melanocortin receptor comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-05-05. Where a claim depends on a specific study, the study is described rather than over-claimed.
Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.
Research interest has centred on photoprotection and pigmentation, with a smaller body of work on appetite and sexual function. Published human data remain limited to small, frequently uncontrolled studies, and the compound has never received marketing approval from a national medicines regulator. Most laboratory work treats it as a pharmacological tool for probing melanocortin signalling in cell culture or animal models. Whether pigmentation changes observed in people translate into measurable protection against ultraviolet-induced DNA damage remains an open question.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Melanotan II; MT-II; N-acetyl-norleucyl-cyclo[Asp-His-D-Phe-Arg-Trp-Lys] amide | Naming follows peptide convention; the numeral distinguishes it from melanotan-1 |
| Molecular formula | C50H69N15O9 | Includes the lactam bridge; no counter-ion assumed |
| Monoisotopic mass | 1023.53 Da | Free base; salts and counter-ions shift the observed value |
| Appearance | White to off-white lyophilised powder | Batch-to-batch colour variation is not itself proof of impurity |
| Typical analytical method | RP-HPLC purity determination with ESI-MS identity confirmation | Retention time alone does not establish sequence identity |
=== Asexual === All known cnidarians can reproduce asexually by various means, in addition to regenerating after being fragmented. Hydrozoan polyps only bud, while the medusae of some hydrozoans can divide down the middle. Scyphozoan polyps can both bud and split down the middle. In addition to both of these methods, Anthozoa can split horizontally just above the base. Asexual reproduction makes the daughter cnidarian a clone of the adult. The ability of cnidarians to asexually reproduce ensures a greater number of mature medusa that can mature to reproduce sexually.
=== Characters and setting === Decay is set in the same location and timeframe as Half-Life. Half-Life takes place at a laboratory called the Black Mesa Research Facility, situated in a remote desert in New Mexico. In Half-Life, the player takes on the role of Gordon Freeman, a scientist involved in an accident that opens an inter-dimensional portal to the borderworld of Xen, allowing the alien creatures of Xen to attack the facility. The player guides Freeman in an attempt to escape the facility and close the portal, ultimately traveling to Xen to do so. Like the previous expansions, Decay shows the story of Half-Life from the perspective of a different set of protagonists. In Decay, players assume the roles of Colette Green and Gina Cross, two doctors who work in the same labs as Freeman, analyzing anomalous materials and specimens retrieved from Xen in prior teleportation experiments. After the experiment that causes the alien invasion takes place, Green and Cross must work with two ranking members of the science team, Dr. Richard Keller and Dr. Rosenberg, to contain and stabilize the deteriorating situation in Black Mesa.
== Selective ligands == A range of selective ligands for the GHS-R receptor are now available and are being developed for several clinical applications. GHS-R agonists have appetite-stimulating and growth hormone-releasing effects, and are likely to be useful for the treatment of muscle wasting and frailty associated with old-age and degenerative diseases. On the other hand, GHS-R antagonists have anorectic effects and are likely to be useful for the treatment of obesity.
== Sovereign Principality of the United Netherlands (1813–1815) == Following the collapse of the Napoleonic regime, and allied forces drove out the French in 1813, the Dutch called back William Frederick, the son of the last stadtholder William V, to head the new government. He was proclaimed "sovereign prince" and the country briefly existed as the Sovereign Principality of the United Netherlands.
Neuroanatomical studies support that autism may involve abnormal neuronal growth and pruning, leading to brain enlargement in some areas and reduction in others. Functional neuroimaging studies show reduced activation in somatosensory cortices during theory of mind tasks in autistic individuals and highlight potential imbalances in neurotransmitters like glutamate and Γ-aminobutyric acid that may underlie autism's behavioural manifestations.
Sources: en.wikipedia.org
== SARS-CoV-2 proofreading enzyme == Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the COVID-19 pandemic. The SARS-CoV-2 RNA virus genome encodes a replication-and transcription complex, a multisubunit protein machine that carries out viral genome replication and transcription, processes essential to the virus life cycle. One of the proteins specified by the coronavirus genome is a non-structural protein, nsp14, that is a 3'-to-5' exoribonuclease (ExoN). This protein resides in the protein complex nsp10-nsp14 that enhances replication fidelity by proofreading RNA synthesis, an activity critical for the virus life cycle. Furthermore, the coronavirus proofreading exoribonuclease nsp14-ExoN is required for maintaining genetic recombination generated during infection.
That's exactly what I didn't want to happen." One of Staley's last shows with Alice in Chains was the MTV Unplugged performance in New York on April 10, 1996. The recording of Unplugged came after a long period of inactivity for the band; it was their first concert in two-and-a-half years. Staley made his last performance on July 3, 1996, in Kansas City, Missouri, while Alice in Chains was touring with Kiss.
Omaveloxolone, sold under the brand name Skyclarys, is a medication used for the treatment of Friedreich's ataxia. It is taken by mouth. The most common side effects include an increase in alanine transaminase and an increase of aspartate aminotransferase, which can be signs of liver damage, headache, nausea, abdominal pain, fatigue, diarrhea and musculoskeletal pain. Omaveloxolone was approved for medical use in the United States in February 2023, and in the European Union in February 2024. The US Food and Drug Administration (FDA) considers it to be a first-in-class medication.
