bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cost efficiency in primary care contracting: a stochastic frontier cost function approach
Authors: Puig‐Junoy Jaume , Ortún Vicente 
Published: March 2004

AbstractThe principal aim of this paper is to estimate a stochastic frontier cost function and an inefficiency effects model in the analysis of the primary health‐care services purchased by the public authority and supplied by 180 providers in 1996 in Catalonia. The evidence from our sample does not support the premise that contracting out has helped improve purchasing cost efficiency in primary care. Inefficient purchasing cost was observed in the component of this purchasing cost explicitly included in the contract between purchaser and provider. There were no observable incentives for the contracted‐out primary health‐care teams to minimise prescription costs, which were not explicitly included in the contracting system. Copyright © 2004 John Wiley & Sons, Ltd.
Deriving welfare measures from discrete choice experiments: a response to Ryan and Santos Silva
Authors: Lancsar Emily , Savage Elizabeth 
Published: March 2004

AbstractIn this response we start by highlighting the key area of agreement between the commentaries and our original paper: if there is uncertainty regarding which alternative will be chosen, in a DCE or in the real world, then the compensating variation as modified for discrete data by Small and Rosen is the appropriate method of deriving welfare measures from DCEs. Both commentators point out circumstances in which the method traditionally used in the health economics arena may be consistent with the compensating variation. We show that these circumstances require a number of potentially unrealistic and ad hoc assumptions, and argue that using the traditional method could produce erroneous welfare estimates if these assumptions fail to hold in practice. We show that the compensating variation method can accommodate each of the special cases raised by the commentators and therefore is the more general and appropriate approach to deriving welfare measures from DCEs. We also respond to issues raised regarding the estimation of DCEs in general and our application to asthma medication in particular. Copyright © 2004 John Wiley & Sons, Ltd.
Primary mucosal desmoplastic melanoma of the head and neck
Authors: Prasad Manju L. , Patel Snehal G. , Busam Klaus J 
Published: March 2004

AbstractBackground.Desmoplastic variants of melanoma rarely affect the mucosa.Method.The clinicopathologic features and p53 status of seven primary mucosal desmoplastic melanomas of the oral and nasal cavity were studied.Results.The patients included six men and one woman (median age, 61 years; range, 23–74 years). Desmoplastic melanoma involved the lip in two, alveolus in three, buccal mucosa in one, and nasal vestibule in one patient. Four tumors infiltrated up to lamina propria, and three infiltrated bone and/or cartilage. All were amelanotic spindle cell tumors, five were neurotropic, and two were vasoinvasive. Aberrant p53 expression was seen in six tumors. All tumors recurred locally, and distant metastasis developed in three. Six patients died with disease (survival, 1–41 years; median, 8 years), and one patient was free of disease (survival 20 years).Conclusions.Primary mucosal desmoplastic melanomas are clinically characterized by local recurrence and may lead to distant metastasis and death even after several years. Alterations in p53 expression are frequently associated with desmoplastic melanoma. © 2003 Wiley Periodicals, Inc. Head Neck 26: 373–377, 2004
Swallowing dysfunction after chemoradiation for advanced squamous cell carcinoma of the head and neck
Authors: Kotz Tamar , Costello Rosemary , Li Yi , Posner Marshall Roy 
Published: March 2004

AbstractBackground.Swallowing dysfunction is a common side effect of chemoradiation.Methods.Twelve patients with stage III or IV squamous cell carcinoma of the head and neck were enrolled. Videofluorographic swallowing studies were performed before initiation of chemoradiation to provide baseline swallowing function data. Postchemoradiation videofluorographic swallowing studies were performed from 1 to 14 weeks after the completion of treatment (mean, 8 weeks).Results.Changes in swallowing physiology after treatment included decreased base of tongue to posterior pharyngeal wall contact (p = .0010) and reduced pharyngeal contraction (p = .0313), resulting in impaired bolus transport through the pharynx. In addition, decreased laryngeal elevation (p = .0039), decreased laryngeal vestibule closure (p = .0078), and laryngeal penetration (p = .0078) were present. Bolus volume did not have a significant effect on swallowing ability. Aspiration was observed in four patients.Conclusions.Organ preservation treatment impairs movement of structures essential for normal swallowing. Prophylactic swallowing exercises may benefit these patients. © 2004 Wiley Periodicals, Inc. Head Neck 26: 365–372, 2004
Common pathway in the medial temporal lobe for storage and recovery of words as revealed by event‐related functional MRI
Authors: Daselaar Sander M. , Veltman Dick J. , Witter Menno P. 
Published: March 2004

