Seepage forces, important factors in the formation of horizontal hydraulic fractures and bedding-parallel fibrous veins ('beef' and 'cone-in-cone')

International audienceBedding-parallel fibrous veins ('beef' and 'cone-in-cone') are common to a number of sedimentary basins, especially those containing black shale. The type locality is SW England. The commonest mineral in the fibres is calcite. The fibres indicate vertical opening, against the force of gravity. In the past, this has been attributed to fluid overpressure. However, a simple analysis, based on Von Terzaghi's concepts, leads to the conclusion that, for the fractures to be horizontal, either the rock must be anisotropic, or it must be subject to horizontal compression. By means of a more complete analysis, supported by physical models, we show that horizontal fractures are to be expected, even if the rock is isotropic and there are no tectonic stresses. Upward fluid flow, in response to an overpressure gradient, imparts seepage forces to all elements of the solid framework. The seepage forces counteract the weight of the rock, and even surpass it, generating a tensile effective stress. The process may lead, either to tensile hydraulic fracturing, or to dilatant shear failure. We suggest that these two failure modes, and the availability of suitable solutes, explain the frequent occurrence of 'beef' and 'cone-in-cone' respectively

Metformin Attenuates Palmitate-Induced Endoplasmic Reticulum Stress, Serine Phosphorylation of IRS-1 and Apoptosis in Rat Insulinoma Cells

Lipotoxicity refers to cellular dysfunctions caused by elevated free fatty acid levels playing a central role in the development and progression of obesity related diseases. Saturated fatty acids cause insulin resistance and reduce insulin production in the pancreatic islets, thereby generating a vicious cycle, which potentially culminates in type 2 diabetes. The underlying endoplasmic reticulum (ER) stress response can lead to even β-cell death (lipoapoptosis). Since improvement of β-cell viability is a promising anti-diabetic strategy, the protective effect of metformin, a known insulin sensitizer was studied in rat insulinoma cells. Assessment of palmitate-induced lipoapoptosis by fluorescent microscopy and by detection of caspase-3 showed a significant decrease in metformin treated cells. Attenuation of β-cell lipotoxicity was also revealed by lower induction/activation of various ER stress markers, e.g. phosphorylation of eukaryotic initiation factor 2α (eIF2α), c-Jun N-terminal kinase (JNK), insulin receptor substrate-1 (IRS-1) and induction of CCAAT/enhancer binding protein homologous protein (CHOP). Our results indicate that the β-cell protective activity of metformin in lipotoxicity can be at least partly attributed to suppression of ER stress

Assessing the level of healthcare information technology adoption in the United States: a snapshot

BACKGROUND: Comprehensive knowledge about the level of healthcare information technology (HIT) adoption in the United States remains limited. We therefore performed a baseline assessment to address this knowledge gap. METHODS: We segmented HIT into eight major stakeholder groups and identified major functionalities that should ideally exist for each, focusing on applications most likely to improve patient safety, quality of care and organizational efficiency. We then conducted a multi-site qualitative study in Boston and Denver by interviewing key informants from each stakeholder group. Interview transcripts were analyzed to assess the level of adoption and to document the major barriers to further adoption. Findings for Boston and Denver were then presented to an expert panel, which was then asked to estimate the national level of adoption using the modified Delphi approach. We measured adoption level in Boston and Denver was graded on Rogers' technology adoption curve by co-investigators. National estimates from our expert panel were expressed as percentages. RESULTS: Adoption of functionalities with financial benefits far exceeds adoption of those with safety and quality benefits. Despite growing interest to adopt HIT to improve safety and quality, adoption remains limited, especially in the area of ambulatory electronic health records and physician-patient communication. Organizations, particularly physicians' practices, face enormous financial challenges in adopting HIT, and concerns remain about its impact on productivity. CONCLUSION: Adoption of HIT is limited and will likely remain slow unless significant financial resources are made available. Policy changes, such as financial incentivesto clinicians to use HIT or pay-for-performance reimbursement, may help health care providers defray upfront investment costs and initial productivity loss

