bluuebunny/crossref_metadata_2025 huggingface dataset:
Achieving a balance in the current approach to the surgical treatment of hypoplastic left heart syndrome
Authors: Quintessenza James A. , Morell Victor O. , Jacobs Jeffrey P.
Published: September 2005

In this Supplement, and at its associated Symposium “Controversies of Hypoplastic Left Heart Syndrome”, various contributors presented a variety of topics regarding “state of the art” treatments for hypoplastic left heart syndrome. The extent of the differences within these various presentations attests to the very significant challenges that remain in optimizing care of these patients, and related ones with other types of functionally univentricular hearts. Of these challenges, the initial surgical approach, be it staged palliation or cardiac transplantation, has been a hotly debated issue, with diametrically opposed schools of thought.1Today, with further experience, technical advances, and dramatically improved outcomes, there seems to be an emerging complimentary role for both options, favoring a staged reconstructive approach in the majority of circumstances. We review here the salient issues that have lead to this position, and discuss strategies for maintaining a program offering both staged palliation and transplantation for patients with hypoplasia of the left heart.
Analysis and visualization of space science model output and data with CISM‐DX
Authors: Wiltberger M. , Weigel R. S. , Gehmeyr M. , Guild T.
Published: September 2005

Among the many challenges facing space physics today is the need for an analysis and visualization package which can examine the results from numerical and empirical models as well as observational data. In this paper we introduce the CISM‐DX package as a possible answer to this problem. We have created a tool which is capable of completing highly sophisticated visualizations of the results from a diverse set of models throughout the connected Sun‐Earth system. We begin with an overview of the open source software programs, OpenDX and Octave, which form the basis of our package. Next we discuss the extensions to these programs that we have added to enhance their utility to the space physics community. We also discuss the extensive database of observations that is included with CISM‐DX. Results from heliospheric simulations are used to highlight the ease at which a novice user can begin to utilize these tools. An energy budget calculation during a magnetospheric substorm simulation illustrates the more advanced analysis possible with the CISM‐DX package. Next we highlight the extensive database of observational measurements included with the distribution, along with tools for displaying them. This package is being released under an open source licensing agreement to facilitate and encourage community use and contribution.
Time constants of Earth's magnetotail for responding to a southward excursion of IMF: The super‐high‐pressure magnetotail event of 10 December 1996
Authors: Nakai H. , Kamide Y.
Published: September 2005

Geomagnetic and plasma conditions in the nightside magnetosphere and the northern polar region are examined in detail for the first 6 hours of 10 December 1996. In association with a southward turning of the interplanetary magnetic field, the polar cap potential drop began to increase and maximized within several minutes after the peak of the energy inflow from the solar wind into the magnetosphere. The total pressure observed by Geotail in the midmagnetotail, however, continued increasing for ∼50 min after the peak of the polar cap potential drop, resulting in an exceptionally high total pressure in the midmagnetotail. Auroral images from Polar and magnetograms from ground stations show that there was no major breakup of substorms during the period concerned. This unique event provides us with an opportunity to study the solar wind–magnetosphere coupling without any intense disturbances associated with major substorms. Using an equivalent circuit model, it is attempted to reproduce variations in the polar cap potential drop and the midtail total pressure. The time lag between them is particularly focused on in this study. It is found that the characteristic time constants of the equivalent circuit model for this event are significantly longer than those estimated in previous papers.
Extension of a Martian general circulation model to thermospheric altitudes: UV heating and photochemical models
Authors: González‐Galindo F. , López‐Valverde M. A. , Angelats i Coll M. , Forget F.
Published: September 2005

A fast method to incorporate the UV heating and the photochemistry of the neutral upper atmosphere of Mars into general circulation models (GCMs) is presented. On the basis of more detailed one‐dimensional (1‐D) models, the scheme we propose makes use of a division of the UV spectrum in 36 subintervals of 20 nm average width. Photoabsorption coefficients are computed allowing for overlapping and are tabulated as a function of suitable column abundances. The photochemistry proposed includes 12 compounds and uses the approximation of photochemical equilibrium for the three fastest species, OH, O(1D), and HO2. The behavior of the fast scheme is shown against detailed 1‐D calculations. The resulting acceleration is about a factor 200 in the UV heating, while in the photochemistry it is about a factor 100 at 120 km and much larger below. The proposed scheme has already been implemented into the GCM developed at the Laboratoire de Météorologie Dynamique‐CNRS in Paris (LMD), which therefore becomes the first single Martian GCM to cover the whole range of altitudes from the planet surface to the upper thermosphere. We present typical results of the Martian thermosphere obtained with the present scheme and the LMD‐GCM, in order to illustrate its behavior and stability. In particular, we show the sensitivity of the Martian upper atmosphere's thermal structure to the local photochemistry. Comparisons with previous models are also presented, as first steps in an ongoing validation study, necessarily extensive for this kind of GCM, which will include more detailed comparisons with recent and future data from space missions.
Increase in nitrate and chloride deposition in east Asia due to increased sulfate associated with the eruption of Miyakejima Volcano
Authors: Kajino Mizuo , Ueda Hiromasa , Satsumabayashi Hikaru , Han Zhiwei
Published: September 2005

