| 1. |
- Duong Phan, Ngoc Chau, et al.
(författare)
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Accurate sampling of PCDD/F in high temperature flue-gas using cooled sampling probes
- 2012
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Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 88:7, s. 832-836
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Tidskriftsartikel (refereegranskat)abstract
- In a laboratory-scale combustion reactor, flue-gas samples were collected at two temperatures in the post-combustion zone, 700 °C and 400 °C, using two different water-cooled sampling probes. The probes were the cooled probe described in the European Standard method EN-1948:1, referred to as the original probe, and a modified probe that contained a salt/ice mixture to assist the cooling, referred to as the sub-zero probe. To determine the efficiency of the cooling probes, internal temperature measurements were recorded at 5 cm intervals inside the probes. Flue-gas samples were analyzed for polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs). Samples collected at 700 °C using the original cooling probe showed higher concentrations of PCDD/Fs compared to samples collected using the sub-zero probe. No significant differences were observed between samples collected at 400 °C. The results indicated that artifact formation of PCDD/Fs readily occurs during flue-gas sampling at high temperatures if the cooling within the probe is insufficient, as found for the original probe at 700 °C. It was also shown that this problem could be alleviated by using probes with an enhanced cooling capacity, such as the sub-zero probe.Although this may not affect samples collected for regulatory purposes in exit gases, it is of great importance for research conducted in the high-temperature region of the post-combustion zone.
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| 2. |
- Isaksson, Hanna, et al.
(författare)
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High-fiber rye diet increases ileal excretion of energy and macronutrients compared with low-fiber wheat diet independent of meal frequency in ileostomy subjects
- 2013
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Ingår i: Food & Nutrition Research. - Järfälla : Co-Action Publishing. - 1654-6628 .- 1654-661X. ; 57, s. 18519-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Whole-grain foods and cereal dietary fiber intake is associated with lower body weight. This may partly result from lower energy utilization of high-fiber diets. Objective: In the present study, the impact on ileal excretion of energy and macronutrients in response to a rye bread high-fiber diet compared to a refined wheat low-fiber diet was investigated. Furthermore, the effect of meal frequency on apparent absorption of nutrients was studied for the first time. Design: Ten participants that had undergone ileostomy consumed standardized iso-caloric diets, including low-fiber wheat bread (20 g dietary fiber per day) for 2 weeks followed by high-fiber rye bread (52 g dietary fiber per day) for 2 weeks. The diets were consumed in an ordinary (three meals per day) and a nibbling (seven meals per day) meal frequency in a cross-over design. Ileal effluents were collected during 24 h at the third day of each of the four dietary periods and analyzed for gross energy and nutrient contents. Results: The results showed that intake of rye bread high-fiber diet compared to the refined wheat low-fiber diet caused an increase in ileal excretion of energy and macronutrients. The effect was independent of meal frequency. This suggests that a high intake of rye may result in lower availability of macronutrients for small intestinal digestion and absorption. A regular intake of rye may therefore have implications for weight management.
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| 3. |
- Jonsson, Hans, et al.
(författare)
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Genome sequence of segmented filamentous bacteria present in the human intestine
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Segmented filamentous bacteria (SFB) are unique immune modulatory bacteria colonizing the small intestine of a variety of animals in a host-specific manner. SFB exhibit filamentous growth and attach to the host's intestinal epithelium, offering a physical route of interaction. SFB affect functions of the host immune system, among them IgA production and T-cell maturation. Until now, no human-specific SFB genome has been reported. Here, we report the metagenomic reconstruction of an SFB genome from a human ileostomy sample. Phylogenomic analysis clusters the genome with SFB genomes from mouse, rat and turkey, but the genome is genetically distinct, displaying 65-71% average amino acid identity to the others. By screening human faecal metagenomic datasets, we identified individuals carrying sequences identical to the new SFB genome. We thus conclude that a unique SFB variant exists in humans and foresee a renewed interest in the elucidation of SFB functionality in this environment.
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| 4. |
- Lundin, Daniel, et al.
