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Jing Zhuang

Publications and source records attributed to Jing Zhuang.

13 recordsLinked to original sources
PubMed2006

High efficiency and throughput system in directed evolution in vitro of reporter gene.

In vitro directed evolution, especially with DNA shuffling, is a powerful means in biological studies of protein structure and function, and consequently for industrial applications. Escherichia coli beta-glucuronidase (gusA) gene, a versatile and efficient reporter gene, was the model for studying in vitro directed evolution because of its stability, easy analysis of the enzyme properties and conveniently visible phenotype. We developed a high efficiency, throughput system for in vitro directed evolution using gusA reporter gene as the model. The system consisted mainly of three aspects: a prokaryotic expression vector pYPX251, an easy method for obtaining the mutated gene from DNA shuffling and a suitable selected strategy. The vector pYPX251 carried the moderately strong aacC1 gene promoter and T1T2 transcription terminator that allowed expression in E. coli. Over 10,000 individuals could be selected individually in a 9 cm Petri dish after colonies were absorbed on a nitrocellulose filter. A library, which contained 100,000 individuals was screened by incubating ten filter papers with X-Glu. The polymerase chain reaction products of the gusA gene, the fragments of 50-100 bp, with high mutation rates were purified using a dialysis bag from 10% PAGE after electrophoresis. The possibility of obtaining desirable mutations was increased dramatically as the size of the library expanded. A GUS variant, named GUS-TR, was obtained through this system, which is significantly more resistant to high temperature than the wild type enzyme. GUS-TR maintained its high activity even when the nitrocellulose filter containing the variant colony was heated at 100 degrees C for 30 min.

Biotechnology↗
PubMed2006

Hydrothermal synthesis of rare-earth fluoride nanocrystals.

In this paper, a hydrothermal synthetic route has been developed to prepare a class of rare-earth fluoride nanocrystals, which have shown gradual changes in growth modes with decreasing ionic radii and may serve as a model system for studying the underlying principle in the controlled growth of rare-earth nanocrystals. Furthermore, we demonstrate the functionalization of these nanocrystals by means of doping, which have shown visible-to-the-naked-eye green up-conversion emissions and may find application in biological labeling fields.

Fluorides↗
PubMed2006

Synthesis and characterization of sulfide and selenide colloidal semiconductor nanocrystals.

In this paper, we demonstrate the synthesis of sulfide and selenide nanocrystals in a water-ethanol mixed solution system. This synthetic way was based on the direct reactions between metal ions and S(2-)/Se. Linoleic acid was adopted to protect the nanocrystals from agglomeration. Without involving extreme experimental conditions, this less toxic synthetic route can be expected to bring more opportunities to nanocrystal-related research and application fields.

Journal Article↗
PubMed2006

Synthesis of CdSe, ZnSe, and ZnxCd1-xSe nanocrystals and their silica sheathed core/shell structures.

Uniform ZnxCd1-xSe nanocrystals have been prepared at the artificially designed water-oil interface using Na2SeO3, Cd(NO3)2, and Zn(NO3)2 as precursors. The chemical composition and band gap of the ZnxCd1-xSe nanocrystals can be adjusted via different combinations of source material. The coating of a SiO2 shell could transform the hydrophobic particles into hydrophilic particles. An advantage of this method is that a water phase could be added to the oleic acid (OLEA) synthesis system, which could be extended to make the synthesis of various nanocrystals more simple and flexible.

Journal Article↗
PubMed2006

Checkpoint kinase 2-mediated phosphorylation of BRCA1 regulates the fidelity of nonhomologous end-joining.

The tumor suppressor gene BRCA1 maintains genomic integrity by protecting cells from the deleterious effects of DNA double-strand breaks (DSBs). Through its interactions with the checkpoint kinase 2 (Chk2) kinase and Rad51, BRCA1 promotes homologous recombination, which is typically an error-free repair process. In addition, accumulating evidence implicates BRCA1 in the regulation of nonhomologous end-joining (NHEJ), which may involve precise religation of the DSB ends if they are compatible (i.e., error-free repair) or sequence alteration upon rejoining (i.e., error-prone or mutagenic repair). However, the precise role of BRCA1 in regulating these different subtypes of NHEJ is not clear. We provide here the genetic and biochemical evidence to show that BRCA1 promotes error-free rejoining of DSBs in human breast carcinoma cells while suppressing microhomology-mediated error-prone end-joining and restricting sequence deletion at the break junction during repair. The repair spectrum in BRCA1-deficient cells was characterized by an increase in the formation of >2 kb deletions and in the usage of long microhomologies distal to the break site, compared with wild-type (WT) cells. This error-prone repair phenotype could also be revealed by disruption of the Chk2 phosphorylation site of BRCA1, or by expression of a dominant-negative kinase-dead Chk2 mutant in cells with WT BRCA1. We suggest that the differential control of NHEJ subprocesses by BRCA1, in concert with Chk2, reduces the mutagenic potential of NHEJ, thereby contributing to the prevention of familial breast cancers.

