KETONE BODIES

From Big Medical Encyclopedia

KETONE BODIES (synonym acetone bodies) — group of the organic compounds which are intermediate products of exchange of fats, carbohydrates and proteins. Emergence of the increased quantities To. t. in blood and urine is the important diagnostic character testimonial of disturbance carbohydrate and a lipometabolism.

K K. t. belong beta and hydroxy-butyric to - that (see. Hydroxy-butyric acids ), acetoacetic acid (see) and acetone (see); they have a similar structure and are capable to interconversions:

Exchange

Synthesis To. t. (ketogenesis) occurs hl. obr. in a liver in three ways: 1) condensation under action thiomanholes (atsetoatsetil-KOA — thiomanholes; KF 2.3.1.9) two molecules atsetil-KOA, formed at beta oxidation of the highest fatty acids (see), or at oxidizing decarboxylation (see) pyruvic acid (see), edges it can be formed in the course of exchange glucose (see) and a number of amino acids (see. Tricarboxylic acids cycle ); 2) as a result of synthesis acetoacetic to - you from atsetoatsetil-KOA, formed directly of four last carbon atoms remaining at consecutive oxidation fat to - t with a long carbon chain; 3) as a result of education acetoacetic to - you as an intermediate product at oxidation of so-called ketogenic amino acids leucine (see), tyrosine (see), phenylalanine (see) and to a lesser extent isoleucine (see).

In the main way of synthesis To. t. the first since this way more others depends on character of food is considered and more suffers at patol, disbolism.

From a liver To. t. come to blood and then to all other bodies and fabrics (muscles, kidneys, lungs, etc.)» where join in a cycle Tricarboxylic to - t, in Krom are oxidized to carbonic acid and water. To. t. are used for synthesis cholesterol (see), the highest fat to - t, phosphatides (see) and replaceable amino acids (see).

At the increased contents To. t. in blood (see. Acetonemia ) they are brought by kidneys (see. Acetonuria ), and also lungs in the form of acetone with expired air. The most considerable giperketonemiya is observed at diabetic (ketoatsidotichesky) to a coma (see).

At starvation (see), unilateral bezuglevodisty food and at insufficient secretion of insulin (see. diabetes mellitus ) use atsetil-KOA in a cycle Tricarboxylic to - t and in synthesis fat to - t (through malonil-KOA) is suppressed as all metabolic available resources of an organism turn into glucose of blood. In these conditions atsetil-KOA goes mainly for education oksimetilglutaril-KOA that leads to increase in synthesis To. t. At reception to food of ketogenic amino acids, some proteins and a large amount of fats (or the strengthened mobilization of fat from fat depos) there is an intensive education atsetoatsetil-KOA and To. t. The ketogenic effect of alkaline salts is caused by activation of transformation oxalacetic to - you (oxaloacetate) in asparagine and alpha ketoglutarate in a glutamate that leads to disturbance of functioning of a cycle Tricarboxylic to - t. Introduction with food of carbohydrates leads to the strengthened education oxalacetic to - you, edges is condensed with atsetil-KOA and slows down education To. t. Insulin stimulates synthesis fat to - t from atsetil-KOA and activates use of the last in a cycle Tricarboxylic to - t therefore intensity of synthesis decreases To. t.

At the healthy adult blood serum contains 0,2 — 2,5 mg of % To. t. (in terms of acetone), in erythrocytes concentration To. t. it is less; with urine 20 — 54 mg are allocated per day To. t. Such concentration To. t. cannot be determined by the usual methods used in clinic.

