Optimization of patient positioning for improved healing after corneal transplantation.

Corneal transplantation is the only solution which avoids loss of vision, when endothelial cells are dramatically lost. The surgery involves injecting gas into the anterior chamber of the eye, to create a bubble that pushes onto the donor cornea (graft), achieving sutureless adherence to the host cornea. During the postoperative period, patient positioning affects the bubble. To improve healing, we study the shape of the gas-bubble interface throughout the postoperative period, by numerically solving the equations of fluid motion. Patient-specific anterior chambers (ACs) of variable anterior chamber depths (ACD) are considered, for either phakic (with natural lens) and pseudophakic (with artificial lens) eyes. For each AC, gas-graft coverage is computed for different gas fill and patient positioning. The results show that the influence of positioning is negligible, regardless of gas filling, as long as the ACD is small. However, when the ACD value increases, patient positioning becomes important, especially for pseudophakic ACs. The difference between best and worst patient positioning over time, for each AC, is negligible for small ACD but significant for larger ACD, especially for pseudophakic eyes, where guidelines for optimal positioning become essential. Finally, mapping of the bubble position highlights the importance of patient positioning for an even gas-graft coverage.

Pandemia y atencion ambulatoria pediatrica de alta complejidad en un hospital publico. Experiencia de un modelo de atención con uso de telemedicina en niños/as con nutrición parenteral domiciliaria / Pandemic and highly complex pediatric outpatient care in a public hospital. Experience of a care model with the use of telemedicine in children with home parenteral nutrition

Introducción: Los pacientes que reciben nutrición parenteral domiciliaria (NPD) en seguimiento desde el Hospital requieren un monitoreo que debió modificarse por la pandemia por SARS-CoV-2. Objetivo: Valorar la utilización y el impacto en los resultados, de estrategias alternativas a la atención presencial de pacientes con NPD, empleando telemedicina, durante el inicio de la pandemia por SARS-CoV-2, comparándolas con las prácticas habituales previas. Materiales y métodos: Estudio analítico descriptivo retrospectivo que analizó el monitoreo, la evolución y las complicaciones de pacientes con NPD asistidos en el Hospital en el período previo a la pandemia (1/4/2019 y 31/3/2019) y durante su primer año (1/4/2020 a 31/3/2021), basado en la revisión de historias clínicas y bases de datos de complicaciones. Resultados: Las características demográficas, diagnósticos, procedencia y provisión de la NPD fueron similares en los dos períodos. Durante el período de la pandemia se redujeron en forma significativa el número de controles presenciales y aumentaron los realizados por telemedicina en forma sincrónica (con una modalidad pautada previamente), y los controles por profesionales locales. La participación de los cuidadores en los procedimientos de administración de la NPD aumentó en pandemia. Las tasas de complicaciones, re-internaciones, el número de inicios y suspensiones de tratamiento fueron similares en ambos períodos. Conclusiones: En pandemia fue posible implementar y monitorizar la NPD utilizando telemedicina sin observar afectación significativa de la evolución, las complicaciones de la enfermedad y del tratamiento. El seguimiento mediante telemedicina sincrónica resultó útil y se incorporará como una herramienta más al monitoreo habitual sin reemplazarlo

Introduction: Patients receiving home parenteral nutrition (HPN) under follow-up from the Hospital require monitoring that had to be modified due to the SARSCoV-2 pandemic. Objective: To assess the use and the impact on the results of other care strategies for patients with HPN, using telemedicine, during the beginning of the SARS CoV2 pandemic, compared with previous usual practices.Materials and methods: Retrospective descriptive analytical study that analyzed the monitoring, evolution and complications of patients with HPN assisted in the Hospital, in the period before pandemic ( 4/1/2019 to 3/31/2020) and during the first year of SARS CoV-2 pandemic (4/1/2020 to 3/31/2021), according to data obtained from medical records and databases. Results: demographic characteristics, diagnoses, place of residence and HPN provision were similar in both periods. During the pandemic period, the number of face-to-face controls were significantly reduced and those carried out by telemedicine synchronously, and by local professionals increased. The participation of caregivers in the administration procedures of the HPN increased in the pandemic period. The rates of complications, readmissions, number of initiations and suspensions of home treatment were similar in both periods. Conclusions: It was possible to implement and monitor HPN during pandemic. The evolution and complications of the disease and treatment were not significantly affected. Synchronous telemedicine follow-up was successfully useful and will be incorporated as another tool to regular monitoring

Eculizumab as a promising treatment in thymoma-associated myasthenia gravis.

