Radiotherapy dose escalation improves tumour control in prostate cancer but with increased toxicity. Boosting focal tumour only may allow dose escalation with acceptable toxicity. Intensity-modulated ...radiotherapy can deliver this, but visualization of the tumour remains limiting. CT or conventional MRI techniques are poor at localizing tumour, but dynamic contrast-enhanced MRI (DCE-MRI) may be superior. 18 patients with prostate cancer had T(2) weighted (T2W) and DCE-MRI prior to prostatectomy. The prostate was sectioned meticulously so as to achieve accurate correlation between imaging and pathology. The accuracy of DCE-MRI for cancer detection was calculated by a pixel-by-pixel correlation of quantitative DCE-MRI parameter maps and pathology. In addition, a radiologist interpreted the DCE-MRI and T2W images. The location of tumour on imaging was compared with histology, and the accuracy of DCE-MRI and T2W images was then compared. Pixel-by-pixel comparison of quantitative parameter maps showed a significant difference between the benign peripheral zone and tumour for the parameters K(trans), v(e) and k(ep). Calculation of areas under the receiver operating characteristic curve showed that the pharmacokinetic parameters were only "fair" discriminators between cancer and benign gland. Interpretation of DCE-MRI and T2W images by a radiologist showed DCE-MRI to be more sensitive than T2W images for tumour localization (50% vs 21%; p = 0.006) and similarly specific (85% vs 81%; p = 0.593). The superior sensitivity of DCE-MRI compared with T2W images, together with its high specificity, is arguably sufficient for its use in guiding radiotherapy boosts in prostate cancer.
To assess the reproducibility of percentage ventilated lung volume (%VV) measurements in healthy volunteers acquired by fluorine (
F)-MRI of inhaled perfluoropropane, implemented at two research ...sites.
In this prospective, ethically approved study, 40 healthy participants were recruited (May 2018-June 2019) to one of two research sites. Participants underwent a single MRI scan session on a 3T scanner, involving periodic inhalation of a 79% perfluoropropane/21% oxygen gas mixture. Each gas inhalation session lasted about 30 seconds, consisting of three deep breaths of gas followed by a breath-hold. Four
F-MR ventilation images were acquired per participant, each separated by approximately 6 minutes. The value of %VV was determined by registering separately acquired
H images to ventilation images before semi-automated image segmentation, performed independently by two observers. Reproducibility of %VV measurements was assessed by components of variance, intraclass correlation coefficients, coefficients of variation (CoV), and the Dice similarity coefficient.
The MRI scans were well tolerated throughout, with no adverse events. There was a high degree of consistency in %VV measurements for each participant (CoV
= 0.43%; CoV
= 0.63%), with overall precision of %VV measurements determined to be within ± 1.7% (95% confidence interval). Interobserver agreement in %VV measurements revealed a high mean Dice similarity coefficient (SD) of 0.97 (0.02), with only minor discrepancies between observers.
We demonstrate good reproducibility of %VV measurements in a group of healthy participants using
F-MRI of inhaled perfluoropropane. Our methods have been successfully implemented across two different study sites, supporting the feasibility of performing larger multicenter clinical studies.
Summary
Background
Portion size influences intake (i.e. the portion size effect PSE), yet determinants of susceptibility to the PSE are unclear.
Objective
We tested whether children who reported an ...episode of loss of control (LOC) eating over the last 3 months would be more susceptible to the PSE and would show differential brain responses to food cues compared with children with no‐LOC.
Methods
Across five sessions, children (n = 47; 7–10 years) consumed four test meals at 100%, 133%, 167% and 200% conditions for portion size and completed a functional magnetic resonance imaging scan while viewing pictures of foods varied by portion size and energy density (ED). Incidence of LOC over the past 3 months was self‐reported. Random coefficient models were tested for differences in the shape of the PSE curve by LOC status. A whole‐brain analysis was conducted to determine response to food cues during the functional magnetic resonance imaging.
