Biomedical subjects

Xiao-Guang Yang

Publications and source records attributed to Xiao-Guang Yang.

13 recordsLinked to original sources

PubMed2006

Using amino acid and peptide composition to predict membrane protein types.

Membrane proteins play an important role in many biological processes and are attractive drug targets. Determination of membrane protein structures or topologies by experimental methods is expensive and time consuming. Effective computational method in predicting the membrane protein types can provide useful information for large amount of protein sequences emerging in the post-genomic era. Although numerous algorithms have addressed this issue, the methods of extracting efficient protein sequence information are very limit. In this study, we provide a method of extracting high order sequence information with the stepwise discriminant analysis. Some important amino acids and peptides that are distinct for different types of the membrane proteins have been identified and their occurrence frequencies in membrane proteins can be used to predict the types of the membrane proteins. Consequently, an accuracy of 86.5% in the cross-validation test, and 99.8% in the resubstitution test has been achieved for a non-redundant dataset, which includes type-I, type-II, multipass transmembrane proteins, lipid chain-anchored and GPI-anchored membrane proteins. The fingerprint features of the identified peptides in each membrane protein type are also discussed.

Amino Acid Sequence↗

PubMed2006

[Study on the development of DNA immunization technique].

As the third generation of vaccine, DNA immunization seems to be advantageous over classic immunization with purified proteins, which can induce complete immune responses against a number of infectious agents and can be used safely, economically and conveniently. The author reviews the new development of DNA immunization, including parameters affecting its effectiveness, the basic underlying biological mechanisms, and its application on generation of antibodies, infant immunization, mucous membrane immunization, and expression library immunization etc. In addition, we introduce some strategies of improving the effect of DNA immunization.

Animals↗

PubMed2006

Report on childhood obesity in China (2). Verification of BMI classification reference for overweight and obesity in Chinese children and adolescents.

OBJECTIVE: To verify Working Group for Obesity in China (WGOC) recommended body mass index (BMI) classification reference for overweight and obesity in Chinese children and adolescents using the data of 2002 China Nationwide Nutrition and Health Survey. METHODS: Pediatric metabolic syndrome (MetS) and abnormality of each risk factor for MetS were defined using the criteria for US adolescents. Definition of hyper-TC, LDL, and dyslipidemia in adults was applied as well. The average level and abnormality rate of the metabolic indicators were described by BMI percentiles and compared with general linear model analysis. Receiver operating characteristic analysis was used to summarize the potential of BMI to discriminate between the presence and absence of the abnormality of these indicators. RESULTS: There was neither significantly increasing nor significantly decreasing trend of biochemical parameter levels in low BMI percentile range (<65th). Slight increasing trend from the 75th and a significant increase were found when BMI > or =85th percentile. In general, the prevalence of the examined risk factors varied slightly when BMI percentile<75th, and substantial increases were consistently seen when BMI percentile > or =75th. As an indicator of hyper-TG, hypertension and MetS, the sensitivity and specificity were equal at the point of BMI<75th percentile, and the Youden's index of risk factors also reached peak point before 75th percentile except for MetS. When the BMI percentile was used as the screening indicator of MetS, Youden's index reached peak point at 85th percentile, just the point in the ROC graph that was nearest to the upper left corner. CONCLUSION: The BMI classification reference for overweight and obesity recommended by WGOC is rational to predict and prevent health risks in Chinese children and adolescents. Lower screening cut-off points, such as 83th percentile or 80th percentile, should not be excluded when they are considered as overweight criteria in future intervention or prevention studies.

Adolescent↗

PubMed2005

Studies on BN rats model to determine the potential allergenicity of proteins from genetically modified foods.

AIM: To develop a Brown Norway (BN) rat model to determine the potential allergenicity of novel proteins in genetically modified food. METHODS: The allergenicity of different proteins were compared, including ovalbumin (OVA), a potent respiratory and food allergen, bovine serum albumin (BSA), a protein that is considered to have a lesser allergenic potential, and potato acid phosphatase (PAP), a non-allergenic protein when administered to BN rats via different routes of exposure (intraperitoneally or by gavage). IgG and IgE antibody responses were determined by ELISA and PCA, respectively. An immunoassay kit was used to determine the plasma histamine level. In addition, possible systemic effect of allergens was investigated by monitoring blood pressure. RESULTS: OVA provoked very vigorous protein-specific IgG and IgE responses, low grade protein-specific IgG and IgE responses were elicited by BSA, while by neither route did PAP elicit anything. In either routes of exposure, plasma histamine level in BN rats sensitized with OVA was higher than that of BSA or PAP. In addition, an oral challenge with BSA and PAP did not induce any effect on blood pressure, while a temporary drop in systolic blood pressure in few animals of each routes of exposure was found by an oral challenge with OVA. CONCLUSION: BN rat model might be a useful and predictive animal model to study the potential allergenicity of novel food proteins.

