Human dental pulp fibroblasts express the "cold-sensing" transient receptor potential channels TRPA1 and TRPM8.

Abstract
INTRODUCTION:
Transient receptor potential (TRP) channels comprise a group of nonselective calcium-permeable cationic channels, which are polymodal sensors of environmental stimuli such as thermal changes and chemicals. TRPM8 and TRPA1 are cold-sensing TRP channels activated by moderate cooling and noxious cold temperatures, respectively. Both receptors have been identified in trigeminal ganglion neurones, and their expression in nonneuronal cells is now the focus of much interest. The aim of this study was to investigate the molecular and functional expression of TRPA1 and TRPM8 in dental pulp fibroblasts.
METHODS:
Human dental pulp fibroblasts were derived from healthy molar teeth. Gene and protein expression was determined by polymerase chain reaction and Western blotting. Cellular localization was investigated by immunohistochemistry, and TRP functionality was determined by Ca(2+) microfluorimetry.
RESULTS:
Polymerase chain reaction and Western blotting showed gene and protein expression of both TRPA1 and TRPM8 in fibroblast cells in culture. Immunohistochemistry studies showed that TRPA1 and TRPM8 immunoreactivity co-localized with the human fibroblast surface protein. In Ca(2+) microfluorimetry studies designed to determine the functionality of TRPA1 and TRPM8 in pulp fibroblasts, we showed increased intracellular calcium ([Ca(2+)](i)) in response to the TRPM8 agonist menthol, the TRPA1 agonist cinnamaldehyde, and to cool and noxious cold stimuli, respectively. The responses to agonists and thermal stimuli were blocked in the presence of specific TRPA1 and TRPM8 antagonists.
CONCLUSIONS:
Human dental pulp fibroblasts express TRPA1 and TRPM8 at the molecular, protein, and functional levels, indicating a possible role for fibroblasts in mediating cold responses in human teeth.

Received signal characteristics of outdoor body-to-body communications channels at 2.45 GHz

In this paper we conduct a number of experiments to assess the impact of typical human body movements on the signal characteristics of outdoor body-to-body communications channels using flexible patch antennas. A modified log-distance path loss model which accounts for body shadowing and signal fading due to small movements is used to model the measured data. For line of sight channels, in which both ends of the body-to-body link are stationary, the path loss exponent is close to that for free space, although the received signal is noticeably affected by involuntary or physiological-related movements of both persons. When one person moves to obstruct the direct signal path between nodes, attenuation by the person's body can be as great as 40 dB, with even greater variation observed due to fading. The effects of movements such as rotation, tilt, walking in line of sight and non-line of sight on body-to-body communications channels are also investigated in this study. © 2011 IEEE.

Power allocation strategies across N orthogonal channels for single-relay networks at both source and relay

We consider a wireless relay network with one source, one relay and one destination, where communications between nodes are preformed over N orthogonal channels. This, for example, is the case when orthogonal frequency division multiplexing is employed for data communications. Since the power available at the source and relay is limited, we study optimal power allocation strategies at the source and relay in order to maximize the overall source-destination capacity. Depending on the availability of the channel state information at both the source and relay or only at the relay, power allocation is performed at both the source and relay or only at the relay. Considering different setups for the problem, various optimization problems are formulated and solved. Some properties of the optimal solution are also proved.

Ergodic Capacity of Cognitive TAS/GSC Relaying in Nakagami-m Fading Channels

We examine the impact of transmit antenna selection with receive generalized selection combining (TAS/GSC) for cognitive decode-and-forward (DF) relaying in Nakagami-m fading channels. We select a single transmit antenna at the secondary transmitter which maximizes the receive signal-to-noise ratio (SNR) and combine a subset of receive antennas with the largest SNRs at the secondary receiver. In an effort to assess the performance, we first derive the probability density function and cumulative distribution function of the end-to-end SNR using the moment generating function. We then derive new exact closed-form expression for the ergodic capacity. More importantly, by deriving the asymptotic expression for the high SNR approximation of the ergodic capacity, we gather deep insights into the high SNR slope and the power offset. Our results show that the high SNR slope is 1/2 under the proportional interference power constraint. Under the fixed interference power constraint, the high SNR slope is zero.

