Leishmania infantum and Toxoplasma gondii: Mixed infection of macrophages in vitro and in vivo

Although macrophages have a microbicidal role in the immune system they themselves can be infected by pathogens. Often a simultaneous infection by more than one microbe may occur in a single cell. This is the first report of coinfection of macrophages with Toxoplasma gondii and Leishmania infantum, in vitro and in vivo. L. infantum does not cause severe disease in mice but T. gondii, RH strain, is lethal. Cell culture studies using THP-1 macrophages dually infected in vitro revealed that 4.3% harbored both parasites 24 h after infection. When mice were infected with both parasites on the same day 7.3% of the infected cells carried both parasites 7 days later. Yet, if mice were first infected with L. infantum and then with Toxoplasma (5 days post-infection) 18.7% of the macrophages hosted either parasite but concomitant infection could not be found and mice, already harboring L. infantum, survived Toxoplasma’s lethal effect.     

Coupling biomechanics to a cellular level model: an approach to patient-specific image driven multi-scale and multi-physics tumor simulation

Modeling of tumor growth has been performed according to various approaches addressing different biocomplexity levels and spatiotemporal scales. Mathematical treatments range from partial differential equation based diffusion models to rule-based cellular level simulators, aiming at both improving our quantitative understanding of the underlying biological processes and, in the mid- and long term, constructing reliable multi-scale predictive platforms to support patient-individualized treatment planning and optimization. The aim of this paper is to establish a multi-scale and multi-physics approach to tumor modeling taking into account both the cellular and the macroscopic mechanical level. Therefore, an already developed biomodel of clinical tumor growth and response to treatment is self-consistently coupled with a biomechanical model. Results are presented for the free growth case of the imageable component of an initially point-like glioblastoma multiforme tumor. The composite model leads to significant tumor shape corrections that are achieved through the utilization of environmental pressure information and the application of biomechanical principles. Using the ratio of smallest to largest moment of inertia of the tumor material to quantify the effect of our coupled approach, we have found a tumor shape correction of 20% by coupling biomechanics to the cellular simulator as compared to a cellular simulation without preferred growth directions. We conclude that the integration of the two models provides additional morphological insight into realistic tumor growth behavior. Therefore, it might be used for the development of an advanced oncosimulator focusing on tumor types for which morphology plays an important role in surgical and/or radio-therapeutic treatment planning.     

Pre-TCR signaling and CD8 gene bivalent chromatin resolution during thymocyte development

The CD8 gene is silent in CD4(-)CD8(-) double-negative thymocytes, expressed in CD4(+)CD8(+) double-positive cells, and silenced in cells committing to the CD4(+) single-positive (SP) lineage, remaining active in the CD8(+) SP lineage. In this study, we show that the chromatin of the CD8 locus is remodeled in C57BL/6 and B6/J Rag1(-/-) MOM double-negative thymocytes as indicated by DNaseI hypersensitivity and widespread bivalent chromatin marks. Pre-TCR signaling coincides with chromatin bivalency resolution into monovalent activating modifications in double-positive and CD8 SP cells. Shortly after commitment to CD4 SP cell lineage, monovalent repressive characteristics and chromatin inaccessibility are established. Differential binding of Ikaros, NuRD, and heterochromatin protein 1α on the locus during these processes may participate in the complex regulation of CD8.     

Evaluation of the role of the vaccinia virus uracil DNA glycosylase and A20 proteins as intrinsic components of the DNA polymerase holoenzyme

The vaccinia virus DNA polymerase is inherently distributive but acquires processivity by associating with a heterodimeric processivity factor comprised of the viral A20 and D4 proteins. D4 is also an enzymatically active uracil DNA glycosylase (UDG). The presence of an active repair protein as an essential component of the polymerase holoenzyme is a unique feature of the replication machinery. We have shown previously that the A20-UDG complex has a stoichiometry of ～1:1, and our data suggest that A20 serves as a bridge between polymerase and UDG. Here we show that conserved hydrophobic residues in the N' terminus of A20 are important for its binding to UDG. Our data argue against the assembly of D4 into higher order multimers, suggesting that the processivity factor does not form a toroidal ring around the DNA. Instead, we hypothesize that the intrinsic, processive DNA scanning activity of UDG tethers the holoenzyme to the DNA template. The inclusion of UDG as an essential holoenzyme component suggests that replication and base excision repair may be coupled. Here we show that the DNA polymerase can utilize dUTP as a substrate in vitro. Moreover, uracil moieties incorporated into the nascent strand during holoenzyme-mediated DNA synthesis can be excised by the viral UDG present within this holoenzyme, leaving abasic sites. Finally, we show that the polymerase stalls upon encountering an abasic site in the template strand, indicating that, like many replicative polymerases, the poxviral holoenzyme cannot perform translesion synthesis across an abasic site.     

Nitric oxide releasing derivatives of tolfenamic acid with anti-inflammatory activity and safe gastrointestinal profile

Tolfenamic acid esters with nitrooxyalcohols are synthesized. They are anti-inflammatory agents reducing carrageenan rat paw edema, with low gastrointestinal and general toxicity. In vitro, they are nitric oxide donors, inhibitors of lipoxygenase and cyclooxygenases. A two to three carbon chain between carboxylic and nitric ester groups seems optimal for activity.     

Bioavailability of silymarin flavonolignans: drug formulations and biotransformation

Over the past years, great advances have been made on the development of novel delivery systems for bioactive natural compounds, in parallel to their structural modification via chemical, chemo-enzymatic and enzymatic methodologies. These approaches give rise to novel formulations and derivatives that often display advantages over the parental molecule, such as enhanced bioavailability and pharmacological activity, due to improved dissolution and stability. Silymarin components suffer from poor solubility in water and lipid media and their resorption in the intestine is rather limited. Moreover, silybin undergoes intensive Phase II metabolism and is rapidly excreted in bile and urine, leading to low therapeutic efficacy. This work aims to present the current status of available silymarin formulations, and to highlight successful efforts for the biotransformation of its constituent flavonolignans towards the synthesis of novel derivatives. Herein, various pharmaceutical formulations that aim at the bioavailability improvement of these fascinating phytochemicals, i.e., liposomes, phytosomes, self-microemulsifying drug delivery systems, solid dispersions systems, dripping pills, nanosuspensions, floating tablets, and micronization, are reviewed. Silybin (semi)synthetic derivatives prepared by chemical or enzymatic methods, such as fatty acid conjugates, silybin bishemisuccinate, silybin glycosides, silybin sulfates, silybinic acid, and 2,3-dehydrosilybin, are also discussed in detail. Additionally, this work attempts to direct the attention towards the pharmacological implications of optically pure silybin A and silybin B and their biotransformation reactions, both Phase I and II, in relation to bioavailability.