deamidation is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-11-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Quality control for research material typically involves reversed-phase HPLC for purity and identity, mass spectrometry for molecular weight confirmation, and Karl Fischer titration for residual water content. Peptide content is often reported as the mass of actual peptide rather than total powder mass, since counterions and water contribute to the latter. A certificate of analysis should list the method used for each specification. Limits and acceptance criteria vary by supplier and by intended application.
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.
| 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 |
Stability studies examine how temperature, pH, and moisture influence degradation rates over time. In aqueous solution, hydrolysis and deamidation accelerate as pH moves away from mildly acidic conditions. Light exposure and residual metal ions can also trigger oxidation of susceptible residues. Accelerated aging at elevated temperature is used to estimate shelf life, though extrapolation to room temperature carries uncertainty because individual degradation pathways do not always scale predictably.
Lyophilized semaglutide powder is typically held at minus twenty degrees Celsius for long-term storage. At that temperature, solid-state degradation reactions proceed slowly and the peptide remains intact for extended periods. Repeated freeze-thaw cycles are best avoided because they promote aggregation and can shift the proportion of monomeric peptide present. Working aliquots are often prepared so that each portion is thawed only once, and desiccant is placed inside the vial to limit moisture uptake.
Identity and purity are usually assessed by reverse-phase high-performance liquid chromatography coupled to mass spectrometry. Retention time and observed mass are compared against a reference standard run under identical conditions. Impurity profiles reveal deamidation products, oxidized methionine variants, and truncated fragments that arise during synthesis or storage. Peptide mapping through enzymatic digestion confirms the primary sequence, while amino acid analysis offers an independent check on overall composition.
GLP-1 receptors are expressed on pancreatic beta cells, in the gut, and in several brain regions. Receptor activation raises cyclic AMP, enhances glucose-dependent insulin secretion, and suppresses glucagon release when blood glucose is high. Effects on gastric emptying and on hypothalamic appetite circuits reduce energy intake. Because insulin release remains glucose-dependent, the risk of hypoglycemia is low when the drug is used alone. The precise contribution of each pathway to body weight change in humans remains an area of active investigation.
Clinical studies of semaglutide generally measure glycated hemoglobin, fasting plasma glucose, body weight, and composite cardiovascular endpoints. The SUSTAIN program enrolled adults with type 2 diabetes, while the STEP program focused on obesity without diabetes. Administration follows a stepwise escalation schedule designed to limit gastrointestinal effects during the first weeks. Reported outcomes include mean percentage weight change, the proportion of participants reaching defined weight-loss thresholds, and rates of nausea, vomiting, and diarrhea. Long-term data on durability after treatment stops are still limited and remain a topic of ongoing research.
Semaglutide is a synthetic peptide analog of human glucagon-like peptide-1, developed by Novo Nordisk and first approved in 2017 for type 2 diabetes. It belongs to the incretin mimetic class, a group of agents that reproduce the glucose-dependent actions of endogenous GLP-1. The molecule was engineered to resist degradation by dipeptidyl peptidase-4 and to bind serum albumin, extending its half-life from minutes to roughly one week. Approval for chronic weight management followed in 2021, based on large cardiovascular and obesity outcome trials.
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.
Quality control relies on pharmacopoeial monographs where they exist, combined with in-house specifications for identity, purity, water content, and counter-ion composition. Reference standards allow calibration across laboratories, although certified materials for every analogue are not universally obtainable. Batch records, chromatograms, and mass spectra form the documentation trail. Regulatory classification varies by jurisdiction and intended use, and research-grade material differs from pharmaceutical-grade material in testing scope. Analytical uncertainty is often expressed as relative standard deviation across replicate injections.
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.
Chemical Abstracts Service Current Contents/Physical, Chemical & Earth Sciences EBSCO databases Embase Food Science and Technology Abstracts FRANCIS Inspec PASCAL Science Citation Index Expanded Scopus According to the Journal Citation Reports, the journal has a 2020 impact factor of 1.986.
