Search PubMed⌕ Search

Biomedical subjects

Q Zhang

Publications and source records attributed to Q Zhang.

At least 811 records · Page 45Linked to original sources
PubMed1995

[The relationship between the phenotype of tumor infiltrating cells and the prognosis in laryngeal cancer].

By using the method of immunohistochemical avidin-biotin-peroxidase complex (ABC), toluidine blue and HE staining, the infiltrated grade and dispersed feature about the T-lymphocytes, B-Lymphocytes, macrophages, langerhans cells, mast cells and eosinophils of peritumoral stroma were investigated in 82 cases with laryngeal carcinoma. A stepwise logistic regression analysis of eight clinicopathologic variables and the density of six kinds of tumor infiltrating cells in the study were analyzed with the clinical outcome of the patients. The results showed that T-lymphocytes was the major infiltrated cells. The other cells such as macrophages, langerhans cells, mast cells and eosinophils were also to be found in local infiltration, but the B-cell was scanty. All these cells except B-cell had significant effect on the 5-year survival rate of the patients. By the multivariate analysis, the peritumoral infiltrated eosinophils was the most influential variable affecting clinical outcome, followed by the peritumoral infiltrated T-lymphocytes and the tumor histologic grade. We concluded that tumor infiltrating cells played a critical role in local host antitumor immune reaction.

Adult↗
PubMed1995

Immunoglobulin depositions in peripheral nerves in polymyositis.

An immunocytochemical study was performed in 6 peripheral nerve specimens from 6 cases of polymyositis. The results revealed that depositions of IgG, IgM, IgA and C3 were found in the epineurium, perineurium and the walls of capillaries. These findings demonstrated that depositions of immunoglobulins and the complement-mediated immunoreaction may play an important role in pathogenesis of polymyositis with peripheral nerve involvements.

Adult↗
PubMed1995

[The proliferative activity of laryngeal carcinoma and its relationship to histological malignancy and prognosis].

Cellular proliferation indices such as proliferating cell nuclear antigen (PCNA), DNA content index and mitotic figure counts (MFC) were evaluated in 70 cases of laryngeal squamous cell carcinoma. The results showed that there were strong correlations between these indices and histological grading of the carcinoma (P < 0.01, P < 0.01, P < 0.05). Both PCNA index and MFC were related to the five-year survival rate (P < 0.01). The PCNA labelling index was corresponded with both DNA index and MFC (r = 0.61, P < 0.001; r = 0.76, P < 0.001). Our data suggest that cellular proliferation of laryngeal carcinoma can be reliably assessed with three different methods and these indices can be used as the predictor of tumor malignancy and prognosis.

Adult↗
PubMed1995

[Comparison of MIVQUE and REML with Monte Carlo simulation].

A comparison of two methods for estimation of variance component, MIVQUE and REML, was carried out on four data sets with Monte Carlo simulation. The model used was the sire model containing herd-year-season(HYS) effect (fixed), sire group effect(fixed) and sire effect(random), which is widely used in dairy cattle breeding. The largest data set consisted of 12847 records with 47 sires and 778 HYSs, which is corresponding to the milk yield data available currently in Beijing area. The smallest data set comprised 200 records with 148 HYSs and 20 sires. The criterion for the comparison were the bias and variance, either theoretical or empirical based on 1000 repeated simulations, of the estimates. The results show that for the larger data sets the two methods are little different from each other: Bias < 1% of the true values, correlation approximately 1, and variance (MIVQUE) approximately variance (REML). For the smaller data sets the MIVQUE was significantly better than REML. It was also shown that for REML the sample size like the first data set can satisfy its large sample properties of asymptotical unbiasedness and efficiency.

Animals↗
PubMed1995

Mutation detection and genetic counseling in retinoblastoma using heteroduplex analysis.

