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R Pakula

Publications and source records attributed to R Pakula.

27 records · Page 2Linked to original sources
PubMed1967

Cellular sites for the competence-provoking factor of streptococci.

Immune globulins against competent cells of group H streptococci, strains Challis and Wicky, inhibited genetic transformation to streptomycin resistance when added to competent cultures. Antibodies against noncompetent cells did not inhibit transformation of competent cells. Strain Challis is spontaneously highly transformable. Strain Wicky is very poorly transformable but can be converted to high transformability with the exocellular competence-provoking factor (CPF) produced by strain Challis. Globulins against noncompetent cells of strain Challis and Wicky also inhibited transformation when added to noncompetent cultures prior to conversion to competence. Antibodies against cells of the related strain Blackburn, however, did not inhibit transformation under any circumstances. It is concluded that, although globulins prepared against competent cells block the deoxyribonucleic acid receptor sites present in these cells, the globulins prepared against noncompetent cells prevent conversion to competence by blocking the access of CPF to specific cellular sites for this factor. Strain Blackburn seems not to contain CPF-receptive sites and is, therefore, nontransformable.

Antigen-Antibody Reactions↗
PubMed1965

Factors regulating competence in transformation of streptococci.

Pakula, Roman (University of Toronto, Toronto, Ontario, Canada). Factors regulating competence in transformation of streptococci. J. Bacteriol. 90:1320-1324. 1965.-The highly transformable group H Streptococcus strain Challis produced an exocellular competence-provoking enzyme capable of converting to the state of competency incompetent cells of the homologous strain, and of the very poorly transformable strain Wicky. The competence-provoking activities of culture filtrates of strain Challis prepared at various periods of growth were tested on cells of strain Wicky. In the first 3 hr of growth, a strict correlation was found between the degree of competence and the competence-provoking activity. The period of maximal competency was followed by a rapid decline, although the competence-provoking activity of the filtrates remained at a maximum. The decay of competence was caused by a change in the structure of the cells which rendered them nonreceptive to the action of the competence-provoking enzyme.

DNA, Bacterial↗
PubMedDate not supplied

Polymorphism of indomethacin. Part II. Identification and rapid determination of polymorphic forms of indomethacin by IR spectrometry.

A procedure is described, which make it possible to determine the content of individual polymorphic forms of indomethacin in their mixture by IR spectrometry. IR spectra recorded in the range of 1600--1800 cm-1 have been used in the determinations. The method is especially useful for analytical control of the technological process of preparing the most pharmacologically active-gemma-form of indomethacin.

Indomethacin↗