A practical reference on mass spectrometry: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-10-08 and is reviewed periodically as new material appears.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Principal proposed target | GABA-A receptor complex | Hypothesis derived mainly from animal pharmacology |
| Common behavioral assay | Elevated plus maze | Rodent test for anxiety-like behavior |
| Reported molecular marker | Hippocampal BDNF expression | Measured by immunoassay or mRNA quantification |
| Typical dosing route | Intranasal | Chosen to reduce first-pass metabolism |
| Reported plasma half-life | Minutes | Based on limited peptide stability data |
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.
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.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
=== By instrument === A cut by a knife or a scalpel generally scars, though a piercing by a needle does not. In 1976, a 3 by 3 cm scar on a non-diabetic was regenerated by insulin injections and the researchers, highlighting earlier research, argued that the insulin was regenerating the tissue. The anecdotal evidence also highlighted that a syringe was one of two variables that helped bring regeneration of the arm scar. The syringe was injected into the four quadrants three times a day for eighty-two days. After eighty-two days, after many consecutive injections, the scar was resolved and it was noted no scar was observable by the human eye. After seven months the area was checked again and it was once again noted that no scar could be seen. In 1997, it was proven that wounds created with an instrument that are under 2mm can heal scar free, but larger wounds that are larger than 2mm healed with a scar. In 2013, it was proven in pig tissue that full thickness micro columns of tissue, less than 0.5mm in diameter could be removed and that the replacement tissue, was regenerative tissue, not scar. The tissue was removed in a fractional pattern, with over 40% of a square area removed; and all of the fractional full thickness holes in the square area healed without scarring. In 2016 this fractional pattern technique was also proven in human tissue. In 2021, more people were paying attention to the possibility of scar free healing alongside new technologies involving instruments.
== Research == A 2015 trial found nicotinamide to reduce the rate of new nonmelanoma skin cancers and actinic keratoses in a group of people at high risk for the conditions. Nicotinamide has been investigated for many additional disorders, including treatment of bullous pemphigoid and nonmelanoma skin cancers. Nicotinamide may be beneficial in treating psoriasis. There is tentative evidence for a potential role of nicotinamide in treating acne, rosacea, autoimmune blistering disorders, ageing skin, and atopic dermatitis. Nicotinamide also inhibits poly(ADP-ribose) polymerases (PARP-1), enzymes involved in the rejoining of DNA strand breaks induced by radiation or chemotherapy. ARCON (accelerated radiotherapy plus carbogen inhalation and nicotinamide) has been studied in cancer. Research has suggested nicotinamide may play a role in the treatment of HIV.
=== Positions on trans identity, accusations of transphobia and connections to the far-right === On January 22, 2020, after a collage was posted in the city of Montpellier calling for the inclusion of trans women in the feminist movement with the slogan "sisters not cisTERF" (a pun on "cis", i.e. not trans, and "TERF", meaning "transgender-exclusionary radical feminist"), she commented she felt trans activism had become too important in the collage movement and within feminism on Twitter. She stated in particular that being a woman is a question of biology and that the activism of trans women was insulting and reduced women to a set of patriarchal stereotypes such as makeup and clothes. She denied trans women's womanhood, stating: "Throughout time, men have tried to silence women by silencing their revolts. Today, they do it from the inside by infiltrating our struggles". She refuses trans-inclusive language such as "people with vulvas". Her positions have led to her being considered a "TERF" by intersectional feminists. Following these statements, the Instagram account Collages Féminicides Paris distanced itself from her comments: "Discrimination has always been condemned […]. We're talking about the exclusion of a part of women from the struggle; transphobia is not a debate." She became increasingly marginalized in the collage movement, months after leaving its leadership. She was the subject of numerous insults on social networks, so much so that the collective reacted and specified that it repudiates any "killing rhetoric".
Parental care came about independently in: mammals, most birds, some insects, some fish and crocodilians. Regeneration, many different unrelated species can grow new limbs, tail or other body parts, if body parts are lost. The statocyst is a balance sensory receptor independently found in different organisms like: some aquatic invertebrates, including bivalves, cnidarians, echinoderms, cephalopods, and crustaceans. Also found in single-cell ciliate. A similar structure is also found in Xenoturbella. Hearing came about in many different unrelated species with the: tympanal organ, Johnston's organ and mammal/bird ears. Also the simpler hearing found in reptiles, with only the stapes bone. Pincushion-form starfish have evolved at least four times. Infrared vision is in many different unrelated species: pit viper snakes (rattlesnakes), pythons, vampire bats, and wood-boring wasps and fire beetles.
==== Fidelity ==== Unlike the proofreading mechanisms of DNA polymerase those of RNAP have only recently been investigated. Proofreading begins with separation of the mis-incorporated nucleotide from the DNA template. This pauses transcription. The polymerase then backtracks by one position and cleaves the dinucleotide that contains the mismatched nucleotide. In the RNA polymerase this occurs at the same active site used for polymerization and is therefore markedly different from the DNA polymerase where proofreading occurs at a distinct nuclease active site. The overall error rate is around 10−4 to 10−6.
