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Biomedical subjects

J Liu

Publications and source records attributed to J Liu.

At least 145 records · Page 8Linked to original sources
PubMed2004

Observation of divergent-beam X-ray diffraction from a crystal of diamond using synchrotron radiation.

In 1947 Kathleen Lonsdale conducted a series of experiments on X-ray diffraction using a divergent beam external to a crystal sample. Unlike the Kossel technique, where divergent X-rays are excited by the presence of fluorescing atoms within the crystal, the use of an external divergent source made it possible to study non-fluorescing crystals. The resulting photographs not only illustrated the complexity of X-ray diffraction from crystals in a truly beautiful way, but also demonstrated unprecedented experimental precision. This long-forgotten work is repeated here using a synchrotron radiation source and, once again, considerable merit is found in Lonsdale's technique. The results of this experiment suggest that, through the use of modern 'third-generation' synchrotron sources, divergent-beam diffraction could soon enjoy a renaissance for high-precision lattice-parameter determination and the study of crystal perfection.

Computer Simulation↗
PubMed2004

Measurement of the electric form factor of the neutron at Q2=0.5 and 1.0 GeV2/c2.

The electric form factor of the neutron was determined from measurements of the d-->(e-->,e'n)p reaction for quasielastic kinematics. Polarized electrons were scattered off a polarized deuterated ammonia (15ND3) target in which the deuteron polarization was perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons in a large solid angle detector. We find G(n)(E)=0.0526+/-0.0033(stat)+/-0.0026(sys) and 0.0454+/-0.0054+/-0.0037 at Q(2)=0.5 and 1.0 (GeV/c)(2), respectively.

Journal Article↗
PubMed2004

RAD and the RAD Study-Annotator: an approach to collection, organization and exchange of all relevant information for high-throughput gene expression studies.

MOTIVATION: Gene expression array technology has become increasingly widespread among researchers who recognize its numerous promises. At the same time, bench biologists and bioinformaticians have come to appreciate increasingly the importance of establishing a collaborative dialog from the onset of a study and of collecting and exchanging detailed information on the many experimental and computational procedures using a structured mechanism. This is crucial for adequate analyses of this kind of data. RESULTS: The RNA Abundance Database (RAD; http://www.cbil.upenn.edu/RAD) provides a comprehensive MIAME-supportive infrastructure for gene expression data management and makes extensive use of ontologies. Specific details on protocols, biomaterials, study designs, etc. are collected through a user-friendly suite of web annotation forms. Software has been developed to generate MAGE-ML documents to enable easy export of studies stored in RAD to any other database accepting data in this format (e.g. ArrayExpress). RAD is part of a more general Genomics Unified Schema (http://www.gusdb.org), which includes a richly annotated gene index (http://www.allgenes.org), thus providing a platform that integrates genomic and transcriptomic data from multiple organisms. This infrastructure enables a large variety of queries that incorporate visualization and analysis tools and have been tailored to serve the specific needs of projects focusing on particular organisms or biological systems.

Abstracting and Indexing↗
PubMed2004

Single nucleotide polymorphisms and haplotypes of histamine N-methyltransferase in patients with gastric ulcer.

INTRODUCTION: Histamine plays a crucial role in the regulation of gastric acid secretion, which is involved in the pathogenesis of peptic ulcer. Histamine N-methyltransferase (HNMT) is the major metabolizing enzyme for histamine inactivation in human stomach. OBJECTIVE: This study aims to determine whether there exists a relationship between HNMT gene polymorphisms and the risk for gastric ulcer (GU). METHODS: 118 GU patients and 154 ethnically matched control subjects were enrolled and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assays were developed to genotype all these subjects for the T-1637C, C-411T, C314T and A1097T point mutations in HNMT gene. Haplotypes were reconstructed from the genotype data. RESULTS: Frequencies of the variant alleles in cases and controls were 0.398 vs 0.396 for T-1637C, 0.144 vs 0.110 for C-411T, 0.034 vs 0.042 for C314T, and 0.242 vs 0.273 for A1097T, respectively, with no significant difference for any locus between the two groups (all P > 0.05). Also the frequencies of genotypes, haplotypes and haplotype pairs based on these polymorphisms did not differ significantly between cases and controls. CONCLUSION: This study provided no evidence for the involvement of HNMT polymorphisms in the susceptibility to GU.

