NAD+/NADH ratio is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-02-12. Where a claim depends on a specific study, the study is described rather than over-claimed.
NAD+ is the oxidized form of nicotinamide adenine dinucleotide, a coenzyme built from two nucleotides joined by a phosphate linkage. One nucleotide carries adenine, and the other carries nicotinamide; the plus sign denotes a formal positive charge on the nicotinamide ring, not a free proton. In cells, NAD+ and its reduced partner NADH form a reversible redox pair. That pair participates in electron transfer reactions throughout metabolism. The abbreviation NAD+ is common in biochemistry, while NAD(H) sometimes denotes the combined pool.
The molecule was first described in the early twentieth century as a factor that promoted fermentation in yeast extracts. Later work linked it to hydrogen transfer and to the oxidation of nutrients in living tissues. Its structure was resolved as a dinucleotide, which explained why it could accept and donate electrons at specific enzyme sites. Today, NAD+ is recognized as a central substrate and signaling precursor, not merely a metabolic cofactor. Whether all observed NAD+ changes reflect causal signaling remains an open question.
Related compounds include NADH, the reduced form, and NADP+, which carries an additional phosphate group. NADP+ and NADPH often serve in biosynthetic and antioxidant reactions, while NAD+ and NADH are more associated with energy-yielding catabolism. Nicotinamide, nicotinic acid, and nicotinamide riboside are precursors that can enter salvage pathways. The exact contribution of dietary precursors to tissue NAD+ pools is an area of active investigation. Some studies measure labeled precursors to trace those routes.
Measuring NAD+ in biological samples requires rapid processing because the compound can degrade or interconvert after collection. Common approaches include enzymatic cycling assays, high-performance liquid chromatography, and mass spectrometry. Each method has different sensitivity, specificity, and susceptibility to interference from related nucleotides. Sample type matters: cultured cells, animal tissues, and human blood present distinct challenges. Reported values can vary widely across laboratories because of differences in extraction, normalization, and analytical platform. Standardization remains an open issue in the field.
NAD+ is relatively unstable in aqueous solution, especially at neutral or alkaline pH and at elevated temperatures. It is typically stored dry, protected from light and moisture, and kept cold or frozen for long-term use. Solutions are often prepared fresh or buffered to mildly acidic pH to slow hydrolysis. Repeated freeze-thaw cycles can reduce integrity. Laboratories may verify concentration using ultraviolet absorbance at 259 nm or by enzymatic assay. These handling practices are general laboratory conventions rather than universal rules.
Research on NAD+ often examines changes with age, diet, exercise, and disease states, but causal relationships are difficult to establish. Some studies measure NAD+ levels, while others assess enzyme activity or downstream markers. In the literature, terms such as "NAD+ decline" and "NAD+ boosting" appear in both scientific and commercial contexts, sometimes without precise definitions. Whether changes in measured NAD+ directly produce health effects remains an open question. Results from cells, animals, and humans cannot be assumed to translate directly.
| Property | Value | Notes |
|---|---|---|
| Chemical name | Nicotinamide adenine dinucleotide (oxidized form) | NAD+ denotes the oxidized redox state |
| Common synonyms | Diphosphopyridine nucleotide; coenzyme I | Older names appear in historical literature |
| Molar mass | About 663.43 g/mol | Free acid value; salts and hydrates differ |
| Appearance | White to off-white powder | The purified solid is white; solutions are clear |
| Solubility | Highly soluble in water | Aqueous buffers are common laboratory solvents |
Beyond redox chemistry, NAD+ acts as a substrate for several enzyme families. ADP-ribosyltransferases, sirtuins, and CD38 ectoenzymes cleave the molecule into nicotinamide and ADP-ribose or related products. These reactions connect NAD+ availability to processes such as DNA repair, chromatin modification, and calcium signaling. Because the coenzyme is used in both electron transfer and signaling, cells maintain separate pools in compartments including the cytosol, mitochondria, and nucleus. The relative sizes and regulation of those pools remain active areas of study.
Cells produce NAD+ through several biosynthetic routes. The salvage pathway recycles nicotinamide, while the Preiss-Handler pathway uses nicotinic acid, and a de novo route can start from tryptophan in some organisms. In mammals, the salvage pathway is generally considered the main source under ordinary conditions. Tissue concentrations vary widely by cell type and compartment, and measured declines with age have been reported in some studies. Whether such changes drive aging or mainly accompany it remains an open question.
