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X L Wang

Publications and source records attributed to X L Wang.

At least 37 records · Page 2Linked to original sources
PubMed2003

Purification, characterization of two peptides from Buthus martensi Karch.

A new peptide named Martentoxin I and an analogue Martentoxin were purified and characterized from the venom of Buthus martensi Karch. Martentoxin I consisted of 36 amino acid residues with molecular mass as 3908.0 Da determined by matrix-assisted laser desorption ionization time-of-flight-MS. The amino acid sequence was determined as GLIDVKCFASSECWTACKKVTGSGQGKCQNNQCRCY by Edman degradation. Martentoxin consisted of 37 amino acid residues with a molecular mass as 4055.3 Da and it showed highly sequence identity to Martentoxin I as FGLIDVKCFASSECWTACKKVTGSGQGKCQNNQCRCY. Estimation from circular dichroism spectra indicated Martentoxin I owned 18.0% alpha-helix, 53.0% beta-sheet structure and 3.9% turn while Martentoxin contained 13.3% alpha-helix, 64.3% beta-sheet structure and 1.1% turn. The toxicity assay showed both peptides had no toxic effects on mice up to the dose of 10 mg/kg. Electrophysiological studies showed that Martentoxin I and Martentoxin at the concentration of 1 microm significantly inhibited voltage-dependent Na+ current (INa) and voltage-dependent delayed rectifier K+ current (IK) but had no effects on transient K+ current (IA). Both interactions with Na+ and K+ channels were irreversible.

Amino Acid Sequence↗
PubMed2003

Arsenic trioxide induces apoptosis of rat hepatocellular carcinoma cells in vivo.

The aim of this work was to study the effect of arsenic trioxide (As2O3) on rat hepatocellular carcinoma (HCC), and investgate on the mechanisms of its antitumor effect. HCC was induced by chemocarcinogen diethylnitrosamine (DEN) in Wistar rats, that were then treated with As2O3 intraperitoneally in three different concentrations once a day for two weeks, and twice a week for another two weeks. The histological and ultrastructural changes in liver tissue were observed under microscope and electronic microscope on the 7th, 14th and 28th day after drug administration. The apoptosis and cellular dynamic parameters of tumor cells were observed by flow cytometry. The expression of bcl-2, bax, and proliferation cell nuclear antigen (PCNA) of rat liver cancer cells on the 7th day after drug administration was determined by using immunohistochemical technique. Treatment with As2O3 caused HCC cells death via both apoptotic and non-apoptotic mechanisms when the dose was high (5 mg.kg(-1)), while necrosis was rare and apoptosis was common when the dose was appropriate (1 mg.kg(-1)). This effect was obviously accompanied with accumulation of cells in G2/M phases (G2/M restriction). Many apoptotic cells were also found in G2/M phases. The expression intensity of bcl-2 or bax varied depending on the dose administrated. Downregulation of bcl-2/bax was observed, accompanied with upregulation of apoptosis. However, the ratio of bcl-2/bax and the percentage of apoptosis were not the utmost when the dose administered was the highest. In conclusion, these data demonstrate that As2O3 induces apoptosis of rat HCC cells, and it is closely associated with G2/M restriction when apoptosis reaches the top. Apoptosis can be observed in all three phases of cell cycle, but it is more common in G2/M phase when the dose is appropriate. It is suggested that arsenic trioxide may be an atypical cell cycle specific agent. Apoptosis of tumor cells is closely associated with down-regulation of the ratio of bcl-2/bax, but that may not be the only dominant factor.

Animals↗
PubMed2002

Lymphadenopathy at the medial epitrochlear region in cat-scratch disease.

Our objective was to describe the imaging features of lymphadenopathy at the medial epitrochlear region as frequently seen in cat-scratch disease (CSD) and to compare these features with those seen in non-CSD. Ten patients (four males and six females) presented with a subcutaneous soft tissue mass at the medial epitrochlear region. Three patients were younger than 15 years. Magnetic resonance imaging was performed in all patients. All lesions turned out to be regional lymphadenopathy instead of soft tissue neoplasm. They were caused by benign disorders in eight cases, including seven CSD and one other infection, and in two cases by metastatic disease. All lesions, except for three benign ones, were solitary. On MRI, high signal intensity (SI) strands in the surrounding soft tissue on T2-weighted images (WI) were present in all cases. Three cases of CSD showed homogeneous SI on both T1- and T2WI. After contrast administration, a moderate, homogeneous enhancement was seen. The other seven lesions, except for one metastasis, had both solid and liquid components. Liquid components showed high SI on T2WI without enhancement, whereas solid components had intermediate SI on T2WI and marked enhancement after contrast administration. Pathological findings in seven patients, including four with CSD, supported the tentative diagnosis made on MRI. One of two patients with CSD had positive serological test. Cat-scratch disease is a major cause of a soft tissue swelling at the medial epitrochlear region. Identification of lymphadenopathy and its presentation on MRI may be helpful in eliciting an animal-scratch history and achieving diagnostic and therapeutic aims in patients without primary cancer.

