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  • 1
    Electronic Resource
    Electronic Resource
    Determination of ground- and excited-state isomerization barriers for the oligothiophene 3',4'-dibutyl-2,2':5',2''-terthiophene (1993)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 115 (1993), S. 12158-12164 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00078a064
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  • 2
    Electronic Resource
    Electronic Resource
    Polyfuran: a new synthetic approach and electronic properties (1993)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 115 (1993), S. 12519-12525 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00079a035
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  • 3
    Electronic Resource
    Electronic Resource
    pH-Dependent regulation of leukocyte 5-lipoxygenase activity in inflammatory exudates by albumin (1997)
    Springer
    Inflammation research 46 (1997), S. 366-372 
    Details
    ISSN: 1420-908X
    Keywords: Key words: Neutrophils — Inflammation — In vivo animal models — Lipid mediators — Inflammatory mediators
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Objective and Design: In order to study the regulation of cellular 5-lipoxygenase activity under inflammatory conditions, the effects of inflammatory exudates on rat leukocyte 5 lipoxygenase activity were investigated.¶Materials: Peritoneal leukocytes and inflammatory exudates were collected from glycogen treated rats.¶Treatment: Glycogen (1 g/kg body weight, in a final volume of 3 ml PBS) was injected intraperitoneally into male Wistar rats. After 4 h, the inflammatory exudate was collected.¶Methods: Rat peritoneal leukocytes were isolated and the cellular 5-lipoxygenase activity was determined by HPLC after cell stimulation with calcium ionophore A23187.¶Results: Inflammatory exudates from glycogen treated animals strongly inhibited cellular 5-lipoxygenase activity of ionophore challenged leukocytes. Albumin was identified as the inhibitor in exudates. Inhibition of cellular 5-lipoxygenase activity by albumin was pH-dependent and was strongly increased by the alkaline pH (7.9–8.0) of the exudate. The albumin effect increased in the range of pH 7.4–8.2 where albumin undergoes a conformational change called neutral to base (N–B) transition. S-Carboxymethylalbumin had a similar activity to that of albumin, which indicated that the free SH-group at Cys-34 of albumin is not necessary for the effect. The albumin dimer showed a significantly higher inhibition than albumin and it suppressed cellular 5-lipoxygenase activity by 98%. Peptic and tryptic fragments of albumin which comprise domains I, II and II, III, respectively, were less active or inactive. Thus, an intact albumin molecule or the dimer are required for efficient inhibition of cellular 5-lipoxygenase activity.¶Conclusions: Our data suggest that during inflammation, albumin extravasation and changes in pH-value are involved in the regulation of the inflammatory reaction by suppression of leukotriene release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000110050203
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  • 4
    Electronic Resource
    Electronic Resource
    Anaerobic and aerobic oxidation of ferrous iron at neutral pH by chemoheterotrophic nitrate-reducing bacteria (1998)
    Springer
    Archives of microbiology 169 (1998), S. 159-165 
    Details
    ISSN: 1432-072X
    Keywords: Key words Iron oxidation ; Ferrous iron ; Ferric iron ; Nitrate reduction ; Sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nine out of ten anaerobic enrichment cultures inoculated with sediment samples from various freshwater, brackish-water, and marine sediments exhibited ferrous iron oxidation in mineral media with nitrate and an organic cosubstrate at pH 7.2 and 30° C. Anaerobic nitrate-dependent ferrous iron oxidation was a biological process. One strain isolated from brackish-water sediment (strain HidR2, a motile, nonsporeforming, gram-negative rod) was chosen for further investigation of ferrous iron oxidation in the presence of acetate as cosubstrate. Strain HidR2 oxidized between 0.7 and 4.9 mM ferrous iron aerobically and anaerobically at pH 7.2 and 30° C in the presence of small amounts of acetate (between 0.2 and 1.1 mM). The strain gained energy for growth from anaerobic ferrous iron oxidation with nitrate, and the ratio of iron oxidized to acetate provided was constant at limiting acetate supply. The ability to oxidize ferrous iron anaerobically with nitrate at approximately pH 7 appears to be a widespread capacity among mesophilic denitrifying bacteria. Since nitrate-dependent iron oxidation closes the iron cycle within the anoxic zone of sediments and aerobic iron oxidation enhances the reoxidation of ferrous to ferric iron in the oxic zone, both processes increase the importance of iron as a transient electron carrier in the turnover of organic matter in natural sediments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050555
