Tomas Balharek

Heart rate recovery after exercise: relations to heart rate variability and complexity

Physical exercise is associated with parasympathetic withdrawal and increased sympathetic activity resulting in heart rate increase. The rate of post-exercise cardiodeceleration is used as an index of cardiac vagal reactivation. Analysis of heart rate variability (HRV) and complexity can provide useful information about autonomic control of the cardiovascular system. The aim of the present study was to ascertain the association between heart rate decrease after exercise and HRV parameters. Heart rate was monitored in 17 healthy male subjects (mean age: 20 years) during the pre-exercise phase (25 min supine, 5 min standing), during exercise (8 min of the step test with an ascending frequency corresponding to 70% of individual maximal power output) and during the recovery phase (30 min supine). HRV analysis in the time and frequency domains and evaluation of a newly developed complexity measure - sample entropy - were performed on selected segments of heart rate time series. During recovery, heart rate decreased gradually but did not attain pre-exercise values within 30 min after exercise. On the other hand, HRV gradually increased, but did not regain rest values during the study period. Heart rate complexity was slightly reduced after exercise and attained rest values after 30-min recovery. The rate of cardiodeceleration did not correlate with pre-exercise HRV parameters, but positively correlated with HRV measures and sample entropy obtained from the early phases of recovery. In conclusion, the cardiodeceleration rate is independent of HRV measures during the rest period but it is related to early post-exercise recovery HRV measures, confirming a parasympathetic contribution to this phase.

Amplification of 3q26 and 5p15 regions in cervical intraepithelial neoplasia

To analyze different amplification patterns of 3q26 and 5p15 regions in low‐grade and high‐grade cervical intraepithelial neoplasia.

A novel JAK2 exon 12 mutation identified in the retrospective analysis of paraffin-embedded tissues of polycythemia vera patients.

The aim of the study was to screen formalin-fixed, paraffin-embedded tissues of polycythemia vera patients for the presence of JAK2V617F and JAK2 exon 12 mutations. Of 64 cases, 60 were positive for JAK2V617F mutation using allele-specific polymerase chain reaction (PCR). Using modified allele-specific PCR, samples of 4 JAK2V617F-negative patients were analyzed for the presence of JAK2 exon 12 mutations. In one case, we found a PCR product matching with allele-specific primer, which was designed to detect the N542-E543del mutation. Surprisingly, in the result sequence we have detected another recently described mutation, R541-E543delinsK. In the other 3 JAK2V617F-negative patients, allele-specific PCR for the detection of JAK2 exon 12 mutations did not yield any product. However, in 1 case, the sequencing of JAK2 exon 12 PCR product revealed a novel mutation, H538-K539delinsF. We confirmed that paraffin-embedded tissues represent a valuable source of DNA, which can be used in diagnostics of both JAK2 exon 12 and exon 14 mutations and we described 1 novel JAK2 exon 12 mutation.

Differential mRNA expression of the main apoptotic proteins in normal and malignant cells and its relation to in vitro resistance

BackgroundApoptosis plays an important role in the development and homeostasis of multicellular organisms and its deregulation may result in many serious diseases, including cancer. Now it is clear that some oncogenic mutations disrupt apoptosis, leading to tumour initiation, progression or metastasis. Here, expression of apoptotic genes in context of drug resistance was investigated.MethodsWe examined total of 102 samples from leukemic patients (n = 60) and patients with solid tumours (n = 42). We used RT-PCR to determine the levels of mRNA expression and the in vitro chemoresistance of leukemic cells was evaluated using the MTT assay.ResultsWe found statistically significant increase in mRNA expression of all investigated proteins (p53, BAX, Bcl-2 and Bcl-XL) between the leukemia samples and leukocytes from healthy volunteers. We did not find any significant difference in mRNA levels among the solid tumour samples. Notably, we showed a significant positive correlation in both leukemic and solid tumour patient groups between p53 and BAX mRNA. We found that the highest values for the Bcl-2/BAX ratio were in solid tumours in comparison to leukemic cells or normal leukocytes. Moreover, we assessed the impact of p53 and BAX mRNA levels on the sensitivity of the leukemic cells to selected cytostatics.ConclusionsElevated levels of p53 and BAX mRNA may indicate cellular response to possible changes in genomic DNA integrity associated with malignant transformation. We suggest that the BAX gene is regulated by the p53 protein but the initiation of apoptosis through the transcription activation of BAX is blocked by the high levels of Bcl-2. Given that the apoptosis resistance mechanisms are different among oncological patients as well as stages of identical malignancy cases, personalized and specific combination therapy is proposed to be more effective in clinical application.

Different amplification patterns of 3q26 and 5p15 regions in cervical intraepithelial neoplasia and cervical cancer

PURPOSE The aim of this study was to evaluate and correlate the amplification of chromosomal regions 3q26 and 5p15 in different cytological and histological subgroups of patients and to compare the sensitivity and specificity of amplification tests with cytology, colposcopy and HPV status. METHODS The work was conducted at the Department of Obstetrics and Gynaecology in cooperation with the Institute of Pathological Anatomy, JFM CU in Martin and UNM during years 2013-2016. Prospective longitudinal study included 131 patients. We focused on the FISH diagnosis of the amplification of regions encoding the components of telomerase enzyme (3q26, 5p15) in cytology specimens. We manually evaluated 100 atypical cells per slide and analysed the amplification patterns. Correlations between cytological, histological, HPV DNA results and amplification patterns of chromosomal regions 3q26 and 5p15 were analysed by chi-squared test and non-parametric Man - Whitney U test. RESULTS The results showed that the amplification of chromosomal regions increases with the degree of dysplasia toward the invasive disease (p < 0.001). Whereas the increase in the amplification of 3q26 is noticeable already at CIN 2 + lesions (p < 0.01), 5p15 amplification is shifted up toward CIN 3/CIS (p < 0.001) and cervical cancer. Amplification of selected regions correlated with each other and also with hrHPV-positive status (p < 0.01). CONCLUSION The analysis of the amplification of 3q26 and 5p15 regions may serve in the future for the differential diagnosis of cervical lesions and to determine their malignant potential. High specificity of these tests can improve the excellent sensitivity of HPV DNA test.

DNA methylation as mechanism of apoptotic resistance development in endometrial cancer patients

DNA methylation is a significant epigenetic modification which plays a key role in regulation of gene expression and influences functional changes in endometrial tissue. Aberrant DNA methylation changes result in deregulation of important apoptotic proteins during endometrial carcinogenesis and apoptosis resistance development. Evading apoptosis is still a major problem in the successful treatment of endometrial cancer patients. The aim of our study was to examine the promoter DNA methylation changes in 22 apoptosis-associated genes in endometrioid endometrial cancer patients, precancerous lesions and healthy tissue from various normal menstrual cycle phases using a unique pre-designed methylation platform. We observed as the first a significant difference in promoter DNA methylation status in genes: BCL2L11 (p < 0.001), CIDEB (p < 0.03) and GADD45A (p < 0.05) during endometrial carcinogenesis and BIK gene (p < 0.03) in different phases of normal menstrual cycle. The results of our study indicate that deregulation of mitochondrial apoptotic pathway can considerably contributes to the apoptosis resistance development and may be helpful in identifying of new potent biomarkers in endometrial cancer.