This is a working overview of intranasal delivery, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-12-17 and is reviewed periodically as new material appears.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
| Property | Value | Notes |
|---|---|---|
| Dry storage temperature | -20 C or below | Sealed, desiccated, protected from light |
| Solution stability | Hours to days at 2-8 C | Depends on buffer and microbial load |
| Preferred pH range | Near neutral to slightly acidic | Alkaline pH accelerates hydrolysis |
| Main degradation routes | Hydrolysis and deamidation | No cysteine or methionine in sequence |
| Identity confirmation | Electrospray mass spectrometry | Observed mass compared with 751.9 Da |
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
=== Nanoantennas === A graphene-based plasmonic nano-antenna (GPN) can operate efficiently at millimeter radio wavelengths. The wavelength of surface plasmon polaritons for a given frequency is several hundred times smaller than the wavelength of freely propagating electromagnetic waves of the same frequency. These speed and size differences enable efficient graphene-based antennas to be far smaller than conventional alternatives. The latter operate at frequencies 100–1000 times larger than GPNs, producing 0.01–0.001 as many photons. An electromagnetic (EM) wave directed vertically onto a graphene surface excites the graphene into oscillations that interact with those in the dielectric on which the graphene is mounted, thereby forming surface plasmon polaritons (SPP). When the antenna becomes resonant (an integral number of SPP wavelengths fit into the physical dimensions of the graphene), the SPP/EM coupling increases greatly, efficiently transferring energy between the two. A phased array antenna 100 μm in diameter could produce 300 GHz beams only a few degrees in diameter, instead of the 180 degree radiation from a conventional metal antenna of that size. Potential uses include smart dust, low-power terabit wireless networks and photonics. A nanoscale gold rod antenna captured and transformed EM energy into graphene plasmons, analogous to a radio antenna converting radio waves into electromagnetic waves in a metal cable. The plasmon wave fronts can be directly controlled by adjusting antenna geometry.
In the summer of 1969, weary from these activities, Adorno returned once again to Zermatt, Switzerland, at the foot of Matterhorn to restore his strength. On 6 August, during a vacation in Visp, he died of a heart attack.
==== Valvular heart disease ==== Diseased heart valves that have become abnormally narrow or abnormally leaky may require surgery. This is traditionally performed as an open surgical procedure to replace the damaged heart valve with a tissue or metallic prosthetic valve. In some circumstances, the tricuspid or mitral valves can be repaired surgically, avoiding the need for a valve replacement. Heart valves can also be treated percutaneously, using techniques that share many similarities with percutaneous coronary intervention. Transcatheter aortic valve replacement is increasingly used for patients considered to be at very high risk for open valve replacement.
=== Gene cluster === Tolypocladium inflatum, the species currently used for mass production of Cyclosporin, has the biosynthetic genes arranged into a 12-gene cluster. Of these 12 genes, SimA (Q09164) is the cyclosporin synthetase, SimB (CAA02484.1) is the alanine racemase, and SimG (similar to ATQ39432.1) is the polyketide synthase. These genes are associated with an active retrotransposon. Although these sequences are poorly-annotated on GenBank and other databases, 90% similar sequences can be found for the Cyclosporin-producing Beauveria felina (or Amphichorda ~). SimB has two paralogs in the same organism with different but overlapping functions thanks to their low specificity.
Sources: en.wikipedia.org
=== Detection in body fluids === Pseudoephedrine may be quantified in blood, plasma, or urine to monitor any possible performance-enhancing use by athletes, confirm a diagnosis of poisoning, or to assist in a medicolegal death investigation. Some commercial immunoassay screening tests directed at the amphetamines cross-react appreciably with pseudoephedrine, but chromatographic techniques can easily distinguish pseudoephedrine from other phenethylamine derivatives. Blood or plasma pseudoephedrine concentrations are typically in the 50 to 300 μg/L range in persons taking the drug therapeutically, 500 to 3,000 μg/L in people with substance use disorder involving pseudoephedrine or poisoned patients, and 10 to 70 mg/L in cases of acute fatal overdose.
Layer 1 Layer 1 is the shallowest layer and includes the deepest, ventilated layer in winter; it has received tritium via radioactive fallout and lost some due to advection and/or vertical diffusion and contains about 28% of the total amount of tritium. Layer 2 Layer 2 is below the first layer but above the 26.81 isopycnal and is no longer part of the mixed layer. Its two sources are diffusion downward from the mixed layer and lateral expansions outcropping strata (poleward); it contains about 58% of the total tritium. Layer 3 Layer 3 is representative of waters that are deeper than the outcrop isopycnal and can only receive tritium via vertical diffusion; it contains the remaining 14% of the total tritium.
ATAC-seq (Assay for Transposase-Accessible Chromatin using sequencing) is a laboratory technique used in molecular biology to assess genome-wide chromatin accessibility. The technique was introduced in 2013 by the labs of Will Greenleaf and Howard Chang at Stanford University as an alternative to MNase-seq, FAIRE-Seq and DNase-Seq with faster turnaround time, simpler protocol, and lower DNA input requirements.