Beyond redox chemistry, NAD+ serves as a substrate for enzymes that cleave the molecule and transfer its ADP-ribose moiety or remove acetyl groups. Sirtuins consume NAD+ during deacetylation, poly(ADP-ribose) polymerases use it in DNA damage responses, and CD38 enzymes hydrolyze it to signaling metabolites. These consumption pathways mean that NAD+ availability can influence gene regulation, DNA repair, and calcium signaling. Cellular NAD+ concentrations decline in some tissues with age in animal models, but whether this decline is a cause or consequence of aging in humans remains an active open question.
Nicotinamide adenine dinucleotide, commonly abbreviated NAD+, is a dinucleotide coenzyme built from an adenine nucleotide and a nicotinamide nucleotide joined by a pyrophosphate linkage. Its oxidized form carries a positive charge on the nicotinamide ring, while the reduced form, NADH, carries a hydride equivalent. The molecule participates in hundreds of oxidoreductase reactions, where it accepts or donates electrons and protons. Because it can cycle between oxidized and reduced states without net consumption, NAD+ functions as a reusable electron carrier rather than a fuel molecule.
In glycolysis, the tricarboxylic acid cycle, and fatty acid oxidation, NAD+ is reduced to NADH at specific dehydrogenase steps. NADH then delivers electrons to the mitochondrial electron transport chain, mainly at complex I, supporting oxidative phosphorylation and ATP production. The balance between NAD+ and NADH, often expressed as a ratio, influences metabolic flux and redox homeostasis in different cellular compartments. Cytosolic and mitochondrial pools are connected but not identical, and their ratios can differ substantially because of compartment-specific enzymes and transport systems.
Narrated by Paul Brightwell, produced by David Sington, directed by David McNab, made by Dox Productions 4 March The Engines That Came in from the Cold, about the Russian N1 rocket with an unexpected and surprising outcome to the documentary, and a reference to the 1963 book The Spy Who Came in from the Cold; George Mueller, head of Apollo programme from 1963 to 1969; Charles Vick of the Federation of American Scientists; Sergei Korolev, chief designer at OKB-1; Vasily Mishin, deputy chief designer at OKB-1, had done calculations showing that to get a cosmonaut on the Moon, it required a 100 tonne vehicle in orbit, which would require a 2,000 tonne vehicle at lift-off; Valentin Anisimov, chief designer at Kuznetsov Design Bureau, and how Korolev approached the Kuznetsov company, to make the new rocket engines for the proposed N1 rocket launcher, but it was too new and large to develop from scratch, so thirty pre-existing engines would be deployed, and the pre-burner which powered the rocket pumps would become a closed cycle, to improve power by 25%, but this was vastly untested; the first twelve launches would be uncrewed, followed by two test crewed launches, and the Soviet limited budget meant that development was not at a sufficient stage (that NASA would have arrived at) before the launches were carried out; this first uncrewed launch took place on 21 February 1969, and one minute into the flight, the rocket exploded; the N1 had a thrust of 4,500 tonnes at launch; the N1 second launch took place on 3 July 1969, after the engine control system was modified, and a few seconds after launch the engine cut out, and the whole N1 launcher fell onto the launch pad, causing total catastrophic results - this explosion stopped any further Soviet Union attempt to reach the Moon with a crewed rocket, the launch pad damage was unrecoverable; two weeks later Apollo 11 landed on the Moon; the N1 next launch was on 26 June 1971, with a rebuilt launch pad, and this launch exploded one minute into the flight; the fourth launch of the N1 on 23 November 1972 exploded two minutes into the flight; by the mid-1970s the Kuznetsov NK-33 closed-cycle engine, for the N1, had been sufficiently tested in its development lifetime; the Soviet Moon mission was around four years behind NASA, and when the engines were finally sufficiently tested, the whole Soviet Moon programme was stopped in 1974; any N1 engines and systems were instructed to be removed, to eliminate its knowledge; only in the early 1990s did knowledge of the N1 first appear; Bob Ford of Lockheed Martin and Bill Hoffman of Aerojet; Kuznetsov had nonetheless kept around sixty NK-33 engines in Samara - the home of Soviet rocketry, and wanted to show these engines to visitors from Aerojet; after a successful test of an NK-33 at Sacramento in October 1995, the NK-33 was developed into the RD-180, which powered the American Lockheed Martin Atlas III rocket; John Karas, of Lockheed Martin, at the first launch of an American rocket, on 24 May 2000 of the Eutelsat 36A satellite, that was powered by a Russian engine - the RD-180, which was twice as powerful as the