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Biomedical subjects

X Wei

Publications and source records attributed to X Wei.

At least 55 records · Page 3Linked to original sources
PubMed2000

Hrs interacts with sorting nexin 1 and regulates degradation of epidermal growth factor receptor.

Hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) is a mammalian homologue of yeast vacuolar protein sorting (Vps) protein Vps27p; however, the role of Hrs in lysosomal trafficking is unclear. Here, we report that Hrs interacts with sorting nexin 1 (SNX1), a recently identified mammalian homologue of yeast Vps5p that recognizes the lysosomal targeting code of epidermal growth factor receptor (EGFR) and participates in lysosomal trafficking of the receptor. Biochemical analyses demonstrate that Hrs and SNX1 are ubiquitous proteins that exist in both cytosolic and membrane-associated pools, and that the association of Hrs and SNX occurs on cellular membranes but not in the cytosol. Furthermore, endogenous SNX1 and Hrs form a approximately 550-kDa complex that excludes EGFR. Immunofluorescence and subcellular fractionation studies show that Hrs and SNX1 colocalize on early endosomes. By using deletion analysis, we have mapped the binding domains of Hrs and SNX1 that mediate their association. Overexpression of Hrs or its SNX1-binding domain inhibits ligand-induced degradation of EGFR, but does not affect either constitutive or ligand-induced receptor-mediated endocytosis. These results suggest that Hrs may regulate lysosomal trafficking through its interaction with SNX1.

Amino Acid Sequence↗
PubMed2000

Targeting the chromatin-remodeling MSL complex of Drosophila to its sites of action on the X chromosome requires both acetyl transferase and ATPase activities.

Dosage compensation in Drosophila is mediated by a multiprotein, RNA-containing complex that associates with the X chromosome at multiple sites. We have investigated the role that the enzymatic activities of two complex components, the histone acetyltransferase activity of MOF and the ATPase activity of MLE, may have in the targeting and association of the complex with the X chromosome. Here we report that MLE and MOF activities are necessary for complexes to access the various X chromosome sites. The role that histone H4 acetylation plays in this process is supported by our observations that MOF overexpression leads to the ectopic association of the complex with autosomal sites.

Acetylation↗
PubMed2000

Selective blockade of IL-15 by soluble IL-15 receptor alpha-chain enhances cardiac allograft survival.

IL-15 is a T cell growth factor that shares many functional similarities with IL-2 and has recently been shown to be present in tissue and organ allografts, leading to speculation that IL-15 may contribute to graft rejection. Here, we report on the in vivo use of an IL-15 antagonist, a soluble fragment of the murine IL-15R alpha-chain, to investigate the contribution of IL-15 to the rejection of fully vascularized cardiac allografts in a mouse experimental model. Administration of soluble fragment of the murine IL-15R alpha-chain (sIL-15Ralpha) to CBA/Ca (H-2k) recipients for 10 days completely prevented rejection of minor histocompatibility complex-mismatched B10.BR (H-2k) heart grafts (median survival time (MST) of >100 days vs MST of 10 days for control recipients) and led to a state of donor-specific immunologic tolerance. Treatment of CBA/Ca recipients with sIL-15Ralpha alone had only a modest effect on the survival of fully MHC-mismatched BALB/c (H-2d) heart grafts. However, administration of sIL-15Ralpha together with a single dose of a nondepleting anti-CD4 mAb (YTS 177.9) delayed mononuclear cell infiltration of the grafts and markedly prolonged graft survival (MST of 60 days vs MST of 20 days for treatment with anti-CD4 alone). Prolonged graft survival was accompanied in vitro by reduced proliferation and IFN-gamma production by spleen cells, whereas CTL and alloantibody levels were similar to those in animals given anti-CD4 mAb alone. These findings demonstrate that IL-15 plays an important role in the rejection of a vascularized organ allograft and that antagonists to IL-15 may be of therapeutic value in preventing allograft rejection.

Animals↗
PubMed2000

Human immunodeficiency virus type-1 reverse transcription can be inhibited in vitro by oligonucleotides that target both natural and synthetic tRNA primers.

