Pepsinogen and protein concentrations were determined in blood samples, collected from the left gastroepiploic artery and vein, and in abomasal lymph from 15 steers naturally infected with Ostertagia ostertagi and 4 uninfected steers. In steers with type-1 ostertagiosis, the concentration gradient between the mucosal interstitium and the blood alone could account for higher than normal serum pepsinogen concentrations. High interstitial pepsinogen concentrations may have resulted from increased epithelial permeability or increased pepsinogen production and secretion. However, in steers with type-2 ostertagiosis, the concentration gradient could not entirely account for the high serum pepsinogen concentrations, suggesting that capillary permeability or surface area may have been altered. Lymphatic uptake contributed pepsinogen to the blood in all infected steers.

In vitro transferability of penicillin, streptomycin, tetracycline, and erythromycin resistance from coagulase-negative staphylococci to Staphylococcus aureus and among the former species of bovine mammary gland origin was examined by bacterial mating on filters and by mixed-culture matings in broth and in skim milk. One hundred twenty-six (42 each on filter, in broth, and in skim milk) matings were performed among 37 isolates of different Staphylococcus species. Transfer of resistance to penicillin, tetracycline, or erythromycin was not detected. Of 51 matings performed to determine streptomycin-resistance transfer, 9 (3 each on filters, in broth, and skim milk) were successful. Nine strains representing 3 species of coagulase-negative staphylococci were tested as prospective donors of streptomycin resistance. Of these, 2 strains could transfer streptomycin resistance. A double-resistant donor, S hominis, not only transferred its streptomycin resistance to an S chromogenes strain lacking resistance, but also to an S aureus strain already carrying penicillin and tetracycline resistance. The transfer of streptomycin resistance from the donor S hominis, harboring 2 plasmids, to a plasmidless S chromogenes recipient strain was associated with apparent acquisition of the smaller plasmid of the donor by the recipient. The single-resistant donor, S epidermidis 681A, transferred streptomycin resistance to a tetracycline-resistant S aureus recipient. This strain however, failed to transfer its streptomycin resistance to another S aureus, 2 S hyicus, and 1 S xylosus recipient. Frequency of transfer of streptomycin resistance ranged from 1.1 X 10(-5) to 1 X 10(-4). When transfer of resistance was successful, attempts were made to characterize the transfer process. Conjugation appeared to be the mode of streptomycin-resistance transfer. Transfer of resistance between staphylococci of bovine mammary gland origin appears to be fairly uncommon. However, in view of the limitations of the procedures used, additional in vitro and in vivo work is needed to further assess the role of coagulase-negative staphylococci in dissemination of antibiotic resistance.

Female Sprague-Dawley rats were treated IM with 0, 2.5, 25, and 50 micrograms of clenbuterol HCl/kg of body weight/d for 21 days. In all treated rats, significant increase in body weight gain (P < 0.05) and improvement in feed conversion ratio (P < 0.05) were recorded. Hydrometra was observed in the uterus of treated rats, and histologically, it was possible to see dilatation of luminal glands and ovarian alterations. Clenbuterol treatment induced significant (P < 0.05) increase in uterine estrogen receptor concentration of rats treated with the 2 higher doses. Treatment apparently failed to enhance the rate of oxidative and conjugative biotransformations, except for glucuronidation of p-nitrophenol (P < 0.05). On the basis of the data obtained, we could affirm that high doses of clenbuterol affect the female reproductive system of rats inducing, almost in part, estrogen-like modifications, but probably by a different mechanism of action correlated to intense adrenergic stimulation.

