Uncoupling system and environment simulation cells for fast-scaling modeling of complex continuum embeddings.

Continuum solvation models are becoming increasingly relevant in condensed matter simulations, allowing to characterize materials interfaces in the presence of wet electrified environments at a reduced computational cost with respect to all atomistic simulations. However, some challenges with the implementation of these models in plane-wave simulation packages still persists, especially when the goal is to simulate complex and heterogeneous environments. Among these challenges is the computational cost associated with large heterogeneous environments, which in plane-wave simulations has a direct effect on the basis-set size and, as a result, on the cost of the electronic structure calculation. Moreover, the use of periodic simulation cells is not well-suited for modeling systems embedded in semi-infinite media, which is often the case in continuum solvation models. To address these challenges, we present the implementation of a double-cell formalism, in which the simulation cell used for the continuum environment is uncoupled from the one used for the electronic-structure simulation of the quantum-mechanical system. This allows for a larger simulation cell to be used for the environment, without significantly increasing computational time. In this work, we show how the double-cell formalism can be used as an effective periodic boundary conditions correction scheme for nonperiodic and partially periodic systems. The accuracy of the double-cell formalism is tested using representative examples with different dimensionalities, both in vacuum and in a homogeneous continuum dielectric environment. Fast convergence and good speedups are observed for all the simulation setups, provided the quantum-mechanical simulation cell is chosen to completely fit the electronic density of the system.

EUS-guided tissue samples for the diagnosis of patients with a thickened gastric wall and prior negative endoscopic biopsies.

AIM: Evaluate the diagnostic yield of biopsies obtained by EUS guidance in patients with gastric wall thickening and prior negative endoscopic biopsies. MATERIAL AND METHODS: Data collected from October 2008 to January 2016 were analyzed in a retrospective manner. All included patients had undergone at least one endoscopy with a negative biopsy and showed evidence of gastric wall thickening by tomography, confirmed by endoscopy. All patients gave their written informed consent before the procedure. Demographics and baseline characteristics, including age, sex, number of previous endoscopies, and histopathological diagnosis were recorded. Follow-up data were obtained from a review of the electronic medical records. RESULT: In total, 22 patients with previous negative endoscopic biopsies and gastric wall thickening were included. Using EUSFNA/FNB, the diagnosis was made in the first procedure in 19/22 (86.30%) cases, while in 1/22 (4.5%) patients the diagnosis was made in the second EUS-FNA. A total of 18 (81.82%) patients with EUS-FNA were assessed using a standard Echo-tip, while the remaining four (18.18%) patients underwent EUS-FNB and using a ProCore needle. All patients with a final diagnosis of malignancy had a thickened gastric wall with impaired gastric distension and a loss of wall structure determined by EUS. Of patients with a benign final diagnosis, all (n=8) showed a thickened gastric wall by EUS but with preservation of the deep layers. CONCLUSION: EUS-FNA/FNB is necessary in patients with a thickened gastric wall and prior negative biopsy on endoscopy. The procedure is safe and has a good diagnostic.

Array of biosensors for discrimination of grapes according to grape variety, vintage and ripeness.

A bioelectronic tongue based on nanostructured biosensors specific for the simultaneous detection of sugars and phenols has been developed. The array combined oxidases and dehydrogenases immobilized on a lipidic layer prepared using the Langmuir-Blodgett technique where Glucose oxidase, d-Fructose dehydrogenase, Tyrosinase or Laccase were imbibed. A phthalocyanine was co-immobilized in the sensing layer and used as electron mediator. The array thus formed has been used to analyze grapes and provides global information about the samples while providing specific information about their phenolic and their sugar content. Using Principal Component Analysis (PCA) the array of voltammetric biosensors has been successfully used to discriminate musts prepared from different varieties of grapes (Tempranillo, Garnacha, Cabernet-Sauvignon, Prieto Picudo and Mencía). Differences could be also detected between grapes of the same variety and cultivar harvested in two successive vintages (2012 and 2013). Moreover, the ripening of grapes could be monitored from veraison to maturity due to the changes in their phenolic and sugar content. Using Partial Least Squares (PLS-1) analysis, excellent correlations have been found between the responses provided by the array of biosensors and classical parameters directly related to phenols (total polyphenol index, TPI) and sugar concentration (degree Brix) measured by chemical methods with correlation coefficients close to 1 and errors close to 0. It is also worthy to notice the good correlations found with parameters associated with the pH and acidity that can be explained by taking into account the influence of the pH in the oxidation potentials of the phenols and in the enzymatic activity. This bioelectronic tongue can assess simultaneously the sugar and the phenolic content of grapes and could be used to monitor the maturity of the fruit and could be adapted easily to field analysis.

