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Biomedical subjects

H Liang

Publications and source records attributed to H Liang.

At least 19 recordsLinked to original sources
PubMed2026

Fourier-transform infrared-based genome-wide association study identifies candidate genes and variants for sow colostrum composition.

Sows with high prolificacy and better lactation traits are beneficial for weaned piglet number. Because the genetic basis of sow lactation traits remains elusive, genetic improvement for lactation traits lags behind that for litter traits, constraining the full realisation of genetic potential for large litters. Here, we measured 1&#xa0;060 Fourier-transform infrared (FTIR) wavenumbers and five predicted colostrum composition traits from sow colostrum samples. Heritability estimates for both the FTIR spectra and predicted traits ranged from moderate to high. Correlation analysis revealed that lactose percentage was negatively genetically correlated with the other four predicted traits (fat percentage, protein percentage, total solid content, and urea nitrogen content) and with 24&#xa0;h litter weight, which was positively genetically correlated with both protein and total solid content. Genome-wide association studies on the FTIR spectra and predicted traits identified 134 significant single-nucleotide polymorphisms (SNPs) (False discovery rate < 0.05), with most clustering on Sus scrofa chromosomes (SSC) 5 and 7. Among the candidate genes, two expressed in lactating mammary tissue have established roles in milk trait determination: (1) LALBA, which encodes a major colostrum protein and is responsible for lactose synthesis, and (2) BTN1A1, which mediates milk fat secretion. Additionally, the study detected two important candidate variants on SSC7: (1) rs691487382, which was colocalised with the expression quantitative trait locus signal for TRIM26 in the liver, a key metabolic organ supporting lactation, and (2) rs327923027, a missense variant located in a phylogenetically conserved domain of TRIM26, an E3 ubiquitin ligase implicated in liver homeostasis. Taken together, this study identifies, for the first time, candidate genes and variants for sow colostrum, providing genomic markers useful for genetic improvement.

Association analysis↗
PubMed2003

Recombinant prostate specific antigen inhibits angiogenesis in vitro and in vivo.

BACKGROUND: Prostate specific antigen (PSA) is a kallikrein family member with serine protease activity commonly used as a diagnostic marker for prostate cancer. We recently described anti-angiogenic properties of PSA [Fortier et al.: JNCI 91:1635-1640]. METHODS: Two forms of PSA were cloned and expressed in Pichia pastoris: one, an intact PSA with an N-terminus of IVGGVS em leader; the second, an N-1 PSA variant. The recombinant proteins were tested for serine protease activity and for anti-angiogenic activity in vitro and in vivo. RESULTS: The rate of substrate hydrolysis by the intact recombinant PSA was similar to that of PSA isolated and purified from human seminal plasma. In contrast, the N-1 PSA variant lacked serine protease activity. In an endothelial cell migration assay, the concentration that resulted in 50% inhibition (IC(50)) was: 0.5 microM for native PSA, 0.5 microM for intact recombinant protein, and 0.1 microM for the N-1 variant PSA. Both the intact recombinant and the N-1 recombinant PSA inhibited angiogenesis in vivo. CONCLUSIONS: Purified recombinant PSA inhibits angiogenesis, proving the concept that PSA is an anti-angiogenic, and serine protease activity, as determined by synthetic substrate hydrolysis, is distinct from the anti-angiogenic properties of PSA.

Angiogenesis Inhibitors↗
PubMed2003

Multiple idiopathic cervical root resorption: systematic review and report of four cases.

OBJECTIVES: The objectives of this study were to report four cases of multiple idiopathic cervical root resorption and to systematically review the literature on this condition. METHODS: The clinical and radiographic findings and the medical/dental histories of four patients who presented with multiple idiopathic cervical root resorption were recorded. Additionally, 10 references from the literature that reported on 14 patients were reviewed. RESULTS: Multiple idiopathic cervical root resorption was an incidental finding on routine clinical and radiographic examination. There appeared to be no correlation between this type of resorption and any medical/dental finding. Radiographically, multiple idiopathic cervical root resorption was found to begin at the cemento-enamel junction and then either progress to involve the entire cervical region or, at some point, spontaneously arrest. Those cases that progressed to involve the entire cervical region required extraction. The number of teeth that demonstrated this condition ranged from 5 to 24 per patient. More teeth became involved as the condition was followed in time. There was no detectable frequency of occurrence for any particular dental region or tooth among the involved teeth. Of a total of 18 patients, 13 were females whose ages ranged from 7 years to 68 years. Ten of the 18 patients were Caucasian. CONCLUSIONS: Multiple idiopathic cervical root resorption was found most frequently associated with younger females. This condition appeared to be of unknown aetiology and uncertain natural history.

Adult↗
PubMed2001

Early intestinal Th1 inflammation and mucosal T cell recruitment during acute graft-versus-host reaction.

