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.

We used size-exclusion high-performance liquid chromatography (HPLC) to investigate the properties of the 2 isoforms of vitamin A-containing (holo) retinol-binding protein (RBP) in animals: the form that is bound to transthyretin (holo-TTR-RBP), and the form that does not bind to TTR (holo-free RBP). We also used radial immunodiffusion to measure immunologically active RBP (apo+ holo RBP). We compared the isoforms of RBP in animals with those of human beings to determine which animal is the best model of human RBP. Size-exclusion HPLC detected holo-free and holo-TTR-RBP in every animal species studied. Apparent concentration of holo-TTR-RBP varied among species: that of rabbits and dogs much greater than that of apes, sheep, goats, monkeys, rhinoceroses, felids, rats, human beings, and deer greater than that of pigs, zebra, and bison greater than that of penguins. Dogs have unusual RBP chromatograms; they have high concentration of RBP, but also appear to transport much of their vitamin A on proteins other than RBP, Human RBP antibody preparations could detect apo + holo RBP immunologic activity only in apes, monkeys, and felids. Apes and monkeys appeared to have complete cross-reactivity to human RBP antibodies. Felids may have substantial, but partial, cross-reactivity. Apes and monkeys appear to be the most relevant animal models for study of human RBP transport. However, there is a need for less-expensive models. Further research is needed, but in the interim, rats or sheep may be satisfactory for some purposes.

Nine adult female sheep were each surgically fitted with an Ivan and Johnston reentrant cannula in the cranial part of the duodenum just distal to the pylorus. By diversion (loss) of abomasal outflow, this model has been shown to consistently induce hypochloremic, hypokalemic metabolic alkalosis, accompanied by hyponatremia and dehydration. Each sheep was subjected to 3 treatment trials, each preceded by a 24-hour prediversion period, and a diversion period during which a syndrome of hypochloremia (68 +/- 2 mEq/L), hypokalemia, hyponatremia, and metabolic alkalosis was induced. Development of this syndrome was attributable to losses of large amounts of acid and electrolytes in the abomasal effluent. Mean total electrolyte contents of the effluent were: Cl-, 650 +/- 27 mEq; Na+, 388 +/- 23 mEq; and K+, 123 +/- 12 mEq, with total volume loss ranging from 3.6 to 10.0 L of gastric contents and pH ranging from 3 to 5. Decreases in plasma electrolyte concentrations also can be attributed to decreased intake, because anorexia developed shortly after the onset of diversion. Electrolyte losses in urine during diversion were minimal for Cl-(mean +/- SEM, 12.0 +/- 5.1 mEq), but were greater for Na+ (124.2 +/- 14.5 mEq) and K+ (185.1 +/- 31.2 mEq). Treatments consisted of 0.9% NaCl (300 mosm/ L), 3.6% NaCl (1,200 mosm/L, and 7.2% NaCl (2,400 mosm/L) administered over a 2-hour period, with the administered volume determined by the estimated total extracellular fluid Cl- deficit. Significant difference was not found among treatments, with all solutions resulting in return of clinicopathologic and physical variables to prediversion values within 12 hours of treatment. We concluded that rapid iv replacement of Cl-, with small volumes of hypertonic saline solution, is safe and effective for correction of experimentally induced hypochloremic, hypokalemic, metabolic alkalosis in sheep.

