Problem-oriented teaching of molecular cell biology.
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Education, Medical, Undergraduate↗
Biomedical subjects
A Tigyi
Publications and source records attributed to A Tigyi.
Influence of 3-methylcholanthrene on the redox-state of liver and red muscles in vivo.
It was observed, that following an injection of 3-methylcholanthrene (MC), the tissue redox-state potential is modified expressively both in liver and in red muscles. In the liver in the first day an oxidosis develops, which is followed by redosis, but in the muscle a redosis can be observed already in the first day. It is a meaningful fact, that MC influences biochemical processes in the early phase of its effect not only in the liver but also in the red muscle. By reason of this data the possibility of a prevention of the MC influence by adequate redox agents might also be arised.
Animals↗
Opposite effects of methylene blue and ascorbate on lipid peroxidation in muscles. Correlation with the redox state. I. Experiments on satisfied frogs.
Homogenates of heart, stomach and rectus abdominis muscles of the frog have shown different degrees of malondialdehyde (MDA) formation. MDA content was highest in heart, and lowest in stomach musculature. The resultant tissue redox-state potential (RSP) and redox potential (E'0) in homogenates determined potentiometrically also showed differences with opposite signs in relation to MDA levels. An electron acceptor, methylene blue (MB), decreased but an electron donor, ascorbate (Asc), increased the MDA level in each of the muscles. These effects were dependent upon the concentration of MB and Asc and proportional to the control MDA content in each muscle. Thus an inverse interdependence between MDA level and redox state existed even when a positive change in redox potentials was induced by MB, and also when a negative change was induced by Asc. Since there was a close negative correlation between the changes of MDA concentration and redox potential in the homogenates, it is strongly suggested that the changes of redox state in muscle are implicated in the processes leading to lipid peroxidation (LP).
Animals↗
The free radical mechanisms in beta-carotene induced gastric cytoprotection in HCl model.
The aims of our experiments were to clear up the possible correlations between the free radical mechanisms and the gastric cytoprotection of beta-carotene on HCl-induced gastric mucosal lesions. The beta-carotene was intragastrically given in doses of 1 and 10 mg/kg and 30 min. later 1 ml 0.6 N HCl was given to provoke the mucosal damage. After 1, 5, 15, 30 and 60 min. the animals were sacrificed. The number and severity of gastric mucosal lesions were calculated. The superoxide dismutase (SOD), glutathion peroxidase (GPX), catalase (CAT) activity and the malondialdehyde (MDA) and reduced glutathion (GSH) contents were determined from the gastric mucosa of rats. It was found that 1. beta-carotene was able to reduce the number and severity of ulcers only after 30 min.; 2. the CAT activity was decreased at 60 min. by carotene; 3. the GPX activity became dissimilar in the different groups after 15 min; 4. the changes of GSH were found to be similar ones; 5. the SOD activity was lower during the cyto-protection; 6. the MDA level remained practically unchanged. It has been concluded that 1. the free radicals are the consequences of the development of gastric ulcer and cytoprotection; 2. the scavenger character of beta-carotene is involved in its cytoprotective effect.
Animals↗
A unique cell type in the lung--the Clara cell (the non-ciliated bronchiolar epithelial cell).
The non-ciliated bronchiolar epithelial cells (the Clara cells) are found most frequently in the distal conducting airways, but they are found throughout the tracheobronchial tree of different mammalian species. According to recent data, the main functions of the Clara cells can summarized as (1), the secretion of certain components of the extracellular bronchiolar lining layer (2), metabolism and detoxification of xenobiotics and other toxic compound (3) and participation in the renewal process of the bronchiolar epithelium. The main goal of this paper is to collect and discuss some of the general features of Clara cells from a functional-morphological point of view, and their possible role in pathological alterations of the lung especially in the pathogenesis of lung tumours originated from Clara cells.
Animals↗
The use of application test, a novel type of problem-solving exercise as a tool of teaching and assessment of competence in medical biology.
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Competency-Based Education↗
Lipid peroxidation in lung of rats exposed to hyperoxic, hypoxic and ischemic effects.
