A method for the sensitive and specific determination of folate derivatives was developed. The method involves hydrolysis by γ-glutamyl hydrolase and high-performance liquid chromatography with electrochemical detection. The method was applied to measure the change in the level of folate derivatives in the liver, kidney, spleen and brain of rats during folate deficiency. 5, 6, 7, 8-Tetrahydrofolic acid was the major folate derivative in the liver, kidney, spleen and brain. Total concentration of folate derivatives decreased from the second week of folate deficiency in the liver, kidney, spleen and brain followed by anemia, which ap-peared at the fifth week. The level of 5, 6, 7, 8-tetrahydrofolic acid in the brain did not change during folate deficiency, but it significantly decreased in the liver, kidney and spleen.

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With the availability of A-ring labelled 25OHD₂, [3α-³H] 25OHD₂, we have performed the present study to examine the metabolism of 25OHD₂ using physiological substrate concentrations in perfused kidneys isolated from both normal and vitamin D₂-intoxi-cated rats. Our results indicate that [3α-³H] 25OHD₂ is metabolized into both 24(S), 25, 28-trihydroxyvitamin D₂ [24(S), 25, 28(OH)₃D₂] and 24(R), 25, 26-trihydroxyvitamin D₂ [24(R), 25, 26(OH)₃D₂], and the amounts of these two metabolites produced in the kidney of vitamin D₂-intoxicated rat were about 3-5 times higher than those produced in the kidney of normal rat. Similar results were also obtained with rat kidney homogenates incubated with [3a-3H] 250HD2. Furthermore, we noted that the production of both 24(S), 25, 28(OH)₃D₂ and 24(R), 25, 26(OH)₃D₂ in the kidney homogenates of vitamin D₂-intoxicated rats increased with the time of incubation and then subsequently decreased. The decrease in both 24(5), 25, 28(OH)₃D₂ and 24(R), 25, 26(OH)₃D₂ coincided with an increase in the fraction of total radioactivity distributed in the aqueous phase of the kidney homogenates. This finding suggested the possibility of further metabolism of 24(S), 25, 28(OH)₃D₂ and 24(R), 25, 26(OH)₃D₂ into polar water-soluble metabolite(s). We then measured the radioactivity in the aqueous phase of kidney homogenates of both normal and vitamin D₂-intoxicated rats incubated with [3α-³H]25OHD₂. It was noted that the amount of radioactivity in the aqueous phase of kidney homogenates of vitamin D₂-intoxicated rats is higher than that present in the aqueous phase of kidney homogenates of normal rats. Thus, our study provides evi-dence for the first time for the formation of both 24(S), 25, 28(OH)₃D₂ and 24(R), 25, 26(OH)₃D₂ under physiological conditions, and the possibility of their further metabolism into as yet unidentified polar water-soluble metabolite(s). As the formation of all these metabolites is increased in the kidney of vitamin D2-intoxicated rats when compared to normal rats, it appears that the increased rate of metabolism of 25OHD₂ during hypervitaminosis D₂ plays a significant role in the deactivation of 25OHD₂.

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In vivo antioxidative effects of curcumin were investigated using a trichloroethylene (TCE)-induced oxidative stress model in mouse liver. Increases in the con-tents of peroxisome and thiobarbituric acid reactive substances (TBARS) and decreases in GSH content of mouse liver by the TCE administration were suppressed by the pre-adminis-tration of curcumin. TCE-induced changes in the activities of antioxidative enzyme, such as Cu/Zn-SOD, catalase, glutathione reductase, glutathione peroxidase (GPx) and D-glucose-6-phosphate dehydrogenase (G6PD), were also diminished by curcumin. These results indi-cate that curcumin significantly suppresses TCE-induced oxidative stress by scavenging var-ious free radicals, and its antioxidative activity seems to be derived from its suppressive ef-fects on the increase in peroxisome content and decrease in GPx and G 6PD activities.

