Biomedical subjects

B Gu

Publications and source records attributed to B Gu.

At least 19 recordsLinked to original sources

PubMed2002

The effect of solvent concentration on the use of palladized-iron for the step-wise dechlorination of polychlorinated biphenyls in soil extracts.

This report describes the application of palladized iron (Pd/Fe) to the dechlorination of polychlorinted biphenyls (PCBs) at ambient temperature. Experiments supported by congener-specific analyses demonstrated that dechlorination occurs in a step-wise fashion with the meta-chlorines being more reactive than ortho-chlorines. Over the course of the laboratory experiments, complete conversion to biphenyl was observed. The process was also tested with PCBs dissolved in high (40-60%) concentrations of ethanol and isopropanol as a means of simulating solutions generated by commercial soil and solid waste extraction processes. The reaction rate was sensitive to the percentage of solvent but complete dechlorination was still indicated. Tests with soil extracts from a contaminated site demonstrated that there were no apparent interferences from asphalt and other miscellaneous debris. Short-duration tests with highly contaminated PCB solutions from a hazardous waste site demonstrated efficient dechlorination although there was a reduction in reaction rate with time.

Dose-Response Relationship, Drug↗

PubMed2001

P2Y(11) receptor expression by human lymphocytes: evidence for two cAMP-linked purinoceptors.

The effects of extracellular ATP, ADP, AMP and adenosine on cAMP accumulation have been studied in freshly isolated B-lymphocytes from patients with chronic lymphocytic leukemia. Extracellular ATP and several nucleotide analogs stimulated cAMP accumulation with the following order of potency: ATP (EC(50)=120+/-20 microM)>ADP>>AMP. ADP was less effective than ATP and may be a partial agonist. AMP exhibited variable but generally weak activity. The stable analog of ATP, alpha,beta-methylene ATP (EC(50)=110+/-15 microM) also stimulated cAMP accumulation and exhibited similar efficacy to ATP. The P2Y(2) receptor agonist, UTP had no effect on intracellular cAMP levels. Adenosine and the A(2A)/A(2B) receptor agonist, 5'-N-ethylcarboxamidoadenosine (NECA) also stimulated cAMP accumulation in CLL lymphocytes. Adenosine deaminase inhibited the cAMP response to adenosine but had no effect on the ATP-induced cAMP response. On the other hand, the AMP analog, adenosine 5'-thiomonophosphate, (AMPS; 1.0 mM) inhibited ATP-induced and alpha,beta-methylene ATP-induced cAMP production but had no effect on adenosine-induced cAMP production. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed the presence of P2Y(11) receptor as well as A(2A) and A(2B) receptor mRNA in chronic lymphocytic leukemia lymphocytes. However, A(2B) receptors would appear to be relatively ineffective because the A(2A) selective agonist, CGS-21680 exhibited comparable efficacy to NECA. Furthermore, the A(2A)-selective antagonist 8-(3-chlorostyryl)-caffeine (CSC) right-shifted the concentration-response curve for NECA. Taken together, the data indicate that ATP induces cAMP accumulation via the activation of P2Y(11) receptors whereas adenosine induces cAMP accumulation via the activation of A(2A) receptors. Coordinate activation of P2Y(11) and A(2A) receptors may influence the developmental fate of normal B-lymphocytes.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed2001

Regeneration of perchlorate (ClO4-)-loaded anion exchange resins by a novel tetrachloroferrate (FeCl4-) displacement technique.

Selective ion exchange is one of the preferred treatment technologies for removing low levels of perchlorate (ClO4-) from contaminated water because of its high efficiency and minimal impact on water quality through the addition or removal of chemicals and nutrients. However, the exceptionally high affinity of ClO4- for type I anion-exchange resins makes regeneration with conventional NaCl brine extremely difficult and costly for practical applications. The present study entails the development of a novel regeneration methodology applicable to highly selective anion-exchange resins. Tetrachloroferrate (FeCl4-) anions, formed in a solution of ferric chloride and hydrochloric acid (e.g., 1 M FeCl3 and 4 M HCl), were found to effectively displace Cl04- anions that were sorbed on the resin. A mass-balance analysis indicated that a nearly 100% recovery of ion-exchange sites was achieved by washing with as little as approximately 5 bed volumes of the regenerant solution in a column flow-through experiment There was no significant deterioration of the resin's performance with respect to ClO4- removal after repeated loading and regeneration cycles. Thus, the new methodology may offer a cost-effective means to regenerate ClO4- -loaded resins with improved regeneration efficiency, recovery, and waste minimization in comparison with conventional brine regeneration techniques.

