Showing papers by "Sun Yat-sen University published in 2004"

Syntheses, structures, photoluminescence, and theoretical studies of d(10) metal complexes of 2,2'-dihydroxy-[1,1']binaphthalenyl-3,3'-dicarboxylate.

Abstract: The free solvated ligand, H(2)bna.CH(3)OH.H(2)O (1), and its dimeric complex, [Cd(2)(bna)(2)(H(2)O)(6)] (2) (bna = 2,2'-dihydroxy-[1,1']-binaphthalene-3,3'-dicarboxylate), were obtained by evaporation of the solutions, while two new d(10) metal-hydroxy cluster-based coordination polymers, namely [Cd(8)(OH)(4)(H(2)O)(10)(bna)(6)].17H(2)O (3) and [Hpy](2)[Zn(4)(OH)(2)(H(2)O)(2)(bna)(4)].2H(2)O.2CH(3)CN (4), were obtained by a hydrothermal route. All the compounds have been characterized by X-ray crystallography and photoluminescence measurements. Compound 1 consists of a three-dimensional, hydrogen-bonded supramolecular array, 2 exhibits a dimeric molecule featuring a square motif organized by two Cd(II) atoms and two bna ligands each at the corner, and 3 contains unprecedented [Cd(8)(micro(3)-OH)(2)(micro-OH)(2)(micro-H(2)O)(2)](12+) octanuclear metallacrown cores which are interlinked through bna to afford a two-dimensional structure, while 4 features layers with butterfly-shaped [Zn(4)(micro(3)-OH)(2)](6+) clusters. All the complexes display photoluminescent properties in the blue/green range. The manifestation of photoluminescence, as probed by molecular orbital calculations performed on the complexes and also on hypothetical multinuclear complexes, is attributed to a ligand-to-metal charge-transfer mechanism. In addition to presenting a new approach for the study of the photoluminescent properties of metal-cluster-based coordination polymers by using simple model compounds, the study also reveals the dominant role of the structure of the ligand over that of the d(10) metal-hydroxy (or oxy) cluster and the presence of the cluster significantly increasing the emission lifetime.

Molecular Evolution of the SARS Coronavirus, during the Course of the SARS Epidemic in China

Abstract: Sixty-one SARS coronavirus genomic sequences derived from the early, middle, and late phases of the severe acute respiratory syndrome (SARS) epidemic were analyzed together with two viral sequences from palm civets. Genotypes characteristic of each phase were discovered, and the earliest genotypes were similar to the animal SARS-like coronaviruses. Major deletions were observed in the Orf8 region of the genome, both at the start and the end of the epidemic. The neutral mutation rate of the viral genome was constant but the amino acid substitution rate of the coding sequences slowed during the course of the epidemic. The spike protein showed the strongest initial responses to positive selection pressures, followed by subsequent purifying selection and eventual stabilization.

Recent Advances in Luminescent Monomeric, Multinuclear, and Polymeric Zn(II) and Cd(II) Coordination Complexes

Abstract: ‘Luminescence research has a long history full of splendor and surprise, and a bright future, promising variegated applications to probe molecules and crystals, to visualize atomic phenomena, ...’ H. J. Queisser, 1981 This article briefly summarizes recent progress on the luminescence studies of monomeric, multinuclear, and polymeric Zn(ii)/Cd(ii) coordination complexes, involving spectroscopic, photophysical, and photochemical studies, as well as molecular and electronic structural investigations, focussing mainly on the interplaying factors that govern the luminescent origin of the lowest-lying emissive states. Current results show that, for Zn(ii)/Cd(ii) coordination complexes in general, the nature of the metal centres and ligands and the rigid metal-oxy (or -hydroxy) clusters are factors governing their luminescent origin of the lowest-lying emissive states; different types of ligands and coordination structures may result in different emission mechanisms.

