The effect of bethanechol, neostigmine, metoclopramide, and propranolol on myoelectric activity of the ileum, cecum, and proximal loop of the ascending colon was determined in 6 healthy Jersey cows implanted with 8 pairs of bipolar electrodes. Assigned at random, each cow received each of 5 treatments in 3-day intervals. The treatments included bethanechol (0.07 mg/kg of body weight, SC), neostigmine (0.02 mg/kg, SC), metoclopramide (0.15 mg/kg, IM), DL-propranolol (0.2 mg/kg, IM), and 0.9% sodium chloride (NaCl) solution (20 ml, SC). All drugs were administered during early phase I of the migrating myoelectric complex in the ileum. Myoelectric activity was recorded for 4 hours after treatment, and data were analyzed for each hour separately. Bethanechol and neostigmine significantly (P < 0.05) increased the number of cecocolic spikes per minute per electrode, duration of cecocolic spike activity (%), and number of cecocolic propagated spike sequences per 10 minutes, relative to NaCI, during 1 or more hours of the recording period. The effect of bethanechol was more pronounced on duration of spike activity and number of propagated spike sequences, whereas neostigmine mainly increased the number of (uncoordinated) spikes. Metoclopramide and propranolol had no significant effect on cecocolic myoelectric activity, relative to NaCl. It was concluded that bethanechol and, less likely, neostigmine at the dosage used in this study may be suitable for medical treatment of cecal dilatation in cattle in which hypomotility of the cecum and proximal loop of the ascending colon has to be reversed. The potential advantage of bethanechol vs neostigmine for medical treatment of cecal dilatation is worth further evaluation.

The alpha 1-proteinase inhibitors of trypsin, Spi1, Spi3A, and Spi3B, in bronchoalveolar lavage fluid (BALF) and serum of horses were separated by electrophoresis, and their proportions were quantified in 12 control horses and 12 with chronic obstructive pulmonary disease (COPD). A significantly lower proportion of Spi3B (P < 0.05) and higher proportion of Spi1 (P < 0.02 to P < 0.01) were detected in BALF, compared with serum, in control and COPD-affected horses and appeared to be attributable to reduced Spi3 activity in BALF. There was no significant difference between the control and COPD groups in this respect, indicating that the decrease in Spi3 may be a physiologic phenomenon. The differences observed may be associated with proteolytic damage to or preferential complex formation by Spi3.

Efficacy of sulbactam, a beta-lactamase inhibitor, in combination with ampicillin, was evaluated for treatment of experimentally induced pneumonia caused by beta-lactam-resistant Klebsiella pneumoniae. Infection was experimentally induced in 18 healthy weanling foals that were randomly allocated to 3 treatment groups: sulbactam plus ampicillin (S/A, 3.3 and 6.6 mg/kg of body weight, respectively), ampicillin (6.6 mg/kg), or vehicle only. Foals were treated daily for 7 days; the observer was unaware of treatment status. Compared with ampicillin and vehicle, treatment with S/A resulted in a statistically significant (P < 0.05) decrease in severity of pneumonia, with regard to bronchoalveolar lavage cytologic findings (decreased total cell and neutrophil numbers, and increased lymphocyte numbers) and extent of macroscopic lesions in lung tissue of the noninoculated regions. Marked trends toward improvement of S/A-treated foals were observed for quantitative results of bacteriologic culture of bronchoalveolar lavage fluid samples (P < 0.07), macroscopic pathologic features of the whole lung (P < 0.1), and histopathologic variables (P < 0.07), compared with ampicillin- and vehicle-treated foals. Treatment effects were not observed for radiographic, hematologic, and blood gas abnormalities that resulted from infection. In conclusion, the combination of sulbactam plus ampicillin was found to have synergistic effects in vivo, to reduce the extent and severity of experimentally induced grain-negative lung infection in foals.

