Degradation of biomedical polydimethylsiloxanes during exposure to in vivo biofilm environment monitored by FE‐SEM,ATR‐FTIR,and MALDI‐TOF MS

Polymers used for biomedical purposes in medical devices are usually requested to be inert to degradation. This article describes that slow irreversible changes were observed in silicone surfaces exposed to in vivo biofilms even if silicone, in general, is supposed to have excellent long‐term properties. Tracheostomy tubes made of silicone rubber were exposed to in vivo biofilm environments in clinical tests for periods of 1, 3, and 6 months. The chemical degradation was monitored by MALDI‐TOF MS, ATR‐FTIR, and FE‐SEM. In addition, the physical changes were monitored by contact angle and hardness measurements. Cyclic polydimethylsiloxane (PDMS) was detected on the surfaces of new (unaged) silicones. On the surfaces of the in vivo samples new compounds, presumably linear methyl‐hydroxyl‐terminated PDMS, were detected in addition to cyclic PDMS. These compounds may be formed as a result of the hydrolysis of linear dimethyl terminated PDMS, which is also present in the silicone rubber. ATR‐FTIR spectroscopy confirmed that hydrolysis had indeed occurred during the in vivo exposure, since Si? OH groups were detected. Furthermore, significant changes in the topography were detected by FE‐SEM, indicating the initiation of degradation. No significant changes in the contact angle of the in vivo used samples were observed, but this information may be shielded by the fact that biofilm may remain on the surface, despite the thorough cleaning before the analysis. It is also possible that the surface hydrophobicity was recovered by the diffusion of linear low‐molecular‐weight compounds from the bulk. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Tissue reactions evoked by porous and plane surfaces made out of silicon and titanium

Square-shaped silicon or titanium implants with plane or porous surfaces surrounded by a rim of silicone were implanted in the rat abdominal wall for evaluation of the tissue response after one, six, or 12 weeks. Cell damage was identified as increased membrane permeability using fluorescence microscopy by injection of propidium iodide prior to the killing of the rats. Capsule thickness and immunohistochemical quantification of macrophages were used as a further measure of the foreign-body reaction. There were no significant differences in capsular cell densities for macrophages, total cells (macrophages, fibroblasts, and other cells), or necrotic cells at the different time points for the four surfaces studied. However, significant differences in the kinetics of the response were found between plane surfaces compared with porous ones. Both types of plane surfaces developed a significant increase in capsule thickness over time in contrast to the porous implants. Porous silicon displayed a significant decrease in total cells in the reactive capsule over time. Furthermore, porous silicon and titanium surfaces displayed a significant decrease in total cell numbers at the implant interface between six and 12 weeks. The present study demonstrated that implanted silicon elicited soft-tissue reactions comparable to that of titanium.     

Gender and Culture Differences in Emotion.

In this article, the authors report a secondary analysis on a cross-cultural dataset on gender differences in 6 emotions, collected in 37 countries all over the world. The aim was to test the universality of the gender-specific pattern found in studies with Western respondents, namely that men report more powerful emotions (e.g., anger), whereas women report more powerless emotions (e.g., sadness, fear). The authors expected the strength of these gender differences to depend on women's status and roles in their respective countries, as operationalized by the Gender Empowerment Measure (GEM; United Nations Development Programme Human Development Report 2002). Overall, the gender-specific pattern of women reporting to experience and express more powerless emotions and men more powerful emotions was replicated, and only some interactions with the GEM were found. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Safety as perceived by wheelchair-seated passengers in special transportation services

The aim of this study was to gain a better understanding of, and to help form a more complete picture of, the perceived safety of wheelchair-seated passengers using special transportation services (STS). A questionnaire was sent out and completed by 801 respondents in five Swedish regions. Additional information was acquired by means of 15 subsequent in-depth interviews. It was found that 5% reported personal incident-related injuries during the period that they had been eligible for STS. Injuries were most likely to occur during normal driving, but the passengers were also exposed to risks during boarding and alighting procedures. Nevertheless, 80% of the passengers were basically satisfied with the degree of safety. A large majority (97%) reported that they always use tie-down systems, and 78% always use safety belts. These results indicate that, despite general satisfaction with the STS system as such, malfunction of the existing safety equipment is a problem, since safety is especially critical for STS passengers-a vulnerable road-user group with few alternative travel modes. Therefore, there is a need for wheelchair tie-down and occupant restraint systems (WTORS) that are easier to handle by the operators and more suitable for the passengers and their wheelchairs. A low-floor vehicle concept might also reduce injury risks related to boarding and alighting procedures.     

