Biomedical subjects

J Bures

Publications and source records attributed to J Bures.

At least 127 records · Page 7Linked to original sources

PubMed1991

[Colicinogeny in nonspecific intestinal inflammations and colorectal cancer].

Colicins are proteinaceous substances produced by Escherichia coli strains and related bacteria of Enterobacteriaceae family. They are considered to be an important factor in preserving the balance of the intestinal microflora. Their antibiotic action on susceptible bacteria is supplemented with cytotoxicity for several pro- and eukaryotic cells. The large bowel is a natural site of their action. Besides of enhancing oxidoreductive activity of leukocytes in vitro, colicins are also believed to influence inflammatory reaction in vivo. For these reasons, the first part of the present work was concerned with studying colicinogeny in nonspecific inflammatory bowel diseases (IBD). No significant difference has been found out in colicinogeny between a total of 93 IBD-related and 160 healthy controls. In testing leukocyte migration inhibition, colicins of autologous E. coli were used as antigens. The migration index out of normal range showed 36% patients with ulcerative colitis (5/14), 80% patients with Crohn's disease (12/15), and only one clinically healthy control subject (1/16; 6%). The obtained results are considered to be proof of cellular hypersensitivity of IBD patients to colicins of their own E. coli strains. In several colicins the antitumorous effect has been reported in both the in vitro and in vivo experimentation. The second part of this work was concerned with colicinogeny in colorectal cancer. Colicinogenic E. coli were evidenced in 42 subjects (40%) from 105 patients with colorectal carcinoma. Controls showed colicinogenic E. coli in 102/160 clinically healthy subjects (64%), and the difference was as significant as p less than 0.05. In colorectal cancer group, the subjects with proved colicinogeny showed lesser amounts of colicinogenic E. coli strains in contrast with non-colicinogenic ones. In colorectal cancer patients with colicinogenic E. coli strains, B and M colicins were of most frequent occurrence in them no antitumorous effect has been experimentally stated. If changes of colicinogeny were only either the manifestation or consequence of tumor disease, so both the presence or absence of colicinogenic E. coli would have been dependent of clinical patients's condition, stage of disease (in accord with Dukes) or correlated with the tumor markers. For these accounts, a total of 28 colorectal cancer patients underwent a colicinogenic study. However, no colicinogeny dependence was evidenced of either clinical condition or Dukes stage, showing no correlation with any of cancer markers investigated (carcinoembryonic antigen, CA 19-9, alfa-1-fetoprotein, alfa-1-orosomucoid, Cancer serum index, sialic acid, lysozyme).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1991

[Plasmapheresis in the treatment of Crohn's disease].

Crohn's disease is a disease with unknown etiology of which immunological mechanisms participate. As standard treatment is sometimes ineffective, in 15 patients therapeutic plasmapheresis was used. Before plasmapheresis and immediately after it some immunological parameters were assessed. In the serum a significant drop of all immunoglobulins of the basic classes was recorded: (P less than 0.05) and of circulating immunocomplexes (P less than 0.02). Marked clinical improvement was observed in three patients, which as compared with data in the literature, is somewhat less. The cause is in the author's opinion in the selection of patients (plasmapheresis is usually most successful in patients with marked activity of the disease and non-intestinal symptoms) even in case of less active plasma exchange. Despite this plasmapheresis can be recommended in patients with a poor response to common conservative treatment and in some of them we may expect a marked therapeutic effect with a favourable influence on the prognosis of the disease.

Adolescent↗

PubMed1990

[Excretion of phenol and p-cresol in the urine in fasting obese individuals and in persons treated with total enteral nutrition].

