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X Qian

Publications and source records attributed to X Qian.

At least 19 recordsLinked to original sources
PubMed2004

Selective inhibition of beta-globin RNA transcripts by antisense RNA molecules.

Inhibition of beta-globin gene expression by antisense nucleic acids is a potentially powerful therapeutic strategy for sickle cell disease. To develop clinically relevant beta-globin antisense agents we created nine stable mouse erythroleukemia cell lines expressing unique anti-beta-globin RNA transcripts with different potentials for cross-hybridization with gamma-globin mRNA. We observed variable inhibition of beta-globin expression independent of the hybridization potential of the respective antisense beta-globin RNA transcript. Similarly, inhibition of gamma-globin expression by anti-beta transcripts varied widely in the nine stable cell lines. Three neighboring regions in the beta-globin gene with low RNA folding potentials conferred significantly stronger antisense effect toward beta-globin while sparing the homologous targets in gamma-globin. We have identified for the first time targets in the beta-globin gene for which the homologous regions in gamma-globin are relatively inaccessible to antisense attack. Our findings offer the prospect of using this approach to reduce the proportion of intracellular hemoglobin S. Gene therapy strategies which combine gamma-globin induction along with beta-globin inhibition using antisense vectors may yield more favorable anti-sickling effects longterm.

Animals↗
PubMed2003

In situ hybridization for the differentiation of Aspergillus, Fusarium, and Pseudallescheria species in tissue section.

Identification of fungi in tissue sections can be difficult. In particular, species of Aspergillus, Fusarium, and Pseudallescheria all appear as septate, branched hyphae. However, their differentiation can have significant clinical implications, as the latter two groups are often resistant to commonly used antifungal agents. In situ hybridization may assist in rapidly distinguishing these organisms in the absence of available culture. Oligonucleotide DNA probes were directed against the 5S, 18S, or 28S rRNA sequences of three groups of fungi with a high degree of specificity for each. Probes were tested on 26 formalin-fixed, paraffin-embedded tissue specimens, each with culture-proven involvement by one of these organisms: Fusarium species, n = 12; Pseudallescheria boydii, n = 5; Aspergillus species, n = 9 ( probe set validated in an earlier study). Accuracy of both ISH and morphology was compared with culture. Morphologic examination (GMS and PAS) showed a greater sensitivity in detecting fungi (100%) as compared with in situ hybridization (84.6%). When detected, however, DNA probes allowed definitive identification of organisms. While there was no ability to distinguish between the three groups of organisms by morphologic features, ISH probes showed 100% positive predictive value (PPV, 19/19 organisms identified correctly). No cross-reactivity was observed when the probes were tested against other genera (100% specificity). Furthermore, the use of ISH allowed the detection of mixed fungal infections involving multiple organism types in two cases, demonstrating another advantage over morphology. In situ hybridization, directed against rRNA sequences, provides a rapid and accurate technique for distinguishing commonly encountered, nonpigmented filamentous fungi in histologic sections. While less sensitive than morphology, ISH is highly accurate and may help to distinguish between organisms that have similar or identical morphologic features by light microscopy.

Aspergillus↗
PubMed2002

An artificial peptide with corticotropin-releasing factor receptor-2 (CRF-R2) selective properties: the role of primary structure in the induction of signal transduction pathways.

