bluuebunny/crossref_metadata_2025 huggingface dataset:
The OSIRIS instrument on the Odin spacecraft
Authors: Llewellyn E J , Lloyd N D , Degenstein D A , Gattinger R L , Petelina S V , Bourassa A E , Wiensz J T , Ivanov E V , McDade I C , Solheim B H , McConnell J C , Haley C S , von Savigny C , Sioris C E , McLinden C A , Griffioen E , Kaminski J , Evans W FJ , Puckrin E , Strong K , Wehrle V , Hum R H , Kendall D JW , Matsushita J , Murtagh D P , Brohede S , Stegman J , Witt G , Barnes G , Payne W F , Piché L , Smith K , Warshaw G , Deslauniers D -L , Marchand P , Richardson E H , King R A , Wevers I , McCreath W , Kyrölä E , Oikarinen L , Leppelmeier G W , Auvinen H , Mégie G , Hauchecorne A , Lefèvre F , de La Nöe J , Ricaud P , Frisk U , Sjoberg F , von Schéele F , Nordh L
Published: June 2004

The optical spectrograph and infrared imager system (OSIRIS) on board the Odin spacecraft is designed to retrieve altitude profiles of terrestrial atmospheric minor species by observing limb-radiance profiles. The grating optical spectrograph (OS) obtains spectra of scattered sunlight over the range 280800 nm with a spectral resolution of approximately 1 nm. The Odin spacecraft performs a repetitive vertical limb scan to sweep the OS 1 km vertical field of view over selected altitude ranges from approximately 10 to 100 km. The terrestrial absorption features that are superimposed on the scattered solar spectrum are monitored to derive the minor species altitude profiles. The spectrograph also detects the airglow, which can be used to study the mesosphere and lower thermosphere. The other part of OSIRIS is a three-channel infrared imager (IRI) that uses linear array detectors to image the vertical limb radiance over an altitude range of approximately 100 km. The IRI observes both scattered sunlight and the airglow emissions from the oxygen infrared atmospheric band at 1.27 µm and the OH (3-1) Meinel band at 1.53 µm. A tomographic inversion technique is used with a series of these vertical images to derive the two-dimensional distribution of the emissions within the orbit plane. PACS Nos.: 07.05.Pj, 07.60.Dq, 07.60.Rd, 07.87, 94.10.Dy, 94.10.Fa, 94.10.Gb, 94.10.Rk
The effect of radiation on free convective flow and mass transfer past a vertical isothermal cone surface with chemical reaction in the presence of a transverse magnetic field
Authors: Afify A A
Published: June 2004

The effects of radiation and chemical reactions, in the presence of a transverse magnetic field, on free convective flow and mass transfer of an optically dense viscous, incompressible, and electrically conducting fluid past a vertical isothermal cone surface are investigated. The nonlinear boundary-layer equations with the boundary conditions are transferred by a similarity transformation into a system of nonlinear ordinary differential equations with the appropriate boundary conditions. Furthermore, the similarity equations are solved numerically by using a fourth-order RungeKutta scheme with the shooting method. Numerical results for the skin-friction coefficient, the local Nusselt number, the local Sherwood number are given; as well, the velocity, temperature, and concentration profiles are presented for a Prandtl number of 0.7, the chemical-reaction parameter, the order of the reaction, the radiation parameter, the Schmidt number, the magnetic parameter, and the surface temperature parameter. PACS No.: 47.70.Fw
Canonical structure of the coupled Kortewegde Vries equations
Authors: Talukdar B , Ghosh S , Shamanna J
Published: June 2004

The inverse problem of variational calculus is solved for the coupled Kortewegde Vries equations resulting from a complex Lax pair. The system is found to be characterized by a second-order degenerate Lagrangian density having some common feature with the well-known MorseFeshbach Lagrangian. The Hamiltonian structure is examined using Dirac's theory of constraints. PACS Nos.: 47.20.Ky, 42.81.Dp
Chaos dynamique des particules relativistes accélérées dans un paquet d'ondes électrostatiques
Authors: Raouak A , Saifaoui D , Dezairi A
Published: June 2004

In this work, we study the diffusion of particle accelerated in an electromagnetic wave packet, through a numerical simulation of the relativistic standard map. We contribute to the field of stochastic diffusion of accelerated particles as a function of the stochastic parameter K, specially the transition between partial and global stochasticity, and we also compare our theoretical computation of the diffusion with numerical results.
Optically pumped lasing from organic microcavity
Authors: Liu X , Poitras D , Tao Y , Py C
Published: June 2004

An optically pumped organic laser has been fabricated using a DCM (4-dicyanmethylene-2-methyl-6-4H-pyran)-doped Alq (tris (8-hydroxyquinoline) aluminum) film as the gain medium sandwiched between a high-reflectance distributed Bragg reflector and a silver reflector. The stimulated emission properties were investigated by short-pulse laser pumping. The intensity ratio of the resonant peak at 604 nm to the DBR (distributed Bragg reflector)-modulated free space emission band changed greatly with increasing pump energy density. The dependence on the pump energy density of the output properties including the cavity mode output, the total output, and the ratio of the cavity output versus total output, indicates a clear threshold energy density of 400 ± 20 µJ/cm2. The effective gain coefficient at the threshold was about 250 ± 14 cm1. PACS No.: 42.55.Sa
Plasma and intracellular membrane inositol 1,4,5-trisphosphate receptors mediate the Ca2+ increase associated with the ATP-induced increase in ciliary beat frequency
Authors: Barrera Nelson P. , Morales Bernardo , Villalón Manuel
Published: June 2004

