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Biomedical subjects

Y Qi

Publications and source records attributed to Y Qi.

At least 55 records · Page 3Linked to original sources
PubMed2001

Control of oligodendrocyte differentiation by the Nkx2.2 homeodomain transcription factor.

Oligodendrocytes are derived from glial precursors that arise from the ventral neural tube early in development. In the developing chicken CNS, oligodendrocyte progenitors selectively express Nkx2.2 homeodomain transcription factor, raising the possibility that Nkx2.2 may directly regulate oligogliogenesis. In this study, we have examined Nkx2.2 expression in rodent glial precursors and studied the effect of a loss of Nkx2.2 on oligodendrocyte and astrocyte differentiation. We show that Nkx2.2 is also expressed in mammalian oligodendrocyte progenitors and that the differentiation of MBP-positive and PLP-DM20-positive oligodendrocytes is dramatically retarded in Nkx2.2-null mutants along the entire rostrocaudal axis. In contrast, no effect is seen on astrocytic differentiation. Interestingly, absence of Nkx2.2 expression leads to a ventral expansion of the Olig1/Olig2 expression in neuroepithelial cells into the Nkx2.2 domain and a consequent increase in the production of Olig1/Olig2-positive and platelet-derived growth factor receptor alpha-positive oligodendrocyte progenitors. These results strongly suggest that Nkx2.2 regulates the differentiation and/or maturation, but not the initial specification, of oligodendrocyte progenitors. Consistent with this suggestion, overproduction of Nkx2.2 protein in fibroblast cells can induce gene expression from the proteolipid protein promoter.

3T3 Cells↗
PubMed2001

[Establishment of platelet-mediated transmitochondrial cell model].

OBJECTIVE: To establish a transmitochondrial cell model for further researches on molecular genetics of mitochondrial related disease. METHODS: The fusion process was conducted between mitochondrial DNA-lacking rho degrees cell (a gift from NIH) and platelet using polyethylene glycol as fusion promoting reagent. The fusion cells were confirmed by PCR and electronic microscopic cytochemistry. The mitochondrial morphology and function of 3 families of Rett syndrome were investigated. RESULTS: The platelet-mediated transmitochondrial cell model was constructed successfully. The frequency of transformation ranged from 0.5 to 1.6 clones in 10(4) recipient cells. The mitochondrial vacuolation was occasionally observed in 2 cases of Rett syndrome. CONCLUSION: Transmitochondrial cell model can be applied to assessment of the mitochondrial morphology and function of fusion cells and is found to be of great use in evaluating the gene expression of mitochondrial genome at different levels.

Blood Platelets↗
PubMed2001

[Bioaccumulation mechanism of red tide alga Prorocentrum micans for heavy metal ions].

Pollution of heavy metal from industrial wastewater is a worldwide environmental problem. Biosorption is an effective technology for the treatment of low concentration industrial wastewater. The purpose of this study was to evaluate the heavy metal uptake capacities of the biomass of marine red tide Prorocentrum micans. All red tide biomass used in this study were obtained from cultivation in our lab. Batch experimental results showed that living and non-living biomass of P. micans killed by CH2O were similar setting property for Cu2+, Pb2+, Ni2+, Zn2+, Ag+ and Cd2+. This study indicated that biomass of P. micans has a high capacities for above six heavy metal and the kinetics under the conditions studied were relatively fast. About 90% of the biosorption occurred within 10 min and an equilibrium was reached in 30 min. The Biosorption capacities for heavy metal ions were strongly dependent on pH of the solution, and higher capacities were obtained at pH around 5 and higher. Bonding and FIR of P. micans polysaccharide obtained by the hot water method for Cu2+, Pb2+, Ni2+, Zn2+, Ag+ and Cd2+ was also studied. The study indicated that -OH and -CONH2 groups were active center of biosorption.

Adsorption↗
PubMed2001

Activation of NF-kappa B in bronchial epithelial cells from children with asthma.

