research chemical 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.
Updated 2025-12-02. Numbers and descriptions here follow the published literature rather than marketing material.
Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
Early published reports described melanotan-2 as a tanning agent without sun protection, which means darkening is not the same as protection against ultraviolet radiation. Later studies explored the peptide in erectile dysfunction, hemorrhagic shock, and some skin conditions. No regulator in the United States or Europe has approved it for clinical use. Many products labelled melanotan-2 are sold without approval and their identity and purity are unverified. Its long-term safety in humans remains an open question.
Reversed-phase high-performance liquid chromatography is the routine method for purity assessment. Peptides absorb near 214 nm because of the peptide bond, and a gradient of acetonitrile in water separates the intact peptide from deletion sequences, oxidised products, and earlier-eluting fragments at neutral pH. Electrospray ionisation mass spectrometry provides an orthogonal check: the measured mass must agree with the theoretical value. Amino acid analysis and peptide mapping confirm structure but are used less often. Reference standards remain scarce because the peptide is not described in any pharmacopoeia.
Regulatory treatment varies by country. In the United States the peptide is not approved as a medicine, and products offered for human use may be treated as unapproved new drugs; some states also restrict sale. Australia, the United Kingdom, and European Union member states apply comparable restrictions to unapproved peptide products. Border agencies have seized shipments labelled as research chemicals. Classification may change over time, and the legal position for personal importation is not clearly settled in most published guidance.
Lyophilised melanotan-2 is supplied as a solid, which is more stable than a solution. The material is hygroscopic, so weighing is done quickly, in low humidity, with the container kept sealed. Reconstitution usually uses water for injection or bacteriostatic water, added down the wall of the vial to limit foaming. A reconstituted solution is held at 2 to 8 °C and kept away from light. Repeated freezing and thawing of the same vial is avoided because ice crystal formation and concentration effects degrade the peptide.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
Melanotan II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Retention time supports identity, while the mass spectrum confirms the molecular weight of the intact peptide. Purity is frequently reported as a percentage of total peak area, a figure that depends on the wavelength, column and gradient used. Impurity profiling may also look for truncated sequences, oxidised forms and residual counterions. Amino acid analysis and peptide mapping provide orthogonal confirmation when required.
Regulatory status varies by jurisdiction, and the substance is frequently described as unapproved for therapeutic use. Some authorities classify it alongside prescription-only medicines or controlled categories, while others address it through general consumer protection rules. Analytical surveys have reported mismatches between label claims and measured content in products sold online, although the scope of such testing is limited. Whether these discrepancies are widespread remains an open question. Discussion in the literature therefore tends to combine chemistry, supply-chain observation and policy analysis.
The epiglottis is a flap of elastic cartilage attached to the entrance of the larynx. It is covered with a mucous membrane and there are taste buds on its lingual surface which faces into the mouth. Its laryngeal surface faces into the larynx. The epiglottis functions to guard the entrance of the glottis, the opening between the vocal folds. It is normally pointed upward during breathing with its underside functioning as part of the pharynx, but during swallowing, the epiglottis folds down to a more horizontal position, with its upper side functioning as part of the pharynx. In this manner it prevents food from going into the trachea and instead directs it to the esophagus, which is behind. During swallowing, the backward motion of the tongue forces the epiglottis over the glottis' opening to prevent any food that is being swallowed from entering the larynx which leads to the lungs; the larynx is also pulled upwards to assist this process. Stimulation of the larynx by ingested matter produces a strong cough reflex in order to protect the lungs.
Economic rewards: in the case of the North American Free Trade Agreement (NAFTA), membership in the free trade agreement benefits the parties' economies. For example, Mexican companies are given better access to U.S. markets due to their membership. External actors can also contribute to economic rewards and fuel the attractiveness of IGOs – notably for developing countries. For example, external donor funding from the European Union to IGOs in the Global South. Political influence: smaller countries, such as Portugal and Belgium, who do not carry much political clout on the international stage, are given a substantial increase in influence through membership in IGOs such as the European Union. Also for countries with more influence such as France and Germany, IGOs are beneficial as the nation increases influence in the smaller countries' internal affairs and expanding other nations dependence on themselves, so to preserve allegiance. Security: membership in an IGO such as NATO gives security benefits to member countries. This provides an arena where political differences can be resolved. Democracy: it has been noted that member countries experience a greater degree of democracy and those democracies survive longer. Reasons for rejecting membership:
It also appeared in descriptions of the terrestrial agricultural practise of sub-irrigation in the late-19th century before becoming associated primarily with the cultivation of aquatic plant- and animal-species. (The Oxford English Dictionary records the common modern usage of "aquaculture" from 1887; and that of "aquiculture" from 1867.) In 1859, Stephen Ainsworth of West Bloomfield, New York, began experiments with brook trout. By 1864, Seth Green had established a commercial fish-hatching operation at Caledonia Springs, near Rochester, New York. By 1866, with the involvement of W. W. Fletcher of Concord, Massachusetts, artificial fish-hatcheries operated both in both Canada and in the United States. When the Dildo Island fish hatchery opened in Newfoundland in 1889, it was the largest and most advanced in the world. The word "aquaculture" was used in descriptions of the hatcheries experiments with cod and lobster in 1890. By the 1920s, the American Fish Culture Company of Carolina, Rhode Island, founded in the 1870s, was one of the leading producers of trout. During the 1940s, they perfected the method of manipulating the day- and night-cycle of fish so that they could be artificially spawned year-round. Californians harvested wild kelp and attempted to manage supply around 1900, later labeling it a wartime resource.
