled synthetic cDNA probes specific for rat MT isoform mRNAs. MT-I and MT-II mRNA levels in astrocytes exposed to pH 6.5 or pH 6.0 were increased compared to controls (pH 7.4). Treatment with DMSO in the presence and absence of acidosis, also increased MT-I and MT-II mRNA levels compared to controls (pH 7.4). The DMSO-induced increase in MT mRNA expression was reversed by treatment of astrocytes with quercetin, such that MT-I and MT-II mRNA levels in DMSO plus quercetin-treated astrocytes were indistinguishable from mRNA levels in their respective controls at pH 7.4, pH 6.5, and pH 6.0. These findings suggest that both acidosis and DMSO exposure are associated with increased astrocytic MT synthesis at the mRNA level, and that quercetin, effectively blocks MT mRNA induction by DMSO.     

Osmotic stress in viable Escherichia coli as the basis for the antibiotic response by polymyxin B

Cationic antimicrobial peptides, such as polymyxin B (PxB), below growth inhibitory concentration induce expression of osmY gene in viable E. coli without leakage of solutes and protons. osmY expression is also a locus of hyperosmotic stress response induced by common food preservatives, such as hypertonic NaCl or sucrose. High selectivity of PxB against Gram-negative organisms and the basis for the hyperosmotic stress response at sublethal PxB concentrations is attributed to PxB-induced mixing of anionic phospholipid between the outer layer of the cytoplasmic membrane with phospholipids in the inner layer of the outer membrane. This explanation is supported by PxB-mediated rapid and direct exchange of anionic phospholipid between vesicles. This mechanism is consistent with the observation that genetically stable resistance against PxB could not be induced by mutagenesis.     

RU-486 blocks stress-induced enhancement of proenkephalin gene expression in the paraventricular nucleus of rat hypothalamus

The purpose of this study was to investigate the glucocorticoid (GC) mediated regulation of corticotropin-releasing hormone (CRH) and proenkephalin (PE) gene expressions in the paraventricular nucleus (PVN) of the hypothalamus during physical stress induced by a single intraperitoneal (i.p.) injection of hypertonic saline (9% NaCl). Previous intracerebroventricular (i.c.v.) administration of the type II glucocorticoid receptor (GR) antagonist RU-486 (20 ng/rat), increased the basal CRH mRNA levels in the PVN but had no effect on PE gene expression. Stress induced by injection of hypertonic saline increased both CRH and PE mRNA levels in PVN. Administration of RU-486 completely blocked the stress-induced increase of PE mRNA levels, but failed to alter the CRH mRNA levels in the PNV. These data suggests that, under these experimental conditions, endogenous GC are necessary for a normal PE response to hypertonic saline stress.     

Localization of metallothionein-I and -III expression in the CNS of transgenic mice with astrocyte-targeted expression of interleukin 6

The effect of interleukin-6 (IL-6) on metallothionein-I (MT-I) and MT-III expression in the brain has been studied in transgenic mice expressing IL-6 under the regulatory control of the glial fibrillary acidic protein gene promoter (GFAP-IL6 mice), which develop chronic progressive neurodegenerative disease. In situ hybridization analysis revealed that GFAP-IL6 (G16-low expressor line, and G36-high expressor line) mice had strongly increased MT-I mRNA levels in the cerebellum (Purkinje and granular layers of the cerebellar cortex and basal nuclei) and, to a lesser degree, in thalamus (only G36 line) and hypothalamus, whereas no significant alterations were observed in other brain areas studied. Microautoradiography and immunocytochemistry studies suggest that the MT-I expression is predominantly localized to astrocytes throughout the cerebrum and especially in Bergman glia in the cerebellum. However, a significant expression was also observed in microglia of the GFAP-IL6 mice. MT-III expression was significantly increased in the Purkinje cell layer and basal nuclei of the cerebellum, which was confirmed by Northern blot analysis of poly(A)+ mRNA and by ELISA of the MT-III protein. In contrast, in the G36 but not G16 mice, transgene expression of IL-6 was associated with significantly decreased MT-III RNA levels in the dentate gyrus and CA3 pyramidal neuron layer of the hippocampus and, in both G36 and G16 mice, in the occipital but not frontal cortex and in ependymal cells. Thus, both the widely expressed MT-I isoform and the CNS specific MT-III isoform are significantly affected in a MT isoform- and CNS area-specific manner in the GFAP-IL6 mice, a chronic model of brain damage.     

