The cause of species difference in the susceptibility of erythrocytes to L-sorbose, and the difference in the hemolytic effect of sorbose on high potassium-containing (HK) and low potassium-containing (LK) canine erythrocytes were examined. L-sorbose was phosphorylated in canine erythrocytes, but not in human erythrocytes. Furthermore, sorbose-1-phosphate, a metabolite of L-sorbose, strongly inhibited the hexokinase of LK canine erythrocytes, but not that of HK canine erythrocytes. These results strongly indicated that inhibition of hexokinase by sorbose-1-phosphate in LK erythrocytes induced severe glycolytic limitation in these cells, resulting in hemolysis, and that HK erythrocytes are resistant to sorbose-induced hemolysis because these cells have a high hexokinase activity.

An applanation tonometer was used to estimate intraocular pressure in normal eyes of several species of raptors. No bird had active injury or illness, though some were nonreleasable to the wild because of previous injury. Mean (+/- SD) intraocular pressure was 20.6 (+/- 3.4) mm of Hg in red-tailed hawks (Buteo jamaicensis, n = 10), 20.8 (+/- 2.3) mm of Hg in Swainson's hawks (Buteo swainsoni, n = 6), 21.5 (+/- 3.0) mm of Hg in golden eagles (Aquila chrysaetos, n = 7), 20.6 (+/- 2.0) mm of Hg in bald eagles (Haliaeetus leucocephalus, n = 3), and 10.8 (+/- 3.6) mm of Hg in great horned owls (Bubo virginianus, n = 6). There was no significant difference in intraocular pressure between hawks and eagles. Mean pressure in great horned owls was significantly (P < 0.01) lower than pressure in hawks or eagles. Reliable intraocular pressure readings could not be obtained in barn owls (Tyto alba).

Plasma disposition and urinary recovery of sulfamethazine (SMZ), its N4-acetylated metabolite (N4AcSMZ), and 2 of its hydroxylated metabolites--5-hydroxysulfamethazine 5OHSMZ) and 6-hydroxymethylsulfamethazine (6CH2OHSMZ)--were determined in either sex of 4 animal species: rats, dwarf goats, rabbits, and cattle. Rats, rabbits, and dwarf goats had significant (P < 0.01) sex difference in SMZ plasma clearance. Male rats had higher plasma clearance than did female rats, and excreted higher amounts of the hydroxy metabolites and lower amounts of N4AcSMZ. The N4AcSMZ metabolite was predominant in plasma and urine of rabbits. Male rabbits had higher plasma clearance than did female rabbits, but differences in metabolite profile were not apparent. With regard to plasma SMZ elimination, the situation in goats was opposite to that in rats. Male goats had considerably lower clearance than did female goats. This was associated with a lower hydroxylation rate in males. Plasma half-life of SMZ in cows was lower than that in bulls, probably because of a smaller distribution volume in cows. Compared with elimination via urine, elimination via milk was negligible in cows. Significant differences in metabolite profiles were not found between bulls and cows. Similar to those in rats and mice, hormone-dependent xenobiotic metabolic pathways may exist in other species. Depending on species and xenobiotic compound residue concentrations of xenobiotics, their metabolites, or both may differ with sex of the animal, or may be altered after treatment with anabolic hormones.

Isoelectric focusing was performed on the soluble proteins of whole-body and excretory-secretory products (ESP) of Fasciola hepatica and Fascioloides magna. Adult F hepatica flukes were recovered from experimentally infected sheep and ESP obtained from the flukes; portions of liver were cut and frozen at -70 C. Fascioloides magna adults were collected from naturally infected white-tailed deer and ESP obtained; portions of liver were collected from noninfected white-tailed deer. Adult flukes and their host tissues were homogenized and centrifuged; protein concentrations with their ESP were determined and adjusted to < 2.50 mg/ml. Seven ESP samples from F hepatica and 1 from Fascioloides magna were subjected to isoelectric focusing with the 2 species of fluke and their respective host liver homogenates. After separation, gels were stained with silver and scanned on a laser densitometer. Protein banding patterns of the 2 species of flukes were dissimilar. In the pH range of 3.5 to 9.6, the body protein had approximately 30 peaks and ESP about 23 peaks in both species. Overall banding patterns of the body protein and ESP of both species were distinct from those of respective host tissues. Of the peaks reported as dominant, 3 of the body protein and 2 of ESP were shared between the 2 species. Fascioloides magna had more dominant peaks than F hepatica. This technique of soluble protein isoelectric focusing is simple and reproducible, and the 2 fluke species can easily be differentiated by this technique, as well as by morphologic characteristics.

