Stiff polymer in monomer ensemble

We make use of the previously developed formalism for a monomer ensemble and include angular dependence of the segments of the polymer chains thus described. In particular we show how to deal with stiffness when the polymer chain is confined to certain regions. We investigate the stiffness from the perspectives of a differential equation, integral equations, or recursive relations for both continuum and lattice models. Exact analytical solutions are presented for two cases, whereas numerical results are shown for a third case.Comment: 10 pages, including 6 figure

Single-cell resolution imaging of retinal ganglion cell apoptosis in vivo using a cell-penetrating caspase-activatable peptide probe

Peptide probes for imaging retinal ganglion cell (RGC) apoptosis consist of a cell-penetrating peptide targeting moiety and a fluorophore-quencher pair flanking an effector caspase consensus sequence. Using ex vivo fluorescence imaging, we previously validated the capacity of these probes to identify apoptotic RGCs in cell culture and in an in vivo rat model of N-methyl- D-aspartate (NMDA)-induced neurotoxicity. Herein, using TcapQ488, a new probe designed and synthesized for compatibility with clinically-relevant imaging instruments, and real time imaging of a live rat RGC degeneration model, we fully characterized time- and dose-dependent probe activation, signal-to-noise ratios, and probe safety profiles in vivo. Adult rats received intravitreal injections of four NMDA concentrations followed by varying TcapQ488 doses. Fluorescence fundus imaging was performed sequentially in vivo using a confocal scanning laser ophthalmoscope and individual RGCs displaying activated probe were counted and analyzed. Rats also underwent electroretinography following intravitreal injection of probe. In vivo fluorescence fundus imaging revealed distinct single-cell probe activation as an indicator of RGC apoptosis induced by intravitreal NMDA injection that corresponded to the identical cells observed in retinal flat mounts of the same eye. Peak activation of probe in vivo was detected 12 hours post probe injection. Detectable fluorescent RGCs increased with increasing NMDA concentration; sensitivity of detection generally increased with increasing TcapQ488 dose until saturating at 0.387 nmol. Electroretinography following intravitreal injections of TcapQ488 showed no significant difference compared with control injections. We optimized the signal-to-noise ratio of a caspase-activatable cell penetrating peptide probe for quantitative non-invasive detection of RGC apoptosis in vivo. Full characterization of probe performance in this setting creates an important in vivo imaging standard for functional evaluation of future probe analogues and provides a basis for extending this strategy into glaucoma-specific animal models

Identification of DUOX1-dependent redox signaling through protein S-glutathionylation in airway epithelial cells

The NADPH oxidase homolog dual oxidase 1 (DUOX1) plays an important role in innate airway epithelial responses to infection or injury, but the precise molecular mechanisms are incompletely understood and the cellular redox-sensitive targets for DUOX1-derived H2O2 have not been identified. The aim of the present study was to survey the involvement of DUOX1 in cellular redox signaling by protein S-glutathionylation, a major mode of reversible redox signaling. Using human airway epithelial H292 cells and stable transfection with DUOX1-targeted shRNA as well as primary tracheal epithelial cells from either wild-type or DUOX1-deficient mice, DUOX1 was found to be critical in ATP-stimulated transient production of H2O2 and increased protein S-glutathionylation. Using cell pre-labeling with biotin-tagged GSH and analysis of avidin-purified proteins by global proteomics, 61 S-glutathionylated proteins were identified in ATP-stimulated cells compared to 19 in untreated cells. Based on a previously established role of DUOX1 in cell migration, various redox-sensitive proteins with established roles in cytoskeletal dynamics and/or cell migration were evaluated for S-glutathionylation, indicating a critical role for DUOX1 in ATP-stimulated S-glutathionylation of β-actin, peroxiredoxin 1, the non-receptor tyrosine kinase Src, and MAPK phosphatase 1. Overall, our studies demonstrate the importance of DUOX1 in epithelial redox signaling through reversible S-glutathionylation of a range of proteins, including proteins involved in cytoskeletal regulation and MAPK signaling pathways involved in cell migration. © 2014 The Authors

RhoD Inhibits RhoC-ROCK-Dependent Cell Contraction via PAK6.

