The study of functional reorganization following stroke has been steadily growing supported by advances in neuroimaging techniques, such as functional magnetic resonance imaging (fMRI). Concomitantly, graph theory has been increasingly employed in neuroscience to model the brain's functional connectivity (FC) and to investigate it in a variety of contexts. The aims of this study were: 1) to investigate the reorganization of network topology in the ipsilesional (IL) and contralesional (CL) hemispheres of stroke patients with (motor stroke group) and without (control stroke group) motor impairment, and 2) to predict motor recovery through the relationship between local topological variations of the functional network and increased motor function. We modeled the brain's FC as a graph using fMRI data, and we characterized its interactions with the following graph metrics: degree, clustering coefficient, characteristic path length, and betweenness centrality (BC). For both patient groups, BC yielded the largest variations between the two analyzed time points, especially in the motor stroke group. This group presented significant correlations (P<0.05) between average BC changes and the improvements in upper-extremity Fugl-Meyer (UE-FM) scores at the primary sensorimotor cortex and the supplementary motor area for the CL hemisphere. These regions participate in processes related to the selection, planning, and execution of movement. Generally, higher increases in average BC over these areas were related to larger improvements in UE-FM assessment. Although the sample was small, these results suggest the possibility of using BC as an indication of brain plasticity mechanisms following stroke.

Staphylococcus aureus se presenta como un patógeno cada vez más importante, debido al arsenal de factores de virulencia que presenta, sumado a su elevada capacidad de generar resistencia a los antimicrobianos Los objetivos de esta investigación fueron: confirmar la resistencia a meticilina mediante la amplificación del gen mecA y detectar la presencia de los genes que codifican el factor de virulencia leucocidina de Panton Valentine (PVL). Se investigaron estos genes empleando la reacción en cadena de polimerasa (PCR). Todos los aislamientos presentaron el gen mecA, el 50% de estas cepas resultó portador del gen para PVL. El 54,17% de las muestras de pacientes pediátricos, dio positivo para esta leucocidina. El mayor porcentaje de aislamiento se encontró en muestras de piel y tejidos blandos (85,7%).

Staphylococcus aureus is an increasingly important pathogen, due to the arsenal of virulence factors which presents, in addition to its high capacity to generate antimicrobial resistance. The objectives of this research were: confirm methicillin resistance by amplification the mecA gene and the presence of genes that encode Panton Valentine leucocidin (PVL) virulence factor. These genes have been investigated using polymerase chain reaction (PCR). All isolates showed the mecA gene, 50% of these strains were carrying the gene for PVL. 54,17% of the samples from pediatric patients, yield positive for this leukocidin. The highest percentage of isolation was found in samples of skin and soft tissues (85.7%).

Algunas especies de Aeromonas han emergido como patógenos importantes, asociadas al desarrollo de infecciones gastrointestinales y extraintestinales. El objetivo de este estudio fue evaluar el potencial de virulencia de cepas de Aeromonas procedentes de vegetales. Se analizó los factores de virulencia: DNAsa, lecitinasa, caseinasa, gelatinasa, β-hemolisinas y hemaglutininas, en 59 cepas de A. hydrophila y 61 de A. caviae, aisladas de cilantro, perejil y lechuga, comercializados en Maracaibo. Los resultados fueron analizados mediante el estadístico χ². Los factores de virulencia estudiados fueron expresados por más del 80% de las cepas. Cuatro de los 6 factores fueron expresados en mayor proporción por las cepas de A. hydrophila, aunque la diferencia entre las especies sólo resultó significativa para la expresión de caseinasa (94,9% vs 72,1% p<0,05). Todas las cepas exhibieron actividad de DNAsa. La expresión de lecitinasa resultó ligeramente superior en las cepas de A. caviae (p > 0,05). Se evidenció una diferencia significativa en el número de factores de virulencia expresado por las dos especies, siendo mayor para A. hydrophila (p < 0,05). La expresión de un número elevado de factores de virulencia por las cepas de Aeromonas analizadas, permite atribuirles un potencial de patogenicidad similar al descrito en las cepas procedentes de infecciones humanas.

