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Biomedical subjects

A Fisher

Publications and source records attributed to A Fisher.

At least 253 records · Page 14Linked to original sources
PubMed1977

Prevention by drugs of tachyphylaxis at nicotinic receptors in the cat superior cervical ganglion in situ.

A new compound, AF3 (4-ethyl-6-oxa-1-azatricyclo)4.2.2.02,7)dodecan-5-one), and its 4-phenyl analogue, AF6, embodying the structural elements of acetylcholine in a highly rigid framework, were shown to evoke nicotine-like responses in the nictitating membrane (NM) and blood pressure when applied to the superior cervical ganglion in anaesthetized cats. In this respect, their equiactive molar ratio was (nicotine : 1),20-30. However, at doses that were too low to evoke any response, AF3 appeared to potentiate the responses to nicotine or tetra-methylammonium (TMA) by preventing or abolishing tachyphylaxis to the two latter drugs, the effect being dose-dependent with AF3. DMPP which produces much less tachyphylaxis, or preganglionic nerve stimulation, was little or not potentiated in presence of AF3. It is proposed that potentiation to nicotine or TMA occurs following occupancy by AF3 of a regulatory subsite, thereby preventing further access to it by nicotine or TMA. In this respect, AF3 plays the role of a "neutral" molecule.

Animals↗
PubMed1977

Adult coarctation of the aorta: Anaesthesia and postoperative management.

The complications following surgery for the correction of aortic coarctation are reviewed. The immediate postoperative increase in blood pressure is associated with a very high (750%) increase in plasma noradrenaline concentrations. The pre-operative management and preparation of the patient, the use of induced hypotension during surgery with careful haemodynamic control to prevent the hypoperfusion of the lower segment of the aorta, and the postoperative management with special reference to adequate control of blood pressure are discussed.

Adult↗
PubMed1977

Resting tremor in alcoholic brain disease.

Two patients with signs of alcoholic brain disease of the Wernicke-Korsakoff type were found to have an unusual movement disorder manifested basically as a resting tremor. Electrographic recording showed that the tremor wave comprised multiple elements, though the rate of the basic tremor was stable. Though the tremor was qualitatively similar to documented rubral tremor, a mesencephalic lesion could be defined in only 1 patient.

Alcohol Amnestic Disorder↗
PubMed1976

A new probe for heterogeneity in muscarinic receptors: 2-methyl-spiro-(1, 3-dioxolane-4, 3')-quinuclidine.

The title compound (MSDQ) is a new muscarinic agonist related to 3-acetoxyquinuclidine (3-AcQ) but also of a highly rigid structure. In view of this, it may constitute a probe for the detection of heterogeneity among muscarinic receptors. Indeed, equipotent molar ratios (EPMR) for ACh, 3-AcQ and MSDQ were as follows: guinea pig ileum, 1 : 14 : 240; vasodepressor effect in the cat, 1 : 6 : 188. But EPMR for 3-AcQ and MSDQ as stimulants of the superior cervical ganglion in the cat were 1 : 1 and for the induction of tremors in mice, 9 : 5. No such subtle differences in receptor specificity were detected when the probe used was the 2, 2-diphenyl analogue (DiPSDQ) of MSDQ which was a powerful competitive antagonist in all systems, more potent than atropine, but with a CNS/PNS activity of 1.1 compared to 26 for atropine. In view of this, the use of potent antagonists as probes for muscarinic receptor heterogeneity is questionable.

Animals↗
PubMed1976

A study of muscarinic receptor heterogeneity with weak antagonists.

A study of heterogeneity among muscarinic receptors was carried out with new rigid molecules, comprising structures in the fused quinuclidine-valerolactone, quinuclidine-cyclohexenone, quinuclidine-cyclohexanone and quinuclidine-cyclohexane derivatives. These are structurally related to the potent muscarinic agent, 3-acetoxyquinuclidine but substantially different from in it conformation. All proved to antagonize acetylcholine-like activity, but to a different extent in different systems. The equipotent molar ratio with respect to atropine (as 1) was: isolated guinea pig ileum, 10,000-1,000; salivary gland (mouse), 1,000-100; superior cervical ganglion (cat), 100-10; CNS (mouse), approximately 10. It is suggested that the rigid structure induces a three-point constrained fit in the receptor (onium group, hydrophobic moiety and carbonyl group), but that not all muscarinic receptors are capable of responding equally. In this case, receptor specificity of the drug is a direct consequence of its graded departure from the preferred conformation of acetycholine and, therefore, is necessarily associated with partial loss of potency.

Animals↗
PubMed1976

On the visual disturbances associated with massive basal aneurysms.

When massive basal aneurysms compromise the anterior visual pathways the resulting disturbances of vision are diverse and a firm clinical diagnosis is difficult. Because of the rarity of the condition, a critical analysis of the visual defects was made in five personally studied patients with large anterior basal aneurysms in an effort to clarify the clinical features of the disorder. These observations were related to those reported in larger series of patients by Jefferson and Bull. This study gives support to the opinion that the commonest visual defect seen with massive basal aneurysms is impairment of visual acuity, followed next in frequency by bitemporal hemianopia, and then by junction scotoma.

Adult↗
PubMed1976

Resident evaluation - is our method effective?

In an earlier paper, "Resident Evaluation--Is Your Method Effective?", it was emphasized that the objectives for the residency program in Radiology should be clearly delineated and used to judge the performance of the resident in all stages of the training program. After having had approximately three years' experience in the use of the procedures outlined in the original paper, we are recommending some changes and modifications. The purpose of the evaluation is to provide clear and detailed evidence of the performance of the resident over the period of his training program. As outlined in the previous paper, the basic principles -- learning is a very individual matter, learning depends on the motivation of the individual, and learning depends on the satisfaction in the learning task--remain unaltered. Changes have been made in the design, execution and details of evaluation. The final sucess of any training program will necessarily be measured by the degree to which the residents attain the outlined objectives of the program and the degree to which the graduates of the program are accepted into the specialty by the accrediting bodies.

Canada↗
PubMed1975

Lorazepam as a premedicant for day-case surgery: an assessment.

The sedative effect of 2 mg of lorazepam was assessed in eleven patients undergoing minor "day case" surgery and the results compared with a control group of eleven patients receiving a placebo. Sedation was assessed by a scoring method and quantified in terms of change in plasma cortisol levels. The results indicate that 2 mg of oral lorazepam produces good sedation (superior to nitrazepam in terms of plasma cortisol reduction) and has a postoperative anti-emetic effect but its prolonged duration of action makes it unsuitable for patients returning home within 8 hours of premedication.

Adult↗