The influence of MRI scan position on patients with oropharyngeal cancer undergoing radical radiotherapy

<p>Background: The purpose of this study was to demonstrate how magnetic resonance imaging (MRI) patient position protocols influence registration quality in patients with oropharyngeal cancer undergoing radical radiotherapy and the consequences for gross tumour volume (GTV) definition and radiotherapy planning.</p> <p>Methods and materials: Twenty-two oropharyngeal patients underwent a computed tomography (CT), a diagnostic MRI (MRID) and an MRI in the radiotherapy position within an immobilization mask (MRIRT). Clinicians delineated the GTV on the CT viewing the MRID separately (GTVC); on the CT registered to MRID (GTVD) and on the CT registered to MRIRT (GTVRT). Planning target volumes (PTVs) were denoted similarly. Registration quality was assessed by measuring disparity between structures in the three set-ups. Volumetric modulated arc therapy (VMAT) radiotherapy planning was performed for PTVC, PTVD and PTVRT. To determine the dose received by the reference PTVRT, we optimized for PTVC and PTVD while calculating the dose to PTVRT. Statistical significance was determined using the two-tailed Mann–Whitney or two-tailed paired student t-tests.</p> <p>Results: A significant improvement in registration accuracy was found between CT and MRIRT versus the MRID measuring distances from the centre of structures (geometric mean error of 2.2 mm versus 6.6 mm). The mean GTVC (44.1 cm3) was significantly larger than GTVD (33.7 cm3, p value = 0.027) or GTVRT (30.5 cm3, p value = 0.014). When optimizing the VMAT plans for PTVC and investigating the mean dose to PTVRT neither the dose to 99% (58.8%) nor 95% of the PTV (84.7%) were found to meet the required clinical dose constraints of 90% and 95% respectively. Similarly, when optimizing for PTVD the mean dose to PTVRT did not meet clinical dose constraints for 99% (14.9%) nor 95% of the PTV (66.2%). Only by optimizing for PTVRT were all clinical dose constraints achieved.</p> <p>Conclusions: When oropharyngeal patients MRI scans are performed in the radiotherapy position there are significant improvements in CT-MR image registration, target definition and PTV dose coverage.</p&gt

Unusual chemical composition of a Mexican propolis collected in Quitana Roo, Mexico

Propolis, or bee glue, is a natural resinous hive product collected by honeybees from buds and exudates of various trees and plants. Mixed with beewax and salivary enzymes, it is used to fill in cracks and holes in the hive as well as a chemical weapon against intruders. It is well known that the chemical composition of propolis depends on the flora at the site of collection. The aim of this study was to compare two different propolis batches. The first one collected in France (south-west) and the second one in Quintana Roo, Mexico. The ethanolic extract of the French propolis (EEP) contained mainly polyphenols such as phenolic acids and their esters and flavonoids (poplar type), while the same kind of extract from the Mexican propolis showed only triterpenoids such as α and β-amyrin derivatives. Although the latter composition is quite unusual for a Mexican propolis, α and β-amyrins -and their derivatives- have been reported to occur in the resin of Bursera simaruba,1 a tree that grows in Quintana Roo. Both propolis were evaluated in terms of their biological activity, including antioxidant (DPPH), anti-AGEs, antifungal (Candida albicans and Aspergillus fumigatus), and antibacterial (21 Gram-positive and Gram-negative strains including Staphyloccocus aureus). Whereas French EEP exhibited high antioxidant and anti-AGEs activities,2 as well as very good antifungal (towards C. albicans) and antibacterial (towards S. aureus) activities, Mexican EEP proved to be inactive. These results suggest that the chemical composition of the propolis collected in Quintana Roo is qualitatively and quantitatively of particular importance in the ecological interaction between the bees and the parasites and microorganisms that occur specifically in that region

Unusual chemical composition of a Mexican propolis collected in Quintana Roo, Mexico

