The short version of Lyophilisation fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-10-06. Anything still debated is marked as such rather than presented as settled.
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.
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 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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular class | 31-amino-acid peptide | Modified glucagon-like peptide-1 analogue |
| Molecular mass | approximately 4114 Da | Calculated for the free peptide backbone |
| Appearance | white to off-white powder | Typical of purified lyophilised peptide batches |
| Solubility class | freely soluble in water | Aqueous solubility improves at slightly alkaline pH |
| Typical storage | -20 degrees Celsius, dry, dark | Protect from repeated freeze-thaw cycles |
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.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1, a hormone released from intestinal L cells after food intake. The molecule is a 31-amino-acid backbone modified at three positions to resist cleavage by dipeptidyl peptidase-4, the enzyme that degrades native GLP-1 within minutes. A lysine residue at position 26 carries a linker and a C18 fatty diacid, which promotes binding to serum albumin and slows renal clearance. These changes extend the circulating half-life from roughly two minutes to about one week in humans.
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.
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.
Le Havre appears in several literary works as a point of departure to America: in the 18th century, Father Prevost embarked Manon Lescaut and Des Grieux for French Louisiana. Fanny Loviot departed from Le Havre in 1852, as an emigrant to San Francisco and points further west, and recounted her adventures in Les pirates chinois (A Lady's Captivity among Chinese Pirates in the Chinese Seas, 1858). In the 19th century, Le Havre was the setting for several French novels: Honoré de Balzac described the failure of a Le Havre merchant family in Modeste Mignon. Later, the Norman writer Guy de Maupassant located several of his works at Le Havre such as Au muséum d'histoire naturelle (At the Museum of Natural History) a text published in Le Gaulois on 23 March 1881 and again in Pierre et Jean. Alphonse Allais located his intrigues at Le Havre too. La Bête humaine (The Human Beast) by Émile Zola evokes the world of the railway and runs along the Paris–Le Havre railway. Streets, buildings, and public places in Le Havre pay tribute to other famous Le Havre people from this period: the writer Casimir Delavigne (1793–1843) has a street named after him and a statue in front of the palace of justice alongside another man of letters, Bernardin de Saint-Pierre (1737–1814). In the 20th century, Henry Miller located part of the action in Le Havre in his masterpiece Tropic of Cancer, published in 1934. Bouville was the commune where the writer lived who wrote his diary in La Nausée (The Nausea) (1938) by Jean-Paul Sartre who was inspired by Le Havre city where he wrote his first novel.
Alveolar macrophages are phagocytes that play a critical role in homeostasis, host defense, and tissue remodeling. Their population density is decisive for these many processes. They are highly adaptive and can release many secretions, to interact with other cells and molecules using several surface receptors. Alveolar macrophages are also involved in the phagocytosis of apoptotic and necrotic cells. They need to be selective of the material that is phagocytized to safeguard the normal cells and structures. To combat infection, the phagocytes facilitate many pattern recognition receptors (PRRs) to help recognize pathogen-associated molecular patterns (PAMPs) on the surface of pathogenic microorganisms. PAMPs all have the common features of being unique to a group of pathogens but invariant in their basic structure; and are essential for pathogenicity (ability of an organism to produce an infectious disease in another organism). Proteins involved in microbial pattern recognition include mannose receptor, complement receptors, DC-SIGN, Toll-like receptors(TLRs), the scavenger receptor, CD14, and Mac-1. PRRs can be divided into three classes:
=== Mechanism of action (eye drops) === It is a nucleoside analogue, a modified form of deoxyuridine, similar enough to be incorporated into viral DNA replication, but the –CF3 group added to the uracil component blocks base pairing, thus interfering with viral DNA replication.
Sources: en.wikipedia.org
In addition to the birth and death of de novo genes at the level of the ORF, mutational and other processes also subject genomes to constant "transcriptional turnover". One study in murines found that while all regions of the ancestral genome were transcribed at some point in at least one descendant, the portion of the genome under active transcription in a given strain or subspecies is subject to rapid change. The transcriptional turnover of noncoding RNA genes is particularly fast compared to coding genes. De novo open reading frames are expected to undergo substantial early turnover, because neutral-evolution modelling predicts frequent stop-gain losses and only rare, substantial ORF-length increases.
