A simple alkali lysis method for Plasmodium falciparum DNA extraction from filter paper blood samples.

A fast, simple, easy, efficient, and inexpensive method for DNA extraction from malaria parasites collected on filter paper would be very useful for molecular surveillance. The quality and quantity of DNA are critical to molecular diagnosis and analysis. Here, we developed a simple alkali lysis method for DNA extraction from blood samples on filter paper. The results showed that 10-50 mM NaOH and deionized water all effectively isolated parasite DNA at higher parasitemia, as witnessed by successful PCR amplification, while at a parasitemia of 0.01%, the 10 mM NaOH lysis condition generated the best results. Furthermore, DNA extracted by this method was successfully used to amplify a fragment of > 2000 bp. This method successfully extracted DNA from 1 µl of blood at a parasitemia as low as 0.0001% (equivalent to 5 parasites /µl). The DNA isolated by the 10 mM NaOH lysis method was stable to yield PCR products after storage at 4 °C or - 20 °C for 12 months. These results indicate that this alkali lysis method is simple, effective, sensitive, and inexpensive for isolating stable Plasmodium DNA from dried blood spots on filter paper.

Association between physical exercise and stroke recurrence among first-ever ischemic stroke survivors.

The relationship between exercise and stroke recurrence is controversial. This study was designed to test whether an association exists between exercise and ischemic stroke recurrence in first-ever ischemic stroke survivors. Data were collected from January 2010 to June 2016. Baseline information was obtained during face-to-face interviews, and follow-up phone interviews were conducted every 3 months. Exercise type, frequency, intensity, and duration were recorded. Discrete-time survival analysis was used to determine the relationship between exercise and stroke recurrence. 760 first-ever ischemic stroke survivors who were able to exercise were enrolled. After adjusting for covariates, patients who exercised 3.5-7 h per week and more than 7 h per week had a lower relapse risk than patients who did not exercise (3.5-7: OR 0.415; > 7: OR 0.356). Moreover, if the fluctuation of exercise duration was over 4 h, the patients had a higher risk of stroke recurrence than those with variability of less than 2 h (OR 2.153, P = 0.013). Stroke survivors who engage in long-term regular mild exercise (more than 5 sessions per week and lasting on average 40 min per session) have a lower recurrence rate. Irregular exercise increases the risk of stroke recurrence.

Association between dynamic obesity and mortality in patients with first-ever ischemic stroke: A hospital-based prospective study.

Although obesity is an established risk factor of primary stroke, the association between obesity and post-stroke mortality remains unclear. The aim of this study was to investigate the association between dynamic obesity status and mortality in survivors of their first stroke in China.Of 775 patients with first-ever ischemic stroke included in a longitudinal study, 754 patients were included in this study and categorized into 4 categories of body mass index (BMI) (underweight, normal weight, overweight, and obese) and 2 categories of waist circumference (WC) (normal WC and abdominal obesity) according to standard Chinese criteria. The mortality information and obesity status were obtained via telephone follow-up every 3 months, beginning in 2010 through 2016. Time-dependent Cox proportional hazards models were used to estimate the unadjusted and adjusted hazard ratios (HRs) for the relationship between all-cause mortality and dynamic obesity status.Of 754 patients, 60.87% were male, and the overall mean age was 61.45 years. After adjusting for possible confounders, significant inverse associations were identified between BMI and WC and all-cause mortality. Compared with those with normal BMI or WC, those with abdominal obesity or overweight had a significantly lower risk of all-cause mortality (HR and 95% confidence intervals [CIs]: .521 [.303-.897] and 0.545 [.352-.845], respectively), whereas patients with underweight had the highest risk and those with obesity had lower risk of mortality, though it was not statistically significant (1.241 [.691-2.226] and .486 [.192-1.231], respectively).Overweight and abdominal obesity were paradoxically associated with reduced risk of mortality in patients who survived their first-ever ischemic stroke in China. Future prospective studies must look at evaluating the role of obesity in different stroke subtypes and devise appropriate weight-management strategies for optimal prognoses in secondary prevention in these survivors.

Associations between Lesion Locations and Stroke Recurrence in Survivors of First-ever Ischemic Stroke: A Prospective Cohort Study.

