bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of subject velocity on ground reaction force measurements and stance times in clinically normal horses at the walk and trot
Authors: McLaughlin Ron M. , Gaughan Earl M. , Roush James K. , Skaggs Chad L. 
Published: January 2024

Abstract

Objective
The objective of the study reported here was to evaluate the effects of changing velocity on stance time and ground reaction force (GRF) measurements in horses at the walk and trot.

Design
Force plate gait analysis was used to evaluate clinically normal horses at variable velocities. Ground reaction force measurements and stance times were recorded and compared.

Animals
12 adult horses.

Procedure
Data were obtained from 192 valid trials at the walk and 162 valid trials at the trot. Vertical, braking, and propulsive peak forces and impulses were measured. Pearson’s correlation coefficients were determined for velocity and stance time and all measured forces and impulses in the forelimbs and hind limbs. Trials were divided into distinct velocity ranges. Trials obtained at velocities within the established ranges were analyzed to evaluate changes in vertical, braking, and propulsive peak forces and impulses at differing speeds within the walk and trot gaits.

Results
At the walk and trot, a significant negative correlation was found between velocity and forelimb and hind limb stance times. Velocity and stance time were significantly correlated with many of the GRF and impulse measurements. Velocity was significantly correlated with vertical and braking forces in the hind limbs at the walk, with vertical force in the forelimbs at the trot, and with braking force in the forelimbs and hind limbs at the trot. Velocity and stance time correlated significantly with forelimb and hind limb vertical impulses. Forelimb and hind limb stance times decreased significantly as velocity increased. Hind limb braking force increased and forelimb and hind limb vertical impulses decreased significantly as walk velocity increased. Forelimb braking force increased significantly between velocity ranges at the trot.

Conclusions
Results of this study confirm that a significant negative linear correlation exists between subject velocity and stance times in clinically normal horses at the walk and trot. Significant correlations were also identified between velocity and many GRF measurements, indicating that subject velocity does influence the generation of GRF measurements in horses. Variation in subject velocity should be minimized when performing force-plate analysis in horses. (Am J Vet Res 1996;57:7-11)
Effects of topical administration of 0.5% apraclonidine on intraocular pressure, pupil size, and heart rate in clinically normal dogs
Authors: Miller Paul E. , Nelson Marie J. , Rhaesa Suzanne L. 
Published: January 2024

Abstract

Objective
To evaluate the effect of 0.5% apraclonidine on intraocular pressure (IOP), pupil size, and heart rate in clinically normal dogs.

Design
Randomized masked saline-controlled case study.

Animals
Nine clinically normal conditioned adult dogs of either sex.

Procedure
Normal diurnal variation in IOP, pupil size, and resting heart rate were determined from 7 AM to 7 PM (day 1). These measurements were repeated on day 2 after topical application of 60 μl of 0.5% apraclonidine to 1 randomly chosen eye of each dog. The contralateral eye received saline solution.

Results
Compared with the saline-treated fellow eye, mean IOP in the apraclonidine-treated eye was significantly reduced (3.0 mm of Hg, 16%) 8 hours after treatment. Because of mild day-to-day variations in IOP, however, IOP in the apraclonidine-treated eye on day 2 was not significantly different from day-1 baseline values obtained from the same eye. Significant mydriasis (2.1 mm, 29.7%), persisting for up to 8 hours, occurred in apraclonidine-treated eyes. Although apraclonidine did not significantly alter heart rate when all 9 dogs were viewed as a group, 4 dogs experienced a 9 to 19.5% reduction in heart rate 2 hours after treatment. Mild blanching of the conjunctiva occurred in apraclonidine-treated eyes.

Conclusions
Apraclonidine lowered IOP and, in contrast to cats where it causes miosis, induced mydriasis in dogs. Although heart rate generally is unchanged, it may be reduced in select individuals.

Clinical Relevance
Topically applied 0.5% apraclonidine may be a useful adjunct to other antiglaucoma treatment modalities in dogs, but is unlikely to be effective as the sole agent in most forms of canine glaucoma. (Am J Vet Res 1996;57:79-82)
Effects of topical administration of 0.5% apraclonidine on intraocular pressure, pupil size, and heart rate in clinically normal cats
Authors: Miller Paul E. , Rhaesa Suzanne L. 
Published: January 2024

Abstract

Objective
To evaluate the effect of a topical α2-agonist, 0.5% apraclonidine, on intraocular pressure (IOP), pupil size, and heart rate in clinically normal cats.

Design
Randomized masked saline-controlled case study.