OBJECTIVES: To determine whether nuclear factor-kappa B (NF-kappa B) is activated in epithelial cells from children with asthma and to understand the role of NF-kappa B in airway inflammation in asthma. METHODS: Bronchial mucosa specimens were obtained from 9 children with asthma and 6 control subjects. NF-kappa B expression in epithelial cells were detected by immunohistochemical examination, and NF-kappa B-DNA binding was measured by electrophoretic mobility shift assay (EMSA). RESULTS: Nuclear expression of NF-kappa B in epithelial cells was observed in the 9 asthmatic children. NF-kappa B-DNA binding was found in 4 asthmatic children (EMSA was performed in 6 asthmatic children). In contrast, both nuclear expression and NF-kappa B-DNA binding were absent in the 6 control subjects. CONCLUSION: These results indicated that NF-kappa B is activated in epithelial cells from asthmatic children and the NF-kappa B activation may be the basis for the increased expression of many inflammatory genes and for airway inflammation in asthma.

Asthma↗
PubMed2001

[Excimer laser in situ keratomileusis for severe ametropia after penetrating keratoplasty].

OBJECTIVE: To evaluate the effects of excimer laser in situ keratomileusis in correcting severe myopia and astigmatism after penetrating keratoplasty. METHODS: Excimer laser in situ keratomileusis was performed on ten eyes of ten patients to correct high ametropia in cases having previously undergone penetrating keratoplasty. RESULTS: After surgery, all grafts remained clear and no corneal graft rejection occurred during the follow-up period. The average spherical equivalent refraction decreased from minus sign11.85 D preoperatively to minus sign3.38 D postoperatively and the average cylinder from 6.75 D to 2.70 D. The highest cylinder correction achieved was 10.00 D. The mean uncorrected visual acuity improved from 0.1 to 0.8, the best one was 1.5, and the best corrected visual acuity (BCVA) improved from 0.8 to 1.1. In this group, BCVA was improved in all eyes. CONCLUSION: Excimer laser in situ keratomileusis is a safe and effective method to deal with the high ametropia after penetrating keratoplasty and shows its great prospect.

Adult↗
PubMed2001

[Purification and some properties of D-hydantoinase produced by Pseudomonas 2262].

A D-hydantoinase produced by Pseudomonas 2262 was purified to electrophoretic homogeneity by the steps of thermal treatment, (NH4)2SO4 fractionation and column chromatography with Q-Sepharose fast flow, phenyl-Sepharose fast flow and Superose 12. Purification of about 60 fold was achieved with an overall yield of 16%. The relative molecular mass of the native enzyme is 109 kD and that of subunit is 53.7 kD by the analysis of Native and SDS-PAGE as well as gel filtration respectively. Some properties of the enzyme such as the sensitivity to thiol reagent and the effects of metal ions, for instance inhibited by Zn2+ and activited by Mn2+, Mg2+ are identical to dihydropyrimidinase. The optimum temperature and pH for enzymatic catalysis are 70 degrees C and 8.0 respectively. The enzyme activity is stable under 60 degrees C and in the pH range of 6-10. The N-terminal sequence for 10 amino acid residues is MDKLIKNGTI.

Amidohydrolases↗
PubMed2001

[Effect of guizhi decoction on adenyl cyclase and phosphodiesterase in hypothalamus of rats models of fever and hypothermia].

OBJECTIVE: To observe the effect of Guizhi Decoction (GZD) on adenyl cyclase (AC) and phosphodiesterase (PDE) activities in hypothalamus of rat models of fever and hypothermia. METHODS: The AC and PDE activities in hypothalamus were determined using radio-isotope method. RESULTS: GZD could lower the AC activity in yeast induced fever rat model (P < 0.05), but cause rise of AC activity in aminopyrine induced hypothermia model (P < 0.05). No significant influence of GZD on PDE activity was shown in both fever or hypothermia models. CONCLUSION: The bi-directional thermo-regulation effect of GZD might be partially due to influence on AC activity.

Adenylyl Cyclases↗
PubMed2001

[Study on mutations in the connexin 26 gene among Chinese with nonsyndromic hearing loss].

