Accumulation of human heat shock protein 60-reactive T cells in the gingival tissues of periodontitis patients

Heat shock protein 60s (hsp60) are remarkably immunogenic, and both T-cell and antibody responses to hsp60 have been reported in various inflammatory conditions. To clarify the role of hsp60 in T-cell responses in periodontitis, we examined the proliferative response of peripheral blood mononuclear cells (PBMC), as well as the cytokine profile and T-cell clonality, for periodontitis patients and controls following stimulation with recombinant human hsp60 and Porphyromonas gingivalis GroEL. To confirm the infiltration of hsp60-reactive T-cell clones into periodontitis lesions, nucleotide sequences within complementarity-determining region 3 of the T-cell receptor (TCR) beta-chain were compared between hsp60-reactive peripheral blood T cells and periodontitis lesion-infiltrating T cells. Periodontitis patients demonstrated significantly higher proliferative responses of PBMC to human hsp60, but not to P. gingivalis GroEL, than control subjects. The response was inhibited by anti-major histocompatibility complex class 11 antibodies. Analysis of the nucleotide sequences of the TCR demonstrated that human hsp60-reactive T-cell clones and periodontitis lesion-infiltrating T cells have the same receptors, suggesting that hsp60-reactive T cells accumulate in periodontitis lesions. Analysis of the cytokine profile demonstrated that hsp60-reactive PBMC produced significant levels of gamma interferon (IFN-gamma) in periodontitis patients, whereas P. gingivalis GroEL did not induce any, skewing toward a type1 or type2 cytokine profile. In control subjects no significant expression of IFN-gamma or interleukin 4 was induced. These results suggest that periodontitis patients have human hsp60-reactive T cells with a type I cytokine profile in their peripheral blood T-cell pools.

Genetic sources of covariation among P3(00) and online performance variables in a delayed-response working memory task

Genetic and environmental sources of covariation among the P3(00) and online performance elicited in a delayed-response working memory task, and psychometric IQ assessed by the multidimensional aptitude battery, were examined in an adolescent twin sample. An association between frontal P3 latency and task performance (phenotypic r = -0.33; genotypic r = -0.49) was indicated, with genes (i.e. twin status) accounting for a large part of the covariation ( > 70%). In contrast, genes influencing P3 amplitude mediated only a small part (2%) of the total genetic variation in task performance. While task performance mediated 15% of the total genetic variation in IQ (phenotypic r = 0.22; genotypic r = 0.39) there was no association between P3 latency and IQ or P3 amplitude with IQ. The findings provide some insight into the inter-relationships among psychophysiological, performance and psychometric measures of cognitive ability, and provide support for a levels-of-processing genetic model of cognition where genes act on specific sub-components of cognitive processes.

Growth of subtropical ECM fungi with different nitrogen sources using a new floating culture technique

Eight species of ectomycorrhizal (ECM) fungi in the genera Amanita. Gymnoboletus, Lactarius, and Russula were isolated from subtropical plant communities in eastem Australia. Two species were isolated from each of rainforest, Nothofagus forest, Eucalyptus forest, and Eucalyptus dominated wallum (heath) forest. These communities differ strongly in their soluble soil nitrogen (N) composition. The ability of the fungi to use inorganic (nitrate, ammonium) and organic (amide, peptide, protein) nitrogen sources was determined. As the fungi did not grow in liquid culture, a 'floating culture' technique was devised that allows hyphal growth on a screen floating on liquid medium. With some exceptions, fungal biomass production in floating culture closely reflected fungal growth on solid media assessed by total colony glucosamine content. Most isolates grown in floating culture had similar glucosamine concentrations on all N sources, with isolate specific concentrations ranging from 6 to 12 mug glucosamine g(-1) DW. However, Russula spp. had up to 1.7-fold higher glucosamine concentrations when growing with glutamine or ammonium compared to nitrate, glutathione or protein. Floating cultures supplied with 0.5, 1.5. 4.5, or 10 mm N mostly produced greatest biomass with 4.5 mM N. In vitro nitrate reductase activity (NRA) ranged from very low (0.03 mumol NO2- g(-1) fw h(-1)) in Russula sp. (wallum) to high (2.16 mumol NO2- g(-1) fw h(-1)) in Gymnoboletus sp. (rainforest) and mirrored the fungi's ability to use nitrate as a N source. All Russula spp. (wallum, Nothofagus and Eucalyptus forests), Lactarills sp, (rainforest) and.4manita sp. (wallum) utilized ammonium and glutamine but had little ability to use other N sources. In contrast,Amanita species (Nothofagus and Eucalyptus forests) grew on all N sources but produced most biomass with ammonium and glutamine. Only Gymnoboletus sp. (rainforest) showed similar growth with nitrate and ammonium as N sources. Fungal N source use was not associated with taxonomic groups, but is discussed in the context of soil N sources in the different habitats.

