Statistical multiplicity in systematic reviews of anaesthesia interventions: a quantification and comparison between Cochrane and non-Cochrane reviews

Background

Systematic reviews with meta-analyses often contain many statistical tests. This multiplicity may increase the risk of type I error. Few attempts have been made to address the problem of statistical multiplicity in systematic reviews. Before the implications are properly considered, the size of the issue deserves clarification. Because of the emphasis on bias evaluation and because of the editorial processes involved, Cochrane reviews may contain more multiplicity than their non-Cochrane counterparts. This study measured the quantity of statistical multiplicity present in a population of systematic reviews and aimed to assess whether this quantity is different in Cochrane and non-Cochrane reviews.

Methods/Principal Findings

We selected all the systematic reviews published by the Cochrane Anaesthesia Review Group containing a meta-analysis and matched them with comparable non-Cochrane reviews. We counted the number of statistical tests done in each systematic review. The median number of tests overall was 10 (interquartile range (IQR) 6 to 18). The median was 12 in Cochrane and 8 in non-Cochrane reviews (difference in medians 4 (95% confidence interval (CI) 2.0–19.0). The proportion that used an assessment of risk of bias as a reason for doing extra analyses was 42% in Cochrane and 28% in non-Cochrane reviews (difference in proportions 14% (95% CI −8 to 36). The issue of multiplicity was addressed in 6% of all the reviews.

Conclusion/Significance

Statistical multiplicity in systematic reviews requires attention. We found more multiplicity in Cochrane reviews than in non-Cochrane reviews. Many of the reasons for the increase in multiplicity may well represent improved methodological approaches and greater transparency, but multiplicity may also cause an increased risk of spurious conclusions. Few systematic reviews, whether Cochrane or non-Cochrane, address the issue of multiplicity.     

Detection of Campylobacter concisus and other Campylobacter species in colonic biopsies from adults with ulcerative colitis

Introduction

The critical role of bacteria in the pathogenesis of ulcerative colitis (UC) is well recognized, but an individual causative microorganism has not been singled out so far. Campylobacter concisus and other non-jejuni species of Campylobacter have been implicated as putative aetiological agents in inflammatory bowel disease in children, but such studies have not been addressed in adults. This study investigated the prevalence of Campylobacter species in colonic biopsy samples from adults with UC and healthy controls.

Methods

Adult patients who were undergoing diagnostic colonoscopy were recruited for the study, which included 69 patients with histologically proven UC and 65 healthy controls. DNA was extracted from the biopsy samples and subjected to Campylobacter genus specific and Campylobacter concisus specific polymerase chain reaction and sequencing.

Results

Detection of all Campylobacter DNA utilising genus specific primers was significantly higher in cases of UC, with a prevalence of 73.9% (51/69) compared to 23.1% (15/65) in controls (p = 0.0001). Nested PCR for C. concisus DNA was positive in 33.3% (23/69) of biopsy samples from subjects with UC, which was significantly higher than the prevalence rate of 10.8% (7/65) from controls (p = 0.0019). Sequencing of the remaining Campylobacter positive samples revealed that Campylobacter ureolyticus was positive in 21.7% (15/69) of samples from UC subjects as opposed to 3.1% (2/65) in controls (p = 0.0013). Mixed Campylobacter species were more common in UC patients, 20.3% (14/69) as compared to controls 4.6% (3/65) (p = 0.0084).

Conclusion

The higher prevalence of Campylobacter genus and more specifically C. concisus and C. ureolyticus in biopsy samples from adults with UC suggests these genera of bacteria may be involved in the chronic inflammation that is characteristically seen in UC. To the best of our knowledge this is the first report of this association of C. concisus and C. ureolyticus with UC in adults.     

Proteolytic activity in enzymatic extracts from Carica papaya L. cv. Maradol harvest by-products

Proteolytic activity and the cysteine protease profile were determined for enzymatic extracts (EE) from Carica papaya L. cv. Maradol harvest by-products (stems, unripe fruit, petioles and leaves). The proportion of each by-product type in the sampled plantation was calculated. Polypeptide bands were identified by SDS–PAGE for each EE and molecular weight calculated for the cysteine proteases. Leaf and fruit tissue had the highest protein contents of the by-products. Leaf tissue also produced the highest total EE yield. All the SDS–PAGE gels for the EE’s exhibited an approximately 23 kDa band probably corresponding to papain. The zymography profiles of the EE’s were similar, with bands at approximately >202.8, 76.8, 55.4 and 46.5 kDa. The fruit EE had the highest specific proteolytic activity and the leaf EE the lowest. Fruit and stem by-products are the most promising for proteolytic enzyme extraction.     

Conformation of a synthetic antigenic peptide from HIV-1 p24 protein induced by ionic micelles

We studied the interaction of the peptide AAMQMLKETINEEAAEWDRVHPVHAGPIA from the HIV-1 p24 protein in the presence of SDS (anionic) and CTABr (cationic) micelles at pH 7.0 by circular dichroism, fluorescence, and electron spin resonance (ESR). The micelles induced secondary structure as well as a blue shift in the tryptophan fluorescence emission, indicating an interaction between the peptide and the micelles. However, different contents of secondary structure elements were found when the peptide interacts with SDS or CTABr micelles. Steady-state anisotropy indicates a constraint on the rotational mobility of the tryptophan residue of the peptide upon interaction with micelles. ESR studies pointed to different locations for the peptide in either micelle. Our results suggested that at least part of the peptide might be located at the hydrophobic core of the CTABr micelles, probably at the C-terminal region, while it is more inserted into the SDS micelles.     

