Evaluation of LiF:Mg,Ti (TLD-100) for Intraoperative Electron Radiation Therapy Quality Assurance

Background

Purpose of the present work was to investigate thermoluminescent dosimeters (TLDs) response to intraoperative electron radiation therapy (IOERT) beams. In an IOERT treatment, a large single radiation dose is delivered with a high dose-per-pulse electron beam (2–12 cGy/pulse) during surgery. To verify and to record the delivered dose, in vivo dosimetry is a mandatory procedure for quality assurance. The TLDs feature many advantages such as a small detector size and close tissue equivalence that make them attractive for IOERT as in vivo dosimeters.

Methods

LiF:Mg,Ti dosimeters (TLD-100) were irradiated with different IOERT electron beam energies (5, 7 and 9 MeV) and with a 6 MV conventional photon beam. For each energy, the TLDs were irradiated in the dose range of 0–10 Gy in step of 2Gy. Regression analysis was performed to establish the response variation of thermoluminescent signals with dose and energy.

Results

The TLD-100 dose-response curves were obtained. In the dose range of 0–10 Gy, the calibration curve was confirmed to be linear for the conventional photon beam. In the same dose region, the quadratic model performs better than the linear model when high dose-per-pulse electron beams were used (F test; p<0.05).

Conclusions

This study demonstrates that the TLD dose response, for doses ≤10Gy, has a parabolic behavior in high dose-per-pulse electron beams. TLD-100 can be useful detectors for IOERT patient dosimetry if a proper calibration is provided.     

Detection of Brucella canis in a dog in Italy

Brucella spp. is a worldwide zoonotic pathogen. Infection by Brucella canis in dogs is endemic in the Southern USA and in Central and South America, but it appears sporadically in other parts of the world, including Europe. Tissue samples from a dog with chronic prostatitis, discospondylitis and locomotor problems were subjected to clinical and laboratory examinations. B. canis was detected by PCR in biological fluids and tissues of the animal, while antibodies to B. canis were found in the serum, providing additional strong evidence for the circulation of B. canis in Italy.     

Short-term effects of thyroid hormones during development: Focus on signal transduction

Extranuclear or nongenomic effects of thyroid hormones are mediated by receptors located at the plasma membrane or inside cells, and are independent of protein synthesis. Recently the αVβ3 integrin was identified as a cell membrane receptor for thyroid hormones, and a wide variety of nongenomic effects have now been shown to be induced through binding of thyroid hormones to this receptor. However, also other thyroid hormone receptors can produce nongenomic effects, including the cytoplasmic TRα and TRβ receptors and probably also a G protein-coupled membrane receptor, and increasing importance is now given to thyroid hormone metabolites like 3,5-diiodothyronine and reverse T₃ that can mimick some nongenomic effects of T₃ and T₄. Signal transduction from the αVβ3 integrin may proceed through at least three independent pathways (protein kinase C, Src or mitogen-activated kinases) but the details are still unknown. Thyroid hormones induce nongenomic effects on at least three important Na⁺-dependent transport systems, the Na⁺/K⁺-ATPase, the Na⁺/H⁺ exchanger, and amino acid transport System A, leading to a mitogenic response in embryo cells; but modulation of the same transport systems may have different roles in other cells and at different developmental stages. It seems that thyroid hormones in many cases can modulate nongenomically the same targets affected by the nuclear receptors through long-term mechanisms. Recent results on nongenomic effects confirm the old theory that the primary role of thyroid hormones is to keep the steady-state level of functioning of the cell, but more and more mechanisms are discovered by which this goal can be achieved.     

Linking Changes in Epithelial Morphogenesis to Cancer Mutations Using Computational Modeling

Most tumors arise from epithelial tissues, such as mammary glands and lobules, and their initiation is associated with the disruption of a finely defined epithelial architecture. Progression from intraductal to invasive tumors is related to genetic mutations that occur at a subcellular level but manifest themselves as functional and morphological changes at the cellular and tissue scales, respectively. Elevated proliferation and loss of epithelial polarization are the two most noticeable changes in cell phenotypes during this process. As a result, many three-dimensional cultures of tumorigenic clones show highly aberrant morphologies when compared to regular epithelial monolayers enclosing the hollow lumen (acini). In order to shed light on phenotypic changes associated with tumor cells, we applied the bio-mechanical IBCell model of normal epithelial morphogenesis quantitatively matched to data acquired from the non-tumorigenic human mammary cell line, MCF10A. We then used a high-throughput simulation study to reveal how modifications in model parameters influence changes in the simulated architecture. Three parameters have been considered in our study, which define cell sensitivity to proliferative, apoptotic and cell-ECM adhesive cues. By mapping experimental morphologies of four MCF10A-derived cell lines carrying different oncogenic mutations onto the model parameter space, we identified changes in cellular processes potentially underlying structural modifications of these mutants. As a case study, we focused on MCF10A cells expressing an oncogenic mutant HER2-YVMA to quantitatively assess changes in cell doubling time, cell apoptotic rate, and cell sensitivity to ECM accumulation when compared to the parental non-tumorigenic cell line. By mapping in vitro mutant morphologies onto in silico ones we have generated a means of linking the morphological and molecular scales via computational modeling. Thus, IBCell in combination with 3D acini cultures can form a computational/experimental platform for suggesting the relationship between the histopathology of neoplastic lesions and their underlying molecular defects.     

