bluuebunny/crossref_metadata_2025_split huggingface dataset:
Repeated seizures lead to altered skilled behaviour and are associated with more highly efficacious excitatory synapses
Authors: Henry Luke C. , Goertzen Crystal D. , Lee Arden , Teskey G. Campbell 
Published: April 2008

AbstractPeople with epilepsy have a high incidence of interictal behavioural problems that appear to be related to the location of their seizure focus. This study investigated a novel test of the hypotheses that repeated seizures result in behavioural deficits and altered performance during the interictal state, and that those behaviours are related to the presence of more highly efficacious excitatory synapses. We tested these hypotheses by first repeatedly eliciting seizures with electric current through indwelling electrodes in the corpus callosum at the level of the caudal forelimb area of sensorimotor neocortex in the rat. We then assessed learned skilled behaviours that primarily utilize the forelimbs on tasks that are sensitive to the functional integrity of that structure. We observed both behavioural deficits and altered kinematic performance in rats that experienced repeated neocortical seizures relative to an electrode‐implanted control group. From a separate set of rats, tissue was prepared for quantification of thickness and excitatory synaptic subtypes from neocortical layer V. We observed significantly increased numbers of perforated synapses that make their connections directly onto the dendritic shaft at 3 weeks following the last seizure. Altered reaching behaviours are likely due to neural reorganization in the neocortex including more efficacious synapses.
Bilateral coordination of walking and freezing of gait in Parkinson’s disease
Authors: Plotnik Meir , Giladi Nir , Hausdorff Jeffrey M. 
Published: April 2008

AbstractFreezing of gait (FOG) in Parkinson's disease (PD) occurs most frequently during turns or step initiation, two tasks that likely demand a high degree of bilateral coordination between the legs. Our objective was to test the hypothesis that impairments in bilateral coordination of stepping are associated with FOG in PD. We compared locomotion features while walking on level ground between patients with PD that experience FOG (PD + FOG; n = 21) and patients with PD that do not (PD − FOG; n = 13). To study bilateral stepping coordination, we defined the stride duration of one foot as a gait cycle or 360°, determined the relative timing of contralateral heel‐strikes and defined this as the phase, ϕ (ideally, ϕ = 180°). The sum of the coefficient of variation of ϕ and the mean absolute difference between ϕ and 180° was defined as the phase coordination index (PCI), representing variability and inaccuracy, respectively, in phase generation. During the ‘Off’ state (= 12 h off anti‐parkinsonian medication), PCI values were higher (poorer coordination) in PD + FOG compared with PD − FOG (P < 0.024). Stride‐to‐stride phase adjustments, Δϕ, were also studied. Both groups scaled their ‘converging’ adjustments (towards 180°) to the same extent, but when generating diverging Δϕ (away from 180°), PD + FOG patients exhibited larger errors compared with PD − FOG patients (P < 0.006). This study demonstrates that patients with PD who experience FOG have distinctive impairments in the bilateral coordination of locomotion. Poor bilateral coordination of walking may predispose to FOG, especially during challenging tasks that demand a high degree of left–right coordination.
Interaction between neuropeptide Y (NPY) and brain‐derived neurotrophic factor in NPY‐mediated neuroprotection against excitotoxicity: a role for microglia
Authors: Xapelli S. , Bernardino L. , Ferreira R. , Grade S. , Silva A. P. , Salgado J. R. , Cavadas C. , Grouzmann E. , Poulsen F. R. , Jakobsen B. , Oliveira C. R. , Zimmer J. , Malva J. O. 
Published: April 2008

