bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spinal cord plasticity in response to unilateral inhibition of the rat motor cortex during development: changes to gene expression, muscle afferents and the ipsilateral corticospinal projection
Authors: Clowry G. J. , Davies B. M. , Upile N. S. , Gibson C. L. , Bradley P. M. 
Published: November 2004

AbstractIn developing Wistar albino rats, ventral horn muscle afferent boutons are lost following corticospinal innervation. Motor cortex lesions rescue a proportion of these boutons and perturb activity dependent expression of cJun and parvalbumin (PV) in the spinal cord. Therefore, we tested whether activity‐dependent competition between corticospinal and proprioreceptive afferents determines the balance of these inputs to motor output pathways by delivering the inhibitory GABA agonist muscimol unilaterally to the forelimb motor cortex using slow release polymer implants from postnatal day 7 (P7) coincident with corticospinal synaptogenesis. Controls received saline. Inhibition of immature cortical neurons by muscimol was confirmed with separate in vitro electrophysiological recordings. After P28, spinal cord sections were immunostained for PV, cJun and muscle afferents transganglionically labelled with cholera toxin‐B (CTB). Unilateral inhibition reduced contralaterally the number of PV positive spinal cord neurons and muscle afferent boutons in the dorsolateral ventral horn, compared to controls, and significantly altered the distribution of motoneuronal cJun expression. Separately, descending tracts were retrogradely traced with CTB from the cervical hemicord contralateral to implants. Forelimb sensorimotor cortex sections were immunostained for either CTB or PV. In muscimol treated animals, significantly fewer neurons expressed PV in the inhibited hemicortex, but as many CTB labelled corticospinal neurons were present as in controls, along with an equally large corticospinal projection from contralateral to the implant, significantly greater than in controls. Unexpectedly, unilateral inhibition of the motor cortical input did not lead to an expanded muscle afferent input. Instead, this was reduced coincident with development of a bilateral corticospinal innervation.
The corticoid environment: a determining factor for neural progenitors' survival in the adult hippocampus
Authors: Wong Edmund Y. H. , Herbert Joe 
Published: November 2004

AbstractNew neurons continue to be generated in the adult dentate gyrus of the hippocampus. Corticosterone (CORT), a steroid secreted by the adrenal glands, had been shown to regulate progenitor proliferation. High levels of CORT suppress proliferation while low levels of the steroid stimulate it. Here we present an investigation into the regulation of survival by corticoids, with emphasis on the differential effects of the pre‐mitotic and post‐mitotic corticoid environments. Post‐mitotic adrenalectomy increased subsequent survival of progenitors at 28 days, while additional CORT administered during the post‐mitotic period decreased survival. In contrast, a corticoid‐free environment prior to progenitor division resulted in a reduced survival rate of new cells and, similarly, high levels of CORT before proliferation reduced subsequent survival. In addition, phased treatment with CORT during a 27‐day post‐mitotic interval showed that newly formed cells lose their sensitivity to administered CORT after about 18 days. These results are the first to show that the corticoid environment both before and after cell division regulates survival.
Reelin receptors in developing laminated brain structures of mouse and human
Authors: Perez‐Garcia C. G. , Tissir F. , Goffinet A. M , Meyer G. 
Published: November 2004

AbstractReelin is an extracellular matrix protein secreted by a variety of cell types throughout the developing brain. The target cells for reelin express the cytoplasmic adapter protein Dab1, which binds to the reelin receptors VLDLR and ApoER2. In the present work, we have studied the localization of both receptors in developing mouse and human cortex, olfactory bulb and cerebellum. In mouse, some Cajal–Retzius cells express reelin and VLDLR; in humans, all the components of the signalling pathway (Reelin, Dab1, VLDLR and ApoER2) are present in subsets of Cajal–Retzius cells. In the mouse cortical plate, VLDLR and ApoER2 are present from E15 to postnatal stages; in human cortical plate they are most prominent at ≈ 20 gestational weeks. In mice, cerebellar Purkinje cells only express VLDLR whereas in humans they express both VLDLR and ApoER2. Mitral cells of the mouse olfactory bulb are ApoER2‐positive and VLDLR‐negative. In sum, the receptor expression patterns are similar in the human and mouse cortical plate but differ in Cajal–Retzius and Purkinje cells, which in humans express additional components of the reelin–Dab1 pathway.
Fast onset of dopamine uptake inhibition by intravenous cocaine
Authors: Mateo Yolanda , Budygin Evgeny A. , Morgan Drake , Roberts David C. S. , Jones Sara R. 
Published: November 2004