Expression and functional role of the Id HLH family in cultured astrocytes

The Id family of helix-loop-helix factors (Id1, Id2, and Id3) expressed in many types of cells has been reported to negatively regulate myoblast differentiation and is required for G1/S progression of arrested fibroblasts. Our previous studies have indicated that Id1, Id2, and Id3 mRNA expression appear in the subventricular zone of 1-day-old rat brains. At later ages, Id3 mRNA was only expressed in astrocytes. We now report that Id1 and Id3 mRNA expression increased in astrocytes during the first hour of serum stimulation. Subsequently, the Id1 and Id3 mRNA levels gradually declined to basal level as observed in cultures without serum stimulation. However, there was no significant difference in Id2 mRNA expression between serum-treated and control astrocyte cultures within 1 h of serum induction. In addition, a strong nuclear immunostaining for Id2 and Id3 proteins was observed 24 h after serum stimulation. This observation is consistent with our results that show an increase in Id2 and Id3 protein levels following 24 h serum induction. Furthermore, DNA synthesis in FCS-stimulated astrocytes was blocked by antisense oligonucleotides against Id3 mRNA. The addition of Id3 antisense oligonucleotides caused approximately 50% reduction in Id3 mRNA and protein levels when compared to that in sense-treated cultures. The results indicate that the inhibition of DNA synthesis in FCS-stimulated astrocytes is due to a decrease in Id3 levels by the antisense. These observations suggest that Id3 may play an important role in the regulation of astrocyte proliferation.     

Expression of type II nitric oxide synthase in primary human astrocytes and microglia: role of IL-1beta and IL-1 receptor antagonist

In this work, we studied the expression of type II nitric oxide synthase (NOS) in primary cultures of human astrocytes and microglia. Cytokine-activated human fetal astrocytes expressed a 4.5-kb type II NOS mRNA that was first evident at 8 h, steadily increased through 48 h, and persisted through 72 h. The inducing signals for astrocyte NOS II mRNA expression were in the order IL-1beta + IFN-gamma > IL-1beta + TNF-alpha > IL-1beta. SDS-PAGE analysis of cytokine-stimulated astrocyte cultures revealed an approximately 130-kDa single NOS II band that was expressed strongly at 48 and 72 h (72 h > 48 h). Specific NOS II immunoreactivity was detected in cytokine-treated astrocytes, both in the cytosol and in a discrete paranuclear region, which corresponded to Golgi-like membranes on immunoelectron microscopy. In human microglia, cytokines and LPS failed to induce NOS II expression, while the same stimuli readily induced TNF-alpha expression. In cytokine-treated human astrocytes, neither NOS II mRNA/protein expression nor nitrite production was inhibited by TGF-beta, IL-4, or IL-10. In contrast, IL-1 receptor antagonist exerted near complete inhibition of NOS II mRNA and nitrite induction. Monocyte chemoattractant peptide-1 mRNA was induced in TGF-beta-treated astrocytes, demonstrating the presence of receptors for TGF-beta in astrocytes. These results confirm that in humans, cytokines stimulate astrocytes, but not microglia, to express NOS II belonging to the high output nitric oxide system similar to that found in rodent macrophages. They also show that the regulation of type II NOS expression in human glia differs significantly from that in rodent glia. A crucial role for the IL-1 pathway in the regulation of human astrocyte NOS II is shown, suggesting a potential role for IL-1 as a regulator of astrocyte activation in vivo.     

Fourier analysis of nucleotide sequences. Periodicity in E. coli promoter sequences

