Neurotrophic factor raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-09-16. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
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.
| 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 |
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.
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.
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.
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.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
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.
=== City councilor in Porto Alegre (2001–2012) === Melo became a city councilman in Porto Alegre for the first time in 2000, after he ran for four other positions, but was not elected. He was reelected in 2004 and 2008. In 2007, he was chosen to be the president of the Municipal Chamber of Porto Alegre, which he served as from 2008 to 2009.
== History == During World War II, probenecid was used to extend limited supplies of penicillin. This use exploited probenecid's interference with drug elimination (via urinary excretion) in the kidneys and allowed lower doses of penicillin to be used. Probenecid was added to the International Olympic Committee's list of banned substances in January 1988, due to its use as a masking agent.
== Palace restoration == Princess Esra is credited with the restoration of Chowmahalla Palace and Falaknuma Palace. The former was opened to the public while the latter was leased as a luxury hotel to the Taj Group. She appointed architect Rahul Mehrotra to restore the Chowmahalla Palace. She initiated a project for the royal palaces in August 2000. The restoration project for Chowmahalla Palace involved tasks ranging from stabilising the existing structural components to reconstitution of collapsed and dilapidated sections of the complex, restoration of external and internal spaces and decorative elements and finishes.
Sources: en.wikipedia.org
A radio-frequency quadrupole (RFQ) beam cooler is a device for particle beam cooling, especially suited for ion beams. It lowers the temperature of a particle beam by reducing its energy dispersion and emittance, effectively increasing its brightness (brilliance). The prevalent mechanism for cooling in this case is buffer-gas cooling, whereby the beam loses energy from collisions with a light, neutral and inert gas (typically helium). The cooling must take place within a confining field in order to counteract the thermal diffusion that results from the ion-atom collisions. The quadrupole mass analyzer (a radio frequency quadrupole used as a mass filter) was invented by Wolfgang Paul in the late 1950s to early 60s at the University of Bonn, Germany. Paul shared the 1989 Nobel Prize in Physics for his work. Samples for mass analysis are ionized, for example by laser (matrix-assisted laser desorption/ionization) or discharge (electrospray or inductively coupled plasma) and the resulting beam is sent through the RFQ and "filtered" by scanning the operating parameters (chiefly the RF amplitude). This gives a mass spectrum, or fingerprint, of the sample. Residual gas analyzers use this principle as well.
There are several other bioprinting techniques which are less commonly used. Droplet-based bioprinting is a technique in which the bioink blend of cells and/or hydrogels are placed in droplets in precise positions. Most common amongst this approach are thermal and piezoelectric-drop-on-demand techniques. This method of bioprinting is often used experimentally with lung and ovarian cancer models. Thermal technologies use short duration signals to heat the bioink, inducing the formation of small bubbles which are ejected. Piezoelectric bioprinting has short duration current applied to a piezoelectric actuator, which induces a mechanical vibration capable of ejecting a small globule of bioink through the nozzle. A significant aspect of the study of droplet-based approaches to bioprinting is accounting for mechanical and thermal stress cells within the bioink experience near the nozzle-tip as they are extruded.
Astatine (85At) has 41 known isotopes, all of which are radioactive, whose mass numbers range from 188 to 229 except 189; they are accompanied by almost as many metastable excited states. The longest-lived isotope is 210At, which has a half-life of 8.1 hours, followed by the medically useful 211At, with a half-life of 7.214 hours. The longest-lived isomer is 202m1At with a half-life of just over 3 minutes. However, the longest-lived isotope existing in naturally occurring decay chains is 219At with a half-life of only 56 seconds.
Sources: en.wikipedia.org
^ - Indicates 2019 By- election She is the first female leader from Kerala to become the secretary of the All India Congress Committee. She is an LLB Degree holder who graduated from Kerala Law Academy in Thiruvananthapuram. She contested from Alappuzha in the 2019 Indian general election but lost to Adv. A. M. Ariff of the Communist Party of India (Marxist) by 9213 votes. In the 2019 Kerala Legislative Assembly by-elections, she won from Aroor Assembly constituency by defeating her nearest rival candidate, Manu C. Pulickal of the CPI(M) by a margin of 2,079 votes. Shanimol Osman was the only female MLA from the UDF in the 14th Kerala Legislative Assembly.
To maintain effectiveness, platelet-mimicking particles have to be engineered to remain stable in the bloodstream long enough to reach tumor sites without being rapidly cleared. Simultaneously, they must also be designed to degrade safely after successful drug delivery to tumor sites to avoid triggering adverse immune reactions. Regulatory issues and mass production also become problematic because safety and efficacy evaluation of the synthetic platelet requires extensive preclinical and clinical testing. Overcoming these deficiencies will advance their integration into standard oncological treatments.
=== Research === The molecular mechanisms of chemical toxicity, carcinogen metabolism, and inter-individual genetic variability are the main subjects of Eaton's scientific research. His early research focused on the bioactivation and detoxification pathways of Aflatoxin B1, describing species variations in Cytochrome P450 enzymes (specifically CYP1A2 and CYP3A4) and Glutathione S-transferases (GSTs) to clarify human cancer risks. Additionally, he studied glutathione production and GST-mediated detoxification of pesticides, contaminants, and medicinal substances in Phase II biotransformation. Later in his career, Eaton co-authored studies on the use of "organ-on-a-chip" microphysiological systems, such as dual liver-kidney platforms, to assess the toxicity of nanoparticles and organ damage brought on by substances like aristolochic acid.
=== Lineage-dependent features === Features of de novo genes can depend on the species or lineage being examined. This appears to partly be a result of varying GC content in genomes and that young genes bear more similarity to non-genic sequences from the genome in which they arose than do established genes. Features in the resulting protein, such as the percentage of transmembrane residues and the relative frequency of various predicted secondary structural features show a strong GC dependency in orphan genes, whereas in more ancient genes these features are only weakly influenced by GC content. The relationship between gene age and the amount of predicted intrinsic structural disorder (ISD) in the encoded proteins has been subject to considerable debate. It has been claimed that ISD is also a lineage-dependent feature, exemplified by the fact that in organisms with relatively high GC content, ranging from D. melanogaster to the parasite Leishmania major, young genes have high ISD, while in a low GC genome such as budding yeast, several studies have shown that young genes have low ISD. However, a study that excluded young genes with dubious evidence for functionality, defined in binary terms as being under selection for gene retention, found that the remaining young yeast genes have high ISD, suggesting that the yeast result may be due to contamination of the set of young genes with ORFs that do not meet this definition, and hence are more likely to have properties that reflect GC content and other non-genic features of the genome.
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.
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.