This is a working overview of freeze-thaw cycle, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-03-11. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
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.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
=== Unemployment === In 2007, women represented 45% of the active workforce (approximately 11.2 million) and had an unemployment rate of 9.1%, compared to 7.8% for men. By 2012, unemployment rose to 10% for women and 9.7% for men. Since 2014, the male unemployment rate has exceeded that of women, according to INSEE data.
Also, recession that is left untreated can be maintained and the inflammation kept at bay with proper brushing and oral hygiene technique. On the other hand, if one desires to pursue corrective therapy, there are a wide variety of techniques ranging from autograft (one's own tissue, usually taken from the palate), allograft (another's tissue, cadaver tissue), xenograft (animal tissue, usually porcine or bovine) or simply repositioning of the tissue native to the site.
The live album Radical Action to Unseat the Hold of Monkey Mind, was released in September 2016, drawing from 2015 concert dates of Japan, Canada and France featuring Rieflin. A 4-disc set aimed at documenting the band's ever-evolving live setlist, it included one performance of every song the band presented onstage during the tour and concert footage mostly recorded in Takamatsu, Japan, on 19 December 2015. On 7 December 2016, founding King Crimson member Greg Lake died of cancer. Another former King Crimson member, John Wetton, died of colon cancer on 31 January 2017. On 3 January 2017, Rieflin returned to King Crimson. Since the band also wished to retain Stacey, King Crimson became an octet, which Fripp initially referred to as the "Double Quartet Formation". Rieflin later eschewed drumming with the group and became King Crimson's first full-time keyboardist, with Fripp rechristening the line-up the "Three Over Five" (or "Five Over Three") formation. On 2 June 2017, King Crimson released a new live EP named Heroes, featuring a cover of the David Bowie song of the same name. The EP was intended as a tribute to Bowie, for whom Fripp had provided distinctive guitar work on the albums "Heroes" (1977) and Scary Monsters (and Super Creeps) (1980). The video for King Crimson's version of "Heroes" won "Video of the Year" at the 2017 Progressive Music Awards. Shortly afterwards, King Crimson embarked on the first leg of a North American tour, from 11 June until 19 July.
==== Human biofluid metabolomes ==== Scientists at the University of Alberta have been systematically characterizing specific biofluid metabolomes including the serum metabolome, the urine metabolome, the cerebrospinal fluid (CSF) metabolome and the saliva metabolome. These efforts have involved both experimental metabolomic analysis (involving NMR, GC-MS, ICP-MS, LC-MS and HPLC assays) as well as extensive literature mining. According to their data, the human serum metabolome contains at least 4,200 different compounds (including many lipids), the human urine metabolome contains at least 3,000 different compounds (including hundreds of volatiles and gut microbial metabolites), the human CSF metabolome contains nearly 500 different compounds while the human saliva metabolome contains approximately 400 different metabolites, including many bacterial products.
== Diagnosis == The diagnosis is made clinically, and usually this is clear cut if the lesion is associated with the flange of a complete denture. Tissue biopsy is not usually indicated before removal of the lesion, since the excises surgical specimen is usually sent for histopathologic examination and the diagnosis is confirmed retrospectively. Rarely, incisional biopsy may be indicated to rule out neoplasia, e.g. in the presence of suspicious ulceration. The appearance may also be confused with pyogenic granuloma. The excessive tissue is composed of cellular, inflamed fibrous connective tissue. The appearance of an epulis fissuratum microscopically is an overgrowth of cells from the fibrous connective tissue. The epithelial cells are usually hyperkeratotic and irregular, hyperplastic rete ridges are often seen.
Sources: en.wikipedia.org
Peptide signaling plays a significant role in various aspects of plant growth and development and specific receptors for various peptides have been identified as being membrane-localized receptor kinases, the largest family of receptor-like molecules in plants. Signaling peptides include members of the following protein families.
== How to determine GBeta == The index is derived from a mathematical model of insulin-glucose homeostasis that incorporates fundamental physiological motifs. For diagnostic purposes, it is calculated from fasting insulin and glucose concentrations with:
A juice bar is an establishment that primarily serves prepared juice beverages such as freshly squeezed or extracted fruit juices, juice blends, fruit smoothies (a thick fruit drink, often iced), or other juices such as fresh wheatgrass juice. Sometimes other solid ingredients or nutritional supplements may be added as boosters, such as fresh bananas, nuts or nut butter, bodybuilding supplements, soy protein powder, or others such as whey or hemp protein powders, wheat germ, spirulina, or chlorella. Also, if less juice is used with these same ingredients, drinks called health shakes may be produced. Juice bars share some of the characteristics of a coffeehouse, a soda fountain, a café, and a snack bar, such as providing blended drinks and food, such as sandwiches. Juice bars may be standalone businesses in cities or located at gyms, along commuter areas, near lunchtime areas, at beaches, or at tourist attractions. In Mexico, juice bars have become more popular in the 2000s. Mexican juice bars often also sell healthy beverages and snacks.