GPCR screening via ERK 1/2: a novel platform for screening G protein-coupled receptors

Discovery of novel agonists and antagonists for G protein-coupled receptors (GPCRs) relies heavily on cell-based assays because determination of functional consequences of receptor engagement is often desirable. Currently, there are several key parameters measured to achieve this, including mobilization of intracellular Ca2+ and formation of cyclic adenosine monophosphate or inositol triphosphate. However, no single assay platform is suitable for all situations, and all of the assays have limitations. The authors have developed a new high-throughput homogeneous assay platform for GPCR discovery as an alternative to current assays, which employs detection of phosphorylation of the key signaling molecule p42/44 MAP kinase (ERK 1/2). The authors show that ERK 1/2 is consistently activated in cells stimulated by Gq-coupled GPCRs and provides a new high-throughput platform for screening GPCR drug candidates. The activation of ERK 1/2 in Gq-coupled GPCR systems generates comparable pharmacological data for receptor agonist and antagonist data obtained by other GPCR activation measurement techniques.     

Exotic species of freshwater decapod crustaceans in the state of São Paulo,Brazil: records and possible causes of their introduction

Based on recent surveys of the freshwater decapod fauna, distributional data of five exotic species of freshwater decapod crustaceans for the hydrographic basins of the state of São Paulo are presented, as part of a large initiative for a comprehensive survey of the state’s biodiversity (BIOTA-FAPESP Program). These species are the North American crayfish Procambarus clarkii (Girard) (Cambaridae), the crab Dilocarcinus pagei Stimpson (Trichodactylidae) from the Amazon and Paraguay/lower Paraná River Basins, and the palaemonid shrimps Macrobrachium rosenbergii (De Man), from the Indo-Pacific region, Macrobrachium amazonicum (Heller) and Macrobrachium jelskii (Miers), both from the Orinoco, Amazon and the Paraguay/lower Paraná River Basins. Possible modes by which their introduction might have occurred are commented upon and potential consequences are discussed.     

Temporal variation of the population structure and genetic diversity of Farfantepenaeus notialis assessed by allozyme loci

Population genetic studies carried out on penaeid shrimps have disclosed different patterns of population subdivision, revealing new aspects of shrimp biology as well as the effects of historical contingency molding those patterns. However, the stability of observed allele frequencies over time still remains untested. The objective of this article is to show the analysis of the temporal variation of allozymes in a shrimp species inhabiting Cuba which proves that the genetic structure of this species could significantly change in time. The study involves four populations of Farfantepenaeus notialis sampled in a period of 8 years. The significant statistics obtained from partitions observed in 1995 were not detected in 2003 (as suggested by AMOVA and F(ST)), whereas temporal genetic differentiation and heterozygosity became highly significant. The results strongly suggest that the effect of migrations could be the cause for the loss of F. notialis genetic structure in 2003. It is therefore imperative to call attention on the vulnerability of these populations when facing unstable environmental and habitat conditions.     

Regulation of microfilament organization by Kaposi sarcoma-associated herpes virus-cyclin.CDK6 phosphorylation of caldesmon

Kaposi sarcoma-associated herpes virus (KSHV) encodes a D-like cyclin (K-cyclin) that is thought to contribute to the viral oncogenicity. K-cyclin activates cellular cyclin-dependent kinases (CDK) 4 and 6, generating enzymes with a substrate selectivity deviant from CDK4 and CDK6 activated by D-type cyclins, suggesting different biochemical and biological functions. Here we report the identification of the actin- and calmodulin-binding protein caldesmon (CALD1) as a novel K-cyclin.CDK substrate, which is not phosphorylated by D.CDK. CALD1 plays a central role in the regulation of microfilament organization, consequently controlling cell shape, adhesion, cytokinesis and motility. K-cyclin.CDK6 specifically phosphorylates four Ser/Thr sites in the human CALD1 carboxyl terminus, abolishing CALD1 binding to its effector protein, actin, and its regulator protein, calmodulin. CALD1 is hyperphosphorylated in cells following K-cyclin expression and in KSHV-transformed lymphoma cells. Moreover, expression of exogenous K-cyclin results in microfilament loss and changes in cell morphology; both effects are reliant on CDK catalysis and can be reversed by the expression of a phosphorylation defective CALD1. Together, these data strongly suggest that K-cyclin expression modulates the activity of caldesmon and through this the microfilament functions in cells. These results establish a novel link between KSHV infection and the regulation of the actin cytoskeleton.     

Manipulation of allergen-induced airway remodeling by treatment with anti-TGF-beta antibody: effect on the Smad signaling pathway

Airway inflammation and remodeling are important pathophysiologic features of chronic asthma. Previously, we have developed a mouse model of prolonged allergen challenge which exhibits many characteristics of chronic asthma such as goblet cell hyperplasia and subepithelial collagen deposition, in association with an increase in lung expression of the profibrotic mediator, TGF-beta. The aim of this study was to determine the effects of blockade of TGF-beta on the development of airway inflammation and remodeling using our murine model of prolonged allergen challenge. Importantly anti-TGF-beta Ab was administered therapeutically, with dosing starting after the onset of established eosinophilic airway inflammation. Therapeutic treatment of mice with anti-TGF-beta Ab significantly reduced peribronchiolar extracellular matrix deposition, airway smooth muscle cell proliferation, and mucus production in the lung without affecting established airway inflammation and Th2 cytokine production. Thus, our data suggest that it might be possible to uncouple airway inflammation and remodeling during prolonged allergen challenge. In addition, anti-TGF-beta Ab treatment was shown to regulate active TGF-beta signaling in situ with a reduction in the expression of phospho-Smad 2 and the concomitant up-regulation of Smad 7 in lung sections. Therefore, this is the first report to suggest that anti-TGF-beta Ab treatment prevents the progression of airway remodeling following allergen challenge even when given in a therapeutic mode. Moreover, the molecular mechanism behind this effect may involve regulation of active TGF-beta signaling.