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H Liang

Publications and source records attributed to H Liang.

At least 37 records · Page 2Linked to original sources
PubMed2001

Monte Carlo simulation of morphologies of self-assembled amphiphilic diblock copolymers in solution.

The Monte Carlo method has been applied to simulate the process of the self-assembling of amphiphilic diblock copolymers in a selective solvent. The simulations illustrated that the aggregates morphologies of A-b-B diblock copolymers in solution strongly depend on the length of corona-forming segments, i.e., with the decrease of the corona-forming segments, the transition of spherical micelles to rodlike aggregates occurs, which are in accord with the experimental results of Eisenberg and co-workers [Science 268, 1728 (1995); Macromolecules 32, 2239 (1999); 31, 3509 (1998); 29, 6359 (1996); 31, 9399 (1998)].

Journal Article↗
PubMed2001

The subsequent effect of interaction between Co(2+) and human serum albumin or bovine serum albumin.

A notable hysteretic effect has been observed in the interaction of Co(II) with human serum albumin (HSA) or bovine serum albumin (BSA) using UV-Visible spectrometry at physiological pH (7.43), which shows that the binding between Co(II) and HSA or BSA may induce a slow transition of HSA or BSA from the conformation of weaker affinity for Co(II) to one of stronger affinity (A-B transition). The rate constants and activation parameters of this transition were measured and are discussed. It is inferred that such a conformation transition may occur due to the binding of the first Co(II) ion with the peptide segment of N-terminal residues 1-3, which results in a 'hinged movement' of the relatively hydrophobic 'valley' in the IA subdomain. This process leads to a slow conformational transition in the albumins, makes the other binding sites of Co(II) exposed, and shows a positive cooperativity effect. The LMCT (ligand-to-metal charge transition) bands of the Co(II)-HSA and Co(II)-BSA systems also show a kind of hypochromic effect featuring a dipole-dipole interaction mechanism. This phenomenon is rarely reported.

Animals↗
PubMed2001

Immunohistochemical and ultrastructural evidence that dendritic cells infiltrate stenotic aortocoronary saphenous vein bypass grafts.

We earlier speculated that antigen-presenting dendritic cells may be involved in the immune reactions leading to saphenous vein bypass graft failure. The purpose of this study was to confirm whether dendritic cells are present in stenotic human saphenous vein bypass grafts. Segments of stenotic saphenous vein grafts were explanted from 14 patients at re-do bypass operation and ten normal saphenous veins were harvested during femoro-popliteal grafting. Sections of specimens were analysed using cell type specific antibodies to identify dendritic cells (CD1a, S-100), T-lymphocytes (CD3), macrophages (CD68), smooth muscle cells (alpha-SMA) and endothelial cells (FVIII). Dual immunostaining, confocal immunofluorescent laser scanning microscopy and electron microscopy were used. Stenotic grafts showed structural alterations of intimal hyperplasia and varying degrees of atherosclerotic degeneration. No cells expressing CD1a and S-100 were observed in the intima and media of normal saphenous veins. Cells expressing these antigens were present around areas of medial neovascularization and within intimal atherosclerotic lesions in saphenous vein bypass grafts. Electron microscopy demonstrated the presence of cells containing a well-developed tubulovesicular system which is unique to cells from the dendritic cell family. Double immunohistochemistry and confocal immunofluorescent microscopy revealed the co-localization of T-lymphocytes with dendritic cells. Dendritic cells are present in stenotic saphenous vein bypass grafts. Dendritic cells may be responsible for antigen presentation and modulation of immune reactions in accelerated graft atherosclerosis through their interaction with T-lymphocytes.

Adult↗
PubMed2001

Expression of apoptosis-related proteins and structural features of cell death in explanted aortocoronary saphenous vein bypass grafts.

