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Li Xu

Publications and source records attributed to Li Xu.

At least 73 records · Page 4Linked to original sources
PubMed2005

Two abundant bioaccumulated halogenated compounds are natural products.

Methoxylated polybrominated diphenyl ethers (MeO-PBDEs) have been found bioaccumulated in the tissues of a variety of aquatic animals and at concentrations comparable to those of anthropogenic halogenated organic compounds, including polychlorinated biphenyls (PCBs). The origin of the MeO-PBDEs has been uncertain; circumstantial evidence supports a natural and/or an industrial source. By analyzing the natural abundance radiocarbon content of two MeO-PBDEs isolated from a True's beaked whale (Mesoplodon mirus), we show that these compounds were naturally produced.

Adipose Tissue↗
PubMed2005

The formation of cucurbit[n]uril (n = 6, 7) complexes with amino compounds in aqueous formic acid studied by capillary electrophoresis.

For analytes involved in dynamic equilibrium processes, capillary electrophoresis is a powerful method of determining binding constants. In this work, the complex formation between cucurbit[n]uril (CB[n] n = 6, 7) and some amino compounds was studied by capillary electrophoresis in aqueous formic acid (65% v/v). Four groups of positional and structural isomers (o, m, p-methylanilines; m, p-nitroanilines; benzidine and o-tolidine; alpha, beta-naphthylamines and 1,5-diaminonaphthalene) were selected as model compounds for study of their host-guest inclusion complexation. The interactions between CB[n] (n = 6, 7) and the model compounds were also investigated using a molecular modeling method. The results indicate that the interactions of the compounds with CB[n] (n = 6, 7) are strongly affected by the position of the substituent(s) on the aromatic ring and the ion-dipole interaction between guest molecule and CB. Furthermore, the type and the concentration of CBs on the separation and migration behavior of the amino compounds were also studied.

Amines↗
PubMed2005

The mouse chorionic gonadotropin beta-subunit-like (muCG beta l) molecule produced by tumor cells elicits the switch of T-cell immunity response from TH2 to TH1 in mice immunized with DNA vaccine based on rhesus monkey homologous CG beta (rmCG beta).

BACKGROUND: CG beta is expressed not only in placenta, but also in a wide range of tumors. To study DNA vaccine based on xenogeneic CG beta for cancer immuno-therapy, we investigated whether rhesus monkey CG beta (rmCG beta) DNA vaccine could induce protective T-cell responses and humoral responses in mouse. METHODS: We constructed a plasmid containing the rmCG beta coding sequence. Two cloned syngeneic SP2/0 myeloma cell lines that stably express muCG beta l (SP2/0-muCG beta l) and HN (SP2/0-HN) protein were established. Inoculation of these cell lines was made into mice that had been immunized with DNA vaccine. Specific IgG and IgG type were measured by ELISA and the cytokine expression was detected with RT-PCR. To measure the lymphocyte metabolic activity, the MTS assay was used. RESULTS: After injection of SP2/0-muCG beta l into mice that had been immunized with DNA vaccine, a significant increase in the IgG2a specific to the antigen (p < 0.05) and a decrease in the specific IgG1 (p < 0.05) were measured. The expression of T(H)1 but not T(H)2 cytokines, including IFN-gamma and IL-2, were detected in the splenocytes. However, injection of tumor cells expressing irrelevant or mock molecules into immunized mice could not induce these changes. The survival rate of vaccine-immunized mice injected with SP2/0-muCG beta l was as high as 58.3% after 55 days. CONCLUSIONS: The rmCG beta DNA vaccine has proved to be a potential strategy for protection against tumors with homologous molecules. The muCG beta l produced by tumors is able to elicit an immunity switch from T(H)2 to T(H)1 in vaccinated mice.

Animals↗
PubMed2005

Effect of cigarette smoke extract on the proliferation of human airway epithelial cells and expression and activation of FAK.

