1,721,254 research outputs found
Temporal development of cyclic nucleotide-gated and Ca2+ -activated Cl- currents in isolated mouse olfactory sensory neurons
No full textA Ca(2+)-activated Cl(-) current constitutes a large part of the transduction current in olfactory sensory neurons. The binding of odorants to olfactory receptors in the cilia produces an increase in cAMP concentration; Ca(2+) enters into the cilia through CNG channels and activates a Cl(-) current. In intact mouse olfactory sensory neurons little is known about the kinetics of the Ca(2+)-activated Cl(-) current. Here, we directly activated CNG channels by flash photolysis of caged cAMP or 8-Br-cAMP and measured the current response with the whole cell voltage-clamp technique in mouse neurons. We measured multiphasic currents in the rising phase of the response at -50 mV. The current rising phase became monophasic in the absence of extracellular Ca(2+), at +50 mV, or when most of the intracellular Cl(-) was replaced by gluconate to shift the equilibrium potential for Cl(-) to -50 mV. These results show that the second phase of the current in mouse intact neurons is attributed to a Cl(-) current activated by Ca(2+), similarly to previous results on isolated frog cilia. The percentage of the total saturating current carried by Cl(-) was estimated in two ways: 1) by measuring the maximum secondary current and 2) by blocking the Cl(-) channel with niflumic acid. We estimated that in the presence of 1 mM extracellular Ca(2+) and in symmetrical Cl(-) concentrations the Cl(-) component can constitute up to 90% of the total current response. These data show how to unravel the CNG and Ca(2+)-activated Cl(-) component of the current rising phase
Anion Selectivity and Blockers of the Calcium-Activated Chloride Current in Mouse Olfactory Sensory Neurons
No full textCa2+-Activated Chloride Channels and Phospholipid Scramblases
Full text link: The functional characterization of the TMEM16 protein family unexpectedly brought together two different research fields in membrane biology: anion channel and membrane lipid organization [...]
Calcium-activated chloride currents in olfactory sensory neurons and in HEK293 cells heterologously expressing TMEM16B
No full textCyclic nucleotide-gated ion channels in sensory transduction
Full text linkAbstractCyclic nucleotide-gated (CNG) channels, directly activated by the binding of cyclic nucleotides, were first discovered in retinal rods, cones and olfactory sensory neurons. In the visual and olfactory systems, CNG channels mediate sensory transduction by conducting cationic currents carried primarily by sodium and calcium ions. In olfactory transduction, calcium in combination with calmodulin exerts a negative feedback on CNG channels that is the main molecular mechanism responsible for fast adaptation in olfactory sensory neurons. Six mammalian CNG channel genes are known and some human visual disorders are caused by mutations in retinal rod or cone CNG genes
Flash photolysis of caged compounds in the cilia of olfactory sensory neurons
No full textPhotolysis of caged compounds allows the production of rapid and localized increases in the concentration of various physiologically active compounds(1). Caged compounds are molecules made physiologically inactive by a chemical cage that can be broken by a flash of ultraviolet light. Here, we show how to obtain patch-clamp recordings combined with photolysis of caged compounds for the study of olfactory transduction in dissociated mouse olfactory sensory neurons
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Biomechanical effects of prosthesis neck geometries to contrast limb lengthening after hip replacement
No full textHip prostheses should meet the anatomical and physiological characteristics of patients; this is the rationale for designing
modular implants of different sizes. To optimize implant geometry, it is necessary to consider, not only the prosthesis
component design, but also the final configuration of the implanted leg. This means the necessity to consider the specific morphological
and functional condition of “that” patient and not only of “that” hip to restore, at best, limb functions. Variations
in the length of the implanted limb are frequent; therefore, the variations in the three geometrical features of the hip prosthesis
neck, which can affect the restoration of the anatomical symmetry of the limbs, were investigated: (i) neck lengths (LN), between
50.5 and 64.5 mm; (ii) cervico-diaphyseal (CD) angle (γ), between 135 and 125° and; (iii) anteversion (AV) angle (β), between
0 and 15°. Adopting a three-dimensional (3D) simplified biomechanical model, the resultant load acting on the hip was
estimated for each different design solution; corresponding stress distributions and contact pressures at the interface between the
prosthesis head and the ultra high molecular weight polyethylene (UHMWPE) layer were evaluated by 3D finite element (FE)
analyses and using the Strozzi approach. The following values have been assumed as physiological values: γ = γp = 125°, β =
βp = 15° and Ln = 57 mm; it was found that to contrast limb lengthening, if the CD angle varies from 135-125° (with neck
length Ln = 64.5 mm and AV = 0°), the joint resultant load decreases by 8.8% (7.2% if AV = 15°); the contact pressure decreases
by 5.8%, (5% if AV = 15°); the bending moment in the stem neck increases by 10.9% (13.8% if AV = 15°) and the
torque increases by 1% (12.8% if AV = 15°
A novel design of ventricular assist device: An in vitro feasibility study.
No full textLeft ventricular assist devices (LVADs) work as a bypass between the left ventricular apex and the ascending aorta. The surgical procedure for their insertion requires the opening of the cardiac cavities and the dissection of the great vessels, the blood is constrained to flow through the device components and the risk can be run of thrombogenesis, haemolysis and infections. A possible strategy to overcome this limitation consists in utilizing external systems that assist the heart in its contraction from the outside without directly transporting the blood. In this study we conduct the feasibility analysis of a novel external LVAD design that does not require the opening of the cardiac cavities and the dissection of the great vessels and that allows the removal procedure to be easily achieved. The device, including a stepper motor, three metallic wires and three elastic elements, works alternatively between a contraction condition where it induces an elastic compulsion on the heart and a release condition where it elastically releases the organ. The values of force acting on the wires and the values of current supplied to the motor were measured and utilized for a preliminary study design. The experimental measurements demonstrated the feasibility of the system
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