bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cellular dynamics underlying regeneration of damaged axons differs from initial axon development
Authors: Blizzard C. A. , Haas M. A. , Vickers J. C. , Dickson T. C. 
Published: September 2007

AbstractWhile long‐distance regeneration may be limited in mammalian species, it is becoming apparent that damaged mature neurons retain some capacity for attempted regeneration and that the adult CNS is not entirely inhibitory to axon growth. Our investigations show that there are critical intrinsic features of postinjury axonal regeneration that differ from initial axon development, and that these distinct differences may account for the limited and inappropriate regenerative response that currently characterizes the mature CNS. We compared the neurochemical and dynamic characteristics of developing axons to relatively mature regenerating axons, utilizing an in vitro model of axonal transection to long‐term cultured rat cortical neurons. Immunolabelling studies revealed that regenerating and developing axons have a similar localization of cytoskeletal proteins, but the tips of regenerating axons, although morphologically similar, were smaller with reduced fillopodial extension, relative to developmental growth cones. Live imaging demonstrated that regenerating axons exhibited significantly less outgrowth than developmental neurites. Furthermore, growth cones of regenerating axons had a significant reduction in pausing, considered vital for interstitial branching and pathfinding, than did developmental growth cones. In addition, unlike developing axons, the regenerating axons were unresponsive to the growth factors BDNF and GDNF. Thus, although similar in their cytoskeletal composition, the growth cones of regenerative sprouts differed from their developmental counterparts in their size, their dynamic behaviour and their ability to respond to critical growth factors. These intrinsic differences may account for the inability of post‐traumatic locally sprouting axons to make accurate pathway decisions and successfully respond to trauma.
Domain‐specific retrieval of source information in the medial temporal lobe
Authors: Peters Jan , Suchan Boris , Köster Odo , Daum Irene 
Published: September 2007

AbstractMemory for context information (source memory) has been reported to rely on structures in the medial temporal lobe (MTL). Perirhinal cortex (anterior MTL) and parahippocampal cortex (posterior MTL) have distinct connectivity patterns with sensory neocortex, suggesting a possible modality‐dependent organization of memory processes. The present study investigated the neural substrates of two different types of source information of newly encoded material using functional magnetic resonance imaging: auditory (speaker voice) and visual (texture and colour). Source judgements during retrieval were reliably above chance level for both modalities and performance did not differ between the auditory and visual condition. During encoding, activity predictive of subsequent source recollection was observed in the anterior hippocampus/parahippocampal gyrus, irrespective of source modality. During retrieval, on the other hand, a regional dissociation emerged: bilateral parahippocampal cortex discriminated between correct and incorrect auditory but not visual source judgements, whereas left perirhinal/entorhinal cortex showed the reverse pattern. These findings are consistent with recent lesion evidence of disrupted auditory but intact visual source memory following damage to the parahippocampal cortex. Results are discussed with respect to anatomical models of corticoparahippocampal connectivity and the functional organization of the MTL.
The involvement of spinal bovine adrenal medulla 22‐like peptide, the proenkephalin derivative, in modulation of nociceptive processing
Authors: Cai Meifang , Chen Tingjun , Quirion Rémi , Hong Yanguo 
Published: September 2007

AbstractBovine adrenal medulla 22 (BAM22), one of the cleavage products of proenkephalin A, possesses high affinity for opioid receptors and sensory neuron‐specific receptor (SNSR). The present study was designed to examine the expression of BAM22 in the spinal cord and dorsal root ganglion (DRG) of naive rats as well as in a model of inflammation. BAM22‐like immunoreactivity (BAM22‐IR) was expressed in fibers in the spinal cord, with high density seen in lamina I in naïve rats. The expression of BAM22‐IR in the superficial laminae was greatly reduced following dorsal rhizotomy. BAM22‐IR was also located in 19% of DRG cells, mainly in the small‐ and medium‐sized subpopulations. Following injection of complete Freund's adjuvant (CFA) in the hindpaw, the expression of BAM22‐IR in the superficial laminae of the spinal cord and small‐sized DRG neurons on the ipsilateral side was markedly increased. Double labeling showed that the Fos‐positive nucleus was surrounded by BAM22‐IR cytoplasm in the spinal dorsal horn neurons or closely associated with BAM22‐IR fibers in the superficial laminae. Furthermore, CFA‐induced mechanical allodynia in the inflamed paw was potentiated by intrathecal administration of anti‐BAM22 antibody. Together, these results demonstrate for the first time that BAM22‐like peptide is mainly located in the superficial laminae of the spinal cord and mostly originates from nociceptive DRG neurons. BAM22 could thus act as a ligand for presynaptic opioid receptors and SNSR. Our study also provides evidence suggesting that BAM22 plays a role in the modulation of nociceptive processing at the spinal level under normal and inflammatory conditions.
Acetylcholine‐mediated axon‐glia signaling in the developing insect olfactory system
Authors: Heil Jan E. , Oland Lynne A. , Lohr Christian 
Published: September 2007

