nootropic 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.
Last reviewed on 2025-09-29. Where a claim depends on a specific study, the study is described rather than over-claimed.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Principal proposed target | GABA-A receptor complex | Hypothesis derived mainly from animal pharmacology |
| Common behavioral assay | Elevated plus maze | Rodent test for anxiety-like behavior |
| Reported molecular marker | Hippocampal BDNF expression | Measured by immunoassay or mRNA quantification |
| Typical dosing route | Intranasal | Chosen to reduce first-pass metabolism |
| Reported plasma half-life | Minutes | Based on limited peptide stability data |
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.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
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.
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.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
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.
=== Other === Hydrogels also possess a degree of flexibility very similar to natural tissue due to their significant water content. As responsive "smart materials", hydrogels can encapsulate chemical systems which upon stimulation by external factors such as a change of pH may cause specific compounds such as glucose to be liberated to the environment, in most cases by a gel–sol transition to the liquid state. Chemomechanical polymers are mostly also hydrogels, which upon stimulation change their volume and can serve as actuators or sensors.
Therefore, the essence of PseAAC is that on one hand it covers the AA composition, but on the other hand it contains the information beyond the AA composition and hence can better reflect the feature of a protein sequence through a discrete model. Meanwhile, various modes to formulate the PseAAC vector have also been developed, as summarized in a 2009 review article.
==== Cytotoxicity inhibition ==== One way that honokiol acts as a neuroprotective is through cellular regulation and subsequent inhibition of cytotoxicity. Two mechanisms used to achieve this inhibition are GABAA Modulation and Ca2+ Inhibition. Cytotoxicity inhibition may be the neuroprotective mechanism of honokiol. Honokiol has also been shown to inhibit repetitive firing by blocking glutamate.
== Chemistry == Protriptyline is a tricyclic compound, specifically a dibenzocycloheptadiene, and possesses three rings fused together with a side chain attached in its chemical structure. Other dibenzocycloheptadiene TCAs include amitriptyline, nortriptyline, and butriptyline. Protriptyline is a secondary amine TCA, with its N-methylated analog N–methylprotriptyline being a tertiary amine, and a structural isomer of amitriptyline. The tertiary amine analog of protriptyline, N–methylprotriptyline, has not been marketed. Other secondary amine TCAs include desipramine and nortriptyline. The chemical name of protriptyline is 3-(5H-dibenzo[a,d][7]annulen-5-yl)-N-methylpropan-1-amine and its free base form has a chemical formula of C19H21N1 with a molecular weight of 263.377 g/mol. The drug is used commercially mostly as the hydrochloride salt; the free base form is not used. The CAS Registry Number of the free base is 438-60-8 and of the hydrochloride is 1225-55-4.
Many different inventions and ideas which may or may not have been practical about auto safety have been put forward but never made it to a production car. Such items include the driver seat in the middle (to give the person a better view) (the exception being the McLaren F1 super car) and control stick steering. Automotive safety may have become an issue almost from the beginning of mechanised road vehicle development. The second steam-powered "Fardier" (artillery tractor), created by Nicolas-Joseph Cugnot in 1771, is reported by some to have crashed into a wall during its demonstration run. However, according to Georges Ageon, the earliest mention of this occurrence dates from 1801 and it does not feature in contemporary accounts. One of the earliest recorded car-related fatalities was Mary Ward, on August 31, 1869, in Parsonstown, Ireland. In 1922, the Duesenburg Model A became the first car to have four-wheel hydraulic brakes.
Sources: en.wikipedia.org
In physics, a stable isotope is a nuclide that has no detected decay on geological timescales. When discussing different elements, a stable isotope may be called a stable nuclide. The relative abundance of such stable isotopes can be measured experimentally (isotope analysis), yielding an isotope ratio that can be used as a research tool. The nuclei of stable isotopes are not radioactive and do not undergo radioactive decay. The 80 elements with one or more stable isotopes comprise a total of 251 nuclides that have not been shown to decay using current equipment. Of these 80 elements, 26 have only one stable isotope and are called monoisotopic. The other 56 have more than one stable isotope. Tin has ten stable isotopes, the largest number of any element.
