Kazuhiro Matsushita

Neuronal maturation and N-acetyl-l-aspartic acid development in human fetal and child brains

The developmental changes in N-acetyl-L-aspartic acid (NAA) were assessed in human fetal and child brains by means of high resolution proton magnetic resonance spectroscopy (MRS). NAA was detected in the cerebral cortex and white matter of fetuses of 16 weeks gestation. NAA increased gradually from 24 weeks gestation and remarkably from 40 weeks gestation to 1 year of age. The developmental changes in tissue NAA in postnatal brains were found to be similar to those of NAA/Cr on clinical proton MRS. As the neuronal cell density in the cerebral cortex decreases with dendritic maturation, an increase in NAA with age may reflect the normal and abnormal development of axons, dendrites and synapses as well as neuronal soma.

Inhibition of flight in Periplaneta americana (Linn.) by a trehalase inhibitor, validoxylamine A

Abstract Male adults of Periplaneta americana were graded into three groups according to their flight activity; very active (continuous flight longer than 5 min), active (1–5 min) and inactive (shorter than 1 min). 1H-NMR analysis showed that approx. 30 mM trehalose was present in the haemolymph of each of the above categories of untreated cockroaches. After exhaustive flight, the haemolymph trehalose concentration in very active individuals decreased to 2.5 min. The trehalase activity of the flight muscle was inhibited about 70% and the haemolymph trehalose concentration increased to about 3 times the normal level without change in the other haemolymph components. Trehalose also accumulated in the tissues of the cockroaches injected with validoxylamine A. These observations suggest that validoxylamine A inhibits the muscle trehalase and prevents the use of trehalose as a source of energy for flight.

Assessment of the toxicity of linear alkylbenzene sulfonate and quaternary alkylammonium chloride by measuring 13C-glycerol in Dunaliella sp.

Abstract The toxic effects of linear alkylbenzenesulfonate (LAS) and quaternary alkylammonium chloride on Dunaliella sp. were studied by measuring 13 C-glycerol. 13 C-glycerol (five isomers of [1,2,1′- 13 C 1,2,3 ]-glycerol) was produced in Dunaliella sp. from 13 C-sodium bicarbonate added and the amounts of 13 C-glycerol was lowered quantitatively with increased concentration of surfactants. The ratio of glycerol to 13 C-glycerol was found to be about 45 : 55 by gas chromatographic/mass spectrometric analysis. The 24-h median effective concentration (EC50-24h) were 3.5 mg/l for LAS, 0.79 mg/1 for alkyltrimethyl-ammonium chloride (TM), 18 mg/l for dialkyldimethylammonium chloride (DM) and 1.3 mg/l for alkyldimethylbenzylammonium chloride (BM) : the toxic potencies were in the order of TM>BM>LAS>DM. The suppression of 13 C-glycerol formation by LAS seemed to be related to the process of photosynthesis from 13 C-sodium bicarbonate.

Decrease in cerebral free magnesium concentration following closed head injury and effects of VA-045 in rats

1. We examined the alterations in cerebral free Mg2+ concentration in closed head injury (CHI) in rats and the effects of VA-045, a novel apovincaminic acid derivative, on them with in vivo 31P-NMR. 2. Free Mg2+ decreased by about 30% within 20 min after head impact and, afterward, it gradually decreased further to reach about 60% of the control level after 3 hr. VA-045 inhibited the decrease. 3. In nonimpacted rats, VA-045 did not alter the free Mg2+ level. 4. The decrease in cerebral free Mg2+ following CHI may be a critical factor in the development of irreversible tissue injury, and VA-045 may prevent it.

Increased cerebral choline-compounds in Duchenne muscular dystrophy.

WE investigated the hypothesis that cell membrane function is abnormal in brains of subjects with Duchenne muscular dystrophy (DMD) using proton-nuclear magnetic resonance (NMR) spectroscopy of human brain extracts. The total amount of choline-containing compounds was significantly higher (about three times) than in normal controls and patients with other myopathies, while N-acetyl-L-aspartic acid and creatine were within the normal range. These findings indicate that abnormal cell membrane function may be correlated with the abnormal dystrophin or lack of dystrophin in the brain of patients with DMD.

Studies on uptake of cesium by mycelium of the mushroom ( Pleurotus ostreatus ) by133Cs-NMR

Sufficient information on the mechanisms of radiocesium translation from substrate to mushroom and long-term radiocesium accumulation is still not available, though high concentrations of radiocesium were reported in the fruiting bodies of various species of mushrooms especially after the Chernobyl accident. We studied the concentration and existing state of Cs in the cultured mycelium of the edible mushroom (Pleurotus ostreatus (Fr.) Kummer Y-1) using NMR. The133Cs NMR resulting spectra exhibited two resonance signals arising from the mycelium whereas one resonance signal from the external medium and CsCl standard solution. The chemical form of the signal in the downfield found in the only mycelium might be concerned with Cs accumulation in the mycelium.

Toxic effects of linear alkylbenzenesulfonate and quaternary alkylammonium chloride on Dunaliella sp. as measured by 1H-NMR analysis of glycerol

Abstract A new method to assess the toxic effects of linear alkylbenzenesulfonate (LAS : alkyl carbon number; 12) and quaternary alkylammonium chloride was established by using living green alga, Dunaliella sp.. This method is based on the 1 H-NMR determination of glycerol which decreased quantitatively with increased concentrations of surfactants. The flagella immobilities and the cell mortalities following the exposure of LAS and TM (alkyltrimethylammonium chloride : alkyl carbon number ; 16–18 ) increased with decreased glycerol contents. High correlations were found between the glycerol contents and the flagella immobilities, and the cell mortalities. No leakage of glycerol of which detection limit was 0.02 mM/L media into the media was detected. The EC 50-24h values of surfactants were 3.3 mg/L for LAS, 0.38 mg/L for TM, 18 mg/L for DM (dialkyldimethylammonium chloride : alkyl carbon number ; 16–18) and 1.8 mg/L for BM (alkyldimethylbenzylammonium chloride: alkyl carbon number; 12–14). The toxic potencies were in the order of TM>BM.LAS>DM.

13C and 31P NMR spectroscopic studies on glucose metabolism in Tribolium confusum

Nuclear magnetic resonance (NMR) technology was applied to study the glucose metabolism in Tribolium confusum (Coleoptera). 13C signals of D‐(1‐13C)glucose eaten by beetles were clearly detected in such metabolites of the glucose metabolism as glycogen, trehalose, triacylglycerol, alanine and proline by 13C‐NMR. After glucose feeding the 31P‐NMR spectra of T. confusum showed the signal intensity increases in arginine‐phosphate, sugar‐phosphate and uridine diphosphoglucose. The results demonstrated the potential of NMR analysis for the study of glucose metabolism in T. confusum.

PRODUCTION OF ETHANOL BY CULTURED INSECT CELLS

SummaryProton Nuclear Magnetic Resonance (1H-NMR) Analysis of insect cell culture media used for cultivating insect cell lines derived from the fleshflySarcophaga peregrina, swallowtail butterflyPapilio xuthus, and cabbage armywormMamestra brassicae revealed that ethanol appeared in the medium as the cultures aged. By incorporating [13C-1]-glucose into the media, we pursued13C-NMR spectrograms to show that the ethanol was derived from glucose. Thus, it became evident that the insect cells culturedin vitro produce ethanol from glucose as a metabolite.