bluuebunny/crossref_metadata_2025_split huggingface dataset:
Brain‐derived neurotrophic factor and neurotrophin receptors modulate glutamate‐induced phase shifts of the suprachiasmatic nucleus
Authors: Michel S. , Clark J. P. , Ding J. M. , Colwell C. S. 
Published: August 2006

AbstractLight information reaches the suprachiasmatic nucleus (SCN) through a subpopulation of retinal ganglion cells. Previous work raised the possibility that brain‐derived neurotrophic factor (BDNF) and its high‐affinity tropomyosin‐related receptor kinase may be important as modulators of this excitatory input into the SCN. In order to test this possibility, we used whole‐cell patch‐clamp methods to measure spontaneous excitatory currents in mouse SCN neurons. We found that the amplitude and frequency of these currents were increased by BDNF and decreased by the neurotrophin receptor inhibitor K252a. The neurotrophin also increased the magnitude of currents evoked by application of N‐methyl‐d‐aspartate and amino‐methyl proprionic acid. Next, we measured the rhythms in action potential discharge from the SCN brain slice preparation. We found that application of K252a dramatically reduced the magnitude of phase shifts of the electrical activity rhythm generated by the application of glutamate. By itself, BDNF caused phase shifts that resembled those produced by glutamate and were blocked by K252a. The results demonstrate that BDNF and neurotrophin receptors can enhance glutamatergic synaptic transmission within a subset of SCN neurons and potentiate glutamate‐induced phase shifts of the circadian rhythm of neural activity in the SCN.
Altered sodium currents in auditory neurons of congenitally deaf mice
Authors: Leão Richardson N. , Naves Marcell M. , Leão Katarina E. , Walmsley Bruce 
Published: August 2006

AbstractSodium currents are essential for action potential generation and propagation in most excitable cells. Appropriate tuning of these currents can be modulated both developmentally and in response to activity. Here we use a mouse model of congenital deafness (dn/dn– asymptomatic deafness associated with hair cell degeneration) to investigate the effect of lack of activity in the expression of Na+ currents in neurons from the medial nucleus of the trapezoid body (MNTB). Patch‐clamp recordings show that at postnatal day (P) 14, both normal and deaf mice display a significant amount of persistent and resurgent Na+ currents. However, the persistent current is greater in deaf mice than in normal mice, and resurgent current kinetics are slower in deaf mice. At P7, resurgent currents are not present in either group. MNTB immunohistochemistry demonstrates that Nav1.1 subunits are expressed postsynaptically in both P14 normal and deaf mice, while postsynaptic Nav1.6 staining was only observed in deaf mice. Labelling of Nav1.6 subunits in different age groups revealed that at younger ages (P7), both normal and deaf mice express this protein. Nav1.6 staining was not observed in MNTB neurons of P28 normal mice, whereas it is maintained in deaf mice cells until much later (P28). At P7, none of the groups displayed resurgent currents (despite the detection of Nav1.6 subunits at this age group); this suggests that factors other than alpha subunits are important for modulating these currents in MNTB cells. Our results emphasize the importance of activity during development in regulating Na+ channels.
Expression of a truncated tau protein induces oxidative stress in a rodent model of tauopathy
Authors: Cente Martin , Filipcik Peter , Pevalova Miroslava , Novak Michal 
Published: August 2006

AbstractTruncation of tau protein and oxidative stress have been implicated as important pathogenetic events in tauopathies including Alzheimer's disease (AD). We have generated a transgenic rat model that expresses a human truncated tau protein analogous to a variant form derived from sporadic AD. We employed this model to investigate the relationship between tau protein truncation and oxidative stress. We have found that rat cortical neurons (derived from transgenic animals) that had been cultured in vitro for 16 days showed an increased accumulation of reactive oxygen species (up to 1.4‐fold increase; P < 0.01) when compared to neurons derived from nontransgenic control animals. Transgene‐expressing neurons treated with inducers of oxidative stress, such as glucose oxidase (GO) and buthionine sulfoximine (BSO), displayed dramatically reduced survival (31.4 ± 3.3 and 24.9 ± 3.6%, respectively; both P < 0.001) compared to neurons from control animals (79.9 ± 7.1%, survival following treatment with GO and to 98.2 ± 3.8%, survival following treatment with BSO). The number of mitochondria in processes of neurons from transgenic animals was decreased by about one‐third from that present in neurons from control animals. The results reveal that expression of a human truncated variant form of tau protein leads to the accumulation of reactive oxygen species and sensitizes rat cortical neurons to cell death induced by oxidative stress. This indicates that truncation of tau may precede oxidative stress in the pathogenesis of neurodegenerative diseases such as AD and other tauopathies. These findings may have implications for therapeutic strategies aiming at prevention of neurofibrillary degeneration and cognitive decline, and identify potential new targets for drug development.
External tufted cells in the main olfactory bulb form two distinct subpopulations
Authors: Antal Miklós , Eyre Mark , Finklea Bryson , Nusser Zoltan 
Published: August 2006

