[Serological and molecular genetic markers of hepatitis C virus in infected donors].

The frequency of hepatitis C virus (HCV) markers was determined in donors; the spectrum and activity of specific antibodies (anti-HCV), the distribution of virus genotypes, and HCV RNA concentrations were studied in virus carrier donors. The activity of antibodies in HCV RNA-negative donors was significantly lower than that in HCV RNA-positive donors (p < or = 0.001). There was a statistically significant difference in antibody activities in donors infected with genotype 1b as compared with those infected with genotype 3a (p < 0.001). However, no correlation was found between the concentration of a virus genome and the activity of specific antibodies. The risk for obtaining infected blood donations was determined during plasma screening by enzyme immunoassay (EIA). Our investigations have indicated that the frequency of serological window period donations is one case per 74750 test plasma units and that of HCV RNA-positive donations with low antibody positivity coefficients, which are frequently detectable as seronegative during screening for laboratory errors, is one case per 37375 test units. A combination of EIA and polymerase chain reaction has shown to minimize the risk of contamination of donor plasma with HCV markers.

[Standardization and the quality control of dental services].

On the base of our experience, it's possible to recommend following methods of controlling of quality of dental aid: daily control of fullness and correctness of filling all the documents by dentist; daily control of quality of restoration installation, fixing of interchannel post and obturation of channel on the base of analyze of roentgenograph; monthly control of precise accomplishment of tooth-treatment methods by dentist; weekly and monthly analyze of comments on filling of documents and accomplishing of treatment methods on medical conferences. The maximum circumstantiation of standarts give an opportunity to calculate the real cost of service and move from cost-sheet principle of keeping up of medical institutes to paying for rendered volume and quality of medical aid.

[Study of physical-chemical properties ot endodontic sealant Acroseal when different methods of root canal obturation].

Results of the study of physical-chemical properties of new endodontic sealant Acrosil (Septodent, France) were presented. The results of all used in the experiment tests corresponded with the existing standards. The received data were compared with the corresponding tests of endodontic sealant AH-Plus (Dentsply, DeTrey, Germany) and were analyzed statistically. The comparison showed higher adhesion properties of Acrosil.

[Neutralization of hepatitis B virus surface antigen with immunoglobulin preparations].

The in vitro experiments with immunoglobulin and blood plasma containing hepatitis B virus (HBV) markers, revealed that the control of immunoglobulin preparations for the presence of hepatitis B virus surface antigen (HBsAg), mandatory for Russia, was not sufficiently informative. The neutralization of HBsAg with specific antibodies to the level, not determined by the EIA method, reached not less than 24 ng/ ml in 2 hours of incubation and not less than 49 ng/ml in 24 hours of incubation, which, when evaluated in 1 lU of anti-HBs, was 34.6 +/- 0.9 ng and 70.7 +/- 1.8 ng of HBsAg respectively. The process of the formation of immune complexes depended mainly on the time of incubation of experimental samples and on the antibody--antigen proportion in the system. The neutralization of viruses by antibodies had no influence on the capacity of the polymerase chain reaction to detect HBV DNA.

[Experimental substantiation of parameters and strength characteristics of new endodontic-endoosseous implant construction].

Postoperative tooth stump is not able to endure usual functional loads adequately that leads to enhanced resorption of bone tissues surrounding root and loss of the tooth. Based on math computer simulation of mode of deformation of biomechanical model "metal-ceramic construction--endodontic-endoosseous implant (EEI)--stump of operated tooth--bone tissue of the jaw" new domestic EEI parameters were elaborated which improved greatly biomechanical properties of tooth with operated roots. Strength characteristics of new EEI were studied. A set of instruments for EEI was developed.

[Test for specific antibodies to virus hepatitis delta based on synthetic peptides]. / Opredelenie spetsificheskikh antitel k virusu gepatita del'ta na osnove sintetitseskikh peptidov.

