Showing papers by "Sichuan University published in 2006"

Serum tumor markers for detection of hepatocellular carcinoma.

Abstract: Hepatocellular carcinoma (HCC) is one of the most frequent malignant tumors and is the second most common cause of cancer death in China. Therefore, it is very important to detect this disease and the recurrence at its earlier period. Serum tumor markers, as the effective method for detecting hepatocellular carcinoma for a long time, could be divided into 4 categories: oncofetal antigens and glycoprotein antigens; enzymes and isoenzymes; genes; and cytokines. Serum alpha fetoprotein (AFP) is the most widely used tumor marker in detecting patients with hepatocellular carcinoma, and has been proven to have capability of prefiguring the prognosis. However, it has been indicated that AFP-L3 and DCP excel AFP in differentiating hepatocellular carcinoma from nonmalignant hepatopathy and detecting small hepatocellular carcinoma. Some tumor markers, such as human cervical cancer oncogene and human telomerase reverse transcriptase mRNA, have also been indicated to have higher accuracies than AFP. Furthermore, some other tumor markers, such as glypican-3, gamma-glutamyl transferase II, alpha-l-fucosidase, transforming growth factor-beta1, tumor-specific growth factor, have been indicated to be available supplementaries to AFP in the detection. AFP mRNA has been shown to correlate with the metastasis and recurrence of HCC, and it may be the most useful marker to prefigure the prognosis. Some other markers, such as gamma-glutamyl transferase mRNA, vascular endothelial growth factor, and interleukin-8, could also be used as available prognostic indicators, and the simultaneous determination of AFP and these markers may detect the recurrence of HCC at its earlier period.

Update of PROFEAT: a web server for computing structural and physicochemical features of proteins and peptides from amino acid sequence

Abstract: Sequence-derived structural and physicochemical features have been extensively used for analyzing and predicting structural, functional, expression and interaction profiles of proteins and peptides. PROFEAT has been developed as a web server for computing commonly used features of proteins and peptides from amino acid sequence. To facilitate more extensive studies of protein and peptides, numerous improvements and updates have been made to PROFEAT. We added new functions for computing descriptors of protein-protein and protein-small molecule interactions, segment descriptors for local properties of protein sequences, topological descriptors for peptide sequences and small molecule structures. We also added new feature groups for proteins and peptides (pseudo-amino acid composition, amphiphilic pseudo-amino acid composition, total amino acid properties and atomic-level topological descriptors) as well as for small molecules (atomic-level topological descriptors). Overall, PROFEAT computes 11 feature groups of descriptors for proteins and peptides, and a feature group of more than 400 descriptors for small molecules plus the derived features for protein-protein and protein-small molecule interactions. Our computational algorithms have been extensively tested and used in a number of published works for predicting proteins of specific structural or functional classes, protein-protein interactions, peptides of specific functions and quantitative structure activity relationships of small molecules. PROFEAT is accessible free of charge at http://bidd.cz3.nus.edu.sg/cgi-bin/prof/protein/profnew.cgi.

Molecular functions and biological roles of hepatitis B virus x protein.

Abstract: Chronic infection of hepatitis B virus (HBV) is one of the major causes of hepatocellular carcinoma (HCC) in the world. Hepatitis B virus X protein (HBx) has been long suspected to be involved in hepatocarcinogenesis, although its oncogenic role remains controversial. HBx is a multifunctional regulator that modulates transcription, signal transduction, cell cycle progress, protein degradation pathways, apoptosis, and genetic stability by directly or indirectly interacting with host factors. This review focuses on the biological roles of HBx in HBV replication and cellular transformation in terms of the molecular functions of HBx. Using the transient HBV replication assay, ectopically expressed HBx could stimulate HBV transcription and replication with the X-defective replicon to the level of those with the wild one. The transcription coactivation is mainly contributing to the stimulatory role of HBx on HBV replication although the other functions may affect HBV replication. Effect of HBx on cellular transformation remains controversial and was never addressed with human primary or immortal cells. Using the human immortalized primary cells, HBx was found to retain the ability to overcome active oncogene RAS-induced senescence that requires full-length HBx. At least two functions of HBx, the coactivation function and the ability to overcome oncogene-induced senescence, may be cooperatively involved in HBV-related hepatocarcinogenesis.

