Biomedical subjects

J Xie

Publications and source records attributed to J Xie.

At least 109 records · Page 6Linked to original sources

PubMed2000

[A strain of influenza A H9N2 virus repeatedly isolated from human population in China].

OBJECTIVE: To understand the subtype of surface proteins (hemagglutinin and neuraminidase) and antigenic character of the isolate of influenza virus, as well as to know its origin. METHODS: The virus isolation was performed on MDCK cells. The identification and antigenic analysis of the isolate were carried out with HI and NI tests. The serum antibody in population against the isolate was detected with HI and neutralization assays. The individual investigation of the patient from whom the H9N2 virus was isolated was followed. RESULTS: The isolate was H9N2 subtype of influenza A virus. It was G9 like strain. Its antigenicity was different from that of H9N2 viruses which were previously found in humans, chickens and pigeons. The HI and neutralization titers to H9N2 virus in convalescent serum of the patient reached 1:400 and > or =1: 640, respectively. The HI antibody titer 1:25 to H9N2 virus was also detected in the serum of patient's mother. CONCLUSIONS: The isolate is H9N2 subtype of influenza A virus and belongs to G9 like strain. The antigenic character of the isolate was different from that of H9N2 viruses found previously in humans, chickens and pigeons. The greatest possibility was that her mother had contacted with birds, especially chickens carrying H9N2 virus, then transmitted to her or she breathed in the air borne with H9N2 virus particles directly.

Adult↗

PubMed2000

[Life table analysis of Tsuga longibracteata population].

Tsuga longibracteata is a rare and endangered tree species in China. Based on the life table of population and the theory of survival analysis, the authors worked out the life table of Tsuga longibracteata population drew the curves of mortality density function, hazard rate function and survival, and analyzed the population dynamics. The results show that the population had two peaks of mortality, and the survival curve of the population trended to the type of Deevey II.

China↗

PubMed2000

Recombinant bovine basic fibroblast growth factor accelerates wound healing in patients with burns, donor sites and chronic dermal ulcers.

OBJECTIVE: To evaluate the effect of recombinant bovine basic fibroblast growth factor (rbFGF) on accelerating healing of burn wounds, donor sites and chronic dermal ulcers in multicenters. METHODS: One thousand and twenty-four patients with burns, donor sites and chronic dermal ulcers were recruited for this prospective and multicenter clinical trial and another 641 patients with the similar wounds were used as controls. All patients were divided into three groups: burn group, donor site group, and chronic dermal ulcer group. In the burn group, 654 patients with superficial second-degree burns(superficial II degree) or deep second-degree burns(deep II degree) were treated topically with either recombinant bovine basic fibroblast growth factor (rbFGF plus vehicle, rbFGF 150 AU/cm2/day, 330 patients) or placebo (vehicle without rbFGF, 324 patients). In the donor site group, 509 patients were treated with rbFGF and 317 patients with placebo in a similar way as described elsewhere. In the chronic dermal ulcer group, 185 patients were treated with rbFGF and the controls were themselves. Photography, histological evaluation and clinical examination were used to evaluate the results of wound healing. RESULTS: All of superficial second-degree burns, deep second-degree burns and the donor sites treated with recombinant bovine basic fibroblast growth factor had an accelerated rate of granulation tissue formation and epidermal regeneration as compared with that in the controls. Superficial second-degree burns and deep second-degree burns treated with recombinant bovine basic fibroblast growth factor healed in 9.89 +/- 2.45 and 17.04 +/- 4.56 days, respectively, whereas the average healing time in those receiving placebo was 12.35 +/- 2.74 and 21.21 +/- 4.88 days. The donor sites treated with rbFGF or placebo healed in 10.68 +/- 4.55 and 14.74 +/- 6.46 days, respectively. All chronic dermal ulcers except 12 patients treated with rbFGF healed within 6 weeks. Histological evaluation of punch-biopsy specimens from the burn wounds, donor sites and chronic dermal ulcers seven days after treatment supported the impression of accelerated wound healing after rbFGF treatment. CONCLUSIONS: rbFGF is effective in shortening the wound healing time and improving the wound healing quality. Accelerating wound healing is of clinical benefit in reducing the length of hospitalization, costs and emotional burden of the patient.

Adolescent↗

PubMed2000

[Craniovertebral decompression and posterior fossa reconstruction treatment of Chiari syringomyelia complex].

