ABSTRACT. The present study was designed to determine the effects of physiological stress on milk-somatic cell counts (SCC) and function of bovine peripheral blood leukocytes (PBL). Nine healthy lactating cows were used in the examination. Five cows were transported 100 km for 4 hr (transported group; TG), and 4 cows were penned (non-transported group; NTG). Blood and milk samples were collected at 0, 2, and 4 hr after loading, and at 2 hr, and 1, 2, 3, and 6 days after unloading. The following activities were mea sured: adhesion receptor (CD 18 and L-selectin) expression of neutrophils and monocytes, migration capacity and percentage of apoptotic cells of neutrophils, serum soluble L-selectin (sL-selectin), plasma cortisol, and SCC. A significant increase in plasma cortisol and milk SCC was observed in TG. Leukocytosis, derived from neutrophils was recorded in TG, and was indicated by apoptotic measurement as an increase of young cells from the marginal pool. Increased migration and decreased surface expression of both L-selectin and CD 18 in neutrophils were observed after transportation. Elevated serum sL-selectin was also noted as a result of transportation. The present study indicated that transport stress modulates peripheral blood neutrophil function, particularly enhancing migration capacity, and c auses diapedesis across the mammary epithelium. Increased milk SCC in transported cattle might be due to these phenomena, and severe physiological stress may bring about an increase in SCC in milk.
In order to elucidate the mechanism of anemia in Japanese bovine theileriosis, we investigated the oxidative alteration of red blood cells (RBCs) in cattle infected with Theileria sergenti. As an index of RBC oxidation, the levels of 2¢,7¢-dichlorofluorescin-diacetate (DCFH) oxidation and malondialdehyde-thiobarbituric acid reactive substances (MDA-TBARS), and phosphatidylserine (PS) expression accompanying anemia were examined in experimentally infected cattle. Before the development of anemia, the concentrations of DCFH oxidation and MDA-TBARS were low, and PS expression on the surfaces of RBCs was hardly seen. However, during the onset of anemia, these levels began to increase remarkably in proportion to the decrease of packed cell volume and the increase of parasitemia in all infected cattle. During the serious stage of anemia, these oxidative indices reached their maximum values. Our findings indicate that oxidative damage and loss of membrane asymmetry in RBCs are related to the development of anemia in T. sergenti infection. This oxidative damage to the RBCs might play an important role in the pathogenesis of anemia in Japanese bovine theileriosis.
ABSTRACT. As a part of the elucidation of the pathogenesis of anemia in Theileria sergenti infection, oxidized-erythrocyte membrane proteins (OEMPs) collected from T. sergenti-infected calves were examined. The amount of OEMPs were seen to increase with the progress of the anemia and showed a maximum value around the crisis period of the infection. The increase of OEMPs coincided with band N os. 1, 2, 2.1, 3, 4.1, 5, 6, and 7. The majority of them was located at the Triton X-100 un-extractive phase, and was confirmed as cytoskeletal proteins. This evidence indicates the enhancement of erythrocytic oxidation, and suggests that it might be one of the aggravati ng factors of anemia in T. sergenti infection.
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