The role of the neoadjuvant therapy in the surgical treatment of localy advanced oesophageal cancer

8

Altered stimulus frequency and intensity dependence of the somatosensory evoked potential in rats after acute application of two mitochondrial toxins

Mitochondrial toxins are a special group of toxicants with nervous system ef TRACT - fects. The resulting nervous system damage could be detected and followed-up by means of functional biomarkers but these still have to be worked out. In this work, adult male Wistar rats were anesthetized with urethane, the left hemisphere was exposed, and a silver recording electrode was placed on the projection area of the whiskers. The whisker pad was stimulated with electric square pulses and the cortical response was recorded. The intensity of the stimulus was varied between 25% and 100% (just supramaximal), and its frequency, between 1 and 10 Hz. Control records were taken, then one of the agents (3-nitrporopionic acid, a mitochondrial toxin of microfungal origin: 20 mg/kg b.w.; or manganese, a heavy metal: 50 mg/kg b.w. in chloride form) was injected ip. and further records were taken. Both agents had an effect on the latency, but on the amplitude, only Mn. Of the relationships between stimulation settings and evoked potential parameters, frequency dependence of latency had the clearest alteration on application of Mn or 3-NP. Such effects may have the potency to be developed to functional biomarkers, applicable in practical toxicology or in animal research

Turning gold into 'junk': transposable elements utilize central proteins of cellular networks

The numerous discovered cases of domesticated transposable element (TE) proteins led to the recognition that TEs are a significant source of evolutionary innovation. However, much less is known about the reverse process, whether and to what degree the evolution of TEs is influenced by the genome of their hosts. We addressed this issue by searching for cases of incorporation of host genes into the sequence of TEs and examined the systems-level properties of these genes using the Saccharomyces cerevisiae and Drosophila melanogaster genomes. We identified 51 cases where the evolutionary scenario was the incorporation of a host gene fragment into a TE consensus sequence, and we show that both the yeast and fly homologues of the incorporated protein sequences have central positions in the cellular networks. An analysis of selective pressure (Ka/Ks ratio) detected significant selection in 37% of the cases. Recent research on retrovirus-host interactions shows that virus proteins preferentially target hubs of the host interaction networks enabling them to take over the host cell using only a few proteins. We propose that TEs face a similar evolutionary pressure to evolve proteins with high interacting capacities and take some of the necessary protein domains directly from their hosts

Investigation of effects of two environmental heavy metals in a combined exposure model on the nervous system in rats

In the present study, the interaction of inhalational and oral exposure to manganese and lead was investigated. Young adult male Wistar rats (2 x 10 per group) were treated orally with MnCl2 (15 and 60 mg/kg b.w.) or Pb acetate (80 and 320 mg/kg) for 3 or 6 weeks. Then, one half of the groups was further treated by intratracheal instillation of nanoparticulate MnO2 (2.63 mg/kg) or PbO (2 mg/kg) for an equal period of time. Body weight gain and signs of general toxicity were regularly checked. Finally, the rats’ motor behavior was tested in an open field box, and their spontaneous and evoked cortical electrical activity was recorded in urethane anesthesia. MnO2 nanoparticles caused disproportionately strong reduction of body weight gain but with Pb the weight effect was more dependent on dose. In the open field test, Mn caused hypomotility, more strongly after 6 weeks oral plus 6 weeks intratracheal than after 6 weeks oral treatment. Pb-treated rats showed increased ambulation but less rearing and somewhat longer local activity. Spontaneous cortical activity was shifted to higher frequencies after oral Mn application, but this change was not intensified by subsequent nanoparticle application. Oral Pb had an opposite effect. Cortical evoked potentials showed latency lengthening. In several cases, the effect of Mn and Pb was about as strong after 3 weeks oral plus 3 weeks intratracheal as after 6 weeks oral administration, although the summed dose was ca. two times lower in the former case. There can be a more-than-additive interaction between the amounts of heavy metals entering the organism in different routes and chemical forms

The effects of 3-nitropropionic acid on the behavior and cortical electrical activity of rats in acute administration

