A practical reference on blood-brain barrier: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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.
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.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
| Property | Value | Notes |
|---|---|---|
| Primary route studied | Intranasal | Also examined parenterally in animal work |
| Reported plasma half-life | Minutes to tens of minutes | Values vary widely between reports |
| Main model systems | Rodent behavioural and cell assays | Human trials are few and small |
| Principal proposed targets | GABA-A receptor, GABA transaminase | Monoamine and neurotrophic pathways also reported |
| Evidence grade | Preliminary | Limited independent replication |
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.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
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.
Activated carbon, in 50% w/w combination with celite, is used as stationary phase in low-pressure chromatographic separation of carbohydrates (mono-, di-, tri-saccharides) using ethanol solutions (5–50%) as mobile phase in analytical or preparative protocols. Activated carbon is useful for extracting the direct oral anticoagulants (DOACs) such as dabigatran, apixaban, rivaroxaban and edoxaban from blood plasma samples. For this purpose it has been made into "minitablets", each containing 5 mg activated carbon for treating 1ml samples of DOAC. Since this activated carbon has no effect on blood clotting factors, heparin or most other anticoagulants this allows a plasma sample to be analyzed for abnormalities otherwise affected by the DOACs. Carbon adsorption has numerous applications in removing pollutants from air or water streams both in the field and in industrial processes such as:
RNA polymerase III performs "intrinsic-like" termination. The majority of genes transcribed by RNAP III have a poly(dT) region. However, although poly(dT) pauses every RNA polymerase, it alone cannot be insufficient; some other mechanism must destabilize the clamp. In RNAP III, some poly(dT) sites are indeed occasionally read-through: some genes have multiple such regions, allowing transcripts of different lengths to be produced. The instability of rU:dA hybrids likely is essential to termination by RNAP III. Parts of core subunits C1 and C2, as well as "subcomplexes" C53/37 and C11 are functionally important. A number of extraneous factors can modify the termination behavior. Rho factor WebGeSTer Trp operon
==== Legal challenges ==== In Glossip v. Gross, attorneys for three Oklahoma inmates argued that midazolam could not achieve the level of unconsciousness required for surgery, meaning severe pain and suffering was likely. They argued that midazolam was cruel and unusual punishment and thus contrary to the Eighth Amendment to the United States Constitution. In June 2015, the U.S. Supreme Court ruled that they had failed to prove that midazolam was cruel and unusual when compared to known, available alternatives. The state of Nevada is also known to use midazolam in execution procedures. In July 2018, one of the manufacturers accused state officials of obtaining the medication under pretences. This incident was the first time a drug company successfully, though temporarily, halted an execution. A previous attempt in 2017, to halt an execution in the state of Arizona by another drug manufacturer was not successful.
Add-on therapy in patients with renal impairment RI in T2DM limits the usable medications for lowering glucose level and requires frequent monitoring of renal function. Gemigliptin has balanced elimination between urinary/fecal excretion and hepatic metabolism; therefore, it does not require dose adjustment in patient with moderate to severe RI. This study evaluated the efficacy and safety of gemigliptin in T2DM patients with moderate to severe RI. This randomized, blinded, parallel group, phase IIIb study (study identifier: LG-DPCL015, GUARD study; ClinicalTrials.gov registration number: NCT01968044) was composed of a 12-week, placebo controlled period, followed by a 40-week, blinded active controlled extension period (placebo switched to linagliptin). A total of 132 patients with moderate or severe RI were randomized to receive gemigliptin (n=66) or placebo (n=66). Insulin was used as predominant background therapy (63.1%). At week 12, the placebo-adjusted mean change in HbA1c from the baseline was –1.20% (95% CI, –1.53 to –0.87; P<0.0001). A similar profile was also observed in other glycemic control parameters (fasting plasma glucose, glycated albumin, and fructosamine). Effects on glycemic variability Glycemic variability and chronic sustained hyperglycemia are the main components of dysglycemia in diabetes. The previous studies suggested that different pharmacodynamic profiles between DPP-4 inhibitors have been associated with the different effects on glycemic variability.
Sources: en.wikipedia.org
=== Chromatography === Liquid chromatography is an important tool in the study of the proteome. It allows for very sensitive separation of different kinds of proteins based on their affinity for a matrix. Some newer methods for the separation and identification of proteins include the use of monolithic capillary columns, high temperature chromatography and capillary electrochromatography.
is the mass of the solids. For materials that change in volume with water content, such as coal, the gravimetric water content, u, is expressed in terms of the mass of water per unit mass of the moist specimen (before drying):
=== Non-challenge blood glucose tests === When a plasma glucose level is found to be higher than 126 mg/dL (7.0 mmol/L) after fasting, or over 200 mg/dL (11.1 mmol/L) on any occasion, and if this is confirmed on a subsequent day, the diagnosis of GDM is made, and no further testing is required. These tests are typically performed at the first antenatal visit. They are simple to administer and inexpensive, but have a lower test performance compared to the other tests, with moderate sensitivity, low specificity, and high false positive rates.
Many industries other than the health industry have used antimicrobial surfaces to keep surfaces clean. The physical nature of the surface or its chemical makeup can be manipulated to create an inhospitable environment for micro-organisms. Photocatalytic materials have been used for their ability to kill many micro-organisms and therefore can be used for self-cleaning surfaces as well as air cleaning, water purification, and antitumor activity.
== Usage and maintenance == Vehicles traveling on ice roads include ordinary automobiles and trucks of various sizes and weights. Standard winter tires are sufficient: in fact cleats and tire chains can damage the road surface. Tire chains may be stored in the vehicle for emergency purposes; they can also come in handy when traveling on a winter road with grades steeper than 8% on over-land segments. Signage may indicate speed limits, for instance a maximum of 25 km/h (16 mph), and spacing between vehicles, for instance 500 m (1,600 ft) for loads more than 12,500 kg (27,600 lb). These restrictions are to decrease the risks of damage to the ice cover, which would compromise its ability to support the weight it has been designed for. Maintenance comprises two main tasks:
Sources: en.wikipedia.org
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.
The peptide enters plasma rapidly and is broken down by ordinary proteases into amino acids and shorter fragments. Reported half-lives are short. Whether meaningful amounts of the intact molecule reach the brain is an open question.
Most clinical reports are small, published in Russian and not independently replicated. English-language reviews highlight the absence of large randomised trials. Conclusions about efficacy should be treated as provisional.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.