bluuebunny/crossref_metadata_2025 huggingface dataset:
A Simple Method for Synthesizing Copper Nanotube Arrays
Authors: Wang Yinhai , Ye Changhui , Fang Xiaosheng , Zhang Lide
Published: January 2004

A simple method to synthesize copper nanotubes in alumina membrane using the direct electrochemical deposition technique is presented. The method does not need a molecular anchor to treat the membrane in synthesizing the nanotubes. The diameter of the synthesized copper nanotubes is about 40 nm and depends on the pore size of the alumina membrane.
Fluorescence Spectra of 6-Substituted 2,3-Dicyano-5-[4-(diethylamino)styryl]-7-methyl-6H-1,4-diazepines in Solid State
Authors: Horiguchi Emi , Matsumoto Shinya , Funabiki Kazumasa , Matsui Masaki
Published: January 2004

Intense fluorescence of 2,3-dicyano-5-[4-(diethylamino)styryl]-7-methyl-6H-1,4-diazepines in solid state could be successful in improving interference in cofacial molecular stacking between the chromophores by the bulky 6-substituent.
The Timing of Repeat Purchases of Consumer Durable Goods: The Role of Functional Bases of Consumer Attitudes
Authors: Grewal Rajdeep , Mehta Raj , Kardes Frank R.
Published: January 2004

In an attempt to bring consumer psychology theories into research on the timing of repurchase of consumer durables, the authors suggest that attitude functions (knowledge, value expressive, social adjustive, and utilitarian) can help explain and predict interpurchase intervals. Adopting an interactionist perspective, the authors propose that the effect of the attitude functions is contingent on contextual factors, which they theorize as the nature of the product (along public-private and luxury-necessity dimensions) and the nature of the decision (forced or unforced purchase decision). Hypothesis testing is facilitated by survey data on actual purchase decisions and hazard models that incorporate individual heterogeneity. The results support the suggested role of attitude functions in explaining and predicting interpurchase intervals and suggest means by which managers can position their products to shorten interpurchase intervals.
Using Combined-Currency Prices to Lower Consumers’ Perceived Cost
Authors: Drèze Xavier , Nunes Joseph C.
Published: January 2004

The increasing popularity of loyalty programs and related marketing promotions has resulted in the introduction of several new currencies (e.g., frequent flier miles, Diner's Club “Club Rewards”) that consumers accumulate, budget, save, and spend much as they do traditional paper money. As consumers are increasingly able to pay for goods and services such as airline travel, hotel stays, and groceries in various combinations of currencies, an understanding of how shoppers respond to “combined-currency pricing” is important for marketers. This research is the first to explore how consumers evaluate transactions that involve combined-currency prices, or prices issued in multiple currencies (e.g., $39 and 16,000 miles). The authors present a formal mathematical proof that outlines the conditions under which a price that comprises payments delivered in different currencies can be superior to a standard, single-currency price, either by lowering the psychological or perceived cost associated with a particular revenue objective (i.e., price) or by raising the amount of revenue collected given a particular perceived cost. Three studies, in which respondents evaluate and choose among prices issued in single and combined currencies, offer both experimental and empirical support.
A Direct Approach to Predicting Discretized Response in Target Marketing
Authors: Bodapati Anand , Gupta Sachin
Published: January 2004

A problem that occurs frequently in direct marketing is the prediction of the value of a discretizing function of a response variable. For example, to target consumers for a coupon mailing, a retail chain may want to predict whether a prospective customer's grocery expenditures exceed a predetermined threshold. The current approach to this prediction problem is to model the response variable and then apply the discretizing function to the predicted value of the response variable. In contrast with this “indirect” approach, the authors propose a “direct” approach in which they model discretized values of the response variable. They show theoretically that the direct approach achieves better predictive performance than the commonly used indirect approach when the response model is misspecified and the sample size is large. These two conditions are commonly met in direct marketing situations. This result is counterintuitive because the direct approach entails “throwing away” information. However, although both the discretized response data and the continuous data provide biased predictions when a misspecified model is used, the lower information content of the discretized variable helps the bias be smaller. The authors demonstrate the performance of the proposed approach in a simulation experiment, a retail targeting application, and a customer satisfaction application. The key managerial implication of the result is that the current practice of restricting attention to models based on the indirect approach may be suboptimal. Target marketers should expand the set of candidate models to include models based on the proposed direct approach.
Performance of Store Brands: A Cross-Country Analysis of Consumer Store-Brand Preferences, Perceptions, and Risk
Authors: Erdem Tülin , Zhao Ying , Valenzuela Ana
Published: January 2004