Myasthenia gravis is a chronic autoimmune disorder caused by antibodies directed against the neuromuscular junction. Some patients may have an associated thymoma, which confers a worse prognosis. Eculizumab, a monoclonal antibody that inhibits the activation of terminal complement, has recently been approved for the treatment of refractory generalized myasthenia gravis. This is an early case report of thymoma-associated refractory myasthenia gravis successfully treated with eculizumab in a real-world setting.

Early electrophysiological findings in Fisher-Bickerstaff syndrome. / Hallazgos electrofisiológicos precoces en síndrome Fisher-Bickerstaff.

INTRODUCTION: The term Fisher-Bickerstaff syndrome (FBS) has been proposed to describe the clinical spectrum encompassing Miller-Fisher syndrome (MFS) and Bickerstaff brainstem encephalitis. The pathophysiology of FBS and the nature of the underlying neuropathy (demyelinating or axonal) are still subject to debate. This study describes the main findings of an early neurophysiological study on 12 patients diagnosed with FBS. PATIENTS AND METHODS: Retrospective evaluation of clinical characteristics and electrophysiological findings of 12 patients with FBS seen in our neurology department within 10 days of disease onset. Follow-up electrophysiological studies were also evaluated, where available. RESULTS: The most frequent electrophysiological finding, present in 5 (42%) patients, was reduced sensory nerve action potential (SNAP) amplitude in one or more nerves. Abnormalities were rarely found in motor neurography, with no signs of demyelination. The cranial nerve exam revealed abnormalities in 3 patients (facial neurography and/or blink reflex test). Three patients showed resolution of SNAP amplitude reduction in serial neurophysiological studies, suggesting the presence of reversible sensory nerve conduction block. Results from cranial MRI scans were normal in all patients. CONCLUSION: An electrophysiological pattern of sensory axonal neuropathy, with no associated signs of demyelination, is an early finding of FBS. Early neurophysiological evaluation and follow-up are essential for diagnosing patients with FBS.

The Anthropocene Generalized: Evolution of Exo-Civilizations and Their Planetary Feedback.

We present a framework for studying generic behaviors possible in the interaction between a resource-harvesting technological civilization (an exo-civilization) and the planetary environment in which it evolves. Using methods from dynamical systems theory, we introduce and analyze a suite of simple equations modeling a population which consumes resources for the purpose of running a technological civilization and the feedback those resources drive on the state of the host planet. The feedbacks can drive the planet away from the initial state the civilization originated in and into domains that are detrimental to its sustainability. Our models conceptualize the problem primarily in terms of feedbacks from the resource use onto the coupled planetary systems. In addition, we also model the population growth advantages gained via the harvesting of these resources. We present three models of increasing complexity: (1) Civilization-planetary interaction with a single resource; (2) Civilization-planetary interaction with two resources each of which has a different level of planetary system feedback; (3) Civilization-planetary interaction with two resources and nonlinear planetary feedback (i.e., runaways). All three models show distinct classes of exo-civilization trajectories. We find smooth entries into long-term, "sustainable" steady states. We also find population booms followed by various levels of "die-off." Finally, we also observe rapid "collapse" trajectories for which the population approaches n = 0. Our results are part of a program for developing an "Astrobiology of the Anthropocene" in which questions of sustainability, centered on the coupled Earth-system, can be seen in their proper astronomical/planetary context. We conclude by discussing the implications of our results for both the coupled Earth system and for the consideration of exo-civilizations across cosmic history. Key Words: Anthropocene-Astrobiology-Civilization-Dynamical system theory-Exoplanets-Population dynamics. Astrobiology 18, 503-518.

The reactivity of cyclopropyl cyanide in titan's atmosphere: a possible pre-biotic mechanism.

