Safety assessment of transgenic potatoes with soybean glycinin by feeding studies in rats.

Feeding studies of transgenic potatoes with native and designed soybean glycinins in rats were done for four weeks. The designed glycinin has four additional methioninyl residues in the middle of the glycinin molecule. Rats were divided into four groups fed (I) only a commercial diet, (II) the diet plus non-transgenic potatoes, (III) the diet plus transgenic potatoes with native glycinin, and (IV) the diet plus transgenic potatoes with designed glycinin. Rats were fed 2,000 mg/kg-weight potatoes every day by oral administration. During the period tested, rats in each group (groups II, III, and IV) grew well without marked differences in appearance, food intake, body weight, or in cumulative body weight gain. No significant differences were also found in blood count, blood composition, and in internal organ weights among the rats after feeding potatoes (groups II, III, and IV) for four weeks. Necropsy at the end of experiment indicated neither pathologic symptoms in all rats tested nor histopathological abnormalities in liver and kidney. Judging from these results, the transgenic potatoes with glycinins are confirmed to have nearly the same nutritional and biochemical characteristics as non-transgenic one.

A case of acquired zinc deficiency in a mature breast-fed infant.

We describe a 5-month-old Japanese infant with zinc deficiency, who was exclusively breast-fed and showed improvement after zinc supplement was administered. His serum zinc level and the zinc content of breast milk from his mother were extremely low, although the mother's serum zinc level was within normal limits. Zinc deficiency would not be latently uncommon in a mature breast-fed infant.

[Two cases of acute disseminated encephalomyelitis with lesions in the thalamus or basal ganglia on MRI].

Lesions in the thalamus or basal ganglia have rarely been reported in acute disseminated encephalomyelitis (ADEM). We experienced 2 cases of ADEM, in which MRI showed lesions in the thalamus or basal ganglia. Case 1, a 4-year-old boy, had gait disturbance, hyperesthesia and hyperreflexia. MRI (T2 weighted image) showed multiple high intensity areas in the right frontal lobe, bilateral parietal lobes and bilateral thalami. Case 2, a 4-year-old girl, complained of gait disturbance following a febrile episode, and displayed hyperreflexia. Several days later, she had visual disturbance of the left eye. MRI (T2 weighted image) revealed multiple high intensity areas in the dentate nucleus of left cerebellum, left occipital lobe, bilateral caudate nuclei, and the anterior part of bilateral lenticular nuclei. In both cases, CT could not demonstrate these lesions. Both of them were treated with corticosteroid and recovered rapidly. They had no recurrence. MRI is useful in diagnosis and follow-up of ADEM and may reveal lesions other than cerebral or cerebellar white matters.

Cardiolipin molecular species in rat heart mitochondria are sensitive to essential fatty acid-deficient dietary lipids.

Feeding various dietary lipids did not alter the mass of phospholipids in rat heart mitochondria, but the phospholipids' fatty acid compositions changed. Although the compositional changes in mitochondrial phosphatidylcholine and phosphatidylethanolamine were negligible, linoleic acid [cis 18:2(n-6)] of cardiolipin was replaced by other fatty acids from dietary lipids. An analysis of the molecular species showed an even greater extent of change than was observed by fatty acid composition analysis. The quantity of 18:2(n-6)/18:2(n-6) molecular species [18:2(n-6) in C-1 position/18:2(n-6) in C-2 position] in cardiolipin decreased when rats were fed lipids that were depleted of an essential fatty acid but not deficient in essential fatty aids (eicosatrienoic acid did not appear). The decrease in 18:2(n-6)/18:2(n-6) species in cardiolipin was most pronounced in rats fed sardine oil, in which the ratio of (n-3) to (n-6) polyunsaturated fatty acids was 0.2. The O2 consumption rate of rat heart mitochondria decreased as the quantity of 18:2 (n-6)/18:2(n-6) cardiolipin species decreased.

Mitochondrial function in rats is affected by modification of membrane phospholipids with dietary sardine oil.

Phospholipids of heart and liver of rats fed a diet containing sardine oil had more omega 3 polyunsaturated fatty acids and less omega 6 polyunsaturated fatty acids than those of rats fed corn oil, whereas there was little difference in the fatty acid composition of brain phospholipids. The mass of phospholipid classes in rat heart mitochondria was not changed, but their fatty acid compositions were altered. Modification of the fatty acid compositions of mitochondrial phosphatidylcholine and phosphatidylethanolamine reached a plateau after 10 d of feeding, but that of cardiolipin continued for 30 d. The O2 consumption rate of rat heart mitochondria decreased as the fatty acid composition of the phospholipids changed. This may be due to the reduction of the activity of cytochrome c oxidase, which requires cardiolipin for its activity. However, F1F0-ATPase, which also requires cardiolipin, was activated under the same conditions.

Distribution of phospholipid molecular species containing arachidonic acid and cholesterol in V79-UF cells.