This study aimed to investigate the features of cell death occurring in aortocoronary saphenous vein bypass grafts. Human aortocoronary saphenous vein bypass grafts with angiographic luminal stenosis of > 75% were explanted from 14 patients at redo coronary artery bypass grafting. Proteins associated with apoptotic pathways were identified immunohistochemically using antibodies to Bcl-2, Fas, BAX, p53 and CPP32. Cells undergoing DNA fragmentation were identified by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). DNA synthesis was investigated using the antibody to proliferating cell nuclear antigen (PCNA). Ultrastructural features of cell death were examined by electron microscopy. Anti-apoptotic (Bcl-2) and pro-apoptotic (Bax, p53, CPP32 and Fas) proteins were expressed throughout the graft wall, but marked differences in the characteristics of cell death were noted between atherosclerotic and non-atherosclerotic areas of the intima. In atherosclerotic areas, pro-apoptotic proteins were widely expressed, but ultrastructural analysis failed to identify cells showing typical features of apoptosis. In these areas, necrotic cells were frequently observed, with negative correlation of Bcl-2 expression with TUNEL. Pro-apoptotic proteins showed no correlation with TUNEL. In contrast, in non-atherosclerotic areas of vein grafts, the expression of both anti-apoptotic (Bcl-2) and pro-apoptotic proteins (p53, Bax and CPP32) correlated with TUNEL. In atherosclerotic areas, non-atherosclerotic intimal areas, and in the underlying media, the numbers of TUNEL+ cells correlated with PCNA positivity. Ultrastructurally, apoptotic bodies and features of necrosis were observed in non-atherosclerotic areas of grafts. The present observations indicate that in atherosclerotic areas, cell death occurs mainly by necrosis, while in non-atherosclerotic areas, cell death occurs by both necrosis and apoptosis. An imbalance between DNA fragmentation and DNA synthesis may contribute to graft instability and failure.

Aged↗
PubMed2001

Adaptive independent component analysis of multichannel electrogastrograms.

The electrogastrogram (EGG), a cutaneous measurement of gastric electrical activity, can be severely contaminated by endogenous biological noise sources such as respiratory signal. Therefore it is important to establish effective artifact removal methods. In this paper, a novel blind signal separation method with a flexible non-linearity is introduced and applied to extract the gastric slow wave from multichannel EGGs. Simulation results show that our algorithm is able to separate a wide range of source signals, including mixtures of Gaussian sources. On real data, we demonstrate the successful applications of our procedure to extract the gastric slow wave from multichannel EGGs. As a result, the extracted clean gastric slow wave can be used to facilitate further analysis, e.g. as a reference signal for multichannel adaptive enhancement of the EGG.

Algorithms↗
PubMed2001

Decreased bone anabolic effect of basic fibroblast growth factor at fatty marrow sites in ovariectomized rats.

The purpose of the study was to compare the bone anabolic effects of basic fibroblast growth factor (bFGF) at hematopoietic (red) and fatty (yellow) marrow sites in ovariectomized (ovx) rats. Female Sprague Dawley rats were subjected to ovariectomy or sham surgery at 3 months of age and maintained untreated for 2 months after surgery. Three groups of ovx rats were then injected intravenously with bFGF for 14 days at a dose of 200 microg/kg body weight. One group of bFGF-treated OVX rats was killed at the end of the treatment period, whereas the other two groups were killed at 7 or 14 days after withdrawal of bFGF treatment. Another group of ovx rats and a group of sham-operated control rats were treated intravenously with vehicle alone for 14 days. The proximal tibia and first lumbar vertebra, bone sites with hematopoietic marrow, as well as the distal tibia and caudal vertebra, bone sites with primarily fatty marrow, were processed undecalcified for quantitative bone histomorphometry. At the hematopoietic marrow sites, bFGF treatment induced a marked accumulation of osteoid, which calcified during the withdrawal period to result in a significant increase in cancellous bone volume. Osteoblast and osteoid surfaces were increased by at least a factor of 10 at these sites in bFGF-treated ovx rats before declining rapidly during the withdrawal period. In contrast, osteoid volume was negligible in the fatty marrow sites of bFGF-treated ovx rats. Although these animals exhibited a nonsignificant trend for increased cancellous bone volume in the fatty distal tibia during the withdrawal period, no such trend was observed in the fatty caudal vertebra. Indices of bone formation (osteoblast and osteoid surfaces) were significantly increased by bFGF treatment in the fatty distal tibia, which retained some small pockets of hematopoietic cells, but not to the same great extent as in the skeletal sites with hematopoietic marrow. Furthermore, not even a trend for increased osteoblast and osteoid surfaces was observed in the fatty caudal vertebra of bFGF-treated ovx rats. These findings indicate that bFGF is a strong bone anabolic agent at skeletal sites with hematopoietic marrow, but the stimulatory effects of the growth factor on bone formation are greatly attenuated at fatty marrow sites.