This article empirically studies consumer choice behavior with respect to store brands in the United States, the United Kingdom, and Spain. Store-brand market shares differ by country and are usually much higher in Europe than in the United States. The authors study the notion that the differential success of store brands in the United States and Europe is the higher brand equity that store brands command in Europe than in the United States. They use a framework based on consumer brand choice under uncertainty and brands as signals of product positions to conduct their analysis. More specifically, they examine whether uncertainty about quality (or the positioning of the brand in the product space); perceived quality of store brands versus national brands; consistency in store-brand offerings over time; and consumer attitudes toward risk, quality, and price underlie the differential success of store brands at least partially in the United States and Europe. The authors’ model is estimated on scanner-panel data on laundry detergent in the U.S., U.K., and Spanish markets and on toilet paper and margarine data in the U.S. and Spanish markets. The authors find that consumer learning and perceived risk (and associated brand equity), as well as consumer attitude toward risk, quality, and price, play an important role in consumers’ store-brand and national-brand choices and contribute to the differences in relative success of store brands across the countries studied.
The Effects of Vesicular Volume on Secretion through the Fusion Pore in Exocytotic Release from PC12 Cells
Authors: Sombers L. A. , Hanchar H. J. , Colliver T. L. , Wittenberg N. , Cans A. , Arbault S. , Amatore C. , Ewing A. G.
Published: January 2004

Many spikes in amperometric records of exocytosis events initially exhibit a prespike feature, or foot, which represents a steady-state flux of neurotransmitter through a stable fusion pore spanning both the vesicle and plasma membranes and connecting the vesicle lumen to the extracellular fluid. Here, we present the first evidence indicating that vesicular volume before secretion is strongly correlated with the characteristics of amperometric foot events.l-3,4-Dihydroxyphenylalanine and reserpine have been used to increase and decrease, respectively, the volume of single pheochromocytoma cell vesicles. Amperometry and transmission electron microscopy have been used to determine that as vesicle size is decreased the frequency with which foot events are observed increases, the amount and duration of neurotransmitter released in the foot portion of the event decreases, and vesicles release a greater percentage of their total contents in the foot portion of the event. This previously unidentified correlation provides new insight into how vesicle volume can modulate the activity of the exocytotic fusion pore.
Odorant Receptor Expression Patterns Are Restored in Lesion-Recovered Rat Olfactory Epithelium
Authors: Iwema Carrie L. , Fang Hengsheng , Kurtz Daniel B. , Youngentob Steven L. , Schwob James E.
Published: January 2004

Lesions of the olfactory periphery provide a means for examining the reconstitution of a diverse and highly regulated population of sensory neurons and the growth,en masse, of nascent axons to the bulb. The olfactory epithelium and its projection onto the bulb are reconstituted after ablation by methyl bromide gas, and some measure of olfactory function is restored. The extent to which the system regenerates the full repertoire of odorant receptor-expressing neurons, particularly their spatially restricted distribution across the epithelial sheet, is unknown, however, and altered odorant receptor expression might contribute to the persistent distortion of odorant quality that is observed in the lesioned-recovered animals. To address the question of receptor expression in the recovered epithelium, we performedin situhybridization with digoxigenin-labeled riboprobes for eight odorant receptors on the olfactory epithelium from unilaterally methyl bromide-lesioned and control rats. The data demonstrate that the distribution of sensory neuron types, as identified and defined by odorant receptor expression, is restored to normal or nearly so by 3 months after lesion. Likewise, the numbers of probe-labeled neurons in the lesioned-recovered epithelium are nearly equivalent to the unlesioned side at this time. Finally, our evidence suggests that odorant receptors are distributed in multiple overlapping bands in the normal, unlesioned, and lesioned-recovered epithelium rather than in the conventionally accepted three or four zones. Thus, the primary sensory elements required for functional recovery of the olfactory system after damage are restored, and altered function implies the persistence of a more central failure in regeneration.
Attenuated Response to Stress and Novelty and Hypersensitivity to Seizures in 5-HT4Receptor Knock-Out Mice
Authors: Compan Valérie , Zhou Mingming , Grailhe Régis , Gazzara Russell A. , Martin Renee , Gingrich Jay , Dumuis Aline , Brunner Daniela , Bockaert Joël , Hen René
Published: January 2004

To study the functions of 5-HT4receptors, a null mutation was engineered in the corresponding gene. 5-HT4receptor knock-out mice displayed normal feeding and motor behaviors in baseline conditions but abnormal feeding and locomotor behavior in response to stress and novelty. Specifically, stress-induced hypophagia and novelty-induced exploratory activity were attenuated in the knock-out mice. In addition, pentylenetetrazol-induced convulsive responses were enhanced in the knock-out mice, suggesting an increase in neuronal network excitability. These results provide the first example of a genetic deficit that disrupts the ability of stress to reduce feeding and body weight and suggest that 5-HT4receptors may be involved in stress-induced anorexia and seizure susceptibility.
Limited Role of Developmental Programmed Cell Death Pathways inDrosophila norpARetinal Degeneration
Authors: Hsu Cheng-Da , Whaley Michelle A. , Frazer Kristin , Miller Douglas A. , Mitchell Kathleen A. , Adams Sheila M. , O'Tousa Joseph E.
Published: January 2004

