Biomedical subjects

L Liao

Publications and source records attributed to L Liao.

At least 19 recordsLinked to original sources

PubMed2001

Seroprevalence of Borna disease virus in domestic animals in Xinjiang, China.

To investigate the animals infected with Borna disease virus (BDV) in Xinjiang, China, we examined for BDV antibodies in the sera from groups of 20 horses, sheep and cattle, and from 165 wild rodents (18 species) by ELISA and immunoblot. The serological study disclosed the presence of antibodies to both BDV-p24 and -p40 in the horses (20%) and sheep (25%), whereas no apparent positive reaction was detected either in cattle or rodents. The results suggested that BDV is prevalent in horses and sheep in the district investigated.

Animals↗

PubMed2001

Transforming growth factor-beta(1) stimulates L-arginine transport and metabolism in vascular smooth muscle cells: role in polyamine and collagen synthesis.

BACKGROUND: Transforming growth factor-beta(1) (TGF-beta(1)) contributes to arterial remodeling by stimulating vascular smooth muscle cell (VSMC) growth and collagen synthesis at sites of vascular injury. Because L-arginine is metabolized to growth-stimulatory polyamines and to the essential collagen precursor L-proline, we examined whether TGF-beta(1) regulates the transcellular transport and metabolism of L-arginine by VSMCs. METHODS AND RESULTS: TGF-beta(1) increased L-arginine uptake, and this was associated with a selective increase in cationic amino acid transporter-1 (CAT-1) mRNA. In addition, TGF-beta(1) stimulated L-arginine metabolism by inducing arginase I mRNA and arginase activity. TGF-beta(1) also stimulated L-ornithine catabolism by elevating ornithine decarboxylase (ODC) and ornithine aminotransferase (OAT) activity. TGF-beta(1) markedly increased the capacity of VSMCs to generate the polyamine putrescine and L-proline from extracellular L-arginine. The TGF-beta(1)-mediated increase in putrescine and L-proline production was reversed by methyl-L-arginine, a competitive inhibitor of cationic amino acid transport, or by hydroxy-L-arginine, an arginase inhibitor. Furthermore, the formation of putrescine was inhibited by the ODC inhibitor alpha-difluoromethylornithine, and L-proline generation was blocked by the OAT inhibitor L-canaline. L-Canaline also inhibited TGF-beta(1)-stimulated type I collagen synthesis. CONCLUSIONS: These results demonstrate that TGF-beta(1) stimulates polyamine and L-proline synthesis by inducing the genes that regulate the transport and metabolism of L-arginine. In addition, they show that TGF-beta(1)-stimulated collagen production is dependent on L-proline formation. The ability of TGF-beta(1) to upregulate L-arginine transport and direct its metabolism to polyamines and L-proline may contribute to arterial remodeling at sites of vascular damage.

Animals↗

PubMed2001

Treatment of no-reflow and impaired flow with the nitric oxide donor nitroprusside following percutaneous coronary interventions: initial human clinical experience.

OBJECTIVES: The objective of this study was to test the hypothesis that the intracoronary administration of a direct donor of nitric oxide is a safe and effective method to treat impaired blood flow (no-reflow phenomenon) that occurs during percutaneous transluminal coronary interventions (PTCI). BACKGROUND: The absence of blood flow or decreased blood flow in a coronary artery following PTCI despite the presence of a patent epicardial vessel or graft is designated "no-reflow" or "impaired flow." This alteration in blood flow is a serious complication of percutaneous revascularization strategies that results in an increased incidence of morbidity, myocardial infarction and mortality. METHODS: Nineteen consecutive patients undergoing standard percutaneous revascularization procedures complicated by either no-reflow or impaired flow that received intracoronary nitroprusside treatment were studied. One patient had two procedures performed on two separate grafts on two successive days. Interventions were performed on either saphenous vein grafts or native vessels and utilized angioplasty, stent deployment or rotational atherectomy strategies. Following interventions that were associated with impaired flow, varying total doses (of nitroprusside 50 to 1,000 microg) were administered into the coronary artery or saphenous vein graft. The angiographic archives before and after intracoronary administration of nitroprusside were analyzed for TIMI grade flow and a frame count method was used to quantitate blood flow velocity. RESULTS: Following a PTCI that resulted in either no-reflow or impaired flow, nitroprusside (median dose 200 microg) was found to lead to a highly significant and rapid improvement in both angiographic flow (p < 0.01 compared with pretreatment angiogram) and blood flow velocity (p < 0.01 compared with pretreatment angiogram). No significant hypotension or other adverse clinical events were associated with nitroprusside administration. CONCLUSIONS: The direct nitric oxide donor nitroprusside is an effective, safe treatment of impaired blood flow and no-reflow associated with PTCI. The use of nitroprusside to treat syndromes secondary to microvascular dysfunction may provide a novel therapeutic strategy for treating no-reflow or impaired blood flow following percutaneous interventions.

