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Hui Cao

Publications and source records attributed to Hui Cao.

At least 37 records · Page 2Linked to original sources
PubMed2005

[Determination of the catalytic structures of methyl parathion hydrolase].

Methyl parathion hydrolase (MPH) is a novel member of organophosphorus hydrolase. In this study, mpd gene was expressed in Escherichia coli DH5alpha with its native promoter. MPH was purified to homogeneity. Results show that metal-chelating compounds cannot inhabit the enzyme activity. Inductively Coupled Plasma-Atomic Emission Spectrometry analysis showed that MPH is a zinc-containing enzyme, the Zinc to enzyme molar ratio is near 2:1. In order to investigate critical residues related to enzymatic activity of MPH, chemical modification reagents EDC, DEPC, butanedione and pyridoxal were tested. Experiment results suggested that aspartate, glutamate, arginine and lysine are not important for enzyme activity. But DEPC, which can modify histidine residue, inactivate the enzyme activity greatly, and the inactivation rate is 9.6 h(-1). This result reflects that histidine residues are essential for enzyme activity. All these results provide basic data for MPH structure and molecular evolution research.

Aryldialkylphosphatase↗
PubMed2005

[Community succession patterns of pests and natural enemies in jujube orchard ecosystem].

Through investigation and by the methods of optimal partitioning, principal component analysis, and one-or two-dimensional ordination, this paper analyzed the main groups and succession trends of the pest and natural enemy communities at a jujube orchard of Taigu area. The results showed that the communities had more obvious dominant factors and temporal succession pattern. The first three principal components of the communities had a bigger variation, with an obvious follow effects. The community succession was temporally divided into four stages, i. e., in the periods of pre-budding, leaf expanding and blooming, fruiting, and maturing. The dominant species of pests and their natural enemies were demonstrated.

Animals↗
PubMed2005

Mining a clinical data warehouse to discover disease-finding associations using co-occurrence statistics.

This paper applies co-occurrence statistics to discover disease-finding associations in a clinical data warehouse. We used two methods, chi2 statistics and the proportion confidence interval (PCI) method, to measure the dependence of pairs of diseases and findings, and then used heuristic cutoff values for association selection. An intrinsic evaluation showed that 94 percent of disease-finding associations obtained by chi2 statistics and 76.8 percent obtained by the PCI method were true associations. The selected associations were used to construct knowledge bases of disease-finding relations (KB-chi2, KB-PCI). An extrinsic evaluation showed that both KB-chi2 and KB-PCI could assist in eliminating clinically non-informative and redundant findings from problem lists generated by our automated problem list summarization system.

Chi-Square Distribution↗
PubMed2004

Effects of localization and amplification on intensity distribution of light transmitted through random media.

We numerically study the statistical distribution of intensity of light transmitted through quasi-one-dimensional random media by varying the dimensionless conductance g and the amount of absorption or gain. A markedly non-Rayleigh distribution is found to be well fitted by the analytical formula of Phys. Rev. Lett. 74, 2674 (1995)] with a single parameter g(') . We show that in the passive random system g(') is uniquely related to g , while in amplifying or absorbing random media g(') also depends on the gain or absorption coefficient.

Journal Article↗
PubMed2004

Chaotic microlasers based on dynamical localization.

We report the direct observation of lasing action from a dynamically localized mode in a microdisk resonator with rough boundary. In contrast to microlasers based on stable ray trajectories, the performance of our device is robust with respect to the boundary roughness and corresponding ray chaos, taking advantage of Anderson localization in angular momentum. The resonator design, although demonstrated here in GaAs-InAs microdisk laser, should be applicable to any lasers and sensors based on semiconductor or polymer materials.

Journal Article↗
PubMed2004

Comparing gene discovery from Affymetrix GeneChip microarrays and Clontech PCR-select cDNA subtraction: a case study.

