Clinical relevance of L-carnitine-supplemented total parenteral nutrition in postoperative trauma. Metabolic effects of continuous or acute carnitine administration with special reference to fat oxidation and nitrogen utilization.

Carnitine-free total parenteral nutrition (TPN) is claimed to result in a carnitine deficiency with subsequent impairment of fat oxidation. The present study was designed to evaluate the possible benefit of carnitine supplementation on postoperative fat and nitrogen utilization. Sixteen patients undergoing total esophagectomy were evenly randomized and received TPN without or with L-carnitine supplementation (74 mumol.kg-1.d-1) during 11 postoperative days. On day 11, a 4-h infusion of L-carnitine (125 mumol/kg) was performed in both groups. The effect of supplementation was evaluated by indirect calorimetry, N balance, and repeated measurements of plasma lipids and ketone bodies. Irrespective of continuous or acute supplementation, respiratory quotient and fat oxidation were similarly maintained throughout the study in both groups whereas N balance appeared to be more favorable without carnitine. We conclude that carnitine-supplemented TPN does not improve fat oxidation or promote N utilization in the postoperative phase.

Répercussions de l'agression sur le métabolisme et la composition corporelle chez l'individu obèse : Nutrition de l'obèse agressé. [Repercussions of injury on metabolic and body composition factors in obese individuals : Nutrition and obese critical patients]

La réponse métabolique de l'obèse apparemment « sainen situation d'agression aiguë (polytraumatisés, traumatisés crâniens, patients chirurgicaux, grands brûlés, opérations électives) ne se distingue pas ou peu de celle de l'individu non-obèse. Cependant, les complications médicales liées à l'agression (insuffisances respiratoire et cardiaque, bronchopneumonie, infections de plaies, thrombophlébites et embolies) demeurent plus importantes chez l'obèse morbide que chez l'individu de poids normal. Grâce à l'inflation de ses réserves énergétiques, l'obèse apparemment sain est avantagé, par rapport au sujet mince, au cours d'une agression nutritionnelle chronique telle que le jeûne prolongé. Le facteur fonctionnel limitant la survie dépend avant tout de la composition corporelle initiale et du degré d'adaptation métabolique (et comportementale) en particulier du degré de conservation de la masse maigre par rapport à la masse grasse. La mobilisation accrue de la masse grasse associée à la perte de poids chez l'obèse (par rapport à son homologue non-obèse) est favorable à une prolongation de la vie, car, en brûlant davantage de graisse corporelle, la part des protéines corporelles endogènes utilisée à des fins énergétiques est plus faible. Il s'ensuit chez l'obèse qu'un niveau de masse maigre critique pour la survie n'est atteint qu'après une réduction très marquée de ses réserves énergétiques. En revanche, le sujet mince perd davantage de masse maigre lors de l'amaigrissement et, par conséquent, son métabolisme de repos diminuera plus rapidement que celui du sujet obèse. Cela peut constituer un avantage énergétique évident en termes d'économie d'énergie consécutive à l'adaptation métabolique, mais un inconvénient majeur quant à la durée de la survie. The metabolic response of « apparently healthyobese individuals following acute injury (multiple trauma, head injury and surgical patients, extended burns, elective surgery) is not dramatically different from that of a non-obese individuals. However, the medical complications following the injury (respiratory and cardiac insufficiency, broncho-pneumonia, infections of wounds, trombophlebitis and embolism) are more prevalent in morbid obese patients than in individuals of normal body weight. Because of a large increase in their individuals energy store, "apparently healthy" obese individuals have an advantage over very lean subjects when exposed to a chronic nutritional aggression such as total fasting. The functional limiting factor for survival depends primarily on initial body composition and the magnitude of metabolic adaptation (including behavioral adaptation). The key factor is the extent to which the fat-free mass is maintained (versus to the fat mass) during weight loss. The increased proportion of body fat mobilized during weight loss in obese patients, compared with their non-obese counterparts, favors prolonged survival, because more adipose tissue is burned off, the fraction of body protein endogenously utilized for energy purpose individuals, is smaller. This implies that obese individuals do not reach a fat-free mass "critical" for their survival until their energy stores reach very low values. In contrast, lean subject tend to lose more fat-free mass during weight loss than obese subjects and, as a result, their energy expenditure drops more rapidly. This may offer a potential advantage in terms of energy economy (more energy saving) but a major disadvantage in terms of duration of survival.

