Pro-Gly-Pro comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-09-09. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
| Property | Value | Notes |
|---|---|---|
| Common route | Intranasal | Also injected in some animal work |
| Solubility class | Freely soluble in water | Solid form is hygroscopic |
| Typical storage | About -20 degrees Celsius | Keep desiccated and dark |
| Purity method | Reverse-phase HPLC | Reported as area percent |
| Confirmatory method | Mass spectrometry | Verifies expected molecular mass |
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.
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.
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.
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.
The United States' efforts to assert influence over the region, particularly regarding the construction and control of the Panama Canal, contributed to the secession of the Department of Panama in 1903 and its political independence. The United States paid Colombia $25,000,000 in 1921, seven years after completion of the canal, as redress for President Theodore Roosevelt's role in the creation of Panama, and Colombia recognized Panama under the terms of the Thomson–Urrutia Treaty. Colombia and Peru went to war because of territory disputes far in the Amazon basin. The war ended with a peace deal brokered by the League of Nations. The League finally awarded the disputed area to Colombia in June 1934.
== Contraindications == People with chronic kidney disease and large total body surface area (TBSA) burns should not use nitrofurazone, as topical preparations commonly contain polyethylene glycol, which is readily absorbed through the skin. Rapid absorption of the medication induces increased serum osmolalities and anion gap, leading to death. Symptoms are similar to ethylene glycol poisoning, in that increased serum calcium levels occur concurrently with decreased ionized calcium. Nitrofurans have been found in honey, meat and seafood. In people who have glucose-6-phosphate dehydrogenase deficiency (G-6-PD deficiency), ingestion of fish, poultry, or other foodstuff that has been treated with nitrofurans, will likely suffer from hemolysis of red blood cells as a result of eating the contaminated food.
In this section, the principal GUT models and their variants are briefly introduced, focusing on their proton decay predictions. For a comprehensive overview of Grand Unified Theories, see the dedicated article. SU(5): introduced in 1974 by Georgi and Glashow, is the minimal choice for unification in a simple group. One SM generation of particles comes from
The liver is the second largest organ (after the skin) and is an accessory digestive gland which plays a role in the body's metabolism. The liver has many functions some of which are important to digestion. The liver can detoxify various metabolites; synthesise proteins and produce biochemicals needed for digestion. It regulates the storage of glycogen which it can form from glucose (glycogenesis). The liver can also synthesise glucose from certain amino acids. Its digestive functions are largely involved with the breaking down of carbohydrates. It also maintains protein metabolism in its synthesis and degradation. In lipid metabolism it synthesises cholesterol. Fats are also produced in the process of lipogenesis. The liver synthesises the bulk of lipoproteins. The liver is located in the upper right quadrant of the abdomen and below the diaphragm to which it is attached at one part, the bare area of the liver. This is to the right of the stomach and it overlies the gall bladder. The liver synthesises bile acids and lecithin to promote the digestion of fat.
On 12 June 1944 U.S. carriers made air strikes on the Marianas, convincing Admiral Soemu Toyoda that the U.S. was preparing to invade. This move came as a surprise; the Japanese had expected the next U.S. target to be further south, either at the Carolines or the Palaus, and had protected the Marianas with only 50 land-based aircraft. On 13–15 June, American carriers made additional airstrikes while surface forces bombarded the Marianas. On 15 June, the first American troops went ashore on Saipan. Since control of the Marianas would bring American strategic bombers within range of the Japanese home islands, the IJN decided it was time for the long-awaited Kantai Kessen (decisive battle). Toyoda immediately ordered a fleet-based counterattack, committing nearly all of the Japanese navy's serviceable ships. The main portions of the fleet rendezvoused on 16 June in the western part of the Philippine Sea and completed refueling on 17 June. Admiral Jisaburō Ozawa commanded this force from his newly commissioned flagship, Taihō. In addition to extensive command facilities, reinforced torpedo blisters and a large air group, Taihō was the first Japanese carrier with an armor-plated flight deck, designed to withstand bomb hits with minimal damage. At 18:35 on 15 June the submarine USS Flying Fish sighted a Japanese carrier and battleship force coming out of the San Bernardino Strait. An hour later USS Seahorse spotted a battleship and cruiser force steaming up from the south, 200 miles (320 km) east of Mindanao.
