Certain fish are very rich sources of vitamin D as compared to most of the higher vertebrates which have insignificant amounts of this vitamin. Not only the teleosts, which possess a calcified skeleton, but also the elasmobranchs, which lack calcified skeleton, contain extremely high concentrations of this vitamin, leading to the speculation that the function of vitamin D in fish may be different from its known classical functions in terrestrial animals. Interestingly, the two most common calcemic hormones associated with Ca and P homeostasis in higher vertebrates are either missing [parathyroid hormone (PTH)] or inactive [calcitonin (CT)] in fish. In fact, these hormones appear to have developed after transition of life from water (Ca-P rich environment) to land (environment poor in Ca and P). Thus, living in an aquatic environment with a continuous rich supply of Ca and P, do fish need vitamin D? If so, does it need to be converted to its polar forms? Additionally what are the functions of vitamin D and its metabolites in fish? Since fish stand between the invertebrates and higher vertebrates in evolution, they serve as a unique model for the study of the evolutionary and physiological significance of vitamin D. Investigations have demonstrated that the source of a high amount of vitamin D in them is primarily through their food-chain (plankton). In addition, it appears from the studies in fish that vitamin D perhaps had no physiological function in the calcium-rich aquatic environment, and its metabolism was essentially for catabolic purposes. During the course of evolution, when life started on calcium poor terrestrial environment, vitamin D became functional and its metabolism, an anabolic one, was concerned with calcium homeostasis.
The physiological function of vitamin D in fishes still remains uncertain. Earlier we observed no relationship between vitamin D3 content of several freshwater fishes and their calcemic/phosphatemic status and bone mineral content. In the present study the effects of vitamin D3 and its metabolites, 25-hydroxy vitamin D3 (25-OH-D3) and 1, 25-dihydroxy vitamin D3 [1, 25-(OH)2D3], administration on serum calcium-phosphorus levels, intestinal calcium absorption, whole-body calcium-phosphorus uptake, and gill calcium binding protein (CaBP) activity in the freshwater fish, Tilapia mossambica (Tilapia) was examined. It was observed that vitamin D3 and its metabolites could alter neither serum calcium-phosphorus levels nor intestinal calcium absorption and gill CaBP activity in fish at various doses. Further, the whole-body uptake of labelled calcium and phosphorus was also unaffected by vitamin D3/1, 25-(OH)2D3 at different levels and/or at various lengths of time. Thus these studies indicate that unlike in terrestrial vertebrates, vitamin D3 or its metabolites are not needed for calcium-phosphorus homeostasis in fish.
The present investigation was directed towards finding the relative biopotency of vitamin D3 and D2 in fish. The freshwater column feeder fish Labeo rohita (Rora) was used for the study. The feeding of Rora with graded levels of vitamin D2 (550, 1, 100 and 1, 650i.u./kg diet) and vitamin D3 (1, 100 and 1, 650 i.u./kg diet) resulted in no behavioural or morphological changes in comparison with the group fed a vitamin D-deficient diet. Also, the growth rate, feed efficiency, mortality rate, carcass protein, total lipids, calcium and phosphorus were found to remain unaltered in the vitamin D-deficient fish and fish fed any form of the vitamin. Further, there is no difference in any of the above parameters between the different doses of vitamin D3 or vitamin D2. Thus, the results of this study indicate that both of the forms of vitamin D (D2 or D3) are not biologically active for Rora (Labeo rohita) as a representative of freshwater fish.
About half the pregnant women in developing countries suffer from iron-deficiency anemia. The treatment of choice for these patients includes iron compounds such as ferrous sulfate. It was recently shown that a concomitant administration of vitamin A with ferrous sulfate increases iron-induced hematopoietic effect. In the current study, the efficacy of various routes of administration of vitamin A with ferrous sulfate in deferoxamin-treated anemic rats were compared. The work reveals no difference among various routes of administration, including several alternates of oral and intramuscular injection of vitamin A and ferrous sulfate for 28 d. It was therefore concluded that the therapeutic effect of vitamin A in iron-deficiency anemia is probably not via its influence on iron absorption from the gastrointestinal tract.
