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Biomedical subjects

T Jiang

Publications and source records attributed to T Jiang.

At least 19 recordsLinked to original sources
PubMed2006

Sensory-specific satiety with simple foods in humans: no influence of BMI?

OBJECTIVE: Olfacto-gustatory sensory-specific satiety plays an important role in the termination of food ingestion. A defect in this mechanism, by increasing food intake, could be a factor in development of overweight. The present study was conducted to explore whether sensory-specific satiety in the overweight may be different from that in normal-weight subjects. SUBJECTS: 144 subjects (half men, half women; age range: 17-62 years; BMI range: 17-39 kg m(-2)). MEASUREMENTS: Olfactory pleasure (OP) and flavor pleasure (FP) were evaluated before and after ingestion of a single chosen food. Six foods from three classes were offered: cucumber and tomato, pineapple and banana, and peanut and pistachio. According to the subjects' preference for one of them, subjects were classified into six groups (24 subjects each with equal sex ratio). The experimental sequence was (1) evaluation of the six foods (OP), (2) ad libitum intake of the preferred food (FP) and (3) second evaluation of the six foods (OP). RESULTS: Food intake was limited by sensory-specific satiety (that is, a decline in FP for the ingested food) in overweight subjects just as it was in the leanest. There was no significant correlation between BMI and hedonic parameters (OP and FP) or intakes (quantity and volume). Pre-ingestive OP and FP correlated with the ingested food's weight (OP: r=0.468; FP: r=0.415; P<0.01), volume (OP: r=0.428; FP: r=0.407; P<0.01) and intake duration (OP: r=0.184; FP: r=0.343; P<0.05). The decline in OP, but not in FP, correlated with ingested weight (r=0.271, P<0.01) and volume (r=0.263, P<0.01) but not with duration. CONCLUSION: After intake of a single food, olfacto-gustatory sensory-specific satiety correlated with the ingested food's weight and volume and with the duration of ingestion, but not with bodyweight. This suggests that overweight and lean subjects have similar hedonic control of food intake with simple foods.

Adolescent↗
PubMed2006

The 44 kDa Pim-1 kinase directly interacts with tyrosine kinase Etk/BMX and protects human prostate cancer cells from apoptosis induced by chemotherapeutic drugs.

Protein kinase Pim-1 has been implicated in the development of hematopoietic and prostatic malignancies. Here, we present the evidence that two isoforms, the 44 and 33 kDa Pim-1, are expressed in all human prostate cancer cell lines examined. The subcellular localization of human 44 kDa Pim-1 is primarily on the plasma membrane, while the 33 kDa isoform is present in both the cytosol and nucleus in PCA cells. The 44 kDa Pim-1 contains the proline-rich motif at the N-terminus and directly binds to the SH3 domain of tyrosine kinase Etk. Such interaction leads to the activation of Etk kinase activity possibly by competing with the tumor suppressor p53. This is corroborated by the fact that overexpression of the 44 kDa Pim-1 in prostate cancer cells confers the resistance to chemotherapeutic drugs. Our results suggest that these two isoforms of Pim-1 kinase may regulate distinct substrates and the 44 kDa Pim-1 may play a more prominent role in drug resistance in prostate cancer cells.

Amino Acid Sequence↗
PubMed2005

Paircoil2: improved prediction of coiled coils from sequence.

We introduce Paircoil2, a new version of the Paircoil program, which uses pairwise residue probabilities to detect coiled-coil motifs in protein sequence data. Paircoil2 achieves 98% sensitivity and 97% specificity on known coiled coils in leave-family-out cross-validation. It also shows superior performance compared with published methods in tests on proteins of known structure.

Algorithms↗
PubMed2005

A novel optical biosensor format for the detection of clinically relevant TP53 mutations.

