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J Bures

Publications and source records attributed to J Bures.

At least 55 records · Page 3Linked to original sources
PubMed2000

[Possibilities in the diagnosis of Helicobacter pylori].

The authors present an overview of current possibilities of the diagnostics of Helicobacter pylori (HP) focused on non-invasive methods. The overview is based on author's own experience and studying of applicable literature. Non-invasive methods (endoscopy is not needed) include serology (blood tests) and breath tests. Both methods are compared one with the other (and with invasive methods as well) not only from the point of view of sensitivity and specificity, but especially from the point of view of their practical use and correct indication of their use. 13C urea breath tests are non-invasive global tests with 100% reproducibility, high sensitivity and specificity. It is possible to pursue them everywhere and send them by post for processing. The analysis time for one breath sample is within 60 seconds. Breath tests are the gold standard of diagnostics of HP and if only one test is used, they are the best way of verifying the success of eradication therapy, of examination of children and pregnant women and of implementing the population studies.

Breath Tests↗
PubMed1999

Hippocampal damage induced by carbon monoxide poisoning and spreading depression is alleviated by chronic treatment with brain derived polypeptides.

A model of acute carbon monoxide poisoning combined with spreading depression (SD) induced metabolic stress was used to examine the protective effects of cerebrolysin (CL) on the development of electrophysiological, behavioral and morphological signs of hypoxic damage. Capillary electrodes were implanted into the neocortex and hippocampus of anesthetized rats which were then exposed for 90 min to breathing of 0.8% to 0.5% CO, while 3 to 4 waves of cortical and hippocampal SD were elicited by microinjections of 5% KCl. Duration of SD-provoked depolarization of cerebral cortex and hippocampus was noted. Nine and 18 to 19 days later propagation of SD waves was recorded with the same electrodes and decrease of their amplitude was used as an index of brain damage which was significant in the hippocampus but not in the cortex. CL-treatment (2.5 ml/kg per day) started after CO administration and continued for 14 days significantly improved hippocampal recovery manifested by increased amplitude of SD waves. Behavioral tests performed 10 and 20 days after CO poisoning in the Morris water maze revealed better performance (escape latency 7 s) in the CL-treated than in untreated animals (14 s). Morphological analysis showed marked damage in the hippocampus consonant with electrophysiological and behavioral findings in the same animals. No apparent histological damage was found in rats exposed to CO inhalation alone without the additional SD-provoked depolarization. It is concluded that chronic CL-treatment enhances recovery of hippocampal tissue after hypoxic damage of intermediate severity.

Acute Disease↗
PubMed1999

Protein abundance alterations in matched sets of macroscopically normal colon mucosa and colorectal carcinoma.

Our current results, aimed at the detection of protein abundance alterations that could be associated with the process of colon tumorigenesis, are summarized. The matched sets of macroscopically normal colon mucosa and colorectal carcinoma were examined by a one- or two-dimensional electrophoretic approach and proteins were identified using immunoblotting or mass spectrometry. The following results were observed: The levels of liver fatty acid-binding protein, actin-binding protein/smooth muscle protein 22-alpha and cyclooxygenase 2 were downregulated in colorectal carcinoma compared to normal colon mucosa. Conversely, the expression of a novel variant of heat shock protein70 and several members of the S100 protein family of calcium-binding proteins (two isoforms of S100A9, S100A8, S100A11 and S100A6) were upregulated in transformed colon mucosa. Despite the variations of the levels of expression of given protein among analyzed samples, all quantitative changes were found to be statistically significant (Mann-Whitney test assuming p < or = 0.05). We conclude that the proteomic approach is useful for the study of complex biological events underlying the process of colorectal tumorigenesis.

Colon↗
PubMed1999

Place navigation in rats guided by a vestibular and kinesthetic orienting gradient.

The role of the slope of terrain in orientation was examined in rats trained to find, among 4 equidistant feeders, the 1 located in the upper left quadrant of a 10% tilted arena (1-m radius). Rats started from the center in light and with randomly changing slope direction reached the correct goal in 90% of 1st choices after 29 sessions. The same rats maintained 83% correct choices when the experiment was conducted in darkness. On a horizontal arena, their performance became random. After training, successful navigation was also observed (71% correct 1st choices) when the rats were started from different points at about 30 cm from the wall. This finding suggests that the slope of terrain may be used to establish a cognitive map based primarily on kinesthetic and vestibular signals. The flexibility of such a map seems to be rather limited, however, because changing the goal position with respect to inclination requires prolonged retraining.

