bluuebunny/crossref_metadata_2025 huggingface dataset:
Verapamil metabolites: potential P-glycoprotein-mediated multidrug resistance reversal agents
Authors: Woodland Cindy , Koren Gideon , Wainer Irving W , Batist Gerry , Ito Shinya
Published: September 2003

Multidrug resistance in cancer chemotherapy frequently correlates with overexpression of the P-glycoprotein drug transporter. Attempts to reverse P-glycoprotein-mediated multidrug resistance with racemic verapamil or its less toxic (R)-enantiomer have been complicated by cardiotoxicity. The objective of this study was to investigate the effects of the major verapamil metabolite, norverapamil, as well as the PR-22 and D-620 metabolites, on P-glycoprotein-mediated drug transport. We measured the basolateral-to-apical fluxes of the P-glycoprotein substrates digoxin and vinblastine in the presence and absence of verapamil, (R)-norverapamil, (S)-norverapamil, racemic norverapamil, PR-22, or D-620 across confluent monolayers of MadinDarby canine kidney (MDCK) cells that express P-glycoprotein on their apical membranes. Verapamil and norverapamil nonstereospecifically inhibited the renal tubular secretion of digoxin and vinblastine similarly in a dose-dependent manner. However, there was no decrease in the cellular accumulation of digoxin and vinblastine, suggesting that neither verapamil nor norverapamil prevent the substrates from entering the MDCK cells. Furthermore, the norverapamil metabolite P-22 also inhibited the secretion of these P-glycoprotein substrates. Our results suggest that the verapamil metabolites norverapamil and PR-22, which are less cardiotoxic than the parent compound, have comparable inhibitory abilities to verapamil (norverapamil greater than PR-22) and may be useful in reversing resistance to P-glycoprotein substrates.Key words: verapamil, norverapamil, PR-22, kidney, P-glycoprotein.
The physiology ofS-nitrosothiols: carrier molecules for nitric oxide
Authors: Ng Ella S.M , Kubes Paul
Published: September 2003

Recent work has demonstrated that inhalation of nitric oxide (NO) can impact the peripheral vasculature, suggesting that an NO-stabilizing moiety may exist in vivo. One possibility is the formation of S-nitrosothiols, which extend the half-life of NO manyfold. In this review, we provide evidence that S-nitrosothiols exist in the vasculature, particularly during NO inhalation. The potential biochemical pathways that have been proposed for the formation of these products are also summarized. Finally, we highlight the limited evidence for the role that these potent vasodilating molecules may play as physiologically and therapeutically important regulators of the vascular system.Key words: inhaled NO, S-nitroso-albumin, peripheral circulation.
Potential beneficial as well as detrimental effects of chronic treatment with lisinopril and (or) spironolactone on isolated hearts following low-flow ischemia in normal and infarcted rats
Authors: Rochetaing Annie , Chapon Catherine , Marescaux Laurent , Bouil Anne Le , Furber Alain , Kreher Paul
Published: September 2003

This study was designed to demonstrate potential beneficial as well as detrimental effects of lisinopril and spironolactone given in combination. In patients with congestive heart failure or myocardial infarction, the use of angiotensin-converting enzyme (ACE) inhibitors may inhibit aldosterone production. Spironolactone, a specific aldo sterone receptor antagonist may exert other independent and additive effects to those of ACE inhibitors. Given the consequences of aldosterone on ischemic hearts, we evaluated the protective effects of spironolactone or lisinopril and combined spironolactonelisinopril therapy during low-flow ischemia and reperfusion in isolated rat hearts. Normal and infarcted (left coronary artery ligature) male Wistar rats were submitted to chronic action of drugs (0.8 mg·kg1·day1 for lisinopril and 8 or 50 mg·kg1·day1 for spironolactone) for 1 month. Hearts were rapidly excised and perfused (constant pressure) for a 40-min period of stabilization followed by a 25-min period of global low-flow ischemia and a 30-min reperfusion. In normal rats, spironolactone decreased ischemic and reperfusion contracture, reduced ventricular tachycardia, suppressed action-potential duration dispersion, and increased reactive hyperemia leading to an improvement of contractile recovery. Lisinopril also decreased ventricular tachycardia and action-potential duration dispersion concomitantly with increased reactive hyperemia and better contractile recovery. These beneficial effects of the drugs were lost when the two treatments were combined (lisinopril and 50 mg·kg1·day1 spironolactone), despite a synergistic effect on plasmatic K+ and Mg2+. However, an interaction between the ACE inhibitor and spironolactone potentiating the effects of either drug alone was observed with a lower dose of spironolactone (lisinopril and 8 mg·kg1·day1 spironolactone). Similar beneficial effects have been noted in infarcted rat hearts on reactive hyperemia, ventricular tachycardia, and contractile recovery with the combined treatment and for both spironolactone concentrations (8 or 50 mg). Chronic spironolactone treatment produces similar beneficial effects to ACE inhibitor treatment on normal rat hearts during an ischemia-reperfusion protocol. Synergistic effects have been observed with the combined therapy when a lower dose of spironolactone was utilized in normal and infarcted rats. However, in the case of a high dose of spironolactone, the two effective drugs seem to cancel each other but only in normal rats.Key words: spironolactone, ACE inhibitors, ischemiareperfusion, ventricular arrhythmia, action potentials, coronary flow, congestive heart failure.
Effects of desmopressin on prolonging survival in stable hypothermia in rats
Authors: Lee Tze-fun , Wang Lawrence C.H
Published: September 2003

