Direct in vitro comparison of six three-dimensional positive contrast methods for susceptibility marker imaging.

PURPOSE: To compare different techniques for positive contrast imaging of susceptibility markers with MRI for three-dimensional visualization. As several different techniques have been reported, the choice of the suitable method depends on its properties with regard to the amount of positive contrast and the desired background suppression, as well as other imaging constraints needed for a specific application. MATERIALS AND METHODS: Six different positive contrast techniques are investigated for their ability to image at 3 Tesla a single susceptibility marker in vitro. The white marker method (WM), susceptibility gradient mapping (SGM), inversion recovery with on-resonant water suppression (IRON), frequency selective excitation (FSX), fast low flip-angle positive contrast SSFP (FLAPS), and iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) were implemented and investigated. RESULTS: The different methods were compared with respect to the volume of positive contrast, the product of volume and signal intensity, imaging time, and the level of background suppression. Quantitative results are provided, and strengths and weaknesses of the different approaches are discussed. CONCLUSION: The appropriate choice of positive contrast imaging technique depends on the desired level of background suppression, acquisition speed, and robustness against artifacts, for which in vitro comparative data are now available.

The glutathione-deficient mutant pad2-1 accumulates lower amounts of glucosinolates and is more susceptible to the insect herbivore Spodoptera littoralis

Summary Plants often respond to pathogen or insect attack by inducing the synthesis of toxic compounds such as phytoalexins and glucosinolates (GS). The Arabidopsis mutant pad2-1 has reduced levels of the phytoalexin camalexin and is known for its increased susceptibility to fungal and bacterial pathogens. We found that pad2-1 is also more susceptible to the generalist insect Spodoptera littoralis but not to the specialist Pieris brassicae. The PAD2 gene encodes a gamma-glutamylcysteine synthetase that is involved in glutathione (GSH) synthesis, and consequently the pad2-1 mutant contains about 20% of the GSH found in wild-type plants. Lower GSH levels of pad2-1 were correlated with reduced accumulation of the two major indole and aliphatic GSs of Arabidopsis, indolyl-3-methyl-GS and 4-methylsulfinylbutyl-GS, in response to insect feeding. This effect was specific to GSH, was not complemented by treatment of pad2-1 with the strong reducing agent dithiothreitol, and was not observed with the ascorbate-deficient mutant vtc1-1. In contrast to the jasmonate-insensitive mutant coi1-1, expression of insect-regulated and GS biosynthesis genes was not affected in pad2-1. Our data suggest a crucial role for GSH in GS biosynthesis and insect resistance.

Farnesol-induced apoptosis in Candida albicans is mediated by Cdr1-p extrusion and depletion of intracellular glutathione.

Farnesol is a key derivative in the sterol biosynthesis pathway in eukaryotic cells previously identified as a quorum sensing molecule in the human fungal pathogen Candida albicans. Recently, we demonstrated that above threshold concentrations, farnesol is capable of triggering apoptosis in C. albicans. However, the exact mechanism of farnesol cytotoxicity is not fully elucidated. Lipophilic compounds such as farnesol are known to conjugate with glutathione, an antioxidant crucial for cellular detoxification against damaging compounds. Glutathione conjugates act as substrates for ATP-dependent ABC transporters and are extruded from the cell. To that end, this current study was undertaken to validate the hypothesis that farnesol conjugation with intracellular glutathione coupled with Cdr1p-mediated extrusion of glutathione conjugates, results in total glutathione depletion, oxidative stress and ultimately fungal cell death. The combined findings demonstrated a significant decrease in intracellular glutathione levels concomitant with up-regulation of CDR1 and decreased cell viability. However, addition of exogenous reduced glutathione maintained intracellular glutathione levels and enhanced viability. In contrast, farnesol toxicity was decreased in a mutant lacking CDR1, whereas it was increased in a CDR1-overexpressing strain. Further, gene expression studies demonstrated significant up-regulation of the SOD genes, primary enzymes responsible for defense against oxidative stress, with no changes in expression in CDR1. This is the first study describing the involvement of Cdr1p-mediated glutathione efflux as a mechanism preceding the farnesol-induced apoptotic process in C. albicans. Understanding of the mechanisms underlying farnesol-cytotoxicity in C. albicans may lead to the development of this redox-cycling agent as an alternative antifungal agent.

Thrombin-sensitive dual fluorescence imaging and therapeutic agent for detection and treatment of synovial inflammation in murine rheumatoid arthritis.

