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Biomedical subjects

R R Eitenmiller

Publications and source records attributed to R R Eitenmiller.

At least 19 recordsLinked to original sources
PubMed1995

The folic acid requirements of starting broiler chicks fed diets based on practical ingredients. 1. Interrelationships with dietary choline.

Five experiments were conducted to evaluate the effect of dietary supplemental folic acid in starting broiler chick diets. In the first two experiments, basal diets based on corn and soybean meal contained 10 micrograms/kg vitamin B12 but no supplemental methionine or choline. Chicks showed curvilinear responses to folic acid supplementation with maximum growth and feed efficiencies from 1.45 mg/kg diet. The liver folic acid response was also curvilinear but reached a plateau at 1.70 mg folic acid/kg diet. The basal diet for three additional experiments contained soybean meal that had been washed with methanol to remove most of the choline. The basal diet contained only 750 mg/kg choline. Chicks exhibited a larger growth response to folic acid at low choline levels as evidenced by a significant folic acid by choline interaction. Choline and folic acid both increased tibia length and width. Folic acid supplementation increased but then decreased valgus deformity. Choline chloride supplementation also decreased the incidences of valgus and varus deformities and decreased bone ash, but increased the incidence of tibial dyschondroplasia. It is concluded that chicks fed practical ingredient-based diets require 1.3 mg folic acid/kg diet with low levels of choline, but only 1.2 mg folic acid/kg when choline is offered near the NRC recommended level of 1,300 mg/kg of choline.

Animals↗
PubMed1995

The folic acid requirements of starting broiler chicks fed diets based on practical ingredients. 2. Interrelationships with dietary methionine.

Two experiments were conducted to determine the effects of dietary supplemental folic acid and methionine on the performance of starting broiler chicks for 18 d. Four levels of dietary folic acid (.24, .54, 1.14, and 2.34 mg/kg) and four levels of dietary methionine (.45, .53, .61, and .69%) were fed in a factorial design. There were three replicates of eight chicks each per each treatment. The basal diet was based on corn, isolated soybean protein, meat and bone meal, and fish meal. It contained adequate amounts of all nutrients except methionine and folic acid. Increased growth was observed in chicks fed the basal diet supplemented with either folic acid or methionine. Total dietary folic acid and methionine plus cysteine requirements for maximum growth were estimated to be 1.80 mg/kg and .85% in Experiment 1 and 1.47 mg/kg and .87% in Experiment 2, respectively. There were interactions between dietary folic acid and methionine on weight gain in both experiments. Chicks fed the diet containing 2.34 mg folic acid/kg tended to have depressed growth, as in previous experiments. There was a significant linear feed conversion response to folic acid in Experiment 1 and to methionine in Experiment 2. There were both linear and quadratic liver folic acid responses to dietary folic acid in both experiments. There was no indication that dietary methionine had any effect on liver folic acid content. No differences in bone ash, hemoglobin, hematocrit, or incidence of tibial dyschondroplasia were detected due to methionine or folic acid supplementation.

Animals↗
PubMed1983

Copper, iron, and zinc contents of human milk at early stages of lactation.

The Cu, Fe, and Zn contents of early milk from 102 American mothers were examined in relation to stage of lactation, intake of prenatal mineral supplements, maternal age, parity, and previous history of lactation. A total of 412 samples was collected at three stages of lactation: early transitional (4 to 7 days postpartum); transitional (10 to 14 days postpartum); and mature (30 to 45 days postpartum). For the transitional and mature stages, representative samples of late evening (PM) and early morning (AM) feedings were collected. Diurnal variation in concentration was observed only for Fe. Concentrations of all elements decreased significantly at successive stages of lactation with Zn showing the greatest decline. Cu, Fe, and Zn contents (means +/- SEM) were 104.1 +/- 5.4, 96.5 +/- 6.5, and 520 +/- 20 micrograms/100 g in early transitional milk; 93.9 +/- 3.6, 85.4 +/- 4.5, and 410 +/- 10 micrograms/100 g in transitional milk, and 84.7 +/- 3.8, 76.1 +/- 3.8, and 290 +/- 10 micrograms/100 g in mature milk, respectively. No significant relationship was found between levels of Cu and Zn in milk and whether mothers had taken dietary supplements containing these elements. In addition, no significant correlations were found between maternal age, parity, or previous history of lactation and the elemental content of milk. Based on these data, it was estimated that fully breast-fed infants would receive approximately 0.11, 0.10, and 0.50 mg/kg per day of Cu, Fe, and Zn, respectively, during the neonatal period.

