The absorption kinetics and glycemic effects of 3 long-acting insulin preparations (protamine zinc beef-pork insulin, ultralente beef-pork insulin, and ultralente human insulin) were evaluated in 9 healthy, adult, domestic shorthair cats (6 males, 3 females). A triple crossover study was performed, in which the serial serum concentrations of insulin and glucose were determined over a 24-hour period after sc administration of the 3 insulin preparations (dosage, 1.0 U/kg of body weight) at 3-week intervals. A control study was also performed in 4 of the cats by serially collecting samples for insulin and glucose determinations after administration of insulin diluent. After administration of protamine zinc insulin (PZI), mean (+/- SEM) serum insulin concentration increased significantly (P < 0.05) above baseline, reached a peak value (484 +/- 287 pmol/L) at 1 hour, and remained significantly (P < 0.05) higher than baseline at 24 hours. After administration of ultralente human insulin, the serum insulin curve was similar to that obtained after PZI administration, but mean serum insulin concentration took longer to peak (538 +/- 177 pmol/L at 4 hours). After administration of ultralente beef-pork insulin, mean peak serum insulin concentration was lower (220 +/- 54 pmol/L, not statistically significant) than that obtained after administration of PZI and ultralente human insulins; it then decreased to values statistically indistinguishable from baseline by 16 hours. The area under the serum insulin concentration curve for PZI (5,063 +/- 681 pmol.h/L) and ultralente human insulin (4,138 +/- 439 pmol.h/L) was significantly (P < 0.05) larger than that for ultralente beef-pork insulin (2,378 +/- 561 pmol.h/L). Serum glucose concentration decreased after administration of all 3 insulins, but the decrease was not different from that observed after diluent (control) administration. Results of this study indicate that differences may exist between absorption of PZI, ultralente human, and ultralente beef-pork insulins. Of the 2 ultralente insulin preparations, human insulin appears better absorbed than beef-pork insulin, but these findings need to be confirmed in cats with naturally acquired diabetes mellitus.

Diamine oxidase (DAO), an enzyme of small intestinal origin, is released from mucosal storage sites by IV administration of heparin, to yield the plasma postheparin DAO (PHD) curve. The PHD curve is diminished when mucosal surface area is lost, and baseline (without heparin) plasma DAO activity increases when mucosal storage sites are damaged. Plasma DAO activity was measured after 2 doses of heparin were administered Iv in healthy, conscious horses. In anesthetized horses, the PHD curve was studied: during sham small intestinal surgery, and during venous strangulation obstruction (VSO) of the distal 50% of the small intestine. In a third group of anesthetized horses, baseline plasma DAO activity (without heparin) was measured during vso of the distal 50% of the small intestine for 90 minutes, followed by reperfusion for 90 minutes. Postheparin plasma DAO curves in conscious horses were similar to those reported in other species Horses with VSO had a similar PHD curve as did sham-operated controls at all times, except at 15 minutes, when plasma DAO activity was significantly (P < 0.05) greater in the vso group. Horses with VSO and reperfusion had no change in baseline plasma DAO activity throughout the study. Peritoneal fluid DAO activity remained low throughout the study, but increased slightly in horses with VSO that received heparin, possibly because of DAO from extravasated blood in the peritoneal fluid. Results indicated that the plasma DAO response to IV administered heparin in horses is similar to that in other mammals, but, unlike other species, baseline and postheparin DAO activities did not change as expected after small intestinal vascular obstruction and mucosal injury. There may be additional sources of DAO in horses, the type of injury induced was not of sufficient magnitude to affect storage sites of DAO, or the circulatory changes induced by vso might have altered tissue delivery of heparin.