RhoA-mediated regulation of myosin-II activity in the actin cortex controls the ability of cells to contract and bleb during a variety of cellular processes, including cell migration and division. Cell contraction and blebbing also frequently occur as part of the cytopathic effect seen during many different viral infections. We now demonstrate that the vaccinia virus protein F11, which localizes to the plasma membrane, is required for ROCK-mediated cell contraction from 2 hr post infection. Curiously, F11-induced cell contraction is dependent on RhoC and not RhoA signaling to ROCK. Moreover, RhoC-driven cell contraction depends on the upstream inhibition of RhoD signaling by F11. This inhibition prevents RhoD from regulating its downstream effector Pak6, alleviating the suppression of RhoC by the kinase. Our observations with vaccinia have now demonstrated that RhoD recruits Pak6 to the plasma membrane to antagonize RhoC signaling during cell contraction and blebbing

Oncological considerations of skin-sparing mastectomy

AIM: To review evidence concerning the oncological safety of performing skin-sparing mastectomy (SSM) for invasive breast cancer and ductal carcinoma in situ (DCIS). Furthermore, the evidence concerning RT in relation to SSM and the possibility of nipple preservation was considered. METHODS: Literature review facilitated by Medline and PubMed databases. FINDINGS: Despite the lack of randomised controlled trials, SSM has become an accepted procedure in women undergoing mastectomy and immediate reconstruction for early breast cancer. Compared to non-skin-sparing mastectomy (NSSM), SSM seems to be oncologically safe in patients undergoing mastectomy for invasive tumours smaller than 5 cm, multicentric tumours, DCIS or risk-reduction. However, the technique should be avoided in patients with inflammatory breast cancer or in those with extensive tumour involvement of the skin in view of the high risk of local recurrence. SSM with nipple areola complex (NAC) preservation appears to be oncologically safe, provided the tumour is not close to the nipple and a frozen section protocol for the retro-areolar tissue is followed. Although radiotherapy (RT) does not represent a contraindication to SSM, the latter should be used with caution if postoperative RT is likely, since it detracts from the final cosmetic outcome

Assessment of contractility in intact ventricular cardiomyocytes using the dimensionless ‘Frank–Starling Gain’ index

This paper briefly recapitulates the Frank–Starling law of the heart, reviews approaches to establishing diastolic and systolic force–length behaviour in intact isolated cardiomyocytes, and introduces a dimensionless index called ‘Frank–Starling Gain’, calculated as the ratio of slopes of end-systolic and end-diastolic force–length relations. The benefits and limitations of this index are illustrated on the example of regional differences in Guinea pig intact ventricular cardiomyocyte mechanics. Potential applicability of the Frank–Starling Gain for the comparison of cell contractility changes upon stretch will be discussed in the context of intra- and inter-individual variability of cardiomyocyte properties

Receptor-targeted liposome-peptide-siRNA nanoparticles represent a novel and efficient therapeutic approach to prevent conjunctival fibrosis.

There is increasing evidence that the Myocardin-related transcription factor/Serum response factor (MRTF/SRF) pathway plays a key role in fibroblast activation and that knocking down MRTF can lead to reduced scarring and fibrosis. Here, we have developed a receptor-targeted liposome-peptide-siRNA nanoparticle as a non-viral delivery system for MRTF-B siRNA in conjunctival fibrosis. Using 50 nM siRNA, the MRTF-B gene was efficiently silenced by 76% and 72% with LYR and LER nanoparticles, respectively. The silencing efficiency was low when non-targeting peptides or siRNA alone or liposome-siRNA alone were used. LYR and LER nanoparticles also showed higher silencing efficiency than PEGylated LYR-P and LER-P nanoparticles. The nanoparticles were not cytotoxic using different liposomes, targeting peptides, and 50 nM siRNA. Three-dimensional fibroblast-populated collagen matrices were also used as a functional assay to measure contraction in vitro, and showed that MRTF-B LYR nanoparticles completely blocked matrix contraction after a single transfection treatment. In conclusion, this is the first study to develop and show that receptor-targeted liposome-peptide-siRNA nanoparticles represent an efficient and safe non-viral siRNA delivery system that could be used to prevent fibrosis after glaucoma filtration surgery and other contractile scarring conditions in the eye