Everything below concerns LC-MS. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-03-03. Where a claim depends on a specific study, the study is described rather than over-claimed.
Commercial NAD+ is available at research grade, often with purity specifications determined by high-performance liquid chromatography. Certificates of analysis may report water content, residual solvents, and counterion identity. Identity can be confirmed by ultraviolet absorbance near 260 nm, mass spectrometry, or enzymatic activity. Because different salt forms and hydration states exist, researchers should verify that the product matches the intended molecular form. Lot-to-lot variation in purity can affect quantitative assays and should be documented.
Solid NAD+ is usually supplied as a white to off-white powder or lyophilized preparation. It is hygroscopic and should be kept desiccated at low temperature, commonly -20 °C or below for long-term storage. Aqueous solutions are less stable than dry material and are often prepared fresh or stored frozen in aliquots. Light exposure and repeated freeze-thaw cycles can promote degradation, so amber containers and single-use aliquots are preferred. Buffered solutions near neutral pH are generally less stable than acidic or frozen preparations.
Research on NAD+ spans biochemistry, aging biology, and metabolism. Studies often examine how NAD+ levels change with age, diet, exercise, or disease states, and whether precursor supplementation alters those levels. Findings in animal models do not automatically translate to humans, and measurement methods vary across studies. Questions about tissue-specific effects, long-term consequences, and causal relationships remain open. NAD+ itself is not established as a single therapeutic agent with a broad clinical role.
Nicotinamide adenine dinucleotide, abbreviated NAD+, is a dinucleotide composed of two nucleotides joined by phosphate groups. One nucleotide contains adenine; the other contains nicotinamide. The molecule exists in oxidized (NAD+) and reduced (NADH) forms, and the reversible hydride transfer between them underlies many metabolic oxidation-reduction reactions. In cells, NAD+ serves as an electron acceptor in pathways such as glycolysis, the citric acid cycle, and oxidative phosphorylation. Its concentration and redox ratio vary by compartment, tissue, and metabolic state.
Beyond redox chemistry, NAD+ is consumed as a substrate by enzymes that transfer ADP-ribose or remove acetyl groups. Sirtuins use NAD+ in deacylation reactions, poly(ADP-ribose) polymerases use it in DNA damage responses, and CD38 hydrolases convert it to signaling metabolites. Because these enzymes compete for the same pool, changes in NAD+ availability can influence multiple cellular processes. The relative contribution of each consumption route differs by cell type and condition, and precise quantitative links remain an active area of study.
| Property | Value | Notes |
|---|---|---|
| Solubility | Freely soluble in water | Forms acidic solution; salt form may alter solubility |
| Typical storage temperature | -20 °C or lower | Desiccated and protected from light |
| Common analytical method | LC-MS | Used for biological quantification |
| UV absorbance maximum | 260 nm | Aqueous solution; pH dependent |
| Common synonym | Diphosphopyridine nucleotide | Older name abbreviated DPN |
Beyond electron transfer, NAD+ serves as a substrate for enzymes that cleave it and attach its ADP-ribose portion to other molecules. This group includes poly(ADP-ribose) polymerases, CD38, and sirtuins. Such reactions consume NAD+ and can influence its availability for metabolism. Cells replenish NAD+ through a salvage pathway that recycles nicotinamide and through routes starting from tryptophan or vitamin B3 forms. How these synthesis and consumption routes are coordinated across tissues remains an active area of study, and compartment-specific concentrations are difficult to measure directly.
Nicotinamide adenine dinucleotide, abbreviated NAD+, is a dinucleotide built from adenine, nicotinamide, two ribose sugars, and two phosphate groups. The oxidized form carries a positive charge on the nicotinamide ring, while the reduced form, NADH, is neutral. This pair acts as a reversible electron carrier in cells. NAD+ is present in bacteria, plants, animals, and fungi. Its structure allows it to accept and donate electrons without being consumed in the reactions it supports.
In redox reactions, NAD+ accepts a hydride ion, which consists of two electrons and one proton. The hydride adds to the nicotinamide ring at a specific carbon, converting NAD+ into NADH. Dehydrogenase enzymes use this step in glycolysis, the citric acid cycle, and fatty acid oxidation. NADH later donates electrons to the mitochondrial electron transport chain, helping to drive ATP synthesis. The balance between NAD+ and NADH reflects the metabolic state of a cell, and shifts in that balance can alter how pathways operate.