To determine the role of thromboxane A2 in the pathogenesis of experimentally induced immune complex glomerulonephritis, 12 concanavalin A-immunized Beagles were infused with 1 mg of concanavalin A via each renal artery and treated twice daily for 8 days with either 30 mg of CGS 12970/kg, PO, a specific thromboxane synthetase inhibitor, or placebo. The effect of treatment was assessed by measuring endogenous creatinine clearance and urine protein and eicosanoid excretion, and by evaluating changes in glomerular morphometric characteristics. On postinfusion day 8, urine protein, thromboxane B2, and 11-dehydro-thromboxane B2 excretion, glomerular epithelial crescent formation, and glomerular cell proliferation in the CGS 12970-treated dogs were significantly decreased when compared with values in the placebo-treated group. Differences were not observed in endogenous creatinine clearance, urine prostaglandin E2 and 6-keto-prostaglandin F1 alpha excretion, or glomerular polymorphonuclear leukocyte infiltration between groups in this study. These findings suggest thromboxane A2 has a role in the development of immune complex glomerulonephritis and that thromboxane synthetase inhibition may be beneficial in attenuating some of the functional and histologic changes associated with immune complex glomerulonephritis.

OBJECTIVE To develop and validate a sandwich ELISA for the measurement of α1-proteinase inhibitor (α1-PI) concentrations in serum and fecal samples obtained from common marmosets (Callithrix jacchus). SAMPLE Leftover serum (n = 42) and fecal (23) samples submitted for diagnostic testing; paired serum and fecal samples obtained from 30 common marmosets at 2 research colonies. PROCEDURES A sandwich ELISA was developed and analytically validated by determining the lower limit of detection, linearity, accuracy, precision, and reproducibility. Reference intervals for α1-PI concentrations in serum and feces of common marmosets were calculated. RESULTS The standard curve was generated for concentrations between 1 and 100 ng/mL. Mean ± SD observed-to-expected ratio for serial dilutions of serum and fecal samples was 117.1 ± 5.6% (range, 112.2% to 123.0%) and 106.1 ± 19.7% (range, 82.6% to 130.2%), respectively. Mean observed-to-expected ratio for spiking recovery of serum and fecal samples was 102.9 ± 12.1% (range, 86.8% to 115.8%) and 97.9 ± 19.0% (range, 83.0% to 125.1%), respectively. Reference interval for serum concentrations of α1-PI was 1,254 to 1,813 μg/mL, for 3-day mean fecal concentrations was 11.5 to 42.2 μg/g of feces, and for 3-day maximum fecal concentrations was 13.2 to 51.2 μg/g of feces. CONCLUSIONS AND CLINICAL RELEVANCE The ELISA was linear, accurate, precise, and reproducible for quantification of α1-PI concentrations in serum and feces of common marmosets. However, the ELISA had limited linearity and accuracy for spiking recovery of fecal samples.

Objective-To compare cytotoxic effects and antiviral efficacy of 9 nucleoside reverse transcriptase inhibitors (NRTIs) against FIV in feline peripheral blood mononuclear cells. Sample-Peripheral blood mononuclear cells obtained from 3 specific pathogen-free cats. Procedures-3 of the 9 NRTIs had not been previously assessed in feline cell lines. Cytotoxic effects were determined by colorimetric quantification of a formazan product resulting from bioreduction of a tetrazolium reagent by viable peripheral blood mononuclear cells; uninfected cells from 1 cat were used in these assays. Cells from all 3 cats were infected with a pathogenic clone of FIV, and in vitro antiviral efficacy of each NRTI was assessed with an FIV p24 antigen capture ELISA. Results-Cytotoxic effects in feline peripheral blood mononuclear cells were observed only at concentrations > 10 μM for all 9 NRTIs. Comparison of the cytotoxic effect at the highest concentration investigated (500μM) revealed that didanosine and amdoxovir were significantly less toxic than abacavir. All drugs induced a dose-dependent reduction of FIV replication. At the highest concentration investigated (10μM), there was no significant difference in antiviral efficacy among the test compounds. Conclusions and Clinical Relevance-The evaluated NRTIs had low cytotoxicity against feline peripheral blood mononuclear cells and appeared to be safe options for further in vivo evaluation for the treatment of FIV-infected cats. There was no evidence suggesting that the newly evaluated compounds would be superior to the existing NRTIs for reducing FIV burden of infected cats.