The aim of the present study was to examine whether minimizing plasma volume loss due to cold-induced diuresis can increase the survival time of rats maintained in long-term stable hypothermia (~24 h at a body temperature of 19°C). Infusion of desmopressin (0.5-2.0 μg), a potent antidiuretic agent, during the cooling period enhanced survival over saline controls in a dose-related manner. The enhanced survival was accompanied by a significant delay in the expected increase of hematocrit and decrease of plasma volume as compared with those seen in saline controls. In contrast, treating the rats with the same dose range of another vasopressin analog, [β-mercapto-β,β-cyclopentamethyl enepropionyl]-vasopressin, which has no antidiuretic action, failed to enhance survival over saline control. Further, treating the rats with the optimal dose of desmopressin (1 μg) at the later stage of hypothermia failed to elicit any beneficial effect. Our results indicate that by using desmopressin early during the cooling phase of the hypothermia, plasma volume and rheological parameters important for sustaining microcirculation can be better maintained than those seen in saline controls. These improvements may have contributed to the observed longer survival time in hypothermia.Key words: microcirculation, desmopressin, hematocrit, plasma volume, cold-induced diuresis.
Spontaneous baroreflex sensitivity after coronary artery bypass graft surgery as a function of gender and age
Authors: Brown C Ann , Wolfe Larry A , Hains Sylvia , Ropchan Glorianne , Parlow Joel
Published: September 2003

The effects of coronary artery bypass graft (CABG) surgery on spontaneous baroreflex (SBR) sensitivity and heart rate variability were examined in 11 women and 23 men preoperatively and 5 days postoperatively. Electrocardiograph RR interval and beat-by-beat arterial blood pressure data were collected continuously for 20 min in the supine and standing postures. Coarse graining spectral analysis was performed on the heart rate variability data. Spontaneous baroreflex sensitivity declined after surgery with a differential influence of gender. Men showed a decrease in SBR slope following surgery, with a greater decrease in the standing posture; the parasympathetic (PNS) indicator was lower postoperatively and in the standing posture; the reduction in low-frequency (LF) power was greater for the younger men. In women, the PNS indicator was lower in the standing posture. Both men and women showed a decrease in high-frequency power following CABG surgery, which decreased the sensitivity of the short-term cardiac control mechanisms that modulate heart rate, with the greater effects occurring in men. The reduction in SBR sensitivity indicates that the ability of the cardiovascular system to respond rapidly to changing stimuli was compromised. The decline in the PNS indicator implies that patients were vulnerable to the risks of myocardial ischemia, sympathetically mediated cardiac dysrhythmias, and sudden cardiac death.Key words: spectral analysis, spontaneous baroreflex sensitivity, CABG surgery, gender, age, posture.
Hypothyroidism does not affect the dihydropyridine sensitivity of precontracted murine uterus
Authors: Wegener Jörg W , Lee Matthias , Hofmann Franz
Published: September 2003

Thyroid hormones are known to influence various processes of cell differentiation. Recently, it was reported that hypothyroidism reduces the sensitivity to Ca2+-channel antagonists in the rat uterus. We examined the sensitivity to dihydropyridines of the uterus from mice that had reduced thyroid hormone levels. Isradipine relaxed with the same potency precontracted uterine muscle strips from control and hypothyroid mice, independently from a pseudo-pregnant state. These results demonstrate that hypothyroidism does not change dihydropyridine sensitivity (i.e., the pattern of Ca2+-channel expression) in the murine uterus.Key words: uterus, smooth muscle, Ca2+channel, isradipine.
Seasonal diving patterns and body temperatures of juvenile green turtles at Heron Island, Australia
Authors: Southwood Amanda L , Reina Richard D , Jones Vivienne S , Jones David R
Published: September 2003

This study compared diving patterns of juvenile green turtles, Chelonia mydas, in a coral reef habitat during summer and winter. Dataloggers were deployed on green turtles at Heron Island, Australia, during December 2000 and August 2001 so that dive variables and ambient water temperature (TW) could be monitored. Cloacal temperatures (TB) were recorded from green turtles upon capture to assess their ability to maintain a thermal gradient between TBand TW. Data show that green turtles altered diving behaviour seasonally. Green turtles spent significantly more time in shallow water (<1 m) during winter than during summer. Dive depth for dives that exceeded 1 m was 2.9 ± 0.4 m (mean ± SEM) during summer and 4.4 ± 0.6 m during winter. Dive duration in summer (13.1 ± 1.2 min) was approximately half the dive duration in winter (24.3 ± 1.6 min), and surface interval in summer (0.6 ± 0.1 min) was one-third that of the surface interval in winter (1.8 ± 0.1 min). The observed changes in behaviour may be due to seasonal changes in environmental and physiological factors. There was no statistically significant difference between TBand TWduring summer or winter.
Parental roles and mating system in the black-winged stilt
Authors: Cuervo J J
Published: September 2003

