This is a working overview of 长效肽设计, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-03-13 and is reviewed periodically as new material appears.
The primary target is the GLP-1 receptor, a class B G protein-coupled receptor expressed on pancreatic beta cells, in the gut, and in several brain regions. Receptor activation raises intracellular cyclic AMP, which potentiates glucose-dependent insulin secretion and lowers glucagon release when blood glucose is elevated. Signalling in the hypothalamus and brainstem is associated with reduced appetite and slower gastric emptying. Because the insulinotropic effect depends on prevailing glucose levels, the hypoglycaemic risk of the peptide alone is described as low in most study settings. The relative contribution of peripheral and central actions remains an active research question.
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.
Development began in the early 2010s with the goal of extending GLP-1 activity beyond the brief window achieved by native peptide infusion. The earliest approved formulation was a subcutaneous injection given once weekly. A later oral tablet pairs the peptide with an absorption enhancer, sodium N-(8-[2-hydroxybenzoyl] amino) caprylate, usually shortened to SNAC. That carrier lowers local pH and helps the peptide cross gastric tissue. Both routes deliver the same active molecule.
Semaglutide is a synthetic peptide analog of human glucagon-like peptide-1, a gut hormone released after meals. Its backbone retains the GLP-1 sequence but incorporates two substitutions that slow enzymatic breakdown by dipeptidyl peptidase-4. A short polyethylene glycol linker and a C18 fatty diacid are attached to the peptide chain, allowing the molecule to bind serum albumin and remain in circulation far longer than the native hormone. The result is a circulating half-life measured in days rather than the minutes typical of endogenous GLP-1.
| 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 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。
该分子作为 GLP-1 受体的选择性激动剂发挥作用，受体属于 B 类 G 蛋白偶联受体家族，激活后经 Gs 通路提升细胞内环腺苷酸水平。在胰腺 β 细胞，信号促进葡萄糖依赖性的胰岛素释放，血糖偏低时该作用明显减弱。在胰岛 α 细胞，胰高血糖素分泌受到抑制。中枢神经系统与胃肠道同样存在受体表达，相应信号参与食欲调节以及胃排空速率的降低。
Lyophilised semaglutide is generally held at -20 °C or below, protected from light and moisture. Reconstituted solutions are typically kept at 2-8 °C and used within a defined window because degradation accumulates over time. Repeated freeze-thaw cycles are discouraged, since each cycle can promote aggregation and reduce monomeric content. Room-temperature stability of the solid has been examined in some studies but remains incompletely characterised for long durations, so cold storage is the conservative default for research material.
Degradation proceeds along several parallel routes. Deamidation of asparagine and glutamine residues generates charged variants that shift retention time in chromatographic analysis. Oxidation targets methionine and can be accelerated by trace metals or dissolved oxygen. Non-covalent aggregation produces dimers, oligomers, and larger species that are difficult to reverse. Isomerisation at aspartate residues is slower but measurable under thermal stress. The distribution among these pathways depends on pH, buffer composition, ionic strength, and the presence of excipients such as sugars or surfactants.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nm is the standard purity method, reported as area percent. Mass spectrometry, usually with electrospray ionisation, confirms identity and reveals covalent modifications. Size-exclusion chromatography quantifies aggregates and fragments. Peptide mapping after enzymatic digestion localises changes to specific sequence regions. Circular dichroism and infrared spectroscopy report on secondary structure, while light scattering tracks particle formation in liquid formulations. No single technique captures every quality attribute.
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.
Handling practices center on minimizing contamination and adsorption. Lyophilized peptide tends to accumulate static charge, so weighing is done with antistatic measures and calibrated balances. Reconstitution with appropriate solvent should be gentle, avoiding vigorous vortexing that generates foam and shear. Solutions are typically aliquoted before freezing to reduce repeated temperature cycling. Personal protective equipment and a fume hood are standard for powder handling.
Reconstituted solutions are less stable than the dry powder, and stability depends on concentration, pH, buffer composition, and container material. Low-protein-binding tubes reduce loss of peptide to plastic surfaces. Some researchers add a carrier protein to limit adsorption at low concentrations. The exact shelf life of a given solution is best determined empirically through a stability study rather than assumed from general guidance, because published data cover only a limited set of conditions.