The eruption of Miyakejima Volcano, 180 km south of Tokyo, Japan, since July 2000 has resulted in the emission of large amounts of sulfur dioxide. The volumes of sulfur dioxide emitted were vast, equivalent to half the anthropogenic emission from China on annual average. Short‐time aerosol sampling, conducted at the Happo Ridge observatory in the central mountainous region of Japan, has revealed that the abundant volcanic sulfate resulted in the expulsion of nonvolcanic nitrate and chloride in aerosols into the gas phase. As the deposition velocities of gaseous nitrate and chloride are much higher than those in aerosols, their deposition should be accelerated. This additional deposition is referred to as “indirect acidification” in this study, corresponding to “direct acidification” by the deposition of volcanic sulfate. This indirect acidification is estimated quantitatively using a regional‐scale Eulerian aerosol transport model and is found to be generally less pronounced than direct acidification, although the indirect effect was 2.1 greater than the direct effect over the North Pacific Ocean in winter. The minimum contribution of indirect acidification is found to be 7%, which is still not negligible. Indirect acidification may also occur in the case of general air pollution, accelerating the acid deposition of nitrate and chloride in sulfate‐rich contaminated air masses. It therefore appears to be important in general to consider indirect acidification in the discussion of environmental acidification by sulfur oxides.
Flow resistance and bed form geometry in a wide alluvial channel
Authors: Yang Shu‐Qing , Tan Soon‐Keat , Lim Siow‐Yong
Published: September 2005

This paper explores the underlying mechanism of flow resistance in a wide alluvial channel with bed forms. On the basis of published data, it is shown that the grain roughness can be taken as equal to 2 times the median diameter of the bed sediment. An empirical equation for the bed form roughness has been proposed, and it depends on the bed form height and bed form steepness. The influence of the bed form length and height on the total bed shear stress and energy slope is deliberated, and empirical expressions for the length of the separation zone behind the bed forms are also proposed. The study proposed an equation to compute the total bed shear stress as a function of the grain and bed form roughness as well as the important role of the bed form geometry in the overall flow resistance in alluvial channels. The model is tested and verified against 670 flume measurements and 1540 field observations. The computed and measured energy slopes are in good agreement with close to 71% of all data sets within the ±20% error band.
Atorvastatin Downregulates Tissue Plasminogen Activator-Aggravated Genes Mediating Coagulation and Vascular Permeability in Single Cerebral Endothelial Cells Captured by Laser Microdissection
Authors: Liu Xian Shuang , Zhang Zheng Gang , Zhang Li , Morris Daniel C , Kapke Alissa , Lu Mei , Chopp Michael
Published: September 2005

The effects of statins on gene expression of cerebral endothelial cells (ECs) in vivo have not been investigated after stroke. We developed a rapid double immunofluorescent staining protocol with antibodies against von Willebrand factor (a marker for endothelium) and glial fibrillary acidic protein (a marker for astrocytes) for laser capture microdissection to isolate single ECs in brain tissue of the rat. Using this protocol in combination with real-time PCR, we found that stroke significantly increased mRNA levels of protease-activated receptor 1 (PAR-1) and tissue factor (TF) in ECs isolated from ischemic cerebral microvessels compared with nonischemic vessels. Treatment of embolic stroke with recombinant human tissue plasminogen activator (rht-PA) 4 h after stroke further elevated PAR-1 mRNA levels nearly 1000-fold in the core and 500-fold in the boundary above the nonstroke group 30 h after stroke, while TF mRNA levels were elevated approximately 10 fold above the nonstroke group. Furthermore, stroke significantly increased matrix metalloproteinase (MMP) 2 and 9 mRNA levels in the ischemic core and boundary regions 6 and 30 h after stroke. Treatment with rht-PA-upregulated MMP2 expression in the ischemic boundary and core. Atorvastatin completely blocked rht-PA upregulation of the above genes, when atorvastatin in combination with rht-PA was administered 4 h after stroke. Monotherapy of atorvastatin 4 h after stroke did not significantly reduce expression of genes examined in the present study. These data provide evidence that atorvastatin reduces exogenous tPA-aggravated cerebral endothelial genes that mediate thrombosis and blood-brain barrier permeability, which could contribute to the beneficial effects of statins on thrombolytic treatment of acute stroke.
On the electron affinity of SiN and spectroscopic constants of SiN−
Authors: Kerkines Ioannis S. K. , Mavridis Aristides
Published: September 2005

Accurate spectroscopic constants and energetics were calculated for the two lowest-lying states of SiN and SiN− employing the coupled cluster methodology and very large basis sets (up to doubly augmented sextuple-ζ quality) accounting also for core∕valence correlation, one-electron Douglas-Kroll-Hess relativistic effects, and atomic spin-orbit couplings. Our best estimate for the adiabatic electron affinity of SiN is 3.002eV, in very good agreement with the recent, experimentally determined value of 2.949(8)eV. However, the calculated bond length of the SiN− XΣ+1 state at the same level, re=1.5904Å, is smaller than the indirectly extracted experimental value of 1.604(5)Å, pointing out that the latter value is either a bit overestimated or not as accurate as the ±0.005Å error bar indicates. For the neutral SiN, all calculated data are in excellent agreement with previous accurate experimental results.
Phase coexistence in a polydisperse charged hard-sphere fluid: Polymer mean spherical approximation
Authors: Kalyuzhnyi Yurij V. , Kahl Gerhard , Cummings Peter T.
Published: September 2005