Characterization of textile electrodes and conductors using standardized measurement setups.

Textile electrodes and conductors are being developed and used in different monitoring scenarios, such as ECG or bioimpedance spectroscopy measurements. Compared to standard materials, conductive textile materials offer improved wearing comfort and enable long-term measurements. Unfortunately, the development and investigation of such materials often suffers from the non-reproducibility of the test scenarios. For example, the materials are generally tested on human skin which is difficult since the properties of human skin differ for each person and can change within hours. This study presents two test setups which offer reproducible measurement procedures for the systematic analysis of textile electrodes and conductors. The electrode test setup was designed with a special skin dummy which allows investigation of not only the electrical properties of textile electrodes but also the contact behavior between electrode and skin. Using both test setups, eight textile electrodes and five textile conductors were analyzed and compared.

Monitoring change of body fluids during physical exercise using bioimpedance spectroscopy.

During physical exercise body muscles are activated and heat is generated. In intensive physical activity, heat will be released by sweating to protect the body of overheating. Sweating and convection implies a water loss which can lead to dehydration. To avoid health problems as a result of dehydration, the body water content can be monitored to detect changes early in order to rehydrate in time. Bioimpedance Spectroscopy (BIS) is a comfortable measurement method to monitor the body composition under controlled conditions, that is used for different applications, like monitoring dialysis. Unfortunately, the physiological changes due to sportive activities can influence the BIS and complicate the measurement. In this article, a study is presented in which the fluid content of five test persons is monitored during physical exercise, whereas all test persons did not drink anything before and during sport. During training not only the body composition was measured using a BIS device but also the skin temperature was monitored with an infrared camera. As a result, it could be shown that such a combination of measurement systems allow to use BIS devices also during sport as significant monitoring systems for detecting a person's body fluid loss.

Modeling the influence of body position in bioimpedance measurements.

Bioimpedance Spectroscopy (BIS) enables the determination of the human body composition (e.g. fat content, water content). From this data, it is possible to draw conclusions about the person's health state. This technology can be easily implemented combined with low costs, which could be used for an easy use at home with a reliable accuracy. Nevertheless, external factors such as body position influence the measurements, limiting their accuracy and use. The use of modeling of these external factors and their influence on the body could be used to improve the accuracy of the bioimpedance spectroscopy and to extend it for a continuous monitoring. In this paper the results of the modeling of the body position for a localized bioimpedance measurement (thigh) and a comparison with measurements on 5 subjects lying down for 40 minutes are shown and discussed.

Manifestaciones eléctricas de alteraciones miocárdicas asociadas a preexcitación ventricular / On the electrical manifestations of some heart diseases associated with ventricular preexcitation

Electro-Vectorcardiographic curves, corresponding some heart diseases, must be analyzed in the light of the ventricular depolarization sequence, as well as on the heart's position and rotation. A more than 30-msec interval between the end of the initial slurring (delta) and the vertex of the R wave in the left unipolar leads or the main axis of the vectorcardiographic ventricular curves, allows us to infer the coexistence of left ventricular hypertrophy. On the other hand, segmental irregularities or distorsions of the electric curves suggest the presence of a limited myocardial zone unable to be activated. Extensive or multiple deformations of these curves are more suggestive of a diffuse myocardial damage. Sometimes signs of preexcitation, due to a pharmacological action, can also appear.

Administración de vacunas y casos de muerte súbita del lactante en el Perú, 2001. ¿Asociación o coincidencia temporal? / Immunization and sudden death in infants in Peru, 2001. Is it an association or a temporary coincidence?