The study Radiological Evaluation of Breasts Reconstructed with Lipo-modeling (2005) indicates that the therapeutic efficacy of fat-graft breast reconstruction in the treatment of radiation therapy damage to the chest, the incidental reduction of capsular contracture, and the improved coverage of the breast implants. In fat-graft breast augmentation procedures, there is the risk that the adipocyte tissue can become necrotic, undergo metastatic calcification, develop cysts, and agglomerate into palpable lumps. Although the cause of metastatic calcification is unknown, the post-procedure biological changes occurred to the fat-graft tissue resemble the tissue changes usual to breast surgery procedures, such as reduction mammoplasty. The pre-procedure mammograms were negative for the presence of the malignant neoplasms of breast cancer. In the 17-patient cohort, two women developed breast cancer after the breast augmentation: one woman at 12 months and the second woman at 92 months. Further, the study Cell-assisted Lipotransfer for Cosmetic Breast Augmentation: Supportive Use of Adipose-Derived Stem/Stromal Cells (2007), in a 40-woman cohort, the inclusion of adipose stem cells in the grafts of adipocyte fat increased the rate of the corrective success of the autologous fat-grafting procedure.
== Causes == NMS is usually caused by antipsychotic drug use, but other dopaminergic blocking drugs can also be a cause. Individuals using butyrophenones (such as haloperidol and droperidol) or phenothiazines (such as promethazine and chlorpromazine) are reported to be at greatest risk. However, various atypical antipsychotics such as clozapine, olanzapine, risperidone, quetiapine, and ziprasidone have also been implicated in cases. NMS may also occur in people taking dopaminergic drugs (such as levodopa) for Parkinson's disease, most often when the drug dosage is abruptly reduced. In addition, other drugs with anti-dopaminergic activity, such as the antiemetic metoclopramide, can induce NMS. Tetracyclics with anti-dopaminergic activity have been linked to NMS in case reports, such as the amoxapines. Additionally, desipramine, dothiepin, phenelzine, tetrabenazine, and reserpine have been known to trigger NMS. Whether lithium can cause NMS is unclear. However, concomitant use of lithium is associated with a higher risk of NMS when a person starts on an antipsychotic drug. At the molecular level, NMS is caused by a sudden, marked reduction in dopamine activity, either from withdrawal of dopaminergic agents or blockade of dopamine receptors.
=== 18th century === The technical knowledge for making hydraulic cement was formalized by French and British engineers in the 18th century. John Smeaton made an important contribution to the development of cements while planning the construction of the third Eddystone Lighthouse (1755–59) in the English Channel now known as Smeaton's Tower. He needed a hydraulic mortar that would set and develop some strength in the twelve-hour period between successive high tides. He performed experiments with combinations of different limestones and additives including trass and pozzolanas and did exhaustive market research on the available hydraulic limes, visiting their production sites, and noted that the "hydraulicity" of the lime was directly related to the clay content of the limestone used to make it. Smeaton was a civil engineer by profession, and took the idea no further. In the South Atlantic seaboard of the United States, tabby relying on the oyster-shell middens of earlier Native American populations was used in house construction from the 1730s to the 1860s. In Britain particularly, good quality building stone became ever more expensive during a period of rapid growth, and it became a common practice to construct prestige buildings from the new industrial bricks, and to finish them with a stucco to imitate stone. Hydraulic limes were favored for this, but the need for a fast set time encouraged the development of new cements. Most famous was Parker's "Roman cement". This was developed by James Parker in the 1780s, and finally patented in 1796.
Sources: en.wikipedia.org
2024 Conservative Party leadership election: Nominations open for the first round of the leadership election. July 2024 Welsh Labour leadership election: Eluned Morgan is elected unopposed as the new leader of Welsh Labour after nominations close at midday. The Senedd will be recalled on 6 August to choose a new First Minister of Wales following the resignation of Vaughan Gething and the subsequent Welsh Labour leadership election. 25 July – Conservative Party leadership election: Tom Tugendhat and Robert Jenrick enter the race to become the next Conservative leader. 26 July – Labour peer Lord Falconer introduces the Assisted Dying Bill into the House of Lords. The bill would allow anyone with a terminal illness and less than six months left to live to get medical assistance to end their life. Following a critical report on the Care Quality Commission, Health Secretary Wes Streeting describes the body as not fit for purpose. Conservative Party leadership election: Former Work and Pensions Secretary Mel Stride becomes the fourth candidate to announce his intention to run for the Conservative Party leadership election. 27 July – Conservative Party leadership election: Priti Patel becomes the fifth candidate to put their name forward for the election, standing as a unity candidate. 28 July – Labour accuses the previous Conservative government of "covering up" "catastrophic" problems in the public sector and creating a multi-billion pound gap in public finances.
