Effect of aging on formation of reactive oxygen species by mitochondria of rat heart

Mitochondrial electron transport chain is thought to be a major source of reactive oxygen species (ROS) during aging. However, this view is supported mainly by accumulation of mitochondrial oxidative damage with age and the exact sites of ROS formation remains unknown. In the present study, we measured rate of ROS formation using 2',7'-dichlorofluorescein (DCF) probe in cardiac mitochondria from adult (6-month-old), old (15-month-old) and senescent (26-month-old) rats. In mitochondria oxidizing complex II substrate, succinate, the rate of ROS formation progressively increased with age. In the presence of complex I inhibitor rotenone or complex III inhibitor antimycin A, the rate ROS formation significantly decreased, but even the combination of inhibitors could not fully prevent generation of ROS. Age-dependent increase of ROS formation was accompanied by a loss of thiol groups, tryptophan degradation and increased lipid peroxidation. These data suggest that in addition to complex I and complex II other mitochondrial sites can contribute to accelerated ROS generation and oxidative damage during aging.

Frequency of polymorphism -262 c/t in catalase gene and oxidative damage in Slovak children with bronchial asthma

INTRODUCTION

Bronchial asthma is a complex disease in which genetic factors, environmental factors and oxidative damage are responsible for the initiation and modulation of disease progression. If antioxidant mechanisms fail, reactive oxygen species damage the biomolecules followed by progression of the disease. Catalase is one of the most important endogenous enzymatic antioxidants. In the present study, we examined the hypothesis that increased oxidative damage and polymorphism in the CAT gene (-262 promoter region, C/T) are associated with childhood bronchial asthma.

PATIENTS AND METHODS

Genotyping of the polymorphisms in the CAT gene in healthy (249) and asthmatic children (248) was performed using polymerase chain reaction-restriction fragment length polymorphism. Markers of oxidative damage: content of sulfhydryl groups and thiobarbituric acid-reactive substances were determined by spectrophotometry in children.

RESULTS

The TT genotype of catalase was more frequent among the asthmatic patients (22.6%) than in healthy children (4.8%) (odds ratio=5.63; 95% confidence interval=2.93-10.81, P<.001). The amount of sulfhydryl groups decreased significantly and conversely, the content of thiobarbituric acid-reactive substances increased significantly in bronchial asthma and in catalase TT genotype compared to other catalase genotypes of this gene.

CONCLUSIONS

These results suggest that catalase polymorphism might participate in development of bronchial asthma and in enhanced oxidative damage in asthmatic children. Genetic variation of enzymatic antioxidants may modulate disease risk.

Effect of normobaric oxygen treatment on oxidative stress and enzyme activities in guinea pig heart

Normobaric oxygen (NBO) therapy is commonly applied for the treatment of various diseases, including myocardial infarctions, but its effectiveness is controversial. Potential adverse effects of hyperoxia are related to excessive formation of free radicals. In the present study we examined the effect of 60-h NBO treatment on lipid peroxidation (LPO), activity of manganese superoxide dismutase (Mn-SOD) and mitochondrial enzymes of energy metabolism in guinea pig heart. NBO treatment resulted in significant accumulation of thiobarbituric acid reactive substances and loss of Mn-SOD activity despite slight elevation of Mn-SOD protein content. Activity of electron transport chain complex III decreased significantly, while activity of complex IV was slightly elevated and citrate synthase was unchanged. LPO, inhibition of Mn-SOD and complex III activities were more pronounced when inhaled oxygen was partially enriched with superoxide radical. In contrast, when O(2) was enriched with oxygen cation (O(2)●+), LPO and loss of Mn-SOD activity were prevented. Complex III activity in the O(2)●+-treated group remained depressed but activities of complex IV and citrate synthase were elevated. These data suggest that NBO treatment is associated with myocardial oxidative damage and attenuation of antioxidant defense, but these adverse effects can be partially attenuated by inhalation of O(2) enriched with oxygen cation.

Age-associated changes in Ca(2+)-ATPase and oxidative damage in sarcoplasmic reticulum of rat heart

Altered Ca(2+) handling may be responsible for the development of cardiac contractile dysfunctions with advanced age. In the present study, we investigated the roles of oxidative damage to sarcoplasmic reticulum (SR) and expression of Ca(2+)-ATPase (SERCA 2a) and phospholamban in age-associated dysfunction of cardiac SR. SR vesicles were prepared from hearts of 2-, 6-, 15-, and 26-month-old Wistar rats. Although activity of Ca(2+)-ATPase decreased with advancing age, no differences in relative amounts of SERCA 2a and phospholamban protein were observed. On the other hand, significant accumulation of protein oxidative damage occurred with aging. The results of this study suggest that age-related alteration in Ca(2+)-ATPase activity in the rat heart is not a consequence of decreased protein levels of SERCA 2a and phospholamban, but could arise from oxidative modifications of SR proteins. Cellular oxidative damage caused by reactive oxygen species could contribute to age-related alternations in myocardial relaxation.

