Search

Abstract Background Highly pathogenic mycobacteria like Mycobacterium tuberculosis are characterised by their slow growth and their ability to reside and multiply in the very hostile phagosomal environment and a correlation between the growth rate of mycobacteria and their pathogenicity has been hypothesised. Here, porin genes from M. fortuitum were cloned and characterised to address their impact on the growth rate of fast-growing and pathogenic mycobacteria. Results Two genes encoding porins orthologous to MspA from M. smegmatis, porM1 and porM2, were cloned from M. fortuitum strains, which were originally isolated from human patients. Both porin genes were at least partially able to complement the mutations of a M. smegmatis mutant strain lacking the genes mspA and mspC with respect to the growth rate. PorM1 and porM2 were present in different strains of M. fortuitum including the type strain. Comparative expression analysis of porM genes revealed divergent porin expression among analysed M. fortuitum strains. Repression of the expression of porins by antisense technique decreased the growth rates of different M. fortuitum. The effects of over-expression of porM1 as well as porM2 varied depending on the strain and the concentration of antibiotic added to the medium and indicated that PorM1 and PorM2 enhance the growth of M. fortuitum strains, but also the diffusion of the antibiotic kanamycin into the cells. Conclusion This study demonstrates the important role of porin expression in growth as well as antibiotic susceptibility of the opportunistic bacterium M. fortuitum.

Introduction: The relationships between histopathology and imaging remain elusive, and investigating the underlying reasons for tumor microstructure leading to an imaging phenotype is of clinical importance. In the present study, a cross-sectional guided biopsy specimen was used to correlate prebioptic magnetic resonance imaging (MRI) with immunohistochemical staining of the histopathologic specimen using precise spatial biopsy localization., Methods: Twenty-seven patients with mass-forming cholangiocarcinoma (CCA) were included in the present analysis. All patients were imaged with a 1.5 T clinical scanner at least 1 month prior to biopsy. The contrast-enhanced dynamic sequences were analyzed with quantified signal intensities. The bioptic specimens were obtained by cross-sectional guided biopsy and further analyzed for cell density, proliferation index (Ki67), tumor-infiltrating lymphocytes, tumor-stroma ratio (TSR), and collagen., Results: There were no statistically significant correlations between MRI signal intensities and cell count, TSR, Ki67 index, and CD45 count. Only a moderate correlation was observed between relative signal intensities of the venous phase and the collagen-stained area (r = 0.40, p = 0.04)., Conclusion: DCE-MRI is not associated with histopathological features in CCA. The complex interactions of tumor and tumor microenvironment are not reflected in the MRI phenotype., (© 2024 S. Karger AG, Basel.)