The short version of freeze-thaw cycle fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-03-13 and is reviewed periodically as new material appears.
Identity and purity are established with complementary methods rather than one test. Reverse-phase high-performance liquid chromatography separates the main peak from deletion sequences and oxidized variants, and its area percentage is the usual purity figure. Mass spectrometry confirms the expected molecular mass and can flag truncations or modifications that chromatography alone might miss. Amino acid analysis and peptide mapping add sequence-level confirmation, while residual counter-ion and water content are measured separately.
A freeze-dried sample is generally the most stable form and is commonly held at minus twenty degrees Celsius or lower for long-term keeping, with brief transfers at room temperature. The solid is hygroscopic, so vials are warmed to ambient temperature before opening to prevent condensation from degrading the contents. Light exposure and repeated temperature cycling are both avoided in routine handling. Storage over a desiccant is a common laboratory practice that limits moisture uptake during repeated access.
Once dissolved, the material is considerably less stable than the dry solid. Aqueous solutions are usually kept cold and used within a short window, and neutral or mildly acidic buffers are preferred over strongly alkaline conditions. Freeze-thaw cycles promote aggregation and loss of material to container surfaces, so dividing a batch into single-use aliquots is standard. Adsorption to plastic and glass can lower the measured concentration, meaning solution strength may need rechecking before an experiment.
The peptide was first described in the early 1990s by a group studying gastric secretions and tissue repair. Its fifteen-residue chain is usually written as GEPPPGKPADDAGLV in single-letter code. The free peptide has the formula C62H98N16O22 and a theoretical mass near 1419.5 daltons. These identifiers are established chemical facts that can be checked against standard peptide databases. There is no ambiguity about the primary structure.
Most published findings come from rodent experiments using induced injury or surgical models. Human reports remain scarce and are largely observational, which limits how much can be stated with confidence. Questions about absorption, distribution, metabolism, and clearance in people are still open. Dose translation between species is likewise unresolved. Researchers tend to read the animal literature as a starting point rather than a settled account.
| Property | Value | Notes |
|---|---|---|
| Dry powder storage | -20 °C or below | Desiccated and protected from light |
| Solution storage | 2-8 °C, short term | Aliquot to avoid freeze-thaw cycling |
| Reconstitution solvent | Water or buffered saline | Near-neutral pH is generally preferred |
| Identity confirmation | Mass spectrometry | Matches expected monoisotopic mass |
| Purity assessment | Reverse-phase HPLC | Reported as main-peak area percentage |
Identity and purity are checked with standard peptide techniques. Reversed-phase high-performance liquid chromatography separates the main peak from closely related impurities and yields a percentage purity. Mass spectrometry confirms that the measured mass matches the theoretical value. Amino acid analysis offers an independent check on overall composition. These analytical methods characterize the material itself and reveal nothing about how it behaves in a living system.
In its common research form the peptide is supplied as a lyophilized powder. It dissolves readily in water and in typical aqueous buffers, which simplifies preparation of working solutions. Laboratories usually prepare small aliquots instead of one large volume. The dry material appears as a white to off-white solid with no distinctive odor. Bulk quantities are typically shipped in sealed vials.
Early work on this family of molecules examined fractions of human gastric juice, where a larger protein was reported to protect gastrointestinal tissue in animal models. BPC 157 was designed as a shorter, more stable fragment of that protein and then studied on its own. The peptide itself is not a normal dietary component and is not present in the human body in meaningful quantities. Descriptions of its origin therefore refer to the research lineage of a laboratory molecule rather than to an endogenous or nutritional substance.
The sequence contains an unusually high proportion of proline and glycine, which limits regular secondary structure and contributes to solubility in aqueous media. The compound dissolves readily in water and in normal saline. Because it is a peptide, digestive enzymes are expected to break it down if it is swallowed, a consideration that influences the routes of administration used in animal experiments. Detailed conformational data remain limited, and published structural models are largely computational.
This policy has reinforced Paraguay's international alignment with the United States and Israel, although it has generated criticism from sectors warning of possible repercussions for relations with countries of the Arab world and the Global South. In December 2024, Peña attended the reopening of the Paraguayan embassy in Israel in Jerusalem. Domestically, the government's stance was celebrated by figures in the ruling camp as a reaffirmation of shared democratic values, although it also prompted criticism in the Senate from opposition sectors that considered the diplomatic imbalance risky.
