Prevalence and risk factors of cataract after chemotherapy with or without central nervous system irradiation for childhood acute lymphoblastic leukaemia: an LEA study.

Corticosteroid and central nervous system (CNS) irradiation can induce cataract in childhood lymphoblastic leukaemia survivors. Few prospective studies with systematic ophthalmological evaluation have been published. Cataract was prospectively assessed by serial slip lamp tests in 517 patients. All had acute lymphoblastic leukaemia, all had been treated by chemotherapy with or without CNS irradiation, and none had received haematopoietic stem cell transplantation. Median ages at last evaluation and follow-up duration from leukaemia diagnosis were 16·8 and 10·9 years, respectively. Cataract was observed in 21/517 patients (4·1%). Cumulative incidence was 4·5 ± 1·2% at 15 years and reached 26 ± 8·1% at 25 years. CNS irradiation was the only risk factor: prevalence was 11·1% in patients who had received irradiation and 2·8% in those who did not. We did not detect any steroid dose effect: cumulative dose was 5133 and 5190 mg/m(2) in patients with and without cataract, respectively. Cataract occurrence did not significantly impact quality of life. We conclude that, in the range of steroid dose reported here, the cataract risk proves very low 15 years after treatment without CNS irradiation but an even more prolonged follow-up is required because of potential very late occurrence.

Symptomatic osteonecrosis in childhood leukemia survivors: prevalence, risk factors and impact on quality of life in adulthood.

Corticosteroid can induce osteonecrosis in children with leukemia. Few studies have been designed to assess the influence of a wide range of cumulative steroid dose on this side effect. Prevalence, risk factors of symptomatic osteonecrosis and its impact on adults' Quality of Life were assessed in 943 patients enrolled in the French "Leucémies de l'Enfant et de l'Adolescent" (LEA) cohort of childhood leukemia survivors. During each medical visit, data on previous osteonecrosis diagnosis were retrospectively collected. Patients without a history but with suggestive symptoms were investigated with magnetic resonance imaging. The total steroid dose in equivalent of prednisone was calculated for each patient and its effect on osteonecrosis occurrence was studied in multivariate models. Cumulative incidence was 1.4% after chemotherapy alone versus 6.8% after transplantation (P<0.001). A higher cumulative steroid dose, age over ten years at diagnosis, and treatment with transplantation significantly increased the risk of osteonecrosis. A higher post-transplant steroid dose and age over ten years at time of transplantation were significant factors in the transplanted group. With patients grouped according to steroid dose quartile, cumulative incidence of osteonecrosis reached 3.8% in the chemotherapy group for a dose beyond 5835 mg/m(2) and 23.8% after transplantation for a post-transplant dose higher than 2055 mg/m(2). Mean physical composite score of Quality of Life was 44.3 in patients with osteonecrosis versus 54.8% in patients without (P<0.001). We conclude that total and post-transplant cumulative steroid dose may predict the risk of osteonecrosis, a rare late effect with a strong negative impact on physical domains of Quality of Life.

Cross-laboratory experimental study of non-noble-metal electrocatalysts for the oxygen reduction reaction.

Nine non-noble-metal catalysts (NNMCs) from five different laboratories were investigated for the catalysis of O(2) electroreduction in an acidic medium. The catalyst precursors were synthesized by wet impregnation, planetary ball milling, a foaming-agent technique, or a templating method. All catalyst precursors were subjected to one or more heat treatments at 700-1050 degrees C in an inert or reactive atmosphere. These catalysts underwent an identical set of electrochemical characterizations, including rotating-disk-electrode and polymer-electrolyte membrane fuel cell (PEMFC) tests and voltammetry under N(2). Ex situ characterization was comprised of X-ray photoelectron spectroscopy, neutron activation analysis, scanning electron microscopy, and N(2) adsorption and its analysis with an advanced model for carbonaceous powders. In PEMFC, several NNMCs display mass activities of 10-20 A g(-1) at 0.8 V versus a reversible hydrogen electrode, and one shows 80 A g(-1). The latter value corresponds to a volumetric activity of 19 A cm(-3) under reference conditions and represents one-seventh of the target defined by the U.S. Department of Energy for 2010 (130 A cm(-3)). The activity of all NNMCs is mainly governed by the microporous surface area, and active sites seem to be hosted in pore sizes of 5-15 A. The nitrogen and metal (iron or cobalt) seem to be present in sufficient amounts in the NNMCs and do not limit activity. The paper discusses probable directions for synthesizing more active NNMCs. This could be achieved through multiple pyrolysis steps, ball-milling steps, and control of the powder morphology by the addition of foaming agents and/or sulfur.

Challenges and constraints of using oxygen cathodes in microbial fuel cells.

The performance of oxygen reduction catalysts (platinum, pyrolyzed iron(ll) phthalocyanine (pyr-FePc) and cobalt tetramethoxyphenylporphyrin (pyr-CoTMPP)) is discussed in light of their application in microbial fuel cells. It is demonstrated that the physical and chemical environment in microbial fuel cells severely affects the thermodynamics and the kinetics of the electrocatalytic oxygen reduction. The neutral pH in combination with low buffer capacities and low ionic concentrations strongly affect the cathode performance and limit the fuel cell power output. Thus, the limiting current density in galvanodyanamic polarization experiments decreases from 1.5 mA cm(-2) to 0.6 mA cm(-2) (pH 3.3, E(cathode) = 0 V) when the buffer concentration is decreased from 500 to 50 mM. The cathode limitations are superposed by the increasing internal resistance of the MFC that substantially contributes to the decrease of power output. For example, the maximum power output of a model MFC decreased by 35%, from 2.3 to 1.5 mW, whereas the difference between the electrode potentials (deltaE = E(anode) - E(cathode)) decreased only by 10%. The increase of the catalyst load of pyr-FePc from 0.25 to 2 mg cm(-2) increased the cathodic current density from 0.4 to 0.97 mA cm(-2) (pH 7, 50 mM phosphate buffer). The increase of the load of such inexpensive catalyst thus represents a suitable means to improve the cathode performance in microbial fuel cells. Due to the low concentration of protons in MFCs in comparison to relatively high alkali cation levels (ratio C(Na+,K+)/C(H+) = 5 x E5 in pH 7, 50 mM phosphate buffer) the transfer of alkali ions through the proton exchange membrane plays a major role in the charge-balancing ion flux from the anodic into the cathodic compartment. This leads to the formation of pH gradients between the anode and the cathode compartment.