Biomedical subjects

Dongyan Yang

Publications and source records attributed to Dongyan Yang.

7 recordsLinked to original sources

PubMed2004

Applications of Bayesian statistical methods in microarray data analysis.

Microarray technology allows one to measure gene expression levels simultaneously on the whole-genome scale. The rapid progress generates both a great wealth of information and challenges in making inferences from such massive data sets. Bayesian statistical modeling offers an alternative approach to frequentist methodologies, and has several features that make these methods advantageous for the analysis of microarray data. These include the incorporation of prior information, flexible exploration of arbitrarily complex hypotheses, easy inclusion of nuisance parameters, and relatively well developed methods to handle missing data. Recent developments in Bayesian methodology generated a variety of techniques for the identification of differentially expressed genes, finding genes with similar expression profiles, and uncovering underlying gene regulatory networks. Bayesian methods will undoubtedly become more common in the future because of their great utility in microarray analysis.

Bayes Theorem↗

PubMed2004

[Safety assessment of GM yeast feed additive with cecropin CAD gene].

OBJECTIVE: To evaluate the safety of GM yeast feed additive with cecropin CAD and to study and set up a model of Safety assessment for GM feed and detecting method. METHODS: To ensure the safety of the GM products, it has been done that to detect and value the safety of receptor organisms and expression products of extrinsic gene, the genetic stability of biologic properties of genomic modified yeast feed and condition of transfer and cumulation of anti-bacterial peptide and its products in circumstance and the feeded animals. RESULT AND CONCLUSION: The receptor animals and expression products of extrinic gene are safe, and the genomic modified products have steady genetic characters. The cectopin CAD neither cumulates in feeded animal nor releases into environment. The genomic modified feed additive is safe.

Animal Feed↗

PubMed2003

Results of soy-based meal replacement formula on weight, anthropometry, serum lipids & blood pressure during a 40-week clinical weight loss trial.

BACKGROUND: To evaluate the intermediate-term health outcomes associated with a soy-based meal replacement, and to compare the weight loss efficacy of two distinct patterns of caloric restriction. METHODS: Ninety overweight/obese (28 < BMI < or = 41 kg/m2) adults received a single session of dietary counseling and were randomized to either 12 weeks at 1200 kcal/day, 16 weeks at 1500 kcal/d and 12 weeks at 1800 kcal/d (i.e., the 12/15/18 diet group), or 28 weeks at 1500 kcal/d and 12 weeks at 1800 kcal/d (i.e., the 15/18 diet group). Weight, body fat, waist circumference, blood pressure and serum lipid concentrations were measured at 4-week intervals throughout the 40-week trial. RESULTS: Subjects in both treatments showed statistically significant improvements in outcomes. A regression model for weight change suggests that subjects with larger baseline weights tended to lose more weight and subjects in the 12/15/18 group tended to experience, on average, an additional 0.9 kg of weight loss compared with subjects in the 15/18 group. CONCLUSION: Both treatments using the soy-based meal replacement program were associated with significant and comparable weight loss and improvements on selected health variables.

Clinical Trial↗

PubMed2003

[Progress on cerebral toxicity of arsenic].

It has been demonstrated in epidemiological studies in recent years that people exposed to chronic arsenic with high doses for a long time may lead to peripheral nervous symptoms. This paper reviewed the toxicity of arsenic on brain and the effects of superior nerve activities on central nervous system as well as the progress of its related mechanism.

Animals↗

PubMed2003

[Effect of arsenic toxicity on morphology and viability of enzyme in primary culture of rat hippocampal neurons].

In order to study the toxic consequences of arsenic at different levels on hippocampal neurons of rat, different doses of sodium arsenite (0, 0.08, 0.40, 2.00 and 10.00 mg/L) were given to observe the changes of viability, morphological and biochemical parameters. The results showed that the arsenite content in primarily cultured rat hippocampal neurons decreased in growth of viable cells. The morphometric analysis showed that the isolated neonatal hippocampal neurons exposed to lower concentration of arsenic had cytoplasm vacuoles, frothing and nuclear condensation with the intact membrane, indicating the possible induction of apoptosis, whereas higher dose of arsenic leaded to the appearance of necrosis. The degeneration of cytoplasm with the appearance of large vacuoles and loss of cell-cell junction were also observed. Meanwhile the Nissles decreased in the cytoplasm confirmed by the Tolidine blue. Biochemically determined increase in the viability of L-LDH showed increased in extra-cellular release as well as decrease in AchE. Some results showed the dose-time dependent relationship. It is suggested that the neonatal hippocampal neurons of rat treated with different doses of arsenic suffered from morphological changes including degeneration, apoptosis and necrosis in various degrees.

Acetylcholinesterase↗

PubMedDate not supplied

The confounding of race and geography: how much of the excess stroke mortality among African Americans is explained by geography?

INTRODUCTION: The excess stroke mortality among African Americans and Southerners is well known. Because a higher proportion of the population living in the 'Stroke Belt' is African American, then a portion of the estimated excess risk of stroke death traditionally associated with African-American race may be attributable to geography (i.e., race and geography are 'confounded'). In this paper we estimate the proportion of the excess stroke mortality among African Americans that is attributable to geography. METHODS: The numbers of stroke deaths at the county level are available from the vital statistics system of the US. A total of 1,143 counties with a population of at least 500 whites and 500 African Americans were selected for these analyses. The black-to-white stroke mortality ratio was estimated with and without adjustment for county of residence for those aged 45-64 and for those aged 65 and over. The difference in the stroke mortality ratio before versus after adjustment for county provides an estimate of the proportion of the excess stroke mortality inappropriately attributed to race (that is in fact attributable to geographic region). RESULTS: For ages 45-64, the black-to-white stroke mortality ratio was reduced from 3.41 to 3.04 for men, and from 2.82 to 2.60 for women, suggesting that between 10 and 15% of the excess mortality traditionally attributed to race is rather due to geography. Over the age of 65, the black-to-white stroke mortality ratio was reduced from 1.31 to 1.27 for men, and from 1.097 to 1.095 for women, suggesting that between 2 and 13% of the excess mortality attributed to black race is actually attributable to geography. The reductions of all the four age strata gender groups were highly significant. DISCUSSION: These results suggest that a significant, although relatively small, proportion of the excess mortality traditionally attributed to race is rather a factor of geography.

Age Factors↗

PubMedDate not supplied

Joint tests for quantitative trait loci in experimental crosses.

Selective genotyping is common because it can increase the expected correlation between QTL genotype and phenotype and thus increase the statistical power of linkage tests (i.e., regression-based tests). Linkage can also be tested by assessing whether the marginal genotypic distribution conforms to its expectation, a marginal-based test. We developed a class of joint tests that, by constraining intercepts in regression-based analyses, capitalize on the information available in both regression-based and marginal-based tests. We simulated data corresponding to the null hypothesis of no QTL effect and the alternative of some QTL effect at the locus for a backcross and an F2 intercross between inbred strains. Regression-based and marginal-based tests were compared to corresponding joint tests. We studied the effects of random sampling, selective sampling from a single tail of the phenotypic distribution, and selective sampling from both tails of the phenotypic distribution. Joint tests were nearly as powerful as all competing alternatives for random sampling and two-tailed selection under both backcross and F2 intercross situations. Joint tests were generally more powerful for one-tailed selection under both backcross and F2 intercross situations. However, joint tests cannot be recommended for one-tailed selective genotyping if segregation distortion is suspected.

Computer Simulation↗