Commercial NAD+ is supplied as a solid, often as the free acid or a salt, and purity is verified by chromatographic methods. Laboratories typically store it desiccated at minus 20 degrees Celsius or below. Working solutions are prepared fresh because even sterile aqueous solutions can lose activity over hours to days depending on pH and temperature. Documentation may include a certificate of analysis, an assay value, and a recommended retest date. Researchers should verify identity and purity when results depend on precise cofactor concentrations.
NAD+ is commonly measured by high-performance liquid chromatography with ultraviolet detection, often at 254 or 260 nm. Enzymatic cycling assays provide higher sensitivity by coupling NAD+ to a reporter reaction. Mass spectrometry can distinguish NAD+ from close analogues and confirm isotope labeling. Sample preparation usually involves rapid quenching of metabolism to prevent interconversion with NADH. Because NAD+ and NADH differ by one hydride, extraction conditions strongly affect the measured ratio.
In aqueous solution, NAD+ is most stable under mildly acidic to neutral conditions and degrades faster at high pH or elevated temperature. The molecule can hydrolyze at the pyrophosphate bond or undergo nonenzymatic cyclization. Buffers, chelating agents, and cold temperatures slow these losses during analysis. Repeated freeze-thaw cycles are generally avoided because they can promote degradation and concentration changes. Light exposure is also controlled, though NAD+ is less photolabile than some related nucleotides.
Purified NAD+ is typically supplied as a white to off-white powder and stored desiccated at low temperature. Airtight containers limit moisture uptake, while protection from light reduces degradation of the nicotinamide ring. Aqueous stock solutions are less stable than solid material and are often aliquoted before freezing. Repeated freeze-thaw cycles can lower integrity, so working portions are kept separate. Purity is commonly checked by ultraviolet absorbance near 260 nm, high-performance liquid chromatography, or mass spectrometry.
Stability studies show that NAD+ can hydrolyze under prolonged heat, extreme pH, or microbial contamination. Phosphate buffers near neutral pH are often used for short-term handling, though exact stability depends on concentration, temperature, and matrix. In biological samples, endogenous enzymes can rapidly degrade NAD+, making cold chain and fast processing important. Analytical reports should state extraction conditions, internal standards, and validation parameters. Without those details, comparisons across studies remain difficult and potentially misleading.
Laboratory measurement of NAD+ often begins with rapid quenching of cell or tissue samples to prevent enzymatic conversion. Acidic or alkaline extraction can precipitate proteins, but the chosen method affects recovery of oxidized and reduced forms. Enzymatic cycling assays provide high sensitivity by amplifying a NAD+-dependent reaction. High-performance liquid chromatography and mass spectrometry offer separation and structural confirmation. Each method has trade-offs in throughput, specificity, and the ability to distinguish NAD+ from close analogues.
Seeking to mend ties with the agribusiness sector, the government launched the 2023–2024 Crop Plan, providing R$ 364 billion in rural credit at interest rates below those prevailing in the financial market. This represented a 27% increase in funds compared to the 2022–2023 edition under the previous administration. The "Family Farming Harvest Plan" was also launched, which sought to strengthen family farming by extending rural credit to small and medium landowners, with around R$ 77.7 billion in resources being released for this plan in 2023-2024, a 34% increase in funding compared to the 2022–2023 edition. For the 2024–2025 edition, the government released R$ 400 billion in resources for large landowners, and R$ 85,7 billion for small and medium ones. The 2025–2026 edition released another R$ 516 billion in rural credit for large landowners, and R$ 78,2 billion for family farming. For the 2026–2027 edition, it released R$ 525.1 billion in credit for the agribusiness and another R$ 85 billion for small farms.