OBJECTIVE: To study the results of Chiari malformation/syringomyelia (CM-SM) complex treated by craniovertebral decompression and posterior fossa reconstruction (PFR). METHODS: 37 patients of CM-SM complex were treated surgically from 1994 to 1999. All patients underwent craniovertebral decompression and posterior fossa reconstruction. The procedure consisted of suboccipital craniectomy and laminectomy of C1 (when necessary C2), exploration and plugging of the obex, and resection of arachnoid adherence. A wide dural graft was used to reconstruct the cisterna magna artificially. Syrinx shunt was not performed. RESULTS: Follow-up for 0.5 to 4.5 years showed that 31 patients (83.8%) had their symptoms improved, 5 (13.5%) stabilized, but 1 (2.7%) deteriorated. Magnetic resonance was used to evaluate the morphological results. The shrinkage of the syrinx, upward migration of the hindbrain, the formation of an artificial cisterna magna were observed. CONCLUSIONS: Craniovertebral decompression and posterior fossa reconstruction in restoring the craniovertebral junction are recommended in the treatment of CM-SM complex.

Adolescent↗

PubMed2000

[Effect of mouse p53 minigene on lung cancer cells with different 172 structures regulated by tetracycline].

OBJECTIVE: To investigate the effect of mouse 172 wild-type p53 (Arg), pseudo-wild-mutant-type p53 (Arg-->Leu) and mutant-type p53 (Arg-->His) induced by absence of tetracycline on the growth of PG cell line. METHODS: Three variant types of p53 minigene were sub-cloned by gene recombination into an expression vector which was controlled by tetracycline. Through LipofectAMINE, the vectors were transfected into p53 defective PG (248CGG-->CTT) cells, and the transfectants were screened in the selecting medium containing puromycin. Tumor suppressing effects were studied by MTT absorption, flow cytometry and Western blotting. RESULTS: Wild-type p53 and pseudo-wild-mutant-type p53 could lead cells to decrease their growth rates, arrest cell cycle and transactivation of p21(WAF1). Mutant-type p53 was defective in tumor suppression. CONCLUSION: Wild-type p53 and pseudo-wild-type p53 may inhibit cell growth and induce cell cycle arrest. Some p53 variants such as 172 Arg-->Leu can still retain the tumor suppression function of the wild-type.

Amino Acid Substitution↗

PubMed2000

[Effects of Asiaticoside on hypertrophic scars in a nude mice model].

OBJECTIVE: To study the effect of Asiaticoside on the fibroblast collagen biosynthesis in vitro culture and on the hypertrophic scar in a nude mice model, and its mechanism. METHODS: Light microscope (LM) and electron microscope (EM) were employed to study the morphological changes in fibroblast before and after the application of Asiaticoside. The fibroblast collagen synthesis was assayed by (3)H-proline incorporation. A nude mice model with hypertrophic scar was established for observing the effect of Asiaticoside given by local injection. RESULTS: It was found that Asiaticoside could significantly affect the ultrastructure of fibroblast and inhibit its collagen synthesis in vitro culture (P < 0.01) in a manner of dose-effect relationship. Local injection of Asiaticoside into the nude mouse body could inhibit the proliferation of scar without any toxic effect. CONCLUSION: The possible mechanism of the effect of Asiaticoside on hypertrophic scars is related to its inhibitory action on the fibroblast proliferation and collagen synthesis.

Animals↗

PubMed2000

[Linkage analysis of the G6PD gene mutations and its Nla III polymorphic site].

OBJECTIVE: To investigate the molecular and anthropologic features of glucose-6-phosphate dehydrogenase (G6PD) deficiency and the linkage between the Nla III polymorphic site within G6PD gene and three common Chinese G6PD mutations. METHODS: By using denatured gradient gel electrophoresis (DGGE) and allele specific oligonucleotide (ASO) probe dot blot hybridization, Nla III polymorphic site at minus sign13 bp upstream exon 12 within G6PD gene were screened in 54 males with normal G6PD activity and 66 G6PD deficient males. RESULTS: Thirty-two cases with cDNA1376 (G-->T), 21 with cDNA1388 (G-->A) and 13 with cDNA95 (A-->G) were detected in the 66 G6PD deficient males. Among 54 normal controls, T at -13 bp upstream exon 12 within G6PD gene were detected in 11 cases (20.4%, without Nla III polymorphic sites) while C in 43 cases (79.6%, with Nla III polymorphic sites). All 66 G6PD deficient males were linked with C at -13 bp upstream exon 12 (with Nla III polymorphic sites). CONCLUSION: The G6PD mutations cDNA1376 (G-->T), cDNA1388 (G-->A) and cDNA95 (A-->G) were linked with Nla III polymorphism. This feature will play a role in studying the complicated manifestations and anthropology of G6PD deficiency.

