An ERP study of hemispheric differences in perceptual representations of language reveals meaning attribution in the right hemisphere and constituents of the N400-effect.

Recent findings have revealed that the right hemisphere (RH) is uniquely involved in integrating perceptual information from linguistic input to simulate a mental model of that input. We extend on these findings by testing whether meaning is generated from such models. Participants (N = 37) heard auditory passages describing the visuospatial arrangement of elements into a perceptual representation of a familiar object, then judged whether a laterally-presented target word matched the object. We found a central N400-effect for left visual-field targets, suggesting that meaning was also accessible to the RH. There was no statistical difference for right visual-field targets. Principle component analysis of the data revealed that the N400-effect was driven by positive components. Consequently, the results suggest that i) RH contributions to language comprehension include integrative and perceptual processes that enable overall meaning to be generated from representations of discourse, and ii) positive ERP components may produce N400-effects.

Determinants of Neonatal Vitamin D Levels as Measured on Neonatal Dried Blood Spot Samples.

BACKGROUND: Vitamin D deficiency is linked to adverse childhood health outcomes, yet data on the distribution and quantifiable determinants of neonatal 25-hydroxyvitamin D3 (25OHD) concentration, a vitamin D biomarker, are limited. OBJECTIVE: Our aim was to identify determinants of neonatal 25OHD concentration, measured using neonatal dried blood spots (DBS). METHODS: A total of 259 ethnically diverse children aged 0-16 years born in Victoria, Australia, were recruited. Data included maternal sun exposure, skin type, 25OHD concentration on stored neonatal DBS, and genotypes at the target genes. Associations were investigated using multiple linear regression models. RESULTS: The median 25OHD concentration was 29.2 nmol/l (IQR 18.0-47.4). Measured 25OHD was <50 nmol/l in almost half of the neonatal sample. Ambient ultraviolet radiation (UVR) 6 weeks before birth was the strongest predictor of neonatal 25OHD, accounting for 23% of its variation. A further 10% was explained by infant genetic variants at GC (rs2282679), the gene encoding the vitamin D binding protein, and DHCR7 (rs12785878), a gene required for synthesis of 7-dehydrocholesterol, a precursor to 25OHD. DBS age explained 7%, and patterns of maternal sun exposure and clothing choices accounted for 4%. A child's skin colour was strongly associated with GC gene variants and not independent of these variants in predicting 25OHD. The final model explained 43% of the total variance in neonatal 25OHD concentration. CONCLUSION: Maternal lifestyle factors and infant genetic variants predict neonatal 25OHD levels; the importance of maternal UVR exposure in late pregnancy is highlighted.

The relationship between intravenous infusate colonisation and fluid container hang time.

AIMS: To examine the level of microbial colonisation in intravenous fluids after 24 hours of use in an acute care setting to determine the necessity of changing infusate bags on a time-related basis. BACKGROUND: Catheter-related bloodstream infections are a serious and life-threatening complication of intravascular devices. Colonised intravenous fluids are one potential source of infection; however, there is little published literature on incidence rates and few recent studies. Routine intravenous fluid replacement has been advocated as an infection control method, but the effectiveness of this is unknown and the optimal duration for infusate use remains uncertain. DESIGN: Cross-sectional study over 18 months in a 257-bed teaching hospital. METHODS: Infusate specimens (n = 264) were obtained from crystalloid fluids that had been used for 24 hours or more. Microbiological culture and sensitivity testing was performed and infusate-related bloodstream infection (IRBSI) rates were recorded. Sample testing of previously unopened intravenous solutions acted as a control. RESULTS: The infusate colonisation rate was 0.4%, or 0.09 per 1000 infusion hours. The only isolated organism was coagulase-negative Staphylococcus. Infusions had been in use for 24-185 hours (1-8 days). There was no difference in median duration of use for colonised (35.0 hours) and sterile (34.0 hours) specimens (Mann-Whitney test, p = 0.99). There were no cases of IRBSI. CONCLUSION: The incidence of intravenous fluid colonisation and the risk of related bloodstream infection are low even after several days of infusate use. Current practice appears to successfully maintain the sterility of intravenous fluids. RELEVANCE TO CLINICAL PRACTICE: Routine replacement of intravenous fluids continues in many settings, often 24 hourly, in the belief that this prevents infection. We found no relationship between duration of use and colonisation and routine replacement may be unnecessary. Further research is needed to investigate the effectiveness of routinely replacing intravenous fluids at set time points to prevent colonisation and infection.