As a result of the oil crisis, combined with the growing influence of Third World alignments, such as OPEC and the Non-Aligned Movement, less powerful countries had more room to assert their independence and often showed themselves resistant to pressure from either superpower. Meanwhile, Moscow was forced to turn its attention inward to deal with the Soviet Union's deep-seated domestic economic problems. During this period, Soviet leaders such as Leonid Brezhnev and Alexei Kosygin embraced the notion of détente.
One early theoretician of cryopreservation was James Lovelock. In 1953, he suggested that damage to red blood cells during freezing was due to osmotic stress, and that increasing the salt concentration in a dehydrating cell might damage it. In the mid-1950s, he experimented with the cryopreservation of rodents, determining that hamsters could be frozen with 60% of the water in the brain crystallized into ice with no adverse effects; other organs were shown to be susceptible to damage. Cryopreservation was applied to human materials beginning in 1954 with three pregnancies resulting from the insemination of previously frozen sperm. Fowl sperm was cryopreserved in 1957 by a team of scientists in the UK directed by Christopher Polge. During 1963, Peter Mazur, at Oak Ridge National Laboratory in the U.S., demonstrated that lethal intracellular freezing could be avoided if cooling was slow enough to permit sufficient water to leave the cell during progressive freezing of the extracellular fluid. That rate differs between cells of differing size and water permeability: a typical cooling rate around 1 °C/minute is appropriate for many mammalian cells after treatment with cryoprotectants such as glycerol or dimethyl sulfoxide, but the rate is not a universal optimum. On April 22, 1966, the first human cadaver was frozen—it had been embalmed for two months—by being placed in liquid nitrogen and stored at just above freezing. The cadaver was that of an elderly woman from Los Angeles, whose name is unknown, and was soon thawed out and buried by relatives.
Traditional ayahuasca brews are usually made with Banisteriopsis caapi as an MAOI, while dimethyltryptamine sources and other admixtures vary from region to region. There are several varieties of caapi, often known as different "colors", with varying effects, potencies, and uses. DMT admixtures:
After death, a body will decay. Burial is not necessarily a public health requirement. Contrary to conventional wisdom, the World Health Organization advises that only corpses carrying an infectious disease strictly require burial. Human burial practices are the manifestation of the human desire to demonstrate "respect for the dead". Cultures vary in their mode of respect. Some reasons follow:
Sources: en.wikipedia.org
doi:10.1086/590941. PMID 18665816. Wikidata Q45138244. Rajan P Adhikari; Cook, Gregory Murray; Lamont, Iain; Selwyn Lang; Heffernan, Helen Mary; John M B Smith (2002). "Phenotypic and molecular characterization of community occurring, Western Samoan phage pattern methicillin-resistant Staphylococcus aureus". Journal of Antimicrobial Chemotherapy. 50 (6): 825–831. doi:10.1093/jac/dkf242. PMID 12461000. Wikidata Q40686052.
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The production was noted (by Nehad Selaiha of the weekly Al-Ahram) not only for its unexpected change of plot at the very end but also for its chorus of one hundred who alternated their speech between Arabic and English. The translation used was that of George Theodoridis. US Latina playwright Caridad Svich's 2009 play Wreckage, which premiered at Crowded Fire Theatre in San Francisco, tells the story of Medea from the sons' point of view, in the afterlife. Paperstrangers Performance Group toured a critically acclaimed production of Medea directed by Michael Burke to U.S. Fringe Festivals in 2009 and 2010. Bart Lee's interpretation of Medea, renamed Medea, My Dear, was performed in Surrey and later toured the south of England from 2010 to 2011. Luis Alfaro's re-imagining of Medea, Mojada, world premiered at Victory Gardens Theater in 2013. Theatre Lab's production, by Greek director Anastasia Revi, opened at The Riverside Studios, London, on 5 March 2014. The Hungry Woman: A Mexican Medea by Cherríe Moraga takes elements of Medea and of other works. 14 July – 4 September 2014 London Royal National Theatre staging of Euripides in a new version by Ben Power, starring Helen McCrory as Medea, directed by Carrie Cracknell, music by Will Gregory and Alison Goldfrapp. 25 September – 14 November 2015 London Almeida Theatre a new adaptation by Rachel Cusk, starring Kate Fleetwood as Medea, directed by Rupert Goold. 17 February – 6 March 2016 in Austin at the Long Center for the Performing Arts starring Franchelle Stewart Dorn as Medea and directed by Ann Ciccolella.