Adolescent↗
PubMed2002

Relationship between plasma homocysteine levels and brain atrophy in healthy elderly individuals.

The authors examined the association of total plasma homocysteine (Hcy) levels with measures of atrophy and white matter disease on MRI scans in 36 healthy elderly individuals. Hcy had a significant positive relationship with lateral ventricle-brain ratios in the anterior (r = 0.49) and middle (r = 0.43) ventricular regions as measures of central atrophy, but not with cortical atrophy or white matter hyperintensities. In a logistic regression analysis, elevated Hcy was a significant determinant of increased anterior ventricle-brain ratio (> or =0.34) after controlling for age, folate, B12, creatinine, and white matter disease (OR = 2.3; CI, 1.03-5.09).

Aged↗
PubMed2002

Nodular fasciitis: correlation of MRI findings and histopathology.

OBJECTIVE: To compare the histopathology of nodular fasciitis (NF) with the magnetic resonance imaging (MRI) findings in order to evaluate the basis of the MR signal characteristics. DESIGN AND PATIENTS: Ten patients with NF, nine females and 1 male, with an age ranging from 13 to 58 years (mean 26.8 years) were studied. MRI findings, available in all 10 patients, were compared with the histopathology in nine patients, and an area-to-area comparative study of the whole specimen section histopathology and MRI was performed in two patients. RESULTS: On the basis of an excisional biopsy or resection specimen, the nine lesions were classified into myxoid ( n=4), cellular ( n=3) and fibrous ( n=2) subtypes. Four myxoid lesions with a subcutaneous location showed a homogeneous SI comparable with muscle on T1-weighted images, high SI on T2-weighted images, and had homogeneous enhancement. One cellular lesion presented with homogeneous, slightly higher SI than muscle on T1-weighted images and inhomogeneous, high SI on T2-weighted images. Alcian blue stain of the whole specimen section revealed the lesion had two parts corresponding to different enhancement patterns on MRI. The blue-stained myxoid part showed markedly diffuse enhancement, while the non-stained cystic space had only peripheral enhancement. Two other cellular lesions had the same appearance on both T1- and T2-weighted images and showed inhomogeneous, diffuse enhancement. One fibrous subtype lesion presented with inhomogeneous, overall slightly higher SI than muscle on T1-weighted images, lower SI at the periphery and high SI in the center on STIR images and only peripheral enhancement. Microscopy and CD-31 staining of the lesion showed more extracellular matrix, with poor vascularity in the center and more collagenous matrix with higher vascularity at the periphery. CONCLUSION: Although similar findings were found in some lesions, the large histologic variability of NF hampers the definition of a prototype of NF on MRI. However, the MRI appearance of the myxoid subtype is rather characteristic. Histologic findings reflect the different SI characteristics and enhancement pattern on MRI.

Adolescent↗
PubMed2002

Characterizing and comparing risks of polycyclic aromatic hydrocarbons in a Tianjin wastewater-irrigated area.

A probability risk assessment was conducted to characterize the ecotoxicity of three polycyclic aromatic hydrocarbons (PAHs), including benzo[a]pyrene, fluoranthene, and phenanthrene, to various species in a wastewater-irrigated area of Tianjin, China. The relative risk of these chemicals was investigated using joint risk probability distribution curves, which were generated based on the distributions of exposure and acute toxicity data. Risk at various exposure levels was discussed. The results indicated that among the three PAHs studied, the overall risk of phenanthrene was the highest, with that of benzo[a]pyrene the lowest, due mainly to their exposure concentrations. For lower exposure levels at which the percentage of species affected was less than 20%, the risk associated with benzo[a]pyrene was clearly higher than that of the other two chemicals.

China↗
PubMed2002

Effect of vitamin C on pulmonary hypertension and muscularisation of pulmonary arterioles in broilers.

