Segmentation in cohesive systems constrained by elastic environments

The complexity of fracture-induced segmentation in elastically constrained cohesive (fragile) systems originates from the presence of competing interactions. The role of discreteness in such phenomena is of interest in a variety of fields, from hierarchical self-assembly to developmental morphogenesis. In this paper, we study the analytically solvable example of segmentation in a breakable mass-spring chain elastically linked to a deformable lattice structure. We explicitly construct the complete set of local minima of the energy in this prototypical problem and identify among them the states corresponding to the global energy minima. We show that, even in the continuum limit, the dependence of the segmentation topology on the stretching/pre-stress parameter in this problem takes the form of a devil's type staircase. The peculiar nature of this staircase, characterized by locking in rational microstructures, is of particular importance for biological applications, where its structure may serve as an explanation of the robustness of stress-driven segmentation.This article is part of the themed issue 'Patterning through instabilities in complex media: theory and applications.'

Funding for cerebral palsy research in Australia, 2000-2015: an observational study

OBJECTIVES

To examine the funding for cerebral palsy (CP) research in Australia, as compared with the National Institutes of Health (NIH).

DESIGN

Observational study.

SETTING

For Australia, philanthropic funding from Cerebral Palsy Alliance Research Foundation (CPARF) (2005-2015) was compared with National Health and Medical Research Council (NHMRC, 2000-2015) and Australian Research Council (ARC, 2004-2015) and CPARF and NHMRC funding were compared with NIH funding (USA).

PARTICIPANTS

Cerebral Palsy researchers funded by CPARF, NHMRC or NIH.

RESULTS

Over 10 years, total CPARF philanthropic funding was $21.9 million, including people, infrastructure, strategic and project support. As competitive grants, CPARF funded $11.1 million, NHMRC funded $53.5 million and Australian Research Council funded $1.5 million. CPARF, NHMRC and NIH funding has increased in real terms, but only the NIH statistically significantly increased in real terms (mean annual increase US$4.9 million per year, 95% CI 3.6 to 6.2, p<0.001). The NHMRC budget allocated to CP research remained steady over time at 0.5%. A network analysis indicated the relatively small number of CP researchers in Australia is mostly connected through CPARF or NHMRC funding.

CONCLUSIONS

Funding for CP research from the Australian government schemes has stabilised and CP researchers rely on philanthropic funding to fill this gap. In comparison, the NIH is funding a larger number of CP researchers and their funding pattern is consistently increasing.

In silico analysis of the transportome in human pancreatic ductal adenocarcinoma

The altered expression and/or activity of ion channels and transporters (transportome) have been associated with malignant behavior of cancer cells and were proposed to be a hallmark of cancer. However, the impact of altered transportome in epithelial cancers, such as pancreatic ductal adenocarcinoma (PDAC), as well as its pathophysiological consequences, still remains unclear. Here, we report the in silico analysis of 840 transportome genes in PDAC patients' tissues. Our study was focused on the transportome changes and their correlation with functional and behavioral responses in PDAC tumor and stromal compartments. The dysregulated gene expression datasets were filtered using a cut-off of fold-change values ≤-2 or ≥2 (adjusted p value ≤0.05). The dysregulated transportome genes were clearly associated with impaired physiological secretory mechanisms and/or pH regulation, control of cell volume, and cell polarity. Additionally, some down-regulated transportome genes were found to be closely linked to epithelial cell differentiation. Furthermore, the observed decrease in genes coding for calcium and chloride transport might be a mechanism for evasion of apoptosis. In conclusion, the current work provides a comprehensive overview of the altered transportome expression and its association with predicted PDAC malignancy with special focus on the epithelial compartment.

A systematic review of upper extremity casting for children and adults with central nervous system motor disorders

Objective: To summarize evidence on the use of upper extremity casting designed to achieve reductions in contracture, tone, pain, function, oedema or spasticity in the elbow, wrist or hand of adults and children with neurological conditions.

Data sources: A search was conducted of the Cochrane Database of Systematic Reviews; the electronic databases MEDLINE, EMBASE, CINAHL, PEDro, OT-Seeker; Google Scholar; reference lists of retrieved trial reports and review articles.

Review methods: Two independent reviewers determined whether retrieved study abstracts met inclusion criteria: human subjects; >50% of participants children or adults described as having brain injury, cerebral palsy or stroke. Methodological quality of randomized controlled trials was rated using the PEDro scale (1—10 highest).