Abstract In vivo voltammetry in the nucleus accumbens of anesthetized rats was used to investigate the time of onset of dopamine uptake inhibition by intravenous cocaine. There is disagreement between behavioral and neurochemical studies concerning the time‐course of cocaine effects. Because of the high temporal resolution of voltammetry, the processes of dopamine release and uptake could be temporally separated to make evaluation of cocaine effects on uptake easier to address. Within 4 s after intravenous cocaine administration (1.5 mg/kg) there was significant inhibition of dopamine uptake that reached a plateau in 20 s. The peak heights of electrically evoked dopamine signals were also rapidly increased by cocaine. The signals returned to baseline values within approximately 1 h. In parallel behavioral studies, locomotor activity was significantly increased within 5–6 s following intravenous infusion of cocaine. Here we demonstrate that intravenous cocaine administration begins inhibiting the uptake of dopamine within a few seconds. This is at least 10‐fold faster than previous neurochemical estimates. The present findings may contribute to the understanding of the neurobiological mechanisms underlying the early behavioral responses to cocaine.
Expression profiling in laser‐microdissected hippocampal subregions in rat brain reveals large subregion‐specific differences in expression
Authors: Datson N. A. , Meijer L. , Steenbergen P. J. , Morsink M. C. , Van Der Laan S. , Meijer O. C. , De Kloet E. R. 
Published: November 2004

AbstractExpression profiling in the hippocampus is hampered by its cellular heterogeneity. The aim of this study was to evaluate the feasibility of using laser‐microdissected hippocampal subregions for expression profiling to improve detection of transcripts with a subregion‐specific expression. Cornu ammonis (CA)3 and dentate gyrus (DG) subregions were isolated from rat brain slices using laser microdissection, subjected to two rounds of linear amplification and hybridized to rat GeneChips containing approximately 8000 transcripts (RG_U34A; Affymetrix). Analysis of the data using significance analysis of microarrays revealed 724 genes with a significant difference in expression between CA3 and DG with a false discovery rate of 2.1%, of which 264 had higher expression in DG and 460 in CA3. Several transcripts with known differential expression between the subregions were included in the dataset, as well as numerous novel mRNAs and expressed sequence tags. Sorting of the differentially expressed genes according to gene ontology classification revealed that genes involved in glycolysis and general metabolism, neurogenesis and cell adhesion were consistently expressed at higher levels in CA3. Conversely, a large cluster of genes involved in protein biosynthesis were expressed at higher levels in DG. In situ hybridization was used to validate differential expression of a selection of genes. The results of this study demonstrate that the combination of laser microdissection and GeneChip technology is both technically feasible and very promising. Besides providing an extensive inventory of genes showing differential expression between CA3 and DG, this study supports the idea that profiling in hippocampal subregions should improve detection of genes with a subregion‐specific expression or regulation.
Interneurone bursts are spontaneously associated with muscle contractions only during early phases of mouse spinal network development: a study in organotypic cultures
Authors: Rosato‐Siri Marcelo D. , Zoccolan Davide , Furlan Francesco , Ballerini Laura 
Published: November 2004

