Entry Path Research Articles

Functional interaction between AQP2 and TRPV4 in renal cells

We have previously demonstrated that renal cortical collecting duct cells (RCCD(1)), responded to hypotonic stress with a rapid activation of regulatory volume decrease (RVD) mechanisms. This process requires the presence of the water channel AQP2 and calcium influx, opening the question about the molecular identity of this calcium entry path. Since the calcium permeable nonselective cation channel TRPV4 plays a crucial role in the response to mechanical and osmotic perturbations in a wide range of cell types, the aim of this work was to test the hypothesis that the increase in intracellular calcium concentration and the subsequent rapid RVD, only observed in the presence of AQP2, could be due to a specific activation of TRPV4. We evaluated the expression and function of TRPV4 channels and their contribution to RVD in WT-RCCD(1) (not expressing aquaporins) and in AQP2-RCCD(1) (transfected with AQP2) cells. Our results demonstrated that both cell lines endogenously express functional TRPV4, however, a large activation of the channel by hypotonicity only occurs in cells that express AQP2. Blocking of TRPV4 by ruthenium red abolished calcium influx as well as RVD, identifying TRPV4 as a necessary component in volume regulation. Even more, this process is dependent on the translocation of TRPV4 to the plasma membrane. Our data provide evidence of a novel association between TRPV4 and AQP2 that is involved in the activation of TRPV4 by hypotonicity and regulation of cellular response to the osmotic stress, suggesting that both proteins are assembled in a signaling complex that responds to anisosmotic conditions.

Model of health? Distributed preparedness and multi-agency interventions surrounding UK regional airports

The liberalisation of the European aviation sector has multiplied paths of entry into the United Kingdom (UK) for the international traveller. These changing mobilities necessitate a reconceptualisation of the border as a series of potentially vulnerable nodes occurring within, and extending beyond, national boundaries. In this paper, we consider the border through the lens of port health, the collective term for various sanitary operations enacted at international transport terminals. In the UK, a critical player in the oversight of port health is the Health Protection Agency (HPA), which became a non-Departmental public body in 2005. A major part of port health is preparedness, a set of techniques aimed at managing, and responding to, emergencies of public health concern. More recently, certain jurisdictions have embarked on public health preparedness work across a number of different geographical scales. Using methods pioneered by the military, this form of ‘distributed preparedness’ is of increased interest to social science and medical scholars. With reference to case studies conducted in localities surrounding two UK regional airports following the 2009–10 H1N1 influenza pandemic, we consider the extent to which distributed preparedness as a concept and a set of practices can inform current debates - in the UK, and beyond - concerning interventions at the border ‘within’.

Steven Klepper: Recipient of the 2011 Global Award for Entrepreneurship Research

This article reviews the academic contributions of the 2011 receiver of the Global Award for Entrepreneurship Research, Professor Steven Klepper, Carnegie Mellon University. The Global Award consists of 100,000 Euro and a statuette of the internationally renowned Swedish sculpture Carl Milles. Klepper has made breakthrough analyses in the realm of industrial dynamics, emphasizing the regularities in the time paths of entry of new producers, exit of incumbent firms, spin-offs and innovation. His work is predominantly empirical but he has also played an essential role in developing more rigorous theoretical models of phenomena such as spin-offs. Of particular importance is how Klepper has managed to link traditional neoclassical models with evolutionary theory as well as entrepreneurship research with mainstream economics.

A Percutaneous Technique for Reduction and Internal Fixation of Displaced Intra-Articular Calcaneal Fractures.

A retrospective cohort study demonstrated that, in comparison with open reduction and internal fixation through an extensile lateral approach, our percutaneous technique for reduction and internal fixation of displaced intra-articular calcaneal fractures decreases the rate of complications and achieves and maintains extra-articular fracture reductions just as well. Position the patient correctly to obtain excellent fluoroscopic views, which are key to the procedure. The techniques for reducing and fixing joint depression and tongue-type calcaneal fractures differ and will be described separately. Identify screw entry points and paths using fluoroscopic images, and confirm the final positions with c-arm imaging. Apply a splint; then obtain postoperative images to confirm fracture reduction and screw placement. The results of percutaneous reduction of displaced intra-articular calcaneal fractures in seventy-nine patients with a total of eighty-three fractures were compared with those obtained by another surgeon using the extensile lateral approach. IndicationsContraindicationsPitfalls & Challenges.

