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Quantification of hepatic transaldolase exchange activity and its effects on tr...
Jones, John G.; Garcia, Paula; Barosa, Cristina; Delgado, Teresa C.; Caldeira, M. Madalena; Diogo, LuisaExchange of hepatic glucose-6-phosphate (G6P) and glyceraldehyde-3-phosphate via transaldolase modifies hepatic G6P enrichment from glucose or gluconeogenic tracers. Transaldolase exchange was quantified in five healthy, fed subjects following an oral bolus of [1,2,3-13C3]glycerol (25-30 mg/kg) and paracetamol (10-12 mg/kg). 13C Isotopomers of hepatic G6P were quantified by 13C NMR spectroscopy of urinary glucu...
Hepatic UDP-glucose 13C isotopomers from [U-13C]glucose: A simple analysis by 1...
Mendes, Ana C.; Caldeira, M. Madalena; Silva, Cláudia; Burgess, Shawn C.; Merritt, Matthew E.; Gomes, Filipe; Barosa, Cristina; Delgado, Teresa C.Menthol glucuronide was isolated from the urine of a healthy 70-kg female subject following ingestion of 400 mg of peppermint oil and 6 g of 99% [U-13C]glucose. Glucuronide 13C-excess enrichment levels were 4-6% and thus provided high signal-to-noise ratios (SNRs) for confident assignment of 13C-13C spin-coupled multiplet components within each 13C resonance by 13C NMR. The [U-13C]glucuronide isotopomer derived...
Noninvasive analysis of hepatic glycogen kinetics before and after breakfast wi...
Jones, John G.; Fagulha, Ana; Barosa, Cristina; Bastos, Margarida; Barros, Luisa; Baptista, Carla; Caldeira, M. Madalena; Carvalheiro, ManuelaThe contributions of hepatic glycogenolysis to fasting glucose production and direct pathway to hepatic glycogen synthesis were quantified in eight type 1 diabetic patients and nine healthy control subjects by ingestion of (2)H(2)O and acetaminophen before breakfast followed by analysis of urinary water and acetaminophen glucuronide. After overnight fasting, enrichment of glucuronide position 5 relative to body...
Simple measurement of gluconeogenesis by direct 2H NMR analysis of menthol gluc...
Ribeiro, Angela; Caldeira, M. Madalena; Carvalheiro, Manuela; Bastos, Margarida; Baptista, Carla; Fagulha, Ana; Barros, Luisa; Barosa, CristinaThe contribution of gluconeogenesis to fasting glucose production was determined by a simple measurement of urinary menthol glucuronide (MG) 2H enrichment from 2H2O. Following ingestion of 2H2O (0.5% body water) during an overnight fast and a pharmacological dose (400 mg) of a commercial peppermint oil preparation the next morning, 364 mumol MG was quantitatively recovered from a 2-h urine collection by ether e...
A multinuclear NMR study of the complexation of W(VI) with meso-2,3-dimercaptos...
Caldeira, M. Madalena; Ramos, M. Luísa; Pereira, Gilberto G.; Gil, Victor M. S.Meso-2,3-dimercaptosuccinic acid (DMSA), which is used as an antidote for heavy metal poisoning and in complexes of 99mTc for diagnostic purposes, forms several complexes with tungsten(VI) in aqueous solutions, as found by 1H, 13C, 17O and 183W NMR spectroscopy. In the pH range ~4-7, there are four complexes in which the acid acts as a bidentate ligand through one carboxyl group and the adjacent sulfhydryl grou...
Peroxovanadium(V) complexes of glycolic acid as studied by NMR spectroscopy
Justino, Licínia L. G.; Ramos, M. Luísa; Caldeira, M. Madalena; Gil, Victor M. S.Multinuclear (1H, 13C, 17O, 51V) 1D and 2D NMR spectroscopy has been used to characterize the peroxovanadium(V) complexes of glycolic acid in aqueous solution. One 2:2:2 (metal:ligand:peroxo) complex, together with a 1:1:1 and a 2:2:1 species, are found in the pH range 1-7. The 2:2:2 complex is a monoperoxo (one peroxide unit per vanadium atom) dinuclear species having a V2O3 4+ seven-coordinated metal centre. ...
Peroxovanadium(V) Complexes of L-Lactic Acid as Studied by NMR Spectroscopy
Justino, Licínia L. G.; Ramos, M. Luísa; Caldeira, M. Madalena; Gil, Victor M. S.A multinuclear (1H, 13C, 17O, 51V) 1D and 2D NMR study of the complexation of l-lactic acid with vanadium(V) and hydrogen peroxide shows that four peroxo complexes are formed in aqueous solution in the pH range 1-7. Two isomeric 2:2:1 (metal:ligand:peroxo) complexes, together with a 2:2:2 species, are found over the entire pH range. At pH values below 2 an additional 1:1:1 complex is formed. The acid was found ...
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