Overlap Concentration and the Effect of Macromolecular Crowding on Citrate Synthase Activity.

Although it is well-known that the environment of mitochondria is a densely packed network of macromolecules, the kinetics of the essential metabolic enzyme, citrate synthase, has been studied only under dilute conditions. To understand how this crowded environment impacts the behavior of citrate synthase, Michaelis-Menten kinetics were measured spectrophotometrically in the presence of synthetic crowders as a function of size, concentration, and identity. The largest factor contributing to crowding effects was the overlap concentration (c*), the concentration above which polymers begin to interact. The presence of the crowder dextran decreased the maximum rate of the reaction by ∼20% in the dilute regime (c*) regardless of polymer size. The disparate effects observed from different crowding agents of similar size also reveal the importance of transient interactions from crowding.

Performance of fibrosis prediction scores in paediatric non-alcoholic fatty liver disease.

AIM: Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in children. The phenotype of NAFLD varies widely, and non-invasive predictors of disease severity are scarce and are needed to tailor clinical management. METHODS: We compared liver fibrosis by histology with proposed non-invasive predictors of fibrosis, including alanine transaminase (ALT), aspartate transaminase (AST), AST/ALT ratio, AST to platelet ratio index, fibrosis-4, paediatric NAFLD fibrosis index and paediatric NAFLD fibrosis score. RESULTS: The area under the curve of scores obtained while predicting fibrosis in children with NAFLD ranged from 0.51 to 0.67. CONCLUSION: The tested non-invasive fibrosis scoring systems, some of which were originally designed for adult populations, did not adequately predict fibrosis in a paediatric cohort. Further development of risk prediction scores in children are needed for the management of paediatric patients and will likely need to be developed within a large paediatric data set in order to improve specificity and sensitivity.

Mass Media and the Contagion of Fear: The Case of Ebola in America.

BACKGROUND: In the weeks following the first imported case of Ebola in the U. S. on September 29, 2014, coverage of the very limited outbreak dominated the news media, in a manner quite disproportionate to the actual threat to national public health; by the end of October, 2014, there were only four laboratory confirmed cases of Ebola in the entire nation. Public interest in these events was high, as reflected in the millions of Ebola-related Internet searches and tweets performed in the month following the first confirmed case. Use of trending Internet searches and tweets has been proposed in the past for real-time prediction of outbreaks (a field referred to as "digital epidemiology"), but accounting for the biases of public panic has been problematic. In the case of the limited U. S. Ebola outbreak, we know that the Ebola-related searches and tweets originating the U. S. during the outbreak were due only to public interest or panic, providing an unprecedented means to determine how these dynamics affect such data, and how news media may be driving these trends. METHODOLOGY: We examine daily Ebola-related Internet search and Twitter data in the U. S. during the six week period ending Oct 31, 2014. TV news coverage data were obtained from the daily number of Ebola-related news videos appearing on two major news networks. We fit the parameters of a mathematical contagion model to the data to determine if the news coverage was a significant factor in the temporal patterns in Ebola-related Internet and Twitter data. CONCLUSIONS: We find significant evidence of contagion, with each Ebola-related news video inspiring tens of thousands of Ebola-related tweets and Internet searches. Between 65% to 76% of the variance in all samples is described by the news media contagion model.