The incidence of fracture due to osteoporosis is increasing, and the deficiency of calcium intake has become a social issue as a predisposing condition to fracture. Small fish, which can be eaten whole with bones included, are an important dietary source of calcium. For efficient utilization of fish bones as a food, they must be softened. Bones of the horse mackerel were softened when they were heated or immersed in acetic acid, but components that were released from the bones were different under these two conditions. In this study, structural changes in fish bones caused by heating in water at atmospheric pressure and under pressure were studied. The bone of the horse mackerel was heated for a predetermined period in water. The crystalline structure of the bone was examined with an X-ray diffractometer, and its inorganic components were measured by ICP-AES. Fish bone heated in water showed a clearly different crystallinity compared with untreated fish bone. The X-ray diffraction pattern of heated fish bone resembled that of hydroxyapatite. These results suggest that organic materials rather than calcium and phosphorus are released from fish bone during heating. Measurement of inorganic components of fish bone after heating showed that minerals such as calcium, phosphorus, and magnesium were mostly retained in the bone. The amount of crude protein decreased in the fish bone but increased in the cooking water with prolonged heating. The release of part of the protein into the cooking water may be a possible cause of the crystallinity improves in heated fish bone. Fish bone also showed changes in the structure and were softened after heating, while most of its calcium content was retained. The use of fish bone softened by cooking to facilitate mastication is expected to contribute to an increase in calcium intake.
The effects of peptide chain length on the absorption of soybean hydrolysates by the rat small intestine were investigated by the perfusion. Two types of soybean hydrolysates, a small peptide (SP; average peptide chain length: 3.2) and a large peptide (LP; average peptide chain length: 5.2), were prepared for this experiment. Krebs-Ringer phosphate buffer (pH 7.0) containing 0.5% (w/v) of either of the two types of soybean hydrolysates was perfused through a 15-cm length of rat jejunum for 70min. After the perfusion, samples were collected; and the total amount of amino acid was then measured by an amino acid analyzer (Hitachi L-8500) after hydrolysis. The absorption rate of each amino acid was subsequently determined. The absorption rate for glycine, alanine, isoleucine, leucine histidine, arginine, phenylalanine, and proline in SP was significantly greater than that for those in LP. The total amino acid absorption of SP was significantly greater than that of LP. There were no significant differences in the net absorption of water in the buffer solutions of SP and LP. We thus concluded that SP is more greatly absorbed than LP in the intestinal perfusion model of the rat small intestine.
The effect of L-carnitine on glycoprotein status was studied in serum, liver, kidney, heart, and brain of young and aged rats. The levels of protein, hexose, hexosamine, sialic acid, and fucose were low in aged rats. L-Carnitine was administered intraperitoneally (300mg/kg body weight/day) for 7, 14, and 21 days. Supplementation of aged rats with L-carnitine demonstrated a time-dependent normalization of glycoprotein status. There was no such significant variation upon carnitine administration to young rats. From our observations we conclude that carnitine is effective in normalizing the age-associated alterations in glycoproteins and can be used in aged rats in order to minimize the age-associated disorders in which free radicals are the major cause.
Maintenance of appropriate proportions of n-6 and n-3 fatty acids in brain phosphatides has been considered important for normal brain function. Experiments were undertaken in rats to ascertain the influence of dietary alterations in the ratio of linoleic to α-linolenic acid on the expression of membrane-bound enzymes. Fats with ratio of 18:2 n-6 to 18:3 n-3 equivalent to 120, 40, and 8 (achieved through suitable blending of safflower and soybean oils) were fed to three groups of weanling rats over a period of 16 weeks. Synaptosomal membranes were isolated by subjecting the brain homogenates to discontinuous sucrose gradient ultracentrifugation. These membranes were used for the assay of enzyme activities and fatty acid analysis. Higher dietary intake of α-linolenic acid enhanced the activities of acetyicholinesterase and Na+, K+-ATPase. These results suggest that dietary α-linolenic acid influenced the expression of enzymes, possibly through alterations in the fluidity of these membranes, as evidenced by the compositional changes in them.
The effects of zinc on acute pancreatitis were investigated in rats with cerulein-induced pancreatitis and taurocholate+trypsin-induced pancreatitis. The endogenous zinc concentrations in the serum and pancreas after the onset of acute pancreatitis was not different from those in normal rats. Orally administered zinc sulfate was well absorbed and was taken up by the pancreas in normal rats as well as in rats suffering from acute pancreatitis. Oral administration of zinc sulfate before induction of acute pancreatitis reduced the serum amylase activity and the wet weight of the pancreas in rats treated with cerulein or taurocholate+trypsin. Oral administration of zinc sulfate after the induction of acute pancreatitis also reduced the pancreatic wet weight in rats with cerulein-induced pancreatitis, and decreased the mortality rate in rats with taurocholate+trypsin-induced pancreatitis. N-(3-aminopropionyl)-L-histidinato zinc (polaprezinc), a chelate of zinc and L-carnosine, also decreased the serum amylase activity and pancreatic wet weight in both types of pancreatitis. These data suggest that zinc compounds may have a therapeutic effect on acute pancreatitis.
Serum concentrations of carotenoids, such as β-carotene, α-carotene, lycopene, cryptoxanthin, and lutein/zeaxanthin, and additionally the concentrations of retinol and α-tocopherol, were investigated by high-performance liquid chromatography (HPLC) of samples from 90 Japanese (56 males and 34 females) who took part in a mass examination held in 1997. At the same time, their serum lipid peroxides were measured by the hemoglobin-methylene blue (Hb-MB) method. Serum α-carotene, β-carotene, cryptoxanthin, and total carotenoids were significantly higher in females (151.6±23.8pmol/ml, 327.8±58.4pmol/ml, 375.4±97.8pmol/ml, and 1.9±0.3nmol/ml, respectively) than in males (84.1±11.5pmol/ml, 120.0±15.6pmol/ml, 135.0±18.2pmol/ml, and 1.3±0.1nmol/ml, respectively). These differences may be mainly due to increased intake of carotenoids in females. On the other hand, serum lipid peroxides in females were 81% of those in males. There was no correlation between fat-soluble vitamins and lipid peroxides in males and females. In the subjects high in serum total-cholesterol (≥220mg/dl), there was a negative correlation between lipid peroxides and lycopene in the females, suggesting that lipid peroxidation in the serum of females high in total-cholesterol may be inhibited by the fat-soluble antioxidant lycopene.