Mechanical and Chemical Stability of Injection-Molded Microcantilevers Used for Sensing

Ultraviolet-ozone treatment is used as a standard surface cleaning procedure for removal of molecular organic contamination from analytical and sensing devices. Here, it is applied for injection-molded polymer microcantilevers before characterization and sensing experiments. This article examines the effects of the surface cleaning process using commercial equipment, in particular on the performance and mechanical properties of the cantilevers. It can be shown that the first chemical aging process essentially consist of the cross linking of the polymer chains together with a physical aging of the material. For longer exposure, the expected thermo-oxidative formation of carbonyl groups sets in and an exposure dependent chemical degradation can be detected. A process time of 20 min was found suitable as a trade-off between cleaning and stability

What is ‘wood’ – An anatomical re-definition

The technical definition of ‘wood’ is well accepted, but its botanical understanding remains vague. Different degrees and amounts of lignification in plants and their imprecise description, together with a conceptually doubtful life form catalog including trees, shrubs and herbs further complicate our understanding of ‘wood’. Here, we use permanent micro sections to demonstrate that the xylem and bark of terrestrial plants can vary from one tissue with a few lignified cells to an almost fully lignified tissue. This universal principle of plant growth and stabilization, accounting for all taxonomic units within vascular plants, suggests that the classical life form separation into herbs, shrubs and trees is not valid. An anatomical-based differentiation between ‘wood’, ‘woody’ and ‘woodiness’ is also only meaningful if supplemented by insight on the particular plant section and its lignified proportion. We therefore recommend utilizing the botanically more neutral term ‘stem anatomy’ instead of ‘wood anatomy’, which further implies integration of the xylem and bark of all terrestrial plants. Since dendrochronology considers shrubs, dwarf shrubs and perennial herbs in addition to trees, its semantic expansion toward ‘xylemchronology’ might be worthwhile considering.

The ovine cerebral venous system: comparative anatomy, visualization, and implications for translational research.

Cerebrovascular diseases are significant causes of death and disability in humans. Improvements in diagnostic and therapeutic approaches strongly rely on adequate gyrencephalic, large animal models being demanded for translational research. Ovine stroke models may represent a promising approach but are currently limited by insufficient knowledge regarding the venous system of the cerebral angioarchitecture. The present study was intended to provide a comprehensive anatomical analysis of the intracranial venous system in sheep as a reliable basis for the interpretation of experimental results in such ovine models. We used corrosion casts as well as contrast-enhanced magnetic resonance venography to scrutinize blood drainage from the brain. This combined approach yielded detailed and, to some extent, novel findings. In particular, we provide evidence for chordae Willisii and lateral venous lacunae, and report on connections between the dorsal and ventral sinuses in this species. For the first time, we also describe venous confluences in the deep cerebral venous system and an 'anterior condylar confluent' as seen in humans. This report provides a detailed reference for the interpretation of venous diagnostic imaging findings in sheep, including an assessment of structure detectability by in vivo (imaging) versus ex vivo (corrosion cast) visualization methods. Moreover, it features a comprehensive interspecies-comparison of the venous cerebral angioarchitecture in man, rodents, canines and sheep as a relevant large animal model species, and describes possible implications for translational cerebrovascular research.

One Health approach to use of veterinary pharmaceuticals

An estimated 6051 tons of active substances went into the production of veterinary pharmaceuticals (VPs) for the treatment of food animals in the European Union (EU) in 2004, including 5393 tons of antibiotics and 194 tons of antiparasitics (1). With global meat production projected to increase (2) and the growing market for companion animal pharmaceuticals (3), the use of VPs will continue to increase. Although VPs may benefit the health and welfare of domestic animals and the efficiency of food animal production, they can contaminate the environment through manufacturing, treatment of animals, and disposal of carcasses, offal, urine, feces, and unused products (4) (see the chart). This contamination is a threat to nontarget species, including humans. With Spain having recently authorized marketing of a VP that was banned in South Asia in the past decade in light of environmental impacts, we recommend strengthening of current procedures and addition of a more proactive, holistic, One Health approach applicable to all VPs.

