bluuebunny/crossref_metadata_2025_split huggingface dataset:
Association of peptic ulcer with increased expression of Lewis antigens, but not vacuolating cytotoxin activity or babA2 gene status, in Helicobacter pylori strains from China
Authors: ZHENG Peng Yuan , TANG Fu Ai , QI Yuan Ming , LI Jian 
Published: January 2006

OBJECTIVE:  Controversies exist regarding the virulence factors, such as vacA, babA2 and Lewis blood group antigens, of Western and Asian strains of Helicobacter pylori. The aim of the present study was to determine the significance of these potential virulence factors in the Chinese population.METHODS:  Seventy‐two strains of H. pylori isolated from patients in Zhengzhou, China, including 43 cases of peptic ulcer (PU) and 29 cases of chronic gastritis, were determined. Vacuolating cytotoxin assay was performed by HeLa cells. The expression of Le blood group antigens (Lea, Leb, Lex and Ley) was performed by enzyme‐linked immunosorbent assay (ELISA). babA2 gene was identified by polymerase chain reaction. Frequencies were compared using two‐tailed Fisher's exact test. Cytotoxin activities were compared using Spearman's rank correction test.RESULTS:  Vacuolating cytotoxin activity was detected in 61 of the 72 strains (84.7%), but there was no significant difference in vacuolating cytotoxin activity (83.7% vs 86.2%, P = 0.821) or titer (4.4 ± 3.8 vs 4.2 ± 4.1, P = 0.876) between the PU and gastritis strains. Significantly more PU strains expressed two or more Lewis antigens (Lex, Ley, Lea or Leb) than strains from the chronic gastritis patients (90.7% vs 65.5%, P = 0.029). Of the 43 strains from PU patients, 17 (39.5%) were positive for babA2, compared with 11 (38.5%) of the 29 strains from gastritis patients (P = 0.924). There was no significant difference in the vacuolating cytotoxin activity or titer between strains expressing two or more Lewis antigens and less than two antigens (84.5% vs 85.7%, P = 1.000; 4.4 ± 4.2 vs 4.3 ± 3.2, P = 0.965). Of the 72 H. pylori strains, 28 were babA2 positive, of which 24 were cytotoxic, compared with 37 of 44 babA2‐negative strains (P = 1.000).CONCLUSION:  The present study suggests that PU is associated with increased Lewis antigen expression, but not vacuolating cytotoxin production or the presence of babA2, in the H. pylori strains in the Chinese population.
Anp32e/Cpd1 regulates protein phosphatase 2A activity at synapses during synaptogenesis
Authors: Costanzo Roxana V. , Vilá‐Ortíz Guillermo J. , Perandones Claudia , Carminatti Héctor , Matilla Antoni , Radrizzani Martín 
Published: January 2006

AbstractAnp32e/Cpd1, a member of the acidic nuclear phosphoprotein (Anp)32 family, is characterized by the presence of an amino terminal domain containing four leucine‐rich repeats and a carboxyl‐terminal low‐compositional complexity acidic region. In previous studies performed to understand the biological role of Anp32e/Cpd1, we showed a predominant presence of Anp32e/Cpd1 in the nucleus. However, when Anp32e/Cpd1 is in the cytoplasm, it co‐localizes spatially with protein phosphatase 2A (PP2A) near cell membranes, far from the synapses. In the present work, we show that Anp32e/Cpd1 is also present as a membrane‐bound 74/76‐kDa protein with a widespread distribution in the brain. We reveal that the expression, synthesis and half‐life of this high‐molecular‐weight form of Anp32e/Cpd1 are spatially and temporally correlated with the cerebellar synaptogenesis period. We demonstrate that synaptic Anp32e/Cpd1 co‐localizes, interacts and inhibits PP2A activity, and that phosphorylation of Anp32/Cpd1 is required for the Anp32e–PP2A interaction. Also, subcellular localization was shown with electronic microscopy. Finally, we examine Anp32e/Cpd1 and PP2A distribution in two ataxic mutant models, weaver and staggerer, and show that their co‐localization in Purkinje cell dendrites depends on parallel fibre/Purkinje cell contacts. Based on these observations, we propose that Anp32e/Cpd1 mediates synaptogenesis process by modulating PP2A activity.
Reduced ethanol response in the alcohol‐preferring RHA rats and neuropeptide mRNAs in relevant structures
Authors: Guitart‐Masip Marc , Giménez‐Llort Lydia , Fernández‐Teruel Albert , Cañete Toni , Tobeña Adolf , Ögren Sven Ove , Terenius Lars , Johansson Björn 
Published: January 2006