Microsomal epoxide hydrolase polymorphisms, cigarette smoking and prostate cancer risk in the Slovak population

Polymorphisms in tobacco carcinogen metabolizing enzymes may generate interindividual variations towards the risk of developing prostate cancer. One of these enzymes is microsomal epoxide hydrolase (EPHX1) which metabolizes polycyclic aromatic hydrocarbons, or PAH, carcinogens found in cigarette smoke. The activity of this enzyme is affected by two polymorphisms, a substitution of Tyr113 by His in exon 3 and a substitution of His139 by Arg in exon 4. The aim of this study was to use a population-based case-control study to investigate whether or not such genetic polymorphisms in EPHX1 gene can modify the relationship between smoking status and the risk of developing prostate cancer. We used restriction fragment length polymorphism, or PCR-RFLP to determine EPHX1 genotypes in subjects comprising 194 patients with histologically verified prostate cancer and 305 healthy individuals as control. We found no overall association between prostate cancer risk and functional polymorphisms of EPHX1 gene in exon 3 and exon 4. We further analysed the association between the EPHX1 genotypes and smoking. Smokers carrying the exon 3 Tyr/Tyr and Tyr/His genotypes were at no significant risk compared to non-smokers with the "rapid" Tyr/Tyr genotype. By contrast, a significant interaction of smoking and the exon 4 polymorphism was present.

Hippocampal neurometabolite changes in depression treatment: a (1)H magnetic resonance spectroscopy study

Previous studies using magnetic resonance spectroscopy have related abnormalities in hippocampal metabolism to depression. Current evidence is consistent with the conclusion that the hippocampal formation plays an important role in the presentation of depressive symptoms. Eighteen adult patients with major depressive disorder, aged 20 to 60 years, underwent magnetic resonance spectroscopy of the hippocampus during a period of depressive symptomatology and after 7-11 weeks of antidepressant medication with at least 50% reduction in the Montgomery-Åsberg Depression Rating Scale ()MADRS score. During therapy, we found a significantly decreased Lac/Cr ratio in the left hippocampus. The Ins/Cr ratio showed a significant negative correlation with the severity of depression as assessed by the MADRS at baseline. Moreover, we found a negative association of NAA/Cho with age and a positive association of Cho/Cr with age, both on the left and right sides at baseline. In light of our findings and previous studies results we hypothesize that mitochondrial dysfunction leading to predominantly anaerobic glycolysis in connection with the intracellular signaling pathways disturbances and decreased astrocytic function/number might subsequently lead to decreased brain neuroplasticity in depression. These mechanisms could be positively influenced by antidepressant treatment with selective serotonin or norepineprine reuptake inhibitors, with potential effects on untimely neuronal aging in depression.

Radiation-induced long-term alterations in hippocampus under experimental conditions

BACKGROUNDS

The aim of the present study was to investigate the effect of ionizing radiation on the cell population that co-forms hippocampal formation in an adult rat brain.

MATERIALS AND METHODS

Adult male Wistar rats were exposed to whole-body irradiation with fractionated doses of gamma rays (the total dose of 4 Gy). Thirty, 60 and 90 days after irradiation the cell-specific types housed in the CA1, CA3 subregions and adjacent layers were labelled using immunohistochemistry for specific cell phenotypes; Ki-67 marker was used for proliferating cells and GFAP for detection of astrocytes.

RESULTS

During the 30th day post-exposure, a considerable increase in the numbers of Ki-67-positive cells was seen. Moreover, significant decline in the density of neurons, mostly in the CA1 subregion, was observed on the 60th day. Slight overaccumulation of Ki-67-positive cells was seen in CA1 area 90 days after radiation treatment. Temporary decrease of GFAP-positive astrocytes was seen thirty days after irradiation, followed by their subsequent increase 60 days after exposure. Secondary decrease of GFAP-positive cells in both of regions was found in the group surviving 90 days post-irradiation.

CONCLUSION

Results showed that radiation response of neurons and astrocytes that form the adult hippocampus may play contributory role in the development of prognostically unfavourable adverse radiation-induced late effect.