Analysis of Variance↗
PubMed1999

A relationship between K-ras gene mutations and some clinical and histologic variables in patients with primary colorectal carcinoma.

Mutations in the Kirsten ras 2 (K-ras) gene were described as early events in the process of colorectal carcinogenesis. The aim of this study was to find a possible relationship between the presence of K-ras mutation in samples of primary colorectal carcinomas and the clinico-pathological data of the investigated patients. Mutation in codon 12 of the K-ras gene was determined in 18 of 53 colorectal carcinomas (34%) in our group of patients. The presence of K-ras gene mutations was not related to gender, age of subject at diagnosis, staging or cancer location (p > 0.05). Sixteen of the 42 (38%) moderately differentiated carcinomas, and two of the eight (25%) well differentiated carcinomas contained K-ras mutation in codon 12, but none of the three poorly differentiated carcinomas contained the mutation. Moderately differentiated tumours contained an aspartate code GAT (in eight cases), a valine code GTT (in six cases), an alanine code GCT (in one case) and a serine code AGT (in one case) in codon 12. Well differentiated tumours contained only the valine code GTT (two cases). Our results show that the frequency of mutations in the K-ras gene in carcinomas in Central Europe is not different from the frequencies found in other parts of the world. The homogeneous incidence of K-ras mutation does not seem to be related to ethnic factors, dietary habits, or the composition of the diet.

Adult↗
PubMed1999

[Thyrotoxicosis due to long-term therapy with interferon alpha in the patient with mixed chronic active hepatitis B and C].

The authors describe a case report of 48-year-old woman treated with Interferon alpha for the chronic active hepatitis B and C. During this therapy thyrotoxicosis occurred. It disappeared after the withdrawal of Interferon alpha and administration of strumigens. Immediately after stopping of the administration of Interferon alpha and three month later antibodies against the thyroid epithelium were found.

Antiviral Agents↗
PubMed1998

Both here and there: simultaneous expression of autonomous spatial memories in rats.

Foraging rats learned to avoid footshock that was present in a part of a circular arena that was either stable or rotating slowly in a lighted room. The rotation dissociated spatial information in the separate reference frames of the room and arena. After learning to avoid the shocked region in either condition, in the absence of shock, memory for this place was expressed by simultaneous avoidance of an area defined in the reference frame of the room as well as of an area defined in the reference frame of the rotating arena. Spatial memories in these distinct reference frames were acquired, retrieved, and extinguished autonomously.

Animals↗
PubMed1998

[Helicobacter pylori CagA antigen antibodies].

BACKGROUND: CagA antigen of Helicobacter pylori is highly immunogenic in humans. There is an increasing evidence that infection with CagA-positive strains is related to the development of peptic ulcer disease, atrophic gastritis, or gastric cancer. The aim of our study was to assess seropositivity to CagA in a group of 95 clinically symptomatic adults who underwent gastroduodenoscopy and to correlate results to their disease characteristics. METHODS AND RESULTS: Serum immunoglobulin G antibodies to CagA detected by ELISA kit (Helicobacter p120, Viva Diagnostika, Germany) were compared to standard IgG specific antibodies against a pool of H. pylori antigens Synelisa Pin plate, ELIAS, Germany). Immunoglobulin G antibodies to CagA were present in 5/31 (16%) serum samples from H. pylori negative persons and 10/28 (36%) serum samples from H. pylori positive patients without peptic ulcer disease compared with 8/11 (73%) H. pylori positive patients with peptic ulcer disease in the past, 11/13 (85%) H. pylori positive patients with duodenal ulcers or duodenitis and 4/5 (80%) H. pylori positive (1/7, 14% H. pylori negative) serum samples from patients with gastric resection for peptic ulcers in the past. Serum levels of antibodies to CagA in the groups of patients with peptic ulcer disease in the past, with present duodenal ulcers of duodenitis and in H. pylori infected patients with gastric resection were significantly higher then those of H. pylori infected patients without peptic ulcer disease (P < 0.05). On the other hand, there was no significant difference in the presence of the specific antibodies against at pool of H. pylori antigens between these four groups. CONCLUSIONS: These data suggest that serologic response to the CagA antigen is more prevalent in H. pylori positive persons with present or past peptic ulceration than among infected persons without peptic ulcer disease. The presence of antibodies to CagA in H. pylori positive persons may be useful for the identification of patients with higher risk or more severe disease.