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  • 5
    Electronic Resource
    Electronic Resource
    Validation of questions on asthma and wheeze in farming and anthroposophic children (2005)
    Oxford, UK : Blackwell Science Ltd
    Clinical & experimental allergy 35 (2005), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background In most epidemiological surveys the estimated prevalence of asthma is based on questionnaire responses, which may depend on the individual's perception as well as medical consulting habits in a given population. Therefore, measurement of bronchial hyper-responsiveness as a key feature of asthma has been suggested as an objective parameter for asthma.Objective The aim of the present study was to validate questionnaire responses on asthma and wheeze against bronchial response to hypertonic saline (HS) (4.5%) in populations previously shown to have a lower prevalence of asthma and allergies: farmers' children and children from anthroposophic families.Methods Children whose parents had completed a written questionnaire in the cross-sectional PARSIFAL-study were drawn from the following four subgroups: ‘farm children’ (n=183), ‘farm reference children’ (n=173), ‘Steiner schoolchildren’ (n=243) and ‘Steiner reference children’ (n=179). Overall, 319 children with wheeze in the last 12 months and 459 children without wheeze in the last 12 months performed an HS challenge.Results Odds ratios, sensitivity, specificity, likelihood ratios and measures of association did not differ significantly between the four subgroups. The correlation between the bronchial response to HS and wheeze and asthma questions was moderate and similar for farm children, farm reference children, Steiner schoolchildren and Steiner reference children (κ for ‘wheeze’: 0.25, 0.33, 0.31, 0.35, respectively, P=0.754, κ for ‘doctor's diagnosis of asthma’: 0.33, 0.19, 0.33, 032, respectively, P=0.499).Conclusion The findings from this study suggest that the reliabilitiy of questionnaire responses on asthma and wheeze is comparable between farmers' children, children raised in families with anthroposophic lifestyle and their respective peers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2222.2005.02308.x
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  • 6
    Electronic Resource
    Electronic Resource
    Bacterial and fungal agents in house dust and wheeze in children: the PARSIFAL study (2005)
    Oxford, UK : Blackwell Science Ltd
    Clinical & experimental allergy 35 (2005), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Growing up on a farm and an anthroposophic lifestyle are associated with a lower prevalence of allergic diseases in childhood. This might be related to increased inhalatory exposure to microbial agents.Objective To assess the association between microbial agents in house dust and atopic wheeze in farm children, Steiner school children and reference children.Methods Levels of bacterial endotoxin, fungal β(1,3)-glucans and fungal extracellular polysaccharides (EPS) in mattress and living room floor dust were measured in a population of 270 atopic (=Phadiatop-positive) children with self-reported wheezing, including 168 current atopic wheezers, and 441 non-atopic, non-symptomatic controls. These children were selected from a cross-sectional study in five European countries.Results In the study population as a whole, average levels of mattress dust endotoxin, EPS and glucans were slightly (1.1–1.2-fold; P〈0.10) higher in control children than in atopic wheezers. Atopic wheeze was related to mattress levels of endotoxin, EPS and glucans in farm and farm-reference children. However, when adjusting for group (farm vs. farm-reference children), the associations became non-significant whereas the group effect remained. No associations between atopic wheeze and microbial agents were observed in Steiner and Steiner-reference children. For current atopic wheeze, the farm effect became non-significant after adjustment for microbial agent levels.Conclusion Not only bacterial endotoxin but also mould components might offer some protection against atopic wheeze in children. However, the protective effect of being raised on a farm was largely unexplained by the mattress microbial agent levels measured in this study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2222.2005.02339.x
