Light and electron microscopic immunocytochemical localization of vasoactive intestinal polypeptide VIP-like activity in the rat small intestine

Vasoactive intestinal polypeptide nerve processes and cell bodies were identified by electron microscopic immunocytochemistry in the rat small intestine. Labeled nerve processes were numerous in the inner circular smooth muscle coat and mainly in the mucosa, but were absent in the longitudinal muscle layer. Submucosal blood vessels were often surrounded by immunoreactive vasoactive intestinal polypeptide positive nerves, in close associations (distance less than 40 mn) to blood vessel basement membranes and to smooth muscle cells. In the ganglia of the myenteric and submucous plexuses, labeled fibers surrounded unstained neural cell bodies. The synaptic vesicles of vasoactive intestinal polypeptide positive terminals were 35-40 nm in diameter and some dense core vesicles (80-120 nm in diameter) were also observed in the same profiles. These observations suggest that vasoactive intestinal polypeptide nerves may participate in regulating smooth muscle activity and local blood flow in the small intestine.     

Cardiac receptors with non-medullated vagal afferents in the rat.

The characteristics of 22 atrial receptors in 15 normotensive adult male Wistar rats were investigated. All the receptor afferents were included in the C-fibre group with conduction velocities from 0.4 to 1.2 m/sec. No atrial medullated receptors or ventricular C-fibre endings were found. Two receptors were located in right atrium and 2 receptors throughout left atrium. Upon elevation of the left atrial pressure the receptor discharge was markedly elevated with thresholds from 2.5 to 9 mmHg in mean left atrial pressure. Ten of the atrial receptors displayed a clear cardiac rhythmicity upon activation and the discharge correlated with the v-wave, indicating distension as the cause of receptor activation. The maximal firing rate in most receptors was very high (up to 70 Hz), but 8 receptors had maximal firing rates below 25 Hz. These low frequency receptors had higher threshold and showed a more irregular firing. Thus, there is a substantial population of atrial receptors with vagal non-medullated afferents in the rat heart and the thresholds for many of these receptors are so low that they are likely to be active during normal conditions.     

Effects of single and continuous administration of amyloid beta-peptide (25-35) on adenylyl cyclase activity and the somatostatinergic system in the rat frontal and parietal cortex

It is unknown whether the amyloid beta-peptide (Abeta), a principal component found in extracellular neuritic plaques in the brain of patients with Alzheimer's disease (AD), is capable of altering adenylyl cyclase (AC) activity and the somatostatin (SRIF) receptor-effector system in the cerebral cortex of the patients. Therefore, the objective of this study was to investigate the effect of the beta fragment, beta (25-35), on AC activity and the somatostatinergic system in the rat frontoparietal cortex. A single dose of beta (25-35) (10microg) injected intracerebroventricularly significantly decreased the density of SRIF receptors (27.4%) and increased their affinity (32.2%) in the frontoparietal cortex. The inhibitory effect of SRIF on basal and forskolin (FK)-stimulated AC activity was significantly lower in the beta (25-35)-treated rats when compared with controls. beta (25-35) did not modify Gialpha1, Gialpha2 nor Gialpha3 levels in membranes from the frontoparietal cortex. Continuous infusion of the peptide induced a decrease in the SRIF receptor density in this brain area to a similar extent as that observed 14 days after the single administration of the peptide. Likewise, this treatment decreased the SRIF receptor density in the frontal cortex (15.3%) and parietal cortex (27.2%). This effect was accompanied by a decrease in the SRIF-mediated inhibition of FK-stimulated AC activity (from 41.6% to 25.6%) in the frontal cortex as well by a decrease in basal AC activity (from 36.9% to 31.6%) and FK-stimulated AC activity (from 35.6% to 27.1%) in the parietal cortex. Continuous infusion of Abeta (25-35) had no effect on Gialpha1, Gialpha2 or Gialpha3 levels in membranes from frontal and parietal cortex. However, this treatment caused a decrease in SRIF-like immunoreactivity content in the parietal (38.9%) and frontal (20.4%) cortex. These results suggest that Abeta might be involved in the alterations of somatostatinergic system reported in AD.     

Isolations of Corynebacterium kroppenstedtii from a breast abscess

The recently described species Corynebacterium kroppenstedtii was isolated from a breast abscess in a 38-year-old woman on two occasions. We discuss the pathogenic role of this bacteria and the methods used for its isolation.     

Using Bayesian networks in the construction of a bi-level multi-classifier. A case study using intensive care unit patients data

Combining the predictions of a set of classifiers has shown to be an effective way to create composite classifiers that are more accurate than any of the component classifiers. There are many methods for combining the predictions given by component classifiers. We introduce a new method that combine a number of component classifiers using a Bayesian network as a classifier system given the component classifiers predictions. Component classifiers are standard machine learning classification algorithms, and the Bayesian network structure is learned using a genetic algorithm that searches for the structure that maximises the classification accuracy given the predictions of the component classifiers. Experimental results have been obtained on a datafile of cases containing information about ICU patients at Canary Islands University Hospital. The accuracy obtained using the presented new approach statistically improve those obtained using standard machine learning methods.     

Coordinate-based versus structural approaches to brain image analysis

A basic issue in neurosciences is to look for possible relationships between brain architecture and cognitive models. The lack of architectural information in magnetic resonance images, however, has led the neuroimaging community to develop brain mapping strategies based on various coordinate systems without accurate architectural content. Therefore, the relationships between architectural and functional brain organizations are difficult to study when analyzing neuroimaging experiments. This paper advocates that the design of new brain image analysis methods inspired by the structural strategies often used in computer vision may provide better ways to address these relationships. The key point underlying this new framework is the conversion of the raw images into structural representations before analysis. These representations are made up of data-driven elementary features like activated clusters, cortical folds or fiber bundles. Two classes of methods are introduced. Inference of structural models via matching across a set of individuals is described first. This inference problem is illustrated by the group analysis of functional statistical parametric maps (SPMs). Then, the matching of new individual data with a priori known structural models is described, using the recognition of the cortical sulci as a prototypical example.     

Complete sparing of high-contrast color input to motion perception in cortical color blindness

It is widely held that color and motion are processed by separate parallel pathways in the visual system, but this view is difficult to reconcile with the fact that motion can be detected in equiluminant stimuli that are defined by color alone. To examine the relationship between color and motion, we tested three patients who had lost their color vision following cortical damage (central achromatopsia). Despite their profound loss in the subjective experience of color and their inability to detect the motion of faint colors, all three subjects showed surprisingly strong responses to high-contrast, moving color stimuli--equal in all respects to the performance of subjects with normal color vision. The pathway from opponent-color detectors in the retina to the motion analysis areas must therefore be independent of the damaged color centers in the occipitotemporal area. It is probably also independent of the motion analysis area MT/V5, because the contribution of color to motion detection in these patients is much stronger than the color response of monkey area MT.