The Regulation of Rat Liver Xanthine Oxidase CONVERSION IN VITRO OF THE ENZYME ACTIVITY FROM DEHYDROGENASE (TYPE D) TO OXIDASE (TYPE O)

Abstract The aerobic oxidation of xanthine by rat liver supernatant was greatly stimulated by the addition of methylene blue or of NAD+: the latter was reduced during the reaction. Storage of the supernatant at -20° brought about an enhancement of the xanthine oxidation rate measured without addition of cofactors. A similar "activation" was caused by prior incubation at 37° of the unfractionated liver homogenate, or of the supernatant separated after sonic disruption of the homogenate. The same effect was obtained by treatment with solvents, or by prior incubation at 37° of the supernatant in the presence of proteolytic enzymes or under anaerobic conditions. The presence of xanthine accelerated the effect of proteolytic enzymes and of anaerobiosis. Only the changes caused by anaerobiosis could be reversed by incubating the supernatant in air before the assay. The reaction rate was apparently unaffected by these treatments if activity of the enzyme was measured in the presence of methylene blue or of NAD+. The latter, however, was not reduced during the oxidation of xanthine by "activated" supernatants stored at -20° if the reaction was run in the presence of oxygen. If the reaction was in anaerobiosis, uric acid and a corresponding amount of NADH were formed by fresh, supernatant, and by supernatants activated at -20° or by prior incubation in anaerobiosis, but not by supernatant activated by trypsin. The hypothesis is formulated that most of the xanthine oxidase of rat liver supernatant is a dehydrogenase (Type D), and may be converted (activated) into an oxidase (Type O)

Photometry of the Oort Cloud comet C/2009 P1(Garradd): pre-perihelion observations at 5.7 and 2.5 AU

The aim of this paper is to contribute to the characterization of the general properties of the Long Period Comets (LPCs) family, and in particular to report on the dust environment of comet C/2009 P1 (Garradd). The comet was observed at two epochs pre-perihelion, at ~6 AU and at ~2.5 AU: broad-band images have been used to investigate its coma morphology and properties and to model the dust production rate. Comet C/2009 P1 (Garradd) is one of the most active and “dust producing” LPCs ever observed, even at the large heliocentric distance rh~6 AU. Its coma presents a complex morphology, with subtle structures underlying the classical fan-shaped tail, and, at rh~2.5 AU, also jet-like structures and spiralling outflows. In the reference aperture of radius ρ=5°×104 km, the R-Afρ is 3693±156 cm and 6368±412 cm, in August 2010 (rh~6 AU) and July 2011 (rh~2.5 AU), respectively. The application of a first order photometric model, under realistic assumptions on grain geometric albedo, power-law dust size distribution, phase darkening function and grain dust outflow velocity, yielded a measure of the dust production rate for the two epochs of observation of Qd=7.27×102 kg/s and Qd=1.37×103 kg/s, respectively, for a reference outflow dust velocity of vsmall=25 m/s for small (0.1–10 µm) grains and vlarge=1 m/s for large (10 µm–1 cm) grains. These results suggest that comet Garradd is one of the most active minor bodies observed in recent years, highly contributing to the continuous replenishment of the Interplanetary Dust Complex also in the outer Solar System, and pose important constraints on the mechanism(s) driving the cometary activity at large heliocentric distances

CORRELATION BETWEEN MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Al-Si CAST ALLOYS

The influence of microstructure and process history on mechanical behaviour of cast Al-Si alloys is reported.In the present work, the EN-AC 46000 and 46100 aluminium alloys have been gravity cast using a stepbarpermanent mould, with a range of thickness going from 5 to 20 mm. Metallographic and image analysistechniques have been used to quantitatively examine the microstructural parameters of the ?-Al phaseand eutectic Silicon. Microstructure has been also correlated with the results coming from the numericalsimulation of the casting process. The results show that SDAS and length of eutectic silicon particles increasewith section thickness, and consequently mechanical properties decrease