AbstractRoman rat strains, genetically selected for high (RHA) or low (RLA) active avoidance acquisition in the two‐way shuttle box, differ in dopaminergic activity. These two strains appear to be a valid laboratory model of divergent sensation/novelty and substance‐seeking profiles. RHA rats show higher ethanol intake and preference than do RLA rats, and it was suggested that RHA rats are more tolerant than RLA to the effects of alcohol. In the hole‐board test, we found that the non‐alcohol‐preferring RLA rats showed enhanced responsiveness to the stimulatory effects of intraperitoneal administration of 0.25 g/kg ethanol when compared with RHA rats. In situ hybridization analysis showed higher levels of preprodynorphin in the accumbens shell and higher levels of preproenkephalin in the cingulate cortex in RHA rats. RLA rats showed higher levels of enkephalin gene transcripts in restricted areas of the dorsal striatum. Finally, differences in cholecystokinin gene transcript, suggestive of a different arrangement of certain interneurons, were found in different cortical areas. The differences in peptide gene expression found between the two strains might reflect the differences in alcohol preference and sensitivity. RHA rats may have more predictive value than other rodent alcoholism models, as high initial tolerance to ethanol is a risk factor for alcoholism in humans.
Medial prefrontal cortex NMDA receptors and nitric oxide modulate the parasympathetic component of the baroreflex
Authors: Resstel L. B. M. , Corrêa F. M. A. 
Published: January 2006

AbstractThe ventral portion of the medial prefrontal cortex (vMPFC) is involved in the modulation of the parasympathetic component of the baroreflex. In the present study, we verified the effect of blockade of vMPFC glutamatergic receptors and nitric oxide synthases (NOS) on the parasympathetic component of baroreflex in awake rats. Bilateral microinjection of the non‐selective ionotropic glutamate antagonist kynurenic acid (KYN) into the vMPFC caused a shift of the threshold of reflex bradycardia toward higher pressures in response to increases in mean arterial pressure (MAP) caused by intravenous infusion of phenylephrine, thus indicating a tonic facilitatory influence action of vMPFC glutamate receptors on the parasympathetic component of the baroreflex. The effect of blockade of vMPFC‐NMDA receptors by AP7 was similar to that observed after KYN, suggesting mediation via NMDA receptors. Pretreatment with the NOS inhibitor L‐NAME or the specific neural NOS (nNOS)Nω‐propyl‐l‐arginine microinjected in the vMPFC caused a shift of the reflex threshold toward higher pressures that was similar to that observed after blockade of NMDA receptors, thus indicating participation of the NO/NMDA‐receptor pathway in the vMPFC modulation of the parasympathetic component of the baroreflex. In conclusion, our data indicate that glutamatergic neurotransmission in the vMPFC has a tonic facilitatory influence on the parasympathetic component of the baroreflex. Because local treatment with either the nNOS inhibitorNω‐propyl‐l‐arginine or the specific NMDA antagonist AP7 had similar effects on the baroreflex, it is also suggested that this modulation involves an NMDA–NO interaction within the vMPFC.
Evidence for a functional role of GABACreceptors in the rat mature hippocampus
Authors: Alakuijala Anniina , Alakuijala Jyrki , Pasternack Michael 
Published: January 2006

