Biomedical subjects

Qing Liu

Publications and source records attributed to Qing Liu.

At least 91 records · Page 5Linked to original sources

PubMed2004

Molecular cloning of novel cellulase genes cel9A and cel12A from Bacillus licheniformis GXN151 and synergism of their encoded polypeptides.

A thermophilic bacterial strain GXN151 which could degrade Avicel efficiently was isolated and identified as Bacillus licheniformis. A genomic library of GXN151 was constructed and two novel endoglucanase genes designated cel9A and cel12A were isolated by screening the library on carboxylmethyl cellulase indicator plates. The analysis of amino acid sequences deduced from the genes indicated that Cel9A consisted of a catalytic domain belonging to glycosyl hydrolase family 9, a linker domain, and a carbohydrate binding module family 3 from N-terminal to C-terminal; Cel12A had only one catalytic domain belonging to glycosyl hydrolase family 12. The combinations of Cel9A and Cel12A produced by the recombinant E. coli exhibited synergistic action against substrates of carboxylmethyl cellulose as well as Avicel.

Bacillus↗

PubMed2004

Regulation of the ubiquitin proteasome pathway in human lens epithelial cells during the cell cycle.

Most proliferating cells follow a series of orderly transitions from one phase to another. These transitions are usually controlled by timed degradation of cell cycle regulators by the ubiquitin-proteasome pathway (UPP). There are no published reports regarding the timing of phases of the human lens cell cycle or regarding cell cycle-related changes in UPP components. Objectives of this study were to characterize the timing of the phases of the human lens epithelial cell cycle and to explore potential functions of critical components of the UPP in controlling lens cell cycle. Human lens epithelial cells were synchronized at G0/G1 phase by contact inhibition. Cell cycle progression upon subculturing was monitored by FACS analysis. It took approximately 40 hr for HLEC to complete one cell cycle, approximately 20 hr for G1 phase, approximately 8-10 hr for S phase and approximately 10 hr for the combination of G2 and M phases. Proteasome-dependent degradation of p21WAF and p27Kip, the dominant Cdk inhibitors, was associated with the G1/S phase transition in these cells. Proteasome inhibition experiments indicate that proteolysis is the predominant process which is responsible for the variations in these regulators during the cell cycle. Levels of specific ubiquitin conjugating enzymes, Ubc7 and Ubc10, increased 6 and 2-fold at the G2/M phase and S/G2/M phases, respectively. Levels of these E2s decreased precipitously upon completion of the M phase. In contrast, levels of ubiquitin activating enzyme (E1) and Ubc3 remained constant during the cell cycle. Cul1, a component of the SCF (an E3), remained relatively constant during cell cycle. The up-regulation of Ubc7 and Ubc10 during the G2/M and S/G2/M phases suggests that these enzymes may be involved in controlling the cell cycle progression at this phase. Taken together, the data indicate that expression of key components of the UPP in the human lens epithelial cells is regulated in a cell cycle-dependent manner. Some of the variations in levels of ubiquitin conjugating enzymes are suggestive of previously undescribed functions.

Cell Cycle↗

PubMed2004

Isocyanate vapor-induced antigenicity of human albumin.

