LC-MS/MS 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 2025-09-09. Numbers and descriptions here follow the published literature rather than marketing material.
Development has progressed from single- and multiple-ascending-dose studies in healthy volunteers into larger randomized trials in adults with obesity, type 2 diabetes, and fatty liver disease. Early reports describe dose-dependent reductions in body weight and improvements in glycemic markers over treatment periods of several months. Whether the glucagon arm adds tolerability cost without added benefit is still debated. Long-term cardiovascular outcomes, effects after treatment stops, and performance in older or comorbid populations are open questions rather than settled findings. Approval status may change, so the current investigational label should be confirmed against regulatory sources.
Retatrutide is an investigational synthetic peptide developed under the code LY3437943, with a backbone derived from glucose-dependent insulinotropic polypeptide. Several non-proteinogenic residues, including alpha-aminoisobutyric acid, appear in that backbone, and a fatty diacid side chain attached through a linker extends circulation time. The molecule carries roughly thirty-nine amino acid units and a total mass near 4.7 kilodaltons. Administration is by subcutaneous injection once weekly. Published work uses both the name retatrutide and the code LY3437943.
Pharmacologically the compound activates three receptors: GLP-1, GIP, and glucagon. GLP-1 and GIP signaling contribute to glucose-dependent insulin release, delayed gastric emptying, and reduced appetite, while glucagon receptor activation is associated with increased energy expenditure and hepatic fat oxidation. The single-molecule design is intended to keep these activities in one peptide rather than combining separate agents. Relative activity at each receptor differs, and the balance between them is a central question in interpretation. The glucagon component is partly offset by incretin-mediated insulin secretion, an interaction that remains incompletely characterized.
该分子是经过结构修饰的合成肽，通过脂肪酸侧链与白蛋白结合，从而延长循环时间。皮下给药后，药物逐步释放并分布至组织。降解主要依赖蛋白酶，肾脏清除占次要地位。人体半衰期以天为单位，但准确数值随检测方法和个体差异而变；组织分布与受体占有率仍是开放问题。
临床研究通常测量体重、腰围、空腹血糖、糖化血红蛋白和血脂，并记录不良事件。药代动力学评估关注浓度-时间曲线，药效动力学评估关注代谢标志物变化。体重下降由能量摄入减少、能量消耗变化和脂肪组织重塑共同造成，具体权重仍不明确。研究之间的终点定义和随访时长差异使横向比较复杂。
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide of about 39 residues | Backbone derived from a GIP sequence |
| Molecular mass | Approximately 4.7 kDa | Peptide chain plus fatty diacid moiety |
| Receptor targets | GLP-1, GIP, glucagon | Unimolecular triple agonist |
| Typical storage temperature | 2 to 8 degrees Celsius | Protect from light; avoid repeated freeze-thaw |
| Common analytical method | LC-MS/MS | Used for plasma quantification and purity checks |
稳定性研究一般关注脱酰胺、氧化与聚集三类降解路径。脱酰胺多发生在天冬酰胺残基上，氧化常涉及甲硫氨酸与色氨酸，聚集则与浓度、温度以及容器界面接触有关。强制降解实验用于识别分子中较敏感的位点。这些结果会直接影响储存条件的设定与有效期的判断。
冻干粉通常在低温环境下保存，复溶之后需要按指定条件在较短时间内使用。反复冻融和剧烈振荡可能促进聚集，低吸附容器则能减少多肽在管壁上的损失。批号、日期与处理条件的完整记录，是后续复核与问题追溯的基础。
Several questions remain unresolved. It is not yet known whether the compound reduces cardiovascular events or mortality, because outcome studies require long follow-up. The durability of weight reduction after treatment withdrawal is uncertain, and rebound has been observed with other incretin-based therapies. Long-term safety data covering several years are limited. Effects in adolescents, in pregnancy, and in people with significant kidney or liver impairment have not been characterized in published reports.
Randomized studies of retatrutide measure change in body weight as a percentage of baseline, along with absolute weight loss. Glycemic endpoints include hemoglobin A1c and fasting plasma glucose. Investigators also track blood pressure, lipid fractions, and liver fat content to characterize effects beyond weight alone. Trial designs typically use double-blind, placebo-controlled groups with periodic dose escalation, and they record adverse events throughout both treatment and follow-up periods.
Akt regulates TFEB, a master controller of lysosomal biogenesis, by direct phosphorylation of TFEB at serine 467. Phosphorylated TFEB is excluded from the nucleus and less active. Pharmacological inhibition of Akt promotes nuclear translocation of TFEB, lysosomal biogenesis and autophagy. Akt promotes G1-S phase cell cycle progression by phosphorylating and inactivating glycogen synthase kinase 3 (GSK-3) at Ser9. This prevents the phosphorylation and degradation of cyclin D1.
