UROBILIN

From Big Medical Encyclopedia

UROBILYN (Greek uron wetting + lat. bilis bile) — the general name of group of bilious pigments, end products of disintegration of hemoglobin and other derivative porphyrines in a human body and the highest animals. The term «urobilin» was introduced by Jaffe for the first time (M. Jaffe) in 1868, and in 1907 Mr. Hammarsten (O. of Hammarsten) offered all uro-bilinovy pigments — urobilinigen (chromogen) and their oxidized form urobilin — to call the term «urobilinoida». In a wedge, practice by the term «urobilin» usually designate the bilious pigments removed with urine (see) — products of recovery of bilirubin (see), to-rye more correct to call urobilinoida-m or urobilinovy bodies. Historically developed designations of separate urobilinoid on their excretion with urine — urobilin - and a stake — stercobilin (see) — substantially are not true since these connections can be present at the same time both at urine, and at Calais.

Urobilinoida it is accepted to divide into 3 basic groups. Carry to the 1st group optically inactive / (^-urobilin ((((((((((urobilin I, urobilin 1Xa, mezobilen-b) and its chromogen I (i) - urobilinigen (urobilinigen/, urobilinigen IX and, mezobili-rubinogen). L (1) enter into the 2nd group left-handed - urobilin (urobilin L, stercobilin, tetragidro-mezobilen) and its chromogen of L (1) - urobilinigen (urobilinigen L, stercobilinogen, tetragidromezobilan). Carry dextrorotatory D (d) to the 3rd group - urobilin (urobilin D) and 0 (s1) - urobilinigen (urobilinigen D). Such classification of urobilinoid does not correspond to rules of the chemical nomenclature since proceeding from the names D-and a L-form of urobilinoid shall be isomer-mi-enantiomerami (see the Isomerism), and urobilinoida of I — a racemate of these forms. Actually chemical structure of urobilinoid of different groups is various (fig.) that is necessary learn -

to tyvat for the correct interpretation of results of biochemical analyses.

Urobilinoida represent crystal substances, soluble in ethyl and amyl alcohols and chloroform, partially ether-soluble and the diluted solutions of neutral salts, low solubility in water. From alkaline water solutions of an urobilinoida are besieged to-tami, ammonium sulfate, zinc, lead and phosphatotungstic to - that. Urobilinigens (sometimes they are called by bilana since they do not contain double bonds in the bridges connecting a feast rolled groups in their molecules) are colourless and turn into the corresponding painted urobilins at soft oxidation (e.g., oxidation by oxygen of air). The urobilinigens found in fresh urine and Calais on air are oxidized and turn into the corresponding urobilins of orange-yellow color. Urobilins have specific strips of optical absorption, they are between 485 and 510 nanometers and situation them depends by nature solvent and the size pH. Molecules of urobilinoid are characterized by the «curtailed» spatial structure due to formation of intramolecular hydrogen bindings. Pure urobilinoida differ not only but to sign of rotation of the plane of polarization of light, but also on a nek-eye to chemical properties and staining reactions. E.g., urobilin D gives specific staining reaction with diokeany and salt to - that, to-ruyu do not give urobilins / and L. Urobilin D is less stable, than urobilin L, and we will dissolve in petroleum ether. At oxidation of urobilin / with FeCl2 ferric chloride in salt to - those it is formed mezobiliviolin — connection with intensive violet coloring; substance, similar to it, is found in Calais.

P a redshestvennik at robilinovy pigments is bilirubin, to-ry in the form of conjugates with glucuronic to - that gets as a part of bile into intestines. Apprx. 10% of the bilirubin formed after splitting of these conjugates 8-glyu-kuronidazoy (KF 3. 2. 1. 31), under the influence of intestinal microflora is exposed to recovery and through a number of stages the hl turns. obr. in colourless L-urobilinigen. When bilirubin does not reach intestines (e.g., at obstruction of bilious channels, bilious fistula, the termination of excretion of bile at hepatitis), urobilinoida are not formed. Considerable decrease in formation of urobilinovy pigments happens also in the absence of intestinal microflora (e.g., at a germ-free animal, at the person in the conditions of uncontrolled reception of antibiotics, etc.). A small amount of urobilinoid is soaked up in a large intestine and comes to portal system, is transferred to a liver where it is completely split with formation of dipirrol and trigshrrol. Urobilinoida, getting to urine and causing a normal urobilinuria (see) — to 4 mg/days, are formed, on - vi-dimomu, of the urobilinigen which did not get to portal system and passing thus a liver. Normal process of splitting of urobilinigen in a liver is broken at damage of hepatocytes. In this case urobilinoida get to a big circle of blood circulation and are removed through tyuchka. Thus, the maintenance of urobilinoid in urine is the accessory diagnostic character testimonial of a functional condition of a liver. The increased removal of urobilinoid happens to urine at a row fiziol. states (periods, pregnancy, childbirth, starvation, heavy exercise stresses), and also at the states which are followed by an increased hemolysis (e.g., at hemolitic anemias), a viral hepatitis, acute infections, hron. heart failure, myocardial infarction, hemorrhages, etc. Lack of urobilinoid in urine at hard proceeding jaundice can be connected with toxic dystrophy of a liver. Normal at adults with urine urobilinoida of L are removed, often are found / - forms, is rare — D-forms. Apparently, the way of formation of D-urobilinigen in normal conditions is collateral and becomes more active at suppression by antibiotics of intestinal microflora. A small amount of the urobilinigens which did not collapse in a liver gets to bile. The maintenance of urobilinoid in bile makes less than 1% of the content in it of bilirubin and increases at hemolitic diseases and progressing of an acute hepatitis. In bile the hl is found. obr. L-urobilinigen and only traces of D-urobilinigen.


