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Biomedical subjects

W Y Zeng

Publications and source records attributed to W Y Zeng.

10 recordsLinked to original sources
PubMed2002

Purification, molecular characterization and reactivity with aromatic compounds of a laccase from basidiomycete Trametes sp. strain AH28-2.

A recently isolated basidiomycete, Trametes sp. strain AH28-2, can be induced to produce a high level of laccases when grown on a cellobiose-asparagine liquid medium. After induction by kraft lignin, two major isozymes were detected in the fermentation supernatant of the fungus. The principal component laccase A, which accounts for about 85% of the total activity, can be purified to electrophoretic homogeneity by three chromatographic steps: DEAE-Sepharose FF, Superdex-200 and Mono-Q. The solution containing purified laccase is blue in color, and the ratio of absorbance at 280 nm to that at 600 nm is 22. The molecular mass of laccase A is estimated to be 62 kDa by SDS-PAGE, 57 kDa by FPLC, and measured as 58522 Da by MALDI mass spectrum. Laccase A is a monomeric glycoprotein with a carbohydrate content of 11-12% and an isoelectric point of 4.2. The optimum pH and temperature for oxidizing guaiacol are 4.5 and 50 degrees C, respectively. The half-life of the enzyme at 75 degrees C is 27 min. The enzyme shows a good stability from pH 4.2 to pH 8.0. The K(m) values of the enzyme toward substrates 2,2'-azino-bis (3-ethylbenzothazoline-6-sulfonate) (ABTS), guaiacol and 2,6-dimethoxyphenol are 25, 420 and 25.5 microM, respectively, and the corresponding V(max) values are 670, 66.8, and 79 microM min(-1) x mg(-1), respectively. Laccase A activity is strongly inhibited by 0.1 mM NaN(3) or 0.1 mM cyanide. Two units of laccase A alone is able to completely oxidize 100 micromol 2,6-chlorophenol in 6 h. In the presence of 1 mM ABTS and 1-hydroxybenzotriazole, 15.0 U laccase A is able to oxidize 45% and 70% of 50 micromol fluorene in 12 and 18 h, respectively. The laccase A gene was cloned by a PCR method, and preliminary analysis of its sequence indicates 87.0% similarity to the corresponding segment in the phenoloxidase gene from Coriolus hirsutus.

Amino Acid Sequence↗
PubMed2001

[Factors of laccase producing and fermentation conditions by a new white-rot fungus AH28-2].

White-rot fungus AH28-2, a newly isolated strain, produced effectively laccase by induction when grown on a synthetic medium. Aromatic compounds of low molecular weight had an inducing influence on laccase production and its isoenzyme compositions. The using of o-toluidine or syringic acid had the best inducing effect. Cu2+ concentration in medium had distinguished effect on laccase production. Enzyme activity was notably increased by Cu2+ and reached the maximum when Cu2+ final concentration was 5 mumol/L. Mn2+ inhibited the synthesis of laccase. Carbon and nitrogen limitation were not beneficial to laccase synthesis, while high nutrient organic medium was beneficial to the growth of cell and the synthesis of laccase. Using cellobiose as the sole carbon source, the highest level enzyme activity reached 82,923. 7 u/L under the condition of optimum fermentation with ABTS as substrate. This enzyme activity was 2.9-fold higher compared to the reported data on international references in recent years.

Basidiomycota↗
PubMed1993

[Combined use of ondansetron and other anti-emetics to control cisplatin-induced nausea and vomiting].

While ondansetron is effective in the control of nausea and vomiting induced by high dose cisplatin, it has to be given in multiple doses and is very expensive. We designed a regimen of combined use of a single dose of ondansetron and dexamethasone to control acute emesis and combined use of metoclopramide, diphenhydramine and valium to control delayed emesis. The results of this regimen was compared with that of the routine treatment regimen using metoclopramide plus diphenhydramine plus valium. A total of 43 patients were rolled in the cross-over study. Effective control of acute emesis was achieved in 93.6% of the patients with an average of 0.7 emetic episodes. In contrast, effective control of acute emesis was observed in only 18.2% of the patients with an average of 8.1 emetic episodes in those treated with the routine regimen. The regimen increased the emesis control rate by 7.6% and 42.7% on day 1 and 2, respectively as compared to that of repeated administrations of ondansetron alone. The regimen, though not as good as expected, was still better than the routine one for the control of delayed emesis. It deserves recommendation for its better anti-emetic efficacy and lower medical expenses.

Adult↗
PubMed1992

[Anti-emetic effect of ondansetron in cisplatin induced nausea and vomiting--a randomized clinical trial].

The anti-emetic effect of ondansetron in cisplatin induced nausea and vomiting was studied in a randomized cross-over trial in 52 patients. The dose of cisplatin was 80-120 mg/M2 iv drip given in 1-3 days. The patients randomly received ondansetron or our routine anti-emetic regimen in the first cycle of chemotherapy. All the patients were crossed-over to the other anti-emetic regimen on the second cycle of the same cisplatin containing regimen. The results showed that ondansetron was superior to our routine anti-emetic regimen in controlling acute nausea and vomiting. 86% of patients treated with ondansetron and 20.4% treated with the routine regimen had a complete or marked response (O-2 emetic episodes). The mean frequency of vomiting were 1.3 times in ondansetron and 8.0 times in the routine regimen (P less than 0.01). Control of delayed emesis was comparable in the two arms. No patient had neurological symptoms in the ondansetron group whereas 4 patients in the routine group had extrapyramidal symptoms.

Adult↗
PubMed1990

Ontogeny of dopamine D1 receptors in rat forebrain: a quantitative autoradiographic study.