The breeding behaviour of black-winged stilts (Himantopus himantopus) was studied in southwestern Spain. In the prelaying period males devoted more time than females to agonistic encounters, locomotion, and nest building. During egg laying, males spent more time than females at the nest, mostly building the nest and covering the eggs, while females spent more time foraging than males. During late incubation, females spent significantly more time at the nest than males. These results suggest very similar parental investment by the sexes. During part of the female's fertile period, males stayed at the nest while females were foraging, which precluded efficient mate guarding. However, females were reluctant to engage in extra-pair copulations, being always very aggressive towards conspecifics except for their mates. Even in two cases of extra-pair copulation, the first described for this species, the female continuously attacked the intrusive male and did not cooperate in copulation. Male parental care seems to be essential for reproductive success and females are probably faithful in order to assure male parental investment. The need for parental care from both males and females would maintain social, and perhaps also genetic, monogamy in this species.
Effect of turbulence on the mortality of zebra mussel veligers
Authors: Rehmann C R , Stoeckel J A , Schneider D W
Published: September 2003

Small-scale turbulence can increase the mortality of zebra mussel (Dreissena polymorpha) veligers. Laboratory experiments were conducted in which veligers were subjected to turbulence due to a bubble plume and the rate of dissipation of turbulent kinetic energy was measured directly. The ratio d* of the shell size and the Kolmogorov length, the size of the smallest eddy in the velocity field, is introduced to quantitatively assess whether turbulence can affect larvae. The laboratory experiments show that mortality increases when d* exceeds 0.9, that is, when the size of the larvae is comparable with or larger than the smallest eddy. The laboratory results are used to show that turbulence can increase veliger mortality in streams and to evaluate the possibility of using bubble screens as a dispersal barrier to control zebra mussels in rivers. If the mortality is due to acute effects of turbulence (taken to be exposure on the order of minutes), the control scheme would work, but if the mortality is due to longer-term exposure, using bubble screens would not be practical.
Life history and production of mayflies, stoneflies, and caddisflies (Ephemeroptera, Plecoptera, and Trichoptera) in a spring-fed stream in Prince Edward Island, Canada: evidence for population asynchrony in spring habitats?
Authors: Dobrin Michelle , Giberson Donna J
Published: September 2003

We examined the life history and production of the Ephemeroptera, Plecoptera, and Trichoptera (EPT) community along a 500-m stretch of a hydrologically stable cold springbrook in Prince Edward Island during 1997 and 1998. Six mayfly species (Ephemeroptera), 6 stonefly species (Plecoptera), and 11 caddisfly species (Trichoptera) were collected from benthic and emergence samples from five sites in Balsam Hollow Brook. Eleven species were abundant enough for life-history and production analysis: Baetis tricaudatus, Cinygmula subaequalis, Epeorus (Iron) fragilis, and Epeorus (Iron) pleuralis (Ephemeroptera), Paracapnia angulata, Sweltsa naica, Leuctra ferruginea, Amphinemura nigritta, and Nemoura trispinosa (Plecoptera), and Parapsyche apicalis and Rhyacophila brunnea (Trichoptera). Life-cycle timing of EPT taxa in Balsam Hollow Brook was generally similar to other literature reports, but several species showed extended emergence periods when compared with other studies, suggesting a reduction in synchronization of life-cycle timing, possibly as a result of the thermal patterns in the stream. Total EPT secondary production (June 1997 to May 1998) was 2.742.80 g·m2·year1dry mass (size-frequency method). Mayflies were dominant, with a production rate of 2.2 g·m2·year1dry mass, followed by caddisflies at 0.41 g·m2·year1dry mass, and stoneflies at 0.19 g·m2·year1dry mass. More than half of the species found in the study stream represented new distribution records for Prince Edward Island.
Seasonal variations in population and community structure of small rodents in a tropical forest of Gabon
Authors: Nicolas Violaine , Colyn Marc
Published: September 2003

The composition, structure, and reproductive phenology of a community of murid rodents were investigated for 1 year at two sites in an undisturbed forest in southwestern Gabon, Africa. We captured 1531 mice belonging to 11 species and eight genera. At both sites, species richness varied seasonally and tended to be maximal during the period of maximal trap success. For the most abundant species (Hylomyscus stella, Hybomys univittatus, Heimyscus fumosus, and Praomys cf. misonnei), a general unimodal trend in trap success was detected, owing to variations in breeding activity and survival, with a minimum around the long rainy season and a maximum either during the short rainy season or at the beginning of the following long dry season. These fluctuations varied in magnitude among species, and seasonal variations in relative abundance were recorded. Our results support the assumption that in the tropics, rainfall and associated patterns of fruit and insect abundance are important factors which may act directly or indirectly to initiate breeding activity so that lactation occurs at a time of greatest food abundance. Finally, intrapopulational differences in age at sexual maturity were found, both between the sexes and among individuals of the same sex.
Red squirrels and predation risk to bird nests in northern forests
Authors: Willson Mary F , Santo Toni L. De , Sieving Kathryn E
Published: September 2003

