Pathological Outcome in Men with Prostate Cancer Suitable for Active Surveillance after Radical Prostatectomy

Background: Active surveillance (AS) as a treatment option for low risk prostate cancer is gaining recognition. We evaluate the validity of the AS protocol in our patient population, by defining the risk of undergrading and understaging in their pathology. We also aim to determine more accurate inclusion criteria, in order to improve the prediction of early low risk prostate cancer. Materials and Methods: Data was taken from our institutional prostate cancer registry for all men who underwent radical prostatectomy (RP) between Jan 2000 and June 2009. We determined if any of the patients would have met the University of Toronto's (UoT) AS inclusion criteria and examined their post-operative pathology. The primary end-point was pathological upgrading and upstaging. The individual inclusion factors i.e. preoperative PSA, were tested for statistical significance and better cutoffs. Univariate, multivariate and ROC curves were used in the statistical analysis. Results: 216 RPs were performed between January 2000 and June 2009. We identified 79 men who fulfilled the UoT AS criteria. 35% of patients had a Gleason score upgrade from biopsy to surgery, and 21.5% of patients had an upstage to T3 disease. Overall, 34 (43%) patients had an unfavourable change in the grade and/or stage of their prostate cancer. Conclusions: There is a significant risk of undergrading and understaging with the current criteria used for AS. There is a need to identify more discriminative AS criteria before it can be offered as an option to patients with clinically early prostate cancer

Dose rate dependence of electrical characteristics of lead zirconate titanate capacitors

The influence of gamma-radiation dose rate on the electrical properties of lead zirconate titanate capacitors was investigated. More severe degradations in dielectric constant, coercive field, remanent polarization and capacitance-voltage (C-V) curves occurred with increasing radiation dose at lower dose rates. The electrical properties exhibited distinct radiation dose rate dependence and the worst-case degradation occurred at the lowest dose rate. The radiation-induced degradation of parameters such as the coercive field drift and distortion of the C-V curve can be recovered partly through post-irradiation annealing

Modern hexaploid wheat differs from diploid and tetraploid ancestors in the importance of stress tolerance versus stress avoidance

Combined high temperature and weak radiation stress negatively influences wheat production. However, related eco-physiological mechanisms across wheat species of different genetic backgrounds are not well documented. A pot-culture experiment was conducted in growth chambers to analyse the prevailing strategies of wheat genotypes with different ploidy levels under combined high temperature and weak radiation (30 degrees C-25 degrees C, 200 mu molm(-2) s(-1) photosynthetically active radiation (PAR)) stress compared with normal growth conditions (20 degrees C-15 degrees C; 400 mu molm(-2) s(-1) PAR). The diploid and tetraploid wheat genotypes showed better avoidance ability to high temperature and weak radiation stress than the hexaploids. These diploids and tetraploids produced high vegetative biomass under control conditions but this was reduced substantially under the stress. The adaptive response to avoid the stress was a strong reduction in vegetative organs, mainly leaf area. Consequently, these genotypes produced lower yields. By contrast, modern hexaploid wheat varieties displayed a stronger tolerance to the stress and produced higher yields through greater green leaf area, higher relative leaf water content, and higher proline and soluble sugar contents. The relative importance of these tolerance and avoidance strategies was estimated to account for 60% and 22%, respectively, of the variations in grain yield. Our study demonstrated that modern hexaploid wheat has acquired a greater proportion of tolerance rather than avoidance strategy in response to high temperature and weak radiation stress

Morphological and physiological responses of different wheat genotypes to chilling stress: a cue to explain yield loss

BACKGROUNDThe eco-physiological mechanism of wheat yield loss resulting from chilling stress is a fundamental scientific issue. However, previous studies have focused on hexaploid wheats, and few studies on the morphological and physiological plasticity of wheat plants. Six different wheat genotypes were tested under chilling stress to investigate the physio-morphological parameters as well as the loss of grain yield in growth chambers. RESULTSChilling stress resulted in significant loss in grain yield in all genotypes. Under chilling stress, diploid wheats generated zero harvest, and tetraploid genotypes also suffered from a pronounced loss in grain yield, compared with the control group. In contrast, hexaploid genotypes acquired relatively high maintenance rate of grain yield among three species. CONCLUSIONSDiploid and tetraploid wheat genotypes maintained relatively large leaf area and high photosynthetic rates, but they were subjected to significant declines in vascular bundle number and productive tillers as a consequence of the inhibition by sink growth under chilling stress. The hexaploid wheats were found to have relatively low leaf area and photosynthetic rates. These genotypes also stored more soluble carbohydrates and exhibited stronger sink enhancement, ensuring the translocation and redistribution of assimilates. Our findings provided a new theoretical understanding of yield stabilization in the domestication process of wheat genotypes under chilling stress. (c) 2017 Her Majesty the Queen in Right of Canada. Journal of The Science of Food and Agriculture (c) 2017 Society of Chemical Industr