Why mitochondria are excellent targets for cancer therapy

New insights into cancer cells - specific biological pathways are urgently needed to promote development of exactly targeted therapeutics. The role of oncoproteins and tumor suppressor proteins in proliferative signaling, cell cycle regulation and altered adhesion is well established. Chemicals, viruses and radiation are also generally accepted as agents that commonly induce mutations in genes encoding these cancer-inducing proteins, thereby giving rise to cancer. More recent evidence indicates the importance of two additional key factors imposed on proliferating cells - hypoxia and/or lack of glucose. These two additional triggers can initiate and promote the process of malignant transformation, when a low percentage of cells escape cellular senescence. Disregulated cell proliferation leads to formation of cellular masses that extend beyond the resting vasculature, resulting in oxygen and nutrient deprivation. Resulting hypoxia triggers a number of critical adaptations that enable cancer cell survival. The process of apoptosis is suppressed and glucose metabolism is altered. Recent investigations suggest that oxygen depletion stimulates mitochondria to compensate increased reactive oxygen species (ROS). It activates signaling pathways, such as hypoxia-inducible factor 1, that promote cancer cell survival and tumor growth. During the last decade, mitochondria have become key organelles involved in chemotherapy-induced apoptosis. Therefore, the relationship between mitochondria, ROS signaling and activation of survival pathways under hypoxic conditions has been the subject of increased study. Insights into mechanisms involved in ROS signaling may offer novel ways to facilitate discovery of cancer-specific therapies.

Endometrial aromatase mRNA as a possible screening tool for advanced endometriosis and adenomyosis

Endometriosis (ENDs) and adenomyosis (ADNs) are estrogen-dependent diseases. The aim of this study was to determine the clinical usefulness of examining endometrial biopsy specimens for aromatase cytochrome P450 (CYP19) as a diagnostic importance for endometriosis and adenomyosis. In general, the RT-PCR analyses of 101 samples revealed increased aromatase mRNA expression in eutopic endometrium in women with endometriosis and adenomyosis compared to healthy controls (p = 0.0002). The highest number of positive cases (93.3%) of CYP19 mRNA expression was detected in women with advanced disease stages. Concrete expression of CYP19 mRNA level in controls was 0.68 compared to patients with ADNs (1.21), ENDsL stage I-II (1.15) and ENDsA stage III-IV (1.65) (p < 0.0001), respectively. The possible influence of increased body mass index on aromatase expression in each group showed in controls an insignificant slight increase of aromatase expression, contrary to cases where this trend was the opposite. The results point to the higher (2.45-fold) difference in aromatase expression in patients with endometriosis stage III-IV compared to controls and provide direct evidence that screening for eutopic endometrial aromatase expression in combination with clinical data could be of discriminative value in the prediction of estrogen-dependent diseases, independent from body mass index.

[Five year-results of chemoresistance testing in cancer patients]

BACKGROUNDS

Translational medicine is a medical field encompassing basic research and development of new diagnostic and therapeutic strategies for clinical practice. The present scientific paper focuses on our previous experience in the field of chemoresistance testing in patients with oncological diseases.

MATERIAL AND METHODS

Since 2005, we sampled 71 patients with a leukaemia (AML, ALL and CML) and 92 patients with a solid tumour (lung and gastrointestinal tract cancer). Malignant cell in vitro drug resistance testing was carried out using cytotoxic methyl-thiazol tetrazolium (MTT) assay.

RESULTS

Based on the LC50 (lethal concentration of a drug killing 50% of cell population), we found that patients with acute myeloblastic leukaemia exhibit a greater degree of resistance than patients with acute lymphoblastic leukaemia. In patients with bronchogenic carcinomas, primary resistance to cisplatin was identified in 28% of tested samples, paclitaxel 36%, vincristine 50%, etoposide 56%, vinorelbine 57%, topotecan 62%, gemcitabine 77% and dacarbazine 86%.

CONCLUSION

In vitro tests with gastrointestinal tract cancers also suggested high effectiveness of cisplatin (with the exception of gastric carcinoma) that was comparable with 5-fluorouracil. Even though the MTT assay has some limitations (insufficient number of vital cells, possible contamination by non-malignant cells, etc.), this in vitro method proved very effective in testing malignant cell resistance to clinically used cytostatics.

