Biomedical subjects

C Li

Publications and source records attributed to C Li.

At least 55 records · Page 3Linked to original sources

PubMed2005

A movement protein and three capsid proteins are all necessary for the cell-to-cell movement of apple latent spherical cheravirus.

Immunoblot analysis of apple latent spherical cheravirus (ALSV)-infected leaves using a polyclonal antibody against the 21 C-terminal amino acids of a 53 K/42 K movement protein (MP) showed that a protein with an Mr of 42 kDa (42KP) is the dominant form found in vivo, which could indicate that the second AUG is used as an initiation codon of a ORF in RNA2. Co-expression of GFP with 42KP in tobacco epidermal cells showed that 42KP is able to facilitate cell-to-cell trafficking of GFP that is expressed in the same cells. The analysis of deletion mutants on each of MP, Vp24, Vp20, or Vp25 using an ALSV vector that stably expresses GFP indicated that an MP and three capsid proteins are all indispensable for the cell-to-cell movement of the virus. In ultrathin sections of infected leaves, a file of virus-like particles passing through the plasmodesmata connecting neighboring cells and tubular structures containing virus-like particles extending into the cytoplasm were observed. These results show that ALSV moves from cell to cell as virus particles.

Blotting, Western↗

PubMed2005

Site-specific H/D exchange of p-methoxyphenol studied by resonant two-photon ionization and mass-analyzed threshold ionization spectroscopy.

The origin of the S(1) <-- S(0) transition (E(1)) and the adiabatic ionization energy (IE) of cis-p-methoxyphenol-d(1)-OD are determined to be 33 660 and 62 302 cm(-1), whereas those of cis-p-methoxyphenol-d(1)-OCH(2)D are 33 669 and 62 323 cm(-1), respectively. Similarly, the E(1) and IE of trans-p-methoxyphenol-d(1)-OD are determined to be 33 563 and 62 191 cm(-1) and those of trans-p-methoxyphenol-d(1)-OCH(2)D are 33 575 and 62 216 cm(-1), respectively. Comparing these data with those of p-methoxyphenol suggests that the H/D exchange on the OH substituent gives rise to a red shift in both the E(1) and IE, whereas that on the OCH(3) group yields a blue shift. The mass-analyzed threshold ionization spectra of the selected isomers can be used as the fingerprints for molecular identification. Analysis of these cation spectra shows that the substituent-sensitive in-plane C-OH and C-OCH(3) bending (mode 9b) and breathing (mode 1) vibrations are active for all of these isomeric cations.

Journal Article↗

PubMed2005

Dynamics of ultrathin films in the glassy state.

We report hole growth experiments in free-standing polystyrene (PS) films at temperatures up to 10 degrees C below the bulk glass transition. The data show an unexpected result: the growth rate of nucleated holes increases with increasing molecular weight, up to a limiting value beyond which the rate is approximately constant. Film thicknesses of 45, 80, and 100 nm were studied, using PS molecular weights ranging from 65K to 11.4 Mg/mol. Hole diameters grew linearly with time, and no growing rims were observed to form around the developing holes. Possible explanations in terms of elasticity, yield, and influence of sample preparation and confinement effects are discussed.

Journal Article↗

PubMed2005

Uniformly carbon-covered alumina and its surface characteristics.

Uniformly carbon-covered alumina (CCA) was prepared via the carbonization of sucrose highly dispersed on the alumina surface. The CCA samples were characterized by XRD, XPS, DTA-TG, UV Raman, nitrogen adsorption experiments at 77 K, and rhodamine B (RB) adsorption in aqueous media. UV Raman spectra indicated that the carbon species formed were probably conjugated olefinic or polycyclic aromatic hydrocarbons, which can be considered molecular subunits of a graphitic plane. The N(2) adsorption isotherms, pore size distributions, and XPS results indicated that carbon was uniformly dispersed on the alumina surface in the as-prepared CCA. The carbon coverage and number of carbon layers in CCA could be controlled by the tuning of the sucrose content in the precursor and impregnation times. RB adsorption isotherms suggested that the monolayer adsorption capacity of RB on alumina increased drastically for the sample with uniformly dispersed carbon. The as-prepared CCA possessed the texture of alumina and the surface properties of carbon or both carbon and alumina depending on the carbon coverage.

