Hiromichi Ohtsuka

Iron and Ferritin Levels in the Serum and Milk of Bovine Leukemia Virus-Infected Dairy Cows.

Iron metabolism was examined in 15 bovine leukemia virus (BLV)-infected dairy cows (2.6–7.8u2009years old). BLV infection was detected by measuring serum antibody titer against BLV virus antigen (gp51). The anti-BLV antibody titers of the BLV-infected cows were significantly higher in serum than in milk; a single serum-positive animal lacked detectable anti-BLV antibodies in its milk. Iron and ferritin concentrations also were significantly higher in serum than in milk. Although most of the BLV-infected dairy cows had past or present anamneses (such as inflammatory diseases, including intramammary infection), the milk ferritin concentrations of the infected cows were significantly lower than those of normal cows; serum ferritin concentrations did not differ significantly between these two groups. The anti-BLV antibody titers in milk samples showed significant correlation with serum iron concentrations. These results suggest that BLV infection affects iron homeostasis through iron metabolism in the dairy cow mammary gland.

Heme-binding of bovine lactoferrin: the potential presence of a heme-binding capacity in an ancestral transferrin gene

Lactoferrin (Lf) and transferrin (Tf) are iron-binding proteins that can bind various metal ions. This study demonstrates the heme-binding activity of bovine Lf and Tf using biotinylated hemin. When both proteins were coated on separate plate wells, each directly bound biotinylated hemin. On the other hand, when biotinylated hemin was immobilized on an avidin-coated plate, soluble native Lf bound to the immobilized biotinylated hemin whereas native Tf did not, suggesting that a conformational change triggered by coating on the plate allows the binding of denatured Tf with hemin. Incubation of Lf with hemin-agarose resulted in negligible binding of Lf with biotinylated hemin. Lf in bovine milk also bound to immobilized biotinylated hemin. These results demonstrate that bovine Lf has specific heme-binding activity, which is different from Tf, suggesting that either Tf lost heme-binding activity during its evolution or that Lf evolved heme-binding activity from its Tf ancestral gene. Additionally, Lf in bovine milk may bind heme directly, but may also bind heme indirectly by interaction with other milk iron- and/or heme-binding proteins.

Effect of acetate Ringer’s solution with or without 5% dextrose administered intravenously to diarrheic calves

The objectives of this study were to evaluate the effects of intravenous acetate Ringer’s solution, with or without dextrose, on diarrheic calves with either experimentally induced or spontaneous diarrhea. In the experimental model, diarrhea was induced in nine healthy calves by administering cold milk (below 4°C) twice a day for 2 days. The calves were randomly assigned to the isotonic saline (ISS), acetated Ringer’s (AR) or acetated Ringer’s with 5% dextrose (ARD) groups, with three calves assigned to each group. The calves received 80 ml/kg of their designated solution, at a flow rate of 20 ml/kg/hr. Infusion of ISS, AR and ARD were all found to be safe and effective in increasing plasma volume. Intravenous (IV) infusion of ISS resulted in the acidification secondary to dilution, while AR and ARD infusion inhibited acidification. In addition, prevention of catabolism was observed only with IV infusion of ARD. Sixteen calves with spontaneous diarrhea were enrolled in the clinical study. The calves were randomly assigned to the AR or ARD groups, with eight calves being assigned to each group. The calves received 100 ml/kg of their designated solution, at a flow rate of 25 ml/kg/hr. Intravenous infusion of AR and ARD was found to be effective in increasing plasma volume and inhibiting acidification. Only infusion of ARD prevented catabolism, but it also led to hyperglycemia. Our results suggest that a solution containing dextrose may be beneficial for wasting diarrheic calves.