We examined the role of programmed cell death (PCD) pathways in retinal degeneration caused by a mutation in thenorpAgene.norpAdegeneration shows morphological hallmarks of programmed cell death, specifically cytoplasmic condensation and engulfment of the dying photoreceptor cells by neighboring retinal pigment cells. However, genetic mosaic analysis of adult photoreceptors lackingrpr, hid, andgrimshow that these PCD inducers are not required fornorpAdegeneration. We showed previously that ectopic expression of eitherrprorhidtriggers rapid PCD in adult photoreceptors, and this is completely suppressed by the coexpression of the baculoviral P35 caspase inhibitor. In contrast, expression of P35 does not suppressnorpAretinal degeneration, although a small delay in the rate of degeneration is observed in low light-low temperature conditions. P35 does not alter the morphological characteristics ofnorpAcell death. Overexpression of theDrosophilainhibitor of apoptosis Diap1 or a dominant-negative form of the Dronc caspase, even when coexpressed with P35, does not dramatically alter the time course ofnorpAdegeneration. These results establish that the pathways responsible for PCD in development do not play a major role in adult retinal degeneration caused bynorpA.
Small Clusters of Electrically Coupled Neurons Generate Synchronous Rhythms in the Thalamic Reticular Nucleus
Authors: Long Michael A. , Landisman Carole E. , Connors Barry W.
Published: January 2004

The inhibitory neurons of the thalamic reticular nucleus (TRN) contribute to the generation of widespread oscillations in the thalamocortical system. Some TRN neurons are interconnected by electrical synapses, and here we tested the possibility that electrical synapses mediate rhythmic synchrony in juvenile rats. Both the incidence and strength of electrical coupling between pairs of TRN neurons were a steep function of intersomatic distance, and coupling was absent at distances >40 μm. Presynaptic spike bursts evoked much larger electrical postsynaptic potentials than did single presynaptic spikes. Activation of metabotropic glutamate receptors (mGluRs) with a bath-applied agonist or an endogenous ligand released during tetanic stimulation induced robust rhythms of the subthreshold membrane potential, with a mean frequency of ∼10 Hz. In the absence of fast chemical synaptic transmission, subthreshold rhythms and the action potentials that they evoked were well synchronized between closely spaced, electrically coupled pairs; rhythms in noncoupled cells were not synchronized. The results suggest that electrical synapses can coordinate spindle-frequency rhythms among small clusters of mGluR-activated TRN cells.
Learning Modulation of Odor-Induced Oscillatory Responses in the Rat Olfactory Bulb: A Correlate of Odor Recognition?
Authors: Martin Claire , Gervais Rémi , Hugues Etienne , Messaoudi Belkacem , Ravel Nadine
Published: January 2004

In the first relay of information processing, the olfactory bulb (OB), odors are known to generate specific spatial patterns of activity. Recently, in freely behaving rats, we demonstrated that learning modulated oscillatory activity in local field potential (LFP), in response to odors, in both β (15-40 Hz) and γ (60-90 Hz) bands. The present study further characterized this odor-induced oscillatory activity with emphasis on its spatiotemporal distribution over the olfactory bulb and on its relationship with improvement of behavioral performances along training. For that purpose, LFPs were simultaneously recorded from four locations in the OB in freely moving rats performing an olfactory discrimination task. Electrodes were chronically implanted near relay neurons in the mitral cell body layer. Time-frequency methods were used to extract signal characteristics (amplitude, frequency, and time course) in the two frequency bands. Before training, odor presentation produced, on each site, a power decrease in γ oscillations and a weak but significant increase in power of β oscillations (∼25 Hz). When the training was achieved, these two phenomena were amplified. Interestingly, the β oscillatory response showed several significant differences between the anterodorsal and posteroventral regions of the OB. In addition, clear-cut β responses occurred in the signal as soon as animals began to master the task. As a whole, our results point to the possible functional importance of β oscillatory activity in the mammalian OB, particularly in the context of olfactory learning.
Sodium Channels and Dendritic Spike Initiation at Excitatory Synapses in Globus Pallidus Neurons
Authors: Hanson Jesse E. , Smith Yoland , Jaeger Dieter
Published: January 2004

Glutamatergic inputs from the subthalamic nucleus are suspected to provide a prominent source of excitation to globus pallidus (GP) neurons, despite their scarce number and mainly distal dendritic location. In this study we address the issue of whether dendritic sodium channels may facilitate the effect of excitatory inputs in GP. First, we examined the subcellular distribution of sodium channels using electron microscopic observations of immunoperoxidase and immunogold labeling. Voltage-gated sodium channels were found throughout GP dendrites and furthermore exhibited a specific clustering at sites of excitatory synaptic inputs. To examine the possibility that these channels could mediate dendritic spike generation, synaptic stimulation at visualized dendritic sites was performed during whole-cell recordingsin vitro. These recordings revealed dendritic spike initiation in response to small excitatory inputs even for very distal stimulation sites. In contrast, subthreshold responses were mostly or fully attenuated at the soma for stimulation sites on distal dendrites. Computer simulations support the hypothesis that postsynaptic clustering of sodium channels allows dendritic triggering of spikes in response to inputs that would be too small to trigger a spike given uniformly distributed dendritic sodium channels. These findings indicate that postsynaptic sodium channel clustering is an effective mechanism to mediate a novel form of synaptic amplification and dendritic spike initiation. The ability of small amounts of excitation to trigger spikes in GP dendrites supports the prominent role of subthalamic input in the control of GP activity.
Serotonin Enhances the Resistance Reflex of the Locomotor Network of the Crayfish through Multiple Modulatory Effects that Act Cooperatively
Authors: Le Bon-Jego Morgane , Cattaert Daniel , Pearlstein Edouard
Published: January 2004

