bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acetaminophen potentiates staurosporine‐induced death in a human neuroblastoma cell line
Authors: Posadas I , Vellecco V , Santos P , Prieto‐Lloret J , Ceña V 
Published: January 2007

Background and purpose:Neuroblastoma is the most common solid tumour in infants characterized by a high resistance to apoptosis. Recently, the cyclo‐oxygenase pathway has been considered a potential target in the treatment of different kinds of tumours. The aim of the present work was to investigate a possible relationship between cyclo‐oxygenase pathway and stauroporine‐induced apoptosis in the neuroblastoma cell line SH‐SY5Y.Experimental approach:Cellular viability was measured by release of LDH. DNA fragmentation was visualized by electrophoresis on agarose gel containing ethidium bromide. Cyclo‐oxygenase activity was measured in microsomal fractions obtained from cells by quantification of its final product PGE2by RIA. Caspase‐3 activity was measured fluorimetrically and Western blot analysis was performed to assess cytochrome c expression.Key results:We have found that staurosporine (500 nM) induced cellular death in a time‐dependent manner in SH‐SY5Y human neuroblastoma cells. Cyclo‐oxygenase enzymatic activity was present in SH‐SY5Y human neuroblastoma cells under basal conditions and pharmacological experiments using COX inhibitors indicate that cyclo‐oxygenase‐1 and cyclo‐oxygenase‐3 are the active isoforms in these cells. Co‐incubation of SH‐SY5Y cells with staurosporine (500 nM) and acetaminophen for 24 h potentiated staurosporine‐mediated cellular death in a concentration‐dependent manner. This process is mediated by an increase in cytochrome c release and caspase 3 activation and is prevented by N‐acetylcysteine or the superoxide dismutase mimetic, MnTBAP.Conclusions and implications:Acetaminophen potentiates staurosporine‐mediated neuroblastoma cell death. The mechanism of action of acetaminophen seems to be related to production of reactive oxygen species and decreased intracellular glutathione levels.British Journal of Pharmacology(2007)150, 577–585. doi:10.1038/sj.bjp.0706993
Effects of chronic nitric oxide synthase inhibition on the cardiovascular responses to cannabinoids in vivo and in vitro
Authors: Wheal A J , Bennett T , Randall M D , Gardiner S M 
Published: January 2007

Background and purpose:Since the vasorelaxant potency of the endocannabinoid anandamide is enhanced in perfused mesenteric vascular beds from rats made hypertensive by chronic inhibition of NO synthase (L‐NAME in drinking water), we hypothesized that in vivo, anandamide‐induced vasodilatation would be similarly enhanced in L‐NAME‐treated animals.Experimental approach:Male Sprague‐Dawley rats were given L‐NAME in drinking water (7.5 mg kg−1 day−1) for 4 weeks. Relaxant effects of anandamide were measured in perfused mesenteric vascular beds and in isolated small mesenteric arteries. Renal, mesenteric and hindquarters haemodynamic responses to anandamide, methanandamide, the synthetic cannabinoid agonist WIN‐55212‐2 and the cannabinoid receptor antagonist AM251 were assessed in conscious, chronically‐instrumented rats.Key results:Vasorelaxant responses to anandamide were enhanced in the perfused mesentery but not in isolated mesenteric resistance vessels. In vivo, anandamide caused vasodilatation only in the hindquarters vascular bed and only in control rats. Methanandamide caused a late‐onset (40 min after administration) tachycardia, mesenteric and hindquarters vasoconstriction, and renal vasodilatation, which did not differ between control and L‐NAME‐treated rats. AM251 had no effect on resting blood pressure in control or L‐NAME‐treated rats and WIN55212‐2 caused pressor and renal and mesenteric vasoconstrictor responses, with hindquarters vasodilatation in both groups of animals.Conclusions and Implications:The results provide no in vivo evidence for enhanced vasodilator responses to cannabinoids, or up‐regulation of endocannabinoids or their receptor activity, following chronic NO synthase inhibition.British Journal of Pharmacology (2007) 150, 662–671. doi:10.1038/sj.bjp.0707136
Réponses évoquées par les mouvements oculaires d'exploration (réponse lambda): Rôle des afférences intervenant à divers moments du processus oculo-moteur
Authors: Lesèvre Nicole , Rémond A 
Published: January 2007

