A report of accidental ethylene glycol ingestion in 2 siblings.

We describe a case of 2 siblings aged 2 1/2 and 3 1/2 yrs accidentally poisoned by ethylene glycol ingestion. We found estimating the level of ethylene glycol in plasma by calculation of osmolar gap too insensitive to be of value and advocate the availability of a specific method. In our study only one of the 2 children had a toxic level of ethylene glycol but assay by conventional assay and by proton magnetic resonance spectroscopy (1HMRS) of toxic metabolites viz glycolate, glyoxylate and oxalate showed both to be excreting grossly elevated levels. This indicates the desirability of assaying the toxic metabolites of the glycol as well as the parent compound in assessing ingestions.

Application of high field localised in vivo 1H MRS to study biochemical changes in the thiamin deficient rat brain under glucose load.

In vivo, volume-selected 1H NMR spectroscopy employing the SPACE technique was used to monitor biochemical changes in the thiamin deficient rat brain in response to glucose loading. The concentrations of brain N-acetylaspartate, glutamate/glutamine/gamma-aminobutyric acid, lactate and glucose differed significantly from those of control animals. The results are consistent with a metabolic block at the reaction catalyzed by the thiamin dependent enzyme alpha-keto glutarate dehydrogenase soon after the onset of neurological symptoms of thiamin deficiency, and a further block at pyruvate dehydrogenase arising late in the course of thiamin deficiency.

Measurement of the T2 relaxation time of ethanol and cerebral metabolites, in vivo.

The SPACE volume selection technique was combined with a spin-echo sequence to measure the transverse relaxation time of the resonances of ethanol and cerebral metabolites in the dog brain, in vivo. The method was extended to measure brain metabolite T2 values in the rat using 1H NMR microspectroscopy. The T2 decays for the resonances of the metabolites N-acetylaspartate, creatine/phosphocreatine, and choline/phosphorylcholine were found to be biexponential with long T2 components of 490, 260, and 350 ms for the dog and 490, 220, and 355 ms for the rat brain, respectively. The existence of a second T2 component may originate from J-coupled nonresolved metabolite resonances. The relaxation decay for the ethanol triplet could be fitted to a single exponential giving a T2 relaxation time of 335 ms. However, given the large errors in the measurement of ethanol peak intensities at short echo times because of overlapping lipid signal and the effects of J-modulation, a biexponential decay with a long T2 component of 335 ms cannot be ruled out. Ambiguities regarding the reported partial detection of the 1H NMR signal of ethanol in the brain are discussed.

The visibility of the 1H NMR signal of ethanol in the dog brain.

In vivo, high-resolution, volume-selected 1H NMR spectroscopy was used to monitor the concentration of ethanol in the dog brain following intravenous injection of ethanol. Equilibration of ethanol in the body water should result in approximately equivalent concentrations of ethanol in the blood and brain. However, the mean equilibrium brain ethanol concentration determined using N-acetylaspartate as an internal standard was only 23 +/- 5% of the blood ethanol concentration. The disparity between blood and brain ethanol concentrations was attributed to underestimation of the ethanol concentration due to overlapping resonances with NAA and to T2 attenuation or possible nondetection of the 1H signal from ethanol bound at the surface of cell membranes and partitioned into the hydrophobic core of membrane lipids.

In vivo volume-selective metabolite editing via correlated z-order.

Volume-selected 1H NMR spectroscopy was combined with spectral editing to selectively detect brain metabolites. The SPACE localization sequence was used to create a voxel of zeta-magnetization which could then be edited for any scalar coupled metabolite by the use of selective excitation in the ECZOTIC sequence to generate longitudinal spin order. The sequence returns an edited signal with no intrinsic loss of magnetization. The method was applied to observe approximately 10 mM ethanol and 17 mM lactate in the brain of a dog.

The 1H NMR visibility of intracellular lactate in Streptococcus faecalis.

1H NMR studies of glycolysis in washed cell suspensions of Streptococcus faecalis indicated that intracellular lactate is not 1H NMR visible. Evidence for this was gained from time course studies of glycolysis at increasing concentrations of glucose. A close correlation existed between the relative increase in the lactate integral and the enzymatically determined extracellular lactate concentration [Lo]. When ionophores which cause the collapse of the positive intracellular/extracellular lactate gradient were added to cell suspensions following fermentation of 5, 10 and 50 mM glucose, the increase in the lactate integral was proportional to the respective increase in [Lo]. A more direct method for determining the origin of the lactate signal involved centrifugation of a cell suspension after fermentation of 50 mM glucose and measurement of lactate in the extracellular and intracellular fluid. 1H spectra of the cell suspension, supernatant and sonicated pellet revealed that the lactate observed in the cell suspension was equivalent to the lactate in the supernatant alone. The intracellular lactate contained in the pellet represented 42% of the total lactate, indicating that only 58% of lactate is detected by in vivo 1H MRS of S. faecalis. This result is in contrast with the high percentage (70-90%) of in vitro lactate which is detected by in vivo 1H MRS of mammalian brain tissue (Williams S. R. et al. Magn. Res. Med. 7, 425-431, 1988). This may be due to a higher proportion of extracellular lactate in mammalian tissue or differences in the intracellular environments of bacterial and mammalian cells.

