intranasal delivery raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-11-25. Anything still debated is marked as such rather than presented as settled.
The mechanisms attributed to semax are inferred from animal and cell studies rather than traced to one confirmed target. The most frequently cited pathway involves increased expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal and cortical tissue. Some work points to engagement of melanocortin receptors, particularly MC4, which the parent ACTH fragment can activate. Effects on dopaminergic and serotonergic signalling have also been reported. No single account explains all observed results, and the relative weight of each pathway remains unsettled.
Published studies examine a fairly narrow set of endpoints. Rodent experiments commonly measure maze learning, infarct volume after induced ischemia, and tissue levels of neurotrophic factors. Clinical reports from Russian centres describe attention, memory and recovery scores in patients after stroke or transient ischemic attack. Most of those human studies are small and few have been repeated by independent groups. Outcome measures differ between studies, which limits direct comparison.
Circulation time for the peptide is short because peptidases cleave it readily. The Pro-Gly-Pro tail is thought to slow breakdown compared with the bare ACTH fragment, but the gain appears modest. Absorption after intranasal dosing is limited, and only a fraction of a dose is expected to reach the central nervous system. Laboratory concentrations therefore sit well above levels achieved systemically, a gap that complicates translation from bench findings to clinical claims.
Identity and purity of Semax are established mainly by reversed-phase high-performance liquid chromatography coupled with mass spectrometry. The chromatographic trace gives a purity estimate as a percentage of total peak area, while electrospray or matrix-assisted laser desorption ionization confirms the molecular mass against the calculated value. Amino acid analysis and sequence-specific fragmentation provide further confirmation when a supplier's chain of custody is unclear. Vendors frequently quote a purity figure without stating the detection wavelength or the integration method, which limits how far one number can be compared with another.
Stability depends heavily on physical state. Lyophilized powder held dry, cold and dark retains its content over long periods, whereas dissolved peptide begins to change within days at room temperature. The most cited degradation route is oxidation of the methionine residue, which converts the peptide to a sulfoxide form that elutes differently on chromatography. Hydrolysis of amide bonds and adsorption onto container walls contribute smaller losses. Buffers that exclude oxygen from the headspace slow the oxidation pathway, but no single condition prevents all change indefinitely.
Practical handling follows from those properties. Bulk material is best divided into single-use portions soon after receipt, because each thaw exposes the whole container to moisture and temperature cycling. Vials should be allowed to reach room temperature before opening to prevent condensation on the powder. Low-binding plasticware reduces loss of dilute solutions, and sterile filtration is used when a preparation must remain free of microbial growth. Records of batch number, reconstitution date and storage history are what allow a later analytical result to be interpreted meaningfully.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized solid from research suppliers |
| Solubility | Freely soluble in water | Also dissolves in aqueous buffers; solutions are used fresh |
| Typical storage temperature | -20 °C for lyophilized powder | Short-term transport at 2-8 °C is common |
| Common analytical method | Reverse-phase HPLC | Paired with mass spectrometry for identity confirmation |
| Common synonyms | ACTH(4-10) analogue; MEHFPGP | N-terminal methionine retained in the chain |
=== Free radical === The deamination of an alanine molecule produces the free radical CH3C•HCO2−. Deamination can be induced in solid or aqueous alanine by radiation that causes homolytic cleavage of the carbon–nitrogen bond. This property of alanine is used in dosimetric measurements in radiotherapy. When normal alanine is irradiated, the radiation causes certain alanine molecules to become free radicals, and, as these radicals are stable, the free radical content can later be measured by electron paramagnetic resonance in order to find out how much radiation the alanine was exposed to. This is considered to be a biologically relevant measure of the amount of radiation damage that living tissue would suffer under the same radiation exposure. Radiotherapy treatment plans can be delivered in test mode to alanine pellets, which can then be measured to check that the intended pattern of radiation dose is correctly delivered by the treatment system.
=== Definitions and general characteristics === In a hydrogen bond, the electronegative atom not covalently attached to the hydrogen is named the proton acceptor, whereas the one covalently bound to the hydrogen is named the proton donor. This nomenclature is recommended by the IUPAC. The hydrogen of the donor is protic and therefore can act as a Lewis acid and the acceptor is the Lewis base. Hydrogen bonds are represented as H···Y system, where the dots represent the hydrogen bond. Liquids that display hydrogen bonding (such as water) are called associated liquids.
