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Biomedical subjects

C J McGrath

Publications and source records attributed to C J McGrath.

17 recordsLinked to original sources
PubMed1992

Effect of tiletamine/zolazepam sedation on intradermal allergy testing in atopic dogs.

Seven atopic dogs underwent intradermal allergy testing with 46 inhalant antigens before and after administration of a tiletamine/zolazepam solution (4 mg/kg of body weight, IV). This anesthetic protocol had no significant effect on the intradermal response caused by histamine, whole flea extract, or various inhalant allergens. Short-acting chemical restraint induced by the drug combination facilitated the intradermal testing procedure.

Animals↗
PubMed1991

BAY K 8644 and nifedipine alter halothane but not caffeine contractures of malignant hyperthermic muscle fibers.

The purpose of these experiments was to determine if the Ca2+ agonist BAY K 8644 and the Ca2+ antagonist nifedipine alter the mechanical responses of malignant hyperthermia-susceptible (MHS) skeletal muscle to halothane and caffeine. Muscle fiber bundles were dissected from MHS porcine skeletal muscle and exposed to BAY K 8644 (10 microM), nifedipine (1 microM), low-Ca2+ media [Ca2+ replaced by 1 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid], or diltiazem (30 microM) administered alone and with halothane (3%) or caffeine (0.5-0.8 mM). When administered alone, both halothane and BAY K 8644 evoked a significant change in resting tension (i.e., contracture) of 193.7 +/- 61.0 and 51.9 +/- 21.5 mN/cm2, respectively. When administered in combination, BAY K 8644 had no effect on the magnitude of the halothane contracture (195.2 +/- 58.6 mN/cm2) but reduced its onset time from 306.7 +/- 36.3 to 105.9 +/- 8.9 s. Nifedipine, low Ca2+, and diltiazem significantly reduced the halothane contracture (103.1 +/- 30.3, 123.1 +/- 20.6, and 112.6 +/- 16.2 mN/cm2, respectively) but had no effect on its onset time. In addition, low Ca2+ reduced the magnitude of the BAY K 8644 contracture (8.2 +/- 2.1 mN/cm2). BAY K 8644 also increased contractures induced by low caffeine concentrations (0.5-2.0 mM) but did not alter contractures induced by 4.0 and 8.0 mM caffeine, whereas nifedipine, low Ca2+, and diltiazem had no effect on these contractures. These results suggest that extracellular Ca2+ influx may have some influence on halothane but not on caffeine contractures of MHS skeletal muscle.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1990

Adaptation of human oscillometric blood pressure monitors for use in dogs.

Two digital oscillometric human blood pressure measuring devices were modified and evaluated as blood pressure monitors in 12 healthy anesthetized dogs. Direct arterial pressures were measured via cannulation of the dorsal pedal artery and were correlated with indirect measurements through an inflatable cuff placed over the dorsal pedal artery below the hock joint of the contralateral limb. Direct and indirect measurements were compared for systolic, diastolic, and calculated mean arterial pressures. Blood pressure ranges between 215/145 mm of Hg and 65/30 mm of Hg were obtained, using combinations of halothane, phenylephrine, calcium, and IV administered fluids. Machine A was found to be insufficient for clinical application, on the basis of correlation coefficients between direct and indirect pressures of 0.78, 0.65, and 0.74 for systolic, diastolic, and mean arterial pressures, respectively. Higher correlation coefficients between direct and indirect pressures (0.77, 0.87, and 0.87, respectively) were obtained with machine B. The results of the study reported here suggest machine B may be an effective blood pressure monitoring device in anesthetized dogs.

Animals↗
PubMed1988

Alpha-chloralose as a capture and restraint agent of birds: therapeutic index determination in the chicken.

The median effective dose for capture (ED50) and the median lethal dose (LD50) of alpha-chloralose given orally to domestic chickens (Gallus domesticus) were determined by probit analysis to be 45 mg/kg and 300 mg/kg, respectively. The therapeutic index (TI = LD50/ED50) was 6.7. This indicates that alpha-chloralose is only a marginally safe capture agent in domestic species and particularly in field applications involving other wild avian species in which the amount of the drug ingested by an individual bird is not controlled.

Administration, Oral↗
PubMed1986

Anesthetic techniques in poultry.

Anesthesia may be required in various species of poultry to facilitate surgery, diagnostics, and research. Preanesthetic evaluation, careful anesthetic management, and proper supportive methods should be employed. Injectable regimens may be useful for some procedures, but inhalation methods are more appropriate for long periods of anesthesia. Intubation of the trachea and maintenance of ventilation are of particular importance in avian species. Monitoring and support should continue until recovery is complete.

Anesthesia↗
PubMed1985

Effect of verapamil on cardiac chronotropic response to vagal stimulation in neonatal pigs.