Platform envelopment

AbstractDue to network effects and switching costs in platform markets, entrants generally must offer revolutionary functionality to win substantial market share. We explore a second entry path that does not rely upon Schumpeterian innovation: platform envelopment. Through envelopment, a provider in one platform market can enter another platform market, and combine its own functionality with that of the target in a multi‐platform bundle that leverages shared user relationships. Envelopers capture market share by foreclosing an incumbent's access to users; in doing so, they harness the network effects that previously had protected the incumbent. We present a typology of envelopment attacks based on whether platform pairs are complements, weak substitutes, or functionally unrelated and we analyze conditions under which these attack types are likely to succeed. Copyright © 2011 John Wiley & Sons, Ltd.

Physical and structural characteristics of acrylated poly(ethylene glycol)–alginate conjugates

Transmucosal delivery of therapeutic agents is a non-invasive approach that utilizes human entry paths such as the nasal, buccal, rectal and vaginal routes. Mucoadhesive polymers have the ability to adhere to the mucus layer covering those surfaces and by that promote drug release, targeting and absorption. We have recently demonstrated that acrylated polymers display enhanced mucoadhesive properties due to their ability to covalently attach to mucus type glycoproteins. We have synthesized an acrylated poly(ethylene glycol)–alginate conjugate (alginate–PEGAc), a molecule which combines the gelation ability of alginate with the mucoadhesion properties arising from both the characteristics of poly(ethylene glycol) and the acrylate functionality. In the current investigation we introduce an in-depth characterization of the thermal, mechanical and structural properties of alginate–PEGAc aimed at gaining a better knowledge of its structure–function relations. The thermal stability, evaluated by thermal gravimetric analysis and differential scanning calorimetry, was compared with that of alginate and the intermediate product thiolated alginate. Dehydration at temperatures up to 200 °C was detected for all samples, followed by distinctive decomposition steps arising from the decomposition of the polymer backbone and side-chains. The nanostructure of the solutions and gels was evaluated from small angle X-ray scattering patterns, to which the “broken rod linked by flexible chain” model was fitted, and from rheology measurements. The maxima arising from electrostatic repulsion between the highly charged alginate chains was diminished for both modified alginate samples, suggesting that modification led to electrostatic screening. Alginate, thiolated alginate and alginate–PEGAc cross-linked with calcium ions demonstrated similar scattering patterns. However, different scattering intensities, gel strengths, and gelation kinetics were observed, suggesting a decrease in the cross-linking density in the order alginate > thiolated alginate > alginate–PEGAc. These results were attributed to the increased size of the grafted side groups, which interfere with the gelation process. Examining the effect of the method of alginate–PEGAc gelation (physical or chemical) has shown that additional UV irradiation of calcium cross-linked gels did not cause a significant change in the network structure and strength. It seems that the concentration of the acrylated end group is not high enough to create a chemically cross-linked network.

Nail-gun injury of the cervical spine: simple technique for removal of a barbed nail

Although nail-gun injuries are a common form of penetrating low-velocity injury, impalement with barbed nails has been underreported to date. Barbed nails are designed to resist dislodgment once embedded, and any attempt at removal may splay open the barbs along the path of entry, with the potential for significant soft-tissue and neurovascular injury. A 25-year-old man sustained a nail impalement of the cervical spine from accidental discharge of a nail gun. The patient was noted to be fully conscious with no neurological deficits. Cervical Zone 2 impalement was noted, with only the head of the nail visible. Angiography revealed the nail lying just anterior to the right vertebral artery (VA), with compression of the vessel. Preoperatively, analysis of a similar nail revealed that orientation of the head determined position of the barbs. A deep neck dissection was then performed to the lateral aspect of the C-3 body, using the nail as a guide. Prior to removal, the nail was turned 180° to change the position of the barbs, to prevent injury to the VA. Nail removal was uneventful. The authors present a simple technique for treatment of a nail-gun injury with a barbed nail. Prior to removal, radiographic analysis of the impaled nail must be performed to determine the presence of barbs. If possible, the surgeon should request a similar nail for analysis prior to surgery. Last, the treating surgeon must have knowledge of the barbs' position at all times during nail removal, to prevent damage to critical structures.

