Comparison of RBE values of high- LET α-particles for the induction of DNA-DSBs, chromosome aberrations and cell reproductive death

<p>Abstract</p> <p>Background</p> <p>Various types of radiation effects in mammalian cells have been studied with the aim to predict the radiosensitivity of tumours and normal tissues, e.g. DNA double strand breaks (DSB), chromosome aberrations and cell reproductive inactivation. However, variation in correlations with clinical results has reduced general application. An additional type of information is required for the increasing application of high-LET radiation in cancer therapy: the Relative Biological Effectiveness (RBE) for effects in tumours and normal tissues. Relevant information on RBE values might be derived from studies on cells in culture.</p> <p>Methods</p> <p>To evaluate relationships between DNA-DSB, chromosome aberrations and the clinically most relevant effect of cell reproductive death, for ionizing radiations of different LET, dose-effect relationships were determined for the induction of these effects in cultured SW-1573 cells irradiated with gamma-rays from a Cs-137 source or with α-particles from an Am-241 source. RBE values were derived for these effects. Ionizing radiation induced foci (IRIF) of DNA repair related proteins, indicative of DSB, were assessed by counting gamma-H2AX foci. Chromosome aberration frequencies were determined by scoring fragments and translocations using premature chromosome condensation. Cell survival was measured by colony formation assay. Analysis of dose-effect relations was based on the linear-quadratic model.</p> <p>Results</p> <p>Our results show that, although both investigated radiation types induce similar numbers of IRIF per absorbed dose, only a small fraction of the DSB induced by the low-LET gamma-rays result in chromosome rearrangements and cell reproductive death, while this fraction is considerably enhanced for the high-LET alpha-radiation. Calculated RBE values derived for the linear components of dose-effect relations for gamma-H2AX foci, cell reproductive death, chromosome fragments and colour junctions are 1.0 ± 0.3, 14.7 ± 5.1, 15.3 ± 5.9 and 13.3 ± 6.0 respectively.</p> <p>Conclusions</p> <p>These results indicate that RBE values for IRIF (DNA-DSB) induction provide little valid information on other biologically-relevant end points in cells exposed to high-LET radiations. Furthermore, the RBE values for the induction of the two types of chromosome aberrations are similar to those established for cell reproductive death. This suggests that assays of these aberrations might yield relevant information on the biological effectiveness in high-LET radiotherapy.</p

cGMP-Dependent Protein Kinase Type I Is Implicated in the Regulation of the Timing and Quality of Sleep and Wakefulness

Many effects of nitric oxide (NO) are mediated by the activation of guanylyl cyclases and subsequent production of the second messenger cyclic guanosine-3′,5′-monophosphate (cGMP). cGMP activates cGMP-dependent protein kinases (PRKGs), which can therefore be considered downstream effectors of NO signaling. Since NO is thought to be involved in the regulation of both sleep and circadian rhythms, we analyzed these two processes in mice deficient for cGMP-dependent protein kinase type I (PRKG1) in the brain. Prkg1 mutant mice showed a strikingly altered distribution of sleep and wakefulness over the 24 hours of a day as well as reductions in rapid-eye-movement sleep (REMS) duration and in non-REM sleep (NREMS) consolidation, and their ability to sustain waking episodes was compromised. Furthermore, they displayed a drastic decrease in electroencephalogram (EEG) power in the delta frequency range (1–4 Hz) under baseline conditions, which could be normalized after sleep deprivation. In line with the re-distribution of sleep and wakefulness, the analysis of wheel-running and drinking activity revealed more rest bouts during the activity phase and a higher percentage of daytime activity in mutant animals. No changes were observed in internal period length and phase-shifting properties of the circadian clock while chi-squared periodogram amplitude was significantly reduced, hinting at a less robust oscillator. These results indicate that PRKG1 might be involved in the stabilization and output strength of the circadian oscillator in mice. Moreover, PRKG1 deficiency results in an aberrant pattern, and consequently a reduced quality, of sleep and wakefulness, possibly due to a decreased wake-promoting output of the circadian system impinging upon sleep

Revealing Dissociable Attention Biases in Chronic Smokers Through an Individual-Differences Approach

Addiction is accompanied by attentional biases (AB), wherein drug-related cues grab attention independently of their perceptual salience. AB have emerged in different flavours depending on the experimental approach, and their clinical relevance is still debated. In chronic smokers we sought evidence for dissociable attention abnormalities that may play distinct roles in the clinical manifestations of the disorder. Fifty smokers performed a modified visual probe-task measuring two forms of AB and their temporal dynamics, and data on their personality traits and smoking history/ status were collected. Two fully dissociable AB effects were found: A Global effect, reflecting the overall impact of smoke cues on attention, and a Location-specific effect, indexing the impact of smoke cues on visuospatial orienting. Importantly, the two effects could be neatly separated from one another as they: (i) unfolded with dissimilar temporal dynamics, (ii) were accounted for by different sets of predictors associated with personality traits and smoking history and (iii) were not correlated with one another. Importantly, the relevance of each of these two components in the single individual depends on a complex blend of personality traits and smoking habits, a result that future efforts addressing the clinical relevance of addiction-related AB should take into careful consideration.This study was supported by funding provided by the University of Verona to CDL, CC and L

