If you have been reading about mass spectrometry 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 2025-11-30. Numbers and descriptions here follow the published literature rather than marketing material.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
| Property | Value | Notes |
|---|---|---|
| Route studied | Intranasal | Predominant route in published reports |
| Circulation stability | Short, minutes scale | Peptidases cleave it; the tail slows the process |
| Analytical method | RP-HPLC with mass spectrometry | Used for identity and purity assessment |
| Reported outcome domains | Anxiety and cognitive measures | Derived from small, mostly regional trials |
| Regulatory status | Marketed in Russia | Availability outside that market is limited |
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
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.
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.
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.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
==== Somatostatin analogues ==== The primary medical treatment of acromegaly is to use somatostatin analogues – octreotide (Sandostatin) or lanreotide (Somatuline). Somatostatin analogues are also sometimes used to shrink large tumors before surgery. Because octreotide inhibits gastrointestinal and pancreatic function, long-term use causes digestive problems such as loose stools, nausea, and gas in one-third of people. In addition, approximately 25 percent of people with acromegaly develop gallstones, which are usually asymptomatic. In some cases, octreotide treatment can cause diabetes because somatostatin and its analogues can inhibit the release of insulin. With an aggressive adenoma that is not able to be operated on, there may be a resistance to octreotide in which case a second-generation SSA, pasireotide, may be used for tumor control. However, insulin and glucose levels should be carefully monitored as pasireotide has been associated with hyperglycemia by reducing insulin secretion.
==== Non-Hodgkin lymphoma ==== Results from several studies indicate that, compared to other autoimmune diseases, Sjögren's disease is associated with a notably high incidence of non-Hodgkin lymphoma, a cancer of white blood cells. About 5% of patients with Sjögren's develop some form of lymphoid malignancy. Patients with severe cases are much more likely to develop lymphomas than patients with mild or moderate cases. The most common lymphomas are salivary extranodal marginal zone B cell lymphomas (MALT lymphomas in the salivary glands) and diffuse large B-cell lymphoma. Lymphomagenesis in primary Sjögren's disease patients is considered a multistep process, with the first step being chronic stimulation of autoimmune B cells, especially B-cells that produce rheumatoid factor at sites targeted by the disease. This increases the frequency of oncogenic mutation, leading to any dysfunction at checkpoints of autoimmune B-cell activation to transform into malignancy. A study's findings concluded that continuous stimulation of autoimmune B cells leads to subtle germinal abnormalities in genes having specific consequences in B cells, which underlie the susceptibility to lymphoma.
=== After age 35 === After age 35, acquired coronary artery disease predominates (80%), and this is true regardless of the athlete's former level of fitness. Various performance-enhancing drugs can increase cardiac risk, though evidence has been inconclusive about their involvement in sudden cardiac deaths.
==== Stems ==== Young lotus stems are used as a salad ingredient in Vietnamese cuisine and as a vegetable ingredient for some soup and curry in Thailand, such as keang som sai bua (Thai: แกงส้มสายบัว, lotus stem sour soup) and keang kati sai bua (แกงกะทิสายบัว, lotus stem in coconut milk curry). In northern and eastern regions of India, the stalk of the flower is used to prepare a soup, kamala gaṭṭē kī sabzī (Hindi: कमल गट्टे की सब्ज़ी) and an appetizer, kamala kakaṛī pakauṛē (Hindi: कमल ककड़ी पकौड़े). In South Indian states, the lotus stem is sliced, marinated with salt to dry, and the dried slices are fried and used as a side dish. In Kerala (Malayalam: താമര) and Tamil Nadu, this end product is called thamara vathal. In the Philippines, an indigenous variety called tukal is used as the main ingredient in dishes with coconut milk. The stems and petals can be bought in markets when in season.
== March == 1 March to 14 April Operation Wayne Grey was conducted by the 1st Brigade, 4th Infantry Division in the Plei Trap Valley, Kontum Province. The operation resulted in 575 PAVN killed and four captured, U.S. losses were 106 killed and one missing.
