Heptapeptide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-07-30. Anything still debated is marked as such rather than presented as settled.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Primary route studied | Intranasal | Also examined parenterally in animal work |
| Reported plasma half-life | Minutes to tens of minutes | Values vary widely between reports |
| Main model systems | Rodent behavioural and cell assays | Human trials are few and small |
| Principal proposed targets | GABA-A receptor, GABA transaminase | Monoamine and neurotrophic pathways also reported |
| Evidence grade | Preliminary | Limited independent replication |
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.
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.
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.
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.
Biological value (BV) is a measure of the proportion of absorbed protein from a food which becomes incorporated into the proteins of the organism's body. It captures how readily the digested protein can be used in protein synthesis in the cells of the organism. Proteins are the major source of nitrogen in food. BV assumes protein is the only source of nitrogen and measures the amount of nitrogen ingested in relation to the amount which is subsequently excreted. The remainder must have been incorporated into the proteins of the organisms body. A ratio of nitrogen incorporated into the body over nitrogen absorbed gives a measure of protein "usability" – the BV. Unlike some measures of protein usability, biological value does not take into account how readily the protein can be digested and absorbed (largely by the small intestine). This is reflected in the experimental methods used to determine BV. BV uses two similar scales:
=== 1944 coup d'état === At the end of August, the parliament considered various options for forming a new government, including a Fatherland Front cabinet led by Kimon Georgiev. On 27 August he was sent with police guards to the regents in Chamkoria and they tried to persuade him to join a cabinet without the Communists, but Georgiev refused, after which he was released and returned to Sofia. On 30 August, he was among the 14 leaders of the Fatherland Front who issued a Manifesto to the Bulgarian People, the organization's first public document signed by specific individuals. In the following days, Kimon Georgiev's house became the centre of the coup prepared by the Fatherland Front, visited daily by the leaders of the organisation. Damyan Velchev moved entirely into Georgiev's home. On 6 September, a permanent armed guard of several partisans, headed by Ivan Bonev, was posted there. Following the failure of General Ivan Marinov's attempt to peacefully change the government, a narrowed-down National Committee of the Fatherland Front decided to carry out a military coup at a meeting at the home of Kimon Georgiev on 7 September. At ten o'clock on the same day, a meeting of activists of the Military Union, led by Damyan Velchev, was held to coordinate the actions of the Union to carry out the coup.
== Early career == Shambhu Nath De was born in Hooghly District, West Bengal, India. His father Mr Dasarathi De was a not so successful businessman. Supported by his uncle Asutosh De, De completed the Matriculation examination with distinction from Garbati High School that helped him to get the District scholarship as well as to pursue further education in Hooghly Mohsin College, which was then affiliated with the prestigious University of Calcutta. His higher education was supported by Kestodhan Seth, who identified De as an extraordinary student. De passed his M.B. examination in 1939 from Calcutta Medical College and completed a Diploma in Tropical Medicine (DTM) in 1942. Soon after graduation he joined Calcutta Medical College as a Demonstrator of Pathology and initiated his research under Professor B. P. Tribedi. In 1947, De joined as a PhD student under Sir Roy Cameron at the Department of Morbid Anatomy, University College Hospital Medical School, London, and obtained his PhD degree in Pathology in 1949. After his return, De worked on pathogenesis of cholera and started publishing his findings. In 1955, De became the Head of Pathology and Bacteriology Division of the Calcutta Medical College, which he continued until his retirement. De published more than 30 research papers and has written an excellent monograph on cholera and its pathogenesis.
It thus represents an advantage over whole pancreas transplantation, which is more technically demanding and poses a risk of, for example, pancreatitis leading to organ loss. Another advantage is that patients do not require general anesthesia. Islet transplantation for type 1 diabetes (as of 2008) requires potent immunosuppression to prevent host rejection of donor islets. The islets are transplanted into a portal vein, which is then implanted in the liver. There is a risk of portal venous branch thrombosis and the low value of islet survival a few minutes after transplantation, because the vascular density at this site is after the surgery several months lower than in endogenous islets. Thus, neovascularization is key to islet survival, that is supported, for example, by VEGF produced by islets and vascular endothelial cells. However, intraportal transplantation has some other shortcomings, and so other alternative sites that would provide better microenvironment for islets implantation are being examined. Islet transplant research also focuses on islet encapsulation, CNI-free (calcineurin-inhibitor) immunosuppression, biomarkers of islet damage or islet donor shortage. An alternative source of beta cells, such insulin-producing cells derived from adult stem cells or progenitor cells would contribute to overcoming the shortage of donor organs for transplantation. The field of regenerative medicine is rapidly evolving and offers great hope for the nearest future. However, type 1 diabetes is the result of the autoimmune destruction of beta cells in the pancreas.
