| 1. |
- Czub, Joanna, et al.
(författare)
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CALIBRATION OF LOW ENERGY X-RAY EXPERIMENTAL SETUP WITH STRONGLY FILTERED BEAM USING DATA FROM A SEMICONDUCTOR AND A THERMOLUMINESCENT DETECTORS
- 2019
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 185:2, s. 266-273
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Tidskriftsartikel (refereegranskat)abstract
- The calibration of low energy X-ray experimental setup with strongly filtered beam dedicated to radiobiological research was performed using the absorbed dose calculated from the data collected by two types detectors. For this purpose a semiconductor (Amptek, USA) and a thermoluminescent (Institute of Nuclear Physics, Krakow, Poland) detectors were applied. The absorbed dose in water values estimated by both detectors are in good agreement.
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| 2. |
- Czub, Joanna, et al.
(författare)
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Monte Carlo dosimetry using Fluka code and experimental dosimetry with Gafchromic EBT2 and XR-RV3 of self-built experimental setup for radiobiological studies with low-energy X-rays
- 2020
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Ingår i: International Journal of Radiation Biology. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 96:6, s. 718-733
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The aim of this research was to simulate self-built experimental setup for radiobiological research using X-ray diffraction C-tech tube and PW 3830 generator (PANalytical, Netherlands) and to calculate absorbed dose and to compare it with experimental dose measurements. The maximum X-ray energy was 60 keV.Materials and methods: Petri dish was specially adapted to hold biological cells during the irradiation process. Rotation of Petri dish ensured radiation homogeneity and effectiveness of rotation process was confirmed using EBT2 Gafchromic film. Monte Carlo simulation using Fluka 2011 2c.4 was used to model the setup and to calculate dose absorbed by live cells. The EBT2 and XR-RV3 Gafchromic films were used to estimate relative experimental absorbed dose.Results: The radiation homogeneity provided values with maximum deviation equal to +/- 3.5% from the average value and the absorbed dose rate was 0.9 Gy/min using simulation process and 1 Gy/min or 0.8 Gy/min using experimental methods (XR-RV3 and EBT2 Gafchromic film, respectively). All dose rate values show metrological compatibility.Conclusions: Influence of specially constructed Petri dish on absorbed dose was determined using simulations that showed that low-energy photons, emitted as characteristic line from borosilicate glass forming component of Petri dish, were source of increase in dose absorbed by cells. This experimental setup will be used to conduct radiobiological research.
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| 3. |
- Olsson, Erik, 1960, et al.
(författare)
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Hippocampal volumes in patients exposed to low-dose radiation to the basal brain. A case--control study in long-term survivors from cancer in the head and neck region.
- 2012
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Ingår i: Radiation oncology (London, England). - 1748-717X. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: BACKGROUND: An earlier study from our group of long time survivors of head and neck cancer who had received a low radiation dose to the hypothalamic-pituitary region, with no signs of recurrence or pituitary dysfunction, had their quality of life (QoL) compromised as compared with matched healthy controls. Hippocampal changes have been shown to accompany several psychiatric conditions and the aim of the present study was to test whether the patients' lowered QoL was coupled to a reduction in hippocampal volume. METHODS: Patients (11 men and 4 women, age 31--65) treated for head and neck cancer 4--10 years earlier and with no sign of recurrence or pituitary dysfunction, and 15 matched controls were included. The estimated radiation doses to the basal brain including the hippocampus (1.5 -- 9.3 Gy) had been calculated in the earlier study. The hippocampal volumetry was done on coronal sections from a 1.5 T MRI scanner. Measurements were done by two independent raters, blinded to patients and controls, using a custom method for computer assisted manual segmentation. The volumes were normalized for intracranial volume which was also measured manually. The paired t test and Wilcoxon's signed rank test were used for the main statistical analysis. RESULTS: There was no significant difference with respect to left, right or total hippocampal volume between patients and controls. All mean differences were close to zero, and the two-tailed 95% confidence interval for the difference in total, normalized volume does not include a larger than 8% deficit in the patients. CONCLUSION: The study gives solid evidence against the hypothesis that the patients' lowered quality of life was due to a major reduction of hippocampal volume.
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| 4. |
- Tyagi, Shweta, et al.
(författare)
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E2F activation of S phase promoters via association with HCF-1 and the MLL family of histone H3K4 methyltransferases.
- 2007
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Ingår i: Molecular Cell. - : Elsevier (Cell Press). - 1097-2765 .- 1097-4164. ; 27:1, s. 107-119
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Tidskriftsartikel (refereegranskat)abstract
- E2F transcriptional regulators control human-cell proliferation by repressing and activating the transcription of genes required for cell-cycle progression, particularly the S phase. E2F proteins repress transcription in association with retinoblastoma pocket proteins, but less is known about how they activate transcription. Here, we show that the human G1 phase regulator HCF-1 associates with both activator (E2F1 and E2F3a) and repressor (E2F4) E2F proteins, properties that are conserved in insect cells. Human HCF-1-E2F interactions are versatile: their associations and binding to E2F-responsive promoters are cell-cycle selective, and HCF-1 displays coactivator properties when bound to the E2F1 activator and corepressor properties when bound to the E2F4 repressor. During the G1-to-S phase transition, HCF-1 recruits the mixed-lineage leukemia (MLL) and Set-1 histone H3 lysine 4 methyltransferases to E2F-responsive promoters and induces histone methylation and transcriptional activation. These results suggest that HCF-1 induces cell-cycle-specific transcriptional activation by E2F proteins to promote cell proliferation.
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