Spotted leaf11 , a Negative Regulator of Plant Cell Death and Defense, Encodes a U-Box/Armadillo Repeat Protein Endowed with E3 Ubiquitin Ligase Activity

Abstract: The rice (Oryza sativa) spotted leaf11 (spl11) mutant was identified from an ethyl methanesulfonate–mutagenized indica cultivar IR68 population and was previously shown to display a spontaneous cell death phenotype and enhanced resistance to rice fungal and bacterial pathogens. Here, we have isolated Spl11 via a map-based cloning strategy. The isolation of the Spl11 gene was facilitated by the identification of three additional spl11 alleles from an IR64 mutant collection. The predicted SPL11 protein contains both a U-box domain and an armadillo (ARM) repeat domain, which were demonstrated in yeast and mammalian systems to be involved in ubiquitination and protein–protein interactions, respectively. Amino acid sequence comparison indicated that the similarity between SPL11 and other plant U-box-ARM proteins is mostly restricted to the U-box and ARM repeat regions. A single base substitution was detected in spl11, which results in a premature stop codon in the SPL11 protein. Expression analysis indicated that Spl11 is induced in both incompatible and compatible rice–blast interactions. In vitro ubiquitination assay indicated that the SPL11 protein possesses E3 ubiquitin ligase activity that is dependent on an intact U-box domain, suggesting a role of the ubiquitination system in the control of plant cell death and defense.

Induction of long-term glycemic control in newly diagnosed type 2 diabetic patients is associated with improvement of beta-cell function.

Abstract: OBJECTIVE —To investigate whether long-term optimal glycemic control can be achieved without medication by transient continuous subcutaneous insulin infusion (CSII) and the possible mechanisms responsible for this remission. RESEARCH DESIGN AND METHODS —Newly diagnosed type 2 diabetic patients ( n = 138, fasting glucose >11.1mmol/l) were hospitalized and treated with CSII for 2 weeks. Intravenous glucose tolerance tests (IVGTTs) were performed, and blood glucose, HbA 1c , lipid profiles, proinsulin, insulin, and C-peptide were measured before and after CSII. Patients were followed longitudinally on diet alone after withdrawal of insulin. RESULTS —Optimal glycemic control was achieved within 6.3 ± 3.9 days by CSII in 126 patients. The remission rates (percentages maintaining near euglycemia) at the third, sixth, twelfth, and twenty-fourth month were 72.6, 67.0, 47.1, and 42.3%, respectively. Patients who maintained glycemic control >12 months (remission group) had greater recovery of β-cell function than those who did not (nonremission group) when assessed immediately after CSII. Homeostasis model assessment of β-cell function (HOMA-B) and the area under the curve (AUC) of insulin during IVGTT were higher in the remission group (145.4 ± 89.6 vs. 78.5 ± 68.5, P = 0.002, and 1,423.4 ± 523.2 vs. 1,159.5 ± 476.8 pmol · l −1 · min −1 , P = 0.044). Change in acute insulin response was also greater in the remission group than that in the nonremission group (621.8 ± 430.4 vs. 387.3 ± 428.8 pmol · l −1 · min −1 , P = 0.033). CONCLUSIONS —Short-term intensive insulin therapy can induce long-term glycemic control in newly diagnosed type 2 diabetic patients with severe hyperglycemia. The improvement of β-cell function, especially the restoration of first-phase insulin secretion, could be responsible for the remission.

A New Route to Supramolecular Isomers via Molecular Templating: Nanosized Molecular Polygons of Copper(I) 2-Methylimidazolates

Abstract: A new facile synthetic strategy successfully leads to the isolation of two polygons of high numbers of sides constructed by simple, bent imidazolate bridging ligands and two-coordinate CuI ions upon templating of circular organic molecules, which were characterized by crystallography.

Comparative investigation on synthesis and photoluminescence of YAG:Ce phosphor

Abstract: Phosphor yttrium aluminum garnet Y3Al5O12 (YAG), activated with trivalent cerium (Ce3+) was synthesized by different methods: solid-state reaction (SS), co-precipitation (CP) with ammonium bicarbonate, sol–gel (SG) with citric acid and combustion (CB) with urea. The crystallization, morphologies, particle size and luminescent character of the phosphors obtained under different experimental conditions were studied. The influences of various factors on the luminescence intensity of the phosphor were investigated, such as sintering time, repeated calcinations, reaction temperature, and quantities of urea used in CB.

