The short version of half-life fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-06-12. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Acylated GLP-1 receptor agonist | 31-residue synthetic peptide |
| Molecular formula | C187H291N45O59 | established for the free peptide |
| Appearance | White to off-white powder | as supplied before formulation |
| Solubility | Freely soluble in water | aqueous buffers near neutral pH |
| Typical storage | 2 to 8 degrees Celsius, protected from light | powder and solution forms differ in shelf life |
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.
Reported molecular weight is approximately 4113.6 daltons for the free base, and the peptide is supplied as a lyophilized powder or in buffered liquid form depending on the intended use. It is freely soluble in water when formulated with appropriate excipients, though the unconjugated peptide shows limited stability at neutral pH over long periods. Analytical characterization typically relies on reversed-phase high-performance liquid chromatography and mass spectrometry. Purity specifications for research-grade material commonly exceed ninety-five percent by area. Isotopic and impurity profiles differ between suppliers.
Two principal therapeutic variants exist under separate regulatory filings, one indicated for glycemic control in type 2 diabetes and one for chronic weight management. Both use the same active molecule; differences lie in formulation strength, titration schedule, and labeling. Regulatory agencies in the United States and European Union approved injectable forms in 2017 and 2018 respectively. An oral tablet formulation received approval later, using a carrier molecule to enhance absorption across the gastric epithelium. Labeling differs by jurisdiction and by indication.
The distinction between established facts and open questions matters here. That the peptide binds the GLP-1 receptor and stimulates insulin release in a glucose-dependent manner is well documented. How individual variability in receptor density, gastric emptying rate, and gut microbiome composition shapes response remains an active research area. Long-term outcomes beyond five years of continuous use are not yet fully characterized in published trials, and several extension studies are ongoing.
皮下注射后吸收相对缓慢，绝对生物利用度约为百分之八十九，血药浓度峰值通常出现在给药后一到三天。与白蛋白结合使清除减慢，终末半衰期约为一百六十五小时，接近一周。连续给药约四到五周后达到稳态暴露水平。表观分布容积约为每千克零点二五升，血浆蛋白结合率超过百分之九十九。代谢以蛋白水解切割和脂肪二酸侧链的 β-氧化为主，相关产物主要经尿液与粪便排出。
序列层面的改动同时解决了两个问题，即酶解稳定性与肾脏清除速度。天然 GLP-1 在循环中的半衰期仅约两分钟，主要被二肽基肽酶-4 迅速灭活。酰化侧链与白蛋白的可逆结合形成循环储库，使分子缓慢释放并持续激活受体。这种设计思路后来被广泛用于同类长效肽的开发，属于该类药物化学改造的典型范式。
Semaglutide 是一种经结构修饰的胰高血糖素样肽-1 类似物，其主链与内源性 GLP-1(7-36) 约有百分之九十四的序列一致性。第 8 位丙氨酸被 α-氨基异丁酸取代，使二肽基肽酶-4 无法识别原有切割位点。第 34 位赖氨酸换为精氨酸，进一步降低酶解速率。第 26 位赖氨酸经间隔基连接一条含十八个碳的二酸脂肪链，该侧链赋予分子与血浆白蛋白结合的能力。
Studies seem to indicate that ethylene affects stem diameter and height: when stems of trees are subjected to wind, causing lateral stress, greater ethylene production occurs, resulting in thicker, sturdier tree trunks and branches. Ethylene also affects fruit ripening. Normally, when the seeds are mature, ethylene production increases and builds up within the fruit, resulting in a climacteric event just before seed dispersal. The nuclear protein Ethylene Insensitive2 (EIN2) is regulated by ethylene production, and, in turn, regulates other hormones including ABA and stress hormones. Ethylene diffusion out of plants is strongly inhibited underwater. This increases internal concentrations of the gas. In numerous aquatic and semi-aquatic species (e.g. Callitriche platycarpus, rice, and Rumex palustris), the accumulated ethylene strongly stimulates upward elongation. This response is an important mechanism for the adaptive escape from submergence that avoids asphyxiation by returning the shoot and leaves to contact with the air whilst allowing the release of entrapped ethylene. At least one species (Potamogeton pectinatus) has been found to be incapable of making ethylene while retaining a conventional morphology. This suggests ethylene is a true regulator rather than being a requirement for building a plant's basic body plan.
