This is a working overview of mass spectrometry, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-11-13. Anything still debated is marked as such rather than presented as settled.
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.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid form |
| Solubility class | Freely soluble in water | Hydrophilic heptapeptide |
| Dry storage temperature | -20 degrees Celsius or lower | Sealed, desiccated, protected from light |
| Solution storage | 2 to 8 degrees Celsius short term | Avoid repeated freeze-thaw cycles |
| Common identification method | Reversed-phase HPLC with mass spectrometry | Confirms purity and molecular mass |
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.
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.
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. 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.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
== Mechanism of action == Lebrikizumab blocks interleukin 13 (IL-13), a cytokine (cell-signalling protein) that is produced by a type of white blood cell called Th2 cells. IL-13 is thought to induce the expression of another signalling protein, periostin, by epithelial cells of the bronchi. Periostin in turn seems to partake in a number of asthma related problems, such as bronchial hyperresponsiveness, inflammation, and activation and proliferation of airway fibroblasts, which are involved in airway remodelling. This theory is supported by the fact that people with high periostin levels responded significantly better to lebrikizumab in the phase II study: the forced expiratory volume in 1 second (FEV1) was 8.2% higher than under placebo in this group (measured from the respective baselines), while low-periostin participants had 1.6% higher FEV1, and the average value for all participants was 5.5%. The FEV1 increase in low-periostin participants was not statistically significant.
The breast implant has no clinical bearing upon lumpectomy breast-conservation surgery for women who developed breast cancer after the implantation procedure, nor does the breast implant interfere with external beam radiation treatments (XRT); moreover, the post-treatment incidence of breast-tissue fibrosis is common, and thus a consequent increased rate of capsular contracture. There is tentative evidence that women who have had breast augmentation, have worse breast cancer prognosis. The use of implants for breast reconstruction after breast cancer mastectomy appears to have no negative effect upon cancer-related death. There have been multiple reported cases of other adverse effects of mammography of women with breast implants; ruptures resulting from pressure exerted on the breast implant make up a majority of these cases. Compression may also lead to pain or exacerbate already existing pain in the breasts.
John Herbert resigned from Parliament on 13 September 1978 due to terminally ill health. Sam Doumany was appointed to replace him in the cabinet and as Minister for Welfare on 2 October 1978. On 9 October 1978, Llew Edwards replaced William Knox as leader of the Liberal Party and hence Deputy Premier of Queensland. On 15 December 1978, they swapped portfolios, with Knox becoming Minister for Health and Edwards becoming Treasurer. On 31 July 1979, Max Hodges resigned from Parliament, and on 21 August 1978, Tom Newbery resigned from the ministry. Max Hooper and Ivan Gibbs were appointed to replace them in cabinet and in their roles on 24 August 1978. On 17 August 1980, Ron Camm resigned from Parliament to become chairman of the Sugar Board. Russ Hinze and Vic Sullivan added his cabinet roles to their responsibilities, while Mike Ahern was appointed to the cabinet vacancy.
Sources: en.wikipedia.org
=== 10 June === The SAF accused the LNA of carrying out a joint attack with the RSF in the Libya-Egypt-Sudan border triangle. Eight people were killed in an SAF drone attack on a school sheltering IDPs in Abu Zabad, West Kordofan.
== Properties of alginate dressings == The gelling properties of alginates are attributed to the presence of calcium ions that help form a slow degradeable cross-linked polymer gel. Once in contact with an exuding wound, an ion-exchange reaction takes place between the calcium ions in the dressing and sodium ions in serum or wound fluid. When a significant proportion of the calcium ions on the fibre have been replaced by sodium, the fibre swells and partially dissolves forming a gel-like mass. The gel formed is highly hydrophilic, which limits wound secretions and minimizes bacterial contamination. The hydrophilic gel is formed from the initial contact between the sodium ions in wound exudate and calcium ions in alginate. As the gel forms it conforms to the shape of the wound. This is why alginate dressings are good for irregular shaped and wounds that have deep cavities.