AbstractIn the olfactory system of the sphinx moth Manduca sexta, migration of neuropil glial cells is triggered by olfactory receptor axons and depends on intraglial Ca2+ signaling. It is not known, however, how receptor axons and glial cells communicate and whether Ca2+ signaling is a consequence of this communication. We studied Ca2+ increases in glial cells in vivo and in situ, evoked by electrical stimulation of olfactory receptor axons in pupae and by odor stimulation of receptor neurons in adult moths. Axonal activity leads to Ca2+ increases in neuropil glial cells that are blocked by nicotinic acetylcholine receptor antagonists and can be mimicked by acetylcholine and carbachol application. In addition, Ca2+ transients were abolished by removal of external Ca2+ and blockage of voltage‐gated Ca2+ channels. During development, acetylcholine‐mediated Ca2+ signaling could first be elicited at stage 6, the time when neuropil glial cells start to migrate. Glial migration was reduced after injection of nicotinic antagonists into pupae. The results show that Ca2+ signaling can be induced by acetylcholine release from olfactory receptor axons, which activates nicotinic acetylcholine receptors and leads to voltage‐gated Ca2+ influx. The results further suggest that cholinergic signaling in the olfactory system is required for glial cell migration in Manduca.
A brief, but repeated, swimming protocol is sufficient to overcome amyloid β‐protein inhibition of hippocampal long‐term potentiation
Authors: Li Shaomin , Feig Larry A. , Hartley Dean M. 
Published: September 2007

AbstractAlzheimer's disease starts as an almost imperceptible malady, first observed clinically as a mild memory problem. Accumulating genetic and biochemical data have suggested that amyloid β‐protein (Aβ) plays an important role in this memory loss, and Aβ has been shown to suppress long‐term potentiation (LTP), a cellular model for memory and learning. Here we show that a very brief (3 min) swimming, twice daily for 2 weeks, rescues LTP inhibition in the CA1 region of hippocampal slices caused by Aβ42 or Aβ40 carrying the Arctic mutation using a theta burst stimulation (TBS) protocol. Whereas the input–output curve was not affected, the paired‐pulse ratio was reduced in mice receiving our repeated swimming protocol, suggesting a possible involvement of presynaptic facilitation. Similar to swimming, Aβ's inhibition of LTP could be rescued with the adenylyl cyclase, forskolin. Interestingly, this swimming protocol produced conditions in which a weak‐TBS could invoke LTP not observed in naïve mice, which again was mimicked by forskolin. In contrast, the protein kinase A (PKA) inhibitor, H89, blocked both the forskolin and swimming potentiation of LTP; these data implicate cAMP/PKA signaling in the protective effect of swimming and mediating Aβ′ detrimental effects. Our data add a new simple behavior paradigm that shows the importance of an environmental factor in reversing the pathophysiological effects of Aβ, and suggest new therapeutic avenues.
Differential modulation by monoamine membrane receptor agonists of reticulospinal input to lamina VIII feline spinal commissural interneurons
Authors: Hammar Ingela , Stecina Katinka , Jankowska Elzbieta 
Published: September 2007