Otto Hahn – winner of the Enrico Fermi Award 1966 U.S Government, Department of Energy Otto Hahn on Nobelprize.org including the Nobel Lecture on 13 December 1946 From the Natural Transmutations of Uranium to Its Artificial Fission Award Ceremony Speech honoring Otto Hahn by Professor Arne Westgren, Stockholm. Otto Hahn and the Discovery of Nuclear Fission Archived 1 February 2014 at the Wayback Machine BR, 2008 Otto Hahn – Discoverer of Nuclear Fission Author: Dr. Anne Hardy (Pro-Physik, 2004) Otto Hahn (1879–1968) – The discovery of fission Visit Berlin, 2011. Otto Hahn – Discoverer of nuclear fission Otto Hahn – Founder of the Atomic Age Author: Dr Edmund Neubauer (Translation: Brigitte Hippmann) – Website of the Otto Hahn Gymnasium (OHG), 2007. Otto Hahn Award Otto Hahn Peace Medal in Gold Website of the United Nations Association of Germany (DGVN) in Berlin Otto Hahn Medal The history of the Hahn Meitner Institute (HMI) Helmholtz-Zentrum, Berlin 2011. Otto Hahn heads a delegation to Israel 1959 Website of the Max Planck Society, 2011. Biography Otto Hahn 1879–1968 Otto Hahn – A Life for Science, Humanity and Peace Archived 24 September 2015 at the Wayback Machine Hiroshima University Peace Lecture, held by Dietrich Hahn, 2 October 2013. Otto Hahn – Discoverer of nuclear fission, grandfather of the Atombomb GMX, Switzerland, 17 December 2013. Author: Marinus Brandl. Newspaper clippings about Otto Hahn in the 20th Century Press Archives of the ZBW
=== 2010–2012: Early growth === Blockchain analysts estimate that Nakamoto had mined about one million bitcoins before he disappeared in 2010 and handed the network alert key and control of the code repository over to Gavin Andresen. Andresen later became lead developer at the Bitcoin Foundation, an organization founded in September 2012 to promote bitcoin. After early "proof-of-concept" transactions, the first major users of bitcoin were black markets, such as the dark web Silk Road. During its 30 months of existence, beginning in February 2011, Silk Road exclusively accepted bitcoins as payment, transacting ₿9.9 million, worth about $214 million.
Since 2018, the health effects of consuming certain processed vegetable oils, or seed oils have been subject to misinformation in popular and social media. The trend grew in 2020 after podcaster and comedian Joe Rogan interviewed fad diet proponent Paul Saladino about the carnivore diet. Saladino made several claims about the health effects of vegetable fats. The theme of the misinformation is that seed oils are the root cause of most diseases of affluence, including heart disease, cancer, diabetes, and liver spots. These claims are not based on evidence, but have nevertheless become popular on the political right. Critics cite a specific "hateful eight" oils that constitute "seed oils": canola, corn, cottonseed, soybean, sunflower, safflower, grapeseed, and rice bran. Although critics raise concerns about processing, omega-6 fatty acids, and linoleic acid, scientific evidence finds these oils safe and beneficial, with omega-6s linked to lower cardiovascular risk and no consistent evidence of increased inflammation, cancer, or chronic disease. Claims that seed oils are harmful are not supported by clinical or epidemiological data, and some health organizations warn that reducing omega-6 intake could worsen heart health. Consumer vegetable oils are generally recognized as safe for human consumption by the United States FDA.
Sources: en.wikipedia.org
== Physical properties == Ethylene oxide is a colorless gas at 25 °C (77 °F) and is a mobile liquid at 0 °C (32 °F) – viscosity of liquid ethylene oxide at 0 °C is about 5.5 times lower than that of water. The gas has a characteristic sweet odor of ether, noticeable when its concentration in air exceeds 500 ppm. Ethylene oxide is readily soluble in water, ethanol, diethyl ether, and many organic solvents. Main thermodynamical constants are:
== Marriage and family == Dayhoff's husband was Edward S. Dayhoff, an experimental physicist who worked with magnetic resonance and with lasers. They had two daughters who are also academics, Ruth and Judith. Judith Dayhoff has a PhD in mathematical biophysics from the University of Pennsylvania and is the author of Neural network architectures: An introduction and coauthor of Neural Networks and Pattern Recognition. Ruth Dayhoff graduated summa cum laude in Mathematics from the University of Maryland and focused on Medical Informatics while doing her MD at Georgetown University School of Medicine. During medical school, she co-authored a paper and a chapter in The Atlas of Protein Sequence and Structure with her mother, describing a new way to measure how closely proteins are related. Her husband Vincent Brannigan is professor emeritus of Law and Technology at the University of Maryland School of Engineering. Ruth was a founding Fellow of the American College of Medical Informatics. She pioneered the integration of Medical Imaging and invented the Vista Imaging System. She was chosen for the National Library of Medicine's project on the 200 women Physicians who "changed the face of medicine." She serves as director of Digital Imaging in Medicine for the United States Department of Veterans Affairs.
