mass spectrometry 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 2026-04-21. Numbers and descriptions here follow the published literature rather than marketing material.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
| Property | Value | Notes |
|---|---|---|
| Typical purity report | 95% or higher by HPLC | Area percentage at 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray or MALDI |
| Powder storage | -20 C, desiccated | Protect from light |
| Solution storage | 2-8 C short term | Freeze aliquots for longer |
| Quality document | Certificate of analysis | States method and value |
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
=== Nutrition and dietary supplements === Reviews in 2023 and 2020 found only limited or no evidence existed to recommend any specific diet to people with FM. Studies indicate that weight management is helpful for reducing FM impact. Nutrition is related to fibromyalgia in several ways. Some nutritional risk factors for fibromyalgia complications are obesity, nutritional deficiencies, food allergies, and consuming food additives. The consumption of fruits and vegetables, low-processed foods, high-quality proteins, and healthy fats may have some benefits. Low-quality evidence found some benefits of a vegetarian or vegan diet. Although dietary supplements have been widely investigated concerning fibromyalgia, most of the evidence, as of 2021, is of poor quality. It is therefore difficult to reach conclusive recommendations. It appears that Q10 coenzyme and vitamin D supplements can reduce pain and improve quality of life for fibromyalgia patients. Q10 coenzyme has beneficial effects on fatigue in fibromyalgia patients, with most studies using doses of 300 mg per day for three months. Q10 coenzyme is hypothesized to improve mitochondrial activity and decrease inflammation. Vitamin D has been shown to improve some fibromyalgia measures, but not others.
=== Countercurrent exchange in sea and desert birds to conserve water === Sea and desert birds have been found to have a salt gland near the nostrils which concentrates brine, later to be "sneezed" out to the sea, in effect allowing these birds to drink seawater without the need to find freshwater resources. It also enables the seabirds to remove the excess salt entering the body when eating, swimming or diving in the sea for food. The kidney cannot remove these quantities and concentrations of salt. The salt secreting gland has been found in seabirds like pelicans, petrels, albatrosses, gulls, and terns. It has also been found in Namibian ostriches and other desert birds, where a buildup of salt concentration is due to dehydration and scarcity of drinking water. In seabirds the salt gland is above the beak, leading to a main canal above the beak, and water is blown from two small nostrils on the beak, to empty it. The salt gland has two countercurrent mechanisms working in it: a. A salt extraction system with a countercurrent multiplication mechanism, where salt is actively pumped from the blood 'venules' (small veins) into the gland tubules. Although the fluid in the tubules is with a higher concentration of salt than the blood, the flow is arranged in a countercurrent exchange, so that the blood with a high concentration of salt enters the system close to where the gland tubules exit and connect to the main canal.
== Lifestyle and nutrition == Regular physical activity, particularly weight-bearing and resistance exercises, has been shown to improve bone density and reduce the likelihood of fractures. While placing weight-bearing stress on these bones, it will signal the body to start strengthening and it will help stimulate bone growth to make the bones stronger over time. Adequate intake of calcium and vitamin D is essential for bone health. The National Osteoporosis Foundation recommends a daily calcium intake of 1,000 mg for men aged 50-70 and 1,200 mg for women aged 51 and older and men aged 71 and older. For vitamin D, a daily intake of 800-1,000 IU is recommended for adults aged 50 and older.
In Australia, ketamine is listed as a Schedule 8 controlled drug under the Poisons Standard (October 2015). In Canada, ketamine has been classified as a Schedule I narcotic since 2005. In December 2013, the government of India, in response to rising recreational use and the use of ketamine as a date rape drug, added it to Schedule X of the Drug and Cosmetics Act, requiring a special license for sale and maintenance of records of all sales for two years. In the United Kingdom, it was labeled a Class B drug on 12 February 2014. In 2025, the Home Office requested a review of the classification with a view to changing it to Class A, based on an increase in recreational use and the negative health consequences. The increase in recreational use prompted ketamine to be placed in Schedule III of the United States Controlled Substances Act in August 1999.
Sources: en.wikipedia.org
== Radiation-induced hair loss == Radiation induces hair loss through damage to hair follicle stem cell progenitors and alteration of keratin expression. Radiation therapy has been associated with increased mucin production in hair follicles. Studies have suggested electromagnetic radiation as a therapeutic growth stimulant in alopecia.
internal carotid the supratrochlear artery to the midline forehead. The supratrochlear artery is a branch of the ophthalmic branch of the internal carotid artery. the supraorbital artery to the lateral forehead and scalp as far up as the vertex. The supraorbital artery is a branch of the ophthalmic branch of the internal carotid artery. external carotid the superficial temporal artery gives off frontal and parietal branches to supply much of the scalp the occipital artery which runs posteriorly to supply much of the posterior aspect of the scalp the posterior auricular artery, a branch of the external carotid artery, ascends behind the auricle to supply the scalp above and behind the auricle. Because the walls of the blood vessels are firmly attached to the fibrous tissue of the superficial fascial layer, cut ends of vessels here do not readily retract; even a small scalp wound may bleed profusely. Venous drainage The veins of the scalp accompany the arteries and thus have similar names, e.g. Supratrochlear and supraorbital veins, which unite at the medial angle of the eye, and form the angular vein, which further continues as the facial vein. The superficial temporal vein descends in front of the tragus, enters the parotid gland, and then joins the maxillary vein to form the retromandibular vein. The anterior part of it unites with the facial vein to form the common facial vein, which drains into jugular vein, and ultimately to the subclavian vein. The occipital vein terminates to the sub-occipital plexus.
