If you have been reading about lyophilization and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-10-22. Numbers and descriptions here follow the published literature rather than marketing material.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Modeled on tuftsin |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues |
| Approximate molecular mass | Around 750 Da | Depends on counter-ion and hydration |
| Common forms | Lyophilized powder | Also described as aqueous solution |
| Primary origin of research | Russian laboratories | Mid-1990s onward |
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.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
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.
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.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Historically, men's pain has been treated as abnormal and requiring medical intervention, while women's pain, especially related to menstruation and childbirth, was considered normal and often left untreated. The perception of menstruation-related pain as natural—sometimes reinforced by religious narratives—contributed to this neglect. Pain relief in childbirth gradually advanced, with chemical anesthesia introduced in the 19th century, and techniques such as pain-free childbirth in 1950s France. Epidural anesthesia became common from the 1980s onward. Menstrual pain and conditions like endometriosis (affecting around 10% of women) have only been widely recognized by the medical profession since the late 2010s. Endometriosis was officially recognized as a medical condition in France in 1990. A national awareness plan was launched in 2019, and the disease was classified as a long-term illness in 2022. Some studies suggest that women may delay seeking care, often prioritizing family responsibilities and underestimating their symptoms.
Dermatomyositis (DM) is a group of systemic autoimmune inflammatory diseases primarily affecting the skin and skeletal muscles. Its symptoms are generally a skin rash and worsening muscle weakness over time. These may occur suddenly or develop over months. Other symptoms may include weight loss, fever, lung inflammation, or light sensitivity. Complications may include calcium deposits in muscles or skin. Distinct myositis-specific autoantibodies (MSA) define clinically and pathologically distinct DM subtypes, each associated with characteristic disease manifestations, prognosis, and treatment response. Eighty percent of adults and sixty percent of children with juvenile dermatomyositis have a MSA. These autoantibodies, produced by locally infiltrating plasma cells, can enter various cell types and disrupt the function of their target autoantigens, inducing cellular damage and inflammation that directly drive disease pathogenesis. Dermatomyositis may develop as a paraneoplastic syndrome associated with several malignancies, in which tumors harbor genetic alterations, including somatic mutations, in genes encoding the specific autoantigens targeted by the patient's corresponding autoantibodies. It is known to be associated with several viruses, especially coxsackievirus, but no definitive causal link has been found. Diagnosis is typically based on some combination of symptoms, blood tests, electromyography, and muscle biopsies.
Heart muscle is striated muscle but is distinct from skeletal muscle because the muscle fibers are laterally connected. Furthermore, just as with smooth muscles, their movement is involuntary. Heart muscle is controlled by the sinus node influenced by the autonomic nervous system.
Several methods have been proposed for PET-MRI attenuation coefficient, including machine learning, algorithms to directly estimate attenuation coefficients from the MRI or emission data, and atlas-based approaches (where the MRI scan is co-registered with a database of CT images). While attenuation-corrected images are generally more faithful representations, the correction process is itself susceptible to significant artifacts. As a result, both corrected and uncorrected images are often reconstructed and read together. 2D/3D reconstruction: Early PET scanners had only a single ring of detectors, hence the acquisition of data and subsequent reconstruction was restricted to a single transverse plane. More modern scanners now include multiple rings, essentially forming a cylinder of detectors. There are two approaches to reconstructing data from such a scanner:
Sources: en.wikipedia.org
In the UK (2013) DMEK is available to patients under the National Health Service at the Royal Shrewsbury Hospital, the Calderdale and Huddersfield NHS Trust, and at Worthing Hospital (Western Sussex Hospitals NHS Foundation Trust). Not all patients with diseased corneas are candidates for endothelial keratoplasty. These procedures correct corneal endothelial failure, but are not able to correct corneal scarring, thinning, or surface irregularity. There is currently limited data on long-term survival of DMEK grafts however the early indications are very positive. An upcoming systematic review will seek to compare the safety and effectiveness of DMEK versus DSAEK in people with corneal failure from Fuchs' endothelial dystrophy and pseudophakic bullous keratopathy.
=== Calculated atomic and physical properties === Oganesson is a member of group 18, the zero-valence elements. The members of this group are usually inert to most common chemical reactions (for example, combustion) because the outer valence shell is completely filled with eight electrons. This produces a stable, minimum energy configuration in which the outer electrons are tightly bound. It is thought that similarly, oganesson has a closed outer valence shell in which its valence electrons are arranged in a 7s27p6 configuration. Consequently, some expect oganesson to have similar physical and chemical properties to other members of its group, most closely resembling the noble gas above it in the periodic table, radon. Following the periodic trend, oganesson would be expected to be slightly more reactive than radon. However, theoretical calculations have shown that it could be significantly more reactive. In addition to being far more reactive than radon, oganesson may be even more reactive than the elements flerovium and copernicium, which are heavier homologs of the more chemically active elements lead and mercury, respectively. The reason for the possible enhancement of the chemical activity of oganesson relative to radon is an energetic destabilization and a radial expansion of the last occupied 7p-subshell. More precisely, considerable spin–orbit interactions between the 7p electrons and the inert 7s electrons effectively lead to a second valence shell closing at flerovium, and a significant decrease in stabilization of the closed shell of oganesson.
