This is a working overview of mass spectrometry, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-09 and is reviewed periodically as new material appears.
Stability depends strongly on physical state. Dry powder is comparatively robust when held at -20 °C or below, desiccated and shielded from light; under those conditions degradation is slow and measured over years. Once dissolved, the peptide becomes far more vulnerable: backbone hydrolysis, oxidation of susceptible residues and aggregation all proceed faster in solution, and the rates climb with temperature and with pH far from neutral. Refrigerated storage at 2–8 °C extends usable life for short periods, and repeated freeze–thaw cycles are best avoided.
Identity and purity are established by instrumental methods rather than by appearance. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and yields a purity value, usually expressed as the share of total peak area. Mass spectrometry checks that the observed mass agrees with the mass calculated from the published sequence, while peptide mapping or amino acid analysis adds structural evidence. Water content, counter-ion identity and residual solvents are sometimes reported as well. A certificate of analysis should name the method behind each figure, because results are method-dependent.
Published information places retatrutide in clinical development rather than on the market as an approved therapy. Early-stage and mid-stage trials have examined tolerability and changes in body weight, and larger studies continue to report results over time. Open questions include the durability of effects after treatment stops, the composition of weight lost, and cardiovascular outcomes over long periods. Statements about definitive benefit should therefore be treated as provisional. Regulatory status varies by jurisdiction and changes as applications are reviewed.
Retatrutide is an investigational synthetic peptide designed to activate three distinct receptor systems within a single molecule. Its pharmacological profile combines activity at the glucose-dependent insulinotropic polypeptide receptor, the glucagon-like peptide-1 receptor, and the glucagon receptor. This arrangement places it within a broader class of agents often described as multi-agonists, which contrast with compounds that engage one or two targets. Research interest centers on whether simultaneous signaling produces effects that single-receptor agonists cannot achieve alone. A single molecular entity also simplifies manufacturing and delivery logistics compared with combining separate agents.
Mechanistic proposals link each receptor to a different physiological role. Activation of the glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptors is associated with reduced appetite, slower gastric emptying, and glucose-dependent insulin release. Glucagon receptor signaling, by contrast, is associated with increased energy expenditure and altered lipid handling, though it can also raise blood glucose. The design intent is to balance these contributions so that weight reduction is enhanced without unacceptable glycemic trade-offs. How well that balance holds across individuals is not fully resolved.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | 95 per cent or higher by RP-HPLC | Tighter grades reported near 98 per cent |
| Identity confirmation | Mass match by LC-MS | Observed mass compared with sequence-derived mass |
| Storage after dissolution | 2–8 °C, protected from light | Short-term use; avoid repeated freeze–thaw |
| Main degradation routes | Hydrolysis, oxidation, aggregation | Backbone and side-chain susceptibility in solution |
| Common diluents | Sterile water or bacteriostatic water | Choice depends on assay and sterility needs |
== Career == After his studies at Leipzig had ended, he began a year of work at the Moabit Hospital in Berlin as the resident pathologist. During this time, he began his research and studies on the issue of atherosclerosis. His first published works, dated during this period were in on the development of atherosclerosis in experimental animals when administered cholesterol. He also spent time working in the laboratory of Peter Rona at the Berlin Municipal Hospital. In 1926, Schoenheimer was invited by Ludwig Aschoff to join the faculty at the University of Freiburg. There he worked as an assistant professor. The investigation of pathological material was part of his work duties. During this time, he also researched atherosclerosis and the role of dietary cholesterol in its development. He became the active in 1927, and then the titular, head of his division in 1931. In 1930, until 1931, Schoenheimer was in the United States as the Douglas Smith Fellow at the University of Chicago. During this time Schoenheimer came into contact with the Josiah Macy Jr Foundation. Later in 1931, The Macy Foundation, with Ludwig Kast as its president, started supporting Schoenheimer in his atherosclerosis studies. Following his fellowship, he returned to the University of Freiburg, taking the position of head of the Pathological Chemistry department.