Red squirrels (Tamiasciurus hudsonicus) are important predators on bird nests in northern conifer forests, and previous work has shown that nest density of understory birds is low in these forests compared with deciduous forest. Here, we examine the relationships between the risk of squirrel predation and nest distribution at a smaller, within-habitat scale using both experimental and comparative studies. Female squirrels depredated experimental nests more quickly than males in interior forests near the Yukon  British Columbia border, but after 2 weeks, there was no difference in the percentage of nests depredated by males and females. The density of squirrels and the risk of experimental nest predation increased but the index of natural nest density did not decrease with the density of cone-bearing Sitka spruce (Picea sitchensis) trees in coastal conifer forests of Southeast Alaska. Experimental nests in successional deciduous stands had high risks of predation, in part because squirrels occupied small stands of colonizing spruces in the deciduous matrix and foraged widely in the deciduous stands. In the experimental study site, natural nests occurred at similar densities both next to and away from squirrel-occupied spruce stands, but in other areas, there was a "halo" of low nest density in deciduous vegetation next to spruce stands. Overall, there was little evidence that, within habitats, birds chose nest sites that minimized the risk of squirrel predation.
Group composition and cohesion in sympatric white-tailed deer and mule deer
Authors: Lingle Susan
Published: September 2003

White-tailed deer (Odocoileus virginianus) have been reported to live in smaller groups than mule deer (Odocoileus hemionus). Group size, however, generally varies with habitat conditions, and no comparison has been made between the social structures of the two species living in the same ecological conditions. I compared the size, composition, and stability of groups formed by sympatric whitetails and mule deer living in a prairie habitat in southern Alberta. Seasonal trends were similar for the two species. Females and fawns usually formed small groups during summer. Larger mixed-sex groups became increasingly common during winter, well after the breeding season. Despite the similar seasonal trend, mule deer were significantly more likely than whitetails to occur in relatively large groups composed of both sexes during winter, and whitetails were more likely to occur in small female groups. Mule deer groups were more stable than whitetail groups, and marked mule deer fawns developed strong associations with other known fawns. Habitat variation was limited and was not related to group size. These results show that the composition and cohesion of whitetail and mule deer groups differ, even when the species live in similar circumstances. The differences in grouping behaviour, larger more cohesive groups formed by mule deer than by whitetails, are consistent with those expected to result from the selection pressure of predation.
Costs and benefits of joining South American sea lion breeding groups: testing the assumptions of a model of female breeding dispersion
Authors: Cassini M H , Fernández-Juricic E
Published: September 2003

A recent cost-benefit model has been proposed (M.H. Cassini. 1999. Behav. Ecol. 10: 612616; M.H. Cassini. 2000. Behav. Processes, 51: 9399) to predict the dispersion of female mammals when breeding resources are distributed in fixed and predictable patches. The benefit of the model is a reduction in male harassment when females join breeding groups, and the cost is an increase in femalefemale competition for breeding resources. We tested the main assumptions of this model in a breeding colony of South American sea lions (Otaria flavescens), a sexually dimorphic, polygynous pinniped. The rate of femalefemale agonistic interactions increased with the number of females, which suggests that higher levels of femalefemale competition in denser breeding groups could reduce pup survival, owing to motherpup separation effects. The rate of malefemale interactions per female decreased with the number of females defended by a male, the trend being nonlinear, and males did not modify the frequency of interaction with females according to variations in the size of breeding groups. This evidence supports the advantage of female gregariousness in reducing the reproductive costs of interacting with males. We concluded that avoidance of male disturbance through dilution effects may have played an important role in the evolution of this species' mating system.
Influence of Ribeiroia ondatrae (Trematoda: Digenea) infection on limb development and survival of northern leopard frogs (Rana pipiens): effects of host stage and parasite-exposure level
Authors: Schotthoefer Anna M , Koehler Anson V , Meteyer Carol U , Cole Rebecca A
Published: September 2003

Recent evidence suggests that infection by larvae of the trematode Ribeiroia ondatrae accounts for a significant proportion of limb malformations currently observed in amphibian populations of North America. However, the effects of R. ondatrae infection on northern leopard frogs (Rana pipiens), one of the species most frequently reported with malformations, have not been adequately explored. Moreover, the risk factors associated with R. ondatrae-induced malformations have not been clearly identified. We examined the effects of timing of infection on tadpole survival and limb development. Rana pipiens tadpoles were individually exposed to R. ondatrae cercariae at the pre-limb-bud (Gosner stages 24 and 25), limb-bud (Gosner stages 27 and 28), or paddle (Gosner stages 3133) stages of development and monitored through metamorphosis. The effects of infection were stage-specific. Infections acquired at the pre-limb-bud stage resulted in a high mortality rate (47.597.5%), whereas tadpoles infected at the limb-bud stage displayed a high malformation rate (16% overall), and the magnitude of effects increased with the level of exposure to cercariae. In contrast, infections acquired at the paddle stage had no effect on limb development or tadpole survival, which suggests that the timing of R. ondatrae infection in relation to the stage structure of tadpole populations in the wild is an important determinant of the degree to which populations are affected by R. ondatrae.
R2-Corrections to Chaotic Inflation
Authors: Cárdenas Víctor H. , del Campo Sergio , Herrera Ramón
Published: September 2003

Scalar density cosmological perturbations, spectral indices and reheating in a chaotic inflationary universe model, in which a higher derivative term is added, are investigated. This term is supposed to play an important role in the early evolution of the Universe, specifically at times closer to the Planck era.
On the Lorentz Transformations of Momentum and Energy
Authors: Toller M.
Published: September 2003

Motivated by ultra-high-energy cosmic ray physics, we discuss all the possible alternatives to the familiar Lorentz transformations of the momentum and the energy of a particle. Starting from natural physical requirements, we exclude all the possibilities, apart from the ones which arise from the usual four-vector transformations by means of a change of coordinates in the mass-shell. This result confirms the remark, given in a preceding paper, that, in a theory without preferred inertial frames, one can always define a linearly transforming energy parameter to which the GZK cutoff argument can be applied. We also discuss the connections between the conservation and the transformation properties of energy–momentum and the relation between energy–momentum and velocity.
Asymptotics of integrodifferential modelswith integrable kernels II
Authors: Bijura Angelina M.
Published: September 2003