== Biosynthesis == The biosynthesis of streptogramin B is carried out by large multifunctional enzymes called non-ribosomal peptide synthetases (NRPS). In the NRPS system, each amino acid is activated as an aminoacyladenylate and is linked to the enzyme as a thioester with a phosphopantetheinyl group. An elongation reaction then occurs by transferring the activated carboxyl to the amino group in the next amino acid, thus executing the N-to-C stepwise condensation. NRPSs contain several modules on a single polypeptide. Each of these modules can catalyze activation, condensation and a modification reaction specific to one kind of amino acid. A typical elongation module consists of an adenylation domain (A), a peptidyl carrier protein domain (PCP) and a condensation domain (C). Some other domains may be present that are responsible for modifications to the residues, such as epimerization domain (E) and N-methyltransferase domain (MT). The domain responsible for the termination is the thioesterase domain (TE) located in the final module.
The 2025 Cleveland Guardians season was the 125th season for the franchise, which competes in the American League of Major League Baseball (MLB). On July 6, they were 15.5 games back of the first place Detroit Tigers and were as many as 11 games back on September 4. However, the Guardians surged while the Tigers collapsed and took the American League Central lead on September 23 with a win over the Tigers. With the Guardians having trailed Detroit by 15.5 games in July, this ranked as the largest divisional comeback in MLB history. In addition to the historic division comeback, the Guardians also became the fifth team to make the playoffs while being sub-.500 on September 4 or later. On September 27, with a walk-off win over the Texas Rangers, the Guardians clinched a postseason berth, taking the sixth and final postseason spot in the American League. On September 28, with the Tigers' loss to the Red Sox, the Guardians clinched the American League Central division for the second consecutive time and the sixth time in ten years (2016–2018, 2022, 2024–2025). However, they lost to the Tigers in the Wild Card Series.
Sources: en.wikipedia.org
== External links == GeneReviews/NCBI/NIH/UW entry on Cystinosis Human CTNS genome location and CTNS gene details page in the UCSC Genome Browser. Genetics Home Reference page on CTNS. Genetic Testing Registry.
=== Pharmacodynamics === Pinoline shows affinity for serotonin receptors, including the serotonin 5-HT1A, 5-HT2A, 5-HT2B, 5-HT2C, and 5-HT7 receptors (Ki = 156–4,335 nM). It is a high-efficacy partial agonist of the serotonin 5-HT2A receptor, an antagonist of the serotonin 5-HT2B receptor, and a full agonist of the serotonin 5-HT2C receptor, with EC50Tooltip half-maximal effective concentration (EmaxTooltip maximal efficacy) values of 2,140 nM (75%) at the serotonin 5-HT2A receptor and 33 nM (95%) at the serotonin 5-HT2C receptor and an IC50Tooltip half-maximal inhibitory concentration of 1,120 nM at the serotonin 5-HT2B receptor. Hence, pinoline appears to act as a potent and selective serotonin 5-HT2C receptor agonist. The drug shows affinity for the serotonin transporter (SERT) (Ki = 172–572 nM). It is a serotonin reuptake inhibitor, with an IC50 value of 1,100 nM. Pinoline shows affinity for the imidazoline I2 receptor (Ki = 1,640 nM) and for the α2-adrenergic receptor (Ki = 7,830 nM). Conversely, it shows no affinity for the dopamine D2 receptor (Ki = >10,000 nM). The drug is a weak monoamine oxidase inhibitor (MAOI), with an IC50 value for inhibition of MAO-ATooltip monoamine oxidase A of 41,500 nM. Both pinoline and tryptoline partially substitute for the psychedelic drug LSD in rodent drug discrimination tests. The substitution by tryptoline was further assessed and was found to be blocked by the serotonin receptor antagonist pizotifen and by the serotonin synthesis inhibitor para-chlorophenylalanine (PCPA).
=== Statistics === In 2022, the sector with the highest number of companies registered in Denmark is Finance, Insurance, and Real Estate with 204,853 companies followed by Services and Retail Trade with 204,050 and 30,563 companies respectively.
=== Dual-mode === In dual-mode, the mobile and stationary phases are reversed part way through the separation experiment. This requires changing the phase being pumped through the column as well as the direction of flow. Dual-mode operation is likely to elute the entire sample from the column but the order of elution is disrupted by switching the phase and direction of flow.
Acetolactate synthase Acetohydroxy acid isomeroreductase Dihydroxyacid dehydratase α-Isopropylmalate synthase α-Isopropylmalate isomerase Leucine aminotransferase Synthesis of the small, hydrophobic amino acid valine also includes the initial part of this pathway.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
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.