A programming environment having three levels of complexity for mobile robotics = Entorno de programación con tres niveles de complejidad para robótica móvil

This paper presents a programming environment for supporting learning in STEM, particularly mobile robotic learning. It was designed to maintain progressive learning for people with and without previous knowledge of programming and/or robotics. The environment was multi platform and built with open source tools. Perception, mobility, communication, navigation and collaborative behaviour functionalities can be programmed for different mobile robots. A learner is able to programme robots using different programming languages and editor interfaces: graphic programming interface (basic level), XML-based meta language (intermediate level) or ANSI C language (advanced level). The environment supports programme translation transparently into different languages for learners or explicitly on learners’ demand. Learners can access proposed challenges and learning interfaces by examples. The environment was designed to allow characteristics such as extensibility, adaptive interfaces, persistence and low software/hardware coupling. Functionality tests were performed to prove programming environment specifications. UV BOT mobile robots were used in these tests

Induced normothermia attenuates cerebral metabolic distress in patients with aneurysmal subarachnoid hemorrhage and refractory Fever.

BACKGROUND AND PURPOSE: The purpose of this study was to analyze whether fever control attenuates cerebral metabolic distress after aneurysmal subarachnoid hemorrhage (SAH). METHODS: Eighteen SAH patients, who underwent intracranial pressure (ICP) and cerebral microdialysis monitoring and were treated with induced normothermia for refractory fever (body temperature >or=38.3 degrees C, despite antipyretics), were studied. Levels of microdialysate lactate/pyruvate ratio (LPR) and episodes of cerebral metabolic crisis (LPR >40) were analyzed during fever and induced normothermia, at normal and high ICP (>20 mm Hg). RESULTS: Compared to fever, induced normothermia resulted in lower LPR (40+/-24 versus 32+/-9, P<0.01) and a reduced incidence of cerebral metabolic crisis (13% versus 5%, P<0.05) at normal ICP. During episodes of high ICP, induced normothermia was associated with a similar reduction of LPR, fewer episodes of cerebral metabolic crisis (37% versus 8%, P<0.01), and lower ICP (32+/-11 versus 28+/-12 mm Hg, P<0.05). CONCLUSIONS: Fever control is associated with reduced cerebral metabolic distress in patients with SAH, irrespective of ICP.

Fetal programming of pulmonary vascular dysfunction in mice: role of epigenetic mechanisms.

Insults during the fetal period predispose the offspring to systemic cardiovascular disease, but little is known about the pulmonary circulation and the underlying mechanisms. Maternal undernutrition during pregnancy may represent a model to investigate underlying mechanisms, because it is associated with systemic vascular dysfunction in the offspring in animals and humans. In rats, restrictive diet during pregnancy (RDP) increases oxidative stress in the placenta. Oxygen species are known to induce epigenetic alterations and may cross the placental barrier. We hypothesized that RDP in mice induces pulmonary vascular dysfunction in the offspring that is related to an epigenetic mechanism. To test this hypothesis, we assessed pulmonary vascular function and lung DNA methylation in offspring of RDP and in control mice at the end of a 2-wk exposure to hypoxia. We found that endothelium-dependent pulmonary artery vasodilation in vitro was impaired and hypoxia-induced pulmonary hypertension and right ventricular hypertrophy in vivo were exaggerated in offspring of RDP. This pulmonary vascular dysfunction was associated with altered lung DNA methylation. Administration of the histone deacetylase inhibitors butyrate and trichostatin A to offspring of RDP normalized pulmonary DNA methylation and vascular function. Finally, administration of the nitroxide Tempol to the mother during RDP prevented vascular dysfunction and dysmethylation in the offspring. These findings demonstrate that in mice undernutrition during gestation induces pulmonary vascular dysfunction in the offspring by an epigenetic mechanism. A similar mechanism may be involved in the fetal programming of vascular dysfunction in humans.

Special commentary : a call for intensive metabolic support.