Ketonemiya and ketonuria are observed at a diabetes mellitus (the ketogenesis is raised and it is reduced ketoliz), carbohydrate starvation, fevers, the general starvation and exhaustion (the ketogenesis is raised), reception of food rich with ketogenic substances (the ketogenesis is strengthened), at reception of significant amounts of alkaline agents, at postoperative states, glycogenoses I, II and VI types (it is broken ketoliz), a hyper dysinsulinism, a thyrotoxicosis, the expressed glucosurias, an acromegalia, hyperproduction of glycocorticoids (a shortcoming, the strengthened expense or loss of carbohydrates), infectious diseases (scarlet fever, flu, tubercular meningitis, etc.) and intoxications (e.g., at lead poisoning), etc. Are a consequence of a ketonemiya not respiration acidosis (see) and acetonic poisoning (acetone dissolves structural lipids of cells), at which transport of glucose through biol is broken, membranes and is sharply oppressed activity of c. N of page

Methods of definition

For definition To. t. a large number of various methods and tests based on the reactions specific either for acetone or for acetoacetic to - you is offered.

Basic groups of methods use the reactions specific to acetone, napr, formation of a complex of acetone with bisulphite, connection with iodine, sedimentation by mercurous cyanide, sedimentation by mercurous sulfate, reactions with salitsilaldegidy, dinitrophenylhydrazine, vanillin, au nitropetrolaldehyde and furfural, and also the reactions specific for acetoacetic to - you: reactions with Sodium nitroprussidum, ferric chloride, Resorcinolum, n-amidoacetophenone. A basis of a large number of methods of quantitative definition To. t. in blood and in urine reaction with salicylic aldehyde is.

Natelson's method (S. Natelson, 1961). The acetone which is forced out from blood or from urine konts. a chamois to - that, forms with salicylic aldehyde in alkaline condition connection of red color. Intensity of coloring is measured photometric. Acetoacetic to - that is previously turned into acetone heating at 60 ° in acid medium. In internal space of a cup of Conway (see. Conway methods ) pour 2 ml of 2% of solution of sodium bisulphite, and in external space — 1 ml of the whole blood mixed with sodium fluoride for prevention of coagulation and 0,5 ml of 10% of solution a chamois to - you. The cup is immediately densely closed a cover, carefully shaken to mix blood with a chamois to - that, and put in the thermostat at 60 ° for 1 hour. During this time acetoacetic to - that turns into acetone which diffuses in internal space of a cup of Conway where connects to sodium bisulphite; 1,5 ml of contents of internal space transfer to a test tube, add 1,5 ml of 40% of solution of caustic soda and 0,3 ml of 20% (about.) solution of salicylic aldehyde in absolute alcohol. Mix, put for 20 min. in the thermostat at 50 °, then for 30 min. at the room temperature and kolorimetrirut at 540 nanometers against check. Check, in to-ruyu instead of blood 1 ml of water bring, and process the standard solution containing 2 mg of % of acetone the same as pilot test. Calculate the content of acetone proceeding from the size of an extinction of standard solution on a formula:

(extinction of pilot test • 2) / extinction of the standard = mg of % of acetone.

At the same time to define and beta and hydroxy-butyric to - that, i.e. the sum of all To. t., it is necessary to oxidize it to acetoacetic to - you, and then to acetone.

For this purpose 3 ml of a filtrate of blood serum after sedimentation of protein tungsten to - that place in external space of a cup of Conway and add 0,5 ml of 10% a chamois to - you and 0,5 ml of 5% of potassium bichromate or sodium. Further definition is carried out as it is described above.

In customary practice for detection To. t. apply generally qualitative tests. They are used by hl. obr. for a research of urine. Advantage of these a coffin is that they allow quickly, though approximately, to reveal patol, increase in concentration To. t.; at normal contents To. t. these tests are negative. The greatest application was found by nitroprussiate tests which are specific hl. obr. for acetoacetic to - you are also based on reaction To. t. with Sodium nitroprussidum in alkaline condition with formation of the connection painted in red color. Similar connections form also some amines, napr, creatinine; however in acid medium amine complexes break up also the coloring caused by creatinine disappears, and coloring of ketonic complexes remains. On this principle it is based Legal's test (E. Legal, 1883): to 4 ml of urine add several drops of freshly cooked 5% of solution of Sodium nitroprussidum and 0,5 — 1 ml of 10 — 15% of caustic soda; red coloring is formed. Add for acidulation 0,5 — 1 ml konts. acetic to - you; at negative test coloring disappears — creatinine complexes break up, at positive — remains, and an impression of decolourization since color of creatinine complexes brown-red, and ketonic — cerise is made. Test Roterums (A. S. N of Rothera, 1908) — the most sensitive of nitroprussiate tests. Roterum noted that creatinine prevents reaction if for alkalifying use caustic soda, but use of ammonia eliminates these hindrances. In a test tube pour 5 — 8 ml of urine and saturate it with dry ammonium sulfate, add 2 — 3 drops konts. ammonia and 5 drops of freshly cooked 5% of solution of Sodium nitroprussidum, stir up; at a positive take dark red or violet coloring is formed. There is a micromodification of nitroprussiate test Roterums, for carrying out the cut is required only several drops of urine with semi-quantitative assessment of results in of dependence on intensity of coloring [Fri and Fri (A. N. of Free, H. M of Free), 1958].