Results
Reported LOC (n = 13) compared with no‐LOC (n = 34) was associated with increased susceptibility to the PSE, as evidenced by a positive association with the linear slope (P < 0.005), and negative association with the quadratic slope (P < 0.05) of the intake curve. Children who reported LOC compared with no‐LOC showed increased activation in the left cerebellum to small relative to large portions (P < 0.01) and right cerebellum to High‐ED relative to Low‐ED food cues (P < 0.01).
Conclusion
Children who reported LOC were more susceptible to the PSE and showed alterations in food‐cue processing in the cerebellum, a hindbrain region implicated in satiety signalling.
Controlled dual mode scanning tunneling microscopy (STM) experiments and first-principles simulations show that the tunneling conditions can significantly alter the positive-bias topographic contrast ...of geometrically corrugated titania surfaces such as rutile TiO2(011)-(2×1). Depending on the tip-surface distance, two different contrasts can be reversibly imaged. STM simulations which either include or neglect the tip-electronic structure, carried out at three density functional theory levels of increasing accuracy, allow assignment of both contrasts on the basis of the TiO2(011)-(2×1) structure proposed by Torrelles et al. Phys. Rev. Lett. 101, 185501 (2008). Finally, the mechanisms of contrast formation are elucidated in terms of the subtle balance between the surface geometry and the different vacuum decay lengths of the topmost Ti(3d) and O(2p) states probed by the STM-tip apex.
In a radiotracer study designed to evaluate the fate of metals from fish prey to predator fish, we measured the trophic transfer of 7 trace elements (Am, Cd, Co, Cr, Cs, Mn, Zn) from juvenile ...Mediterranean sea breamSparus auratusto 3 predator species, the teleostsPsetta maximaandSparus auratus, and the elasmobranchScyliorhinus canicula. PreyS. auratuswere labeled by exposure to metal radioisotopes in solution for a period of 3 wk and were then fed to predators, after which the metal retention in the predator was assessed. Mean assimilation efficiencies (AEs) of ingested metals in the predator fishes ranged from 6 to 15% for Am, to 63 to 74% for Cs; significant differences in AEs were noted between species for Co and Mn only. Efflux rate constants (kₑ) of assimilated metal did not differ consistently among predators for any metals. The meankₑ ranged from 0.003 d–1for Mn inS. caniculato 0.02 d–1for Cd and Cs in all 3 species and for Co inS. canicula. Trophic transfer factors (TTF) for each metal were determined in predator fishes to assess the potential for metal biomagnification. TTF, calculated by dividing the product of metal AE and ingestion rate (IR) bykₑ, exceeded 1 only for Mn, Zn and Cs. For most likely scenarios of IR and AE, TTF was <1 for these metals, suggesting that these metals will not biomagnify in piscivorous fishes.
A biokinetic model was used to better understand Ag, Cd and Co concentrations in a population of the clam Macoma balthica in San Francisco Bay. Model parameters included laboratory-derived uptake- ...and loss-rate constants from food and water and field measurements of metal concentrations in food, overlying water and oxidized pore water. Parameters used in modeling were taken from recent studies of metal influx from dissolved sources and metal assimilation from ingested sediment, and from laboratory experiments and field measurements in this study. Assimilation efficiencies from surface sediments ranged from 12 to 22% for Ag, 6 to 13% for Cd and 8 to 20% for Co. Assimilation efficiencies from phytoplankton were higher than metal assimilation efficiencies from sediment, ranging from 36 to 42% for Ag, 47 to 55% for Cd and 27 to 33% for Co. Influx of dissolved metals from overlying water increased with increasing ambient concentration, with uptake-rate constants for Ag (0.34 l g super(-1) d super(-1)) about an order of magnitude higher than for Cd and Co. Influx-rate constants for Ag and Cd from oxidized pore water were comparable to overlying water-rate constants, whereas the rate constant for Co influx from oxidized pore water was 3 times lower than that from overlying water. Efflux rates of all metals out of the clams ranged from 1 to 3% d super(-1). To estimate the potentially bioavailable fraction of particle-bound metals, assumed to be the metal bound to particle surfaces, mean metal concentrations in shale were subtracted from metal concentrations in total sediment digestions. Metal accumulation was modeled for clams that were assumed to be surface deposit-feeding and those that were filter-feeding. By adding uptake from food (surface sediment or phytoplankton) and from dissolved sources (oxidized pore water or overlying water), the modelpredicted ranges of concentrations of Ag, Cd and Co in deposit-feeding clams are shown to be directly comparable to tissue concentrations in field-collected clams from San Francisco Bay. Thus, it appears that the parameters experimentally derived for M. balthica are applicable to field conditions and that the model can account for the major processes governing metal concentrations in these clams. Further, through modeling, ingested sediment was shown to be a major source for Ag and Cd under all realistic environmental conditions, but Co accumulation was principally from the dissolved phase.