Comet 67P/Churyumov-Gerasimenko preserved the pebbles that formed planetesimals

Solar System formation models predict that the building-blocks of planetesimals were mm- to cm-sized pebbles, aggregates of ices and non-volatile materials, consistent with the compact particles ejected by comet 67P/Churyumov-Gerasimenko (67P hereafter) and detected by GIADA (Grain Impact Analyzer and Dust Accumulator) on-board the Rosetta spacecraft. Planetesimals were formed by the gentle gravitational accretion of pebbles, so that they have an internal macroporosity of 40%. We measure the average dust bulk density ${\rho}D = 795 _{-65}^{+840} kg m^{-3}$ that, coupled to the 67P nucleus bulk density, provides the average dust-to-ices mass ratio δ = 8.5. We find that the measured densities of the 67P pebbles are consistent with a mixture of (15 ± 6)% of ices, (5 ± 2)% of Fe-sulfides, (28 ± 5)% of silicates, and (52 ± 12)% of hydrocarbons, in average volume abundances. This composition matches both the solar and CI-chondritic chemical abundances, thus showing that GIADA has sampled the typical non-volatile composition of the pebbles that formed all planetesimals. The GIADA data do not constrain the abundance of amorphous silicates vs. crystalline Mg,Fe- olivines and pyroxenes. We find that the pebbles have a microporosity of (52 ± 8)% (internal volume filling factor φP = 0.48±0.08), implying an average porosity for the 67P nucleus of (71 ± 8)%, lower than previously estimated

Valproic acid and phenobarbital blood levels during the first month of treatment with the ketogenic diet.

Objective – The aim of this study was to assess how the ketogenic diet influences the blood levels of antiepileptic drugs in the first month of treatment in a pediatric population with drug-resistant epilepsy. Methods – The plasma concentrations of antiepileptic drugs were investigated in an open study on 36 consecutive children and adolescents (20 males), aged between 6 months and 16 years (mean age 4.7 years), who were put on the ketogenic diet because of medically refractory epilepsy. The plasma levels of antiepileptic drugs were determined 30 days and immediately before the diet and on days 8, 15, 22 and 29 after the start of the diet. The daily dose of each drug was not changed during the first month of treatment, while the daily dose of benzodiazepines was reduced by up to 30% if excessive sedation or drowsiness occurred. Results – While plasma concentrations of phenobarbital did not change in the first month on the ketogenic diet (mean increase of 2.3 mg ⁄ l 1.0), valproic acid showed a slight but not significant decrease (mean decresase of 6.7 mg ⁄ l 3.2), 2 weeks after the start of the diet. Conclusions – Adjustments in the daily dose of either drug before the start of the diet do not however appear to be justified

Mental health services utilization after Mariana dam burst

Abstract Background The global burden of mental health conditions is increasing, especially in middle- and low-income countries and frequently the quality of mental health services is lower than the quality of services for other conditions. Disasters may increase this burden through their direct impact or due to secondary stressors, such as the preclusion of access to essential services. The aim of this study is to assess the impact of Mariana dam burst (Brazil) in November 2015, in the utilization of public mental health services by the population that experienced an interruption of water supply after the event. Methods We used data from DATASUS, the database of the Brazilian public health system, analyzing data from 34 months before to 36 months after the event. We defined as affected the population living in the municipalities of Minas Gerais state that had an interruption of water supply after the event and the rest of the state population as the comparison group. We designed an Interrupted time-series analysis to evaluate both immediate and gradual changes in use of mental health services after the accident. Results The affected population included 381,749 inhabitants and the comparison group 20,487,352 inhabitants. The monthly rate of mental health visits in the affected population in the beginning of the series was 296 (CI 182 to 409, p < 0.001) per 100.000 person-month. Comparing the groups after the event, we observed a non-statistically significant higher increase in the rate of visits immediately after the event of 115.96 (CI -30.00 to 261.92, p = 0.118) and a significant increase in the monthly rate of visits (change in slope) of 15.55 (CI 8.19 to 22.92, p < 0.001) in the affected group. Discussion The results suggest that the event translated in a long-term increase in mental health services utilization. We believe that this study presents an innovative methodology on the assessment of mental health services after disasters and that it could be adapted to other contexts. Key messages Indirect impacts of disasters may be associated with long-term changes in the utilization of mental health services. Interrupted time series using routine data are useful tools for the assessment of health services utilization following disasters

