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Carlos M. Herrera Clara de Vega Azucena Canto Mar��a I. Pozo 《Annals of botany》2009,103(9):1415-1423
Background and Aims
One peculiarity of floral nectar that remains relatively unexplored from an ecological perspective is its role as a natural habitat for micro-organisms. This study assesses the frequency of occurrence and abundance of yeast cells in floral nectar of insect-pollinated plants from three contrasting plant communities on two continents. Possible correlations between interspecific differences in yeast incidence and pollinator composition are also explored.Methods
The study was conducted at three widely separated areas, two in the Iberian Peninsula (Spain) and one in the Yucatán Peninsula (Mexico). Floral nectar samples from 130 species (37–63 species per region) in 44 families were examined microscopically for the presence of yeast cells. For one of the Spanish sites, the relationship across species between incidence of yeasts in nectar and the proportion of flowers visited by each of five major pollinator categories was also investigated.Key Results
Yeasts occurred regularly in the floral nectar of many species, where they sometimes reached extraordinary densities (up to 4 × 105 cells mm−3). Depending on the region, between 32 and 44 % of all nectar samples contained yeasts. Yeast cell densities in the order of 104 cells mm−3 were commonplace, and densities >105 cells mm−3 were not rare. About one-fifth of species at each site had mean yeast cell densities >104 cells mm−3. Across species, yeast frequency and abundance were directly correlated with the proportion of floral visits by bumble-bees, and inversely with the proportion of visits by solitary bees.Conclusions
Incorporating nectar yeasts into the scenario of plant–pollinator interactions opens up a number of intriguing avenues for research. In addition, with yeasts being as ubiquitous and abundant in floral nectars as revealed by this study, and given their astounding metabolic versatility, studies focusing on nectar chemical features should carefully control for the presence of yeasts in nectar samples.Key words: Bumble-bees, floral nectar, microbial communities, pollination, yeasts‘Il y a évidemment un intérêt très grand, dans une question encore peu connue, à recenser exactement et cela dans diverse régions, les organismes qu''on rencontre.’Schoellhorn (1919, p. 155)相似文献
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Background
Resveratrol is a plant-derived polyphenol with purported protecting action on various disorders associated with aging. It has been suggested that resveratrol could exert its protective action by acting on specific plasma membrane polyphenol binding sites (Han Y.S., et al. (2006) J Pharmacol Exp Ther 318:238–245). The purpose of this study was to investigate, in human skin, the possible existence of specific binding sites that mediate the protective action of resveratrol.Methods and Findings
Using human skin tissue, we report here the presence of specific [3H]-resveratrol binding sites (KD = 180 nM) that are mainly located in the epidermis. Exposure of HaCaT cells to the nitric oxide free radical donor sodium nitroprusside (SNP; 0.3–3 mM) resulted in cell death which was reduced by resveratrol (EC50 = 14.7 µM), and to a much lesser extent by the resveratrol analogue piceatannol (EC50 = 95 µM) and epigallocatechin gallate (EC50 = 200 µM), a green-tea derived polyphenol. The protective action of resveratrol likely relates to its anti-apoptotic effect since at the same range of concentration it was able to reduce both the number of apoptotic cells as well as mitochondrial apoptotic events triggered by SNP.Conclusion
Taken together, these findings suggest that resveratrol, by acting on specific polyphenol binding sites in epidermis, may be useful to prevent skin disorders associated with aging. 相似文献4.