The effect of α-tocopherol enrichment of low- and high-density lipoproteins on Cu2+-catalyzed lipid peroxidation in the hydrophobic core and in the hydrophilic envelope of lipoproteins was investigated by using two pyrene derivatives, namely, cholesteryl pyrenyl hexanoate (P6Chol) and pyrene dodecanoyl sulfatide (P12CS). The progressive decrease in fluorescence of P6Chol was used to monitor lipid peroxidation in the core of LDL and HDL, whereas that of P12CS was used to follow lipid peroxidation in the envelope of both lipoproteins. α-Tocopherol enrichment of LDL and HDL was obtained by incubating blood plasma at 37°C with different concentrations of the vitamin (25-500μM) before lipoprotein separation. The incorporation of α-tocopherol in LDL and HDL presents a progressive, time-dependent increase up to 200μM α-tocopherol, then a plateau up to 500μM. In the envelopes, the added tocopherol causes a great decrease in the rate of peroxidation and a dramatic increase in the latency phase in both lipoproteins. In the cores the lengthening of latency phase resulting from α-tocopherol enrichment was by far greater in LDL than in HDL, and the decrease in the rate of peroxidation in both lipoproteins was less than in the envelopes.
An isolation of 9Z β-carotene from Dunaliella bardawil was accomplished by low-pressure column chromatography with Ca(OH)2 column. Furthermore, it was stereoselectively synthesized by Wittig re-action between the C10-phosphonium salt 2 and 9Z β-apo-8'-carotenal 1, which was prepared by Emmons-Horner reaction of 9Z β-ionylidene-acetaldehyde 3 with phosphonates 6 and 7 or 8a and 9.
The effects of diets containing fats and oils or fatty acids on the lipid metabolism were investigated in male rats of the Wistar strain fed hypercholesterolemic diets, especially focusing our attention on the correlation between dietary oleic acid (OLE) contents and the levels of plasma and liver total cholesterol (T-CHOL) or the fatty acid profiles in plasma and liver CHOL-ester. In the rats fed the free (FR)-type fatty acids, the concentrations of plasma and liver T-CHOL were high and the amounts of neutral steroids excreted into the feces were low when com-pared with those of rats given the triacylglycerol (TG)-type fatty acids, showing that TG-type fatty acids suppress the intestinal CHOL absorption more than the FR-type fatty acids do. The concentrations of plasma T-CHOL were highest in rats fed the oleic acid (OLE)-rich diets, followed in order by rats supplied with the palmitic acid (PAL)-rich diets, the hydrogenated coconut oil (HCO) diet, and the linoleic acid (LIN)-rich diets; the lowest was in rats given tristearin (TSTE) and linseed oil (LIS) diets. A positive correlation was obtained between the dietary OLE contents and the levels of plasma and liver T-CHOL or OLE in the plasma and liver CHOL-ester, and an inverse correlation between dietary OLE contents and the amounts of excreted neutral steroids. These results suggest that the dietary OLE contents regulate the levels of plasma and liver T-CHOL in CHOL-loaded rats.