Reverse transcription of human immunodeficiency virus type-1 is primed by cellular tRNA(Lys3), which is selectively packaged into viral particles where it is bound at its 3' terminus to a complementary sequence of viral RNA termed the primer binding site (PBS). Since cellular tRNA(Lys3) is highly conserved, it might conceivably serve as a good target for novel antagonists to block reverse transcriptase (RT) activity. In this study, we have examined a number of antisense oligodeoxyribonucleotides (ODNs) that are complementary to different parts of the tRNA primer and, therefore, may interfere with the initiation of RT-mediated DNA synthesis. We found that the stability of complexes between synthetic tRNA(Lys3 )and ODNs was significantly increased when binding occurred via sequences involved in tertiary interactions of the tRNA. In particular, ODNs with complementarity to both the variable and TPsiC stem-loop of tRNA(Lys3 )bound with high affinity to both free tRNA(Lys3 )as well as to the binary tRNA(Lys3)/RNA complex. As a result, the initiation of DNA synthesis was severely compromised under these conditions. Moreover, RT-associated RNase H activity recognized the tRNA within this ternary tRNA(Lys3)/RNA/ODN complex as an RNA template and initiated its degradation. Both this RNase H degradation of tRNA(Lys3 )as well as the altered structure of the tRNA/RNA complex, due to the binding of the ODN, contributed to the inhibition of synthesis of viral DNA. The initiation of RT activity was almost completely blocked when using ODNs that interfered with intermolecular tRNA/RNA interactions that involved both the PBS and sequences outside the PBS. Similar findings were obtained with natural preparation of tRNA(Lys3).

Base Sequence↗
PubMed2000

Perillyl alcohol inhibits TCR-mediated [Ca(2+)](i) signaling, alters cell shape and motility, and induces apoptosis in T lymphocytes.

Perillyl alcohol (POH) inhibits isoprenylation and has shown anticancer and chemopreventive properties in rodent models. The mechanism that underlies the anticancer activity of POH and other isoprenylation inhibitors is unknown but has been postulated to involve decreased levels of isoprenylated Ras and Ras-related proteins. Previously we demonstrated that POH effectively inhibits human T cell proliferation in vitro and can prevent acute and chronic rejection in a rat cardiac transplant model. In this report, we investigate the effects of POH on T lymphocytes at the single-cell level. POH disrupts the polarized shape and motility of antigen-specific murine 1E5 T cells. Using an optical trap to position anti-CD3-coated beads in contact with 1E5 T cells, we demonstrate that POH inhibits their TCR-mediated calcium response. Furthermore, we show that POH preferentially induces apoptosis in PHA-activated human T cells as well as in 1E5 T cells.

Adult↗
PubMed2000

White matter abnormalities in mobility-impaired older persons.

OBJECTIVE: To investigate the relationship between white matter abnormalities and impairment of gait and balance in older persons. METHODS: Quantitative MRI was used to evaluate the brain tissue compartments of 28 older individuals separated into normal and impaired groups on the basis of mobility performance testing using the Short Physical Performance Battery. In addition, individuals were tested on six indices of gait and balance. For imaging data, segmentation of intracranial volume into four tissue classes was performed using template-driven segmentation, in which signal-intensity-based statistical tissue classification is refined using a digital brain atlas as anatomic template. RESULTS: Both decreased white matter volume, which was age-related, and increased white matter signal abnormalities, which were not age-related, were observed in the mobility-impaired group compared with the control subjects. The average volume of white matter signal abnormalities for impaired individuals was nearly double that of control subjects. CONCLUSIONS: This cross-sectional study suggests that decreased white matter volume is age-related, whereas increased white matter signal abnormalities are most likely to occur as a result of disease. Both of these changes are independently associated with impaired mobility in older persons and therefore likely to be additive factors of motor disability.

Aged↗
PubMed2000

Study on DNA strand breaks induced by sodium nitroprusside, a nitric oxide donor, in vivo and in vitro.