Adolescent↗
PubMed2004

Laparoscopic left hemihepatectomy for hepatolithiasis.

To assess the feasibility of hepatolithiasis treatment using laparoscopic liver resections, a prospective study of laparoscopic liver resections was undertaken in selected patients with left intrahepatic stone disease. The patients underwent a laparoscopic left lobectomy to try to alleviate the symptoms of their disease. Two patients were operated on successfully. Mean blood loss was 400-600 ml. Laparoscopic resections are feasible methods of treatment for selected patients with left intrahepatic stone disease.

Adult↗
PubMed2004

The activation mechanism of class-C G-protein coupled receptors.

Class-C G-protein coupled receptors (GPCRs) represent a distant group among the large family of GPCRs. This class includes the receptors for the main neurotransmitters, glutamate and gamma-aminobutyric acid (GABA), and the receptors for Ca(2+), some taste and pheromone molecules, as well as some orphan receptors. Like any other GPCRs, class-C receptors possess a heptahelical domain (HD) involved in heterotrimeric G-protein activation, but most of them also have a large extracellular domain (ECD) responsible for agonist recognition and binding. In addition, it is now well accepted that these receptors are dimers, either homo or heterodimers. This complex architecture raises a number of important questions. Here we will discuss our view of how agonist binding within the large ECD triggers the necessary change of conformation, or stabilize a specific conformation, of the heptahelical domain leading to G-protein activation. How ligands acting within the heptahelical domain can change the properties of these complex macromolecules.

Allosteric Site↗
PubMed2004

Discoloration of methylene blue and wastewater from a plant by a Fe/Cu bimetallic system.

Using a Fe/Cu bimetallic system (Fe/Cu system), the discoloration of both methylene blue in aqueous solution and the colored wastewater from a plant was investigated under the anaerobic condition in batch or continuous reactors. Results show that the Fe/Cu system effectively removed the color with over 88% of color removal efficiency for both methylene blue solution and the wastewater from the plant in batch test. Color removal efficiencies increased rapidly with Fe/Cu dosage and reaction time, respectively, at initial time and slowly to stable values. Optimum pH was neutral range. In addition, in continuous test it also removed the color of the wastewater from the plant with 63% of discoloring efficiency under the condition of 2 h of hydraulic retention time and neutral range of pH (7.0-8.3). High discoloring efficiencies with low chemical oxygen demand removal efficiencies were found in all experiments. The reduction of chromophores in pollutants was the main mechanism of the discoloration in the Fe/Cu system.

Color↗
PubMed2004

Determination of bull sperm membrane permeability to water and cryoprotectants using a concentration-dependent self-quenching fluorophore.

The objective of this study was to determine the membrane permeability characteristics of bovine spermatozoa. These included the hydraulic conductivity (Lp), the permeability coefficients (Ps) of four common cryoprotective agents (CPAs) and the associated reflection coefficients (sigma). Stopped-flow fluorometry was applied in order to capture rapid cell volume changes under anisosmotic conditions in the absence or presence of permeant solutes (CPAs). This technique utilizes a concentration-dependent self-quenching entrapped fluorophore. The resulting cell volume changes were used in three-parameter fitting calculations to compute Lp in the absence of permeant solutes and Ps and Lp in the presence of permeating solutes (CPAs) at 22 degrees C. The hydraulic conductivity in the absence of permeating solutes was estimated to be 0.68+/-0.05 microm/min/atm (mean+/-SEM). Hydraulic conductivity (Lp) in the presence of CPAs was 0.91+/-0.27 (mean+/-SEM), 0.29+/-0.04, 0.42+/-0.05, and 0.39+/-0.03 microm/min/atm in the presence of dimethylsulfoxide (Me(2)SO), glycerol, propylene glycol (PG), and ethylene glycol (EG), respectively. The values for Ps were estimated to be 1.72+/-0.36, 1.75+/-0.03, 2.47+/-0.24, and 1.49+/-0.33 x 10(-3)cm/min for Me(2)SO, glycerol, PG, and EG, respectively. The data were used to simulate volume excursions during addition and removal of CPA, to predict the different effects of the four CPAs.

