Low-Cost Technologies Used in Corrosion Monitoring

Globally, corrosion is the costliest cause of the deterioration of metallic and concrete structures, leading to significant financial losses and unexpected loss of life. Therefore, corrosion monitoring is vital to the assessment of structures' residual performance and for the identification of pathologies in early stages for the predictive maintenance of facilities. However, the high price tag on available corrosion monitoring systems leads to their exclusive use for structural health monitoring applications, especially for atmospheric corrosion detection in civil structures. In this paper a systematic literature review is provided on the state-of-the-art electrochemical methods and physical methods used so far for corrosion monitoring compatible with low-cost sensors and data acquisition devices for metallic and concrete structures. In addition, special attention is paid to the use of these devices for corrosion monitoring and detection for in situ applications in different industries. This analysis demonstrates the possible applications of low-cost sensors in the corrosion monitoring sector. In addition, this study provides scholars with preferred techniques and the most common microcontrollers, such as Arduino, to overcome the corrosion monitoring difficulties in the construction industry.

RNA supply drives physiological granule assembly in neurons

Membraneless cytoplasmic condensates of mRNAs and proteins, known as RNA granules, play pivotal roles in the regulation of mRNA fate. Their maintenance fine-tunes time and location of protein expression, affecting many cellular processes, which require complex protein distribution. Here, we report that RNA granules-monitored by DEAD-Box helicase 6 (DDX6)-disassemble during neuronal maturation both in cell culture and in vivo. This process requires neuronal function, as synaptic inhibition results in reversible granule assembly. Importantly, granule assembly is dependent on the RNA-binding protein Staufen2, known for its role in RNA localization. Altering the levels of free cytoplasmic mRNA reveals that RNA availability facilitates DDX6 granule formation. Specifically depleting RNA from DDX6 granules confirms RNA as an important driver of granule formation. Moreover, RNA is required for DDX6 granule assembly upon synaptic inhibition. Together, this data demonstrates how RNA supply favors RNA granule assembly, which not only impacts subcellular RNA localization but also translation-dependent synaptic plasticity, learning, and memory.

Neuronal mitochondria transport Pink1 mRNA via synaptojanin 2 to support local mitophagy

PTEN-induced kinase 1 (PINK1) is a short-lived protein required for the removal of damaged mitochondria through Parkin translocation and mitophagy. Because the short half-life of PINK1 limits its ability to be trafficked into neurites, local translation is required for this mitophagy pathway to be active far from the soma. The Pink1 transcript is associated and cotransported with neuronal mitochondria. In concert with translation, the mitochondrial outer membrane proteins synaptojanin 2 binding protein (SYNJ2BP) and synaptojanin 2 (SYNJ2) are required for tethering Pink1 mRNA to mitochondria via an RNA-binding domain in SYNJ2. This neuron-specific adaptation for the local translation of PINK1 provides distal mitochondria with a continuous supply of PINK1 for the activation of mitophagy.

Large-Scale Monitoring of Resistance to Coumaphos, Amitraz, and Pyrethroids in Varroa destructor

Simple Summary

Varroa destructor, a parasitic mite of Apis mellifera, is causing severe damages to honey bee colonies worldwide. There are very few acaricides available to manage the parasite, and so the evolution of the mite’s resistance to acaricides poses a serious threat to controlling the mite. Using a combined approach that includes bioassays and genotyping, we estimated the expected efficacy of the treatments with acaricide products based on coumaphos, amitraz, and pyrethroids in apiaries from one of the most important beekeeping regions in Spain. This information was shared with the beekeeping community so that they can take informed and scientific-based decisions in the most convenient way to manage the parasite.

Abstract

Varroa destructor is an ectoparasitic mite causing devastating damages to honey bee colonies around the world. Its impact is considered a major factor contributing to the significant seasonal losses of colonies recorded every year. Beekeepers usually rely on a reduced set of acaricides to manage the parasite, usually the pyrethroids tau-fluvalinate or flumethrin, the organophosphate coumaphos, and the formamidine amitraz. However, the evolution of resistance in the mite populations is leading to an unsustainable scenario with almost no alternatives to reach an adequate control of the mite. Here, we present the results from the first large-scale and extensive monitoring of the susceptibility to acaricides in the Comunitat Valenciana, one of the most prominent apicultural regions in Spain. Our ultimate goal is to provide beekeepers with timely information to help them decide what would be the best alternative for a long-term control of the mites in their apiaries. Our data show that there is a significant variation in the expected efficacy of coumaphos and pyrethroids across the region, indicating the presence of a different ratio of resistant individuals to these acaricides in each population. On the other hand, the expected efficacy of amitraz was more consistent, though slightly below the expected efficacy according to the label.

Live cell imaging reveals 3'-UTR dependent mRNA sorting to synapses

mRNA transport restricts translation to specific subcellular locations, which is the basis for many cellular functions. However, the precise process of mRNA sorting to synapses in neurons remains elusive. Here we use Rgs4 mRNA to investigate 3′-UTR-dependent transport by MS2 live-cell imaging. The majority of observed RNA granules display 3′-UTR independent bidirectional transport in dendrites. Importantly, the Rgs4 3′-UTR causes an anterograde transport bias, which requires the Staufen2 protein. Moreover, the 3′-UTR mediates dynamic, sustained mRNA recruitment to synapses. Visualization at high temporal resolution enables us to show mRNA patrolling dendrites, allowing transient interaction with multiple synapses, in agreement with the sushi-belt model. Modulation of neuronal activity by either chemical silencing or local glutamate uncaging regulates both the 3′-UTR-dependent transport bias and synaptic recruitment. This dynamic and reversible mRNA recruitment to active synapses would allow translation and synaptic remodeling in a spatially and temporally adaptive manner.

