Chemical modulation of alveolar epithelial permeability.

The volume and composition of fluid on the surface of the alveoli can affect alveolar ventilation, gas diffusion, and macrophage function. The passive permeability and active processes of the alveolar epithelial lining play a role in regulating surface fluid and are a potential site of damage by airborne chemicals. Like other epithelial barriers, the alveolar lining is permeable to lipophilic substances but restricts the transmural flow of small ions and hydrophilic nonelectrolytes (equivalent pore radius ca. 0.5-1.5 nm). The mammalian fetal lung and alveolar sacs of the adult bullfrog secrete Cl- and K+ into the airspace. Secretion by the fetal lung ceases at birth. Many environmental agents increase the permeability of the capillary endothelium and/or respiratory epithelium and induce pulmonary edema. Studies with bullfrog alveolar sacs have demonstrated that selective effects may or may not be followed by general derangement of the epithelial barrier. Exposure of the luminal surface to HgCl2 (10(-6) to 10(-4) M) induces a selective increase in Cl- secretion that is followed by a fall in transport and a general increase in ion permeation. CdCl2 (10(-5) to 10(-3) M) depresses ciliomotion on cells on the trabecula of the alveolus but does not affect Cl- secretion or transepithelial conductance. HNO3, like other mineral acids, increases conductance and the radii or pores in the barrier, whereas NaNO3 selectively inhibits Cl- secretion. Amphotericin B(10(7) to 10(-5) MJ) induces K+ secretion into the lumen of both bullfrog and rat lung. We conclude that environmental agents induce changes in epithelial function that may compromise the lung's ability to regulate respiratory fluid without destroying the characteristic permeability of the epithelial lining

Detecting Distracted Driving with Deep Learning

© Springer International Publishing AG 2017Driver distraction is the leading factor in most car crashes and near-crashes. This paper discusses the types, causes and impacts of distracted driving. A deep learning approach is then presented for the detection of such driving behaviors using images of the driver, where an enhancement has been made to a standard convolutional neural network (CNN). Experimental results on Kaggle challenge dataset have confirmed the capability of a convolutional neural network (CNN) in this complicated computer vision task and illustrated the contribution of the CNN enhancement to a better pattern recognition accuracy.Peer reviewe

Characterization and Modeling of Local Electromechanical Response in Stress-Biased Piezoelectric Actuators

Numerous investigators have explored the factors that contribute to the high electromechanical performance of stress-biased actuators with particular attention being given to the importance of the extrinsic (domain wall translation) response mechanism. Based on the variation in lateral stress through the thickness of the piezoelectric layer within these devices, it has been suggested that the piezoelectric coefficient varies as a function of position within the layer, though no direct evidence has been previously presented. In this study, the results of Moire interferometry investigations of local strains within these devices are reviewed. The technique permits effective depth-profiling of local deformations at reasonably high (0.25 µm) resolution. A least squares regression analysis approach was used in conjunction with classical laminate theory and free edge effects to fit this experimental data to depth-dependent piezoelectric response. As expected, higher d-coefficients were predicted for the upper free surface of the device compared to the interface with the stainless steel substrate. The predicted values were in general agreement with expectation and are further considered from the perspective of recent reports in the literature regarding multi-axial loading effects on the electromechanical properties of lead zirconate titanate-based piezoelectric ceramics

A Single-Element Tuning Fork Piezoelectric Linear Actuator

This paper describes the design of a piezoelectric tuning-fork, dual-mode motor. The motor uses a single multilayer piezoelectric element in combination with tuning fork and shearing motion to form an actuator using a single drive signal. Finite-element analysis was used in the design of the motor, and the process is described along with the selection of the device\u27s materials and its performance. Swaging was used to mount the multilayer piezoelectric element within the stator. Prototypes of the 25-mm long bidirectional actuator achieved a maximum linear no-load speed of 16.5 cm/s, a maximum linear force of 1.86 N, and maximum efficiency of 18.9%

Endogenous chloride channels of insect sf9 cells. Evidence for coordinated activity of small elementary channel units

The endogenous Cl- conductance of Spodoptera frugiperda (Sf9) cells was studied 20-35 h after plating out of either uninfected cells or cells infected by a baculovirus vector carrying the cloned beta-galactosidase gene (beta-Gal cells). With the cation Tris+ in the pipette and Na+ in the bath, the reversal potential of whole-cell currents was governed by the prevailing Cl- equilibrium potential and could be fitted by the Goldman-Hodgkin-Katz equation with similar permeabilities for uninfected and beta-Gal cells. In the frequency range 0.12 < f < 300 Hz, the power density spectrum of whole-cell Cl- currents could be fitted by three Lorentzians. Independent of membrane potential, >50% of the total variance of whole-cell current fluctuations was accounted for by the low frequency Lorentzian (fc = 0.40 +/- 0.03 Hz, n = 6). Single-Cl- channels showed complex gating kinetics with long lasting (seconds) openings interrupted by similar long closures. In the open state, channels exhibited fast burst-like closures. Since the patches normally contained more than a single channel, it was not possible to measure open and closed dwell-time distributions for comparing single-Cl- channel activity with the kinetic features of whole-cell currents. However, the power density spectrum of Cl- currents of cell-attached and excised outside-out patches contained both high and low frequency Lorentzian components, with the corner frequency of the slow component (fc = 0.40 +/- 0.02 Hz, n = 4) similar to that of whole-cell current fluctuations. Chloride channels exhibited multiple conductance states with similar Goldman-Hodgkin-Katz-type rectification. Single-channel permeabilities covered the range from approximately 0.6.10(-14) cm5/s to approximately 6.10(-14) cm3/s, corresponding to a limiting conductance (gamma 150/150) of approximately 3.5 pS and approximately 35 pS, respectively. All states reversed near the same membrane potential, and they exhibited similar halide ion selectivity, P1 > PCl approximately PBr. Accordingly, Cl- current amplitudes larger than current flow through the smallest channel unit resolved seem to result from simultaneous open/shut events of two or more channel units