1. Three hundred and eighty 1-day-old Arbor Acres broilers were divided into control (A) and experimental (B, C, D, and E) groups. 2. After 14 d of age the experimental groups were subjected to a cool temperature challenge by lowering the temperature 1 to 2 degrees C per day down to 12 degrees C, and maintaining this temperature until 7 weeks of age. 3. At the same time, 1.5 mg/kg 3,3,5-triiodothyronine (T3) was added to the diet of groups D and E, and 500 mg/kg ascorbic acid (vitamin C) to the diet of groups C and E. 4. The incidence of pulmonary hypertension syndrome (PHS), body weight gain and feed intake were measured weekly. Lung and blood samples were collected weekly from 10 birds per group beginning on d 14, and the percentage of thick-walled peripheral lung vessels (% TWPV) and packed cell volume (PCV) were determined. 5. The lower ambient temperature and diets supplemented with T3 increased PHS incidence and % TWPV and decreased body weight gain. 6. There was an increase in PCV after 5 weeks of age under lower ambient temperature 3 and the PCV values 14 were also significantly increased by T3. 7. Vitamin C supplementation reduced PHS incidence and % TWPV but did not change packed cell volume, body, weight gain, feed intake, or feed conversion. 8. It is concluded that vitamin C reduced PHS and the associated muscularisation of pulmonary arterioles induced by exposing broilers to cool environmental temperatures and feeding them with T3.

Animals↗
PubMed2001

Automobile exhaust particle-induced apoptosis and necrosis in MRC-5 cells.

To study the effect of particulate extracts (PE) collected from a heavy traffic road in Lanzhou City, on MRC-5 cell apoptosis, and to explore the toxicity action of PE and its mechanism. Cultured MRC-5 cells were incubated in the extracts of different concentrations. Inhibition of proliferation was measured with a colorimetric 3-[4,5-dimethyl thiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Morphological assessment of apoptosis was performed with fluorescence microscopy and electronic microscopy. Extracted DNA from the cells was electrophoresed on agarose gel in order to observe DNA fragmentation. The amount of apoptotic cells was measured by flow cytometry. The results indicated that exposure of exponentially growing MRC-5 cells exposed to PE 5-160 microg l(-1) for 24-96 h resulted in dose- and time-dependent reduction of survival of MRC-5 cells. After treatment with PE, markedly morphological changes of MRC-5 cells including "apoptotic bodies", were observed with a fluorescence microscope. Agarose gel electrophoresis of DNA from the cells treated with PE for 48 and 72 h revealed a "ladder" pattern. PE induced apoptosis in low doses but necrosis in high doses. Apoptotic rates were 12.95, 17.40 and 29.80% after treatment with PE 5, 10, and 20 microg l(-1), respectively. A typical sub-diploid apoptosis peak was demonstrated in MRC-5 cells treated with PE. A significant dose-effect response and time-effect correlation could be found between apoptosis rates and PE. All results confirmed that the PE could induce and accelerate apoptosis in low doses but necrosis in high doses.

Air Pollutants↗
PubMed2001

Cigarette smoke activates caspase-3 to induce apoptosis of human umbilical venous endothelial cells.

We explored an hypothesis that cigarette smoking-induced endothelial injury is mediated by accelerated apoptosis by treating human endothelial cells with cigarette smoke extracts (CSE). In cells treated with an increasing doses of CSE (0.005-0.03 cigarette equivalents/mL), we found a dose-dependent increase in the proportion of endothelial cells stained positive for apoptotic changes (8.3 +/- 0.7 to 50.7 +/- 2.2%, P < 0.01), accompanied by changes in caspase-3 activities and p53 protein levels. We suggest that excessive endothelial apoptosis may contribute to cigarette smoke-induced endothelial dysfunction and hence atherogenesis.

Apoptosis↗
PubMed2001

Cytomegalovirus inhibits p53 nuclear localization signal function.

Endothelial cells (EC) infected with the VHL strain of cytomegalovirus (CMV) are resistant to p53-mediated apoptosis, which may be relevant to EC dysfunction and atherogenesis. This resistance to apoptosis may be mediated by cytoplasmic sequestration of p53, which functions only in the nucleus. We explored the hypothesis that CMV sequesters p53 in the cytoplasm by blocking p53 nuclear localization signal (NLS) function. We transfected VHL CMV infected EC with recombinant p53 NLSI conjugated with chicken muscle pyruvate kinase (PK) plasmid. NLSI is responsible for 90% of p53 nuclear localization, and PK is not normally translocated to the nucleus after cytoplasmic production. Thus it cannot be localized in the nucleus without the assistance of the artificial NLSI. A double-labeling immunofluorescence staining method was used to identify the localization of p53 NLSI-conjugated PK in CMV-infected EC. We found that CMV infection sequesters PK and p53 in the cytoplasm by blocking NLSI function. This inactivation of NLSI function is dependent upon infection stage; it occurs only in the early and late phases and not the immediate early phase of infection. These findings may be relevant to endothelial dysfunction and initiation of atherogenesis. Our study also suggests a novel mechanism of the p53 inactivation by virus, which may be important for atherogenesis and tumorgenesis.

