Publishing negative results: the problem of publication bias

A Classification Bias and an Exclusion Bias Jointly Overinflated the Estimation of Publication Biases in Bilingualism Research

A publication bias has been argued to affect the fate of results in bilingualism research. It was repeatedly suggested that studies presenting evidence for bilingual advantages are more likely to be published compared to studies that do not report results in favor of the bilingual advantage hypothesis. This work goes back to the original claim and re-examines both the dataset and the classification of the studies that were employed. We find that the exclusion of published works such as doctoral dissertations, book chapters, and conference proceedings from the original dataset significantly inflated the presumed publication bias. Moreover, the estimation of the publication bias was affected by a classification bias that uses a mega-category that consists of both null and negative outcomes. Yet finding evidence for a bilingual disadvantage is not synonymous with obtaining a result indistinguishable from zero. Consequently, grouping together null and negative findings in a mega-category has various ramifications, not only for the estimation of the presumed publication bias but also for the field's ability to appreciate the insofar hidden correlations between bilingual advantages and disadvantages. Tracking biases that inflate scientific results is important, but it is not enough. The next step is recognizing the nested Matryoshka doll effect of bias-within-bias, and this entails raising awareness for one's own bias blind spots in science.

On the value of preprints: An early career researcher perspective

Peer-reviewed journal publication is the main means for academic researchers in the life sciences to create a permanent public record of their work. These publications are also the de facto currency for career progress, with a strong link between journal brand recognition and perceived value. The current peer-review process can lead to long delays between submission and publication, with cycles of rejection, revision, and resubmission causing redundant peer review. This situation creates unique challenges for early career researchers (ECRs), who rely heavily on timely publication of their work to gain recognition for their efforts. Today, ECRs face a changing academic landscape, including the increased interdisciplinarity of life sciences research, expansion of the researcher population, and consequent shifts in employer and funding demands. The publication of preprints, publicly available scientific manuscripts posted on dedicated preprint servers prior to journal-managed peer review, can play a key role in addressing these ECR challenges. Preprinting benefits include rapid dissemination of academic work, open access, establishing priority or concurrence, receiving feedback, and facilitating collaborations. Although there is a growing appreciation for and adoption of preprints, a minority of all articles in life sciences and medicine are preprinted. The current low rate of preprint submissions in life sciences and ECR concerns regarding preprinting need to be addressed. We provide a perspective from an interdisciplinary group of ECRs on the value of preprints and advocate their wide adoption to advance knowledge and facilitate career development.

Survivin overexpression is potentially associated with pituitary adenoma invasiveness

Background and objective

Survivin is an inhibitor of apoptosis. Its role in guiding the treatment of neoplasms, making diagnosis and predicting prognosis has been reported. However, there is little information on the implications and uses of survivin in predicting pituitary adenoma (PA) invasiveness. Existing information is unclear and controversial. We thus conducted this meta-analysis to explore whether the surviving expression levels in invasive PAs (IPA) and regular PAs are different or not. We considered both non-secreting and secreting tumors together.

Methods

A global search strategy was systematically applied among five databases including Cochrane Library, Embase, PubMed, Web of Science, and Chinese National Knowledge Infrastructure (CNKI) up to June 18th, 2017. With a specially designed form including PAs’ invasive features, etc., data was collected. The included studies should present the data representing the surviving levels in IPA groups and regular PA groups, respectively. Differences were expressed as standard mean differences (SMDs) or odds ratios (ORs) with 95% confidence interval (CI). To estimate the heterogeneities, I² test, Cochran's Q-test and Galbr figure were all conducted. A sensitivity-analysis and potential-publication bias were also performed.

Results

In the present meta-analysis, 9 studies containing 489 patients were included. Seven studies with dichotomous-data showed that survivin over-expression in PA tissue was closely associated with a high invasive tendency (OR 6.226, 95% CI 3.970, 9.765; P<0.001), but 2 continuous-data studies revealed that there was no significant association (SMD −5.043, 95% CI-10.965, 0.878; p=0.095). A sensitivity-analysis suggested a statistically stable result. We did not find publication bias.

Conclusion

We suggest that survivin overexpression is potentially associated with PA invasiveness. More research based on medical big data is needed to confirm this finding.

Is CD147 a New Biomarker Reflecting Histological Malignancy of Gliomas?