Acid Phosphatase↗

PubMed2005

[Study on the food safety of the marker gene expressed protein HPT].

OBJECTIVE: This article studied on the food safety of HPT protein (Hygromycin B Phosphotransferase), a kind of plant selectable marker gene expression product, which mainly included the quantity and quality detection of HPT in the SCK transgenic rice plants, the possible dietary intakes and its stability in the simulative digestive system. METHODS: HPT cDNA fragment was inserted into the prokaryotic expressing vector pBV222 for the expression of 6His-HPT fusion protein. The inclusion bodies were denatured by 8 mol/L urea and purifiee with metal chelate affinity chromatography on Ni-NTA agarose under denaturing condition. The purified 6His-HPT were used to immunize rabbit and BALB/C mice for the preparation of the polyclonal and monoclonal antibodies, and the double-Ab sandwich ELISA to detect HPT was established then. Concerning the sensitivity assessment of HPT protein, the amino acid sequences of HPT was compared with the other allergens and the simulative digestive experiment in vitro was carried out too. RESULTS: 6His-HPT protein was obtained with the purity up to 95%. The specificity of antisera and ascites was detected by Western blot, which showed specific binding reaction between the antibodies to the purified 6His-HPT proteins and their expressed product. The double-Ab sandwich ELISA system was established successfully with the sensitivity of 30 ng/ml. The HPT expression level in the leaves of transgenic rice was proved in the range of 80 - 150 ng/ml, yet we cannot detect HPT protein in the seeds of the same rice. There showed no comparability in the amino acid sequences between HPT and other allergens, and HPT protein was digested quickly in the simulated stomach and intestines liquids. CONCLUSION: All the results showed that the expression level of HPT in the SCK transgenic rice plants is very low and they are not stable in the simulative digestive system. So we inferred that under the current detection level, HPT protein might not be able to induce any safety problem. Yet further study on the acute toxicity and sensitivity experiments by the animals need to be carried out, and the results will be reported in the near future.

Animals↗

PubMed2005

[Effect of anthocyanin rich fruit extract on PGE2 produced by endothelial cells].

OBJECTIVE: To study the effect of anthocyanin rich fruit extract on PGE2 produced by endothelial cells. METHODS: Normal human endothelial cells, CRL-2606, were cultured in F12K medium (complemented with 10% FBS, 0.1 mg/ml heparin, 0.03 mg/ml ECGS, 50 microg/ml streptomycin and 500U/ml penicillin) in 5% CO2 with 95% air at 37 degrees C. When the cells grow close to confluence, anthocyanin rich fruit extract with/without 100 ng/ml of LPS were added to the medium. After 18 hours of incubation, cells were harvested and the supernatant were collected. Cell viability was assayed. After centrifugation, PGE2 concentration in the supernatant was measured with the STAT-Prostaglandin E2 EIA Kit. RESULTS: 300 microg/ml or higher Chokeberry extract showed cytotoxicity effect on CRL-2606 cells, the viability was lower than 60% and showed a dose-response manner. Under using dosage, Blackcurrant extract (100 - 700 microg/ml) and Blueberry extract (50 - 400 microg/ml) did not show any cytotoxicity. When stimulated by LPS, the production of PGE2 by endothelial cells were increased two fold. Blueberry extract inhibit such action. 100 microg/ml of Blueberry extract keeps the production of PGE2 in normal level. 700 microg/mL of Blackcurrant extract and 500 microg/ml Chokeberry extract also inhibit the releasing of PGE2. CONCLUSION: Anthocyanin rich fruit extract from Blueberry, Blackcurrant, and Chokeberry inhibit PGE2 produced by endothelial cells, there exist antiinflammation and antioxidation.

Anthocyanins↗

PubMed2005

[Distribution of feeding index and association between feeding index and growth of infants and young child aged 6 - 24 months].

OBJECTIVE: Data from the Nutrition and Health Survey of the Chinese People on 2002 were use to explore the feasibility of creating a composite feeding index and examine the association between feeding practices and growth of infants and young child. METHODS: The variables used for index were as follows: current breast-feeding, introduction of complementary foods, the past month and feeding frequency. The index was made age specific for 6- to 9-, 9- to 12- and 12- to 24-month-old age groups, age-specific feeding terciles were created to evaluate the association between feeding index and growth. RESULTS: the socres of feeding practice were different significantly between urban and rural. Bivariate analyses showed that feeding practices were strongly and significantly associated with child growth in China, especially with increasing age, the scores of feeding practices were increasing. CONCLUSION: The present study showed that better feeding practices were more important for children of lower socioeconomic status, The data available in CNHS data can be used effectively to create a composite child feeding index which could be targeted by nutrition education and behavior change interventions.

