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  • Author or Editor: Toru Miyamoto x
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Abstract

Objective

To determine: whether apolipoprotein A-I (apoA-I) is secreted by calf liver parenchymal cells; the isoprotein pattern and association with lipids of secreted apoA-I; and effects of steroid hormones on apoA-I secretion.

Sample Population

6 male Holstein calves (1 to 2 weeks old) as a cell culture source.

Procedure

apoA-I in culture medium was detected by immunoblot analysis, and its concentration was measured by use of an ELISA. The isoprotein pattern was analyzed by use of two-dimensional polyacrylamide gel electrophoresis. Associations of apoA-I with cholesterol and phospholipids were examined by ultracentrifugal analysis of the culture medium.

Results

Concentration of apoA-I in culture medium increased linearly up to 24 hours. The protein synthesis inhibitors, actinomycin D and cycloheximide, suppressed apoA-I accumulation in the medium in dose-dependent manner. Molecular mass of this protein in culture medium was 28 kd, and was indistinguishable from apoA-I of plasma. Four isoproteins with different isoelectric points (1 = 5.75; 2 = 5.67; 3 = 5.58; and 4 = 5.46) were detected. Of these, isoprotein 2 was the major species. By comparison, isoprotein 4 was the predominant species in plasma, and isoprotein 5 (isoelectric point = 5.38) was newly detected instead of isoprotein 1. Approximately 33% of apoA-I in culture medium was found in lipid-rich fractions, whereas the rest was found in nonlipoprotein fractions. Dexamethasone (10−8 to 10−6M) significantly (P < 0.001) increased apoA-I concentration in the medium, and the stimulatory effect was significantly (P < 0.001) suppressed by the simultaneous addition of 10−5M progesterone. Progesterone itself (10−6 to 10−5M) had little effect on apoA-I secretion; estradiol (10−14 to 10−6M) also had no significant effect.

Conclusions

apoA-I is synthesized by calf liver parenchymal cells, and the secreted protein is modified during circulation. Moreover, apoA-I synthesis and secretion by the cells appear not to be largely influenced by hormones, except for dexamethasone. (Am J Vet Res 1997;58:811–815)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine whether annexins or haptoglobin could be detected in bronchoalveolar lavage (BAL) fluid specimens obtained from calves experimentally inoculated with Pasteurella haemolytica.

Animals

Twelve 2- to 3-month-old male Holstein calves.

Procedure

Pasteurella haemolytica was inoculated into the right lung lobes of each of 6 calves. Six other calves received vehicle alone and were used as control calves. Specimens of BAL fluid were obtained from 3 control and 3 inoculated calves 1 day after inoculation and from the other calves 2 days after inoculation. The amount of annexins I, II, IV, and VI, and haptoglobin in BAL fluid specimens was examined by use of immunoblot analysis.

Results

Annexins I and IV were detected in BAL fluid specimens obtained from the right lung lobes of each of the inoculated calves, but annexins II and VI were not. Annexin I also was found in BAL fluid specimens obtained from the left lung lobes of each inoculated calf and from left and right lung lobes of the control calves. By comparison, detection of annexin IV was essentially limited to the right lung lobes of inoculated calves. Haptoglobin was detected in some, but not all, BAL fluid specimens from the right lung lobes of inoculated calves, and its detection in BAL fluid was associated with serum proteins such as albumin.

Conclusions and Clinical Relevance

Annexin IV was detected most specifically in response to inoculation of P haemolytica. This protein could be used as a marker for inflammatory pulmonary disease caused by P haemolytica. (Am J Vet Res 1999;60:1390–1395)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine the cardiorespiratory effects of epidural administration of morphine alone and in combination with fentanyl in dogs anesthetized with sevoflurane.

Design—Prospective study.

Animals—6 dogs.

Procedure—Dogs were anesthetized with sevoflurane and allowed to breathe spontaneously. After a stable plane of anesthesia was achieved, morphine (0.1 mg/kg [0.045 mg/lb]) or a combination of morphine and fentanyl (10 µg/kg [4.5 µg/lb) was administered through an epidural catheter, the tip of which was positioned at the level of L6 or L7. Cardiorespiratory variables were measured for 90 minutes.

Results—Epidural administration of morphine alone did not cause any significant changes in cardiorespiratory measurements. However, epidural administration of morphine and fentanyl induced significant decreases in diastolic and mean arterial blood pressures and total peripheral resistance. Stroke volume was unchanged, PaCO2 was significantly increased, and arterial pH and base excess were significantly decreased. Heart rate was significantly lower after epidural administration of morphine and fentanyl than after administration of morphine alone. None of the dogs had any evidence of urine retention, vomiting, or pruritus after recovery from anesthesia.

Conclusions and Clinical Relevance—Results suggest that epidural administration of morphine at a dose of 0.1 mg/kg in combination with fentanyl at a dose of 10 µg/kg can cause cardiorespiratory depression in dogs anesthetized with sevoflurane. (J Am Vet Med Assoc 2004;224:67–70)

Full access
in Journal of the American Veterinary Medical Association

Summary

Parenchymal cells were isolated from the liver of male calves, and monolayer cultures formed were treated with glucocorticoids to examine whether haptoglobin, appearance of which is associated with hepatic lipidosis (fatty liver) in cattle, is induced by steroid hormones. Without addition of dexamethasone, only trace amounts of haptoglobin were detected in culture medium. With addition of dexamethasone (10−12 to 10−4 M), considerable amounts of haptoglobin were released into the medium. Maximal release was observed at concentrations of 10−8 to 10−6 M dexamethasone. Haptoglobin release was similarly induced by Cortisol, although the effect was less potent than that of dexamethasone. Actinomycin D (a known protein synthesis inhibitor) dose-dependently reduced amounts of haptoglobin released in response to 10−8 M dexamethasone. Dexamethazone also induced annexin I, which is known to be synthesized in response to glucocorticoids. Dexamethasone treatment resulted in reduced protein kinase C activity in the cell cytosol, which has been shown to be an early event in dexamethasone-treated cells. Other than glucocorticoids, estradiol induced haptoglobin release, whereas progesterone was less effective. The association of haptoglobin with hepatic lipidosis can be reasonably explained by the fact that haptoglobin production by the liver is induced by glucocorticoids and estradiol, and these steroid hormones are triggers for development of hepatic lipidosis in cattle.

Free access
in American Journal of Veterinary Research

Summary

Changes in serum alpha1-acid glycoprotein (α1 AG) concentration in cattle with hepatic abscesses were observed, and function of α1 ag was evaluated, particularly its influence on cellular immune response. Test cattle (n = 4) were inoculated with Fusobacterium necrophorum, control cattle (n = 2) were inoculated with inactivated bacteria, and naturally affected cattle (n = 11) were found in a slaughterhouse.

Determination of α1 ag was made by use of a single radial immunodiffusion method. The action on lymphocyte blastogenesis was determined by [3H]thymidine incorporation. Cultured lymphocytes from healthy cattle were treated with variable concentrations of α1 ag purified from serum obtained from cattle with hepatic abscesses and suppression of blastogenesis stimulated by each of 3 mitogens was measured.

In cattle with experimentally induced abscesses, serum α1 ag concentration increased for 7 to 10 days after F necrophorum inoculation, its change being parallel to that of sialic acid. High concentration of α1 ag was found in naturally affected cattle and was highly correlated to sialic acid concentration. Suppression of lymphocyte blastogenesis in cattle with experimentally induced hepatic abscesses was highly correlated to serum α1 ag concentration.

Free access
in American Journal of Veterinary Research