Insulin cells

Diabetes results from a lack of insulin secretion by the pancreas. Without insulin, cells take up glucose very slowly. The lack of insulin results in an inability to use blood glucose for fuel. Consequently, the body behaves as if it were starving even though food is available. The metabolic responses of the untreated insulin-dependent diabetic are essentially the metabolic responses of starvation. 

MiiLLER, G. and Frick, W. Signalling via caveolin involvement in the cross-talk between phosphoinositolglycans and insulin. Cell Mol. Lfe Sci., 1999, 56, 945-970. 

Most of the cells in the human body contain a complete set of instructions (within the DNA in the nucleus) to make— not just the proteins needed by that particular cell— but all of the proteins needed by the human body. However, any one cell does not s)mthesize every protein specified by the genes of its DNA. Cells synthesize only tiiose proteins that are important to their function. For example, pancreatic cells synthesize insulin and therefore use the insulin gene within their nucleus for the instructions. Pancreatic cells do not, however, synthesize keratin (hair protein), even though the keratin gene is also contained within their nucleus. The cells in the scalp, on the other hand (which also have both insulin and keratin genes in their nuclei), synthesize keratin but not insulin. Cells synthesize only the proteins that are specific to their function. 

Hogan, B. L. M., Mcllhinney, A., and Murden, S., 1974, Effect of growth conditions on the activity of ornithine decarboxylase in cultured hepatoma cells. II. Effect of serum and insulin, /. Cell Physiol. 83 353. 

Insulin and Amylin. Insulin is a member of a family of related peptides, the insulin-like growth factors (IGFs), including IGF-I and IGF-II (60) and amylin (75), a 37-amino acid peptide that mimics the secretory pattern of insulin. Amylin is deficient ia type 1 diabetes meUitus but is elevated ia hyperinsulinemic states such as insulin resistance, mild glucose iatolerance, and hypertension (33). Insulin is synthesized ia pancreatic P cells from proinsulin, giving rise to the two peptide chains, 4. and B, of the insulin molecule. IGF-I and IGF-II have stmctures that are homologous to that of proinsulin (see INSULIN AND OTHER ANTIDIABETIC DRUGS). 

Biological reactors play a valuable role in tlie conversion of substrates by microorganisms and mammalian cells into a wide range of products such as antibiotics, insulin, and polymers. Figures 11-12, 11-13, and 11-14 illustrate various types of biological reactor, and Figure 11-15 shows the physical characteristics of a typical coimuercial fermentation vessel. 

Hepoxylins are metabolites of arachidonic acid which arise from 12-HPETE in tissues such as pancreatic islet cells (where they stimulate glucose-dependent insulin release) and brain (where they appear to have a neuromodulatory role). The structure of the hepoxylins was confirmed by synthesis which also has provided this scarce material for biological investigation. 

T24.Dyhukt, J. M., Ankarcrona, M., Burkitt, M.,. Sjbholm,. 4.,. Strom, K., Orrenius, S., and Nico-tera, P. (1994). Different prooxidant levels stimulate grownh, trigger apoptosis, or produce necrosis of insulin-secreting RINm5F cells./. Biol. Chem. 269, 30553-30560. 

Insulin is composed of two peptide chains covalently linked by disulfide bonds (Figures 5.17 and 6.35). This monomer of insulin is the active form that binds to receptors in target cells. However, in solution, insulin spontaneously forms dimers, which themselves aggregate to form hexamers. The surface of the insulin molecule that self-associates to form hexamers is also the surface that binds to insulin receptors in target cells. Thus, hexamers of insulin are inactive. 

Recombinant DNA technology now verges on the ability to engineer at will the genetic constitution of organisms for desired ends. The commercial production of therapeutic biomolecules in microbial cultures is already established (for example, the production of human insulin in quantity in E. coli cells). Agricultural crops with desired attributes, such as enhanced resistance to her-... 

The primary hormone responsible for conversion of glucose to glycogen is insulin (Figure 6.36). Insulin is secreted by special cells in the pancreas called the islets of Langerhans. Secretion of insulin is a response to increased glucose in the... 

Bradykinin stimulates natriuresis and, through stimulation of prostaglandin synthesis, inhibits the actions of antidiuretic hormone (ADH), thereby inhibiting water retention. Bradykinin further improves insulin sensitivity and cellular glucose utilization of skeletal muscle cells in experimental models. This, however, appears not to be relevant in the clinical context. 

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