The effects of verapamil on the chronotropic response to vagal stimulation in young pigs anesthetized with sodium pentobarbital (30 mg/kg of body weight, intraperitoneally) was evaluated. After bilateral vagotomy, the administration of verapamil (loading dose of 100 micrograms/kg, followed by 2 micrograms/kg/min infusion) resulted in a significant (P less than 0.05) reduction in heart rate (HR) and mean arterial blood pressure. Cardiac frequency responses to vagal stimulation were obtained by stimulating the distal end of the right vagus nerve at selected frequencies (5, 10, 15, and 20 Hz) with supramaximal voltage (10 to 15 V) and constant duration (2 ms). The HR was measured after 15 s at each level of stimulation. The slopes of decrease in HR to the frequency of vagal stimulation were significantly (P less than 0.05) reduced after verapamil as compared with its controls. After atropine (0.5 mg/kg), the vagally induced tachycardia was partially attenuated by verapamil, but was completely eliminated by beta blockade with propranolol (1 mg/kg). These findings indicated that verapamil may influence the parasympathetic control of the heart in young pigs.

Animals↗
PubMed1979

Serum and urine inorganic fluoride concentrations and urine oxalate concentrations following methoxyflurane anesthesia in the dog.

Plasma fluoride, urine fluoride and urine oxalate concentrations were measured before administering an anesthetic to 8 dogs, and at 0, 3, 9, 24, 48, and 72 hours following 1.5 hours of anesthesia with 1% methoxyflurane. Plasma and urine osmolalities were measured and compared with fluoride and oxalate values. Fluoride concentration increased in both plasma and urine following anesthesia when compared with the preanesthetic concentrations. Maximum mean plasma inorganic fluoride was 106.71 mumoles per liter (+/- 25.44 SE) at 9 hours after exposure to methoxyflurane was completed. By 72 hours after exposure to methoxyflurane the plasma fluoride concentration was 23.47 microM/L (+/- 5.74 SE). Mean urine inorganic fluoride concentration was highest at 9 hours after exposure to methoxyflurane and reached 6047.03 microM/L (+/- 1378.46 SE) as compared to the mean preanesthetic base-line concentration of 542.68 microM/L (+/- 132.93 SE), and the 72 hour mean urine fluoride concentration which was 1593.78 microM/L (+/- 579.46 SE). Urine oxalate concentrations, when compared with urine osmolality (mg/mOsm), increased throughout the study. The 72-hour concentration after exposure to methoxyflurane was 2.5 times the preanesthetic (mg/mOsm) oxalate concentration. Plasma osmolality did not change markedly during the study. Urine osmolalities varied between animals and collection times, but a consistent pattern did not occur. Clinical and laboratory signs of renal dysfunction were not observed in any animal during the study.

Anesthesia↗
PubMedDate not supplied

Equine post-anesthetic lameness. A retrospective study.

The incidence of post-anesthetic lameness in 655 horses undergoing 733 anesthetic episodes over a 3 year period was 6.4%. Nineteen factors previously reported or proposed to play a role in the development of post-anesthetic lameness were evaluated statistically. Only hypotension and the duration of the anesthetic period were significant factors.

Age Factors↗
PubMedDate not supplied

Autonomic and cardiovascular effects of neuromuscular blockade antagonism in the dog.

Autonomic and cardiovascular changes were studied when neuromuscular blockade was antagonized in 96 dogs with one of eight anticholinesterase-antimuscarinic drug combinations. Neostigmine (50 or 100 micrograms/kg) was administered before or after atropine (40 micrograms/kg) or glycopyrrolate (10 micrograms/kg). The high dose of neostigmine (100 micrograms/kg) caused bradyarrhythmias, salivation, and signs of bronchosecretion when used with either antimuscarinic agent and irrespective of the administration sequence. The heart rate increased, but not significantly, when atropine was injected before either dose of neostigmine. This did not occur when this administration sequence was reversed. Arrhythmias and cardiovascular and autonomic changes did not occur when glycopyrrolate was injected before or after neostigmine at 50 micrograms/kg.

Animals↗
PubMedDate not supplied

Preanesthetic evaluation and management of malignant hyperthermia in the pig experimental model.

Fifty-three swine from the University of Missouri Sinclair Medical Research Farm were used in experimentation to determine their susceptibility to malignant hyperthermia, to determine appropriate anesthetic agents for susceptible swine and to investigate appropriate pharmaceutical agents which could protect against the development of malignant hyperthermia. The screening technics used were successful in determining susceptible animals to MH and the anesthesia studies indicated that dissociative anesthetics had less tendency to trigger MH than did halothane and pancuronium was shown to have greater safety as a muscle relaxant than succinylcholine in this group of pigs. Pigs pretreated with reserpine had less tendency to develop symptoms of MH and some were completely protected. The principle undesirable effect was the development of hypotension if sufficient reserpine was used to provide total protection.

Anesthetics↗