Very Low Tidal Volume Ventilation with Associated Hypercapnia - Effects on Lung Injury in a Model for Acute Respiratory Distress Syndrome

BACKGROUND: Ventilation using low tidal volumes with permission of hypercapnia is recommended to protect the lung in acute respiratory distress syndrome. However, the most lung protective tidal volume in association with hypercapnia is unknown. The aim of this study was to assess the effects of different tidal volumes with associated hypercapnia on lung injury and gas exchange in a model for acute respiratory distress syndrome. METHODOLOGY/PRINCIPAL FINDINGS: In this randomized controlled experiment sixty-four surfactant-depleted rabbits were exposed to 6 hours of mechanical ventilation with the following targets: Group 1: tidal volume = 8-10 ml/kg/PaCO(2) = 40 mm Hg; Group 2: tidal volume = 4-5 ml/kg/PaCO(2) = 80 mm Hg; Group 3: tidal volume = 3-4 ml/kg/PaCO(2) = 120 mm Hg; Group 4: tidal volume = 2-3 ml/kg/PaCO(2) = 160 mm Hg. Decreased wet-dry weight ratios of the lungs, lower histological lung injury scores and higher PaO(2) were found in all low tidal volume/hypercapnia groups (group 2, 3, 4) as compared to the group with conventional tidal volume/normocapnia (group 1). The reduction of the tidal volume below 4-5 ml/kg did not enhance lung protection. However, oxygenation and lung protection were maintained at extremely low tidal volumes in association with very severe hypercapnia and no adverse hemodynamic effects were observed with this strategy. CONCLUSION: Ventilation with low tidal volumes and associated hypercapnia was lung protective. A tidal volume below 4-5 ml/kg/PaCO(2) 80 mm Hg with concomitant more severe hypercapnic acidosis did not increase lung protection in this surfactant deficiency model. However, even at extremely low tidal volumes in association with severe hypercapnia lung protection and oxygenation were maintained

Predicting Landscape-Genetic Consequences of Habitat Loss, Fragmentation and Mobility for Multiple Species of Woodland Birds

Inference concerning the impact of habitat fragmentation on dispersal and gene flow is a key theme in landscape genetics. Recently, the ability of established approaches to identify reliably the differential effects of landscape structure (e.g. land-cover composition, remnant vegetation configuration and extent) on the mobility of organisms has been questioned. More explicit methods of predicting and testing for such effects must move beyond post hoc explanations for single landscapes and species. Here, we document a process for making a priori predictions, using existing spatial and ecological data and expert opinion, of the effects of landscape structure on genetic structure of multiple species across replicated landscape blocks. We compare the results of two common methods for estimating the influence of landscape structure on effective distance: least-cost path analysis and isolation-by-resistance. We present a series of alternative models of genetic connectivity in the study area, represented by different landscape resistance surfaces for calculating effective distance, and identify appropriate null models. The process is applied to ten species of sympatric woodland-dependant birds. For each species, we rank a priori the expectation of fit of genetic response to the models according to the expected response of birds to loss of structural connectivity and landscape-scale tree-cover. These rankings (our hypotheses) are presented for testing with empirical genetic data in a subsequent contribution. We propose that this replicated landscape, multi-species approach offers a robust method for identifying the likely effects of landscape fragmentation on dispersal

Rethinking soil water repellency and its management

Soil water repellency (SWR) is a widespread challenge to plant establishment and growth. Despite considerable research, it remains a recalcitrant problem for which few alleviation technologies or solutions have been developed. Previous research has focused on SWR as a problem to be overcome, however, it is an inherent feature of many native ecosystems where it contributes to ecosystem functions. Therefore, we propose a shift in the way SWR is perceived in agriculture and in ecological restoration, from a problem to be solved, to an opportunity to be harnessed. A new focus on potential ecological benefits of SWR is particularly timely given increasing incidence, frequency and severity of hotter droughts in many regions of the world. Our new way of conceptualising SWR seeks to understand how SWR can be temporarily alleviated at a micro-scale to successfully establish plants, and then harnessed in the longer term and at larger spatial scales to enhance soil water storage to act as a “drought-proofing” tool for plant survival in water-limited soils. For this to occur, we suggest research focusing on the alignment of physico-chemical and microbial properties and dynamics of SWR and, based on this mechanistic understanding, create products and interventions to improve success of plant establishment in agriculture, restoration and conservation contexts. In this paper, we outline the rationale for a new way of conceptualising SWR, and the research priorities needed to fill critical knowledge gaps in order to harness the ecological benefits from managing SWR

The genomics of heart failure: design and rationale of the HERMES consortium

AIMS: The HERMES (HEart failure Molecular Epidemiology for Therapeutic targetS) consortium aims to identify the genomic and molecular basis of heart failure. METHODS AND RESULTS: The consortium currently includes 51 studies from 11 countries, including 68 157 heart failure cases and 949 888 controls, with data on heart failure events and prognosis. All studies collected biological samples and performed genome-wide genotyping of common genetic variants. The enrolment of subjects into participating studies ranged from 1948 to the present day, and the median follow-up following heart failure diagnosis ranged from 2 to 116 months. Forty-nine of 51 individual studies enrolled participants of both sexes; in these studies, participants with heart failure were predominantly male (34–90%). The mean age at diagnosis or ascertainment across all studies ranged from 54 to 84 years. Based on the aggregate sample, we estimated 80% power to genetic variant associations with risk of heart failure with an odds ratio of ≥1.10 for common variants (allele frequency ≥ 0.05) and ≥1.20 for low-frequency variants (allele frequency 0.01–0.05) at P < 5 × 10^{-8} under an additive genetic model. CONCLUSIONS: HERMES is a global collaboration aiming to (i) identify the genetic determinants of heart failure; (ii) generate insights into the causal pathways leading to heart failure and enable genetic approaches to target prioritization; and (iii) develop genomic tools for disease stratification and risk prediction