Considerable plasticity can occur within the amino acid sequence of amphiphilic peptide hormones. This is particularly evident within the corticotropin-releasing factor (CRF) family of peptides where, despite less than 15% sequence similarity among the four paralogous lineages, all are capable of acting as high affinity ligands to members of the CRF receptor family. This suggests that these peptides could undergo many mutational changes and remain as high affinity ligands to their receptors as long as the functional motifs do not change radically. Because paralogous peptide lineages are a product of genome duplications, additional genes encoding peptide-like sequences, which through mutation have lost their functional integrity, may exist. Function to these sequences may be restored if the appropriate motifs are reinserted into the primary structure. We screened rat genomic DNA with highly degenerate polymerase chain reaction (PCR) primers targeted to hybridize with the termini of CRF-related sequences. One set of sauvagine-based primers hybridized with a 120-bp sequence. The theoretical peptide sequence (SV4) showed similarity to the CRF family of peptides at the primary structure level. The encoded sequence was prepared by solid-phase synthesis and its activity assayed against mouse R1 and human R1/R2 receptors. SV4 did not bind to either mouse or human variants of the R1 receptor, but did bind to the R2 receptor with an affinity comparable to human CRF. SV4 exhibited a similar efficacy of cellular activation as CRF in trials quantifying the acidification rate of human R2alpha-transfected Chinese hamster ovary (CHO) cells, but not R1-transfected cells. SV4 utilizes adenylate cyclase as the principal secondary messenger of R2 signal transduction but, unlike urocortin or sauvagine, does not activate guanylate cyclase-, calcium- or mitogen-activated protein (MAP) kinase-mediated pathways. These data suggest that this artificial peptide may be useful to understand the cyclic adenosine monophosphate (cAMP)-dependent component of the CRF-R2 signal transduction cascade, and that additional sequences in the genome may be used to engineer bioactive peptides.

Amino Acid Sequence↗
PubMed2002

Mothers' perspectives on the quality of postpartum care in Central Shanghai, China.

OBJECTIVES: To investigate mothers' perspectives on the quality of postpartum care services in central Shanghai, China. DESIGN: Semi-structured interviews. SETTING: Two maternal and child health posts in two subdistricts in LW District, Central Shanghai, China. STUDY PARTICIPANTS: Fifty postpartum mothers who attended the maternal and child health posts in the two subdistricts in LW District, Central Shanghai, China. MAIN OUTCOME MEASURES: Mothers' perceived quality and adequacy of postpartum services. RESULTS: A majority of the mothers (90%; n = 45) were primiparas (first time mothers). Half did not consider the postpartum services to be of high quality. They defined high quality as 'full satisfaction of the mother and the child'. Their perception of quality was influenced by their concern about child care, an area in which they expressed the need for further improvement. CONCLUSION: Mothers indicated that to improve quality of services further, greater emphasis should be placed on: (1) health education on childcare; (2) more time allocation for discussion with health workers during their postpartum home visits so their questions and concerns could be addressed effectively; (3) access to health workers in times of need rather than during officially prescribed home visits; and (4) provision of continuous training for maternal and child health workers with respect to childcare. The findings will be relevant to health workers and policy makers involved in planning and implementation of maternal and child health services in similar urban settings in developing countries.

China↗
PubMed2002

In situ hybridization for the identification of filamentous fungi in tissue section.

Identification of fungi in tissue sections can be difficult because of limited biopsy tissue with only a few organisms present, or mycelial elements may be the only forms present, rendering common organism types indistinguishable from one another. In situ hybridization may assist in the rapid and accurate identification of such fungi. In this study, DNA probes were directed against the 5S or 18S ribosomal RNA sequences of three groups of fungi with a high degree of specificity for each. Two of the three, Aspergillus and Zygomycetes species, are usually seen in tissue purely in their hyphal forms. The third, Candida species is seen less commonly as predominantly mycelial elements. Probes were tested on 61 formalin-fixed, paraffin-embedded tissue specimens, each with culture-proven involvement by one of these organisms (Candida species, n = 21; Aspergillus species, n = 27; Zygomycetes, n = 13). Accuracy of both in situ hybridization (ISH) and morphology, based on the examination of Grocott methanamine silver (GMS)- and periodic acid-Schiff (PAS)-stained slides, was compared with culture. The results showed that morphologic examination (GMS and PAS) showed a slightly greater sensitivity in detecting the presence of fungi (98%) compared with in situ hybridization (95%). DNA probes, however, were more accurate in correctly identifying those organisms present. Although ISH specific probes showed 97% positive predictive value (PPV), examination of GMS-and PAS-stained slides had an 86% PPV when compared with culture-based identification methods. These results show that ISH, directed against ribosomal RNA, provides a rapid and accurate technique for the identification of mycelial fungal organisms in histologic tissue sections. Its primary use lies in the ability to accurately distinguish between organisms that have similar or identical morphologic features by light microscopy.