The Need for a Specific Risk Prediction System in Native Valve Infective Endocarditis Surgery

The need for a specific risk score system for infective endocarditis (IE) surgery has been previously claimed. In a single-center pilot study, preliminary to future multicentric development and validation, bivariate and multivariate (logistic regression) analysis of early postoperative mortality predictors in 440 native valve IE patients were performed. Mathematical procedures assigned scores to the independent predictors emerged (AUC of the ROC curve: 0.88). Overall mortality was 9.1%. Six predictors were identified and assigned scores, including age (5–13 points), renal failure (5), NYHA class IV (9), critical preoperative state (11), lack of preoperative attainment of blood culture negativity (5), perivalvular involvement (5). Four risk classes were drawn ranging from “very low risk” (≤5 points, mean predicted mortality 1%), and to “very high risk” (≥20 points, 43% mortality). IE-specific risk stratification models are both needed, as disease-specific factors (e.g., cultures, abscess), beside the generic ones (e.g., age, renal impairment) affect mortality, and feasible

Combination Forecasts of Bond and Stock Returns: An Asset Allocation Perspective

We investigate the out-of-sample forecasting ability of the HML, SMB, momentum, short-term and long-term reversal factors along with their size and value decompositions on U.S. bond and stock returns for a variety of horizons ranging from the short run (1 month) to the long run (2 years). Our findings suggest that these factors contain significantly more information for future bond and stock market returns than the typically employed financial variables. Combination of forecasts of the empirical factors turns out to be particularly successful, especially from an an asset allocation perspective. Similar findings pertain to the European and Japanese markets

A Kalman filter single point positioning for maritime applications using a smartphone

Different positioning techniques have been largely adopted for maritime applications that require high accuracy kinematic positioning. The main objective of the paper is the performance assessment of a Single Point Positioning algorithm (SPP), with a Kalman filter (KF) estimator, adapted for maritime applications. The KF has been chosen as estimation technique due to the ability to consider both the state vector dynamic and the measurements. Particularly, in order to compute an accurate vertical component of the position, suitable for maritime applications, the KF settings have been modified by tuning the covariance matrix of the process noise. The algorithm is developed in Matlab environment and tested using multi-GNSS single-frequency raw data, collected by a smartphone located on board a moving ship. The algorithm performance evaluation is carried out in position domain and the results show an enhancement of meter order on vertical component compared to the classical SPP based on Least Square estimation technique. In addition, different GNSSs configurations are considered to verify the benefits of their integration in terms of accuracy, solution availability and geometry

The <i>Castalia</i> mission to Main Belt Comet 133P/Elst-Pizarro

We describe Castalia, a proposed mission to rendezvous with a Main Belt Comet (MBC), 133P/Elst-Pizarro. MBCs are a recently discovered population of apparently icy bodies within the main asteroid belt between Mars and Jupiter, which may represent the remnants of the population which supplied the early Earth with water. Castalia will perform the first exploration of this population by characterising 133P in detail, solving the puzzle of the MBC’s activity, and making the first in situ measurements of water in the asteroid belt. In many ways a successor to ESA’s highly successful Rosetta mission, Castalia will allow direct comparison between very different classes of comet, including measuring critical isotope ratios, plasma and dust properties. It will also feature the first radar system to visit a minor body, mapping the ice in the interior. Castalia was proposed, in slightly different versions, to the ESA M4 and M5 calls within the Cosmic Vision programme. We describe the science motivation for the mission, the measurements required to achieve the scientific goals, and the proposed instrument payload and spacecraft to achieve these