bluuebunny/crossref_metadata_2025_split huggingface dataset:
Small‐world network topology of hippocampal neuronal network is lost, in an in vitro glutamate injury model of epilepsy
Authors: Srinivas Kalyan V. , Jain Rishabh , Saurav Subit , Sikdar Sujit K. 
Published: June 2007

AbstractNeuronal network topologies and connectivity patterns were explored in control and glutamate‐injured hippocampal neuronal networks, cultured on planar multielectrode arrays. Spontaneous activity was characterized by brief episodes of synchronous firing at many sites in the array (network bursts). During such assembly activity, maximum numbers of neurons are known to interact in the network. After brief glutamate exposure followed by recovery, neuronal networks became hypersynchronous and fired network bursts at higher frequency. Connectivity maps were constructed to understand how neurons communicate during a network burst. These maps were obtained by analysing the spike trains using cross‐covariance analysis and graph theory methods. Analysis of degree distribution, which is a measure of direct connections between electrodes in a neuronal network, showed exponential and Gaussian distributions in control and glutamate‐injured networks, respectively. Although both the networks showed random features, small‐world properties in these networks were different. These results suggest that functional two‐dimensional neuronal networks in vitro are not scale‐free. After brief exposure to glutamate, normal hippocampal neuronal networks became hyperexcitable and fired a larger number of network bursts with altered network topology. The small‐world network property was lost and this was accompanied by a change from an exponential to a Gaussian network.
Disruption of reelin signaling attenuates methamphetamine‐induced hyperlocomotion
Authors: Matsuzaki Hideo , Minabe Yoshio , Nakamura Kazuhiko , Suzuki Katsuaki , Iwata Yasuhide , Sekine Yoshimoto , Tsuchiya Kenji J. , Sugihara Genichi , Suda Shiro , Takei Nori , Nakahara Daiichiro , Hashimoto Kenji , Nairn Angus C. , Mori Norio , Sato Kohji 
Published: June 2007

AbstractTo clarify whether reelin signaling is involved in dopaminergic neurotransmission in the adult mouse brain, we investigated dopamine function in mice lacking reelin (reeler). We found that methamphetamine‐induced locomotor activity is significantly attenuated in reeler mice. To elucidate the mechanism of this phenomenon, we first investigated presynaptic dopamine release; however, there were no significant differences in wildtype, heterozygous reeler and homozygous reeler mice. Next, we examined the locomotor response to intra‐accumbens injection of dopamine D1 and D2 receptor agonists, and found that lack of reelin signaling results in decreases in both D1 and D2 receptor‐mediated dopaminergic functions. In addition, we measured dopamine receptor binding in the striatum, and found that both D1 and D2 classes of dopamine receptors are reduced in reeler mice. Furthermore, we found that the phosphorylation levels of DARPP‐32 are also changed by lack of reelin signaling. Finally, to distinguish between a developmental role of reelin or an acute role of reelin in adult mouse, we intraventricularly infused CR‐50, a monoclonal antibody against reelin. Interestingly, infusion of CR‐50 also significantly reduced methamphetamine‐induced hyperlocomotion in wildtype mice, showing that reelin has an acute role in the dopaminergic system. These results indicate that reelin signaling plays a pivotal role in the dopaminergic system in adult mice, especially in postsynaptic levels.
Brainstem cholinergic modulation of muscle tone in infant rats
Authors: Gall Andrew J. , Poremba Amy , Blumberg Mark S. 
Published: June 2007

AbstractIn week‐old rats, lesions of the dorsolateral pontine tegmentum (DLPT) and nucleus pontis oralis (PnO) have opposing effects on nuchal muscle tone. Specifically, pups with DLPT lesions exhibit prolonged bouts of nuchal muscle atonia (indicative of sleep) and pups with PnO lesions exhibit prolonged bouts of high nuchal muscle tone (indicative of wakefulness). Here we test the hypothesis that nuchal muscle tone is modulated, at least in part, by cholinergically mediated interactions between these two regions. First, in unanesthetized pups, we found that chemical infusion of the cholinergic agonist carbachol (22 mm, 0.1 µL) within the DLPT produced high muscle tone. Next, chemical lesions of the PnO were used to produce a chronic state of high nuchal muscle tone, at which time the cholinergic antagonist scopolamine (10 mm, 0.1 µL) was infused into the DLPT. Scopolamine effectively decreased nuchal muscle tone, thus suggesting that lesions of the PnO increase muscle tone via cholinergic activation of the DLPT. Using 2‐deoxyglucose autoradiography, metabolic activation throughout the DLPT was observed after PnO lesions. Finally, consistent with the hypothesis that PnO inactivation produces high muscle tone, infusion of the sodium channel blocker lidocaine (2%) into the PnO of unanesthetized pups produced rapid increases in muscle tone. We conclude that, even early in infancy, the DLPT is critically involved in the regulation of muscle tone and behavioral state, and that its activity is modulated by a cholinergic mechanism that is directly or indirectly controlled by the PnO.
Group I metabotropic glutamate receptors enable two distinct forms of long‐term depression in the rat dentate gyrusin vivo
Authors: Naie Katja , Tsanov Marian , Manahan‐Vaughan Denise 
Published: June 2007