Objective--To test the hypothesis that endothelium-derived nitric oxide modulates vasomotor reactivity in equine digital arteries. Design--Digital arteries were isolated from adult horses, and their vasodilator properties were examined in an in vitro controlled environment. Animals--Five adult horses (1 gelding, 4 mares) without evidence of hoof or vascular disease were studied. Procedure--Arterial rings with or without endothelium were exposed to endothelium-dependent vasodilator drugs in the presence or absence of a pharmacologic inhibitor of the enzyme nitric oxide synthase. Results--Vasodilator effects of 3 endothelium-dependent vasorelaxant agents were significantly greater in endothelium-intact vessels than in endothelium-denuded vessels. Moreover a nitric oxide synthase inhibitor reduced vasodilator responses to endothelium-dependent vasodilators in endothelium-intact arteries, but had no discernable effects in endothelium-denuded arteries. Conclusions--These findings indicate the presence of endothelium-derived relaxing factor/nitric oxide in blood vessels of horses, and identify vascular endothelium as an endogenous modulator of vasomotor tone in the digital arteries of this species.

A repeated-measures study was conducted on 5 dogs to clinically, radiographically, and echocardiographically characterize the actions of the angiotensin-converting enzyme inhibitor, enalapril, before and after development of experimentally induced heart failure. Heart failure was artificially induced, using a surgically implanted programmable ventricular pacemaker, which stimulated the heart at a rate of 245 beats/min until a low-output cardiomyopathic a state developed. This condition was then stabilized by decreasing the pacing rate to 190 beats/min. Pacing-induced heart failure was successfully induced in a mean +/- SD 4.2 +/- 1.95 weeks. The condition closely resembled the clinical, radiographic, and echocardiographic features of naturally acquired idiopathic dilated cardiomyopathy in dogs. Enalapril was well tolerated by dogs, and clinical adverse reactions did not develop. Results of echocardiographic studies indicated that enalapril treatment during the control period resulted in a significant (P < 0.05) increase in velocity of circumferential fiber shortening and a significant (P < 0.05) decrease in left ventricular ejection time. Therapeutic responses to enalapril were evident after development of heart failure. These included reduced severity of clinical signs of disease, evidence of decreased radiographically determined cardiac size (2 of 5 dogs), radiographic evidence of a reduction in pulmonary edema and congestion (4 of 5 dogs), significant (P < 0.05) reductions in left atrial and ventricular chamber dimensions (left atrial dimension, diastolic left ventricular internal dimension as determined echocardiographically), and improvement in some echocardiographic indices of left ventricular performance (velocity of circumferential fiber shortening and left ventricular ejection time).

Microcystin and related toxic peptides produced by cyanobacteria (blue-green algae) are potent and selective inhibitors of protein phosphatases 1 and 2A. We adapted existing enzymatic techniques to analyze the liver of rainbow trout after oral administration of hepatotoxic cyanobacteria. Liver tissue was removed 3 and 12 hours after treatment, and phosphatase activity was determined in liver extracts, using a specific phosphoprotein substrate. In all samples from fish exposed to toxic cyanobacteria, phosphatase activity was suppressed, whereas the control enzyme, lactate dehydrogenase, present in the same liver extract, was not affected by cyanobacteria. Thus, experimental poisoning by hepatotoxic cyanobacteria resulted in an abnormally low ratio of phosphatase to lactate dehydrogenase activity in the liver extracts. These results indicate that specific inhibition of phosphatases 1 and 2A may provide a useful diagnostic tool to determine the early effects of cyanobacteria toxic peptides directly in liver samples from poisoned animals. Although this test was developed with rainbow trout, it should be possible to extend the analysis of liver phosphatase activity to other species, including sheep and cattle, which are frequently affected by hepatotoxic cyanobacteria.

A specific thromboxane synthetase inhibitor, 3-methyl-2 (3-pyridyl)-1-indoleoctanoic acid (CGS 12970) was administered orally to 6 healthy adult Beagles at a dosage of 30 mg/kg of body weight. Blood generation of thromboxane B2 and urinary excretion of thromboxane B2 were measured before and after administration of CGS 12970. Although 97 +/- 0.4% inhibition of thromboxane B2 generation was observed within 2 hours after a single dose of CGS 12970 was administered orally, an effect on urinary excretion of thromboxane B2 was not observed. Additionally, oral administration of 30 mg/kg every 12 hours resulted in 80 +/- 14% inhibition of thromboxane B2 generation but had no effect on urinary thromboxane B2 excretion.