bluuebunny/crossref_metadata_2025 huggingface dataset:
Madagascar: an unexpected hotspot of socialAnelosimusspider diversity (Araneae: Theridiidae)
Authors: Agnarsson Ingi , Kuntner Matjaž
Published: November 2005

Abstract. The spider genusAnelosimusSimon, 1891 (Theridiidae) currently contains over forty described species, found worldwide in tropical to warm temperate areas. AmericanAnelosimusare all social, a rare trait among spiders, but social behaviour has not been reported forAnelosimusspecies elsewhere. Old WorldAnelosimusare poorly known, both behaviourally and taxonomically, and noAnelosimusspecies have yet been described from sub‐Saharan Africa or Madagascar. Based on a preliminary phylogenetic analysis we predicted sociality in an undescribed Madagascar species because it grouped among social New World species. An expedition to Madagascar then found no less than five undescribed periodic‐social (subsocial)Anelosimusspecies in Périnet reserve. A sixth species from the same locality is known from museum specimens and theAnelosimusdiversity of Périnet is comparable with the most diverse single locality in the Americas. Subsocial species play a key role in understanding the evolution of permanent sociality (quasisociality). This increased pool of available subsocial study species demonstrates the utility of phylogenies as predictors of traits in species thus far unstudied. Here,A. andasibesp.n.,A. mayAgnarssonsp.n.,A. nazarianisp.n.,A. salleesp.n.,A. salutsp.n.andA. vondronasp.n.are described.Anelosimus locketiRoberts, 1977 from Aldabra Atoll is a junior synonym ofA. decaryi(Fage, 1930) comb.n. from Madagascar. Preliminary data on the behaviour of the new species are given, indicating a level of sociality similar to the AmericanA.‘arizona’1. The phylogenetic analysis supports the monophyly of the Madagascar group and places it as sister to a clade containing theeximiuslineage from the Americas, and a pair of undescribed Tanzanian species.
Delimitation difficulties in species splits: a morphometric case study on the Euxoa tritici complex (Lepidoptera, Noctuidae)
Authors: Mutanen Marko
Published: November 2005

Abstract.  Genital characteristics tend to vary greatly between Lepidoptera species, providing helpful features for species delimitation. The differences between species are usually remarkable and suspicions about species identity never arise. However, fairly often, and possibly increasingly, taxa are elevated to species rank on the basis of very slight morphological differences, often without quantitative support. Euxoa tritici (Linnaeus) is a typical example of a variable species split into several morphologically similar species. The present study tested whether the diagnostic genital characters of the current classification, based on nonquantitative methodology, provide safe identification of species. Both traditional distance morphometrics as well as modern geometric morphometrics, which also enables quantitative shape exploration, were used. Moreover, whether the study specimens can be unambiguously categorized into several species with visual comparisons was tested independently using four specialist entomologists. Genital types of several named species as well as considerable variation in genitalia were found, but no support was found for the presence of several morphologically distinguishable species with quantitative morphometric analyses. Neither were study specimens categorized unambiguously by specialists. The results suggest that pure visual comparisons may lead to unsound taxonomic conclusions and that a quantitative approach in critical cases should be used more frequently.
How do insect nuclear ribosomal genes compare to protein‐coding genes in phylogenetic utility and nucleotide substitution patterns?
Authors: Danforth Bryan N. , Lin Chung‐Ping , Fang Jennifer
Published: November 2005

Abstract.  The expanding data set on insect molecular systematics allows examination of phylogenetic performance and molecular evolution of different types of gene. Studies combining more than one gene in the same analysis allow examination of the relative contribution and performance of each gene partition and can help inform gene choice for resolving deep and/or problematic divergences. We compared results obtained from analyses of twelve insect data sets in which authors combined one or more nuclear ribosomal genes (28S and/or 18S) with one or more protein‐coding genes [elongation factor‐1α (EF‐1α), histone H3, carbamoylphosphate synthetase domain (CPS domain of CAD, or rudimentary), long‐wavelength rhodopsin (LW opsin), glucose‐6‐phosphate dehydrogenase (G6pd), phosphoenolpyruvate carboxykinase (PEPCK), arginine kinase, and white]. Data sets examined spanned eight orders of insects (Odonata, Ephemeroptera, Hemiptera, Coleoptera, Trichoptera, Lepidoptera, Diptera and Hymenoptera), providing a broad range of divergence times and taxonomic levels. We estimated the phylogenetic utility of the individual genes (using parsimony methods) and characterized the nucleotide substitution patterns (using Bayesian methods) to ask which type of data is preferable for phylogenetic analysis in insects. Nuclear ribosomal and protein coding genes differed little in our measures of phylogenetic performance and patterns of nucleotide substitution. We recommend combining nuclear ribosomal gene data with nuclear protein‐coding gene data because each data set has distinct advantages. We do not recommend using mitochondrial genes for higher‐level studies of insect phylogeny because reviewed studies demonstrate substitution patterns that lead to high levels of homoplasy.
Association of insect life stages using DNA sequences: the larvae of Philodytes umbrinus (Motschulsky) (Coleoptera: Dytiscidae)
Authors: Miller Kelly B. , Alarie Yves , Wolfe G. William , Whiting Michael F.
Published: November 2005