AbstractLesion studies have provided compelling evidence that episodic memory is dependent on the integrity of the medial temporal lobe (MTL). This role of the MTL in episodic memory has been supported by several neuroimaging studies during both episodic encoding and retrieval. After two meta‐analyses of positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies, we investigated a possible dissociation within the MTL memory system in relation to encoding and retrieval processes. Based on previous reports that specifically related the function of the MTL in episodic memory to successful encoding and actual recovery of information, we applied event‐related fMRI to compare successful encoding of words (ES) directly with successful recognition of those same words (RS). Our results did not indicate a clear dissociation between encoding and retrieval activations in the MTL. Instead, a region in the left MTL, covering the parahippocampal cortex and hippocampal formation, which was activated during ES almost completely overlapped with the area that was activated during RS. An additional region in the left anterior MTL, including the entorhinal cortex, was found to be activated exclusively during ES. Research has indicated that a large percentage of cells in this region are particularly sensitive to the relative novelty of stimuli. Our results, therefore, suggest that the parahippocampal/hippocampal region is involved in the formation and subsequent reactivation of memory traces, whereas the activity observed in the entorhinal cortex may reflect elementary memory processes related to novelty detection. © 2003 Wiley‐Liss, Inc.
Impaired place navigation in place and matching‐to‐place swimming pool tasks follows both retrosplenial cortex lesions and cingulum bundle lesions in rats
Authors: Harker K. Troy , Whishaw Ian Q. 
Published: March 2004

AbstractThe retrosplenial (RS) cortex (area 29) and the adjacent cingulum bundle (CG) are components of neural circuits that include the hippocampus. Given the evidence suggesting that the hippocampus plays a central role in spatial navigation, several lines of investigation have examined the possible contributions of these structures to spatial navigation. The combined and/or separate contributions of these structures have been difficult to establish because their close proximity usually results in combined injury after lesions and because there have been conflicting results related to lesion type and the strain of rat subjects. The purpose of the present study was to compare the effects of selective CG damage with selective RS damage in Long‐Evans rats, a domestic rat strain that displays superior spatial skills, and by using spatial behavior assessment procedures that are sensitive to CG damage. Rats with cytotoxic N‐methyl‐D‐aspartate (NMDA) RS lesions or surgical CG transection were tested on two spatial tasks in the Morris water task; a place learning task, sensitive to nonspatial and spatial behavior, and a matching‐to‐place task, sensitive to spatial behavior. Both the RS and CG groups were impaired on most measures relative to the control group on both the place task and the matching‐to‐place task. The results are discussed in relation to the anatomical organization of CG and RG projections to the hippocampus and with respect to their possible separate/conjoint contributions to spatial behavior. © 2004 Wiley‐Liss, Inc.
Immunolocalization of metabotropic glutamate receptor 1α (mGluR1α) in distinct classes of interneuron in the CA1 region of the rat hippocampus
Authors: Ferraguti Francesco , Cobden Philip , Pollard Marie , Cope David , Shigemoto Ryuichi , Watanabe Masahiko , Somogyi Peter 
Published: March 2004