Lanczos subspace time-independent wave packet calculations of S(D-1)+H-2 reactive scattering

In this paper. we present the results of quantum dynamical simulations of the S (D-1) + H-2 insertion reaction on a newly developed potential energy surface (J. Chem. Phys. 2001, 114, 320). State-to-state reaction probabilities. product state distributions, and initial-state resolved cumulative reaction probabilities from a given incoming reactant channel are obtained from a time-independent wave packet analysis, performed within a single Lanczos subspace. Integral reaction cross sections are then estimated by J-shifting method and compared with the results from molecular beam experiment and QCT calculations.

Chebyshev real wave packet propagation: H+O-2 (J=0) state-to-state reactive scattering calculations

In this paper we explore the relative performance of two recently developed wave packet methodologies for reactive scattering, namely the real wave packet Chebyshev domain propagation of Gray and Balint-Kurti [J. Chem. Phys. 108, 950 (1998)] and the Lanczos subspace wave packet approach of Smith [J. Chem. Phys. 116, 2354 (2002); Chem. Phys. Lett. 336, 149 (2001)]. In the former method, a modified Schrodinger equation is employed to propagate the real part of the wave packet via the well-known Chebyshev iteration. While the time-dependent wave packet from the modified Schrodinger equation is different from that obtained using the standard Schrodinger equation, time-to-energy Fourier transformation yields wave functions which differ only trivially by normalization. In the Lanczos subspace approach the linear system of equations defining the action of the Green operator may be solved via either time-dependent or time-independent methods, both of which are extremely efficient due to the simple tridiagonal structure of the Hamiltonian in the Lanczos representation. The two different wave packet methods are applied to three dimensional reactive scattering of H+O-2 (total J=0). State-to-state reaction probabilities, product state distributions, as well as initial-state-resolved cumulative reaction probabilities are examined. (C) 2002 American Institute of Physics.

Transformation processes, pathways, and possible sources of distinctive polychlorinated dibenzo-p-dioxin signatures in sink environments

In recent years, studies on environmental samples with unusual dibenzo-p-dioxin (PCDD) congener profiles were reported from a range of countries. These profiles, characterized by a dominance of octachlorinated dibenzodioxin (OCDD) and relatively low in dibenzofuran (PCDF) concentrations, could not be attributed to known sources or formation processes. In the present study, the processes that result in these unusual profiles were assessed using the concentrations and isomer signatures of PCDDs from dated estuarine sediment cores in Queensland, Australia. Increases in relative concentrations of lower chlorinated PODS and a relative decrease of OCDD were correlated with time of sediment deposition. Preferred lateral, anaerobic dechlorination of OCDD represents a likely pathway for these changes. In Queensland sediments, these transformations result in a distinct dominance of isomers fully chlorinated in the 1,4,6,9-positions (1,4-patterns), and similar 1,4-patterns were observed in sediments from elsewhere. Consequently, these environmental samples may not reflect the signatures of the original source, and a reevaluation of source inputs was undertaken. Natural formation of PCDDs, which has previously been suggested, is discussed; however, based on the present results and literature comparisons, we propose an alternative scenario. This scenario hypothesizes that an anthropogenic PCDD precursor input (e.g. pentachlorophenol) results in the contamination. These results and hypothesis imply further investigations are warrented into possible anthropogenic sources in areas where natural PCDD formation has been suggested.