Circadian Rhythm↗
PubMed1983

Calcium, phosphorus, and magnesium contents of human milk during early lactation.

Early milk samples from 102 American mothers were examined for Ca, P, and Mg contents in relation to stage of lactation, intake of prenatal mineral supplements, maternal age, parity, and previous history of lactation. A total of 415 samples were collected at three stages of lactation: early transitional (4-7 days postpartum); transitional (10-14 days postpartum); and mature (30-45 days postpartum). No diurnal variations in element concentrations were observed in representative samples of late evening (PM) and early morning (AM) feedings collected during the transitional and mature stages. The mean concentrations for the major elements were highest in early transitional milk and in some cases decreased significantly (p less than 0.05) as lactation progressed. Ca, P, and Mg contents (means +/- SEM) were 26.3 +/- 0.6, 14.6 +/- 0.4, 5.3 +/- 0.1 mg/100 g in early transitional milk and 26.2 +/- 0.5, 13.3 +/- 0.3, and 5.0 +/- 0.1 in mature milk, respectively. Increasing uniformity in the elemental content of milk was noted among the mothers as lactation became established. No significant relationship was found between intake of dietary supplements containing Ca and Mg and levels of these elements in milk. Also, no significant correlations were found between maternal age, parity, or previous history of lactation and the elemental content of milk. From these data, it was estimated that fully breast-fed infants would receive approximately 33, 18, and 6.5 mg/kg/day of Ca, P, and Mg, respectively, during the neonatal period.

Calcium↗
PubMed1980

Human milk ribonuclease.

Two components having ribonuclease (EC 3.1.27.5) activity were isolated from human milk. Each component of human milk ribonuclease (RNAase) moved at a slightly different rate when electrophoresed on polyacrylamide gel but at the same rate when ultracentrifuged. The major component had a molecular weight of approx. 14 000, an isoelectric point of pH 7.9, and exhibited a broad absorbance maximum between 277 and 281 nm. Human milk RNAase hydrolyzed yeast RNA, poly(cytidylic acid) and poly(uridylic acid) but not DNA, poly(adenylic acid) or poly(guanylic acid). Maximum activity occurred at pH 7.7 and 60 degrees C. Amino acid analysis of the major component revealed a large number of alanine, valine, glycine and aspartic acids but no tryptophan or free sulfhydryl groups. Lysine was the N-terminal amino acid. Tryptic hydrolysis yielded 18 peptides, some of which are similar to those from bovine pancreatic RNAase. Human milk RNAase activity was increased in the presence of NaCl, KCl and sodium citrate and decreased by CaCl(2), MgCl(2), FeSO(4), ZnSO(4) and CuSO(4).

Amino Acid Sequence↗
PubMed1979

Application of gel permeation chromatography and nonaqueous reverse phase chromatography to high pressure liquid chromatographic determination of retinyl palmitate and beta-carotene in oil and margarine.

A high pressure liquid chromatographic method was developed using high pressure gel permeation chromatography (HP-GPC) and high pressure reverse phase chromatography (RP-HPLC) for quantitation of retinyl palmitate and beta-carotene. HP-GPC was used for fractionation of vitamin A active compounds from oil preliminary to quantitation on nonaqueous RP-HPLC. HP-GPC fractionation was completed on oil and margarine dissolved in methylene chloride by 2 elution passes through 2 muStyragel (100 angstrom) columns connected in series with methylene chloride as the mobile phase. RP-HPLC separation of retinyl palmitate and beta-carotene was achieved on muBondapak C18 (10 micrometers), using methylene chloride-acetonitrile (30+70). Based on 10 repetitive analyses, recoveries of added beta-carotene and retinyl palmitate from vegetable oils were 98.6+/-2.9 and 95.2+/-2.6%, respectively. The coefficients of variation were 2.9% for beta-carotene and 2.7% for retinyl palmitate. The determination of vitamin A activity in 7 margarine brands with label claims of 10% U.S.RDA/serving revealed that all but one of the margarines contained at least 94% of the label claim. Vitamin A activity in the margarines ranged from 90.6 to 110.8% of the label declaration.

