A determinant encoding resistance against potassium tellurite (Te(r)) was discovered in a clinical isolate of Escherichia coli strain KL53. The strain formed typical black colonies on solid LB medium with tellurite. The determinant was located on a large conjugative plasmid designated pTE53. Electron-dense particles were observed in cells harboring pTE53 by electron microscopy. X-Ray identification analysis identified these deposits as elemental tellurium and X-ray diffraction analysis showed patterns typical of crystalline structures. Comparison with JCPDS 4-0554 (Joint Committee on Powder Diffraction Standards) reference data confirmed that these crystals were pure tellurium crystals. In common with other characterized Te(r) determinants, accumulation studies with radioactively labeled tellurite showed that reduced uptake of tellurite did not contribute to the resistance mechanism. Tellurite accumulation rates for E. coli strain AB1157 harboring pTE53 were twice higher than for the plasmid-free host strain. In addition, no efflux mechanism was detected. The potassium tellurite resistance determinant of plasmid pTE53 was cloned using both in vitro and in vivo techniques in low-copy-number vectors pACYC184 and mini-Mu derivative pPR46. Cloning of the functional Te(r) determinant into high-copy cloning vectors pTZ19R and mini-Mu derivatives pBEf and pJT2 was not successful. During in vivo cloning experiments, clones with unusual "white colony" phenotypes were found on solid LB with tellurite. All these clones were Mucts62 lysogens. Their tellurite resistance levels were in the same order as the wild type strains. Clones with the "white" phenotype had a 3.6 times lower content of tellurium than the tellurite-reducing strain. Transformation of a "white" mutant with a recombinant pACYC184 based Te(r) plasmid did not change the phenotype. However, when one clone was cured from Mucts62 the "white" phenotype reverted to the wild-type "black" phenotype. It was suggested that the "white" phenotype was the result of an insertional inactivation of an unknown chromosomal gene by Mucts62, which reduced the tellurite uptake.

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Aims:To determine whether simple linear measurements can be used as an accurate and reproducible replacement of the volumetric ones.Methods: We measured the cella media distance (CM1) and the distance between the right and left human brain surfaces (CM2) -measured along the CM1 line -in the groups of women (F) and men (M) who were divided according to diagnoses into three subgroups (F1-3 and M1-3). Examinations were carried out under standardized conditions: axial serial CT (Computed Tomography) images, in 4 mm layers (333 patients). Measured values were detected by Osiris Software. Recorded values were statistically analysed.Results: We found very highly significant (subgroups M1, M3), and significant (subgroups F1, F2, F3, M2) associations between the cella media distance and the decade of age. There were only non-significant differences in CM1 distances between men and women and between the diagnoses groups as well. Correlation between cella media distance and volume of lateral ventricles was greater in men in both, subgroup M1 (r = 0.659, P < 0.0001) and in a mixed group where all the three male subgroups M1-3 were combined into one group (r = 0.675, P < 0.0001). Among women the correlation was lower, however still significant (r = 0.357, P < 0.0001 for F1 and r = 0.465, P < 0.0001 for F1-3).Conclusions: The cella media distance is much better predictor of brain lateral ventricular volume in men than in women.