Comments on measurement of iron bioavailability in rats.
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Animals↗
Biomedical subjects
J W Erdman
Publications and source records attributed to J W Erdman.
Effects of purified dietary fiber sources on beta-carotene utilization by the chick.
Effects of various purified dietary fiber components on beta-carotene utilization by the chick were investigated in two experiments (expt.). Eight-day-old Columbian X New Hampshire male (expt. 1) or female (expt. 2) chicks were fed a vitamin A-deficient diet for 1 wk and then fed beta-carotene-supplemented diets containing 0% fiber, 7% arenaceous flour or 7% of a purified fiber source for 4 wk. Results of expt. 1 showed that hemicellulose, lignin and citrus pectin, but not arenaceous flour or polygalacturonic acid, depressed beta-carotene utilization by the chick, as measured by percentage of consumed beta-carotene stored in liver as vitamin A relative to the 0% fiber control. In expt. 2, effects of the methoxyl content of pectin were studied. High and medium methoxyl apple pectin, citrus pectin and polygalacturonic acid reduced storage of vitamin A in liver. Low methoxyl apple pectin had no significant effect on beta-carotene utilization. Thus, several purified forms of dietary fiber significantly reduced beta-carotene utilization by chicks when fed at the 7% supplementary level. Moreover, with pectin, there was an inverse relationship between methoxyl content of pectin and beta-carotene utilization.
Animals↗
Bioavailability of zinc to rats as affected by protein source and previous dietary intake.
The bioavailability of zinc from defatted soy flour, dried chicken meat or mixed (50:50 dry weight basis) soy flour and chicken meat included in egg white-based diets was investigated in rats. Following a 6-d experimental diet (9 ppm Zn) feeding period, marginally zinc-depleted weanling rats were fed a test meal, identical in composition to the experimental diet except that the protein source was labeled either intrinsically or extrinsically with 65Zn. Retention of 65Zn from the chicken test meal was significantly higher than that from the soy test meal. Retention of 65Zn from the mixed soy/chicken test meal was midway between the retention values for either protein alone regardless of which protein source was labeled. Intrinsic and extrinsic labeling techniques resulted in similar assessment of zinc bioavailability. Additionally, the influence of previous dietary protein source on zinc retention from a soy test meal was investigated. Retention of 65Zn from an intrinsically labeled soy test meal was higher in rats adapted to chicken protein than in rats adapted to soy protein. The levels of tibia zinc and tibia 65Zn were associated with whole-body retention of 65Zn.
Animals↗
Alterations in vitamin A and thyroid hormone status in anorexia nervosa and associated disorders.
Vitamin A and thyroid hormone status was investigated in 27 patients with anorexia nervosa. Subjects were divided into three groups based on eating behavior and serum carotene concentrations: anorexic (dietary restriction), normal carotene; anorexic, elevated serum carotene; bulimic, elevated serum carotene. All bulimic subjects fulfilling selection criteria were hypercarotenemic (weight loss and reduced metabolic rate). Data were compared to normal healthy volunteers. Serum retinol and retinol-binding protein levels were normal in all subjects whereas retinyl esters were elevated in the hypercarotenemic groups. Hypercarotenemia was primarily a result of elevation of vitamin A active carotenoids, especially beta-carotene. Diet was excluded from the etiology of hypercarotenemia. Thyroid hormones T4 and T3 were significantly depressed in hypercarotenemic groups and rT3 increased. A concomitant alteration in vitamin-hormone status is observed with progressive metabolic alterations: low T3, T4, and elevated retinyl esters in subjects with the hypercarotenemia associated with anorexia nervosa.
Adolescent↗
The effect of diet on retention by the rat of iron from a radiolabeled casein test meal.