A miR-200b/200c/429-Binding Site Polymorphism in the 3′ Untranslated Region of the AP-2α Gene Is Associated with Cisplatin Resistance

The transcription factor AP-2α functions as a tumor suppressor by regulating various genes that are involved in cell proliferation and apoptosis. Chemotherapeutic drugs including cisplatin induce post-transcriptionally endogenous AP-2α, which contributes to chemosensitivity by enhancing therapy-induced apoptosis. microRNAs (miRNAs) miR-200b, miR-200c and miR-429 (miR-200b/200c/429) are up-regulated in endometrial and esophageal cancers, and their overexpression correlates with resistance to cisplatin treatment. Using computational programs, we predicted that the 3′ untranslated region (UTR) of AP-2α gene contains a potential miRNA response element (MRE) for the miR-200b/200c/429 family, and the single nucleotide polymorphism (SNP) site rs1045385 (A or C allele) resided within the predicted MRE. Luciferase assays and Western blot analysis demonstrated that the miR-200b/200c/429 family recognized the MRE in the 3′ UTR of AP-2α gene and negatively regulated the expression of endogenous AP-2α proteins. SNP rs1045385 A>C variation enhanced AP-2α expression by disrupting the binding of the miR-200b/200c/429 family to the 3′ UTR of AP-2α. The effects of the two polymorphic variants on cisplatin sensitivity were determined by clonogenic assay. The overexpression of AP-2α with mutant 3′ UTR (C allele) in the endometrial cancer cell line HEC-1A, which has high levels of endogenous miR-200b/200c/429 and low levels of AP-2α protein, significantly increased cisplatin sensitivity, but overexpression of A allele of AP-2α has no significant effects, compared with mock transfection. We concluded that miR-200b/200c/429 induced cisplatin resistance by repressing AP-2α expression in endometrial cancer cells. The SNP (rs1045385) A>C variation decreased the binding of miR-200b/200c/429 to the 3′ UTR of AP-2α, which upregulated AP-2α protein expression and increased cisplatin sensitivity. Our results suggest that SNP (rs1045385) may be a potential prognostic marker for cisplatin treatment

Cost-effectiveness of an intensive group training protocol compared to physiotherapy guideline care for sub-acute and chronic low back pain: design of a randomised controlled trial with an economic evaluation. [ISRCTN45641649]

BACKGROUND: Low back pain is a common disorder in western industrialised countries and the type of treatments for low back pain vary considerably. METHODS: In a randomised controlled trial the cost-effectiveness and cost-utility of an intensive group training protocol versus physiotherapy guideline care for sub-acute and chronic low back pain patients is evaluated. Patients with back pain for longer than 6 weeks who are referred to physiotherapy care by their general practitioner or medical specialist are included in the study. The intensive group training protocol combines exercise therapy with principles of behavioural therapy ("graded activity") and back school. This training protocol is compared to physiotherapy care according to the recently published Low Back Pain Guidelines of the Royal Dutch College for Physiotherapy. Primary outcome measures are general improvement, pain intensity, functional status, work absenteeism and quality of life. The direct and indirect costs will be assessed using cost diaries. Patients will complete questionnaires at baseline and 6, 13, 26 and 52 weeks after randomisation. DISCUSSION: No trials are yet available that have evaluated the effect of an intensive group training protocol including behavioural principles and back school in a primary physiotherapy care setting and no data on cost-effectiveness and cost-utility are available

The immunosuppressive cytokine interleukin-4 increases the clonogenic potential of prostate stem-like cells by activation of STAT6 signalling

Interleukin-4 plays a critical role in the regulation of immune responses and has been detected at high levels in the tumour microenvironment of cancer patients, where concentrations correlate with the grade of malignancy. In prostate cancer, interleukin-4 has been associated with activation of the androgen receptor, increased proliferation and activation of survival pathways such as Akt and NF-κB. However, its role in therapy resistance has not yet been determined. Here we investigate the influence of interleukin-4 on primary epithelial cells from prostate cancer patients. Our data demonstrate an increase in the clonogenic potential of these cells when cultured in the presence of interleukin-4. In addition, a Phospho-Kinase Array revealed that in contrast to previously published work, signal transducer and activator of transcription6 (STAT6) is the only signalling molecule activated after interleukin-4 treatment. Using the STAT6-specific inhibitor AS1517499 we could confirm the role of STAT6 in increasing colony-forming frequency. However, clonogenic recovery assays revealed that interleukin-4 does not rescue the effects of either irradiation or docetaxel treatment. We therefore propose that although the interleukin-4/STAT6 axis does not appear to be involved in therapy resistance, it does play a crucial role in the colony-forming abilities of the basal cell population in prostate cancer. IL-4 may therefore contribute to disease relapse by providing a niche that is favourable for the clonogenic growth of prostate cancer stem cells

