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Biomedical subjects

T Xie

Publications and source records attributed to T Xie.

At least 73 records · Page 4Linked to original sources
PubMed1996

[Rapid genotyping for HLA-DR by PCR-amplification with sequence-specific primers and clinical practice].

Genotyping for HLA-DR alleles by polymerase chain reaction with sequence-specific primers (PCR-SSP) was first typed in 112 individuals of donor-recipients of cadaveric transplantation and 9 cell lines DNA. Twenty separate PCR reactions were performed per sample. The amplification was accomplished by 34 cycles consisting of denaturation at 94 degrees C for 30 sec, annealing at 60 degrees C for 50 sec and extension at 72 degrees C for 40 sec. HLA-DR alleles could be accurately distinguished. The overall time of genotyping was only 5 hours. The specificity of matching was determined against a panel of standard DNA, analysis with restriction endonucleases, and Southern hybridization using DIG oligonucleotide 3'- end labeling probes. The specificity and reproducibility were 100%. No false positive or false negative typing results were obtained. These showed genotyping by PCR-SSP was a rapid and accurate matching technique, suited for clinical practice.

Alleles↗
PubMed1995

ARE- and TRE-mediated regulation of gene expression. Response to xenobiotics and antioxidants.

Antioxidant response elements (AREs) containing 12-O-tetradecanoylphorbol-13-acetate response element (TRE) (perfect AP1) and TRE-like (imperfect AP1) elements mediate high basal transcription of the NAD(P)H:quinone oxidoreductase1 (NQO1) and glutathione S-transferase Ya genes in tumor cells and its induction in response to xenobiotics and antioxidants. Mutations in the human NQO1 gene ARE (hARE) revealed the requirement for two TRE or TRE-like elements arranged in inverse orientation at the interval of three base pairs and a GC box for optimal expression and beta-naphthoflavone induction of the NQO1 gene. A single TRE element from the human collagenase gene failed to respond to beta-naphthoflavone. These results demonstrate that ARE (2 x TRE or TRE-like elements)-containing detoxifying enzyme genes and not genes that contain 1 x TRE are responsive to xenobiotics and antioxidants. Bandshift assays showed shifting of a complex of more or less similar mobility with hARE and TRE that could be competed by each other. Mutations in the 3'-TRE of the NQO1 gene hARE eliminated binding of nuclear proteins to the hARE and resulted in the loss of basal and induced expression, indicating that 3'-TRE is the most important element within the hARE. 5'-TRE-like element within the NQO1 gene hARE is required for xenobiotic response but may not bind to the nuclear proteins by itself. The GC box located immediately following the 3'-TRE is required for optimal expression and induction of the NQO1 gene. The comparison of AREs from several different genes indicated the requirement for specific arrangement and spacing of two TRE and TRE-like elements within the AREs.

Antioxidants↗
PubMed1995

The tolkin gene is a tolloid/BMP-1 homologue that is essential for Drosophila development.

The Drosophila decapentaplegic (dpp) gene, a member of the transforming growth factor beta superfamily of growth factors, is critical for specification of the embryonic dorsal-ventral axis, for proper formation of the midgut, and for formation of Drosophila adult structures. The Drosophila tolloid gene has been shown to genetically interact with dpp. The genetic interactions between tolloid and dpp suggests a model in which the tolloid protein participates in a complex containing the DPP ligand, its protease serving to activate DPP, either directly or indirectly. We report here the identification and cloning of another Drosophila member of the tolloid/bone morphogenic protein (BMP) 1 family, tolkin, which is located 700 bp 5' to tolloid. Its overall structure is like tolloid, with an N-terminal metalloprotease domain, five complement subcomponents C1r/C1s, Uegf, and Bmp1 (CUB) repeats and two epidermal growth factor (EGF) repeats. Its expression pattern overlaps that of tolloid and dpp in early embryos and diverges in later stages. In larval tissues, both tolloid and tolkin are expressed uniformly in the imaginal disks. In the brain, both tolloid and tolkin are expressed in the outer proliferation center, whereas tolkin has another stripe of expression near the outer proliferation center. Analysis of lethal mutations in tolkin indicate it is vital during larval and pupal stages. Analysis of its mutant phenotypes and expression patterns suggests that its functions may be mostly independent of tolloid and dpp.

Amino Acid Sequence↗
PubMed1995

[Liver-protecting and alanine aminotransferase lowering actions of hongning gantai].

Hongning Gantai has a remarkable counteraction on the elevation of ALT activity of mice and rats induced by chemical damages with CCl4 and D-Gal. It can decrease the BSP-retention. The result of pathologic examination indicates that Hongning Gantai can alleviate liver damages of mice and rats and thus has liver-protecting and ALT-lowering actions.