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The present study describes the cholesterol absorption by hyperlipidemia ath-erosclerosis prone (LAP) Japanese quail to address their high susceptibility to experimental atherosclerosis. The apparent cholesterol absorption rate of LAP quail was compared with that ofcommercially available (CA) Japanese quail. After 14 d of cholesterol feeding by ga-vage, it was found that the cholesterol excretion of LAP quail was significantly lower than that of CA quail. The fecal excretion of bile acid and fat showed a similar tendency to that as shown with the case of cholesterol. The cholesterol feeding only increased the serum choles-terol level of LAP quail, and this trend holds true for the liver lipid concentration. The ex-pression level of liver cholesterol 7α-hydroxylase mRNA showed no difference between LAP and CA strains under the conditions of cholesterol loading. These results showed that the cholesterol absorption by LAP quail is significantly higher than that by CA quail, which may reasonably explain the higher susceptibility of this strain to experimental atherosclero-sis.

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The aim of this study is to investigate the influence of oxidized frying oil (OFO) on the induction of individual forms of cytochrome P450 (CYP450) in guinea pigs. The OFO samples were obtained by frying potato chips in soybean oil at 200±5°C for 24 h. Sixteen male weaning guinea pigs were fed for 12 wk on a diet which included 15% of ei-ther OFO or fresh soybean oil supplemented with 300 ppm ascorbic acid. It was demon-strated that guinea pigs fed with the OFO diet (D300) exhibited inferior growth rates and lower feed efficiency than the control group (F300). The vitamin C contents of plasma, liver, and kidney in the D300 group were lower than those in the F300 group. Further, the thio-barbituric acid-reactive substance content in D300 liver and kidney was higher than that in the F300 equivalent. The liver UDP-glucuronyl-transferase activity in the D300 group was higher than that in the F300 group, and there was no difference in comparing the glu-tathione-S-transferase activity levels of the two groups. Notably, the total CYP450 content and the NADPH-cytochrome c reductase activity were significantly elevated in the D300 group. The ethoxyresorufin 0-deethylase activity, which mainly represents CYP1A1 activ-ity, for the detection of CYP450 isozyme characteristics was elevated more in the D300 than in the F300 group. There was no difference in the pentoxyresorufin 0-dealkylase activity, which mainly reflects the CYP2P isozyme, between the two groups. However, the quantity of CYP1A1 isoform determined in the D300 group did not differ from that in the F300 group, as revealed by SDS-PAGE and western blot testing. Our results demonstrate that the relative enzyme activity to CYP1A1-like activity of the guinea pig hepatic xenobiotic metab-olizing enzyme system may be induced by OFO feeding, but more advanced research is needed to identify the predominant form of CYP450 isozyme induced as a result of this con-dition.

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Breast milk provides the essential nutrients for infants in readily available form. The content of nitrogen in human milk is of great importance because it relates to the growth of infants in the early stage, and the composition of nitrogenated compounds varies according to the lactational stage. Three-hundred-and-three human milk specimens were obtained from 240 healthy mothers living in two different districts in Taiwan, and 264 specimens were used for the analysis. The crude protein content, total and free amino acid compositions as well as urea content were evaluated using pooled milk samples according to different lactational stages and geographical location. The crude protein content de-creased sharply from colostrum (2.51g/100mL) to mature milk (1, 25g/100mL), Total amino acids account for 80-85% of the crude protein throughout the whole lactation pe-riod. Crude protein also contained 30 to 35mg/100mL urea and 41 to 48mg/100mL free amino acids as non-protein nitrogen components. The ratio of essential to non-essential amino acids remained constant throughout the lactation period in spite of a decline in amino acid content. The amino acid composition per 1 g of nitrogen varied during the lacta-tion period. The differences of these lactational changing patterns of individual amino acids were probably reflected by variation of the protein composition during lactation, The sum of free amino acid content ranged from 43 to 50mg/100mL in Taipei and 40 to 45mg/100mL in Kaohsiung. Although the variations of free amino acids during the lacta-tion period differed among amino acids, glutamic acid predominated in mature milk while phosphoethanolamine was predominant in colostrum.

