bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel oxygen‐sensitive potassium current in rat carotid body type I cells.
Authors: Buckler K J
Published: December 2014

1. Hypoxic stimuli depolarize carotid body type I cells causing voltage‐gated calcium influx. This study investigates the cause of this membrane depolarization. Isolated type I cells from neonatal (11‐16 day) rat carotid bodies were used in the experiments. 2. Tetraethylammonium (TEA; 10 mM), 1 and 5 mM 4‐aminopyridine (4‐AP) and 20 nM charybdotoxin all failed to evoke a significant rise in [Ca2+]i. Similarly, in perforated patch whole‐cell recordings, a combination of 10 mM TEA and 5 mM 4‐AP failed to depolarize type I cells. 3. In type I cells voltage clamped at ‐70 mV, anoxia evoked a small inward current under control conditions, but had no effect in the absence of pipette and extracellular K+. 4. Anoxia decreased resting membrane conductance from 322 to 131 pS. The anoxia‐sensitive current (measured using voltage ramps from ‐100 to ‐40 mV) had a reversal potential of ‐89 mV in 4.5 mM Ko+ and ‐66 mV in 20 mM Ko+, indicating that this current was carried principally by potassium ions. In contrast, 10 mM TEA + 5 mM 4‐AP had little effect on the current‐voltage relationship of the cells over the same range. 5. This O2‐sensitive K+ conductance showed only mild outward rectification over the range ‐90 to +30 mV, which could be approximated by the Goldman‐Hodgkin‐Katz current equation. In addition, there was no time‐dependent activation or inactivation of membrane currents elicited by voltage steps in the range ‐100 to ‐30 mV. 6. The O2‐sensitive K+ conductance was inhibited by graded reductions in PO2 to 40 Torr and below, with a K1/2 of about 12 Torr. 7. The data suggest that hypoxia depolarizes type I cells principally through the inhibition of a small voltage‐insensitive resting (or background) K+ conductance, and not through the inhibition of voltage‐gated TEA and 4‐AP‐sensitive K+ channels (e.g. maxi‐K or KO2 channels), as has been previously suggested.
Variation in expression of the outer hair cell P2X receptor conductance along the guinea‐pig cochlea.
Authors: Raybould N P , Housley G D
Published: December 2014

1. Whole‐cell patch‐clamp recordings were used to determine the variation in the P2X receptor conductance, activated by extracellular ATP, in outer hair cells (OHCs) isolated from each of the four turns of the guinea‐pig cochlea. 2. In standard solution (containing 1.5 mM Ca2+) slope conductances were determined in OHCs of known origin from current‐voltage relationships obtained from voltage ramps applied between ‐100 and +50 mV. Membrane conductance throughout this voltage range was greatest in OHCs originating from the basal (high frequency encoding) region of the cochlea. This gradient in OHC conductance from apex to base of the cochlea can be attributed to variation in expression of both a negatively activated K+ conductance and a TEA‐sensitive outwardly rectifying K+ conductance. OHC slope conductance measured about a membrane potential of ‐75 mV increased from a mean of 33.5 nS in the apical region (turn 4) to 96.8 nS in the basal region (turn 1) of the cochlea. 3. Removal of external Ca2+ reduced OHC conductance by an average of 25%, reflecting a Ca2+ dependence of the background conductances in these cells. In zero external Ca2+ the mean slope conductance measured at ‐75 mV in the apical turn was 25.0 nS compared with 73.8 nS in the basal turn. 4. In Ca(2+)‐free solution both 2 mM and 4 microM ATP produced inward currents that were progressively larger in OHCs originating from more basal regions of the cochlea. The steady‐state inward current elicited by 2 mM extracellular ATP increased from ‐1.44 to ‐3.26 nA for turns 4 and 1, respectively. 5. The P2X receptor conductance was determined between ‐100 and +50 mV by comparing voltage ramps in the presence and absence of extracellular ATP in Ca(2+)‐free solution. The conductance was inwardly rectifying with a reversal potential close to 0 mV. Measured close to the resting membrane potential of the cells (‐75 mV), 2 mM ATP elicited an average 300% increase in conductance in parallel with the systematic increase in background conductance which occurs in OHCs originating from the more basal regions of the cochlea. The conductance at ‐75 mV activated by 2 mM ATP increased from a mean of 59.6 nS in turn 4 OHCs to a mean of 166.2 nS in turn 1 OHCs. The conductance activated by 4 microM ATP was also greater in the basal turn OHCs (45.3 nS) than in the apical region OHCs (5.9 nS). 6. The number of ATP‐gated ion channels on individual OHCs, presumed to be localized to the stereocilia, increases from approximately 6000 in turn 4 cells to 16,500 in turn 1 cells, based on estimates of unitary conductance and average maximum ATP‐activated OHC conductance (2 mM ATP).
G protein‐dependent inhibition of L‐type Ca2+ currents by acetylcholine in mouse pancreatic B‐cells.
Authors: Gilon P , Yakel J , Gromada J , Zhu Y , Henquin J C , Rorsman P
Published: December 2014

