Antiviral activity of acidic polysaccharides from Coccomyxa gloeobotrydiformi, a green alga, against an in vitro human influenza A virus infection.

The extracts prepared from green algae are reported to possess a variety of biological activities including antioxidant, antitumor and antiviral activities. The acidic polysaccharide fraction from a green alga Coccomyxa gloeobotrydiformi (CmAPS) was isolated and the antiviral action on an in vitro infection of influenza A virus was examined. CmAPS inhibited the growth and yield of all influenza A virus strains tested, such as A/H1N1, A/H2N2, A/H3N2 and A/H1N1 pandemic strains. The 50% inhibitory concentration of CmAPS on the infection of human influenza A virus strains ranged from 26 to 70 µg/mL and the antiviral activity of CmAPS against influenza A/USSR90/77 (H1N1) was the strongest. The antiviral activity of CmAPS was not due to the cytotoxicity against host cells. The antiviral activity of CmAPS required its presence in the inoculation of virus onto MDCK cells. Pretreatment and post-treatment with CmAPS was ineffective for the antiviral activity. CmAPS inhibited influenza A virus-induced erythrocyte hemagglutination and hemolysis. Taken together, CmAPS was suggested to exhibit the anti-influenza virus activity through preventing the interaction of virus and host cells. The detailed antiviral activity of CmAPS is discussed.

Evaluation of bactericidal effects of low-temperature nitrogen gas plasma towards application to short-time sterilization.

To develop a novel low-temperature plasma sterilizer using pure N(2) gas as a plasma source, we evaluated bactericidal ability of a prototype apparatus provided by NGK Insulators. After determination of the sterilizing conditions without the cold spots, the D value of the BI of Geobacillus stearothermophilus endospores on the filter paper was determined as 1.9 min. However, the inactivation efficiency of BI carrying the same endospores on SUS varied to some extent, suggesting that the bactericidal effect might vary by materials of sterilized instruments. Staphylococcus aureus and Escherichia coli were also exposed to the N(2) gas plasma and confirmed to be inactivated within 30 min. Through the evaluation of bactericidal efficiency in a sterilization bag, we concluded that the UV photons in the plasma and the high-voltage pulse to generate the gas plasma were not concerned with the bactericidal effect of the N(2) gas plasma. Bactericidal effect might be exhibited by activated nitrogen atoms or molecular radicals.

Comparison of the protein composition of breast milk and the nutrient intake between Thai and Japanese mothers.

This study compared the protein composition of breast milk and the nutrient intake between Thai and Japanese lactating mothers. The breast milk was collected from 15 Thai and 14 Japanese mothers at the fifth day post-partum. Twenty-four-hour dietary records were performed from the second-to-the-fourth day post-partum. The nutrient intake was calculated by using the nutrient content of a food table. The protein composition of the whey was separated by gel electrophoresis and was identified by mass spectrometry and two-dimensional electrophoresis. The results showed that the concentrations of the major protein types in the breast milk were not significantly different between the two groups. The concentrations of the minor protein types varied markedly with the individuals, with higher concentrations in the breast milk of the Thai mothers. There were no significant differences in terms of the energy and protein intake; however, the sources of energy were different. The results indicate that the total protein and lactoferrin concentrations in the breast milk could be predicted by the maternal daily energy and fat intake.

Inactivation of microorganisms and endotoxins by low temperature nitrogen gas plasma exposure.

The plasma of several different gases has shown a sporicidal activity. From these gases, nitrogen gas was most difficult to produce atomic nitrogen radicals. However, these radicals have a high energy, indicating that nitrogen gas plasma could be used to sterilize microorganisms and inactivate endotoxins. The sterilization mechanism of nitrogen gas plasma is the synergistic effect of a high rising-up voltage pulse, UV irradiation and atomic nitrogen radicals. Thus, the target cells were damaged by degradation, which resulted in death. The biological indicator (BI) used in this study was Geobacillus stearothermophilus ATCC 7953 at a population of 1 x 10(6) CFU/sheet. Sterility assurance was confirmed by using the BI. Moreover, endotoxins were successfully inactivated. More than 5 log reduction of endotoxins could be attained with 30 minutes of nitrogen gas plasma exposure. Material functionality influenced by nitrogen gas plasma presented a satisfactory result. No deterioration of polymers could be observed by nitrogen gas plasma exposure.

Characteristic biological activities of lipopolysaccharides from Sinorhizobium and Mesorhizobium.

The biological actions of lipopolysaccharides (LPSs) from Sinorhizobium meliloti, Mesorhizobium loti and Escherichia coli were compared. In biological activities including lethality, production of tumor necrosis factor (TNF)-alpha and nitric oxide (NO), adjuvant action and Limulus activity, LPS from S. meliloti exhibited stronger actions than LPS from M. loti, but had a weaker action than LPS from E. coli. On the other hand, M. loti LPS showed a higher activity to activate human complement than S. meliloti LPS. Further, there was a significant difference in polymyxin B binding between S. meliloti LPS and M. loti LPS, suggesting a difference in the lipid A structure. LPSs from S. meliloti and M. loti seem to exhibit characteristic biological actions that may be dependent on the difference in the lipid A structure.