Experiments are reported the aim of which was to elucidate the cause of each of the components of the lambda response, and particularly to evaluate the role of ‘on’ and ‘off’ visual effects which appear at various times during the oculomotor process and also the possible influence of non-visual mechanisms. Eight subjects with normal sight were studied under the following conditions: (i) horizontal eye movements of 12° were guided by fixation points placed on a dimly-lit uniform black field of 20°; a checkerboard of 6° aperture was placed in this field so as to be integrated into the oculomotor process at different times—at the beginning, during and at the end of the eye movement; (ii) successive horizontal eye movements of 3°, 7° and 11° scanned a checkerboard of 20°, each square of which had a 40′ aperture; (iii) the checkerboard was moved with an amplitude and period similar to those of the eye movements in (ii), but this time with gaze fixed. Horizontal and vertical movements of both eyes were recorded with an EOG. An EEG of the parieto-occipital regions was obtained using eight linked bipolar derivations in line on two montages, median longitudinal and right-left transverse. The EEG and EOG data were digitalized and a numerical programme of waveform recognition was used to identify the beginning of the saccade which triggers the averaging out of the EEG before (100 ms) and after (500 ms) the eye movement. A discussion of the results, taking into account the latency of the different components and their reinforcements or inhibition depending on experimental conditions, suggests that the two initial components of lambda response (including the initial portion of the classical lambda wave) might be due to visual effects (‘off effect’) that arise at the start of the movement or slightly before it at the time that the saccadic suppression begins. The later components could be attributed to visual effects brought into play towards the end of the movement (‘on effect’), when perception becomes normal again. It is, however, difficult to explain some of the results related to the amplitude of lambda components without bringing in a mechanism of non-visual origin (corollary discharge).
Réponses évoquées par le nystagmus spontané
Authors: Lairy Gabrielle C , Lesèvre Nicole , Baillon J F , Rémond A , Godde-Jolly D 
Published: January 2007

A digital programme of wave form recognition was applied to a nystagmogram so as to pave the way for an average chronotopographic study of the occipital EEG activity triggered by the start of the rapid stage of the nystagmus. The programme was used in a clinical case of congenital nystagmus associated with a visual deficiency (coloboma of the optic nerve), with the following results: (i) in the patient examined, no average evoked response was observed either with eyes closed or with eyes open in the dark; (ii) an average response of small amplitude was observed with eyes open centred on a homogeneous illuminated field; this response was reinforced (greater amplitude and more complex structure) by a patterned field (checkerboard); (iii) the response to nystagmus showed characteristics similar to those of lambda response in the same subject. These results appear to confirm the conclusions of Bender and Shanzer (1964) according to which the calcarine activity in monkeys in response to experimental nystagmus is “light and vision dependent and correlates with the visual input and not with the oculomotor output”. Differences in amplitude, latency, and structure between the various responses recorded in the patient examined (response to nystagmus, to appearance of lighted checkerboard, and lambda response) and the same responses in normal subjects are considered and discussed in relation to factors associated with visual deficiency.
Interocular Transfer in Normal Humans, and Those Who Lack Stereopsis
Authors: Movshon J A , Chambers B E I , Blakemore C 
Published: January 2007