Propolis is a resinous natural substance collected by honeybees from buds and exudates of various trees and plants; it is widely accepted that the composition of propolis depends on the phytogeographic characteristics of the site of collection. In this study we have analyzed the chemical composition of a propolis collected in Quintana Roo, Mexico, and evaluated its antioxidant, antifungal and antibacterial activities. Unexpectedly, the chemical analysis showed that the main components of the ethanolic extract of a Mexican propolis appeared to be pentacyclic triterpenoids, such as α and β-amyrin derivatives, and sterols. The crude extract did not show antioxidant activity when tested using the DPPH-reduction assay, and it also proved inactive when tested for antifungal and antibacterial activities using microdilution and agar diffusion assays, respectively. The fact that the presence of both α and β-amyrins and their derivatives have been reported from the resin of Bursera simaruba, one of the plants used by the bees for propolis production in Quintana Roo, Mexico, confirms the relationship that exists between the flora available to bees in a given region and the chemical composition of the propolis that they produce

Unusual chemical composition of a Mexican Propolis collected in Yucatan

Introduction: Propolis, or bee glue, is a natural resinous hive product collected by honeybees from buds and exudates of various trees and plants. Mixed with beewax and salivary enzymes, it is employed to fill cracks and embalm dead invaders in the hive. Several studies about mexican propolis have revealed chemical profiles where cinnamic and phenylpropanoic acid derivatives as well as flavonoids dominated, whereas these extracts exhibited cytotoxic and/or antifungal activities. Research methods: An ethanolic extract of a batch of mexican propolis, collected in the state of Quintana Roo, Mexico, was first analysed by High Performance Liquid Chromatography coupled with Diode Array Detector (HPLC/DAD) but no major components could be detected. Its antioxidant activity was evaluated by 1,1-diPhenyl-2-PicrylHydrazyl (DPPH) assay as well, and its antibacterial (against 21 Gram-positive and Gram-negative strains including Staphyloccocus aureus) and antifungal (against Candida albicans and Aspergillus fumigatus) properties were evaluated through microdilution assays. Then, this extract was fractionated by Flash chromatography. Three of the fractions, containing the major constituents, were analysed by Gas Chromatography coupled with Mass Spectrometry (GC/MS). Results and discussion: This Mexican propolis did not show any antioxidant neither antibacterial nor antifungal activity. The main constituents of this Mexican propolis were identified as triterpenes (amyrenone, amyrin and amyrin-3-acetate) and sterols (fucosterol and sistosterol). This unusual composition associated with a Mexican propolis would thus explain the lack of biological activities. Further investigations will be conducted in order to link this chemical composition with the propolis plant sources

Student Attitude Towards Problem-Based Learning in Management Accounting

This paper examines students’ attitudes towards PBL, an instructional method used for the first time in the accounting programme at the University of Malaya. The findings showed that in general students in the management accounting courses are positive towards PBL. Though male students evaluated PBL more positively than female students, the differences are not statistically significant. On the whole, students who have experienced PBL in other courses, and those in the high academic ability group indicated less favourable attitude towards PBL. Analysis of correlation between examination performance and attitude towards PBL yield weak results, though as a whole those who are more positive towards PBL performed better. Though exploratory, the findings are expected to provide inputs to fine tune the implementation of PBL at the Faculty and contribute to the scarce Malaysian literature. More accounting educators will be exposed to this interactive and constructive approach which has become increasingly more accepted as a student centred teaching and learning instructional method. Finally, the results support arguments for relatively more resources be allocated to problem based learning teaching approaches which are more labour intensive than the conventional lecture based method

