Cryopreservation and re-culture of a 2.3 litre biomass for use in a bioartificial liver device

For large and complex tissue engineered constructs to be available on demand, long term storage using methods, such as cryopreservation, are essential. This study optimised parameters such as excess media concentration and warming rates and used the findings to enable the successful cryopreservation of 2.3 litres of alginate encapsulated liver cell spheroids. This volume of biomass is typical of those required for successful treatment of Acute Liver Failure using our Bioartificial Liver Device. Adding a buffer of medium above the biomass, as well as slow (0.6°C/min) warming rates was found to give the best results, so long as the warming through the equilibrium melting temperature was rapid. After 72 h post thaw-culture, viable cell number, glucose consumption, lactate production, and alpha-fetoprotein production had recovered to pre-freeze values in the 2.3 litre biomass (1.00 ± 0.05, 1.19 ± 0.10, 1.23 ± 0.18, 2.03 ± 0.04 per ml biomass of the pre-cryopreservation values respectively). It was also shown that further improvements in warming rates of the biomass could reduce recovery time to < 48 h. This is the first example of a biomass of this volume being successfully cryopreserved in a single cassette and re-cultured. It demonstrates that a bioartificial liver device can be cryopreserved, and has wider applications to scale-up large volume cryopreservation

Impact of Storage at -80°C on Encapsulated Liver Spheroids After Liquid Nitrogen Storage

For many bioengineered tissues to have practical clinical application, cryopreservation for use on demand is essential. This study examined different thermal histories on warming and short holding periods at different subzero temperatures on subsequent functional recoveries of alginate encapsulated liver spheroids (ELS) for use in a bioartificial liver device. This mimicked transport at liquid nitrogen (-196°C) or dry ice (∼-80°C) temperatures. Holding at -80°C on warming after -196°C storage resulted in ELS expressing significant (p < 0.001) damage compared with direct thaw from liquid nitrogen, with viable cell number falling from 74.0 ± 8.4 million viable cells/mL without -80°C storage to 1.9 ± 0.6 million viable cells/mL 72 h post-thaw after 8 days storage at -80°C. Even 1 day at -80°C after -196°C storage resulted in lower viability (down 21% 24 h post-thaw), viable cell count (down 29% 24 h post-thaw), glucose, and alpha-1-fetoprotein production (reduced by 59% and 95% 24 h from 1 day post-thaw, respectively). Storage at -80°C was determined to be harmful only during the warming cycle. Chemical measurements of the alginate component of ELS were unchanged by cryogenic exposure in either condition

Forest Disturbance Detection and Aboveground Biomass Modeling Using Moderate-Resolution, Time-Series Satellite Imagery

Human-induced and natural disturbances are an important feature of forest ecosystems. Disturbances influence forest structure and composition and can impact crucial ecosystem services. However, deriving spatially explicit estimates of past forest disturbance across a large region can prove challenging. Researchers have recognized that remote sensing is an important tool for monitoring forest ecosystems and mapping land use and land cover change. One of the most important sources of remotely sensed imagery is the United States Geologic Survey’s Landsat program which has continuously acquired earth observations since 1972. This repository of imagery has the spatial, spectral, and temporal resolution necessary to produce maps of disturbance which are meaningful for the analysis of forested ecosystems. In this analysis, we utilize the imagery from the Landsat archive to produce maps of forest disturbance from 1985 to 2017 for the New England states and the Canadian Maritime provinces. The change detection maps were developed using stacked generalization, a modeling technique that fuses the outputs of an ensemble of individual change-detection algorithms through the use of a secondary classifier. To better understand the error associated with these classifications, we quantified the spectral characteristics associated with different harvesting practices. Using two case studies, the 1998 ice storm and the 2016 gypsy moth outbreak in southern New England, we performed experiments to examine how the stacked generalization framework can be utilized to increase the accuracy of disturbance maps following large-scale natural disturbances. The change detection maps developed in this analysis possessed a 98.7% overall accuracy and a 27.5% balance of the errors of omission and commission. Our results indicated that adjusting the probability threshold associated with the secondary classifier in the stacked generalization framework increase the spatial coherence of disturbance patches and better capture the low- to moderate-severity disturbances. Using the maps of disturbance for the New England states and Maritime Provinces, we derived metrics describing the spectral change magnitude, timing, and percent spectral recovery across the study region. Recent research has found that including metrics of disturbance and recovery processes, derived from the analysis of time-series satellite imagery, can improve the accuracy of AGB models. However, these studies have largely been conducted in regions with relatively homogenous forest composition and structure and disturbance regimes dominated by stand-replacing disturbances. This analysis expands upon the existing literature by exploring how disturbance and recovery metrics can improve the predictions of AGB models in a heterogeneous landscape with a complex land-use history. Gradient boosting models, a sophisticated machine learning technique, were used to produce regional AGB models using spectral, disturbance, and environmental (e.g., topographic, climatological, etc.) metrics. Additionally, we explore how adjusting the rate of mapped disturbance through modifications to the class-inclusion rate associated with the secondary classifier can impact estimates of AGB. We conclude that landscape heterogeneity, as well as the general lack of stand-replacing disturbances, negatively impacts the predictive utility of disturbance and recovery metrics for modeling AGB