The synthesis of proinflammatory cytokines involves members of the mitogen-activated protein (MAP) kinase stress pathway, particularly p38 MAP kinase and c-jun NH2-terminal kinase. In this report we used hyperosmotic stress to study changes in steady-state mRNA levels and synthesis of proinflammatory cytokines in freshly obtained human peripheral blood mononuclear cells (PBMC) in vitro. There was no evidence of interleukin (IL)-8 gene expression in freshly obtained human blood despite 30 cycles of amplification of reverse-transcribed mRNA using the polymerase chain reaction. In contrast, exposure of PBMC to hyperosmotic conditions (330-410 mOsM) by the addition of NaCl to tissue culture medium induced gene expression for IL-1 alpha, IL-1 beta, and IL-8. Routine tissue culture medium is hyperosmotic (305 mOsM) compared to human plasma (280-295 mOsM), but decreasing the osmolarity to the physiological range resulted in a 50% reduction in baseline IL-8 synthesis (P < 0.001). Although hyperosmotically induced accumulation of steady-state mRNA levels for IL-1 alpha and IL-1 beta increased 50- and 7-fold over control, respectively, these were poorly translated into each respective cytokine. However, in PBMC stimulated by hyperosmotic stress, the addition of femtomolar concentrations of bacterial lipopolysaccharide, IL-1, or 1% normal human serum resulted in a synergistic synthesis (at least twice that expected) of IL-1 alpha, IL-1 beta, TNF-alpha, and IL-8.     

Effect of increasing doses of hypertonic saline on mucociliary clearance in patients with cystic fibrosis

BACKGROUND: Patients with cystic fibrosis are known to have decreased mucociliary clearance. It has previously been shown that inhalation of a 7.0% solution of hypertonic saline significantly improved mucociliary clearance in a group of adult patients with cystic fibrosis. The aim of this study was to measure the response to increasing concentrations of inhaled hypertonic saline. METHODS: Ten patients (seven men) of mean (SE) age 22 (4) years and mean forced expiratory volume in one second (FEV1) 52.0 (6.7)% predicted completed the study. Mucociliary clearance was measured using a radioaerosol technique for 90 minutes after the interventions which comprised 0.9% NaCl + voluntary cough (control), 3.0% NaCl, 7.0% NaCl, and 12% NaCl. RESULTS: There was a significant increase in the amount of activity cleared from the right lung with all concentrations of hypertonic saline (HS) compared with control. The amount cleared at 90 minutes on the control day was 12.7% (95% confidence interval (CI) 9.8 to 17.2) compared with 19.7% (95% CI 13.6 to 29.5) for 3% HS, 23.8% (95% CI 15.9 to 36.7) for 7% HS and 26.0% (95% CI 19.8 to 35.9) for 12% HS. The improvement in mucociliary clearance was not solely due to coughing as the number of coughs recorded on the control day exceeded that recorded on any other day. The hypertonic saline did not induce a clinically significant change in FEV1. CONCLUSIONS: Within the range of concentrations examined in this study, the effect of hypertonic saline appears to be dose dependent. Inhalation of hypertonic saline remains a potentially useful treatment for patients with cystic fibrosis.     

Hypertonic saline dextran prime reduces increased intracranial pressure during cardiopulmonary bypass in pigs

Children and adults who develop neurologic deficits after cardiac surgery may experience cerebral ischemia during cardiopulmonary bypass. Increased intracranial pressure (ICP) may contribute to cerebral ischemia during bypass. Hypertonic saline dextran (HSD), a hyperosmotic, hyperoncotic resuscitation solution, decreases ICP in trauma resuscitation. We hypothesized that HSD would decrease ICP, reduce brain water, and reduce intravascular fluid requirements during bypass. Twelve swine were divided into two bypass groups: Group 1 (ISO = isotonic) received as prime 1 L of lactated Ringer's solution and 500 mL of 6% hydroxyethyl starch. Group 2 (HSD = hypertonic saline/dextran) received as prime 1 L of lactated Ringer's solution, 500 mL of 6% hydroxyethyl starch, and 1 mL/kg of 24% hypertonic saline/25% dextran. Normothermic bypass was instituted at 100 mL.kg-1.min-1. ICP increased significantly during bypass with ISO prime but not with HSD. Brain water in the cerebrum did not differ between groups but was reduced in the cerebellum to 75.9% +/- 1.4%. We conclude that HSD prevented any significant increase in ICP during normothermic bypass, and substantially improved fluid balance during bypass. In cardiac surgery patients in whom maintaining decreased ICP and reducing isotonic fluid administration is important, HSD may be a useful addition to the bypass prime solution.     

Hemophagocytic syndrome: an underestimated cause of the syndrome of non-infectious fever?]