The N-Terminal Domain of ERK1 Accounts for the Functional Differences with ERK2

The Extracellular Regulated Kinase 1 and 2 transduce a variety of extracellular stimuli regulating processes as diverse as proliferation, differentiation and synaptic plasticity. Once activated in the cytoplasm, ERK1 and ERK2 translocate into the nucleus and interact with nuclear substrates to induce specific programs of gene expression. ERK1/2 share 85% of aminoacid identity and all known functional domains and thence they have been considered functionally equivalent until recent studies found that the ablation of either ERK1 or ERK2 causes dramatically different phenotypes. To search a molecular justification of this dichotomy we investigated whether the different functions of ERK1 and 2 might depend on the properties of their cytoplasmic-nuclear trafficking. Since in the nucleus ERK1/2 is predominantly inactivated, the maintenance of a constant level of nuclear activity requires continuous shuttling of activated protein from the cytoplasm. For this reason, different nuclear-cytoplasmic trafficking of ERK1 and 2 would cause a differential signalling capability. We have characterised the trafficking of fluorescently tagged ERK1 and ERK2 by means of time-lapse imaging in living cells. Surprisingly, we found that ERK1 shuttles between the nucleus and cytoplasm at a much slower rate than ERK2. This difference is caused by a domain of ERK1 located at its N-terminus since the progressive deletion of these residues converted the shuttling features of ERK1 into those of ERK2. Conversely, the fusion of this ERK1 sequence at the N-terminus of ERK2 slowed down its shuttling to a similar value found for ERK1. Finally, computational, biochemical and cellular studies indicated that the reduced nuclear shuttling of ERK1 causes a strong reduction of its nuclear phosphorylation compared to ERK2, leading to a reduced capability of ERK1 to carry proliferative signals to the nucleus. This mechanism significantly contributes to the differential ability of ERK1 and 2 to generate an overall signalling output

Stimulation of osteogenic differentiation in human osteoprogenitor cells by pulsed electromagnetic fields: an in vitro study

Background: Although pulsed electromagnetic field (PEMF) stimulation may be clinically beneficial during fracture healing and for a wide range of bone disorders, there is still debate on its working mechanism. Mesenchymal stem cells are likely mediators facilitating the observed clinical effects of PEMF. Here, we performed in vitro experiments to investigate the effect of PEMF stimulation on human bone marrow-derived stromal cell (BMSC) metabolism and, specifically, whether PEMF can stimulate their osteogenic differentiation. Methods: BMSCs derived from four different donors were cultured in osteogenic medium, with the PEMF treated group being continuously exposed to a 15 Hz, 1 Gauss EM field, consisting of 5-millisecond bursts with 5-microsecond pulses. On culture day 1, 5, 9, and 14, cells were collected for biochemical analysis (DNA amount, alkaline phosphatase activity, calcium deposition), expression of various osteoblast-relevant genes and activation of extracellular signal-regulated kinase (ERK) signaling. Differences between treated and control groups were analyzed using the Wilcoxon signed rank test, and considered significant when p < 0.05. Results: Biochemical analysis revealed significant, differentiation stage-dependent, PEMF-induced differences: PEMF increased mineralization at day 9 and 14, without altering alkaline phosphatase activity. Cell proliferation, as measured by DNA amounts, was not affected by PEMF until day 14. Here, DNA content stagnated in PEMF treated group, resulting in less DNA compared to control. Quantitative RT-PCR revealed that during early culture, up to day 9, PEMF treatment increased mRNA levels of bone morphogenetic protein 2, transforming growth factor-beta 1, osteoprotegerin, matrix metalloproteinase-1 and-3, osteocalcin, and bone sialoprotein. In contrast, receptor activator of NF-B ligand expression was primarily stimulated on day 14. ERK1/2 phosphorylation was not affected by PEMF stimulation. Conclusions: PEMF exposure of differentiating human BMSCs enhanced mineralization and seemed to induce differentiation at the expense of proliferation. The osteogenic stimulus of PEMF was confirmed by the up-regulation of several osteogenic marker genes in the PEMF treated group, which preceded the deposition of mineral itself. These findings indicate that PEMF can directly stimulate osteoprogenitor cells towards osteogenic differentiation. This supports the theory that PEMF treatment may recruit these cells to facilitate an osteogenic response in vivo. © 2010 Jansen et al; licensee BioMed Central Ltd

