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Biomedical subjects

Pei Zhou

Publications and source records attributed to Pei Zhou.

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

Rapid assignment of protein side chain resonances using projection-reconstruction of (4,3)D HC(CCO)NH and intra-HC(C)NH experiments.

The reconstruction of higher-dimensional NMR spectra from projections can provide significant savings in instrument time. Here, we demonstrate its application to the (4,3)D HC(CCO)NH and intra-HC(C)NH experiments. The latter experiment contains a novel intra-residue filter element, which selectively correlates the side chain resonances with the corresponding intra-residue amide resonances. Compared to the conventional HC(C)NH experiment, the intra-HC(C)NH experiment reduces the spectral complexity and thus the minimum number of projections required for artifact-free reconstruction by half. The use of the projection-reconstruction technique allows rapid data collection and unambiguous assignment of aliphatic side chain nuclei at high resolution.

Algorithms↗
PubMed2005

Screening on oil-decomposing microorganisms and application in organic waste treatment machine.

As an oil-decomposable mixture of two bacteria strains (Bacillus sp. and Pseudomonas sp.), Y3 was isolated after 50 d domestication under the condition that oil was used as the limited carbon source. The decomposing rate by Y3 was higher than that by each separate individual strain, indicating a synergistic effect of the two bacteria. Under the conditions that T = 25-40 degrees C, pH = 6-8, HRT (Hydraulic retention time) = 36 h and the oil concentration at 0.1%, Y3 yielded the highest decomposing rate of 95.7%. Y3 was also applied in an organic waste treatment machine and a certain rate of activated bacteria was put into the stuffing. A series of tests including humidity, pH, temperature, C/N rate and oil percentage of the stuffing were carried out to check the efficacy of oil-decomposition. Results showed that the oil content of the stuffing with inoculums was only half of that of the control. Furthermore, the bacteria were also beneficial to maintain the stability of the machine operating. Therefore, the bacteria mixture as well as the machines in this study could be very useful for waste treatment.

Bacteria↗
PubMed2005

[Determination of ginsenoside compound-K by reversed-phase high performance liquid chromatography].

Ginsenoside compound-K content in ginseng is very low, while it is the main intestinal bacterial metabolite and the final absorption style of the major components, such as ginsenosides Rbl and Rb2. The determination of ginsenoside compound-K in the fermentation liquor of ginseng saponins by reversed-phase high performance liquid chromatography was established. The separation was carried out under the following conditions: a Waters Symmetry C18 column (4.6 mm i.d. x 150 mm, 5 microm) was used at 35 degrees C with acetonitrile-water (48:52, v/v) as mobile phase at a flow rate of 1 mL/min. UV detection wavelength was set at 203 nm. The experimental results showed a good linear relationship between the peak area and mass concentration for ginsenoside compound-K within the range of 0.05-0.8 g/L (r = 0.9998). The relative standard deviation of peak area (n = 6) was 2.20%. The lowest detection limit (S/N = 3) was 2.5 mg/L. The average recoveries (n = 3) for the culture broth of ginseng saponins and notoginseng saponins were 98.6% and 99.7%, respectively. The method is rapid, simple, accurate and reproducible and can be utilized for the research and development of ginsenoside compound-K in pharmaceutical industry.

Chromatography, High Pressure Liquid↗
PubMed2005

[Preparation of nosiheptide liposomes and its inhibitory effect on hepatitics B virus in vitro].

