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Ning Xu

Publications and source records attributed to Ning Xu.

64 records · Page 4Linked to original sources
PubMed2002

Nucleotide sequence of the p53 cDNA of beluga whale (Delphinapterus leucas).

The cDNA (DNA complementary to RNA) of the p53 gene of the beluga whale (Delphinapterus leucas) was sequenced by the method of 5'- and 3'-rapid amplification of cDNA ends (RACE) with the cDNA made for the RNA obtained from fresh peripheral blood leukocytes isolated from two animals. Primers for the RACE method were synthesized based on the sequence of the DNA of beluga whale corresponding to exon 5 of the human p53 gene, which was determined after amplification of the DNA isolated from the liver from a beluga whale by using a pair of primers for the human sequence. The sequenced cDNA had a 2150-nucleotide length and contained the whole region corresponding to human exons 1 through 11. The reading frame was 1164 bp (base pair) long and began in exon 2 and ended in exon 11, coding for a 387-amino acid protein. The nucleotide sequence of the reading frame showed high similarity over 85% with pig, sheep, cow, and human genes. The similarities with the former two animals at the amino acid level were also more than 85%. Lower similarity of the beluga whale p53 gene was also found with those of lower tetrapods, fish and invertebrates.

Amino Acid Sequence↗
PubMed2002

Effects of platelet-activating factor, tumor necrosis factor, and interleukin-1alpha on the expression of apolipoprotein M in HepG2 cells.

Apolipoprotein M (apoM) is a recently discovered human apolipoprotein predominantly present in high-density lipoprotein (HDL) in plasma, exclusively expressed in liver and in kidney. The function of apoM is yet unknown. The human apoM gene is located in the major histocompatibility complex class III region on chromosome 6. Because many genes located in this region are related to the immune response, we have investigated whether apoM might also be involved in the host inflammatory response. In this study we examined effects of the platelet-activating factor (PAF), tumor necrosis factor (TNF-alpha), and interleukin-1alpha (IL-1alpha) on apoM expression in a hepatoblastoma cell line, HepG2 cells. PAF significantly enhanced the apoM mRNA levels and the secretion of apoM in HepG2 cell cultures. The enhancement of apoM secretion is seen at a low concentration of PAF (2 ng/ml), whereas a high concentration of PAF increases both the apoM mRNA levels and apoM secretion. Neither TNF-alpha nor IL-1alpha influenced apoM mRNA level and secretion. Furthermore, Lexipafant, a PAF-receptor (PAF-R) antagonist significantly suppressed the mRNA level and the secretion of apoM in HepG2 cells in a dose-dependent manner. Neither PAF nor Lexipafant influenced the mRNA levels and the secretion of apoA-I, apoB and apoE in HepG2 cells, indicating that the effects of PAF or Lexipafant on the apoM production on hepatic cells are selective for apoM. The cellular mechanism of the effects of PAF or Lexipafant on apoM metabolism requires further investigations.

Apolipoprotein A-I↗
PubMed2002

The effects of the catalytic converter and fuel sulfur level on motor vehicle particulate matter emissions: gasoline vehicles.

Scanning mobility and electrical low-pressure impactor particle size measurements conducted during chassis dynamometer testing reveal that neither the catalytic converter nor the fuel sulfur content has a significant effect on gasoline vehicle tailpipe particulate matter (PM) emissions. For current technology, port fuel injection, gasoline engines, particle number emissions are < or = 2 times higher from vehicles equipped with blank monoliths as compared to active catalysts, insignificant in contrast to the 90+% removal of hydrocarbons. PM mass emission rates derived from the size distributions are equal within the experimental uncertainty of 50-100%. Gravimetric measurements exhibit a 3-10-fold PM mass increase when the active catalyst is omitted, which is attributed to gaseous hydrocarbons adsorbing onto the filter medium. Both particle number and gravimetric measurements show that gasoline vehicle tailpipe PM emissions are independent (within 2 mg/mi) of fuel sulfur content over the 30-990 ppm concentration range. Nuclei mode sulfate aerosol is not observed in either test cell measurements or during wind tunnel testing. For three-way catalyst equipped vehicles, the principal sulfur emission is SO2; however a sulfur balance is not obtained over the drive cycle. Instead, sulfur is stored on the catalyst during moderate driving and then partially removed during high speed/load operation.