Nonlinear singularly perturbed Volterra integrodifferential
equations with weakly singular kernels are investigated using
singular perturbation methods, the Mellin transform technique, and
the theory of fractional integration.
New Developments in Transmission Electron Microscopy for Nanotechnology
Authors: Wang Z.L.
Published: September 2003

High‐resolution transmission electron microscopy (HRTEM) is one of the most powerful tools used for characterizing nanomaterials, and it is indispensable for nanotechnology. This paper reviews some of the most recent developments in electron microscopy techniques for characterizing nanomaterials. The review covers the following areas: in‐situ microscopy for studying dynamic shape transformation of nanocrystals; in‐situ nanoscale property measurements on the mechanical, electrical and field emission properties of nanotubes/nanowires; environmental microscopy for direct observation of surface reactions; aberration‐free angstrom‐resolution imaging of light elements (such as oxygen and lithium); high‐angle annular‐dark‐field scanning transmission electron microscopy (STEM); imaging of atom clusters with atomic resolution chemical information; electron holography of magnetic materials; and high‐spatial resolution electron energy‐loss spectroscopy (EELS) for nanoscale electronic and chemical analysis. It is demonstrated that the picometer‐scale science provided by HRTEM is the foundation of nanometer‐scale technology.
Highly Circularly Polarized Photoluminescence over a Broad Spectral Range from a Calamitic, Hole‐Transporting, Chiral Nematic Glass and from an Indirectly Excited Dye
Authors: Woon K.L. , O'Neill M. , Richards G.J. , Aldred M.P. , Kelly S.M. , Fox A.M.
Published: September 2003

A highly birefringent, luminescent chiral nematic liquid crystal is shown to have an extremely broad photonic stop band (see dashed line in Figure) overlapping its emission spectrum. Highly circularly polarized photoluminescence is observed from the liquid crystal itself and from an indirectly excited dye dopant. The liquid crystal is hole‐transporting with a room‐temperature mobility of 4 × 10–4 cm2 V–1 s–1.
Microgel‐Stabilized Metal Nanoclusters: Size Control by Microgel Nanomorphology
Authors: Biffis A. , Orlandi N. , Corain B.
Published: September 2003

Soluble crosslinked macromolecules (microgels) used as stabilizers of catalytically active metal nanoclusters allow control of the nanocluster size by simply changing the crosslinking degree of the microgel. Microgel‐stabilized metal nanoclusters are easily prepared and stored in the solid state, and those of Pd (see Figure) exhibit high catalytic activity in the Heck reaction of activated aryl bromides.
Luminescent Nanoring Structures on Silicon
Authors: Prabhakaran K. , Meneau F. , Sankar G. , Sumitomo K. , Murashita T. , Homma Y. , Greaves G.N. , Ogino T.
Published: September 2003

A unique self‐organization of optically active nanoparticles of CdS on a silicon surface forming nanoring structures (see Figure and inside cover) is presented. Tunneling luminescence mapping on these structures show that there is direct correspondence between the morphology and the light emission, suggesting that this novel nanomaterial system could make a significant impact in a wide variety of fields including quantum optics.
Moiré Pattern Formation on Porous Alumina Arrays Using Nanoimprint Lithography
Authors: Choi J. , Wehrspohn R.B. , Gösele U.
Published: September 2003

Porous alumina arrays with various Moiré patterns (see Figure) are prepared by two‐step nanoindentation with different rotation angles and subsequent anodization. The patterns on the porous alumina array are in good agreement with the theory of Moiré patterns in terms of the rotation angles. In addition, replicas of photoresist polymer with the Moiré pattern are successfully prepared.
Sex‐specific patterns of galanin, cholecystokinin, and substance P expression in neurons of the principal bed nucleus of the stria terminalis are differentially reflected within three efferent preoptic pathways in the juvenile rat
Authors: Polston Eva K. , Simerly Richard B.
Published: September 2003

Neurons in the principal bed nucleus of the stria terminalis (BSTp) integrate hormonal and sensory information associated with reproduction and transmit this information to hypothalamic nuclei that regulate neuroendocrine and behavioral functions. The neuropeptides galanin (GAL), cholecystokinin (CCK), and substance P (SP) are highly expressed in BSTp neurons and are differentially regulated by sex steroids. The current experiments investigated whether developmental or peripubertal hormone‐mediated changes in GAL, CCK, and SP expression are reflected within efferent pathways to the preoptic structures that regulate gonadotropin secretion and sexual behavior. Anterograde labeling of projections from the BSTp of male and female juvenile rats combined with immunohistochemical labeling of GAL‐, CCK‐, and SP‐containing fibers in the anteroventral periventricular preoptic nucleus (AVPV) and the central and medial divisions of the medial preoptic nucleus (MPNc, MPNm, respectively) revealed unique sex differences in each region. In the AVPV, Phaseolus vulgaris leucoagglutinin‐labeled fibers were seen at a greater density in males than in females, and higher percentages of these fibers contained GAL in males than in females. In contrast, fibers projecting from the BSTp to the MPNc were more likely to contain SP in females than in males. Treatment of gonadectomized, peripubertal males and females with exogenous testosterone and estradiol did not alter the densities of GAL‐, CCK‐, or SP‐containing fibers in any of the three brain areas examined. Collectively, these results suggest that patterns of neuropeptide expression in BSTp projections are established during development, resulting in a distinct, stable, and sex‐specific chemoarchitectural profile for each projection pathway. J. Comp. Neurol. 465:551–559, 2003. © 2003 Wiley‐Liss, Inc.
Diversity of glycine receptors in the mouse retina: Localization of the α3 subunit
Authors: Haverkamp Silke , Müller Ulrike , Harvey Kirsten , Harvey Robert J. , Betz Heinrich , Wässle Heinz
Published: September 2003

