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Biomedical subjects

Ying Li

Publications and source records attributed to Ying Li.

At least 217 records · Page 12Linked to original sources
PubMed2005

[High-level expression of an extreme-thermostable xylanase B from Thermotoga maritima MSB8 in Escherichia coli and Pichia pastoris].

The family 10 xylanase (XynB) from Thermotoga maritima MSB8 is extremely thermostable and great potential in the applications of various fields of industry. The gene mxynB(64) was amplified by the method of PCR with the template of the genomic DNA of Thermotoga maritima MSB8, and cloned into the expression vectors of Escherichia coli and Pichia pastoris respectively. Xylanase B(40kD) was successfully expressed by the two heterologous protein expression systems with high-level production. The recombinant protein of XynB expressed in Pichia pastoris showed extreme thermostability and pH stability, which was optimally active at 90 degrees C and quite stable over the pH range of pH 5.0-10.8 at 70 degrees C. After incubation of the enzyme at 100 degrees C for 30 min, XynB retained 70% higher residual activity. The recombinant XynB expressed in Pichia pastoris is of great use in a variety of industrial and agricultural applications.

Endo-1,4-beta Xylanases↗
PubMed2005

[Pilot experiment of fluorine fixing ratio of coated lump stone coal fuel].

The pilot experiment on coated lump stone coal fuel selected from 16 families in Haoping Shanxi were studied. 8 families burned coating high fluorine lump stone coal with lime, clay and low fluorine anthracite, 8 families burned untreated lump stone coal. The results show that the fluorine-fixing ratio at treated group was 75.0% when coal fluorine compared with coal cinder fluorine. In comparison with untreated group, the concentration of door air fluoride lowered 85.7%, SO2 lowered 75.0%, dust lowered 55.3%.

Air Pollution, Indoor↗
PubMed2005

[The study of protoporphyrin IX metabolism in cell proliferation using yolk as the target samples].

In order to find the better target sample to investigate protoporphyrin IX metabolism in the cell proliferation process in chick embryos, the emission spectra of egg white, yolk and urine from non-incubated and incubated eggs were measured under the excitation at 405 nm. It was observed that, among the three components investigated, only yolk sample was possible to get in pureness almost through the whole incubation process. Furthermore, compared with the egg white, the yolk had more obvious characteristic emission of protoporphyrin IX and lower background spectra and turned to be the better target sample for the investigation. The relative characteristic emission intensity of PpIX of yolk samples was used to determine the level of PpIX metabolism. It was found that the relative emission intensity increases during the first 10 days of proliferation process, indicating an increase in the concentration or in the metabolism level of protoporphyrin IX. The relative emission intensity, hence the PpIX metabolism level, then decreased gradually during the rest days of proliferation process. These results are similar to those obtained on human malignant tumors as they develop. The result testifies the point of view further that the abnormity of PpIX metabolism is correlative to the rapid limitless cell proliferation.

Animals↗
PubMed2005

[Effect of MAb225 on radiosensitivity of Tca8113 tongue squamous cell carcinoma].

OBJECTIVE: The purpose of this study was to invest the effect of epidermal growth factor receptor monoclonal antibody MAb225 on radiosensitivity of tongue squamous cell carcinoma cell Tca8113. METHODS: Tca8113 cells were treated with different concentrations of MAb225. Radiation dose survival curve was generated from clonogenic survival assay. SERPD0 and survival faction (SF2) was analysed by single hit multi-target (SHMT) radiobiological model using RADMEDIC software. Nude mice with Tca8113 tumor xenografts were treated with MAb225, radiation treatment or both of them. Tumor responses were assessed by tumor growth delay, and t test was used for statistical analysis. RESULTS: MAb225 enhanced the radiosensitivity of Tca8113 cells. SERD0 of Tca8113 cells treated with 0.5 mg/L MAb225 was 1.23. The survival fraction of cells treated with MAb225 was significantly decreased. Tumor radioresponse could be enhanced by MAb225 (P < 0.05). CONCLUSION: MAb225 could enhance radiosensitivity of tongue squamous cell carcinoma cell.

Animals↗
PubMed2005

[Factors associated with responses of telephone screening interview in a validity and reliability study of telephone interview to assess dietary intake in urban China].

