Measurement of the Optical Constants of Sand Samples Using Ellipsometry on Sand-Adhesive Composites.

In order to model the propagation of light through a sand cloud, it is critical to have accurate data for the optical constants of the sand particles that comprise it. The same holds true for modeling propagation through particles of any type suspended in a medium. Few methods exist, however, to measure these quantities with high accuracy. In this paper, a characterization method based on spectroscopic ellipsometry (SE) that can be applied to a particulate material is presented. In this method, a polished disc of an adhesive compound is prepared, and its optical constants are measured. Next, a mixture of the adhesive and a sand sample is prepared and processed into a polished disc, and SE is performed. By treating the mixture as a Bruggeman effective medium, the optical constants of the particulate material are extracted. For verification of the proposed method, it is first applied to pure silica powder, demonstrating good agreement between measured optical constants and literature values. It is then applied to Arizona road dust, a standard reference material, as well as real desert sand samples. The resulting optical constant data is input into a rigorous scattering model to predict extinction coefficients for various types of sand. Modeling results are compared to spectroscopic measurements on static sand samples, demonstrating good agreement between predicted and measured spectral properties including the presence of a Christiansen feature near a wavelength of 8 µm.

Induced Pluripotent Stem Cell-Derived Podocyte-Like Cells as Models for Assessing Mechanisms Underlying Heritable Disease Phenotype: Initial Studies Using Two Alport Syndrome Patient Lines Indicate Impaired Potassium Channel Activity.

Renal podocyte survival depends upon the dynamic regulation of a complex cell architecture that links the glomerular basement membrane to integrins, ion channels, and receptors. Alport syndrome is a heritable chronic kidney disease where mutations in α3, α4, or α5 collagen genes promote podocyte death. In rodent models of renal failure, activation of the calcium-sensing receptor (CaSR) can protect podocytes from stress-related death. In this study, we assessed CaSR function in podocyte-like cells derived from induced-pluripotent stem cells from two patients with Alport Syndrome (AS1 & AS2) and a renal disease free individual [normal human mesangial cell (NHMC)], as well as a human immortalized podocyte-like (HIP) cell line. Extracellular calcium elicited concentration-dependent elevations of intracellular calcium in all podocyte-like cells. NHMC and HIP, but not AS1 or AS2 podocyte-like cells, also showed acute reductions in intracellular calcium prior to elevation. In NHMC podocyte-like cells this acute reduction was blocked by the large-conductance potassium channel (KCNMA1) inhibitors iberiotoxin (10 nM) and tetraethylammonium (5 mM), as well as the focal adhesion kinase inhibitor PF562271 (N-methyl-N-(3-((2-(2-oxo-2,3-dihydro-1H-indol-5-ylamino)-5-trifluoromethyl-pyrimidin-4-ylamino)-methyl)-pyridin-2-yl)-methanesulfonamide, 10 nM). Quantitative polymerase chain reaction (qPCR) and immunolabeling showed the presence of KCNMA1 transcript and protein in all podocyte-like cells tested. Cultivation of AS1 podocytes on decellularized plates of NHMC podocyte-like cells partially restored acute reductions in intracellular calcium in response to extracellular calcium. We conclude that the AS patient-derived podocyte-like cells used in this study showed dysfunctional integrin signaling and potassium channel function, which may contribute to podocyte death seen in Alport syndrome.

Can C-reactive protein predict the severity of a post-operative complication after elective resection of colorectal cancer?

