certificate of analysis raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-08-01 and is reviewed periodically as new material appears.
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.
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.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | 95 percent or higher by RP-HPLC | Area percentage of the main peak |
| Identity confirmation | Electrospray ionization mass spectrometry | Observed mass compared with the theoretical value near 751.9 Da |
| Recommended dry storage | -20 °C, desiccated | -80 °C for multi-year archival material |
| Solution handling | Prepare fresh; avoid long storage | Sterile filtration reduces microbial load |
| Common synonyms | TKPRPGP; TP-7 | Sequence code and laboratory designation used interchangeably |
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
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.
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.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
== Scholars == Clement Clarke Moore (1798), son of bishop Benjamin Moore; professor of Oriental and Greek literature; attributed author of The Night Before Christmas John Anthon (1801), jurist John Church Hamilton (1809), son of Alexander Hamilton, American historian Charles Anthon (1815), classical scholar and translator known for the Anthon Transcript Henry Drisler (1839), classical scholar and acting president of Columbia College Julius Sachs (1867), founder of Dwight School, professor at Teachers College, Columbia University and scion of the Goldman–Sachs family William Milligan Sloane (1868), historian, president of the American Academy of Arts and Letters and founder of the United States Olympic Committee Felix Adler (1870), professor of political and social ethics, founder of the Ethical Culture movement and the Ethical Culture Fieldston School Brander Matthews (1871), first professor of dramatic literature in the U.S. Charles Waldstein (A.M. 1873), Anglo-American archeologist, director of the Fitzwilliam Museum and American School of Classical Studies at Athens; first Jewish American athlete in the Olympic Games John Aaron Browning (1875), educator, founder of the Browning School Richard T. Ely (1876), economist, founder and president of the American Economic Association Edward Washburn Hopkins (1878), professor of Sanskrit at Yale University Edwin Robert Anderson Seligman (1879), economist William Archibald Dunning (1881), founder of the Dunning School of Reconstruction James Chidester Egbert Jr.
=== Valuation === Theranos raised millions of dollars in its first years. In 2004, Theranos was based in a rented basement near the Stanford campus. By December 2004, the company had raised more than $6 million from investors at a valuation of $30 million. The company had about $45 million total fundraising after Series B and Series C funding in 2006. Theranos raised an additional $45 million in 2010 at a valuation of $1 billion. The company had significant news coverage starting in September 2013 after profiles in the San Francisco Business Times and The Wall Street Journal. By 2014, Theranos had raised more than $400 million with an estimated value of $9 billion. Theranos raised more than $700 million from venture capitalists and private investors, resulting in a $10 billion valuation at its peak in 2013 and 2014. In 2016, Forbes revised the estimated net worth of the company to $800 million taking into account the $724 million of capital raised. Between 2004 and 2016, the amount of available cash from investors for private equity/venture capital firms to invest in companies grew from $400 billion to $1.5 trillion. It was a period of plentiful capital available where investors were pressured to find investment targets to deploy capital on. In the Theranos case, insufficient due diligence and fraudulent business practices led to the losses for investors. In May 2017, participating shareholders provided a release of any potential claims against Theranos in exchange for shares of the company's new preferred stock.
==== Males ==== CPA has been found to be effective in the treatment of acne in males, with marked improvement in symptoms observed at dosages of 25, 50, and 100 mg/day in different studies. It can also halt further progression of scalp hair loss in men. Increased head hair and decreased body hair has been observed with CPA in men with scalp hair loss. However, its side effects in men, such as demasculinization, gynecomastia, sexual dysfunction, bone density loss, and reversible infertility, make the use of CPA in males impractical in most cases. In addition, lower dosages of CPA, such as 25 mg/day, have been found to be better-tolerated in men. But such doses also show lower effectiveness in the treatment of acne in men.
Sources: en.wikipedia.org
N0: No facial nerve involvement N1: Upper facial nerve involvement (temporal or zygomatic branches) N2: Lower facial nerve involvement (buccal, mandibular or cervical) N3: All branches affected Soft tissue
The most medically important species of snake bites in Central Asia is the Caspian cobra (Naja oxiana). It is the most venomous species of cobra in the world, slightly ahead of the Philippine cobra based on a toxinological study from 1992 found in the Indian Journal of Experimental Biology, in which this species produced the highest potency venom among cobras. The venom of this species has the most potent composition of toxins found among any cobra species known. It is made up of primarily highly potent neurotoxins but it also has cytotoxic activity (tissue-death, necrosis) and cardiotoxins. Two forms of "cytotoxin II" (cardiotoxin) were found in the venom of this species. The crude venom of this species produced the lowest known lethal dose (LCLo) of 0.005 mg/kg, the lowest among all cobra species, derived from an individual case of poisoning by intracerebroventricular injection. According to Brown (1973), the subcutaneous LD99–100 value is 0.4 mg/kg, while Ernst and Zug et al. list a value of 0.21 mg/kg SC and 0.037 mg/kg IV. Latifi (1984) listed a subcutaneous value of 0.2 mg/kg (0.09–0.26 mg/kg). In another study, where venom was collected from a number of specimens in Iran, the Subcutis LD50 in lab mice was 0.078 mg/kg. Average venom yield per bite for this species is between 75 and 125 mg (dry weight), but it may yield up to 590 mg (dry weight) in a single bite. The bite of this species may cause severe pain and swelling, along with severe neurotoxicity.