From nitroprussiate tests it is widely applied also Lange's test (Page F. A. Lange, 1906): to several ml of urine add several drops of freshly cooked 10% of solution of Sodium nitroprussidum and 0,5 — 1 ml konts. acetic to - you, carefully layer several ml konts. solution of ammonia. Test is positive if within 3 min. on border of liquids the pink-violet ring is formed.

On reaction acetoacetic to - you with ferric chloride are based Gerhardt's test (S. A. S. J. Gerhardt, 1865). Test usually is considered as insufficiently sensitive: with its help it is possible to find about 25 — 50 mg of % acetoacetic to - you (nitroprussiate tests catch usually 5 — 10 mg of %). Solution of ferric chloride (10%) is flowed on drops to several milliliters of urine until the deposit of ferrous phosphate which is filtered ceases to be formed; add some more drops of solution of ferric chloride to a filtrate. At positive test fioletovokrasny coloring is formed. Salicylates also give positive reaction therefore to exclude the coloring caused by salicylates carry out repeated definition with the urine which is warmed up within 5 min. in the boiling water bath; acetoacetic to - that during the heating breaks up, and coloring disappears; salicylates give positive reaction and after warming up.

The reactions specific for beta and hydroxy-butyric to - you, it is not described. Applied to definition beta and hydroxy-butyric to - you Gardt's test assumes preliminary oxidation beta and hydroxy-butyric to - you by means of hydrogen peroxide in acetoacetic and further definition with Sodium nitroprussidum: 20 ml of urine mix from 20 ml of a distilled water, acidify several drops 20% acetic to - you, boil until volume decreases to 10 ml, bring to 20 ml water and spill equally in two test tubes. Add 1 ml of 30% of solution of hydrogen peroxide to one and heat within 1 min. in the boiling water bath. To both tests add 10 drops ice acetic to - you and on 10 drops of the solution of Sodium nitroprussidum sated in the cold, stir, carefully layer 25% solution of ammonia. In the presence of beta and hydroxy-butyric to - you in a test tube, in to-ruyu were added hydrogen peroxide, the cerise ring appears.

For express definitions To. t. the special tablets consisting of mix of dry reactants and paper strips, impregnirovanny reactants which part Sodium nitroprussidum is are issued. After immersion of such strip (or tablets) in the studied liquid (urine or a blood plasma) in case of positive reaction violet coloring, intensity is formed to-rogo compare to a standard color scale.

See also Lipometabolism , Carbohydrate metabolism .


Bibliography: Biochemical methods of a research in clinic, under the editorship of A. A. Pokrovsky, page 276, M., 1969; Leyte from S. M. and Laptev N. N. Sketches on a pathophysiology of a metabolism and endocrine system, M., 1967; Lenindzher A. Biochemistry, the lane with English, M., 1976; Nyos-holm E. istart To. Regulation of metabolism, the lane with English, page 355, M., 1977; Todorov Y. Clinical laboratory trials in pediatrics, the lane with bolg., Sofia, 1968; Clinical chemistry, principles and technics, ed by R. J. Henry a. o., N. Y. a. o., 1974.

V. K. Gorodetsky; L. M. Pimenova (met.issl.).

Яндекс.Метрика