Serotonin (5HT) is an endogenous amine that modifies posture in crustacea. Here, we examined the mechanisms of action of 5HT on the resistance reflex in crayfish legs. This reflex, which counteracts movements imposed on a limb, is based on a negative feedback system formed by proprioceptors that sense joint angle movements and activate opposing motoneurons. We performed intracellular recordings from depressor motoneurons while repetitively stretching and releasing a leg joint proprioceptor in a restingin vitropreparation (i.e., a preparation that lacks spontaneous rhythmic activity). 5HT increased the amplitude of the depolarization during the release phase of the proprioceptor (corresponding to an upward movement of the leg) and the discharge frequency of the motoneurons. The 5HT-induced increase in the resistance reflex is caused, to a large extent, by polysynaptic pathways because it was very attenuated in the presence of high divalent cation solution. In addition to this activation of the polysynaptic pathways, 5HT also has postsynaptic effects that enhance the resistance reflex. 5HT causes a tonic depolarization, as well as an increase in the time constant and input resistance of motoneurons. We developed a simple mathematical model to describe the integrative properties of the motoneurons. The conclusion of this study is that the input frequency and the decay time constant of the EPSPs interact in such a way that small simultaneous changes in these parameters can cause a large effect on summation. Therefore, the conjunction of presynaptic and postsynaptic changes produces a strong cooperative effect on the resistance reflex response.
β-Amyloid Peptides Induce Mitochondrial Dysfunction and Oxidative Stress in Astrocytes and Death of Neurons through Activation of NADPH Oxidase
Authors: Abramov Andrey Y. , Canevari Laura , Duchen Michael R.
Published: January 2004

β-Amyloid (βA) peptide is strongly implicated in the neurodegeneration underlying Alzheimer's disease, but the mechanisms of neurotoxicity remain controversial. This study establishes a central role for oxidative stress by the activation of NADPH oxidase in astrocytes as the cause of βA-induced neuronal death. βA causes a loss of mitochondrial potential in astrocytes but not in neurons. The mitochondrial response consists of Ca2+-dependent transient depolarizations superimposed on a slow collapse of potential. The slow response is both prevented by antioxidants and, remarkably, reversed by provision of glutamate and other mitochondrial substrates to complexes I and II. These findings suggest that the depolarization reflects oxidative damage to metabolic pathways upstream of mitochondrial respiration. Inhibition of NADPH oxidase by diphenylene iodonium or 4-hydroxy-3-methoxy-acetophenone blocks βA-induced reactive oxygen species generation, prevents the mitochondrial depolarization, prevents βA-induced glutathione depletion in both neurons and astrocytes, and protects neurons from cell death, placing the astrocyte NADPH oxidase as a primary target of βA-induced neurodegeneration.
Discrimination of Voiced Stop Consonants Based on Auditory Nerve Discharges
Authors: Bandyopadhyay Sharba , Young Eric D.
Published: January 2004

Previous studies of the neural representation of speech assumed some form of neural code, usually discharge rate or phase locking, for the representation. In the present study, responses to five synthesized CVC_CV (e.g., /dad_da/) utterances have been examined using information-theoretic distance measures [or Kullback-Leibler (KL) distance] that are independent of a priori assumptions about the neural code. The consonants in the stimuli fall along a continuum from /b/ to /d/ and include both formant-frequency (F1, F2, and F3) transitions and onset (release) bursts. Differences in responses to pairs of stimuli, based on single-fiber auditory nerve responses at 70 and 50 dB sound pressure level, have been quantified, based on KL and KL-like distances, to show how each portion of the response contributes to information coding and the fidelity of the encoding. Distances were large at best frequencies, in which the formants differ but were largest for fibers encoding the high-frequency release bursts. Distances computed at differing time resolutions show significant information in the temporal pattern of spiking, beyond that encoded by rate, at time resolutions from 1-40 msec. Single-fiber just noticeable differences (JNDs) for F2 and F3 were computed from the data. These results show that F2 is coded with greater fidelity than F3, even among fibers tuned to F3, and that JNDs are larger in the syllable final consonant than in the releases.
Suppression of p75NTR Does Not Promote Regeneration of Injured Spinal Cord in Mice
Authors: Song Xing-Yun , Zhong Jin-hua , Wang Xin , Zhou Xin-Fu
Published: January 2004

The neurotrophin receptor p75NTR is the coreceptor for Nogo receptor, mediating growth cone collapsein vitroby MAG, myelin oligodendrocyte glycoprotein (Omgp), and Nogo. Whether p75NTR plays any role in the failure of nerve regenerationin vivois not known. Immunohistochemical data showed that p75NTR was expressed in only a very small subset of ascending sensory axons but not in any corticospinal axons in the dorsal column of either normal or injured spinal cord. Using p75NTR-deficient mice, we showed that the depletion of the functional p75NTR did not promote the regeneration of the descending corticospinal tract and ascending sensory neurons in the spinal cord 2 weeks after spinal cord injury. Local administration of p75NTR-Fc fusion molecule, the dominant-negative receptor to block the function of neurite outgrowth inhibitors, did not improve regeneration of ascending sensory neurons in the injured spinal cord. Our results suggest that p75NTR may not be a critical molecule mediating the function of myelin-associated inhibitory factorsin vivo.
Semaphorin3D Guides Retinal Axons along the Dorsoventral Axis of the Tectum
Authors: Liu Yan , Berndt Jason , Su Fengyun , Tawarayama Hiroshi , Shoji Wataru , Kuwada John Y. , Halloran Mary C.
Published: January 2004

