bluuebunny/crossref_metadata_2025 huggingface dataset:
ROBUST SOUND LOCALIZATION USING SMALL NUMBER OF MICROPHONES
Authors: GE SHUZHI SAM , LOH AI POH , GUAN FENG
Published: May 2005

In this paper, robust sound localization is proposed for systems with spatially distributed microphones fewer than 4, the minimum required criteria for 3D sound localization in the literature, in an effort to address the robustness issues of microphone failures. It is shown that, for three- and two-microphone systems, two and four samples of the Interaural Time Difference (ITD) measurements are required respectively. In a one-microphone system, five samples of the Interaural Intensity Difference (IID) measurement should be used instead. These investigations are important because if one microphone fails, the remaining system can still function to locate the sound source without significant impact on the localization system. In addition, our investigation also shows that a 3-microphone system can estimate the azimuth and elevation simultaneously, which usually requires 4 microphones in the literature. Simulation and experimental results are presented to illustrate the performance of a three-microphone system. Results show that the system can locate the sound source with satisfactory accuracy.
EFFICIENT MAGNETIC LOCALIZATION AND ORIENTATION TECHNIQUE FOR CAPSULE ENDOSCOPY
Authors: HU CHAO , MENG MAX Q.-H. , MANDAL MRINAL
Published: May 2005

To build a new wireless robotic capsule endoscope with external guidance for controllable and interactive GI tract examination, a sensing system is needed for tracking 3D location and 2D orientation of the capsule endoscope movement. An appropriate sensing method is to enclose a small permanent magnet in the capsule. The intensities of the magnetic field produced by the magnet in different spatial points can be measured by the magnetic sensors outside the patient's body. With the sensing data of magnetic sensor array, the 3D location and 2D orientation of the capsule can be calculated. Higher calculation accuracy can be obtained if more sensors and optimal algorithm are applied. In this paper, different nonlinear optimization algorithms were evaluated to solve the magnet's 5D parameters, e.g. Powell's, Downhill Simplex, DIRECT, Multilevel Coordinate Search, and Levenberg Marquardt method. We have found that Levenberg-Marquardt method provides satisfactory calculation accuracy and faster speed. Simulations were done for investigating the de-noise ability of this algorithm based on different sensor arrays. Also the real experiment shows that the results are satisfactory with high accuracy (average localization error is 5.6 mm).
DIGITAL IMAGE WATERMARKING CAPACITY ANALYSIS
Authors: ZHANG FAN , ZHANG HONGBIN
Published: May 2005

In watermarking schemes, image can be considered as a communication channel to transmit messages. This paper presents a new adaptive capacity analysis scheme for image watermarking, realizes a content adaptive watermarking algorithm invisibly embedding the strongest watermark, and discusses the watermarking capacity of blind watermarking and non-blind watermarking. This paper also analyzes the relation between watermarking capacity and watermarking detection bit error rate (BER), and derives the relation between capacity and the limit of BER. According to the result of research, watermarking detection BER mainly influenced by the watermarking average energy and watermarking capacity. The BER rises with the increase of watermarking capacity.
NEW METHOD OF NONLINEAR RECTIFICATION OF SENSOR SYSTEMS
Authors: CHEN JUNJIE , HUANG WEIYI
Published: May 2005

Genetic neural network model of solving the problem of nonlinearity rectification of sensor systems, is put forward in the light of the shortcomings of least square and other conventional methods. And in theory the model is emphatically expounded. Computer simulations are presented to demonstrate that approximation accuracy of the model is far higher than the conventional least square method and the model possesses stronger robustness through adopting the methods in this paper. The research in the paper indicates that the model can also be used to realize nonlinearity rectification in other similar systems.
Ca2+/calmodulin-dependent protein kinase IV activates cysteine-rich protein 1 through adjacent CRE and CArG elements
Authors: Najwer Ida , Lilly Brenda
Published: May 2005

Smooth muscle-specific transcription is controlled by a multitude of transcriptional regulators that cooperate to drive expression in a temporospatial manner. Previous analysis of the cysteine-rich protein 1 ( CRP1/Csrp) gene revealed an intronic enhancer that is sufficient for expression in arterial smooth muscle cells and requires a serum response factor-binding CArG element for activity. The presence of a CArG box in smooth muscle regulatory regions is practically invariant; however, it stands to reason that additional elements contribute to the modulation of transcription in concert with the CArG. Because of the potential importance of other regulatory elements for expression of the CRP1 gene, we sought to identify additional motifs within the enhancer that are necessary for expression. In this effort, we identified a conserved cAMP response element (CRE) that, when mutated, diminishes the expression of the enhancer in cultured vascular smooth muscle cells. Using transfection and electrophoretic mobility shift assays, we have shown that the CRE binds the cAMP response element-binding protein (CREB) and is activated by Ca2+/calmodulin-dependent protein kinase IV (CaMKIV), but not by CaMKII. Furthermore, our data demonstrate that CaMKIV stimulates CRP1 expression not only through the CRE but also through the CArG box. These findings represent evidence of a functional CRE within a smooth muscle-specific gene and provide support for a mechanism in which CREB functions as a smooth muscle determinant through CaMKIV activation.
Fluid secretion and the Na+-K+-2Cl− cotransporter in mouse exorbital lacrimal gland
Authors: Walcott Benjamin , Birzgalis Aija , Moore Leon C. , Brink Peter R.
Published: May 2005

