The short version of Lyophilisation fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-09-06 and is reviewed periodically as new material appears.
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.
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.
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.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
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.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Xi Jinping (born 15 June 1953) is a Chinese politician who is the paramount leader of China. He has served as the general secretary of the Chinese Communist Party (CCP) and chairman of the Party Central Military Commission (CMC) since 2012, and as the president of China and chairman of the State Central Military Commission since 2013. The elder son of Xi Zhongxun's second marriage to Qi Xin, Xi was born in Beijing. He is considered a princeling but kept a low-key image in his early career. As a teenager, his father was purged, and he was sent down to the rural village of Liangjiahe, Shaanxi, during the Cultural Revolution. He lived in a yaodong there, joined the CCP after several failed attempts, and served as the local party secretary. After studying chemical engineering at Tsinghua University as a worker-peasant-soldier student, Xi rose through the party ranks. He served as governor of Fujian from 1999 to 2002 before serving as governor and party secretary of Zhejiang from 2002 to 2007. Xi briefly replaced disgraced Shanghai party secretary Chen Liangyu in 2007, the same year he joined the Politburo Standing Committee and became the first-ranked member of the Secretariat. Appointed vice president in 2008 and vice chairman of the CMC in 2010, he succeeded Hu Jintao as China's leader in 2012, becoming the first paramount leader to be born after the foundation of the People's Republic of China. Under his leadership, China adopted the Made in China 2025 policy to promote higher-value manufacturing and reduce reliance on foreign technology.
== U.S. Environmental Protection Agency == Source: The EPA's Good Laboratory Practice Standards (GLPS) compliance monitoring program guarantees the accuracy and reliability of test data submitted to the Agency to support pesticide product registration under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), section 5 of the Toxic Substances Control Act (TSCA), and in accordance with testing consent agreements and rules issued under section 4 of TSCA. The Agency utilizes data obtained from laboratory inspections and audits to oversee the use of pesticides and industrial chemicals. 40 CFR Part 160, Good Laboratory Practice Standards pertains specifically to the Good Laboratory Practice (GLP) standards for pesticide chemicals. It establishes the requirements for conducting studies and generating data used for the registration of pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). This regulation applies primarily to studies conducted to support the registration or re-registration of pesticide products under FIFRA. It includes studies related to human health and environmental effects of pesticides. It focuses specifically on studies related to pesticide products, including toxicity studies, residue chemistry studies, environmental fate studies, and other types of studies required for pesticide registration. It operates within the context of pesticide regulation under FIFRA, which is specific to the registration and use of pesticides in the United States.
The biopolymers that comprise DNA, RNA, and (poly)peptides are linear heteropolymers (i.e.: each monomer is connected to at most two other monomers). The sequences of their monomers effectively encodes information. The transfers of information from one molecule to another are faithful, deterministic transfers, wherein one biopolymer's sequence is used as a template for the construction of another biopolymer with a sequence that is entirely dependent on the original biopolymer's sequence. When DNA is transcribed to RNA, its complement is paired to it. DNA codes are transferred to RNA codes in a complementary fashion. The encoding of proteins is done in groups of three, known as codons. The standard codon table applies for humans and mammals, but some other lifeforms (including human mitochondria) use different translations.
Sources: en.wikipedia.org
Those prejudiced against Peru were proportionally more numerous in citizens older than 53 years, and minors in those between the ages of 18 and 27, as well as in the lowest social strata, including the educational level without access to primary education provided by the Ecuadorian State. The intensity of anti-Peruvian prejudice was lower in the better informed groups, and higher in those with less information about Peru. In short, 74% of those surveyed showed aversion towards Peru. In addition, regarding the image of Peru in Ecuadorian education textbooks, these were later analyzed by Malpica and González in 1997, whose analysis evidences the psychosocial facet regarding derogatory judgments and adjectives against Peru in school textbooks, under the form of epithets that point to Peruvians as the cause of all Ecuadorian ills, and showing themselves as the "enemy to be eliminated." Concluding that a "victimization" of Ecuador is taught based on the accusation against the Peruvian state of an expansionist will against Ecuador, as well as attributing to Peruvians a series of denigrating stereotypes that foster resentment towards Peruvians and a "desire to revenge". Proof of all this was given by the President of the Ecuadorian Congress, Samuel Belletini, who came to declare on August 24, 1993, that his anti-Peruvian sentiments were the product of the education received, that he could not change them and that he ratified in them. It was also accused, by Peruvian diplomacy, that Ecuadorian politicians incited an anti-Peruvian warmongering policy to win easy votes.
