bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of cyclooxygenase inhibitors on furosemide- induced hemodynamic effects during exercise in horses
Authors: Olsen S. C. , Coyne C. P. , Lowe B. S. , Pelletier N. , Raub E. M. , Erickson H. H.
Published: January 2024

Furosemide, which commonly is used as a prophylactic treatment for exercise-induced pulmonary hemorrhage in horses, may mediate hemodynamic changes during exercise by altering prostaglandin metabolism. To determine if furosemide's hemodynamic effects during exercise in horses could be reversed, cyclooxygenase inhibitors were administered with furosemide. Four treatments were administered 4 hours prior to treadmill exercise at 9 and 13 m/s. They included a control treatment (10 ml of 0.9% NaCl solution, iv), furosemide (1 mg/kg of body weight, iv) administered alone, and furosemide in combination with phenylbutazone (4 mg/kg, iv, q 12 h for 2 days) or with flunixin meglumine (1.1 mg/kg, iv, on the day of experiment). Five horses were randomly assigned to complete all treatments. Physiologic variables at rest prior to exercise were not influenced by treatments. Furosemide, administered alone, reduced mean right atrial pressure and mean pulmonary artery pressure during exercise. The combinations of furosemide and flunixin meglumine or furosemide and phenylbutazone, at both levels of exercise intensity, returned mean right atrial pressure and mean pulmonary artery pressure to the value of the control treatment. During rest and exercise, plasma lactate concentration, pcv, heart rate, mean carotid artery pressure, oxygen consumption, carbon dioxide elimination, and cardiac output were not altered by any of the treatments. At 5 minutes after exercise, the administration of furosemide, alone or with phenylbutazone, reduced mean right atrial pressure. Other measured variables were not significantly influenced by treatments during recovery from exercise. These results suggested that cyclooxygenase inhibition partially reverses the decrease in mean right atrial pressure or pulmonary artery pressure induced by furosemide during exercise. Furosemide may mediate some of its physiologic activities in exercising horses through the cyclooxygenase pathway.
Effects of low-dose aspirin and specific thromboxane synthetase inhibition on whole blood platelet aggregation and adenosine triphosphate secretion in healthy dogs
Authors: Grauer Gregory F. , Rose Barbara J. , Toolan LeeAnn , Thrall Mary Anna Hull , Colgan Sean P.
Published: January 2024

Platelet aggregation and adenosine triphosphate (atp) secretion in response to arachidonic acid (10 μM) or collagen (5 μg/ml) were compared in healthy, adult female Beagles treated with low-dosage aspirin (3.5 mg/kg of body weight, po, q 12 h for 7 treatments) or with CGS 12970, a specific thromboxane synthetase inhibitor (10 mg/kg, po, q 8 h for 10 treatments). Platelet aggregation was assessed in whole blood by use of an electrical impedance method. Baseline values obtained prior to treatment served as controls. Addition of arachidonic acid to blood from nontreated dogs resulted in significantly (P < 0.001) increased impedance, but had no effect in blood from dogs treated with either aspirin or CGS 12970. Treatment with CGS 12970 or aspirin significantly (P < 0.001) decreased platelet atp secretion in response to arachidonic acid, compared with baseline values; however atp secretion in aspirin-treated dogs was significantly (P < 0.01) less than atp secretion in CGS 12970-treated dogs. Differences in platelet aggregation were not observed between control dogs and aspirin- or CGS 12970-treated dogs in response to collagen as an aggregant, however, collagen-induced platelet atp secretion was significantly (P < 0.001) decreased in dogs treated with aspirin, compared with control values and values from dogs treated with CGS 12970. In dogs treated orally with 0.1, 0.2, 1.0, or 10 mg of CGS 12970/kg, dose-dependent inhibition of arachidonic acid-induced platelet aggregation was observed, with impedance changes not observed at the 10-mg/kg dosage and normal platelet aggregation associated with the 0.1-mg/kg dosage. After a single orally administered dosage of 10 mg of CGS 12970/kg, platelet aggregation was maximally inhibited at 1 hour, remained negligible through 12 hours, and returned to normal by 96 hours. Platelet numbers were not affected by treatment with CGS 12970. These results indicate that similar to low-dose aspirin administration, treatment with CGS 12970 decreases arachidonic acid-induced, but not collagen-induced, whole blood platelet aggregation in dogs. Low-dose aspirin administration, however, was more effective than CGS 12970 treatment in reducing arachidonic acid- and collagen-induced platelet atp secretion.
Effect of head and neck position on respiratory mechanics in horses sedated with xylazine
Authors: Lavoie J. P. , Pascoe J. R. , Kurpershoek C. J.
Published: January 2024

We studied the temporal changes in respiratory mechanics associated with xylazine administration (1.1 mg/kg of body weight, iv) in standing horses (experiment 1), and determined the effects of head and neck position (experiment 2) and atropine administration (experiment 3) on the observed changes.

Thoroughbred geldings, 3 to 5 years old (5 in experiment 1, 4 in experiments 2 and 3) were used. Flow rates were obtained from a pneumotachograph and a differential transducer attached to a tight-fitting mask. Electronic integration of the flow signal gave tidal volume. Total pulmonary pressure (PL) was defined as the difference between esophageal pressure, measured with a balloon sealed to the end of a polyethylene catheter, and mask pressure. In experiment 3, a blunt cannula positioned in the dorsal third of the eighth or tenth intercostal space was used to estimate transpulmonary pressure. Lateral tracheal pressure was measured, using a polypropylene catheter inserted percutaneously in the mid-extrathoracic tracheal lumen. Upper and lower airway pressures were defined as the difference between mask pressure or transpulmonary pressure and lateral tracheal pressure, respectively.

