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Biomedical subjects

W Xu

Publications and source records attributed to W Xu.

At least 127 records · Page 7Linked to original sources
PubMed2001

Primary structure and expression of a 24-kD vacuolar protein (VP24) precursor in anthocyanin-producing cells of sweet potato in suspension culture.

A 24-kD vacuolar protein (VP24) accumulates abundantly in intravacuolar pigmented globules in anthocyanin-containing sweet potato (Ipomoea batatas) cells in suspension culture. A cDNA clone encoding VP24 was isolated from a cDNA library constructed from light-irradiated suspension-cultured cells. Sequence analysis revealed that a 2.9-kbp VP24 cDNA encodes a protein of 893 amino acid residues with a molecular mass of 96.3 kD. According to the deduced amino acid sequence of VP24 cDNA, VP24 is probably synthesized as a large precursor protein with an N-terminal extension composed of a signal peptide and a propeptide, plus the polypeptide of the mature VP24 and its C-terminal propeptide, which contains the multiple transmembrane domains. A search in the ProDom database revealed the mature VP24 domain belongs to the zinc metalloprotease family. Northern analysis revealed that the single 2.9-kb VP24 mRNA increases rapidly after light irradiation, whereas VP24 mRNA was undetectable in the dark-cultured cells or in the presence of a high concentration of 2,4-dichlorophenoxyacetic acid. Light-induced VP24 gene expression closely correlated with the accumulation of anthocyanin in the vacuoles. These results suggested that proteins derived from the VP24 precursor protein may be involved in vacuolar transport and/or accumulation of anthocyanin synthesized in the cytosol.

Amino Acid Sequence↗
PubMed2001

3,9-Bis(dicyanomethylene)-2,4,8,10-tetrathiaspiro[5.5]undecane.

The title compound, 2,2'-(2,4,8,10-tetrathiaspiro[5.5]undecane-3,9-diylidene)bis(propanedinitrile), C(13)H(8)N(4)S(4), has been designed and synthesized for use as a potential new organic molecular electronic material. The spiro-annulated structure has twofold symmetry and is formed by two equal push-pull ethylene units, with the cycloalkylthio groups as electron donors and the cyano groups as electron acceptors. The intermolecular S.N non-bonded separation within a layer in the lattice is 3.296 (6) A, indicating a strong intermolecular interaction between the cyano groups and the S atoms, while the S atoms in two neighbouring molecules have a shortest S.S contact of 3.449 (3) A. In addition, attractive C-H.N and C-H.S interactions bridge adjacent molecules either within a layer or between layers. In short, these four types of intermolecular interactions combine to form an extended three-dimensional network in the lattice, resulting in a highly ordered array of molecular packing.

Journal Article↗
PubMed2001

Yeast PalA/AIP1/Alix homolog Rim20p associates with a PEST-like region and is required for its proteolytic cleavage.

The Saccharomyces cerevisiae zinc finger protein Rim101p is activated by cleavage of its C-terminal region, which resembles PEST regions that confer susceptibility to proteolysis. Here we report that Rim20p, a member of the broadly conserved PalA/AIP1/Alix family, is required for Rim101p cleavage. Two-hybrid and coimmunoprecipitation assays indicate that Rim20p binds to Rim101p, and a two-hybrid assay shows that the Rim101p PEST-like region is sufficient for Rim20p binding. Rim101p-Rim20p interaction is conserved in Candida albicans, supporting the idea that interaction is functionally significant. Analysis of Rim20p mutant proteins indicates that some of its broadly conserved regions are required for processing of Rim101p and for stability of Rim20p itself but are not required for interaction with Rim101p. A recent genome-wide two-hybrid study (T. Ito, T. Chiba, R. Ozawa, M. Yoshida, M. Hattori, and Y. Sakaki, Proc. Natl. Acad. Sci. USA 98:4569-4574, 2000) indicates that Rim20p interacts with Snf7p and that Snf7p interacts with Rim13p, a cysteine protease required for Rim101p proteolysis. We suggest that Rim20p may serve as part of a scaffold that places Rim101p and Rim13p in close proximity.

DNA-Binding Proteins↗
PubMed2001

Mice with very low expression of the vesicular monoamine transporter 2 gene survive into adulthood: potential mouse model for parkinsonism.