Development of 1- to 2-cell in vivo fertilized equine embryos cultured with or without uterine tubal epithelial cells (UTEC) was studied. One- to 2-cell embryos (n = 26) were collected surgically from the uterine tubes of pony mares 1 day after ovulation. Four- to 8-cell embryos (n = 9) were collected 2 days after ovulation. Presumptive zygotes and 2-cell embryos were cultured with (n = 17) or without (n = 9) UTEC, and all 4- to 8-cell embryos were cocultured with UTEC as positive controls. Uterine tubal epithelial cells were used as cell suspensions within 2 weeks after initiation of cultures. Embryos were cultured to blastocysts or until the embryo had morphologic degeneration. Six presumptive zygotes failed to cleave in vitro. Development to blastocysts of 1-cell (4 of 11) and 2-cell (2 of 6) embryos cocultured with UTEC was similar. Coculture of 1- to 2-cell embryos with UTEC significantly (P = 0.05) improved development to blastocysts, compared with culture in medium alone (35 vs 0%, respectively); however, development to blastocysts of 1- to 2-cell embryos cocultured with UTEC was less (P < 0.025) than that of 4- to 8-cell embryos cocultured with UTEC (35 vs 89%, respectively).

Cardiorespiratory effects of abdominal insufflation were evaluated in 8 dogs during isoflurane anesthesia. Each dog was studied 3 times, in 1 of the following orders of insufflation pressures: 10-20-30, 20-30-10, 30-20-10, 10-30-20, 20-10-30, and 30-10-20 mm of Hg. Anesthesia was induced by use of a mask, dogs were intubated, and anesthesia was maintained by isoflurane in 100% oxygen. After instrumentation, baseline values were recorded (time 0), and the abdomen was insufflated with nitrous oxide. Data were recorded at 5, 10, 15, 20, 25, and 30 minutes after insufflation. The abdomen was then desufflated, with recording of data continuing at 35 and 40 minutes. Mean arterial pressure increased at 5 minutes during 20 mm of Hg insufflation pressure, and from 20 to 30 minutes during 30 mm of Hg pressure. Tidal volume decreased from 5 to 30 minutes during 10 and 20 mm of Hg pressures, and from 5 to 40 minutes during 30 mm of Hg pressure. Minute ventilation decreased at 10 and 20 minutes during 20 mm of Hg pressure. End-tidal CO2 concentration increased from 5 to 30 minutes during 20 and 30 mm of Hg pressure. The PaCO2 decreased at 40 minutes during 10 mm of Hg pressure, at 30 minutes during 20 mm of Hg pressure, and from 10 to 40 minutes during 30 mm of Hg pressure. Values for pH decreased from 10 to 30 minutes during 20 and 30 mm of Hg pressures. The PaO2 decreased from 20 to 40 minutes during 10 mm of Hg pressure, at 30 minutes during 20 mm of Hg pressure, and from 10 to 40 minutes during 30 mm of Hg pressure. Percentage decrease in tidal volume was greater at 5 and 15 minutes with 30 mm of Hg pressure. Differences in percentage increase in end tidal CO2 concentration were observed among the 3 pressures from 5 to 30 minutes. Although significant, these changes do not preclude use of laparoscopy if insufflation pressure > 20 mm of Hg is avoided.

Six Salmonella enteritidis bacterin formulations differing in adjuvant content and whole-cell inactivation procedures were evaluated in egg-laying chickens. Chickens given S. enteritidis bacterins containing modified Freund's incomplete adjuvant had greater humoral immune responses to S. enteritidis than did birds given other bacterin formulations (P < 0.05). Better protection against infection by S enteritidis phage types 8, 13a, and 23 was obtained in birds vaccinated with bacterin 5. Bacterin 5 contained S. enteritidis cells inactivated by 20% acetone and modified Freund's incomplete adjuvant.

