Search PubMed⌕ Search

Biomedical subjects

Q Zhao

Publications and source records attributed to Q Zhao.

At least 73 records · Page 4Linked to original sources
PubMed2001

Role of beta-adrenoceptor at different stages of bronchial asthma.

OBJECTIVE: To investigate the changes of beta-adrenergic receptor (beta AR) in peripheral lymphocytes and beta 2AR mRNA levels at different stages of bronchial asthma. METHODS: beta 2AR density and beta 2AR mRNA level in peripheral lymphocytes, cAMP and cGMP levels in blood plasma were estimated by radioligand binding assay, radioimmunoassay and RT-PCR. RESULTS: (1) Maximum bound volume (Bmax) and equilibrium dissociation constant (Kd) of beta 2AR of lymphocyte in asthma patients at remission stage were markedly higher than that in normal subjects, while cAMP levels in blood plasma showed no difference. Bmax of beta 2AR and cAMP levels in asthma patients at acute exacerbation stage were significantly lower than that in normal subjects, and Kds between these two groups were not much different. (2) Expression of beta 2ARmRNA in peripheral lymphocytes of asthmatics at remission stage was not significantly different compared with that in normals. CONCLUSIONS: Amount and function of beta AR and beta 2ARmRNA levels are related to asthmatic conditions. Changes of beta AR and beta 2ARmRNA in asthma might rather be a pathological change accompanied by the course of the disease than a primary defect.

Adult↗
PubMed2001

[Studies on the cell suspension culture of Saussarea medusa in a stirred tank bioreactor].

The cell suspension culture of Saussarea medusa in a 2L aerated and agitated bioreactor with a four-pitch-blade impeller was investigated. The effects of agitation speed, aeration and inoculum size on cell growth and flavonoids production were studied and it was found that cells had optimum growth and flavonoids production when cultivated at 75 r/min, 700-1000 L/min and an inoculum of 4.0-5.0 g/L. A high cell biomass of 13.8 g/L and flavonoids production of 416 mg/L were achieved after 12 days of cultivation. Time course study revealed that flavonoids biosynthesis was growth-associated. The studies on aggregates size distribution in the bioreactor showed that the aggregates break-up caused by hydrodynamic stress might adversely affect cell growth and lead to significant reduction of cell biomass and flavonoids production.

Bioreactors↗
PubMed2001

[The remineralization of enamel lesions by casein phosphopeptide-amorphous calcium fluoride phosphate in vitro].

OBJECTIVE: To evaluate the remineralizing effect on artificial enamel subsurface lesions in vitro by 2% casein phosphopeptide-amorphous calcium fluoride phosphate complexes (CPP-ACFP) solution. METHODS: Twenty-eight enamel blocks were cut from human third molars, in which 2 lesions were prepared from each block. The 28 samples were randomly assigned to the four study groups, in which each group was incubated in remineralization solution for 1, 3, 5, 10 days respectively. After remineralization the samples were sectioned, microradiographied and the mineral content were determined by microdensitometry. RESULTS: The remineralizing solution replaced 9.19%, 14.27%, 29.07%, 38.45% of mineral lost after 1, 3, 5, 10 days respectively (y = 8.9316 x0.6347, R2 = 0.9322; y: remineralizing rate, x: time). Significant differences were found in remineralizing rate between any two groups using One-way Scheffe multiple comparison. CONCLUSIONS: The 2% CPP-ACFP solution could significantly remineralize the artificial enamel subsurface lesion in vitro. The remineralizing rates were increased with the experiment time (within 10 days).

Caseins↗
PubMed2001

[The influential factors on DNA cycle sequencing and data evaluation of practical example].

OBJECTIVE: To study some factors that may influence DNA sequencing by analyzing 2040 sequencing samples retrospectively. METHODS: The effects of DNA templates, primers, cycle sequencing reactions as well as purification methods were comparatively analyzed. RESULTS: 70 percent of sequencing failure is caused by DNA template. Characteristics of data from poor template preparation include top-heavy with a short read length, acceptable signal with some noise peaks (Ns), weak signal, overall noise and flat lines or no signal. The ineffective primers can cause 15.4 percent sequencing failure. Possible explanations include primer mismatches and low Tm value. CONCLUSIONS: The quality of template DNA can have a major impact on the quality of the DNA sequencing. Purification of the extension products is absolutely necessary in DNA sequencing, and isopropanol precipitation is highly recommended for this procedure.

Animals↗
PubMed2001

[A study on tongue cancer cell labeling using bromodeoxyuridine (BrdU) incorporation in vitro].

