This is a working overview of intranasal delivery, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Dry storage temperature | -20 C or below | Sealed, desiccated, protected from light |
| Solution stability | Hours to days at 2-8 C | Depends on buffer and microbial load |
| Preferred pH range | Near neutral to slightly acidic | Alkaline pH accelerates hydrolysis |
| Main degradation routes | Hydrolysis and deamidation | No cysteine or methionine in sequence |
| Identity confirmation | Electrospray mass spectrometry | Observed mass compared with 751.9 Da |
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.
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.
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.
Histology, also known as microscopic anatomy, microanatomy or histoanatomy, is the branch of biology that studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures visible without a microscope. Historically, microscopic anatomy was divided into organology, the study of organs, histology, the study of tissues, and cytology, the study of cells, although modern usage places all of these topics under the field of histology. In medicine, histopathology is the branch of histology that includes the microscopic identification and study of diseased tissue. In the field of paleontology, the term paleohistology refers to the histology of fossil organisms.
Einsteinium is produced in minute quantities by bombarding lighter actinides with neutrons in dedicated high-flux nuclear reactors. The world's major irradiation sources are the 85-megawatt High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL), Tennessee, U.S., and the SM-2 loop reactor at the Research Institute of Atomic Reactors (NIIAR) in Dimitrovgrad, Russia, which are both dedicated to the production of transcurium (Z>96) elements. These facilities have similar power and flux levels, and are expected to have comparable production capacities for transcurium elements, though the quantities produced at NIIAR are not widely reported. In a "typical processing campaign" at ORNL, tens of grams of curium are irradiated to produce decigram quantities of californium, milligrams of berkelium (249Bk) and einsteinium and picograms of fermium. The first microscopic sample of 253Es weighing about 10pr nanograms was prepared in 1961 at HFIR. A special magnetic balance was designed to estimate its weight. Larger batches were produced later starting from several kilograms of plutonium with the einsteinium yields (mostly 253Es) of 0.48 milligram in 1967–1970, 3.2 milligrams in 1971–1973, followed by steady production of about 3 milligrams per year between 1974 and 1978. These quantities however refer to the integral amount in the target right after irradiation. Subsequent separation procedures reduced the amount of isotopically pure einsteinium roughly tenfold.
== Structure == MHC class I molecules are heterodimers that consist of two polypeptide chains, α and β2-microglobulin (B2M). The two chains are linked noncovalently via interaction of B2M and the α3 domain. Only the α chain is polymorphic and encoded by a HLA gene, while the B2M subunit is not polymorphic and encoded by the beta-2 microglobulin gene. The α3 domain is plasma membrane-spanning and interacts with the CD8 co-receptor of T-cells. The α3-CD8 interaction holds the MHC I molecule in place while the T cell receptor (TCR) on the surface of the cytotoxic T cell binds its α1-α2 heterodimer ligand, and checks the coupled peptide for antigenicity. The α1 and α2 domains fold to make up a groove for peptides to bind. MHC class I molecules bind peptides that are predominantly 8-10 amino acid in length (Parham 87), but the binding of longer peptides have also been reported. While a high-affinity peptide and the B2M subunit are normally required to maintain a stable ternary complex between the peptide, MHC I, and B2M, under subphysiological temperatures, stable, peptide-deficient MHC I/B2M heterodimers have been observed. Synthetic stable, peptide-receptive MHC I molecules have been generated using a disulfide bond between the MHC I and B2M, named "open MHC-I".