Bietti crystalline corneoretinal dystrophy is caused by mutations in the novel gene CYP4V2.

Abstract: Bietti crystalline corneoretinal dystrophy (BCD) is an autosomal recessive retinal dystrophy characterized by multiple glistening intraretinal crystals scattered over the fundus, a characteristic degeneration of the retina, and sclerosis of the choroidal vessels, ultimately resulting in progressive night blindness and constriction of the visual field. The BCD region of chromosome 4q35.1 was refined to an interval flanked centromerically by D4S2924 by linkage and haplotype analysis; mutations were found in the novel CYP450 family member CYP4V2 in 23 of 25 unrelated patients with BCD tested. The CYP4V2 gene, transcribed from 11 exons spanning 19 kb, is expressed widely. Homology to other CYP450 proteins suggests that CYP4V2 may have a role in fatty acid and steroid metabolism, consistent with biochemical studies of patients with BCD.

Team Learning from Mistakes: The Contribution of Cooperative Goals and Problem-Solving

Abstract: Although mistakes may have considerable potential for learning, previous research has emphasized that organizational members are often defensive when their mistakes are pointed out and will even continue with their present course of action despite growing costs. Recent research has shown that team-level variables, such as psychological safety and shared mental model, can help overcome barriers to learning from mistakes. Structural equation analyses on teams working in a sample of organizations in Shanghai, China, suggested that teams were able to learn from their mistakes to the extent that they took a problem solving orientation. This orientation in turn was based on developing cooperative but not competitive goals within the team. Although competitive and independent goals induce blaming, blaming itself was not significantly related to learning. Blaming, especially when conducted openly, may hold individual team members accountable as well as provoke defensiveness. Findings empirically link the theory of cooperation and competition with the organizational learning literature. Results suggest that cooperative goals and problem solving promote learning from mistakes.

Catch bonds govern adhesion through L-selectin at threshold shear.

Abstract: Flow-enhanced cell adhesion is an unexplained phenomenon that might result from a transport-dependent increase in on-rates or a force-dependent decrease in off-rates of adhesive bonds. L-selectin requires a threshold shear to support leukocyte rolling on P-selectin glycoprotein ligand-1 (PSGL-1) and other vascular ligands. Low forces decrease L-selectin–PSGL-1 off-rates (catch bonds), whereas higher forces increase off-rates (slip bonds). We determined that a force-dependent decrease in off-rates dictated flow-enhanced rolling of L-selectin–bearing microspheres or neutrophils on PSGL-1. Catch bonds enabled increasing force to convert short-lived tethers into longer-lived tethers, which decreased rolling velocities and increased the regularity of rolling steps as shear rose from the threshold to an optimal value. As shear increased above the optimum, transitions to slip bonds shortened tether lifetimes, which increased rolling velocities and decreased rolling regularity. Thus, force-dependent alterations of bond lifetimes govern L-selectin–dependent cell adhesion below and above the shear optimum. These findings establish the first biological function for catch bonds as a mechanism for flow-enhanced cell adhesion.

Pharmacokinetic interactions of drugs with St John's wort

Abstract: There is a worldwide increasing use of herbs which are often administered in combination with therapeutic drugs, raising the potential for herb-drug interactions. St John's wort (Hypericum perforatum) is one of the most commonly used herbal antidepressants. A literature search was performed using Medline (via Pubmed), Biological Abstracts, Cochrane Library, AMED, PsycINFO and Embase (all from their inception to September 2003) to identify known drug interaction with St John's wort. The available data indicate that St John's wort is a potent inducer of CYP 3A4 and P-glycoprotein (PgP), although it may inhibit or induce other CYPs, depending on the dose, route and duration of administration. Data from human studies and case reports indicate that St John's wort decreased the blood concentrations of amitriptyline, cyclosporine, digoxin, fexofenadine, indinavir, methadone, midazolam, nevirapine, phenprocoumon, simvastatin, tacrolimus, theophylline and warfarin, whereas it did not alter the pharmacokinetics of carbamazepine, dextromethorphan, mycophenolic acid and pravastatin. St John's wort decreased the plasma concentration of the active metabolite SN-38 in cancer patients receiving irinotecan treatment. St John's wort did not alter the pharmacokinetics of tolbutamide, but increased the incidence of hypoglycaemia. Several cases have been reported that St John's wort decreased cyclosporine blood concentration leading to organ rejection. St John's wort caused breakthrough bleeding and unplanned pregnancies when used concomitantly with oral contraceptives. It also caused serotonin syndrome when coadministered with selective serotonin-reuptake inhibitors (e.g. sertaline and paroxetine). Both pharmacokinetic and pharmacodynamic components may play a role in these interactions. Because the potential interaction of St John's wort with other drugs is a major safety concern, additional systematic research on herb-drug interactions and appropriate regulation in herbal safety and efficacy is needed.