We examined the role of Sema3D, a semaphorin of previously unknown function, in guiding retinal ganglion cell (RGC) axons to the optic tectum in the developing zebrafish. Sema3D is expressed more strongly in the ventral versus dorsal tectum, suggesting that it may participate in guiding RGC axons along the dorsoventral axis of the tectum. Ubiquitous misexpression of Sema3D in transgenic zebrafish inhibits ventral but not dorsal RGC axon growth. In addition, ventral RGC axons avoid or stop at individual cells misexpressing Sema3D along their pathway. Sema3D ubiquitous misexpression at later stages also causes ventral RGC axon arbors to spread more widely along the dorsoventral axis of the tectum. Knock-down of Sema3D with morpholino antisense causes ventral RGC axons to extend aberrantly into the ventral tectum. These results suggest that Sema3D in the ventral tectum normally acts to inhibit ventral RGCs from extending into ventral tectum, ensuring their correct innervation of dorsal tectum.
Long-Term Potentiation in an Avian Basal Ganglia Nucleus Essential for Vocal Learning
Authors: Ding Long , Perkel David J.
Published: January 2004

Vocal learning in songbirds provides an excellent model for sensorimotor learning in vertebrates, with an accessible, well-defined behavior and discrete neural substrate. The rich behavioral plasticity exhibited by songbirds, however, contrasts starkly with the scarcity of candidate cellular mechanisms. Here, we report for the first time on an activity-dependent form of synaptic plasticity in area X, a component of the song system required for song learning and song maintenance. In slice preparations of zebra finch area X, pairing of high-frequency presynaptic stimulation with postsynaptic depolarization induces Hebbian long-term potentiation (LTP) of the glutamatergic inputs to spiny neurons. This form of LTP requires activation of NMDA receptors and D1-like dopamine receptors. In addition, LTP is observed in birds as young as 47 d after hatching and also in adult birds but not in younger birds, providing evidence of developmental regulation of the onset of synaptic plasticity. These properties make this form of LTP the best known candidate mechanism for reinforcement-based vocal learning in juveniles and song maintenance in adult birds.
Competition between Phasic and Asynchronous Release for Recovered Synaptic Vesicles at Developing Hippocampal Autaptic Synapses
Authors: Otsu Yo , Shahrezaei Vahid , Li Bo , Raymond Lynn A. , Delaney Kerry R. , Murphy Timothy H.
Published: January 2004

Developing hippocampal neurons in microisland culture undergo rapid and extensive transmitter release-dependent depression of evoked (phasic) excitatory synaptic activity in response to 1 sec trains of 20 Hz stimulation. Although evoked phasic release was attenuated by repeated stimuli, asynchronous (miniature like) release continued at a high rate equivalent to ∼2.8 readily releasable pools (RRPs) of quanta/sec. Asynchronous release reflected the recovery and immediate release of quanta because it was resistant to sucrose-induced depletion of the RRP. Asynchronous and phasic release appeared to compete for a common limited supply of release-ready quanta because agents that block asynchronous release, such as EGTA-AM, led to enhanced steady-state phasic release, whereas prolongation of the asynchronous release time course by LiCl delayed recovery of phasic release from depression. Modeling suggested that the resistance of asynchronous release to depression was associated with its ability to out-compete phasic release for recovered quanta attributable to its relatively low release rate (up to 0.04/msec per vesicle) stimulated by bulk intracellular Ca2+concentration ([Ca2+]i) that could function over prolonged intervals between successive stimuli. Although phasic release was associated with a considerably higher peak rate of release (0.4/msec per vesicle), the [Ca2+]imicrodomains that trigger it are brief (1 msec), and with asynchronous release present, relatively few quanta can accumulate within the RRP to be available for phasic release. We conclude that despite depression of phasic release during train stimulation, transmission can be maintained at a near-maximal rate by switching to an asynchronous mode that takes advantage of a bulk presynaptic [Ca2+]i.
Androgens Increase Spine Synapse Density in the CA1 Hippocampal Subfield of Ovariectomized Female Rats
Authors: Leranth Csaba , Hajszan Tibor , MacLusky Neil J.
Published: January 2004