Since the 1980s, spice heat has been assessed quantitatively by high-performance liquid chromatography (HPLC), which measures the concentration of heat-producing capsaicinoids, typically with capsaicin content as the main measure. As stated in one review "the most reliable, rapid, and efficient method to identify and quantify capsaicinoids is HPLC; the results of which can be converted to Scoville heat units by multiplying the parts-per-million by 16." HPLC method gives results in American Spice Trade Association 1985 "pungency units", which are defined as one part capsaicin equivalent per million parts dried pepper mass. This "parts per million of heat" (ppmH) is found with the following calculation:
Sources: en.wikipedia.org
=== Sheep === In sheep, ketosis, evidenced by hyperketonemia with beta-hydroxybutyrate in blood over 0.7 mmol/L, is referred to as pregnancy toxemia. This may develop in late pregnancy in ewes bearing multiple fetuses and is associated with the considerable metabolic demands of the pregnancy. In ruminants, because most glucose in the digestive tract is metabolized by rumen organisms, glucose must be supplied by gluconeogenesis. Pregnancy toxemia is most likely to occur in late pregnancy due to metabolic demand from rapid fetal growth and may be triggered by insufficient feed energy intake due to weather conditions, stress or other causes. Prompt recovery may occur with natural parturition, Caesarean section or induced abortion. Prevention through appropriate feeding and other management is more effective than treatment of advanced stages of pregnancy toxemia.
Your excellency, Mr President, I greet you in the name of the many thousands of people in Britain who stood against the tide and opposed the war ... I greet you too in the name of the Palestinian people ... I thought the president would appreciate knowing that even today, three years after the war, I still meet families who are calling their newborn sons Saddam ... Sir, I salute your courage, your strength, your indefatigability. And I want you to know that we are with you until victory, until victory, until Jerusalem (hatta al-nasr, hatta al-nasr, hatta al-Quds). During Galloway's 2004 defamation case against the Daily Telegraph, the paper's defence Queen's Counsel accused Galloway of having "fawned over" Saddam during their meeting in 1994. Labour leader John Smith said: "I deeply deplore the foolish statement made in Iraq by Mr. George Galloway. In no way did he speak for the Labour Party and I wholly reject his comments". Galloway said that he was saluting the Iraqi people, rather than Saddam Hussein, and Galloway's friend Anas Altikriti observed that this is how it was translated for Saddam. Shortly after his return, Galloway was given a "severe reprimand" and "final warning" by the Labour Chief Whip, Derek Foster. Galloway apologised for his conduct and undertook to follow future instruction from the whips. For his meeting with Saddam, Galloway was dubbed the "MP for Baghdad North". When he spoke before the U.S.
Meanwhile, life cycle reversal, in which polyps are formed directly from medusae without the involvement of sexual reproduction process, was observed in both Hydrozoa (Turritopsis dohrnii and Laodicea undulata) and Scyphozoa (Aurelia sp.1). Anthozoa have no medusa stage at all and the polyps are responsible for sexual reproduction. Spawning is generally driven by environmental factors such as changes in the water temperature, and their release is triggered by lighting conditions such as sunrise, sunset or the phase of the moon. Many species of Cnidaria may spawn simultaneously in the same location, so that there are too many ova and sperm for predators to eat more than a tiny percentage — one famous example is the Great Barrier Reef, where at least 110 corals and a few non-cnidarian invertebrates produce enough gametes to turn the water cloudy. These mass spawnings may produce hybrids, some of which can settle and form polyps, but it is not known how long these can survive. In some species the ova release chemicals that attract sperm of the same species. The fertilized eggs develop into larvae by dividing until there are enough cells to form a hollow sphere (blastula) and then a depression forms at one end (gastrulation) and eventually becomes the digestive cavity. However, in cnidarians the depression forms at the end further from the yolk (at the animal pole), while in bilaterians it forms at the other end (vegetal pole). The larvae, called planulae, swim or crawl by means of cilia.
Sources: en.wikipedia.org
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.
Hydrolysis of peptide bonds and deamidation of arginine and proline residues are the main degradation routes. Alkaline pH and higher temperatures accelerate both processes. Buffered, near-neutral solutions stored cold generally degrade more slowly than unbuffered ones.
Reverse-phase chromatography gives the clearest single view of related impurities and truncated sequences. Mass spectrometry then confirms that the main peak carries the expected mass. Neither test detects enantiomeric impurities, which require a separate chiral assay.
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.