Adipose Tissue↗
PubMed2001

Increased Septoria musiva resistance in transgenic hybrid poplar leaves expressing a wheat oxalate oxidase gene.

A cDNA clone of a wheat germin-like oxalate oxidase (OxO) gene regulated by the constitutive CaMV 35S promoter was expressed in a hybrid poplar clone, Populus x euramericana ('Ogy'). Previous studies showed that OxO is likely to play an important role in several aspects of plant development, stress response, and defense against pathogens. In order to study this wheat oxalate oxidase gene in woody plants, the expression of this gene and the functions of the encoded enzyme were examined in vitro and in vivo in transgenic 'Ogy'. The enzyme activity in the transformed 'Ogy' was visualized by histochemical assays and in SDS-polyacrylamide gels. It was found that the wheat OxO gene is expressed in leaves, stems, and roots of the transgenic 'Ogy' plants and the encoded enzyme is able to break down oxalic acid. Transgenic 'Ogy' leaves were more tolerant to oxalic acid as well as more effective in increasing the pH in an oxalic acid solution when compared to untransformed controls. In addition, when leaf disks from 'Ogy' plants were inoculated with conidia of the poplar pathogenic fungus Septoria musiva, which produces oxalic acid, the OxO-transformed plants were more resistant than the untransformed controls.

Ascomycota↗
PubMed2001

The role of surface ig binding in the activation of human B cells by phosphorothioate oligodeoxynucleotides.

Phosphorothioate oligodeoxynucleotides (sODNs) can induce T-cell-independent polyclonal activation of human B cells by a mechanism that depends on both sequence and back-bone structure. Because matrix-bound as well as soluble sODNs are mitogenic, this stimulation may result from the engagement of surface receptor(s). In order to investigate whether surface immunoglobin (Ig) could be a receptor for sODNs, the interaction of sODNs-fluorescein isothiocyanate (FITC) with Ig-coated beads was examined. sODNs specifically bound to human IgM and IgG. Moreover, binding of sODN to human B cells induced temperature-dependent capping of bound receptors and colocalization of FITC-sODN and IgM into aggregated caps on the surface of human B cells. A role of surface Ig was furthermore shown by observations that antibody-mediated capping of B-cell surface IgM or IgD inhibited subsequent binding of sODNs and that the capacity of sODN to stimulate human B cells was blocked by excess IgM or IgG, by nonstimulatory antibodies to sIgM, as well as by a variety of negatively charged molecules. Together, these results indicate that sODNs engage surface Ig by charge-charge interactions that lead to activation of human B cells.

Adult↗
PubMed2001

Accuracy of mandibular cross-sectional imaging with tuned- aperture computed tomography (TACT), iteratively reconstructed TACT, and multidirectional, linear, and transverse panoramic tomography.

OBJECTIVE: This study was designed to compare 5 modalities with respect to accuracy in mandibular cross-sectional imaging. The modalities tested were tuned-aperture computed tomography (TACT), iteratively reconstructed TACT, multidirectional tomography, linear tomography, and transverse panoramic tomography. STUDY DESIGN: Twenty sites were selected from 3 dry human mandibles, and cross-sectional views were imaged through use of each of the 5 modalities. A quantitative analysis included measurements of 2 linear distances; a qualitative study included image evaluation by 6 observers. A nested mixed analysis of variance model was used to control for mandibles and locations within mandibles for the quantitative analysis; the Cochran-Mantel-Haenszel test was used for the qualitative analysis. RESULTS: There was a significant difference in measurement error for maximum height but not for width. There was also a significant difference in qualitative image evaluation results. CONCLUSIONS: Of the 5 modalities tested, the narrow-layer multidirectional tomographic technique produced the greatest diagnostic accuracy and quality in cross-sectional imaging. The transverse panoramic tomographic technique produced the least diagnostic accuracy and quality. Linear tomography, TACT, and iteratively reconstructed TACT were intermediate in accuracy and quality.

Analysis of Variance↗
PubMed2001

Saikosaponin v-1 from roots of Bupleurum chinense DC.