Gene diagnosis is essential for confident presymptomatic prediction, genetic counseling, and early management of hereditary retinoblastoma. In screening the leukocyte DNA of three patients with bilateral retinoblastoma for RB1-gene heterozygous germline mutations, we identified mutations involving exon 3 or 18 of the RB1 gene by using heteroduplex analysis and sequencing. In one case the mutation was a 2 bp GT deletion resulting in the loss of the exon 18 splicing-donor; another mutation was a G-to-T transversion at codon 580 in exon 18, which converts Arg to a stop codon. The third mutation involved in 1 bp deletion at codon 96 in exon 3, which leads to a premature stop codon at codon 110. We used information from this heteroduplex technique for genetic counseling and presymptomatic prediction. A newborn was identified as normal, using gene diagnosis; his 15-month follow-up confirmed our prediction.

Base Sequence↗
PubMed1994

Galanin antisense oligonucleotides reduce galanin levels in dorsal root ganglia and induce autotomy in rats after axotomy.

Antisense (AS) oligonucleotides (ONs) to galanin (GAL) were applied to the proximal end of a transected sciatic nerve, allowing their cellular uptake and transport into injured axons. GAL expression in dorsal root ganglia and self-mutilation behavior (autotomy) were then studied. AS-ONs with phosphorothioate or allyl modifications significantly suppressed the axotomy-induced increase in GAL levels, as demonstrated by immunohistochemistry and exaggerated autotomy behavior, whereas no significant effect on GAL mRNA levels could be demonstrated with in situ hybridization. Allyl-ONs were more effective than phosphorothioate-ONs. An AS-ON with three base mismatches did not induce any of the above effects. These results support the view that the inhibition of axotomy-induced GAL up-regulation is related to autotomy.

Animals↗
PubMed1994

Comparative analysis of microsatellite DNA polymorphism in landraces and cultivars of rice.

Genetic polymorphisms of ten microsatellite DNA loci were examined among 238 accessions of landraces and cultivars that represent a significant portion of the distribution range for both indica and japonica groups of cultivated rice. In all, 93 alleles were identified with these ten markers. The number of alleles varied from a low of 3 or 4 at each of four loci, to an intermediate value of 9-14 at five loci, and to an extraordinarily high 25 at one locus. The numbers of alleles per locus are much larger than those detected using other types of markers. The number of alleles detected at a locus is significantly correlated with the number of simple sequence repeats in the targeted microsatellite DNA. Indica rice has about 14% more alleles than japonica rice, and such allele number differences are more pronounced in landraces than in cultivars. The indica-japonica differentiation component accounted for about 10% of the diversity in the total sample, and twice as much differentiation was detected in cultivars as in landraces. About two-thirds as many alleles were observed in cultivars as in landraces; another two-thirds of the alleles in the cultivar group were found in modern elite cultivars or parents of hybrid rice. The majority of the simple sequence repeat (SSR) alleles that were present in high or intermediate frequencies in landraces ultimately survived into modern elite cultivars and hybrids. The greater resolving power and the efficient production of massive amounts of SSR data may be particularly useful for germplasm assessment and evolutionary studies of crop plants.

Alleles↗
PubMed1994

Phosphatase inhibitors block in vivo binding of peptides to class I major histocompatibility complex molecules.

Class I major histocompatibility complex (MHC) molecules are heterotrimers of heavy chains, beta 2-microglobulin, and 8-10 amino acid-long peptides. Assembly of class I MHC molecules into complexes which are stable and can be transported to the cell surface occurs soon after insertion of individual subunits into the endoplasmic reticulum (ER). To identify subcellular compartments required for class I MHC assembly, we studied class I biosynthesis in human cell lines treated with several inhibitors of intracellular transport. We found that HLA-B701 molecules do not assemble in CIR transfectants in which a block in protein transport from the ER is established by treatment with phosphatase inhibitors. In contrast, stable HLA-B701 complexes form in cells in which the ER becomes mixed with the Golgi after treatment with brefeldin A. Neither treatment impaired binding of HLA-B701 to the ER-resident protein calnexin, and unassembled heavy chains in phosphatase-inhibited cells showed prolonged association with calnexin. In addition, the mouse class I molecule H-2Db, which binds beta 2-microglobulin in human T2 cells in the absence of transporter of antigenic peptides, formed complexes in CIR cell transfectants treated with phosphatase inhibitors. Taken together, these data demonstrate that phosphatase inhibitors do not prevent assembly of class I heavy chain beta 2-microglobulin dimers, but instead interfere with peptide loading. These results are consistent with the possibility that class I MHC molecules are transported from their initial site of insertion into the rough ER before binding peptides, or alternatively that peptide loading mediated by transporter of antigenic peptides is blocked by phosphatase inhibitors.