Animals
Nine clinically normal conditioned adult cats of either sex.

Procedure
Normal diurnal variation in IOP, pupil size, and resting heart rate was determined from 7 AM to 7 PM (day 1). On day 2, the same measurements were made after the topical application of 30 μl of 0.5% apraclonidine to 1 randomly chosen eye of each cat. The contralateral eye received saline solution.

Results
Apraclonidine lowered IOP a mean of 4.8 mm of Hg (24.0%) when compared with IOP in the fellow saline-treated eye 6 hours after treatment. Unilateral administration of the drug also may have reduced IOP in both eyes. Pupil size was reduced a mean 46% in only the apraclonidine-treated eye, and miosis persisted for up to 24 hours. Heart rate was significantly lower (11.8%) at 3 hours, and 8 of 9 cats vomited after topical administration of the drug. Mild blanching of the conjunctiva occurred in all apraclonidine-treated eyes.

Conclusions
Apraclonidine reduced IOP, pupil size, and resting heart rate in clinically normal cats, but also induced undesirable systemic side-effects. In contrast to dogs where the drug induced mydriasis, apraclonidine caused miosis in cats.

Clinical Relevance
The current commercially available formulation of topical 0.5% apraclonidine is too toxic for clinical use in cats. Reformulation, or identification of a less toxic congener, may result in a clinically useful antiglaucoma preparation for cats. (Am J Vet Res 1996;57:83-86)
Scotopic threshold response of the electroretinogram of dogs
Authors: Yanase Jun , Ogawa Hiroyuki , Ohtsuka Hiromitsu 
Published: January 2024

Abstract

Objective
To study characteristics of the scotopic threshold response (STR) in dogs.

Design
We recorded the electroretinogram (ERG) in anesthetized Beagles under several recording conditions to examine characteristics of the STR.

Animals
Seven clinically normal Beagles.

Procedure
Beagles were paralyzed by continuous IV administration of muscle relaxant and were artificially ventilated with a gas mixture of nitrous oxide and oxygen during experiments. Corneal ERG were recorded, using full-field white stimuli, under several recording conditions.

Results
The canine STR was a simple corneal negative response elicited by dim stimuli below the b-wave threshold. Maximal amplitude of the canine STR was approximately 50 to 120 µV, much larger than those of other animal species, such as human beings, monkeys, and cats. Peak latency of the maximal STR was approximately 75 to 96 milliseconds. The spectral sensitivity of the canine STR corresponded to that of the canine rod visual pigment. The canine STR was completely eliminated by dim background light, which had no suppressive effect on the a- and b-waves. By using such dim background light, we could record the photoreceptor-derived a-wave in the ERG intensity series.

Conclusions
In Beagles, the STR strongly influences the ERG waveforms recorded under the dark-adapted condition. Special attention may be necessary in using the dark-adapted ERG to assess the retinal photoreceptor function. Canine STR is expected to be a good indicator of assessment of the proximal retinal function in dogs, and Beagles might be a good experimental animal for the study of the STR.(Am J Vet Res 1996;57:361-366)
Enzyme-linked immunosorbent assay for thrombin-antithrombin III complexes in horses
Authors: Topper Michael J. , Prasse Keith W. , Morris Michael J. , Duncan Alexander , Crowe Natalie A. 
Published: January 2024

Abstract

Objectives
To adapt and characterize a human ELISA kit to quantify thrombin-antithrombin III (TAT) complexes in horses, and to evaluate TAT as a marker for hypercoagulation in horses.

Animals
29 clinically normal horses used as controls, and 4 ill horses used to evaluate assay for known causes of hypercoagulation.

Procedure
A commercially available human sandwich-type ELISA kit with 2 antibodies against human thrombin and antithrombin III that bind selectively to their corresponding TAT antigenic sites was used. Equine TAT standards were made from purified equine thrombin and antithrombin III. Proteins diluted in a phosphate-buffered saline solution containing 0.1 % Tween and 1 U of heparin/ml were used to establish standard curves. Reference intervals for TAT concentration in citrated equine plasma, and intra- and interassay coefficients of variation were determined.

Results
Mean ± SD values were 3.95 ± 1.93 µg/L, with median of 3.18 µg/L and range of 1.95 to 9.03 µg/L. One horse with cecal perforation had TAT concentration of 174.30 µg/L, and a horse infused IV with endotoxin had TAT concentration of 62.98 µg/L 12 hours after infusion.

