Effect of the local energy distribution of x-ray beams generated through inverse Compton scattering in dual-energy imaging applications.

X-ray sources based on the inverse Compton interaction between a laser and a relativistic electron beam are emerging as a promising compact alternative to synchrotron for the production of intense monochromatic and tunable radiation. The emission characteristics enable several innovative imaging techniques, including dual-energy K-edge subtraction (KES) imaging. The performance of these techniques is optimal in the case of perfectly monochromatic x-ray beams, and the implementation of KES was proven to be very effective with synchrotron radiation. Nonetheless, the features of inverse Compton scattering (ICS) sources make them good candidates for a more compact implementation of KES techniques. The energy and intensity distribution of the emitted radiation is related to the emission direction, which means different beam qualities in different spatial positions. In fact, as the polar angle increases, the average energy decreases, while the local energy bandwidth increases and the emission intensity decreases. The scope of this work is to describe the impact of the local energy distribution variations on KES imaging performance. By means of analytical simulations, the reconstructed signal, signal-to-noise ratio, and background contamination were evaluated as a function of the position of each detector pixel. The results show that KES imaging is possible with ICS x-ray beams, even if the image quality slightly degrades at the detector borders for a fixed collimation angle and, in general, as the beam divergence increases. Finally, an approach for the optimization of specific imaging tasks is proposed by considering the characteristics of a given source.

Head down tilt 15° in experimental intracerebral hemorrhage: a randomized noninferiority safety trial.

BACKGROUND AND PURPOSE: Head down tilt 15° (HDT15°), applied before recanalization, increases collateral flow and improves outcome in experimental ischemic stroke. For its simplicity and low cost, HDT15° holds considerable potential to be developed as an emergency treatment of acute stroke in the prehospital setting, where hemorrhagic stroke is the major mimic of ischemic stroke. In this study, we assessed safety of HDT15° in the acute phase of experimental intracerebral hemorrhage. METHODS: Intracerebral hemorrhage was produced by stereotaxic injection of collagenase in Wistar rats. A randomized noninferiority trial design was used to assign rats to HDT15° or flat position (n = 64). HDT15° was applied for 1 h during the time window of hematoma expansion. The primary outcome was hematoma volume at 24 h. Secondary outcomes were mass effect, mortality, and functional deficit in the main study and acute changes of intracranial pressure, hematoma growth, and cardiorespiratory parameters in separate sets of randomized animals (n = 32). RESULTS: HDT15° achieved the specified criteria of noninferiority for hematoma volume at 24 h. Mass effect, mortality, and functional deficit at 24 h showed no difference in the two groups. HDT15° induced a mild increase in intracranial pressure with respect to the pretreatment values (+2.91 ± 1.76 mmHg). HDT15° had a neutral effect on MRI-based analysis of hematoma growth and cardiorespiratory parameters. CONCLUSIONS: Application of HDT15° in the hyperacute phase of experimental intracerebral hemorrhage does not worsen early outcome. Further research is needed to implement HDT15° as an emergency collateral therapeutic for acute stroke.

Complement C1q-dependent engulfment of alpha-synuclein induces ENS-resident macrophage exhaustion and accelerates Parkinson's-like gut pathology.

Deposition of misfolded α-synuclein (αsyn) in the enteric nervous system (ENS) is found in multiple neurodegenerative diseases. It is hypothesized that ENS synucleinopathy contributes to both the pathogenesis and non-motor morbidity in Parkinson's Disease (PD), but the cellular and molecular mechanisms that shape enteric histopathology and dysfunction are poorly understood. Here, we demonstrate that ENS-resident macrophages, which play a critical role in maintaining ENS homeostasis, initially respond to enteric neuronal αsyn pathology by upregulating machinery for complement-mediated engulfment. Pharmacologic depletion of ENS-macrophages or genetic deletion of C1q enhanced enteric neuropathology. Conversely, C1q deletion ameliorated gut dysfunction, indicating that complement partially mediates αsyn-induced gut dysfunction. Internalization of αsyn led to increased endo-lysosomal stress that resulted in macrophage exhaustion and temporally correlated with the progression of ENS pathology. These novel findings highlight the importance of enteric neuron-macrophage interactions in removing toxic protein aggregates that putatively shape the earliest stages of PD in the periphery.

Comprehensive data set to include interference effects in Monte Carlo models of x-ray coherent scattering inside biological tissues.

