We present conclusive evidence for the chromosomal location of the lac gene in a lactose-fermenting Salmonella litchfield strain (AO Lac⁺). Two Hfr strains constructed from AO Lac⁺ had abilities to transfer the lac gene to S. typhimurium LT2 at relatively high frequencies. Detailed characterization of the transconjugants suggested that the lac in AO Lac⁺ was located on the host chromosome between galE (18min) and trpB (34min). Transduction experiments using P22 phage showed that the lac was cotransduced with gal, but not with trpB. These results clearly indicate that the lac gene is located at a position near 18min of the linkage map of Salmonella.

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The present study was conducted to determine the possible role of intracellular Ca²⁺ in lipid peroxide formation in endotoxin-poisoned mice. Leakages of LDH isozyme and acid phosphatase in serum of mice fed a Ca²⁺-deficient diet were remarkably increased after administration of 200μg of endotoxin compared to that in endotoxin-nontreated Ca²⁺-deficient mice. Superoxide anion generation in liver of Ca²⁺-deficient mice and in mice fed a normal diet greatly increased after endotoxin administration. On the contrary, after endotoxin injection there was scarcely any difference in SOD activity of liver of Ca²⁺-deficient mice as compared to that in endotoxin-nontreated Ca²⁺-deficient mice. In spite of an increase of superoxide anion generation there was little or no effect of endotoxin administration on lipid peroxide formation in mice given a Ca²⁺-deficient diet. In the mice treated with a Ca²⁺-deficient diet, free radical scavenger levels (α-tocopherol and nonprotein sulfhydryl) in liver tissue after endotoxin injection were markedly decreased compared to those in Ca²⁺-deficient diet alone. Mice fed a normal diet exhibited a significant decrease of lipid peroxide level in liver by injection of endotoxin together with verapamil (10mg/kg, s.c.). When mice fed a normal diet were injected with endotoxin, the state 3 respiratory activity showed a 49% decrease, and respiratory control ratio (RCR) of endotoxemic mice liver mitochondria was 38% lower than normal liver mitochondria. No difference could be observed in levels of state 3 and RCR between the mice given verapamil plus endotoxin and the normal mice. These findings suggest the possibility that Ca²⁺ may participate in the free radical formation in the liver during endotoxemia and also that Ca²⁺ may play an important role in the damage of liver mitochondrial function in endotoxemic mice.

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Using mouse tracheal organ cultures, the pathogenic effect of Bordetella bronchiseptica to epithelial cells was studied by electron microscopy. The ultrastructure of epithelial cells in uninfected tracheal rings was preserved well for longer than 3 days. In mouse tracheal rings infected with graded doses (3×10⁵ to 10⁷ CFU/ml) of phase I B. bronchiseptica, the colonization in the interciliary spaces of ciliated epithelial cells was observed after a 20-hr infection period. The infected tracheal rings showed swelling of nonciliated cells as well as ciliated cells, rupture of cell membrane of cilia, swelling and disappearance of cilia, and atrophic cytomorphosis of epithelial cells. The severity of these changes occurred depending on the infection doses. These changes were essentially similar to those observed previously in the tracheal epithelia of the B. bronchiseptica-infected mice. The usefulness of this in vitro model was suggested for studying the pathogenesis of Bordetella infection.

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The release of IgG-binding proteins from the cell surface of streptococcal strains AR-1 and G148 with various proteolytic enzymes, acid, alkali or SDS was investigated. The IgG-binding proteins were purified by affinity chromatography using IgG-Sepharose Fast Flow. After SDS-polyacrylamide gel electrophoresis and immuno-electroblotting the major proteins identified varied in relative molecular mass from 15, 000 to 65, 000 depending on the solubilizing agent used. The results showed that solubilization with trypsin gave the highest yield of IgG-binding proteins, that strain G148 yielded about twice the amount of protein as strain AR-1, and that elastase released an IgG-binding protein of high relative molecular mass of 65, 000.

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A non-radioactive DNA probe for the detection of Mycoplasma pulmonis was developed by using photobiotin. The probe detected 0.3ng chromosomal DNA of M. pulmonis. No cross-hybridization was observed between the probe and the other murine mycoplasma species, M. arthritidis and M. neurolyticum.

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Thirteen strains of Sendai virus isolated from various sources in the 1950's and after 1976 were compared for their reactivities with monoclonal antibodies prepared against the prototype strain MN of Sendai virus. Results revealed that while the 5 strains isolated in the 1950's reacted with all the monoclonal antibodies as the prototype strain did, the 2 strains isolated in 1976 and 1978 did not react with an F-specific monoclonal antibody, and the other 6 strains isolated after 1978 lacked reactivity with an HN-specific monoclonal antibody.

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Single-serum diagnosis of recent rubella infection was attempted with the use of hemagglutination inhibition (HI) test and two commercially available enzyme-linked immunosorbent assays (ELISAs). The period during which IgM antibody was detectable by IgM capture ELISA was 4 to 30 days after the onset of rash. Rubella IgG ELISA values relative to HI titer were lower in the sera from the patients with recent infection than in the sera from the subjects with remote infection. IgM ELISA and the combined use of IgG ELISA and HI test are two useful methods of single-serum diagnosis of recent rubella infection.

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Human lymphocytes and MT4 cells infected with a virus isolated from a patient with exanthem subitum were examined by transmission and scanning electron microscopy. The most striking characteristic of the ultrastructure of this herpes-type virus was that nucleocapsids located outside the nucleus were each coated distinctly with a tegument of moderate electron density. Tubular structures formed due to some mistakes in the viral assembly were also detected in the nucleus. Morphological differentiation of this virus from the other human herpesviruses was discussed. From these observations it was concluded that this virus has the same ultrastructural characteristics as HBLV (HHV-6).

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