bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrophysiological and neurochemical study of the rat geniculo‐cortical pathway. Evidence for glutamatergic neurotransmission
Authors: Sáez J. A. , Palomares J. M. , Vives F. , Domínguez I. , Villegas I. , Montes R. , Price D. J. , Ferrer J. M. R. 
Published: December 2004

AbstractThe projection from the dorsal lateral geniculate nucleus to the primary visual cortex of the rat was studied electrophysiologically. Electrical stimulation of the dorsal lateral geniculate nucleus and the optic tract produced three types of responses on neurons of area 17: excitation followed by inhibition, excitation and inhibition. These results extend and confirm, in adult rats, previous studies done in rat geniculate‐visual cortex cocultures preparations in vitro. The role of glutamate in the neurotransmission of the rat geniculo‐cortical pathway was also investigated. In a first set of experiments, the effects of kynurenate, an antagonist of glutamate receptors, on visual cortex neurons with a monosynaptic excitatory response to dorsal lateral geniculate nucleus stimulation were studied. Microiontophoresis of kynurenate in area 17 neurons selectively suppressed the excitatory response to dorsal lateral geniculate nucleus and optic tract stimulation. In a second set of experiments, the effects of electrical stimulation of the dorsal lateral geniculate nucleus and the optic tract on the release of amino acids in the rat visual cortex in vivo were studied. Using the push–pull method, we perfused a discrete region of the visual cortex with artificial cerebrospinal fluid (CSF), and the amino acid content of the perfusates was analysed by high performance liquid chromatography (HPLC). Stimulation of either the dorsal lateral geniculate nucleus or the optic tract significantly increased glutamate release in area 17. The rest of the amino acids studied did not show significant changes. The results provide evidence for the participation of glutamate in the neurotransmission of the geniculo‐cortical pathway in the rat.
Neuroactive steroids induce GABAA receptor‐mediated depolarizing postsynaptic potentials in hippocampal CA1 pyramidal cells of the rat
Authors: Burg M. , Heinemann U. , Schmitz D. 
Published: December 2004

AbstractIntracellular recordings were performed in area CA1 pyramidal cells of rat hippocampal slices to determine the effects of certain steroids on inhibitory postsynaptic potentials/currents (IPSP/Cs) mediated by GABAA receptors. Following application of the steroids 5α‐pregnan‐3α,21‐diol‐20‐one (5α‐THDOC), alphaxalone and 5β‐pregnan‐3α‐ol‐20‐one (pregnanolone) hyperpolarizing PSPs developed into biphasic responses consisting of an early hyperpolarizing and a late depolarizing PSP sequence. Steroid‐induced depolarizing PSPs could be elicited in the presence of antagonists to non‐NMDA, NMDA, and GABAB receptors, indicating that these receptor types do not contribute significantly to the initiation of these responses. Depolarizing PSPs were completely blocked by both GABAA receptor antagonists bicuculline and t‐butylbicyclophosphorothionat (TBPS) providing evidence for their mediation by GABAA receptors. The reversal potential of steroid‐induced late inward PSCs, measured in single‐electrode voltage clamp, was −29.9 ± 5.3 mV, whereas the early outward current, which corresponded to the early hyperpolarizing component of PSPs, reversed at −68.2 ± 1.5 mV. Depolarizing PSPs and late inward PSCs were sensitive to reduction of extracellular [HCO3–] and block of carbonic anhydrase by application of acetazolamide. The results suggest that certain neuroactive steroids can induce GABAA receptor‐mediated depolarizing PSPs, which are dependent on HCO3–.
Survival motor neuron (SMN) protein in rat is expressed as different molecular forms and is developmentally regulated
Authors: Bella Vincenzo La , Cisterni Claire , Salaün Danièle , Pettmann Brigitte 
Published: December 2004

