Everything below concerns Pro-Gly-Pro. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-03-16. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
| Property | Value | Notes |
|---|---|---|
| Dry storage temperature | -20 C or below | Sealed, desiccated, protected from light |
| Solution stability | Hours to days at 2-8 C | Depends on buffer and microbial load |
| Preferred pH range | Near neutral to slightly acidic | Alkaline pH accelerates hydrolysis |
| Main degradation routes | Hydrolysis and deamidation | No cysteine or methionine in sequence |
| Identity confirmation | Electrospray mass spectrometry | Observed mass compared with 751.9 Da |
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.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
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.
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.
== Advertising == The Guinness harp motif is modelled on the Trinity College harp. It was adopted in 1862 by the incumbent proprietor, Benjamin Lee Guinness. Harps have been a symbol of Ireland at least since the reign of Henry VIII. Guinness registered their harp as a trademark shortly after the passing of the Trade Marks Registration Act 1875. It faces right instead of left, and so can be distinguished from the Irish coat of arms. Since the 1930s, in the face of falling sales, Guinness has had prominent marketing campaigns, from television advertisements to beer mats and posters. Before then, Guinness had almost no advertising, instead allowing word of mouth to sell the product.
== Development == Episode Two was the second in a planned trilogy of shorter episodic games that would continue the story of Half-Life 2 (2004). It was developed simultaneously with Episode One (2006) by a team led by David Speyrer. This schedule of simultaneous development aided them in streamlining the story between the two games to create an immersive story. The technology used was the same for both games, allowing the development teams to quickly fix any technical problems that might arise from either game; this happened often because of the multi-platform release. The team originally planned the ending to feature a comical sequence with Lamarr, Kleiner's pet headcrab, floating in space outside the rocket Gordon launches into space; however, Valve president Gabe Newell requested killing off a major character to create a cliffhanger for Episode Three. On July 13, 2006, Valve announced that Episode Two would be released on Xbox 360 and PlayStation 3 in addition to Windows. Valve handled the development for the PC and Xbox 360, while Electronic Arts (EA) worked on the PlayStation 3 version. It was announced on September 7, 2007, that the PlayStation 3 version would be delayed because the EA studio behind the game was in the United Kingdom, away from Valve's development team, and therefore lagged behind in its schedule. According to Valve's marketing director, Doug Lombardi, the Xbox 360, PlayStation 3 and Windows versions would be identical in functionality and performance. An audio commentary is also featured, as in Episode One and Lost Coast.
== Histology == The chief cells are organized as dense cords surrounding the capillaries in the parathyroid. Parathyroid chief cells make up the majority of the parathyroid gland along with adipocytes and oxyphil cells. Parathyroid chief cells have large amounts of organelles associated with protein synthesis. As in many endocrine organs, with age, more oxyphil cells appear in the parathyroid gland. Parathyroid tissue seems to have a low turn-over rate. Chief cells appear as a dark purple in an H&E stain, with the oxyphil cells staining as a lighter pink. They are polygonal in shape with a round nucleus. Chief cells spend most time inactive due to normal calcium level conditions. These inactive cells are classified as cuboidal. They have low levels of secretory granules, as opposed to active chief cells. These granules can contain acid phosphatase. Acid phosphatase is only found in larger secretory granules, 400 to 900 nm in diameter, and is less prevalent in smaller granules. This acid phosphatase is also present in the Golgi apparatus of the chief cell. However, the Golgi apparatus areas associated with parathyroid hormone packaging contained little or no acid phosphatase. The chief cells become active in response to low calcium in the blood. The low level is sensed by the calcium- sensing receptor. These active cells have a greater electron density than the inactive chief cells. The electron density is caused by the secretory granules. The chief cell is thought to have a clear cytoplasm.