V79-UF cells were isolated from Chinese hamster V79 cells as a cell line that requires exogenous unsaturated fatty acids for growth. V79-UF cells incorporated arachidonic acid into phospholipids. The molecular species of diacyl phosphatidylcholine and phosphatidylethanolamine containing arachidonic acid comprised 61.4 and 70.5% of the total phospholipid molecular species in total membranes and 58.1 and 64.7% in plasma membrane, respectively. Polyunsaturated molecular species were distributed in a higher amount in the intracellular membranes than in the plasma membrane. No significant difference was seen in the diffusion coefficient between the plasma membranes from cells supplemented with oleic and arachidonic acids in spite of a distinct difference in the degree of unsaturation between the molecular species of these plasma membranes. The amount of cholesterol in the plasma membrane was higher in the cells grown in the presence of arachidonic acid than in those grown in the presence of oleic acid.

Monoenoic fatty acid requirement in V79 cells.

When lipids were removed from the culture medium, growth of V79 cells ceased. Supplementation with cis-octadecenoic acids satisfied the requirement for lipids by V79 cells. After starvation of the exogenous lipids by the shift-down of the medium to lipid-free medium, the content of octadecenoic acid in phospholipids increased more slowly in V79 cells than in V79-R cells, which can grow in the lipid-starved medium. The incorporation of [14C]acetic acid into monoenoic fatty acids and phospholipid molecular species containing monoenoic fatty acids in V79 cells was lower than that in V79-R cells. The reduced formation of monoenoic fatty acids was shown to be due to deficiency in the stimulation of activity of stearoyl-CoA desaturase which is a key enzyme to convert saturated fatty acids to monoenoic fatty acids.

Phospholipid metabolism in V79-R membranes composed of phospholipid molecular species containing trans-monoenoic fatty acids.

The interrelationship between the inhibition of cell growth and changes in phospholipid molecular species was studied in the presence of elaidic, trans-11-eicosenoic, or brassidic acids in Chinese hamster V79-R cells. The addition of trans-monoenoic fatty acids to the medium inhibited cell growth and caused an increase in the total cellular content of phospholipids. However, there was no difference in the polar head group composition of these phospholipids among all the cells supplemented with trans-monoenoic fatty acids. Exogenous trans-monoenoic fatty acids were incorporated into cellular phospholipids to form novel phospholipid molecular species. Phospholipid synthesizing enzyme activities bound to the membranes composed of phospholipid molecular species of trans-monoenoic fatty acids were determined. Cholinephosphotransferase [EC 2.7.8.2] and ethanolaminephosphotransferase [EC 2.7.8.1] activities were decreased by trans-11-eicosenoic acid, but not changed by elaidic acid. Glycerophosphate acyltransferase [EC 2.3.1.15] activity was increased by elaidic acid and decreased by trans-11-eicosenoic acid. Cholinephosphate cytidylyltransferase [EC 2.7.7.15] activity was not changed by trans-monoenoic fatty acids.

Perturbation of phospholipid metabolism by erucic acid in male Sprague-Dawley rat heart.

Erucic acid was incorporated into cardiac phosphatidylserine and hepatic and cardiac sphingomyelin of male Sprague-Dawley rat. The fatty acid compositions of mitochondrial and microsomal phospholipids were similar in both liver and heart. The effect of a low fat diet and a diet containing erucic acid on the fatty acid composition of mitochondrial and microsomal phospholipids was also similar, except for the effect on sphingomyelin. However, the diet containing erucic acid influenced the metabolism of phosphatidylcholine of the heart but not of the liver, indicating that the turnover of 1-stearoyl-2-arachidonoyl phosphatidylcholine in the heart was inhibited by the diet containing erucic acid. On the other hand, the proportion of erucic acid in the free fatty acid was higher in the heart than in the liver.

Perturbation of lipid metabolism by palmitic acid in Chinese hamster V79-R cells.

1. The addition of palmitic acid or myristic acid to a medium containing delipidated fetal bovine serum resulted in severe inhibition of V79-R cell growth. The degree of inhibition by palmitic acid was concentration dependent. Simultaneous addition of oleic acid protected the cells from the inhibition by palmitic acid. 2. In the presence of palmitic acid, total phospholipid and triacylglycerol per cell increased to 2- and 13-fold, respectively. 3. Palmitic acid caused an increase in the proportion of palmitic acid with concomitant decrease of oleic acid in phosphatidylcholine, phosphatidylethanolamine and triacylglycerol. 4. Palmitic acid inhibited the synthesis of phospholipid molecular species with two monoenoic fatty acids. However, membrane flow of phospholipids from endoplasmic reticulum to plasma membranes was preserved. 5. About 70% of the triacylglycerol molecular species were those containing three saturated or two saturated and one monoenoic fatty acids. 6. Electron microscopy revealed a large amount of triacylglycerol and fiber-like membrane structures in the cells supplemented with palmitic acid.