OBJECTIVE: To describe the first phase of a multi-phase study exploring the possibility of conducting telephone dietary intake interviewing in Beijing, Shanghai and Hong Kong in urban China in 2002. METHODS: Three hundred healthy urban Chinese women aged 20 to 49years were sampled by random telephone screening interviews. RESULTS: Examination of the factors associated with their responses to the telephone screening showed that the completion rates differed by day of the week and time of the day. The completion rates were higher onWednesday and Thursday than other weekdays, and higher on Sunday than Saturday at the weekend. There was a trend for the completion rates to peak from 18 :00 to 21:30 during weekday evenings and between 11:00 and 12:00 AM and 19:00 and 20:00 PM during weekends. There was no significant interviewer difference in the completion rates except for one interviewer in Hong Kong, indicating that interviewer performance did not influence completion rates. Of all numbers dialed, 25% of the responding persons refused, with almost all (94.3%) occurring at or near the beginning of the screening interviews, either before or at invitation. Key reasons for refusal included "hung up without any interaction" (35.1%), "not available to participate" (28.6%) or "not interested in survey" (19.0%). Most of the refusals were firm and not possible to reverse.

Adult↗
PubMed2005

[A cohort study on the relationship between nutrients intake and the incidence of hypertension in middle-aged Chinese].

OBJECTIVE: To explore the relationship between nutrient intake and the incidence of hypertension in middle-aged Chinese. METHODS: A prospective study was conducted in 653 men and women of Beijing and Guanzhou, aged 35-59 years. The subjects had no hypertension or other cardiovascular diseases at baseline risk factor and dietary survey carried out in 1983-1984. The baseline information of nutrient intake was collected by using a 24-hour recall method on three consecutive days. The incidence of hypertension was determined through the follow-up survey in 1993-1994. The subjects were categorized into three groups according to tritiles of each baseline nutrient intake and the relative risk for hypertension incidence in each group was calculated by using the logistic regression model with the group of lowest risk as the referent. RESULTS: During the period of 1983-1984 to 1993-1994, 170 among 653 subjects had developed hypertension; 92 were men and 78 were women. After adjustment for other risk factors, the relative risk of hypertension for different protein intake groups was 1.0, 0.87 (95% CI 0.54-1.40) and 0.52 (95% CI 0.32-0.87), respectively, and the p value for trend analysis was 0.011; the relative risk of hypertension for different sodium intake groups was 1.0, 1.12 (95% CI 0.66-1.88) and 1.85 (95% CI 1.09-3.14), respectively, and the p value for trend analysis was 0.015. There was no significant relationship between the other nutrient intake and hypertension incidence. CONCLUSION: Among middle-aged Chinese, protein and sodium may be two of the most important dietary factors affecting the incidence of hypertension. Increasing protein intake and reducing sodium intake might be helpful for the prevention of hypertension.

Adult↗
PubMed2005

[The plasma lipids level in adults among different areas in China].

OBJECTIVE: To study plasma total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C) levels of Chinese adults among different areas in China. METHODS: Analysis of fasting plasma lipid in 49,252 subjects aged 18 years and above was made. RESULTS: The mean TC, TG and HDL-C were 3.81 mmol/L, 1.10 mmol/L and 1.30 mmol/L, respectively. The mean TC, TG and HDL-C is 3.96 mmol/L, 1.16 mmol/L, 1.30 mmol/L in adults in urban and 3.75 mmol/L, 1.07 mmol/L and 1.30 mmol/L in adults in rural areas. In age groups of 18 - 44 years, 45 - 59 years and 60 years above, the mean values were 3.70 mmol/L, 4.09 mmol/L, 4.21 mmol/L for TC; 1.07 mmol/L, 1.21 mmol/L, 1.20 mmol/L for TG; and 1.29 mmol/L, 1.33 mmol/L, 1.33 mmol/L for HDL-C. CONCLUSION: The results of this study might provide the national representative data of plasma lipid level. TC and TG levels of adults in urban might be higher than those adults in rural. With increasing of age, the plasma TC level should be increased. There is no significant difference in TG levels between the adults aged 45-49 years and over 60 years, while the TG level of both age groups should be higher than those of adults aged 18-44 years.

Adult↗
PubMed2005

[Epidemiologic characteristics of dyslipidemia in people aged 18 years and over in China].