We have reconsidered the phase behavior of a polydisperse mixture of charged hard spheres (CHSs) introducing the concept of minimal size neutral clusters. We thus take into account ionic association effects observed in charged systems close to the phase boundary where the properties of the system are dominated by the presence of neutral clusters while the amount of free ions or charged clusters is negligible. With this concept we clearly pass beyond the simple level of the mean spherical approximation (MSA) that we have presented in our recent study of a polydisperse mixture of CHS [Yu. V. Kalyuzhnyi, G. Kahl, and P. T. Cummings, J. Chem. Phys. 120, 10133 (2004)]. Restricting ourselves to a 1:1 and possibly size-asymmetric model we treat the resulting polydisperse mixture of neutral, polar dimers within the framework of the polymer MSA, i.e., a concept that—similar as the MSA—readily can be generalized from the case of a mixture with a finite number of components to the polydisperse case: again, the model belongs to the class of truncatable free-energy models so that we can map the formally infinitely many coexistence equations onto a finite set of coupled, nonlinear equations in the generalized moments of the distribution function that characterizes the system. This allows us to determine the full phase diagram (in terms of binodals as well as cloud and shadow curves), we can study fractionation effects on the level of the distribution functions of the coexisting daughter phases, and we propose estimates on how the location of the critical point might vary in a polydisperse mixture with an increasing size asymmetry and polydispersity.
Calculation of spin-densities within the context of density functional theory. The crucial role of the correlation functional
Authors: Filatov Michael , Cremer Dieter
Published: September 2005

It is demonstrated that the LYP correlation functional is not suited to be used for the calculation of electron spin resonance hyperfine structure (HFS) constants, nuclear magnetic resonance spin-spin coupling constants, magnetic, shieldings and other properties that require a balanced account of opposite- and equal-spin correlation, especially in the core region. In the case of the HFS constants of alkali atoms, LYP exaggerates opposite-spin correlation effects thus invoking too strong in-out correlation effects, an exaggerated spin-polarization pattern in the core shells of the atoms, and, consequently, too large HFS constants. Any correlation functional that provides a balanced account of opposite- and equal-spin correlation leads to improved HFS constants, which is proven by comparing results obtained with the LYP and the PW91 correlation functional. It is suggested that specific response properties are calculated with the PW91 rather than the LYP correlation functional.
Interface structure and phase of epitaxial SrTiO3 (110) thin films grown directly on silicon
Authors: Hao J. H. , Gao J. , Wang Z. , Yu D. P.
Published: September 2005

The interface structure and phase between SrTiO3 (110) on Si (100) have been investigated using high-resolution transmission electron microscopy and x-ray photoelectron spectroscopy. The SrTiO3∕Si interface was found to be epitaxially crystallized without any amorphous oxide layer. The formation of Sr silicate at the interface was suggested by considering the fact of the core-level spectra of the Si 2p, O 1s, and Sr 3d. Our results suggest that the presence of a coincident site lattice at the interface between Si and a Sr silicate and/or SrTiO3 may help to stabilize SrTiO3 in the epitaxial orientation reported in the work.
Volatile fractionation in the early solar system and chondrule/matrix complementarity
Authors: Bland Philip A. , Alard Olivier , Benedix Gretchen K. , Kearsley Anton T. , Menzies Olwyn N. , Watt Lauren E. , Rogers Nick W.
Published: September 2005

Bulk chondritic meteorites and terrestrial planets show a monotonic depletion in moderately volatile and volatile elements relative to the Sun's photosphere and CI carbonaceous chondrites. Although volatile depletion was the most fundamental chemical process affecting the inner solar nebula, debate continues as to its cause. Carbonaceous chondrites are the most primitive rocks available to us, and fine-grained, volatile-rich matrix is the most primitive component in these rocks. Several volatile depletion models posit a pristine matrix, with uniform CI-like chemistry across the different chondrite groups. To understand the nature of volatile fractionation, we studied minor and trace element abundances in fine-grained matrices of a variety of carbonaceous chondrites. We find that matrix trace element abundances are characteristic for a given chondrite group; they are depleted relative to CI chondrites, but are enriched relative to bulk compositions of their parent meteorites, particularly in volatile siderophile and chalcophile elements. This enrichment produces a highly nonmonotonic trace element pattern that requires a complementary depletion in chondrule compositions to achieve a monotonic bulk. We infer that carbonaceous chondrite matrices are not pristine: they formed from a material reservoir that was already depleted in volatile and moderately volatile elements. Additional thermal processing occurred during chondrule formation, with exchange of volatile siderophile and chalcophile elements between chondrules and matrix. This chemical complementarity shows that these chondritic components formed in the same nebula region.
Why Illness Causes More Serious Economic Damage than Crop Failure in Rural Cambodia
Authors: Kenjiro Yagura
Published: September 2005

In rural Cambodia, illness has caused more serious economic damage to rural households than crop failure. This article explores the reasons for this using data on the strategies adopted by households in two Cambodian villages to cope with these different types of shock. The data show that Cambodian households can cope with crop failure by earning additional income. However, to cope with illness, which entails lump‐sum treatment costs, they have to borrow money or sell their assets, because households cannot acquire the necessary funds in a short period just by earning additional income. Combined with the harsh conditions of credit markets (high interest rates, strict debt collection and credit rationing), and weak risk‐sharing among households, this results in illness causing a large number of land sales in the surveyed villages.
Temporal and spatial patterns in the emigrations of the army ant Dorylus (Anomma) molestus in the montane forest of Mt Kenya
Authors: Schöning Caspar , Njagi Washington M. , Franks Nigel R.
Published: September 2005

Abstract.  1. The emigration behaviour of the army ant Dorylus (Anomma) molestus was studied in the montane forest of Mt Kenya. This species forages by massive swarm raids (mean width 10.3 m ± 4.6 m SD), which are assumed to have a strong negative impact on the densities of prey populations.