This characterization had already been proved five years earlier by Vaynshtejn. In the solution to his problem, a similar characterization was given by Vasilyev and Senderov. If h1, h2, h3, and h4 denote the altitudes in the same four triangles (from the diagonal intersection to the sides of the quadrilateral), then the quadrilateral is tangential if and only if
Sources: en.wikipedia.org
Professors at public universities are public servants, tenured and hired through public application, with international research publications being a significant criterion. A public university professor's teaching load is usually modest and leaves time for research. As a result, public university graduate programs are the primary source of Brazilian academic research. In contrast, most private institutions are for-profit enterprises that hire teachers on an hourly basis and conduct comparatively little research; notable exceptions are a few private but non-profit universities affiliated with religious organizations, such as the Mackenzie Presbyterian University of São Paulo and the Pontifical Catholic University of Rio de Janeiro.
S-(2-hydroxyacyl)glutathione + H2O = glutathione + a 2-hydroxy carboxylate This enzyme belongs to the family of hydrolases, specifically the class of thioester lyases. It is commonly known as glyoxalase II. It participates in pyruvate metabolism.
Phase I trials, usually in healthy volunteers, determine safety and dosing. Phase II trials are used to get an initial reading of efficacy and further explore safety in small numbers of patients having the disease targeted by the NCE. Phase III trials are large, pivotal trials to determine safety and efficacy in sufficiently large numbers of patients with the targeted disease. If safety and efficacy are adequately proved, clinical testing may stop at this step and the NCE advances to the new drug application (NDA) stage. Phase IV trials are post-approval trials that are sometimes a condition attached by the FDA, also called post-market surveillance studies. The process of defining characteristics of the drug does not stop once an NCE is advanced into human clinical trials. In addition to the tests required to move a novel vaccine or antiviral drug into the clinic for the first time, manufacturers must ensure that any long-term or chronic toxicities are well-defined, including effects on systems not previously monitored (fertility, reproduction, immune system, among others). If a vaccine candidate or antiviral compound emerges from these tests with an acceptable toxicity and safety profile, and the manufacturer can further show it has the desired effect in clinical trials, then the NCE portfolio of evidence can be submitted for marketing approval in the various countries where the manufacturer plans to sell it. In the United States, this process is called a "new drug application" or NDA.
Cr(CO)6 + 2 C5H6 → Cr(C5H5)2 + 6 CO + H2 Metallocenes generally have high thermal stability. Ferrocene can be sublimed in air at over 100 °C with no decomposition; metallocenes are generally purified in the laboratory by vacuum sublimation. Industrially, sublimation is not practical so metallocenes are isolated by crystallization or produced as part of a hydrocarbon solution. For Group IV metallocenes, donor solvents like ether or THF are distinctly undesirable for polyolefin catalysis. Charge-neutral metallocenes are soluble in common organic solvents. Alkyl substitution on the metallocene increases the solubility in hydrocarbon solvents.
Sources: en.wikipedia.org
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.
The fatty diacid chain associates strongly with serum albumin, which keeps the peptide in circulation and shields it from rapid renal clearance. Bound peptide is released gradually, producing a sustained receptor signal. This mechanism also reduces the peak-to-trough variation seen with shorter-acting analogues.
The balance between peripheral receptor activation and signalling in the central nervous system is not fully resolved. The extent to which slowed gastric emptying accounts for reduced energy intake, compared with direct effects on appetite circuits, is debated. Long-term effects on lean mass and on tissues outside the gut and brain are still under study.
Long-term storage is usually at minus 20 to minus 80 degrees Celsius in a sealed, desiccated container. Working aliquots can be held briefly at 2 to 8 degrees Celsius.