AbstractThe neuroprotective effect of neuropeptide Y (NPY) receptor activation was investigated in organotypic mouse hippocampal slice cultures exposed to the glutamate receptor agonist α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA). Exposure of 2‐week‐old slice cultures, derived from 7‐day‐old C57BL/6 mice, to 8 µm AMPA, for 24 h, induced degeneration of CA1 and CA3 pyramidal cells, as measured by cellular uptake of propidium iodide (PI). A significant neuroprotection, with a reduction of PI uptake in CA1 and CA3 pyramidal cell layers, was observed after incubation with a Y2 receptor agonist [NPY(13‐36), 300 nm]. This effect was sensitive to the presence of the selective Y2 receptor antagonist (BIIE0246, 1 µm), but was not affected by addition of TrkB‐Fc or by a neutralizing antibody against brain‐derived neurotrophic factor (BDNF). Moreover, addition of a Y1 receptor antagonist (BIBP3226, 1 µm) or a NPY‐neutralizing antibody helped to disclose a neuroprotective role of endogenous NPY in CA1 region. Cultures exposed to 8 µm AMPA for 24 h, displayed, as measured by an enzyme‐linked immunosorbent assay, a significant increase in BDNF. In such cultures there was an up‐regulation of neuronal TrkB immunoreactivity, as well as the presence of BDNF‐immunoreactive microglial cells at sites of injury. Thus, an increase of AMPA‐receptor mediated neurodegeneration, in the mouse hippocampus, was prevented by neuroprotective pathways activated by NPY receptors (Y1 and Y2), which can be affected by BDNF released by microglia and neurons.
Long‐term potentiation in the nucleus accumbens requires both NR2A‐ and NR2B‐containing N‐methyl‐d‐aspartate receptors
Authors: Schotanus Sietske M. , Chergui Karima 
Published: April 2008

Abstract N‐methyl‐d‐aspartate (NMDA) receptors play crucial roles in several forms of long‐term changes in the efficacy of glutamatergic synaptic transmission. The suggestion that the NR2A subunit of the NMDA receptor may be selectively involved in the induction of long‐term potentiation (LTP) in the hippocampus and cortex has been challenged. However, the contribution of NR2B in the induction of LTP is not always clearly established. The present study investigates the role of NR2A and NR2B in the induction of LTP in the nucleus accumbens (NAc), a brain region that expresses high levels of NR2B and an NMDA‐dependent form of LTP. We recorded extracellular field excitatory postsynaptic potentials/population spikes in slices of mouse NAc. High‐frequency stimulation of glutamatergic fibers consistently induced LTP of the field excitatory postsynaptic potential/population spike in the NAc. LTP was abolished in the presence of selective antagonists of either NR2B [R‐(R*,S*)‐α‐(4‐hydroxyphenyl)‐β‐methyl‐4‐(phenyl‐methyl)‐1‐piperidine propanol and Ifenprodil] or NR2A ([(R)‐[(S)‐1‐(4‐bromo‐phenyl)‐ethylamino]‐(2,3‐dioxo‐1,2,3,4‐tetrahydroquinoxalin‐5‐yl)‐methyl]‐phosphonic acid) subunits. Recordings performed in a low concentration of Mg2+ ions in the perfusion solution did not reveal a selective involvement of a particular NMDA receptor subunit because either NR2A or NR2B antagonists were able to block LTP. LTP was also abolished in the presence of a low concentration of the non‐subunit‐selective NMDA receptor antagonist dl‐2‐amino‐5‐phosphonopentanoic acid in normal Mg2+ and low Mg2+ in the perfusion solution. These results show that the degree of NMDA receptor activation, and not their subunit composition, determines whether LTP is induced in the NAc.
Balance training and ballistic strength training are associated with task‐specific corticospinal adaptations
Authors: Schubert M. , Beck S. , Taube W. , Amtage F. , Faist M. , Gruber M. 
Published: April 2008

AbstractThe aim of this study was to investigate the role of presumably direct corticospinal pathways in long‐term training of the lower limb in humans. It was hypothesized that corticospinal projections are affected in a training‐specific manner. To assess specificity, balance training was compared to training of explosive strength of the shank muscles and to a nontraining group. Both trainings comprised 16 1‐h sessions within 4 weeks. Before and after training, the maximum rate of force development was monitored to display changes in motor performance. Neurophysiological assessment was performed during rest and two active tasks, each of which was similar to one type of training. Hence, both training groups were tested in a trained and a nontrained task. H‐reflexes in soleus (SOL) muscle were tested in order to detect changes at the spinal level. Corticospinal adaptations were assessed by colliding subthreshold transcranial magnetic stimulation to condition the SOL H‐reflex. The short‐latency facilitation of the conditioned H‐reflex was diminished in the trained task and enhanced in the nontrained task. This was observable in the active state only. On a functional level, training increased the rate of force development suggesting that corticospinal projections play a role in adaptation of leg motor control. In conclusion, long‐term training of shank muscles affected fast corticospinal projections. The significant interaction of task and training indicates context specificity of training effects. The findings suggest reduced motor cortical influence during the trained task but involvement of direct corticospinal control for new leg motor tasks in humans.
Postsynaptic expression of an epidermal growth factor receptor regulates cholinergic synapse formation between identified molluscan neurons
Authors: Van Kesteren Ronald E. , Gagatek Jessica S. , Hagendorf Antje , Gouwenberg Yvonne , Smit August B. , Syed Naweed I. 
Published: April 2008