Journal Article↗

PubMed2005

A study of the preparation and reactivity of potassium ferrate.

In the context of water treatment, the ferrate ([FeO(4)](2-)) ion has long been known for its strong oxidizing power and for producing a coagulant from its reduced form (i.e. Fe(III)). However, it has not been studied extensively owing to difficulties with its preparation and its instability in water. This paper describes an improved procedure for preparing solid phase potassium ferrate of high purity (99%) and with a high yield (50-70%). The characteristics of solid potassium ferrate were investigated and from XRD spectra it was found that samples of the solid have a tetrahedral structure with a space group of D(2h) (Pnma) and a=7.705A, b=5.863A, and c=10.36A. The aqueous stability of potassium ferrate at various pH values and different concentrations was investigated. It was found that potassium ferrate solution had a maximum stability at pH 9-10 and that ferrate solution at low concentration (0.25 mM) was more stable than at high concentration (0.51 mM). The aqueous reaction of ferrate with bisphenol A (BPA), a known endocrine disrupter compound, was also investigated with a molar ratio of Fe(VI):BPA in the range of 1:1-5:1. The optimal pH for BPA degradation was 9.4, and at this pH and a Fe(VI):BPA molar ratio of 5:1, approximately 90% of the BPA was degraded after 60s.

Benzhydryl Compounds↗

PubMed2005

PRINTO/PRES international website for families of children with rheumatic diseases: www.pediatric-rheumatology.printo.it.

OBJECTIVE: To prepare a website for families and health professionals containing up to date information about paediatric rheumatic diseases (PRD). METHODS: Firstly, paediatric rheumatology centres and family self help associations were surveyed to characterise current clinical practice of physicians providing care for children with PRD, research activities, and training facilities of each centre. Secondly, international consensus was reached on the content of the website. Finally, the website was developed and the texts translated. RESULTS: The web page contains three main sections: (a) description for families of the characteristics of 15 PRD; (b) list of paediatric rheumatology centres; (c) contact information for family self help associations. A version for 45 countries in 52 languages (with another three in progress) is now available on the web. 291 surveys from 171 centres and 102 family associations were received from 42 countries. The median proportion of time spent in paediatric practice in the centres examined was 100%, with 70% of this time dedicated to paediatric rheumatology. 90% of the centres were willing to perform clinical trials in the future. CONCLUSIONS: The PRINTO/PRES website provides a well defined and competent set of information about PRD, with appropriate multiple translated versions and easy web navigational direction.

Child↗

PubMed2005

Lipofuscin accumulation, abnormal electrophysiology, and photoreceptor degeneration in mutant ELOVL4 transgenic mice: a model for macular degeneration.

Macular degeneration is a heterogeneous group of disorders characterized by photoreceptor degeneration and atrophy of the retinal pigment epithelium (RPE) in the central retina. An autosomal dominant form of Stargardt macular degeneration (STGD) is caused by mutations in ELOVL4, which is predicted to encode an enzyme involved in the elongation of long-chain fatty acids. We generated transgenic mice expressing a mutant form of human ELOVL4 that causes STGD. In these mice, we show that accumulation by the RPE of undigested phagosomes and lipofuscin, including the fluorophore, 2-[2,6-dimethyl-8-(2,6,6-trimethyl-1-cyclohexen-1-yl)-1E,3E,5E,7E-octatetraenyl]-1-(2-hyydroxyethyl)-4-[4-methyl-6-(2,6,6,-trimethyl-1-cyclohexen-1-yl)-1E,3E,5E-hexatrienyl]-pyridinium (A2E) is followed by RPE atrophy. Subsequently, photoreceptor degeneration occurs in the central retina in a pattern closely resembling that of human STGD and age-related macular degeneration. The ELOVL4 transgenic mice thus provide a good model for both STGD and dry age-related macular degeneration, and represent a valuable tool for studies on therapeutic intervention in these forms of blindness.