We have previously suggested that fluid flow in the mouse exorbital lacrimal gland is driven by the opening of apical Cl− and K+ channels. These ions move into the lumen of the gland and water follows by osmosis. In many tissues, the Na+-K+-2Cl− cotransporter (NKCC1) replaces the Cl− and K+ ions that move into the lumen. We hypothesize that mouse exorbital lacrimal glands would have NKCC1 cotransporters and that they would be important in fluid transport by this gland. We used immunocytochemistry to localize NKCC1-like immunoreactivity to the membranes of the acinar cells as well as to the basolateral membranes of the duct cells. We developed a method to measure tear flow and its composition from mouse glands in situ. Stimulation with the acetylcholine agonist carbachol produced a peak flow followed by a plateau. Ion concentration measurements of this stimulated fluid showed it was high in K+ and Cl−. Treatment of the gland with furosemide, a blocker of the NKCC1 cotransporter, reduced the plateau phase of fluid flow by ∼30%. Isolated cells exposed to a hypertonic shock shrank by ∼20% and then showed a regulatory volume increase (RVI). Both the RVI and swelling were blocked by treatment with furosemide. Cells isolated from these glands shrink by ∼10% in the presence of carbachol. Blocking NKCC1 with furosemide reduced the amount of shrinkage by ∼50%. These data suggest that NKCC1 plays an important role in fluid secretion by the exorbital gland of mice.
Shank2E binds NaPi cotransporter at the apical membrane of proximal tubule cells
Authors: McWilliams Ryan R. , Breusegem Sophia Y. , Brodsky Kelley F. , Kim Eunjoon , Levi Moshe , Doctor R. Brian
Published: May 2005

Proteins expressing postsynaptic density (PSD)-95/ Drosophila disk large (Dlg)/zonula occludens-1 (ZO-1) (PDZ) domains are commonly involved in moderating receptor, channel, and transporter activities at the plasma membrane in a variety of cell types. At the apical membrane of renal proximal tubules (PT), the type IIa NaPi cotransporter (NaPi-IIa) binds specific PDZ domain proteins. Shank2E is a spliceoform of a family of PDZ proteins that is concentrated at the apical domain of liver and pancreatic epithelial cell types and is expressed in kidney. In the present study, immunoblotting of enriched plasma membrane fractions and immunohistology found Shank2E concentrated at the brush border membrane of rat PT cells. Confocal localization of Flag-Shank2E and enhanced green fluorescent protein-NaPi-IIa in cotransfected OK cells showed these proteins colocalized in the apical microvilli of this PT cell model. Shank2E coimmunoprecipitated with NaPi-IIa from rat renal cortex tissue and HA-NaPi-IIa coprecipitated with Flag-Shank2E in cotransfected human embryonic kidney HEK cells. Domain analysis showed that the PDZ domain of Shank2E specifically bound NaPi-IIa and truncation of the COOH-terminal TRL motif from NaPi-IIa abolished this binding, and Far Western blotting showed that the Shank2E- NaPi-IIa interaction occurred directly between the two proteins. NaPi-IIa activity is regulated by moderating its abundance in the apical membrane. High-Pi conditions induce NaPi-IIa internalization and degradation. In both rat kidney PT cells and OK cells, shifting to high-Pi conditions induced an acute internal redistribution of Shank2E and, in OK cells, a significant degree of degradation. In sum, Shank2E is concentrated in the apical domain of renal PT cells, specifically binds NaPi-IIa via PDZ interactions, and undergoes Pi-induced internalization.
Morphological and electrophysiological changes in mouse dorsal root ganglia after partial colonic obstruction
Authors: Huang Tian-Ying , Hanani Menachem
Published: May 2005

There is evidence that sensitization of neurons in dorsal root ganglia (DRG) may contribute to pain induced by intestinal injury. We hypothesized that obstruction-induced pain is related to changes in DRG neurons and satellite glial cells (SGCs). In this study, partial colonic obstruction was induced by ligation. The neurons projecting to the colon were traced by an injection of 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate into the colon wall. The electrophysiological properties of DRG neurons were determined using intracellular electrodes. Dye coupling was examined with an intracellular injection of Lucifer yellow (LY). Morphological changes in the colon and DRG were examined. Pain was assessed with von Frey hairs. Partial colonic obstruction caused the following changes. First, coupling between SGCs enveloping different neurons increased 18-fold when LY was injected into SGCs near neurons projecting to the colon. Second, neurons were not coupled to other neurons or SGCs. Third, the firing threshold of neurons projecting to the colon decreased by more than 40% ( P < 0.01), and the resting potential was more positive by 4–6 mV ( P < 0.05). Finally, the number of neurons displaying spontaneous spikes increased eightfold, and the number of neurons with subthreshold voltage oscillations increased over threefold. These changes are consistent with augmented neuronal excitability. The pain threshold to abdominal stimulation decreased by 70.2%. Inflammatory responses were found in the colon wall. We conclude that obstruction increased neuronal excitability, which is likely to be a major factor in the pain behavior observed. The augmented dye coupling between glial cells may contribute to the neuronal hyperexcitability.
Secretin activates vagal primary afferent neurons in the rat: evidence from electrophysiological and immunohistochemical studies
Authors: Li Ying , Wu Xiaoyin , Yao Harry , Owyang Chung
Published: May 2005