The effects of two ethanol doses (2 and 3 g/kg) on colonic temperature and levels of norepinephrine (NE) and uncoupling protein (UCP) mRNA in the interscapular brown adipose tissue (IBAT) were examined in rats exposed to 20 degrees C or 4 degrees C for 2 h. The controls received 0.9% NaCl solution. Ethanol produced a significant hypothermic effect versus saline at both temperature conditions. The dose at 3 g/kg reduced colonic temperature more in the cold than at room temperature (p < 0.01), whereas the ambient temperature did not affect the decrease in rats that received ethanol 2 g/kg. At room temperature ethanol did not significantly change the levels of NE or UCP mRNA, whereas after cold exposure (4 degrees C) NE levels in the ethanol-treated rats were significantly lower than in the controls (p < 0.001). Ethanol did not prevent a cold-induced increase in the UCP mRNA levels, although it reduced an increase. The magnitude of the reduction in increase was dependent on the dose, being significant at the dose of 3 g/kg (p < 0.05). The results show that the ethanol-induced drop in body temperature is not necessarily related to IBAT thermogenesis, as indicated by the levels of NE and UCP mRNA.     

Self-administered intravenous infusion of hypertonic solutions and sodium appetite of sheep.

Studied the effects of self-administered iv infusion of hypertonic NaCl, mannitol, glucose, urea, or isotonic NaCl on Na appetite. 22 Merino-Cross sheep were trained to barpress to replace Na deficits of 300–500 mmol. During basal conditions, each delivery to a drinking cup was 15 ml of .6 M NaHCO? (9 mmol). In the experimental situation, an iv infusion was given automatically with each delivery to the drinking cup. Ingestion of NaHCO? solution was significantly reduced by all hypertonic solutions, the largest decrease being caused by hypertonic NaCl or mannitol. The decreased intake was observed within 10 (with infusion of hypertonic NaCl, mannitol, or glucose) or 20–40 (with urea infusion) minutes, irrespective of whether water was concurrently available to drink. At 20 min, plasma Na was increased by hypertonic NaCl, decreased by mannitol or glucose, and not changed by urea. CSF Na concentration was increased by all hypertonic solutions. In regard to the "turn-off" of Na appetite by systemic infusion, data are consistent with the theory of neural cells within the blood–brain barrier responsive to changes of Na concentration or osmolality in their environment. In contrast, water intake was stimulated by hypertonic NaCl or mannitol but not by urea or glucose. Results suggest that the sensors involved in thirst (e.g., osmoreceptors) are in an area of the brain lacking the blood–brain barrier. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Regulation of the glial Na+-dependent glutamate transporters by cyclic AMP analogs and neurons

Sodium-dependent transport into astrocytes is critical for maintaining the extracellular concentrations of glutamate below toxic levels in the central nervous system. In this study, the expression of the glial glutamate transporters GLT-1 and GLAST was studied in primary cultures derived from cortical tissue. In primary astrocytes, GLAST protein levels were approximately one half of those observed in cortical tissue, but GLT-1 protein was present at very low levels compared with cortical tissue. Maintenance of these astrocytes in medium supplemented with dibutyryl-cAMP (dbcAMP) caused a dramatic change in cell morphology, increased GLT-1 and GLAST mRNA levels approximately 5-fold, increased GLAST protein approximately 2-fold, and increased GLT-1 protein >/=8-20-fold. These increases in protein expression were accompanied by 2-fold increases in the Vmax and Km values for Na+-dependent L-[3H]glutamate transport activity. Although GLT-1 is sensitive to inhibition by dihydrokainate in heterologous expression systems, no dihydrokainate sensitivity was observed in astrocyte cultures that expressed GLT-1. Biotinylation with a membrane-impermeant reagent, separation of the biotinylated/cell surface proteins, and subsequent Western blotting demonstrated that both GLT-1 and GLAST were present at the cell surface. Coculturing of astrocytes with neurons also induced expression of GLT-1, which colocalized with the glial specific marker, glial fibrillary acidic protein. Neurons induced a small increase in GLAST protein. Several studies were performed to examine the mechanism by which neurons regulate expression of the glial transporters. Three different protein kinase A (PKA) antagonists did not block the effect of neurons on glial expression of GLT-1 protein, but the addition of dbcAMP to mixed cultures of neurons and astrocytes did not cause GLT-1 protein to increase further. This suggests that neurons do not regulate GLT-1 by activation of PKA but that neurons and dbcAMP regulate GLT-1 protein through convergent pathways. As was observed with GLT-1, the increases in GLAST protein observed in cocultures were not blocked by PKA antagonists, but unlike GLT-1, the addition of dbcAMP to mixed cultures of neurons and astrocytes caused GLAST protein to increase approximately 2-fold. Neurons separated from astrocytes with a semipermeable membrane increased GLT-1 protein, indicating that the effect of neurons was mediated by a diffusible molecule. Treatment of cocultures with high concentrations of either N-methyl-D-aspartate or glutamate killed the neurons, caused GLT-1 protein to decrease, and caused GLAST protein to increase. These studies suggest that GLT-1 and GLAST protein are regulated independently in astrocyte cultures and that a diffusible molecule secreted by neurons induces expression of GLT-1 in astrocytes.     