Consumers' perceived risk: Sources versus consequences

In this study, we examine an important factor that affects consumers' acceptance of business-to-commerce (B2C) electronic commerce - perceived risk. The objective of this paper is to examine the definition of perceived risk in the context of B2C electronic commerce. The paper highlights the importance of perceived risk and the interwoven relation between perceived risk and trust. It discusses the problem of defining perceived risk in prior B2C research. This study proposes a new classification of consumers' perceived risk based on sources. It highlights the importance of identifying the sources of consumer's risk perceptions in addition to the consequences dimensions. Two focus group discussion sessions were conducted to verify the proposed classification. Results indicate that Internet consumers perceive three sources of risk in B2C electronic commerce: technology, vendor, and product. © 2003 Elsevier B.V. All rights reserved.

The modeling of turbulent reactive flows based on multiple mapping conditioning

A new modeling approach-multiple mapping conditioning (MMC)-is introduced to treat mixing and reaction in turbulent flows. The model combines the advantages of the probability density function and the conditional moment closure methods and is based on a certain generalization of the mapping closure concept. An equivalent stochastic formulation of the MMC model is given. The validity of the closuring hypothesis of the model is demonstrated by a comparison with direct numerical simulation results for the three-stream mixing problem. (C) 2003 American Institute of Physics.

Ichthyotoxicity of Chattonella marina (Raphidophyceae) to damselfish (Acanthochromis polycanthus): the synergistic role of reactive oxygen species and free fatty acids

This investigation aimed to elucidate the relative roles of putative brevetoxins, reactive oxygen species and free fatty acids as the toxic principle of the raphidophyte Chattonella marina, using damselfish as the bioassay. Our investigations on Australian C. marina demonstrated an absence or only very low concentrations of brevetoxin-like compounds by radio-receptor binding assay and liquid chromatography-mass spectroscopy techniques. Chattonella is unique in its ability to produce levels of reactive oxygen species 100 times higher than most other algal species. However, high levels of superoxide on their own were found not to cause fish mortalities. Lipid analysis revealed this raphidophyte to contain high concentrations of the polyunsaturated fatty acid eicosapentaenoic acid (EPA; 18-23% of fatty acids), which has demonstrated toxic properties to marine organisms. Using damselfish as a model organism, we demonstrated that the free fatty acid (FFA) form of EPA produced a mortality and fish behavioural response similar to fish exposed to C. marina cells. This effect was not apparent when fish were exposed to other lipid fractions including a triglyceride containing fish oil, docosahexaenoate-enriched ethyl ester, or pure brevetoxin standards. The presence of superoxide together with low concentrations of EPA accelerated fish mortality rate threefold. We conclude that the enhancement of ichthyotoxicity of EPA in the presence of superoxide can account for the high C. marina fish killing potential. (C) 2003 Elsevier B.V All rights reserved.

A global health problem caused by arsenic from natural sources

Arsenic is a carcinogen to both humans and animals. Arsenicals have been associated with cancers of the skin, lung, and bladder. Clinical manifestations of chronic arsenic poisoning include non-cancer end point of hyper- and hypo-pigmentation, keratosis, hypertension, cardiovascular diseases and diabetes. Epidemiological evidence indicates that arsenic concentration exceeding 50 mug l(-1) in the drinking water is not public health protective. The current WHO recommended guideline value for arsenic in drinking water is 10 mug l(-1), whereas many developing countries are still having a value of 50 mug 1(-1). It has been estimated that tens of millions of people are. at risk exposing to excessive levels of arsenic from both contaminated water and arsenic-bearing coal from natural sources. The global health implication and possible intervention strategies were also discussed in this review article. (C) 2003 Elsevier Ltd. All rights reserved.