An increase in intracellular free Ca2+ concentration ([Ca2+]i) has been shown to be involved in the increase in ciliary beat frequency (CBF) in response to ATP; however, the signaling pathways associated with inositol 1,4,5-trisphosphate (IP3) receptor-dependent Ca2+ mobilization remain unresolved. Using radioimmunoassay techniques, we have demonstrated the appearance of two IP3 peaks occurring 10 and 60 s after ATP addition, which was strongly correlated with a release of intracellular Ca2+ from internal stores and an influx of extracellular Ca2+, respectively. In addition, ATP-dependent Ca2+ mobilization required protein kinase C (PKC) and Ca2+/calmodulin-dependent protein kinase II activation. We found an increase in PKC activity in response to ATP, with a peak at 60 s after ATP addition. Xestospongin C, an IP3 receptor blocker, significantly diminished both the ATP-induced increase in CBF and the initial transient [Ca2+]i component. ATP addition in the presence of xestospongin C or thapsigargin revealed that the Ca2+ influx is also dependent on IP3 receptor activation. Immunofluorescence and confocal microscopic studies showed the presence of IP3 receptor types 1 and 3 in cultured ciliated cells. Immunogold electron microscopy localized IP3 receptor type 3 to the nucleus, the endoplasmic reticulum, and, interestingly, the plasma membrane. In contrast, IP3 receptor type 1 was found exclusively in the nucleus and the endoplasmic reticulum. Our study demonstrates for the first time the presence of IP3 receptor type 3 in the plasma membrane in ciliated cells and leads us to postulate that the IP3 receptor can directly trigger Ca2+ influx in response to ATP.
Pulsatile LH release is diminished, whereas FSH secretion is normal, in hypocretin-deficient narcoleptic men
Authors: Kok S. W. , Roelfsema F. , Overeem S. , Lammers G. J. , Frölich M. , Meinders A. E. , Pijl H.
Published: June 2004

Hypocretin (orexin) peptides are involved in the regulation of energy balance and pituitary hormone release. Narcolepsy is a sleep disorder characterized by disruption of hypocretin neurotransmission. Pituitary LH secretion is diminished in hypocretin-deficient animal models, and intracerebroventricular administration of hypocretin-1 activates the hypothalamo-pituitary-gonadal axis in rats. We evaluated whether hypocretin deficiency affects gonadotropin release in humans. To this end, we deconvolved 24-h serum concentrations of LH and FSH in seven hypocretin-deficient narcoleptic males (N) and seven controls (C) matched for age, body mass index, and sex. Basal plasma concentrations of testosterone, estradiol, and sex hormone-binding globulin were similar in both groups. Mean 24-h LH concentration was significantly lower in narcolepsy patients [3.0 ± 0.4 (N) vs. 4.2 ± 0.3 (C) U/l, P = 0.01], which was primarily due to a reduction of pulsatile LH secretion [23.5 ± 1.6 (N) vs. 34.3 ± 4.9 (C) U·l−1·24 h−1, P = 0.02]. The orderliness of LH and FSH secretion, quantitated by the approximate entropy statistic, was greater in patients than in controls. In contrast, all other features of FSH release were similar in narcoleptic and control groups. Also, LH and FSH secretions in response to intravenous administration of 100 μg of GnRH were similar in patients and controls. These data indicate that endogenous hypocretins are involved in the regulation of the hypothalamo-pituitary-gonadal axis activity in humans. In particular, reduced LH release in the face of normal pituitary responsivity to GnRH stimulation in narcoleptic men suggests that hypocretins promote endogenous GnRH secretion.
Lipid and carbohydrate metabolism in mice with a targeted mutation in the IL-6 gene: absence of development of age-related obesity
Authors: Di Gregorio Gina B. , Hensley Lori , Lu Tong , Ranganathan Gouri , Kern Philip A.
Published: June 2004

Obesity-related insulin resistance may be caused by adipokines such as IL-6, which is known to be elevated with the insulin resistance syndrome. A previous study reported that IL-6 knockout mice (IL-6−/−) developed maturity onset obesity, with disturbed carbohydrate and lipid metabolism, and increased leptin levels. Because IL-6 is associated with insulin resistance, one might have expected IL-6−/−mice to be more insulin sensitive. We examined body weights of growing and older IL-6−/−mice and found them to be similar to wild-type (IL-6+/+) mice. Dual-energy X-ray absorptiometry analysis at 3 and 14 mo revealed no differences in body composition. There were no differences in fasting blood insulin and glucose or in triglycerides. To further characterize these mice, we fed 11-mo-old IL-6−/−and IL-6+/+mice a high- (HF)- or low-fat diet for 14 wk, followed by insulin (ITT) and glucose tolerance tests (GTT). An ITT showed insulin resistance in the HF animals but no difference due to genotype. In the GTT, IL-6−/−mice demonstrated elevated postinjection glucose levels by 60% compared with IL-6+/+but only in the HF group. Although IL-6−/−mice gained weight and white adipose tissue (WAT) with the HF diet, they gained less weight than the IL-6+/+mice. Total lipoprotein lipase activity in WAT, muscle, and postheparin plasma was unchanged in the IL-6−/−mice compared with IL-6+/+mice. There were no differences in plasma leptin or TNF-α due to genotype. Plasma adiponectin was ∼53% higher (71.7 ± 14.1 μg/ml) in IL-6−/−mice than in IL-6+/+mice but only in the HF group. Thus these data show that IL-6−/−mice do not demonstrate obesity, fasting hyperglycemia, or abnormal lipid metabolism, although HF IL-6−/−mice demonstrate elevated glucose after a GTT.
Reduced plasma FFA availability increases net triacylglycerol degradation, but not GPAT or HSL activity, in human skeletal muscle
Authors: Watt Matthew J. , Holmes Anna G. , Steinberg Gregory R. , Mesa Jose L. , Kemp Bruce E. , Febbraio Mark A.
Published: June 2004