Chk1 is essential for chemical carcinogen-induced mouse skin tumorigenesis

Chk1 is a key regulator of DNA damage checkpoint responses and genome stability in eukaryotes. To better understand how checkpoint proficiency relates to cancer development, we investigated the effects of genetic ablation of Chk1 in the mouse skin on tumors induced by chemical carcinogens. We found that homozygous deletion of Chk1 immediately before carcinogen exposure strongly suppressed benign tumor (papilloma) formation, and that the few, small lesions that formed in the ablated skin always retained Chk1 expression. Remarkably, Chk1 deletion rapidly triggered spontaneous cell proliferation, γ-H2AX staining and apoptosis within the hair follicle, a principal site of origin for carcinogen-induced tumors. At later times, the ablated skin was progressively repopulated by non-recombined Chk1-expressing cells and ultimately normal sensitivity to tumor induction was restored when carcinogen treatment was delayed. In marked contrast, papillomas formed normally in Chk1 hemizygous skin but showed an increased propensity to progress to carcinoma. Thus, complete loss of Chk1 is incompatible with epithelial tumorigenesis, whereas partial loss of function (haploinsufficiency) fosters benign malignant tumor progression

Systemic inflammatory response is a predictor of outcome in patients undergoing preoperative chemoradiation for locally advanced rectal cancer

Aim: Current management of locally advanced rectal cancer includes neoadjuvant chemoradiation in selected patients to increase the chance of a tumour-free circumferential resection margin. There is uncertainty over the role of and selection criteria for additional systemic therapy in this group of patients. In this retrospective study we investigate the association between markers of systemic inflammatory response (SIR) and outcome from treatment. Method: One hundred and fifteen patients with locally advanced rectal cancer undergoing preoperative chemoradiation had recording of full blood count parameters including neutrophil/lymphocyte ratio (NLR) and platelet/lymphocyte ratios (PLR). Postoperative surgical margins (R status) and pathological stage were documented. Outcome measures were overall survival (OS), time to local recurrence (TTLR) and disease-free survival (DFS). Cox regression analysis was performed to identify predictors of outcome. Results: Only NLR and R status were significant predictors for all outcome measures on univariate and multivariate analysis. Elevated NLR (≥ 5) was associated with decreased OS, [hazard ratio (HR) and 95% CI, 7.0 (2.6–19.2)], decreased TTLR [HR 3.8 (1.3–11.2)] and shorter DFS [HR 4.1 (1.7–9.8)]. Median survival for patients with an elevated NLR was 18.8 months compared with 54.4 months without an elevated NLR (P < 0.001). Conclusion: In addition to postoperative R-status, an elevated NLR is also a valuable prognostic marker in patients undergoing chemoradiation for locally advanced rectal carcinoma. It is associated with worse OS, TTLR and DFS. An elevated NLR may be a useful additional tool in guiding the decision-making process for adjuvant or neoadjuvant therapies

Determinants of farmers’ adoption of adaptation measures in carbon-intensive agricultural areas: A case study in An Giang province, Vietnam

Globally, agriculture is both a victim and contributor to anthropogenic global warming. While farmers’ climate change perception generally increases, a low-carbon agricultural transition is not always an easy choice. There are numerous studies looking at the constraints hampering farmers’ adoption of adaptation strategies in climate-prone areas worldwide. The extent to which their assertion applies to farmers in carbon-intensive agricultural areas with less experience of climate change effects, however, is not clear and cannot be assumed given the shared social and cultural specificities of the farming population. This paper seeks to address this gap by scrutinizing critical determinants of farmers’ adaptation action in agriculturally rich An Giang province, where climate change impacts are generally less evident. Intense crop cultivation in the province involves the liberal use of fertilizers, crop-residue burning, frequent tilling, and other harmful farming practices that release carbon. Primary data were collected through household surveys (n = 133), field observation, and in-depth interviews (n = 24). A chi-square (χ2) test and a binary logistic regression model was used to analyze the factors influencing farmers’ adaptation decisions. The results indicated that farmers’ adaptation intent and decisions in the research area were significantly determined by market accessibility, uncertainty/instability of existing crops, and extreme weather conditions. These findings shed new light on approaches that are likely to motivate or hamper farmers’ climate-friendly transition in carbon-intensive agricultural hubs. We suggest that adaptive farming initiatives that have the potential to improve marketability and sustainability should be a starting point for mobilizing farmers for a low-carbon farming transition