niacin

Niacin is also known as niacin or anti-roughness factor. It is rich in niacin in liver, lean meat, poultry, peanuts and yeast. The content of niacin and tryptophan in various cereals is low. Niacin is transaminated to form nicotinamide, and nicotinamide reacts with phosphoribosyl pyrophosphate to form nicotinamide mononucleotide, which combines with ATP to form nico-tinamide adenine dinucleotide (NAD), also known as Coenzyme I (CoI). NAD binds to adenosine triphosphate (ATP) to form nicotinamide adenine dinucleotide phosphate (NADP), also known as coenzyme II (CoII). In many anaerobic dehydrogenases, NAD and NADP act as dehydrogenases. Both NAD and NADP are the main coenzymes of the redox reaction system in cellular metabolism. In addition to the food source, niacin can also be converted from tryptophan, which begins with kynurenine. Requires tryptophan pyridase and formylase, which hydrolyzes the formyl kynurenine to kynurenine, and then 1-choline urate hydrolase decomposes kynuric acid or xanthoic acid to 3-hydroxyaminobenzoic acid, and then Under the action of 5-phosphoribosyl pyrophosphate, the enzyme system of the mammalian liver becomes niacin. The products of niacin after metabolism are N'-methylnicotinamide and N'-methyl-2-pyridone-5-carboxamide. The former is 20% to 30% of the excretion in the urine, and the latter is in the urine. 40% to 60% of the amount of excretion. Basic Information Specialist classification: growth and development check classification: urine / kidney function test Applicable gender: whether men and women apply fasting: not fasting Analysis results: Below normal: Niacin deficiency. Normal value: N\'-methylnicotinamide: 3.0-37.0mg Above normal: No clinical significance. negative: Positive: Tips: Determine the amount of nicotinic acid metabolite N\\\'-methylnicotinamide in 24h urine. Normal value The reference value of two metabolites in normal load test is 7.0～37.0mg, and when it is <3.0mg, it is niacin deficiency in vivo. Clinical significance Nicotinic acid deficiency (also known as pella-gra). The main clinical manifestations are bilateral symmetry dermatitis, organic psychosis, encephalopathy syndrome and digestive system syndrome (such as scarlet glossitis, tongue stripping and stomatitis). One of the main symptoms of niacin deficiency is gastrointestinal symptoms such as stomatitis, glossitis, diarrhea and dyspepsia. Iron and folic acid deficiency can occur over time, so there are various types of clinical (small cell hypochromic, Normal cell or large cell) anemia. In addition, when niacin is deficient, skin keratin supplementation is insufficient, and dehydrogenation coenzyme catalyzes the oxidation of cysteine ​​to form glutathione, which is a sulfhydryl matrix enzyme having an activity of inhibiting tyrosinase in the epidermis. Tyrosinase catalyzes the formation of melanin in the skin by tyrosine. Therefore, when niacin is lacking, the skin pigment is excessively produced, and once the friction or sunlight is irradiated, the skin rash and dermatitis symptoms are present. Low results may be diseases: niacin deficiency in children, niacin deficiency neurological precautions Laboratory tests can only be used under conditions, and determination of niacin in blood is unreliable. So far, the amount of N'-methylnicotinamide excretion of niacin in 24h urine (calculated per gram of creatinine) has been determined, which is currently considered to be the most effective test for determining the nutritional status of niacin in vivo. Clinical symptoms have declined before they appear and have clinical value. Inspection process 1. Purify and take 2 ml 10 ml stoppered test tubes, indicating the measuring tube (U) and standard tube (S). 2 ml of urine and 0.2 ml of glacial acetic acid were added to the tube, and diluted to 10 ml with water. A standard solution of 10 ml of N'methylnicotinamide was added to the standard tube. Add 100 mg of activated carbon to each of the two tubes, mix them several times, immediately filter with filter paper, and take the filtrate for determination. 2. Take 10 tubes with 10 ml stoppers, indicate the measuring tube (U), measure the blank tube (UB), standard tube (S) and standard blank tube (SB), and follow the steps. 3, the fluorescence measurement first with the quinine sulfate application liquid to read the reading to 50 ~ 80. The excitation wavelength is 330-360 nm, the emission wavelength is 430-450 nm, and the fluorescence intensity of each tube is read. Not suitable for the crowd Menstrual women. Adverse reactions and risks no.