This is a working overview of Intranasal route, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-10-06 and is reviewed periodically as new material appears.
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.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
| 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 |
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
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.
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.
=== Process flow disruption (PFD) === A technically simpler approach than backwashing is to set the transmembrane pressure to zero by temporarily closing off the permeate outlet, which increases the attrition of the fouling layer without the need for a second pump. PFD is not as effective as backwashing in removing fouling, but can be advantageous.
=== Amphibians === Plethodontid salamanders and chameleons have evolved a harpoon-like tongue to catch insects. The Neotropical poison dart frog and the Mantella of Madagascar have independently developed similar mechanisms for obtaining alkaloids from a diet of mites and storing the toxic chemicals in skin glands. They have also independently evolved similar bright skin colors that warn predators of their toxicity (by the opposite of crypsis, namely aposematism). Caecilians are lissamphibians that secondarily lost their limbs, superficially resembling snakes and legless lizards. Oldest known tetrapods (semi-aquatic Ichthyostegalia) resembled giant salamanders (body plan, lifestyle), though they are considered to be only distantly related.
The second most common form of SCID after X-SCID is caused by a defective enzyme, adenosine deaminase (ADA), necessary for the breakdown of purines. Lack of ADA causes accumulation of dATP. This metabolite will inhibit the activity of ribonucleotide reductase, the enzyme that reduces ribonucleotides to generate deoxyribonucleotides. The effectiveness of the immune system depends upon lymphocyte proliferation and hence dNTP synthesis. Without functional ribonucleotide reductase, lymphocyte proliferation is inhibited and the immune system is compromised.
==== Liver ==== Liver problems in people with rheumatoid arthritis may be from the underlying disease process or the medications used to treat the disease. A coexisting autoimmune liver disease, such as primary biliary cirrhosis or autoimmune hepatitis may also cause problems.
== Alternative pathway == Plants, most bacteria, and some protozoa such as malaria parasites have the ability to produce isoprenoids using an alternative pathway called the methylerythritol phosphate (MEP) or non-mevalonate pathway. The output of both the mevalonate pathway and the MEP pathway are the same, IPP and DMAPP; however, the enzymatic reactions to convert acetyl-CoA into IPP are entirely different. Interaction between the two metabolic pathways can be studied by using 13C-glucose isotopomers. In higher plants, the MEP pathway operates in plastids while the mevalonate pathway operates in the cytosol. Examples of bacteria that contain the MEP pathway include Escherichia coli and pathogens such as Mycobacterium tuberculosis.
Sources: en.wikipedia.org
=== Remaining undifferentiated === Most UCTD cases will remain undifferentiated. UCTD itself usually has a mild clinical course, particularly if there is low organ involvement. Most patients who remain undifferentiated tend not to experience major organ involvement. Up to 10–20% of patients diagnosed with UCTD will never progress to a defined disease, and their symptoms will decrease or disappear. About 12% of patients will go into remission.
=== Function === Endocannabinoids act as lipid messengers, released from one cell to activate cannabinoid receptors on nearby cells. Unlike monoamine neurotransmitters, they are lipophilic, insoluble in water, and synthesized on-demand rather than stored. They act locally due to their hydrophobic nature, unlike hormones. The endocannabinoid 2-AG is found in bovine and human maternal milk. Cannabinoids enhance sweet taste by increasing Tlc1 receptor expression and suppressing leptin, impacting energy homeostasis.
Therefore, she maintained that the cyclol model of globular proteins was still potentially viable and even proposed the cyclol fabric as a component of the cytoskeleton. However, most protein scientists ceased to believe in it and Wrinch turned her scientific attention to mathematical problems in X-ray crystallography, to which she contributed significantly. One exception was physicist Gladys Anslow, Wrinch's colleague at Smith College, who studied the ultraviolet absorption spectra of proteins and peptides in the 1940s and allowed for the possibility of cyclols in interpreting her results. As the sequence of insulin began to be determined by Frederick Sanger, Anslow published a three-dimensional cyclol model with sidechains, based on the backbone of Wrinch's 1948 "minimal cyclol" model.
== Common themes == Architect Richard Buday has contended that architectural works have been used to justify loyalty to an area's rulers, or to religious and spiritual figures. Buday suggests that "the Sphinx and the pyramids were outsized visual demands for respect and obedience to Pharaoh. The Parthenon was constructed for societal manipulation, as well as to honor a goddess (the temple's ornamentation reminded Athenians that their beating back of a Persian invasion was an act of divine intervention). Roman triumphal arches were self-aggrandizing demonstrations of rulers' might and superiority". Later in history, Buday writes that various leaders have invoked particular architectural styles to invoke connections with previous historical states and ideas which are associated with them, such as using ancient Greek and Roman imagery to convey the idea of democracy, or invoking similar classical architecture to denote imperial ambitions. In modern times, architecture is used to attract tourism.
Reporter genes are molecular tools widely used in molecular biology, genetics, and biotechnology to study gene function, expression patterns, and regulatory mechanisms. These genes encode proteins that produce easily detectable signals, such as fluorescence, luminescence, or enzymatic activity, allowing researchers to monitor cellular processes in real-time. Reporter genes are often fused to regulatory sequences of genes of interest, enabling scientists to analyze promoter activity, transcriptional regulation, and signal transduction pathways. Common reporter gene systems include green fluorescent protein (GFP), β-galactosidase (lacZ), luciferase, and chloramphenicol acetyltransferase (CAT), each offering distinct advantages depending on the experimental application. Their versatility makes reporter genes invaluable in fields such as drug discovery, gene therapy, and synthetic biology.
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.
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.