Effects of aging on activities of mitochondrial electron transport chain complexes and oxidative damage in rat heart

Mitochondrial dysfunction and accumulation of oxidative damage have been implicated to be the major factors of aging. However, data on age-related changes in activities of mitochondrial electron transport chain (ETC) complexes remain controversial and molecular mechanisms responsible for ETC dysfunction are still largely unknown. In this study, we examined the effect of aging on activities of ETC complexes and oxidative damage to proteins and lipids in cardiac mitochondria from adult (6-month-old), old (15-month-old) and senescent (26-month-old) rats. ETC complexes I-IV displayed different extent of inhibition with age. The most significant decline occurred in complex IV activity, whereas complex II activity was unchanged in old rats and was only slightly reduced in senescent rats. Compared to adult, old and senescent rat hearts had significantly higher levels of malondialdehyde, 4-hydroxynonenal (HNE) and dityrosine, while thiol group content was reduced. Despite marked increase in HNE content with age (25 and 76 % for 15- and 26-month-old rats, respectively) Western blot analysis revealed only few HNE-protein adducts. The present study suggests that non-uniform decline in activities of ETC complexes is due, at least in part, to mitochondrial oxidative damage; however, lipid peroxidation products appear to have a limited impact on enzyme functions.

Gene polymorphisms of biotransforming enzymes (GSTs) and their association with lung cancer in the Slovakian population

Objective

The aim of present study was to present the results of a case-control study focused on genetic polymorphisms of selected Phase II metabolizing enzymes (GSTM1, T1, and P1) and to investigate the association of these polymorphisms with lung cancer risk in the Slovakian population.

Material and methods

The study encompassed 160 lung cancer cases and 220 controls. DNA was extracted from peripheral blood leukocytes, and the polymorphisms of GSTM1, GSTT1 and GSTP1 enzymes were determined by PCR-based methods. We determined the genotype distribution of all these genes and their combinations. The association between specific genotypes and the development of lung cancer were examined using logistic regression analysis to calculate odds ratios (OR) and 95% confidence intervals (CI).

Results

We found that the GSTM1 null genotype (OR = 1.6; 95% CI = 1.03-2.4; χ² = 4.08, and P = 0.04) was associated with elevated risk. A significant correlation also was found for the combined genotypes of GSTM1 null and GSTP1 Ile/Val and Val/Val (OR = 2.01; 95% CI = 1.1-6.1; χ² = 3.6, and P = 0.02) and GSTM1 null and GSTT1 positive (OR = 2.00; 95% CI = 1.2-3.2; χ² = 7.3, and P = 0.006).

Conclusions

We conclude that the genotype of metabolizing enzymes and allelic combinations underscore the risk for lung cancer. Individual risk assessment may be further improved by increasing the number of polymorphisms studied and combining them with the traditional epidemiological risk factor.

Effects of long-term oxygen treatment on alpha-ketoglutarate dehydrogenase activity and oxidative modifications in mitochondria of the guinea pig heart

OBJECTIVE

Oxygen therapy is used for the treatment of various diseases, but prolonged exposure to high concentrations of O(2) is also associated with formation of free radicals and oxidative damage.

METHODS

In the present study we compared alpha-ketoglutarate dehydrogenase (KGDH) activity and mitochondrial oxidative damage in the hearts of guinea pigs after long-term (17 and 60 h) oxygenation with 100% normobaric O(2) and with partially negatively (O(2 neg)) or positively (O(2 posit)) ionized oxygen.

RESULTS

Inhalation of O(2) led to significant loss in KGDH activity and thiol group content and accumulation of bityrosines. Inhalation of O(2 neg) was accompanied by more pronounced KGDH inhibition, possibly due to additional formation of protein-lipid conjugates. In contrast, O(2 posit) prevented loss in KGDH activity and diminished mitochondrial oxidative damage.

CONCLUSIONS

These findings suggest that oxygen treatment is associated with impairment of heart energy metabolism and support the view that inhalation of O(2 posit) optimizes the beneficial effects of oxygen therapy.

