Chemical study of cerebrospinal fluid

Major differences in the composition of the cerebrospinal fluid and blood plasma are that, in that the liquid is about 300 times less protein, significantly less cholesterol, Glucose and more chlorides.

Chemical composition of cerebrospinal fluid It reflects major changes, occurring in the central nervous system.

The protein in the cerebrospinal fluid

Normally, in the fluid from the ventricles of the brain contains 0,12-0,2 g / L protein, of cerebellar brain tsisterny- 0.1-0.2, from the subarachnoid space of the spinal cord - a 0.22 0,33 g / l.

Decrease or increase in spinal fluid protein It indicates a pathological process. Average protein content does not give reason to deny the presence of an organic lesion of the central nervous system, because of possible violations of the ratio of protein fractions of cerebrospinal fluid. In normal protein composition differs from the cerebrospinal fluid serum euglobulin absence and presence of additional factions.

The study of the origin of the cerebrospinal fluid proteins found, almost 10 % they have no immunological similarity with serum proteins and are classified as specific proteins CNS.

Increasing the protein content in the CSF It is due to hemodynamic disturbances of the brain and stagnation of blood in the vessels of the central nervous system.

Prealbuminovaya fraction in fluid from the ventricles of the brain is 13-20%, of cerebellar brain tank - 7-13, a fluid, obtained by lumbar puncture,- 4-7 % total protein content. This fraction of the protein is absent in the blockade of cerebrospinal fluid spaces, it may be masked albumin is not always allocated at the highest level of protein in the cerebrospinal fluid.

In brain tumors, and inflammatory diseases of the central nervous system in the cerebrospinal fluid decreases the content of fine fractions (Albumin, A'1- и a2-глобулинов) and increased content of coarse (b- и c-глобулинов).

To identify high content in the cerebrospinal fluid can be used globulins reaction Pandey, based on the turbidity of the liquid due to protein coagulation influenced phenol. Carrying out this reaction drop method allows significant savings test liquid, often delivered to the laboratory in a very small amount.

Globulin response although they are used in the laboratory diagnosis, but give only an approximate idea of ​​the content of protein.

The amount of protein in the cerebrospinal fluid was determined as well, in urine, method Brandberg-Roberts-STOLNIK or colorimetric method using sulfosalicylic acid and sodium sulfate.

The intensity of the turbidity, formed by adding to the cerebrospinal fluid sulfosalicylic acid, proportional to protein concentration.

In hemorrhagic cerebrospinal fluid protein content may be improved by plasma protein. Upon receipt of the cerebrospinal fluid, colored blood, the patient must take the blood from the finger to a tube and isotonic sodium chloride solution to obtain, stained somewhat more intensely, than the liquid. Tubes with cerebrospinal fluid and blood should be the same thickness and color glass. The color of the liquid levels in the comparator, cautiously adding to diluted blood isotonic sodium chloride solution, then it was centrifuged and the amount of protein in a colorless transparent over- sedimentary liquid. True protein in cerebrospinal fluid is obtained by subtracting the amount of protein in the diluted blood from the amount of protein in the liquid haemorrhagic. Methodology This is not very accurate, It is used in cases, When hemorrhagic cerebrospinal fluid becomes colorless after centrifugation.

The protein content of cerebrospinal fluid increases in violation of hemodynamics, inflammatory, after operations on the central nervous system, as well as in tumors of the brain and spinal cord. The marked increase in the amount of protein is observed in venous stasis in conjunction with the violation of the circulation of cerebrospinal fluid. In such cases, high-protein cytosis normal - protein-cell dissociation. In conjunction with the she xanthosis characteristic syndrome Froana, which is observed in tumors of the brain and spinal cord. Reducing the amount of protein in the cerebrospinal fluid is marked at its hypersecretion and hydrocephalus.

Nonne-Apelt reaction dlya specific globulin. Its principle consists in the precipitation of globulins in the presence of saturated ammonium sulfate solution. The reaction is considered positive when the content in the cerebrospinal fluid 0,05 % globulins and more. It gives an indication of the content of globulins in the spinal fluid.

