Showing papers by "Honglei Chen published in 2007"

Plasma Urate and Risk of Parkinson's Disease

Abstract: Oxidative stress contributes to dopaminergic neuron degeneration in Parkinson’s disease (PD).Urate, a potent antioxidant, could be neuroprotective. To determine whether higher plasma concentrations of urate predict a reduced risk of PD, we conducted a nested case-control study among participants in the Health Professional Follow-up Study, a cohort comprising over 18,000 men who provided blood samples in 1993–95. 84 incident cases of PD were diagnosed through 2000 and each was randomly matched to two controls by year of birth, race, and time of blood collection. Rate ratios (RR) of PD according to quartile of uricemia were estimated using conditional logistic regression. The mean urate concentration was 5.7mg/dL among cases and 6.1mg/dL among controls (p=0.01). After adjusting for age, smoking, and caffeine, the RR (95 percent confidence interval [CI]) of PD for the highest quartile of uricemia compared to the lowest was 0.43 (0.18, 1.02; p-for-trend=0.017). This association was stronger in analyses excluding cases diagnosed within 4 years (median) from blood collection (RR=0.17; 95 percent CI: 0.04, 0.69; p-for-trend=0.010). These results suggest that high plasma urate concentrations may decrease risk of PD and raise the possibility that interventions to increase plasma urate may reduce risk and delay the progression of PD.

Peripheral Inflammatory Biomarkers and Risk of Parkinson's Disease

Abstract: Experimental and postmortem evidence indicates a role of neuroinflammation in the pathogenesis of Parkinson’s disease. The authors prospectively examined whether plasma concentrations of inflammatory biomarkers assessed before Parkinson’s disease diagnosis were predictive of future risk of the disease in a nested case-control study in the United States (1993–2002), including 84 incident cases and 165 matched controls. Blood was collected from patients on average 4.3 years before the diagnosis. After adjustment for potential confounders, higher level of interleukin-6 was associated with a greater risk of Parkinson’s disease. Compared with the lowest quintile, the odds ratios were 1.5 for the second, 1.6 for the third, 2.7 for the fourth, and 3.4 for the fifth quintiles (p for trend ¼ 0.03). In contrast, concentrations of other inflammatory biomarkers including C-reactive protein, fibrinogen, and tumor necrosis factor-a receptors were not related to the risk. These data suggest that men with high plasma concentrations of interleukin-6 have an increased risk of developing Parkinson’s disease. However, this finding should be interpreted with caution because of the small sample size and the lack of associations with other biomarkers of inflammation. biological markers; C-reactive protein; inflammation; interleukin-6; odds ratio; Parkinson disease; tumor necrosis factor-a Abbreviations: IL, interleukin; TNF, tumor necrosis factor. Microglia-mediated neuroinflammation has been hypothesized to play an important role in the pathogenesis of Parkinson’s disease, primarily based on findings from postmortem studies and animal experiments (1, 2). Consistently, concentrations of proinflammatory cytokines such as interleukin (IL)-1b, IL-2, IL-6, and tumor necrosis factor (TNF)-a were elevated in the brain and cerebral spinal fluid of Parkinson’s disease patients (3). Two small studies further showed plasma elevations of some of these cytokines when comparing Parkinson’s disease patients with controls (4, 5). However, these studies involved prevalent cases and provided little information on whether prediagnostic levels of inflammatory biomarkers are predictive of future risk of Parkinson’s disease. Therefore, by taking advantage of the prospective Health Professionals Follow-up Study, we conducted a nested case-control investigation to examine whether peripheral elevations in inflammatory biomarkers assessed years before disease diagnoses were associated with greater risk of Parkinson’s disease.

Head Injury and Amyotrophic Lateral Sclerosis

Abstract: Recent data showed that soccer players in Italy had an unusually high risk of amyotrophic lateral sclerosis (ALS) and that repeated head trauma might have contributed to this increase. The authors examined whether head injury was related to ALS risk in a case-control study of 109 New England ALS cases diagnosed in 1993-1996 and 255 matched controls. They also conducted a meta-analysis of the published literature. Overall, ever having experienced a head injury was nonsignificantly associated with a higher ALS risk. When compared with persons without a head injury, a statistically significant ALS risk elevation was found for participants with more than one head injury (odds ratio (OR) = 3.1, 95 percent confidence interval (CI): 1.2, 8.1) and patients who had had a head injury during the past 10 years (OR = 3.2, 95 percent CI: 1.0, 10.2). For participants who had had multiple head injuries with the latest occurring in the past 10 years, risk was elevated more than 11-fold. The meta-analysis also indicated a moderately elevated risk of ALS among persons with previous head injuries (OR = 1.7, 95 percent CI: 1.3, 2.2). In this study population, physical injuries to other body parts, including the trunk, arms, or legs, were not related to ALS risk. These data support the notion that head injury may increase the risk of ALS.

