Satellite-cell pool size does matter: Defining the myogenic potency of aging skeletal muscle

AbstractThe deteriorating in vivo environment is thought to play a major role in reduced stem cell function with age. The capacity of stem cells to support tissue maintenance depends not only on their response to cues from the surrounding niche, but also on their abundance. Here, we investigate satellite cell (myogenic stem cell) pool size and its potential to participate in muscle maintenance through old age. The numbers and performance of mouse satellite cells have been analyzed using molecular markers that exclusively characterize quiescent satellite cells and their progeny as they transit through proliferation, differentiation and generation of reserve cells. The study establishes that abundance of resident satellite cells declines with age in myofibers from both fast- and slow-twitch muscles. Nevertheless, the inherent myogenic potential of satellite cells does not diminish with age. Furthermore, the aging satellite cell niche retains the capacity to support effective myogenesis upon enrichment of the mitogenic milieu with FGF. Altogether, satellite cell abundance, but not myogenic potential, deteriorates with age. This study suggests that the population of satellite cells that participate in myofiber maintenance during routine muscle utilization is not fully replenished throughout life

A critical appreciation of intangible resources in PharmaNutrition

Background: Organizations in knowledge-intensive industries such as the field of PharmaNutrition benefit from a critical consideration of intangible resources for innovation performance and competitive advantage. Effective management of these resources, however, is complicated due to difficulties in their identification, appropriation, application, and evaluation. As a consequence, knowledge-intensive organizations are at risk of suboptimal exploitation of their most important value drivers. Methods: The literature on organizational intangible resources was reviewed as part of an ongoing investigation into effective management of intangible resources in the PharmaNutrition-specific context. Results: Although high-level dimensions of intangible resources are recognized across industries, the identity and relevance of various lower-level components are heterogenous and dependent on organization's unique situational attributes. Despite the existence of historical, industry-sourced tick-the-box lists presented here, an analysis of industry-specific characteristics of intangible resources and mechanisms to appropriate their value is warranted to enable practitioners to innovate effectively and efficiently. Conclusions: This editorial aims to put the topics of intangible resources and their appropriability on the agenda, and invites scholars and practitioners to contribute to the advancement of our understanding regarding these topics through an online survey

The Infrared Luminosity Function of Galaxies in the Coma Cluster

An infrared survey of the central 650 arcmin$^2$ of the Coma cluster is used to determine the $H$ band luminosity function for the cluster. Redshifts are available for all galaxies in the survey with $H < 14.5$, and for this sample we obtain a good fit to a Schechter function with $H^*=11.13$ and $\alpha=-0.78$. These luminosity function parameters are similar to those measured for field galaxies in the infrared, which is surprising considering the very different environmental densities and, presumably, merger histories for field galaxies. For fainter galaxies, we use two independent techniques to correct for field galaxy contamination in the cluster population: the $B-R$ color-magnitude relation and an estimate for the level of background and foreground contamination from the literature. Using either method we find a steep upturn for galaxies with $14 < H < 16$, with slope $\alpha \simeq 1.7$.Comment: 15 pages, 2 figures Accepted by ApJ Letter

Understanding the generation of methanol synthesis and water gas shift activity over copper-based catalysts – A spatially resolved experimental kinetic study using steady and non-steady state operation under CO/CO₂/H₂ feeds

AbstractUnderstanding the mechanism and generation of activity for methanol synthesis and the water gas shift reactions over copper-based catalysts remains a significant area of study in heterogeneous catalysis. In this work, steady and non-steady state experimental and kinetic modelling methods are presented to demonstrate changes in functionality of a Cu/ZnO/Al2O3 catalyst based on gas composition.Steady-state testing of a Cu/ZnO/Al2O3 catalyst, using experimental spatial discretisation approaches with fixed-bed, integral-operation micro reactors, has generated performance data over a range of PCO/PCO2 ratios (1–10). The data showed a mixture of observations where forward or reverse water gas shift was kinetically favourable, and also where the reaction was significantly limited by thermodynamic equilibrium. A steady state Langmuir–Hinshelwood model based on micro kinetics was most appropriate which includes kinetic descriptions of both directions of the water gas shift reaction. Using this method, the entire dataset could be predicted and an internal consistency within the kinetic model of the key adsorption constants was demonstrated.Non-steady state, ‘reactor start-up’, testing of a Cu/ZnO/Al2O3 catalyst marked a novel approach to further understanding the functionality of the catalyst. Initial changes in surface carbon and oxygen populations were quantified and linked to subsequent dynamic changes in methanol synthesis and water gas shift activity. Cu/ZnO and Cu/Al2O3 formulations were also evaluated and tested using kinetic models, permitting a structural and compositional comparison with Cu/ZnO/Al2O3

Optical mammography combined with fluorescence imaging: lesion detection using scatterplots

Using scatterplots of 2 or 3 parameters, diffuse optical tomography and fluorescence imaging are combined to improve detectability of breast lesions. Small or low contrast phantom-lesions that were missed in the optical and fluorescence images were detected in the scatterplots. In patient measurements, all tumors were visible and easily differentiated from artifacts and areolas in the scatterplots. The different rate of intake and wash out of the fluorescent contrast agent in the healthy versus malignant tissues was also observed in the scatterplot: this information can be used to discriminate malignant lesion from normal structures

Preoperative and Early Postoperative Quality of Life Predict Survival in Potentially Curable Patients with Esophageal Cancer

Background: In patients with esophageal cancer, evidence for prognostic significance of preoperative quality of life (QoL) is limited, while the prognostic significance of postoperative QoL has not been investigated at all. Aim: To determine whether preoperative and postoperative QoL measurements can predict survival independently from clinical and pathological factors, in patients with potentially curable esophageal adenocarcinoma. Methods: A randomized controlled trial was performed from 1994 to 2000 in two academic medical centres, comparing transthoracic and transhiatal esophagectomy. QoL questionnaires were sent before and 3 months after surgery (Medical Outcome Study Short Form-20 and Rotterdam Symptom Checklist). Uni- and multivariate Cox regression analyses were used to examine firstly the prognostic value of preoperative QoL and several clinical factors, and secondly of postoperative QoL, several clinical factors, and pathological staging. Results: Out of 220 randomized patients, 199 participated in the QoL-study. In the multivariate preoperative model physical symptom scale (p = 0.021), tumor length (p = 0.034), and endosonographic T-stage (p = 0.003) were predictive for overall survival. In the postoperative multivariate analysis, social functioning (p = 0.035), pain (p = 0.026), and activity level (p = 0.037) predicted survival, besides pathological T-stage (p < 0.001) and N-stage (p < 0.001). Conclusion: In the present paper the first large consecutive series of potentially curable esophageal cancer patients is presented in whom prospectively collected QoL data before and after potentially curative surgical resection were used to predict survival. Both preoperative (physical symptoms) and postoperative (social functioning, pain, and activity level) QoL subscales are independent predictors of survival in potentially curable patients with esophageal adenocarcinoma

Coherent Backscattering of light in a magnetic field

This paper describes how coherent backscattering is altered by an external magnetic field. In the theory presented, magneto-optical effects occur inside Mie scatterers embedded in a non-magnetic medium. Unlike previous theories based on point-like scatterers, the decrease of coherent backscattering is obtained in leading order of the magnetic field using rigorous Mie theory. This decrease is strongly enhanced in the proximity of resonances, which cause the path length of the wave inside a scatterer to be increased. Also presented is a novel analysis of the shape of the backscattering cone in a magnetic field.Comment: 27 pages, 5 figures, Revtex, to appear in Phys. Rev.