Characterization of an extracellular lipase and its chaperone from Ralstonia eutropha H16

Lipase enzymes catalyze the reversible hydrolysis of triacylglycerol to fatty acids and glycerol at the lipid–water interface. The metabolically versatile Ralstonia eutropha strain H16 is capable of utilizing various molecules containing long carbon chains such as plant oil, organic acids, or Tween as its sole carbon source for growth. Global gene expression analysis revealed an upregulation of two putative lipase genes during growth on trioleate. Through analysis of growth and activity using strains with gene deletions and complementations, the extracellular lipase (encoded by the lipA gene, locus tag H16_A1322) and lipase-specific chaperone (encoded by the lipB gene, locus tag H16_A1323) produced by R. eutropha H16 was identified. Increase in gene dosage of lipA not only resulted in an increase of the extracellular lipase activity, but also reduced the lag phase during growth on palm oil. LipA is a non-specific lipase that can completely hydrolyze triacylglycerol into its corresponding free fatty acids and glycerol. Although LipA is active over a temperature range from 10 °C to 70 °C, it exhibited optimal activity at 50 °C. While R. eutropha H16 prefers a growth pH of 6.8, its extracellular lipase LipA is most active between pH 7 and 8. Cofactors are not required for lipase activity; however, EDTA and EGTA inhibited LipA activity by 83 %. Metal ions Mg[superscript 2+], Ca[superscript 2+], and Mn[superscript 2+] were found to stimulate LipA activity and relieve chelator inhibition. Certain detergents are found to improve solubility of the lipid substrate or increase lipase-lipid aggregation, as a result SDS and Triton X-100 were able to increase lipase activity by 20 % to 500 %. R. eutropha extracellular LipA activity can be hyper-increased, making the overexpression strain a potential candidate for commercial lipase production or in fermentations using plant oils as the sole carbon source.Malaysia-MIT Biotechnology Partnership Programm

Motivational component profiles in university students learning histology: a comparative study between genders and different health science curricula

Background: The students' motivation to learn basic sciences in health science curricula is poorly understood. The purpose of this study was to investigate the influence of different components of motivation (intrinsic motivation, self-determination, self-efficacy and extrinsic -career and grade-motivation) on learning human histology in health science curricula and their relationship with the final performance of the students in histology. Methods: Glynn Science Motivation Questionnaire II was used to compare students' motivation components to learn histology in 367 first-year male and female undergraduate students enrolled in medical, dentistry and pharmacy degree programs. Results: For intrinsic motivation, career motivation and self-efficacy, the highest values corresponded to medical students, whereas dentistry students showed the highest values for self-determination and grade motivation. Genders differences were found for career motivation in medicine, self-efficacy in dentistry, and intrinsic motivation, self-determination and grade motivation in pharmacy. Career motivation and self-efficacy components correlated with final performance in histology of the students corresponding to the three curricula. Conclusions: Our results show that the overall motivational profile for learning histology differs among medical, dentistry and pharmacy students. This finding is potentially useful to foster their learning process, because if they are metacognitively aware of their motivation they will be better equipped to self-regulate their science-learning behavior in histology. This information could be useful for instructors and education policy makers to enhance curricula not only on the cognitive component of learning but also to integrate students' levels and types of motivation into the processes of planning, delivery and evaluation of medical education.This research was supported by the Unidad de Innovación Docente, University of Granada, Spain through grants UGR11-294 and UGR11-303

The Dopamine Augmenter L-DOPA Does Not Affect Positive Mood in Healthy Human Volunteers

Dopamine neurotransmission influences approach toward rewards and reward-related cues. The best cited interpretation of this effect proposes that dopamine mediates the pleasure that commonly accompanies reward. This hypothesis has received support in some animal models and a few studies in humans. However, direct assessments of the effect of transiently increasing dopamine neurotransmission have been largely limited to the use of psychostimulant drugs, which elevate brain levels of multiple neurotransmitters in addition to dopamine. In the present study we tested the effect of more selectively elevating dopamine neurotransmission, as produced by administration of the immediate dopamine precursor, L-DOPA (0, 100/25, 200/50 mg, Sinemet), in healthy human volunteers. Neither dose altered positive mood. The results suggest that dopamine neurotransmission does not directly influence positive mood in humans