The prevalence of Shiga toxin-producing Escherichia coli (STEC) in Japan was examined by using stool samples from 87 calves, 88 heifers, and 183 cows on 78 farms. As determined by screening with stx-PCR, the prevalence was 46% in calves, 66% in heifers, and 69% in cows; as determined by nested stx-PCR, the prevalence was 100% in all animal groups. Of the 962 isolates picked by colony stx hybridization, 92 isolates from 54 farms were characterized to determine their O serogroups, virulence factor genes, and antimicrobial resistance. Of these 92 isolates, 74 (80%) could be classified into O serogroups; 50% of these 74 isolates belonged to O serogroups O8, O26, O84, O113, and O116 and 1 isolate belonged to O serogroup O157. Locus of enterocyte effacement genes were detected in 24% of the isolates, and enterohemorrhagic E. coli (EHEC) hlyA genes were detected in 72% of the isolates. Neither the bundle-forming pilus gene nor the enteropathogenic E. coli adherence factor plasmid was found. STEC strains with characteristics typical of isolates from human EHEC infections, which were regarded as potential EHEC strains, were present on 11.5% of the farms.

Nineteen, 7- to 13-week-old pigs were inoculated intranasally with different strains of Haemophilus parasuis (serovar 1, 4 and 5), and the pathological lesions induced by each strain were compared. Eleven of thirteen pigs inoculated with either strain Nagasaki (serovar 5) or No. 4 (serovar 1) died between days 1 to 6 after inoculation, and had septicemic lesions, meningitis, or polyserositis. One of six pigs inoculated with strain SW124 (serovar 4) died with polyserositis, another one recovered after illness, and the remaining four pigs remained in good health. Five of the septicemic pigs had thrombi at many organs. Endotoxin was detected in the plasma of 10 pigs in the acute stage of infection. Using the immunoperoxidase technique, H. parasuis antigen was detected in lesions of infected pigs. In the serosal lesions the bacterial antigen was found mainly in the cytoplasm of infiltrating neutrophils and macrophages and appeared as degenerated bacteria and/or lytic bacterial material in dilated phagosomes. Many of the bacteria in the blood vessels of pigs with septicemic lesions were also degenerated. Although H. parasuis was reisolated from nasal secretions of infected pigs, the bacterial antigen could not be detected in the nasal cavities of these pigs. No lesions were observed in the parenchyma of the lung. However, H. parasuis antigen was detected in the tonsil of infected pigs.

New fluorescent reagents, 2,2‘-[oxybis(3-oxapentamethyleneoxy)]-bis[N-(1-pyrenylmethyl)benzamide)] (4) and its analogues (2, 3, and 5) which have two pyrenes at the both terminals of polyoxyethylene compounds, were synthesized, and their complexation behavior with alkaline earth cations was investigated by fluorescence spectrometry, fluorescence lifetimes, and 1H NMR spectrometry. These reagents (3−5) showed strong intramolecular excimer emissions around at 480 nm in the fluorescence spectra. On the complexation with alkaline earth metal cations, the increase of monomer emission around at 400 nm accompanied by the disappearance of intramolecular excimer emission of free reagents was observed. These reagents formed a 1:1 complex, and the order of complex formation constants was Ca2+ ≅ Sr2+ > Ba2+ > Mg2+ > Li+ for all reagents. 1H NMR spectra of these complexes with alkaline earth cations suggested the helical structures of the complexes. Fluorescence spectral changes at the formation of complexes depended on the chain length of the oxyethylene moiety and metal cations. In all cases, the formation of helical structures at the complexation was supported by the 1H NMR spectra.

New fluorophores based on linear polyether N,N′-[oxybis(3-oxapentamethylenoxy)-2-phenyl]bis(9-anthracenecarbonamide) (3) and its analogues (2 and 4) have been synthesized, and their complexation properties with various alkali-metal and alkaline-earth-metal ions were investigated by fluorescence, UV, and 1 H NMR spectroscopies. In the absence of metal ion, 2-4 showed almost no fluorescence emission (fluorescence quantum yield Φ ) 0.0003, fluorescence "off" state) since twisted intramolecular charge transfer (TICT) occurred through the amide bond. However, 2-4 demonstrated a significant increase in fluorescence intensity around 430 nm upon complexation with alkaline-earth-metal ions. In the case of 4‚Ca 2+ , a large enhancement effect on the fluorescence quantum yield (Φ ) 0.014, [Ca 2+ ]/[4] ) 5, Φ 4‚Ca 2+ /Φ free 4 ) 42, fluorescence "on" state) was observed. This "off-on" fluorescence characteristic was originated from the cooperative strong binding mode between the carbonyl group and the ethylenoxy moiety for alkaline-earth-metal ions, resulting in effective inhibition of photoinduced TICT relaxation. Fluorophores 2-4 formed a 1:1 complex (the order of the complex formation constants was Ca 2+ > Sr 2+ ≈ Ba 2+ ) and showed no considerable spectral changes upon complexation with alkali-metal ions and Mg 2+ . The 1 H NMR study on 2-4 and their complexes indicated that free 2-4 formed a helical structure. After complexation, the conformational change of 2 from a helical structure to a semicircular structure was observed. The pseudocyclic form was supported as the complex structure of 3, whereas the large conformational change of 4 was not observed after the addition of metal ions.

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