Adolescent↗
PubMed1998

The effect of MK-801 and of brain-derived polypeptides on the development of ischemic lesion induced by photothrombotic occlusion of the distal middle cerebral artery in rats.

The effect of neuroprotective drugs on the early and late electrophysiological manifestations of photothrombotic occlusion of distal branches of middle cerebral artery was studied in rats treated with MK-801 and Cerebrolysin (CL). DC potentials were recorded from the irradiated cortex (ischemic core), from the adjacent penumbra zone and from remote intact cortex. Irradiation elicited after a few minutes of spontaneous spreading depression (SD) waves followed during 10-15 min by focal ischemic depolarization (FID) developing in the irradiated cortex and spreading into the perifocal areas. While the core FID amplitude reached about 30 mV and decayed during subsequent 2 h to 10-13 mV, FID in the penumbra zone was broken by periods of partial repolarization and returned during 30-90 min almost to baseline. At the same time, generation of spontaneous SD waves almost stopped. MK-801 (0.5 mg/kg, i.p., 45 min after ischemia) blocked SD waves, but did not shorten penumbra FID, the decay of which was slowed down to the rate found in the ischemic core. CL treatment (2.5 ml/kg, i.p. , 1 h after ischemia) did not influence FID in the acute phase of the experiment, but its 10-day administration facilitated post-ischemic recovery indicated by higher amplitude of evoked SD waves penetrating into the former penumbra zone. Morphological examination showed that the volume of total and partial necrosis was increased in the MK-801 group and marginally reduced in the CL group. It is suggested that the absence of the SD-induced hyperperfusion episodes in MK-801-treated rats may accelerate perifocal thrombotization in this model of focal ischemia.

Amino Acids↗
PubMed1998

Tetrodotoxin inactivation of the gustatory cortex disrupts the effect of the N-methyl-D-aspartate antagonist ketamine on latent inhibition of conditioned taste aversion in rats.

The effect of the non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist ketamine on latent inhibition of taste aversion learning was studied in rats. Systemic injections of ketamine (50 mg/kg) applied after each of three preexposures to sodium saccharin (0.1%) disrupted the latent inhibition effect. The blockade was not due to aversive properties of ketamine, because three saccharin-ketamine pairings did not produce saccharin aversion. Moreover, the ketamine-induced blockade of latent inhibition was disrupted by tetrodotoxin injections (10 ng/microl)-induced reversible inactivation of gustatory cortex, applied after each preexposure. A specific gustatory cortex mediation of the ketamine effect is discussed.

Animals↗
PubMed1998

Lateralized fascia dentata lesion and blockade of one hippocampus: effect on spatial memory in rats.

Unilateral blockade of the dorsal hippocampus by tetrodotoxin makes it possible to form lateralized spatial memories, which rapidly transfer to the naive hippocampus when training continues with intact brain. Unilateral X-ray irradiation of newborn rats causes irreversible destruction of granule cells in the ipsilateral fascia dentata (FD). Possible compensation of poor learning in the lesioned hemisphere by commissural transfer of memories from the intact hippocampus was examined in seven rats with unilateral FD lesion, which were first trained in the Morris water maze to asymptotic performance (mean escape latency 6+/-1 s). Subsequent testing during functional ablation either of the intact or of the lesioned hippocampus by tetrodotoxin revealed escape latencies 35+/-8 s or 8+/-1 s, respectively. Probe trial tests during inactivation of the intact and lesioned hippocampus showed target quadrant preference of 32+/-2% or 54+/-3%, respectively. The results indicate: (a) that one intact hippocampus alone can support the water maze task, (b) that no, or only a very weak, memory trace is available in the lesioned hippocampus. It is concluded that the above results are due to the inability of the FD lesioned hippocampus to process the information received from the ipsilateral entorhinal cortex.

