Modulation of motor inhibition by subthalamic stimulation in obsessive-compulsive disorder.

High-frequency deep brain stimulation of the subthalamic nucleus can be used to treat severe obsessive-compulsive disorders that are refractory to conventional treatments. The mechanisms of action of this approach possibly rely on the modulation of associative-limbic subcortical-cortical loops, but remain to be fully elucidated. Here in 12 patients, we report the effects of high-frequency stimulation of the subthalamic nucleus on behavior, and on electroencephalographic responses and inferred effective connectivity during motor inhibition processes involved in the stop signal task. First, we found that patients were faster to respond and had slower motor inhibition processes when stimulated. Second, the subthalamic stimulation modulated the amplitude and delayed inhibition-related electroencephalographic responses. The power of reconstructed cortical current densities decreased in the stimulation condition in a parietal-frontal network including cortical regions of the inhibition network such as the superior parts of the inferior frontal gyri and the dorsolateral prefrontal cortex. Finally, dynamic causal modeling revealed that the subthalamic stimulation was more likely to modulate efferent connections from the basal ganglia, modeled as a hidden source, to the cortex. The connection from the basal ganglia to the right inferior frontal gyrus was significantly decreased by subthalamic stimulation. Beyond motor inhibition, our study thus strongly suggests that the mechanisms of action of high-frequency subthalamic stimulation are not restricted to the subthalamic nucleus, but also involve the modulation of distributed subcortical-cortical networks.

[Clinical aspects in polyps of the colon]. / Aspectos clínicos de los pólipos colónicos.

INTRODUCTION: The colonics polyps according to their number, size, location, age of presentation and mainly, according to their histology, have the potentiality of malignant degeneration, which makes of a continuous study and pursuit susceptible. OBJECTIVES: To evaluate the relation between the histologic type of the colon polyps, its location, the degree of dysplasia, the size, its possible commitment by carcinoma, the age, sex and the handling that has occurred them, in a series of 684 patients of the National Institute of Enfermedades Neoplásicas (INEN) between the 1 of January from 1974 to the 31 of March of the 2004. MATERIAL AND METHODS: The revision of clinical histories of 840 patients with the diagnosis of colon polyp was made who attended the service of Gastroenterology of the INEN between the 1 of January from 1974 to the 31 of March of 2004 and a card predesigned for each clinical history filled. The study is of observational, analytical type and of cross section. 1162 resecteds polyps evaluated themselves in this period. 156 patients by diagnosis related to cancer and familiar adenomatouspoliposis did not include themselves. The final sample was of 684 patients, in whom it was 1057 polyps. Other endoscopic findings were: internal hemorrhoids (172), colonic diverticulosis (50), anal fissure (4), and nonspecific ulcerative colitis (2). The statistical processing was made with program SPSS 12. For the qualitative variables the method of the Chi-square was used, for the quantitative variables analyzed the average, the rank and the variance. RESULTS: 1057 polyps extirpated, by means of the endoscopy polipectomy were 1016, with colectomy were 32 and with transanal resection without colectomy they 9. Within the histology of the 1057 polyps, 331 was briefed (31.3%) that were hyperplasic, 448 (42.4%) adenomas, 278 (26.3%) others and 35 (8.2%) adenocarcinomas on adenomas. The average age was of 50 years, was no significant difference with sex. The location but frequence of the adenomas was in the left colon (76.6%). Adenocarcinoma (carcinomas on adenomas), was present mainly in polyps villous type, with dysplasia severe and greater to 10 mm. Nevertheless, in smaller polyps of 5mm with dysplasia severe, was a polyp invaded by cancer, that represents the 0,8% of millimetric polyps. The made handling was mainly endoscopic, with 96% of the resected polyps this way, also slogan transanal resection and segmental colonic resection. The colectomy was necessary in 3% of all the made interventions, dysplasia severe or carcinoma was made in adenomatous polyps with, and in greater percentage in greater polyps of 20 mm (53%). The single polipectomy was sufficient in the level of invasion Haggitt 0. In patients with level of invasion Haggitt 1 and 2, the single polipectomy was the election treatment. On the other hand, in polyps with level of invasion Haggitt 3 and 4, the colectomy was the election treatment. One briefed two complications, one of perforation and peritonitis and another one of digestive hemorrhage loss (both: 0.29%), without mortality events. CONCLUSIONS: The Evaluation of colonic polyps in INEN is predominantly by endoscopy. The polyps are more frequent over the 50 years and have preferred location in the left colon. The carcinoma is more probable with severe dysplasia and greater size of the adenoma. All polyps, from the millimetric ones, including the hyperplasic, must be considered marks of neoplasia and extirpated in its totality.