Sources: en.wikipedia.org
=== Wrongful death lawsuits === Carrey's girlfriend Cathriona White married Mark Burton in 2013, in Las Vegas. She and Carrey had been dating on and off since 2012, and she was still married but dating Carrey when she died in 2015. On September 19, 2016, Burton filed a wrongful death lawsuit against Carrey, claiming that he had used his "immense wealth and celebrity status" to illegally obtain and distribute prescription drugs involved in White's death. Carrey released a statement the following day:
Afamelanotide, sold under the brand name Scenesse, is a medication used to prevent phototoxicity and to reduce pain from light exposure for people with erythropoietic protoporphyria, a rare form of genetic sun sensitivity. Afamelanotide is a melanocortin 1 receptor (MC1 receptor) agonist and a synthetic peptide and analogue of α-melanocyte stimulating hormone. It is administered as subcutaneous implant.
lagging strand In DNA replication, the nascent strand for which DNA polymerase's direction of synthesis is away from the replication fork, which necessitates a complex and discontinuous process in contrast to the streamlined, continuous synthesis of the other nascent strand, known as the leading strand, which occurs simultaneously. Because DNA polymerase works only in the 5' to 3' direction, but the lagging strand's overall direction of chain elongation must ultimately be the opposite (i.e. 3' to 5', toward the replication fork), elongation must occur by an indirect mechanism in which a primase enzyme synthesizes short RNA primers complementary to the template DNA, and DNA polymerase then extends the primed segments into short chains of nucleotides known as Okazaki fragments. The RNA primers are then removed and replaced with DNA, and the Okazaki fragments are joined by DNA ligase.
Sanger then turned to sequencing DNA, which would require an entirely different approach. He looked at different ways of using DNA polymerase I from E. coli to copy single-stranded DNA. In 1975, together with Alan Coulson, he published a sequencing procedure using DNA polymerase with radiolabelled nucleotides that he called the "Plus and Minus" technique. This involved two closely related methods that generated short oligonucleotides with defined 3' termini. These could be fractionated by electrophoresis on a polyacrylamide gel and visualised using autoradiography. The procedure could sequence up to 80 nucleotides in one go and was a big improvement on what had gone before, but was still very laborious. Nevertheless, his group were able to sequence most of the 5,386 nucleotides of the single-stranded bacteriophage φX174. This was the first fully sequenced DNA-based genome. To their surprise they discovered that the coding regions of some of the genes overlapped with one another. In 1977 Sanger and colleagues introduced the "dideoxy" chain-termination method for sequencing DNA molecules, also known as the "Sanger method". This was a major breakthrough and allowed long stretches of DNA to be rapidly and accurately sequenced. It earned him his second Nobel prize in Chemistry in 1980, which he shared with Walter Gilbert and Paul Berg. The new method was used by Sanger and colleagues to sequence human mitochondrial DNA (16,569 base pairs) and bacteriophage λ (48,502 base pairs). The dideoxy method was eventually used to sequence the entire human genome.
1968–1973 – 1.0 L (985 cc) PB I4, 50 hp (37 kW; 51 PS) / 56 lb⋅ft (76 N⋅m) 1968–1970 – 1.2 L (1169 cc) TB I4, 58 hp (43 kW; 59 PS) / 69 lb⋅ft (94 N⋅m) 1970–1973 – 1.3 L (1272 cc) TC I4, 2-barrel, 69 hp (51 kW; 70 PS) / 67 lb⋅ft (91 N⋅m) The pickup received the BPB55, BTA55/65, or FA2T55/65/66 model codes respectively when fitted with the OHV 1.0 or 1.2, or the OHC 1.3. FA2T55 was a short bed with 500 kg (1,100 lb) max load, 65 was a long bed with the same capacity, while the 66 upped that to 600 kg (1,300 lb). All three models were available as either Standard or Deluxe. The 1000 Van (Japanese terminology for the station wagon, which was intended for commercial use there) received either BPCV or BPBV chassis codes, signifying three- or five-door versions. The Familia Presto Van, with OHC engines, received chassis numbers MP3xV/SP3xV for the 1000 (3-door/5-door) and MT2xV/ST2xV for the 1200. The five-door Van range was gradually expanded downwards as the three-door models dropped in popularity. The Familia Presto Van continued largely unchanged until the summer of 1978, aside from the 1.3 losing two horsepower along the way.