Animals↗
PubMed1997

Dissociation of exteroceptive and idiothetic orientation cues: effect on hippocampal place cells and place navigation.

Navigation by means of cognitive maps appears to require the hippocampus; hippocampal place cells (PCs) appear to store spatial memories because their discharge is confined to cell-specific places called firing fields (FFs). Experiments with rats manipulated idiothetic and landmark-related information to understand the relationship between PC activity and spatial cognition. Rotating a circular arena in the light caused a discrepancy between these cues. This discrepancy caused most FFs to disappear in both the arena and room reference frames. However, FFs persisted in the rotating arena frame when the discrepancy was reduced by darkness or by a card in the arena. The discrepancy was increased by 'field clamping' the rat in a room-defined FF location by rotations that countered its locomotion. Most FFs dissipated and reappeared an hour or more after the clamp. Place-avoidance experiments showed that navigation uses independent idiothetic and exteroceptive memories. Rats learned to avoid the unmarked footshock region within a circular arena. When acquired on the stable arena in the light, the location of the punishment was learned by using both room and idiothetic cues; extinction in the dark transferred to the following session in the light. If, however, extinction occurred during rotation, only the arena-frame avoidance was extinguished in darkness; the room-defined location was avoided when the lights were turned back on. Idiothetic memory of room-defined avoidance was not formed during rotation in light; regardless of rotation, there was no avoidance when the lights were turned off, but room-frame avoidance reappeared when the lights were turned back on. The place-preference task rewarded visits to an allocentric target location with a randomly dispersed pellet. The resulting behaviour alternated between random pellet searching and target-directed navigation, making it possible to examine PC correlates of these two classes of spatial behaviour. The independence of idiothetic and exteroceptive spatial memories and the disruption of PC firing during rotation suggest that PCs may not be necessary for spatial cognition; this idea can be tested by recordings during the place-avoidance and preference tasks.

Animals↗
PubMed1997

Overexpression of calcium-binding protein calgranulin B in colonic mucosal diseases.

Subtractive two-dimensional gel electrophoresis (2-DE) has been used for the study of the protein patterns of the normal colonic mucosa and the specimens collected from patients diagnosed for inflammatory bowel disease (IBD), colonic polyps and colorectal cancer. We found a 13 kDa protein that was detected in five of seven adenomas and in 13 of 15 colorectal carcinomas while it was absent or only slightly expressed in normal colonic mucosa. Furthermore, this protein occurred in all specimens collected from patients suffering from IBD and its quantity reflected the increased severity of inflammation. The combination of microsequencing and mass spectrometry led to the identification of the 13 kDa spot as calgranulin B. Our results indicate that the production of calgranulin B is unregulated in inflammatory, preneoplastic and neoplastic lesions of colonic mucosa.

Adult↗
PubMed1997

Severe spatial navigation deficit in the Morris water maze after single high dose of neonatal x-ray irradiation in the rat.

Ambiguous spatial behavior deficits induced in adult rats by different types of dentate gyrus lesions were examined by subjecting neonatal rats to x-ray irradiation, which reduces the granule cell population in fascia dentata without affecting the number of hilar neurons and pyramidal cells of Ammon's horn. Three- to six-month-old irradiated and intact male Long-Evans rats were tested in the Morris water maze. Four experiments were done. (i) Rats were trained to find an invisible escape platform, when started from any of four equidistant points at the circumference of the pool. (ii) The same rats then were trained to find a visible platform in the same pool. Poor performance of irradiated rats in both experiments suggested a visual deficit. (iii) Navigation in the absence of visual cues was studied in other rats trained in total darkness to find the escape platform under conditions of fixed start-fixed goal geometry. (iv) Contribution of nonvisual allocentric cues and egocentric path integration mechanisms to spatial performance of the above rats was tested in darkness after rotating both the start and goal positions by 90 degrees clockwise. Impairment of irradiated rats in Exp. 3 and 4 and histological examination of their brains support the conclusion that 60-70% reduction of granule cells in the dorsal hippocampus causes significant deterioration in both allocentric and egocentric orientation.

Analysis of Variance↗
PubMed1997

Place cells and place navigation.