PURPOSE OF REVIEW: This special commentary addresses recent clinical reviews regarding appropriate nutrition and metabolic support in the critical care setting. RECENT FINDINGS: There are divergent approaches between North America and Europe for the use of early nutrition support and combined enteral nutrition and parenteral nutrition support possibly due to the commercial availability of specific parenteral nutrients. The advent of intensive insulin therapy has changed the landscape of metabolic support in the intensive care unit, and previous notions about infective risk of parenteral nutrition will need to be re-addressed. Patients with brain failure may benefit from an intensive insulin therapy with a blood glucose target that is higher than that used in patients without brain failure. Patients with heart failure may benefit from the addition of nutritional pharmacology that targets proximate oxidative pathophysiological pathways. Intradialytic parenteral nutrition may be viewed as another form of supplemental parenteral nutrition when enteral nutrition is insufficient in patients on hemodialysis in the intensive care unit. SUMMARY: It is proposed that intensive metabolic support be routinely implemented in the intensive care unit based on the following steps: intensive insulin therapy with an appropriate blood glucose target, nutrition risk assessment, early and if needed combined enteral nutrition and parenteral nutrition to target 20-25 kcal/kg/day and 1.2-1.5 g protein/kg/day, and nutritional and metabolic monitoring.

Relationships of basal metabolic rate, relative testis size and cycle length of spermatogenesis in shrews (Mammalia, Soricidae).

The aim of the present study was to determinate the cycle length of spermatogenesis in three species of shrew, Suncus murinus, Sorex coronatus and Sorex minutus, and to assess the relative influence of variation in basal metabolic rate (BMR) and mating system (level of sperm competition) on the observed rate of spermatogenesis, including data of shrew species studied before (Sorex araneus, Crocidura russula and Neomys fodiens). The dynamics of sperm production were determined by tracing 5-bromodeoxyuridine in the DNA of germ cells. As a continuous scaling of mating systems is not evident, the level of sperm competition was evaluated by the significantly correlated relative testis size (RTS). The cycle durations estimated by linear regression were 14.3 days (RTS 0.3%) in Suncus murinus, 9.0 days (RTS 0.5%) in Sorex coronatus and 8.5 days (RTS 2.8%) in Sorex minutus. In regression and multiple regression analyses including all six studied species of shrew, cycle length was significantly correlated with BMR (r2=0.73) and RTS (r2=0.77). Sperm competition as an ultimate factor obviously leads to a reduction in the time of spermatogenesis in order to increase sperm production. BMR may act in the same way, independently or as a proximate factor, revealed by the covariation, but other factors (related to testes size and thus to mating system) may also be involved.

UniPathway: a resource for the exploration and annotation of metabolic pathways.

UniPathway (http://www.unipathway.org) is a fully manually curated resource for the representation and annotation of metabolic pathways. UniPathway provides explicit representations of enzyme-catalyzed and spontaneous chemical reactions, as well as a hierarchical representation of metabolic pathways. This hierarchy uses linear subpathways as the basic building block for the assembly of larger and more complex pathways, including species-specific pathway variants. All of the pathway data in UniPathway has been extensively cross-linked to existing pathway resources such as KEGG and MetaCyc, as well as sequence resources such as the UniProt KnowledgeBase (UniProtKB), for which UniPathway provides a controlled vocabulary for pathway annotation. We introduce here the basic concepts underlying the UniPathway resource, with the aim of allowing users to fully exploit the information provided by UniPathway.

Reexamination of the relationship of resting metabolic rate to fat-free mass and to the metabolically active components of fat-free mass in humans.

The ratio of resting metabolic rate (RMR) to fat-free mass (FFM) is often used to compare individuals of different body sizes. Because RMR has not been well described over the full range of FFM, a literature review was conducted among groups with a wide range of FFM. It included 31 data sets comprising a total of 1111 subjects: 118 infants and preschoolers, 323 adolescents, and 670 adults; FFM ranged from 2.8 to 106 kg. The relationship of RMR to FFM was found to be nonlinear and average slopes of the regression equations of the three groups differed significantly (P less than 0.0001). For only the youngest group did the intercept approach zero. The lower slopes of RMR on FFM, at higher measures of FFM, corresponded to relatively greater proportions of less metabolically active muscle mass and to lesser proportions of more metabolically active nonmuscle organ mass. Because the contribution of FFM to RMR is not constant, an arithmetic error is introduced when the ratio of RMR to FFM is used. Hence, alternative methods should be used to compare individuals with markedly different FFM.

