Biopsy-based calibration of T2* magnetic resonance for estimation of liver iron concentration and comparison with R2 Ferriscan.

BACKGROUND: There is a need to standardise non-invasive measurements of liver iron concentrations (LIC) so clear inferences can be drawn about body iron levels that are associated with hepatic and extra-hepatic complications of iron overload. Since the first demonstration of an inverse relationship between biopsy LIC and liver magnetic resonance (MR) using a proof-of-concept T2* sequence, MR technology has advanced dramatically with a shorter minimum echo-time, closer inter-echo spacing and constant repetition time. These important advances allow more accurate calculation of liver T2* especially in patients with high LIC. METHODS: Here, we used an optimised liver T2* sequence calibrated against 50 liver biopsy samples on 25 patients with transfusional haemosiderosis using ordinary least squares linear regression, and assessed the method reproducibility in 96 scans over an LIC range up to 42 mg/g dry weight (dw) using Bland-Altman plots. Using mixed model linear regression we compared the new T2*-LIC with R2-LIC (Ferriscan) on 92 scans in 54 patients with transfusional haemosiderosis and examined method agreement using Bland-Altman approach. RESULTS: Strong linear correlation between ln(T2*) and ln(LIC) led to the calibration equation LIC = 31.94(T2*)-1.014. This yielded LIC values approximately 2.2 times higher than the proof-of-concept T2* method. Comparing this new T2*-LIC with the R2-LIC (Ferriscan) technique in 92 scans, we observed a close relationship between the two methods for values up to 10 mg/g dw, however the method agreement was poor. CONCLUSIONS: New calibration of T2* against liver biopsy estimates LIC in a reproducible way, correcting the proof-of-concept calibration by 2.2 times. Due to poor agreement, both methods should be used separately to diagnose or rule out liver iron overload in patients with increased ferritin

Non-Visual Effects of Light on Melatonin, Alertness and Cognitive Performance: Can Blue-Enriched Light Keep Us Alert?

Light exposure can cascade numerous effects on the human circadian process via the non-imaging forming system, whose spectral relevance is highest in the short-wavelength range. Here we investigated if commercially available compact fluorescent lamps with different colour temperatures can impact on alertness and cognitive performance

A survey for variable young stars with small telescopes: VI — Analysis of the outbursting Be stars NSW284, Gaia19eyy, and VES263

This paper is one in a series reporting results from small telescope observations of variable young stars. Here, we study the repeating outbursts of three likely Be stars based on long-term optical, near-infrared, and mid-infrared photometry for all three objects, along with follow-up spectra for two of the three. The sources are characterised as rare, truly regularly outbursting Be stars. We interpret the photometric data within a framework for modelling light curve morphology, and find that the models correctly predict the burst shapes, including their larger amplitudes and later peaks towards longer wavelengths. We are thus able to infer the start and end times of mass loading into the circumstellar disks of these stars. The disk sizes are typically 3 – 6 times the areas of the central star. The disk temperatures are ∼ 40 %, and the disk luminosities are ∼ 10 % of those of the central Be star, respectively. The available spectroscopy is consistent with inside-out evolution of the disk. Higher excitation lines have larger velocity widths in their double-horned shaped emission profiles. Our observations and analysis support the decretion disk model for outbursting Be stars

Hydroxyurea treatment decreases glomerular hyperfiltration in children with sickle cell anemia

Glomerular hyperfiltration and microalbuminuria/proteinuria are early manifestations of sickle nephropathy. The effects of hydroxyurea therapy on these renal manifestations of sickle cell anemia (SCA) are not well defined. Our objective was to investigate the effects of hydroxyurea on glomerular filtration rate (GFR) measured by 99mTc-DTPA clearance, and on microalbuminuria/proteinuria in children with SCA. Hydroxyurea study of long-term effects (HUSTLE) is a prospective study (NCT00305175) with the goal of describing the long-term cellular, molecular, and clinical effects of hydroxyurea therapy in SCA. Glomerular filtration rate, urine microalbumin, and serum cystatin C were measured before initiating hydroxyurea therapy and then repeated after 3 years. Baseline and Year 3 values for HUSTLE subjects were compared using the Wilcoxon Signed Rank test. Associations between continuous variables were evaluated using Spearman correlation coefficient. Twenty-three children with SCA (median age 7.5 years, range, 2.5-14.0 years) received hydroxyurea at maximum tolerated dose (MTD, 24.4 ± 4.5 mg/kg/day, range, 15.3-30.6 mg/kg/day). After 3 years of treatment, GFR measured by 99mTc-DTPA decreased significantly from 167 ± 46 mL/min/1.73 m2 to 145 ± 27 mL/min/1.73 m2 (P = 0.016). This decrease in GFR was significantly associated with increase in fetal hemoglobin (P = 0.042) and decrease in lactate dehydrogenase levels (P = 0.035). Urine microalbumin and cystatin C levels did not change significantly. Hydroxyurea at MTD is associated with a decrease in hyperfiltration in young children with SCA. © 2012 Wiley Periodicals, Inc

Edouard Mallet's early and almost forgotten study of the average height of Genevan conscripts in 1835

In 1835, Edouard Mallet published a notable but today nearly forgotten study of the average height of Genevan conscripts. His individual data included 3 029 conscripts born between 1805 and 1814, examined and measured between 1826 and 1835. Mallet’s work was only the third auxological study to be based on a large sample of individual conscript data, the other two being those of Louis-René Villermé and Adolphe Quetelet, but as far as we know Mallet's was the first to note the law of normal distribution. Like Villermé and Quetelet, Mallet explained urban/rural and international differences in average height strictly in terms of environmental and economic determinants. In the recent past, references to Mallet’s work have been rare, and limited to citations of his computed averages. We postulate that Mallet and his study deserve greater consideration for their contribution to the field of anthropometric history than they have yet received