Langerhans islet cells

Krenacs, T., Laszik, Z., and DobU, E. (1989) Application of immnnogold-silver staining and immunoenzymatic methods in mnltiple labeling of hnman pancreatic Langerhans islet cells. Acta Histochem. 85, 79-85. 

In addition to the direct effects of hyperglycemia in enhancing the uptake of glucose into the liver, the hormone insulin plays a central role in regulating blood glucose. It is produced by the B cells of the islets of Langerhans in the pancreas in response to hyperglycemia. The B islet cells are freely permeable to glu-... 

Insulin and glucagon are produced in the pancreas by cells known as islets of Langerhans. P-Cells make up 70% to 90% of the islets and produce insulin, whereas P-cells produce glucagon. The main function of insulin is to decrease blood glucose levels, whereas glucagon, along with other counterregulatory... 

In the body, insulin is synthesized by j3-cells of Langerhans islets in the pancreas. The rate of formation changes depending on the type of food consnmed, gastrointestinal hormones, and nenronal control. Insnlin circnlating in the body has a biological half-life of about 5 min. It is qnickly broken down by enzymes and is removed from the blood by the liver or kidneys. 

Islets of Langerhans—Distinctive cells in the pancreas that produce insulin. 

The answer is d. (Hardman, pp 1242-1243.) Streptozocin is an alkylating agent with the capacity to cross-link DNA, thereby inhibiting its synthesis. It is a nitrosourea-like antibiotic that contains a glucosamine moiety that allows it to be selectively taken up by the p cells of the islets of Langerhans. Consequently, it can be useful in treating metastatic islet cell carcinoma. 

Animals ex pancreas islets of Langerhans a cells, targets liver... 

The first glucose sensors to be discovered were the pancreatic -cells in the islets of Langerhans these manufacture the hormone insulin and release it into the blood when glucose concentration rises. Islet tissue also contains a-cells, which manufacture the antagonistic hormone glucagon. Insulin secretion is a complex process, and the islet cells receive additional signals from the gut and the autonomic nervous system, which modulate the insulin release to match the food that has been eaten. 

Westermark P, Wernstedt C, Wilander E, Hayden DW, O Brien TD, Johnson KH. Amyloid fibrils in human insulinoma and islets of Langerhans of the diabetic cat are derived from a neuropeptide-like protein also present in normal islet cells. Proc. Natl. Acad. Sci. U.S.A. 1987 84 3881-3885. 

Exocrine secretes digestive enzymes into the duodenum endocrine has cell clusters called islets of Langerhans alpha islet cells produce glucagons beta cells secrete insulin... 

From a morphological point of view the islet of Langerhans is a complicated system since it consists of different cells, with different hormones affecting secretion from different cells, the latter also being affected by nutrients, drugs and peptides/hormones which reach the islet cells via the bloodstream. Moreover, islet cells are under the control of the autonomous nervous system. As far as their distribution is concerned, B-cells are localized in the centre whereas A- and D-cells are distributed in the mantle of the islet. 

Streptozotocin is unique both in origin and pharmacology. It is an antibiotic obtained from Streptomyces achromogenes and contains a glucosamine component in its structure, which may contribute to its tendency to be taken up into the P-cells of the islets of Langerhans of the pancreas. Where it was initially used to induce diabetes in experimental animals, it is now used to treat pancreatic islet cell carcinoma, resulting in about a 50% response rate, but few survivors past 1 year. 

To consider diabetes only as a pancreatic endocrine disease is an oversimplification. The pancreatic cells known as islets of Langerhans found throughout the gland produce at least four hormones. The largest proportion of islet cells are the beta cells that produce... 

INSULIN PRODUCTION The islet of Langerhans contains four major ceU types, each of which synthesizes and secretes a distinct polypeptide hormone insulin in the j3 (B) cell, glucagon in the a (A) cell, somatostatin in the S (D) cell, and pancreatic polypeptide in the PP or F cell. The P cells make up 60-80% of the islet and form its central core with the a, 6 and F cells in a discontinuous mantle around this core. The geographical organization of islet cells facilitates coordinated control of groups of cells. Blood in the islet flows from the j3 cells to a and S cells. Thus, the j3 cell is the primary glucose sensor for the islet, and the other cell types presumably are exposed to particularly high concentrations of insulin. 

Homeostatic Hormones. Insulin is produced by beta cells found in the islets of Langerhans that are dispersed throughout the pancreas. The islet cells constitute only 1% of total pancreatic tissue. Each islet contains about 3000 endocrine cells with a core of beta cells surrounded by other endocrine cells such as the glucagon-secreting alpha cells, the somatostatin-secreting delta cells, and the pancreatic polypeptide-secreting PP cells. The beta cells first synthesize a 109-amino-acid preproinsulin that is subsequently processed to an 86-amino-acid proinsulin. The... 

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