This is a working overview of incretin, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-10-22 and is reviewed periodically as new material appears.
Receptor activation follows the canonical Gs pathway: binding increases intracellular cyclic AMP, which promotes protein kinase A activity. In pancreatic beta cells this amplifies glucose-dependent insulin release, so secretion rises when blood glucose is high and changes little when it is low. The same signalling suppresses glucagon release from alpha cells and slows gastric emptying. Receptors in the hypothalamus and brainstem are thought to contribute to reduced appetite and lower energy intake. Which of these effects dominates clinical outcomes remains an area of active study.
Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released by intestinal L cells after food intake. The natural hormone acts on pancreatic and central receptors but is degraded within minutes by dipeptidyl peptidase-4 and other peptidases. Semaglutide belongs to the class of long-acting GLP-1 receptor agonists, a group distinguished by structural changes that slow breakdown and extend circulation time. Its development followed earlier short-acting analogues and reflects a general strategy in peptide drug design: preserve receptor activity while blocking proteolytic clearance.
Large randomised trials in adults with type 2 diabetes and in adults with obesity have reported reductions in body weight and improvements in several cardiovascular risk markers. One outcome trial found a lower incidence of major adverse cardiovascular events in participants with diabetes and established cardiovascular disease. Gastrointestinal effects such as nausea and vomiting are the most frequently reported adverse events and often diminish over time. Changes in lean body mass during weight loss are an area of ongoing investigation. Effects in adolescents and in pregnancy are less well characterised, and current labelling advises against use during pregnancy.
Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released after nutrient intake. The molecule contains 31 amino acid residues and differs from the native sequence at several positions. A non-natural residue at position eight resists the enzyme that normally truncates the hormone, while a lysine-linked fatty diacid side chain promotes binding to serum albumin. These two modifications extend the circulating half-life from minutes to roughly one week. The peptide is produced by solid-phase synthesis followed by selective acylation, and its identity and purity are confirmed by spectrometric and chromatographic techniques.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C187H291N45O59 | free base, without counter-ion |
| Molecular weight | About 4114 Da | peptide backbone plus attached lipid chain |
| Plasma half-life | About 165 hours | supports once-weekly dosing in humans |
| Plasma protein binding | Greater than 99 percent | attributed mainly to serum albumin |
| Receptor target | GLP-1 receptor | Gs-coupled, raises intracellular cyclic AMP |
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 or 280 nanometres is widely used to assess purity and to resolve related impurities. Liquid chromatography coupled to mass spectrometry confirms identity through the protonated molecular ion and fragment ions formed in tandem experiments. Capillary electrophoresis and peptide mapping after enzymatic digestion supply complementary information on charge variants and modification sites. Circular dichroism and nuclear magnetic resonance can report on secondary structure in solution. Absolute quantification usually depends on an external standard, and reported purity depends on the detection wavelength and integration parameters chosen.
Lyophilised material appears as a white to off-white cake or powder that is hygroscopic, and containers are usually equilibrated to room temperature before opening to limit condensation. Dissolution is performed in water, phosphate-buffered saline, or a mildly alkaline buffer, since solubility rises above neutral pH. Gentle inversion or low-speed mixing is preferred, because vigorous vortexing can promote surface denaturation and aggregation. Complete dissolution may require several minutes, and brief sonication is sometimes applied. Passing the solution through a 0.22 micrometre membrane removes particulates but does not by itself sterilise the liquid.
Storage at minus 20 degrees Celsius or lower in a desiccated container preserves the peptide for extended periods, while working solutions are commonly held at two to eight degrees Celsius for short intervals. Light exposure and repeated freeze-thaw cycles accelerate degradation, so dividing material into single-use aliquots is generally recommended. Adsorption to glass and plastic surfaces can lower the measured concentration of dilute solutions, particularly below one milligram per millilitre. The degradation routes most often reported for GLP-1 analogues are deamidation, methionine oxidation, and backbone hydrolysis. Relative rates under specific conditions are frequently described only for individual formulations.
Semaglutide dissolves readily in water and in aqueous buffers near neutral pH. Solubility decreases near the isoelectric point, where net charge is minimal. Common laboratory solvents include phosphate-buffered saline and dilute ammonium bicarbonate. Strongly acidic or basic conditions may accelerate hydrolysis. Working concentrations are usually prepared by diluting a concentrated stock. Vial surfaces can adsorb small amounts of peptide at low concentrations, so carrier proteins or low-binding tubes are sometimes used.
Reverse-phase high-performance liquid chromatography is the standard method for purity assessment, separating the peptide from truncated or oxidized variants. Mass spectrometry confirms molecular mass and detects modifications, while ultraviolet absorbance near 280 nanometers supports concentration measurement through tryptophan and tyrosine residues. Circular dichroism can indicate secondary structure, though the peptide is largely helical in solution, and ion-exchange chromatography resolves charge variants. Purity values above 95 percent are typical for research-grade material. Stability studies track degradation over time under defined conditions.