AbstractThe existence of long‐term depression (LTD) in the dentate gyrus of freely moving rats, as well as the contribution of different types of metabotropic glutamate receptors (mGluRs) to this form of plasticity, has been the subject of much debate. Here, we describe two distinct forms of mGluR‐dependent hippocampal LTD in the dentate gyrus of freely moving adult rats. LTD, induced by low‐frequency stimulation (LFS) of the medial perforant path (LFS‐LTD), was prevented by antagonism of the phospholipase C‐coupled receptors, mGluR1 but not mGluR5. Chemical LTD, induced by intracerebral application of the group I mGluR agonist (R,S)‐3,5‐dihydroxyphenylglycine, was blocked by antagonism of both mGluR5 and mGluR1. Selective activation of mGluR5, using (R,S)‐2‐chloro‐5‐hydroxyphenylglycine (CHPG), also led to chemical LTD. To test whether LFS‐LTD and chemical LTD share common induction mechanisms, we applied LFS following the induction of chemical LTD by CHPG (CHPG‐LTD). Surprisingly, LFS impaired CHPG‐LTD. Further analysis revealed that induction of CHPG‐LTD led to altered calcium dynamics sufficient for its reversal by LFS. We found that LTD induced by (R,S)‐3,5‐dihydroxyphenylglycine, but not by CHPG, is impaired byN‐methyl‐d‐aspartate receptor antagonism. Both forms of chemical LTD strongly require calcium influx throughL‐type voltage‐gated calcium channels. This contrasts with previous findings that LFS‐LTD in the dentate gyrus is bothN‐methyl‐d‐aspartate receptor and voltage‐gated calcium channel independent. LFS‐LTD and LTD induced by group I mGluR agonists thus appear to comprise distinct forms of LTD that require the activation of specific group I mGluRs and recruit calcium from different sources.
Individual differences in the effects of chronic prazosin hydrochloride treatment on hippocampal mineralocorticoid and glucocorticoid receptors
Authors: Kabbaj Mohamed , Morley‐Fletcher Sara , Le Moal Michel , Maccari Stefania 
Published: June 2007

AbstractThe aim of this study was to investigate the noradrenergic regulation of mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) in high responder (HR) and low responder (LR) male rats, an animal model of individual differences in hypothalamo‐pituitary‐adrenal axis activity and vulnerability to drugs of abuse. The effects of a chronic treatment with the noradrenergic α1 antagonist (1‐[4‐amino‐6,7‐dimethoxy‐2‐quinazolinyl]‐4‐[2‐furanylcarbonyl] piperazine) hydrochloride (prazosin) (0.5 mg/kg, i.p., 35 days) were assessed on stress‐induced corticosterone (CORT) secretion and on hippocampal MRs and GRs in adrenally intact rats. In order to ascertain whether the effects of chronic prazosin treatment on hippocampal MRs and GRs were direct or indirect, through prazosin‐induced CORT secretion, we also assessed the effects of the same treatment on adrenalectomized rats with CORT substitutive therapy. When compared with LR rats, HR rats exhibited a delayed return to the basal level of CORT following acute restraint stress; this was associated with a lower binding of MRs and GRs in HR rats than in LR rats. Chronic prazosin treatment had no effect in HR animals but markedly reduced hippocampal MRs and GRs, and increased stress‐induced CORT secretion in LR rats. In LR adrenalectomized rats, prazosin reduced hipppocampal MRs but did not change GRs. Our results provide evidence of a differential regulation by noradrenaline of hippocampal MRs and GRs in HR and LR rats. These data could have clinical implications in terms of individual differences in the resistance to antidepressant treatments and individual differences in drug abuse.
No improvement by amphetamine on learned non‐use, attempts, success or movement in skilled reaching by the rat after motor cortex stroke
Authors: Alaverdashvili Mariam , Lim Diana H. , Whishaw Ian Q. 
Published: June 2007

