Substructure of the Cytoplasmic Membrane of Bacillus megaterium

The components of fractions obtained by dialyzing and differential centrifuging the “Ghost” of Bacillus megaterium were analyzed in detail. The compositions of amino acids in the main fractions (Fraction 2 and 3) of the “Ghosts”, were estimated. Fraction 2 was rich in non-polar amino acids, while Fraction 3 was scanty of them. Most of the fatty acids in Fraction 2 were 12-methyl tetradecanoic acid, while in Fraction 3 many kinds of fatty acid were detected.

As for the localization of enzymes, the three enzymes, glucose oxidase, succinic dehydrogenase and reduced nicotinamide-adenine dinucleotide oxidase, which were present in the original “Ghosts”, were mostly observed in Fraction 2, and a very little amount of them was found in the other fractions. Further, Fraction 2 could be dissolved in formic acid and dialysis of the solution brought about reaggregation to form membrane-like structure in the presence of Ca or Mg ion.     

Proton magnetic resonance spectra of tetracyclic triterpene alcohols under the influence of a lanthanide shift reagent.

The proton magnetic resonance spectra were measured for four series of tetracyclic triterpen-3beta-ols, i.e. 5alpha-lanostane, 5alpha-euphane, 5alpha-tirucallane, and 5alpha-dammarane series, in the presence of a molar equivalent of tris (dipivalomethanato) europium, a lanthanide shift reagent. The spectral pattern measured in the presence of the shift reagent was found useful for distinguishing each series and also for characterizing each skeletal isomer of tetracyclic triterpene alcohols.     

Analysis of the mode of antigen presentation required for triggering of T cell proliferation by using various azobenzenearsonate-tyrosine derivatives

Various azobenzenearsonate-tyrosine (ABA-Tyr) derivatives were synthesized by modifying amino and carboxyl groups at the alpha-carbon of tyrosine, with preservation of most of the ABA-Tyr moiety (ABA plus hydroxyphenyl portion of tyrosine). These derivatives were tested for the ability to stimulate ABA-L-Tyr specific T cell lines derived from B10.BR and B10.S mice. ABA-acetyltyramine, ABA-hydroxyphenylpropionic acid (ABA-PPr), and ABA-propylphenol, which lack either the carboxyl or amino group or both, could not induce T cell proliferation. The lack of stimulation by these derivatives was not due to their cytotoxic effects. A similar pattern of proliferation was obtained on stimulating lymph node T cells from B10.BR and B10.S mice primed with ABA-L-Tyr. Some differences were observed, however, between B10.BR and B10.S mice. ABA-L-Tyr-specific T cells from B10.BR mice could not respond well to ABA-D-Tyr in contrast to B10.S T cells. Furthermore, B10.BR mice primed with ABA-acetyltyramine or ABA-PPr in complete Freund's adjuvant could not induce ABA-L-Tyr-reactive T cells, whereas T cells from B10.S mice primed with these derivatives could proliferate in the presence of ABA-L-Tyr. The differences between B10.BR and B10.S mice were further investigated by using (B10.S X B10.BR)F1 mice. T cells from ABA-L-Tyr-immunized F1 mice responded poorly to ABA-D-Tyr when presented with B10.BR antigen-presenting cells (APC), but responded well when presented with B10.S APC. Similarly, T cells from ABA-PPr-primed F1 mice did not proliferate to ABA-L-Tyr in the presence of B10.BR APC, but could proliferate in the presence of B10.S APC. Our results clearly indicate that the presence of charged groups at the alpha-carbon of tyrosine plays a critical role in the triggering of ABA-L-Tyr-specific T cell proliferation. The significance of these results is discussed.     

Aggregatibacter actinomycetemcomitans induces detachment and death of human gingival epithelial cells and fibroblasts via elastase release following leukotoxin‐dependent neutrophil lysis

Aggregatibacter actinomycetemcomitans is considered to be associated with periodontitis. Leukotoxin (LtxA), which destroys leukocytes in humans, is one of this bacterium's major virulence factors. Amounts of neutrophil elastase (NE), which is normally localized in the cytoplasm of neutrophils, are reportedly increased in the saliva of patients with periodontitis. However, the mechanism by which NE is released from human neutrophils and the role of NE in periodontitis is unclear. In the present study, it was hypothesized that LtxA induces NE release from human neutrophils, which subsequently causes the breakdown of periodontal tissues. LtxA‐treatment did not induce significant cytotoxicity against human gingival epithelial cells (HGECs) or human gingival fibroblasts (HGFs). However, it did induce significant cytotoxicity against human neutrophils, leading to NE release. Furthermore, NE and the supernatant from LtxA‐treated human neutrophils induced detachment and death of HGECs and HGFs, these effects being inhibited by administration of an NE inhibitor, sivelestat. The present results suggest that LtxA mediates human neutrophil lysis and induces the subsequent release of NE, which eventually results in detachment and death of HGECs and HGFs. Thus, LtxA‐induced release of NE could cause breakdown of periodontal tissue and thereby exacerbate periodontitis.     

Phylogenetic position of Rickettsia tsutsugamushi and the relationship among its antigenic variants by analyses of 16S rRNA gene sequences

Abstract The 16S rRNA gene sequences of Rickettsia tsutsugamushi and Rickettsia sibirica were determined by PCR and DNA sequencing. Phylogenetic analysis revealed that R. sibirica is positioned in a cluster of the genus Rickettsia with a similarity value of 98.1–99.6%, whereas R. tsutsugamushi is located apart from the cluster with a similarity value of 90.2–90.6%. This evidence suggests that R. tsutsugamushi should be excluded taxonomically from the genus Rickettsia . The phylogenetic classification of six antigenic variants in R. tsutsugamushi moderately reflected their antigenic relationship known in closely and distantly related strains.     

Bioisostere of valtrate,anti-HIV principle by inhibition for nuclear export of Rev

Rational design by the MO calculation disclosed 5,6-dihydrovaltrate (2) as the bioisostere of valtrate (1), the Rev-export inhibitor with anti-HIV activity. The synthesis of 2 was accomplished by ingenious use of asymmetric Diels–Alder reaction and stereoselective epoxidation associated with the adjacent hydroxyl group. Because of similar biological potency to 1, the analog 2 should be recognized as a promising scaffold for new anti-HIV agents with an unprecedented mechanism of action, inhibition for nuclear export of Rev protein, in the conventional remedy.