If you have been reading about mass spectrometry and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-10-06. Numbers and descriptions here follow the published literature rather than marketing material.
Reconstitution introduces new risks because the peptide contacts solvent, air, and container surfaces. The chosen solvent should match the peptide's solubility profile, and buffer salts, pH, and ionic strength can affect dissolution and subsequent stability. Gentle mixing is preferred over vigorous vortexing, which can create interfaces and shear. If the solution is not clear, the cause may be incomplete dissolution, aggregation, or insoluble counter-ions rather than a simple concentration problem. Filtration is sometimes used, but filters can adsorb peptides and alter measured concentration.
Cold-chain practice relies on documented temperature ranges, calibrated monitoring, and minimized excursions. Shipments may use insulated boxes, phase-change materials, or dry ice, with data loggers to record conditions. Upon receipt, the recipient should verify the logger trace and place items into long-term storage promptly. Repeated warming and cooling during transfers can be more harmful than a single controlled excursion. For solutions, dividing material into single-use aliquots reduces the number of thawing and refreezing events and limits repeated opening of the same container.
Handling begins before a peptide arrives at the bench. Containers should be inspected for cracks, loose caps, or visible moisture, and labels should record identity, lot, and receipt date. Lyophilized material is often allowed to equilibrate to room temperature before opening to prevent condensation on the powder. Gloves and a clean workspace reduce contamination and static-related loss. Once opened, the vial may be purged with inert gas and resealed if the peptide is sensitive to oxygen or humidity. These steps are procedural safeguards rather than guarantees of stability.
Practical handling begins with an inventory record that links each vial to a lot number, synthesis date, and purity certificate. Before opening a container, allow it to equilibrate to room temperature to prevent condensation on the powder. Weighing or transferring should occur in a low-humidity environment using tools that minimize static and adsorption. Hygroscopic peptides may gain water quickly, changing mass and concentration estimates. Recording the container's initial mass and any visible changes supports later reconciliation of material.
Reconstitution introduces additional variables: solvent choice, pH, ionic strength, and filtration. Many sequences dissolve readily in water, while hydrophobic ones may need acetonitrile, dimethyl sulfoxide, or a small amount of base. Adding solvent slowly and avoiding vigorous vortexing can reduce foaming and shear-induced aggregation. If the solution appears cloudy, filtration may remove particulates but can also remove aggregated peptide and alter concentration. A clear solution does not by itself confirm correct sequence or purity, so analytical checks remain necessary.
| Property | Value | Notes |
|---|---|---|
| Container material | Glass or polypropylene | Low-binding options reduce peptide adsorption |
| Typical shipping condition | Dry ice or gel packs | Choice depends on required temperature range |
| Light protection | Amber vial or foil wrap | Reduces photodegradation of sensitive residues |
| Reconstitution solvent | Water, buffer, or organic co-solvent | Depends on peptide solubility and assay requirements |
| Temperature monitoring | Data logger or indicator | Documents excursions during transport and storage |
MALDI-TOF spectra are often used for the identification of microorganisms such as bacteria or fungi. A portion of a colony of the microbe in question is placed onto the sample target and overlaid with matrix. The mass spectra of expressed proteins generated are analyzed by dedicated software and compared with stored profiles for species determination in what is known as biotyping. It offers benefits to other immunological or biochemical procedures and has become a common method for species identification in clinical microbiological laboratories. Benefits of high resolution MALDI-MS performed on a Fourier transform ion cyclotron resonance mass spectrometry (also known as FT-MS) have been demonstrated for typing and subtyping viruses though single ion detection known as proteotyping, with a particular focus on influenza viruses. One main advantage over other microbiological identification methods is its ability to rapidly and reliably identify, at low cost, a wide variety of microorganisms directly from the selective medium used to isolate them. The absence of the need to purify the suspect or "presumptive" colony allows for a much faster turn-around times. For example, it has been demonstrated that MALDI-TOF can be used to detect bacteria directly from blood cultures. Another advantage is the potential to predict antibiotic susceptibility of bacteria. A single mass spectral peak can predict methicillin resistance of Staphylococcus aureus.
