Everything below concerns Research chemical. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-02-20. Numbers and descriptions here follow the published literature rather than marketing material.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
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.
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.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
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.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
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.
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.
=== CLP formation === In September 1974, CL members founded the CLP at a Congress in Chicago, Illinois. The newspaper of the CL, the Peoples Tribune/Tribuno del Pueblo, became the newspaper of the CLP. The CL's theoretical journal, Proletariat, was also continued by the CLP. In addition, the Western Worker, published by the CL was continued by the CLP. Nelson Peery was appointed leader
Formica polyctena, among other ant species, constructs nests that maintain a relatively constant interior temperature that aids in the development of larvae. The ants maintain the nest temperature by choosing the location, nest materials, controlling ventilation and maintaining the heat from solar radiation, worker activity and metabolism, and in some moist nests, microbial activity in the nest materials. Some ant species, such as those that use natural cavities, can be opportunistic and make use of the controlled micro-climate provided inside human dwellings and other artificial structures to house their colonies and nest structures.
However, patients with high tumor accumulation and multiple lesions seemed to benefit from 90Y-DOTATOC, while patients with low tumor burden, solitary lesions and extra-hepatic disease experienced more favorable outcome on 177Lu-DOTATOC. There were significantly fewer cases of transitory hematotoxicity in the 177Lu-DOTATOC group compared with the 90Y-DOTATOC group (1.4% versus 10.1%, p=0.001). The randomized controlled phase III Neuroendocrine Tumors Therapy (NETTER-1) trial evaluated the efficacy and safety of 177Lu-DOTATATE as compared with high-dose octreotide long-acting repeatable (LAR) in patients with advanced progressive somatostatin-receptor positive midgut neuroendocrine tumors. Patients were randomly assigned to receive either 177Lu-DOTATATE and octreotide LAR at a dose of 30 mg every four weeks for symptom control (n=116) or to only receive octreotide LAR at a dose of 60 mg every four weeks (n=113, control group). In total, 200 out of the 231 patients entered long-term follow-up. Final overall survival in the intention-to-treat population was median 48.0 months in the 177Lu-DOTATATE group versus median 36.3 months in the control group (p=0.30). In other words, there was numerical difference of 11.7 months, not reaching statistical significance. 177Lu-DOTATATE was associated with limited acute toxic effects. In neuroendocrine tumor patients with advanced well-differentiated disease and progression on somatostatin analogs, 177Lu-DOTATATE is likely to reduce the risk of disease progression and be associated with quality-of-life benefits.
Endometrium: the mucosa of the uterus Gastric mucosa Intestinal mucosa Nasal mucosa Olfactory mucosa Oral mucosa Penile mucosa Respiratory mucosa Vaginal mucosa Frenulum of tongue Anal canal Conjunctiva
==== Short-term ==== Acute adverse effects are usually the result of high or multiple doses, although single dose toxicity can occur in susceptible individuals. The most serious short-term physical health risks of MDMA are hyperthermia and dehydration. Cases of life-threatening or fatal hyponatremia (excessively low sodium concentration in the blood) have developed in MDMA users attempting to prevent dehydration by consuming excessive amounts of water without replenishing electrolytes. The immediate adverse effects of MDMA use can include:
Sources: en.wikipedia.org
== Overview and assessment of Kermani’s literary work by Torsten Hoffmann == Torsten Hoffmann, a literary scholar, a professor at the University of Stuttgart, and a recognized and long-standing expert on Kermani's extensive literary work, classifies Kermani’s narrative work as follows: Most of Kermani’s literary texts draw on an auto-fictionalapproach (in his most extensive novel, „Dein Name“ [Your Name], the protagonist is also named “Navid Kermani”). Furthermore, they are characterizing by a particular interest in fundamental human experiences such as birth, love, and death, along with a programmatic combination of (sometimes drastic) everydayness with an affinity for art (including literature, music, film, and the visual arts) and religiosity. The boundaries between his works of fiction and works more commonly regarded as nonfiction (such as „Ungläubiges Staunen“ (Wonder Beyond Belief) or „Jeder soll von da, wo er ist, einen Schritt näher kommen“ (Everyone, Wherever You Are, Come One Step Closer) and travelogues are fluid. For while Kermani’s nonfiction books often employ literary narrative techniques, conversely, many of his works of fiction contain essayistic passages.
==== Food and Drug Administration (FDA) ==== The FDA reviews commercially available test kits and their associated medical claims to ensure safety and efficacy before products are cleared or approved for use. The regulatory landscape for laboratory developed tests (LDTs) has been evolving significantly. On May 6, 2024, the FDA issued a final rule significantly modifying its approach to oversight of laboratory-developed tests, amending regulations to clarify that in vitro diagnostic products (IVDs) are devices under the Federal Food, Drug, and Cosmetic Act, including when manufactured by a laboratory. The final rule includes a policy under which FDA would phase out enforcement discretion for LDTs over a four-year period. The phaseout policy consists of five stages, starting May 6, 2024. DTC tests are specifically noted as having never been subject to enforcement discretion, meaning compliance with FDA requirements has always been expected for consumer-facing diagnostic tests. However, on April 17, 2025, a federal court blocked FDA's final rule on LDTs, creating uncertainty about the regulatory future. LDTs continue to be governed by CMS under CLIA oversight, but the long-term regulatory framework remains unsettled.
