Biomedical subjects

Shiquan Ren

Publications and source records attributed to Shiquan Ren.

4 recordsLinked to original sources

PubMed2006

Intraclass correlation coefficients and bootstrap methods of hierarchical binary outcomes.

Intraclass correlation coefficients are designed to assess consistency or conformity between two or more quantitative measurements. When multistage cluster sampling is implemented, no methods are readily available to estimate intraclass correlations of binomial-distributed outcomes within a cluster. Because statistical distribution of the intraclass correlation coefficients could be complicated or unspecified, we propose using a bootstrap method to estimate the standard error and confidence interval within the framework of a multilevel generalized linear model. We compared the results derived from a parametric bootstrap method with those from a non-parametric bootstrap method and found that the non-parametric method is more robust. For non-parametric bootstrap sampling, we showed that the effectiveness of sampling on the highest level is greater than that on lower levels; to illustrate the effectiveness, we analyse survey data in China and do simulation studies.

Biometry↗

PubMed2006

Effect of long-term cocaine use on regional left ventricular function as determined by magnetic resonance imaging.

This study examined left ventricular (LV) regional midwall circumferential strain by cardiac tagged magnetic resonance imaging in 32 long-term cocaine users and 14 nonusers. Most of the LV segmentations in the cocaine users had less average circumferential strain in the systolic and diastolic phases. The average diastolic strain in 5 ventricular segmentations was significantly less in the cocaine users (p<0.05). In conclusion, long-term cocaine use may be associated with regional LV dysfunction, especially diastolic dysfunction.

Adult↗

PubMed2005

Age, gender and metabolic syndrome-related coronary heart disease in U.S. adults.

BACKGROUND: Metabolic syndrome (MetS), a clustering of several prominent risk factors for atherosclerosis, is common among U.S. populations. The contribution of MetS to the prevalence of coronary heart disease (CHD) in different age-gender groups is currently unknown. METHODS: MetS was defined according to the definition of the National Cholesterol Education Program Adult Treatment Panel III. CHD was defined as having had a diagnosed heart attack in self-reported medical history. Data from the Third National Health and Nutrition Examination Survey (NHANES III) were used to evaluate the MetS-associated CHD prevalences in different age-gender subpopulations, which include 35- to 54-year-old women, 55- to 74-year-old women, 35- to 54-year-old men, and 55- to 74-year-old men. RESULTS: The prevalences of MetS in these 4 age-gender subpopulations are 21%, 24%, 39%, and 38%, respectively. The odds ratios (and the 95% confidence intervals) of MetS to increased CHD in each subpopulations are 1.05 (0.40-2.79), 1.95 (1.19-3.20), 2.22 (1.03-4.81), and 1.96 (1.41-2.70), respectively. CONCLUSIONS: MetS-associated CHD prevalence in women aged 35-54 years is almost the same as in the control, whereas in women aged 55-74 and in men aged 35-54 or 55-74, this prevalence is about 2-fold that of the control. Endogenous estrogen may play a role in suppressing the pro-atherosclerotic effects of MetS-related risk factors, but further studies are needed for a more certain conclusion.

Adult↗

PubMed2003

Factors associated with accelerated atherosclerosis in HIV-1-infected persons treated with protease inhibitors.

Recent evidence suggests that as a group protease inhibitors (PIs) may accelerate certain factors associated with atherosclerosis. The objective of this study was to evaluate the effect of individual PIs (indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir) on certain factors associated with atherosclerosis. Persons who took saquinavir and/or ritonavir were compared with those on other PIs. Between May 2000 and July 2001, the lipid profiles, C-reactive protein (CRP) levels, coronary artery calcium (CAC) scores, and blood cell morphologic parameters were measured in 98 black adult participants aged 25 to 45 years with HIV-1 infection in Baltimore, Maryland. Among these 98, there were 55 (56.1%) taking PIs. Students' t-test and chi2 test were used to detect the between-group differences. Study participants in both the PI and non-PI groups were similar in age, sex, body mass index, blood pressure, red and white blood cell counts, time since HIV diagnosis, and duration on anti-retroviral therapy. Compared with those who took non-PI regimens, those who took indinavir, nelfinavir, or saquinavir had significantly higher levels of mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH). Those taking any PI had significantly higher total cholesterol and low-density lipoprotein. Those taking nelfinavir, ritonavir, or saquinavir were more likely to have a higher CAC score (>5) than those on non-PI regimens. There were no differences in the lipid profiles, MCV, MCH, CRP, and CAC between those taking saquinavir and/or ritonavir and those taking other PIs. Overall, the changes noted might lead to anticipation of clinical changes linked to accelerated atherosclerosis in patients on PIs.

Adult↗