In the literature it is maintained that phenol and p-cresol are produced in humans in the gut by bacteria from dietary protein. Both substances are absorbed from the small intestine and excreted in the urine. If the urinary output of phenol and p-cresol depends really on the dietary protein intake it should decline to zero values during fasting and correlate with the protein supply into the gut. The objective of the present work was therefore to investigate the urinary phenol and p-cresol excretion in fasting obese subjects (21 fasting subjects, 7 subjects with modified fasts--Nutramine R-350) and in subjects treated by complete enteral nutrition by a nasojejunal tube (8 patients with Crohn's disease, 8 with another disease of the gastrointestinal tract). Phenol and p-cresol in 24-hour urine specimens were assessed by gas chromatography in all four groups always on the 1st, 7th and 14th day. In fasting obese subjects the phenol and p-cresol values did not decline (the difference of values from the assumed zero value is significant z = 0.000055). There was no difference between patients with a complete and modified fast. The phenol and p-cresol values did not correlate mutually, nor with the protein intake, nitrogen balance and cumulated nitrogen balance. There are great individual differences in the urinary phenol and p-cresol excretion and it does not depend on the oral dietary protein intake, as hitherto assumed. It has most probably more complex causes and the decisive factor seems to be the metabolic activity of the intestinal bacterial microflora.

Adult↗

PubMed1990

Differential control of operant and consummatory licking in rats.

The failure of rats to optimize their behavior when drinking from two retractable spouts available for single licks was analyzed. The rats were trained in an apparatus where the contacted spout was withdrawn after completion of a lick and the other spout was presented. After 5 days of such forced spout alternation training the animals continued to emit 2.7 instead of the optimum 1.0 lick per spout presentation (LPSP). With water available in one spout only the average LPSP at the empty spout dropped to 1.2 and increased to 3.6 at the water containing spout. It is argued that the operant licks at the dry spout approach the ideal value of 1.0 LPSP whereas the number of LPSPs at the water spout is increased by the consummatory nature of licking triggered by the presence of water in the oral cavity.

Animals↗

PubMed1990

Ketamine blockade of spreading depression: rapid development of tolerance.

Persistence of the ketamine-induced blockade of spreading depression (SD) was studied in 15 rats, anesthetized with 200 mg/kg ketamine followed at 50- to 60-min intervals by 3-5 injections of 100 mg/kg of the drug. Cortical or caudate SDs evoked 10 min after the first ketamine injection were blocked but the amplitude of SD waves elicited at regular 10-min intervals gradually increased while the blockade induced by subsequent ketamine injections weakened and became unrecognizable after the fifth injection. The result was not due to prolonged action of ketamine alone but rather to combined effect of ketamine and SD repetition. The development of tolerance is probably due to use-dependence of NMDA-gated channels which must be taken into account when assessing the therapeutic value of NMDA antagonists in treatment of brain ischemia.

Acetates↗

PubMed1990

[Urinary excretion of phenol in Crohn disease during total parenteral nutrition].

Urinary phenol is a product of dietary tyrosine metabolism generated in the gut by bacteria. In our previous study we found in 42 patients with Crohn's disease a significantly higher level of urinary phenol in terminal ileitis and ileal resection when compared with Crohn's segmental colitis. Urinary phenol is believed to be extensively influenced by diet. For this purpose our present paper investigated urinary phenol in Crohn's disease before and after two weeks of total parenteral nutrition. Spectrophotometric analysis of urinary phenol was carried out in 10 patients (7 males, 3 females). They ranged from 24 to 40 (average 34.9) years of age. The patients received on an average 1.45 g of amino acids/kg/day (no tyrosine; 0.022 g of L-phenyl-alanine/kg/day), 25-30 kcal/kg/day (105-125 kJ/kg/day) in non-protein sources of energy, and fat-emulsions (80 g/day) twice a week. There was a significant decrease in the urinary phenol after two weeks of total parenteral nutrition (median 79.5, interquartile range 41.5 to 288.5 mumols/24 hours vs. median 37.5, interquartile range 0-93.5 mumols/24 hours), p = 0.032 using the paired t-test. In two patients with severe involvement of the gut, urinary phenol, though decreased, remained at higher levels (above 300 mumols/24 hours). A significant decrease of the urinary phenol can be explained in particular by exclusion of dietary proteins, although clinical and nutritional improvement was observed, too. However, persisting higher levels of urinary phenol in some patients with serious involvement of the gut may reflect the severity of Crohn's disease.

Adult↗

PubMed1990

The reaching reaction in the rat: a part of the digging pattern?

