Biomedical subjects

Xudong Zhang

Publications and source records attributed to Xudong Zhang.

26 records · Page 2Linked to original sources

PubMed2003

[Effect of different cultivation practices on Fe and Cd content in iron plaque outside rice root and Cd content in rice root].

The effects of different cultivation practices-traditional flooding (TF), film mulching (FM), straw mulching (SM), and wetting cultivation (WC)-on Cd concentrations in Indica and Japonica roots and on Cd and Fe concentrations in iron plaque outside the roots were studied at different growth stages (tillering, booting, filling and harvest) with a Cd-polluted soil. The results showed that in all practices, the mean Fe concentration in iron plaque and the mean Cd concentration in roots of Japonica at tillering stage were 6.37 mg.mg-1 and 25.49 mg.kg-1, and greater than those of Indica, which were 4.52 mg.mg-1 and 16.37 mg.kg-1 respectively; at booting stage, the mean Fe and Cd concentrations in iron plaque and the mean Cd concentrations of Japonica were 1.60, 16.35 and 54.68 mg.kg-1, and greater than those of Indica, which were 1.06 mg.mg-1, 9.56 and 43.31 mg.kg-1, respectively; at filling stage, the Fe concentrations in iron plaque of Japonica in SM and WC were 0.89 and 1.00 mg.mg-1, and those of Indica were 0.63 and 0.30 mg.mg-1; in all practices, the mean Cd concentrations in iron plaque and root of Japonica were 15.23 and 73.68 mg.kg-1, and those of Indica were 3.46 and 52.38 mg.kg-1; at harvest stage, the Fe concentration in iron was plaque of Indica in TF was 1.21 mg.mg-1 and that of Japonica was 0.65 mg.mg-1, but that of Japonica in SM was 0.94 mg.mg-1 and that of Indica in SM was 0.55 mg.mg-1; the Cd concentration in iron plaque of Japonica in WC was 7.96 mg.kg-1, and that of Indica was 5.09 mg.kg-1; the mean Cd concentration in root of Japonica was 54.53 mg.kg-1 and that of Indica was 35.91 mg.kg-1 in all practices.

Cadmium↗

PubMed2003

[The contribution of maize and soybean to N2O emission from the soil-plant system during seedling stage].

To fractionate the contribution of plant to N2O emission from soil-plant system, the N2O emissions from soybean seedling, maize seedling, sand, soil, sand-plant system and soil-plant system were measured by closed chamber method in greenhouse. At the same time the correlation of plant N2O emission with nitrate reductase activity, nitrate content and nitrite content of the plant leaves was also analyzed. The results clearly indicated that N2O could be a by-product of plant metabolism. The emissions of N2O from maize and soybean accounted for 93%-100% of the total N2O emissions in the sand-plant systems, and 79.18%-92% in the soil-plant systems. The flux of plant N2O emission was significantly correlated (R2 > or = 0.97, n = 6) with the nitrate reductase activities, nitrate content and nitrite content of the maize and soybean leaves.

Nitrate Reductase↗

PubMed2003

[New quantificational indexes in modern study of soil organic matter].

In modern study of soil organic matter, many new quantificational indexes and relevant testing methods, e.g., DOC, WSOC, HWC, ROC, MBC, MBN, PMC, PMN, Glu, Gla, Man, Mur, delta 13C, and CPMI, came forth with deepening study. Because they are disorderly and unsystematic, it is necessary to clarify these indexes. This paper summarized their origin, concept, and testing method, which is of significance in the modern study of soil organic matter.

Organic Chemicals↗

PubMed2003

[Cloning and expression of S9-1 gene of rice black-streaked dwarf virus in Escherichia coli].

The cDNA of RBSDV S9 was amplified by RT-PCR using the total RNA of infected maize leaves as the template, and then the PCR product was cloned into pBluescriptII SK. After the DNA sequence was determined, the S9-1 gene was subcloned into E. coli expression vector pET-21d. SDS-PAGE analysis revealed that a 40 kD protein was highly expressed. N-terminal sequence analysis confirmed the 40 kD protein was S9-1 protein. Antiserum was prepared using the purified protein. Western blotting indicated that S9-1 protein could be detected in the infected maize leaves.

Cloning, Molecular↗

PubMed2002

Deformation of angle profiles in forward kinematics for nullifying end-point offset while preserving movement properties.