Little is understood about the earliest cytokine responses and the role(s) of donor CD4 T cells in the intestine during the induced graft-vs-host reaction (GVHR). We investigated the activation and mucosal homing phenotype of the donor CD4 cells and the kinetics of cytokine responses within the intestine and associated lymphoid tissues during early GVHR. Significant frequencies of donor CD4 cells accumulated within recipient Peyer's patches (PP), mesenteric lymph nodes (MLN), lamina propria (LP), and spleen (SP), during the first 9 days of GVHR. Many donor CD4 cells in SP, MLN, and LP expressed CD44 and also expressed de novo the mucosal homing integrin alpha(4)beta(7) (LPAM-1). A large IFN-gamma response occurred by day 3 in cells from PP and MLN, but much later (day 9) in SP and LP cells. IL-10 production by SP and MLN cells was elevated initially but declined substantially by day 9. IL-4 production by SP, MLN, and PP cells was low on day 3 and showed gradual decline in LP by day 9. IL-5 production by LP cells gradually increased in direct contrast to IL-5 production by MLN cells. The MLN CD4 cells showed the most dynamic changes, with high numbers of activated/effector donor CD4 cells and altered cytokine production consistent with a developing Th1 response. The IFN-gamma responses in PP and MLN preceded that of the SP, suggesting an intestinal origin for some Th1 effector cells in GVHR. Donor CD4 T cells apparently acquire the ability to home to the LP during early GVHR.

Acute Disease↗
PubMed2001

Endostatin binds tropomyosin. A potential modulator of the antitumor activity of endostatin.

The mechanism of action of Endostatin, an endogenous inhibitor of angiogenesis and tumor growth, remains unknown. We utilized phage-display technology to identify polypeptides that mimic the binding domains of proteins with which Endostatin interacts. A conformed peptide (E37) was identified that shares an epitope with human tropomyosin implicating tropomyosin as an Endostatin-binding protein. We show that recombinant human Endostatin binds tropomyosin in vitro and to tropomyosin-associated microfilaments in a variety of endothelial cell types. The most compelling evidence that tropomyosin modulates the activity of Endostatin was demonstrated when E37 blocked greater than 84% of the tumor-growth inhibitory activity of Endostatin in the B16-BL6 metastatic melanoma model. We conclude that the E37 peptide mimics the Endostatin-binding epitope of tropomyosin and blocks the antitumor activity of Endostatin by competing for Endostatin binding. We postulate that the Endostatin interaction with tropomyosin results in disruption of microfilament integrity leading to inhibition of cell motility, induction of apoptosis, and ultimately inhibition of tumor growth.

Actin Cytoskeleton↗
PubMed2001

Determination of albumin and myoglobin in dialysate and ultrafiltrate samples by high-performance size-exclusion chromatography.

A high-performance size-exclusion chromatographic method was developed, validated and implemented for simultaneous and quantitative determination of albumin and myoglobin along with inulin, vancomycin and creatinine in dialysate and ultrafiltrate samples from in vitro hemodialysis experiments. The experimental parameters including mobile phase pH, ionic strength, detection wavelength, flow-rate, injection volume were first optimized for the determination of albumin, myoglobin, inulin, vancomycin and creatinine. The peak height ratio and detection limits of the proteins were then comparatively studied at 210, 254 and 280 nm by UV and diode array detection. The method was further validated by evaluating the linearity, precision and accuracy of the proteins. The assay was finally implemented to the simultaneous and quantitative determination of the proteins in dialysate and ultrafiltrate samples.

Albumins↗
PubMed2001

Reciprocal phosphorylation and regulation of endothelial nitric-oxide synthase in response to bradykinin stimulation.

Endothelial nitric-oxide synthase (eNOS) is phosphorylated at Ser-1179 (bovine sequence) by Akt after growth factor or shear stress stimulation of endothelial cells, resulting in increased eNOS activity. Purified eNOS is also phosphorylated at Thr-497 by purified AMP-activated protein kinase, resulting in decreased eNOS activity. We investigated whether bradykinin (BK) stimulation of bovine aortic endothelial cells (BAECs) regulates eNOS through Akt activation and Ser-1179 or Thr-497 phosphorylation. Akt is transiently activated in BK-stimulated BAECs. Activation is blocked completely by wortmannin and LY294002, inhibitors of phosphatidylinositol 3-kinase, suggesting that Akt activation occurs downstream from phosphatidylinositol 3-kinase. BK stimulates a transient phosphorylation of eNOS at Ser-1179 that is correlated temporally with a transient dephosphorylation of eNOS at Thr-497. Phosphorylation at Ser-1179, but not dephosphorylation at Thr-497, is blocked by wortmannin and LY294002. BK also stimulates a transient nitric oxide (NO) release from BAECs with a time-course similar to Ser-1179 phosphorylation and Thr-497 dephosphorylation. NO release is not altered by wortmannin. BK-stimulated dephosphorylation of Thr-497 and NO release are blocked by the calcineurin inhibitor, cyclosporin A. These data suggest that BK activation of eNOS in BAECs primarily involves deinhibition of the enzyme through calcineurin-mediated dephosphorylation at Thr-497.

Androstadienes↗
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↗