FLOCCULATION

From Big Medical Encyclopedia

FLOCCULATION (Latin flocculus a small piece, a fuzz) — the phenomenon of rapprochement and mutual fixing of colloid particles at rather small distances (apprx.

5 microns) from each other leading usually to formation of friable flocculent coagulates — flocculas. Special case F. formation of precipitated calcium superphosphate at reaction antigen — an antibody is (see Antigen — an antibody reaction, Precipitation). In the nature F. under the influence of organic compounds is an important factor of self-cleaning of reservoirs. T. is of great importance for processes of flotation and cleaning of various surfaces of pollution. Phenomenon F. it is used at elimination of water from crude oil (see). Unlike coalescence (see) the separate enlarged particles in a flokkulirovanny state keep independence and are divided by layers of a dispersion medium so between them there are no direct contacts. In foreign literature the term «flocculation» is often used for designation of all types of coagulation (see).

T. in unstable disperse systems (see) occurs when total energy of interaction between particles reaches the so-called secondary minimum caused by a certain equilibration of van-der-vaalsovykh of forces (see the Molecule) forces of electrostatic pushing away at the distances which are not allowing full coagulation. This process is promoted by strengthening of the dispersed substance, temperature increase, and also mechanical, electric and other influences. Most effectively F. causes addition on Wednesday of linear macromolecules — the flocculants bearing polar groups on both ends of a chain (e.g., polyvinyl alcohol). Flocculants are widely used for sedimentation of suspensions and sols, especially at sewage treatment.

For the prevention F. in dispersions pharmaceutical or cosmetics, and also pesticides, etc. apply high concentration macromolecular or surfactants (see Detergents).

Immune flocculation. The Reaction of Immune Flocculation (RIF) represents a special case of reaction of interaction of antigen with an antibody, to-rogo formation of flocculent precipitated calcium superphosphate (flocculas) and opacification of mix results. The REEF it was discovered in 1923 by Ramón during the studying of the mechanism of education and dissociation of a complex diphtheritic toxin — antitoksinony Idiosyncrasy, on a cut use the REEF as one of serological methods of a research is based, the so-called initial flocculation which is that in the mix containing the equivalent, mutually neutralizing each other amounts of antigen and antibodies, formation of a flokkulyat occurs earlier, than in other conditions is. This REEF property is the cornerstone of Ramón's method — quantitative definition of activity of antigens (see) and antibodies (see) in vitro. (A. T. of Glenny) and O7 was entered by Kel (S. of O'Kell) into 1924 Mr. of Glenni a concept of unit of immune flocculation (LI), for to-ruyu it was offered to accept that minimum quantity of toxin or anatoxin, a cut connects 1 ME antidiphtherial serums. In 1928 the first international standard of tetanic antitoxin for the REEF, and in 1935 — the diphtheritic flocculating antitoxin was approved. Thus Ramón's method along with Ehrlich's method entered practice of researches on studying of toxins (see), anatoxins (see) and immune serums (see Serums).

The REEF, as well as other reactions antigen — an antibody, proceeds in two phases. The first phase (an invisible phase) is a specific connection of an antibody with the corresponding antigen; the second phase (a visible phase) — actually flocculation. The first phase REEF proceeds as usual reaction antigen — an antibody. Expressiveness of the second phase REEF is defined by the speed of flocculation and amount of the antigens and antibodies participating in reaction.

Informational content the REEF, as well as any other serological test, depends on strict observance of reference conditions of its carrying out and degree of purity of the antibodies and antigens participating in reaction. The REEF use as an express meto - yes definitions of antigenicity of anatoxins and activity of anti-toxic serums.

Definition of antigenic activity of anatoxins and an antiserum capacity in anti-toxic serums by Ramón's method make as follows. In case of definition of activity of anatoxin in a row of test tubes spill the flocculating serum from 0,1 to 0,3 ml (0,1; 0,12 ml etc.). Bring 1 ml of the examinee of the anatoxin divorced so that the test tube with the expected initial flocculation was in the middle of a row in each test tube. Mixes of anatoxin and serum in test tubes carefully mix and place on the water bath at 40 — 45 °. Test tubes are looked through in 15, 20, 25 min. etc., note a test tube with initial flocculation and time of emergence of initial flocculation (Kf). E.g., initial flocculation happened in a test tube from 0,2 ml of serum. The caption of the used flocculating serum equaled 100 ME/ml, the examinee anatoxin before statement the REEF was divorced by 10 times. The caption of anatoxin is calculated on

a formula T = • and • with

where T — a caption of anatoxin in L17ml, and — a caption of the flocculating serum in ME i of m of l. Kommersant — amount of serum in a test tube with initial flocculation in ml, with — extent of cultivation of anatoxin. Thus, the caption of the examinee of anatoxin (T) is equal in the given example 0,2-100-10 — =200Li/ml. The activity of anatoxins expressed in Lf not always matches the activity defined in animal experiments in reaction anti-current-sinosvyazyvaniya. However at observance of reference conditions of statement the REEF credits tetanic and botulinovy anatoxins

of types A, B, C, determined by Ramón's method, by data A. A. Vorobyova (see t. 29, additional materials),

H. N. Vasilyeva, A. T. Kravchenko, corresponded to the antigenicity defined in animal experiments. Apply the flocculating test anatoxin (toxin) with precisely with a certain content of Lf of 1 ml to definition of a caption of serums. Reaction is put similarly described above, adding the flocculating test anatoxin (toxin) to titrable serum.

The caption of ispytuyemy serum is calculated on a formula

and

where T i — a caption of serum in ME/lsl, T — a caption of test anatoxin in check in Lf 1 of ml, and — the volume of ispytuyemy serum in a test tube with initial flocculation in ml, b — extent of cultivation of serum. E.g., activity of test anatoxin in control appeared equal 18 Li/ml. Initial flocculation came in the test tube containing 0,18 ml of the ispytuyemy serum divorced before statement by 30 times. Thus, the caption of ispytuyemy serum


(Т±) is equal to 4) ~ to PG ~ ~ ^000 to ME/ml. It should be noted that the credits of serums defined with the help the REEF not always match the credits defined in animal experiments. Bibliography: Boyd V. Bases immuno

logiya, the lane with English, page 52, M., 1969; In e y-c of e r Yu. I. and Mintz D. M. High-molecular flocculants in refining processes of water, M., 1975; Vorob

ev A. A. and Voronov 3. And. Studying of some factors influencing reliability of credits of botulinovy and tetanic anatoxins on reaction of flocculation, Zhurn. mikr., epid. and immun., No. 6, page 77, 1962; Sontag G. and

Shtrenge K. Coagulation and stability of disperse systems, the lane with it., L., 1973; Nekrasov B. V. Fundamentals of the general chemistry, t. 1 — 2, M., 1973; F r and d-rikhsberg D. A. Kurs of colloid chemistry, L., 197A; G 1 e and and at And. T. and. O’ To e 1 1 C. C. The titration of diphtheria toxin and antitoxin by flocculation methods, J. Path. Bact., v. 27, p. 187, 1924; Ramon G. Floculation dans im melange neutre de toxine-antitoxine diphteri-que, C. R. Soe. Biol. (Paris), t. 86, p. 661, 1922; it, Sur une technique de tit-rage in vitro du serum antidiphterique, ibid., p. 711; Yomtov M., Solo-mono va K. a. V a 1 with h e v V. A study on the composition of the toxin-antiserum flocculates of two Cl. tetani strains, Z. Imrnun. - Forsch., Bd 132, S. 368, 1967. G. I. Kr lion (immun.),

V. A. Pekkel (biochemical).

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