In 1976, Guillaume played Nathan Detroit in the Broadway revival of Guys and Dolls and was nominated for a Tony Award. In 1990, Guillaume was cast in the Los Angeles production of The Phantom of the Opera, replacing Michael Crawford in the title role. Guillaume was the first Black actor to portray the character.
The International Cryosphere Climate Initiative (ICCI) publishes its annual State of the Cryosphere Report. It warns of rapid, irreversible sea-level rise from Earth's ice sheets, which could potentially reach 12–20 metres in the coming centuries. 17 November – The global average temperature temporarily exceeds 2 °C above the pre-industrial average for the first time in recorded history. 20 November – A study of censorship in science finds it to be often driven by scientists themselves, motivated by prosocial concerns or reputation protection. 22 November – An autonomous excavator is demonstrated. Using sensors, the machine can generate 3D maps of a construction site, localising individual blocks and stones in order to build a wall. 23 November Astrophysicists report the detection of "Amaterasu", the second highest-energy cosmic ray ever known, second only to the Oh-My-God particle of 1991. Amaterasu originated from the Local Void and its energy exceeded 240 exa-electron volts (EeV). Researchers report the deep learning-based discovery of nearly 200 functionally diverse natural machineries for CRISPR gene editing. 26 November – Astronomers report evidence, for the first time, of an overmassive black hole galaxy (O.B.G.), the result of "heavy black hole seed formation from direct collapse", an alternative way of producing a black hole other than the collapse of a dead star. This discovery was found in studies of UHZ1, a very early galaxy containing a quasar, by the Chandra X-ray Observatory and James Webb Space Telescope.
Sources: en.wikipedia.org
==== Reactions of tyrosines ==== Tyrosine residues are relatively unreactive; therefore they have not been a popular targets for bioconjugation. Recent development has shown that the tyrosine can be modified through electrophilic aromatic substitutions (EAS) reactions, and it is selective for the aromatic carbon adjacent to the phenolic hydroxyl group. This becomes particularly useful in the case that cysteine residues cannot be targeted. Specifically, diazonium effectively couples with tyrosine residues (diazonium salt shown as reagent in the first reaction in Figure 3 below), and an electron withdrawing substituent in the 4-position of diazonium salt can effectively increase the efficiency of the reaction. Cyclic diazodicarboxyamide derivative like 4-Phenyl-1,2,4-triazole-3,5-dione (PTAD) were reported for selective bioconjugation on tyrosine residues (the second reaction in Figure 3 below). A three-component Mannich-type reaction with aldehydes and anilines (the last reaction in Figure 3) was also described to be relatively tyrosine-selective under mild optimised reaction conditions.
=== Prescreening === A significant number of countries maintain prescreening facilities for passengers departing from other jurisdictions to clear border controls before arrival, thereby skipping checkpoints upon arrival. Aside from simplifying arrival formalities, this enables border control authorities to deny entry to potentially inadmissible travellers before they embark and to reduce congestion at border checkpoints at ports of arrival.
Hong Kong is a special administrative region of China, with executive, legislative, and judicial powers devolved from the national government. The Sino-British Joint Declaration provided for economic and administrative continuity through the handover, resulting in an executive-led governing system largely inherited from the territory's history as a British colony. Under these terms and the "one country, two systems" principle, the Basic Law of Hong Kong is the regional constitution. The regional government is composed of three branches:
=== Red blood cell transfusions === Blood transfusions are the main treatment approach for prolonging life. Donated healthy red blood cells have a functional life of 4 to 6 weeks before they wear out and are broken down in the spleen. Regular transfusions every three to four weeks are necessary in order to maintain hemoglobin at a healthy level. Transfusions come with risks including iron overload, the risk of acquiring infections, and the risk of immune reaction to the donated cells (alloimmunization).
=== 1994–1999: The Double Trio, Vrooom, Thrak and the ProjeKcts === In the summer of 1991, Belew met with Fripp in England to express an interest in reviving King Crimson. That year saw the release of the retrospective box set Frame by Frame: The Essential King Crimson. A follow-up box set, The Great Deceiver, appeared the following year as the first release on Fripp's newly-established record label Discipline Global Mobile (DGM), formed with producer David Singleton. Subsequently, DGM would be the primary home for Fripp's work, with larger album releases distributed to bigger record companies (initially Virgin Records), and smaller releases handled by DGM. This afforded Fripp and his associates greater creative freedom and more control over all aspects of their work.
Sources: en.wikipedia.org
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.
Hydrolysis of peptide bonds and deamidation of arginine and proline residues are the main degradation routes. Alkaline pH and higher temperatures accelerate both processes. Buffered, near-neutral solutions stored cold generally degrade more slowly than unbuffered ones.
Reverse-phase chromatography gives the clearest single view of related impurities and truncated sequences. Mass spectrometry then confirms that the main peak carries the expected mass. Neither test detects enantiomeric impurities, which require a separate chiral assay.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.