The effect of cigarette smoke extract (CSE) on the proliferation of human airway epithelial cells and the possible mechanism was studied. After airway epithelial cells were treated with different concentrations of CSE for 24 h, the cell proliferation was measured by MTT and the distribution of different cell cycles by flow cytometry. The FAK expression level was detected by Western blot and the degree of tyrosine phosphorylation by immunoprecipitation. The results showed that CSE could inhibit the proliferation of human airway epithelial cells, arrest the epithelial cells in G1 phase of cell cycle, dramatically decrease the number of epithelial cells in S and G2 phases; Meanwhile CSE could decrease the expression level of FAK and the degree of its tyrosine phosphorylation. The above effects of CSE were concentration-dependent. The expression of FAK and the degree of its phosphorylation was positively correlated to the increased number of epithelial cells in G1 phase, and negatively to the number of epithelial cells in S and G2 phases. It was concluded that the mechanism by which CSE could inhibit the proliferation of human epithelial cells was contributed to the increased expression and activation of FAK.

Bronchi↗
PubMed2005

Surgical resection of limited disease small cell lung cancer in the new era of platinum chemotherapy: Its time has come.

OBJECTIVE: Although resection is not the standard of care in treating small cell lung cancer, new platinum drugs and modern staging have allowed the role of surgery to be reevaluated. METHODS: We reviewed our institutional experience of 1415 patients with small cell lung cancer from 1976 to 2002 among whom 82 (6%) underwent surgery with curative intent. RESULTS: Median age at surgery was 62 years, and small cell lung cancer of mixed morphology represented 14 of 82 (17%). Treatment consisted of surgery alone in 11% of cases (9/82), surgery with neoadjuvant therapy in 22% (18/82), and surgery with adjuvant therapy in 55% (45/82). Prophylactic cranial irradiation was given to 23% (19/82). The 5-year survival of the entire cohort was 42%. The 5-year survival of patients receiving adjuvant chemotherapy (n = 41) was significantly different according to whether patients had received platinum or nonplatinum regimens (68% vs 32.2%, P = .04). Among patients with stage I disease who received adjuvant chemotherapy (n = 24), the 5-year survivals for patients receiving platinum and nonplatinum chemotherapy were 86% and 42%, respectively ( P < .02). If patients who received either neoadjuvant or adjuvant therapy (n = 56) were considered, the 5-year survival was significantly better for platinum than for nonplatinum chemotherapy (62% vs 36%, P = .05). The 5-year survival was also better for those undergoing lobectomies (n = 52) than for those with limited resections (n = 15, 50% vs 20%, P = .03). Survival outcomes also differed by gender, with female patients having a 5-year survival advantage over male patients (60% vs 28%, P = .004). CONCLUSION: These results support a reevaluation of the role of surgery in the multimodality therapy for small cell lung cancer, which currently includes only radiotherapy and chemotherapy.

Adult↗
PubMed2005

Persistent organochlorine pollutants in surface sediments and economic shellfish of Minjiang Estuary-Mazu and Xiamen-Jinmen sea areas.

Samples of surface sediment and shellfish were collected from Minjiang Estuary-Mazu and Xiamen-Jinmen sea areas and were analyzed for hexachlorocyclohexanes (HCHs), dichlorodiphenyl-trichlorophenyl (DDT) and its degraded derivatives dichloro-diphenyl-dichloroethane (DDT) and dichloro-dichlorophenyl-ethylene (DDE), and polychlorinated biphenyls (PCBs) by gas chromatography. Concentration ranges of HCHs, DDTs, and PCBs in the sediments were 0.03-0.48, 1.10-14.3, and ND to 0.76 ng/g dw, respectively; those for shellfish samples were ND to 1.5, 21.5-892, dw and ND-3.7 ng/g dw, respectively. The results showed that the concentrations of such oganochlorine compounds (OCs) in the sediments were usually low as compared with other sea areas and estuaries, and the organochlorines were accumulated in marine bivalve mollusks, particularly in oyster. With respect to the concentrations of HCHs, DDTs, and PCBs in the samples of either sediment or shellfish, DDTs were higher than HCHs and PCBs. The concentrations of OCs in shellfish samples varied with the sampling locations and organism species but were generally higher than those in the sediments. The concentration distributions, compositions, and residue levels of these OCs are extensively discussed and evaluated.