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  • 7
    Electronic Resource
    Electronic Resource
    ESR as a fast technique to dissolve nitrogen-rich inclusions in titanium (1999)
    Springer
    Materials research innovations 2 (1999), S. 364-368 
    Details
    ISSN: 1433-075X
    Keywords: Key words Titanium ; Nitrogen-rich inclusions ; Titanium nitride ; TiN ; Hard-alpha ; Refining ; Electroslag refining ; ESR ; Ultrasonic inspection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Nitrogen-rich inclusions can lead to a reduction in fatigue life of highly stressed titanium-alloy components (found in the compressor sections of power generation gas turbines, turbine sections of power generation steam turbines, wing sections of aircraft air frames, and compressor and fan sections of aircraft jet engines, for example). It is the ”crack starting” nature of the nitrogen-rich inclusions that is the problem, not the presence of nitrogen in the system, per se. This paper covers the theory and laboratory experiments used to evaluate ESR (electro-slag refining) as an alternative technique for rapid dissolution of nitrogen-rich inclusions in titanium and titanium alloys. Five variations of melt rate, slag temperature and inclusion type were evaluated. One variant showed complete dissolution of the inclusions. Several of the other variants showed partial dissolution of the inclusions. The kinetics were observed to occur at a rate 100 to 1000 times faster than the rate of dissolution of nitrogen-rich inclusions by immersion in liquid titanium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100190050115
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  • 8
    Electronic Resource
    Electronic Resource
    Aggregation of oral bacteria by human salivary mucins in comparison to salivary and gastric mucins of animal origin (1990)
    Springer
    Antonie van Leeuwenhoek 58 (1990), S. 255-263 
    Details
    ISSN: 1572-9699
    Keywords: aggregation ; animal mucins ; human salivary mucin ; oral bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seventeen strains of oral bacteria of the genera Actinomyces (5), Bacteroides (3), and Streptococcus (9) were tested for aggregation by the human whole salivary mucin fraction (HWSM) in comparison to three types of animal mucin preparations from submandibular glands of cow (BSM) and sheep (OSM), and from the stomach of pig (PGM). Considerable variation was seen with respect to the rate and titer of aggregation induced by these mucins. The aggregating activity of HWSM varied widely among the different bacterial strains. The Bacteroides group showed hardly any induced aggregation, whereas the final aggregation titers varied for S. sanguis (3 strains) between 12 and 48, for S. oralis (3 strains) between 6 and 48, for the S. mutans group (3 strains) between 6 and 96, and for the five Actinomyces strains even between 6 and 192. For a particular strain, similar differences in titer were seen between the four mucins. For a human salivary mucin (MG-2) it has been described that sialic acid in the sequence NeuAc (α2,3)Gal(β1,3)GalNac- was specifically involved in the interaction with S. sanguis strains, in contrast to S. rattus BHT. Our results, however, indicate that this sugar sequence is not a prerequisite for the aggregation of S. sanguis, as animal mucins, devoid of this structure, were equally well or even better capable of inducing aggregation. On the other hand, desialization of BSM and OSM largely abolished their aggregating capability towards S. rattus BHT. Moreover, it was found that BSM and OSM, which are comparable with respect to their major oligosaccharide structure, show considerable differences in aggregating activity towards the same bacterial strain. The results indicate that the interaction and aggregation of oral bacteria with mucins is not necessarily dictated by specific oligosaccharide structures of the mucins, but may be caused instead by common physico-chemical features of the mucins as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399337
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  • 9
    Electronic Resource
    Electronic Resource
