bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunocytochemical characterization of rat brainstem neurons with vagal afferent input from the stomach challenged by acid or ammonia
Authors: Danzer Marion , Samberger Claudia , Schicho Rudolf , Lippe Irmgard Th. , Holzer Peter 
Published: December 2004

AbstractExposure of the gastric mucosa to backdiffusing acid is signalled to the brainstem via vagal afferents. This study examined whether exposure of the Sprague–Dawley rat stomach to hydrochloric acid (HCl) or ammonium hydroxide (NH4OH), a noxious chemical produced by Helicobacter pylori, activates different vagal afferent pathways as reflected by different circuitries in the medullary brainstem. Two hours after intragastric treatment with HCl or NH4OH the activation of neurons in the nucleus tractus solitarii at the rostrocaudal extension of the area postrema (NTSAP) was visualized by c‐Fos immunohistochemistry and their chemical coding characterized by double‐labelling immunohistochemistry. Exposure of the rat gastric mucosa to HCl (0.15–0.5 m) or NH4OH (0.1–0.3 m) led to a concentration‐dependent expression of c‐Fos in the NTSAP. The number and distribution of NTSAP neurons activated by 0.35 m HCl and 0.3 m NH4OH were similar; the highest number of activated neurons occurring in the medial part of the NTSAP. Some 60% of the NTSAP neurons activated by intragastric HCl and NH4OH stained for the high affinity glutamate transporter EAAC1, while some 30% contained calbindin or neuropeptide Y. Glutamate receptors of the N‐methyl‐d‐aspartate type were found on approximately 50% of the c‐Fos‐positive cells in the NTSAP, whereas tachykinin NK1, NK2 and NK3 receptors were present on 5–10% of the activated neurons. The similar number and distribution of c‐Fos‐expressing neurons within the NTSAP and their identical chemical coding indicate that exposure of the rat stomach to backdiffusing concentrations of HCl and NH4OH activates the same vagal afferent – NTSAP pathway.
Gene expression profiling reveals multiple novel intrinsic and extrinsic factors associated with axonal regeneration failure
Authors: Küry Patrick , Abankwa Daniel , Kruse Fabian , Greiner‐Petter Regine , Müller Hans Werner 
Published: December 2004

AbstractIn contrast to the regeneration‐competent peripheral nervous system (PNS), lesions of nerve tracts within the central nervous system (CNS) lead to chronically impaired neuronal connections. We have analysed changes in gene expression patterns occurring as a consequence of postcommissural fornix transection at a time when spontaneous axonal growth has ceased at the lesion site. This was done in order to describe both extrinsic and intrinsic determinants of regeneration failure. Using a genomic approach we have identified a number of so far undetected factors such as bamacan and semaphorin 6B, which relate to chronic axonal growth arrest and therefore are promising candidates for lesion‐induced axonal growth inhibitors. In addition, we observed that within the subiculum, where the fornix axons originate, neuronal Oct‐6 was induced and NG2 was down‐regulated, indicating that axotomized neurons as well as glial cells react at the level of gene expression to remote axotomy.
Nitric oxide‐induced cell death in developing oligodendrocytes is associated with mitochondrial dysfunction and apoptosis‐inducing factor translocation
Authors: Baud Olivier , Li Jianrong , Zhang Yumin , Neve Rachael L. , Volpe Joseph J. , Rosenberg Paul A. 
Published: December 2004