Rat experiments were undertaken to describe the range of the endogenous lipid peroxidation (measured by formation of malondialdehyde [MDA] in lung tissue) and to analyze the effects of hyperoxic, hypoxic and ischemic influences. The acute hyperoxia caused a moderate increase in lipid peroxidation. The MDA formation in lungs of rats was perceptibly higher in low oxygen environment, while the highest values were found in ischemic lungs. The cytotoxic metabolites cause unfavourable influences on the lung structure (perivascular, interstitial and alveolar edema, destroyed epithelial lining with disintegration of lamellar membranes of the type II-pneumocytes). The findings suggest that potential danger of the oxygen free radicals is an increased lipid peroxidation of lung tissue causing alveolocapillary destruction and extensive exudation with pathologic dwindling of lung function.
Animals↗
Nucleolar activity after 3-methylcholanthrene treatment of rat liver cells studied by silver staining procedure.
The influence of a single dose of 3-methylcholanthrene (3-MC) was studied in nucleoli of young rat liver cells by means of conventional and ultracytochemical methods. The nucleolar activity was stimulated in our experimental conditions: the appearance of the fibrillar centres in the liver cell nucleoli as well as the silver staining protein content of the fibrillar centres and the dense fibrillar component were increased by 3-MC. The results suggest that the activity of ribosomal genes was increased following 3-MC treatment.
Animals↗
Comparison of heterogeneous nuclear ribonucleoprotein particles of the developing rat liver.
hnRNP monoparticles were isolated from livers of newborn (1 day), 7, 10, 11, 14, 21, 28 days old and adult rats, and their sedimentation properties, buoyant densities and protein composition were compared. There were observable differences neither in sedimentation nor in buoyant density among the particles isolated from livers of rats of different ages. The hnRNP particles derived from every stage of ages sedimented in the 30-50S zone of sucrose gradient with a peak at about 38S. Glutaraldehyde fixed particles in CsCl gradients banded at 1.36 g/cm3 which corresponds to about 80% of protein in the particles. Urea/sodium dodecyl sulfate/polyacrylamide gel electrophoresis of hnRNP proteins demonstrated 19 polypeptides in the 35,000-140,000 Mr range. Three main polypeptides in hnRNP of every group of animals could be observed with apparent Mr of 39,000, 43,000 and 46,000. In the minor components only quantitative differences could be seen in the different age groups with the exception of a 35,000-Mr polypeptide which appeared on the 11th day after the birth.
Animals↗
Effect of 3-methylcholanthrene on the protein composition of heterogeneous nuclear ribonucleoprotein particles in developing rat liver.
Nine-day-old rats were treated with a single 100 mg/kg body weight intraperitoneal dose of 3-methylcholanthrene (3-MC). 24, 48, 72 and 120 h later the protein composition of the heterogeneous nuclear ribonucleoprotein particles derived from the liver was analysed. The analysis was performed by urea-sodium dodecyl sulphate polyacrylamide gel electrophoresis. The protein composition of the hnRNP particles was compared to that derived from control animals of similar ages. The 35 000-Mr polypeptide which is normally absent found in the hnRNP particles of the young rats prior to the 11th day of life appears on the 10th day after 24 h 3-MC exposition. In addition, the minor polypeptide components of the particles were also found in higher quantity. The polypeptide pattern of the hnRNP particles derived from treated animals resembled those of the older animals but not those of controls of similar ages. Thus, the apparent accelerating effect of 3-MC on the liver development is also valid at the level of hnRNP particles.
Animals↗
The interrelationships between the lipid peroxidation, superoxide dismutase activity, development of gastric H+ secretion and gastric mucosal damage produced by intragastric administration of aspirin in pylorus-ligated rats.