Interference effects are included in the x-ray coherent scattering models used in Monte Carlo codes by modifying each material form factor through a proper interference function, which is obtained directly from the measured scattering pattern. This approach is effective for non-biological materials, but it is impractical for biological tissues, due the wide composition variability they can feature. Instead, a given biological sample can be considered as a proper mixture of four basis materials: fat, water, collagen and calcium hydroxyapatite. The sample form factor can then be obtained through a weighted mean of the form factors of the basis materials, which include interference effects. Here, we fully demonstrate the validity of the proposed segmentation method by applying it to 31 biological tissue samples whose form factors are available in the literature. The segmentation, namely the determination of the optimal weight of the basis components, was carried out through a multiple linear regression or, in some cases, by using a controlled trial and error sequence. The form factors of the basis materials were extracted from previous works and elaborated to include more scattering features. In particular, they were interpolated at a denser grid. Furthermore, the data measured separately in wide angle and small angle regimes, for fat and collagen, were merged. In general, a very good agreement was obtained between the original sample and the calculated mixture, being the mean relative difference of their scattering profiles and their attenuation coefficients ∼10%. The segmentation method is fully supported by our extension to the Geant4 model of x-ray coherent scattering, which was used to compare simulated scatter distributions with known experimental data. The developed Geant4 code and a series of molecular form factors, including those of the basis materials, are freely downloadable from a dedicated web repository.

BriXS, a new X-ray inverse Compton source for medical applications.

MariX is a research infrastructure conceived for multi-disciplinary studies, based on a cutting-edge system of combined electron accelerators at the forefront of the world-wide scenario of X-ray sources. The generation of X-rays over a large photon energy range will be enabled by two unique X-ray sources: a Free Electron Laser and an inverse Compton source, called BriXS (Bright compact X-ray Source). The X-ray beam provided by BriXS is expected to have an average energy tunable in the range 20-180 keV and intensities between 1011 and 1013 photon/s within a relative bandwidth ΔE/E=1-10%. These characteristics, together with a very small source size (~20 µm) and a good transverse coherence, will enable a wide range of applications in the bio-medical field. An additional unique feature of BriXS will be the possibility to make a quick switch of the X-ray energy between two values for dual-energy and K-edge subtraction imaging. In this paper, the expected characteristics of BriXS will be presented, with a particular focus on the features of interest to its possible medical applications.

Inverse Compton radiation: a novel x-ray source for K-edge subtraction angiography?

Coronary angiography is clinically used worldwide to diagnose diseases of coronary arteries. Despite its effectiveness, this technique is quite invasive and it is associated with significant risks due to the arterial catheterisation needed to inject the contrast agent. A valid alternative is using the K-edge subtraction (KES) method, which is based on the subtraction of two images acquired at energies bracketing the K-edge of the contrast element. The enhanced sensitivity of KES allows the intravenous injection of the contrast agent, thus reducing the risks of catheterisation. This technique can be effectively implemented by using intense and quasi-monochromatic x-ray beams. Synchrotron radiation has been proven to work well for this purpose, but its cost and size prevent a widespread clinical application. Inverse Compton sources are among the most promising innovative sources of intense and quasi-monochromatic x-rays. These sources are intrinsically more compact than those based on synchrotron radiation. In this work, the potential application of inverse Compton radiation to KES angiography is investigated. To this purpose, after a short review of the physics behind the inverse Compton process, an analytical framework is described. The proposed model is based on the application of the KES algorithm to calculate the SNR of details inside a suitable mathematical phantom. That allowed us to identify the characteristics of an inverse Compton source required for KES imaging. In particular, it was estimated that a photon fluence of 108 ph mm-2 is necessary to detect signals of clinical interest. Novel sources based on inverse Compton promise to achieve this requirement with an acquisition time of few hundreds of ms. This feature, together with compactness, broad two-dimensional radiation field, absence of harmonic contamination and the ability to deliver high photon fluxes also at high energies, makes this kind of sources promising for KES angiography and other diagnostic applications.

The Efficacy and Safety of Lenalidomide plus Rituximab in an Orbital Relapse of Diffuse Large B-Cell Lymphoma.

A 74-year-old male with diffuse large B-cell lymphoma, with an Ann Arbor stage IV-A, was submitted to immune-chemotherapy in 2014, with complete remission of the disease. Two years later, he presented with a left eye swelling leading to exophthalmos and blurred vision. A core biopsy was performed and revealed a local relapse of the disease. He was considered unfit for intensive salvage chemotherapy and was treated with a combination of rituximab and lenalidomide. After six courses of rituximab plus lenalidomide, the patient showed complete remission and was submitted to maintenance therapy with lenalidomide. After 24 months since the start of lenalidomide monotherapy, we did not observe any progression. In this experience, rituximab plus lenalidomide, without radiotherapy, was a safe and effective therapeutic combination in an elderly patient with a localized relapse of DLBCL who was unfit to receive more aggressive therapies.