Molecular designer self-assembling peptides

Abstract: Chemistry has generally been associated with inorganic and organic syntheses, metal-organic composites, coordinate metal chemistry, catalyses, block copolymer, coating, thin film, industrial surfactants and small-molecule drug development. That is about to change. Chemistry will also expand to the discovery and fabrication of biological and molecular materials with diverse structures, functionalities and utilities. The advent of biotechnology, nanotechnology and nanobiotechnology has accelerated this trend. Nature has selected and evolved numerous molecular architectural motifs at nanometer scale over billions of years for particular functions. These molecular nanomotifs can now be designed for new materials and nanodevices from the bottom up. Chemistry will again harness Nature's enormous power to benefit other disciplines and society. This tutorial review focuses on two self-assembling peptide systems.

Piezoelectric and ferroelectric properties of [Bi0.5(Na1−x−yKxLiy)0.5]TiO3 lead-free piezoelectric ceramics

Abstract: The piezoelectric and ferroelectric properties of [Bi0.5(Na1−x−yKxLiy)0.5]TiO3 (BNKLT-x∕y) lead-free piezoelectric ceramics were studied. The ceramics show excellent piezoelectric and ferroelectric properties, and the optimum properties measured are as follows: piezoelectric constant d33=231pC∕N, planar and thickness electromechanical coupling factors kP=41.0% and kt=50.5%, remanent polarization Pr=40.2μC∕cm2, and coercive field Ec=2.47kV∕mm, respectively. Polarization versus electric (P-E) hysteresis loops of the ceramics are well rectangle shaped, and the dependence of P-E loops on temperature reveals that the depolarization temperature Td of BNKLT-0.15∕0.075 ceramics, which simultaneously have good piezoelectric properties (d33=164pC∕N,kp=36.3%,kt=48.6%) and strong ferroelectricity (Pr=38.8μC∕cm2,Ec=3.73kV∕mm) at room temperature, is about 195 °C.

Liposomal quercetin efficiently suppresses growth of solid tumors in murine models.

Abstract: Purpose: Quercetin is a potent chemotherapeutic drug. Clinical trials exploring different schedules of administration of quercetin have been hampered by its extreme water insolubility. To overcome this limitation, this study is aimed to develop liposomal quercetin and investigate its distribution in vivo and antitumor efficacy in vivo and in vitro . Experimental Design: Quercetin was encapsulated in polyethylene glycol 4000 liposomes. Biodistribution of liposomal quercetin i.v. at 50 mg/kg in tumor-bearing mice was detected by high-performance liquid chromatography. Induction of apoptosis by liposomal quercetin in vitro was tested. The antitumor activity of liposomal quercetin was evaluated in the immunocompetent C57BL/6N mice bearing LL/2 Lewis lung cancer and in BALB/c mice bearing CT26 colon adenocarcinoma and H22 hepatoma. Tumor volume and survival time were observed. The mechanisms underlying the antitumor effect of quercetin in vivo was investigated by detecting the microvessel density, apoptosis, and heat shock protein 70 expression in tumor tissues. Results: Liposomal quercetin could be dissolved in i.v. injection and effectively accumulate in tumor tissues. The half-time of liposomal quercetin was 2 hours in plasma. The liposomal quercetin induced apoptosis in vitro and significantly inhibited tumor growth in vivo in a dose-dependent manner. The optimal dose of liposomal quercetin resulted in a 40-day survival rate of 40%. Quantitative real-time PCR showed that liposomal quercetin down-regulated the expression of heat shock protein 70 in tumor tissues. Immunohistochemistry analysis showed that liposomal quercetin inhibited tumor angiogenesis as assessed by CD31 and induced tumor cell apoptosis. Conclusions: Our data indicated that pegylated liposomal quercetin can significantly improve the solubility and bioavailability of quercetin and can be a potential application in the treatment of tumor.

Circadian gene mPer2 overexpression induces cancer cell apoptosis

Abstract: The Period2 gene, an indispensable component of the circadian clock, not only modulates circadian oscillations, but also regulates organic function. We examined whether overexpression of the mouse Period2 gene (mPer2) in tumor cells influences cell growth and induces apoptosis. Overexpression of PERIOD2 in the mouse Lewis lung carcinoma cell line (LLC) and mammary carcinoma cell line (EMT6) results in reduced cellular proliferation and rapid apoptosis, but not in NIH 3T3 cells. Overexpressed mPER2 also altered the expression of apoptosis-related genes. The mRNA and protein levels of c-Myc, Bcl-X(L) and Bcl-2 were downregulated, whereas the expression of p53 and bax was upregulated in mPER2-overexpressing LLC cells compared with control cells transferred with empty plasmid. Our results suggest that the circadian gene mPeriod2 may play an important role in tumor suppression by inducing apoptotic cell death, which is attributable to enhanced pro-apoptotis signaling and attenuated anti-apoptosis processes.