CD3/CD28 Costimulation-Induced NF-κB Activation Is Mediated by Recruitment of Protein Kinase C-θ, Bcl10, and IκB Kinase β to the Immunological Synapse through CARMA1

Abstract: CARMA1 (also known as CARD11) is a scaffold molecule and contains a caspase-recruitment domain (CARD) and a membrane-associated guanylate kinase-like (MAGUK) domain. It plays an essential role in mediating CD3/CD28 costimulation-induced NF-kappaB activation. However, the molecular mechanism by which CARMA1 mediates costimulatory signals remains to be determined. Here, we show that CARMA1 is constitutively associated with the cytoplasmic membrane. This membrane association is essential for the function of CARMA1, since a mutant of CARMA1, CARMA1(L808P), that is defective in the membrane association cannot rescue CD3/CD28 costimulation-induced NF-kappaB activation in JPM50.6 CARMA1-deficient T cells. Although CD3/CD28 costimulation effectively induces the formation of the immunological synapse in CARMA1-deficient T cells, the recruitment of protein kinase C-theta (PKC-theta), Bcl10, and IkappaB kinase beta (IKKbeta) into lipid rafts of the immunological synapse is defective. Moreover, expression of wild-type CARMA1, but not CARMA1(L808P), restores the recruitment of PKC-theta, Bcl10, and IKKbeta into lipid rafts in CARMA1-deficient T cells. Consistently, expression of a mutant CARMA1, CARMA1(DeltaCD), that cannot associate with Bcl10 failed to restore CD3/CD28 costimulation-induced NF-kappaB activation in JPM50.6 cells, whereas expression of Bcl10-CARMA(DeltaCD) fusion protein effectively restored this NF-kappaB activation. Together, these results indicate that CARMA1 mediates CD3/CD28 costimulation-induced NF-kappaB activation by recruiting downstream signaling components into the immunological synapse.

[Phase III randomized clinical trial of intratumoral injection of E1B gene-deleted adenovirus (H101) combined with cisplatin-based chemotherapy in treating squamous cell cancer of head and neck or esophagus].

Abstract: Background & objective H101 is an E1B-55 kDa gene-deleted replication-selective adenovirus, which showed a significant antitumor activity. This study was to compare effects and toxicities of intratumoral H101 injection combined with cisplatin plus 5-fluorouracil (PF) regimen or adriamycin plus 5-fluorouracil (AF) regimen versus PF or AF regimen alone in treating patients with head and neck or esophagus squamous cell cancer. Methods A total of 160 patients were recruited. PF regimen (cisplatin 20 mg/m(2) ivgtt, qd x 5d; 5-fluorouracil 500 mg/m(2) ivgtt, qd x 5d) was administered to patients have no history of PF chemotherapy,or sensitive to PF chemotherapy,while AF regimen (adriamycin 50 mg/m(2) iv,d1; 5-fluorouracil 500 mg/m(2) ivgtt, qd x 5d) was administered to patients didn't response to PF regimen. All patients were randomized to either receive intratumoral H101 injection (5.0 x 10(11)-1.5 x 10(12) VP/day for 5 consecutive days every 3 weeks) or not. Treatment repeated every 3 weeks,all patients have to receive at least 2 cycles of chemotherapy. Results Among 123 accordant patients,overall response rate of PF plus H101 group (group A1) was 78.8% (41/52),of PF alone group (group B1) was 39.6% (21/53),of AF plus H101 group (group A2) was 50.0% (7/14),of AF alone group (group B2) was 50.0% (2/4). Differences of response rates between group A1 and group B1,between group A1+A2 and group B1+B2 were significant (P=0.000). Main side effects were fever (45.7%), injection site reaction (28.3%),and influenza-like symptoms (9.8%). Conclusion Intratumoral H101 injection showed a distinct efficacy in patients with squamous cell cancer of head and neck or esophagus,and was relatively safe.