Several studies have indicated that stroke survivors with multiple lesions or with larger lesion volumes have a higher risk of stroke recurrence. However, the relationship between lesion locations and stroke recurrence is unclear. We conducted a prospective cohort study of first-ever ischemic stroke survivors who were consecutively enrolled from January 2010 to December 2015. Stroke recurrence was assessed every 3 months after post-discharge via telephone interviews by trained interviewers. Lesion locations were obtained from hospital-based MRI or CT scans and classified using two classification systems that were based on cerebral hemisphere or vascular territory and brain anatomical structures. Flexible parametric survival models using the proportional hazards scale (PH model) were used to analyze the time-to-event data. Among 633 survivors, 63.51% (n=402) had anterior circulation ischemia (ACI), and more than half of all ACIs occurred in the subcortex. After a median follow-up of 2.5 years, 117 (18.48%) survivors developed a recurrent stroke. The results of the multivariate PH model showed that survivors with non-brain lesions were at higher risk of recurrence than those with right-side lesions (HR, 2.79; 95%CI, 1.53, 5.08; P=0.001). There was no increase in risk among survivors with left-side lesions (HR, 0.97; 95%CI, 0.53, 1.75; P=0.914) or both-side lesions (HR, 1.24; 95%CI, 0.75, 2.07; P=0.401) compared to those with right-side lesions. Additionally, there were no associations between stroke recurrence and lesion locations that were classified based on vascular territory and brain anatomical structures. It was concluded that first-ever ischemic stroke survivors with non-brain lesion had higher recurrence risk than those with right-side lesion, although no significant associations were found when the lesion locations were classified by vascular territory and brain anatomical structures.

Risk scoring system with MRI for intraoperative massive hemorrhage in placenta previa and accreta.

BACKGROUND: Placenta previa and accreta are serious obstetric conditions that are associated with a high risk of intraoperative massive hemorrhage. PURPOSE: To develop a scoring system for intraoperative massive hemorrhage combining MRI and clinical characteristics to predict the risk of massive hemorrhage in placenta previa and accreta STUDY TYPE: Retrospective cohort study. SUBJECTS: In all, 374 patients consisting of 259 patients with placenta previa and accreta after previous cesarean section (CS) for the derivation cohort and 115 patients for the validation cohort. FIELD STRENGTH/SEQUENCE: 1.5T single-shot fast spin-echo sequence. [Correction added on October 23, 2019, after first online publication: The field strength in the preceding sentence was corrected.] ASSESSMENT: Using the derivation cohort, clinical and MRI data were collected and multivariable logistic regressions analysis was conducted to develop a scoring system for prediction of intraoperative massive bleeding (blood loss volume > 2000 mL). Finally, the scoring system was validated on 115 patients. STATISTICAL TESTS: Student's t-test, Mann-Whitney U-test, X 2 statistics, multivariable analysis, and receiver operating characteristic (ROC) analysis. RESULTS: Ten indicators, including clinically maternal age (1 point), preoperative hemoglobin level (1 point), gravidity number (1 point), number of CS (1 point), and MRI T2 dark intraplacental bands (4 points), cervical canal length (3 points), placenta thickness on the uterine scar area (4 points), empty vascular shadow of the uterus (1 point), low signal discontinuity in the muscular layer of the posterior wall of the bladder (6 points) and attachment position of the placenta (1 point) were imputed. From the ROC analysis, a total score of 7 points was identified as the optimal cutoff value, allowing good differentiation of intraoperative massive bleeding in the derivation cohort (AUC, 0.863; 95% confidence interval [CI]: 0.811-0.916) and in the validation cohort (AUC, 0.933; 95% CI: 0.885-0.980). DATA CONCLUSION: The scoring system for intraoperative massive hemorrhage consists of MRI and clinical indicators, and using a cutoff value of 7 points for a high risk of massive bleeding, the developed scoring system could accurately assess the risk of intraoperative massive hemorrhage in patients with placenta previa and accreta. This scoring system can potentially reduce the incidence of intraoperative massive bleeding by identifying patients at high risk. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2020;51:947-958.

Time to recurrence after first-ever ischaemic stroke within 3 years and its risk factors in Chinese population: a prospective cohort study.