The TP53 gene has been the subject of intense research since the realisation that inactivation of this gene is common to most cancer types. Numerous publications have linked TP53 mutations in general or at specific locations to patient prognosis and therapy response. The findings of many studies using general approaches such as immunohistochemistry or sequencing are contradictory. However, the detection of specific mutations, especially those occurring in the structurally important L2 and L3 zinc binding domains, which are the most common sites of TP53 mutations, have been linked to patient prognosis and more strongly to radiotherapy and chemotherapy resistance in several major cancers. In this study, the TI-SPR-1 surface plasmon resonance system and Texas Instruments Spreeta chips were used to develop a DNA biosensor based on thiolated probes complementary to these domains. The sensors were able to detect these mutations in both oligonucleotides and PCR products with normal and mutant TP53 DNA, but the difference in hybridisation signal was small. Preliminary experiments to enhance the signal using Escherichia coli mismatch repair proteins, MutS and single strand binding protein were carried out. It was found that MutS was unable to bind to mismatch oligonucleotides, but single strand binding protein was able to bind to single stranded probes, which had not hybridised to the target, resulting in a three-fold increase in the sensitivity of the biosensor. While further work needs to be carried out to optimise the system, these preliminary experiments indicate that the TI-SPR-1 can be used for the detection of clinically relevant mutations in the TP53 gene and that the sensitivity can be increased significantly using single strand binding protein. This system has a number of advantages over current mutation detection technologies, including lower cost, ease of sensor preparation and measurement procedures, technical simplicity and increased speed due to the lack of need for gel electrophoresis.

Biosensing Techniques↗
PubMed2005

The phylogeny of Chinese indigenous pig breeds inferred from microsatellite markers.

A genetic study of 32 local Chinese, three foreign pig breeds [Duroc (DU), Landrace and Yorkshire], and two types of wild boar (Hainan and Dongbei wild boar) based on 34 microsatellite loci was carried out to clarify the phylogeny of Chinese indigenous pig breeds. The allele frequencies, effective numbers of alleles, and the average heterozygosity within populations were calculated. The results showed that the genetic variability of the Lingao pig was the largest, while the Jiaxing pig was the lowest. The greatest distance between domestic pigs was found between Shanggao and DU pig and the shortest was found between Wuzhishan and Lingao pig, respectively. A neighbour-joining tree constructed from Modified Cavalli-Sforza genetic distances divided Chinese pigs into two clusters; four subclusters were also identified. Our results only partly agree with the traditional types of classification and also provide a new relationship among Chinese local pig breeds. Our data also confirmed that Chinese pig breeds have a different origin from European/American breeds and can be utilized in programmes that aim to maintain Chinese indigenous pig breeds.

Alleles↗
PubMed2005

Optimising the operation of a MBR pilot plant by quantitative analysis of the membrane fouling mechanism.

In order to optimize some operational conditions of MBR systems, a MBR pilot plant equipped with a submerged hollow fibre membrane module was employed in this study. The pilot MBR was fed with real municipal wastewater and the filtration flux, backwashing interval, aeration frequency and temperature were varied. A filtration flux below 25 I/m2h is generally recommended, at below this flux, the MBR operated at sub-critical flux conditions, the filter cake was minimized and membrane fouling was mainly attributed to the membrane pore blocking. Moreover, the membrane fouling, at below 25 I/m2h, was more reversible to backwashing; above this value, backwashing became less efficient to clean the membrane. Less frequent backwashing (e.g. 600 s filtration/45 s backwashing) decreased the amount of fouling irreversible to backwashing and its performance was superior to that of frequent backwashing (e.g. 200 s filtration/15 s backwashing). The MBR suffered more fouling at low temperature conditions (e.g. at 13-14 degrees C) than at high temperature conditions (e.g. at 17-18 degrees C). A conceptual model was built up and successfully interpreted this temperature effect.

Bacteria, Aerobic↗
PubMed2005

Calibrating a side-stream membrane bioreactor using Activated Sludge Model No. 1.