Changes in subcellular localisation of MI-ER1 alpha, a novel oestrogen receptor-alpha interacting protein, is associated with breast cancer progression.

The oestrogen receptor-alpha (ER alpha) plays a key role in breast development and tumorigenesis and inhibiting its activity remains a prime strategy in the treatment of ER alpha-positive breast cancers. Thus, elucidation of the molecular mechanisms responsible for regulating ER alpha activity may facilitate the design of new, more effective breast cancer therapies. The MI-ER1 alpha is a novel transcriptional repressor that contains an LXXLL motif for interaction with nuclear hormone receptors. We investigated the ability of MI-ER1 alpha to bind to ER alpha in HEK293 and MCF-7 breast carcinoma cells, using co-immunoprecipitation assays. In both cell lines, MI-ER1 alpha interacted with ER alpha in the presence and absence of oestrogen, but the interaction was stronger in the absence of ligand. Functional analysis revealed that overexpression of MI-ER1 alpha in T47D breast carcinoma cells results in inhibition of oestrogen-stimulated anchorage-independent growth, suggesting that MI-ER1 alpha may play a role in regulating breast carcinoma cell proliferation in vivo. To explore this further, we performed an immunohistochemical analysis of normal breast tissue and breast carcinoma; a total of 110 cases were examined in whole tissue sections and 771 cases were analysed in tissue microarrays. No consistent difference in the MI-ER1 alpha expression level between normal breast tissue and breast carcinoma was discernible. However, there was a dramatic shift in the subcellular localisation: nuclear MI-ER1 alpha was detectable in 75% of normal breast samples and in 77% of hyperplasia, but in breast carcinoma, only 51% of DCIS, 25% of ILC and 4% of IDC contained nuclear staining. This shift from nuclear to cytoplasmic localisation of MI-ER1 alpha during breast cancer progression suggests that loss of nuclear MI-ER1 alpha might contribute to the development of invasive breast carcinoma.

Geant4 implementation of inter-atomic interference effect in small-angle coherent X-ray scattering for materials of medical interest.

An extension to Geant4 Monte Carlo code was developed to take into account inter-atomic (molecular) interference effects in X-ray coherent scattering. Based on our previous works, the developed code introduces a set of form factors including interference effects for a selected variety of amorphous materials useful for medical applications, namely various tissues and plastics used to build phantoms. The code is easily upgradable in order to include new materials and offers the possibility to model a generic tissue as a combination of a set of four basic components. A dedicated Geant4 application for the simulation of X-ray diffraction experiments was created to validate the proposed upgrade of Rayleigh scattering model. A preliminary validation of the code obtained through a comparison with EGS4 and an experiment is presented, showing a satisfactory agreement.

X chromosome reactivation in mouse embryonal carcinoma cells.

The embryonal carcinoma cell line, C86S1, carries two X chromosomes, one of which replicates late during S phase of the cell cycle and appears to be genetically inactive. C86S1A1 is a mutant which lacks activity of the X-encoded enzyme, hypoxanthine phosphoribosyltransferase (HPRT). Treatment of C86S1A1 cells with DNA-demethylating agents, such as 5-azacytidine (5AC), resulted in (i) the transient expression in almost all cells of elevated levels of HPRT and three other enzymes encoded by X-linked genes and (ii) the stable expression of HPRT in up to 5 to 20% of surviving cells. Most cells which stably expressed HPRT had two X chromosomes which replicated in early S phase. C86S1A1 cells which had lost the inactive X chromosome did not respond to 5AC. These results suggest that DNA demethylation results in the reactivation of genes on the inactive X chromosome and perhaps in the reactivation of the entire X chromosome. No such reactivation occurred in C86S1A1 cells when the cells were differentiated before exposure to 5AC. Thus, the process of X chromosome inactivation may be a sequential one involving, as a first step, methylation of certain DNA sequences and, as a second step, some other mechanism(s) of transcriptional repression.

Identification of oral risk factors for chronic graft versus host disease in haematological patients who underwent allogeneic haematopoietic stem cell transplantation.