Air Pollutants↗
PubMed2002

The effects of the catalytic converter and fuel sulfur level on motor vehicle particulate matter emissions: light duty diesel vehicles.

Wind tunnel measurements and direct tailpipe particulate matter (PM) sampling are utilized to examine how the combination of oxidation catalyst and fuel sulfur content affects the nature and quantity of PM emissions from the exhaust of a light duty diesel truck. When low sulfur fuel (4 ppm) is used, or when high sulfur (350 ppm)fuel is employed without an active catalyst present, a single log-normal distribution of exhaust particles is observed with a number mean diameter in the range of 70-83 nm. In the absence of the oxidation catalyst, the high sulfur level has at most a modest effect on particle emissions (<50%) and a minor effect on particle size (<5%). In combination with the active oxidation catalyst tested, high sulfur fuel can lead to a second, nanoparticle, mode, which appears at approximately 20 nm during high speed operation (70 mph), but is not present at low speed (40 mph). A thermodenuder significantly reduces the nanoparticle mode when set to temperatures above approximately 200 degrees C, suggesting that these particles are semivolatile in nature. Because they are observed only when the catalyst is present and the sulfur level is high, this mode likely originates from the nucleation of sulfates formed over the catalyst, although the composition may also include hydrocarbons.

Air Pollutants↗
PubMed2002

Mining protein sequences for motifs.

We use methods from Data Mining and Knowledge Discovery to design an algorithm for detecting motifs in protein sequences. The algorithm assumes that a motif is constituted by the presence of a "good" combination of residues in appropriate locations of the motif. The algorithm attempts to compile such good combinations into a "pattern dictionary" by processing an aligned training set of protein sequences. The dictionary is subsequently used to detect motifs in new protein sequences. Statistical significance of the detection results are ensured by statistically determining the various parameters of the algorithm. Based on this approach, we have implemented a program called GYM. The Helix-Turn-Helix motif was used as a model system on which to test our program. The program was also extended to detect Homeodomain motifs. The detection results for the two motifs compare favorably with existing programs. In addition, the GYM program provides a lot of useful information about a given protein sequence.

Algorithms↗
PubMed2002

Time-dependent reversal of sepsis-induced PMN uptake and lung vascular injury by expression of CD18 antagonist.

We determined the time-dependent effects of conditional expression of neutrophil inhibitory factor (NIF), a specific 41-kDa CD18 integrin antagonist, on the time course of NIF expression and lung PMN (polymorphonuclear leukocyte) infiltration and vascular injury in a model of Escherichia coli-induced sepsis in mice. Studies were made in mice transduced with the E-selectin (ES) promoter-NIF construct (using liposomes) in which the NIF cDNA was driven by the inflammation- and endothelial cell-specific ES promoter. We observed time-dependent expression of NIF in pulmonary vascular endothelium that paralleled the ES expression. Expression of both was evident at 1 h after E. coli challenge, peaked at 3-6 h, and returned to basal level within 48 h. We observed that increases in PMN uptake and transalveolar PMN migration induced by E. coli challenge were reversed in a time-dependent manner following NIF expression in mice. NIF expression also prevented the progression of lung vascular injury and edema formation following E. coli challenge. Thus the conditional expression of NIF using the ES promoter can reverse, in a time-dependent manner, lung PMN infiltration and vascular injury induced by gram-negative sepsis. The results support the model that initial engagement of CD18 integrins enables the further recruitment of additional PMN into lung tissues such that PMN continue to sequester and migrate after E. coli challenge.