OBJECTIVE: This study aimed to estimate the time of recurrent ischaemic stroke events among the first 3 years of follow-up after hospitalisation discharge. STUDY DESIGN: A prospective cohort study. SETTING: The research was conducted in the Department of Neurology at a tertiary hospital, Chengdu of China, from January 2010 to June 2016. OUTCOME MEASURES: We estimated the restricted mean survival time (RMST) of ischaemic stroke recurrence for the first 3 years after discharge. Basic sociodemographic characteristics and major potential risk factors for recurrence were collected using a semistructured questionnaire. Regression analysis of RMST was used to identify risk factors of recurrent stroke. PARTICIPANTS: Patients hospitalised with first-ever ischaemic stroke were eligible for this study. Patients with severe cognitive impairment were excluded. RESULTS: We included 641 surviving patients who were followed up for 3 years. Stroke recurrence occurred in 115 patients, including 16 patients who died of stroke recurrence. The cumulative risk of stroke recurrence rate was 11.51% (9.20%-14.35%) at 1 year, 16.76% (13.96%-20.05%) at 2 years and 20.07% (17.00%-23.61%) at 3 years. Modified Rankin Scale (mRS) score ≥3 thus resulted in the recurrence time loss, which was 0.22 months (p=0.008) at 6 months, 0.61 months (p=0.004) at 1 year, 1.49 months (p=0.007) at 2 years and 2.46 months (p=0.008) at 3 years. It is similar with the effects of drug adherence after stroke. The recurrence time of patients ≥75 years at 3 years was 2.02 months (p=0.220) less than that of those aged <55 years. CONCLUSION: In China, the time of first recurrence varies among different patients with ischaemic stroke. The mRS and the level of drug adherence after stroke are important risk factors of stroke recurrence.

[Association between drinking and all-cause mortality in patients with ischemic stroke].

OBJECTIVE: To investigate the association between alcohol drinking and all-cause death in patients with ischemic stroke. METHODS: Between January, 2010 and July, 2018, consecutive patients with first-episode ischemic stroke admitted in the West China Hospital, Sichuan University were enrolled, and all the patients were followed up every 3 months.Chi-square test was used to compare the differences in the baseline characteristics between the pre-stroke drinkers and the nondrinkers.The Cox regression model was used to analyze the effects of drinking status, drinking years, drinking frequency, average single alcohol intake before stroke and drinking status during the follow-up period on the mortality of patients after discharge. RESULTS: A total of 855 patients with ischemic stroke were enrolled, and deaths occurred in 140 of these patients.Chi-square test showed significant differences in gender (P < 0.001), weekly physical exercise time (P=0.035), smoking (P < 0.001), and heart disease (P < 0.001) between the pre-stroke drinkers and nondrinkers.Multivariate Cox regression analysis showed that drinking during the follow-up period (P=0.001), drinking for less than 28 years before stroke (P=0.035) and a moderate drinking frequency (5 to 20 times per month for males and 4 to 9 times per month for females; P=0.030) were associated with a lowered risk of death after discharge.No significant effects of pre-stroke drinking status or average single alcohol intake were found on death after ischemic stroke. CONCLUSIONS: The drinking years and drinking frequency before stroke and drinking status during the follow-up period are related to the all-cause mortality in patients with ischemic stroke.Investigations of the more specific variables of drinking behaviors during the follow-up period are needed to further clarify the association between drinking and death after ischemic stroke.

Translation, cross-cultural adaptation, and validation of the chinese version of the 15-item myasthenia gravis quality of life questionnaire.

INTRODUCTION: We sought to translate, cross-culturally adapt, and evaluate the internal consistency and validity of the Chinese version of the 15-Item Myasthenia Gravis Quality of Life (MG-QOL15). METHODS: Translation and cross-cultural adaptation of the MG-QOL15 were performed. We used Cronbach's α to test internal consistency, one-way analysis of variance to test construct validity, and Pearson or Spearman correlations to test discriminant and concurrent validity. RESULTS: We enrolled 168 outpatients. Internal consistency was excellent (Cronbach's α = 0.928). The MG-QOL15 discriminated MG severity as stratified by the MG Composite (MGC; P < 0.001) and Osserman class (P = 0.01). Concurrent validity was low to moderate with the subscales of the 36-item Short Form (-0.31 to ∼-0.59), MGC (r = 0.46), and Myasthenia Gravis Activities of Daily Living profile (r = 0.54). DISCUSSION: The Chinese MG-QOL15 showed comparable construct, discriminant and concurrent validity, and internal consistency with to the original version. Muscle Nerve 59:95-99, 2019.