OBJECTIVE: The aim of this study is to evaluate of Bromodeoxyuridine (BrdU) label in the proliferation of the tongue cancer. METHODS: The authors used 80 micrograms/ml BrdU or iododeoxyuridine (IdU) to label three cases of fresh tissue of tongue cancer and four bottles of Tca8113 cells in logarithmic growth period in vitro. They were fixed and embedded in the routine procedure, and then in serial sections. These specimens were labeled with BrdU polyclonal antibody (1:200), and PCNA monoclonal antibody (1:100), stained using immunohistochemical ABC method. The authors observed the shapes and sizes of those positive cells, counted their label indexes (LI) of BrdU- or IdU-positive cells and PCNA- positive cells respectively. Four bottles of Tca8113 cells were cultured for 1-4 days. One bottle of the cells was every day used in the experimental study about comparing the cells labeled BrdU with those of the S phase of FCM in same cultural time. RESULTS: The positive cells generally owned a larger round nucleus, sometimes in company with sister cells. There was no difference of positive cells in these two kinds of labeling methods between the incorporation of BrdU or IdU and the expression of proliferating cell nuclear antigen (P > 0.05). The cells of S phase with FCM method were much more than that method with BrdU incorporation (P < 0.001). CONCLUSION: The method of BrdU labeling could be used in tumor cellular proliferation studies.

Bromodeoxyuridine↗
PubMed2001

[Effect of shenqi fuzheng injection on immune function in gastric carcinoma patients in post-operational and chemotherapeutic period].

OBJECTIVE: To investigate the effect of Shenqi Fuzheng injection (SQFZI) on immune function in gastric carcinoma patients in post-operational and chemotherapeutic period. METHODS: One hundred and twenty-three gastric carcinoma post-operational patients and 36 cases of gastric carcinoma patients on chemotherapy, according to their using SQFZI or not, parameters of immune function, including red blood cell C3b receptor rosette (RBC-C3bRR) and immune complex rosette (RBC-ICR), T-lymphocyte subsets and NK cell activity were determined. RESULTS: RBC-C3bRR, CD3, CD4 and NK cell activity were significantly higher, but RBC-ICR was lower in patients of post-operational period treated with SQFZI than those in patients untreated with SQFZI (P < 0.01). The same difference also revealed between the patients in chemotherapeutic period treated and untreated with SQFZI (P < 0.01). CONCLUSION: The immune function of gastric carcinoma patients in post-operational or chemotherapeutic period could be effectively improved by addition of SQFZI.

Adjuvants, Immunologic↗
PubMed2001

Association between low-density lipoprotein receptor-related protein gene, butyrylcholinesterase gene and Alzheimer' s disease in Chinese.

OBJECTIVE: To research the relations between low-density lipoprotein receptor-related protein gene (LRP) polymorphism, butyrylcholinesterase gene (BchE) polymorphism and Alzheimer's disease (AD) in Chinese. METHODS: The gene polymorphisms of LRP and BchE were genotyped in 38 AD cases and 40 controls with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. AD groups were classified according to the LRP C/C genotype and compared with matched controls. RESULTS: AD group had higher frequencies of C/C homozygote (81.69% vs 60.0%, P < 0.05) and of C allele (89.5% vs 76.3%, P < 0.05), with no significant difference between any of these LRP genotypes classified AD groups and their respective control groups. CONCLUSIONS: A positive correlation was found between LRP gene polymorphism and AD, but not between BchE gene polymorphism and AD in Chinese AD cases.

Aged↗
PubMed2001

[Differentiation and malignant suppression induced by mouse erythroid differentiation and denucleation factor on mouse erythroleukemia cells].

OBJECTIVE: To investigate the roles of mouse erythroid differentiation and denucleation factor (MEDDF), newly cloned in our laboratory, in erythroid terminal differentiation. METHODS: Mouse erythroleukemia cells (MEL) were transfected with eukaryotic expression plasmid pcDNA-MEDDF. The changes of cell growth rate, mitotic index and colony-forming rate in semi-solid medium were investigated. The expressions of c-myc and beta-globin genes were analysed by semi-quantitative RT-PCR. RESULTS: MEL cells transfected with pcDNA-MEDDF showed significant lower growth rate, mitotic index, and colony-forming rate in semisolid medium(P < 0.01). The percentage of benzidine-positive cells was 32.8% after transfection. The expression of beta-globin in cells transfected with pcDNA-MEDDF was 3.43 times higher than that of control (MEL transfected with blank vector, pcDNA3.1), and the expression of c-myc was decreased by 66.3%. CONCLUSIONS: MEDDF can induce differentiation of MEL cell, and suppress its malignancy likely.

Activins↗
PubMed2000

Accessible 5'-end of CpG-containing phosphorothioate oligodeoxynucleotides is essential for immunostimulatory activity.