Genetic Linkage↗

PubMed2000

[Separation and enrichment of fetal nucleated red blood cells from maternal blood for non-invasive prenatal gene diagnosis].

OBJECTIVE: In order to develop a non-invasive technique for prenatal gene diagnosis. METHODS: Peripheral blood mononuclear cells (MNCs) were separated by single density gradient Histopaque 1.077 from 25 pregnant women with gestations between 8 - 36 weeks. The fetal nucleated red blood cells (NRBCs) were enriched from the MNCs by positive selection using Dynabeads M-450 CD(71) or negative selection using Dynabeads M-450 CD(45). The enriched NRBCs were identified by anti-gamma-biotin or anti-zeta-biotin antibodies. Globin gene of NRBCs from fetuses with risk of beta-thalassemia major were amplified with nested PCR followed by reverse dot blot hybridization for gene diagnosis. RESULTS: NRBCs stained by anti-gamma-biotin or anti-zeta-biotin antibodies could be found in the peripheral blood samples of the 25 pregnant women. Three out of 5 fetuses with risk of beta-thalassemia major were successfully diagnosed using these NRBCs. CONCLUSION: Fetal NRBCs in maternal circulation can be isolated and enriched by single gradient density Histopaque 1.077 followed by magnetic activated cell sorting. Nested PCR can amplify DNA for gene diagnosis from no less than 20 NRBCs.

Biotin↗

PubMed2000

[Study on multi-element determination in drinking water by ICP-OES and ICP-MS].

A new method was developed for the determination of twenty-three elements in water samples by ICP-OES and ICP-MS. The detection limits, standard deviations and linear calibration ranges were measured. The sensitivity of the method was excellent and the determination was very fast for various elements including Ca, Mg, Fe, Mn, B, Cr, Si, Zn, Be, Al, V, Co, Ni, Cu, As, Se, Mo, Ag, Cd, Sb, Ba, Tl and Pb. Preconcentration and separation procedures were not required and hence the potential cross contamination was minimized. Recoveries of the standards spiked to natural samples were at the range of 94.5%-116.2%. Besides, the analytical values of standard reference materials obtained by the proposed method were conformed well with the certified values. The accuracy of results was further validated by comparing with the data obtained by using AAS and AFS. The proposed method was applied in the quality study of Shenzhen drinking water. A precise and accurate background data of various trace elements content of the city was obtained.

Calcium↗

PubMed1999

Sum1 and Hst1 repress middle sporulation-specific gene expression during mitosis in Saccharomyces cerevisiae.

Meiotic development in yeast is characterized by the sequential induction of temporally distinct classes of genes. Genes that are induced at the middle stages of the pathway share a promoter element, termed the middle sporulation element (MSE), which interacts with the Ndt80 transcriptional activator. We have found that a subclass of MSEs are strong repressor sites during mitosis. SUM1 and HST1, genes previously associated with transcriptional silencing, are required for MSE-mediated repression. Sum1 binds specifically in vitro to MSEs that function as strong repressor sites in vivo. Repression by Sum1 is gene specific and does not extend to neighboring genes. These results suggest that mechanisms used to silence large regions of chromatin may also be used to regulate the expression of specific genes during development. NDT80 is regulated during mitosis by both the Sum1 and Ume6 repressors. These results suggest that progression through sporulation may be controlled by the regulated competition between the Sum1 repressor and Ndt80 activator at key MSEs.

Binding Sites↗

PubMed1999

A single conductance pore for chloride ions formed by two cystic fibrosis transmembrane conductance regulator molecules.

The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-dependent protein kinase (PKA)- and ATP-regulated chloride channel, whose gating process involves intra- or intermolecular interactions among the cytosolic domains of the CFTR protein. Tandem linkage of two CFTR molecules produces a functional chloride channel with properties that are similar to those of the native CFTR channel, including trafficking to the plasma membrane, ATP- and PKA-dependent gating, and a unitary conductance of 8 picosiemens (pS). A heterodimer, consisting of a wild type and a mutant CFTR, also forms an 8-pS chloride channel with mixed gating properties of the wild type and mutant CFTR channels. The data suggest that two CFTR molecules interact together to form a single conductance pore for chloride ions.

Adenosine Triphosphate↗

PubMed1999

A frequent activated smoothened mutation in sporadic basal cell carcinomas.

