This is a working overview of Adsorption, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-09-07. Anything still debated is marked as such rather than presented as settled.
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。
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.
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.
| 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 |
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.
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.
Receptor activation raises intracellular cyclic AMP through Gs coupling, which promotes glucose-dependent insulin release and suppresses glucagon secretion when blood glucose is elevated. Effects outside the pancreas include slower gastric emptying and altered appetite signalling in the hypothalamus and hindbrain. The relative contribution of each tissue to overall metabolic outcomes remains an area of active investigation. Central mechanisms in particular are inferred mainly from animal models and indirect human measures rather than direct observation.
Serum protein binding dominates the pharmacokinetic profile. The attached chain associates strongly with albumin, shielding the peptide from enzymatic attack and slowing filtration by the kidney. This interaction extends the circulation half-life to roughly one week in humans, which supports weekly administration intervals. An oral version pairs the peptide with an absorption enhancer that transiently alters gastric epithelium, permitting limited uptake; bioavailability by that route is substantially lower than by injection.
Semaglutide belongs to the glucagon-like peptide-1 receptor agonist class, a group of synthetic peptides that imitate an incretin hormone released by intestinal L cells after food intake. Native GLP-1 circulates for only a few minutes because dipeptidyl peptidase-4 cleaves it rapidly. The hormone acts on pancreatic islets, the gastrointestinal tract, and several brain regions. Because the natural peptide is short-lived, development work concentrated on analogues that keep receptor activity while resisting enzymatic breakdown and renal clearance.
Current fields that materials physicists work in include electronic, optical, and magnetic materials, novel materials and structures, quantum phenomena in materials, nonequilibrium physics, and soft condensed matter physics. New experimental and computational tools are constantly improving how materials systems are modeled and studied and are also fields when materials physicists work in. The field is inherently interdisciplinary, and the materials scientists or engineers must be aware and make use of the methods of the physicist, chemist and engineer. Conversely, fields such as life sciences and archaeology can inspire the development of new materials and processes, in bioinspired and paleoinspired approaches. Thus, there remain close relationships with these fields. Conversely, many physicists, chemists and engineers find themselves working in materials science due to the significant overlaps between the fields.
==== History ==== In the United Kingdom, house officer posts used to be optional for those going into general practice, but almost essential for progress in hospital medicine. The Medical Act 1956 made satisfactory completion of one year as house officer necessary to progress from provisional to full registration as a medical practitioner. The term "intern" was not used by the medical profession, but the general public were introduced to it by the US television series Dr. Kildare. They were usually called "housemen", but the term "resident" was also used unofficially. In some hospitals the "resident medical officer" (RMO) (or "resident surgical officer" etc.) was the most senior of the live-in medical staff of that specialty. The pre-registration house officer posts lasted six months, and it was necessary to complete one surgical and one medical post. Obstetrics could be substituted for either. In principle, general practice in a "Health Centre" was also allowed, but this was almost unheard of. The posts did not have to be in general medicine: some teaching hospitals had very specialised posts at this level, so it was possible for a new graduate to do neurology plus neurosurgery or orthopaedics plus rheumatology, for one year before having to go onto more broadly based work. The pre-registration posts were nominally supervised by the General Medical Council, which in practice delegated the task to the medical schools, who left it to the consultant medical staff. The educational value of these posts varied enormously.