AbstractEpidermal growth factor (EGF) family members are conserved in both vertebrates and invertebrates. Recent studies suggest that EGF ligands in invertebrates may have neurotrophic actions that possibly compensate for the apparent absence of neurotrophins in these species. In this study, we have cloned an EGF receptor from the mollusk Lymnaea stagnalis (L‐EGFR), and shown that L‐EGFR is the receptor for a previously identified EGF‐like peptide in Lymnaea, named Lymnaea EGF (L‐EGF). Knock‐down of L‐EGFR expression prevented L‐EGF‐induced excitatory synapse formation between identified cholinergic neuron visceral dorsal 4 (VD4) and its postsynaptic partner left pedal dorsal 1 (LPeD1). Moreover, knock‐down of L‐EGFR also prevented synapse formation induced by Lymnaea brain conditioned medium, suggesting that L‐EGF is the most important, if not the only, brain‐derived factor that promotes excitatory cholinergic synapse formation in Lymnaea. Thus, our data establish canonical EGF/EGFR signaling as an important synaptotrophic mechanism in invertebrates.
Invading populations of an ornamental shrub show rapid life history evolution despite genetic bottlenecks
Authors: Dlugosch Katrina M. , Parker Ingrid M. 
Published: April 2008

AbstractHuman‐mediated species introductions offer opportunities to investigate when and how non‐native species to adapt to novel environments, and whether evolution has the potential to contribute to colonization success. Many long‐established introductions harbour high genetic diversity, raising the possibility that multiple introductions of genetic material catalyze adaptation and/or the evolution of invasiveness. Studies of nascent invasions are rare but crucial for understanding whether genetic diversity facilitates population expansion. We explore variation and evolution in founder populations of the invasive shrubHypericum canariense. We find that these introductions have experienced large reductions in genetic diversity, but that increased growth and a latitudinal cline in flowering phenology have nevertheless evolved. These life history changes are consistent with predictions for invasive plants. Our results highlight the potential for even genetically depauperate founding populations to adapt and evolve invasive patters of spread.
The nature and reality of the aphid clone: genetic variation, adaptation and evolution
Authors: Loxdale Hugh D. 
Published: April 2008

Abstract1 When aphid clones and clonality are discussed, it is still often said that they are ‘genetically identical’, a statement for which there is no direct evidence, and certainly not for the entire genome. By contrast, there is a growing body of empirical data from the application of high resolution molecular (DNA) markers that aphid asexual lineages rapidly mutate and that, in some documented cases, this variation is selectable, either positively or negatively.2 Although it is true that, in enclosed conditions (e.g. laboratory or field cage), a so‐called clone as defined as the asexual progeny of a single foundress may be traceable, this is rarely if ever possible in the field without the use of genetic markers, and even then, usually only at a relatively few loci (multilocus genotypes, ‘MLGs’).3 The continued use of the term clone without qualification of its true nature and the reality of its interesting biology is likely to hamper a proper understanding of the ecology and evolution of these insects (which are interesting in their own right because of their complex life histories, but also because they are important as major pests globally, both by causing direct feeding damage and by transmitting pathogenic plant viruses and thereby leading to huge economic losses in the agricultural, horticultural and forestry industries).4 In this short review, I provide evidence of what is now known about aphid clonality after the widespread use of molecular markers, comprising information mainly gained within the last 15 years or so.5 The data demonstrate widespread adaptation and evolution, sometimes involving introgression and hybridization. Because of this new knowledge, our ideas of what constitutes a clone are in need of serious re‐evaluation.
Spatial and temporal dynamics of Myzus persicae clones in fields and suction traps
Authors: Kasprowicz Louise , Malloch Gaynor , Pickup Jon , Fenton Brian 
Published: April 2008