We have developed a thrombin-sensitive polymeric photosensitizer prodrug (T-PS) to selectively image and eradicate inflammatory lesions in rheumatoid arthritis (RA). Thrombin is a serine protease up-regulated in synovial tissues of rheumatoid arthritis (RA) patients. T-PS consists of a polymeric backbone, to which multiple photosensitizer (PS) units are tethered via short thrombin-cleavable peptide linkers. Fluorescence emission and phototoxicity of the prodrug are efficiently quenched due to the interaction of neighboring photosensitizer units. The prodrug is passively delivered to the inflammation site via the enhanced permeability and retention (EPR) effect. Subsequent site-selective proteolytic cleavage of the peptide linkers restores its photoactivity by increasing the mutual distance between PS. Whole animal imaging in murine collagen-induced arthritis, an experimental model of RA revealed a dose-dependent fluorescence increase in arthritic paws after systemic prodrug injection. In addition, administration of T-PS resulted in much higher fluorescence selectivity for arthritic joints as compared to the free PS. Irradiation of the arthritic joints induced light dose dependent phototoxic effects such as apoptosis, vascular damage and local hemorrhage. Long-term observations showed complete regression of the latter. Irradiated non-arthritic tissues or non-irradiated arthritic tissues showed no histological effects after photodynamic therapy with T-PS. This illustrates that T-PS can localize inflammatory lesions with excellent selectivity and induce apoptosis and vascular shut down after irradiation.

Catalogue des tableaux anciens et modernes... formant le précieux cabinet de M. ***... [de Norzy, agent de change] / [expert] Ferdinand Laneuville

[Vente. Art. 1860-03-16. Paris]

Spatial behavior in groups: an agent-based approach

We present an agent-based model with the aim of studying how macro-level dynamics of spatial distances among interacting individuals in a closed space emerge from micro-level dyadic and local interactions. Our agents moved on a lattice (referred to as a room) using a model implemented in a computer program called P-Space in order to minimize their dissatisfaction, defined as a function of the discrepancy between the real distance and the ideal, or desired, distance between agents. Ideal distances evolved in accordance with the agent's personal and social space, which changed throughout the dynamics of the interactions among the agents. In the first set of simulations we studied the effects of the parameters of the function that generated ideal distances, and in a second set we explored how group macrolevel behavior depended on model parameters and other variables. We learned that certain parameter values yielded consistent patterns in the agents' personal and social spaces, which in turn led to avoidance and approaching behaviors in the agents. We also found that the spatial behavior of the group of agents as a whole was influenced by the values of the model parameters, as well as by other variables such as the number of agents. Our work demonstrates that the bottom-up approach is a useful way of explaining macro-level spatial behavior. The proposed model is also shown to be a powerful tool for simulating the spatial behavior of groups of interacting individuals.

Navigator-gated free-breathing 3D balanced FFE projection renal MRA: Comparison with contrast-enhanced breath-hold 3D MRA in a swine model.

A cardiac-triggered, free-breathing, 3D balanced FFE projection renal MR angiography (MRA) technique with a 2D pencil beam aortic labeling pulse for selective aortic spin tagging was developed. For respiratory motion artifact suppression during free breathing, a prospective real-time navigator was implemented for renal MRA. Images obtained with the new approach were compared with standard contrast-enhanced (CE) 3D breath-hold MRA in seven swine. Signal properties and vessel visualization were analyzed. With the presented technique, high-resolution, high-contrast renal projection MRA with superior vessel length visualization (including a greater visible number of distal branches of the renal arteries) compared to standard breath-hold CE-MRA was obtained. The present results warrant clinical studies in patients with renal artery disease.

Hypermethylation-mediated regulation of CD44 gene expression in human neuroblastoma

The CD44 adhesion receptor is silenced in highly malignant neuroblastomas (NBs) with MYCN amplification. Because its functional expression is associated with decreased tumorigenic properties, CD44 behaves as a tumor suppressor gene in NB and other cancers. Given that the precise mechanisms responsible for CD44 silencing are not elucidated, we investigated whether CD44 expression could be regulated by DNA hypermethylation. The methylation status of CD44 gene promoter and exon 1 regions was analyzed in 12 NB cell lines and 21 clinical samples after bisulfite genomic modification, followed by PCR and single-strand conformation polymorphism analysis and genomic sequencing. The results showed that almost all CD44-negative cell lines displayed hypermethylation in both regions, whereas all CD44-expressing cell lines were unmethylated. These observations correlated with the ability to restore CD44 mRNA and protein expression by treatment of CD44-negative cells with the 5-aza-2'-deoxycytidine demethylating agent. In contrast, no CD44 gene hypermethylation could be detected in 21 NB clinical samples of different stages, irrespective of CD44 expression. Although our results suggest that aberrant methylation of promoter and exon 1 regions is involved in CD44 silencing in NB cell lines, they also indicate that methylation of unidentified regulatory sequences or methylation-independent mechanisms also control the expression of CD44 in primary NB tumors and cell lines. We therefore conclude that CD44 silencing is controlled by complex and tumor cell-specific processes, including gene hypermethylation. Further investigation of other mechanisms and genes involved in CD44 regulation will be needed before demethylation-mediated reactivation of the CD44 gene can be considered as therapeutic strategy for neuroblastoma and perhaps other related cancers.