The effects of androgen on the density of spine synapses on pyramidal neurons in the CA1 area of the hippocampus were studied in ovariectomized (OVX) adult female rats. Treatment of OVX rats with testosterone propionate (TP; 500 μg/d, s.c., 2 d) significantly increased spine synapse density (from 0.661 ± 0.016 spine synapse/μm3in OVX rats to 1.081 ± 0.018 spine synapse/μm3after TP treatment). A smaller, but still statistically significant, increase in synapse density (0.955 ± 0.029 spine synapse/μm3) was observed in OVX animals after treatment with the nonaromatizable androgen dihydrotestosterone (DHT; 500 μg/d, s.c., 2 d). Administration of 1 mg of letrozole, a powerful nonsteroidal aromatase inhibitor, 1 hr before the steroid injections almost completely blocked the synaptic response to testosterone, resulting in a mean synapse density (0.723 ± 0.003 spine synapse/μm3) only slightly higher than in OVX control rats. By contrast, the response to DHT was unaffected by letrozole pretreatment. These data suggest that androgen secretion during the female reproductive cycle may contribute to cyclical changes in hippocampal synaptic density. They also indicate that androgen treatment may be as effective as estrogen replacement in reversing the decline in hippocampal CA1 spine synapses that follows loss of ovarian function. Induction of hippocampal synapse formation by androgen is not mediated entirely via intracerebral estrogen biosynthesis, however, because aromatase-independent mechanisms also significantly affect CA1 spine synapse density.
Control of Cortical Neuron Migration and Layering: Cell and Non Cell-Autonomous Effects of p35
Authors: Hammond Vicki , Tsai Li-Huei , Tan Seong-Seng
Published: January 2004

The migration, arrest, and ultimately positioning of cortical neurons require signaling activity from Reelin as well as from cyclin-dependent kinase 5 (Cdk5). Although both molecules control neuronal positioning, they achieve their effects by quite separate molecular pathways. Cdk5 is a serine-threonine kinase, the activity of which is dependent on its activating subunits p35 and p39. Mice deficient in Cdk5, p35, or both p35 and p39 display the hallmarks of disturbed cortical development, including cortical layer inversion, neuronal disorientation, and abnormal fiber infiltration. To distinguish between the cell- and non cell-autonomous functions of p35, we constructedp35+/+↔p35-/-chimeras using thelacZgene as an independent marker forp35+/+cells. In this shared developmental space, wild-type and mutant neurons behaved cell-autonomously with respect to layering. Wild-type cells formed a properly layered supercortex that is mirrored by an inverted mutant cortex lying underneath. However, this genotype-specific behavior was confined to the pyramidal population, and interneurons belonging to either genotype were indiscriminately distributed. However, there was also non cell-autonomous rescue of mutant neurons, and this rescue was specific only to early-born pyramidal neurons belonging to layer V. Rescued neurons reached the correct layer address and possessed appropriate neuronal morphology, orientation, and projections. Later-born neurons belonging to layers II and III were not rescued. These results demonstrate that p35 signaling can have both cell- and non cell-autonomous consequences, and their effects are not uniformly shared by cortical neurons born at different times or born at different places (projection neurons vs interneurons).
Reasons for high food prices in small market areas: The case of the Åland Islands
Authors: Aalto‐Setälä Ville , Kinnunen Jouko , Koistinen Katri
Published: January 2004

This article considers the reasons for high grocery prices in a small isolated market. The starting point of our study is the knowledge that the price of food in the Åland Islands—a small archipelago between Finland and Sweden—is significantly higher than in continental Finland. We also know that store‐level economies of scale in grocery retailing mean that the structure of a small market is, even in the best case, either inefficient or uncompetitive. The article compares the price level of stores in Åland and Finland. Our aim is to decompose the price differences and allocate them between their various causes. The empirical results of the study are in accordance with the theory: high prices in Åland arise from a small average store size, high concentration in both the retailing and the food processing sector, border taxes, and transportation costs. An additional source of high prices is the strong regional spirit of the Ålanders: they are prepared to pay higher prices for products that are made in Åland. [JEL citations: D430, L110, L810]. © 2004 Wiley Periodicals, Inc. Agribusiness 20: 17–29, 2004.
Delaware farmers' adoption of GE soybeans in a time of uncertain U.S. adoption
Authors: Bernard John C. , Pesek, Jr. John D. , Fan Chunbo
Published: January 2004

Soybeans genetically engineered to withstand the herbicide Roundup became available to farmers in 1996 and rapidly became the most popular of the new biotechnology crops. However, rising concerns over consumer acceptance late in 1999 created a climate of uncertainty over national markets and put continuing adoption in question. This study models Delaware farmers' adoption patterns and decisions, and examines accompanying changes in their operations at the start of the 2000 season. Model results show adoption to have continued upward in terms of farmers and acreage, with age, soybean income, computer use, and labeling opinion identifying major adopters. Adopters were expanding operations and utilizing accompanying new techniques at a high rate. With much of the state farmers' market assured by the local broiler industry, farmers appeared unconcerned over national market uncertainties. The research thus demonstrates the need to consider local conditions and potential for variations in adoption patterns and adopter characteristics. [EconLit citations: Q160, O330]. © 2004 Wiley Periodicals, Inc. Agribusiness 20: 81–94, 2004.
Attitudes towards the use of GMOs in food production and their impact on buying intention: The role of positive sensory experience
Authors: Grunert Klaus G. , Bech‐Larsen Tino , Lähteenmäki Liisa , Ueland Øydis , Åström Annika
Published: January 2004

