Pruritus: Is there a grain of salty truth?

Hemodialysis patients characteristically suffer from a range of unpleasant symptoms. Uremic pruritus effects close to half of the chronic kidney disease population, reducing quality of life and associated with increased mortality. Its pathophysiology though is poorly understood; currently deployed therapeutic approaches are ineffective. Excessive levels of skin and soft tissue sodium accumulate in dialysis patients, producing a range of biological consequences, including inflammation. We report an index case of a hemodialysis patient with debilitating pruritus and extreme levels of tissue sodium, measured with Sodium-23 magnetic resonance imaging. Both the tissue sodium loading and pruritus responded fully to initiation of expanded hemodialysis therapy with a recently introduced medium cutoff dialysis membrane-based dialyzer.     

Are drivers aware of sleepiness and increasing crash risk while driving?

Drivers are advised to take breaks when they feel too tired to drive, but there is question over whether they are able to detect increasing fatigue and sleepiness sufficiently to decide when to take a break. The aim of this study was to investigate the extent to which drivers have access to cognitive information about their current state of sleepiness, likelihood of falling asleep, and the implications for driving performance and the likelihood of crashing. Ninety drivers were recruited to do a 2 h drive in a driving simulator. They were divided into three groups: one made ratings of their sleepiness, likelihood of falling asleep and likelihood of crashing over the next few minutes at prompts occurring at 200 s intervals throughout the drive, the second rated sleepiness and likelihood of falling asleep at prompts but pressed a button on the steering wheel at any time if they felt they were near to crashing and the third made no ratings and only used a button-press if they felt a crash was likely. Fatigue and sleepiness was encouraged by monotonous driving conditions, an imposed shorter than usual sleep on the night before and by afternoon testing. Drivers who reported that they were possibly, likely or very likely to fall asleep in the next few minutes, were more than four times more likely to crash subsequently. Those who rated themselves as sleepy or likely to fall asleep had a more than 9-fold increase in the hazards of a centerline crossing compared to those who rated themselves as alert. The research shows clearly that drivers can detect changes in their levels of sleepiness sufficiently to make a safe decision to stop driving due to sleepiness. Therefore, road safety policy needs to move from reminding drivers of the signs of sleepiness and focus on encouraging drivers to respond to obvious indicators of fatigue and sleepiness and consequent increased crash risk.     

Are international co-publications an indicator for quality of scientific research?

This article deals with the role of internationally co-authored papers (co-publications). Specifically, we compare, within a data-set of German research units, citation and co-publication indicators as a proxy for the unobserved quality dimension of scientific research. In that course we will also deal with the question whether both citations and co-publications are considerably related. Our results suggest that, although there is a strong partial correlation between citations and co-publications within a multivariate setting, we cannot use reasonably normalised co-publication indicators as an alternative proxy for quality. Thus, concerning quality assessment, there remains a primer on citation analysis.     

Overweight children: Are they at increased risk for severe injury in motor vehicle collisions?

Background

Obesity is an epidemic in the United States. The relationship between traumatic injury and obesity in children is not well-studied. We hypothesized that overweight children suffer more severe injuries, different distributions of injuries and improper use of restraints in motor vehicle collisions.

Methods

We conducted a secondary analysis of the CIREN database of motor vehicle collisions of subjects 2-17 years old. Overweight was defined as a BMI percentile for age >85%. Significant injury was an Injury Severity Score (ISS) >15 or an Abbreviated Injury Scale (AIS) score greater than one. Further analysis looked at injuries classified as head, trunk, or extremities and appropriateness of restraints. Odds ratios compared the overweight to lean groups.

Results

335 subjects met inclusion criteria with 35.5% of cases being overweight. For significant injury, overweight cases had an odds ratio of 1.2 [95% CI: 0.8-1.9]. Analysis by AIS for overall significant injury and to specific body regions also did not show any significant associations. Overweight versus lean subjects had an odds ratio of 1.3 [95% CI: 0.8-2.1] for improper use of restraints.

Conclusions

We found no significant relationship between pediatric injury severity, distribution of injuries, or restraint use and being overweight. Limitations of this study were the small sample size in this database and the large number of unrestrained subjects.     

Is there a golden age in publication activity?—an analysis of age-related scholarly performance across all scientific disciplines

Scientometrics - We examined whether the publication characteristics of various scientific disciplines exhibit age-related trends. Our analysis was based on two large data sets comprising all major...     

Are there pre-Quaternary geological analogues for a future greenhouse warming?

