Biomedical subjects

Peng-cheng Xun

Publications and source records attributed to Peng-cheng Xun.

4 recordsLinked to original sources

PubMed2006

[Estimation on gene-environment interaction in the partial case-control study].

OBJECTIVE: To introduce the approaches for estimating gene-environment interaction based on partial case-control studies. METHODS: The effects of logistic model and log-linear model for estimating the main effects and gene-environment interaction effect were estimated by means of maximum likelihood methods in traditional case-control studies, case-only studies and partial case-control studies, respectively. An example was also illustrated. RESULTS: In traditional case-control study with complete data, the results of logistic model and log-linear model were equivalent. In case-only study without any information about controls, the logistic model can also efficiently estimate gene-environment interaction. In partial case-control study, environmental information was collected from all of the cases and controls, while genetic information was only collected from cases. For this case-control study with incomplete data, a suitable parameterized log-linear model could simultaneously and efficiently estimate the main effect of environment and gene-environment interaction, whereas the logistic model could not. CONCLUSION: For a partial case-control study, log-linear model could estimate not only the main effect of environment but also gene-environment interaction. If genotype and exposure were independent, estimators from partial case-control were as precisely as those from complete-data case-control studies.

Case-Control Studies↗

PubMed2006

[A cross-sectional survey of blindness and low vision among adults aged 60 years and above in Xinchengqiao Blocks, Nantong].

OBJECTIVE: To investigate the prevalence and causes of blindness and low vision among adults aged > or = 60 years in the urban population of Nantong. METHODS: Cluster sampling was used to select 8 from 14 communities in Xinchengqiao Blocks, in which all individuals aged > or = 60 years were visited. The visual acuity without correction and the presenting acuity with the participants' habitual distance correction were measured separately for each eye. In individuals with visual acuity less than 0.6, pinhole visual acuity was tested with pinhole spectacle. External eye, anterior segment and ocular fundus were examined by the ophthalmologist using a slit lamp-microscope and direct ophthalmoscopy. The survey was preceded by a pilot study. RESULTS: Of 3352 enumerated subjects, 3040 individuals participated in this survey (90.69% response rate). According to pinhole visual acuity and World Health Organization (WHO) visual impairment criterion (blindness: less than 0.05 in the better eye; low vision: less than 0.3 to 0.05 in the better eye), the prevalence of blindness and low vision was 1.35% and 1.84% respectively. The prevalence of blindness and low vision for females were 1.92% and 2.33%, respectively, which were differenced from that in males (0.66% and 1.24%, respectively). The prevalence of blindness and low vision increased with age. The survey showed that the most important cause leading to blindness and low vision was cataract. According to the presenting visual acuity and visual impairment criterion (blindness: less than 0.1 in both eyes), the prevalence of blindness and visual impairment was 1.58% and 13.59%, respectively, 2.10% and 15.98% in females and 0.95% and 10.66% in males, respectively. The prevalence of blindness and visual impairment was raised with increasing age. Cataract was also the leading cause for blindness. CONCLUSIONS: The prevalence of blindness in the Nantong area was lower than that in northern, southern and western China. Females and illiteracy were more likely to have blindness and low vision than that of males and literate. The leading causes of blindness in Nantong are, in descending sequence, cataract, ocular fundus diseases, ametropia and corneal scar/opacity.

Aged↗

PubMed2005

[Effects of three madriatics on the human ocular aberrations].

OBJECTIVE: To evaluate the effects of three common madriatics-phenylephrine, tropicamide and Mydrin-P on aberrations in human eye. METHODS: General aberrations, lower- and higher-order aberrations (HOA) were measured at the pupil diameter 4.0 mm and 7.0 mm with Allegretto Wave Analyzer on 37 eyes of 19 young volunteers whose spherical equivalence (SE) ranged from -0.25 D to -6.00 D. Four measured conditions were used for each subject. (1) Topical installation of 3 drops 5.0% phenylephrine hydrochloride. (2) Topical installation of 3 drops 0.5% tropicamide. (3) Topical installation of 3 drops Mydrin-P. (4) Topical installation of 3 drops 0.3% Tarivid, prior to aberometry measurements. The differences were analyzed on the values of the root-mean-square (RMS) of general (RMSg) and higher-order aberrations (RMSh), coefficient of defocus, astigmatism, the third aberrations, primary spherical aberration and the dominating type of HOA among three madriatics or between the madriatics and Tarivid solution respectively. RESULTS: There was no significant difference among the three madriatics in the average value of RMSg, RMSh, C3-C9 and C12 (P > 0.05). However, small but statistically significant difference was found in the disparity between any madriatic and Tarivid at the condition of 4.0 mm diameter of pupil. The disparity of 5% phenylephrine over RMSg and C4 was the smallest, and showed significant difference (P < 0.05). The third order aberration was more frequent dominating type of HOA over a 4.0 mm and 7.0 mm pupil for 4 eye drops, and C7 was the most frequent one among all the volunteers; there were 28 eyes (75.7%), 20 eyes (54.1%) which dominating type of HOA changed. CONCLUSIONS: All the three madriatics can be used to measure the higher-order aberrations, spherical aberration and coma in the young myopic persons. However, phenylephrine measurement may be the choice for lower-order aberrations.

Administration, Topical↗

PubMed2003

[Analysis on potential years of life lost of automobile drivers in Jiangsu in 1990 - 1999].

OBJECTIVE: To describe the health status of automobile drivers and to define their potential years of life lost (PYLL) resulting from main death causes in Jiangsu in 1990 - 1999. METHODS: The Reed-Merrell method and Makham-Gompertz equation were used to compile the abridged truncate life tables. PYLL and rate of PYLL was used to analyse death causes in 1990 - 1999. RESULTS: (1) The life expectancy of drivers at age 20 was 55.36, which was 0.70 year less than that of non-drivers. (2) Rate of PYLL was 35.07 per thousand in drivers, and 42.65 per thousand in non-drivers, and the corresponding standard rates of PYLL were 42.45 per thousand and 41.14 per thousand, respectively. (3) Damage and toxicosis ranked number 4 in terms of proportionate mortality ratio, but ranked first with the rate of PYLL. CONCLUSION: Special attention should be paid to the health status of automobile drivers, especially to those who are middle aged. Diseases that made the greatest contributions to drivers' "earlier death" were damage and toxicosis.

Accidents, Traffic↗