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Christopher M Bloom,1 Ryan J Post,1 Joshua Mazick,1 Brittany Blumenthal,1 Caroline Doyle,1 Brenna Peters,1 Jeff Dyche,2 D Gene Davenport3 1Providence College, Providence, RI, USA; 2James Madison University, Harrisonburg, VA, USA; 3Saint Louis University, St Louis, MO, USA Abstract: Traditionally, the signaled avoidance (SA) paradigm has been used in an attempt to better understand human phobia. Animal models of this type have been criticized for ineffectively representing phobia. The SA model characterizes phobia as an avoidance behavior by presenting environmental cues, which act as warning signals to an aversive stimulus (ie, shock). Discriminated conditioned punishment (DCP) is an alternative paradigm that characterizes phobia as a choice behavior in which fear serves to punish an otherwise adaptive behavior. The present study quantifies the differences between the paradigms and suggests that DCP offers an alternative paradigm for phobia. Rats trained on either SA or DCP were compared on a number of behavioral variables relevant to human phobia. Results indicate that rats in the DCP paradigm responded significantly earlier to warning signals and were more effective at preventing shocks than rats in the SA paradigm. Implications of this alternative paradigm are discussed. Keywords: animal models, avoidance, fear conditioning, anxiety disorders

Generally injuries that remove or disrupt the endothelial cells lining blood vessels stimulate formation of vascular lesions composed of smooth muscle cells. One of the first events after such endothelial cell disruption is the generation of thrombin at the site of injury. This leads to platelet activation and thrombus formation. Evidence suggests that thrombus formation may stimulate smooth muscle-cell proliferation through the action of any number of factors emanating from the thrombus including platelet- or macrophage-derived factors, platelet-derived growth factor, basic fibroblast growth factor or thrombin. Atherosclerotic plaques continue to grow for many years. The slow indolent process of nondenuding chemical injury of the endothelium and lesion formation may be accelerated periodically by thrombi forming on the lumenal surface at sites of small denuding injuries leading to progressive atherosclerotic disease. Genistein, an isoflavonoid derived from soy products, has been shown to inhibit thrombin formation and platelet activation in vitro in addition to its antigrowth factor activity. Should it have similar actions in vivo, this compound has the potential to affect the progression of atherosclerotic disease by modifying coagulation responses. To assess the potential of genistein as a therapeutic for vascular disease, additional studies will be required to establish its effect on experimental vascular lesion formation. [ABSTRACT FROM AUTHOR]

El Niño events owe their name to their tendency to be locked to the seasonal cycle. A simple explanation is proposed here for the locking of the peak of ENSO's basin-scale warming to the end of the calendar year. The explanation is based on incorporating a seasonally varying coupled ocean--atmosphere instability strength into the delayed oscillator mechanism for the ENSO cycle. It is shown that the seasonally varying amplification of the Rossby and Kelvin ocean waves by the coupled instability forces the events to peak when this amplification is at its minimum strength, at the end of the calendar year. The mechanism is demonstrated using a simple delayed oscillator model and is further analyzed using the Cane--Zebiak model. Being based on the oversimplified delayed oscillator paradigm of ENSO, the proposed mechanism cannot be expected to fully explain the locking of observed events to the end of the year. However, the wave dynamics perspective it offers to approaching the ENSO phase-locking problem may serve as a first step toward a fuller explanation based on more realistic models and additional data analysis. [ABSTRACT FROM AUTHOR]

Abstract Periodic epidemics of malaria are a major public health problem for many sub-Saharan African countries. Populations in epidemic prone areas have a poorly developed immunity to malaria and the disease remains life threatening to all age groups. The impact of epidemics could be minimized by prediction and improved prevention through timely vector control and deployment of appropriate drugs. Malaria Early Warning Systems are advocated as a means of improving the opportunity for preparedness and timely response. Rainfall is one of the major factors triggering epidemics in warm semi-arid and desert-fringe areas. Explosive epidemics often occur in these regions after excessive rains and, where these follow periods of drought and poor food security, can be especially severe. Consequently, rainfall monitoring forms one of the essential elements for the development of integrated Malaria Early Warning Systems for sub-Saharan Africa, as outlined by the World Health Organization. The Roll Back Malaria Technical Resource Network on Prevention and Control of Epidemics recommended that a simple indicator of changes in epidemic risk in regions of marginal transmission, consisting primarily of rainfall anomaly maps, could provide immediate benefit to early warning efforts. In response to these recommendations, the Famine Early Warning Systems Network produced maps that combine information about dekadal rainfall anomalies, and epidemic malaria risk, available via their Africa Data Dissemination Service. These maps were later made available in a format that is directly compatible with HealthMapper, the mapping and surveillance software developed by the WHO's Communicable Disease Surveillance and Response Department. A new monitoring interface has recently been developed at the International Research Institute for Climate Prediction (IRI) that enables the user to gain a more contextual perspective of the current rainfall estimates by comparing them to previous seasons and climatological averages. These resources are available at no cost to the user and are updated on a routine basis.

