ABSTRACT. In addition to the lipoprotein-deficient d >1.25 fraction, haptoglobin was detected in the high-density lipoprotein (HDL) and the very high-density lipoprotein (VHDL) fractions from sera of calves with experimental pneumonia and cows with naturally occurring fatty liver. It was not found in the chylomicrons, very low-density lipoprotein and low-density lipoprotein fractions. Washing of the HDL fraction did not decrease the haptoglobin concentration. Transferrin and immunoglobulin G were immunoblotted to examine the possibility of contamination of the lipoprotein fractions by the d >1.25 fraction. The two serum proteins were detected only in the d>1.25 fraction, not in any lipoprotein fractions. The distribution pattern of haptoglobin in the lipoprotein fractions was distinct from that of serum albumin. Concentrations of haptoglobin in the HDL fractions from pneumonic sera were largely proportional to those in whole sera. Cholesteryl ester concentrations were decreased in sera from calves with pneumonia, as in cows with fatty liver. A protein immunologically related to hemoglobin was also detected in particular in the VHDL fractions from sera of both groups. These results suggest that haptoglobin or a complex with the hemoglobin-like protein may have a role or roles related to the lipid metabolism.-KEY WORDS: bovine, cholesteryl ester, haptoglobin, hemoglobin, high-density lipoprotein.J. Vet. Med. Sci. 61(2): 119-124, 1999 Holstein calves weighing 72 to 96 kg were used. A suspension of Pasteurella haemolytica (serotype 1, I29 strain; 1 × 10 9 colony forming units) was separately administered to right lungs of 10 calves using a fiber-optic bronchoscope [34]. Ten other calves received the vehicle (phosphate-buffered saline; PBS) alone and were used as controls. Serum was collected at 0 (1 hr before administration) and 0.25 (6 hr after), and at 1, 2, 3, 4 and 7 days after treatment. Calves were exsanguinated at day 1 (3 control and 3 inoculated calves), day 2 (3 control and 3 inoculated), day 4 (2 control and 2 inoculated) and day 7 (2 control and 2 inoculated), to examine pathologic changes and also to collect bronchoalveolar lavage fluids. Preparation of lipoprotein fractions: This was done as described previously [30], with slight modifications. Briefly, 4 ml of serum was overlaid with 2 ml of a solution of d=1.006 and centrifuged at 114,000 × g for 16 hr. The resulting top layer (1 ml) was collected as a mixture of chylomicrons and the very low-density lipoprotein fraction (CM-VLDL; d<1.006), and the next 1-ml layer was discarded. To the bottom layer (4 ml), 2 ml of a solution of d=1.182 was added, mixed and centrifuged at 114,000 × g for 20 hr. The top 1-ml layer was saved as the low-density lipoprotein fraction (LDL; d<1.163) and the next 1-ml layer was again removed. The resulting bottom layer (4 ml) was mixed with 2 ml of a solution of d=1.478 and centrifuged at 114,000 × g for 40 hr to collect the top 1-ml layer as the HDL (d<1.21). After removal of the next 1-ml layer, 0.88 ml of the d=1.478 s...

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Lecithin:cholesterol acyltransferase (LCAT) activity in serum was evaluated in spontaneous cases of fatty liver in cows. The enzyme activity of 631 +/- 62 U (mean +/- SEM, decrease in nmol of free cholesterol per h per ml of serum) in cows with fatty liver (n = 16) was significantly (p < 0.01) lower than that in cows without fatty liver (979 +/- 22 U; n = 16). In addition to the decrease in LCAT activity, the concentrations of phosphatidylcholine (a fatty aryl donor for esterification of free cholesterol) and of cholesteryl esters (products of the LCAT reaction) were reduced in the high-density lipoprotein fractions from cows with fatty livers. The concentrations in the serum of apolipoprotein A-I, an activator of LCAT, was also reduced in cows with fatty livers. These results suggest that the decreased LCAT activity, which may be attributable to impaired hepatic secretion or to the suppression of the activity in the plasma by reduced concentrations of phosphatidylcholine and apolipoprotein A-I, resulted in the lower concentrations of cholesteryl esters. Because cholesteryl esters are utilized in steroidogenic tissues for the synthesis of steroid hormones such as progesterone and glucocorticoids, and insufficient supply of the cholesterols may be of relevance to the reduced fertility and immune competence observed in cows with fatty livers.

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ABSTRACT. Lecithin:cholesterol acyltransferase (LCAT), the enzyme responsible for esterification of cholesterol in plasma, is reported to be implicated in the regulation of inflammation in laboratory animals. The purpose of the present study was to elucidate the possible relevance of LCAT in the pathogenesis of calf pneumonia induced by inoculations of Pasteurella haemolytica and bovine herpes virus-1 into the calf lung. Serum LCAT activity was significantly (P<0.01) reduced in calves inoculated with Pasteurella haemolytica. The concentration of cholesteryl esters (CE), the product of the LCAT reaction, was also decreased in the inoculated group. Decreases in LCAT activity and the CE concentration were similarly observed in calves in which bovine herpes virus-1 was inoculated. In both bacteria-and virus-inoculated calves, CE concentrations in the high-density lipoprotein fractions were distinctly decreased, whereas those in the low-density lipoprotein fractions were practically unaltered. The acute-phase proteins haptoglobin and serum amyloid A were detected in sera from the bacteria-and virus-inoculated calves; however, the two acute-phase proteins were also found in sera from the control calves. These results suggest that decreases in LCAT activity and the CE concentration are involved in the pathogenesis of pneumonia induced by inoculation of calves with Pasteurella haemolytica and bovine herpes virus-1, and also that the change in the LCAT system is more intimately related to the occurrence of calf pneumonia than the induction of acute-phase proteins such as haptoglobin.-KEY WORDS: bovine, cholesteryl ester, high-density lipoprotein, lecithin:cholesterol acyltransferase, pneumonia.J. Vet. Med. Sci. 61(10): [1101][1102][1103][1104][1105][1106] 1999 enzyme is also reported to be responsible for hydrolyzing platelet-activating factor, the phospholipid (PL) having a broad range of biologic effects, including neutrophil activation and smooth muscle contraction [10]. An association of hypocholesterolemia with calf penumonia is observed in field cases (Nakagawa, unpublished results).The decreased cholesterol concentration in calves with pneumonia implies that LCAT activity is also reduced in those calves, because CE (in cattle serum, more than 80% of cholesterol is CE) is the product of the LCAT reaction. The purpose of the present study was to examine whether LCAT activity and the LCAT-related lipid concentrations are affected in experimental calf pneumonia. Pneumonia was induced by inoculation of calf lungs with Pasteurella haemolytica and bovine herpes virus-1 (BHV-1), the two major pathogens for calf pneumonia [5,7,19]. We report here that LCAT activity and the CE concentration are reduced in calves with pneumonia induced by both pathogens. MATERIALS AND METHODS Bacterial and viral inoculations:Twenty 2-to 3-monthold male Holstein calves weighing 72 to 108 kg were used to induce experimental pneumonic pasteurellosis [9,20]. Calves were housed individually in pens, and were acclimated for 2 weeks. Room temper...