Intramuscular triacylglycerols (IMTG) are proposed to be an important metabolic substrate for contracting muscle, although this remains controversial. To test the hypothesis that reduced plasma free fatty acid (FFA) availability would increase IMTG degradation during exercise, seven active men cycled for 180 min at 60% peak pulmonary O2 uptake either without (CON) or with (NA) prior ingestion of nicotinic acid to suppress adipose tissue lipolysis. Skeletal muscle and adipose tissue biopsy samples were obtained before and at 90 and 180 min of exercise. NA ingestion decreased ( P < 0.05) plasma FFA at rest and completely suppressed the exercise-induced increase in plasma FFA (180 min: CON, 1.42 ± 0.07; NA, 0.10 ± 0.01 mM). The decreased plasma FFA during NA was associated with decreased ( P < 0.05) adipose tissue hormone-sensitive lipase (HSL) activity (CON: 13.9 ± 2.5, NA: 9.1 ± 3.0 nmol·min−1·mg protein−1). NA ingestion resulted in decreased whole body fat oxidation and increased carbohydrate oxidation. Despite the decreased whole body fat oxidation, net IMTG degradation was greater in NA compared with CON (net change: CON, 2.3 ± 0.8; NA, 6.3 ± 1.2 mmol/kg dry mass). The increased IMTG degradation did not appear to be due to reduced fatty acid esterification, because glycerol 3-phosphate activity was not different between trials and was unaffected by exercise (rest: 0.21 ± 0.07; 180 min: 0.17 ± 0.04 nmol·min−1·mg protein−1). HSL activity was not increased from resting rates during exercise in either trial despite elevated plasma epinephrine, decreased plasma insulin, and increased ERK1/2 phosphorylation. AMP-activated protein kinase (AMPK)α1 activity was not affected by exercise or NA, whereas AMPKα2 activity was increased ( P < 0.05) from rest during exercise in NA and was greater ( P < 0.05) than in CON at 180 min. These data suggest that plasma FFA availability is an important mediator of net IMTG degradation, and in the absence of plasma FFA, IMTG degradation cannot maintain total fat oxidation. These changes in IMTG degradation appear to disassociate, however, from the activity of the key enzymes responsible for synthesis and degradation of this substrate.
Regional differences in L-type Ca2+channel expression in feline lower esophageal sphincter
Authors: Muinuddin Ahmad , Kang Youhou , Gaisano Herbert Y. , Diamant Nicholas E.
Published: June 2004

In humans and cats, muscle from the lower esophageal sphincter (LES) circular region exhibits greater spontaneous tone than LES sling muscle, whereas the sling muscle is much more responsive to cholinergic stimulation. Despite physiological and pharmacological evidence for the presence of L-type Ca2+channel current ( ICa,L) activity in LES circular muscle, the identity of this channel has not been demonstrated biochemically or electrophysiologically fingerprinted. Furthermore, there is no information on the channel's presence and role in the sling region of the LES. We hypothesized that regional differences in the expression of ICa,Lbetween LES circular and sling muscles, if present, could contribute to the functional asymmetry observed within the LES. ICa,Lexpression was compared between circular and sling regions of the LES by Western blot analysis. The patch-clamp technique was used to study ICa,L. Muscle strip studies assessed ICa,Lcontribution to contractile activity. We found both protein expression of ICa,Land ICa,Ldensity to be greater in LES circular muscle than sling muscle. ICa,Lvoltage- and time-dependent activation and inactivation curves were similar in cells from both regions. ICa,Lblockade with nifedipine inhibited spontaneous tone and ACh-induced contractions only in circular muscle but was able to abolish depolarization (KCl)-induced contractions in both sling and circular muscles. In contrast, La3+inhibited tone and ACh-induced contractions in muscles from both regions. Therefore, regional myogenic differences in ICa,Lexpression within the LES circular and sling muscle exist and provide one explanation for the differential contribution of sling and circular muscle to LES contractility.
Role of vasa vasorum in transendothelial solute transport in the coronary vessel wall: a study with cryostatic micro-CT
Authors: Gössl Mario , Beighley Patricia E. , Malyar Nasser M. , Ritman Erik L.
Published: June 2004

Using cryostatic microscopic computed tomography (micro-CT), we sought to determine the role of coronary vasa vasorum (VV) in transendothelial solute transport in arteries with normal and increased permeability due to high plasma cholesterol levels. In 6-mo-old pigs on a normal ( n = 23) and 2% high cholesterol (HC) diet ( n = 8), 2-cm segments of the proximal left anterior descending coronary arteries were removed in vivo after a selective injection of X-ray contrast solution. Harvesting of the specimens occurred at 0, 15, 25, 35, or 45 s after completion of the contrast injection. Specimens were snap frozen and scanned in our cryostatic micro-CT. The spatial distribution of contrast in the coronary artery wall was quantified using the CT images. Right coronary arteries were infused with Microfil to determine VV density (VV/mm2) and the cumulative lumen surface area (mm2/mm3). Transendothelial diffusion of contrast into the coronary vessel wall is a dynamic process starting at both the subintima and the adventitia. The subintimal opacification moves as a wave toward the adventitia, whereas the adventitial wave resolves. The coronary vessel wall in animals on a HC diet shows higher opacification than in normal coronary arteries without an increase of VV total luminal surface area. The loss of endothelial integrity in hypercholesterolemia significantly alters VV solute washin to, and washout from, the coronary artery wall.
Biventricular hypertrophy in dogs with chronic AV block: effects of cyclosporin A on morphology and electrophysiology
Authors: Schreiner Kirsten D. , Kelemen Kamilla , Zehelein Joerg , Becker Ruediger , Senges Julia C. , Bauer Alexander , Voss Frederik , Kraft Patrizia , Katus Hugo A. , Schoels Wolfgang
Published: June 2004