Some species of Aeromonas have emerged as important pathogens associated with the development of gastrointestinal and extra-intestinal infections. The objective of this study was to evaluate the potential virulence of Aeromonas strains from vegetables. Virulence factors were analyzed: DNase, lecitinasa, caseinase, gelatinase, hemolysines and hemaglutinies, in 59 strains of A. hydrophila and 61 of A. caviae, isolated from coriander, parsley and lettuce obtained in establishments in Maracaibo city. The results were analyzed through statistics χ2. The virulence factors studied were expressed for more of the 80% of the strains. Four of the 6 factors were expressed in greater proportion in Aeromonas hydrophila strains, although the difference between the species only significant in for caseinase expression (94.9% vs 72.1%, p <0.05). All strains exhibited DNase activity. The lecitinasa expression result slightly higher in A. caviae strains (p> 0.05). A significant difference was evident in the number of virulence factors expressed by the two species, being higher for A. hydrophila (p <0.05). The expression of a large number of virulence factors the analyzed Aeromonas strains, allow to attribute a potential of pathogenicity to the strain of human infections.

S. aureus se ha convertido en un problema de salud pública, debido a la dificultad que representa el tratamiento de las infecciones causadas por SARM. El propósito de esta investigación fue determinar la producción de enterotoxinas A, B, C y D y la producción de biofilm en aislamientos de SARM. Se estudiaron 50 cepas aisladas de diferentes tipos de muestras clínicas. La detección de enterotoxinas se realizó por la técnica de aglutinación en fase reversa y la producción de biofilm mediante: agar rojo congo y el método en microplacas de cultivos celulares. La producción de enterotoxina se observó en 9 cepas (18%), siendo la enterotoxina D (64%) la más prevalente, seguida de la B (27%) y la A (9%). Se demostró una asociación significativa entre la producción de enterotoxina y el tipo de muestra de la que provenía la cepa. La producción de biofilm se constató en 30% y 98% de las cepas por los métodos de agar rojo congo y microplacas de cultivos celulares, respectivamente; sólo en 15 cepas (30%) se observó correlación de ambos ensayos, se demostró que el método en microplacas de cultivo celular es más eficaz para detectar la producción de biofilm en S. aureus.

S. aureus has become a public health problem, due to the difficulty of treating infections caused by methicillin-resistant S. aureus (MRSA). The purpose of this research was to determine the production of enterotoxins A, B, C and D and the production of biofilm in clinical isolates of MRSA. Fifty MRSA strains isolated from different types of clinical samples were studied. Detection of enterotoxins was carried out using the technique of reversed phase agglutination, while biofilm production was studied through two tests: Congo red agar and the microplate cell culture method. Enterotoxin production was observed in 9 strains (18%); enterotoxin D (64%) was the most prevalent, followed by B (27%) and A (9%). A significant association was shown between enterotoxin production capacity and the type of sample that came from the strain. Biofilm production was found in 30% and 98% of the strains using the Congo red Agar and microplate cell culture methods, respectively. A correlation of both trials was observed in only 15 strains (30%). It was shown that the microplate cell culture method is more effective for detecting biofilm production in S. aureus strains.

Discutimos inicialmente a validade do intervalo de tempo fornecido por uma fórmula encontrada na literatura, que dá a distância percorrida em função do tempo para um líquido que sobe num tubo capilar. Um ajuste não linear de mínimos quadrados dos dados experimentais com essa fórmula permite a medida da viscosidade cinética do fluido. A qualidade do ajuste para dois conjuntos de dados experimentais daliteraura é acima de 99%.

We discuss first the valid time interval of a formula found in the literature which gives the theoretical distance run by a liquid which rises along a capillary tube as a function of time. A non-linear least square fitting of experimental data to this theoretical curve allows the measurement of the kinematic viscosity of the liquid. The goodness of the fitting for three different sets of experimental data given in the literature is above 99%.