== External links == David S, Lancaster T, Stead LF. Opioid antagonists for smoking cessation (Cochrane Review), The Cochrane Library, Issue 2, 2005. Chichester, UK: John Wiley & Sons, Ltd. Opioid+Antagonists at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
Sources: en.wikipedia.org
In 1928, under Joseph Peter Grace's leadership, an agreement between Grace and Pan American formed Pan American-Grace Airways (or Panagra), a United States international carrier flying down the west coast of South America. Panagra ultimately evolved into a jet carrier flying from Miami and New York to South America before merging with Braniff Airways in 1967, becoming Braniff's South American network. These routes were sold to Eastern Air Lines in 1982 and then to American Airlines in 1990. In 1929, the vice president at that time, D. Stewart Inglehart, became president, and Joseph Peter Grace was elected chairman of the board of the company.In 1945, the founder's grandson and Joseph Peter Grace's son, J. Peter Grace, became president. Under his leadership, the company owned the country's largest oil-drilling fleet as of 1990-1993, managed its subsidiary Grace Cocoa, which was one of the world's leading suppliers of cocoa bean and chocolate ingredients as of 1992, as well as sugar plantations in Peru, cotton mills in Chile, silver, clay, phosphate, and tin mines. Through its Davison Chemical Division, the company had processed various nuclear materials under a contract from the United States Atomic Energy Commission (AEC). New companies such as Grace Petroleum, Grace Drilling, and Grace Healthcare were created under the umbrella of the Grace Corporation. Grace owned a food group that operated 900 chain restaurant locations, and a retail division with chains for sporting goods, home improvement, jewelry, aftermarket automotive parts and leather goods.
=== September === 17 September – President Lula signs a decree to increase the benefits of the Bolsa Familia program by 15%. 20 September – The Superior Electoral Court rejects a petition to extend voting time amidst Simchat Torah, which falls on 4 October, the day of the nation's first round of elections. 21 September – A helicopter crashes in Santa Catarina, killing all five people on board including singer Rick Sollo. 25 September – President Lula issues a provisional order banning online gambling and sports betting.
== Ecology == The diet of the arapaima consists of fish, crustaceans, fruits, seeds, insects, and small land animals that walk near the shore (such as mammals and birds). The fish is an air breather, using its labyrinth organ, which is rich in blood vessels and opens into the fish's mouth, an advantage in oxygen-deprived water that is often found in the Amazon River. This fish is able to survive in oxbow lakes with dissolved oxygen as low as 0.5 ppm. In the wetlands of the Araguaia, one of the most important refuges for this species, it is the top predator in such lakes during the low-water season, when the lakes are isolated from the rivers and oxygen levels drop, rendering its prey lethargic and vulnerable. Arapaima may leap out of the water if they feel constrained by their environment or harassed.
== Research == It has been used in experiments related to coeliac disease and rheumatoid arthritis. 9 Meters Biopharma was conducting clinical trials for larazotide for Celiac Disease, but announced in 2022 that it would discontinue their Phase 3 clinical trial.
Sources: en.wikipedia.org
The European Central Bank's 'primary objective... shall be to maintain price stability. Without prejudice to that objective, it shall support the general economic policies in the Union', such as 'balanced economic growth and price stability, a highly competitive social market economy, aiming at full employment and social progress, and a high level of protection and improvement of the quality of the environment.' There are three main powers to achieve these goals. First, the ECB can require other banks to hold reserves proportionate to their type of lending. Second, it may lend money to other banks, or conduct 'credit operations'. Third it may 'operate in the financial markets by buying and selling' securities. For example, in Gauweiler v Deutscher Bundestag a German politician claimed that the ECB's purchase of Greek government debt on secondary markets violated TFEU article 123, which prohibits directly lending money to member state governments. The Court of Justice rejected that the ECB had engaged in 'economic policy' (i.e. fiscal transfers) rather than monetary policy decisions, which it was allowed to do. So far the ECB has failed to use these powers to eliminate investment in fossil fuels, despite the inflation that gas, oil and coal cause given their price volality in international markets. Beyond the central bank, the Credit Institutions Directive 2013 requires authorisation and prudence provisions in other banks in all EU member states.
