Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the subcommissural organ (SCO) of the guinea pig, rat, golden hamster, and mouse the activity and distribution of enzymes related to the energy-supplying metabolism and of some marker enzymes of different cell organelles have been investigated by means of mostly modified histochemical methods. The results were compared with findings in the ciliated ependyma of the ventricular wall and with those in the ependyma of the choroid plexus of the third ventricle. In the ependymal part of the SCO only a moderate activity of hexokinase is observed in its specialized columnar cells whereas a high activity is present both in the ciliated ependyma and the choroid plexus. - The staining pattern of glucose-6-phosphatase is similar to that of hexokinase but this enzyme is found is the SCO only. - Likewise hexokinase, glycogen granules and enzymes related to glycogen metabolism (phosphoglucomutase, uridine-diphosphoglucose pyrophosphorylase, glycogen synthetase and phosphorylase) are regularly found most numerous and active in the nuclear and supra-nuclear area of the ependymal part. These enzymes are less active in both the other ependymal regions. - Uridine-diphosphoglucose dehydrogenase could not be demonstrated in the SCO. The NADP-linked enzymes of the pentose phosphate shunt, glucose-6-phosphate and 6-phosphogluconate dehydrogenase, show a moderate activity which decreases also from the nuclear towards the apical area of the ependymal cells of the SCO. Enzymes of the glycolytic pathway, such as glucosephosphate isomerase, fructose-6-phosphate kinase, fructose-I,6-diphosphate aldolase, glyceraldehyde-3-phosphate and lactate dehydrogenase, are highly active in the SCO and are located mainly in the supranuclear area, too. Fructose-1,6-diphosphatase could not be demonstrated thus indicating that in the SCO the pathway is most probably only glycolytic but not gluconeogenetic. Compared to the ependyma of the ventricular wall and of the choroid plexus, in the SCO the M type subunits of lactate dehydrogenase predominate. Glycolytic enzymes are also very active in the choroid plexus but less in the ciliated ependyma. Compared to the ciliated ependyma and especially to the ependyma of the choroid plexus, the activities of enzymes which are only present in mitochondria (NAD-linked isocitrate dehydrogenase, succinate dehydrogenase, NAD-linked malate dehydrogenase after preextraction, cytochrome oxidase, 3-hydroxybutyrate and glycerolphosphate and glutamate dehydrogenase) are relatively low. Mitochondria are accumulated near the superior pole of the nuclei as well as in the most apical part of the ependymal cells. - The staining pattern of NADP-linked isocitrate and malate dehydrogenase as well as of NADH dehydrogenase suggests that these enzymes are localized both in and out of mitochondria. The extramitochondrial activity of the first two enzymes might be localized in the cytosol. The extramitochondrial activity of NADH dehydrogenase might be localized in the endoplasmic reticulum...
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PMID:Enzymatic organization of the subcommissural organ. 123 49

The effects of various glycolytic substrates and keto acid metabolites on the cytotoxic effects of cyanide have been studied with isolated rat hepatocytes. The sequence of cytotoxic events with 2 mM cyanide was an immediate inhibition of respiration followed by ATP depletion. Disruption of the plasma membrane occurred when 85-90% of ATP levels had been depleted. Fructose, dihydroxyacetone, glyceraldehyde, pyruvate, and alpha-ketoglutarate prevented cyanide-induced cytotoxicity and ATP depletion. Hepatocyte respiration was also restored by all except fructose. Fructose, unlike the others, also did not prevent cytotoxicity if added 30-60 min after cyanide. Fluoride, an inhibitor of the glycolytic enzyme enolase, prevented protection by fructose but not dihydroxyacetone or glyceraldehyde, suggesting that dihydroxyacetone and glyceraldehyde are cytoprotective by trapping cyanide, thereby restoring cytochrome oxidase activity and cellular ATP levels. Fructose, on the other hand, may be cytoprotective by supplying ATP through glycolysis. Hepatocytes isolated from fasted rats were five- to sevenfold more susceptible to cyanide-induced cytotoxicity. Furthermore, all glycogenic and gluconeogenic amino acids and carbohydrates were cytoprotective against cyanide toxicity toward fasted hepatocytes, suggesting that cellular energy stores determine their resistance to cyanide.
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PMID:Prevention of cyanide-induced cytotoxicity by nutrients in isolated rat hepatocytes. 794 May 42