Shear stress induced stimulation of mammalian cell metabolism

A flow apparatus was developed for the study of the metabolic response of anchorage dependent cells to a wide range of steady and pulsatile shear stresses under well controlled conditions. Human umbilical vein endothelial cell monolayers were subjected to steady shear stresses of up to 24 dynes/sq cm, and the production of prostacyclin was determined. The onset of flow led to a burst in prostacyclin production which decayed to a long term steady state rate (SSR). The SSR of cells exposed to flow was greater than the basal release level, and increased linearly with increasing shear stress. It is demonstrated that shear stresses in certain ranges may not be detrimental to mammalian cell metabolism. In fact, throughout the range of shear stresses studied, metabolite production is maximized by maximizing shear stress

The radiation problem from a vertical short dipole antenna above flat and lossy ground. Novel formulation in the spectral domain with closed form analytical solution in the high frequency regime

In this paper we consider the problem of radiation from a vertical short Hertzian dipole above flat lossy ground, which represents the well known in the literature Sommerfeld radiation problem. The problem is formulated in a novel spectral domain approach, and by inverse three dimensional Fourier transformation the expressions for the received electric and magnetic field in the physical space are derived as one dimensional integrals over the radial component of wavevector, in cylindrical coordinates. Subsequent use of the Stationary Phase Method in the high frequency regime yields closed form analytical solutions for the received EM field vectors, which coincide with the corresponding reflected EM field originating from the image point. In this way, we conclude that the so called in the literature space wave, i.e. line of sight plus reflected EM field, represents the total solution of the Sommerfeld problem in the high frequency regime, in which case the surface wave can be ignored. Finally, numerical results in the high frequency regime are presented in this paper, in comparison with corresponding numerical results based on Norton solution of the problem, i.e. space and surface waves

Bonus-Malus Systems with Two Component Mixture Models Arising from Different Parametric Families

Two component mixture distributions defined so that the component distributions do not necessarily arise from the same parametric family are employed for the construction of Optimal Bonus-malus Systems (BMS) with frequency and severity components. The proposed modelling framework is used for the first time in actuarial literature research and includes an abundance of alternative model choices to be considered by insurance companies when deciding on their Bonus-Malus pricing strategies. Furthermore, we advance one step further by assuming that all the parameters and mixing probabilities of the two component mixture distributions are modelled in terms of covariates, extending our previous work in Tzougas, Vrontos and Frangos (2014). Applying Bayes theorem we derive optimal BMS either by updating the posterior probability of the policyholders' classes of risk or by updating the posterior mean and the posterior variance. The resulting tailor-made premiums are calculated via the expected value and variance principles and are compared to those based only on the a posteriori criteria. The use of the variance principle in a Bonus-Malus ratemaking scheme in a way that takes into consideration both the number and the costs of claims based on both the a priori and the a posterior classification criteria has not yet been proposed and can alter the resulting premiums significantly, providing the actuary with useful alternative tariff structures

Risk Classification for Claim Counts and Losses Using Regression Models for Location, Scale and Shape

This paper presents and compares different risk classi?cation models for the frequency and severity of claims employing regression models for location, scale and shape. The differences between these models are analyzed through the mean and the variance of the annual number of claims and the costs of claims of the insureds, who belong to different risk classes and interesting results about claiming behaviour are obtained. Furthermore, the resulting a priori premiums rates are calculated via the expected value and standard deviation principles with independence between the claim frequency and severity components assumed

Single particle tracking in systems showing anomalous diffusion: the role of weak ergodicity breaking