Animals↗
PubMed1994

The modification of hemoglobin by a long crosslinking reagent: bis(3,5-dibromosalicyl) sebacate.

Bis(3,5-dibromosalicyl) sebacate is a bifunctional protein crosslinking reagent. It reacts with oxy form of human hemoglobin A to produce a crosslinked hemoglobin between two beta chains in the 2,3-bisphosphoglycerate binding cleft, decreasing the oxygen affinity. The oxygen binding curve of crosslinked hemoglobin had a P50 of 18.5 mmHg compared to a P50 of 11.0 mmHg for native hemoglobin and remains highly cooperative, n = 2.2. Crosslinking hemoglobin between the two beta chains also results in a 12.5 degrees C increase in the thermal denaturation temperature. The crosslinked hemoglobin is oxidized more rapidly to methemoglobin. Its autoxidation rate in 0.01 M MOPS, pH 7.4, at 37 degrees C was 1.4 times as fast as that of Hb A.

2,3-Diphosphoglycerate↗
PubMed1994

Using bulked extremes and recessive class to map genes for photoperiod-sensitive genic male sterility in rice.

Photoperiod-sensitive genic male sterile (PS-GMS) rice has a number of desirable characteristics for hybrid rice production. In this study we made use of a published rice genetic linkage map to determine the locations of PSGMS genes and we have characterized the effects of these genes on sterility by using molecular markers. A two-step approach was designed for mapping the genes: (i) identifying possible PSGMS gene-containing chromosome regions with bulked DNA from extreme fertile and extreme sterile plants of a very large F2 population and (ii) determining the map locations of the genes in extreme sterile individuals. We show that this mapping method is much more cost effective and statistically efficient than using a random sample of an F2 population. We identified two chromosomal regions each containing a PSGMS locus, one designated pms1 on chromosome 7 and one designated pms2 on chromosome 3. The existence of these two loci was confirmed by a large sample assay and with data on rationing progenies of the F2 plants. A marker-based analysis shows that the effect of pms1 is 2-3 times larger than that of pms2 and that dominance is almost complete at both loci. Implications in the breeding of PSGMS rice lines are discussed.

Chromosome Mapping↗
PubMed1994

Expression and characterization of p27, the catalytic subunit of the apolipoprotein B mRNA editing enzyme.

An RNA editing mechanism converts C to U at nucleotide 6666 in apolipoprotein B (apoB) mRNA. The catalytic subunit of the editing enzyme, p27, was recently cloned. When expressed in Xenopus oocytes, p27 required other proteins to edit apoB mRNA in vitro (Teng, B., Burant, C. F., and Davidson, N. O. (1993) Science 260, 1816-1819). In this study, we expressed p27 in McArdle 7777 cells, which edit apoB mRNA with low efficiency. The levels of editing enzyme increased 10-fold, and editing of the endogenous apoB mRNA increased 2-fold in p27-transfected cells. These results demonstrate that p27 is involved in editing in mammalian cells. p27 was also expressed in COS cells, which do not synthesize apoB and lack editing activity. Extracts from p27-transfected cells acquired the ability to edit apoB mRNA only when extracts from other tissues were added. This reconstituted enzyme had the same sequence specificity as the native enzyme. The activity that complemented p27 function was detected in baboon liver and in tissues that do not synthesize apoB, including kidney and testis. The COS expression system was used to analyze the structure and function of p27, which contains a putative zinc finger (His61, Cys93, and Cys96) similar to other cytidine deaminases. Site-directed mutagenesis of His61 to Arg, Pro92 to Leu, or Cys96 to Ser abolished p27 activity. The zinc finger in p27 may be required for catalysis, protein-protein interactions, or binding to apoB mRNA.