1. The effect of acetylcholine (ACh) on voltage‐dependent Ca2+ currents in mouse pancreatic B‐cells was studied using the whole‐cell configuration of the patch‐clamp technique. 2. ACh (0.25‐250 microM) reversibly and dose‐dependently inhibited the Ca2+ current elicited by depolarizations from ‐80 mV to +10 mV. Maximal inhibition was observed at concentrations > 25 microM where it amounted to approximately 35%. The effect was voltage independent and prevented by atropine (10 microM) suggesting that it was mediated by muscarinic receptors. 3. The inhibitory action of ACh on the Ca2+ current was abolished when the cytoplasmic solution contained GDP beta S (2 mM) and became irreversible when the non‐hydrolysable GTP analogue GTP gamma S (10 microM) was included in the pipette. This indicates the participation of G proteins in the inhibitory effect of ACh but pretreatment of the cells with either pertussis or cholera toxin failed to prevent the effect of ACh on the Ca2+ current. 4. ACh remained equally effective as an inhibitor of the whole‐cell Ca2+ current in the presence of the L‐type Ca2+ channel agonist (‐)‐Bay K 8644 and after partial inhibition of the current by nifedipine. Addition of omega‐agatoxin IVA, omega‐conotoxin GVIA or omega‐conotoxin MVIIC neither affected the peak Ca2+ current amplitude nor the extent of inhibition produced by ACh. These pharmacological properties indicate that ACh acts by inhibiting L‐type Ca2+ channels. 5. The inhibitory action of ACh on the B‐cell Ca2+ current was not secondary to elevation of [Ca2+]i and ACh remained equally effective as an inhibitor when Ba2+ was used as the charge carrier, when [Ca2+]i was buffered to low concentrations using EGTA and under experimental conditions preventing the mobilization of Ca2+ from intracellular stores. 6. These results suggest that ACh reduces the whole‐cell Ca2+ current in the B‐cell through a G protein‐regulated, voltage‐ and Ca(2+)‐independent inhibition of L‐type Ca2+ channels.
Rebound stimulation of the cAMP‐regulated Cl‐ current by acetylcholine in guinea‐pig ventricular myocytes.
Authors: Zakharov S I , Harvey R D
Published: December 2014

1. Acetylcholine (ACh)‐induced rebound stimulation of the cAMP‐regulated Cl‐ current was studied in isolated guinea‐pig ventricular myocytes using dialysing and dialysis‐limiting configurations of the whole‐cell patch‐clamp technique. 2. Exposure to and subsequent washout of ACh produced a transient rebound stimulation of the Cl‐ current. However, this rebound response was only observed in the presence of submaximally stimulating concentrations of the cAMP‐producing agonists isoprenaline (Iso) or histamine. ACh‐induced rebound stimulation was not observed in the presence of maximally stimulating concentrations of Iso, nor was it observed in the absence of Iso. 3. To prevent saturation of responses during rebound, the effects of ACh were studied in the presence of a subthreshold concentration of Iso (0.001 microM). Varying the duration of exposure to ACh before washout demonstrated that the stimulatory effect of 1 microM ACh approaches steady state with a time constant of 34 s. Exposing myocytes to varying concentrations of ACh for 90 s demonstrated that the EC50 for the stimulatory effect of ACh was 0.15 microM with a maximum response equal to 67% of that obtained by a maximally stimulating concentration of Iso alone. 4. Rebound stimulation of the Cl‐ current could also be elicited by washing in 2 microM atropine during exposure to ACh, instead of washing out ACh. Furthermore, ACh‐induced rebound was blocked by the M2 muscarinic receptor antagonist methoctramine but not by the M1 receptor antagonist pirenzepine. Rebound was also blocked in pertussis toxin (PTX)‐treated myocytes. 5. ACh‐induced rebound stimulation was not blocked by: (a) L‐NMMA, an inhibitor of nitric oxide synthase activity; (b) Methylene Blue, LY‐83583, and ODQ, inhibitors of cGMP production; or (c) milrinone, an inhibitor of cGMP‐dependent phosphodiesterase activity. 6. These results indicate that ACh can stimulate cAMP‐regulated ion channel activity in cardiac ventricular myocytes by facilitating beta‐adrenergic and histaminergic responses. This is opposite to the inhibitory actions more typically associated with muscarinic receptor stimulation in ventricular myocardium. This stimulatory effect of ACh is mediated through M2 muscarinic receptors and a PTX‐sensitive G‐protein, but it does not appear to involve the production of nitric oxide or cGMP.
Glutamate receptor‐mediated synaptic excitation in axons of the lamprey.
Authors: Cochilla A J , Alford S
Published: December 2014

1. Spontaneous and evoked synaptic inputs were recorded in vitro in the axons of lamprey reticulospinal neurones. After isolation of the axon from its somata, synaptic inputs were recorded using microelectrode and whole‐cell patch clamp recording techniques. 2. Single stimuli applied to the spinal cord elicited Ca(2+)‐dependent synaptic potentials with short latencies in reticulospinal axons. These synaptic inputs are capable of summation and generate sufficient depolarization to raise the membrane potential beyond threshold to initiate action potentials. Action potential initiation in the absence of the cell body indicates that these axons show synaptic integration. 3. Both evoked and spontaneous responses comprise at least two components of synaptic drive: a slow component (rise time of 9.6 +/‐ 2.1 ms) with a reversal potential of ‐53 +/‐ 19 mV and a fast component (rise time as fast as 0.85 ms) with a reversal potential of 0.3 +/‐ 9.1 mV. The responses are Ca2+ dependent, and are blocked by the substitution of Ba2+ for Ca2+ in the saline solution. 4. The slow component of synaptic input was blocked by the gamma‐aminobutyric acidA (GABAA) receptor antagonist bicuculline (5 microM). The fast component was blocked by the alpha‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) receptor antagonist 6‐cyano‐7‐nitroqinoxaline‐2,3‐dione (CNQX; 10 microM) in Ringer solution containing physiological concentrations of Mg2+. Following removal of Mg2+ from the superfusate a further excitatory component was identified that was blocked by application of the N‐methyl‐D‐aspartate (NMDA) receptor antagonist 2‐amino‐5‐phosphonopentanoate (AP5; 100 microM). 5. Comparison of the kinetic properties and the voltage sensitivity of the isolated components of evoked and spontaneous synaptic activity indicate that these responses are mediated by similar synaptic inputs. 6. These results suggest that axons and presynaptic terminals receive excitatory and inhibitory ionotropic receptor‐mediated inputs. Summation of these inputs is possible indicating that the axons act as sites of synaptic integration similar to the role previously attributed only to neuronal dendrites and somata.
Bursts of action potential waveforms relieve G‐protein inhibition of recombinant P/Q‐type Ca2+ channels in HEK 293 cells.
Authors: Brody D L , Patil P G , Mulle J G , Snutch T P , Yue D T
Published: December 2014