Nitric oxide (NO) as well as its donors has been shown to generate mutation and DNA damage in in vitro assays. The objective of this study was to identify that DNA single-strand breaks (SSBs) could be elicited by NO, not only in vitro but also in vivo. The alkaline single-cell gel electrophoresis (SCGE) was performed to examine the DNA damage in g12 cells and the cells isolated from the organs of mice exposed to sodium nitroprusside (SNP). A modified method, in which neither collagenase nor trypsin was necessary, was used to prepare the single-cell suspension isolated from organs of mice. Results showed that the exposure of g12 cells to 0.13-0.5 micromol/ml SNP with S9 for 1 h induced a concentration-dependent increase in DNA SSBs in g12 cells. The significant increase in DNA migration and comet frequency has appeared in the cells isolated from the spleen, thymus, and peritoneal macrophages of mice after injecting i.p. SNP in the dosage range of 0.67-6.0 mg/kg b.wt for 1 h. However, no obvious increase in DNA strand breaks was observed in the cells isolated from the liver, kidney, lung, brain and heart obtained from the same treated mice. These results suggested that DNA SSBs could be induced by NO in some cells both in vivo and in vitro. There were organ differences in sensitivity in the mice exposed to NO. Spleen, thymus, and macrophages might be the important targets of NO.

Akathisia, Drug-Induced↗
PubMed2000

Fullerene-sensitized

[reaction: see text] Fullerene catalyzes the cycloaddition of dimethyliminodiacetate to maleimides under photolysis to form 2,5-dimethoxycarbonylpyrrolidine derivatives.

Journal Article↗
PubMed2000

Activated macrophages direct apoptosis and suppress mitosis of mesangial cells.

During inflammation in the glomerulus, the complement of resident myofibroblast-like mesangial cells is regulated by mitosis and apoptosis, but the cellular mechanisms controlling the size of mesangial cell populations have remained obscure. Prompted by studies of development, we sought evidence that macrophages regulate mesangial cell number. Rat bone marrow-derived macrophages primed with IFN-gamma then further activated in coculture with LPS or TNF-alpha elicited a 10-fold induction of rat mesangial cell apoptosis and complete suppression of mitosis, effects inhibitable by the NO synthase inhibitors L-monomethyl arginine and L-N(6)-(1-iminoethyl) lysine dihydrochloride. Complete dependence upon macrophage-derived NO was observed in comparable experiments employing activated bone marrow macrophages from wild-type and NO synthase 2(-/-) mice. Nevertheless, when mesangial cells were primed with IFN-gamma plus TNF-alpha, increased induction by activated macrophages of mesangial apoptosis exhibited a NO-independent element. The use of gld/gld macrophages excluded a role for Fas ligand in this residual kill, despite increased expression of Fas and increased susceptibility to soluble Fas ligand exhibited by cytokine-primed mesangial cells. Finally, activated macrophages isolated from the glomeruli of rats with nephrotoxic nephritis also induced apoptosis and suppressed mitosis in mesangial cells by an L-monomethyl arginine-inhibitable mechanism. These data demonstrate that activated macrophages, via the release of NO and other mediators, regulate mesangial cell populations in vitro and may therefore control the mesangial cell complement at inflamed sites.

Animals↗
PubMed2000

Tandem Intermolecular - Intramolecular Carbolithiation: A Versatile Method for Synthesis of Cyclopentanes.

Polysubstituted cyclopentanes from readily available starting materials? A versatile anionic [3+2] approach is offered by the reaction of difunctional organolithium reagents 1 with alkenes 2 in a tandem intermolecular - intramolecular carbolithiation (see scheme). This convergent sequence is especially attractive as, not only are the precursors readily available, but the products provide valuable synthetic building blocks.

Journal Article↗
PubMed2000

Iridoids from Dunnia sinensis.

A plumieride type iridoid glucoside, dunnisinoside, and a non-glucosidic iridoid, dunnisinin, were isolated from the leaves of Dunnia sinensis. Their structures were established by 1D and 2D NMR and FABMS experiments.