OBJECTIVE: To study the difference in prevalence of dyslipidemia, hypercholesterolemia, hypertriglyceridemia and low blood high-density lipoprotein cholesterol (HDL-C) between the residents of urban and rural areas of varied regions in China. METHODS: Fasting plasma levels of total cholesterol, triglyceride and HDL-C were determined with the enzyme methods for 49,252 subjects aged 18 and over during August to December, 2002. RESULTS: Prevalence of dyslipidemia in Chinese adults aged 18 and over was 18.6%, with 17.0%, 22.9% and 23.4% in the groups of 18-44, 45-59 and over 60 years old, respectively, 22.2% and 15.9% in males and females, respectively, and 21.0% and 17.7% in urban and rural areas, respectively. Prevalence of hypercholesterolemia, hypertriglyceridemia and low blood HDL-C in those aged 18 and over was 2.9%, 11.9% and 7.4%, respectively. CONCLUSIONS: Dyslipidemia has become one of important risk factors threatening health of Chinese people, with hypertriglyceridemia and low blood HDL-C as two major types in those aged 18 and over. Prevalence of dyslipidemia was nearly the same in the middle-aged and in the elderly people, and not significantly different in those living in urban areas from those in rural areas. It is very important to pay more attention to earlier comprehensive prevention and control of dyslipidemia.

Adult↗
PubMed2005

[The current status on the prevalence, awareness, treatment and control of diabetes mellitus in several Chinese subpopulations].

OBJECTIVE: To determine the prevalence of impaired fasting glucose (IFG), diabetes mellitus(DM), rates of awareness, treatment and control of DM in 14 Chinese subpopulations and the trends of development in recent years. METHODS: We collected data on history regarding DM and fasting serum glucose in 14 Chinese subpopulations aged 35 to 59 in 1998, under cluster sampling. In 4 out of the 14 subpopulation samples, a similar survey using same methods in 1993 - 1994 was carried out. IFG and DM were diagnosed according to the WHO criteria. RESULTS: The age-standardized prevalence rates of IFG and DM were from 0.5% to 15.6% (mean: 4.8%) and from 0.2% to 10.6% (mean: 4.3%) for the whole 14 subpopulations in 1998 which were not different between men and women, but higher in urban than in rural (P < 0.01), but increased with age (P < 0.01). The rates of awareness,treatment and control of DM were from 0% to 46.2% (mean: 33.3%), from 0% to 46.2% (mean: 27.2%), and from 0% to 15.4% (mean: 9.7%), which were significantly higher in women than in men (P < 0.01), higher in urban than in rural (P = 0.031), and higher in older participants (P < 0.05), but not much different in the levels of education. The rate of treatment in patients with awareness of DM and the rate of control in patients with treated DM were 81.6% and 35.6% respectively, which were not different between men and women, urban and rural or among different age groups. The mean prevalence of DM increased from 3.8% in 1993 - 1994 to 4.6% in 1998 (P = 0.037). The rates of awareness, treatment and control of DM had an increasing trends but with no significant differences between years 1993 - 1994 and 1998. CONCLUSION: The prevalence of DM in 14 Chinese subpopulations exhibited no differences between men and women, but showing significant differences among areas and an increasing trend in the recent years. The rates of awareness, treatment, and control were still relatively low. To improve the efficacy of screening program and treatment seemed to be the two key issues in prevention and control of DM in China.

Adult↗
PubMed2005

[The development and Assessment on the general quality of life intrument for Chinese people].

OBJECTIVE: To develop a general quality of life (QOL) instrument for Chinese in accordance with the Chinese culture and to assess its reliability, validity and sensitivity. METHODS: A 35-item QOL questionnaire(QOL-35) was developed with reference to the World Health Organization QOL questionnaire(WHO-100) and the 36-item medical outcomes study on short-form health status(SF-36). Thirty five items were divided into six domains (general, physical, independent, psychological, social, environment) and one item on QOL transition. The reliability of QOL-35 was assessed by a test-retest survey among 127 adults with an interval of 24-72 hours. The internal consistency and validity were evaluated by a survey on 135 adults from outpatients or general population, using QOL-35, WHO-100 and SF-36. The adaptability was assessed by application to 1356 community-based samples in Beijing. RESULTS: (1)Test-retest reliability of QOL-35: weighted Kappa indexes for items were from 0.86 to 1.00. Intraclass correlation coefficients were from 0.68 to 0.94 for domains, and 0.94 for total score. (2) On internal consistency: Cronbach's Alphas were 0.93, 0.97 and 0.89 for QO1-35, WHO-100 and SF-36. (3)On construct validity. The accumulated proportions of variances of the preceding seven factors were 66.5%, 50.3% and 65.3% for QOL-35, WHO-100 and SF-36. (4) On criterion validity. Spearman correlation coefficients of total QOL score of QOL-35 with those of WHO-100 and SF-36 were 0.805 and 0.745. (5)The rates of chronic diseases were 53.1%, 33.1%, 26.4% and 25.1% from first to fourth quantile of the total QOL scores of QOL-35(P<0.05). (6)Cronbach's Alpha was from 0.68 to 0.93 in 135 subjects, and from 0.71 to 0.91 in 1356 individuals of natural population. CONCLUSION: The QOL-35 instrument satisfied test-retest reliability and was highly correlated with WHO-100 and SF-36, having fewer items but better construction validity, better internal consistency, and better discrimination ability. We suggested that QOL-35 be used as a replicable tool to assess quality of life in the Chinese general population.