Five observations were made: (1) There was a significant (P < 0.05) increase in PL from 10 to 40 minutes after administration of xylazine. (2) Although an overall agreement between head and neck position and PL was detected, the maximal PL value was not always obtained with lowest head and neck position. (3) Lower and upper airway resistance increased with low head carriage, with a greater increase in upper airway resistance resulting in a decrease in lower to total airway resistance ratio. (4) Increased airway resistance was reversed by elevating the head and neck. (5) Atropine did not prevent the increase in airway resistance during sedation with xylazine and had no effect on resistance with changes in head position.
Effect of repeated doses of albendazole on enantiomerism of its sulfoxide metabolite in goats
Authors: Benoit Etienne , Besse Stçphane , Delatour Paul
Published: January 2024

Five adult Saanen goats were dosed orally 3 times with albendazole (2.5 mg/kg of body weight) at 24-hour intervals, and blood samples were taken by jugular venapuncture at standardized intervals. Plasma was analyzed to determine concentrations of S-oxidation metabolites, and a chiral column was used for enantiomeric discrimination of the sulfoxide metabolite of albendazole. Marked changes were evident between the first and subsequent plasma profiles concerning, on one hand, the proportions of sulfoxide and sulfone metabolites concentrations and, on the other hand, the enantiomeric balance of the sulfoxide metabolite. These correlated phenomena may be explained by the following arguments: the enzyme responsible for sulfoxidation is mainly a flavine-containing monooxygenase, whereas the enzyme responsible for sulfonation is a cytochrome-dependent monooxygenase; the latter, but not the former, is induced by albendazole; the enantioselectivities of both enzymic systems are opposite, the flavine produces the (+) sulfoxide, whereas the cytochromes can use as a substrate, specifically, the (-) sulfoxide.
Cytogenetic characterization of the Madin-Darby bovine kidney cell line
Authors: Kopp Ewald , Nowotny Norbert , Mayr Burkhard , Schleger Walter
Published: January 2024

The permanent bovine cell line, Madin-Darby bovine kidney, was cytogenetically analyzed. Chromosomal staining indicated 52 metaphase chromosomes with variations from 49 to 54. The isochromosomes 5, 12, and 13, and centric fusions between chromosomes 1 and 26, 9 and 11, 9 and 24, 17 and 25, 18 and 23, 20 and 24, and 24 and 27 were considered marker chromosomes.
Inhibition of interleukin 1-mediated proteoglycan degradation in bovine articular cartilage explants by addition of sodium hyaluronate
Authors: Morris Elisabeth A. , Wilcon Sandra , Treadwell Benjamin V.
Published: January 2024

The effect of exogenous hyaluronate on normal cartilage metabolism and interleukin-1 (il-1)-induced cartilage matrix degradation was investigated in a bovine cartilage explant culture system. Addition of hyaluronate at a concentration of 1.5 mg/ml to cartilage culture explants consistently decreased normal proteoglycan release from the matrix to a value less than that found in control cultures. Addition of 1.5 mg of hyaluronate/ml to il-1 stimulated cartilage culture systems reduced proteoglycan release from the matrix by 83 to 113%. The reduction in control and il-1-stimulated proteoglycan degradation by hyaluronate had a concentration-dependent trend.

Evaluation of alterations in protein (enzyme) release by il-1-stimulated chondrocytes after introduction of hyaluronate was evaluated by use of sodium dodecyl sulfate agar gel electrophoresis of cartilage-conditioned media. The quantity or the molecular weight profile of il-1-induced proteins did not differ after introduction of hyaluronate into the culture system.

Results indicate that introduction of high molecular weight hyaluronate into cartilage culture systems results in a decrease in proteoglycan release from the matrix in control systems, as well as in cultures incubated with il-1. Because il-1-stimulated protein synthesis by chondrocytes remains unchanged after addition of exogenous hyaluronate, the mechanism of inhibition of matrix degradation does not appear to be interference with binding of il-1 to chondrocytes or to be inhibition of the production of neutral metalloproteases, including stromelysin.
Evaluation of intestinal villus height in rats after ischemia and reperfusion by administration of superoxide dismutase, polyethylene glycol-conjugated superoxide dismutase, and two 21-aminosteroids
Authors: Stone William C. , Bjorling Dale E. , Southard James H. , Galbreath Elizabeth J. , Lindsay William A.
Published: January 2024

Intestinal ischemia was induced and maintained for 60 minutes in male Sprague-Dawley rats weighing 175 to 225 g. Prior to reperfusion, the following drugs were administered via the caudal vena cava: 0.9% NaCl (0.5 ml), superoxide dismutase (sod; 1,000 IU/kg of body weight), polyethylene glycol-conjugated sod (peg-sod; 1,000 IU/kg), or the 21-aminosteroids, U74006F (3 mg/kg) or U78715G (3 mg/kg). A sham-operated control group was included. Animals from each group were euthanatized at 5 periods of reperfusion: 5 minutes, 30 minutes, 18 hours, 3 days, and 7 days after reperfusion. Fixed tissues were embedded in paraffin, sectioned at 5 μm, and stained with H&E. Villi profiled in cross section were measured from the crypt villus junction to the tip of the villus. The mean villus height for each rat was calculated and compared by two-way anova to determine the effects of time and treatment.

