[Post-cannulation purulent thrombophlebitis of the inferior vena cava: preoperative diagnosis using CT and successful surgical treatment].
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Catheterization↗
Biomedical subjects
J Bures
Publications and source records attributed to J Bures.
Disruptive effects of lateral hypothalamic stimulation on the lick-interrupt cycle in rats.
Consummatory licking at a water spout was compared with licking at a dry spout maintained by electrical hypothalamic stimulation in the same rats. Both forms of licking, recorded photoelectrically, were maintained on a fixed ratio 8 schedule. Duration of reinforcement delivery was equated [300 ms]. A computer analysis of the temporal distribution of licks in each 1024 ms period from onset of reinforcement revealed that lateral hypothalamic stimulation decreased the occurrence of licking and disrupted the normally synchronous pattern of this behaviour. An analysis of the effects of delivering lateral hypothalamic stimulation contingent on water-maintained licking revealed that this effect of stimulation was clearly current-dependent. It is proposed that differences in licking rates maintained by water and by electrical hypothalamic stimulation, respectively, are due to response interference in the latter case. This interference effect is also proposed to be a major factor underlying higher reward thresholds for self-stimulation when licking is the operant response.
Animals↗
Hippocampal slice (K+)e: depth profiles and changes induced by stimulation or anoxia.
In an attempt to develop a technique which would allow early assessment of the functional state of explanted brain tissue, (K+)e was measured in the CA1 region of rat hippocampal slices using K+-selective microelectrodes. In slices (450 micron) maintained at the boundary between the incubation medium and 95% O2/5% CO2 atmosphere, (K+)e was highest (up to 25-30 mmol/l) immediately below the exposed surface and gradually decreased with depth to (K+) of the bathing fluid (5 mmol/l). (K+)e below the exposed surface remained high throughout the 2 h of incubation. In submersed slices, (K+)e was the highest in the center of the slice (200 micron, 10 mmol/l) and decreased towards both surfaces. During 2 h incubation, (K+)e decreased in the center of the slice to 6 mmol/l in viable preparations remaining high in the deteriorating ones. Electrical stimulation of Schaffer's collaterals (15 V; 0.2 ms; 10 Hz) increased (K+)e of viable slices 200 micron below the surface by 2-3 mmol/l. Similar but slower (K+)e changes were elicited by brief (3 min) anoxic episodes (perfusion with incubation medium equilibrated with 95% N2/5% CO2). It is concluded that submersed slices have a more uniform (K+)e profile as compared to the exposed ones and that low (K+)e in the early phase of incubation is a good predictor of slice viability.
Animals↗
Hippocampal afterdischarge interferes with storage of spatial information in a working memory test.
In an attempt to impair spatial working memory by reversible functional blockade rather than by irreversible lesion of the hippocampus, eight male hooded rats were trained to asymptotic performance of 1.2 to 1.4 errors per trial in the spatial 12-choice apparatus ( Bure s et al. 1982), formally similar to the radial maze. The rats were implanted with hippocampal stimulating and recording electrodes, which were used for eliciting and monitoring hippocampal afterdischarge (HAD) lasting for at least 20 s. In Experiment 1, HAD elicited 1 or 10 min before testing increased the incidence of errors to 2.75 or 2.50 per trial, respectively, but the performance still remained above chance level (4.18). In Experiment 2, interruption of the trial by 1, 10, 20 and 30 min intervals inserted between choices 6 and 7 increased the incidence of errors in choices 7 to 12 to 1.0, 1.5, 2.1 and 2.5, respectively. HAD elicited immediately after choice 6 increased error incidence in the subsequent 6 choices performed after 1-min or 10-min intervals to 3.1 or 2.75, respectively, i.e. to the chance level of 3 errors in 6 choices. It is concluded that HAD elicits transient shortening of the memory span for newly acquired spatial information (anterograde effect) and erases the current spatial working memory record (retrograde effect).
Action Potentials↗
Caudate stimulation prolongs latency of acoustically and visually signalled reaching in rats.