2. For non‐reproductive colonies the stay duration in a nest is highly variable (median 17, range 3–111 days). This suggests that the frequency of emigrations is not dictated by a brood cycle as an underlying endogenous pattern generator.

3. Colony density is high (mean nearest neighbour's distance 82.1 m ± 29.4 m SD) and mean foraging range is 75.0 m, so encounters with neighbouring colonies occur frequently.

4. The straight line emigration distance is on average 92.7 m (± 29.7 SD). The emigration direction is random with respect to absolute bearing and also relative to the direction of the previous emigration. However, the emigration direction is influenced by the location of the nearest neighbour. Colonies typically emigrate directly away from their nearest neighbour.

5. Local food depletion is likely to be the ultimate cause for emigrations in this species, because emigration distance is larger than foraging range and colonies move away from their nearest neighbour. A small percentage of emigrations may be triggered by pangolin attacks on nests.

6. Contrary to the prediction of a recently developed mathematical model for epigaeic swarm‐raiding Dorylus (Anomma) species, D. (A.) molestus colonies do not engage in intraspecific battles. Possible reasons for the absence of fights between colonies despite apparently fierce intraspecific competition are discussed.
Potential sexual transmission of environmental microbes in a traumatically inseminating insect
Authors: Reinhardt Klaus , Naylor Richard A. , Siva‐Jothy Michael T.
Published: September 2005

Abstract.  1. Very little attention has been paid to the importance of environmental microbes and how they gain access to potential hosts during host wounding or sexual interactions. Male members of the family Cimicidae (including the haematophagous human pest, the bed bug, Cimex lectularius) show traumatic insemination: in order to transfer sperm the male punctures the female's cuticle using a needle‐like intromittent organ. The microbes from the local environment that gain entry into females during mating have previously been shown to be an important source of mortality. This study aimed to identify these microbes and their natural environmental substrates.

2. Nine different microbe taxa from the surface of the cuticle were identified, five of them (two Penicillium spp., Stenotrophomonas, Enterobacter, Bacillus) were found in the local environment as well as on the intromittent organ of male bed bugs: these are strong candidates for the causal agents of mating‐induced female mortality. Local differences in the microbial communities and their hosts' response to them are discussed as a source of reproductive isolation.

3. Four microbe genera (Scopulariopsis, Staphylococcus, Arthrobacter, Micrococcus) were found exclusively on blood agar. One of them, and four grown on regular agar, are classified as human pathogens. However, because no microbes were isolated from the piercing and sucking mouthparts the epidemiological significance of bed bugs carrying externally attached microbes is probably low.
Contextual Influences on Marriage
Authors: Karney Benjamin R. , Bradbury Thomas N.
Published: September 2005

Current proposals to promote and strengthen marriage among low-income populations focus on values and behavioral skills as primary targets of intervention. Marital research that examines contextual influences on marriage calls these emphases into question. Ethnographic and survey research reveal no evidence that populations experiencing higher rates of divorce value healthy marriages any less than other populations do. Longitudinal and observational research reveals two mechanisms through which the environment of a marriage may enhance or constrain effective relationship maintenance. First, some environments contain fewer sources of support and pose more severe challenges than others, presenting marriages in those environments with greater burdens than marriages in more supportive environments are faced with. Second, when demands external to the marriage are relatively high, even couples with adequate coping skills may have difficulty exercising those skills effectively. Together, such findings suggest that successful policies and interventions to strengthen marriages need to acknowledge the environments within which marriages take place.
The Neural Bases of Placebo Effects in Pain
Authors: Wager Tor D.
Published: September 2005

Placebo effects are beneficial effects of treatment caused not by the biological action of the treatment but by one's response to the treatment process itself. One possible mechanism of placebo treatments is that they create positive expectations, which change one's appraisal of the situation and may thereby shape sensory and emotional processing. Recent brain-imaging evidence suggests that placebo-induced expectations of analgesia increase activity in the prefrontal cortex in anticipation of pain and decrease the brain's response to painful stimulation. These findings suggest that placebo treatments can alter experience, not just alter what participants are willing to report about pain. To the extent that they involve neural systems mediating expectancy and appraisal, placebo effects in pain may share common circuitry with placebo effects in depression, Parkinson's disease, and other disorders.
Understanding the Point of Chimpanzee Pointing
Authors: Leavens David A. , Hopkins William D. , Bard Kim A.
Published: September 2005