AIMS: To explore if post-operative day 3 C-reactive protein (CRP), the ratio of pre-operative to day 3 white cell count (WCC) and platelet count can be used to predict the risk of post-operative complication and stratify the severity of complications as defined by the Clavien-Dindo classification. METHODS: Data was obtained retrospectively on 127 patients who had elective bowel resection for malignancy between 2011 and 2013. Baseline demographics and clinical details were obtained including pre-operative and day 3 WCC and platelets and day 3 CRP. Ratio of pre-operative to day 3 WCC and platelets was calculated. Outcome measures were if a complication occurred (death included) and complication as defined by the Clavien-Dindo clasification. Mann-Whitney U test and Kruskal-Wallis were used to test for significance. RESULTS: Of 127 patients, 57 % (n = 73) were male with a total median age of 72 and the commonest histology result T3N0 (40.6 %, n = 52). CRP was found to predict a complication (p < 0.0005) and the severity of complication as per the Clavien-Dindo classification (p < 0.0005). Day 3 CRP over 285 suggested a life-threatening complication (Clavien-Dindo score 4). There was no statistical significance between the ratio of WCC and platelets to any of the outcome measures. CONCLUSIONS: WCC, platelets and CRP are routinely performed in the post-operative period. Previous research has shown CRP to be a good predictor of a complication. This paper has shown that day 3 CRP can not only predict but can also stratify the severity of post-operative complications.

Very low quality of life after acute stroke: data from the Efficacy of Nitric Oxide in Stroke trial.

BACKGROUND AND PURPOSE: Health-related quality of life, a key outcome after stroke, plays a role in the analysis of treatment cost-effectiveness. Some measures of health-related quality of life allow for a quality of life worse than death; the characteristics of such patients have not been well described. METHODS: Data from the Efficacy of Nitric Oxide in Stroke (ENOS) trial were used to explore health-related quality of life after stroke. The EuroQol questionnaire (EQ-5D) was performed at day 90, and a health utility score (HUS) was calculated. HUS was defined as follows: poor-good HUS>0, death HUS=0, and very poor HUS<0. The characteristics and outcomes of patients with HUS<0 were then explored. RESULTS: Of the 2569 patients, 303 (11.8%) died, and of the 2238 with quality of life data available, of whom 724 (32.3%) were completed by a proxy, 1959 (87.5%) had an HUS>0 and 279 (12.5%) had an HUS<0. Patients with HUS<0 were more likely to be older, women, have severe stroke, have proxy responders, and be institutionalized. Dominant hemisphere strokes were more likely to have proxy responders but not HUS<0. HUS was strongly correlated with dependency (modified Rankin Scale, r=-0.78) and disability (Barthel index, r=0.84) and moderately correlated with mood (Zung depression score, r=-0.59) and baseline severity (r=0.51). All but 1 patient with modified Rankin Scale of 5 had an HUS<0. CONCLUSIONS: Very low health-related quality of life is relatively common after stroke, particularly in patients with mobility problems or who are dependent on help for usual activities, and is related to poor functional outcome measures. CLINICAL TRIAL REGISTRATION URL: http://www.controlled-trials.com/. Unique identifier: ISRCTN99414122.

Testing for differential item functioning within the EQ-5D.

We test for the presence of differential item functioning (DIF) in the EQ-5D health-related quality-of-life instrument, using data from a large clinical trial in acute stroke (ISRCTN 99414122). DIF occurs when subjects in different subsets of a sample respond differently to items in a measurement instrument, despite possessing the same latent traits. The data comprised 1462 patient records. We analyzed DIF specifically with respect to responses obtained from different geographical regions and responses obtained from proxies as opposed to the patients themselves. We mapped clinical outcome measures (scores from the modified Rankin Scale, the Barthel Index, and the Zung Depression scale) onto EQ-5D index scores and included dummy variables for proxy responses and for region of treatment (United Kingdom, Asia, rest of world). We predicted the level of problem severity reported on each of the EQ-5D's five constituent dimensions from the clinical measures and the dummy variables. For given clinical characteristics, proxies were more likely to report health problems than were the patients themselves, although the divergences were not sufficiently large to result in any significant difference in mean index scores between patient and proxy reports. However, the distributions of reported levels of problems for similar clinical states diverged significantly by region, and these translated into different index scores. The mean index score for UK responses was significantly higher than the mean index scores from Asia and the rest of the world.