We have created a transgenic mouse with a hypomorphic allele of the vesicular monoamine transporter 2 (Vmat2) gene by gene targeting. These mice (KA1) have profound changes in monoamine metabolism and function and survive into adulthood. Specifically, these animals express very low levels of VMAT2, an endogenous protein which sequesters monoamines intracellularly into vesicles, a process that, in addition to being important in normal transmission, may also act to keep intracellular levels of the monoamine neurotransmitters below potentially toxic thresholds. Homozygous mice show large reductions in brain tissue monoamines, motor impairments, enhanced sensitivity to dopamine agonism, and changes in the chemical neuroanatomy of the striatum that are consistent with alterations in the balance of the striatonigral (direct) and striatopallidal (indirect) pathways. The VMAT2-deficient KA1 mice are also more vulnerable to the neurotoxic effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in terms of nigral dopamine cell death. We suggest that the mice may be of value in examining, long term, the insidious damaging consequences of abnormal intracellular handling of monoamines. On the basis of our current findings, the mice are likely to prove of immediate interest to aspects of the symptomatology of parkinsonism. They may also, however, be of use in probing other aspects of monoaminergic function and dysfunction in the brain, the latter making important contributions to the pathogenesis of schizophrenia and addiction.

Animals↗
PubMed2001

Characterization of surface and photooxidative properties of supported metal oxide photocatalysts using solid-state NMR.

In situ solid-state NMR (SSNMR) methodologies have been used to investigate the surface properties and photooxidative reactivities of a number of metal oxide photocatalysts. Adsorption of ethanol on single monolayers of TiO2, SnO2, V205, and WO3 supported on porous Vycor glass results in the formation of hydrogen-bonded ethanol species and metal-bound ethoxide species. The chemical shift of the metal-bound ethoxide species varies with the metal oxide catalyst while the chemical shift of the hydrogen-bonded species is independent of the metal oxide. X-ray powder diffraction, UV-VIS spectroscopy, and SSNMR investigations of ethanol adsorption show that increasing the number of monolayers of TiO2 on the Vycor surface changes the morphology of the catalyst from amorphous at a single monolayer coverage to anatase at a four monolayer coverage. The rate of photocatalytic oxidation of ethanol, acetone, and 2-propanol also increases with increasing TiO2 monolayer coverage.

2-Propanol↗
PubMed2001

Human endothelial cells maintain anti-aggregatory activity for platelets during apoptosis.

Despite evidence of elevated levels of tissue factor and platelet binding by apoptotic endothelial cells, microthrombi do not appear to be associated with apoptotic endothelium and this suggests maintained anti-aggregatory activity for platelets. We report that anti-aggregatory activity is maintained by apoptotic endothelium obtained by serum and or matrix deprivation, which we propose as models for apoptotic endothelial cells released during microvascular remodelling and traumatic detachment respectively. Both apoptotic and non-apoptotic endothelium had strong anti-aggregatory activity for platelets stimulated with either ADP or thrombin. Inhibition experiments using L-NAME and indomethacin indicated a role for nitric oxide and prostacyclin in this activity. Experiments with latex beads further confirmed that inhibited platelet aggregation by endothelium was not merely a non-specific phenomenon. These data support the idea that EC maintain active antithrombotic activity during apoptosis, consistent with maintained urokinase levels and canalicular fragmentation reported elsewhere.

Adenosine Diphosphate↗
PubMed2001

[Chemical assessment of mutagenicity of halohydrocarbons: FTIR, UV spectrum characteristics of guanine-halohydrocarbon adducts].

Determination and identification of guanine-halohydrocarbon adduct isomers were carried out by high performance liquid chromatography (HPLC) and Fourier transform infrared spectroscopy (FTIR). The experimental results showed that the UV spectral overlay of O6-guanine adducts retrieved after HPLC at 260-270 nm. The UV spectra of N-side adducts are similarly between 240-250 nm. After thin layer chromatographic separation (silica gel-GF254), the all IR spectra of the N-side adducts of guanine with different halohydrocarbons showed a absorption near 1700 cm-1 assigned the characteristic peak of C=O. The IR spectra among the adducts of O6-guanine with different halohydrocarbons are quite similar.

Chromatography, High Pressure Liquid↗
PubMed2001

Cytoplasmic expression of ribozyme in zebrafish using a T7 autogene system.