Pointing has long been considered to be a uniquely human, universal, and biologically based gesture. However, pointing emerges spontaneously, without explicit training, in captive chimpanzees. Because pointing is commonplace in captive chimpanzees and virtually absent in wild chimpanzees, and because both captive and wild chimpanzees are sampled from the same gene pool, pointing by captive apes is attributable to environmental influences on communicative development. If pointing by captive chimpanzees is so variably expressed in different rearing environments, this suggests that pointing by humans may also be attributable to situational factors that make pointing effective in certain developmental contexts.
The evolution of immune‐related genes from disease carrying mosquitoes: diversity in a peptidoglycan‐ and a thioester‐recognizing protein
Authors: Little T. J. , Cobbe N.
Published: September 2005

Adaptive polymorphism may be common in immune system genes as co‐evolutionary interactions foster diversity; either through ongoing positive selection (arms races), or balancing selection. DNA sequence diversity in two putative immune system genes was examined in species of the genus Anopheles and from Aedes aegypti. For one gene, encoding the peptidoglycan recognizing protein PGRPLB, there was evidence of purifying selection, suggesting that selection acts to eliminate sequence variation. For another gene, encoding the thioester‐containing protein TEP3, higher levels of amino acid replacement were found than would be expected under neutral models of evolution – an indication that this gene has been subject to repeated bouts of positive selection.
Assessing the odd secondary structural properties of nuclear small subunit ribosomal RNA sequences (18S) of the twisted‐wing parasites (Insecta: Strepsiptera)
Authors: Gillespie J. J. , McKenna C. H. , Yoder M. J. , Gutell R. R. , Johnston J. S. , Kathirithamby J. , Cognato A. I.
Published: September 2005

We report the entire sequence (2864 nts) and secondary structure of the nuclear small subunit ribosomal RNA (SSU rRNA) gene (18S) from the twisted‐wing parasiteCaenocholax fenyesi texensisKathirithamby & Johnston (Strepsiptera: Myrmecolacidae). The majority of the base pairings in this structural model map on to the SSU rRNA secondary and tertiary helices that were previously predicted with comparative analysis. These regions of the core rRNA were unambiguously aligned across all Arthropoda. In contrast, many of the variable regions, as previously characterized in other insect taxa, had very large insertions inC. f. texensis. The helical base pairs in these regions were predicted with a comparative analysis of a multiple sequence alignment (that containsC. f. texensisand 174 published arthropod 18S rRNA sequences, including eleven strepsipterans) and thermodynamic‐based algorithms. Analysis of our structural alignment revealed four unusual insertions in the core rRNA structure that are unique to animal 18S rRNA and in general agreement with previously proposed insertion sites for strepsipterans. One curious result is the presence of a large insertion within a hairpin loop of a highly conserved pseudoknot helix in variable region 4. Despite the extraordinary variability in sequence length and composition, this insertion contains the conserved sequences 5′‐AUUGGCUUAAA‐3′ and 5′‐GAC‐3′ that immediately flank a putative helix at the 5′‐ and 3′‐ends, respectively. The longer sequence has the potential to form a nine base pair helix with a sequence in the variable region 2, consistent with a recent study proposing this tertiary interaction. Our analysis of a larger set of arthropod 18S rRNA sequences has revealed possible errors in some of the previously published strepsipteran 18S rRNA sequences. Thus we find no support for the previously recovered heterogeneity in the 18S molecules of strepsipterans. Our findings lend insight to the evolution of RNA structure and function and the impact large insertions pose on genome size. We also provide a novel alignment template that will improve the phylogenetic placement of the Strepsiptera among other insect taxa.
Radiation‐induced changes in gene expression in the silkworm revealed by serial analysis of gene expression (SAGE)
Authors: Huang J. , Miao X. , Jin W. , Couble P. , Zhang Y. , Liu W. , Shen Y. , Zhao G. , Huang Y.
Published: September 2005

Serial analysis of gene expression (SAGE) was used to examine the profile of expressed genes during embryonic development in the domesticated silkworm, Bombyx mori, after irradiation with Cobalt‐60. A comparison of the SAGE sequence tags derived from irradiated embryos with those from normal embryos revealed 673 differentially expressed genes (P < 0.01 and at least three folds change). Of these, 292 genes were highly expressed in normal embryos and 381 genes were highly expressed in irradiated embryos. These results provide valuable information for understanding the mechanisms of radiation‐induced changes in gene expression. In addition, it was noted that the generation of longer cDNA fragments from SAGE tags is an efficient way to identify genes, thereby facilitating the analysis of large numbers of unknown genes.
The pathogen Neisseria meningitidis requires oxygen, but supplements growth by denitrification. Nitrite, nitric oxide and oxygen control respiratory flux at genetic and metabolic levels
Authors: Rock Jonathan D. , Mahnane M. Reda , Anjum Muna F. , Shaw Jonathan G. , Read Robert C. , Moir James W. B.
Published: September 2005