Cell cycle-dependent phosphorylation of Theileria annulata schizont surface proteins.

The invasion of Theileria sporozoites into bovine leukocytes is rapidly followed by the destruction of the surrounding host cell membrane, allowing the parasite to establish its niche within the host cell cytoplasm. Theileria infection induces host cell transformation, characterised by increased host cell proliferation and invasiveness, and the activation of anti-apoptotic genes. This process is strictly dependent on the presence of a viable parasite. Several host cell kinases, including PI3-K, JNK, CK2 and Src-family kinases, are constitutively activated in Theileria-infected cells and contribute to the transformed phenotype. Although a number of host cell molecules, including IkB kinase and polo-like kinase 1 (Plk1), are recruited to the schizont surface, very little is known about the schizont molecules involved in host-parasite interactions. In this study we used immunofluorescence to detect phosphorylated threonine (p-Thr), serine (p-Ser) and threonine-proline (p-Thr-Pro) epitopes on the schizont during host cell cycle progression, revealing extensive schizont phosphorylation during host cell interphase. Furthermore, we established a quick protocol to isolate schizonts from infected macrophages following synchronisation in S-phase or mitosis, and used mass spectrometry to detect phosphorylated schizont proteins. In total, 65 phosphorylated Theileria proteins were detected, 15 of which are potentially secreted or expressed on the surface of the schizont and thus may be targets for host cell kinases. In particular, we describe the cell cycle-dependent phosphorylation of two T. annulata surface proteins, TaSP and p104, both of which are highly phosphorylated during host cell S-phase. TaSP and p104 are involved in mediating interactions between the parasite and the host cell cytoskeleton, which is crucial for the persistence of the parasite within the dividing host cell and the maintenance of the transformed state.

Immunohistochemical localization of osteoclastogenic cell mediators in feline tooth resorption and healthy teeth

Tooth resorption is among the most common and most challenging problems in feline dentistry It is a progressive disease eventually leading to tooth loss and often root replacement. The etiology of moth resorption remains obscure and to date no effective therapeutic approach is known. The present study is aimed at assessing the reliability of radiographic imaging and addressing the possible involvement of receptor activator of NF kappa B (RANK), its ligand (RANKL), and osteoprotegerin (OPG) in the process of tooth resorption. Teeth from 8 cats were investigated by means of radiographs and paraffin sections followed by immunolabeling. Six cats were diagnosed with tooth resorption based on histopathologic and radiographic findings. Samples were classified according to a four-stage diagnostic system. Radiologic assessment of tooth resorption correlated very strongly with histopathologic findings. Tooth resorption was accompanied by a strong staining with all three antibodies used, especially with anti-RANK and anti-RANKL antibodies. The presence of OPG and RANKL at the resorption site is indicative of repair attempts by fibroblasts and stromal cells. These findings should be extended by further investigations in order to elucidate the pathophysiologic processes underlying tooth resorption that might lead to prophylactic and/or therapeutic measures. J Vet Dent 27(2); 75 - 83, 2010

The venom composition of the parasitic wasp Chelonus inanitus resolved by combined expressed sequence tags analysis and proteomic approach