OBJECTIVE: The aim of this prospective observational study was to identify local risk factors for the development of clinical manifestations of oral chronic Graft versus Host Disease (cGvHD) in a cohort of patients affected by haematological malignant diseases who underwent allogeneic haematopoietic stem cell transplantation (HSCT). MATERIALS AND METHODS: In the context of an active collaboration between the Rome Transplant Network of the Hematology and the Oral Pathology Division at "Policlinico Tor Vergata", in Rome, 47 haematological patients were included in this trial based on a systematic dental screening and follow-up protocol. The dental checks were planned 1 month before the transplant procedure while the subsequent follow ups were scheduled on day +100, +180, +365 and + 730 after the transplant. The tool used for the dental checks was a detailed report including all the potential oral features responsible of mechanical, chemical or infective injuries, except for the drugs. RESULTS: Overall, 64% of patients (N=30) did not perform dental hygiene during the screening pre-transplant and 53% (25/47) developed cGvHD with oral involvement. The most part of patients (84%) who experienced oral manifestations of cGvHD during the follow-up period after HSCT did not perform dental hygiene before the transplant procedure. Moreover, the comparison between the "presence" or "absence" of dental hygiene before the allogeneic HSCT showed a statistical significant increasing during the follow-up period in the occurrence of oral lesions due to the cGvHD for patients who lack pre-transplant dental care (p=0.029).On the contrary, the frequency of the other factors such as malocclusions, fractured teeth, incongruous prosthesis, food, smoke, alcol and bad habits, resulted similar between the group with or without typical oral lesions of cGvHD. CONCLUSIONS: The prevention of oral infectious complications provided by primary and secondary dental cares can result in a great benefit for haematological patients who underwent allogeneic HSCT. The combined hematological and dental management represents a clinical need before and after allogeneic HSCT for the removal of inconvenient issues with impact on the short and long-term outcome. Poor dental hygiene seems to be a local risk factor for the development of oral lesions due to cGvHD. However, a larger cohort of patients is necessary to confirm these preliminary data and to evaluate the best preventive and therapeutic oral hygiene protocol in this specific setting.

Neutron Radiation Tolerance of Two Benchmark Thiophene-Based Conjugated Polymers: the Importance of Crystallinity for Organic Avionics.

Aviation and space applications can benefit significantly from lightweight organic electronics, now spanning from displays to logics, because of the vital importance of minimising payload (size and mass). It is thus crucial to assess the damage caused to such materials by cosmic rays and neutrons, which pose a variety of hazards through atomic displacements following neutron-nucleus collisions. Here we report the first study of the neutron radiation tolerance of two poly(thiophene)s-based organic semiconductors: poly(3-hexylthiophene-2,5-diyl), P3HT, and the liquid-crystalline poly(2,5-bis (3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT. We combine spectroscopic investigations with characterisation of intrinsic charge mobility to show that PBTTT exhibits significantly higher tolerance than P3HT. We explain this in terms of a superior chemical, structural and conformational stability of PBTTT, which can be ascribed to its higher crystallinity, in turn induced by a combination of molecular design features. Our approach can be used to develop design strategies for better neutron radiation-tolerant materials, thus paving the way for organic semiconductors to enter avionics and space applications.

Tuning Fullerene Intercalation in a Poly (thiophene) derivative by Controlling the Polymer Degree of Self-Organisation.

Controlling the nanoscale arrangement in polymer-fullerene organic solar cells is of paramount importance to boost the performance of such promising class of photovoltaic diodes. In this work, we use a pseudo-bilayer system made of poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (PBTTT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), to acquire a more complete understanding of the diffusion and intercalation of the fullerene-derivative within the polymer layer. By exploiting morphological and structural characterisation techniques, we observe that if we increase the film solidification time the polymer develops a higher crystalline order, and, as a result, it does not allow fullerene molecules to intercalate between the polymer side-chains. Gaining insight into the detailed fullerene intercalation mechanism is important for the development of organic photovoltaic diodes (PVDs).

Intracellular signalling pathways involved in mesoderm induction by FGF.

We have examined the possible role of two signal transducing mechanisms, tyrosine phosphorylation and activation of protein kinase C (PKC), during fibroblast growth factor (FGF)-induced mesoderm induction in Xenopus. Tyrosine phosphorylation was examined through the use of a monoclonal anti-phosphotyrosine antibody. This antibody was shown to recognize the FGF receptor crosslinked to radioiodinated FGF. We also studied the response of Xenopus ectodermal explants to sodium orthovanadate, a compound that has been shown to elevate intracellular phosphotyrosine levels. Thirty percent of explants cultured in 100 microM vanadate were induced. In addition, vanadate synergized with FGF to give inductions that were more dorsal in nature than either vanadate or FGF alone. The role of PKC was evaluated by measuring PKC activity during mesoderm induction by FGF and by examining the effect of the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) on explants. TPA did not induce mesoderm, however, activation of PKC was detected in FGF-treated explants. Therefore, activation of the PKC pathway alone is not sufficient for mesoderm induction. Simultaneous treatment with TPA and FGF resulted in a significant inhibition of mesoderm induction by FGF, suggesting that activation of PKC could be part of a negative feedback mechanism. In contrast, TPA had no effect on induction by activin A.