Alanine Transaminase↗
PubMed1995

[Detection of carcinogen in source drinking water in stomach cancer prevalent areas of Zanhuang county].

Benzo(a) pyrene, aflatoxin, sterigmatocystin and six kinds of nitrosamine and their precursors (secondary amine) in 36 specimens of source drinking water collected from stomach cancer prevalent areas of Zanhuang County during the autumn and spring periods were determined quantitatively with high performance liquid chromatography. Results showed drinking water for local residents was significantly contaminated with benzo(a) pyrene, with an average of 0.0148 microgram/L and the highest one of 0.0305 microgram/L, and especially in the autumn, simultaneous contamination with nitrosodimethylamine, nitrosodiethylamine, and nitrosodipropylamine could be found, with proportions of 38.5%, 76.9% and 76.9%, respectively. Aflatoxin B1, and G1 could also be found in drinking water in the autumn, but no sterigmatocystin could be detected.

Aflatoxins↗
PubMed1995

Comparison of proliferating cell nuclear antigen versus the more standard measures of rectal mucosal proliferation rates in subjects with a history of colorectal cancer and normal age-matched controls.

Measurement of proliferation rates by the more standard in vitro uptake techniques of [3H]thymidine and 5'-bromo-2'-deoxyuridine (BrdUrd) labeling indices (LIs) were compared to proliferating cell nuclear antigen (PCNA) in rectal mucosal biopsies from 16 subjects with resected colorectal cancer and 14 normal age-matched controls. Correlation coefficients for BrdUrd versus PCNA, [3H]thymidine versus PCNA, and BrdUrd versus [3H]thymidine were 0.691, 0.876, and 0.770, respectively. No significant differences (P > 0.05) were detected in total mean LIs between the LI methods for the normal group. In contrast, total PCNA LIs were found to be significantly different in the resected cancer patients when compared to either BrdUrd (P = 0.005) or [3H]thymidine (P < 0.001). A significant difference (P = 0.010) in total PCNA LI but not in total [3H]thymidine or BrdUrd LIs was also observed between normal controls and resected colorectal cancer subjects. Compartmental analysis of the cancer group versus the normals showed a significant difference in compartments 1 and 3 for PCNA LIs only. The reproducibility of two PCNA LI counts was excellent (r = 0.9). In addition, the reliability of mean LIs were > 0.8 with the exception of [3H]thymidine in the normal group (0.7). These study results demonstrate that PCNA LIs in human rectal mucosal biopsies are correlated highly with other more commonly used cellular proliferation measurements; however, PCNA LIs were found to be significantly higher than the other two methods in the resected colorectal cancer subjects.

Adult↗
PubMed1995

[Clinical and experimental study on oral liquor night-cough tranquiller in treating infantile cough].

Oral Liquor of Night-Cough Tranquiller (NCT) was used in treating infantile cough and 128 patients have been treated. The result revealed that the total effective rate was 95.3%. In comparing with other group of patients treated with the common cold cough syrup and Caps. cephalexini, the latter has a clinical effective rate of 81.0%. A significant difference existed between the above-mentioned two groups (P < 0.05). According to the animal experiment, the NCT has some outstanding pharmacologic functions such as anti-tussive function, phlegm reducing and sedation, etc. While the LD50 of NCT has not been detected which indicated that this preparation has negligible side effect.

Animals↗
PubMed1995

Antisense oligodeoxyribonucleotide down-regulation of bcl-2 gene expression inhibits growth of the low-grade non-Hodgkin's lymphoma cell line WSU-FSCCL.

The BCL-2 gene product is involved in preventing apoptosis. The t(14,18) chromosomal translocation, which results in a fusion messenger RNA containing the entire coding region of BCL-2 and a portion of the immunoglobulin heavy chain gene, is commonly found in follicular lymphoma and appears to play a role in lymphomagenesis by inhibiting cell death. We tested the hypothesis that downregulation of BCL-2 would decrease accumulation of follicular lymphoma cells by treating the t(14,18)-carrying follicular lymphoma cell line WSU-FSCCL in vitro with antisense oligodeoxyribonucleotides (ODNs) directed against BCL-2. We found dose-dependent, sequence-specific inhibition of cell accumulation by an antisense unmodified ODN directed at codons 2 to 7, which downregulated BCL-2 protein levels. This effect was near maximal at an ODN concentration of 40 micrograms/mL (6.9 mumol/L), with minimal toxicity by control sense, reverse, and mutated antisense ODN at the same concentration. The pre-B leukemia cell line REH showed no sequence-specific growth inhibition by the antisense ODN at these concentrations, and BCL-2 protein levels were not altered. These data suggest that WSU-FSCCL may be useful in a murine model to optimize antisense ODN for potential therapeutic utility.

