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911.
BACKGROUND: Damp conditions indoors favour the growth of microorganisms, and these contain several agents that may cause inflammation when inhaled. Moulds contain a polyglucose in their cell wall, defined as (1-->3)-beta-D-glucan, exhibiting effects on inflammatory cells. AIM: The aim of the present study was to evaluate whether an inhalation challenge to purified (1-->3)-beta-D-glucan (grifolan) in humans could induce effects on inflammatory markers in blood, and to evaluate whether the reactions were related to the home exposure to (1-->3)-beta-D-glucan. METHODS: Seventeen subjects in homes with high levels of airborne (1-->3)-beta-D-glucan (G-high) and 18 subjects in homes with low levels of (1-->3)-beta-D-glucan (G-low) underwent two randomised, double-blind inhalation challenges, one to (1-->3)-beta-D-glucan suspended in saline and one to saline alone. A blood sample was taken before and after the challenges, and differential cell count, granulocyte enzymes in serum and the secretion of cytokines from peripheral blood mononuclear cells (PBMC) were measured. RESULTS: Inhalation challenge with (1-->3)-beta-D-glucan induced a decrease in the secretion of tumour necrosis factor alpha from endotoxin-stimulated PBMC in the G-high group as well as in the G-low group. In the G-high group, the inhalation of (1-->3)-beta-D-glucan induced an increase in blood lymphocytes that was significantly different from the saline-induced effect. CONCLUSIONS: The results suggest that an inhalation challenge to (1-->3)-beta-D-glucan has an effect on inflammatory cells and this effect may be related to a chronic exposure to moulds at home. 相似文献
912.
913.
Individual differences in sensitivity to the putative human pheromone androstadienone were investigated in three experiments. In experiment 1, the absolute detection threshold for androstadienone was determined to be 211 micro M using the method of constant stimuli. Detection for the related compound estratetraenol was also investigated but a threshold could not be determined. In experiment 2, using an adaptive threshold test on 100 participants, the sensitivity distribution for androstadienone, but not for the reference odor phenylethyl alcohol, was bimodal, with a smaller group of individuals with a high sensitivity to androstadienone (supersmellers). A lack of correlation between thresholds for androstadienone and phenylethyl alcohol further suggested that the bimodality for androstadienone was not due to individuals with a high general olfactory sensitivity. In line with an earlier observation, there was a statistical tendency for women to be more sensitive to androstadienone than men. Results of experiment 3 preclude the possibility that the bimodal sensitivity distribution for androstadienone would depend on individual differences in trigeminal activation. Altogether, the current study suggests that olfactory sensitivity to androstadienone is bimodally distributed in the population with a subgroup consisting of highly sensitive people. 相似文献
914.
Shikimate 5-dehydrogenase (SKDH; EC 1.1.1.25) catalyzes the reversible reduction of 3-dehydroshikimate to shikimate and is a key enzyme in the aromatic amino acid biosynthesis pathway. The shikimate 5-dehydrogenase gene, aroE, from Archaeoglobus fulgidus was cloned and overexpressed in Escherichia coli. The recombinant enzyme purified as a homodimer and yielded a maximum specific activity of 732 U/mg at 87 degrees C (with NADP+ as coenzyme). Apparent Km values for shikimate, NADP+, and NAD+ were estimated at 0.17+/-0.03 mM, 0.19+/-0.01 mM, and 11.4+/-0.4 mM, respectively. The half-life of the A. fulgidus SKDH is 2 h at the assay temperature (87 degrees C) and 17 days at 60 degrees C. Addition of 1 M NaCl or KCl stabilized the enzyme's half-life to approximately 70 h at 87 degrees C and approximately 50 days at 60 degrees C. This work presents the first kinetic analysis of an archaeal SKDH. 相似文献
915.
Ecosystem-level experiments on the effects of atmospheric CO2 enrichment and N deposition on forest trees are urgently needed. Here we present data for nine model ecosystems of spruce (Picea abies) on natural nutrient-poor montane forest soil (0.7 m2 of ground and 350 kg weight). Each system was composed of six 7-year-old (at harvest) trees each representing a different genotype, and a herbaceous understory layer (three species). The model ecosystems were exposed to three different CO2 concentrations (280, 420, 560 μl l−1) and three different rates of wet N deposition (0, 30, 90 kg ha−1 year−1) in a simulated annual course of Swiss montane climate for 3 years. The total ecosystem biomass was not affected by CO2 concentration, but increased with increasing N deposition. However, biomass allocation to roots increased with increasing CO2 leading to significantly lower leaf mass ratios (LMRs) and leaf area ratios (LARs) in trees grown at elevated CO2. In contrast to CO2 enrichment, N deposition increased biomass allocation to the aboveground plant parts, and thus LMR and LAR were higher with increasing N deposition. We observed no CO2 × N interactions on growth, biomass production, or allocation, and there were also no genotype × treatment interactions. The final leaf area index (LAI) of the spruce canopies was 19% smaller at 420 and 27% smaller at 560 than that measured at 280 μl CO2 l−1, but was not significantly altered by increasing N deposition. Lower LAIs at elevated CO2 largely resulted from shorter branches (less needles per individual tree) and partially from increased needle litterfall. Independently of N deposition, total aboveground N content in the spruce communities declined with increasing CO2 (−18% at 420 and −31% at 560 compared to 280 μl CO2 l−1). N deposition had the opposite effect on total above ground N content (+18% at 30 and +52% at 90 compared to 0 kg N ha−1 year−1). Our results suggest that under competitive conditions on natural forest soil, atmospheric CO2 enrichment may not lead to higher ecosystem biomass production, but N deposition is likely to do so. The reduction in LAI under elevated CO2 suggests allometric down-regulation of photosynthetic carbon uptake at the canopy level. The strong decline in the tree nitrogen mass per unit ground area in response to elevated CO2 may indicate CO2-induced reductions of soil N availability. Received: 11 May 1997 / Accepted: 4 August 1997 相似文献
916.