In aquatic environments, organisms are exposed to contaminants via direct uptake from water and bytrophic transfer. However, most toxicity tests only examine uptake via the dissolved phase. We ...compared the response of marine and freshwater crustacean zooplankton to silver following dissolved and food exposure. Silver, like other metals, concentrates in aquatic food chains and may exert toxicity. In standard solute exposure toxicity tests, Ag is toxic to zooplankton at concentrations of 400 nM for marine copepods and 100 nM for freshwater cladocerans, concentrations far greater than those in most waters. However, if Ag is accumulated from algal food, reproductive success decreases by >50% when algae are exposed to only 1 nM Ag in copepods and 0.5 nM Ag in cladocerans. These concentrations are within an order of magnitude of those found in contaminated estuaries. Following dietary exposure, decreased egg production and viability occur when tissue Ag concentrations increase three‐ to fourfold to 0.3 ppm in cladocerans and 0.5 ppm in copepods. Assimilated Ag depresses egg production by reducing yolk protein deposition and ovarian development. Our results indicate that ecologically relevant toxicity tests should consider sublethal effects of contaminants obtained from food since these effects cannot be predicted from exposures to only dissolved contaminants.
Biomarkers are needed to improve current diagnosis and surveillance strategies for patients with Barrett's oesophagus (BO) and oesophageal adenocarcinoma (OAC). Macrophage inhibitory cytokine ...1/growth differentiation factor 15 (MIC-1/GDF15) tissue and plasma levels have been shown to predict disease progression in other cancer types and was therefore evaluated in BO/OAC.
One hundred thirty-eight patients were studied: 45 normal oesophagus (NE), 37 BO, 16 BO with low-grade dysplasia (LGD) and 40 OAC.
Median tissue expression of MIC-1/GDF15 mRNA was ⩾25-fold higher in BO and LGD compared to NE (P<0.001); two-fold higher in OAC vs BO (P=0.039); and 47-fold higher in OAC vs NE (P<0.001). Relative MIC-1/GDF15 tissue expression >720 discriminated between the presence of either OAC or LGD vs NE with 94% sensitivity and 71% specificity (ROC AUC 0.86, 95% CI 0.73-0.96; P<0.001). Macrophage inhibitory cytokine 1/growth differentiation factor 15 plasma values were also elevated in patients with OAC vs NE (P<0.001) or BO (P=0.015).High MIC-1/GDF15 plasma levels (⩾1140 pg ml(-1)) were an independent predictor of poor survival for patients with OAC (HR 3.87, 95% CI 1.01-14.75; P=0.047).
Plasma and tissue levels of MIC-1/GDF15 are significantly elevated in patients with BO, LGD and OAC. Plasma MIC-1/GDF15 may have value in diagnosis and monitoring of Barrett's disease.
The lack of a general solution to the governing NavierStokes equations means that there is no fundamental theory of turbulence. In the simpler case of pure quantum turbulence, the tangle of identical ...singly quantized vortices in superuids at T 0 may provide a deeper understanding of turbulence in general. The well-known Kolmogorov theory predicts the energy distribution of turbulence and how it decays. In normal systems the turbulent energy is generally only a small perturbation on the total thermal energy of the supporting medium. In quantum turbulence, however, the energy is accessible. A stationary condensate is necessarily in its ground state with zero enthalpy. Thus quantum turbulence accounts for the entire free energy of the superuid and there are no other contributions. Here, we exploit this property to make the rst direct measurement of the energy released by freely decaying quantum turbulence.
Assimilation efficiencies and physiological turnover-rate constants of six trace elements in four marine bivalves were measured in radiotracer-depuration experiments.
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