Animals↗
PubMed2005

Rapid and simple detection of blaCTX-M genes by multiplex PCR assay.

A novel multiplex PCR assay is described (CTX-Mplex PCR) that allows rapid detection of bla(CTX-M) genes and discrimination between groups 1, 2, 9 and 25/26. The specificity and sensitivity of the assay were evaluated with 10 control strains and then applied to 62 clinical isolates. The multiplex PCR detected and classified bla(CTX-M) genes with 100 % accuracy. The utilization of a denaturing HPLC WAVE system to size the PCR products automatically from the multiplex PCR enhances the assay by saving time and costs.

Bacterial Proteins↗
PubMed2005

Fyn kinase-mediated phosphorylation of NMDA receptor NR2B subunit at Tyr1472 is essential for maintenance of neuropathic pain.

Despite abundant evidence implicating the importance of N-methyl-D-aspartate (NMDA) receptors in the spinal cord for pain transmission, the signal transduction coupled to NMDA receptor activation is largely unknown for the neuropathic pain state that lasts over periods of weeks. To address this, we prepared mice with neuropathic pain by transection of spinal nerve L5. Wild-type, NR2A-deficient, and NR2D-deficient mice developed neuropathic pain; in addition, phosphorylation of NR2B subunits of NMDA receptors at Tyr1472 was observed in the superficial dorsal horn of the spinal cord 1 week after nerve injury. Neuropathic pain and NR2B phosphorylation at Tyr1472 were attenuated by the NR2B-selective antagonist CP-101,606 and disappeared in mice lacking Fyn kinase, a Src-family tyrosine kinase. Concomitant with the NR2B phosphorylation, an increase in neuronal nitric oxide synthase activity was visualized in the superficial dorsal horn of neuropathic pain mice by NADPH diaphorase histochemistry. Electron microscopy showed that the phosphorylated NR2B was localized at the postsynaptic density in the spinal cord of mice with neuropathic pain. Indomethacin, an inhibitor of prostaglandin (PG) synthesis, and PGE receptor subtype EP1-selective antagonist reduced the NR2B phosphorylation in these mice. Conversely, EP1-selective agonist stimulated Fyn kinase-dependent nitric oxide formation in the spinal cord. The present study demonstrates that Tyr1472 phosphorylation of NR2B subunits by Fyn kinase may have dual roles in the retention of NMDA receptors in the postsynaptic density and in activation of nitric oxide synthase, and suggests that PGE2 is involved in the maintenance of neuropathic pain via the EP1 subtype.

Animals↗
PubMed2005

Relative contributions of spectral and temporal cues for phoneme recognition.

Cochlear implants provide users with limited spectral and temporal information. In this study, the amount of spectral and temporal information was systematically varied through simulations of cochlear implant processors using a noise-excited vocoder. Spectral information was controlled by varying the number of channels between 1 and 16, and temporal information was controlled by varying the lowpass cutoff frequencies of the envelope extractors from 1 to 512 Hz. Consonants and vowels processed using those conditions were presented to seven normal-hearing native-English-speaking listeners for identification. The results demonstrated that both spectral and temporal cues were important for consonant and vowel recognition with the spectral cues having a greater effect than the temporal cues for the ranges of numbers of channels and lowpass cutoff frequencies tested. The lowpass cutoff for asymptotic performance in consonant and vowel recognition was 16 and 4 Hz, respectively. The number of channels at which performance plateaued for consonants and vowels was 8 and 12, respectively. Within the above-mentioned ranges of lowpass cutoff frequency and number of channels, the temporal and spectral cues showed a tradeoff for phoneme recognition. Information transfer analyses showed different relative contributions of spectral and temporal cues in the perception of various phonetic/acoustic features.