Lyophilized semaglutide is typically stored at temperatures between minus 20 and minus 80 degrees Celsius for long-term preservation. Short-term storage at 2 to 8 degrees Celsius is common for working aliquots. Repeated freeze-thaw cycles can degrade the peptide and are usually avoided. The molecule is hygroscopic in its solid form, so containers should remain sealed with desiccant. Solutions are less stable than powders and are generally prepared fresh. Light exposure is limited because aromatic residues can undergo photo-oxidation.
Semaglutide is a synthetic peptide that acts as an agonist at the glucagon-like peptide-1 receptor. It is a structural analogue of human GLP-1(7-37), modified to resist enzymatic degradation by dipeptidyl peptidase-4. The peptide backbone contains alpha-aminoisobutyric acid at position 8, a substitution that stabilises the helix and slows cleavage. A fatty diacid side chain attached through a linker at lysine 34 promotes binding to serum albumin, which extends the circulating half-life. These two modifications together allow less frequent administration than native GLP-1 requires.
Activation of the GLP-1 receptor couples to Gs signalling and raises intracellular cyclic AMP in pancreatic beta cells. The resulting insulin release depends on prevailing glucose concentrations, so the effect is greater when glucose is elevated. Receptor engagement also suppresses glucagon secretion and slows gastric emptying, which flattens post-meal glucose excursions. In the central nervous system, signalling in hypothalamic and brainstem regions is associated with reduced appetite and lower energy intake. Studies continue to examine effects on cardiac, renal and hepatic endpoints; whether those benefits are independent of weight change remains an open question.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1 (GLP-1), a hormone released from intestinal L-cells after food intake. The compound belongs to the incretin mimetic class and acts at GLP-1 receptors distributed across pancreatic, gastrointestinal, cardiovascular, and central nervous system tissues. Compared with native GLP-1, the molecule carries structural changes that extend its activity from minutes to roughly one week. It is studied for glycemic control in type 2 diabetes and for weight management, and its effects on cardiovascular and other outcomes remain active research areas.
Receptor binding triggers G protein signaling that raises intracellular cyclic AMP in pancreatic beta cells. Insulin release follows in a glucose-dependent manner, so secretion increases when blood glucose is elevated and diminishes when it is not. The same signaling suppresses glucagon release from alpha cells and slows gastric emptying, which blunts the post-meal glucose rise. In the brain, receptor activation in regions such as the arcuate nucleus is associated with reduced appetite and lower energy intake. How much each of these effects contributes to overall weight change is not fully settled.
Two structural features account for the prolonged half-life of semaglutide. A modified amino acid at position 8 resists cleavage by dipeptidyl peptidase-4, the enzyme that rapidly degrades native GLP-1. A fatty diacid side chain binds serum albumin, which limits renal clearance and protects the peptide from enzymatic breakdown. These modifications yield a plasma half-life of approximately one week in humans, allowing once-weekly administration. The relationship between plasma concentration and clinical effect varies between individuals, and sources of that variability are still being characterized.
Myxosortases, homologs of the type 2 CAAX prenyl protease Rce1, are analogous protein-sorting enzymes, but they are unlikely to function as transpeptidases. It is likely, instead, that the cysteine residue in the target sequence is modified by a separate enzyme, and that modification is followed by cleavage by the myxosortase, as happens with Rce1. The exact biochemistry of the overall modification is not yet known.
More than 20 nations, most notably the United Kingdom, joined the United States in invading Iraq as part of the "coalition of the willing". They launched the invasion on March 20, 2003. The Iraqi military was quickly defeated. The capital, Baghdad, fell on April 9, 2003. On May 1, Bush declared the end of major combat operations in Iraq. The initial success of U.S. operations increased his popularity, but the U.S. and allied forces faced a growing insurgency led by sectarian groups; Bush's "Mission Accomplished" speech was later criticized as premature. From 2004 until 2007, the situation in Iraq deteriorated further, with some observers arguing that there was a full-scale civil war in Iraq. Bush's policies met with criticism, including demands domestically to set a timetable to withdraw troops from Iraq. The 2006 report of the bipartisan Iraq Study Group, led by James Baker, concluded that the situation in Iraq was "grave and deteriorating". While Bush admitted there were strategic mistakes made in regard to the stability of Iraq, he maintained he would not change the overall Iraq strategy. According to Iraq Body Count, some 251,000 Iraqis have been killed in the civil war following the U.S.-led invasion, including at least 163,841 civilians. In January 2005, elections recognized by the West as free and fair were held in Iraq for the first time in 50 years. This led to the election of Jalal Talabani as president and Nouri al-Maliki as Prime Minister of Iraq. A referendum to approve a constitution in Iraq was held in October 2005, supported by most Shiites and many Kurds.