Water suppression with B0 field gradient homospoil pulses in high-resolution NMR spectroscopy.

The combination of a frequency nonselective excitation suppression method (1331 sequence) with selective excitation followed by gradient-induced dephasing of water transverse magnetization yielded suppression ratios of greater than 10,000:1. The need for gradient preemphasis and correction of B0 field shifts is discussed. The suppression efficiency of this method compared favorably to results obtained using the CPMG spin-echo technique to observe metabolite resonances in a urine sample.

The unequivocal determination of lactic acid using a one-dimensional zero-quantum coherence-transfer technique.

A method based on zero-quantum coherence transfer for spectral editing of metabolites in aqueous solution in a one-dimensional experiment is described. Water suppression factors of approximately 8000 were achieved by the use of pulsed B0 field gradients and excellent editing was obtained in a single acquisition. The methyl resonances of both lactate and acetaldehyde were readily observed in a mouse brain homogenate by generating zero-quantum coherence using Gaussian pulses for selective excitation of the respective CH resonances.

Lung carbonyl reductase in the mouse: biochemical and catalytic properties.

Two major forms of aldehyde reductase (AHR) activity were resolved following zone electrophoresis of mouse lung homogenates and distinguished by their differential substrate and inhibitor specificities: alcohol dehydrogenase (ADH) C2 and carbonyl reductase (CBR). CBR was purified to homogeneity by DEAE-cellulose chromatography, affinity chromatography using Blue-sepharose, followed by gel filtration on Sephacryl S-200. The enzyme exhibited a native MW of 122,000, comprising 4 identical subunits. Kinetic and inhibition characteristics resembled those reported by Nakayama and coworkers (1982) for guinea pig lung CBR. Mouse lung CBR exhibited optimal activity at pH 5.0; a preference for NADPH as coenzyme, although reactive with NADH at an order of magnitude higher concentration; poor activity as an ADH, but was strongly inhibited by 4-methyl pyrazole; and was inhibited by quercitin, dithiothreitol and p-OH-mercuribenzoate, but was insensitive to valproate or sorbinil. These properties, coupled with the activity of CBR with a range of aliphatic and aromatic aldehydes, ketones and quinones, distinguish it from other AHRs. The unique localization in lung tissue suggests a possible role for CBR in the detoxification of xenobiotics and of toxic aldehydes derived from lipid peroxidation processes.

In vitro metabolism of [2-13C]-ethanol by 1H NMR spectroscopy using 13C decoupling with the reverse dept polarization-transfer pulse sequence.

The metabolism of [2-13C]-ethanol by alcohol dehydrogenase purified from Drosophila melanogaster has been observed by proton nuclear magnetic resonance spectroscopy (NMR). The reverse-DEPT pulse sequence, with composite pulse 13C decoupling to simplify and increase the signal-to-noise of spectra, has been used to eliminate the strong water signal while still observing the proton signals of metabolites of interest. Using these techniques the rates of synthesis of acetaldehyde, its diol and acetate from [2-13C] ethanol by alcohol dehydrogenase were measured simultaneously.

Genetic variability of alcohol dehydrogenase among Australian Drosophila species: correlation of ADH biochemical phenotype with ethanol resource utilization.

Alcohol dehydrogenase (ADH) activities, electrophoretic phenotypes, and the extent of ethanol resource utilization are compared for three groups of species distinguishable on ecological criteria: 1) the cosmopolitan species D. melanogaster, a frequent inhabitant of wineries; 2) fruit-baited species of the typically Australian subgenus Scaptodrosophila: D. lativittata, D. nitidithorax and D. howensis; and 3) Scaptodrosophila species not attracted to fermented-fruit baits being collected by sweeping in temperate rain forests (D. inornata, D. collessi) or from Hibiscus flowers (D. hibisci). D. melanogaster showed the highest levels of ADH activity and an electrophoretic polymorphism with two active allelic forms, while group 2) species showed intermediate ADH activities and polymorphisms, which were consistent with "high activity" and "low activity" allelic forms in natural populations of these species, and group 3) species showed only "low activity" forms. Ethanol resource utilization follows the same sequence, being 1 greater than 2 greater than 3 (D. howensis and D. collessi were not tested). Therefore the species considered show an association of ADH biochemical phenotype, laboratory ethanol utilization, and resources utilized.