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The effects of phospholipids (PLs) transesterified with polyunsaturated fatty acids (PUFAs) with lipase (Aspergillus niger) on gelatinization and retrogradation of starch during storage were studied by differential scanning calorimetry (DSC). The resulting trans-esterified PLs were rich in PUFAs and linoleic acid, while the total percentage of PUFAs in-corporated was 20.2%. The addition of PLs or PLs enzymatically transesterified with PUFAs (PUPA-PLs) to the starch sample decreased the gelatinization enthalpy of starch (Δh_g) slightly, but clearly increased the starch-lipid complexes (Δhs_-1) by DSC. After 21 days of storage, the percent of retrogradation of starch became lower by the addition of 4% PLs or 4% PUFA-PLs to the starch sample when compared with the control. These results suggest that PLs retard retrogradation of starch during storage, whereas PUFA-PLs retard it greatly. The addition of PLs or PUFA-PLs increased the amount of Δhs_-1, while re-gelatinization en-thalpy decreased during storage, which suggests that PLs or PUFA-PLs could retard the ret-rogradation of starch.

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We describe a method for the simultaneous assay of retinol and a-tocopherol using normal-phase, high-performance liquid chromatography (HPLC). Our normal-phase HPLC method gave better resolution (Rs) of retinol (Rs=1.58) and α-tocopherol (Rs=1.40) when compared with the Rs values for a-tocopherol and retinol from literature. Also, the α-tocopherol concentrations obtained by our method agreed well with another normal-phase HPLC method that used fluorometric detection (r=0.951, p<0.001, Sy.x=0.58mg/L). The concentrations of retinol in our method agreed well with those determined by a reversed-phase HPLC procedure, although the correlation (r=0.646, p<0, 001, Sy.x=62, μg/L) was not as good as the method proposed. Our procedure gave acceptable precision; the within-run CV was 7.7% for α-tocopherol and 5.9% for retinol. The between-day CV was 9.0% for α-tocopherol and 6.8% for retinol. The mean recoveries were 97% for a-tocopherol and 107% for retinol. Our assays were linear for α-tocopherol concentrations from 0.1 to 30mg/L and for retinol concentrations from 20 to 2, 000μg/L. In children ages 7 to 12 y, and in adolescents ages 14 to 16 y, the α-tocopherol and retinol concentrations in the blood were significantly lower than the concentrations in normal adults. Individuals over 70 y old also showed α-tocopherol and retinol values that were lower than those of normal adults between ages 30 and 40 y In female university students, the inter-individual variation of α-tocopherol was reduced by dividing the α-tocopherol results by their total cholesterol or total lipid concentrations; however, this was not obtained for retinol. In cancer patients undergoing surgery, the ratio of retinol to retinol-binding protein (RBP) remained fairly con-stant, although the concentrations of both retinol and RBP decreased to about one-half the preoperative values after surgery. We conclude that our normal-phase HPLC method is a stable and reproducible method for α-tocopherol and retinol, and is an easy-to-use analytical tool.

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We measured retinol levels and β-carotene 15, 15'-dioxygenase activity in rats with streptozotocin-induced diabetes mellitus to assess the relationship between the dis-ease and the conversion of β-carotene to retinol. The plasma retinol level was significantly lower in diabetic rats than in control rats, but the hepatic retinol level was significantly higher than the control. The hepatic dioxygenase activity, but not that of the intestinal mu-cosa, was significantly lower in diabetic rats than in control rats. The hepatic dioxygenase activity showed a significant negative correlation with the hepatic retinol levels. The results suggest the disturbed secretion of retinol from the liver and suppression of hepatic dioxy-genase activity by the retinol increased in the liver in diabetic rats.

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The proton relaxation behavior of dietary fibers on ₁H-NMR was investigated with water systems before and after heat treatment at 85°C for 30 min. Quite similar spin-spin relaxation curves were observed for dietary fibers except agar with or without heat treatment in the water system. The relaxation times for the fast and slow components and proton populations for the two components were analyzed to evaluate interaction between dietary fiber and water more precisely. As a result, it turned out that there was little varia-tion in the relaxation time and the proton population before and after heat treatment as well. Therefore, most dietary fibers were inferred to be heat-stable in respect of proton ex-change for water.

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