The B cell antigen receptor (BCR) plays a crucial role in adaptive immunity, since antigen-induced signaling by the BCR leads to the activation of the B cell and production of antibodies during an immune response. However, the spatial nano-scale organization of the BCR on the cell surface prior to antigen encounter is still controversial. Here, we fixed murine B cells, stained the BCRs on the cell surface with immuno-gold and visualized the distribution of the gold particles by transmission electron microscopy. Approximately 30% of the gold particles were clustered. However the low staining efficiency of 15% precluded a quantitative conclusion concerning the oligomerization state of the BCRs. To overcome this limitation, we used Monte-Carlo simulations to include or to exclude possible distributions of the BCRs. Our combined experimental-modeling approach assuming the lowest number of different BCR sizes to explain the observed gold distribution suggests that 40% of the surface IgD-BCR was present in dimers and 60% formed large laminar clusters of about 18 receptors. In contrast, a transmembrane mutant of the mIgD molecule only formed IgD-BCR dimers. Our approach complements high resolution fluorescence imaging and clearly demonstrates the existence of pre-formed BCR clusters on resting B cells, questioning the classical cross-linking model of BCR activation.

Objective: Stromal cell-derived factor-1 (SDF-1) is a potent chemotaxin. Increased SDF-1 levels can be found in ischemic myocardium and might protect against ischemia-reperfusion injury. We hypothesized that transplantation of stem cells overexpressing SDF-1 might improve cardiac function after myocardial infarction (MI). We compared intramyocardial injection with a scaffold-based application of SDF-1-transfected cells., Methods: Skeletal myoblasts (SkMs) were isolated and expanded from newborn Lewis rats. Cells were transfected with pcDNA3-huSDF-1 and seeded on polyurethane (PU) scaffolds or diluted in medium for cell injection. Two weeks after myocardial infarction, seeded scaffolds were implanted epicardially into rats (group: PU-SDF-1-SkM) or the injection solution was applied intramyocardially (Inj-SDF-1-SkM). Additional groups were treated with non-transfected myoblasts either by injection (Inj-SkM) or by scaffold-based application (PU-SkM) or received a sham operation (Sham). Before this intervention and 6 weeks later, hemodynamic parameters were measured. Infarction size and neovascularization were assessed by histology at study end., Results: In sham animals, we detected a clear decrease in systolic function from intervention to study end. In group Inj-SkM and PU-SkM, all hemodynamic parameters that were assessed remained unchanged during observation time. Systolic function as measured by dP/dt(max) and SB-Emax was significantly improved in groups Inj-SDF-1-SkM and PU-SDF-1-SkM at study end without a difference between the two SDF-1 groups. Diastolic function measured by post-interventional dP/dt(min) was also increased in group Inj-SDF-1-SkM but not in PU-SDF-1-SkM. Histological analysis revealed a reduced infarction size in all treatment groups at study end but enhanced neovascularization was not observable., Conclusions: Transplantation of myoblasts overexpressing SDF-1 improves cardiac function after MI. The restoration of hemodynamic parameters is accompanied by a reduction in infarction size. This reverse remodeling capacity is independent of a scaffold-based application of the SDF-1-transfected cells., (Copyright © 2011 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.)

P2X₇R deficiency is associated with a less severe outcome in acute and chronic inflammatory disorders. Recently, we demonstrated that extracellular adenosine triphosphate is involved in the pathogenesis of asthma by modulating the function of dendritic cells (DCs). However, the role of the purinergic receptor subtype P2X₇ is unknown. To elucidate the role of P2X₇R in allergic airway inflammation (AAI) in vitro and in vivo, P2X₇R expression was measured in lung tissue and immune cells of mice or in humans with allergic asthma. By using a specific P2X₇R-antagonist and P2X₇R-deficient animals, the role of this receptor in acute and chronic experimental asthma was explored. P2X₇R was found to be up-regulated during acute and chronic asthmatic airway inflammation in mice and humans. In vivo experiments revealed the functional relevance of this finding because selective P2X₇R inhibition or P2X₇R deficiency was associated with reduced features of acute and chronic asthma in the ovalbumin-alum or HDM model of AAI. Experiments with bone marrow chimeras emphasized that P2X₇R expression on hematopoietic cells is responsible for the proasthmatic effects of P2X₇R signaling. In the DC-driven model of AAI, P2X₇R-deficient DCs showed a reduced capacity to induce Th2 immunity in vivo. Up-regulation of P2X₇R on BAL macrophages and blood eosinophils could be observed in patients with chronic asthma. Our data suggest that targeting P2X₇R on hematopoietic cells (e.g., DCs or eosinophils) might be a new therapeutic option for the treatment of asthma.