AbstractThe glomeruli of the main olfactory bulb are the first processing station of the olfactory pathway, where complex interactions occur between sensory axons, mitral cells and a variety of juxtaglomerular neurons, including external tufted cells (ETCs). Despite a number of studies characterizing ETCs, little is known about how their morphological and functional properties correspond to each other. Here we determined the active and passive electrical properties of ETCs using in vitro whole‐cell recordings, and correlated them with their dendritic arborization patterns. Principal component followed by cluster analysis revealed two distinct subpopulations of ETCs based on their electrophysiological properties. Eight out of 12 measured physiological parameters exhibited significant difference between the two subpopulations, including the membrane time constant, amplitude of spike afterhyperpolarization, variance in the interspike interval distribution and subthreshold resonance. Cluster analysis of the morphological properties of the cells also revealed two subpopulations, the most prominent dissimilarity between the groups being the presence or absence of secondary, basal dendrites. Finally, clustering the cells taking all measured properties into account also indicated the presence of two subpopulations that mapped in an almost perfect one‐to‐one fashion to both the physiologically and the morphologically derived groups. Our results demonstrate that a number of functional and structural properties of ETCs are highly predictive of one another. However, cells within each subpopulation exhibit pronounced variability, suggesting a large degree of specialization evolved to fulfil specific functional requirements in olfactory information processing.
Transient synaptic zinc‐positive thalamocortical terminals in the developing barrel cortex
Authors: Ichinohe Noritaka , Potapov Daniel , Rockland Kathleen S. 
Published: August 2006

AbstractIn rat barrel cortex, layer 4 has a transiently high density of zinc‐positive terminations from postnatal day (P)9 to P12 [P.W. Land & L. Shamalla‐Hannah (2002)J. Comp. Neurol., 447, 43–56]. These terminations have been proposed to originate from cortico‐cortical connections, but their exact origin is unknown. To determine their sources, we injected sodium selenite into the barrel cortex of two adult rats and 32 pups, from P5 to P28. As predicted, abundant zinc‐positive cortically projecting neurons were visible around the injection sites and in distant cortical areas. From P9 to P13, however, neurons retrogradely labeled by zinc selenite occurred in the thalamus, in topographically appropriate regions of the ventroposterior medial (VPM) and posterior nuclei (Po). Because there are no previous reports of zinc‐positive sensory thalamocortical connections, we sought corroboration of this unexpected finding by electron microscopy. This revealed a subset of boutons in layers 4 and 1, positive for both zinc and vesicular glutamate transporter 2, a protein used by thalamocortical terminations. Finally, in an additional nine rats, we carried out in situ hybridization for zinc transporter 3 mRNA. Moderate signal was detected in VPM and Po at P10, but this disappeared by P28. In contrast, a strong signal was apparent in the anterodorsal nucleus, which projects to limbic areas, and this persisted at P28. The timing of the transient zinc‐positive terminations in the sensory thalamus roughly coincides with the onset of exploratory and whisking behavior in the middle of the second postnatal week; and this suggests zinc is important for activity‐related refinement of circuitry.
Quantifying the evidence for biodiversity effects on ecosystem functioning and services
Authors: Balvanera Patricia , Pfisterer Andrea B. , Buchmann Nina , He Jing‐Shen , Nakashizuka Tohru , Raffaelli David , Schmid Bernhard 
Published: August 2006