Animals↗
PubMed2004

Galectin-1 expression correlates with the regenerative potential of rubrospinal and spinal motoneurons.

Axotomized spinal motoneurons are able to regenerate to their peripheral targets, whereas injured rubrospinal neurons that lie completely within the CNS fail to regenerate. The differing cell body reactions to axotomy of these two neuronal populations have been implicated in their disparate regenerative ability. Recently, the lectin galectin-1 has been shown to be involved in both spinal motoneurons and primary afferent regeneration. Using in situ hybridization, we compared the endogenous galectin-1 mRNA expression in spinal motoneurons and rubrospinal neurons after axotomy. We found that 7 and 14 days after axotomy, galectin-1 mRNA increased in spinal motoneurons but decreased in rubrospinal neurons. Infusion of the brain-derived neurotrophic factor into the vicinity of the injured rubrospinal nucleus, which we have previously shown to increase the regenerative capacity of rubrospinal neurons, significantly increased galectin-1 mRNA compared with uninjured control levels. Thus, the expression of galectin-1 in neurons correlates with the regenerative propensity.

Analysis of Variance↗
PubMed2004

Activation of human coagulation system by liver-derived clotting factors of Banna minipig inbred line.

The liver synthesizes most of the coagulation factors that play a major role in arresting hemorrhage. Matching hepatic coagulation factors is an important premise in successful xenotransplantation. As a unique inbred pig, the Banna minipig inbred (BMI) animals have a huge potential value for pig-to-human xenotransplantation, due to its clear genetic background and tiny interindividual differences. Whether the coagulation factors synthesized by porcine liver can trigger human clotting pathways has not been reported. This study focused on the activities of BMI coagulant factors synthesized exclusively by the liver to activate human clotting pathways. In these experiments we prepared coagulant factors II, V, VII, X, and XII synthesized exclusively by liver from BMI and humans. The factors were used in common correction tests, added to the corresponding factor-deficient human plasma to determine prothrombin times or activated partial thromboplastin time, thereby calculating BMI and human coagulant factor activities. BMI clotting factors XII, VII, and X triggered human intrinsic, extrinsic, and common pathways, respectively. BMI clotting factors II, V, VII, X, and XII activities were 3.2-, 3.7-, 4.7-, 2.9-, and 4.5-fold as potent as those from humans.

Adult↗
PubMed2004

Suppression of human peripheral blood lymphocyte proliferation by immortalized mesenchymal stem cells derived from bone marrow of Banna Minipig inbred-line.

This study sought to investigate whether mesenchymal stem cells (MSC) derived from Banna Minipig Inbred-line (BMI-MSC) suppressed human peripheral blood lymphocyte (hPBLs) proliferation in a one-way mixed lymphocyte reaction system. BMI-MSC failed to stimulate proliferative responses by hPBLs, which were activated by allogenic endothelial cells, BMI-PBLs and non-specific mitogenic stimuli. Furthermore, BMI-MSC also suppressed proliferation of hPBLs stimulated by mismatched allogenic, as well as xenogenic PBLs, and the mitogenic stimulus ConA. The suppression occurred in dose-dependent fashion when the ratio of hPBLs to BMI-MSC varied from 1 to 5 fold; fewer, BMI-MSC (0.001 to 0.01 times) showed no obvious suppression. When BMI-MSC were added to hPBLs stimulated for 72 hours, the proliferative suppression was still evident. Addition of anti-FasL or anti-TGF-beta1 antibody attenuated the proliferative suppression, while antibody against IL-10 had no effect on it. Further immunofluorescence analysis demonstrated that FasL and TGF-beta1 constitutively expressed BMI-MSC. These findings suggest that BMI-MSC suppress hPBLs proliferation relying on FasL and TGF-beta1 mediated pathways.