Asymmetric subcellular mRNA distribution is important for local translation of neuronal mRNAs. Here the authors employed MS2 live-cell imaging and showed that the reporter mRNA containing the 3’ UTR of Rgs4 shows an anterograde transport bias, dependent on neuronal activity and the protein Staufen2, and mediates sustained mRNA recruitment to synapses.

Forebrain-specific, conditional silencing of Staufen2 alters synaptic plasticity, learning, and memory in rats

Background

Dendritic messenger RNA (mRNA) localization and subsequent local translation in dendrites critically contributes to synaptic plasticity and learning and memory. Little is known, however, about the contribution of RNA-binding proteins (RBPs) to these processes in vivo.

Results

To delineate the role of the double-stranded RBP Staufen2 (Stau2), we generate a transgenic rat model, in which Stau2 expression is conditionally silenced by Cre-inducible expression of a microRNA (miRNA) targeting Stau2 mRNA in adult forebrain neurons. Known physiological mRNA targets for Stau2, such as RhoA, Complexin 1, and Rgs4 mRNAs, are found to be dysregulated in brains of Stau2-deficient rats. In vivo electrophysiological recordings reveal synaptic strengthening upon stimulation, showing a shift in the frequency-response function of hippocampal synaptic plasticity to favor long-term potentiation and impair long-term depression in Stau2-deficient rats. These observations are accompanied by deficits in hippocampal spatial working memory, spatial novelty detection, and in tasks investigating associative learning and memory.

Conclusions

Together, these experiments reveal a critical contribution of Stau2 to various forms of synaptic plasticity including spatial working memory and cognitive management of new environmental information. These findings might contribute to the development of treatments for conditions associated with learning and memory deficits.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-017-1350-8) contains supplementary material, which is available to authorized users.

Preventing parastomal hernias with systematic intraperitoneal specifically designed mesh

BACKGROUND

Parastomal hernia is a very common complication after stoma formation. Current surgical techniques for repairing parastomal hernia have unsatisfactory results. We aim to assess our preliminary experience with prophylactic mesh placement at the time of stoma formation.

METHODS

Data were prospectively recorded. A specifically designed mesh made of polyvinyl fluoride with central conduit (Dynamesh IPST®) was fixed using an intra-peritoneal onlay technique. Safety was evaluated by means of surgical data and frequency of mesh-related complications, efficacy by the rate of parastomal hernias.

RESULTS

Thirty-four patients were included in the study. Three of them died before a year of follow up (not related to the stoma), so they were excluded. The other 31 patients (11 women and 20 men) were prospectively followed up after different pathologies resulting in a permanent colostomy. Twelve months after surgery CT-Scan imaging revealed two (6.4%) parastomal hernias, one of them already clinically suspected. During the follow up, 29% of the patients (n = 9) developed another type of hernia (incisional, inguinal or both). In five patients (16.1%) a light stomal retraction of the otherwise slightly prominent ostomy was observed. Median clinical follow-up was 17.5 months (range 12-34).

CONCLUSION

Prophylactic parastomal mesh placement might be a safe and effective procedure with a potential to reduce the risk of parastomal hernia. Routine use of this technique should be further analysed.

The ER Stress Sensor PERK Coordinates ER-Plasma Membrane Contact Site Formation through Interaction with Filamin-A and F-Actin Remodeling

Loss of ER Ca²⁺ homeostasis triggers endoplasmic reticulum (ER) stress and drives ER-PM contact sites formation in order to refill ER-luminal Ca²⁺. Recent studies suggest that the ER stress sensor and mediator of the unfolded protein response (UPR) PERK regulates intracellular Ca²⁺ fluxes, but the mechanisms remain elusive. Here, using proximity-dependent biotin identification (BioID), we identified the actin-binding protein Filamin A (FLNA) as a key PERK interactor. Cells lacking PERK accumulate F-actin at the cell edges and display reduced ER-PM contacts. Following ER-Ca²⁺ store depletion, the PERK-FLNA interaction drives the expansion of ER-PM juxtapositions by regulating F-actin-assisted relocation of the ER-associated tethering proteins Stromal Interaction Molecule 1 (STIM1) and Extended Synaptotagmin-1 (E-Syt1) to the PM. Cytosolic Ca²⁺ elevation elicits rapid and UPR-independent PERK dimerization, which enforces PERK-FLNA-mediated ER-PM juxtapositions. Collectively, our data unravel an unprecedented role of PERK in the regulation of ER-PM appositions through the modulation of the actin cytoskeleton.

The Oxygen Sensor PHD2 Controls Dendritic Spines and Synapses via Modification of Filamin A

Neuronal function is highly sensitive to changes in oxygen levels, but how hypoxia affects dendritic spine formation and synaptogenesis is unknown. Here we report that hypoxia, chemical inhibition of the oxygen-sensing prolyl hydroxylase domain proteins (PHDs), and silencing of Phd2 induce immature filopodium-like dendritic protrusions, promote spine regression, reduce synaptic density, and decrease the frequency of spontaneous action potentials independently of HIF signaling. We identified the actin cross-linker filamin A (FLNA) as a target of PHD2 mediating these effects. In normoxia, PHD2 hydroxylates the proline residues P2309 and P2316 in FLNA, leading to von Hippel-Lindau (VHL)-mediated ubiquitination and proteasomal degradation. In hypoxia, PHD2 inactivation rapidly upregulates FLNA protein levels because of blockage of its proteasomal degradation. FLNA upregulation induces more immature spines, whereas Flna silencing rescues the immature spine phenotype induced by PHD2 inhibition.