BACKGROUND: Several high throughput technologies have been employed to identify differentially regulated genes that may be molecular targets for drug discovery. Here we compared the sets of differentially regulated genes discovered using two experimental approaches: a subtracted suppressive hybridization (SSH) cDNA library methodology and Affymetrix GeneChip technology. In this "case study" we explored the transcriptional pattern changes during the in vitro differentiation of human monocytes to myeloid dendritic cells (DC), and evaluated the potential for novel gene discovery using the SSH methodology. RESULTS: The same RNA samples isolated from peripheral blood monocyte precursors and immature DC (iDC) were used for GeneChip microarray probing and SSH cDNA library construction. 10,000 clones from each of the two-way SSH libraries (iDC-monocytes and monocytes-iDC) were picked for sequencing. About 2000 transcripts were identified for each library from 8000 successful sequences. Only 70% to 75% of these transcripts were represented on the U95 series GeneChip microarrays, implying that 25% to 30% of these transcripts might not have been identified in a study based only on GeneChip microarrays. In addition, about 10% of these transcripts appeared to be "novel", although these have not yet been closely examined. Among the transcripts that are also represented on the chips, about a third were concordantly discovered as differentially regulated between iDC and monocytes by GeneChip microarray transcript profiling. The remaining two thirds were either not inferred as differentially regulated from GeneChip microarray data, or were called differentially regulated but in the opposite direction. This underscores the importance both of generating reciprocal pairs of SSH libraries, and of real-time RT-PCR confirmation of the results. CONCLUSIONS: This study suggests that SSH could be used as an alternative and complementary transcript profiling tool to GeneChip microarrays, especially in identifying novel genes and transcripts of low abundance.

Dendritic Cells↗
PubMed2004

Determination of the stable conformation of GABA(A)-benzodiazepine receptor bivalent ligands by low temperature NMR and X-ray analysis.

The stable conformations of GABA(A)-benzodiazepine receptor bivalent ligands 2 and 3 were determined by low temperature NMR spectroscopy and confirmed by single crystal X-ray analysis. The linear conformation was important for these dimers to access the binding site and exhibit potent in vitro affinity as illustrated for alpha5 subtype selective ligand 2 (15 nM). Bivalent ligand 3 with the 5 atom linker folded back upon itself both in solution and in the solid state, moreover, it did not bind to Bz receptors.

Crystallography, X-Ray↗
PubMed2004

[Alterations in expression of F-actin and DNA of fluid shear stress treated-mesenchymal stem cells affected by titanium particles loading].

Particulate wear debris within the bone-prosthesis microenvironment generated by normal wear and corrosion of orthopaedic implants is considered to be one of the main factors responsible for chronic aseptic inflammation and development of osteolysis in the long-term instability and failure of total joint arthroplasty. While the decrease in bone volume caused by wear debris-induced osteolysis could have been compensated by enough new bone matrix secreted by osteoblasts. Actually, the normal osteoblastic population depend on the regular differentiation and proliferation of their progenitor cells--bone marrow mesenchymal stem cells (MSCs). This study aims to investigate the potential mechanism for the rat MSCs cytotoxicity upon exposure to Titanium (Ti) particles. Rat mesenchymal stem cells (rMSCs) isolated from 3-month-old male Sprague-Dawley rats by Percoll intensity gradient method were cultured in DMEM medium (low glucose) supplemented with 10% fetal bovine serum, 100 U/ml penicillin, and 100 micrograms/ml streptomycin in a humidified incubator with 5% CO2 at 37 degrees C. In order to gain the homogenous cell population, rMSCs were passaged to 3-4th subpassage which were used in all the experiment groups. Then rMSCs were seeded in the 6 well culture plates and exposed to three different circle diameters (mean size, TD1: 0.9 micron, TD2: 2.7 microns, TD3: 6.9 microns) with three different concentrations (0.1 wt%, 0.05 wt%, 0.01 wt%, W/V) at different durations (8 h, 16 h, 24 h,), respectively. Unexposed rMSCs were used as control. In the given periods of Ti loading, fluid shear stress (FSS) was applied to each group cells. The expression of F-actin and DNA of the rMSCs at the indicated time were determined with laser confocal scanning microscopy and image analysis software. The results showed that there was up-regulation expression of F-actin in the rMSCs without Ti particles loading but in the presence of FSS. Ti particles loading can suppress the expression of F-action and DNA of rMSCs, but this down-regulation response varied with the three circle diameter, concentrations and durations of Ti particles. Among three kinds of diametrically different Ti particles, submicron Ti particles (0.9 micron) had the greatest suppressive response on rMSCs, together with some apoptosis bodies. Under the same diameter condition, the inhibition induced by Ti particles loading was in a manner dependent on the particles concentration and exposure duration. The reductive effects produced from 0.1 wt% Ti was the greatest and earliest among the responses from Ti particles at three different concentrations; and the lower the concentration, the weaker the repressive influence. Furthermore, with the elongation of exposure to Ti particles, the expression of F-actin and DNA decreased gradually, the lowest level was at 32 h. These findings demonstrated that Ti particles loading can attenuate rMSCs' viability in a manner dependent on the circle diameter, particles concentration, treatment period, suggesting that a reduction in the number of viable MSCs together with a compromise of the their differentiation into functional osteoblast may exacerbate aseptic loosening of total joint implant. Further investigation into particles-mediated suppression of MCSs viability may reveal novel mechanism of implant loosening and aid in development and application of osteolytic drug therapy and the optimization of design and selection of future orthopaedic biomaterials, thereby improving long-term compatibility and stability for arthroplasty patients.