Radius and chirality dependent conformation of polymer molecule at nanotube interface

Temperature dependent conformations of linear polymer molecules adsorbed at carbon nanotube (CNT) interfaces are investigated through molecule dynamics simulations. Model polyethylene (PE) molecules are shown to have selective conformations on CNT surface, controlled by atomic structures of CNT lattice and geometric coiling energy. PE molecules form entropy driven assembly domains, and their preferred wrapping angles around large radius CNT (40, 40) reflect the molecule configurations with energy minimums on a graphite plane. While PE molecules prefer wrapping on small radius armchair CNT (5, 5) predominantly at low temperatures, their configurations are shifted to larger wrapping angle ones on a similar radius zigzag CNT (10, 0). A nematic transformation around 280 K is identified through Landau-deGennes theory, with molecule aligning along tube axis in extended conformationsComment: 19 pages, 7 figure2, submitted to journa

Modulation of Mcl-1 sensitizes glioblastoma to TRAIL-induced apoptosis

Glioblastoma (GBM) is the most aggressive form of primary brain tumour, with dismal patient outcome. Treatment failure is associated with intrinsic or acquired apoptosis resistance and the presence of a highly tumourigenic subpopulation of cancer cells called GBM stem cells. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) has emerged as a promising novel therapy for some treatment-resistant tumours but unfortunately GBM can be completely resistant to TRAIL monotherapy. In this study, we identified Mcl-1, an anti-apoptotic Bcl-2 family member, as a critical player involved in determining the sensitivity of GBM to TRAIL-induced apoptosis. Effective targeting of Mcl-1 in TRAIL resistant GBM cells, either by gene silencing technology or by treatment with R-roscovitine, a cyclin-dependent kinase inhibitor that targets Mcl-1, was demonstrated to augment sensitivity to TRAIL, both within GBM cells grown as monolayers and in a 3D tumour model. Finally, we highlight that two separate pathways are activated during the apoptotic death of GBM cells treated with a combination of TRAIL and R-roscovitine, one which leads to caspase-8 and caspase-3 activation and a second pathway, involving a Mcl-1:Noxa axis. In conclusion, our study demonstrates that R-roscovitine in combination with TRAIL presents a promising novel strategy to trigger cell death pathways in glioblastoma. Electronic supplementary material The online version of this article (doi:10.1007/s10495-013-0935-2) contains supplementary material, which is available to authorized users

Effect of Palmitic Acid on the Electrical Conductivity of Carbon Nanotubes−Epoxy Resin Composites

We found that the palmitic acid allows an efficient dispersion of carbon nanotubes in the epoxy matrix. We have set up an experimental protocol in order to enhance the CNTs dispersion in epoxy resin. Electrical conductivity is optimal using a 1:1 CNTs to palmitic acid weight ratio. The associated percolation threshold is found between 0.05 and 0.1 wt % CNTs, i.e., between 0.03 and 0.06 vol %. The SEM image shows essentially individual CNTs which is inagreement with conductivity measurements. In comparison with composites without palmitic acid, the use of palmitic acid improves the electrical properties of CNTs-epoxy resin composites

Latrepirdine is a potent activator of AMP-activated protein kinase and reduces neuronal excitability.

Latrepirdine/Dimebon is a small-molecule compound with attributed neurocognitive-enhancing activities, which has recently been tested in clinical trials for the treatment of Alzheimer\u27s and Huntington\u27s disease. Latrepirdine has been suggested to be a neuroprotective agent that increases mitochondrial function, however the molecular mechanisms underlying these activities have remained elusive. We here demonstrate that latrepirdine, at (sub)nanomolar concentrations (0.1 nM), activates the energy sensor AMP-activated protein kinase (AMPK). Treatment of primary neurons with latrepirdine increased intracellular ATP levels and glucose transporter 3 translocation to the plasma membrane. Latrepirdine also increased mitochondrial uptake of the voltage-sensitive probe TMRM. Gene silencing of AMPKα or its upstream kinases, LKB1 and CaMKKβ, inhibited this effect. However, studies using the plasma membrane potential indicator DisBAC2(3) demonstrated that the effects of latrepirdine on TMRM uptake were largely mediated by plasma membrane hyperpolarization, precluding a purely \u27mitochondrial\u27 mechanism of action. In line with a stabilizing effect of latrepirdine on plasma membrane potential, pretreatment with latrepirdine reduced spontaneous Ca(2+) oscillations as well as glutamate-induced Ca(2+) increases in primary neurons, and protected neurons against glutamate toxicity. In conclusion, our experiments demonstrate that latrepirdine is a potent activator of AMPK, and suggest that one of the main pharmacological activities of latrepirdine is a reduction in neuronal excitability