Hypertension, hypercholesterolemia, diabetes, and risk of Parkinson disease

Abstract: Objective: To determine whether history of hypertension, hypercholesterolemia, or diabetes is associated with risk of Parkinson disease (PD). Methods: Prospective study among participants in two large cohorts: the Nurses’ Health Study (121,046 women) and the Health Professionals Follow-up Study (50,833 men). Mean duration of follow-up was 22.9 years in women, aged 30 to 55 years at baseline, and 12.6 years in men, aged 40 to 75 years at baseline. Relative risks (RRs) of PD were estimated from a Cox proportional hazards model adjusting for potential confounders. Results: We identified a total of 530 incident cases of PD during the follow-up. Risk of PD was not associated with self-reported history of hypertension (RR = 0.96, 95% CI = 0.80 to 1.15), high cholesterol (RR = 0.98, 95% CI = 0.82 to 1.19), or diabetes (RR = 1.04, 95% CI = 0.74 to 1.46), after adjusting for age and smoking in pack-years. Risk of PD decreased modestly with increasing levels of self-reported total cholesterol (RR for a 50-mg/dL increase in total cholesterol = 0.86, 95% CI = 0.78 to 0.95, p for trend = 0.02), but use of cholesterol-lowering drugs was not associated with PD risk (RR comparing users with nonusers = 0.85, 95% CI = 0.59 to 1.23). Among individuals with PD, systolic blood pressure was similar to noncases up to the time of diagnosis but declined afterward. Conclusions: Results of this large prospective study suggest that Parkinson disease risk is not significantly related to history of hypertension, hypercholesterolemia, or diabetes but may modestly decline with increasing blood cholesterol levels. GLOSSARY: ACE = angiotensin-converting enzyme; BMI = body mass index; DBP = diastolic blood pressure; HPFS = Health Professionals Follow-up Study; METS = metabolic equivalent tasks; NHS = Nurses’ Health Study; NSAID = nonsteroidal anti-inflammatory drug; PD = Parkinson disease; RR = relative risk; SBP = systolic blood pressure.

Lower low-density lipoprotein cholesterol levels are associated with Parkinson's disease.

Abstract: The apolipoprotein E (APOE) epsilon2 allele has been associated with both Parkinson's disease (PD) and lower low-density lipoprotein cholesterol (LDL-C). We tested the hypothesis that lower LDL-C may be associated with PD. This case-control study used fasting lipid profiles obtained from 124 PD cases and 112 controls. The PD cases were recruited from consecutive cases presenting at our tertiary Movement Disorder Clinic, and the controls were recruited from the spouse populations of the same clinic. Multivariate odds ratios (ORs) and 95% confidence intervals (CIs) were calculated from unconditional logistic regressions, adjusting for age, gender, smoking status, and use of cholesterol-lowering agents. Lower LDL-C concentrations were associated with a higher occurrence of PD. Compared with participants with the highest LDL-C (> or =138 mg/dL), the OR was 2.2 (95% CI = 0.9-5.1) for participants with LDL-C of 115 to 137, 3.5 (95% CI = 1.6-8.1) for LDL-C of 93 to 114, and 2.6 (95% CI = 1.1-5.9) for LDL-C of < or = 92. Interestingly, use of either cholesterol-lowering drugs, or statins alone, was related to lower PD occurrence. Thus, our data provide preliminary evidence that low LDL-C may be associated with higher occurrence of PD, and/or that statin use may lower PD occurrence, either of which finding warrants further investigation.