AbstractIn the hippocampal CA1 region, metabotropic glutamate subtype 1 (mGluR1) receptors have been implicated in a variety of physiological responses to glutamate, which include modulation of synaptic transmission and plasticity, as well as neuronal excitability and synchronization. The mGluR1α isoform is characteristically expressed only by nonprincipal cells, and it is particularly enriched in somatostatin (SS)‐containing interneurons in stratum oriens‐alveus. Anatomical and physiological data have indicated the presence of mGluR1α in several distinct classes of interneurons with their somata located also in strata pyramidale, radiatum, and lacunosum moleculare. Each different interneuron subtype, as defined by functionally relevant criteria, including input/output characteristics and expression of selective molecular markers, subserves distinct functions in local hippocampal circuits. We have investigated which of the different CA1 interneuron classes express mGluR1α by immunofluorescent labeling, combining antibodies to mGluR1α, calcium‐binding proteins, and neuropeptides, and by intracellular labeling in vitro. Several types of interneuron that are immunopositive for mGluR1α each targeted different domains of pyramidal cells and included (1) O‐LM interneurons, found to coexpress both SS and parvalbumin (PV); (2) interneurons with target selectivity for other interneurons, expressing vasoactive intestinal polypeptide (VIP) and/or the calcium‐binding protein calretinin; (3) pro‐cholecystokinin‐immunopositive interneurons probably non‐basket and dendrite‐targeting; and (4) an as‐yet unidentified SS‐immunoreactive but PV‐immunonegative interneuron class, possibly corresponding to oriens‐bistratified cells. Estimation of the relative proportion of mGluR1α‐positive interneurons showed 43%, 46%, and 30% co‐labeling with SS, VIP, or PV, respectively. The identification of the specific subclasses of CA1 interneurons expressing mGluR1α provides the network basis for assessing the contribution of this receptor to the excitability of the hippocampus. © 2004 Wiley‐Liss, Inc.
Spatial reference memory in GluR‐A‐deficient mice using a novel hippocampal‐dependent paddling pool escape task
Authors: Schmitt W.B. , Deacon R.M.J. , Reisel D. , Sprengel R. , Seeburg P.H. , Rawlins J.N.P. , Bannerman D.M. 
Published: March 2004

AbstractGenetically modified mice lacking the L‐α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA) receptor subunit, GluR‐A (GluR1), and deficient in hippocampal CA3‐CA1 long‐term potentiation (LTP), were assessed on a novel, hippocampal‐dependent spatial reference memory, paddling pool escape task. The mice were required to use the extramaze cues around the laboratory to find a hidden escape tube that was in a constant location at one of 12 possible positions around the perimeter of the paddling pool, in order to escape from shallow water. The knockout mice performed well on this task. They displayed a small initial impairment (in terms of both escape latencies and choice errors), but they were soon as efficient as the wild‐type mice in escaping from the water. This was further demonstrated by performance during a 20‐s probe trial in which the exit tube was blocked. Both groups of mice spent most of the time searching in the quadrant of the pool in which the exit tube had previously been located. In a subsequent experiment, entirely normal spatial acquisition was observed in the knockout mice when the paddling pool was moved to a novel spatial environment. The GluR‐A−/− mice were also unimpaired in a further reversal phase in which the correct exit location was moved by 180° around the perimeter wall. These results are consistent with previous watermaze studies, providing further demonstration of intact hippocampus‐dependent spatial reference memory in GluR‐A knockout mice. They contrast strikingly with the profound deficits in hippocampus‐dependent, short‐term, flexible spatial working memory observed in these knockout mice. This study also demonstrates a novel behavioral task for assessing spatial memory in genetically modified mice. This task shares the behavioral profile of the well‐established watermaze paradigm, but may have advantages for the study of genetically modified mice. © 2004 Wiley‐Liss, Inc.
Properties of horizontal axo‐axonic cells in stratum oriens of the hippocampal CA1 area of rats in vitro
Authors: Ganter Paul , Szücs Peter , Paulsen Ole , Somogyi Peter 
Published: March 2004

