anti-doping raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-03-12 and is reviewed periodically as new material appears.
SR9009 is not approved as a medicine by major regulatory agencies. It is commonly sold as a research chemical, a category that may fall outside customary drug approval and quality rules. In sports, the World Anti-Doping Agency lists SR9009 as a prohibited substance. Athletes who use it can face sanctions if it is detected in a sample. Legal status varies by country, and importation may be restricted. Enforcement practices differ across borders.
Detection of SR9009 in biological samples usually employs liquid chromatography coupled with tandem mass spectrometry. This method can identify the parent compound and sometimes metabolites in urine or blood. Because exposure can be low and clearance may be rapid, sample timing and limits of detection matter. Laboratories validate assays for sensitivity and specificity. Results are interpreted alongside chain-of-custody and quality-control records. Urine is the common matrix for anti-doping analysis, while blood may be used in research settings.
Handling recommendations for SR9009 in a laboratory setting include storing the solid at low temperature, protected from light and moisture. The compound is often dissolved in dimethyl sulfoxide or ethanol for experiments. Solutions should be prepared with appropriate personal protective equipment and disposed of according to local rules. Stability data for long-term storage are limited, so stock solutions are typically kept cold and used within defined periods. Records of preparation date and concentration support reproducibility.
SR9009 is a synthetic small molecule that acts on the nuclear receptors REV-ERBα and REV-ERBβ. These receptors are part of the circadian clock machinery and normally repress transcription of certain target genes. In laboratory research, SR9009 is used as a chemical tool to study how REV-ERB activity influences metabolism, inflammation, and daily biological rhythms. The compound is not an approved medicine, and its effects in humans remain largely uncharacterized. It is often described as an investigational agent rather than a therapeutic product.
REV-ERB proteins typically suppress gene expression by recruiting corepressor complexes to DNA response elements. SR9009 binds these receptors and strengthens that repressive action in cell-based assays. Studies in rodents have reported changes in lipid handling, mitochondrial function, and exercise capacity after treatment. Such findings are often cited as evidence for metabolic effects, but species differences and limited pharmacokinetic data make direct translation to humans uncertain. Researchers continue to examine which effects are robust and which depend on specific experimental conditions.
| Property | Value | Notes |
|---|---|---|
| Regulatory status | Not approved as a medicine in major jurisdictions | Sold as a research chemical; legal status varies |
| Anti-doping status | Prohibited by the World Anti-Doping Agency | Listed under non-approved substances or related category |
| Typical analytical method | LC-MS/MS | Used for detection and confirmation in biological samples |
| Storage temperature | −20 °C or lower for solid | Desiccated and protected from light |
| Common solution solvents | DMSO; ethanol | Aqueous solubility is limited |
SR9009 is a synthetic small molecule studied as an agonist of the nuclear receptors REV-ERBα and REV-ERBβ. These receptors help regulate circadian rhythms and metabolic gene expression. In laboratory experiments, SR9009 binds these receptors and alters transcription of genes involved in lipid handling, glucose metabolism, and mitochondrial function. It is not a naturally occurring compound and has no approved therapeutic use. Research interest stems from its ability to modify energy metabolism in cells and animal models.
In rodent studies, SR9009 has been reported to increase mitochondrial content in skeletal muscle and improve exercise endurance under some conditions. These findings led to popular descriptions such as an exercise mimetic, although that term oversimplifies the biology. Effects vary by dose, timing, tissue, and model. The compound's influence on circadian pathways means that time of administration can matter in experiments. Whether similar metabolic changes occur in humans remains largely unexplored in controlled published trials.
Analytical identification and purity assessment often use high-performance liquid chromatography with ultraviolet detection or mass spectrometry. Liquid chromatography–tandem mass spectrometry is used to detect and quantify SR9009 in biological matrices, including urine and blood, for anti-doping or pharmacokinetic studies. Nuclear magnetic resonance spectroscopy can confirm molecular structure. Stability depends on form and storage: the solid is generally more stable than solutions, and repeated freeze–thaw cycles may degrade samples. Purity is typically reported as a percentage from a certificate of analysis.
Regulatory treatment of SR9009 varies by country and context. It is not approved as a therapeutic drug by agencies such as the United States Food and Drug Administration or the European Medicines Agency. Sports authorities list it as a prohibited substance; the World Anti-Doping Agency classifies it among hormone and metabolic modulators. Legal status for personal possession or sale differs across jurisdictions, and some countries may restrict it under analog or research chemical laws. Buyers who seek verified material often rely on independent laboratory testing because online product labels may not match contents.
Analytical chemists detect SR9009 with liquid chromatography-tandem mass spectrometry, commonly abbreviated LC-MS/MS. Sample preparation may involve protein precipitation, liquid-liquid extraction, or solid-phase extraction before analysis. Laboratories can target the parent compound or its metabolites, depending on the matrix and the purpose of testing. Anti-doping methods require sensitive and specific assays because concentrations in biological samples can be low. Reference standards and validated methods are essential for reliable identification and quantification.
Regulatory agencies have not approved SR9009 for human therapeutic use. It is typically sold as a research chemical with labels stating that it is not for human consumption. The World Anti-Doping Agency prohibits the substance in sport, generally under the category of non-approved substances. Customs and national laws may restrict importation, sale, or possession. Product quality and legal status can vary by country and vendor, and therapeutic claims are not permitted in regulated advertising because the compound lacks approval.
Several misconceptions surround SR9009. It is often described as a SARM, a steroid, or an exercise pill, but its known target is the REV-ERB receptor family. Rodent studies have examined exercise capacity and metabolic markers, yet human outcomes remain unproven. Oral bioavailability appears low in animals, and human pharmacokinetics are not well characterized. Online products may contain impurities or different compounds, so identity and purity testing are important for research use.