•

The oxygen sensor PHD2 is present in dendritic spines

•

PHD2 inhibition by hypoxia reduces spine maturation, synaptic density, and activity

•

Through hydroxylation, PHD2 targets filamin A for proteasomal degradation

•

Filamin A stabilization promotes dendritic spine remodeling

Deletion or Inhibition of the Oxygen Sensor PHD1 Protects against Ischemic Stroke via Reprogramming of Neuronal Metabolism

The oxygen-sensing prolyl hydroxylase domain proteins (PHDs) regulate cellular metabolism, but their role in neuronal metabolism during stroke is unknown. Here we report that PHD1 deficiency provides neuroprotection in a murine model of permanent brain ischemia. This was not due to an increased collateral vessel network. Instead, PHD1(-/-) neurons were protected against oxygen-nutrient deprivation by reprogramming glucose metabolism. Indeed, PHD1(-/-) neurons enhanced glucose flux through the oxidative pentose phosphate pathway by diverting glucose away from glycolysis. As a result, PHD1(-/-) neurons increased their redox buffering capacity to scavenge oxygen radicals in ischemia. Intracerebroventricular injection of PHD1-antisense oligonucleotides reduced the cerebral infarct size and neurological deficits following stroke. These data identify PHD1 as a regulator of neuronal metabolism and a potential therapeutic target in ischemic stroke.

The GRIP1/14-3-3 pathway coordinates cargo trafficking and dendrite development

Regulation of cargo transport via adaptor molecules is essential for neuronal development. However, the role of PDZ scaffolding proteins as adaptors in neuronal cargo trafficking is still poorly understood. Here, we show by genetic deletion in mice that the multi-PDZ domain scaffolding protein glutamate receptor interacting protein 1 (GRIP1) is required for dendrite development. We identify an interaction between GRIP1 and 14-3-3 proteins that is essential for the function of GRIP1 as an adaptor protein in dendritic cargo transport. Mechanistically, 14-3-3 binds to the kinesin-1 binding region in GRIP1 in a phospho-dependent manner and detaches GRIP1 from the kinesin-1 motor protein complex thereby regulating cargo transport. A single point mutation in the Thr956 of GRIP1 in transgenic mice impairs dendritic development. Together, our results show a regulatory role for GRIP1 during microtubule-based transport and suggest a crucial function for 14-3-3 proteins in controlling kinesin-1 motor attachment during neuronal development.

Inhibition of tumor angiogenesis and growth by a small-molecule multi-FGF receptor blocker with allosteric properties

Receptor tyrosine kinases (RTK) are targets for anticancer drug development. To date, only RTK inhibitors that block orthosteric binding of ligands and substrates have been developed. Here, we report the pharmacologic characterization of the chemical SSR128129E (SSR), which inhibits fibroblast growth factor receptor (FGFR) signaling by binding to the extracellular FGFR domain without affecting orthosteric FGF binding. SSR exhibits allosteric properties, including probe dependence, signaling bias, and ceiling effects. Inhibition by SSR is highly conserved throughout the animal kingdom. Oral delivery of SSR inhibits arthritis and tumors that are relatively refractory to anti-vascular endothelial growth factor receptor-2 antibodies. Thus, orally-active extracellularly acting small-molecule modulators of RTKs with allosteric properties can be developed and may offer opportunities to improve anticancer treatment.

Enhancement of endogenous neurogenesis in ephrin-B3 deficient mice after transient focal cerebral ischemia

Cerebral ischemia stimulates endogenous neurogenesis. However, the functional relevance of this phenomenon remains unclear because of poor survival and low neuronal differentiation rates of newborn cells. Therefore, further studies on mechanisms regulating neurogenesis under ischemic conditions are required, among which ephrin-ligands and ephrin-receptors (Eph) are an interesting target. Although Eph/ephrin proteins like ephrin-B3 are known to negatively regulate neurogenesis under physiological conditions, their role in cerebral ischemia is largely unknown. We therefore studied neurogenesis, brain injury and functional outcome in ephrin-B3^−/− (knockout) and ephrin-B3^+/+ (wild-type) mice submitted to cerebral ischemia. Induction of stroke resulted in enhanced cell proliferation and neuronal differentiation around the lesion site of ephrin-B3^−/− compared to ephrin-B3^+/+ mice. However, prominent post-ischemic neurogenesis in ephrin-B3^−/− mice was accompanied by significantly increased ischemic injury and motor coordination deficits that persisted up to 4 weeks. Ischemic injury in ephrin-B3^−/− mice was associated with a caspase-3-dependent activation of the signal transducer and activator of transcription 1 (STAT1). Whereas inhibition of caspase-3 had no effect on brain injury in ephrin-B3^+/+ animals, infarct size in ephrin-B3^−/− mice was strongly reduced, suggesting that aggravated brain injury in these animals might involve a caspase-3-dependent activation of STAT1. In conclusion, post-ischemic neurogenesis in ephrin-B3^−/− mice is strongly enhanced, but fails to contribute to functional recovery because of caspase-3-mediated aggravation of ischemic injury in these animals. Our results suggest that ephrin-B3 might be an interesting target for overcoming some of the limitations of further cell-based therapies in stroke.

VEGF mediates commissural axon chemoattraction through its receptor Flk1

Growing axons are guided to their targets by attractive and repulsive cues. In the developing spinal cord, Netrin-1 and Shh guide commissural axons toward the midline. However, the combined inhibition of their activity in commissural axon turning assays does not completely abrogate turning toward floor plate tissue, suggesting that additional guidance cues are present. Here we show that the prototypic angiogenic factor VEGF is secreted by the floor plate and is a chemoattractant for commissural axons in vitro and in vivo. Inactivation of Vegf in the floor plate or of its receptor Flk1 in commissural neurons causes axon guidance defects, whereas Flk1 blockade inhibits turning of axons to VEGF in vitro. Similar to Shh and Netrin-1, VEGF-mediated commissural axon guidance requires the activity of Src family kinases. Our results identify VEGF and Flk1 as a novel ligand/receptor pair controlling commissural axon guidance.