Given the inherent uncertainties in predicting how climate and environments will respond to anthropogenic emissions of greenhouse gases, it would be beneficial to society if science could identify geological analogues to the human race's current grand climate experiment. This has been a focus of the geological and palaeoclimate communities over the last 30 years, with many scientific papers claiming that intervals in Earth history can be used as an analogue for future climate change. Using a coupled ocean-atmosphere modelling approach, we test this assertion for the most probable pre-Quaternary candidates of the last 100 million years: the Mid- and Late Cretaceous, the Palaeocene-Eocene Thermal Maximum (PETM), the Early Eocene, as well as warm intervals within the Miocene and Pliocene epochs. These intervals fail as true direct analogues since they either represent equilibrium climate states to a long-term CO(2) forcing--whereas anthropogenic emissions of greenhouse gases provide a progressive (transient) forcing on climate--or the sensitivity of the climate system itself to CO(2) was different. While no close geological analogue exists, past warm intervals in Earth history provide a unique opportunity to investigate processes that operated during warm (high CO(2)) climate states. Palaeoclimate and environmental reconstruction/modelling are facilitating the assessment and calculation of the response of global temperatures to increasing CO(2) concentrations in the longer term (multiple centuries); this is now referred to as the Earth System Sensitivity, which is critical in identifying CO(2) thresholds in the atmosphere that must not be crossed to avoid dangerous levels of climate change in the long term. Palaeoclimatology also provides a unique and independent way to evaluate the qualities of climate and Earth system models used to predict future climate.     

Benchmarking international scientific excellence: Are highly cited research papers an appropriate frame of reference?

This paper introduces a citation-based "systems approach" for analyzing the various institutional and cognitive dimensions of scientific excellence within national research systems. The methodology, covering several aggregate levels, focuses on the most highly cited research papers in the international journal literature. The distribution of these papers across institutions and disciplines enables objective comparisons their (possible) international-level scientific excellence. By way of example, we present key results from a recent series of analyses of the research system in the Netherlands in the mid 1990s, focussing on the performance of the universities across the various major scientific disciplines within the context of the entire system"s scientific performance. Special attention is paid to the contribution in the world"s top 1% and top 10% most highly cited research papers. The findings indicate that these high performance papers provide a useful analytical framework - both in terms of transparency, cognitive and institutional differentiation, as well as its scope for domestic and international comparisons - providing new indicators for identifying "world class" scientific excellence at the aggregate level. The average citation scores of these academic "Centres of Scientific Excellence" appear to be an inadequate predictor of their production of highly cited papers. However, further critical reflection and in-depth validation studies are needed to establish the true potential of this approach for science policy analyses and evaluation of research performance. This revised version was published online in August 2006 with corrections to the Cover Date.     

Heating of metals at a free surface by laser irradiation—an electron kinetic theory approach

Application of Fourier theory to heat conduction due to laser irradiation at high power intensities (i.e. 10¹⁰ w/m²) gives errors of the order of 30 percent at the upper end of the temperature rise time. This is caused by the assumptions made in the Fourier theory, since the heat flux through a given plane depends on the electron energy distribution through the material. The scale of distance required to examine the problem, the material can no longer be considered as being homogenous continuum and when the power intensities of interest are concerned, the higher order terms in the heat transfer equation becomes important. Therefore, the problem requires to be examined in the quantum field. Application of electron kinetic theory to the problem enhance the solution within an accuracy greater than 90 percent. The present theory introduces a new model for the conduction mechanism.     

Is there an association between intradialytic hypotension and serum magnesium changes?

Intradialytic hypotension (IDH) is the most common complication of hemodialysis (HD). The aim of this study was to investigate the significance of intradialytic changes of serum magnesium (sMg) and its relation to IDH. We considered 58 patients undergoing HD. Serum magnesium was measured at start, after 2 hours, and at the end of the HD sessions. Total sMg concentration corrected for albumin was according to Krolles proposed formula. Blood pressure was measured every 30 min. Data were analyzed by SPSS.15. A P value of less than 0.05 was considered as significant. Occurrence of IDH among HD patients was 27.6% (16/58). Serum magnesium decreased significantly during HD session (P<0.05). Comparing corrected sMg in IDH group with non-IDH group showed that: corrected sMg was 0.66 ± 0.14 mmol/L vs. 0.84 ± 0.26 mmol/L at the start of dialysis (P=0.43), 0.62 ± 0.17 mmol/L vs. 0.74 ± 0.23 mmol/L (P=0.04) at 2 hours, and 0.61 ± 0.12 mmol/L vs. 0.72 ± 0.22 mmol/L (P=0.03) at the end of dialysis. Intradialytic hypotension episodes were significantly related to a decrease in sMg during dialysis (P=0.02). There was a significant decrease in sMg levels during dialysis. Intradialytic hypotension was significantly related to lowered sMg levels during dialysis.     

In Australia are people born in other countries at higher risk of road trauma than locally born people?

This study examined whether people born in other countries had higher rates of death and hospitalization due to road crashes than people born in Australia. Data on deaths that occurred in the whole of Australia between 1994 and 1997 and hospitalizations that occurred in the state of New South Wales, Australia, between 1 July 1995 and 30 June 1997 due to road crashes were analyzed. The rates of death and hospitalization, adjusted for age and area of residence, were calculated using population data from the 1996 Australian census. The study categorized people born in other countries according to the language (English speaking, non-English speaking) and the road convention (left-hand side, right-hand side) of their country of birth. Australia has the left-hand side driving convention. The study found that drivers born in other countries had rates of death or hospitalization due to road trauma equal to or below those of Australian born drivers. In contrast, pedestrians born in other countries, especially older pedestrians had higher rates of death and hospitalization due to road crashes. Pedestrians aged 60 years or more born in non-English speaking countries where traffic travels on the right-hand side of the road had risks about twice those of Australian born pedestrians in the same age group.     