Remarkable aspects of unsaturation in trinuclear metal carbonyl clusters: the triiron species Fe3(CO)n (n = 12, 11, 10, 9).

Abstract: The trinuclear iron carbonyls Fe3(CO)n (n = 12, 11, 10, 9) have been studied by density functional theory using the B3LYP and BP86 functionals. The experimentally known C2v isomer of Fe3(CO)12, namely Fe3(CO)10(μ-CO)2, is found to be the global minimum below the unbridged D3h isomer analogous to the known structures for Ru3(CO)12 and Os3(CO)12. The lowest-energy isomer found for Fe3(CO)11 is Fe3(CO)9(μ3-CO)2 with iron−iron distances in the Fe3 triangle, suggesting the one double bond (2.460 A by B3LYP and 2.450 A by BP86) and two single bonds (2.623 A by B3LYP and 2.604 A by BP86) required to give each Fe atom the favored 18-electron configuration. Two different higher-energy dibridged structures Fe3(CO)9(μ2-CO)2 are also found for Fe3(CO)11. The lowest-energy isomer found for Fe3(CO)10 is Fe3(CO)9(μ3-CO) with equivalent iron−iron distances in the Fe3 ring (2.47 A by B3LYP or BP86). The lowest-energy isomer found for Fe3(CO)9 is Fe3(CO)6(μ-CO)3 with distances in the Fe3 triangle possibly suggesting one si...

Solubility of Multicomponent Systems in the Biodiesel Production by Transesterification of Jatropha curcas L. Oil with Methanol

Abstract: Biodiesel is manufactured by transesterification of animal fat or vegetable oil. The reactants (oil and methanol) and the products (fatty acid methyl ester and glycerol) are partially mutual soluble in the reaction process. Inter-solubility of the reaction components is essential data for the production design and process operation. In this work, the Jatropha curcas L. oil (oil) has been transesterified to give Jatropha curcas L. oil methyl ester (FAME). The inter-solubility of FAME + methanol + glycerol, oil + FAME + methanol, oil + glycerol + methanol, and oil + FAME + glycerol in the range from 298.15 K to 333.15 K has been conducted. Methanol is completely soluble in both FAME and glycerol but is not soluble in oil. With an increase in the mass fraction of FAME, the solubility of methanol in the oil + FAME phase increases. The transesterification reaction is carried out in the methanol phase, and as a result, the reaction shows an induction period. When FAME content increases to 70 %, the oil + methan...

Smart polymer fibers with shape memory effect

Abstract: In this study, a series of smart polymer fibers with a shape memory effect were developed. Firstly, a set of shape memory polyurethanes with varying hard-segment content were synthesized. Then, the solutions of the shape memory polyurethanes were spun into fibers through wet spinning. The thin films of the polyurethanes were considered to represent the nature of the polyurethanes. Differential scanning calorimetry tests were performed on both the thin films and the fibers to compare their thermal properties. Wide angle x-ray diffraction and small angle x-ray scattering techniques were applied to investigate the structure of the thin films and the fibers, and the structure change taking place in the spinning process was therefore revealed. The spinning process resulted in the polyurethane molecules being partially oriented in the direction of the fiber axis. The molecular orientation prompted the aggregation of the hard segments and the formation of hard-segment microdomains. The mechanical properties of the fibers were examined through tensile tests. The shape memory effect of the thin films and the fibers was investigated through a series of thermomechanical cyclic tensile tests. It was found that the fibers showed less shape fixity but more shape recovery compared with the thin films. Further investigations revealed that the recovery stress of the fibers was higher than that of the thin films. The smart fibers may exert the recovery force of shape memory polymers to an extreme extent in the direction of the fiber axis and therefore provide a possibility for producing high-performance actuators.