AbstractFor a short time during development immature circuits in the spinal cord and other parts of the central nervous system spontaneously generate synchronous patterns of rhythmic activity. In the case of the spinal cord, it is still unclear how strongly synchronized bursts generated by interneurones are associated with motoneurone firing and whether the progressive decline in spontaneous bursting during circuit maturation proceeds in parallel for motoneurone and interneurone networks. We used organotypic cocultures of spinal cord and skeletal muscle in order to investigate the ontogenic evolution of endogenous spinal network activity associated with the generation of coordinate muscle fibre contractions. A combination of multiunit electrophysiological recordings, videomicroscopy and optical flow computation allowed us to measure the correlation between interneurone firing and motoneurone outputs after 1, 2 and 3 weeks of in vitro development. We found that, in spinal organotypic slices, there is a developmental switch of spontaneous activity from stable bursting to random patterns after the first week in culture. Conversely, bursting recorded in the presence of strychnine and bicuculline became increasingly regular with time in vitro. The time course of spontaneous activity maturation in organotypic slices is similar to that previously reported for the spinal cord developing in utero. We also demonstrated that spontaneous bursts of interneurone action potentials strongly correlate with muscular contractions only during the first week in vitro and that this is due to the activation of motoneurones via AMPA‐type glutamate receptors. These results indicate the occurrence in vitro of motor network development regulating bursting inputs from interneurones to motoneurones.
Somatostatin receptors differentially affect spontaneous epileptiform activity in mouse hippocampal slices
Authors: Cammalleri Maurizio , Cervia Davide , Langenegger Daniel , Liu Yanqiang , Monte Massimo Dal , Hoyer Daniel , Bagnoli Paola 
Published: November 2004

AbstractSomatostatin‐14 [somatotropin release‐inhibiting factor (SRIF)] reduces hippocampal epileptiform activity but the contribution of its specific receptors (sst1−5) is poorly understood. We have focused on the role of sst1 and sst2 in mediating SRIF modulation of epilepsy using hippocampal slices of wild‐type (WT) and sst1 or sst2 knockout (KO) mice. Recordings of epileptiform discharge induced by Mg2+‐free medium with 4‐aminopyridine were performed from the CA3 region before and after the application of SRIF compounds. In WT mice, SRIF and the sst1 agonist CH‐275 reduce epilepsy whereas sst1 blockade with its antagonist SRA‐880 increases the bursting discharge. Activation of sst2 does not affect the bursting frequency unless its agonist octreotide is applied with SRA‐880, indicating that sst1 masks sst2‐mediated modulation of epilepsy. In sst1 KO mice: (i) the bursting frequency is lower than in WT; (ii) SRIF, CH‐275 and SRA‐880 are ineffective on epilepsy and (iii) octreotide is also devoid of effects, whereas blockade of sst2 with the antagonist d‐Tyr8 Cyn 154806 increases the bursting frequency. In sst2 KO mice, the SRIF ligand effects are similar to those in WT. In the whole hippocampus of sst1 KO mice, sst2 mRNA, protein and binding are higher than in WT and reverse transcription‐polymerase chain reaction of the CA3 subarea confirms an increase of the sst2 messenger. We conclude that sst1 mediates inhibitory actions of SRIF and that interactions between sst1 and sst2 may prevent sst2 modulation of epilepsy. We suggest that, in sst1 KO mice, activation of over‐expressed sst2 reduces the bursting frequency, indicating that sst2 density represents the rate‐limiting factor for sst2‐mediated modulation of epilepsy.
The collapse of cycles in the dynamics of North American grouse populations
Authors: Williams Christopher K. , Ives Anthony R. , Applegate Roger D. , Ripa Jörgen 
Published: November 2004

AbstractCyclic dynamics of bird and mammal populations are commonly reported in northern latitudes throughout the world, and recent European observations on rodents and grouse suggest that cycle periods decline towards southern latitudes. To investigate latitudinal patterns of cyclic dynamics in North America, we assembled 27 long‐term data sets collected between 1939 and 2001 for three grouse species. By fitting the data with autoregressive models to measure direct and delayed density dependence, we show that, in contrast to European studies, North American grouse exhibit period increases from north to south, with cycles collapsing via period lengthening. This occurs because delayed density dependence decreases in southern latitudes, whereas direct density dependence increases. These results show that cyclic dynamics can dissipate by period lengthening as well as the period shortening postulated for European grouse and rodents.
Evolution of plant resistance and tolerance to frost damage
Authors: Agrawal Anurag A. , Conner Jeffrey K. , Stinchcombe John R. 
Published: November 2004