== History == Asparagine was first isolated in 1806 in a crystalline form by French chemists Louis Nicolas Vauquelin and Pierre Jean Robiquet (then a young assistant). It was isolated from asparagus juice, in which it is abundant, hence the chosen name. It was the first amino acid to be isolated. Three years later, in 1809, Pierre Jean Robiquet identified a substance from liquorice root with properties which he qualified as very similar to those of asparagine, and which Plisson identified in 1828 as asparagine itself. The determination of asparagine's structure required decades of research. The empirical formula for asparagine was first determined in 1833 by the French chemists Antoine François Boutron Charlard and Théophile-Jules Pelouze; in the same year, the German chemist Justus Liebig provided a more accurate formula. In 1846 the Italian chemist Raffaele Piria treated asparagine with nitrous acid, which removed the molecule's amine (–NH2) groups and transformed asparagine into malic acid. This revealed the molecule's fundamental structure: a chain of four carbon atoms. Piria thought that asparagine was a diamide of malic acid; however, in 1862 the German chemist Hermann Kolbe showed that this surmise was wrong; instead, Kolbe concluded that asparagine was an amide of an amine of succinic acid. In 1886, the Italian chemist Arnaldo Piutti (1857–1928) discovered a mirror image or "enantiomer" of the natural form of asparagine, which shared many of asparagine's properties, but which also differed from it.
Many returning coalition soldiers reported illnesses following their action in the war, a phenomenon known as Gulf War syndrome (GWS) or Gulf War illness (GWI). Common symptoms reported are chronic fatigue, fibromyalgia, and gastrointestinal disorder. There has been widespread speculation and disagreement about the causes of the illness and the possibly related birth defects. Researchers found that infants born to male veterans of the 1991 war had higher rates of two types of heart valve defects. Some children born after the war to Gulf War veterans had a certain kidney defect that was not found in Gulf War veterans' children born before the war. Researchers have said that they did not have enough information to link birth defects with exposure to toxic substances. In 1994, the US Senate Committee on Banking, Housing, and Urban Affairs with Respect to Export Administration published a report entitled, "U.S. Chemical and Biological Warfare-Related Dual Use Exports to Iraq and their Possible Impact on the Health Consequences of the Gulf War". This publication, called the Riegle Report, summarized testimony this committee had received establishing that the U.S. had in the 1980s supplied Saddam Hussein with chemical and biological warfare technology, that Saddam had used such chemical weapons against Iran and his own native Kurds, and possibly against U.S. soldiers as well, plausibly contributing to the GWS. A 2022 study by Robert W. Haley of the University of Texas Southwestern Medical Center, et al., of 1,016 U.S.
Sources: en.wikipedia.org
=== EC 1.1.4 With a disulfide as acceptor === EC 1.1.4.1: Now EC 1.17.4.4, vitamin-K-epoxide reductase (warfarin-sensitive) EC 1.1.4.2: Now EC 1.17.4.5, vitamin-K-epoxide reductase (warfarin-insensitive)
=== Hard fibroma === The hard fibroma (fibroma durum) consists of many fibres and few cells, e.g. in skin it is called dermatofibroma (fibroma simplex or nodulus cutaneous). A special form is the keloid, which derives from hyperplastic growth of scars.
== Signs and symptoms == The symptoms of rhabdomyolysis depend on its severity and whether kidney failure develops. Milder forms may not cause any muscle symptoms, and the diagnosis is based on abnormal blood tests in the context of other problems. More severe rhabdomyolysis is characterized by muscle pain, tenderness, weakness, and swelling of the affected muscles. If the swelling is very rapid, as may happen with a crush injury after someone is released from under heavy collapsed debris, the movement of fluid from the bloodstream into damaged muscle may cause low blood pressure and shock. Other symptoms are nonspecific and result either from the consequences of muscle tissue breakdown or from the condition that originally led to the muscle breakdown. Release of the components of muscle tissue into the bloodstream causes electrolyte disturbances, which can lead to nausea, vomiting, confusion, coma or abnormal heart rate and rhythm. The urine may be dark, often described as "tea-colored", due to the presence of myoglobin. Damage to the kidneys may give rise to decreased or absent urine production, usually 12 to 24 hours after the initial muscle damage. Swelling of damaged muscle occasionally leads to compartment syndrome—compression of surrounding tissues, such as nerves and blood vessels, in the same fascial compartment—leading to the loss of blood supply and damage or loss of function in the part(s) of the body supplied by these structures. Symptoms of this complication include pain or reduced sensation in the affected limb.