Results: Thirty-one papers were retrieved and 23 studies appraised: three were randomized controlled trials and four were systematic reviews. Over three-quarters of the studies, excluding systematic reviews, were lower level evidence (n = 4 level V; n = 4 level IV; n = 1 level III). Methodological quality of randomized controlled trials was high (PEDro 8, 8 and 9) and there were modest positive short-term outcomes for two trials, although they did not include no-stretch comparison conditions. Safety issues typically included pain or skin breakdown; two adverse events were not cast related.

Conclusion: While theoretical rationales suggest upper limb casting should be effective there is insufficient high-quality evidence regarding impact or long-term effects to either support or abandon this practice. High variability in casting protocols indicates little consistency or consensus in practice. As maximum or low-load stretch are rationales for cast application, the absence of no-stretch conditions in existing trials is a major weakness in current evidence.

Electronic structure of antibiotic erythromycin

The electronic structure of erythromycin A (ERYMA) molecule has been studied by UV photoelectron spectroscopy and assigned (in the low ionization energy region only) by empirical arguments. The two orbitals with highest energy (lowest ionization energy) are localized on the nitrogen of the desosamine sugar functional group and on the ester group of macrolide (lactone) ring. We discuss how these orbital energies can help to rationalize the known mode of binding of ERYMA to their biological receptors.

The study of the electronic structure of some N-heterocyclic carbenes (NHCs) by variable energy photoelectron spectroscopy

UV and X-ray photoelectron spectra of three N-heterocyclic carbenes under synchrotron radiation reveal details of their electronic structure and are used as a benchmark to test computational methods for treating core ionizations in systems with unusual electronic structures.

The Gibbs free energy of formation of halogenated benzenes, benzoates and phenols and their potential role as electron acceptors in anaerobic environments

The sequence of redox reactions in the natural environment generally follows the electron affinity of the electron acceptors present and can be rationalized by the redox potentials of the appropriate half-reactions. Answering the question how halogenated aromatics fit into this sequence requires information on their Gibbs free energy of formation values. In 1992 Gibbs free energy data for various classes of halogenated aromatic compounds were systematically explored for the first time based on Benson’s group contribution method. Since then more accurate quantum chemical calculation methods have become available. Here we use these methods to estimate enthalpy and Gibbs free energy of formation values of all chlorinated and brominated phenols. These data and similar state-of-the-art datasets for halogenated benzenes and benzoates were then used to calculate two-electron redox potentials of halogenated aromatics for standard conditions and for pH 7. The results underline the need to take speciation into consideration when evaluating redox potentials at pH 7 and highlight the fact that halogenated aromatics are excellent electron acceptors in aqueous environments.

ANO1 (TMEM16A) in pancreatic ductal adenocarcinoma (PDAC)

Pancreatic ductal adenocarcinoma (PDAC) has one of the worst survival rates of all cancers. ANO1 (TMEM16A) is a recently identified Ca²⁺-activated Cl⁻ channel (CaCC) that is upregulated in several tumors. Although ANO1 was subject to extensive studies in the recent years, its pathophysiological function has only been poorly understood. The aim of the present study is to establish the significance of ANO1 in PDAC behavior and demarcate its roles in PDAC from those of the volume-regulated anion channel (VRAC). We performed qPCR and Western blot measurements on different PDAC cell lines (Panc-1, Mia PaCa 2, Capan-1, AsPC-1, BxPC-3) and compared the results to those obtained in a human pancreatic ductal epithelium (HPDE) cell line. All cancer cell lines showed an upregulation of ANO1 on mRNA and protein levels. Whole-cell patch-clamp recordings identified large Ca²⁺ and voltage-dependent Cl⁻ currents in PDAC cells. Using siRNA knockdown of ANO1 and three ANO1 inhibitors (T16A_inh-A01, CaCC_inh-A01, and NS3728), we found that ANO1 is the main constituent of CaCC current in PDAC cells. We further characterized these three inhibitors and found that they had unspecific effects on the free intracellular calcium concentration. Functional studies on PDAC behavior showed that surprisingly inhibition of ANO1 did not influence cellular proliferation. On the other hand, we found ANO1 channel to be pivotal in PDAC cell migration as assessed in wound healing experiments.