Serum level of IGFBP3 and IGF1/IGFBP3 molar ratio in addition to PSA and single nucleotide polymorphism in PSA and CYP17 gene may contribute to early diagnostics of prostate cancer

The aim of the paper is to determine whether IGF1, IGFBP3 and IGF1/IGFBP3 molar ratio in addition to PSA and one-nucleotide polymorphism in PSA and CYP17 gene might contribute to early diagnostics of prostate cancer (PCa). Serum level of PSA, IGF1 and IGFBP3 in the group of 158 individuals (92 PCa and 66 controls) was examined by RIA method and IGF1/IGFBP3 was calculated. PCR RLFP method was used to examine one- nucleotide polymorphism in PSA and CYP 17 gene. The results suggest that serum level of IGF1 over 95% CI did not increase relative risk of PCa development in overall group, not even regarding to particular investigated genotypes, not even if individuals with genotype AG+A1A1, AG+A1A2, GG+A1A1 and GG+A1A2 were evaluated. Serum level of IGFBP3 under 95% CI increased PCa relative risk in overall group(chi(2) = 10,03, p= 0,001, OR 3,12, 95% CI 1,44-6,93), as well as regarding to one-nucleotide polymorphism in individuals with PSA genotype AG(chi(2) = 4,72 p= 0,029, OR 2,87, 95% CI 01,09-7,49) and CYP 17 genotype A1A1(chi(2) = 3,76 p= 0,052, OR 2,57, 95% CI 0,97-6,75). The association between frequencies of occurrence of PCa and higher IGF1/IGFBP3 molar ratio was not confirmed, nor for gene polymorphism in PSA and CYP17, however OR (chi(2) = 1,58, p= 0,208, OR 1,67, 95% CI 0,75-3,71) was more than 1, nor in combination AG+A1A1,AG+ A1A2. Serum level of IGFBP3 and IGF1/IGFBP3 molar ratio in addition to PSA and gene polymorphism in PSA and CYP17 gene might contribute to early diagnostics of PCa. Further research is needed to prove, whether serum level of IGFBP3 in addition to PSA determines the prognosis and progression of PCa.

Oxidative stress induced in rat brain by a combination of 3-nitropropionic acid and global ischemia

In our investigation, we describe the complex model of brain oxidative stress consisted of combination of experimental brain ischemia and energy metabolism violation induced by irreversible inhibitor of mitochondrial succi-nate dehydrogenase, 3-nitropropionate (3-NPA). 3-NPA causes selective degeneration of striatum neurons, which is extremely sensitive to energy deficit. This complex model allows revealing not only biochemical but also neurological symptoms in experimental animals that permits proper estimation of protective effect of different drugs on animal status. Combination of global ischemia induced by 3-vessel occlusion of major arteries supplys rat brain and subsequent 5-day reperfusion with intraperitoneal injection of 3-nitropropionic acid induces vigorous oxidative stress in brain tissues accompanied by evident neurological symptoms in Wistar rats. Such a combination of damaging factors may be considered as a new complex experimental model of brain oxidative stress permitting the evaluation of neuroprotective effect of potential therapeutic agents. Using this model, protective effect of neuropeptide carnosine was demonstrated which is in agreement with previous data.

Association of oxidative stress and GST-T1 gene with childhood bronchial asthma

There is increasing evidence that bronchial asthma is associated with increased oxidative stress. Reactive oxygen species are produced in each organism as by-products of several essential reactions and can damage biomolecules. Asthma is a complex chronic inflammatory disorder of the airways, with many candidate genes suspected as being important in its development. Glutathione S-transferase (GST) is such a gene due to its role in protection against oxidative stress. In the present study, we examined the hypothesis that increased oxidative stress and polymorphism in the GST-T1 gene are associated with childhood asthma. We found that the amount of sulfhydryl groups significantly decreased and the content of thiobarbituric acid-reactive substances increased in the group of asthmatic children, compared with healthy controls. The GST-T1 null genotype was more frequent among the asthma patients. These results suggest that the GST-T1 null genotype and increased oxidative stress may play a role in the asthma pathogenesis in children.

Polymorphisms of glutathione-S-transferase M1, T1, P1 and the risk of prostate cancer: a case-control study

Background

It has been suggested that polymorphisms in glutathione-S-transferases (GST) could predispose to prostate cancer through a heritable deficiency in detoxification pathways for environmental carcinogens. Yet, studies linking GST polymorphism and prostate cancer have so far failed to unambiguously establish this relation in patients. A retrospective study on healthy, unrelated subjects was conducted in order to estimate the population GST genotype frequencies in the Slovak population of men and compare our results with already published data (GSEC project-Genetic Susceptibility to Environmental Carcinogens). A further aim of the study was to evaluate polymorphisms in GST also in patients with prostate cancer in order to compare the evaluated proportions with those found in the control subjects.

Methods

We determined the GST genotypes in 228 healthy, unrelated subjects who attended regular prostate cancer screening between May 2005 and June 2007 and in 129 histologically verified prostate cancer patients. Analysis for the GST gene polymorphisms was performed by PCR and PCR-RFLP.

