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 2025-10-31. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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 |
|---|---|---|
| Common route | Intranasal | Also injected in some animal work |
| Solubility class | Freely soluble in water | Solid form is hygroscopic |
| Typical storage | About -20 degrees Celsius | Keep desiccated and dark |
| Purity method | Reverse-phase HPLC | Reported as area percent |
| Confirmatory method | Mass spectrometry | Verifies expected molecular mass |
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
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.
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.
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.
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.
== Description == The tree grows up to 25 meters in height. The bark is gray with fissures. Leaf blade is obovate elliptic with light green midrib and dense black dots at under surface. Leaf apex has a clear mucronate spike and leaf stalk is 2–3 cm long. Inflorescence is branched 1-2 times with 2-4 buds borne on short peduncle. Petals are white and slightly hairy with style 2–3 mm long.
Under these conditions, if the pathogenic mutation arises after a compensatory mutation, then P can become fixed in the population. The second model of CPDs states that P and C are both deleterious mutations resulting in fitness valleys when mutations occur simultaneously. Using publicly available, Ferrer-Costa et al. 2007 obtained compensatory mutations and human pathogenic mutation datasets that were characterized to determine what causes CPDs. Results indicate that the structural constraints and the location in protein structure determine whether compensated mutations will occur.
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Diseases of the endocrine system are common, including conditions such as diabetes mellitus, thyroid disease, and obesity. Endocrine disease is characterized by misregulated hormone release (a productive pituitary adenoma), inappropriate response to signaling (hypothyroidism), lack of a gland (diabetes mellitus type 1, diminished erythropoiesis in chronic kidney failure), or structural enlargement in a critical site such as the thyroid (toxic multinodular goitre). Hypofunction of endocrine glands can occur as a result of loss of reserve, hyposecretion, agenesis, atrophy, or active destruction. Hyperfunction can occur as a result of hypersecretion, loss of suppression, hyperplastic or neoplastic change, or hyperstimulation. Endocrinopathies are classified as primary, secondary, or tertiary. Primary endocrine disease inhibits the action of downstream glands. Secondary endocrine disease is indicative of a problem with the pituitary gland. Tertiary endocrine disease is associated with dysfunction of the hypothalamus and its releasing hormones. As the thyroid, and hormones have been implicated in signaling distant tissues to proliferate, for example, the estrogen receptor has been shown to be involved in certain breast cancers. Endocrine, paracrine, and autocrine signaling have all been implicated in proliferation, one of the required steps of oncogenesis. Other common diseases that result from endocrine dysfunction include Addison's disease, Cushing's disease and Graves' disease.
==== Acetaminophen ==== One of the main types of drug studies conducted is using astronauts as test subjects and measuring drug dynamics before and after spacecraft flight. A study on acetaminophen pharmacokinetics was performed on ten astronauts, studying its concentration dynamics in saliva two months before spaceflight and during long-term spaceflight. Saliva samples were analyzed at intervals of 0.017, 0.33, 0.5, 0.75, 1, 2, 4, and 6 hours after acetaminophen intake by HPLC with UV spectrophotometric detection at 254 nm. The absorption of acetaminophen during spaceflight was delayed after tablet administration and the bioavailability of the encapsulated drug was found to be moderately decreased. Additionally, the half-life of encapsulated acetaminophen was prolonged during spaceflight.
Sources: en.wikipedia.org
== See also == Resonance-enhanced multiphoton ionization Rydberg ionization spectroscopy Photoionization Atmospheric-pressure laser ionization Radiometric dating Electron excitation Tunable lasers Cosmochemistry
== Prognosis == Prognosis depends greatly on the nature and severity of the condition. Some deficiencies cause early mortality (before age one), others, with or even without treatment, are lifelong conditions that cause little mortality or morbidity. Newer stem cell transplant technologies may lead to gene-based treatments of debilitating and fatal genetic immune deficiencies. The prognosis of acquired immune deficiencies depends on avoiding or treating the causative agent or condition (like AIDS).
Some gas panels have a separate supply gauge for each diver downstream of the supply valve, but this is not standard practice. The gas panel may be fairly large and mounted on a board for convenience of use, or may be compact and mounted inside a portable box, for ease of transport. Gas panels are usually for one, two or three divers. In some countries, or under some codes of practice, the surface standby diver must be supplied from a separate panel to the working diver/s. A wet or closed bell will be fitted with a bell gas panel to supply gas to the divers' excursion umbilicals. The bell gas panel is supplied with primary gas from the surface via a bell umbilical, and on-board emergency gas from high-pressure storage cylinders mounted on the frame of the bell.
=== Biological strategies === It has become possible to accelerate natural aerobic, anaerobic, and sequential aerobic and/or anaerobic biological processes to minimize the presence of NAPLs in the subsurface environment. Most bioremediation strategies rely on the presence of specific populations of bacteria/microorganisms and the addition of organic carbon to stimulate biodegradation. This organic carbon can be supplied via injection of soluble organic carbon sources such as lactate, alcohols, cheese whey, etc. and placement of slow-release electron donors such as vegetable oil and soybean oil emulsions. Sufficient dissolved oxygen must be present for aerobic biodegradation, which can be supplied through strategies including air sparging and SVE. That said, the ability to supply sufficient oxygen is a limiting factor affecting the success of this type of remediation strategy. Also, many cases require the presence of inducers such as methane, propane, ammonia, or toluene, which are contaminants in and of themselves that are inherently harmful to the subsurface environment. Yet another challenge is maintaining a sufficient population of bacteria/microorganisms in the face of competition from native bacteria and other external pressures. There is also regulatory pushback to the use of genetically modified bacteria. Furthermore, NAPLs may not be readily bioavailable, limiting the effectiveness of biodegradation strategies. In this sense, biodegradation may not be appropriate as a single solution, but it can certainly be used in conjunction with other strategies.