Abstract.  Insect life stages are known imperfectly in many cases, and classifications are based often on only one or a few semaphoronts of a species. This is unfortunate as information in alternative life stages often is useful for scientific study. Although recent examples of DNA in taxonomy have emphasized the identification of indistinguishable species, such sequence data facilitate the association of life history stages and hold considerable promise in phylogenetic analysis, evolutionary studies, diagnostics, etc. These concepts are discussed here and an example is provided from diving beetles (Dytiscidae: Coleoptera). Three unknown larval specimens of an apparent species of Laccophilinae collected in Namibia were associated with the species Philodytes umbrinus (Motschulsky) using DNA sequence data. An 806‐bp portion of the gene cytochrome oxidase I was sequenced from the unknown larvae. Several identified adult specimens of species of Laccophilinae from Namibia were also sequenced, including two P. umbrinus specimens and specimens from four Laccophilus Leach species. Additional species of Laccophilus from other areas of the world also were sequenced, as were specimens of Agabetes acuductus (Harris), Australphilus saltus Watts, Neptosternus boukali Hendrich & Balke and a species of Laccodytes Régimbart. Parsimony analysis resulted in two most parsimonious trees with the unknown larva unambiguously resolved in a group with both adult specimens of P. umbrinus (bootstrap value = 100%). The average pairwise p‐distance between the unknown larva and adult P. umbrinus specimens averaged 0.09% (0–0.14%), compared with an average divergence between other conspecifics in the analysis of 0.24% (0–0.82%) and an overall average divergence between species of 13.49% (1.90–19.86%). Based on this, the unknown larvae were assigned to P. umbrinus. The larvae are diagnosed and described and their relationship with other Laccophilinae is discussed.
Characterization of a strawberry late‐expressed and fruit‐specific peptide methionine sulphoxide reductase
Authors: Lopez Andrés Pedraza , Portales Rosario Blanco , López‐Ráez Juan Antonio , Medina‐Escobar Nieves , Blanco Juan Muñoz , Franco Antonio Rodríguez
Published: November 2005

We have cloned and characterized a cDNA clone, called Fapmsr, coding for a putative peptide methionine sulphoxide [Met(O)] reductase (PMSR, EC 1.8.4.6) from strawberry fruits (Fragaria x ananassa). This gene is involved in the repair of inactive peptides and proteins caused for the oxidation of methionine residues to Met(O). Expression of the Fapmsr was only detected in the receptacles of red mature fruits and not in young or immature fruits nor in other plant tissues such as flowers, leaves, runners, roots or achenes. Expression of the Fapmsr gene was activated in green immature fruits when achenes were removed from receptacles, and this was prevented by the application of exogenous auxins such as naphthaleneacetic acid. The enzyme produced and purified by cloning the strawberry cDNA in frame with the C‐terminal sequence of the glutathione S‐transferase gene can reduce free Met(O) to methionine as analysed by reverse phase high performance liquid chromatography. We have also set up a PMSR protection assay that demonstrates that this enzyme can protect in vivo against the damage produced by the addition of H2O2.
Long‐term plum pox virus infection produces an oxidative stress in a susceptible apricot,Prunus armeniaca, cultivar but not in a resistant cultivar
Authors: Hernández José Antonio , Díaz‐Vivancos Pedro , Rubio Manuel , Olmos Enrique , Ros‐Barceló Alfonso , Martínez‐Gómez Pedro
Published: November 2005

The effect of plum pox virus (PPV) infection on the response of some antioxidant enzymes was studied in two apricot cultivars, which behaved differently against PPV infection: cultivar Real Fino (susceptible) and cultivar Stark Early Orange (cv. SEO, resistant). In the susceptible cultivar, PPV produced a decrease inΦPSII,F′v/F′mandQp. PPV infection produced a drop inp‐hydroxy mercury benzoic acid (pHMB)‐sensitive ascorbate peroxidase, dehydroascorbate reductase and peroxidase in the soluble fraction from susceptible plants, whereas in the resistant apricot cultivar, pHMB‐insensitive ascorbate peroxidase, monodehydroascorbate reductase, glutathione reductase and superoxide dismutase increased. However, catalase decreased in the soluble fractions from both infected cultivars. Long‐term PPV infection also produced a decrease in the chloroplastic ascorbate–glutathione cycle enzymes only in the susceptible plants. As a consequence of PPV infection, an oxidative stress, indicated by an increase in lipid peroxidation and in protein oxidation, was produced only in the leaves from the susceptible cultivar which was also monitored by the diaminobenzidine peroxidase‐coupled H2O2probe. The loss ofΦPSII, indicative of activated oxygen species production, and the decrease in the levels of antioxidant enzymes in chloroplasts from susceptible plants could be responsible for the chlorosis symptoms observed. The results suggest that the higher antioxidant capacity showed by cv. SEO could be a consequence of a systemic acquired resistance induced by PPV penetration in stem tissue at the graft site and could be related, among other factors, to their resistance to PPV.
The role of ABF family bZIP class transcription factors in stress response
Authors: Kim Soo Young
Published: November 2005