AbstractAmphetamine (AMPH) has been proposed as a treatment for post‐stroke motor deficits when coupled with symptom‐relevant physical rehabilitation. Whereas a number of experimental studies report improvements in endpoint measures of skilled reaching for food by rats, there has been no assessment of whether beneficial effects extend to overcoming learned non‐use of the limb in the acute post‐stroke period or to the qualitative deficits in movement in the chronic post‐stroke period. In addition to evaluating the effects of AMPH on success, these were the objectives of the present study. In three different reaching experiments, groups of rats were pre‐trained in skilled reaching for food prior to receiving a motor cortex stroke via pial removal. Postoperatively the rats received periodic AMPH treatment and daily rehabilitation. In the acute post‐stroke period, AMPH failed to prevent the development of learned non‐use of the limb, and in the acute and chronic period failed to improve recovery of reaching success, and also failed to improve the qualitative aspects of reaching movements. Nevertheless, AMPH did enhance adjunct non‐reaching movements of locomotion, rearing and turning. The results are discussed in relation to the idea that the beneficial effects of post‐stroke AMPH treatment do not extend to all movements, especially the movements of a forelimb in retrieving and consuming food.
Decreased motivation to eat in µ‐opioid receptor‐deficient mice
Authors: Papaleo Francesco , Kieffer Brigitte L. , Tabarin Antoine , Contarino Angelo 
Published: June 2007

AbstractAltered motivational processes might participate to the physiopathology of eating‐related disorders. The endogenous opioid system is thought to mediate the hedonic properties of food intake. To assess the role for the µ‐opioid receptor (MOR) pathway in the motivational properties of food intake, in the present study we tested wild‐type and MOR‐deficient mice (MOR–/–) in a nose‐poke operant paradigm for chow or sucrose pellets. To avoid confounding factors linked to food restriction/deprivation experience, mice were always provided with foodad libitum. Although less MOR–/– than wild‐type mice initiated operant behaviour, under a fixed ratio‐1 (FR‐1) reinforcement schedule the two genotypes showed similar patterns of food‐driven nose‐poking, indicating preserved cognitive abilities in MOR‐deficient mice. However, during FR‐3 and progressive ratio (PR) reinforcement experiments, MOR–/– mice showed lower levels of nose‐poking for either chow or sucrose pellets than wild‐type mice, indicating a crucial role for the MOR pathway in the motivational properties of food intake. Moreover, under the PR reinforcement schedule mice nose‐poking for sucrose pellets showed higher genotype‐independent breakpoint levels than mice working for chow pellets, indicating that the MOR pathway is not essential for hedonic processing of palatable food intake. Finally, MOR–/– mice did not differ from wild‐type mice in the rate of operant responding extinction, further supporting the notion of unaltered cognitive abilities in the MOR‐deficient mice. The present findings strongly indicate that the MOR pathway mediates the motivational properties of food intake, but it is not essential for hedonic processing of ingestive behaviour.
Role of the midbrain dopaminergic system in modulation of vocal brain activation by social context
Authors: Hara Erina , Kubikova Lubica , Hessler Neal A. , Jarvis Erich D. 
Published: June 2007

AbstractIn a well‐studied model of social behaviour, male zebra finches sing directed song to court females and undirected song, used possibly for practice or advertisement. Although the two song types are similar, the level of neural activity and expression of the immediate early geneegr‐1are higher during undirected than during directed singing in the lateral part of the basal ganglia song nucleus AreaX (LAreaX) and its efferent pallial song nuclei lateral magnocellular nucleus of the anterior nidopallium (LMAN) and the robust nucleus of the arcopallium (RA). As social interactions are dependent on brain motivation systems, here we test the hypothesis that the midbrain ventral tegmental area–substantia nigra pars compacta (VTA–SNc) complex, which provides a strong dopaminergic input to LAreaX, is a source of this modulation. Usingegr‐1expression, we show that GABAergic interneurons in VTA–SNc are more active during directed courtship singing than during undirected singing. We also found that unilateral removal of VTA–SNc input reduced singing‐dependent gene expression in ipsilateral LAreaX during both social contexts but it did not eliminate social context differences in LAreaX. In contrast, such lesions reduced and eliminated the social context differences in efferent nuclei LMAN and RA, respectively. These results suggest that VTA–SNc is not solely responsible for the social context gene regulation in LAreaX, but that VTA–SNc input to LAreaX enhances the singing‐regulated gene expression in this nucleus and, either through LAreaX or through direct projections to LMAN and RA, VTA–SNc is necessary for context‐dependent gene regulation in these efferent nuclei.
Disgust sensitivity predicts the insula and pallidal response to pictures of disgusting foods
Authors: Calder Andrew J. , Beaver John D. , Davis Matt H. , Van Ditzhuijzen Jenneke , Keane Jill , Lawrence Andrew D. 
Published: June 2007

