BackgroundAlthough the problem-based learning (PBL) emerged in 1969 and was soon widely applied internationally, the rapid development in China only occurred in the last 10 years. This study aims to compare the effect of PBL and lecture-based learning (LBL) on student course examination results for introductory Chinese undergraduate medical courses.MethodsRandomized and nonrandomized controlled trial studies on PBL use in Chinese undergraduate medical education were retrieved through PubMed, the Excerpta Medica Database (EMBASE), Chinese National Knowledge Infrastructure (CNKI) and VIP China Science and Technology Journal Database (VIP-CSTJ) with publication dates from 1st January 1966 till 31 August 2014. The pass rate, excellence rate and examination scores of course examination were collected. Methodological quality was evaluated based on the modified Jadad scale. The I-square statistic and Chi-square test of heterogeneity were used to assess the statistical heterogeneity. Overall RRs or SMDs with their 95% CIs were calculated in meta-analysis. Meta-regression and subgroup meta-analyses were also performed based on comparators and other confounding factors. Funnel plots and Egger’s tests were performed to assess degrees of publication bias.ResultsThe meta-analysis included 31studies and 4,699 subjects. Fourteen studies were of high quality with modified Jadad scores of 4 to 6, and 17 studies were of low quality with scores of 1 to 3. Relative to the LBL model, the PBL model yielded higher course examination pass rates [RR = 1.09, 95%CI (1.03, 1.17)], excellence rates [RR = 1.66, 95%CI (1.33, 2.06)] and examination scores [SMD = 0.82, 95%CI (0.63, 1.01)]. The meta-regression results show that course type was the significant confounding factor that caused heterogeneity in the examination-score meta-analysis (t = 0.410, P<0.001). The examination score SMD in “laboratory course” subgroup [SMD = 2.01, 95% CI: (1.50, 2.52)] was higher than that in “theory course” subgroup [SMD = 0.72, 95% CI: (0.56, 0.89)].ConclusionsPBL teaching model application in introductory undergraduate medical courses can increase course examination excellence rates and scores in Chinese medical education system. It is more effective when applied to laboratory courses than to theory-based courses.

Background The prognostic roles of neutrophil‐to‐lymphocyte ratio (NLR) and platelet‐to‐lymphocyte ratio (PLR) have been reported in head and neck squamous cell carcinoma (HNSCC), but their results remain controversial. Methods A total of 25 literatures with 28 cohorts involving 6847 HNSCC patients were included. The hazard ratio (HR) was pooled with 95% confidence interval (CI) using fixed‐effects or random‐effects models. Results High pretreatment NLR predicted poor overall survival (OS: HR = 1.68; 95% CI = 1.39‐2.03; P < .001), disease‐free survival (DFS: HR = 1.76; 95% CI = 1.42‐2.17; P < .001), progression‐free survival (PFS: HR = 1.53; 95% CI = 1.09‐2.14; P = .014), and cancer‐specific survival (CSS: HR = 1.45; 95% CI = 1.23‐1.71; P < .001) in HNSCC. However, the association between PLR and OS or DFS was not statistically significant. Conclusion The NLR can serve as a potential prognostic biomarker for patients with HNSCC.

Alzheimer's disease (AD), the most common form of dementia, is characterized by the presence of excessive deposits of aggregated amyloid-beta (Abeta), which is derived from the amyloid-beta protein precursor (AbetaPP) following processing by beta- and gamma-secretase. Metal elements are implicated in the pathophysiology of AD. Magnesium affects many biochemical mechanisms vital for neuronal properties and synaptic plasticity, and magnesium levels were reported to be decreased in various tissues including brain of AD patients. However, the exact role of magnesium in the neurodegenerative process of AD remains elusive. In this study, we investigated the effects of physiological (0.8 mM, as normal control), low (0-0.4 mM), and high (1.2-4.0 mM) concentrations of extracellular magnesium ([Mg2+]o) on AbetaPP processing and Abeta secretion. Here we show the effects of varying [Mg2+]o on AbetaPP processing is time- and dose-dependent. After 24 h treatment, high [Mg2+]o increased C-terminal fragment-alpha (CTFalpha) levels and soluble alpha-secretase cleaved AbetaPP (sAbetaPPalpha) release via enhancing retention of AbetaPP on plasma membrane. In contrast, low [Mg2+]o enhanced CTFbeta accumulation and Abeta secretion, and reduced cell surface AbetaPP level. Varying [Mg2+]o did not alter protein contents of full length AbetaPP. However, decreased total intracellular magnesium level by magnesium deprivation over 24 hr impaired cell viability. Normal AbetaPP processing could be restored when magnesium was adjusted back to physiological concentration. These data demonstrate that AbetaPP processing can be modulated by magnesium and at high [Mg2+]o, AbetaPP processing favors the alpha-secretase cleavage pathway. Our findings suggest that supplementation of magnesium has a therapeutic potential for preventing AD.

Objective: The purpose of this meta-analysis was to evaluate the therapeutic effect of transcranial direct current stimulation (tDCS) on mild to moderate Alzheimer disease (AD) patients. Materials and Methods: PubMed, Embase, Web of Science, and Cochrane Library were searched until April 2018. The primary cognitive outcomes were extracted from included articles. A crude standardized mean difference with 95% CI was calculated by using fixed or random effect models. Results: Seven studies with 146 patients were included in this meta-analysis. The pooled result showed that tDCS significantly improved cognitive function of AD patients (standardized mean difference=0.37; 95% CI, 0.09-0.65; P=0.01). Subgroup analyses showed that: a single session of tDCS was significantly effective (P<0.05) whereas repeated sessions of tDCS was not lower current density (0.06 mA/cm2) (P>0.05) but not higher current density (0.08 mA/cm2) significantly improved cognitive performance; stimulating the temporal cortex (P<0.05) but not the left dorsal lateral prefrontal cortex significantly improved cognitive function of AD patients; and improved cognitive function occurred in the group with higher education (P<0.05) but not in the group with lower education. Conclusions: Current evidence suggests that tDCS has a beneficial effect in mild to moderate AD patients. We must be cautious about the results of subgroup analysis given small sample sizes, and further well-designed studies with larger sample size are required to verify these results.