The contents of ascorbic acid (AsA) and erythorbic acid (ErA) in the tissues of guinea pigs intraperitoneally injected with AsA and/or ErA were determined to learn the difference in their retention in the tissues. After 10d of AsA depletion, the guinea pigs were intraperi-toneally injected with 5mg of AsA, or 5mg of ErA, or 5mg of each. At day 5 of repletion, the guinea pigs were killed and liver, adrenal glands, spleen, and kidneys were removed. AsA and ErA in these tissues were measured by using HPLC. The contents of AsA in the tissues of only the AsA-injected guinea pigs were similar to those of the AsA- + ErA-injected guinea pigs. The contents of ErA in the tissues of the ErA-injected guinea pigs were higher than those of the AsA- + ErA-injected guinea pigs, but apparently lower than the contents of AsA in the AsA-injected guinea pigs. ErA was scarcely retained in the tissues of guinea pigs.
This study was conducted to examine, in detail, the histological changes in the femurs of suspended ovariectomized (OVX) mice to assess the role of mechanical stress on bone remodeling. Suspended-OVX, suspended-sham-ope, nonsuspended-OVX, and non-suspended-sham-operated mice underwent operations 8 weeks after birth. Immediately after operation, hypokinesia/hypodynamia was created by a suspension harness for one week. Five specimens in each group were sacrificed 9 weeks after birth. The trabecular bone of the femurs in the suspended-OVX mice was removed and replaced extensively by bone marrow. The number of tartrate-resistant acid phosphatase (TRAP)-positive cells was larger in the suspended-OVX mice than in the remaining three groups. No significant differences in the number of TRAP positive cells were found between the suspended-sham-ope, nonsuspended-OVX and nonsuspended-sham-ope mice. The femurs of the OVX mouse with suspension “hypokinesia/hypodynamia” thus exhibits extensive trabecular bone loss in association with an increase of osteoclasts.
The present study was aimed to investigate the effects of indigestible dextrin and polydextrose, soluble dietary fibers with low molecular weight, on lipid metabolism and disaccharidase activities of intestinal mucosa in rats fed a high sucrose diet. Their effects were compared with those of well-known soluble fibers, pectin, and guar gum, and also with an insoluble fiber, cellulose. Dietary fibers added to diets at the 5% (w/w) level were a-cellulose, pectin, guar gum, indigestible dextrin, and polydextrose. Male Sprague-Dawley rats were given free access to test diets for 6 weeks. Body weight gain was the lowest in rats fed guar gum, the highest in rats fed cellulose, and in-between in rats fed other diets. Although guar gum, pectin, and indigestible feeding dextrin had lower plasma lipid values than cellulose feeding did, the differences were statistically insignificant. Liver triglyceride of the guar gum-fed group was about a third that of the cellulose-fed group, but although those of rats fed polydextrose, indigestible dextrin, and pectin were lower than that of cellulose, the differences were insignificant. Liver cholesterol and phospholipid concentrations were similar among groups. Daily fecal excretion of total lipid, cholesterol, and bile acids were highest in rats fed guar gum, followed by pectin-fed and cellulose-fed rats, and the lowest in rats fed indigestible dextrin and polydextrose. Jejunal sucrase activity was low in the order of guar-gum, polydextrose, indigestible dextrin, pectin, and cellulose. The results indicate that the hypolipidemic effect of soluble dietary fibers would be lessened with reduction in molecular weight, but that the lower sucrase activity by soluble fibers with low molecular weight might be beneficial for hypoglycemic effect.
We reported in the previous paper that rats fed a curdlan diet showed significant increases in the weight of the cecum and its contents, a decrease in fecal wet weight, a retardation in the transit time of the gastrointestinal tract, and morphological changes of the ileal and cecal mucosal surface when compared with the rats fed a cellulose diet. In the present study, we intended to learn if the curdlan effects on the mor-phological structure of intestinal mucosa were reversible. When rats were fed on the curdlan diet for 2 weeks followed by a cellulose diet for another 2 weeks, the cecum and cecal contents were not different from those of the cellulose group. The transit time of the gastrointestinal tract of the curdlan followed-by-cellulose group was shorter than that of the curdlan group, whereas it was longer than that of the cellulose group. In scanning electron micrographs, the ileal villi of the curdlan followed-by-cellulose group were normal, as in the cellulose group. However, their ileal and cecal microvilli were similar to those of the curdlan group, that is, the microvilli were crowded and more tightly packed, and some ap-peared to have been squeezed out. From these results, it was concluded that the effects of the curdlan feeding were only partially reversible, but the effects on the surface structure of intestinal mucosa were still sus-tained even after curdlan feeding of 2 weeks was discontinued. This might result from response to the high viscosity of the intestinal contents remaining after discontinuation of the curdlan.