BACKGROUND: The bioreactivity of isocyanate, a leading cause of occupational asthma, has led to uncertainty regarding the chemical's antigenicity and mechanisms that elicit immunopathology. OBJECTIVE: To understand better the biologically relevant antigenic forms of hexamethylene diisocyanate (HDI), commonly used in the auto body industry. METHODS: Human albumin was exposed to HDI vapors through a novel approach designed to model the air-liquid interface of the human airway. Vapor HDI-exposed albumin was characterized by electrophoresis, chemical substitution analysis, mass spectrometry, and serology studies on auto body shop workers (N=203) and HDI asthmatics (N=11). RESULTS: HDI vapors caused significant changes in the shape and/or charge of human albumin, which differed from albumin exposed to liquid phase HDI, with lower isocyanate substitution ratios and distinct electrophoretic mobility. Specific sites of vapor HDI conjugation to albumin were identified at His(247) and Lys(414). Vapor HDI-exposed albumin was specifically recognized by the humoral arm of the human immune system, with a strong dependence on albumin as the carrier. Vapor HDI-exposed albumin-specific IgG titers were significantly associated with HDI exposure (P=.001), and specific IgE was detectable in 55% (6/11) of isocyanate asthmatics versus 1.5% (3/203) of exposed healthy workers. Parallel studies using HDI-exposed albumin conjugates produced by previously published methods showed less significant associations of HDI-specific IgG and IgE with exposure and disease, respectively. CONCLUSION: HDI-albumin conjugates produced by novel vapor phase exposure methods may be more physiologically relevant than those produced by previously published methods and of greater utility in characterizing the immune responses associated with HDI exposure and asthma.

Albumins↗

PubMed2004

Solvent effects on infrared spectra of methyl 4-hydroxybenzoate in pure organic solvents and in ethanol/CCl4 binary solvents.

Infrared spectroscopy studies of methyl 4-hydroxybenzoate (MHB) in 17 different organic solvents and in ethanol/CCl4 binary solvent were undertaken to investigate the solvent-solute interactions. The frequencies of carbonyl stretching vibration nu(C=O) of MHB in single solvents were correlated with the solvent acceptor number (AN) and the linear solvation energy relationships (LSER). The assignments of the two bands of nu(C=O) of MHB in alcohols and the single one of that in non-alcoholic solvents were discussed. The shifts of nu(C=O) of MHB in ethanol/CCl4 binary solvents showed that several kinds of solute-solvent hydrogen bonding interactions coexisted in the mixture solvents, with a change in the mole fraction of ethanol in the binary solvents.

Alcohols↗

PubMed2004

Solvent effect on infrared spectra of methyl methacrylate in CCl4/C6H14, CHCl3/C6H14 and C2H5OH/C6H14 binary solvent systems.

Research of methyl methacrylate (MMA) in three kinds of binary solvent systems (CCl4/C6H14, CHCl3/C6H14 and C2H5OH/C6H14) on the infrared (IR) spectra was reported. Two types of carbonyl stretching vibration bands for MMA in CHCl3/C6H14 or C2H5OH/C6H14 mixtures were found with the changing of the mole fraction of CHCl3 (XCHCl3) or C2H5OH (XC2H5OH). The carbonyl stretching vibration bands at lower frequencies in the above two mixtures were attributed to the formation of hydrogen bonding between MMA and CHCl3 or C2H5OH. While in CCl4/C6H14 mixtures there was only one type of carbonyl stretching vibration band of MMA. Good linear correlations between the frequencies of C=O or C=C stretching vibration band of MMA and XCCl4, XCHCl3 or XC2H5OH were found, respectively. The solute-solvent interactions in the three different binary solvent systems were discussed in detail.

Carbon Tetrachloride↗

PubMed2004

Infrared study on solvent-solute interactions of 2-acetylthiophene in binary mixtures.

The infrared absorption spectra of the carbonyl stretching vibrations of 2-acetylthiophene (AcTh) have been investigated in cyclo-hexane/alcohol mixtures (C6(12/C2H5OH; (6H12/n-C4H9OH; C6H12/i-C3H7OH and C6H12/t-C5H11OH). Five types of carbonyl stretching vibration bands for AcTh are found with the change of the mole fraction of the aprotic solvent C6H12 (x(C6H12)) in binary solvent mixtures. The dependencies of the frequencies of carbonyl stretching vibrations (nu(C=O)) on x(C6H12) allow a distinction and assignment of all species resulting from the solvent-solute interactions. Linear correlations between the nu(C=O) of each species and x(C6H12) are found. The influence on the transformation of some species caused by the self association of alcohols is discussed.

Alcohols↗

PubMed2004

NADPH oxidase-mediated generation of reactive oxygen species is critically required for survival of undifferentiated human promyelocytic leukemia cell line HL-60.

Nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) mediated generation of reactive oxygen species (ROS) was originally identified as the powerful host defense machinery against microorganism in phagocytes. But recent reports indicated that some non-phagocytic cells also have the NADPH oxidase activity, and the ROS produced by it may act as cell signal molecule. But as far as today, whether the NADPH oxidase also plays similar role in phagocyte has not been paid much attention. Utilizing the undifferentiated HL-60 promyelocytic leukemia cells as a model, the aim of the present study was to determine whether NADPH oxidase plays a role on ROS generation in undifferentiated HL-60, and the ROS mediated by it was essential for cell's survival. For the first time, we verified that the release of ROS in undifferentiated HL-60 was significantly increased by the stimulation with Calcium ionophore or opsonized zymosan, which are known to trigger respiration burst in phagocytes by NADPH oxidase pathway. Diphenylene iodonium (DPI) or apocynin (APO), two inhibitors of NADPH oxidase, significantly suppressed the increasing of ROS caused by opsonized zymosan. Cell survival assay and fluorescence double dyeing with acridine orange and ethidium bromide showed that DPI and APO, as well as superoxide dismutase (SOD) and catalase (CAT) concentration-dependently decreased the viability of undifferentiated HL-60 cells, whereas exogenous H2O2 can rescue the cells from death obviously. Our results suggested that the ROS, generated by NADPH oxidase play an essential role in the survival of undifferentiated HL-60 cells.

Acetophenones↗

PubMed2004

Novel mutations of the RNA-specific adenosine deaminase gene (DSRAD) in Chinese families with dyschromatosis symmetrica hereditaria.

Dyschromatosis symmetrica hereditaria (DSH) is an autosomal dominant skin disorder. It is also called "reticulate acropigmentation of Dohi" or "symmetric dyschromatosis of the extremities". The DSH locus has recently been mapped to chromosome 1q21 and pathogenic mutations were identified in the DSRAD gene encoding double-stranded RNA-specific adenosine deaminase in Japanese patients with DSH. We report here two novel point mutations, Q513X(1537C>T) and R916W(2746C>T) in the DSRAD gene identified in two Chinese families, respectively. These data suggest that mutations in DSRAD were also associated with DSH in Chinese. This is the first report on DSRAD as the causative gene of DSH in the Chinese population.

Adenosine Deaminase↗

PubMed2004

Differential regulation of components of the ubiquitin-proteasome pathway during lens cell differentiation.

PURPOSE: To investigate the role for the ubiquitin-proteasome pathway in controlling lens cell proliferation and differentiation and the regulation of the ubiquitin conjugation machinery during the differentiation process. METHODS: bFGF-induced lens cell proliferation and differentiation was monitored in rat lens epithelial explants by bromodeoxyuridine (BrdU) incorporation and expression of crystallins and other differentiation markers. Levels of typical substrates for the ubiquitin-proteasome pathway, p21(WAF) and p27(Kip), were monitored during the differentiation process, as were levels and activities of the enzymes involved in ubiquitin conjugation. RESULTS: Explants treated with bFGF initially underwent enhanced proliferation as indicated by BrdU incorporation. Then they withdrew from the cell cycle as indicated by diminished BrdU incorporation and accumulation of p21(WAF) and p27(Kip). bFGF-induced cell proliferation was prohibited or delayed by proteasome inhibitors. Lens epithelial explants treated with bFGF for 7 days displayed characteristics of lens fibers, including expression of large quantities of crystallins. Whereas levels of E1 remained constant during the differentiation process, the levels of ubiquitin-conjugating enzyme (Ubc)-1 increased approximately twofold, and the thiol ester form of Ubc1 increased approximately threefold on 7 days of bFGF treatment. Levels of Ubc2 increased moderately on bFGF treatment, and most of the Ubc2 was found in the thiol ester form. Although levels of total Ubc3 and -7 remained unchanged, the proportions of Ubc3 and -7 in the thiol ester form were significantly higher in the bFGF-treated explants. Levels of Ubc4/5 and -9 also increased significantly on treatment with bFGF, and more than 90% of Ubc9 was found in the thiol ester form in the bFGF-treated explants. In contrast, levels of Cul1, the backbone of the SCF type of E3s, decreased 50% to 70% in bFGF-treated explants. CONCLUSIONS: The data show that proteolysis through the ubiquitin-proteasome pathway is required for bFGF-induced lens cell proliferation and differentiation. Various components of the ubiquitin-proteasome pathway are differentially regulated during lens cell differentiation. The downregulation of Cul1 appears to contribute to the accumulation of p21(WAF) and p27(Kip), which play an important role in establishing a differentiated phenotype.