Permanent genetic resources added to Molecular Ecology Resources Database 1 February 2011-31 March 2011

This article documents the addition of 111 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Acipenser oxyrinchus desotoi, Anopheles nuneztovari sensu lato, Asellus aquaticus, Calopteryx splendens, Calopteryx virgo, Centaurea aspera, Centaurea seridis, Chilina dombeyana, Proctoeces cf. lintoni and Pyrenophora teres f. teres.

HRG inhibits tumor growth and metastasis by inducing macrophage polarization and vessel normalization through downregulation of PlGF

Polarization of tumor-associated macrophages (TAMs) to a proangiogenic/immune-suppressive (M2-like) phenotype and abnormal, hypoperfused vessels are hallmarks of malignancy, but their molecular basis and interrelationship remains enigmatic. We report that the host-produced histidine-rich glycoprotein (HRG) inhibits tumor growth and metastasis, while improving chemotherapy. By skewing TAM polarization away from the M2- to a tumor-inhibiting M1-like phenotype, HRG promotes antitumor immune responses and vessel normalization, effects known to decrease tumor growth and metastasis and to enhance chemotherapy. Skewing of TAM polarization by HRG relies substantially on downregulation of placental growth factor (PlGF). Besides unveiling an important role for TAM polarization in tumor vessel abnormalization, and its regulation by HRG/PlGF, these findings offer therapeutic opportunities for anticancer and antiangiogenic treatment.

Ultrasonic wave propagation in cementitious materials: a multiphase approach of a self-consistent multiple scattering model

This paper examines ultrasonic wave propagation through strongly heterogeneous materials such as cementitious materials, and deals meanly with the formulation of a multiphase approach of a self-consistent multiple scattering model, the so-called dynamic generalized self-consistent model (DGSCM) proposed by Yang [J. Appl. Mech. 70(2003) 575-582]. This extended model can describe the influence of the size and volume fraction of aggregates on cementitious materials, as well as the interaction, contribution, and influence of entrapped air voids together with the aggregates on frequency-dependent parameters such as the phase velocity and the attenuation coefficient. To show the performance of this approach, theoretical predictions were compared with experimental ultrasonic measurements over a wide frequency range from several mortar specimens with different features in their microstructure properties and concentrations of aggregates up to 60%. The multiphase approaches of both the DGSCM and the Waterman-Truell model (WT) were also compared. The obtained results of the multiphase DGSCM were found to be significantly better than those obtained from the N-phase WT model for ultrasonic measurements from cementitious materials at high aggregate concentrations. The feasibility of material characterization using the multiphase approach of DGSCM was also discussed.

On the measurement of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials

This paper deals with the measurement of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials, such as cementitious materials. To improve the measurement of this parameter on this kind of materials, a linear swept-frequency signal is used to drive an emitter transducer to conduct a through-transmission inspection in immersion. To filter out undesirable frequency content, time-frequency filtering and detection process are performed. The use of this method has been compared with two excitation techniques, the broadband and the narrowband pulses. The results obtained using the swept-frequency excitation together with the time-frequency filtering, allows the determination of the attenuation curves with high accuracy over a wide frequency range without the need for complicated equipment, and improves the effective bandwidth by using a unique pair of transducers.

Role of delta-like-4/Notch in the formation and wiring of the lymphatic network in zebrafish

OBJECTIVE

To study whether Notch signaling, which regulates cell fate decisions and vessel morphogenesis, controls lymphatic development.

METHODS AND RESULTS

In zebrafish embryos, sprouts from the axial vein have lymphangiogenic potential because they give rise to the first lymphatics. Knockdown of delta-like-4 (Dll4) or its receptors Notch-1b or Notch-6 in zebrafish impaired lymphangiogenesis. Dll4/Notch silencing reduced the number of sprouts producing the string of parchordal lymphangioblasts; instead, sprouts connecting to the intersomitic vessels were formed. At a later phase, Notch silencing impaired navigation of lymphatic intersomitic vessels along their arterial templates.

CONCLUSIONS

These studies imply critical roles for Notch signaling in the formation and wiring of the lymphatic network.

The neurovascular link in health and disease: an update

Although the nervous and vascular systems are functionally different, they show a high degree of anatomic parallelism and cross-talk. They also share similar mechanisms and molecular cues that regulate their development and maintenance. Malfunctioning of this cross-talk can cause or influence several vascular and neuronal disorders. In this review, we first provide a brief overview of the molecular and cellular mechanisms that govern the neurovascular link. Second, we focus on two neurodegenerative diseases, Alzheimer's disease and amyotrophic lateral sclerosis, to illustrate how a defective neurovascular link might contribute to their pathogenesis. Finally, we briefly discuss some therapeutic implications of the neurovascular link for designing strategies to treat these diseases.

Mechanisms of Vessel Branching

Filopodia, “the fingers that do the walking,” have been identified on endothelial cells at the tip of sprouting vessels for half a century, but the key role of the tip cell in vessel branching has been recognized only in the past few years. A model is emerging, whereby tip cells lead the way in a branching vessel, stalk cells elongate the sprout, and a very recently discovered phalanx cell ensures quiescence and perfusion of the newly formed branch. Recent genetic studies have shed light on the molecular signature of these distinct endothelial phenotypes; this provides a novel conceptual framework of how vessel morphogenesis occurs. Here, we will discuss the molecular candidates that participate in the decision of endothelial cells to adapt these distinct fates and highlight the emerging insights on how these cells send out filopodia while navigating.