Lehmann LE Hauser S Malinka T Klaschik S Weber SU Schewe JC Stüber F Book M 《PloS one》2011,6(2):e17146
Background
Urinary tract infections (UTI) are frequent in outpatients. Fast pathogen identification is mandatory for shortening the time of discomfort and preventing serious complications. Urine culture needs up to 48 hours until pathogen identification. Consequently, the initial antibiotic regimen is empirical.Aim
To evaluate the feasibility of qualitative urine pathogen identification by a commercially available real-time PCR blood pathogen test (SeptiFast®) and to compare the results with dipslide and microbiological culture.Design of study
Pilot study with prospectively collected urine samples.Setting
University hospital.Methods
82 prospectively collected urine samples from 81 patients with suspected UTI were included. Dipslide urine culture was followed by microbiological pathogen identification in dipslide positive samples. In parallel, qualitative DNA based pathogen identification (SeptiFast®) was performed in all samples.Results
61 samples were SeptiFast® positive, whereas 67 samples were dipslide culture positive. The inter-methodological concordance of positive and negative findings in the gram+, gram- and fungi sector was 371/410 (90%), 477/492 (97%) and 238/246 (97%), respectively. Sensitivity and specificity of the SeptiFast® test for the detection of an infection was 0.82 and 0.60, respectively. SeptiFast® pathogen identifications were available at least 43 hours prior to culture results.Conclusion
The SeptiFast® platform identified bacterial DNA in urine specimens considerably faster compared to conventional culture. For UTI diagnosis sensitivity and specificity is limited by its present qualitative setup which does not allow pathogen quantification. Future quantitative assays may hold promise for PCR based UTI pathogen identification as a supplementation of conventional culture methods. 相似文献5.
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Vis JC De Bruin-Bon HA Bouma BJ Huisman SA Imschoot L van den Brink K Mulder BJ 《Netherlands heart journal》2012,20(6):264-269
Objective
Physical fitness is reduced in adults with Down syndrome (DS). The present study was conducted to elucidate the exercise response in adults with DS.Design
Case controlled before-after trial.Setting
Residential centre for people with intellectual disabilities.Participants
96 Adults with DS, 25 non-DS adults with an intellectual disability, 33 controls.Interventions
Echocardiography to exclude heart defects and to measure cardiac index (CI) in the supine position, supine position with raised legs, and following ten knee bends.Main outcome measure
Exercise testingResults
At rest, mean CI was not significantly different between persons with DS and controls (2.3 vs. 2.4 l/min/m2, p = 0.3). However, mean CI after exercise was significantly lower in DS (2.9 vs. 3.7 l/min/m2, p < 0.001) and mean CI increase from rest to exercise was more than 50% lower in DS. On the contrary, CI after exercise was similar among controls and non-DS adults with an intellectual disability. Significantly lower stroke volumes in DS were found with insufficient heart rate response.Conclusions
CI at rest was similar in adults with DS and controls; however persons with DS have a diminished cardiac response to exercise. Stroke volumes were significantly lower in DS during exercise and a compensated heightened heart rate was absent. 相似文献7.
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Asghar Mesbahi Vahid Jafarzadeh Nahideh Gharehaghaji 《Reports of Practical Oncology and Radiotherapy》2012,17(3):146-150
Background
Application of less toxic normoxic polymer gel of N-isopropyl acrylamide (NIPAM) for radiation therapy has been studied in recent years.Aim
In the current study the optical and NMR properties of NIPAM were studied for radiation therapy dosimetry application.Materials and methods
NIPAM normoxic polymer gel was prepared and irradiated by 9 MV photon beam of a medical linac. The optical absorbance was measured using a conventional laboratory spectrophotometer in different wavelengths ranging from 390 to 860 nm. R2 measurements of NIPAM gels were performed using a 1.5 T scanner and R2–dose curve was obtained.Results
Our results showed R2 dose sensitivity of 0.193 ± 0.01 s−1 Gy−1 for NIPAM gel. Both R2 and optical absorbance showed a linear relationship with dose from 1.5 to 11 Gy for NIPAM gel dosimeter. Moreover, absorbance–dose response varied considerably with light wavelength and highest sensitivity was seen for the blue part of the spectrum.Conclusion
Our results showed that both optical and NMR approaches have acceptable sensitivity and accuracy for dose determination with NIPAM gel. However, for optical reading of the gel, utilization of an optimum optical wavelength is recommended. 相似文献10.