AbstractLocal‐circuit γ‐aminobutyric acid (GABA)ergic interneurons constitute a diverse population of cells, which remain poorly defined into functionally distinct subclasses. Traditionally, dendritic and axonal arbors have been used to describe cell classes. In the present report, we characterize a set of hippocampal interneurons, horizontal axo‐axonic cells, located in stratum oriens. They displayed the pattern of axonal arborization characteristic of axo‐axonic cells with radially aligned rows of boutons making synapses exclusively on axon initial segments of pyramidal cells, as shown by electron microscopy. However, in contrast to previously described axo‐axonic cells, which have radial dendrites spanning all layers, the dendrites of the horizontal axo‐axonic cells were restricted to stratum oriens and ran parallel with the layers for several hundred micrometers. Single action potentials elicited by depolarizing current steps in these cells were often followed by a fast‐ and medium‐duration afterhyperpolarization, distinguishing them from fast‐spiking interneurons. In two out of four cells, trains of action potentials showed prominent early spike frequency adaptation and a characteristic “accommodative hump.” Excitatory postsynaptic potentials (EPSPs) could be evoked by stimuli delivered to stratum oriens. Paired recordings unequivocally confirmed direct synaptic inputs from CA1 pyramidal cells. The kinetics of the EPSPs were fast (rise time 1.7 ± 0.6 ms, mean ±SD, n = 3; decay time constant 19.3 ± 2.4 ms). They showed paired‐pulse depression with inter‐stimulus intervals of 10–50 ms. One pair showed a reciprocal connection establishing a direct feedback loop. The axo‐axonic cell‐evoked inhibitory postsynaptic potentials (IPSPs) were reliable (failure rate ∼10%). Our data show that the laminar distribution of the dendrites of axo‐axonic cells can vary, suggesting distinct synaptic inputs. However, this remains to be shown directly, and we cannot exclude the possibility that all axo‐axonic cells may gather similar synaptic input, leaving them as one distinct class of interneuron. © 2004 Wiley‐Liss, Inc.
Expression of long‐term potentiation in aged rats involves perforated synapses but dendritic spine branching results from high‐frequency stimulation alone
Authors: Dhanrajan Tiruchinapalli M. , Lynch Marina A. , Kelly Aine , Popov Victor I. , Rusakov Dmitri A. , Stewart Michael G. 
Published: March 2004

AbstractEvidence for morphological substrates of long‐term changes in synaptic efficacy is controversial, partly because it is difficult to employ an unambiguous control. We have used a high‐frequency stimulation protocol in vivo to induce long‐term potentiation (LTP) in the hippocampal dentate gyrus of aged (22‐month‐old) rats and have found a clear distinction between animals that sustain LTP and those that fail to sustain it. The “failure group” was used as a specific/“like‐with‐like” control for morphological changes associated with the expression of LTP per se. Quantitative optical and electron microscopy was used to analyze large populations of dendritic spines and excitatory perforant path synapses; LTP was found to be associated with an increase in numbers of segmented (perforated) postsynaptic densities in spine synapses. In contrast, an increase in the number of branched spines appears to result from high‐frequency stimulation alone. These data shed light on the current controversy about the expression mechanism of LTP. © 2004 Wiley‐Liss, Inc.
Endogenous 5‐HT inhibits firing activity of hippocampal CA1 pyramidal neurons during conditioned fear stress‐induced freezing behavior through stimulating 5‐HT1A receptors
Authors: Tada Koji , Kasamo Kimihiro , Suzuki Tadashi , Matsuzaki Yamato , Kojima Takuya 
Published: March 2004

AbstractThis study examines the activity of hippocampal CA1 pyramidal neurons during conditioned fear stress (CFS)‐induced freezing behavior in unanesthetized, unrestrained rats. The firing frequency of hippocampal CA1 pyramidal neurons was significantly decreased when conditioned rats exhibited freezing behavior. Firing frequency returned to the baseline after freezing behavior disappeared. The selective 5‐hydroxytryptamine (5‐HT)1A antagonists, N‐[2‐[4‐(2‐methoxyphenyl)‐1‐piperazinyl]ethyl]‐N‐(2‐pyridinyl)cyclohexanecarboxamide (WAY‐100635), and N‐tert‐butyl‐3‐[4‐(2‐methoxyphenyl)piperazine‐1‐yl]‐2‐phenylpropamide (WAY‐100135) and 5‐HT depletion with parachlorophenylalanine (PCPA) completely abolished the decrease in firing frequency during CFS‐induced freezing behavior. These results suggested that endogenous 5‐HT inhibited the firing activity of hippocampal CA1 pyramidal neurons during CFS‐induced freezing behavior mainly through stimulating 5‐HT1A receptors. © 2004 Wiley‐Liss, Inc.
Hippocampal prosaposin changes during stress: A glucocorticoid‐independent event
Authors: Scaccianoce Sergio , Mattei Vincenzo , Del Bianco Paola , Gizzi Chiara , Sorice Maurizio , Hiraiwa Masao , Misasi Roberta 
Published: March 2004