Aged↗

PubMed2001

Possible atypical cross-sensitivity between phenytoin and carbamazepine in the anticonvulsant hypersensitivity syndrome.

Anticonvulsant hypersensitivity syndrome (AHS) is a rare but potentially life-threatening reaction that occurs in response to common anticonvulsants in predisposed individuals. It is often characterized by fever, rash, lymphadenopathy, hepatitis, and laboratory abnormalities. Consequently, it often is overlooked or even misdiagnosed by practitioners unfamiliar with AHS. Cross-sensitivity manifests frequently between phenytoin, phenobarbital, and carbamazepine as an exacerbation of presenting signs and symptoms. We report a case of AHS in a patient whose clinical features changed significantly when switching from phenytoin to carbamazepine. Physicians and pharmacists must become aware of the extreme variability in AHS manifestation so that the offending anticonvulsant regimen can be discontinued in a timely manner.

Aged↗

PubMed2000

The steroid receptor coactivator SRC-3 (p/CIP/RAC3/AIB1/ACTR/TRAM-1) is required for normal growth, puberty, female reproductive function, and mammary gland development.

Steroid receptor coactivator-3 (SRC-3) is a coactivator of nuclear receptors in the SRC family as assayed in vitro. Here, we show that mouse SRC-3 is expressed in a tissue-specific fashion and distributed mainly in the oocytes, mammary glands, hippocampus, olfactory bulb, smooth muscle, hepatocytes, and vaginal epithelium. Genetic disruption of SRC-3 in mice results in a pleiotropic phenotype showing dwarfism, delayed puberty, reduced female reproductive function, and blunted mammary gland development. Hormonal analysis indicates that SRC-3 plays a role in both the growth hormone regulatory pathway and the production of estrogen, which may explain the observed phenotypes. These results suggest that the physiological role of SRC-3 is different from that of SRC-1 and prove the diversity among coactivator family members.

Animals↗

PubMed2000

Immunoglobulin isotype determines pathogenicity in antibody-mediated myocarditis in naïve mice.

Antimyosin reactivity is associated with cardiac damage in autoimmune myocarditis, an inflammatory heart disease characterized by a cellular infiltrate in the myocardium and myocyte necrosis. We are interested in the pathogenicity of antimyosin antibodies and their ability to cause autoimmune myocarditis. We have shown that antimyosin antibodies of the IgG isotype will induce disease in the DBA/2 mouse. In the present study, we show that IgM antimyosin antibodies do not induce myocarditis; however, these same antibodies become pathogenic when converted to the IgG isotype. Although IgM antibodies can penetrate the myocardium during cardiac inflammation, they are usually less able to leave the vascular compartment and penetrate cardiac tissue, thus accounting for their lack of pathogenicity. Thus, antimyosin B cells may be potentially pathogenic only after antigen activation and heavy chain class switching or under conditions that alter vascular permeability in the heart.

Animals↗

PubMed2000

Physiological cyclic stretch directs L-arginine transport and metabolism to collagen synthesis in vascular smooth muscle.

Application of cyclic stretch (10% at 1 hertz) to vascular smooth muscle cells (SMC) increased L-arginine uptake and this was associated with a specific increase in cationic amino acid transporter-2 (CAT-2) mRNA. In addition, cyclic stretch stimulated L-arginine metabolism by inducing arginase I mRNA and arginase activity. In contrast, cyclic stretch inhibited the catabolism of L-arginine to nitric oxide (NO) by blocking inducible NO synthase expression. Exposure of SMC to cyclic stretch markedly increased the capacity of SMC to generate L-proline from L-arginine while inhibiting the formation of polyamines. The stretch-mediated increase in L-proline production was reversed by methyl-L-arginine, a competitive inhibitor of L-arginine transport, by hydroxy-L-arginine, an arginase inhibitor, or by the ornithine aminotransferase inhibitor L-canaline. Finally, cyclic stretch stimulated collagen synthesis and the accumulation of type I collagen, which was inhibited by L-canaline. These results demonstrate that cyclic stretch coordinately stimulates L-proline synthesis by regulating the genes that modulate the transport and metabolism of L-arginine. In addition, they show that stretch-stimulated collagen production is dependent on L-proline formation. The ability of hemodynamic forces to up-regulate L-arginine transport and direct its metabolism to L-proline may play an important role in stabilizing vascular lesions by promoting SMC collagen synthesis.