==== Style periods ==== A broad classification of styles, formalized by Le Coq and Waldschmidt in 1933, has been generally accepted. The first style is called "Indo-Iranian style I", and cover all the early caves with delicate tone-on-tone paintings, using browns, oranges and greens. The name "Indo-Iranian" broadly denotes the artistic influence from India, combined with elements of Iranian art, that presided over the creation of the first cave paintings at Kizil. The main representative caves of this style are the Cave of the Hippocampi (Cave 118), the Cave of the Painters (Cave 207), the Peacock Cave (Cave 76), the Overpainted Cave (Cave 117), the Cave of the Statues (Cave 77), and the Cave of the Seafarers (Cave 112). The small group of the Treasure Cave (Cave 83, 84) is considered as contemporary, but in a slightly personal style, sometimes called "Special Style" (Sonderstil). The first style is only found in Kizil, except for one cave in nearby Kumtura: the Cave with the cupola. The second style is called "Indo-Iranian style II", and cover most of the other caves of Kizil, which use strongly contrasted colors and strong line strokes, using browns, oranges and greens and especially a vivid lapis-lazuli blue. The name "Indo-Iranian" again broadly denotes the artistic influence from India, combined with important influences from Central Asian and the Iranian world. This style is further divided in three broad periods. Finally, a third Uighur-Chinese style appears in only two caves at Kizil.
The PAH world hypothesis is a speculative hypothesis that proposes that polycyclic aromatic hydrocarbons (PAHs), known to be abundant in the universe, including in comets, and assumed to be abundant in the primordial soup of the early Earth, played a major role in the origin of life by mediating the synthesis of RNA molecules, leading into the RNA world. However, as yet, the hypothesis is untested.
== Preparation and purification == Most isotopes of lawrencium can be produced by bombarding actinide (americium to einsteinium) targets with light ions (from boron to neon). The two most important isotopes, 256Lr and 260Lr, can be respectively produced by bombarding californium-249 with 70 MeV boron-11 ions (producing lawrencium-256 and four neutrons) and by bombarding berkelium-249 with oxygen-18 (producing lawrencium-260, an alpha particle, and three neutrons). The two heaviest and longest-lived known isotopes, 264Lr and 266Lr, can only be produced at much lower yields as decay products of dubnium, whose progenitors are isotopes of moscovium and tennessine. Both 256Lr and 260Lr have half-lives too short to allow a complete chemical purification process. Early experiments with 256Lr therefore used rapid solvent extraction, with the chelating agent thenoyltrifluoroacetone (TTA) dissolved in methyl isobutyl ketone (MIBK) as the organic phase, and with the aqueous phase being buffered acetate solutions. Ions of different charge (+2, +3, or +4) will then extract into the organic phase under different pH ranges, but this method will not separate the trivalent actinides and thus 256Lr must be identified by its emitted 8.24 MeV alpha particles. More recent methods have allowed rapid selective elution with α-HIB to take place in enough time to separate out the longer-lived isotope 260Lr, which can be removed from the catcher foil with 0.05 M hydrochloric acid.
A meta-analysis released subsequently showed that pioglitazone reduced the risk of ischemic cardiac events rather than increased the risk, but increased CHF. A 2020 Cochrane systematic review assessed occurrence of adverse effects with use of pioglitazone, but was not able to reach any conclusions due to insufficient data on included studies.
Sources: en.wikipedia.org
The Forestry Corps can trace its lineage to the Armed Forest Protection Battalions (Chinese: 武装护林大队); There were a total of four battalions; Each of the Hejiang, Songjiang, Longjiang and Jilin provinces consisted of one Armed Forest Protection Battalion. Founded on 25 August 1948, these units were created to conduct counterinsurgency operations against Japanese/Collaborator holdouts (This role was also later expanded to KMT holdouts after the Chinese Civil War), bandits and triads in Northeast China, which would often raid local villages and commit acts of arson, causing wildfires. At the time of establishment, each had 960 soldiers (3840 soldiers, all battalions combined). The Armed Forest Protection Battalions would often disguise themselves as hunters during recon, and used Cavalry tactics. By 16 October 1950, each battalion had 1600 soldiers (6400 Soldiers total). According to archives, by 1952, the Armed Forest Protection Battalions had killed a total of 6 KMT and American spies along with capturing a total of 46 spies, 34 triad members and 71 illegal migrants along with 68 firearms, multiple tens of thousand rounds of ammunition, multiple kilograms of drugs and prevented a total of 7 vandalism incidents. On 11 May 1953, the Armed Forest Protection Battalions were transferred to the People's Economic Police and renamed to the Forest Protection Police (Chinese: 护林警察队). Its task was to patrol forests, prevent illegal entry of protected areas and to serve as lookouts for forest fires.