Huntington's disease (HD) is a neurologic disorder that is not completely understood; its fundamental physiological mechanisms and chemical effects remain somewhat unclear. Among these uncertainties, we can highlight information about the concentrations of brain metabolites, which have been widely discussed. Concentration differences in affected, compared to healthy, individuals could lead to the development of useful tools for evaluating the progression of disease, or to the advance of investigations of different/alternative treatments. The aim of this study was to compare the thalamic concentration of metabolites in HD patients and healthy individuals using magnetic resonance spectroscopy. We used a 2.0-Tesla magnetic field, repetition time of 1500 ms, and echo time of 135 ms. Spectra from 40 adult HD patients and 26 control subjects were compared. Quantitative analysis was performed using the LCModel method. There were statistically significant differences between HD patients and controls in the concentrations ofN-acetylaspartate+N-acetylaspartylglutamate (NAA+NAAG; t-test, P<0.001), and glycerophosphocholine+phosphocholine (GPC+PCh;t-test, P=0.001) relative to creatine+phosphocreatine (Cr+PCr). The NAA+NAAG/Cr+PCr ratio was decreased by 9% and GPC+PCh/Cr+PCr increased by 17% in patients compared with controls. There were no correlations between the concentration ratios and clinical features. Although these results could be caused by T1 and T2 changes, rather than variations in metabolite concentrations given the short repetition time and long echo time values used, our findings point to thalamic dysfunction, corroborating prior evidence.

N-acetyl-aspartyl-glutamate (NAAG) and its hydrolysis product N-acetyl-L-aspartate (NAA) are among the most important brain metabolites. NAA is a marker of neuron integrity and viability, while NAAG modulates glutamate release and may have a role in neuroprotection and synaptic plasticity. Investigating on a quantitative basis the role of these metabolites in brain metabolism in vivo by magnetic resonance spectroscopy (MRS) is a major challenge since the main signals of NAA and NAAG largely overlap. This is a preliminary study in which we evaluated NAA and NAAG changes during a visual stimulation experiment using functional MRS. The paradigm used consisted of a rest period (5 min and 20 s), followed by a stimulation period (10 min and 40 s) and another rest period (10 min and 40 s). MRS from 17 healthy subjects were acquired at 3T with TR/TE = 2000/288 ms. Spectra were averaged over subjects and quantified with LCModel. The main outcomes were that NAA concentration decreased by about 20% with the stimulus, while the concentration of NAAG concomitantly increased by about 200%. Such variations fall into models for the energy metabolism underlying neuronal activation that point to NAAG as being responsible for the hyperemic vascular response that causes the BOLD signal. They also agree with the fact that NAAG and NAA are present in the brain at a ratio of about 1:10, and with the fact that the only known metabolic pathway for NAAG synthesis is from NAA and glutamate.

In vivo proton magnetic resonance spectroscopy (¹H-MRS) is a technique capable of assessing biochemical content and pathways in normal and pathological tissue. In the brain, ¹H-MRS complements the information given by magnetic resonance images. The main goal of the present study was to assess the accuracy of ¹H-MRS for the classification of brain tumors in a pilot study comparing results obtained by manual and semi-automatic quantification of metabolites. In vivo single-voxel ¹H-MRS was performed in 24 control subjects and 26 patients with brain neoplasms that included meningiomas, high-grade neuroglial tumors and pilocytic astrocytomas. Seven metabolite groups (lactate, lipids, N-acetyl-aspartate, glutamate and glutamine group, total creatine, total choline, myo-inositol) were evaluated in all spectra by two methods: a manual one consisting of integration of manually defined peak areas, and the advanced method for accurate, robust and efficient spectral fitting (AMARES), a semi-automatic quantification method implemented in the jMRUI software. Statistical methods included discriminant analysis and the leave-one-out cross-validation method. Both manual and semi-automatic analyses detected differences in metabolite content between tumor groups and controls (P < 0.005). The classification accuracy obtained with the manual method was 75% for high-grade neuroglial tumors, 55% for meningiomas and 56% for pilocytic astrocytomas, while for the semi-automatic method it was 78, 70, and 98%, respectively. Both methods classified all control subjects correctly. The study demonstrated that ¹H-MRS accurately differentiated normal from tumoral brain tissue and confirmed the superiority of the semi-automatic quantification method.