AbstractReactive nitrogen species are thought to be involved in both hypoxic‐ischemic and cytokine‐induced brain injury, including periventricular leukomalacia (PVL), the major pathological substrate of cerebral palsy in premature infants. PVL appears to be the result of perinatal inflammatory events and hypoxic‐ischemic injury to the cerebral white matter. The chronic disturbance of myelination resulting from PVL suggests that developing oligodendrocytes (OLs) are involved in its pathogenesis. We hypothesized that nitric oxide (NO) could participate in the pathogenesis of PVL through a toxic effect on developing OLs. Using primary cultures of highly enriched OLs we found that NO is toxic to developing OLs (O4+, O1–, MBP–), with an EC50value of 236 ± 125 µmof DETANOnoate. Peroxynitrite formation does not appear to be involved in NO toxicity in developing OLs, as determined by the failure of peroxynitrite scavengers as well as superoxide dismutase overexpression to prevent NO‐induced toxicity. Similarly, several pathways involving PARP, excitotoxicity, guanylyl cyclase and caspase activation were not related to NO toxicity to developing OLs. NO toxicity to OLs resulted in ATP depletion and loss of mitochondrial membrane potential (ΔΨ) in developing OLs. Apoptosis‐inducing factor (AIF) has been shown to be involved in caspase‐independent cell death, and we found that AIF translocated from mitochondria into the nucleus upon NO exposure. In conclusion, we suggest that the vulnerability of developing OLs to NO involves mitochondrial dysfunction and translocation of AIF from mitochondria to nuclei.
Synaptic release of dopamine in the subthalamic nucleus
Authors: Cragg Stephanie J. , Baufreton Jérôme , Xue Yi , Bolam J. Paul , Bevan Mark D. 
Published: December 2004

AbstractThe direct modulation of subthalamic nucleus (STN) neurons by dopamine (DA) neurons of the substantia nigra (SN) is controversial owing to the thick caliber and low density of DA axons in the STN. The abnormal activity of the STN in Parkinson's disease (PD), which is central to the appearance of symptoms, is therefore thought to result from the loss of DA in the striatum. We carried out three experiments in rats to explore the function of DA in the STN: (i) light and electron microscopic analysis of tyrosine hydroxylase (TH)‐, dopamine β‐hydroxylase (DβH)‐ and DA‐immunoreactive structures to determine whether DA axons form synapses; (ii) fast‐scan cyclic voltammetry (FCV) to determine whether DA axons release DA; and (iii) patch clamp recording to determine whether DA, at a concentration similar to that detected by FCV, can modulate activity and synaptic transmission/integration. TH‐ and DA‐immunoreactive axons mostly formed symmetric synapses. Because DβH‐immunoreactive axons were rare and formed asymmetric synapses, they comprised the minority of TH‐immunoreactive synapses. Voltammetry demonstrated that DA release was sufficient for the activation of receptors and abolished by blockade of voltage‐dependent Na+channels or removal of extracellular Ca2+. The lifetime and concentration of extracellular DA was increased by blockade of the DA transporter. Dopamine application depolarized STN neurons, increased their frequency of activity and reduced the impact of γ‐aminobutyric acid (GABA)‐ergic inputs. These findings suggest that SN DA neurons directly modulate the activity of STN neurons and their loss may contribute to the abnormal activity of STN neurons in PD.
Genetically based trait in a dominant tree affects ecosystem processes
Authors: Schweitzer Jennifer A. , Bailey Joseph K. , Rehill Brian J. , Martinsen Gregory D. , Hart Stephen C. , Lindroth Richard L. , Keim Paul , Whitham Thomas G. 
Published: December 2004

AbstractFundamental links between genes and ecosystem processes have remained elusive, although they have the potential to place ecosystem sciences within a genetic and evolutionary framework. Utilizing common gardens with cottonwood trees of known genotype, we found that the concentration of condensed tannins is genetically based and is the best predictor of ecosystem‐level processes. Condensed tannin inputs from foliage explained 55–65% of the variation in soil net nitrogen (N) mineralization under both field and laboratory conditions. Alternative associations with litter lignin, soil moisture or soil temperature were relatively poor predictors of litter decomposition and net N mineralization. In contrast to the paradigm that the effects of genes are too diffuse to be important at the ecosystem‐level, here we show that plant genes had strong, immediate effects on ecosystem function via a tight coupling of plant polyphenols to rates of nitrogen cycling.
Beyond biodiversity: individualistic controls of invasion in a self‐assembled community
Authors: Meiners Scott J. , Cadenasso Mary L. , Pickett Steward T. A. 
Published: December 2004