European consumers are skeptical towards genetically modified organisms (GMOs) in food production, and their willingness to buy such products is low. Previous research also shows that these attitudes are quite resistant to attempts to change them by giving additional information. The aim of the study was to investigate if positive sensory experience with a (purportedly) GMO‐based food product would influence consumers' attitude towards the use of GMOs in food production. An experiment was conducted in which subjects in the experimental group tasted cheeses, one of which was labeled as “produced using GMOs.” The cheeses were selected in a way that ensured that the subject had a sensory preference for the GMO cheese. A control group tasted cheeses that were unlabelled. After the tasting, subjects completed a conjoint analysis task about cheese, in which the type of starter culture used (GMO/conventional) was one of the attributes. Subjects also were administered a set of items measuring attitude towards the use of GMOs in food production. Results showed that for subjects in the experimental group (who believed that they had tasted a GMO cheese, with which they had a positive sensory experience) (1) attitude towards GMO in food production was less negative, and (2) type of starter culture used (GM/conventional) had less impact on their buying intentions with regard to cheese than for subjects in the control group. [EconLit citations: L660, M310, Q130]. © 2004 Wiley Periodicals, Inc. Agribusiness 20: 95–107, 2004.
Effects of different kinds of cranial deformation on the incidence of wormian bones
Authors: O'Loughlin Valerie Dean
Published: January 2004

Researchers have debated whether the presence and frequency of wormian bones (sutural bones, supernumerary bones, and ossicles) are attributable to genetic factors, environmental factors, or both. This research examines the effects of many different kinds of cranial deformation on the incidence of wormian bones. A sample of 127 deformed and undeformed crania from New World archaeological sites was examined. An undeformed cranial sample (n = 35) was compared to the following cranially deformed groups: 1) occipital, 2) lambdoid, 3) annular, 4) fronto‐vertico‐occipital, 5) parallelo‐fronto‐occipital, and 6) sagittal synostosis. Three levels of degree of cultural cranial deformation were qualitatively determined. Type and number of wormian bones along each major suture were recorded for each cranium. Group means were analyzed using Kruskal‐Wallis one‐way ANOVA statistical tests to test the null hypothesis that cranial deformation does not have an effect on wormian bone incidence. Results indicate that all forms of cranial deformation affect the frequency of some types of wormian bones. In particular, all cranially deformed groups exhibited significantly greater frequencies of lambdoid ossicles. Apical, parieto‐mastoid, and occipito‐mastoid wormian bones also appeared with greater frequency in some groups of culturally deformed crania. Further, varying degrees of cultural deformation all had more lambdoid wormian bones than the undeformed group. These results suggest that wormian bone development in posteriorly placed sutures may be affected more by environmental forces than are their anteriorly placed counterparts. Am J Phys Anthropol, 2003. © 2003 Wiley‐Liss, Inc.
Multivariate analysis of organismal and habitat parameters in two neotropical primate communities
Authors: Youlatos Dionisios
Published: January 2004

This paper investigates the interrelations of some organismal and habitat parameters in two platyrrhine primate communities in French Guiana and Ecuadorian Amazonia. Fifteen habitat and organismal parameters and body weight were retained after a preliminary analysis, on the basis of frequent use and constraints reflected in anatomical specializations. The 16 parameters for 13 platyrrhine species were used for a series of principal components analyses (PCAs). All PCAs on separate or combined communities provided comparable results. The Atelinae,Ateles,Alouatta, andLagothrix, were clustered together withPithecia, associated with canopy, mature forest, frugivory, and (to a lesser degree) climb/suspensory locomotion. On the other hand, the three species ofCebususually formed a loose cluster, located in the center of the cloud of species. Lastly, the Callitrichinae, involving two species ofSaguinusandCebuella, were relatively dispersed and frequently associated with liana forest, lianas, understory, and faunivory. However,Cebuellawas consistently isolated and associated with liana forest, lianas, body weight, understory, and vertical supports. In this way, clusters appeared to conform to the major platyrrhine taxonomic groups, supporting the fact that basic ecological and behavioral adaptations have evolved in a phylogenetic context. In addition, the analyses revealed that body weight, forest type and layer, feeding behavior, and locomotion are the most important variables that have apparently shaped or driven the adaptive zones of extant platyrrhines. Am J Phys Anthropol, 2003. © 2003 Wiley‐Liss, Inc.
Influence of Plio‐Pleistocene aridification on human evolution: Evidence from paleosols of the Turkana Basin, Kenya
Authors: Wynn Jonathan Guy
Published: January 2004

New stable carbon isotope measurements, coupled with paleoprecipitation estimates, both from Plio‐Pleistocene paleosols of the Turkana Basin, Kenya, provide a high‐resolution record of aridification and increasing C4biomass during the past 4.3 Ma. This aridification trend is marked by several punctuations at 3.58–3.35, 2.52–2, and 1.81–1.58 Ma, during which the running mean and variance of δ13C and paleoaridity estimates increase, suggesting that the proportion of C4biomass increases in savanna mosaics during periods of heightened aridity. Increase in C4biomass during these aridification events not only increases the proportion of open habitats, but increases the spatial neg‐entropy, or heterogeneity of the ecosystem. The aridification events identified correspond to intervals of increased turnover, but more importantly, increased diversity of bovids. Although the record of hominins from the Turkana Basin lacks the temporal resolution and diversity of the bovid record, the aridification intervals identified are marked by similar increases in the diversity and turnover of hominins. These results support the hypothesis that hominins evolved in savanna mosaics that changed through time, and suggest that the evolution of bovids and hominins was driven by shifts in climatic instability and habitat variability, both diachronic and synchronic. Am J Phys Anthropol, 2003. © 2003 Wiley‐Liss, Inc.
The paleoecology and archaeology of long‐term water storage in a Hohokam reservoir, southwestern Arizona, U.S.A.
Authors: Bayman James M. , Palacios‐Fest Manuel R. , Fish Suzanne K. , Huckell Lisa W.
Published: January 2004

