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Endocrinology is a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions known as hormones. It is also concerned with the integration of developmental events proliferation, growth, and differentiation, and the psychological or behavioral activities of metabolism, growth and development, tissue function, sleep, digestion, respiration, excretion, mood, stress, lactation, movement, reproduction, and sensory perception caused by hormones. Specializations include behavioral endocrinology and comparative endocrinology.
Insulin is a peptide hormone produced by beta cells of the pancreatic islets; it is considered to be the main anabolic hormone of the body. It regulates the metabolism of carbohydrates, fats and protein by promoting the absorption of glucose from the blood into liver, fat and skeletal muscle cells. In these tissues the absorbed glucose is converted into either glycogen via glycogenesis or fats (triglycerides) via lipogenesis, or, in the case of the liver, into both. Glucose production and secretion by the liver is strongly inhibited by high concentrations of insulin in the blood. Circulating insulin also affects the synthesis of proteins in a wide variety of tissues. It is therefore an anabolic hormone, promoting the conversion of small molecules in the blood into large molecules inside the cells. Low insulin levels in the blood have the opposite effect by promoting widespread catabolism, especially of reserve body fat.
The insulin-like growth factors (IGFs) are proteins with high sequence similarity to insulin. IGFs are part of a complex system that cells use to communicate with their physiologic environment. This complex system consists of two cell-surface receptors, two ligands, a family of seven high-affinity IGF-binding proteins, as well as associated IGFBP degrading enzymes, referred to collectively as proteases.
The pancreas is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine gland, i.e. it has both an endocrine and a digestive exocrine function. 99% of the pancreas is exocrine and 1% is endocrine. As an endocrine gland, it functions mostly to regulate blood sugar levels, secreting the hormones insulin, glucagon, somatostatin, and pancreatic polypeptide. As a part of the digestive system, it functions as an exocrine gland secreting pancreatic juice into the duodenum through the pancreatic duct. This juice contains bicarbonate, which neutralizes acid entering the duodenum from the stomach; and digestive enzymes, which break down carbohydrates, proteins, and fats in food entering the duodenum from the stomach.
Insulin resistance (IR) is a pathological condition in which cells fail to respond normally to the hormone insulin.
Glucagon is a peptide hormone, produced by alpha cells of the pancreas. It raises concentration of glucose and fatty acids in the bloodstream, and is considered to be the main catabolic hormone of the body. It is also used as a medication to treat a number of health conditions. Its effect is opposite to that of insulin, which lowers extracellular glucose. It is produced from proglucagon, encoded by the GCG gene.
The insulin receptor (IR) is a transmembrane receptor that is activated by insulin, IGF-I, IGF-II and belongs to the large class of receptor tyrosine kinase. Metabolically, the insulin receptor plays a key role in the regulation of glucose homeostasis, a functional process that under degenerate conditions may result in a range of clinical manifestations including diabetes and cancer. Insulin signalling controls access to blood glucose in body cells. When insulin falls, especially in those with high insulin sensitivity, body cells begin only to have access to lipids that do not require transport across the membrane. So, in this way, insulin is the key regulator of fat metabolism as well. Biochemically, the insulin receptor is encoded by a single gene INSR, from which alternate splicing during transcription results in either IR-A or IR-B isoforms. Downstream post-translational events of either isoform result in the formation of a proteolytically cleaved α and β subunit, which upon combination are ultimately capable of homo or hetero-dimerisation to produce the ≈320 kDa disulfide-linked transmembrane insulin receptor.
Insulin-like growth factor 1 (IGF-1), also called somatomedin C, is a hormone similar in molecular structure to insulin which plays an important role in childhood growth, and has anabolic effects in adults.
In the biological context of organisms' production of gene products, downregulation is the process by which a cell decreases the quantity of a cellular component, such as RNA or protein, in response to an external stimulus. The complementary process that involves increases of such components is called upregulation.
Gastric inhibitory polypeptide (GIP), or gastric inhibitory peptide, also known as glucose-dependent insulinotropic polypeptide, is an inhibiting hormone of the secretin family of hormones. While it is weak inhibitor of gastric acid secretion, its main role is to stimulate insulin secretion.
Zvi Laron is an Israeli paediatric endocrinologist. Born in Cernăuţi, Romania, Laron is a professor emeritus at Tel Aviv University. In 1966, he described the type of dwarfism later called Laron syndrome. His research opened the way to the treatment of many cases of growth hormone disorders. He was the first to introduce the multidisciplinary treatment for juvenile diabetes.