In this study, the acute effects of 3-nitropropionic acid was investigated on open field and startle behavior of rats, and on their cortical electrical activity. Spontaneous locomotor activity, acoustic startle response, and pre-pulse inhibition of acoustic startle were measured in male Wistar rats (10 weeks old, 180-200g body weight) after a single dose of 10 or 20 mg/kg i.p. 3-nitropropionic acid. After the behavioral tests, the rats were anaesthetized, and spontaneous cortical electrical activity was recorded. The vertical, horizontal and local open field performance showed dose-dependent deterioration in the rats treated with 3-nitropropionic acid. The number of “noise-positive” startle responses showed non-significant changes, but the inhibition by pre-pulse was significantly reduced in the high dose animals. High dose also increased the proportion of low-frequencies in the cortical activity. Three-nitropropionic acid, known primarily to act in repeated doses (e.g., in animal models of Huntington’s disease) had also some clear-cut acute effects on behavioral and electrophysiological parameters of the treated rats

Food Safety in the Public Awareness

National and international surveys show that people still do not have appropriate knowledge of and attitude to food safety. Therefore more and more countries organize educational courses to improve skills and knowledge regarding food safety. In Hungary the National Curriculum 2012 contains the program for food safety education. The aim of our survey was investigation about knowledge and attitude of primary and secondary school students towards food safety. The questions, according to international surveys, fell into 5 categories: personal hygiene, keeping food at safe temperatures, adequate cooking, avoidance of cross-contamination, and safe source of foods. Statistical evaluation was done using SPSS 20 software. Significant differences were evaluated by logistic regression, Chi square test, and crossing table analysis. Results showed that there was no significant difference among primary school students regarding gender or residence (village or town) in knowledge of food safety. Their attitudes showed more significant divergence. Logistic regression investigation has showed that there was a good correlation between knowledge and attitude of personal and kitchen hygiene. In conclusion, our students have presented more or less the same results as the others from international questionnaires. Even though, we need to improve knowledge and skill in food safety

Parallel changes of the spontaneous and stimulus-evoked cortical activity elicited by acute treatment with inorganic mercury in rats

Mercury is known to affect the activity of the nervous system of animals and humans, as indicated by the multitude of neurological signs following e.g. occupational exposure. In animal experiments, heavy metals cause a variety of alterations in the central and peripheral nervous system activity but an explanation as to mechanism of action is missing in a number of cases. The aim of the work presented was to find correlation between the changes of spontaneous cortical activity (electrocorticogram, ECoG) and cortical sensory evoked potentials (EPs) recorded from rats acutely treated with mercuric chloride. Adult male Wistar rats were anesthesized with urethane. Silver recording electrodes were placed on the exposed left somatosensory projection area of the whiskers and of the tail. The corresponding peripheral sites were stimulated by electric pulses. During tail stimulation, compound action potentials of the tail nerve were also recorded. After at least 4 control records, mercury (HgCl2, 7 mg/kg) was administered via a peritoneal cannula and the recording was continued for further ca. 2 hours. In the spontaneous activity, increased activity of the low and decreased activity of the high frequency bands was seen Simultaneously, the amplitude of the EPs increased. On the tail nerve potential, Hg caused an amplitude decrease and a latency increase. Latency increase of the cortical EP and the decrease of nerve conduction velocity evolved simultaneously. The alterations are likely due to some specific, and not to a general toxic, effect of Hg

Neurotoxicity of manganese analysed by a novel combined electrophysiological-behavioral recording system

A novel electrophysiological-behavioral recording system, developed by Experimetria Ltd., Hungary in cooperation with our Department, was used to study the effects of manganese, a neurotoxicant frequently causing human nervous system disease in occupational exposure. Male Wistar rats were equipped with a “crown” enabling the recording of electrocorticogram (ECoG) in awake, freely moving state. One 60-min recording session per week was held for 10 weeks, in which the rats’ movements in an open field (OF) box and their ECoG were simultaneously recorded. After the 2nd week, treated rats had 7.5 mg/1 MnCf in the drinking water (control: normal tapwater) and further 8 recordings were made. From the OF records, ambulation distance and the time spent with ambulation, local activity and immobility was obtained. From the ECoG, power spectrum and total power was calculated. In the first weeks of Mn exposure, the rats’ motility substantially decreased, and these changes showed little further progression. The decay of motility during one 60-min session was also stronger in exposed rats. The total power of ECoG increased in the first 4 weeks but the spectrum was hardly changed. The total power and spectrum of ECoG and the level of motility were apparently correlated, and the functional alterations showed some dependence on treatment time and/or summed dose. Combined, repeated ECoG and motility recording is suitable to follow-up the development of neurotoxicity induced by Mn, and possibly other environmental neurotoxicants