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C Oka

Publications and source records attributed to C Oka.

30 records · Page 2Linked to original sources
PubMed1980

Spontaneous emergence of an Hfr strain with a cit plasmid from natural isolates of citrate-positive Escherichia coli bovine origin.

From citrate-utilizing (Cit+) Escherichia coli strain C53 of bovine origin, strains C53A and C53B were obtained. Upon mating with recA+ but not with recA mutant recipients of K-12, C53A produced chromosomal recombinants at quite high frequencies, leading to the following conclusions: (i) C53A is an Hfr strain; (ii) the site of integration of the Cit plasmid (IncH1) is between metA (89 min) and ara (1 min); (iii) the direction of chromosome transfer is clockwise; and (iv) the plasmid-associated determinants are transferred as the terminal markers. A transductant of a dnaA(Ts) strain, CRT46, which acquired Cit determinants from a recombinant, SG13, was also an Hfr strain similar to SG13, and thermoresistant due to suppressive integration. On the other hand, unstable C53B did not produce recombinants, but the frequency of RecA-independent transfer of the Cit plasmid was high, indicating that the Cit plasmid (IncH1) exists autonomously in C53B. Attempts to isolate an Hfr strain from C53B failed.

Animals↗
PubMed1979

Plasmids in Escherichia coli controlling citrate-utilizing ability.

The citrate-utilizing ability of 19 out of 22 citrate-positive Escherichia coli strains isolated from pig sewage was transferred via conjugation to E. coli K-12. The conjugal transfer of citrate-utilizing (Cit) abilities was thermosensitive and concurrent with transfer of drug resistance. Weakly citrate-positive colonies were readily obtained in conjugation experiments. Their Cit characters could be transmitted to the other E. coli strains at a similar frequency in the retransfer experiments, and the transconjugants obtained still showed same characteristic growth on Simmons citrate agar plates. The 19 thermosensitive plasmids conferring citrate utilization and drug resistance were Fi-, and 16 of these plasmids belonged to incompatibility group H1. However, occasionally two conjugative plasmids (pOH3122-1 and pOH3124-1) carrying only the citrate utilization were also obtained in the conjugation experiments, and they were Fi+ and compatible with 19 reference R plasmids. In the two citrate-positive E. coli strains, it was suggested that the conjugative Cit plasmid showing Fi+ character and the more thermosensitive H1 plasmid conferring both the Cit character and drug resistance coexisted in the strain. The characterization of citrate utilization plasmids derived from pig farm sewage is discussed.

Animals↗
PubMed1978

Isolation of citrate-positive variants of Escherichia coli from domestic pigeons, pigs, cattle, and horses.

Twenty-seven isolates of citrate-positive variants of Escherichia coli were obtained from domestic pigeons, pigs, cattle, and horses. With the exception of citrate utilization, all isolates closely resembled typical E. coli in their biochemical reactions. These isolates were multiply resistant to antibiotics in in vitro susceptibility tests. Transfer experiments of multiple-drug resistance to the E. coli K-12 strain showed that all citrate-positive isolates from domestic pigeons, pigs, and cattle, resistant to three or more drugs, carried R plasmids showing temperature-sensitive transfer.

Animals↗
PubMed1978

Detection of conjugative R plasmids conferring chloramphenicol resistance in Escherichia coli isolated from domestic and feral pigeons and crows.

A total of 87 domestic pigeons of 2 lots and 184 feral pigeons of 15 lots were examined from 1975 to 1977 for the presence of drug-resistant (especially chloramphenicol resistant) Escherichia coli. 20 (23.0%) of the domestic pigeons of the 2 lots, and 39 (21.2%) of the feral pigeons of 5 lots (33,3%) showed resistant E. coli. Usage of selective media containing chloramphenicol, streptomycin or tetracycline resulted in the increase in isolation frequency of resistant E. coli excepting one lot of domestic pigeons in which isolation of chloramphenicol resistant E. coli was very frequent without selection by the drug. Among a total of 106 resistant E. coli isolates from pigeons, 64 (60.4%) were multiply resistant and 58 of the 64 isolates were resistant to chloramphenicol. 58 (90.6%) of the multiply resistant E. coli carried conjugative R plasmids, including 13 thermosensitive R plasmids. 8 (19.0%) of 42 singly resistant E. coli isolates had conjugative R plasmids. 10 crows of 2 lots were examined similarly. Half of them had resistant E. coli. 15 (78.9%) of a total of 19 resistant E. coli isolates were multiply resistant. Of the 15 multiply resistant E. coli isolates, 5, from 2 Japanese jungle crows, were resistant to chloramphenicol. 11 (73.3%) of the 15 multiply resistant isolates carried conjugative R plasmids, including one thermosensitive R plasmid. Difference of drug resistance status between Salmonella and E. coli isolated from pigeons was discussed.

Animals↗
PubMedDate not supplied

Risk of retinal detachment in patients with lattice degeneration.

To determine the risk of retinal detachment in patients with lattice degeneration of the retina, we statistically analyzed the incidence of retinal detachment in these patients. The data of hospital patients with retinal detachment associated with lattice degeneration in Kumamoto Prefecture, Japan, in 1990 were collected. The prevalence of lattice degeneration in Kumamoto was reported to be 9.5% in 1980. Based on population data from the 1990 census, the cumulative incidence of retinal detachment associated with lattice degeneration was calculated in this study. Among 1,840,000 residents in Kumamoto, there were 110 patients with retinal detachment associated with lattice degeneration; 72 with detachment resulting from tractional tears (tears), and 38 with detachment from atrophic holes. The cumulative incidence of retinal detachment from atrophic holes was 1.5% at the age of 40 years; from tears it was 3.6% at the age of 80 years. The cumulative incidence of detachment from both atrophic holes and tears was 5.3% at the age of 80 years. The results of this study are useful for clarifying the natural course of lattice degeneration.

Adolescent↗