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L Ruan

Publications and source records attributed to L Ruan.

At least 19 recordsLinked to original sources
PubMed2006

Little Egrets (Egretta garzetta) and trace-metal contamination in wetlands of China.

The rapidly developing Asian countries may face threatening environmental contamination, that however remains largely unassessed. We studied persistent trace elements in three wetlands, Poyang Lake, relatively unpolluted, and Tai Lake, and Pearl River Delta, selected as hotspots of pollution in Central China. We adopted as indicator the Little Egret, a widespread colonial waterbird, and during 1999 and 2000 we collected and analysed the same samples as for a parallel study we conducted in Pakistan, e.g. eggs, body feathers of chicks, prey spontaneously regurgitated by the chicks, and sediments at the areas most used by foraging egrets. The levels of trace-metals at our three study areas were similar, or within the range, of those found in the few other studies for East Asia, with few exceptions. The concentrations of the various elements were below the threshold that may affect the survival or reproduction of the birds, and even the highest concentrations relative to background, i.e. Se in eggs, and Hg in feathers at Pearl Delta, do not pose toxic hazards. In sediments, the levels of trace elements were lower than the critical levels assumed for contaminated soil, except for alarming high levels of As at Poyang. These results do not confirm our expectation, that Poyang was relatively uncontaminated, while Tai and Pearl were polluted. Although trace metal concentration differed significantly among the three study areas, these differences were minor and were not consistent among elements and samples. The bioaccumulation ratios from sediments through prey, feather and egg, were consistent with our previous findings for Pakistan. Only Hg exhibited high bioaccumulation, while Se and Zn had low accumulation, and the other elements no accumulation. This reasserts that feathers of predators such as egrets, may be more sensitive indicators of environmental contamination for the elements subject to bioaccumulation, whereas the sediments or the organisms low in the food chain are better indicators for the other elements.

Animals↗
PubMed2006

Vegetative insecticidal protein enhancing the toxicity of Bacillus thuringiensis subsp kurstaki against Spodoptera exigua.

AIMS: The objective of this work was to enhance the insecticidal activity or widen the pesticidal spectrum of a commercial Bacillus thuringiensis strain YBT1520. METHODS AND RESULTS: A vegetative insecticidal protein gene vip3Aa7, under the control of its native promoter and cry3A promoter, was subcloned into B. thuringiensis acrystalliferous BMB171 to generate BMB8901 and BMBvip respectively. It was found that the amount of Vip3Aa7 protein produced by BMBvip was 3.2-fold more than that produced by BMB8901. Therefore, the vip3Aa7 gene under the control of cry3A promoter was transformed into strain YBT1520. The toxicity of the resulting strain BMB218V against Spodoptera exigua was 10-fold more than that of YBT1520, and that the toxicity of BMB218V against Helicoverpa armigera retained the same level as that of strain YBT1520. CONCLUSIONS: Strain YBT1520 obtained high toxicity against S. exigua after it was transformed and expressed the foreign vip3Aa7 gene. SIGNIFICANCE AND IMPACT OF THE STUDY: Commercial B. thuringiensis strain YBT1520 has high toxicity against H. armigera and Plutella xylostella, but almost no activity against S. exigua, which is a major crop pest in China. This work provides a new strategy for widening the activity spectrum of B. thuringiensis against agriculture pests.

Animals↗
PubMed2006

[Codon usage of Chinese hamster ovary cells.].

BACKGROUND: To investigate the optimal codons of dihydrofolate reductase (dhfr) minus Chinese hamster ovary cells (CHO dhfr-). METHODS: A cDNA library of CHO dhfr- containing high abundence mRNA was constructed and protein-coding sequences were obtained after identification and analysis. Codon frequence of CHO dhf- was compared with that of Chinese hamster in CUTG database. Then codon usage variation among cDNA was investigated using correspondence analysis (COA). RESULTS: Fifty qualified cDNAs from CHO dhfr- were selected, which encodes proteins of high abundence. Comparing with the codon frequence of Chinese hamster, the highest frequence of synonymous codons for amino acids in CHO dhfr- cells were the same as Chinese hamster except that of Arg and Pro. This method of COA identifies the first main factor which can account for the largest fractions (14.7%) of variation among cDNAs. Twenty-two synonymous codons were identified as the optimal codons of CHO cell. CONCLUSION: CHO dhfr- cell has its own optimal codons, it is suggested that codon bias is one of reasons for functional diversity of different mammal cells and it is an effective stratagy to modification of the codon usage of the foreign gene according to the optimal codons of CHO dhfr- to increase the production of foreign gene.