This work describes a new approach that allows an angle-domain human movement model to generate, via forward kinematics, Cartesian-space human movement representation with otherwise inevitable end-point offset nullified but much of the kinematic authenticity retained. The approach incorporates a rectification procedure that determines the minimum postural angle change at the final frame to correct the end-point offset, and a deformation procedure that deforms the angle profile accordingly to preserve maximum original kinematic authenticity. Two alternative deformation schemes, named amplitude-proportional (AP) and time-proportional (TP) schemes, are proposed and formulated. As an illustration and empirical evaluation, the proposed approach, along with two deformation schemes, was applied to a set of target-directed right-hand reaching movements that had been previously measured and modeled. The evaluation showed that both deformation schemes nullified the final frame end-point offset and significantly reduced time-averaged position errors for the end-point as well as the most distal intermediate joint while causing essentially no change in the remaining joints. A comparison between the two schemes based on time-averaged joint and end-point position errors indicated that overall the TP scheme outperformed the AP scheme. In addition, no statistically significant difference in time-averaged angle error was identified between the raw prediction and either of the deformation schemes, nor between the two schemes themselves, suggesting minimal angle-domain distortion incurred by the deformation.

Algorithms↗

PubMed2002

Feasibility of generating adeno-associated virus packaging cell lines containing inducible adenovirus helper genes.

The adeno-associated virus (AAV) vector system is based on nonpathogenic and helper-virus-dependent parvoviruses. The vector system offers safe, efficient, and long-term in vivo gene transfer in numerous tissues. Clinical trials using AAV vectors have demonstrated vector safety as well as efficiency. The increasing interest in the use of AAV for clinical studies demands large quantities of vectors and hence a need for improvement in vector production. The commonly used transient-transfection method, although versatile and free of adenovirus (Ad), is not cost-effective for large-scale production. While the wild-type-Ad-dependent AAV producer cell lines seem to be cost-effective, this method faces the problem of wild-type Ad contamination. To overcome these shortcomings, we have explored the feasibility of creating inducible AAV packaging cell lines that require neither transfection nor helper virus infection. As a first step toward that goal, we have created a cell line containing highly inducible Ad E1A and E1B genes, which are essential for AAV production. Subsequently, the AAV Rep and Cap genes and an AAV vector containing a green fluorescent protein (GFP) reporter gene were stably introduced into the E1A-E1B cell line, generating inducible AAV-GFP packaging cell lines. Upon induction of E1A and E1B genes and infection with replication-defective Ad with E1A, E1B, and E3 deleted, the packaging cells yielded high-titer AAV-GFP vectors. Finally, the E2, E4, and VA genes of Ad, under the control of their endogenous promoters, were also introduced into these cells. A few producer cell lines were obtained, which could produce AAV-GFP vectors upon simple drug induction. Although future improvement is necessary to increase the stability and vector yield of the cells, our study has nonetheless demonstrated the feasibility of generating helper-virus-free inducible AAV producer cell lines.

Adenovirus E1A Proteins↗

PubMed2002

[Auricular reconstruction with Medpor framework and temporal-parietal fascia flap].

OBJECTIVE: In search of a simpler and safer technique for auricular reconstruction with good appearance. METHODS: Medpor implant was used as auricular framework, and covered by temporal fascia flap and skin graft. RESULTS: Ear reconstruction was successfully achieved in 19 cases, the newly formed ears all had good appearance after edema disappeared 1 or 2 months postoperatively. CONCLUSION: Medpor is a kind of good implant material because it is steady in nature, easy to be sculptured. Temporal fascia flap is rich in blood supply, tough and tensile in biomechanics. So the combination of Medpor implant framework with temporal fascia flap is preferable in auricular reconstruction.

Adolescent↗

PubMed2002

[Effects of applying nitrogen fertilizer at different stages in ploughed furrow on dry matter production and yield of rice].

The effects of applying nitrogen fertilizer in ploughed furrow at different stages on dry matter production and yield of rice were studied in a field experiment in 1999. The results showed that applying N fertilizer at booting stage (BS) had better effects on dry weight (2.9 g.hill-1) of leaf, stem and whole plant than at panicle primordia formation stage (PPFS), tillering stage (TS) and regular N fertilization (RF). Meanwhile, the dry weight of leaf and sheath as well as the leaf area index (LAI, 8.9) could be maintained at a high level for a relative long time in BS treatment, compared with PPFS, TS and RF treatments. Similar phenomenon was observed in the growth velocity (0.73 g.d-1.hill-1) of stem and whole plant, and the dry weight (10434 kg.hm-2) of seed. The grain yield of rice followed the sequence of BS > or = PPFS > TS > or = RF. Thus, the optimum stage of applying N fertilizer in ploughed furrow was the booting stage.

Agriculture↗