Brain edema and the consequent increase in intracranial pressure and brain herniation are major complications of acute liver failure (fulminant hepatic failure) and a major cause of death in this condition. Ammonia has been strongly implicated as an important factor, and astrocyte swelling appears to be primarily responsible for the edema. Ammonia is known to cause cell swelling in cultured astrocytes, although the means by which this occurs has not been fully elucidated. A disturbance in one or more of these systems may result in loss of ion homeostasis and cell swelling. In particular, activation of the Na-K-Cl cotransporter (NKCC1) has been shown to be involved in cell swelling in several neurological disorders. We therefore examined the effect of ammonia on NKCC activity and its potential role in the swelling of astrocytes. Cultured astrocytes were exposed to ammonia (NH 4 Cl; 5 mM), and NKCC activity was measured. Ammonia increased NKCC activity at 24 h. Inhibition of this activity by bumetanide diminished ammonia-induced astrocyte swelling. Ammonia also increased total as well as phosphorylated NKCC1. Treatment with cyclohexamide, a potent inhibitor of protein synthesis, diminished NKCC1 protein expression and NKCC activity. Since ammonia is known to induce oxidative/ nitrosative stress, and antioxidants and nitric-oxide synthase inhibition diminish astrocyte swelling, we also examined whether ammonia caused oxidation and/or nitration of NKCC1. Cultures exposed to ammonia increased the state of oxidation and nitration of NKCC1, whereas the antioxidants N-nitro-L-arginine methyl ester and uric acid all significantly diminished NKCC activity. These agents also reduced phosphorylated NKCC1 expression. These results suggest that activation of NKCC1 is an important factor in the mediation of astrocyte swelling by ammonia and that such activation appears to be mediated by NKCC1 abundance as well as by its oxidation/nitration and phosphorylation.

This study was undertaken to determine potential tissue sources of plasma cholesteryl ester transfer protein (CETP), and to assess the influence of CETP on lipoprotein concentrations and atherosclerosis. In a group of 28 cynomolgus monkeys fed high fat, high cholesterol diets, plasma CETP concentration was strongly correlated with the abundance of CETP mRNA in liver and in adipose tissue, and with the output of CETP in liver perfusates. Plasma CETP concentration showed a strong inverse correlation with HDL cholesterol concentrations (r = -0.62, P < 0.001) and a positive correlation with LDL cholesterol concentration (r = 0.54, P < 0.005) and molecular weight (r = 0.57, P < 0.001). The extent ofcoronary artery atherosclerosis was positively correlated with LDL cholesterol concentration and molecular weight, and with plasma CETP concentration. Thus, in monkeys fed an atherogenic diet, individual variation in CETP mRNA abundance in liver and adipose tissue probably plays a major role in the determination of plasma CETP levels. In plasma, CETP influences the distribution of cholesteryl esters between LDL and HDL, and CETP concentration appears to be a key determinant of the relative atherogenicity of the plasma lipoproteins. (J. Clin. Invest.

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In the majority of Ewing's family tumors, chromosomal translocation t(11;22) leads to aberrant fusion of RNAbinding protein EWS with DNA-binding ETS transcriptional factor Fli-1. EWS-Fli-1 has altered the transcriptional activity and modulating its downstream target genes through this transcriptional activity is thought to be responsible for this tumor. We have previously shown that both EWS-Fli-1 and Fli-1 have antiapoptotic activity against several apoptotic inducers. Here, we show that the transcriptional activity of EWS-Fli-1 and Fli-1 is not essential for its antiapoptotic activity. We also demonstrate that EWS-Fli-1 and Fli-1 interact with CBP through its amino-terminal region and inhibit the CBPdependent transcriptional activity of RXR. This activity appears to be independent of DNA-binding activity of EWS-Fli-1. Introduction of the dominant-negative form of CBP into Ewing's sarcoma cells sensitizes these cells against genotoxic or retinoic-acid induced apoptosis. These results suggest that the ability of EWS-Fli-1/Fli-1 to target transcriptional cofactor(s) and modulate apoptotic pathways may be responsible for its antiapoptotic and tumorigenic activities.

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Hyperglycemia and acidosis are the hallmarks of diabetes. Since these factors play an important role in diabetic complications, we have studied the brain catecholamine levels in hyperglycemic and acidotic conditions per se, Experimentally induced hyperglycemia and acidosis are accompanied by significant alterations in the catecholamine levels in discrete areas of the brain. We and others have shown that chronic or acute diabetes in animals, as well as in humans results in altered neurotransmitter levels. In the present study, hyperglycemia maintained by daily external administration of glucose for thirty days showed increased level of dopamine in striatum and hippocampus, elevation of norepinephrine in hippocampus, and increased level of epinephrine in hypothalamus, midbrain and pons medulla. The ammonium chloride induced acidosis demonstrated significant elevation of dopamine in midbrain and significant increase of norepinephrine in hypothalamus and midbrain, and increased level of epinephrine in hypothalamus, pons medulla and cerebral cortex. On the other hand, sodium acetoacetate induced acidosis did not show any significant change in the level of catecholamines in any of the areas studied. In conclusion, the changes in catecholamine levels observed in experimentally induced hyperglycemic as well as in acidotic conditions are closely related to the changes observed in spontaneous or alloxan or streptozotocin diabetic animals, thereby suggesting that these conditions may be responsible for the changes observed in diabetic animals.Hyperglycemia and acidosis are the key factors which lead to diabetic complications through multifaceted events. Chronic diabetes is associated with characteristic functional and structural abnormalities in the eyes, kidneys, nerves and arteries, which become clinically apparent only after many years of disease (1,2). Acute administration of glucose suppresses the discharge rate of dopamine-containing substantia nigra neurons in chloral hydrate anesthetized rats (3). Glucose also activates tyrosine hydroxylase in rat striatal synaptosomes (4), which would tend to increase the rate of dopamine synthesis and release. On the other hand, the infusion of epinephrine induces reduction in glucose disposal (5). There are several other reports suggesting that not only a turnover rate, but also a steady state level of monoamines may be altered in diabetes (6,7).Numerous studies have shown that the experimentally induced diabetes in animal models have demonstrated abnormalities in noradrenergic as well as dopaminergic systems, including the turnover rate (8,9), density of receptors (10,11) and other functions that depend on norepinephrine (NA) or dopamine (DA) systems (12)(13)(14). Catecholamines and hormones are important organizers of the brain, especially during the development of neuroendocirne systems (15,16).