Glycine receptors (GlyRs) and their role in retinal circuitry were analyzed immunocytochemically in wild‐type and GlyR α3 subunit–deficient (Glra3−/−) mouse retinae. GlyRs are localized in the inner plexiform layer in brightly fluorescent puncta, which are likely to represent postsynaptically clustered GlyRs. Approximately one third of the clusters were found to contain the α1 subunit, and half possessed the α3 subunit. However, these two GlyR isoforms were localized at different glycinergic synapses. In the Glra3−/− mouse, α3 subunit clusters were completely eliminated, although the total number of GlyR clusters was only slightly reduced. This finding indicates that other GlyR subunits (such as α2 or α4) may have compensated for the loss of the α3 subunit. Characteristic expression patterns of the α1 and α3 subunits within the synaptic circuits of the retina were revealed by double labeling sections for GlyRs and markers that define specific retinal neurons. The α1 subunit mediates signal transfer in the rod pathway between AII amacrine cells and OFF‐cone bipolar cells. In contrast, the α3 subunit appears to be predominantly involved with the cone pathways. Thus, expression of different GlyR α subunit genes correlates with anatomically defined connectivities. J. Comp. Neurol. 465:524–539, 2003. © 2003 Wiley‐Liss, Inc.
Hypothalamic orexin (hypocretin) neurons express vesicular glutamate transporters VGLUT1 or VGLUT2
Authors: Rosin Diane L. , Weston Matthew C. , Sevigny Charles P. , Stornetta Ruth L. , Guyenet Patrice G.
Published: September 2003

Initially recognized for their importance in control of appetite, orexins (also called hypocretins) are neuropeptides that are also involved in regulating sleep, arousal, and cardiovascular function. Loss of orexin appears to be the primary cause of narcolepsy. Cells expressing the orexins are restricted to a discrete region of the hypothalamus, but their terminal projections are widely distributed throughout the brain. With the diversity of function and broad distribution of orexin terminals, it is not known whether the orexin cells constitute a homogeneous population. Because orexins produce neuroexcitatory effects, we hypothesized that orexin‐containing neurons are glutamatergic. In the present study we used digoxigenin‐labeled cRNA probes for the vesicular glutamate transporters, VGLUT1 and VGLUT2, for in situ hybridization studies in combination with immunohistochemical detection of orexin cell bodies in the hypothalamus. In general, cells in the hypothalamus expressed low levels of the vesicular glutamate transporters relative to other areas of the forebrain, such as the cortex and thalamus. Light labeling for VGLUT2 mRNA was detected in about 50% of the orexin‐immunoreactive neurons, and a much smaller percentage (≈13%) of orexin‐immunoreactive cells was found to express VGLUT1. Despite the fact that intense labeling for GAD67 mRNA was found in a large number of cells throughout the hypothalamus, none of the orexin‐immunoreactive cells was found to be GABAergic. These findings, showing that many of the orexin neurons are glutamatergic, are consistent with the neuroexcitatory effects of orexin but suggest that another neurochemical phenotype may define the remaining subset of orexin neurons. J. Comp. Neurol. 465:593–603, 2003. © 2003 Wiley‐Liss, Inc.
Experimental study of the connections of the gustatory system in the rainbow trout, Oncorhynchus mykiss
Authors: Folgueira Mónica , Anadón Ramón , Yáñez Julián
Published: September 2003

Salmonids are a group of teleosts with a nonspecialized gustatory system. With the aim of describing the gustatory connections in a member of this group, we carried out tract‐tracing experiments using the lipophilic carbocyanine dye 1,1′‐dioctadecyl 3,3,3′,3′‐tetramethylindocarbocyanine perchlorate (DiI) in fixed brains of the rainbow trout (Oncorhynchus mykiss). The neural tracer was applied to the primary viscerosensory column, secondary gustatory visceral nucleus (SGN), torus lateralis (TL), and tertiary gustatory nucleus (TGN), the dorsal part of the ventral area of the telencephalon (dorsal‐Vv), and the medial area of the dorsal telencephalon (Dm). The primary viscerosensory column projects mainly to the SGN. DiI application to the SGN showed a bilateral and reciprocal connection with the TGN and a rostral portion of the nucleus of the lateral hypothalamic recess. The application of DiI in the dorsal‐Vv and Dm at levels rostral to the anterior commissure led to labeling of a restricted group of diencephalic neurons in the TGN and sending dendrites to the TL. DiI application to the TL/TGN anterogradely labeled fibers that coursed in the medial forebrain bundle innervating the precommissural portion of the dorsal‐Vv and Dm. Caudally, this type of application led to labeling of fibers in the viscerosensory column and perikarya in the SGN. Tract‐tracing results showed direct projections from the diencephalic and rhombencephalic gustatory nuclei to the telencephalon. There was a direct and reciprocal connection between the SGN and the ventral telencephalon. The results showed that the gustatory connections of the trout are similar to those of teleosts, with highly specialized gustatory centers as in cyprinids and ictalurids, and to that observed in the percomorph tilapia, thus demonstrating a basic organization that is shared by most teleosts. J. Comp. Neurol. 465:604–619, 2003. © 2003 Wiley‐Liss, Inc.
New Insights into the Jahn–Teller Effect through ab initio Quantum‐Mechanical/Molecular‐Mechanical Molecular Dynamics Simulations of CuII in Water
Authors: Schwenk Christian F. , Rode Bernd M.
Published: September 2003