The human pathogen Neisseria meningitidis is the major causative agent of bacterial meningitis. The organism is usually treated as a strict aerobe and is cultured under fully aerobic conditions in the laboratory. We demonstrate here that although N. meningitidis fails to grow under strictly anaerobic conditions, under oxygen limitation the bacterium expresses a denitrification pathway (reduction of nitrite to nitrous oxide via nitric oxide) and that this pathway supplements growth. The expression of the gene aniA, which encodes nitrite reductase, is regulated by oxygen depletion and nitrite availability via transcriptional regulator FNR and two‐component sensor‐regulator NarQ/NarP respectively. Completion of the two‐step denitrification pathway requires nitric oxide (NO) reduction, which proceeds after NO has accumulated during batch growth under oxygen‐limited conditions. During periods of NO accumulation both nitrite and NO reduction are observed aerobically, indicating N. meningitidis can act as an aerobic denitrifier. However, under steady‐state conditions in which NO is maintained at a low concentration, oxygen respiration is favoured over denitrification. NO inhibits oxidase activity in N. meningitidis with an apparent Ki NO = 380 nM measured in intact cells. The high respiratory flux to nitrite after microaerobic growth and the finding that accumulation of the denitrification intermediate NO inhibits oxygen respiration support the view that denitrification is a pathway of major importance in N. meningitidis.
Phosphate limitation induces catalase expression inSinorhizobium meliloti,Pseudomonas aeruginosaandAgrobacterium tumefaciens
Authors: Yuan Ze‐Chun , Zaheer Rahat , Finan Turlough M.
Published: September 2005

Growth ofSinorhizobium melilotiunder Pi‐limiting conditions induced expression of the major H2O2‐inducible catalase (HPII) gene (katA) in this organism. This transcription required the PhoB transcriptional regulator and initiated from a promoter that was distinct from the OxyR‐dependent promoter which activateskatAtranscription in response to addition of H2O2. In N2‐fixing root nodules,katAwas transcribed from the OxyR‐ and not the PhoB‐dependent promoter. This is consistent with the accumulation of reactive oxygen species (ROS) in nodules and also indicates that bacteroids within nodules are not Pi‐limited. Pi‐limited growth also induced expression of catalase genes inAgrobacterium tumefaciens(HPI) andPseudomonas aeruginosa(PA4236‐HPI) suggesting that this may be a widespread phenomenon. The response is not a general stress response as in bothS. melilotiandP. aeruginosaincreased transcription is mediated by the phosphate responsive transcriptional activator PhoB. The phenotypic consequences of this response were demonstrated inS. melilotiby the dramatic increase in H2O2resistance of wild type but notphoBmutant cells upon growth in Pi‐limiting media. Our data indicate that inS. meliloti,katAand other genes whose products are involved in protection from oxidative stress are induced upon Pi‐limitation. These observations suggest that as part of the response to Pi‐limitation,S.meliloti,P. aeruginosaandA. tumefacienshave evolved a capacity to increase their resistance to oxidative stress. Whether this capacity evolved because Pi‐starved cells generate more ROS or whether the physiological changes that occur in the cells in response to Pi‐starvation render them more sensitive to ROS remains to be established.
Characterization of EBV‐transformed B‐cells Established from an Individual Homozygously Mutated (G329A) in the FUT7α1,3‐fucosyltransferase Gene
Authors: Bengtson P. , Zetterberg H. , Mellberg T. , Påhlsson P. , Larson G.
Published: September 2005

The α1,3‐fucosyltransferase VII (Fuc‐TVII) is involved in the biosynthesis of E‐ and P‐selectin ligands such as sialyl Lewis x (SLex) on human leukocytes. Recently, individuals were characterized carrying a missense mutation (G329A; Arg110‐Gln) in the FUT7 gene encoding this enzyme. The mutated FUT7 construct produced a Fuc‐TVII enzyme with impaired activity compared with the wildtype enzyme. Polymorphonuclear granulocytes from an individual carrying this mutation homozygously also showed a reduced expression of SLex. In the present study, we have established Epstein–Barr virus‐transformed B‐cell lines from this individual (SIGN) and from an individual not carrying the mutation (IWO). The cell lines were confirmed to be of B‐cell origin by flow cytometry analysis. IWO cells interacted with E‐selectin in an in vitro flow chamber analysis whereas SIGN cell did not. However, when SIGN cell was transiently transfected with wildtype FUT7 cDNA, interaction with E‐selectin could be restored. Cell surface expression of the SLex‐related epitopes recognized by antibodies CSLEX‐1, KM‐93 and HECA‐452 was elevated on IWO cells compared with that on SIGN cells, consistent with a role of these antigens in E‐selectin recognition. These cell lines will be useful in further characterization of E‐selectin ligands and encourage further studies on the consequences of the FUT7‐G329A mutation in vivo.
Adenovirus Transduction and Culture Conditions Affect the Immunogenicity of Murine Dendritic Cells
Authors: Salucci V. , Lena A. M. , Ciliberto G. , Scarselli E. , La Monica N.
Published: September 2005

