From Big Medical Encyclopedia

BIOCHEMICAL METHODS OF THE RESEARCH (in diagnosis) — methods of a research of chemical components of biological liquids, cells and fabrics, and also processes of transformation of the substances and energy proceeding in a human body are normal also of pathology. Is of interest for clinical diagnosis: chemical composition of biological liquids and body tissues (pathology can be shown by change of concentration, or lack of one of usual components, or emergence of an unusual component), distribution of liquid and chemical components between various «structures» of an organism and separate cell, processes of transformation of chemical components in the whole organism or its various bodies and their regulation by means of mediators, hormones, fabric hormones, enzymes; processes of exchange of an organism with external environment. The inorganic, organic matters and macromolecules (proteins, nucleic acids) which are a part of live organisms are exposed to a research. The research can be conducted by in vitro in tests of biological liquids (blood, urine, cerebrospinal liquid, notes, digestive juices etc.), pathological liquids (edematous, ascitic, pleural, pericardiac, intra joint etc.) or fabrics, and also expired air, in vivo by means of the sensors (ion-selective electrodes) entered into an organism.

In diagnostic practice the greatest distribution was gained by B. m and. separate chemical components, their connections and ratios between them in tests biol, liquids (blood, urine etc.). Depending on character of a research B. of m and. can be divided on qualitative (detection of required substance in test biol, liquids or fabrics) and quantitative (definition or measurement of its contents). Qualitative methods (see. Analytical chemistry ) are based by the most part on use characteristic of the studied substance of the property which is shown at certain chemical - physical. influence (addition of the corresponding reagent, heating, etc.). The same principle is the cornerstone of direct quantitative methods of a research. However as the structure biol, liquids is quite complex, at quantitative definition of a chemical component usually as the first investigation phase emit from biol, liquids required substance (or group of close substances), and then identify it (on this or that characteristic property) and measure contents (concentration). In some cases division of substances, identification and measurement of concentration can be carried out in one step, napr, at a research biol, liquids by method of gas chromatography (see. Chromatography ). The principles of the chemical, physical and physical and chemical methods applied at biochemical the analysis, are given in tab. 1 and 2.

At a research of enzymes measure by the most part not their concentration, but result of manifestation of their catalytic activity (reduction of content of substrate or increase in content of reaction product, catalyzed by enzyme). A number of the substances possessing high biol, activity, but which are contained in an organism in trace amounts (hormones, mediators) allocate in this or that chemical way, and perform measurement of contents (concentration) with the help biol, test objects (the isolated bodies or the whole organisms of experimental animals) that increases sensitivity and specificity of a research. Recently these biol, methods are forced out by radio immunological.

B.'s improvement m and. it is directed to obtaining the most exact information on a condition of processes of exchange of substance in the whole organism, in a certain body, in a separate cell, in subcellular structures. B. m and. at the same time are combined with methods of immunology, histology, cytology, etc. Such methods are usually difficult, labor-consuming, demand the special equipment.

Other direction of development of B.M. which is not caused by requests of clinical diagnosis is development and use most simplified on technology of performance and the bystry methods allowing to receive within several minutes and even seconds approximate (approximate) assessment certain biochemical, an indicator. B. m and. can be carried out with the help partially or completely mechanized systems, automatic measuring devices, autoanalyzers (see). As release of substance from biol, liquids, and measurement of its concentration can be carried out in various ways. The combinations of these ways representing specific methods of a research are quite numerous. Concerning some substances (cholesterol, cholinesterase) about 100 — 150 options of methods of a research are described. The known specifics of a method of a research can be caused by character investigated biol, liquids depending on concentration of protein, pigments, etc. Along with single researches in diagnosis studying of this or that indicator in dynamics — within a day (assessment of a normal day-night rhythm), under the influence of a certain functional load (identification of the latent defects of metabolism), in development of a disease, under the influence of treatment is of interest. Due to the variety of the biochemical processes which are at the same time proceeding in the course of life activity of an organism combinations of the diagnostic tests reflecting this or that form of pathology, defeat of a certain body, depth or a stage of pathological process in practice are more and more widely applied.

B.'s use m and. in diagnosis imposes special requirements to them: use of the minimum volume biol, material, bystry implementation of the analysis, a possibility of repeated use during the carrying out functional trials, lack of influence to lay down. drugs on results of a research etc. At B.'s assessment m and. it is considered: correctness and reproducibility of results from one definition to another, the accuracy of the received result to the true content of required substance in test, specificity (ability to reveal substance irrespective of presence of other substances) and detection limit (the smallest amount of substance, a cut it is possible to determine by this method).

B.'s variety of m and. gives an opportunity of the choice of the method which is optimum corresponding to tasks and conditions of scientific research. In practical activities of clinical diagnostic laboratories it is more reasonable to use carefully selected unified methods, uniform for all to lay down. - professional, institutions of the country that allows to compare results of the analyses which are carried out to the same patient in different institutions and facilitates logistics of laboratories. Systematic unification of the m which are most often applied in the diagnostic purposes B. is carried out to the USSR and. taking into account scientific medical and economic criteria. The domestic nomenclature of laboratory diagnostic testings contains 150 biochemical, tests.



Bibliography: Asatiani V. S. Biochemical photometry, M., 1957, bibliogr.; it, New methods of biochemical photometry, M., 1965, bibliogr.; Biochemical methods of a research in clinic, under the editorship of A. A. Pokrovsky, M., 1969; Methodical instructions on use of the unified clinical laboratory methods of researches, under the editorship of V. V. Menshikov, M., 1973; Ewing G. V. Tool methods of chemical analysis, the lane with English, M., 1960; Arbeits-methoden der inneren Medizin und ihr verwandter Gebiete, hrsg. v. R. Emmrich, Bd 5, Lfg 1, Jena, 1969; Automation in analytical chemistry, V. a. o., 1972; Henry R. J. Clinical chemistry, N. Y., 1964, bibliogr.; Homolka J. Klinick6 of bio-chemick£ vySetfovaci metody, Praha, 1971, bibliogr.; R e h f e 1 d N. u. R e ίο h e 1 t D. Analytische und praparative Methoden der klinischen Biochemie, B., 1972; R ichterich R. Klinische Chemie, Basel uv a., 1971.

B. B. Menshikov.