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Objective@#To investigate the mechanisms by which D-methionine (D-Met) eradicates Porphyromonas gingivalis biofilms by suppressing cyclic dimeric GMP (c-di-GMP) levels.@*Methods @#Cell viability, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured to determine the effective concentrations of D-Met, which were subsequently used in the following experiments. During the P. gingivalis biofilm formation inhibition experiment and the mature biofilm disassembly experiment, biofilm biomass, exopolysaccharide (EPS), biofilm morphology, integrity of the cell membrane, and the level of c-di-GMP were determined. @*Results @# D-Met < 40 mmol/L was biocompatible. During the biofilm formation inhibition and mature biofilm disassembly experiments, D-Met ≥ 20 mmol/L decreased the biofilm biomass and the production of EPS. SEM analysis showed that the extracellular matrix and bacterial density were drastically reduced by D-Met ≥ 20 mmol/L. TEM detection showed that 35 mmol/L D-Met ruptured the cell membrane during biofilm formation and increased the permeability of the cell membrane in the disassembly phase of mature biofilms. C-di-GMP levels decreased with increasing concentrations of D-Met in a concentration-dependent manner.@* Conclusion @# D-Met ≥ 20 mmol/L could eradicate P. gingivalis biofilms by suppressing c-di-GMP levels.
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Objective To evaluate the protective effects of oral administration of D-methionine tablets on noise-induced hearing loss.Methods A total of 203 volunteers were recruited and randomly divided into two groups:experimental group (n=113)and control group (n=90).The subjects in the experimental group received oral administration of D-methionine tablets(1 500 mg/day)and those in the control group received placebo for 3 days before impulse noise exposure.The routine audiometric evaluation and ABR testing were performed and recor-ded 1 day and 7 days post- noise exposure.The statistical analysis was carried out with SPSS 11.0.ResuIts The changes of hearing in all participators were observed after noise exposure.The results were as follow:The hearing thresh-olds at three time points were 40.5±9.3,51.7±12.3,44.1±11.4 dB nHL in experimental group and 41.5±8.9,62.4± 13.7,47.6±12.5 dB nHL in control group,respectlvely;the ABR I-V IPLs at three time points were 3.72±0.21 ms, 3.99±0.36 ms,3.82±0.25 ms in experimental group,while 3.71±0.22 ms,4.45±0.37 ms,3.85±0.34 ms in control group,respectively.There were statistically significant differences between the two groups.ConcIusion The oral adminis-tration of D-methionine tablets pre noise exposure can protect against noise-induced hearing loss.
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Objectives: To study the effect of D-methionine on gastric cancer and its mechanism. Methods: We used a medium with D-methionine to culture six gastric cancer cell lines. The medium with L-methionine acted as control to culture cells. The proliferation of cells was detected by MTT. Apoptotic rates and cell cycle were detected by FMC. Results: Absorbance of all cell lines was significantly lower than control (P0.05). KATO-Ⅲ cells stayed more in G 0 /G 1 phase (P
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Objective: To investigate the amino acids metabolism of gastric cancer cells in D-methionine(D-Met) medium.Methods: Six gastric cancer cell lines were respectively cultured with L-methionine(L-Met),D-Met,or without methionine(Met-) medium.Amino acids profile of every culture medium was measured by HPLC after 5 days. Results: Methionine concentration of six cell lines in Met medium was significantly lower than that in L-Met or D-Met medium(P
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Objective:To study the expression of D-amino acid oxidase(DAO) in gastric cancer cells and gastric mucosa cells. Methods:The expression of DAO was detected in seven gastric cancer cell lines and a normal gastric mucosa cell line GES-1 by real-time quantitative PCR and in tumor tissues and normal gastric mucous tissues of 46 patients with gastric cancer by RT-PCR.The liver and kidney tissues of nude mouse acted as positive controls.Results:DAO was expressed in the liver and kidney tissues of nude mouse,and DAO expression in kidney tissue was higher than that in liver tissue.DAO was not detected in seven gastric cancer cell lines and the normal gastric mucosa cell line GES-1.Except one tumor tissue sample,DAO was not detected in other gastric cancer tissues and all normal mucosa tissues.Conclusion:DAO was not expressed in gastric cancer cells and gastric mucosa cells.The nutritional treatment of D-Met in place of L-Met could avoid the disadvantage of methionine starvation to important organs,such as liver and kidney.