Gödecke S Roderigo C Rose CR Rauch BH Gödecke A Schrader J 《American journal of physiology. Cell physiology》2012,302(6):C915-C923
ATP and its degradation products play an important role as signaling molecules in the vascular system, and endothelial cells are considered to be an important source of nucleotide release. To investigate the mechanism and physiological significance of endothelial ATP release, we compared different pharmacological stimuli for their ability to evoke ATP release from first passage cultivated human umbilical vein endothelial cells (HUVECs). Agonists known to increase intracellular Ca(2+) levels (A23187, histamine, thrombin) induced a stable, non-lytic ATP release. Since thrombin proved to be the most robust and reproducible stimulus, the molecular mechanism of thrombin-mediated ATP release from HUVECs was further investigated. ATP rapidly increased with thrombin (1 U/ml) and reached a steady-state level after 4 min. Loading the cells with BAPTA-AM to capture intracellular calcium suppressed ATP release. The thrombin-specific, protease-activated receptor 1 (PAR-1)-specific agonist peptide TFLLRN (10 μM) fully mimicked thrombin action on ATP release. To identify the nature of the ATP-permeable pathway, we tested various inhibitors of potential ATP channels for their ability to inhibit the thrombin response. Carbenoxolone, an inhibitor of connexin hemichannels and pannexin channels, as well as Gd(3+) were highly effective in blocking the thrombin-mediated ATP release. Specifically targeting connexin43 (Cx43) and pannexin1 (Panx1) revealed that reducing Panx1 expression significantly reduced ATP release, while downregulating Cx43 was ineffective. Our study demonstrates that thrombin at physiological concentrations is a potent stimulus of endothelial ATP release involving PAR-1 receptor activation and intracellular calcium mobilization. ATP is released by a carbenoxolone- and Gd(3+)- sensitive pathway, most likely involving Panx1 channels. 相似文献
917.
Summary During the main period of citric acid fermentation byAspernillus niger product formation is easily determinable from oxygen uptake and carbon dioxide output rates. This was applied in a study on the response of citrate formation to shifts of some environmental parameters of known importance during fermentation. 相似文献
918.
Nezhun Gören Ayhan Ulubelen Jasmin Jakupovic Ferdinand Bohlmann Michael Grenz 《Phytochemistry》1984,23(10):2281-2284
In addition to known compounds an investigation of the fruits of Smyrnium rotundifolium afforded four new germacrane derivatives, all closely related to glechomanolide, one being a secogermacrane anhydride. The new compounds were 8,9-epoxy-8,9-secoglechomanolide, 1β,10α-epoxy-4-methoxy-8-hydroxyglechomanolide and 8-oxo-8,9-secoglechomanolide. The structures were assigned by spectral methods as well as by some chemical reactions. 相似文献
919.
Pedrotta Tiziana Gobet Erika Schwörer Christoph Beffa Giorgia Butz Christoph Henne Paul D. Morales-Molino César Pasta Salvatore van Leeuwen Jacqueline F. N. Vogel Hendrik Zwimpfer Elias Anselmetti Flavio S. Grosjean Martin Tinner Willy 《Vegetation History and Archaeobotany》2021,30(6):789-813
Vegetation History and Archaeobotany - Knowledge about the vegetation history of Sardinia, the second largest island of the Mediterranean, is scanty. Here, we present a new sedimentary record... 相似文献
920.
Ádám Kőrösi László Somay Zoltán Elek Viktor Markó Miklós Sárospataki Réka Bakos Ákos Varga Katinka Nyisztor András Báldi 《Agricultural and Forest Entomology》2016,18(1):68-75
- Pollination is an important ecosystem service because many agricultural crops such as fruit trees are pollinated by insects. Agricultural intensification, however, is one of the main drivers resulting in a serious decline of pollinator populations worldwide.
- In the present study, pollinator communities were examined in 12 apple orchards surrounded by either homogeneous or heterogeneous landscape in Hungary. Pollinators (honey bees, wild bees, hoverflies) were surveyed in the flowering period of apple trees. Landscape heterogeneity was characterized within a radius of 300, 500 and 1000 m around each orchard using Shannon's diversity and Shannon's evenness indices.
- We found that pollination success of apple was significantly related to the species richness of wild bees, regardless the dominance of honey bees.
- Diversity of the surrounding landscape matrix had a marginal positive effect on the species richness of hoverflies within a radius of 300 m and a positive effect on the species richness of wild bees within a radius of 500 m, whereas evenness of the surrounding landscape enhanced the abundance of wild bees within a radius of 500 m. Flower resources in the groundcover within the orchards supported honey bees.
- Therefore, the maintenance of semi‐natural habitats within 500 m around apple orchards is highly recommended to enhance wild pollinator communities and apple production.