Cyclopropyl cyanide and other simple nitriles detected in Titan's atmosphere could be precursors leading to the formation of organic macromolecules in the atmosphere of Saturn's largest satellite. Proposing a thermodynamically possible mechanism that explains their formation and supports experimental results represents a difficult challenge. Experiments done in the Atomic and Molecular Physics Laboratory at the University of Trento (AMPL) have studied the ion-molecule reaction between cyclopropyl cyanide and its protonated form, with reaction products being characterized by mass spectrometry. In addition to the expected ion-molecule adduct stabilized by non-covalent long-range interactions, in this work we prove that another distinct species having the same mass to charge ratio (m/z) of 135 is also produced. Moreover, from a previous study of the neutral cyclopropyl cyanide potential energy surface (PES) which shows a partial biradical character it has been possible to characterize the formation through the bimolecular reaction of a new covalent cyclic organic molecule. Calculations have been carried out at the ab initio Møller-Plesset (MP2) level of theory, ensuring the connectivity of the stationary points by using the intrinsic reaction coordinate (IRC) procedure. In order to characterize the reaction transition state, multireference calculations were done using a complete active space involving six electrons and six molecular orbitals [CAS (6 e-, 6 m.o.)]. This study opens the possibility of exploring the formation of new organic molecules by gaseous phase ion-molecule interaction schemes, with such molecules having relevance in interstellar space and in astrobiology (and may be involved in prebiotic molecular evolution).

Regional point prevalence study of healthcare-associated infections and antimicrobial use in acute care hospitals in Liguria, Italy.

BACKGROUND: Given the importance of monitoring healthcare-associated infections (HCAIs) and the consumption of antibiotics, a regional point prevalence survey was conducted in Liguria between March and April 2016. AIM: To measure the overall prevalence of HCAI and describe the use of antibiotics in all public hospitals. METHODS: Data on risk factors and use of antibiotics were collected for each hospitalized patient. To define the variables significantly associated with HCAI, univariate and multivariate analyses were conducted. Standardized infection ratio and standardized antimicrobial use ratio were measured for each participating hospital. FINDINGS: A total of 3647 patients were enrolled. In all, 429 HCAIs were diagnosed in 376 patients, giving a prevalence of HCAI of 10.3%. Respiratory tract (21.7%) and urinary tract (20%) were the most frequent sites of infection. High rates of meticillin-resistant Staphylococcus aureus (47.4%) and Enterobacteriaceae resistant to carbapenems (26.3%) were isolated. Forty-six percent of patients received at least one antibiotic. Combinations of penicillins including ß-lactamase inhibitors (24.1%) were the most widely used; the main indication (46.7%) was the treatment of a community-acquired infection. CONCLUSION: There was an increase in HCAI prevalence compared to a similar survey conducted in 2007; however, the performance of overlapping investigations will enable more reliable considerations. Nevertheless, data on antimicrobial resistance and use of antibiotics are consistent with the national trend. Despite methodological limitations, prevalence studies are useful to monitor HCAI over time and encourage greater awareness of the problem by all stakeholders.

Substrate interaction defects in histidyl-tRNA synthetase linked to dominant axonal peripheral neuropathy.

Histidyl-tRNA synthetase (HARS) ligates histidine to cognate tRNA molecules, which is required for protein translation. Mutations in HARS cause the dominant axonal peripheral neuropathy Charcot-Marie-Tooth disease type 2W (CMT2W); however, the precise molecular mechanism remains undefined. Here, we investigated three HARS missense mutations associated with CMT2W (p.Tyr330Cys, p.Ser356Asn, and p.Val155Gly). The three mutations localize to the HARS catalytic domain and failed to complement deletion of the yeast ortholog (HTS1). Enzyme kinetics, differential scanning fluorimetry (DSF), and analytical ultracentrifugation (AUC) were employed to assess the effect of these substitutions on primary aminoacylation function and overall dimeric structure. Notably, the p.Tyr330Cys, p.Ser356Asn, and p.Val155Gly HARS substitutions all led to reduced aminoacylation, providing a direct connection between CMT2W-linked HARS mutations and loss of canonical ARS function. While DSF assays revealed that only one of the variants (p.Val155Gly) was less thermally stable relative to wild-type, all three HARS mutants formed stable dimers, as measured by AUC. Our work represents the first biochemical analysis of CMT-associated HARS mutations and underscores how loss of the primary aminoacylation function can contribute to disease pathology.