In the Peninsular War, Arthur Wellesley, 1st Duke of Wellington, renewed the Anglo-Portuguese advance into Spain just after New Year in 1812, besieging and capturing the fortified towns of Ciudad Rodrigo, Badajoz, and crushing a French army at the Battle of Salamanca. As the French regrouped, the Anglo-Portuguese entered Madrid and advanced towards Burgos, before retreating all the way to Portugal when renewed French concentrations threatened to trap them. As a consequence of the Salamanca campaign, the French were forced to end their long siege of Cádiz and to permanently evacuate the provinces of Andalusia and Asturias. In a strategic move, Wellesley planned to move his supply base from Lisbon to Santander. The Anglo-Portuguese forces swept northwards in late May and seized Burgos. On 21 June, at Vitoria, the combined Anglo-Portuguese and Spanish armies won against Joseph Bonaparte, finally breaking French power in Spain. The French had to retreat from the Iberian peninsula, over the Pyrenees. The belligerents declared an armistice from 4 June 1813 (continuing until 13 August) during which time both sides attempted to recover from the loss of approximately a quarter of a million men in the preceding two months. During this time coalition negotiations finally brought Austria out in open opposition to France. Two principal Austrian armies took the field, adding 300,000 men to the coalition armies in Germany. The Allies now had around 800,000 front-line soldiers in the German theatre, with a strategic reserve of 350,000 formed to support the front-line operations.
Sources: en.wikipedia.org
Finasteride, sold under the brand names Proscar (5 mg) and Propecia (1 mg) among others, is a medication used to treat pattern hair loss and benign prostatic hyperplasia (BPH). It can also be used to treat excessive hair growth in women. It is usually taken orally but there are topical formulations for patients with hair loss, designed to minimize systemic exposure by acting specifically on hair follicles. Along with dutasteride, finasteride is a widely dispensed 5α-reductase inhibitor. As such, it is an antiandrogen that works by decreasing the production of dihydrotestosterone (DHT) by about 70% in serum, 65-70% in scalp skin, 90% in prostate. In addition to DHT, finasteride also inhibits the production of several anticonvulsant neurosteroids including allopregnanolone, androstanediol, and tetrahydrodeoxycorticosterone. Adverse effects from finasteride are rare in men with already enlarged prostates; however, some men experience sexual dysfunction, depression, and breast enlargement. In some men, sexual dysfunction may persist after stopping the medication. It may also hide the early symptoms of certain forms of prostate cancer. Finasteride was patented in 1984 and approved for medical use in 1992. It is available as a generic medication. In 2023, it was the 91st most commonly prescribed medication in the United States, with more than 7 million prescriptions.
saline implant filled with sterile saline solution. silicone implant filled with viscous silicone gel. structured implants using nested elastomer silicone shells and two saline filled lumen. A fourth type of implant, composite (or alternative-composite) implants, have largely been discontinued. These types featured fillers such as soy oil and polypropylene string. Other discontinued materials include ox cartilage, Terylene wool, ground rubber, silastic rubber, and teflon-silicone prostheses.
protein with a deep cleft for binding the RNA substrate. The first layer is composed of three alpha helices (residues 3–13, 24-34 and 50–60) from the N-terminal half of the protein. The second layer consist of three β-hairpins (residues 61–74, 79-104 and 105-124 from the C-terminal half) arranged in two β-sheets. The hairpins 61-74 and 105-124 form a four-stranded, antiparallel β-sheet that lies on helix 3 (residues 50–60). The longest β-hairpin 79-104 mates with a short β-strand (residues 42–45) to form a three-stranded, antiparallel β-sheet that lies on helix 2 (residues 24–34). RNase A has four disulfide bonds in its native state: Cys26-Cys84, Cys58-110, Cys40-95 and Cys65-72. The first two (26-84 and 58–110) are essential for conformational folding; each joins an alpha helix of the first layer to a beta sheet of the second layer, forming a small hydrophobic core in its vicinity. The latter two disulfide bonds (40-95 and 65–72) are less essential for folding; either one can be reduced (but not both) without affecting the native structure under physiological conditions. These disulfide bonds connect loop segments and are relatively exposed to solvent. The 65-72 disulfide bond has an extraordinarily high propensity to form, significantly more than would be expected from its loop entropy, both as a peptide and in the full-length protein. This suggests that the 61-74 β-hairpin has a high propensity to fold conformationally. RNase A is a basic protein (pI = 9.63); its many positive charges are consistent with its binding to RNA (a poly-anion).