Three triterpenoidal saponins, saikosaponin v-1(1), 6"-O-acetyl-saikosaponin b2 (2) and 6"-O-acetyl-saikosaponin d(3) were isolated from the roots of the title plant and the structures were identified on the basis of spectral analysis. Saikosaponin v-1 is a new compound, which was identified as 3beta,16alpha,23,28-tetrahydroxy-olean-11,13(18)-dien-30-oic acid-3-O-beta-D-glucopyranosyl-(1-->3)-beta-D-fucopyranosyl-30-O-xylitol ester.

Adjuvants, Immunologic↗
PubMed2001

Method development and validation for the determination of various sulfur-containing anions and other anions in the corrosion process by capillary ion electrophoresis with indirect detection.

A method of capillary ion electrophoresis with indirect detection is developed for the simultaneous determination of the sulfur-containing anions S2O4(2-), S2O3(2-), SO4(2-), SO3(2-), and S2- and other anions (Cl-, Br-, NO2-, NO3-, (COO)2(2-), F-, and PO4(3-)) in the corrosion process. The effects of pH, tetradecyltrimethylammonium hydroxide, chromate, 2-[n-cyclohexylamino]-ethane sulfonate, calcium gluconate, and acetonitrile on the migration and resolution of the anions and the stability of sulfur-containing anions are systematically investigated. The detection limits, repeatability, and linearity for the anions are comparatively studied at 374, 274, and 254 nm, and the results show that 374 nm is the optimal length. The simultaneous multiwavelength detection at 374, 254, 214, and 195 nm can assist in confirming the identification of UV-absorbing anions.

Journal Article↗
PubMed2001

Codon optimization of gene fragments encoding Plasmodium falciparum merzoite proteins enhances DNA vaccine protein expression and immunogenicity in mice.

In contrast to conventional vaccines, DNA and other subunit vaccines exclusively utilize host cell molecules for transcription and translation of proteins. The adenine plus thymine content of Plasmodium falciparum gene sequences (approximately 80%) is much greater than that of Homo sapiens (approximately 59%); consequently, codon usage is markedly different. We hypothesized that modifying codon usage of P. falciparum genes encoded by DNA vaccines from that used by the parasite to those resembling mammalian codon usage would lead to increased P. falciparum protein expression in vitro in mouse cells and increased antibody responses in DNA-vaccinated mice. We synthesized gene fragments encoding the receptor-binding domain of the 175-kDa P. falciparum erythrocyte-binding protein (EBA-175 region II) and the 42-kDa C-terminal processed fragment of the P. falciparum merozoite surface protein 1 (MSP-1(42)) using the most frequently occurring codon in mammals to code for each amino acid, and inserted the synthetic genes in DNA vaccine plasmids. In in vitro transient-expression assays, plasmids containing codon-optimized synthetic gene fragments (pS plasmids) showed greater than fourfold increased protein expression in mouse cells compared to those containing native gene fragments (pN plasmids). In mice immunized with 0.5, 5.0, or 50 microg of the DNA plasmids, the dose of DNA required to induce equivalent antibody titers was 10- to 100-fold lower for pS than for pN plasmids. These data demonstrate that optimizing codon usage in DNA vaccines can improve protein expression and consequently the immunogenicity of gene fragments in DNA vaccines for organisms whose codon usage differs substantially from that of mammals.

Animals↗
PubMed2001

E(f)-current contributes to whole-cell calcium current in low calcium in frog sympathetic neurons.

Because Ca(2+) plays diverse roles in intracellular signaling in neurons, several types of calcium channels are employed to control Ca(2+) influx in these cells. Our experiments focus on resolving the paradox of why whole-cell current has not been observed under typical recording conditions for one type of calcium channel that is highly expressed in frog sympathetic neurons. These channels, referred to as E(f)-channels, are present in the membrane at a density greater than the channels that carry approximately 90% of whole-cell current in low Ba(2+); but, E(f)-current has not been detected in low Ba(2+). Using Ca(2+) instead of Ba(2+) as the charge carrier, we recorded a possible E-type current in frog sympathetic neurons. The current was resistant to specific blockers of N-, L-, and P/Q-type calcium channels but was more sensitive to Ni(2+) block than was N- or L-current. Current amplitude in Ca(2+) is slightly greater than that in Ba(2+). In 3 mM Ca(2+), the current contributed approximately 12% of total current at peak voltage and increased at voltages more hyperpolarized to the peak, reaching approximately 40% at -30 mV, where whole-cell current starts to activate. The presence of E(f)-current in 3 mM Ca(2+) suggests a potential role for E(f)-channels in regulating calcium influx into sympathetic neurons.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2001

Induction of biologically active antibodies in mice, rabbits, and monkeys by Plasmodium falciparum EBA-175 region II DNA vaccine.