Water storage reservoirs were an important feature of economic organization among ancient societies in the North American Southwest. Analyses of reservoir sediments from a Hohokam archaeological site in the Sonoran Desert yielded taxonomic species of ostracodes (microscopic crustaceans) and pollen grains that are indicative of a past water‐rich environment. The discovery that this reservoir was capable of storing water on a long‐term basis indicates that archaeological models for the region, which have relied on direct historic analogy, must be reexamined. In contrast to the local ethnographic record, paleoecological data generated by this study imply that the Hohokam could establish permanent desert settlements with water storage reservoirs away from perennial rivers and streams. Moreover, residents of these areas were geographically positioned to facilitate the circulation of marine resources (i.e., salt and shell) from the Gulf of California to territories within and beyond the Hohokam region. © 2004 Wiley Periodicals, Inc.
Short contribution: Marine erosion and archaeological landscapes: A case study of stone forts at cliff‐top locations in the Aran Islands, Ireland
Authors: Williams D. Michael
Published: January 2004

Two massively constructed stone forts exist on the edge of vertical coastal cliffs on the Aran Islands, Ireland. One of these, Dun Aonghusa, contains evidence of occupation that predates the main construction phases of the walls and broadly spans a time interval of 3300–2800 yr B.P. The other fort, Dun Duchathair, has been termed a promontory fort because its remaining wall crosses the neck of a small promontory marginal to the cliffs. Estimates of past rates of marine erosion in this part of Ireland may be made both by analogy with studies in other areas and comparison with present day rates of marine erosion. A working model for erosion rates of approximately 0.4 m of coastal recession per annum is suggested. By applying this rate to the cliffs of the Aran Islands, it can be shown that, assuming a construction date of approximately 2500 yr B.P. for these forts, they were originally built at a considerable distance from the coastline. Thus Dun Duchathair was not a promontory fort. The earliest recorded habitation at Dun Aonghusa, dated to the middle of the Bronze Age, was, therefore, at some distance inland and not on an exposed 70 m high cliff on the edge of the Atlantic Ocean. © 2004 Wiley Periodicals, Inc.
Relationship between levels of urinary type IV collagen and renal injuries in patients with IgA nephropathy
Authors: Io Hiroaki , Hamada Chieko , Fukui Mitsumine , Horikoshi Satoshi , Tomino Yasuhiko
Published: January 2004

Because type IV collagen is synthesized by podocytes and mesangial cells, we investigated the relationship between levels of urinary type IV collagen (uIV) and renal injuries in patients with IgA nephropathy. uIV was measured by a highly sensitive one‐step sandwich enzyme immunoassay prior to renal biopsy. Patients with IgA nephropathy were classified into four grades (grade 1 = good prognosis, grade 2 = relatively good prognosis, grade 3 = relatively poor prognosis, and grade 4 = poor prognosis) by the prognostic criteria of the Ministry of Health, Labor, and Welfare of Japan. Levels of uIV in grade 4 were significantly higher than those in grades 1–3. These levels tended to increase gradually due to progression of renal injuries. The grades were further divided into two groups: group I (good or relatively good prognoses) and group II (relatively poor or poor prognoses). Patients with proteinuria of <1.0 g/day were defined as groups Ip and IIp. The levels of uIV in group II were significantly higher than those in group I, and those in group IIp were significantly higher than those in group Ip. It appears that the level of uIV can be a useful marker for detection of renal injuries in IgA nephropathy. J. Clin. Lab. Anal. 18:14–18, 2004. © 2004 Wiley‐Liss, Inc.
Overestimation of HDL‐cholesterol using a homogeneous “Direct” assay
Authors: Zhao Wei , Chaffin Carolyn , Desmond Renee A. , Hodges Bruce , Daly Thomas M. , Andrew Robinson C. , Hardy Robert W.
Published: January 2004

Direct HDL‐cholesterol (HDLc) assays have several advantages over other assays that are more laborious and time‐consuming. A recent College of American Pathologists (CAP) report indicates that at least 385 Beckman LX‐20 analyzers use the selective detergent (homogeneous or direct) method for analyzing HDLc. There is no published evaluation of direct HDLc assays on the Beckman platform. Here we report our evaluation of a direct HDLc assay marketed by Beckman for the Beckman LX‐20 analyzers. In general, the assay performed well; however, the total error was not within National Cholesterol Education Program (NCEP) guidelines. This was largely because of a significant positive bias that appeared to be due, at least in part, to triglycerides. This bias was worse at HDLc concentrations <40 mg/dL, which may make it difficult to identify a low HDLc concentration and consequently an increased risk for cardiovascular disease (CVD). J. Clin. Lab. Anal. 18:42–44, 2004. © 2004 Wiley‐Liss, Inc.