In our ongoing efforts to decipher the sequence and structural requirements in the flanking region of the CpG motif in phosphorothioate oligodeoxynucleotides (PS-oligos), we have examined the requirement of free 5'- and 3'-ends of PS-oligos on immune stimulation. Our model studies using 3'-3'-linked (containing two free 5'-ends) and 5'-5'-linked (containing two free 3'-ends) CpG-containing PS-oligos demonstrate that immunostimulatory activity is significantly reduced when the 5'-end of the PS-oligo is not accessible, rather than the 3'-end, suggesting that the 5'-end plays a critical role in immunostimulatory activity.

Adjuvants, Immunologic↗
PubMed2000

Identification of a novel sequence involved in lysosomal sorting of the sphingolipid activator protein prosaposin.

Prosaposin is synthesized as a 53-kDa protein, post-translationally modified to a 65-kDa form and further glycosylated to a 70-kDa secretory product. The 65-kDa protein is associated to Golgi membranes and is targeted to lysosomes, where four smaller nonenzymatic saposins implicated in the hydrolysis of sphingolipids are generated by its partial proteolysis. The targeting of the 65-kDa protein to lysosomes is not mediated by the mannose 6-phosphate receptor. The Golgi apparatus appears to accomplish the molecular sorting of the 65-kDa prosaposin by decoding a signal from its amino acid backbone. This investigation deals with the characterization of the sequence involved in this process by deleting the saposin functional domains A, B, C, and D and the highly conserved N and C termini of prosaposin. The truncated cDNAs were subcloned into expression vectors and transfected to COS-7 cells. The destination of the mutated proteins was assessed by immunocytochemistry. Deletion of the C terminus did not interfere with the secretion of prosaposin but abolished its transport to lysosomes. Deletion of saposins and the N-terminal domain did not affect the lysosomal or secretory routing of prosaposin. A chimeric construct of albumin and the C terminus of prosaposin was not directed to lysosomes. However, albumin connected to the C terminus and one or more functional domains of prosaposin reached lysosomes, indicating that the C terminus and at least one saposin domain are required for this process. In summary, we are reporting a novel sequence involved in the targeting of prosaposin to lysosomes.

Amino Acid Sequence↗
PubMed2000

Immunostimulatory activity of CpG containing phosphorothioate oligodeoxynucleotide is modulated by modification of a single deoxynucleoside.

Phosphorothioate oligodeoxynucleotides (PS-oligos) containing the CpG motif have immunostimulatory properties. Our earlier study had shown that the immunostimulatory activity of PS-oligos containing the CpG motif can be modulated by incorporation of 2'-O-methylribonucleosides (Zhao, Q.; Yu, D.; Agrawal, S. Bioorg. Med. Chem. Lett. 1999, 9, 3453). Here we show that the immunostimulatory activity of a PS-oligo containing a CpG motif can be modulated by substitution of a single deoxynucleoside at specific sites with either 2'-O-methylribonucleoside or 3'-O-methylribonucleoside in the flanking region to CpG motif. Furthermore, substitution of deoxynucleosides with 2'-O-methoxyethoxyribonucleosides also results in modulating immunostimulatory activity of PS-oligos.

Animals↗
PubMed2000

Comparative genomics of the eukaryotes.

A comparative analysis of the genomes of Drosophila melanogaster, Caenorhabditis elegans, and Saccharomyces cerevisiae-and the proteins they are predicted to encode-was undertaken in the context of cellular, developmental, and evolutionary processes. The nonredundant protein sets of flies and worms are similar in size and are only twice that of yeast, but different gene families are expanded in each genome, and the multidomain proteins and signaling pathways of the fly and worm are far more complex than those of yeast. The fly has orthologs to 177 of the 289 human disease genes examined and provides the foundation for rapid analysis of some of the basic processes involved in human disease.

Animals↗
PubMed2000

Effects of metabolic fragments of [Arg(8)]-vasopressin on nerve growth in cultured hippocampal neurons.

The effects of metabolic fragments of [Arg(8)]-vasopressin (AVP), [pGlu(4), Cyt(6)]AVP (AVP(4-9)), and desglycinamide-[pGlu(4), Cyt(6)]AVP (AVP(4-8)) on the growth of hippocampal neurons in culture were investigated in comparison with those of AVP. AVP(4-9) caused a significant increase in filopodial length following 96 h of exposure at concentrations higher than 300 nM. AVP(4-9) was more potent than AVP. AVP(4-8) also induced an increase in filopodial length, but this effect was less than that of AVP. The selective V(1) agonist [Phe(2), Ile(3), Orn(8)]-vasopressin caused a significant increase in filopodial length, whereas the selective V(2) agonist [deamino-Cys(1), D-Arg(8)]-vasopressin showed no such effect. OPC-21268, a vasopressin V(1) antagonist, blocked AVP and AVP fragment-induced increases in filopodial length. However, the V(2) antagonist OPC-31260 showed no such effect. A23187, a representative Ca ionophore, also increased filopodial length, and the A23187-induced increase in filopodial length was potentiated by AVP and AVP fragments. These results indicated that AVP(4-9) and AVP(4-8) increased filopodial length in cultured hippocampal neurons by activating V(1) receptors. Both phenomena induced by AVP(4-9) and AVP(4-8) were associated with intracellular calcium mobilization.