Anion Exchange Resins↗

PubMed2001

Electronic structure and field-emission characteristics of open-ended single-walled carbon nanotubes.

The field-emission mechanism of open-ended single-walled carbon nanotubes (SWNTs) is studied. Owing to electronic effects that directly alter the bonding mode and remarkably influence the work function, an open-ended SWNT has much better field-emission properties than a closed SWNT; owing to geometrical effects that slightly influence the work function and the amplification factor, an open-ended SWNT with relaxation has higher threshold voltage and higher current density compared to one without relaxation. It is suggested that adjusting the localized electronic states of the emitting regions, by electronic and geometrical means, could improve the field-emission properties of carbon nanotubes.

Journal Article↗

PubMed2001

Impaired transendothelial migration of B-CLL lymphocytes: a defect linked to low L-selectin expression.

The emigration of lymphocytes from blood into lymph nodes is regulated by the expression of the adhesion molecule, L-selectin on the lymphocyte surface which arrests the rolling of the cell on the vessel wall and allows firmer adhesive interactions to develop. The expression of L-selectin on B-CLL lymphocytes is less than half that on normal lymphocytes and this difference correlates with an impaired capacity of B-CLL lymphocytes to migrate beneath a monolayer of human umbilical vein endothelial cells. Both the B-cell and T-cell lymphocytes from normal subjects and B-CLL patients show down-regulation of L-selectin and CD23 after transendothelial migration. The reduced expression of L-selectin on B-CLL lymphocytes leads to a relative "trapping" of these cells in the vascular space and is one factor contributing to the elevation of peripheral lymphocyte count.

B-Lymphocytes↗

PubMed2001

Analysis of hypermutation of the 5' noncoding region in the BCL-6 gene.

OBJECTIVE: To investigate BCL-6 gene mutations in Chinese populations with B-cell non-Hodgkin's lymphoma. METHODS: Polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and direct DNA sequencing were used to identify mutations in the 5' noncoding region of the BCL-6 gene in a total of 40 cases of diffuse large-cell lymphoma (DLCL) and follicular lymphoma (FL). RESULTS: Nine cases were found to have base substitutions. The incidence of BCL-6 gene mutation and the frequency of single-base changes were approximately 25.7% and (0.56-1.10) x 10(-2)/bp, respectively. CONCLUSIONS: The 5' regulatory region of the BCL-6 gene undergoes frequent somatic hypermutation during lymphomagenesis and the identification of BCL-6 gene hypermutations provides a molecular marker for confirmatory diagnosis of B-NHL.

5' Flanking Region↗

PubMed2001

Phosphorus removal from Everglades agricultural area runoff by submerged aquatic vegetation/limerock treatment technology: an overview of research.

The 1994 Everglades Forever Act mandates the South Florida Water Management District and the Florida Department of Environmental Protection to evaluate a series of advanced treatment technologies to reduce total phosphorus (TP) in Everglades Agricultural Area runoff to a threshold target level. A submerged aquatic vegetation/limerock (SAV/LR) treatment system is one of the technologies selected for evaluation. The research program consists of two phases. Phase I examined the efficiency of SAV/LR treatment system for TP removal at the mesocosm scale. Preliminary results demonstrate that this technology is capable of reducing effluent TP to as low as 10 microg/L under constant flows. The SAV component removes the majority of the influent soluble reactive P, while the limerock component removes a portion of the particulate P. Phase II is a multi-scale project (i.e., microcosms, mesocosms, test cells and full-size wetlands). Experiments and field investigations using various environmental scenarios are designed to (1) identify key P removal processes; (2) provide management and operational criteria for basin-scale implementation; and (3) provide scientific data for a standardized comparison of performance among advanced treatment technologies.

Agriculture↗

PubMed2001

[Change of cone's motion perception in patients with primary open angle glaucoma].