AIM: To prepare liposomes of nosiheptide and study its ability to inhibit hepatitis B virus HBsAg and HBeAg secreted. METHODS: Liposomes of nosiheptide was prepared by sodium deoxycholate dialysis and sonication. Nosheptide was determined by HPLC and partical size was determined by using laser light scattering instrument. Transmission electron microscopy (TEM) was used to examine the morphology of liposomes. Its actions to inhibit hepatitis B virus HBsAg and HBeAg secreted was studied by a HBV-transfectted cell line (HepG2 2. 2. 15 ). RESULTS: Encapsulation efficiency of liposomes by chloroform:methanol (2:1, v/v) was higher than that by dioxane. With the increase of the ratio of nosiheptide: PC (W/W), the encapsulation efficiency of liposomes decreased with the increase of ratio of sodium deoxycholate: PC, the liposomes partical size decreased. The liposomes kept stable at -20 degrees C after 2 years. The drug concentrations of liposomes that inhibit HBsAg secreted by (46.9 +/- 2. 6) %, (55.4 +/- 1.2) %, (65 +/- 3) % and HBeAg secreted by (15.1 +/- 2.3) %, (36.2 +/- 1.7) %, (36.8 +/- 2.5) % were 1.25, 2.5, 5.0 microg x mL(-1), respectively. CONCLUSION: Liposomes of nosheptide can be prepared by sodium deoxycholate dialysis and sonication, which ability to inhibit hepatitis B virus HBsAg and HBeAg secreted is better than nosheptide.

Antiviral Agents↗
PubMed2004

Human acyl-coenzyme A:cholesterol acyltransferase 1 (acat1) sequences located in two different chromosomes (7 and 1) are required to produce a novel ACAT1 isoenzyme with additional sequence at the N terminus.

A rare form of human ACAT1 mRNA, containing the optional long 5'-untranslated region, is produced as a 4.3-kelonucleotide chimeric mRNA through a novel interchromosomal trans-splicing of two discontinuous RNAs transcribed from chromosomes 1 and 7. To investigate its function, we express the chimeric ACAT1 mRNA in Chinese hamster ovary cells and show that it can produce a larger ACAT1 protein, with an apparent molecular mass of 56 kDa on SDS-PAGE, in addition to the normal, 50-kDa ACAT1 protein, which is produced from the ACAT1 mRNAs without the optional long 5'-untranslated repeat. To produce the 56-kDa ACAT1, acat1 sequences located at both chromosomes 7 and 1 are required. The 56-kDa ACAT1 can be recognized by specific antibodies prepared against the predicted additional amino acid sequence located upstream of the N-terminal of the ACAT1(ORF). The translation initiation codon for the 56-kDa protein is GGC, which encodes for glycine, as deduced by mutation analysis and mass spectrometry. Similar to the 50-kDa protein, when expressed alone, the 56-kDa ACAT1 is located in the endoplasmic reticulum and is enzymatically active. The 56-kDa ACAT1 is present in native human cells, including human monocyte-derived macrophages. Our current results show that the function of the chimeric ACAT1 mRNA is to increase the ACAT enzyme diversity by producing a novel isoenzyme. To our knowledge, our result provides the first mammalian example that a trans-spliced mRNA produces a functional protein.

Amino Acid Sequence↗
PubMed2004

Nanocolloidal gold-based immunoassay for the detection of the N-methylcarbamate pesticide carbofuran.

Nanocolloidal gold particles were prepared and labeled to an anti-carbofuran monoclonal antibody (Mab). This conjugate was dispensed on the conjugated pad of a porous glass fiber. Ovalbumin (OVA)-carbofuran and goat anti-mouse IgG were dispensed on the nitrocellulose (NC) membrane and served as the test line and control line, respectively. The carbofuran-containing sample migrated to the NC membrane and reacted with the anti-carbofuran Mab labeled with the colloidal gold. The mixture diffused along the membrane and passed through the OVA-carbofuran in the test line via capillary action. The more analyte present in the sample, the more effectively it will compete with the carbofuran immobilized on the test line for binding to the limited amount of antibody labeled with colloidal gold. An adequate amount of carbofuran could prevent attachment of the colored conjugate to the test line. The presence or absence of a colored band on the test line could indicate a negative or positive result, respectively. When measured to the water sample spiked with carbofuran, this was obtained at or above 0.25 mg/L of carbofuran. The major advantages of the one-step strip test are that the detection time needed was <10 min and all of the reagents are included in the test device.

Antibodies, Monoclonal↗
PubMed2004

Generalized reconstruction of n-D NMR spectra from multiple projections: application to the 5-D HACACONH spectrum of protein G B1 domain.