== Bodybuilding titles == 1984 Mr Birmingham Novice, 1st 1985 World Games, 7th Heavyweights 1986 British Championships, 1st Heavyweight 1988 British Championships, 1st Heavyweight and overall 1990 Night of Champions, 2nd 1991 Night of Champions, 1st 1991 Mr. Olympia, 2nd 1991 English Grand Prix, 1st 1992 Mr. Olympia, 1st 1992 English Grand Prix, 1st 1993 Mr. Olympia, 1st 1994 Mr. Olympia, 1st 1994 Mr. Worldwide, 1st 1994 Spanish Grand Prix, 1st 1994 German Grand Prix, 1st 1994 English Grand Prix, 1st 1995 Mr. Olympia, 1st 1996 Mr. Olympia, 1st 1996 Spanish Grand Prix, 1st 1996 German Grand Prix, 1st 1996 English Grand Prix, 1st 1997 Mr. Olympia, 1st
Sources: en.wikipedia.org
Hydroxypethidine (Bemidone) is an opioid analgesic that is an analogue of the more commonly used pethidine (meperidine). Hydroxypethidine is slightly more potent than meperidine as an analgesic, 1.5x meperidine in potency, and it also has NMDA antagonist properties like its close relative ketobemidone. Hydroxypethidine has similar effects to other opioids, and produces analgesia, sedation and euphoria. Side effects can include itching, nausea and potentially serious respiratory depression which can be life-threatening. Hydroxypethidine is under international control under the Single Convention on Narcotic Drugs 1961 and therefore controlled like morphine in most countries; in the United States it is a Schedule I Narcotic controlled substance with an ACSCN of 9627 and a 2014 annual aggregate manufacturing quota of 2 grams. The salt in use is the hydrochloride, with a free base conversion ratio of 0.878.
== Epidemiology == The annual incidence is about 1.1 per 100,000 annually in population studies from the United States and France. From 1994 to 2003, the incidence increased threefold; this has been attributed to the more widespread use of modern imaging modalities rather than a true increase. Similarly, those living in urban areas are more likely to receive appropriate investigations, accounting for increased rates of diagnosis in those dwelling in cities. It is suspected that a proportion of cases in people with mild symptoms remains undiagnosed. There is controversy as to whether VAD is more common in men or in women; an aggregate of all studies shows that it is slightly higher incidence in men (56% versus 44%). Men are on average 37–44 years old at diagnosis, and women 34–44. While dissection of the carotid and vertebral arteries accounts for only 2% of strokes (which are usually caused by high blood pressure and other risk factors, and tend to occur in the elderly), they cause 10–25% of strokes in young and middle-aged people. Dissecting aneurysms of the vertebral artery constitute 4% of all cerebral aneurysms, and are hence a relatively rare but important cause of subarachnoid hemorrhage.
Joseph Swan (1828–1914) was a British physicist and chemist. In 1850, he began working with carbonized paper filaments in an evacuated glass bulb. By 1860, he was able to demonstrate a working device but the lack of a good vacuum and an adequate supply of electricity resulted in a short lifetime for the bulb and an inefficient source of light. By the mid-1870s better pumps had become available, and Swan returned to his experiments.
=== Unnatural amino acid incorporation === Cell-free systems have also been used to incorporate unnatural amino acids. Shimizu et al. were able to change a stop codon to a sense codon by omitting the RF1 release factor, indicating ability to insert desired amino acids in unnatural situations. This is of use in systems where working inside a cell is problematic, such as the process of amino acid metabolism preventing specific labelling of amino acids that would be useful in multidimensional NMR spectroscopy. Kigawa et al.were able to successfully label amino acids in a cell-free system where amino acid metabolism was no longer present, thus making such systems useful to NMR studies.
At constant temperature, the rate of carbon assimilation varies with irradiance, increasing as the irradiance increases, but reaching a plateau at higher irradiance. At low irradiance, increasing the temperature has little influence on the rate of carbon assimilation. At constant high irradiance, the rate of carbon assimilation increases as the temperature is increased. These two experiments illustrate several important points: First, it is known that, in general, photochemical reactions are not affected by temperature. However, these experiments clearly show that temperature affects the rate of carbon assimilation, so there must be two sets of reactions in the full process of carbon assimilation. These are the light-dependent 'photochemical' temperature-independent stage, and the light-independent, temperature-dependent stage. Second, Blackman's experiments illustrate the concept of limiting factors. Another limiting factor is the wavelength of light. Cyanobacteria, which reside several meters underwater, cannot receive the correct wavelengths required to cause photoinduced charge separation in conventional photosynthetic pigments. To combat this problem, Cyanobacteria have a light-harvesting complex called Phycobilisome. This complex is made up of a series of proteins with different pigments which surround the reaction center.
Sources: en.wikipedia.org
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.
Reported human trials are few, brief and originate mainly from one country. They describe effects on anxiety-related measures, but sample sizes are small and reporting is limited. The results are widely regarded as preliminary rather than confirmed.
Reverse-phase liquid chromatography is used to assess purity and separation of related impurities. Mass spectrometry confirms that the observed molecular mass matches the expected peptide. A certificate of analysis from the supplier is the usual document of record.
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.