Animals↗
PubMed2004

An accurate approach to the design of channel hydraulic flocculators.

The design of flocculators for water treatment continues to be based on the generalized and simplistic concept of mean velocity gradient within the reaction zone. This approach makes little sense for hydraulic flocculators in which the turbulence conditions are heterogenous. A theoretical, experimental and computational fluid dynamics study is presented, in which a point-to-point approach is derived, allowing variations in turbulent kinetic energy to be taken into account in determining flocculation efficiency. Results for the point-to-point calculation are compared with experimental measurements of flocculation efficiency in a full-scale model of a channel hydraulic flocculator, and an extremely good fit is obtained, demonstrating the point-to-point approach to be an accurate method of determining flocculation efficiency in channel hydraulic flocculators. A design example is presented showing how the point-to-point approach can be used in practice. It is concluded that the point-to-point approach is a much better method of design than that based on the mean velocity gradient.

Equipment Design↗
PubMed2004

Identification of deficient mitochondrial signaling in apoptosis resistant leukemia cells by flow cytometric analysis of intracellular cytochrome c, caspase-3 and apoptosis.

Deficient activation of apoptosis signaling pathways may be responsible for treatment failure of malignant diseases. In primary leukemia samples the detection of deficient mitochondrial apoptosis signaling would enable identification of chemo-resistant cells. To investigate the key events of apoptosis at the mitochondrial level, we developed a flow cytometric method for simultaneous detection of mitochondrial cytochrome c release and caspase-3 processing using conformation sensitive monoclonal antibodies. This method proved to identify deficient mitochondrial apoptosis signaling in leukemia cells overexpressing Bcl-2 by a pattern of apoptosis resistance, deficient cytochrome c reduction and partial processing of caspase-3. In primary leukemia cells, reduction of cytochrome c and caspase-3 activation was induced by treatment with anticancer drugs in vitro. In leukemia cells of a patient with resistant disease, a pattern of deficient apoptosis signaling as in Bcl-2 transfected cells was observed, suggesting that deficient mitochondrial signaling contributed to the clinical phenotype of drug resistance in this patient. Flow cytometric analysis of mitochondrial apoptosis signaling may provide a useful tool for the prediction of drug resistance and treatment failure in primary leukemia.

Antibodies, Monoclonal↗
PubMed2004

The cardiolipin-binding domain of Bid affects mitochondrial respiration and enhances cytochrome c release.

Bid is cleaved by caspase 8 during apoptosis and the truncated Bid (tBid) translocates to mitochondria by targeting cardiolipin. Amino acids 103-162 of Bid were reported as the cardiolipin-binding domain (CBD). The EGFP-CBD fusion protein targets to mitochondria and induces apoptosis. Using [(3)H]cardiolipin, we proved that recombinant CBD binds cardiolipin similar to tBid and tBid(G94E), a mutant with a defective BH3 domain. CBD could induce cytochrome c release from isolated mitochondria, but much less potent than tBid. Free cardiolipin inhibited the CBD-induced cytochrome c release, suggesting that it may be mediated by interfering with mitochondrial cardiolipin, especially with the interaction between cytochrome c and cardiolipin. This is consistent with the findings that CBD induced cytochrome c release in Bax-deficient cells, and that CBD suppressed mitochondrial respiration through directly interfering with cardiolipin, a critical lipid involved in oxidative phosphorylation. These results indicate the functional importance of CBD in tBid-induced apoptosis.

Animals↗
PubMed2004

Linkage analysis of psychosis in bipolar pedigrees suggests novel putative loci for bipolar disorder and shared susceptibility with schizophrenia.