Reconstructing multidimensional NMR spectra from 2-D projections significantly reduces the time needed for data collection over conventional methodology. Here, we provide a generalization of the projection-reconstruction process to spectra of arbitrary dimensionality, using a concept of coordinate rotation to produce explicit expressions for reconstruction. These expressions allow one to reconstruct subsets of the higher dimensionality space without producing the full spectrum, permitting convenient analysis of the data. We demonstrate the effectiveness of these procedures in the reconstruction of the 5-D HACACONH spectrum of protein G B1 domain from 12 2-D projections collected in five experiments. We further demonstrate that the base spectra of GFT-NMR are equivalent to projections of the 5-D spectrum at fixed angles.

Nerve Tissue Proteins↗
PubMed2004

Dynamics of fipronil residue in vegetable-field ecosystem.

Fipronil insecticide has been widely used to control vegetable pests in China recently. The research was conducted to evaluate the fate of fipronil in vegetable-field ecosystem and provide the scientific basis of using this insecticide. Developed on the analytical methods of fipronil residue and its four metabolisms, the degradation dynamics of their residue in a vegetable and the soil of the vegetable fields was studied. The results showed that (1) degradation of fipronil was faster in pakchoi (half-life 2.6 days) than in soil (half-life 7.3 days); (2) degradation reaction occurred in soil was governed mainly by photodegradation and oxidization accompanying with production of the metabolites, MB46513 and MB46136. Reduction and hydrolyzation played little role in the degradation process. In pakchoi, degradation was mainly contributed by reduction though oxidization and hydrolyzation occurred simultaneously. The metabolite products were MB45950, MB46136 and RPA200766; (3) the final residue in pakchoi was at a level of 0.003 mg kg(-1), which was much lower than the USA's upper limit of 0.04 mg kg(-1) in rice. Therefore, a dosage of 24 g hm(-2) was suggested and considered as safe to human beings and animals.

Biodegradation, Environmental↗
PubMed2004

Expression, purification, and characterization of His-tagged penicillin G acylase from Kluyvera citrophila in Escherichia coli.

The DNA fragment encoding Kluyvera citrophila penicillin G acylase (KcPGA) was amplified and cloned into the vector pET28b to obtain a C-terminus His-tagged fusion expression plasmid. The fusion protein KcPGA was successfully overexpressed in Escherichia coli BL21(DE3). The optimal induction concentration of isopropylthio-beta-D-galactoside (IPTG) was found to be 5 microM. The fusion protein was purified in a single step by Ni-IDA affinity chromatograph to a specific activity of 35.3U/mg protein with a final yield of 89% representing a 23-fold purification. The data presented here suggest that the purified fusion protein is stable with respect to pH and temperature. The optimal pH and temperature of recombinant KcPGA are 8.5 and 55 degrees C, respectively. The Km and Vmax are 17.6 microM and 23.8 U/mg, respectively. Therefore, the high yield and high specific activity of recombinant KcPGA produced in E. coli, together with other kinetic parameters, represent an excellent basis for further development of recombinant KcPGA as an immobilized biocatalyst for industrial applications.

Escherichia coli↗
PubMed2004

Enhancement of human ACAT1 gene expression to promote the macrophage-derived foam cell formation by dexamethasone.

In macrophages, the accumulation of cholesteryl esters synthesized by the activated acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT1) results in the foam cell formation, a hallmark of early atherosclerotic lesions. In this study, with the treatment of a glucocorticoid hormone dexamethasone (Dex), lipid staining results clearly showed the large accumulation of lipid droplets containing cholesteryl esters in THP-1-derived macrophages exposed to lower concentration of the oxidized low-density lipoprotein (ox-LDL). More notably, when treated together with specific anti-ACAT inhibitors, the abundant cholesteryl ester accumulation was markedly diminished in THP-1-derived macrophages, confirming that ACAT is the key enzyme responsible for intracellular cholesteryl ester synthesis. RT-PCR and Western blot results indicated that Dex caused up-regulation of human ACAT1 expression at both the mRNA and protein levels in THP-1 and THP-1-derived macrophages. The luciferase activity assay demonstrated that Dex could enhance the activity of human ACAT1 gene P1 promoter, a major factor leading to the ACAT1 activation, in a cell-specific manner. Further experimental evidences showed that a glucocorticoid response element (GRE) located within human ACAT1 gene P1 promoter to response to the elevation of human ACAT1 gene expression by Dex could be functionally bound with glucocorticoid receptor (GR) proteins. These data supported the hypothesis that the clinical treatment with Dex, which increased the incidence of atherosclerosis, may in part due to enhancing the ACAT1 expression to promote the accumulation of cholesteryl esters during the macrophage-derived foam cell formation, an early stage of atherosclerosis.