Sources: en.wikipedia.org
=== Lev–Ly === Phoebus Levene (1869–1940). Russian-American biochemist at the Rockefeller Institute, who discovered that DNA was composed of nucleobases and phosphate. Member Natl. Acad. Sci. USA. Cyrus Levinthal (1922–1990). American molecular biologist at Columbia, known for theoretical analysis of protein folding, and for Levinthal's paradox. Alexander Levitzki (b. 1940). Israeli biochemist at the Hebrew University of Jerusalem, known for developing specific chemical inhibitors of cancer-induced protein kinases. Member of the Israel Academy of Sciences and Humanities. Michael Levitt FRS (b. 1947). American-British-Israeli-South African biophysicist at Stanford. Nobel Prize in Chemistry (2013). Member Natl. Acad. Sci. USA. Choh Hao Li (1913–1987). Chinese-American biochemist at UC Berkeley. Known for discovering and synthesizing the human pituitary growth hormone. Academician of the Chinese Academy of Sciences (Academia Sinica). Member Natl. Acad. Sci. USA. Justus von Liebig (1803–1873). German scientist at the University of Giessen who made major contributions to agricultural and biological chemistry; one of the founders of organic chemistry. Hans Lineweaver (1907–2009). American physical chemist at the U.S. Department of Agriculture, known mainly for popularizing the double-reciprocal plot. Anthony William Linnane FRS (1930–2017). Australian biochemist at Monash University, known for work on mitochondria, and in particular for the relationship between mitochondrial damage and aging. Fellow of the Australian Academy of Science. Fritz Lipmann (1899–1986).
=== Temperature: Gas Mark === Gas Mark is a temperature scale, predominantly found on British ovens, that scales linearly with temperature above 135 °C (Gas Mark 1) and scales with the log of Celsius below 135 °C.
== Signs and symptoms == Symptoms may begin quickly or slowly depending on the size of the embolus and how much it blocks the blood flow. Symptoms of embolisation in an organ vary with the organ involved but commonly include:
During the night of 21 February, local sources in Afghanistan reported airstrikes in parts of Nangarhar, Paktika, and Khost provinces. In Nangarhar, strikes were reported in the Bihsud and Khogyani districts, while in Paktika, strikes were reported in the Barmal and Urgun districts. Local sources reported that the airstrikes in Nangarhar's Bihsud district struck a civilian home, trapping 23 people beneath the rubble. Pakistan's Ministry of Information and Broadcasting (MolB) stated that the Pakistani military conducted "intelligence-based selective targeting" of seven terrorist camps and hideouts along the Afghanistan-Pakistan border region. The Taliban claimed that the targets included civilian homes and a religious seminary. In a late-night press release, Pakistani officials confirmed that the Pakistan Air Force (PAF), under the command of Air Chief Marshal Zaheer Ahmad Babar, had carried out airstrikes in Afghanistan. Officials said the strikes were selective and intelligence-based, and targeted seven militant camps and hideouts linked to the Tehrik-i-Taliban Pakistan (TTP) and the Islamic State – Khorasan Province (ISIS–K) near the Afghanistan-Pakistan border. Pakistani officials added that the strikes were conducted as retaliation for recent terror attacks in Islamabad, Bajaur, and Bannu.
Sources: en.wikipedia.org
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.
The peptide enters plasma rapidly and is broken down by ordinary proteases into amino acids and shorter fragments. Reported half-lives are short. Whether meaningful amounts of the intact molecule reach the brain is an open question.
Most clinical reports are small, published in Russian and not independently replicated. English-language reviews highlight the absence of large randomised trials. Conclusions about efficacy should be treated as provisional.
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.