Body Height↗

PubMed2005

Preparation of monoclonal antibody against HPT and its application to detecting marker protein in genetically modified rice.

OBJECTIVE: To produce the monoclonal antibodies (mAbs) against hygromycin B phosphotransferase (HPT) and to develop immunoassay based on mAbs for biosafety assessment of HPT in genetically modified rice (GM rice). METHODS: BALB/c mice were immunized with purified recombinant 6His. HPT protein, and the conventional hybridoma technology was used to generate the monoclonal hybridoma cells. ELISA and Western blot were used to analyze the specificity of mAbs recognizing HPT and the cross reaction with other proteins. A double-Ab sandwich ELISA method was established to detect HPT expression level in the sck gene-modified rice plants. RESULTS: Four hybridomas, named F1, D4-2, D4-4, and D4-5, producing the mAbs against HPT were successfully obtained with the titer of ascetic mAbs ranging from 1x10(-4) to 1x10(-5). Identification of subclass showed that all the produced mAbs belonged to IgG1. Western blot showed specific binding reaction between the mAbs to the HPT proteins expressed in the GM rice. A double sandwich ELISA coated with anti-HPT polyclonal antibody was established with mAbs as sandwich antibody, which showed a sensitivity of 30ng/mL and did not crossreact with other proteins. The expression level of HPT in the leaves of sck-transformed lines was detected (80-150ng/mL). But HPT protein in the grain and seed of GM rice could not be detected using this ELISA assay. CONCLUSION: Anti-HPT mAbs prepared herein have a high specificity and can be used for rapid assay of HPT antigen. The expression level of HPT in the GM rice grain and seed is lower than our ELISA detection limit.

Animals↗

PubMed2005

Disease risks of childhood obesity in China.

OBJECTIVE: To estimate the relative risks of dyslipidemia, hypertension, diabetes mellitus, and metabolic syndromes among overweight and obese Chinese children compared with their normal weight counterparts. METHODS: Overweight and obesity were defined by age- and sex-specific BMI classification reference for Chinese children and adolescents. Pediatric metabolic syndrome (MetS) and each risk factor for MetS were defined using the criteria for US adolescents. Definition of hyper-TC, LDL, and dyslipidemia for adults was applied as well. General linear model factor analysis and chi-square test were used to compare the difference in metabolic indicators among normal weight, overweight, and obese groups. Multiple logistic regression analysis was performed to estimate the odds ratio of metabolic abnormalities between obesity, overweight, and normal weight children, after adjustment for living area, family economic level, age, sex, and daily exercise time and TV watching time, as well as different dietary indices in the model. RESULTS: Significant increases in blood lipids, glucose, and blood pressure were found among overweight and obese children as compared with their counterparts with normal weight. By applying WGOC-recommended BMI classification, the risks for hypertriglyceridemia, low HDL and dyslipidemia among overweight children were 1.9, 1.4, and 1.5 times, and was 3.3, 1.5, and 1.8 times among obese groups compared to their counterparts with normal weight after adjustment for age, sex, region, socioeconomic status, physical activity, and dietary intakes. The overweight and obese children (15-17.9 years) had a high-risk of developing hypertension, which was 2.3 and 2.9 times higher than their counterparts with normal weight. Above 90% obese adolescents had abdominal obesity, while less than 1% normal weight ones had abdominal obesity. No obese adolescents were free from any risk factors for MetS, while 36.9% of normal weight adolescents were from the risk factors. 83.3% obese boys and all obese girls had metabolic syndrome, while only 15.5% normal weight boys and 18.8% normal weight girls had metabolic syndrome. Four risk factors for metabolic syndrome were found in 8.3% obese boys while none in normal weight boys and girls. The prevalence of MetS among normal weight, overweight, and obesity groups was 1.5%, 18.3%, and 38.1% respectively. CONCLUSION: The cardiovascular disease (CVD) risk factors are clustered in obese Chinese children. Our observations strongly suggest that efforts should be made to prevent the onset of overweight and its associated diseases during early childhood.

Adolescent↗

PubMed2003

Purification and immunity analysis of recombinant 6His-HPT protein expressed in E. coli.