Chronic atrioventricular (AV) block (CAVB) and biventricular hypertrophy in dogs increase susceptibility to drug-induced polymorphic ventricular tachycardia (PVT). In various rodent models, cyclosporin A (CsA) prevented hypertrophy. A similar effect in the CAVB model would allow us to determine whether hypertrophy represents an epiphenomenon, the cause of electrophysiological changes, and/or the anatomic substrate for PVTs. Upon AV node ablation, 6 dogs were studied acutely (AAVB), 25 dogs were kept for 6 (6W) and 12 wk (12W), receiving no treatment [CTL-CAVB-6W ( n = 6) and CTL-CAVB-12W ( n = 7)] or a daily oral dose of 10–20 mg/kg CsA directly ( n = 6, CsA-CAVB-6W) or 6 wk after radio-frequency ablation ( n = 6, CsA-CAVB-12W). For the final study, dogs were anesthetized, and 60 needles were inserted into both ventricles and connected to a multiplexer mapping system. Local effective refractory periods (ERPs) were determined at 56 ± 22 randomly selected sites (extrastimulus technique, basic cycle length = 800 ms). Arrhythmias within 30 min after application of almokalant (0.34 μmol/kg iv) were registered. The hearts were then excised to obtain the heart weight-body weight index (HBWI). Compared with AAVB, CTL-CAVB-6W and CTL-CAVB-12W showed increased HBWI and ERP associated with PVT inducibility in none of six AAVB dogs, four of six CTL-CAVB-6W dogs, and one of seven CTL-CAVB-12W dogs. Compared with CTL-CAVB-6W and CTL-CAVB-12W, CsA-CAVB-6W and CsA-CAVB-12W partially prevented hypertrophy or led to a regression of hypertrophy without reducing ERP prolongation. Despite ERP prolongation, PVTs were no longer inducible with CsA treatment. Thus prolongation of refractoriness seems to provide the trigger, but hypertrophy provides the essential substrate for the induction of PVTs in this model.
Oxidant activity in skeletal muscle fibers is influenced by temperature, CO2level, and muscle-derived nitric oxide
Authors: Arbogast Sandrine , Reid Michael B.
Published: June 2004

Free radicals are produced continuously by skeletal muscle fibers. Extracellular release of reactive oxygen species (ROS) and nitric oxide (NO) derivatives has been demonstrated, but little is known about intracellular oxidant regulation. We used a fluorescent oxidant probe, 2′,7′-dichlorofluorescin (DCFH), to assess net oxidant activity in passive muscle fiber bundles isolated from mouse diaphragm and studied in vitro. We tested the following three hypotheses. 1) Net oxidant activity is decreased by muscle cooling. 2) CO2exposure depresses intracellular oxidant activity. 3) Muscle-derived ROS and NO both contribute to overall oxidant activity. Our results indicate that DCFH oxidation was diminished by cooling muscle fibers from 37°C to 23°C ( P < 0.001). The rate of DCFH oxidation correlated positively with CO2exposure (0–10%; P < 0.05) and negatively with concurrent changes in pH (7.0–8.5; P < 0.05). Separate exposures to anti-ROS enzymes (superoxide dismutase, 1 kU/ml; catalase, 1 kU/ml), a glutathione peroxidase mimetic (ebselen, 30 μM), NO synthase inhibitors ( Nω-nitro-l-arginine methyl ester, 1 mM; Nω-monomethyl-l-arginine, 1 mM), or an NO scavenger (hemoglobin, 1 μM) each inhibited DCFH oxidation ( P < 0.05). Oxidation was increased by hydrogen peroxide, 100 μM, an NO donor (NOC-22, 400 μM), or the substrate for NO synthase (l-arginine, 5 mM). We conclude that net oxidant activity in resting muscle fibers is 1) decreased at subphysiological temperatures, 2) increased by CO2exposure, and 3) influenced by muscle-derived ROS and NO derivatives to similar degrees.
Physiological characterization of human ovarian cancer cells in a rat model of intraperitoneal antineoplastic therapy
Authors: Flessner Michael F. , Choi Jaehwa , He Zhi , Credit Kimberly
Published: June 2004

Destruction of cancer cells by therapies directed against new molecular targets requires their effective delivery to the tumor. To study diffusion and convection of intraperitoneal (ip) therapy to ip tumors, we established a new athymic rat (RNU) model with ovarian tumor cells (SKOV3 and OVCAR3) implanted in the abdominal wall. The model simulates metastatic tumor and facilitates the measurement of physiological parameters that govern transport forces. CD31 immunohistochemistry revealed unique patterns of angiogenesis, with a tissue-averaged vascular volume of ∼0.01 ml/g for each tumor. The extracellular volume (SKOV3: 0.54 ± 0.11 ml/g, n = 5; OVCAR3: 0.61 ± 0.03, n = 5) was over twice that of the adjacent normal muscle (0.22 ± 0.06 ml/g, n = 5). Intravenous-injected antibody tumor clearance was two to three times that of muscle. Interstitial pressures were higher than normal tissue with a median of 10–15 mmHg. Quantitative autoradiography of frozen tissue slices from rats exposed to ip solutions containing [14C]mannitol or125I-immunoglobulin G (trastuzumab) was performed to determine transport of small and large molecules. With ip pressure of 0–6 mmHg, both mannitol and immunoglobulin G displayed steep concentration profiles close to the tumor surface with limited penetration deeper within the tumor tissue; antibody penetration was significantly affected by ip pressure. These results demonstrated effects of molecular size, ip pressure, the limited but highly permeable tumor vasculature, and the expanded interstitium on drug penetration from the peritoneal cavity. In conclusion, we have characterized physical and chemical parameters that determine transport of therapeutic agents in our unique tumor-bearing rat model.
Central inhibition of the aortic baroreceptors-heart rate reflex at the onset of spontaneous muscle contraction
Authors: Murata Jun , Matsukawa Kanji , Komine Hidehiko , Tsuchimochi Hirotsugu , Nakamoto Tomoko
Published: June 2004