APOBEC-1 Deaminase↗
PubMed1994

Extraordinarily polymorphic microsatellite DNA in barley: species diversity, chromosomal locations, and population dynamics.

This study was undertaken to assess the extent of genetic variation in barley simple sequence repeats (SSRs) and to study the evolutionary dynamics of SSR alleles. SSR polymorphisms were resolved by the polymerase chain reaction with four pairs of primers. In total, 71 variants were observed in a sample of 207 accessions of wild and cultivated barley. Analyses of wheat-barley addition lines and barley doubled haploids identified these variants (alleles) with four loci, each located on a different chromosome. The numbers of alleles detected at a locus corresponded to the number of nucleotide repeats in the microsatellite sequences. The numbers of alleles at two loci were 28 and 37; to our knowledge these are the largest numbers of alleles for single Mendelian loci reported in plants. Three alleles were resolved by each of the other two loci. Allelic diversity was greater in wild than in cultivated barley and surveys of two generations (F8 and F53) of Composite Cross II, an experimental population of cultivated barley, showed that few of the alleles present in the 28 parents survived into generation F53, whereas some infrequent alleles reached high frequencies. Such changes in frequency indicate that the chromosomal segments marked by the SSR alleles are under the influence of natural selection. The SSR variants allow specific DNA sequences to be followed through generations. Thus, the great resolving power of SSR assays may provide clues regarding the precise targets of natural and man-directed selection.

Alleles↗
PubMed1994

Heme protein dynamics studied by phosphorescence of an external phosphorescent probe molecule.

The rate constant for quenching, kq, of the phosphorescence of 6-bromo-2-naphthyl sulfate (BNS) by cytochromes c, cytochrome c peroxidase, catalase, and myoglobin has been measured as a function of temperature and solvent viscosity. In aqueous solution at pH 7.0 for cytochromes c and myoglobin the value of kq is nearly equal to the rate constant for diffusional intermolecular contact, which is estimated from the value of kq for microperoxidase-11. For cytochrome c peroxidase and catalase kq is at least 350 times smaller than the rate of diffusional quenching, which shows that quenching of BNS phosphorescence occurs predominantly over the short distance between donor and acceptor. The mechanism for cytochrome c and myoglobin is found not to involve static quenching, deep penetration of BNS into the globin, or unfolding of the protein to allow contact between heme and BNS. It is concluded that quenching occurs by interaction of BNS with the exposed heme edge and by surface insertion of BNS into the protein to a depth sufficient for quenching by the unexposed heme. The effect of rapid-diffusional enhancement on kq is small. From a comparison of the results for the heme proteins, a model emerges that describes cytochrome c and myoglobin as having dynamic surfaces. Sufficient fluctuations persist to allow penetration of polyatomic probe molecules into the protein matrix, but the dynamics and/or interior microenvironment acts to increase resistance with increasing depth of penetration.

Animals↗
PubMed1994

An evolutionarily conserved palindrome in the Drosophila Gld promoter directs tissue-specific expression.

A conserved palindromic sequence (Gpal) in the promoter region of the Drosophila Gld directs expression of a heterologous reporter gene in transgenic flies to the anterior spiracular glands of third instar larvae and to the ejaculatory bulb of adult males. The Gld gene is normally expressed at high levels in the anterior spiracular glands but is not expressed in the ejaculatory bulb of Drosophila melanogaster. However, Gld promoters from other Drosophila species contain the Gpal element and express glucose dehydrogenase (GLD) in the adult male ejaculatory bulb. A gene fusion composed of the D. melanogaster Gld promoter and the lacZ gene is expressed in the anterior spiracular glands of transgenic larvae. Mutations of the Gpal sequence element in this gene fusion block expression of beta-galactosidase in the anterior spiracular gland. Together these experiments demonstrate that Gpal is necessary and sufficient for tissue-specific expression in the anterior spiracular glands. Based upon the tissue distribution and function of GLD, it is speculated that expression of GLD in the anterior spiracular glands represents the ancestral state and that GLD expression in other tissues arose as a fortuitous consequence of a shared combinatorial regulatory network.

Animals↗