Villus height was maintained after 30 minutes of reperfusion in rats of the sham- and U74006F-treated groups; U78715G and sod treatment attentuated the loss in villus height, and villus height was not maintained in the peg-sod- and 0.9% NaCl-treated rats. In all rats, villus height was comparable to, or was greater than villus height in sham-operated controls by 18 hours after reperfusion in all animals and remained constant through 7 days.

Administration of the 21-aminosteroids maintained villus height after ischemia and reperfusion. Treatment with peg-sod did not maintain villus height to the degree observed in rats treated with sod.
Effect of age on activation of porcine intestinal guanylate cyclase and binding of Escherichia coli heat-stable enterotoxin (STa) to porcine intestinal cells and brush border membranes
Authors: Jaso-Friedmann Liliana , Dreyfus Lawrence A. , Whipp Shannon C. , Robertson Donald C.
Published: January 2024

Development of age-dependent resistance to enterotoxigenic Escherichia coli was studied, using isolated enterocytes and brush border membranes (bbm) from 7-day-old and 7-week-old pigs. Binding of 125I-labeled heat-stable (125I-STa) enterotoxin to enterocytes and bbm was specific, temperature- and time-dependent, saturable, and partially reversible. Scatchard analysis revealed a single class of receptors. Mean ± sd avidity of binding (apparent affinity constant, Ka) of 125I-STa to enterocytes from 7-day-old and 7-week-old pigs was 2.14 ± 0.29 × 108 and 2.72 ± 0.25 × 108 L/mol, respectively. Numbers of STa receptors were calcuated to be 64,903 ± 2,900/enterocyte for 7-day-old pigs and 53,029 ± 3,117/enterocyte for 7-week-old pigs. Numbers of STa receptors expressed per milligram of bbm protein from 7-day-old pigs were 2.66 × 1011, compared with 2.29 × 1011 for bbm from 7-week-old pigs. By 5 minutes after addition of STa to reaction mixtures, intracellular cyclic guanosine monophosphate concentration increased 13.9-fold in enterocytes from 7-day-old pigs and 8.7-fold in enterocytes from 7-week-old pigs. The particulate guanylate cyclase activity associated with bbm from 7-week-old pigs was slightly more sensitive to low amounts of STa, compared with bbm from 7-day-old pigs; however, differences were not observed at intermediate and high amounts. These data indicate that lack of a secretory response to STa by older pigs is not attributable either to decreased numbers of STa receptors or to decreased signal response between the STa receptor and membrane-bound guanylate cyclase. Development of age-dependent resistance by porcine small intestine to STa appears to be attributable to steps in the secretory pathway that respond to increased concentration of cyclic guanosine monophosphate.
Effect of treatment with oxytetracycline during the acute stages of experimentally induced equine ehrlichial colitis in ponies
Authors: Palmer J. E. , Benson C. E. , Whitlock R. H.
Published: January 2024

Eighteen ponies were inoculated iv with Ehrlichia risticii-infected P388D1 mouse monocyte cells. Twenty-four hours after onset of fever (rectal temperature > 38.8 C), 9 ponies were treated with oxytetracycline (6.6 mg/kg of body weight, iv, q 24 h) for 5 days. The remaining 9 ponies served as infected nontreated controls. Mean scores of the following variables were not significantly different between groups on the day treatment was begun: rectal temperature, diarrhea, borborygmal sounds, feed intake, mental attitude, and evidence of a hyperresonant area in the abdomen. All ponies were observed for progression of clinical signs typical of ehrlichial colitis. Within 12 hours of initiation of treatment, only 1 treated pony had a rectal temperature > 38.8 C and most rectal temperatures were < 38.3 C. In contrast, only 2 control ponies had rectal temperatures < 38.8 C (mean rectal temperature values were significantly, P = 0.01, different between groups). In the treatment group, 4 ponies had no signs of depression after the first day of treatment, and only 1 had signs of depression after the second day of treatment (mean scores between groups were significantly different, P = 0.01). Feed intake remained normal in 4 treated ponies and improved in 4 of the remaining 5 after treatment began. Most of the control ponies had a progressive decrease in their feed intake during the observation period (mean scores between groups were significantly, P = 0.01, different). Three ponies in the control group and 2 ponies in the treatment group developed diarrhea before the treatment observation period began. Of the remaining 6 control ponies, 4 developed diarrhea after the treatment observation period began. None of the ponies in the treatment group developed diarrhea after treatment began. A profound decrease in borborygmal sounds, with silent periods lasting longer than 3 minutes, developed in 7 control ponies. Only 2 treatment ponies had borborygmi decreased to this level (mean scores between groups were significantly, P = 0.01, different). Three of 9 control group ponies developed severe disease and were euthanatized. All treatment-group ponies survived. In surviving ponies, clinical signs lasted 8 to 16 days (mean, 11.5) in the control group, but lasted only 1 to 7 days (mean, 4.5) in the treatment group (P = 0.01). Ponies from the treatment group did not develop clinical signs when reinoculated with Ehrlichia risticii at 4 and 8 months after original inoculation.
Effect of xylazine on the arrhythmogenic dose of epinephrine in thiamylal/halothane-anesthetized horses
Authors: Gaynor James S. , Bednarski Richard M. , Muir William W.
Published: January 2024