Animals decerebrated at the precollicular-premammillary body level exhibit spontaneous locomotion without any artificial stimulation. Our laboratory reported that the cardiovascular and autonomic responses at the onset of spontaneous locomotor events are evoked by central command, generated from the caudal diencephalon and the brain stem (Matsukawa K, Murata J, and Wada T. Am J Physiol Heart Circ Physiol 275: H1115–H1121, 1998). In this study, we examined whether central command and/or a reflex resulting from muscle afferents modulates arterial baroreflex function using a decerebrate cat model. The baroreflex was evoked by stimulating the aortic depressor nerve (ADN) at the onset of spontaneous muscle contraction (to test the possible influence of central command) and during electrically evoked contraction or passive stretch (to test the possible influence of the muscle reflex). When the ADN was stimulated at rest, heart rate and arterial blood pressure decreased by 40 ± 2 beats/min and 11 ± 1 mmHg, respectively. The baroreflex bradycardia was attenuated to 55 ± 4% at the onset of spontaneous contraction. The attenuating effect on the baroreflex bradycardia was not observed at the onset and middle of electrically evoked contraction or passive stretch. The depressor response to ADN stimulation was identical among resting and any muscle interventions. The inhibition of the baroreflex bradycardia during spontaneous contraction was seen after β-adrenergic blockade but abolished by muscarinic blockade, suggesting that the bradycardia is mainly evoked through cardiac vagal outflow. We conclude that central command, produced within the caudal diencephalon and the brain stem, selectively inhibits the cardiac component, but not the vasomotor component, of the aortic baroreflex at the onset of spontaneous exercise.
Burn trauma alters calcium transporter protein expression in the heart
Authors: Ballard-Croft Cherry , Carlson Deborah , Maass David L. , Horton Jureta W.
Published: June 2004

We have shown previously that burn trauma produces significant cardiac dysfunction, which is first evident 8 h postburn and is maximal 24 h postburn. Because calcium handling by the cardiomyocyte is essential for cardiac function, one mechanism by which burn injury may cause cardiac abnormalities is via calcium dyshomeostasis. We hypothesized that major burn injury alters cardiomyocyte calcium handling through changes in calcium transporter expression. Sprague-Dawley rats were given either burn injury or no burn injury (controls). Cardiomyocyte intracellular calcium and sodium were quantified at various times postburn by fura 2-AM or sodium-binding benzofuran isophthalate fluorescent indicators, respectively. In addition, hearts freeze-clamped at various times postburn (2, 4, 8, and 24 h) were used for Western blot analysis using antibodies against the sarcoplasmic reticulum calcium-ATPase (SERCA), the L-type calcium-channel, the ryanodine receptor, the sodium/calcium exchanger, or the sodium-potassium-ATPase. Intracellular calcium levels were elevated significantly 8–24 h postburn, and intracellular sodium was increased significantly 4 through 24 h postburn. Expression of SERCA was significantly reduced 1–8 h postburn, whereas L-type calcium-channel expression was diminished 1 and 2 h postburn ( P < 0.05) but returned toward control levels 4 h postburn. Ryanodine receptor protein was significantly reduced at 1 and 2 h postburn, returning to baseline by 4 h postburn. Sodium/calcium exchanger expression was significantly elevated 2 h postburn but was significantly reduced 24 h postburn. An increase in sodium-potassium-ATPase expression occurred 2–24 h postburn. These data confirm that burn trauma alters calcium transporter expression, likely contributing to cardiomyocyte calcium loading and cardiac contractile dysfunction.
Neural coupling between upper and lower limbs during recumbent stepping
Authors: Huang Helen J. , Ferris Daniel P.
Published: June 2004

During gait rehabilitation, therapists or robotic devices often supply physical assistance to a patient's lower limbs to aid stepping. The expensive equipment and intensive manual labor required for these therapies limit their availability to patients. One alternative solution is to design devices where patients could use their upper limbs to provide physical assistance to their lower limbs (i.e., self-assistance). To explore potential neural effects of coupling upper and lower limbs, we investigated neuromuscular recruitment during self-driven and externally driven lower limb motion. Healthy subjects exercised on a recumbent stepper using different combinations of upper and lower limb exertions. The recumbent stepper mechanically coupled the upper and lower limbs, allowing users to drive the stepping motion with upper and/or lower limbs. We instructed subjects to step with 1) active upper and lower limbs at an easy resistance level (active arms and legs); 2) active upper limbs and relaxed lower limbs at easy, medium, and hard resistance levels (self-driven); and 3) relaxed upper and lower limbs while another person drove the stepping motion (externally driven). We recorded surface electromyography (EMG) from six lower limb muscles. Self-driven EMG amplitudes were always higher than externally driven EMG amplitudes ( P < 0.05). As resistance and upper limb exertion increased, self-driven EMG amplitudes also increased. EMG bursts during self-driven and active arms and legs stepping occurred at similar times. These results indicate that active upper limb movement increases neuromuscular activation of the lower limbs during cyclic stepping motions. Neurologically impaired humans that actively engage their upper limbs during gait rehabilitation may increase neuromuscular activation and enhance activity-dependent plasticity.
Laminar Specific Distribution of Lateral Excitatory Connections in the Rat Superior Colliculus
Authors: Saito Yasuhiko , Isa Tadashi
Published: June 2004