Para analizar la calidad microbiológica en vegetales tipo hoja y la incidencia de bacterias enteropatógenas se analizaron 150 muestras (50 lechugas, 50 cilantros y 50 perejiles) recolectadas en dos supermercados de Maracaibo. Se determinó Coliformes Totales (CT) y Escherichia coli (EC) según la norma COVENIN Nº3276:1997; para la determinación de bacterias enteropatógenas (Salmonella, Aeromonas y Vibrio) se utilizaron medios de enriquecimiento y selectivos. La identificación de especies se realizó empleando pruebas bioquímicas. En 81,33% (122/150) de las muestras se obtuvieron contajes de CT entre 10³-10(5) UFC/g. La recuperación de EC fue de 10,00%. La frecuencia de enteropatógenos fue de 28%, siendo Aeromonas el género más aislado con un 95,91%. La mayor recuperación de enteropatógenos se obtuvo en las muestras de cilantro (40,00%), seguida de perejil (34,00%) y lechuga (20,00%); A. caviae fue la especie más recuperada (59,18%) seguida de A. hydrophila (30,62%). Salmonella spp se recuperó en 2 (4,08%) muestras. La presencia de indicadores entéricos (CT y EC) y de bacterias enteropatógenas sugiere que los vegetales tipo hoja presentan una inadecuada calidad sanitaria y pueden ser fuente de gastroenteritis.

To analyze the microbiological quality of leaf vegetables and the incidence of enteropathogenic bacteria, 150 samples (50 lettuce, 50 coriander and 50 parsley) collected in two supermarkets in Maracaibo, were studied. Total coliforms (TC) and Escherichia coli (EC) according to COVENIN guideline N° 3276: 1997, were determined; for the identification of enteropathogenic bacteria (Salmonella, Aeromonas, Vibrio), enrichment and selective media were used. Species identification was made using biochemical tests. In 81.33% (122/150) of the samples obtained, TC counts were between 10³-10(5) CFU/g. EC recovery was 10.00%. The frequency of enteropathogens was 28%, with Aeromonas the most isolated genus (95.91%). Greater recovery of enteropathogens was obtained from coriander (40.00%), followed by the parsley (34.00%) and lettuce samples (20.00%); A. caviae was the most recovered specie (59.18%) followed by A. hydrophila (30,62%). Salmonella spp were recovered in 2 samples (4.08%). The presence of enteric indicators (TC and EC) and enteropathogenic bacteria suggests that the sanitary condition of the leafy vegetables is inadequate and can be a source of gastroenteritis.

Computed tomography (CT) images are routinely used to assess ischemic brain stroke in the acute phase. They can provide important clues about whether to treat the patient by thrombolysis with tissue plasminogen activator. However, in the acute phase, the lesions may be difficult to detect in the images using standard visual analysis. The objective of the present study was to determine if texture analysis techniques applied to CT images of stroke patients could differentiate between normal tissue and affected areas that usually go unperceived under visual analysis. We performed a pilot study in which texture analysis, based on the gray level co-occurrence matrix, was applied to the CT brain images of 5 patients and of 5 control subjects and the results were compared by discriminant analysis. Thirteen regions of interest, regarding areas that may be potentially affected by ischemic stroke, were selected for calculation of texture parameters. All regions of interest for all subjects were classified as lesional or non-lesional tissue by an expert neuroradiologist. Visual assessment of the discriminant analysis graphs showed differences in the values of texture parameters between patients and controls, and also between texture parameters for lesional and non-lesional tissue of the patients. This suggests that texture analysis can indeed be a useful tool to help neurologists in the early assessment of ischemic stroke and quantification of the extent of the affected areas.