Number globulin significantly increased in chronic inflammatory and degenerative processes in the central nervous system (meningitis, meningoэncefalit, general paralysis, multiple sclerosis). By increasing the level of albumin, globulins broken globulin ratio of cerebrospinal fluid. Normally it varies between 0.2-0.3. For a more accurate picture of the protein fraction of cerebrospinal fluid should define them by electrophoresis or other quantitative methods.

Study of protein composition of cerebrospinal fluid by electrophoresis - A time-consuming process, than the study of the composition of blood serum. In cerebrospinal fluid of 200-400 times less protein, therefore pre-concentrate (concentrated) by ultrafiltration in vacuo, dialysis against dextran or gum arabic, and evaporation in vacuo. However, the thickening of the cerebrospinal fluid may be losing protein fractions or identify artifacts. In connection with this determination has doubtless advantage proteinogram cerebrospinal fluid by electrophoresis on agar gel or of polyacrylamide.

Electrophoresis in agar gel in healthy human cerebrospinal fluid isolated γ₂– и c₃-hlobulynы.

A more sensitive method of protein fractionation of cerebrospinal fluid, it does not require thickening, It is эlektroforez of poliakrilamidnom Gele, allowing to identify the protein fractions 30-40, mainly in the γ-globulin.

The method of immunoelectrophoresis detected in the cerebrospinal fluid immunoglobulin A, M, G, content is 3-4 times lower, than serum: 2,65 mg/L IgG, 2,05 mg / l IgA and 0,24 mg/L IgM.

Fractional composition of cerebrospinal fluid proteins age undergoes major changes. For children is characterized by low levels of albumin, although the level of pre- albumin fraction is relatively high. The elderly observed increase in IgA and IgG, which refer to γ-globulins.

The study of fractional composition of cerebrospinal fluid protein has important diagnostic value, Since a number of diseases of the CNS (tumors, rasseânnom sclerosis) the total amount of it can not be changed. The most diagnostically valuable is the simultaneous determination of protein fractions, lipo- and glycoproteins.

Established, that in acute inflammatory diseases of the nervous system is most characterized by an increase in the content of the cerebrospinal fluid α-globulins, for chronic inflammatory processes - immunoglobulin, and malignant neoplasms - β-lipoprotein.

Colloidal reaction protein determination

Reaction Lange It based on the, that contact pathologically altered cerebrospinal fluid with finely colloidal solution of gold chloride in the presence of electrolytes advancing coagulation and color of the solution changed.

Normally, the cerebrospinal fluid does not change the color of the colloidal solution of gold, He remains red. Change the color of the solution adopted in the pathology to assess figures:

• Red - 0;
• red and purple - 1;
• Violet - 2;
• red and blue or red and opalescent with a small deposition of particles - 3;
• bluish - 4;
• faintly pink color with a bluish tinge, and sediment - 5;
• colorless with sediment - 6.

Distinguish four types of reaction Lange:

• normal, wherein the color change does not occur at all, or three - five tubes color is slightly different from the colors in the control tube (red with a faint purple tinge);
• degenerative, characterized by a change of color in the left half of the number of tubes (from purple to bleaching) and the appearance of the sediment; observed in syphilis of the brain, rasseânnom sclerosis, tumors of the brain and spinal cord, softening of the brain, and others.;
• inflammatory, which tend to change color on the right side or in the middle of the row of tubes; meningitis observed at different ethnology;
• mixed, wherein the color change occurs in the left, and on the right side of the row of tubes; Mixed lesions observed in membranes and brain tissue.

Reaction Takata-Ara completes or confirms the reaction Lange. Based on coagulation proteins cerebrospinal fluid under the influence of mercury dichloride and the solution changes color in the presence of a mixture solution of fuchsin.

There are Four types of reactions:

• negative (normal) - Purple color of the mixture changes, liquid clear;
• degenerative - Loss of blue-purple precipitate, over which there is a clear liquid;
• inflammatory - A mixture of pink color without sediment, time decolorized;
• mixed - Clear liquid over a pink precipitate.

Reaction Takata-Ara is more sensitive, than the reaction Lange.

For the diagnosis of degenerative and inflammatory processes in the CNS used mastic reaction.

Tryptophan reaction and the reaction Levinson are used for the diagnosis of tuberculosis.

