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Biomedical subjects

Y Lu

Publications and source records attributed to Y Lu.

At least 667 records · Page 37Linked to original sources
PubMed1997

[Fluorometric determination of trace Shachongdan with calcein-Pd2+].

A fluorometric determination of trace Shachongdan (SCD) [(CH3)2NHCH (CH2S2O3- )CH2S2O3Na x H2O] is described. The method is based on the calcein display fluorescence in pH6-7 phosphate buffer solution, it react with Pd2+ to the fluorescence disappeared. The complex of SCD-Pd2+ is more stability than the complex of calcein-Pd2+, when SCD react with calcein -PdZ+, the calcein can be freed and its fluorescence appears once again. The fluorescence excitation and emission wavelenghts are 494 and 514nm. The linear range is 2 x 10(-7) mol/L-3 x 10(-6)mol/L and the detection limit is 6 x 10(-8)mol/L.

Fluoresceins↗
PubMed1997

Adoptive transfer of murine cytomegalovirus-immune lymph node cells prevents retinitis in T-cell-depleted mice.

PURPOSE: The purpose of this study was to determine whether adoptive transfer of murine cytomegalovirus (MCMV)-immune lymph node cells prevents retinitis in immunosuppressed mice. METHODS: Adult BALB/c mice were thymectomized and T-cell depleted using rat monoclonal antibodies specific for mouse CD4+ and CD8+ T-cells. The level of rat immunoglobulin G in the treated mice was monitored by enzyme-linked immunosorbent assay. Immune cells were labeled with PKH26-GH immediately before adoptive transfer, and flow cytometry was used to determine the percentage of adoptively transferred T-cells (PKH+, fluorescein isothiocyanate [FITC+]) in the spleens of the recipient mice 3 days after transfer. The ability of adoptively transferred cells to protect from retinitis was studied in T-cell-depleted mice injected with MCMV through the supraciliary route. Mice received 4 x 10(7) in vitro-restimulated MCMV-immune cells, 4 x 10(7) freshly isolated MCMV-immune cells, 4 x 10(7) freshly isolated ovalbumin-immune cells, or no cells (control group). RESULTS: The best time to balance depletion of endogenous T-cells with persistence of transferred cells was 3 weeks after T-cell depletion. Both restimulated and freshly isolated MCMV-immune cells conferred protection from retinitis. Freshly isolated ovalbumin-immune lymph node cells did not prevent retinitis, indicating that protection was virus-specific and merely was not because of transfer of antigen-activated lymph node cells. CONCLUSIONS: Adoptive immunotherapy has been used to prevent cytomegalovirus (CMV) infection in patients who have undergone transplantation, and, by extrapolation, the results of these studies suggest that adoptive immunotherapy with human CMV-specific immune cells might be used to prevent or ameliorate CMV retinitis in immunocompromised patients.

Animals↗
PubMed1997

Diagnosis of primary liver cancer using lectin affinity chromatography of serum alkaline phosphatase.

Serum alkaline phosphatase (sALP) can be separated into unbound liver type (L-ALP) and bound bone type (B-ALP) by means of WGA affinity chromatography. The L-ALP from the sera of normal adults and various liver diseases was found to show different chromatographic behaviours on DSA affinity column with multiple peaks of ALP activity after the L-ALP was treated with neuraminidase to remove the terminal sialic acids on the sugar chain of L-ALP. The L-ALP from normal sera contained no bound activity on DSA, whereas that from acute or chronic hepatisis, liver cirrhosis and biliary obstruction had a significant amount of bound fractions with weak and intermediate affinity. The strongly bound fraction(s) was only present in the L-ALP serum from primary liver cancer (PLC) and the positive rate of its appearance was 100% in 38 cases of PLC, including 8 alpha-fetoprotein (AFP) negative cases. The WGA chromatography can be skipped and similar results are obtained. The percentage of the strongly bound fraction in serum L-ALP was not related to the level of either sALP activity or AFP, and the appearance of the strongly bound fraction is attributed to the structural difference of sugar chains in L-ALP. Therefore, this L-ALP fraction may be assumed as a new index in the diagnosis of PLC, and the different profiles of sALP or L-ALP on DSA chromatography may be used in the differential diagnosis of benign and malignant liver diseases.

Alkaline Phosphatase↗
PubMed1997

Extractive L-lactic acid fermentation with immobilized Rhizopus oryzae in a three-phase fluidized bed.

The Rhizopus oryzae was immobilized by the calcium alginate entrapment method. A three-phase fluidized-bed bioreactor was designed to perform the immobilized-cell L-lactic acid fermentation. A solvent extraction column was coupled with the bioreactor to remove L-lactic acid from the fermentation broth. The TRPO was selected as solvent and sulfonated kerosene as diluent. The results indicated that the pH value in the broth was regulated above pH 3.5 and the fermentation rate was as high as 11 g L-lactic acid per hour per liter of beads. A mathematical model was proposed to describe the concentration of L-lactic acid in the extractive fermentation.

Fermentation↗
PubMed1997

Analysis of clonality of lymphocytic leukemia and lymphoma by T-cell receptor gene rearrangement.

