20 research outputs found
Active transforming growth factor-β is associated with phenotypic changes in granulomas after drug treatment in pulmonary tuberculosis
Background: Tuberculosis (TB) chemotherapy clears bacterial burden in the lungs of patients and allows the tuberculous lesions to heal through a fibrotic process. The healing process leaves pulmonary scar tissue that can impair lung function. The goal of this study was to identify fibrotic mediators as a stepping-stone to begin exploring mechanisms of tissue repair in TB. Methods: Hematoxylin and eosin staining and Masson's trichrome stain were utilized to determine levels of collagenization in tuberculous granulomas from non-human primates. Immunohistochemistry was then employed to further interrogate these granulomas for markers associated with fibrogenesis, including transforming growth factor-β (TGFβ), α-smooth muscle actin (αSMA), phosphorylated SMAD-2/3, and CD163. These markers were compared across states of drug treatment using one-way ANOVA, and Pearson's test was used to determine the association of these markers with one another. Results: TGFβ and αSMA were present in granulomas from primates with active TB disease. These molecules were reduced in abundance after TB chemotherapy. Phosphorylated SMAD-2/3, a signaling intermediate of TGFβ, was observed in greater amounts after 1 month of drug treatment than in active disease, suggesting that this particular pathway is blocked in active disease. Collagen production during tissue repair is strongly associated with TGFβ in this model, but not with CD163+ macrophages. Conclusions: Tissue repair and fibrosis in TB that occurs during drug treatment is associated with active TGFβ that is produced during active disease. Further work will identify mechanisms of fibrosis and work towards mitigating lung impairment with treatments that target those mechanisms
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Clearing transcription barriers to replication
Bacterial genome duplication and transcription require simultaneous access to the same DNA template. Conflicts between the replisome and transcription machinery can lead to interruption of DNA replication and loss of genome stability. Pausing, stalling and backtracking of transcribing RNA polymerases
add to this problem and present barriers to replisomes. Accessory helicases promote forkmovement through nucleoprotein barriers and exist in viruses, bacteria and eukaryotes. Here, we show that stalled Escherichia coli transcription elongation complexes block reconstituted replisomes. This physiologically relevant block can be alleviated by the accessory helicase Rep or UvrD, resulting in the formation of fulllength replication products. Accessory helicase action during replication-transcription collisions therefore promotes continued replication without leaving gaps in the DNA. In contrast, DinG does not promote replisome movement through stalled transcription complexes in vitro. However, our data demonstrate that DinG operates indirectly in vivo to reduce conflicts between replication and transcription. These results suggest that Rep and UvrD helicases operate on DNA at the replication fork whereas DinG helicase acts via a different mechanism.UK Biotechnology and Biological Sciences Research Council (BBSRC) [BB/I001859/2, BB/N014863/1 to P.M., BB/K015729/1, BB/N014995/1 to C.J.R. and BB/I003142/1 to N.J.S. and M.S.D.]. Funding for open access charge: York Open Access Fund
Single-molecule live cell imaging of Rep reveals the dynamic interplay between an accessory replicative helicase and the replisome
Silica-attached molecular receptor complexes for benzoates and naphthoates
A series of cyclen (1,4,7,10-tetraazacyclododecane) derived molecular receptors for aromatic oxoanions, that are activated by complexation with Cd(II), have been covalently linked to 3-(glycidoxy)propyl-functionalised silica gel (70–230 mesh). These immobilised receptor complexes are highly effective for the sequestration of o-hydroxybenzoates and 2-naphthoate from aqueous solution, achieving a >80% saturation level by stirring the material in the aqueous solution for 1 h at pH 7.00 and 298 K. Examination of the uptake levels of a variety of different benzoates and naphthoates suggests that the retention mechanism involves a combination of classical hydrogen bonding and non-classical, water mediated, O–H···π hydrogen bonding. Contrary to expectations, attachment of hydroxy terminated polyether chains to the periphery of the receptor complex diminished the level of uptake.Jozef A. Z. Hodyl, Stephen F. Lincoln and Kevin P. Wainwrigh