Energy expenditure (TEE) determined by the doubly labeled water technique (DLW) in 10 adult subjects (5 males and 5 females) was used, to evaluate the energy expenditure estimated from 24h heart rate monitoring records (HR method) for 2 d randomly sampled during 2 weeks of DLW study. Individual data on HR and oxygen consumption, obtained during a step test (resting conditions, and up and down at 3 or 4 stepping rates) and postabsorptive conditions (resting metabolic rate: RMR), were used to calculate three types of calibration regression line, i.e., straight-linear regression (EE-HR: A for TEEhr-A), log-linear regression (InEE-HR: B for TEEhr-B), and two-linear regression (flex-HR method: C for TEEhr-C). When the 24 h HR records were applied, these calibration regressions provided three estimates of TEE (mean±SD kcal/24h): TEEhr-A (3, 059±1, 246 in all subjects), TEEhr-B (2, 472±843), and TEEhr-C (2, 759±1, 228). Mean TEE determined by the DLW method (TEEdlw) was 2, 544±378 kcal/24h. Although no mean values estimated by HR methods were significantly different statistically from the mean value of TEEdlw, the variances of the estimates (e.g., SD) by the HR method were much greater than that of TEEdlw (between twofold and threefold). TEEhr-B estimated by InEE-HR regression provided the smallest differences from that of TEEdlw (mean difference of -3.1% with a range of -35.1- + 36.6%). From these observations, the following conclusions were made: 1) The estimates of TEE by HR are useful as a group mean, but interpretation of the individual TEE estimates requires caution because of great deviations from the reference values. 2) Among the calibration methods tested, the log-linear calibration regression (lnEE on HR) gives the best estimates of TEE by the HR method and is re-commended for use in future studies.
We studied the effect of the extract of wine phenolics (EWP) on blood pressure, vasorelaxing activity and aortic biomechanical prop-erties in stroke-prone hypertensive rats (SHRSP). Thirty-six 4-week-old male SHRSP/Izm rats were divided into 6 equal groups fed one of the following 6 diets: A control diet (plain laboratory diet), the control diet substituted with 0.5 or 1.0% polyphenolic compounds derived from the extract of apple phenolics (EAP), the control diet substituted with 0.5 or 1.0% polyphenolic compounds derived from the extract of tea phenolics (ETP), or the control diet along with drinking water containing 1.0% polyphenolic compounds derived from EWP. Systolic blood pressure (SBP) and body weight (BW) were checked once a week. At the end of the 8th week of feeding, all of the rats were sacrificed and the heart weight and aortic biomechanical properties were measured. The relaxa-tion effect of the addition of EWP on endothelium-intact aortic rings precontracted with prostaglandin (PG) F2α was also measured. Only EWP, not EAP or ETP, significantly lowered the SBP values as compared with the control group at the 4th, 7th and 8th weeks of feeding (p<0.05). The heart weight and ventricular weight, expressed as the percentage of BW, were significantly lower in the EWP group than in the control group (p<0.05). The aortic maximum stress was significantly increased (p<0.05), and the aortic incremental elastic modulus was significantly reduced (meaning higher elasticity) (p<0.001) in the EWP group as compared with the control group. The aortic rings showed concentrationdependent relaxation induced by EWP, and the relaxation was signifi-cantly greater than that induced by a commercial red wine preparation. In conclusion, EWP attenuated the elevation of blood pressure in SHRSP possibly by increasing the vasorelaxation activity. The aortic fragility and elasticity were also improved in EWP-fed SHRSP.
To determine the nutritional role of nucleotides, the in vitro and in vivo effects of exogenous nucleotides on the development of intes-tine were investigated. First, the in vitro effects of nucleotides on the proliferation and maturation of enterocytes were studied by using a human colon tumor cell line (Caco-2) and a rat normal small intestinal crypt cell line (IEC-6). Second, the in vivo effects of nucleotides were also studied in early weaned rats fed nucleotide-unsupplemented or high-nucleotide-supplemented diet. Nucleotide composition resembled that of human milk (CMP:UMP:AMP:IMP:GMP=10:1:1:1:1, in weight). Nucleotide supplement did not enhance Caco-2 cells proliferation; however, it sig-nificantly enhanced maltase and sucrase activities. In contrast, nucleo-tides supplement enhanced IEC-6 cells proliferation and maltase activity. CMP, predominantly contained in the mixture, enhanced most effectively the proliferation and maturation of cells. In the in vivo experiment, nu-cleotides significantly enhanced sucrase activity in the intestinal mucosa of early weaned rats. The results presented here suggest that a nucleotide supplement may enhance enterocyte proliferation and/or maturation in vivo and in vitro. Therefore exogenous nucleotides may play an impor-tant role in the development of the intestine.