The issue was laid to rest when the Empress interceded with the Imperial Fitwarari whose forces had cornered Negus Teferi with a few of his men in his home and were preparing to make short work of them. The Kebur Zabagna also had one heavy machine gun company. It was commanded by Ethiopian graduates of Saint Cyr, the French military academy, at the time of the Italian invasion of Ethiopia. As a unit, the Imperial Bodyguard only participated in the Battle of Maychew (31 March 1936), but afterwards many of its members joined the various groups of the Ethiopian resistance. Following the return of Emperor Haile Selassie to Ethiopia in 1941, the Kebur Zabagna was reconstituted, and a Swedish military mission aided in its training. Men for the Kagnew Battalion, which fought in the Korean War, were drawn from the Imperial Bodyguard.
==== Top-fed deep water culture ==== Top-fed deep water culture is a technique involving delivering highly oxygenated nutrient solution direct to the root zone of plants. While deep water culture involves the plant roots hanging down into a reservoir of nutrient solution, in top-fed deep water culture the solution is pumped from the reservoir up to the roots (top feeding). The water is released over the plant's roots and then runs back into the reservoir below in a constantly recirculating system. As with deep water culture, there is an airstone in the reservoir that pumps air into the water via a hose from outside the reservoir. The airstone helps add oxygen to the water. Both the airstone and the water pump run 24 hours a day. The biggest advantage of top-fed deep water culture over standard deep water culture is increased growth during the first few weeks. With deep water culture, there is a time when the roots have not reached the water yet. With top-fed deep water culture, the roots get easy access to water from the beginning and will grow to the reservoir below much more quickly than with a deep water culture system. Once the roots have reached the reservoir below, there is not a huge advantage with top-fed deep water culture over standard deep water culture. However, due to the quicker growth in the beginning, grow time can be reduced by a few weeks.
Sources: en.wikipedia.org
This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. In normal skin, the rate of production equals the rate of loss; about two weeks are needed for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum. The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary dermis and the reticular dermis. The superficial papillary dermis interdigitates with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. Structural components of the dermis are collagen, elastic fibers, and ground substance. Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing. The subcutaneous tissue is a layer of fat between the dermis and underlying fascia.
=== Transcriptional === Insulin acting via the sterol regulatory element binding protein-1c (SREBP1c) is thought to be the most important direct activator of glucokinase gene transcription in hepatocytes. SREBP1c is a basic helix-loop-helix zipper (bHLHZ) transactivator. This class of transactivators bind to the "E box" sequence of genes for a number of regulatory enzymes. The liver promoter in the first exon of the glucokinase gene includes such an E box, which appears to be the principal insulin-response element of the gene in hepatocytes. It was previously thought that SREBP1c must be present for transcription of glucokinase in hepatocytes however, it was recently shown that glucokinase transcription was carried out normally in SREBP1c knock out mice. SREBP1c increases in response to a high-carbohydrate diet, presumed as a direct effect of frequent insulin elevation. Increased transcription can be detected in less than an hour after hepatocytes are exposed to rising insulin levels. Fructose-2,6-bisphosphate (F2,6P2) also stimulates GK transcription, it seems by way of Akt2 rather than SREBP1c. It is not known whether this effect is one of the downstream effects of activation of insulin receptors or independent of insulin action. Levels of F2,6P2 play other amplifying roles in glycolysis in hepatocytes. Other transacting factors suspected of playing a role in liver cell transcription regulation include:
=== Postwar and Cold War === In 1947, the TA was restructured and expanded through the reactivation of some of the 1st Line divisions that were initially disbanded after the war, keeping its former role of supplying complete divisions to the regular Army until 1967. For the first time, TA units were formed in Northern Ireland. The maneuver divisions established or re-established in 1947 were:
Sources: en.wikipedia.org
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.
A reported purity value reflects the share of the main peak in one chromatographic run and says nothing about identity. Confirming that the expected sequence is present requires a separate measurement such as mass spectrometry. Purity and identity are distinct questions.
A mass spectrum reports the molecular masses present in a sample and shows whether they match the value expected for selank, near 751.9 Da. It also flags common artifacts such as truncation or adduct formation. It does not establish correct stereochemistry or complete sequence order on its own.
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.