This report outlines the utility of a 3D -> 1D transformation of peptide conformation, which leads to a linearized notation of protein secondary and tertiary structures that may be used for an objective description of protein folding. The method is intended to be descriptive and not to be predictive. It is established from first principles that the idealized 2D-y-f map must have nine minima. It is obvious to ask whether all these nine conformations are actually occurring in proteins. The objective is to repeat a previous analysis of 258 proteins determined using program ECEPP2, with the improved ECEPP2 + polarization. An analysis is performed on 258 proteins with known X-ray structure. The proteins contain 56 495 amino-acid residues with well-defined f and y angles. The minima are identified with the aid of the nine ECEPP2 minima of Ac-Ala-NHMe with f and y ± 40° tolerance. ECEPP2 is improved with the inclusion of the interacting induced-dipole polarization model, SIMPLEX-MS 3 geometry optimization and the calculation of the dipole moment from the point distribution of net charges. The analysis of 258 proteins determined using ECEPP2 is repeated with the improved ECEPP2 + polarization. The relative frequency of occurrence of those conformations energetically favoured for enantioners g-g-, etc. in the y-f map of the backbone conformations of amino acids decreases as: g-a/g+a > g-g+/g+g- > g-g-/g+g+ >> ag+/ag- > aa. For the amino acids, the same preference diminishes as: Pro >> Ile > Val > Leu > Thr > Met > Ala > Glu > Phe > Trp > Tyr > Gln > Lys > Ser > Cys > Arg > Asp > His > Asn > Gly. The strong preference of Pro is in agreement with its character of a-helix and b sheet breaker, and b turn and random-coil former. The analysis of 258 proteins determined using ECEPP2 is repeated with the improved ECEPP2 + polarization and there is a good agreement between the two. Achiral Gly relative frequencies of occurrence are close to one. Pro is the amino acid with the greatest (g-g-, etc.)/(g+g+, etc.) preference and with the greatest influence on protein conformation. Pro is the amino acid with the largest Pglobal conformational parameter. The original software used in the investigation is available from the author.

Este reporte reseña la utilidad de una transformación de conformación de péptido 3D ->1D, que conduce a una notación linealizada de estructuras de proteínas secundarias y terciarias la cual puede ser usada para una descripción objetiva del plegamiento de proteínas. El método tiene la intención de ser descriptivo y no predictivo. Desde los primeros principios se ha establecido que el mapa 2D-y-f idealizado debe tener nueve mínimos. Es obvia la pregunta, entonces, si todas las nueve conformaciones ocurren realmente en proteínas. El objetivo es repetir un análisis previo, realizado con el programa ECEPP2 en 258 proteínas, con estructura de Rayos-X conocida, utilizando el mejorado ECEPP2 + polarización. Estas proteínas contienen 56496 residuos amino ácidos con ángulos f y y bien definidos. Los mínimos son identificados con la ayuda de los nueve mínimos obtenidos para Ac-Ala-NHMe por ECEPP2 con tolerancia ± 40° para f y y. ECEPP2 es mejorado con la inclusión del modelo de polarización de dipolo inducido SIMPLEX-MS 3en la optimización de geometrías y el cálculo del momento dipolar a partir de la distribución puntual de cargas netas. La frecuencia relativa de ocurrencia de aquellas conformaciones energéticamente favorecidas por los enantiómeros g-g-, etc. en el mapa y-f de las conformaciones del esqueleto de amino ácidos decrece como: g-a/g+a > g-g+/g+g- > g-g-/g+g+ >> ag+/ag- > aa. Para los amino ácidos, la misma preferencia disminuye en el sentido: Pro >> Ile > Val > Leu > Thr > Met > Ala > Glu > Phe > Trp > Tyr > Gln > Lys > Ser > Cys > Arg > Asp > His > Asn > Gly. La fuerte preferencia de Pro está de acuerdo con su carácter rompedor de a-hélices y b-hojas, y formador de b-giros y ovillos aleatorios. El análisis de 258 proteínas determinadas utilizando ECPP2 se repitió utilizando el mejorado ECEPP2 + polarización y hay buen acuerdo entre los dos métodos. Las frecuencias relativas de ocurrencia de Gly aquiral son próximas a uno. Pro es el amino ácido con la mayor preferencia (g-g-, etc.)/(g+g+, etc.) y con mayor influencia en la conformación de proteínas. Pro es el amino ácido con el mayor parámetro conformacional Pglobal. El software original utilizado en la investigación está disponible por parte del autor.

A case of gangliocytic paraganglioma of the papilla of Vater in a 76-year-old man with a history of recurrent obstructive jaundice is presented. This is the first case of gangliocytic paraganglioma of the major papilla succesfully resected by endoscopic ampullectomy.

Se describe un caso de paraganglioma gangliocítico de la papila de Vater, en un varón de 76 años, manifestado con cuadros de ictericia obstructiva recidivante. Este es el primer caso descrito de paraganglioma de la papila mayor resuelto eficazmente mediante ampulectomía endoscópica.