bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pharmacokinetics of the active metabolite of benazepril, benazeprilat, and inhibition of plasma angiotensin-converting enzyme activity after single and repeated administrations to dogs
Authors: King Jonathan N. , Mauron Catherine , Kaiser Günther 
Published: January 2024

SUMMARY
Plasma pharmacokinetic variables of benazeprilat, the active metabolite of the angiotensin-converting enzyme (ace) inhibitor benazepril, were evaluated in healthy Beagles. Benazeprilat was administered iv at a dosage of 0.5 mg/kg of body weight (n = 9). The elimination half-life of benazeprilat was 3.5 hours, although an additional terminal phase was observed in some dogs. Vehicle (gelatin capsules) or benazepril at dosages of 0.125, 0.25, 0.5, or 1.0 mg/kg was administered orally as a single administration, then once daily for 15 consecutive days (n = 5 or 6/group). Peak benazeprilat concentrations were rapidly attained by 2 hours. Benazeprilat concentrations accumulated moderately with repeated administration, with a peak concentration that was 23% higher and an area under the concentration-time curve that was 34% higher after the 15th dose of benazepril, compared with values after a single dose. The effective half-life for accumulation for all 4 dosages was 12 hours. Steady-state concentrations at 2 hours after administration were achieved after a median (range) of 1 (1 to 6) dose(s).
Pharmacodynamic variables were assessed by measurement of plasma ace activity after oral administration of benazepril or vehicle. All dosages of benazepril caused profound inhibition of ace, with rapid onset of activity (time to peak effect, 2 hours) and long duration of action (single administration of all 4 doses induced inhibition of ace that was significantly different from the value in the control [vehicle-treated] dogs for all time points between 1 and 30 hours). Maximal inhibition at all time points was induced by the 0.25- mg/kg dosage at a single administration and with the lowest dosage tested (0.125 mg/kg) at steady state. At steady state, the 0.25-mg/kg dosage caused (mean ± sem) 96.9 ± 2.0% inhibition of ace activity at maximal effect and 83.6 ± 4.2% at trough effect (24 hours after dosing), indicating minimal variation in peak/trough effect. Steady-state inhibition of ace activity at both peak and trough drug effect was achieved after 1 to 4 doses. The data indicate that benazepril is a potent and long-acting ace inhibitor in dogs.
Effects of tendon grip technique (frozen versus unfrozen) on in vitro surface strain measurements of the equine deep digital flexor tendon
Authors: Matthews Gloria L. , Keegan Kevin G. , Graham Huber L. 
Published: January 2024

Abstract

Objective
To determine effects of tendon grip technique on in vitro surface strain measurements of equine deep digital flexor tendon (DDFT) when loaded in tension.

Sample Population
12 hind limb DDFT from 8 adult horses (mean age, 9.8 years [range, 4.5 to 17 years]; mean body weight, 472 kg [range, 450 to 509 kg]), with no clinical evidence of hind limb lameness.

Design and Procedure
After calibration, liquid mercury strain gauges were sutured to plantar surfaces of the tendons at distal (position 1), middle (position 2), and proximal (position 3) metatarsal regions. Each tendon was affixed to a materials testing machine (distally by the distal phalanx, and proximally by a metal clamp), and loaded once in tension, at a strain rate of 2.8 to 3.0%/s, to 3% clamp displacement. Liquid nitrogen was used to freeze the proximal ends of 6 tendons before placement in the clamp. Proximal ends of the remaining 6 tendons were left unfrozen. Surface strains were determined with the aid of low-resistance bridge circuits. Data were analyzed at time points corresponding to 1, 2, and 3% clamp displacement.

Results
Mean surface strains of tendons with frozen ends were significantly greater than those for tendons with unfrozen ends, and closer to strain measured by clamp displacement, at 1 and 2% clamp displacement. This difference was present but not significant at 3% clamp displacement. Mean local surface strain was not significantly different between the 3 gauge positions.

Conclusions
Freezing tendon ends is a useful technique to increase measured surface strains in equine DDFT, thereby making them closer to universal strain as measured by clamp displacement, and, thus, more likely to represent true surface strain. (Am J Vet Res 1996;57:111-115)
Demonstration of synergistic effects of sulfonamides and dihydrofolate reductase/thymidylate synthase inhibitors against Neospora caninum tachyzoites in cultured cells, and characterization of mutants resistant to pyrimethamine
Authors: Lindsay David S. , Butler Jamie M. , Rippey Natasha S. , Blagburn Byron L. 
Published: January 2024

Abstract

Objective
To examine the efficacies of combinations of 7 sulfonamides and 5 dihydrofolate reductase/thymidylate synthase (DHFR/TS) inhibitors against tachyzoites of Neospora caninum in cultured cells. Mutant tachyzoites that were resistant to pyrimethamine were produced and examined for resistance to other DHFR/TS inhibitors.