==== United Kingdom ==== From October 2011 as part of the Modernising Scientific Careers scheme, the route to accreditation as a medical physicist in England and Wales is provided by the Scientist Training Programme (STP). This scheme is a three-year graduate program provided by the National School of Healthcare Science. Entrants are required to have an undergraduate degree (first or upper second class honours) in an appropriate physical science prior to this three-year graduate program. The STP involves a part-time MSc in Medical Physics (provided by either King's College London, University of Liverpool or Newcastle University) in addition to practical training within the National Health Service. Assessment is provided by the completion of competencies and by a final assessment similar to the OSCE undertaken by other clinical staff. Completion of the STP leads to accreditation by the Institute of Physics and Engineering in Medicine (IPEM) and registration as a Clinical Scientist with the Health and Care Professions Council (HCPC). Prior to 2011 the training route in the United Kingdom was administered in two parts, and this scheme is still used in Scotland (known as the Scottish Medical Physics and Clinical Engineering Training Scheme (SMPCETS)). Part I involves limited clinical experience and a full-time MSc in medical physics. Part II involves exclusively clinical experience in which the candidate would produce a portfolio of experience and submit to the Academy for Healthcare Science which (in addition to a viva) would lead to professional accreditation by IPEM.
Sources: en.wikipedia.org
== History == Phencyclidine was initially discovered in 1926 by Arthur Kötz and his student Paul Merkel as a product of a Grignard reaction of 1-piperidinocyclohexancarbonitrile. It was again synthesized in 1956 by chemist H Victor Maddox and brought to market as an anesthetic medication by pharmaceutical company Parke-Davis, now a subsidiary of Pfizer. Its use in humans was disallowed in the US in 1965 due to the high rates of side effects, while its use in animals was disallowed in 1978. Moreover, ketamine was discovered and was better tolerated as an anesthetic. PCP is classified as a schedule II drug in the US. Derivatives of PCP have been sold for recreational and non-medical use.
== History == Two main studies showed that treosulfan is at least as effective as busulfan, another medicine used to prepare people for haematopoietic stem cell transplantation. In one of the studies, involving 570 adults with acute myeloid leukaemia (a blood cancer) or myelodysplastic syndromes (conditions in which large numbers of abnormal blood cells are produced), 64% of patients given treosulfan (with fludarabine) had a successful transplant and were alive and disease-free after 2 years, compared with 51% of patients given busulfan (with fludarabine). In an additional study in 70 children with blood cancers, 99% of children given treosulfan (with fludarabine) were alive three months after their transplant. Efficacy was evaluated in MC-FludT.14/L Trial II (NCT00822393), a randomized active-controlled trial comparing treosulfan to busulfan with fludarabine as a preparative regimen for allogeneic transplantation. Eligible patients included adults 18 to 70 years old with AML or MDS, Karnofsky performance status ≥ 60%, and age ≥ 50 years or hematopoietic cell transplantation comorbidity index [HCTCI] score > 2. There were 570 patients randomized to treosulfan (n=280) or busulfan (n=290).
These processes are increasingly aligned although important differences remain and drug developers must prepare separate documents. New development pathways have been developed to help with the approval of new antimicrobial agents that address unmet needs such as the Limited Population Pathway for Antibacterial and Antifungal Drugs (LPAD). These new pathways are required because of difficulties in conducting large definitive phase III clinical trials in a timely way. Some of the economic impediments to the development of new antimicrobial agents have been addressed by reimbursement schemes that delink payment of antimicrobials from volume-based sales. In the UK, a market entry reward scheme has been pioneered by the National Institute for Clinical Excellence (NICE) whereby an annual subscription fee is paid for use of strategically valuable antimicrobial agents – cefiderocol and ceftazidime-aviabactam are the first agents to be used in this manner and the scheme is potential blueprint for comparable programs in other countries. The available classes of antifungal drugs are still limited but as of 2021 novel classes of antifungals are being developed and are undergoing various stages of clinical trials to assess performance. Scientists have started using advanced computational approaches with supercomputers for the development of new antibiotic derivatives to deal with antimicrobial resistance.
==== Peripheral nervous system ==== Eight to ten nerves arise from the cerebral ganglia to supply the prostomium, buccal chamber and pharynx. Three pairs of nerves arise from the subpharyngeal ganglia to supply the second, third and fourth segment. Three pairs of nerves extend from each segmental ganglion to supply various structures of the segment. The sympathetic nervous system consists of nerve plexuses in the epidermis and alimentary canal. The nerves that run along the body wall pass between the outer circular and inner longitudinal muscle layers of the wall. They give off branches that form the intermuscular plexus and the subepidermal plexus. These nerves connect with the cricopharyngeal connective.
== Terminology == A supply involves the procurement, distribution, maintenance while in storage, and salvage of supplies, including the determination of kind and quantity of supplies. United States Department of Defense definitions refer to a "producer phase" and a "consumer phase":
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, containing seven amino acids with a lactam ring and a D-configured phenylalanine residue. It is supplied as a lyophilised powder for laboratory research.
The natural hormone is a linear tridecapeptide that is rapidly degraded in circulation. Melanotan-2 is shortened, cyclised, N-terminally acetylated, and carries a D-amino acid substitution, all of which slow enzymatic breakdown.
No national medicines regulator has approved melanotan-2 for therapeutic or cosmetic use. In several jurisdictions it is treated as an unapproved prescription medicine, and its legal classification differs from country to country.
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.