Interocular transfer of the tilt aftereffect was investigated in normal humans with good stereopsis and in subjects without stereoscopic vision. These latter subjects were divided into two groups: those with and those without a history of strabismus. Strabismic subjects showed grossly reduced interocular transfer of the effect (12% mean transfer). Nonstrabismic subjects had moderate transfer (49%) and normal subjects showed approximately 70% mean transfer. All normal subjects showed greater transfer from the dominant eye to the nondominant than vice versa. The results are discussed with respect to developmental effects in the visual system of cats and humans, and the nature of the tilt aftereffect.
The Locus of Adaptation to Auditory—Visual Conflict
Authors: Radeau Monique 
Published: January 2007

The site of adaptation resulting from exposure to spatially discordant visual and auditory cues was determined by comparing, for both sensory modalities, shifts in pointings with shifts in estimations of ‘straight ahead’. The exposure task consisted of monitoring a synchronous series of flashes and noises separated 15° laterally by prisms. The shifts it produced for both modalities were of nearly equal magnitude in the two tests. The results suggest that auditory–visual conflict is resolved through recalibrations at the level of sound–head and of eye–head articulations.
An Investigation of Dynamic and Static Visual Acuity
Authors: Fergenson P E , Suzansky J W 
Published: January 2007

The effect on dynamic visual acuity (DVA) of target angular velocity ω and target exposure time te was examined. The correlation between DVA and static visual acuity (SVA), the ability to discriminate small spatial separations in a stationary target, was also determined. DVA was measured for pairings of four values of ω (25, 30, 40, and 45 deg s−1) with four values of te (0·4, 0·6, 0·8, and 1·0 s). The twenty-four subjects viewed Landolt-ring targets that were presented as slide projections on a rear-projection screen. The average thresholds for each condition were determined and compared. SVA was measured and correlated with the DVA scores for each condition. The results indicated that: (i) DVA deteriorated for increased ω or decreased t, with the latter having the most significant effect, (ii) DVA and SVA were not significantly correlated, (iii) the experimental apparatus and procedure were highly reliable, and (iv) DVA improvement with testing was significant for some conditions.
Human Perception of Homogeneous Dot Patterns
Authors: O'Callaghan J F 
Published: January 2007

Experiments were conducted to ascertain human performance at clustering relatively homogeneous dot patterns. Two methods for clustering a rectangular array of dots into two halves were studied: one increased the separation between the left and right halves, and the other increased the density of one of the halves. Significant effects were found for array height on the perception of ‘separation’ patterns, and for overall dot density on the ‘density’ patterns. The results indicate that global properties of dot patterns affect the immediate perception of clusters, and consequently attempts to simulate human perception must incorporate the processing of such global properties. The results also indicate that different perceptual processes operate on dot proximity in perceiving the two kinds of pattern. It is suggested that these processes are in fact complementary: one detects perceptual edges, while the other groups areas of similar dot density.
Movement Aftereffects Contingent on Binocular Disparity
Authors: Anstis S M , Harris J P 
Published: January 2007

Five subjects adapted for 30 min to a textured disc lying in front of the fixation point with 0·1 deg(1) crossed disparity, which rotated clockwise at 4 rev/min, alternating with a disc behind the fixation point, with 0·1 deg of arc uncrossed disparity, which rotated anticlockwise. A stationary test field then appeared to rotate anticlockwise when it lay in front of the fixation point, and clockwise when it lay behind. Conversely, a test field in the plane of fixation briefly appeared to lie a few millimetres behind the fixation plane when it rotated clockwise, and in front when it rotated anticlockwise. The movement aftereffect contingent on disparity reappeared each time the test disparity was reversed, but the total duration of each successive aftereffect in the series decreased exponentially with elapsed time. Movement aftereffects contingent on disparity were very much stronger than those contingent on colour and won out over them when disparity was pitted against colour.
Diphasic and Polyphasic Temporal Modulations Multiply Apparent Spatial Frequency
Authors: Virsu V , Nyman G , Lehtiö P K 
Published: January 2007