Consumption of Dairy Products and Risk of Parkinson's Disease

Abstract: The authors prospectively investigated the association between intake of dairy products and risk of Parkinson's disease among 57,689 men and 73,175 women from the American Cancer Society's Cancer Prevention Study II Nutrition Cohort. A total of 250 men and 138 women with Parkinson's disease were identified during follow-up (1992-2001). Dairy product consumption was positively associated with risk of Parkinson's disease: Compared with the lowest intake quintile, the corresponding relative risks for quintiles 2-5 were 1.4, 1.4, 1.4, and 1.6 (95 percent confidence interval (CI): 1.1, 2.2; p for trend = 0.05). A higher risk among dairy product consumers was found in both men and women, although the association in women appeared nonlinear. Meta-analysis of all prospective studies confirmed a moderately elevated risk of Parkinson's disease among persons with high dairy product consumption: For extreme intake categories, relative risks were 1.6 (95 percent CI: 1.3, 2.0) for both sexes, 1.8 for men (95 percent CI: 1.4, 2.4), and 1.3 for women (95 percent CI: 0.8, 2.1). These data suggest that dairy consumption may increase the risk of Parkinson's disease, particularly in men. More studies are needed to further examine these findings and to explore underlying mechanisms.

Temporal relationship between cigarette smoking and risk of Parkinson disease.

Abstract: Objective: To characterize further the relationship between smoking history and Parkinson disease (PD) risk by considering temporal and qualitative features of smoking exposure, including duration, average intensity, and recentness, as well as the relative importance of smoking during different periods of life. Methods: We prospectively assessed incident PD from 1992 to 2001 among 79,977 women and 63,348 men participating in the Cancer Prevention Study II Nutrition Cohort, according to their cigarette smoking status and lifetime smoking histories. Results: During follow-up, 413 participants had definite or probable PD confirmed by their treating neurologists or medical record review. Compared with never smokers, former smokers had a relative risk (RR) of 0.78 (95% CI 0.64 to 0.95) and current smokers had an RR of 0.27 (95% CI 0.13 to 0.56). On average, participants with more years smoked, more cigarettes per day, older age at quitting smoking, and fewer years since quitting smoking had lower PD risk. The relative risks and trends did not vary significantly by sex. The cumulative incidence of PD was lowest among participants who quit smoking at later ages. A 30% to 60% decreased risk of PD was apparent for smoking as early as 15 to 24 years before symptom onset, but not for smoking 25 or more years before onset. Conclusions: The lower risk of Parkinson disease among current and former smokers varied with smoking duration, intensity, and recentness. The dependence of this association on the timing of smoking during life is consistent with a biologic effect.

Erectile Function and Risk of Parkinson's Disease

Abstract: Erectile dysfunction is common among individuals with Parkinson's disease, but it is unknown whether it precedes the onset of the classic features of Parkinson's disease. To address this question, the authors examined whether erectile dysfunction was associated with Parkinson's disease risk in the Health Professionals Follow-up Study. Analyses included 32,616 men free of Parkinson's disease at baseline in 1986 who in 2000 completed a retrospective questionnaire with questions on erectile dysfunction in different time periods. Relative risks were computed using Cox proportional hazards models adjusting for age, smoking, caffeine intake, history of diabetes, and other covariates. Among men who reported their erectile function before 1986, 200 were diagnosed with Parkinson's disease during 1986-2002. Men with erectile dysfunction before 1986 were 3.8 times more likely to develop Parkinson's disease during the follow-up than were those with very good erectile function (relative risk = 3.8, 95% confidence interval: 2.4, 6.0; p < 0.0001). Multivariate-adjusted relative risks of Parkinson's disease were 2.7, 3.7, and 4.0 (95% confidence interval: 1.4, 11.1; p = 0.008) for participants with first onset of erectile dysfunction (before 1986) at 60 or more, 50-59, and less than 50 years of age, respectively, relative to those without erectile dysfunction. In conclusion, in this retrospective analysis in a large cohort of men, the authors observed that erectile dysfunction was associated with a higher risk of developing Parkinson's disease.

Super-Resolution Processing for Polarimetric Synthetic Aperture Radar Tomography

Abstract: In polarimetric SAR interferometry, fully-polarimetric measurements are obtained along multiple interferometric tracks and used to generate three-dimensional tomographic images of a scene of interest. The objective is to utilize the polarimetric diversity of the targets to separate multiple targets within a single pixel. In this study, a new technique known as Vector Linear Prediction (VLP) is developed and used to perform polarimetric aperture extrapolation with measurements from a single baseline SAR interferometer. The VLP method extends scalar, linear prediction-based extrapolation to coherent, multi-channel data such as polarimetric SAR interferometric measurements. The interferometric phase estimates, which reflect the elevation of the scattering centers, are obtained for both the ground and vegetation components. The phase difference between the two components is shown to be consistent with the vegetation cover in the region under study. In the future, this technique will be applied to multi-baseline SAR measurements to produce tomographic images of the scenes being imaged.