OBJECTIVE: To assess the change of cone's motion perception in primary open angle glaucoma (POAG). METHODS: Equi-luminance random dots moving test was used to determine the change of motion perception of blue, green and red cones in 51 eyes with POAG. To isolate the three kinds of cones, the blue, green and red visual targets were displayed on the yellow, purple and blue-green background respectively. RESULTS: The direction discrimination thresholds of motion perception from blue, green and red cones were all damaged in POAG compared to that of the normal group, and among them the blue cone was the most obviously damaged. CONCLUSIONS: These findings indicate that cone's motion perception, especially the blue cone's, may reveal pre-clinical visual nerve damage in POAG.

Adolescent↗

PubMed2001

Motion perception of short-wavelength sensitive cones in glaucoma using random dots moving.

PURPOSE: To determine whether motion perception of short-wavelength sensitive(SWS) cones is capable of predicting primary open angle glaucoma(POAG) optic neuropathy. METHODS: Motion perceptions of SWS cones were isolated by Blue random dot stimulus displayed on the Yellow background, then the detecting displacement threshold of motion perception from SWS cone in POAG was measured, and compared with the age-matched normal group. RESULTS: The detecting displacement thresholds of motion perception from SWS cones in 8 sites of 15 degrees were all elevated in POAG compared with the normal group. CONCLUSION: These findings suggest that motion perception of SWS cones may reveal preclinical visual nerve damage in early POAG.

Adolescent↗

PubMed2001

Potentiation of docetaxel antitumor activity by batimastat against mouse forestomach carcinoma.

OBJECTIVE: To improve the treatment of tumors, we studied the combined effects of docetaxel and batimastat (BB-94) on mouse forestomach carcinoma (MFC), and compared them with doxorubicin. METHODS AND RESULTS: In vitro, growth curve analysis, MTT assay and clonogenic assay used to determine the cytotoxic effect of docetaxel or/and BB-94 on MFC cell showed that docetaxel but not BB-94 had a significant cytotoxicity, and the effect of docetaxel wasn't enhanced by BB-94. In early stage MFC tumor model, obvious antitumor effect of docetaxel or doxorubicin given i.v. at maximum tolerated dose (MTD, docetaxel: 20 mg/kg; doxorubicin: 6 mg/kg) every 4 days for 3 injections (q4d x 3), even that of BB-94 (30 mg/kg i. p. qd x 20) was observed. Tumor growth inhibition was greater for docetaxel-batimastat (96.0%) than for doxorubicin-batimastat (88.0%), docetaxel (89.0%), doxorubicin (68.0%) and BB-94 (33.0%), and the effect of docetaxel could be potentiated by BB-94. Docetaxel also showed activity against advanced stage MFC tumor in dose-dependent manner, and was more effective at MTD than doxorubicin with 4/5 regressions, 46.5 days tumor growth delay and 2.8log(10) tumor cell kill. CONCLUSION: Our results suggest that in the MFC model with dose and schedule used, docetaxel is an effective cytotoxic new drug against MFC tumor and BB-94 enchances the antitumor activity of docetaxel.

Animals↗

PubMed2000

The RNA helicase and nucleotide triphosphatase activities of the bovine viral diarrhea virus NS3 protein are essential for viral replication.

Helicase/nucleoside triphosphatase (NTPase) motifs have been identified in many RNA virus genomes. Similarly, all the members of the Flaviviridae family contain conserved helicase/NTPase motifs in their homologous NS3 proteins. Although this suggests that this activity plays a critical role in the viral life cycle, the precise role of the helicase/NTPase in virus replication or whether it is essential for virus replication is still unknown. To determine the role of the NS3 helicase/NTPase in the viral life cycle, deletion and point mutations in the helicase/NTPase motifs of the bovine viral diarrhea virus (BVDV) (NADL strain) NS3 protein designed to abolish either helicase activity alone (motif II, DEYH to DEYA) or both NTPase and helicase activity (motif I, GKT to GAT and deletion of motif VI) were generated. The C-terminal domain of NS3 (BVDV amino acids 1854 to 2362) of these mutants and wild type was expressed in bacteria, purified, and assayed for RNA helicase and ATPase activity. These mutations behaved as predicted with respect to RNA helicase and NTPase activities in vitro. When engineered back into an infectious cDNA for BVDV (NADL strain), point mutations in either the GKT or DEYH motif or deletion of motif VI yielded RNA transcripts that no longer produced infectious virus upon transfection of EBTr cells. Further analysis indicated that these mutants did not synthesize minus-strand RNA. These findings represent the first report unequivocably demonstrating that helicase activity is essential for minus-strand synthesis.