Results

We found that the GST frequencies are not significantly different from those estimated in a European multicentre study or from the results published by another group in Slovakia. Our results suggest that Val/Val genotype of GSTP1 gene could modulate the risk of prostate cancer, even if this association did not reach statistical significance. We did not observe significantly different crude rates of the GSTM1 and GSTT1 null genotypes in the men diagnosed with prostate cancer and those in the control group.

Conclusion

Understanding the contribution of GST gene polymorphisms and their interactions with other relevant factors may improve screening diagnostic assays for prostate cancer. We therefore discuss issues of study feasibility, study design, and statistical power, which should be taken into account in planning further trials.

Mitochondrial calcium transport and mitochondrial dysfunction after global brain ischemia in rat hippocampus

Here we report effect of ischemia-reperfusion on mitochondrial Ca2+ uptake and activity of complexes I and IV in rat hippocampus. By performing 4-vessel occlusion model of global brain ischemia, we observed that 15 min ischemia led to significant decrease of mitochondrial capacity to accumulate Ca2+ to 80.8% of control whereas rate of Ca2+ uptake was not significantly changed. Reperfusion did not significantly change mitochondrial Ca2+ transport. Ischemia induced progressive inhibition of complex I, affecting final electron transfer to decylubiquinone. Minimal activity of complex I was observed 24 h after ischemia (63% of control). Inhibition of complex IV activity to 80.6% of control was observed 1 h after ischemia. To explain the discrepancy between impact of ischemia on rate of Ca2+ uptake and activities of both complexes, we performed titration experiments to study relationship between inhibition of particular complex and generation of mitochondrial transmembrane potential (DeltaPsi(m)). Generation of a threshold curves showed that complex I and IV activities must be decreased by approximately 40, and 60%, respectively, before significant decline in DeltaPsi(m) was documented. Thus, mitochondrial Ca2+ uptake was not significantly affected by ischemia-reperfusion, apparently due to excess capacity of the complexes I and IV. Inhibition of complex I is favourable of reactive oxygen species (ROS) generation. Maximal oxidative modification of membrane proteins was documented 1 h after ischemia. Although enhanced formation of ROS might contribute to neuronal injury, depressed activities of complex I and IV together with unaltered rate of Ca2+ uptake are conditions favourable of initiation of other cell degenerative pathways like opening of mitochondrial permeability transition pore or apoptosis initiation, and might represent important mechanism of ischemic damage to neurones.

Rat tau proteome consists of six tau isoforms: implication for animal models of human tauopathies

Human brain encompasses six tau isoforms, containing either three (3R) or four (4R) repeat domains, all of which participate in the pathogenesis of human tauopathies. To investigate the role of tau protein in the disease, transgenic rat models have been created. However, unlike humans, it has been suggested that rat brain expresses only three 4R tau isoforms. Because of the significance of the number of tau isoforms for faithful reproducibility of neurofibrillary pathology in transgenic rat models, we reopened this issue. Surprisingly, our results showed that adult rat brain contains six tau isoforms like humans. Protein expression of 4R tau isoforms was ninefold higher than 3R isoforms. Furthermore, the protein levels of tau isoforms with none, one or two N-terminal inserts were 30%, 35%, and 35% of total tau, respectively. Moreover, amount and ratio of tau isoforms were developmentally regulated. The levels of 4R tau isoforms progressively increased from early postnatal period until adulthood, whereas the expression of 3R tau isoforms reached maximum at P10 and then gradually declined. Our results show that rat brain encompasses full tau proteome similar to humans. These findings support the use of rat as an animal model in human tauopathies research.

Transcription of genes of p53-dependent apoptosis in acute leukaemia

Tumour suppressor protein p53 prevents cancer development through various mechanisms, including the induction of apoptosis. We demonstrated that acute leukaemia, myeloblastic (AML) and lymphoblastic (ALL), is associated with significantly elevated levels of p53 and Bax mRNA in leukaemic cells. Regarding ALL, significantly elevated levels of Bcl-xL mRNA may explain the relative resistance of ALL cells to p53-dependent apoptosis. Altered alternative processing of Bcl-x and myeloid cell leukaemia-1 (MCL1) primary transcripts were observed in the case of AML and AML and ALL, respectively. We assumed that increased glyceraldehyde-3-phosphate dehydrogenase (gapdh) transcription and decreased MCL1s mRNA were not fully responsible for the dysregulation of p53-dependent apoptosis in the case of AML. In addition, transcription of hsp70.1 and Bcl-2 producing anti-apoptotic proteins was not affected in acute leukaemia.