Fig. Constitutional formulas of urobilinoid: I \urobilinigen I (mezobiliru-

binogen); II \urobilin I; III \urobilinigen L (stercobilinogen); IV \urobilin L (stercobilin); V \urobilinigen D; VI \urobilin D. Symbols: M — methyl group (— CH3); E — ethyl group (— CH2 — CH3); R — and r about p and l n and I am group (— (' N 2 — CH 2 — With ’About IT); V \vinyl group (— SN — CH2).


Normal concentration of urobilinoid in blood is small (to 30 mkg / 100 ml), but it increases at hepatitis, cirrhosis, hemolitic anemias, etc.

With a stake the main quantity of the urobilinoid (50 — 250 mg/days) which are formed in intestines, hl is distinguished. obr. L-urobilinigen (see. With terkobilin). In nek-ry cases (e.g., at hemolysis) also urobilinigen/, and after the termination of treatment by antibiotics — urobilinigen D is found. The increased removal of urobilinoid with a stake is observed at periods, pregnancy, in the first days after the delivery and at the diseases which are followed by hemolysis (to 3000 mg/days), and decrease — at disturbance of passability of bilious channels.

Usually at a wedge, researches make determination of total quantity of urobilinoid, but not separate pigments of this group. Most often make qualitative test of urobilinoid in urine and Calais. The methods of definition of urobilinoid based on reaction with are eurysynusic? dimethylaminobenzaldehyde (a reactant, or aldehyde, Ehrlich), to-ruyu all pirrola with free hydrogen atom in a-situation give. As a result of reaction connections of red color are formed. Definition of urobilinoid in urine is carried out with fresh samples of urine. To 1 ml of urine at the room temperature add 1 drop of a reactant of Ehrlich — 2 g of 7g-dimethyl-minobenzaldegida to 100 ml of 20% of solution salt to - you (Neybauer's test). If coloring develops after 30 sec. of standing, test is considered normal, to 30 sec. — positive (the increased maintenance of urobilinoid); in case of lack of coloring at long standing test is also considered normal or pointing out lack of urobilinoid in urine. Bogomolov's test (see Bogomolov test) consists in coloring of chloroformic extract of urine in red color after addition to fresh urine of saturated copper sulfate and salt to - you. Florans's test is made usually with the purpose to reveal lack of urobilin in x \yuche and consists in extraction by sulphuric ether of the urine acidified by a chamois to - that, with the subsequent lamination of radio extract on salt to - that. Emergence of a pink ring on the phase boundary demonstrates

presence of urobilinoid. Detection of urobilinoid of urine by means of Schlesinger's reactant (spirit suspension of zinc acetate) is based that zinc acetate, interacting with urobilinoida, gives green fluorescence. This reaction demands careful extraction and purification of material since not only urobilinoida can fluoresce. Nentsky's test — Ziber is also based on emergence of green fluorescence as a result of interaction of the urobilinoid extracted by isoamyl alcohol with zinc chloride. For unmixing of urobilinoid use methods of column chromatography (see), paper chromatographies, an electrophoresis (see), etc.

Definition of urobilinoid in Calais — see. With terkobilin.

Bibliography: F. I. mosquitoes, To

a ditch to and B. F. N and M e N sh ii-ii: about in V. V. Biochemical researches in clinic, L., 1981; The Guide

to clinical laboratory diagnosis, under the editorship of M. A. Bazarnova, p.1, page 56, Kiev, 1981; Todo ditch Y. Clinical laboratory trials in pediatrics, the lane with bolg., Sofia, 1968;

Whyte A. and d river. Fundamentals of biochemistry, the lane with English, t. 3, M., 1981; T. K.'s With Bile pigments, Chemical, biological and clinical aspects, N. Y. — L., 1968.

H. V. Gulyaeva.

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