AbstractPlant defence against any type of stress may involve resistance (traits that reduce damage) or tolerance (traits that reduce the negative fitness impacts of damage). These two strategies have been proposed as redundant evolutionary alternatives. A late‐season frost enabled us to estimate natural selection and genetic constraints on the evolution of frost resistance and tolerance in a wild plant species. We employed a genetic selection analysis (which is unbiased by environmental correlations between traits and fitness) on 75 paternal half‐sibling families of annual wild radish [Raphanus raphanistrum (Brassicaceae)]. In an experimental population in southern Ontario, we found strong selection favouring plant resistance to frost, but selection against tolerance to frost. The selection against tolerance may have been caused by a cost of tolerance, as we provide evidence for a negative genetic correlation between tolerance and fitness in the absence of frost damage. Although we found no evidence for the theoretically predicted trade‐off between frost tolerance and resistance among our families, we did detect negative correlational selection acting on the two traits, indicating that natural selection favoured high resistance combined with low tolerance and low resistance coupled with high tolerance, but not high or low levels of both traits together. There were few genetic correlations between the measured traits overall, but frost tolerance was negatively correlated with initial seed mass, and frost resistance was positively correlated with resistance to insect herbivory. Periodic episodes of strong selection such as that caused by the late‐season frost may be disproportionately important in evolution, and are likely becoming more common because of human alterations of the environment.
Darwin's cross‐promotion hypothesis and the evolution of stylar polymorphism
Authors: Cesaro Adeline C. , Thompson John D. 
Published: November 2004

AbstractThere is growing appreciation that the ecological factors which impact on rates of pollen transfer can contribute significantly to reproductive trait evolution in plants. In heterostylous species, several studies support Darwin's claim that the reciprocal positions of stigmas and anthers enhance inter‐morph mating in comparison to intra‐morph mating and thus the maintenance of the polymorphism. In this study, we evaluate the relative importance of intra‐morph and inter‐morph pollen transfers in Narcissus assoanus, a species with dimorphic variation in style length but non‐reciprocity of anther positions. This stigma‐height dimorphism represents a transitional stage in theoretical models of the evolution of distyly. Seed set variation on recipient plants with donor plants of a single morph in experimental arrays in a natural population illustrate that inter‐morph cross‐pollination is more efficient that intra‐morph cross‐pollination as a result of high rates of pollen transfer from long‐styled to short‐styled plants. The observed rates of pollen transfer satisfy the theoretical conditions for the establishment of a stigma‐height dimorphism in an ancestral monomorphic long‐styled population in pollen‐limited situations. These results provide experimental evidence for the Darwinian hypothesis that enhanced inter‐morph cross‐pollination facilitates not only the maintenance of heterostyly but also the establishment of transitional forms implicated in the evolution of this polymorphism.
The evolution of hippocampus volume and brain size in relation to food hoarding in birds
Authors: Garamszegi László Zsolt , Eens Marcel 
Published: November 2004

AbstractFood‐hoarding birds frequently use spatial memory to relocate their caches, thus they may evolve a larger hippocampus in their brain than non‐hoarder species. However, previous studies testing for such interspecific relationships provided conflicting results. In addition, food hoarding may be a cognitively complex task involving elaboration of a variety of brain regions, even outside of the hippocampus. Hence, specialization to food hoarding may also result in the enlargement of the overall brain. In a phylogenetic analysis of distantly related birds, we studied the interspecific association between food hoarding and the size of different brain regions, each reflecting different resolutions. After adjusting for allometric effects, the relative volume of the hippocampus and the relative size of the entire brain were each positively related to the degree of food‐hoarding specialization, even after controlling for migration and brood parasitism. We also found some significant evidence for the relative volume of the telencephalon being associated with food hoarding, but this relationship was dependent on the approach we used. Hence, neural adaptation to food hoarding may favour the evolution of different brain structures.
Neobladder‐vaginal fistula after cystectomy and orthotopic neobladder construction
Authors: Rapp David E. , O'Connor R. Corey , Katz Erin E. , Steinberg Gary D. 
Published: November 2004