Animals↗

PubMed2005

Microvessel density and expression of vascular endothelial growth factor, basic fibroblast growth factor, and platelet-derived endothelial growth factor in oral squamous cell carcinomas.

Angiogenesis, the growth of capillary vessels, plays an important role in the metabolic functions of malignant tissues. Tumor growth and malignant transformation are considered to be dominated by uncontrolled angiogenesis. To understand the mechanism of increased vascularity associated with malignant tissues, we immunohistochemically evaluated microvessel density (MVD) and the expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and platelet-derived endothelial growth factor (PDGF) in oral cancers. Microvessel density did not differ significantly between normal oral mucosa and epithelial dysplasia, but was significantly increased in tumor tissues. Expression of angiogenic factors was not found in normal oral mucosa, but increased in association with increasing vascularity in OSCC tissue. In tumor tissue, angiogenic factor expression correlated with MVD. MVD in OSCC was related to T stage, tumor differentiation, and stage of invasion. VEGF expression also correlated with tumor differentiation and the stage of invasion. These findings suggest that VEGF might play an important role in tumor angiogenesis of OSCC.

Adult↗

PubMed2005

H-Ras oncogene counteracts the growth-inhibitory effect of genistein in T24 bladder carcinoma cells.

Among eight human bladder cancer cell lines we examined, only T24 cells were resistant to the growth inhibition effect of genistein, an isoflavone and potent anticancer drug. Since the T24 cell line was the only cell line known to overexpress oncogenic H-Ras(val 12), we investigated the role of H-Ras(val 12) in mediating drug resistance. Herein, we demonstrate that the phenotype of T24 cells could be dramatically reversed and became relatively susceptible to growth inhibition by genistein if the synthesis of H-Ras(val 12) or its downstream effector c-Fos had been suppressed. The inhibition of Ras-mediated signalling with protein kinase inhibitors, such as PD58059 and U0126 which inhibited MEK and ERK, in T24 cells also rendered the identical phenotypic reversion. However, this reversion was not observed when an inhibitor was used to suppress the protein phosphorylation function of PI3 K or PKC. These results suggest that the signal mediated by H-Ras(val 12) is predominantly responsible for the resistance of the cells to the anticancer drug genistein.

Antineoplastic Agents↗

PubMed2005

Structural requirements for cannabinoid receptor probes.

The discovery and cloning of CB1 and CB2, the two known G(i/o) protein-coupled cannabinoid receptors, as well as the isolation and characterization of two families of endogenous cannabinergic ligands represented by arachidonoylethanolamide (anandamide) and 2-arachidonoylglycerol (2-AG), have opened new horizons in this newly discovered field of biology. Furthermore, a considerable number of cannabinoid analogs belonging to structurally diverse classes of compounds have been synthesized and tested, thus providing substantial information on the structural requirements for cannabinoid receptor recognition and activation. Experiments with site-directed mutated receptors and computer modeling studies have suggested that these diverse classes of ligands may interact with the receptors through different binding motifs. The information about the exact binding site may be obtained with the help of suitably designed molecular probes. These ligands either interact with the receptors in a reversible fashion (reversible probes) or alternatively attach at or near the receptor active site with the formation of covalent bonds (irreversible probes). This review focuses on structural requirements of cannabinoid receptor ligands and highlights their pharmacological and therapeutic potential.

Animals↗

PubMed2005

High iodine intake is a risk factor of post-partum thyroiditis: result of a survey from Shenyang, China.

