Interplay between microdynamics and macrorheology in vesicle suspensions

The microscopic dynamics of objects suspended in a fluid determines the macroscopic rheology of a suspension. For example, as shown by Danker and Misbah [Phys. Rev. Lett. {\bf 98}, 088104 (2007)], the viscosity of a dilute suspension of fluid-filled vesicles is a non-monotonic function of the viscosity contrast (the ratio between the viscosities of the internal encapsulated and the external suspending fluids) and exhibits a minimum at the critical point of the tank-treading-to-tumbling transition. By performing numerical simulations, we recover this effect and demonstrate that it persists for a wide range of vesicle parameters such as the concentration, membrane deformability, or swelling degree. We also explain why other numerical and experimental studies lead to contradicting results. Furthermore, our simulations show that this effect even persists in non-dilute and confined suspensions, but that it becomes less pronounced at higher concentrations and for more swollen vesicles. For dense suspensions and for spherical (circular in 2D) vesicles, the intrinsic viscosity tends to depend weakly on the viscosity contrast.Comment: 9 pages, 9 figures, to appear in Soft Matter (2014

The structural and diagenetic evolution of injected sandstones: examples from the Kimmeridgian of NE Scotland

Abstract: Injected sandstones occurring in the Kimmeridgian of NE Scotland along the bounding Great Glen and Helmsdale faults formed when basinal fluids moved upward along the fault zones, fluidizing Oxfordian sands encountered at shallow depth and injecting them into overlying Kimmeridgian strata. The orientation of dykes, in addition to coeval faults and fractures, was controlled by a stress state related to dextral strike-slip along the bounding fault zones. Diagenetic studies of cements allow the reconstruction of the fluid flow history. The origin of deformation bands in sandstone dykes and sills was related to the contraction of the host-rocks against dyke and sill walls following the initial stage of fluidized flow, and these deformation bands are the earliest diagenetic imprint. Early non-ferroan calcite precipitated in injection structures at temperatures between 70 and 100 8C, indicating that it precipitated from relatively hot basinal fluids that drove injection. Coeval calcite-filled fractures show similar temperatures, suggesting that relatively hot fluids were responsible for calcite precipitation in any permeable pathway created by dextral simple shear along the faults. During progressive burial, percolating sea water was responsible for completely cementing the still relatively porous injected sandstones with a second generation of ferroan calcite, which contains fluid inclusions with homogenization temperatures below 50 8C. During this phase, depositional host sandstones were also cemented

Nuclear receptors in vascular biology

Nuclear receptors sense a wide range of steroids and hormones (estrogens, progesterone, androgens, glucocorticoid, and mineralocorticoid), vitamins (A and D), lipid metabolites, carbohydrates, and xenobiotics. In response to these diverse but critically important mediators, nuclear receptors regulate the homeostatic control of lipids, carbohydrate, cholesterol, and xenobiotic drug metabolism, inflammation, cell differentiation and development, including vascular development. The nuclear receptor family is one of the most important groups of signaling molecules in the body and as such represent some of the most important established and emerging clinical and therapeutic targets. This review will highlight some of the recent trends in nuclear receptor biology related to vascular biology

Long term geological record of a global deep subsurface microbial habitat in sand injection complexes

Peer reviewedPublisher PD

Perivascular Fat and the Microcirculation: Relevance to Insulin Resistance, Diabetes, and Cardiovascular Disease

Type 2 diabetes and its major risk factor, obesity, are a growing burden for public health. The mechanisms that connect obesity and its related disorders, such as insulin resistance, type 2 diabetes, and hypertension, are still undefined. Microvascular dysfunction may be a pathophysiologic link between insulin resistance and hypertension in obesity. Many studies have shown that adipose tissue-derived substances (adipokines) interact with (micro)vascular function and influence insulin sensitivity. In the past, research focused on adipokines from perivascular adipose tissue (PVAT). In this review, we focus on the interactions between adipokines, predominantly from PVAT, and microvascular function in relation to the development of insulin resistance, diabetes, and cardiovascular disease

Therapeutic Surgical Management of Palpable Melanoma Groin Metastases: Superficial or Combined Superficial and Deep Groin Lymph Node Dissection

Item does not contain fulltextBACKGROUND: Management of patients with clinically detectable lymph node metastasis to the groin is by ilioinguinal or combined superficial and deep groin dissection (CGD) according to most literature, but in practice superficial groin dissection (SGD) only is still performed in some centers. The aim of this study is to evaluate the experience in CGD versus SGD patients in our center. METHODS: Between 1991 and 2009, 121 therapeutic CGD and 48 SGD were performed in 169 melanoma patients with palpable groin metastases at our institute. Median follow-up was 20 and, for survivors, 45 months. RESULTS: In this heterogeneous group of patients, overall (OS) and disease-free survival, local control rates, and morbidity rates were not significantly different between CGD and SGD patients. However, CGD patients had a trend towards more chronic lymphedema. Superficial lymph node ratio, the number of positive superficial lymph nodes, and the presence of deep nodes were prognostic factors for survival. CGD patients with involved deep lymph nodes (24.8%) had estimated 5-year OS of 12% compared with 40% with no involved deep lymph nodes (p = 0.001). Preoperative computed tomography (CT) scan had high negative predictive value of 91% for detection of pelvic nodal involvement. CONCLUSIONS: This study demonstrated that survival and local control do not differ for patients with palpable groin metastases treated by CGD or SGD. Patients without pathological iliac nodes on CT might safely undergo SGD, while CGD might be reserved for patients with multiple positive nodes on SGD and/or positive deep nodes on CT scan