AbstractBoth γ‐aminobutyric acid (GABA)Creceptor subunit mRNA and protein are expressed in the stratum pyramidale in the CA1 area of the adult rat hippocampus, but so far no conclusive evidence about functional hippocampal GABACreceptors has been presented. Here, the contribution of GABACreceptors to stimulus‐evoked postsynaptic potentials was studied in the hippocampal CA1 area with extracellular and intracellular recordings at the age range of 21–47 postnatal days. Activation of GABACreceptors with the specific agonistcis‐4‐aminocrotonic acid (CACA) suppressed postsynaptic excitability and increased the membrane conductance. The GABACreceptor antagonist 1,2,5,6‐tetrahydropyridine‐4‐ylmethylphosphinic acid (TPMPA), but not the GABAAreceptor antagonist bicuculline, inhibited the effects of CACA. GABA‐mediated long‐lasting depolarizing responses evoked by high‐frequency stimulation of local inhibitory interneurons in the CA1 area in the presence of ionotropic glutamate receptor and GABABreceptor blockers were prolonged by TPMPA, indicating that GABACreceptors are activated under these conditions. For weaker stimulation, the effect of TPMPA was enhanced after GABA uptake was inhibited. Our data demonstrate that GABACreceptors can be activated by endogenous synaptic transmitter release following strong stimulation or under conditions of reduced GABA uptake. The lack of GABACreceptor activation by less intensive stimulation under control conditions suggests that these receptors are extrasynaptic and activated via spillover of synaptically released GABA.
Visuospatial reorienting signals in the human temporo‐parietal junction are independent of response selection
Authors: Astafiev Serguei V. , Shulman Gordon L. , Corbetta Maurizio 
Published: January 2006

AbstractThis study contrasts visuospatial reorienting and response selection signals in the right temporo‐parietal junction (TPJ) with functional magnetic resonance imaging. The overall goal was to investigate whether spatial orienting signals and motor signals interacted or were independent in TPJ. The right TPJ showed a greater response to targets at invalidly rather than validly cued locations, but no significant modulation from the effector used to respond. We suggest that TPJ may work as a modality‐independent ‘circuit breaker’ for the dorsal fronto‐parietal attention system, directing attention to salient events and enabling a variety of responses to those events.
Propofol block ofIhcontributes to the suppression of neuronal excitability and rhythmic burst firing in thalamocortical neurons
Authors: Ying Shui‐Wang , Abbas Syed Y. , Harrison Neil L. , Goldstein Peter A. 
Published: January 2006

AbstractAlthough the depressant effects of the general anesthetic propofol on thalamocortical relay neurons clearly involve γ‐aminobutyric acid (GABA)Areceptors, other mechanisms may be involved. The hyperpolarization‐activated cation current (Ih) regulates excitability and rhythmic firing in thalamocortical relay neurons in the ventrobasal (VB) complex of the thalamus. Here we investigated the effects of propofol onIh‐related functionin vitroandin vivo. In whole‐cell current‐clamp recordings from VB neurons in mouse (P23–35) brain slices, propofol markedly reduced the voltage sag and low‐threshold rebound excitation that are characteristic of the activation ofIh. In whole‐cell voltage‐clamp recordings, propofol suppressed theIhconductance and slowed the kinetics of activation. The block ofIhby propofol was associated with decreased regularity and frequency of δ‐oscillations in VB neurons. The principal source of theIhcurrent in these neurons is the hyperpolarization‐activated cyclic nucleotide‐gated (HCN) type 2 channel. In human embryonic kidney (HEK)293 cells expressing recombinant mouse HCN2 channels, propofol decreasedIhand slowed the rate of channel activation. We also investigated whether propofol might have persistent effects on thalamic excitability in the mouse. Three hours following an injection of propofol sufficient to produce loss‐of‐righting reflex in mice (P35),Ihwas decreased, and this was accompanied by a corresponding decrease in HCN2 and HCN4 immunoreactivity in thalamocortical neuronsin vivo. These results suggest that suppression ofIhmay contribute to the inhibition of thalamocortical activity during propofol anesthesia. Longer‐term effects represent a novel form of propofol‐mediated regulation ofIh.
A null model of exotic plant diversity tested with exotic and native species–area relationships
Authors: Stark Scott C. , Bunker Daniel E. , Carson Walter P. 
Published: January 2006