Existence of Pseudogap at the Transition Temperature of an Electron-Doped Copper–Oxide Superconductor

We present the scanning tunnelling spectroscopy (STS) studies of the energy gap (Δ) at the Fermi surface of electron-doped high-temperature (high-T _c ) cuprate superconductor Pr_0.88 LaCe _0.12 CuO _4?δ , which is commonly known as PLCCO. We found that the energy gap does not vanish at the transition temperature (T _c ). Moreover, it was observed that gap-like features are present at some locations of the sample at temperatures above T _c . The energy gap with magnitude is found consistent with d-wave symmetry. We also found the value of the ratio 2Δ/K _B T _c higher than 7, which puts electron-doped cuprates in strong coupling regime.     

Oral intake during hemodialysis: Is there an association with intradialytic hypotension?

Oral intake (OI) of food and fluid has been associated with hypotension during hemodialysis (HD). Trials evaluating this relationship are small. The objective of this study was to quantify OI and to examine its association with hypotension during HD. This is a cross-sectional retrospective chart review study of 3 consecutive HD runs (dialysate iCa=1.25 mmol/L) in 126 stable HD patients (n=378). For each run, the calculation for OI=total ultrafiltration-(net weight loss+IV fluids given). Hypotension was defined as a systolic blood pressure of <100 mmHg at any point during the run. The mean age of the patients was 60.9 years, 38.2% were female, 30.2% had diabetes mellitus, and the majority were Caucasian. The mean (SD) OI was 0.27 (0.352) L/run, range -1.061 to 1.901 L/run, with a normal distribution. In bivariate analysis, there was no correlation of OI with systolic blood pressure, diastolic blood pressure, or mean blood pressure (BP), and the mean OI did not differ among runs with hypotension (n=78) compared with uncomplicated runs (p=0.93). Oral intake was not predictive of hypotension in a multiple logistic regression model controlling for vintage, age, sex, BP medications, coronary disease, dialysis day and shift, diabetes mellitus, s-Ca, Na and ultrafiltration profiles, and dialysis temperature, even when the analysis was restricted to runs where the patients reached the prescribed dry weight within 0.1 kg. The results of this study suggest that the mean OI during dialysis is just over 0.25 kg, with some patients consuming several kilograms. The clinical significance of OI is uncertain. We did not find an association between OI and hypotension. It is likely that this association was confounded by failure to achieve the prescribed dry weight in a proportion of patients with a high OI, as well as interventions implemented in response to hypotension in previous runs. For example, patients with previous episodes of low BP are advised to limit OI, are prescribed profiles, and so on. There may be other deleterious effects of high OI including hypertension and cardiac disease. The generalizability of the results of this largely Caucasian study population is a recognized limitation. Further prospective and blinded studies are needed to examine the association between OI and hypotension, the long-term clinical consequences of OI, and to define thresholds for recommended OI during dialysis.     

Properties of Iron Oxide Nanoparticles Synthesized at?Different?Temperatures

Iron oxide nanoparticles were synthesized by co-precipitation in air atmosphere at different temperatures and their structural and magnetic properties were investigated. The mean particle sizes of iron oxide nanoparticles were calculated from the X-ray diffraction (XRD) patterns using the Scherrer equation. Fourier transform infrared spectroscopy analysis exhibited the vibration bands at 563 cm^?1 and 620 cm^?1 confirming the formation of Fe₃O₄ and ??-Fe₂O₃, respectively. Morphological observation was made by a transmission electron microscope and the particle size of iron oxide nanoparticles was found to be around 9 nm which is consistent with the particle size calculated according to the XRD patterns. It was observed that the intensity of the peaks in the patterns and crystallinity increased as the temperature increased. Magnetization curves showed zero coercivities indicating that the samples are superparamagnetic.     

Particle‐Based Optical Sensing of Intracellular Ions at the Example of Calcium – What Are the Experimental Pitfalls?

Colloidal particles with fluorescence read‐out are commonly used as sensors for the quantitative determination of ions. Calcium, for example, is a biologically highly relevant ion in signaling, and thus knowledge of its spatio‐temporal distribution inside cells would offer important experimental data. However, the use of particle‐based intracellular sensors for ion detection is not straightforward. Important associated problems involve delivery and intracellular location of particle‐based fluorophores, crosstalk of the fluorescence read‐out with pH, and spectral overlap of the emission spectra of different fluorophores. These potential problems are outlined and discussed here with selected experimental examples. Potential solutions are discussed and form a guideline for particle‐based intracellular imaging of ions.