Animals↗
PubMed2005

Cloning and expression of mel gene from Bacillus thuringiensis in Escherichia coli.

Previous work from our laboratory has shown that most of Bacillus thuringiensis strains possess the ability to produce melanin in the presence of L -tyrosine at elevated temperatures (42 degrees C). Furthermore, it was shown that the melanin produced by B. thuringiensis was synthesized by the action of tyrosinase, which catalyzed the conversion of L -tyrosine, via L -DOPA, to melanin. In this study, the tyrosinase-encoding gene (mel) from B. thuringiensis 4D11 was cloned using PCR techniques and expressed in Escherichia coli DH5 alpha. A DNA fragment with 1179 bp which contained the intact mel gene in the recombinant plasmid pGEM1179 imparted the ability to synthesize melanin to the E. coli recipient strain. The nucleotide sequence of this DNA fragment revealed an open reading frame of 744 bp, encoding a protein of 248 amino acids. The novel mel gene from B.thuringiensis expressed in E. coli DH5 alpha conferred UV protection on the recipient strain.

Bacillus thuringiensis↗
PubMed2002

Expression of the mel gene from Pseudomonas maltophilia in Bacillus thuringiensis.

AIMS: The objective of this work was to express a novel mel gene, responsible for melanin formation, in Bacillus thuringiensis. METHODS AND RESULTS: A novel mel gene from Pseudomonas maltophilia was sub-cloned into B. thuringiensis using a shuttle vector plasmid and electroporation. Results revealed that the mel gene was expressed under the control of the CryIIIA promoter in B. thuringiensis and conferred u.v. protection on the recipient strain. CONCLUSIONS: The novel mel gene from Ps. maltophilia expressed in B. thuringiensis conferred u.v. protection on the recipient strain. SIGNIFICANCE AND IMPACT OF THE STUDY: Products containing B. thuringiensis for pest control are sensitive to u.v. degradation. As melanin has the ability to act as a u.v. absorber, a recombinant B. thuringiensis strain producing melanin provides a new stability for B. thuringiensis preparations.

Bacillus thuringiensis↗
PubMed2001

[Organochlorine residues in eggs of night heron breeding in Yuantouzhu, Wuxi and their functions as bioindicator].

This study analyzed chlorinated pesticides in eggs of night heron breeding in Yuantouzhu, Tai lake. The HCH isomers, DDT, DDD, DDE, endrine and heptachlor epoxide were detected out in egg samples. The residue level and the percent of detection of beta-HCH and p,p'-DDE were significantly high. The mean value of p,p'-DDE was 0.906 microgram/g dry weight. Most of the chlorinated pesticides in samples from Wuxi were higher than those of Gongqing city, Jiangxi province. Oppositely, the hatching rate of night heron egg in Wuxi region was lower than that in Gongqing city. It may be related to the difference of DDE residual levels. Using organochlorine residue in eggs of water-fowls as an indicator for environmental quality assessment is feasible.

Animals↗
PubMed2001

[Chromosome aberration and carcinogenicity of CHO dhfr- cells transformed by plasmid containing S+ and Pre S1 of fusion gene of hepatitis B virus].

