Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

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In vivo brain sampling using a microextraction probe reveals metabolic changes in rodents after deep brain stimulation

Brain metabolomics is an emerging field that complements the more traditional approaches of neuroscience. However, typical brain metabolomics workflows require that animals be sacrificed and tend to involve tedious sample preparation steps. Microdialysis, the standard technique to study brain metabolites in vivo, is encumbered by significant limitations -in the analysis of hydrophobic metabolites, which are prone to adsorption losses on microdialysis equipment. An alternative sampling method suitable for in vivo brain studies is solid-phase microextraction (SPME). In SPME, a small probe coated with a biocompatible polymer is employed to extract/enrich analytes from biological matrices. In this work, we report the use of SPME and liquid chromatography-mass spectrometry for untargeted in vivo analysis of rodent's brains after deep brain stimulation (DBS). First, metabolite changes occurring in brain hippocampi after application of 3 h of DBS to the animals' prefrontal cortex were monitored with the proposed approach. As SPME allows for nonlethal sampling, the same group of animals was sampled again after 8 days of daily DBS therapy. After acute DBS, we detected changes in a broad range of metabolites, including the amino acid citrulline, which may reflect changes in nitric oxide production, as well as various phospho- and glycosphingolipids. Measurements conducted after chronic DBS showed a decrease in hippocampal corticosterone, indicating that DBS may have a regulatory effect in the hypothalamic-pituitary-adrenal axis. Our findings demonstrate the potential of in vivo SPME as a tool of scientific and clinical interest capable of revealing changes in a wide range of metabolites in brain tissue

The Stop Number Minimization Problem: Complexity and Polyhedral Analysis

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Chitosan-Immobilized Pumice for the Removal of As(V) from Waters

A novel sorbent, chitosan-immobilized pumice, has been prepared for the sorption of As(V) from waters prior to its determination by hydride generation atomic absorption spectrometry. The success of the immobilization has been checked with such characterization techniques as scanning electron microscopy, thermal gravimetric analysis, and elemental analysis. Points of zero charge of the sorbents were determined with potentiometric mass titration. Batch-type equilibration studies have shown that the novel sorbent can be employed at a wide pH range resulting in quantitative sorption (>90 %) at pH 3.0-7.0 and greater than 70 % sorption at pH >8.0. These results demonstrate the advantage of immobilizing chitosan onto pumice, because, under the same conditions, pumice displays <20 % sorption toward As(V), whereas chitosan gives approximately 90%sorption only at pH 3.0. The validity of the method was verified through the analysis of ultrapure, bottled drinking, and tap water samples spiked with arsenate; the respective sorption percentages of 93.2 (±0.7), 89.0 (±1.0), and 80.9 (±1.3) were obtained by batch-type equilibration. Arsenic sorption was also examined in the presence of common interfering ions resulting in competing effects of PO3- 4 and NO- 3on As(V) adsorption