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- Sandberg, A.-S., et al.
(author)
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High dietary calcium level decreases colonic phytate degradation in pigs fed a rapeseed diet
- 1993
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In: Journal of Nutrition. - 0022-3166 .- 1541-6100. ; 123:3, s. 559-566
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Journal article (peer-reviewed)abstract
- The degradation of phytate (inositol hexaphosphate) in rapeseed meal diet not containing phytase activity was studied in 15 growing ileum-fistulated pigs. Stomach and small intestinal degradation and total gastrointestinal degradation were compared. The effect of addition of calcium carbonate to the rapeseed meal diet at two levels (9.2 and 18.5 g/kg diet) was investigated. A commercial barley-wheat-soybean diet with intrinsic phytase activity was used as reference. Phytate and its hydrolysis products in diets, ileal digesta and feces were determined by HPLC ion-pair chromatography. Hydrolysis of phytate in the stomach and small intestine was 35-45% in pigs fed the rapeseed meal diet independent of calcium addition, and 65% in pigs fed the reference diet. Total gastrointestinal degradation of phytate in pigs fed the rapeseed diet was 97, 77 and 42% (P < 0.001) when calcium intakes were 4.5, 9.9 and 15 g/d, respectively; total gastrointestinal degradation was 72% in pigs fed the reference diet. The intestinal phytate degradation pattern, when rapeseed diet was fed, indicated the activity of an unspecific phosphatase, whereas that of the reference diet indicated intrinsic dietary phytase activity. We conclude that dietary supplementation of calcium carbonate decreases the phytate degradation in the colon of pigs, but not in the stomach and small intestine.
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- Sandberg, Ulf, 1946-, et al.
(author)
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The Art of Measuring Noise from Vehicle Tires
- 1993
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In: Proceedings of the 1993 Noise and Vibration Conference. - 400 Commonwealth Drive, Warrendale, PA, United States : Society of Automotive Engineers. ; , s. 93-111
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Conference paper (peer-reviewed)abstract
- During the latest decades tirelroad noise has been recognized as one of the most significant parts of road traffic noise. It has therefore become necessary to employ suitable noise reduction measures on tires as well as road surfaces which do not impose safety problems. Since many of these measures rely on appropriate measuring methods, several activities in order to standardize such methods for tirelroad noise have started.The paper begins with a systematic analysis of the rather complicated tire/road noise problem and suggests ways to solve it. Then a review is presented of the major measuring methods considered for standardization with regard to classification of tires:The coast-by methodThe trailer methodThe laboratory drum methodThe trailer coast-by methodThe advantages and disadvantages as well as which applications are the most suitable for each one are discussed. Particular attention is paid to the extremely important question of test track surface selection. Especially, the surface recently standardized by ISO for vehicle noise tests is compared to a surface more representative of actual road conditions. Other parameters considered include temperature, speed and microphone positions.Standardized measurement methods are necessary not only for classification of tires but also for classification of road surfaces. Therefore, the paper includes a status review of work going on in an ISO group which aims at standardizing a method for classification of the noise properties of road surfaces. Finally, it is emphasized that due to the many parties involved and the risk of working out too many and separate methods, it is absolutely necessary to co-ordinate the efforts internationally.
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- SITBON, F, et al.
(author)
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COMPARTMENTATION OF INDOLE-3-ACETIC-ACID METABOLISM IN PROTOPLASTS ISOLATED FROM LEAVES OF WILD-TYPE AND IAA-OVERPRODUCING TRANSGENIC TOBACCO PLANTS
- 1993
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In: Planta. - 0032-0935 .- 1432-2048. ; 191:2, s. 274-279
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Journal article (peer-reviewed)abstract
- Cellular compartmentation of indole-3-acetamide (IAM), indole-3-acetic acid (IAA), and [N-15(1)]IAA synthesised from [N-15(1)]tryptophan was monitored in protoplasts isolated from sterile wild-type tobacco SR1 plants, and in IAA-overproducing plants expressing the Agrobacterium tumefaciens T-DNA IAA genes iaaM and iaaH. Indole-3-acetamide was located exclusively in the cytosol of both iaaM and iaaM/iaaH protoplasts, being 75% lower than in iaaM protoplasts, presumably because of conversion into IAA by action of the iaaH-encoded hydrolase. The free-IAA level, however, was raised only 8% in iaaM/iaaH compared to iaaM protoplasts, whereas the level of IAA-conjugates was increased more than fivefold. For both genotypes, the location of IAA conjugates was restricted to the cytosol, while one-third of the free-IAA pool was present in chloroplasts. Transcription of the iaaM gene was increased by fusion to the strong cautiflower mosaic virus (CaMV) 35S promoter. Compared with the wildtype, this led to an 18-fold higher conversion of [N-15(1)]tryptophan to [N-15(1)]IAA, a three- to fourfold increase in free IAA, and a tenfold higher level of IAA conjugates in 35S-iaaM/iaaH protoplasts. Also in these genotypes, IAA conjugates were exclusively cytosolic. There was no major difference between transgenic and wildtype protoplasts in the proportion of chloroplastic to total cellular IAA, although the chloroplastic IAA and [N-15(1)]IAA pools in the transformant were threefold and eightfold higher, respectively. Since the IAM pool in transgenic plants is exclusively cytosolic, these findings suggest that the increased chloroplastic [N-15(1)]IAA pool in 35S-iaaM/iaaH protoplasts is synthesised in the cytosol but rapidly transported into the chloroplast. Furthermore, the presence of IAA in the chloroplast together with the exclusively cytosolic location of IAA conjugates, suggests the presence of two differentially subcellular pools of IAA. The first is located in the cytosol and mainly regulated by non-decarboxylative catabolism and conjugation (Sandberg et al. 1990, Planta 180, 562-568), whereas the second is located in the chloroplast and is seemingly not directly regulated inside the organelle by either of these two processes. The cytosolic IAA control mechanisms, however, also affect the chloroplastic pool size due to the rapid transport of IAA between the two compartments.
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