Premovement activities in neurons in the intermediate gray layer [stratum griseum intermediale (SGI)] of the mammalian superior colliculus (SC) are essential for initiation of orienting behaviors such as saccades. Our previous study demonstrated that burst activities are induced by synchronous activation of SGI neurons communicating within a local excitatory network, which depends on NMDA-receptor–dependent synaptic transmission and release from GABAA inhibition. Furthermore, dual whole cell recordings from adjacent neurons in SGI revealed that application of 10 μM bicuculline (Bic) and reduction of extracellular Mg2+ concentration (to 0.1 mM) induce spontaneous depolarization that is synchronous between neuron pairs, suggesting the recruitment of a large number of neurons communicating through intense excitatory connections. In the present study, we investigated the properties of synchronous depolarization and the fundamental structure of the lateral excitatory network that recruits a neuronal population in SC to synchronous activation, by analyzing the synchronicity of spontaneous depolarization induced in the presence of Bic plus low Mg2+. We found that 1) spontaneous depolarization exhibits bidirectional horizontal propagation among the SGI neuron pairs; 2) induction of spontaneous depolarization is not caused by activation of intrinsic voltage-dependent conductances; 3) neurons exposed to low Mg2+ alone exhibit spontaneous depolarization, although in this case the depolarization is less synchronous; and 4) neurons exposed to Bic alone exhibit synchronous depolarization, but less frequently than those exposed to both Bic and low Mg2+. Analysis of the synchronicity of spontaneous depolarization indicates that the distribution of lateral excitatory connections is markedly different among layers of SC; the SGI neurons form extensive lateral excitatory connections, whereas they are sparse or limited within subsets of neurons in the stratum griseum superficiale (SGS). Wide-field vertical neurons in the stratum opticum have features intermediate between neurons in the SGS and SGI. Such differences in the structure of lateral excitatory connections may reflect the different way signal processing is achieved in each layer of SC.
Afferent-Induced Changes in Rhythmic Motor Programs in the Feeding Circuitry of Aplysia
Authors: Shetreat-Klein Avniel N. , Cropper Elizabeth C.
Published: June 2004

A manipulation often used to determine whether a neuron plays a role in the generation of a motor program involves injecting current into the cell during rhythmic activity to determine whether activity is modified. We perform this type of manipulation to study the impact of afferent activity on feeding-like motor programs in Aplysia. We trigger biting-like programs and manipulate sensory neurons that have been implicated in producing the changes in activity that occur when food is ingested, i.e., when bites are converted to bite-swallows. Sensory neurons that are manipulated are the radula mechanoafferent B21 and the retraction proprioceptor B51. Data suggest that both cells are peripherally activated during radula closing/retraction when food is ingested. We found that phasic subthreshold depolarization of a single sensory neuron can significantly prolong radula closing/retraction, as determined by recording both from interneurons (e.g., B64), and motor neurons (e.g., B15 and B8). Additionally, afferent activity produces a delay in the onset of the subsequent radula opening/protraction, and increases the firing frequency of motor neurons. These are the changes in activity that are seen when food is ingested. These results add to the growing data that implicate B21 and B51 in bite to bite-swallow conversions and indicate that afferent activity is important during feeding in Aplysia.
Voltage-Gated Ion Channels in Nociceptors: Modulation by cGMP
Authors: Liu L. , Yang T. , Bruno M. J. , Andersen O. S. , Simon S. A.
Published: June 2004

In tissue or nerve injury, proinflammatory mediators are released that can modulate a variety of ion channels found in nociceptors. The changes in channel activity, which primarily occurs through changes in intracellular pathways, may lead to the pathological states of hyperalgesia and allodynia. To understand further the regulatory mechanisms underlying the changes in channel activity, we used whole cell patch-clamp recordings from capsaicin-sensitive nociceptive neurons in rat trigeminal ganglion neurons to examine how the cGMP-dependent pathways may regulate ion channel function. Addition of the 8-(4-chlorophenylthio)-3′,5′ (CPT)-cGMP, a membrane permeant modulator of ion channels, decreased the number of evoked action potentials by 36% and inhibited the tetrodotoxin-resistant (TTX-R) sodium currents and IA potassium currents by 37 and 32%, respectively. Delayed rectifier potassium ( IK) currents were unaffected, suggesting that the effects of CPT-cGMP are unlikely to arise from a nonspecific effect on channel activity as a consequence of the adsorption of amphipathic CPT-cGMP molecules to the membrane's bilayer component. This conclusion was reinforced by the lack of changes in gramicidin A channel function in the presence of CTP-cGMP. In summary, the activation of the cGMP-dependent pathways reduces nociceptor excitability, in part, by decreasing the activity of voltage-gated TTX-R sodium channels. This pathway may be a target for efforts to produce selective analgesics.
Optical Mapping Reveals Developmental Dynamics of Mg2+-/APV-Sensitive Components of Glossopharyngeal Glutamatergic EPSPs in the Embryonic Chick NTS
Authors: Sato Katsushige , Momose-Sato Yoko
Published: June 2004

To examine whether there are any differences in functional organization between the glossopharyngeal nerve (N. IX)– and vagus nerve (N. X)–projecting areas in the nucleus of the tractus solitarius (NTS), we performed optical recording of neural responses evoked by N. IX stimulation in 5- to 9-day-old embryonic chick brain stem preparations and compared the results with those in our previous studies concerning the N. X-related NTS. First, we investigated dl-2-amino-5-phosphonovaleric acid (APV)/Mg2+sensitivity of the glutamatergic excitatory postsynaptic potentials (EPSPs) in the N. IX-related NTS. In 7- to 9-day-old preparations, we found regional differences in the degree of both the APV-induced reduction and Mg2+-free–induced enhancement of the EPSPs. We constructed developmental maps of spatial patterns of the APV- and Mg2+-sensitive components and showed that functional expression of the N-methyl-d-aspartate (NMDA) receptor dynamically changed during development. Second, we studied initial expression of synaptic functions in the N. IX-related NTS. In 6-day-old preparations, although action potentials alone were usually detected in normal Ringer solution, small EPSPs were elicited in a Mg2+-free solution. This result suggests that the NMDA receptor–mediated synaptic function is latently generated in the N. IX-related NTS at the 6-day-old embryonic stage and that external Mg2+regulates the onset of synaptic functions. Developmental patterns of APV/Mg2+sensitivity and the stage of initial expression of the glossopharyngeal EPSP were similar to those of the N. X, suggesting that the developmental sequence of the synaptic function in the NTS is the same for the N. IX- and N. X-related NTS.
Phenotypic and genetic analyses of subcongenic BB.SHR rat lines shorten the region on chromosome 4 bearing gene(s) for underlying facets of metabolic syndrome
Authors: Klöting Nora , Wilke Barbara , Klöting Ingrid
Published: June 2004

