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 2026-02-08 and is reviewed periodically as new material appears.
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。
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.
| Property | Value | Notes |
|---|---|---|
| 分子式 | C187H291N45O59 | 按主链与 C18 二酸侧链计算 |
| 分子量 | 约 4113.6 道尔顿 | 游离碱形式，随反离子略有差异 |
| 外观 | 白色至类白色冻干粉末 | 具吸湿性，需干燥保存 |
| 溶解性 | 微溶于水，易溶于碱性缓冲液 | 溶解性随 pH 升高而改善 |
| 等电点 | 约 5.4 | 影响缓冲液选择与聚集倾向 |
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.
Clinical development of this compound followed earlier short-acting GLP-1 analogues that required frequent injection. Once-weekly subcutaneous formulations entered use after 2017, and an oral formulation using a permeation enhancer later became available. The oral version pairs the peptide with sodium N-(8-[2-hydroxybenzoyl] amino) caprylate, a carrier that improves uptake across the gastric epithelium. Interest has expanded from glycaemic control into weight management and metabolic liver disease. Regulatory status and approved indications differ between countries, and the product remains subject to ongoing safety monitoring.
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.
The company that developed the compound filed it as a long-acting analogue, and it gained first approval in 2017 for type 2 diabetes. Later authorisations from several regulators extended the indication to chronic weight management, and the World Health Organization added the glucagon-like peptide-1 receptor agonist drug class to its model list of essential medicines in 2023. Production uses solid-phase peptide synthesis followed by side-chain conjugation and chromatographic purification. Supply constraints and cost differences across regions are well documented. Literature on long-term outcomes continues to grow, with many trials reporting surrogate endpoints rather than hard clinical endpoints.
Semaglutide is a synthetic peptide of thirty-one amino acids that shares roughly ninety-four percent sequence identity with human glucagon-like peptide-1. Two substitutions resist enzymatic cleavage by dipeptidyl peptidase-4, and a fatty diacid side chain attached through a linker promotes binding to serum albumin. That albumin binding slows renal clearance and extends the circulating half-life from minutes to approximately one week. The structural changes are well established in the published literature. Whether the same modifications affect receptor signalling bias in ways that matter clinically remains an open question.
Pharmacological activity arises from agonism at the glucagon-like peptide-1 receptor, a G protein-coupled receptor expressed in the pancreas, the gastrointestinal tract, and the brainstem. Receptor activation raises intracellular cyclic adenosine monophosphate and enhances insulin release in a glucose-dependent manner, an effect that diminishes when blood glucose concentration is low. Other effects include slowed gastric emptying and hypothalamic satiety signalling. These pathways are described well. Receptor desensitisation rates across tissues, relative to the endogenous hormone, are still under investigation, and reported findings differ between laboratories.
Vasquez ran for reelection in 2024 against Republican former Congresswoman Yvette Herrell in a rematch of the 2022 race. Vasquez once again defeated Herrell, this time by 11,032 votes, despite Donald Trump narrowly flipping New Mexico's 2nd district in the concurrent presidential election.
=== Antiviral properties === Peppermint has been shown to suppress viruses such as Influenza A, herpes simplex virus (HSV), and Vaccinia virus in laboratory studies. Mint extracts can also limit viral replication in HIV‑1, the most common strain of HIV.
Humankind gradually evolved from early members of the genus Homo—such as Homo habilis, who used simple stone tools—into anatomically modern humans as well as behaviourally modern humans by the Upper Paleolithic. During the end of the Paleolithic Age, specifically the Middle or Upper Paleolithic Age, humans began to produce the earliest works of art and to engage in religious or spiritual behavior such as burial and ritual. Conditions during the Paleolithic Age went through a set of glacial and interglacial periods in which the climate periodically fluctuated between warm and cool temperatures. By c. 50,000 – c. 40,000 BP, the first humans set foot in Australia. By c. 45,000 BP, humans lived at 61°N latitude in Europe. By c. 30,000 BP, Japan was reached, and by c. 27,000 BP humans were present in Siberia, above the Arctic Circle. By the end of the Upper Paleolithic Age humans had crossed Beringia and expanded throughout the Americas continents.