1. A variety of neurotransmitters act through G‐protein‐coupled receptors to decrease synaptic transmission, largely by inhibiting the voltage‐gated calcium channels that trigger neurotransmitter release. However, these presynaptic calcium channels are typically inaccessible to electrophysiological characterization. We have reconstituted a part of this inhibition using recombinant P/Q‐type calcium channels and M2 acetylcholine receptors in HEK 293 cells. 2. One of the most interesting features of G‐protein inhibition of calcium channels is that strong step depolarization transiently relieves the inhibition. We have found that short bursts of action potential voltage waveforms can also relieve the inhibition, increasing calcium current through G‐protein‐inhibited channels but not through uninhibited channels. 3. The extent of this relief increased linearly with the duration of the action potential waveforms. 4. This result provides the strongest evidence to date favouring the possibility that relief of G‐protein inhibition can occur during high frequency trains of action potentials. This effect may constitute a novel form of short‐term synaptic plasticity that is sensitive to action potential timing and duration.
Selective downregulation of an inactivating K+ conductance by analogues of cAMP in mouse Schwann cells.
Authors: Despeyroux S , Beaudu-Lange C , Coles J A , Amédée T
Published: December 2014

1. Voltage‐dependent K+ conductances on Schwann cells in organotypic cultures of mouse dorsal root ganglia were classified as inactivating or sustained (responsible for currents IA and IK, respectively). IA is known to be much reduced on Schwann cells that contact neurites. 2. In the absence of neurones, IA and IK were present. IA, but not IK, was markedly reduced (by 80% after 105 h of treatment) by 2 mM 8‐(4‐chlorophenylthio)‐cAMP (cpt‐cAMP), a weakly hydrolysable analogue of cAMP. The effect did not appear for at least 2 h and was maximal after about 100 h. 3. The effect of 1 mM cpt‐cAMP was abolished in the presence of an inhibitor of protein kinases, N‐[2‐bromocinnamyl(amino)ethyl]‐5‐isoquinolinesulphonamide (H‐89, 10 microM). 4. Other analogues of cAMP, but not an analogue of cGMP (8‐bromo‐cGMP), also reduced IA. 5. We conclude that IA, but not IK, can be downregulated by activation of the protein kinase A pathway.
Individual differences in breathlessness during exercise, as related to ventilatory chemosensitivities in humans.
Authors: Takano N , Inaishi S , Zhang Y
Published: December 2014

1. The present study attempted to test the hypothesis that breathlessness associated with exercise hyperpnoea is greater in subjects with greater activities of the central and peripheral chemoreceptors during exercise. The chemoreceptor activities were assessed by resting estimates of hypercapnic ventilatory response (delta VE/delta PCO2, HCVR) and hypoxic ventilatory response (delta VE/‐delta SO2, HVR), respectively, where VE is minute ventilation and SO2 is oxygen saturation. 2. Nine female and nine male subjects performed a 1 min incremental exercise test until exhaustion, during which breathlessness intensity (BS), assessed by a Borg category scale, and VE were measured every minute. The maximum O2 uptake (VO2,max) was also determined. 3. Using a stepwise multiple linear regression analysis, the relative contributions of not only VE, HCVR and HVR, but also VO2,max and a predicted maximum voluntary ventilation (MVVp) of the individuals to BS, were examined. 4. The analysis showed that BS = 0.1VE + 4.9HVR ‐ 0.03MVVp + 0.55 (r2 = 0.71), indicating that VE accounted for 44% of the variance of BS, HVR for 12% and MVVp for 15%. No significant relation of HCVR and VO2,max to BS was found. 5. These results suggest a contribution of peripheral chemoreceptors to the generation of exertional breathlessness.
The role of active transport in potassium reabsorption in the proximal convoluted tubule of the anaesthetized rat.
Authors: Wilson R W , Wareing M , Green R
Published: December 2014

1. We have previously assessed the contributions of diffusion and convection to net potassium reabsorption in the rat proximal convoluted tubule (PCT). The present study was conducted to evaluate the role of active transport in convective potassium reabsorption by measuring the transepithelial potassium reflection coefficient (sigmaK) in the presence and absence of cyanide in anaesthetized rats previously prepared for in vivo microperfusion. 2. Osmotic water permeability (Pf) was measured in double‐perfused tubules (lumen and peritubular capillaries) by manipulating the applied transepithelial osmotic gradient between ‐30 and +40 mosmol (kg H2O)(‐1) using raffinose added to or subtracted from luminal perfusates. Pf was unaffected by the presence of cyanide when the estimated dissipation of osmotic gradients along each tubule were taken into account. 3. The proportion of K+ (and Na+) convectively transported with water fluxes (i.e. sigmaK) was not affected by cyanide. In the absence of active transport and following correction for any diffusive component, sigmaK was 0.56 +/‐ 0.13, indicating substantial solvent drag which probably occurs via the paracellular pathway. 4. However, cyanide caused a reduction in net potassium flux over the entire range of fluid fluxes used in double‐perfusion experiments. Subsequent single‐perfusion experiments (tubule lumen only) using the specific K+‐H+‐ATPase inhibitor, SCH28080, failed to reveal any direct evidence for a primary active K+ transporting mechanism involved in K+ reabsorption in the PCT.
Tendon organ sensitivity to steady‐state isotonic contraction of in‐series motor units in feline peroneus tertius muscle.
Authors: Petit J , Scott J J , Reynolds K J
Published: December 2014

