Prospects for gene therapy of diabetes: Carbohydrate regulated extrapancreatic insulin expression in transgenic mice.
Item
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Title
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Prospects for gene therapy of diabetes: Carbohydrate regulated extrapancreatic insulin expression in transgenic mice.
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Identifier
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AAI9618094
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identifier
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9618094
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Creator
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Ripps, Michael Eliot.
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Contributor
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Adviser: Jon W. Gordon
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Date
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1996
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Genetics | Biology, Animal Physiology | Health Sciences, Pathology
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Abstract
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This thesis research focuses on the development of strategies for genetically engineering physiologically appropriate hepatic insulin production as an approach to the treatment of diabetes mellitus. Diabetes mellitus is a prevalent metabolic disorder resulting from a loss of insulin-producing pancreatic islet cells or a decrease in the peripheral response to insulin. Despite current treatment, many patients develop major complications that represent a great health burden. The benefits of intensive insulin therapy in delaying progression of the disease provide an impetus for developing improved modes of insulin delivery. The liver possesses several attributes that make it an attractive candidate for genetically engineering insulin production with regulatory properties similar to pancreatic beta cells. Hepatocytes express the glucose transporter isoform GLUT-2 and the glucose phosphorylating enzyme glucokinase, which are key components of the glucose-sensing apparatus in pancreatic beta cells. Hepatocytes also express the liver-type pyruvate kinase (L-PK) gene, which is regulated at the transcriptional level by glucose responsive elements. The L-PK gene thus represents a hepatic analog to the pancreatic-expressed insulin gene, which contains similar regulatory elements. To examine the potential for engineering physiologically appropriate hepatic insulin production, transgenic mice expressing the human insulin gene under control of the L-PK promoter were produced. Results demonstrate that insulin expression in liver, intestine, and kidney is stimulated by carbohydrate feeding. Hepatic insulin mRNA levels were induced up to 100 fold when fasted mice were refed with a high sucrose diet and there were rapid increases in the mRNA level after injection of a glucose load. Mice subjected to beta cell ablation had a partial correction of hyperglycemia, with decreases in both non-fasting and fasting blood glucose levels and without episodes of hypoglycemia. These findings indicate significant potential for L-PK:insulin constructs to provide a homeostatic control mechanism for the endogenous production of insulin that is responsive to changes in blood glucose concentration in the physiologic range. Improvements in construct design may lead to the development of gene therapy vectors suitable for the treatment of diabetes mellitus.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