Adverse environmental conditions, such as drought, high salinity and chilling/freezing, are major limiting factors of crop productivity worldwide. According to Boyer [Science 1982;218:443–448], approximately 70% of the genetic potential yield of major crops is lost by these environmental factors. Thus, understanding how plants respond to the ‘abiotic stresses’ is of agronomic importance. Being sessile, plants have the capability to perceive and respond adaptively to various abiotic stresses. The adaptive capability of plants is largely dependent on the plant hormone abscisic acid (ABA), which regulates, among others, the expression of numerous genes involved in stress adaptation. Extensive genetic and molecular studies have been carried out during the last decade or so, and, as a result, a large body of information is available on the regulatory components of ABA‐responsive gene expression under stress conditions. In this article, recent advances in the area are summarized, focusing on the regulatory components of ABA‐dependent stress‐responsive gene expression.
Brassinosteroid induction of AtACS4 encoding an auxin‐responsive 1‐aminocyclopropane‐1‐carboxylate synthase 4 in Arabidopsis seedlings
Authors: Joo Sunjoo , Seo Young Sam , Kim Sang Mi , Hong Dong Ki , Park Ky Young , Kim Woo Taek
Published: November 2005

Brassinosteroid (BR), an endogenous steroid growth regulator of higher plants, enhances expansion and division of the cell in a number of plant species. It has been recently reported that a shared auxin–BR signalling pathway is involved in the seedling growth in Arabidopsis. Here, we show that BR specifically enhanced the expression of AtACS4, which encodes an auxin‐responsive ACC synthase 4, by a distinct temporal induction mechanism compared with that of IAA in etiolated Arabidopsis seedlings. This BR induction of AtACS4 was undetectable in the light‐grown seedlings. In addition, BR failed to activate the AtACS4 gene in auxin‐resistant1 (axr1‐3) and auxin‐resistant2 (axr2‐1), both of which are auxin‐resistant mutants. Thus, it appears that there is a possible regulatory link between light, auxin and BR to control ethylene synthesis in Arabidopsis young seedlings. Analysis of transgenic Arabidopsis plants harbouring AtACS4::GUS fusion revealed the AtACS4 promoter‐driven GUS activity in the highly elongating zone of the hypocotyls in response to BR treatment. Furthermore, Arabidopsis plants homozygous for the T‐DNA insertion in the AtACS4 gene exhibited longer hypocotyls and roots than those of control seedlings. Taken together, these results suggest that the BR‐induced ethylene production may participate in the elongation growth response in early seedling development of Arabidopsis.
Evolution of sex-biased maternal effects in birds: II. Contrasting sex-specific oocyte clustering in native and recently established populations
Authors: Badyaev A. V. , Oh K. P. , Mui R.
Published: November 2005

In species that produce broods of multiple offspring, parents need to partition resources among simultaneously growing neonates that often differ in growth requirements. In birds, multiple ovarian follicles develop inside the female at the same time, resulting in a trade-off of resources among them and potentially limiting maternal ability for sex-specific allocation. We compared resource acquisition among oocytes in relation to their future sex and ovulation order in two populations of house finches with contrasting sex-biased maternal strategies. In a native Arizona population, where mothers do not bias offspring sex in relation to ovulation order, the male and female oocytes did not show sex-specific trade-offs of resources during growth and there was no evidence for spatial or temporal segregation of male and female oocytes in the ovary. In contrast, in a recently established Montana population where mothers strongly bias offspring sex in relation to ovulation order, we found evidence for both intra-sexual trade-offs among male and female oocytes and sex-specific clustering of oocytes in the ovary. We discuss the importance of sex-specific resource competition among offspring for the evolution of sex-ratio adjustment and sex-specific maternal resource allocation.
Changes in the levels of plant total phenols and free amino acids induced by two cereal aphids and effects on aphid fecundity
Authors: Eleftherianos I. , Vamvatsikos P. , Ward D. , Gravanis F.
Published: November 2005

Abstract:  Phenols and amino acids have previously been involved in the resistance of cereals to aphids. In the present study, the mean total concentrations of both compounds were quantitatively estimated from leaf‐tissue samples collected at three growth stages (third, fifth and seventh leaf stages) from maize and barley seedlings and then correlated with the mean 7‐day fecundity of Rhopalosiphum padi (L.) and Sitobion avenae (F.) (Homoptera, Aphididae) reared separately on the corresponding growth stages of each cereal. Results revealed an inverse correlation between the total concentration of each chemical in aphid‐infested maize and barley plants and the fecundity of each aphid on every growth stage of the cereals. Moreover, R. padi led to an increase in total amino acids when reared on maize or barley without affecting the phenol concentration, while S. avenae induced a decrease in phenol levels but did not change the total amino acids on each growth stage of the plants. The significance of these results for understanding potential differences in requirements of cereal aphids for host selection and acceptance are discussed.
Host‐plant acceptance and performance of Tetranychus urticae (Acari, Tetranychidae)
Authors: Greco N. M. , Pereyra P. C. , Guillade A.
Published: November 2005