Abstract1 The population of peach‐potato aphid Myzus persicae in Scotland is comprised almost entirely of long‐term asexual clones.2 Over a ten year period, M. persicae from Scottish fields and suction traps were analysed with six microsatellite markers.3 Out of 1497 individuals analysed, 14 clones (denoted A–N) comprised over 98% of the collection.4 Some clones were particularly abundant but most clones had a widespread distribution on all available plants.5 Clones E and L had distinct features in their distributions as clone L was geographically totally restricted to the north east of Scotland and clone E showed a marked preference for brassica crops.6 Clones E and L provide direct evidence of a role for local adaptations in the distribution of M. persicae clones.
Spatial and temporal distribution of Empoasca vitis within a vineyard
Authors: Decante Damien , Van Helden Maarten 
Published: April 2008

Abstract1 The intra‐plot spatial distribution of the green leafhopper Empoasca vitis (Goethe) (Cicadellidae, Empoascini) was assessed over three successive growing seasons in a Bordeaux vineyard. Weekly measurements of adult trappings and nymphal counts were performed in a 1.7‐ha plot on 130 sampling points.2 Statistical and geostatistical analyses revealed inconsistent spatial distributions of adults and nymphs in spring, but consistent spatial distributions in summer, which were identical every year.3 Similarities between spatial distributions of the mobile adults and the sedentary and aggregated nymphs strongly suggest that adults disperse inside the plot to areas preferred for egg deposition.4 The similarity of summer populations among years suggests that this insects distribution is based on (perennial) differences in plot characteristics.
Histological verification of 11C‐choline‐positron emission/computed tomography‐positive lymph nodes in patients with biochemical failure after treatment for localized prostate cancer
Authors: Schilling David , Schlemmer Heinz P. , Wagner Philipp H. , Böttcher Patrick , Merseburger Axel S. , Aschoff Philip , Bares Roland , Pfannenberg Christa , Ganswindt Ute , Corvin Stefan , Stenzl Arnulf 
Published: April 2008

OBJECTIVESTo evaluate the potential of 11C‐choline‐positron emission tomography (PET)/computed tomography (CT) for planning surgery in patients with prostate cancer and prostate‐specific antigen (PSA) relapse after treatment with curative intent.PATIENTS AND METHODSWe retrospectively reviewed the charts of 10 patients with PSA recurrence after either external beam radiation (two) or radical retropubic prostatectomy (eight) for prostate cancer, and who had a laparoscopic lymphadenectomy for suspicious lymph nodes detected on 11C‐choline‐PET/CT. The histological results and PET/CT findings were compared.RESULTSIn all, 22 suspicious lymph nodes were found on PET/CT, and 14 on conventional CT or magnetic resonance imaging. Comparing the conventional imaging showed concordance in 13 lymph nodes. Three of the 10 patients had no metastatic lymph node disease on definitive histology. The mean (sd) PSA level for these patients was 1.0 (0.4) ng/mL, whereas that in patients with lymph node metastases was 15.1 (9.2) ng/mL (statistically significant difference, P < 0.05). The positive predictive value was seven of 10. All of the patients initially regressed, with PSA increases after lymphadenectomy. Two of the patients are being managed by watchful waiting, two had radiotherapy of the prostate fossa and two had chemotherapy with docetaxel. Four patients were treated by hormone‐deprivation therapy. After a mean (sd) follow up of 11 (7) months, one patient died, one has PSA progression, but none of those with negative histology has clinical signs of local recurrence.CONCLUSIONS 11C‐choline‐PET is a valuable tool for detecting recurrent prostate cancer, but the limited positive predictive value should lead to a critical interpretation of the results.
Evaluation of dynamic sentinel lymph node biopsy in patients with squamous cell carcinoma of the penis and palpable inguinal nodes
Authors: Heyns Chris F. , Theron Pieter D. 
Published: April 2008