(författare)
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Which sequencing depth is sufficient to describe patterns in bacterial alpha- and beta-diversity?
- 2012
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Ingår i: Environmental Microbiology Reports. - : Wiley. - 1758-2229 .- 1758-2229. ; 4:3, s. 367-372
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Tidskriftsartikel (refereegranskat)abstract
- The vastness of microbial diversity implies that an almost infinite number of individuals needs to be identified to accurately describe such communities. Practical and economical constraints may therefore prevent appropriate study designs. However, for many questions in ecology it is not essential to know the actual diversity but rather the trends among samples thereof. It is, hence, important to know to what depth microbial communities need to be sampled to accurately measure trends in diversity. We used three data sets of freshwater and sediment bacteria, where diversity was explored using 454 pyrosequencing. Each data set contained 615 communities from which 15 00020 000 16S rRNA gene sequences each were obtained. These data sets were subsampled repeatedly to 10 different depths down to 200 sequences per community. Diversity estimates varied with sequencing depth, yet, trends in diversity among samples were less sensitive. We found that 1000 denoised sequences per sample explained to 90% the trends in beta-diversity (Bray-Curtis index) among samples observed for 15 00020 000 sequences. Similarly, 5000 denoised sequences were sufficient to describe trends in a-diversity (Shannon index) with the same accuracy. Further, 5000 denoised sequences captured to more than 80% the trends in Chao1 richness and Pielou's evenness.
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| 5. |
- Öhrvik, Veronica, et al.
(författare)
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Folate bioavailability from breads and a meal assessed with a human stable-isotope area under the curve and ileostomy model.
- 2010
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Ingår i: American Journal of Clinical Nutrition. - : Elsevier BV. - 0002-9165 .- 1938-3207. ; 92:3, s. 532-538
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Recent data revealed differences in human absorption kinetics and metabolism between food folates and folic acid supplements and fortificant.OBJECTIVE: The objective was to determine folate bioavailability after ingestion of breads or a breakfast meal fortified with either 5-CH(3)-H(4) folate or folic acid by using a stable-isotope area under the curve (AUC) and ileostomy model.DESIGN: In a randomized crossover trial, healthy ileostomists (n = 8) ingested single doses of whole-meal bread that contained ap 450 nmol (200 micro g) of either (6S)-[(13)C(5)]5-CH(3)-H(4) folate or [(13)C(5)]folic acid or a breakfast meal that contained ap 450 nmol (200 micro g) [(13)C(5)]folic acid. We collected blood from the subjects during 12 h postdose for assessment of plasma kinetics. Nonabsorbed folate was assessed from labeled folate contents in stomal effluent 12 and 24 h postdose.RESULTS: The median (range) plasma AUC(0 rarr 12) (AUC from 0 to 12 h after ingested dose) of 66 nmol sdot h/L (34-84 nmol sdot h/L) after ingestion of bread that contained (6S)-[(13)C(5)]5-CH(3)-H(4) folate was significantly greater (P lt 0.001) than that after ingestion of [(13)C(5)]folic acid in fortified bread [28 nmol sdot h/L (15-38 nmol sdot h/L)] and a fortified breakfast meal [26 nmol sdot h/L (15-60 nmol sdot h/L)]. Both labeled doses resulted in increases of plasma [(13)C(5)]5-CH(3)-H(4) folate. However, the kinetic variables C(max) (maximum plasma concentration) and T(max) [time (min) of maximum plasma concentration] varied after ingestion of the different folate forms. The stomal folate content was lt 10% of the ingested dose and did not vary significantly after ingestion of test foods that contained (6S)-[(13)C(5)]5-CH(3)-H(4) folate [median (range): 13 nmol (10-31 nmol)] or [(13)C(5)]folic acid [median (range): 25 nmol (8-42 nmol)] (P = 0.33).CONCLUSIONS: Our data confirm differences in plasma absorption kinetics for reduced folates and synthetic folic acid administered with the test foods. Stomal folate contents indicated almost complete bioavailability of labeled folate from the breads or breakfast meal.
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