AbstractSpinal muscular atrophy (SMA) is an autosomal recessive disease characterized by a progressive degeneration of motoneurons in spinal cord and brainstem. The telomeric copy of a duplicated gene termed survival motor neuron (smn), which maps to chromosome 5q13, has been found to be deleted in most patients. The encoded gene product is a novel protein which recently has been shown to accumulate in specific nuclear organelles (gemini of coiled bodies, GEMS), and to play a part in the formation of the spliceosome complex. We have cloned and sequenced the rat smn cDNA. Antibodies generated against an N‐terminus peptide recognized a main protein of 32 kDa in immunoblots of rat embryonic tissue extracts. Minor bands of 35 kDa, 45 kDa and, in perinatal muscle, of 24 kDa were also specifically detected, indicating that SMN is expressed as different molecular forms. Subcellular fractionation indicated that the 32 kDa form is mainly soluble, while the 35 kDa and 45 kDa products segregate to the microsomal–mitochondrial fraction. SMN protein is highly regulated during development: expression is high in embryonic tissues (central nervous system, muscle, lung and liver), and then progressively decreases to very low levels in most tissues of the adult. The demonstration of different molecular forms of SMN along with its developmental regulation may help to understand the contribution of this protein in the appearance of SMA phenotype.
Expression of the GABAA receptor γ4‐subunit gene: anatomical distribution of the corresponding mRNA in the domestic chick forebrain and the effect of imprinting training
Authors: Harvey Robert J. , McCabe Brian J. , Solomonia Revaz O. , Horn Gabriel , Darlison Mark G. 
Published: December 2004

AbstractThe learning process of imprinting involves morphological, electrophysiological and biochemical changes in a region of the chick (Gallus gallus domesticus) forebrain known as the intermediate and medial part of the hyperstriatum ventrale (IMHV). The alterations include increases in the mean length of postsynaptic density profiles of axospinous synapses and the number of N‐methyl‐d‐aspartate (NMDA) receptor binding sites, and changes in spontaneous and evoked electrical activity. Recent immunocytochemical and behavioural studies have suggested that inhibitory GABAergic neurotransmission plays a role in learning. In this context, it has previously been reported that a novel avian γ‐aminobutyric acid (GABA) type A (GABAA) receptor gene, encoding the γ4 subunit, is highly expressed in the hyperstriatum ventrale. In this study, we have used in situ hybridization to map, in detail, the expression of the γ4‐subunit gene in the chick brain, and to assess the effect of imprinting training on the level of the corresponding transcript. Our results reveal that the γ4‐subunit mRNA has a restricted distribution, and demonstrate a highly significant, time‐dependent effect of training on its steady‐state level. At 10 h but not at 5 h after training there is a decrease (25–32%) in the amount of this transcript in parts of the medial hyperstriatum ventrale, including the IMHV. A decrease (28–39%) is also seen in certain visual and auditory pathway areas but no effect was observed in other forebrain regions such as the hyperstriatum intercalatus superior (HIS). These results suggest that imprinting training leads to a time‐dependent down‐regulation of GABAergic transmission, and raise the possibility that this down‐regulation plays a role in learning.
Rapid modulation of cortical proprioceptive activity induced by transient cutaneous deafferentation: neurophysiological evidence of short‐term plasticity across different somatosensory modalities in humans
Authors: Tinazzi Michele , Rosso Tiziana , Zanette Giampietro , Fiaschi Antonio , Aglioti Salvatore M. 
Published: December 2004

AbstractSingle cell recording in non‐human primates shows plastic changes of cortical somatic representations across different types of somatic inputs originating from the same peripheral territory. In humans, muscle afferents from first dorsal interosseus are supplied by the ulnar nerve while the cutaneous territory overlying this muscle is supplied by the radial nerve. This peculiar anatomical nervous distribution allowed us to devise an experimental model which provided a unique opportunity to assess, in humans with a non‐invasive technique, the functional relationships between cutaneous and muscle afferent inputs originating from the same peripheral territory. We recorded spinal, brainstem and cortical somatosensory potentials evoked by stimulation of muscle afferents of the right first dorsal interosseus before, during and after anaesthetic block of the sensitive branch of the ipsilateral radial nerve. Amplitude of parietal N20 and P27 and frontal N30 somatosensory evoked potential components showed an increase of amplitudes with more profound anaesthesia. Amplitudes returned to pre‐anaesthetic values several minutes after anaesthesia. By contrast, spinal N13 and brainstem P14 potentials did not change throughout the experiment. Results show, for the first time in humans, that a transient cutaneous deafferentation may induce rapid modulation of cortical activity evoked by stimulation of muscle afferents originating in the anaesthetic territory.
Glutamate activates NF‐κB through calpain in neurons
Authors: Schölzke Marion N. , Potrovita Ioana , Subramaniam Srinivasa , Prinz Simone , Schwaninger Markus 
Published: December 2004