Congenic BB.SHR ( D4Got41-Npy-Tacr1; BB.4S) rats develop an incomplete metabolic syndrome with obesity, hyperleptinemia, and dyslipidemia compared with their progenitor strain, the diabetes-prone BB/OK rat. To narrow down the underlying gene(s), two subcongenic BB.SHR rat lines, briefly termed BB.4Sa and BB.4Sb, were generated. Male BB.4S ( n = 20), BB.4Sa ( n = 24), and BB.4Sb ( n = 26) were longitudinally characterized for facets of the metabolic syndrome and analyzed for expression of genes located in the region of interest in liver and blood. Body weight gain was comparable, serum triglycerides and leptin were significantly increased, and total cholesterol and HDL-cholesterol ratio were decreased in BB.4S compared with both subcongenics. Serum insulin was significantly higher in BB.4S and BB.4Sa than in BB.4Sb. The adiposity index showed a graduated decrease from BB.6S to BB.4Sb. Obvious differences in relative expression were found in 6 of 10 genes in liver and in 2 of 9 genes in blood. Only one gene, the eukaryotic translation initiation factor 2α kinase 3 ( Eif2ak3 also called Perk or Pek), was significantly less expressed in liver and in blood of both subcongenic BB.4Sa and BB.4Sb compared with their “parental” BB.4S rats. Based on the phenotype and genotype in BB.4S and its subcongenic derivatives, the most important region on chromosome 4 can be said to lie between D4Got72 and Tacr1. Eif2ak3 is mapped in this region. Considering the function of Eif2ak3, it may be a candidate gene for the development of glucose intolerance found in both subcongenics but not in BB.4S. Allelic variants between BB/OK and SHR could influence Eif2ak3 function, possibly leading not only to glucose intolerance but also to the disturbances in hepatic and renal function found in human Wolcott-Rallison syndrome.
Structure of AFeTi(PO4)3 (A=Ca,Cd) Nasicon phases from powder X-ray data
Authors: Aatiq Abderrahim , Dhoum Hicham
Published: June 2004

AFeTi(PO4)3 (A=Ca,Cd) materials were obtained by solid state reaction in air at 1000 °C. Structures of the two compounds were determined from X-ray diffraction data using Rietveld analysis. Both phases exhibit the Nasicon-type structure (R3¯c space group) with a statistical Fe(Ti) distribution within the framework. Their hexagonal cell parameters are a=8.518(1) Å, c=21.797(2) Å and a=8.534(1) Å, c=21.416(2) Å, for CaFeTi(PO4)3 and CdFeTi(PO4)3, respectively. Cd atoms occupy the M1 site in CdFeTi(PO4)3. From XRD data, it is difficult to distinguish without ambiguity between Ca2+ and Ti4+ ions in CaFeTi(PO4)3. Nevertheless from the cation–anion distance found after the structure determination, Ca2+ distribution within the M1 site of Nasicon structure are validated.
Conformational phase transition of deuterated p-bromobenzyl alcohol as studied by neutron powder diffraction
Authors: Mizuno M. , Hamada M. , Hashimoto M. , Harada M. , Eda K. , Yamamura K. , Kamiyama T. , Oikawa K.
Published: June 2004

A neutron powder diffraction study on the crystal structure of the title compound (p-Br–C6D4–CD2–OD) confirmed that a first-order phase transition at Tt1=229 K accompanied a drastic change in the molecular conformation caused by a discontinuous rotational shift of the hydroxyl hydrogen atom around the C(D2)–O(D) bond. At T<Tt1, a contraction of the unit cell volume of ∼1% was found when compared to that of the normal compound (p-Br–C6H4–CH2–OH).
Crystal structure of dicalcium chromate hydrate
Authors: Botez C. E. , Stephens P. W. , Omotoso Oladipo
Published: June 2004

Direct methods and Rietveld analysis were applied to high-resolution synchrotron X-ray powder diffraction data to solve the crystal structure of dicalcium chromate hydrate (Ca2CrO5⋅3H2O). The compound crystallizes in monoclinic symmetry (space group Cm, Z=2), with a=8.23575(5) Å, b=7.90302(4) Å, c=5.20331(3) Å, and β=98.0137(3)°. The structure is built from double-layers of CrO4 tetrahedra and CaO8 polyhedra that run parallel to the (001) plane.
High quality powder diffraction data for A-type zeolite with selected divalent d-electron metals
Authors: Pikus S. , Olszewska E. , Majdan M. , Pajak L.
Published: June 2004

Six A-type zeolites: NaA, MnNaA, CoNaA, NiNaA, ZnNaA, CdNaA have been characterized by X-ray powder diffraction. The zeolites with selected divalent cations have been synthesized by a very careful ion-exchange process using very high quality NaA zeolite. Experimental 2θ peak positions, relative peak intensities, values of d and Miller indices as well as a unit cell parameter are reported.
Microdiffraction phase identification in the scanning electron microscope (SEM)
Authors: Goehner R. P. , Michael J. R.
Published: June 2004