The effect of xylazine on the arrhythmogenic dose of epinephrine (ade) was studied in 9 horses. Anesthesia was induced by administration of guaifenesin (50 mg/kg of body weight, iv) followed by thiamylal (4 to 6 mg/kg, iv) and was maintained at 1 minimal alveolar concentration (mac) of halothane (0.89%). Base apex ecg and facial artery pressure were recorded. Epinephrine was infused in a sequence of arithmetically spaced increasing rates (initial rate 0.25 µg/kg/min) for a maximum of 10 minutes. The ade was defined as the lowest epinephrine infusion rate to the nearest 0.25 µg/kg/min at which at least 4 premature ventricular depolarizations occurred in a 15- second period. Xylazine (1.1 mg/kg, iv) was administered after the control ade was determined. Xylazine did not significantly alter the ade (control, 1.12 ± 0.38 µg/kg/ min; xylazine, 1.21 ± 0.46 µg/kg/min). Blood pressure increased transiently for 8 minutes after xylazine administration. Baseline systolic and diastolic arterial pressures and heart rate were not significantly different from control baseline pressures and heart rate 15 minutes after xylazine administration. Blood pressure and heart rate increased significantly during control and xylazine ade determinations. Significant differences in pH, Pao2, Paco2, or base excess were not observed between baseline and ade in the control or xylazine groups. One horse developed atrial fibrillation, and 2 horses developed ventricular fibrillation during ade determinations.
Changes in erythrocyte deformability in NaCl-induced right-sided cardiac failure in broiler chickens
Authors: Mirsalimi S. M. , O’Brien P. J. , Julian R.J.
Published: January 2024

In this study, we tested the hypothesis that erythrocyte deformability is decreased in the development of cardiac failure induced by NaCl toxicosis. Deformability of erythrocytes and routine hematologic and biochemical variables were measured in 6 of 50 chickens that were given 5 g of NaCl/L in their drinking water from day 7 to day 42, and were compared with values in 6 of 50 healthy chickens given free access to tap water. Deformability was assessed by passing a 10% suspension of erythrocytes through a polycarbonate membrane with 5-µm pores. Chickens were euthanatized and heart and body weights were determined.

Treatment with NaCl induced right-sided cardiac failure up to day 28. The ratios of heart weight to body weight were greater, for right ventricle by 20 to 64% and for left ventricle by 15 to 27%, attributable to NaCl treatment. Deformability of erythrocytes of NaCl-treated chickens was markedly decreased, in association with increased erythrocyte size and plasma Na+ concentration. However, only part of the decreased deformability could be explained by swelling of erythrocytes. Decreased deformability could not be explained by increased cell viscosity because mean corpuscular hemoglobin concentration, the primary determinant of erythrocyte viscosity, was decreased. Because decreased deformability of erythrocytes has been demonstrated previously to be associated with increased vascular resistance, decreased deformability may have contributed to the development of right-sided cardiac failure in these chickens.
Effect of sodium hyaluronate in collagenase-induced superficial digital flexor tendinitis in horses
Authors: Foland J. W. , Trotter G. W. , Powers B. E. , Wrigley R. H. , Smith F. W.
Published: January 2024

Superficial digital flexor tendinitis was induced in each forelimb of 8 horses by injecting 4,000 U of collagenase into the midmetacarpal region of the tendon. In each horse, each tendon was treated 24 and 96 hours after the collagenase injection with sc injections of sodium hyaluronate (treated limbs) or an equal volume of 0.9% NaCl solution (control limbs). Exercise was restricted for the first 3 weeks of the study, and a controlled exercise program was instituted for the remainder of the study. Horses were evaluated clinically for lameness, tendon swelling, and midmetacarpal limb circumference. Ultrasonographic examinations were performed regularly (11 examinations/horse) throughout the study, and all horses were euthanatized 12 weeks after collagenase injections. Tendons from 4 horses were harvested for biomechanical testing, and samples were obtained from tendons from the remaining 4 horses for biochemical analysis of collagen. Samples were obtained from all tendons for microscopic evaluation. Significant differences between treated and control tendons were not noticed in any of the variables examined in live horses, although trends toward less lameness in treated limbs and toward better healing on ultrasonographic examination in control limbs were recorded. Significant differences were not noticed in biomechanical or biochemical evaluations, and the only significant (P < 0.05) microscopic finding was more severe inflammation in tendons from treated limbs. This study did not reveal significant benefits of treatment with sodium hyaluronate outside a synovial sheath on tendon repair in collagenase-induced tendinitis.
Risk factors associated with the incidence of seroconversion to caprine arthritis-encephalitis virus in goats on California dairies
Authors: Rowe J. D. , East N. E. , Franti C. E. , Thurmond M. C. , Pedersen N. C. , Theilen G. H.
Published: January 2024

