Deposition of aggregated Aβ peptide in the brain is one of the major hallmarks of Alzheimer's disease. Using a combination of two structurally different, but related, hypersensitive fluorescent amyloid markers, LCOs, reporting on separate ultrastructural elements, we show that conformational rearrangement occurs within Aβ plaques of transgenic mouse models as the animals age. This important mechanistic insight should aid the design and evaluation of experiments currently using plaque load as readout.

Key Points• IL-32 is a proinflammatory cytokine expressed by plasma cells in a subset of MM patients, and high expression correlates with poor survival.• IL-32 is induced by hypoxia and secreted from MM cells in EVs that promote bone destruction.

No abstract

Amyloid plaques composed of fibrillar Amyloid-β (Aβ) are hallmarks of Alzheimer's disease. However, Aβ fibrils are morphologically heterogeneous. Conformation sensitive luminescent conjugated oligothiophenes (LCOs) are versatile tools for monitoring such fibril polymorphism in vivo and in vitro. Biophysical methods applied on in vitro generated Aβ fibrils, stained with LCOs with different binding and fluorescence properties, can be used to characterize the Aβ fibrillation in depth, far beyond that possible for in vivo generated amyloid plaques. In this study, in vitro fibrillation of the Aβ1-40 peptide was monitored by time-lapse transmission electron microscopy, LCO fluorescence, and atomic force microscopy. Differences in the LCO binding in combination with nanoscale imaging revealed that spectral variation correlated with fibrils transforming from solitary filaments (Ø~2.5 nm) into higher order bundled structures (Ø~5 nm). These detailed in vitro experiments can be used to derive data that reflects the heterogeneity of in vivo generated Aβ plaques observed by LCO fluorescence. Our work provides new structural basis for targeted drug design and molecular probe development for amyloid imaging.

Extracellular micro- and nano-scale membrane vesicles produced by different cells are recognised as an essential entity of physiological fluids in a variety of organisms and function as mediators of intercellular communication employed for the regulation of multiple systemic and local processes. In the last decade, an exponential amount of experimental work was dedicated to exploring the biogenesis and secretion mechanisms, physiological and pathological functions and potential applications of the extracellular vesicles (EVs). Noteworthy is the large heterogeneity of in vitro and in vivo models applied, technical approaches developed in these studies and the diversity of designations assigned to different or similar types of EVs. Hence, there is a clear necessity for a uniform nomenclature and standardisation of methods to isolate and characterise these vesicles. In April 2012, the first meeting of the International Society for Extracellular Vesicles (ISEV) took place bringing together this exponentially grown scientific community. The University of Gothenburg (Krefting Research Centre) together with the Interim Board of the Society created in September 2011 (Jan Lötvall, Clotilde Théry, Xandra Breakefield, Marca Wauben, Yong Song Gho, Lawrence Rajendran, Graça Raposo, Douglas Taylor, Margareta Sjöstrand and Esbjörn Telemo) organised this fantastic event that counted 488 registered and contributing participants. This meeting report provides a retrospective summary of the broad spectrum of ISEV-2012 sessions. Again, we emphasise novel findings, discussions and decisions met by the community during the meeting.

Two different conformational isoforms or amyloid strains of insulin with different cytotoxic capacity have been described previously. Herein these filamentous and fibrillar amyloid states of insulin were investigated using biophysical and spectroscopic techniques in combination with luminescent conjugated oligothiophenes (LCO). This new class of fluorescent probes has a well defined molecular structure with a distinct number of thiophene units that can adopt different dihedral angles depending on its binding site to an amyloid structure. Based on data from surface charge, hydrophobicity, fluorescence spectroscopy and imaging, along with atomic force microscopy (AFM), we deduce the ultrastructure and fluorescent properties of LCO stained insulin fibrils and filaments. Combined total internal reflection fluorescence microscopy (TIRFM) and AFM revealed rigid linear fibrous assemblies of fibrils whereas filaments showed a short curvilinear morphology which assemble into cloudy deposits. All studied LCOs bound to the filaments afforded more blue-shifted excitation and emission spectra in contrast to those corresponding to the fibril indicating a different LCO binding site, which was also supported by less efficient hydrophobic probe binding. Taken together, the multi-tool approach used here indicates the power of ultrastructure identification applying AFM together with LCO fluorescence interrogation, including TIRFM, to resolve structural differences between amyloid states.

Ionizing radiation is responsible for production of double-strand breaks (DSBs) in a DNA structure. In contrast to sparsely ionizing radiation, densely ionizing radiation produces DSBs that are non-randomly distributed along the DNA molecule and can form clusters of various size. The paper discusses minimalistic models that describe observable patterns of fragment length in DNA segments irradiated with heavy ions and applies the formalism to interpret the recent experimental data collected by use of atomic force microscope (AFM).

Double-strand breaks (DSBs) are the most critical radiation-induced lesions, because they result in the fragmentation of the DNA molecule and because a single unrepaired DSB may lead to cell death. We present the results of radiation-induced fragmentation of plasmid DNA analyzed by atomic force microscopy (AFM) to allow the visualization of individual DNA molecules. Linear PhiX174 plasmid DNA was exposed to a wide range of doses of low-LET X rays and high-LET carbon, nickel and uranium ions. The induced DNA fragments were detected and measured based on the recorded AFM images and fragment length distributions were derived for each radiation type and dose. The results show a dose- and radiation type-dependent DNA fragmentation with a significantly larger fraction of short fragments produced by high-LET radiation compared to X rays. This can be considered as experimental evidence of DSB clustering due to inhomogeneous energy deposition at the level of the plasmid DNA molecule. Additionally, the experimentally derived fragment profiles were compared and found to be in agreement with the prediction of a model simulating the fragmentation of DNA molecules induced by radiation.