The bioavailability of selenium (Se) in high-Se yeast (SeY) was evaluated by measuring tissue Se accumulation and glutathione peroxidase (GSHPx) activity. For 4 weeks, 4-week-old male wistar rats were fed a Torula yeast-based Se-deficient diet (basal diet) or a diet supplemented with a graded level (0.04, 0.08, 0.16, and 0.32μg/g) of Se as either sodium selenite or SeY, which was obtained from two different sources. Se supplementation did not influence growth, hematological values, or serum biochemical tests. Se contents and GSHPx activities in the liver, serum, and erythrocytes increased gradually with increases of the supplemented Se. At lower Se levels (0.04 and 0.08μg/g), selenite produced higher Se deposition and higher GSHPx activities than SeY did, but at a higher Se level (0.32μg/g), SeY showed higher measures. Strong corre-lations were detected between the supplementary Se levels and the tissue Se contents or GSHPX activities when the regression was fitted to this equation: R-Rb=mlogX+k, where R represented tissue Se content or GSHPx activity in rats fed the diet supplemented with Se at X level, Rb corresponding mean value in rats fed the basal diet, m slope, and k constant. The bioavailability of Se in SeY, as assessed by slope ratio analysis using selenite as a reference Se, was 135% to 165% in the tissue Se content and 105% to 197% in the GSHPx activities. These results indicate that Se in SeY is more bioavailable than selenite Se, and therefore it is the preferred form for supplementation.
Colonic absorption and distribution of lycopene, which in-hibited rat colon carcinogenesis in our previous studies, were investigated in Sprague-Dawley rats. Three groups of six rats each with or without a single-barreled colostomy at the mid colon were given a single intragastric or intracolonic dose of 0.2 mL of corn oil containing 12 mg of lycopene. Twenty-four hours later, all rats were sacrificed and the blood and some tissues were collected. The contents of lycopene in the samples were assayed by HPLC. Lycopene was detected in an appreciable amount in the liver, but only in trace amount in the serum of all rats treated with an intracolonic dose of lycopene and in rats with an intragastric dose. After an intragastric lycopene treatment, lycopene was detected in the mucosa of the proximal colon and of the distal colon of the colostomized rats, whose distal colon had been excluded from the fecal stream. A large amount of lycopene was recovered in the feces. None was detected in any sample from the control rats treated with an intragastric or intracolonic dose of plain corn oil. The results suggest that lycopene is absorbed from the colon and also from the small intestine. It might be concluded that both ways of ab-sorption contribute to a comparative amount of lycopene accumulation in the colon mucosa after ingestion of this carotenoid.
This study was carried out to evaluate the effects of tea catechins on fecal contents and metabolites of elderly people who were on a diet of solid food. The subjects were 35 residents in a long-term care facility who were all on the same diet, consisting of rice gruel and minced food. Tea catechins (300 mg), which were divided into 3 doses a day, were a meal supplement every day for 6 weeks. Fecal specimens were collected by the nursing staff, and their moisture content, pH, ammonia, sulfide, and oxidation-reduction potential (ORP) were determined before, during, and after the administration of tea catechins. In a comparison of values before the administration, all these fecal parameters decreased signifi-cantly during the tea catechin administration. After termination of the administration, these data tended to return toward the levels before administration. The reduction of such fecal parameters as moisture, pH, ammonia, sulfide, and ORP by tea catechin administration indicated very favorable improvements of the subjects' bowel conditions.
The effect of dietary red bell pepper (Capsicum annuum L.) on learning performance was studied in the senescence-accelerated mouse (SAM). An experimental diet, which contained 20% (w/w) lyophilized powder of red bell pepper, was fed to SAMP8 mice. The mice that received the experimental diet showed much better acquisition in passive avoidance tasks as compared with a control group given a common diet. This indicated that the dietary ingestion of red bell pepper ameliorated the learning impairment in SAMP8.