AbstractThe anterior insula has been implicated in coding disgust from facial, pictorial and olfactory cues, and in the experience of this emotion. Personality research has shown considerable variation in individuals' trait propensity to experience disgust (‘disgust sensitivity’). Our study explored the neural expression of this trait, and demonstrates that individual variation in disgust sensitivity is significantly correlated with participants' ventroanterior insular response to viewing pictures of disgusting, but not appetizing or bland, foods. Similar correlations were also seen in the pallidum and orofacial regions of motor and somatosensory cortices. Our results also accord with comparative research showing an anterior to posterior gradient in the rat pallidum reflecting increased ‘liking’ of foods [Smith, K. S. and Berridge, K. C. (2005) J. Neurosci., 25, 849–8637].
Bacteriophage influence Campylobacter jejuni types populating broiler chickens
Authors: Scott Andrew E. , Timms Andrew R. , Connerton Phillippa L. , El‐Shibiny Ayman , Connerton Ian F. 
Published: June 2007

SummaryThe characteristics that allow one Campylobacter jejuni genotype to succeed over another under the influence of bacteriophage predation have been examined in experimental broiler chickens following the observation that this succession appeared to occur in naturally colonized broiler chicken flocks. Examination of three C. jejuni strains from a single flock indicated that horizontal transfer of at least 112 kb of genomic DNA from strain F2C10 (bacteriophage sensitive) to strain F2E1 (bacteriophage insensitive) had created strain F2E3. Transfer of this DNA was associated with acquisition of sensitivity to 6 of 25 lytic bacteriophage isolated from the same flock. All strains tested were capable of colonizing broiler chickens but cocolonization revealed that the bacteriophage sensitive strains F2E3 and F2C10 had a competitive advantage over the bacteriophage insensitive strain F2E1. With the addition of lytic bacteriophage the situation was completely reversed, with F2E1 dominating. The inability to replicate bacteriophage is associated with a significant fitness cost that renders the insensitive strain competitive only in the presence of bacteriophage. We demonstrate that interstrain recombination in vivo can generate genome diversity in C. jejuni and that bacteriophage predation is a strong selective pressure that influences the relative success of emergent strains in broiler chickens.
Rapid growth rates of aerobic anoxygenic phototrophs in the ocean
Authors: Koblížek Michal , Mašín Michal , Ras Josephine , Poulton Alex J. , Prášil Ondřej 
Published: June 2007

SummaryWe analysed bacteriochlorophyll diel changes to assess growth rates of aerobic anoxygenic phototrophs in the euphotic zone across the Atlantic Ocean. The survey performed during Atlantic Meridional Transect cruise 16 has shown that bacteriochlorophyll in the North Atlantic Gyre cycles at rates of 0.91–1.08 day−1 and in the South Atlantic at rates of 0.72–0.89 day−1. In contrast, in the more productive equatorial region and North Atlantic it cycled at rates of up to 2.13 day−1. These results suggest that bacteriochlorophyll‐containing bacteria in the euphotic zone of the oligotrophic gyres grow at rates of about one division per day and in the more productive regions up to three divisions per day. This is in striking contrast with the relatively slow growth rates of the total bacterial community. Thus, aerobic anoxygenic phototrophs appear to be a very dynamic part of the marine microbial community and due to their rapid growth, they are likely to be larger sinks for dissolved organic matter than their abundance alone would predict.
The increasing use of intravesical therapies for stage T1 bladder cancer coincides with decreasing survival after cystectomy
Authors: Lambert Erica H. , Pierorazio Phillip M. , Olsson Carl A. , Benson Mitchell C. , McKiernan James M. , Poon Steven 
Published: June 2007