Conclusions
The data suggest that human TAT ELISA kits can be used to measure TAT concentration in citrated equine plasma, and that TAT is a marker for hypercoagulation in horses.

Clinical Relevance
Assays for equine TAT many help to further characterize the hypercoagulable state in horses. (Am J Vet Res 1996;57:427–431)
In vitro effect of ketones and hyperglycemia on feline hemoglobin oxidation and D- and L-lactate production
Authors: Fallin Carol W. , Christopher Mary M. 
Published: January 2024

Abstract

Objectives
To investigate in vitro effects of ketosis and hyperglycemia on feline erythrocyte Heinz body formation, reduced glutathione (GSH) concentration, and D-and L-lactate production, and to identify potential metabolic mechanisms of oxidative stress in diabetic cats.

Design
Washed feline erythrocytes suspended in buffers containing normal or high glucose concentration were incubated with various concentrations of ketone bodies and tested at defined time intervals for Heinz bodies, GSH concentration, and D- and L-lactate production.

Animals
Three healthy female domestic cats.

Procedure
Erythrocytes were washed, suspended in buffers containing 5 mM glucose (simulates euglycemia) or 25 mM glucose (simulates hyperglycemia), and incubated with acetone (5 and 10 mM), acetoacetate (5 and 10 mM), or β-hydroxybutyrate (5 and 25 mM) for 24 hours at 37 C. Aliquots were stained with new methylene blue for Heinz bodies, and assayed spectrophotometrically for GSH and D- and L-lactate concentrations. Experiments were done in triplicate. Data were analyzed, using ANOVA with repeated measures.

Results
Neither high glucose concentration nor ketosis had direct effects on Heinz body formation or GSH values. Glutathione decreased to 89% of initial values over the 24-hour period in all samples. High glucose concentration also had no effect on erythrocyte D-lactate production; however, the rate of D-lactate production was slightly increased in samples containing 25 mM β-hydroxybutyrate. Linear L-lactate production confirmed metabolic viability of the erythrocyte suspensions. Samples in high glucose concentration produced L-lactate at a slightly higher (1.2×) rate than did samples in normal glucose concentration.

Conclusions
High glucose concentration and ketosis do not account directly for oxidative damage and glyoxalase induction in feline erythrocytes in vitro, although high concentrations of β-hydroxybutyrate may stimulate D-lactate formation. (Am J Vet Res 1996;57:463–467)
Alterations in colonic smooth muscle function in cats with idiopathic megacolon
Authors: Washabau Robert J. , Stalls Ilse H. 
Published: January 2024

Abstract

Objective
To determine whether colonic smooth muscle dysfunction is involved in the pathogenesis of idiopathic megacolon in cats.

Design
In vitro smooth muscle mechanical measurements.

Animals
Colon from healthy cats and cats with idiopathic megacolon.

Procedure
Colonic smooth muscle strips were suspended in physiologic buffer solution, attached to isometric force transducers, and contracted with acetylcholine (ACh; 10−9 to 10−4M), substance P (SP; 10−10 to W−6M), cholecystokinin (CCK; 10−11 to 10−6M), potassium chloride (KCI; 10 to 80 mM), or electrical field stimulation (EFS; 25 V, 1 to 30 Hz, 0.5-millisecond duration). Isometric stress responses were compared with those obtained from healthy controls. Colonic smooth muscle strips were also evaluated histologically for neuronal and smooth muscle cell morphology.

Results
Passive isometric stress was not altered, but the active isometric stress responses of megacolon smooth muscle to ACh, SP, CCK, KCI, and EFS were significantly (P < 0.05) diminished, compared with healthy controls. Differences were observed in longitudinal and circular smooth muscle from proximal and distal portions of the colon. Histologic evaluation revealed few abnormalities of smooth muscle cells or of myenteric or submucosal plexus neurons. The contractile response of megacolon smooth muscle to EFS, and the inhibition of this response by tetrodotoxin, suggest that myenteric and submucosal plexus neurons in megacolon smooth muscle are functional.

Conclusions
Idiopathic megacolon is a generalized dysfunction of colonic smooth muscle in cats. The diminished isometric stress responses to receptor occupancy (ACh, SP, and CCK) and membrane depolarization (KCI) further suggest that the disorder involves disturbance in the activation of smooth muscle myofilaments. (Am J Vet Res 1996;57:580-587)
Protection of BALB/c mice against homologous and heterologous species of Brucella by rough strain vaccines derived from Brucella melitensis and Brucella suis biovar 4
Authors: Winter Alexander J. , Schurig Gerhardt G. , Boyle Stephen M. , Sriranganathan Nammalwar , Bevins Julia S. , Enright Fred M. , Elzer Philip H. , Kopec John D. 
Published: January 2024

Abstract

Objective
To evaluate stable rough mutants derived from Brucella melitensis 16M and B suis 2579 (biovar 4) as vaccines against homologous and heterologous Brucella spp in the BALB/c mouse model.