BRCA1 Protein↗
PubMed2006

[Rational evolutionary design and modification of gene: a short-path of direct evolution].

Directed evolution is a powerful means in academic study and industrial application to modified and functionally improved proteins. There have been significant and impressive advances using the artificial method. Rational Evolutionary Design utilizes structural and sequence alignment information to create new genes and proteins. Rational Evolutionary Design has recently emerged as an attractive approach for studying function of proteins. The review mainly introduced four aspects: preferred codon usage, structural and sequence alignment, key domain analysis, site-directed recombination.

Directed Molecular Evolution↗
PubMed2005

Controlled hydrothermal synthesis and structural characterization of a nickel selenide series.

A series of nickel selenides (NiSe2 microcrystals, Ni(1-x)Se and Ni3Se2 microspheres) has been successfully synthesized through a convenient, low-temperature hydrothermal method. A good nucleation and growth environment has been created by forming a uniform and transparent solution reaction system. The compositions (including the x value of Ni(1-x)Se), phase structures, as well as the morphologies of nickel selenides, can be controlled by adjusting the Ni/Se ratio of the raw materials, the pH, the reaction temperatures and times, and so forth. The newly produced Se microspheres in the system have been used as both reactant and in situ template to the Ni(1-x)Se microspheres. It is found that Ni(1-x)Se microspheres act as the intermediate precursor during the formation of Ni3Se2 microspheres. Under certain conditions, hexagonal NiSe microspheres can be converted into rhombohedral NiSe nanowires in solution. The formation mechanisms of a series of nickel selenides has been investigated in detail by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. This work has provided a general, simple, and effective method to control the composition, phase structure, and morphology of metal selenides in aqueous solution, which will be important for inorganic synthesis methodology and further applications of selenides.

Journal Article↗
PubMed2005

A general strategy for nanocrystal synthesis.

New strategies for materials fabrication are of fundamental importance in the advancement of science and technology. Organometallic and other organic solution phase synthetic routes have enabled the synthesis of functional inorganic quantum dots or nanocrystals. These nanomaterials form the building blocks for new bottom-up approaches to materials assembly for a range of uses; such materials also receive attention because of their intrinsic size-dependent properties and resulting applications. Here we report a unified approach to the synthesis of a large variety of nanocrystals with different chemistries and properties and with low dispersity; these include noble metal, magnetic/dielectric, semiconducting, rare-earth fluorescent, biomedical, organic optoelectronic semiconducting and conducting polymer nanoparticles. This strategy is based on a general phase transfer and separation mechanism occurring at the interfaces of the liquid, solid and solution phases present during the synthesis. We believe our methodology provides a simple and convenient route to a variety of building blocks for assembling materials with novel structure and function in nanotechnology.

Journal Article↗
PubMed2004

[The experimental study of the relationship between preparation height and retention of complete crowns].

PURPOSE: This study was to discuss the influence of preparation height on retention of complete crown. METHODS: In this study we measured the retention of complete crown with the preparation height 2 mm, 3 mm, 4 mm and 5 mm. All crowns had no preparation taper and no bonding agent was used. The retention of crowns was measured and the data was statistically analyzed by t test. RESULTS: The preparation height was directly proportional to the retention of complete crown. And the crown with the height of 2 mm had enough retention when the crown had no preparation taper. CONCLUSION: In order to get enough retention of short height molar, we should induce the preparation taper.

Crowns↗
PubMed2003

Metastatic pattern of lymph node and surgery for gastric stump cancer.