AbstractRecent experimental and simulation results, and competition‐based ecological theory, predict a simple relationship between species richness and the invasibility of communities at small spatial scales – likelihood of invasion decreases with increasing richness. Here we show data from 42 continuous years of sampling old field succession that reveal quite different dynamics of plant invasion. Contrary to experimental studies, when richness was important in explaining invasion probability, it was typically positively associated with species invasion. Invasion of several species had a unimodal response to resident species richness, which appeared to be a mixture of compositional influences and a richness effect. Interestingly, invasions by native and exotic species did not fundamentally differ. Control of species invasion in this system is individualistic, caused by a variety of community‐level mechanisms rather than a single prevailing richness effect.
Variation in migration propensity among individuals maintained by landscape structure
Authors: Hanski Ilkka , Erälahti Claudia , Kankare Maaria , Ovaskainen Otso , Sirén Heli 
Published: December 2004

AbstractMetapopulation dynamics lead to predictable patterns of habitat occupancy, population density and trophic structure in relation to landscape features such as habitat patch size and isolation. Comparable patterns may occur in behavioural, physiological and life‐history traits but remain little studied. In the Glanville fritillary butterfly, females in newly established populations were more mobile than females in old populations. Among females from new populations, mobility decreased with increasing connectivity (decreasing isolation), but in females from old populations mobility increased with connectivity. The [ATP]/[ADP] ratio of flight muscles following controlled activity showed the same pattern as mobility in relation to population age and connectivity, suggesting that physiological differences in flight metabolic performance contribute to the observed variation in mobility. We demonstrate with an evolutionary metapopulation model parameterised for the Glanville fritillary that increasing spatial variation in landscape structure increases variance in mobility among individuals in a metapopulation, supporting the general notion that complex landscape structure maintains life‐history variation.
Chaotropic solutes cause water stress in Pseudomonas putida
Authors: Hallsworth John E. , Heim Sabina , Timmis Kenneth N. 
Published: December 2004

SummaryLow water availability is the most ubiquitous cause of stress for terrestrial plants, animals and microorganisms, and has a major impact on ecosystem function and agricultural productivity. Studies of water stress have largely focused on conditions that affect cell turgor, i.e. induce osmotic stress. We show that chaotropic solutes that do not affect turgor reduce water activity, perturb macromolecule–water interactions and thereby destabilize cellular macromolecules, inhibit growth, and are powerful mediators of water stress in a typical soil bacterium, Pseudomonas putida. Chaotropic solute‐induced water stress resulted mostly in the upregulation of proteins involved in stabilization of biological macromolecules and membrane structure. Many environmental pollutants and agricultural products are chaotropic chemicals and thus constitute a previously unrecognised but common form of biological stress in water bodies and soils.
Lipid biomolecules in silica sinters: indicators of microbial biodiversity
Authors: Pancost Richard D. , Pressley Sarah , Coleman Joanna M. , Benning Liane G. , Mountain B. W. 
Published: December 2004

SummaryTo explore further the diversity of the microorganisms and their relationship with geothermal sinters, we examined the lipids preserved in six sinters associated with four different hot spring (58–82°C) areas of the Taupo Volcanic Zone (TVZ), New Zealand. These sinters contain microbial remains, but the process of mineralization has rendered them largely unidentifiable. Dominant lipids include free fatty acids, 1,2‐diacylglycerophospholipids, 1,2‐di‐O‐alkylglycerols, glycerol dialkylglycerol tetraethers and 1‐O‐alkylglycerols. These confirm the presence and, in some cases, high abundances of bacteria in all six sinters and archaea in four of the six sinter samples; in addition, the presence of novel macrocyclic diethers and unusual distributions of monoethers and diethers suggest the presence of previously uncharacterized bacteria. The lipid distributions are also markedly dissimilar among the four sites; for example, novel macrocyclic diethers are restricted to the Rotokawa samples while particularly abundant monoethers occur only in the Orakei Korako sample. Thus, biomarkers can provide crucial insight into the complex community structure of thermophilic microorganisms, including both archaea and bacteria, involved with biogenic silica sinter formation.
Spontaneous Oscillations in Cerebral Blood Flow Velocity Give Evidence of Different Autonomic Dysfunctions in Various Types of Headache
Authors: Sliwka U. , Harscher S. , Diehl R.R. , Van Schayck R. , Niesen W.D. , Weiller C. 
Published: December 2004

