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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.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
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.
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.
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.
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.
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.
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.
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.
=== Traditional methods === Mazatec shamans crush the leaves to extract leaf juices from about 20 to 80 or more fresh leaves (i.e. about 50–200 g or 2–7 oz). They usually mix these juices with water to create an infusion or 'tea' which they drink to induce visions in ritual healing ceremonies. Chewing and swallowing a large number of fresh leaves is the other Mazatec method. Oral consumption of the leaf makes the effects come on more slowly, over a period of 10 to 20 minutes. The experience, from the onset of effects, lasts from about 30 minutes up to one and a half hours. Doses for chewing vastly exceed doses used for smoking. By calculating the concentrations per leaf ("an average concentration of 2.45 mg per gram" of leaf), the average weight per leaf ("about 50 g" per 20 leaves, or 2.5 g/leaf), and the standard dose for chewing (about 8–28 leaves), the doses can range from about 50 mg to 172 mg.
Toxicodynamics (TD) and pharmacodynamics (PD) link a therapeutic agent or toxicant, or toxin (xenobiotic)'s dosage to the features, amount, and time course of its biological action. The mechanism of action is a crucial factor in determining effect and toxicity of the drug, taking in consideration the pharmacokinetic (PK) factors. The sort and extent of altered cellular physiology will depend on the combination of the drug's presence (as established by pharmacokinetic (PK) studies) and/or its mechanism and duration of action (PD). Types of xenobiotic-target interaction can be described either by reversible, irreversible, noncompetitive, and allosteric interaction or agonist, partial agonist, antagonist, and inverse interactions. In vitro, ex vivo, or in vivo studies can be used to assess PD and TD from the molecule to the level of the entire organism. The mechanism of drug action and adverse drug reaction is either physiochemical property based and biochemical based. Adverse drugs reactions can be classified as either idiosyncratic (type B) or intrinsic (type A). Idiosyncratic toxicity is not dosage dependent and defy the mass-action relationship. Immune-mediated processes are frequently cited as the source of type B reactions. These cannot be accurately described in preclinical research or clinical trials due to their low incidence frequency. Type A reactions are dosage (concentration) dependent. Usually, this kind of side effect is an extension of an ongoing treatment.
Non-focal symptoms such as amnesia, confusion, incoordination of limbs, unusual cortical visual symptoms (such as isolated bilateral blindness or bilateral positive visual phenomena), headaches and transient loss of consciousness are usually not associated with TIA, however patient assessment is still needed. Public awareness on the need to seek a medical assessment for these non-focal symptoms is also low, and can result in a delay by patients to seek treatment Symptoms of TIAs can last on the order of minutes to one–two hours, but occasionally may last for a longer period of time. TIA is defined as ischemic events in the brain that last less than 24 hours. Given the variation in duration of symptoms, this definition holds less significance. A pooled study of 808 patients with TIAs from 10 hospitals showed that 60% lasted less than one hour, 71% lasted less than two hours, and 14% lasted greater than six hours. Importantly, patients with symptoms that last more than one hour are more likely to have permanent neurologic damage, making prompt diagnosis and treatment important to maximize recovery.
Allergic reaction: There have been several studies conducted that show a precedence for allergenicity of silver nanoparticles. Argyria and staining: Ingested silver or silver compounds, including colloidal silver, can cause a condition called argyria, a discoloration of the skin and organs.In 2006, there was a case study of a 17-year-old man, who sustained burns to 30% of his body, and experienced a temporary bluish-grey hue after several days of treatment with Acticoat, a brand of wound dressing containing silver nanoparticles. Argyria is the deposition of silver in deep tissues, a condition that cannot happen on a temporary basis, raising the question of whether the cause of the man's discoloration was argyria or even a result of the silver treatment. Silver dressings are known to cause a "transient discoloration" that dissipates in 2–14 days, but not a permanent discoloration. Silzone heart valve: St. Jude Medical released a mechanical heart valve with a silver coated sewing cuff (coated using ion beam-assisted deposition) in 1997. The valve was designed to reduce the instances of endocarditis. The valve was approved for sale in Canada, Europe, the United States, and most other markets around the world. In a post-commercialization study, researchers showed that the valve prevented tissue ingrowth, created paravalvular leakage, valve loosening, and in the worst cases explantation. After 3 years on the market and 36,000 implants, St. Jude discontinued and voluntarily recalled the valve.
Sources: en.wikipedia.org
== History == In 1909 Minnie Evangeline Jordon established the first dental practice in the United States devoted only to pediatric patients. In 1925 she published the first textbook on pediatric dentistry, titled Operative Dentistry for Children. The first dental care brought to public school was Alfred Fones in 1914, which was near 6 decades after the first woman, Lucy Hobbs Taylor, who received a DDS.
Tsukihi Aragami (荒神 月燈, Aragami Tsukihi) Special Agent of National Security. She's the captain of Kaguya's security. She was only appointed to this role temporarily, but she has deep respect and affection for him. She grew up in a family devoted to the gods.
Autoimmune disease A condition in which the immune system inappropriately attacks a body tissue. Multiple sclerosis, some kinds of rheumatism, lupus, and Type 1 diabetes are examples. The reasons for the immune system misbehavior are not, in general, understood. Autonomic neuropathy Damage to nerves that do not control senses or muscles. These nerves control 'automatic' processes, like heart rate and body temperature. They can be damaged by diabetes, just like 'regular' somatic nerves, but the results are 'system-wide', not just pain or muscle weakness. Balance, intestinal control, blood pressure regulation, sweating, breathing rate, ... are all controlled or influenced by the autonomic nervous system.
Sources: en.wikipedia.org
== Treatment == The key for managing Sack–Barabas syndrome is for the affected person to be aware of their disease. Close follow up and planning of interventions can significantly prolong and maintain the quality of life of a person with vEDS. Pregnant affected women must take special care due to the increased risk of premature death due to rupture of arteries, bowel or uterine rupture, with a reported mortality rate of 50%. Genetic counseling is recommended for prospective parents with a family history of Ehlers–Danlos syndrome. Affected parents should be aware of the type of Ehlers-Danlos syndrome they have and its mode of inheritance.
=== H: Diseases of the eye, adnexa, ear, and mastoid process === (H04.6) Lacrimal fistula (H05.81) Carotid cavernous fistula (H70.1) Mastoid fistula Craniosinus fistula: between the intracranial space and a paranasal sinus (H83.1) Labyrinthine fistula Perilymph fistula: tear between the membranes between the middle and inner ears Preauricular fistula Preauricular fistula: usually on the top of the cristae helicis of the ears
where A = 0.02939 mPa·s, B = 507.88 K, and C = 149.3 K. Experimentally determined values of the viscosity are also given in the table below. The values at 20 °C are a useful reference: there, the dynamic viscosity is about 1 cP and the kinematic viscosity is about 1 cSt.
Years after its creation, Villaverde wrote: "It was suggested that this should include the All-Seeing-Eye, but Brother Lopez objected that it would be too difficult to work in silk and bunting." So, instead of the Eye, they chose the shape of the Lone Star of Texas to be placed on the equilateral triangle. Albert Mackey, who in 1859 was heavily involved in Freemasonry to Cuba, wrote about the relevance of the triangle and the pyramid to Freemasonry. Narciso López and Miguel Teurbe Tolón also collaborated on the Coat of arms of Cuba.
Sources: en.wikipedia.org
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.