Design and Procedures
After 5 days of treatment, a cell culture flask lesion-based assay was used to determine efficacies of combinations of sulfonamides and DHFR/TS inhibitors against N caninum tachyzoites and to evaluate the sensitivity of pyrimethamine-resistant mutants of N caninum to test agents. Cultured cells that were infected with the appropriate strains of N caninum and treated or not treated (controls) with test agents were examined. Mutations were induced by chemical mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidme or by selection for growth in permissive concentration of pyrimethamine.

Results
Synergism was detected for combinations of pyrimethamine, ormetoprim, trimethoprim, or diaveridine with the sulfonamides. Methotrexate did not have improved efficacy when combined with sulfonamides. Two mutants were produced that were resistant to pyrimethamine. Both mutants were resistant to other DHFR/TS inhibitors. Both mutants remained resistant to pyrimethamine in the absence of continuous exposure to the agent, indicating that the induced resistance was stable. Synergism was detected for combinations of DHFR/TS inhibitors and sulfonamides against these pyrimethamine-resistant mutants.

Conclusions
Combinations of suboptimal concentrations of sulfonamides with suboptimal concentrations of DHFR/TS inhibitors results in improved efficacy of the agents in a cell culture assay. Stable resistance to pyrimethamine can be induced in N caninum tachyzoites by use of chemical mutagenesis or by selection.

Clinical Relevance
In vitro evidence indicated that combination treatment, using sulfonamides and DHFR/TS inhibitors, may be effective in treating neosporosis. (Am J Vet Res 1996;57:68-72)
Reactivity of purified complement component 3b with bovine neutrophils and modulation of complement receptor 1
Authors: Di Carlo Andrea L. , Paape Max J. , Miller Robert H. 
Published: January 2024

Abstract

Objective
To study binding of purified complement component C3b to bovine blood and mammary neutrophils (PMN) after various treatments and determine their ability to modulate receptor numbers.

Design
Cell isolation, activation, and flow cytometric studies.

Animals
Healthy lactating Holstein cattle.

Procedure
Complement component C3b (18,300 kd) was isolated from bovine serum by column chromatography, and flow cytometric assays using fluorescein isothiocyanate-labeled C3b were developed to evaluate binding to PMN complement receptor 1. Multiple substances were tested to determine their overall effect on C3b binding to PMN. Blood and milk PMN were isolated by differential centrifugation and exposed to optimal concentrations of recombinant human C5a, formyl-methyl leucyl phenylalanine, recombinant bovine interferon-γ, variable concentrations of phorbol myristate acetate (0.01 to 100 ng), calcium ionophore A23187, serum-opsonized zymosan, zymosan-activated serum (ZAS), zymosan-activated plasma (ZAP), and hydrocortisone acetate (25 and 70 ng). Additionally, mammary and blood PMN were preincubated in skim milk and whey.

Results
Variable concentrations of phorbol myristate acetate caused a dose-dependent increase in percentage of PMN binding C3b, and increased the amount of C3b bound per cell. Significant increases were observed after PMN treatment with calcium ionophore, serum opsonized zymosan, ZAS, and ZAP; conversely, incubation of PMN with hydrocortisone acetate resulted in reduced overall binding of C3b. Mammary PMN consistently bound more C3b, which was attributed to their activation during migration into the mammary gland. Binding of C3b was inhibited by skim milk. Activation of blood PMN with PMA, ZAS, and ZAP elicited larger responses than those observed for mammary PMN.

Conclusions
Modulation of complement receptors on bovine PMN is possible. Additionally, significant difference between the level of binding of C3b to blood and milk PMN, with milk PMN having higher binding, may be attributable to migration of PMN into the mammary gland, causing increased receptor expression.