The Soviets planned to use the GIUK gap to intercept any NATO ships, especially aircraft carriers, heading towards the Soviet Union. Ships and submarines as well as Tupolev Tu-142 maritime-surveillance aircraft aimed to track any threatening ships. The advent of longer-ranged Soviet submarine-launched ballistic missiles (SLBMs) allowed the Soviet Navy to deploy their ballistic missile submarine (SSBNs) within protected bastions in the Barents Sea and reduced their need to transit the GIUK gap. The much reduced, post-Cold War Russian Navy has even less need to transit the GIUK gap. Crossing the GIUK gap was a major strategic move for Ocean Venture in 1992, in which 84 NATO ships, including 4 US aircraft carriers, departed from their usual August exercise pattern, deployed a decoy south toward the mid-Atlantic, and then entered waters in a move that had historically been associated with a risk of destabilizing détente.
In Hungary, a government advisory body recommended mephedrone should be made illegal in August 2010, which was followed, making it illegal in January 2011; Spain followed in February 2011. Mexico, by decree, outlawed mephedrone as a substance "with low or no therapeutical use which pose[s] a serious threat to public health" in 2014. In some countries, mephedrone is not specifically listed as illegal, but is controlled under legislation that makes compounds illegal if they are analogs of drugs already listed. In Australia during 2010, it was not specifically listed as prohibited, but the Australian Federal Police stated it is an analogue to methcathinone and therefore illegal. It is now listed as a Schedule 9 prohibited substance in Australia under the Poisons Standard (October 2015). A Schedule 9 substance is a substance which may be abused or misused, the manufacture, possession, sale or use of which should be prohibited by law except when required for medical or scientific research, or for analytical, teaching or training purposes with approval of Commonwealth and/or State or Territory Health Authorities. In February 2010, 22 men were arrested in connection with importing mephedrone. By January 2011, every state in Australia, other than Victoria, had listed it as a controlled drug.
The Oddo–Harkins rule holds that elements with even atomic numbers are more common than those with odd atomic numbers, with the exception of hydrogen and beryllium. This rule argues that elements with odd atomic numbers have one unpaired proton and are more likely to capture another, thus increasing their atomic number. In elements with even atomic numbers, protons are paired, with each member of the pair offsetting the spin of the other, enhancing stability. All the alkali metals have odd atomic numbers and they are not as common as the elements with even atomic numbers adjacent to them (the noble gases and the alkaline earth metals) in the Solar System. The heavier alkali metals are also less abundant than the lighter ones as the alkali metals from rubidium onward can only be synthesised in supernovae and not in stellar nucleosynthesis. Lithium is also much less abundant than sodium and potassium as it is poorly synthesised in both Big Bang nucleosynthesis and in stars: the Big Bang could only produce trace quantities of lithium, beryllium and boron due to the absence of a stable nucleus with 5 or 8 nucleons, and stellar nucleosynthesis could only pass this bottleneck by the triple-alpha process, fusing three helium nuclei to form carbon, and skipping over those three elements.
Sources: en.wikipedia.org
In October 2004, an Italian localised edition was launched under the name Videogiochi and published by Future Italy. In December 2006, Future Italy was sold to Sprea Editori which renamed it Game Pro in May 2007. Last issue: September 2009.
Rosiglitazone (trade name Avandia) is an antidiabetic drug in the thiazolidinedione class. It works as an insulin sensitizer, by binding to the PPAR in fat cells and making the cells more responsive to insulin. It is marketed by the pharmaceutical company GlaxoSmithKline (GSK) as a stand-alone drug or for use in combination with metformin or with glimepiride. First released in 1999, annual sales peaked at approximately $2.5 billion in 2006; however, following a meta-analysis in 2007 that linked the drug's use to an increased risk of heart attack, sales plummeted to just $9.5 million in 2012. The drug's patent expired in 2012. It was patented in 1987 and approved for medical use in 1999. Despite rosiglitazone's effectiveness at decreasing blood sugar in type 2 diabetes mellitus, its use decreased dramatically as studies showed apparent associations with increased risks of heart attacks and death. Adverse effects alleged to be caused by rosiglitazone were the subject of over 13,000 lawsuits against GSK; as of July 2010, GSK had agreed to settlements on more than 11,500 of these suits. Some reviewers recommended rosiglitazone be taken off the market, but an FDA panel disagreed, and it remains available in the US. From November 2011 until November 2013, the US federal government did not allow Avandia to be sold without a prescription from a certified doctor; moreover, patients were required to be informed of the risks associated with its use, and the drug had to be purchased by mail order through specified pharmacies.
