Determination of the Catalytic Groups of Intestinal Brush-Border Sucrase by pH-Variation Studies

1979 ◽  
Vol 7 (5) ◽  
pp. 1071-1072 ◽  
Author(s):  
CHARLES TELLIER ◽  
NICOLE BERTRAND-TRIADOU ◽  
FRANCISCO ALVARADO
Keyword(s):  
Brush Border ◽  
Ph Variation ◽  
Intestinal Brush Border

scholarly journals Determination of unidirectional uptake rates for lipids across the intestinal brush border

1972 ◽  
Vol 13 (2) ◽  
pp. 184-192
Author(s):  
Verney L. Sallee ◽  
Frederick A. Wilson ◽  
John M. Dietschy
Keyword(s):  
Brush Border ◽  
Intestinal Brush Border ◽  
Uptake Rates

Quantitative Analysis of 5-Hydroxymethylfurfural in Linezolid Injection by High Performance Liquid Chromatography

2020 ◽  
Vol 16 (8) ◽  
pp. 1059-1067
Author(s):  
Jéssica Maurício Batista ◽  
Christian Fernandes
Keyword(s):  
High Performance ◽  
Potassium Phosphate ◽  
Gradient Elution ◽  
High Performance Liquid Chromatographic ◽  
Official Method ◽  
Ph Variation ◽  
Drug Products ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic

Background: Linezolid is a synthetic broad-spectrum antibacterial belonging to the class of oxazolidinones. Linezolid for intravenous infusion is isotonized with dextrose. In acidic environment, the dehydration of dextrose produces furan derivatives, 5-hydroxymethylfurfural (5-HMF) being the main one. The determination of this degradation product is of fundamental importance, since there is evidence it is cytotoxic, genotoxic, mutagenic and carcinogenic. However, there is no official method for the determination of 5-HMF in drug products. Objective: The aim of this study was to develop and validate a high performance liquid chromatographic method to quantify 5-HMF in injection of linezolid. Methods: The chromatographic separation, after optimization, was performed on C18 (150 x 4.6 mm, 5 μm) column. Mobile phase was composed of 14 mM potassium phosphate buffer pH 3.0 ([H+] = 1.0 x 10-3) and methanol in gradient elution at 1.0 mL min-1. The injection volume was 10 μL and detection was performed at 285 nm. Results: The method was optimized and validated, showing selectivity, linearity in the range from 0.075 to 9.0 μg mL-1, precision (RSD ≤ 2.0%), accuracy (mean recovery of 100.07%) and robustness for temperature and pH variation. Conclusion: The method was shown to be adequate to determine 5-HMF in injection containing linezolid in routine analysis.

Divalent cations and vitamin B12 uptake by intestinal brush-border membrane vesicles

1980 ◽  
Vol 239 (6) ◽  
pp. G452-G456
Author(s):  
R. C. Beesley ◽  
C. D. Bacheller
Keyword(s):  
Vitamin B12 ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Divalent Cations ◽  
Intrinsic Factor ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Tetraacetic Acid ◽  
Intestinal Brush Border Membrane ◽  
Intestinal Brush Border

Brush-border membrane vesicles from hamster intestine were employed to investigate uptake (binding) of vitamin B12 (B12). Ileal vesicles took up 25 times more B12 than did jejunal vesicles. Uptake of B12 by ileal vesicles was dependent on intrinsic factor (IF) and required Ca2+. Increasing the Ca2+ concentration caused an increase in uptake of B12 reaching a maximum at approximately 8 mM Ca2+. At high Ca2+ concentrations, 6–8 mM, Mg2+ had little effect on uptake of B12. At low Ca2+ concentrations, up to 2 mM, Mg2+ stimulated B12 uptake. Mg2+, Mn2+, and, to a lesser extent, Sr2+ stimulated Ca2+-dependent B12 uptake, but Zn2+, Ba2+, Na+, K+, and La3+ did not. B12 was apparently not metabolized and was bound as IF-B12 complex, which could be removed with (ethylenedinitrilo)tetraacetic acid (EDTA). Our results suggest that two types of divalent cation reactive sites are involved in binding of IF-B12. One is Ca2+ specific. The other is less specific reacting with Mg2+, Mn2+, Sr2+, and perhaps Ca2+ itself, thereby stimulating Ca2+-dependent binding of IF-B12 to its ileal receptor.

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