[Relative Survival of Patients with Ischemic Stroke].

OBJECTIVE: To estimate the relative survival ratio of patients with ischemic stroke and its risk factors. METHODS: Lifetable and Ederer Ⅱ methods were used to estimate the relative survival ratio of patients with ischemic stroke. The Poission error structure model was adopted to determine the risk factors associated with survival. RESULTS: The patients had 99%, 98%, 98% and 99% relative survival ratio 1 year, 3 years, 5 years and 7 years after stroke, respectively. The relative excess risk of death increased with age [53-62 yr. vs. <53 yr., relative excess risk (RER=26.975, 95%CI: 1.668-410.90, P=0.020 1], higher mRS scores (≥3 vs. <3 points, RER=14.700, 95%CI: 1.05-206.45, P=0.047 3), and under body mass (vs. normal body mass, RER=10.082, 95%CI: 2.076-48.958, P=0.004 2). CONCLUSION: Ischemic stroke patients have a good prognosis, with slightly lower survival rates than the matched general populations. Those who are older, under body mass, and have a higher mRS score have lower survival rates.

Comparison of the flexible parametric survival model and Cox model in estimating Markov transition probabilities using real-world data.

BACKGROUND AND OBJECTIVE: Markov micro-simulation models are being increasingly used in health economic evaluations. An important feature of the Markov micro-simulation model is its ability to consider transition probabilities of heterogeneous subgroups with different risk profiles. A survival analysis is generally performed to accurately estimate the transition probabilities associated with the risk profiles. This study aimed to apply a flexible parametric survival model (FPSM) to estimate individual transition probabilities. MATERIALS AND METHODS: The data were obtained from a cohort study investigating ischemic stroke outcomes in Western China. In total, 585 subjects were included in the analysis. To explore the goodness of fit of the FPSM, we compared the estimated hazard ratios and baseline cumulative hazards, both of which are necessary to the calculate individual transition probabilities, and the Markov micro-simulation models constructed using the FPSM and Cox model to determine the validity of the two Markov micro-simulation models and cost-effectiveness results. RESULTS: The flexible parametric proportional hazards model produced hazard ratio and baseline cumulative hazard estimates that were similar to those obtained using the Cox proportional hazards model. The simulated cumulative incidence of recurrent ischemic stroke and 5-years cost-effectiveness of Incremental cost-effectiveness Ratios (ICERs) were also similar using the two approaches. A discrepancy in the results was evident between the 5-years cost-effectiveness and the 10-years cost-effectiveness of ICERs, which were approximately 0.9 million (China Yuan) and 0.5 million (China Yuan), respectively. CONCLUSIONS: The flexible parametric survival model represents a good approach for estimating individual transition probabilities for a Markov micro-simulation model.

[Health Utility of Patients with Stroke Measured by EQ-5D and SF-6D].

OBJECTIVE: To compare EQ-5D and SF-6D for measuring health utility of stroke patients in health economic evaluation studies. METHODS: A prospective cohort study was conducted on 596 stroke patients in the West China Hospital of Sichuan University from 2010 to 2016. Data were collected at baseline through face to face interviews and at the follow-up stages through telephone interviews with a three-month interval. EQ-5D and SF-6D were used for measuring health utility scores of the participants. The consistency of the two instruments was assessed using Bland-Altman plot and Intraclass correlation coefficient (ICC) . Logistic regression models were established to identify predictors of health utility. RESULTS: The participants had a mean utility score of 0.78 (95% confidence interval:0.76, 0.80) in EQ-5D,compared with 0.74 (95% confidence interval: 0.73, 0.76) in SF-6D,and a median (interquartile range) of 0.86 (0.68, 1.00) in EQ-5D and 0.73 (0.62, 0.86) in SF-6D. The 95% limits of agreement between the two instruments ranged from -0.28 to 0.35,with an ICC of 0.67 (95% confidence interval: 0.62,0.71). EQ-5D had a higher ceiling effect. The health utility score of stroke patients changed there rapidly in acute phase (less than 3 months) but barely changed there after.Severity of stroke was a major predictor of health utility scores. CONCLUSION: The two instruments generate inconsistent results in health utility. SF-6D is better for measuring health utility in patients with stroke in China.