Instrument Landing System (ILS) - A short range radio navigation aid at airports which guides aircraft landing in low visibility conditions. It consists of multiple antennas at the end of each runway that radiate two beams of radio waves along the approach to the runway: the localizer (108 to 111.95 MHz frequency), which provides horizontal guidance, a heading line to keep the aircraft centered on the runway, and the glideslope (329.15 to 335 MHz) for vertical guidance, to keep the aircraft descending at the proper rate for a smooth touchdown at the correct point on the runway. Each aircraft has a receiver instrument and antenna which receives the beams, with an indicator to tell the pilot whether he is on the correct horizontal and vertical approach. The ILS beams are receivable for at least 15 miles, and have a radiated power of 25 watts. ILS systems at airports are being replaced by systems that use satellite navigation. Non-directional beacon (NDB) – Legacy fixed radio beacons used before the VOR system that transmit a simple signal in all directions for aircraft or ships to use for radio direction finding. Aircraft use automatic direction finder (ADF) receivers which use a directional antenna to determine the bearing to the beacon. By taking bearings on two beacons they can determine their position. NDBs use frequencies between 190 and 1750 kHz in the LF and MF bands which propagate beyond the horizon as ground waves or skywaves much farther than VOR beacons. They transmit a callsign consisting of one to 3 Morse code letters as an identifier.
== Chemistry == LGD-4033 is a nonsteroidal SARM with a pyrrolidinyl-benzonitrile core structure and is also referred to as a quinoline or quinolinone SARM. LG121071 (LGD-121071), a tricyclic quinoline, was the predecessor compound of LGD-4033. The chemical structure of LGD-4033 had not been disclosed as late as 2013. LGD-4033 has sometimes been confused with other structurally related Ligand Pharmaceuticals SARMs including LGD-2226, LGD-2941, and LGD-3303, but is a different compound from these agents. LGD-4033 is a small-molecule (molecular weight = 338.3 g/mol) and highly lipophilic (predicted log P = 3.6–3.7) compound.
Sources: en.wikipedia.org
=== Neutral phase === If the temperature variation from climatology is within 0.5 °C (0.9 °F), ENSO conditions are described as neutral. Neutral conditions are the transition between warm and cold phases of ENSO. Sea surface temperatures (by definition), tropical precipitation, and wind patterns are near average conditions during this phase. Close to half of all years are within neutral periods. During the neutral ENSO phase, other climate anomalies/patterns such as the sign of the North Atlantic Oscillation or the Pacific–North American teleconnection pattern exert more influence.
== States of buoyancy == Buoyancy is a characteristic of any object with a volume immersed in any fluid with a density in a gravitational field or undergoing acceleration. There are three possible states of buoyancy.
When the apical bud is removed, the lowered IAA concentration allows the lateral buds to grow and produce new shoots, which compete to become the lead growth. Pruning techniques such as coppicing and pollarding make use of this natural response to curtail direct plant growth and produce a desired shape, size, and/or productivity level for the plant. The principle of apical dominance is manipulated for espalier creation, hedge building, or artistic sculptures called topiary. If the SAM is removed, it stimulates growth in the lateral direction. By careful pruning, it is possible to create remarkable designs or patterns. Some fruit trees have strong apical dominance, and young trees can become "leggy", with poor side limb development. Apical dominance can be reduced in this case, or in cases where limbs are broken off by accident, by cutting off the auxin flow above side buds that one wishes to stimulate. This is often done by orchardists for young trees. Occasionally, strong apical dominance is advantageous, as in the "Ballerina" apple trees. These trees are intended to be grown in small gardens, and their strong apical dominance combined with a dwarfing rootstock gives a compact narrow tree with very short fruiting side branches.
== Types == Penicillins consist of a distinct 4-membered beta-lactam ring, in addition to a thiazolide ring and an R side chain. The main distinguishing feature between variants within this family is the R substituent. This side chain is connected to the 6-aminopenicillanic acid residue and results in variations in the antimicrobial spectrum, stability and susceptibility to beta-lactamases of each type.
Fomepizole, also known as 4-methylpyrazole, is a medication used to treat methanol and ethylene glycol poisoning. It may be used alone or together with hemodialysis. It is given by injection into a vein. Common side effects include headache, nausea, sleepiness, and unsteadiness. It is unclear if use during pregnancy causes risk to a fetus. Fomepizole works by blocking the enzyme that converts methanol and ethylene glycol to their toxic breakdown products. Fomepizole was approved for medical use in the United States in 1997. It is on the World Health Organization's List of Essential Medicines.