To investigate the effects of orally administered reduced-glutathione (GSH) and oxidized-glutathione (GSSG) on liver GSH repletion and liver injury, acetaminophen (AAP) highly loaded rats were used. Orally administered GSH, dependent on dosage, indicated a protective effect against AAP-induced hepatotoxicity. This effect was associated with a recovery of liver GSH levels. Orally administered GSSG also indicated liver GSH recovery and hepatotoxicity inhibition to the same extent as orally administered GSH. Because intraperitoneally administered GSH did not indicate liver GSH recovery, the replenishment of GSH levels after orally administered GSH is thought to be produced through the degrada-tion of GSH into its constituent amino acids in the intestine and their re-synthesis in the liver. On the other hand, orally administered GSH indicat-ed a lower liver GSH recovery than orally administered cysteine prodrugs did, although the hepatotoxicity inhibitory degree was similar. Thus orally administered GSH may have another hepatoprotective system besides the resynthesis of its constituent amino acids. The current study estab-lishes that orally administered glutathione, both GSH and GSSG, is a useful tool to recover liver GSH levels and to prevent liver injury.
Rat liver cytosolic alcohol dehydrogenase (ADH) activity is known to be significantly higher in females than in males. To elucidate a possible mechanism of sex difference in the ADH activities, we studied the in vivo effects of the administrations of β-estradiol, progesterone or testosterone, and castrations (orchiectomy and ovariectomy) on the ADH activities in male and female Sprague-Dawley adult rats. Furthermore, we studied the ADH activities in six liver portions of sham-operated male, orchiectomized male, and female rats. The ADH activities were higher in orchiectomized male rats than in sham-operated male rats. These results were observed in all liver portions. The administration of testosterone (5 mg/kg BW, twice a day for 7d) to orchiectomized male rats significantly decreased ADH activities. The ADH activities in ovariectomized female rats were comparable with those in sham-operated female rats. The administration of β-estradiol (50μg/kg BW, once every 2d for 20d) or progesterone (75μg/kg BW, once every 2d for 20d) to rats increased the ADH activities in males more than in females. These results suggest that the inhibitory action of androgen and the slight facilitatory actions of progestin and estrogen are involved in the mechanism of sex difference in adult rat liver cytosolic ADH activity.
Lysosomes were isolated from the livers and from the kidneys of rats treated or not treated with the cysteine proteinase inhibitor leupeptin, and the levels of the intralysosomal serum albumin of the leupeptin-treated rats were compared with those of the saline-treated control rats. Leupeptin caused an intralysosomal accumulation of albumin in vivo because of its potent inhibition of lysosomal protein degradation. In fact, the lysosomes isolated from the livers and kidneys of leupeptin-treated rats almost completely lost their ability to degrade rat albumin in vitro. These findings show that the lysosomes are subcellular sites of the degradation of unlabeled serum albumin in these tissues. They also suggest that cysteine proteinases sensitive to leupeptin are involved in the lysosomal degradation of albumin. Albumin was degraded by total lysosomal enzymes in vitro. It was also degraded by the lysosomal extract being devoid of cathepsins H and J, prepared from rat kidney. The degradation of albumin by total lysosomal enzymes in vitro was greatly suppressed by a cysteine proteinase inhibitor, cystatin a, with no inhibition of cathepsins B and L. It was slightly suppressed by N-(L-3-trans-propylcarbamoyloxirane-2-carbonyl)-L-isoleucyl-L-proline (CA-074), a selective inhibitor of cathepsin B, and by pepstatin, an inhibitor of cathepsin D, whereas it was markedly suppressed by a combination of cystatin α and either CA-o74 or pepstatin. These and associated findings show that cystatin α-sensitive cysteine proteinase(s), which is distinct from cathepsins B, H, L, and J, and cathepsins B and D are involved in the lysosomal degradation of albumin.