Animals↗

PubMed2004

[Characteristics of sublingual venae in primary liver cancer patients in different clinical stages].

OBJECTIVE: To explore the characteristics of the sublingual venae in patients with primary liver cancer (PLC). METHODS: The shape, color and the red, green and blue values of the sublingual venae were analyzed quantitatively for PLC patients in different clinical stages by analysis system for comprehensive information of tongue diagnosis. RESULTS: With the aggravating of the disease, the patients' sublingual venae became wide and tortuous, and their color became blue and purple. The abnormality of the sublingual venae was more serious in clinical stage III than in stages I and II (P < 0.05). CONCLUSION: The shape, color and abnormality degree of the sublingual venae in patients with PLC in different clinical stages are distinct.

Adult↗

PubMed2004

[Analysis of studies on pattern recognition of tongue image in traditional Chinese medicine by computer technology].

The article analyzed the contemporary study of pattern recognition of tongue images in traditional Chinese medicine by computer technology from its key sectors. It regards that the methods of orthogonal design and evaluation of image quality should be introduced to get a high-quality and practicable condition. In the field of tongue image segmentation, multiple methods used together are expected to improve the effect of segmentation. A scientific and canonical standard of tongue diagnosis based on comprehensive experts' experience with Delphi evaluation method and multi-center experts diagnosis on internet are also very essential. The study of pattern recognition on tongue image is still concentrated on the color. Further study should be extended to achieve quantification. And a comprehensive diagnosis on pattern recognition of tongue image is the aim that should be focused on later.

Diagnosis, Computer-Assisted↗

PubMed2004

[Suspending particulates in rotifer-culturing pond ecosystem].

A comparative study on the structure and dynamics of suspending particulates in static and current water rotifer-culturing ponds showed that the total content of suspending particulates varied from 6.76 to 65.39 mg.L-1, with an average of 11.50 mg.L-1 in static water ponds, among which, organic pariculates accounted for 66.8%, while inorganic particulartes occupied 33.2%. In the organic particulates, both particulate detritus and bacteria accounted for 31%, while phytoplankton and zooplankton occupied 30.5% and 5.3%, respectively. The amount of suspending particulates in current water ponds was 41.83 mg.L-1 in average, among which, organic pariculates accounted for 70.4%, while inorganic pariculates occupied 29.6%. In the organic pariculates, both particulate detritus and bacteria accounted for 39.2%, while phytoplankton and zooplankton occupied 30% and 1.2%, respectively. The content of suspending pariculates in static water ponds was less than those in current water ponds. Rotifer-culturing pond was a special type of ecosystem, where Brachionus plicatilis was the major consumer, its community structure was sample, and the abiotic factors were easy to be changed, which resulted in the dynamics of suspending pariculates content in ponds. The ratio of organic to total pariculates in rotifer-culturing ponds was higher, and the contents of both particulate detritus and bacteria were corresponding to that of plankton.

Animals↗

PubMed2004

[Treatment for erectile dysfunction patients with obstructive sleep apnea syndrome by nasal continual positive airway pressure].

