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We have reviewed here studies of measurement of small concentrations of troponin in patients with myocardial infarction conducted in 2010-2011 which were most significant for the clinic. Troponin is a most specific and sensitive cardiomarker appearance of which in blood serum evidence for a necrotic process in cardiac muscle. We discuss the problem of interpretation of small troponin concentrations by clinicians as well as the states in which appearance of the cardiomarker in blood serum has noncardiac origin. We also discuss novel possibilities of application of troponin as a prognostic marker in patients with stable or unstable angina after revascularization procedures.

Highly sensitive methods for the detection of viral antigens with the use of monoclonal or polyclonal enzyme immunoassay test systems, as well as virus-specific nucleic sequences (NS-gene) in polymerase chain reaction, made it possible to establish the fact of long-term asymptomatic virus carriership (AVC) in some of adolescent schoolchildren in a closed group. The occurrence of AVC varied at different phases of the epidemic process. The tendency to AVC was observed in individuals having blood group B (III) and HLA-A9 antigen of the major histocompatibility complex. The development of AVC occurred in the presence of a decreased level of humoral immunity. AVC was mainly registered among individuals, relatively resistant to relapsing clinically pronounced forms of respiratory virus infections.

The results of many years' studies of HLA-phenotypes in human beings with various susceptibility to influenza infection are presented. Some histocompatibility class I antigens are revealed to correlate moderately with the risk of reinfection and the recurrent course of influenza, as well as with the severity of pulmonary complications and with the inclination of a macroorganism to the latent carriage of viral proteins. The specific features of a humoral immune response to vaccination with attenuated influenza viruses in human beings with HLA-B8 are demonstrated. The authors indicate that there is a trend towards less pronounced manifestations of influenza infection in individuals with antigen-markers A9, B40, characteristic of a Mongoloid population, which might be related to the origin of influenza viruses.

The latent circulation of influenza A virus in nursing home children with congenital central nervous abnormality was studied during 1989-1993 by the present-day diagnostic methods for detection of viral antigens. The influenza A virus antigen detection rates correlated with age, genetic predisposition, prior acute respiratory diseases in mothers during their pregnancy. There is evidence for long-term (up to 17 months) detection of influenza virus antigens in nasal secretions, as well as for prolonged (up to 7 months) detection of the same genomic sequences of HA gene both in leukocytes and nasal washes.

Children with central nervous abnormality were followed up for a long time (180 days). The clinical samples (nasal swabs, blood samples) were investigated for influenza virus antigens or RNA detection by virologic and molecular biological techniques. No viral isolate was found throughout the follow-up. The use of the polymerase chain reaction made it possible to reveal the long-term persistence (for 180 days) of NS- and genes of influenza A (H1N1) viruses in the leukocytes and of HA-gene in the nasal swabs. No NS-gene was found in the nasal swabs. The polymerase chain reaction appears to be more effective for the diagnosis of persistent influenza infection that the conventional techniques--immunofluorescence and enzyme-linked immunosorbent assay (ELISA).

Regular clinical and epidemiological surveys of two groups of healthy 14-16-year-old boys were carried out for 3 years from September 1989 to May 1992 to investigate the latent circulation of influenza A viruses in the human population. Once or twice a quarter clinical materials were laboratorily studied to detect virus antigens, virus-specific NA-sequences and to determine changes in humoral immunity. The latent circulation of influenza A viruses might be identified in 10-20% of cases long before (2-4 months) the onset of epidemic development. The incidence of epidemic isolations was found to reach 33-36%, gradually decreasing from 29 to 9 or 3.5% in the postepidemic period. The long-term persistence (for 5 months) of virus antigens was reported among healthy children who had chiefly blood group B(III). The new hypothesis that the genetic predisposition of children with blood group B(III) to latent persistence of influenza A viruses may be a possible cause of the emergence of new epidemic strains in the South-East Asian countries has been forwarded.

Indices of the functional activity of specific serum antibodies (IFAA) before and after outbreaks of influenza A (H3N2) and B were determined in 164 subjects of 18-20 years of age from the military communities observed in 1987-1988. The IFAA were calculated on the basis of kinetic HI tests followed by computer processing according to the program developed by the authors. The IFAA were found to indicate the protection of human subjects against influenza, reflecting the state of resistance to influenza more exactly than antibody titres. High initial IFAA correlated with lower severity of influenza infection. The IFAA to the same strain may differ significantly in individual subjects. In patients with influenza the time course of antibody titres did not coincide with dynamic changes in IFAA.

In the summer of 1986 the epidemic, whose etiological agents were influenza viruses A (H1N1) and respiratory syncytial virus, was registered among the population of Novoshakhtinsk. In a number of mines 15.3-16.7% of the employees were affected. Influenza viruses A (H1N1) proved to be closely related in their antigenic and biological properties to viruses isolated in the USSR in March-June 1986, as well as to viruses A (H1N1), the etiological agents of the epidemic which developed in the USSR in October-December 1986.

The organization of special hospitals for premature babies contributes to the preservation of their lives. In Kazan, the first such department was opened at the GIDUVA Children's Clinic in 1947 (with 20 beds). The department occupies an isolated room of 3 wards. In the first ward there are 8 closed (glazed) boxes, where new arrivals are accepted, in 2 other wards there are 6 open boxes, to which children are transferred in the future. The department has a reception room where mothers breastfeed their children, a walk-in, an open veranda facing the garden, and a number of necessary utility rooms. The room temperature is maintained within 24-26 . The boxed ward is equipped with electrified beds, which allows them to maintain the proper temperature (up to 28 ). The department also has two incubators of the "Inca" type. Children's underwear is heated in a specially equipped closet. Oxygen is supplied in a moistened form, in the first ward oxygen is supplied to each crib. The boxes are equipped with exhaust ventilation. The compartment is also widely ventilated in the usual way. Quartzization is performed daily.

