A Semi-parametric Technique for the Quantitative Analysis of Dynamic Contrast-enhanced MR Images Based on Bayesian P-splines

Dynamic Contrast-enhanced Magnetic Resonance Imaging (DCE-MRI) is an important tool for detecting subtle kinetic changes in cancerous tissue. Quantitative analysis of DCE-MRI typically involves the convolution of an arterial input function (AIF) with a nonlinear pharmacokinetic model of the contrast agent concentration. Parameters of the kinetic model are biologically meaningful, but the optimization of the non-linear model has significant computational issues. In practice, convergence of the optimization algorithm is not guaranteed and the accuracy of the model fitting may be compromised. To overcome this problems, this paper proposes a semi-parametric penalized spline smoothing approach, with which the AIF is convolved with a set of B-splines to produce a design matrix using locally adaptive smoothing parameters based on Bayesian penalized spline models (P-splines). It has been shown that kinetic parameter estimation can be obtained from the resulting deconvolved response function, which also includes the onset of contrast enhancement. Detailed validation of the method, both with simulated and in vivo data, is provided

Hypofractionated SBRT versus conventionally fractionated EBRT for prostate cancer: comparison of PSA slope and nadir.

BackgroundPatients with early stage prostate cancer have a variety of curative radiotherapy options, including conventionally-fractionated external beam radiotherapy (CF-EBRT) and hypofractionated stereotactic body radiotherapy (SBRT). Although results of CF-EBRT are well known, the use of SBRT for prostate cancer is a more recent development, and long-term follow-up is not yet available. However, rapid post-treatment PSA decline and low PSA nadir have been linked to improved clinical outcomes. The purpose of this study was to compare the PSA kinetics between CF-EBRT and SBRT in newly diagnosed localized prostate cancer.Materials/methods75 patients with low to low-intermediate risk prostate cancer (T1-T2; GS 3 + 3, PSA < 20 or 3 + 4, PSA < 15) treated without hormones with CF-EBRT (>70.2 Gy, <76 Gy) to the prostate only, were identified from a prospectively collected cohort of patients treated at the University of California, San Francisco (1997-2012). Patients were excluded if they failed therapy by the Phoenix definition or had less than 1 year of follow-up or <3 PSAs. 43 patients who were treated with SBRT to the prostate to 38 Gy in 4 daily fractions also met the same criteria. PSA nadir and rate of change in PSA over time (slope) were calculated from the completion of RT to 1, 2 and 3 years post-RT.ResultsThe median PSA nadir and slope for CF-EBRT was 1.00, 0.72 and 0.60 ng/ml and -0.09, -0.04, -0.02 ng/ml/month, respectively, for durations of 1, 2 and 3 years post RT. Similarly, for SBRT, the median PSA nadirs and slopes were 0.70, 0.40, 0.24 ng and -0.09, -0.06, -0.05 ng/ml/month, respectively. The PSA slope for SBRT was greater than CF-EBRT (p < 0.05) at 2 and 3 years following RT, although similar during the first year. Similarly, PSA nadir was significantly lower for SBRT when compared to EBRT for years 2 and 3 (p < 0.005).ConclusionPatients treated with SBRT experienced a lower PSA nadir and greater rate of decline in PSA 2 and 3 years following completion of RT than with CF-EBRT, consistent with delivery of a higher bioequivalent dose. Although follow-up for SBRT is limited, the improved PSA kinetics over CF-EBRT are promising for improved biochemical control

Raman G and D band in strongly photoexcited carbon nanotubes

We observe clear differences in the spectral shift of the Raman D and G bands when heating double wall carbon nanotubes through intense photon irradiation and by varying the temperature in a thermostat. These spectral differences are attributed to modifications of the defect induced double-resonance Raman process, and are consistent with Stokes–anti-Stokes anomalies observed for single and double wall carbon nanotubes, not present in graphite. We find that the Raman intensity for double wall carbon nanotubes increases superlinearly in the red spectral region and sublinearly in the UV spectral region

MECHANISMS BY WHICH HYPERBARIC OXYGEN THERAPY MAY RESOLVE INFLAMMATION IN CHRONIC WOUNDS

Hyperbaric oxygen (HBO) therapy is the intermittent inhalation of 100% oxygen at a pressure greater than one atmosphere absolute. It is an effective treatment for various inflammatory conditions, including chronic wounds which are characterized by an excessive influx of neutrophils and their prolonged persistence at the wound site. Neutrophil apoptosis and clearance have been shown to be required for resolution of inflammation. The mechanisms by which HBO aids wound healing are well documented, but its effects on cellular inflammatory response are not well understood particularly with respect to neutrophils. The hypothesis presented in this thesis is that increased oxygenation via HBO assists chronic wound healing by enhancing non-inflammatory neutrophil defences and cell death through apoptosis. An investigation was carried out into the effects of HBO on neutrophil antimicrobial function and apoptosis using differentiated HL-60 cells as an in vitro neutrophil model. The data clearly showed that a single HBO treatment for 90 min caused an increase in the oxidative burst activity of neutrophil-like cells as shown by increased NBT staining, superoxide (cytochrome c reduction) and H2O2 production (Kruskal-Wallis, P < 0.05), and phagocytosis of Staphylococcus aureus. HBO treatment displayed a pro-apoptotic effect, enhancing caspase 3/7 activity both in the presence and absence of a TNF-α stimulus (Kruskal-Wallis, P < 0.05) and causing morphological changes (observed using Giemsa and SYBR® Safe staining) associated with apoptosis. Although no consistent pattern was observed, both hyperoxia and pressure alone seemed to contribute to both the increase in antimicrobial activity and the increase in apoptosis induced by HBO in these neutrophil-like cells (Chapters 4 and 5). HBO-enhanced neutrophil clearance by macrophages was investigated using bovine neutrophils and monocyte-derived macrophages (MDMФ). A single 90 min HBO exposure significantly increased the clearance of fresh and 22 h-aged neutrophils by MDMФ (two-way ANOVA, P < 0.05), suggesting an increase in phosphatidylserine (PS) exposure in apoptotic neutrophils after HBO treatment (Chapter 6). Importantly, a long-term repetitive exposure to HBO in patients with chronic wounds caused a significant decrease in the antioxidant enzyme defence system (one-way repeated measures ANOVA, P < 0.05), plasma TNF-α and IL-1β after 30 HBO sessions, with down regulation of expression of the anti-apoptotic factors, NF-B and Bcl-2 (Chapter 7). These findings may go some way towards explaining the effectiveness of HBO treatment not only for chronic wounds but also for other inflammatory conditions that may be affected by this treatment.Iraqi ministry of higher education and scientific researc

Sharing Polarization within Quantum Subspaces

Given an ensemble of n spins, at least some of which are partially polarized, we investigate the sharing of this polarization within a subspace of k spins. We assume that the sharing results in a pseudopure state, characterized by a single purity parameter which we call the bias. As a concrete example we consider ensembles of spin-1/2 nuclei in liquid-state nuclear magnetic resonance (NMR) systems. The shared bias levels are compared with some current entanglement bounds to determine whether the reduced subspaces can give rise to entangled states.Comment: 7 pages, 3 figure