Development of a novel microfluidic device for long-term in situ monitoring of live cells in 3-dimensional matrices.

Using the latest innovations in microfabrication technology, 3-dimensional microfluidic cell culture systems have been developed as an attractive alternative to traditional 2-dimensional culturing systems as a model for long-term microscale cell-based research. Most microfluidic systems are based on the embedding of cells in hydrogels. However, physiologically realistic conditions based on hydrogels are difficult to obtain and the systems are often too complicated.

Retroviral assembly and budding occur through an actin-driven mechanism.

The assembly and budding of a new virus is a fundamental step in retroviral replication. Yet, despite substantial progress in the structural and biochemical characterization of retroviral budding, the underlying physical mechanism remains poorly understood, particularly with respect to the mechanism by which the virus overcomes the energy barrier associated with the formation of high membrane curvature during viral budding. Using atomic force, fluorescence, and transmission electron microscopy, we find that both human immunodeficiency virus and Moloney murine leukemia virus remodel the actin cytoskeleton of their host.

Directly monitoring individual retrovirus budding events using atomic force microscopy.

Retrovirus budding is a key step in the virus replication cycle. Nonetheless, very little is known about the underlying mechanism of budding, primarily due to technical limitations preventing visualization of bud formation in real time. Methods capable of monitoring budding dynamics suffer from insufficient resolution, whereas other methods, such as electron microscopy, do not have the ability to operate under physiological conditions.

Mechanical properties of murine leukemia virus particles: effect of maturation.

After budding from the host cell, retroviruses undergo a process of internal reorganization called maturation, which is prerequisite to infectivity. Viral maturation is accompanied by dramatic morphological changes, which are poorly understood in physical/mechanistic terms. Here, we study the mechanical properties of live mature and immature murine leukemia virus particles by indentation-type experiments conducted with an atomic force microscope tip.

A mutation in a CD44 variant of inflammatory cells enhances the mitogenic interaction of FGF with its receptor.

Synovial fluid cells from joints of rheumatoid arthritis (RA) patients express a novel variant of CD44 (designated CD44vRA), encoding an extra trinucleotide (CAG) transcribed from intronic sequences flanking a variant exon. The CD44vRA mutant was detected in 23 out of 30 RA patients. CD44-negative Namalwa cells transfected with CD44vRA cDNA or with CD44v3-v10 (CD44vRA wild type) cDNA bound FGF-2 to an equal extent via their associated heparan sulfate chains.