Biomedical subjects

L-H Li

Publications and source records attributed to L-H Li.

3 recordsLinked to original sources

PubMed2006

A genome-wide study of preferential amplification/hybridization in microarray-based pooled DNA experiments.

Microarray-based pooled DNA methods overcome the cost bottleneck of simultaneously genotyping more than 100 000 markers for numerous study individuals. The success of such methods relies on the proper adjustment of preferential amplification/hybridization to ensure accurate and reliable allele frequency estimation. We performed a hybridization-based genome-wide single nucleotide polymorphisms (SNPs) genotyping analysis to dissect preferential amplification/hybridization. The majority of SNPs had less than 2-fold signal amplification or suppression, and the lognormal distributions adequately modeled preferential amplification/hybridization across the human genome. Comparative analyses suggested that the distributions of preferential amplification/hybridization differed among genotypes and the GC content. Patterns among different ethnic populations were similar; nevertheless, there were striking differences for a small proportion of SNPs, and a slight ethnic heterogeneity was observed. To fulfill appropriate and gratuitous adjustments, databases of preferential amplification/hybridization for African Americans, Caucasians and Asians were constructed based on the Affymetrix GeneChip Human Mapping 100 K Set. The robustness of allele frequency estimation using this database was validated by a pooled DNA experiment. This study provides a genome-wide investigation of preferential amplification/hybridization and suggests guidance for the reliable use of the database. Our results constitute an objective foundation for theoretical development of preferential amplification/hybridization and provide important information for future pooled DNA analyses.

Databases, Nucleic Acid↗

PubMed2006

Blood pressure and urinary sodium excretion in relation to the A-1984G adrenomedullin polymorphism in a Chinese population.

Adrenomedullin (ADM) is a vasodilator and inhibits salt appetite. An A-to-G substitution at position -1984 in the promoter region of the ADM gene likely increases transcription. We therefore investigated this polymorphism in relation to blood pressure and urinary sodium in a Chinese population. We genotyped 427 Chinese enrolled in a family-based population study. We measured blood pressure by conventional sphygmomanometry and ambulatory monitoring. The frequencies of the ADM AA, AG, and GG genotypes were 50.6, 38.2, and 11.2%, respectively. In adjusted analyses, G allele carriers, compared to AA homozygotes, had significantly lower conventional (45.3 versus 48.5 mm Hg, P = 0.004) and 24-h (42.6 versus 44.3 mm Hg, P = 0.03) pulse pressures and urinary sodium excretion (143.8 versus 159.4 mmol/day, P = 0.03). In parents, but not offspring, both systolic pressure and pulse pressure were significantly (P<0.01) lower in G allele carriers. The genotypic difference in sodium excretion was consistent across the age range. In 68 informative offspring, transmission of the G allele was associated with lower urinary sodium excretion (effect size, 40.1 mmol/day, P = 0.01). In 81 healthy volunteers, the plasma ADM concentration was 15.2% higher in GG homozygotes than in sex- and age-matched AA subjects (11.4 versus 9.9 pmol/l, P = 0.10). In conclusion, in Chinese, the ADM -1984G allele is associated with lower sodium excretion and in older subjects also with lower systolic pressure and narrower pulse pressure.

Adrenomedullin↗

PubMed2005

Aetiology of sexually transmitted disease (STD) and comparison of STD syndromes and aetiological diagnosis in Taipei, Taiwan.

Between July 2002 and July 2004, all male patients (n=307) presenting to a sexually transmitted disease (STD) clinic who reported unprotected sex were enrolled in the study. Of these, 63 (20.5%), 19 (6.2%) and one (0.3%) were infected with one, two and three pathogens, respectively. The prevalences of chlamydial infection, gonorrhoea, syphilis, human immunodeficiency virus infection and trichomoniasis were 14.3%, 10.1%, 6.8%, 2.2% and 0%, respectively. The sensitivities of urethral discharge syndrome for detection of chlamydial, gonococcal, and combined forms of infection were 31.8%, 58.5% and 70.0%, respectively, with specificities of 93.5%, 97.1% and 93.9%, respectively. Positive predictive values (PPVs) were 56.0%, 68.0% and 28.0% for chlamydial and gonococcal infections and combinations of the two forms, respectively. In contrast, the sensitivity of genital ulceration syndrome for syphilis detection was only 38.0%, although the specificity was 82.5%, and the PPV was 32.0%. To reduce the number of false-positive results for STD patients who practise unprotected sex, incorporation of risk assessment and rapid diagnostic tests are recommended.

Adult↗