The development of insulin therapy has progressed significantly since the early 20th century, starting with animal-derived insulins. In 1922, Frederick Banting and Charles Best successfully used bovine insulin extract to treat humans for the first time. This breakthrough led to the commercial production of bovine insulin in 1923 by Eli Lilly and Company. That same year, Hans Christian Hagedorn founded the Nordisk Insulinlaboratorium in Denmark, which later became Novo Nordisk. In 1926, Nordisk received a Danish charter to produce insulin as a non-profit entity. In 1936, Canadian researchers D.M. Scott and A.M. Fisher developed a zinc insulin mixture, which was licensed to Novo. During this time, Hagedorn discovered that adding protamine to insulin could prolong its action, which led to the development of Neutral Protamine Hagedorn (NPH) insulin in 1946. NPH insulin was marketed by Nordisk in 1950. By 1953, Novo also developed Lente insulin by adding zinc to porcine and bovine insulins, resulting in a longer-acting form. A significant advancement in insulin production occurred in 1978 when Genentech developed the biosynthesis of recombinant human insulin using Escherichia coli bacteria and recombinant DNA technology. This allowed for the production of insulin identical to that produced by the human pancreas. In 1981, Novo Nordisk chemically and enzymatically converted porcine insulin into human insulin. Genentech's synthetic human insulin, produced in partnership with Eli Lilly, was approved by the U.S. Food and Drug Administration in 1982.
On 9 August, Bildt compared Russia's reason for going to war with Georgia to Adolf Hitler's actions, "No state has the right to intervene militarily in the territory of another state simply because there are individuals there with a passport issued by that state or who are nationals of the state. Attempts to apply such a doctrine have plunged Europe into war in the past... And we have reason to remember how Hitler used this very doctrine little more than half a century ago to undermine and attack substantial parts of central Europe". A UN Security Council diplomat said: "Strategically, the Russians have been sending signals that they really wanted to flex their muscles, and they're upset about Kosovo." On 10 August, Russian human rights activist Sergei Kovalev called on the international community to condemn Russia's actions since Russia launched an aggression against Georgia on the pretext of defence of Russian citizens. The statement said that Russia was no longer a peacekeeper, but a party to the conflict. The statement was supported by Lev Ponomaryov and other Russian human rights activists. On 11 August, Ronald Asmus and Richard Holbrooke wrote that Georgia acted in response to provocation by Russian-backed separatists and Georgia did not want the war because it was already using soft power to attain its goals in South Ossetia.
=== Stem cell expansion === To be used for research or treatment applications, large numbers of high-quality stem cells are needed. Thus, it is necessary to develop culture systems which produce pure populations of tissue-specific stem cells in vitro without the loss of stem-cell potential. Two main approaches are taken for this purpose: two-dimensional and three-dimensional cell culture. Cell culture in two dimensions has been routinely performed in thousands of laboratories worldwide for the past four decades. In two-dimensional platforms, cells are typically exposed to a solid, rigid flat surface on the basal side and to liquid at the apical surface. Inhabiting such a two-dimensional rigid substrate requires a dramatic adaption for the surviving cells because they lack the extracellular matrix that is unique to each cell type which may alter cell metabolism and reduce its functionality. Three-dimensional cell culture systems may create a biomimicking microenvironment for stem cells, resembling their native three-dimensional extracellular matrix (ECM). Advanced biomaterials have significantly contributed to three-dimensional cell culture systems in recent decades, and more unique and complex biomaterials have been proposed for improving stem-cell proliferation and controlled differentiation. Among them, nanostructured biomaterials are of particular interest because they have the advantage of a high surface-to-volume ratio, and they mimic the physical and biological features of natural ECM at the nanoscale.
He sent Signoret specimens of American grape lice, which Signoret concluded – in 1870, while he was besieged in Paris during the Franco-Prussian War – were indeed identical to French grape lice. Meanwhile, Planchon and Lichtenstein had found vines with afflicted leaves; lice that were transferred from those leaves to the roots of healthy vines attached themselves to the vines' roots as other French grape lice did. Also in 1870, Riley discovered that American grape lice wintered on American grape vines' roots, which the insects damaged, albeit less than in the case of French vines. Riley repeated Planchon and Lichtenstein's experiment using American grape vines and American grape lice, with similar results. Thus the identity of the French and American grape lice was proven. Nevertheless, for another three years, a powerful majority in France argued that Phylloxera was not the cause of vine disease; instead, vines that were already sickly became infested with Phylloxera. Thus, in their opinion, Phylloxera was merely a consequence of the "true" disease, which remained to be found. Regardless, Riley had discovered American grape varieties that were especially resistant to Phylloxera, and by 1871, French farmers began to import them and to graft French vines onto the American rootstock. (Leo Laliman had suggested importing American vines as early as 1869, but French farmers were reluctant to abandon their traditional varieties.