Animals↗
PubMed2001

Tumor necrosis factor receptor 2 gene (TNFRSF1B) in genetic basis of coronary artery disease.

Tumor necrosis factor (TNF)-alpha has been implicated in pathophysiological processes in coronary artery disease (CAD). TNF receptor 2 is of particular interest in mediating such effects. The gene for this receptor (TNF-RSF1B) has, moreover, been implicated in hypertension, elevated cholesterol and insulin resistance. TNFRSF1B is thus a worthy candidate in studies of the genetic basis of CAD. We therefore conducted a case-control study of a microsatellite marker with five alleles (CA13-CA17) in intron 4 of TNFRSF1B in 1006 well-characterized white patients with angiographically confirmed CAD and a control group of 183 healthy subjects. We found a strong association of the TNFRSF1B marker with CAD (chi2=40, P=0.00000069). The frequency of the CA16 allele was 33% in CAD vs. 21% in control (odds ratio, OR, to have CAD for presence vs. absence of CA16 allele in CA16 homozygotes was 4.5, 95% CI 2.1-9.4, P<0.0001; in CA16 heterozygotes OR was 1.3, 95% CI 0.94-1.89, P=0.10). The frequency of the major allele (CA15) was 43% in CAD vs. 56% in controls (in CA15 homozygotes OR 0.33, 95% CI 0.20-0.52, P<0.0001; in heterozygotes OR 0.41, 95% CI 0.26-0.63, P<0.0001). In a stepwise logistic regression model the CA16 allele was significantly associated with overweight (OR 1.44, 95% CI 1.0-1.9, P=0.027). Apolipoprotein A-I was elevated (P<0.0001), as was high-density lipoprotein (P=0.098), and severity of angina was decreased (P=0.024) as a function of genotype. Plasma soluble (s) TNF-R2 was 5.1 +/- 0.1 ng/ml in CAD vs. 3.2 +/- 0.1 in control (P<0.0001), 5.2 +/- 0.1 in the presence vs. 4.6 +/- 0.2 in the absence of vessel disease (P=0.009), and rose with increasing severity of angina: 4.2 +/- 0.2 (no angina), 5.0 +/- 0.1 (stable angina), 5.4 +/- 0.2 (unstable angina; P=0.003). sTNF-R2 was correlated with age, cholesterol, creatinine, fibrinogen, transforming growth factor beta and homocysteine and was influenced by TNFRSF1B genotype. Thus genetic variation in or near the TNFRSF1B locus may predispose to CAD.

Adult↗
PubMed2001

A juvenile ankylosaur from China.

Juvenile ankylosaur specimens are very rare. A new ankylosaur, Liaoningosaurus paradoxus gen. et sp. nov., is described based on a beautifully preserved juvenile ankylosaur specimen from the famous Yixian Formation of Liaoning, China. Liaoningosaurus has a large bony plate (somewhat shell-like) shielding the abdomen. This discovery represents the first record of such a structure among dinosaurs. Although it has a number of distinct features seen in the family Ankylosauridae, a cladistic analysis placed Liaoningosaurus in the sister-family Nodosauridae. The 'intermediate' status of this taxon between the two ankylosaur families further supports the monophyly of Ankylosauria. This finding also documents the smallest known ankylosaur specimen and first complete nodosaurid specimen from Asia.

Animals↗
PubMed2001

Analytical methodologies for aluminium speciation in environmental and biological samples--a review.

It is recognized that aluminium (Al) is a potential environmental hazard. Acidic deposition has been linked to increased Al concentrations in natural waters. Elevated levels of Al might have serious consequences for biological communities. Of particular interest is the speciation of Al in aquatic environments, because Al toxicity depends on its forms and concentrations. In this paper, advances in analytical methodologies for Al speciation in environmental and biological samples during the past five years are reviewed. Concerns about the specific problems of Al speciation and highlights of some important methods are elucidated in sections devoted to hybrid techniques (HPLC or FPLC coupled with ET-AAS, ICP-AES, or ICP-MS), flow-injection analysis (FIA), nuclear magnetic resonance (27Al NMR), electrochemical analysis, and computer simulation. More than 130 references are cited.

Aluminum↗
PubMed2001

Low-grade chondrosarcoma vs enchondroma: challenges in diagnosis and management.