A given stereocenter has two possible configurations (R and S), which give rise to stereoisomers (diastereomers and enantiomers) in molecules with one or more stereocenter. For a chiral molecule with one or more stereocenter, the enantiomer corresponds to the stereoisomer in which every stereocenter has the opposite configuration. An organic compound with only one stereogenic carbon is always chiral. On the other hand, an organic compound with multiple stereogenic carbons is typically, but not always, chiral. In particular, if the stereocenters are configured in such a way that the molecule can take a conformation having a plane of symmetry or an inversion point, then the molecule is achiral and is known as a meso compound. Molecules with chirality arising from one or more stereocenters are classified as possessing central chirality. There are two other types of stereogenic elements that can give rise to chirality, a stereogenic axis (axial chirality) and a stereogenic plane (planar chirality). Finally, the inherent curvature of a molecule can also give rise to chirality (inherent chirality). These types of chirality are far less common than central chirality. BINOL is a typical example of an axially chiral molecule, while trans-cyclooctene is a commonly cited example of a planar chiral molecule. Finally, helicene possesses helical chirality, which is one type of inherent chirality. Chirality is an important concept for stereochemistry and biochemistry.
As a halogen, astatine tends to be classified as a nonmetal. It has some marked metallic properties and is sometimes instead classified as either a metalloid or (less often) as a metal. Immediately following its production in 1940, early investigators considered it a metal. In 1949 it was called the most noble (difficult to reduce) nonmetal as well as being a relatively noble (difficult to oxidize) metal. In 1950 astatine was described as a halogen and (therefore) a reactive nonmetal. In 2013, on the basis of relativistic modelling, astatine was predicted to be a monatomic metal, with a face-centred cubic crystalline structure. Several authors have commented on the metallic nature of some of the properties of astatine. Since iodine is a semiconductor in the direction of its planes, and since the halogens become more metallic with increasing atomic number, it has been presumed that astatine would be a metal if it could form a condensed phase. Astatine may be metallic in the liquid state on the basis that elements with an enthalpy of vaporization (∆Hvap) greater than ~42 kJ/mol are metallic when liquid. Such elements include boron, silicon, germanium, antimony, selenium, and tellurium. Estimated values for ∆Hvap of diatomic astatine are 50 kJ/mol or higher; diatomic iodine, with a ∆Hvap of 41.71, falls just short of the threshold figure.
Lactobacillic acid, scientifically 10-(2-hexylcyclopropyl) decanoic acid, is a naturally occurring chemical compound from the group of fatty acids. Its salts are called lactobacillates. A special feature is the cyclopropane ring in the carbon chain. Lactobacillic acid, with 19 carbon atoms, is an odd-chain fatty acid. The fatty acid was detected in the 1950s in bacteria of the genus Lactobacillus, but is also found in numerous other bacterial species. The bacterial biosynthesis of lactobacillic acid takes place from cis-vaccenic acid (cis-11-octadecenoic acid), a unsaturated fatty acid that has one carbon atom less. Bacteria in a batch culture form the fatty acid at the end of the exponential phase of growth or in the early stationary growth phase. Previous studies have shown that the biosynthesis and storage of lactobacillic acid in the cell membrane is associated with a protective effect for the bacterial cells, although the exact mechanism has not been conclusively clarified. In bacteriology, the fatty acid is mainly used for analytical purposes, for example in the identification of bacteria.