An epidemiologic study of Pasteurella haemolytica serovar 1 (Ph1) in market-stressed feeder calves from 7 farms in eastern Tennessee was conducted. The nasal mucus of each calf was cultured sequentially at the farm of origin (day 0), at an auction market (day 133), and at a feedyard in Texas (days 141, 148, 155, and 169). Of the 103 calves tested, 77 were culture-positive, including 1 on day 0, 1 on day 133, 20 on day 141, 57 on day 148, 50 on day 155, and 14 on day 169. From the 143 Ph1 isolates, 20 enzyme profiles were determined by use of a commercial enzyme system that detects 19 enzymatic reactions; 4 antimicrobial susceptibility profiles were obtained, using the disk-diffusion method, which evaluated susceptibility to 11 antibacterial drugs. All isolates were positive for acid phosphatase and alkaline phosphatase, but were negative for alpha-galactosidase, alpha-mannosidase, beta-glucosidase, beta-glucuronidase, cystine aminopeptidase, N-acetyl-beta-glucosaminidase, and trypsin. Other positive enzyme reactions included: leucine aminopeptidase, 140 Ph1 isolates; phosphohydrolase, 90 isolates; alpha-fucosidase, 63 isolates; esterase (C4), 59 isolates; valine aminopeptidase, 30 isolates; esterase lipase (C8), 24 isolates; beta-galactosidase, 2 isolates; and alpha-glucosidase, chymotrypsin and lipase (C14), 1 isolate each. Thirty-four Ph1 profiles were identified, using combined enzyme and antimicrobial susceptibility profiles. The data indicate that the strains isolated during the feedyard period may have been determined more by farm of origin (P < 0.001) than by habitation with calves from other farms while in the feedyard. The combined enzyme and antimicrobial susceptibility profile method is a rapid and simple epidemiologic technique for tracking Ph1 strains in market-stressed feeder calves.

Haptoglobin (HP), an acute-phase protein, is detected in serum of cows with hepatic lipidosis (fatty liver). To assess the relevance of Hp in fatty liver, induction of Hp was examined, using conditions similar to those involving development of fatty liver in cows. Induction of Hp was achieved by a combination of dexamethasone administration (0.1 mg/kg of body weight) and 2 days' starvation. Haptoglobin appearance in serum was not associated with the increase of alpha 1-acid glycoprotein (a marker for inflammation). This treatment increased serum nonesterified fatty acids concentration and decreased serum triglycerides concentration. Protein kinase C activity was decreased in the cytosolic fractions of liver and mononuclear cells. Reduction of protein kinase C-catalyzed endogenous protein phosphorylation also was observed, particularly in the cytosolic fractions of the tissue and cells. Detection of Hp in serum of cows with fatty liver appears to be explained by the fact that Hp is induced by dexamethasone administration and starvation, which are similar to the condition responsible for fatty liver development. The change of protein kinase C-catalyzed phosphorylation was suggested to be involved in the induction of Hp in cows.

Foremilk, residual milk, and blood samples were studied for 10 days during acute mastitis episodes induced by endotoxin infused via the teat canal. Quarter milk and blood samples were collected frequently for 3 days after the infusion and thereafter once or twice daily. Leukocyte concentration in milk and blood was determined by flow cytometry. Within 2 hours after infusion of the endotoxin, clinical mastitis was observed. Total leukocyte concentration and proportion of neutrophils increased significantly (P < 0.05) by postinfusion hour (PIH) 2 in foremilk and by PIH 4 in residual milk. From PIH 2, serum albumin content and N-acetyl-beta-D-glucosaminidase activity were significantly increased in both fractions. Neutrophils were the predominant leukocyte population in both fractions until PIH 59. From PIH 72, lymphocytes were the predominant cell population until PIH 175 in foremilk and until PIH 223 in residual milk. Serum albumin content and N-acetyl-beta-D-glucosaminidase activity in residual milk was significantly lower than in foremilk from PIH 4 to 24 and from PIH 24 to 59, respectively. Regarding total and differential leukocyte counts, values for the 2 fractions followed the same pattern throughout the course of inflammation, probably owing to frequent sample collection. Total and differential cell counts tended to differ between the fractions during some periods, although differences were not statistically significant. When samples were taken less frequently, the total leukocyte concentration in residual milk was higher than that in foremilk. Although sample collections were frequent, clustering of immature neutrophils was not observed in the cytofluorogram of blood leukocytes in this study. Residual milk seems to be the fraction that best reflects the condition in the quarter at the particular time when the milk sample is taken. Results also indicate that residual milk reflects the condition of the secretory tissue, as well as the lower regions of the gland.