Octopuses use camouflage to hunt and to avoid predators. To do this, they use specialised skin cells that change colour. Chromatophores contain yellow, orange, red, brown, or black pigments; most species have three of these colours, while some have two or four. Other colour-changing cells are reflective iridophores and white leucophores. This colour-changing ability is also used to communicate with or warn other octopuses. The energy cost of the complete activation of the chromatophore system is high, nearly matching the energy used at rest. Octopuses can create distracting patterns with waves of dark colouration across the body, a display known as the "passing cloud". Muscles in the skin change the texture of the mantle to achieve greater camouflage. In some species, the mantle can take on the bumpy appearance of algae-covered rocks. Diurnal, shallow water octopuses have more complex skin than their nocturnal and deep-sea counterparts. In the latter species, skin anatomy is limited to one colour or pattern. Octopus' "moving rock" trick involves mimicking a rock and then inching across the open space with a speed matching that of the surrounding water.
Sources: en.wikipedia.org
=== Detection in body fluids === Mephedrone may be quantitated in blood, plasma or urine by gas chromatography-mass spectrometry or liquid chromatography-mass spectrometry to confirm a diagnosis of poisoning in hospitalised patients or to provide evidence in a medicolegal death investigation. Blood or plasma mephedrone concentrations are expected to be in a range of 50–100 μg/L in persons using the drug recreationally, >100 μg/L in intoxicated patients and >500 μg/L in victims of acute overdosage.
Protactinium(V) chloride has a polymeric structure of monoclinic symmetry. There, within one polymeric chain, all chlorine atoms lie in one graphite-like plane and form planar pentagons around the protactinium ions. The 7-coordination of protactinium originates from the five chlorine atoms and two bonds to protactinium atoms belonging to the nearby chains. It easily hydrolyzes in water. It melts at 300 °C and sublimates at even lower temperatures. Protactinium(V) fluoride can be prepared by reacting protactinium oxide with either bromine pentafluoride or bromine trifluoride at about 600 °C, and protactinium(IV) fluoride is obtained from the oxide and a mixture of hydrogen and hydrogen fluoride at 600 °C; a large excess of hydrogen is required to remove atmospheric oxygen leaks into the reaction. Protactinium(V) chloride is prepared by reacting protactinium oxide with carbon tetrachloride at temperatures of 200–300 °C. The by-products (such as PaOCl3) are removed by fractional sublimation. Reduction of protactinium(V) chloride with hydrogen at about 800 °C yields protactinium(IV) chloride – a yellow-green solid that sublimes in vacuum at 400 °C. It can also be obtained directly from protactinium dioxide by treating it with carbon tetrachloride at 400 °C. Protactinium bromides are produced by the action of aluminium bromide, hydrogen bromide, carbon tetrabromide, or a mixture of hydrogen bromide and thionyl bromide on protactinium oxide. They can alternatively be produced by reacting protactinium pentachloride with hydrogen bromide or thionyl bromide.
This is considered to be a hybrid between an exocrine and endocrine tumor derived from crypt cells of the appendix. Histologically, it forms clusters of goblet cells containing mucin with a minor admixture of Paneth cells and endocrine cells. The growth pattern is distinctive: typically producing a concentric band of tumor nests interspersed among the muscle and stroma of the appendiceal wall extending up the shaft of the appendix. This makes the lesion difficult to suspect grossly and difficult to measure. Small tumor nests may be camouflaged amongst the muscle or in periappendiceal fat; cytokeratin preparations best demonstrate the tumor cells; mucin stains are also helpful in identifying them. They behave in a more aggressive manner than do classical appendiceal carcinoids. Spread is usually to regional lymph nodes, peritoneum, and particularly the ovary. They do not produce sufficient hormonal substances to cause carcinoid or other endocrine syndromes. In fact, they more closely resemble exocrine than endocrine tumors. The term 'crypt cell carcinoma' has been used for them, and though perhaps more accurate than considering them carcinoids, has not been a successful competitor.
26 January 1919: Great Polish Army soldiers, commanded by Dowbór-Muśnicki, give an oath on Wilhelm Platz, renamed on Plac Wolności (Freedom Square), in Poznań. 28 January 1919: German offensive ("Butteroffensive") in area of Bydgoszcz and Nakło. In the Battle of Rynarzewo, the Germans capture Szubin.
Sources: en.wikipedia.org
It consists mainly of animal experiments and small clinical reports, with much of the clinical material published in Russian-language journals. Large independent trials are scarce. Separating reliable effects from chance findings is consequently difficult.
A fraction of an intranasal dose is thought to reach the central nervous system, and this route is favoured partly for that reason. The proportion is not well characterized. Direct measurement in humans remains difficult with current methods.
Raised BDNF and NGF expression has been reported across several animal studies, which makes the signal fairly consistent. Whether the same change occurs in humans at usable doses is not established. It is best treated as a working hypothesis rather than a confirmed clinical mechanism.
Suppliers normally quote a percentage of total chromatographic peak area, most often from reversed-phase HPLC. That figure says nothing about what the remaining percentage contains, and it depends on the detection wavelength used. A mass spectrometry result is a separate and stronger check on identity.