NK-33, and one engine could replace five engines of the previous Atlas II; Vladimir Chvanov and Boris Katorgin, designers at NPO Energomash; the American rocket engineers had viewed the closed-cycle method as far too dangerous, and it was dangerous, but Russian engineers had developed new stainless steel alloys to largely overcome this danger. Narrated by Jaye Griffiths, produced by Hamish Barbour, directed by, made by Ideal World Productions 17 June The Day the Oceans Boiled, about the Earth's environment; 55 million years ago, the Earth was 6C hotter than it is now, with no ice caps, and trees grew at Antarctica, the temperature became 8C hotter, known as the Paleocene-Eocene Thermal Maximum; mammals shrunk in how large; since 55m years ago, carbon dioxide has been absorbed by plants, cooling the Earth; climate models were derived from weather forecast models; Peter Cox (climatologist) of the Met Office, and carbon sinks, and how each year 6 billion tonnes of carbon dioxide enters the atmosphere, but the effect appears to be only from around 3 billion tonnes; Antonio Nobre of the National Institute of Amazonian Research - he found that the Amazon forest, and its 500 million hectares of trees, was a much bigger carbon sink than presumed - it could be absorbing three-quarters of the carbon dioxide of all the world's vehicles; the Greenland Ice Sheet Project, and Geoffrey Hargreaves at the National Science Foundation Ice Core Facility (NICL) in Colorado, and ice cores from the Vostok Station; the Earth has warmed and cooled in a 100,000 years cycle; the Met Office model predicted that after 2050, due to shortage of rainfall seasons, the Amazon forest would not act as a carbon sink; Carlos Nobre (scientist) and dry seasons, and the possible danger of fire, caused by changes in the tropical climate; Richard Corfield (scientist); Philip D. Gingerich of the University of Michigan; Santo Bains was researching the Paleocene-Eocene boundary, so went to the Gulf Coast Repository, and looked at Core 690 drilled by JOIDES Resolution of the Ocean Drilling Program from the Weddell Sea, and concluded that rapid changes in Earth temperature came from methane clathrates (methane hydrates); geologist Euan Nisbet; the Earth returned to lower temperatures after 60,000 years. Narrated by Matthew Zajac, directed by David Sington, made by Dox Productions 24 June The Fish That Time Forgot, about the coelacanth; Margery Courtney Latimer in 1938 of the Natural History Museum, London, and a fish caught at East London; J. L. B. Smith, from Grahamstown, of Rhodes University; the American Museum of Natural History; evolutionary biologist John McCusker; the Comoro Islands, run by the French, near Madagascar, where another fish was found in 1952; Mike Ruton; Robin Stobbs; the JAGO (German research submersible) and Hans Fricke of the Max Planck Institute for Behavioral Physiology, who found a live fish on 17 January 1987; Susan Jewett of the National Museum of Natural History in Washington; on 30 July 1998, a live female fish is found on a beach in Indonesia by Mark Erdmann. Narrated by Robert Lindsay, produced by Ron Ackerman, directed by Celia Lowenstein, made by Diverse Productions with Nova 8 July The Secret Life of the Mouse, about the laboratory mouse; zoologist Sam Berry of UCL; mouse geneticist Jo Peters of MRC Harwell; Irving Weissman; most genetic research is done with mice, with 25 million a year; Steve Brown, Director of MRC Harwell; the mouse has 99.9% of the genes of humans; the Jackson Laboratory has 1m mice and around 1,000 human staff, with 2,500 strains of mice, who have mouse models of human diseases, and mice breed much quicker than humans do; Beverly Paigen; in one year, there are three generations of mice; twenty Nobel prizes have depended on mouse research; Cliffe Rosen of the Maine Center of Osteoporosis Research; scientists want mutant mice for each gene; Charles Vacanti of the University of Massachusetts Medical School, whose cartilage research led to a mouse having an artificial cartilage human ear grown on its back; Philip Leder of Harvard Medical School, who placed a patent on a mouse; a fluorescent mouse; Hank Greely of Stanford University; it ends with the opening lines from A Tale of Two Cities. Narrated by Stephen Fry, produced by David Paterson, directed by Kevin Hull, made by BOA 2001. The documentary has overtones of the music video of the 2001 Where's Your Head At, made in the same year as the documentary 15 July Saving the Leaning Tower, a documentary chronicling the dramatic rescue of one of the world’s most iconic landmarks. By the late 1980s, the Leaning Tower of Pisa was on the brink of collapse, its southward tilt increasing steadily and threatening catastrophic failure. Alarm spread after the sudden fall of a medieval bell tower in Pavia in 1989, which convinced authorities to close Pisa’s monument to the public. An international committee of