1. Measurements have been made of the sensitivity of tendon organs to steady‐state, isotonic contractions of single and groups of in‐series motor units in the peroneus tertius muscle of the cat hindlimb. 2. Linear relationships were found between the Ib afferent discharge and the contractile tension generated by tetanic stimulation of single motor units. These relationships held for the fast, fatiguable (FF) units and for all but the lowest tensions generated by the slow (S) and some fast, fatigue resistant (FR) units. The sensitivity of the organs was independent of the contractile properties of the units. 3. Groups of three motor units were stimulated isotonically at low rates (around 30 Hz), but asynchronously to produce a smooth tension profile. Again, linear relationships pertained between the discharge rate and the tension, and the sensitivity was the same for different motor unit types. 4. Under isotonic conditions, therefore, the tendon organs showed linear responses to the tension with similar sensitivities, indicating that tendon organs may have the capacity to signal faithfully steady‐state contractile tensions.
Co‐ordination of contractile activity in guinea‐pig mesenteric lymphatics.
Authors: Crowe M J , von der Weid P Y , Brock J A , Van Helden D F
Published: December 2014

1. Intraluminally perfused lymphatic vessels from the mesentery of the guinea‐pig were examined in vitro to investigate their contractile activity and the co‐ordination of this activity between adjacent lymphangions. 2. Lymphangions constricted at fairly regular intervals and exhibited ‘refractory’ periods of up to 3 s during which constrictions did not occur. 3. The contractile activity of adjacent lymphangions was highly co‐ordinated. 4. The smooth muscle was found to be continuous between the adjacent lymphangions for the majority of valve regions examined morphologically (52 of 63 preparations). 5. Mechanical and electrical coupling between adjacent lymphangions was indicated, as some lymphangions underwent transient dilatations just prior to constriction, whereas direct electrophysiological measurements showed that the smooth muscle of most adjacent lymphangions was electrically coupled across the valve (15 out of 20 pairs of lymphangions). 6. It is concluded that perfused lymphangions of guinea‐pig mesenteric lymphatic vessels rhythmically constrict, with the contractile activity of adjacent lymphangions highly co‐ordinated. The findings also indicate that transmission of both mechanical and electrical signals between the adjacent lymphangions contribute to the co‐ordination of their contractile activity.
On the intercostal muscle compensation for diaphragmatic paralysis in the dog.
Authors: Brichant J F , De Troyer A
Published: December 2014

1. Paralysis of the diaphragm in the dog is known to cause a compensatory increase in activation of the inspiratory intercostal muscles (parasternal intercostals, external intercostals, and levator costae). The present studies were designed to assess the mechanism(s) of that compensation. 2. Complete, selective diaphragmatic paralysis was induced by injecting local anaesthetic into small silicone cuffs placed around the phrenic nerve roots in the neck. 3. Paralysis produced a decrease in tidal volume and an increase in arterial P(CO2) (P(a,CO2)). The increased hypercapnic drive was a primary determinant of the increased inspiratory intercostal activity. 4. However, paralysis also produced an increased inspiratory cranial displacement of the ribs. When this increased rib displacement was reduced to that seen before paralysis, it appeared that the increase in external intercostal and levator costae inspiratory activity was commonly greater than anticipated on the basis of the increased P(a,CO2). 5. Diaphragmatic paralysis after bilateral vagotomy also elicited disproportionate increases in inspiratory intercostal activity, thus indicating that these increases are not caused by vagal afferent inputs. 6. These observations are consistent with the idea that the intercostal muscle compensation for diaphragmatic paralysis is, in part, due to the release of an inhibition originating from the contracting diaphragm. This inhibition might arise in the diaphragmatic tendon organs.
Effects of acute changes in oestrogen on muscle function of the first dorsal interosseus muscle in humans.
Authors: Greeves J P , Cable N T , Luckas M J , Reilly T , Biljan M M
Published: December 2014

1. To investigate the effect of the female reproductive hormones on muscle function, patients undergoing in vitro fertilization were tested during two phases of treatment. The first was following the downregulation of pituitary gonadotrophin releasing hormone (GnRH) receptors and the second after 9 days of gonadotrophin injections. 2. Maximal strength and fatiguability of the first dorsal interosseus muscle were assessed when oestrogen and progesterone were low, and less than 2 weeks later when oestrogen production reached supraphysiological levels. 3. There were no significant changes in either strength or fatigue resistance during acute, massive fluctuations in oestrogen. These results occurred at a time when progesterone levels remained relatively low. 4. Contrary to previous work, the present results suggest that oestrogen does not affect muscle strength.
Effects of lactate on the relative contribution of Ca2+ extrusion mechanisms to relaxation in guinea‐pig ventricular myocytes.
Authors: Terracciano C M , MacLeod K T
Published: December 2014