A Novel Intumescent Flame‐Retardant Polyethylene System

Abstract: A novel carbonization agent was synthesized and characterized. The flame retardancy and thermal behavior of a new IFR system with and without metal chelates for LDPE were investigated by LOI, UL-94 test, and TGA. Metal chelates can remarkably improve the flame retardant performance of intumescent systems according to the tested results of LOI values and UL-94 ratings because they can act both as inhibitors of radicals and as promoters of carbonization. The TG curves show that the amounts of residue of IFR-PE/metal chelate systems increase compared to those of PE and IFR-PE at temperatures ranging from 400 to 650 °C. The IFR-PE/metal chelate system can obviously reduce the amounts of decomposing products at higher temperatures and promotes the formation of carbonaceous charred layers. A LOI value of 29.8 and UL-94 V-0 rating could be achieved when the synthesized carbonization agent, APP, MP, and CoOSAwere added into LDPE.

Biodegradation of gallotannins and ellagitannins

Abstract: Nowadays, many researches have been made on gallotannin biodegradation and have gained great success in further utilization. Some of industrial applications of these findings are in the production of tannase, the biotransformation of tannic acid to gallic acid or pyrogallol and detannification of food and fodder. Although ellagitannins have the typical C–C bound which is more difficult to be degraded than gallotannins, concerted efforts are still in progress to improve ellagitannin degradation and utilization. Currently, more attention is mainly focused on intestinal microflora biodegradation of tannins especially ellagitannins which can contribute to the definition of their bioavailability for both human beings and ruminants. Also there have been endeavours to utilize the tannin-degrading activity of different fungi for ellagitannin-rich biomass, which will facilitate application of tannin-degrading enzymes in strategies for improving industrial and livestock production. Due to the complicated structures of complex tannins and condensed tannins, the biodegradation of them is much more difficult and there are fewer researches on them. Therefore, the researches on the mechanisms of gallotannin and ellagitannin biodegradation can result in the overall understanding to the biodegradation of complex tannins and condensed tannins. Biodegradation of tannins is in an incipient stage and further studies have to be carried out to exploit the potential of various tannins for largescale applications in food, fodder, medicine and tannery effluent treatment. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Flame retardancy of different-sized expandable graphite particles for high-density rigid polyurethane foams

Abstract: The effects of expandable graphite (EG) of different particle sizes, on the fire-retardant properties of high-density rigid polyurethane foam (RPUF) (0.45 g cm−3) were studied. Samples of EG with different particle sizes were obtained by pulverization in an ultra-high-speed mixer for 4 and 13 min, respectively. It was shown that as received (EG0) and 4 min pulverized EG (EG4) efficiently improved the fire-retardant properties of RPUF composites, while 13 min pulverized EG (EG13) did not. The char of the burned composites filled with EG0 and EG4 covered the whole surface of the samples and formed a complete physical barrier. This barrier material prevented combustible gases from feeding the flame and also isolated oxygen efficiently from the burning material. EG13 did not produce enough char to cover the whole surface of the burning sample, resulting in poor fire-retardant property of the RPUF composites. Thermal degradation tests of the foams by thermogravimetric analysis indicated that EG showed negligible effects on the thermal stability of the RPUFs. Copyright © 2006 Society of Chemical Industry

Organocatalytic and Stereoselective [3 + 2] Cycloadditions of Azomethine Imines with α,β‐Unsaturated Aldehydes

Abstract: Bipyrazolidin-3-one derivatives are biologically significant compounds and their importance has increased in the past decades. In this paper, the first stereoselective [3 + 2] dipolar cycloadditions of azomethine imines with alpha,beta-unsaturated aldehydes catalyzed by readily available alpha,alpha-diarylprolinol salts are reported, providing a facile route to the synthesis of various chiral bipyrazolidin-3-one derivatives under mild conditions. The organocatalyst 1g with strongly electron-withdrawing groups exhibited the best stereoselectivity (exo:endo up to 98:2, for exo product up to 97% ee), in the combination with trifluoroacetic acid.

Enantioselective construction of quaternary carbon centre catalysed by bifunctional organocatalyst.

Abstract: The bifunctional thiourea–tertiary amine derivatives of simple chiral diamines serve as highly enantioselective catalysts for the Michael addition of α-substituted cyanoacetates to vinyl sulfones, giving an efficient protocol for the construction of an all-carbon substituted quaternary stereocentre.