== Nursing School == Affiliated to the hospital is a nursing school which graduated 295 students since 1998 up to 2001 with an average of 26 students per year to fulfill the needs of the Institute, the Ministry of health and other health organizations. In 2021, the Immunology and Therapeutic Evaluation Division at Institute was designated as a WHO Collaborating Center for Schistosomiasis Control for 3 years.
=== PET degradation === PET (Polyethylene terephthalate) belongs to the polyester family, it can be used for many purposes such as plastic bottles and filter cloth as it is thermoplastic polymer. PET can be degraded by using aminolysis which works similarly to solvolytic reaction and aminoglycolysis. For aminolysis, PET reacts with DETA (diethylenetriamine) or TETA (triethylenetetramine) which is polyamine. The reaction involves 200 - 210 Celsius. From this reaction, the products are symmetrical primary amides, asymmetrical primary/ secondary diamides, and symmetrical secondary diamides. The remaining waste material products can be used for hardening of epoxy resins. Similarly, in solvolytic reaction, the polyester reacts with water, acid, amine or alcohol, and in aminoglycolysis reaction, the polyester reacts with TEA (triethanolamine). This is PET degradation with polyamines through aminolysis route.
Sources: en.wikipedia.org
==== Slovakia ==== On 1 March 2021, Slovakia bought 2 million doses of the Sputnik V vaccine. Slovakia received the first batch of 200,000, and expected to receive another 800,000 doses in March and April. Another 1 million doses were set to arrive in May and June. On 8 April, Slovakia's drug regulator said that the Sputnik V vaccine it received did "not have the same characteristics and properties" as the version endorsed by The Lancet. The Slovak State Institute for Drug Control stated that Sputnik V has not yet been approved for use, as the first 200,000 doses received on 31 March were different from the product currently being reviewed by the European Medicines Agency as well as from the vaccine used in studies published in The Lancet. The producers have failed to reply to requests for documentation, and approximately 80% of the data was not supplied even after repeated requests. Due to the inconsistencies, it was not possible to review the safety and efficacy of the vaccine. The Russian Direct Investment Fund replied that the Slovak laboratory which tested the vaccine was not certified by the EMA. Slovak Prime Minister Igor Matovič resigned on 30 March, due to the political crisis started by the order of the Sputnik V vaccine. On 6 April 2021, the RDIF asked to return the delivered first batch of the vaccine due to "multiple contract violations". On 29 April 2021, the Slovak Ministry of Health published the Sputnik V contract.
Another data revealed that 78% of the traffickers were not subjected to capital punishment despite having brought drugs exceeding the capital threshold, as a result of plea bargains to reduce their capital charges or certifications for substantive assistance.
== Society and culture == Some commentators argue that skin cancer surgery, including Mohs surgery, is overutilised as rates of skin cancer surgery are increasing worldwide. It is unclear if this relates to higher rates of skin cancer, increased vigilance in diagnosis, and increased availability of the procedure, or patient and doctor preferences. The incidence of Mohs surgery increased significantly over the decade between 2004 and 2014. In a sample of 100 Mohs surgeries, the total cost ranged from US$474 to US$7,594, with the higher costs for hospital-based complex procedures. In Australia, the direct out of pocket cost to patients may vary from $0 to $4000. When the non-Mohs surgery is performed by multiple doctors including pathologists the costs may be increased further. This is especially true when the cancer is incompletely excised and requires repeat surgery.
In 1992, the owner of all Tim Hortons and Wendy's restaurants in Prince Edward Island, Daniel P. Murphy, decided to open new franchise outlets for both brands in the same building in the town of Montague. Murphy invited Joyce and Wendy's chairman Dave Thomas to the grand opening of the "combo store," where the two executives met for the first time. Murphy's success with combining coffee and donuts with Wendy's fast food led to the August 8, 1995, acquisition of and merger with TDL Group by Wendy's International, Inc., an American company; this lasted until 2009. The sale was widely commented on in the media. In 1995, the Toronto Star had a column reflecting on Tim Hortons "selling out" to Wendy's with "the spectacle of another great Canadian icon...gone to Yankee burgerfat".
Sources: en.wikipedia.org
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.