OBJECTIVE: To study the relation between nonsyndromic hearing loss in Chinese and mutations in connexin 26 (Cx 26) gene and to explore the pathogenic mechanism. METHODS: One hundred and thirty-eight individuals from thirty-five pedigrees with nonsyndromic hearing loss, 99 children with sporadic nonsyndromic hearing loss and 100 normal adults as control were collected in present studies. The Cx 26 coding sequence was screened by single strand conformational polymorphism (SSCP) and analyzed by direct sequencing when SSCP shifts were observed. RESULTS: Five SSCP shifts in 2 pedigrees were observed. Homozygous deletion C at position 233-235 of Cx 26 cDNA, which resulted in frameshift mutation, was found in 2 pedigrees with nonsyndromic hearing loss. CONCLUSION: The hot-spot mutations of Cx 26 gene in Chinese with nonsyndromic hearing loss may be different from other ethnic groups. The 233-235 delC homozygous mutation of Cx 26 cDNA can result in autosomal recessive nonsyndromic hearing loss in Chinese population.

Adult↗
PubMed2001

[Titanium miniplate fixation in head and neck cancer surgery].

OBJECTIVE: To evaluate the rigid fixation with miniplates in head and neck cancer surgery. METHOD: A consecutive series of 40 patients with head and neck tumor underwent rigid fixation with the Martin titanium miniplates system in a 6 years period. The miniplates were used to fix bone graft reconstruction following mandible resection (n = 14), mandibulotomies for oral and oropharyngeal surgical access (n = 12), maxilla swinging for nasopharyngeal access (n = 11) and other purposes (n = 3). Twenty-three of all cases(57.5%) received perioperative radiotherapy with average doses of 60Gy at the osteotomy site. RESULTS: Eleven of the 40 patient (22%) developed plate related complication which included 5 infections, 3 mandibular osteonecroses, 1 plate exposure, 1 screw loose and 1 nonunion. Complications were more likely to occur in patients with perioperative radiation than patients without (39.1% versus 11.8%, P = 0.079). Except one case, All the uncomplicated dentulous patients demonstrated stable and good occlusion. Oral feeding usually started on the 3-4th day after surgery. There was no need for intermaxillary fixation. CONCLUSION: The miniplate provided stable mandibular or maxillary fixation and accurate repositioning, eliminated the need for intermaxillary fixation. The malleability and versatility of miniplate make it unique in bone graft shaping for mandibular reconstruction. Complication seems to be related to perioperative radiotherapy. Median or paramedian mandibular osteotomy, which is non-radiated region in most radiotherapy cases, is advocated.

Adolescent↗
PubMed2001

Intracellular redistribution of cardiac endothelin-1 receptor in rat during myocardial hypertrophy.

OBJECTIVE: In a model of rat cardiac hypertrophy, the changes in the distribution of ET-1 receptors in two subcellular fractions, the sarcolemma and the light vesicles during myocardial hypertrophy were studied. METHODS: Cardiac hypertrophy was produced by placing a constricting clip around the suprarenal abdominal aorta of rats, and ET-1 receptor was assayed with radioactive analysis method. RESULTS: It was found that plasma and ventricular ET-1 levels increased significantly on week 2 and week 4 of pressure overload. ET-1 binding studies showed that during myocardial hypertrophy, the maximum binding capacity (B(max)) was increased by 41% (P < 0.01) and 65% (P < 0.01) in sarcolemma in H-2 week and H-4 week groups, but was decreased by 24% (P < 0.01) and 21% (P < 0.01) in light vesicles. The sum of B(max) of sarcolemmal and light vesicle fractions was increased by 33% (P < 0.01) and 57% (P < 0.01) in group H-2 week and H-4 week, respectively. CONCLUSION: ET-1 receptors in rat heart were externalized from light vesicles to sarcolemma, which may contribute to the development of myocardial hypertrophy.

Animals↗
PubMed2000

Inactivation of germline mutant APC alleles by attenuated somatic mutations: a molecular genetic mechanism for attenuated familial adenomatous polyposis.