Actins↗
PubMed2004

[Effect of titanium particles loading on the viability of mesenchymal stem cells after osteoblastic induction].

OBJECTIVE: To assess the effect of titanium particles on the proliferation of rMSCs after osteoblastic induction. METHODS: MTT-assay and Confocal Laser Scanning Microscopy are utilized to detect rMSCs' proliferation rate and morphologic variety. RESULTS: It was found that Ti particles loading suppressed the proliferation of osteogenesis behavior of rMSCs, but the down-regulation effect varied in different circle diameter, different concentration and different loading duration of Ti particles. Especially, among three different particles, the submicron Ti particles (0.9 micron) had the most suppressive effect on rMSCs. Under the same diameter condition, the inhibitory effect induced by Ti particles loading showed a manner dependent on the particles concentration and exposure duration. The reductive response from 1 g/L Ti was the earliest and most intense one to come forth. And the lower the concentration was in use, the weaker would be the reductive response. Furthermore, with the elongation of exposure to Ti particles, proliferation was steadily decreasing and its lowest level was at 32 h of exposure. CONCLUSION: These findings demonstrated that Ti particles loading could suppress the viability of rMSCs' osteoblastic differentiation in a manner dependent on the circle diameter, particles concentration, and treatment time.

Animals↗
PubMed2004

[Effect of organophosphorous insecticides on Chinese chive insect pests and their degradation by pesticide-degrading bacterium].

3.00 kg(a. i) x hm(-2) phoxin and 2.63 kg(a. i) x hm(-2) methyl parathion were respectively applied to control the Taeniothrips alliorum on Chinese chive. Compared to no pesticide treatment, the decline rate of the insect density was 98.28% and 98.39% at the 3rd day after spraying pesticides, and 89.94% and 94.04% at the 20th day after spraying pesticides, respectively. At the 3rd day after spraying 15.00, 18.00 and 21.00 kg(a. i) x hm(-2) phoxin, the insect density of Bradysia odoriphaga decreased 80.77%, 93.10% and 96.98%, and at the 35th day after spraying, it decreased 92.44%, 95.05% and 96.81%, respectively. The application of pesticide-degrading bacterium had not any effect on controlling insect pests, but could markedly degrade pesticide. At the 3rd day after spraying 45.00 L x hm(-2) pesticide-degrading bacterium to control Taeniothrips alliorum, the degradion rate of phoxin and methyl parathion was 99.52% and 98.83%, and at the 3rd after spraying 75.00 L x hm(-2) pesticide-degrading bacterium to control Bradysia odoriphaga, the degradation rate of three concentrations of phoxin was 100%, 100% and 99.69%, respectively.

Animals↗
PubMed2004

Assessment the genetic diversity of Auricularia strains by two PCR-based typing methods.

