Cytochrome c peroxidase compound I: formation of covalent protein crosslinks during the endogenous reduction of the active site

Cytochrome c peroxidase (ferrocytochrome-c:hydrogen-peroxide oxidoreductase, EC 1.11.1.5) was oxidized by hydrogen peroxide in the absence of exogenous electron donor. Higher molecular weight species were observed in the decay products at pH 4.5. Monomer and dimer were separated by gel filtration and purified by anion-exchange chromatography. Peptide mapping of tryptic digests of the dimer indicated a tyrosine crosslink localized between residues 32 and 48 of the native enzyme.     

Differential induction of activation markers in macrophage cell lines by interferon-gamma

Macrophage cell lines were used in these studies as a model system to dissect the biochemical and functional mosaic of the macrophage activation process. In particular, the requirements for the induction of tumoricidal and bactericidal activity in the RAW 264.7 and WEHI-3 cell lines by interferon-gamma (IFN-gamma) and bacterial lipopolysaccharide (LPS) were determined. Changes in expression of a series of macrophage markers traditionally associated with macrophage activation were monitored during stimulation of the cells in order to determine whether a detectable pattern of activation-associated changes is associated with the development of a particular functional activity. These markers included changes in the cell surface expression of major histocompatibility complex-encoded Class I and Class II antigens and antigens in the Mac-1/LFA-1 family, alterations in the levels of membrane enzymes (5' nucleotidase and alkaline phosphodiesterase), and production of secretory products including hydrogen peroxide and the monokines interleukin-1, interferons-alpha/beta, and tumor necrosis factor-alpha. Our results demonstrate that a given homogeneous macrophage population expresses a distinct subset of functional activities in response to single, defined activating signals such as IFN-gamma and LPS. The display of a variety of macrophage surface antigens, enzymes, and secreted products is activated simultaneously by such treatment; however, the particular pattern of such activation-associated markers cannot reproducibly be used to predict the ability of an activated cell to perform a particular function. The results also suggest that macrophage cell lines expressing differential response patterns following IFN-gamma stimulation provide a valuable system for dissection of the molecular and cell biology of macrophage activation.     

C-src locus determines increased rate of Na+,K+-cotransport and increased calcium content in erythrocytes of (SHR x WKY) F2 hybrids

26 male F2 hybrids between spontaneously hypertensive (SHR) and normotensive control (WKY) rats (SHRxWKY)F2 were segregated according to their c-src genotype into SS and WW homozygous groups, corresponding to SHR or WKY and WS heterozygous group. Na, K cotransport in erythrocytes in the WW group was equal to that of WKY and differs significantly from that of WS and SS groups (the rate of Na, K cotransport in latter groups was close to that of SHR). Ca content of RBC in WW group was equal to that of WKY, lower than that of WS and SS groups which in turn was significantly lower than in SHR, indicating polygenic control of the trait. Authors conclude that the c-src locus itself or some other loci inherited in conjunction with c-src determines both the increase of Na, K cotransport and calcium content in erythrocytes of SHR.     

Phase changes in the population of group A streptococci and their influence on the course of the epidemic process of tonsillitis

This work presents the data on the complex evaluation of the population of group A streptococci, studied at each of four phases (reservation, epidemic transformation, epidemic spread, reservational transformation) of the course of the epidemic process of streptococcal infection of the respiratory tracts (tonsillitis) in an organized group of adults. The characterization of the phases of the infective agent in accordance with the level of the carrier state, the size of streptococcal foci and the virulence of streptococci is given. Thus, the study shows that the heterogeneity of group A streptococci with respect to their virulence reaches its maximum level at the phases of reservation and epidemic spread and its minimum level at the phases of epidemic and reservational transformation. The size of streptococcal foci in carriers and the virulence of streptococci isolated from them are the inter-related unidirectional signs of the population of the infective agent and, at the same time, the main factors responsible for the phase character of the epidemic process and the morbidity level in tonsillitis.     

The use of a mixture model in the analysis of count data

A mixture model is presented for the analysis of data on premature ventricular contractions. The analysis is shown to be straightforward and the conclusions relatively simple.