Objectives.—Our objectives were to determine if: (1) patients with migraine have B wave abnormalities in comparison to normal controls and patients with chronic tension headache and (2) patients with chronic tension headache have an imbalance in autonomic activity that is reflected in differences in Mayer wave activity in comparison to normal controls.Background.—B waves and Mayer waves are spontaneous oscillations in cerebral blood flow velocity with a frequency of 0.5 to 3 or 4 to 7 cycles per minute, respectively, and can be measured by transcranial Doppler sonography. There is experimental evidence that B waves are generated by certain brain stem nuclei which modulate the lumen of the small intracerebral vessels via monoaminergic nerve endings. In contrast, Mayer waves in cerebral blood flow velocity have no central generator but mirror the Mayer waves in arterial blood pressure which represent peripheral autonomic activity. Migraine may be attributed to a neurotransmitter imbalance in brain stem nuclei. Dysfunctions of the peripheral autonomic nervous system are known in patients with chronic tension headache.Methods.—Using bilateral transcranial Doppler monitoring of the middle cerebral artery B waves and Mayer waves were studied in 30 patients with migraine without aura, 28 subjects with tension‐type headache, and 30 normal controls. Coefficient of variation as a quantitative parameter for amplitude of waves and the mean frequency were calculated from the envelope curves of the Doppler spectra.Results.—The coefficient of variation of B waves was higher in migrainous patients compared with patients with tension‐type headache and normal controls (P<.05), indicating an increase in activity of brain stem nuclei in migraine only. Patients with chronic tension headaches had lower values for Mayer wave activity in comparison with normal controls (P<.05), a sign of an impairment of sympathetic activity.Conclusions.—Our data support the dysfunction of the brain stem monoaminergic/serotonergic system in migraine. In contrast, patients with chronic tension headache have an autonomic dysfunction of peripheral origin presenting as a decrease of sympathetic activity.
Electroanatomic Versus Fluoroscopic Mapping for Catheter Ablation Procedures:
Authors: SPORTON SIMON C. , EARLEY MARK J. , NATHAN ANTHONY W. , SCHILLING RICHARD J. 
Published: December 2004

Introduction: The aim of this prospective randomized study was to compare the routine use of electroanatomic imaging (CARTO) with that of conventional fluoroscopically guided activation mapping (conventional) in an unselected population referred for catheter ablation. We sought to compare the two approaches with respect to procedure outcome and duration, radiation exposure, and cost. Methods and Results: All patients undergoing catheter ablation (with the exception of complete AV nodal ablation) were prospectively randomized to either a CARTO or conventional procedure for mapping and ablation. One hundred two patients were randomized. Acute procedural success was similar with either strategy (CARTO vs conventional 43/47 vs 51/55, P > 0.5), as was procedure duration (144 [58] vs 125 [48] min, P = 0.07 (mean [SD]). CARTO was associated with a substantial reduction in fluoroscopy time (9.3 [7.6] vs 28.8 [19.5] min, P < 0.001) and radiation dose (6.2 [6.1] vs 20.8 [32.7] Gray, P = 0.003). CARTO cases used fewer catheters (2.5 [0.7] vs 4.4 [1.1], P < 0.001), but catheter costs were higher (13.8 vs 9.3 units, P < 0.001, where one unit is equivalent to the cost of a nonsteerable quadripolar catheter). Conclusion: For all catheter ablation procedures, even when a center's “learning curve” for CARTO is included, procedure duration and outcome are similar for CARTO and conventional procedures. CARTO is associated with drastically reduced fluoroscopy time and radiation dose. Although fewer catheters are used with CARTO, catheter costs remain higher. (J Cardiovasc Electrophysiol, Vol. 15, pp. 310‐315, March 2004)
New Multiplex PCR for Rapid Detection of Isoniazid-Resistant
Mycobacterium tuberculosis
Clinical Isolates
Authors: Herrera-León Laura , Molina Tamara , Saíz Pilar , Sáez-Nieto Juan Antonio , Jiménez Maria Soledad 
Published: December 2004

