A clinical isolate of Escherichia coli from a patient in Japan, isolate KU6400, was found to produce a plasmid-encoded ␤-lactamase that conferred resistance to extended-spectrum cephalosporins and cephamycins. Resistance arising from production of a ␤-lactamase could be transferred by either conjugation or transformation with plasmid pKU601 into E. coli ML4947. The substrate and inhibition profiles of this enzyme resembled those of the AmpC ␤-lactamase. The resistance gene of pKU601, which was cloned and expressed in E. coli, proved to contain an open reading frame showing 99.8% DNA sequence identity with the ampC gene of Citrobacter freundii GC3. DNA sequence analysis also identified a gene upstream of ampC whose sequence was 99.0% identical to the ampR gene from C. freundii GC3. In addition, a fumarate operon (frdABCD) and an outer membrane lipoprotein (blc) surrounding the ampR-ampC genes in C. freundii were identified, and insertion sequence (IS26) elements were observed on both sides of the sequences identified (forming an IS26 composite transposon); these results confirm the evidence of the translocation of a ␤-lactamase-associated gene region from the chromosome to a plasmid. Finally, we describe a novel plasmid-encoded AmpC ␤-lactamase, CFE-1, with an ampR gene derived from C. freundii.

To analyze polarized light scattering patterns from gels, an approach is proposed to calculate the scattered intensity. In the proposed model system, difference between polar angles of the principal axes of the and elements, which were defined with respect to the axis along the distance between two elements, was given as a correlation of the distance between the two elements. Furthermore, the azimuthal angle, which makes a projection of the principal axis onto a plane perpendicular to the principal axis of the element, was also given as a correlation of the distance between the two elements. The theoretical calculation was carried out for the scattered intensity under Hv and Vv polarization conditions. The general equations proposed for Hv and Vv scattering were based on a statistical approach for polarized light scattering system. The calculated pattern under the Hv polarization condition showed an X-type pattern and was in good agreement with the pattern observed from polymer gels prepared by quenching their solutions to the desired temperatures.

The origins of the thermal and mechanical properties of chitosan and poly(vinyl alcohol) (PVA) with inter-and intra-hydrogen bonds were investigated systematically by using X-ray, DSC, positron annihilation and viscoelastic measurements. Based on their individual properties, the characteristics of the blend films were estimated in relation to their morphology and mechanical properties as a function of chitosan content. The characteristics of the blend films were also analyzed in terms of the deviation from a simple additive rule of chitosan and PVA content. These results suggested that the miscibility of chitosan and PVA could be ensured by entanglement of the amorphous chain segments of chitosan and PVA. Further detailed analysis revealed that the chitosan content on the film surface is higher than that of the admixture content of chitosan after elongation, although the chitosan and PVA chains were crystallized independently. The elongation could be achieved for the blend films whose PVA content was higher than 50% and the drawn blend films were transparent. Thus, it may be expected that sufficiently entangled meshes formed between chitosan and PVA amorphous chains within the film, the PVA content being higher than 50%, were maintained under the elongation process.

Orientation behavior of carbon fibers (CFs) in polymer solution/gel under magnetic field was estimated in terms of the orientation distribution function. The estimation was done by a series of spherical harmonics of the orientation distribution function of the reciprocal lattice vector of the (002) plane measured for the composite films. Despite a number of papers concerning the orientation of CFs and carbon nanotubes under magnetic field, all estimations have been done in terms of the second-order orientation factor of the (002) plane. The work described in this paper was first successful for the direct estimation of orientation of CF axes within the dried film in terms of orientation function by considering a random orientation of the CF axes around the magnetic field direction. In this experiment, poly(vinyl alcohol) (PVA) was adopted as the solution to disperse CFs and to prepare the composite films by evaporating solvent. The normalized function obtained experimentally was analyzed in comparison with the magnetic orientation of CFs in solution or gel at the equilibrium state calculated by the magnetic energy of CF. Furthermore, the orientation of the CFs up to the equilibrium state in the given systems was estimated as a function of time by a common diffusion equation. The calculated results indicated that the preferential orientation of CFs with respect to the magnetic field direction becomes promoted with elapsing time. This tendency became significant, when the contents of CFs and/or PVA were less than the critical concentration within the dispersion solution. The experimental and theoretical results, however, provided that the preferential orientation degree became lower drastically, when the PVA content and/or the CF content were beyond their critical concentration. This was due to a drastic decrease in viscosity of the dispersion solution before gelation/crystallization.

To investigate the emergence of rifampin resistance in Rhodococcus equi strains isolated from foals and their environment in Japan, we compared the in vitro antimicrobial susceptibilities to rifampin of 640 isolates from 64 infected foals and 98 soil isolates from their horse-breeding farms. As a control, 39 human isolates from patients with and without AIDS were also tested for susceptibility to rifampin. All of the isolates showed rifampin sensitivity, except isolates from one infected foal and two patients with AIDS that showed rifampin resistance. To investigate the emergence of rifampin-resistant R. equi in the infected foal, which had received rifampin monotherapy for a month before euthanasia, 99 isolates of R. equi from the lesions and 20 isolates from the intestinal contents of the one foal with rifampin-resistant organisms were analyzed for rifampin susceptibilities, pathogenicities, and ribotypes. Of the 99 isolates from the lesions, all of which were virulent R. equi strains containing a virulence plasmid with a size of 85 or 90 kb, 90 (91%) isolates were rifampin resistant (MIC, м12.5 g/ml). On the other hand, of the 20 isolates from the intestinal contents, 11 (55%) isolates showed rifampin resistance (MIC, м25 g/ml), and 5 of them were avirulent R. equi strains. Among these 101 rifampin-resistant R. equi isolates with and without virulence plasmids characterized by ribotyping, 58 were type I, 20 were type II, 11 were type III, and 12 were type IV. These results demonstrated that at least eight different rifampin-resistant R. equi strains emerged concurrently and respectively from the different lesions and intestinal contents of the infected foal.