Clinical Relevance
Contribution to a greater understanding of the role of complement in bovine immunologic systems, leading to testing for in vivo enhancement of bovine immune responses to invading pathogens.
Induction of protective immunity against transmissible gastroenteritis virus after exposure of neonatal pigs to porcine respiratory coronavirus
Authors: Wesley Ronald D. , Woods Roger D. 
Published: January 2024

Abstract

Objective
To test the ability of porcine respiratory coronavirus (PRCV) to induce protective immunity to antigenically related transmissible gastroenteritis virus (TGEV) in neonatal pigs.

Design
Neonatal pigs were exposed to PRCV when they were 2, 4, or 6 days old and challenge-exposed to virulent TGEV at 10 days of age.

Animals
34 hysterectomy-derived, colostrum-deprived pigs.

Procedure
After challenge exposure, clinical signs were observed, body weight, antibody response, and virus shedding were measured, and mortality was determined.

Results
After exposure to PRCV, principals had a slightly slower rate of weight gain than did controls; with 1 exception (a PRCV-exposed pig that was dyspneic for 1 day), principals and controls remained clinically normal until shortly after challenge exposure, when all pigs became listless and anorectic and developed watery diarrhea. However, by day 3, most of the pigs that had been exposed to PRCV when they were either 2 or 4 days old began to recover and most (15/18) survived. Conversely, the clinical condition of most of the other pigs worsened and most (14/16) died. Pigs exposed to PRCV when they were 2 or 4 days old also differed from all other pigs in that they had serum virus-neutralizing antibodies for PRCV and TGEV at the time of challenge exposure.

Conclusions
The PRCV can induce protective immunity to TGEV in neonatal pigs and such immunity develops at or about 6 days after exposure to PRCV. Moreover, protective immunity may be coincident with the appearance of virus-neutralizing antibody.

Clinical Relevance
Exposure to PRCV should enhance a TGE herd vaccination program.
Transcatheter modification of the atrioventricular node in dogs, using radiofrequency energy
Authors: Wright Kathy N. , Bright Janice M. , Cox James W. , McCracken Malcolm D. 
Published: January 2024

Abstract

Objective
To develop a protocol for reliably inducing atrioventricular (AV) block (ideally first- or second-degree), using radiofrequency energy.

Design
An electrosurgical unit was coupled to an ammeter, which was connected to the distal pole of an electrode catheter positioned at the AV node. Control settings had previously been calibrated to the power output in a circuit with a 100-ohm resistance.

Animals
10 clinically normal dogs.

Procedure
Transcatheter AV nodal modification was attempted, using progressive power applications of 10 to 20 W for progressive durations of 10 to 30 seconds. Atrioventricular nodal conduction and refractivity were measured before and 20 minutes and 1 month after ablation. Electrocardiograms were monitored throughout the 1-month period.

Results
Eight of the 10 dogs developed complete AV block, 1 developed stable 2:1 AV block, and another had no long-term change in AV nodal conduction. Four dogs attained their maximal degree of AV block in 2 to 5 days. Three of these had no AV nodal conduction changes until 2 to 4 days after ablation.

Conclusions
An electrosurgical unit can be economically modified for radiofrequency transcatheter ablation. Stable, incomplete AV block was rarely induced using this protocol, whereas complete AV block often developed. A major finding was frequent delay between energy delivery to the AV nodal region and induction of AV block.

Clinical Relevance
Induction of complete AV block using this technique, followed by permanent pacemaker placement, is an effective alternative to long-term antiarrhythmic treatment in animals with chronic atrial arrhythmias. Transcatheter ablation could be used to treat other forms of tachycardia, as it is in human medicine.
Cross-sectional evaluation of environmental, host, and management factors associated with risk of seropositivity to Ehrlichia risticii in horses of New York state
Authors: Atwill Edward R. , Mohammed Hussni O. , Lopez Jorge W. , McCulloch Charles E. , Dubovi Edward J. 
Published: January 2024

Abstract

Objectives
To locate counties within New York state with a high seroprevalence among the equine population, to determine host, management, and environmental factors that were associated with seropositivity to Ehrlichia risticii, and to determine evidence for arthropod- or helminth-mediated transmission of E risticii to horses.

Design
Cross-sectional study.

Sample Population
A random sample of 3,000 of the 39,000 equine operations in New York state was selected, and 2,587 horses from 511 operations were tested.

Procedure
Blood samples were collected from horses and tested for seropositivity, using the indirect fluorescent antibody technique. Data on each horse and each farm's management were obtained by personal interview. The significance of each factor on the risk of seropositivity was evaluated, using mixed-effect logistic regression.