OBJECTIVETo evaluate dynamic sentinel lymph node biopsy (DSLNB) in patients with squamous cell carcinoma (SCC) of the penis and palpable inguinal lymph nodes, using inguinal lymph node dissection (ILND) as the reference standard to assess the reliability of DSLNB, as using radioscintigraphy and colloidal blue‐dye injection to locate the SLN was reported to be a useful technique to avoid ILND in men with SCC of the penis and clinically impalpable nodes.PATIENTS AND METHODSThe study included 23 consecutive men with SCC of the penis and clinically palpable inguinal nodes treated between August 1999 and July 2006. On the day before surgery the patient had the SLN located by subcutaneous injection of 60 MBq 99mTc‐nanocolloid 2 cm proximal to the penile tumour. The following day the patient was taken to the operating room for DSLNB, resection of the penile tumour and simultaneous ILND, if considered indicated (G2‐3 and/or T3‐4 primary tumour). During surgery 2 mL of colloidal blue dye was injected in the same area as the previous 99mTc‐nanocolloid injection. The SLNs were located during surgery using a γ‐probe and visualization of blue dye in the node(s), which were then surgically removed. After partial or total penectomy, selected patients had ILND through a 10‐cm subinguinal incision. The primary tumour, SLNs and ILND specimens were assessed histopathologically, using haematoxylin and eosin staining only.RESULTSBiopsy of the primary tumour showed SCC grade 1 in six, grade 2 in 13 and grade 3 in two patients. The clinical T stage was T1 in two, T2 in seven, T3 in 13 and T4 in one. There were clinically palpable inguinal lymph nodes bilaterally in 19 and unilaterally in four men. Scintigraphy before surgery showed inguinal nodes bilaterally in 12 and unilaterally in eight patients, while there were no nodes in three. Surgery comprised partial penectomy in 14, radical penectomy in eight and circumcision alone in one patient. Simultaneous bilateral ILND was done in 15 patients. Inguinal node metastases were present in four of the 23 (17%) patients; the SLN was falsely negative in three (13%), one of whom had a small focus of cancer in the SLN that was missed on initial histopathological examination, and in two the dynamically located SLN contained no cancer, but node metastases were found in the ILND specimen.CONCLUSIONThe relatively high false‐negative rate of DSLNB indicates that it is not sufficiently reliable to replace complete ILND in men with a high suspicion of nodal metastases, i.e. a high‐grade or high‐stage primary lesion with clinically palpable inguinal nodes.
Changes to the contractile function of ureter smooth muscle after partial infravesical obstruction in fetal sheep
Authors: Nyirády Peter , Cuckow Peter M. , Fry Christopher H. 
Published: April 2008

OBJECTIVETo measure spontaneous contractile activity, and the responses to agonists using in vitro preparations of sheep ureter after a period of bladder outlet obstruction (BOO) initiated at mid‐gestation.MATERIAL AND METHODSDate‐mated Romney Marsh ewes, bearing fetuses of 70–75 days of gestation (term in this breed is 145 days) were used. Five fetuses underwent urachal obstruction and partial urethral constriction for 30 days. Six fetuses at the same gestational time underwent a sham operation (control group). Small strips of mid‐ureter were cut in the longitudinal axis, and in the cross‐sectional (transverse) plane of the ureter. Spontaneous contractile activity and the response to carbachol, high‐K+ (120 mm) solution and α,β‐methylene ATP (ABMA) were characterized by measuring the magnitude of evoked responses and the magnitude and frequency of spontaneous activity.RESULTSThe ureters from fetuses with BOO were significantly larger in diameter and had expanded lumens. The proportion of smooth muscle was not significantly different between the BOO and control groups. Spontaneous contractile activity in all preparations was resistant to atropine and the neurotoxin, tetrodotoxin. With transverse sections, the magnitude of spontaneous contractions was smaller in the BOO group, but the frequency was greater. The response to carbachol was also smaller in the BOO group, but the response to high‐K+ solution was similar to that of the control group. ABMA did not generate a response in any preparation. With longitudinal ureteric preparations, spontaneous or agonist‐induced activity was negligible in the control group, while preparations from the BOO sheep had spontaneous activity and responded to carbachol and high‐K+ solutions.CONCLUSIONThese results show that in fetuses with BOO and dilated ureters absolute ureteric contractile activity is diminished. However, there is functional reorganization of the muscle layers that generates more force in the longitudinal rather than the transverse axis. This would contribute to a reduced ability of the ureter to propel urine and contribute to the development of raised upper tract pressures.