The second safeguard clause was a commitment that nothing should be done which might prejudice the rights of the Jewish communities in other countries outside of Palestine. The original drafts of Rothschild, Balfour, and Milner did not include this safeguard, which was drafted together with the preceding safeguard in early October, in order to reflect opposition from influential members of the Anglo-Jewish community. Lord Rothschild took exception to the proviso on the basis that it presupposed the possibility of a danger to non-Zionists, which he denied. The Conjoint Foreign Committee of the Board of Deputies of British Jews and the Anglo-Jewish Association had published a letter in The Times on 24 May 1917 entitled Views of Anglo-Jewry, signed by the two organisations' presidents, David Lindo Alexander and Claude Montefiore, stating their view that: "the establishment of a Jewish nationality in Palestine, founded on this theory of homelessness, must have the effect throughout the world of stamping the Jews as strangers in their native lands, and of undermining their hard-won position as citizens and nationals of these lands." This was followed in late August by Edwin Montagu, an influential anti-Zionist Jew and Secretary of State for India, and the only Jewish member of the British Cabinet, who wrote in a Cabinet memorandum that: "The policy of His Majesty's Government is anti-Semitic in result and will prove a rallying ground for anti-Semites in every country of the world."
Sources: en.wikipedia.org
In the English-speaking world, interpretations of Byzantine history frequently surface in political debates, alongside the growing appreciation for its legacy. The complexity of this history makes it a sensitive topic, especially regarding Greece's role in Europe's evolving sense of identity and the origin stories of many European nations.
Histiocytic diseases in dogs are a group of diseases in dogs which may involve the skin, and which can be difficult to differentiate from granulomatous, reactive inflammatory or lymphoproliferative diseases. The clinical presentation and behaviour as well as response to therapy vary greatly among the syndromes. There are at least four well-defined canine histiocytic diseases:
==== CYP17A1 inhibition ==== Flutamide and hydroxyflutamide have been found in vitro to inhibit CYP17A1 (17α-hydroxylase/17,20-lyase), an enzyme which is required for the biosynthesis of androgens. In accordance, flutamide has been found to slightly but significantly lower androgen levels in GnRH analogue-treated male prostate cancer patients and women with polycystic ovary syndrome. In a directly comparative study of flutamide monotherapy (375 mg once daily) versus bicalutamide monotherapy (80 mg once daily) in Japanese men with prostate cancer, after 24 weeks of treatment flutamide decreased dehydroepiandrosterone (DHEA) levels by about 44% while bicalutamide increased them by about 4%. As such, flutamide is a weak inhibitor of androgen biosynthesis. However, the clinical significance of this action may be limited when flutamide is given without a GnRH analogue to non-castrated men, as the medication markedly elevates testosterone levels into the high normal male range via prevention of AR activation-mediated negative feedback on the hypothalamic–pituitary–gonadal axis in this context.
Sources: en.wikipedia.org
Allow the sealed vial to reach room temperature before opening to reduce condensation. Use a suitable solvent and gentle mixing rather than vigorous agitation. Follow the supplier's solubility information when available.
Aliquots limit repeated thawing and refreezing and repeated vial opening, both of which can promote degradation. They also reduce the chance of contaminating an entire batch. Single-use portions should be labeled with identity, concentration, solvent, and date.
Inspect the package for damage and confirm that temperature indicators or data loggers stayed within the specified range. Check the vial condition and labeling before placing it into storage. Record any excursion or discrepancy for the supplier or quality system.
Work quickly in a dry environment and keep the container closed when not in use. Equilibrate sealed vials to room temperature before opening to reduce condensation. Record mass changes, as absorbed water can affect concentration calculations.