Immunomodulation of the Tumor Microenvironment: Turn Foe Into Friend

Immunotherapy, where the patient's own immune system is exploited to eliminate tumor cells, has become one of the most prominent new cancer treatment options in the last decade. The main hurdle for classical cancer vaccines is the need to identify tumor- and patient specific antigens to include in the vaccine. Therefore, in situ vaccination represents an alternative and promising approach. This type of immunotherapy involves the direct intratumoral administration of different immunomodulatory agents and uses the tumor itself as the source of antigen. The ultimate aim is to convert an immunodormant tumor microenvironment into an immunostimulatory one, enabling the immune system to eradicate all tumor lesions in the body. In this review we will give an overview of different strategies, which can be exploited for the immunomodulation of the tumor microenvironment and their emerging role in the treatment of cancer patients

Construction and model-based analysis of a promoter library for E. coli: an indispensable tool for metabolic engineering

<p>Abstract</p> <p>Background</p> <p>Nowadays, the focus in metabolic engineering research is shifting from massive overexpression and inactivation of genes towards the model-based fine tuning of gene expression. In this context, the construction of a library of synthetic promoters of <it>Escherichia coli </it>as a useful tool for fine tuning gene expression is discussed here.</p> <p>Results</p> <p>A degenerated oligonucleotide sequence that encodes consensus sequences for <it>E. coli </it>promoters separated by spacers of random sequences has been designed and synthesized. This 57 bp long sequence contains 24 conserved, 13 semi-conserved (W, R and D) and 20 random nucleotides. This mixture of DNA fragments was cloned into a promoter probing vector (pVIK165). The ligation mixtures were transformed into competent <it>E. coli </it>MA8 and the resulting clones were screened for GFP activity by measuring the relative fluorescence units; some clones produced high fluorescence intensity, others weak fluorescence intensity. The clones cover a range of promoter activities from 21.79 RFU/OD₆₀₀ml to 7606.83 RFU/OD₆₀₀ml. 57 promoters were sequenced and used for promoter analysis. The present results conclusively show that the postulates, which link promoter strength to anomalies in the -10 box and/or -35 box, and to the length of the spacer, are not generally valid. However, by applying Partial Least Squares regression, a model describing the promoter strength was built and validated.</p> <p>Conclusion</p> <p>For <it>Escherichia coli</it>, the promoter strength can not been linked to anomalies in the -10 box and/or -35 box, and to the length of the spacer. Also a probabilistic approach to relate the promoter sequence to its strength has some drawbacks. However, by applying Partial Least Squares regression, a good correlation was found between promoter sequence and promoter strength. This PLS model can be a useful tool to rationally design a suitable promoter in order to fine tune gene expression.</p

Promoter knock-in: a novel rational method for the fine tuning of genes

<p>Abstract</p> <p>Background</p> <p>Metabolic engineering aims at channeling the metabolic fluxes towards a desired compound. An important strategy to achieve this is the modification of the expression level of specific genes. Several methods for the modification or the replacement of promoters have been proposed, but most of them involve time-consuming screening steps. We describe here a novel optimized method for the insertion of constitutive promoters (referred to as "promoter knock-in") whose strength can be compared with the native promoter by applying a promoter strength predictive (PSP) model.</p> <p>Results</p> <p>Our method was successfully applied to fine tune the <it>ppc </it>gene of <it>Escherichia coli</it>. While developing the promoter knock-in methodology, we showed the importance of conserving the natural leader region containing the ribosome binding site (RBS) of the gene of interest and of eliminating upstream regulatory elements (transcription factor binding sites). The gene expression was down regulated instead of up regulated when the natural RBS was not conserved and when the upstream regulatory elements were eliminated. Next, three different promoter knock-ins were created for the <it>ppc </it>gene selecting three different artificial promoters. The measured constitutive expression of the <it>ppc </it>gene in these knock-ins reflected the relative strength of the different promoters as predicted by the PSP model. The applicability of our PSP model and promoter knock-in methodology was further demonstrated by showing that the constitutivity and the relative levels of expression were independent of the genetic background (comparing wild-type and mutant <it>E. coli </it>strains). No differences were observed during scaling up from shake flask to bioreactor-scale, confirming that the obtained expression was independent of environmental conditions.</p> <p>Conclusion</p> <p>We are proposing a novel methodology for obtaining appropriate levels of expression of genes of interest, based on the prediction of the relative strength of selected synthetic promoters combined with an optimized promoter knock-in strategy. The obtained expression levels are independent of the genetic background and scale conditions. The method constitutes therefore a valuable addition to the genetic toolbox for the metabolic engineering of <it>E. coli</it>.</p

Unilateral sight loss in a 4-year-old girl

For 6 weeks the parents of a 4-year-old girl had noticed a difference between the two eyes of their child. Ophtalmological examination revealed leukocoria. This finding raised clinical suspicion of retinoblastoma. MRI was performed. On T2 weighted images a hypointense mass relative to the vitreous humor was evident. There were several hypointensities compatible with calcifications. An area of retinal detachment was also seen. On T1 weighted images a mildly hyperintense mass relative to vitreous humor was seen. It showed marked contrast enhancement. On diffusion weighted images there was restricted diffusion suggestive for a tumoral lesion. The imaging findings were compatible with a retinoblastoma without transscleral or optic nerve extension. The tumor was complicated by retinal detachment reducing visual potential. The patient was treated with enucleation of the affected eye

Variational assimilation of Lagrangian data in oceanography

We consider the assimilation of Lagrangian data into a primitive equations circulation model of the ocean at basin scale. The Lagrangian data are positions of floats drifting at fixed depth. We aim at reconstructing the four-dimensional space-time circulation of the ocean. This problem is solved using the four-dimensional variational technique and the adjoint method. In this problem the control vector is chosen as being the initial state of the dynamical system. The observed variables, namely the positions of the floats, are expressed as a function of the control vector via a nonlinear observation operator. This method has been implemented and has the ability to reconstruct the main patterns of the oceanic circulation. Moreover it is very robust with respect to increase of time-sampling period of observations. We have run many twin experiments in order to analyze the sensitivity of our method to the number of floats, the time-sampling period and the vertical drift level. We compare also the performances of the Lagrangian method to that of the classical Eulerian one. Finally we study the impact of errors on observations.Comment: 31 page

Leiomyomatosis peritonealis disseminata in a 50-year old woman: imaging findings

Leiomyomatosis peritonealis disseminata (LPD) – or diffuse abdominal leiomyomatosis – is a very rare benign abdominal entity. Only a little more than 100 cases have been reported in the English literature since its first description in 1965. Middle aged female are typically affected and the clinical presentation is rather aspecific. The differential diagnosis between benign LPD and diffuse peritoneal carcinomatosis or abdominal disseminated malignancy represents the crucial diagnostic challenge that can only definitively be made through biopsy and histologic analysis. Multimodal imaging features (ultrasound, CT, MR and PET) of a case of LPD diagnosed in a 50-year old female are presented with review the literature

Neutropenic colitis

Background: A 66-year-old-woman, undergoing chemotherapy for recently diagnosed acute myeloid leukemia developed increasing abdominal pain over a period of several days. Laboratory results showed, apart from severe neutropenia, increasing infection parameters