The short version of RP-HPLC fits in a sentence. The long version — which is the one that helps — is below.
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Semax is a synthetic heptapeptide developed in the Soviet Union during the 1980s by researchers at the Institute of Molecular Genetics in Moscow. It was designed as a truncated analog of adrenocorticotropic hormone, retaining only the fragment spanning residues four through ten. Investigators sought a peptide that would preserve the cognitive effects associated with ACTH while eliminating the hormonal stimulation of the adrenal cortex. The compound entered clinical use in Russia during the following decade.
Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.
Identity and purity of semax are established with reversed-phase high-performance liquid chromatography coupled to ultraviolet detection, usually at 214 nanometres. Mass spectrometry, most often electrospray ionisation in positive mode, confirms the molecular mass and reveals truncated sequences. Amino acid analysis and peptide mapping after enzymatic digestion provide additional structural confirmation. Laboratories typically report purity as the percentage area of the main peak, a figure that does not capture isomeric or oxidised variants unless the method resolves them.
The peptide is prone to several degradation pathways. Oxidation of the methionine residue produces a sulfoxide that elutes close to the parent peak in many chromatographic systems. Hydrolysis of peptide bonds and deamidation of susceptible residues in related sequences also reduce purity over time. Lyophilised material kept dry at minus twenty degrees Celsius and shielded from light is the most stable form commonly described in laboratory practice.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Analog of an ACTH fragment |
| Amino acid length | Seven residues | Met-Glu-His-Phe-Pro-Gly-Pro |
| Origin | Moscow, 1980s | Institute of Molecular Genetics |
| Approved regions | Russia and some neighboring states | Not cleared in Western markets |
| Common trade names | Multiple national brands | Sold as a nasal formulation |
Clinical reports describe use in ischaemic stroke, transient ischaemic attack, optic nerve conditions, and cognitive complaints, but most of these studies are small and were conducted in a single region. Systematic reviews have generally described the evidence base as limited in size and variable in methodological quality. Randomised controlled data suitable for international regulatory assessment are scarce. As a result, major treatment guidelines outside Russia do not include the peptide, and interest in it remains largely research-driven rather than routine clinical.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It is described in the literature as an analogue of the ACTH(4–10) fragment, a short N-terminal portion of adrenocorticotropic hormone that retains some neurotropic activity without the full hormonal effects of the parent peptide. The molecule carries a methionine residue at the N-terminus and two proline residues near the C-terminus, features that shape both its interactions with receptor systems and its chemical stability. The free peptide corresponds to the formula C37H51N9O10S and a molecular mass near 813.9 Da.
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.
== Presentation == The symptoms of Rabson–Mendenhall syndrome vary from case to case. Major symptoms of Rabson–Mendenhall syndrome include abnormalities of the teeth and nails, such as dental dysplasia, and deformities of the head and face, which include a coarse prematurely-aged facial appearance with a prominent jaw. A skin abnormality known as acanthosis nigricans, which involves a discoloration (hyperpigmentation) and "velvety" thickening (hyperkeratosis) of the skin around skin fold regions of the neck, groin and under arms is also a common symptom. Symptoms will negatively impact the daily life of the patient, and will persist until treated. Minor symptoms may include an enlargement of the genitalia and precocious puberty and a deficiency or absence of fat tissue. Because individuals with Rabson–Mendenhall syndrome fail to use insulin properly, they may experience abnormally high blood sugar levels (hyperglycemia) after eating a meal, and abnormally low blood sugar levels (hypoglycemia) when not eating.
From here he would address 180,000 listeners, some standing in the central round arena, others seated in three concentric tiers of seats crowned by one hundred marble pillars, 24 metres (79 ft) tall, which rose to meet the base of the coffered ceiling suspended from steel girders sheathed on the exterior with copper. The three concentric tiers of seats enclosing a circular arena 140 metres (460 ft) in diameter owe nothing to the Pantheon but resemble the seating arrangements in Ludwig Ruff's Congress Hall at Nuremberg, which was modeled on the Colosseum. Other features of the Volkshalle's interior are clearly indebted to Hadrian's Pantheon: the coffered dome, the pillared zone, which here is continuous, except where it flanks the huge niche on the north side. The second zone in the Pantheon, consisting of blind windows with intervening pilasters, is represented in Speer's building by a zone above the pillars consisting of uniform, oblong shallow recesses. The coffered dome rests on this zone. The design and size of the external decoration of this Volkshalle, are all exceptional and call for explanations that do not apply to community halls planned for Nazi fora in other German cities. The temple-like nature of the domed building was noted by Speer, who surmised that the building was ultimately intended for public worship of Hitler, his successors and the German Reich, that is, it was to be a dynastic temple/palace complex of the kind Augustus built on the Palatine, where his modest house was connected to the temple of Apollo.
Coral Reefs The Ocean Portal by the Smithsonian Institution NOAA – Coral Reef Conservation Program NOAA CoRIS – Coral Reef Biology NOAA Office for Coastal Management – Fast Facts – Coral Reefs NOAA Ocean Service Education – Corals "What is a coral?". Stanford microdocs project. Archived from the original on 2014-01-06. Retrieved 2017-02-04.