The central arterial pharmacokinetics of alfentanil, a short-acting opioid agonist, were studied in rabbits, sheep, and dogs after short-duration infusion of the drug. Alfentanil was infused until a set end point (high-amplitude, slow-wave activity on the EEG) was reached. This required a larger alfentanil dose and a higher alfentanil arterial concentration in sheep, compared with rabbits and dogs. The plasma concentration-time data for each animal were fitted, using nonlinear regression, and in all animals, were best described by use of a triexponential function. In this study, differences in the disposition kinetics of alfentanil among the 3 species were found for only distribution clearance and initial distribution half-life. In dogs, compared with rabbits and sheep, the first distribution half-life was longer, probably because of pronounced drug-induced bradycardia (mean +/- SD, 48 +/- 21 beats/min). Distribution clearance was faster in sheep, compared with dogs, also probably because of better blood flow in sheep. Elimination half-life was similar in all species (rabbits, 62.4 +/- 11.3 minutes; sheep, 65.1 +/- 27.1 minutes; dogs, 58.3 +/- 10.3 minutes). This rapid half-life resulted from a small steady-state volume of distribution (rabbits, 908.3 +/- 269.0 ml/kg; sheep, 720.0 +/- 306.7 ml/kg; dogs, 597.7 +/- 290.2 ml/kg) and rapid systemic clearance (rabbits, 19.4 +/- 5.3 ml/min/kg; sheep, 13.3 +/- 3.0 ml/min/kg; dogs, 18.7 +/- 7.5 ml/min/kg). On the basis of these pharmacokinetic variables, alfentanil should have short duration of action in rabbits, sheep, and dogs. This may be beneficial in veterinary practice where rapid recovery would be expected after bolus administration for short procedures or after infusion for longer procedures.

The assessment of cutaneous microcirculation by laser-Doppler velocimetry (LDV) has been primarily limited to human studies. The purpose of this investigation was to establish normal values in various species and anatomic sites for blood flow, velocity, and volume as determined by LDV. Microcirculation was measured with a laser-Doppler velocimeter in 54 animals, 6 healthy animals from each of 9 species. The standard sites used were the buttocks, convex surface of the ear, metacarpal pad, humeroscapular junction, thoracolumbar junction, ventral portion of the abdomen, dorsal metacarpus (hooved animals), and ventral surface of the tail (horse). Significant differences in blood flow, velocity, and volume were measured between species and sites within species. The ventral portion of the abdomen consistently had the highest relative blood flow across all species except the monkey. Measurements in the canine metacarpal pad had a high SD, possibly indicating the stratum corneum and epidermis to be too thick for LDV. Our findings provide baseline data in several species, with application of LDV in comparative dermatologic research.

The Escherichia coli heat-stable enterotoxin (STb) is the most prevalent toxin associated with diarrheagenic E coli isolates of porcine origin. Unequivocal biological activity of this toxin has been observed only in swine intestine. In this study, when endogenous protease activity was blocked with soybean trypsin inhibitor, intestinal secretion was stimulated by STb in jejunal loops of rats, mice, calves, and rabbits. Compared with pigs, rats, mice, and calves, rabbits were relatively insensitive to STb. These data demonstrate that the activity of STb is not a species-specific toxic activity; there is species variation in sensitivity to STb, and some common laboratory animals may have potential to be used to measure biological activity Of STb.