Anti-Inflammatory Agents↗
PubMed2000

Application of sample pre-oxidation of arsenite in human urine prior to speciation via on-line photo-oxidation with membrane hydride generation and ICP-MS detection.

A pre-oxidation procedure which converts arsenite [As(III)] into arsenate [As(v)] was investigated in urinary arsenic speciation prior to on-line photo-oxidation hydride generation with ICP-MS detection. This sample pre-oxidation method eliminates As(III) and As(v) preservation concerns and simplifies the chromatographic separation. Four oxidants, Cl2, MnO2, H2O2 and I3-, were investigated. Chlorine (ClO-aq) and MnO2 selectively converted As(III) into As(v) in pure water samples, but the conversion was inefficient in the complex urine matrix. Oxidation of As(III) by H2O2 was least affected by the urine matrix, but the removal of excess H2O2 at pH 10 proved difficult. The most appropriate oxidant for the selective conversion of As(III) into As(v) with minimal interference from the urine matrix is I3- at pH 7. Unlike H2O2, excess oxidant can be easily removed by the addition of S2O3(2-). The I3-(-)S2O3(2-) treatment on a fortified sample of reconstituted NIST SRM 2670 freeze dried urine indicated that arsenobetaine (AsB), dimethlyarsinic acid (DMA), monomethylarsonic acid (MMA) and As(v) were not chemically degraded with recoveries ranging from 95 to 102% for all arsenicals. Sample clean-up involved pH adjustment prior to C18 filtration in order to achieve efficient As(III) conversion and quantitative recoveries of AsB and DMA. The concentrations determined in NIST SRM 2670 freeze dried urine were AsB 17.2 +/- 0.5, DMA 56 +/- 4 and MMA 10.3 +/- 0.3 with a combined total of 83 +/- 5 micrograms L-1 (+/- 2 sigma).

Arsenites↗
PubMed2000

Nonlinear optical studies of liquid crystal alignment on a rubbed polyvinyl alcohol surface

Sum-frequency vibrational spectroscopy and second-harmonic generation have been used to measure the orientational distributions of the polymer chains and adsorbed 8CB liquid crystal molecules on a rubbed polyvinyl alcohol surface. Results show that the polymer chains at the surface appear to be well aligned by rubbing, and the adsorbed liquid crystal molecules are aligned, in turn, by the surface polymer chains. Strong correlation exists between the orientational distributions of the polymer chains and the liquid crystal molecules, indicating that the surface-induced bulk alignment of a liquid crystal film by rubbed polymer surfaces is via an orientational epitaxylike mechanism.

Journal Article↗
PubMed2000

The origin and development of the upper lateral incisor and premaxilla in normal and cleft lip/palate monkeys induced with cyclophosphamide.

OBJECTIVE: Cleft lip/palate (CLP) is a common human congenital defect in which the maxillary lateral incisors are often absent, malformed, and malpositioned. The present study was designed to examine the origin of the upper primary lateral incisor relative to the medial nasal process (MNP) and maxillary process (MP) fusion area and to the premaxillary/maxillary (incisive) suture in monkeys. METHOD: Scanning electron microscopy, histology, skeletal staining, and drying techniques were used to study facial development in embryo and fetal monkey specimens. A teratogenic dose of cyclophosphamide was administered to pregnant monkeys prior to fusion of the MNP and MP and fetuses were examined for CLP. RESULTS: Formation of the anterior maxilla involved fusion of the MNP and MP at stages 14-18. At stages 18-20, the palatal portion of the MNP had formed the medial and lateral incisive mounds. By stage 22, the upper primary lateral incisor has formed within the MP, lateral to the MNP/MP fusion area and to the ossifying premaxilla. Ossification of the premaxilla begins in the MNP and subsequently spreads laterally across the MNP/MP fusion area into the MP. Accordingly, the lateral incisor undergoes a complex positional shift (mainly medial) relative to the incisive suture both prenatally and postnatally and is finally located medial to the suture. Examination of the cyclophosphamide-induced CLP fetuses showed that the lateral incisor is located lateral to the alveolar cleft and does not shift medial to the incisive suture. CONCLUSION: Understanding the origin of the lateral incisor (the tooth closest to the cleft) and the shift after its formation provides clues to high incidence of malformations and ectopia of this incisor in cleft patients.