The genomics of heart failure: design and rationale of the HERMES consortium

Aims The HERMES (HEart failure Molecular Epidemiology for Therapeutic targets) consortium aims to identify the genomic and molecular basis of heart failure.Methods and results The consortium currently includes 51 studies from 11 countries, including 68 157 heart failure cases and 949 888 controls, with data on heart failure events and prognosis. All studies collected biological samples and performed genome-wide genotyping of common genetic variants. The enrolment of subjects into participating studies ranged from 1948 to the present day, and the median follow-up following heart failure diagnosis ranged from 2 to 116 months. Forty-nine of 51 individual studies enrolled participants of both sexes; in these studies, participants with heart failure were predominantly male (34-90%). The mean age at diagnosis or ascertainment across all studies ranged from 54 to 84 years. Based on the aggregate sample, we estimated 80% power to genetic variant associations with risk of heart failure with an odds ratio of >1.10 for common variants (allele frequency > 0.05) and >1.20 for low-frequency variants (allele frequency 0.01-0.05) at P < 5 x 10(-8) under an additive genetic model.Conclusions HERMES is a global collaboration aiming to (i) identify the genetic determinants of heart failure; (ii) generate insights into the causal pathways leading to heart failure and enable genetic approaches to target prioritization; and (iii) develop genomic tools for disease stratification and risk prediction.Cardiolog

The Promise and Problems of Organizational Culture: CEO Personality, Culture, and Firm Performance

Studies of organizational culture are almost always based on two assumptions: (a) Senior leaders are the prime determinant of the culture, and (b) culture is related to consequential organizational outcomes. Although intuitively reasonable and often accepted as fact, the empirical evidence for these is surprisingly thin, and the results are quite mixed. Almost no research has jointly investigated these assumptions and how they are linked. The purpose of this article is to empirically link CEO personality to culture and organizational culture to objective measures of firm performance. Using data from respondents in 32 high-technology companies, we show that CEO personality affects a firm’s culture and that culture is subsequently related to a broad set of organizational outcomes including a firm’s financial performance (revenue growth, Tobin’s Q), reputation, analysts’ stock recommendations, and employee attitudes. We discuss the implications of these findings for future research on organizational culture

Parsing organizational culture: How the norm for adaptability influences the relationship between culture consensus and financial performance in high-technology firms

The relationship between organizational culture and financial performance remains elusive even though researchers have studied it for some time. Early research suggested that a strong culture that aligns members' behavior with organizational objectives boosts financial performance. A more recent view is that, because strong cultures promote adherence to routines and behavioral uniformity, they are less effective in dynamic environments. We suggest that the relationship between culture and performance can be reconciled by recognizing that culture encompasses three components: (1) the content of norms (norm content); (2) how widely members agree about norms (culture consensus); and (3) how intensely organizational members hold particular norms (norm intensity). We hypothesize that "strong cultures"-where a high consensus exists among members across a broad set of culture norms-can contribute to better financial performance even in dynamic environments if norm content intensely emphasizes adaptability. We test this hypothesis in a sample of large firms in the high-technology industry. Firms characterized by higher culture consensus and intensity about adaptability performed better three years later than did those characterized by lower consensus, lower intensity about adaptability, or both. We discuss how parsing culture into content, consensus, and intensity advances theoretical and empirical understanding of the culture-performance relationship. © 2014 John Wiley &amp; Sons, Ltd

Parsing organizational culture: How the norm for adaptability influences the relationship between culture consensus and financial performance in high-technology firms

The relationship between organizational culture and financial performance remains elusive even though researchers have studied it for some time. Early research suggested that a strong culture that aligns members' behavior with organizational objectives boosts financial performance. A more recent view is that, because strong cultures promote adherence to routines and behavioral uniformity, they are less effective in dynamic environments. We suggest that the relationship between culture and performance can be reconciled by recognizing that culture encompasses three components: (1) the content of norms (norm content); (2) how widely members agree about norms (culture consensus); and (3) how intensely organizational members hold particular norms (norm intensity). We hypothesize that "strong cultures"-where a high consensus exists among members across a broad set of culture norms-can contribute to better financial performance even in dynamic environments if norm content intensely emphasizes adaptability. We test this hypothesis in a sample of large firms in the high-technology industry. Firms characterized by higher culture consensus and intensity about adaptability performed better three years later than did those characterized by lower consensus, lower intensity about adaptability, or both. We discuss how parsing culture into content, consensus, and intensity advances theoretical and empirical understanding of the culture-performance relationship. © 2014 John Wiley &amp; Sons, Ltd

The Promise and Problems of Organizational Culture: CEO Personality, Culture, and Firm Performance

Studies of organizational culture are almost always based on two assumptions: (a) Senior leaders are the prime determinant of the culture, and (b) culture is related to consequential organizational outcomes. Although intuitively reasonable and often accepted as fact, the empirical evidence for these is surprisingly thin, and the results are quite mixed. Almost no research has jointly investigated these assumptions and how they are linked. The purpose of this article is to empirically link CEO personality to culture and organizational culture to objective measures of firm performance. Using data from respondents in 32 high-technology companies, we show that CEO personality affects a firm’s culture and that culture is subsequently related to a broad set of organizational outcomes including a firm’s financial performance (revenue growth, Tobin’s Q), reputation, analysts’ stock recommendations, and employee attitudes. We discuss the implications of these findings for future research on organizational culture