Results
The seroprevalence among E risticii-nonvaccinated horses was 7.3%. The county-specific seroprevalence ranged from 0 to 27%, with higher-risk counties located at low elevation. Farms at higher risk for having seropositive horses were located predominately at low elevation with no bodies of water nearby.
Risk of seropositivity was associated with time spent in a stall or run-in shed, with frequency of application of fly spray, and, depending on duration of residency at the farm, with frequency of deworming with benzimidazole and pyrantel. Standardbreds were 2 to 3 times more likely to have been exposed, compared with Thoroughbreds. Depending on duration of residency at the farm, male and middle-age horses were at higher risk.
Up to 32% of the variance for a horse to test seropositive for E risticii on the logit scale was attributable to farm-level random effects, but the nested social group random effect was not significant.

Conclusions
Arthropods and helminths may have a role in the transmission of this disease. Several management factors may directly or indirectly modify the risk of exposure to E risticii, allowing for the possibility of additional control measures besides traditional vaccination strategies.(Am J Vet Res 1996;57:278-285 )
Kinetics of the humoral immune response to multiple treatments with exogenous gonadotropins and relation to ovarian responsiveness in domestic cats
Authors: Swanson William F. , Roth Terri L. , Graham Katerina , Horohov David W. , Godke Robert A. 
Published: January 2024

Abstract

Objective
To investigate ovarian responses and kinetics of gonadotropin-binding immunoglobulin production in domestic cats repeatedly treated with equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG) at short or long treatment intervals.

Design
Queens were treated 3 or 4 times with a standard eCG/hCG regimen at short (49 to 57 days) or long (130 to 135 days) intervals and subjected to laparoscopy after each treatment to evaluate ovarian follicular development. Serial serum samples were assessed by ELISA for the presence of eCG-binding immunoglobulins.

Animals
11 clinically normal sexually mature female cats.

Results
Queens repeatedly stimulated with eCG/hCG at long intervals typically had no decrease (P > 0.05) in ovarian follicle production or in maturity of recovered oocytes, whereas queens treated at short intervals had reduced (P < 0.05) follicular development and compromised oocyte maturity by the third stimulation. For both interval groups, ELISA data indicated individual variability in seroconversion after eCG/hCG challenge exposure. In general, queens treated at short intervals had higher peak anti-eCG immunoglobulin titer than did queens treated at long intervals; high titer at the time of eCG/hCG injection, or rapid increases in titer immediately after injection were predictive (P < 0.05) of poor ovarian responses.

Conclusions
Results suggest that individual variability in immune responses and intervals between repeated gonadotropin treatments determine whether queens develop immunologically mediated ovarian refractoriness to exogenous gonadotropins. Intervals of at least 4 months between successive eCG/hCG treatments are recommended for assisted reproductive procedures in domestic and nondomestic cats.(Am J Vet Res 1996;57:302-307)
Involvement of (n-6) essential fatty acids and prostaglandins in liver lipid accumulation in Japanese quail
Authors: Murai Atsushi , Furuse Mitsuhiro , Okumura Jun-ichi 
Published: January 2024

Abstract

Objective
To investigate the involvement of (n-6) essential fatty acids, such as linoleic acid [18:2(n-6)] or γ-linolenic acid [18:3(n-6)], and of prostaglandins on liver lipid accumulation in Japanese quail.

Design
Effects of graded amounts of aspirin, which inhibits prostaglandin synthesis, on liver weight were determined in experiment 1. Experiment 2 was designed to clarify the effect of dietary essential fatty acid sources and inhibition of prostaglandin synthesis on the liver fat and fatty acid profile.

Animals
Female Japanese quail.

Procedure
In experiment 1, from 1 to 3 weeks of age, birds were fed ad libitum the essential fatty acids-free or linoleic acid-adequate (2%) diets with graded amounts of aspirin (0, 0.1, 0.2, and 0.4%). In experiment 2, from 1 to 4 weeks of age, birds were fed the same amount of essential fatty acids-free, linoleic acid-adequate, or γ-linolenic acid (0.4%) diets with (0.2%) or without aspirin.

Results
In experiment 1, in groups given the essential fatty acids-free diet, liver weight increased with an increase in dietary aspirin concentration. In experiment 2, γ-linolenic acid completely prevented liver triacylglycerol and cholesterol accumulation induced by the essential fatty acids-free diet. Aspirin treatment significantly lowered plasma prostaglandin F2α concentration, but did not affect liver lipid concentrations. In groups fed the essential fatty acids-free diets, however, aspirin treatment increased liver weight and liver triacylglycerol concentration by 20 and 40%, respectively.