Incidence of seroconversion to caprine arthritis-encephalitis virus (caev) was determined for 1,194 goats on 11 dairies, using 2 repeated annual herd tests for caev. Current life table methods were used to compare age-specific incidence of seroconversion for pasteurized milk-raised and unpasteurized milk-raised goats. Logistic regression models were used to determine the risk factors associated with caev seroconversion, and to estimate odds ratios for seroconversion for various factor levels. Goats raised by unpasteurized milk-feeding methods were 2.5 to 6.7 times more likely to seroconvert than were goats raised by pasteurized milkfeeding methods, depending on the method of comparison. Similarly, 61.6 to 85.0% of seroconversions in yearling goats possibly were attributable to unpasteurized milk feeding. Among yearling goats, caev seroconversion was associated with feeding method, breed, and source of goat (herd of origin) when the effect of dairy was considered. In addition to the 6.7 times greater risk of seroconversion for unpasteurized milk-raised goats, yearling goats of the Saanen and Toggenburg breeds were 2.2 and 3.3 times, respectively, more likely to seroconvert than were Alpine yearling goats. Yearling goats purchased from another source were less likely to seroconvert than were yearlings raised on the dairy where they were studied. Among goats > 1 year old, age was associated with risk of seroconversion. Goats that were 3 years old or were ≥ 4 years old were 1.7 and 3.2 times, respectively, more likely to seroconvert than were 2-year-old goats, when adjusted for effect of dairy. The effects of dairy were significant (P ≤ 0.001) in yearling and older goats.
Cytologic findings of tracheobronchial aspirates from 66 Thoroughbred racehorses
Authors: Sweeney Corinne Raphel , Humber Kent A. , Roby Kate A. W.
Published: January 2024

Tracheobronchial aspirates obtained from 66 healthy Thoroughbred racehorses in training at the same track were examined. Twenty-seven percent of the horses had > 20% neutrophils in the aspirate. Eosinophils, mast cells, giant cells, and Curschmann's spirals of mucus were observed in 94, 83, 65, and 42% of the horses, respectively. Hemosiderophages were observed in 86% of the horses, half of which had previous confirmation of exercise-induced pulmonary hemorrhage. Although fungal elements were seen in 70% of the horses, bacteria were detected in only 3% of the horses. The authors conclude that inflammatory airway disease is widespread in the racing Thoroughbred population.
Evaluation of intra-articularly administered sodium monoiodoacetate-induced chemical injury to articular cartilage of horses
Authors: Gustafson Scott B. , Trotter Gayle W. , Norrdin Robert W. , Wrigley Robert H. , Lamar C.
Published: January 2024

Three doses of sodium monoiodoacetate (mia) were used to induce degenerative changes in articular cartilage in middle carpal joints of horses. Twelve young (2- to 5-year-old) horses, free of lameness, were randomly allotted to 3 groups. One middle carpal joint of each horse was injected with 0.9% NaCl solution (control joint). The contralateral middle carpal joint was injected with 0.09 mg of MlA/kg of body weight (group 1); 0.12 mg/kg (group 2); or 0.16 mg/kg (group 3). After mia administration, horses were allowed ad libitum exercise in a 2-acre paddock for 12 weeks. At the end of the study, gross and microscopic tissue changes were evaluated and biochemical analyses of articular cartilage were done. Grossly, diffuse partial thickness articular cartilage lesions were observed in group-2 (n = 2) and group-3 (n = 4) horses, but not in group-1 horses. Articular cartilage uronic acid content was significantly (P < 0.03) decreased in all mia-injected joints, compared with controls. Articular cartilage matrix staining with safranin-O was decreased in 3 of 4 mia- injected joints of group-1 horses and in all mia-injected joints of group-2 and group-3 horses, compared with controls (P < 0.06). Microscopic degenerative changes in articular cartilage were not significantly different between mia-injected and control joints in group-1 horses, but were increased (P<0.06) in all MlA-injected joints of group-2 and group-3 horses, compared with controls. Qualitatively, decreased matrix staining and degenerative changes were more severe in group-3 horses. On the basis of articular cartilage gross and microscopic changes, as well as biochemical changes, 0.12 mg of mia/kg injected intra-articularly was determined to induce moderate degrees of articular cartilage degeneration. This model of chemically induced articular cartilage injury could be useful for evaluating treatment effects of anti-arthritic drugs in horses.
Antigenic variation among transmissible gastroenteritis virus (tgev) and porcine respiratory coronavirus strains detected with monoclonal antibodies to the S protein of tgev
Authors: Simkins Ronald. A. , Weilnau Peggy A. , Bias Jerome , Saif Linda J.
Published: January 2024

Five nonneutralizing monoclonal antibodies (MAb) generated to the virulent Miller strain of transmissible gastroenteritis virus (tgev) and specific for the S protein were characterized. Competition assays between purified and biotinylated MAb indicated that MAb 75B10 and 8G11 mapped near a new subsite, designated V and 2 MAb, 44C11 and 45A8, mapped to a previously designated subsite D. A fifth MAb mapped between subsites V and E. These MAb were tested with 3 previously characterized MAb to subsites A, E, and F in fixed-cell ELISA and cell culture immunofluorescent assays against 5 reference and 9 field strains of TGEV and 2 US strains (ISU-1 and ISU- 3) of porcine respiratory coronavirus (prcv). Subsites A, E, and F were conserved on all tgev and prcv strains examined. The 2 MAb to subsite V, 8G11 and 75B10, reacted only with the Miller tgev strains (M5C, M6, and M60), except that 75B10 also recognized field strain U328. The MAb 11H8 did not react with 4 field strains or the Purdue strains of tgev. The 2 MAb to subsite D reacted with all tgev strains examined, but not with 2 US prcv strains, 2 European PRCV strains, 1 feline infectious peritonitis virus strain, and 1 canine coronavirus strain. Because of this specificity for TGEV, but not PRCV, these latter 2 subsite D MAb may be useful for the development of competition ELISA to differentiate serologically between tgev and prcv infections in swine, similar to the currently used European subsite D MAb.
Antagonism of a specific dopaminergic receptor agonist with metoclopramide in horses
Authors: Eades Susan C. , Moore James N.
Published: January 2024