Base Sequence↗
PubMed1994

The Drosophila saxophone gene: a serine-threonine kinase receptor of the TGF-beta superfamily.

The Drosophila decapentaplegic (dpp) gene encodes a transforming growth factor-beta (TGF-beta)-like protein that plays a key role in several aspects of development. Transduction of the DPP signal was investigated by cloning of serine-threonine kinase transmembrane receptors from Drosophila because this type of receptor is specific for the TGF-beta-like ligands. Here evidence is provided demonstrating that the Drosophila saxophone (sax) gene, a previously identified female sterile locus, encodes a TGF-beta-like type I receptor. Embryos from sax mothers and dpp embryos exhibit similar mutant phenotypes during early gastrulation, and these two loci exhibit genetic interactions, which suggest that they are utilized in the same pathway. These data suggest that sax encodes a receptor for dpp.

Amino Acid Sequence↗
PubMed1994

Mutational analysis of the Drosophila tolloid gene, a human BMP-1 homolog.

Seven zygotically active genes have been identified in Drosophila that determine the fate of dorsal cells in the developing embryo. decapentaplegic (dpp), a member of the transforming growth factor-beta (TGF-beta) family, appears to play the central role in dorsal ectoderm formation, as mutations in this gene confer the most severe mutant phenotype of this group of genes. dpp's activity is modulated by tolloid, which also has a role in the determination of dorsal cell fate. tolloid encodes a protein that contains a metalloprotease domain and regulatory domains consisting of two EGF motifs and five C1r/s repeats. We have generated several mutant tolloid alleles and have examined their interaction with a graded set of dpp point alleles. Some tolloid alleles act as dominant enhancers of dpp in a trans heterozygote, and are therefore antimorphic alleles. However, a tolloid deficiency shows no such genetic interaction. To characterize the nature of the tolloid mutations, we have sequenced eighteen tolloid alleles. We find that five of the seven alleles that act as dominant enhancers of dpp are missense mutations in the protease domain. We also find that most tolloid alleles that do not interact with dpp are missense mutations in the C-terminal EGF and C1r/s repeats, or encode truncated proteins that delete these repeats. Based on these data, we propose a model in which the tolloid protein functions by forming a complex containing DPP via protein-interacting EGF and C1r/s domains, and that the protease activity of TOLLOID is necessary, either directly or indirectly, for the activation of the DPP complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1994

Anomalous glutamate/alkali cation symport in larval Manduca sexta midgut.

Rapid filtration assays were used to characterize glutamate/cation uptake in brush-border membrane vesicles from the larval midgut of the lepidopteran Manduca sexta. At pH 10.5, which is close to the physiological pH in the midgut of M. sexta, an inwardly directed K+ gradient stimulated glutamate uptake, suggesting that glutamate was symported. Gradients of Na+ or Li+ were less effective. Neither Rb+ nor Cs+ stimulated glutamate uptake. Anion-specificity was less pronounced: the accumulation maximum was only slightly higher with thiocyanate (SCN-) than with Cl-, although initial uptake was noticeably faster with thiocyanate. A distinct set of amino acids that would cis-inhibit or trans-elicit glutamate uptake was not found. Even L-glutamate itself did not elicit accumulations of labeled glutamate. Taken together, these results suggest that a glutamate-specific symporter may not be present. Moreover, because glutamate symport was found to be electroneutral in vitro whereas amino acid uptake is electrophoretic in vivo, we infer that symport with K+ may not be an important mechanism of glutamate translocation by M. sexta midgut.

Animals↗
PubMed1994

Substrate structure and amino acid/K+ symport in brush-border membrane vesicles from larval Manduca sexta midgut.

The effects of amino acid sidechain length, substituent position and c chirality on amino acid/K+ symport have been examined in rapid filtration experiments on brush-border membrane vesicles prepared from larval Manduca sexta midgut. Cis-inhibition and trans-stimulation protocols were used to examine the effects of amino acid analogs on the uptake of alanine, phenylalanine, leucine and lysine, which are cotransported with K+ by a zwitterionic symporter at the high pH characteristic of the midgut in vivo. The symporter was found to translocate both L- and D-stereoisomers of alanine, leucine and lysine, but only the L-form of phenylalanine. Alterations to substrate structure that leave the charge distribution unchanged do not affect symport. Thus, moving the methyl group from C-3 to C-5 in the sequence isoleucine, leucine and norleucine has no effect on their ability to inhibit leucine symport. Increasing sidechain length among alanine homologs has little effect on their ability to inhibit alanine uptake, but increasing the sidechain length of lysine homologs from 1 to 3 methylene groups enhances cis-inhibition and trans-stimulation of lysine symport. The substantial difference in molecular charge distribution among aminobutanoic acid isomers has a large impact on alanine symport with only alpha- (or 2-) aminobutanoic acid functioning as an alanine analog. Only those changes in substrate structure that are coupled to the molecular charge distribution seem to affect symport. The tolerance of the symporter may reflect a balance mandated by the conflicting demands of selectivity and throughput.

