Biomedical subjects

B J Houston

Publications and source records attributed to B J Houston.

4 recordsLinked to original sources

PubMed1995

Arrhythmia prevalence during ambulatory electrocardiographic monitoring of beagles.

Ambulatory ECG, approximately 18 to 24 hours in duration, were obtained from 113 male and 115 female clinically normal, purpose-bred Beagles. The ECG analyzed semi-automatically (44 males, 46 females) were evaluated for heart rate, ventricular ectopic complexes (VEC), bradycardia, and sinus pause; those analyzed by visual inspection (69 males, 69 females) were evaluated for VEC, second-degree atrioventricular block, and supraventricular escape complexes. Mean heart rate was highest at times of maximal human contact (eg, feeding, cleaning) and lowest at periods of no human contact. Bradycardia was observed in 27 of 44 males (61.4%) and 18 of 46 females (39.1%). Sinus pause was identified in 33 of 44 males (75%) and 30 of 46 females (65.2%). Frequency of bradycardia and sinus pause tended to vary inversely with mean heart rate. Ventricular ectopic complexes were detected in 18.8 to 26.1% of the ECG analyzed by use of either method. Although VEC runs and bigeminy were observed, most VEC were single and occurred sporadically. Second-degree atrioventricular block was observed in 6 of 69 males (8.7%) and 14 of 69 females (20.3%); episodes often were single and occurred sporadically. Supraventricular escape complex occurred in 2 of 69 females (2.9%). Multiple types of abnormal complexes were observed in 2 of 69 males (2.9%) and 6 of 69 females (8.7%). Among clinically normal Beagles, ambulatory electrocardiography detects a higher percentage of dogs with VEC, second-degree atrioventricular block, and supraventricular ectopic complexes than does resting electrocardiography.

Animals↗

PubMed1993

Toxicity of CI-949, a novel anti-allergy agent.

The toxicity of CI-949, an effective inhibitor of allergic mediator release in pharmacology models, was evaluated in rodents and dogs. Median lethal doses at 24-hr postdose ranged from 343 to 453 mg/kg in mice and 806 to 2058 mg/kg in rats. Delayed toxicity was observed at 300 mg/kg and greater in mice and at 500 mg/kg and greater in rats. Mortality and clinical intolerance occurred in rats at 200 and 400 mg/kg in the subacute studies, and at 100 and 150 mg/kg in the 13-week study. In rats, dose-dependent lymphoid tissue atrophy and depletion or necrosis of lymphocytes in lymphoid tissues were seen in deaths and moribund terminations. Although doses up to 60 mg/kg administrated for 2 weeks to dogs were well tolerated, 60 and 120 mg/kg in the 13-week dog study were poorly tolerated. Cutaneous sores, mucocutaneous purulent discharge, emesis, diarrhea, and weight loss were identified at these lethal doses. Histopathologic changes in dogs included myocardial, vascular and soft tissue inflammation, and gastric ulceration at 60 and 120 mg/kg, and thymic atrophy at 20 mg/kg and greater. Doses of 10 and 50 mg/kg were no-effect doses in 13-week repeated dose studies in dogs and rats, respectively. These results were used to support initial human clinical trials of CI-949.

Administration, Oral↗

PubMed1993

Characterization of cardiac alterations in nonsedated cynomolgus monkeys.

Spontaneous variations in ECG and continuous Holter monitor recordings of a colony of 31 male and 31 female cynomolgus monkeys were characterized. Electrocardiograms recorded for approximately 1 minute on 2 occasions in nonsedated monkeys were analyzed, and intervals (PR, QRS, and QT), amplitudes (P, Q, R, and T), and heart rate were determined from lead II of these tracings. In addition, Holter monitor recorders were placed on monkeys by use of carrying jackets for 16 to 24 hours of continuous recording twice during the study, and tapes were analyzed. Mean heart rate and intervals and amplitudes were similar for males and females on the first and the second recordings. Mean heart rate for males and females was 232 and 226 beats/min (bpm), respectively. The PR, QRS, and QT interval measurements, 77, 29, and 165 milliseconds, respectively, were recorded for males and 81, 30, and 162 milliseconds, respectively, were recorded for females. The P, Q, R, and T wave amplitudes were 0.16, 0.11, 0.64, and 0.28, mV respectively, for males and were 0.17, 0.10, 0.79 and 0.24 mV, respectively, for females. In addition, ventricular ectopic beats were observed in ECG from 5 females, but not in ECG from the males. Single ventricular ectopic beats were observed in 3 females for either the first or second tracing. One monkey had ectopic beats in both tracings, but in both instances, the number of ectopic beats was low (3 singles in the first and 1 in the second tracing).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Polyarteritis in a beagle.

A 13-month-old Beagle became anorectic and had fever, stiff gait, and tenderness in the inguinal region. Clinical signs of disease were associated with neutrophilia and a decrease in the albumin-to-globulin ratio. The dog became clinically normal for 5 days after 3 days of treatment with penicillin G and dihydrostreptomycin. Clinical signs of disease recurred, and the dog was euthanatized after failing to respond to administration of a trimethoprim-sulfamethoxazole combination for 9 days. Disseminated arteritis was seen in the testes, epididymides, mesentery, coronary arteries, aorta, and thyroid gland. Lesions were seen in large and medium-sized arteries and varied from acute necrotizing arteries to a chronic lesion with organization and recanalization of thrombi. The clinical signs of disease resembled those of Beagle pain syndrome, described in laboratory Beagles.

Animals↗