Mechanism of drug resistance of Pseudomonas aeruginosa / 中国生化药物杂志

Pseudomonas aeruginosa exhibits an inherently reduced susceptibility to most antibiotics compared with most other Gram-negative bacterial species because its low outer membrane permeability and the multiple ways in which P.aeruginosa can become drug-resistant.Pseudomonas aeruginosa has joined the “super bacteria”.Recent researches, using mutant library screening, microarray technology, and mutation frequency analysis have demonstrated that antibiotics themselves can induce very large groups of genes in vivo growth conditions or complex adaptation conditions ( for example, biofilm growth or swarming motility), resulting in resistance as well as new forms of adaptive resistance.

Cloning of cDNAs encoding skin antimicrobial peptide precursors from Chinese brown frogs, Rana chensinensis and determination of antimicrobial, anticancer and hemolysis activity / 生物工程学报

Amphibian skin antimicrobial peptides exhibit a broad spectrum of antimicrobial activity against Gram-positive and Gram-negative bacterium and cytotoxic activity responsible for inhibiting the growth of cancer cells. In this present study, six cDNAs encoding antimicrobial peptide precursors were cloned from the skin of Chinese brown frog, Rana chensinensis by RT-PCR and 3'-RACE procedure and identified as preprotemporin-1CEa, preprotemporin-1CEb, preprotemporin-1CEc, preprobrevinin-1CEa, preprobrevinin-1CEb, and preprochensinin-1, respectively. The nucleotide sequences of cDNA encoding 59-65 amino acid composed of 289-315 bp. Preprotemporin-1CEa, preprotemporin-1CEb and preprotemporin-1CEc are members of temporin family, which usually are short, hydrophobic, and C-terminally alpha-amidated antimicrobial peptides. Preprobrevinin-1CEa and preprobrevinin-1CEb were identified as the members of the brevinin-1 family of antimicrobial peptides since both peptides contain "RANA box" that it's responsible for forming Cys-bridged cyclic heptapeptides at the C-terminal region of peptide. The nucleotide acid sequence and the deduced amino acid Sequence of preprochensinin-1 were not found to be identity with any known amphibian skin defensive peptides, so, preprochensinin-1 was identified as a novel peptide precursor. Four of bioactive peptides: temporin-1CEa, temporin-1CEb, brevinin-1CEa and chensinin-1 were synthesized to investigate their antimicrobial, anticancer and haemolysis activities. The results showed that all of the synthesized antimicrobial peptides in this study inhibited the growth of the Gram-positive bacterium, and exhibited the anticancer activity against the growth of MCF-7 cells and HeLa cells. Analysis of the R. chensinensis bioactive peptides and their gene expression will be beneficial for preservation of this species.

Anticoagulant Activities of Polysaccharides from the Heads of Rana temporaria chensinensis / 中药新药与临床药理

Objective To investigate the anticoagulant effect of polysaccharides from the heads of Rana temporaria chensinensis(Chinese Forest Frogs). Methods In-vitro experiments were applied to test the effect of polysaccharides on recalcification time, prothrombin time, thrombase time , the activities of thrombin, hydrolyzing fibrin content, activated fibrin dissolve zymogen and blood clotting.. In the in-vivo experiment, bleeding time was measured by cutting mouse tail and clotting time was measured by glass sheet method. Results The polysaccharides from the heads of Chinese Forest Frogs had an obvious anticoagulant effect in a dose-effect manner, but had on thrombolytic action. It could prolong the bleeding time and the clotting time in vivo. Condusion The polysaccharides from the heads of Chinese Forest Frogs have the anticoagulatant activities in vitro and in vivo.

STUDY ON ANTIOXIDATIVE AND ANTITUMOR EFFECT OF SELENIUM CONTAINING POLYSACCHARIDE IN GANODERMA LUCIDUM IN MICE / 营养学报

Objective: To investigate the effects of selenium containing polysaccharide from Ganoderma lucidum on SOD, GSH Px activity, MDA content in blood and liver and anti tumor effect in tumor bearing mice, and relationship between antioxidative and anti tumor effect. Methods: The tumor bearing BALB c mice were injected with 2.5 g/L? 5.0 g/L and 10.0 g/L SeGLP 1 respectively for 14 days. Weight of tumor, both SOD and GSH Px activities and MDA content of blood and liver were determined. Results: SeGLP 1 could significantly inhibit the growth of Hca f, maximal inhibition rate was 44%, SeGLP 1 significantly increased SOD, GSH Px activity, decreased MDA content of blood and liver in tumor bearing mice. Conclusion: The anti tumor effect of SeGLP 1 may be due to enhanced antioxidative capacity in tumor bearing mice.