A cytoplasmic ribozyme expression system, based on codelivery of a ribozyme vector, a T7 autogene vector, and T7 RNA polymerase (RNAP), has been developed and used to generate a specific phenotype in zebrafish by targeting a no tail (ntl) mRNA. The expression of the no tail ribozyme sequence is under the control of a tandem of two promoters: The T7 promoter and an adenoviral va 1 (pol III) promoter. The coinjection of the ribozyme vector pT7vaRz, the T7 autogene vector pT7T7, and the T7 RNAP resulted in rapid synthesis of the ribozyme against the ntl mRNA in the cytoplasm of the injected zebrafish embryos, generating no tail phenotypes in up to 10-20% of the injected embryos. The phenotypic change rates have been found to be related to the concentrations of the plasmid vectors and T7 RNAP injected and to the ratios of the three injected components. This cytoplasmic ribozyme expression system may be useful for efficiently targeting other mRNA and for various biomedical applications. These potential applications may include rapid identification of biological functions of novel genes from zebrafish and humans based on partial gene sequence information and gene therapy of genetic and acquired diseases.

Adenoviridae↗
PubMed2001

[The composition of PAHs in fly ash in Beijing].

The composition of polycyclic aromatic hydrocarbons (PAHs) in fly ash samples which were gathered from manufacturing district of Shijingshan district and residential quarters of Haidian district were analyzed using HPLC/MS technique. The differences of the contents of PAHs in fly ash samples from manufacturing district and residential quarters were compared. The changes of the contents of PAHs of different seasons were discussed. In this study 135 PAHs including 55 large PAHs whose molecular weights are greater than 300u were detected in fly ash sample from manufacturing district. HPLC/MS offset the deficiency of GC/MS which can not determine large PAHs directly and can reflect the distribution of PAHs in fly ash more roundly.

Carbon↗
PubMed2001

[The association between SA gene and essential hypertension in Han Chinese].

OBJECTIVE: To evaluate the linkage of SA gene locus to essential hypertension(EH) in affected Han Chinese sib pairs and to ascertain the association of SA gene CT79 polymorphism with essential hypertension in Han Chinese hypertensives. METHODS: In Han Chinese at Shanghai, 96 random individuals, 80 essentially hypertensive sib pairs with hypertensive family history, 200 essential hypertensives with hypertensive family history and 200 normotensive control(NC) subjects without such family history were enrolled in these serial studies. MF-PCR-SSCP technique was applied to detect the frequency distributions of SA gene microsatellite D16S3046, D16S3136 and D16S3068. The linkage of SA gene locus to essential hypertension was analyzed by Green's IBS for affected siblings. SA gene variant was screened by PCR-SSCP- silver staining and confirmed by DNA sequencing, then an association study was performed to determine whether such variant was associated with essential hypertension. RESULTS: The frequency distributions of SA gene microsatellites D16S3046, D16S3136 and D16S3068 were of high polymorphism. The polymorphism information contents of D16S3046, D16S3136 and D16S3068 were 0.86, 0.82 and 0.80, and the heterozygosities 0.88, 0.71 and 0.77. The linkage of SA gene locus to essential hypertension was not observed; the linkage analysis t values of D16S3046,D16S3136 and D16S3068 were 0.972, 0.622 and 0.236, and the P values 0.384, 0.543 and 0.871, respectively. The C two head right arrow T substitution was confirmed, but there was no association of such variant with essential hypertension. The frequency distributions of genotypes and alleles in the hypertensive group were not significantly different from those in the normotensive group (P>0.05). CONCLUSION: SA gene is not linked to or associated with essential hypertension in Han Chinese. SA gene may not be a susceptible gene contributing to the development of essential hypertension in Han Chinese.

Adult↗
PubMed2001

Glucocorticoid receptor and heat shock protein 90 in peripheral blood mononuclear cells from asthmatics.

