The activity of alkaline phosphatase (ALPase) was signifi-cantly enhanced in a human osteoblast cell line, HuO-3N1, when it was cultured in the presence of L-ascorbic acid 2-phosphate (ASA-P; a stable ascorbic acid derivative). With AsA-P in the culture, the level of ALPase activity increased approximately 3-fold without any effect on either the morphology or growth rate. This increase was dependent on the AsA-P concentration in the range of 0.2-2mM and required at least 48h incuba-tion with AsA-P. The ALPase mRNA level, however, remained ratherconstant irrespective of the enzyme activity. Removal of AsA-P from the precultured medium decreased the stimulatory effect of ascorbic acid on the ALPase activity, indicating that the effect was reversible. Dexametha-sone, an inducer for osteoblastic differentiation, enhanced the level of ALPase activity irreversibly, in parallel with the increase in the level of its mRNA. The enhancement of the ALPase activity by ascorbic acid in this cell line appeared to be independent of cell differentiation.
The effects of prenatal triethylene tetramine dihydrochlo-ride (Trien-2HCl) exposure on fetal mice have been investigated on gestational day 19. Trien-2HCl was given throughout pregnancy at levels of 0 (control), 3, 000, 6, 000, or 12, 000ppm as drinking water, ad libitum. At the level of 12, 000ppm, the frequency of total resorption tended to be high and that of fetal viability tended to be low, as compared to controls. Decreased maternal weight was observed in body, but not in liver, at the level of 12, 000ppm. Fetal body and cerebrum weights significantly decreased at the levels of 6, 000 and 12, 000 ppm; however, fetal liver weight remained unchanged. Maternal serum copper concentration was not affected by the Trien-2HCl. Fetal copper concentrations of liver and cerebrum were significantly lower in the Trien-2HCl-treated groups than in the controls, with levels decreasing in a dose-related manner. When the copper and zinc concentrations in the group treated at 12, 000ppm were compared with those in controls, significant decreases in both metals were observed in placenta but not in maternal liver. Changes in fetal zinc concentration varied by tissues: i, e., an increase in liver and no change in cerebrum. Fetal abnormalities were frequently observed in brain, and the frequency was increased with increasing levels of the Trien-2HCl. These results suggest that fetal brain abnormalities caused by Trien-2HC1 may be due in part to induction of copper deficiency, which is almost equivalent to that in brindled mutant mouse.
Calcium has been found to be indispensable in the preven-tion of osteoporosis. Recently, there has been a great deal of research into the best way to consume calcium. In this study, the effect of “powdered lobster shell” on bone metabolism was examined in ovariectomized osteo-porotic model rats. This powder has a good flavor and taste, and contains high quantities of calcium. Six-week-old SD-strain female rats were ovariectomized and were fed a low Ca diet (0.01% Ca and 0.3% P) for 32 days. Thereafter, the rats were divided into two groups; the control group was fed a control diet (0.3% Ca and 0.3% P) and an experimental group, the lobster group, was fed a lobster shell powder diet (0.3% Ca and 0.3% P) ad libitum for 30 days. The results were as follows: in comparison with the control group, the lobster group had significant increases in (1) bone mineral density [BMD (DEXA Hologic's QDR-1000] of lumbar spines and tibial proximal metaphyses, which are mainly trabecular bones, and BMD of tibial diaphyses, which is a mainly cortical bone, (2) the breaking force and energy of femur. These results suggests the lobster shell powder could be. a valuable source of dietary calcium in increasing BMD, breaking force and energy in osteoporotic model rats.
Phagocytosis of rat alveolar macrophages (AM) was enhanced by the infusion of arginine-rich solution for 7 days. The enhancement of phagocytosis by arginine-rich solution was due to not the difference in the distribution of AM subpopulations (I to IV) but the difference in phagocytic activity of AM in fraction IV. In the process of phagocy-tosis, there were no significant differences in the stages of migration, attachment, and digestion between control and arginine-rich solutions, although AM from fraction IV of rats infused with arginine-rich solution showed significantly higher ingestion of opsonized sheep red blood cells (SRBC) compared to that of control group. Furthermore, the production of macrophage-activating factor (MAF) from rat splenocytes was higher in arginine-rich group than that of control group. AM from fraction IV of rats fed a stock diet had a higher arginase activity and showed a significant increase of Phagocytosis following in vitro incubation with L-arginine (25 and 50mM) for 24 h. From these results, the enhanced phagocytosis of AM by arginine-rich solution may be due to the increased phagocytosis of AM from fraction IV, in which the higher sensitivity of AM from fraction IV to arginine and the higher production of MAF from splenocytes following the infusion of arginine-rich solution participate.