engineers, geologists, and historians was formed to save the tower, among them British civil engineer John Burland. Through detailed investigation, the team uncovered the structural weaknesses behind the marble façade and the unstable soils beneath Pisa. Computer models showed the tower should already have collapsed. Temporary steel tendons and 600 tonnes of lead counterweights prevented immediate disaster, but the tower’s fate remained uncertain. Burland proposed a novel, delicate solution: controlled “soil extraction” below the northern side to allow the tower to gently tilt back to stability. The project was plagued by risks, political disputes, and near-disasters, including the “Black September” of 1995, when freezing the foundations caused the tower to lurch alarmingly. Despite opposition, the soil extraction method was eventually approved in 1998. Over two years, engineers removed around 70 tonnes of soil, gradually reducing the lean by half a meter without visible alteration to the monument. By June 2001, the tower had been successfully stabilized, restored to the inclination it had in the 18th century, and reopened to the public. The operation was hailed as one of the greatest feats of modern civil engineering, ensuring the survival of Pisa’s unique heritage for centuries to come. The documentary presents not only the technical challenges but also the cultural, historical, and emotional significance of preserving this medieval masterpiece. 13 October Battle of the Robots: The Hunt for AI, about the work of Hugo de Garis, Rodney Brooks, and Steve Grand (roboticist); the documentary opens with the archetypal and iconic robot HAL 9000 from the 1968 2001: A Space Odyssey (film) and The Blue Danube; Igor Aleksander, who worked in neural systems at Imperial College London, and his views on the likelihood of computational intelligence; Dan Dennett; British roboticist Steve Grand, of North Somerset made the world's first AI computer game Creatures in 1996, and was designing a glider that could teach itself; Blay Whitby of the University of Sussex; the MIT Computer Science and Artificial Intelligence Laboratory and Brian Scassellati, who was designing a social robot called Cog (project); Belgian Walter De Brouwer of Starlab in Belgium; engineer Kevin Warwick of the University of Reading at the 2001 Royal Society Prizes for Science Books (Aventis Prize for Science Books), won by Robert Kunzig. Narrated by Patrick Forbes, produced by Nicolas Kent 28 October Bioterror, an Equinox Special, about biological weapons, with Judith Miller and her 2001 book Germs: Biological Weapons and America's Secret War; Robert Kadlec of the National War College; science writer William Broad; the ATCC in Manassas, Virginia; microbiologist William C. Patrick III; the 2001 anthrax attacks; microbiologist Richard O. Spertzel; geneticist Matthew Meselson; Gennady Lepyoshkin, Director from 1987 to 2001 of a Russian secret biological research site; Jonathan B. Tucker; Chris Shays; Andrew C. Weber; Sergei Popov (bioweaponeer) had worked at the State Research Center for Applied Microbiology in Obolensk, Moscow Oblast. Produced by Matthew Collins, directed by Kirk Wolfinger, made by WGBH. Shown on Tuesday 20 November 2001 on The Nature of Things in Canada, and on Nova, and on Nova on Tuesday 13 November 2001
== Biosynthesis == Proline is biosynthetically derived from the amino acid L-glutamate. Glutamate-5-semialdehyde is first formed by glutamate 5-kinase (ATP-dependent) and glutamate-5-semialdehyde dehydrogenase (which requires NADH or NADPH). This can then either spontaneously cyclize to form 1-pyrroline-5-carboxylic acid, which is reduced to proline by pyrroline-5-carboxylate reductase (using NADH or NADPH), or turned into ornithine by ornithine aminotransferase, followed by cyclisation by ornithine cyclodeaminase to form proline.
Obsessive–compulsive disorder (OCD), which happens to be its only US FDATooltip Food and Drug Administration-labeled indication. Other regulatory agencies (such as the TGA of Australia and the MHRA of the UK) have also approved clomipramine for this indication. A 2024 systematic review found that clomipramine is also effective in managing OCD in pediatric population. Major depressive disorder (MDD), a popular off-label use in the US. It is approved by the Australian TGA and the United Kingdom MHRA for this indication. In Japan it is also approved for depression. Some have suggested the possible superior efficacy of clomipramine compared to other antidepressants in the treatment of MDD, especially the more severe, although at the current time the evidence may be insufficient to more fully substantiate this claim. As-with other tricyclic antidepressants, the antidepressant response specifically may be augmented, including in treatment-resistant cases, with triiodothyronine, at a dosage of 50 mcg. In the case of clomipramine specifically, this may also be the case with OCD.