OBJECTIVE: To investigate the influence of nasal continual positive airway pressure (nCPAP) on the erectile function of erectile dysfunction (ED) patients with obstructive sleep apnea syndrome(OSAS). METHODS: Twenty-seven patients with ED and OSAS were randomly divided into treatment (n = 15) and control (n = 12) groups, the former treated by nCPAP from 22:00 to 6:00 per night for 1 month. And the apnea-hypopnea index(AHI), the lowest oxygen saturation (SaO2) and IIEF were compared before and after treatment. RESULTS: AHI, the lowest SaO2, erectile function and IIEF showed no significant difference before treatment in the two groups, but displayed a significant improvement after treatment in the treated group compared with the control (P > 0.05), in which no significant changes were observed before and after treatment (P > 0.05). CONCLUSION: nCPAP therapy can improve the erectile function of ED patients with OSAS.

Adult↗

PubMed2004

[Influence of vacuum bag on direct measurement of depth for isocentric posterior oblique field].

BACKGROUND & OBJECTIVE: In order to improve quality assurance (QA) and quality control (QC) of radiotherapy, individualized vacuum bag is used in the localization of radiation treatment, gradually becoming one of the important steps for the QA and QC in the many departments of radiation oncology. It is controversial whether localization with vacuum bags under the simulator influences the precision of direct measurement for tumor depth in the isocentric posterior oblique field in the patients with thoracic and abdominal tumors. This study was designed to explore the influence of vacuum bag on the direct measurement METHODS: Twenty-nine patients with thoracic and abdominal carcinoma who had to need isocentric irradiation in the supine position were immobilized using vacuum bag. The irradiation depths of 45 posterior oblique fields were determined by CT-simulator and conventional simulator, respectively; then the absolute value for the difference of both depths was regarded as error value. RESULTS: There were 37 fields (82.2%) with error value of smaller than 5 mm; 8 fields (17.8%), more than 5 mm. In the latter, 5 field were belonged to be repositioned in the phase II of radiotherapy because of light leaking air into the vacuum bag in the phase I of radiotherapy. CONCLUSION: Vacuum bag has a slight influence on direct measurement for depths of isocentric posterior oblique field.

Adolescent↗

PubMed2004

[Dynamics of biomass and stem volume of Picea asperata stands in artificial restoration process of subalpine coniferous forest].

The dynamics of aboveground biomass and stem volume in subalpine coniferous Picea asperata plantations with different stand ages in 70 years of artificial restoration process were studied by adopting the concept of space as a substitute for time. The results indicated that before 20 years of stand age, the biomass of spruce single tree grew quite slow, with that of the twigs and needles accounting for about 50%; after 20 years, it increased obviously, with 60% of biomass accumulated in stem; from 30 to 40 years, the increasing rate of biomass relatively slowed down, and maintained a rapid growth after 40 years. The biomass of spruce population showed a similar trend, though the period of relative slow-down of growth continued from 30 to 50 years. For the biomass of community as a whole, it presented a general continuous increase, but varied greatly for different layers. In shrub layer, the biomass rose rapidly at the early stage of plantation establishment and gradually decreased after 20 years, while that of the herbaceous plants reduced continuously and accounted less than 0.2% of the total biomass of community when the stand reached 70 years. Both the mean annual increment and the current annual increment of stem volume of spruce single tree went up with the increasing stand age, and more rapidly at the later stages. Similar changes were observed for the stock volume of the plantations, with the only difference that the current annual increment from 30 to 50 years was relatively reduced. Based on the data from stem analysis and growth ring measurement, regression models of stem volume with DBH and tree height of 70 years Picea asperata plantation were established.

Biomass↗

PubMed2004

[Polymorphism analysis of human cytomegalovirus UL148 gene in low passage clinical isolates].