Determination of dissociation constants for protein-ligand complexes by electrospray ionization mass spectrometry

A fully automated biophysical assay based on electrospray ionization mass spectrometry (ESI-MS) for the determination of the dissociation constants (KD) between soluble proteins and low molecular mass ligands is presented. The method can be applied to systems where the relative MS response of the protein and the protein-ligand complexes do not reflect relative concentrations. Thus, the employed approach enables the use of both electrostatically and nonpolar bound complexes. The dynamic range is wider than for most biological assays, which facilitates the process of establishing a structure-activity relationship. This fully automated ESI-MS assay is now routinely used for ligand screening. The entire procedure is described in detail using hGHbp, a 25-kDa extracellular soluble domain of the human growth hormone receptor, as a model protein.     

Physical and Swelling Properties of Spray‐Dried Powders made from Starch and Poly(vinyl alcohol)

The aim of this study was to investigate whether starch and poly(vinyl alcohol) could be compatible in a powder for coating. Free films of a mixture of the polymers were produced by casting and investigated with respect to their mechanical properties and moisture uptake. The moisture uptake was substantially higher when glycerol was added and the glycerol‐containing films had a lower failure stress under tension than the corresponding glycerol‐free films. At glycerol levels of 20 wt% or above, the glycerol content resulted in a high strain to failure. Dry powders with and without glycerol were made from the starch/poly(vinyl alcohol) solutions by spray drying. The powders were investigated by differential scanning calorimetry (DSC), to determine the degree of physical ageing or crystallinity. All powders showed a broad peak indicative of the melting of crystals at 100–150°C in the first scan, but this peak disappeared almost completely after rapid cooling. The glycerol‐free powder showed a small endothermic peak at about 45°C, indicating physical ageing of the powders during storage. Suspensions of the powders in a liquid plasticiser (glycerol or poly(ethylene glycol)) showed a sharp increase in storage modulus at a certain temperature, indicating the onset of swelling. The observed swelling meant that some of the powders are good candidates for plastisol coatings.     

Taking your place or matching your face: Two paths to empathic embarrassment.

Empathic responding may be elicited by different processes, depending on the available situational and affective cues. We investigated two such processes, perspective-taking and nonverbal mimicry. In Study 1, participants watched an embarrassed or unembarrassed confederate dancing to music while either remaining objective or engaging in perspective-taking. Both manipulations affected empathic embarrassment. Study 2 further examined the effects of targets' embarrassment displays and observers' prior experience with the situation upon spontaneous perspective-taking, expressive mimicry, and empathic embarrassment. Embarrassment displays increased mimicry, but also spontaneous perspective-taking and subsequent empathy. Prior experience moderated the effects of embarrassment displays on perspective-taking and empathy. Path analyses demonstrated that embarrassment displays exerted indirect effects on empathic embarrassment through both perspective-taking and mimicry. The results suggest that available affective and situational cues can activate different routes to empathy, and highlight the value of simultaneously investigating target- and observer-based sources of influence. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Chemical composition of enamel and dentine in primary teeth in children from Thailand exposed to lead

Enamel and dentine in teeth of children with high blood levels of lead were analyzed by means of secondary ion mass spectrometry (SIMS) and X-ray micro-analyses (XRMA) and compare with teeth from children with low blood levels of lead. The SIMS analysis revealed detectable levels of Pb in dentine close to the pulp. The XRMA analyses could not detect any lead. There were no differences found in lead level in enamel of high lead level exposed teeth from low level exposed. The results confirm that children with high blood levels of lead have an uptake of lead in dentine close to the pulp.