John A. Marchello

Lipoprotein receptors in copper-deficient rats: apolipoprotein E-free high density lipoprotein binding to liver membranes

Twenty-four male weanling Sprague-Dawley rats were randomly and equally divided into two dietary treatments, copper-deficient and adequate (0.7 mg and 8.0 mg Cu/kg diet, respectively). Deionized water and diet were provided ad libitum. After 8 weeks, rats were exsanguinated, membranes prepared from livers, and plasma high density lipoproteins (HDL) isolated by ultracentrifugation and agarose column chromatography. Heparin-sepharose affinity chromatography was used to isolate subfractions of HDL devoid of apolipoprotein E (apo E-free HDL). The apo E-free HDL derived from rats of each dietary treatment were iodinated and bound to liver membranes prepared from rats of both treatment groups. Total binding data, specific binding data, and computer derived estimates of maximum equilibrium binding (Bmax) indicate less binding was observed when lipoproteins and membranes from copper-deficient animals were used in the binding assay compared to controls. In addition, a 2 X 2 factorial analysis of binding parameters derived from all experiments demonstrated a significant lipoprotein effect, indicating the reduction in binding may be associated with apo E-free HDL obtained from copper-deficient rats. The present findings suggest a reduction in binding of apo E-free HDL to their binding sites may contribute to the hypercholesterolemia and hyperlipoproteinemia observed in copper deficiency.

Apolipoprotein E-rich HDL binding to liver plasma membranes in copper-deficient rats

Abstract Copper deficiency in rats raises plasma cholesterol concentration while reducing liver cholesterol concentration. One consequence of this cholesterol redistribution is the accumulation of a large high-density lipoprotein (HDL) particle rich in apolipoprotein E (apo E). The purpose of this study was to determine, using an in vitro binding assay, if the interaction of apo E-rich HDL with hepatic lipoprotein binding sites may be affected by copper deficiency. Male Sprague-Dawley rats were divided into two dietary treatments (copper-deficient and -adequate) and placed on a dietary regimen for 8 weeks. Subsequent to exsanguination, hepatic plasma membranes were prepared and apo E-rich HDL was isolated from rats of each treatment by ultracentrifugation, agarose column chromatography, and heparin-Sepharose affinity chromatography. Total binding and experimentally derived specific binding of 125I-apo E-rich HDl to hepatic plasma membranes indicated greater binding when lipoproteins and membranes from copper-deficient animals were used in the assay compared to controls. Scatchard analysis of specific binding data indicated that equilibrium binding affinity (Kd ) was also affected by copper deficiency. The hepatic binding sites recognizing apo E-rich HDL were not affected by EDTA or pronase, of relatively high capacity, and recognized a variety of other rat lipoproteins.

Effects of a direct-fed microbial on digestive-tract morphology of Holstein bull calves and performance and carcass characteristics of Holstein steers1

Two experiments were conducted to evaluate the effects of live cultures of Lactobacillus acidophilus and Propionibacterium freudenreichii on digestivetract morphology of neonatal–transition Holstein bull calves and performance and carcass characteristics of calf-fed Holstein steers. In Exp. 1, forty-three 1-d-old Holstein bull calves (42 kg of BW) were supplemented with a direct-fed microbial (DFM) consisting of L. acidophilus and P. freudenreichii. Treatments consisted of a control (n = 21) and a treatment (n = 22) of direct-fed microbial (5 × 108 cfu) supplemented daily in a commercial milk replacer. At the conclusion of the milk-feeding stage (weaning), 11 calves from each treatment group were slaughtered at the University of Arizona Meats Laboratory for gastrointestinal-tract collection. The remaining calves were abruptly weaned and moved to concrete-floor pens for 14 d before slaughter (DFM treatments were mixed in the diet). Samples of the rumen and ileum were collected at the time of slaughter and examined for gastrointestinal-tract morphology. Before weaning, average ileal height, crypt depth, and total height (villus + crypt) were greater in DFM treatment (P 0.10) were noted in daily intake or G:F between treatments during the finishing period. Overall, steers fed 1 × 105 L. acidophilus had no difference in final BW and ADG versus steers fed the control diet.

Microbial Growth and Successions on Steaks as Influenced by Packaging Procedures1

The influence of retail packaging procedures: (1) Bordens Resinite film overwrap; (2) Gas (1% CO, 40% O2, 59% N2) flushed for 2 min then overwrapped with the Resinite film; (3) packaged in a barrier bag and sealed with no evacuation of air on microbial growth and succession on steak surfaces was studied during 12 d of storage at 4°C. Growth on top and bottom surfaces for all packaged steaks did not differ significantly within most sampling periods. Similar growth patterns were observed on both steak surfaces, increasing (P <0.05) between d 3, 6, and 9 of storage. Pseudomonas dominated the microflora on steaks packaged in all treatments. However, Pseudomonas was the dominant organism on the steaks packaged in treatment 3 only through d 6; thereafter the microflora were dominated by Serratia . The numbers of Micrococcus , Brochothrix , and coryneforms were also increased with storage time in all treatments.

Animal Fat Composition and Modification

This chapter discusses the classification of lipids, with detailed information concerning fatty acids, their structures, and nomenclature, found in meat animals. A short discussion is presented regarding the analytical procedures that are presently utilized for fatty acid analysis of various meat animal tissues. Advanced technology has helped the analytical analysis immensely. Detailed information is presented regarding differences in fatty acid composition by species (ruminants versus nonruminants), breeds, sex, diets, and environmental factors. Furthermore, a comparison of milk and butter fatty acid composition is discussed; however, 90% of the milk consumed is produced by cattle with the remaining predominantly produced by other ruminants species (goats, sheep, buffalo). Detailed information is provided regarding procedures that may be incorporated to change the fatty acid composition of meat animal lipid depots, ranging from 10% to 40%. Some discussion is provided with regard to the health benefits that may occur from changing the composition of lipids in meat animals.