The aim of the present study is to obtain the epidemiological data on post-partum thyroiditis (PPT) firstly in Chinese women, and to tryto evaluate whether excessive intake of iodine in post-partum women imposes any danger of occurring PPT. Sixty hundred and ten pregnant women were involved in the cohort just before delivery. Four hundred and eighty-eight (80%) of them accepted taking part in follow-ups more than 6 months post-partum. A blood sample was taken from participants before delivery and every 3 months post-partum for testing of serum TSH, thyroid autoantibodies. Free T3 (FT3), free T4 (FT4) and TSH receptor antibody (TRAb) were detected if TSH was abnormal. The iodine nutrition was evaluated according to the mean level of the fasting urinary iodine excretions at different times during the studying period, and participants were subgrouped into 3 categories with low, adequate and high iodine intake. For those participants who had thyroid dysfunction within 6 months post-partum, the follow-up persisted for 1 yr. Of 488 pregnant women, PPT developed in 11.9% (58/488). Given overt and subclinical PPT, the prevalence was 7.17% (no.=35) and 4.71% (no.=23), respectively. There was a strong association between the presence of thyroid peroxidase antibody (TPOAb) at delivery and the risk of developing PPT [RR=6.76, 95% (CI) 4.42-10.34]. Overt cases had much higher titers of TPOAb than subclinical patients (all p<0.05). The median urinary iodine (MUI) of patients with PPT was significantly higher than that of healthy women (231.93 vs 199.88 microg/l p=0.00153). Both the prevalence of PPT and positive TPOAb rise with the increment of iodine intakes. Pregnant women with high iodine intake had more risk of developing PPT when compared with those with low iodine intake (RR=2.92, 95%CI 1.31-6.50). We concluded that positive TPOAb was of value for predicting the occurrence and severity of PPT, and a high iodine intake was a risk factor triggering PPT.

Adult↗

PubMed2005

Antileukemic effect of interleukin-7-transduced bone marrow stromal cells in mice following allogeneic T-cell-depleted bone marrow transplantation.

Impaired immune reconstitution following allogeneic bone marrow transplantation (BMT) remains a major obstacle to its clinical application. In this study, interleukin (IL)-7-transduced bone marrow stromal cells (MSC-IL7, 1 x 10(6)/mouse) were transfused into lethally irradiated C57BL/6 recipient mice. By day 40 after transplantation, the recipient mice were challenged with the lymphoma cell line EL4. MSC-IL7 co-transplantation protected recipient mice from leukemic mortality (MST >120 days after BMT vs mean survival time (MST) 70 days in the PBS group) It enhance the PFC count and DTH responses of recipients after transplantation. In conclusion, MSC mediated IL-7 gene therapy and may be a more feasible strategy to restore immune function following allo-TCD-BMT.

Animals↗

PubMed2005

The ever-expanding neuropeptide gene families in the nematode Caenorhabditis elegans.

Neuropeptides act as chemical signals in the nervous system to modulate behaviour. With the ongoing EST projects and DNA sequence determination of different genomes, the identification of neuropeptide genes has been made easier. Despite the relatively 'simple' repertoire of behaviours in the nematode Caenorhabditis elegans, this worm contains a surprisingly large and diverse set of neuropeptide genes. At least 109 genes encoding over 250 potential neuropeptides have been identified in C. elegans; all genes are likely to be expressed and many, if not all, of the predicted peptides are produced. The predicted peptides include: 38 insulin-like peptides, several of which are involved in development and reproductive growth, and over 70 FMRFamide-related peptides, some of which are involved in locomotion, reproduction, and social behaviour. Many of the C. elegans peptides are identical or highly similar to those isolated or predicted in parasitic nematodes, such as Ascaris suum, Haemonchus contortus, Ancylostoma caninum, Heterodera glycines and Meloidogyne arenaria, suggesting that the function of these peptides is similar across species. The challenge for the future is to determine the function of all the genes and individual peptides and to identify the receptors through which the peptides signal.

Animals↗

PubMed2005

VEGF165 and angiopoietin-1 decreased myocardium infarct size through phosphatidylinositol-3 kinase and Bcl-2 pathways.