Changes in lateral cecal arterial blood flow, mean internal carotid arterial pressure, and heart rate caused by nasogastric administration of fenoldopam (3, 6, and 9 mg/kg of body weight), a selective agonist of dopaminergic receptors, were recorded in 7 healthy horses. Cecal arterial blood flow was significantly increased within 30 minutes after administration of fenoldopam at all 3 dosages, with the peak increases from baseline (67.8 ± 17.5 ml/min) being 125 ± 28, 120 ± 22, and 153 ± 32 ml/min for 3, 6, and 9 mg/kg, respectively. Although carotid arterial pressure did not change significantly after administration of fenoldopam at the dosage of 3 mg/kg, administration of fenoldopam at the dosages of 6 and 9 mg/kg significantly reduced carotid arterial pressure from 113 ± 10 to 88 ± 3 and 81 ± 5 mm of Hg, respectively. Intravenous infusion of metoclopramide, a dopaminergic receptor antagonist, at the rate of 0.125 mg/kg/h, blocked the effect of fenoldopam on cecal arterial blood flow and carotid arterial pressure. It was concluded that dopaminergic receptors mediate alterations in local blood flow and systemic pressure in horses.
Electromyography of the pelvic diaphragm and anal sphincter in dogs with perineal hernia
Authors: Sjollema Bart E. , Venker-van Haagen Anjop J. , van Sluijs Frederik J. , Hartman Frits , Goedegebuure Sinus A.
Published: January 2024

The innervation of the levator ani and coccygeal muscles and the external anal sphincter was studied by anatomic dissection in 6 clinically normal male dogs and by electrical stimulation in 5 clinically normal male dogs. Variations in innervation occasionally were found that were comparable to those reported in previous studies.

Electromyographic recordings were made from the levator ani and coccygeal muscles and from the anal sphincter in 40 dogs during perineal hernia repair. Spontaneous potentials of 4 types were found in 35 dogs: fibrillation potentials, positive sharp waves, complex repetitive discharges, and fasciculations.

Biopsy specimens of the cranial part of the levator ani muscle were taken in 12 dogs during perineal hernia repair. Histologic examination revealed atrophy in 7 specimens. Spontaneous potentials were recorded from all muscles with histologic evidence of atrophy. All examinations of the levator ani muscle concerned the cranial part of this muscle, because the caudal part was absent in all 40 dogs.

From combined results of electromyography and histologic examination, it was concluded that atrophy of the muscles of the pelvic diaphragm, which develops in some dogs with perineal hernia, is likely to be of neurogenic origin. Nerve damage is localized in the sacral plexus proximal to the muscular branches of the pudendal nerve or in the muscular branches separately.
Early detection of bovine leukemia virus in cattle by use of the polymerase chain reaction
Authors: Kelly E. Jane , Jackson M. Keven , Marsolais Gregoire , Morrey John D. , Callan Robert J.
Published: January 2024

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-base-pair 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.
Use of polymerase chain reaction to diagnose bovine leukemia virus infection in calves at birth
Authors: Agresti Alessandra , Ponti Wilma , Rocchi Mara , Meneveri Raffaella , Marozzi Anna , Cavalleri Daniela , Peri Enzo , Poli Giorgio , Ginelli Enrico
Published: January 2024

A specific polymerase chain reaction (pcr) assay was devised, allowing detection of 1 bovine leukemia virus (blv)-infected cell in 104 bovine lymphocytes. The efficacy of field application of the developed method was verified by evaluating the rate of viral transmission to calves from infected cows, whether they have persistent lymphocytosis. With this objective, 43 calves were simultaneously tested at birth and at 6 months of age for viral antibodies in serum and for proviral dna in lymphocytes. At birth, 36 calves were blv-negative and 3 were blv-positive by results of serologic and dna-based assays. Conversely, results for 4 calves had lack of correlation between the diagnostic methods. In particular, 2 calves were dna-positive and antibody-negative for blv and 2 other calves had the opposite test results. At 6 months of age, when the immunologic pattern more closely reflects the status of calves’ immune response, independent of maternal antibodies, all calves dna-negative for blv at birth (n = 38), were consistently pcr- and antibody-negative for blv. On the contrary, the cattle dna-positive for blv at birth (n = 5), whether seropositive or not, were pcr- and antibody-positive for blv, at the time of the second screening. Thus, these results indicate reliability of the pcr to diagnose perinatal blv infection. Furthermore, the observation that all calves found to be infected at birth were born to blv-positive cows with persistent lymphocytosis, indicates that the persistent lymphocytosis status of the cow may represent a factor associated with blv infection in utero.
Evaluation of skin viability in dogs, using transcutaneous carbon dioxide and sensor current monitoring
Authors: Rochat Mark C. , Payne John T. , Pope Eric R. , Wagner-Mann Colette C. , Pace Lanny W.
Published: January 2024

Transcutaneous oxygen monitoring is commonly used in human beings to assess skin viability. Little attention has been directed toward the use of transcutenaous carbon dioxide (PCO2-TC) monitoring for the same purpose. The application of PCO2-TC monitoring for evaluating skin viability in dogs was investigated.

The changes in PCO2-TC and local power reference (LPR) values were measured from 16 skin flaps created along the lateral hemithoraces of 4 dogs. Transcutaneous PPCO2 and LPR values were serially recorded from the base and apex of each flap for 12 hours. A single measurement was obtained from each flap base and apex 24 hours after surgery. Arterial blood gas analyses were obtained to compare central PCO2 values with peripheral skin PCO2 values. The flaps were observed for 4 days and then harvested for histologic examination. Full-thickness skin biopsy specimens were obtained 24 hours after surgery and when the flaps were harvested to evaluate the viability of the apex and base of the flaps. A subjective grade was assigned to all skin biopsy specimens during histologic examination.