AbstractAt large spatial scales, exotic and native plant diversity exhibit a strong positive relationship. This may occur because exotic and native species respond similarly to processes that influence diversity over large geographical areas. To test this hypothesis, we compared exotic and native species–area relationships within six North American ecoregions. We predicted and found that within ecoregions the ratio of exotic to native species richness remains constant with increasing area. Furthermore, we predicted that areas with more native species than predicted by the species–area relationship would have proportionally more exotics as well. We did find that these exotic and native deviations were highly correlated, but areas that were good (or bad) for native plants were even better (or worse) for exotics. Similar processes appear to influence exotic and native plant diversity but the degree of this influence may differ with site quality.
Niche breadth, competitive strength and range size of tree species: a trade‐off based framework to understand species distribution
Authors: Morin Xavier , Chuine Isabelle 
Published: January 2006

AbstractUnderstanding the mechanisms causing latitudinal gradients in species richness and species range size is a central issue in ecology, particularly in the current context of global climate change. Different hypotheses have been put forward to explain these patterns, emphasizing climatic variability, energy availability and competition. Here we show, using a comparative analysis controlling for phylogeny on 234 temperate/boreal tree species, that these hypotheses can be included into a single framework in an attempt to explain latitudinal gradients in species range size. We find that species tend to have larger ranges when (i) closer to the poles, (ii) successionally seral, (iii) having small and light seeds, and (iv) having short generations. The patterns can simply be explained by energy constraints associated with different life‐history strategies. Overall, these findings shed a new light on our understanding of species distribution and biodiversity patterns, bringing new insights into underlying large‐scale evolutionary processes.
Local and regional scale recovery of Diadema promotes recruitment of scleractinian corals
Authors: Carpenter Robert C. , Edmunds Peter J. 
Published: January 2006

AbstractThe phase change from coral to macroalgal dominance on many Caribbean reefs was exacerbated by the mortality of the echinoid Diadema antillarum in 1983–1984, and until recently, this sea urchin has remained rare on reefs throughout the western Atlantic. By the late 1990s, Diadema started to reappear in large numbers on some Jamaican reefs, and by 2000, the high densities were correlated with significantly greater abundances of juvenile corals. Here, we show that dense populations of Diadema now occur over a multi‐kilometre‐wide scale at six locations scattered along a 4100 km arc across the entire Caribbean. In all cases, these dense populations are found in shallow water (< 6 m depth) on outer reef communities and are associated with reduced macroalgal cover and enhanced coral recruitment. We conclude that population recovery of Diadema is occurring at both local and regional scales, and that grazing by this echinoid is creating conditions favouring the recruitment of corals.
Can non‐directional male mating preferences facilitate honest female ornamentation?
Authors: Chenoweth Stephen F. , Doughty Paul , Kokko Hanna 
Published: January 2006

AbstractRecent studies have demonstrated male mate choice for female ornaments in species without sex‐role reversal. Despite these empirical findings, little is known about the adaptive dynamics of female signalling, in particular the evolution of male mating preferences. The evolution of traits that signal mate quality is more complex in females than in males because females usually provide the bulk of resources for the developing offspring. Here, we investigate the evolution of male mating preferences using a mathematical model which: (i) specifically accounts for the fact that females must trade‐off resources invested in ornaments with reproduction; and (ii) allows male mating preferences to evolve a non‐directional shape. The optimal adaptive strategy for males is to develop stabilizing mating preferences for female display traits to avoid females that either invests too many or too few resources in ornamentation. However, the evolutionary stability of this prediction is dependent upon the level of error made by females when allocating resources to either signal or fecundity.
Mixed biodiversity benefits of agri‐environment schemes in five European countries
Authors: Kleijn D. , Baquero R. A. , Clough Y. , Díaz M. , De Esteban J. , Fernández F. , Gabriel D. , Herzog F. , Holzschuh A. , Jöhl R. , Knop E. , Kruess A. , Marshall E. J. P. , Steffan‐Dewenter I. , Tscharntke T. , Verhulst J. , West T. M. , Yela J. L. 
Published: January 2006