Polymorphonuclear neutrophils (PMN) from 4 cows were preincubated (30 minutes, 37 C) in either actinomycin D (100 micrograms/ml) or puromycin (10 micrograms/ml), inhibitors of mRNA transcription and protein translation, or in medium 199. The PMN were incubated for a further 4.5 hours in medium containing 100 U of recombinant bovine interferon-gamma (rboIfn-gamma). The PMN were then incubated with bovine IgG1, IgG2, IgM, or aggregated IgG (aIgG; 4 C, 12 hours) for flow cytometric analysis, using fluoresceinated isotype-specific antibody. The percentage of PMN binding the ligand and the logarithmic mean fluorescent channel (LMFC), an indicator of the amount of receptor (R) expression, were recorded. Competitive inhibition of ligand binding was measured by incubating PMN with fluoresceinated IgG2 in the presence or absence of 100-fold excess of IgG1, IgG2, and aIgG. Activation with rboIfn-gamma induced a 4.5-fold increase in binding of IgG1 and a fivefold increase in LMFC for IgG2. These increases were inhibited by actinomycin D and puromycin. Percentage of PMN binding aIgG decreased after activation by rboIfn-gamma. Interferon-gamma treatment did not affect binding or LMFC of IgM. However, binding of IgM was reduced by treatment with actinomycin D. Binding of fluoresceinated IgG2 was inhibited by unlabeled IgG1, IgG2, and aIgG. Results indicate that bovine PMN Fc receptors (FcR) for IgG1 and IgG2 were rboIfn-gamma inducible, that induction required de novo transcription and translation, that a heterogeneous population of FcR exist on bovine PMN, and that IgG1 and IgG2 share a common FcR. Further, bovine PMN are capable of gene activation and are responsive to changes in their environment, thus being amenable to modulation for effective pathogen destruction.

Force platform analysis of gait provides ground reaction force information that can be used to study limbs with normal or abnormal function. When combined, the interrelated variables of ground reaction forces give a more thorough description of gait than when used individually. To describe the pattern of ground reaction forces in clinically normal, conditioned, mesomorphic dogs, we studied the data from platform gait analyses of 43 dogs. Mediolateral (Fx), craniocaudal (Fy), and vertical (Fz) forces were measured and recorded. Torque (Tz) around the vertical axis also was calculated. Mean stance times for forelimbs and hind limbs were 0.278 and 0.261 second, respectively. Among dogs, ground reaction forces were normalized and expressed as percentage of body weight (%bw). The vertical (Fz) peak, average force during stance phase, and force vs time impulses were 106.68, 60.82, and 17.2 %bw in forelimbs, and were 65.11, 35.3, and 9.33 %bw in hind limbs. The forelimb braking/ propulsive (Fy) peaks were -16.74 and +6,73 %bw. In hind limbs, these peaks were -3.76 and +7.69 %bw. The usual mediolateral force (Fx) pattern found in forelimbs was laterally directed, with average peak magnitude of 6.69 %bw, whereas the hind limb patterns were variable.

Although healthy and diseased bovine respiratory tracts have been intensively studied during the last years, to the authors' knowledge, there have been no attempts to objectively examine the inspiratory drive from the brain to the nerves and muscles and its transformation in pressure. Such technique would be useful in assessing the possibility of altered ventilatory drive or inspiratory muscle fatigue in the context of an animal with ventilatory failure. The relation among ventilation, airway opening occlusion pressure generated 100 milliseconds after onset of inspiration (Pawo100ms) and 6 indexes describing diaphragmatic electromyographic activity (EMGdi) recorded via implanted fishhooks was evaluated during free and impeded CO2, rebreathing in 6 young bulls. The best significant linear correlations (r > 0.8) with inspiratory center afferent stimulation, as judged by end-tidal CO2 concentration in expired air, were found for Pawo100ms, peak moving time average or variance EMGdi, and mean integrated EMGdi, whatever had been the respiratory impedance. However, with an inspiratory load, Pawo100ms responses systematically had greater increase for a given change in the driving EMGdi, implying dependence of the former not only on neural input, but also on configurational factors that determine inspiratory muscle excitation-pressure generation couplings. The reproducibility of EMGdi absolute values and changes was satisfactory up to 10 hours, but could not be repeated from one day to the other. It was concluded that, provided the constancy of the electrical coupling of the recording system to the tissue being studied is ensured, specific EMGdi and Pawo100ms values correlate reliably with amount of CO2 during free and loaded breathing. Simultaneous collection of both values during experimentally induced pulmonary disease in calves could, therefore, produce information to help answer questions about the role of CNS and inspiratory muscle dysfunction in case of ventilatory failure. Careful interpretation, however, requires additional measurements, such as end-expiratory lung volume, and some familiarity with the underlying physiologic processes that link phrenic nerve discharge to generation of negative pressure at the airway opening.

Axial stability of equine oblique proxidmal phalangeal osteotonies with application of the standard short limb cast or 1 of 3 configurations of transfixation casts was determined in vitro. Transfixation cast methods included use of parallel pins, divergent pins, or parallel pins incorporating a metal walking bar. Displacement at the osteotomy was recorded for each limb at 4,448 N. Standard short limb casts provided significantly (P = 0.0002) less axial stability than did any form of transfixation cast. Significant differences were not found between the 3 transfixation casts.

