When one depends on the other: reporting of interaction in case-control and cohort studies

BACKGROUND: Interaction refers to the situation in which the effect of 1 exposure on an outcome differs across strata of another exposure. We did a survey of epidemiologic studies published in leading journals to examine how interaction is assessed and reported. METHODS: We selected 150 case-control and 75 cohort studies published between May 2001 and May 2007 in leading general medicine, epidemiology, and clinical specialist journals. Two reviewers independently extracted data on study characteristics. RESULTS: Of the 225 studies, 138 (61%) addressed interaction. Among these, 25 (18%) presented no data or only a P value or a statement of statistical significance; 40 (29%) presented stratum-specific effect estimates but no meaningful comparison of these estimates; and 58 (42%) presented stratum-specific estimates and appropriate tests for interaction. Fifteen articles (11%) presented the individual effects of both exposures and also their joint effect or a product term, providing sufficient information to interpret interaction on an additive and multiplicative scale. Reporting was poorest in articles published in clinical specialist articles and most adequate in articles published in general medicine journals, with epidemiology journals in an intermediate position. CONCLUSIONS: A majority of articles reporting cohort and case-control studies address possible interactions between exposures. However, in about half of these, the information provided was unsatisfactory, and only 1 in 10 studies reported data that allowed readers to interpret interaction effects on an additive and multiplicative scale.

Phosphorylation of serine 4642 in the C-terminus of plectin by MNK2 and PKA modulates its interaction with intermediate filaments

Plectin is a versatile cytolinker of the plakin family conferring cell resilience to mechanical stress in stratified epithelia and muscles. It acts as a critical organizer of the cytoskeletal system by tethering various intermediate filament (IF) networks through its C-terminal IF-binding domain (IFBD). Mutations affecting the IFBD cause devastating human diseases. Here, we show that serine 4642, which is located in the extreme C-terminus of plectin, is phosphorylated in different cell lines. Phosphorylation of S4642 decreased the ability of plectin IFBD to associate with various IFs, as assessed by immunofluorescence microscopy and cell fractionation studies, as well as in yeast two-hybrid assays. Plectin phosphorylated at S4642 was reduced at sites of IF network anchorage along cell-substrate contacts in both skin and cultured keratinocytes. Treatment of SK-MEL-2 and HeLa cells with okadaic acid increased plectin S4642 phosphorylation, suggesting that protein phosphatase 2A dephosphorylates this residue. Moreover, plectin S4642 phosphorylation was enhanced after cell treatment with EGF, phorbol ester, sorbitol and 8-bromo-cyclic AMP, as well as during wound healing and protease-mediated cell detachment. Using selective protein kinase inhibitors, we identified two different kinases that modulate the phosphorylation of plectin S4642 in HeLa cells: MNK2, which is downstream of the ERK1/2-dependent MAPK cascade, and PKA. Our study indicates that phosphorylation of S4642 has an important regulatory role in the interaction of plectin with IFs and identifies a novel link between MNK2 and the cytoskeleton.

Surface charge of polymer coated SPIONs influences the serum protein adsorption, colloidal stability and subsequent cell interaction in vitro

It is known that the nanoparticle-cell interaction strongly depends on the physicochemical properties of the investigated particles. In addition, medium density and viscosity influence the colloidal behaviour of nanoparticles. Here, we show how nanoparticle-protein interactions are related to the particular physicochemical characteristics of the particles, such as their colloidal stability, and how this significantly influences the subsequent nanoparticle-cell interaction in vitro. Therefore, different surface charged superparamagnetic iron oxide nanoparticles were synthesized and characterized. Similar adsorbed protein profiles were identified following incubation in supplemented cell culture media, although cellular uptake varied significantly between the different particles. However, positively charged nanoparticles displayed a significantly lower colloidal stability than neutral and negatively charged particles while showing higher non-sedimentation driven cell-internalization in vitro without any significant cytotoxic effects. The results of this study strongly indicate therefore that an understanding of the aggregation state of NPs in biological fluids is crucial in regards to their biological interaction(s).

An investigation into the factors that encourage learner participation in a large group medical classroom

BACKGROUND: Effective lectures often incorporate activities that encourage learner participation. A challenge for educators is how to facilitate this in the large group lecture setting. This study investigates the individual student characteristics involved in encouraging (or dissuading) learners to interact, ask questions, and make comments in class. METHODS: Students enrolled in a Doctor of Veterinary Medicine program at Ross University School of Veterinary Medicine, St Kitts, were invited to complete a questionnaire canvassing their participation in the large group classroom. Data from the questionnaire were analyzed using Excel (Microsoft, Redmond, WA, USA) and the R software environment (http://www.r-project.org/). RESULTS: One hundred and ninety-two students completed the questionnaire (response rate, 85.7%). The results showed statistically significant differences between male and female students when asked to self-report their level of participation (P=0.011) and their confidence to participate (P<0.001) in class. No statistically significant difference was identified between different age groups of students (P=0.594). Student responses reflected that an "aversion to public speaking" acted as the main deterrent to participating during a lecture. Female participants were 3.56 times more likely to report a fear of public speaking than male participants (odds ratio 3.56, 95% confidence interval 1.28-12.33, P=0.01). Students also reported "smaller sizes of class and small group activities" and "other students participating" as factors that made it easier for them to participate during a lecture. CONCLUSION: In this study, sex likely played a role in learner participation in the large group veterinary classroom. Male students were more likely to participate in class and reported feeling more confident to participate than female students. Female students in this study commonly identified aversion to public speaking as a factor which held them back from participating in the large group lecture setting. These are important findings for veterinary and medical educators aiming to improve learner participation in the classroom. Potential ways of addressing this challenge include addition of small group activities and audience response systems during lectures, and inclusion of training interventions in public speaking at an early stage of veterinary and medical curricula.

Interaction of corroding iron with bentonite in the ABM1 experiment at Äspö, Sweden: A microscopic approach

Bentonite and iron metals are common materials proposed for use in deep-seated geological repositories for radioactive waste. The inevitable corrosion of iron leads to interaction processes with the clay which may affect the sealing properties of the bentonite backfill. The objective of the present study was to improve our understanding of this process by studying the interface between iron and compacted bentonite in a geological repository-type setting. Samples of MX-80 bentonite samples which had been exposed to an iron source and elevated temperatures (up to 115ºC) for 2.5 y in an in situ experiment (termed ABM1) at the Äspö Hard Rock Laboratory, Sweden, were investigated by microscopic means, including scanning electron microscopy, μ-Raman spectroscopy, spatially resolved X-ray diffraction, and X-ray fluorescence. The corrosion process led to the formation of a ~100 mm thick corrosion layer containing siderite, magnetite, some goethite, and lepidocrocite mixed with the montmorillonitic clay. Most of the corroded Fe occurred within a 10 mm-thick clay layer adjacent to the corrosion layer. An average corrosion depth of the steel of 22–35 μm and an average Fe2+ diffusivity of 1–26×10–13 m2/s were estimated based on the properties of the Fe-enriched clay layer. In that layer, the corrosion-derived Fe occurred predominantly in the clay matrix. The nature of this Fe could not be identified. No indications of clay transformation or newly formed clay phases were found. A slight enrichment of Mg close to the Fe–clay contact was observed. The formation of anhydrite and gypsum, and the dissolution of some SiO<inf>2inf> resulting from the temperature gradient in the in situ test, were also identified. © 2014, Clay Minerals Society. All right reserved.