DNA Probes↗
PubMed2001

[The effects of heat shock protein 90 and glucocorticoid receptor on apoptosis in T lymphocytes from asthmatic patients].

OBJECTIVE: Using GA (geldanamycine), which specifically binding to HSP90, to induce the imbalance of HSP90/GR in function (low ratio) and analyzing the effect of low HSP90/GR ratio on T lymphocytes apoptosis induced by Dex from asthmatic patients. The expression of HSP90 and GR mRNA of T lymphocytes influenced by Dex and GA was also studied. METHODS: Peripheral blood T lymphocytes were enriched from 10 asthmatic subjects and 7 healthy volunteers by nylon column. T lymphocytes were cultured in vitro with Dex and / or GA for 72 hours. Apoptosis of T lymphocytes were measured by propidium iodide staining and flowcytometry. With reverse transcription-polymerase chain reaction (RT-PCR), the expression of HSP90 and GR mRNA was detected. RESULTS: Dex could obviously induce the apoptosis of T lymphocytes from asthmatic patients (33.8% +/- 3.2% vs 23.2% +/- 1.5% , P < 0.01). GA had no effect on the apoptosis of T lymphocytes but could inhibit the effect of Dex (24.5% +/- 6.0% vs 33.8% +/- 3.2% , P < 0.01). Dex also had the effect of inducing apoptosis of T lymphocytes from health volunteers but the effect was less potent than that from asthmatic patients (25.9% +/- 3.5% vs 23.1% +/- 1.5 %, P < 0.05). Dex inhibited the expression of HSP90 and GR mRNA of T lymphocytes from asthmatic patients (1.23 +/- 0.16 vs 1.68 +/- 0.38 and 0.42 +/- 0.06 vs 0.54 +/- 0.07, respectively, P all < 0.05). GA could interrupt the inhibiting effect of Dex on the expression of HSP90 and GR mRNA but had no effect on it. CONCLUSION: The low ratio of HSP90/GR could reduce the inducing apoptosis effect of Dex. Dex could down-regulate the mRNA expression of HSP90 and GR and GA could interrupt the inhibiting effect of Dex.

Adult↗
PubMed2001

Evidence for a novel natriuretic peptide receptor that prefers brain natriuretic peptide over atrial natriuretic peptide.

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) exert their physiological actions by binding to natriuretic peptide receptor A (NPRA), a receptor guanylate cyclase (rGC) that synthesizes cGMP in response to both ligands. The family of rGCs is rapidly expanding, and it is plausible that there might be additional, as yet undiscovered, rGCs whose function is to provide alternative signalling pathways for one or both of these peptides, particularly given the low affinity of NPRA for BNP. We have investigated this hypothesis, using a genetically modified (knockout) mouse in which the gene encoding NPRA has been disrupted. Enzyme assays and NPRA-specific Western blots performed on tissues from wild-type mice demonstrate that ANP-activated cGMP synthesis provides a good index of NPRA protein expression, which ranges from maximal in adrenal gland, lung, kidney, and testis to minimal in heart and colon. In contrast, immunoreactive NPRA is not detectable in tissues isolated from NPRA knockout animals and ANP- and BNP-stimulatable GC activities are markedly reduced in all mutant tissues. However, testis and adrenal gland retain statistically significant, high-affinity responses to BNP. This residual response to BNP cannot be accounted for by natriuretic peptide receptor B, or any other known mammalian rGC, suggesting the presence of a novel receptor in these tissues that prefers BNP over ANP.

Adrenal Glands↗
PubMed2001

Dynamic simulations of 13 TATA variants refine kinetic hypotheses of sequence/activity relationships.