OBJECTIVE: To obtain HPT protein (Hygromycin B Phosphotransferase), a kind of plant selective maker gene product expressed from E. coli and to prepare the polyclonal antibody (pAbs) against it. METHODS: HPT cDNA fragment was obtained by PCR and was inserted into the prokaryotic expressing vector pBV222. Then the constructed recombinant plasmid pBV222-HPT was transferred into E. coli DH5alpha for HPT expression. The recombinant expressing system was confirmed by restriction endonuclease digestion, DNA sequencing and protein expression. E. coli cells were lysed by sonication and detergent dissolution. After cell membrane was extracted, the inclusion bodies were denatured by 8 mol/L Urea and purified with metal chelate affinity chromatography on Ni-NTA agarose under denaturing condition. The purified 6His-HPT was characterized by SDS-PAGE, and used to immunize rabbit. The titer and specificity of antisera were detected by ELISA and Western blot respecitively. RESULTS: Analysis of DNA sequence and restricted enzymes showed that the sequence of PBV222-HPT plasmid was correct. The amount of recombinant HPT expressed in E. coli accounted for 30% of total cellular proteins. From 1 liter of fermentative bacteria about 22 milligrams of pure recombinant HPT was isolated with purity above 95%. The recombinant HPT protein could produce high titer antiserum in rabbits and show good immunity activity. Western blot showed specific binding reaction between the antiserum to the purified 6His-HPT protein and their expressed products (plants protein and bacterial protein). CONCLUSION: HPT protein can be expressed and purified from E. coli by a relatively simple method, which has high immunity activity.

DNA, Bacterial↗

PubMed2003

[Study on the preparing of polyclonal antibodies against plant-selected maker gene hpt expression protein by DNA immunization].

AIM: To prepare the polyclonal antibodies (pAbs) against HPT, a kind of plant-selected maker gene encoding protein, by DNA immunization technique and explore the influencing factors for this gene immunization. METHODS: The coding sequence of hpt was cloned into eukaryotic expression vector pCDNA3. The sequence of the plasmid pCDNA3-HPT was demonstrated by restricting enzyme digestion analysis and DNA sequencing. The sequence-correct recombinant plasmids were purified and used to immunize BALB/c mice. The titer and specificity of antisera were detected by ELISA and Western blot, respecitively. RESULTS: No pAb against HPT was detected following three immunization with hpt genes. Then mice were divided into three groups when the forth booster immunization was carried out: 1st group (immunization with the endotoxin-free recombinant plasmids), 2nd group (immunization with (His)(6)-HPT fusion protein expressed in E.coli) and 3rd group (immunization with the same plasmids as before mentioned). As a result, the pAb titer of the 1st group mice increased to 1:200, and the that of 2nd group was up to 1:2 000. Yet the 3rd group detected no anti-HPT antibody. Western blot analysis had proved that antisera of the first two groups could produce specific binding reaction to the purified GST-HPT, (His)(6)-HPT protein and their expressed product (bacterial protein). CONCLUSION: We have got successfully the specific pAb against HPT by DNA immunization, but its titer is yet unsatisfactory, inferring that the character of the hpt gene self and its expression level may play an important role. In order to raise level of serum antibody prepared by DNA immunization, the farther study on various influencing factors still need to be performed.

Animals↗

PubMed2003

[Fusion expression, purification and bioactivity assay of CpTI in Escherichia coli].

CpTI (Cowpea Trypsin Inhibitor) is a widely used insect resistance gene in the plant genetic engineering for its high insecticidal activity and the minimal ability of the insects to evolve resistance to it. To facilitate the safety assessment of genetically modified foods (GMFs) with CpTI protein, we need to produce gram quantities of this protein in microbes. With the pGEX fusion expression system, we expressed the GST-CpTI protein in E. coli BL21, which accounted for approximately 40% of germ proteins. By Glutathione Sephrose 4B affinity chromatography, GST-CpTI was obtained with the purity up to 90%. Overnight incubate the fusion proteins with Thrombin protease, we got the CpTI proteins cleavage of GST tag. Both of the GST-CpTI and CpTI proteins showed notable trypsin inhibitor activity. Immunization of rabbits with purified fusion protein generated high titer antibodies (> 20000), measuring by ELISA. Western Blotting also showed specific Ag-Ab binding band between the antiserum and the CpTI proteins no matter in the whole supersonic germ proteins or purified from the column. All these made a good ground for the further safety assessment of CpTI protein.

Animals↗

PubMed2002

Predicting membrane protein types using residue-pair models based on reduced similarity dataset.

An algorithm to predict the membrane protein types based on the multi-residue-pair effect in the Markov model is proposed. For a newly constructed dataset of 835 membrane proteins with very low sequence similarity, the overall prediction accuracy has been achieved as high as 81.1% and 71.7% in the resubstitution and jackknife test, respectively, for a prediction of type I single-pass, type II single-pass, multi-pass membrane proteins, lipid chain-anchored and GPI-anchored membrane proteins. The improvement of about 11% in the jackknife test can be achieved compared with the component-coupled algorithm merely based on the amino acid composition (AAC approach). The improvement is also confirmed on a high similarity dataset and the other extrapolating test. The result implies that designing more incisive analysis tools, one should develop algorithms based on the representative dataset with lower sequence similarity. The present algorithm is useful to expedite the determination of the types and functions of new membrane proteins and may be useful for the systematic analysis of functional genome data in a large scale. The computer program is available on request.

Algorithms↗