Adenosine Triphosphatases↗

PubMed2000

Hepatitis B virus X protein activates expression of IGF-IR and VEGF in hepatocellular carcinoma cells.

OBJECTIVE: The expression of insulin-like growth factor I receptor (IGF-IR) and the vascular endothelial growth factor (VEGF) in HepG(2) cells transfected with a hepatitis B virus X (HBx) expression vector was investigated in an attempt to study their possible relationship to the growth of HBx-induced hepatocellular carcinoma (HCC). METHODS: The eucaryotic expression vector of HBx gene was constructed and introduced into HepG(2) cells. The modified cell HepaG(2)-X was synchronized in a quiescent state by culture of serum deprivation. The IGF-IR and VEGF were analyzed by immunohistochemical and Western blot technique. RESULTS: The positive rate of IGF-IR expression was 84%A3% in the transfected HBx gene cells, 26%A4% in X(0) control cells. The positive rate of VEGF expressed x cells was 83%A5%, X(0) cells was 28%A6% (P<0.001). The level of IGF-IR and VEGF in serum-starved x modified cells was 1.5 times higher than that of synchronized X(0) modified cells. CONCLUSION: Since the IGF-IR is a very important growth factor in sustaining the tumor abnormal growth and the VEGF has a crucial role in inducting tumor angiogenesis, our findings indicate that HBx may play an important role in the processes of HCC by activating IGF-IR and VEGF gene expression.

Carcinoma, Hepatocellular↗

PubMed2000

Cytotoxic effects of 5-fluorocytosine on melanoma cells transduced with cytosine deaminase gene.

To investigate the cytotoxic effects of 5-fluorocytosine on melanoma cells genetically modified with cytosine deaminase gene, the gene was transduced into the tumor cells with the retroviral method. The cytotoxicity effects of 5-fluorocytosine on the tumor cells were measured with the MTT assay and clonogenic assay. It was found that the prodrug 5-fluorocytosine had significant cytotoxic effects on melanoma cells transduced with cytosine deaminase in vitro. The IC50 value of 5-fluorocytosine on transgenic and nontransgenic melanoma cells was 572 microg/mL(-1) and 3870 microg/mL(-1), respectively. Our experiment demonstrated the potential value of the cytosine deaminase gene/5-fluorocytosine system in the treatment of melanoma.

3T3 Cells↗

PubMed2000

[Effects of hepatitis B virus X gene on apoptosis and the activity of telomerase in HepG(2) cells].

OBJECTIVE: To observe the effects of hepatitis B virus X gene on hepatic carcinoma. METHODS: The expression vectors of HBs gene and HBc gene (pCEP4-S and pCEP4-C) were transfected into HepG(2) cells by electroporation technique, and the cells, HepG(2) cells which contained the expression vectors of HBs (pCEP4-X) were recovered and cultured stably. The activity index of telomerase and the apoptosis rates in three cell lines were determined by PCR-ELISA and flow cytometry. RESULTS: The 39.50% of cells expressed HBx gene came into S-phase of cell cycle, and the activity index of telomerase was higher in the cell line (3.95 +/- 0.07) than in other cell lines and control (F=20.85, P<0.01; d'=2.15, P<0.05) after synchronized culture. Induced by antisense oligonucleotides against telomerase the apoptosis of cell line expressed HBx gene reduced (apoptosis rate: 1.75%). The activity of cells also reduced with the dose increase of the antisense oligonucleotides and it showed a dose-response relationship. CONCLUSION: The activity of HepG(2) cell can be increased and the cell apoptosis can be reduced by HBx gene. It may be another malignant process of hepatocytes.

Apoptosis↗

PubMed2000

Potentiation of docetaxel antitumor activity by batimastat against mouse forestomach carcinoma.