Germline mutations of the adenomatous polyposis coli (APC) tumor-suppressor gene result in familial adenomatous polyposis (FAP). Patients with FAP typically develop hundreds to thousands of benign colorectal tumors and early-onset colorectal cancer. A subset of germline APC mutations results in an attenuated FAP (AFAP) phenotype, in which patients develop fewer tumors and develop them at an older age. Although a genotype-phenotype correlation between the locations of APC germline mutations and the development of AFAP has been well documented, the mechanism for AFAP has not been well defined. We investigated the mechanism for AFAP in patients carrying a mutant APC allele (APC(AS9)) that has a mutation in the alternatively spliced region of exon 9. APC(AS9) was found to down-regulate beta-catenin-regulated transcription, the major tumor-suppressor function of APC, as did the wild-type APC. Mutation analysis showed that both APC(AS9) and the wild-type APC alleles were somatically mutated in most colorectal tumors from these patients. Functional analysis showed that 4666insA, a common somatic mutation in APC(AS9) in these tumors, did not inactivate the wild-type APC. Our results indicate that carriers of APC(AS9) develop fewer colorectal tumors than do typical patients with FAP because somatic inactivation of both APC alleles is necessary for colorectal tumorigenesis. However, these patients develop colorectal tumors more frequently than does the general population because APC(AS9) is inactivated by mutations that do not inactivate the wild-type APC.

Adenomatous Polyposis Coli↗
PubMed2000

FYVE-DSP1, a dual-specificity protein phosphatase containing an FYVE domain.

Dual-specificity protein phosphatases (DSPs) dephosphorylate proteins at Ser/Thr and Tyr. FYVE domain is a double zinc finger motif which specifically binds phosphatidylinositol(3)-phosphate. Here, we report a novel dual specificity phosphatase that contains a FYVE domain at the C-terminus. We designate the protein FYVE-DSP1. Molecular cloning yielded three isoforms of the enzyme presumably derived from alternate RNA splicing. Sequence alignment revealed that the catalytic phosphatase domain of FYVE-DSP1 closely resembled that of myotubularin, while its FYVE domain has all the conserved amino acid residues found in other proteins of the same family. Recombinant FYVE-DSP1 is partitioned in both cytosolic and membrane fractions. It dephosphorylates proteins phosphorylated on Ser, Thr, and Tyr residues and low molecular weight phosphatase substrate para-nitrophenylphosphate. It shows typical characteristics of other DSPs and protein tyrosine phosphatases (PTPs). These include inhibition by sodium vanadate and pervanadate, pH dependency, and inactivation by mutation of the key cysteinyl residue at the phosphatase signature motif. Finally, PCR analyses demonstrated that FYVE-DSP1 is widely distributed in human tissues but different spliced forms expressed differently.

Alternative Splicing↗
PubMed2000

Diverse karyotypic abnormalities of the c-myc locus associated with c-myc dysregulation and tumor progression in multiple myeloma.

Translocations involving c-myc and an Ig locus have been reported rarely in human multiple myeloma (MM). Using specific fluorescence in situ hybridization probes, we show complex karyotypic abnormalities of the c-myc or L-myc locus in 19 of 20 MM cell lines and approximately 50% of advanced primary MM tumors. These abnormalities include unusual and complex translocations and insertions that often juxtapose myc with an IgH or IgL locus. For two advanced primary MM tumors, some tumor cells contain a karyotypic abnormality of the c-myc locus, whereas other tumor cells do not, indicating that this karyotypic abnormality of c-myc occurs as a late event. All informative MM cell lines show monoallelic expression of c-myc. For Burkitt's lymphoma and mouse plasmacytoma tumors, balanced translocation that juxtaposes c-myc with one of the Ig loci is an early, invariant event that is mediated by B cell-specific DNA modification mechanisms. By contrast, for MM, dysregulation of c-myc apparently is caused principally by complex genomic rearrangements that occur during late stages of MM progression and do not involve B cell-specific DNA modification mechanisms.

Chromosome Aberrations↗
PubMed2000

Selective expression of Nkx-2.2 transcription factor in chicken oligodendrocyte progenitors and implications for the embryonic origin of oligodendrocytes.