The structure of CYP101D2 unveils a potential path for substrate entry into the active site

The cytochrome P450 CYP101D2 from Novosphingobium aromaticivorans DSM12444 is closely related to CYP101D1 from the same bacterium and to P450cam (CYP101A1) from Pseudomonas putida. All three are capable of oxidizing camphor stereoselectively to 5-exo-hydroxycamphor. The crystal structure of CYP101D2 revealed that the likely ferredoxin-binding site on the proximal face is largely positively charged, similar to that of CYP101D1. However, both the native and camphor-soaked forms of CYP101D2 had open conformations with an access channel. In the active site of the camphor-soaked form, the camphor carbonyl interacted with the haem-iron-bound water. Two other potential camphor-binding sites were also identified from electron densities in the camphor-soaked structure: one located in the access channel, flanked by the B/C and F/G loops and the I helix, and the other in a cavity on the surface of the enzyme near the F helix side of the F/G loop. The observed open structures may be conformers of the CYP101D2 enzyme that enable the substrate to enter the buried active site via a conformational selection mechanism. The second and third binding sites may be intermediate locations of substrate entry and translocation into the active site, and provide insight into a multi-step substrate-binding mechanism.

Western Pacific coastal sources of iron, manganese, and aluminum to the Equatorial Undercurrent

We present results from the first zonal transect of iron, aluminum, and manganese conducted from the western source region of the Equatorial Undercurrent (EUC) to the central equatorial Pacific. Trace metals were elevated along the slope of Papua New Guinea and within the New Guinea Coastal Undercurrent (NGCU), which is the primary Southern Hemisphere entry path of water to the EUC. Subsurface maxima in total acid‐soluble iron, aluminum, and manganese were evident in the EUC. These maxima were generally greatest in the western equatorial Pacific and decreased in magnitude eastward. Maxima in iron and aluminum persisted to 140°W; maxima in manganese extended to 175°W. Iron and manganese maxima were deeper (25–75 m) than aluminum maxima and located in the lower EUC, which undergoes less interior ocean mixing than shallower waters. The depth of the aluminum subsurface maxima correlated strongly (r = 0.88) with the depth of the EUC velocity maximum. Surface waters were enriched in aluminum and manganese offshore of Papua New Guinea. Surface metal concentrations decreased eastward throughout the western warm pool up to the longitude (∼180°W) of the salinity front. Detrital sediment input from either direct riverine input or sediment resuspension appeared to be the primary mechanism of supplying metals to the NGCU. We estimated eastward fluxes of metals in the EUC and found greatest fluxes in the western equatorial Pacific between 160°E and 165°E, except for aluminum. Fluxes of aluminum and, to a lesser extent, manganese increased concurrently with water volume transport in the central equatorial Pacific. Iron transport in the EUC remained constant east of the dateline, apparently due to the combined effects of dilution by meridional entrainment and scavenging. Iron was mobilized in a highly active western boundary current region and transported eastward in the lower EUC.

Avoiding varus malreduction during cephalomedullary nailing of intertrochanteric hip fractures

We describe a technique for preventing varus malreduction of intertrochanteric hip fractures during fixation with a cephalomedullary nail. When the entry reamer guidewire is positioned in the fracture line, passage of the entry reamer may simply push the proximal fragment medially and the distal fragment laterally rather than ream the accurate entry path. Subsequent nail insertion will result in a varus deformity of the proximal femur. The simple technique described in this report uses a brief period of over-distraction to wedge the entry reamer guidewire against the lateral edge of the proximal fragment, permitting the reamer to cut a correct path in the lateral edge of the proximal fragment. Creation of a proper entry path is essential to maintain anatomic reduction during cephalomedullary nailing of intertrochanteric hip fractures.