AbstractConcern is growing about the consequences of biodiversity loss for ecosystem functioning, for the provision of ecosystem services, and for human well being. Experimental evidence for a relationship between biodiversity and ecosystem process rates is compelling, but the issue remains contentious. Here, we present the first rigorous quantitative assessment of this relationship through meta‐analysis of experimental work spanning 50 years to June 2004. We analysed 446 measures of biodiversity effects (252 in grasslands), 319 of which involved primary producer manipulations or measurements. Our analyses show that: biodiversity effects are weaker if biodiversity manipulations are less well controlled; effects of biodiversity change on processes are weaker at the ecosystem compared with the community level and are negative at the population level; productivity‐related effects decline with increasing number of trophic links between those elements manipulated and those measured; biodiversity effects on stability measures (‘insurance’ effects) are not stronger than biodiversity effects on performance measures. For those ecosystem services which could be assessed here, there is clear evidence that biodiversity has positive effects on most. Whilst such patterns should be further confirmed, a precautionary approach to biodiversity management would seem prudent in the meantime.
Determining the identity and roles of oil‐metabolizing marine bacteria from the Thames estuary, UK
Authors: McKew Boyd A. , Coulon Frédéric , Osborn A. Mark , Timmis Kenneth N. , McGenity Terry J. 
Published: August 2006

SummaryCrude oil is a complex mixture of different hydrocarbons. While diverse bacterial communities can degrade oil, the specific roles of individual members within such communities remain unclear. To identify the key bacterial taxa involved in aerobic degradation of specific hydrocarbons, microcosm experiments were established using seawater from Stanford le Hope, Thames estuary, UK, adjacent to a major oil refinery. In all microcosms, hydrocarbon degradation was significant within 10 weeks, ranging from > 99% of low‐molecular‐weight alkanes (C10–C18), 41–84% of high‐molecular‐weight alkanes (C20–C32) and pristane, and 32–88% of polycyclic aromatic hydrocarbons (PAHs). Analysis of 16S rRNA sequences from clone libraries and denaturing gradient gel electrophoresis (DGGE) indicated that, except when incubated with fluorene, PAH‐degrading communities were dominated by Cycloclasticus. Moreover, PAH‐degrading communities were distinct from those in microcosms containing alkanes. Degradation of the branched alkane, pristane, was carried out almost exclusively by Alcanivorax. Bacteria related to Thalassolituus oleivorans (99–100% identity) were the dominant known alkane degraders in n‐alkane (C12–C32) microcosms, while Roseobacter‐related bacteria were also consistently found in these microcosms. However, in contrast to previous studies, Thalassolituus, rather than Alcanivorax, was dominant in crude oil‐enriched microcosms. The communities in n‐decane microcosms differed from those in microcosms supplemented with less volatile alkanes, with a phylogenetically distinct species of Thalassolituus out‐competing T. oleivorans. These data suggest that the diversity and importance of the genus Thalassolituus is greater than previously established. Overall, these experiments demonstrate how degradation of different petroleum hydrocarbons is partitioned between different bacterial taxa, which together as a community can remediate petroleum hydrocarbon‐impacted estuarine environments.
Effects of temperature and biostimulation on oil‐degrading microbial communities in temperate estuarine waters
Authors: Coulon Frédéric , McKew Boyd A. , Osborn A. Mark , McGenity Terry J. , Timmis Kenneth N. 
Published: August 2006

SummaryImproved strategies for oil‐spill remediation will follow a better understanding of the nature, activities and regulating parameters of petroleum hydrocarbon‐degrading microbial communities in temperate marine environments. The addition of crude oil to estuarine water resulted in an immediate change in bacterial community structure, increased abundance of hydrocarbon‐degrading microorganisms and a rapid rate of oil degradation, suggesting the presence of a pre‐adapted oil‐degrading microbial community and sufficient supply of nutrients. Relatively rapid degradation was found at 4°C, the lowest temperature tested; and it was temperature rather than nutrient addition that most influenced the community structure. A detailed phylogenetic analysis of oil‐degrading microcosms showed that known hydrocarbonoclastic organisms like Thalassolituus and Cycloclasticus, as well as proposed oil degraders like Roseobacter, were present at both 4°C and 20°C, demonstrating the thermo‐versatility of such organisms. Clones related to Oleispira antarctica (98% 16S rRNA similarity), a psychrophilic alkane degrader, were dominant in the 4°C oil‐degrading community, whereas other clones constituting a different clade and showing 94% similarity 16S rRNA with O. antarctica were found in situ. These findings demonstrate the potential for intrinsic bioremediation throughout the course of the year in temperate estuarine waters, and highlight the importance of both versatile psychrotolerant and specialized psychrophilic hydrocarbon‐degrading microbes in effecting this process at low temperatures.
A prospective evaluation of occult disorders in obstructed defecation using the ‘iceberg diagram’
Authors: Pescatori M. , Spyrou M. , Pulvirenti d'Urso A. 
Published: August 2006

