Specific modification of free lysine amino groups of histidine decarboxylase from Micrococcus sp. n. by trinitrobenzene sulfonic acid]

It has been found that 14 lysine residues are accessible for trinitrobenzene sulfonic acid (TNBS) in the molecule of histidine decarboxylase (HDC). The other 62 lysine residues in the molecule of native HDC are masked and inaccessible for TNBS. It is demonstrated that the SH- and alpha-amino groups of methionine are not modified by TNBS. A correlation between the decarboxylase activity of the enzyme and the degree of its trinitrophenylation has been studied. HDC, whose molecule contains 3--9 TNP groups, retains up to 90--97% of its initial activity. Trinitrophenylation of 14 lysine residues induces inactivation of HDC by 33--34%, which probably depends on conformational changes or steric hindrances, occurring in the catalytic site of the modified active centre of HDC. Using circular dichroism and fluorescence methods as well as disc-electrophoresis in polyacrylamide gel, it has been shown that trinitrophenylation does not cause any significant changes in the enzyme structure. The TNP groups have been found to be localized in the large and small subunits of the HDC molecule.     

Evaluation of the role of specific antimeningococcal antibodies in the spread of meningococcal carrier states in collectives]

The results of serological, bacteriological and epidemiological studies carried out in populations with different epidemic pattern of meningococcal infection are presented. A-group specific antibody was found to have the leading role in the intensity of the spread of meningococcal infection in the populations. The presence of antibody to this antigen in 16.7% of serum samples inhibited dissemination of meningococci in the populations. Simultaneously with an increase in the herd immunity level to 34.8% the attenuation of the active meningococcal dissemination cycle was observed. Meningococci isolated in the populations with different epidemic patterns of meningococcal infection were shown to have different ecological properties.     

Measures to prevent outbreaks of hospital infections

On the basis of the analysis of 69 outbreaks of hospital infections registered in the USSR in 1986-1989, as well as additional observations made by the authors, a number of factors which determined the present state of the problems concerning this kind of morbidity in the USSR were established: an insufficient level (in cases of enteric infections) or a low level (in cases of purulent septic infections) of etiological diagnosis; poor efficiency of the epidemiological investigation of outbreaks; defects in the work on the prophylactic detection of potential sources of infection among medical staff, parturient women or mothers taking care of their infants. Some possible solutions on these aspects were proposed. Cases of outbreaks of hospital infections among newborns were used as an example demonstrating that such outbreaks were caused mainly by breaches of antiepidemic and sanitary rules in respective hospitals; thus, in one-third of the cases of outbreaks such breaches were observed in maternity clinics with insufficient material and technical equipment. The prevention of these breaches is considered to be the main road to the solution of the whole problem of the prevention of epidemic outbreaks in hospitals.