Abstract:  Tetranychus urticae is a serious pest of several crops worldwide. It performs differentially on diverse host‐plant species. Because dispersion is mainly passive, the process of host‐plant selection should be viewed in terms of host‐plant acceptance and not in terms of host finding. The objectives of this study were to investigate: (1) the acceptance of strawberry (S) in comparison with onion (O), leek (L) and parsley (P) by T. urticae; and (2) the suitability of these host plants for the performance of T. urticae, in terms of fecundity and survival. Host‐plant acceptance was measured through females that settled on a test plant or females that left for another host plant. In another experiment, for a duration of 5 days, individual newly mated females were assigned to discs of each host plant and the fecundity, the maximum number of offspring obtained from one female that settled on the disc, the survival and the percentage of females that oviposited at least one egg were analysed. A choice test to measure the preference of females for different host plants was performed. Movements took place towards (S) from the three plants: (O), (L) and (P). Mites significantly moved to other places in the Petri dishes from leek‐origin discs. Dispersal of T. urticae from (S) to other host‐plant discs was similar for all plants. Mean fecundity was higher on (S) than on the other plants. The maximum number of offspring per female was highest on (S), lowest on (L) and (O), and intermediate on (P). Survival of females and percentage of females that laid at least one egg were independent of the host plant. The choice test showed that oviposition was higher on (S) and (P) and very poor on (L) and (O) and that more females settled on (S) and (P). Although mites migrated from parsley to strawberry, the first host plant has a higher acceptance of T. urticae in terms of maximum number of offspring per female than onion and leek, and a lower performance in terms of fecundity than strawberry. Parsley could be a good candidate for an associate plant in a strawberry crop; however, it needs more research under field conditions.
Do the learning needs of rural and urban general practitioners differ?
Authors: Allan James A. , Schaefer Di
Published: November 2005

Introduction:  The challenges of rural general practice have given rise to a separate rural training stream and a separate rural professional body. The differences are characterised by the nature of the work undertaken by rural GPs and reflected in the continuing medical education topic choices made when surveyed.

Methods:  In 2001 a survey was designed and distributed by the Royal Australian College of General Practitioners and Divisions of General Practice in South Australia and Northern Territory. The survey utilised a list of 104 topics. The topic choices of rural and urban GPs were compared.

Results:  The survey was distributed to approximately 1762 GPs and yielded 578 responses (33%). Rural GPs were more likely to select the following topics: Anaesthetics, Aboriginal Torres Strait Islander health, Population Health, Renal medicine, Cardiology, Teaching skills, Obstetrics, Neonates, Arrhythmias, Fracture management, Tropical medicine and Therapeutics. Urban GPs were more likely to select Menopause, Travel medicine and Palliative care (P < 0.05).

Discussion:  Many of the areas of difference reflected aspects of rural general practice. There were also many similarities in topic choices between these two groups.
Palliative care in the hinterlands: A description of existing services and doctors’ attitudes
Authors: Pereira Glenn J.
Published: November 2005

Objective:  To describe palliative care services as they exist in the hinterlands (towns away from regional centres) of Midwest New South Wales, including an estimation of the numbers of cases treated by local doctors, and the service they provide to their patients. Generalist doctors’ attitudes to palliative care are also explored, as this information is lacking in the literature but is important for service provision.

Design:  Descriptive survey.

Setting:  Rural primary care and district hospitals.

Participants:  Generalist doctors in hinterland areas.

Results:  In total, 38% (19/50) of surveys were returned. ‘Visiting rights’ to the district hospital were held by 78.9% of local doctors, and patients are admitted under the care of their own doctor for symptom control and terminal care, 94.1% and 76.5% of the time, respectively. All doctors surveyed perform home visits for terminally ill patients, and 68.4% make themselves routinely available after hours. Doctors surveyed estimated that they managed a mean of 8.4 deaths due to chronic illness in the past 12 months. Most (78.9%) said that they would continue to manage dying patients even if they had a choice, and they feel between moderately and very satisfied that they provide quality care. However, only 21.1% considered their undergraduate training in palliative medicine to be adequate, and all said that they would refer to a specialist service if it were available.

Conclusions:  Generalist rural doctors not only treat many dying patients, but also provide a continuity of care that is rarely seen in other settings. Proposals of models for ‘rural’ palliative care should, therefore, take this unique setting into account. One such suggestion is given in this article.
Patterns of home and community care service delivery to culturally and linguistically diverse residents of rural Victoria
Authors: Ward Bernadette M. , Anderson Karen S. , Sheldon Maria S.
Published: November 2005

Objective:  To describe and compare patterns of Home and Community Care (HACC) utilisation among culturally and linguistically diverse (CALD) people and Australian‐born residents of rural Victoria.

Design:  The HACC Minimum Data Set provides information regarding levels of service provision and coverage in Victoria. Data from January to June 2002 were analysed to provide a profile of client characteristics and service usage in rural Victoria. Patterns of service utilisation were compared with the profile of the CALD population in the 2001 Census.

Results:  The proportion of CALD residents who are HACC clients is consistent with demographic profiles. However, their extent of service usage is not consistent with patterns of use by Australian‐born residents. HACC clients born in non‐English‐speaking countries, receive 35% less hours of HACC service than their Australian‐born counterparts. HACC clients born overseas in English‐speaking countries receive nine per cent less hours of HACC service than the Australian‐born group (F = 8.9, P = 0.00). Both groups of overseas‐born clients use a smaller range of HACC services (F = 1.9, P = 0.16).