1. The aim of this study was to investigate the effects of 20 mM extracellular lactate on Ca2+ regulation mechanisms in enzymatically isolated single guinea‐pig cardiac myocytes. 2. The activities of the Ca2+ regulation mechanisms during application of lactate were studied using rapid cooling contractures (RCCs) and fast application of caffeine. Cytoplasmic Ca2+ was monitored using the fluorescent indicator indo‐1. 3. After application of 20 mM lactate for 5 min, the diastolic level of Ca2+ was increased. The change in cytoplasmic Ca2+ elicited by stimulation (Ca2+ transient) was also changed. With lactate, the amplitude of the Ca2+ transient was smaller, and its time course was slower compared with control. 4. The recovery of cytoplasmic Ca2+ during rewarming after rapid cooling in lactate was slower than under control conditions. When the rewarming was performed either in Na(+)‐ and Ca(2+)‐free solution or in the presence of 10 mM caffeine, the rate of recovery of cytoplasmic Ca2+ in lactate was slower than under control conditions, suggesting that the activity of both SR Ca2+ uptake and Na(+)‐Ca2+ exchange is affected by lactate. 5. Cytoplasmic Ca2+ recovery during application of 10 mM caffeine in lactate was slower than in the control. The rate of recovery of the caffeine‐induced transient inward current was also slower supporting the hypothesis of a slower Ca2+ extrusion brought about by Na(+)‐Ca2+ exchange. 6. The relative contribution of the Ca2+ extrusion mechanisms in the presence of lactate was investigated using paired RCCs. In lactate, a second RCC (RCC2) induced immediately after recovery from the first (RCC1) was greatly reduced compared with the control. RCC2/RCC1 x 100 in lactate was 39% and RCC2/RCC1 x 100 in control conditions was 60%, suggesting that the net sarcoplasmic reticulum Ca2+ uptake is smaller in the presence of lactate. 7. When Na(+)‐free Ca2+ solution was used during the paired RCCs and rewarming, RCC2/RCC1 x 100 was increased to 96 and 95% in lactate and control conditions, respectively, implying that Ca2+ efflux from the cell can be maintained by the Na(+)‐Ca2+ exchanger and that other Ca2+ removal mechanisms (mitochondria and sarcolemmal Ca(2+)‐ATPase) remain largely unchanged in the presence of lactate.
Integrated phrenic responses to carotid afferent stimulation in adult rats following perinatal hyperoxia.
Authors: Ling L , Olson E B , Vidruk E H , Mitchell G S
Published: December 2014

1. Hypoxic ventilatory responses are greatly attenuated in adult rats exposed to moderate hyperoxia (60% O2) during the first month of life (perinatal treated rats). The present study was designed to test the hypothesis that perinatal hyperoxia impairs central integration of carotid chemoreceptor afferent inputs, thereby diminishing the hypoxic ventilatory response. 2. Time‐dependent phrenic nerve responses to electrical stimulation of the carotid sinus nerve (CSN) and steady‐state relationships between CSN stimulation frequency and phrenic nerve output were compared in control and perinatal treated rats. The rats were urethane anaesthetized, vagotomized, paralysed and artificially ventilated. End‐tidal CO2 was monitored and maintained at isocapnic levels; arterial blood gases were determined. 3. Two stimulation protocols were used: (1) three 2 min episodes of CSN stimulation (20 Hz, 0.2 ms duration, 3 x threshold), separated by 5 min intervals; and (2) nine 45 s episodes of CSN stimulation with stimulus frequencies ranging from 0.5 to 20 Hz (0.2 ms duration, 3 x threshold), separated by 4 min intervals. 4. The mean threshold currents to elicit phrenic responses were similar between groups. Burst frequency (f, burst min‐1), peak amplitude of integrated phrenic activity (integral of Phr), and minute phrenic activity (integral of Phr x f) during and after CSN stimulation were not distinguishable between groups in either protocol at any time or at any stimulus intensity (P > 0.05). 5. Perinatal hyperoxia does not alter temporal or steady‐state phrenic responses to CSN stimulation, suggesting that the central integration of carotid chemoreceptor afferent inputs is not impaired in perinatal treated rats. It is speculated that carotid chemoreceptors per se are impaired in perinatal treated rats.
Atomistic Study of the Thermal Stress due to Twin Boundaries
Authors: Chen Dengke , Kulkarni Yashashree
Published: December 2014

There is compelling evidence for the critical role of twin boundaries in imparting the extraordinary combination of strength and ductility to nanotwinned metals. This paper presents a study of the thermal expansion of coherent twin boundaries (CTBs) at finite temperature by way of atomistic simulations. The simulations reveal that for all twin boundary spacings d, the thermal expansion induced stress varies as 1/d. This surprisingly long-range effect is attributed to the inhomogeneity in the thermal expansion coefficient due to the interfacial regions.
Integration of a Pulsating Heat Pipe in a Flat Plate Heat Sink
Authors: Hoesing Mitchell P. , Michna Gregory J.
Published: December 2014

The ongoing development of faster and smaller electronic components has led to a need for new technologies to effectively dissipate waste thermal energy. The pulsating heat pipe (PHP) shows potential to meet this need, due to its high heat flux capacity, simplicity, and low cost. A 20-turn flat plate PHP was integrated into an aluminum flat plate heat sink with a simulated electronic load. The PHP heat sink used water as the working fluid and had 20 parallel channels with dimensions 2 mm × 2 mm × 119 mm. Experiments were run under various operating conditions, and thermal resistance of the PHP was calculated. The performance enhancement provided by the PHP was assessed by comparing the thermal resistance of the heat sink with no working fluid to that of it charged with water. Uncharged, the PHP was found to have a resistance of 1.97 K/W. Charged to a fill ratio of approximately 75% and oriented vertically, the PHP achieved a resistance of .49 K/W and .53 K/W when the condenser temperature was set to 20°C and 30°C, respectively. When the PHP was tilted to 45° above horizontal the PHP had a resistance of .76 K/W and .59 K/W when the condenser was set 20°C and 30°C, respectively. The PHP greatly improves the heat transfer properties of the heat sink compared to the aluminum plate alone. Additional considerations regarding flat plate PHP design are also presented.
A CFD Study on Film Thickness, Pressure Drop, and Heat Transfer of Slug Flows in Circular Microchannels
Authors: Talimi Vandad , Muzychka Yuri S. , Kocabiyik Serpil
Published: December 2014