Animals↗
PubMed2000

Synthesis and study of C(3)-symmetric hydropyran cyclooligolides with oriented aryl and alcohol appendages at 10 A spacing.

Modular syntheses of C(3)-symmetric macrocycles with pendant aryl and hydroxymethyl groups are described. These functional groups, amenable to further elaboration, were installed early in each synthesis and carried through an iterative sequence of module coupling and macrolactonization. Association constants for macrolides 1a-c with alkali metal cation guests were determined, and sandwich-type complexes with Ba(2+) were confirmed for these macrocycles based on (1)H NMR studies, including Job plots. X-ray crystallographic data for macrolides 1a and 1c were obtained and are discussed in detail. These data provide support that the macrolides are structurally well-defined and preorganized for binding the potassium cation. Preparation of the tris(bromoacetylated) macrotriolide 43 exemplifies a functionalized platform suitable for elaboration with peptide or carbohydrate residues.

Alcohols↗
PubMed2000

Structure of the RXR-RAR DNA-binding complex on the retinoic acid response element DR1.

The 9-cis retinoic acid receptor (retinoid X receptor, RXR) forms heterodimers with the all-trans retinoic acid receptor (RAR) and other nuclear receptors on DNA regulatory sites composed of tandem binding elements. We describe the 1.70 A resolution structure of the ternary complex of RXR and RAR DNA-binding regions in complex with the retinoic acid response element DR1. The receptors recognize identical half-sites through extensive base-specific contacts; however, RXR binds exclusively to the 3' site to form an asymmetric complex with the reverse polarity of other RXR heterodimers. The subunits associate in a strictly DNA-dependent manner using the T-box of RXR and the Zn-II region of RAR, both of which are reshaped in forming the complex. The protein-DNA contacts, the dimerization interface and the DNA curvature in the RXR-RAR complex are distinct from those of the RXR homodimer, which also binds DR1. Together, these structures illustrate how the nuclear receptor superfamily exploits conformational flexibility and locally induced structures to generate combinatorial transcription factors.

Amino Acid Sequence↗
PubMed2000

A second tonB gene in Pseudomonas aeruginosa is linked to the exbB and exbD genes.

The exbBD genes of Pseudomonas aeruginosa PAO were cloned by complementation of the growth defect of an Escherichia coli exbB tolQ double mutant on iron-restricted medium. Nucleotide sequence analysis confirmed that these genes are contiguous and preceded by a second tonB gene in this organism, which we have designated tonB2. lacZ promoter fusions confirmed that expression of the tonB2-exbB-exbD genes is increased under conditions of iron limitation. Deletions within any of these genes, in contrast to deletions in the first tonB gene, tonB1, did not adversely affect growth on iron-restricted medium. On the other hand, tonB1 tonB2 double mutants were more compromised as regards growth in an iron-restricted medium than a tonB1 deletion, indicating that TonB2 could partially replace TonB1 in its role in iron acquisition. TonB1 but not TonB2 deletion strains were also compromised as regards the utilization of hemin or hemoglobin as sole iron sources, indicating that heme transport requires TonB1.

Bacterial Proteins↗
PubMed2000

Structural basis of RXR-DNA interactions.

The 9-cis retinoic acid receptor, RXR, binds DNA effectively as a homodimer or as a heterodimer with other nuclear receptors. The DNA-binding sites for these RXR complexes are direct repeats of a consensus sequence separated by one to five base-pairs of intervening space. Here, we report the 2.1 A crystal structure of the RXR-DNA-binding domain as a homodimer in complex with its idealized direct repeat DNA target. The structure shows how a gene-regulatory site can induce conformational changes in a transcription factor that promote homo-cooperative assembly. Specifically, an alpha-helix in the T-box is disrupted to allow efficient DNA-binding and subunit dimerization. RXR displays a relaxed mode of sequence recognition, interacting with only three base-pairs in each hexameric half-site. The structure illustrates how site selection is achieved in this large eukaryotic transcription factor family through discrete protein-protein interactions and the use of tandem DNA binding sites with characteristic spacings.

Allosteric Regulation↗