=== Social organization === A study by Richard H.R. Harper, involving two laboratories, will help elucidate the concept of social organization in laboratories. The main subject of the study revolved around the relationship between the staff of a laboratory (researchers, administrators, receptionists, technicians, etc.) and their Locator. A Locator is an employee of a Laboratory who is in charge of knowing where each member of the laboratory currently is, based on a unique signal emitted from the badge of each staff member. The study describes social relationships among different classes of jobs, such as the relationship between researchers and the Locator. It does not describe the social relationship between employees within a class, such as the relationship between researchers. Through ethnographic studies, one finding is that, among the personnel, each class (researchers, administrators...) has a different degree of entitlement, which varies per laboratory. Entitlement can be both formal or informal (meaning it is not enforced), but each class is aware and conforms to its existence. The degree of entitlement, which is also referred to as a staff's rights, affects social interaction between staff. By looking at the various interactions among staff members, we can determine their social position in the organization. As an example, administrators, in one lab of the study, do not have the right to ask the Locator where the researchers currently are, as they are not entitled to such information. On the other hand, researchers do have access to this type of information.
==== Temperate surface bodies of water ==== A mesophilic start in surface bodies of waters hypothesis has evolved from Darwin's concept of a 'warm little pond' and the Oparin-Haldane hypothesis. Freshwater bodies under temperate climates can accumulate prebiotic materials while providing suitable environmental conditions conducive to simple life forms. The Archaean climate is uncertain. Atmospheric reconstructions from geochemical proxies and models suggest that sufficient greenhouse gases were present to maintain surface temperatures between 0–40 °C. If so, the temperature was suitable for life to begin. Evidence for mesophily from biomolecular studies includes Galtier's G+C nucleotide thermometer. G+C are more abundant in thermophiles due to the added stability of an additional hydrogen bond not present between A+T nucleotides. rRNA sequencing of modern lifeforms shows that LUCA's reconstructed G+C content was likely representative of moderate temperatures. The diversity of thermophiles today could be a product of convergent evolution and horizontal gene transfer rather than an inherited trait from LUCA. The reverse gyrase topoisomerase is found exclusively in thermophiles and hyperthermophiles, as it allows for coiling of DNA. This enzyme requires the complex molecule ATP to function. If an origin of life is hypothesised to involve a simple organism that had not yet evolved a membrane, let alone ATP, this would make the existence of reverse gyrase improbable.
Dupuytren disease is generally considered painless, but can be painful if nerve tissue is involved, although this is not usually discussed in the literature. The most common finger to be affected is the ring finger; the thumb and index finger are much less often affected. The disease begins in the palm and moves towards the fingers, with the metacarpophalangeal (MCP) joints affected before the proximal interphalangeal (PIP) joints. The MCP joints at the base of the finger responds much better to treatment and are usually able to fully extend after treatment. Due to anatomic differences in the ligaments and extensor tendons at the PIP joints, they may have some residual flexion. Proper patient education is necessary to set realistic treatment expectation. In Dupuytren's contracture, the palmar fascia within the hand becomes abnormally thick, which can cause the fingers to curl and can impair finger function. The main function of the palmar fascia is to increase grip strength; thus, over time, Dupuytren's contracture decreases a person's ability to hold objects and use the hand in many different activities. Dupuytren's contracture can also be experienced as embarrassing in social situations and can affect quality of life. People may report pain, aching, and itching with the contractions. Normally, the palmar fascia consists of collagen type I, but in Dupuytren patients, the collagen changes to collagen type III, which is significantly thicker than collagen type I.
The Royal Navy enlisted 184,899 sailors during the Seven Years' War; 133,708 were "lost", either dying of sickness, being discharged as physically unfit or deserting, with scurvy as the leading cause of death. Although sailors and naval surgeons were increasingly convinced that citrus fruits could cure scurvy throughout this period, the classically trained physicians who determined medical policy dismissed this evidence as merely anecdotal, as it did not conform to their theories of disease. Literature championing the cause of citrus juice had no practical impact. The medical theory was based on the assumption that scurvy was a disease of internal putrefaction brought on by faulty digestion caused by the hardships of life at sea and the naval diet. Although successive theorists gave this basic idea different emphases, the remedies they advocated (and which the navy accepted) amounted to little more than the consumption of 'fizzy drinks' to activate the digestive system, the most extreme of which was the regular consumption of 'elixir of vitriol' – sulphuric acid taken with spirits and barley water, and laced with spices. In 1764, a new and similarly inaccurate theory on scurvy appeared. Advocated by Dr David MacBride and Sir John Pringle, Surgeon General of the Army and later President of the Royal Society, this idea was that scurvy was the result of a lack of 'fixed air' in the tissues which could be prevented by drinking infusions of malt and wort whose fermentation within the body would stimulate digestion and restore the missing gases.