Alberto Migliore Umberto Massafra Emanuele Bizzi Francesca Vacca Severino Martin-Martin Mauro Granata Andrea Alimonti Sandro Tormenta 《Arthritis research & therapy》2009,11(6):R183
Introduction
Comparison of intra-articular bacterial-derived hyaluronic acid (Hyalubrix®) (HA) with local analgesia (mepivacaine) for osteoarthritis (OA) of the hip.Methods
A pilot prospective, double-blind, 6-month randomized trial of 42 patients with hip OA. HA or mepivacaine was administered twice (once a month) under ultrasound guidance. Efficacy measurements included the Lequesne''s algofunctional index, a visual analog scale for pain, concomitant use of analgesia, patient and physician global measurement, and safety.Results
Patients in the HA group exhibited a significantly reduced Lequesne''s algofunctional index 3 and 6 months after treatment (P < 0.001) and significantly reduced visual analog scale pain scores 3 and 6 months after treatment (P < 0.05) compared with the local anesthetic group. All primary and secondary measures were significantly improved versus baseline, but other than the above were not different from each other at 3 or 6 months. Adverse effects were minimal.Conclusions
This comparative study suggests a beneficial effect and safety of intra-articular HA in the management of hip OA.Trial registration number
ISRCTN39397064. 相似文献11.
Uptake of aluminium into Arabidopsis root cells measured by fluorescent lifetime imaging 总被引:1,自引:0,他引:1
Background and Aims
Measuring the Al3+ uptake rate across the plasma membrane of intact root cells is crucial for understanding the mechanisms and time-course of Al toxicity in plants. However, a reliable method with the sufficient spatial and temporal resolution to estimate Al3+ uptake in intact root cells does not exist.Methods
In the current study, fluorescent lifetime imaging (FLIM) analysis was used to quantify Al3+ uptake in the root-cell cytoplasm in vivo. This was performed via the estimation of the fluorescence lifetime of Al–lumogallion {5-chloro-3[(2,4-dihydroxyphenyl)azo]-2-hydroxybenzenesulfonic acid} complexes and measurements of intracellular pH while exposing arabidopsis seedlings to acidic and Al3+ stresses.Key Results
The lifetime of Al–lumogallion complexes fluorescence is pH-dependent. The primary sites for Al3+ entry are the meristem and distal elongation zones, while Al3+ uptake via the cortex and epidermis of the mature root zone is limited. The maximum rates of Al uptake into the cytoplasm (2–3 µmol m−3 min−1 for the meristematic root zone and 3–7 µmol m−3 min−1 for the mature zone) were observed after a 30-min exposure to 100 µm AlCl3 (pH 4·2). Intracellular Al concentration increased to 0·4 µm Al within the first 3 h of exposure to 100 µm AlCl3.Conclusions
FLIM analysis of the fluorescence of Al–lumogallion complexes can be used to reliably quantify Al uptake in the cytoplasm of intact root cells at the initial stages of Al3+ stress.Key words: Acid stress, Al3+, aluminium toxicity, Arabidopsis thaliana, low pH, fluorescent lifetime imaging (FLIM), lumogallion 相似文献12.