The CuII hydration shell structure has been studied by means of classical molecular dynamics (MD) simulations including three‐body corrections and hybrid quantum‐mechanical/molecular‐mechanical (QM/MM) molecular dynamics (MD) simulations at the Hartree–Fock level. The copper(II) ion is found to be six‐fold coordinated and [Cu(H2O)6]2+ exhibits a distorted octahedral structure. The QM/MM MD approach reproduces correctly the experimentally observed Jahn–Teller effect but exhibits faster inversions (<200 fs) and a more complex behaviour than expected from experimental data. The dynamic Jahn–Teller effect causes the high lability of [Cu(H2O)6]2+ with a ligand‐exchange rate constant some orders of magnitude higher than its neighbouring ions NiII and ZnII. Nevertheless, no first‐shell water exchange occurred during a 30‐ps simulation. The structure of the hydrated ion is discussed in terms of radial distribution functions, coordination numbers, and various angular distributions and the dynamical properties as librational and vibrational motions and reorientational times were evaluated, which lead to detailed information about the first hydration shell. Second‐shell water‐exchange processes could be observed within the simulation time scale and yielded a mean ligand residence time of ≈20 ps.
Molecular Spin Clusters: New Synthetic Approaches and Neutron Scattering Studies
Authors: Basler Reto , Boskovic Colette , Chaboussant Grégory , Güdel Hans U. , Murrie Mark , Ochsenbein Stefan T. , Sieber Andreas
Published: September 2003

We review our recent work in the field of molecular spin clusters and single‐molecule magnets, showing how inelastic neutron scattering (INS) can be used to determine magnetic exchange interactions and anisotropy splittings. A general introduction to neutron scattering precedes selected examples, building upon the first determination of exchange coupling in a transition metal complex using INS, through anisotropic exchange in cobalt(II) spin clusters to the determination of exchange interactions in a dodecanuclear nickel(II) wheel. The strength of INS for the accurate determination of anisotropy splittings in single‐molecule magnets is revealed. Not only can one determine the axial zero‐field splitting parameter D, which plays a key role in single‐molecule magnet behavior, but also higher‐order terms important in understanding the quantum tunneling behavior. Finally, we review two of our synthetic approaches towards new single‐molecule magnets based on nickel, manganese, and iron.
Ionic Liquid for in situ Vis/NIR and Raman Spectroelectrochemistry: Doping of Carbon Nanostructures
Authors: Kavan Ladislav , Dunsch Lothar
Published: September 2003

1‐butyl‐3‐methylimidazolium tetrafluoroborate (an ionic liquid) is an advantageous electrolyte for the study of charge‐transfer reactions at single‐walled carbon nanotubes (SWCNTs) and fullerene peapods (C60@SWCNT). Compared to traditional electrolyte solutions, this medium offers a broader window of electrochemical potentials to be applied, and favorable optical properties for in situ Vis/NIR and Raman spectroelectrochemistry of nano‐carbon species. The electrochemistry of both nanotubes and peapods is dominated by their capacitive double‐layer charging. Vis/NIR spectroelectrochemistry confirms the charging‐induced bleaching of transitions between Van Hove singularities. At high positive potentials, new optical transitions were activated in partly filled valence band. The bleaching of optical transitions is mirrored by the quenching of resonance Raman scattering in the region of tube‐related modes. The Raman frequency of the tangential displacement mode of SWCNT shifts to blue upon both anodic and cathodic charging in the ionic liquid. The Raman modes of intratubular C60 exhibit a considerable intensity increase upon anodic doping of peapods.
Long‐Range Transport in an Assembly of ZnO Quantum Dots: The Effects of Quantum Confinement, Coulomb Repulsion and Structural Disorder
Authors: Roest Aarnoud L. , Germeau Alexander , Kelly John J. , Vanmaekelbergh Daniël , Allan Guy , Meulenkamp Eric A.
Published: September 2003