Modeling anthropogenic substances in coastal wetlands: Application to herbicides in the Camargue (France)

The purpose of this work was to develop a coupled hydrological and chemical model that can simulate time-dependent concentrations of pesticides and their degradation products in shallow coastal water bodies of variable volumes. The model was applied to simulate the exposure of two herbicides, oxadiazon and MCPA, in three interconnected lagoons which form the coastal wetlands of the Camargue. These shallow lagoons and adjacent marshes are of international importance for the preservation of biodiversity. The chemical fugacity and reactivity are modeled in these complex ecosystems as in classical fate models for well-mixed lakes, but additionally water exchanges between the lagoons, seawater intrusion, variable evaporation rates and fluctuating water volumes of the lagoons are incorporated. Analytical solutions for coupled differential equations for the water volumes of the lagoons, the salinities, and the concentrations of pesticides were derived and evaluated using the software Maple. The model was calibrated using salinity data and was able to simulate measured concentrations of oxadiazon and MCPA and two subsequent degradation products of MCPA in the main lagoon in Camargue. Interestingly, model simulations differed from real observations in the two smaller lower lagoons, and the model served tracking so far unknown entry paths of herbicides into these lagoons.

Free and ATP-bound structures of Ap4A hydrolase fromAquifex aeolicusV5

Asymmetric diadenosine tetraphosphate (Ap(4)A) hydrolases degrade the metabolite Ap(4)A back into ATP and AMP. The three-dimensional crystal structure of Ap(4)A hydrolase (16 kDa) from Aquifex aeolicus has been determined in free and ATP-bound forms at 1.8 and 1.95 A resolution, respectively. The overall three-dimensional crystal structure of the enzyme shows an alphabetaalpha-sandwich architecture with a characteristic loop adjacent to the catalytic site of the protein molecule. The ATP molecule is bound in the primary active site and the adenine moiety of the nucleotide binds in a ring-stacking arrangement equivalent to that observed in the X-ray structure of Ap(4)A hydrolase from Caenorhabditis elegans. Binding of ATP in the active site induces local conformational changes which may have important implications in the mechanism of substrate recognition in this class of enzymes. Furthermore, two invariant water molecules have been identified and their possible structural and/or functional roles are discussed. In addition, modelling of the substrate molecule at the primary active site of the enzyme suggests a possible path for entry and/or exit of the substrate and/or product molecule.

Trypanosoma evansi: Pharmacological evidence of a nicotinic acetylcholine receptor

The role of calcium and its relevance have been deeply revised with respect to trypanosomatids, as the mechanism by which calcium enters trypanosomes was, until now, not well understood. There is evidence supporting the presence of a nAChR in another member of the trypanosomatidae family, Trypanosoma cruzi, these receptors being one entry path to calcium ions. The aims of this work were to determine if there was a nicotinic acetylcholine receptor (nAChR) in Trypanosoma evansi, and to subsequently perform a partial pharmacological characterization of this receptor. After being loaded with FURA-2AM, individual cells of T. evansi, were exposed to cholinergic compounds, and the cells displayed a dose-dependent response to carbachol. This observation indicated that a cholinergic receptor may be present in T. evansi. Although a dose-dependent response to muscarine could not be demonstrated, nicotine could promote an incremental dose-dependent response. The relative potency of this specific agonist of nAChR is in agreement with previous reports. The estimated affinity values were a K d 1 value of 29.6 ± 5.72 nM and a K d 2 value of 315.9 ± 26.6 nM, which is similar to the K d value reported for the α4 nicotinic receptor. The Hill coefficients were determined to be an n 1 of 1.2 ± 0.3 and an n 2 of 4.2 ± 1.3. Finally, our calculations indicated that there are about 1020 receptors in each T. evansi parasite, which is approximately 15-fold lower than the number reported in Torpedo californica electric cells. These results suggest the presence of a nAChR in T. evansi, which is able to bind nicotinic ligands and induce calcium signals.