Another invasive neuromodulation treatment developed in the 1980s is deep brain stimulation, which may be used to help limit symptoms of movement disorder in Parkinson's disease, dystonia, or essential tremor. Deep brain stimulation was approved by the U.S. Food and Drug Administration in 1997 for essential tremor, in 2002 for Parkinson's disease, and received a humanitarian device exemption from the FDA in 2003 for motor symptoms of dystonia. It was approved in 2010 in Europe for the treatment of certain types of severe epilepsy. DBS also has shown promise, although still in research, for medically intractable psychiatric syndromes of depression, obsessive-compulsive disorders, intractable rage, dementia, and morbid obesity. It has also shown promise for Tourette syndrome, torticollis, and tardive dyskinesia. DBS therapy, unlike spinal cord stimulation, has a variety of central nervous system targets, depending on the target pathology. For Parkinson's disease, central nervous system targets include the subthalamic nucleus, globus pallidus interna, and the ventral intermidus nucleus of the thalamus. Dystonias are often treated by implants targeting globus pallidus interna, or less often, parts of the ventral thalamic group. The anterior thalamus is the target for epilepsy.
Chocolate agar (CHOC) or chocolate blood agar (CBA) is a nonselective, enriched growth medium used for isolation of pathogenic bacteria. It is a variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating to 80 °C. Chocolate agar is used for growing fastidious respiratory bacteria, such as Haemophilus influenzae and Neisseria meningitidis. In addition, some of these bacteria, most notably H. influenzae, need growth factors such as nicotinamide adenine dinucleotide (factor V or NAD) and hemin (factor X), which are inside red blood cells; thus, a prerequisite to growth for these bacteria is the presence of red blood cell lysates. The heat also inactivates enzymes which could otherwise degrade NAD. The agar is named for its color and contains no chocolate products.
Sources: en.wikipedia.org
=== Medication === For type B aortic dissections, patients without rupture of the aorta or organ perfusion abnormalities may be treated with medications. For others, including those with type A aortic dissections, surgery is preferred. Aortic dissection generally presents as a hypertensive emergency, and the main consideration of medical management is to decrease the shear stress in the aortic wall by decreasing blood pressure and the heart rate. The target blood pressure should be a mean arterial pressure (MAP) of 60 to 75 mmHg or a systolic blood pressure between 100-120 mmHg, or the lowest blood pressure tolerated. Initial decreases should be by about 20%. The target heart rate is 60-80 beats per minute. Long-term blood pressure control is required for every person who has experienced aortic dissection. Beta blockers are the first-line treatment for patients with acute and chronic aortic dissection. In acute dissection, fast-acting agents can be given intravenously and have doses that are easier to adjust (such as esmolol, propranolol, or labetalol) is preferred. Vasodilators such as sodium nitroprusside can be considered for people with ongoing high blood pressure, but they should never be used alone, as they often stimulate a reflexive increase in the heart rate. Opiates are commonly used for relief of severe pain and may lower the blood pressure further. Calcium channel blockers can be used in the treatment of aortic dissection, particularly if a contraindication to the use of beta-blockers exists.
== Engineering == Application of a structural load to a system Disk loading, the pressure maintained over the swept area of a helicopter's rotor Seismic loading, one of the basic concepts of earthquake engineering Wing loading, the loaded weight of an aircraft divided by the area of its wing Loading characteristic, a measure of traffic on a telephone system Insertion of an electrical load into a circuit Use of a loading coil to increase inductance Loading (computing), the process in which the contents of a file are read into a computer's memory
== See also == Politics of Serbia and Montenegro Prime Minister of Serbia and Montenegro List of heads of state of Yugoslavia President of Montenegro List of presidents of Montenegro President of Serbia List of presidents of Serbia
==== Headaches ==== Paracetamol is effective for acute migraine: 39% of people experience pain relief within one hour compared with 20% in the control group. The aspirin/paracetamol/caffeine combination also "has strong evidence of effectiveness and can be used as a first-line treatment for migraine". Paracetamol on its own only slightly alleviates episodic tension headache in those who have them frequently. However, the aspirin/paracetamol/caffeine combination is superior to both paracetamol alone and placebo and offers meaningful relief of tension headache: two hours after administering the medication, 29% of those who took the combination were pain-free as compared with 21% on paracetamol and 18% on placebo. The German, Austrian, and Swiss headache societies and the German Society of Neurology recommend this combination as a "highlighted" one for self-medication of tension headache, with paracetamol/caffeine combination being a "remedy of first choice", and paracetamol a "remedy of second choice".
Sources: en.wikipedia.org
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
Low temperature slows hydrolysis and oxidation, the two main routes by which the peptide backbone and side chains are modified. A lyophilised powder stored at −20 °C is more stable than one kept at room temperature, and once the material is dissolved the degradation rate rises, making refrigeration more important.