Polycomb recruitment attenuates retinoic acid-induced transcription of the bivalent NR2F1 gene

Polycomb proteins play key roles in mediating epigenetic modifications that occur during cell differentiation. The Polycomb repressive complex 2 (PRC2) mediates the tri-methylation of histone H3 lysine 27 (H3K27me3). In this study, we identify a distinguishing feature of two classes of PRC2 target genes, represented by the Nr2F1 (Coup-TF1) and the Hoxa5 gene, respectively. Both genes are transcriptionally activated by all-trans retinoic acid (RA) and display increased levels of the permissive H3K9/K14ac and tri-methylated histone H3 lysine 4 epigenetic marks in response to RA. However, while in response to RA the PRC2 and H3K27me3 marks are greatly decreased at the Hoxa5 promoter, these marks are initially increased at the Nr2F1 promoter. Functional depletion of the essential PRC2 protein Suz12 by short hairpin RNA (shRNA) technology enhanced the RA-associated transcription of Nr2F1, Nr2F2, Meis1, Sox9 and BMP2, but had no effect on the Hoxa5, Hoxa1, Cyp26a1, Cyp26b1 and RARβ2 transcript levels in wild-type embryonic stem cells. We propose that PRC2 recruitment attenuates the RA-associated transcriptional activation of a subset of genes. Such a mechanism would permit the fine-tuning of transcriptional networks during differentiation

Essential Role of Chromatin Remodeling Protein Bptf in Early Mouse Embryos and Embryonic Stem Cells

We have characterized the biological functions of the chromatin remodeling protein Bptf (Bromodomain PHD-finger Transcription Factor), the largest subunit of NURF (Nucleosome Remodeling Factor) in a mammal. Bptf mutants manifest growth defects at the post-implantation stage and are reabsorbed by E8.5. Histological analyses of lineage markers show that Bptf−/− embryos implant but fail to establish a functional distal visceral endoderm. Microarray analysis at early stages of differentiation has identified Bptf-dependent gene targets including homeobox transcriptions factors and genes essential for the development of ectoderm, mesoderm, and both definitive and visceral endoderm. Differentiation of Bptf−/− embryonic stem cell lines into embryoid bodies revealed its requirement for development of mesoderm, endoderm, and ectoderm tissue lineages, and uncovered many genes whose activation or repression are Bptf-dependent. We also provide functional and physical links between the Bptf-containing NURF complex and the Smad transcription factors. These results suggest that Bptf may co-regulate some gene targets of this pathway, which is essential for establishment of the visceral endoderm. We conclude that Bptf likely regulates genes and signaling pathways essential for the development of key tissues of the early mouse embryo

A before-after implementation trial of smoking cessation guidelines in hospitalized veterans

Abstract Background Although most hospitalized smokers receive some form of cessation counseling during hospitalization, few receive outpatient cessation counseling and/or pharmacotherapy following discharge, which are key factors associated with long-term cessation. US Department of Veterans Affairs (VA) hospitals are challenged to find resources to implement and maintain the kind of high intensity cessation programs that have been shown to be effective in research studies. Few studies have applied the Chronic Care Model (CCM) to improve inpatient smoking cessation. Specific objectives The primary objective of this protocol is to determine the effect of a nurse-initiated intervention, which couples low-intensity inpatient counseling with sustained proactive telephone counseling, on smoking abstinence in hospitalized patients. Key secondary aims are to determine the impact of the intervention on staff nurses' attitudes toward providing smoking cessation counseling; to identify barriers and facilitators to implementation of smoking cessation guidelines in VA hospitals; and to determine the short-term cost-effectiveness of implementing the intervention. Design Pre-post study design in four VA hospitals Participants Hospitalized patients, aged 18 or older, who smoke at least one cigarette per day. Intervention The intervention will include: nurse training in delivery of bedside cessation counseling, electronic medical record tools (to streamline nursing assessment and documentation, to facilitate prescription of pharmacotherapy), computerized referral of motivated inpatients for proactive telephone counseling, and use of internal nursing facilitators to provide coaching to staff nurses practicing in non-critical care inpatient units. Outcomes The primary endpoint is seven-day point prevalence abstinence at six months following hospital admission and prolonged abstinence after a one-month grace period. To compare abstinence rates during the intervention and baseline periods, we will use random effects logistic regression models, which take the clustered nature of the data within nurses and hospitals into account. We will assess attitudes of staff nurses toward cessation counseling by questionnaire and will identify barriers and facilitators to implementation by using clinician focus groups. To determine the short-term incremental cost per quitter from the perspective of the VA health care system, we will calculate cessation-related costs incurred during the initial hospitalization and six-month follow-up period. Trial number NCT00816036http://deepblue.lib.umich.edu/bitstream/2027.42/112349/1/13012_2009_Article_190.pd