OBJECTIVE: To investigate the expression of glucocorticoid receptor (GR) and heat shock protein 90 (HSP90) mRNA in peripheral blood mononuclear cells (PBMCs) from steroid-sensitive (SS), steroid-dependent (SD) and steroid-resistant (SR) asthmatics patients, and to evaluate the role of GR and HSP90 in the pathogenesis of SR. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the expressions of GR and HSP90 mRNA in PBMC stimulated with IL-2 and/or IL-4 from 10 normal volunteers, 10 SS, 5 SD and 6 SR patients. RESULTS: The expressions of GR and HSP90 mRNA were the highest in PBMC from SR patients (0.730 +/- 0.171 and 1.122 +/- 0.165, respectively) compared with the normals (P < 0.05). The second was from SS patients (0.359 +/- 0.350 and 0.885 +/- 0.250, respectively). The lowest was from the SD patients (0.017 +/- 0.008 and 0.078 +/- 0.039, respectively). The ratio of HSP90/GR in SR was significantly lower than that in the others, and it suggested that the expression of HSP90 mRNA was not sufficient in this group of patients. When PBMC from SS, SD and SR was incubated with IL-2 or IL-4 alone, no changes in GR and HSP90 mRNA expression were observed. While incubated with combination of IL-2 and IL-4, a significantly higher expression of GR mRNA was observed in all asthmatics, and a significantly higher expression of HSP90 mRNA was observed only in SS and SD patients. CONCLUSION: The lowering of HSP90/GR ratio may be one of the causes of SR. IL-2 and IL-4 may play roles in the imbalance of HSP90/GR.

Adult↗
PubMed2001

[Claude Bernard, founder of experimental physiology].

Claude Bernard was a famous French physiologist and philosopher in the 19th century. His experimental researches almost involved all fields of physiology. It is generally recognized by physiologists that in the research of Bernard in the digestion of pancreas, glucogenesis in the liver, and the vasomotor mechanism and the mechanism of action of curari and carbon monoxide were all at the lead. His researches established the foundation for modern physiology, modern biochemistry and the works of Pavlov, and were the initiation of experimental physiology.

France↗
PubMed2001

[The postburn changes of the plasma levels of PGE2 and TNF alpha in burn patients].

OBJECTIVE: To explore the postburn changes of the plasma levels of PGE2 and TNF alpha and their relationship with burn severity and sepsis. METHODS: Twenty-four burn patients were enrolled in the study and were randomly divided into four groups based on burn area and sepsis in reference to normal group (10 healthy adult volunteers). The plasma levels of PGE2 and TNF alpha at different postburn time points in all burn patients and in healthy volunteers were determined by radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA), respectively. RESULTS: The postburn plasma PGE2 level increased in most patients but decreased in the patients with major burn or sepsis, even to the level lower than that in normal control. On the other hand, the postburn plasma TNF alpha level increased in all patients, especially obvious in those with sepsis. And the changes were not correlated to burn area and postburn time. Moreover, the postburn plasma TNF alpha level was negatively correlated to that of PGE2. CONCLUSION: Decreased postburn plasma PGE2 level was correlated to high incidence of burn sepsis. And PGE2 might down-regulate TNF alpha production.

Adolescent↗
PubMed2001

[The expression and clinical significance of proliferative antigen Ki-67 and apoptosis-antagonizing antigen Bcl-2 in non-Hodgkin's lymphoma].

OBJECTIVE: To evaluate the expression of proliferative antigen Ki-67 and apoptosis-antagonizing protein Bcl-2 as well as their clinical significance in non-Hodgkin's lymphoma (NHL). METHODS: Ki-67 antigen and Bcl-2 protein were measured by immunohistochemistry on paraffin -embedded slices in 35 cases of NHL. RESULTS: (1) The level of Ki-67 expression in low grade NHL was lower than that in high grade NHL (P < 0.01),while Bcl-2 expression in lower grade NHL was higher than that in high grade (P < 0.01). (2) The level of Bcl-2 expression in B cell NHL was higher than that in T cell NHL (P < 0.02), but there was no difference in the expression of Ki-67. (3) The level of Bcl-2 expression in remission group was lower than that in non-remission group after the first course of chemotherapy, but there was no significant difference in Ki-67 expression. (4) The survival time was longer in the group with Ki-67 < or = 20% than that in the group with Ki-67 > 20%, but there was no significant difference of survival time between the high and low expression group of Bcl-2. CONCLUSIONS: The level of Ki-67 and Bcl-2 expression was closely related with the grade of malignant and the prognosis of NHL. They were a pair of useful markers for understanding the generation and prognosis of NHL.

Adolescent↗
PubMed2001

[Glucocorticoid receptor and HSP 90 mRNA expression in peripheral blood mononuclear cell from steroid resistant asthmatics].