Aspectos clínicos de los pólipos colónicos / Clinical aspects of the colonics polyps

Introducción: Los pólipos colónicos de acuerdo a su número, tamaño, localización, edad de presentación y sobre todo, de acuerdo a su estirpe histológica, tienen la potencialidad de degeneración maligna, lo que los hace susceptibles de un continuo estudio y seguimiento. Objetivos: Evaluar la relación entre el tipo histológico de los pólipos de colón, su localización, el grado de displasia, el tamaño, su eventual compromiso por carcinoma, la edad, el sexo y el manejo que se les ha dado, en una serie de 684 pacientes del Instituto Nacional de Enfermedades Neoplásicas (INEN) entre el 1 de enero de 1974 al 31 de marzo del 2004. Material y métodos: Se realizó la revisión de historias clínicas de 840 pacientes con el diagnóstico de pólipo de colon que asistieron al Servicio de Gastroenterología del INEN entre el 1 de enero de 1974 al 31 de marzo de 2004 y se llenó una ficha prediseñada para cada historia clínica. El estudio es de tipo observacional, analítico y de corte transversal. Se evaluaron en este periodo 1162 pólipos resecados. No se incluyeron 156 pacientes por diagnóstico relacionado con cáncer y poliposis adenomatosa familiar. La muestra final fue de 684 pacientes, en los que se encontró 1057 pólipos. Otros hallazgos endoscópicos fueron: hemorroides internas (172), diverticulosis colónica (50), fisura anal (4), y colitis ulcerativa no específica (2). El procesamiento estadístico se realizó con el programa SPSS 12. Para las variables cualitativas se empleó el método de Chi-cuadrado, para las variables cuantitativas se analizaron la media, el rango y la varianza. Resultados: Se extirparon 1057 pólipos, mediante la polipectomía endoscópica fueron 1016, con uso de colectomía fueron 32 y con resección transanal sin colectomía fueron 09. Dentro de la histología de los 1057 pólipos, se consignaron 331 (31.3 por ciento) que fueron hiperplásicos, 448 (42.4 por ciento) adenomas, 278 (26.3 por ciento) otros y 35 (8.2 por ciento) adenocarcinomas sobre adenomas...

Introduction: The colonics polyps according to their number, size, location, age of presentation and mainly, according to their histology, have the potentiality of malignant degeneration, which makes of a continuous study and pursuit susceptible. OBJECTIVES: To evaluate the relation between the histologic type of the colon polyps, itslocation, the degree of dysplasia, the size, its possible commitment by carcinoma, the age, sex and the handling that has occurred them, in a series of 684 patients of the National Institute of Enfermedades Neoplásicas (INEN) between the 1 of January from 1974 to the 31 of March of the 2004. MATERIAL AND METHODS: The revision of clinical histories of 840 patients with the diagnosis of colon polyp was made who attended the service of Gastroenterology of the INEN betweenthe 1 of January from 1974 to the 31 of March of 2004 and a card predesigned for each clinical history filled. The study is of observational, analytical type and of cross section. 1162 resecteds polyps evaluated themselves in this period. 156 patients by diagnosis related to cancer and familiar adenomatouspoliposis did not include themselves. The final samplewas of 684 patients, in whom it was 1057 polyps. Other endoscopic findings were: internal hemorrhoids (172), colonic diverticulosis (50), anal fissure (4), and nonspecific ulcerative colitis (2). The statistical processing was made with program SPSS 12. For the qualitative variables the method of the Chi-square was used, for the quantitative variables analyzed theaverage, the rank and the variance. RESULTS: 1057 polyps extirpated, by means of the endoscopy polipectomy were 1016, with colectomy were 32 and with transanal resection without colectomy they 9. Within the histologyof the 1057 polyps, 331 was briefed (31.3 per cent) that were hyperplasic, 448 (42.4 per cent) adenomas,278 (26.3 per cent) others and 35 (8.2 per cent) adenocarcinomas on adenomas. The average age was of50 years, ...

Scale separation in granular packings: stress plateaus and fluctuations.

It is demonstrated, by numerical simulations of a 2D assembly of polydisperse disks, that there exists a range (plateau) of coarse-graining scales for which the stress tensor field in a granular solid is nearly resolution independent, thereby enabling an "objective" definition of this field. Expectedly, it is not the mere size of the system but the (related) magnitudes of the gradients that determine the widths of the plateaus. Ensemble averaging (even over "small" ensembles) extends the widths of the plateaus to subparticle scales. The fluctuations within the ensemble are studied as well. Both the response to homogeneous forcing and to an external compressive localized load (and gravity) are studied. Implications to small solid systems and constitutive relations are briefly discussed.

[Primary gastric lymphoma]. / Linfoma gastrico primario.

