Silencing or permanent activation: host-cell responses in models of persistent Chlamydia pneumoniae infection

Chlamydia pneumoniae causes respiratory infections. In chronic diseases associated with Chlamydia, such as arteriosclerosis, C. pneumoniae is present in a persistent form, which might participate in pathogenesis of chronic inflammatory disease. To elucidate how these intracellular bacteria modulate host-cells during persistence, we compared the expression pattern of a range of host genes after short (24 h) and long (up to 7 days) times of chlamydia infection in HeLa-cells. One day post infection, in three cell-culture models of persistence, namely treatment with penicillin or IFN-gamma, or iron-depletion, infection induced the genes of CTGF, IL-6, IL-8, IL-11, LIF, EGR-1 and ETV4 in a similar fashion. However, after a longer time, two modes of host-cell reaction emerged that were dependent on the persistence model used. After IFN-gamma and penicillin treatment chlamydia-induced host-cell gene expression was inhibited, while it stayed upregulated in iron-depletion. Human monocytes/macrophages, in which persistence naturally occurs, were additionally investigated: for several genes, UV-inactivated and viable chlamydia caused long-lasting upregulation. Thus, this study reveals (i) the ability of C. pneumoniae to participate in two putative pathomechanisms of persistence, silencing and permanent activation, which might represent different in vivo situations and (ii) a strong dependence on the mode of persistence induction.     

First multi-locus sequence typing scheme for Arcobacter spp.

Background  

Arcobacter spp. are a common contaminant of food and water, and some species, primarily A. butzleri and A. cryaerophilus, have been isolated increasingly from human diarrheal stool samples. Here, we describe the first Arcobacter multilocus sequence typing (MLST) method for A. butzleri, A. cryaerophilus, A. skirrowii, A. cibarius and A. thereius.     

The chemo enzymatic functionalization of chitosan zeolite particles provides antioxidant and antimicrobial properties

Silicate‐based microporous materials like zeolites are nano enabled particles and used for various applications including pharmaceutical formulations. This study reports on the chemo‐enzymatic functionalization of chitosan‐zeolite particles (CTS‐zeolites) with caffeic acid (CA) and glucose oxidase (GOX) to impart combined antioxidant and antimicrobial properties. CA was grafted on the chitosan moieties by using laccase generating stable particles (zeta potential –36.7 mV) of high antioxidant activity (44% DPPH inhibition). GOX was immobilized both on CTS‐zeolites and on CA modified CTS‐zeolites and creating a hydrogen peroxide generation system continuously and in‐situ producing this oxidative and antimicrobial agent. The system prevented bacterial growth of E. coli and S. aureus over 24 h whereby a steady‐state concentration of around 60 μM hydrogen peroxide in the culture medium was observed. CA and GOX functionalized CTS‐zeolite particles additionally showed combinatorial antioxidant and antimicrobial properties providing a powerful bioactive system for medical applications. These particles proved their suitability for incorporation in bioactive formulations which could be used, inter alia, for topical wound treatments.     

Imaging of non- or very subtle contrast-enhancing malignant gliomas with [¹¹C]-methionine positron emission tomography

In patients with World Health Organization (WHO) grade III glioma with a lack of or minimal (< 1 cm3) magnetic resonance imaging (MRI) contrast enhancement, the volume of the metabolically active part of the tumor was assessed by [11C]-methionine positron emission tomography (MET-PET). Eleven patients with WHO grade III gliomas underwent MET-PET and MRI (contrast-enhanced T1- and T2-weighted images). To calculate the volumes in cubic centimeters, threshold-based volume of interest analyses of the metabolically active tumor (MET uptake index ≥ 1.3), contrast enhancement, and the T2 lesion were performed after coregistration of all images. In all patients, the metabolically active tumor volume was larger than the volume of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) enhancement (20.8 ± 18.8 vs 0.29 ± 0.25 cm3; p < .001). With the exception of one patient, the volumes of contrast enhancement were located within the metabolically active tumor volume. In contrast, in the majority of patients, MET uptake overlapped with the T2 lesion and reached beyond it (in 10 of 12 MRIs/MET-PET scans). The present data suggest that in patients with WHO grade III glioma with minimal or a lack of contrast enhancement, MET-PET delineates metabolically active tumor tissue. These findings support the use of combined PET-MRI with radiolabeled amino acids (eg, MET) for the delineating of the true extent of active tumor in the diagnosis and treatment planning of patients with gliomas.