Design, Animals, and Procedure
Rough mutants VTRM1 and VTRS1 were obtained from B melitensis 16M and B suis 2579, respectively, by allelic exchange of the rfbU gene encoding mannosyltransferase with a Tn5-disrupted rfbU gene. Mice were vaccinated with VTRM1 or VTRS1 and challenge exposed 8 weeks later.

Results
VTRM1 and VTRS1 replicated extensively in the spleen during the first 3 weeks of infection, then decreased rapidly. Antibodies specific for the O polysaccharide were not detected in sera of mice inoculated with either rough strain. Vaccination with VTRM1 or VTRS1 induced protection against virulent strains of B abortus (2308), B melitensis (16M), B suis biovar 1 (750), and B suis biovar 4 (2579). VTRM1 also protected against B ovis (PA) and against 4 field isolates of B abortus from bison or elk. VTRS1 conferred protection against 4 field isolates of B suis biovar 4 from reindeer. Vaccines prepared from live VTRM1 or VTRS1 provided significantly greater protection than that afforded by vaccines of killed cells in QS- 21 adjuvant. Vaccination with VTRM1 containing VTRS1 gave minimal protection against the antigenically unrelated Listeria monocytogenes, thus demonstrating the immunologic specificity of protection against Brucella spp.

Conclusions and Clinical Relevance
Results encourage evaluation, in primary host species, of VTRM1 and VTRS1, along with RB51, as alternative vaccines to strain 19, Rev 1, or other smooth phase vaccines. (Am J Vet Res 1996; 57:677–683)
Influence of adrenergic and cholinergic mediators on the equine jejunum in vitro
Authors: Malone E. D. , Brown D. R. , Trent A. M. , Turner T. A. 
Published: January 2024

Abstract

Objective
To characterize the response of equine jejunal smooth muscle to adrenergic and cholinergic mediators.

Design
Evaluation of myogenic responses, using an in vitro model.

Sample Population
Intestinal tissues were obtained from horses without gastrointestinal tract disorders or systemic disease.

Procedure
Baseline myogenic tone and amplitude and frequency of contraction were determined for suspended jejunal muscle strips. The level of adrenergic and cholinergic regulation was assessed, using atropine and adrenoceptor antagonists. The response of the muscles to norepinephrine was characterized, using adrenergic blockade and α- and β-agonists.

Results
Adrenergic and cholinergic blockade had minimal effect on baseline myogenic activity. However, α1- and β2-agonists induced significant (P < 0.05) decreases in the amplitude and frequency of contraction. Surprisingly, α2-agonists caused an increase in the contraction amplitude of longitudinal muscle fibers (neurogenic in origin). Change in circular muscle activity was not induced by α2-agonists. Norepinephrine induced a similar selective response and was inhibited by yohimbine.

Conclusions
Baseline jejunal activity appears to be myogenic in origin and can function independently of sympathetic and parasympathetic input. However, intestinal smooth muscle can be affected by adrenergic agonists and potentially by increased concentrations of circulating catecholamines. Norepinephrine may act by altering the activity of other neurotransmitters. Differing responses between circular and longitudinal muscle fibers indicates a need to evaluate both components.

Clinical Relevance
Selective α2-agonists may be potentially useful for motility modification of the equine jejunum. Therapeutic use of adrenergic blockade will be effective only in cases of increased adrenergic stimulation. (Am J Vet Res 1996;57:884–890)
Use of detergent to prevent initial responses to endotoxin in horses
Authors: Longworth Kim E. , Smith Barbara L. , Staub Norman C. , Steffey Eugene P. , Serikov Vladimir B. 
Published: January 2024

Abstract

Objective
To determine whether a detergent can prevent most of the early effects of IV infusion with Escherichia coli endotoxin (< 100 ng/kg of body weight) in horses: marked pulmonary hypertension, acute leukopenia, and fever.

Animals
8 healthy adult horses (4 male, 4 female), 415 to 615 kg.

Design and Procedure
Control and detergent experiments were performed in each horse while it was awake but sedated. In control experiments, 10 to 100 ng of E coli endotoxin/kg was given. In detergent experiments, 100 mg of detergent/kg was given 1 hour before injecting endotoxin, similar to the control experiments.

