[Analysis and Health Risk Assessment of Cadmium and Arsenic in Japanese, Vietnamese, and Indonesian Rice].

Herein, we quantified the concentrations of cadmium (Cd) and arsenic (As) in 63 milled rice (Oryza sativa L.) cultivated in Japan, Vietnam, and Indonesia. We estimated the daily intake of Cd and As by adults and children consuming this rice by inductively coupled plasma-mass spectrometer (ICP-MS). Cd and As were detected in all milled rice samples. No significant differences were observed in Cd concentrations between Japanese (50th percentile concentration: 0.036 mg/kg), Vietnamese (0.035 mg/kg), and Indonesian rice (0.022 mg/kg). However, As concentrations in Vietnamese rice (50th percentile concentration: 0.142 mg/kg) were significantly higher than those in Japanese (0.101 mg/kg, p<0.001) and Indonesian rice (0.038 mg/kg, p<0.0001). Target hazard quotients (THQs) were then calculated to evaluate the non-carcinogenic health risk from ingestion of individual heavy metals (Cd and As) by rice consumption. Results revealed that THQs of individual heavy metals for Japanese, Vietnamese, and Indonesian adults and children consuming this rice were all less than one, suggesting that no health risk is associated with the intake of a single heavy metal via rice consumption.

Uptake of [3H]L-serine in rat brain synaptosomal fractions.

Accumulation of [3H]L-serine in crude synaptosomal fractions freshly prepared from rat brain has been found to be temperature-sensitive and to consist of both Na(+)-dependent and Na(+)-independent components. The accumulation of [3H]L-serine measured at submicromolar concentrations had a distinct substrate selectivity, different from the uptake of [3H]L-proline, [3H]L-glutamate and [3H]GABA. It was fully inhibited by L-glutamine, L-asparagine, L-cysteine, L-alanine, L-leucine, L-isoleucine, L-tyrosine, L-phenylalanine, L-threonine and by the synthetic marker for the large neutral amino acid transport systems 2-aminobicyclo[2,2,1]heptane-2-carboxylic acid, but not influenced by beta-alanine, taurine, glycine nor was it inhibited by the marker for the A system, L-2-methylamino isobutyric acid. D-Serine at 1 mM concentration produced no significant inhibition of the accumulation of 10 nM [3H]L-serine. We conclude that L-serine uptake observed in the present study is mediated by at least two distinct transport systems: a Na(+)-dependent one of lower affinity (K(m) in mM range) and a Na(+)-independent system of higher affinity (K(m) approximately 20-100 micro M). Characteristics of [3H]L-serine accumulation displayed at low substrate concentrations suggest that it was mediated neither by the typical 'A', nor by the 'large neutral', amino acid transport systems but predominantly by transporters belonging to the recently identified LAT (L-amino acid transporter) family.