Membrane bioreactors (MBRs) are attracting global interest but the mathematical modeling of the biological performance of MBRs remains very limited. This study focuses on the modeling of a side-stream MBR system using the Activated Sludge Model No. 1 (ASM1), and compares the results with the modeling of traditional activated sludge processes. ASM1 parameters relevant for the long-term biological behaviour in MBR systems were calibrated (i.e. Y(H) = 0.72 gCOD/gCOD, Y(A) = 0.25 gCOD/gN, b(H) = 0.25 d(-1), b(A) = 0.080 d(-1) and f(p) = 0.06), and generally agreed with the parameters in traditional activated sludge processes, with the exception that a higher autotrophic biomass decay rate was observed in the MBR. Influent wastewater characterization was proven to be a critical step in model calibration, and special care should be taken in characterizing the inert particulate COD (X(I)) concentration in the MBR influent. It appeared that the chemical-biological method was superior to the physical-chemical method. A sensitivity analysis for steady-state operation and DO dynamics suggested that the biological performance of the MBR system (the sludge concentration, effluent quality and the DO dynamics) are very sensitive to the parameters (i.e. Y(H), Y(A), b(H), b(A) micro(maxH) and micro(maxA), and influent wastewater components (X(I), S(s), X(s) and S(NH)).

Biomass↗
PubMed2004

Therapeutic effects of dengue 2 virus capsid protein and staphylococcal nuclease fusion protein on dengue-infected cell cultures.

Dengue infection poses a serious public health problem in most tropical and subtropical areas. No effective antiviral drugs or vaccines are currently available against dengue infection. To explore the feasibility of using capsid-targeted viral inactivation (CTVI) as an antiviral strategy against dengue infection, we constructed a plasmid expressing a fusion protein consisting of staphylococcal nuclease (SN) fused to dengue 2 virus capsid protein (D2C), and investigated its effects on the production of infectious virions when introduced into BHK cells infected with dengue virus. The results indicated that D2C-SN can be expressed and tolerated in this mammalian cell culture. The enzymatically active SN moiety was incorporated into nascent virions during the process of viral assembly. By comparing the effects of incorporated SN and SN*, an enzymatically inactive missense mutant form of wild-type SN, on the infectivity of progeny virions, we clearly demonstrated that nucleolytic activity was the major antiviral mechanism. Expression of D2C-SN fusion protein as a therapeutic agent resulted in a reduction in infectious titers of 12- to 60-fold. Therefore, dengue virus may be particularly vulnerable to a CTVI therapeutic approach.

Animals↗
PubMed2004

Operon prediction by comparative genomics: an application to the Synechococcus sp. WH8102 genome.

We present a computational method for operon prediction based on a comparative genomics approach. A group of consecutive genes is considered as a candidate operon if both their gene sequences and functions are conserved across several phylogenetically related genomes. In addition, various supporting data for operons are also collected through the application of public domain computer programs, and used in our prediction method. These include the prediction of conserved gene functions, promoter motifs and terminators. An apparent advantage of our approach over other operon prediction methods is that it does not require many experimental data (such as gene expression data and pathway data) as input. This feature makes it applicable to many newly sequenced genomes that do not have extensive experimental information. In order to validate our prediction, we have tested the method on Escherichia coli K12, in which operon structures have been extensively studied, through a comparative analysis against Haemophilus influenzae Rd and Salmonella typhimurium LT2. Our method successfully predicted most of the 237 known operons. After this initial validation, we then applied the method to a newly sequenced and annotated microbial genome, Synechococcus sp. WH8102, through a comparative genome analysis with two other cyanobacterial genomes, Prochlorococcus marinus sp. MED4 and P.marinus sp. MIT9313. Our results are consistent with previously reported results and statistics on operons in the literature.

ATP-Binding Cassette Transporters↗
PubMed2003

Upregulation of Fas and FasL expression in testosterone-induced apoptosis of macrophages.

