Researchers at the University of Toronto, led by biochemist Frederick Banting, prove that the hormone insulin regulates blood sugar.
Insulin (, from Latin insula, 'island') is a peptide hormone produced by beta cells of the pancreatic islets encoded in humans by the INS gene. 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.
Beta cells are sensitive to blood sugar levels so that they secrete insulin into the blood in response to high level of glucose, and inhibit secretion of insulin when glucose levels are low. Insulin enhances glucose uptake and metabolism in the cells, thereby reducing blood sugar level. Their neighboring alpha cells, by taking their cues from the beta cells, secrete glucagon into the blood in the opposite manner: increased secretion when blood glucose is low, and decreased secretion when glucose concentrations are high. Glucagon increases blood glucose level by stimulating glycogenolysis and gluconeogenesis in the liver. The secretion of insulin and glucagon into the blood in response to the blood glucose concentration is the primary mechanism of glucose homeostasis.Decreased or absent insulin activity results in diabetes mellitus, a condition of high blood sugar level (hyperglycaemia). There are two types of the disease. In diabetes mellitus type 1, the beta cells are destroyed by an autoimmune reaction so that insulin can no longer be synthesized or be secreted into the blood. In diabetes mellitus type 2, the destruction of beta cells is less pronounced than in type 1, and is not due to an autoimmune process. Instead, there is an accumulation of amyloid in the pancreatic islets, which likely disrupts their anatomy and physiology. The pathogenesis of type 2 diabetes is not well understood but reduced population of islet beta-cells, reduced secretory function of islet beta-cells that survive, and peripheral tissue insulin resistance are known to be involved. Type 2 diabetes is characterized by increased glucagon secretion which is unaffected by, and unresponsive to the concentration of blood glucose. But insulin is still secreted into the blood in response to the blood glucose. As a result, glucose accumulates in the blood.
The human insulin protein is composed of 51 amino acids, and has a molecular mass of 5808 Da. It is a heterodimer of an A-chain and a B-chain, which are linked together by disulfide bonds. Insulin's structure varies slightly between species of animals. Insulin from animal sources differs somewhat in effectiveness (in carbohydrate metabolism effects) from human insulin because of these variations. Porcine insulin is especially close to the human version, and was widely used to treat type 1 diabetics before human insulin could be produced in large quantities by recombinant DNA technologies.Insulin was the first peptide hormone discovered. Frederick Banting and Charles Herbert Best, working in the laboratory of J. J. R. Macleod at the University of Toronto, were the first to isolate insulin from dog pancreas in 1921. Frederick Sanger sequenced the amino acid structure in 1951, which made insulin the first protein to be fully sequenced. The crystal structure of insulin in the solid state was determined by Dorothy Hodgkin in 1969. Insulin is also the first protein to be chemically synthesised and produced by DNA recombinant technology. It is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system.
The University of Toronto (U of T or UToronto), known more specifically as the University of Toronto St. George, is a public research university in Toronto, Ontario, Canada, located on the grounds that surround Queen's Park. It was founded by royal charter in 1827 as King's College, the first institution of higher learning in Upper Canada. Originally controlled by the Church of England, the university assumed its present name in 1850 upon becoming a secular institution. As a collegiate university, it comprises eleven colleges each with substantial autonomy on financial and institutional affairs and significant differences in character and history. The St. George campus is one of the three campuses that make up the University of Toronto tri-campus system, the other two of which are suburban campuses located in Scarborough and Mississauga.
The University of Toronto offers over 700 undergraduate and 200 graduate programs. In all major rankings, the university consistently ranks in the top ten public universities in the world and as the top university in the country. It receives the most annual scientific research funding and endowment of any Canadian university and is one of two members of the Association of American Universities outside the United States, the other being McGill University in Montreal.Academically, the University of Toronto is noted for influential movements and curricula in literary criticism and communication theory, known collectively as the Toronto School. The university was the birthplace of insulin and stem cell research, the first artificial cardiac pacemaker, and the site of the first successful lung transplant and nerve transplant. The university was also home to the first electron microscope, the development of deep learning, neural network, multi-touch technology, the identification of the first black hole Cygnus X-1, and the development of the theory of NP-completeness.
The Varsity Blues are the athletic teams that represent the university in intercollegiate league matches, primarily within U Sports, with ties to gridiron football, rowing and ice hockey. The earliest recorded instance of gridiron football occurred at University of Toronto's University College in November 1861. The university's Hart House is an early example of the North American student centre, simultaneously serving cultural, intellectual, and recreational interests within its large Gothic-revival complex.
The University of Toronto alumni include three Governors General of Canada, five Prime Ministers of Canada, nine foreign leaders, and seventeen justices of the Supreme Court of Canada. As of March 2019, twelve Nobel laureates, six Turing Award winners, 94 Rhodes Scholars, and one Fields Medalist have been affiliated with the university.