Sources: en.wikipedia.org
The muscular layer consists of two layers of muscle, the inner and outer layer. The muscle of the inner layer is arranged in circular rings around the tract, whereas the muscle of the outer layer is arranged longitudinally. The stomach has an extra layer, an inner oblique muscular layer. Between the two muscle layers is the myenteric plexus (Auerbach's plexus). This controls peristalsis. Activity is initiated by the pacemaker cells (interstitial cells of Cajal). The gut has intrinsic peristaltic activity (basal electrical rhythm) due to its self-contained enteric nervous system. The rate can, of course, be modulated by the rest of the autonomic nervous system. The layers are not truly longitudinal or circular, rather the layers of muscle are helical with different pitches. The inner circular is helical with a steep pitch and the outer longitudinal is helical with a much shallower pitch. The coordinated contractions of these layers is called peristalsis and propels the food through the tract. Food in the GI tract is called a bolus (ball of food) from the mouth down to the stomach. After the stomach, the food is partially digested and semi-liquid, and is referred to as chyme. In the large intestine the remaining semi-solid substance is referred to as faeces. The circular muscle layer prevents food from travelling backward and the longitudinal layer shortens the tract. The thickness of the muscular layer varies in each part of the tract:
=== Heart failure === Microarray analysis from one report shows a significant decrease in myocardial arginine:glycine amidinotransferase (AGAT) gene expression during the late-stage heart failure. This suggests that the reduced AGAT may correlate with loss of heart function. Increase of AGAT expression in the myocardium after heart failure due to increase in creatine synthesis was associated with favorable outcome.
=== Central Powers === Despite Balfour's warning to the War Cabinet that Germany was aiming to court Zionist support, German authorities were balancing the interests of their Zionist and non-Zionist Jewish communities (the latter represented by the Hilfsverein der Juden in Deutschland) and refrained from showing favoritism to one side or the other. They successfully urged the Ottomans to show lenience towards Zionists but were not attempting anything like an equivalent to the Balfour Declaration. The publication of the Balfour Declaration was thus met with tactical responses from the Central Powers. The participation of the Ottoman Empire in the alliance meant that Germany was unable to effectively counter the British pronouncement. Some within the German government viewed potential Zionist support for Britain's war effort as a substantial loss for their side. Two weeks following the declaration, Ottokar Czernin, the Austrian Foreign Minister, gave an interview to Arthur Hantke, President of the Zionist Federation of Germany, promising that his government would influence the Turks once the war was over.
Since then, sulfur has typically been produced from petroleum, natural gas, and related fossil resources, from which it is obtained mainly as hydrogen sulfide. Organosulfur compounds, undesirable impurities in petroleum, may be upgraded by subjecting them to hydrodesulfurization, which cleaves the C–S bonds:
Sources: en.wikipedia.org
=== Stable isotopes === The first evidence for multiple isotopes of a stable (non-radioactive) element was found by J. J. Thomson in 1912/1913 as part of his exploration into the composition of canal rays (positive ions). Thomson channelled streams of ions through parallel magnetic and electric fields, measured their deflection by placing a photographic plate in their path, and computed their mass to charge ratio using a method that became known as the Thomson's parabola method. Each 'line' could be identified with a specific atomic weight, and therefore different elements and compounds could be identified. Thomson's initial paper in the Philosophical Magazine explains the technique used, but makes no comment on anomalous lines; however, in a talk given to the Royal Institution on 17 January 1913 Thomson identified "a line corresponding to an atomic weight 22, which can not be identified with the line due to any known gas". He went on to comment thatThe origin of this line presents many points of interest; there are no known gaseous compounds of any of the recognized elements which have this molecular weight. Again, if we accept Mendeleef's Periodic Law, there is no room for a new element with this atomic weight.The same lecture was then given to the Cambridge Philosophical Society on 27 January 1913, and later in the year Thomson presented his mature interpretation as the Royal Society's Bakerian Lecture.
The mean improvement in scores with dextromethorphan/bupropion was statistically significant but not clinically significant relative to placebo at all assessed timepoints including at the end of week 1, although at the end of the study some patients did have clinically significant improvement. In Study 2 (STRIDE-1), dextromethorphan/bupropion was compared with bupropion alone in another randomized controlled trial. The dose of bupropion in the study was lower than the target dose recommended for clinical practice. In this study, dextromethorphan/bupropion showed significantly greater improvement than bupropion alone in the first two weeks of treatment but not by week 6 of treatment in people with major depressive disorder. The baseline scores were 33.4 points with dextromethorphan/placebo and 33.2 points with placebo, while the score reductions at week 1 were 5.2 points on the MADRS with dextromethorphan/bupropion and 3.6 points with bupropion (a 1.6-point difference), at week 2 were 8.0 points with dextromethorphan/bupropion and 6.1 points with bupropion (a 1.9-point difference), and at week 6 were 11.6 points with dextromethorphan/bupropion and 9.4 points with bupropion (a 2.2-point difference). On the basis of this trial, the FDA concluded that dextromethorphan contributes to the apparent antidepressant effects of dextromethorphan/bupropion.
A field ration (known under a variety of other names) is a military ration intended to provide nutrition and sustenance in the field, in combat, at the front line, or where eating facilities are otherwise unavailable. Field rations can be categorized into two main types:
Sources: en.wikipedia.org
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.
Behavioral endpoints include time spent in open arms of the elevated plus maze and avoidance latencies. Biochemical endpoints include BDNF concentration, cytokine levels, and monoamine metabolite ratios in brain tissue.
Most published studies are small, originate from a limited number of laboratories, and lack independent replication. Dose-response relationships, measured brain exposure, and long-term outcomes are not well characterized.
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.