Amino Acid Transport Systems, Basic↗

PubMed2000

Genetic linkage mapping of zebrafish genes and ESTs.

Genetic screens in zebrafish (Danio rerio) have isolated mutations in hundreds of genes essential for vertebrate development, physiology, and behavior. We have constructed a genetic linkage map that will facilitate the identification of candidate genes for these mutations and allow comparisons among the genomes of zebrafish and other vertebrates. On this map, we have localized 771 zebrafish genes and expressed sequence tags (ESTs) by scoring single-stranded conformational polymorphisms (SSCPs) in a meiotic mapping panel. Of these sequences, 642 represent previously unmapped genes and ESTs. The mapping panel was comprised of 42 homozygous diploid individuals produced by heat shock treatment of haploid embryos at the one-cell stage (HS diploids). This "doubled haploid" strategy combines the advantages of mapping in haploid and standard diploid systems, because heat shock diploid individuals have only one allele at each locus and can survive to adulthood, enabling a relatively large quantity of genomic DNA to be prepared from each individual in the mapping panel. To integrate this map with others, we also scored 593 previously mapped simple-sequence length polymorphisms (SSLPs) in the mapping panel. This map will accelerate the molecular analysis of zebrafish mutations and facilitate comparative analysis of vertebrate genomes.

Animals↗

PubMed2000

T-Cell-dependent antibody response to the dominant epitope of streptococcal polysaccharide, N-acetyl-glucosamine, is cross-reactive with cardiac myosin.

Autoantibodies against myosin are associated with myocarditis and rheumatic heart disease. In this study, the antigenic cross-reactivity of myosin and N-acetyl-glucosamine (GlcNAc), the dominant epitope of Group A streptococcal polysaccharide, was examined. Six antimyosin monoclonal antibodies (MAbs) derived from mice with cardiac myosin-induced myocarditis were characterized. All MAbs cross-reacted with GlcNAc, mimicking a subset of MAbs derived from rheumatic carditis patients that bind both myosin and streptococcal polysaccharide. Variable (V) region gene usage was diverse, with five of six MAb heavy-chain V regions encoded by distinct members of the J558 family and the sixth encoded by a member of the VGAM3.8 family. Light-chain V-region segments were derived from the Vk1, Vk4/5, Vk10, and Vk21 families. These antimyosin, anti-GlcNac MAbs demonstrated several T-cell-dependent features: they were predominantly immunoglobulin G, were encoded by V-region genes expressed late in development, and displayed somatic mutation. A direct correlation between the extent of somatic mutation and the affinity for myosin was observed. Affinity for GlcNAc also increased with the frequency of mutation, demonstrating that affinity maturation can occur simultaneously for both self antigen and foreign antigen. Based on these observations, we immunized mice with GlcNAc coupled to bovine serum albumin and demonstrated that a T-cell-dependent response to GlcNAc leads to antimyosin reactivity. We speculate that the pathogenic antibody response in rheumatic carditis may reflect the conversion of a T-cell-independent response to GlcNAc to a T-cell-dependent cross-reactive response to GlcNAc and myosin.

Acetylglucosamine↗

PubMed2000

A preliminary study of single nucleotide polymorphisms of lipoprotein lipase gene in coronary atherosclerotic heart disease.

OBJECTIVE: This study inquired into the relationship between single nucleotide polymorphisms(SNPs) of lipoprotein lipase gene (LPL) and coronary atherosclerotic heart disease(CHD). METHODS: Exon 6 and fragment of intron 6 in LPL gene from 102 cases of CHD and 110 normal subjects were analysed by polymerase chain reaction amplification, temperature-modulated high-performance liquid chromatography (TmHPLC) and DNA sequencing. RESULTS: Three new SNPs (4212t/c, 4509t/c, 4576a/c) were detected in the intron 6 of LPL gene. There was significant difference in frequencies of 4212t/c, and 4576a/c between health group and CHD group(P<0.05). CONCLUSION: This study has accumulated additional data on SNPs in LPL gene and provided new data for exploring the mechanism of CHD.