Adult↗
PubMed2004

Reduction of excess sludge production by 3,3',4', 5-tetrachlorosalicylanilide in an activated sludge process.

The potential of 3,3',4',5-tetrachlorosalicylanilide (TCS) addition to an activated sludge continuous process to reduce excess sludge production by disrupting coupling between anabolism and catabolism was investigated. TCS was chosen as a metabolic uncoupler for continuous test in a lab-scale completely mixed activated sludge process. TCS reduced sludge yield by approximately 30% at a dosage of 40 mg/day. Substrate removal capability was not adversely affected by the presence of TCS, but effluent nitrogen concentration increased during the 60-day continuous operation. Sludge settleability of treated and control samples was qualitatively comparable and not significantly different. Microbial activities in terms of specific oxygen uptake rate were also enhanced, and the microbial population was altered. The results suggest that TCS is an effective chemical uncoupler that reduces sludge yield; process performance was not significantly affected by introduction of the uncoupler.

Adenosine Triphosphate↗
PubMed2004

Inhibiting uterine PC6 blocks embryo implantation: an obligatory role for a proprotein convertase in fertility.

Successful embryo implantation involves complex interactions between the embryo and the uterus and is critical in establishing pregnancy. Proprotein convertase (PC) 6 (PC6) is one of the PC endoproteases regulating protein function through posttranslational activation of precursor proteins, including growth and differentiation factors. Here we show that PC6 protein is induced in the uterine stromal cells specifically at the site of embryo attachment during early pregnancy in mice. In vivo blocking of uterine production of PC6 protein using morpholino antisense oligonucleotides in mice resulted in total inhibition of implantation, revealing a vital role for PC6 in modulating the uterus for embryo implantation. Studies in primates (rhesus monkey and human) showed a dramatic upregulation of endometrial PC6 during the phase of uterine receptivity and at implantation, particularly during a critical uterine cell differentiation process termed decidualization. Thus, the current studies have demonstrated that PC6 is an essential molecule in modulating uterine function to support the establishment of embryo implantation. Interestingly, PC6 is one of the PCs identified to be important in processing the coat protein of HIV; inhibition of PCs has been suggested to be an effective approach to reduce HIV transmission. We therefore propose the novel concept that PC6 could be a potential nonhormonal target in the female reproductive tract for dual protection for women, both in preventing pregnancy and reducing HIV infection.

Animals↗
PubMed2004

Binding of the bioactive component jatrorrhizine to human serum albumin.

The interaction between Jatrorrhizine with human serum albumin (HSA) were studied by fluorescence quenching technique, circular dichroism (CD) spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy. Fluorescence data revealed the presence of a single class of binding site on HSA and its binding constants (K) are 7.278 x 10(4), 6.526 x 10(4), and 5.965 x 10(4) L.mol(-1) at 296, 303, and 310 K, respectively. The CD spectra and FT-IR spectra have proved that the protein secondary structure changed in the presence of Jatrorrhizine in aqueous solution. The effect of common ions on the binding constants was also investigated. In addition, the thermodynamic functions standard enthalpy (DeltaH(0)) and standard entropy (DeltaS(0)) for the reaction were calculated to be -10.891 kJ.mol(-1) and 56.267 J.mol(-1) K(-1), according to the van't Hoff equation. These data indicated that hydrophobic and electrostatic interactions played a major role in the binding of Jatrorrhizine to HSA. Furthermore, the displacement experiments indicated that Jatrorrhizine could bind to the site I of HSA, which was also in agreement with the result of the molecular modeling study.

Berberine↗
PubMed2004

Differential gene expression in neural stem cells and oligodendrocyte precursor cells: a cDNA microarray analysis.

The use of neural stem cells (NSCs) or their progeny oligodendrocyte precursor cells (OPCs) represents a promising repair strategy for many neurological disorders. However, the molecular events and biological features during the transition from NSCs to OPCs remain unclear. In the present study, we isolated NSCs from the embryonic rat forebrain and induced them into OPCs by using B104 conditioned medium (B104CM) in vitro. We then employed cDNA array technology to compare changes in gene expression between the two cell populations. Among 1,176 genes examined, 40 were differentially expressed, and some of them may be involved in OPC differentiation from NSCs. Our findings thus provide new insights into the molecular basis of differentiation of OPCs from NSCs.