Targeting radioimmunotherapy of hepatocellular carcinoma with iodine (131I) metuximab injection : Clinical phase I/II trials

Abstract: Purpose: HAb18G/CD147 is a hepatocellular carcinoma (HCC)-associated antigen. We developed iodine ( 131 I) metuximab injection (Licartin), a novel 131 I-labeled HAb18G/CD147-specific monoclonal antibody F(ab') 2 fragment, and evaluated its safety, pharmacokinetics, and clinical efficacy on HCC in Phase I/II trials. Methods and Materials: In a Phase I trial, 28 patients were randomly assigned to receive the injection in 9.25-, 18.5-, 27.75-, or 37-MBq/kg doses by hepatic artery infusion. In a multicenter Phase II trial, 106 patients received the injection (27.75 MBq/kg) on Day 1 of a 28-day cycle. Response rate and survival rate were the endpoints. Results: No life-threatening toxic effects were found. The safe dosage was 27.75 MBq/kg. The blood clearance fitted a biphasic model, and its half-life was 90.56–63.93 h. In the Phase II trial, the injection was found to be targeted and concentrated to tumor tissues. Of the 73 patients completing two cycles, 6 (8.22%) had a partial response, 14 (19.18%) minor response, and 43 (58.90%) stable disease. The 21-month survival rate was 44.54%. The survival rate of progression-free patients was significantly higher than that of patients with progressive disease after either one or two cycles ( p p = 0.0019). Conclusion: Iodine ( 131 I) metuximab injection is safe and active for HCC patients.

Herbal medicines for treatment of irritable bowel syndrome

Abstract: Background Traditional herbal therapies have been used for a long time to treat gastrointestinal disorders including irritable bowel syndrome, and their effectiveness from clinical research evidence needs to be systematically reviewed. Objectives To assess the effectiveness and safety of herbal medicines in patients with irritable bowel syndrome. Search methods We searched the following electronic databases till July 2004: The Cochrane Library (CENTRAL), MEDLINE, EMBASE, AMED, LILACS, the Chinese Biomedical Database, combined with hand searches of Chinese journals and conference proceedings till end of 2003. No language restriction was used. Selection criteria Randomised controlled trials of herbal medicines compared with no treatment, placebo, pharmacological interventions were included. Data collection and analysis Data were extracted independently by two authors. The methodological quality of trials was evaluated using the components of randomisation, allocation concealment, double blinding, and inclusion of randomised participants. Main results Seventy-five randomised trials, involving 7957 participants with irritable bowel syndrome, met the inclusion criteria. The methodological quality of three double-blind, placebo-controlled trials was high, but the quality of remaining trials was generally low. Seventy-one different herbal medicines were tested in the included trials, in which herbal medicines were compared with placebo or conventional pharmacologic therapy. Herbal medicines were also combined with conventional therapy and compared to conventional therapy alone. Compared with placebo, a Standard Chinese herbal formula, individualised Chinese herbal medicine, STW 5 and STW 5-II, Tibetan herbal medicine Padma Lax, traditional Chinese formula Tongxie Yaofang, and Ayurvedic preparation showed significantly improvement of global symptoms. Compared with conventional therapy in 65 trials testing 51 different herbal medicines, 22 herbal medicines demonstrated a statistically significant benefit for symptom improvement, and 29 herbal medicines were not significantly different than conventional therapy. In nine trials that evaluated herbal medicine combined with conventional therapy, six tested herbal preparations showed additional benefit from the combination therapy compared with conventional monotherapy. No serious adverse events from the herbal medicines were reported. Authors' conclusions Some herbal medicines may improve the symptoms of irritable bowel syndrome. However, positive findings from less rigorous trials should be interpreted with caution due to inadequate methodology, small sample sizes, and lack of confirming data. Some herbal medicines deserve further examination in high-quality trials.

Local partial-likelihood estimation for lifetime data

Abstract: This paper considers a proportional hazards model, which allows one to examine the extent to which covariates interact nonlinearly with an exposure variable, for analysis of lifetime data. A local partial-likelihood technique is proposed to estimate nonlinear interactions. Asymptotic normality of the proposed estimator is established. The baseline hazard function, the bias and the variance of the local likelihood estimator are consistently estimated. In addition, a one-step local partial-likelihood estimator is presented to facilitate the computation of the proposed procedure and is demonstrated to be as efficient as the fully iterated local partial-likelihood estimator. Furthermore, a penalized local likelihood estimator is proposed to select important risk variables in the model. Numerical examples are used to illustrate the effectiveness of the proposed procedures.