Photoelectron Spectroscopy of Heterocycles. Phenyloxiranes

The Hel photoelectron spectra of 2-phenyloxirane, 2,2-diphenyloxirane, trans-2.3-diphenyloxirane, 2,2,3-triphenyloxirane, and 2,2,3,3-tetraphenyloxirane are reported. Comparison with the spectra of ethylene oxide (oxirane), benzene, and the following phenylethenes-styrene (1). I,1-diphenylethene (2), cis-stilbene (3), trans-stilbene (4), triphenylethene (5), and tetraphenylethene (6) - allowed to assign the lower ionization energies of the phenyloxiranes. Splitting of the lowest energy benzene π-orbitals is qualitatively the same in both classes of compounds. Because of the perpendicular orientation of the oxygen lone-pair in comparison to the π-electrons of the ethylene double bond this splitting is considerably smaller in phenyloxiranes.

Photoelectron Spectroscopy of Heterocycles 1-(Diazinyl)-2-(Pyridyl)-ethenes (Triazastilbenes)

The photoelectron (PE) spectra of 1-(4-pyrimidyl)-2-(3-pyridyl)-ethene 1, 1-(2-pyrimidyl)-2- (3-pyridyl)-ethene 2, 1-(4-pyridazinyl)-2-(3-pyridyl)-ethene 3, 1-(3-pyridazinyl)-2-(3-pyridyl)- ethene 4 and 1-(2-pyrazinyl)-2-(3-pyridyl)-ethene 5 all in their trans conformations have been recorded using Hel radiation. Comparisons with the PE spectra of styrylpyridines, dipyridylethenes and diazabenzenes allowed the assignment of all ionization energies, Ei, corresponding to π- and nitrogen lone pair ionizations in the region of Ei < 12 eV. The variations in PE spectra of five isomeric triazastilbenes studied are due to different nitrogen atom positions in the diazinyl ring.

Das Photoelektronenspektrum von Pyridin-N-Oxid anhand von Hel/Hell- Intensitäten [1] / Assignment of the Pyridine-N-oxide Photoelectron Spectrum on the Basis of Hel/Hell Intensities [1]

Comparison of Hel and Hell photoelectron (PE) spectra of pyridine-N-oxide enables the completion of the assignment of its electronic structure

Photoelectron Spectroscopy of Heterocycles. Polypyridines

The photoelectron (PE) spectra of 2,2′-bipyridine 1, 2,2′:6′,2″-terpyridine 2, and 2,2′,2″,2‴-tetrapyridine 3 have been measured using He I radiation. For 1-3 standard SCF LCAO MO calculations wer also performed. Comparison of PE spectra and these calculations allowed the assignment of π-ionizations and indirectly also the nitrogen lone pair ionizations in 1-3. Factors influencing the conformations of 1-3 in the gas phase are also mentioned.

Notiz: Quantification of Symmetry

A new mathematical criterion is suggested for symmetry ranking, i.e. determination of an “absolute symmetry scale” for discrete, finite groups. The criterion is based on both, the periods (orders) of each group element and the order of the group itself. This is different from the current criteria which consider only the orders of the groups themselves. The symmetry ranking, based on the new criterion, is applied to the symmetry point groups.

Role of vesicular nucleotide transporter VNUT (SLC17A9) in release of ATP from AR42J cells and mouse pancreatic acinar cells

ATP is released from cells in response to various stimuli. Our previous studies on pancreas indicated that pancreatic acini could be major stores of secreted ATP. In the present study, our aim was to establish the role of the vesicular nucleotide transporter (VNUT), SLC17A9, in storage and release of ATP. Freshly prepared acini from mice and AR42J rat acinar cells were used in this study. We illustrate that in AR42J cells, quinacrine (an ATP store marker) and Bodipy ATP (a fluorescent ATP analog) co-localized with VNUT-mCherry to vesicles/granules. Furthermore, in acini and AR42J cells, a marker of the zymogen granule membranes, Rab3D, and VNUT co-localized. Dexamethasone treatment of AR42J cells promoted formation of acinar structures, paralleled by increased amylase and VNUT expression, and increased ATP release in response to cholinergic stimulation. Mechanical stimulus (pressure) and cell swelling also induced ATP release, but this was not influenced by dexamethasone, most likely indicating different non-zymogen-related release mechanism. In conclusion, we propose that VNUT-dependent ATP release pathway is associated with agonist-induced secretion process and downstream purinergic signalling in pancreatic ducts.

Characterisation of the electronic structure of some stable nitroxyl radicals using variable energy photoelectron spectroscopy

Core and valence ionizations of three stable nitroxyl radicals studied using synchrotron radiation reveal strong intramolecular interactions in amide derivatives.