Recent studies have demonstrated that oligodendrocytes originate from the ventral region of the developing spinal cord. However, the precise neuroepithelial origin of oligodendrocytes remains controversial, and the transcriptional control of oligodendrocyte lineage specification is largely unknown. Here we present evidence that oligodendrocytes in the embryonic chicken spinal cord can be generated from neuroepithelial cells that express the Nkx-2.2 homeodomain transcription factor. Nkx-2.2 expression is initially confined to a narrow stripe of neuroepithelium flanking the floor plate. Later, Nkx-2.2+ cells migrate ventrally and dorsolaterally into the surrounding gray and white matter regions where they undergo rapid proliferation. Double labeling experiments revealed that Nkx-2.2+ cells coexpress markers specific for oligodendrocyte progenitors, e.g., PDGFRalpha+, O4, and R-mAb antigens. In the brain, the Nkx-2.2 cells are also highly migratory and can generate oligodendrocytes. The persistent expression of the Nkx-2.2 homeodomain transcription factor in the oligodendrocyte lineage suggests its important role in the control of oligodendrocyte development.

Animals↗
PubMed2000

Effects of Agricultural Chemicals on DNA Sequence Diversity of Soil Microbial Community: A Study with RAPD Marker.

The DNA sequence diversities for microbial communities in four soils affected by agricultural chemicals (mainly triadimefon and ammonium bicarbonate and their intermediates) were evaluated by Random Amplified Polymorphic DNA (RAPD) analysis. Fourteen random primers were used to amplify RAPDs from four soil microbial community DNAs. The products of 12 primers were separated in gel and generated 155 reliable fragments, of which 134 were polymorphic. The richness, modified richness, Shannon-Weaver index, and a similarity coefficient of DNA were calculated to quantify the diversity to access DNA sequence diversities for four soil microbial communities. The results showed that agricultural chemicals affected soil microbial community diversity at the DNA level. The four soil microbial communities were distinguishable in terms of DNA sequence richness, modified richness, Shannon-Weaver index, and coefficient of DNA similarity. Analysis also showed that the amounts of organic C and microbial biomass C were low in the soil polluted by pesticide (mainly triadimefon and its intermediates), but high in the soil polluted by chemical fertilizer (mainly ammonium bicarbonate and its intermediates). The above results combined may indicate that pesticide pollution caused a decrease in the soil microbial biomass but kept high diversity at DNA level, compared with the control without chemical pollution. In contrast, chemical fertilizer pollution caused an increase in the soil biomass but decrease in the DNA diversity. The RAPD marker technique combined with analysis of soil microbial biomass appears to be an effective approach for studying the diversity of soil microbial communities, although the effects of PCR bias on community composition, such as dominating and rare populations in soils, on the diversity needed to be addressed further. </hea

Journal Article↗
PubMed2000

Complete nucleotide sequence and infectious cDNA clone of the RNA1 of a Chinese isolate of broad bean wilt virus 2.

The nucleotide sequence of the RNA1 of broad bean wilt virus 2 (BBWV2) isolate B935 has been determined from overlapping cDNA clones. It contains 5956 nucleotides in length excluding the 3' terminal poly(A) tail and contains a single long open reading frame (ORF) of 5613 nucleotides extending from nucleotide 234 to 5846. A repeated motif has been found in the 5' non-coding region. The predicted polyprotein encoded by the long ORF is 1870 amino acid in length with a molecular weight of 210 K. Amino acid sequence comparisons between portions of the BBWV2 RNA1-encoded polyprotein and proteins encoded by several species in Comoviridae revealed the putative functions of BBWV2 RNA1-encoded proteins and the same general genetic organization as that of comoviruses and nepoviruses. Based on the determined sequence, full-length cDNA clone of RNA1 designated as pU1FL was constructed. Together with transcripts from full-length cDNA clone of RNA2 (pU2FL), transcripts from pU1FL infected Chenopodium quinoa successfully.

Amino Acid Motifs↗