OBJECTIVE: To analyse the relationship between the number of T-cell receptor (TCR) gamma gene rearrangement and clonality of malignant cells in lymphocytic leukemia and lymphoma. METHODS: The TCR gamma gene characteristics of 73 cases of lymphocytic leukemia and lymphoma and other diseases that had presented 1 or 2 prominent bands of amplified TCR gamma VI subgroups-J1/2 gene rearrangement (GR) were detected by polymerase chain reaction-restriction enzymes (PCR-RE), heteroduplex formation (HDF), DNA sequencing and single-strand conformational polymorphism (SSCP). RESULTS: Thirty-four percent patients had 2 of TCR gamma GR (biallelic rearrangement); twenty-six percent had 1 of TCR gamma GR; fifty-four percent of acute lymphocytic leukemia's and nineteen percent of non-Hodgkin's lymphomas (NHL) had 2 of TCR gamma GR. HDF could rapidly confirm more than 1 of alleles while more alleles were difficult to be recognized by restriction analysis. Sense and antisense strands of heteroduplex were composed of 2 of TCR gamma GR respectively. By combining HDF method, oligoclonalities in three patients (2 acute lympholytic leukemia and 1 myelodysplastil syndrome and clone evolution in one NHL were found. CONCLUSIONS: The fact that many patients had 2 of TCR GR means that complications of two neoplastic clones can be affirmed only if more than 2 of TCR GR are found. HDF can be used to detect the clonality, oligoclonality and polyclonality of lymphoid cells in lymphocytic leukemia and lymphoma by analysis of the difference of gene segments. HDF is a reliable method for the clone evolution research of lymphoid malignancies in progression.

Base Sequence↗
PubMed1997

Study on the hydrolyzate of sugarcane bagasse to ethanol by fermentation.

Study of glucose and xylose utilization by Pichia stipitis in a limited oxygen supply condition revealed that the rate of glucose utilization decreased rapidly while that of xylose decreased slowly until the time that glucose and xylose were shown to level out, at which point the rate of xylose utilization increased rapidly. Based on the results, ethanol fermentation technology in continuous connective tower fermenters was advanced, e.g., fermentation by P. stipitis in an airlift loop tower focusing on xylose utilization and then residue glucose utilization by Saccharomyces cerevisiae in an overflow tower. When the fed hydrolyzate of bagasse was concentrated in five folds and the dilution rate was 0.1 h-1, the total utilization ratio of reducing sugar was 97.2%; the concentration of ethanol was 46.4 g/L.h.

Cellulose↗
PubMed1997

[Suppression of metastatic phenotype of cloned mouse lung adenocarcinoma cells by transfer of human genomic DNA].

OBJECTIVE: To isolate and identify human sequences with metastatic suppression ability. METHODS: Genomic DNA fragments isolated from normal human lung tissue were transfected into cloned highly metastatic mouse lung adenocarcinoma cells together with PSV2neo as selectable marker. RESULTS: 25 transfectants were cloned in medium containing G418 and Ouabain. Eight morphologically flat revertants exhibited a more normal phenotype, six clones containing human DNA were identified by a sensitive Inter Alu-PCR method. The rate of cell growth and colony formation in agar were detected in vitro. Clone 12, 20 and 32 showed a lower ratio than maternal untransfected cells. In vivo clone 12 showed more significent less spontaneous metastases in nude mice and syngeneic T739 mouse than control group. CONCLUSION: The results indicated that the inserted human DNA may be responsible for suppression of metastatic phenotype of mouse lung adenocarcinoma cells.

Adenocarcinoma↗
PubMed1997

[A recombinant autoantigen U 1 RNP 70,000: expression in E. coli. and its serodiagnostic application].

OBJECTIVE: To express the recombinant autoantigen U 1 RNP 70,000 and to evaluate its serodiagnostic value. METHOD: We used molecular cloning techniques and immunoblotting technique. RESULTS: The recombinant proteins had authentic U 1 RNP 70,000 antigenicity, with the molecular weight corresponding to their theoretical value. 112 of 115(97.4%) anti-70,000 positive sera(IBT) could be detected by r 70,000. CONCLUSIONS: r 70,000 has good specificity and can be used in further detailed epitopes mapping. r 70,000 can be put into use for serodiagnostic detection.

Autoantigens↗
PubMed1997

Reciprocal changes in p27(Kip1) and p21(Cip1) in growth inhibition mediated by blockade or overstimulation of epidermal growth factor receptors.