Sand/cement ratio evaluation on mortar using neural networks and ultrasonic transmission inspection

The quality and degradation state of building materials can be determined by nondestructive testing (NDT). These materials are composed of a cementitious matrix and particles or fragments of aggregates. Sand/cement ratio (s/c) provides the final material quality; however, the sand content can mask the matrix properties in a nondestructive measurement. Therefore, s/c ratio estimation is needed in nondestructive characterization of cementitious materials. In this study, a methodology to classify the sand content in mortar is presented. The methodology is based on ultrasonic transmission inspection, data reduction, and features extraction by principal components analysis (PCA), and neural network classification. This evaluation is carried out with several mortar samples, which were made while taking into account different cement types and s/c ratios. The estimated s/c ratio is determined by ultrasonic spectral attenuation with three different broadband transducers (0.5, 1, and 2 MHz). Statistical PCA to reduce the dimension of the captured traces has been applied. Feed-forward neural networks (NNs) are trained using principal components (PCs) and their outputs are used to display the estimated s/c ratios in false color images, showing the s/c ratio distribution of the mortar samples.

Expression and purification of functional recombinant human pigment epithelium-derived factor (PEDF) secreted by the yeast Pichia pastoris

Pigment epithelium-derived factor (PEDF) combines neurotrophic, neuroprotective, anti-angiogenic, anti-tumor and neural stem cell self-renewal properties in a single molecule, making this protein a valuable potential therapeutic agent. We herein analyzed the expression of human recombinant full-length PEDF, and its N- and C-terminal regions (amino acids 1-243 and 195-418, respectively) in three mammalian cell lines (HEK-293T, COS-1, and 26HCMsv), and in the yeast Pichia pastoris. The highest production of recombinant PEDF was achieved in P. pastoris which secreted approximately 30 microg of full-length rPEDF, and 47 microg of C-terminal/ml of culture medium. Full-length rPEDF was purified by one-step Ni-chelating high-performance liquid chromatography, recovering almost 70% of secreted rPEDF with a purity of 98.6%. The C-terminal region of PEDF was isolated by low-pressure liquid chromatography, recovering around 4% of the recombinant molecule with a purity of 98%. The N-terminal region of PEDF was not secreted by any expression system assayed. The two isolated recombinant PEDF polypeptides inhibited in vitro endothelial cell migration, and full-length rPEDF also increased cerebellar granule cell survival, thus demonstrating their biological activity. These polypeptides can be used to investigate the therapeutic role of PEDF in cancer, neurodegenerative and ocular diseases, and stem cell-based therapies.

Grb4 and GIT1 transduce ephrinB reverse signals modulating spine morphogenesis and synapse formation

Dendritic spines are small protrusions emerging from dendrites that receive excitatory input. The process of spine morphogenesis occurs both in the developing brain and during synaptic plasticity. Molecules regulating the cytoskeleton are involved in spine formation and maintenance. Here we show that reverse signaling by the transmembrane ligands for Eph receptors, ephrinBs, is required for correct spine morphogenesis. The molecular mechanism underlying this function of ephrinBs involves the SH2 and SH3 domain-containing adaptor protein Grb4 and the G protein-coupled receptor kinase-interacting protein (GIT) 1. Grb4 binds by its SH2 domain to Tyr392 in the synaptic localization domain of GIT1. Phosphorylation of Tyr392 and the recruitment of GIT1 to synapses are regulated by ephrinB activation. Disruption of this pathway in cultured rat hippocampal neurons impairs spine morphogenesis and synapse formation. We thus show an important role for ephrinB reverse signaling in spine formation and have mapped the downstream pathway involved in this process.

Transgenic Mouse Proteomics Identifies New 14-3-3-associated Proteins Involved in Cytoskeletal Rearrangements and Cell Signaling

Identification of protein-protein interactions is crucial for unraveling cellular processes and biochemical mechanisms of signal transduction. Here we describe, for the first time, the application of the tandem affinity purification (TAP) and LC-MS method to the characterization of protein complexes from transgenic mice. The TAP strategy developed in transgenic mice allows the emplacement of complexes in their physiological environment in contact with proteins that might only be specifically expressed in certain tissues while simultaneously ensuring the right stoichiometry of the TAP protein versus their binding partners and represents a novelty in proteomics approaches used so far. Mouse lines expressing TAP-tagged 14-3-3zeta protein were generated, and protein interactions were determined. 14-3-3 proteins are general regulators of cell signaling and represent up to 1% of the total brain protein. This study allowed the identification of almost 40 novel 14-3-3zeta-binding proteins. Biochemical and functional characterization of some of these interactions revealed new mechanisms of action of 14-3-3zeta in several signaling pathways, such as glutamate receptor signaling via binding to homer homolog 3 (Homer 3) and in cytoskeletal rearrangements and spine morphogenesis by binding and regulating the activity of the signaling complex formed by G protein-coupled receptor kinase-interactor 1 (GIT1) and p21-activated kinase-interacting exchange factor beta (betaPIX).

Gold glyconanoparticles as new tools in antiadhesive therapy

Gold glyconanoparticles (GNPs) have been prepared as new multivalent tools that mimic glycosphingolipids on the cell surface. GNPs are highly soluble under physiological conditions, stable against enzymatic degradation and nontoxic. Thereby GNPs open up a novel promising multivalent platform for biological applications. It has recently been demonstrated that specific tumor-associated carbohydrate antigens (glycosphingolipids and glycoproteins) are involved in the initial step of tumor spreading. A mouse melanoma model was selected to test glyconanoparticles as possible inhibitors of experimental lung metastasis. A carbohydrate-carbohydrate interaction is proposed as the first recognition step for this process. Glyconanoparticles presenting lactose (lacto-GNPs) have been used successfully to significantly reduce the progression of experimental metastasis. This result shows for the first time a clear biological effect of lacto-GNPs, demonstrating the potential application of this glyconanotechnology in biological processes.