Sources: en.wikipedia.org
=== Transvaal stayaway: 5–6 November 1984 === On 27 October, at a meeting of 37 political, civic, and labour organisations in Johannesburg, COSAS reiterated a prior call for workers to support the youth's demands and oppose the heavy-handed state response to the uprising. The meeting resolved to form an ad hoc joint committee, the Transvaal Regional Stay-Away Committee, which would coordinate a two-day stay-away. In a major development, trade unions – notably the largest union, the Federation of South African Trade Unions, but also the Council of Mining Unions and the Metal and Allied Workers' Union – overcame their prevailing tendency towards to political "absenteeism" and participated. The stay-away, held on 5 to 6 November, was a resounding success. On competing estimates, between 40 per cent and 60 per cent of workers in Johannesburg did not attend work on the first day, and the government said that 250,000 students had not attended school. On the second day, the figures were even higher, including an estimated 90 per cent of workers in Vaal, 85 per cent on the East Rand, and 66 per cent in Soweto. That evening, Sasol, the state-owned energy corporation, announced that it had fired 90 per cent of its workforce – 6,000 workers – for participating. The work-stoppage was accompanied in some areas by further violence and arson, met by police tear gas and rubber bullets; ten people were reported killed on the first day and a further seven on the second.
== Diagnosis == Dwarfism is often diagnosed in childhood on the basis of visible symptoms. A physical examination can usually suffice to diagnose certain types of dwarfism, but genetic testing and diagnostic imaging may be used to determine the exact condition. In a person's youth, growth charts that track height can be used to diagnose subtle forms of dwarfism that have no other striking physical characteristics. Short stature or stunted growth during youth is usually what brings the condition to medical attention. Skeletal dysplasia is usually suspected because of obvious physical features (e.g., unusual configuration of face or shape of skull), because of an obviously affected parent, or because body measurements (arm span, upper to lower segment ratio) indicate disproportion. Bone X-rays are often key to diagnosing a specific skeletal dysplasia, but are not the sole diagnostic tool. Most children with suspected skeletal dysplasias are referred to a genetics clinic for diagnostic confirmation and genetic counseling. Since about the year 2000, genetic tests for some of the specific disorders have become available. During an initial medical evaluation of shortness, the absence of disproportion and other clues listed above usually indicates causes other than bone dysplasias.
At low enough temperatures, a distinction can be made between the axial and equatorial hydrogens in cyclohexane. An example of nuclear magnetic resonance being used in the determination of a structure is that of buckminsterfullerene (often called "buckyballs", composition C60). This now famous form of carbon has 60 carbon atoms forming a sphere. The carbon atoms are all in identical environments and so should see the same internal H field. Unfortunately, buckminsterfullerene contains no hydrogen and so 13C nuclear magnetic resonance has to be used. 13C spectra require longer acquisition times since carbon-13 is not the common isotope of carbon (unlike hydrogen, where 1H is the common isotope). However, in 1990 the spectrum was obtained by R. Taylor and co-workers at the University of Sussex and was found to contain a single peak, confirming the unusual structure of buckminsterfullerene.
In analogy to other aziridines, N-methylaziridine can be obtained by a Wenker synthesis from N-methylaminoethanol. This is done either via the sulfuric acid ester or after replacement of the hydroxy group by a chlorine atom (for example by thionyl chloride or chlorosulfuric acid) to N-methyl-2-chloroethylamine and then by using a strong base (cleavage of HCl) in an intramolecular nucleophilic substitution:
Sources: en.wikipedia.org
=== Dinosaurs === It has been theorized that the neural spines of Spinosaurus, Ouranosaurus, and other dinosaurs with similar spines had humps, rather than the sailfins they are commonly depicted as having. If true, such humps would aid with heat regulation, storing of lipids for egg production, and storing fat for long migrations. Concavenator corcovatus is named for its hump (the name means "hunchback hunter from Cuenca"), but its use is debated, with theories including heat regulartion, attracting mates, intimidating rivals, or fat storage.