AbstractGlutamate induces gene transcription in numerous physiological and pathological conditions. Among the glutamate‐responsive transcription factors, NF‐κB has been mainly implicated in neuronal survival and death. Recent data also suggest a role of NF‐κB in neural development and memory formation. In non‐neuronal cells, degradation of the inhibitor IκBα represents a key step in NF‐κB activation. However, little is known of how glutamate activates NF‐κB in neurons. To investigate the signalling cascade involved we used primary murine cerebellar granule cells. Glutamate induced a rapid reduction of IκBα levels and nuclear translocation of the NF‐κB subunit p65. The glutamate‐induced reduction of IκBα levels was blocked by the N‐methyl‐d‐aspartate inhibitor MK801. Specific inhibitors of the proteasome, caspase 3, and the phosphoinositide 3‐kinase had no effect on glutamate‐induced IκBα degradation. However, inhibition of the glutamate‐activated Ca2+‐dependent protease calpain by calpeptin completely blocked IκBα degradation and reduced the nuclear translocation of p65. Calpeptin also partially blocked glutamate‐induced cell death. Our data indicate that the Ca2+‐dependent protease calpain is involved in the NF‐κB activation in neurons in response to N‐methyl‐d‐aspartate receptor occupancy by glutamate. NF‐κB activation by calpain may mediate the long‐term effects of glutamate on neuron survival or memory formation.
Kv3 voltage‐gated potassium channels regulate neurotransmitter release from mouse motor nerve terminals
Authors: Brooke Ruth E. , Moores Thomas S. , Morris Neil P. , Parson Simon H. , Deuchars Jim 
Published: December 2004

AbstractVoltage‐gated potassium (Kv) channels are critical to regulation of neurotransmitter release throughout the nervous system but the roles and identity of the subtypes involved remain unclear. Here we show that Kv3 channels regulate transmitter release at the mouse neuromuscular junction (NMJ). Light‐ and electron‐microscopic immunohistochemistry revealed Kv3.3 and Kv3.4 subunits within all motor nerve terminals of muscles examined [transversus abdominus, lumbrical and flexor digitorum brevis (FDB)]. To determine the roles of these Kv3 subunits, intracellular recordings were made of end‐plate potentials (EPPs) in FDB muscle fibres evoked by electrical stimulation of tibial nerve. Tetraethylammonium (TEA) applied at low concentrations (0.05–0.5 mm), which blocks only a few known potassium channels including Kv3 channels, did not affect muscle fibre resting potential but significantly increased the amplitude of all EPPs tested. Significantly, this effect of TEA was still observed in the presence of the large‐conductance calcium‐activated potassium channel blockers iberiotoxin (25–150 nm) and Penitrem A (100 nm), suggesting a selective action on Kv3 subunits. Consistent with this, 15‐µm 4‐aminopyridine, which blocks Kv3 but not large‐conductance calcium‐activated potassium channels, enhanced evoked EPP amplitude. Unexpectedly, blood‐depressing substance‐I, a toxin selective for Kv3.4 subunits, had no effect at 0.05–1 µm. The combined presynaptic localization of Kv3 subunits and pharmacological enhancement of EPP amplitude indicate that Kv3 channels regulate neurotransmitter release from presynaptic terminals at the NMJ.
Shifting baselines and the decline of pelagic sharks in the Gulf of Mexico
Authors: Baum Julia K. , Myers Ransom A. 
Published: December 2004

AbstractHistorical abundances of many large marine vertebrates were tremendously greater than today. However, while pelagic sharks are known to have declined rapidly in the northwest Atlantic in recent years, there, as elsewhere, little is known about the former natural abundances of these species. Here, we compare initial (1950s) and recent (late‐1990s) standardized catch rates of pelagic sharks in the Gulf of Mexico, the area where methods of exploitation between these two periods were most comparable. We estimate that oceanic whitetip and silky sharks, formerly the most commonly caught shark species, have declined by over 99 and 90%, respectively. That the former prevalence of oceanic whitetip sharks in this ecosystem is unrecognized today is clear evidence of shifting baselines. Our analysis provides the missing baseline for pelagic sharks in the Gulf of Mexico that is needed for the rational management and restoration of these species.
Haldane rules: costs of outbreeding at production of daughters in sand lizards
Authors: Olsson Mats , Ujvari Beata , Madsen Thomas , Uller Tobias , Wapstra Erik 
Published: December 2004