Slug flows in microchannels have been studied in the past two decades as a method to enhance heat transfer. Several correlations have been developed for predicting film thickness, pressure drop, and heat transfer, mostly based on experimental analysis. More recently, numerical simulation become an available tool providing deeper insight of these flows. In the present study, a number of numerical simulations of slug flows performed under different wall thermal conditions, the results have been compared to the available correlations, and gaps in existing models have been highlighted. The simulations have been carried out using the commercial package ANSYS Fluent. Film thickness, pressure drop, and heat transfer models under constant wall heat flux and constant temperature have been focused, and finally suggestion for future studies have been presented.
Energy Equation of Gas Flow With Low Velocity in a Micro-Channel
Authors: Asako Yutaka
Published: December 2014

The energy equation for incompressible flow with the viscous dissipation term is often used for the governing equations of gas flow with low velocity in micro-channels. However, the results which are obtained by solving these equations do not satisfy the first law of the thermodynamics. In the case of ideal gas with low velocity, the inlet and the outlet temperatures of an adiabatic channel are the same based on the first law of the thermodynamics. However, the outlet temperature which is obtained by solving the energy equation for incompressible flow with the viscous dissipation term is higher than the inlet gas temperature, since the viscous dissipation term takes positive value. This inconsistency arose from wrong choice of the relation between the enthalpy and temperature that resulted in neglecting the substantial derivative of pressure term in the energy equation. In this paper the correct energy equation which includes the substantial derivative of pressure term is proposed. Some samples of physically consistent results which are obtained by solving the proposed energy equation are demonstrated.
Water Molecule Adsorption on Vertically Aligned Single-Walled Carbon Nanotubes
Authors: Moroizumi Hiroyuki , Chiashi Shohei , Takata Yasuyuki , Kohno Masamichi
Published: December 2014

A single walled carbon nanotube, which adsorbed water molecule in its nano channel, was observed using Raman spectroscopy, and two samples’ spectrums were compared under the same conditions. The SWNT samples that were vertically aligned on the silicon substrate were used. One of the samples was not covered by polymer whereas the other sample was covered by polymer.

In our experiment, a nano channel was made using a nanosecond pulse laser (Nd:YAG laser). In order to adjust the focus, the sample was set on the automatic stage and controlled on the PC using a USB camera to watch closely. By moving the stage for over 30 seconds, the sample was processed to make the nano channel.

The cell with the laser-processed sample in it was set on the Raman spectroscopy’s platform. Then, the cell was connected to the vacuum chamber and erlenmeyer flask by the valve. Both of the valves were opened first and left for a while to make the cell vacuum. Second, the vacuum chamber’s valve was closed and left for a while to let water molecule spread in the cell. Finally, the SWNT successfully adsorbed water molecule in its nano channel.

Ar-ion laser was used in the Raman spectroscopy and the laser wavelength is 488nm. With the Raman spectroscopy, Radial Breathing Mode (RBM), D-band, and G-band were mainly observed. The RBM, D-band, and G-band originated from radial vibration frequency, defective structure, and graphite structure respectively. According to the sample types, the RBM spectrums were compared in our experiment.
Aerosol Particle Impaction on Fiber Arrays in a Flow Stream Using a Lattice Boltzmann Model
Authors: Lee Kuan-Wei , Lin Kuang C.
Published: December 2014

Transport of aerosol particles is of great interest for theory and applications of fibrous filters. Understanding how to design better filters can help for future implementation in the areas of air cleaning and air conditioning. The aim of this paper is to present a 2-D computational model of particle-laden flows over staggered fibers at a Reynolds number of 100 using a Lattice Boltzmann method. A Lagrangian analysis is used to predict the particle impaction on a multi-fiber filter. After an initial validation of the model, the characteristic of particle impaction on fibers in staggered arrangements is then examined as a function of the particle size from 10 nm–20 μm. Each particle in gas-rich dilute phase is transported under the action of the drag, Saffman lift, gravity and Brownian forces. The number of particles impacting each fiber is locally examined. In addition, we investigate the effect of fiber geometry on the characteristic of particle impaction. These results also highlight the range of particle dimensions where the impaction can be affected by the arrangement of fibers placed in the filter.
Copper Plated Microchannel Heat Exchanger for MEMS Application
Authors: Borquist E. , Ogbonnaya E. , Thapa S. , Wood D. , Weiss L.
Published: December 2014

Demand for increased density circuit architecture, micro- and nano-scale devices, and the overall down-scaling of system components has driven research into understanding transport phenomena at reduced scales. One method to enhance transport processes is the utilization of mini-, micro-, or nano-channels which drive uniform temperature and velocity profiles throughout the system. This work specifically examines a unique heat exchanger. The exchanger is developed as a closed system, with 300μm width channels, fabricated entirely with copper.

The heat exchanger has been designed for widespread use in varied environments. Further, the exchanger is working fluid non-specific, allowing for different fluids to be specified for various temperature ranges. The system design can be used equally well as a standalone heat exchanger or coupled with another device to provide a thermal energy storage system.