Gastric mucosal damage of pylorus-ligated rats was induced by the intragastric administration of aspirin at 200 mg/kg at the time of ligation. The animals were sacrificed at 0, 1, 2, 3, and 4 h after the treatment. The gastric lesions (ulcers) were counted and their severities were calculated, and the volume of gastric secretion and the H+ output were measured. The extent of lipid peroxidation was assessed by measuring the malondialdehyde (MDA) in the gastric mucosa, simultaneously with measurement of the activity of superoxide dismutase (SOD). It was found in these pylorus-ligated rats that: the number of visible gastric lesions was significantly higher 1 h after aspirin administration than at other times; the severity of gastric lesions increased significantly at the 3rd and 4th hour after administration of aspirin; the volume of gastric secretory responses increased gradually after administration of aspirin and to a higher extent than the H+ output; the H+ output was significantly less after aspirin administration than that after pylorus ligation only; the gastric mucosal SOD activity significantly increased 1 h after administration of aspirin, decreasing significantly and gradually thereafter; the tissue level of MDA remained unchanged 1 h after aspirin administration, decreasing significantly thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
[Hypertrophy of type II pneumocytes in rats following exposure to DQ-12].
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Animals↗
Interrelationships between the development of the gastric cytoprotective effects of prostacyclin, atropine, cimetidine and the gastric mucosal superoxide dismutase activity in rats.
Gastric mucosal damage was produced by the intragastric administration of 96% ethanol or 0.6 M HCl. The cytoprotective doses of prostacyclin (PGI2) (5 micrograms/kg), atropine (0.025 mg/kg) or cimetidine (2.5 mg/kg) were given intraperitoneally 30 min before the administration of the necrotizing agents. The animals were killed 1 hr later. The number and severity of gastric mucosal lesions (ulcer) were recorded. At the time of the sacrifice of the animals, superoxide dismutase (SOD) was prepared from the gastric fundic mucosa and its activity was measured. It was found that PGI2 (5 micrograms/kg), atropine (0.025 mg/kg) and cimetidine (2.5 mg/kg) significantly decreased the number and severity of gastric mucosal lesions (ulcers) produced by the intragastric administration of 96% ethanol a 0.6 M HCl, PGI2, atropine, cimetidine, given in cytoprotective doses, significantly mounted the ethanol-induced increase of gastric mucosal SOD activity; PGI2, atropine, cimetidine, given them in cytoprotective doses significantly shunted the HCl-induced decrease of gastric mucosal SOD activity. It has been concluded that; chemically different cytoprotective agents (PGI2, atropine, cimetidine) give rise to similar tendencies in the changes of gastric mucosal SOD activity; both the significant decrease (in the ethanol-model) and the significant increase (in the HCl-model) of this enzyme seem to be involved in the development of gastric mucosal protection by PGI2, atropine and cimetidine.
Animals↗
Membrane perturbations in myocardium: oxygen radicals mediate injuries in experiments.
Experiments were undertaken on rats and dogs to study the range of endogenous lipid peroxidation (measured by formation of malondialdehyde in heart tissue) and to analyse the effects of hyperoxic, hypoxic and ischaemic influences. The acute hyperoxia caused a moderate increase in lipid peroxidation. The malondialdehyde formation was perceptibly higher in hypoxia, while the highest values were found in ischaemic hearts. It can be concluded that the cytotoxic oxygen metabolites cause unfavourable influences on heart structure and function, for this reason an antioxidant therapy is to be recommended.
Animals↗
The interrelationships between the development of ethanol-, HCl, NaOH and NaCl-induced gastric mucosal damage and the gastric mucosal superoxide dismutase activity in the rats.
Gastric mucosal damage was produced by intragastric administration of 96% ethanol, 0.6 M HCl, 0.2 M NaOH or 25% NaCl. The animals were killed 1 hr later, when the number and severity of gastric lesions (ulcers) was recorded. At the time of the sacrifice of the animals gastric mucosal superoxide dismutase (SOD) activity was measured. It was found that (1) the gastric mucosal damage could be induced by the administration of any of the necrotizing agents in all animals, (2) superoxide dismutase (SOD) activity increased significantly in the damaged gastric mucosa following 96% ethanol, while its activity decreased significantly during the development of gastric mucosal damage produced by the intragastric administration of 0.6 M HCl, 0.2 M NaOH or 25% NaCl. It has been concluded that: (1) the enzyme systems necessary to generate the superoxide free radical anions can be stimulated by ethanol, and they can be inhibited by the application of 0.6 M HCl, 0.2 M NaOH and 25% NaCl: (2) the observed stimulation or inhibition of the enzyme systems to generate the superoxide free radical anions may be of pathological significance in the development of gastric mucosal damage produced by the intragastric administration of 96% ethanol, 0.6 M HCl, 0.2 M. NaOH or 25% NaCl.