=== Diagnostic approach === The urate to creatinine (breakdown product of creatine phosphate in muscle) concentration ratio in urine is elevated. This is a good indicator of acid overproduction. For children under ten years of age with LNS, a urate to creatinine ratio above two is typically found. Twenty-four-hour urate excretion of more than 20 mg/kg is also typical but is not diagnostic. Hyperuricemia (serum uric acid concentration of >8 mg/dL) is often present but not reliable enough for diagnosis. Activity of the HGPRT enzyme in cells from any type of tissue (e.g., blood, cultured fibroblasts, or lymphoblasts) that is less than 1.5% of normal enzyme activity confirms the diagnosis of Lesch–Nyhan syndrome. Molecular genetic studies of the HPRT gene mutations may confirm diagnosis, and are particularly helpful for subsequent 'carrier testing' in at-risk females such as close family relatives on the female side.
Sources: en.wikipedia.org
The effects included brightened colors, increased visual contrast, open-eye visuals like colors and patterns, pareidolia, increased significance of objects, enhanced music appreciation, feeling intoxicated, self-analysis, insights, increased body awareness, feelings of joy, happiness, and peacefulness, feeling hyper and energized, feelings of empathy, things feeling ridiculous, humor and laughter, religious feelings, restlessness, social discomfort and avoidance, and nausea, among others. Mescaline was one of Shulgin's "magical half-dozen" psychedelic drugs in PiHKAL. Prominence of color with mescaline is distinctive, appearing brilliant and intense. Recurring visual patterns observed during the mescaline experience include stripes, checkerboards, angular spikes, multicolor dots, and very simple fractals that can turn very complex. The English writer Aldous Huxley described these self-transforming amorphous shapes as like animated stained glass illuminated from light coming through the eyelids in his autobiographical book The Doors of Perception (1954). Like LSD, mescaline induces distortions of form and kaleidoscopic experiences but they manifest more clearly with eyes closed and under low lighting conditions. Heinrich Klüver coined the term "cobweb figure" in the 1920s to describe one of the four form constant geometric visual hallucinations experienced in the early stage of a mescaline trip: "Colored threads running together in a revolving center, the whole similar to a cobweb". The other three are the chessboard design, tunnel, and spiral.
A burn is an injury to skin, or other tissues, caused by heat, electricity, chemicals, friction, or ionizing radiation (such as sunburn, caused by ultraviolet radiation). Most burns are thermal burns caused by contact with heat from hot fluids (called scalding), solids, or fire. Burns occur mainly in the home or the workplace. In the home, risks are associated with domestic kitchens, including stoves, flames, and hot liquids. In the workplace, risks are associated with fire and chemical and electric burns. Alcoholism and smoking are other risk factors. Burns can also occur as a result of self-harm or violence between people (assault). Burns that affect only the superficial skin layers are known as superficial or first-degree burns. They appear red without blisters, and pain typically lasts around three days. When the injury extends into some of the underlying skin layer, it is a partial-thickness or second-degree burn. Blisters are frequently present and they are often very painful. Healing can require up to eight weeks and scarring may occur. In a full-thickness or third-degree burn, the injury extends to all layers of the skin. Often there is no pain and the burnt area is stiff. Healing typically does not occur on its own. A fourth-degree burn additionally involves injury to deeper tissues, such as muscle, tendons, or bone. The burn is often black and frequently leads to loss of the burned part. Burns are generally preventable. Treatment depends on the severity of the burn.
=== Medical management === Medical management is usually reserved for horses that do not adequately respond to diet and exercise alone. The two most commonly used drugs for EMS are metformin and levothyroxine sodium. Metformin is a drug used in humans for type II diabetes, and has been shown to improve insulin sensitivity and reduce output of glucose by the liver. However, it has low bioavailability in horses, and does not appear to affect insulin sensitivity at doses that are commonly used. Its current mechanism of action in horses is thought to be a reduction in intestinal glucose absorption, and therefore postprandial glucose levels, when it is given before meals. Levothyroxine, a T4 analogue, improves insulin sensitivity and weight loss in horses. After desired body weight has been reached, horses are slowly weaned off the drug. Although it does not appear to produce signs of hyperthyroidism in horses, safety of long-term usage has not been evaluated.
=== Murder of Catherine "Rena" West === Rena maintained sporadic contact with her children on each occasion she and Fred separated. She is also known to have visited Fred's family in Much Marcle, Herefordshire, to enquire as to her children's whereabouts and welfare in the latter half of August 1971. Fred's sister-in-law, Christine, later recollected Rena was depressed and extremely anxious about her children. Being provided with Fred's Midland Road address, Rena sought to confront him—likely to discuss or demand custody of her daughters. This was the last time Rena was seen alive. She is believed to have been murdered by strangulation, possibly in the back seat of Fred's Ford Popular and likely while intoxicated. When Rena's body was discovered, a short length of metal tubing was found with her remains, leaving open a possibility she had been restrained and subjected to a sexual assault prior to her murder. The body was extensively dismembered, placed into plastic bags and buried close to a cluster of trees, known as Yewtree Coppice, at Letterbox Field.
Sources: en.wikipedia.org
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.
Dry powder is kept frozen, desiccated, and shielded from light. Dissolved material is aliquoted and frozen to limit freeze-thaw cycles. Short-term refrigerated storage is common for working solutions.
Russia registers it as a prescription nasal product. Most other markets classify it as a research chemical with no approved medical use. Oversight of purity and labeling is consequently minimal in those markets.
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.