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The reef is seeded with young abalone from an onshore hatchery. The abalone feed on seaweed that has grown naturally on the habitats, with the ecosystem enrichment of the bay also resulting in growing numbers of dhufish, pink snapper, wrasse, and Samson fish, among other species. Brad Adams, from the company, has emphasised the similarity to wild abalone and the difference from shore-based aquaculture. "We're not aquaculture, we're ranching, because once they're in the water they look after themselves."
in the gray short-tailed opossum (Monodelphis domestica), a marsupial, MHC spans 3.95 Mb, yielding 114 genes, 87 shared with humans. Marsupial MHC genotypic variation lies between eutherian mammals and birds, taken as the minimal MHC encoding, but is closer in organization to that of nonmammals. The IPD-MHC Database was created which provides a centralised repository for sequences of the Major Histocompatibility Complex (MHC) from a number of different species. As of the release on December 19, 2019, the database contains information on 77 species.
=== General === In Christian iconography, some works of art depict women with their breasts in their hands or on a platter, signifying that they died as a martyr by having their breasts severed; one example of this is Saint Agatha of Sicily.
The average stretched penile length at birth is about 4 cm (1.6 in), and the length for 90% of newborn boys is between 2.4 and 5.5 cm (0.94 and 2.17 in). Limited growth of the penis occurs between birth and 5 years of age, but very little occurs between 5 years and the onset of puberty. The average size at the beginning of puberty is 6 cm (2.4 in), with adult size reached about 5 years later. W. A. Schonfeld published a penis growth curve in 1943.
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The meridians (经络, jīng-luò) are believed to be channels running from the zàng-fǔ in the interior (里, lǐ) of the body to the limbs and joints ("the surface" [表, biaǒ]), transporting qi and xuĕ. TCM identifies 12 "regular" and 8 "extraordinary" meridians; the Chinese terms being 十二经脉 (shí-èr jīngmài, lit. "the Twelve Vessels") and 奇经八脉 (qí jīng bā mài) respectively. There's also a number of less customary channels branching from the "regular" meridians.
=== Legal categorization and legal issues in a near future === Currently, siRNAs are chemically synthesized and are therefore legally categorized in the EU and the US as simple medicinal products. But as bioengineered siRNA (BERAs) are in development, these would be classified as biological medicinal products, at least in the EU. The development of the BERAs technology raises the question of the categorization of drugs having the same mechanism of action but being produced chemically or biologically. This lack of consistency should be addressed.
David Crocker, a member of the ARPANET research community, writing in the Post, said, "The reports incorrectly credited [EMAIL's] author, a 14-year-old in the late 1970s, as the 'inventor' of email, long after it had become an established service on the ARPANET." Another computer historian, Marc Weber, a curator at the Computer History Museum, said that by 1978, "nearly all the features we're familiar with today had appeared on one system or another over the previous dozen years", including emoticons, mailing lists, and spam mail. After the controversy unfolded, MIT disassociated itself from Ayyadurai's EMAIL Lab and funding was dropped. MIT also revoked Ayyadurai's contract to lecture at the bioengineering department. Ayyadurai characterized the earlier work of Tomlinson, Tom Van Vleck and others as text messaging, rather than an electronic version of an interoffice mail system.
=== Legal definition === As of 23 November 2009, the Scotch Whisky Regulations 2009 (SWR) define and regulate the production, labelling, packaging as well as advertising of Scotch whisky in the United Kingdom. They replace previous regulations that focused solely on production, including the Scotch Whisky Act 1988. Since the previous act focused primarily on production standards, it was repealed and superseded by the 2009 Regulations. The SWR includes broader definitions and requirements for the crafting, bottling, labelling, branding, and selling of "Scotch Whisky". International trade agreements have the effect of making some provisions of the SWR apply in various other countries as well as in the UK. The SWR defines "Scotch whisky" as whisky that:
== Mechanism of action == Didanosine (ddI) is a nucleoside analogue of adenosine. It differs from other nucleoside analogues, because it does not have any of the regular bases, instead it has hypoxanthine attached to the sugar ring. Within the cell, ddI is phosphorylated to the active metabolite of dideoxyadenosine triphosphate, ddATP, by cellular enzymes. Like other anti-HIV nucleoside analogs, it acts as a chain terminator by incorporation and inhibits viral reverse transcriptase by competing with natural dATP.
Sources: en.wikipedia.org
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.
Reported human trials are few, brief and originate mainly from one country. They describe effects on anxiety-related measures, but sample sizes are small and reporting is limited. The results are widely regarded as preliminary rather than confirmed.
Reverse-phase liquid chromatography is used to assess purity and separation of related impurities. Mass spectrometry confirms that the observed molecular mass matches the expected peptide. A certificate of analysis from the supplier is the usual document of record.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.