Sources: en.wikipedia.org
Though eligible to join the EU's Economic and Monetary Union (EMU), Danish voters in a referendum in 2000 rejected exchanging the krone for the euro. Whereas Denmark's neighbours like Norway, Sweden, Poland and the United Kingdom generally follow inflation targeting in their monetary policy, the priority of Denmark's central bank is to maintain exchange rate stability. Consequently, the central bank has no role in a domestic stabilization policy. In an international context, a relatively large proportion of the population is part of the labour force, in particular because the female participation rate is very high. 78.8% of all 15-to-64-year-olds were active in the labour market in 2017, the sixth-highest number among all OECD countries. With a 4.8% unemployment rate, unemployment is relatively low in comparison to other European countries, where the average unemployment rate is 6.7%. The labour market is traditionally characterized by a high degree of union membership rates and collective agreement coverage. Denmark invests heavily in active labor market policies and the concept of flexicurity has been important historically.
French waxing leaves a small amount of hair on either side of the labia or a strip directly above and in line with the pudendal cleft called a landing strip. Islam teaching includes Muslim hygienical jurisprudence a practice of which is the removal of pubic hair.
It is commonly suggested by scholars that the EPRDF's decision to establish a federal administrative structure along ethnic lines was a move towards reinforcing its political dominance. By dividing the country and facilitating the creation of accompanying ethnically-based parties under the government's control, the TPLF (which represented less than 10% of the country's population) could intensify its hold on power. Dissatisfied opposition parties argued that this form of federalization was not appropriate for the country. For instance, the All Amhara People's Organisation (AAPO) and the Ethiopian Democratic Union Party expressed in 2000 that they preferred a strong unitary state with representation of the country's nationalities at the core. Other groups, such as the Oromo National Congress (ONC) and the Ethiopia Democratic Party (EDP), were not opposed to the idea of establishing a federal system, arguing that it set the foundation for regional autonomy, but believed that it was a mistake for it to conducted along ethnic lines.
Succinate-Q oxidoreductase, also known as complex II or succinate dehydrogenase, is a second entry point to the electron transport chain. It is unusual because it is the only enzyme that is part of both the citric acid cycle and the electron transport chain. Complex II consists of four protein subunits and contains a bound flavin adenine dinucleotide (FAD) cofactor, iron–sulfur clusters, and a heme group that does not participate in electron transfer to coenzyme Q, but is believed to be important in decreasing production of reactive oxygen species. It oxidizes succinate to fumarate and reduces ubiquinone. As this reaction releases less energy than the oxidation of NADH, complex II does not transport protons across the membrane and does not contribute to the proton gradient.
Although Germans, Americans and Soviets experimented with small liquid-fuel rockets before World War II, launching satellites and humans into space required the development of larger ballistic missiles such as Wernher von Braun's Aggregat-4 (A-4), which became known as the Vergeltungswaffe 2 (V-2) developed by Nazi Germany to bomb the Allies in the war. After the war, both the US and USSR acquired custody of German rocket development assets which they used to leverage the development of their own missiles. Public interest in space flight was first aroused in October 1951 when the Soviet rocketry engineer Mikhail Tikhonravov published "Flight to the Moon" in the newspaper Pionerskaya pravda for young readers. He described a two-person interplanetary spaceship of the future and the industrial and technological processes required to create it. He ended the short article with a clear forecast of the future: "We do not have long to wait. We can assume that the bold dream of Konstantin Tsiolkovsky will be realized within the next 10 to 15 years." From March 1952 to April 1954, the US Collier's magazine reacted with a series of seven articles Man Will Conquer Space Soon! detailing Wernher von Braun's plans for crewed spaceflight. In March 1955, Disneyland's animated episode "Man in Space" which was broadcast on US television with an audience of about 40 million people, eventually fired the public enthusiasm for space travel and raised government interest, both in the US and USSR.
Sources: en.wikipedia.org
差别集中在三处：第 8 位残基被非天然氨基酸取代，第 34 位换成精氨酸，第 26 位增加一条脂肪酸侧链。前两处改动降低酶解速率，侧链则通过白蛋白结合延长循环时间。综合结果是半衰期从约两分钟延长到约一周。
胰岛素释放需要细胞内环腺苷酸与钙信号升高，同时依赖葡萄糖代谢产生的协同信号。血糖水平较低时协同信号不足，分泌增强有限。这一机制在降糖效果与低血糖风险之间提供了缓冲。
白蛋白结合是主要原因，它减少肾小球滤过并保护分子免受蛋白酶降解。序列修饰带来的酶解抵抗同样不可忽略，二者共同作用。脂肪链的疏水性还会影响组织分布，但其对总半衰期的贡献程度仍在研究之中。
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.