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Biomedical subjects

Y J Yuan

Publications and source records attributed to Y J Yuan.

8 recordsLinked to original sources
PubMed2006

Optimization of a medium for enhancing nicotine biodegradation by Ochrobactrum intermedium DN2.

AIMS: To optimize a medium for nicotine degradation by Ochrobactrum intermedium DN2 in presence of yeast extract, glucose and Tween 80 using response surface methodology (RSM). METHODS AND RESULTS: In this study, the effects of yeast extract, glucose and Tween 80 on nicotine degradation were investigated in flasks using a novel nicotine-degrading bacterium, O. intermedium DN2. A full factorial central composite design was applied in the design of experiments and in the analysis of the experimental data. The results showed that the most significant variable influencing nicotine degradation was yeast extract, followed by glucose, and then Tween 80. Moreover these three factors interacted with each other and combined to produce positive effects on nicotine degradation. The experimental data also allowed the development of an empirical model (P < 0.0001) describing the inter-relationship between independent and dependent variables. By solving the regression equation, the optimal values of the variables were determined as: yeast extracts 0.094%, glucose 0.101% and Tween 80 0.080%. Using the medium obtained, about 1,220 mg l(-1) of nicotine was degraded (95.55%) within 10 h at the specific biodegradation of 116.59 mg l(-1) h(-1) in 30-l bioreactor containing 25-l tobacco extract. CONCLUSIONS: An optimal medium of nicotine degradation by the strain DN2 was obtained. SIGNIFICANCE AND IMPACT OF THE STUDY: RSM proved to be reliable in developing the model, optimizing factors and analysing interaction effects. The results provide better understanding on the interactions between yeast extract, glucose and Tween 80 for nicotine biodegradation.

Biodegradation, Environmental↗
PubMed2001

[Effects of fungal elicitor on cell status and taxol production in cells suspension cultures of Taxus chinesis var. mairei].

Effects of fungal elicitor on cell redox status and taxol production were studied in suspension cultures of Taxus chinesis var. mairei in the late exponential stage. The results show that fungal elicitor induced oxygen burst, changes of the cell redox status, alkalinization of medium and the fluctuation of the activity of redox enzymes with a sequence. The content of protein representing the quantity of enzymes increased. The activity of SOD increased quickly after treatment by fungal elicitor and that of POD could be kept at a higher level in contrast to the control. The activity of CAT was inhibited at first and followed by an obvious increase, while the activity of PAL was promoted. The taxol yield was 5 folds of the control, reaching to 67 mg/L.

Antineoplastic Agents, Phytogenic↗
PubMed2000

[Cloning of taxadiene synthase cDNA from the cell line of Taxus cuspidata].

Taxadiene synthase plays an important role in taxol biosynthesis. RT-PCR was used for cloning taxadiene synthase cDNA fragment from the cells of T. cuspidata. The cDNA was cloned into vector pGEM and transformed to E. coli J M109. The cloned cDNA named pCBMZ was further confirmed by Southern blotting assay and was sequenced. The result showed that taxadiene synthase cDNA of Taxus cuspidata was highly homologous with that of Taxus brevifolia.

Base Sequence↗
PubMed2000

[Study on taxol release in the two-liquid-phase cultures of Taxus cuspidata].

Effects of rare earth compound (ammonium sulphate), organic solvents(oleic acid and dibutylphthalate) and the integrated function of the rare earth compound and organic solvents were studied on taxol release in the Taxus cuspidata suspension cultures. And then effects of different organic solvents(paraffin, organic acid, alcohol and ester), their volumetric fraction and phase toxicity were studied on taxol release in the two-liquid-phase cultures of Taxus cuspidata. The results showed that the addition of the rare earth compound or the organic solvents could strengthen obviously taxol release, especially the organic solvents. But the addition of the rare earth compound could not strengthen further taxol release in the twoliquid-phase cultures of Taxus cuspidata. Therefore the organic solvents were very good permeabilizing reagents, which could enhance obviously secondary metabolite in the twoliquid-phase cultures of plant cells. Release percentage of taxol was increased into more than 75% from 40% of the control.

Antineoplastic Agents, Phytogenic↗
PubMed2000

[Study on the effects of salicylic acid on taxol biosynthesis].

The influence of salicylic acid on the production of taxanes in plant cell culture was studied. Experimental results showed that addition of salicylic acid at concentration of 0.1 mg/L could enhance the production of taxol to three-fold. The concentration of 10-DAB and baccatin III was also increasing while taxol concentration increases under salicylic acid elicitation. On the basis of the kinetic analysis about the simplified taxol biosynthesis pathway, a probable reason that salicylic acid improves the rate of 10-DAB producing reaction was introduced. The results above can direct its inducing mechanic research and provide the basis of multiple-elicitors synergism. The concentration of taxol arrives at 39 mg.L-1 induced by salicylic acid with silver nitrate, being 150 percent of the sum of taxol obtained under elicitation of salicylic acid and silver nitrate respectively.

Antineoplastic Agents, Phytogenic↗
PubMed1999

[Testosterone induction of metallothionein in accessory genital organs of male domestic cats].

Orchidectomy of cats resulted in a decrease of metallothionein (MT) in the dorsolateral and ventral lobes of the prostate and in the urethral gland to 21.2% (P<0.01), 88.4% (P>0.05) and 18.5% (P<0.01) of those of intact domestic cats respectively. MT content in the dorsolateral lobe and urethral gland was not restored in orchidectomized cats injected with sesame oil. After injection of a single subcutaneous dose of 10 microg/kg bw of testosterone (T) for 3 d in succession, the MT contents in the two glands were restored respectively to 69.3% and 59.4% of the intact cats. With an increase of T dose to 5, 10, 15, 20, 25 microg/kg bw, plasma T and MT contents in the dorsolateral lobe of prostate and urethral gland increased accordingly. Plasma T concentrations were positively correlated with MT contents in the dorsolateral lobe of prostate and urethral glands (P<0.01). Thus biosynthesis of MT in the dorsolateral lobe of prostate or in urethral gland could be induced by a stimulatory dose of T of 20 microg/kg bw.

Animals↗