OBJECTIVE: To investigate the chromosome aberrations and carcinogenicity of CHO-dhfr- cell induced by integration of plasmid containing S+ and Pre S1 fusion gene of hepatitis B surface antigen (HBsAg). METHODS: The plasmid pCHBSS1G was constructed with S+ Pre S1 of HBsAg. CHO-dhfr- cells were transformed with this recombinant plasmid DNA and CHO cells lines with integrated DNA were cloned and named GdSS118. The GdSS1 18 cell lines secreting the S+ Pre S1 fusion protein of HBsAg at high level were developed by screening in increased concentration of MTX and MSX in cultured media. To make sample of cells chromosome, the cells integrated DNA were subcutaneously injected into nude mouse. RESULTS: The CHO-dhfr- cell lines integrated with S and Pre S1 fusion protein of HBsAg were developed and named GdSS1-18 cell lines. The frequencies and type of chromosome aberrations of the GdSS1-18 cell lines with different passage generations were 11%, 56% and 29%, respectively, while that of the control CHO-dhfr- cell lines was 6%. There was no change in the mode of chromosomes, both cell lines having 20 chromosome s. Both cell lines were non-oncogenic in nude mouse. CONCLUSIONS: The chromosome aberration of CHO-dhfr- cells with integrated DNA were obviously higher than that of the original CHO-dhfr- cells without integrated DNA. Both cell lines were non oncogenic in nude mouse.

Animals↗
PubMed2001

[The recombinant vaccinia viruses expressing HPV type 16 wild or mutant E7 protein elicit immunity against tumor cells in mice].

OBJECTIVE: To select mutants of HPV 16 E7 suitable for vaccine development. METHODS: Several recombinant vaccinia viruses (VwE7, VmE7-1, and VmE7-2) expressing wild E7 or its mutants, ME7-1 (24G26G) and ME7-2 (24G26G91G) respectively, were employed to study their antigenicity and anti tumor activity. RESULTS: Both VmE7-1 and VwE7 could elicit cytotoxic T lymphocytes (CTL)and protect mice against tumor cells challenge, but VmE7-2 could not induce the immune reactions compared with VmE7-1 and VwE7. CONCLUSIONS: It suggested that ME7-1 could be used to develop a therapeutic vaccine for cervical cancer.

Animals↗
PubMed1997

Binding of vanadate to human erythrocyte ghosts and subsequent events.

Spectroscopic techniques were used to investigate the interaction between vanadate and human erythrocyte ghosts. Direct evidence from 51 V nuclear magnetic resonance (NMR) studies suggested that the monomeric and polymeric vanadate species may bind to the anion binding sites of band 3 protein of the erythrocyte membrane. The results of 51V NMR studies and the quenching effect of vanadate on the intrinsic fluorescence of the membrane proteins indicated that in the low concentration range of vanadate (< 0.6 mM), monomeric vanadate binds mostly to the anion sites of band 3 protein with the dissociation constant close to 0.23 mM. The experiments of sulfhydryl content titration by the method of Ellman and residue sulfhydryl-labeled fluorescence spectroscopies clearly displayed that vanadate reacts directly with sulfhydryl groups. The appearance of the anisotropic election spin resonance (ESR) signal of vanadyl suggests that a small (c.3%) amount of vanadate was reduced by sulfhydryl groups of membrane proteins. The fluidity and order of intact ghost membrane were reduced by the reaction with vanadate, as shown by the ESR studies employing the protein- and lipid-specific spin labels. It was concluded that although vanadates mainly bind to band 3 protein, a minor part of vanadate may oxidize the residue sulfhydryl groups of membrane proteins, and thus decrease the fluidity of erythrocyte membrane.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1997

[Construction of recombinant vaccinia virus expressing HSV-2 gD gene as live recombinant vaccine strain].

We had reported that the recombinant vaccinia virus expressing glycoprotein D of herpes simplex virus type 2 (HSV-2 gD) protected mice against lethal HSV-2 challenge. Following the succeed in animal model, we continue the research to construct the recombinant vaccinia virus expressing HSV-2 gD gene as live recombinant vaccine strain in strict accordance with the guideline for human vaccine research. A PCR-modified HSV-2 gD gene was inserted into the plasmid pJSB1175, under the control of P7.5K early/late promoter of vaccinia virus. The recombinant plasmid was used, with lipofectin reagent, to transfect 2BS cells which had been infected by wild type of TK+ vaccinia virus (Tian Tan 761 strain). The recombinant vaccinia virus harboring HSV-2 gD gene was selected out by using in situ hybridization employing 32P-1a-belled HSV-2 gD fragment as probe, together with three cycles of plaque purification. Dot and Southern blot confirmed HSV-2 gD gene had been integrated into the TK region of vaccinia virus genome, as expected. Indirect immunofluorescent assay using anti-HSV-2 gD monoclonal antibody showed HSV-2 gD was expressed effectively in the recombinant virus infected cells.