Conclusions
γ-Linolenic acid or its metabolites, but not linoleic acid itself, are important factors in reducing fatty liver in Japanese quail with the essential fatty acids-deficient condition.(Am J Vet Res 1996;57:342-345)
Impact of an orally administered insect growth regulator (lufenuron) on flea infestations of dogs in a controlled simulated home environment
Authors: Smith Ronald D. , Paul Allan J. , Kitron Uriel D. , Philip John R. , Barnett Sharron , Piel Margaret J. , Ness Robert W. , Evilsizer Melody 
Published: January 2024

Abstract

Objective
To evaluate the ability of lufenuron to control cat flea (Ctenocephalides felis felis) populations on dogs under conditions simulating a naturally infested home environment.

Design
2 treatment and 2 control groups of dogs. Treated dogs received lufenuron in tablet form monthly, and controls received excipient. Dogs had unrestricted access to indoor (carpeted) and outdoor (grassy) environments in which self-propagating flea populations had been established.

Animals
17 adult female Beagles.

Procedure
Dogs were monitored for 77 days after initial infestation with fleas and 70 days after initial treatment. Efficacy of the drug was calculated on the basis of absolute reduction in flea counts and as a percentage of control.

Results
Lufenuron administration caused a statistically significant (P < 0.05) reduction in flea burdens in treated dogs, compared with controls. Initiation of treatment 7 days after infestation resulted in 75% control of F1-generation and 97% control of F2-generation fleas over a 70-day posttreatment period.

Conclusions
Lufenuron was highly effective in reducing flea populations on dogs. The time required for control will vary with the duration (generation time) of the flea reproductive cycle and, hence, the geographic area in which the product will be used. The experimental results are most relevant to use of the product for control of an existing flea population in the Midwest. (Am J Vet Res 1996;57:502–504)
Evaluation of propofol for general anesthesia in premedicated horses
Authors: Mama K. R. , Steffey E. P. , Pascoe P. J. 
Published: January 2024

Abstract

Objective
To evaluate selected hemodynamic, respiratory, and behavioral responses to propofol in horses premedicated with xylazine or detomidine.

Design
Xylazine (0.5 and 1.0 mg/kg of body weight) was administered IV on different days to each of 6 horses prior to IV administration of propofol (2 mg/ kg). In a second group of 6 horses, detomidine (15 and 30 µg/kg) was similarly studied.

Animals
2 groups of 6 mature healthy horses.

Procedure
Rectal temperature, heart and respiratory rates, arterial blood gas tensions, and direct arterial blood pressures were recorded before and at fixed intervals after drug administration. Induction and recovery events were quantitatively and qualitatively assessed. Cardiopulmonary and behavioral data to follow were statistically analyzed (P< 0.05).

Results
Heart rate decreased in dose-dependent manner from a mean (± SD) of 39.5 ± 5.1 beats/min after xylazine and detomidine. Second-degree atrioventricular dissociation was commonly seen at the higher drug doses. After propofol administration, heart rate either transiently increased or was less depressed early in recumbency, compared with predrug values. Direct arterial blood pressures varied inconsistently from predrug values. Mean arterial carbon dioxide tension tended to increase after drug administration (significance variable) from predrug values of 42 to 46 mm of Hg in both drug groups. After xylazine or detomidine administration, arterial oxygen tension decreased significantly from predrug values of 97 to 103 mm of Hg. The magnitude and duration of decrease was dose-dependent and greatest during recumbency.
Behavioral responses to anesthetic induction were variable, but horses were uniformly calm and coordinated during recovery. Recumbency time increased in reponse to the higher dose of either premedicant drug. Mean (± SD) times to standing were 25.02 ± 4.42 and 35.57 ± 6.83 minutes for the low and high doses of xylazine, respectively and 41.04 ± 11.21 and 52.64 ± 14.67 minutes for the low and high doses of detomidine, respectively.

Conclusion
Neither xylazine nor detomidine prevented excitation associated with propofol injection in horses.

Clinical Relevance
Xylazine- or detomidine-propofol combinations likely will not replace common anesthetic induction techniques for horses. However, recovery characteristics associated with propofol encourage further study in horses. (Am J Vet Res 1996;57:512–516)