Amino Acids↗
PubMed1994

NAD(P)H:quinone oxidoreductase1 (DT-diaphorase): expression, regulation, and role in cancer.

NAD(P)H:quinone oxidoreductase1 (DT-diaphorase or NQO1) is a flavoprotein that promotes obligatory two-electron reduction of quinones, preventing their participation in redox cycling, oxidative stress, and neoplasia. NQO1 is ubiquitously expressed. However, a large amount of variation in NQO1 gene expression was noticed among various human tissues. NQO1 gene is upregulated in livers of hepatocarcinoma patients, and its expression is induced in response to a variety of compounds, including planar aromatic hydrocarbons, phenolic antioxidants/chemoprotectors, tumor promoters, and hydrogen peroxide. Deletion mutagenesis in the NQO1 gene promoter identified several cis-elements including antioxidant response element (ARE), xenobiotic response element, and AP2 element, which regulate the expression and induction of the NQO1 gene. Among these DNA elements, ARE is the most important cis-element required for high basal expression of the NQO1 gene in tumor tissues, as compared to the normal tissues of the same origin, and for its induction in response to xenobiotics and antioxidants. Nucleotide sequence analysis of the ARE indicated presence of three AP1/AP1-like elements and a GCA box. Mutational analysis indicated a requirement of two AP1/AP1-like elements arranged as inverse repeats at the interval of three base pairs for the ARE activity. The GCA box in the ARE was required for optimum basal and induced expression. ARE is a novel cis-element because a single AP1/AP1-like element did not stimulate gene expression in response to xenobiotics and antioxidants. Band shift and supershift assays identified Jun, Fos, and novel proteins in the hARE-nuclear protein complexes that mediate regulation of the NQO1 gene expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Physical mapping of buzura suppressaria nuclear polyhedrosis virus genome.

A physical map of the genome of buzura suppressaria singly-enveloped nuclear polyhedrosis virus (BsSNPV) was determined using six restriction endonucleases (RE), singly or in pairs, and Southern hybridizations of cloned or gel-purified DNA fragments. The maps of the genomes of BsSNPV and autographa californica multiply-enveloped nuclear polyhedrosis virus (AcMNPV) were different.

Animals↗
PubMed1993

Anti-CD3 and -CD4 monoclonal antibody in the treatment of steroid-resistant renal allograft rejection.

Between November 1987 and October 1991, 40 consecutive cadaveric renal recipients immunosuppressed with cyclosporine (CsA) who developed renal allograft rejection were treated with domestically prepared muromonab CD3 (Wu 338) and CD4 (Wu167). CD3 and CD4 monoclonal antibodies (McAb) as rescue treatment (n = 34) successfully reversed 29 cases of (85.3%) intractable renal allograft rejection (steroid resistant rejection 32 and anti-human thymocyte globulin [AHTG] resistant rejection 2) and completely reversed 4 cases of acute renal rejection episodes CD3 McAb as first-line treatment (n = 4). Two cases of chronic rejection failed in the treatment of McAb. Rejection episodes were reversed from 4 to 11 days (mean 6 days). Combined use of CD3 and CD4 McAb seemed to yield better results. Peripheral blood T lymphocyte subsets showed that CD3+, CD4+ and CD8+ decreased significantly after the treatment of McAb. No severe side-effects were observed in the treatment of McAb. The McAb could be administered safely. Pulmonary infection rate was 15%. The yearly graft survival rate was increased significantly (87.8% vs 80.0%).

Adult↗
PubMed1993

Treatment of chronic allograft rejection.

Chronic renal allograft rejection at present the most important factor affecting long-term graft survival, and effective therapeutic method is still lacking. This article reports 43 cases of chronic renal rejection treated from January 1989 to April 1992. Effective result was obtained in 27 cases (62.8%). The authors believe that increasing dosage of the immunosuppressants is an effective method for the management of chronic renal rejection and the earlier the treatment is given the better the results would be. The selection and the regulation of the dosage of the immunosuppressants should be determined according to the individual situation.

Adolescent↗