Profilins are proteins of molecular weights of roughly 14–19 kDa. They are present as single genes in yeast, insects, and worms, and as multiple genes in many other organisms including plants. In mammalian cells, four profilin isoforms have been discovered; profilin-I is expressed in most tissues while profilin-II is predominant in brain and kidney. Asgard archaea use profilins. Multiple eukaryotic diatom species lack profilins. Profilin is essential to host cell invasion by Toxoplasma gondii. Toxoplasma profilin is the specific pathogen-associated molecular pattern (PAMP) of TLRs 5, 11, and 12. Profilin enhances actin growth in two ways:
Klibanski became chief of the Neuroendocrine Unit at Massachusetts General Hospital, studying hormones and neuroendocrinology with a focus on hypopituitarism and pituitary tumors. Her clinical research has also examined the effects of hypothalamic and pituitary disorders on body composition and bone density, including bone loss associated with anorexia nervosa and growth hormone deficiency. In 1997, Klibanski became the first woman from Mass General's Department of Medicine to become a professor of medicine at Harvard. She has authored more than 350 peer-reviewed papers and book chapters and has received the Endocrine Society Clinical Investigator Award and the Clinical Endocrinology Trust Medal from the Society for Endocrinology. Klibanski has served on the National Institute of Diabetes and Digestive and Kidney Diseases Board of Counselors and the editorial board of the Journal of Clinical Endocrinology and Metabolism, and is a past president of the Pituitary Society. She established the Center for Faculty Development at Massachusetts General Hospital and mentored more than fifty women, for which she received the Endocrine Society's Outstanding Mentor Award.
The ISOLDE facility contains the Class A laboratories, buildings for the HIE-ISOLDE and MEDICIS projects, and the control rooms located in building 508. Before ISOLDE, the radioactive nuclides were transported from the production are to the laboratory for examination. At ISOLDE, all processes from the production to the measurements are connected and the radioactive material requires no extra transport. Due to this, ISOLDE is referred to as an on-line facility. At the ISOLDE facility, the main proton beam for reactions comes from the PSB. The incoming proton beam has an energy of 1.4 GeV and its average intensity varies up to 2 μA. The beam enters the facility and is directed towards one of two mass separators: the General Purpose Separator (GPS) and the High Resolution Separator (HRS). The separators have independently run target-ion source systems, delivering 60 keV RIBs.
Sources: en.wikipedia.org
81. ArXiv [Preprint]. 2026 Jul 29:arXiv:2605.17186v2. Operator splitting for exploiting linear-rate closure in solving infinite ODE hierarchies. Chang JC. We introduce an operator-splitting method for infinite hierarchies of linear ordinary differential equations (ODEs) indexed by nonnegative integers. When the coupling coefficients depend linearly on the count index, an exact transformation closes the equations on finite count-index windows without an upper-boundary value. For more general hierarchies, Strang splitting applies the linear-rate closure during the linear-rate substeps and a conventional capped solver to the remainder. We derive the closure from generating functions and the method of characteristics and extend it to multi-indexed systems. The derivation requires neither positivity nor mass conservation, so it applies to a wider class of systems than the examplar stochastic models presented here. We discuss branching processes, stochastic predator-prey dynamics, the Schlögl chemical kinetics model, and a telegraph model for gene expression. Through numerical experiments and computational cost analyses we demonstrate that our operator splitting method is typically advantageous for solving large scale systems in terms of memory usage and computational time, while retaining accuracy competitive with finite state projection (FSP) methods. PMCID: PMC13618430
Mike Evans tied the record for consecutive seasons with at least 1,000 receiving yards, with 11. He shares this record with Jerry Rice. Evans also extended his own record of most such seasons to start his career. Aaron Rodgers became the fifth player to have 500 passing touchdowns. Trey McBride set the record for most receptions by a tight end in his first three seasons, with 221. The previous record of 216 was held by George Kittle. The Buffalo Bills became the first team to score at least 30 rushing touchdowns and at least 30 passing touchdowns in a season. Wild Card Round
Intussusceptive angiogenesis, also known as splitting angiogenesis, is the formation of a new blood vessel by splitting an existing blood vessel into two. Intussusception was first observed in neonatal rats. In this type of vessel formation, the capillary wall extends into the lumen to split a single vessel in two. There are four phases of intussusceptive angiogenesis. First, the two opposing capillary walls establish a zone of contact. Second, the endothelial cell junctions are reorganized and the vessel bilayer is perforated to allow growth factors and cells to penetrate into the lumen. Third, a core is formed between the 2 new vessels at the zone of contact that is filled with pericytes and myofibroblasts. These cells begin laying collagen fibers into the core to provide an extracellular matrix for growth of the vessel lumen. Finally, the core is fleshed out with no alterations to the basic structure. Intussusception is important because it is a reorganization of existing cells. It allows a vast increase in the number of capillaries without a corresponding increase in the number of endothelial cells. This is especially important in embryonic development as there are not enough resources to create a rich microvasculature with new cells every time a new vessel develops.
Sources: pubmed.ncbi.nlm.nih.gov
Its legal status depends on the country and intended use. It is not an approved medicine in major jurisdictions. In sport, it is prohibited by anti-doping rules.
Laboratories typically use LC-MS/MS to detect SR9009 and related compounds in urine or blood. The method is sensitive but depends on sample collection timing. Confirmatory analysis follows quality-control procedures.
Solid material is generally kept cold, dry, and protected from light. Solutions are often stored in sealed containers at low temperature. Stability beyond recommended periods is not well documented.
SR9009 is a synthetic research compound that binds and modulates the nuclear receptors REV-ERBα and REV-ERBβ. It is used in laboratory studies of circadian biology and metabolism, not as an approved medicine. It is also known by the informal name Stenabolic.