A purported reason was the appearance of high potency cannabis. They believe skunk accounts for between 70% and 80% of samples seized by police (despite the fact that skunk can sometimes be incorrectly mistaken for all types of herbal cannabis). Extracts such as hashish and hash oil typically contain more THC than high potency cannabis infructescences.
Sources: en.wikipedia.org
KDEL receptors initiate the mechanism by which proteins are transported from the Golgi to the ER. These proteins were originally from the ER and they escaped into the cis-Golgi. The KDEL signal sequence is recognized by KDEL receptors, which are commonly located in the cis-Golgi, lysosomes, and secretory vesicles. These receptors are recycled during each transport cycle. KDEL receptor binding is dependent on pH, in which the ligand (target protein) binds strongly to the receptor in the cis-Golgi due to the unique low pH (6, in in vitro experiments pH 5 shows strongest binding) characteristic of the biochemical environment of the cis-Golgi network. As the vesicle that contains the KDEL receptor reaches the ER, the receptor is inactive due to the high pH (7.2-7.4) of the ER, resulting in the release of the target protein/ligand. A study conducted by Becker et al. demonstrated through experimentation and simulation that KDEL receptors/cargo clustering at the cell surface is caused by the transport of cargo-synchronized receptors from and to the plasma membrane. The video on the right demonstrates an experiment conducted by Becker et al. demonstrating the dynamics of the KDEL receptor clustering's time dependence with a full experiment from start to finish (60 minutes). Within the paper, the authors note the importance of understanding the mechanism of action of the receptor clustering and dynamic reorganization because of its potential understanding to use for designing targeted therapeutics.
2 CH3CH=CH2 + 3 O2 + 2 NH3 → 2 N≡CCH=CH2 + 6 H2O In the production of acrylonitrile, a side product is acetonitrile. On an industrial scale, several derivatives of benzonitrile, phthalonitrile, as well as Isobutyronitrile are prepared by ammoxidation. The process is catalysed by metal oxides and is assumed to proceed via the imine. Ammoxidation is a heterogeneously catalyzed gas-phase reaction in which aliphatic or methyl-substituted aromatic compounds react with oxygen (air) and ammonia to form nitriles, with water as a by-product. Reaction temperatures exceed 300 °C, and oxides of vanadium, chromium, or molybdenum serve as catalysts. Acrylonitrile, an important precursor for polymer production (see Use section), is primarily manufactured by ammoxidation of propene. The principal industrial route to hydrogen cyanide is the Andrussov process, i.e., ammoxidation of methane over a platinum catalyst. However, a significant proportion of global hydrogen cyanide production arises as a by-product of acrylonitrile manufacture.
The amount of YAN that winemakers will see in their grape musts depends on a number of components including grape variety, rootstock, vineyard soils and viticultural practices (such as the use of fertilizers and canopy management) as well as the climate conditions of particular vintages.
The Gaddafi–Abdullah feud came into public view again in the 2009 Arab League summit when Gaddafi accused Abdullah, who had become King of Saudi Arabia in 2005, of being created by Britain and protected by the US. Alluding to their 2003 altercation, Gaddafi taunted Abdullah for ostensibly avoiding a confrontation with him for six years and quoted Abdullah's 2003 "grave awaits you" threat back at him before storming out of the meeting to visit a museum. Abdullah also left the meeting hall in anger. A Saudi official later claimed that Gaddafi and Abdullah had held a 30 minutes meeting at the sideline of the summit and that the "personal problem" between them was "over". However, Gaddafi had given weapons and money to the Houthis to attack Saudi Arabia.
Sources: en.wikipedia.org
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.
Reversed-phase HPLC establishes purity, while mass spectrometry confirms the expected molecular mass. Sequence confirmation may use tandem mass spectrometry or peptide mapping. A certificate of analysis typically reports these results alongside the analytical method applied.
In Russia it is a registered medicine available by prescription. In many other countries it is not approved for human use and is supplied only as a research chemical. Import and possession rules differ by jurisdiction, and buyers are responsible for checking local requirements.
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.