Multi-chamber microfluidic platform for high-precision skin permeation testing.

The established in vitro tool used for testing the absorption and penetration of chemicals through skin in pharmacology, toxicology and cosmetic science is the static Franz diffusion cell. While widespread, Franz cells are relatively costly, low-throughput and results may suffer from poor reproducibility. Microfluidics has the potential to overcome these drawbacks. In this paper, we present a novel microfluidic skin permeation platform and validate it rigorously against the Franz cell by comparing the transport of 3 model chemicals of varying lipophilicity: caffeine, salicylic acid and testosterone. Permeation experiments through silicone membranes show that the chip yields higher sensitivity in permeant cumulative amounts and comparable or lower coefficients of variation. Using a skin organotypic culture, we show that the chip decreases the effect of unstirred water layers that can occur in static Franz cells. The validation reported herein sets the stage for efficient skin permeation and toxicity screening and further development of microfluidic skin-on-chip devices.

The role of Li+ ions in the gas phase dehydrohalogenation and dehydration reactions of i-C3H7Br and i-C3H7OH molecules studied by radiofrequency-guided ion beam techniques and ab initio methods.

Gas phase reactive collisions between lithium ions and i-C3H7X (X = Br, OH) molecules have been studied under single collision conditions in the center of mass (CM) 0.01-10.00 eV energy range using a radiofrequency-guided ion beam apparatus. Mass spectrometry analysis of the products did show the presence of [C3H6-Li]+, [HX-Li]+, C3H7+, and C2H3+ as well as of the [Li-i-C3H7Br]+ adduct while [Li-i-C3H7OH]+ was hardly detected. For all these reactive processes, the corresponding cross sections have been measured in absolute units as a function of the CM collision energy. Quantum chemistry ab initio calculations done at the second order Möller Plesset level have provided relevant information on the topology of the potential energy surfaces (PESs) where a reaction takes place allowing the characterization of the stationary points on the respective PESs along their reaction pathways. The connectivity of the different stationary points localized on the PESs was ensured by using the intrinsic reaction coordinate (IRC) method, confirming the adiabatic character of the reactions. The main topology features of the reactive PESs, in the absence of dynamical calculations, were used to interpret at the qualitative level the behavior of the experimental excitations functions, evidencing the role played by the potential energy barriers on the experimental dynamics of the reactions. Reaction rate constants at 303.2 K for different reactions have been calculated from measured excitation functions.

A global optimization perspective on molecular clusters.

Although there is a long history behind the idea of chemical structure, this is a key concept that continues to challenge chemists. Chemical structure is fundamental to understanding most of the properties of matter and its knowledge for complex systems requires the use of state-of-the-art techniques, either experimental or theoretical. From the theoretical view point, one needs to establish the interaction potential among the atoms or molecules of the system, which contains all the information regarding the energy landscape, and employ optimization algorithms to discover the relevant stationary points. In particular, global optimization methods are of major importance to search for the low-energy structures of molecular aggregates. We review the application of global optimization techniques to several molecular clusters; some new results are also reported. Emphasis is given to evolutionary algorithms and their application in the study of the microsolvation of alkali-metal and Ca2+ ions with various types of solvents.This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'.

Immunochip analysis identifies novel susceptibility loci in the human leukocyte antigen region for acquired thrombotic thrombocytopenic purpura.