Placental transfer of enrofloxacin and ciprofloxacin was evaluated, using a rabbit in situ perfusion model. A two-step infusion program was carried out to obtain steady-state maternal plasma concentrations of these drugs. For each compound, the placenta in 5 rabbits was perfused for 200 minutes with Earle's enriched bicarbonate buffer at flow rate of 1.5 ml/min. To assess reliability of the model, most of the determinants of placental transfer (maternal and fetal pH, gas balance, heart status, rectal temperature, and protein binding) were controlled. In addition, the infusion program included administration of antipyrine, a commonly used indicator of placental exchange. Drug concentrations were measured in maternal plasma and perfusate by use of a high-performance liquid chromatographic assay. Plasma protein-binding estimation indicated no differences between the drugs. Placental clearance of the drugs was significantly (P < 0.01) different (0.88 +/- 0.13 ml/min for enrofloxacin and 0.06 +/- 0.02 ml/min for ciprofloxacin). These values accounted for 81 and 5%, respectively, of the placental clearance found for antipyrine. These results indicate that caution must be taken when enrofloxacin is to be used during pregnancy, and suggest the need to extend this type of experiment to species that can be exposed to these drugs used for therapeutic or prophylactic purposes.

Breaking strength (torque at failure) of equine third metacarpal bones, with transfixation pins placed parallel in the frontal plane and 30 degrees divergent from the frontal plane, was determined in vitro. Two transfixation pins were placed through the distal metaphysis, using a jig designed to drill the holes in the assigned configuration. Paired metacarpal bones II through IV from 12 horses were tested in torsion. The torsional moment of the force applied through the transfixation pins at failure was compared for each limb. Metacarpal bones with divergent pins were significantly (P = 0.030) stronger, compared with those with parallel pins. Metacarpal bones with parallel pins failed with longitudinal oblique fractures through a proxidmal bone-pin interface, whereas those with divergent pins failed with more comminuted fractures through multiple bone-pin interfaces.

The left ovary of chicken embryos was removed and incubated in culture medium with a thymidine analogue, bromodeoxyuridine (BrdU), in vitro. In addition, fertile chicken eggs were injected with BrdU via the extraembryonic vessels and incubated for 24 hours. The ovaries were then processed for immunohistochemical localization of calbindin-D28K (a 28-kd vitamin D-dependent calcium-binding protein) and BrdU. Calbindin-D28K was detected in the germinal epithelium and in cells surrounding the oogonia and oocytes (future granulosa cells) of the embryonic chicken ovary. However, Brdu was observed in the nucleus of the oogonia and oocytes of the chicken embryonic ovaries. Comparison of the 2 adjacent sections, immunostained for calbindin-D28K and BrdU consecutively, indicated that BrdU, the marker for cell proliferation was not detected in calbindin-D28K-containing cells, namely, germinal epithelium and future granulosa cells, in the ovary of chicken embryos. These results suggested that calbindin-D28K-containing cells in the ovary were not in the process of cell division during the 24-hour incubation of chicken embryos.

Thirty-two mixed-breed male and female cats were blocked by sex, arranged by body weight from greatest to least, and allocated to 4 groups of 8 (4 male, 4 female) cats, using random numbers. Cats in each of 3 groups were treated orally with a 7% suspension formulation of lufenuron at dosage of 15, 30, or 45 mg/kg of body weight. Cats in the fourth group were treated orally with an excipient suspension without lufenuron. Cats were infested with newly emerged, unfed cat fleas (Ctenocephalides felis felis) on days -7 and -3 before treatment and at approximately weekly intervals after treatment. Flea eggs were collected from beneath each cat on selected days before and after treatment and placed in an artificial rearing medium. Flea eggs and medium were kept for 35 days in an insectary to determine effects of lufenuron or excipient suspension on emergence of adults of the F1 generation. Lufenuron was 100% effective in inhibiting development of C felis at all dosages for 11 days after treatment. Thereafter, efficacy exceeded 92% in all dosages groups, On day 32, when the study was terminated, efficacy for each of the dosage groups was: 15 mg/kg, 95.2%; 30 mg/kg, 98.2%; and 45 mg/kg, 99.6%. Adverse reactions or side effects were not observed in cats, regardless of treatment dosage.