Sengupta K Alluri KV Satish AR Mishra S Golakoti T Sarma KV Dey D Raychaudhuri SP 《Arthritis research & therapy》2008,10(4):R85
Introduction
5-Loxin® is a novel Boswellia serrata extract enriched with 30% 3-O-acetyl-11-keto-beta-boswellic acid (AKBA), which exhibits potential anti-inflammatory properties by inhibiting the 5-lipoxygenase enzyme. A 90-day, double-blind, randomized, placebo-controlled study was conducted to evaluate the efficacy and safety of 5-Loxin® in the treatment of osteoarthritis (OA) of the knee.Methods
Seventy-five OA patients were included in the study. The patients received either 100 mg (n = 25) or 250 mg (n = 25) of 5-Loxin® daily or a placebo (n = 25) for 90 days. Each patient was evaluated for pain and physical functions by using the standard tools (visual analog scale, Lequesne''s Functional Index, and Western Ontario and McMaster Universities Osteoarthritis Index) at the baseline (day 0), and at days 7, 30, 60 and 90. Additionally, the cartilage degrading enzyme matrix metalloproteinase-3 was also evaluated in synovial fluid from OA patients. Measurement of a battery of biochemical parameters in serum and haematological parameters, and urine analysis were performed to evaluate the safety of 5-Loxin® in OA patients.Results
Seventy patients completed the study. At the end of the study, both doses of 5-Loxin® conferred clinically and statistically significant improvements in pain scores and physical function scores in OA patients. Interestingly, significant improvements in pain score and functional ability were recorded in the treatment group supplemented with 250 mg 5-Loxin® as early as 7 days after the start of treatment. Corroborating the improvements in pain scores in treatment groups, we also noted significant reduction in synovial fluid matrix metalloproteinase-3. In comparison with placebo, the safety parameters were almost unchanged in the treatment groups.Conclusion
5-Loxin® reduces pain and improves physical functioning significantly in OA patients; and it is safe for human consumption. 5-Loxin® may exert its beneficial effects by controlling inflammatory responses through reducing proinflammatory modulators, and it may improve joint health by reducing the enzymatic degradation of cartilage in OA patients.Trail Registration
(Clinical trial registration number: ISRCTN05212803.) 相似文献13.
S. Legros I. Mialet-Serra J.-P. Caliman F. A. Siregar A. Cl��ment-Vidal M. Dingkuhn 《Annals of botany》2009,104(6):1171-1182
Background and Aims
Oil palm flowering and fruit production show seasonal maxima whose causes are unknown. Drought periods confound these rhythms, making it difficult to analyse or predict dynamics of production. The present work aims to analyse phenological and growth responses of adult oil palms to seasonal and inter-annual climatic variability.Methods
Two oil palm genotypes planted in a replicated design at two sites in Indonesia underwent monthly observations during 22 months in 2006–2008. Measurements included growth of vegetative and reproductive organs, morphology and phenology. Drought was estimated from climatic water balance (rainfall – potential evapotranspiration) and simulated fraction of transpirable soil water. Production history of the same plants for 2001–2005 was used for inter-annual analyses.Key Results
Drought was absent at the equatorial Kandista site (0°55′N) but the Batu Mulia site (3°12′S) had a dry season with variable severity. Vegetative growth and leaf appearance rate fluctuated with drought level. Yield of fruit, a function of the number of female inflorescences produced, was negatively correlated with photoperiod at Kandista. Dual annual maxima were observed supporting a recent theory of circadian control. The photoperiod-sensitive phases were estimated at 9 (or 9 + 12 × n) months before bunch maturity for a given phytomer. The main sensitive phase for drought effects was estimated at 29 months before bunch maturity, presumably associated with inflorescence sex determination.Conclusion
It is assumed that seasonal peaks of flowering in oil palm are controlled even near the equator by photoperiod response within a phytomer. These patterns are confounded with drought effects that affect flowering (yield) with long time-lag. Resulting dynamics are complex, but if the present results are confirmed it will be possible to predict them with models. 相似文献14.