All nuclear data not otherwise stated is from the standard source: There are 42 known isotopes of polonium (84Po), all radioactive, stretching from 186Po to 227Po. The isotopes 210 through 218 occur naturally in the four principal decay chains. In terms of curies they are mostly of even mass number, coming from uranium-238 and thorium-232, with smaller amounts of 211 and 215 from uranium-235, and very little with mass number 213 coming from neptunium-237, and much less with mass number 217 coming from a rare branch of the neptunium decay chain. 210Po has the longest half-life by far (138.376 days) and is, therefore, the most abundant by far in terms of moles or mass. It is also the most easily synthesized isotope, by neutron capture on natural bismuth, and so by far the most abundant artificial isotope as well. Two other isotopes have longer lives: 209Po with a half-life of 124 years and 208Po with a half-life of 2.898 years. Both are made by using a cyclotron to bombard bismuth with protons.
=== Pharmacokinetics === Phenelzine is administered orally in the form of phenelzine sulfate and is rapidly absorbed from the gastrointestinal tract. The time to peak plasma concentration is 43 minutes, and the half-life is 11.6 hours. Since phenelzine irreversibly disables MAO, it does not necessarily need to be present in the blood at all times for its effects to be sustained. Because of this, upon phenelzine treatment being ceased, its effects typically do not wear off until the body replenishes its enzyme stores, a process which can take as long as 2–3 weeks. Phenelzine is metabolized primarily in the liver, and its metabolites are excreted in the urine. Oxidation is the primary route of metabolism, and the major metabolites are phenylacetic acid and parahydroxyphenylacetic acid, recovered as about 73% of the excreted dose of phenelzine in the urine over 96 hours after single doses. Acetylation to N2-acetylphenelzine is a minor pathway. Phenelzine may also interact with cytochrome P450 enzymes, inactivating these enzymes through the formation of a heme adduct. Two other minor metabolites of phenelzine, as mentioned above, include phenylethylidenehydrazine and phenethylamine.
=== Cerebral blood flow and oxygen delivery === Although the passage of food into the gastrointestinal tract results in increased blood flow to the stomach and intestines, this is achieved by diversion of blood primarily from skeletal muscle tissue and by increasing the volume of blood pumped forward by the heart each minute. The flow of oxygen and blood to the brain is extremely tightly regulated by the circulatory system and does not drop after a meal.
=== Music === The original motion picture soundtrack for Cry Freedom was released by MCA Records on 25 October 1990. It features songs composed by veteran musicians George Fenton, Jonas Gwangwa and Thuli Dumakude. At Biko's funeral they sing the hymn "Nkosi Sikelel' iAfrika". Jonathan Bates edited the film's music. A live version of Peter Gabriel's 1980 song "Biko" was released to promote the film; although the song was not on the film soundtrack, footage was used in its video. The title song was nominated for the Grammy Award for Best Song Written for Visual Media at the 31st Annual Grammy Awards, but lost to "Two Hearts" from Buster, performed by Phil Collins.
Sources: en.wikipedia.org
It is a glucagon-like peptide-1 receptor agonist, often grouped with the incretin mimetics. Its backbone is modified from the human hormone to resist enzymatic degradation and to bind albumin. These two features distinguish it from the native peptide.
No. It shares high sequence identity but carries non-natural modifications that alter its stability and clearance. The naturally occurring hormone is broken down within minutes, while the synthetic analogue circulates far longer.
Attachment to serum albumin reduces renal filtration of the peptide and shields it from enzymatic breakdown. The consequence is a much longer interval between administrations than unmodified peptides allow. The precise contribution of binding affinity to overall duration is still being quantified.
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.