Common toads (Bufo arenarum) learn to anticipate and avoid hypertonic saline solutions.

Toads (Bufo arenarum) were exposed to pairings between immersion in a neutral saline solution (i.e., one that caused no significant variation in fluid balance), followed by immersion in a highly hypertonic saline solution (i.e., one that caused water loss). In Experiment 1, solutions were presented in a Pavlovian conditioning arrangement. A group receiving a single neutral-highly hypertonic pairing per day exhibited a greater conditioned increase in heart rate than groups receiving either the same solutions in an explicitly unpaired fashion, or just the neutral solution. Paired toads also showed a greater ability to compensate for water loss across trials than that of the explicitly unpaired group. Using the same reinforcers and a similar apparatus, Experiment 2 demonstrated that toads learn a one-way avoidance response motivated by immersion in the highly hypertonic solution. Cardiac and avoidance conditioning are elements of an adaptive system for confronting aversive situations involving loss of water balance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

V(H) repertoire of a marsupial (Monodelphis domestica)

We have been using a genetic strategy to define the contribution of specific candidate genes, such as those encoding subunits of the gamma-aminobutyric acid type A receptor, to various ethanol sensitive responses. We have used the gene knockout approach in mouse embryonic stem cells to create mice in which the gene encoding the alpha6 subunit of the gamma-aminobutyric acid type A receptor is rendered nonfunctional. In the present report, we provide a detailed characterization of several behavioral responses to ethanol in these null allele mice. In a separate series of experiments, behavioral response to ethanol was compared between two inbred strains of mice that are commonly used as background stock in knockout experiments, namely C57BL/6J and Strain 129/SvJ. Wild type (alpha6+/+) and homozygous null allele (alpha6-/-) mice did not differ to the ataxic effects of ethanol on acute functional tolerance (95.8 +/- 8.7 vs. 98.8 +/- 5.7 mg/dl +/- SEM, respectively). Withdrawal hyperexcitability was assessed following chronic exposure to ethanol vapor (EtOH) or air (CONT) in inhalation chambers in a multiple withdrawal treatment paradigm. At the end of the last treatment cycle, mice were scored for handling induced convulsions (HIC). After adjusting for differences in blood ethanol concentration between genotypes at the end of the final treatment cycle, we observed a greater area under the 24-hr HIC curves in mice treated with ethanol (p < 0.0001) but did not detect an effect of genotype (alpha6+/+/CONT 3.1 +/- 2.0; alpha6-/-/CONT 5.5 +/- 2.5; alpha6+/+/EtOH 30.1 +/- 6.2; alpha6-/-/EtOH 33.0 +/- 5.8 mean units +/- SEM). We also examined these mice for differences in protracted tolerance; at approximately 26 hr into the final withdrawal cycle, each mouse was injected with ethanol (3.5 mg/g body weight) and sleep time was measured. We detected a significant effect of treatment (p < 0.001) with ethanol-treated mice demonstrating signs of tolerance as reflected by a reduction in duration of sleep time. However, effect of genotype was not significant (alpha6+/+/CONT 57.4 +/- 7.6; alpha6-/-/CONT 59.0 +/- 7.6; alpha6+/ +/EtOH 34.8 +/- 7.4; alpha6-/-/EtOH 30.8 +/- 5.6 min +/- SEM). From these data we conclude that the alpha6 subunit of the GABA(A)-R exerts little if any influence on acute functional tolerance, withdrawal hyperexcitability, or protracted tolerance. Strain 129/SvJ and C57BL/6J mice were also compared for acute functional tolerance and were found not to differ (96.3 +/- 4.4 vs. 94.8 +/- 11.3 mg/dl +/- SEM, respectively). Withdrawal hyperexcitability was assessed by comparing the area under the 24 hr HIC curves. Strain 129/SvJ mice displayed a much greater basal HIC response compared to C57BL/6J mice (19.8 +/- 4.3 vs. 0.2 +/- 0.2 mean units +/- SEM, respectively); after adjusting for differences in blood ethanol concentration between strains at the end of the final ethanol treatment cycle, the HIC response was markedly enhanced by ethanol treatment in Strain 129/SvJ mice but not in C57BL/6J mice (50.4 +/- 3.1 vs. 9.5 +/- 5.4 mean units +/- SEM, respectively). The effects of treatment (p < 0.0001), strain (p < 0.0001), and the interaction of strain with treatment (p < 0.01) were significant. Since many gene knockout mice are maintained on a mixed genetic background of Strain 129/SvJ and C57BL/6J, we conclude that significant differences in tests of withdrawal hyperexcitability may be confounded by the influence of genes that cosegregate with the gene targeted allele.     