Conclusion:  Planners and service providers need to monitor levels of HACC service delivery among population groups to ensure that CALD population groups receive equitable levels of HACC services. The HACC Minimum Data Set is one source of data that can assist in this process.
Do health and medical workforce shortages explain the lower rate of rural consumers' complaints to Victoria's Health Services Commissioner?
Authors: Jones Judith A. , Humphreys John S. , Wilson Beth
Published: November 2005

Objective:  To identify which explanations account for lower rural rates of complaint about health services – (i) fear of consequences where there is little choice of alternative provider; (ii) a higher complaint threshold for rural consumers; (iii) lack of access to complaint mechanisms; or (iv) reduced access to services about which to complain.

Design:  Ecological study incorporating consumer complaint, population and workforce distribution data sources.

Setting:  All health care providers practising in Victoria.

Participants:  De‐identified records of all closed consumer complaints made to the Health Services Commissioner, Victoria, between March 1988 and April 2001 by Victorian residents (13 856 records).

Main outcome measures:  Differences in the percentage of under‐representation in complaint rates in total and for each of four categories of health services providers for different size communities.

Results:  No consistent relationship was observed between community size and either degree of under‐representation of complaints against any category of provider, or the proportion of serious or substantial complaints. Rural under‐representation was highest (41%) for dentists, the provider category with the lowest proportion working in rural areas (17%), and lowest (18%) for hospitals, with the highest representation in rural areas (28% of beds). More rural complaints were about access issues (10.7% rural and 8.4% metropolitan).

Conclusions:  Reduced opportunity to use health services due to rural health and medical workforce shortages was the best‐supported explanation for the lower rural complaint rate. Workforce shortages impact on the quality of rural health services and on residents’ opportunities to improve their health status.
Modelling of fatigue‐corrosion in Ti6246 alloy at 500°c
Authors: SARRAZIN‐BAUDOUX C.
Published: November 2005

This paper deals with a study of the influence of the atmospheric environment on the resistance against fatigue crack propagation of a Ti6246 titanium alloy at 500°C. Tests were performed in the near‐threshold and mid‐rate ranges under controlled gaseous environments, including vacuum and argon, with controlled partial pressures of water vapour and oxygen. A predominant detrimental influence of water vapour is demonstrated even under very low partial pressure, while oxygen gas is shown to moderate the influence of water vapour. A crack‐propagation model relating the growth rate to the effective stress intensity factor range is proposed to account for this competitive influence of water vapour and oxygen with respect to the test frequency.
Strain‐based multiaxial fatigue damage modelling
Authors: LIU Y. , MAHADEVAN S.
Published: November 2005

A new multiaxial fatigue damage model named characteristic plane approach is proposed in this paper, in which the strain components are used to correlate with the fatigue damage. The characteristic plane is defined as a material plane on which the complex three‐dimensional (3D) fatigue problem can be approximated using the plane strain components. Compared with most available critical plane‐based models for multiaxial fatigue problem, the physical basis of the characteristic plane does not rely on the observations of the fatigue crack in the proposed model. The cracking information is not required for multiaxial fatigue analysis, and the proposed model can automatically adapt for different failure modes, such as shear or tensile‐dominated failure. Mean stress effect is also included in the proposed model by a correction factor. The life predictions of the proposed fatigue damage model under constant amplitude loading are compared with a wide range of metal fatigue results in the literature.
Slow endogenous activity transients and developmental expression of K+–Cl− cotransporter 2 in the immature human cortex
Authors: Vanhatalo Sampsa , Palva J. Matias , Andersson Sture , Rivera Claudio , Voipio Juha , Kaila Kai
Published: November 2005

Spontaneous transients of correlated activity are a characteristic feature of immature brain structures, where they are thought to be crucial for the establishment of precise neuronal connectivity. Studies on experimental animals have shown that this kind of early activity in cortical structures is composed of long‐lasting, intermittent network events, which undergo a developmental decline that is closely paralleled by the maturation of GABAergic inhibition. In order to examine whether similar events occur in the immature human cortex, we performed direct current‐coupled electroencephalography (EEG) recordings from sleeping preterm babies. We show now that much of the preterm EEG activity is confined to spontaneous, slow activity transients. These transients are characterized by a large voltage deflection that nests prominent oscillatory activity in several frequency bands covering the whole frequency spectrum of the preterm EEG (<0.1–30 Hz). The slow voltage deflections had an amplitude of up to 800 µV. Most of these ‘giant’ events originated in the temporo‐occipital areas, with a maximum rate of about 8/min, and their occurrence as well as amplitude showed a decline by the time of normal birth. In age‐matched fetal brain tissue, this decrease in the spontaneous activity transients was associated with a developmental up‐regulation of the neuronal chloride extruder K+–Cl− cotransporter 2, a crucial molecule for the generation of inhibitory GABAergic Cl– currents. Our work indicates that slow endogenous activity transients in the immature human neocortex are mostly confined to the prenatal stage and appear to be terminated in parallel with the maturation of functional GABAergic inhibition.
Statistical properties of information processing in neuronal networks
Authors: Bonifazi Paolo , Ruaro Maria Elisabetta , Torre Vincent
Published: November 2005