The identification of crystallographic phases in the scanning electron microscope (SEM) has been limited by the lack of a simple way to obtain electron diffraction data of an unknown while observing the microstructure of the specimen. With the development of charge coupled device (CCD)-based detectors, backscattered electron Kikuchi patterns, alternately referred to as electron backscattered diffraction (EBSD) patterns, can be easily collected. Previously, EBSD has been limited to crystallographic orientation studies due to the poor pattern quality collected with video rate detector systems. With CCD detectors, a typical EBSD can now be acquired from a micron or submicron sized crystal using an exposure time of 1–10 s with an accelerating voltage of 10–40 kV and a beam current as low as 0.1 nA. Crystallographic phase analysis using EBSD is unique in that the properly equipped SEM permits high magnification images, EBSDs, and elemental information to be collected from bulk specimens. EBSD in the SEM has numerous advantages over other electron beam-based crystallographic techniques. The large angular view (∼70°) provided by EBSD and the ease of specimen preparation are distinct advantages of the technique. No sample preparation beyond what is commonly used for SEM specimens is required for EBSD.
Incidence of Obesity-Associated Cardiovascular Disease Is Related to Inflammation-Sensitive Plasma Proteins
Authors: Engström Gunnar , Hedblad Bo , Stavenow Lars , Jonsson Susanna , Lind Peter , Janzon Lars , Lindgärde Folke
Published: June 2004

Background—

Although obesity is associated with increased inflammation, it is unclear whether this accounts for the increased cardiovascular risk in obesity. This population-based study explored whether inflammation-sensitive plasma proteins (ISPs) modify the cardiovascular risk in overweight or obese men.

Methods and Results—

The ISPs (fibrinogen, orosomucoid, α1-antitrypsin, haptoglobin, ceruloplasmin) were measured in 6075 healthy men, aged 28 to 61 years. The incidences of cardiovascular events (myocardial infarction, stroke, cardiovascular deaths), cardiac events (fatal or nonfatal myocardial infarction), and stroke were followed-up over 18±4 years. High ISPs were associated with an increased cardiovascular risk in all categories of body mass index (BMI). The age-adjusted relative risks for cardiovascular events in obese men (BMI >30) were 2.1 (95% CI, 1.4 to 3.4), 2.4 (CI, 1.5 to 3.7), 3.7 (CI, 2.3 to 6.0), and 4.5 (CI, 3.0 to 6.6), respectively, for those with 0, 1, 2, and ≥3 ISPs in the top quartile (trend
P
=0.002) (reference: BMI <25 and no elevated ISP). This trend persisted after adjustments for several potential confounders (
P
=0.02). Incidence of cardiac events showed similar relations with the number of elevated ISPs in obese men.

Conclusion—

The cardiovascular risk varies widely between obese or overweight men with high and low ISPs. Relationships with ISPs contribute to, but cannot fully explain, the increased cardiovascular risk in obese men.
Thrombomodulin-Protein C-EPCR System
Authors: de Wouwer Marlies Van , Collen Désiré , Conway Edward M.
Published: June 2004

Late in the 18th century, William Hewson recognized that the formation of a clot is characteristic of many febrile, inflammatory diseases (Owen C.A History of Blood Coagulation. Rochester, Minnesota: Mayo Foundation; 2001). Since that time, there has been steady progress in our understanding of coagulation and inflammation, but it is only in the past few decades that the molecular mechanisms linking these 2 biologic systems have started to be delineated. Most of these can be traced to the vasculature, where the systems most intimately interact. Thrombomodulin (TM), a cell surface-expressed glycoprotein, predominantly synthesized by vascular endothelial cells, is a critical cofactor for thrombin-mediated activation of protein C (PC), an event further amplified by the endothelial cell protein C receptor (EPCR). Activated PC (APC), in turn, is best known for its natural anticoagulant properties. Recent evidence has revealed that TM, APC, and EPCR have activities that impact not only on coagulation but also on inflammation, fibrinolysis, and cell proliferation. This review highlights recent insights into the diverse functions of this complex multimolecular system and how its components are integrated to maintain homeostasis under hypercoagulable and/or proinflammatory stress conditions. Overall, the described advances underscore the usefulness of elucidating the relevant molecular pathways that link both systems for the development of novel therapeutic and diagnostic targets for a wide range of inflammatory diseases.
Rat Aortic MCP-1 and Its Receptor CCR2 Increase With Age and Alter Vascular Smooth Muscle Cell Function
Authors: Spinetti Gaia , Wang Mingyi , Monticone Robert , Zhang Jing , Zhao Di , Lakatta Edward G.
Published: June 2004

Objective—With age, rat arterial walls thicken and vascular smooth muscle cells (VSMCs) exhibit enhanced migration and proliferation. Monocyte chemotactic protein-1 (MCP-1) affects these VSMC properties in vitro. Because arterial angiotensin II, which induces MCP-1 expression, increases with age, we hypothesized that aortic MCP-1 and its receptor CCR2 are also upregulated and affect VSMC properties.

Methods and Results—Both MCP-1 and CCR2 mRNAs and proteins increased in old (30-month) versus young (8-month) F344×BN rat aortas in vivo. Cellular MCP-1 and CCR2 staining colocalized with that of α-smooth muscle actin in the thickened aortas of old rats and were expressed by early-passage VSMCs isolated from old aortas, which, relative to young VSMCs, exhibited increased invasion, and the age difference was abolished by vCCI, an inhibitor of CCR2 signaling. MCP-1 treatment of young VSMCs induced migration and increased their ability to invade a synthetic basement membrane. The MCP-1–dependent VSMC invasiveness was blocked by vCCI. After MCP-1 treatment, migration and invasion capacities of VSMCs from young aortas no longer differed from those of VSMCs isolated from older rats.

Conclusions—Arterial wall and VSMC MCP-1/CCR2 increase with aging. MCP-1 enhances VSMC migration and invasion, and thus, MCP-1/CCR2 signaling may play a role in age-associated arterial remodeling.