Alveolar Process↗
PubMed2000

[Association between hypertensive cerebrovascular stroke and renin-angiotensin system gene polymorphism from Chinese cohort in Shanghai].

OBJECTIVE: To evaluate the association between hypertensive cerebrovascular stroke and renin-angiotensin system gene polymorphism from Chinese cohort. METHODS: The polymorphisms of angiotensinogen(AGT) and angiotensin-converting enzyme(ACE) from 257 cases of simple essential hypertension(EH) and 218 cases of hypertensive stroke(131 hemorrhagic cases and 87 ischemic cases were detected by PCR-RFLP. RESULTS: The frequencies of DD genotype and D allele of ACE gene in ischemic stroke were significantly higher than those in hemorrhagic stroke and EH, and the odds ratios(OR) of DD/II genotype were 3.25(2.20-4.79) and 2.87(2.03-4.06), while the OR of D/I allele were 1.83(1.38-2.43) and 1.69(1.27-2.24) respectively. Otherwise, there was no difference in frequency distribution of Met235Thr mutation polymorphism and DD+TT/non DD non TT combined among the three groups. CONCLUSION: The I/D polymorphism of ACE gene may be one of the risk factors and susceptible genetic markers for ischemic stroke with essential hypertension in Chinese.

Angiotensinogen↗
PubMed2000

[Retrovirus vector expresses luciferase and TPO gene under the control of doxycycline in NIH3T3 cells].

OBJECTIVE: To use the retrovirus vector Tet-On regulation system to control the expression of TPO and luciferase gene by doxycycline (Dox). METHODS: Packing the recombinant Tet-On retrovirus, and infecting it to NIH3T3 cells to establish recombined Tet-On retrovirus cell lines, RevTet-On3T3. To construct the pRevTRETPO, the new cell line was transferred to PT67 cell to package the recombinant retrovirus which contained both the TRE and TPO. This virus was RevTet-On3T3 used to establish the two inserting recombinant retrovirus cell strain RevTet-On3T3TPO. Doxycycline was used to control the expression of TPO in RevTet-On3T3. RESULTS: When Dox (5 mg/L) was added to the RevTet-On3T3 cells, a higher activity of luciferase was seen (mean, 5.9 x 10(4) RLU.S) compared with the mean activity (2.6 x 10(3) RLU.S) in the absence of Dox. When Dox was added to the RevTet-On3T3TPO cells, cell populations had high TPO expression (mean, 12.8 ng/ml) in 5 mg/L of Dox (On state), and a low TPO expression (mean, 0.56 ng/ml) in the absence of Dox (Off state). CONCLUSION: The RevTet-On gene expression system could modulate the expression of multiple genes by tetracycline and its derivatives, providing a useful tool for gene therapy.

3T3 Cells↗
PubMed2000

[The value of serum alpha-L-fucosidase activity in the diagnosis of primary liver cancer].

OBJECTIVE: To analyse the value of serum alpha-L-fucosidase (AFU) in the diagnosis of primary liver cancer (PLC). METHODS: Serum AFU was studied in 141 patients with PLC, 17 patients with secondary liver cancer, 16 patients with cirrhosis, and 30 controls. Rank correlation analysis was used to assess the relation between value of AFU activity and TNM staging. The results were compared to those of serum AFP determination. RESULTS: AFU was increased in 108 of 141 (76.6%) patients. The positive rate was statistically different from that in patients with secondary liver cancer, cirrhosis, and that in normal individual. The AFU level was correlated with TNM stage. In 25 PLC patients with AFU > 500 nmol.L-1.S-1, the average survival time was only 71 days. In 36 PLC patients who had received effective treatment, the serum AFU decreased to a significantly lower level than that examined before treatment. The positive rate of AFP in PLC patients was 64.5%. It rose to 86.2% if both parameters were used. CONCLUSION: AFU is a useful marker of PLC for diagnosis and posttreatment monitoring.

Adult↗