Objetivos: Describir las características clínicas, socioeconómicas, y patológicas de nueve casos de lactantes que fallecieron horas después de administrárseles vacunas antipolio y DPT junto con anti Haemophilus influenzae b o asociada con antihepatitis B o BCG. Materiales y métodos: Revisión de la historia clínica, entrevista con el equipo de salud a cargo de la vacunación y con los padres del lactante fallecido. Revisión de los informes del protocolo de autopsia e informes de anatomía patológica y entrevista con los médicos legistas y patólogos. Evaluación de controlde calidad de las vacunas administradas. Realización de exámenes de inmunohistoquímica de tejidos pulmonarespara el diagnóstico de virus. Resultados: Entre agosto y diciembre de 2001 se notificaron en el Perú, nueve casos de fallecimiento de lactantes entre ocho horas y tres días después de la aplicación de vacunas DPT y antipolio. Después de la vacunación, los síntomas iniciaron entre 30 minutos a tres horas y la muerte se produjo entre ocho a 78 horas. Los síntomas más frecuentes fueron irritabilidad 8/9, llanto persistente 6/9, somnolencia 5/9, sangrado por nariz y boca5/9. Todos los casos procedieron de familias pobres o muy pobres. El control de calidad se corroboró que las vacunas cumplieron con los estándares establecidos por la OMS. Las causas de la muerte reportadas en las necropsias fueron neumonía en dos casos y edema pulmonar en cinco casos, los informes de anatomía patológica mostraron una neumonitis intersticial y meningitis linfocitaria. No se observaron efectos citopáticos virales en los tejidos pulmonares y los estudios toxicológicos fueron negativos. Conclusiones: No existe evidencia de una asociación causal entre los eventosfatales y la administración de las vacunas.

Objectives: To describe clinical, socio-economic, and pathological characteristics of nine infants who died hours after receiving anti-polio and DPT vaccines, together with anti-Haemophilus influenzae b or in association to anti-hepatitis B vaccine or BCG. Materials and methods: Review of the clinical record, interview with the healthcare team in charge of immunization, and with parents of the deceased infant. Review the autopsy and pathology reports, as well as an interview with pathologists and forensic physicians. Quality control assessment of vaccines used immunohistochemistry examinations for virus diagnosis. Results: Between August and December 2001, nine cases of infant death were reported in Peru, between 8 hours and 3 days after receiving DPT and anti-polio vaccines. After immunization, symptoms appeared from thirty minutes to three hours, and death occurred between 8 to 78 hours. Most frequently reported symptoms were: irritability (8/9), persistent weeping (6/9), somnolence (5/9), nose and mouth bleeding (5/9). All cases occurred in poor or very poor families. Quality control assessments corroborated that vaccines complied with standards set by the World Health Organization. Causes of death reported in autopsies were pneumonia in 2 cases and pulmonary edema in 5 cases; pathology reports indicated the presence of interstitial pneumonitis and lymphocyte meningitis. No viral cytopathic effects in pulmonary tissues were found, and toxicological studies were reported as negative. Conclusions: There is no evidence of a causal relationship between fatal events and vaccine administration.

[Usefulness of vector analysis of the electrocardiogram]. / Utilidad del análisis vectorial del electrocardiograma.

An electrocardiogram corresponding to an obese, hypertensive woman 52 years old, is presented. It shows a left bundle branch block of advanced degree and the AQRSF at 70 degrees. In this case, the key of the electrocardiographic diagnosis is that the second vector originated by depolarization of the lower left septal mass is oriented downward, which is unusual in the presence of left bundle branch block. This fact may be due to a marked clockwise rotation. Therefore, it is possible that right ventricle pathologic conditions be associated to those involving the left ventricle. Cardiopulmonary tests determined the existence of a chronic pulmonary emphysema. Furthermore the study of this case shows the usefulness of vectorcardiographic exploration in clinical practice.

The rational approach to the electrical exploration of the heart.

A rational approach is inevitable in any scientific activity. Such an approach is opposed not only to irrationality, at all inadmissible in scientific thinking, but also to empiric reasoning. Many years ago, Sodi Pallares introduced the rational method in the electrical exploration of the heart based on experimental findings obtained in his laboratory. This method has progressively been accepted and used with good results for diagnoses and has led to logical therapeutic inferences. To confirm the results from the logical interpretation of electrical tracings, we present some examples of its application in three fields: arrhythmias, myocardial infarction, and left ventricular hypertrophy. In the studied cases--two with tachycardia, one with a posterior infarct, and two with left ventricular hypertrophy--a very satisfactory correlation has been observed between the electrical exploration findings and those obtained through direct examination of the heart. It is desirable, and even profitable, to analyze in this way the electrical tracings to get as close as possible to reality, rejecting the stereotyped aspects of a simple routine exploration, which often induce errors and lead to some fallacious asseverations.

[Rational electrovectorcardiography]. / En torno a la electrovectocardiografía racional.

