735 Lipoprotein-Cholesterol Levels in Young Rats Fed Diets Either Supplemented or Deficient in Selenium and/or Vitamin

Abstract

Cow milk may r e s u l t i n neonatal hypocalcemic t e t a n y i n term i n f a n t s a t one wk of aae. Current US cow milk formulas a r e modified t o have l o w e r "~ contents and should minimize adverse e f f e c t s on Ca metabolism. However t h e s e formulas s t i l l contain more P (33-40 mgldl ) vs breast milk (13 mgldl) and t h e r e a r e no s t u d i e s on iCa and P i n formula vs breast fed infants i n t h e f i r s t 6 mos of age. W e hypothesized t h a t t h e higher i n t a k e of P i n formula vs breast fed i n f a n t s r e s u l t s i n g r e a t e r serum P but lower iCa. In a Z4 f a c t o r i a l design cross-sectional study controlled f o r sex, race, season and d i e t , we evaluated serum Ca, iCa and P by d i e t (formula vs b r e a s t ) i n 119 normal, term i n f a n t s <6 mo of age. No differences i n serum Ca, iCa o r P by season, race o r sex were found. Total serum Ca did not d i f f e r between breast-and bottle-fed with means (tsem) of 9.75 (0.09) and 9.73 (0.06) mgldl. However, iCa (Radioiiieter e l e c t r o d e , N a d u l t s 4.8-5.2 mg/dl, CV 1.1-2.68) was lower i n b o t t l e -(5.27+ 0.02 mg/dl ) vs breast-fed i n f a n t s (5.38t0.03) (p=0.005). Serum P was h~g h e r (6.98+0.08) f o r b o t t l e -vs 6T44 (t0.10) i n breast-fed (ptO.OO1). Therewere no c o r r e l a t i o n s of C-terminal o r i n t a c t PTH by radioimmunoassay with iCa o r P. Thus, serum iCa i s lower and P i s higher i n formula-vs breast-fed i n f a n t s . W e speculate t h a t t h e lower Ca:P r a t i o i n cow milk formula (1.3:l) compared t o t h a t of breast milk ( 2 : l ) may be responsible f o r t h e s e observed differences. SD) were anesthetized, bile ducts were cannulated and the jejunum (J) catheterized. To compare the distribution of the NAMs, a group of rats (n=7) had 1 ml of a solution containing 1 t o 10 mM taurocholate (TC), 3H-TC, and both 1%-PEG and Poly R-478 instilled into the J. To measure TC absorption, a second group (n=8) received solutions containing TC, 3H-TC and Poly R-478. At the end of the study, J and ileum were divided into 8 segments, homogenized, and digested in 1M KOH. The absorbance of Poly R-478 a t 515 nm was found t o be linear from .0002% t o .02g%. The Poly R-478 concentration in each segment was measured by spectrophotometry a t 515 nm and was used t o calculate TC absorption.Pol R 478 recovery was 96.3 + 9.7%. The distributions of Poly R-478and YoCIPEG were significantly correlated (r=.91, p<.001). The TC absorption rate was linearly related t o the TC concentration (y=.54x+.20, r=.98, p<.001) and was identical t o data calculated using PEG-4000. Poly R-478 is an effective NAM whose advantages include solubility in water, stability, easy and precise concentration determinations and nonradioactivity, allowing the simultaneous use of multiple radio-labeled substrates. The extensive use of this dye family in the food industry attests t o its applicability t o human and animal absorption studies.Stone ISpon. by Festus 0. Adibonopo). Heharrv Hedical Colleoe. -, ...