A Simplified, Colorimetric Micromethod for Xylose in Serum or Urine, With Phloroglucinol

Clinical Chemistry (Impact Factor: 7.77). 09/1979; 25(8):1440-3.
Source: PubMed

ABSTRACT We have developed a simplified xylose assay procedure that requires only 10 min and requires 50 microL of serum or 5 microL of urine. The reaction with phloroglucinol is more sensitive than the classic p-bromaniline color reaction, and requires only 4 min of heating for color development. A single reagent is mixed with the specimen directly, without prior protein precipitation. Analytical recovery of xylose added to serum was quantitative; precision studies resulted in a between-day coefficient of variation of 5.2%. Glucose, which has significant potential for interference in most other xylose procedures, reacts under the test conditions only to the extent of 70 mumol of apparent xylose per liter for a 5.5 mmol/L solution of glucose. The new procedure has been valuable in the assessment of malabsorption, especially in children and infants, where serum xylose is the preferred measurement.

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    • "The birds with longer villi likely had increased nutrient absorption that could subsequently be linked to a lower feed intake. Study of gut absorption potential of the birds through transfer of an indicator sugar, such as d-xylose, from the upper small-intestinal tract to the blood (Eberts et al., 1979; Doerfler et al., 2000) could provide a deeper understanding to the examination of gut condition and specific rates of nutrient transfer in future studies. "
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    ABSTRACT: The effect of metabolic efficiency and associated gut characteristics of laying hens on the variability of transfer of dietary n-3 polyunsaturated fatty acids (PUFA) to the egg was examined in laying hens at 56 wk of age. An empirical energetics model was used to categorize individual hens into energetically efficient or nonefficient treatments based on residual maintenance ME requirement. Birds were then provided a diet containing an extruded flax product as a source of n-3 PUFA for 14 d. Egg traits were determined and yolks collected at 0 d and 14 d for measurement of fatty acid composition and variation in fatty acid levels within hen efficiency class. Gut length and duodenal histomorphometric indices were assessed after the 14-d experimental period. Efficient hens had a 96.01% rate of lay compared with 88.63% in nonefficient hens. After 14 d of feeding, the concentration of n-3 PUFA increased (151.6 vs. 315.8 mg/egg) in the egg yolk whereas n-6 PUFA, saturated fatty acids, and monounsaturated fatty acids were reduced (P < 0.001). Energetic efficiency had no additional effect on these measurements. However, egg yolks from efficient birds had less α-linolenic acid but more docosapentaenoic acid than nonefficient birds, suggesting a greater up-conversion of medium-chain (α-linolenic acid) to long-chain fatty acids (docosapentaenoic acid) in efficient birds. After 14 d, the CV for total n-3 PUFA in egg yolks from efficient hens was lower than that from nonefficient birds (11.1 vs. 21.4), indicating a more uniform level of enrichment. Furthermore, efficient hens had longer duodenal villi (P = 0.02), resulting in a greater absorptive villi surface area (0.13 mm(2)/villi) than in nonefficient birds (0.10 mm(2)/villi; P = 0.01). Increased uniformity of n-3 PUFA enrichment of table eggs could be possible through focus on metabolic efficiency and gut absorptive condition in laying hens.
    Poultry Science 04/2012; 91(4):888-98. DOI:10.3382/ps.2011-01661 · 1.67 Impact Factor
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    • "Xylose absorption test was carried out by the method of Eberts et al. (1979), modified by Goodwin et al. (1984a) "
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    ABSTRACT: The aim of the present study was to investigate the putative effects of dietary supplementation with green tea powder on growth performance, D-xylose absorption as well as serum-selected parameters of broiler chickens. Forty 21-day-old chickens were randomly allocated into four groups and fed with diets supplemented with 0% (control), 1%, 2%, or 4% green tea powder for 2 weeks. At the end of the experiment, D-xylose absorption test was performed on all birds on a 45-min basis for 135 min, and PCV as well as serum total protein, total cholesterol, LDL-c, HDL-c, triglycerides, iron, calcium, and phosphorus concentrations were assayed. Body weight, feed intake, and feed conver-sion ratio (FCR) were also recorded during the experiment. No significant differences were observed in plasma D-xylose concentrations, PCV, or serum parameters among different groups (p>0.05). Differences in body weight, feed intake, and FCR were insignificant as well. In conclusion, dietary supplementation with green tea powder for 2 weeks has no adverse effect on PCV, intestinal absorption of D-xylose, serum total protein, lipid profile, and mineral concentrations as well as performance parameters of broiler chickens.
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    • "The glucose concentration was determined using the Glucose (GO) Assay Kit (Sigma GAGO-20) per the manufacturer's guidelines . Xylose concentration was determined using the phloroglucinol assay (Eberts et al. 1979). Briefly, the color reagent of 0.5 g of phloroglucinol (Sigma), 100 ml of glacial acetic acid, and 10 ml of concentrated HCl was freshly prepared and kept in the dark. "
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    ABSTRACT: Though highly efficient at fermenting hexose sugars, Saccharomyces cerevisiae has limited ability to ferment five-carbon sugars. As a significant portion of sugars found in cellulosic biomass is the five-carbon sugar xylose, S. cerevisiae must be engineered to metabolize pentose sugars, commonly by the addition of exogenous genes from xylose fermenting fungi. However, these recombinant strains grow poorly on xylose and require further improvement through rational engineering or evolutionary adaptation. To identify unknown genes that contribute to improved xylose fermentation in these recombinant S. cerevisiae, we performed genome-wide synthetic interaction screens to identify deletion mutants that impact xylose utilization of strains expressing the xylose isomerase gene XYLA from Piromyces sp. E2 alone or with an additional copy of the endogenous xylulokinase gene XKS1. We also screened the deletion mutant array to identify mutants whose growth is affected by xylose. Our genetic network reveals that more than 80 nonessential genes from a diverse range of cellular processes impact xylose utilization. Surprisingly, we identified four genes, ALP1, ISC1, RPL20B, and BUD21, that when individually deleted improved xylose utilization of both S. cerevisiae S288C and CEN.PK strains. We further characterized BUD21 deletion mutant cells in batch fermentations and found that they produce ethanol even the absence of exogenous XYLA. We have demonstrated that the ability of laboratory strains of S. cerevisiae to utilize xylose as a sole carbon source is suppressed, which implies that S. cerevisiae may not require the addition of exogenous genes for efficient xylose fermentation.
    G3-Genes Genomes Genetics 09/2011; 1(4):247-58. DOI:10.1534/g3.111.000695 · 2.51 Impact Factor
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