In this study, we evaluated the vagal afferent response to secretin at physiological concentrations and localized the site of secretin's action on vagal afferent pathways in the rat. The discharge of sensory neurons supplying the gastrointestinal tract was recorded from nodose ganglia. Of 91 neurons activated by electrical vagal stimulation, 19 neurons showed an increase in firing rate in response to intestinal perfusion of 5-HT (from 1.5 ± 0.2 to 25 ± 4 impulses/20 s) but no response to intestinal distension. A close intra-arterial injection of secretin (2.5 and 5.0 pmol) elicited responses in 15 of these 19 neurons (from 1.5 ± 0.2 impulses/20 s at basal to 21 ± 4 and 43 ± 5 impulses/20 s, respectively). Subdiaphragmatic vagotomy and perivagal application of capsaicin, but not supranodose vagotomy, completely abolished the secretin-elicited vagal nodose neuronal response. In a separate study, 9 tension receptor afferents among 91 neurons responded positively to intestinal distension but failed to respond to luminal 5-HT. These nine neurons also showed no response to administration of secretin. As expected, immunohistochemical studies showed that secretin administration significantly increased the number of Fos-positive neurons in vagal nodose ganglia. In conclusion, we demonstrated for the first time that vagal sensory neurons are activated by secretin at physiological concentrations. A subpopulation of secretin-sensitive vagal afferent fibers is located in the intestinal mucosa, many of which are responsive to luminal 5-HT.
Identification of a spontaneously active, Na+-permeable channel in guinea pig gallbladder smooth muscle
Authors: Petkov Georgi V. , Balemba Onesmo B. , Nelson Mark T. , Mawe Gary M.
Published: May 2005

The action potential in gallbladder smooth muscle (GBSM) is caused by Ca2+ entry through voltage-dependent Ca2+ channels (VDCC), which contributes to the GBSM contractions. Action potential generation in GBSM is critically dependent on the resting membrane potential (about −50 mV), which is ∼35 mV more positive of the K+ equilibrium potential. We hypothesized that a tonic, depolarizing conductance is present in GBSM and contributes to the regulation of the resting membrane potential and action potential frequency. GBSM cells were isolated from guinea pig gallbladders, and the whole cell patch-camp technique was used to record membrane currents. After eliminating the contribution of VDCC and K+ channels, we identified a novel spontaneously active cation conductance ( Icat) in GBSM. This Icat was mediated predominantly by influx of Na+. Na+ substitution with N-methyl-d-glucamine (NMDG), a large relatively impermeant cation, caused a negative shift in the reversal potential of the ramp current and reduced the amplitude of the inward current at −50 mV by 65%. Membrane potential recordings with intracellular microelectrodes or in current-clamp mode of the patch-clamp technique indicated that the inhibition of Icat conductance by NMDG is associated with membrane hyperpolarization and inhibition of action potentials. Extracellular Ca2+, Mg2+, and Gd3+ attenuated the Icat in GBSM. Muscarinic stimulation did not activate the Icat. Our results indicate that, in GBSM, an Na+-permeable channel contributes to the maintenance of the resting membrane potential and action potential generation and therefore plays a critical role in the regulation of GBSM excitability and contractility.
Secretin differentially sensitizes rat pancreatic acini to the effects of supramaximal stimulation with caerulein
Authors: Perides G. , Sharma A. , Gopal A. , Tao X. , Dwyer K. , Ligon B. , Steer M. L.
Published: May 2005

Supramaximal stimulation of the rat pancreas with CCK, or its analog caerulein, triggers acute pancreatitis and a number of pancreatitis-associated acinar cell changes including intracellular activation of digestive enzyme zymogens and acinar cell injury. It is generally believed that some of these various acinar cell responses to supramaximal secretagogue stimulation are interrelated and interdependent. In a recent report, Lu et al. ( 8 ) showed that secretin, by causing generation of cAMP and activation of PKA, sensitizes acinar cells to secretagogue-induced zymogen activation, and, as a result, submaximally stimulating concentrations of caerulein can, in the presence of secretin, trigger intracellular zymogen activation. We found that secretin also sensitizes acinar cells to secretagogue-induced cell injury and to subapical F-actin redistribution but that it did not alter the caerulein concentration dependence of other pancreatitis-associated changes such as the induction of a peak plateau intracellular [Ca2+] rise, inhibition of secretion, activation of ERK1/2, and activation of NF-κB. The finding that secretin sensitizes acinar cells to both intracellular zymogen activation and cell injury is consistent with the concept that these two early events in pancreatitis are closely interrelated and, possibly, interdependent. On the other hand, the finding that, in the presence of secretin, caerulein can trigger subapical F-actin redistribution without inhibiting secretion challenges the concept that disruption of the subapical F-actin web is causally related to high-dose secretagogue-induced inhibition of secretion in pancreatic acinar cells.
Viscerosensory-cardiovascular reflexes: altered baroreflex sensitivity in irritable bowel syndrome
Authors: van der Veek Patrick P. J. , Swenne Cees A. , Vooren Hedde van de , Schoneveld Annelies L. , Maestri Roberto , Masclee Ad A. M.
Published: May 2005