Docetaxel is a chemical compound belonging to the taxoid class of anticancer agents. Batimastat (BB-94) is the first matrix metalloproteinase inhibitor entering clinical trials. To improve the treatment of tumors, we studied the combined effects of docetaxel and batimastat on mouse forestomach carcinoma (MFC), and compared them with doxorubicin. In vitro growth curve analysis, MTT assay, and clonogenic assay were used to determine the cytotoxic effect of docetaxel or/and BB-94 on MFC. They showed that docetaxel, but not BB-94, had a significant cytotoxicity and that the effect of docetaxel was not enhanced by BB-94. In an early stage MFC tumor model, an obvious antitumor effect of docetaxel or doxorubicin given iv at maximum tolerated dose (MTD) was observed. Tumor growth inhibition was greater for docetaxel + BB-94 (96.0%) than for doxorubicin + BB-94 (88.0%), docetaxel (89.0%), doxorubicin (68.0%), and BB-94 (33.0%). Docetaxel showed activity against advanced stage MFC tumor in a dose-dependent manner and was more effective at MTD than doxorubicin, with 4/5 regression, 46.5 days tumor growth delay, and 2.8 log10 tumor-cell kill. Our results suggest that docetaxel is an effective new cytotoxic drug against MFC tumor and that BB-94 enhances the antitumor activity of docetaxel in the dose and schedule used.

Animals↗

PubMed2000

Impact of RT-PCR monitoring on the long-term survival in acute promyelocytic leukemia.

OBJECTIVE: To evaluate the impact of kinetics of molecular remission via retro-transcriptase polymerase chain reaction (RT-PCR) assay on the long-term survival in patients with acute promyelocytic leukemia (APL). METHODS: Seventy patients with newly-diagnosed APL in remission were involved in this study. Monitoring of minimal residual disease (MRD) was performed regularly by RT-PCR assay for PML-RAR alpha during consolidation. RESULTS: A 5-year relapse-free survival (RFS) and overall-survival (OS) were estimated as 46.8% +/- 8.4% and 69.9% +/- 9.4% for the whole group. Fifty-two (74.3%) patients got negative RT-PCR result at least once. Serial monitoring of RT-PCR was available in 38 cases and 24 (63.2%) patients presented with persistent negative PCR results. The achievement and continuous negative RT-PCR result was significantly related to the RFS. CONCLUSIONS: Achievement of negative RT-PCR in remission is associated with favorable RFS and OS. Continuous negative RT-PCR results are associated with long-term relapse-free survival and may be considered as potentially curative. RT-PCR assay for detection of MRD should be performed regularly during post-remission period as an important prognostic factor.

Adolescent↗

PubMed1999

A rhizobial homolog of IHF stimulates transcription of dctA in Rhizobium leguminosarum but not in Sinorhizobium meliloti.

Sequence inspection identified several potential IHF binding sites adjacent to the Rhizobium leguminosarum dctA promoter. IHF protected the -30 to -76 region from DNase I digestion, but systematic error in quantitative assays suggested that this protein DNA interaction is complex. IHF stimulated DctD-mediated transcriptional activation from the R. leguminosarum dctA promoter both in vivo and in vitro. In contrast to R. leguminosarum dctA, the Sinorhizobium meliloti dctA promoter region was found to have a much weaker match to the consensus IHF binding site and a low affinity for IHF. Moreover, IHF had no effect on transcriptional activation from the S. meliloti dctA promoter in vitro. A base substitution was introduced into the IHF binding site of R. leguminosarum dtA that reduced the affinity of the promoter regulatory region for IHF by approximately 30-fold and resulted in an eight-fold decrease in transcriptional activation in both R. leguminosarum and S. meliloti. These data suggest that both rhizobial species have an IHF homolog that stimulates DctD-mediated transcriptional activation from the R. leguminosarum dctA promoter. Consistent with this hypothesis, a 12.5 kDa protein was identified from R. leguminosarum as a putative homolog of IHF subunit beta by immunoblotting and N-terminal sequence analysis.

Amino Acid Sequence↗

PubMed1999

[Expression of HBsAg by using various eukaryotic expression vectors].

OBJECTIVE: To establish efficient eukaryotic expression system of HBsAg and its variants. METHODS: A series of expression vectors were constructed by cloning HBV S gene and its mutant genes from recombinant vector pBluescript pBKS(+)-HBs containing S gene and its mutant genes into eukaryotic expression vectors: pMEP4, pCEP4, pLXSN, PXT1, pcDNA3. These recombinant eukaryotic expression vectors were transfected into human hepatocellular carcinoma cells (HepG2). RESULTS: The cell lines expressing recombinant proteins were stably established. CONCLUSION: All expression vectors could express HBsAg and its variants, but their transfecting efficiency, expressing efficiency and stability of expression were different. The establishment of highly efficient expression system in this study paves the way for further study on biologic characters of HBsAg variants, genetic immunization and genetic therapy.

Eukaryotic Cells↗