The mental process of electrocardiographists to adjust the electrocardiogram's or vectorcardiogram's interpretation with the sequence of myocardial depolarization and repolarization can be accomplished in two ways. The first one is through vectorial analysis and the second concerns the analysis of unipolar morphologies. The most suitable is to follow both ways. The first procedure constitutes the classic method accepted since Einthoven's time and refers to the vectorial representation of the electrical charges of the heart. This representation approaches the electrical moment of a unique dipole, when cardiac exploration is performed at the smallest adequate distance. This allows to establish the spatial position of the instantaneous vectors, or of the mean vector, by using different leads. The study of unipolar morphologies permits to know the distribution of the mentioned charges in the conducting medium. The adjustment of the electrical charges depends on the location of the wave fronts. These charges produce potential variations in the physical sense--Gaussian type--at the epicardial surface and also at any point of the conducting medium surrounding the heart as far as the skin. This procedure requires the use of Poisson's integral, based on the principle of Helmholtz' electromotive surface. Thereafter, it is mandatory to perform another adjustment for the results of both procedures and to scrutinize the inner cellular metabolic process, which can explain the behavior of the observed electrical phenomena and suggest the adequate treatment.

On the electrocardiographic diagnosis of biventricular infarctions.

To diagnose posterior and anterior biventricular infarctions it is necessary to record from right and left thoracic and high abdominal unipolar leads. These supplementary leads are dependable, can be repeated as many times as needed and show the evolution from signs of myocardial injury to those of dead tissue (Q waves of 0.04 sec or more). This electrocardiographic evolution increases the diagnostic value of the electrical exploration, since the injury current can be observed also in other conditions. The diagnosis of right ventricular infarction can be established even in the presence of RBBB. Signs of a dead zone in the free right ventricular wall are more frequently observed in posterior biventricular infarctions than in anterior ones. In these cases, the signs of subepicardial injury are more accentuated in the right thoracic unipolar leads than in V3, indicating anterior right ventricular involvement. These signs are also observed in experimental studies made in animals. This electrocardiographic exploration opens a wide field for the diagnosis of myocardial infarction, particularly in biventricular involvement, including old myocardial scars, and in discarding signs of pericarditis manifested only by the upward displacement of the ST segment. A review of the medical literature concerning diagnosis of biventricular infarctions is presented.

[Is the concept of "jumping wave" still valid?]. / Es aún válido el concepto de "salto de onda"?

UNLABELLED: The concept of the "jumping wave" phenomenon, i.e. of the slow and difficult passage of activation fronts from one septal mass to the other through an "intraseptal barrier", is derived from experimental studies of the Mexican School of Electrovectorcardiography. OBJECTIVE: To confirm the existence of histologically bipartite interventricular septum and of the electric independence of both septal masses. METHODOLOGY: We examined the histological characteristics of both septal masses in rat, canine, and human hearts. We also analyzed the morphological and chronological data of intracavitary records in the presence of different degree proximal blocks, comparing these findings with those obtained when peripheral blocks existed. RESULTS: We found a medial, longitudinal band between the two septal masses in animal as well as in human hearts. The analysis of intracavitary electric records confirmed a slow and difficult transmission of the activation fronts from one septal mass to the other, in the presence of proximal blocks and ventricular arrhythmias. Morphological and chronological changes of intraventricular complexes could not be explained if the septal activation process were of syncytial type. CONCLUSIONS: Results of this study firmly support the validity of our approach to the septal activation process in the presence of ventricular conduction disorders and arrhythmias. This approach helps to detect the possible coexistence of dead septal tissue.

Consenso Latinoamericano sobre infecciones en bronquitis crónica / Latin American consensus on infections in chronic bronchitis