Basal-cell carcinomas (BCCs) are the most common cancer in Caucasians. It has been reported that the patched gene is inactivated in 30-40% sporadic BCCs and 20% sporadic medulloblastomas via loss of heterozygosity and nonsense mutations. Recently, two activating smoothened mutations have been found in the sporadic basal cell carcinomas. One, at base pair 1604 (G-to-T transversion) of exon 9, changes codon 535 from tryptophan to leucine, and the other, at base pair 1685 (G-to-A transition) of exon 10, changes codon 562 from arginine to glutamine (Xie et al., 1998). In our study, 1604G-->T was found in 20 out of 97 (20.6%) sporadic BCCs. The high prevalence indicates that 1604G is the mutation hot spot in our tumor samples. This mutation was detected in all three histological subtypes of BCCs, suggesting that smoothened mutation is an early event during the development of the tumor. Our finding of a high smoothened mutation rate, together with high frequent patched gene mutations reported recently, indicates that activation of the hedgehog signal transduction pathway is the most common and early event in the development of sporadic BCCs. Additionally, to determine whether smoothened, like patched, is also involved in the carcinogenesis of medulloblastomas, we screened medulloblastoma samples for these two mutations by restriction analysis. We have found the 1604G-->T mutation in 1 out of 21 medulloblastomas. This result confirmed smoothened gene involvement in the carcinogenesis of medulloblastoma.

Basal Cell Carcinoma↗

PubMed1999

Constitutive lysosomal targeting and degradation of bovine endothelin-converting enzyme-1a mediated by novel signals in its alternatively spliced cytoplasmic tail.

Endothelin-converting enzyme-1 (ECE-1) is a type II membrane protein that catalyzes the proteolytic activation of big endothelin-1 to endothelin-1 (ET-1). The subcellular distribution of ECE-1, and hence the exact site of physiological activation of big ET-1, remains controversial. Here, we demonstrate with several complementary methods that the two alternatively spliced bovine ECE-1 isoforms, ECE-1a and ECE-1b, differing only in the first 30 amino acids of their N-terminal cytoplasmic tails, exhibit strikingly distinct intracellular sorting patterns. Bovine ECE-1a, which is responsible for the intracellular cleavage of big ET-1 in endothelial cells, is constitutively recruited into the lysosome, where it is rapidly degraded. In contrast, bovine ECE-1b, the isoform found in cultured smooth muscle cells, is transported to the plasma membrane by a default pathway and functions as an ectoenzyme. Mutational analyses reveal that the N-terminal tip of the cytoplasmic domain of bovine ECE-1a contains novel proline-containing signals that mediate constitutive lysosomal targeting. Analyses of chimeric ECE-1/transferrin receptors demonstrate that the cytoplasmic tail of bovine ECE-1a is sufficient for the lysosomal delivery and rapid degradation. Our results suggest that the distinct intracellular targeting of bovine ECE-1 isoforms may provide new insights into functional aspect of the endothelin system and that the cell permeability of ECE inhibitor compounds should be carefully considered during their pharmacological development.

Alternative Splicing↗

PubMed1999

Electron spin resonance studies on photosensitized formation of hydroxyl radical by C-phycocyanin from Spirulina platensis.

Visible light (>470 nm) irradiation of an oxygen-saturated solution of C-phycocyanin (C-PC) in the presence of the spin trap 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) gave an ESR spectrum characteristic of the DMPO-hydroxyl radical spin adduct DMPO-OH. The signal intensities of DMPO-OH adduct were enhanced by superoxide dismutase (SOD) and partly inhibited by catalase. It was partly responsible for the production of DMPO-OH that superoxide anion radical (O.-2) dismutated to generate hydrogen peroxide (H2O2) which decomposed ultimately to generate the highly reactive .OH. In addition, it can be concluded that singlet oxygen (1O2) was an important intermediate according to the strong inhibitory action of 1,4-diazabicyclo[2.2.2]octane (DABCO) and histidine on DMPO-OH formation. The experimental results suggest that photodynamic action of C-PC proceed via both type I and type II mechanisms. Furthermore, the decay kinetics of DMPO-OH adduct, the effects of DMPO and C-PC concentrations as well as irradiation time on DMPO-OH adduct formation were also discussed. Concentration of C-PC should be an important factor to influence the ESR signal intensities of DMPO-OH. Therefore, it may be concluded that reasonably lower concentration of C-PC might prolong the duration of photosensitized formation of .OH and might strengthen the photodynamic action.

Cyclic N-Oxides↗

PubMed1999

Transformation of modified brushite to hydroxyapatite in aqueous solution: effects of potassium substitution.