Adult↗
PubMed2005

The pattern electroretinogram in glaucoma patients with confirmed visual field deficits.

PURPOSE: To better understand the relationship between the amplitude of the pattern electroretinogram (PERG) and visual loss, measured with static automated perimetry. METHODS: Transient PERGs were recorded in 15 patients (31-77 years) and 16 normal individuals (26-65 years). An eye was considered to have glaucomatous damage only if there was an abnormal disc, an abnormal 24-2 Humphrey visual field result (pattern stand deviation, glaucoma hemifield test, and cluster) and an abnormal multifocal visual evoked potential. All the worse (more affected) eyes of the patients and six of the better eyes met these criteria. The N95 amplitude of the PERG was measured from the positive peak (P50) at approximately 50 ms to the trough at approximately 95 ms. The ratio of N95 to P50-the N95 amplitude divided by the P50 amplitude-was also measured. RESULTS: First, the PERG was within normal limits for 4 (26.7%) of the worse eyes. Overall, 6 (28.6%) of the 21 eyes that met the criteria for glaucomatous damage had normal PERGs on both PERG measures. Because the normal individuals were younger than the patients, an even larger number of normal PERGs might be expected with an age-appropriate control group. Second, the N95 amplitude was nonlinearly related to visual field sensitivity when sensitivity was plotted on a linear plot. Small field losses were associated with disproportionately large losses in PERG amplitude. Third, the PERG from both eyes of a patient were very similar, even when the visual fields suggested very different levels of damage. CONCLUSIONS: These results are consistent with the view that very early damage can affect the PERG, even before the visual field shows a loss. At the same time, it is clear that patients with clear glaucomatous damage can have normal-appearing PERGs. An explanation is proposed to account for these findings.

Adult↗
PubMed2005

Efficacy of a cochlear implant simultaneous analog stimulation strategy coupled with a monopolar electrode configuration.

OBJECTIVES: The present study was performed to evaluate the efficacy and clinical feasibility of using monopolar stimulation with the Clarion Simultaneous Analog Stimulation (SAS) strategy in patients with cochlear implants. METHODS: Speech recognition by 10 Clarion cochlear implant users was evaluated by means of 4 different speech processing strategy/electrode configuration combinations; ie, SAS and Continuous Interleaved Sampling (CIS) strategies were each used with monopolar (MP) and bipolar (BP) electrode configurations. The test measures included consonants, vowels, consonant-nucleus-consonant words, and Hearing in Noise Test sentences with a +10 dB signal-to-noise ratio. Additionally, subjective judgments of sound quality were obtained for each strategy/configuration combination. RESULTS: All subjects but 1 demonstrated open-set speech recognition with the SAS/MP combination. The group mean Hearing in Noise Test sentence score for the SAS/MP combination was 31.6% (range, 0% to 92%) correct, as compared to 25.0%, 46.7%, and 37.8% correct for the CIS/BP, CIS/MP, and SAS/BP combinations, respectively. Intersubject variability was high, and there were no significant differences in mean speech recognition scores or mean preference ratings among the 4 strategy/configuration combinations tested. Individually, the best speech recognition performance was with the subject's everyday strategy/configuration combination in 72% of the applicable cases. If the everyday strategy was excluded from the analysis, the subjects performed best with the SAS/MP combination in 37.5% of the remaining cases. CONCLUSIONS: The SAS processing strategy with an MP electrode configuration gave reasonable speech recognition in most subjects, even though subjects had minimal previous experience with this strategy/configuration combination. The SAS/MP combination might be particularly appropriate for patients for whom a full dynamic range of electrical hearing could not be achieved with a BP configuration.

Adult↗
PubMed2005

[Clinicopathologic features and treatment outcomes of primary hepatic lymphoma: a report of four cases].