A sandwich enzyme-linked immunosorbent assay for the soybean allergen, which consists of a monoclonal antibody (D4) as the fixing (first) antibody and another peroxidase-conjugated monoclonal antibody (C5) as the second, has been developed. Both D4 and C5 monoclonal antibodies strongly bound to the guanidine HCldenatured allergen, Gly m Bd 28K. Therefore the samples used in the present experiment were extracted with sodium phosphate buffer (pH 8.0) con-taining 6M guanidine and 10 mM 2-mercaptoethanol, then completely dialyzed against phosphate-buffered saline (PBS). The dialyzed samples were subjected to the assay. Various soybean products were observed to contain the allergen at high concentrations, such as soybean protein isolate (SPI), tofu, kori-dofu, and yuba, but its contents in soy milk and abura-age were found to be low. In fermente products such as natto, soy sauce, and miso, and even in the processed foods with soybean protein isolate (SPI), the allergen was not detected. These results were also confirmed by an immunoblotting technique with D4.
A thiamin-binding protein was isolated from sunflower seeds. Its molecular mass was estimated to be 230 kDa by gel filtration. The protein was suggested to be composed of six subunits, which con-sisted of polypeptides linked by disulfide bond(s). The protein contained a large amount of glutamine or glutamic acid (19.9 mol%) and aspa-ragine or aspartic acid (11.1 mol%). The levels of tryptophan and valine in the protein were low. These properties of the thiamin-binding protein were similar to those of helianthinin. Optimum pH for the thiamin-binding activity of the protein was 8.0 to 9.0. The thiamin-binding activity was not inhibited by thiamin monophosphate, thiamin pyrophosphate, oxy-thiamin, or pyrithiamin. These properties of the thiamin-binding protein from sunflower seeds were similar to those from buckwheat seeds, but not to those from rice seeds and sesame seeds.
In this study, male Sprague-Dawley rats weighing 70±5g were divided into a control (normal) group and three different diabetes mellitus (DM) groups that were supplemented with catechin-free (DM-OC), 0.5% catechin dietary (DM-0.5C), and 100 catechin (DM-1.OC). The animals were maintained on an experimental diet for four weeks. At this point, they were injected with streptozotocin (STZ) to induce diabetes, and they were sacrificed on the 6th day to determine the activities of phospholipase A2 (PLA2) and the changes of phospholipid species by catechin supplementation. In liver tissues, no significant differences were found between the PC hydrolysis of a normal group and a diabetic group; however, PE hydrolysis of the DM-0C, DM-0.5C, and DM-1.OC groups increased by 68.9%, 34.01%, and 26.9%, respectively, compared with the normal group. Although the PLAz activity of the DM-OC group in the liver tissues increased 91 % compared with the normal group, the PLA2 activity of DM-0.5C and DM-I.OC, which were fed catechin, increased 50% and 56%, respectively, compared with the normal group. In the liver tissues, peroxide values of the DM-OC, the DM-0.5C, and the DM-1.0C groups were increased 109%, 32.8%, and 46.7%. respectively, compared with the normal group. Based on these results for STZ-induced diabetic rats, lipid peroxidation seems to be accelerated specifically with the increased PLA2 activities.Thus if antioxidants like catechin were supplementation, the activity of PLA2 and PE hydrolysis can be altered and the accumulation of lipid peroxide would be decreased. Therefore we concluded that the antioxidant catechin for diabetic animals can significantly reduce PLA2 activities and lipid peroxide formation.
The main objective of this work was to perform a com-parative study of the antinutritional and/or toxic properties of phyto-hemagglutinin and trypsin-chymotrypsin inhibitor extracted from the seed of a commercial cultivar of edible bean used in Brazil. Bean pro-teins were extracted in acidic salt solution and fractionated by dialysis and centrifugation, then freeze-dried. The total freeze-dried bean extract and the globulin or albumin protein fraction were resuspended in distilled water and heated (100°C, 30 min) for inactivation of hemagglutinin. Diets were prepared with unheated bean protein fractions and heated ones (100% trypsin inhibitor activity, but 0 % phytohemagglutinin activity). As a result, the inhibition of growth and poor dietary protein utilization were observed in rats fed diets containing unheated bean protein fractions, but not in rats fed diets containing heated fractions. It was thus assumed that phytohemagglutinin is the main antinutritional and toxic factor in dry bean (Phaseolus) protein and that trypsin inhibitor (Bowman-Birk type) did not interfere with rat growth.