Essentials Genetic predisposition to acquired thrombotic thrombocytopenic purpura (aTTP) is mainly unknown. Genetic risk factors for aTTP were studied by Immunochip analysis and replication study. Human leukocyte antigen (HLA) variant rs6903608 conferred a 2.5-fold higher risk of developing aTTP. rs6903608 and HLA-DQB1*05:03 may explain most of the HLA association signal in aTTP. Click to hear Dr Cataland's presentation on acquired thrombotic thrombocytopenic purpura SUMMARY: Background Acquired thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening thrombotic microangiopathy associated with the development of autoantibodies against the von Willebrand factor-cleaving protease ADAMTS-13. Similarly to what has been found for other autoimmune disorders, there is evidence of a genetic contribution, including the association of the human leukocyte antigen (HLA) class II complex with disease risk. Objective To identify novel genetic risk factors in acquired TTP. Patients/Methods We undertook a case-control genetic association study in 190 European-origin TTP patients and 1255 Italian healthy controls by using the Illumina Immunochip. Replication analysis in 88 Italian cases and 456 controls was performed with single-nucleotide polymorphism (SNP) TaqMan assays. Results and conclusion We identified one common variant (rs6903608) located within the HLA class II locus that was independently associated with acquired TTP at genome-wide significance and conferred a 2.6-fold increased risk of developing a TTP episode (95% confidence interval [CI] 2.02-3.27, P = 1.64 × 10-14 ). We also found five non-HLA variants mapping to chromosomes 2, 6, 8 and X that were suggestively associated with the disease: rs9490550, rs115265285, rs5927472, rs7823314, and rs1334768 (nominal P-values ranging from 1.59 × 10-5 to 7.60 × 10-5 ). Replication analysis confirmed the association of HLA variant rs6903608 with acquired TTP (pooled P = 3.95 × 10-19 ). Imputation of classic HLA genes followed by stepwise conditional analysis revealed that the combination of rs6903608 and HLA-DQB1*05:03 may explain most of the HLA association signal in acquired TTP. Our results refined the association of the HLA class II locus with acquired TTP, confirming its importance in the etiology of this autoimmune disease.

[National consensus on the modified Atkins diet]. / Consenso nacional de dieta Atkins modificada.

INTRODUCTION: Epilepsy is a chronic disease that affects 0.5-1% of the population. One third of the patients become refractory to antiepileptic drugs. Among the non-pharmacological treatments available, the modified Atkins diet is an effective treatment used since 2003 as another alternative for children and adults with refractory epilepsy. DEVELOPMENT: The Ketogenic Diet National Committee, which depends on the Argentine Society of Pediatric Neurology, elaborated this consensus on the modified Atkins diet, basing itself on a review of the literature and on their clinical experience. This consensus in Spanish explains the different aspects to be taken into account regarding the modified Atkins diet, patient selection, implementation, different controls and adverse effects. Unlike the classic ketogenic diet, the modified Atkins diet is initiated without fasting or hospital stay, nor does it require protein, calorie or fluid restriction, thus improving patient palatability and consequently patient tolerability. CONCLUSIONS: The modified Atkins diet is a useful treatment for patients with intractable epilepsy. The publication of this consensus offers the possibility for new centers to get oriented regarding this diet implementation.

TITLE: Consenso nacional de dieta Atkins modificada.Introduccion. La epilepsia es una enfermedad cronica que afecta al 0,5-1% de la poblacion, y un tercio de los pacientes evoluciona hacia una forma refractaria a los farmacos antiepilepticos. Dentro de los tratamientos no farmacologicos disponibles, la dieta cetogenica Atkins modificada es un tratamiento efectivo utilizado desde 2003 como otra alternativa en niños y adultos con epilepsia refractaria. Desarrollo. El Comite Nacional de Dieta Cetogenica, dependiente de la Sociedad Argentina de Neurologia Infantil, elaboro este consenso sobre dieta Atkins modificada basandose en una revision de la bibliografia y en su experiencia clinica. Este consenso explica los distintos aspectos que hay que tener en cuenta sobre la dieta Atkins modificada, eleccion de pacientes, forma de implementacion, diversos controles y efectos adversos. A diferencia de la dieta cetogenica clasica, se inicia sin ayuno ni hospitalizacion, y no hay restriccion proteica, calorica o hidrica, por lo que mejora la palatabilidad y, consecuentemente, la tolerabilidad. Conclusiones. La dieta Atkins modificada es un tratamiento util para pacientes con epilepsia intratable. La publicacion de este consenso ofrece la posibilidad de orientar a nuevos centros en su implementacion.