BACKGROUND & OBJECTIVE: Primary hepatic lymphoma (PHL), a rare malignancy, has seldom been reported. This article was to investigate clinicopathologic features and treatment of PHL. METHODS: Data of 4 patients with PHL, treated in Cancer Center, Sun Yat-sen University from Nov. 1994 to May 2004, were retrospectively analyzed. RESULTS: Of the 4 patients, 3 were men, and 1 was woman, with a median age of 53 years old; 3 had single focus, and 1 had multi-foci. All patents were positive for HBV antigen, 3 were misdiagnosed preoperatively, and 1 had no clear diagnosis before operation. Pathologic examination revealed that 3 were B-cell non-Hodgkin's lymphoma, and 1 was Hodgkin's lymphoma. Two patients received resection, and 2 received biopsy; all patients received adjuvant chemotherapy postoperatively. CONCLUSIONS: HBV infection might relate with the development of PHL. PHL should be considered for the patients presented liver mass and B-symptomatolgy. Resection followed by adjuvant chemotherapy with CHOP regiment seems to be the best option for PHL.

Adult↗
PubMed2005

[The relationship between intrathyroidal dendritic cells and humoral immune disorder in Graves' disease].

OBJECTIVE: To investigate the relationship between intrathyroidal dendritic cells and humoral immune disorder in Graves' disease. METHODS: With the use of S-100 protein antibodies and the help of SP immunohistochemical method, the number and distribution of S-100 protein positive dendritic cells were observed in thyroid glands from 34 patients with Graves' disease and 5 controls. Serum thyroid stimulating antibodies (TSAb) before operation were measured with human embryo-kidney cells expressing the recombinant thyrotrophin receptor. The correlation between the infiltrating degree of intrathyroidal dendritic cells and the values of serum TSAb was analyzed in patients with Graves' disease. RESULTS: In normal thyroid glands, no S-100 protein positive dendritic cells were found. Dendritic cells were seen in all observed thyroid glands from patients with Graves' disease. Most of the dendritic cells were seen in close contact with the adjacent thyroid epithelial cells or infiltrating lymphocytes. The infiltrating degree of intrathyroidal dendritic cells in Graves' disease correlated closely with the values of serum TSAb (r = 0.4461, P < 0.01). CONCLUSION: It is suggested that the intrathyroidal dendritic cells have a close relation with humoral immune disorder and play an important role in the initiation and/or maintenance of thyroid autoimmune reaction in Graves' disease.

Adult↗
PubMed2005

[Screening and identification of a strain for hydroxylation of nicotinic acid].

Strain screening was conducted on a large scale in order to develop a biotransforming process for 6-hydroxynicotinic acid production. A strain named as NA-1 was isolated from soil which could transform nicotinic acid into a new product showed by HPLC. The new product was identified as 6-hydroxynicotinic acid by MS and 1H-NMR. The morphology, physiological and biochemical characteristics of strain NA-1 were studied and showed that characteristics of strain NA-1 were essentially consistent with Pseudomonas putida. The analysis of 16S rDNA sequence from strain NA-1 suggested that strain NA-1 was clustered together with P. putida in phylogenetic tree and the sequence identity between stain NA-1 and Pseudomonas putida was 99%. So strain NA-1 was identified to P. putida.

Chromatography, High Pressure Liquid↗
PubMed2005

[Multivariate prognostic analysis in gastric carcinoma patients after radical operation].