Status of Fluid and Electrolyte Absorption in Cystic Fibrosis

Salt and fluid absorption is a shared function of many of the body’s epithelia, but its use is highly adapted to the varied physiological roles of epithelia-lined organs. These functions vary from control of hydration of outward-facing epithelial surfaces to conservation and regulation of total body volume. In the most general context, salt and fluid absorption is driven by active Na+ absorption. Cl− is absorbed passively through various available paths in response to the electrical driving force that results from active Na+ absorption. Absorption of salt creates a concentration gradient that causes water to be absorbed passively, provided the epithelium is water permeable. Key differences notwithstanding, the transport elements used for salt and fluid absorption are broadly similar in diverse epithelia, but the regulation of these elements enables salt absorption to be tailored to very different physiological needs. Here we focus on salt absorption by exocrine glands and airway epithelia. In cystic fibrosis, salt and fluid absorption by gland duct epithelia is effectively prevented by the loss of cystic fibrosis transmembrane conductance regulator (CFTR). In airway epithelia, salt and fluid absorption persists, in the absence of CFTR-mediated Cl− secretion. The contrast of these tissue-specific changes in CF tissues is illustrative of how salt and fluid absorption is differentially regulated to accomplish tissue-specific physiological objectives

Physician–Patient Communication About Sexual Functioning in Patients with Multiple Sclerosis

Sexual dysfunction is quite common among individuals with multiple sclerosis (MS); however, severity of dysfunction alone does not account for the tremendous variation in sexual satisfaction across individuals living with MS. Individual characteristics, relationships with intimate partners, and environmental factors all likely contribute to the multidimensional experience of sexual satisfaction. Health care provider variables, including how one communicates with providers about sexual concerns, may also be influential. The purpose of this study was to examine factors that are associated with patients’ sex-related communications with their MS physicians and to overall patient sexual satisfaction. Individuals in an MS clinic (n = 73) completed a survey packet which included measures of physical and mental health, sexual dysfunction, sexual satisfaction, sex communication, health care provider relationships, and health care satisfaction. Findings suggest that while more than half of patients with MS reported experiencing sexual dysfunction, only a third of patients indicated addressing their sexual concerns with their physician during the past year. Interestingly, the frequency of communication about sexual concerns was associated with satisfaction with physician variables, whereas selfefficacy for these interactions was associated with emotional health variables. These results indicate that when considering interventions to increase confidence for communication and frequency of communication that differing factors may be taken into account

Na+ transport in cystic fibrosis respiratory epithelia. Abnormal basal rate and response to adenylate cyclase activation.

The transepithelial potential difference (PD) of cystic fibrosis (CF) airway epithelium is abnormally raised and the Cl- permeability is low. We studied the contribution of active Na+ absorption to the PD and attempted to increase the Cl- permeability of CF epithelia. Nasal epithelia from CF and control subjects were mounted in Ussing chambers and were short-circuited. The basal rate of Na+ absorption was raised in CF polyps compared with control tissues. Whereas beta agonists induced Cl- secretion in normal and atopic epithelia, beta agonists further increased the rate of Na+ absorption in CF epithelia without inducing Cl- secretion. This unusual effect is not due to an abnormal CF beta receptor because similar effects were induced by forskolin, and because cAMP production was similar in normal and CF epithelia. We conclude that CF airway epithelia absorb Na+ at an accelerated rate. The abnormal response to beta agonists may reflect a primary abnormality in a cAMP-modulated path, or a normal cAMP-modulated process in a Cl- impermeable epithelial cell

Dihydrodinophysistoxin-1 Produced by Dinophysis norvegica in the Gulf of Maine, USA and Its Accumulation in Shellfish

Dihydrodinophysistoxin-1 (dihydro-DTX1, (M-H)−m/z 819.5), described previously from a marine sponge but never identified as to its biological source or described in shellfish, was detected in multiple species of commercial shellfish collected from the central coast of the Gulf of Maine, USA in 2016 and in 2018 during blooms of the dinoflagellate Dinophysis norvegica. Toxin screening by protein phosphatase inhibition (PPIA) first detected the presence of diarrhetic shellfish poisoning-like bioactivity; however, confirmatory analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) failed to detect okadaic acid (OA, (M-H)−m/z 803.5), dinophysistoxin-1 (DTX1, (M-H)−m/z 817.5), or dinophysistoxin-2 (DTX2, (M-H)−m/z 803.5) in samples collected during the bloom. Bioactivity-guided fractionation followed by liquid chromatography-high resolution mass spectrometry (LC-HRMS) tentatively identified dihydro-DTX1 in the PPIA active fraction. LC-MS/MS measurements showed an absence of OA, DTX1, and DTX2, but confirmed the presence of dihydro-DTX1 in shellfish during blooms of D. norvegica in both years, with results correlating well with PPIA testing. Two laboratory cultures of D. norvegica isolated from the 2018 bloom were found to produce dihydro-DTX1 as the sole DSP toxin, confirming the source of this compound in shellfish. Estimated concentrations of dihydro-DTX1 were \u3e0.16 ppm in multiple shellfish species (max. 1.1 ppm) during the blooms in 2016 and 2018. Assuming an equivalent potency and molar response to DTX1, the authority initiated precautionary shellfish harvesting closures in both years. To date, no illnesses have been associated with the presence of dihydro-DTX1 in shellfish in the Gulf of Maine region and studies are underway to determine the potency of this new toxin relative to the currently regulated DSP toxins in order to develop appropriate management guidance