Fabricating the heat exchanger with copper for the substrate as well as the channels themselves allows the exchanger to maintain a high thermal conductivity which aides in the fluid energy transference. The exchanger was fabricated to be a closed system removing any excess equipment such as pumps. In testing, the exchanger showed thermal absorption of 2.2kW/m2 given input of 2.63kW/m2 and working fluid amounts of 37μL. The general design and use of copper in the exchanger allowed maximum absorption of 84% of the input with operation below the boiling point of the working fluid.
Altering Bubble Dynamics via Vapor Extraction
Authors: Fox Randall G. , Juarez Corey D. , Pence Deborah V. , Liburdy James A.
Published: December 2014

Bubble dynamics in the presence of a porous confining surface through which vapor is extracted was experimentally investigated. Using a pulsed laser operating at 3500 pulses per second (pps), bubbles were generated at a single, 30 μm diameter nucleation site in a silicon disk. A time-averaged heat flux of 80 W/cm2 and a constant pressure differential of 35 kPa across a porous surface were maintained. The surface, a supported porous Teflon® membrane, has a nominal porosity of 55% and pore diameter of 0.45μm. Steady-state heating was achieved as determined from a one-dimensional conduction model yielding a dimensionless surface temperature fluctuations of less than 0.01%. Bubble diameter and frequency were determined using high-speed imaging for ten gap heights ranging between 0.52 mm and 3.99 mm, where the gap height is defined as the distance between the heated surface and the confining surface. Bubble dynamics of freely departing, coalescing, and rupturing bubbles are considered. Results are compared to diameters and frequencies achieved in unconfined (i.e. pool boiling) conditions. Isolated bubble dynamics depend on gap height and can be grouped into three ranges: greater than, equal to, and less than the bubble diameters for unconfined conditions, which for the present conditions is 1.53 mm. This paper is a work in progress.
Comparing nonrigid registration techniques for motion corrected MR prostate diffusion imaging
Authors: Buerger C. , Sénégas J. , Kabus S. , Carolus H. , Schulz H. , Agarwal H. , Turkbey B. , Choyke P. L. , Renisch S.
Published: December 2014

Purpose:

T2‐weighted magnetic resonance imaging (MRI) is commonly used for anatomical visualization in the pelvis area, such as the prostate, with high soft‐tissue contrast. MRI can also provide functional information such as diffusion‐weighted imaging (DWI) which depicts the molecular diffusion processes in biological tissues. The combination of anatomical and functional imaging techniques is widely used in oncology, e.g., for prostate cancer diagnosis and staging. However, acquisition‐specific distortions as well as physiological motion lead to misalignments between T2 and DWI and consequently to a reduced diagnostic value. Image registration algorithms are commonly employed to correct for such misalignment.

Methods:

The authors compare the performance of five state‐of‐the‐art nonrigid image registration techniques for accurate image fusion of DWI with T2.

Results:

Image data of 20 prostate patients with cancerous lesions or cysts were acquired. All registration algorithms were validated using intensity‐based as well as landmark‐based techniques.

Conclusions:

The authors’ results show that the “fast elastic image registration” provides most accurate results with a target registration error of 1.07 ± 0.41 mm at minimum execution times of 11 ± 1 s.
Experimental hybrid entanglement between quantum and classical states of light
Authors: Costanzo Luca S. , Zavatta Alessandro , Grandi Samuele , Bellini Marco , Jeong Hyunseok , Kang Minsu , Lee Seung-Woo , Ralph Timothy C.
Published: December 2014

The realization of hybrid entanglement between a microscopic (quantum) and a macroscopic (classical) system, in analogy to the situation of the famous Schrödinger's cat paradox, is an important milestone, both from the fundamental perspective and for possible applications in the processing of quantum information. The most straightforward optical implementation of this condition is that of the entanglement between a single-photon and a coherent state. In this work, we describe the first step towards the generation of this type of hybrid entanglement from the experimental perspective.
Chimerism and Tolerance Induction in Kidney Transplantation
Authors: Traitanon Opas , Gallon Lorenzo
Published: December 2014

Chimerism is a state in which bone marrow hematopoietic stem cells from two genetically different animals coexist. To date, the approach has been used successfully to induce the state of immunologic tolerance in the animal models and is now being evaluated in clinical trials of both HLA-identical and HLA-mismatched living-donor kidney transplant recipients in some transplant centers with varying degrees of success. Although the results are promising, the current conditioning regimens are not optimal and longer-term follow up and multicenter studies are needed to ensure the efficacy and safety of the procedures.
Regulated Inositol‐Requiring Protein 1‐Dependent Decay as a Mechanism of Corin RNA and Protein Deficiency in Advanced Human Systolic Heart Failure
Authors: Lee Rebecca , Xu Bin , Rame J. Eduardo , Felkin Leanne E. , Barton Paul , Dries Daniel L.
Published: December 2014

Background

The compensatory actions of the endogenous natriuretic peptide system require adequate processing of natriuretic peptide pro‐hormones into biologically active, carboxyl‐terminal fragments. Natriuretic peptide pro‐peptide processing is accomplished by corin, a transmembrane serine protease expressed by cardiomyocytes.
Brain natriuretic peptide (BNP)
processing is inadequate in advanced heart failure and is independently associated with adverse outcomes; however, the molecular mechanisms causing impaired
BNP
processing are not understood. We hypothesized that the development of endoplasmic reticulum stress in cardiomyocytes in advanced heart failure triggers inositol‐requiring protein 1 (
IRE
1)‐dependent corin
mRNA
decay, which would favor a molecular substrate favoring impaired natriuretic peptide pro‐peptide processing.