AbstractNoradrenaline and serotonin have previously been demonstrated to facilitate the transmission between descending reticulospinal tracts fibres and commissural interneurons coordinating left–right hindlimb muscle activity. The aim of the present study was to investigate the contribution of subclasses of monoaminergic membrane receptors to this facilitation. The neurons were located in Rexed lamina VIII in midlumbar segments and identified by their projections to the contralateral gastrocnemius–soleus motor nuclei and by lack of projections rostral to the lumbosacral enlargement. The effects of ionophoretically applied membrane receptor agonists [phenylephrine (noradrenergic α1), clonidine (noradrenergic α2), 8‐OH‐DPAT (5‐HT1A, 5‐HT7), 2‐me‐5‐HT (5‐HT3), 5‐me‐5‐HT (5‐HT2) and α‐me‐5‐HT (5‐HT2)] were examined on extracellularly recorded spikes evoked monosynaptically by electric stimulation of descending reticulospinal fibres in the medial longitudinal fascicle. Application of α1 and 5‐HT2 agonists resulted in a facilitation of responses in all investigated neurons while application of α2, 5‐HT1A/7 and 5‐HT3 agonists resulted in a depression. These opposite modulatory effects of different agonists suggest that the facilitatory actions of noradrenaline and serotonin on responses of commissural interneurons reported previously following ionophoretic application are the net outcome of the activation of different subclasses of monoaminergic membrane receptors. As these receptors may be distributed predominantly, or even selectively, at either pre‐ or postsynaptic sites their differential modulatory actions could be compatible with a presynaptically induced depression and a postsynaptically evoked enhancement of synaptic transmission between reticulospinal neurons and commissural interneurons.
The carina is not a landmark for central venous catheter placement in neonates
Authors: INAGAWA GAKU , KA KOUI , TANAKA YUKICHI , KATO KEISUKE , TANAKA MIO , MIWA TAKAAKI , MORIMURA NAOTO , KOYAMA YUKIHIDE , HIROKI KOICHI 
Published: September 2007

SummaryBackground:  Cardiac tamponade is rare but one of the most serious complications in relation to central venous catheters (CVC). The tip of the CVC should be placed outside the pericardium to avoid tamponade. In adults, the carina is always located above the pericardium; therefore, the carina is a reliable landmark for CVC placement. We examined whether the carina could also be an adequate landmark for CVC placement in neonates.Methods:  The study was conducted using nine fresh neonatal cadavers. The longitudinal distance between the carina and the pericardium as it transverses the superior vena cava (the pericardial reflection: PR) was measured.Results:  The median postconceptional age (gestational age in weeks + weeks after delivery) at autopsy was 35 (range: 23–42) weeks. The PR was located at a distance of 4 mm above to 5 mm below the carina. Unlike in adults, the position of the PR varies in relation to the carina in neonates. In seven of the nine subjects, the location of the PR was above the carina.Conclusions:  In neonates, the carina is not always located above the pericardium, as it is in adults; therefore, the carina is not an appropriate landmark for CVC placement.
Standard preoxygenation vs two techniques in children
Authors: CHIRON BRUNO , MAS CHRISTOPHE , FERRANDIÈRE MARTINE , BONNARD CHRISTIAN , FUSCIARDI JACQUES , MERCIER COLETTE , LAFFON MARC 
Published: September 2007

SummaryBackground:  Preoxygenation is recommended in pediatric anesthesia but it has been poorly assessed. Fractional expired oxygen concentration (FETO2) is a preoxygenation monitor. The aim of this prospective study in children was to compare three techniques of preoxygenation by the measurement of FETO2.Methods:  Twenty children (6–15 years) were included. FETO2 was measured with the child in a supine position, holding the facemask. The FETO2 value was measured after 3 min of calm breathing of room air (baseline) and during the three preoxygenation techniques performed in random order: 3 min of tidal volume breathing using an O2 flow of 9 l·min−1 (TV × 3 min) – four deep breaths within 30 s using an O2 flow of 15 l·min−1 (4 DB) – eight deep breaths within 1 min using an O2 flow of 15 l·min−1 (8 DB). Between each technique, at least 5 min breathing room air was allowed to return to baseline FETO2. Fisher’s exact test was used and P < 0.05 was considered significant.Results:  Twenty children were studied (age: 11.5 ± 3 years, weight: 42 ± 21 kg). The FETO2 ≥ 90% was found to be 79% in 74 ± 40 s with TV × 3 min, 11% with 4 DB, and 68% with 8 DB.Conclusions:  In children, Vt × 3 min is the most efficient preoxygenation technique to reach FETO2 ≥ 90%.
Anesthetic implications of undiagnosed late onset central hypoventilation syndrome in a child: from elective tonsillectomy to tracheostomy
Authors: MAHMOUD MOHAMED , BRYAN YVON , GUNTER JOEL , KREEGER RENEE N. , SADHASIVAM SENTHILKUMAR 
Published: September 2007