BACKGROUND: To investigate the polymorphism of human cytomegalovirus UL148 gene in low passage clinical isolates and to study the relationship between the polymorphism and different pathogenesis of congenital HCMV infection. METHODS: PCR was performed to amplify the entire HCMV UL148 gene region of 38 clinical isolates, which had been proven containing detectable HCMV-DNA by using FQ-PCR.PCR amplification products were sequenced directly and the sequence data were analysed. RESULTS: Seventeen of 38 isolates were amplified successfully. By comparison with Toledo sequence, the length of UL148 ORFs in all 17 clinical isolates was similar to that of Toledo. Amino acid variability rate of UL148 protein was 0.3%-2.3%. There were additional or deleted sites of posttranslational modification of UL148 protein in all clinical isolates. CONCLUSION: All DNA and deduced amino acid sequences of UL148 gene shared great similarity among HCMV clinical strains regardless of their polymorphism.

Amino Acid Sequence↗

PubMed2004

[Dynamics of species diversity in artificial restoration process of subalpine coniferous forest].

Through plot investigation and by adopting the concept of space as a substitute for time, the developments of species diversity of trees, shrubs and herbaceous plants in subalpine coniferous plantations at different restoration stages were studied, and the correlation coefficients of species in each layer were discussed. The results indicated that in the restoration process, the species richness, diversity and evenness in subalpine coniferous plantations were gradually increased in a fluctuating way. The restoration process of Picea asperata plantations showed a tendency of development that in favor of resuming species diversity. The indices of species richness (species number and Margalef index) and species diversity (Shannon-Wiener index and Simpson index) of trees increased rapidly from the early stages of plantation establishment to the stage of canopy closing (about 30 yr of stand age) and then presented a tendency of decrease with some slight fluctuations, while the index of species evenness showed a periodical rising trend. For the shrub layer, the indices of species richness (Simpson index and Macintosh index) gradually increased with increasing restoration years, whereas the indices of species diversity (Shannon-Wiener index) decreased in the early stages, sharply increased during the stages of canopy closing, and then slowly decreased, which exhibited a tendency of high-->low-->high. In the layer of herbaceous plants, the indices of species richness (Margalef index and number of species) and species diversity (Simpson index, Macintosh index and Shannon-Wiener index) presented a trend of decrease in the early stages of plantations establishment to canopy closing and increased later on. During this process, herbaceous species and their life forms changed greatly, with shade tolerant species gradually substituting the intolerant species. Among the plantations of different stand ages, the average correlation coefficients of trees, shrubs and herbaceous species were 41.88%, 50.61% and 37.22%, respectively, indicating that in the 70 years of artificial forest restoration, the continuity and stability of shrub species were the highest, those of herbaceous species showed greatest fluctuation because of the disappearance and regeneration occurred with the alteration of the environmental conditions of plantations, and those of the trees were intermediary.

Altitude↗

PubMed2004

[Clonal architecture and ramet population characteristics of Lysimachia congestiflora growing under different light conditions].

The response of clonal architecture and ramet population characteristics to resource heterogeneity is of great ecological significance. This paper studied the variations of clonal architecture and ramet population characteristics of stoloniferous herb Lysimachia congestiflora growing at the open land of forest edge, forest edge, and forest understory of evergreen broad-leaved forest in Mt. Lingyan of Dujiangyan, Sichuan Province, and compared the stolon internode length, frequency distribution of stolon internode length, braching intensity, branching angle, frequency distribution of branching angle, ramet population density, ramet population height, ramet population biomass, and root/shoot of ramet population among the three habitats. The results showed that the stolon internode length, branching intensity, ramet population density and ramet population biomass were different among three habitats. Kruskal Wallis test indicated that the distributions of stolon internode length and branching angle were significantly different among three habitats. The skewness in distribution of stolon internode length was in the order of open land of forest edge>forest edge>forest understory; and the branching angle, ramet population height, and root/shoot of ramet population were significant greater in open land of forest edge than in forest edge and forest understory. The skewness in distribution of branching angle in open land of forest edge was smaller than that in forest edge and forest understory. The branching angle, ramet population height, and root/shoot of ramet population were not significantly different between forest edge and forest understory. These results were discussed in the context of resource acquisition strategy by clonal plants.

Analysis of Variance↗