Clinical and laboratory examinations in two permanently observed children's institutions were carried out in 1968--1978. Altogether, 241 children were examined virologically 759 times, of them 181 children were found to be truly healthy. In the epidemic period the latter yielded virus in 3.7%, in the interepidemic period in 1%. Unlike asymptomatic infection, transitory virus carrier state was not accompanied by antibody production, and in a number of such cases subsequently led to an overt clinical disease.

To study the susceptibility of persons with different blood groups to influenza A, the presence of infection in a group of young children placed under constant observation for 6 years (1974-1980) and in a group of donors observed during 1979-1980 was studied in different epidemic situations. The susceptibility of the persons under observation to type A influenza viruses was shown to depend both on the blood group of the subjects and on the properties of circulating viruses. Persons with group B (III) blood were more susceptible to the virus at the period when new antigenic variants and serotypes appeared, persons with group O (I) blood were more susceptible to influenza infection at the period of the circulation of virulent strains, while persons with group A (II) blood were more susceptible at the period when less virulent strains circulated. The susceptibility of persons with different blood groups was found to change as changes in the properties of the strains occurred in the process of their circulation.

The relationship between the susceptibility of the body to infections caused by influenza A and B viruses, parainfluenza viruses, adenoviruses, Mycoplasma pneumoniae and antigens of the HLA system was studied on a group of 400 adolescents placed under clinico-epidemiological surveillance for two years. The relationship between histocompatibility antigens and acute respiratory diseases was manifested in a decrease or increase in the occurrence of recurrent diseases and infections or in the probability of the development of the diseases in infected persons. HLA B40 was associated with resistance to influenza A, B18 and B21 were associated with resistance to parainfluenza, B15 and B35 were associated with resistance to M. pneumoniae infection; susceptibility to influenza B was registered in persons with HLA B12 and to M. pneumoniae infection, in persons with HLA B16 and B18. With respect to different infective agents, the relative risk of infection varied within 1.7 and 5.0.

Under the conditions of the natural outbreak of influenza B a rise in the level of antibodies in the blood serum and respiratory tract secretions has been found to occur in nonimmunized persons during this disease. Secretory antibodies, along with serum antibodies and in interaction with them, prevent the development of clinically manifest influenza. The asymptomatic form of influenza infection has been revealed: during this form of the disease the response of the body is limited to the local immunity system.

In April-May 1980 a number of unrelated outbreaks of influenza-like diseases were registered in Leningrad in an infant home (50 out of 68 children under observation, aged 3 months to 2 years, were affected) and among the pupils of a boarding school (13 out of 50 adolescents under observation, aged 15-17 years, were affected). 5 strains of influenza A virus were isolated from 3 sick children and 1 clinically healthy child. A similar virus was isolated from a sick adolescent in a boarding school, as well as from a female patient aged 24 years at a domiciliary focus of infection (a sporadic case). In the subsequent laboratory investigation all these 7 strains were identified as viruses A/H2N2. Isolated cases of seroconversion to hemagglutinin H2 were definitely registered in 6 patients during February--May 1980. In 3 cases, including the 24-year old female patient with an acute respiratory disease, seroconversion to hemagglutinin H2 was observed in combination with the release of influenza viruses A/H2N2 from these patients. 2 influenza virus strains with this antigenic characteristic were isolated from a young female patient at an interval of 3 days. Among the patients admitted to the clinics of the Research Institute of Influenza in Leningrad on account of acute respiratory diseases isolated cases of diagnostically significant seroconversion to hemagglutinin H2 constituted 3.5% among children and 4.5% among adults. The study of the level of antihemagglutinins in the population revealed that in 1980 persons aged 18-50 years showed a high level of antihemagglutinins.(ABSTRACT TRUNCATED AT 250 WORDS)

Observations carried out during 1973-1979 indicate that persons, who are frequently ill, determine the incidence of influenza and acute respiratory diseases among various groups of adult population at all epidemic periods. In constantly observed groups of different ages such persons were the source of 60-85% of the outbreaks of acute respiratory diseases. The correlation between genotypic blood markers (the ABO and HLA systems) and susceptibility to respiratory viruses has been established.

Biological properties of 188 strains of respiratory syncytial (RS) virus isolated from 93 institutionalized children during 4 years of observations were correlated with the form and stage of the infectious process, frequency of ARD, and blood group of the children for the evaluation of the epidemiological hazard of sources of RS infection. The degree of virulence of a strain was evaluated by its yields in human embryo lung culture and sensitivity to antibodies (avidity). In clinically manifest forms of RS infection more virulent strains were isolated than in inapparent infections and transitory asymptomatic virus-carrier state. Among the strains derived from children with frequent ARD, highly and moderately virulent strains were prevalent (in 72.7% high and moderate yields in cell culture, and 94.2% low avidity to antibodies) whereas children with rare ARD yielded mainly low virulent strains (70% none or low yields, and 62.5%--highly sensitive to antibodies). The RS virus strains isolated from children with A (II) blood group were found to be less sensitive to antibodies.