Association of Vimentin overexpression and hepatocellular carcinoma metastasis

Abstract: The poor prognosis of hepatocellular carcinoma (HCC) has been associated with recurrence and metastasis. Recently, we established a pair of HCC cell lines from a primary (H2-P) and its matched metastatic (H2-M) HCC tumors. A high density of cDNA microarray with 9184 human cDNA was used to identify the differentially expressed genes between H2-P and H2-M. Comparing with H2-P, eight upregulated and six downregulated genes were detected in H2-M. One interesting finding is the overexpression of Vimentin (VIM), a well-defined intermediate filament, which has been linked to a more aggressive status in various tumors. The correlation of overexpression of VIM and HCC metastasis was studied by immunohistochemistry using a tissue microarray with 200 primary HCCs and 60 pairs of primary and matched metastatic HCC samples. Tissue microarray demonstrated that the overexpression of VIM was significantly associated with HCC metastasis (P<0.01). This finding strongly suggests that the overexpression of VIM may play an important role in the metastasis of HCC.

Comparison of plasma Epstein-Barr virus (EBV) DNA levels and serum EBV immunoglobulin A/virus capsid antigen antibody titers in patients with nasopharyngeal carcinoma.

Abstract: BACKGROUND Serologic measurement of antibodies to Epstein–Barr virus (EBV) immunoglobulin A/viral capsid antigen (IgA/VCA) and early antigen (IgA/EA) has been used widely to screen for nasopharyngeal carcinoma (NPC) in China. Recently, it was found that plasma EBV DNA concentration is an indicator for the staging and prognosis of patients with NPC. To determine whether there is a correlation between plasma EBV DNA levels and serum levels of IgA/VCA, the authors measured both in patients with NPC and in a control group. METHODS Real-time polymerase chain reaction was used for quantitative analysis of plasma EBV DNA concentration, and enzyme-linked immunoadsorbent assay was used to measure EBV VCA/IgA in patients with primary NPC (n = 120 patients), locally recurrent NPC (n = 8 patients), and distant metastatic NPC (n = 21 patients) among 76 patients with NPC after the completion of radiotherapy, in 60 patients with NPC in clinical remission, in 38 patients with non-NPC tumors, and in 47 control individuals. RESULTS The median plasma EBV DNA levels were 6200 copies/mL, 9200 copies/mL, and 2050 copies/mL in patients with primary, locally recurrent, and distant metastatic NPC, respectively, but declined to 0 copies/mL in patients with clinically remissive NPC, in patients who completed radiotherapy, in patients with non-NPC tumors, and in the control group. In contrast, EBV VCA/IgA titers and detection rates remained high in all NPC groups. Plasma EBV DNA levels were significantly higher in patients who had serum VCA/IgA titers ≥ 1:640 (median, 83,450 copies/mL) compared with the levels in patients who had titers ≤ 1:320 (median, 17,200 copies/mL). Patients with NPC who had advanced TNM stage (Stages III and IV; median, 8530 copies/mL) and T classification (T3 and T4 tumors; median, 8530 copies/mL) had significantly higher plasma EBV DNA levels compared with patients who had early TNM stage (Stages I and II; median, 930 copies/mL) and T classification (T1 and T2 tumors; median, 3700 copies). Patients who had advanced TNM stage NPC had significantly higher mean VCA/IgA titers (1:424) compared with patients who had early TNM stage NPC (1:246), but there was no correlation between IgA/VCA titer and T or N classification of NPC. CONCLUSIONS The results suggest that plasma EBV DNA detection is a more sensitive and specific marker than the serum IgA/VCA titer for the diagnosis and monitoring of patients with NPC. These findings provide convincing evidence for the use of plasma EBV DNA measurements for the early diagnosis and staging of NPC as well as for monitoring recurrence and metastasis of this tumor. Cancer 2004. © 2004 American Cancer Society.