CD147 belongs to immunoglobulin superfamily and can stimulate the surrounding fibroblasts to secret matrix metalloproteinases (MMPs). Studies showed that when compared with their normal counterparts, CD47 expression level increased in lung carcinoma tissue, breast cancer tissue, and bladder cancer tissue. They increase in line with a tumor's malignant progression, invasiveness, and metastasis. However, the precise implications and utility of the presence of CD147 in the WHO grading system for gliomas have rarely been reported; in addition, the signal transduction pathways regarding CD147 remain unclear and controversial. Thus, in performing a meta-analysis, it is essential to reach a reliable conclusion. The related literatures were incorporated into the present meta-analysis after careful assessment, and odds ratios (ORs) with 95 % confidence intervals (95 % CIs) were calculated. Heterogeneity evaluation was estimated. Ten studies involving 615 patients were found to be eligible, nine of which were conducted in China and the remaining one in Japan. Analysis of eight studies involving dichotomous data revealed that CD147 overexpression in glioma tissue was related to higher WHO grading (III + IV; OR, 9.900; 95 % CI, 5.943, 16.491; P = 0.000) closely, whereas analysis of three studies of continuous data type indicated that there were no statistical associations (standard mean difference, -1.894; 95 % CI, -4.081, 0.293; P = 0.090). In accordance with funnel plot, Egger test, and Begg test, there was no publication bias. Considering that the continuous data make up only a small proportion of the overall analysis, we believe that our study indicates that CD147 overexpression is potentially related to higher WHO grade. Certainly, more data compiled based on evidence-based medicine are required to further support this conclusion.

CD105 Over-expression Is Associated with Higher WHO Grades for Gliomas

CD105 is an ancillary receptor of transforming growth factor beta (TGF-β), which has been suggested as a suitable biomarker for cancer-related angiogenesis and neovascularization (Nassiri et al. in Anticancer Res 31:2283-2290, 2011). However, the clinical significance of CD105 in WHO grade was rarely reported and the effects of CD105 signal transduction pathway on gliomas remain controversial and unclear. To get a convincing conclusion, performing a meta-analysis is essential. Relevant literature studies were included via careful evaluation, and standard mean difference (SMD) and hazard ratio (HR) with 95 % confidence intervals (95 % CIs) was calculated. We also made funnel plots to test the heterogeneity. In the present meta-analysis, a total of 11 eligible literatures involving 796 patients were incorporated. They were all conducted in China, revealing that CD105 overexpression in glioma tissues was strongly linked to high WHO grading (III+IV) (SMD -1.785, 95 % CI -2.133, -1.437; p = 0.000). No significant associations between CD105 and age (SMD -0.505, 95 % CI -1.054, 0.043; p = 0. 071), CD105 and gender (SMD 0.101, 95 % CI -0.103, 0.305; p = 0.333), and CD105 and tumor size (SMD -0.433, 95 % CI -1.326, 0.459; p = 0. 341) were detected. Besides, CD105 expression was closely associated with glioma patients' 3-year overall survival (OS; n = 2; HR = 4.357, 95 % CI 1.412, 7.303; p = 0.004). On the basis of Begg's and Egger's test or funnel plot, no publication bias was detected. In a nutshell, this meta-analysis demonstrated that CD105 overexpression correlates to higher WHO grade and poor survival and could be indicated as a helpful prognostic and diagnostic marker, or a useful therapy target.

CD34 Over-Expression is Associated With Gliomas' Higher WHO Grade

CD34 is a transmembrane phosphoglycoprotein that was first identified on hematopoietic stem and progenitor cells. CD34 is known as an optimum marker for microvascular density studies and it is positively stained in pathological and physiologic vessels. The use of CD34 for the prognosis, diagnosis, and treatment of neoplasms has been increasingly discussed. The implications and utilities of CD34 in WHO grades of gliomas and its prognosis have been reported rarely. Also, the WHO grades and prognosis researches remains unclear and controversial. A meta-analysis is the best choice for drawing a convincing conclusion. Several databases were searched. We carefully assess the relevant articles and standard mean differences (SMDs) with 95% confidence intervals (95% CIs) were estimated in terms of the relationship between CD34 expression levels with gliomas' WHO grades, patients' ages and gender. We used the Galbraith figure, the I test, and Cochran Q test to evaluate the heterogeneity of the included studies. A sensitivity analysis was conducted to assess the pooled results' stability. A Contour-enhanced funnel plot evaluation was made to assess potential publication bias. Ethics review and approval was not necessary because the meta-analysis did not involve any direct human trials or animal experiments. There were 12 eligible studies, including 684 patients who were considered in the present meta-analysis. All of them were conducted in China. CD34 overexpression in glioma tissues was associated closely, according to the pooled SMD, with higher WHO grade (III + IV) (SMD -1.503, 95% CI -1.685 to -1.321; P = 0.000). There were no significant associations between CD34 and age (SMD -0.223, 95% CI -0.602 to 0.156; P = 0.248) and CD34 and gender (SMD -0.059, 95% CI -0.439, 0.321; P = 0.761). No publication bias was detected according to Contour-enhanced funnel plot. Our results suggested that CD34 overexpression is associated with higher WHO grades of gliomas. CD34 may serve as a potential diagnostic and prognostic marker, or it could be a useful therapy target.

