Lyophilisation is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-04-06. Numbers and descriptions here follow the published literature rather than marketing material.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
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 |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
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.
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.
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.
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.
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.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
==== Natural analogues ==== Natural analogues of nicotine, often found in plants or other biological sources, include anabasine (from Anabasis aphylla), anatabine (from tobacco), arecoline (from betel nut), cotinine (major metabolite of nicotine), cytisine (from Laburnum species), and epibatidine (from frog skin), among others.
The Aga Khan University Hospital (AKUH) is a private hospital in Karachi, Pakistan. Established in 1985, it is the primary academic medical centre of the Aga Khan University. The hospital provides quaternary care, including multidisciplinary care across all clinical specialities.[1]
The idea that life originated from non-living matter in slow stages appeared in Herbert Spencer's 1864–1867 book Principles of Biology, and in William Turner Thiselton-Dyer's 1879 paper "On spontaneous generation and evolution". On 1 February 1871 Charles Darwin wrote about these publications to Joseph Hooker, and set out his own speculation that the original spark of life may have been in a "warm little pond, with all sorts of ammonia and phosphoric salts,—light, heat, electricity &c present, that a protein compound was chemically formed". Darwin explained that "at the present day such matter would be instantly devoured or absorbed, which would not have been the case before living creatures were formed." Alexander Oparin in 1924 and J. B. S. Haldane in 1929 proposed that the earliest cells slowly self-organized from a primordial soup, the Oparin–Haldane hypothesis. Haldane suggested that the Earth's prebiotic oceans consisted of a "hot dilute soup" in which organic compounds could have formed. J. D. Bernal showed that such mechanisms could form most of the necessary molecules for life from inorganic precursors. In 1967, he suggested three "stages": the origin of biological monomers; the origin of biological polymers; and the evolution from molecules to cells.
== Further reading == Ahmad, Diana L. The Opium Debate and Chinese Exclusion Laws in the Nineteenth-century American West (University of Nevada Press, 2007). Drugs and Racism in the Old West. Armero and Rapaport. The Arts of an Addiction. Qing Dynasty Opium Pipes and Accessories (privately printed, 2005) Auerbach, Sascha. Race, Law and 'The Chinese Puzzle' in Imperial Britain. New York: Palgrave-Macmillan Press, 2009. Booth, Martin. Opium: A History. London: Simon & Schuster, Ltd., 1996. Chandra, Siddharth (2008). "Economic Histories of the Opium Trade". Archived from the original on September 28, 2013. Retrieved November 9, 2008. Chouvy, P.A. (2009). "Opium. Uncovering the Politics of the Poppy, London, I.B. Tauris (Cambridge, Harvard University Press: 2010)". Archived from the original on October 26, 2011. Retrieved October 20, 2009. Day, Horace B. (1868). The Opium Habit. de Quincey, Thomas (1821). Confessions of an English opium-eater. Standard Ebooks. Derks, Hans: History of the Opium Problem: The Assault on the East, ca. 1600–1950. Sinica Leidensia, 105. Leiden: Brill, 2012. ISSN 0169-9563. ISBN 978-90-04-22158-1 Dikötter, Frank, Lars Laamann, and Zhou Xun. Narcotic culture: a history of drugs in China Chicago: University of Chicago Press, 2004. Dormandy, Thomas (2012) Opium: Reality's Dark Dream, Yale University Press Fairbank, J.K. (1978) The Cambridge History of China: volume 10 part I, Cambridge, CUP Franck Daninos, L'opium légal produit en France, La Recherche, May 2005 Great Britain (1913).
Sources: en.wikipedia.org
==== 2000-2009 ==== In 2000, Teva acquired Canada-based Novopharm. In October 2003, Teva announced its intentions to acquire Sicor Inc. for $3.4 billion. Following the announcement, the acquisition was completed on January 22, 2004, which marked Teva's entry into biosimilars' market. In 2005, Teva opened a new, state-of-the-art pharmaceutical manufacturing plant in Har Hotzvim, a technology park in Jerusalem. The plant received FDA approval in early 2007. Teva entered the Japanese market in 2005 and in 2008 established a generics joint venture with Kowa. In January 2006, Teva acquired its U.S. rival Ivax Corporation for $7.4 billion. In 2008, sales totalled $11.08 billion, $13.9 billion in 2009, and in 2010 total sales rose to $16.1 billion, of which a major portion was in Europe and North America. In July 2008, Teva announced it completed the acquisition of Bentley Pharmaceuticals for its generic pharmaceutical operations in Spain for $360 million in cash. On December 23, 2008, Teva acquired Barr Pharmaceuticals for $7.5 billion, making Barr and Pliva (which Barr bought earlier) part of Teva.
=== Taste === People who can taste phenylthiocarbamide (PTC), which is either bitter or tasteless, are less likely to find cruciferous vegetables palatable due to the resemblance between isothiocyanates and PTC.
