peptidase comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2025-11-17. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
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.
| 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 |
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
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.
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.
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.
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.
Others who performed specialist functions were the controller of army accounts, the Army Medical Board, the Commissariat Department, the Board of General Officers, the Judge Advocate General of the Armed Forces, the Commissary General of Muster, the Paymaster General of the forces, and (particularly with regard to the Militia) the Home Office. The term War Department was initially used for the separate office of the Secretary of State for War; in 1855, the offices of Secretary at War and Secretary of State for War were merged, and thereafter the terms War Office and War Department were used somewhat interchangeably.
=== Autism === James is best known for her autism-related research. Regarding autism, James' view is that the transsulfuration pathway is disrupted in autistic children, resulting in these children being deficient in glutathione, as well as vitamins such as vitamin B6 and vitamin B12, and that maternal glutathione deficiency may also be a risk factor for autism. She has also claimed that administering these compounds as supplements, as well as methylcobalamin and folinic acid, to autistic children can significantly restore their levels of glutathione and cysteine and may therefore be useful in the treatment of autism. In addition, she has speculated that autistic children possess an impaired methylation capacity and that, according to a study she presented at the 2005 Experimental Biology conference, they have a unique biological "fingerprint" in their blood which neurotypical children lack. With regard to this particular study, James said, "One interpretation of this finding is that children with autism would be less able to detoxify and eliminate these heavy metals." According to the official blog of Autism Speaks, James found that autistic children exhibit abnormal folate metabolism that is detectable by higher levels of plasma homocysteine, adenosine, and S-adenosyl-L-homocysteine in the mothers of these children. Her glutathione-related research has been cited by anti-vaccine activists, such as Robert F.
Molecular dimers are often formed by the reaction of two identical compounds e.g.: 2A → A−A. In this example, monomer "A" is said to dimerize to give the dimer "A−A". Dicyclopentadiene is an asymmetrical dimer of two cyclopentadiene molecules that have reacted in a Diels-Alder reaction to give the product. Upon heating, it "cracks" (undergoes a retro-Diels-Alder reaction) to give identical monomers:
=== Patent disputes === The PCR technique was patented by Kary Mullis and assigned to Cetus Corporation, where Mullis worked when he invented the technique in 1983. The Taq polymerase enzyme was also covered by patents. There have been several lawsuits related to the technique brought by DuPont. The Swiss pharmaceutical company Hoffmann-La Roche purchased the rights to the patents in 1992. The last of the commercial PCR patents expired in 2017. A related patent battle over the Taq polymerase enzyme is still ongoing in several jurisdictions around the world between Roche and Promega. The legal arguments have extended beyond the lives of the original PCR and Taq polymerase patents, which expired on 28 March 2005.
Sources: en.wikipedia.org
== Quarks and the mass of a proton == In quantum chromodynamics, the modern theory of the nuclear force, most of the mass of protons and neutrons is explained by special relativity. The mass of a proton is about 80–100 times greater than the sum of the rest masses of its three valence quarks, while the gluons have zero rest mass. The extra energy of the quarks and gluons in a proton, as compared to the rest energy of the quarks alone in the QCD vacuum, accounts for almost 99% of the proton's mass. The rest mass of a proton is, thus, the invariant mass of the system of moving quarks and gluons that make up the particle, and, in such systems, even the energy of massless particles confined to a system is still measured as part of the rest mass of the system. Two terms are used in referring to the mass of the quarks that make up protons: current quark mass refers to the mass of a quark by itself, while constituent quark mass refers to the current quark mass plus the mass of the gluon particle field surrounding the quark. These masses typically have very different values. The kinetic energy of the quarks that is a consequence of confinement is a contribution (see Mass in special relativity). Using lattice QCD calculations, the contributions to the mass of the proton are the quark condensate (~9%, comprising the up and down quarks and a sea of virtual strange quarks), the quark kinetic energy (~32%), the gluon kinetic energy (~37%), and the anomalous gluonic contribution (~23%, comprising contributions from condensates of all quark flavors).
Rieske proteins are iron–sulfur protein (ISP) components of cytochrome bc1 complexes and cytochrome b6f complexes and are responsible for electron transfer in some biological systems. John S. Rieske and co-workers first discovered the protein and in 1964 isolated an acetylated form of the bovine mitochondrial protein. In 1979, Trumpower's team isolated the "oxidation factor" from bovine mitochondria and showed it was a reconstitutively-active form of the Rieske iron-sulfur protein. It is a unique [2Fe-2S] cluster in that one of the two Fe atoms is coordinated by two histidine residues rather than two cysteine residues. They have since been found in plants, animals, and bacteria with widely ranging electron reduction potentials from -150 to +400 mV.
Malignancies can develop in the glabrous and hair-bearing parts of the vulva. Based on the cellular origin and histology, vulvar cancers are classified into squamous cell carcinomas, melanomas, basal cell carcinomas, adenocarcinomas, sarcomas and invasive extramammary Paget's disease. Squamous cell carcinomas represent the most common variant of vulvar cancers and account for approximately 75%. These are usually found in the labia, particularly the labia majora. The second most common vulvar cancer is basal cell carcinoma, which rarely spreads to regional lymph nodes or distant organs. The third most common subtype is vulvar melanoma. Studies have shown that vulvar melanomas appear to have a different tumor biology and mutational characteristics compared to skin melanomas, which has a direct impact on the medical treatment of vulvar melanomas. Signs and symptoms of vulvar cancer can include: itching, or bleeding; skin changes including rashes, sores, lumps or ulcers, and changes in vulvar skin coloration. Pelvic pain might also occur especially during urinating and sex. However, a significant proportion remains asymptomatic in early disease stages, often delaying its diagnosis. As such, 32% of women with vulvar melanoma already have regional involvement or distant metastases at the time of diagnosis, which significantly impacts prognosis. Surgery (with or without removal of regional lymph nodes) is usually the primary treatment modality.
