Seven healthy volunteers and 3 hospitalized patients were given the same diet for 6 days. The mean intake of cholesterol was 359 mg/day. There was a large difference in the fecal amount of cholesterol and coprostanol amongthe subjects. The ratio of coprostanol/cholesterol ranged from 0.01 to 4.27. The subjects whose feces contained smaller amountof coprostanol excreted larger amounts of jS-sitosterol and crude fiber, suggesting that the various activities of intestinal flora were lower than the other subjects. The difference in the activity of intestinal flora to convert cholesterol into coprostanol was ascertained by incubating the feces anaerobically with egg yolk in vitro. It was also demonstrated that cholesterol was synthesized de novo and the amount corresponded to 0.1-0.6 g/day. The amounts of sterols in the feces of the other 17 hospitalized patients were also determined and there was an inverse relationship between the serum cholesterol and coprostanol/cholesterol ratio in the feces. These results suggested that the conversion of cholesterol into coprostanol by the intestinal flora might have an important role in the regulation of serum cholesterol level.

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We investigated variations in aluminum (Al) tolerance among rice plants, using ancestor cultivars from the family line of the Al-tolerant and widely cultivated Japonica cultivar, Sasanishiki. The cultivar Rikuu-20 was Al sensitive, whereas a closely related cultivar that is a descendant of Rikuu-20, Rikuu-132, was Al tolerant. These two cultivars were compared to determine mechanisms underlying variations in Al tolerance. The sensitive cultivar Rikuu-20 showed increased permeability of the plasma membrane (PM) and greater Al uptake within 1 h of Al treatment. This could not be explained by organic acid release. Lipid composition of the PM differed between these cultivars, and may account for the difference in Al tolerance. The tolerant cultivar Rikuu-132 had a lower ratio of phospholipids to Delta(5)-sterols than the sensitive cultivar Rikuu-20, suggesting that the PM of Rikuu-132 is less negatively charged and less permeabilized than that of Rikuu-20. We used inhibitors of Delta(5)-sterol synthesis to alter the ratio of phospholipids to Delta(5)-sterols in both cultivars. These inhibitors reduced Al tolerance in Rikuu-132 and its Al-tolerant ancestor cultivars Kamenoo and Kyoku. In addition, Rikuu-132 showed a similar level of Al sensitivity when the ratio of phospholipids to Delta(5)-sterols was increased to match that of Rikuu-20 after treatment with uniconazole-P, an inhibitor of obtusifoliol-14alpha-demethylase. These results indicate that PM lipid composition is a factor underlying variations in Al tolerance among rice cultivars.

SUMMARY This study was designed to examine whether defects of the meningeal anlage and intracranial hydrodynamic overload are involved in the pathogenesis of secondary cranioschisis after the neural tube closure. Chlorambucil (CA) 3.0–4.0 mg/kg administered to pregnant mice on day 7.5 of gestation (E7.5) caused abnormal blebs at the occipital region of embryos on E13.5 in a dose‐dependent fashion compared with control. At blebs, the mesencephalic ventricle was dilated, particularly on the dorsal midline and posterior to the pineal invagination. Histology showed fewer mesenchymal cells and vessels, as well as thinner neuroepithelial tissue than in controls. Transmission electron microscopy revealed that the cytoplasm of mesenchymal cells in the bleb region contained abnormal electron‐dense deposits, whereas deposits or other subcellular abnormalities were not evident in either the neuroepithelium or the surface ectoderm of the affected region. We administered 3.5 mg/kg of CA on E7.5 and studied the embryonic development. Mesodermal hypoplasia appeared on E11.5, whereas blebs were initially recognized on E13.5. On E15.5 and E18.5, the meninges and calvaria were hypoplastic, although no apparent cranioschisis was evident. To examine whether increased intracranial hydrodynamic pressure plus defects in the anlage of the meninges and cranium induces secondary cranioschisis, we injected kaolin into the cerebral ventricle on E13.5 to induce hydrocephaly. These embryos developed exo utero and we examined the morphology on E18.5. Hydrocephaly was induced and the defects were more severe in the meninges and cranium than in embryos exposed to CA alone, although cranioschisis was not histologically confirmed. These results suggested that hypoplasia in the mesoderm during early organogenesis underlies later abnormalities of the meninges and cranium, which may be involved in the pathogenesis of certain types of cranioschisis.