AbstractAgri‐environment schemes are an increasingly important tool for the maintenance and restoration of farmland biodiversity in Europe but their ecological effects are poorly known. Scheme design is partly based on non‐ecological considerations and poses important restrictions on evaluation studies. We describe a robust approach to evaluate agri‐environment schemes and use it to evaluate the biodiversity effects of agri‐environment schemes in five European countries. We compared species density of vascular plants, birds, bees, grasshoppers and crickets, and spiders on 202 paired fields, one with an agri‐environment scheme, the other conventionally managed. In all countries, agri‐environment schemes had marginal to moderately positive effects on biodiversity. However, uncommon species benefited in only two of five countries and species listed in Red Data Books rarely benefited from agri‐environment schemes. Scheme objectives may need to differentiate between biodiversity of common species that can be enhanced with relatively simple modifications in farming practices and diversity or abundance of endangered species which require more elaborate conservation measures.
Linking species–area and species–energy relationships in Drosophila microcosms
Authors: Hurlbert Allen H. 
Published: January 2006

AbstractResource availability is an important constraint on community structure. Some authors have suggested it conceptually links two of the most basic patterns in ecology, the species–area relationship and the latitudinal gradient in species richness. I present the first experimental test of this conjecture, by manipulating both the area and resource concentration of artificial larval drosophilid fly habitats and then allowing colonization from a natural species pool. Both the abundance and species richness of these habitats depended upon the total quantity of resources available, regardless of whether those resources were contained within smaller high‐quality habitats or larger poor‐quality habitats. While the intercepts of species–area relationships varied with resource concentration, they all collapsed onto the same species–energy curve. These results support the view that energetic constraints are of fundamental importance in structuring ecological communities, and that such constraints may even help explain ecological patterns such as the species–area relationship that do not explicitly address resource availability.
The impacts of climate change in coastal marine systems
Authors: Harley Christopher D. G. , Randall Hughes A. , Hultgren Kristin M. , Miner Benjamin G. , Sorte Cascade J. B. , Thornber Carol S. , Rodriguez Laura F. , Tomanek Lars , Williams Susan L. 
Published: January 2006

AbstractAnthropogenically induced global climate change has profound implications for marine ecosystems and the economic and social systems that depend upon them. The relationship between temperature and individual performance is reasonably well understood, and much climate‐related research has focused on potential shifts in distribution and abundance driven directly by temperature. However, recent work has revealed that both abiotic changes and biological responses in the ocean will be substantially more complex. For example, changes in ocean chemistry may be more important than changes in temperature for the performance and survival of many organisms. Ocean circulation, which drives larval transport, will also change, with important consequences for population dynamics. Furthermore, climatic impacts on one or a few ‘leverage species’ may result in sweeping community‐level changes. Finally, synergistic effects between climate and other anthropogenic variables, particularly fishing pressure, will likely exacerbate climate‐induced changes. Efforts to manage and conserve living marine systems in the face of climate change will require improvements to the existing predictive framework. Key directions for future research include identifying key demographic transitions that influence population dynamics, predicting changes in the community‐level impacts of ecologically dominant species, incorporating populations’ ability to evolve (adapt), and understanding the scales over which climate will change and living systems will respond.
Ecosystem engineers as selective agents: the effects of leaf litter on emergence time and early growth in Impatiens capensis
Authors: Stinchcombe John R. , Schmitt Johanna 
Published: January 2006

AbstractBy physically modifying the abiotic environment, ecosystem engineers can have dramatic effects on the distribution and abundance of species in a community. However, ecosystem engineering can also change the selective environment and evolutionary dynamics of affected species, although this remains relatively understudied. Here, we examine the potential for an ecosystem engineer – oak trees – to affect the evolutionary dynamics of the herbaceous, understory annual, Impatiens capensis, through leaf litter deposition. Using a quantitative genetic experimental approach, we found that: (i) the presence of leaf litter significantly affected a suite of germination, growth and phenological traits in I. capensis; (ii) I. capensis does not exhibit performance trade‐offs across litter and bare soil environments in the form of negative across‐environment genetic correlations; (iii) the presence or absence of leaf litter significantly alters the pattern of natural selection germination timing and hypocotyl length; and (iv) the frequency of leaf litter environments can dramatically change which combinations of hypocotyl length lead to highest mean fitness across both bare soil and leaf litter environments. More generally, our results demonstrate the potential for ecosystem engineers to alter both the ecological and the evolutionary dynamics of the species they affect.