Several studies have determined the potential use of PCSK9 inhibitors in the treatment of hyperlipoproteinemia (commonly called hypercholesterolemia). Furthermore, loss-of-function mutations in the PCSK9 gene result in lower levels of LDL and protection against cardiovascular disease. Drugs can inhibit PCSK9, leading to lowered circulating LDL particle concentrations. Since LDL particle concentrations are thought by many experts to be a driver of cardiovascular disease like heart attacks, it is plausible that these drugs may also reduce the risk of such diseases. Clinical studies, including phase III clinical trials, are now underway to describe the effect of PCSK9 inhibition on cardiovascular disease, and the safety and efficacy profile of the drugs. Among those inhibitors under development in December 2013 were the antibodies alirocumab, evolocumab, 1D05-IgG2 (Merck), RG-7652 and LY3015014, as well as the RNAi therapeutic inclisiran. PCSK9 inhibitors are promising therapeutics for the treatment of people who exhibit statin intolerance, or as a way to bypass frequent dosage of statins for higher LDL concentration reduction. A review published in 2015 concluded that these agents, when used in patients with high LDL-particle concentrations (thus at greatly elevated risk for cardiovascular disease) seem to be safe and effective at reducing all-cause mortality, cardiovascular mortality, and heart attacks.
Haüy postulated, "to each specific substance with a well defined chemical composition, capable of existence in a crystalline form, there corresponds a shape that is specific and characteristic of that substance." In 1808 John Dalton published his atomic theory of matter. In Dalton's theory, there were four key assertions: "matter is made up of roughly spherical atoms, which were indivisible and indestructible; all atoms of a given element are identical in mass and properties; compounds are formed by a combination of two or more different kinds of atoms; and chemical reactions involve the rearrangement of atoms". In his book A New System of Chemical Philosophy, crystals are considered as a periodic arrangement of spherical atoms. However, Dalton stated that it was premature to form any theory of crystallization. Kuhn proposed Dalton's atomic theory as an example of a paradigm in which Dalton asserted that atoms can only combine in simple, whole-number ratios (law of multiple proportions). Under this new paradigm, any reaction which did not occur in fixed proportion could not be a chemical process. There was a contradiction between the crystallographic and chemical paradigms. Haüy's theory asserted that crystals were composed of polyhedral units stacked up in three dimensions without gaps; Dalton's theory, by contrast, implied that crystals were constructed by a periodic arrangement of spherical atoms in space.
=== 7 April === An Iraqi national, identified as Abbas Abuthar Witwit, died in a hospital in Luhansk due to injuries sustained while fighting as a member of the Wagner Group in Bakhmut the previous day, in what is believed to be the first confirmed case of a Middle East native to have died fighting in the war. His death was confirmed by Wagner's head Yevgeny Prigozhin, who said he had been recruited from a Russian jail, on 1 June.
== Partial EMT or a hybrid E/M phenotype == Not all cells undergo a complete EMT, i.e. losing their cell-cell adhesion and gaining solitary migration characteristics. Instead, most cells undergo partial EMT, a state in which they retain some epithelial traits such as cell-cell adhesion or apico-basal polarity, and gain migratory traits, thus cells in this hybrid epithelial/mesenchymal (E/M) phenotype are endowed with special properties such as collective cell migration. Single-cell tracking contributes to enabling the visualization of morphological transitions during EMT, the discernment of cell migration phenotypes, and the correlation of the heritability of these traits among sister cells. Two mathematical models have been proposed, attempting to explain the emergence of this hybrid E/M phenotype, and its highly likely that different cell lines adopt different hybrid state(s), as shown by experiments in MCF10A, HMLE and H1975 cell lines. Although a hybrid E/M state has been referred to as 'metastable' or transient, recent experiments in H1975 cells suggest that this state can be stably maintained by cells.
Sources: en.wikipedia.org
It indicates a formal positive charge on the nicotinamide ring. The molecule is not simply a protonated acid, and the charge is part of its redox chemistry.
NAD+ is the oxidized form, while NADH is the reduced form carrying two additional electrons and a proton. The two forms interconvert in many metabolic reactions.
No. NADP+ contains an extra phosphate group on the adenine ribose. NADP+ and NADPH tend to participate in different biosynthetic and antioxidant pathways.
Researchers often use enzymatic cycling assays, liquid chromatography, or mass spectrometry. The choice depends on sample size, sensitivity needs, and available equipment. Because NAD+ can degrade quickly, rapid extraction and careful handling are important.