The short version of lyophilized fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-02-28. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Route studied | Intranasal | Predominant route in published reports |
| Circulation stability | Short, minutes scale | Peptidases cleave it; the tail slows the process |
| Analytical method | RP-HPLC with mass spectrometry | Used for identity and purity assessment |
| Reported outcome domains | Anxiety and cognitive measures | Derived from small, mostly regional trials |
| Regulatory status | Marketed in Russia | Availability outside that market is limited |
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.
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.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
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.
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.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
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.
== Structure and bonding == Thiols having the structure R−S−H, in which an alkyl group (R) is attached to a sulfhydryl group (SH), are referred to as alkanethiols or alkyl thiols. Thiols and alcohols have similar connectivity. Because sulfur atoms are larger than oxygen atoms, C−S bond lengths—typically around 180 picometres—are about 40 picometers longer than typical C−O bonds. C−S−H angles approach 90°, whereas the angle for the C−O−H group is more obtuse. In solids and liquids, the hydrogen-bonding between individual thiol groups is weak, and thus thiols are more volatile than the corresponding alcohols. The main cohesive forces for thiols involves Van der Waals interactions between the highly polarizable divalent sulfur centers. The S−H bond is much weaker than the O−H bond as reflected in their respective bond dissociation energies (BDE). For CH3S−H, the BDE is 366 kJ/mol (87 kcal/mol), while for CH3O−H, the BDE is 440 kJ/mol (110 kcal/mol). Hydrogen-atom abstraction from a thiol gives a thiyl radical with the formula RS•, where R = alkyl or aryl.
=== Medicine === Ether was once used in pharmaceutical formulations. A mixture of alcohol and ether, one part of diethyl ether and three parts of ethanol, was known as "spirit of ether", Hoffman's Anodyne or Hoffman's Drops. In the United States this concoction was removed from the Pharmacopeia at some point prior to June 1917, as a study published by William Procter, Jr. in the American Journal of Pharmacy as early as 1852 showed that there were differences in formulation to be found between commercial manufacturers, between international pharmacopoeia, and from Hoffman's original recipe. It was also used to treat hiccups through instillation into the nasal cavity.
== Notable research == From 1994 to the present the Siuzdak lab has been working on activity metabolomics. using liquid chromatography mass spectrometry-based metabolomics to identify metabolites that alter phenotype. His initial efforts with Richard Lerner, used liquid chromatography mass spectrometry to perform metabolomic experiments on the cerebral spinal fluid of sleep deprived animals. cis-9,10-octadecenoamide, a novel lipid hormone (also known as oleamide), was observed and shown to have sleep inducing properties. This work is one of the earliest such experiments combining liquid chromatography mass spectrometry and metabolomics to identify active metabolites. Another notable activity metabolomics effort with Oscar Yanes (Spain) identified neuroprotectin D1 as a metabolite that promotes stem cell differentiation. In 1996 whole virus analysis was performed with an electrospray ionization mass spectrometer where the virus was collected and successfully tested for viability. Later, he and his collaborators provided the first example of a whole intact virus (tobacco mosaic virus) being mass measured using a charge detection mass spectrometer, an instrument designed by Henry Benner and Stephen Fuerstenau at Lawrence Berkeley National Labs. In 1999, the Siuzdak lab described the use of nanostructures to enhance desorption/ionization on porous silicon of small molecules (DIOS), this is also known as the first surface-based example of surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS).
=== 21st century === In 2001, UPS acquired Mail Boxes Etc., Inc., a franchised network of packing and shipping retail centers across the United States and Canada. In 2003, the company rebranded the Mail Boxes, Etc. network as The UPS Store. In 2004, UPS entered the heavy freight business with the purchase of Menlo Worldwide Forwarding, a former subsidiary of Menlo Worldwide; UPS rebranded it as UPS Supply Chain Solutions. The purchase price was US$150 million and the assumption of US$110 million in long-term debt. On August 5, 2005, UPS announced that it had completed its acquisition of less-than-truckload (LTL) trucking company Overnite Transportation for US$1.25 billion. This was approved by the FTC and Overnite shareholders on August 4, 2005. On April 28, 2006, Overnite officially became UPS Freight. In 2005, UPS offered non-stop delivery service between Guangzhou and the United States. On October 3, 2005, UPS completed the purchase of Lynx Express, one of the largest independent parcel carriers in the United Kingdom, for £55.5 million (US$97.1 million) after receiving approval for the transaction from the European Commission. The first joint package car center operation in Dartford, Kent, was opened in 2006. On August 28, 2007, United Parcel Service celebrated its 100th anniversary. All Nippon Airways, a Star Alliance member, and UPS formed a cargo alliance and codeshare agreement to transport member cargo in 2008, similarly to an airline alliance.