BACKGROUND AND OBJECTIVES: Metastatic pattern of lymph node (LN) and surgery options for gastric stump cancer (GSC) remain controversial. The aim of this study was to investigate LN metastasis and lymphadenectomy for GSC for curative purposes. METHODS: Sixty-seven patients with GSC were analyzed retrospectively. RESULTS: The metastatic rates of LN were as follows: 63.3% in right cardia (No. 1), 33.3% in left cardia (No. 2), 75.0% in lesser curvature (No. 3), 53.3% in greater curvature (No. 4), 40.0% in celiac artery (No. 9), 60.0% in splenic hilus (No. 10), 72.7% in splenic artery (No. 11), 36.1% in hepatoduodenal ligament (No. 12), 8.3% in retropancreatic (No. 13), 21.4% in para-aortic (No. 16), 50% in supra-diaphragm (No. 111), 16.7% in LN within jejunal mesentery, respectively. All nine patients who only received simple laparotomy died within 1 year. The overall 5-year survival rate of GSC was 17.9% (12/67), including 100% for stage I, 80.0% for stage II, 12.1% for stage III, and 0% for stage IV. Moreover, the 5-year survival rate (36.7%, 11/30) for curative patients was significantly better than that (3.6%, 1/28) of non-curative patients (chi(2) = 7.76, P < 0.01). CONCLUSIONS: Our results imply that GSC has a wide range of LN metastases, including LN within jejunal mesentery in B-II reconstruction cases, and curable resection may obtain better results. Therefore, we suggest that radical operation for B-I patients needs removal of gastroduodenectomy anastomosis and the above LNs, and that B-II patients need removal of 10 cm of jejunum besides gastrojejunostomy anastomosis, and clearance of LN within its mesentery, in addition to B-I GSC.

Adenocarcinoma↗
PubMed2002

[Significance of COX-2, p53, proliferating cell nuclear antigen and nm23 expressions in gastric cancer and its behavior].

BACKGROUND & OBJECTIVE: Molecular biological studies indicated that abnormal expression of cyclooxygenase-2(COX-2), p53, proliferating cell nuclear antigen(PCNA), and nm23 correlate with the development of gastric cancer, but the relationship between abnormal expression of above gene proteins and the biological behavior of gastric cancer was not yet clear. This study was designed to investigate the relationship between expressions of COX-2, p53, PCNA, and nm23 and the clinicopathological behavior in gastric cancer. METHODS: The expressions of COX-2, p53, PCNA, and nm23 were detected by using immunohistochemical(SP) method. RESULTS: (1) The overexpression rate of COX-2 in gastric cancer was 70.4% (50/71), and the overexpression of COX-2 was correlated to tumor size, gross morphology, histological type, lymph node metastases, and clinicopathological stage of gastric cancer (P < 0.05, or P < 0.01). (2) The overexpression rates of p53 and PCNA in 71 surgically removed specimens from the patients with gastric cancer were 74.6% and 78.9%, respectively. And the expressions of p53 (86.7%) and PCNA (88.8%) in gastric cancer patients with lymph node metastasis were significantly higher than those in patients without lymph node metastasis (53.8% and 61.5%) (both, P < 0.05), respectively. Moreover, expressions of p53(52.2%) and PCNA(60.9%) in stage I + II patients were lower than those(85.4% and 87.5%) in stage III + IV (both, P < 0.05). (3) The low-expression of nm23 in gastric cancer was 71.8%, and its low-expression rate of nm23 in patients without lymph node metastasis(88.5%) and in stage I + II (91.3%) were much higher than those in the patients with lymph node metastasis (62.2%) and in stage III + IV (62.5%) (respectively, P < 0.05). (4) The differences of histological types, depth of invasion, lymph node metastasis and clinical stage were significantly different(P < 0.05 or P < 0.001), between the patients with two or more genes expression of COX-2, p53, PCNA, and nm23 and those with less one gene expression. CONCLUSION: Our results suggest that abnormal expressions of COX-2, p53, PCNA, and nm23 associate with malignant potential, lymph node metastasis and clinical stage, and they might therefore play a role in development of gastric cancer.

Cyclooxygenase 2↗
PubMed2002

[Significance of urinary nuclear matrix protein 22 in diagnosis of transitional cell carcinoma of urinary tract].

BACKGROUND & OBJECTIVE: There is no effective non-invasive monitoring method for transitional cell carcinoma of urinary tract(TCCU). It was recently reported that nuclear matrix protein 22(NMP22) could be used to diagnose TCCU. This study was designed to evaluate the significance of NMP22 in TCCU as a new urinary tumor marker and its influence factors. METHODS: The authors detected 87 patients with urinary system disease(including 29 cases with TCCU) with ELISA-NMP agent box. The patients with urinary infection were excluded. RESULTS: The positive value was set at more than 10 u/ml. The sensitivity and specificity of NMP22 on TCCU were 86.2% and 94.3%, respectively (benign diseases of urinary system used as control), with significant advantages over voided-urine cytology (86.2% vs 42.3%, P < 0.001). The main factors that caused false-positive results were urinary infection, the other malignant tumors of urinary system, bowel interposition, and nephrolith. CONCLUSION: Urinary NMP22 is a good tumor marker and could be used an alternation of voided-urine cytology for monitoring and diagnosis of TCCU.

Adult↗