The low-to-moderate resolution of linkage analysis in complex traits has underscored the need to identify disease phenotypes with presumed genetic homogeneity. Bipolar disorder (BP) accompanied by psychosis (psychotic BP) may be one such phenotype. We previously reported a genome-wide screen in a large bipolar pedigree sample. In this follow-up study, we reclassified the disease phenotype based on the presence or absence of psychotic features and subgrouped pedigrees according to familial load of psychosis. Evidence for significant linkage to psychotic BP (genome-wide P<0.05) was obtained on chromosomes 9q31 (lod=3.55) and 8p21 (lod=3.46). Several other sites were supportive of linkage, including 5q33 (lod=1.78), 6q21 (lod=1.81), 8p12 (lod=2.06), 8q24 (lod=2.01), 13q32 (lod=1.96), 15q26 (lod=1.96), 17p12 (lod=2.42), 18q21 (lod=2.4), and 20q13 (lod=1.98). For most loci, the highest lod scores, including those with genome-wide significance (at 9q31 and 8p21), occurred in the subgroup of families with the largest concentration of psychotic individuals (> or =3 in a family). Interestingly, all regions but six--5q33, 6q21, 8p21, 8q24, 13q32 and 18q21--appear to be novel; namely, they did not show notable linkage to BP in other genome scans, which did not employ psychosis for disease classification. Also of interest is possible overlap with schizophrenia, another major psychotic disorder: seven of the regions presumed linked in this study--5q, 6q, 8p, 13q, 15q, 17p, and 18q--are also implicated in schizophrenia, as are 2p13 and 10q26, which showed more modest support for linkage. Our results suggest that BP in conjunction with psychosis is a potentially useful phenotype that may: (1) expedite the detection of susceptibility loci for BP and (2) cast light on the genetic relationship between BP and schizophrenia.

Bipolar Disorder↗
PubMed2004

Isolation of linoleic acid as an estrogenic compound from the fruits of Vitex agnus-castus L. (chaste-berry).

A methanol extract of chaste-tree berry (Vitex agnus-castus L.) was tested for its ability to displace radiolabeled estradiol from the binding site of estrogen receptors alpha (ERalpha) and beta (ERbeta). The extract at 46 +/- 3 microg/ml displaced 50% of estradiol from ERalpha and 64 +/- 4 microg/ml from ERbeta. Treatment of the ER+ hormone-dependent T47D:A18 breast cancer cell line with the extract induced up-regulation of ERbeta mRNA. Progesterone receptor (PR) mRNA was upregulated in the Ishikawa endometrial cancer cell line. However, chaste-tree berry extract did not induce estrogen-dependent alkaline phosphatase (AP) activity in Ishikawa cells. Bioassay-guided isolation, utilizing ER binding as a monitor, resulted in the isolation of linoleic acid as one possible estrogenic component of the extract. The use of pulsed ultrafiltration liquid chromatography-mass spectrometry, which is an affinity-based screening technique, also identified linoleic acid as an ER ligand based on its selective affinity, molecular weight, and retention time. Linoleic acid also stimulated mRNA ERbeta expression in T47D:A18 cells, PR expression in Ishikawa cells, but not AP activity in Ishikawa cells. These data suggest that linoleic acid from the fruits of Vitex agnus-castus can bind to estrogen receptors and induce certain estrogen inducible genes.

Breast Neoplasms↗
PubMed2004

Cultivation of aerobic granules in a sequential batch shaking reactor.

Aerobic granular sludge is a promising biotechnology for wastewater treatment system. In this report, aerobic granular sludge was successfully cultivated in a sequential batch shaking reactor in which horizontal circular flow could be formed by shaking. In this way, granulation and aeration could be simultaneously achieved. In comparison with sequential batch airlift reactor, more homogeneous circular flow was formed in the sequential batch shaking reactor. The aerobic granules obtained in the reactor were smooth, 1.2 mm in average diameter, and had a settling velocity of 50-52 m h(-1). In addition, an increase in the hydrophobicity of the cell surface of granules indicated that granulation could be related to the change in cell hydrophobicity. Finally, microbial observation showed that rod-shape and coccoid bacteria were the dominant species in mature granules. Results of this study have important implications on the mechanism of the granulation process and further practical application.

Bacteria, Aerobic↗