The effects of diphasic and polyphasic flicker on apparent spatial frequency were studied in several experiments through simultaneous spatial-frequency matches. In diphasic flicker the spatial phase of a sinusoidal grating alternated between two values in a counterphase fashion, and in polyphasic flicker the spatial phases of gratings were varied discretely in time in a variable number of steps. Both forms of flicker increased the apparent spatial frequency at low temporal frequencies, in the same manner as low-frequency monophasic flicker has been found to do. At high temporal frequencies, diphasic flicker doubled the apparent spatial frequency, as reported by Kelly (1966). We found that through high-frequency polyphasic flicker the spatial effect that Kelly mentions can be generalised to spatial frequency multiplication: polyphasic flicker produces not only the apparent second harmonic but also the third and the fourth harmonic, depending on the phase parameters. A numerical analysis showed that the spatial high-frequency effects can be explained through temporal integration of nonlinearly filtered input signals if a value of 200 td(1) is assumed for the nonlinearity constant in [Formula: see text] where B( I) is the brightness, I is the retinal illuminance, K is a scale constant, and I½ is the constant of nonlinearity. A minimum value of 60 ms had to be estimated for integration time. An investigation of the integration time with diphasic flicker indicated that spatial integration time decreases when the level of light adaptation increases, and that the integration time for spatial effects is longer than for flicker fusion. The spatial effects of low-frequency and high-frequency flicker differ in so many respects that different neural processes have to be postulated for their explanation.
Dark Adaptation and Short-Wavelength Backgrounds Decrease Perceived Size
Authors: Virsu Veijo , Vuorinen Risto 
Published: January 2007

The effects of background luminance, contrast, and background wavelength on the perceived size of small line figures were studied at mesopic levels of light adaptation. Perceived size diminished at low levels of background luminance. The effect disappeared at high levels of luminance. Perceived size of luminous circles increased as a logarithmic function of background luminance when the background intensity did not exceed 25 td(1). The strength of the size effect decreased as a function of circle diameter from 0·125 to 2 deg of visual angle(2). Perceived size of small luminous circles, subtending less than 0·5 deg, also increased as a function of contrast at low values of contrast but at very high values of contrast there was a decrease in perceived size. Background luminance had the same effect on the perceived size of circles as on the perceived size of spatial cycles in gratings. Control experiments led to the conclusion that dark adaptation is the primary source of the size effects. The main evidence for this conclusion was obtained from a demonstration that the same background luminance produced either an increase or a decrease in perceived size, depending on the adaptational state of the eye. It was also found that a shift from cone vision to rod vision contributes to the effects, for a stimulus looked smaller on a short-wavelength background than on a long-wavelength background. The size effects can be predicted from the changes of receptive-field properties of single neurones under corresponding conditions of stimulation, if it is assumed that the perception of size is mediated by size-specific channels formed of single neurones. Stimulation that leads to an activation of small receptive fields appears to indicate to the brain the presence of small retinal images. If small receptive fields are experimentally made responsive to larger retinal images, an underestimation of size results.
The Microstructure of Dual Task Interaction. 3. Incompatibility and Attention Switching
Authors: Fisher Shirley 
Published: January 2007

This report is the third in a series of reports concerned with close analysis of a dual task situation in which a five-choice serial task is combined with an auditory—verbal response task. A situation is described in which ‘incompatibility’ is incorporated into the five-choice task in order to increase the information processing load and thus explore the effect on the mechanism believed to control the microstructure of the time-sharing process. Results supported the notion that subjects were continuing to operate a sequential processing strategy in combining the two tasks. The structure of the interval generated by the occurrence of the auditory-verbal task was different in comparison with the compatible five-choice condition reported earlier, suggesting that the introduction of incompatibility causes a change in the characteristics of the time-sharing process. The structure of the interval remained organised and consistent, suggesting that the mechanism which controlled the time-sharing process was not disrupted by increased main task load and therefore was likely to involve a process which did not compete for attention space with task variables. Results also revealed an effect of the digit task response on the following two serial responses. It was suggested that these were probably best described as two independent effects: one arising from the sequential processing strategy adopted, and the other arising perhaps as a function of perception of overall task difficulty.
The Angular Function of Orientation Illusions Induced by Projected Images of Tilted Real Object Scenes
Authors: Purcell Terry , Wenderoth Peter , Moore David 
Published: January 2007