Animals↗
PubMed1996

Campomelic syndrome--laryngotracheomalacia treated with single-stage laryngotracheal reconstruction.

The campomelic syndrome is a rare osteochondrodysplasia which frequently leads to early death from pulmonary insufficiency. We describe a patient with anatomic compromise of the upper airway due to diffuse laryngotracheomalacia and a moderate subglottic stenosis, treated successfully with single-stage laryngotracheal reconstruction using a rib graft. To our knowledge this has not been previously described. A review of the current literature is included.

Airway Obstruction↗
PubMed1995

First EBV vaccine trial in humans using recombinant vaccinia virus expressing the major membrane antigen.

In the absence of a truly representative animal model, the question of whether EBV-related diseases can be prevented by a vaccine has been studied for the first time in humans. A live recombinant virus based on the licensed vaccinia strain Tien Tan, expressing under the 11K vaccinia promoter the major EBV membrane antigen BNLF-1 MA (gp 220-340), was constructed and tested in three different human populations: EBV-positive and vaccinia-virus-exposed adults; EBV-positive, non-vaccinia-virus-exposed juveniles; and EBV and vaccinia virus-naive infants. No significant titre variations for EBV were observed in the adults, but EBV-neutralising titres increased in the vaccinated juveniles, while antibodies to VCA of EBV remained unchanged. All nine vaccinated infants developed antibodies to MA (membrane antigen) with neutralising properties in vitro; three of these infants were infected by EBV via natural routes over a period of 16 months after vaccination and all ten unvaccinated control infants became infected. It has been shown for the first time that protection against and/or delay of EBV infection by the natural route is possible in humans and that live vaccinia vectors can be used and are efficacious.

Adult↗
PubMed1994

Ruan et al. reply.

Explore the source record for details and available documents.

Journal Article↗
PubMed1994

The relationship of dietary animal protein and electrolytes to blood pressure: a study on three Chinese populations.

The relationship of diet to blood pressure was studied in a total of 705 men and women aged 40-59 from three Chinese population samples having different mean blood pressure and dietary sodium and animal protein intake. Two groups were farmers from Shanxi in northern China, and Guangxi in southern China, and the third were fishermen from Zhejiang, eastern China. Three 24-hour dietary recalls were done for each participant. Serum and overnight urine amino acids were measured in random subsamples. Determination of electrolytes in three 24-hour urine specimens was done in an additional sample of 59 men in each population. Results of multiple or stepwise regression showed: 1) in the pooled group, individual intake of sodium was positively associated with systolic blood pressure; 2) when stratifying by median calcium intake, a positive association of dietary sodium or sodium/potassium was found only in the group with calcium intake lower than the median; 3) daily intake of animal protein, urinary sulphate and certain serum and urine amino acids formed from protein metabolism, were inversely associated with blood pressure.

Adult↗
PubMed1993

Cloning and structural-functional studies for 7.5k promoter of Tiantan strain of vaccinia virus.

The 7.5k promoter of vaccinia virus Tiantan strain has been cloned by DNA polymerase chain reaction (PCR) method. Results of DNA sequencing analysis showed that in comparison with P7.5k of WR strain, three site mutations and 7 bp of natural deletion existed in the 155 bp fragment of P7.5k of Tiantan strain; four of 7 base pairs deleted were in the late transcriptional initiation region. Although the total mutation rate was high to 6.45%, these two 7.5k promoters of Tiantan strain & WR strain were all early-late promoters and not obviously different in their activities and functional phases. The results above confirmed further that it is a mechanism to keep their genetic stability that some genes of vaccinia virus have multiple transcriptional initiation sites and produce many mRNA with heterologous 5' ends.

Base Sequence↗