Anomalous diffusion has been widely observed by single particle tracking microscopy in complex systems such as biological cells. The resulting time series are usually evaluated in terms of time averages. Often anomalous diffusion is connected with non-ergodic behaviour. In such cases the time averages remain random variables and hence irreproducible. Here we present a detailed analysis of the time averaged mean squared displacement for systems governed by anomalous diffusion, considering both unconfined and restricted (corralled) motion. We discuss the behaviour of the time averaged mean squared displacement for two prominent stochastic processes, namely, continuous time random walks and fractional Brownian motion. We also study the distribution of the time averaged mean squared displacement around its ensemble mean, and show that this distribution preserves typical process characteristic even for short time series. Recently, velocity correlation functions were suggested to distinguish between these processes. We here present analytucal expressions for the velocity correlation functions. Knowledge of the results presented here are expected to be relevant for the correct interpretation of single particle trajectory data in complex systems.Comment: 15 pages, 15 figures; References adde

Implementation Science to Accelerate Clean Cooking for Public Health

Clean cooking has emerged as a major concern for global health and development because of the enormous burden of disease caused by traditional cookstoves and fires. The World Health Organization has developed new indoor air quality guidelines that few homes will be able to achieve without replacing traditional methods with modern clean cooking technologies, including fuels and stoves. However, decades of experience with improved stove programs indicate that the challenge of modernizing cooking in impoverished communities includes a complex, multi-sectoral set of problems that require implementation research. The National Institutes of Health, in partnership with several government agencies and the Global Alliance for Clean Cookstoves, has launched the Clean Cooking Implementation Science Network that aims to address this issue. In this article, our focus is on building a knowledge base to accelerate scale-up and sustained use of the cleanest technologies in low- and middle-income countries. Implementation science provides a variety of analytical and planning tools to enhance effectiveness of clinical and public health interventions. These tools are being integrated with a growing body of knowledge and new research projects to yield new methods, consensus tools, and an evidence base to accelerate improvements in health promised by the renewed agenda of clean cooking.Fil: Rosenthal, Joshua. National Institutes Of Health. Fogarty International Center; Estados UnidosFil: Balakrishnan, Kalpana. Sri Ramachandra University; IndiaFil: Bruce, Nigel. University of Liverpool; Reino UnidoFil: Chambers, David. National Institutes of Health. National Cancer Institute; Estados UnidosFil: Graham, Jay. The George Washington University; Estados UnidosFil: Jack, Darby. Columbia University; Estados UnidosFil: Kline, Lydia. National Institutes Of Health. Fogarty International Center; Estados UnidosFil: Masera, Omar Raul. Universidad Nacional Autónoma de México; MéxicoFil: Mehta, Sumi. Global Alliance for Clean Cookstoves; Estados UnidosFil: Mercado, Ilse Ruiz. Universidad Nacional Autónoma de México; MéxicoFil: Neta, Gila. National Institutes of Health. National Cancer Institute; Estados UnidosFil: Pattanayak, Subhrendu. University of Duke; Estados UnidosFil: Puzzolo, Elisa. Global LPG Partnership; Estados UnidosFil: Petach, Helen. U.S. Agency for International Development; Estados UnidosFil: Punturieri, Antonello. National Heart, Lung, and Blood Institute; Estados UnidosFil: Rubinstein, Adolfo Luis. Instituto de Efectividad Clínica y Sanitaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sage, Michael. Centers for Disease Control and Prevention; Estados UnidosFil: Sturke, Rachel. National Institutes Of Health. Fogarty International Center; Estados UnidosFil: Shankar, Anita. University Johns Hopkins; Estados UnidosFil: Sherr, Kenny. University of Washington; Estados UnidosFil: Smith, Kirk. University of California at Berkeley; Estados UnidosFil: Yadama, Gautam. Washington University in St. Louis; Estados Unido

Functional characteristics of calcitonin gene-related peptide receptors in human Ewing's sarcoma WE-68 cells

