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Biomedical subjects

Xinfeng Liu

Publications and source records attributed to Xinfeng Liu.

7 recordsLinked to original sources
PubMed2007

Cognitive performance after carotid angioplasty and stenting with brain protection devices.

OBJECTIVE: Neuropsychological outcomes after carotid endarterectomy (CEA) have been investigated extensively. However, cognitive impacts of carotid angioplasty and stenting (CAS), an emerging alternative to CEA, have not been studied. This study is aimed at investigating pattern and degree of cognitive changes after CAS among patients with high-grade carotid stenosis. PATIENTS AND METHODS: Fifty-four patients with high-grade carotid artery stenosis and received elective CAS were followed. Sixty-six patients with similar medical conditions requiring carotid angiography (CAG) were enrolled as controls. Cognitive functions among patients in both groups were evaluated at baseline and follow-ups utilizing a battery of neuropsychometric tests. Results were analysed by inter-group and within-group comparisons. RESULTS: There were no statistically significant differences between CAS and CAG patients regarding demographic characteristics, risk factors for stroke and baseline cognitive performance (p>0.05). CAS patients performed significantly better than CAG patients in Rey auditory verbal learning tests (RAVLT) at week 1 (41.2 +/- 5.2 versus 37.4 +/- 4.0, p<0.001) and week 12 follow-ups (43.3 +/- 7.7 versus 37.3 +/- 4.5, p<0.001). Comparison of z score also indicated CAS patients improved significantly more than CAG patients in RAVLT at both weeks 1 (1.08 +/- 1.29 versus 0.25 +/- 0.99, p<0.001) and 12 follow-ups (1.62 +/- 1.95 versus 0.05 +/- 1.02, p<0.001). CONCLUSION: CAS patients demonstrated improvement in verbal memory after procedures. Correction of cerebral hypoperfusion and reduction of artery-to-artery embolization after CAS are postulated responsible for the cognitive improvement.

Aged↗
PubMed2006

Recurrence after ischemic stroke in chinese patients: impact of uncontrolled modifiable risk factors.

BACKGROUND: Data concerning stroke occurrence and recurrence in China are extremely rare. This study was designed to analyze determinants of stroke recurrence in a cohort of Chinese patients. METHODS: Subjects were patients with ischemic stroke registered in the Nanjing Stroke Registry Program. Modifiable risk factors for stroke were identified and stratified into 3 levels: without, controlled and uncontrolled. Cox proportional hazard model was used to detect influence factors for stroke recurrence. RESULTS: First-year recurrence rate was 11.2% in the registered patients. Hypertension, atrial fibrillation (AF) and smoking were associated with increased risk of recurrence. Controlling hypertension and AF each halved recurrent risk (p < 0.001). Ceasing smoking for more than 1 year reduced hazard ratio of recurrence from 1.71 to 1.39 (p < 0.05). Controlling blood sugar level in diabetics did not significantly change recurrent risk (hazard ratio, 1.69 vs. 1.64, p > 0.05). CONCLUSIONS: The recurrence rate is higher in Chinese patients with ischemic stroke compared with the one reported in western populations. Failure to control some modifiable risk factors in Chinese patients may be responsible for this discrepancy.

Adult↗
PubMed2006

The effect of socioeconomic status on three-year mortality after first-ever ischemic stroke in Nanjing, China.

BACKGROUND: Low socioeconomic status (SES) is associated with increased mortality after stroke in developed countries. This study was performed to determine whether a similar association also exists in China. METHODS: A total of 806 patients with first-ever ischemic stroke were enrolled in our study. From August 1999 to August 2005, the three-year all-cause mortality following the stroke was determined. Level of education, occupation, taxable income and housing space were used as indicators for SES. Stepwise univariate and multivariate COX proportional hazards models were used to study the association between the SES measures and the three-year mortality. RESULTS: Our analyses confirmed that occupation, taxable income and housing space were significantly associated with three-year mortality after first-ever stroke. Manual workers had a significant hazard ratio of 5.44 (95% CI 2.75 to 10.77) for death within three years when compared with non-manual workers. Those in the zero income group had a significant hazard ratio of 5.35 (95% CI 2.95 to 9.70) and those in the intermediate income group 2.10 (95% CI 1.24 to 3.58) when compared with those in the highest income group. Those in two of the three groups with the smallest housing space also had significant hazard ratios of 2.06 (95% CI 1.16 to 3.65) and 1.68 (95% CI 1.12 to 2.52) when compared with those in group with the largest housing space. These hazard ratios remained largely unchanged after multivariate adjustment for age, gender, baseline cardiovascular disease risk factors, and stroke severity. The analyses did not confirm an association with educational level. CONCLUSION: Lower SES has a negative impact on the outcome of first-ever stroke in Nanjing, China. This confirms the need to improve preventive and secondary care for stroke among low SES groups.