A 28-year-old man presented with a swelling at the right thoracic wall. Computed tomography showed an aggressive process involving the cortex of the rib with concomitant soft tissue mass. However, a needle biopsy specimen revealed an enchondroma and consequently the physician decided to apply a "wait-and-see" strategy. After 3 years of careful follow-up by MR imaging, the patient complained of subtle enlargement of the lesion, which was later confirmed on repeated CT scan. Despite an aggressive appearance on control MR imaging, histopathological examination after incisional biopsy could not differentiate between enchondroma and low-grade chondrosarcoma. Wide excision including previous biopsy trajectory was performed. Diagnosis of a low-grade (grade I) chondrosarcoma was made on findings of the excisional specimen and seeding of cartilage tissue along the previous incisional biopsy trajectory was found.

Adult↗
PubMed2001

Ultra stable tuning fork sensor for low-temperature near-field spectroscopy.

We report on a distance control system for low-temperature scanning near-field optical microscopy, based on quartz tuning fork as shear force sensor. By means of a particular tuning fork-optical fiber configuration, the sensor is electrically dithered by an applied alternate voltage, without any supplementary driving piezo, as done so far. The sensitivity in the approach direction is 0.2nm, and quality factors up to 2850 have been reached. No electronic components are needed close to the sensor, allowing to employ it in a liquid He environment. The system is extremely compact and allows for several hours of stability at 5 K.

Journal Article↗
PubMed2001

Genetic contributions to plasma total antioxidant activity.

Oxidative stress plays important roles in a wide spectrum of pathological processes, such as atherosclerosis. Although several environmental factors are documented to influence redox metabolism, relatively little is known about genetic effects. In the present study, we evaluated genetic contributions to variation in plasma total antioxidant status (TAS), a measure of peroxyl-scavenging capacity, in 1337 members of 40 Mexican American families. TAS levels were significantly lower in women than in men (1.675+/-0.004 versus 1.805+/-0.005 mmol/L, respectively; P<0.001), and there was a significant decline of TAS levels with age in men but not in women (P<0.01 for the interaction). Quantitative genetic analysis indicated the heritability of TAS levels to be 0.509+/-0.052; ie, approximately 51% of the residual variance (after covariate adjustment) in TAS levels was due to the additive effects of genes (P<0.001). We have further observed a significant gene-by-smoking interaction (P<0.05). Additive genetic effects account for 83% of the residual phenotypic variance in TAS levels among smokers, but they account for only 49% in nonsmokers. However, genes contributing to TAS variation are the same in smokers and nonsmokers. Our study for the first time demonstrates that TAS, an indicator of redox homeostasis, is under strong genetic control, especially among smokers. With appropriate tools, such as genome screening, it should be possible to localize genes that regulate redox homeostasis and, ultimately, identify the DNA sequence variants predisposing subjects to oxidative damage.

Adolescent↗
PubMed2001

TNFRSF1B in genetic predisposition to clinical neuropathy and effect on HDL cholesterol and glycosylated hemoglobin in type 2 diabetes.

OBJECTIVE: Genetic variation in the tumor necrosis factor (TNF) receptor 2 gene (TNFRSF1B) has shown association with insulin resistance in type 2 diabetes, hypercholesterolemia, coronary artery disease, and essential hypertension. Here we tested the TNFRSF1B marker used in the latter studies in type 2 diabetes patients. RESEARCH DESIGN AND METHODS: A case-control study of a microsatellite marker with five alleles (CA13- CA17) in intron 4 of TNFRSF1B was performed in 357 well-characterized white patients and 183 healthy control subjects. RESULTS: The CA16 allele was associated with clinical neuropathy (frequency = 27% in 69 patients with the condition versus 16% in 230 subjects without the condition; chi2 = 9.0, P = 0.011; odds ratio = 2.1 [95% CI 1.2-3.8]). No association was seen with other complications or diabetes itself. The CA16 allele tracked with elevation plasma HDL cholesterol (1.3 +/- 0.2, 1.2 +/- 0.4, and 1.1 +/- 0.2 for CA16/CA16, CA16/-, and -/-, respectively; n = 9, 110, and 218, respectively; P = 0.009) and reduction in plasma glycosylated hemoglobin (6.6 +/- 0.3, 8.3 +/- 0.2, and 8.1 +/- 0.1 for CA16/CA16, CA16/-, and -/-, respectively; n = 9, 102, 205, respectively; P = 0.007) Significance remained after Bonferroni correction for multiple testing. CONCLUSIONS: Genetic variation in or near TNFRSF1B may predispose clinical neuropathy, reduced glycosylated hemoglobin, and increased HDL cholesterol in type 2 diabetes patients. The latter could be part of a protective response.

Aged↗