AbstractCalcitonin gene-related peptide (CGRP) receptor activity was studied in WE-68 human Ewing's sarcoma cells. 125I-human CGRP bound in a time-dependent, reversible and saturable manner. Scatchard plots were compatible with the presence of a homogenous population of CGRP receptors with high affinity (Kd = 15 pM, and Bmax = 1.9 fmolmg protein). The potency order of unlabeled peptides, in the presence of radioligand, was: human CGRP-II > human CGRP = chick CGRP > rat CGRP = rat [Tyro]CGRP > human [Tyro] CGRP > > salmon calcitonin (CT) > rat [Tyro]CGRP-(28-37). Each peptide except CT and [Tyio]CGRP-(28-37) stimulated cyclic AMP generation in a concentration-dependent manner, and the relative potencies paralleled their relative ability in inhibiting 125I-human CGRP binding. We conclude that WE-68 Ewing's sarcoma cells express genuine CGRP receptors which upon activation lead to stimulation of cyclic AMP formation.Calcitonin gene-related peptide; Calcitonin; cyclic AMP; (Human; Ewing's sarcoma cell

The allosteric inhibition of glycine transporter 2 by bioactive lipid analgesics is controlled by penetration into a deep lipid cavity.

The role of lipids in modulating membrane protein function is an emerging and rapidly growing area of research. The rational design of lipids that target membrane proteins for the treatment of pathological conditions is a novel extension in this field and provides a step forward in our understanding of membrane transporters. Bioactive lipids show considerable promise as analgesics for the treatment of chronic pain and bind to a high-affinity allosteric binding site on the human glycine transporter 2 (GlyT2 or SLC6A5). Here we use a combination of medicinal chemistry, electrophysiology, and computational modelling to develop a rational structure activity relationship for lipid inhibitors and demonstrate the key role of the lipid tail interactions for GlyT2 inhibition. Specifically, we examine how lipid inhibitor head group stereochemistry, tail length and double bond position promote enhanced inhibition. Overall, the L-stereoisomer is generally a better inhibitor than the D-stereoisomer, longer tail length correlates with greater potency, and the position of the double bond influences the activity of the inhibitor. We propose that the binding of the lipid inhibitor deep into the allosteric binding pocket is critical for inhibition. Furthermore, this provides insight into the mechanism of inhibition of GlyT2 and highlights how lipids can modulate the activity of membrane proteins by binding to cavities between helices. The principles identified in this work have broader implications for the development of a larger class of compounds that could target SLC6 transporters for disease treatment

The problematic use of Information and Communication Technologies (ICT) in adolescents by the cross sectional JOITIC study

Background: The emerging field of Information and Communications Technology (ICT) has brought about new interaction styles. Its excessive use may lead to addictive behaviours. The objective is to determine the prevalence of the problematic use of ICT such as Internet, mobile phones and video games, among adolescents enrolled in mandatory Secondary Education (ESO in Spanish) and to examine associated factors. Methods: Cross sectional, multi-centric descriptive study. Population: 5538 students enrolled in years one to four of ESO at 28 schools in the Vallès Occidental region (Barcelona, Spain). Data collection: self-administered socio-demographic and ICT access questionnaire, and validated questionnaires on experiences related to the use of the Internet, mobile phones and video games (CERI, CERM, CERV). Results: Questionnaires were collected from 5,538 adolescents between the ages of 12 and 20 (77.3 % of the total response), 48.6 % were females. Problematic use of the Internet was observed in 13.6 % of the surveyed individuals; problematic use of mobile phones in 2.4 % and problematic use in video games in 6.2 %. Problematic Internet use was associated with female students, tobacco consumption, a background of binge drinking, the use of cannabis or other drugs, poor academic performance, poor family relationships and an intensive use of the computer. Factors associated with the problematic use of mobile phones were the consumption of other drugs and an intensive use of these devices. Frequent problems with video game use have been associated with male students, the consumption of other drugs, poor academic performance, poor family relationships and an intensive use of these games. Conclusions: This study offers information on the prevalence of addictive behaviours of the Internet, mobile phones and video game use. The problematic use of these ICT devices has been related to the consumption of drugs, poor academic performance and poor family relationships. This intensive use may constitute a risk marker for ICT addictio