BACKGROUND & OBJECTIVE: Whether received radical operation is an important prognostic factor of gastric carcinoma. But the long-term efficacies of radical operation on different patients are not the same. This study was to investigate prognostic factors of gastric carcinoma. METHODS: Clinical data of 405 patients with gastric carcinoma, received radical operation from Jan. 1985 to Dec. 1995 in Cancer Center of Sun Yat-sen University, were analyzed retrospectively. Life table method was used to analyze survival rate, Wilcoxon test was used for statistical comparison, and Cox regression model was used for multivariate analysis. RESULTS: The 5-year overall survival rate was 43.4%. The 5-year survival rates of patients in pathologic TNM (pTNM) stage I, II, III, and IV were 75.6%, 58.7%, 28.0%, and 18.4%, respectively (P < 0.01). The 5- year survival rates of patients with tumor sizes of less than 2.0 cm, 2.0-3.9 cm, 4.0-5.9 cm, 6.0-7.9 cm, and no less than 8.0 cm were 82.0%, 57.4%, 43.7%, 38.7%, and 26.9%, respectively (P < 0.05). In addition, the 5-year survival rate was higher in patients with perioperative chemotherapy than in patients without perioperative chemotherapy (47.2% vs. 37.8%, P < 0.05). Univariate analysis showed that perioperative chemotherapy, Borrmann type, tumor size, pathologic type, and pTNM stage were prognostic factors of gastric carcinoma. Multivariate analysis showed that pTNM stage, tumor size, and perioperative chemotherapy were independent prognostic factors of gastric carcinoma. CONCLUSIONS: pTNM stage, tumor size, and perioperative chemotherapy are the most significant factors influencing prognosis of gastric carcinoma patients after radical operation. Perioperative chemotherapy contributes to enhance survival rate of gastric carcinoma patients.

Adenocarcinoma↗
PubMed2005

[Perform analyse on the predictive model of ischemic cardiovascular diseases in Qingdao].

OBJECTIVE: To explore the clinical usage of the methods and tools of the 10-year's risk estimation of ischemic cardiovascular disease (ICVD) in Chinese. METHODS: The risk of ICVD in 2287 middle-aged Qingdao people was evaluated by the methods and tools of the 10-year's risk estimation of ICVD in Chinese, which was developed by Cardiovascular Institute, Chinese Academy of Medical Sciences. RESULTS: (1) 98.16% of male and 99.39% of female had a 10-year absolute risk of ICVD less than 10%. 0.19% of male and 0.15% of female had a 10-year absolute risk of ICVD higher than 20%. (2) In the low risk group (absolute risk < 10%) detection rate of abnormal SBP, FBG, TC, BMI was 100%, 20.8%, 75%, 87.5% respectively. While in the high risk group (absolute risk > or = 20%) detection rate of abnormal SBP, FBG, TC, BMI was 7.31%, 3.4%, 37.74%, 59.26% respectively. CONCLUSIONS: The prediction models and simplified tools for estimating 10-year-risk of ICVD in Chinese can predict satisfactorily the occurrence of cardiovascular disease in Qingdao area.

Adult↗
PubMed2005

[Infiltration length of gastric cancer on giant sections].

BACKGROUND & OBJECTIVE: The resection boundary for gastric cancer is controversial. The study was designed to investigate gastric wall infiltration length of gastric cancer. METHODS: A total of 105 patients with gastric cancer who underwent gastrectomy at Cancer Center of Sun Yat-sen University from Apr. 2002 to Feb. 2004 were eligible. During gastrectomy, gastric wall lengths of 18 patients before traction (L1), after traction (L2), and after isolation (L3) were measured. Longitudinal specimen along the center of gastric cancer was fixed to measure the lengths of proximal and distal margins to the cancer. Giant section was observed under microscope to calculate the true infiltration length in proximal and distal margins according to the principle of the length changing uniformity. RESULTS: In the 18 specimens, L2 was significantly longer than L1 and L3 (P < 0.05); no significant difference was showed between L1 and L3 (P > 0.05). The infiltration length of localized gastric cancer, including early stage cancer, Borrmann I type cancer, and Borrmann II type cancer, was less than 2 cmû that of invasive gastric cancer, including Borrmann III type cancer and Borrmann IV type cancer, was less than 5 cm. CONCLUSION: The resection length for localized gastric cancer is at least 2 cm to tumor margin, and for invasive gastric cancer is at least 5 cm to tumor margin.

Adenocarcinoma↗