For all measurements, a significant difference was found between the PCO2-TC values for apices and bases of the flaps. The mean PCO2-TC for all bases was 52.66 mm of Hg ± 2.24 (SEM), and the mean PCO2-TC for all apices was 106.4 mm of Hg ± 2.44. The regional carbon dioxide index (apex PCO2-TC/base PCO2-TC) was 2.02.

A significant difference was not found between the LPR values for bases and apices. The mean lpr for all bases was 253.23 mW ± 4.06, and the mean LPR for all apices was 243.53 mW ± 4.49.

A signficant difference was found between the histologic grades assigned to the collective bases and apices 4 days after creation of the flaps. A difference was not found between the collective bases and apices 24 hours after flap creation. On the basis of our findings, transcutaneous carbon dioxide monitoring is a useful method of evaluating skin viability in dogs.
Skeletal muscle of cattle affected with progressive degenerative myeloencephalopathy
Authors: Troyer Deryl , Cash Walter , Leipold Horst
Published: January 2024

Skeletal muscle from multiple sites of 6 cattle afflicted with progressive degenerative myeloencephalopathy was analyzed by transmission electron microscopy and compared with skeletal muscle taken from 2 clinically normal cattle (controls) similarly studied. Major changes in the affected muscle included abnormal myoneural junctions with redundant junctional folds that were abnormally long and branching, and occasionally separated from the synaptic site; multiple vacuoles of variable size clustered in subsarcolemmal positions and in rows between myofibrils; bizarre mitochondria with thin connecting stalks, large electron-dense bodies, and abnormal cristae; and cone-shaped projections of the sarcolemma. These findings indicate that myopathy is part of the progressive degenerative myeloencephalopathy phenotype.
Enzyme-linked immunosorbent assay and flow cytometric methods to screen hybridoma culture supernatants for antibodies to bovine neutrophil surface antigens, and monoclonal antibody production and characterization
Authors: Salgar Shashikumar K. , Paape Max J. , Alston-Mills Brenda
Published: January 2024

Enzyme-linked immunosorbent assay and flow cytometric methods to screen hybridoma culture supernatants for antibodies to bovine neutrophils (surrace antigen-specific) were optimized. Sensitivity of the 2 methods was compared. A panel of 14 murine monoclonal antibodies (mab) to surface antigens of bovine polymorphonuclear neutrophilic leukocytes (neutrophils) was produced by hybridoma technology, and their isotypes were determined by wholecell elisa. Monoclonal antibody reactivity with neutrophils, eosinophils, and lymphocytes isolated on phosphate-buffered saline solution and on Ficoll-sodium diatrizoate were compared. Biochemical characterization of antigens recognized by mab was performed by immunoblot analysis. Neutrophil plasma membranes were isolated on sucrose gradients (20, 32, and 50%) and purified for polypeptide characterization. Neutrophil surface proteins were characterized by external labeling with 125I.

The flow cytometric method was proven to be more sensitive and rapid than elisa to screen hybridoma supernatants. This method allowed light-scatter gating of live neutrophil populations for analysis, which eliminated nonspecific binding of antibodies to contaminating cells and dead neutrophils. The optimal conditions for flow cytometric analyses were 5 × 105 neutrophils and 1 µg of fluorescein-labeled F(ab′)2/assay as the second antibody. The optimal conditions for hybridoma screening by elisa were neutrophil concentration of 2.5 × 105/well, using a 96-well polystyrene microtitration plate as solid support, and 2,2′-azino-di[3-ethyl-benzthiazoline sulfonate (6)] with H2O2 as the chromogenic substrate. Tissue culture plates as solid support and 3,3′, 5,5′- tetramethyl benzidine, with H2O2 as the chromogenic substrate, were equally as sensitive.

Panel mab reacted differently with neutrophils, eosinophils, and lymphocytes. Isolation of these cells from blood on Ficoll-sodium diatrizoate generally did not alter mab reactivity.

Coomassie blue-stained gels of neutrophil plasma membrane proteins contained about 25 polypeptide bands, 13 of which were major bands. Autoradiography revealed about 11 surface proteins, 5 of which were heavily labeled with Monoclonal antibody S7G8 identified a 65-kd protein and mab S8G10 identified 65- and 70-kd proteins. On the basis of molecular weight, mab S7G8 and S8G10 are comparable to human CD15, CDl6, and CD64 molecules. The mab generated in this study are potential candidates to discern bovine neutrophil function and heterogeneity.
Enterotoxigenic, verotoxigenic, and necrotoxigenic Escherichia coli isolated from cattle in Spain
Authors: Blanco Miguel , Blanco Jorge , Blanco Jesús E. , Ramos Jacinto
Published: January 2024