Migration and distribution of neural crest-derived cells in the human adrenal cortex at 9-16 weeks of gestation: an immunohistochemical study

Neural crest-derived cells are believed to migrate into the fetal adrenal cortex from the medially-located hilus. However, there appears to be a paucity of observations of the migration and distribution of medullary cells in humans. In sagittal as well as horizontal sections of human fetuses between 9 and 16 weeks of gestation, we identified chromaffin, ganglion and Schwann-like cells in the developing adrenal gland using immunohistochemistry. Cells showing tyrosine hydroxylase (TH) immunoreactivity (i.e., candidate ganglion cells) entered the fetal cortex mainly from the medial half of the adrenal, but the path of entry also included the ventral, dorsal and caudal aspects. These cells displayed linear arrangements, forming a connection between the peripheral and central areas of the gland. S100 protein-immunoreactive cells (i.e., Schwann-like cells) accompanied most (but not all) of the TH-positive cells. The distribution of chromogranin A-immunoreactive cells (i.e., chromaffin cells) was similar to and overlapped with that of TH-positive cells. Chromogranin A-positive cells were observed around the aorta as well as in the adrenal. The entry of neural crest-derived cells does not appear to be restricted to a hypothetical medial hilus, but occurs widely around the cortex, with or without the accompaniment of Schwann-like cells. These cells advance in lines through the fetal cortex in a cord-like arrangement without destruction of the cortical architecture. Some of the TH-positive cells very likely express chromogranin A before entry into the adrenal.

Simultaneous Optimization of Flight Control and Aerodynamic Shape for Aerocapture Vehicle

Aerocapture is expected to reduce the cost of the interplanetary exploration in the future because it utilizes aerodynamic drag to decelerate the vehicle rather than fuel-costly chemical propulsion. However, aerocapture mission involves lots of complicated difficulties such as quite narrow entry path angle, excess aerodynamic heating, aerodynamic load, and various uncertainties. It requires high levels of control technique and aerodynamic characteristics prediction. In this paper, the results of the simultaneous optimization of the flight control and aerodynamic shape for Mars aerocapture vehicle are presented. To maximize the payload mass, fuel mass for orbital transfer and TPS mass must be minimized. For this purpose, objective functions are set as follows: 1) minimize the delta-V for orbit insertion, 2) minimize the total heat load, 3) minimize both the delta-V and total heat load. Firstly, optimization was conducted only for the flight control, assuming the fixed aerodynamic shape and entry path angle. Secondary, simultaneous optimization was conducted. As a result, trade-off between delta-V and total heat load was clarified. Moreover, by executing simultaneous optimization, the guideline of designing aerocapture, which can minimize the objective function in each case 1)-3), was obtained.

Chagas disease, migration and community settlement patterns in Arequipa, Peru.

BackgroundChagas disease is one of the most important neglected tropical diseases in the Americas. Vectorborne transmission of Chagas disease has been historically rare in urban settings. However, in marginal communities near the city of Arequipa, Peru, urban transmission cycles have become established. We examined the history of migration and settlement patterns in these communities, and their connections to Chagas disease transmission.Methodology/Principal FindingsThis was a qualitative study that employed focus group discussions and in-depth interviews. Five focus groups and 50 in-depth interviews were carried out with 94 community members from three shantytowns and two traditional towns near Arequipa, Peru. Focus groups utilized participatory methodologies to explore the community's mobility patterns and the historical and current presence of triatomine vectors. In-depth interviews based on event history calendars explored participants' migration patterns and experience with Chagas disease and vectors. Focus group data were analyzed using participatory analysis methodologies, and interview data were coded and analyzed using a grounded theory approach. Entomologic data were provided by an ongoing vector control campaign. We found that migrants to shantytowns in Arequipa were unlikely to have brought triatomines to the city upon arrival. Frequent seasonal moves, however, took shantytown residents to valleys surrounding Arequipa where vectors are prevalent. In addition, the pattern of settlement of shantytowns and the practice of raising domestic animals by residents creates a favorable environment for vector proliferation and dispersal. Finally, we uncovered a phenomenon of population loss and replacement by low-income migrants in one traditional town, which created the human settlement pattern of a new shantytown within this traditional community.Conclusions/SignificanceThe pattern of human migration is therefore an important underlying determinant of Chagas disease risk in and around Arequipa. Frequent seasonal migration by residents of peri-urban shantytowns provides a path of entry of vectors into these communities. Changing demographic dynamics of traditional towns are also leading to favorable conditions for Chagas disease transmission. Control programs must include surveillance for infestation in communities assumed to be free of vectors.

