Properties enhancement of PS nanocomposites through the POSS surfactants

Polyhedral oligomeric silsesquioxane (POSS)-clay hybrids of polystyrene are prepared by two organically modified clays using POSS-NH 2 and C 20 -POSS as intercalated agents. X-ray diffraction (XRD) studies show the formation of these POSS/clay/PS nanocomposites in all cases with the disappearance of the peaks corresponding to the basal spacing of MMT. Transmission electronic microscopy (TEM) was used to investigate the morphology of these nanocomposites and indicates that these nanocomposites are composed of a random dispersion of exfoliated clay platelets throughout the PS matrix. Incorporation of these exfoliated clay platelets into the PS matrix led to effectively increase in glass transition temperature (T g ), thermal decomposition temperature (T d ), and the maximum reduction in coefficient of thermal expansion (CTE) is ca. 40% for the C 20 -POSS/clay nanocomposite

Advanced age affects the outcome-predictive power of RIFLE classification in geriatric patients with acute kidney injury

The RIFLE (risk, injury, failure, loss, and end-stage) classification is widely used to gauge the severity of acute kidney injury, but its efficacy has not been formally tested in geriatric patients. To correct this we conducted a prospective observational study in a multicenter cohort of 3931 elderly patients (65 years of age or older) who developed acute kidney injury in accordance with the RIFLE creatinine criteria after major surgery. We studied the predictive power of the RIFLE classification for in-hospital mortality and investigated the potential interaction between age and RIFLE classification. In general, the survivors were significantly younger than the nonsurvivors and more likely to have hypertension. In patients 76 years of age and younger, RIFLE-R, -I, or -F classifications were significantly associated with increased hospital mortality in a stepwise manner. There was no significant difference, however, in hospital mortality in those over 76 years of age between patients with RIFLE-R and RIFLE-I, although RIFLE-F patients had significantly higher mortality than both groups. Thus, the less severe categorizations of acute kidney injury per RIFLE classification may not truly reflect the adverse impact on elderly patients

Late initiation of renal replacement therapy is associated with worse outcomes in acute kidney injury after major abdominal surgery

Introduction Abdominal surgery is probably associated with more likelihood to cause acute kidney injury (AKI). The aim of this study was to evaluate whether early or late start of renal replacement therapy (RRT) defined by simplified RIFLE (sRIFLE) classification in AKI patients after major abdominal surgery will affect outcome. Methods A multicenter prospective observational study based on the NSARF ( National Taiwan University Surgical ICU Associated Renal Failure) Study Group database. 98 patients (41 female, mean age 66.4 +/- 13.9 years) who underwent acute RRT according to local indications for post-major abdominal surgery AKI between 1 January, 2002 and 31 December, 2005 were enrolled The demographic data, comorbid diseases, types of surgery and RRT, as well as the indications for RRT were documented. The patients were divided into early dialysis (sRIFLE-0 or Risk) and late dialysis (LD, sRIFLE -Injury or Failure) groups. Then we measured and recorded patients' outcome including in-hospital mortality and RRT wean-off until 30 June, 2006. Results The in-hospital mortality was compared as endpoint. Fifty-seven patients (58.2%) died during hospitalization. LD (hazard ratio (HR) 1.846; P = 0.027), old age (HR 2.090; P = 0.010), cardiac failure (HR 4.620; P < 0.001), pre-RRT SOFA score (HR 1.152; P < 0.001) were independent indicators for in-hospital mortality. Conclusions The findings of this study support earlier initiation of acute RRT, and also underscore the importance of predicting prognoses of major abdominal surgical patients with AKI by using RIFLE classification

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

Properties Enhancement of PS Nanocomposites through the POSS Surfactants

Polyhedral oligomeric silsesquioxane (POSS)-clay hybrids of polystyrene are prepared by two organically modified clays using POSS-NH2 and C20-POSS as intercalated agents. X-ray diffraction (XRD) studies show the formation of these POSS/clay/PS nanocomposites in all cases with the disappearance of the peaks corresponding to the basal spacing of MMT. Transmission electronic microscopy (TEM) was used to investigate the morphology of these nanocomposites and indicates that these nanocomposites are composed of a random dispersion of exfoliated clay platelets throughout the PS matrix. Incorporation of these exfoliated clay platelets into the PS matrix led to effectively increase in glass transition temperature (Tg), thermal decomposition temperature (Td), and the maximum reduction in coefficient of thermal expansion (CTE) is ca. 40% for the C20-POSS/clay nanocomposite