The assumption that hippocampal place cells (PCs) form the neural substrate of cognitive maps can be experimentally tested by comparing the effect of experimental interventions on PC activity and place navigation. Conditions that interfere with place navigation (darkness, cholinergic blockade) but leave PC activity unaffected obviously disrupt spatial memory at a post-PC level. Situations creating a conflict between egocentric and allocentric orientation (place navigation in the Morris water maze filled with slowly rotating water) slow down spatial learning. PC recording in rats searching food pellets in a rotating arena makes it possible to determine which firing fields are stable relative to the room (allocentrically dependent on sighted extramaze landmarks), to the surface of the arena (dependent on egocentric path integration mechanisms and intra-arena cues), or disappear during rotation. Such comparison is made possible by the computerized tracking system simultaneously displaying a rat's locomotion and the respective firing rate maps both in the room reference and arena reference frames. More severe conflict between allocentric and egocentric inputs is produced in the field clamp situation when the rat searching food in a ring-shaped arena is always returned by rotation of the arena to the same allocentric position. Ten-minute exposure to this condition caused subsequent disintegration or remapping of 70% PCs (n = 100). Simultaneous examination of PC activity and navigation is possible in the place avoidance task. A rat searching food in a stationary or rotating arena learns to avoid an allocentrically or egocentrically defined location where it receives mild electric footshock. In the place preference task the rat releases pellet delivery by entering an unmarked goal area and staying in it for a criterion time. Both tasks allow direct comparison of the spatial reference frames used by the PCs and by the behaving animal.

Animals↗
PubMed1997

Retrieval of overtrained place navigation during occlusion of one eye and ipsi- or contralateral blockade of relevant brain centers in rats.

Place navigation engrams acquired with intact brain can be retrieved with either eye and are stored in both hemispheres. The retrieval circuitry was examined by testing an overtrained rat under lidocaine inactivation of the hippocampus, visual cortex, and superior colliculus. Thirty-three hooded rats with implanted cannulae aimed at the above structures were trained to find a target in the southwest quadrant of the pool. Retrieval was tested during occlusion of one eye alone or combined with ipsi- or contralateral blockade (1 microliter 4% lidocaine) of hippocampus, hippocampus and visual cortex, or hippocampus, visual cortex, and superior colliculus. The intact brain escape latencies (9.8 s) were only slightly prolonged by occlusion of one eye (to 12.6 s). Blockade of centers ipsi- or contralateral to the occluded eye increased escape latencies to 12.7 or 15.2 s for hippocampus, to 16.8 or 16.9 s for hippocampus and visual cortex, and to 23.6 or 17.4 s for hippocampus, visual cortex, and superior colliculus, respectively. Significant asymmetry appearing in the last case indicates that the superior colliculus plays an important role in mediation of the crossed visual input supporting place navigation. Residual goal-finding capability in rats with blockade of centers ipsilateral to the occluded eye is probably due to uncrossed visual projections to the intact hemisphere.

Animals↗
PubMed1997

Rotation of water in the Morris water maze interferes with path integration mechanisms of place navigation.

The idea that place navigation in the Morris water maze is implemented by path integration between locations determined by landmark sighting was investigated in a 200-cm-diameter pool in which circular (7.2 degrees/s) motion of water could be induced by tangentially arranged water jets. The rats were trained at 8 trials per day to navigate to an erectable platform which was raised after the rat had spent a criterion time in the target annulus (30 cm in diameter) in the midpoint of the NW quadrant. Asymptotic escape latency of 7 s was reached after 9 days in moving water (n = 8) and after 6 days in stationary water (n = 8). The group overtrained for 13 days in stable water performed well even after it was transferred to moving water. Changing the sense of rotation of water from counterclockwise to clockwise did not affect the asymptotic performance. The above findings show that overtrained rats rely on landmark sighting rather than on path integration. The influence of water movement reappeared when place navigation to a new target (SW) was examined in alternating 2-s periods of light (L) and darkness (D). On the first day, the latencies were 15.2 +/- 1.2 and 22.8 +/- 1.9 s in stable and moving water, respectively, but dropped to 10 s on the following day. The tracks generated in the L period were more tortuous than those generated in the D period and this difference was more pronounced in moving than in stable water. It is concluded that path integration mechanisms supporting navigation during intervals of darkness are impaired in moving water but that this impairment disappears in overtrained animals.

Animals↗