Methods and Results

Two independent samples of hearts obtained from patients with advanced heart failure at transplant demonstrated that corin
RNA
was reduced as
Atrial natriuretic peptide (ANP)
/
BNP RNA
increased. Increases in spliced X‐box protein 1, a marker for
IRE
1‐endoribonuclease activity, were associated with decreased corin
RNA
. Moreover, ≈50% of the hearts demonstrated significant reductions in corin
RNA
and protein as compared to the nonfailing control sample. In vitro experiments demonstrated that induction of endoplasmic reticulum stress in cultured cardiomyocytes with thapsigargin activated
IRE
1's endoribonuclease activity and time‐dependent reductions in corin
mRNA
. In
HL
‐1 cells, overexpression of
IRE
1 activated
IRE
1 endoribonuclease activity and caused corin
mRNA
decay, whereas
IRE
1‐
RNA
interference with sh
RNA
attenuated corin
mRNA
decay after induction of endoplasmic reticulum stress with thapsigargin. Pre‐treatment of cells with Actinomycin D to inhibit transcription did not alter the magnitude or time course of thapsigargin‐induced corin
mRNA
decline, supporting the hypothesis that this was the result of
IRE
1‐mediated corin
mRNA
degradation.

Conclusions

These data support the hypothesis that endoplasmic reticulum stress‐mediated,
IRE
1‐dependent targeted corin
mRNA
decay is a mechanism leading to corin
mRNA
resulting in corresponding corin protein deficiency may contribute to the pathophysiology of impaired natriuretic peptide pro‐hormone processing in humans processing in humans with advanced systolic heart failure.
Two new species of ghost shrimp assigned to the genus Cheramus Spence Bate, 1888 (Crustacea: Decapoda: Axiidea: Callianassidae) from the Ryukyu Islands, Japan
Authors: KOMAI TOMOYUKI , MAENOSONO TADAFUMI , FUJITA YOSHIHISA
Published: December 2014

Two new species of the callianassid ghost shrimp are described and illustrated on the basis of specimens from the Ryukyu Islands, Japan. These are provisionally assigned to the genus Cheramus Spence Bate, 1888, and appear closest to Callianassa acutirostella Sakai, 1988, also provisionally transferred to Cheramus herewith. These three species can be differentiated by characters of the telson, third maxilliped, chelipeds and uropod. The taxonomic status of Cheramus is briefly discussed.
Revision of the Australian species of Gonatopus group 5 (Hymenoptera: Dryinidae), with description of a new species from the Society Islands, French Polynesia
Authors: Olmi Massimo , Marletta Alessandro , Guglielmino Adalgisa
Published: December 2014

Eleven Australian species of Gonatopus Ljungh, 1810 group 5 are revised. A new species is described from the Leeward Islands: G. perraulti Olmi, Marletta & Guglielmino, sp. nov. (French Polynesia: Society Islands). New combination is proposed for G. levis (Olmi, 1991), comb. nov. (from Dicondylus). A new key to the Australian species of Gonatopus group 5 is presented.
New species of Uropodina from Madagascar (Acari: Mesostigmata)
Authors: KONTSCHÁN JENŐ , STARÝ Josef
Published: December 2014

Seven new species and one new genus of Uropodina are described from Madagascar. The third Afrotropical species of Polyaspis is described (Polyapis (Polyaspis) madagascarensis sp. nov.), with a key to the Afrotropical species of the genus. The first species of Dinychus from the Afrotropical region is described, as Dinychus lepus sp. nov.. An unusual new species of Trichouropoda species is described as Trichouropoda madagascarica sp. nov.. A new genus (Malagana gen. nov.) is described, with type species Malagana rotunda sp. nov.. The genus Pulchellaobovella is recorded from the Afrotropical Region for the first time, on the basis of Pulchellaobovella madagascarica sp. nov., with nomenclatural notes on the genera Pulchellaobovella and Janetiella. Uroobovella graeca Kontschán, 2010 is moved into the genus Pulchellaobovella, as Pulchellaobovella graeca (Kontschán, 2010b) comb. nov. Two new species of Rotundabaloghia (Circobaloghia) are described, Rotundabaloghia (Circobaloghia) ermilovi sp. nov. and Rotundabaloghia (Circobaloghia) kaydani sp. nov.
Laetosphecia, a new genus of clearwing moths from south-eastern China, with a brief review of the Sesiini from China (Lepidoptera, Sesiidae)
Authors: KALLIES AXEL , ARITA YUTAKA , OWADA MAMORU , WANG MIN
Published: December 2014

In this study, a new genus of Sesiini, Laetosphecia Kallies & Arita gen. nov., is described. The type species, Laetosphecia variegata (Walker, 1865) comb. nov., and a new species, Laetosphecia brideliana Kallies & Arita spec. nov., occur in south-eastern China (Province of Guangdong and Hong Kong). The larvae of both species cause galls in small branches of Bridelia tomentosa Blume (Phyllanthaceae). Furthermore, Laetosphecia leucozona (Hampson, 1919) comb. nov. from north-eastern India is transferred to the new genus. Additionally, we briefly review the Sesiini fauna of Mainland China and present an updated checklist for this region. Trilochana caseariae Yang & Wang, 1989 syn. nov. is established as a junior synonym of Trilochana scolioides Moore, 1879. Lenyra ashtaroth (Westwood, 1848) and Sphecosesia rhodites Kallies & Arita, 2004 are reported from China for the first time.
Pentamyrmexini, a new tribe for Pentamyrmex spinosus, a remarkable new genus and species of Pentatomidae (Hemiptera: Heteroptera) from Thailand
Authors: RIDER DAVID A. , BRAILOVSKY HARRY
Published: December 2014

Pentamyrmex spinosus new genus, new species is described, and a new tribe is erected for this remarkable insect. This is the first report of ant mimicry in the Pentatomidae.