However, in December 2016, the US took steps to reinstate retaliatory tariffs given continued concerns about EU market access, and in August 2019 they agreed to establish an initial duty-free tariff-rate quota of 18,500 tonnes annually, growing in phases over seven years to 35,000 tonnes (valued at approximately US$420 million) of the EU 45,000 tonnes quota of non-hormone treated beef.
If a lich's corporeal body is destroyed, the portion of its soul that remained in the body does not pass on to the afterlife; rather, it persists in a non-corporeal form capable of being reconstituted or resurrected. However, if all of a lich's soul-artifacts are destroyed, its only remaining anchor to the material world becomes its corporeal body—meaning that its destruction would result in permanent death.
of stoichiometric iron pyrite FeS2 amounts to 541.87 pm. The unit cell is composed of a Fe face-centered cubic sublattice into which the S2 ions are embedded. (Note though that the iron atoms in the faces are not equivalent by translation alone to the iron atoms at the corners.) The pyrite structure is also seen in other MX2 compounds of transition metals M and chalcogens X = O, S, Se and Te. Certain dipnictides with X standing for P, As and Sb etc. are also known to adopt the pyrite structure. The Fe atoms are bonded to six S atoms, giving a distorted octahedron. The material is a semiconductor. The Fe ions are usually considered to be low spin divalent state (as shown by Mössbauer spectroscopy as well as XPS). The material as a whole behaves as a Van Vleck paramagnet, despite its low-spin divalency. The sulfur centers occur in pairs, described as S2−2. Reduction of pyrite with potassium gives potassium dithioferrate, KFeS2. This material features ferric ions and isolated sulfide (S2−) centers. The S atoms are tetrahedral, being bonded to three Fe centers and one other S atom. The site symmetry at Fe and S positions is accounted for by point symmetry groups C3i and C3, respectively. The missing center of inversion at S lattice sites has important consequences for the crystallographic and physical properties of iron pyrite. These consequences derive from the crystal electric field active at the sulfur lattice site, which causes a polarization of S ions in the pyrite lattice.
Sources: en.wikipedia.org
=== Introduction of nylon blends === As pure nylon hosiery was sold in a wider market, problems became apparent. Nylon stockings were found to be fragile, in the sense that the thread often tended to unravel lengthwise, creating 'runs'. People also reported that pure nylon textiles could be uncomfortable due to nylon's lack of absorbency. Moisture stayed inside the fabric near the skin under hot or moist conditions instead of being "wicked" away. Nylon fabric could also be itchy and tended to cling and sometimes spark as a result of static electrical charge built up by friction. Also, under some conditions, nylon could degrade, perforating or shredding stockings. Scientists explained this as acid hydrolysis resulting from air pollution, attributing it to London smog in 1952, as well as poor air quality in New York and Los Angeles. The solution found to problems with pure nylon fabric was to blend nylon with other existing fibers or polymers such as cotton, polyester, and spandex. This led to the development of a wide array of blended fabrics. The new nylon blends retained the desirable properties of nylon (elasticity, durability, ability to be dyed) and kept clothes prices low and affordable. As of 1950, the New York Quartermaster Procurement Agency (NYQMPA), which developed and tested textiles for the Army and Navy, had committed to developing a wool-nylon blend. They were not the only ones to introduce blends of both natural and synthetic fibers. America's Textile Reporter referred to 1951 as the "Year of the blending of the fibres".
== Pathophysiology == The recognised forms of MODY are all due to ineffective insulin production or release by pancreatic beta cells. Several of the defects are mutations of transcription factor genes. One form is due to mutations of the glucokinase gene. For each form of MODY, multiple specific mutations involving different amino acid substitutions have been discovered. In some cases, there are significant differences in the activity of the mutant gene product that contribute to variations in the clinical features of the diabetes (such as degree of insulin deficiency or age of onset).
RO5073012 is a selective low-efficacy partial agonist of the trace amine-associated receptor 1 (TAAR1) which has been used in scientific research. TAAR1 partial agonists like RO5073012 can have agonist- or antagonist-like effects at the TAAR1 depending on the context and level of TAAR1 signaling.
=== Distillation === When distilled, cider turns into fruit brandy. Calvados is the apple brandy traditional to the France Normandy region, while Applejack is the traditional North American cider distillate.
Sources: en.wikipedia.org
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.
It originates from research in Russia, associated with the Institute of Molecular Genetics of the Russian Academy of Sciences. The first descriptions date to the mid-1990s. Most published studies come from Russian laboratories.
No, Selank itself does not occur naturally. Its backbone is based on tuftsin, which is produced in the body, but the seven-residue version is a synthetic construct. It is supplied as a manufactured peptide.
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.