How much protein and energy are needed to equilibrate nitrogen and energy balances in ventilated critically ill children?

BACKGROUND & AIMS: Protein and energy requirements in critically ill children are currently based on insufficient data. Moreover, longitudinal measurements of both total urinary nitrogen (TUN) and resting energy expenditure (REE) are lacking. The aim of this study was to investigate how much protein and energy are needed to equilibrate nitrogen and energy balances in ventilated critically ill children on the basis of daily measurements of TUN, REE and protein and energy intakes. Comparisons were made with the guidelines of the American Society for Parenteral and Enteral Nutrition and the Dietary Reference Intakes. METHODS: Children with an expected duration of mechanical ventilation ≥72 h were prospectively recruited. TUN was measured by chemiluminescence, and REE was measured by indirect calorimetry. Generalised linear models for longitudinal data were used to study the relation between protein intake and nitrogen balance and to calculate the minimum intake of protein needed to achieve nitrogen equilibrium. A similar approach was used for energy. Results were compared to the recommended values. RESULTS: Based on 402 measurements performed in 74 children (median age: 21 months), the mean TUN was high at 0.20 (95% CI: 0.20, 0.22) g/kg/d and the REE was 55 (95% CI: 54, 57) kcal/kg/d. Nitrogen and energy balances were achieved with 1.5 (95% CI: 1.4, 1.6) g/kg/d of protein and 58 (95% CI: 53, 63) kcal/kg/d for the entire group, but there were differences among children of different ages. Children required more protein and less energy than the Dietary Reference Intakes. CONCLUSIONS: In critically ill children, TUN was elevated and REE was reduced during the entire period of mechanical ventilation. Minimum intakes of 1.5 g/kg/d of protein and 58 kcal/kg/d can equilibrate nitrogen and energy balances in children up to 4 years old. Older children require more protein.

Muscle Characteristics and Substrate Energetics in Lifelong Endurance Athletes.

PURPOSE: The goal of this study was to explore the effect of lifelong aerobic exercise (i.e., chronic training) on skeletal muscle substrate stores (intramyocellular triglyceride [IMTG] and glycogen), skeletal muscle phenotypes, and oxidative capacity (ox), in older endurance-trained master athletes (OA) compared with noncompetitive recreational younger (YA) athletes matched by frequency and mode of training. METHODS: Thirteen OA (64.8 ± 4.9 yr) exercising 5 times per week or more were compared with 14 YA (27.8 ± 4.9 yr) males and females. IMTG, glycogen, fiber types, succinate dehydrogenase, and capillarization were measured by immunohistochemistry in vastus lateralis biopsies. Fat-ox and carbohydrate (CHO)-ox were measured by indirect calorimetry before and after an insulin clamp and during a cycle ergometer graded maximal test. RESULTS: V˙O2peak was lower in OA than YA. The OA had greater IMTG in all fiber types and lower glycogen stores than YA. This was reflected in greater proportion of type I and less type II fibers in OA. Type I fibers were similar in size, whereas type II fibers were smaller in OA compared with YA. Both groups had similar succinate dehydrogenase content. Numbers of capillaries per fiber were reduced in OA but with a higher number of capillaries per area. Metabolic flexibility and insulin sensitivity were similar in both groups. Exercise metabolic efficiency was higher in OA. At moderate exercise intensities, carbohydrate-ox was lower in OA but with similar Fat-ox. CONCLUSIONS: Lifelong exercise is associated with higher IMTG content in all muscle fibers and higher metabolic efficiency during exercise that are not explained by differences in muscle fibers types and other muscle characteristics when comparing older with younger athletes matched by exercise mode and frequency.

Optimal slopes and speeds in uphill ski mountaineering: a laboratory study.

The purpose of this study was to estimate the energy cost of linear (EC) and vertical displacement (ECvert), mechanical efficiency and main stride parameters during simulated ski mountaineering at different speeds and gradients, to identify an optimal speed and gradient that maximizes performance. 12 subjects roller skied on a treadmill at three different inclines (10, 17 and 24 %) at three different speeds (approximately 70, 80 and 85 % of estimated peak heart rate). Energy expenditure was calculated by indirect calorimetry, while biomechanical parameters were measured with an inertial sensor-based system. At 10 % there was no significant change with speed in EC, ECvert and mechanical efficiency. At 17 and 24 % the fastest speed was significantly more economical. There was a significant effect of gradient on EC, ECvert and mechanical efficiency. The most economical gradient was the steepest one. There was a significant increase of stride frequency with speed. At steep gradients only, relative thrust phase duration decreased significantly, while stride length increased significantly with speed. There was a significant effect of gradient on stride length (decrease with steepness) and relative thrust phase duration (increase with steepness). A combination of a decreased relative thrust phase duration with increased stride length and frequency decreases ECvert. To minimize the energy expenditure to reach the top of a mountain and to optimize performance, ski-mountaineers should choose a steep gradient (~24 %) and, provided they possess sufficient metabolic scope, combine it with a fast speed (~6 km h(-1)).