    Aggregation of 27 oral bacteria by human whole saliva (1989)
    Springer
    Antonie van Leeuwenhoek 55 (1989), S. 277-290 
    Details
    ISSN: 1572-9699
    Keywords: Actinomyces ; aggregation ; Bacteroides ; oral bacteria ; saliva ; Streptococcus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Twenty-seven oral strains of the genera Actinomyces (5), Bacteroides (3), and Streptococcus (19) were tested for aggregation by human whole saliva, as well as the effect of culture medium, Ca-ions, and bacteria concentration thereupon. Of the media tested, GF-broth gave rise to less interference by autoaggregation or higher aggregation titers than BHI and TSB, and was used throughout this study. In most cases, Ca-ions (1 mM) only enhanced the rate of induced aggregation, whereas raising the bacteria concentration increased the rate of both induce- and autoaggregation. The final titers, ranging from 1–64, were hardly affected by these parameters, except those of S. rattus HG 59 and S. mutans HG 199, which were respectively increased and decreased by Ca-ions. Saliva-induced aggregation was observed for 21 strains of A. viscosus, A. naeslundii, A. israelii, B. gingivalis, B. intermedius, S. cricetus, S. mutans, S. rattus, S. sanguis, and S. sobrinus, mostly within 15 min to 3 h. Seventeen of these strains also showed autoaggregation, usually well after the onset of induced aggregation. Any potential induced aggregation of B. gingivalis HG 91 was always masked by autoaggregation, as well as that of the S. mutans strains under a particular set of conditions. The aggregation rate and titer varied considerably in a mutually unrelated and strain-dependent way. These microtiterplate data were matched by the 5 spectrophotometric patterns observed for saliva-bacterial interaction, which moreover, gave the better differentiation between induced and autoaggregation. In conclusion, most strains tested can show rapid saliva-induced aggregation in a strain-dependent way, yet strongly affected by the experimental conditions and interference from autoaggregation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393856
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  • 10
    Electronic Resource
    Electronic Resource
    Comparison of different assays for the aggregation of oral bacteria by human whole saliva (1989)
    Springer
    Antonie van Leeuwenhoek 55 (1989), S. 109-122 
    Details
    ISSN: 1572-9699
    Keywords: aggregation ; microtiterplate assay ; oral bacteria ; phase-contrast microscopy ; saliva ; spectrophotometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For comparison, human whole saliva-induced aggregation was studied by phase-contrast microscopy, spectrophotometry combined with macroscopic observations, and in microtiterplate assay under identical experimental conditions for Actinomyces viscosus HG 85 (T14-V) and HG 380 (T14-AV), Bacteroides gingivalis HG 66 (W 83), Streptococcus rattus HG 59 (BHT), and Streptococcus sanguis I HG 169. The entire process of formation, extension, and sedimentation of aggregates could merely be observed by the combination of these assays. The very first stages of aggregation could only be detected and quantitated by phase-contrast microscopy. Within 2 1/2 min. 50% of the A. viscosus, S. rattus, and S. sanguis cells were aggregated, denoted as T50. In microtiterplates, however, aggregates were observed in general only after sedimentation at 30–45 min of incubation, expressed as TA. For interpretation of the spectrophotometric curves, additional microscopic and macroscopic data were a prerequisite. The small decline in absorbance during the first 30–45 min (phase 1) corresponded to the formation and extension of non-sedimenting aggregates, whereas the subsequent pronounced fall in absorbance (phase 2) was caused by the massive sedimentation of aggregates. The moment of inflexion between both phases, TI, marked the onset of sedimentation of aggregates and corresponded very well with TA, at which time already 92–98% of the cells were aggregated as quantitated by microscopy. In conclusion, only by microscopy the formation and extension of aggregates could be observed within a few minutes and quantitated in terms of aggregation rate. From 30–45 min, merely the sedimentation of aggregates was visualized in microtiterplates, whereas the time course of the overall process was recorded indirectly by spectrophotometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00404751
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