OBJECTIVETo determine the potential surgical and clinical factors that contribute to the development of neobladder‐vaginal fistula (NVF) after cystectomy and orthotopic neobladder (ONB) construction in women.PATIENTS AND METHODSOf 37 patients who had vaginal‐sparing cystectomy, the records of four who developed a NVF after radical cystectomy and ONB construction were reviewed. Retrospective clinical and surgical information was collected, including patient demographics, tumour pathology, surgical technique, presenting symptoms, and method and efficacy of surgical repair.RESULTSIn two of the four patients who developed a NVF a small injury to the anterior vaginal wall was noted during surgery and closed primarily. All patients presented with severe urinary incontinence. The NVF was diagnosed after cystoscopy and/or speculum examination. Three of the four patients had an attempted surgical repair, including one obturator flap interposition, one rectus flap interposition, and one primary two‐layer closure. To date, one patient is fistula‐free and two were subsequently converted to an ileal conduit or continent cutaneous diversion because the fistula recurred. The fourth patient developed a NVF in association with local tumour recurrence and underwent conversion to an ileal conduit.CONCLUSIONThe development of a NVF is a significant complication after cystectomy. Inadvertent injury to the vaginal wall is an important predisposing factor to subsequent NVF development. The repair of a NVF is often difficult; upon diagnosis, conversion to a continent cutaneous urinary diversion may be considered.
Prostatic capsule‐ and seminal‐sparing cystectomy for bladder carcinoma: initial results for selected patients
Authors: Botto Henry , Sebe Philippe , Molinie Vincent , Herve Jean‐Marie , Yonneau Laurent , Lebret Thierry 
Published: November 2004

OBJECTIVETo evaluate the oncological outcome and functional results of prostate‐sparing cystectomy (PSC), proposed for treating bladder cancer, used since 1999 in our institution in an attempt to preserve male sexuality and to increase continence after cystectomy.PATIENTS AND METHODSBetween January 1999 and December 2001, 111 men were candidates for cystectomy; 42 were selected for a prostatic capsule‐ and seminal‐sparing cystectomy with orthotopic urinary diversion. All patients had clinically organ‐confined tumours (clinical stage ≤ T2, N0M0). The first stage of the procedure was a transurethral resection of the prostate to exclude the involvement of transitional cell carcinoma (TCC) in the prostate.RESULTSEight patients were excluded from PSC because they had TCC (seven) or prostate adenocarcinoma (one). The mean age of the remaining 34 patients was 61 years and all underwent PSC. After a mean follow‐up of 26 months, seven patients (21%) had a recurrence; one developed a local recurrence, there were widespread metastases in six (18%), and five had histologically confirmed organ‐confined tumour (T1‐2N0M0). Rates for daytime and night‐time continence were 90% and 85%, and in 29 patients potency was unchanged.CONCLUSIONThese early results suggest that PSC is not equivalent to radical cystoprostatectomy for bladder cancer control, despite marked improvements in the functional results. Moreover, in carefully selected patients this approach appears to dramatically increase an unusually high metastasis rate. Therefore, the indications for PSC should be either clearly well defined or abandoned in these patients.
Is laparoscopic adrenalectomy feasible for adrenocortical carcinoma or metastasis?
Authors: Porpiglia Francesco , Fiori Cristian , Tarabuzzi Roberto , Giraudo Giuseppe , Garrone Corrado , Morino Mario , Fontana Dario , Scarpa Roberto M. 
Published: November 2004

OBJECTIVETo review our experience with laparoscopic adrenalectomy (LA), to evaluate the effectiveness and safety of this procedure in patients with adrenal malignancy.PATIENTS AND METHODSThe study included patients who underwent LA from 1995 to 2002, with histologically identified adrenocortical cancer (ACC) or metastasis. Indications for LA were adrenal masses with no radiological evidence of involvement of the surrounding structures, or solitary metastasis with well‐controlled primary cancer. The variables evaluated were: size of the lesion, operative duration, estimated blood loss, intraoperative complications, local, port‐site and intra‐abdominal recurrence, distant metastasis, and survival time.RESULTSFourteen malignant adrenal lesions in 205 LAs (7%) were confirmed with histological diagnoses that showed a primary ACC in six and metastasis in another seven (in one there was bilateral metastasis). The mean (sd) size of the malignant lesions was 5.9 (2.8) cm. The 12 unilateral procedures required a mean operative duration of 164 (47) min; the bilateral procedure lasted 215 min. There was one conversion to open surgery caused by local infiltration, whereas there were no intraoperative complications. The mean follow‐up was 30 months, during which three patients died, one from endoperitoneal and trocar port‐site seeding.CONCLUSIONWhen the malignancy is confined to the adrenal gland, LA seems to be a feasible option if the principles of oncological surgery are respected. Nevertheless, further investigations are required to evaluate the appropriateness of this operation.