Chemical transformations on botryane skeleton. Effect on the cytotoxic activity

Eighteen compounds with a botryane skeleton have been obtained through chemical transformations of various toxins from the fungus Botrytis cinerea. During the course of these transformations, the C-10 carbon of the botryane skeleton was found to exhibit an interesting high regioselectivity to oxidizing and reducing agents. In addition, the cytotoxicity of 27 botryane derivatives was determined in vitro against Hs578T, MDA-MB-231, HT-1080, U87-MG, IMR-90, and HUVEC cell lines. The results of this study confirm that the cytotoxicity of botrydial (1) and its derivatives is related to the presence of a 1,5-dialdehyde functionality.

Inhibition of programmed cell death impairs in vitro vascular-like structure formation and reduces in vivo angiogenesis

Tissue remodeling during embryonic development and in the adult organism relies on a subtle balance between cell growth and apoptosis. As angiogenesis involves restructuring of preexisting endothelium, we examined the role of apoptosis in new vessel formation. We show that apoptosis occurs before capillary formation but not after vessels have assembled. Using the human umbilical vein endothelial cell (HUVEC) in vitro Matrigel angiogenesis model, we show that vascular-like structure formation requires apoptotic cell death through activation of a caspase-dependent mechanism and mitochondrial cytochrome c release. Vascular-like structure formation was further blocked by caspase inhibitors such as z-VAD or Ac-DEVD-CHO, using HUVEC and human lung microvascular endothelial cells. Overexpression of anti-apoptotic human Bcl-2 or baculovirus p35 genes in HUVEC altered endothelial cell rearrangement during in vitro angiogenesis, causing impaired vessel-like structure formation. Caspase inhibitors blocked VEGF- or bFGF-induced HUVEC angiogenesis on 2- or 3-D collagen gels, respectively, confirming that apoptosis was not the result of nonspecific cell death after seeding on the matrix. In an in vivo angiogenesis assay, caspase inhibitors blocked VEGF-dependent vascular formation at the alignment step, as demonstrated histologically. This evidence indicates that endothelial cell apoptosis may be relevant for precise vascular tissue rearrangement in in vitro and in vivo angiogenesis.

Decreased B16F10 melanoma growth and impaired vascularization in telomerase-deficient mice with critically short telomeres

Endothelial cell function and angiogenesis are modulated by aging. However, the underlying molecular mechanisms are largely unknown. Here we show that in telomerase-deficient mice Terc(-/-), short telomeres result in a sharp decrease in angiogenesis in both Matrigel implants and murine melanoma grafts. In the latter model, decreased microvessel counts in late generation Terc(-/-) mice led to diminished tumor cell proliferation and increased tumor cell apoptosis, resulting in a lower tumor growth rate. Our results indicate that telomere length is a key molecular determinant of angiogenic potential in vivo and that telomere length modifiers and telomerase inhibitors could be useful antiangiogenic agents.

Intraspecific heterogeneity in the mini-exon gene localization of Leishmania (Viannia) panamensis and Leishmania (Viannia) guyanensis from Colombia

Intraspecific heterogeneity was demonstrated in the mini-exon gene localization from Leishmania (Viannia) panamensis and L. (Viannia) guyanensis. Different karyotypes were detected in human isolates circulating in endemic areas of Colombia. The presence of mini-exon gene sequences on chromosomes of different sizes, ranging from 370 to 800 kb in L. (V.) panamensis and from 500 to 800 kb in L. (V.) guyanensis, was observed and was neither strain nor species specific. In some cases, hybridization with 2 chromosomes in the same strain was observed. The variability of chromosomal localization of mini-exon gene sequences of these 2 species highlights the genetic variability of the Viannia subgenus and the potential utility of the mini-exon gene as a molecular epidemiologic marker.

Thoracoabdominal aortic aneurysm repair in cardiac transplant recipients

We present here two cases of asymptomatic thoracoabdominal aortic aneurysms that were successfully operated on in heart transplant patients 8 and 23 months after transplantation. Thoracoabdominal aortic aneurysm was present prior to transplantation in one patient. In the other patient only the abdominal aortic aneurysm was found before transplantation. Indications for transplantation were ischemic and valvular cardiomyopathy. Surgical aortic aneurysm repair was performed with the standard technique. Both patients were discharged from the hospital. The possible contributing factors to the development and enlargement of aortic aneurysms and perioperative assessment are also discussed. Radiologic surveillance is warranted in any heart transplant recipient with abdominal or thoracoabdominal aortic aneurysms because of the more rapid aneurysm expansion.

Aortic valve replacement with bioprostheses in liver transplant recipients

Three cases of aortic valve replacement with porcine bioprostheses are reported in liver transplant recipients at two to six years after transplantation. Indications for aortic valve replacement (AVR) were aortic stenosis (n = 2) and aortic regurgitation (n = 1). The use of bioprostheses was recommended because of patient age, the need for multiple liver biopsies, and contraindication to the use of anticoagulation therapy. The patient who underwent AVR because of aortic regurgitation developed structural valve deterioration (SVD) during the next five years after surgery, and thus replacement of the bioprosthetic valve was required. Recipients of liver transplant who undergo valve replacement with tissue valves should be carefully followed up because of the risk of early SVD. AVR may be performed safely after liver transplantation.

Meglumine antimoniate, amiodarone and torsades de pointes: a case report

Pentavalent antimonial drugs used for the treatment of leishmaniasis have been associated with sudden deaths, probably due to the development of ventricular tachyarrhythmias. Prolongation of the QT interval and ventricular tachyarrhymias have been described in patients on amiodarone therapy. We report a case of recurrent torsades de pointes following treatment with pentavalent antimonial drugs and amiodarone.