Python as a programming language for the introductory programming courses

Tämä kandidaatintyö tutkii tietotekniikan perusopetuksessa keskeisen aiheen,ohjelmoinnin, alkeisopetusta ja siihen liittyviä ongelmia. Työssä perehdytään ohjelmoinnin perusopetusmenetelmiin ja opetuksen lähestymistapoihin, sekä ratkaisuihin, joilla opetusta voidaan tehostaa. Näitä ratkaisuja työssä ovat mm. ohjelmointikielen valinta, käytettävän kehitysympäristön löytäminen sekä kurssia tukevien opetusapuvälineiden etsiminen. Lisäksi kurssin läpivientiin liittyvien toimintojen, kuten harjoitusten ja mahdollisten viikkotehtävien valinta kuuluu osaksitätä työtä. Työ itsessään lähestyy aihetta tutkimalla Pythonin soveltuvuutta ohjelmoinnin alkeisopetukseen mm. vertailemalla sitä muihin olemassa oleviin yleisiin opetuskieliin, kuten C, C++ tai Java. Se tarkastelee kielen hyviä ja huonoja puolia, sekä tutkii, voidaanko Pythonia hyödyntää luontevasti pääasiallisena opetuskielenä. Lisäksi työ perehtyy siihen, mitä kaikkea kurssilla tulisi opettaa, sekä siihen, kuinka kurssin läpivienti olisi tehokkainta toteuttaa ja minkälaiset tekniset puitteet kurssin toteuttamista varten olisi järkevää valita.

Defective nitric oxide synthesis: a link between metabolic insulin resistance, sympathetic overactivity and cardiovascular morbidity.

Epidemiological studies demonstrate an association between insulin resistance, hypertension and cardiovascular morbidity. In addition to its metabolic effects, insulin also has important cardiovascular actions. The sympathetic nervous system and the nitric oxide-l-arginine pathway have emerged as central players in the mediation of these actions. Over the past decade, the underlying mechanisms and the factors that may govern the interaction between insulin and these two major cardiovascular regulatory systems have been studied extensively in healthy people and insulin-resistant individuals. Here we summarize the current understanding and gaps in knowledge on these interactions. We propose that a genetic and/or acquired defect of nitric oxide synthesis could represent a central defect triggering many of the metabolic, vascular and sympathetic abnormalities characteristic of insulin-resistant states, all of which may predispose to cardiovascular disease.

Neuro-mechanical and metabolic adjustments to the repeated anaerobic sprint test in professional football players.

PURPOSE: This study aimed to determine the neuro-mechanical and metabolic adjustments in the lower limbs induced by the running anaerobic sprint test (the so-called RAST). METHODS: Eight professional football players performed 6 × 35 m sprints interspersed with 10 s of active recovery on artificial turf with their football shoes. Sprinting mechanics (plantar pressure insoles), root mean square activity of the vastus lateralis (VL), rectus femoris (RF), and biceps femoris (BF) muscles (surface electromyography, EMG) and VL muscle oxygenation (near-infrared spectroscopy) were monitored continuously. RESULTS: Sprint time, contact time and total stride duration increased from the first to the last repetition (+17.4, +20.0 and +16.6 %; all P < 0.05), while flight time and stride length remained constant. Stride frequency (-13.9 %; P < 0.001) and vertical stiffness decreased (-27.2 %; P < 0.001) across trials. Root mean square EMG activities of RF and BF (-18.7 and -18.1 %; P < 0.01 and 0.001, respectively), but not VL (-1.2 %; P > 0.05), decreased over sprint repetitions and were correlated with the increase in running time (r = -0.82 and -0.90; both P < 0.05). Together with a better maintenance of RF and BF muscles activation levels over sprint repetitions, players with a better repeated-sprint performance (lower cumulated times) also displayed faster muscle de- (during sprints) and re-oxygenation (during recovery) rates (r = -0.74 and -0.84; P < 0.05 and 0.01, respectively). CONCLUSION: The repeated anaerobic sprint test leads to substantial alterations in stride mechanics and leg-spring behaviour. Our results also strengthen the link between repeated-sprint ability and the change in neuromuscular activation as well as in muscle de- and re-oxygenation rates.

