phosphorus-radioisotopes and alpha-glycerophosphoric-acid

Using phosphorous-31 nuclear magnetic resonance (31P-NMR) spectroscopy, we observed the metabolic kinetics of organophosphate compounds in the rat lens during cataract development induced by different doses of galactose (5%, 15%, 25%, and 40%) added to rat chow. The metabolic and histologic changes in the lenses were compared among the rats fed with different doses of galactose. alpha-Glycerophosphate significantly increased in response to the galactose doses, followed by a decrease to steady values of approximately 120% of the base line value, except in the 40% galactose group, which had a marked decrease to 68% of the base line value. Choline phosphate decreased rapidly during dosing in all but the 5% group, but no changes in those levels were observed after 2 weeks of galactose dosing. ATP decreased significantly when the histologic destruction progressed in the entire lens. Although inorganic phosphate increased significantly in a dose-dependent manner, it did not exceed the peak level. The histologic changes were closely related to the dynamic changes in the phosphorous compounds in the rat lens during formation of the galactose-induced cataract. Our results indicated that the development of a galactose-induced cataract was associated with the metabolic changes of the phosphate compounds.

Topics: Adenosine Triphosphate; Animals; Cataract; Galactose; Glycerophosphates; Histocytochemistry; Lens, Crystalline; Magnetic Resonance Spectroscopy; Male; Phosphates; Phosphorus Radioisotopes; Phosphorylcholine; Rats; Rats, Wistar

To determine what biochemical changes may occur in the brain in Williams syndrome (WS) and whether these changes may be related to the cognitive deficits.. WS is a rare, congenital disorder with a characteristic physical, linguistic, and behavioral phenotype with known cognitive deficits.. We obtained 31P magnetic resonance spectra (MRS) from a region consisting of mostly frontal and parietal lobe of 14 patients with WS (age, 8 to 37 years) and 48 similarly-aged controls. 1H MRS (27 cm3) localized to the left cerebellum obtained from the WS cohort were compared with those from 16 chronological age- and sex-matched normal controls. A battery of cognitive tests were administered to all subjects undergoing 1H MRS.. WS brains exhibited significant biochemical abnormalities. All 31P MRS ratios containing the phosphomonoester (PME) peak were significantly altered in WS, suggesting that PME is significantly decreased. Ratios of choline-containing compounds and creatine-containing compounds to N-acetylaspartate (Cho/NA and Cre/NA) were significantly elevated in the cerebellum in WS cf. controls, whereas the ratio of Cho/Cre was not altered. This suggests a decrease in the neuronal marker N-acetylaspartate in the cerebellum. Significant correlations were found between the cerebellar ratios Cho/NA and Cre/NA and the ability of all subjects at various neuropsychological tests, including Verbal and Performance IQ, British Picture Vocabulary Scale, Ravens Progressive Matrices, and Inspection Time.. The correlations can be interpreted in two ways: 1) Our sampling of cerebellar biochemistry reflects a measure of "global" cerebral biochemistry and is unrelated to cerebellar function, or 2) The relations indicate that cerebellar neuronal integrity is a requirement (on a developmental time scale or in real-time) for ability on a variety of cognitive tests.

Topics: Adenosine Triphosphate; Adolescent; Adult; Brain Chemistry; Cerebellum; Child; Cognition; Ethanolamines; Female; Frontal Lobe; Glycerophosphates; Hexosephosphates; Humans; Inositol Phosphates; Magnetic Resonance Spectroscopy; Male; Neuropsychological Tests; Parietal Lobe; Phosphocreatine; Phosphorus Radioisotopes; Phosphorylcholine; Phosphoserine; Protons; Radionuclide Imaging; Williams Syndrome

Studies with Escherichia coli cells showed that the transport systems encoded by glpT (sn-glycerol 3-phosphate transport) and uhpT (hexose phosphate transport) catalyze a reversible 32Pi:Pi exchange. This reaction could be used to monitor the glpT or uhpT activities during reconstitution. Membranes from suitably constructed strains were extracted with octylglucoside in the presence of lipid and glycerol, and proteoliposomes were formed by dilution in 0.1 M KPi (pH 7). Both reconstituted systems mediated a 32Pi:Pi exchange which was blocked by the appropriate heterologous substrate, sn-glycerol 3-phosphate (G3P) or 2-deoxyglucose 6-phosphate (2DG6P), with an apparent Ki near 50 microM. In the absence of an imposed cation-motive gradient, Pi-loaded proteoliposomes also transported the expected physiological substrate; Michaelis constants for the transport of G3P or 2DG6P were near 20 microM. The heterologous exchange showed a maximal velocity of 130 nmol/min/mg protein via the glpT system and 11 nmol/min/mg protein for the uhpT system. This difference was expected because the G3P transport activity had been reconstituted from a strain carrying multiple copies of the glpT gene. Taken together, these results suggest that anion exchange may be the molecular basis for transport by the glpT and uhpT proteins.

Topics: Anions; Biological Transport; Carrier Proteins; Cell Membrane; Escherichia coli; Escherichia coli Proteins; Glucose-6-Phosphate; Glucosephosphates; Glycerophosphates; Hexosephosphates; Liposomes; Phosphates; Phosphorus Radioisotopes