Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.6.1.1 (adenylate cyclase)
 19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

As demonstrated previously, liver acini draining the blood from intraportally transplanted pancreatic islets in streptozotocin-diabetic rats are altered in various respects. The hepatocytes in these acini store glycogen and/or fat, and they show an increase in proliferation as well as in apoptotic activity. Thus, they are phenotypically similar to carcinogen-induced preneoplastic liver foci (glycogen-storing foci and sometimes also mixed cell foci). By means of catalytic enzyme histochemistry or immunohistochemistry, we investigated the activity of key enzymes of alternative pathways of carbohydrate metabolism and some additional marker enzymes (well known from studies on preneoplastic hepatic foci) in the altered liver acini surrounding the islet isografts. In addition, the expression of glucose transporter proteins 1 and 2 (GLUT-1 and GLUT-2) were investigated immunohistochemically. The activities of hexokinase, pyruvate kinase, glyceraldehyde-3-phosphate dehydrogenase, and glucose-6-phosphate dehydrogenase were increased, whereas the activities of glycogen phosphorylase, adenylate cyclase, glucose-6-phosphatase, and membrane-bound adenosine triphosphatase were decreased in the altered liver acini. The expression of GLUT-2 was also decreased. GLUT-1 and glutathione S-transferase placental form were not expressed, and the activities of glycogen synthase and gamma-glutamyl-transferase remained unchanged. All changes of the enzyme activities were in line with the well known effects of insulin and resembled alterations characteristic of preneoplastic liver foci observed in different models of hepatocarcinogenesis. It remains to be clarified in long-term experiments whether or not these foci represent preneoplastic lesions and may proceed to neoplasia.
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PMID:Altered liver acini induced in diabetic rats by portal vein islet isografts resemble preneoplastic hepatic foci in their enzymic pattern. 864 65

A number of soluble and membrane associated enzymes of glycolysis, pentose phosphate pathway and other related enzymes were measured in three different brain regions during aging. Enzymes utilizing and synthesizing peroxides were also included. Increasing levels of peroxidative products are known to accumulate in the brain with age. The membrane associated enzymes were found to be the primary focus of damage. Phosphofructokinase and glucose-6-phosphate dehydrogenase exhibited an unusual pattern when measured in whole homogenates. A progressive decrease in the synaptosomal bound hexokinase was found with increasing age. The synaptosomal phosphofructokinase (PFK) also showed a significant decrease with aging. Significant decrease in the incorporation of myoinositol into phospholipids and a loss of activity of membrane bound adenylate cyclase with age indicated that changes must be occurring in the structure of the brain and the loss of cerebral competence in the senescent brain may arise from peroxidative damage to membranes.
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PMID:Effect of aging on soluble and membrane bound enzymes in rat brain. 2050 79


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