Metabolic responses of guava trees irrigated withdifferent N and K levels in São Francisco Valley

The guava (Psidium guajava L.) cv. Paluma has been cultivated in São Francisco Valley, Northeastern of Brazil, for in natura consumption and processing purposes. In spite of its importance, there are few scientific knowledge regarding guava physiology, nutrition, irrigation and fertigation. The objective of this work was to evaluate the effect of weather conditions and different concentrations of N and K applied by fertigation in foliar contents of reducing sugars, total soluble sugars, starch, sucrose, amino acids, and proteins. The field experiment was carried out at Bebedouro Experimental Field and the biochemical evaluations at the Laboratory of Seed and Plant Physiology, both located at Embrapa Semi-Árido, Petrolina-PE. The doses of 200 g N and 100 g K2O; 400 g N and 200 g K2O; 600 g N and 300 g K2O; and 800 g N and 400 g K2O per plant were applied in an experiment field. The experimental design was totally randomized blocks, with four treatments and five blocks. The weather conditions influenced the plant photosynthesis, which affects the plants metabolism. Guava presented specific responses to N and K fertigation for each parameter evaluated. The weather conditions during the evaluation period influenced guava responses to N and K fertigation.

Steady-state global optimization of metabolic non-linear dynamic models through recasting into power-law canonical models

Background: Design of newly engineered microbial strains for biotechnological purposes would greatly benefit from the development of realistic mathematical models for the processes to be optimized. Such models can then be analyzed and, with the development and application of appropriate optimization techniques, one could identify the modifications that need to be made to the organism in order to achieve the desired biotechnological goal. As appropriate models to perform such an analysis are necessarily non-linear and typically non-convex, finding their global optimum is a challenging task. Canonical modeling techniques, such as Generalized Mass Action (GMA) models based on the power-law formalism, offer a possible solution to this problem because they have a mathematical structure that enables the development of specific algorithms for global optimization. Results: Based on the GMA canonical representation, we have developed in previous works a highly efficient optimization algorithm and a set of related strategies for understanding the evolution of adaptive responses in cellular metabolism. Here, we explore the possibility of recasting kinetic non-linear models into an equivalent GMA model, so that global optimization on the recast GMA model can be performed. With this technique, optimization is greatly facilitated and the results are transposable to the original non-linear problem. This procedure is straightforward for a particular class of non-linear models known as Saturable and Cooperative (SC) models that extend the power-law formalism to deal with saturation and cooperativity. Conclusions: Our results show that recasting non-linear kinetic models into GMA models is indeed an appropriate strategy that helps overcoming some of the numerical difficulties that arise during the global optimization task.

Identifying the preferred subset of enzymatic profiles in nonlinear kinetic metabolic models via multiobjective global optimization and pareto filters

Optimization models in metabolic engineering and systems biology focus typically on optimizing a unique criterion, usually the synthesis rate of a metabolite of interest or the rate of growth. Connectivity and non-linear regulatory effects, however, make it necessary to consider multiple objectives in order to identify useful strategies that balance out different metabolic issues. This is a fundamental aspect, as optimization of maximum yield in a given condition may involve unrealistic values in other key processes. Due to the difficulties associated with detailed non-linear models, analysis using stoichiometric descriptions and linear optimization methods have become rather popular in systems biology. However, despite being useful, these approaches fail in capturing the intrinsic nonlinear nature of the underlying metabolic systems and the regulatory signals involved. Targeting more complex biological systems requires the application of global optimization methods to non-linear representations. In this work we address the multi-objective global optimization of metabolic networks that are described by a special class of models based on the power-law formalism: the generalized mass action (GMA) representation. Our goal is to develop global optimization methods capable of efficiently dealing with several biological criteria simultaneously. In order to overcome the numerical difficulties of dealing with multiple criteria in the optimization, we propose a heuristic approach based on the epsilon constraint method that reduces the computational burden of generating a set of Pareto optimal alternatives, each achieving a unique combination of objectives values. To facilitate the post-optimal analysis of these solutions and narrow down their number prior to being tested in the laboratory, we explore the use of Pareto filters that identify the preferred subset of enzymatic profiles. We demonstrate the usefulness of our approach by means of a case study that optimizes the ethanol production in the fermentation of Saccharomyces cerevisiae.