To provide information about oncogenes for molecular biological studies of tumors in domestic animals, theproto-oncogenes homologous to the c-myc, c-erbB-2, c-ros-1, c-yes-1, v-myc, v-Ki-ras, and v-Ha-ras oncogenes of genomic DNA in cattle, horses, pigs, dogs, cats, and chickens were investigated by Southern blot hybridization. High molecular weight genomic DNA in each of the animals contained proto-oncogenes that had a certain homology with the oncogenes used, but the extent of nucleotide homology of the proto-oncogenes differed in number and molecular weight: ie, 1 or 2 bands at 1.6 to 22.0 kilobase (kb) in the c-myc probe, 1 or 2 bands at 1.1 to 16.0 kb in the c-ros-1 probe, 1 to 3 bands at 0.7 to 23.0 kb in the c-erbB-2 probe, 1 to 4 bands at 0.6 to 18.0 kb in the c-yes-1 probe, 1 to 3 bands at 1.6 to 30.0 kb in the v-myc probe, 1 to 7 bands at 1.0 to 36.0 kb in the v-Ki-ras probe, and 1 to 4 bands at 1.0 to 27.0 kb in the v-Ha-ras probe. Furthermore, signal strength of each band, as determined by autoradiography, was not always the same for each probe in the various animals. Our findings indicate that these proto-oncogenes are well conserved with species specificities in each animal.

Restriction endonuclease patterns of genomic fragments separated by use of pulsed-field gel electrophoresis were used to differentiate Brucella abortus strain RB51, a rifampin-resistant mutant of the standard virulent strain 2308, from other brucellae. Results were compared with results obtained by use of standard methods for characterizing brucellae. Electrophoretic patterns of the ATCC type strains allowed identification of the strains to the level of species. Genomic profiles of B abortus biovars 1, 2, and 4 were similar, as were those of biovars 5, 6, and 9. The profile of biovar 3 was similar to that of biovars 5, 6, and 9, except for a missing band at 93 kb and additional bands at 65 and 67 kb. A different fingerprint was detected in B abortus strain RB51, using the pulsed-field gel electrophoresis patterns of genomic DNA digested with restrictive endonuclease Xba I. The profile of B abortus strain RB51 contained a band at 104 kb, as opposed to a 109-kb fragment within profiles of B abortus isolates from naturally infected cattle, bison, and elk. Despite known biochemical and biological differences between RB51 and its parent strain (2308), restriction endonuclease analysis results were similar.

The metabolic responses of equine articular cartilage to incubation with bacterial lipopolysaccharide (LPS) were studied, using explant cultures of articular cartilage obtained from the metatarsophalangeal joints of 15 horses, age of which ranged from 3 months to 20 years. For comparison, explants were also established from the metatarsophalangeal joints of 3 calves. Explants were cultured for 3 days in medium containing various concentrations of LPS from 0 (control) to 100 microgram/ml. Glycosaminoglycan (GAG) released during the 3-day incubation was determined by a spectrophotometric assay, using the dye 1,9-dimethylmethylene blue. Newly synthesized GAG content was assayed by measuring [35S]sulfate incorporation during a 3-hour pulse labeling period. In addition, prostaglandin E2 (PGE2) synthesis was quantified, using a [3H]PGE2 radioimmunoassay kit and magnetic separation. Finally, explants from 3 animals were used to evaluate the effect of supplementing culture medium with 5% serum on the response of explants to LPS, and explants from 1 horse were used to compare responses to stimulation with LPS derived from 2 bacterial sources. Equine explants cultured with bacterial LPS had a dose-dependent decrease in synthesis and increase in release of GAG, and these responses were significantly (P < 0.0001) greater in explants from younger horses. In addition, equine explants had a significant (P = 0.0001) dose-dependent increase in concentration of PGE2 released into the culture medium in response to incubation with LPS. Comparison of data for GAG synthesis from equine and bovine explants revealed a significant (P = 0.025) difference in responsiveness to LPS between the 2 species. Equine explants tended to have a greater suppression of GAG synthesis in response to incubation with increasing concentrations of LPS than did age-corrected bovine samples. However, similar analysis of data on GAG release did not indicate any difference in sensitivity between the 2 species for this response. There was no evidence that the presence or absence of serum supplementation or the use of LPS derived from different bacterial sources made a significant difference in the response of explants to incubation with LPS.