Streptozotocin or streptozocin (STZ) is a naturally occurring alkylating antineoplastic agent that is particularly toxic to the insulin-producing beta cells of the pancreas in mammals. It is used in medicine for treating certain cancers of the islets of Langerhans and used in medical research to produce an animal model for hyperglycemia and Alzheimer's in a large dose, as well as type 2 diabetes or type 1 diabetes with multiple low doses.
Sir Thomas Leon Blundell, is a British biochemist, structural biologist, and science administrator. He was a member of the team of Dorothy Hodgkin that solved in 1969 the first structure of a protein hormone, insulin. Blundell has made contributions to the structural biology of polypeptide hormones, growth factors, receptor activation, signal transduction, and DNA double-strand break repair, subjects important in cancer, tuberculosis, and familial diseases. He has developed software for protein modelling and understanding the effects of mutations on protein function, leading to new approaches to structure-guided and Fragment-based lead discovery. In 1999 he co-founded the oncology company Astex Therapeutics, which has moved ten drugs into clinical trials. Blundell has played central roles in restructuring British research councils and, as President of the UK Science Council, in developing professionalism in the practice of science.
The insulin-like growth factor 1 (IGF-1) receptor is a protein found on the surface of human cells. It is a transmembrane receptor that is activated by a hormone called insulin-like growth factor 1 (IGF-1) and by a related hormone called IGF-2. It belongs to the large class of tyrosine kinase receptors. This receptor mediates the effects of IGF-1, which is a polypeptide protein hormone similar in molecular structure to insulin. IGF-1 plays an important role in growth and continues to have anabolic effects in adults – meaning that it can induce hypertrophy of skeletal muscle and other target tissues. Mice lacking the IGF-1 receptor die late in development, and show a dramatic reduction in body mass. This testifies to the strong growth-promoting effect of this receptor.
Teresa S. Wiley is the author of Lights Out: Sleep, Sugar and Survival, and Sex, Lies and Menopause. She writes about women's health, particularly sleep and hormonal issues, hormone replacement therapy and bioidentical hormone replacement therapy. Wiley has developed her own version of BHRT known as the Wiley Protocol, though she has been strongly criticized for lacking the relevant credentials and potentially putting women at risk with an unproven, untested intervention that uses possibly dangerously high doses of hormones.
Laron syndrome (LS), also known as growth hormone insensitivity is an autosomal recessive disorder characterized by a lack of insulin-like growth factor 1 production in response to growth hormone. It is usually caused by inherited growth hormone receptor (GHR) mutations.
Derek LeRoith, M.D., Ph.D is an endocrinologist and Professor of Medicine and the current Chief of the Hilda and J. Lester Gabrilove, M.D. Division of Endocrinology, Diabetes and Bone Disease and Director of the Metabolism Institute of the Mount Sinai Medical Center in New York City. He is an international expert in insulin-like growth factor-1 (IGF-1).
Leonid Poretsky is a Russian-born American endocrinologist. His research interests include mechanisms of insulin action in the ovary, endocrinological aspects of AIDS, and clinical outcomes in diabetes. He has authored over 100 publications and has served on the National Institutes of Health's review committees and on the editorial boards of the Journal of Clinical Endocrinology and Metabolism and other endocrine journals.
Diabetes mellitus, commonly known as just diabetes, is a group of metabolic disorders characterized by a high blood sugar level over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased appetite. If left untreated, diabetes can cause many health complications. Acute complications can include diabetic ketoacidosis, hyperosmolar hyperglycemic state, or death. Serious long-term complications include cardiovascular disease, stroke, chronic kidney disease, foot ulcers, damage to the nerves, damage to the eyes and cognitive impairment.
Pierre De Meyts is a Belgian physician and biochemist known for his research on fine chemical and kinetic aspects of ligand-receptor interaction, subunit assembly, and specific metabolic effects of hormones typically causing receptor tyrosine kinase activation such as insulin and insulin-like growth factors (IGFs). He has also studied receptor signalling for other peptide hormones such as growth hormone and relaxin, and key pathophysiological aspects of diabetes mellitus. De Meyts held professorial posts for over three decades at several European and United States institutions and currently is an emeritus professor in the Science Faculty at the Université catholique de Louvain. While living in Denmark (1990-2010) he occupied executive research positions at Novo Nordisk. De Meyts is also known as a science cartoonist.
References
- ↑ "Report on Rasmus Institute". Archived from the original on 2011-07-25. Retrieved 2008-03-26.
- ↑ Harper Collins Bio [ permanent dead link ]
- ↑ Interview
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