To the best of the authors' knowledge, there have been few reports on the effect of testosterone on the apoptosis of macrophages. In this report, we studied the effect of testosterone on the apoptosis of bone marrow-derived macrophages (BMMs) and the function of the Fas/Fas ligand (FasL) system in the process. Results showed that testosterone treatment in vitro at the physiological concentration of 10 nM did not induce the apoptosis of BMMs. However, BMMs underwent apoptosis when treated at higher concentrations of testosterone (100, 200 and 400 nM). Testosterone-induced apoptosis was associated with the enhanced expression of Fas, FasL, and caspase-8. These data suggest that the Fas/FasL system may play an important role in the testosterone-induced apoptosis of macrophages.

Animals↗
PubMed2002

Direct-method-aided phasing of MIR diffraction data from proteins.

Direct methods have successfully been used to break the phase ambiguity intrinsic in the single isomorphous replacement (SIR) data of proteins. Based on this, the procedure 'direct-method-aided MIR phasing' (DMIR) has been proposed and applied to the four-derivative multiple isomorphous replacement (MIR) data of a known protein containing 682 amino acid residuals in the asymmetric unit. The data set consists of 14,500 unique reflections at 3 A resolution with F(obs.) greater than 2sigma. Test calculation showed that the phases from conventional MIR phasing could be significantly improved by direct methods leading to obvious improvement in the quality of the resultant Fourier maps.

Crystallography, X-Ray↗
PubMed2002

Testosterone and estradiol modulate TNF-alpha-induced expression of adhesion molecules in endothelial cells.

Cytokine-activated endothelial expression of adhesion molecules plays an important role in immune responses. In the present study, we investigated the influences of testosterone and 17 beta-estradiol on tumor necrosis factor-alpha (TNF-alpha)-induced expression of adhesion molecules in human umbilical vein endothelial cells (HUVEC). HUVEC were incubated with TNF-alpha, testosterone or 17 beta-estradiol separately, or in a combination of TNF-alpha plus testosterone or 17 beta-estradiol. The expression of E-selectin, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) was evaluated at 3, 6, 12 and 24 h following exposure by flow cytometric analysis. The results showed that although testosterone or 17 beta-estradiol did not affect the expression of these adhesion molecules in unstimulated HUVEC, both of them transiently increased the expression of E-selectin and VCAM-1 in TNF-alpha stimulated HUVEC. Neither testosterone nor 17 beta-estradiol affected the expression of ICAM-1 induced by TNF-alpha. It is concluded that both testosterone and 17 beta-estradiol increase TNF-alpha-induced expression of E-selectin and VCAM-1 in endothelial cells and these facts might indicate a mechanism by which gonadal hormones can indirectly enhance immune responses.

Cells, Cultured↗
PubMed2001

Protective effect of green tea against benzo[a]pyrene-induced mutations in the liver of Big Blue transgenic mice.

We assessed the ability of green tea to protect against benzo[a]pyrene (B[a]P)-induced mutations in the liver of lacI transgenic male C57BL/6 Big Blue mice. The mice were given a 2% Japanese green tea hot water extract as their sole source of drinking water for 10 weeks. After 7 weeks, they received a total dose of 150 mg/kg B[a]P. Treatment with B[a]P resulted in a two-fold higher lacI mutant frequency than the untreated controls (8.6+/-0.8 x 10(-5) versus 4.0+/-0.7 x 10(-5), P=0.01). B[a]P increased the frequency of its characteristic mutation (GC-->TA transversions) nearly five-fold, from 0.75 x 10(-5) to 3.7 x 10(-5). In mice treated with green tea, the induced B[a]P mutant frequency decreased by 63%, while GC-->TA transversions were reduced by 54%. Thus, we report evidence that green tea extract significantly suppressed B[a]P-induced mutation by lowering its specific transversion mutation in the lacI transgene in vivo. Further studies will address the correlation between the modulation of metabolic enzymes and the protection against induced mutation by green tea.

Animals↗
PubMed2001

Oxidized low-density lipoprotein downregulates endothelial basic fibroblast growth factor through a pertussis toxin-sensitive G-protein pathway: mediator role of platelet-activating factor-like phospholipids.