Animal studies have demonstrated that visceral afferent stimulation alters autonomic cardiovascular reflexes. This mechanism might play an important role in the pathophysiology of conditions associated with visceral hypersensitivity, such as irritable bowel syndrome (IBS). As such, studies in humans are lacking, we measured viscerosensory-cardiovascular reflex interactions in IBS patients and healthy controls. Systolic blood pressure (SBP), heart rate (HR), and arterial baroreflex sensitivity (BRS) were studied in 87 IBS patients and 36 healthy controls under baseline conditions and during mild (15 mmHg) and intense (35 mmHg) visceral stimulation by rectal balloon distension. BRS was computed from continuous ECG and arterial blood pressure signals (Finapres-method) during 5-min periods of 15-min metronome respiration. Baseline SBP and HR were not different between patients and controls. In both groups, SBP increased similarly during rectal stimulation, whereas HR decreased during mild and increased intense stimulation. BRS was significantly higher in patients compared with controls at baseline (7.9 ± 5.4 vs. 5.7 ± 3.7 ms/mmHg, P = 0.03) and increased significantly in both groups during mild stimulation. This increase persisted in controls during intense stimulation, but BRS returned to baseline in patients. BRS was not significantly different between groups during rectal distension. This study demonstrates the presence of a viscerosensory-cardiovascular reflex in healthy individuals and in IBS patients. The increased BRS in IBS patients at baseline may either be a training-effect (frequent challenging of the reflex) or reflects altered viscerosensory processing at the nucleus tractus solitarii.
Distinctive features of dietary phosphate supply
Authors: Landsman Anna , Lichtstein David , Ilani Asher
Published: May 2005

Dietary phosphate has profound effects on growth and renal handling of the compound. On the basis of changes in growth rate and food intake, after alterations in phosphate load, our laboratory previously suggested that these effects are mediated by intestinal signals (Landsman A, Lichtstein D, Bacaner M, and Ilani A. Br J Nutr 86: 217–223, 2001). The aim of this study was to further evaluate the role of dietary phosphate on food intake and appetite and specific organ growth, and to test for the presence of a serum factor that may affect renal phosphate handling in phosphate-resupplied rats. The experimental design was based on a comparison between groups of rats receiving identical low-phosphate diets but drinking water containing either phosphate or chloride. We show that 1) changes in food intake after alterations in phosphate load occurred in parallel with variations in digestive system distention, suggesting that dietary phosphate has also a direct effect on appetite; 2) dietary phosphate-dependent growth has a specific effect on the growth of liver and epididymal fat; and 3) serum of rats supplied with phosphate contains a factor that inhibits sodium-dependent phosphate transport in a model of renal proximal tubule cells. Collectively, these observations are in accord with the hypothesis that factor(s) emanating from the digestive system in response to dietary phosphate load may be involved in growth, appetite and renal handling of phosphate.
Acute dopamine/norepinephrine reuptake inhibition increases brain and core temperature in rats
Authors: Hasegawa Hiroshi , Meeusen Romain , Sarre Sophie , Diltoer Marc , Piacentini Maria Francesca , Michotte Yvette
Published: May 2005

The purpose of the present study was to examine the effects of an acute dose of the dual dopamine (DA) and norepinephrine (NE) reuptake inhibitor bupropion (Bup) on brain (Tbrain), body core (Tcore), and tail skin (Ttail) temperature in freely moving rats and to simultaneously monitor the extracellular neurotransmitter concentrations in the preoptic area and anterior hypothalamus (PO/AH). A microdialysis probe was inserted in the PO/AH, and samples for NE, DA, and serotonin (5-HT) were collected every 20 min before and after the injection of 17 mg/kg of Bup, for a total sampling time of 180 min. Tcore was monitored using a biotelemetry system. Tbrain and Ttail, an index of heat loss response, were also measured. Both NE and DA levels in the PO/AH significantly increased after Bup injection compared with the baseline levels, reaching ∼450 and 230%, respectively, 40 min after injection. There was no effect on 5-HT release. The neurotransmitter changes were accompanied by a significant decrease in Ttail and an increase in both Tbrain and Tcore compared with the baseline levels. The present results demonstrate that inhibition of NE and DA reuptake suppresses heat loss mechanisms and elevates Tbrain and Tcore in freely moving rats.
Human growth hormone responses to repeated bouts of sprint exercise with different recovery periods between bouts
Authors: Stokes Keith , Nevill Mary , Frystyk Jan , Lakomy Henryk , Hall George
Published: May 2005

This study examined the growth hormone (GH) response to repeated bouts of sprint cycling. Eight healthy men completed three trials consisting of two 30-s sprints on a cycle ergometer separated by either 60 min ( Trial A) or 240 min ( Trial B) of recovery and a single 30-s sprint carried out the day after Trial B ( Trial C). Trials A and B were separated by at least 7 days. Blood samples were obtained at rest and during recovery from each sprint. In Trial A, GH was elevated immediately before sprint 2, and there was no further increase in GH following the second sprint [area under the curve: 460 (SD 348) vs. 226 min·μg−1·l−1 (SD 182), P = 0.05]. Free insulin-like growth factor I tended to be lower immediately before sprint 2 than sprint 1 ( P = 0.06). Serum free fatty acids were not different immediately before each of the sprints. In Trial B, there was a trend for a smaller GH response to the second sprint [GH area under the curve: 512 (SD 396) vs. 242 min·μg−1·l−1 (SD 190), P = 0.09]. Free insulin-like growth factor I tended to be lower ( P = 0.06), and serum free fatty acids were higher ( P = 0.01) immediately before sprint 2 than sprint 1. There was no difference in the GH response to sprinting on consecutive days ( Trials B and C). In conclusion, repeated bouts of sprint cycling on the same day result in an attenuation or even ablation of the exercise-induced increase in GH, depending on the recovery interval between sprints.
Delayed Inhibition in Cortical Receptive Fields and the Discrimination of Complex Stimuli
Authors: Narayan Rajiv , Ergün Ayla , Sen Kamal
Published: May 2005