== The exploration of the molecular dominion == If we evaluate the molecular revolution within the context of biological history, it is easy to note that it is the culmination of a long process which began with the first observations through a microscope. The aim of these early researchers was to understand the functioning of living organisms by describing their organization at the microscopic level. From the end of the 18th century, the characterization of the chemical molecules which make up living beings gained increasingly greater attention, along with the birth of physiological chemistry in the 19th century, developed by the German chemist Justus von Liebig and following the birth of biochemistry at the beginning of the 20th, thanks to another German chemist Eduard Buchner. Between the molecules studied by chemists and the tiny structures visible under the optical microscope, such as the cellular nucleus or the chromosomes, there was an obscure zone, "the world of the ignored dimensions," as it was called by the chemical-physicist Wolfgang Ostwald. This world is populated by colloids, chemical compounds whose structure and properties were not well defined. The successes of molecular biology derived from the exploration of that unknown world by means of the new technologies developed by chemists and physicists: X-ray diffraction, electron microscopy, ultracentrifugation, and electrophoresis. These studies revealed the structure and function of the macromolecules.
In some cases, such as in parts of Kenya in 2006, rates of malnutrition in pregnant women were even higher than rates in children. Women in some societies are traditionally given less food than men since men are perceived to have heavier workloads. Household chores and agricultural tasks can in fact be very arduous and require additional energy and nutrients; however, physical activity, which largely determines energy requirements, is difficult to estimate.
== Variants == Chocolate agar with the addition of bacitracin becomes selective for the genus Haemophilus. Another variant of chocolate agar called Thayer–Martin agar contains an assortment of antibiotics that select for Neisseria species.
Sources: en.wikipedia.org
=== Myocardial infarction === Heart attack occurs in 1–2% of aortic dissections. Infarction is caused by the involvement of the coronary arteries, which supply the heart with oxygenated blood, in the dissection. The right coronary artery is involved more commonly than the left coronary artery. If the myocardial infarction is treated with thrombolytic therapy, the mortality increases to over 70%, mostly due to bleeding into the pericardial sac, causing cardiac tamponade.
Serum creatinine (a blood measurement) is an important indicator of kidney function, because it is an easily measured byproduct of muscle metabolism that is excreted unchanged by the kidneys. Creatinine itself is produced via a biological system involving creatine, phosphocreatine (also known as creatine phosphate), and adenosine triphosphate (ATP, the body's immediate energy supply). Creatine is synthesized primarily in the liver by methylation of glycocyamine (guanidino acetate, synthesized in the kidney from the amino acids arginine and glycine) by S-adenosyl methionine. It is then transported in the blood to other organs, muscles, and the brain, where it is phosphorylated to phosphocreatine, a high-energy compound. Creatine conversion to phosphocreatine is catalysed by creatine kinase; spontaneous formation of creatinine occurs during the reaction. Creatinine is removed from the blood chiefly by the kidneys, primarily by glomerular filtration, but also by proximal tubular secretion. Little or no tubular reabsorption of creatinine occurs. If filtration in the kidney is deficient, blood creatinine concentrations rise. Therefore, creatinine concentrations in blood and urine may be used to calculate the creatinine clearance (CrCl), which correlates approximately with the glomerular filtration rate (GFR). Blood creatinine concentrations may also be used alone to estimate the GFR (eGFR). The GFR is clinically important as a measurement of kidney function.
=== April to June: Allied discussions === Balfour met Weizmann at the Foreign Office on 22 March 1917; two days later, Weizmann described the meeting as being "the first time I had a real business talk with him". Weizmann explained at the meeting that the Zionists had a preference for a British protectorate over Palestine, as opposed to an American, French or international arrangement; Balfour agreed, but warned that "there may be difficulties with France and Italy". The French position in regard to Palestine and the wider Syria region during the lead up to the Balfour Declaration was largely dictated by the terms of the Sykes–Picot Agreement and was complicated from 23 November 1915 by increasing French awareness of the British discussions with the Sherif of Mecca. Prior to 1917, the British had led the fighting on the southern border of the Ottoman Empire alone, given their neighbouring Egyptian colony and the French preoccupation with the fighting on the Western Front that was taking place on their own soil. Italy's participation in the war, which began following the April 1915 Treaty of London, did not include involvement in the Middle Eastern sphere until the April 1917 Agreement of Saint-Jean-de-Maurienne; at this conference, Lloyd George had raised the question of a British protectorate of Palestine and the idea "had been very coldly received" by the French and the Italians. In May and June 1917, the French and Italians sent detachments to support the British as they built their reinforcements in preparation for a renewed attack on Palestine.
