The role of metabolic imaging in radiation therapy of prostate cancer.

The goal of this study was to correlate prostatic metabolite concentrations from snap-frozen patient biopsies of recurrent cancer after failed radiation therapy with histopathological findings, including Ki-67 immunohistochemistry and pathologic grade, in order to identify quantitative metabolic biomarkers that predict for residual aggressive versus indolent cancer. A total of 124 snap-frozen transrectal ultrasound (TRUS)-guided biopsies were acquired from 47 men with untreated prostate cancer and from 39 men with a rising prostate-specific antigen and recurrent prostate cancer following radiation therapy. Biopsy tissues with Ki-67 labeling index ≤ 5% were classified as indolent cancer, while biopsy tissues with Ki-67 labeling index > 5% were classified as aggressive cancer. The majority (15 out of 17) of cancers classified as aggressive had a primary Gleason 4 pattern (Gleason score ≥ 4 + 3). The concentrations of choline-containing phospholipid metabolites (PC, GPC, and free Cho) and lactate were significantly elevated in recurrent cancer relative to surrounding benign tissues. There was also a significant increase in [PC] and reduction in [GPC] between untreated and irradiated prostate cancer biopsies. The concentration of the choline-containing phospholipid metabolites was significantly higher in recurrent aggressive (≈ twofold) than in recurrent indolent cancer biopsies, and the receiver operating characteristic (ROC) curve analysis of total choline to creatine ratio (tCho/Cr) demonstrated an accuracy of 95% (confidence interval = 0.88-1.00) for predicting aggressive recurrent disease. The tCho/Cr was significantly higher for identifying recurrent aggressive versus indolent cancer (tCho/Cr = 2.4 ± 0.4 versus 1.5 ± 0.2), suggesting that use of a higher threshold tCho/Cr ratio in future in vivo (1)H MRSI studies could improve the selection and therapeutic planning for patients who would benefit most from salvage focal therapy after failed radiation therapy.

Reproductive and Environmental Drivers of Time and Activity Budgets of Striped Skunks.

The regulation of daily and circannual activity patterns is an important mechanism by which animals may balance energetic requirements associated with both abiotic and biotic variables. Using collar-mounted accelerometers, we assess the relative importance of reproductive stage and environmental conditions on the overall dynamic body acceleration (ODBA) of free-living striped skunks (Mephitis mephitis). We found that activity timing relative to photoperiod varied across seasonal stages for both sexes. Surprisingly, male skunks did not commence activity earlier than females during the mating interval. Moreover, while female skunks began activity before dusk and terminated activity after dawn during mid- through late summer (lactation period), the duration of activity bouts in females during this period was not different from other seasons. Both male and female skunks exhibited high variability and fragmentation in daily activity rhythms except during the lactation period, when females appear to switch to prolonged bouts of nocturnal activity. Overall, ODBA varied by season and sex, with changes in ODBA indicative of seasonal reproductive requirements such as conspecific competition for mates in males and lactation in females. Weather conditions had little effect on skunk activity levels except during the winter season, when snow cover and temperature negatively influenced daily ODBA. Taken together, the activity patterns of striped skunks appear to be primarily driven by seasonal investment in reproduction and secondarily by thermoregulatory constraints during the non-winter months. Our results highlight the importance of considering how environmental and reproductive drivers may interact to affect activity across both the daily and seasonal cycle.

Regulación de la energía en mofetas rayadas ante la reproduccin y el ambiente La regulación de los patrones de actividad diaria y circanual es un mecanismo importante mediante el cual los animales pueden equilibrar los requerimientos energéticos asociados con las variables bióticas y abióticas. Usando acelerómetros montados en collar, evaluamos la importancia relativa de la etapa reproductiva y las condiciones ambientales en la aceleración global dinámica del cuerpo (ODBA, por sus siglas en inglés) de las mofetas rayadas (Mephitis mephitis). Encontramos que el tiempo de actividad en relación con el fotoperíodo varió a lo largo de las etapas estacionales para ambos sexos. Sorprendentemente, las mofetas macho no comenzaron la actividad antes que las hembras durante el intervalo de apareamiento. Además, las mofetas hembra comenzaron la actividad antes del anochecer y terminaron la actividad después del amanecer durante la mitad del verano (período de lactancia), la duración de los episodios de actividad en las hembras durante este período no fue diferente de otras estaciones. Tanto las mofetas macho como las hembra mostraron una alta variabilidad y fragmentación en los ritmos de la actividad diaria, excepto durante el período de lactancia, cuando las hembras parecen cambiar a episodios prolongados de actividad nocturna. En general, la ODBA varió según la temporada y el sexo, con cambios en la ODBA indicativos de los requisitos reproductivos estacionales, como la competencia específica para los machos en los machos y la lactancia en las hembras. Las condiciones climáticas tuvieron poco efecto en los niveles de actividad de la mofeta, excepto durante la temporada de invierno, cuando la capa de nieve y la temperatura influyeron negativamente en la ODBA diaria. Tomados en conjunto, los patrones de actividad de las mofetas rayadas parecen estar impulsados principalmente por la inversión estacional en la reproducción y, en segundo lugar, por las restricciones de termorregulación durante los meses que no son de invierno. Nuestros resultados resaltan la importancia de considerar cómo los impulsores ambientales y reproductivos pueden interactuar para afectar la actividad a lo largo del ciclo diario y estacional. Translated to Spanish by S Hinojosa (hinojosa.silvia@gmail.com).

A unified formalism using effective surface permittivity to study acoustic waves in various anisotropic and piezoelectric multilayers.

A unified formalism is presented that uses the effective surface permittivity (ESP) to study surface acoustic waves (SAW) in layered substrates and guided waves in layered plates. Based on known mathematical tools, such as ordinary differential equation and transfer matrix, a generalized surface impedance (GSI) concept is developed and exploited to investigate the acoustic propagation in various anisotropic and piezoelectric layered structures. The ESP function, originally defined for the surface of a homogeneous and semi-infinite piezoelectric substrate, is extended to both the top surface of and an interface in a layered half space, as well as to either surface of a finite-thickness plate. General ESP expressions for all mentioned configurations are derived in terms of an equivalent GSI matrix. It is shown that, when using the appropriate GSI matrices, the same form of the ESP expressions applies no matter whether the structure is a homogeneous half space alone or coated with a layered plate or a layered plate alone. GSI matrices are explicitly given in terms of the bulk partial mode solutions for a substrate and via the transfer matrix for a plate. Modified GSI matrices for structures consisting of both a plate and a substrate are also specified. Analytical development is fully detailed to suit program implementation. To illustrate its versatility, the formalism is also applied to two-substrate configurations, allowing one to analyze guided waves in a plate sandwiched between and interfacial waves existing along the boundary of two different media. Numerical examples are given to illustrate the spectrum features that the ESP shows for various structures. Deduced ESP expressions allow one to locate directly all piezoelectrically active waves in any structure including at least one piezoelectric layer. Acoustic modes that are not piezoelectrically active and those in non-piezoelectric materials can be also obtained by using the intermediate results, such as derived GSI matrices.