Does Tenascin have Clinical Implications in Pathological Grade of Glioma Patients?: A Systematic Meta-Analysis

Tenascin (TN) is an extracellular oligomeric glycoprotein that participates in the adhesion of cells to extracellular matrixc (ECM). Studies have shown that the expression levels of TN are upregulated in a variety of cancers, including colon cancer, lung cancer, brain tumor, and breast cancer. However, the implications and utilities of TN in clinical grading and prognosis of glioma patients were seldom reported and the effects of its pathway are still unclear and controversial. Thus, it is essential to carry out a meta-analysis to draw a convincing conclusion.A literature search was carried out up to April 2015. Data was collected using a purpose-designed form including glioma's WHO grade, etc. Differences were expressed as odds ratios (ORs) or standard mean differences (SMDs) with 95% confidence intervals (CIs). Galbr figure, Cochran's Q test, and I test were all performed to judge the heterogeneity between included studies. To examine the stability of the pooled results, a sensitivity analysis was performed. Potential publication bias was assessed by visual inspection of funnel plot. As this meta-analysis, as a systematic review, does not involve animal experiments or direct human trials, there is no need to conduct special ethic review and the ethical approval is not necessary.In this meta-analysis, 8 eligible studies involving 456 patients were incorporated. Six studies with dichotomous data revealed TN overexpression in glioma tissues and/or surrounding neoplastic vessels was closely associated with high WHO grade (III + IV) (odds ratio 3.398, 95% confidence interval 1.933, 5.974; P = 0.000); three continuous data studies showed there were close statistical associations between TN and WHO grade (SMD -2.114, 95% CI -2.580, -1.649; P = 0.000) too. Sensitivity analysis indicated a statistically robust result. No publication bias was revealed.Our meta-analysis suggests that TN expression is potentially associated with higher WHO grade of gliomas. More evidences on the basis of the evidence-based medicine are needed to prove it.

A call for transparent reporting to optimize the predictive value of preclinical research

The US National Institute of Neurological Disorders and Stroke convened major stakeholders in June 2012 to discuss how to improve the methodological reporting of animal studies in grant applications and publications. The main workshop recommendation is that at a minimum studies should report on sample-size estimation, whether and how animals were randomized, whether investigators were blind to the treatment, and the handling of data. We recognize that achieving a meaningful improvement in the quality of reporting will require a concerted effort by investigators, reviewers, funding agencies and journal editors. Requiring better reporting of animal studies will raise awareness of the importance of rigorous study design to accelerate scientific progress.

Metallothionein and the biology of aging

Metallothionein (MT) is a low molecular weight protein with anti-apoptotic properties that has been demonstrated to scavenge free radicals in vitro. MT has not been extensively investigated within the context of aging biology. The purpose of this review, therefore, is to discuss findings on MT that are relevant to basic aging mechanisms and to draw attention to the possible role of MT in pro-longevity interventions. MT is one of just a handful of proteins that, when overexpressed, has been demonstrated to increase mouse lifespan. MT also protects against development of obesity in mice provided a high fat diet as well as diet-induced oxidative stress damage. Abundance of MT is responsive to caloric restriction (CR) and inhibition of the insulin/insulin-like signaling (IIS) pathway, and elevated MT gene expression has been observed in tissues from fasted and CR-fed mice, long-lived dwarf mice, worms maintained under CR conditions, and long-lived daf-2 mutant worms. The dysregulation of MT in these systems is likely to have tissue-specific effects on aging outcomes. Further investigation will therefore be needed to understand how MT contributes to the response of invertebrates and mice to CR and the endocrine mutations studied by aging researchers.