=== Macau === The Portuguese Macau government seldom interfered in the affairs of Chinese society, including with regard to regulations on the practice of TCM. There were a few TCM pharmacies in Macau during the colonial period. In 1994, the Portuguese Macau government published Decree-Law no. 53/94/M that officially started to regulate the TCM market. After the sovereign handover, the Macau S.A.R. government also published regulations on the practice of TCM. In 2000, Macau University of Science and Technology and Nanjing University of Traditional Chinese Medicine established the Macau College of Traditional Chinese Medicine to offer a degree course in Chinese medicine. In 2022, a new law regulating TCM, Law no. 11/2021, came into effect. The same law also repealed Decree-Law no. 53/94/M.
The official name of the country, according to the constitution adopted concurrently with the UDI in November 1965, was Rhodesia, which derives from Cecil Rhodes. This was not the case under British law, however, which considered the territory's legal name to be Southern Rhodesia, the name given to the country in 1898 during the British South Africa Company's administration of the Rhodesias, and retained by the self-governing colony of Southern Rhodesia after the end of company rule in 1923. This naming dispute dated back to October 1964, when Northern Rhodesia became independent from the UK and concurrently changed its name to Zambia. The Southern Rhodesian colonial government in Salisbury felt that in the absence of a "Northern" Rhodesia, the continued use of "Southern" was superfluous. It passed legislation to become simply Rhodesia, but the British government refused to approve this on the grounds that the country's name was defined by British legislation, so could not be altered by the colonial government. Salisbury went on using the shortened name in an official manner nevertheless, while the British government continued referring to the country as Southern Rhodesia. This situation continued throughout the UDI period.
Sources: en.wikipedia.org
=== Reconstructed set point === In healthy persons, the intra-individual variation of TSH and thyroid hormones is considerably smaller than the inter-individual variation. This results from a personal set point of thyroid homeostasis. In hypothyroidism, it is impossible to directly access the set point, but it can be reconstructed with methods of systems theory. A computerised algorithm, called Thyroid-SPOT, which is based on this mathematical theory, has been implemented in software applications. In patients undergoing thyroidectomy it could be demonstrated that this algorithm can be used to reconstruct the personal set point with sufficient precision.
==== Acne and seborrhea ==== Flutamide has been found to be effective in the treatment of acne and seborrhea in women in a number of studies. In a long-term study of 230 women with acne, 211 of whom also had seborrhea, very-low-dose flutamide alone or in combination with an oral contraceptive caused a marked decrease in acne and seborrhea after 6 months of treatment, with maximal effect by 1 year of treatment and benefits maintained in the years thereafter. In the study, 97% of the women reported satisfaction with the control of their acne with flutamide. In another study, flutamide decreased acne and seborrhea scores by 80% in only 3 months. In contrast, spironolactone decreased symptoms by only 40% in the same time period, suggesting superior effectiveness for flutamide for these indications. Flutamide has, in general, been found to reduce symptoms of acne by as much as 90% even at low doses, with several studies showing complete acne clearance.
The three substrates of this enzyme are L-cystine, reduced nicotinamide adenine dinucleotide (NADH) and a proton. Its products are L-cysteine and oxidised NAD+. This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is L-cysteine:NAD+ oxidoreductase. Other names in common use include cystine reductase (NADH), NADH-dependent cystine reductase, cystine reductase (NADH2), and NADH2:L-cystine oxidoreductase. This enzyme participates in cysteine metabolism.
The East Central Conference is a former high school athletic conference in Wisconsin. Originally founded in 1970, it was disbanded in 2001 and remained defunct until its reconstitution in 2015. It lasted for ten seasons before a second dissolution in 2025, and all members in both incarnations belonged to the Wisconsin Interscholastic Athletic Association.
Sources: en.wikipedia.org
Native GLP-1 is a short-lived peptide cleared within one to two minutes by dipeptidyl peptidase-4 and related enzymes. Semaglutide keeps the receptor-binding backbone but adds substitutions and a lipid chain. These changes block the main cleavage site and allow reversible albumin binding, extending the half-life to roughly 165 hours.
Albumin is the most abundant protein in plasma and carries molecules that bear fatty-acid chains. Binding shields the peptide from renal filtration and from peptidases, keeping a circulating reservoir. Slow release from this reservoir produces sustained receptor occupancy and supports infrequent dosing.
The insulinotropic effect is glucose-dependent, meaning secretion increases mainly when glucose is elevated. This property is often described as lowering the chance of hypoglycaemia when the compound is used alone. Other glucose-lowering agents used at the same time can still cause low blood glucose.
Native GLP-1 is degraded within minutes by dipeptidyl peptidase-4 and neutral endopeptidases. Semaglutide carries a non-natural amino acid at position eight that blocks that cleavage, and a fatty diacid side chain that binds albumin. The result is a much longer duration of action than the native hormone.