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The effects of three diosgenyl saponins isolated from Paris polyphylla on the immuno-stimulating activity in relation to phagocytosis, respiratory burst, and nitric oxide production in mouse macrophage cells RAW 264.7 have been investigated. Our results showed that all three diosgenyl saponins significantly enhanced phagocytic activity that increased with the concentration of saponins to reach a maximum, and then tended to decrease with higher concentrations. Saponins with sugar moiety directly induced respiratory burst response in RAW 264.7 cells that increased with the concentrations and reached a maximum, then decreased with higher concentrations after 2-h incubations, however, diosgenin had no PMA-triggered respiratory burst response. Treatment of RAW 264.7 cells with saponins with sugar moiety for 24-h caused a significant increase in the production of nitric oxide, while diosgenin had no effect at all. Consequently, relationship between molecular structures of three diosgenyl saponins and their immunomodulatory activities was discussed, and a possible mechanism of immuno-stimulating function of diosgenyl saponins was accordingly explored.

A new phosphorylated linear nitrone N-(4-hydroxybenzyliene)-1-diethoxyphosphoryl-1-methylethylamine N-oxide (4-HOPPN) was synthesized, and its X-ray structure was determined. The spin trapping ability of various kinds of free radicals by 4-HOPPN was evaluated. Kinetic study of decay of the superoxide spin adduct (4-HOPPN-OOH) shows the half-life time of 8.8 min. On the basis of the X-ray structural coordinates, theoretical analyses using density functional theory (DFT) calculations at the B3LYP/6-31+G(d,p)//B3LYP/6-31G(d) level were performed on spin-trapping reactions of superoxide radical with 4-HOPPN and PBN and three possible decay routes for their corresponding superoxide adducts. The comparative calculations on the spin-trapping reactions with superoxide radical predicted that both spin traps share an identical reaction type and have comparable potency when spin trapping superoxide radical. Analysis of the optimized geometries of 4-HOPPN-OOH and PBN-OOH reveals that an introduction of the phosphoryl group can efficiently stabilize the spin adduct through the intramolecular H-bonds, the intramolecular nonbonding attractive interactions, as well as the bulky steric protection. Examination of the decomposition thermodynamics of 4-HOPPN-OOH and PBN-OOH further supports the stabilizing role of the phosphoryl group to a linear phosphorylated spin adduct.

The oxygen-evolving complex (OEC) of Mn-depleted photosystem II (PSII) can be reconstituted in the presence of exogenous Mn or a Mn complex under weak illumination, a process called photoactivation. Synthetic Mn complexes could provide a powerful system to analyze the assembly of the OEC. In this work, four mononuclear Mn complexes, [(terpy)2Mn(II)(OOCH3)] x 2 H2O (where terpy is 2,2':6',2''-terpyridine), Mn(II)(bzimpy)2, Mn(II)(bp)2(CH3CH2OH)2 [where bzimpy is 2,6-bis(2-benzimidazol-2-yl)pyridine] and [Mn(III)(HL)(L)(py)(CH3OH)]CH3OH (where py is pyridine) were used in photoactivation experiments. Measurements of the photoreduction of 2,6-dichorophenolindophenol and oxygen evolution demonstrate that photoactivation is more efficient when Mn complexes are used instead of MnCl2 in reconstructed PSII preparations. The most efficient recoveries of oxygen evolution and electron transport activities are obtained from a complex, [Mn(III)(HL)(L)(py)(CH3OH)]CH3OH, that contains both imidazole and phenol groups. Its recovery of the rate of oxygen evolution is as high as 79% even in the absence of the 33-kDa peptide. The imidazole ligands of the Mn complex probably accelerate P680*+ reduction and consequently facilitate the process of photoactivation. Also, the strong intermolecular hydrogen bond probably facilitates interaction with the Mn-depleted PSII via reorganization of the hydrogen-bonding network, and therefore promotes the recovery of oxygen evolution and electron transport activities.

A P. aeruginosa strain PA68 isolated from the sputum of a patient suffering from bronchiectasis was used as the recipient strain. Optimum conditions including growth stage of the strain, electroshock voltage, concentration and preservation of competent cell were defined for the electroporation of PA68 with plasmid pSMC28. It was showed that the highest transformation efficiency was up to 1.68 x 10(3) CFU/microgram DNA under the optimum conditions in which the competent cells were collected at logarithmic growth phase (OD(540) = 0.7-0.8) and concentrated to about 10(11) cells/ml, the mixture of the competent cells and plasmid pSMC28 was eletroporated at 2.6 kV. With this optimal condition, Mu transponson complexes have been successfully transformed into P. aeruginosa strain PA68 and the obtained efficiency was 2.47 x 10(4) CFU/microgram DNA. This is the first time to electroporate Mu transposon complexes into Pseudomonas spp. The artificial Mu transposons could integrate into bacterial genomes at a single site randomly. Then the phenotype change was the result of the gene inactivation caused by Mu transposon insertion. That will be very helpful for the study of genomic function of Pseudomonas spp.

Objective: To study the pathogens in community-acquired pneumonia (CAP), especially the prevalence of atypical pathogens., Methods: A prospective study was performed on 103 consecutive adult patients with CAP between November 2001 and June 2002. Antibodies of the paired serum samples to Mycoplasma pneumoniae, Legionella pneumophilia, and Chlamydia pneumoniae were detected. The P1 adhesion gene of Mycoplasma pneumoniae and the 16S ribosome gene specific for Chlamydia pneumoniae were detected with polymerase chain reaction (PCR). Legionella antigen in urine was detected using enzyme immunoassay (EIA) method. Sputum samples were collected for culture, and bacteria were isolated and identified using conventional methods., Results: The etiology of CAP was identified in 50 (48.5%) patients. The distribution of causal agents was as follows: Mycoplasma pneumoniae in 23 (22.3%) cases, Legionella pneumophilia 3 (2.9%), Chlamydia pneumoniae 2 (1.9%), streptococcus pneumoniae 12 (11.7%), Haemophilus influenzae 9 (8.7%), and Klebsiella pneumoniae 7(6.8%). In 6 patients (5.8%) more than one causal agent were found, among them Mycoplasma pneumoniae was found in 5 cases with mixed infections., Conclusions: Atypical pathogens especially Mycoplasma pneumoniae have an important role in CAP. Streptococcus pneumoniae and Haemophilus influenzae remain the most common bacteria, and mixed infection should not be ignored.