Sources: en.wikipedia.org
AMPylation of the IbpA Fic domain of Rho family GTPases is responsible for its cytotoxicity. Both Fic domains have similar effects on host cells' cytoskeleton as VopS. The AMPylation on a tyrosine residue of the switch 1 region blocks the interaction of the GTPases with downstream substrates such as PAK. DrrA is the Dot/Icm type IV translocation system substrate DrrA from Legionella pneumophila. It is the effector secreted by L. pneumophila to modify GTPases of the host cells. This modification increases the survival of bacteria in host cells. DrrA is composed of Rab1b specific guanine nucleotide exchange factor (GEF) domain, a C-terminal lipid binding domain and an N-terminal domain with unclear cytotoxic properties. Research works show that N-terminal and full-length DrrA shows AMPylators activity toward host's Rab1b protein (Ras related protein), which is also the substrate of Rab1b GEF domain. Rab1b protein is the GTPase Rab to regulate vesicle transportation and membrane fusion. The adenylation by bacteria AMPylators prolong GTP-bound state of Rab1b. Thus, the role of effector DrrA is connected toward the benefits of bacteria's vacuoles for their replication during the infection.
Aldosterone is a mineralocorticoid which is synthesized in the adrenal glands. When aldosterone is secreted from the adrenal glands, it binds to the mineralocorticoid receptor in the renal tubule cell and forms a complex. This complex enhances transcription of specific DNA segments in the nucleus, leading to the formation of two protein transporters, Na+/K+ ATPase pump at the basolateral membrane and Na+ channel called ENaC, located at the apical membrane of the renal tubule cell. These protein transporters increase sodium reabsorption and potassium excretion in the distal tubule and the collecting duct of the kidneys. This helps the body to maintain normal volume and electrolyte balance, increasing the blood pressure. Mineralocorticoid receptor antagonists decrease the aldosterone effect by binding to the mineralocorticoid receptor inhibiting aldosterone. This leads to higher levels of potassium in serum and increased sodium excretion, resulting in decreased body fluid and lower blood pressure.
== Historical fiction author == Wilson said of his accomplishments outside of ophthalmology, that writing fiction is a “great pleasure” and a treasured hobby. His first novel, Winter in Kandahar, was a 2004 finalist for the Benjamin Franklin Award for Best New Voice in Fiction. A second novel, Ascent from Darkness, was a finalist in the Action/Adventure category (2008) in the Indie Book Awards. Wilson's third novel, The Ghosts of Anatolia, received multiple awards in 2010 and 2011. A more recent novel, The Benghazi Affair was the Benjamin Franklin Award Audio Book Gold Prize winner in fiction.
== Awards == Awards for his work include the Award of Society of Polymer Science, Japan (1982), The Chemical Society of Japan Award for 1999, Chirality Medal (2001), Medal with Purple Ribbon (Japanese Government) (2002), Fujiwara Prize (2005), and the Japan Prize (2019). In 2020, he became a laureate of the Asian Scientist 100 by the Asian Scientist.
Sources: en.wikipedia.org
Specialty plastics are materials with unique characteristics, such as ultra-high strength, electrical conductivity, electro-fluorescence, high thermal stability, etc. The dividing lines between the various types of plastics is not based on material but rather on their properties and applications. For example, polyethylene (PE) is a cheap, low friction polymer commonly used to make disposable bags for shopping and trash, and is considered a commodity plastic, whereas medium-density polyethylene (MDPE) is used for underground gas and water pipes, and another variety called ultra-high-molecular-weight polyethylene (UHMWPE) is an engineering plastic which is used extensively as the glide rails for industrial equipment and the low-friction socket in implanted hip joints.
Tumor growth (see HP59) Revascularization or neovascularization after trauma, for example, after cardiac ischemia or retinal ischemia Endometriosis - It appears that up to 37% of the microvascular endothelium of the ectopic endometrial tissue originates from endothelial progenitor cells.
False negative results for antibody testing can occur in people who are immunosuppressed, as they produce lower amounts of antibodies, and in people who receive antimicrobial drugs early in the course of the infection.
Sources: en.wikipedia.org
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.
Intranasal delivery is the route described in most published work. It is used because the peptide is degraded quickly once it reaches circulation. Direct evidence of brain penetration in humans is lacking.
Most trials are small, regionally concentrated, and often lack rigorous blinding or placebo control. Independent replication is limited. Reviews in English generally rate the evidence as preliminary.
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.