The short version of Peptidase stability fits in a sentence. The long version — which is the one that helps — is below.
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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.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
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.
| Property | Value | Notes |
|---|---|---|
| Route studied | Intranasal | Predominant route in published reports |
| Circulation stability | Short, minutes scale | Peptidases cleave it; the tail slows the process |
| Analytical method | RP-HPLC with mass spectrometry | Used for identity and purity assessment |
| Reported outcome domains | Anxiety and cognitive measures | Derived from small, mostly regional trials |
| Regulatory status | Marketed in Russia | Availability outside that market is limited |
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.
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.
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.
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.
A wide variety of neptunium sulfide compounds have been characterized, including the pure sulfide compounds NpS, NpS3, Np2S5, Np3S5, Np2S3, and Np3S4. Of these, Np2S3, prepared by reacting NpO2 with hydrogen sulfide and carbon disulfide at around 1000 °C, is the most well-studied and three allotropic forms are known. The α form exists up to around 1230 °C, the β up to 1530 °C, and the γ form, which can also exist as Np3S4, at higher temperatures. NpS can be produced by reacting Np2S3 and neptunium metal at 1600 °C and Np3S5 can be prepared by the decomposition of Np2S3 at 500 °C or by reacting sulfur and neptunium hydride at 650 °C. Np2S5 is made by heating a mixture of Np3S5 and pure sulfur to 500 °C. All of the neptunium sulfides except for the β and γ forms of Np2S3 are isostructural with the equivalent uranium sulfide and several, including NpS, α−Np2S3, and β−Np2S3 are also isostructural with the equivalent plutonium sulfide. The oxysulfides NpOS, Np4O4S3, and Np2O2S have also been produced, although the latter two have not been well studied. NpOS was first prepared in 1985 by vacuum sealing NpO2, Np3S5, and pure sulfur in a quartz tube and heating it to 900 °C for one week. Neptunium selenide compounds that have been reported include NpSe, NpSe3, Np2Se3, Np2Se5, Np3Se4, and Np3Se5. All of these have only been obtained by heating neptunium hydride and selenium metal to various temperatures in a vacuum for an extended period of time and Np2Se3 is only known to exist in the γ allotrope at relatively high temperatures.
Iodine-131 is used for unsealed source radiotherapy in nuclear medicine to treat several conditions. It can also be detected by gamma cameras for diagnostic imaging, however it is rarely administered for diagnostic purposes only; imaging will normally be done following a therapeutic dose. Use of the 131I as iodide salt exploits the mechanism of absorption of iodine by the normal cells of the thyroid gland.
The best-characterized reference (“type”) strain of S. boulardii is CBS 5926, which is also deposited under the culture collection numbers ATCC 74012 and CNCM I-745. This strain dominates commercial use of S. boulardii and is produced by the pharmaceutical company Biocodex; it has been evaluated in more than 90 randomized clinical trials. In addition to CNCM I-745, several manufacturers market S. boulardii supplements derived from distinct, often proprietary strains, including CNCM I-1079, CNCM I-3799, and DBVPG 6763, although it remains unclear whether it is genetically identical to CBS 5926.
== Further reading == Mortison, JD; Sherman, DH (2010). "Frontiers and opportunities in chemoenzymatic synthesis". J Org Chem. 75 (21): 7041–51. doi:10.1021/jo101124n. PMC 2966535. PMID 20882949. Kim, Jinhyun; Lee, Sahng Ha; Tieves, Florian; Paul, Caroline E.; Hollmann, Frank; Park, Chan Beum (5 July 2019). "Nicotinamide adenine dinucleotide as a photocatalyst". Science Advances. 5 (7): eaax0501. doi:10.1126/sciadv.aax0501.
==== Knight Grand Cross of the Order of St Michael and St George (GCMG) ==== Diplomatic Service and Overseas List Sir (Arthur) John Coles, , Permanent Under-Secretary of State, Foreign and Commonwealth Office.
Sources: en.wikipedia.org
The expansion of Toronto in the east, in the 19th century, led to the development of housing stock along the Kingston Road and Danforth Road corridors in Scarborough. This led to the creation of a transit line. In 1893, the Toronto and Scarboro' Electric Railway, Light and Power Company built a single-track radial line along Kingston Road to Blantyre. Over the next 13 years this was extended to West Hill. In 1904, the line became the Scarboro Division of the Toronto and York Radial Railway. Service continued along this line until 1936 when it was replaced by bus service.
January 16: Establishment of a National Economic Council — any Frenchwoman over 25 may become a member. March 20: Decree amending the decree of July 28, 1906, concerning the staff of the departmental inspection of public assistance, allowing women to compete for the role of deputy inspector. 1926
== Bibliography == K.F. Warner, "Boning Lamb Cuts", Leaflet 74, U.S. Department of Agriculture, Bureau of Animal Industry, June 1931. full text. Bob Kennard, "Much ado about mutton". Ludlow: Merlin Unwin, 2014.
==== Magnesium ==== A meta-analysis has found an association between magnesium intake and depression. Magnesium was lower in serum of depressed patients than controls. A 2018 review found that Mg2+ supplementation (range 225–4000 mg) and number of weeks of treatment (range 1–12) were not related to changes in mood disorder.
In contemporary Western use, turquoise is most often encountered cut en cabochon in silver rings, bracelets, often in the Native American style, or as tumbled or roughly hewn beads in chunky necklaces. Lesser material may be carved into fetishes, such as those crafted by the Zuni. While strong sky blues remain superior in value, mottled green and yellowish material is popular with artisans.
Sources: en.wikipedia.org
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.
Intranasal delivery is the route described in most published work. It is used because the peptide is degraded quickly once it reaches circulation. Direct evidence of brain penetration in humans is lacking.
Most trials are small, regionally concentrated, and often lack rigorous blinding or placebo control. Independent replication is limited. Reviews in English generally rate the evidence as preliminary.
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.