AbstractObjective  Surgical treatment of constipation and obstructed defecation (OD) carries frequent recurrences, as OD is an ‘iceberg syndrome’ characterized by ‘underwater rocks’ or occult diseases which may affect the outcome of surgery. The aim of this study was to evaluate occult disorders, in order to alert the clinician of these and minimize failures.Method  One hundred consecutive constipated patients with OD symptoms, 81 women, median age 52 years, underwent perineal examination, proctoscopy, anorectal manometry and anal/vaginal ultrasound (US). Anorectal physiology and imaging tests were also carried out when indicated, as well as psychological and urogynaecological consultations. Symptoms were graded using a modified 1–20 constipation score. Both evident (e.g. rectocele) and occult (e.g. anismus) diseases were prospectively evaluated using a novel ‘iceberg diagram’. The type of treatment, whether conservative or surgical, was also recorded.Results  Fifty‐four (54%) patients had both mucosal prolapse and rectocele. All patients had at least two occult OD‐related diseases, 66 patients had at least three of them: anxiety–depression, anismus and rectal hyposensation were the most frequent (66%, 44% and 33%, respectively). The median constipation score was 11 (range 2–20), the median number of ‘occult disorders’ was 5 (range 2–8). Conservative treatment was carried out in most cases. Surgery was carried out in 14 (14%) patients.Conclusion  The novel ‘iceberg diagram’ allowed the adequate evaluation of OD‐related occult diseases and better selection of patients for treatment. Most were managed conservatively, and only a minority were treated by surgery.
Acute hyperglycaemia does not alter coronary vascular function in isolated, perfused rat hearts
Authors: Klabunde R. E. , Ryan K. M. , Paxson C. E. 
Published: August 2006

Aim:  The purpose of this study was to evaluate the hypothesis that acute hyperglycaemia in hearts of rats without diabetes alters coronary vascular responses to nitric oxide (NO), adenosine (ADO) and phenylephrine (PHE).Methods:  Coronary function was studied in isolated, Langendorff‐perfused, non‐beating rat hearts that were perfused with an oxygenated Krebs–Henseleit solution containing 40 mM KCl to arrest the hearts. Changes in coronary vascular resistance were assessed by measuring changes in coronary perfusion pressure under constant flow conditions. Coronary responses to ADO, sodium nitroprusside (SNP), PHE and L‐NAME (inhibitor of NO synthase) were studied either under normoglycaemic conditions (100 mg/dl d‐glucose) or after 60 min of hyperglycaemic perfusion (500 mg/dl d‐glucose). d‐mannitol was used as a hyperosmotic control.Results:  Hyperglycaemia did not alter vasodilator responses to ADO or SNP in the presence or absence of L‐NAME. Furthermore, hyperglycaemia, compared with normoglycaemia, did not alter vasoconstrictor responses induced by L‐NAME or PHE.Conclusions:  Sixty minutes of exposure to 500 mg/dl of d‐glucose in an isolated, non‐beating, buffer‐perfused rat heart did not significantly affect coronary vascular smooth muscle vasodilator responses to NO and ADO or alter α1‐adrenoceptor‐mediated vasoconstrictor responses to PHE. Furthermore, an unchanged vasoconstrictor response to L‐NAME suggests that acute hyperglycaemia did not alter NO bioavailability.
Spectrum of Mutations in the CFTR Gene in Cystic Fibrosis Patients of Spanish Ancestry
Authors: Alonso M. J. , Heine‐Suñer D. , Calvo M. , Rosell J. , Giménez J. , Ramos M. D. , Telleria J. J. , Palacio A. , Estivill X. , Casals T. 
Published: August 2006