SummaryLate onset central hypoventilation syndrome is a neurological disorder that can present with postoperative respiratory complications and delayed emergence in children after anesthesia. We present a child who had unanticipated respiratory complications following an elective tonsillectomy who eventually required a tracheostomy and long‐term ventilatory support.
Airway management and anesthesia in neonates, infants and children during endolaryngotracheal surgery
Authors: MAUSSER GERLINDE , FRIEDRICH GERHARD , SCHWARZ GERHARD 
Published: September 2007

SummaryBackground:  Endolaryngotracheal surgery in neonates, infants and children poses a big challenge for both anesthesiologist and surgeon. The narrowness of the airways and the great variability of the pathological lesions necessitate close collaboration between the surgical and the anesthesia team to provide optimal operating conditions and ensure adequate ventilation and oxygenation.Methods:  Sixty‐two anesthetic records of endolaryngotracheal surgical procedures in neonates, infants and children with ASA physical status 1–3 were analyzed retrospectively. Anesthesia was administered as total intravenous anesthesia; propofol supplemented with remifentanil. Ventilation was performed as supraglottic, superimposed high‐frequency jet ventilation via jet laryngoscope with integrated jet nozzles.Results:  Age was 58.93 (SD 35.40) months, range 3 weeks to 14 years; body weight 17.83 (SD 8.79) kg, range 2.4–50 kg. The capillary pCO2 5 min after the start of the surgical procedure (n = 62) was 40.01 (SD 7.71) mmHg and after 20 min (n = 24) 41.77 (SD 7.12) mmHg. No hypoxemia (oxygen saturation <90%) developed. All patients were hemodynamically stable during jet ventilation. Barotrauma or gas insufflation in the stomach did not occur. No perioperative tracheostomy was necessary. Laryngospasm occurred in one child during emergence from anesthesia. Four infants received postoperative conventional respirator therapy in the ICU overnight.Conclusions:  Supraglottic superimposed high‐/low‐frequency jet ventilation via jet laryngoscopes with integrated jet nozzles is a minimally invasive ventilation technique for neonates, infants and children in endolaryngotracheal surgery, which allows an unimpaired operating field for the surgeon especially in LASER surgery.
Amyloid adhesins are abundant in natural biofilms
Authors: Larsen Poul , Nielsen Jeppe Lund , Dueholm Morten Simonsen , Wetzel Ronald , Otzen Daniel , Nielsen Per Halkjær 
Published: September 2007

SummarySurface‐associated amyloid fibrils have been described by bacteria in the family Enterbacteriaceae, but it is unknown to what extent amyloid adhesins are present in natural biofilms. In this study, amyloid adhesins were specifically stained with Thioflavin T and two conformationally specific antibodies targeting amyloid fibrils. These three independent detection methods were each combined with fluorescence in situ hybridization using fluorescently labelled oligonucleotide probes in order to link phenotype with identity. Escherichia coli mutants with and without amyloid adhesins (curli) served as controls. In biofilms from four different natural habitats, bacteria producing extracellular amyloid adhesins were identified within several phyla: Proteobacteria (Alpha‐, Beta‐, Gamma‐ and Deltaproteobacteria), Bacteriodetes, Chloroflexi and Actinobacteria, and most likely also in other phyla. Quantification of the microorganisms producing amyloid adhesins showed that they constituted at least 5–40% of all prokaryotes present in the biofilms, depending on the habitat. Particularly in drinking water biofilms, a high number of amyloid‐positive bacteria were identified. Production of amyloids was confirmed by environmental isolates belonging to the Gammaproteobacteria, Bacteriodetes, Firmicutes and Actinobacteria. The new approach is a very useful tool for further culture‐independent studies in mixed microbial communities, where the abundance and diversity of bacteria expressing amyloid adhesins seems much greater than hitherto anticipated.
Microbial community diversity in the phycosphere of natural populations of the toxic alga, Alexandrium fundyense
Authors: Hasegawa Yuko , Martin Jennifer L. , Giewat Michael W. , Rooney‐Varga Juliette N. 
Published: September 2007

