The short version of cyclic heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
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Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Alpha-MSH analogue with a lactam ring |
| Molecular formula | C50H69N15O9 | Commonly cited value for the neutral peptide |
| Molecular weight | 1024.18 g/mol | Calculated for the free molecule |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water, DMSO and ethanol | Dissolution in pure water is often slow |
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
==== Thousand-layer tofu ==== Thousand-layer tofu (simplified Chinese: 千叶豆腐; traditional Chinese: 千葉豆腐; pinyin: qiānyè dòufu; lit. 'thousand-layer tofu') is not a true tofu made by coagulation of soymilk, but a modern invention made from soy protein isolate and a source of starch. It has a smooth, bouncy texture somewhat comparable to kamaboko. Originally a Taiwanese invention called hundred-layer tofu (百葉豆腐), it was renamed in China to avoid confusion with the existing type of extra-firm tofu called baiye.
=== Mass spectrometry === Quantitative mass spectrometry (MS) (or quantitative proteomics) can be used to discover RNA-binding proteins (RBPs) bound to RNA. Labeling MS methods involve the differential use of stable isotope labels or chemical tagging of proteins in samples and controls. This is used to obtain enrichment scores and true binding partners through the ratio of labeled peptides. Label-free MS methods are able to identify proteins in samples and controls. In order to distinguish true binding partners for nonspecific proteins, analytical tools used alongside spectral count data from non-quantitative MS are used to score the probability of a true RBP-RNA interaction
== Career == In December 1986, Cameron joined the Department of Chemical Engineering at the University of Wisconsin—Madison, as an assistant professor and advanced to full professor. The focus of his research was metabolic engineering (a field now more commonly known as synthetic biology) and industrial microbiology. One of his first projects was the engineering of the microbial pathway for 1,3-propanediol in Escherichia coli. This work was an early step in a process that was eventually commercialized by DuPont and Tate & Lyle. He is also the inventor of a process for the microbial production of 3-hydroxypropionic acid, which provides a bio-based route to industrial chemicals such as acrylic acid. In 1996 he did a sabbatical at the ETH Zurich (Switzerland) in the laboratory of James (Jay) E. Bailey. In 1998 he took a leave of absence to start the Biotechnology Development Center (BioTDC) at Cargill, Inc. in Minneapolis. In 2000 he officially left the University of Wisconsin. Cameron was at Cargill, Inc. from 1998 to 2006, where he was Director of Biotechnology and chief scientist. While at Cargill he worked closely with NatureWorks on the development of a low-pH process for lactic acid as a feedstock for polylactic acid. He and his team also worked with Cargill Ventures on deal-sourcing and due-diligence. In June 2006, Cameron moved from Cargill to join the newly formed Silicon Valley venture capital firm, Khosla Ventures, as chief scientific officer. In 2008, Cameron returned to the Midwest to help Piper Jaffray build and grow its clean tech investment business.
==== Erect ==== Scientific studies have been performed on the erect length of the adult penis. Studies that have relied on self-measurement, including from Internet surveys, consistently reported a higher average length than those that used medical or scientific methods to obtain measurements.
Sources: en.wikipedia.org
==== Quantum dot with nanowire in solar cells ==== Another potential use involves capped single-crystal ZnO nanowires with CdSe quantum dots, immersed in mercaptopropionic acid as hole transport medium in order to obtain a QD-sensitized solar cell. The morphology of the nanowires allowed the electrons to have a direct pathway to the photoanode. This form of solar cell exhibits 50–60% internal quantum efficiencies. Nanowires with quantum dot coatings on silicon nanowires (SiNW) and carbon quantum dots. The use of SiNWs instead of planar silicon enhances the antiflection properties of Si. The SiNW exhibits a light-trapping effect due to light trapping in the SiNW. This use of SiNWs in conjunction with carbon quantum dots resulted in a solar cell that reached 9.10% PCE. Graphene quantum dots have also been blended with organic electronic materials to improve efficiency and lower cost in photovoltaic devices and organic light emitting diodes (OLEDs) compared to graphene sheets. These graphene quantum dots were functionalized with organic ligands that experience photoluminescence from UV–visible absorption.
==== Afonso Dias' acquittal ==== "The silence of Afonso Dias made us think of the worse. The only explanation that I find for him to continue to not talk is that he is hiding something even worse than what is being discussed. (...) Afonso has the legal right of being silent, but not the moral right (...) He still has time to regret. We have the remote hope that Afonso Dias comes to his senses as a man and says what happened." - Ricardo Sá Fernandes, 2012In Dias' trial, the following facts were given as proven by the judge Carla Fraga: In the day of Mendonça's disappearance, a man introduced an 11-year-old boy to the prostitute, Alcina Dias. According to the court's hypothesis, it could have been another man and another boy. Mendonça got in Dias' car and left his bike next to the meeting place. Seven witnesses confirmed that Mendonça had two meetings with Dias. Dias was going to introduce Mendonça and João André Mendonça to the prostitutes. However, the court said it was not proven that Dias had formulated a plan for Mendonça to have sexual relations with the prostitutes. Dias ordered that João André Mendonça did not tell anyone about the invitation that he made to meet with the prostitutes, as he was afraid of "becoming a suspect." Such proven facts did not avoid the defendant's acquittal in March 2012.
What Is the Heart? – NIH Atlas of Human Cardiac Anatomy Dissection review of the anatomy of the Human Heart including vessels, internal and external features Prenatal human heart development Animal hearts: fish, squid The Heart, BBC Radio 4 interdisciplinary discussion with David Wootton, Fay Bound Alberti & Jonathan Sawday (In Our Time, 1 June 2006) "Heart" . Encyclopædia Britannica. Vol. 13 (11th ed.). 1911. pp. 129–134.