Botha wanted all the Cuban military personnel to be withdrawn, and over a period of twelve months rather than three years. He also countered that the Namibian independence process could only take place once the Cuban withdrawal was initiated. The Lusaka Accords were abandoned in the wake of Operation Argon, a failed sabotage mission carried out by South African special forces in Angola's oil-rich Cabinda exclave. Four years of military escalation and massive defence expenditures had a drastic impact on Angola's state finances, which were only being balanced by petroleum revenue. The largest oil refinery in the country was located on the Cabindan coast and operated by a US firm, Gulf Oil, under the auspices of the Cabina-Gulf Oil National Petroleum Company of Angola (SONAGOL). By 1984 Gulf had invested over 1.3 billion dollars in its Cabinda operation, which was exporting 165,495 barrels of oil per day. At the time, the revenue from the Gulf refinery generated 90% of Angola's foreign exchange. The Reagan administration separated its political positions on Angola from its position on SONAGOL, with Crocker hoping that American multinational companies in general, and Gulf in particular, would be a moderating force on the Marxist government. South Africa had noted the critical importance of the refinery's contribution to the FAPLA war effort and had begun investigating ways to disrupt it without incurring the ire of the US, which would have to react if American commercial interests were threatened.
== Taxonomy == The type specimen for Nolina lindheimeriana was collected by Lindheimer on a rocky plateau northeast of "Neubraunfels," now New Braunfels, Texas, in June or July of 1846. The genus name Nolina was chosen in honor of Abbé C. P. Nolin, a French arborist and director of the royal nurseries during the 1700s. The species name lindheimeriana was chosen to honor Ferdinand Lindheimer, the "Father of Texas Botany."
==== Cover-up allegations ==== Fonterra notified the New Zealand government on 5 September and three days later, Prime Minister Helen Clark had Beijing officials alerted directly. News reports began circulating in China on 9 September, and the news was broken internationally by Reuters the following day. The state-controlled media report did not initially identify the company involved. Posts on Chinese social portal Tianya named Sanlu as the culprit, which Sanlu denied. According to a State Council investigation, Sanlu had known about infants made sick by its products as early as December 2007, but no testing was performed until June 2008. It said leading government officials in Shijiazhuang city had failed to report the contamination to provincial and state authorities (until 9 September) in violation of rules on reporting major incidents involving food safety. According to the People's Daily, on 2 August, Sanlu asked the Shijiazhuang city government to assist them in controlling the media's reporting of the recall. According to accounts confirmed by media reports and health officials, the company tried to buy off critics and cover up the contamination. In a memo dated 11 August, Beijing-based public relations agency Teller International advised Sanlu to seek cooperation with major search engines to censor negative information. The agency reportedly had repeatedly contacted key account staff at Baidu and proposed a ¥3 million (US$440,000) budget to screen all negative news.
CIDP is a neurological disorder caused by an injury to the protective coating of the nerves as they leave the brain. However, this was almost immediately ruled out by his physicians as testing was already done against the possibility of CIDP. Leaving the paralysis to be a rare side effect of the clinical drug, Ibrutinib Joe was taking to control his blood cancer, only he hasn't been taking the medication since a blood clot almost killed him. Dr. Lisa Sanders suggests that his regaining feeling in his toes is a result of Joe being off the medication, as it could take up to a year for the medication to fully leave his body and for the nerves to rebuild themselves. This raises the issue that if Joe stays off the medication he might be able to walk again but if he doesn't get back on he will have nothing controlling his blood cancer. Dr. Lisa Sanders later published Ann’s story on the column and awaited the response from the audience. The audience presented with many possibilities but Ann’s doctors had tested and ruled them all out except for two. The first possibility is Lyme Disease which is an infection caused by bacteria transmitted through ticks. While Ann’s symptoms are not in line with that of Lyme Disease, the disease is known for causing all kinds of strange and interesting neurological problems. The second possibility is that Ann has a Functional Neurological Disorder, where simply her body is not transmitting the correct signals.
Mohammad Azam Nuristani, a political activist from Nuristan, said that the Taliban lacked the ability to reopen roads closed by Pakistani forces and were preventing residents from speaking publicly about the issue. He also said, citing images and other sources, that Pakistan had seized a strategic point in Nuristan and was seeking to prolong the conflict on Afghan soil through Khost and Nuristan. On the same day, Pakistani officials stated that, since the start of Operation Ghazab-lil-Haq, terror-related incidents in Khyber Pakhtunkhwa had fallen by 65%. According to officials, Khyber Pakhtunkhwa recorded 240 terror-related incidents before the operation, which declined to 80 following the start of the military operation, Punjab Counterterrorism Department also claimed to have captured 36 "suspected terrorists" including two Pakistani Taliban. A policeman and two militants were killed, three policemen and four militants were injured in two engagements in Bannu District. TTP killed two Federal Constabulary in Kohat District. On 29 March, Taliban forces and Pakistani border guards engaged in an artillery duel which affected parts of Afghanistan's Kunar province and Pakistan's Bajaur district. Taliban officials said that an artillery shelling by Pakistani forces on areas in Asadabad, the provincial capital of Kunar province, had killed one civilian and injured sixteen others. On the same day, Afghan Foreign Minister, Amir Khan Muttaqi, said Afghanistan wanted to resolve tensions with Pakistan through dialogue and mutual understanding.