Aged↗
PubMed2006

Subtypes and one-year survival of first-ever stroke in Chinese patients: The Nanjing Stroke Registry.

BACKGROUND: Morbidity and mortality of stroke have been investigated extensively in Western populations, while data concerning case fatality and cause of death after stroke are very limited in mainland China. This study aimed to analyze the 1-year survival and predictors of case fatality in Chinese patients with first-ever stroke. METHODS: Subjects are patients registered in the Nanjing Stroke Registry Program. Information concerning cardiovascular risk factors and stroke characteristics were collected, and patients were followed after registration. Ischemic strokes were classified according to TOAST criteria as large-artery atherosclerosis (LAA), cardiac embolism stroke (CES), small-vessel stroke (SVS), or other determined and undetermined causes (UND). One-year case fatality was analyzed by the Kaplan-Meier method, and predictors of case fatality were evaluated by the Cox proportional hazards model. RESULTS: A total of 752 patients with first-ever stroke were included, of which 142 (18.9%) were identified as intracerebral hemorrhage (ICH), 120 (16.0%) as LAA, 123 (16.4%) as SVS, 160 (21.3%) as CES and 216 (28.7%) as UND. The overall survival rate was 86.4% at the end of the 1-year follow-up. Patients with SVS have the highest survival rate (92.7%), followed by UND (89.4%), CES (88.1%) and LAA (84.2%). Patients with ICH have the lowest survival rate (76.8%). Survival rates of patients with different subtypes of stroke presented a significant difference (chi2 = 19.3, p < 0.001). For patients deceased during the first year after the index stroke, 33.3% of deaths were caused by the first stroke, 18.6% by recurrent stroke, 16.7% by cardiovascular comorbidities, 14.7% by nonvascular conditions and 16.7% died of undetermined causes. Advanced age, hypertension, hyperlipidemia, diabetes mellitus (DM), atrial fibrillation (AF), history of transient ischemic attack and cigarette smoking were associated with an increased risk of death 1 year after stroke. CONCLUSIONS: The case fatality rate and predictors for mortality of Chinese patients with first-ever stroke are similar to those reported for other populations. The significant influence of cardiovascular disease on the first-year survival rate emphasizes the importance of acute stroke management and control of hypertension, DM, AF and other predictors for decreasing case fatality and improving prognosis.

Adult↗
PubMed2006

Turbulent mixing with physical mass diffusion.

Simulated mixing rates of the Rayleigh-Taylor instability for miscible fluids with physical mass diffusion are shown to agree with experiment; for immiscible fluids with physical values of surface tension the numerical data lie in the center of the range of experimental values. The simulations are based on an improved front tracking algorithm to control numerical surface tension and on improved physical modeling to allow physical values of mass diffusion or surface tension. Compressibility, after correction for variable density effects, has also been shown to have a strong influence on mixing rates. In summary, we find significant dependence of the mixing rates on scale breaking phenomena. We introduce tools to analyze the bubble merger process and confirm that bubble interactions, as in a bubble merger model, drive the mixing growth rate.

Journal Article↗
PubMed2006

Influence of scale-breaking phenomena on turbulent mixing rates.

Simulations not seen before compare turbulent mixing rates for ideal fluids and for real immiscible fluids with experimental values for the surface tension. The simulated real fluid mixing rates lie near the center of the range of experimental values. A comparison to theoretical predictions relating the mixing rate, the bubble width, and the bubble height fluctuations based on bubble merger models shows good agreement with experiment. The ideal fluid mixing rate is some 50% larger, providing an example of the sensitivity of the mixing rate to physical scale breaking interfacial phenomena; we also observe this sensitivity to numerical scale-breaking artifacts.

Journal Article↗