SummaryThe dinoflagellate Alexandrium fundyense is the major causative organism of paralytic shellfish poisoning in the Gulf of Maine. While laboratory studies have shown that A. fundyense population dynamics can be affected dramatically by co‐occurring bacteria, little is known about these interactions in nature. Because A. fundyense is typically a minor Gulf of Maine phytoplankton community member, analyses of the bulk community cannot be used to address bacterium–A. fundyense associations. Therefore, an immunomagnetic bead method was used to selectively capture A. fundyense cells, and the bacteria attached to them, from complex natural samples. Bulk particle‐associated and free‐living bacterial communities were collected simultaneously. DNA was extracted from all sample types and subjected to 16S rRNA gene fragment amplification, denaturing gradient gel electrophoresis (DGGE) and sequence analysis. Ordination analysis of DGGE profiles confirmed that A. fundyense‐associated bacteria community profiles were distinct from bulk bacterial community profiles, indicating selection of specific phylotypes in the A. fundyense phycosphere. Phylogenetic analyses confirmed that Alexandrium‐associates were distinct from bulk particle‐associated bacteria and that they included a greater prevalence and broader diversity of Gammaproteobacteria than previously thought to be associated with toxic algae. Phylogenetic groups known to be associated with dinoflagellates were also found, including members of the families Alteromonadaceae, Pseudoalteromonadaceae, Rhodobacteraceae and Flavobacteraceae.
Identification of novel perchloroethene‐respiring microorganisms in anoxic river sediment by RNA‐based stable isotope probing
Authors: Kittelmann Sandra , Friedrich Michael W. 
Published: September 2007

SummaryThe halogenated compound tetrachloroethene (perchloroethene, PCE) is a persistent contaminant of aquifers, soils and sediments. Although a number of microorganisms are known to reductively dechlorinate PCE by dehalorespiration, their diversity and community structure especially in pristine environments remain elusive. In this study, we report on the detection of a novel group of dehalorespiring bacteria that reductively dechlorinate PCE to cis‐dichloroethene by RNA‐based stable isotope probing. Pristine river sediment was incubated at 15°C with PCE at low aqueous concentration. Upon formation of dechlorination products, the microbial community was probed with 13C‐labelled acetate as electron donor and carbon source. Terminal restriction fragment length polymorphism (T‐RFLP) analysis of density‐separated 16S rRNA revealed a predominantly 13C‐labelled bacterial population only in the microcosm with PCE in high‐density gradient fractions, whereas in the control without PCE Bacteria‐specific rRNA was restricted to light gradient fractions. By cloning and sequence analysis of 16S rRNA, the predominant population was identified as a novel group of bacteria within the phylum Chloroflexi. These microorganisms, designated Lahn Cluster (LC), were only distantly related to cultivated dehalorespiring Dehalococcoides spp. (92–94% sequence identity). Minor clone groups detected 13C‐labelled and thus, potentially involved in PCE dehalorespiration, were related to β‐proteobacterial Dechloromonas spp., and δ‐Proteobacteria (Geobacteraceae, Desulfobacteraceae, Desulfobulbaceae). In contrast, clones from an ethene‐producing microcosm incubated at 20°C grouped with known Dehalococcoides spp. Our results show that stable isotope probing allows targeting dehalorespiring bacteria as functional guild, and to identify novel PCE‐respiring populations previously not recognized.
Modifying lysine biosynthesis and catabolism in corn with a single bifunctional expression/silencing transgene cassette
Authors: Frizzi Alessandra , Huang Shihshieh , Gilbertson Larry A. , Armstrong Toni A. , Luethy Michael H. , Malvar Thomas M. 
Published: September 2007

SummaryAlthough it is one of the major crops in the world, corn has poor nutritional quality for human and animal consumption due to its low lysine content. Here, we report a method of simultaneous expression of a deregulated lysine biosynthetic enzyme, CordapA, and reduction of a bifunctional lysine degradation enzyme, lysine‐ketoglutarate reductase/saccharophine dehydrogenase (LKR/SDH), in transgenic corn plants by a single transgene cassette. This is accomplished by inserting an inverted‐repeat sequence targeting the maize LKR/SDH gene into an intron of a transgene cassette that expresses CordapA. This combination of LKR/SDH silencing and CordapA expression led to the accumulation of free lysine to over 4000 p.p.m. in transgenic corn grain, compared to less than 100 p.p.m. in wild‐type controls. This intron‐embedded silencing cassette design reduces the number of transgene cassettes needed in transgenic approaches for manipulating metabolic pathways that sometimes require expression of one gene and silencing of another.