Two PCR-based methods, enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) and randomly amplified polymorphic DNA (RAPD), were adopted for differentiating Auricularia strains. Taken the similarity coefficient as 75%, 29 strains of three Auricularia species were grouped into 6 and 9 clusters by RAPD and ERIC, respectively. The dendrogram from ERIC exhibited two distinct parts, one representing A. auricula and the other A. polytricha, but the dendrogram from RAPD failed to clearly distinguish between these two species. However, both methods similarly revealed high homology between A. fuscosuccinea and A. auricula. The homology relationships among the three species obtained from ERIC were validated by Southern hybridization. The analyses showed that RAPD is able to differentiate mainly at the species level, while ERIC is effective at the strain level and therefore more consistent with cultivation characteristics. The results indicate that the method of ERIC-PCR is more rapid and reliable than RAPD, and may substitute for RAPD in research related to the genetic identification and genetic diversity in Auricularia.

Agaricales↗
PubMed2003

Synthesis, in vitro affinity, and efficacy of a bis 8-ethynyl-4H-imidazo[1,5a]- [1,4]benzodiazepine analogue, the first bivalent alpha5 subtype selective BzR/GABA(A) antagonist.

The synthesis and in vitro affinity of the alpha5beta3gamma2 (alpha5) subtype selective BzR/GABA(A) antagonist 7 is described. This ligand is selective for alpha5 subtypes in vitro and is a potent antagonist of the effects of diazepam only at alpha5beta3gamma2 subtypes (oocytes). Ligands such as 7 will be important in the determination of which physiological function(s) are subserved by this GABA(A) alpha5 subtype.

Animals↗
PubMed2003

Temporal response of a random medium from speckle intensity frequency correlations.

We reconstruct the temporal response of a random medium by using speckle intensity frequency correlations. When the scattered field from a random medium is described by circular complex Gaussian statistics, we show that third-order correlations permit retrieval of the Fourier phase of the temporal response with bispectral techniques. Our experimental results for random media samples in the diffusion regime are in excellent agreement with the intensity temporal response measured directly with an ultrafast pulse laser and a streak camera. Our speckle correlation measurements also demonstrate sensitivity to inhomogeneous samples, highlighting the potential application for imaging within a scattering medium.

Journal Article↗
PubMed2003

The role of vasoactive substances in hyperhemodynamics after orthotopic liver transplantation in cirrhotic rats.

OBJECTIVE: To evaluate the role of endogenous vasoactive substances in hyperdynamic circulation after orthotopic liver transplantation (OLT) in cirrhotic rats. METHODS: Male SD rats were randomly divided into 4 groups: normal controls (NL, n = 10), rats with intrahepatic portal hypertension (IHPH, n = 10), normal rats with OLT (NL-OLT, n = 9), and IHPH rats with OLT (IHPH-OLT, n = 16). IHPH-OLT rats were divided into 2 subgroups: Group A (3 days after OLT, n = 9) and Group B (7 days after OLT, n = 7). IHPH was induced by injection of CCI(4) and OLT was performed using cuffs for the anastomosis of suprahepatic inferior vena cava, infrahepatic vena cava and portal vein. Radioactive microsphere method was used for hemodynamic study. The concentrations of plasma glucagon (Glu), nitric oxide (NO), prostaglandin (PGI(2)), thromboxaneA(2) (TXA(2)) and endothelin (ET) were measured by radioimmunoassay. RESULTS: No significant difference in hemodynamic changes was observed between NL-OLT and NL rats, except for mean arterial blood pressure. No significant changes in NO and PGI(2) were seen between NL-OLT and NL rats. Glu, ET and TXA(2) were significantly elevated in NL-OLT rats compared with NL rats (P < 0.05). Characteristics of systemic and splanchnic hyperdynamic circulatory states were observed in IHPH, IHPH-OLT A, IHPH-OLT B rats. Both the magnitude of hyperhemodynamics and increasing concentrations of Glu and NO occurred in the order of IHPH > IHPH-OLT A > IHPH-OLT B rats. The level of plasma PGI(2) in IHPH rats was significantly elevated compared with NL rats, while PGI(2) in IHPH-OLT A and B rats was found to be lower than in IHPH rats (P < 0.05). There was no obvious difference in PGI(2) between IHPH-OLT B and NL rats. Vasoconstrictors including ET and TXA(2) were found elevated in IHPH-OLT rats. CONCLUSIONS: OLT does not induce postoperative hyperhemodynamics per se. Vasodilators including NO and Glu, especially NO, play an important role in the hyperhemodynamics of IHPH and IHPH-OLT rats. The results of the present study demonstrate that the persistence of systemic and splanchnic hyperkinetic circulation in the early stages after OLT may result from those non-eliminated factors that caused hyperhemodynamics in liver cirrhosis patients with portal hypertension before OLT.