Core components for effective infection prevention and control programmes: new WHO evidence-based recommendations

Abstract Health care-associated infections (HAI) are a major public health problem with a significant impact on morbidity, mortality and quality of life. They represent also an important economic burden to health systems worldwide. However, a large proportion of HAI are preventable through effective infection prevention and control (IPC) measures. Improvements in IPC at the national and facility level are critical for the successful containment of antimicrobial resistance and the prevention of HAI, including outbreaks of highly transmissible diseases through high quality care within the context of universal health coverage. Given the limited availability of IPC evidence-based guidance and standards, the World Health Organization (WHO) decided to prioritize the development of global recommendations on the core components of effective IPC programmes both at the national and acute health care facility level, based on systematic literature reviews and expert consensus. The aim of the guideline development process was to identify the evidence and evaluate its quality, consider patient values and preferences, resource implications, and the feasibility and acceptability of the recommendations. As a result, 11 recommendations and three good practice statements are presented here, including a summary of the supporting evidence, and form the substance of a new WHO IPC guideline

Contribution of Cystine-Glutamate Antiporters to the Psychotomimetic Effects of Phencyclidine

Altered glutamate signaling contributes to a myriad of neural disorders, including schizophrenia. While synaptic levels are intensely studied, nonvesicular release mechanisms, including cystine–glutamate exchange, maintain high steady-state glutamate levels in the extrasynaptic space. The existence of extrasynaptic receptors, including metabotropic group II glutamate receptors (mGluR), pose nonvesicular release mechanisms as unrecognized targets capable of contributing to pathological glutamate signaling. We tested the hypothesis that activation of cystine–glutamate antiporters using the cysteine prodrug N-acetylcysteine would blunt psychotomimetic effects in the rodent phencyclidine (PCP) model of schizophrenia. First, we demonstrate that PCP elevates extracellular glutamate in the prefrontal cortex, an effect that is blocked by N-acetylcysteine pretreatment. To determine the relevance of the above finding, we assessed social interaction and found that N-acetylcysteine reverses social withdrawal produced by repeated PCP. In a separate paradigm, acute PCP resulted in working memory deficits assessed using a discrete trial t-maze task, and this effect was also reversed by N-acetylcysteine pretreatment. The capacity of N-acetylcysteine to restore working memory was blocked by infusion of the cystine–glutamate antiporter inhibitor (S)-4-carboxyphenylglycine into the prefrontal cortex or systemic administration of the group II mGluR antagonist LY341495 indicating that the effects of N-acetylcysteine requires cystine–glutamate exchange and group II mGluR activation. Finally, protein levels from postmortem tissue obtained from schizophrenic patients revealed significant changes in the level of xCT, the active subunit for cystine–glutamate exchange, in the dorsolateral prefrontal cortex. These data advance cystine–glutamate antiporters as novel targets capable of reversing the psychotomimetic effects of PCP

Observing eruptions of gas-rich, compressible magmas from space

Observations of volcanoes from space are a critical component of volcano monitoring, but we lack quantitative integrated models to interpret them. The atmospheric sulfur yields of eruptions are variable and not well correlated with eruption magnitude and for many eruptions the volume of erupted material is much greater than the subsurface volume change inferred from ground displacements. Up to now, these observations have been treated independently, but they are fundamentally linked. If magmas are vapor-saturated prior to eruption, bubbles cause the magma to become more compressible, resulting in muted ground displacements. The bubbles contain the sulfur-bearing vapor injected into the atmosphere during eruptions. Here we present a model that allows the inferred volume change of the reservoir and the sulfur mass loading to be predicted as a function of reservoir depth and the magma ’s oxidation state and volatile content, which is consistent with the array of natural data.The authors gratefully acknowledge the support of the Deep Carbon Observatory and DECADE (part of the Reservoirs and Fluxes community), the Natural Environment Research Council (NERC) Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics (CO MET), the British Geological Survey and the University of Cambridge Isaac Newton Trust