The Vermont Army National Guard and Vermont Air National Guard are collectively known as the Vermont National Guard or "Green Mountain Boys". Both units use the original Green Mountain Boys battle flag as their banner.
Silence was their way of maintaining control in these situations, but it often came at the expense of their health and the advancement of female health and medicine. This silence and control were most obviously seen when the health problem was related to the core of Ming fuke, or the sexual body. It was often in these diagnostic settings that women would choose silence. In addition, there would be a conflict between patient and doctor on the probability of her diagnosis. For example, a woman who thought herself to be past the point of child-bearing age, might not believe a doctor who diagnoses her as pregnant. This only resulted in more conflict.
Sources: en.wikipedia.org
According to Kardashev, the transmissions of an extraterrestrial civilization (what SERENDIP is looking for) can be divided into two types. On the one hand, there can be an exchange of information between highly developed civilizations or civilizations at similar stages of evolution. On the other hand, the transmission of information can be aimed at raising the level of other less developed civilizations. If supercivilizations do exist, the transmissions of the first type must remain inaccessible to our observation because they must be unidirectional and not be directed toward the Solar System. Conversely, those of the second type must be easily detectable by our listening devices. A signal of artificial origin should contain more than 10 and less than 100 bits. The latter would be of two types: transient and stable. Several criteria allow us to distinguish a signal of artificial origin from others. First, the optimal region of the spectrum to host artificial signals is the one where the temperature of the cosmic microwave background is the lowest. Second, artificial sources must have a minimum angular size. The presence of suspicious data in other regions of the spectrum (such as circular polarization, radio and optical frequencies, or X-ray emissions) can confirm that it is an intelligent transmission. Two sources among those studied have parameters close to those expected: 1934-63 and 3C 273B. For L. M.
Similar to the frozen section procedure employed in medicine, cryosectioning is a method to rapidly freeze, cut, and mount sections of tissue for histology. The tissue is usually sectioned on a cryostat or freezing microtome. The frozen sections are mounted on a glass slide and may be stained to enhance the contrast between different tissues. Unfixed frozen sections can be used for studies requiring enzyme localization in tissues and cells. Tissue fixation is required for certain procedures such as antibody-linked immunofluorescence staining. Frozen sections are often prepared during surgical removal of tumors to allow rapid identification of tumor margins, as in Mohs surgery, or determination of tumor malignancy, when a tumor is discovered incidentally during surgery.
Brinkley initiated a boom in male impotence treatments in the U.S. in the 1920s and 1930s, with radio programs that recommended expensive goat gland implants and "mercurochrome" injections as the path to restored male virility, including operations by surgeon Serge Voronoff. Modern drug therapy for ED made a significant advance in 1983, when British physiologist Giles Brindley dropped his trousers and demonstrated to a shocked Urodynamics Society audience showing his papaverine-induced erection. The current most common treatment for ED, the oral PDE5 inhibitor known as sildenafil (Viagra) was approved for use for Pfizer by the FDA in 1998, which at the time of release was the fastest selling drug in history. Sildenafil largely replaced SSRI treatments for ED at the time and proliferated new types of specialised pharmaceutical marketing which emphasised social connotations of ED and Viagra rather than its physical effects.
AaH I is a hemorrhagic toxin which means it causes internal bleeding by damaging blood vessels. AaH I damages the walls of capillaries, causes them to leak blood internally, leading to death. Hemorrhagic toxins are common among other snake venoms as well like rattlesnakes and the western diamondback. There are four different types of AaH in Agkistrodon acutus venom, with AaH I being the strongest hemorrhagic one. Its proteolytic activity was sensitive to pH where it was 100 times stronger in weak alkaline conditions at pH 7.5. This is referring to the break down of proteins through the enzyme proteases. Aah I has three disulfide connections at Cys117-Cys197, Cys159-Cys181 and Cys157-Cys164. There is also one calcium ion, zinc ion, and three histidine zinc ligation in the structure. Each member of the metzincins has a zinc ion in its active site. Metzincins family is metalloproteinases that use a zinc ion in the enzymatic reaction. The zinc binding in AaH I is tetrahedral, three imidazole nitrogen atoms of histidine and one oxygen atom. It is unknown whether this oxygen atom is a water molecule or a hydroxide ion. A calcium ion occurs on the surface of the AaH I molecule opposite to the active-site cleft and close to the crossover point of the N-terminal and the C-terminal segment. Its position close to the C terminus, this calcium ion in the multi-domain parent structure could well play an important role in stabilizing and tightening the segment connecting the proteolytic domain with the succeeding disintegrin domain.
12 pins for the main link – the main link consists of four shielded twisted pairs. Each pair requires 3 pins; one for each of the two wires, and a third for the shield. (pins 1–12) 2 additional ground pins – (pins 13 and 14) 3 pins for the auxiliary channel – the auxiliary channel uses another 3-pin shielded twisted pair (pins 15–17) 1 pin for HPD – hot-plug detection (pin 18) 2 pins for power – 3.3 V power and return line (pins 19 and 20)
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.
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.