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Biomedical subjects

G Allan

Publications and source records attributed to G Allan.

At least 91 records · Page 5Linked to original sources
PubMed1989

Studies of the effect of recombinant human-alpha 1 interferon on experimental parainfluenza type 3 virus infections of the respiratory tract of calves.

The effect of the administration of recombinant human interferon on the severity of clinical disease and the extent of pneumonic lesions in calves infected experimentally with bovine parainfluenza 3 (PI3) virus was studied in two experiments. In the first, three pairs of calves aged seven to 10 days were used; one of each pair was injected intramuscularly with 10(6) units of interferon/kg bodyweight for three consecutive days, and the other was left untreated. On the day after the first injection of interferon all the calves were challenged with PI3 virus, a different dose being administered to each pair. There was no evidence of any protective effect from the treatment with interferon. The second experiment used eight, six-week-old calves; four were inoculated in the same way with interferon and all the calves were challenged with the same dose of PI3. Again, there was no evidence of a reduction either in the severity of clinical disease or in the extent of lung consolidation in the calves treated with interferon.

Animals↗
PubMed1989

An improved ELISA and serum neutralisation test for the detection of turkey rhinotracheitis virus antibodies.

The development of a double-well ELISA test for the detection of turkey rhinotracheitis (TRT) virus antibody in turkey and chicken sera, utilising a streptavidin-biotin detection protocol is described. This test was compared with a conventional ELISA, which detects antibody using a peroxidase-labelled anti-turkey IgG. The double-well streptavidin-biotin ELISA was more sensitive than the conventional ELISA, and, due to the consistently low background values obtained, was further modified to a single-well ELISA test. Antibody titres obtained using the single-well streptavidin-biotin ELISA were similar to those obtained using the conventional ELISA. A microtitre serum neutralisation test for TRT virus read using an indirect immunoperoxidase (IIP) detection protocol after 48 h was also developed and compared to the standard neutralisation test employing a 7 day incubation and read by CPE. The specificity of the single-well streptavidin-biotin ELISA was confirmed using the rapid (IIP) serum neutralisation test.

Animals↗
PubMed1988

Cardiac and renovascular effects in the anaesthetized dog of BW A575C: a novel angiotensin converting enzyme inhibitor with beta-adrenoceptor blocking properties.

1. In the anaesthetized open-chest dog, BW A575C (N-(1-(S)-carboxy-5-[4(3- isopropylamino-2-(R,S)-hydroxypropoxy)indole-2- carboxamido]pentyl)-(R,S)-alanyl-(S)-proline) causes a dose-dependent inhibition of the isoprenaline response (increased cardiac rate). In this preparation BW A575C is approximately 50 times less active than propranolol, and 500 times less active than pindolol at the cardiac beta 1-adrenoceptor. 2. At equieffective cardiac beta 1-adrenoceptor blocking doses in the anaesthetized, open-chest dog, BW A575C (5.0 mg kg-1, i.v.) significantly reduces diastolic blood pressure and reduces cardiac contractility and rate. By contrast, propranolol (0.1 mg kg-1, i.v.) and pindolol (0.01 mg kg-1, i.v.) have little effect on diastolic blood pressure, but significantly reduce cardiac contractility and rate. The effects of BW A575C on cardiac rate are not significantly different from those of propranolol and pindolol, but its effects on cardiac contractility are significantly less than those of propranolol. BW A575C also produces some increase in left ventricular internal dimensions at end-diastole. This small cardiac dilatation is not significantly different from that observed with pindolol but is significantly less than that of propranolol. 3. In the anaesthetized closed-chest dog, BW A575C causes a dose-dependent inhibition of the angiotensin I pressor response. In this preparation BW A575C is approximately equiactive with enalapril at preventing the pressor response due to conversion of exogenous angiotensin I to angiotensin II (inhibition of angiotensin converting enzyme (ACE)). 4. At equieffective ACE-inhibition doses in the anaesthetized, closed-chest dog, BW A575C (1.0 mg kg-1 by i.v. infusion) significantly reduces diastolic blood pressure, cardiac contractility and rate, whereas enalapril (1.0 mg kg-1 by i.v. infusion) only significantly reduces diastolic blood pressure. This blood pressure lowering effect of enalapril is not significantly different from that of BW A575C. In this preparation BW A575C and enalapril also significantly increase renal blood flow, and renal excretion of urine and Na+. There is however no significant difference between their renovascular effects. 5. These studies demonstrate that BW A575C produces changes in cardiac and renovascular function which can be ascribed to its being an ACE-inhibitor and a beta-adrenoceptor blocking agent. The combination of these pharmacological properties results in a fall in blood pressure without compromising either cardiac performance or renal function.

Adrenergic beta-Antagonists↗
PubMed1988

A comparative study of the cardiovascular and biochemical actions of the imidazo [4,5b] pyridine sulmazole and an imidazo [4,5c] pyridine analogue, BW A746C.

1. BW A746C is a chemical analogue of the imidazo [4,5b] pyridine, sulmazole (AR-L115 BS). Like sulmazole, BW A746C possesses positive inotropic and vasodilator activity in vivo. 2. In anaesthetized guinea-pigs, dogs and primates, a bolus i.v. injection of BW A746C, (0.001-1.0 mg kg-1) caused a significant, dose-related increase in ventricular dP/dt, and reduction in diastolic blood pressure, with small increases in heart rate. In these species, a significantly higher dose of BW A746C was required to lower blood pressure by 30% from basal, than was needed to raise ventricular dP/dt by 50% over basal. 3. In anaesthetized guinea-pigs and dogs, bolus i.v. injections of sulmazole (0.1-10.0 mg kg-1) caused similar effects to those observed with BW A746C. In these species, however, there was no significant difference between the dose of sulmazole required to lower blood pressure by 30% from basal and that required to raise ventricular dP/dt by 50%. 4. In conscious dogs, i.v. infusion of BW A746C (to a total dose of 0.3 mg kg-1) caused a significant increase in ventricular dP/dt, but no significant change in either diastolic blood pressure or heart rate. 5. In cell-free biochemical assays, there were no clear differences between the observed activities of BW A746C and sulmazole. Both compounds are cyclic nucleotide phosphodiesterase inhibitors with similar potencies and selectivities for the Type III enzyme (IC50 BW A746C = 3.0 +/- 0.5 X 10(-5) M, sulmazole 5.0 +/- 1.9 X 10(-5) M). The compounds had little or no effects on sarcolemmal Na+/K+-ATPase, Ca2+ ATPase or Na+/Ca2+ exchange, and sulmazole, but not BW A746C, had a small, stimulatory effect on myofibrillar ATPase. 6. In anaesthetized guinea-pigs and dogs, BW A746C was significantly more potent as a positive inotrope than sulmazole. In contrast with sulmazole, BW A746C produced its inotropic effects at significantly lower doses than those required to reduce diastolic blood pressure. This was also apparent from the results obtained in the anaesthetised primates and the conscious dogs. It was therefore concluded that the inotropic/vasodilator profile of BW A746C favours its positive inotrope activity. This profile cannot be explained on the basis of any biochemical differences from sulmazole.

Animals↗