Arteriosclerosis↗
PubMed2004

Differentiation of hepatic tumors by color Doppler imaging: role of the maximum velocity and the pulsatility index of the intratumoral blood flow signal.

Doppler spectral analysis using color Doppler ultrasonography (US) was performed in a total of 133 patients with 135 hepatic tumors, including 88 hepatocellular carcinomas (HCCs), 30 metastatic hepatic cancers, 15 hemangiomas and 2 focal nodular hyperplasias (FNHs). Mean +/- SD of maximum velocity (Vmax) in hemangiomas (15.0 +/- 16.0 cm/s) was significantly lower than in HCCs (34.9 +/- 26.7 cm/s) and in metastases (37.9 +/- 17.4 cm/s). Mean +/- SD of the pulsatility index (PI) in hemangiomas (0.45 +/- 0.41) was significantly lower than in HCCs (1.52 +/- 0.71) and metastases (1.44 +/- 0.43). Mean +/- SD of Vmax and PI in FNH was 20.0 +/- 11.3 cm/s and 0.90 +/- 0.35, respectively. HCC showed a wide spectrum in terms of Vmax and PI; however, 18% of the HCC nodules had relatively high PI (>2.0). Specificity of Vmax more than >60 cm/s and PI more than 2.0 for the diagnosis of HCC were 92 and 94%, respectively. On the other hand, 87% of hemangiomas showed relatively lower Vmax (<30 cm/s) and 87% of hemangiomas showed relatively low PI (<1.0 cm/s). Specificity of Vmax less than 30 cm/s and PI less than 1.0 for the diagnosis of hemangioma were 47 and 78%, respectively. When taking account of both parameters, Vmax and PI, diagnostic efficacy for hemangioma and HCC was greatly improved (sensitivity, specificity, accuracy, positive predictive value and negative predictive value of 80, 86, 85, 41 and 97%, respectively, in hemangioma, and 38, 85, 54, 83 and 58%, respectively, in HCC) as compared with the results with Vmax or PI alone. In conclusion, in addition to the information obtained by Vmax, simultaneous measurement of PI adds valuable information useful in the noninvasive differentiation among hepatic tumors by Doppler spectral analysis at color Doppler US.

Adult↗
PubMed2004

Detection of intratumoral vascularity in small hepatocellular carcinoma by coded phase inversion harmonics.

OBJECTIVE: To investigate the value of contrast-enhanced coded phase inversion harmonic imaging (PIHI) in the depiction of intratumoral vascularity in small hepatocellular carcinoma (HCC). METHODS: Eighty-five patients with 106 HCCs < or =3 cm in diameter were evaluated with coded harmonic angio (CHA), a coded PIHI, with use of an intravenous contrast medium, Levovist. Intratumoral vessels were detected in the early arterial phase, and tumor parenchymal stain was demonstrated in the late vascular phase. The detectability of intratumoral vascularity on contrast-enhanced CHA was compared with that on dynamic computed tomography (CT) and digital subtraction angiography (DSA). RESULTS: With a combination of both vessel images and parenchymal flow images demonstrated by contrast-enhanced CHA, 98 of 106 small HCCs were evaluated as being hypervascular or isovascular. Using the results on dynamic CT as a gold standard, the sensitivity, specificity and accuracy were 95.1, 100 and 95.3%, respectively. The detection rate of intratumoral vascularity by contrast-enhanced CHA was 92.5% (98/ 106), compared with 97.2% (103/106) on dynamic CT (p = 0.14) and 88.9% (40/45) on DSA (p = 0.53). CONCLUSIONS: Contrast-enhanced coded PIHI is a sensitive tool for depicting intratumoral vascularity of small HCC.

Adult↗
PubMed2004

Hepatocellular carcinoma with nodule-in-nodule appearance: demonstration by contrast-enhanced coded phase inversion harmonic imaging.