Sources: en.wikipedia.org
Old Etonian undergraduate Ed Haddon (who had rowed for Isis in 1992) was dropped in favour of German Philipp Schuller. Schuller had arrived at Oxford just two months earlier, but rejected suggestions that his late inclusion was symptomatic of the recent influx of "professionals" to the race. Of his selection, he noted: "You can't have one of the most respected races in the world and then limit it to English people between the ages of 19 and 21 ... on the day we went for whoever would make the boat go fastest. It was done entirely on merit." Schuller's compatriot and opponent Dirk Bangert had struggled with the move to cleavers, finding it difficult to adjust his timing: "I nearly didn't make it. I couldn't get this rhythm until about three weeks ago and was not sure of my place." Oxford's finishing coach was Mike Spracklen who had assisted the Dark Blues in five victorious races, while Cambridge had New Zealander Harry Mahon in charge for the first time, assisted by John Wilson (who had helped coach Oxford to a win in the 1991 race), and Sean Bowden, who was subsequently credited with "being half of the team which first turned Cambridge round". Oxford's head coach Patrick Sweeney noted: "If [Cambridge] get away, they will be hard to beat. If they don't, they're dead meat."
The norepinephrine transporter, or more precisely sodium-dependent norepinephrine transporter (NET), also known as noradrenaline transporter, or more precisely sodium-dependent noradrenaline transporter (NAT), is a protein that in humans is encoded by the solute carrier family 6 member 2 (SLC6A2) gene. NET is a monoamine transporter and is responsible for the sodium-chloride (Na+/Cl−)-dependent reuptake of extracellular norepinephrine (NE), which is also known as noradrenaline. NET can also reuptake extracellular dopamine (DA). The reuptake of these two neurotransmitters is essential in regulating concentrations in the synaptic cleft. NETs, along with the other monoamine transporters, are the targets of many antidepressants and recreational drugs. In addition, altered NET availability is associated with ADHD. There is evidence that single-nucleotide polymorphisms in the NET gene (SLC6A2) may be an underlying factor in some of these disorders.
== Genetics == HCP is caused by mutations in CPOX, which codes for the enzyme coproporphyrinogen oxidase. This enzyme is responsible for the sixth step in the heme biosynthetic pathway, converting coproporphyrinogen III to protoporphyrinogen IX. CPOX is located at 3q11.2-q12.1, has 6 introns and 7 exons and produces an mRNA strand that is 2675 bases in length. It is inherited in an autosomal dominant fashion, meaning that a deficiency of 50% of the normal enzyme activity is enough to cause symptoms. As reproductive fitness is not impacted, homozygous affected individuals have been reported. Along with other acute porphyrias HCP demonstrates reduced penetrance, meaning not all individuals who carry a disease-causing mutation will express symptoms. Individuals who are homozygous for a specific mutation (K404E) or compound heterozygous with a null allele in CPOX have a more severe erythropoietic porphyria, harderoporphyria, characterized by neonatal jaundice, hyperbilirubinemia, hepatosplenomegaly and skin lesions upon exposure to ultraviolet light. HCP is a rare disease, but the exact incidence is difficult to determine due to the reduced penetrance of the acute porphyrias. Overall, the incidence of all porphyrias is estimated at 1:20,000 in the United States. The incidence of harderoporphyria is even lower, with less than 10 cases reported worldwide.
high-throughput Describing a method or system capable of assaying very large numbers of samples or of processing very large quantities of data extremely rapidly, generally by utilizing automation and miniaturization to greatly increase speed and efficiency. For example, high-throughput sequencing refers to modern DNA sequencing technologies that can produce sequence reads for hundreds of millions of DNA fragments simultaneously, allowing scientists to sequence entire genomes quickly and inexpensively.
Sources: en.wikipedia.org
Low temperature slows the chemical reactions, such as oxidation and hydrolysis, that break down a peptide chain. Water and oxygen are the main drivers of degradation, so a cold and dry environment extends usable life. Actual shelf life depends on the batch, the salt form, and the container.
It normally reports the share of the chromatographic signal that belongs to the main peak, not a measure of activity. A high figure means few related substances were detected under the stated method and wavelength. Different laboratories and methods can return different values for the same material.
Retention time alone is weak evidence, because unrelated peptides can elute at similar positions. Amino acid analysis or peptide mapping gives stronger sequence information when a mass spectrometer is unavailable. Most laboratories still treat mass confirmation as the standard step for verifying the correct compound.
The peptide is synthetic, but its sequence matches a segment of a protein present in human gastric juice. It does not occur as a free fifteen-residue peptide in the body.