electrospray ionization is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-01-14. Numbers and descriptions here follow the published literature rather than marketing material.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
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.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
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.
=== Resolution === The inflammatory response must be actively terminated when no longer needed to prevent unnecessary "bystander" damage to tissues. Failure to do so results in chronic inflammation, and cellular destruction. Resolution of inflammation occurs by different mechanisms in different tissues. Mechanisms that serve to terminate inflammation include:
He also contributed greatly to the identification of vitamin B complex and was co-author of more than 780 scientific papers on biochemistry and nutrition. Elvehjem commented frequently on nutrition as it affects both scientist and layman. "Vitamins should be obtained from natural foods if possible", he cautioned. "Generally they are cheaper, more palatable, and in better balance with other factors when taken in this form." He acknowledged the value of synthetic vitamins in treating deficiency diseases, but warned that their use should be temporary. Elvehjem's first graduate student (in 1931) was noted nutritionist Fredrick John Stare (1910–2002) who later founded and chaired the department of nutrition at the Harvard School of Public Health, where he served until 1976. Elvehjem met his wife Constance W. Elvehjem when she was an undergraduate at UW Madison. She died in 1999 at the age of 94 after many years supporting the museum and the Madison community. Elvehjem was stricken with a heart attack at his desk on the morning of July 27, 1962, at the age of sixty-one and died within the hour.
Somali architecture is a rich and diverse tradition of engineering and design. Spanning the country's ancient, medieval and early modern periods, it also embraces the fusion of Somalo-Islamic architecture with contemporary Western designs. In ancient Somalia, pyramidical structures known in Somali as taalo were a popular burial style, with hundreds of these dry stone monuments scattered around the country today. Houses were built of dressed stone similar to the ones in ancient Egypt. There are also examples of courtyards and large stone walls enclosing settlements, such as the Wargaade Wall. The adoption of Islam in Somalia's early medieval history brought Islamic architectural influences from Arabia and Persia. This stimulated a shift in construction from dry stone and other related materials to coral stone, sun dried bricks, and the widespread use of limestone in Somali architecture. Many of the new architectural designs, such as mosques, were built on the ruins of older structures, a practice that would continue throughout the following centuries.
=== Cooking === Chilies with a low capsaicin content can be cooked like bell peppers, for example stuffing and roasting them. Hotter varieties need to be handled with care to avoid contact with skin or eyes; washing does not efficiently remove capsaicin from skin. Chilies can be roasted over very hot coals or grilled for a short time, as they break up if overcooked. The leaves of every species of Capsicum are edible, being mildly bitter and nowhere near as hot as the fruits. They are cooked as greens in Filipino cuisine, where they are called dahon ng sili (literally "chili leaves"). They are used in the chicken soup tinola. In Korean cuisine, the leaves may be used in kimchi.
=== Cockcroft–Gault formula === A commonly used surrogate marker for the estimation of creatinine clearance is the Cockcroft–Gault (CG) formula, which in turn estimates GFR in mL/min: It is named after the scientists, the asthmologist Donald William Cockcroft (b. 1946) and the nephrologist Matthew Henry Gault (1925–2003), who first published the formula in 1976, and it employs serum creatinine measurements and a patient's weight to predict the creatinine clearance. The formula, as originally published, is:
Sources: en.wikipedia.org
Children in the Israeli–Palestinian conflict Effect of World War I on children in the United States Women in the Gaza war Humanitarian aid during the Gaza war Gaza: How to Survive a Warzone, documentary film featuring Gazan children Gaza genocide Israeli war crimes
=== Dinosaurs === It has been theorized that the neural spines of Spinosaurus, Ouranosaurus, and other dinosaurs with similar spines had humps, rather than the sailfins they are commonly depicted as having. If true, such humps would aid with heat regulation, storing of lipids for egg production, and storing fat for long migrations. Concavenator corcovatus is named for its hump (the name means "hunchback hunter from Cuenca"), but its use is debated, with theories including heat regulartion, attracting mates, intimidating rivals, or fat storage.
==== Combination drugs ==== Butalbital/acetaminophen (Butapap) – combination of butalbital (GABAA receptor positive allosteric modulator and barbiturate) and acetaminophen (analgesic) Ergotamine/caffeine (Cafergot) – combination of ergotamine (non-selective monoamine receptor modulator and ergoline) and caffeine (adenosine receptor antagonist) Ergotamine/chlorcyclizine/caffeine (Anervan) – combination of ergotamine (non-selective monoamine receptor modulator and ergoline), chlorcyclizine (antihistamine and other actions), and caffeine (adenosine receptor antagonist) Meloxicam/rizatriptan (AXS-07; Symbravo) – combination of meloxicam (COX inhibitor/NSAID) and rizatriptan (triptan) [139] Naproxen sodium/sumatriptan (MT-400; SumaRT/Nap; Suvexx; Trexima; Treximet) – combination of naproxen (COX inhibitor/NSAID) and sumatriptan (triptan) – migraine [140] Paracetamol/codeine/buclizine (Migraleve Yellow) – combination of paracetamol (analgesic) and codeine (opioid) Paracetamol/codeine/buclizine (Migraleve Pink) – combination of paracetamol (analgesic), codeine (opioid), and buclizine (antihistamine and other actions) Paracetamol/dichloralphenazone/isometheptene (Amidrine) – combination of paracetamol (analgesic), dichloralphenazone (phenazone (COX inhibitor/NSAID) and chloral hydrate (GABAA receptor positive allosteric modulator)), and isometheptene (adrenergic receptor agonist) Paracetamol/metoclopramide (Paramax) – combination of paracetamol (analgesic) and metoclopramide (various actions) Sumatriptan/naproxen (Treximet) – combination of sumatriptan (triptan) and naproxen (COX inhibitor/NSAID)
Depending on whether one chooses to have rice or a meal that is made of wheat flour such as bread or noodles as their main source of food, people within a similar culture or of a different background can make an assumption of the other's country of origin from the south or north of China. Different foods have different symbolic meanings. Mooncakes and dumplings are symbolic of the Mid-autumn festival and the Spring Festival, respectively. Pear symbolizes bad luck due to its similarity in pronunciation of 'away' in the native language and noodle means living a long life for its length. In Chinese philosophy, food frequently conveys a message. A Chinese philosophy I Ching says, "Gentlemen use eating as a way to attain happiness. They should be aware of what they say, and refrain from eating too much."
Jammu and Kashmir is home to several valleys such as the Kashmir Valley, Tawi Valley, Chenab Valley, Poonch Valley, Sind Valley, and Lidder Valley. The Kashmir Valley is 100 km (62 mi) wide and 15,520.3 km2 (5,992.4 sq mi) in area. The Himalayas divide the Kashmir Valley from the Tibetan Plateau while the Pir Panjal range, which encloses the valley from the west and the south, separates it from the Punjab Plain of the Indo-Gangetic Plain. Along the northeastern flank of the Valley runs the main range of the Himalayas. This valley has an average height of 1,850 metres (6,070 ft) above sea-level, but the surrounding Pir Panjal range has an average elevation of 10,000 feet (3,000 m). The Jhelum River is the major Himalayan river which flows through the Kashmir Valley. The southern Jammu region is mostly mountainous, with the Shivaliks, the middle and the great Himalayas running parallel to each other in a southeast–northwest direction. A narrow southwestern strip constitutes fertile plains. The Chenab, Tawi and Ravi are important rivers flowing through the Jammu region.
Sources: en.wikipedia.org
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.