The relationship between virtual body ownership and temperature sensitivity.

In the rubber hand illusion tactile stimulation seen on a rubber hand, that is synchronous with tactile stimulation felt on the hidden real hand, can lead to an illusion of ownership over the rubber hand. This illusion has been shown to produce a temperature decrease in the hidden hand, suggesting that such illusory ownership produces disownership of the real hand. Here we apply immersive virtual reality (VR) to experimentally investigate this with respect to sensitivity to temperature change. Forty participants experienced immersion in a VR with a virtual body (VB) seen from a first person perspective. For half the participants the VB was consistent in posture and movement with their own body, and in the other half there was inconsistency. Temperature sensitivity on the palm of the hand was measured before and during the virtual experience. The results show that temperature sensitivity decreased in the consistent compared to the inconsistent condition. Moreover, the change in sensitivity was significantly correlated with the subjective illusion of virtual arm ownership but modulated by the illusion of ownership over the full virtual body. This suggests that a full body ownership illusion results in a unification of the virtual and real bodies into one overall entity - with proprioception and tactile sensations on the real body integrated with the visual presence of the virtual body. The results are interpreted in the framework of a"body matrix" recently introduced into the literature.

Compósitos colágeno aniônico: fosfato de cálcio. Preparação e caracterização

Anionic collagen: calcium phosphate composite was obtained by controlled mixing of collagen and calcium phosphate until the consistence of a past. Material was characterized by a Ca/P ratio of 1.55, with a X-ray diffraction pattern similar to that for hydroxyapatite. Differential Scanning Calorimetry showed that the protein is not denatured under the processing conditions. Scanning Electronic Microscopy showed that the mineral phase are regularly covered with collagen fibers, indicating that anionic collagen is efficient in the preparation of stable form of calcium phosphate ceramic paste.

Construção de equipamentos de refrigeração que permitem trabalhar com temperaturas de -40ºC ou -60ºC

In this article we describe the construction of two cooling systems with an immersion probe which will allow one to work at temperatures of either -40ºC or -60ºC. The two systems were constructed with readily available components and have been used daily for the last year in our laboratory to carry out reactions at low temperature or to cool down traps of vacuum pumps, reducing our need of dry-ice or liquid nitrogen.

Characterization of Mechanically Alloyed Nanocrystalline Fe(Al): Crystallite Size and Dislocation Density

A nanostructured disordered Fe(Al) solid solution was obtained from elemental powders of Fe and Al using a high-energy ball mill. The transformations occurring in the material during milling were studied with the use of X-ray diffraction. In addition lattice microstrain, average crystallite size, dislocation density, and the lattice parameter were determined. Scanning electron microscopy (SEM) was employed to examine the morphology of the samples as a function of milling times. Thermal behaviour of the milled powders was examined by differential scanning calorimetry (DSC). The results, as well as dissimilarity between calorimetric curves of the powders after 2 and 20 h of milling, indicated the formation of a nanostructured Fe(Al) solid solution

Escola, llengua i immigració a Catalunya. Algunes reflexions

L’article planteja que el model d’immersió lingüística que ha produït excel·lents resultats sobre la competència lingüística dels alumnes autòctons, presenta problemes a l’hora d’aplicar-lo a l’alumnat d’origen estranger, independentment de quina sigui la seva llengua inicial. Això és així perquè, d’una banda, aquests estudiants presenten un escenari d’escolarització molt diversificat, i de l’altra, perquè les seves actituds lingüístiques són diferents de les que s’havien conegut fins ara. Tot plegat comporta que, pel que fa a les habilitats lingüístiques, assoleixin uns resultats més baixos que els autòctons

Estudo calorimétrico da interação de álcoois com Saccharomyces cerevisiae a 298 K

The calorimetric experiments based on technique breaking ampoule were carried out by measuring of the heat of solution of alcohol in isotonic solution (NaCl 0.10 M) and alcohol in suspension of Sc at 298 K. From these data the enthalpy of interaction alcohol with suspension of Sc (DtrsH°) was calculate by Hess law. In this study, the results indicate that the enthalpy of interaction of aliphatic alcohol (C2-C8) with suspensions of Sc is a process exothermic and becomes more exothermic with increasing of -CH2 group of alcohol in range -1,14 to -4,0 kJ.mol-1. We concluded that enthalpy of interaction shows a linear relationship with increasing of alcohol's lipophilicity, in agreement with Traube's rule.