ABSTRACT

In this study, we describe a multiplex PCR to detect a AGC→ACC (serine to threonine) mutation in the
katG
gene and a −15 C-to-T substitution (
inhA
C−15T
) at the 5′ end of a presumed ribosome binding site in the promoter of the
mabA
-
inhA
operon. These mutations have been reported in the majority of previous studies as the most frequent mutations involved in the resistance to isoniazid (INH) of
Mycobacterium tuberculosis
clinical strains with high levels of resistance. The method was optimized and validated after an analysis of 30
M. tuberculosis
clinical isolates with known sequences of the relevant part of the
katG
gene and the regulatory region of the
mabA
-
inhA
operon. We analyzed 297 INH-resistant
M. tuberculosis
isolates collected in Spain from 1996 to 2003 by PCR-restriction fragment length polymorphism (using the
katG
gene), DNA sequencing, and the newly developed multiplex PCR. The results were concordant for all 297 isolates tested. The analysis revealed that 204 (68.7%) of the isolates carried one or both of the mutations. This finding suggests that with further development this multiplex PCR will be able to detect the majority of the INH-resistant
M. tuberculosis
clinical isolates from Spain and other countries where a high frequency of similar mutations occur.
Binding Site of the Bridged Macrolides in the
Escherichia coli
Ribosome
Authors: Xiong Liqun , Korkhin Yakov , Mankin Alexander S. 
Published: December 2004

ABSTRACT

Ketolides represent the latest group of macrolide antibiotics. Tight binding of ketolides to the ribosome appears to correlate with the presence of an extended alkyl-aryl side chain. Recently developed 6,11-bridged bicyclic ketolides extend the spectrum of platforms used to generate new potent macrolides with extended alkyl-aryl side chains. The purpose of the present study was to characterize the site of binding and the action of bridged macrolides in the ribosomes of
Escherichia coli
. All the bridged macrolides investigated efficiently protected A2058 and A2059 in domain V of 23S rRNA from modification by dimethyl sulfate and U2609 from modification by carbodiimide. In addition, bridged macrolides that carry extended alkyl-aryl side chains protruding from the 6,11 bridge protected A752 in helix 35 of domain II of 23S rRNA from modification by dimethyl sulfate. Bridged macrolides efficiently displaced erythromycin from the ribosome in a competition binding assay. The A2058G mutation in 23S rRNA conferred resistance to the bridged macrolides. The U2609C mutation, which renders
E. coli
resistant to the previously studied ketolides telithromycin and cethromycin, barely affected cell susceptibility to the bridged macrolides used in this study. The results of the biochemical and genetic studies indicate that in the
E. coli
ribosome, bridged macrolides bind in the nascent peptide exit tunnel at the site previously described for other macrolide antibiotics. The presence of the side chain promotes the formation of specific interactions with the helix 35 of 23S rRNA.
Drug Resistance Mutations in the Nucleotide Binding Pocket of Human Immunodeficiency Virus Type 1 Reverse Transcriptase Differentially Affect the Phosphorolysis-Dependent Primer Unblocking Activity in the Presence of Stavudine and Zidovudine and Its Inhibition by Efavirenz
Authors: Crespan Emmanuele , Locatelli Giada A. , Cancio Reynel , Hübscher Ulrich , Spadari Silvio , Maga Giovanni 
Published: December 2004

ABSTRACTHuman immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) derivatives with D113E, Y115F, F116Y, Q151E/N, and M184V mutations were studied for their phosphorolysis-mediated resistance to the nucleoside RT inhibitors (NRTIs) zidovudine and stavudine and for their inhibition by the nonnucleoside analogs (NNRTIs) efavirenz and nevirapine. The results presented here indicate that these single amino acid substitutions within the nucleotide binding pocket of the viral RT can independently affect different enzymatic properties, such as catalytic efficiency, drug binding, and phosphorolytic activity. Moreover, small local alterations of the physicochemical properties of the microenvironment around the active site can have profound effects on some NRTIs while hardly affecting other ones. In conclusion, even though different mutations within the nucleotide binding pocket of HIV-1 RT can result in a common phenotype (i.e., drug resistance), the molecular mechanisms underlying this phenotype can be very different. Moreover, the same mutation can give rise to different phenotypes depending on the nature of the substrates and/or inhibitors.