Tubular frameworks guiding orderly bone formation in the antler of the red deer (Cervus elaphus)

Deer antler is a bony tissue which re-grows every year after shedding. Growth speed and material properties of this tissue are truly remarkable, making it an interesting model for bone regeneration. Surprisingly, not much is known about the ultrastructure of the calcified tissues and the temporal sequence of their development during antler growth. We use a combination of imaging tools based on light and electron microscopy to characterize antler tissue at various stages of development. We observe that mineralized cartilage is first transformed into a bone framework with low degree of collagen fibril ordering at the micron level. This framework has a honeycomb-like appearance with the cylindrical pores oriented along the main antler axis. Later, this tissue is filled with primary osteons, whose collagen fibrils are mainly oriented along the pores, thus improving the antler's mechanical properties. This strongly suggests that to achieve very fast organ growth it is advantageous to have a longitudinal porous framework as an intermediate step in bone formation. The example of antler shows that geometric features of this framework are crucial, and a tubular geometry with a diameter in the order of hundred micrometers seems to be a good solution for fast framework-mediated bone formation.     

A reversible form of axon damage in experimental autoimmune encephalomyelitis and multiple sclerosis

In multiple sclerosis, a common inflammatory disease of the central nervous system, immune-mediated axon damage is responsible for permanent neurological deficits. How axon damage is initiated is not known. Here we use in vivo imaging to identify a previously undescribed variant of axon damage in a mouse model of multiple sclerosis. This process, termed 'focal axonal degeneration' (FAD), is characterized by sequential stages, beginning with focal swellings and progressing to axon fragmentation. Notably, most swollen axons persist unchanged for several days, and some recover spontaneously. Early stages of FAD can be observed in axons with intact myelin sheaths. Thus, contrary to the classical view, demyelination-a hallmark of multiple sclerosis-is not a prerequisite for axon damage. Instead, focal intra-axonal mitochondrial pathology is the earliest ultrastructural sign of damage, and it precedes changes in axon morphology. Molecular imaging and pharmacological experiments show that macrophage-derived reactive oxygen and nitrogen species (ROS and RNS) can trigger mitochondrial pathology and initiate FAD. Indeed, neutralization of ROS and RNS rescues axons that have already entered the degenerative process. Finally, axonal changes consistent with FAD can be detected in acute human multiple sclerosis lesions. In summary, our data suggest that inflammatory axon damage might be spontaneously reversible and thus a potential target for therapy.     

EGFR and EphA2 are host factors for hepatitis C virus entry and possible targets for antiviral therapy

Hepatitis C virus (HCV) is a major cause of liver disease, but therapeutic options are limited and there are no prevention strategies. Viral entry is the first step of infection and requires the cooperative interaction of several host cell factors. Using a functional RNAi kinase screen, we identified epidermal growth factor receptor and ephrin receptor A2 as host cofactors for HCV entry. Blocking receptor kinase activity by approved inhibitors broadly impaired infection by all major HCV genotypes and viral escape variants in cell culture and in a human liver chimeric mouse model in vivo. The identified receptor tyrosine kinases (RTKs) mediate HCV entry by regulating CD81-claudin-1 co-receptor associations and viral glycoprotein-dependent membrane fusion. These results identify RTKs as previously unknown HCV entry cofactors and show that tyrosine kinase inhibitors have substantial antiviral activity. Inhibition of RTK function may constitute a new approach for prevention and treatment of HCV infection.     

Characterization of short-term temperature, exposure, and solubilization effects on library compound quality

Many compound collections are stored under the same temperature conditions, which can limit flexibility by increasing the processing time required for high-demand compounds. In this study, the authors wanted to evaluate the impact of a hybrid-storage approach where high-demand compounds are stored for a shortened time period at room temperature to expedite processing operations. The use of a Covaris adaptive-focused acoustics platform was also characterized as a potential enhancement or alternative to storage at elevated temperatures. This study evaluated the impact of temperature, exposure, and solubilization on overall compound quality for short-term storage. A small library of 25 representative compounds was evaluated over an 18-week period to monitor the change in purity and concentration by high-performance liquid chromatography with ultraviolet detection. The authors concluded that temperature had a significant impact on compound concentration, and the effects due to exposure cycles were minimal. A storage time of 12 weeks at room temperature resulted in minimal compound loss, but storage times beyond this would be unacceptable because of a >20% decrease in concentration. Finally, the acoustic solubilization protocol also increased the number of compounds at the target concentration with no impact on overall purity, leading to a potential for increased storage times at frozen temperatures.     