The relationship between acquired lateralized reaching and analogous innate movement patterns was examined in adult rats. In Expt. I, 8 naive rats were trained to reach into a narrow trough-shaped feeder. Analysis of the videorecorded movement showed that the forelimb extension starts 120 ms before the forepaw enters the feeder, lasts 190 ms and can be repeated at 280-ms intervals. Before reaching, the rat assumes a stereotyped posture and inserts its nose into the feeder entrance. Twelve rats used in Expt. II were raised from weaning with limited opportunity to practice manipulative skills. Six of these animals were then trained as in Expt. I. In spite of the lack of experience, they learned the reaching task as efficiently as normal rats. The remaining 6 rats were offered food placed into a wide tunnel-shaped feeder. The animals did not take advantage of the possibility of using both forelimbs, but developed typical lateralized reaching. In Expt. III, 4 rats were trained to retrieve food pellets buried under a layer of sand. The videorecorded digging movement essentially resembled reaching but the two forepaws alternated, the extension amplitude was shorter and the movement was never terminated by grasping. It is concluded that the lateralized reaching develops from modified digging and that the kinship of the two movements accounts for the stereotypy and limited modifiability of the acquired reaction.

Animals↗

PubMed1990

Acquisition of conditioned taste aversion in rats is prevented by tetrodotoxin blockade of a small midbrain region centered around the parabrachial nuclei.

A remarkable feature of conditioned taste aversion (CTA) is the resistance of the association between the gustatory trace and symptoms of poisoning against disruptive procedures. In an attempt to identify the neural substrate of this phase of CTA acquisition, thirsty rats were offered 0.1% saccharin for 15 min, were immediately afterwards anesthetized with pentobarbital, received stereotaxic injections of tetrodotoxin (TTX, 10 ng/microliters) into various brainstem regions and were poisoned with IP injection of LiCl (0.15 M, 2% body weight). In Experiment 1, TTX prevented CTA acquisition when injected into the parabrachial nuclei but was ineffective in the lower medulla. TTX alone did not elicit CTA even at brain sites in which it caused death in 30% of the animals. In Experiment 2, the brainstem was systematically explored by a grid of bilateral TTX injections. A spatial gradient of the CTA disruption pointed to the parabrachial nuclei as the brain region responsible for the amnesic effect observed. Experiment 3 showed that a single TTX injection into the parabrachial nucleus on one side did not prevent CTA acquisition and that similarly ineffective were TTX injections in the sagittal plane both at the mesencephalic and bulbar levels. It is concluded that the pivotal role of the parabrachial nuclei in the formation of the permanent CTA engram can only be revealed by functional blockade which is more radical than that achieved during general anesthesia.

Animals↗

PubMed1990

Differential effect of ketamine on the reference and working memory versions of the Morris water maze task.

The assumption that blockade of long-term potentiation by N-methyl-D-aspartate antagonists interferes with spatial memory was supported by experiments showing that 15 mg/kg ketamine impairs acquisition of navigation to a hidden platform but not to a visible platform. Higher doses were required to impair retrieval of overtrained place navigation. In a working memory version of the task, retrieval latencies were shorter than acquisition latencies with 4- to 15-min but not with 30- and 60-min delays. Latent learning was only effective with the 4-min delay. Ketamine prolonged the initial search of the hidden platform at 3 mg/kg and impaired latent learning but not active acquisition at 1.5-10 mg/kg. Comparison of behavioral and synaptic effects of ketamine suggests that long-term potentiation is a necessary condition, but not a sufficient condition, for acquisition of place navigation, because search strategy and latent place learning are impaired by ketamine doses not interfering with this synaptic phenomenon.

Animals↗

PubMed1990

Unilateral striatal grafts induce behavioral and electrophysiological asymmetry in rats with bilateral kainate lesions of the caudate nucleus.