Although auditory cortex is thought to play an important role in processing complex natural sounds such as speech and animal vocalizations, the specific functional roles of cortical receptive fields (RFs) remain unclear. Here, we study the relationship between a behaviorally important function: the discrimination of natural sounds and the structure of cortical RFs. We examine this problem in the model system of songbirds, using a computational approach. First, we constructed model neurons based on the spectral temporal RF (STRF), a widely used description of auditory cortical RFs. We focused on delayed inhibitory STRFs, a class of STRFs experimentally observed in primary auditory cortex (ACx) and its analog in songbirds (field L), which consist of an excitatory subregion and a delayed inhibitory subregion cotuned to a characteristic frequency. We quantified the discrimination of birdsongs by model neurons, examining both the dynamics and temporal resolution of discrimination, using a recently proposed spike distance metric (SDM). We found that single model neurons with delayed inhibitory STRFs can discriminate accurately between songs. Discrimination improves dramatically when the temporal structure of the neural response at fine timescales is considered. When we compared discrimination by model neurons with and without the inhibitory subregion, we found that the presence of the inhibitory subregion can improve discrimination. Finally, we modeled a cortical microcircuit with delayed synaptic inhibition, a candidate mechanism underlying delayed inhibitory STRFs, and showed that blocking inhibition in this model circuit degrades discrimination.
Visual Experience Is Necessary for Maintenance But Not Development of Receptive Fields in Superior Colliculus
Authors: Carrasco M. M. , Razak K. A. , Pallas S. L.
Published: May 2005

Sensory deprivation is thought to have an adverse effect on visual development and to prolong the critical period for plasticity. Once the animal reaches adulthood, however, synaptic connectivity is understood to be largely stable. We reported previously that N-methyl-d-aspartate (NMDA) receptor blockade in the superior colliculus of the Syrian hamster prevents refinement of receptive fields (RFs) in normal or compressed retinotopic projections, resulting in target neurons with enlarged RFs but normal stimulus tuning. Here we asked whether visually driven activity is necessary for refinement or maintenance of retinotopic maps or if spontaneous activity is sufficient. Animals were deprived of light either in adulthood only or from birth until the time of recording. We found that dark rearing from birth to 2 mo of age had no effect on the timing and extent of RF refinement as assessed with single unit extracellular recordings. Visual deprivation in adulthood also had no effect. Continuous dark rearing from birth into adulthood, however, resulted in a progressive loss of refinement, resulting in enlarged, asymmetric receptive fields and altered surround suppression in adulthood. Thus unlike in visual cortex, early visually driven activity is not necessary for refinement of receptive fields during development, but is required to maintain refined visual projections in adulthood. Because the map can refine normally in the dark, these results argue against a deprivation-induced delay in critical period closure, and suggest instead that early visual deprivation leaves target neurons more vulnerable to deprivation that continues after refinement.
Intracellular Analysis of Reflex Pathways Underlying the Stumbling Corrective Reaction During Fictive Locomotion in the Cat
Authors: Quevedo Jorge , Stecina Katinka , McCrea David A.
Published: May 2005

In cat and humans, contact between an obstacle and the dorsum of the foot evokes the stumbling corrective reaction (reflex) that lifts the foot to avoid falling. This reflex can also be evoked by short trains of stimuli to the cutaneous superficial peroneal (SP) nerve in decerebrate cats during the flexion phase of fictive locomotion. Here we examine intracellular events in hindlimb motoneurons accompanying stumbling correction. SP stimulation delivered during the flexion phase excites knee flexor motoneurons at short latency [minimum excitatory postsynaptic potential (EPSP) latency 1.8 ms; mean 2.7 ms]. Although a similar short latency excitation occurs in ankle extensors (mean latency, 2.8 ms), recruitment is delayed until successive shocks in the stimulus train overcome the locomotor-related hyperpolarization of ankle extensors. In ankle flexor motoneurons, SP stimulation evokes an inhibition (mean latency, 2.7 ms) that briefly reduces or stops their firing during the flexion phase. There is a phase-dependent modulation of SP-evoked EPSP amplitude as well as latency during locomotion. However, the more obvious change in SP reflex pathways with the onset of fictive locomotion is the reduced inhibition of ankle extensor motoneurons and the increased inhibition of ankle flexors. These results show that the characteristic pattern of hindlimb motoneuron activation during SP nerve–evoked stumbling correction results from 1) di- and trisynaptic excitation of knee flexor and ankle extensor motoneurons; 2) increased inhibitory postsynaptic potentials in ankle flexors and a suppression of inhibition in extensors, 3) sculpting of the short-latency SP postsynaptic effects by motoneuron membrane potential, and 4) longer latency excitatory effects that are likely evoked by lumbar interneurons involved in the generation of fictive locomotion.
Spontaneous Oscillatory Activity of Starburst Amacrine Cells in the Mouse Retina
Authors: Petit-Jacques Jerome , Völgyi Béla , Rudy Bernardo , Bloomfield Stewart
Published: May 2005