Localization of thymulin (FTS-Zn) in mouse thymus. Comparative data using monoclonal antibodies following different plastic embedding procedures

The distribution of thymulin (FTS-Zn) was studied in thymuses from normal mice (OF1) or autoimmune mice (NZB). Thymulin localization was investigated using immunocytochemical techniques on sections of GMA and epon-embedded mouse thymuses. Two monoclonal antibodies were used: anti-synthetic thymulin and anti-intracellular thymulin. In the immunofluorescence assay, GMA sections allowed a more subtle localization of thymulin in the cytoplasm of epithelial cells (with a vacuolar pattern) compared to the epon sections (with a homogeneous fluorescence in the cytoplasm). In both cases, the number of labeled cells was greater in the medullary region than in the cortex of the thymus. At the electron microscopic level, immunolabeling of epon ultrathin sections showed ferritin distributed in some of the epithelial cell vacuoles. The two monoclonal antibodies revealed similar distributions of thymulin in the thymus. The results obtained in this study confirm that the amount of thymulin is greater in the epithelial cells of normal compared to autoimmune thymuses.     

Dissecting drug and vehicle metabolic effects in rats by a metabonomic approach

A combined application of high resolution (1)H NMR spectroscopy and multivariate statistical techniques focused on establishing a consistent statistical approach to metabonomic studies was tested. The data reduction, which is preliminary to the application of multivariate analysis to NMR spectra, was carried out by means of two complementary methods: pure Pattern Recognition (PR) and Assigned Signal Analysis (ASA). The simultaneous use of both approaches allowed us to obtain additional information in the analysis of metabonomic data, compared to the use of PR alone. This additional information consists in the possibility of a biochemical interpretation of the effects induced by treatment with xenobiotics, such as drugs or drug vehicles, on the metabolic networks of the systems under investigation. This approach allowed us to ascertain that a single-dose treatment with ST1959 vehicled by Sesame oil affects the production of hepatic glucose associated to an increment of the amino acid ketogenic process.     

Glycosaminoglycans facilitate procathepsin B activation through disruption of propeptide-mature enzyme interactions

Lysosomal cysteine cathepsin B participates in numerous diverse cellular processes. In acquiring its activity, the proregion, which blocks the substrate-binding site in the proenzyme, needs to be cleaved off. Here we demonstrate that polyanionic polysaccharides, glycosaminoglycans (GAGs), can accelerate the autocatalytic removal of the propeptide and subsequent activation of cathepsin B. We show that naturally occurring GAGs such as chondroitin sulfates and heparin, as well as the synthetic analog dextran sulfate, accelerate the processing in a concentration-dependent manner. Heparin oligosaccharides down to the size of tetrasaccharides were efficient in accelerating the procathepsin B processing, whereas disaccharides were without effect. Further, the ability of the GAGs to accelerate procathepsin B processing was sensitive to increasing NaCl concentrations, indicating that electrostatic interaction between the GAGs and procathepsin B are operative in the accelerating effect. Also the processing of the catalytic procathepsin B mutant by wild type cathepsin B was enhanced in the presence of GAGs, suggesting that GAGs induce a conformational change in procathepsin B, converting it into a better substrate. Site-directed mutagenesis showed that His(28), Lys(39), and Arg(40), located within the procathepsin B propeptide, have significant roles in the acceleration of procathepsin B activation induced by short GAGs. Because procathepsin B and GAGs often co-localize in vivo, we propose that GAGs may play a physiological role in the activation of procathepsin B.     

Specific interactions with intra- and intermolecular G-quadruplex DNA structures by hydrosoluble coronene derivatives: a new class of telomerase inhibitors

In developing G-quadruplex interactive telomerase inhibitors two main features have to be taken into account: the hydrophobic interactions with the G-quartet plane and the electrostatic interactions with the negatively charged phosphates of the four grooves. In this paper, we report the synthesis of four hydrosoluble coronene derivatives, which are characterized by a large hydrophobic aromatic core and four orthogonal hydrophilic side chains. We have studied their ability to induce both inter- and intramolecular G-quadruplex structures and found a significant selectivity of all the coronene derivatives for the intramolecular G-quadruplex. The efficiency in inhibiting human telomerase has been evaluated in a cell-free system and the experimental results correlate with the relative affinities of these compounds for the G-quadruplex monomeric structure, as derived by molecular modelling simulations. Thus, the coronene derivatives can be considered as a new class of telomerase inhibitors, although further investigations are surely necessary to fully exploit their features.     

Prospective study of BKV nephropathy in 117 renal transplant recipients

Nephropathy caused by poliomavirus (BKVAN) in transplant recipients is responsible for the loss of the transplanted organ. In this study we suggest a non-invasive diagnostic protocol for the early identification of BKVAN during follow-up treatments. In 117 kidney transplant recipients follow-up was performed every three months during a two year period after transplantation and a positive screening result was confirmed and assessed by quantitative assays (BKV DNA load in plasma and urine). The definitive diagnosis of BKV requires allograft biopsy. Of the 117 patients 4 had BKVAN (3.4%), and the consequential reduction of immunosuppression improved kidney function and plasma clearance of the virus was achieved.