Rats (n = 11) with bilateral kainate lesions of the caudate nucleus and subsequent unilateral transplantation of embryonic striatal tissue into the damaged area preferred 4 months later to reach for food with the forepaw contralateral to the graft. No such asymmetry was observed in lesioned, nontransplanted (n = 8) or unoperated (n = 5) control rats. Good integration of the graft with the host brain was indicated by the finding that cortical spreading depression did not enter the lesioned caudate nucleus but did penetrate into the lesioned caudate with the graft almost as regularly as in intact rats. Behavioral asymmetry produced by unilateral grafts in bilaterally lesioned animals reveals the effects of transplantation with more sensitivity than the graft-induced compensation of the asymmetries caused by unilateral lesions.

Animals↗

PubMed1990

Conditioned taste aversion is disrupted by prolonged retrograde effects of intracerebral injection of tetrodotoxin in rats.

Acquisition of conditioned taste aversion (CTA) is disrupted when 10 ng tetrodotoxin (TTX) is injected into both parabrachial nuclei of rats immediately after saccharin drinking and before LiCl poisoning (Ivanova & Bures, in press). Further analysis of this finding showed that parabrachial TTX injection (a) elicited retrograde amnesia also when applied 1, 2, or 4 days but not 8 days after CTA acquisition; (b) did not abolish CTA produced by 2 or 3 saccharin-LiCl pairings; (c) did not cause persistent increase of quinine threshold; and (d) elicited anterograde CTA amnesia when applied 1 but not 2, 4, or 8 days before CTA acquisition. TTX-induced amnesia is not due to persistent gustatory agnosia but rather to disruption of the protracted consolidation of the permanent CTA engram by prolonged cessation of impulse activity in the information storing network.

Animals↗

PubMed1990

Importance of determining lysozyme in colorectal cancer.

In the last few years, an increase in the incidence of malignant tumours of the large bowel and the rectum has been observed in all advanced countries. Intensive search is therefore going on for biochemical and immunochemical markers which would help early diagnosis and monitoring of this disease. The most frequently used markers in colorectal cancer are CEA, CSi, CRP, CA 19-9 and sialic acid. The present study points out the possibility and advantage of using lysozyme determination in serum as another marker in patients with colorectal cancer.

Aged↗

PubMed1990

Specific cellular immune response in patients with Helicobacter pylori infection.

The leukocyte migration inhibition test was performed in 39 patients with Helicobacter pylori infection and in 38 patients without such infection. The culture of Helicobacter pylori was used as antigen. A highly significant inhibitory effect on leukocyte migration was found in patients with Helicobacter pylori infection. The results can be taken as proof of a systemic immune response to helicobacters at the cellular level in patients with Helicobacter pylori infection.

Adult↗

PubMed1990

[Campylobacter pylori, its detection and association with common pathologic conditions of the gastro-duodenum].

The authors evaluate clinical experience based on a correlation between the clinical condition and the finding of Campylobacter pylori (CP) in a total of 1027 specimens of the gastric mucosa. They confirmed the high incidence of CP in patients with a fresh duodenal ulcer (g 7%) but also in the inactive stage of duodenal ulcer disease (97.8%) and in patients with a pyloric ulcer (94.4%). An analogous incidence of CP in patients with so-called isolated duodenitis (in the course of the disease no ulcer lesion was ever detected), i.e. in 95.5%, indicates the relationship of this condition with peptic ulcer disease. The authors indicate diagnostic possibilities as regards CP infection by cultivation, rapid urease tests and microscopic examination and they emphasize the practical value of urease tests. Based on their own experience the authors confirm the high eradication effect of bismuth preparations, in particular bismuth subsalicylate and colloid bismuth subcitrate.

Campylobacter↗

PubMed1989

[Enteral nutrition in clinical practice. Pathophysiologic basis of the effective use of enteral nutrition].

Enteral nutrition by means of a thin tube is a significant enrichment of methods of nutritional support of patients in a catabolic state and those suffering from malnutrition. For the rational use of this method it is important to have reliable knowledge of physiological and pathophysiological processes in the course of digestion and absorption of nutrients, metabolism of energy substrates and to know the technique of enteral nutrition. The submitted brief review provides basic information on the problem.

Dietary Carbohydrates↗

PubMed1989

Conditioned taste aversion to injected flavor: differential effect of anesthesia on the formation of the gustatory trace and on its association with poisoning in rats.