The fundamental relationship between DNA sequence/deformability and biological function has attracted numerous experimental and theoretical studies. A classic prototype system used for such studies in eukaryotes is the complex between the TATA element transcriptional regulator and the TATA-box binding protein (TBP). The recent crystallographic study by Burley and co-workers demonstrated the remarkable structural similarity contrasted to different transcriptional activity of 11 TBP/DNA complexes in which the DNAs differed by single base-pairs. By simulating these TATA variants and two other single base-pair variants that were not crystallizable, we uncover sequence-dependent structural, energetic, and flexibility properties that tailor TATA elements to TBP interactions, complementing many previous studies by refining kinetic hypotheses on sequence/activity correlations. The factors that combine to produce favorable elements for TBP activity include overall flexibility; minor groove widening, as well as roll, rise, and shift increases at the ends of the TATA element; untwisting within the TATA element accompanied by large roll at the TATA element ends; and relatively low maximal water densities around the DNA. These features accompany the severe deformation induced by the minor-groove binding protein, which kinks the TATA element at the ends and displaces local water molecules to form stabilizing hydrophobic contacts. Interestingly, the preferred bending direction itself is not a significant predictor of activity disposition, although certain variants (such as wild-type AdMLP, 5'-TATA4G-3', and inactive A29, 5'-TA6G-3') exhibit large preferred bends in directions consistent with their activity or inactivity (major groove and minor groove bends, respectively). These structural, flexibility, and hydration preferences, identified here and connected to a new crystallographic study of a larger group of DNA variants than reported to date, highlight the profound influence of single base-pair DNA variations on DNA motion. Our refined kinetic hypothesis suggests the functional implications of these motions in a kinetic model of TATA/TBP recognition, inviting further theoretical and experimental research.

Base Sequence↗
PubMed2001

Cloning, expression, purification and preliminary X-ray crystallographic studies of yeast Hsp40 Sis1 complexed with Hsp70 Ssa1 C-terminal lid domain.

Heat-shock protein 70 (Hsp70) plays essential roles in a number of cellular processes such as protein folding, assembly and translocation. Heat-shock protein 40 (Hsp40) transiently interacts with Hsp70 and facilitates Hsp70 functions in these processes within cells. Hsp40 recognizes and binds non-native polypeptide and delivers it to Hsp70. Hsp40 can then stimulate the ATPase activity of Hsp70 to refold the polypeptide. To investigate the molecular mechanism by which Hsp40 interacts with Hsp70 to transport the non-native polypeptide, Saccharomyces cerevisiae Hsp40 Sis1 C-terminal peptide-binding fragment complexed with Hsp70 Ssa1 C-terminal lid domain has been produced and crystallized. The complex crystals diffract to 3.3 A and belong to the space group P4(1)2(1)2 or P4(3)2(1)2, with unit-cell parameters a = 112.17, c = 171.31 A. Structure determination by the MAD method is under way.

Adenosine Triphosphatases↗
PubMed2001

Proteomic analysis of apoptosis initiation induced by all-trans retinoic acid in human acute promyelocytic leukemia cells.

The irreversible destiny of apoptosis in its early stage might play a critical role in the apoptosis of human acute promyelocytic leukemia (APL) cell line induced by all-trans retinoic acid (ATRA). To characterize protein alterations during the apoptosis-initiation phase and to understand the metabolic status at that time, we investigated the protein profiles in the apoptosis-initiation phase of APL cell line HL-60 by proteomic analysis. ATRA-withdrawal was conducted to demonstrate that there was committed initiation phase of apoptosis triggered by 10(-6) M ATRA at day 3. Only after that time point, ATRA-treated cells irreversibly went to apoptosis. Also at that time point, the positive regulators of apoptosis such as STAT3 increased at protein level, whereas negative regulators (Bcl-2 and p-STAT3) decreased. In addition, caspase-3 also increased after that time. Furthermore, comparative proteomic analysis was utilized to examine the protein expression profiles during the initiation stage of apoptosis. Our results showed 12 upregulated and 7 downregulated proteins experiencing twofold alteration, including key regulators of signal transduction such as G-proteins and nucleic receptors, proteins related with metabolism, oxidation and reduction, proteins associated with the nucleus and cytoskeleton-related proteins. Some of them could be positive modulators to trigger apoptosis, whereas others could contribute to intracellular defense against apoptosis induced by exogenous triggers. The results above suggest that there is a subtle balance between apoptosis and the intracellular defense against apoptosis. Once the balance is disturbed, cells would irreversibly initiate to undergo the execution of apoptosis.