Previous work has shown that weanling rats fed a soy protein isolate (SPI)-based diet retained less iron from a casein test meal than did rats fed a casein-based diet. In the present work this diet effect was further investigated. In experiment 1 rats were fed either SPI-or casein-based diet (about 25 ppm Fe) for 13 d, fasted overnight, given a 59Fe-labeled casein-based test meal, and refed either the same or the other diet for 7 d. 59Fe retention was determined by the percent of ingested label retained after 7 d. SPI reduced 59Fe retention when fed prior to the test meal (52.5 vs. 61.5%, P less than 0.001) and also when fed following the test meal (50.8 vs. 63.2%, P less than 0.001). In experiment 2a, exposure of SPI to steam at 108 degrees C for 30 min did not lessen the observed diet effect. In experiment 2b rats were fed either an SPI-or casein-based diet, and casein test meals were fed as above on days 14, 35 and 56. The SPI-based diet reduced 59Fe retention from the casein test meal fed on d 14 (58.2 vs. 68.0%, P less than 0.005), for the meal on d 35 there was no difference, and for the final test meal rats fed SPI retained more 59Fe (53.0 vs. 40.2%, P less than 0.01). In experiment 3 lactalbumin was shown to decrease 59Fe retention to the same extent as SPI (54.9 and 53.4%) as compared to casein (73.3%), whereas neither rapeseed protein concentrate (68.8%) nor oxalic acid (72.2%) had any significant adverse effect.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Ultrasonic attenuation and velocity properties in rat liver as a function of fat concentration: a study at 100 MHz using a scanning laser acoustic microscope.
This study examines the extent to which ultrasonic attenuation coefficients and velocity properties change between normal and fatty rat liver. The view of this problem is toward the application in clinical medicine in the future. Fatty livers were produced in rats by feeding them alcohol diets in liquid form. The animals were sacrificed and the fat concentration of the liver specimens determined. The fat concentration varied from 2.5% to 16.8% wet weight. The ultrasonic attenuation coefficient and velocity properties in 28 specimens were measured at 100 MHz with the scanning laser acoustic microscope (SLAM). Regression analysis was applied to the liver's ultrasonic propagation properties as a function of fat concentration. The results show that the attenuation coefficient increases at a rate of 1.08 dB/mm/% fat and the velocity decreases at a rate of 2.3 m/s/% fat as the fat concentration increases.
Animals↗
The effect of soy protein isolate in the diet on retention by the rat of iron from radiolabeled test meals.
The influence of soy protein isolate (SPI) in the diet on whole-body retention of extrinsically radiolabeled iron from test meals containing or not containing SPI was evaluated in marginally iron-deficient weanling rats. In experiment 1 SPI was compared with casein in a 2 X 2 factorial design: diets and test meals were either SPI-based or casein-based. Diets were fed for 13 days prior to the test meal and for 7 days subsequent to the test meal. Rats fed the SPI-based diet retained less iron from test meals than did rats fed the casein-based diet (66.1 vs. 74.8%, P less than 0.01). Experiment 2 showed that an SPI-based diet fed during the final 4 days of a 14-day pre-test meal period and subsequent to the test meal led to less iron retention compared to a casein-based diet. In addition to the observed diet effect, experiment 1 showed that iron retention was less from an SPI-based test meal than from a casein-based test meal, confirming previous reports of adverse effects of SPI on iron retention. The present experiments show that SPI can adversely affect from retention in two ways: by its presence in the diet before and after a test meal, and by its presence in a test meal.
Animals↗
Bioavailability of zinc to rats from defatted soy flour, acid-precipitated soy concentrate and neutralized soy concentrate as determined by intrinsic and extrinsic labeling techniques.
The bioavailability of 65Zn from intrinsically and extrinsically labeled soy flour, acid-precipitated soy concentrate and neutralized soy concentrate was evaluated in rats. Weanling rats were fed marginally zinc-deficient diets, providing 8 ppm zinc from one of these three soy products, for 7 days. The rats then received a radioactively labeled test meal, identical in composition to the previous diet except that the soy product was either intrinsically or extrinsically labeled with 65Zn. After the test meal the rats were again fed diets the same as those consumed prior to the test meal. Whole-body retention of 65Zn at 24 hours and 12 days as well as 65Zn retained in tibias of rats given meals containing neutralized concentrate-based meals was significantly lower than for rats given meals containing the soy flour or acid-precipitated concentrate. In addition, retention of 65Zn from the extrinsically labeled acid-precipitated concentrate-based meal was significantly higher than from the same product intrinsically labeled. These findings confirm the results of previous feeding studies from which it was suggested that neutralization of soy protein concentrates reduces zinc bioavailability to the rat. In addition, the results are taken to suggest that experimental conditions may influence the validity of the extrinsic labeling technique for zinc.