Amino Acid Sequence↗
PubMed2002

[Dexamethasone enhances the effect of tropisetron and ondansetron against nausea and vomiting against nausea and vomiting after patient-controlled analgesia].

OBJECTIVE: To study the enhancement by dexamethasone of the effect of ondansetron and tropiesetron against postoperative nausea and vomiting (PONV) in patients receiving patient-controlled analgesia (PCA) and observe the effect of dexamethasone on wound healing. METHODS: One hundred and twenty elective surgical patients receiving PCA were divided into 4 groups, including 2 control groups with the prescription of ondansetron (8 mg) and tropiesetron (3 mg) respectively (control A and B) and 2 observation groups in which the patients were given ondansetron (8 mg) plus dexamethasone (10 mg) and tropiesetron (3 mg) plus dexamethasone (10 mg) respectively (observation groups C and D). The incidence and severity of PONV was observed at 4, 8, 2, 24 h and 2, 3 d postoperatively, and the time and grade of healing of the wound evaluated. RESULTS: Significant difference in PONV between group A and group B was observed (P<0.01), and in the observation groups, PONV was markedly reduced compared with the control groups (C vs A, P<0.01; D vs B, P<0.05). In light of the time and grade of wound healing, the observation groups differed little from the control groups. CONCLUSION: Dexamethasone (10 mg) can greatly enhance the effect of ondansetron and tropiesetron against PONV in patients receiving PCA without interfering the healing of the wound.

Analgesia, Patient-Controlled↗
PubMedDate not supplied

A method for the solvent extraction of low-boiling-point plant volatiles.

A new method has been developed for the extraction of volatiles from plant materials and tested on seedling tissue and mature leaves of Arabidopsis thaliana, pine needles and commercial mixtures of plant volatiles. Volatiles were extracted with n-pentane and then subjected to quick distillation at a moderate temperature. Under these conditions, compounds such as pigments, waxes and non-volatile compounds remained undistilled, while short-chain volatile compounds were distilled into a receiving flask using a high-efficiency condenser. Removal of the n-pentane and concentration of the volatiles in the receiving flask was carried out using a Vigreux column condenser prior to GC-MS. The method is ideal for the rapid extraction of low-boiling-point volatiles from small amounts of plant material, such as is required when conducting metabolic profiling or defining biological properties of volatile components from large numbers of mutant lines.

Alcohols↗
PubMedDate not supplied

Treatment of advanced gastric cancer by chemotherapy combined with autologous cytokine-induced killer cells.

The effects of autologous cytokine-induced killer (CIK) (CD3+CD56+) cells together with chemotherapy were investigated in patients who suffered from advanced gastric cancers (stage IV). Fifty-seven patients were divided into two groups: chemotherapy plus CIK biotherapy and chemotherapy alone. CIK cells were induced from autologous peripheral blood mononuclear cells in vitro and separated by flow cytometry and then transfused into the patients. The T-lymphocyte subgroups (CD3+, CD4+ or CD8+), CIK cells and NK cells (CD3-CD56+) were separated and determined by flow cytometry and the serum levels of MG7-Ag, CA72-4, CA19-9 and CEA were determined by ELISA or ECLIA. It was demonstrated that the cytotoxic activity of CIK cells reached a maximum between days 14 to 21 (68.7+/-10.9% and 65.3+/-10.4%, respectively). The amounts of CIK cells were gradually increased from day 0 to day 21 and slightly decreased in the further incubations. Thereafter, the CIK cells on days 14 to 21 (with the highest population of CIK cells) transfused back to the patients. The serum levels of the tumor markers were significantly decreased, the host immune function was increased and the short-term curative effect as well as the quality of life (QOL) were improved in the patients treated by chemotherapy plus CIK cells compared to the patients treated by chemotherapy alone. Moreover, the 2-year life-span was prolonged in the group treated by chemotherapy plus CIK cells compared to the group treated with chemotherapy alone. It is concluded that chemotherapy plus CIK cells has obvious benefits for patients who suffer from advanced gastric cancers.

Adult↗