Selective gene silencing by viral delivery of short hairpin RNA

RNA interference (RNAi) technology has not only become a powerful tool for functional genomics, but also allows rapid drug target discovery and in vitro validation of these targets in cell culture. Furthermore, RNAi represents a promising novel therapeutic option for treating human diseases, in particular cancer. Selective gene silencing by RNAi can be achieved essentially by two nucleic acid based methods: i) cytoplasmic delivery of short double-stranded (ds) interfering RNA oligonucleotides (siRNA), where the gene silencing effect is only transient in nature, and possibly not suitable for all applications; or ii) nuclear delivery of gene expression cassettes that express short hairpin RNA (shRNA), which are processed like endogenous interfering RNA and lead to stable gene down-regulation. Both processes involve the use of nucleic acid based drugs, which are highly charged and do not cross cell membranes by free diffusion. Therefore, in vivo delivery of RNAi therapeutics must use technology that enables the RNAi therapeutic to traverse biological membrane barriers in vivo. Viruses and the vectors derived from them carry out precisely this task and have become a major delivery system for shRNA. Here, we summarize and compare different currently used viral delivery systems, give examples of in vivo applications, and indicate trends for new developments, such as replicating viruses for shRNA delivery to cancer cells

Characterization of mitochondrial neutral protease activity and the response of lysosomal enzymes to clofibrate feeding in rat liver

The phosphate-inhibitable neutral protease activity of the heavy mitochondrial fraction of rat liver is of lysosomal origin. The activity is essentially due to the thiol proteinases of the lysosomes. Digitonin treatment of the mitochondrial fraction results in the release of about 85 per cent of the neutral protease activity and the residual activity has an alkaline pH optimum and is not inhibited by phosphate. Clofibrate feeding at 0.5 per cent level in the diet results in enhanced levels of lysosomal enzymes. The increase is however restricted to the lysosome-rich fraction such that the activities associated with the heavy mitochondrial fraction show a significant decrease. It is suggested that clofibrate inhibits engulfment of mitochondria by lysosomes and this results in enhanced mitochondrial protein content

Sharing knowledge in digital ecosystems using semantic multimedia big data

The use of formal representations has a basic importance in the era of big data. This need is more evident in the context of multimedia big data due to the intrinsic complexity of this type of data. Furthermore, the relationships between objects should be clearly expressed and formalized to give the right meaning to the correlation of data. For this reason the design of formal models to represent and manage information is a necessary task to implement intelligent information systems. Approaches based on the semantic web need to improve the data models that are the basis for implementing big data applications. Using these models, data and information visualization becomes an intrinsic and strategic task for the analysis and exploration of multimedia Big Data. In this article we propose the use of a semantic approach to formalize the structure of a multimedia Big Data model. Moreover, the identification of multimodal features to represent concepts and linguistic-semantic properties to relate them is an effective way to bridge the gap between target semantic classes and low-level multimedia descriptors. The proposed model has been implemented in a NoSQL graph database populated by different knowledge sources. We explore a visualization strategy of this large knowledge base and we present and discuss a case study for sharing information represented by our model according to a peer-to-peer(P2P) architecture. In this digital ecosystem, agents (e.g. machines, intelligent systems, robots,..) act like interconnected peers exchanging and delivering knowledge with each other