In order to study the effects of different proteins on α-linolenic acid (α-LnA) metabolism, rats were given the diet added respec-tively with milk casein and soy-protein isolate (SPI) as sources of proteins and perilla oil as a source of lipid. The results obtained are as follows. The ratio of (C20:3+C20:4)/C18:2 in liver microsomal PL, liver PE fraction, and kidney PE and PC fractions was significantly lowered by the SPI treatment when compared to the casein treatment, similarly to the already established results. In the liver microsomal PL and PE and PC fractions of liver and kidney in rats treated with SPI, there was also observed a significant decrease or a decrease tendency in the (C20:4+C20:5)/C18:3 ratio. A similar tendency was again shown in the ∑(n-3)M/C 18:3 ratio indicating metabolic conversion from C18:3(n-3) to C22:6. On the other hand, contrary to the ratios of (C20:3+C20:4)/C18 : 2, ∑(n-3)M/C18:3, and (C20:4+ C20:5)/C18:3, the (C22:5+C22:6)/C20:5 ratio which is the parameter for metabolic conversion of C20:5(n-3) was elevated in the PE and PC fraction of liver, heart and kidney in the SPI group compared to the casein group. Then, further analysis of the metabolic process from C20:5 to C22:6 showed that the C22:5/C20:5 ratio increased while the C22:6/C22:S ratio decreased in the SPI group compared to the casein group. Based on these results, it is assumed that the metabolic process from C 18:3 (n-3) to C20:5(n-3) and from C22:5 to C22:6 is affected by SPI but that the elongation process from C20:5(n-3) to C22:5(n-3), on the contrary, is rather accelerated by SPI.
Glucosone (D-arabino-hexos-2-ulose), a typical enediol prod-uct formed both in the Maillard reaction and γ-radiolysis of sugars, decreased survival of Chinese hamster lung V79 cells, which were in-cubated under MEM for 4 h. Inhibition of the decrease in cell servival by catalase and SOD suggests the role of active oxygen species, namely H2O2 and O22+, in the biological effects of glucosone. H2O2 was formed in the medium during oxidative degradation of glucosone. Inhibition of the formation of H2O2 by SOD indicates that the formation of H2O2 and the consequent decrease of the cell survival was enhanced by O2-. These results suggest that the mechanisms of the effects of glucosone on the mammalian cells in the absence of Cu2+ are different from those in the presence of Cu2+.
We surveyed the diet of a group of inhabitants in a moun-tainous area where goitre was endemic. The amount of iodine supplied by the diet was determined by analyzing foods with gas chromatography with electron-capture detection. The mean daily intake of iodine per person was between 286.4 and 1, 134.4μg. These values are within acceptable ranges recommended by several authors. The dietary supplies of proteins, fats and carbohydrates were also all within the ranges recommended by the FAO/WHO. Although goitre was endemic in the area studied, no dietary deficiency in iodine supply was found in any of the families investigated. Thus the ultimate cause of the endemic will have to be sought in other etiologic factors.
The effect of chitin at the level of 5% in the diet on cholesterol absorption and metabolism was studied in Wistar rats fed on diet containing beef tallow (7%) and cholesterol (1%). When compared with pair-fed controls, rats fed on diet containing chitin had: (1) similar weight gain and feed efficiency, (2) lower apparent protein digestibility, (3) equivalent liver steatosis, (4) reduced levels of liver triglycerides and cholesterol, (5) similar levels of serum and fecal cholesterol, (6) higher excretion of triglycerides in feces.
The effect of dietary safflower phospholipid (Saf PL) on the postprandial changes of steroids in the small intestinal and cecal contents was examined in rats fed a hypercholesterolemic diet. The triglyceride mixture (SP-Oil) containing a comparable amount of linoleic acid to Saf PL was used as a reference fat source. Saf-PL suppressed the elevation of plasma cholesterol levels at all times after meal intake, when compared to SP-Oil. The reduction of plasma cholesterol in rats fed the Saf PL diet was exclusively observed both in chylomicron plus very low density lipoprotein (VLDL) and low density lipoprotein (LDL) fractions. The rate of gastric emptying was not modified by the Saf PL diet. The level of neutral steroids in the small intestinal contents was almost comparable in both groups, but in the cecal contents and feces it was significantly higher in rats fed the Saf PL diet. On the other hand, the level of acidic steroids in the small intestinal contents tended to be higher in rats fed the Saf PL diet than in those fed the SP-Oil diet, whereas in the cecal contents and feces it was comparable in the two diets. These results suggest that Saf PL causes the accumulation of neutral steroids in the cecum due to the rapid transit through the samll intestine.