Using patch-clamp techniques, we investigated the characteristics of the spontaneous oscillatory activity displayed by starburst amacrine cells in the mouse retina. At a holding potential of –70 mV, oscillations appeared as spontaneous, rhythmic inward currents with a frequency of ∼3.5 Hz and an average maximal amplitude of ∼120 pA. Application of TEA, a potassium channel blocker, increased the amplitude of oscillatory currents by >70% but reduced their frequency by ∼17%. The TEA effects did not appear to result from direct actions on starburst cells, but rather a modulation of their synaptic inputs. Oscillatory currents were inhibited by 6-cyano-7-nitroquinoxalene-2,3-dione (CNQX), an antagonist of AMPA/kainate receptors, indicating that they were dependent on a periodic glutamatergic input likely from presynaptic bipolar cells. The oscillations were also inhibited by the calcium channel blockers cadmium and nifedipine, suggesting that the glutamate release was calcium dependent. Application of AP4, an agonist of mGluR6 receptors on on-center bipolar cells, blocked the oscillatory currents in starburst cells. However, application of TEA overcame the AP4 blockade, suggesting that the periodic glutamate release from bipolar cells is intrinsic to the inner plexiform layer in that, under experimental conditions, it can occur independent of photoreceptor input. The GABA receptor antagonists picrotoxin and bicuculline enhanced the amplitude of oscillations in starburst cells prestimulated with TEA. Our results suggest that this enhancement was due to a reduction of a GABAergic feedback inhibition from amacrine cells to bipolar cells and the resultant increased glutamate release. Finally, we found that some ganglion cells and other types of amacrine cell also displayed rhythmic activity, suggesting that oscillatory behavior is expressed by a number of inner retinal neurons.
Inhibition of Olfactory Receptor Neuron Input to Olfactory Bulb Glomeruli Mediated by Suppression of Presynaptic Calcium Influx
Authors: Wachowiak Matt , McGann John P. , Heyward Philip M. , Shao Zuoyi , Puche Adam C. , Shipley Michael T.
Published: May 2005

We investigated the cellular mechanism underlying presynaptic regulation of olfactory receptor neuron (ORN) input to the mouse olfactory bulb using optical-imaging techniques that selectively report activity in the ORN presynaptic terminal. First, we loaded ORNs with calcium-sensitive dye and imaged stimulus-evoked calcium influx in a slice preparation. Single olfactory nerve shocks evoked rapid fluorescence increases that were largely blocked by the N-type calcium channel blocker ω-conotoxin GVIA. Paired shocks revealed a long-lasting suppression of calcium influx with ∼40% suppression at 400-ms interstimulus intervals and a recovery time constant of ∼450 ms. Blocking activation of postsynaptic olfactory bulb neurons with APV/CNQX reduced this suppression. The GABABreceptor agonist baclofen inhibited calcium influx, whereas GABABantagonists reduced paired-pulse suppression without affecting the response to the conditioning pulse. We also imaged transmitter release directly using a mouse line that expresses synaptopHluorin selectively in ORNs. We found that the relationship between calcium influx and transmitter release was superlinear and that paired-pulse suppression of transmitter release was reduced, but not eliminated, by APV/CNQX and GABABantagonists. These results demonstrate that primary olfactory input to the CNS can be presynaptically regulated by GABAergic interneurons and show that one major intracellular pathway for this regulation is via the suppression of calcium influx through N-type calcium channels in the presynaptic terminal. This mechanism is unique among primary sensory afferents.
Saccade–Vergence Interactions in Macaques. I. Test of the Omnipause Multiply Model
Authors: Busettini C. , Mays L. E.
Published: May 2005

Horizontal vergence eye movements are movements in opposite directions used to change fixation between far and near targets. The occurrence of a saccade during vergence causes vergence velocity to be transiently enhanced. The goal of this study was to test in the monkey the previously described Multiply Model (Zee et al. 1992) that holds that, in humans, the speeding of vergence during a saccade may be the result of the disinhibition of a subgroup of vergence-related neurons by the saccadic omnipause neurons (OPNs). In agreement with the Multiply Model: 1) the onset of the enhancement was closely related to saccadic onset, and thus linked to the onset of the OPN pause; 2) the magnitude of the vergence velocity enhancement was strongly dependent on saccade–vergence timing. Contrary to the Multiply Model: 1) the peak of the vergence velocity enhancement was dependent on saccadic peak velocity; 2) the dependency on saccadic peak velocity was not the indirect result of a dependency on saccadic duration and therefore on the duration of the OPN pause; 3) the decline of the vergence enhancement, identified by the time of the peak of the enhancement velocity, occurred too early to be linked to the end of the OPN pause; 4) vergence enhancement had a saccadic-like peak-velocity/size main sequence. Overall, the evidence is incompatible with the OPN Multiply hypothesis of vergence enhancement. Alternative models are described in an accompanying paper.
Saccade–Vergence Interactions in Macaques. II. Vergence Enhancement as the Product of a Local Feedback Vergence Motor Error and a Weighted Saccadic Burst
Authors: Busettini C. , Mays L. E.
Published: May 2005