INTRODUCTION: Primary Gastric Lymphoma is an uncommon malignancy among gastric malignancies. Histology of the Primary Gastric Lymphoma is varied and the extranodal marginal zone B-cells lymphoma is specially significant on account of its potential remission with antibiotic therapy. OBJECTIVES: Observe the clinical characteristics of patients with Primary Gastric Lymphoma, assess the most relevant endoscopic findings, identify the factors that influence survival and evaluate the effects of therapy. MATERIALS AND METHODS: The study is an observational, analytical, cross evaluation including 169 patients with histological diagnosis of Gastric Lymphoma, treated at the National Institute for Neoplastic Diseases, Lima, Peru, from January 1995 to December 2000. Staging was based on the Ann Arbor system, modified by Musshoff and histology, on the REAL-WHO classification. The statistical analysis included the student-t and the chi-square tests. Survival data were entered using the Kaplan Meier curves and prognosis factors, using the Cox regression test. RESULTS: The sample represents patients from the Peruvian Coast, with a mean age of 55 years old and slight predominance of female patients (54.4%). Signs and symptoms are unspecific. Clinical stage I-II corresponds to 75% of the patients. The endoscopic pattern of multiple ulcerated lesions is characteristic of the Gastric Lymphoma. A total of 71% of the patients with extranodal marginal zone B-cells lymphoma showed total remission of the disease with antibiotic therapy (5/7). The histological type of the Gastric Lymphoma in the 169 patients was as follows: Large, diffuse, B-cells Lymphoma, 137 patients, extranodal marginal zone B-cells lymphoma, 16 patients, peripheral T-cell Lymphoma, 6 patients, anaplastic large T-cell Lymphoma, 3 patients, undetermined Lymphoma, 3 patients, mantle cell Lymphoma, 2 patients, adult T-cell Lymphoma, 1 patient and follicular Lymphoma, 1 patient. Global survival after 36 months was of 61.34%, survival according to the histological type was of 92.31% for extranodal marginal zone B-cells Lymphomas, 62.21% for large, diffuse B-cells Lymphomas and 29.63% for T-cell Lymphomas. Survival after 36 months in patients in clinical stage I-II treated with chemotherapy, was of 82.16%, with surgery, 71.89% and with surgery and chemotherapy, 70.39, with similar results in all three groups (p: 0.6530). The groups classified according to the international index, showed a clear difference between them (p:0.0000). The univariate analysis revealed that Zubrod (p:0.0000) DHL (p:0.0073) disease remission (p:0.0000) stage (p:0.0000) treatment (p:0.0000) and location (p:0.0000) had statistical significance. Multivariate analysis showed that in the Cox regression model, remission (OR:13,342, p:0.0000) and location (OR:2.375, p:0.041) fall within the equation of such function. CONCLUSIONS: The multiple ulcerated lesions are characteristic of the Gastric Lymphoma. Remission of the disease in the extranodal marginal zone B-cells Lymphoma is evidenced with the use of antibiotic therapy (5/7). Chemotherapy in patients with EC I-II achieves survival results similar to those treated with surgery and with a combination of both. Validity of the international index is confirmed and the multivariate analysis proved that remission and location of the disease have statistical significance.

Strain versus stress in a model granular material: A Devil's staircase

The series of equilibrium states reached by disordered packings of rigid, frictionless disks in two dimensions, under gradually varying stress, are studied by numerical simulations. Statistical properties of trajectories in configuration space are found to be independent of specific assumptions ruling granular dynamics, and determined by geometry only. A monotonic increase in some macroscopic loading parameter causes a discrete sequence of rearrangements. For a biaxial compression, we show that, due to the statistical importance of such events of large magnitude, the dependence of the resulting strain on stress direction is a Levy flight in the thermodynamic limit.

Enfermedad quística congénita del sistema biliar / Congenital cystic disease of the biliary system

Se efectúa el estudio de 12 pacientes con diagnóstico de enfermedad quística congénita del sistema biliar, en diez de estos la comprobación fue quirúrgica. Según la clasificación de Todani, 8 (67%) correspondieron al tipo I, 2(17%) al tipo IVA y al tipo V los dos restantes (17%). Nueve pacientes (75%) fueron del sexo femenino. Seis de los pacientes (50%), estuvieron comprendidos entre los 30 y 39 años de edad. Las manifestaciones clínicas más frecuentes fueron: Dolor abdominal (83%), náusea (75%), coluria (66%), ictericia (58%), hepatomegalia (50%), y fiebre (50%). En 8 pacientes (67%), se registró elevación de la fosfatasa alcalina y en 7 (58%), de las aminotransferasas. El procedimiento diagnóstico de mayor efectividad fue la ecografia (86%). Diez pacientes fueron sometidos a cirugia, ellos correspondieron a la totalidad de los pacientes con quistes tipo I y IVA. En tres pacientes se comprobó litiasis intraquística y en uno se documentó cirrosis hepática