Brushite (dicalcium phosphate dihydrate, DCPD, CaHPO4 x 2H2O) was deposited electrolytically from calcium dihydrogen phosphate solution with and without potassium chloride (KCl) as a supporting electrolyte. The kinetics of brushite transformation to hydroxyapatite (HA, Ca5(PO4)3OH) in the presence of calcium and protein free, aqueous body fluid (Hank's balanced salt solution, HBSS) was investigated. We present evidence that the deposition of brushite in a KCl-supported electrochemical bath yields a modified brushite where some of the calcium is substituted by potassium. Transformation of both normal (i.e. potassium free) and modified brushite to hydroxyapatite upon exposure to calcium and protein-free aqueous fluid (HBSS) was followed by reflectance Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques. Changes in the morphology of the coatings were studied using scanning electron microscopy (SEM). Results indicate that modified brushite undergoes faster transformation to hydroxyapatite in HBSS in comparison to normal brushite. Our results show that the presence of potassium ions in the brushite not only favors the formation of different intermediate phases but also alters transformation rates to HA.

Calcium Phosphates↗

PubMed1999

Ethanol metabolism is not required for inhibition of LPS-stimulated transcription of inducible nitric oxide synthase.

We examined the effect of inhibition of ethanol metabolism on ethanol-mediated suppression of Escherichia coli endotoxin (LPS-induced upregulation of transcription and release of inducible nitric oxide synthase (iNOS) and tumor necrosis factor alpha (TNFalpha) from rat alveolar macrophages (AM) in vivo. Ethanol (3.45 and 5.5 g/kg/IP) and t-butanol (3.7 g/kg, IP), given 30 min before intratracheal administration of LPS (1.0 mg/kg), inhibited the upregulation of iNOS mRNA and protein, determined by competitor equalized RT-PCR and Western immunoblot, respectively, but not TNFalpha mRNA in AM obtained 2 h after LPS administration by bronchoalveolar lavage (BAL). However, ethanol and t-butanol inhibited LPS-stimulated nitrate and nitrite (RNI) and TNFalpha protein in BAL fluid. Pretreatment of rats with 4-methylpyrazole (100 mg/kg, IP) 2 h before, or disulfiram 30 min before, administration of ethanol (3.45 g/kg, IP) failed to attenuate the inhibitory effect on iNOS mRNA or protein. t-Butyl hydroperoxide (100 mg/kg, IP) given to rats 30 min before administration of LPS enhanced LPS-mediated upregulation of iNOS mRNA and TNFalpha protein in AM and BAL fluid. The inhibitory effect of ethanol on iNOS mRNA was not mediated by an interaction with elevated levels of circulating corticosterone because pretreatment of rats with RU-38486 (100 mg/kg, IM), which inhibited prednisolone (50 mg/kg, IM), induced suppression of LPS-stimulated iNOS mRNA, and failed to attenuate ethanol-mediated inhibition of LPS-stimulated iNOS mRNA in AM. We conclude that metabolism of ethanol to acetaldehyde via alcohol dehydrogenase is not required for ethanol-mediated suppression of LPS-induced iNOS transcription and TNFalpha synthesis/release in AM. Moreover, an interaction of ethanol or acetaldehyde with circulating corticosterone is not involved in ethanol-mediated attenuation of LPS-stimulated iNOS mRNA or protein or TNFalpha protein in the lung. Speculatively, because oxidation of t-butanol to t-butylhydroperoxide results in activation, rather than inhibition, of iNOS and TNF-alpha, the reported ethanol-mediated enhancement of iNOS mRNA may result from the action of the hydroxyethyl radical.

Alcohol Dehydrogenase↗

PubMed1999

Microfabrication techniques using focused ion beams and emergent applications.

The application of focused ion beam (FIB) machining in several technologies aimed at microstructure fabrication is presented. These emergent applications include the production of micromilling tools for machining of metals and the production of microsurgical tools. An example of the use of microsurgical manipulators in a circulatory system measurement is presented. The steps needed to transform the laboratory fabrication of these tools and manipulators into a routine FIB production process are discussed. The ion milling of three-dimensional cavities by the exact solution of a mathematical model of the FIB deflection is demonstrated. A good agreement between the model calculation and the ion beam control has been obtained for parabolic and cosine cross-section features with planes of symmetry.

Animals↗

PubMed1999

Inhibitory effect of green and black tea on tumor growth.

The administration of green tea, black tea, or (-)-epigallocatechin gallate inhibited the growth of established nonmalignant and malignant tumors in tumor-bearing mice. In experiments with black tea, we found that its oral administration inhibited DNA synthesis and enhanced apoptosis in both nonmalignant and malignant tumors in tumor-bearing mice.

Animals↗