Information processing and coding were analysed in dissociated hippocampal cultures, grown on multielectrode arrays. Multisite stimulation was used to activate different neurons and pathways of the network. The neural activity was binned into firing rates and the variability of the firing of individual neurons and of the whole population was analysed. In individual neurons, the timing of the first action potential (AP) was rather precise from trial to trial, whereas the timing of later APs was much more variable. Pooling APs in an ensemble of neurons reduced the variability of the response and allowed stimuli varying in intensity to be distinguished reliably in a single trial. A similar decrease of variability was observed pooling the first evoked APs in an ensemble of neurons. The size of the neuronal pool (∼ 50–100 neurons) and the time bin (∼ 20 ms) necessary to provide reproducible responses are remarkably similar to those obtained in in vivo preparations and in small nervous systems. Blockage of excitatory synaptic pathways mediated by NMDA receptors improved the mutual information between the evoked response and stimulus properties. When inhibitory GABAergic pathways were blocked by bicuculline the opposite effect was obtained. These results show how ensemble averages and an appropriate balance between inhibition and excitation allow neuronal networks to process information in a fast and reliable way.
Neuromagnetic correlates of visual motion coherence
Authors: Aspell J. E. , Tanskanen T. , Hurlbert A. C.
Published: November 2005

In order to characterize cortical responses to coherent motion we use magnetoencephalography (MEG) to measure human brain activity that is modulated by the degree of global coherence in a visual motion stimulus. Five subjects passively viewed two‐phase motion sequences of sparse random dot fields. In the first (incoherent) phase the dots moved in random directions; in the second (coherent) phase a variable percentage of dots moved uniformly in one direction while the others moved randomly. We show that: (i) visual‐motion‐evoked magnetic fields, measured with a whole‐scalp neuromagnetometer, reveal two transient events, within which we identify two significant peaks – the ‘ON‐M220’ peak approximately 220 ms after the onset of incoherent motion and the ‘TR‐M230’ peak, approximately 230 ms after the transition from incoherent to coherent motion; (ii) in lateral occipital channels, the TR‐M230 peak amplitude varies with the percentage of motion coherence; (iii) two main sources are active in response to the transition from incoherent to coherent motion, the human medial temporal area complex/V3 accessory area (hMT+/V3A) and the superior temporal sulcus (STS), and (iv) these distinct areas show a similar, significant dependence of response strength and latency on motion coherence.
Fine tuning of olfactory orientation behaviour by the interaction of oscillatory and single neuronal activity
Authors: Nikitin Evgeny S. , Zakharov Igor S. , Samarova Elena I. , Kemenes György , Balaban Pavel M.
Published: November 2005

We used a simple sensory and motor system to investigate the neuronal mechanisms of olfactory orientation behaviour. The main olfactory organs of terrestrial molluscs, the experimental animals used in this work, are located on the tips of their tentacles, which display complex movements when they explore a new environment. By reconstructing the trajectory of the tentacle tip (‘nose’) movements in three dimensions in freely moving snails, we showed that the protracted tentacles performed continuous scanning, both spontaneously and in response to odours. Odour applications elicited a brief startle‐like quiver of the tentacle in a concentration‐independent manner as well as a concentration‐dependent contraction. Previous work showed that activation of an identified cerebral motoneuron, MtC3, produces tentacle contraction. Here we showed that in semi‐intact preparations, MtC3 responded to odours in a concentration‐dependent manner, similar to the tentacle contraction response to the same odours in intact animals. This observation suggests that MtC3 is involved in the central control of the scanning area by regulating the tentacle length. Using voltage‐sensitive dyes and imaging, we demonstrated that during the hyperpolarizing phases of oscillations in the procerebral lobe, the main olfactory centre of the CNS of terrestrial molluscs, MtC3 spike frequency significantly decreased. We also showed that direct activation of the procerebral lobe resulted in the phasic inhibition of MtC3. This is therefore an example of an olfactory system in which the interaction of oscillatory and single neuronal activity plays an important role in the fine tuning of orientation behaviour to suit the particular odour environment.
A shift of visual spatial attention is selectively associated with human EEG alpha activity
Authors: Sauseng P. , Klimesch W. , Stadler W. , Schabus M. , Doppelmayr M. , Hanslmayr S. , Gruber W. R. , Birbaumer N.
Published: November 2005

Event‐related potentials and ongoing oscillatory electroencephalogram (EEG) activity were measured while subjects performed a cued visual spatial attention task. They were instructed to shift their attention to either the left or right visual hemifield according to a cue, which could be valid or invalid. Thereafter, a peripheral target had to be evaluated. At posterior parietal brain areas early components of the event‐related potential (P1 and N1) were higher when the cue had been valid compared with invalid. An anticipatory attention effect was found in EEG alpha magnitude at parieto‐occipital electrode sites. Starting 200 ms before target onset alpha amplitudes were significantly stronger suppressed at sites contralateral to the attended visual hemifield than ipsilateral to it. In addition, phase coupling between prefrontal and posterior parietal electrode sites was calculated. It was found that prefrontal cortex shows stronger phase coupling with posterior sites that are contralateral to the attended hemifield than ipsilateral sites. The results suggest that a shift of attention selectively modulates excitability of the contralateral posterior parietal cortex and that this posterior modulation of alpha activity is controlled by prefrontal regions.
Long‐term changes in blood–brain barrier permeability and white matter following prolonged systemic inflammation in early development in the rat
Authors: Stolp H. B. , Dziegielewska K. M. , Ek C. J. , Potter A. M. , Saunders N. R.
Published: November 2005