Epigenetics refers to the study of heritable changes in genetic activities that are distinct from changes in DNA sequences. Epigenetic analysis involves studying DNA-protein interactions, histone modifications, and DNA methylation. Linked-read sequencing has been used for studying DNA methylation patterns by many studies. For example, in 2021, a study investigated the DNA methylation differences in peripheral blood cells between twins, in which one twin had Alzheimer's Disease and the other was cognitively normal. Linked-read sequencing technology allowed researchers to identify more than 3000 differentially methylated regions between these twins discordant for Alzheimer's Disease, and investigation of these differentially methylated regions eventually led to identification of genes enriched in neurodevelopmental processes, neuronal signalling, and immune system functions
Radium's long half-life of 1600 years means that surfaces coated with radium paint, such as watch faces and hands, remain a health hazard long after their useful life is over. There are still millions of luminous radium clock, watch, and compass faces and aircraft instrument dials owned by the public. The case of the "Radium Girls", workers in watch factories in the early 1920s who painted watch faces with radium paint and later contracted fatal cancer through ingesting radium when they pointed their brushes with their lips, increased public awareness of the hazards of radioluminescent materials, and radioactivity in general.
it is indicated in the treatment of adults who are unable to achieve sufficient glycaemic control at their maximally tolerated dose of oral metformin alone or who are already treated with the combination of vildagliptin and metformin as separate tablets. it is indicated in combination with a sulphonylurea (i.e. triple combination therapy) as an adjunct to diet and exercise in patients inadequately controlled with metformin and a sulphonylurea. it is indicated in triple combination therapy with insulin as an adjunct to diet and exercise to improve glycaemic control in patients when insulin at a stable dose and metformin alone do not provide adequate glycaemic control.
Sources: en.wikipedia.org
After basic cell counting had been automated, the white blood cell differential remained a challenge. Research into automating the differential count began in the 1970s and took two main approaches: digital image processing and flow cytometry. Using technology developed in the 1950s and 60s to automate the reading of Pap smears, several models of image processing analyzers were produced. These instruments would scan a stained blood smear to find cell nuclei, then take a higher resolution snapshot of the cell to analyze it through densitometry. They were expensive, slow, and did little to reduce workload in the laboratory because they still required blood smears to be prepared and stained, so flow cytometry-based systems became more popular, and by 1990, no digital image analyzers were commercially available in the United States or western Europe. These techniques enjoyed a resurgence in the 2000s with the introduction of more advanced image analysis platforms using artificial neural networks. Early flow cytometry devices shot beams of light at cells in specific wavelengths and measured the resulting absorbance, fluorescence or light scatter, collecting information about the cells' features and allowing cellular contents such as DNA to be quantified. One such instrument—the Rapid Cell Spectrophotometer, developed by Louis Kamentsky in 1965 to automate cervical cytology—could generate blood cell scattergrams using cytochemical staining techniques.
==== Smalley source ==== A laser vaporization cluster source produces ions using a combination of laser desorption ionization and supersonic expansion. The Smalley source (or Smalley cluster source) was developed by Richard Smalley at Rice University in the 1980s and was central to the discovery of fullerenes in 1985.
== History == The US Food and Drug Administration (FDA) approved serdexmethylphenidate/dexmethylphenidate based on evidence from one clinical trial of 150 participants with attention deficit hyperactivity disorder 6 to 12 years of age (Study 1). The four-week trial was conducted at five sites in the United States. The safety and tolerability of serdexmethylphenidate/dexmethylphenidate was examined in an open-label trial of 238 participants with attention deficit hyperactivity disorder 6 to 12 years of age (Study 2). The 12-month trial was conducted at 18 sites in the United States.
11 May A logic gate for computation at femtosecond timescales is demonstrated. A study shows that infusing the nourishing cerebrospinal fluid from around brain cells of young mice into aged brains rejuvenates aspects of the brain, identifying FGF17 as a key target for potential therapeutics such as of anti-aging. Scientists close a missing link in the potential origin of life from a RNA world – synergistic formation of peptides and ever-longer RNAs or peptide-decorated RNA, leading to a protein world. A study suggests that in children at age 8–12 during two years, time gaming or watching digital videos can be positively correlated with measures intelligence, albeit correlations with overall screen time (including social media, socializing and TV) were not investigated and 'time gaming' did not differentiate between categories of video games (e.g. shares of games' platform and genre). 12 May Sagittarius A*, the supermassive black hole at the center of the Milky Way galaxy, is imaged for the first time by the Event Horizon Telescope team. Researchers report that lunar soil has been used to grow plants for the first time. Researchers identify the 425 biggest fossil fuel extraction projects globally, of which 40% as of 2020 are new projects that haven't yet started extraction. They conclude that "defusing" these "carbon bombs" – worked on by only "few actors" to date – would be necessary for climate change mitigation of global climate goals.
Compound characterization with TLC is also possible and is similar to reaction monitoring. However, rather than spotting with starting material and reaction mixture, it is with an unknown and a known compound. They may be the same compound if both spots have the same RF and look the same under the chosen visualization method. However, co-elution complicates both reaction monitoring and characterization. This is because different compounds will move to the same spot on the plate. In such cases, different solvent mixtures may provide better separation.