AbstractSeveral studies indicate that stress can produce remarkable effects on neurotrophic factors. In this regard, hippocampus is the most interesting structure of the brain because of its broad involvement in behavioral and neuroendocrine phenomena. In the present study, we investigated the effect of stress on hippocampal prosaposin, which is known to act as a neurotrophic and neuroprotective factor. Rats subjected to restraint stress (120 min) had a significant and transient reduction of hippocampal, but not hypothalamic, prosaposin full‐length protein. Indeed, when this stressful stimulus was applied daily for 3 days, no differences were detected in comparison with naive rats. To investigate the role of glucocorticoids in the stress‐induced decrease in hippocampal prosaposin, adrenalectomized and corticosterone‐treated rats were studied. The results indicate that adrenalectomized rats behave as intact animals. This finding indicates that the absence of endogenous corticosterone does not prevent a decrease in hippocampal prosaposin. When an increase of corticosterone was achieved through exogenous administration, hippocampal prosaposin concentrations were unchanged in comparison with vehicle‐injected (sesame oil) rats. These results led to the conclusion that stress, not via an increase of glucocorticoid hormone, transiently reduces hippocampal prosaposin levels. This phenomenon is followed by rapid recovery of the neurotrophin level, even when the stress stimulus persists. © 2004 Wiley‐Liss, Inc.
Muscarinic signaling is required for spike‐pairing induction of long‐term potentiation at rat Schaffer collateral‐CA1 synapses
Authors: Adams Scott V. , Winterer Jochen , Müller Wolfgang 
Published: March 2004

AbstractCholinergic input from the basal forebrain and septum to the hippocampus is well known to be critical in learning and memory. Muscarinic induction of theta‐frequency oscillations may synchronize pre‐ and postsynaptic firing and thereby enhance plasticity in the hippocampus. Previous studies have demonstrated that muscarinic activation facilitates long‐term potentiation (LTP) induced with tetanus in vitro. In the present study, we tested the role of muscarinic receptor activity in the induction of LTP beyond effects on spike timing by using a spike‐pairing (SP) method at Schaffer collateral‐CA1 synapses in rat hippocampal slices. Pairings of pre‐ and postsynaptic action potentials (APs) have been shown to induce LTP when the presynaptic AP precedes the postsynaptic AP by 5–15 ms, but contribution of muscarinic co‐activation has not been ruled out. We demonstrate that the mAChR antagonist atropine abolishes LTP induction by SP. Surprisingly, prolonged exposure to the mAChR agonist carbachol inhibits LTP induction by SP, perhaps because of receptor desensitization. These results demonstrate an essential role of cholinergic signaling in this form of hippocampal plasticity. © 2004 Wiley‐Liss, Inc.
Homeostatic maintenance in excitability of tree shrew hippocampal CA3 pyramidal neurons after chronic stress
Authors: Kole Maarten H.P. , Czéh Boldizsár , Fuchs Eberhard 
Published: March 2004

AbstractThe experience of chronic stress induces a reversible regression of hippocampal CA3 apical neuron dendrites. Although such postsynaptic membrane reduction will obviously diminish the possibility of synaptic input, the consequences for the functional membrane properties of these cells are not well understood. We tested the hypothesis that chronic stress affects the input‐output characteristics and excitability of CA3 pyramidal cells. Somatic whole‐cell current‐clamp recording with parallel intracellular biocytin labeling was performed on CA3 neurons from in vitro hippocampal slices from male tree shrews, which were collected after 28 days of psychosocial stress exposure and compared to recordings obtained from control animals. Post hoc morphometric analysis of biocytin‐labeled CA3 cells revealed branch regression, by fewer dendritic crossings and length, limited to a distance of ∼280–340 μm from the soma only. The results from whole‐cell recording indicate that chronic stress surprisingly reduced the apparent membrane time constant and input resistance 20–25%, accompanied by increased amplitude of the hyperpolarization‐induced voltage “sag.” All active membrane properties, including depolarization‐induced action potential kinetics, complex spiking patterns, and afterhyperpolarization voltages, were indistinguishable from control recordings. Although linear association analysis confirmed that differences in geometry, such as apical length or branch number, were correlated to functional variability in properties of the AP current and voltage threshold, these changes were too marginal to be reflected in the group differences. However, the individual adrenal hormone status was associated significantly with the selective changes in subthreshold excitability. Taken together, the data provide evidence that despite long‐term stress induces morphological changes, upregulates cortisol release and shifts the intrinsic membrane properties, the efficacy of somatic excitability of CA3 pyramidal neurons is largely preserved. © 2004 Wiley‐Liss, Inc.