Adult↗

PubMed2000

Analysis of temperature-modulated high-performance liquid chromatography as a tool for detection of single nucleotide polymorphism.

OBJECTIVE: To establish and evaluate temperature-modulated high-performance liquid chromatography(TmHPLC) as a rapid and efficient technique of detecting single nucleotide polymorphism(SNP). METHODS: Several TmHPLC parameters, such as the eluting gradient ranges and column temperatures used for analysing the amplicons have been studied. The size of DNA fragments suitable for analysis of SNP was studied. Also the sensitivity of the TmHPLC was evaluated. RESULTS: The suitable chromatographic condition of TmHPLC was found out. The elution peaks of dNTP and primers could be separated from those of polymerase chain reaction products of the genomic DNA. The heterozygotes of SNP from the sequenced DNA fragment with 178bp, 269bp and 272bp could be distinguished from the homozygotes of SNP clearly. CONCLUSION: The authors have established and evaluated the TmHPLC method, which is an efficient, sensitive and rapid method for screening out SNP in the DNA fragments of larger size.

Chromatography, High Pressure Liquid↗

PubMed2000

[Genetic polymorphism of 10 STR loci on chromosome 9 and its forensic application in Chinese population].

OBJECTIVE: To have a thorough knowledge of the genetic polymorphism of 10 short tandem repeats loci of chromosome 9 in Chinese population and its application in forensic science. METHODS: The 9 STR tetrameric loci and one trimeric tandem repeat locus were chosen from Genome Databank. Eighty-three EDTA-blood samples were collected from the unrelated family in Baiyin city, Gansu province. DNA was extracted by Chelex method and amplified by the polymerase chain reaction(PCR). The PCR products were analyzed by PAGE electrophoresis. RESULTS: The polymorphisms of all 10 STR loci have been obtained in Chinese Han population. The 10 STR loci follow the Mendel ns law. CONCLUSION: The data of all 10 STR loci is beneficial to understanding the population genetics of them in Chinese Han population.

Chromosomes, Human, Pair 9↗

PubMed1999

Integrated mapping package--a physical mapping software tool kit.

We have developed an integrated physical mapping computer software package (IMP), originally designed to support the physical mapping of human chromosome 13 and expanded to support several gene-identification projects based on the positional candidate approach. IMP displays map data in a form that provides useful guidelines to the end users. An integrated map with high resolution and confidence is constructed from different types of mapping data, including hybridization experiments, STS-based PCR assays, genetic linkage mapping, cDNA localization, and FISH data. The map is also designed to provide suggestions for specific experiments that are required to obtain maps with even higher resolution and confidence. To this end, the optimization employs multiple constraints that take into account already established STS "scaffold" maps. This software thus serves as an important general tool kit for physical mapping, sequencing, and gene-hunting projects.

Algorithms↗

PubMed1999

Detection of circulating antigens and antibodies in Toxocara canis infection among children in Chengdu, China.

In order to determine the seroprevalence of Toxocara spp. infection in children from Chengdu, we performed an enzyme-linked immunosorbent assay (ELISA) and sandwich ELISA (S-ELISA) with excretory-secretory antigens isolated from second-stage larvae of Toxocara canis (TES-Ag ELISA). The seroprevalences of T. canis antibodies in the children from rural areas, urban districts, and urban districts with recent Ascaris lumbricoides infection were 17.7% (59/333), 2.1% (4/186), and 2.6% (1/38), respectively. Among 63 suspected patients with symptoms of T. canis infection, 31 had positive antibodies. The inhibition assay showed an apparent inhibiting capacity of TES-Ag for the antibody against T. canis larvae. The result of S-ELISA demonstrated that circulating antigens of T. canis larvae could be detected in part of the serum with positive antibodies and that the detection rate for circulating antigens in the sera could be improved by polyethylene glycol-acid treatment. This is the first epidemiological study to confirm the existence of T. canis infection and Toxocara-larvae migrans in Chengdu by the combination of TES-Ag ELISA and S-ELISA.

Animals↗

PubMed1999

A method for isolation and purification of nematode larvae.