Results
In control experiments, pulmonary arterial pressure increased transiently over 40 minutes by 33 ± 8 mm of Hg (mean ± SD; P < 0.001), then returned to baseline. Circulating leukocytes decreased to 47 ± 19% (P < 0.02) of baseline by 1 hour after endotoxin, then increased above baseline by 6 hours. Rectal temperature increased by 0.7 ± 0.4 C (P < 0.01). In detergent experiments, the increase in pulmonary arterial pressure was much less than that in the control experiments (8 ± 7 mm of Hg; P < 0.001). Circulating leukocytes did not decrease, and the increase in rectal temperature after endotoxin was blocked.

Conclusions
This attenuation of the response to endotoxin may occur because the normal steps in the response of pulmonary intravascular macrophages (ie, endocytosis of endotoxin and subsequent release of inflammatory mediators) are altered by the detergent. This low-technology, inexpensive, and safe treatment could be an important new clinical tool for veterinarians in combating endotoxemia. (Am J Vet Res 1996;57:1063–1066)
Ontogeny of epinephrine, norepinephrine, dopamine-β-hydroxylase, and chromogranin A in the adrenal gland of pigs
Authors: Laroche Sabine M. , Pinxteren Jef A. , Van Reempts Patrick J. , De Potter Werner P. , Weyns André A. , Verhofstad Albert A. , Van Acker Karel J. 
Published: January 2024

Abstract

Objective
To obtain data on the ontogeny of catecholamines and other chromaffin vesicle components, which could serve as a basis for the study of their role during fetal life in normal and pathologic conditions.

Design
Epinephrine, norepinephrine, dopamine-β-hydroxylase, and chromogranin A contents were measured in the porcine adrenal gland during various stages of gestation.

Animals
934 porcine fetuses representing 22 gestational ages between 43 and 108 days.

Procedure
Total homogenates of adrenal glands were extracted and contents of different neurochemical markers were measured, using high-performance liquid chromatography, immunoassays, and western blotting. Immunohistochemical studies also were performed.

Results
Epinephrine and norepinephrine contents as a function of gestational age can be represented by a sigmoidal curve. Norepinephrine content rises early in gestation, whereas epinephrine content increases later. Maximal increase was significantly higher for epinephrine content. A progressive appearance of separate epinephrine- and norepinephrine-storing cells was documented. Dopamine-β-hydroxylase content as a function of gestational age can be adequately represented by a parabolic curve. No quantitative changes in chromogranin A concentration were observed, but western blotting revealed qualitative changes with progressing gestational age.

Conclusions
Important changes occur in catecholamine formation around day 60 of gestation. The sharp increase in epinephrine/norepinephrine contents and the appearance of separate epinephrine- and norepinephrine-storing cells may be related to the progressive splanchnic innervation of the adrenal gland. The presence of chromogranin A early in gestation may indicate its necessity for catecholamine storage. (Am J Vet Res 1996;57:1074–1079)
Effect of nasal occlusion on tracheal and pharyngeal pressures in horses
Authors: Holcombe Susan J. , Derksen Frederik J. , Stick John A. , Robinson N. Edward , Boehier Deborah A. 
Published: January 2024

Abstract

Objective
To compare tracheal and pharyngeal inspiratory and expiratory pressures achieved during 60 seconds of nasal occlusion in standing horses with pressures achieved in horses during intense exercise.

Animals
5 Standardbreds.

Procedure
Tracheal and pharyngeal inspiratory and expiratory pressures were obtained from 5 horses during 60 seconds of nasal occlusion and compared with tracheal and pharyngeal pressures achieved during incremental treadmill exercise tests in which horses ran at 50, 75, and 100% of the speed that resulted in maximal heart rate ( HRmax)

Results
Significant difference was not detected between peak tracheal inspiratory pressure during nasal occlusion and peak tracheal inspiratory pressure at HRmax. Peak pharyngeal inspiratory pressure was sig nificantly more negative, and peak tracheal and peak pharyngeal expiratory pressures were sig nificantly more positive during 60 seconds of nasal occlusion than those observed in horses running at HRmax.

Conclusion
During upper airway endoscopy in standing horses, 60-second nasal occlusion induced tracheal and pharyngeal inspiratory pressures that equaled or exceeded pressures achieved during high-intensity exercise.

Clinical Relevance
Nasal occlusion is useful to simulate upper airway pressures achieved during high-intensity exercise. (Am J Vet Res 1996;57:1258–1260)