Variants in the <em>DDX6-CXCR5</em> autoimmune disease risk locus influence the regulatory network in immune cells and salivary gland

\ua9 2025 The Author(s). Objectives: Sj\uf6gren\u27s disease (SjD) and systemic lupus erythematosus (SLE) share genetic risk at the DDX6-CXCR5 locus (11q23.3). Identifying and functionally characterising shared SNPs spanning this locus can provide new insights into common genetic mechanisms of autoimmunity. Methods: Transdisease meta-analyses, fine-mapping, and bioinformatic analyses prioritised shared likely functional single nucleotide polymorphisms (SNPs) for allele-specific and cell type–specific functional interrogation using electromobility shift, luciferase reporter, and quantitative chromatin conformation capture assays and clustered regularly interspaced short palindromic repeat (CRISPR) gene regulation. Results: Five shared SNPs were identified as likely functional in primary human immune cells, salivary gland and kidney tissues: rs57494551, rs4936443, rs4938572, rs7117261, and rs4938573. All 5 SNPs exhibited cell type-specific and allele-specific effects on nuclear protein binding affinity and enhancer/promoter regulatory activity in immune, salivary gland epithelial, and kidney epithelial cell models. Mapping of chromatin–chromatin interactions revealed a chromatin regulatory network that expanded beyond DDX6 and CXCR5 to include PHLDB1, lnc-PHLDB1-1, BCL9L, TRAPPC4, among others. Coalescence of functional assays and multiomic data analyses indicated that these SNPs likely modulate the activity of 3 regulatory regions: intronic rs57494551 regulatory region, intergenic SNP haplotype (rs4938572, rs4936443, and rs7117261) regulatory region, and rs4938573 regulatory region upstream of the CXCR5 promoter. Conclusions: Shared genetic susceptibly at the DDX6-CXCR5 locus in SjD and SLE likely alters common mechanisms of autoimmunity, including interferon signalling (DDX6), autophagy (TRAPPC4), and lymphocytic infiltration of disease-target tissues (CXCR5). Further, using multiomic data from patients with SjD, combined with bioinformatic and in vitro functional studies, can provide mechanistic insights into how genetic risk influences the biological pathways that drive complex autoimmunity

Negative feedback regulation of the ERK1/2 MAPK pathway

The extracellular signal-regulated kinase 1/2 (ERK1/2) mitogen-activated protein kinase (MAPK) signalling pathway regulates many cellular functions, including proliferation, differentiation, and transformation. To reliably convert external stimuli into specific cellular responses and to adapt to environmental circumstances, the pathway must be integrated into the overall signalling activity of the cell. Multiple mechanisms have evolved to perform this role. In this review, we will focus on negative feedback mechanisms and examine how they shape ERK1/2 MAPK signalling. We will first discuss the extensive number of negative feedback loops targeting the different components of the ERK1/2 MAPK cascade, specifically the direct posttranslational modification of pathway components by downstream protein kinases and the induction of de novo gene synthesis of specific pathway inhibitors. We will then evaluate how negative feedback modulates the spatiotemporal signalling dynamics of the ERK1/2 pathway regarding signalling amplitude and duration as well as subcellular localisation. Aberrant ERK1/2 activation results in deregulated proliferation and malignant transformation in model systems and is commonly observed in human tumours. Inhibition of the ERK1/2 pathway thus represents an attractive target for the treatment of malignant tumours with increased ERK1/2 activity. We will, therefore, discuss the effect of ERK1/2 MAPK feedback regulation on cancer treatment and how it contributes to reduced clinical efficacy of therapeutic agents and the development of drug resistance