SummaryWe analyzed 1,954 Spanish cystic fibrosis (CF) alleles in order to define the molecular spectrum of mutations in the CFTR gene in Spanish CF patients. Commercial panels showed a limited detection power, leading to the identification of only 76% of alleles. Two scanning techniques, denaturing gradient gel electrophoresis (DGGE) and single strand conformation polymorphism/hetroduplex (SSCP/HD), were carried out to detect CFTR sequence changes. In addition, intragenic markers IVS8CA, IVS8‐6(T)n and IVS17bTA were also analyzed. Twelve mutations showed frequencies above 1%, p.F508del being the most frequent mutation (51%). We found that eighteen mutations need to be studied to achieve a detection level of 80%. Fifty‐one mutations (42%) were observed once. In total, 121 disease‐causing mutations were identified, accounting for 96% (1,877 out of 1,954) of CF alleles. Specific geographic distributions for the most common mutations, p.F508del, p.G542X, c.1811 + 1.6kbA > G and c.1609delCA, were confirmed. Furthermore, two other relatively common mutations (p.V232D and c.2789 + 5G > A) showed uneven geographic distributions. This updated information on the spectrum of CF mutations in Spain will be useful for improving genetic testing, as well as to facilitate counselling in people of Spanish ancestry. In addition, this study contributes to defining the molecular spectrum of CF in Europe, and corroborates the high molecular mutation heterogeneity of Mediterranean populations.
Attentional blink and prepulse inhibition of startle are positively correlated
Authors: Cornwell Brian R. , Echiverri Aileen M. , Grillon Christian 
Published: August 2006

AbstractAlthough a link between the attentional blink and prepulse startle inhibition has been considered, no evidence of this relationship has been reported. We delivered acoustic startle probes during rapid serial visual presentations in which the relative positions of two targets (targets 1 and 2) was varied within a stream of distractors. Startle probes were presented at 100 ms lead intervals relative to onset of a target or distractor. We found positive correlations between visual prepulse inhibition and attentional blink effects across participants. As the magnitude of prepulse inhibition with target and distractor lead stimuli increased, deficits in identifying target 2 during the attentional blink increased, suggesting similar processes underlying these phenomena. Whereas prepulse inhibition may reveal the strength of inhibition to protect stimulus processing, attentional blink may index the rate of recovery from similar inhibitory processes.
Electromyographic responses to static and dynamic avatar emotional facial expressions
Authors: Weyers Peter , Mühlberger Andreas , Hefele Carolin , Pauli Paul 
Published: August 2006

AbstractFacial muscular reactions to avatars' static (neutral, happy, angry) and dynamic (morphs developing from neutral to happy or angry) facial expressions, presented for 1 s each, were investigated in 48 participants. Dynamic expressions led to better recognition rates and higher intensity and realism ratings. Angry expressions were rated as more intense than happy expressions. EMG recordings indicated emotion‐specific reactions to happy avatars as reflected in increased M. zygomaticus major and decreased M. corrugator supercilii tension, with stronger reactions to dynamic as compared to static expressions. Although rated as more intense, angry expressions elicited no significant M. corrugator supercilii activation. We conclude that facial reactions to angry and to happy facial expressions hold different functions in social interactions. Further research should vary dynamics in different ways and also include additional emotional expressions.
Nerve growth factor‐induced phosphorylation of amphiphysin‐1 by casein kinase 2 regulates clathrin–amphiphysin interactions
Authors: Döring Markus , Loos Anneke , Schrader Nina , Pfander Boris , Bauerfeind Rudolf 
Published: August 2006

AbstractAmphiphysins interact directly with clathrin and have a function in clathrin‐mediated synaptic vesicle recycling and clathrin‐mediated endocytosis. The neuronal isoform amphiphysin‐1 is a serine/threonine phosphoprotein that is dephosphorylated upon stimulation of synaptic vesicle endocytosis. Rephosphorylation was stimulated by nerve growth factor. We analysed the regulation of amphiphysin–clathrin interactions by phosphorylation. The N‐terminal domain of clathrin bound to unphosphorylated amphiphysin‐1, but not to the phosphorylated protein. A search for possible phosphorylation sites revealed two casein kinase 2 consensus motifs in close proximity to the clathrin binding sites in amphiphysin‐1 and ‐2. We mutagenized these residues (T350 and T387) to glutamate, mimicking a constitutive phosphorylation. The double mutant showed a strong reduction in clathrin binding. The assumption that casein kinase 2 phosphorylates amphiphysin‐1 at T350 and T387 was corroborated by experiments showing that: (i) casein kinase 2 phosphorylated these residues directly in vitro, (ii) when expressed in HeLa cells, the glutamate mutant showed reduced phosphorylation, and (iii) casein kinase 2 inhibitors blocked nerve growth factor‐induced phosphorylation of endogenous amphiphysin‐1 in PC12 cells. These observations are consistent with the hypothesis that, upon activation by nerve growth factor, casein kinase 2 phosphorylates amphiphysin‐1 and thereby regulates the endocytosis of clathrin‐coated vesicles via the interaction between clathrin and amphiphysin.