In the accompanying paper we reported that intrasaccadic vergence enhancement during combined saccade–vergence eye movements reflects saccadic dynamics, which implies the involvement of saccadic burst signals. This involvement was not predicted by the Multiply Model of Zee et al. We propose a model wherein vergence enhancement is the result of a multiplicative interaction between a weighted saccadic burst signal and a nonvisual short-latency estimate of the vergence motor error at the time of the saccade. The enhancement of vergence velocity by saccades causes the vergence goal to be approached more rapidly than if no saccade had occurred. The adjustment of the postsaccadic vergence velocity to this faster reduction in vergence motor error occurred with a time course too fast for visual feedback. This implies the presence of an internal estimate of the progress of the movement and indicates that vergence responses are under the control of a local feedback mechanism. It also implies that the vergence enhancement signal is included in the vergence feedback loop and is an integral part of the vergence velocity command. Our multiplicative model is able to predict the peak velocity of the vergence enhancement as a function of cyclopean saccadic dynamics, smooth vergence dynamics, and saccade–vergence timing with remarkable precision. It performed equally well for both horizontal and vertical saccades with very similar parameters, suggesting a common mechanism for all saccadic directions. A saccade–vergence additive model is also presented, although it would require external switching elements. Possible neural implementations are discussed.
Genetic Variation at the Human α
2B
-Adrenergic Receptor Locus
Authors: Etzel Jason P. , Rana Brinda K. , Wen Gen , Parmer Robert J. , Schork Nicholas J. , O’Connor Daniel T. , Insel Paul A.
Published: May 2005

Exaggerated response to α
2
-adrenergic receptor (α
2
-AR) blockade by yohimbine in normotensive subjects is an intermediate phenotype that predicts increased risk for development of hypertension. Here, we assessed the 3 α
2
-AR loci (α
2A,
α
2B,
α
2C
) as candidate genes for their influence on baseline and yohimbine-mediated increase in mean arterial pressure. Because initial results with 173 individuals implicated a possible association of yohimbine response with genetic variation at a site in the α
2B
-AR gene, but not at sites in the other 2 α
2
-AR, we sequenced the α
2B
-AR gene (4.4 kb, including 1.2 kb upstream and 1.9 kb distal to the coding sequence) in those subjects and an additional 81 individuals to search for other α
2B
-AR variants. We identified 25 polymorphisms, of which 14 are previously unreported, and 2 major haplotypes that differ by the presence/absence of a 9-bp in-frame deletion that encodes Glu
301
to Glu
303
. Frequency differences in haplotypes were observed between blacks and whites but did not predict response to yohimbine. Genotyping of 2 additional white cohorts, including 1269 individuals with extremes in blood pressure selected from >50 000 subjects, also failed to reveal an association of the 2 major α
2B
-AR haplotypes with differences in blood pressure. Thus, despite considerable polymorphism in α
2
-AR genes, such variation is not a major determinant of variability in yohimbine response and by inference, in susceptibility to essential hypertension.
Diabetes Educators
Authors: Barlow Susan , Crean John , Heizler Alissa , Mulcahy Kathy , Springer Jane
Published: May 2005

A survey evaluating the professional characteristics and practice patterns of diabetes educators was distributed across the United States. The specific survey aims were to assess whether (1) there continues to be a growing trend among US health professionals who consider themselves diabetes educators to obtain certification as certified diabetes educators (CDEs), (2) duties/services associated with diabetes self-management training (DSMT) and medical/medication management differ between diabetes educators who are CDEs versus those who are non-CDEs, and (3) educator practice patterns differ across the major geographic regions of the United States. Of the 507 diabetes educators completing the survey, 83% identified themselves as CDEs. Diabetes educators responding to similar surveys done in 1992 and 1999, 51% and 63%, respectively, identified themselves as CDEs. In this survey, a similar percentage of CDEs and non-CDEs employed DSMT practices of relatively low complexity (eg, general diabetes education) whereas a significantly higher percentage (P< .001) of CDEs employed DSMT practices of relatively high complexity (eg, insulin pump training). Significantly (P < .001) more CDEs provided medical/medication management services compared to non-CDEs. Finally, the practice patterns among CDEs were minimally influenced by region of the country. These results suggest that (1) the trend toward increased certification among diabetes educators has continued, (2) certification is associated with a greater likelihood of delivering complex DSMT services and medical/medication management, and (3) this pattern is consistent across the nation as a whole.
The Frequency and Behavioral Outcomes of Goal Choices in the Self-management of Diabetes
Authors: Estabrooks Paul A. , Nelson Candace C. , Xu Stanley , King Diane , Bayliss Elizabeth A. , Gaglio Bridget , Nutting Paul A. , Glasgow Russell E.
Published: May 2005

Purpose

The purpose of this study was to determine the frequency and effectiveness of behavioral goal choices in the self-management of diabetes and to test goal-setting theory hypotheses that self-selection and behavioral specificity of goals are key to enhancing persistence.

Methods

Participants with type 2 diabetes in a randomized controlled trial (n = 422) completed baseline behavioral assessments using a clinic-based, interactive, self-management CD-ROM that allowed them to select a behavioral goal and receive mail and telephone support for the initial 6 months of the trial followed by additional behavioral assessments. Frequency of behavioral goal selection and 6-month behavioral data were collected.

Results

Approximately 49%, 27%, and 24% of the participants, respectively, set goals to increase physical activity (PA), reduce fat intake, or increase fruits and vegetables (F&V) consumed. At baseline, participants who selected PA, reduced fat consumption, or F&V were significantly, and respectively, less active, consumed more dietary fat, and ate fewer F&V regardless of demographic characteristics. Participants who selected a reduced-fat goal showed a significantly larger decrease than did those that selected PA or F&V goals. Participants who selected an F&V goal showed significant changes in F&V consumption. Participants who selected a PA goal demonstrated significant changes in days of moderate and vigorous physical activity.