BACKGROUND: Plasmodium falciparum merozoites bind to and invade human erythrocytes via specific erythrocyte receptors. This establishes the erythrocytic stage of the parasite life cycle that causes clinical disease resulting in 2-3 million deaths per year. We tested the hypothesis that a Plasmodium falciparum ligand, EBA-175 region II (RII), which binds its erythrocyte receptor glycophorin A during invasion, can be used as an immunogen to induce antibodies that block the binding of RII to erythrocytes and thereby inhibit parasite invasion of erythrocytes. Accordingly, we immunized mice, rabbits, and monkeys with DNA plasmids that encoded the 616 amino acid RII. MATERIALS AND METHODS: DNA vaccine plasmids that targeted the secretion of recombinant RII protein with and without the universal T-cell helper epitopes P2P30 were used to immunize mice, rabbits, and Aotus monkeys. RII specific antibodies were assessed by IFA, ELISA, blocking of native [35S] labeled EBA-175 binding to human erythrocytes, and growth inhibition assays, all in vitro. RESULTS: The RII DNA plasmids were highly immunogenic as measured by ELISA and IFA. The anti-RII antibodies blocked the binding of native EBA-175 to erythrocytes, and rosetting of erythrocytes on COS-7 cells expressing RII. Most important, murine and rabbit anti-RII antibodies inhibited the invasion of merozoites into erythrocytes. We immunized nonhuman primates and showed that the RII-DNA plasmids were immunogenic and well tolerated in these monkeys. Monkeys were challenged with parasitized erythrocytes; one of three monkeys that received RII DNA plasmid was protected from fulminant disease. After challenge with live parasites, anti-RII antibody titers were boosted in the immunized monkeys. CONCLUSIONS: By proving the hypothesis that anti-RII antibodies can block merozoite invasion of erythrocytes, these studies pave the way for the clinical evaluation of EBA-175 as a receptor-blockade vaccine.

Animals↗
PubMed2001

[Study on the epidemic characteristics and burden of injuries among inhabitants in Shenzhen].

OBJECTIVE: To understand of characteristics and burden of injuries in people living in Shenzhen. METHODS: A cluster sample on the condition was conducted through house hold questionnaire administration among 11,576 inhabitant during the period of December 1999 to 2000 in Shenzhen city, Guangdong province. RESULTS: The overall incidence of injuries was 7.07%. Accident, fallings, collision wounds were the first three injures. The standard mortality of injuries was 54.13/10(5). The burden of person family and society were hospital fee-for-service induce unemployment, and so on. Mind burden gave priority to be down in spirits, it occupied to 31.62%. CONCLUSIONS: The incidence of injury were higher in Shenzhen inhabitant, and its burden be weighter, and the incidence of inhabitant with temporary cards was higher than inhabitants with resident cards. Therefore it is very important that prevention and control of injury would be enhancing.

Adult↗
PubMed2001

Inhibitory role of GDP on saikosaponin (I) stimulated enzymes secretion and rising of [Ca2+]i in rat pancreatic acini.

AIM: To study the role of guanosine diphosphate (GDP) on enzyme secretion and rising of [Ca2+]i in saikosaponin (I) [SA(I)] stimulated rat pancreatic acini. METHODS: Cell membrane of isolated rat pancreatic acini were permeabilized using streptolysin O (SLO). Enzymes secretions were indicated by detecting total protein secretions. Intracellular Ca2+ ([Ca2+]i) was measured using Fluo-3 in SPEX spectrofluorimeter. RESULTS: The inhibition of GDP on SA(I) stimulated enzymes secretion increased with increasing GDP concentration. There were two peaks in the time course of increase in [Ca2+]i evoked by SA(I) 10 micromol/L. After adding GDP 5 mmol/L, [Ca2+]i rose gradually without the two peaks. In permeabilized acini, the accumulation of enzymes stimulated by SA(I) in 30 min reduced by 57 % compared with intact acini. GDP 5 mmol/L decreased the initial rate of secretion. CONCLUSION: Inhibition of GDP on increase in [Ca2+]i reduces SA(I) stimulated enzymes secretion in pancreatic acini.

Animals↗