Angiogenic growth factors, vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang1) could decrease myocardial infarct size, which was assumed to be related with newly formed capillaries. We doubted that these capillaries could do this solely and the potential protective mechanisms of VEGF and Ang1 on myocardium need to be evaluated. Three types of adenoviruses encoding human VEGF(165) (Ad-VEGF(165)), human angiopoietin-1 (Ad-Ang1) and green fluorescent protein (Ad-GFP, as a parallel control) were constructed. Experiments were taken both in vitro and in vivo. As in vitro, the antiapoptosis effect of VEGF(165), Ang1 and VEGF(165)+Ang1 on cardiac myoblasts was observed, which seemed to be related with the activation of phosphatidylinositol-3 kinase and Bcl-2 pathways. As in vivo, adenoviruses were intramyocardially injected immediately after the ligation of the left anterior descending coronay arteries in rats. The results showed positive effect of VEGF(165), Ang1 and VEGF(165)+Ang1 on decreasing the myocardial infarct size at the 7th day. Myocardial PI-3K activity and Bcl-2 expression were elevated relatively at the 3rd day. The protective effect of VEGF(165) and Ang1 on the myocardium may broaden their functional research and contribute to their clinical use in the future.

Adenoviridae↗

PubMed2005

Glucokinase and glucose homeostasis: proven concepts and new ideas.

The enzyme GK (glucokinase), which phosphorylates glucose to form glucose 6-phosphate, serves as the glucose sensor of insulin-producing beta-cells. GK has thermodynamic, kinetic, regulatory and molecular genetic characteristics that are ideal for its glucose sensor function and allow it to control glycolytic flux of the beta-cells as indicated by control-, elasticity- and response-coefficients close to or larger than 1.0. GK operates in tandem with the K(+) and Ca(2+) channels of the beta-cell membrane, resulting in a threshold for glucose-stimulated insulin release of approx. 5 mM, which is the set point of glucose homoeostasis for most laboratory animals and humans. Point mutations of GK cause 'glucokinase disease' in humans, which includes hypo- and hyper-glycaemia syndromes resulting from activating or inactivating mutations respectively. GK is allosterically activated by pharmacological agents (called GK activators), which lower blood glucose in normal animals and animal models of T2DM. On the basis of crystallographic studies that identified a ligand-free 'super-open' and a liganded closed structure of GK, on thermostability studies using glucose or mannoheptulose as ligands and studies showing that mannoheptulose alone or combined with GK activators induces expression of GK in pancreatic islets and partially preserves insulin secretory competency, a new hypothesis was developed that GK may function as a metabolic switch per se without involvement of enhanced glucose metabolism. Current research has the goal to find molecular targets of this putative 'GK-switch'. The case of GK research illustrates how basic science may culminate in therapeutic advances of human medicine.

Crystallography, X-Ray↗

PubMed2005

Induction of oral tolerance in experimental Sjogren's syndrome autoimmunity.

Previous studies have showed that immunization with peptides from Ro 60 results in Sjogren's syndrome (SS)-like condition in BALB/c mice. We hypothesized that oral feeding with Ro 60 peptide or Ro 60 would prevent the disease. Four groups (each consisting of 10) of BALB/c mice were used. Group I-III were immunized with Ro 274 peptide. Group IV mice were administered adjuvant only. Group II mice were fed orally with Ro 274 peptide and Group III with Ro 60 for 5 days before immunization. There was a significant reduction in the binding of sera from both Group II and Group III mice to most of the Ro multiple antigenic peptides bound by Group I mice. In Group III mice, salivary flow was maintained above that of the Group I mice (average: 117.5 versus 58.6 microl; t = 2.7; P = 0.02). Salivary infiltrates were drastically decreased in the Ro peptide or Ro 60-fed groups, compared to non-tolerized group. Two of eight mice in Group II and 3/6 mice in Group III had no infiltrates, whereas all eight mice studied in Group I had a significant number of infiltrates. Thus, epitope spreading was prevented, lymphocytic infiltration was blocked and saliva flow was restored by means of oral feeding of either Ro 274 or Ro 60 in this animal model of SS.