Amino Acids↗
PubMed2001

Proteomic characterization of early-stage differentiation of mouse embryonic stem cells into neural cells induced by all-trans retinoic acid in vitro.

Embryonic stem (ES) cells are totipotent stem cells, which can differentiate into various kinds of cell types, including neurons. They are widely used as a model system for investigating mechanisms of differentiation events during early mouse development. In this study, proteomic techniques were used to approach the protein profile associated with the early-stage differentiation of ES cells into neuronal cells induced by all-trans retinoic acid (ATRA) in vitro. In comparison of the protein profile of parent ES cells with that of ES-derived neural-committed cells, which was induced by ATRA for four days, 24 differentially displayed protein spots were selected from two-dimensional electrophoresis (2-DE) gels for further protein identification by pepide mass fingerprinting (PMF). Nine proteins were known to being involved in the process of neural differentiation and/or neural survival. Of those, alpha-3/alpha-7 tubulin and vimentin were down-regulated, while cytokeratin 8, cytokeratin 18, G1/S-special cyclin D2, follistatin-related protein, NEL protein, platelet-activating factor acetylhydrolase IB alpha-subunit, and thioredoxin peroxidase 2 were upregulated during differentiation of ES cells to neural cells. Additionally, other 12 protein (five upregulated and seven downregulated) spots associated with ES cell differentiation into neuronal cells were not matched to known proteins so far, implicating that they might be novel proteins. The results above indicated that the molecular mechanisms of differentiation of ES cells to neural cells in vitro might be similar to those of other neural systems in vitro and identified that proteomic analysis is an effective strategy to comprehensively unravel the regulatory network of differentiation.

Animals↗
PubMed2001

Expression of thrombospondin-1 in human pancreatic adenocarcinomas: role in matrix metalloproteinase-9 production.

Human pancreatic adenocarcinoma, an aggressive malignant disease, shows a strong desmoplastic reaction characterized by a remarkable proliferation of interstitial connective tissues. Thrombospondin-1 (TSP-1), a 450 kDa platelet and matrix glycoprotein, has been implicated in tumor invasion, angiogenesis and metastasis. TSP-1 and MMP-9 expression in pancreatic adenocarcinoma and control pancreas tissues was measured by immunohistochemistry. TSP-1 expression in pancreatic carcinoma cell lines, fibroblasts, and endothelial cells was measured by a competitive TSP-1 enzyme linked immunosorbent assay (ELISA). The effect of TSP-1 on MMP-9 production in pancreatic carcinoma cell lines was measured by zymography and Western blot analysis. Eighty five per cent (23/27) of cases of pancreatic adenocarcinoma showed increased TSP-1 staining in the desmoplastic stroma adjacent to tumor cells. No specific positive staining for TSP-1 was observed in the normal pancreatic tissues and the inflammatory areas. TSP-1 localized in tumor stroma surrounding the tumor cells expressing MMP-9. Using TSP-1 competitive ELISA, the secretion of TSP-1 by different pancreatic cancer cell lines into culture medium varied from 11.45 plus minus 14.08 to 275.82 plus minus 45.56 ng/10 6 cells/24 hours. The amounts of TSP-1 detected in both culture media and cell extracts from fibroblasts or endothelial cells were at least 2-3 fold higher than those from pancreatic cancer cells. TSP-1 augmented the production of matrix metalloproteinase-9, a matrix degrading enzyme, in pancreatic cancer cells in vitro. Stromally-derived TSP-1 up-regulates the production of MMP-9 by pancreatic adenocarcinoma. These data are consistent with the conclusion that TSP-1-rich stroma is involved in regulating matrix remodeling in tumor invasion.