Effect of dietary probiotics on clownfish: a molecular approach to define how lactic acid bacteria modulate development in a marine fish

We set out to determine whether probiotic addition would improve larval development in the false percula clownfish Amphiprion ocellaris and to determine what molecular responses could be observed in the larvae following probiotic exposure. We supplied the probiotic bacterial strain Lactobacillus rhamnosus IMC 501 to clownfish larvae from the first day posthatch simultaneously by live prey and with addition to rearing water (group 2) and exclusively by live prey (group 3). We observed twofold higher body weight in both clownfish larvae and juveniles when probiotics were supplied via live prey and added to the rearing water. In addition, development was accelerated with metamorphosis occurring 3 days earlier in fingerlings treated with probiotic. Alteration in molecular biomarkers supported the faster growth observation. There was significantly increased gene expression of factors involved in growth and development (insulin-like growth factors I and II, myostatin, peroxisome proliferator-activated receptors alpha and beta, vitamin D receptor alpha, and retinoic acid receptor gamma) when probiotics were delivered via live prey and added to the rearing water. Moreover, probiotic treatment lessened the severity of the general stress response as exhibited by lower levels of glucocorticoid receptor and 70-kDa heat shock protein gene expression. Furthermore, an improvement of skeletal head development was observed, with a 10-20% reduction in deformities for juveniles treated with probiotic. All data suggest a potent effect on development resulting from the administration of lactic acid bacteria to larval clownfish, and this study provides a preliminary molecular entry path into the investigation of mechanisms responsible for probiotic enhancement in fish development.

Lanthanum ions inhibit the mammalian Sec61 complex in its channel dynamics and protein transport activity

Previous electrophysiological experiments characterized the Sec61 complex, which provides the aqueous path for entry of newly-synthesized polypeptides into the mammalian endoplasmic reticulum, as a highly dynamic channel that, once activated by precursor proteins, fluctuates between main open states with mean conductances of 220 and 550 pS. Millimolar concentrations of lanthanum ions simultaneously restricted the dynamics of the Sec61 channel and inhibited translocation of polypeptides. Molecular modeling indicates that lanthanum binding sites cluster at the putative lateral gate of the Sec61 complex and suggests that structural flexibility of the lateral gate is essential for channel and protein transport activities of the Sec61 complex.

Solar wind entry via flux tube into magnetosphere observed by Cluster measurements at dayside magnetopause during southward IMF

By analyzing hot ion and electron parameters together with magnetic field measurements from Cluster, an event of magnetopause crossing of the spacecraft has been investigated. At the latitude of about 40° and magnetic local time (MLT) of 13:20 during the southward interplanetary magnetic field (IMF), a transition layer was observed, with the magnetospheric field configuration and cold dense plasma features of the magnetosheath. The particle energy-time spectrograms inside the layer were similar to but still a little different from those in the magnetosheath, obviously indicating the solar wind entry into the magnetosphere. The direction and magnitude of the accelerated ion flow implied that reconnection might possibly cause such a solar wind entry phenomenon. The bipolar signature of the normal magnetic component BN in magnetopause coordinates further supported happening of reconnection there. The solar wind plasma flowed toward the magnetopause and entered the magnetosphere along the reconnected flux tube. The magnetospheric branch of the reconnected flux tube was still inside the magnetosphere after reconnection and supplied the path for the solar wind entry into the dayside magnetosphere. The case analysis gives observational evidence and more details of how the reconnection process at the dayside low latitude magnetopause caused the solar wind entry into the magnetosphere.

Feasibility study on nearly-fuel-free planetary exploration with low-ballistic-coefficient aerocapture of sail-type vehicle

A novel concept of the nearly-fuel-free planetary exploration by the sail aerocapture vehicle, which uses the sail not only for the solar sailing but also for an aerodynamic decelerator at the orbit insertion, and its design methodology are presented. Considering a mission to Saturn, the trajectory analysis shows that the corridor of the entry path angle for successful aerocapture is significantly widened and that the aerodynamic heating is much reduced, thanks to the ultra-low ballistic coefficient of the sail-type vehicle. The coupled analyses of the rarefied flow field and the deformation of the sail demonstrate that the solar sail vehicle can survive under the condition of the aerodynamic heating and the stress due to the aerodynamic force. To sustain the disk-like shape of the sail during the atmospheric flight, an inflatable torus attached as a hoop support is recommended as well as a spin motion producing the centrifugal force.