Administration, Oral↗

PubMed2005

Distribution of human chemokine (C-X3-C) receptor 1 (CX3CR1) gene polymorphisms and haplotypes of the CC chemokine receptor 5 (CCR5) promoter in Chinese people, and the effects of CCR5 haplotypes on CCR5 expression.

Two chemokine (C-X3-C) receptor 1 (CX3CR1) gene polymorphisms, V249I and T280M, and 10 CC chemokine receptor 5 (CCR5) promoter haplotypes, P1-P10, have recently been reported to influence the progression of acquired immune-deficiency syndrome (AIDS). As these studies were performed mainly with Caucasian and African-American subjects, we determined the distribution of these alleles in Chinese people for the purpose of predicting possible clinical responses to the human immunodeficiency virus type 1 (HIV) epidemics in countries with significant Chinese populations, as well as to establish their effects on the expression of surface CCR5. Ninety-six HIV-negative Chinese individuals in Taiwan were subjected to genotyping, and we thus determined that the allelic frequencies of CX3CR1V249I and T280M changes were 2.6% and 2.1%, respectively, which were lower than found in Caucasians (25.5% and 14.0%, respectively). Unlike the previous reports, we only detected CCR5P1 and P4 haplotypes in Taiwanese people, and the P1/P1, P1/P4 and P4/P4 genotype frequencies were 21.0%, 41.1% and 37.9%, respectively. The sequencing data confirmed the results of previous studies, showing that CCR5P1 exhibited a complete linkage disequilibrium with a polymorphic allele 59029A present in the CCR5 promoter. Furthermore, fluorescence-activated cell sorter analysis revealed that, in the absence of the CCR2-64I mutation, individuals carrying CCR5P1 tended to express more surface CCR5 on monocytes and CD4+ cells. Therefore, this study not only reports the frequencies for the CX3CR1 and CCR5 promoter haplotypes in a Chinese population living in Taiwan, but also identifies a statistical link between the P1/P1 haplotype and the elevated CCR5 expression levels in the study group.

Adult↗

PubMed2005

Polymorphisms in the bovine leptin promoter associated with serum leptin concentration, growth, feed intake, feeding behavior, and measures of carcass merit.

Leptin is the hormone product of the obese gene synthesized and secreted predominantly by white adipocytes. It functions as a lipostatic signal regulating BW, food intake, energy expenditure, reproduction, and certain immune system functions. Although previous studies have identified polymorphisms in the coding regions of the leptin gene in cattle that show considerable associations with feed intake, milk quality and quantity, and carcass fatness, no such associations have been reported for the leptin promoter. The current study reports associations between SNP in the 5' untranslated promoter region of the bovine leptin gene with serum leptin concentration, growth, BW, feed intake, feeding behavior, and carcass merit in hybrid cattle (n = 150). The study showed that animals with the TT genotype of a less frequent cytosine/thymine (C/ T) substitution (UASMS2; frequency of thymine allele equals 0.21) detected at position 528 in the bovine leptin promoter (GenBank Accession No. AB070368) show 48 and 39% increases in serum leptin concentration (P < 0.001), 39 and 31% increases in backfat thickness (P < 0.001), and 13 and 9% increase in marbling score (P = 0.01), compared with CC or CT genotypes, respectively. Animals with the TT genotype also show significantly higher feed intake (P < 0.001), growth rate, metabolic BW (P < 0.05), and live weight at slaughter (P < 0.10). Animals with the GG genotype of a more frequent cytosine/guanine (C/G) substitution (UASMS3; frequency of G allele equals 0.59) at position 1759 in the bovine leptin promoter (GenBank Accession No. AB070368) also show higher feed intake (P = 0.001), growth rate (P < 0.10), and BW (P < 0.01). The thymine allele of UASMS2 and the guanine allele of UASMS3 were separately associated with higher feeding duration (P < 0.05). The two SNP show significant linkage disequilibrium and could also be relevant in predicting other characteristics, such as milk yield and quality in cattle. These results, however, represent the initial associations of the polymorphisms with these traits, and further efforts are required to validate these findings in other populations.

Animals↗