Sources: en.wikipedia.org
=== The Fish Farmers clan === The Fish Farmers clan (Dutch: De Visboeren) are led by the owners of the well-known fishmonger De Antwerpse Visser in the districts of Borgerhout and Kiel in Antwerp. The organisation is led by the brothers Mohamed A., Rachid A. and Hassan A., who quickly established themselves as main contributors within the international cocaine trade. They established the organisation in the early 2010s and took control over the cocaine trade throughout Flanders. Dozens of containers from Colombian cartels were trafficked through the organisation of the Fish Farmers clan. They very quickly competed against other organisations within the Moroccan mafia. In 2018, the Kali-team (an anti-Moroccan mafia police unit from Antwerp) discovered that the Fish Farmers were amongst the main owners of a luxury suite in the Hilton hotel near the Tangier-Ville railway station in Morocco. In March 2020, the three brothers and their father Mohamed (73) were sentenced up to eight years in prison.
A potential issue that arises through the use of NMR is low mass sensitivity, however this can be corrected for by employing microcoils that assist in distinguishing molecules of differing masses. This is necessary since the signal-to-noise ratio of sample sizes in the microliter to nanoliter range is dramatically reduced compared to bench-scale sample sizes, and microcoils have been shown to resolve this issue. Mass spectrometry (MS) and high-performance liquid chromatography (HPLC) have also been used to overcome this challenge. Although MS is an attractive analytical technique for distinguishing the products of reactions accomplished through DMF, it poses its own weaknesses. Matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) MS have recently been paired with analyzing microfluidic chemical reactions. However, crystallization and dilution associated with these methods often leads to unfavorable side effects, such as sample loss and side reactions occurring. The use of MS in DMF is discussed in more detail in a later section.
Atmospheric pressure is variable but 101.325 and 100 kilopascals (1013.25 and 1000.00 mbar) are common standard or reference pressures. Deep space is generally much more empty than any artificial vacuum. It may or may not meet the definition of high vacuum above, depending on what region of space and astronomical bodies are being considered. For example, the MFP of interplanetary space is smaller than the size of the Solar System, but larger than small planets and moons. As a result, solar winds exhibit continuum flow on the scale of the Solar System, but must be considered a bombardment of particles with respect to the Earth and Moon. Perfect vacuum is an ideal state of no particles at all. It cannot be achieved in a laboratory, although there may be small volumes which, for a brief moment, happen to have no particles of matter in them. Even if all particles of matter were removed, there would still be photons, as well as dark energy, virtual particles, and other aspects of the quantum vacuum.
The American film critic Pare Lorentz defines a documentary film as "a factual film which is dramatic." Others further state that a documentary stands out from the other types of non-fiction films for providing an opinion, and a specific message, along with the facts it presents. Scholar Betsy McLane asserted that documentaries are for filmmakers to convey their views about historical events, people, and places which they find significant. Therefore, the advantage of documentaries lies in introducing new perspectives which may not be prevalent in traditional media such as written publications and school curricula. Documentary practice is the complex process of creating documentary projects. It refers to what people do with media devices, content, form, and production strategies to address the creative, ethical, and conceptual problems and choices that arise as they make documentaries. Documentary filmmaking can be used as a form of journalism, advocacy, or personal expression.
=== Smoking cessation === Cytisine has been available in post-Soviet states as an aid to smoking cessation under the brand name Tabex from the Bulgarian pharmaceutical company Sopharma AD. In 1961, Bulgarian pharmacist Strashimir Ingilizov synthesized Tabex using the alkaloid Cytisine which was derived from the seeds of the yellow acacia (Cytisus laburnum), a European decorative shrub prevalent in Bulgaria and commonly referred to as "golden rain". It was first marketed in Bulgaria in 1964 and then became widely available in the Soviet Union. In Poland, it is sold under the brand name Desmoxan, and it is also available in Canada under the brand name Cravv. In June 2026, the U.S. Food and Drug Administration issued a complete response letter for Achieve Life Sciences' application to market cytisinicline for smoking cessation, citing deficiencies at a third-party manufacturing facility and unfinished product labeling. Its molecular structure has some similarity to that of nicotine, and it has similar pharmacological effects. Like the smoking cessation aid varenicline, cytisine is a partial agonist of nicotinic acetylcholine receptors (nAChRs). Cytisine has a short half-life of 4.8 hours. As a result, the extract provides smokers with satisfaction similar to smoking a cigarette, alleviating the urge to smoke and reducing the severity of nicotine withdrawal symptoms, while also reducing the reward experience of any cigarettes smoked.
Sources: en.wikipedia.org
As of the mid-2020s retatrutide remains investigational and is not an approved medicine in the United States or the European Union. It has been supplied mainly to participants in clinical trials. Labels and availability can change, so regulatory listings should be checked directly.
Dual agonists act at the GLP-1 and GIP receptors, whereas retatrutide adds glucagon receptor activity on the same peptide. This third activity is the main structural and pharmacological distinction discussed in the literature. Direct head-to-head comparisons remain limited.
Reports usually give the study code LY3437943 alongside the name, the dose in milligrams, and the week at which an endpoint was measured. Percent body-weight change is the most frequent headline measure. Units and populations vary, so comparisons across reports require care.
意味着单个分子可同时结合三种代谢受体，而不是只作用于一种。其目的是整合食欲、胰岛素和能量消耗通路，但人体中的协同程度仍在研究。