Conclusions

When participants are provided with information on health behavior status and an option of behavioral goals for managing type 2 diabetes, they will select personally appropriate goals, resulting in significant behavioral changes over a 6-month period.
Cardiovascular Endurance and Heart Rate Variability in Adolescents With Type 1 or Type 2 Diabetes
Authors: Faulkner Melissa Spezia , Quinn Laurie , Rimmer James H. , Rich Barry H.
Published: May 2005

Background. Incidence rates of both type 1 and type 2 diabetes mellitus (DM) are increasing in youth and may eventually contribute to premature heart disease in early adulthood. This investigation explored the influence of type of diabetes, gender, body mass index (BMI), metabolic control (HbA1c), exercise beliefs and physical activity on cardiovascular endurance (CE), and heart rate variability (HRV). Differences in exercise beliefs, physical activity, HRV, and CE in youth with type 1 versus type 2 DM were determined. Methods. Adolescents with type 1 DM (n = 105) or with type 2DM (n = 27) completed the Exercise Belief Instrument and the Physical Activity Recall. Twenty-four HRV measures were obtained via Holter monitoring and analyzed using SpaceLabs Vision Premier™ software system. The McMaster cycle test was used to measure CE (V02peak). Results. Regardless of the type of DM, females and those with higher BMI, poorer metabolic control, and lower amounts of physical activity tended to have lower levels of CE. Exercise beliefs consistently predicted both frequency and time domain HRV measures. Measures of exercise beliefs, self-reported physical activity, CE (V02peak), and HRV were significantly lower in adolescents with type 2 DM in comparison to those with type 1 DM. Conclusions and Recommendations. Early findings of poor physical fitness, lower HRV, fewer positive beliefs about exercise, and less active lifestyles highlight the importance of developing culturally sensitive interventions for assisting youth to make lifelong changes in their physical activity routines. Females, those with poorer metabolic control, and minority youth with type 2 DM may be particularly vulnerable to later cardiovascular disease.
The Roles of Marriage and Anger Dysregulation in Biobehavioral Stress Responses
Authors: Carrère Sybil , Yoshimoto Dan , Mittmann Angela , Woodin Erica M. , Tabares Amber , Ullman Jodie , Swanson Catherine , Hawkins Melissa
Published: May 2005

Physiological and behavioral correlates of anger dysregulation in adults were evaluated in the context of marital stress. Fifty-four married couples participated in a series of laboratory procedures that included electrocardiogram measures during a 15-min marital conflict interaction and an interview assessing their inability to regulate anger (anger dysregulation). Results from the multivariate regression analyses indicated that the nature of the couple’s relationship, rather than individual levels of anger dysregulation, predicted lower parasympathetic cardiac activity (indexed by high-frequency heart period variability) and shorter cardiac interbeat intervals. Anger dysregulation, rather than the dyadic relationship, was predictive of greater displays of angry behavior during the marital conflict interaction. The importance of contextual factors in stress processes, such as stress due to marriage, are discussed in light of research linking poor marital quality to greater health risks for women than for men.
The Role of Biobehavioral, Environmental, and Social Forces on Oral Health Disparities in Frail and Functionally Dependent Nursing Home Elders
Authors: Jablonski Rita A. , Munro Cindy L. , Grap Mary Jo , Elswick Ronald K.
Published: May 2005

The purpose of this article is to review the literature on and discuss how interactions between bio-behavioral aging, nursing home environments, and social forces shaping current health care policies have contributed to oral health disparities in frail and functionally dependent elders who reside in nursing homes. Emerging empirical evidence suggests links between poor oral health with dental plaque deposition and systemic disease, such as nursing home-acquired pneumonia. The majority of nursing home residents lack either the functional ability or the mental capacity to perform their own mouth care and therefore must rely on others to perform mouth care for them. Certified nursing assistants (CNAs), who provide the majority of care activities, were unsure how to provide care to residents who engaged in care-resistive behaviors. The nurses who supervise the CNAs have limited knowledge regarding the provision of mouth care in general, and they specifically lack knowledge regarding the provision of mouth care to elders exhibiting care-resistant behavior. Elders in nursing homes have limited options when paying for dental care; Medicare does not generally cover routine dental care. Medicaid coverage varies widely between individual states; even when coverage exists, low Medicaid reimbursements discourage dentists from accepting Medicaid patients. The strategies needed to reduce these oral health disparities are complicated but not unrealistic. Investigators willing to embrace this cause will have no shortage of opportunities to test methods to improve the delivery of oral care as well as to monitor and reassess these methods.
Biological Underpinnings of Health Alterations in Women With PTSD: A Sex Disparity
Authors: Gill Jessica M. , Szanton Sarah L. , Page Gayle G.
Published: May 2005

Women develop posttraumatic stress disorder (PTSD) at twice the rate of men, even though fewer women than men experience traumatic events over their lifetimes. Current studies of individuals with PTSD provide evidence of alterations in the neuroendocrine system that involve levels and activity of cortisol and DHEA and changes in immune function that predispose these individuals toward an innate (Th1) immune response. Yet few studies have addressed the possible role of these biologic alterations in women’s increased vulnerability to developing PTSD. In addition, current studies are limited in their ability to link biologic alterations to the observed fourfold increase in medical conditions in women with PTSD as compared to women without PTSD. And finally, few studies have addressed the biologic impact of co-occurring major depressive disorder (MDD) in individuals with PTSD. This critical review provides an update on neuroendocrine and immune perturbations associated with PTSD with and without cooccurring MDD to suggest links to health and possible mechanisms underlying the observed sex disparity in the development of PTSD.