Pharmacokinetic determinants of danofloxacin (1.25 mg/kg of body weight, IV) and its penetration into the respiratory tract tissues were studied in sixteen 4- to 6-week-old calves. The disposition curve was best described by an open 3-compartment model. Mean elimination half-life was 7.4 hours and the steady-state volume of distribution was 4.3 L/kg. The large volume of distribution was confirmed by a rapid and high penetration of the drug into respiratory tract tissues and secretions. In all structures (lung tissue, bronchial mucosa, bronchial secretions, and nasal secretions), danofloxacin concentration peaked 1 hour after drug administration. The area under the curve ratio for concentrations in tissue or secretions to concentrations in plasma was approximately 5 for lung tissue, 3 for bronchial mucosa, 0.85 for bronchial secretions, and 0.42 for nasal secretions. Protein binding of danofloxacin was 49% in plasma, 31% in bronchial secretions, and 14% in nasal secretions, resulting in consistently higher free danoflaxacin concentrations in bronchial secretions than in plasma. Accumulation of danofloxacin within bronchial mucosa and the high concentration of free drug in bronchial secretions suggested that an active process may be involved in the transport of danofloxacin across the airway epithelium. The dose of danofloxacin administered provided drug concentrations above the minimal inhibitory concentration of common respiratory pathogens for up to 12 hours in bronchial mucosa, up to 8 hours in bronchial secretions, and up to 4 hours in nasal secretions.

To determine blood supply in the area, dye or radioopaque contrast material was injected into the named arteries supplying the terminal colon and rectum in 10 dogs. The cranial rectal artery appeared to supply most of the blood to the terminal colon and rectum. The middle and caudal rectal arteries supplied variable and relatively insignificant amounts. The intrapelvic rectum had a less adequate blood supply than did the terminal colon or proximal rectum. A ventral midline laparotomy and pubic osteotomy were performed in an additional 11 dogs to provide access to the terminal colon and rectum. When the cranial rectal artery was ligated and the colorectal junction was transected and anastomosed, the intrapelvic rectum developed marked congestion, edema, and discoloration. Rectal fluorescence, after IV administration of fluorescein, was either poor or absent. Histologically, partial- to full-thickness mucosal necrosis was evident in most tissue specimens taken from the rectum, and muscle necrosis was evident in some. These findings suggest that, in dogs, the cranial rectal artery should be preserved if at all possible and, if the cranial rectal artery is ligated, most of the intrapelvic rectum should be resected to ensure adequate blood supply to the anastomosis.

A study was performed to determine whether experimentally induced bovine leukemia virus (BLV) infection in cattle could be detected earlier by use of polymerase chain reaction (PCR) amplification of genomic DNA extracted from leukocytes than by use of conventional agar-gel immunodiffusion (AGID). The PCR primers were designed to amplify a 375-basepair region of the proviral gag gene. Five cows were identified that were BLV-negative on the basis of AGID and PCR results. At day 0, these cows were inoculated IM with blood pooled from 3 naturally infected cows. Blood samples were taken on days 0, 1, and 7, and every 2 weeks thereafter until 3 months after inoculation. Three of the cows were BLV-positive by AGID test results 3 weeks after inoculation, and the remaining 2 seroconverted at 5 weeks. In contrast, all 5 cows were BLV-positive by PCR results 7 days after inoculation and remained positive for the duration of the study. Five cows that were BLV-positive by AGID test and PCR results on day 0 and from which samples were obtained at the same times as those from the other 5 cows, remained BLV-positive by results of both tests during the course of the study. Results indicate that under experimental conditions, BLV infection in cattle can be detected as much as 2 to 4 weeks earlier by use of PCR than by use of the AGID test.

Tissue specimens and serum samples obtained from adult budgerigars in various stages of reproduction housed in an aviary with enzootic avian polyomavirus (APV) disease were examined by means of polymerase chain reaction techniques for APV DNA. Although the birds were apparently healthy, APV DNA could be detected in all 40 birds examined (inapparent infection rate, 100%). Viral DNA was found in most organ systems examined. Analysis of data suggested that organ virus concentrations were lower in breeding than in nonbreeding birds. Serum samples from 144 birds were examined for virus-neutralizing (VN) antibody. All serum samples had detectable VN antibody titers. Determining VN titer had a sensitivity of 100% for detection of APV infection in birds and was more sensitive than analysis of droppings by use of polymerase chain reaction techniques to detect APV infection in 6-month-old birds. Analysis of the data suggested that lower VN antibody titers were associated with longer duration of continuous breeding.