Desensitization

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desensitization

[dē‚sen·sə·tə′zā·shən]
(communications)
Reduction in receiver sensitivity due to the presence of a high-level off-channel signal overloading the radio-frequency amplifier or mixer stages, or causing automatic gain control action.
(immunology)
Loss or reduction of sensitivity to infection or an allergen accomplished by means of frequent, small doses of the antigen. Also known as hyposensitization.
(psychology)
Relief from or removal of a mental complex.

Desensitization

 

(biology), reduction or elimination of increased sensitivity (sensitization) of the organism to repeated introduction of a foreign substance (allergen), most often protein in nature. Upon introduction into the organism of a foreign protein, a specific substance, an antibody, is formed, whose interaction with the protein when it is repeatedly introduced may produce serum sickness or other forms of allergic reactions. Sulfur preparations, aloe, antihistamines, and other antihistamine-antiserotonins possess desensitizing properties.

Desensitization as a method of treating allergic diseases is used, in particular, to prevent serum anaphylaxis from repeated injections of serum preparations (for example, antidiphtheria serum), in accordance with the method proposed in 1907 by the Russian scientist A. M. Bezredka. The method consists in injecting small concentrations of the preparation (the antigen) that produced the sensitization; as a result, a state of antianaphylaxis arises, that is, desensitization. Owing to this, the next injection of the reacting dose of the allergen does not produce anaphylaxis. Allergic diseases (for instance, bronchial asthma and allergic rhinitis) are treated by specific desensitization (if the allergen causing the disease is known), nonspecific desensitization, and complex desensitization. Specific desensitization is especially effective in treating nonbacterial allergies, primarily in pollinoses (hay fever), but it is also successfully used in bacterial sensitization (for example, in treating chronic tonsillitis, tonsillogenic intoxication, and rheumatism). Specific desensitization is performed by intradermal injection of the specific allergen, beginning with a 1:1,000,000 dilution of one cutaneous dose of the specific allergen, and gradually increasing its concentration to 1:10 of one cutaneous dose (the final dilution). If the specific antigen is not found, nonspecific desensitization treatment with antihistamines (for instance, dimedrol, Diprazin, and suprastin), and hormonal preparations are used, (corticosteroid hormones, such as hydrocortisone and prednisolone) as well as physiotherapy and balneotherapy. Complex desensitization, which combines specific and nonspecific desensitizing preparations, is often used.

REFERENCES

Allergiia i allergicheskie zabolevaniia, vols. 1–2. Edited by E. Rajka. Budapest, 1966. (Translated from German.)
Rost, G. A., D. G. R. Findeisen, and I. Niemand-Andersen. Praktikum der allergischen Krankheiten. Leipzig, 1958. Pages 116–31, 196–241.

A. KH. KANCHURIN, P. P. SAKHAROV, and IU. A. FADEEV


Desensitization

 

in photography, a reduction in the light sensitivity of photographic materials under the influence of the substances adsorbed on the halide crystals of the emulsion. Most of the sensitizer dyes and a number of other substances exhibit a desensitizing effect in the range of specific sensitivity for silver halide (λ = 500 millimicrons and lower). Many antifogging agents also act as desensitizers, specifically potassium bromide and some special desensitizers (such as green pinakriptol), which selectively lower the additional sensitivity in the long-wave region. Their inclusion in the developer makes it feasible to begin to develop the sensitized materials in darkness and to end the developing under relatively strong lighting. This sequence affords visual monitoring of the process.