Consenso nacional de dieta Atkins modificada / National consensus on the modified Atkins diet

Introducción. La epilepsia es una enfermedad crónica que afecta al 0,5-1% de la población, y un tercio de los pacientes evoluciona hacia una forma refractaria a los fármacos antiepilépticos. Dentro de los tratamientos no farmacológicos disponibles, la dieta cetogénica Atkins modificada es un tratamiento efectivo utilizado desde 2003 como otra alternativa en niños y adultos con epilepsia refractaria. Desarrollo. El Comité Nacional de Dieta Cetogénica, dependiente de la Sociedad Argentina de Neurología Infantil, elaboró este consenso sobre dieta Atkins modificada basándose en una revisión de la bibliografía y en su experiencia clínica. Este consenso explica los distintos aspectos que hay que tener en cuenta sobre la dieta Atkins modificada, elección de pacientes, forma de implementación, diversos controles y efectos adversos. A diferencia de la dieta cetogénica clásica, se inicia sin ayuno ni hospitalización, y no hay restricción proteica, calórica o hídrica, por lo que mejora la palatabilidad y, consecuentemente, la tolerabilidad. Conclusiones. La dieta Atkins modificada es un tratamiento útil para pacientes con epilepsia intratable. La publicación de este consenso ofrece la posibilidad de orientar a nuevos centros en su implementación (AU)

Introduction. Epilepsy is a chronic disease that affects 0.5-1% of the population. One third of the patients become refractory to antiepileptic drugs. Among the non-pharmacological treatments available, the modified Atkins diet is an effective treatment used since 2003 as another alternative for children and adults with refractory epilepsy. Development. The Ketogenic Diet National Committee, which depends on the Argentine Society of Pediatric Neurology, elaborated this consensus on the modified Atkins diet, basing itself on a review of the literature and on their clinical experience. This consensus in Spanish explains the different aspects to be taken into account regarding the modified Atkins diet, patient selection, implementation, different controls and adverse effects. Unlike the classic ketogenic diet, the modified Atkins diet is initiated without fasting or hospital stay, nor does it require protein, calorie or fluid restriction, thus improving patient palatability and consequently patient tolerability. Conclusions. The modified Atkins diet is a useful treatment for patients with intractable epilepsy. The publication of this consensus offers the possibility for new centers to get oriented regarding this diet implementation (AU)

Glaucoma detection with damato multifixation campimetry online.

PurposeTo evaluate Damato Multifixation Campimetry Online (DMCO), a free-of-charge internet-based visual field test. DMCO exists in three versions: DMCO BASIC, DMCO STANDARD, and DMCO ADVANCED. The main focus was (i) to investigate the sensitivity and the specificity of the existing DMCO versions in the detection of glaucomatous visual field loss and (ii) to define and evaluate algorithms for the interpretation of DMCO results.MethodsThe study design was an evaluation of a diagnostic test and included 97 individuals performing DMCO and white-on-white perimetry. Interpretation algorithms were devised to define abnormality, and these were evaluated using the Glaucoma Staging System as gold standard. Receiver operating characteristic (ROC) curves and area under the ROC (AUC) were calculated.ResultsAUCs from 15 algorithms ranged from 0.79 to 0.90. The most promising algorithm combined results from two successive DMCO STANDARD tests. The sensitivity was highly dependent on the severity of glaucoma. Hence, for eyes with mild, moderate, advanced, and severe glaucoma, the DMCO test demonstrated a sensitivity of 11.8, 71.4, 100, and 100%, respectively. The specificity was as high as 98.1%. Median duration per eye to complete the DMCO STANDARD test was 86 s for the control group and 125 s in participants with glaucoma.ConclusionsDMCO shows promise as a free-of-charge online tool to identify glaucomatous visual field defects in a preselected population. Ongoing studies are evaluating the use of DMCO in a nonselected population.

Molecular Dynamics Simulations of Small Clusters and Liquid Hydrogen Sulfide at Different Thermodynamic Conditions.

