Lactobacillus rhamnosus CNCM I-3690 and the commensal bacterium Faecalibacterium prausnitzii A2-165 exhibit similar protective effects to induced barrier hyper-permeability in mice.

Impaired gut barrier function has been reported in a wide range of diseases and syndromes and in some functional gastrointestinal disorders. In addition, there is increasing evidence that suggests the gut microbiota tightly regulates gut barrier function and recent studies demonstrate that probiotic bacteria can enhance barrier integrity. Here, we aimed to investigate the effects of Lactobacillus rhamnosus CNCM I-3690 on intestinal barrier function. In vitro results using a Caco-2 monolayer cells stimulated with TNF-α confirmed the anti-inflammatory nature of the strain CNCM I-3690 and pointed out a putative role for the protection of the epithelial function. Next, we tested the protective effects of L. rhamnosus CNCM I-3690 in a mouse model of increased colonic permeability. Most importantly, we compared its performance to that of the well-known beneficial human commensal bacterium Faecalibacterium prauznitzii A2-165. Increased colonic permeability was normalized by both strains to a similar degree. Modulation of apical tight junction proteins expression was then analyzed to decipher the mechanism underlying this effect. We showed that CNCM I-3690 partially restored the function of the intestinal barrier and increased the levels of tight junction proteins Occludin and E-cadherin. The results indicate L. rhamnosus CNCM I-3690 is as effective as the commensal anti-inflammatory bacterium F. prausnitzii to treat functional barrier abnormalities.

A new graphical user interface for fast construction of computation phantoms and MCNP calculations: application to calibration of in vivo measurement systems.

The paper reports on a new utility for development of computational phantoms for Monte Carlo calculations and data analysis for in vivo measurements of radionuclides deposited in tissues. The individual properties of each worker can be acquired for a rather precise geometric representation of his (her) anatomy, which is particularly important for low energy gamma ray emitting sources such as thorium, uranium, plutonium and other actinides. The software discussed here enables automatic creation of an MCNP input data file based on scanning data. The utility includes segmentation of images obtained with either computed tomography or magnetic resonance imaging by distinguishing tissues according to their signal (brightness) and specification of the source and detector. In addition, a coupling of individual voxels within the tissue is used to reduce the memory demand and to increase the calculational speed. The utility was tested for low energy emitters in plastic and biological tissues as well as for computed tomography and magnetic resonance imaging scanning information.

A new in vitro exposure device for the mobile frequency of 900 MHz.

A wire patch cell has been designed for exposing cell cultures during in vitro experiments studying possible effects of mobile radio telephone. It is based on the wire patch antenna which works at 900 MHz with a highly homogeneous field inside the antenna cavity. The designed cell structure is symmetric and provides a rather homogeneous field distribution in a large area around its centre. Moreover, the exposure cell can irradiate equally up to eight 35 mm Petri dishes at the same time, which enhances the statistical biological studies. To improve the specific absorption rate (SAR) homogeneity inside each sample, each dish is placed into another 50 mm dish. This way, SAR inhomogeneity is always proper for biological studies (below 30%). The main advantage of this new device is that it can provide SAR levels 20 times higher than those induced by classical Crawford transverse electromagnetic (TEM) cell. Moreover, this small open device is easy to construct and fits into an incubator. However, to be used for in vitro, the wire patch cell is a radiating element with the same radiating pattern as a dipole, and thus some absorbing materials are necessary around the system when used for in vitro experiments. Secondly, because of its narrow bandwidth, it is difficult to maintain its working frequency. To overcome this problem, a matching device is integrated into the test cell. In this paper, we present a detailed explanation of the cell behavior and dosimetric assessments for eight 35 mm Petri dishes exposed. Simulations using the Finite Difference Time Domain technique and experimental investigations have been carried out to design the cell at 900 MHz. The numerical dosimetry was validated by dosimetric measurements. These investigations estimated the dosimetric precision at 11%.

Repair of O-alkylpyrimidines in mammalian cells: a present consensus.

Enzymatic repair of the O-alkylpyrimidines (O2- and O4-alkylthymine, O2-alkylcytosine) and alkyl phosphotriesters has been studied in Escherichia coli, and the two proteins involved, a glycosylase (DNA-3-methyladenine glycosylase) and a methyltransferase (DNA-O6-methylguanine:protein-L-cysteine S-methyltransferase, EC 2.1.1.63), have been well characterized. In mammals or mammalian cells treated with carcinogenic alkylating agents, loss of these derivatives has been demonstrated repeatedly. Nevertheless, mammalian repair proteins that are analogous to those from E. coli do not detectably act on these alkyl derivatives. A variety of techniques has been used by many investigators in the United States and Europe, who conclude here that the mode of O-alkylpyrimidine and alkyl phosphotriester repair in mammalian cells differs from that in E. coli. New approaches and methods are needed to characterize these processes at the biochemical and molecular level.