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In this article, the activity of lower gamma band was used to classify right and left elbow movements performed from real and imaginary tasks in two different cognitive states: the preparation and the movement execution. Discriminability maps were used both to generalize the signal behavior of all the volunteers and to select time intervals of high discrimination among classes. The features extracted from chosen intervals were tested in eight different classification algorithms. To improve classes discrimination, LDA was used for dimensional reduction. Algorithms were tested using a fivefold cross-validation. The results showed similar signal activity for both real and imaginary actions, obtaining closer classification responses among all volunteers. The tested algorithm gave a mean classification success up to 70%, with minor differences between the type of task and the cognitive state.

The representation of the two eyes in striate cortex (V1) ofCebus monkeys was studied by electrophysiological single-unit recordings in normal animals and by morphometric analysis of the pattern of ocular dominance (OD) stripes, as revealed by cytochrome oxidase histochemistry in V1 flat-mounts of enucleated animals. Single-unit recordings revealed that the large majority of V1 neurons respond to the stimulation of either eye but are more strongly activated by one of them. As in other species of monkey, neurons with preference for the stimulation of the same eye are grouped in columns 300–400 µm wide, spanning all cortical layers. Monocular neurons are clustered in layer IVc, specially in its deeper half (IVc-beta), and constitute less than 10% of the population of other layers. Neurons with equal responses to each eye are more commonly found in layer V than elsewhere in V1. In the supragranular layers and in granular layer IVc-alpha neurons strongly dominated by one of the eyes tend to be broadly tuned for orientation, while binocularly balanced neurons tend to be sharply tuned for this parameter. No such correlation was detected in the infragranular layers, and most neurons in layer IVc-beta responded regardless of stimulus orientation. Ocular dominance stripes are present throughout most of V1 as long, parallel or bifurcating bands alternately dominated by the ipsi- or the contralateral eye. They are absent from the cortical representations of the blind spot and the monocular crescent. The domains of each eye occupy nearly equal portions of the surface of binocular V1, except for the representation of the periphery, where the contralateral eye has a larger domain, and a narrow strip along the border of V1 with V2, where either eye may predominate. The orderliness of the pattern of stripes and the relationship between stripe arrangement and the representation of the visual meridians vary with eccentricity and polar angle but follow the same rules in different animals. These results demonstrate that the laminar, columnar and topographic distribution of neurons with different degrees of OD in V1 is qualitatively similar in New- and Old World monkeys of similar sizes and suggest that common ancestry, rather than parallel evolution, may account for the OD phenotypes of contemporaneous simians.

The behaviour of an on-line post-column reactor system based on the use of Ce(IV) reagent in acidic medium for the liquid chromatographic amperometric determination of non-volatile nitrosamines has been investigated in a two-line flow manifold coupled with a flow-through voltammetric detector equipped with twin gold electrodes for both mono- and biamperometric detection modes. The physical dispersion coefficients and the time domain parameters of the current peak responses obtained by flow injections of both Ce(III) and nitrite in aqueous and mixed water-acetonitrile carriers were used to evaluate the performance of the flow reactor elements. Mono- and biamperometric measurements allowed the determination of the linear dynamic ranges, the sensitivities and the detection limits of nitrite under different experimental conditions with respect to the composition of the carrier liquid and the temperature of the reactor system. Peak standard deviations were calculated and used to predict the effects of band broadening and tailing induced by the reactor system on the chromatographic bands.

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Rabbit red blood cell hexokinase (EC 2.7.1.1) has been shown to be inactivated in vitroby incubating intact erythrocytes in the presence of an oxygen-radical-generating system represented by ascorbate and iron. It was interesting to note that among the glycolytic enzymes, only hexokinase was found to be susceptible to the action of oxygen radicals, suggesting that the loss of activity of this enzyme may be one of the first signals of cellular damage in rabbit red blood cells. This statement is supported by the fact that, under the experimental conditions used, we did not observe any significant plasma membrane lipid peroxidation nor intracellular proteolysis. Furthermore, mature erythrocytes are unable to synthesize hexokinase as well as other proteins de novo;therefore, the inactivation of this enzyme, which is both the first and one of the rate-limiting enzymes of the glycolytic pathway, could play an important role in determining metabolic impairment of red blood cells, with possible physiological implications. We also investigated the effect of various radical scavengers and antioxidants (glucose, vitamin E, dithiothreitol, flavonoids) which are able to influence the inactivation of hexokinase activity to different extents. Finally, under the experimental conditions used (90 min of incubation at 37°C), we did not observe any difference in the hemolysis of rabbit red blood cells incubated in the presence or absence of ascorbate and iron (hemolysis was about 1% after 90 min of incubation), suggesting that the system used was able to furnish information about the cellular damage produced by oxygen radicals without provoking cell lysis.

Summary Treatment of cultured mammalian cells with hydrogen peroxide results in the production of extensive DNA damage. Strand breakage was produced at the level of either nascent or mature DNA and the former target appeared slightly more resistant than the latter. Although inhibitors of the enzyme poly(ADP-ribose) polymerase similarly retarded the repair of such lesions, removal of DNA strand breaks was much slower for the newly synthesized DNA as compared to mature DNA.

The presence of ocular dominance (OD) stripes in layer IVc of striate cortex (V1) is characteristic of all Old World simians so far studied. In contrast, some species of New World monkeys do not have ocular dominance stripes, and in those that do, the pattern of stripes may be different from that shown in Old World monkeys. This difference has led to the suggestion that OD stripes evolved independently in both groups. We have mapped the entire system of OD stripes in the New World monkey Cebus, by means of cytochrome oxidase histochemistry after monocular enucleation. A striking similarity was found between the patterns in Cebus and Macaca, which is suggestive of common ancestry, rather than parallel evolution.

In this paper we describe the use of high performance liquid chromatography (HPLC) and capillary electrophoresis (CE) as rapid and automated techniques for the analysis of DNA fragments generated by the polymerase chain reaction. Unlike traditional slab gel electrophoresis, these techniques allow a single-step qualitative and quantitative analysis of DNA. Furthermore, both techniques allow the detection of DNA fragments with high sensitivity in the subnanogram to microgram range. The complete automation of the instrumentation permit the unattended analysis of a great number of samples, and the direct entry of the data into a computer facilitates the processing of large numbers of PCR products. Furthermore, the HPLC technique allows the recovery with quantitative yield of pure DNA fragments suitable for other applications.