In Vitro and In Vivo Effects of SerpinA1 on the Modulation of Transthyretin Proteolysis

Transthyretin (TTR) proteolysis has been recognized as a complementary mechanism contributing to transthyretin-related amyloidosis (ATTR amyloidosis). Accordingly, amyloid deposits can be composed mainly of full-length TTR or contain a mixture of both cleaved and full-length TTR, particularly in the heart. The fragmentation pattern at Lys48 suggests the involvement of a serine protease, such as plasmin. The most common TTR variant, TTR V30M, is susceptible to plasmin-mediated proteolysis, and the presence of TTR fragments facilitates TTR amyloidogenesis. Recent studies revealed that the serine protease inhibitor, SerpinA1, was differentially expressed in hepatocyte-like cells (HLCs) from ATTR patients. In this work, we evaluated the effects of SerpinA1 on in vitro and in vivo modulation of TTR V30M proteolysis, aggregation, and deposition. We found that plasmin-mediated TTR proteolysis and aggregation are partially inhibited by SerpinA1. Furthermore, in vivo downregulation of SerpinA1 increased TTR levels in mice plasma and deposition in the cardiac tissue of older animals. The presence of TTR fragments was observed in the heart of young and old mice but not in other tissues following SerpinA1 knockdown. Increased proteolytic activity, particularly plasmin activity, was detected in mice plasmas. Overall, our results indicate that SerpinA1 modulates TTR proteolysis and aggregation in vitro and in vivo.     

Neuroprotection Mediated by Human Blood Plasma in Mouse Hippocampal Slice Cultures and in Oxidatively Stressed Human Neurons

Neuroprotection from oxidative stress is critical during neuronal development and maintenance but also plays a major role in the pathogenesis and potential treatment of various neurological disorders and neurodegenerative diseases. Emerging evidence in the murine system suggests neuroprotective effects of blood plasma on the aged or diseased brain. However, little is known about plasma-mediated effects on human neurons. In the present study, we demonstrate the neuroprotective effect mediated by human plasma and the most abundant plasma–protein human serum albumin against oxidative stress in glutamatergic neurons differentiated from human neural crest-derived inferior turbinate stem cells. We observed a strong neuroprotective effect of human plasma and human serum albumin against oxidative stress-induced neuronal death on the single cell level, similar to the one mediated by tumor necrosis factor alpha. Moreover, we detected neuroprotection of plasma and human serum albumin against kainic acid-induced excitatory stress in ex vivo cultured mouse hippocampal tissue slices. The present study provides deeper insights into plasma-mediated neuroprotection ultimately resulting in the development of novel therapies for a variety of neurological and, in particular, neurodegenerative diseases.     

Optical trap stiffness in the presence and absence of spherical aberrations

Optical traps are commonly constructed with high-numerical-aperture objectives. Oil-immersion objectives suffer from spherical aberrations when used for imaging in aqueous solutions. The effect of spherical aberrations on trapping strength has been modeled by approximation, and only a few experimental results are available in the case of micrometer-sized particles. We present an experimental study of the dependence of lateral and axial optical-trap stiffness on focusing depth for polystyrene and silica beads of 2 microm diameter by using oil- and water-immersion objectives. We demonstrate a strong depth dependence of trap stiffness with the oil-immersion objective, whereas no depth dependence was observed with the water-immersion objective.     

Light scattering on Chebyshev particles of higher order

We present what we believe to be the first results of a light-scattering analysis on several Chebyshev particles characterized by higher orders. Chebyshev particles of comparatively lower orders were used in the past to study the effects of nonspherical but concave geometries in remote sensing applications. We will show that, based on the developed methodology, accurate results can also be obtained for particles of higher orders exhibiting a more pronounced surface waviness. The achieved results demonstrate that higher-order Chebyshev particles can be used to estimate the influence of a weak surface roughness on the light-scattering behavior of the underlying smooth scatterer. The effects obtained correspond with the results of other approaches and with the theoretical expectations of a weak surface roughness. In contrast to what is known for regular particles, there can be observed an essential difference between the phase functions of the underlying spherical scatterer and the corresponding higher-order Chebyshev particle if a higher absorptivity of the scattering medium is considered. This paper demonstrates additionally that Chebyshev polynomials can be simply combined with smooth geometries other than spheres.     