Beside its well described role in the central and peripheral nervous system 5-hydroxytryptamine (5-HT), commonly known as serotonin, is also a potent immuno-modulator. Serotoninergic receptors (5-HTR) are expressed by a broad range of inflammatory cell types, including dendritic cells (DCs). In this study, we aimed to further characterize the immuno-biological properties of serotoninergic receptors on human monocyte-derived DCs. 5-HT was able to induce oriented migration in immature but not in LPS-matured DCs via activation of 5-HTR(1) and 5-HTR(2) receptor subtypes. Accordingly, 5-HT also increased migration of pulmonary DCs to draining lymph nodes in vivo. By binding to 5-HTR(3), 5-HTR(4) and 5-HTR(7) receptors, 5-HT up-regulated production of the pro-inflammatory cytokine IL-6. Additionally, 5-HT influenced chemokine release by human monocyte-derived DCs: production of the potent Th1 chemoattractant IP-10/CXCL10 was inhibited in mature DCs, whereas CCL22/MDC secretion was up-regulated in both immature and mature DCs. Furthermore, DCs matured in the presence of 5-HT switched to a high IL-10 and low IL-12p70 secreting phenotype. Consistently, 5-HT favoured the outcome of a Th2 immune response both in vitro and in vivo. In summary, our study shows that 5-HT is a potent regulator of human dendritic cell function, and that targeting serotoninergic receptors might be a promising approach for the treatment of inflammatory disorders.

Cytotoxic necrotizing factor 1 (CNF1) is a protein toxin produced by pathogenic Escherichia coli strains. CNF1 constitutively activates small GTPases of the Rho family by deamidation of a glutamine, which is crucial for GTP hydrolysis. The toxin is taken up into mammalian cells by receptor-mediated endocytosis and is delivered from late endosomes into the cytosol. Here, we show that an approximately 55-kDa fragment of CNF1, which contains the catalytic domain and an additional part of the toxin, is present in the cytosol. The processing of this fragment requires an acidic pH and insertion of the toxin into the endosomal membrane. We define the cleavage site region as the region located between amino acids 532 and 544 of CNF1. The data provide insight into the complex mechanism of uptake of bacterial toxins into mammalian cells.

The cytotoxic necrotizing factors CNF1 and CNF2 produced by pathogenic Escherichia coli strains and CNF(Y) of Yersinia pseudotuberculosis constitutively activate small GTPases of the Rho family. They deamidate a glutamine (Gln63 in RhoA), which is crucial for GTP hydrolysis. CNF1 and CNF(Y) exhibit 61% identity on the amino acid level, with equal distribution over the whole molecule. Although the two toxins are homologous in the receptor binding domain, we show that they bind to different cellular receptors. CNF(Y) does not enter Caco-2 and CHO-K1 cells, which are responsive to CNF1. In contrast, HeLa, Hep-2, and HEK 293 cells do respond to both toxins. Competition studies with catalytically inactive mutants of the toxins revealed that binding of CNF1 has no influence on the uptake of CNF(Y) into HeLa cells. In contrast, uptake of CNF1 is retarded after preincubation of HeLa cells with the catalytically inactive mutant of CNF(Y), suggesting that the toxin receptors overlap. Moreover, we compared the pathways of the toxins from receptor binding into the cytosol and showed that both toxins are taken up independent of the presence of clathrin or lipid rafts and are released into the cytosol from acidified endosomes.

Periodic epidemics of malaria are a major public health problem for many sub-Saharan African countries. Populations in epidemic prone areas have a poorly developed immunity to malaria and the disease remains life threatening to all age groups. The impact of epidemics could be minimized by prediction and improved prevention through timely vector control and deployment of appropriate drugs. Malaria Early Warning Systems are advocated as a means of improving the opportunity for preparedness and timely response. Rainfall is one of the major factors triggering epidemics in warm semi-arid and desert-fringe areas. Explosive epidemics often occur in these regions after excessive rains and, where these follow periods of drought and poor food security, can be especially severe. Consequently, rainfall monitoring forms one of the essential elements for the development of integrated Malaria Early Warning Systems for sub-Saharan Africa, as outlined by the World Health Organization. The Roll Back Malaria Technical Resource Network on Prevention and Control of Epidemics recommended that a simple indicator of changes in epidemic risk in regions of marginal transmission, consisting primarily of rainfall anomaly maps, could provide immediate benefit to early warning efforts. In response to these recommendations, the Famine Early Warning Systems Network produced maps that combine information about dekadal rainfall anomalies, and epidemic malaria risk, available via their Africa Data Dissemination Service. These maps were later made available in a format that is directly compatible with HealthMapper, the mapping and surveillance software developed by the WHO's Communicable Disease Surveillance and Response Department. A new monitoring interface has recently been developed at the International Research Institute for Climate Prediction (IRI) that enables the user to gain a more contextual perspective of the current rainfall estimates by comparing them to previous seasons and climatological averages. These resources are available at no cost to the user and are updated on a routine basis.

The theory of the measurement of luminescent quantum yields using chemical actinometry is described. The sample's emission intensity is measured by nearly completely surrounding the sample with an actinometer solution, and the excitation intensity is directly measured with the same type of actinometer. The ratio of the measured sample emission intensity corrected for the fraction escaping through the excitation ports to the measured excitation intensity is the absolute luminescence yield. Equations, a suitable cell design, and computer calculated correction factors for different cell dimensions and optical densities are given. The absolute yield of the actinometer is not needed, only its relative response with wavelength. New quantum-flat actinometers which should greatly simplify the measurements are described.