Minicircle variable region probes for characterization of Leishmania (Viannia) species

The minicircle molecules present in the kinetoplast DNA (kDNA) network constitute a particularly useful molecular tool because they are a multicopy target and present a variable region that differs among minicircle classes in the same network. Using the polymerase chain reaction (PCR) and a set of primers directed outwardly from the minicircle conserved region, it is possible to prepare molecular probes representing the pool of variable regions from the different minicircle classes in the kDNA. In order to examine the specificity of the minicircle variable region as hybridization probes in Leishmania (Viannia) species, such fragments were amplified from reference strains and from a panel of isolates representing the zymodeme diversity of Leishmania (Viannia) in Colombia. The size of the amplified products was conserved in Leishmania (Viannia) braziliensis, Leishmania (Viannia) guyanensis, and Leishmania (Viannia) panamensis (650 bp) and diverged in Leishmania (Viannia) equatorensis and Leishmania (Viannia) colombiensis (850 bp). The amplified products were further hybridized to variable region pools of Leishmania braziliensis, Leishmania panamensis, Leishmania guyanensis, and Leishmania equatorensis reference strains. The results obtained from the hybridization experiments support this approach as a means of defining relationships among strains. Hybridization allowed homologies to be perceived, whereas restriction fragment length analysis of the amplified products yielded strain-specific profiles. Apparently, L. (V.) equatorensis and L. (V.) colombiensis minicircle variable regions have no or only low homology with those of other Leishmania (Viannia) species, showing the divergence of those species within the subgenus.

Human immunodeficiency virus type 2 produces a defect in CD3-gamma gene transcripts similar to that observed for human immunodeficiency virus type 1

T cells are central players in the immune response to infectious disease, with the specificity of their responses controlled by the T-cell receptor (TCR)/CD3 complex on the cell surface. Impairment of TCR/CD3-directed CD4(+) T-cell immune responses is frequently observed in individuals infected with human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2). Virus replication is also regulated by T-cell activation factors, with HIV-1 and HIV-2 responding to different TCR/CD3-directed cellular pathways. We previously demonstrated that HIV-1 infection of the human interleukin-2-dependent CD4(+) T-cell line WE17/10 abrogates TCR/CD3 function and surface expression by a specific loss of CD3-gamma gene transcripts. In this study, we show that HIV-2 provokes the same molecular defect in CD3-gamma gene transcripts, resulting in a similar but delayed progressive loss of TCR/CD3 surface expression after infection.

Association of Lutzomyia columbiana (Diptera: Psychodidae) with a leishmaniasis focus in Colombia due to species of the Leishmania mexicana complex

In Colombia, Leishmania mexicana has a scattered geographical distribution and no sand fly vectors have been associated with its transmission. During the present study, the anthropophilic sand fly Lutzomyia columbiana was found to be the only species collected using diverse methods, in a small focus of Le. mexicana in the municipality of Samaniego, SW Colombia. Ecological data indicate that this sand fly species is present in both peri and intradomestic habitats, where it readily bites man. Further evidence comes from experimental infections of wild-caught Lu. columbiana with Le. mexicana after feeding on infected hamsters. Based on these results, it is suggested that this sand fly is the most likely vector in the study area, suggesting the existence of a previously unknown sand fly-parasite association.

Eighteen-year follow up after Hancock II bioprosthesis insertion

BACKGROUND AND AIM OF THE STUDY

The long-term (18 years) results after aortic (AVR), mitral (MVR) and double (aortic/mitral, DVR) valve replacement with Hancock II bioprosthesis were investigated.

METHODS

Between 1978 and 1996, 279 Hancock II bioprostheses were implanted in 269 patients (166 males, 113 females; mean age 61.8+/-13.3 years). There were 135 AVR (48.4%), 122 MVR (43.8%) and 22 DVR (7.8%). Preoperatively, 208 patients (77.3%) were in NYHA functional class III/IV, 53 (19.7%) had previous cardiac surgery, and 19 (7.1%) underwent concomitant coronary artery bypass. Follow up (mean seven years) was 96% complete, with a total of 1,857 patient-years.

RESULTS

There were 20 early (7.3%), and 78 (29.0%) late deaths. At the last follow up, 68.3% of patients were in NYHA functional class I/II. The actuarial survival rate of patients at 10 and 18 years after discharge was 67.7+/-5.0% and 44.7+/-8.8% after AVR and 64.5+/-5.6% and 32.7+/-11.5% after MVR, respectively; survival after DVR was 74.0+/-11.2% at 12 years. At 10 and 18 years, actuarial freedom from thromboembolism was 83.5+/-4.5% and 73.1+/-10.5% after AVR and 82.1+/-4.3% and 73.2+/-7.3% after MVR; it was 78.4+/-15.0% after DVR at 12 years. At these times, actuarial freedom from hemorrhage was 88.7+/-3.8% and 83.5+/-6.2% after AVR and 79.0+/-4.9% and 32.6+/-23.3% after MVR; freedom after DVR was 36.2+/-26.6%. Probability of freedom from endocarditis at 10 and >15 years was 93.4+/-3.5% and 85.9+/-7.8% after AVR and 97.0+/-2.1% and 97.0+/-2.1% for MVR, respectively; freedom at 10 years after DVR was 75.0+/-21.6%. Freedom from structural deterioration at 10 and 18 years was 77.9+/-5.3% and 18.7+/-14.6% after AVR and 78.3+/-6.0% and 32.1+/-10.2% after MVR; freedom at 10 and 12 years after DVR was 64.0+/-17.5% and 32.0+/-24.2%. A low incidence of structural valve deterioration was found in AVR patients aged >65 years (p = 0.0478). Hemorrhage and paravalvular leak were more frequent in MVR (p = 0.0296 and 0.0309, respectively). No difference was seen in thromboembolism after anticoagulation for one or three months after AVR. Actuarial freedom from explantation at 10 and 18 years was 73.1+/-5.9% and 15.9+/-13.5% after AVR and 77.1+/-6.1% and 37.3+/-9.7% after MVR; freedom at 10 and 12 years after DVR was 72.0+/-17.8% and 24.0+/-20.4%.