Epidemiological evidence in human fetuses links inflammation during development with white matter damage. Breakdown of the blood–brain barrier has been proposed as a possible mechanism. This was investigated in the present study by inducing a prolonged inflammatory response in newborn rats, with intraperitoneal injections of lipopolysaccharide (LPS; 0.2 mg/kg) given at postnatal (P) day 0, P2, P4, P6 and P8. An acute phase response was present over the whole period of injections. Changes in blood–brain barrier permeability were determined for small (sucrose and inulin) and large (protein) molecules. During and immediately after the inflammatory response, plasma proteins were detected in the brain only within white matter tracts, indicating an increased permeability of the blood–brain barrier to protein during this period. The alteration in permeability to protein was transient. In contrast, the permeability of the blood–brain barrier to 14C‐sucrose and 14C‐inulin was significantly higher in adult animals that had received serial LPS injections during development. Adult animals receiving a single 1 mg/kg LPS injection at P0 showed no alteration in blood–brain barrier permeability to either small or larger molecules. A significant decrease in the volume of CNPase immunoreactive presumptive white matter tracts occurred in the external capsule and corpus callosum at P9. These results demonstrate that a prolonged systemic inflammatory response in the early postnatal period in rats causes size selective increases in blood–brain barrier permeability at different stages of brain development and results in changes in white matter volume.
Scene perception: inferior temporal cortex neurons encode the positions of different objects in the scene
Authors: Aggelopoulos Nikolaos C. , Rolls Edmund T.
Published: November 2005

Inferior temporal cortex (IT) neurons have reduced receptive field sizes in complex natural scenes. This facilitates the read‐out of information about individual objects from IT, but raises the question of whether more than the single object present at the fovea is represented by the firing of IT neurons, as would be important for whole scene perception in which several objects may be located without eye movements. Recordings from IT neurons with five simultaneously presented objects, each subtending 7°, with one object at the fovea and the other four centred 10° eccentrically in the parafovea, showed that although 38 IT neurons had their best response to an effective stimulus at the fovea, eight IT neurons had their best response to an object when it was located in one or more of the parafoveal positions. Moreover, of 54 neurons tested for asymmetric parafoveal receptive fields, 35 (65%) had significantly different responses for different parafoveal positions. The asymmetry was partly related to competition within the receptive fields, as only 21% of the neurons had significant asymmetries when tested with just one object present located at the same parafoveal positions. The findings thus show that some evidence is conveyed by a population of IT neurons about the relative positions of several simultaneously presented objects in a scene extending well into the parafovea during a single fixation, and this is likely to be important in whole scene perception with multiple objects, including specifying the relative positions of different objects in a scene.
Aberrant trajectory of thalamocortical axons associated with abnormal localization of neurocan immunoreactivity in the cerebral neocortex of reeler mutant mice
Authors: Li Hong‐Peng , Oohira Atsuhiko , Ogawa Masaharu , Kawamura Koki , Kawano Hitoshi
Published: November 2005

We examined the molecular mechanisms underlying the formation of the thalamocortical pathway in the cerebral neocortex of normal and reeler mutant mice. During normal development of the mouse neocortex, thalamic axons immunoreactive for the neural cell adhesion molecule L1 rarely invaded the cortical plate and ran centered in the subplate which is immunoreactive for neurocan, a brain‐specific chondroitin sulfate proteoglycan. On the other hand, in homozygous reeler mutant mice, thalamic axons took an aberrant course to run obliquely through the cortical plate. Injection of bromodeoxyuridine at embryonic day 11 specifically labeled subplate neurons in normal mice, whilst in the reeler neocortex it labeled cells scattered in the cortical plate as well as in the superficial layer (superplate). Neurocan immunoreactivity was associated with the bromodeoxyuridine‐positive cells in the superplate, as well as being present in oblique bands within the cortical plate, along which L1‐bearing thalamic axons preferentially ran. The present results support our previous hypothesis proposed for normal rats that a heterophilic molecular interaction between L1 and neurocan is involved in determining the thalamocortical pathway within the neocortical anlage [T. Fukuda et al. (1997)Journal of Comparative Neurology, 382, 141–152].
Dysfunction of the cortico‐basal ganglia‐cortical loop in a rat model of early parkinsonism is reversed by metabotropic glutamate receptor 5 antagonism
Authors: Oueslati Abid , Breysse Nathalie , Amalric Marianne , Kerkerian‐Le Goff Lydia , Salin Pascal
Published: November 2005