The development of dopamine D1 receptors during the early postnatal period is examined in rat forebrain, using quantitative autoradiography and [3H]SCH 23390 as ligand. Dopamine D1 receptors are present in many regions at birth. In general, regions with the highest densities of D1 receptors in adults have the highest densities of receptors in neonates. For most regions in the forebrain there is a steady increase in the density of D1 receptors, as measured in fmol/mg tissue, from day 1 to day 28 of age. This is most obvious in the regions with the greatest number of receptors, such as the caudate-putamen, the nucleus accumbens, and the olfactory tubercles. The more caudal regions examined in this study had a relatively greater portion of their receptors present at day 1 compared to day 28 than more rostral regions. In general they had about 50% of their receptors present at birth, whereas most regions studied had receptor levels at day 1 about 20% of those found at day 28. In the most anterior regions, the development of receptors was somewhat slower. Receptor number in the frontal cortex region did not begin to increase until about 10 days of age. The present studies indicate that dopamine D1 receptors develop in the forebrain of the rat in a steady pattern. There are no dramatic increases or decreases in receptor number throughout the postnatal period.

Aging↗
PubMed1989

Dopamine D1 receptor development in the rat striatum: early localization in striosomes.

The development of dopamine D1-receptors in rat striatum during the early postnatal period is examined, using autoradiography and [3H]SCH 23390 as ligand. Dopamine D1-receptors are present in striatum at birth and are more dense than in any adjacent region. The receptors are preferentially localized in striosomes and to some extent in a subcallosal streak. The density of D1-receptors in the matrix increases with age so that by two weeks postnatally the striosomal pattern is no longer evident, and the overall dense labelling is the same as seen in adults. Dopamine D1-receptor development seems to take place earlier than that of dopamine terminals but at the same time as or somewhat later than that of acetylcholinesterase. The D1-defined striosomes move from ventrolateral towards dorso-medial striatum with increasing age and from anterior to posterior striatum. This direction is nearly perpendicular to the direction of development of several other markers, including dopamine terminals and D2-receptors. The present studies indicate that for markers appearing in the striosomal compartment there are different patterns of development with respect to time and spatial pattern. Regulation of striatal development by interaction of neuronal systems with one another and with other factors is complex and will require extensive study to clarify the mechanisms involved.

Aging↗
PubMed1988

Ontogeny of dopamine D1 receptors in rat striatum.

The development of dopamine D1 receptors in rat striatum during the early postnatal period is described, using [3H]piflutixol as ligand. Dopamine D1 receptors increase in number from day of birth until about 21 days of age, when they reach adult levels. This increase in number parallels the increase in several other dopamine markers in striatum during the same time period. The increase is reflected in an increase in Bmax of ligand binding to D1 receptors. All other properties of D1 receptors that were examined do not change throughout this developmental period and are essentially the same as those found in adult tissue. These include association and dissociation rates, affinity for piflutixol as determined by kinetic and saturation studies, and pharmacology. These studies provide a biochemical and pharmacological basis for further studies on the ontogeny of dopamine receptors and of striatum and on factors regulating development of this region.

Aging↗
PubMed1987

Nicotine administration to rats: methodological considerations.

The effects of nicotine on normal physiological function are of increasing concern. Preliminary to studies on the effects of prenatal exposure to nicotine, we examined methods of administering nicotine to rats. Drinking water containing nicotine was not palatable to rats and was an unsatisfactory method in our hands, producing weight loss and large decreases in fluid intake. Administration of nicotine in a complete liquid diet produced better results but the data suggest that oral administration of nicotine may interfere with absorption of some nutrients. Osmotic mini-pumps were found to be the best mechanism of nicotine delivery of those tried. There were no significant effects on food or water intake nor on weight gain, particularly when using a short term anesthetic for pump implantation. Plasma nicotine and cotinine levels were directly correlated to dose of nicotine delivered. Plasma nicotine levels similar to levels reported in humans were obtained.

Administration, Oral↗
PubMed1987

[Evaluation of combined chemotherapy including high-dose cisplatin in the treatment of malignant tumors].

The results of 63 patients with advanced malignant tumors treated by combined chemotherapy including high-dose cisplatin (HD-DDP) (single dose 50-100 mg/m2) are reported. The remission rates and duration of the remission for various malignant tumors were: 40% (10 PR out of 25 patients) and 3-8 months for non-small cell lung cancer (NSCLC) treated by PMFV (DDP, MMC, 5FU and VCR) regimen; 87% (4 CR and 9 PR out of 15) and 3-14 months for breast cancer treated by PCMF (DDP, CTX, MTX and 5FU) regimen; 100% (1 CR and 3 PR out of 4) and 3-10 months for testicular cancer treated by PPV (DDP, Pingyangmycin and VCR) regimen; 57% (1CR and 3 PR out of 7) and 5-12 months for malignant melanoma treated by PBDV (DDP, BCNU, DTIC and VCR) regimen; 33% (2 PR out of 6) and 5 months for esophageal cancer treated by PPV regimen. In 6 patients with other malignant tumors, the remission rate was 50% (3 PR). The results show that the combined regimens including HD-DDP in the treatment of breast cancer and NSCLC (remission rate 87% and 40%, respectively) are better than that including low-dose DDP (17% and 7%) (P less than 0.001, P less than 0.01) and that including adriamycin (30% and 13%) (P less than 0.001, P less than 0.05). In the treatment, obvious gastrointestinal reaction, leukopenia, thrombocytopenia and mild functional damage of the liver and kidney were observed.

Adult↗