Directed evolution of an esterase from Pseudomonas fluorescens yields a mutant with excellent enantioselectivity and activity for the kinetic resolution of a chiral building block

A triple mutant of an esterase from Pseudomonas fluorescens (PFE) that was created by directed evolution exhibited high enantioselectivity (E=89) in a kinetic resolution and yielded the building block (S)-but-3-yn-2-ol. Surprisingly, a mutation close to the active site caused the formation of inclusion bodies, but remote mutations were found to be responsible for the high selectivity. Back mutations gave a variant (double mutant PFE Ile76Val/Val175Ala) that showed excellent selectivity (E=96) and activity (20 min for 50% conversion, which corresponds to 1.25 U per mg of protein).     

Product-oriented flavor research: learnings from the past, visions for the future

In the past flavor research and the development of new flavorings were constantly driven by the interaction of flavor analysis, structure elucidation, and chemical synthesis accompanied by sensory. Highly potent flavor compounds were identified in numerous food products and helped to establish a powerful toolbox for flavorists. Nowadays we experience the merging of various scientific disciplines, for example medicine, biology, chemistry, and various technologies in the field of flavor research, which shows direct impact on our understanding of flavors. At the same time modern life has profoundly changed our eating habits. This situation generates new challenges for product development teams, which represent all facets of technologies. This paper will illustrate different examples for the evolution of product-oriented flavor research and future trends.     

Comparative study on the dehydrogenation properties of TiCl4-doped LiAlH4 using different doping techniques

Lithium aluminum hydride (LiAlH₄) is an attractive hydrogen storage material because of its comparatively high gravimetric hydrogen storage capacity. In this study, titanium tetrachloride (TiCl₄), which is liquid at room temperature, was chosen as dopant because of its high catalytic efficiency regarding the dehydrogenation of LiAlH₄. Three low-energy doping methods (additive dispersion via ball milling at low rotation speed, magnetic stirring and magnetic stirring in ethyl ether) with different TiCl₄ concentrations were compared in order to obtain optimum dehydrogenation properties of LiAlH₄. At 80 °C, TiCl₄-doped LiAlH₄ can release up to 6.5 wt.%-H₂, which opens the way to use of exhaust heat of PEM fuel cells to trigger the hydrogen release from LiAlH₄.     

Refractive-index matching avoids local field corrections and scattering bias in solid-state Na2SO4 ultraviolet Raman cross-section measurements

We report a refractive-index matching method to measure nonabsorbing solid ultraviolet (UV) Raman cross-sections that avoids the local field correction and interface scattering of incident light. We used refractive-index-matched chloroform as an internal standard to determine the solid-state 995 cm(-1) Na(2)SO(4) 244 nm Raman cross-sections. The pure liquid chloroform 668 cm(-1) 244 nm Raman cross-section was determined by using acetonitrile as an internal standard and by calculating the local field corrections for the observed Raman intensities. Our measured 244 nm UV Raman cross-section of the solid-state 995 cm(-1) SO4(2-) band of 1.97 ± 0.07 × 10(-28) cm(2)/(molc·sr) is about half of its aqueous solution Raman cross-section, indicating interactions between the sulfate species in the solid that decrease the Raman polarizability.     

Effects of local fibre waviness on damage mechanisms and fatigue behaviour of biaxially loaded tube specimens

Damage development in and final failure process of glass fibre winding specimens during biaxial fatigue loading are investigated. The phenomena in nominally defect-free tubes and specimens exhibiting local fibre waviness in one layer are compared. A subset of wound tubes is analysed using non-destructive testing methods, i.e. air-coupled guided waves, thermography, optical fracture analysis by a high-speed camera, and discrete damage monitoring. Air-coupled guided waves are employed for detection of fibre waviness and for monitoring the failure progress initiated by this waviness. Stiffness degradation due to fatigue damage corresponds to a decline in guided wave velocity. Using infrared inspection, the fibre waviness can be detected in an early stage of fatigue life. Non-destructive evaluation reveals that initiation of final failure in the specimens is caused by local fibre waviness. Finally, the effect of local fibre waviness on the S–N curves of the specimens is illustrated.