AbstractHaldane's rule is one of the most widely applicable paradigms in evolutionary biology, stating that in species crossings, the heterogametic sex will suffer more severely in terms of sterility and inviability. We address this in a within‐species outbreeding situation by assessing the risk of producing inviable offspring depending on the sex ratio of the clutch produced in between‐population crossings in the laboratory. In crossings between male and female sand lizards (Lacerta agilis) from two different sampling regions, one in Sweden, one in central Europe, risk of gametic incompatibility is unaffected by outbreeding, but offspring from between‐population crossings show 300% higher malformation frequency and 10% lower hatching success. The risk of having inviable offspring increases with the production of daughters, i.e. the hemizygous sex in this species (ZW). Such sex‐specific genetic costs of offspring production need to be incorporated into life history ecology, e.g. sex allocation theory.
‘As Earth's testimonies tell’: wilderness conservation in a changing world
Authors: Gillson Lindsey , Willis Katherine J. 
Published: December 2004

AbstractToo often, wilderness conservation ignores a temporal perspective greater than the past 50 years, yet a long‐term perspective (centuries to millennia) reveals the dynamic nature of many ecosystems. Analysis of fossil pollen, charcoal and stable isotopes, combined with historical analyses and archaeology can reveal how ongoing interactions between climatic change, human activities and other disturbances have shaped today's landscapes over thousands of years. This interdisciplinary approach can inform wilderness conservation and also contribute to interpreting current trends and predicting how ecosystems might respond to future climate change. In this paper, we review literature that reveals how increasing collaboration among palaeoecologists, archaeologists, historians, anthropologists and ecologists is improving understanding of ecological complexity. Drawing on case studies from forested and non‐forested ecosystems in Europe, the Americas, Africa and Australia, we discuss how this integrated approach can inform wilderness conservation and ecosystem management.
Genome mosaicism is conserved but not unique in Pseudomonas aeruginosa isolates from the airways of young children with cystic fibrosis
Authors: Ernst Robert K. , D′Argenio David A. , Ichikawa Jeffrey K. , Bangera M. Gita , Selgrade Sara , Burns Jane L. , Hiatt Peter , McCoy Karen , Brittnacher Mitchell , Kas Arnold , Spencer David H. , Olson Maynard V. , Ramsey Bonnie W. , Lory Stephen , Miller Samuel I. 
Published: December 2004

Summary Pseudomonas aeruginosa strains from the chronic lung infections of cystic fibrosis (CF) patients are phenotypically and genotypically diverse. Using strain PAO1 whole genome DNA microarrays, we assessed the genomic variation in P. aeruginosa strains isolated from young children with CF (6 months to 8 years of age) as well as from the environment. Eighty‐nine to 97% of the PAO1 open reading frames were detected in 20 strains by microarray analysis, while subsets of 38 gene islands were absent or divergent. No specific pattern of genome mosaicism defined strains associated with CF. Many mosaic regions were distinguished by their low G + C content; their inclusion of phage related or pyocin genes; or by their linkage to a vgr gene or a tRNA gene. Microarray and phenotypic analysis of sequential isolates from individual patients revealed two deletions of greater than 100 kbp formed during evolution in the lung. The gene loss in these sequential isolates raises the possibility that acquisition of pyomelanin production and loss of pyoverdin uptake each may be of adaptive significance. Further characterization of P. aeruginosa diversity within the airways of individual CF patients may reveal common adaptations, perhaps mediated by gene loss, that suggest new opportunities for therapy.
Early steps in microbial colonization processes at deep‐sea hydrothermal vents
Authors: Alain Karine , Zbinden Magali , Le Bris Nadine , Lesongeur Françoise , Quérellou Joël , Gaill Françoise , Cambon‐Bonavita Marie‐Anne 
Published: December 2004