Detection of myositis-specific autoantibodies (MSAs), including anti-Mi-2, anti-NXP2, anti-TIF1-γ, anti-MDA5, and anti-SAE. These autoantibodies are considered pathogenic and are typically mutually exclusive, with most patients harboring only a single MSA. Muscle weakness in both thighs or both upper arms. Using a blood test, finding higher levels of enzymes found in skeletal muscle, including creatine kinase, aldolase, and glutamate oxaloacetate, pyruvate transaminases or lactate dehydrogenase. Using electromyography (testing of electric signalling in muscles), finding all three of: erratic, repetitive, high-frequency signals; short, low-energy signals between skeletal muscles and motor neurons that have multiple phases; and sharp activity when a needle is inserted into the muscle. Examining a muscle biopsy under a microscope demonstrating perifascicular atrophy, increased expression of type I interferon–inducible markers (predominantly in the perifascicular regions), mononuclear white blood cells between the muscle cells, and finding abnormal muscle cell degeneration and regeneration, dying muscle cells, and muscle cells being consumed by other cells (phagocytosis). Rashes typical of dermatomyositis, which include heliotrope rash, Gottron's sign, and Gottron's papules. The fifth criterion is what differentiates dermatomyositis from other forms of inflammatory myopathy. Patients with antisynthetase autoantibodies, such as anti-Jo-1, may also present with dermatomyositis-like skin manifestations.
Fluid pressure is most often the compressive stress at some point within a fluid. (The term fluid refers to both liquids and gases – see below for more information specifically about liquid pressure or gas pressure.) Fluid pressure occurs in one of two situations:
Rosett (1953), dean of the University of Chicago Booth School of Business, Arts and Sciences at Washington University in St. Louis, and chairman of National Bureau of Economic Research Robert L. Friedheim (1955), former director of the USC School of International Relations Calvin B. T. Lee (1955), former chancellor of University of Maryland, Baltimore County and acting president of Boston University Robert E. Paaswell (1956), civil engineer, former interim president of City College of New York and CEO of Chicago Transit Authority Kenneth Gros Louis (1959), chancellor of Indiana University system Richard A. Merrill (1959), 7th dean of the University of Virginia School of Law Stephen Joel Trachtenberg (1959), president of the University of Hartford and of George Washington University David C. Levy (1960), dean of the Parsons School of Design and president of the Corcoran Gallery of Art Steven M. Cahn (1966), provost and acting president of Graduate Center of the City University of New York Dimitri B. Papadimitriou (1970), executive vice president and provost of Bard College David Rubin (1970), professor of communications and dean of S. I. Newhouse School of Public Communications Alan Cooper (1971), provost of Jewish Theological Seminary of America, former member of Sha Na Na William Germano (1972), dean of the faculty of humanities and social sciences at Cooper Union, former editor-in-chief of Columbia University Press Saul Levmore (1973), commercial law scholar, former dean of the University of Chicago Law School Ronald Mason Jr.
Though the allograft (skin transplanted from a member of the same species) is replaced by granulation tissue and is not actually incorporated into the healing wound, it encourages cellular proliferation and provides a structure for epithelial cells to crawl across. On the most difficult chronic wounds, allografts may not work, requiring skin grafts from elsewhere on the patient, which can cause pain and further stress on the patient's system. Collagen dressings are another way to provide the matrix for cellular proliferation and migration, while also keeping the wound moist and absorbing exudate. Additionally Collagen has been shown to be chemotactic to human blood monocytes, which can enter the wound site and transform into beneficial wound-healing cells. Since levels of protease inhibitors are lowered in chronic wounds, some researchers are seeking ways to heal tissues by replacing these inhibitors in them. Secretory leukocyte protease inhibitor (SLPI), which inhibits not only proteases but also inflammation and microorganisms like viruses, bacteria, and fungi, may prove to be an effective treatment. Research into hormones and wound healing has shown estrogen to speed wound healing in elderly humans and in animals that have had their ovaries removed, possibly by preventing excess neutrophils from entering the wound and releasing elastase. Thus the use of estrogen is a future possibility for treating chronic wounds.
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。
Filtering removes particulate matter that can block columns or scatter light. A 0.22 micrometre membrane is typical, and the filter material should be checked for peptide adsorption.