Reaction Friedman used for early diagnosis of meningitis. The principle is, that under the influence of potassium permanganate occur redox processes and color changes of cerebrospinal fluid, and under the influence of trichloroacetic acid precipitated protein contained therein. For injuries, tumors, syphilis of the brain, MS color of the liquid does not change.

The cerebrospinal fluid is detected by 20 to 25 free amino acids. To study the amino acid composition of cerebrospinal fluid chromatography using modern methods, ion exchange fluorometry.

The content of free amino acids and the amino nitrogen in the cerebrospinal fluid averaged 0.6- 1,4 mmol / l, below, than in plasma - 1.9-2.8 mmol / l.

An important role in the diagnosis of diseases of the nervous system are studies content in cerebrospinal fluid glucose, enzymes, xloridov, bilirubin, cholesterol and residual nitrogen.

Glucose in the cerebrospinal fluid

Normally, in the cerebrospinal fluid contained 2,5- 3,33 mmol / L glucose. To determine the amount thereof in the cerebrospinal fluid using any of the methods, used to determine the level of glucose in the blood. The liquid is investigated immediately after taking, because it comes quickly glycolysis. In acute and subacute inflammation of the meninges glucose levels in the cerebrospinal fluid decreases, sometimes (which is very rare) it completely disappears. Most often, in the cerebrospinal fluid glucose is absent in streptococcal and meningococcal meningitis.

Increased glucose level is observed in the cerebrospinal fluid and epileptic encephalitis. When tumors of the brain glucose can either grow, and drop.

The lactic acid in the cerebrospinal fluid

In cerebrospinal fluid of healthy humans enzymatic methods determined average 1,54 (0,89-2.8) mmol / L lactic acid.

Most significantly increases the content of lactic acid in cerebrospinal fluid under hypoxic and destructive processes in the brain tissue, that is not only diagnostic, and prognostic value. Enzymes, involved in the metabolism of the CNS, found in cerebrospinal fluid in much smaller numbers, than in blood, and are determined by the same methods, and that in the blood.

Because of the glycolytic enzymes aldolase often defined and lactate dehydrogenase and its isoenzymes.

Chlorides in the cerebrospinal fluid

The chloride content in cerebrospinal fluid normal adult 197-242 mmol / l, in children - 195-204 mmol / l. To determine the level of chlorides in the cerebrospinal fluid can be used by any technique, used to study the blood chlorides, but rather the application of the method of volume determination by titration with silver nitrate liquid.

Decreasing the amount of chlorides observed in tuberculous meningitis, sometimes - with encephalitis, povyshenie- in uremia.

Bilirubin in the cerebrospinal fluid

Bilirubin in the cerebrospinal fluid and fluid from the cysts of the brain is hematogenous origin and causes xanthosis. For the qualitative and quantitative determination of bilirubin uses the same sample, and that for determination of bilirubin in the blood. Normally bilirubin in cerebrospinal fluid are not detected.

Cholesterol in the cerebrospinal fluid

In healthy cholesterol in the cerebrospinal fluid or is absent, or its content ranges from traces to 0.003-0.005 mg / dL. Increased cholesterol levels observed in meningitis and brain tumors, especially malignant.

To determine cholesterol in cerebrospinal fluid can be used Engelhardt-Smirnov method or method of Ilka.

Normally, the residual nitrogen content in the cerebrospinal fluid averaged 8,6-14,3 mmol / l, t. it is. on 50 % below, than in blood.

The level of residual nitrogen in the CSF is investigated by the same methods, and that the content of residual nitrogen in the blood.

Glycoproteins and lipoproteins in the cerebrospinal fluid

The study of glycoproteins and lipoproteins held by electrophoresis on paper in a pre-thickened gel agar or polyacrylamide native or cerebrospinal fluid. These studies are used for diagnosing inflammatory diseases and tumors.

In the cerebrospinal fluid revealed biologically active substances of different chemical nature:

• Mediators (acetylcholine, noradrenaline, dofamin, Serotonin, gamma-aminobutyric acid);
• pituitary hormones, pineal gland and other endocrine glands;
• neuropeptides (endorfiny, enkephalins);
• cyclic nucleotides (adenozincnklofosfat, guanylic acid);
• prostaglandins;
• kinins.

Most of these biologically active compounds is determined by radioimmunoassay, which is increasingly being used in clinical laboratory diagnostics.