9 research outputs found
Cellular transfer and AFM imaging of cancer cells using Bioimprint
A technique for permanently capturing a replica impression of biological cells has been developed to facilitate analysis using nanometer resolution imaging tools, namely the atomic force microscope (AFM). The method, termed Bioimprintâą, creates a permanent cell 'footprint' in a non-biohazardous Poly (dimethylsiloxane) (PDMS) polymer composite. The transfer of nanometer scale biological information is presented as an alternative imaging technique at a resolution beyond that of optical microscopy. By transferring cell topology into a rigid medium more suited for AFM imaging, many of the limitations associated with scanning of biological specimens can be overcome. Potential for this technique is demonstrated by analyzing Bioimprintâą replicas created from human endometrial cancer cells. The high resolution transfer of this process is further detailed by imaging membrane morphological structures consistent with exocytosis. The integration of soft lithography to replicate biological materials presents an enhanced method for the study of biological systems at the nanoscale
Species-specific, pan-European diameter increment models based on data of 2.3 million trees
ResearchBackground: Over the last decades, many forest simulators have been developed for the forests of individual
European countries. The underlying growth models are usually based on national datasets of varying size, obtained
from National Forest Inventories or from long-term research plots. Many of these models include country- and
location-specific predictors, such as site quality indices that may aggregate climate, soil properties and topography
effects. Consequently, it is not sensible to compare such models among countries, and it is often impossible to
apply models outside the region or country they were developed for. However, there is a clear need for more
generically applicable but still locally accurate and climate sensitive simulators at the European scale, which requires
the development of models that are applicable across the European continent. The purpose of this study is to
develop tree diameter increment models that are applicable at the European scale, but still locally accurate. We
compiled and used a dataset of diameter increment observations of over 2.3 million trees from 10 National Forest
Inventories in Europe and a set of 99 potential explanatory variables covering forest structure, weather, climate, soil
and nutrient deposition.
Results: Diameter increment models are presented for 20 species/species groups. Selection of explanatory variables
was done using a combination of forward and backward selection methods. The explained variance ranged from
10% to 53% depending on the species. Variables related to forest structure (basal area of the stand and relative size
of the tree) contributed most to the explained variance, but environmental variables were important to account for
spatial patterns. The type of environmental variables included differed greatly among species.
Conclusions: The presented diameter increment models are the first of their kind that are applicable at the
European scale. This is an important step towards the development of a new generation of forest development
simulators that can be applied at the European scale, but that are sensitive to variations in growing conditions and
applicable to a wider range of management systems than before. This allows European scale but detailed analyses
concerning topics like CO2 sequestration, wood mobilisation, long term impact of management, etcinfo:eu-repo/semantics/publishedVersio
Novel Small-Molecule Inhibitors of Hepatitis C Virus Entry Block Viral Spread and Promote Viral Clearance in Cell Culture
Combinations of direct-acting anti-virals offer the potential to improve the efficacy, tolerability and duration of the current treatment regimen for hepatitis C virus (HCV) infection. Viral entry represents a distinct therapeutic target that has been validated clinically for a number of pathogenic viruses. To discover novel inhibitors of HCV entry, we conducted a high throughput screen of a proprietary small-molecule compound library using HCV pseudoviral particle (HCVpp) technology. We independently discovered and optimized a series of 1,3,5-triazine compounds that are potent, selective and non-cytotoxic inhibitors of HCV entry. Representative compounds fully suppress both cell-free virus and cell-to-cell spread of HCV in vitro. We demonstrate, for the first time, that long term treatment of an HCV cell culture with a potent entry inhibitor promotes sustained viral clearance in vitro. We have confirmed that a single amino acid variant, V719G, in the transmembrane domain of E2 is sufficient to confer resistance to multiple compounds from the triazine series. Resistance studies were extended by evaluating both the fusogenic properties and growth kinetics of drug-induced and natural amino acid variants in the HCVpp and HCV cell culture assays. Our results indicate that amino acid variations at position 719 incur a significant fitness penalty. Introduction of I719 into a genotype 1b envelope sequence did not affect HCV entry; however, the overall level of HCV replication was reduced compared to the parental genotype 1b/2a HCV strain. Consistent with these findings, I719 represents a significant fraction of the naturally occurring genotype 1b sequences. Importantly, I719, the most relevant natural polymorphism, did not significantly alter the susceptibility of HCV to the triazine compounds. The preclinical properties of these triazine compounds support further investigation of entry inhibitors as a potential novel therapy for HCV infection