Sources: en.wikipedia.org
The α-globin chains are encoded by two closely linked genes HBA1 and HBA2 on chromosome 16; in a person with two copies on each chromosome, a total of four loci encode the α chain. Two alleles are maternal and two alleles are paternal in origin. Alpha-thalassemias result in decreased alpha-globin production, resulting in an excess of β chains in adults and excess γ chains in fetus and newborns.
endocytosis Any process by which a substance is actively uptaken by or brought inside of a cell, crossing the plasma membrane from an extracellular space into an intracellular space, which includes the subclasses of pinocytosis, phagocytosis, and receptor-mediated processes. All of these involve surrounding an extracellular molecule, protein, or even another cell or organism with an extension or invagination of the cell membrane, which then "buds off" or separates from the rest of the membrane on the cytoplasmic side, forming a membrane-enclosed vesicle containing the ingested materials. By this mechanism the material can cross the lipid bilayer without being exposed to the hydrophobic space in between, instead remaining suspended in the fluid of the extracellular space. Many large, polar macromolecules which cannot simply diffuse across the membrane, such as metabolites and hormones, are transported into the cell by endocytosis. It is distinguished from alternative routes such as passing through protein channels or being chaperoned by transport proteins. The reverse process is called exocytosis.
A DNA sequence is called a "sense" sequence if it is the same as that of a messenger RNA copy that is translated into protein. The sequence on the opposite strand is called the "antisense" sequence. Both sense and antisense sequences can exist on different parts of the same strand of DNA (i.e. both strands can contain both sense and antisense sequences). In both prokaryotes and eukaryotes, antisense RNA sequences are produced, but the functions of these RNAs are not entirely clear. One proposal is that antisense RNAs are involved in regulating gene expression through RNA-RNA base pairing. A few DNA sequences in prokaryotes and eukaryotes, and more in plasmids and viruses, blur the distinction between sense and antisense strands by having overlapping genes. In these cases, some DNA sequences do double duty, encoding one protein when read along one strand, and a second protein when read in the opposite direction along the other strand. In bacteria, this overlap may be involved in the regulation of gene transcription, while in viruses, overlapping genes increase the amount of information that can be encoded within the small viral genome.
Sources: en.wikipedia.org
. The sign of the parameter will depend on the sign of the constant potential at each step, and the appropriate matrix will depend on the sign of the parameter. Because a digital waveform may be approximated as existing in only high and low states (potential sign), the stability of ions, as demonstrated by Brabeck, may be determined in as few as two or three constant potential steps. In the simple but frequent case that a full cycle of a digital waveform can be represented by two constant potential steps, the matrix representing the first potential step would be multiplied onto the matrix representing the second potential step. In the general case, the final matrix of a waveform cycle defined by n constant potential steps is:
== Gameplay == Half-Life Alyx is a first-person shooter played in virtual reality (VR). Players control the Resistance member Alyx Vance, who fights the Combine, an alien empire that has conquered Earth. Like previous Half-Life games, Alyx incorporates combat, puzzles, exploration and narrative. Players use VR to get supplies, use interfaces, throw objects and use weapons. Like the gravity gun from Half-Life 2, the gravity gloves allow players to pick up objects from a distance. By solving hacking puzzles, Alyx can interact with Combine technology. Alyx includes elements of survival horror, with frightening encounters and scarce ammunition. In one chapter, players encounter Jeff, a blind monster attracted to sound, and must move quietly and throw objects to distract him. Alien spores in the area cause Alyx to cough, which players can prevent by holding their hands over their mouths. Alyx supports all VR headsets compatible with SteamVR, including the Valve Index, HTC Vive, Oculus Rift, Meta Quest and all Windows Mixed Reality headsets. As the gameplay was designed for VR, Valve said they had no plans for a non-VR version. Alyx also supports user mods via the Steam Workshop.
AC/DC, an Australian rock music group ACDC (medicine), Arterial calcification due to deficiency of CD73 (ACDC), a rare genetic disorder Adiponectin, a peptide hormone All Campus Dining Center, a dining hall at Vassar College Asian Community Development Corporation, a community development organization headquartered in Boston ACDC (JoJo's Bizarre Adventure), also Esidisi, a character from the Japanese manga and anime JoJo's Bizarre Adventure in the story arc Battle Tendency ACDC, a dance crew led by Adam G. Sevani and Jon M. Chu Africa CDC, Africa Centres for Disease Control and Prevention Asymmetric counteranion directed catalysis, a type of chemical reaction
Including the continued aerial slaughter over Orote Field, Japanese losses exceeded 350 planes on the first day of battle. About 30 American planes were lost, and there was little damage to American ships; even the damaged South Dakota was able to remain in formation to continue her anti-aircraft duties.
Sources: en.wikipedia.org
It originated at the Institute of Molecular Genetics in Moscow during the 1980s. The work was carried out by a Russian research group that specialized in peptide neuropharmacology.
It is registered as a medicine in Russia and has been used clinically there for decades. No regulatory agency in Western Europe or North America has approved it for any indication.
Semax corresponds to the four-to-ten fragment of adrenocorticotropic hormone. Because it omits the first three residues, it lacks the adrenal-stimulating action of the full hormone.
Reversed-phase high-performance liquid chromatography is the standard method, with detection in the ultraviolet range. Peak area percentage yields a purity figure for the main component. Mass spectrometry is normally run alongside to confirm molecular identity.