Animals↗
Effects of dietary phytate, calcium and magnesium levels on zinc bioavailability to rats.
Young rats were fed diets containing 12 mg Zn/kg and varied levels of sodium phytate for 21-day ad libitum feeding periods. In experiment 1, Ca levels were 0.3, 0.5, 0.8 and 1.0%, and phytate:Zn molar ratio varied between 0 and 50. In experiment 2, Ca was maintained at 0.3%, Mg levels were 0.07, 0.22 and 0.37%, and phytate:Zn molar ratios were 0, 10, 20 and 30 at each Mg level. Major response criteria were body weight gain and tibia Zn accumulation. Weight gain was not influenced by Ca level in the absence of phytate or by phytate at 0.3% Ca; it was increasingly depressed as phytate was increased and by each increase in Ca in the presence of phytate. Total tibia Zn content was decreased at the highest Ca level in the absence of phytate; increasing the phytate progressively depressed tibia Zn at all Ca levels. Mg and phytate additions did not affect weight gain. Tibia Zn tended to be depressed by Mg and by phytate but these effects were significant only at the highest levels of the combined additions. These data corroborate and extend previously published findings on Ca and phytate effects on Zn utilization and show bone Zn accumulation to be a more sensitive criterion than weight gain in this connection. They also indicate that Mg exerts a less pronounced effect on Zn utilization in phytate-containing diets than does Ca.
Administration, Oral↗
Toxic effects of fermented and unfermented sorghum meal diets naturally contaminated with mycotoxins.
Male weanling rats fed diets containing fermented and unfermented tannin-free sorghum meals naturally contaminated with traces of ochratoxin A, zearalenone, and an unidentified toxic substance developed anorexia. Mean changes in body weight over a 28-day feeding period for rats fed fermented and unfermented sorghum meal and ANCR casein diets of 8% protein were -2.8, +13.8, and +100.5 g, respectively. Rats fed fermented sorghum meal developed alopecia; hematological findings showed a decreased mean corpuscular volume, hypochromic microcytosis, balanced leukopenia, and hypoproteinuria . Histological findings showed testicular hypoplasia of the germinal epithelium and no mature spermatozoa. Necrosis and mineralization in Henle's loop were also observed. No damage was apparent to the liver, cerebellum, cerebrum, spleen, or adrenal glands.
Animal Feed↗
Determination of lycopene, alpha- and beta-carotene and retinyl esters in human serum by reversed-phase high performance liquid chromatography.
A rapid specific, microdetermination of the major human blood carotenoids by high performance liquid chromatography (HPLC) separation and quantitation at 466 nm is detailed in this paper. Serum retinyl esters can also be quantified utilizing the same separation procedure but detected at 325 nm. One hundred microliters of deproteinated serum were extracted with chloroform and injected on a reverse-phase column. Separation occurred within 16 min for all compounds of interest employing a mobile solvent of MeOH/AcN/CHCl3 (47:47:6). All compounds were quantified at the wavelengths cited by integrated peak areas using retinyl acetate as a daily standard. Analysis of serum from a hypercarotenemic anorexia nervosa patient and a person suffering from hypervitaminosis A are presented as examples of the clinical application of this procedure.
Carotenoids↗
Bioavailability of zinc in coagulated soy protein (tofu) to rats and effect of dietary calcium at a constant phytate:zinc ratio.
An assay was conducted with young albino rats to compare the bioavailability of zinc contained in calcium- and in magnesium-precipitated tofu to zinc supplied as the carbonate in egg white diets. Relative availability of zinc from both tofu preparations was 51% as measured by weight gain and 36-39% for log micrograms tibia zinc accumulation. In a separate experiment with zinc supplied at 9 mg/kg in all diets, the effect of increasing dietary calcium on weight gain and tibia zinc accumulation was tested. Performance of tofu-fed rats relative to zinc carbonate-fed rats at 0.4, 0.7 and 1.2% calcium was, respectively: 92, 67 and 48% for weight gain, and 70, 58 and 61 for tibia zinc content.
Animals↗
Effect of chronic alcohol consumption and moderate fat diet on vitamin A status in rats fed either vitamin a or beta-carotene.
