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Biomedical subjects

D M Yajko

Publications and source records attributed to D M Yajko.

45 records · Page 3Linked to original sources
PubMed1985

Incidence and characterization of beta-hemolytic Streptococcus milleri and differentiation from S. pyogenes (group A), S. equisimilis (group C), and large-colony group G streptococci.

The biochemical characteristics of 172 clinical isolates of group A, C, F, or G or "nongroupable" beta-hemolytic streptococci were examined. Among these isolates, 91 were identified as beta-hemolytic strains of Streptococcus milleri. The remaining isolates included 20 Streptococcus pyogenes, 21 Streptococcus equisimilis, 37 large-colony group G streptococci, and 3 unidentified nongroupable isolates. A majority (84%) of the S. milleri strains possessed Lancefield group antigen (3 A, 27 C, 41 F, and 5 G), whereas 15 S. milleri strains (16%) were nongroupable. Serological tests did not differentiate S. milleri isolates with group A, C, or G antigen from S. pyogenes (group A), S. equisimilis (group C), or large-colony group G streptococci. Biochemical tests which were found useful for differentiation included the Voges-Proskauer test, hydrolysis of pyroglutamic acid and beta-D-glucuronide, bacitracin susceptibility, and acid production from ribose. S. milleri represented 56% of the group C, 100% of the group F, and 83% of the nongroupable beta-hemolytic streptococci isolated in our clinical laboratory, whereas the incidence of S. milleri among group A and group G streptococci was estimated to be low. The role of beta-hemolytic S. milleri as a cause of human infection remains obscured by the failure to routinely differentiate S. milleri from other beta-hemolytic streptococci.

Hemolysis↗
PubMed1984

Evaluation of PPLO, A7B, E, and NYC agar media for the isolation of Ureaplasma urealyticum and Mycoplasma species from the genital tract.

Four agar media (PPLO, NYC, A7B, and E) which are commonly used for the isolation of urogenital tract Mycoplasma species and Ureaplasma urealyticum were compared by culturing swabs of the endocervix of 334 pregnant women on all four media. To permit growth of both Mycoplasma and U. urealyticum, selective ingredients were omitted from the media tested. A7B and E agar were both satisfactory for the isolation of Mycoplasma species, recovering 92 and 82%, respectively, of all Mycoplasma species isolated. Only A7B agar was satisfactory for U. urealyticum isolation, recovering 96% of all isolates. Several modifications of PPLO, NYC, and E agar failed to significantly improve recovery of U. urealyticum on these media. A7B agar was clearly superior to all other media tested in terms of recovery rate, typical appearance of colonies, and ease of reading. A7B can be used for the isolation of both U. urealyticum and Mycoplasma species from urogenital sites.

Agar↗
PubMed1984

Rapid confirmatory identification of Neisseria gonorrhoeae with lectins and chromogenic substrates.

A group of five tests utilizing wheat germ and soybean lectins and chromogenic substrates (orthonitrophenyl-beta-D-galactopyranoside, gamma-glutamyl-beta-naphthylamide, and prolyl-beta-naphthylamide derivatives) was used as a rapid (30-min) method for the identification of Neisseria gonorrhoeae. The rapid method agreed with Minitek test results for all 126 N. gonorrhoeae isolates and all 39 nongonococcal isolates tested. Soybean lectin was useful for the identification of rare strains (4 of 126) of N. gonorrhoeae which are not agglutinated by wheat germ lectin. The chromogenic substrates differentiate N. gonorrhoeae from Neisseria meningitidis, Neisseria lactamica, and other Neisseria species which may grow on Thayer-Martin or other selective media.

Agglutination Tests↗
PubMed1978

Changes in cyclic AMP levels during development in Myxococcus xanthus.

Cyclic AMP levels doubled in Myxococcus xanthus under conditions in which cells aggregate and form fruiting bodies. In liquid medium, glycerol- or dimethyl sulfoxide-induced sporulating cultures exhibited a sharp but transient rise in cyclic AMP concentration after 45 min.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1975

Mutations simultaneously affecting endonuclease II and exonuclease III in Escherichia coli.

We studied mutants of E. coli originally identified as being deficient in either endonuclease II (deoxyribonucleate oligonucleotidohydrolase, EC 3.1.4.30) or exonuclease III [deoxyribonucleate (double-stranded) 5'-nucleotidohydrolase, EC 3.1.4.27] activity. Twelve independently derived mutants were tested, including three new endonuclease II mutants. Deficiency of one enzyme was always accompanied by deficiency of the other. Furthermore, temperature-sensitivity of one activity was always accompanied by temperature-sensitivity of the other, and the enzymes were co-purified. The results suggested a physical association between exonuclease III and endonuclease II, which may be of advantage in the excision-repair of DNA. A thermolabile endonuclease II was purified from one of the new mutants, indicating that it had an altered structural gene. This mutation, and all similar ones mapped by genetic transduction, was located between the pncA and aroD genes on the E. coli chromosome. One mutant had a prolonged generation time, an increased sensitivity to the alkylating agents methyl-methanesulfonate and mitomycin C, and a decreased plating efficiency for bacteriophage lambda, but no marked sensitivity to ultraviolet or gamma-irradiation. Its enzymatic and biological abnormalities were simultaneously revertible, suggesting they were caused by a single mutation. These results suggested a role for these enzymes in normal cell growth processes and in the repair of alkylation damage.

Chromosome Mapping↗
PubMed1971

Tumor induction by Agrobacterium tumefaciens: specific transfer of bacterial deoxyribonucleic acid to plant tissue.

When Agrobacterium tumefaciens cells grown in the presence of tritiated thymidine to label specifically the bacterial deoxyribonucleic acid (DNA) are incubated with carrot root tissue for short periods of time, an appreciable fraction of the label becomes firmly associated with the root tissue. Such association is not observed in identical experiments when A. tumefaciens cell ribonucleic acid or protein are labeled. The extent of the retention of thymidine-derived label from bacterial cells by the root tissue in experiments with A. radiobacter and poorly tumorigenic strains of A. tumefaciens is significantly less than that afforded by tumorigenic strains of A. tumefaciens but greater than the level afforded by Escherichia coli. Transfer of DNA-specific label from A. tumefaciens to carrot root discs is not enhanced by treatments designed to provoke lysis of the bacterial cells, nor is it decreased by addition of deoxyribonuclease or excess unlabeled thymidine to the incubation medium. Bacterial cell-to-plant cell contact is necessary for transfer. Unlabeled A. radiobacter cells decrease in a competitive manner transfer of label when mixed with labeled A. tumefaciens cells. These findings suggest that transfer of DNA from A. tumefaciens to plant tissue after binding of the bacterial cells to specific plant tissue site(s) is a necessary feature of the mechanism by which A. tumefaciens provokes tumors in plants and provides an experimental technique of potentially great value in study of the early steps in the process of tumor induction by A. tumefaciens.

Animals↗