Differential nuclear localization of ER1 protein during embryonic development in Xenopus laevis.

The er1 gene is a novel fibroblast growth factor (FGF)-regulated immediate-early gene, first isolated from Xenopus blastulae, that encodes a nuclear protein with potent transcription transactivational activity (Paterno et al., 1997). We report here the expression pattern of the ER1 protein during Xenopus embryonic development. ER1 protein is present in the early embryo but does not begin to appear in the nucleus until the mid-blastula stage. The first cells to show nuclear localization of ER1 are the presumptive mesodermal cells of the stage 8 blastula. ER1 gradually becomes localized to the nucleus of the remaining cells, first in the presumptive ectoderm and finally, in the presumptive endoderm such that by late blastula, all nuclei in the animal hemisphere are stained. By early gastrula, nuclear staining is ubiquitous. During subsequent development, ER1 protein gradually disappears from the nuclei of various tissues. In tailbud stages, ER1 begins to disappear from the nucleus of ectodermally-derived tissues, such as epidermis and brain, while remaining localized in the nucleus of endodermal cells and of mesodermal tissues, such as somites and notochord. In tadpoles, ER1 is no longer detectable in the nucleus of any cells, except for a few endodermal cells. Cytoplasmic staining, on the other hand, is observed in some mesodermal tissues, including somites and muscle cells. Neural tissue is largely unstained except for weak cytoplasmic staining in the eye.

Sequence of a cDNA encoding a mouse cyclin B protein.

We report here the nucleotide sequence of a cDNA encoding a mouse (Mus musculus) cyclin B protein. The deduced protein shows 84%, 66% and 49% similarity with human cyclin, Xenopus cyclin B1 and B2, respectively.

Molecular cloning of human er1 cDNA and its differential expression in breast tumours and tumour-derived cell lines.

We recently cloned and characterized a novel immediate-early gene, called er1, from Xenopus embryos whose expression levels were increased during mesoderm induction by fibroblast growth factor (FGF). We describe here the isolation and expression pattern of the human er1 sequence. Human ER1 and Xenopus ER1 proteins display 91% similarity; the amino acid sequence motifs, including the putative DNA-binding SANT domain, the predicted nuclear localization signals (NLS) and the putative SH3 binding domain share 100% identity. er1 mRNA expression was negligible in all 50 normal human tissues analyzed. Examination of nine breast carcinoma-derived cell lines and eight breast tumour tissue samples by reverse transcription-polymerase chain reaction (RT-PCR) revealed that human er1 was consistently expressed in all tumour cell lines and tumour tissue while remaining undetectable in normal breast cell lines and breast tissue. These data suggest that er1 expression is associated with the neoplastic state in human breast carcinoma.

Nuclear localization signals in the Xenopus FGF embryonic early response 1 protein.

Xenopus early response 1 (XER1) is a fibroblast growth factor-inducible transcription factor whose developmentally regulated nuclear localization is thought to be important in the control of cell differentation during embryonic development [Luchman et al., Mech. Dev. 80 (1999) 111-114]. Analysis of the XER1 amino acid sequence revealed four regions which contain potential nuclear localization sequences (NLSs). Using mutant XER1 proteins and portions of XER1 fused to green fluorescent protein (GFP) transfected into NIH 3T3 cells, we have determined that only one of these, NLS4, located near the carboxy-terminus of XER1, is necessary and sufficient for targeting exclusively to the nucleus. Of the other three predicted NLS sequences, only NLS1, consisting of the sequence (138)RPRRCK(143) was shown to function as a cryptic, weak NLS. NLS4 contains a core region consisting of the sequence (463)RPIKRQRMD(471) which is similar to the core NLS directing the human c-MYC protein to the nucleus. The core sequence is flanked by a predicted cdc2/protein kinase A phosphorylation motif, however mutation of the serine(472) to alanine or aspartic acid had no detectable effect on accumulation of GFP-XER1 fusion proteins in the nucleus, demonstrating that this putative phosphorylation site plays no role in regulating nuclear transport.