That same year, the American Food and Drug Administration issued a safety alert advising medical professionals to dispose of all Lyodura that they could not confirm was from a different batch than the contaminated one, then an import alert stating that Lyodura was believed to carry Creutzfeldt–Jakob disease and shipments of it should be stopped by US customs agents as an "adulterated drug". The Australian Therapeutic Goods Administration also revoked its approval for use in 1987. The manufacturer did not keep records that allowed contaminated product to be traced back to a specific donor. According to an article published in 1991, "unsubstantiated reports suggested that donor screening was not rigidly adhered to." The cost was around $300 Canadian Dollars for a piece the size of a postage stamp. Lyodura was removed from sale in 1996. The World Health Organization recommended in 1997 that the medical field move away from cadaver-sourced dura mater grafts due to the risk of transmitting Creutzfeldt–Jakob disease highlighted by Lyodura-related cases. Dural grafts are now made from bovine tissue, various synthetic materials, or part of the patient's own body. The product's largest consumer was Japan. By 2017, 154 patients in Japan had been diagnosed with Creutzfeldt–Jakob disease after receiving dural grafts. Every patient where the brand of graft could be identified from medical records had received a Lyodura graft. Patients continued to develop symptoms up to thirty years after their surgery.
Sources: en.wikipedia.org
The communication channel is one-way, since the long antennas needed to transmit VLF or ELF waves cannot fit on a submarine. VLF transmitters use miles long wire antennas like umbrella antennas. A few nations use ELF transmitters operating around 80 Hz, which can communicate with submarines at lower depths. These use even larger antennas called ground dipoles, consisting of two ground (Earth) connections 23–60 km (14–37 miles) apart, linked by overhead transmission lines to a power plant transmitter.
==== Bailout regulator ==== The emergency breathing gas from the bailout cylinder passes through a conventional scuba first stage regulator at the cylinder valve, via a low-pressure hose, to the bailout block, where it is normally isolated by the bailout valve. When the diver needs to switch over to bailout gas they simply open the bailout valve and the gas is supplied to the helmet or mask. As the valve is normally closed, a leak in the first stage regulator seat will cause the interstage pressure to rise, and unless an overpressure relief valve is fitted to the first stage the hose may burst. Aftermarket overpressure valves are available which can be fitted into a standard low-pressure port of most first stages. If the interstage pressure for the bailout regulator is lower than the main supply pressure, the main supply will override the bailout gas, and continue to flow. This can be a problem if the diver switches to bailout because the main supply is contaminated. If, on the other hand, bailout pressure is higher than main supply pressure, the bailout gas will override the main gas supply if the valve is opened. This will result in the bailout gas being used up if the valve leaks. The diver should periodically check that bailout cylinder pressure is still sufficient for the rest of the dive, and abort the dive if it is not. For this reason the bailout regulator must be fitted with a submersible pressure gauge to which the diver can refer to check the pressure.
== Life == John H. Reynolds was born (1923-04-03)April 3, 1923 in Cambridge, Massachusetts. He studied first at Harvard University and, after serving in the Navy during World War II, at the University of Chicago. There, he was influenced by his Ph.D. thesis advisor Mark Inghram and by two other famous physicists, Harold Urey and Enrico Fermi. He specialized in mass spectrometry and utilized this method to determine isotope ratios needed for the radiometric dating of geologically and cosmologically relevant samples. In 1950 he was appointed as professor to the University of California, Berkeley where he continued his research on isotope ratios in meteorites, leading to the discovery in 1960 that the Richardton meteorite and other meteorites had an excess of xenon-129, thought to be a result of the beta decay of iodine-129 in the early Solar System. He was helped by a new all-glass spectrometer that he had designed, which allowed gas samples to be run through it multiple times, helping to increase the odds of detection and alleviate the low sensitivity problems plaguing earlier attempts by other researchers on other meteorites. Unlike many scientific discoveries, the significance of the discovery was well and widely understood at the time. His improvement of potassium-argon dating was also adopted by several institutions. Reynolds was a Guggenheim Fellow for the academic years 1956–1957 and 1986–1987. He was elected to the National Academy of Sciences in 1968. He died of pneumonia on November 4, 2000, in Berkeley, California.
March 5 Trump appoints DHS Secretary Noem as the "Special Envoy for The Shield of the Americas," a security initiative focusing on the Western Hemisphere. Trump nominates U.S. Senator Markwayne Mullin to replace Noem as DHS Secretary. The Pentagon officially designates artificial intelligence company Anthropic a supply chain risk – the first time the government has given this label to a domestic firm. Anthropic states it will challenge the decision in court. March 6 – Virginia passes legislation to prohibit schools from teaching about falsehoods of the January 6 United States Capitol attack. March 7 – Trump hosts the first Shield of the Americas summit in Doral, Florida, with 12 Latin American countries in attendance. Mach 10 – U.S. federal judge Sarah D. Morrison rules that the prediction market Kalshi constitutes as gambling and must adhere to state gambling regulations. March 11 – 2026 Minab school attack: A preliminary inquiry finds that the U.S. is at fault for an airstrike which killed 168–180 people at a girls' only elementary school in Minab, Iran. March 12 Temple Israel synagogue attack: A suspected attacker is killed after a vehicle rams into a synagogue in West Bloomfield, Michigan, and travels "with purpose down the hall of the building". 2026 Old Dominion University shooting: A former National Guardsman opens fire at an ROTC class at Old Dominion University in Norfolk, Virginia, killing the instructor and injuring two cadets. Cadets subdue the shooter, with one fatally stabbing him.
Sources: en.wikipedia.org
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.
Intranasal delivery is the route described in most published work. It is used because the peptide is degraded quickly once it reaches circulation. Direct evidence of brain penetration in humans is lacking.
Most trials are small, regionally concentrated, and often lack rigorous blinding or placebo control. Independent replication is limited. Reviews in English generally rate the evidence as preliminary.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.