Animals↗
Interrelationships between the gastric cytoprotective effects of vitamin A and beta-carotene and the gastric mucosal superoxide dismutase activity in rats.
Gastric mucosal damage was produced in rats by the intragastric administration of 96% ethanol or 0.6 M HCl, according to the method of Robert et al. Vitamin A or beta-carotene, in doses of 10 mg/kg, given intragastrically 30 min before the administration of the necrotizing agents. The animals were killed 1 hr after the administration of the necrotizing agents. The following experimental parameters were studied, without and with application of vitamin A and beta-carotene; number of gastric lesions (ulcers); severity of gastric mucosal lesions (ulcers); gastric mucosal superoxide dismutase (SOD) activity. It was found that; vitamin A and beta-carotene, in doses of 10 mg/kg, are able to prevent significantly both the number and severity of gastric mucosal lesions (ulcers) produced by the application of 96% ethanol or 0.6 M HCl; the significant increase of ethanol-induced gastric mucosal SOD activity can be inhibited by the application of vitamin A and beta-carotene; vitamin A and beta-carotene are capable of preventing the development of gastric mucosal lesions (ulcers) produced by the intragastric administration of 0.6 M HCl, while these agents fail to compensate for the HCl-induced decrease of gastric mucosal SOD activity. It has been suggested that; vitamin A and beta-carotene are gastric cytoprotective agents; the ulcer preventive effects of vitamin A and beta-carotene are partly dependent on their scavanger behaviour.
Animals↗
Structural characterization of nuclear poly(A)-protein particles in rat liver.
Poly(A)-protein particles were prepared from rat liver nuclear extract after digestion with pancreatic ribonuclease and ribonuclease T1 by sucrose gradient centrifugation. The particles were sedimented in a range of 9-23S with a peak at 16S. The particles isolated in this manner were 99-100% resistant to further pancreatic ribonuclease treatment and contained more than 90% adenylic acid. In CsCl density gradient the nuclear poly(A)-protein particles banded in a narrow density range of 1.28-1.32 g/cm3 with a peak at 1.30 g/cm3, which corresponds to about 90% of protein in the particles. The average length of the poly(A) molecules prepared from the 16-S particles was about 140 nucleotides. Urea/sodium dodecyl sulphate/polyacrylamide gel electrophoresis demonstrated two major polypeptide components with Mr of 63 000 and 90 000 and at least ten minor polypeptides in the 45 000-130 000-Mr range. In sodium dodecyl sulphate/polyacrylamide gels the 63 000-Mr polypeptide was the only one major component. Amino acid analysis of the polypeptides bound to nuclear poly(A) revealed that the polypeptides contained a relatively large amount of aspartic acid + asparagine and glutamic acid + glutamine (24%). Treatment of glutaraldehyde-fixed particles with micrococcal nuclease showed that more than 90% of the poly(A) was accessible to the enzyme, thus almost the entire poly(A) should be located on the surface of the particles. On the basis of the results a model for the 'average' 16-S particle was constructed.
Animals↗
Lipid peroxidation in the membrane damaging effect of silica-containing dust on rat lungs.
Rats were injected intratracheally with a single dose of 50 mg silica (DQ-12) suspended in 0.5 ml saline. The animals were sacrificed at 3, 6, 12 and 21 days following exposure, and the rate of lipid peroxidation as well as the activities of superoxide dismutase and catalase were measured in the lung tissue. Parallelly the redox state potential of the lung tissues was also determined during this period. It was found that under the effect of silica, lipid peroxidation gradually increased in the lung. This effect was accompanied by enhancement of superoxide dismutase and catalase activity. The redox state potentials were shifted to oxidation. It is suggested that silica, though indirectly, induces free radical production associated with oxidosis, which, through lipid peroxidation, increases to membrane injury.
Animals↗