OBJECTIVE: To investigate the expression of glucocorticoid receptor (GR) and HSP 90 mRNA in peripheral blood mononuclear cells (PBMC) from steroid-sensitive asthma (SS), steroid-dependant asthma (SD) and steroid-resistant asthma (SR) and assess the role of GR and HSP 90 in the pathogenesis of SR. METHODS: With reverse transcription-polymerase chain reaction (RT-PCR), expression of GR and HSP 90 mRNA were detected in PBMC without or with IL-2 and (or) IL-4 stimulation from 10 normal volunteers, 10 SS, 5 SD and 6 SR patients. RESULTS: Expression of GR and HSP 90 mRNA in PBMC was the highest in SR group (0.730 +/- 0.171, 1.122 +/- 0.165 respectively), then in SS group (0.359 +/- 0.350, 0.885 +/- 0.250 respectively), the lowest in SD group (0.017 +/- 0.008, 0.078 +/- 0.039 respectively). The expression of GR and HSP 90 mRNA in PBMC from normal volunteers was 0.052 +/- 0.013 and 0.362 +/- 0.101 respectively. The difference of the expression of GR or HSP 90 was significant between each group (P < 0.05). The ratio of HSP 90/GR in normal volunteers, SS, SD and SR patients was 7.15 +/- 1.84, 8.39 +/- 7.95, 5.51 +/- 3.30 and 1.57 +/- 0.18 respectively. HSP 90/GR in SR was significant lower than those of the others, suggesting that the expression of HSP 90 mRNA was in sufficient in this group. When PBMC were incubated with combination of IL-2 and IL-4, a significant higher over expression of GR mRNA was observed in all asthmatic group and a significant higher expression of HSP 90 mRNA was observed only in SS and SD groups but not in SR group. CONCLUSION: The low expression of HSP 90 mRNA and the lowering ratio of HSP 90/GR mRNA may be related to the pathogenesis of SR. Different response to IL-2 and IL-4 may play a role in the development of HSP 90/GR imbalance.

Adult↗
PubMed2001

Peri-operative treatment of most severely head-injured patients.

OBJECTIVE: To summarize the peri-operative experience from 53 patients with traumatic head injuries with GCS score 3-5. METHODS: Fifty-three most severely head-injured patients with GCS score 3-5 were admitted to our department and treated operatively from Oct. 1994 to Jun. 1998 and the data were analyzed retrospectively. RESULTS: Thirty-seven cases (69.8%) survived, among them 28 (52.8%) had a good recovery or moderate disability, and 9 (17%) had severe deficits. The other 16 (30.2%) died after therapy. CONCLUSIONS: The prognosis of most severely head-injured patients could be improved by peri-operative treatment including premedical care, early evacuation of intracranial hematoma with large decompressive craniectomies, intracranial hypertension monitoring, moderate hypothermia therapy, effective prevention and treatment of cerebral vasospasm and complications.

Adolescent↗
PubMed2001

[The comparison of two methods to predict the post-operative visual acuity of cataractous patients].

OBJECTIVE: To study the accurate methods to predict the post-operative visual acuity of cataractous patients with different degrees of opaque lenses. METHODS: Visual electrophysiological methods and retinometer were used to evaluate the visual function after phacoemulsification and intraocular lens implantation in 152 cases (152 eyes). The regressive analyses between the post-operative best corrected visual acuity (BCVA) and each of the following results: the pre-operative flash electroretinogram (F-ERG), flash visual evoked potentials (F-VEP) and potential visual acuity (PVA) were performed, respectively. RESULTS: More obvious linear-relationship was shown between PVA and BCVA (r = 0.654) than that between the combination of b wave's amplitude of F-ERG with wave's amplitude of F-VEP and BCVA (r = 0.528) in the patients with partial opaque lenses. Obvious linear-relationship between the combination of the F-ERG with F-VEP values and BCVA (r = 0.487) and no obvious relationship between the potential visual acuity and BCVA (r = 0.049) were shown in the patients with near complete/complete opaque lenses. CONCLUSION: Both visual electrophysiological and retinometric detection, especially the latter one, can predict the post-operative visual acuity of the patients with partial opaque lenses accurately. Visual electrophysiological detection can predict the post-operative visual acuity of cataractous patients with near complete/complete opaque lenses accurately but retinometric detection can not.

Adolescent↗