Adenovirus vectors encoding carcinoembryonic antigen (Ad‐CEA) or costimulatory molecules CD80, intercellular adhesion molecule‐1 (ICAM‐1) and leucocyte function‐associated antigen‐3 (LFA‐3) (Ad‐STIM) were used to transduce murine bone marrow‐derived dendritic cells (BMDC). BMDC were characterized for expression of activation markers and for their ability to elicit protective immunity against MC38‐CEA tumours in wildtype and CEA‐transgenic (CEA‐tg) mice. To determine optimal culture conditions, studies were conducted using BMDC cultured in heterologous bovine serum or autologous mouse serum. Transduction of cells grown in presence of heterologous serum increased the expression of costimulatory molecules, major histocompatibility complex class II, of IL‐6 and IL‐12. Upon vaccination, tumour protection was not specific and was observed also with untransduced cells. Transduced BMDC cultured in the presence of autologous serum showed low expression of the activation markers, did not express IL‐6 and had reduced ability to stimulate T‐cell proliferation. Nonetheless, CEA‐specific CD8+ T‐cell response was enhanced upon coinfection of Ad‐STIM and Ad‐CEA in both mouse strains, although this immune response was not sufficient to protect CEA‐tg mice from tumour challenge. These studies support the use of BMDC transduced with Ad vectors encoding tumour antigens for cancer immunotherapy and demonstrate that culture conditions greatly affect the immunological properties of these cells.
Chagasic Patients with Indeterminate Clinical Form of the Disease have High Frequencies of Circulating CD3+CD16–CD56+ Natural Killer T Cells and CD4+CD25High Regulatory T Lymphocytes
Authors: Vitelli‐Avelar D. M. , Sathler‐Avelar R. , Dias J. C. P. , Pascoal V. P. M. , Teixeira‐Carvalho A. , Lage P. S. , Elói‐Santos S. M. , Corrêa‐Oliveira R. , Martins‐Filho O. A.
Published: September 2005

Several studies have demonstrated that different clinical manifestations of human Chagas' disease are associated with distinct and complex host–parasite relationships directly involving the immune system. In this context, it has been proposed that tissue damage might be more severe in the absence of regulatory mechanisms that involve both innate and adaptive immune responses. Herein, we describe a descriptive phenotypic profile focusing on the frequency of major regulatory T cells [CD4+CD25high and natural killer T (NKT) lymphocytes] in different clinical forms of Chagas' disease. Ex vivo immunophenotyping of whole blood demonstrated that the indeterminate clinical form displays a higher frequency of both CD4+CD25high and NKT regulatory cells (CD3+CD16–CD56+), associated with increased levels of circulating cytotoxic NK cells (CD3–CD16+CD56+ and CD3–CD16+CD56dim NK cells). By contrast, the increased percentage of activated CD8+HLA‐DR+ T‐cell subset was exclusively associated with severe clinical forms of Chagas' disease. We hypothesize that regulatory T cells may be able to control the deleterious cytotoxic activity in the indeterminate clinical form by inhibiting the activation of CD8+HLA‐DR+ T cells. The lack of regulated populations in cardiac and digestive clinical forms could account for impaired immune response that culminates in strong cytotoxic activity and tissue damage.
Nickel Elicits Concomitant and Correlated in vitro Production of Th1‐, Th2‐Type and Regulatory Cytokines in Subjects with Contact Allergy to Nickel
Authors: Minang J. T. , Troye‐Blomberg M. , Lundeberg L. , Ahlborg N.
Published: September 2005

Nickel (Ni2+) elicits production of functionally distinct cytokines in vitro, but the relation between the cytokine profile and the degree of the allergic reaction in vivo needs to be better defined in order to improve the understanding of the immunological mechanisms involved in contact allergy and to facilitate development of in vitro diagnostics. The aim of the study was to define Th1‐type [interferon‐γ (IFN‐γ)], Th2‐type [interleukin‐4 (IL‐4), IL‐5 and IL‐13] and regulatory (IL‐10) cytokine responses to Ni2+ in peripheral blood mononuclear cells (PBMC) from subjects with varying patch test reactivity to Ni2+. The study included subjects with strong (+3), moderate (+2), weak (+1) or negative (controls) patch test reactivity to Ni2+ (n = 10 per group). All +3 and +2 subjects but only three +1 subjects had a clinical history of contact allergy to Ni2+. Cytokine production of PBMC stimulated with Ni2+ was determined by enzyme‐linked immunospot and/or enzyme‐linked immunosorbent assay. Ni2+ elicited significant production of all cytokines in PBMC from patch‐test‐positive subjects versus controls with a positive correlation between each cytokine and the patch test reactivity as well as with other cytokines. More subjects responded to Ni2+ above cut‐off values with Th2‐type cytokines as compared with IFN‐γ or IL‐10; 100% of +3, 80% of +2, 50% of +1 and 0% of control subjects displayed reactivity to Ni2+ based on IL‐4 and IL‐13 assays. Despite the prevailing view of Ni2+ allergy as a type‐1‐mediated condition, the in vivo reactivity to Ni2+ correlated with a mixed Th1‐type, Th2‐type and regulatory cytokine response to Ni2+in vitro. The results accentuate the importance of type 2 responses in contact allergy and also demonstrate that IL‐4 and IL‐13 are reliable markers for Ni2+ allergy.
The development and progression of allergy to multiple nuts at different ages
Authors: Clark Andrew T. , Ewan Pamela W.
Published: September 2005

