Proton imaging apparatus for protontherapy application

Radiotherapy with protons, due to the physical properties of these particles, offers several advantages for cancer therapy as compared to the traditional radiotherapy with photons. In the clinical use of proton beams, a pCT (proton Computed Tomography) apparatus can contribute to improve the accuracy of the patient positioning and dose distribution calculation. In this paper a pCT apparatus built by the PRIMA (PRoton IMAging) Italian Collaboration will be presented and the preliminary results will be discussed

Plasma-activated medium as an innovative anticancer strategy: Insight into its cellular and molecular impact on in vitro leukemia cells

Cold atmospheric plasma (CAP) has received attention as a potential anticancer strategy. In this study, culture medium was exposed to a microsecond-pulsed dielectric barrier discharge jet to produce plasma-activated medium (PAM). On the T-lymphoblastic cell line, PAM induced apoptosis through the activation of the intrinsic pathway and inhibited the cell-cycle progression. The use of the scavengers N-acetylcysteine or O-phenantroline significantly decreased the PAM proapoptotic activity. The genetic impact of PAM on TK6 cells was assessed, resulting in an increased micronuclei frequency. PAM exhibited cytotoxic effects even on leukemia cells cultivated in hypoxia, which plays a critical role in promoting chemoresistance. PAM was also tested on normal lymphocytes, showing its partial selectivity. Taken together, these results contribute to understand the pharmacotoxicological profile of CAP

PRIMA+: A proton Computed Tomography apparatus

The proton Computed Tomography (pCT) is a medical imaging method, based on the use of proton beams with kinetic energy of the order of 250 MeV, aimed to directly measure the stopping power distribution of tissues thus improving the present accuracy of treatment planning in hadron therapy. A pCT system should be capable to measure tissue electron density with an accuracy better than 1% and a spatial resolution better than 1 mm. The blurring effect due to multiple Coulomb scattering can be mitigated by single proton tracking technique. As a first step towards pCT the PRIMA+ Collaboration built a prototype capable to carry out a single radiography and a tomographic image of a rotating object. This apparatus includes a silicon microstrip tracker to identify the proton trajectory and a YAG:Ce calorimeter to measure the particle residual energy

Development of a Real-Time, Large Area, High Spatial Resolution Particle Tracker Based on Scintillating Fibers

The design of a detector for tracking charged particles is presented together with the characterization techniques developed to extract the main design specifications. The goals for the final detector are to achieve real-time imaging performances, a large detection area, and a high spatial resolution, particularly suitable for medical imaging applications. This paper describes the prototype of the tracker plane, which has a 20 × 20 cm2 sensitive area consisting of two crossed ribbons of 500 μm square scintillating fibers. The information about the hit position extracted real-time tracker in an innovative way, using a reduced number of the read-out channels to obtain a very large detection area but with moderate costs and complexity. The performances of the tracker have been investigated using β sources, cosmic rays, and a 62 MeV proton beam

Pharmacokinetics of acute tryptophan depletion using a gelatin-based protein in male and female Wistar rats

The essential amino acid tryptophan is the precursor of the neurotransmitter serotonin. By depleting the body of tryptophan, brain tryptophan and serotonin levels are temporarily reduced. In this paper, several experiments are described in which dose and treatment effects of acute tryptophan depletion (ATD) using a gelatin-based protein–carbohydrate mixture were studied in male and female Wistar rats. Two or three doses of tryptophan depleting mixture resulted in 65–70% depletion after 2–4 h in males. ATD effects were similar in females, although females may return to baseline levels faster. Treatment effects after four consecutive days of ATD were similar to the effects of 1 day of treatment. Object recognition memory was impaired 2, 4, and 6 h after the first of two doses of ATD, suggesting that the central effects occurred rapidly and continued at least 6 h, in spite of decreasing treatment effects on plasma tryptophan levels at that time point. The method of acute tryptophan depletion described here can be used to study the relationship between serotonin and behaviour in both male and female rats

Effects of Acute Tryptophan Depletion on Brain Serotonin Function and Concentrations of Dopamine and Norepinephrine in C57BL/6J and BALB/cJ Mice

Acute tryptophan depletion (ATD) is a method of lowering brain serotonin (5-HT). Administration of large neutral amino acids (LNAA) limits the transport of endogenous tryptophan (TRP) across the blood brain barrier by competition with other LNAAs and subsequently decreases serotonergic neurotransmission. A recent discussion on the specificity and efficacy of the ATD paradigm for inhibition of central nervous 5-HT has arisen. Moreover, side effects such as vomiting and nausea after intake of amino acids (AA) still limit its use. ATD Moja-De is a revised mixture of AAs which is less nauseating than conventional protocols. It has been used in preliminary clinical studies but its effects on central 5-HT mechanisms and other neurotransmitter systems have not been validated in an animal model. We tested ATD Moja-De (TRP−) in two strains of mice: C57BL/6J, and BALB/cJ, which are reported to have impaired 5-HT synthesis and a more anxious phenotype relative to other strains of mice. ATD Moja-De lowered brain TRP, significantly decreased 5-HT synthesis as indexed by 5-HTP levels after decarboxlyase inhibition, and lowered 5-HT and 5-HIAA in both strains of mice, however more so in C57BL/6J than in BALB/cJ. Dopamine and its metabolites as well as norepinephrine were not affected. A balanced (TRP+) control mixture did not raise 5-HT or 5-HIAA. The present findings suggest that ATD Moja-De effectively and specifically suppresses central serotonergic function. These results also demonstrate a strain- specific effect of ATD Moja-De on anxiety-like behavior

Trophic Shifts of a Generalist Consumer in Response to Resource Pulses

Trophic shifts of generalist consumers can have broad food-web and biodiversity consequences through altered trophic flows and vertical diversity. Previous studies have used trophic shifts as indicators of food-web responses to perturbations, such as species invasion, and spatial or temporal subsidies. Resource pulses, as a form of temporal subsidies, have been found to be quite common among various ecosystems, affecting organisms at multiple trophic levels. Although diet switching of generalist consumers in response to resource pulses is well documented, few studies have examined if the switch involves trophic shifts, and if so, the directions and magnitudes of the shifts. In this study, we used stable carbon and nitrogen isotopes with a Bayesian multi-source mixing model to estimate proportional contributions of three trophic groups (i.e. producer, consumer, and fungus-detritivore) to the diets of the White-footed mouse (Peromyscus leucopus) receiving an artificial seed pulse or a naturally-occurring cicadas pulse. Our results demonstrated that resource pulses can drive trophic shifts in the mice. Specifically, the producer contribution to the mouse diets was increased by 32% with the seed pulse at both sites examined. The consumer contribution to the mouse diets was also increased by 29% with the cicadas pulse in one of the two grids examined. However, the pattern was reversed in the second grid, with a 13% decrease in the consumer contribution with the cicadas pulse. These findings suggest that generalist consumers may play different functional roles in food webs under perturbations of resource pulses. This study provides one of the few highly quantitative descriptions on dietary and trophic shifts of a key consumer in forest food webs, which may help future studies to form specific predictions on changes in trophic interactions following resource pulses