Adenocarcinoma↗
PubMed2001

A new operation for ventricular septal defect with aortic incompetence.

Two boys, 10 years of age, with ventricular septal defect and severe aortic insufficiency were treated using a new method. An autograft of anterior pulmonary artery wall and the adjacent leaflet and subpulmonary muscle was excised. The excised pulmonary artery segment was used to replace the prolapsed right coronary cusp, and the autograft muscle was used to close the ventricular septal defect. The right ventricular outflow tract and pulmonary valve were repaired using an autologous pericardial patch with an autologous single cusp. The results in both cases were satisfactory.

Aortic Valve Insufficiency↗
PubMed2001

Long-term survival of cardiac xenografts in fully xenogeneic (mouse --> rat) bone marrow chimeras.

BACKGROUND: The shortage of human hearts remains a major barrier to the efficacy of heart transplantation for the treatment of end-stage heart disease. One potential solution to the supply problem would be the use of hearts from nonhuman donors (xenografts). We have established a model of mouse to rat xenogeneic bone marrow chimerism, and in this study we have hypothesized that such chimeric rats will accept both donor and recipient specific heart grafts while rejecting third-party mouse and rat grafts. We also investigated humoral responses in naive and chimeric rats with and without donor murine cardiac grafts. METHODS: Recipient Lewis rats (n = 22) were given 1100 cGy lethal total body irradiation and the same day received 300 x 10(6) donor B10.BR mouse bone marrow cells intravenously. Peripheral blood of surviving rats (n = 18) was typed at 4 weeks and then monthly thereafter. Donor and recipient specific and third-party heterotopic heart transplantations were performed at 6 to 8 weeks after reconstitution with bone marrow. RESULTS: Multilineage bone marrow chimerism was produced in all experimental animals with complete replacement of recipient marrow by donor cells. Murine donor and rat recipient strain hearts transplanted in chimeric rats survived indefinitely. Third-party rat and mouse hearts were rejected, though at a slower rate than bone marrow matched naive controls. High levels of antimouse antibodies were detected in rats with rejected hearts. These antibodies were absent in chimeric animals with long-term surviving heart grafts. CONCLUSIONS: Long-term multilineage bone marrow chimerism can be produced in a mouse --> rat bone marrow transplant model. Long-term survival of donor specific and recipient specific vascularized cardiac grafts can be produced in these chimeric animals. These animals are clinically normal but show signs of subclinical immunosuppression regimen as they reject third-party hearts later than naive animals. Our results suggest that antibodies also play a significant role in concordant xenograft rejection, and induction of bone marrow chimerism can overcome this barrier.

Animals↗
PubMed2001

Synthesis and quantitative structure-activity relationships of new 2,5-disubstituted-1,3,4-oxadiazoles.

Fourteen new 2,5-disubstituted-1,3,4-oxadiazoles, namely (i) six 2-[2,2-dimethyl-3-(2,2-dichlorovinyl)-cyclopropyl]-5-substituted-1,3,4-oxadiazoles and (ii) eight 2-substituted-phenoxymethyl-5-substituted-aryl-1,3,4-oxadiazoles, were synthesized and evaluated for their insect growth regulatory activity against second-instar larvae of armyworm (Pseudaletia separata Walker). Two of these compounds (7 and 8) showed good insecticidal activities, with LC(50) values of 14.33 and 15.85 microg/mL, respectively. Steric parameters (e.g., the molecular length d and the ratio of the nonpolar surface area and polar surface area V(1)/V(2)) and semiempirical quantum parameters (e.g., the molecular total energy E(t) and the lowest unoccupied molecular orbital energy E(LUMO) and so on) of these compounds, as well as those of six other 2,5-disubstituted-1,3,4-oxadiazoles reported, were acquired by the molecular modeling method and the PM3-SCF-MO method, respectively. With the help of the synthons' activity contribution method based on the Free-Wilson approach in its Fujita-Ban variant, quantitative structure-activity relationships were studied by regressing half-lethal concentrations against the above parameters.

Animals↗