Carotenoids↗
PubMed1976

Relationship between composition and stability of bovine milk lysozyme.

The amino acid analysis, peptide mapping, and heat stability of bovine milk lysozyme are presented. The bovine milk lysozyme molecule contains approximately 154 amino acids and is strikingly different in amino acid content from human milk lysozyme and egg white lysozyme. Tryptic hydrolysis yielded 26 peptides, all of which are unique from tryptic peptides of human milk lysozyme and egg white lysozyme. In addition, bovine milk lysozyme was more heat stable than human milk lysozyme at pH 4.0 but more labile at pH 7.0 and 9.0. Possible explanations for the differences in heat stability are discussed.

Amino Acids↗
PubMed1975

Arylamidase activity of Salmonella species.

Arylamidase activity in cell extracts of sonically cell treated suspensions of 23 Salmonella strains, including 12 strains of S. typhimurium, was investigated. All cultures hydrolyzed five of nine different neutral and basic substrates. Activity against aspartyl-, cystyl- histidinyl-, and isoleucyl-beta-naphylamide was negligible. Alanyl-beta-naphthylamide was the preferred substrate for the Salmonella species; however, specific activities ranged widely. Of several gram-negative organisms surveyed, all except Proteus vulgaris hydrolyzed alanyl-beta-naphthylamide at the fastest rate. The most preferred substrate for the Proteus culture was glycyl-beta-naphthylamide. No relationship could be shown between virulence and arylamidase activity for the Salmonella strains.

Amides↗
PubMedDate not supplied

A liquid chromatographic method for analysis of all-rac-alpha-tocopheryl acetate and retinyl palmitate in medical food using matrix solid-phase dispersion in conjunction with a zero reference material as a method development tool.

A liquid chromatographic method is described for analysis of all-rac-alpha-tocopheryl acetate and retinyl palmitate in medical food. The vitamins are extracted from medical food without saponification by matrix solid-phase dispersion and chromatographed by normal-phase chromatography with fluorescence detection. Retinyl palmitate and all-rac-alpha-tocopheryl acetate are quantitated isocratically with a mobile phase of 0.125% (v/v) and 0.5% (v/v) isopropyl alcohol in hexane, respectively. Results compared favorably with label declarations on retail medical foods. Recoveries determined on an analyte-fortified zero reference material for a milk-based medical food averaged 98.3% (n = 25) for retinyl palmitate spikes and 95.7% (n = 25) for all-rac-alpha-tocopheryl acetate spikes. Five concentrations were examined for each analyte, and results were linear (r2 = 0.995 for retinyl palmitate and 0.9998 for all-rac-alpha-tocopheryl acetate) over the concentration range examined, with coefficients of variation in the range 0.81-4.22%. The method provides a rapid, specific, and easily controlled assay for analysis of retinyl palmitate and all-rac-alpha-tocopheryl acetate in fortified medical foods.

Chromatography, Liquid↗
PubMedDate not supplied

Application of a tri-enzyme extraction for total folate determination in foods.

A tri-enzyme digestion procedure using chicken pancreas conjugase, alpha-amylase, and Pronase was evaluated to determine its usefulness in the microbiological quantitation of total folate in foods. Folate values obtained by traditional conjugase digestion were compared to those obtained by the tri-enzyme method for 12 food products that represent diverse matrixes. The tri-enzyme treatment increased measurable folate from most foods when compared to levels found after conjugase digestion. Largest increases were noted for tuna fish (51%) and yogurt (33%) after tri-enzyme digestion. For the 12 foods, a mean increase of 19% in measurable folate was obtained with tri-enzyme treatment. The study shows that traditional conjugase treatment does not completely free folate from complex food matrixes before microbiological analysis. Further, as other investigations have suggested, current accepted methods for folate analysis may be underestimating folate levels in foods.