The effect of chronic alcohol consumption on vitamin A metabolism was investigated in male rats. Liquid diets containing five times the NRC requirement for vitamin A and varied levels of ethanol were fed. The vitamin A content of the liver was decreased in rats receiving alcohol. Liver lipids were only slightly elevated in alcohol-fed rats. Hepatic vitamin A storage was also decreased in rats fed 30% calories as alcohol and beta-carotene or vitamin A at the NRC requirement level, but not in rats fed one-sixth the NRC requirement as vitamin A. The activities of alcohol dehydrogenase, NADPH cytochrome c reductase, and retinol dehydrogenase were not altered in hepatic or testicular tissue by the vitamin A or alcohol content of the diet. When an intragastric dose of [3H]retinyl acetate or [14C]beta-carotene was administered, fecal excretion of radioactivity was lower than controls in rats receiving 30% ethanol in the diet for a total of 4 weeks, for 1 week following 7 weeks of control diet consumption, and after an acute dose of ethanol. Recovery of the 3H label was greater in the testes of rats chronically consuming ethanol. When a solution containing [3H]retinyl acetate or [3H]beta-carotene with or without ethanol was injected into intestinal segments, no alterations in absorption of retinyl acetate or beta-carotene due to ethanol occurred. It is concluded that alcohol consumption results in decreased hepatic vitamin A storage, which is not due to the malabsorption of either retinyl acetate or beta-carotene, or to altered activities of several enzymes involved in ethanol and vitamin A metabolism.
Alcoholism↗
Bioavailability of trace mineral elements.
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Animals↗
Protracted hypervitaminosis A following long-term, low-level intake.
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Acne Vulgaris↗
Changes in lipid metabolism during retinoid administration.
Administration of oral vitamin A and the synthetic retinoids to humans and experimental animals has been accompanied by changes in lipid metabolism. these changes include alterations in serum, liver, and skin surface lipids. While the immediate cause(s) of the serum and liver changes remain(s) obscure, the skin surface lipid alterations appear to be secondary to changes in sebum production. The most marked effect of retinoid feeding seen in clinical or animal studies is that of hypertriglyceridemia. The increased serum triglycerides are found primarily in the very low-density lipoprotein (VLDL) fraction of the blood and occur during both the fasted and fed state. In rats, oral all-trans-retinoic acid, 13-cis-retinoic acid, and natural vitamin A have resulted in hypertriglyceridemia, while in man, 13-cis-retinoic acid, etretinate, and natural vitamin A have been reported to elicit this response. Current studies using the rat indicate that elevated serum triglycerides may be secondary to both increased liver secretion and decreased extrahepatic breakdown. Ongoing work from our laboratory and the possible primary causes of the systemic lipid changes are discussed.
Animals↗
Effect of dietary retinyl acetate, beta-carotene and retinoic acid on wound healing in rats.
The effects of feeding various levels and combinations of retinyl acetate, beta-carotene, or retinoic acid on skin wound healing in rats was investigated. Weanling male Sprague-Dawley rats were fed a vitamin A-free diet for 2 weeks to produce marginal vitamin A status. After a paravertebral incision was made and closed with suture, one of several diets were fed for either 5 or 14 days. Surgery and recovery did not reduce liver vitamin A nor serum retinol levels compared to nonoperated pair-fed controls. Supplemental retinyl acetate feeding at five times the NRC-suggested allowance resulted in a mild, but significantly increased postmortem wound tensile strength after 5 days compared to rats fed the suggested allowance. Although a low level of retinoic acid in the diet (1.3 microgram/g diet) depressed wound strength at 5 days, a higher level (5.2 microgram/g) increased the strength 57% above controls. Still higher levels (49.1 microgram/g) did not further increase the tensile strength of the wound. beta-Carotene fed the requirement level for 5 days (with compensation made for utilization as one-sixth that of retinol) doubled wound strength compared to rats fed the requirements as retinyl acetate. Vitamin A feeding did not enhance wound strength after 14 days of feeding. It is concluded that supplemental retinyl acetate, beta-carotene, or in some cases all-trans-retinoic acid can be effective in enhancing wound strength, 5 days, but not 14 days after surgery, of young male rats with marginal vitamin A status.
Administration, Oral↗
Retinoic acid and hypertriglyceridemia.
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Animals↗