==== Antigen-independent theories ==== Antigen-independent theories refer to the biochemical properties of HLA-B27. The misfolding hypothesis suggests that slow folding during HLA-B27's tertiary structure folding and association with β2 microglobulin causes the protein to be misfolded, initiating the unfolded protein response (UPR), a pro-inflammatory endoplasmic reticulum (ER) stress response. Although this mechanism has been demonstrated in vitro and in animals, there is little evidence of its occurrence in human spondyloarthritis. The HLA-B27 heavy chain homodimer formation hypothesis suggests that B27 heavy chains tend to dimerise and accumulate in the ER, initiating the UPR. Cell surface B27 heavy chains and dimers can bind to regulatory immune receptors such as members of the killer cell immunoglobulin-like receptor family, promoting the survival and differentiation of pro-inflammatory leukocytes in disease. Another misfolding theory published in 2004 proposes that β2 microglobulin-free heavy chains of HLA-B27 undergo a facile conformational change in which the C-terminal end of domain two, consisting of a long helix, becomes subject to a helix-coil transition involving residues 169–181 of the heavy chain, owing to the conformational freedom newly experienced by domain three of the heavy chain when there is no longer any bound light chain, and owing to the consequent rotation around the backbone dihedral angles of residues 167/168.
=== Self-assembly by molecular interactions === Nanoparticles have the ability to assemble chemically through covalent or noncovalent interactions with their capping ligand. The terminal functional group(s) on the particle are known as capping ligands. As these ligands tend to be complex and sophisticated, self-assembly can provide a simpler pathway for nanoparticle organization by synthesizing efficient functional groups. For instance, DNA oligomers have been a key ligand for nanoparticle building blocks to be self-assembling via sequence-based specific organization. However, to deliver precise and scalable (programmable) assembly for a desired structure, a careful positioning of ligand molecules onto the nanoparticle counterpart should be required at the building block (precursor) level, such as direction, geometry, morphology, affinity, etc. The successful design of ligand-building block units can play an essential role in manufacturing a wide-range of new nano systems, such as nanosensor systems, nanomachines/nanobots, nanocomputers, and many more uncharted systems.
Sources: en.wikipedia.org
== Pharmacokinetics == The human oral bioavailability is approximately 50% and maximum plasma concentration was achieved within 1–2 hours after dosing. Emedastine is mainly metabolized by the liver. There are two primary metabolites: 5-hydroxyemedastine and 6-hydroxyemedastine. They are excreted in the urine as both free and conjugated forms. The 5'-oxoanalogs of 5-hydroxyemedastine, 6-hydroxyemedastine and the N-oxide are also formed as minor metabolites. The elimination half-life of oral emedastine in plasma is 3–4 hours, whereas that of topical emedastine is 10 hours. Approximately 44% of the oral dose is recovered in the urine over 24 hours with only 3.6% of the dose excreted as parent drug.
== See also == International relations since 1989 Iran–Saudi Arabia proxy conflict Iran–Israel proxy conflict Artificial intelligence arms race Arms race Nuclear arms race Digital Revolution Postmodernism Cold peace Interwar period Road to Now Ongoing armed conflicts
The other common technology used for measuring 14C activity is liquid scintillation counting, which was invented in 1950, but which had to wait until the early 1960s, when efficient methods of benzene synthesis were developed, to become competitive with gas counting; after 1970 liquid counters became the more common technology choice for newly constructed dating laboratories. The counters work by detecting flashes of light caused by the beta particles emitted by 14C as they interact with a fluorescing agent added to the benzene. Like gas counters, liquid scintillation counters require shielding and anticoincidence counters. For both the gas proportional counter and liquid scintillation counter, what is measured is the number of beta particles detected in a given time period. Since the mass of the sample is known, this can be converted to a standard measure of activity in units of either counts per minute per gram of carbon (cpm/g C), or becquerels per kg (Bq/kg C, in SI units). Each measuring device is also used to measure the activity of a blank sample – a sample prepared from carbon old enough to have no activity. This provides a value for the background radiation, which must be subtracted from the measured activity of the sample being dated to get the activity attributable solely to that sample's 14C. In addition, a sample with a standard activity is measured, to provide a baseline for comparison.
=== AI-influencers === One application of generative AI technology is the creation of virtual influencers on platforms such as OnlyFans and Instagram. These characters interact with users, mimicking real human communication and providing a fully synthetic yet convincing experience. The emergence of such influencers has raised concerns regarding consent of individuals whose voices or likenesses were used as training data, as well as the fact that AI interactions blur the line between human-created content and AI-generated material.
== See also == Battle of Czajánek's barracks British Committee for Refugees from Czechoslovakia Czechoslovak border fortifications – built 1935–1938 against Germany Fall Grün, the German invasion plan for Czechoslovakia rendered obsolete by the Munich Agreement Hodonín concentration camp International Students' Day Lety concentration camp Karel Pavlík Western betrayal
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.
No national medicines agency has approved melanotan-2 for clinical use. Afamelanotide, a related but distinct peptide, holds a marketing authorisation in the European Union for a rare photosensitivity disorder. Melanotan-2 itself is handled as a laboratory chemical.
Its broad activity across melanocortin receptors makes it a tool for probing pigmentation, appetite and vascular signalling. Early trials recorded skin darkening and other effects that were not the original focus of the work. Those observations generated hypotheses that later studies have examined.
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.