Latencies of acoustically and visually signalled lateralized ballistic reaching were examined in rats with implanted electrodes in the caudate nuclei (Cd). Single pulse stimulation of Cd coinciding with CS onset increased the reach latency from 180 to 300 ms. Stimulation of Cd contralateral to the preferred forepaw was more disruptive than stimulation of ipsilateral Cd and the interference threshold was lower for Cd stimuli applied 100 ms after CS onset. Since reaching latencies were only moderately prolonged (by 85 ms) after electrolytic lesion of ipsilateral dentate nucleus. Cd stimulation does not only disrupt cerebellar preprogramming, but has a more general interfering effect.
Animals↗
Spiral waves of spreading depression in the isolated chicken retina.
Existence of the theoretically predicted spiral waves of excitation in intact two-dimensional networks of excitable elements has been experimentally confirmed in the isolated chicken retina. The preparation supports the waves of Leão's spreading depression (SD) the concentric propagation of which from the point of origin can be directly observed as a change of the optical properties of the retinal tissue. The propagation rate of 3.7 mm/min (35 degrees C) decreased to 1.5 mm/min for SD waves elicited during relative refractory period. When a several-mm long segment of the SD wave had been blocked by anodal polarization, the laterally opened ends of the wavefront started to spread after termination of polarization into the previously blocked tissue, gradually turning around and penetrating into the region recovering from the original SD. One or two simultaneously generated spiral waves of SD continued to rotate for several cycles. Spiral SD could also be elicited by punctiform cathodal polarization (1 mA) applied to the SD wave-rear. Since the new SD wave could only spread into the recovering tissue it formed a laterally open wavefront, the free ends of which eventually turned around and started spiral SD. With continued reverberation the nucleus of the spiral SD wave gradually migrated across the retina until it approached an obstacle (e.g., pecten) which stopped further spiral propagation. Spiral SD waves were elicited in 31 retinal preparations and lasted for 4.5 cycles on the average. Average cycle duration was 4.7 min. Spontaneous spiral SD waves were observed in preparations incubated in Mg2+-free media. The spiral SD waves in retina are compared with mathematical models of analogous phenomena. It is argued that spiral SD waves probably exist in the cerebral cortex of rats and account for generation of repetitive SD waves sometimes elicited by overlapping stimulation of two cortical regions.
Animals↗
Cortical penicillin focus as a generator of repetitive spike-triggered waves of spreading depression in rats.
Epileptic foci were established by application of Na-penicillin on the exposed parietal cortex of rats (n = 66) anesthetized with pentobarbital. Spikes appearing after a brief (greater than 30s) spontaneous interruption of the interictal discharge were sometimes followed by a spike-triggered spreading depression (STSD) wave, which blocked the activity of the focus for several min. The first recovering spike induced another STSD and repetitive STSD generation continued for up to 20 cycles, with a median cycle duration of 6 min. STSDs appeared more regularly after postictal depression induced by electrical stimulation of the focus or of the symmetrical brain area, and could also be elicited by SD waves evoked by microinjection of 5% KCl into extrafocal cortical regions. An ongoing STSD cycle was interrupted when another penicillin focus in the contralateral hemisphere started to trigger the focal discharge during relative SD refractoriness. STSD waves were observed in 42% of the animals. Attempts to elicit STSD were successful in 70% when the interictal discharge rate was low (less than 10/min) but mostly failed with higher discharge rates (greater than 30/min). It is suggested that STSD is generated when an isolated epileptic spike appears at the level of decreased potassium clearance and that repetitive STSDs are produced by synaptically and metabolically mediated interaction between focal discharge and spreading depression.
Animals↗
A telerecording analysis of reaching disruptions in rats after stimulation or lesion.
In the so-called "handedness" experiments rats learn to retrieve food pellets from a narrow tubular feeder preferentially with the left or right forepaw. Frame-by-frame analysis of videotape recordings showed that the stereotype movement consists of a fast forepaw extension (54 msec), followed by isolated finger flexion (46 msec) overlapping later with slow forelimb retraction (180 to 400 msec). Reach-triggered single pulse stimulation of contralateral caudate nucleus or ipsilateral dentate nucleus interfered with finger flexion and disorganized the time course of the movement. Electrolytic lesion of the ipsilateral dentate nucleus caused marked slowing of the extension (80 msec) and finger flexion (140 msec) phases of the movement. Videoanalysis confirms the ballistic character of the initial phase of the reaching movement.