A new force field for the intermolecular H2S-H2S interaction has been used to study the most relevant properties of the hydrogen sulfide system from gaseous to liquid phases by means of molecular dynamics (MD) simulations. In order to check the validity of the interaction formulation, ab initio CCSD(T)/aug-cc-pVTZ calculations, including the counterpoise correction on the H2S, (H2S)2, and (H2S)3 structures optimized at the MP2/aug-cc-pVDZ level, have been performed. The (H2S)2,3 systems have been characterized by performing NVE MD simulations at decreasing values of the temperature, while the liquid sulfide behavior has been investigated considering a NpT ensemble of 512 molecules at several thermodynamic states, defined by different pressure and temperature values. Additional calculations using an ensemble of 2197 molecules at two different temperatures have been performed to investigate the liquid/vapor interface of the system. The S-S, S-H, and H-H radial distribution functions and the coordination number, calculated at the same conditions used in X-ray and neutron diffraction experiments, and the evaluated thermodynamic and structural properties have been compared successfully with experimental data, thus confirming the reliability of the force field formulation and of the MD predictions.

Dehydrohalogenation and Dehydration Reactions of i-C3H7Br and i-C3H7OH by Sodium Ions Studied by Guided Ion Beam Techniques and Quantum Chemical Methods.

Dehydrohalogenation and dehydration reactions of gas-phase i-C3H7Br and i-C3H7OH molecules induced by collision with Na(+), all participants being in their electronic ground state, were studied experimentally in our laboratory using a radiofrequency-guided ion beam apparatus and covering the 0.10-10.00 eV center of mass (CM) energy range. In Na(+) + i-C3H7Br collisions the formation of [C3H6-Na](+) and [HBr-Na](+) by dehydrohalogenation was observed and quantified, as well as that of the ion-molecule adduct [Na-i-C3H7Br](+) together with its decomposition products C3H7(+) and NaBr. In Na(+) + i-C3H7OH collisions the dehydration product [H2O-Na](+) was also found, while [C3H6-Na](+) was hardly detected. Moreover, the [Na-i-C3H7OH](+) adduct formation as well as its decomposition into C3H7(+) and NaOH were also quantified. For all these processes, absolute reaction cross sections were measured as a function of the CM collision energy. From measured excitation functions, rate constants for the formation of [C3H6-Na](+), [HBr-Na](+), and [H2O-Na](+) at 303 K were obtained. Complementing the experiments, exhaustive ab initio structure calculations at the MP2 level of theory were performed, giving information on the most relevant features of the potential energy surfaces (PESs) where the dehydrohalogenation, dehydration, and decomposition reactions take place adiabatically for both collision systems. On these PESs different stationary points associated with potential energy minima and transition state barriers were characterized, and their connectivity was ensured using the intrinsic-reaction-coordinate method. The main topology features of the ab initio calculated PESs allowed a qualitative interpretation of the experimental data also exposing the role of the sodium ion as a catalyst in elimination reactions.

Physical activity, sleep pattern and energy expenditure in double-handed offshore sailing.

AIM: The aim of the present study was to quantify total energy expenditure, activity energy expenditure and time spent at three levels of physical activity (low, moderate, high intensity) in four two-person crews during a 500-mile double-handed sailing regatta. METHODS: Physical activity intensity and energy expenditure were assessed during a 500-nautical-mile double-handed offshore competition in eight male sailors (46.3±3.4 years; 180±13 cm; 85.4±12.5 kg). During the whole regatta, they wore an activity monitor that estimated energy expenditure and minutes spent at each level of intensity (sedentary, <1.5 METs; light physical activity, 1.5-2.9 METs; moderate physical activity, 3.0-6.0 METs; vigorous physical activity, >6.0 METs). RESULTS: The sailors spent longer periods (P<0.0001) of time in sedentary (823±193 min/day) and light physical activities (516±177 min/day) than in moderate (95±34 min/day) or vigorous (6±4 min/day) physical activities. They slept 5 times per day (±1.4) for 36 min (±9) in each sleeping period. The total energy expenditure was 14.26±1.89 MJ/day and the activity energy expenditure was 5.06±1.42 MJ/day. Activity energy expenditure was significantly correlated with total sleep time, boat speed, and distance covered each day (P<0.05). CONCLUSION;:The high total energy expenditure was more likely a consequence of the short and rare periods of sleep during the competition rather than of the bouts of moderate and vigorous physical activities.

