Internalization and cytotoxicity analysis of silicon-based microparticles in macrophages and embryos

Microchips can be fabricated, using semiconductor technologies, at microscopic level to be introduced into living cells for monitoring of intracellular parameters at a single cell level. As a first step towards intracellular chips development, silicon and polysilicon microparticles of controlled shape and dimensions were fabricated and introduced into human macrophages and mouse embryos by phagocytosis and microinjection, respectively. Microparticles showed to be non-cytotoxic for macrophages and were found to be localized mainly inside early endosomes, in tight association with endosomal membrane, and more rarely in acidic compartments. Embryos with microinjected microparticles developed normally to the blastocyst stage, confirming the non-cytotoxic effect of the particles. In view of these results silicon and polysilicon microparticles can serve as the frame for future intracellular chips development and this technology opens the possibility of real complex devices to be used as sensors or actuators inside living cells.     

Focus ion beam micromachined glass pipettes for cell microinjection

Cell handling is currently hindered by rudimentary-manufactured manipulators. Restrictive designs of glass pipettes and other micromanipulators limit functionality and often damage cells, ultimately resulting in lysis. We present a novel technique to design and mill conventional glass pipettes at specifically chosen angles and geometries. Focus ion beam milling by Ga+ ions yields extremely polished edges. Results from mouse embryo piercing correlate increased penetration rates with decreased pipette angle. Milled pipettes maintain structural integrity after repeated piercing. For the first time, the effects of unintentionally implanted Ga+ on embryo development are addressed. Optimum embryo development up to blastocyst stage after manipulation reveal little impact of residual implanted Ga+, suggesting biocompatibility and paving the way to introducing ion milling techniques in the biomedical device arena. The milling technique can be adequately tailored to specific applications and allows for mass production, presenting a promising avenue for future, increasingly demanding, cell handling.     

The 12-item World Health Organization Disability Assessment Schedule II (WHO-DAS II): a nonparametric item response analysis

Background  

Previous studies have analyzed the psychometric properties of the World Health Organization Disability Assessment Schedule II (WHO-DAS II) using classical omnibus measures of scale quality. These analyses are sample dependent and do not model item responses as a function of the underlying trait level. The main objective of this study was to examine the effectiveness of the WHO-DAS II items and their options in discriminating between changes in the underlying disability level by means of item response analyses. We also explored differential item functioning (DIF) in men and women.     

Microbial profile of placentas from Tanzanian mothers with adverse pregnancy outcomes and periodontitis

Aim

To investigate microbial profiles in placentas from a population of East African mothers with and without adverse pregnancy outcomes and with regard to their periodontal status.

Material and Methods

Thirty-six placentas from pregnant women from Tanzania were classified into three groups according to both pregnancy outcome and the mother's periodontal health. The microbial composition in each group was then compared using 16S rRNA metagenomics. Additionally, placenta specimens were analyzed histologically for chorioamnionitis by a single pathologist blinded to the clinical data.

Results

The greatest differences were observed in the group of mothers with periodontitis. The microbial load was low in all three groups of mothers. Periodontitis had a notable influence on the structure of the placental microbiota. Three phyla and 44 genera were associated with periodontitis, whereas only the Tenericutes phylum was associated with the adverse pregnancy variable. Streptococcaceae and Mycoplasmataceae families were associated with both periodontitis and adverse pregnancy outcomes. Finally, although the differences for chorioamnionitis were not significant, this intra-amniotic infection was more frequent in the placentas from mothers with periodontitis.

Conclusions

Our findings suggest that bacteria from the oral cavity may involve the feto-placental unit, and that periodontitis may be a modulating factor of the microbial community present in this niche.     

Validation of a French version of the Pure Procrastination Scale (PPS)

Procrastination is a widespread phenomenon that affects everyone's day-to-day life and interferes with the clinical treatment of several psychopathological states. To assess this construct, Steel (2010) developed the Pure Procrastination Scale (PPS), a short scale intended to capture the general notion of dysfunctional delay. The aim of the current study was to present a French version of this questionnaire. To this end, the 12 items of the PPS were translated into French and data were collected from an online survey in a sample of 245 French-speaking individuals from the general population. The results revealed that one item had problematic face validity; it was therefore removed. Exploratory and confirmatory analyses performed on the resulting 11-item version of the French PPS indicated that the scale was composed of two factors (“voluntary delay” and “observed delay”) depending on a common, higher-order construct (“general procrastination”). Good internal consistency and test–retest reliability were found. External validity was supported by specific relationships with measures of personality traits, impulsivity, and subjective well-being. The French PPS therefore presents satisfactory psychometric properties and may be considered a reliable and valid instrument for research, teaching and clinical practice.     

Voltammetry of heterogeneous labile metal–macromolecular systems for any ligand-to-metal ratio: Part I. Approximate voltammetric expressions for the limiting current to obtain complexation information

We present approximate expressions and rigorous numerical simulations corresponding to the voltammetric limiting currents of a titration experiment of a heterogeneous macromolecular ligand with a metal ion under fully labile conditions. We highlight the accuracy of an approximate expression based on a polynomial expansion of the limiting current in terms of the fraction of the bound metal concentration in the bulk solution. Values of the coefficients of the polynomial expansion for macromolecular complexation are provided. The accuracy of this polynomial expression for systems exhibiting different degrees of heterogeneity together with its easy computation, suggests its application in the finding of the bulk value of the bound metal concentration from the limiting current for a given pair of total ligand and metal concentrations. Thus, straightforward calculations lead to the binding curve which can then be interpreted using the standard methods.     

Sunscreen Use and Melanocytic Nevi in Children: A Systematic Review

Abstract: We conducted a systematic review of the association between melanocytic nevi (MN) in childhood and sunscreen use. A bibliographic search was conducted between November 2008 and January 2009 using the following key words on MEDLINE and EMBASE: child*, in combination with naevi, nevi, naevus, nevus and sunscreen, sun protection. We also used Medical Subject Headings [sunscreening agents], or [radiation protection] with [nevus, pigmented]. A first screening was done on title and abstract reading. Randomized trials and cohort and cross‐sectional studies analyzing the relationship between the use of sunscreen and MN in children were selected. Three reviewers abstracted data from each article. The three sets of results were compared for concordance and rereviewed if necessary. Fifteen articles were included (20,743 children). The studies were not consistent in terms of the ages of the children, MN count methods, or sunscreen use assessment. Owing to this heterogeneity, we were unable to pool the studies and conduct a meta‐analysis. Twelve studies did not report that the use of sunscreen had a protective effect against MN development. Three studies reported a lower MN count when sunscreen was applied. This systematic review underlines the methodologic differences between studies. Eight of 15 studies reported a positive association between sunscreen application and MN count. Differences in MN counts, overexposure to sun, and inadequate sunscreen application on fair‐skinned children could explain the disparity in the results. There is still no evidence of a protective effect of sunscreen against MN development in children.