Animals↗
Differential effects of d,l-amphetamine on licking maintained by electrical hypothalamic stimulation and/or water in rats.
The role of the reinforcer as a determinant of the behavioural effects of amphetamine was assessed with a procedure under which response requirements were equated. Eight rats were trained to lick on fixed-ratio schedules of rewarding lateral hypothalamic stimulation and water delivery, respectively. The effects of d,l-amphetamine (0.2-2.0 mg/kg) were investigated in the lateral hypothalamic stimulation condition and compared with the effects of the drug at 1.0 mg/kg in the water condition. Licking maintained by hypothalamic stimulation was increased after amphetamine administration to approximately 200% of control performance at 1.0 mg/kg. At this dose amphetamine administration resulted in a decrease in water maintained licking. A computer analysis of the temporal patterning of licking in both water and stimulation conditions was carried out. This analysis revealed that amphetamine may attenuate the disruptive effects of hypothalamic stimulation on the lick-interrupt cycle. The differential effects of amphetamine on licking maintained by the two events may reflect either unequal participation of catecholaminergic circuits in the two types of reward, or anti-inhibitory motor effects of amphetamine.
Amphetamine↗
Cortical spreading depression blocks naloxone-induced escape behaviour in morphine pretreated mice.
Mice treated with morphine (100 mg/kg SC) and 3 hr later with naloxone (30 mg/kg) developed an acute abstinence syndrome characterized by escape attempts (rearing, wall-climbing, jumping) and unconditioned motor (head-shaking, jerking) and visceral signs. Functional decortication by spreading depression (SD), elicited 15 min before naloxone injection by epidural application of 25% KCl, abolished the escape behaviour without interfering with other abstinence signs. Electrophysiological recording confirmed reliable generation of cortical SD waves under the conditions of the experiment. The SD effect indicates that the escape behaviour of morphine dependent mice is a conditioned compensatory response to the unconditioned effects of the drugs.
Animals↗
An attempt to account for controversial estimates of working memory persistence in the radial maze.
Factors affecting performance in the radial maze were examined to explain widely differing estimates of the persistence of spatial working memory. In Experiment 1, two groups of 10 rats each, trained in the 8-arm elevated maze (EM) or two-level maze (TLM), showed after 30 trials 0.66 and 0.34 errors per eight choices, respectively. In Experiment 2 insertion of a delay between choices 4 and 5 increased error incidence in choices 5 to 8 from 0.8 and 1.0 at 2-min delay to 1.8 and 1.9 at the 1-hr delay in the EM and TLM, respectively. (Chance level is 2.0 errors in choices 5 to 8). In Experiment 3, omission of the masking food odor sources improved performance in the EM at the 1-hr (1.1 error) but not at the 4-hr delay (1.85 error). In Experiment 4, elimination of trail marking by replacement of maze A, used in choices 1 to 4, by maze B in choices 5 to 8 caused a significant deterioration of delayed performance in the TLM but not in the EM. In Experiment 5, a continuous series of 15 trials with the 40-min delay improved performance in the EM from 1.60 to 1.35 errors in choices 5 to 8. High error incidence (0.41) on choice 5 was due to rat's preference for channels visited on choices 1 and 2. Significant decrease of errors on choice 6 (to 0.25) indicates that the rats responded to incorrect choice 5 by activation of an error-correcting strategy. Examples of such strategies are given which increase delayed performance well above chance level even in the absence of working memory. Error-induced change of response pattern is indicated by the observation that the interchoice distances 1--2 and 5--6 are the same after correct, but differ by 0.83 channel after incorrect choice 5. Possible reasons for the failure to confirm the long persistence (more than 4 hr) of spatial working memory reported by Beatty and Shavalia (Behavioral and Neural Biology, 28, 454--462, 1980) are discussed. It is argued that longevity of the working memory record gives the rat no advantage in foraging and must be, therefore, carefully checked against possible alternative explanations.
Animals↗
Cortical spreading depression and conditioned taste aversion: an attempt to resolve a controversy.