OBJECTIVEIntravesical therapy (IVT), chemo and immunotherapy, has made conservative, bladder‐sparing strategies a viable option for managing patients with high grade T1 bladder cancer. However, many of these patients will have recurrence and occasionally progression, questioning delayed intervention. This study examines the patterns of use of IVT in high‐grade T1 bladder cancer and the subsequent impact on survival for patients ultimately proceeding to radical cystectomy (RC).PATIENTS AND METHODSBetween 1990 and 2005, 104 patients were identified with T1 high‐grade transitional cell carcinoma (TCC) and who underwent RC. Patients were divided into two groups; those having RC before 1998 (median year of surgery) and those after 1998. Trends in time from diagnosis to RC, courses of IVT, recurrence and pathological stage were analysed using two‐sample t‐tests with 95% confidence intervals. Kaplan–Meier analysis was used to determine the disease‐free and overall survival rates.RESULTSBefore 1998, 28 of 38 patients (74%) proceeded directly to RC with no IVT, vs 20 of 47 (43%) after 1998 (P = 0.004). The mean number of IVT courses per patient was 0.53 before 1998 and 1.2 afterward (P = 0.016). Patients who had RC before 1998 had a 69.7% disease‐free survival at 5 years, vs 39.6% for those after 1998 (P = 0.05).CONCLUSIONIn the past 15 years, our experience indicates that patients having RC for T1 high‐grade TCC after 1998 were more likely to receive IVT. These same patients had a worsening disease‐free survival. In very few other cancers has disease‐free survival decreased over time. We postulate that the decrease in survival might be related to an increased use of IVT.
Intrarenal manipulation of flexible ureteroscopes: a comparative study
Authors: Monga Manoj , Weiland Derek , Pedro Renato N. , Lynch Alexandria C. , Anderson Kyle 
Published: June 2007

OBJECTIVETo compare the relative ease of manipulation around a calyceal model in the hands of experienced ureteroscopists of four flexible ureteroscopes (FUs), as new‐generation FUs provide exaggerated active deflection to facilitate intrarenal manipulation.SUBJECTS AND METHODSFour FUs of <7.5 F were tested: the FlexVision U‐500 (SF) (Stryker Endoscopy, San Jose, CA, USA), the Dur‐8 Elite (D8E) (ACMI, Southborough, MA, USA), the Viper (Richard Wolf Medical Instruments, Vernon Hills, IL, USA) and the URF‐P3 (Olympus Surgical, Orangeburg, NY, USA). Eight experienced ureteroscopists, each with a minimum of 100 flexible ureteroscopies over the preceding 3 years, assessed the FUs. The Mediskills calyceal model represents a moderately hydronephrotic collecting system, with a renal pelvic width of 2 cm, infundibular widths of 1 cm and infundibular lengths of 2 cm. The middle calyx infundibular angle was 80° and the lower calyx infundibular angle was 100°. The model does not allow for significant passive secondary deflection. The surgeons manoeuvred systematically around a four‐point course, from the pelvi‐ureteric junction, to anterior lower calyx, to anterior middle calyx, to posterior lower calyx, to posterior middle calyx, touching a metal sensor with an fulguration electrode, to trigger an automated signal at each calyx. The order of FU used by each surgeon was randomized. Each surgeon performed the course twice with each FU, ending with the first FU they started with, to diminish the impact of ‘learning the course’.RESULTSThere were significant differences in the mean (sd) total time for manipulation through the four‐point course, for the Viper, SF, D8E and URF‐P3, at 29 (11), 37 (23), 38 (20) and 50 (24) s, respectively (P = 0.034). The URF‐P3 took longer to reach the posterior lower pole, at 18.1 (14.5) s than the Viper, SF and D8E, at 6.3 (2.8) (P = 0.004), 6.6 (3.3) (P = 0.008) and 7.7 (4.9) (P = 0.008), respectively. The Viper was quicker to reach the posterior middle pole, at 7.3 (4.0) s, than the URF‐P3, SF and D8E, at 14.9 (13.1) (P = 0.036), 14.7 (14.3) (P = 0.056) and 12.7 (14.0) s (P = 0.115), respectively. Subjectively, six of eight endoscopists stated that the Viper was the better FU for ease of manipulation, while five of eight stated that the URF‐P3 was the most difficult. Notably, all eight endoscopists had more clinical experience with the URF‐P3 than with the other three FUs tested.CONCLUSIONSIn a model of a moderately hydronephrotic kidney with long infundibulum and limited ability to perform passive secondary deflection, FUs with exaggerated active deflection outmanoeuvred the URF‐P3. The Viper was better for manipulation in the hands of experienced endoscopists.