Background Parasitic wasps constitute one of the largest group of venomous animals. Although some physiological effects of their venoms are well documented, relatively little is known at the molecular level on the protein composition of these secretions. To identify the majority of the venom proteins of the endoparasitoid wasp Chelonus inanitus (Hymenoptera: Braconidae), we have randomly sequenced 2111 expressed sequence tags (ESTs) from a cDNA library of venom gland. In parallel, proteins from pure venom were separated by gel electrophoresis and individually submitted to a nano-LC-MS/MS analysis allowing comparison of peptides and ESTs sequences. Results About 60% of sequenced ESTs encoded proteins whose presence in venom was attested by mass spectrometry. Most of the remaining ESTs corresponded to gene products likely involved in the transcriptional and translational machinery of venom gland cells. In addition, a small number of transcripts were found to encode proteins that share sequence similarity with well-known venom constituents of social hymenopteran species, such as hyaluronidase-like proteins and an Allergen-5 protein. An overall number of 29 venom proteins could be identified through the combination of ESTs sequencing and proteomic analyses. The most highly redundant set of ESTs encoded a protein that shared sequence similarity with a venom protein of unknown function potentially specific of the Chelonus lineage. Venom components specific to C. inanitus included a C-type lectin domain containing protein, a chemosensory protein-like protein, a protein related to yellow-e3 and ten new proteins which shared no significant sequence similarity with known sequences. In addition, several venom proteins potentially able to interact with chitin were also identified including a chitinase, an imaginal disc growth factor-like protein and two putative mucin-like peritrophins. Conclusions The use of the combined approaches has allowed to discriminate between cellular and truly venom proteins. The venom of C. inanitus appears as a mixture of conserved venom components and of potentially lineage-specific proteins. These new molecular data enrich our knowledge on parasitoid venoms and more generally, might contribute to a better understanding of the evolution and functional diversity of venom proteins within Hymenoptera.

Spatio-Temporal Credit Assignment in Neuronal Population Learning

n learning from trial and error, animals need to relate behavioral decisions to environmental reinforcement even though it may be difficult to assign credit to a particular decision when outcomes are uncertain or subject to delays. When considering the biophysical basis of learning, the credit-assignment problem is compounded because the behavioral decisions themselves result from the spatio-temporal aggregation of many synaptic releases. We present a model of plasticity induction for reinforcement learning in a population of leaky integrate and fire neurons which is based on a cascade of synaptic memory traces. Each synaptic cascade correlates presynaptic input first with postsynaptic events, next with the behavioral decisions and finally with external reinforcement. For operant conditioning, learning succeeds even when reinforcement is delivered with a delay so large that temporal contiguity between decision and pertinent reward is lost due to intervening decisions which are themselves subject to delayed reinforcement. This shows that the model provides a viable mechanism for temporal credit assignment. Further, learning speeds up with increasing population size, so the plasticity cascade simultaneously addresses the spatial problem of assigning credit to synapses in different population neurons. Simulations on other tasks, such as sequential decision making, serve to contrast the performance of the proposed scheme to that of temporal difference-based learning. We argue that, due to their comparative robustness, synaptic plasticity cascades are attractive basic models of reinforcement learning in the brain.

Ultrasound-guided retrobulbar nerve block in horses: a cadaveric study

Objective  To develop an ultrasound-guided technique for retrobulbar nerve block in horses, and to compare the distribution of three different volumes of injected contrast medium (CM) (4, 8 and 12 mL), with the hypothesis that successful placement of the needle within the retractor bulbi muscle cone would lead to the most effective dispersal of CM towards the nerves leaving the orbital fissure. Study design  Prospective experimental cadaver study. Animals  Twenty equine cadavers. Methods  Ultrasound-guided retrobulbar injections were performed in 40 cadaver orbits. Ultrasound visualization of needle placement within the retractor bulbi muscle cone and spread of injected CM towards the orbital fissure were scored. Needle position and destination of CM were then assessed using computerized tomography (CT), and comparisons performed between ultrasonographic visualization of orbital structures and success rate of injections (intraconal needle placement, CM reaching the orbital fissure). Results  Higher scores for ultrasound visualization resulted in a higher success rate for intraconal CM injection, as documented on the CT images. Successful intraconal placement of the needle (22/34 orbits) resulted in CM always reaching the orbital fissure. CM also reached the orbital fissure in six orbits where needle placement was extraconal. With 4, 8 and 12 mL CM, the orbital fissure was reached in 16/34, 23/34 and 28/34 injections, respectively. Conclusion and clinical relevance  The present study demonstrates the use of ultrasound for visualization of anatomical structures and needle placement during retrobulbar injections in equine orbits. However, this approach needs to be repeated in controlled clinical trials to assess practicability and effectiveness in clinical practice.