The claim (Winn, Todd, & Elias, Behav. Biol. 19, 55-63 (1977) ) that cortical spreading depression (CSD) can serve as US in the conditioned taste-aversion (CTA) paradigm was experimentally examined. Rats given 15-min access to novel 0.1% sodium saccharin (CS) followed by ip NaCl and bilateral or unilateral CSD (US) displayed similar saccharin preference (54%) as the sham-CSD-treated controls in a multiple-bottle retention test. Rats receiving ip LiCl (0.15 M, 2% body weight) and sham CSD as the US showed marked saccharin aversion. It is concluded that CSD does not elicit CTA and that some claims to the contrary can perhaps be ascribed to CSD-induced disruption of attenuation of neophobia.
Animals↗
[Colicinogens in nonspecific intestinal inflammation. I. Colicinotypes in patients with ulcerous colitis, Crohn's disease and in healthy individuals].
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Adult↗
[Colicinogens in nonspecific intestinal inflammations. II. Test of leukocyte migration inhibition with colicins].
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Adult↗
Specificity of the effect of desglycinamide (8-D-arginine) deaminovasopressin on short--term memory.
The effect of desglycinamide (8-D-arginine) deaminovasopressin (desgly NH2 dDAVP) on learning was studied in rats using the conditioned taste aversion (CTA) paradigm. Desgly NH2 dDAVP (3 micrograms/kg) applied 40 min before presentation of the gustatory CS (0.1 % saccharin) did not affect CTA formation, when the visceral US (0.15 mol/l LiCl, 2 % body weight) was applied after a 1 h delay. With 2 h CS-US delay the same dosage of the peptide caused CTA impairment, manifested by weaker and faster decaying aversion to saccharin. The above effect of the peptide was blocked by post-CS anesthesia (pentobarbital 40 mg/kg). It is suggested that desgly NH2 dDAVP affects learning indirectly, by increased arousal interfering with the persistence of the short-term gustatory traces in the relatively long CS-US interval.
Animals↗
[Smoking habits in patients with nonspecific intestinal inflammation].
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Adult↗
Radial maze as a tool for assessing the effect of drugs on the working memory of rats.
The effect of physostigmine (0.2 mg/kg), scopolamine (0.1 mg/kg), d,l-amphetamine (1 mg/kg), apomorphine (0.05 mg/kg), and piracetam (100 mg/kg) on working memory was examined in 12 rats that were highly overtrained in the radial maze. In experiment 1, drugs administered 10 min before the trial did not worsen performance of rats in the 12-arm maze. In experiment 2, insertion of a 5-min delay between the sixth and seventh choices increased the number of errors over choices 7-12. Performance was unaffected by pretreatment with physostigmine or apomorphine, but was significantly impaired by scopolamine, amphetamine, and piracetam. In experiment 3, performed in a 24-arm maze, the number of errors and trial duration increased, but performance was not decreased by amphetamine or piracetam. It is concluded that the uninterrupted radial maze task is relatively resistant to pharmacological disruption, but that scopolamine, amphetamine, and piracetam enhance the effect of stimuli interfering with the storage of spatial information over delays.
Amphetamine↗
A multiple choice apparatus for electrophysiological investigations of spatial working memory in rats.
A multiple choice apparatus, minimizing the rat's movements and thus simplifying brain stimulation and/or recording in working memory experiments, consists of a dodecagonal enclosure (30 cm diameter, 100 cm high) with a horizontal platform assuming either an upper or a lower position, 43 or 65 cm below the top of the wall, respectively. The platform is moved between these two levels by a pneumatic system controlled by solid-state programming circuits. Each wall segment contains a choice window, 7 cm above the upper floor level, providing access to a recessed feeder. When the platform with a food-deprived rat moves into the upper position, the animal opens the hinged shutter of one window and gets the pellet. Five seconds later, a self-locking relay marks the visited window and the floor descends to the low position where it remains for a predetermined interval (e.g. 20 s), until it is raised again. The above cycle repeats as a long as different windows are chosen. When a choice is directed to an already visited window (error), the floor returns to the low position at once. During one trial, the animal is allowed 12 choices and the number of errors (i.e. choices directed to already entered windows) is recorded. In spite of the great reduction of kinaesthetic and vestibular signals and the almost complete elimination of visual extramaze cues, the working memory performance is similar to that in analogous radial maze.
Animals↗