To assess the role of enterotoxigenic (etec), verotoxigenic (vtec), and necrotoxigenic (ntec) Escherichia coli in cattle with diarrhea, 1,524 colonies of E coli isolated from 197 calves with diarrhea and from 112 healthy controls were investigated for production of heat-labile and heat-stable enterotoxins, verotoxins, and cytotoxic necrotizing factors (cnf1 and cnf2). The etec were isolated from only 2(1%) calves with diarrhea and from 5 (4%) healthy controls. In contrast, vtec and ntec that produced cnf2 were frequently identified. The vtec were isolated from 18 (9%) calves with diarrhea and from 21 (19%) healthy cattle (P < 0.05), whereas ntec that produced cnf2 were detected in 39 (20%) ill calves and in 38 (34%) controls (P < 0.01). Therefore, vtec and ntec that produced cnf2 were isolated significantly more frequently from healthy than diseased calves. Serogroups to which vtec belonged differed considerably from the O groups involved with ntec. Although, vtec belonged to 18 serogroups, only 4 (026, 0103, 0113, and 0157) accounted for 56% (25 of 45) of verotoxigenic strains. The ntec that produced cnf2 belonged to 26 serogroups; however, 64% (69 of 108) were from 6 serogroups (O1, 03, 015, 055, 088, and 0123). Our results are compatible with cattle being a reservoir of vtec that are pathogenic for human beings and with etec being an unusual cause of bovine colibacillosis in Galicia (northwestern Spain). Furthermore, results of this study indicate that vtec and ntec that produced cnf2 may be part of the normal intestinal flora of cattle.
Comparative efficacy of flunixin, ketoprofen, and ketorolac for treating endotoxemic neonatal calves
Authors: Semrad Susan D.
Published: January 2024

Saline (0.9% NaCl) solution or 1 of 3 nonsteroidal anti-inflammatory drugs (nsaid) was administered iv to 5 neonatal calves 15 minutes after the start of a 3-hour iv infusion of Escherichia coli lipopolysaccharide (lps; 2 µg/kg/h). Four additional calves were given a 3-hour iv infusion of saline solution alone. Clinical attitude, mean arterial blood pressure, pcv, wbc, and plasma lactate, glucose, and eicosanoid concentrations (thromboxane B2, 6-keto-PGF1α) were monitored for 12 hours.

Flunixin meglumine (1.1 mg/kg of body weight, iv), ketoprofen (2.2 mg/kg, iv), and ketorolac tromethamine (1.1 mg/kg, iv) each ameliorated the clinical signs of endotoxemia and lps-induced lacticemia, but failed to significantly alter the degree of leukopenia or hypoglycemia associated with infusion of lps. Although the 3 nsaid prevented eicosanoid production, they provided only partial protection against lps-induced hypotension. Each nsaid modified the response to lps, but none was clearly superior to the others in modulating the clinical signs or physiologic alterations induced by infusion of lps in neonatal calves.
Evaluation of the microcirculation of the equine jejunum and ascending colon after ischemia and reperfusion
Authors: Dabareiner Robin M. , Snyder Jack R. , Sullins Kenneth E. , White Nathaniel A. , Gardner Ian A.
Published: January 2024

Intramural vascular patterns of the jejunum and colon were evaluated during ischemic strangulation obstruction (iso, 70 minutes) and subsequent reperfusion (60 minutes) in 7 adult anesthetized horses. Microvasculature of experimental and control segments was described by comparison of results from microangiography, light microscopy, and scanning electron microscopy of vascular replicas. Experimental and control segments with isolated vascular arcades were removed either immediately after the experimental period or after 60 minutes of reperfusion. Blood was flushed from the vascular system by use of isotonic NaCl, and the segments were divided. Half of each segment was perfused with a modified radiopaque medium for microangiographic evaluation, and half was perfused with dilute methylmethacrylate to create a vascular replica to be studied by scanning electron microscopy. Microangiographic section also were evaluated for histologic changes.

Microvasculature of jejunal control segments and all colon segments was similar to described normal microvasculature of the equine jejunum and ascending colon. In jejunal iso segments, intramural perfusion was redistributed away from the mucosa. In the villi, the central arteriole was short and convoluted and the subepithelial capillaries were not filled. The submucosal vessels and crypt capillaries were congested, compared with those of controls, and the serosal vessels were not filled in the ischemic segments. Histologic grade II-III mucosal lesion was seen in jejunal iso segments. Reperfused jejunal segments had a transmural hyperemic response, and previously unfilled capillaries were observed in all intestinal layers. After reperfusion, the mucosal lesion progressed to grade III-IV and a cellular infiltrate and edema formation were observed in the serosa.

The intramural vasculature of the ischemic and reperfused colon remain unchanged. Minimal histologic damage was observed in the colon after 70 minutes of iso or after 60 minutes of reperfusion.
Cardiorespiratory effects of intravenous bolus administration and infusion of ketamine-midazolam in dogs
Authors: Jacobson John D. , Hartsfield Sandee M.
Published: January 2024

Twelve healthy dogs were used to determine the cardiorespiratory effects of iv administered ketamine (10 mg/kg of body weight) and midazolam (0.5 mg/kg). Half the dogs received a ketamine-midazolam combination (k-m) as a bolus over 30 seconds and the other half received the k-m as an infusion over 15 minutes. Induction of anesthesia by use of k-m was good in all dogs. Ketamine-midazolam combination as a bolus or infusion induced minimal cardiorespiratory effects, except for significant (P < 0.05) increases in mean heart rate and rate-pressure product. The increase in heart rate was greater in dogs of the infusion group. Mild and transient respiratory depression was observed in dogs of both groups immediately after administration of k-m, but was greater in dogs of the bolus group than in dogs of the infusion group. Duration of action of k-m for chemical restraint was short. Salivation and defecation were observed in a few dogs. Extreme muscular tone developed in 1 dog after k-m bolus administration.