A new apparatus for isolating, purifying, and collecting larvae of nematodes is described. Results of collecting larvae with Baermann's traditional method and the pasteur pipette cotton plug method are compared to those obtained with the device in this research note. It is simple, easy to use, and a more effective apparatus for the isolation, purification, and collection of nematode larvae.

Animals↗

PubMed1998

Thrombin stimulates vascular smooth muscle cell polyamine synthesis by inducing cationic amino acid transporter and ornithine decarboxylase gene expression.

Thrombin, a serine protease, is a potent mitogen for vascular smooth muscle cells (SMCs), but its mechanism of action is not known. Since L-ornithine is metabolized to growth-stimulatory polyamines, we examined whether thrombin regulates the transcellular transport and metabolism of L-ornithine by vascular SMCs. Treatment of SMCs with thrombin initially (0 to 2 hours) decreased L-ornithine uptake, whereas longer exposures (6 to 24 hours) progressively increased transport. Kinetic studies indicated that thrombin-induced inhibition was associated with a decrease in affinity for L-ornithine, whereas stimulation was mediated by an increase in transport capacity. Thrombin induced the expression of both cationic amino acid transporter (CAT)-1 and CAT-2 mRNA. Furthermore, thrombin stimulated L-ornithine metabolism by inducing ornithine decarboxylase (ODC) mRNA expression and activity. The stimulatory effect of thrombin on both L-ornithine transport and ODC activity was reversed by hirudin, a thrombin inhibitor, and was mimicked by a 14-amino acid thrombin receptor-activating peptide. Thrombin also markedly increased the capacity of SMCs to generate putrescine, a polyamine, from extracellular L-ornithine. The thrombin-mediated increase in putrescine production was reversed by N(G)-methyl-L-arginine, a competitive inhibitor of cationic amino acid transport, or by alpha-difluoromethylornithine (DFMO), an ODC inhibitor. DFMO also inhibited thrombin-induced SMC proliferation. These results demonstrate that thrombin stimulates polyamine synthesis by inducing CAT and ODC gene expression and that thrombin-stimulated SMC proliferation is dependent on polyamine formation. The ability of thrombin to upregulate L-ornithine transport and direct its metabolism to growth-stimulatory polyamines may contribute to postangioplasty restenosis and atherosclerotic lesion formation.

Amino Acid Transport Systems, Basic↗

PubMed1998

[A longitudinal study on growth model and velocity of term small for gestation age].

To probe into the vegetal pattern and find out the key period of promoting normal growth of term small for gestational age (TSGA), a longitudinal study on growth model and velocity of TSGA was conducted from Jan 1993 to June 1997. The body weight and length of 150 children of TSGA (57 boys, 93 girls) and 152 children as controls (58 boys, 94 girls) were measured from the 1st month to 36th month. The growth model was analysed by multilevel models. The result showed that there was a difference between the growth models of TSGA and controls. During 8 and a half months (center month), the weight, length of controls were 1.19 kg, 3.46 cm greater than those of TSGA; the weight, length of boys were 0.34 kg, 1.08 cm more than those of girls respectively. The growth velocity of TSGA was similar to that of controls. The maximal growth velocity was observed during the first 6 monthes after birth. The order of growth velocity from high to low was 1 mo. > 2 mo. > 3 mo. in length and weight, showing that children of TSGA have their own growth model. Their growth velocity should be monitored attentively. If low velocity appears one should search for the cause and adopt apropriate measures to ensure their growth in accordance with their "own track".

Body Height↗

PubMed1998

[Determination and significance of nitric oxide and tumor necrosis factor-alpha induced by peripheral blood monocyte in vitro in patients with malignant bone tumors].

Peripheral blood monocytes from 15 cases of malignant bone tumors and 12 cases of health volunteers were seperated and induced by lipopolysaccharide(LPS) for 48-hour culture. The supernatant was collected for determining the content of nitrite and tumor necrosis factor-alpha(TNF-alpha) (by Griess and ELISA methods, respectively). The results were as follows: The content of nitrite and TNF-alpha in patients with malignant bone tumors was significantly higher than that in normal control; the content of nitrite and TNF-alpha in the malignant bone tumor group presented the positive correlation (r = 0.8909, P < 0.01). The results suggest that NO and TNF-alpha produced by activated macrophages may be related to the pathogenesis of malignant bone tumors.

Adolescent↗