Solid-phase synthesis of three linear peptides overlapping the major immunodominant epitope of HDAg, which located within amino acid (aa) segment 53-108, and peptide aa 167-179 was carried out. The structure of the peptides corresponded to the sequences of isolates HDV type I. Their antigen reactivity was studied by indirect enzyme immunoassay with sera from patients with hepatitis D and from asymptomatic carriers of anti-delta antibodies. Two B-epitopes located within aa 53-80 and 71-93 appeared to be the most immnunoreactive. The use of these peptides in ELISA allowed anti-delta IGg antibodies to be detected with 95% confidence in serum of patients with hepatitis D and with 87% confidence in serum of asymptomatic carriers of anti-delta antibodies. Analysis of obtained data showed that these peptides can be used in new diagnostic anti-HDV tests.

[Determination of type-specific synthetic peptide antibodies to hepatitis delta virus ]. / Opredelenie tipospetsificheskikh antitel k virusu gepatita del'ta na osnove sinteticheskikh peptidov.

Nine peptides from immunodominant (53-68 and 65-80 aa) and hypervariable (201-213 aa) regions derived from delta antigen sequences corresponding to 3 HDV genotypes were synthesized. Type specificity of antibodies to the resultant peptides was evaluated by indirect enzyme immunoassay with sera from patients with hepatitis D and asymptomatic carriers of anti-delta antibodies. Analysis of the results showed that HDV circulating in the Central Volga region belongs to type I in the majority of cases. High heterogeneity and changeability of HDV genome during the period of transition from acute forms to asymptomatic carriership was revealed. Possibility of circulation of new hybrid HDV strains causing mixed infection in Russia is discussed.

[Diagnostic possibilities of an immunoenzyme test-system for determining the spectrum of antibodies to structural and nonstructural hepatitis C virus antigens]. / Diagnosticheskie vozmozhnosti immunofermentnoi test-sistemy dilia opredeleniia spektra antitela k strukturnym i nestrukturnym antigenam virusa gepatita C.

A new enzyme immunoassay EIA-HCV-Spectr test system constructed on the base of recombinant proteins and synthetic peptides allows separate detection of antibodies to E1/E2, core, HS3, NS4, and NS5 antigens of hepatitis C virus (HCV). The system is highly specific and more sensitive than the test systems used in screening studies, which allows its use as a final test for antiHCV antibodies. Antibodies to various HCV antigens were analyzed using this test system in patients with acute and chronic hepatitis C and asymptomatic donors with antiHCV. In acute hepatitis C during the first-second week after clinical manifestation, antibodies to nonstructural virus proteins are detected 3-4 times less often than in chronic hepatitis C. Acute hepatitis C is characterized by the presence of antibodies only to core antigen (66%). In chronic condition combinations of antibodies to structural and nonstructural HCV antigens predominate: core + NS4, core + NS3 + NS4, core + NS3 + NS5, core + NS4 + NS5, and core + NS3 + NS4 + NS5. In asymptomatic donors with antiHCV and in patients with chronic hepatitis C the spectra of antibodies were similar in 45.7% cases.

Langmuir films from antibodies based on amphiphilic polyelectrolytes.

A technique for forming Langmuir films from antibodies based on an amphiphilic polyelectrolyte was developed. The physicochemical and immunochemical properties of the Langmuir films obtained were studied. The interaction of HBsAg with the films was found to be described by a model with one binding site, whereas that of HBsAg with antibodies adsorbed on a polystyrene plate, by a model with a positive cooperativity. The use of the novel Langmuir films from antibodies increases the sensitivity of the immunoenzyme assay.

[The chromatography of yeast recombinant HBsAg in porous silicas]. / Khromatografiia drozhzhevogo rekombinantnogo HBsAg na poristykh kremnezemakh.

The results of the study of adsorption processes of recombinant HBsAg on various porous silicas are presented. The maximal yield of the recombinant antigen by absorption chromatography was observed on unmodified macroporous glass MPS-2000. A mean yield in this case was 85%. Silica C-80 modified with polyvinylpyrrolidone proved to be most acceptable for gel-penetrating chromatography. The adsorption and gel-penetrating chromatography on porous silicas proved to be an effective method for purification of recombinant HBsAg.

[The danger of hepatitis B virus infection from transfusions of plasma in which the HBs-antigen was detected retrospectively by highly sensitive methods]. / Opasnost' zarazheniia virusom gepatitia B pri perelivaniiakh plazmy, v kotoroi retrospektivno vysokochuvstvitel'nymi metodami vyiavlen HBs-antigen.