A pilot study on ocular safety and efficacy of infliximab as an antifibrotic agent after experimental filtration surgery

Purpose To evaluate the safety and efficacy of infliximab as an antifibrotic agent after experimental glaucoma filtration surgery in rabbits. Methods In a randomized, prospective, masked-observer study, 30 New Zealand Albino rabbits underwent glaucoma filtration surgery. The animals were allocated to receive either intraoperative application of infliximab (group A) or mitomycin C (MMC) at a concentration of 0.2mg/ml (group B) or balanced salt solution (BSS, control)(group C). Different infliximab doses, namely 1.0mg, 2.0mg, 3.0mg, 4.0mg, 5.0mg in 0.1ml were applied. Bleb survival and characteristics were evaluated over a 30day period. The animals were killed on postoperative day 15 and 30. Histology of the operated eyes was performed to evaluate and grade the amount of scarring in each group.Cellular density was evaluated in each case. Results Infliximab did not appear to improve the outcome of filtration surgery in this model of glaucoma filtration surgery.There was a significant decrease in cellular density in the MMC group compared to the control group (p=0.0352). There was neither a significant decrease in cellular density between the infliximab group and the control group nor between the infliximab group and the MMC group. Overall there was no difference in terms of fibrosis between the three different groups. There was slightly less inflammation in the infliximab group, but not significant. Conclusions In this study intraoperative application of infliximab does not appear to be superior to the application of MMC or a control with regard to bleb survival and fibrosis. This study however demonstrates that intraoperative application of MMC significantly reduces the cellular density of the filtration bleb.

Molecular diagnostics of gliomas: the clinical perspective.

Significant progress has been made in the molecular diagnostic subtyping of brain tumors, in particular gliomas. In contrast to the classical molecular markers in this field, p53 and epidermal growth factor receptor (EGFR) status, the clinical significance of which has remained controversial, at least three important molecular markers with clinical implications have now been identified: 1p/19q codeletion, O⁶-methylguanine methyltransferase (MGMT) promoter methylation and isocitrate dehydrogenase-1 (IDH1) mutations. All three are favorable prognostic markers. 1p/19q codeletion and IDH1 mutations are also useful to support and extend the histological classification of gliomas since they are strongly linked to oligodendroglial morphology and grade II/III gliomas, as opposed to glioblastoma, respectively. MGMT promoter methylation is the only potentially predictive marker, at least for alkylating agent chemotherapy in glioblastoma. Beyond these classical markers, the increasing repertoire of anti-angiogenic agents that are currently explored within registration trials for gliomas urgently calls for efforts to identify molecular markers that predict the benefit derived from these novel treatments, too.

Systematic assessment of factors influencing preferences of crohn's disease patients in selecting an anti-tumor necrosis factor agent (CHOOSE TNF TRIAL).

BACKGROUND: Infliximab (IFX), adalimumab (ADA), and certolizumab pegol (CZP) have similar efficacy in induction and maintenance of clinical remission in Crohn's disease (CD). Given the comparable nature of these drugs, patient preferences may influence the choice of the product. We aimed to identify factors that may contribute to CD patients' decision in selecting one anti-tumor necrosis factor (TNF) agent over the others. METHODS: A prospective survey was performed among anti-TNF-naïve CD patients. Prior to completion of a questionnaire, patients were provided with a written description of the three anti-TNF agents, focusing on indications, mode of administration, side effects, and scientific evidence of efficacy and safety for each drug. RESULTS: One hundred patients (47 females, mean age 45 ± 16 years, range 19-81) with an ileal, colonic, or ileocolonic (33%, 40%, and 27%, respectively) disease location completed the questionnaire. Based on the information provided, 36% of patients preferred ADA, 28% CZP, and 25% IFX, whereas 11% were undecided. The patients' decision in selecting a specific anti-TNF drug was influenced by the following factors: ease of use (69%), time required for therapy (34%), time interval between application of the drug (31%), scientific evidence for efficacy (19%), and fear of syringes (10%). CONCLUSIONS: The majority of patients preferred anti-TNF medications that were administered by subcutaneous injection rather than by intravenous infusion. Ease of use and time required for therapy were two major factors influencing the patients' selection of a specific anti-TNF drug. Patients' individual preferences should be taken into account when prescribing anti-TNF drugs. (Inflamm Bowel Dis 2012).