BACKGROUND: Oxidized LDL (oxLDL) inhibits angiogenesis in part by downregulating endothelial basic fibroblast growth factor (bFGF). To determine the mechanism of the downregulation, we investigated the signal transduction pathway involving potential phospholipid mediators. METHODS AND RESULTS: Cultured bovine aortic endothelial cells were incubated with PBS (lipoprotein-free control), LDL, or copper oxLDL under serum-free conditions. At 24 hours, oxLDL (50 microg/mL) decreased bFGF mRNA (Northern blot), bFGF protein (Western blot and ELISA), and concomitant DNA synthesis, all by 40% to 50% compared with PBS. LDL had no effect. Pretreating the cells with 100 ng/mL pertussis toxin (PTX) for 18 hours before oxLDL exposure almost completely blocked the inhibitory effects of oxLDL. In contrast, inhibiting other major cellular signal transduction pathways with PD-98059 (mitogen-activated protein kinase kinase inhibitor), HA-1004 (inhibitor of cGMP- and cAMP-dependent protein kinase), or Ro-31-8220 (protein kinase C inhibitor) or chelating intracellular Ca(2+) with BAPTA-AM failed to attenuate any of the oxLDL effects assayed. Addition to the cultures of WEB 2086, a specific antagonist of the PTX-sensitive G protein-coupled platelet-activating factor (PAF) receptor, blocked the action of oxLDL. Whereas PAF dispersed in the culture medium failed to produce oxLDL-like effects, degradation of PAF and PAF-like phospholipids accumulated in oxLDL with a recombinant human PAF acetylhydrolase eliminated the inhibitory effects of oxLDL on bFGF expression and DNA synthesis. CONCLUSIONS: OxLDL suppresses endothelial bFGF expression and DNA synthesis through a PTX-sensitive heterotrimeric G-protein pathway involving mediator phospholipids similar, but not identical, to PAF.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed2001

Preparation and characterization of monolithic polymer columns for capillary electrochromatography.

A series of micro-monolithic columns with different porosities were prepared for capillary electrochromatography (CEC) by in-situ copolymerization of butyl methacrylate, ethylene glycol dimethacrylate, and 2-acrylamido-2-methyl-1-propane-sulfonic acid in the presence of a porogen in fused-silica capillaries of 100 microm I.D. Different column porosities were obtained by changing the ratios of monomers to porogenic solvents. Columns were investigated and evaluated under both pressure-driven (high-performance liquid chromatography, HPLC) and electro-driven (capillary electrochromatography, CEC) conditions. Each column exhibited different efficiency and dependency on flow velocity under electro-driven conditions. Abnormally broad peaks for some relatively bulky molecules were observed. Possible explanations are discussed. The differences in column efficiency and retention behavior between the two eluent-driven modes were studied in detail. In addition, other column properties, such as morphology, porosity, stability and reproducibility, were extensively tested.

Chromatography↗
PubMed2001

[Clinical observation of the microanatomical relation between pituitary stalk and pituitary adenoma].

OBJECTIVE: To observe the microanatomical relation between the pituitary stalk and pituitary adenoma so as to find practical approach to protect the pituitary stalk during operation. METHODS: At the level of diaphragm sellae, the laterality of pituitary stalk was assessed in 71 cases by its location to the line connecting the mid-points of tuberculum sellae and dorsum sellae. In 46 cases the level of diaphragma sellae was regarded as the clock dial so as to determine the location by hour of the pituitary stalk. RESULTS: The laterality of pituitary stalk was observed in 61 cases, among which the pituitary stalk was on the left side in 17 cases, on the right side in 41 cases, and at the posterior middle site in 13 cases. Location by hour was observed in 46 cases, among which 13 cases were at 5 o'clock, 11 at 6 o'clock, 7 at 7 o'clock, 5 at 4 o'clock, 4 at 3 o'clock, 2 at 2 o'clock, 2 at o'clock, and 2 at 11 o'clock respectively. CONCLUSION: The location of pituitary stalk is related to the direction of growth of tumor in the sella and not related to its extension above the sella. The pituitary stalk can be used as the marker to find normal pituitary tissue.

Adenoma↗