Animals↗
PubMed2004

Neuronal gene transfer by baculovirus-derived vectors accommodating a neurone-specific promoter.

Recombinant baculoviruses have been employed as gene delivery vectors for mammalian cells, including neurones, during recent years. The aim of the current study was to develop a new recombinant baculovirus vector capable of enhancing gene expression in neurones. A hybrid promoter constructed by fusing the enhancer of human cytomegalovirus (CMV) immediately early promoter to the human platelet-derived growth factor (PDGF) beta-chain promoter was placed into a baculovirus expression cassette. In cultured neurones, baculovirus vectors containing the hybrid promoter augmented transgene expression up to 100-fold greater than that mediated by titre-matched baculovirus vectors with the PDGF promoter alone. Double immunostaining of tissue sections collected from the striatum and the retina injected with the new baculovirus vector demonstrated its specificity in driving gene expression almost exclusively in neurones, confirming the feasibility of using a tissue-specific promoter in the context of baculovirus vectors to provide cell type-specific transgene expression. The attributes of the new baculovirus vector might have practical implications for gene therapy in the nervous system.

Adult↗
PubMed2004

Characteristic of structures and pi-hydrogen bond of dimers C2H4-nFn-HF (n=0,1,2).

By the counterpoise-correlated potential energy surface method (interaction energy optimization), five structures of the C(2)H(4-n)F(n)-HF (n = 0,1,2) dimers with all real frequencies have been obtained at MP2/aug-cc-pVDZ level. The influence of F substituent effect on the structure and pi-hydrogen bond of dimer has been discussed. For C(2)H(4-n)F(n)-HF (n = 1,2), the pi-hydrogen bonds are elongated comparing with that for C(2)H(4)-HF. For C(2)H(3)F-HF, g-C(2)H(2)F(2)-HF, cis-C(2)H(2)F(2)-HF, the pi-hydrogen bonds are further deformed. These changes (elongate, shift, and deformation) of pi-hydrogen bond mainly come from deformation of pi-electron cloud of C=C bond. The pi-electron cloud is pushed towards the one C atom, the pi H-bond shift also to the C direction. Since the two lobes of pi-electron cloud have deviated slightly from the molecular vertical plane passing through C=C bond, the pi-hydrogen bond is sloped. Intermolecular interaction energies of the dimers are calculated to be -3.9 for C(2)H(4)-HF, -2.8 for C(2)H(3)F-HF, -2.1 for g-C(2)H(2)F(2)-HF, -1.6 for cis-C(2)H(2)F(2)-HF, -1.3 kcal/mol for trans-C(2)H(2)F(2)-HF, at CCSD(T)/aug-cc-pVDZ level.

Journal Article↗
PubMed2004

Crystal structures of 2-acetylaminofluorene and 2-aminofluorene in complex with T7 DNA polymerase reveal mechanisms of mutagenesis.

The carcinogen 2-acetylaminofluorene forms two major DNA adducts: N-(2'-deoxyguanosin-8-yl)-2-acetylaminofluorene (dG-AAF) and its deacetylated derivative, N-(2'-deoxyguanosin-8-yl)-2-aminofluorene (dG-AF). Although the dG-AAF and dG-AF adducts are distinguished only by the presence or absence of an acetyl group, they have profoundly different effects on DNA replication. dG-AAF poses a strong block to DNA synthesis and primarily induces frameshift mutations in bacteria, resulting in the loss of one or two nucleotides during replication past the lesion. dG-AF is less toxic and more easily bypassed by DNA polymerases, albeit with an increased frequency of misincorporation opposite the lesion, primarily resulting in G --> T transversions. We present three crystal structures of bacteriophage T7 DNA polymerase replication complexes, one with dG-AAF in the templating position and two others with dG-AF in the templating position. Our crystallographic data suggest why a dG-AAF adduct blocks replication more strongly than does a dG-AF adduct and provide a possible explanation for frameshift mutagenesis during replication bypass of a dG-AAF adduct. The dG-AAF nucleoside adopts a syn conformation that facilitates the intercalation of its fluorene ring into a hydrophobic pocket on the surface of the fingers subdomain and locks the fingers in an open, inactive conformation. In contrast, the dG-AF base at the templating position is not well defined by the electron density, consistent with weak binding to the polymerase and a possible interchange of this adduct between the syn and anti conformations.

2-Acetylaminofluorene↗