Anesthesia disrupts formation of conditioned taste aversion (CTA) when induced before presentation of the gustatory stimulus but does not prevent association of the already formed gustatory trace with delayed poisoning. The transition between the disruption-prone and disruption-resistant phases of CTA acquisition was examined under conditions eliminating the confounding effect of anesthesia on ingestive behavior. Intraperitoneal injection of 2% saccharin (1% b.wt.) was used as an intravascular gustatory conditioned stimulus (CS) followed 2 h later by the visceral unconditioned stimulus (US) (LiCl 0.15 mol/l, 2% b.wt.). Pentobarbital anesthesia (50 mg/kg) prevented CTA formation when applied 4 h before to 30 min after saccharin injection, but was ineffective in the second half of the CS-US interval (1-2 h after saccharin administration). CTA acquisition was also impaired by subanesthetic dosages of pentobarbital (10 and 20 mg/kg) preceding i.p. injection of saccharin. It is concluded that the abrupt disappearance of the disruptive effect of pentobarbital in the middle of the CS-US interval marks the formation of the gustatory trace which mediates CTA learning even when both CS and US are applied by i.p. injection.

Anesthesia↗

PubMed1989

The effect of embryonal amygdala grafts on the impairment of spatial working memory elicited in rats by kainate-induced amygdaloid damage.

The effect of epileptogenic lesion of amygdala on spatial working memory was examined in rats after unilateral (U, n = 9) or bilateral (B, n = 8) injection of 1 or 0.5 mu of 0.2% kainate into the amygdaloid complex. Another group of unilaterally lesioned rats (T, n = 9) received 8 days after kainate injection grafts of embryonal (E 20) amygdala into the damaged region. Twelve days after lesion the three experimental groups and an unoperated control group (C, n = 11) were trained during three weeks in the aversively motivated 8-arm radial water maze (RWM). Training decreased incidence of errors/8 choices from the initial 2.3 to 1.2 in the lesioned rats and to 0.4 in the controls. Transplantation did not enhance RWM acquisition but restored the symmetrical pattern of choices and normalized the emotionality of lesioned animals. Retraining the RWM task 3 months later revealed significant savings in the control group but not in the transplanted group. Histology showed in addition to large lesion at the injection site also distant lesions in the ipsilateral hippocampus, thalamus and neocortex and in the unilaterally injected rats also in the contralateral amygdala. Healthy, well integrated transplants found in 6 out of 9 transplanted rats reduced the incidence of remote lesions (particularly in the contralateral hemisphere). Performance of individual animals reflected the state of the transplant. It is concluded that the impairment of spatial working memory is due not only to destruction of amygdala but also to diffuse damage of the limbic system. The slowly developing seizure-induced distant lesions can be partly prevented by embryonal grafts.

Amygdala↗

PubMed1989

Vestibular stimulation disrupts acquisition of place navigation in the Morris water tank task.

The significance of vestibular input for place navigation in the Morris water maze was examined in 11 hooded rats. A 5-min rotation (2 Hz) immediately preceding retrieval of an overtrained place navigation task prolonged escape latencies by about 10 s corresponding to circular swimming induced by postrotatory aftereffects, but did not otherwise interfere with target location. A 1-min rotation immediately following the acquisition trial in the working memory version of the water maze task did not deteriorate performance in the retrieval trial performed 5 min later. Two components of the acquisition trial, i.e., active search of the hidden target (up to 1 min) and latent learning during the 30-s stay on the platform, contribute almost equally to the formation of the working memory trace. A 1-min rotation immediately preceding the isolated platform learning component impaired subsequent retrieval but was ineffective when applied 3 min earlier. Latent learning was completely disrupted when the platform with the animal was rotated during the entire 30-s stay on the target platform or when the 30-s stay on the stationary platform was followed 0 or 3 min later by a 30-s rotation on the platform. The interfering effect of the latter procedure was suppressed by covering the platform with the animal by an opaque cylinder. It is concluded that vestibular cues are particularly important for the orientation of the animal in the gravitation field and for the estimation of the angles between vectors plotted from the animal toward external landmarks. Agreement between vestibular and visual signals is a prerequisite of efficient navigation.

Animals↗