Membrane disrupting antimicrobial peptide dendrimers with multiple amino termini

Antimicrobial peptide dendrimer H1 Leu8(Lys-Leu)4(Lys-Phe)2Lys-LysNH2 (Lys = branching lysine) was identified by screening a 6750-membered combinatorial library by the bead-diffusion assay. Sequence variations also revealed dendrimer bH1 Leu8(Dap-Leu)4(Dap-Phe)2Dap-LysNH2 (Dap = branching 2,3-diaminopropanoic acid) as a more potent analog. H1 and bH1 showed good antimicrobial activities mediated by membrane disruption (MIC = 2–4 μg mL−1 on Bacillus subtilis and Escherichia coli) but low hemolytic activity (MHC = 310 μg mL−1 respectively >2000 μg mL−1).

Perceptual Learning via Modification of Cortical Top-Down Signals

The primary visual cortex (V1) is pre-wired to facilitate the extraction of behaviorally important visual features. Collinear edge detectors in V1, for instance, mutually enhance each other to improve the perception of lines against a noisy background. The same pre-wiring that facilitates line extraction, however, is detrimental when subjects have to discriminate the brightness of different line segments. How is it possible to improve in one task by unsupervised practicing, without getting worse in the other task? The classical view of perceptual learning is that practicing modulates the feedforward input stream through synaptic modifications onto or within V1. However, any rewiring of V1 would deteriorate other perceptual abilities different from the trained one. We propose a general neuronal model showing that perceptual learning can modulate top-down input to V1 in a task-specific way while feedforward and lateral pathways remain intact. Consistent with biological data, the model explains how context-dependent brightness discrimination is improved by a top-down recruitment of recurrent inhibition and a top-down induced increase of the neuronal gain within V1. Both the top-down modulation of inhibition and of neuronal gain are suggested to be universal features of cortical microcircuits which enable perceptual learning.

Effects of a non-selective COX inhibitor and selective COX-2 inhibitors on contractility of human and porcine ureters in vitro and in vivo

BACKGROUND AND PURPOSE: Anti-inflammatory drugs are used in the treatment of acute renal colic. The aim of this study was to investigate the effects of selective COX-2 inhibitors and the non-selective COX inhibitor diclofenac on contractility of human and porcine ureters in vitro and in vivo, respectively. COX-1 and COX-2 receptors were identified in human ureter and kidney. EXPERIMENTAL APPROACH: Human ureter samples were used alongside an in vivo pig model with or without partial ureteral obstruction. COX-1 and COX-2 receptors were located in human ureters by immunohistochemistry. KEY RESULTS: Diclofenac and valdecoxib significantly decreased the amplitude of electrically-stimulated contractions in human ureters in vitro, the maximal effect (Vmax) being 120 and 14%, respectively. Valdecoxib was more potent in proximal specimens of human ureter (EC50=7.3 x 10(-11) M) than in distal specimens (EC50=7.4 x 10(-10) M), and the Vmax was more marked in distal specimens (22.5%) than in proximal specimens (8.0%) in vitro. In the in vivo pig model, parecoxib, when compared to the effect of its solvent, significantly decreased the maximal amplitude of contractions (Amax) in non-obstructed ureters but not in obstructed ureters. Diclofenac had no effect on spontaneous contractions of porcine ureter in vivo. COX-1 and COX-2 receptors were found to be expressed in proximal and distal human ureter and in tubulus epithelia of the kidney. CONCLUSIONS AND IMPLICATIONS: Selective COX-2 inhibitors decrease the contractility of non-obstructed, but not obstructed, ureters of the pig in vivo, but have a minimal effect on electrically-induced contractions of human ureters in vitro.