Modification of hypoxia-induced injury in cultured rat astrocytes by high levels of glucose

BACKGROUND AND PURPOSE: Preexisting hyperglycemia exacerbates central nervous system injury after transient global and focal cerebral ischemia. Increased anaerobic metabolism with resultant lactic acidosis has been shown to cause the hyperglycemic, neuronal injury. The contribution of astrocytes in producing lactic acidosis under hyperglycemic/ischemic conditions is unclear, whereas the protective role of astrocytes in ischemic-induced neuronal injury has been documented. The ability of astrocytes to maintain energy status and ion homeostasis under hyperglycemic conditions could ultimately reduce neuronal injury. Therefore, we determined the effects of increased glucose concentrations on glucose utilization, lactate production, extracellular pH, and adenosine triphosphate concentrations in hypoxia-treated astrocyte cultures. METHODS: Primary astrocytes were prepared from neonatal rat cerebral cortices. After 35 days in vitro, cultures were incubated with 0-60 mmol/L glucose and subjected to hypoxic conditions at 95% N2/5% CO2 for 24 hours. In addition, under high-glucose conditions (30 mmol/L), astrocytes were exposed to up to 72 hours of hypoxia. Determination of lactate dehydrogenase efflux, adenosine triphosphate concentrations, and extracellular lactate concentrations defined astrocyte status. Equiosmolar levels of mannitol were added in place of high glucose concentrations to distinguish hyperosmotic effect. RESULTS: When physiological concentrations of glucose (7.5 mmol/L) or lower concentrations were used, significant cell damage occurred with 24 hours of hypoxia, as determined by increased efflux of lactate dehydrogenase and loss of cell protein. When higher glucose concentrations (15-60 mmol/L) were used, efflux of lactate dehydrogenase was similar to that observed in normoxic cultures, despite an increased utilization of glucose. Lactate concentrations in the media at low or normal glucose concentrations exceeded normoxic levels, but higher glucose concentrations (15-30 mmol/L) failed to increase lactate levels further. Values of adenosine triphosphate for hypoxic astrocytes treated with high glucose concentrations were significantly higher than those of astrocytes with zero or low glucose levels. In cultures exposed to hypoxia and high glucose levels (30 mmol/L), no cellular injury was observed before 48 hours of hypoxia. Lactate concentrations in the media increased during the first 24 hours of hypoxia and reached steady state. The pH of the media decreased to 6.4 after 24 hours and 5.5 at 48 hours. The latter pH was concomitant with a marked increase in extracellular lactate dehydrogenase activity. Hyperosmotic mannitol failed to protect cultured astrocytes against hypoxia. CONCLUSIONS: Hypoxic injury to mature astrocytes was reduced by the presence of 15-60 mmol/L glucose in the medium during 24-30 hours of hypoxia. Injury occurred when the pH of the medium was < 5.5. This protection was not afforded by the hyperosmotic effect of high glucose concentrations, nor was the hypoxic injury at later time periods with 30 mmol/L glucose mediated solely by lactate accumulation.