Background: Peroxidatively modified low-density lipopro-tein (LDL) may contribute to the atherosclerotic process; therefore, pro-tecting LDL against peroxidation may reduce or retard the progression of atherosclerosis. We evaluated the effect of α-tocopherol on copper-catalyzed LDL peroxidative modification. Methods: The protective effects of a-tocopherol on copper-catalyzed LDL peroxidative modification were examined by measurement of the concentration of lipid hydroperoxides in LDL and by the provision of LDL cholesterol to lymphocytes via the LDL receptor-mediated pathway. Results: The measurement of concentration of lipid hydroperoxides in LDL showed that a-tocopherol inhibited the peroxidative modification of LDL. Also, α-tocopherol preserved the ability of LDL to be recognized by LDL receptors in peripheral blood lymphocytes to the same extent as native LDL. Conclusion: These findings indicate that α-tocopherol may protect LDL against peroxidative modification, maintaining its ability to act as a ligand for LDL receptors in vivo.
Free radicals and lipid peroxide formation are related to tissue damage. This damage is thought to be associated with various diseases. To accurately assess the degree of lipid hydroperoxidation in biological materials, three different thiobarbituric acid (TBA) assay methods and the measurement of phosphatidylcholine hydroperoxide (PCOOH) by the chemiluminescence-HPLC (CL-HPLC) method were compared. Iron and copper deficiencies in rats reduced the contents of these metals. The addition of iron and copper to liver homogenates produced dose-dependent increases and decreases in TBARS, respectively. TBARS measured by the Shinnhuber method slightly increased with the addition of copper. The measurement of PCOOH was less affected by the addition of these metals. TBARS did not reflect lipid peroxidation when different concentrations of metals were present in the samples. The TBARS level is thus not a suitable marker for the assess of lipid peroxidation. PCOOH, accumulated as a primary peroxidation product from membrane phospholipids in the liver, was found to be a more appropriate marker for the estimating hepatic lipid peroxidation in the iron- and/or cop-per-deficient condition.
The effects of dietary sesamin (a mixture of sesamin and episesamin, 1: 1, w/w) on ketone body production and lipid secretion were studied in isolated perfused liver from rats given sesamin. Feeding sesamin at the dietary level of 0.2% from 14 to 16 d resulted in an enlargement of liver weight. Ketone body production was significantly elevated in the livers perfused with oleic acid in comparison with those perfused without an exogenous-free fatty acid, and sesamin feeding caused a stimulation of ketone body production, especially when exogenous oleic acid was provided. On the other hand, the ratio of fl-hydroxybutyrate to aceto-acetate, an index of mitochondrial redox potential, tended to increase in the livers perfused with oleic acid compared with those without fatty acid, though it was consistently lowered by dietary sesamin. The cumulative secretion of triacylglycerol, but not of cholesterol, by the livers from sesamin-fed rats was decreased markedly, especially when exogenous oleic acid was provided, suggesting an inverse relationship between the rates of ketogenesis and triacylglycerol secretion. These results suggest that dietary sesamin exerts its hypotriglyceridemic effect at least in part through an enhanced metabolism of exogenous-free fatty acid to oxidation at the expense of esterification in rat liver.
This study was performed to elucidate the effect of whey hydrolysate formula on the transfer of an antigen into serum and milk. The concentrations of β-lactoglobulin in serum and milk were positively correlated (p<0.01). The concentration of β-lactoglobulin in serum tended to become low in the mouse and to be accompanied with a high level of fecal anti-β-lactoglobulin IgA concentration. The fecal anti-β-lacto-globulin IgA of mice fed hydrolysate formula for 12 weeks was sig-nificantly higher than that of the control formula-fed mice (p<0.05). These results suggest that a high level of intestinal IgA elicited by the feeding of hydrolysate formula may reduce the transfer of β-lactoglobu-lin into serum and milk.