=== Powder feeding in continuous manufacturing === In continuous manufacturing, input raw materials and energy are fed into the system at a constant rate, and at the same time, a constant extraction of output products is achieved. The process's performance is heavily dependent on the stability of the material flowrate. For powder-based continuous processes, it is critical to feed powders consistently and accurately into subsequent unit operations of the process line, as feeding is typically the first unit operation. Feeders have been designed to achieve performance reliability, feed rate accuracy, and minimal disturbances. Accurate and consistent delivery of materials by well-designed feeders ensures overall process stability. Loss-in-weight (LIW) feeders are selected for pharmaceutical manufacturing. Loss-in-weight (LIW) feeders control material dispensing by weight at a precise rate and are often selected to minimize the flowrate variability that is caused by change of fill level and material bulk density. Importantly, feeding performance is strongly dependent on powder flow properties.
== Early life and education == Fred McLafferty was born in Evanston, Illinois in 1923, but attended grade school in Omaha, Nebraska, graduating from Omaha North High School in 1940. The urgent requirements of World War II accelerated his undergraduate studies at the University of Nebraska; he obtained his B.S. degree in 1943 and thereafter entered the US armed forces. He served in western Europe during the invasion of Germany and was awarded the Combat Infantryman Badge, a Purple Heart, five Bronze Star Medals and a Presidential Unit Citation. He returned to the University of Nebraska in late 1945 and completed his M.S. degree in 1947. He went on to work under William Miller at Cornell University where he earned his Ph.D. in 1950. He went on to a postdoctoral researcher position at the University of Iowa with R.L. Shriner.
==== United Arab Emirates ==== The UAE has been a center for political oriented think tanks which concentrate on both regional and global policy. Notable think tank have emerged in the global debate on terrorism, education & economical policies in the MENA region. Think tanks include:
Sources: en.wikipedia.org
This amount increased significantly during the 1999–2003 period, when the costs generated by the reconstruction of the bridges represented $18,455.7 million. These costs are equivalent to 1.71% of the total INVÍAS budget for 2003. For 2004, costs for damage to road infrastructure dropped substantially to $680 million. The partial interruption of the roads directly affects the transport sector, food, and other private guilds, which in turn assume costs for these damages. However, generally these have not been quantified because of the difficulty they pose for being directly calculated. This presents the generalized problem of quantifying the costs associated with conflict. This is explained, in part, by the tendency in the various economic sectors not to denounce these types of actions that, in one way or another, interrupt the normal functioning of economic activities.
Autologous: The donor skin is taken from a different site on the same individual's body (also known as an autograft). Isogeneic: The donor and recipient individuals are genetically identical (e.g., monozygotic twins, animals of a single inbred strain; isograft or syngraft). Allogeneic: The donor and recipient are of the same species (human→human, dog→dog; allograft). Xenogeneic: The donor and recipient are of different species (e.g., bovine cartilage; pig skin; xenograft or heterograft). Prosthetic: Lost tissue is replaced with synthetic materials such as metal, plastic, or ceramic (prosthetic implants). Allografts, xenografts, and prosthetic grafts are usually used as temporary skin substitutes, that is a wound dressing for preventing infection and fluid loss. They will eventually need to be removed as the body starts to reject the foreign material. Autologous grafts and some forms of treated allografts can be left on permanently without rejection. Genetically modified pigs can produce allograft-equivalent skin material, and tilapia skin is used as an experimental cheap xenograft in places where porcine skin is unavailable and in veterinary medicine. By thickness:
Since the 1990s, large cities across China have moved traditional outdoor markets to modern indoor facilities. As of 2018, fresh food markets remained the most prevalent food outlet in urban regions of China despite the rise of supermarket chains since the 1990s. During the 2010s, "smart markets" equipped with e-payment terminals emerged as traditional markets faced increasing competition from discount stores. Such markets also began facing competition from online grocery stores, such as Alibaba's Hema stores. The trade of wildlife is not common in China, particularly in large cities, and most food markets in China do not contain live or wild animals besides fish held in tanks. In the early 1980s, small-scale wildlife farming began under the reform and opening up. It began to expand nationwide with government support in the 1990s, but was largely concentrated in the southeastern provinces. In 2003, markets across China were banned from holding wildlife after the 2002–2004 SARS outbreak, which was directly tied to such practices. Some poorly regulated Chinese markets provided outlets for the wildlife trade industry after the ban, although the illegal wildlife trade in China was predominantly in fur rather than in food or medicine. The Huanan Seafood Wholesale Market in Wuhan was linked to the origin of COVID-19 due to its early cluster of cases, leading to further restrictions and enforcement in 2020. In April 2020, the Chinese government unveiled plans to further tighten restrictions on wildlife trade.
Its down-regulation with siRNA inhibits SeV infection of Hep G2 cells. The cell fusion property of SeV was utilized by Köhler and Milstein, who published an article in 1975 outlining a revolutionary method of manufacturing monoclonal antibodies. In need of a reliable method to produce large quantities of a specific antibody, the two merged a monoclonal B cell, exposed to a chosen antigen, and a myeloma tumor cell to produce hybridomas, capable of being grown indefinitely and of producing significant amounts of an antibody specifically targeting the chosen antigen. Though more efficient methods of creating such hybrids have since been found, Köhler and Milstein first used Sendai virus to create their revolutionary cells.
=== CDISC === The Clinical Data Interchange Standards Consortium leads the development of global, system independent data standards which are now commonly used as the underlying data structures for clinical trial data. These describe parameters such as the name, length and format of each data field (variable) in the relational database.
Sources: en.wikipedia.org
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
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.