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Biomedical subjects

M Rýc

Publications and source records attributed to M Rýc.

10 recordsLinked to original sources
PubMed1979

Biological activity of synthetic subunits of streptococcus peptidoglycan. I. Pyrogenic and thrombocytolytic activity.

The ability of some synthetically prepared analogues of Streptococcus peptidoglycan subunits (dipeptide, tetrapeptide, glycodipeptide and glycotetrapeptide) to cause fever in rabbits and lysis of rabbit blood platelets was studied. While di- and tetrapeptides did not exhibit these activities, glycodipeptides and glycotetrapeptides displayed pyrogenic and thrombocytolytic activities comparable with those of natural peptidoglycans.

Blood Platelets↗
PubMed1979

Infantile gastroenteritis virus.

The authors demonstrated presence of virus particles of 55--75 nm manifesting morphological properties of the virus of infantile gastroenteritis (rotavirus, orbivirus, reo-like virus) by means of the electron microscopy, when investigating samples of stools of children sufferring from non-bacterial diarrheal diseases. Stool extracts were incubated with commercial gamma globulins or with convalescent sera provoking formation of extensive immunocomplexes. The complexes do not form when stool extracts are incubated with sera obtained from initial stages of the disease. This finding is an evidence of the presence of the virus in question among our population.

Age Factors↗
PubMed1978

Biological characteristics of peptidoglycans of group A streptococcus and some other bacterial species. II. Immunological mechanisms involved in thrombocytolysis.

Immunological mechanisms are involved in the thrombocytolytic activity of peptidoglycan of Group A streptococcus, Streptococcus pneumoniae and Staphylococcus aureus. Inactivation of particular components of complement (heating of blood serum to 56 degrees C,incubation with zymosan or NH4OH) inhibited the thrombocytolytic activity of group A streptococcus peptidoglycan. So did preincubation of Group A streptococcus peptidoglycan with homologous antipeptidoglycan antibody. On the other hand, antibody to Group A streptococcus peptidoglycan did not inhibit the thrombocytolytic effect of Streptococcus pneumoniae or Staphylococcus aureus peptidoglycan. Human platelets are resistant to peptidoglycans. They remain resistant in the presence of rabbit serum although rabbit platelets are highly sensitive to peptidoglycans. This suggests that, for the expression of the thrombocytolytic activity of bacterial peptidoglycan, specific receptors on the surface of platelets must be present in addition to serum factors.

Animals↗
PubMed1977

Biological characteristics of peptidoglycans of group A streptococcus and some other bacterial species. I. Tolerance and effect of antibody in fever response, and heart damaging effect in rabbits.

Induced tolerance to the pyrogenic action of group A streptococcus peptidoglycan decreased after one week and was no longer detectable after the second week. However, one or two further doses of peptidoglycan rapidly restored the tolerance. The passive transfer of plasma from rabbits tolerant to streptococcus peptidoglycan to nontolerant animals failed to transfer tolerance. Antiserum to streptococcus peptidoglycan neutralized the pyrogenic effect of not only streptococcus but also staphylococcus and pneumococcus peptidoglycan; it did not influence the febrile response to endotoxin. Histopathologic changes in the rabbit heart produced by the intravenous injection of staphylococcus or pneumococcus peptidoglycans were similar and were characterized by various stages of degeneration and necrosis. The changes were less pronounced than after streptococcus peptidoglycan. Antiserum to streptococcus peptidoglycan had modest or no counteracting effect on the development of heart alterations after staphylococcus or pneumococcus peptidoglycan.

Animals↗
PubMed1975

The thrombocytolytic activity of bacterial peptidoglycans.

The peptidoglycan of group A Streptococcus prepared by hot formamide or TCA extraction has an expressive ability to lyse rabbit blood platelets in vitro. Initial changes in the ultrastructure of platelets can be observed after 10 minutes incubation of rabbit platelets with 0.1 mug of Streptococcus peptidoglycan per ml. The submicroscopic alterations are characterized by changes of the shape and damage of the limiting membrane of the platelets. Larger amounts of peptidoglycan (10 mug/ml and more) cause total destruction of platelets; only remainders of the limiting membrane and free granulomers can be seen. Peptidoglycans of Streptococcus pneumoniae and Staphylococcus aureus exhibit a comparable effect on rabbit platelets. There are substantial differences in the sensitivity of blood platelets of different animal species to the streptococcal peptidoglycan. Rat platelets exhibit a similar thrombocytolytic effect after the Streptococcus peptidoglycan treatment as rabbit ones; however, the development of comparable changes in their submicroscopic structure needs a dose of peptidoglycan 10(2)-10(3) times higher. Platelets of guinea-pig, dog, cat, calf and human appear to be quite resistant under analogous conditions to as such a high dose of Streptococcus peptidoglycan as 500 mug/ml.

Animals↗
PubMed1975

Biophysical properties of coronavirus strain OC 43.

Coronavirus OC 43 from suckling mouse brains was subjected to sucrose density gradient centrifugation. Maxima of complement fixing (CF) activities occurred in the ribosomal (density 1.14) and mitochondrial (density 1.19) fraction which contained incomplete, damaged virus particles. The haemagglutinating (HA) activity was associated with the microsomal soluble protein fraction displayed no antigenic activity. The isolated purified virus proved to be very unstable.

Animals↗