Caffeine from coffee or other beverages is absorbed by the small intestine within 45 minutes of ingestion and distributed throughout all bodily tissues. Peak blood concentration is reached within 1–2 hours. It is eliminated by first-order kinetics. Caffeine can also be absorbed rectally, evidenced by suppositories of ergotamine tartrate and caffeine (for the relief of migraine) and of chlorobutanol and caffeine (for the treatment of hyperemesis). However, rectal absorption is less efficient than oral: the maximum concentration (Cmax) and total amount absorbed (AUC) are both about 30% (i.e., 1/3.5) of the oral amounts. Caffeine's biological half-life – the time required for the body to eliminate one-half of a dose – varies widely among individuals according to factors such as pregnancy, other drugs, liver enzyme function level (needed for caffeine metabolism) and age. In healthy adults, caffeine's half-life is between 3 and 7 hours. The half-life is decreased by 30–50% in adult male smokers, approximately doubled in women taking oral contraceptives, and prolonged in the last trimester of pregnancy. In newborns the half-life can be 80 hours or more, dropping rapidly with age, possibly to less than the adult value by age 6 months. The antidepressant fluvoxamine (Luvox) reduces the clearance of caffeine by more than 90%, and increases its elimination half-life more than tenfold, from 4.9 hours to 56 hours.
where shg (resp. tpef) is the number of thresholded pixels in the SHG (resp. 2PEF) image, a high MFSI meaning a pure SHG image (with no fluorescence). The highest MFSI is found in cancerous tissues, which provides a contrast mode to differentiate from normal tissues. SHG was also combined to Third-Harmonic Generation (THG) to show that backward (see #Forward over backward SHG) THG is higher in tumors.
=== Organic chemistry === In organic chemistry, menthol is used as a chiral auxiliary in asymmetric synthesis. For example, sulfinate esters made from sulfenyl chlorides and menthol can be used to make enantiomerically pure sulfoxides by reaction with organolithium reagents or Grignard reagents. Menthol reacts with chiral carboxylic acids to give diastereomic menthyl esters, which are useful for chiral resolution.
=== Pregnancy and breastfeeding === Although there are no major human studies of prednisolone use in pregnant women, studies in several animals show that it may cause birth defects including increased likelihood of cleft palate. Prednisolone is found in the breast milk of mothers taking prednisolone.
Sources: en.wikipedia.org
In a speech to the Scottish Labour Party conference in Edinburgh, Labour leader Sir Keir Starmer rules out a deal with the SNP "under any circumstances", and warns against complacency following the departure of Nicola Sturgeon as SNP leader and First Minister. 20 February – Finance Secretary Kate Forbes announces she is running in the Scottish National Party leadership election. 21 February Kate Forbes insists her campaign to become the next SNP leader has not been derailed after she lost the support of several colleagues following comments about same-sex marriage and having children outside marriage, both of which she is opposed to as a member of the Free Church of Scotland. MSPs vote 68–57 to approve the Scottish Government's budget for the 2023–24 financial year, which includes a tax rise for everyone in Scotland earning more than £43,662. 23 February – Sir Iain Livingstone announces he will retire as Chief Constable of Police Scotland in the summer after five years in the post. 24 February Nominations close for the SNP leadership election, with Kate Forbes, Ash Regan and Humza Yousaf having all reached the threshold of supporters to go forward into the contest. Two crew died after tugboat capsized & sank close to Greenock harbour. 25 February – Members of the Scottish Secondary Teachers' Association (SSTA) vote to accept a new pay offer from the Scottish Government, and announce they have suspended strike action scheduled for the following week. 28 February – Transgender rapist Isla Bryson is sentenced to eight years in prison with a further three years supervision.
==== Memoirs ==== Peart, Neil. Far and Wide: Bring that Horizon to Me! ECW Press, 2016. ISBN 978-1770413481. Peart, Neil. Ghost Rider: Travels on the Healing Road. ECW Press, 2002. ISBN 1-55022-546-4 (hardcover), ISBN 1-55022-548-0 (paperback). Peart, Neil. The Masked Rider: Cycling in West Africa. Pottersfield Press, 1996. ISBN 1-895900-02-6. Peart, Neil. Roadshow: Landscape With Drums – A Concert Tour By Motorcycle. Rounder Books, 2006. ISBN 1-57940-142-2. Peart, Neil. Traveling Music: Playing Back the Soundtrack to My Life and Times. ECW Press, 2004. ISBN 1-55022-664-9. Lee, Geddy. Geddy Lee's Big Beautiful Book of Bass. HarperCollins Publishers, 2018. ISBN 9780062747839. Lee, Geddy. My Effin' Life. HarperCollins Publishers, 2023. ISBN 9780063159426
The oxidation step uses oxidised nicotinamide adenine dinucleotide as a cofactor and the enzyme also requires zinc. It belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is 3,4-dihydroxy-L-phenylalanine:oxygen 4,5-oxidoreductase (recyclizing). It participates in tyrosine metabolism.