Many human epithelial tumors express high levels of epidermal growth factor (EGF) receptors. A human-mouse chimeric version of anti-EGF receptor monoclonal antibody (mAb) C225, which blocks receptor activation and produces inhibition of cell proliferation, is currently being investigated in clinical trials. When cells bear high numbers of EGF receptors, either complete blockade of receptors with mAb 225 or full activation of receptors with EGF results in inhibition of proliferation. In the present study, we have explored the molecular mechanisms explaining how a receptor inhibitor, mAb 225, and a receptor activator, EGF, can both produce growth inhibition of A431 human squamous epithelial carcinoma cells. We reported previously that inhibition of A431 cells by EGF is associated with up-regulation of p21(Cip1). We now demonstrate that mAb 255-mediated inhibition is associated with up-regulation of p27(Kip1), which binds to and inactivates cyclin-dependent kinase-2 activity and produces cell cycle arrest in G1. Furthermore, inhibition by mAb 225 can be overcome by titrating the cultures with increasing concentrations of EGF, which is accompanied by a concurrent fall in the level of p27(Kip1). At properly titrated concentrations of mAb 225 and EGF, the inhibitory activities of both mAb 225 and EGF are counterbalanced and abolished. When EGF concentrations reach levels high enough to compete with mAb to produce near-saturating levels of receptor activation, p27(Kip1) falls below basal levels; however, the concomitant marked rise in the level of p21(Cip1) results in growth inhibition. Our data suggest that although p27(Kip1) and p21(Cip1) are induced and act independently, they play reciprocal roles in mediating inhibition of A431 cell growth by blockade of EGF receptors with mAb 225 and by activation of receptors with saturating concentrations of EGF.

Animals↗
PubMed1996

Loss of heterozygosity in normal tissue adjacent to breast carcinomas.

Loss of heterozygosity (LOH) was detected in morphologically normal lobules adjacent to breast cancers. The most frequent aberration was at chromosome 3p22-25; of ten cases with this LOH in the carcinoma, six displayed the same LOH in adjacent normal lobules. This suggests that in a subset of sporadic breast cancers, a tumor suppresser gene at 3p22-25 may be important in initiation or early progression of tumorigenesis. Among sixteen breast cancers with LOH at 17p13.1 and five breast cancers with LOH at 11p15.5, one case each displayed the same LOH in adjacent normal lobules. Thus the molecular heterogeneity that characterizes invasive breast cancers may occur at the earliest detectable stages of progression.

Alleles↗
PubMed1996

Function of RNA secondary structures in transcriptional attenuation of the Bacillus subtilis pyr operon.

The Bacillus subtilis pyr operon is regulated by exogenous pyrimidines by a transcriptional attenuation mechanism. Transcription in vitro from pyr DNA templates specifying attenuation regions yielded terminated and read-through transcripts of the expected lengths. Addition of the PyrR regulatory protein plus UMP led to greatly increased termination. Synthetic antisense deoxyoligonucleotides were used to probe possible secondary structures in the pyr mRNA that were proposed to play roles in controlling attenuation. Oligonucleotides predicted to disrupt terminator structures suppressed termination, whereas oligonucleotides predicted to disrupt the stem of antiterminator stem-loops strongly promoted termination at the usual termination site. Oligonucleotides that disrupt a previously unrecognized stem-loop structure, called the anti-antiterminator, the formation of which interferes with formation of the downstream antiterminator, suppressed termination. We propose that transcriptional attenuation of the pyr operon is governed by switching between alternative antiterminator versus anti-antiterminator plus terminator structures, and that PyrR acts by UMP-dependent binding to and stabilization of the anti-antiterminator.

Bacillus subtilis↗
PubMed1996

Surgically defined prognostic parameters in patients with early cervical carcinoma. A multivariate survival tree analysis.

BACKGROUND: This study was performed to identify a statistical combination of independent pathologic and clinical features that best predict 5-year disease free survival (DFS) in patients with early stage cervical carcinoma treated by radical hysterectomy. The main goal of the study was to identify subsets of patients based on risk factors with maximal differences in DFS. METHODS: Three hundred and seventy patients were found for whom complete clinical and pathologic material, including cone and cervical biopsies, were available for analysis. Variables studied included age, weight, race, marital status, economic status, tumor size (TS), depth of invasion (DI), lymph-vascular space involvement (LVSI), cell type, tumor grade, lymph node metastasis (LNM), and number of lymph nodes removed. Patients with LNM, parametrial involvement, and positive or close surgical margins were offered postoperative radiation. After excluding patients with microinvasive and small cell carcinoma, data from the remaining 301 patients were submitted to univariate and multivariate analyses to define those variables that best predict DFS. RESULTS: Univariate analysis showed that, ranked by degree of significance, DI, TS, LVSI, LNM, tumor volume (TV) and clinical stage were significant in predicting survival. Significant (P < 0.05) single parameters and other variables considered important were chosen for multivariate analysis, including the creation of a survival tree. With this method, DI (< or = 6 mm and > 2 cm), LVSI, age (> or = 40 yrs), and LNM were found to be the best combination of risk factors to define prognosis. CONCLUSIONS: The multivariate survival tree analysis maximally separates patients with early stage invasive carcinoma of the cervix into 3 subgroups with 5-year DFS of 91%, 68%, and 43%, respectively. The authors excluded patients with microinvasive carcinoma (SGO, Society of Gynecologic Oncologists), who have an excellent DFS of 100%, and patients with small carcinoma, who have a poor DFS of 36.4% based on cell type alone, to define independent risk factors that maximally separate the remaining patients by DSF. The survival tree prognostic scoring system is easy to apply, and only requires DI (mm), LVSI (+, -), LNM, and age to assign an individual patient to one of three risk groups.

Adult↗