Animals↗
PubMed2003

[Two chemotypes of Pogostemon cablin and influence of region of cultivation and harvesting time on volatile oil composition].

AIM: To analyze and compare the constituents of the volatile oil of Pogostemon cablin collected from different regions of cultivation and harvesting times in order to evaluate the quality of Shipai Huoxiang and to expound the chemical intension of Pogostemon cablin. METHODS: The combination of GC and MS. RESULTS: The volatile oil compositions of Herba Pogostemonis collected from various of cultivation regions and harvesting times are obviously different. Based on the chemical differences of the volatile oil compositions, Pogostemon cablin is divided into two chemotypes, Pogostone-type and Patchouliol-type. The former was cultivated in Guangzhou and Gaoyao regions, locally named as "Shipai Huoxiang"; the latter was locally named as "Hainan Huoxiang", cultivated in Wuchuan, Suixi and Leizhou regions of Guangdong Province and Wanning region of Hainan Province. The Pogostone-type contains rich oxygenated components, especially pogostone in the volatile oil compositions and poor non-oxygenated composition with patchouliol. The above chemical data may be used as evaluation standard for the authentic Shipai Huoxiang. The Patchouliol-type contains similar quantities of oxygenated and non-oxygenated composition, especially rich patchouliol with poor pogostone in oxygenated compositions, rich delta-guaiene and alpha-guaiene in non-oxygenation compositions. The contents of volatile oil and their constituents were varied due to different harvesting time. The yields of pogostone and volatile oil of Shipai Huoxiang was higher in July. The quality of the samples collected in this month was better. CONCLUSION: According to the volatile oil compositions, there are two chemotypes (Pogostone-type and Patchouliol-type) in Pogostemon cablin plant. These two chemotypes correspond to the genotypes of plastid matK gene and nuclear 18s rRNA gene by cluster analysis.

Ecosystem↗
PubMed2003

[The effect of PGI2 on formation and development of hyperdynamic circulatory state in portal hypertensive rats].

OBJECTIVE: To investigate the effects of prostacyclin (PGI(2)) and nitric oxide (NO) in the development of hyperdynamic circulatory state on chronic portal hypertensive rats. METHODS: Sixty-six male SD rats were divided into three groups, namely intrahepatic portal hypertension (IHPH) by injection of CCl(4), prehepatic portal hypertension (PHPH) by partial stenosis of the portal vein for 2 weeks and sham-operated controls (SO). Animals in each group were divided further into 3 subgroups and received N(omega)-nitro-L-arginine (L-NNA), indomethacin and saline (as control), respectively. Splanchnic and systemic hemodynamics was measured using radioactive microsphere techniques. The NO concentration in serum was determined by nitrates-nitrites which were measured using a colorimetric method, and concentration of PGI(2) was determined using specific radioimmunoassay for its stable hydrolytic product, 6-keto-PGF(1 alpha). RESULTS: The concentrations of plasma 6-keto-PGF(1 alpha) and serum nitrates + nitrites in IHPH rats (1 123.85 +/- 153.64; 73.34 +/- 4.31) and in PHPH rats (891.88 +/- 83.11; 75.21 +/- 6.89) were significantly higher than those of SO rats (725.53 +/- 105.54;58.79 +/- 8.47). L-NNA and indomethacin could decrease the concentrations of plasma 6-keto-PGF(1 alpha) and serum nitrates + nitrites in IHPH and PHPH rats (P < 0.05). At the same time, CI, FPP and PVI were lowered while MAP, TPR and SVR were increased (P < 0.05). After deduction of NO action, there were no significant correlation between plasma PGI(2) level and hemodynamic parameters such as CI, TPR, PVI and SVR. However, after deduction of PGI(2) action, NO was still correlated highly with those hemodynamic parameters. CONCLUSION: It is NO rather then PGI(2) that is a mediator in the formation and development of hyperdynamic circulatory state in chronic portal hypertensive rats.

6-Ketoprostaglandin F1 alpha↗