The prospective dynamic laboratory and clinical study of premature children was carried out: 55 children who received plasma transfusion during the first weeks of their life and were retrospectively (i. e. after plasma transfusion) found to have HBsAg detected by the passive hemagglutination (PHA) test, the enzyme immunoassay (EIA) and the radioimmunoassay (RIA) and 127 children who received the transfusion of plasma found to be HBsAg-negative according to the results of EIA and RIA. As revealed in this study, the risk of hepatitis B virus infection in such children after the transfusion of plasma containing HBsAg at low concentrations, determined only in the PHA test or in EIA and RIA, was, respectively, 7.5 and 6.3 times greater than in children receiving plasma found to be HBsAg-negative according to the results of EIA and RIA. The results of this investigation showed the tendency towards a decrease not only in the total contamination of plasma recipients with hepatitis B virus, but also in morbidity rate in icteric forms of acute posttransfusion hepatitis B, depending on the concentration of HBsAg in plasma used for transfusion.

[Viral infection markers in foci of chronic hepatitis B]. / Markery virusnoi infektsii v ochagakh khronicheskogo gepatita B.

The intensity of detection and time course of the main markers of virus infection were studied in subjects who had contacts with patients in 74 foci with chronic active hepatitis, 52 with chronic persisting hepatitis and 41 with chronic hepatitis of unknown etiology. A high (up to 80.7%) frequency of detection of HBsAg, anti-HBs, anti-HBc was established in contact subjects which showed a trend of growth with the increase of the time of their contact with the source of infection.

[Patients with chronic viral hepatitis as sources of infection]. / Bol'nye khronicheskim virusnym gepatitom kak istochniki infektsii.

Dynamic observation on 126 foci of infection formed by patients with manifest forms of chronic hepatitis B, 41 foci of chronic hepatitis of unknown etiology, and 37 foci formed by chronic "healthy" carriers was made. In the foci of type 1 the epidemic process developed intensively and was manifested mainly by HBsAg carriership in persons having had contacts with the patients. During the period of observation 43.0% of new cases of infection were detected. In the foci of types 2 and 3 the frequency of contacting infection was not different from that in the control group of the population.

[Binding of the surface antigen of the hepatitis B virus with antibodies studied with different denaturation exposures and with different analytical methods]. / Izuchenie sviazyvaniia poverkhnostnogo antigena virusa gepatita B s antitelami pri razlichnykh denaturiruiushchikh vozdeistviiakh i raznykh metodakh analiza.

The effect of delipidizing agents and a reducing agent on the antigenicity of 20 nm particles of hepatitis B virus surface antigen (HBsAg) was studied. The antigenicity was determined from the capacity of binding with antibody in passive hemagglutination test (PHAT) and dot-blot immune binding (DBIB). Delipidation was found to lead to an apparent decrease of antigenicity caused by aggregation. Subsequent destruction of the aggregates by treatment with sodium dodecylsulphate (SDS) reduced the antigenicity. Treatment with the reducing agent in the presence of SDS results in the loss of antigenicity detectable by PHAT, the DBIB titres remaining unchanged. Some examples demonstrate a high sensitivity of DBIB in detection of HBsAg. The advantages of the latter test over other methods of immune diagnosis are discussed.

[HBe antigen and its antibodies in HBsAg carriers in various regions of the USSR]. / HBe-antigen i antitela k nemu u nositelei HBsAg v razlichnykh raionakh SSSR.

A total of 300 blood serum samples, containing HBsAg and obtained from donors in three regions of the USSR (the RSFSR, the Uzbek SSR and the Moldavian SSR) differing in the level of HBsAg carriership, were studied for the presence of HBeAg and antibodies to this antigen in the passive hemagglutination (PHA) test and in the enzyme immunoassay (EIA). The occurrence of HBeAg was found to depend on the level of HBsAg carriership in the region. Thus, according to the EIA results, in Gorky, Kishinev and Tashkent HBeAg was detected, respectively, in 5.5%, 12.3% and 13.3% of serum samples, the level of HBsAg carriership in these cities being, according to the results of the PHA test, 1.4%, 5.0% and 9.0%. As shown by the results of EIA, the occurrence of HBeAg increased with the rise of the titer of HBsAg, while regarding the occurrence of antibodies to HBeAg the reverse relationship was observed.