Sources: en.wikipedia.org
Bromine (35Br) has two stable isotopes, 79Br and 81Br, with nearly equal natural abundance, and 32 known artificial radioisotopes from 68Br to 101Br, the most stable of which is 77Br, with a half-life of 57.04 hours. This is followed by 82Br at 35.282 hours and 76Br at 16.2 hours; the most stable isomer is 80mBr with the half-life of 4.4205 hours. Like the radioactive isotopes of iodine, radioisotopes of bromine, collectively radiobromine, can be used to label biomolecules for nuclear medicine; for example, the positron emitters 75Br and 76Br can be used for positron emission tomography. Radiobromine has the advantage that organobromides are more stable than analogous organoiodides, and that it is not uptaken by the thyroid like iodine.
== Casualties == In total, Georgia suffered three combat fatalities (all in 2008) and at least 19 servicemen were injured in Iraq. In addition, one Georgian serviceman died in a car accident and one committed suicide, both in 2007.
Evidence of application of poison derived from plants (likely from Boophone disticha) on the tips of 60,000-years-old arrowhead from the Umhlatuzana Rock Shelter (South Africa) is presented by Isaksson, Högberg & Lombard (2026). Arlt (2026) determines the Robberg stone tool tradition in southern Africa to span the internal from 24.800 to 9.700 years ago rather than from 18.000 to 12.000 years ago, and reports evidence of a more gradual transition between Robberg and Oakhurst technocomplexes than indicated by earlier studies. Review of research on the origin and on the course of global spread of Homo sapiens out of Africa from the preceding years is published by Groucutt (2026). Pantoja-Pérez et al. (2026) identify dental and bone abnormalities in the mandible of Qafzeh 25 as likely caused by sharp object trauma, and report evidence of survival of the studied individual after the injury. Litov, Ben-Dor & Barkai (2026) interpret the decline of use of in heavy-duty tools in Levant after the Lower-Middle Paleolithic transition, coinciding with decline of megaherbivores in the studied region, as indicating that the studied tools were primarily used for processing of large prey. Abbas et al. (2026) provide evidence from the study of riverine wetland environments from the Hamra Faddan and Wadi al-Hasa localities from the eastern margin of the Jordan Rift Valley interpreted as indicating that southern Levant provided a stable environmental niche that sustained human populations from the late Middle Paleolithic to the Upper Paleolithic. Zhao et al.
== Vaginal atrophy == In post-menopausal women, the walls of the vagina become thinner (atrophic vaginitis). The mechanism for the age-related condition is not yet clear, though there are theories that the effect is caused by decreases in estrogen levels. This atrophy, occurring concurrently with breast atrophy, is consistent with the homeostatic (normal development) role of atrophy in general, as after menopause the body has no further functional biological need to maintain the reproductive system which it has permanently shut down.
== Biological function == Lipoic acid is a cofactor for five enzymes or classes of enzymes: pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, the glycine cleavage system, branched-chain alpha-keto acid dehydrogenase, and the α-oxo(keto)adipate dehydrogenase. The first two are critical to the citric acid cycle. The GCS regulates glycine concentrations. HDAC1, HDAC2, HDAC3, HDAC6, HDAC8, and HDAC10 are targets of the reduced form (open dithiol) of (R)-lipoic acid.
Sources: en.wikipedia.org
Aqueous NAD+ solutions are best kept frozen in aliquots and protected from light. Repeated freezing and thawing is avoided because it can accelerate breakdown. Dry powder stored desiccated at -20 °C or lower typically remains stable for longer periods.
Liquid chromatography-mass spectrometry provides sensitive and specific quantification in cells and tissues. Enzymatic cycling assays are also widely used for plate-based measurement. Both methods need rapid sample processing to prevent post-collection changes.
Purity refers to the proportion of the intended dinucleotide relative to related nucleotides, salts, and water. A high-purity grade supports reproducible enzymatic assays. Researchers often check purity by chromatographic and spectroscopic methods before use.
NAD+ is a coenzyme found in all living cells. It carries electrons in metabolic reactions and also serves as a substrate for enzymes involved in signaling and DNA repair. Its oxidized and reduced forms are central to energy metabolism.