Sources: en.wikipedia.org
In fish, the esophagus is often lined with columnar epithelium, and in amphibians, sharks and rays, the esophageal epithelium is ciliated, helping to wash food along, in addition to the action of muscular peristalsis. In addition, in the bat Plecotus auritus, fish and some amphibians, glands secreting pepsinogen or hydrochloric acid have been found. The muscle of the esophagus in many mammals is initially striated but then becomes smooth muscle in the caudal third or so. In canines and ruminants, however, it is entirely striated to allow regurgitation to feed young (canines) or regurgitation to chew cud (ruminants). It is entirely smooth muscle in amphibians, reptiles and birds. Contrary to popular belief, an adult human body would not be able to pass through the esophagus of a whale, which generally measures less than 10 cm (4 in) in diameter, although in larger baleen whales it may be up to 25 cm (10 in) when fully distended.
A review of four studies on the effectiveness of mindfulness-based cognitive therapy (MBCT), a recently developed class-based program designed to prevent relapse, suggests that MBCT may have an additive effect when provided with the usual care in patients who have had three or more depressive episodes, although the usual care did not include antidepressant treatment or any psychotherapy, and the improvement observed may have reflected non-specific or placebo effects. Of note, although Mindfulness-based cognitive therapy for depression prevented relapse of future depressive episodes, there is no research on whether it can cause the remission of a current depressive episode. Interpersonal psychotherapy (IPT) focuses on the social and interpersonal triggers that may cause depression. There is evidence that it is an effective treatment for depression. Here, the therapy takes a fairly structured course (often 12 sessions, as in the original research versions) as in the case with CBT; however, the focus is on relationships with others. Unlike family therapy, IPT is an individual format, so it is possible to work on interpersonal themes even if other family members do not come to the session. Therapy can be used to help a person develop or improve interpersonal skills in order to allow him or her to communicate more effectively and reduce stress. In a meta-analysis of 16 studies and 4,356 patients, the average improvement in depressive symptoms was an effect size of d = 0.63 (95% CI, 0.36 to 0.90).
=== CO2 absorption === Hydrated products of Portland cement, such as concrete and mortars, slowly reabsorb atmospheric CO2 gas, which has been released during calcination in a kiln. This natural process, reversed to calcination, is called carbonation. As it depends on CO2 diffusion into the bulk of concrete, its rate depends on many parameters, such as environmental conditions and surface area exposed to the atmosphere. Carbonation is particularly significant at the latter stages of the concrete life - after demolition and crushing of the debris. It is estimated that nearly 30% of atmospheric CO2 generated by cement production is reabsorbed during the life-cycle of cement products. Carbonation process is considered as a mechanism of concrete degradation. It reduces pH of concrete that promotes reinforcement steel corrosion. However, as the product of Ca(OH)2 carbonation, CaCO3, occupies a greater volume, porosity of concrete reduces. This increases strength and hardness of concrete. There are proposals to reduce carbon footprint of hydraulic cement by adopting non-hydraulic cement, lime mortar, for certain applications. It reabsorbs some of the CO2 during hardening, and has a lower energy requirement in production than Portland cement. A few other attempts to increase absorption of carbon dioxide include cements based on magnesium (Sorel cement).
==== Inhaled substances (pneumoconiosis) ==== Inorganic Silicosis Asbestosis Berylliosis Industrial printing chemicals (e.g. carbon black, ink mist) Organic Hypersensitivity pneumonitis (extrinsic allergic alveolitis), representing approximately 15% of cases of ILD.
==== Physical violence ==== The stigma surrounding borderline personality disorder includes the belief that people with BPD are prone to violence toward others. While movies and visual media often sensationalize people with BPD by portraying them as violent, the majority of researchers agree that people with BPD are unlikely to harm others physically. Although people with BPD often struggle with experiences of intense anger, a defining characteristic of BPD is that they direct it inward toward themselves. One 2020 study found that BPD is individually associated with psychological, physical, and sexual forms of intimate partner violence (IPV), especially amongst men. In terms of the AMPD trait facets, hostility (negative affectivity), suspiciousness (negative affectivity) and risk-taking (disinhibition) were most strongly associated with IPV perpetration for the total sample. In addition, adults with BPD have often experienced abuse in childhood, so many people with BPD adopt a "no-tolerance" policy toward expressions of anger of any kind. Their extreme aversion to violence can cause many people with BPD to overcompensate and experience difficulties being assertive and expressing their needs. This is one reason why people with BPD often choose to harm themselves over potentially causing harm to others.
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.
Native GLP-1 is degraded within minutes by circulating enzymes. The synthetic version carries substitutions at positions that block enzymatic cleavage, plus a fatty acid side chain that promotes albumin binding. These two changes together extend circulation time from minutes to roughly a week.