Biomedical subjects

L Liao

Publications and source records attributed to L Liao.

At least 19 recordsLinked to original sources

PubMed2003

Luciferase expression controlled by a viral gene promoter in a mammalian circadian pacemaker.

Retinal light exposure induces several immediate-early genes in the hypothalamic suprachiasmatic nucleus (SCN), which contains the major circadian pacemaker of mammals. Clock-controlled and light-induced genes expressed in the SCN such as c- and contain upstream regulatory elements similar to those of the major immediate-early gene (IE-1) of the human cytomegalovirus. IE-1 expression is critical for viral reactivation from latency and increases in response to agents acting through depolarization or the cAMP response element. To test whether IE-1 could be under circadian control, bioluminescence was imaged in individual SCN cells of brain slice cultures from transgenic mice containing the IE-1 enhancer/promoter upstream from the firefly luciferase gene. A small percentage of the cells in neonatal and adult cultures displayed circadian transgene expression, particularly ones near the dorsomedial edge of the SCN. Single-cell bioluminescence imaging revealed that the circadian pacemaker can regulate exogenous viral genes and could play a role in viral diseases.

Animals↗

PubMed2001

The genome of the natural genetic engineer Agrobacterium tumefaciens C58.

The 5.67-megabase genome of the plant pathogen Agrobacterium tumefaciens C58 consists of a circular chromosome, a linear chromosome, and two plasmids. Extensive orthology and nucleotide colinearity between the genomes of A. tumefaciens and the plant symbiont Sinorhizobium meliloti suggest a recent evolutionary divergence. Their similarities include metabolic, transport, and regulatory systems that promote survival in the highly competitive rhizosphere; differences are apparent in their genome structure and virulence gene complement. Availability of the A. tumefaciens sequence will facilitate investigations into the molecular basis of pathogenesis and the evolutionary divergence of pathogenic and symbiotic lifestyles.

Agrobacterium tumefaciens↗

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

Benign intratesticular cystic lesions: US features.

Benign intratesticular lesions are rare, but recognition is important to avoid unnecessary surgical intervention. The ultrasonographic (US) features that help differentiate benign from malignant intratesticular lesions are emphasized by the authors. Benign lesions include intratesticular simple cysts, tubular ectasia, epidermoid cyst, tunica albuginea cyst, intratesticular varicocele, abscess, and hemorrhage (infarction). US features of cystic malignant neoplasms that help in differentiation of them from benign cystic lesions are also presented. The US appearance of epidermoid cysts varies with the maturation, compactness, and quantity of keratin present. Of the cystic malignant testicular tumors, which can occur anywhere in testicular parenchyma, teratomas are the most frequent to manifest as cystic masses. An abnormal rind of parenchyma with increased echogenicity usually surrounds these lesions. An intratesticular spermatocele communicates with the seminiferous tubules, whereas simple ectasia of the rete testis does not do so directly. These cysts contain spermatozoa and can be septate. The US findings of intratesticular varicocele are similar to those of extratesticular varicocele and include multiple anechoic, serpiginous, tubular structures of varying sizes. Improvements in gray-scale and Doppler US technology allow subtle distinctions between benign and malignant testicular lesions that were not possible a decade earlier.

Abscess↗

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↗

PubMed2001

[Overexpression of artificial synthetic gene of Aspergillus niger NRRL3135 phytase in Pichia pastoris].

The phytase gene of Aspergillus niger NRRL3135 was modified with a deletion of intron and signal coding sequence. Then, according to the codon preference of Pichia pastoris, modified phyA gene was artificially synthesized and cloned into expression vector of pPICZ alpha A. The recombinant plasmid was transformed into chromosome of Pichia pastoris X-33 strain by electroporation. The results of SDS-PAGE and enzymatic kinetic analysis proved that the recombinant phytase was secreted into culture medium with nearly same character of natural phytase. After screening for high level productive yeast strains, a strain named SPAN-III produced recombinant phytase with 165,000 u/mL under the condition of shake cultivation. It will satisfy the demand for industrialized production in some degree.

6-Phytase↗

PubMed2000

[Change of bone mineral density in type 2 diabetes mellitus with nephropathy].

OBJECTIVE: To investigate into the changes of bone mineral density(BMD) in Type 2 diabetes mellitus with nephropathy(DN) and without nephropathy(DM). METHODS: BMD of lumbar vertebrae 1-4 and femur in 93 cases of Type 2 diabetes mellitus(41 cases of DN and 52 cases of DM) were measured with dual energy x-ray absorptiometry(DEXA) and were compared with age, sex, and BMI-matched normal control group. RESULTS: No significant differences were found in BMD of femoral total, neck, L1-L4 between DM and normal controls in females(P > 0.05). DM in men had higher BDM at L2, femoral total neck than normal controls(P < 0.05). BMD at femoral total, neck, in females and L1-L4 femoral total neck in men in DN group were lower than DM group, but had no statistical differences. CONCLUSION: The changes in BMD of above areas in DM were normal and higher because of different areas. BMD in DN had lower predisposition.

Absorptiometry, Photon↗

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↗

PubMed2000

[Mixing of Cunninghamia lanceolata with Michelia macclurei and restoration of self-sustaining mechanism in G. lanceolata plantation].

The formation of self-sustaining mechanism is one of the major objectives for the sustainable management of plantations. In this study, the incorporation of different proportions of native Michelia macclurei into Cunninghamia lanceolata plantation was practiced to restore the degraded C. lanceolata plantation, and the comparison of nutrient cycling characteristics and soil nutrient concentrations was made among four types of plantation stand with different mixed rate of native M. macclurei representing four different restoration stages of degraded C. lanceolata plantations. With the increase of the proportion of M. macclurei in the plantation, the litterfall and returned nutrients N, P, K, Ca and Mg increased. The nutrient cycling efficiency increased significantly, e.g., that of N and Mg increased from about 0.1 for the degraded pure C. lanceolata plantation to above 0.5 for the pure M. macclurei plantation. Soil organic matter and nutrients also elevated. It is suggested that the self-sustaining mechanism of the C. lanceolata plantation forest gradually reformed as the proportion of native M. macclurei mixed in the plantation increased. The criteria to determine the proportion of native broad-leaved tree species mixed in C. lanceolata plantations for the purpose of sustainable management should be based on whether the self-sustaining mechanism was reformed and whether the soil nutrient status was improved.

Biomass↗