Lipopolysaccharide biosynthesis-related genes are required for colony pigmentation of Porphyromonas gingivalis.

The periodontopathic bacterium Porphyromonas gingivalis forms pigmented colonies when incubated on blood agar plates as a result of accumulation of mu-oxo haem dimer on the cell surface. Gingipain-adhesin complexes are responsible for production of mu-oxo haem dimer from haemoglobin. Non-pigmented mutants (Tn6-5, Tn7-1, Tn7-3 and Tn10-4) were isolated from P. gingivalis by Tn4351 transposon mutagenesis [Hoover & Yoshimura (1994), FEMS Microbiol Lett 124, 43-48]. In this study, we found that the Tn6-5, Tn7-1 and Tn7-3 mutants carried Tn4351 DNA in a gene homologous to the ugdA gene encoding UDP-glucose 6-dehydrogenase, a gene encoding a putative group 1 family glycosyltransferase and a gene homologous to the rfa gene encoding ADP heptose-LPS heptosyltransferase, respectively. The Tn10-4 mutant carried Tn4351 DNA at the same position as that for Tn7-1. Gingipain activities associated with cells of the Tn7-3 mutant (rfa) were very weak, whereas gingipain activities were detected in the culture supernatants. Immunoblot and mass spectrometry analyses also revealed that gingipains, including their precursor forms, were present in the culture supernatants. A lipopolysaccharide (LPS) fraction of the rfa deletion mutant did not show the ladder pattern that was usually seen for the LPS of the wild-type P. gingivalis. A recombinant chimera gingipain was able to bind to an LPS fraction of the wild-type P. gingivalis in a dose-dependent manner. These results suggest that the rfa gene product is associated with biosynthesis of LPS and/or cell-surface polysaccharides that can function as an anchorage for gingipain-adhesin complexes.

Wall-yielding properties of cell walls from elongating cucumber hypocotyls in relation to the action of expansin.

The wall-yielding properties of cell walls were examined using frozen-thawed and pressed segments (FTPs) obtained from the elongation zones of cucumber hypocotyls with a newly developed programmable creep meter. The rate of wall extension characteristically changed depending on both tension and pH. By treatment of the FTPs with acid, the yield tension (y) was shifted downward and the extensibility (phi) was increased. However, the downward shift of y was greatly suppressed and the increase in phi was partly inhibited in boiled FTPs. The boiled FTPs reconstituted with expansin fully recovered the acid-induced downward y shift as well as the increase in phi. Even under the tension below y, wall extension took place pH dependently. Such extension was markedly slower (low-rate extension) than that under the tension above y (high-rate extension). At a higher concentration (8 M), urea markedly inhibited the creep ascribable to the inhibition of the acid-induced downward y shift and increase in phi. Moderate concentrations (2 M) of urea promoted wall creep pH dependently. The promotion was equivalent to a 0.5 decrease in pH. The promotion of creep by 2 M urea was observed in boiled FTPs reconstituted with expansin but not in boiled FTPs. These findings indicated that the acid-facilitated creep was controlled by y as well as in cucumber cell walls. However, y and phi might be inseparable and mutually related parameters because the curve of the stress extension rate (SER) showed a gradual change from the low-rate extension to the high-rate extension. Expansin played a role in pH-dependent regulation of both y and phi. The physiological meaning of the pH-dependent regulation of wall creep under different creep tensions is also discussed with reference to a performance chart obtained from the SER curves.

The role of wall Ca2+ in the regulation of wall extensibility during the acid-induced extension of soybean hypocotyl cell walls.

We examined the acid-facilitated yielding properties of cell walls of soybean hypocotyls and the effects of Ca(2+) upon the properties by stress-strain analyses using glycerinated hollow cylinders (GHCs) from the elongating regions of the hypocotyls. Stress-extension rate curves of native GHCs showed characteristic changes with pH, all indicating the existence of yield threshold tension (y) as well as wall extensibility (phi), i.e. a downward shift of y and an increase in phi with wall acidification. The acid-induced downward shift of y was inhibited by boiling of GHCs. In contrast, a considerable increase in phi with acidification remained even after boiling. This indicates that phi consists of two components, i.e. heat-sensitive and heat-resistant, both being pH sensitive. A Ca(2+) chelator (Quin 2) dramatically increased phi at a neutral pH. Subsequent addition of Ca(2+) or ruthenium red suppressed the chelator-induced increase in phi. These findings suggest that wall Ca(2+) plays an important role in the regulation of wall extensibility during the acid-induced wall extension by reacting with carboxyl groups of wall pectin.