Predominance of entanglement of formation over quantum discord under quantum channels

We present a study of the behavior of two different figures of merit for quantum correlations, entanglement of formation and quantum discord, under quantum channels showing how the former can, counterintuitively, be more resilient to such environments spoiling effects. By exploiting strict conservation relations between the two measures and imposing necessary constraints on the initial conditions we are able to explicitly show this predominance is related to build-up of the system-environment correlations.

The Role of K+ and Cl- Channels in the Regulation of Retinal Arteriolar Tone and Blood Flow

Purpose: This study tested the role of K(+)- and Cl(-)-channels in retinal arteriolar smooth muscle in the regulation of retinal blood flow.

Methods: Studies were carried out in adult Male Hooded Lister rats. Selectivity of ion channel blockers was established using electrophysiological recordings from smooth muscle in isolated arterioles under voltage clamp conditions. Leukocyte velocity and retinal arteriolar diameters were measured in anesthetised animals using leukocyte fluorography and fluorescein angiography imaging with a confocal scanning laser ophthalmoscope. These values were used to estimate volumetric flow, which was compared between control conditions and following intravitreal injections of ion channel blockers, either alone or in combination with the vasoconstrictor potent Endothelin 1 (Et1).

Results: Voltage activated K(+)-current (IKv) was inhibited by correolide, large conductance (BK) Ca(2+)-activated K(+)-current (IKCa) by Penitrem A, and Ca(2+)-activated Cl(-)-current (IClCa) by disodium 4,4'-diisothiocyanatostilbene-2,2'-disulfonate (DIDS). Intravitreal injections (10µl) of DIDS (estimated intraocular concentration 10mM) increased flow by 22%, whereas the BK-blockers Penitrem A (1µM) and iberiotoxin (4µM), and the IKv-inhibitor correolide (40µM) all decreased resting flow by approximately 10%. Et1 (104nM) reduced flow by almost 65%. This effect was completely reversed by DIDS but was unaffected by Penitrem A, iberiotoxin or correolide.

Conclusions: These results suggest that Cl(-)-channels in retinal arteriolar smooth muscle limit resting blood flow and play an obligatory role in Et1 responses. K(+)-channel activity promotes basal flow but exerts little modifying effect on the Et1 response. Cl(-)-channels may be appropriate molecular targets in retinal pathologies characterised by increased Et1 activity and reduced blood flow.

Role of ion channels and subcellular Ca2+ signalling in arachidonic acid induced dilation of pressurised retinal arterioles

Purpose: To investigate the mechanisms responsible for the dilatation of rat retinal arterioles in response to arachidonic acid (AA). Methods: Changes in the diameter of isolated, pressurized rat retinal arterioles were measured in the presence of AA alone and following pre-incubation with pharmacological agents inhibiting Ca2+ sparks and oscillations and K+ channels. Subcellular Ca2+ signals were recorded in arteriolar myocytes using Fluo-4-based confocal imaging. The effects of AA on membrane currents of retinal arteriolar myocytes were studied using whole-cell perforated patch clamp recording. Results: AA dilated pressurised retinal arterioles under conditions of myogenic tone. Eicosatetraynoic acid (ETYA) exerted a similar effect, but unlike AA, its effects were rapidly reversible. AA-induced dilation was associated with an inhibition of subcellular Ca2+ signals. Interventions known to block Ca2+ sparks and oscillations in retinal arterioles caused dilatation and inhibited AA-induced vasodilator responses. AA accelerated the rate of inactivation of the A-type Kv current and the voltage dependence of inactivation was shifted to more negative membrane potentials. It also enhanced voltage-activated and spontaneous BK currents, but only at positive membrane potentials. Pharmacological inhibition of A-type Kv and BK currents failed to block AA-induced vasodilator responses. AA suppressed L-type Ca2+ currents. Conclusions: These results suggest that AA induces retinal arteriolar vasodilation by inhibiting subcellular Ca2+ signalling activity in retinal arteriolar myocytes, most likely through a mechanism involving the inhibition of L-type Ca2+ channel activity. AA actions on K+ currents are inconsistent with a model in which K+ channels contribute to the vasodilator effects of AA.