This study examined the cellular correlates of the akinetic deficits produced in Wistar rats by discrete bilateral 6‐hydroxydopamine (6‐OHDA) striatal infusions in the dorsolateral striatum, mimicking the preferential denervation of the motor striatal territory in early symptomatic stage of Parkinson's disease (PD). Intraneuronal gene expression of cytochrome oxidase subunit I (COI), a metabolic index of neuronal activity, was increased in the subthalamic nucleus, substantia nigra pars reticulata and decreased in frontal cortical areas, but paradoxically unchanged in the striatum, globus pallidus, entopeduncular nucleus and ventrolateral thalamic nucleus. Neither preproenkephalin A nor preprotachykinin mRNA expression, markers of striatal projection neurons, were modified in the denervated striatal area despite 90% loss of dopamine (DA) terminals. Preproenkephalin A mRNA expression was however, decreased in the nondepleted striatal region, suggesting compensatory increase of dopamine tone from those spared areas. A chronic treatment with the metabotropic glutamate receptor 5 (mGluR5) antagonist 2‐methyl‐6‐(phenylethylnyl)‐pyridine (MPEP), which alleviated the akinetic disorders produced by the lesion, reversed the lesion‐induced variations of COI gene expression, moderately increased this marker in the structures unaffected by the lesion and did not modify the striatal neuropeptides gene expression. These data suggest that the expression of akinetic deficits in early parkinsonism is associated with focused metabolic changes in the cortico‐basal ganglia‐cortical loop downstream of the striatum and pallidal complex.
Cognitive flexibility and decision‐making in a model of conditional visuomotor associations
Authors: Loh Marco , Deco Gustavo
Published: November 2005

Arbitrary visuomotor associations map a stimulus onto a particular response upon reinforcing rewards. Changes in the associations between stimuli and responses require the neural networks to discard the already learned mappings and build new ones. This is a key aspect of cognitive flexibility. In addition, learning within this experimental paradigm requires a trial‐and‐error exploration strategy of the available stimulus–response associations. A system performing this task must be able to both build up mappings for stimulus–response associations and at the same time perform non‐deterministically to explore the behavioural space until it reaches certainty. We hypothesize an integrate‐and‐fire network model that accounts for the neurophysiological data of a conditional visuomotor association task and is able to show non‐deterministic behaviour. We aim at identifying multistable attractor regimes in the network dynamics, which intrinsically enable the system to make errors and thereby to perform trial‐and‐error exploration. Our model combines cognitive flexibility with multistable attractors in neurodynamical systems, believed to be the basis of decision‐making. If multistable attractors support the exploration of the behavioural space, then our model predicts that the brain should respond stochastically with correct or incorrect activity to visuomotor associations until it has reached certainty. This should be visible not only in the corresponding activity in the premotor area, but also in activity corresponding to other associations or even other stimuli in the prefrontal cortex.
Monitoring cerebral oxygenation in a pediatric patient undergoing surgery for vascular ring
Authors: JOSHI REENA K , MOTTA PABLO , HORIBE MAYUMI , MOSSAD EMAD
Published: November 2005

Regional cerebral oxygenation can be monitored using near‐infrared spectroscopy (NIRS). Inadequacy of collateral cerebral circulation and regional cerebral ischemia during cardiac and vascular surgery may be detected by the use of NIRS monitoring. We report a 2‐year‐old child who underwent surgical repair of vascular ring and subclavian reimplantation, where use of NIRS helped in early detection and timely intervention to prevent prolonged cerebral ischemia.
Thoracic epidural catheter in the management of a child with an anterior mediastinal mass: a case report and literature review
Authors: SOLIMAN LORAN M. , MOSSAD EMAD B.
Published: November 2005

We describe a case of an anterior mediastinal mass compressing the right main bronchus that required a biopsy through a thoracotomy incision. The anesthetic management of these patients is associated with several risks and challenges, including potential airway compression and cardiovascular collapse. Inhalation induction and maintenance of spontaneous respiration is recommended to preserve normal transpulmonary pressure gradient and improve flow through conducting airways. We placed a thoracic epidural catheter under general anesthesia as the main analgesic technique in order to maintain spontaneous breathing. The use of regional anesthesia, especially continuous epidurals in pediatric cardiothoracic anesthesia have many theoretical advantages including attenuation of the neuroendocrine response, facilitation of rapid extubation and improved ventilatory mechanics secondary to decreased narcotic requirements. The absolute risk of nerve injury and epidural hematoma for this procedure is unknown and hard to define in this patient population. We reviewed multiple studies and case reports addressing its safety and reported side effects. Finally, we emphasize that a thoracic epidural anesthesia is a reasonable choice that can be applied carefully in special situations even for children under general anesthesia.
Subcutaneous emphysema after dental treatment: a case report
Authors: TORGAY ADNAN , AYDIN ERDINC , CILASUN ULKEM , DURMAZ LALE , ARSLAN GULNAZ
Published: November 2005

Subcutaneous emphysema is the condition in which air or other gases penetrate the skin and submucosa causing soft‐tissue distention. This type of emphysema may be traumatic, iatrogenic or may occur spontaneously. This report describes the youngest case of subcutaneous emphysema related to dental treatment that has been documented to date. In addition to the patient's age, the case is of interest because subcutaneous emphysema is a rare complication of dental therapy.