Sources: en.wikipedia.org
=== Since Silk Road === From late 2013 through to 2014, new markets started launching with regularity, such as the Silk Road 2.0, run by the former Silk Road site administrators, as well as the Agora marketplace. Such launches were not always a success; in February 2014 Utopia, the highly anticipated market based on Black Market Reloaded, opened only to shut down eight days later following rapid actions by Dutch law enforcement. February 2014 also marked the short lifespans of Black Goblin Market and CannabisRoad, two sites which closed after being deanonymized without much effort. November 2014 briefly shook the darknet market ecosystem, when Operation Onymous, executed by the United States' FBI and UK's National Crime Agency, led to the seizure of 27 hidden sites, including Silk Road 2.0, one of the largest markets at the time, as well 12 smaller markets and individual vendor sites. By September 2014, Agora was reported to be the largest market, avoiding Operation Onymous; as of April 2015, Agora has gone on to be the largest overall marketplace, with more listings than the Silk Road at its height. Further market diversification occurred in 2015, as did further developments around escrow and decentralization. In March 2015, the Evolution marketplace performed an "exit scam", stealing escrowed bitcoins worth $12 million, half of the ecosystem's listing market share at that time. The closure of Evolution led to users redistributing to Black Bank and Agora.
For interpretation, first, look for single amino acid immonium ions (H2N+=CHR2). Corresponding immonium ions for amino acids are listed in Table 1. Ignore a few peaks at the high-mass end of the spectrum. They are ions that undergo neutral molecules losses (H2O, NH3, CO2, HCOOH) from [M+H]+ ions. Find mass differences at 28 Da since b-ions can form a-ions by loss of CO. Look for b2-ions at low-mass end of the spectrum, which helps to identify yn-2-ions too. Mass of b2-ions are listed in Table 2, as well as single amino acids that have equal mass to b2-ions. The mass of b2-ion = mass of two amino acid residues + 1.
Dry ice is produced industrially through the compression and cooling of carbon dioxide. The most common industrial method of manufacturing dry ice starts with a gas having a high concentration of carbon dioxide. Such gases can be a byproduct of another process, such as producing ammonia from nitrogen and natural gas, oil refinery activities or large-scale fermentation. The carbon dioxide-rich gas is then pressurized and refrigerated until it liquefies. Next, the pressure is reduced. When this occurs some liquid carbon dioxide vaporizes, causing a rapid lowering of temperature of the remaining liquid. As a result, the extreme cold causes the liquid to solidify into a snow-like consistency. Finally, the snow-like solid carbon dioxide is compressed into small pellets or larger blocks of dry ice. Dry ice is typically produced in three standard forms: large blocks, small (1⁄2 or 5⁄8 in [13 or 16 mm] diameter) cylindrical pellets and tiny (1⁄8 inch [3.2 mm] diameter) cylindrical, high surface to volume pellets that float on oil or water and do not stick to skin because of their high radii of curvature. Tiny dry ice pellets are used primarily for dry ice blasting, quick freezing, fire fighting, oil solidifying and have been found to be safe for experimentation by middle school students wearing appropriate personal protective equipment such as gloves and safety glasses. A standard block weighing approximately 30 kg (66 lb) covered in a taped paper wrapping is most common.
The entry of U.S. troops into the war caused an intense increase in its industrial and agricultural production. However, the departure of U.S. soldiers left little labor for its economy; the remaining U.S. labor force was insufficient to meet the demands of the countryside and industry. Mexico and the United States signed an agreement in 1942 to regulate the flow of Mexican migrants (braceros) to the United States and compensate for the lack of U.S. workers. The agreement resulted in the Bracero Program. It established that braceros could not be employed in military service, could not suffer acts of discrimination, could not be used to displace U.S. workers, and that their basic needs had to be assured. The Bracero Program remained in effect until 1964 and benefited neighboring countries, securing needed labor for the United States and reducing unemployment in Mexico.
Sources: en.wikipedia.org
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.
Hydrolysis of peptide bonds and deamidation of arginine and proline residues are the main degradation routes. Alkaline pH and higher temperatures accelerate both processes. Buffered, near-neutral solutions stored cold generally degrade more slowly than unbuffered ones.
Reverse-phase chromatography gives the clearest single view of related impurities and truncated sequences. Mass spectrometry then confirms that the main peak carries the expected mass. Neither test detects enantiomeric impurities, which require a separate chiral assay.
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.