Dos tercios de las exacerbaciones agudas de la bronquitis crónica (EABC) se asocian con infección bacteriana y se caracterizan por recrudecimiento súbito de la tos, disnea y aumento en el volumen y el aspecto purulento del esputo. Las infecciones bacterianas crónicas o recurrentes, inician y perpetúan un círculo vicioso de daño a las vías aéreas, que se produce mediante la estimulación persistente de la cascada inflamatoria por los productos bacterianos. De los microorganismos causales, el más común es H. influenzae. Otros patógenos frecuentes incluyen M. catarrhalis, la mayoría resistentes a aminopenicilinas y S. Pneumoniae, el cual ha incrementado recientemente a su resistencia a penicilinas y macrólidos a nivel orbital. Si bien algunos estudios recientes han demostrado de manera clara el beneficio del tratamiento antibiótico de los EABC, existen ciertas dudas relacionadas con la manera de clasificar la enfermedad y con los criterios utilizados para la inclusión y exclusión de los pacientes, que permitan esclarecer de manera definitiva el beneficio del antimicrobiano en cada uno de los grupos en los que se ha clasificado su severidad. Con el fin de lograr un consenso sobre algunas de estas variables y establecer lineamientos racionales que permitan abordar el tratamiento de estos pacientes, se reunieron recientemente (noviembre del 96 y marzo del 97) un grupo de destacados expertos latinoamericanos en infectología y neumología. El consenso identificó una serie de factores de riesgo que permitieron diseñar una clasificación de EABC que establece cuatro grados de severidad; estos a su vez están relacionados con un grupo específico de microorganismos que varían con las circunstancias y desde luego en la sensibilidad a los antibióticos. Asimismo el grupo de expertos estableció que la resistencia de los gérmenes que comúnmente afectan a estos enfermos (H. influenzae, S. pneumoniae y M. catarrhalis) requieren de antimicrobianos que sean activos contra más del 90 por ciento de las cepas causantes. Como lineamientos prácticos terapéuticos, se sugirió que la traqueobronquitis aguda (clase I) no requiere en general de antibióticos; que la amoxicilina permanece como el tratamiento de elección para las exacerbaciones leves (clase II), mientras que para la bronquitis crónica complicada (clase III), algunas fluoroquinolonas (p.ej.: ciprofloxacina), los nuevos macrólidos, combinaciones con inhibidores de betalactamasa o cefalosporina orales de 3º generación...

Consenso Latino-Americano sobre infecçöes em bronquite crônica / Guidelines for the role of antibiotics in acute exacerbations of chronic bronchitis in Latin America

Infecçöes bacterianas crônicas ou de repetiçäo däo início e perpetuam o ciclo vicioso de lesäo das vias aéreas através da estimulaçäo dos mecanismos inflamatórios, desencadeada pelos produtos bacterianos e pela invasäo bacteriana recorrente. As exacerbaçöes agudas de bronquite crônica(EABC) säo caracterizadas por quadro abrupto de tosse,aumento da dispnéia e aumento no volume de escarro produzido. Em dois terços ou mais dos casos típicos de EABC säo isolados patógenos bacterianos. O patógeno predominante é o H. influenzae, o qual se encontra nitidamente associado ao círculo vicioso de inflamaçäo e infecçäo de repetiçäo. Entre outros patógenos comumente encontrados se incluem Moraxella catarrhalis, muitas das quais resistentes às aminopenicilinas devido à produçäo de ß-lactamase e, também, Streptococcus pneumoniae, em relaçäo aos quais se tem observado aumento no número de cepas resistentes à penicilina e macrolídeos, em âmbito mundial...

Effects of verapamil in ventricular tachycardias. An experimental and clinical study.

To determine the effect of verapamil in ventricular tachycardias, we performed an experimental and clinical study. Experimental ventricular tachycardias (VT) were produced in dog hearts with minute aconitine crystals introduced into the periphery of a left ventricular area, damaged by intramural injection of 1.0-1.5 ml phenol. The response of these tachycardias to 0.2 mg/kg verapamil was analyzed. Verapamil was infused into the superior vena cava over 15-20 min. Leads II, aVL, intraventricular right and left unipolar records, as well as one of the superior vena cava, were registered under control conditions, in the presence of VT, and after application of verapamil. Recordings were obtained at constant intervals, waiting for the recovery of sinus rhythm (SR) and the posterior reappearance of tachycardia. Experiments were performed for 6 to 8 h under continuous infusion of Hartmann's solution. Throughout these periods, variations in systemic systolic pressure were recorded. From 75 animals submitted to this treatment, 30 (40%) recovered transiently the SR, whereas the drug exerted no antiarrhythmic effect in 19 (25%), and arterial systolic pressure fell importantly in 10 (13%) animals. In two more groups, of 15 dogs each, the VT response to verapamil was compared with the response to lidocaine and flecainide. Endovenous verapamil (5-10 mg) was administered to 10 patients, coursing with VT and having a structurally normal heart, after this arrhythmia was induced by electrical stimulation. The response to verapamil was satisfactory in nine patients (90%), in which VT originated in the septal and apical regions of the left ventricle. Verapamil seems to be effective in experimental and clinical ventricular tachycardias related to calcium-dependent potentials, in which the sustaining mechanism could either be triggered activity or reentry.