OBJECTIVE: A nodule-in-nodule hemodynamic pattern, namely a vascular spot in a hypovascular nodule, is specific for the diagnosis of early-stage hepatocellular carcinoma (HCC). The purpose of this study was to assess whether this unique hemodynamic pattern can be detected by contrast-enhanced coded phase inversion harmonic imaging (PIHI). METHODS: 159 consecutive patients with HCC who underwent contrast-enhanced coded PIHI were retrospectively reviewed. Cases with nodule-in-nodule patterns were selected, and findings were compared with those on computed tomography (CT) angiography (CTA) and intraarterial contrast-enhanced ultrasonography (US angiography). RESULTS: Contrast-enhanced coded PIHI successfully displayed the nodule-in-nodule hemodynamic pattern in two cases of histologically proven HCC and the hemodynamic transition in one of the two cases, which corresponded well with findings on CTA and US angiography. CONCLUSIONS: Contrast-enhanced coded PIHI can demonstrate the special nodule-in-nodule hemodynamic pattern. It is useful in the diagnosis and follow-up of early-stage HCC or suspected nodules because of its noninvasiveness and easy performance.

Aged↗
PubMed2004

Characterization of hepatic tumors: value of contrast-enhanced coded phase-inversion harmonic angio.

OBJECTIVE: Our purpose was to evaluate the value of contrast-enhanced coded phase-inversion harmonic imaging in showing the characteristic intranodular hemodynamics of hepatic tumors. SUBJECTS AND METHODS. Using a microbubble contrast agent we performed coded harmonic angio in 163 patients with 192 hepatic tumor nodules: 153 hepatocellular carcinomas, 13 metastases, 14 hemangiomas, eight dysplastic nodules, and four focal nodular hyperplasias. After injecting Levovist, we performed real-time scanning, interval-delay fast low-angle shot imaging, and sweep scanning in the early arterial phase, late vascular phase, and postvascular phase, respectively. RESULTS: On contrast-enhanced coded harmonic angio, the typical hemodynamic pattern of hepatocellular carcinomas was shown as abundant tumor vessels supplied from the periphery to the center of the tumor and dense parenchymal tumor staining with fast washout (sensitivity, 92.8%; specificity, 92.3%). The characteristic hemodynamic pattern of metastases was peripheral tumor vessels with a rim parenchymal stain in the vascular phase followed by a perfusion defect in the postvascular phase (sensitivity, 69.2%; specificity, 100%). Hemangiomas were hypovascular in the early arterial phase with gradual spotty or cotton-wool pooling continuing to the late vascular phase (sensitivity, 92.9%; specificity, 100%). Dysplastic nodules were shown as having no early arterial supply with isovascularity in the late vascular phase (sensitivity, 75%; specificity, 100%). Focal nodular hyperplasias were shown to have a spoked wheel pattern of blood vessels accompanied by dense staining in interval-delay scanning (sensitivity, 100%; specificity, 100%). CONCLUSION: Contrast-enhanced coded harmonic angio is a promising method to provide useful information for the differential diagnosis of hepatic tumors.

Adult↗
PubMed2004

[Compared D-amino acid oxidase expression in different Pichia pastoris host strains].

To compare the DAAO expression level in different Pichia pastoris host strains, the gene encoding DAAO from Trigonopsis variabilis was cloned into plasmid pPIC3.5k and then transformed into P. pastoris GS115 and KM71 respectively. The positive transformants PDK13 (MutS) and PD27 (Mut+) were obtained by PCR analysis. Their optimal and different expression conditions were investigated. To compare with PD27, PDK13 was determined to poss a slower consumption of methanol, a longer induction time, a lower oxygen request and apparently higher expression of DAAO. The highest expression levels were reached up to 2700, 2500 IU/L in shaking flask and 10140, 8463.5 IU/L in fermentor respectively. The over-expression of DAAO can meet its large demand for production of 7-ACA, alpha-keto acid and L-amino acid. In addition, the phenylpyruvate and L-phenylalanine were obtained by crude DAAO reacting with DL-phenylalanine at 37 degrees C for 3h.

D-Amino-Acid Oxidase↗