== See also == All pages with titles containing Link Linc (disambiguation) Lincs (disambiguation) Linker (disambiguation) Linq (disambiguation) Linx (disambiguation) Lynx (disambiguation) Microsoft Lync Linkt, road tolling brand in Australia
Ticks that transmit B. burgdorferi to humans can also carry and transmit several other microbes, such as Babesia microti and Anaplasma phagocytophilum, which cause the diseases babesiosis and human granulocytic anaplasmosis (HGA), respectively. Among people with early Lyme disease, depending on their location, 2–12% will also have HGA and 2–10% will have babesiosis. Ticks in certain regions also transmit viruses that cause tick-borne encephalitis and Powassan virus disease. Co-infections of Lyme disease may not require additional treatment, since they may resolve on their own or—as in the case of HGA—can be treated with the doxycycline prescribed for Lyme. Persistent fever or compatible anomalous laboratory findings may be indicative of a co-infection.
Sources: en.wikipedia.org
The probability of generating false positives means that all interactions should be confirmed by a high confidence assay, for example co-immunoprecipitation of the endogenous proteins, which is difficult for large scale protein–protein interaction data. Alternatively, Y2H data can be verified using multiple Y2H variants or bioinformatics techniques. The latter test whether interacting proteins are expressed at the same time, share some common features (such as gene ontology annotations or certain network topologies), have homologous interactions in other species.
250No In 2003, scientists at the FLNR reported that they had been able to synthesise 249No, which decayed by SF with a half-life of 54 μs. Further work in 2006 by scientists at the ANL showed that the activity was actually due to a K-isomer in 250No. The ground state isomer was also detected with a very short half-life of 3.7 μs.
== Manufacturing == The vaccine candidate can be made in a lyophilized powder form, allowed it to be shipped and stored between 2 and 8 °C (36 and 46 °F). In August 2021, Arcturus Therapeutics entered a partnership with Vinbiocare, a unit of Vingroup to conduct clinical trials of ARCT-154 COVID-19 vaccine, developed created using Arcturus’ STARR mRNA technology, in Vietnam and establish a manufacturing facility a factory in Hòa Lạc Hi-tech Park, Hanoi, which requires an estimated investment of $200 million and has the capacity to make 200 million doses per year. It is expected that Vingroup will produce its first batches of the vaccine in early 2022. Arcturus will provide to Vinbiocare access to "proprietary technologies and processes for the manufacture" of its vaccines, as well as an exclusive license to manufacture them solely for sales and use in Vietnam. This includes all of Arcturus’ other Covid-19 vaccines such as ARCT-021 and other vaccines in the future for disease prevention in Vietnam. Vinbiocare will pay $40m upfront, be responsible for technology transfer costs, and "pay for mRNA drug substance supplied by Arcturus and royalties on vaccines produced at the facility".
Salting is the preservation of food with dry edible salt. It is related to pickling (preparing food with brine, i.e. salty water), and is one of the oldest methods of preserving food. Salt inhibits the growth of microorganisms by drawing water out of microbial cells through osmosis. Concentrations of salt up to 20% are required to kill most species of unwanted bacteria. Smoking, often used in the process of curing meat, adds chemicals to the surface of meat that reduce the concentration of salt required. Salting is used because most bacteria, fungi and other potentially pathogenic organisms cannot survive in a highly salty environment, due to the hypertonic nature of salt. Any living cell in such an environment will become dehydrated through osmosis and die or become temporarily inactivated. The water activity, aw, in a fish is defined as the ratio of the water vapour pressure in the flesh of the fish to the vapour pressure of pure water at the same temperature and pressure. It ranges between 0 and 1, and is a parameter that measures how available the water is in the flesh of the fish. Available water is necessary for the microbial and enzymatic reactions involved in spoilage. There are a number of techniques that have been or are used to tie up the available water or remove it by reducing the aw. Traditionally, techniques such as drying, salting and smoking have been used, and have been used for thousands of years. In more recent times, freeze-drying, water binding humectants, and fully automated equipment with temperature and humidity control have been added.
Sources: en.wikipedia.org
Purity is normally given as a percentage from reversed-phase HPLC, calculated as the main peak area relative to total peak area. Research-grade material is commonly specified at 95 per cent or higher, with tighter specifications available. The number is method-dependent and should be read alongside the chromatogram.
Mass spectrometry is the standard check, comparing the measured mass with the mass calculated from the published amino acid sequence. Retention time on HPLC and peptide mapping provide supporting evidence. Sequence-level confirmation separates it from closely related analogues.
Dry powder is chemically stable enough for freezer storage over long periods. In solution, water participates directly in hydrolysis and enables aggregation, so breakdown accelerates. Cold, dark, short-term storage after dissolution reflects that difference.
It is described as a single molecule that acts at three receptors: the glucose-dependent insulinotropic polypeptide receptor, the glucagon-like peptide-1 receptor, and the glucagon receptor. This triple activity distinguishes it from agents that target one or two of these pathways.