Animals↗
PubMedDate not supplied

Vitamin A and vitamin E content of infant formulas produced in the United States.

Vitamin A (vitamin A palmitate) and vitamin E (alpha-tocopheryl acetate) levels were determined in 77 samples of fortified infant formulas manufactured by 4 firms in the United States from 1981 to 1983 and were compared by formulation base (soy, milk) and manufacturing firm. For vitamin A and vitamin E, the mean values (IU/100 kcal) were 454 +/- 95 (range 248-614) and 2.0 +/- 0.7 (range 1.1-5.0), respectively. No significant differences (alpha = 0.05) were found in levels (IU/100 kcal) of vitamin A and vitamin E between milk- and soy-based formulas. When the mean vitamin A and vitamin E levels of formulas produced by the various firms were compared on an IU/100 kcal or percent of label declaration basis, significant differences (alpha = 0.05) were found among firms. Mean vitamin A levels for the various products compared to label declarations ranged from 126% of declared for the ready-to-use formulas to 139% of declared for the powders. Mean vitamin E levels ranged from 97% of declared for ready-to-use formulas to 118% of declared for concentrates. Except for one sample that contained 248 IU vitamin A/100 kcal, the formulas met the requirements of the 1980 Infant Formula Act.

Chromatography, Liquid↗
PubMedDate not supplied

Method modification for liquid chromatographic determination of thiamine, riboflavin, and pyridoxine in medical foods.

A reversed-phased ion pair liquid chromatographic method developed for the simultaneous determination of thiamine (B1), riboflavin (B2), and pyridoxine (B6) in perchloric acid extracts of infant formulas was modified to include medical foods. UV detection of B1 and B2 was replaced by fluorescence detection, which resulted in improved sensitivity and specificity. B1 was detected by fluorescence after conversion to thiochrome by a postcolumn reaction with sodium hydroxide and potassium ferricyanide. The method uses a mobile phase of water, acetonitrile, hexanesulfonic acid sodium salt, ammonium hydroxide, and phosphoric acid adjusted to pH 3.6. The column is a 300 x 3.9 mm Nova Pak C18. Limits of detection were 0.05 microgram/mL for B1 and B2 and 0.01 microgram/mL for B6 by fluorescence detection. The system reproducibility was evaluated by completing 10 repetitive determinations on a medical food that gave a coefficient of variation of 5.9, 6.0, and 10.7% for B1, B2, and B6, respectively. Mean recoveries (n = 10) were 111, 96.3, and 113% for B1, B2, and B6, respectively. The results compared favorably with those by AOAC Official Methods 942.23, 940.33, and 961.15 for B1, B2, and B6, respectively.

Chromatography, Liquid↗
PubMedDate not supplied

Liquid chromatographic analysis of niacin in fortified food products.

An ion exchange liquid chromatographic (LC) method using an anion exchange resin column was developed for the determination of niacin in fortified foods. Samples were extracted by autoclaving with H2SO4 (1 + 1). Florisil open column chromatography was used to remove interferences from the sample extracts. Niacin levels were quantitated by an LC system using a 250 x 4.1 mm Hamilton PRP-X100 column, a mobile phase of 2% glacial acetic acid in water, and UV detection at 254 nm. The limit of detection was 0.11 micrograms niacin/mL, and the standard curve was linear from 0.24 to 0.80 micrograms niacin/mL. The system reproducibility was evaluated by completing 10 repetitive analyses on an infant formula and a macaroni product, which gave an average CV of 2.7%. Mean recovery (+/- standard deviation) was 99.8 +/- 7.7 (n = 15). The results compared favorably with those by the AOAC microbiological method.

Chromatography, Ion Exchange↗
PubMedDate not supplied

Zero control reference materials for infant formula methods development.

A zero control reference material (ZRM) for milk and soy-based infant formula was manufactured and characterized. The ZRM was free of retinyl palmitate and all-rac-alpha-tocopheryl acetate. The composition was similar to commercially available infant formula. The ZRM provides a valuable tool to ascertain method performance.

Animals↗