Tilt aftereffects induced by line gratings are maximal when the test and inducing stimuli have an angular separation of 10°–15°. Similar effects induced by prismatically tilted real-object scenes have been found to increase monotonically with scene tilt. The difference between these two angular functions of aftereffect (that induced by gratings and that induced by real objects) has been attributed to the ‘meaning’ inherent in the real-object scenes. The preliminary experiments described here suggest that tilt aftereffects and illusions induced by projected slides of tilted real-object scenes have angular functions similar to that induced by a line grating. Hence, the monotonically increasing angular function obtained in the prism studies is not necessarily determined by the use of real-object scenes.
Optical Defocusing Reverses Perceptual Organization
Authors: Petersik J Timothy 
Published: January 2007

At a certain point during the defocusing of a reversible figure, the organization of the figure reversed unexpectedly, and the reversal seemed more abrupt than a spontaneous reversal. The critical point is approximately constant over time for a given subject, and a similar point occurs during refocusing. This phenomenon is discussed in terms of inhibition between competing neural structures.
The Microstructure of Dual-Task Interaction. 4. Sleep Deprivation and the Control of Attention
Authors: Fisher Shirley 
Published: January 2007

The experiment was designed to investigate attention-switching behaviour in sleep-deprived subjects and involved the same dual-task paradigm reported in earlier studies. The task specified by instructions to be the main task, was the five-choice serial-response task; the secondary task was an auditory-verbal digit task which occurred at random time intervals. Analysis of the intervals in which the two tasks concurred gave a different result. Sleep-deprived subjects seemed less able to control the fine structure of the interval and tended to persist in producing serial responses at the expense of the secondary-task response. The evidence supported the view that both sleep-deprived and control subjects were not able to process information in parallel and, thus, the difference in interval patterning was due to the difference in attention-switching processes. The possibility that sleep deprivation might result in loss of attentional control is considered briefly. A surprising result was that, in terms of overall response rates, the sleep-deprived group, although slower, preserved the dual-task priority structure better than the control group, who slowed on both tasks in the combined condition. The control result was different in this respect from control data from previous research, but it is important that within the sleep-deprived group there was evidence that ability to preserve the priority structure was unaffected.
The Many Illusions of the Müller-Lyer: Comparisons of the Wings-in and Wings-out Illusions and Manipulations of Standard and Dot Forms
Authors: Greist-Bousquet Suzanne , Schiffman Harvey R 
Published: January 2007

The assumed role of peripheral distortion mechanisms in both wings-in and wings-out Müller-Lyer illusions was investigated by requiring subjects to reproduce the central extent of standard Müller-Lyer figures and dot variations. Illusory magnitude of the line and dot variations was also examined with increasing wing length and wing angle. A reduction in the overestimation for the wings-out illusion occurred with the removal of intersecting lines; the dot variations evidenced a significant overestimation effect. In contrast, no reliable decrease in underestimation was found with the removal of intersecting lines in the wings-in illusion, and both standard and dot variations were significantly underestimated. These results support a conclusion that the wings-in and wings-out Müller-Lyer illusions are two distinct illusions, and may be differentially determined at the loci of distortion within the visual system. Parallel changes in illusory magnitude were noted with configural manipulations of standard and dot wings-out illusions. However, standard and dot forms of the wings-in illusion were not equivalently affected by equivalent configural manipulations, which suggests that they are different illusions. Thus, the use of the wings-in dot variation to separate empirically peripheral from nonperipheral distortion mechanisms may be ill-advised.