Thromboelastometry (TEM) findings in disseminated intravascular coagulation in a pig model of endotoxinemia

Standard coagulation tests have a low specificity and sensitivity for diagnosing disseminated intravascular coagulation. The aim of this study was to determine whether whole blood thromboelastometry (TEM) detects lipopolysaccharide (LPS)-induced changes in coagulation. Blood samples from 10 pigs were drawn at baseline, before and at the end of LPS infusion and 2, 3, 4 and 5 h after the start of endotoxinemia. Simultaneous to TEM, standard coagulation tests and extended coagulation analysis including tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1) were performed. Endotoxinemia resulted in a significant acceleration of the nonactivated TEM (NATEM) clotting time 2 h after the end of LPS infusion; in contrast, the changes in international normalized ratio and activated partial thromboplastin time suggested delayed initiation of coagulation. NATEM maximum clot firmness (MCF) and fibrin-based thromboelastometry test (FIBTEM)-MCF decreased significantly from baseline until the last time point (from 64.6 ± 7.8 and 35.1 ± 12.8 mm to 52.8 ± 4.6 and 21.4 ± 11.8 mm, respectively; P = 0.01 for both parameters). A sharp, transient increase of t-PA had no effect on maximum lysis in the NATEM test. PAI-1 increased significantly 3 h after the start of LPS infusion, paralleled by a decrease in maximum lysis. In conclusion, TEM was superior to standard coagulation tests in reflecting initial activation of coagulation during endotoxinemia. TEM further suggested consumption of coagulation substrate; at the same time, inhibition of plasminogen activation was accompanied by improved clot stability. Further investigations are necessary to establish the clinical relevance of these findings.     

A plea for using qualitative aspects in the interpretation of ecological field data as revealed by the proof of carabid beetle assemblages of a pristine salt marsh

The evaluation of ecological field data can be done by an increasing number of quantitative methods. The application of these methods often is often blind against two kinds of problems: (i) the data often do not meet the requirements of a method, e.g., as an ultra-metric structure of the data in the case of hierarchical cluster analysis. In such cases, the result will be misleading because the presentation of results is ultra-metric independent on the structure of the data. (ii) Most of the animals are able to move actively or may drift passively by wind, etc. Therefore, species occurring by accident like vagrants have to be eliminated from the assemblage of animals at a particular site before a quantitative method is applied. In addition, the result of a quantitative analysis has to be checked for its ecological plausibility. This is a qualitative step, which can only be done by taking into account the known data on biology and ecology of the species.Some pitfalls of an exclusive application of quantitative methods will be demonstrated in this paper using a data set of salt marsh Carabidae.     

Myosin-Va transports the endoplasmic reticulum into the dendritic spines of Purkinje neurons

Extension of the endoplasmic reticulum (ER) into dendritic spines of Purkinje neurons is required for cerebellar synaptic plasticity and is disrupted in animals with null mutations in Myo5a, the gene encoding myosin-Va. We show here that myosin-Va acts as a point-to-point organelle transporter to pull ER as cargo into Purkinje neuron spines. Specifically, myosin-Va accumulates at the ER tip as the organelle moves into spines, and hydrolysis of ATP by myosin-Va is required for spine ER targeting. Moreover, myosin-Va is responsible for almost all of the spine ER insertion events. Finally, attenuation of the ability of myosin-Va to move along actin filaments reduces the maximum velocity of ER movement into spines, providing direct evidence that myosin-Va drives ER motility. Thus, we have established that an actin-based motor moves ER within animal cells, and have uncovered the mechanism for ER localization to Purkinje neuron spines, a prerequisite for synaptic plasticity.