Experimental and ab initio studies of the reactive processes in gas phase i-C3H7Br and i-C3H7OH collisions with potassium ions.

Collisions between potassium ions and neutral i-C3H7Br and i-C3H7OH, all in their electronic ground state, have been studied in the 0.10-10.00 eV center of mass (CM) collision energy range, using the radiofrequency-guided ion beam technique. In K(+) + i-C3H7Br collisions KHBr(+) formation was observed and quantified, while the analogous KH2O(+) formation in K(+) + i-C3H7OH was hardly detected. Moreover, formation of the ion-molecule adducts and their decomposition leading to C3H7(+) and either KBr or KOH, respectively, have been observed. For all these processes, absolute cross-sections were measured as a function of the CM collision energy. Ab initio structure calculations at the MP2 level have given information about the potential energy surfaces (PESs) involved. In these, different stationary points have been characterized using the reaction coordinate method, their connectivity being ensured by using the intrinsic-reaction-coordinate method. From the measured excitation function for KHBr(+) formation the corresponding thermal rate constant at 303 K has been calculated. The topology of the calculated PESs allows an interpretation of the main features of the reaction dynamics of both systems, and in particular evidence the important role played by the potential energy wells in controlling the reactivity for the different reaction channels.

Consenso nacional sobre dieta cetogénica / National consensus on the ketogenic diet

Introducción. La epilepsia es una enfermedad crónica que afecta al 0,5-1% de la población, mayormente de inicio durante la infancia. Un tercio de los pacientes evoluciona hacia una forma refractaria al tratamiento con fármacos antiepilépticos, lo que plantea al equipo de salud un desafío terapéutico. La dieta cetogénica (DC) es un tratamiento no farmacológico efectivo utilizado como un método alternativo para el tratamiento de la epilepsia refractaria. Objetivos. Es necesario establecer directrices para utilizar la DC adecuadamente y así expandir su conocimiento y utilización en países hispanoparlantes. El Comité Nacional de Dieta Cetogénica, dependiente de la Sociedad Argentina de Neurología Infantil, elaboró este consenso para estandarizar el uso de la DC basándose en la bibliografía publicada y la experiencia clínica. El grupo está formado por neuropediatras, médicos nutricionistas y licenciadas en nutrición de cinco provincias de Argentina pertenecientes a 10 centros que aplican la DC como tratamiento de la epilepsia refractaria. Desarrollo. Se exponen temas tales como la selección del paciente, el asesoramiento a la familia antes del tratamiento, las interacciones de la DC con la medicación anticonvulsionante, los suplementos, el control de efectos adversos y la retirada de dicha dieta. Conclusiones. La DC es un tratamiento útil para los pacientes pediátricos con epilepsia intratable. Es fundamental la educación y colaboración del paciente y la familia. El tratamiento debe llevarlo a cabo un equipo interdisciplinar experimentado, siguiendo un protocolo. La formación de un grupo nacional interdisciplinar, y la publicación de este consenso, ofrece la posibilidad de orientar a nuevos centros en su implantación (AU)

Introduction. Epilepsy is a chronic disease with onset in infancy affecting 0.5-1% of the population. One third of the patients is refractory to antiepileptic drugs and they pose a challenge for the health care team. The ketogenic diet is an effective, non-pharmacological, alternative treatment for the management of refractory epilepsy. Aims. There is a need to establish guidelines for the adequate and increased use of the ketogenic diet in Spanish-speaking countries. The National Committee on the Ketogenic Diet, consisting of paediatric neurologists, clinical nutritionists, and dietitians, of the Argentine Society of Child Neurology has developed this consensus statement to standardize the use of the ketogenic diet based on the literature and clinical experience. Development. Patient selection, pre-treatment family counseling, drug interactions, micronutrient supplementation, adverse effects, and discontinuation of the diet are discussed. Conclusions. The ketogenic diet is an effective treatment for children with refractory epilepsy. Education and collaboration of the patient and their family is essential. The patient should be managed by an experienced multidisciplinary team using a protocol. The formation of a national multidisciplinary team and the publication of this document provide possibilities for new centers to integrate the ketogenic diet into their treatment options (AU)