== List legend == Each group of radionuclides, starting with the longest-lived primordial radionuclides, is sorted by decreasing half-life, but the tables are sortable by other columns. All columns sort by usual lexicographical order; in the case of the nuclide column this gives order on the mass number A.
==== Doping ==== The isotope ratio of carbon in athletes' steroids has been used to determine whether these steroids came from the athlete's body or an outside source. This test has been used in a number of high-profile anti-doping cases and has various benefits over simply characterizing the concentration of various compounds. Attempts are being made to create similar tests based on stable hydrogen isotopes which could be used to complement the existing testing methods. One concern with this method was that the natural steroids produced by the human body may vary significantly based on the 2H content of drinking water, leading to false detection of doping based on HIC differences. This concern has been addressed in a recent study which concluded that the effect of DHR of drinking water did not pose an insurmountable source of error for this anti-doping testing strategy.
Sources: en.wikipedia.org
Yet, the main problem that the socialist government of Felipe González had to face was the appearance of new scandals, which resulted in a harsh confrontation with the opposition, both the People's Party and the United Left, so that the fourth socialist mandate would be known as the "legislature of tension." The one with the greatest popular and media impact was the "Roldán case", named after the then director of the Civil Guard, Luis Roldán, who was arrested accused of having amassed a fortune thanks to his position and who four months later, in April 1994, went on the run. The former Interior Minister who appointed Roldán, José Luis Corcuera, had to resign as a deputy, as did the Interior Minister at the time, Antoni Asunción, for letting him escape. Roldán was arrested a year later in Laos and sent back to Spain where he was tried and sentenced to 28 years in prison.
Pseudomonas aeruginosa produces the pigments pyocyanin and pyoverdin, which give the colonies a greenish sheen. Some specimens of Serratia marcescens produce an orange-red pigment called prodigiosin. Organisms with swarming motility, like Proteus species, exhibit concentric waves of growth extending from the inoculation point.
Side effects of fentanyl analogues are similar to those of fentanyl itself, which include itching, nausea and potentially serious respiratory depression, which can be life-threatening. Illicitly used fentanyl analogues have killed hundreds of people throughout Europe and the former Soviet republics since the most recent resurgence in use began in Estonia in the early 2000s, and novel derivatives continue to appear.
Thirdly, succinylcholine use has been associated with postoperative myalgia, where patients often experience muscle pain similar to that of post-exercise muscle pain mainly in the shoulders, neck, neck and upper abdominal muscle the following day after surgery, especially in young healthy patients with greater muscle mass, whereas reports from children, elderly and pregnant woman are less frequent. This is caused by the fasciculations (muscle twitches) that appear in sites such as intercostal muscles, and the diaphragm. These fasciculations are not relieved through analgesics, and in common practice, a sub-paralyzing dose of non-depolarizing neuromuscular blocker is administered a few minutes before succinylcholine administration to reduce visible fasciculation and postoperative myalgia. The use of succinylcholine is therefore also contraindicated in patient with muscle myopathy within 24 to 72 hours post-administration. Non-depolarizing drug Atracurium: Atracurium is commonly associated with histamine-related symptoms, most notably flushing and erythema. Less commonly seen adverse effects include urticaria, hypotension, wheezing, tachycardia, bronchospasm, dyspnea, bradycardia, and laryngospasm. Moreover, drops of up to 30 mmHg in mean arterial pressure was also observed within two minutes of administration in some patients. H1 and H2 receptor blocking agents can be used to attenuate the drop in mean arterial pressure. A slow injection speed between 30 and 60 seconds reduces adverse effects.
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.
Sealed, protected from light, and refrigerated at two to eight degrees Celsius for most research material. Desiccated storage limits moisture uptake. Allow the vial to reach room temperature before opening to prevent condensation.