The aims of this study were to define the development of sensitization and clinical allergy to multiple nut types by age, and to identify associations. This observational cross‐ sectional study was carried out in a tertiary level allergy clinic. Seven hundred and eighty four nut‐allergic children, prospectively enrolled on first attendance with history of a type‐1 allergic reaction shortly after definite nut ingestion with evidence of sensitization (presence of nut‐specific IgE) by skin prick test (SPT) to peanut, Brazil, almond, hazel and walnut (positive ≥ 3 mm). Details of exposure (tolerance or allergy) to each nut were obtained. The main outcome measures were mono or multisensitization (specific IgE to one or more than one nut type, demonstrated by SPT); mono or multiallergy (clinical allergy to one or more than one nut type). By 2 yr of age at least 19% were multisensitized, and 2% multiallergic. Increasing proportions were exposed to multiple nut types with increasing age (23% at 2 yr to 73% by 10 yr) and greater proportions were multisensitized (19% at 2 yr to 86% at 5–14 yr) and multiallergic (2% at 2 yr to 47% at 14 yr). This study is the first to define the natural history of multiple nut allergies in childhood. New findings are that a large proportion of those aged 0–1 yr with nut allergy are already sensitized (have specific IgE) to multiple nut types, implying in utero or early life sensitization; those who present later in childhood are increasingly likely to be sensitized and clinically allergic to multiple nuts. This is related to increased duration of allergy and exposure to multiple nut types with age. Children with nut allergy should avoid all nut types from the onset.
Characteristics of asthma and airway hyper‐responsiveness after premature birth
Authors: Halvorsen Thomas , Skadberg Britt Torunn , Eide Geir Egil , Røksund Ola , Aksnes Lage , Øymar Knut
Published: September 2005

Asthma‐like symptoms and airway hyper‐responsiveness (AHR) are frequently reported in children subsequent to premature birth and bronchopulmonary dysplasia (BPD). There is limited knowledge on the mechanisms underlying these respiratory manifestations. Generally, childhood asthma and AHR is described within a context of inheritance, allergy and eosinophilic airway inflammation, and often in relation to cigarette exposures. We investigated these factors in relation to current asthma and AHR in a population‐based cohort of 81 young people, born with gestational age ≤28 wk or birth weight ≤1000 g, and in a matched term‐born control population. In the pre‐term population, asthma and AHR were additionally studied in relation to neonatal respiratory morbidity. At follow up, more pre‐term than control subjects had asthma. Forced expiratory volume in first second (FEV1) was reduced, AHR was substantially increased, and the level of the urinary leukotriene metabolite E4 (U‐LTE4) was increased in the pre‐term population compared to the term‐born. In control subjects, asthma and AHR was associated with a pattern consistent with inheritance, allergy, airway inflammation, and cigarette exposures. In the pre‐terms, asthma and AHR was either unrelated or less related to these factors. Instead, AHR was strongly related to a neonatal history of BPD and prolonged requirement for oxygen treatment. In conclusion, asthma and AHR subsequent to extremely premature birth differed from typical childhood asthma with respect to important features, and AHR was best explained by neonatal variables. These respiratory manifestations thus seem to represent a separate clinical entity.
Ultrastructural findings in feline corneal sequestra
Authors: Cullen Cheryl L. , Wadowska Dorota W. , Singh Amreek , Melekhovets Yuri
Published: September 2005

Objectives (1) To describe the ultrastructural features of corneal sequestra in cats; and (2) to enhance our understanding regarding the pathogenesis of feline corneal sequestration.

Methods Nine corneal sequestra were harvested via keratectomy from globes of nine cats. The sequestra were routinely fixed then postfixed for high resolution light and transmission electron microscopy (HR‐LM and TEM, respectively). The tissues were embedded in Epon/Araldite. Sections of 0.5‐µm thickness were cut and stained with 1% toluidine blue in 1% sodium tetraborate solution for HR‐LM. Ultrathin sections were collected on copper grids and stained with uranyl acetate and Sato's lead stain for TEM. Ultrathin sections were examined and the images were captured on an Advantage HR CCD camera using a Hitachi 7500 electron microscope operated at 80 kV. Two healthy corneas from two cats were harvested immediately following euthanasia. These corneal tissues (control samples) were processed in the same manner as the corneal sequestra for HR‐LM and TEM. A portion of each sequestrum was also submitted for polymerase chain reaction (PCR) testing for infectious agents including feline herpesvirus‐1 (FHV‐1),Toxoplasma gondii,Chlamydophila felisandMycoplasmaspp.

Results Ultrastructure of healthy corneal tissues revealed basal corneal epithelial cells aligned adjacent to a thin acellular layer similar to Bowman's layer with underlying tightly packed, regularly arranged, collagen fibrils oriented in different planes. Keratocytes were elongated and had long and irregularly shaped nuclei, and cytoplasm contained rough endoplasmic reticulum and abundant membrane‐bound vesicles. In contrast, corneal sequestra contained varying amounts of an amorphous, electron‐dense substance, continuous with intact basal epithelial basement membranes peripherally, and overlying corneal ulceration and loosely packed collagen fibrils. Remnants of necrotic keratocytes were seen in spaces between disarranged collagen layers. In all samples, occasional keratocytes exhibited morphology indicative of apoptosis including clumping and margination of chromatin, and shrunken cytoplasm. Varying degrees of inflammation were noted on HR‐LM and TEM of affected corneas including peri‐ and intralesional neutrophils, lymphocytes, plasma cells, and macrophages. Corneal sequestra were FHV‐1‐positive (n = 3), FHV‐1‐ andT. gondii‐positive (n = 1),T. gondii‐positive (n = 3), or negative for DNA of these infectious agents (n = 2) using PCR. All corneal sequestra were negative for DNA ofChlamydophila felisandMycoplasmaspp. using PCR.

Conclusions Apoptosis may play a role in the pathogenesis of feline corneal sequestration independent of the presence of DNA of these infectious organisms. Prospective clinical studies are warranted to further understand the significance ofT. gondiiin relation to feline corneal sequestration.