We have studied the storage and long‐range transport of electrons in a porous assembly of weakly coupled ZnO quantum dots permeated with an aqueous and a propylene carbonate electrolyte solution. The number of electrons per ZnO quantum dot is controlled by the electrochemical potential of the assembly; the charge of the electrons is compensated by ions present in the pores. We show with optical and electrical measurements that the injected electrons occupy the S, P, and D type conduction electron levels of the quantum dots; electron storage in surface states is not important. With this method of three‐dimensional charge compensation, up to ten electrons per quantum‐dot can be stored if the assembly is permeated with an aqueous electrolyte. The screening of the electron charge is less effective in the case of an assembly permeated with a propylene carbonate electrolyte solution. Long‐range electron transport is studied with a transistor set‐up. In the case of ZnO assemblies permeated with an aqueous electrolyte, two quantum regimes are observed corresponding to multiple tunnelling between the S orbitals (at a low occupation) and P orbitals (at a higher occupation). In a ZnO quantum‐dot assembly permeated with a propylene carbonate electrolyte solution, there is a strong overlap between these two regimes.
Crosslinked Copolyimide Membranes for Phenol Recovery from Process Water by Pervaporation
Authors: Pithan Frankie , Staudt‐Bickel Claudia
Published: September 2003

The effectiveness of different copolyimide membranes in the process of recovering phenol from water by pervaporation has been investigated. The polyimides were obtained by the polycondensation of 6FDA (4,4′‐hexafluoro‐isopropylidene diphthalic anhydride) with different diamines. The diamines 4MPD (2,3,5,6‐tetramethyl‐1,4‐phenylene diamine), 6FpDA (4,4′‐hexafluoro‐isopropylidene dianiline), 6FpODA (4,4′‐bis‐(4′‐aminophenoxyphenyl)hexafluoropropane), and DABA (3,5‐diaminobenzoic acid) as a monomer providing a crosslinkable group, were used. In order to reach chemical stability at high phenol concentrations, the polymer structures were crosslinked with 1,10‐decanediol and OFHD (2,2,3,3,4,4,5,5‐octafluorohexanediol). Pervaporation experiments were performed at 60 °C, covering a concentration range of phenol between 2 and 11 wt. %. The best separation characteristics were obtained with a 6FDA‐6FpDA/DABA 2:1 membrane crosslinked with 1,10‐decanediol. Using a 7.8 wt. % phenol feed mixture, a total flux of 14 kg μm m−2 h−1 was reached with an enrichment of 40 wt. % phenol in the permeate. It was found that conditioning the membrane using high phenol concentrations (between 8 and 11 wt. %) is a necessary pretreatment in order to enhance the flux and improve enrichment, especially if process water with low phenol concentrations is to be treated. In addition to the experimental results, a comparison with rubbery membrane materials is presented in the discussion.
Electrochemical Studies of Vitamin K1Microdroplets: Electrocatalytic Hydrogen Evolution
Authors: Wain Andrew J. , Wadhawan Jay D. , Compton Richard G.
Published: September 2003

The voltammetry of a basal‐plane pyrolytic graphite electrode modified with a random ensemble of unsupported microdroplets of vitamin K1is investigated when the electrode is immersed in aqueous electrolytes. It is shown that in dilute acidic solutions, electroreduction occurs in a single two‐electron two‐proton process to yield the corresponding hydroquinone at the electrode|vitamin K1microdroplet|aqueous‐electrolyte three‐phase boundary. On addition of ionic alkali‐metal salts to the aqueous acidic phase, the electrochemical reduction of vitamin K1to the quinol is accompanied by catalytic hydrogen evolution within and alkali‐metal‐cation insertion into the organic microdroplets. In strongly alkaline solutions, electrochemical reduction of vitamin K1at the triple‐phase junction is proposed as being a single two‐electron process with concomitant uptake of alkali‐metal cations in order to maintain electroneutrality within the oil phase. Surprisingly, the relative ease of cation insertion into the oil phase is demonstrated to be governed by the degree of ion‐pair formation rather than by the Gibbs transfer energy of the cation across the liquid|liquid interface.
FDTD analysis of dual frequency printed dipole antenna
Authors: Michishita Naobumi , Arai Hiroyuki , Tsunekawa Koichi , Karikomi Masahiro
Published: September 2003

The operating principle of a balun for feeding a printed dipole antenna for base stations of mobile communications is analyzed by the FDTD method. The parameters of the open stub connected in series to the dipole antenna and the shorting stub connected in parallel are studied in detail. It is shown that these two stubs realize dual resonances. The controllable range of the dual resonant frequencies is presented for varying stub lengths. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(10): 9–16, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10184
A spatiotemporal equalization method with cascade configuration of an adaptive antenna array and a decision feedback equalizer
Authors: Hayashi Kazunori , Hara Shinsuke
Published: September 2003

Spatiotemporal equalization is a technique to compensate the intersymbol interference (ISI) due to multipath effects by means of information about the received signal on both the time axis and the spatial axis. In this paper, an application of the spatiotemporal equalizer to high‐speed wireless communications such as wireless LAN is considered. In order to reduce the total number of weights, a spatiotemporal equalizer using a cascade connection of an adaptive array and a decision feedback equalizer (DFE) is examined. Since the error characteristic surface in the minimum mean square error (MMSE) criterion weight calculation for the spatiotemporal equalizer with a cascade configuration is a fourth‐order function of the weight, there is a possibility of encountering a local minimum in addition to the global minimum. In this paper, in order to prevent the weights from falling into a local minimum, the weights of the adaptive array and the DFE are computed individually in two steps. In addition, a captured path is selected adaptively by means of an adaptive array based on the estimated complex instantaneous impulse response of the propagation path. In this way, the proposed spatiotemporal equalization method can handle various propagation paths. The characteristics of the method are evaluated by computer simulation. It is confirmed that the proposed method exhibits excellent characteristics with few weights in various propagation environments. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(10): 25–35, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10186