Data mining of cellular automata's transition rules

Abstract: This paper presents a new method to discover knowledge for geographical cellular automata (CA) by using a data-mining technique. CA have the ability to simulate complex geographical phenomena. Very few studies have been carried out on how to determine and validate the transition rules of CA from observed data. The transition rules of traditional CA are usually expressed by mathematical equations. This paper demonstrates that the explicit transition rules of CA can be automatically reconstructed through the rule induction procedure of data mining. The explicit transition rules are more intuitive to decision-makers. The transition rules are obtained by applying data-mining techniques to spatial data. The proposed method can reduce the uncertainties in defining transition rules and help to generate more reliable simulation results.

Study on the communities of endophytic fungi and endophytic actinomycetes from rice and their antipathogenic activities in vitro

Abstract: The populations of endophytic fungi and actinomycetes from four rice cultivars in the Panyu district (Site 1) and Wushan district (Site 2) in Guangdong province, South China, were studied. The preponderant endophytic fungi and actinomycetes isolated belonged to Fusarium and Streptomyces respectively. The incidence of Streptomycetes griseofuscus ranged from 36.1 to 69% out of all the different rice cultivars from the two sites. It is the commonest population of endophytic actinomycetes, and constituted the greatest part of all the antagonistic communities. The distributions of endophytic fungi and actinomycetes in roots and leaves were different, endophytic fungi from leaves were diverse, some were organ-specific. More diverse endophytic actinomycetes were isolated from roots than from leaves. The endophytic fungi isolated from rice in Site 2 were more diverse than that in Site 1. The diversity of the endophytic actinomycetes, however, was less than that in Site 1. Acid soil in Site 2 is ideal for the growth and colonization of fungi while the alkaline soil in Site 1 is better for the growth and colonization of actinomycetes. The results suggested that differences in the chemical composition of soil could influence the endophytic microbial communities of rice plants. The endophytic fungi and actinomycetes isolated from poor-growing seedlings and susceptible rice cultivars were more abundant than that the disease-resistant counterparts. In the dual culture and activity detection of the metabolites, 41.2% of all the isolated endophytic fungi showed antagonism to rice pathogens. Fifty percent of all the isolated endophytic actinomycetes were antagonistic to those pathogens. The percentage of Streptomyces griseofuscus and hygroscopicus reached 55.4 and 21.4% of all the active actinomycetes.

PKHD1 protein encoded by the gene for autosomal recessive polycystic kidney disease associates with basal bodies and primary cilia in renal epithelial cells

Abstract: Mutations of the polycystic kidney and hepatic disease 1 (PKHD1) gene have been shown to cause autosomal recessive polycystic kidney disease (ARPKD), but the cellular functions of the gene product (PKHD1) remain uncharacterized. To illuminate its properties, the spatial and temporal expression patterns of PKHD1 were determined in mouse, rat, and human tissues by using polyclonal Abs and mAbs recognizing various specific regions of the gene product. During embryogenesis, PKHD1 is widely expressed in epithelial derivatives, including neural tubules, gut, pulmonary bronchi, and hepatic cells. In the kidneys of the pck rats, the rat model of which is genetically homologous to human ARPKD, the level of PKHD1 was significantly reduced but not completely absent. In cultured renal cells, the PKHD1 gene product colocalized with polycystin-2, the gene product of autosomal dominant polycystic disease type 2, at the basal bodies of primary cilia. Immunoreactive PKHD1 localized predominantly at the apical domain of polarized epithelial cells, suggesting it may be involved in the tubulogenesis and/or maintenance of duct-lumen architecture. Reduced PKHD1 levels in pck rat kidneys and its colocalization with polycystins may underlie the pathogenic basis for cystogenesis in polycystic kidney diseases.