CONCLUSION

Over an 18-year follow up, the Hancock II bioprosthesis has shown satisfactory results, with a low incidence of valve-related complications, especially in elderly patients in the aortic position.

Epidemiologic, genetic, and clinical associations among phenotypically distinct populations of Leishmania (Viannia) in Colombia

Phenotypic characterization of 511 strains of Leishmania, subgenus Viannia, isolated from Colombian patients was conducted based on electrophoretic polymorphisms of 13 isoenzymes. Ninety-one Colombian strains of L. braziliensis were the most heterogeneous, constituting seven zymodemes while 397 L. panamensis and 22 L. guyanensis strains yielded five and three zymodemes, respectively. Phosphogluconate dehydrogenase, nucleoside hydrolase, and superoxide dismutase were the most polymorphic enzymes in this collection of strains, and together with glucose-6-phosphate dehydrogenase, allowed the discrimination of the three aforementioned species. Hierarchical cluster analysis of the zymodemes using Jaccard's coefficient of similarities revealed two clusters, one constituted by L. braziliensis zymodemes, and another by three subgroups consisting of zymodemes of L. panamensis closely related to the species reference strain, another consisting of L. guyanensis zymodemes, and a third group distinguished by new electromorphs of proline iminopeptidase and aspartate aminotransferase that reacted with the L. panamensis-specific monoclonal antibody B-11. Multiple zymodemes of L. panamensis and L. guyanensis were found to be sympatrically transmitted in foci along the Pacific coast. Leishmania braziliensis variants were ubiquitous throughout the territory of Colombia; L. panamensis was prevalent in the western region and L. guyanensis was prevalent in the Orinoco and Amazon river basins in the eastern half of the country. Distinct zymodemes of L. panamensis predominated in the northern and southern regions of the Pacific coast. Nine zymodemes of all three species were isolated from mucosal lesions. Zymodeme 1.1 of L. braziliensis had the highest frequency of mucosal involvement (10% of the cases), and disease caused by this zymodeme had the longest mean time of evolution (31 months; P = 0.002). In addition to being useful in describing epidemiologic relationships, the intraspecific heterogeneity of strains of the Viannia subgenus within and among foci can be used to understand such fundamental questions as the pathogenicity of different populations of parasites, and the induction of cross-protection against related parasites.

Carbohydrate and LPG expression in Leishmania viannia subgenus

Glycosylated molecules expressed on the cell surface of Leishmania promastigotes contribute to the outcome of contact between the parasite and its invertebrate and vertebrate hosts. The expression of several such molecules is growth phase dependent. Information on the expression of carbohydrates by Leishmania of the Viannia subgenus (braziliensis complex), a widespread cause of morbidity in the Americas, is fragmentary. We have examined the relationship between growth phase and the expression of glycosylated surface structures in WHO reference strains of 3 species of the Viannia subgenus, i.e., L. panamensis, L. guyanensis, and L. braziliensis. Agglutination with lectins and the monoclonal antibody specific for the repeat unit of L. donovani lipophosphoglycan, CA7AE, distinguished logarithmic and stationary-phase promastigotes of all 3 species. Flow cytometry revealed increased heterogeneity and disparity in the expression of the repeat unit epitope in stationary-as compared to logarithmic-phase promastigotes. Biochemical analyses showed the LPG repeat unit of all 3 species reference strains to be constituted by mannose and galactose with little or no substitution and, hence, to be similar to the LPG of L. donovani. Initial quantitative analyses of L. braziliensis LPG indicated a 10-fold lower quantity of LPG in this species than L. donovani and an increase in the size of LPG in the stationary phase. These findings provide bases for isolating and biologically characterizing phenotypically distinct populations of promastigotes and for identifying molecular determinants of the host parasite-relationship among Leishmania Viannia.

Didelphis marsupialis, an important reservoir of Trypanosoma (Schizotrypanum) cruzi and Leishmania (Leishmania) chagasi in Colombia

The role of Didelphis marsupialis as a reservoir of zoonotic hemoflagellates was examined in two ecologically distinct settings in Colombia. While 72% (12 of 18) of the opossums collected in the tropical rain forest harbored Trypanosoma cruzi, other mammals in the area had lower infection rates: 1.3% (Proechymis semispinosus [spiny rat]; 13% Tylomys mirae [climbing rat]; and 6% Rattus rattus). Trypanosoma cruzi isolates from D. marsupialis were similar to zymodeme 1 (Z1), and two of four phenotypes were shared with Tylomys mirae, which is also predominantly arboreal. Terrestrial (P. semispinosus) and peridomestic (R. rattus) animals were infected with Z3 or other Z1 phenotypes, respectively. Schizodeme analysis showed polymorphisms among isolates from mammals, reflecting diverse modes of transmission, and a complex epidemiologic situation. Despite the lower infection rate of the opossum (14%) found in our study in the tropical dry forest as compared with the tropical wet forest, Chagas' disease has been reported only in the former area. This suggests that the lack of alternative blood sources for triatomines of the tropical dry forest, where mammals are less abundant than in the wet forest, may increase the risk of human infection. Among several species of mammals captured in the tropical dry forest, Leishmania chagasi was isolated from 22.7% (5 of 22) D. marsupialis. This finding confirms the important role of opossums in Colombian foci of visceral leishmaniasis, including those where the phlebotomine species involved in transmission is Lutzomyia evansi, an alternative vector to the more common Lutzomyia longipalpis.