Some proteins are synthesized by nonribosomal peptide synthetases, which can be big protein complexes, each specializing in synthesizing only one type of peptide. Nonribosomal peptides often have cyclic or branched structures and can contain non-proteinogenic amino acids – both of these factors differentiate them from ribosome synthesized proteins. An example of nonribosomal peptides are some of the antibiotics.
Tyrannosaurus, like most dinosaurs, was long thought to have an ectothermic ("cold-blooded") reptilian metabolism. The idea of dinosaur ectothermy was challenged by scientists like Robert T. Bakker and John Ostrom in the early years of the "dinosaur renaissance", beginning in the late 1960s. T. rex itself was claimed to have been endothermic ("warm-blooded"), implying a very active lifestyle. Since then, several paleontologists have sought to determine the ability of Tyrannosaurus to regulate its body temperature. Histological evidence of high growth rates in young T. rex, comparable to those of mammals and birds, may support the hypothesis of a high metabolism. Growth curves indicate that, as in mammals and birds, T. rex growth was limited mostly to immature animals, rather than the indeterminate growth seen in most other vertebrates. Oxygen isotope ratios in fossilized bone are sometimes used to determine the temperature at which the bone was deposited, as the ratio between certain isotopes correlates with temperature. In one specimen, the isotope ratios in bones from different parts of the body indicated a temperature difference of no more than 4 to 5 °C (7 to 9 °F) between the vertebrae of the torso and the tibia of the lower leg. This small temperature range between the body core and the extremities was claimed by paleontologist Reese Barrick and geochemist William Showers to indicate that T. rex maintained a constant internal body temperature (homeothermy) and that it enjoyed a metabolism somewhere between ectothermic reptiles and endothermic mammals.
== External links == How wounds heal and tumors form With this simple Flash demonstration, Harvard professor Donald Ingber explains how wounds heal, why scars form, and how tumors develop. Presented by Children's Hospital Boston. Wound Healing and Repair Lorenz H.P. and Longaker M.T. Wounds: Biology, Pathology, and Management. Stanford University Medical Center. Romo T. and McLaughlin L.A. 2003. Wound Healing, Skin. Emedicine.com. Rosenberg L. and de la Torre J. 2003. Wound Healing, Growth Factors. Emedicine.com. After the Injury- Children's Hospital Of Philadelphia
Sources: en.wikipedia.org
==== Production ==== Animal hides are soaked in water to produce "stock". The stock is then treated with lime to break down the hides. The hides are then rinsed to remove the lime, any residue being neutralized with a weak acid solution. The hides are heated, in water, to a carefully controlled temperature around 70 °C (158 °F). The "glue liquor" is then drawn off, more water added, and the process repeated at increasing temperatures. The glue liquor is then dried and chipped into pellets.
Laidlaw stated that reasons behind the cancellation included the fact that headcrabs and zombies "were pretty much played out at the time", and that the fact that it had to take place chronologically prior to Half-Life 2: Episode Two was too creatively constraining. Footage of the project was shown in a 2020 documentary by media company Noclip titled The Untold History of Arkane.
The secondary drying phase aims to remove unfrozen water molecules, since the ice was removed in the primary drying phase. This part of the freeze-drying process is governed by the material's adsorption isotherms. In this phase, the temperature is raised higher than in the primary drying phase, and can even be above 0 °C (32 °F), to break any physico-chemical interactions that have formed between the water molecules and the frozen material. Usually the pressure is also lowered in this stage to encourage desorption (typically in the range of microbars, or fractions of a pascal). However, there are products that benefit from increased pressure as well. After the freeze-drying process is complete, the vacuum is usually broken with an inert gas, such as nitrogen, before the material is sealed. At the end of the operation, the final residual water content in the product is extremely low, around 1–4%.
Liu's governance of Sichuan was challenged by various natural disasters, exacerbated by war. The National Gazette reported the existence of famine in Shunqing and Jintang, as well as other areas of the province. The measures Liu took to address these crises are not known. Liu Wenhui continued his emphasis on promoting education, founding the Jianguo Middle School in Chengdu and serving as its chairman. The school reportedly had high academic standards and included stringent political training. Geographically, the wealthiest and most productive areas in central Sichuan were under Liu Wenhui's sway. This included Chengdu, but also the important salt production centers of Zilujing-Gongjing and the major river port of Yibin, as well as other agricultural and commercial facilities across the Chengdu Plain. Control of the lucrative Yunnan-Sichuan of opium, salt, and weapons in Yibin in particular was dominated by his older brother Liu Wencai, who was a key part of Liu's government. Liu funded some of his garrisons with the salt tax of Leshan, earning around 800 taels per month. These resources helped sustain Liu's armies and secure his power base.
To facilitate the work of the CDC, a Medical Laboratory Services Advisory Committee was appointed. Inhorn was the only State Laboratory Director to serve on the MLSAC Advisory Committee, perhaps because the WSLH had a strong history of proficiency testing in clinical laboratories in Wisconsin. Inhorn's assignment for CLIA-67 was to develop a protocol for PT programs to be used in the future. Many changes had been made to CLIA-67, but major weaknesses in the program still existed. It would take another two decades before new federal legislation, called CLIA-88, would address these shortcomings. Inhorn was appointed to the new CLIA-88 advisory board and served during the first two years of its existence. During the ensuing years, many more health laboratories opened in the U.S. and new technology introduced built-in controls, so that performance was validated without confirmation by laboratory workers.
Sources: en.wikipedia.org
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.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.