Sources: en.wikipedia.org
The Ministry of Justice confirms that serial killer Levi Bellfield, who is serving two whole life sentences for murder, will be allowed to marry his girlfriend in prison as there are no legal restrictions preventing him from doing so. Boris Johnson breaks the Ministerial Code for a second time, by not asking advice from the Advisory Committee on Business Appointments before accepting a new job writing for the Daily Mail. The previous time was shortly after he stood down as foreign secretary in July 2018, when he accepted a similar job with the Daily Telegraph. A 31-year-old man is charged with three counts of murder and three of attempted murder following the Nottingham attacks. 17 June David Warburton, the MP for Somerton and Frome, becomes the fourth Conservative MP in eight days to announce their resignation from the House of Commons, doing so following his suspension from the party over allegations of sexual misconduct, and triggering a by-election in his constituency. The 2023 Trooping the Colour ceremony takes place. 18 June – Partygate: The Mirror publishes video footage of a party held in December 2020 at Conservative Party Headquarters. Housing Secretary Michael Gove describes the incident as "indefensible". 19 June – Partygate: MPs back, by 354 votes to seven, a report finding Boris Johnson deliberately misled the Commons over lockdown parties at Downing Street. 20 June The Chancellor, Jeremy Hunt, rules out direct financial support for mortgage holders, over fears it would "make inflation worse, not better".
== Explanation == The surface plasmon polariton is a non-radiative electromagnetic surface wave that propagates in a direction parallel to the negative permittivity/dielectric material interface. Since the wave is on the boundary of the conductor and the external medium (air, water or vacuum for example), these oscillations are very sensitive to any change of this boundary, such as the adsorption of molecules to the conducting surface. To describe the existence and properties of surface plasmon polaritons, one can choose from various models (quantum theory, Drude model, etc.). The simplest way to approach the problem is to treat each material as a homogeneous continuum, described by a frequency-dependent relative permittivity between the external medium and the surface. This quantity, hereafter referred to as the materials' "dielectric function", is the complex permittivity. In order for the terms that describe the electronic surface plasmon to exist, the real part of the dielectric constant of the conductor must be negative and its magnitude must be greater than that of the dielectric. This condition is met in the infrared-visible wavelength region for air/metal and water/metal interfaces (where the real dielectric constant of a metal is negative and that of air or water is positive). LSPRs (localized surface plasmon resonances) are collective electron charge oscillations in metallic nanoparticles that are excited by light. They exhibit enhanced near-field amplitude at the resonance wavelength.
Cooking with Canned Milk, including recipes and tips Archived 2017-01-29 at the Wayback Machine PET History – history of evaporated milk and the PET company. Today in Science History – John B. Meyenberg's patent describing his evaporation process of preserving milk
Degtyarenko K, Fábián P. "Directory of P450-containing Systems". International Centre for Genetic Engineering and Biotechnology (ICGEB). Archived from the original on 2016-07-16. Gao J, Ellis LB, Wackett LP. "Biocatalysis/Biodegradation Database". University of Minnesota. Archived from the original on 2012-05-30. "Substrate Product Occurrence Ratio Calculator (SPORCalc)". Archived from the original on 2009-03-18. Microbial biodegradation
=== D11AX Other dermatologicals === D11AX01 Minoxidil D11AX02 Gamolenic acid D11AX03 Calcium gluconate D11AX04 Lithium succinate D11AX05 Magnesium sulfate D11AX06 Mequinol D11AX08 Tiratricol D11AX09 Oxaceprol D11AX10 Finasteride D11AX11 Hydroquinone D11AX12 Pyrithione zinc D11AX13 Monobenzone D11AX16 Eflornithine D11AX18 Diclofenac D11AX21 Brimonidine D11AX22 Ivermectin D11AX23 Aminobenzoate potassium D11AX24 Deoxycholic acid D11AX25 Hydrogen peroxide D11AX26 Caffeine D11AX27 Oxymetazoline D11AX52 Gamolenic acid, combinations D11AX57 Collagen, combinations QD11AX90 Benzoylperoxide
Sources: en.wikipedia.org
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.
Behavioral endpoints include time spent in open arms of the elevated plus maze and avoidance latencies. Biochemical endpoints include BDNF concentration, cytokine levels, and monoamine metabolite ratios in brain tissue.
Most published studies are small, originate from a limited number of laboratories, and lack independent replication. Dose-response relationships, measured brain exposure, and long-term outcomes are not well characterized.
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.