Inclusion complex of the antiviral drug acyclovir with cyclodextrin in aqueous solution and in solid phase

Complexation between acyclovir (ACV), an antiviral drug used for the treatment of herpes simplex virus infection, and beta-cyclodextrin (beta-CD) was studied in solution and in solid states. Complexation in solution was evaluated using solubility studies and nuclear magnetic resonance spectroscopy (¹H-NMR). In the solid state, X-ray diffraction, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and dissolution studies were used. Solubility studies suggested the existence of a 1:1 complex between ACV and beta-CD. ¹H-NMR spectroscopy studies showed that the complex formed occurs with a stoichiometry ratio of 1:1. Powder X-ray diffraction indicated that ACV exists in a semicrystalline state in the complexed form with beta-CD. DSC studies showed the existence of a complex of ACV with beta-CD. The TGA studies confirmed the DSC results of the complex. Solubility of ACV in solid complexes was studied by the dissolution method and it was found to be much more soluble than the uncomplexed drug.

Estudo termogravimétrico e calorimétrico da algaroba

Humidity and ash content of powder and bran of algaroba pods are important quality parameters for biological control during storage. The studies of humidity and ash content were carried out conventional and thermogravimetric methods. Different values were obtained by the various methods. The thermogravimetric method was faster and required less sample for the humidity and ash analyses of the powder and bran of algaroba pods. The differential scanning calorimetry curves of the powder and bran of algaroba pods, dryed at 55 ºC, showed two peaks, one corresponding to the gelatinization of starch and the other to the vaporization of water. The samples dryed at 65, 75, 85, 95 and 105 ºC showed one peak, corresponding to the vaporization of water.

Efeito da concentração do catalisador acetilacetonato férrico na cura de poliuretano à base de polibutadieno líquido hidroxilado (PBLH) e diisocianato de isoforona (IPDI)

The reaction between hydroxy-terminated polybutadiene and isophorone diisocyanate constitutes the base of the curing process of the most composite solid propellant used in the propulsion of solid rocket propellant. In this work, differential scanning calorimetry and viscosity measurements were used to evaluate the effect of the ferric acetylacetonate catalyst concentration on the reaction between HTBR and IPDI. These analyses show one exotherm, which shifts to lower temperatures as the catalyst concentration increases. The viscosity analyses show that the increase of temperature causes, at first, a reduction in the mixture viscosity, reaching a minimum range called gelification region (increasing the crosslinking density).

Influência de alguns parâmetros experimentais nos resultados de análises calorimétricas diferenciais - DSC

A series of experiments were performed in order to demonstrate to undergraduate students or users of the differential scanning calorimetry (DSC), that several factors can influence the qualitative and quantitative aspects of DSC results. Saccharin, an artificial sweetner, was used as a probe and its thermal behavior is also discussed on the basis of thermogravimetric (TG) and DSC curves.

Obtenção e caracterização de blendas colágeno-quitosana

Biodegradable polymer blends were obtained using collagen and chitosan. Membranes of collagen and chitosan in different proportions (3:1, 1:1 and 1:3) were prepared by mixing their acetate solutions (pH 3.5) at room temperature. The blends were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier Transform infrared (FTIR) spectroscopy, specific viscosity, water absorption and stress-strain assays. The results showed that chitosan did not interfere in the structural arrangement of the collagen triple helix and the properties of the blends can be controlled by varing the proportion of the collagen and the chitosan.

Cristalização e taxa crítica de resfriamento para vitrificação do poli(sebacato de decametileno)

We synthesized Poly(decamethylene sebacate) - P10MS - and studied its overall crystallization rates in a range of temperatures using Differential Scanning Calorimetry in isothermal conditions, which enabled us to identify the crystallization mechanism by means of the Johnson-Mehl-Avrami-Kolmogorov equation. The critical cooling rate (Rc) to vitrify the P10MS was determined using a non-isothermal method proposed by Barandiarán & Colmenero (BC). The value of Rc is around 50-250 K/s, which confirms the experimentally observed difficulty to vitrify this polymer.