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Background
Selenocysteine tRNAs (tRNASec) exhibit a number of unique identity elements that are recognized specifically by proteins of the selenocysteine biosynthetic pathways and decoding machineries. Presently, these identity elements and the mechanisms by which they are interpreted by tRNASec-interacting factors are incompletely understood.Methodology/Principal Findings
We applied rational mutagenesis to obtain well diffracting crystals of murine tRNASec. tRNASec lacking the single-stranded 3′-acceptor end (ΔGCCARNASec) yielded a crystal structure at 2.0 Å resolution. The global structure of ΔGCCARNASec resembles the structure of human tRNASec determined at 3.1 Å resolution. Structural comparisons revealed flexible regions in tRNASec used for induced fit binding to selenophosphate synthetase. Water molecules located in the present structure were involved in the stabilization of two alternative conformations of the anticodon stem-loop. Modeling of a 2′-O-methylated ribose at position U34 of the anticodon loop as found in a sub-population of tRNASec in vivo showed how this modification favors an anticodon loop conformation that is functional during decoding on the ribosome. Soaking of crystals in Mn2+-containing buffer revealed eight potential divalent metal ion binding sites but the located metal ions did not significantly stabilize specific structural features of tRNASec.Conclusions/Significance
We provide the most highly resolved structure of a tRNASec molecule to date and assessed the influence of water molecules and metal ions on the molecule''s conformation and dynamics. Our results suggest how conformational changes of tRNASec support its interaction with proteins. 相似文献16.
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Background
Although it has been widely accepted that global changes will pose the most important constrains to plant survival and distribution, our knowledge of the adaptive mechanism for plant with large-scale environmental changes (e.g. drought and high temperature) remains limited.Methodology/Principal findings
An experiment was conducted to examine anatomical and physiological plasticity in Leymus chinensis along a large-scale geographical gradient from 115° to 124°E in northeast China. Ten sites selected for plant sampling at the gradient have approximately theoretical radiation, but differ in precipitation and elevation. The significantly increasing in leaf thickness, leaf mass per area, vessel and vascular diameters, and decreasing in stoma density and stoma index exhibited more obvious xerophil-liked traits for the species from the moist meadow grassland sites in contrast to that from the dry steppe and desert sites. Significant increase in proline and soluble sugar accumulation, K+/Na+ for the species with the increasing of stresses along the gradient showed that osmotic adjustment was enhanced.Conclusion/Significance
Obvious xerophytic anatomical traits and stronger osmotic adjustment in stress conditions suggested that the plants have much more anatomical and physiological flexibilities than those in non-stress habitats along the large-scale gradient. 相似文献18.
Background
Rupture of the fetal membranes is a common harbinger of imminent labor and delivery. Telomere shortening is a surrogate for oxidative stress (OS) and senescence. Fetal leukocyte and placental membrane DNA telomere lengths were evaluated to determine their association with preterm prelabor rupture of the membranes (pPROM) or spontaneous preterm births with intact membranes (PTB), compared to term birth.Methods
Telomere lengths were quantified in cord blood leukocytes (n = 133) from three major groups: 1) pPROM (n = 28), 2) PTB (n = 69) and 3) uncomplicated full term births (controls, n = 35), using real-time quantitative PCR. Placental membrane specimens (n = 18) were used to correlate fetal leukocyte and placental telomere lengths. Telomere length differences among the groups were analyzed by ANOVA. Pearson correlation coefficients determined relationships between leukocyte and placental membrane telomere lengths.Results
In pregnancies with intact membranes, fetal leukocyte telomere length was inversely proportional to gestational age. The mean telomere length decreased as gestation progressed, with the shortest at term. pPROM had telomere lengths (9962±3124 bp) that were significantly shorter than gestational age-matched PTB (11546±4348 bp, p = 0.04), but comparable to term births (9011±2497 bp, p = 0.31). Secondary analyses revealed no effects of race (African American vs. Caucasian) or intraamniotic infection on telomere length. A strong Pearson''s correlation was noted between fetal leukocyte and placental membrane telomere lengths (ρ = 0.77; p<0.01).Conclusions
Fetal leukocyte telomere length is reduced in pPROM compared to PTB but is similar to term births. pPROM represents a placental membrane disease likely mediated by OS-induced senescence. 相似文献19.
Tabu C Breiman RF Ochieng B Aura B Cosmas L Audi A Olack B Bigogo G Ongus JR Fields P Mintz E Burton D Oundo J Feikin DR 《PloS one》2012,7(2):e31237