SummaryA pluri‐disciplinary in situ colonization experiment was performed to study early stages of colonization in deep‐sea vent Alvinella spp. worm habitats. Four colonization devices were deployed onto Alvinella spp. colonies of different chimneys of the East‐Pacific Rise (EPR 13°N), for two different periods: a short (less than a week) and a longer one (3 weeks). Video imagery and monitoring of the thermal and physico‐chemical conditions were performed during the colonization experiments. Numerous microorganisms bearing specialized adhesion‐appendages and/or high amounts of polymeric extracellular matrix were observed on devices, which may efficiently contribute to the colonization of new surfaces. The microbial cohorts preceding and accompanying Alvinella spp. settlement were identified. In all cases, Archaea could not be detected and the microbial mats were essentially composed of e‐Proteobacteria. Within this group, one phylotype (AlviH2) was found to dominate the libraries of three colonization devices. Dominance of e‐Proteobacteria in the libraries may reflect the wide physiological variety encountered within this group or an adaptability of these microorganisms towards their changing environment. Bacteria affiliated to the Cytophaga‐Flavobacterium‐Bacteroides group or to the e‐Proteobacteria, that grow either chemo‐organoheterotrophically by fermentation or chemolithoautotrophically with H2 as an electron donor and S°/S2O32– or NO3– as a terminal electron acceptor, were isolated from one of the microbial mat formed in 20 days.
Efficacy and safety comparative evaluation of orlistat and sibutramine treatment in hypertensive obese patients
Authors: Derosa G. , Cicero A. F. G. , Murdolo G. , Piccinni M. N. , Fogari E. , Bertone G. , Ciccarelli L. , Fogari R. 
Published: December 2004

Aim:  The aim of our study was to comparatively evaluate the efficacy and safety of orlistat and sibutramine treatment in obese hypertensive patients, with a specific attention to cardiovascular effects and to side effects because of this treatment.Methods:  Patients were enrolled, evaluated and followed at three Italian Centres of Internal Medicine. We evaluated 115 obese and hypertensive patients. (55 males and 60 females; 26 males and 29 females, aged 50 ± 4 with orlistat; 28 males and 30 females, aged 51 ± 5 with sibutramine). All patients took antihypertensive therapy for at least 6 months before the study. We administered orlistat or sibutramine in a randomized, controlled, double‐blind clinical study. We evaluated anthropometric variables, blood pressure and heart rate (HR) during 12 months of this treatment.Results:  A total of 113 completed the 4 weeks with controlled energy diet and were randomized to double‐blind treatment with orlistat (n = 55) or sibutramine (n = 58). Significant body mass index (BMI) improvement was present after 6 (p < 0.05), 9 (p < 0.02), and 12 (p < 0.01) months in both groups, and body weight (BW) improvement was obtained after 9 (p < 0.05) and 12 (p < 0.02) months in both groups. Significant waist circumference (WC), hip circumference (HC) and waist/hip ratio (W/H ratio) improvement was observed after 12 months (p < 0.05, respectively) in both groups. Significant systolic blood pressure (SBP) and diastolic blood pressure (DBP) improvement (p < 0.05) was present in orlistat group after 12 months. Lipid profile [total cholesterol (TC), low‐density lipoprotein‐cholesterol (LDL‐C) and triglycerides] reduction (p < 0.05, respectively) was observed in orlistat group and triglyceride reduction (p < 0.05) in sibutramine group after 12 months. No significant change was observed in sibutramine group during the study. No significant HR variation was obtained during the study in both groups. Of the 109 patients who completed the study, 48.1% of patients in the orlistat group and 17.5% of patients in the sibutramine group had side effects (p < 0.05 vs. orlistat group). Side‐effect profiles were different in the two treatment groups. All orlistat side effects were gastrointestinal events. Sibutramine caused an increase in blood pressure (both SBP and DBP) in two patients, but it has been controlled by antihypertensive treatment. The vitamin changes were small and all mean vitamin and β‐carotene values stayed within reference ranges. No patients required vitamin supplementation.Conclusions:  Both orlistat and sibutramine are effective on anthropometric variables during the 12‐month treatment; in our sample, orlistat has been associated to a mild reduction in blood pressure, while sibutramine assumption has not be associated to any cardiovascular effect and was generically better tolerated than orlistat.