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Biomedical subjects

A Buxton

Publications and source records attributed to A Buxton.

12 recordsLinked to original sources
PubMed1994

Cholinergic agents and delay-dependent performance in the rat.

We tested cholinergic agents in delayed matching and nonmatching to position. Each task had a delay between the presentation of information and the chance to act on it later. We used a titrating procedure, new to experiments with rats, to determine the delay. Linopirdine (0.1 mg/kg), which releases acetylcholine, and physostigmine (0.1 mg/kg), a cholinesterase inhibitor, ameliorated the impairment of accuracy produced by scopolamine hydrobromide (0.1 mg/kg). In some cases, scopolamine hydrobromide decreased the number of trials, but physostigmine and linopirdine did not ameliorate that impairment. Both the muscarinic receptor antagonist, scopolamine hydrobromide (0.1 and 0.3 mg/kg), and its peripherally acting analog, scopolamine methylbromide (0.1 and 0.3 mg/kg), decreased accuracy. The impairment produced by scopolamine methylbromide suggests that the deficit produced by muscarinic receptor antagonism may have both a central and peripheral component. At the highest dose, scopolamine hydrobromide decreased the number of trials completed. Thus, some of the effects of scopolamine hydrobromide involve nonmnemonic performance factors. The performance deficits produced by scopolamine hydrobromide suggest that it may be necessary to qualify drug effects in terms of their action on both memorial and nonmemorial aspects of performance.

Acetylcholine↗
PubMed1992

Multidimensional aspects of drinking in the rat.

In 60-min test sessions, thirsty rats licked an empty metal spout for 0.2-milliliter shots of water delivered audibly to a neighboring spout that remained accessible after the first delivery. As the instrumental empty-lick requirement increased they drank less water, in accordance with the demand law, but made the same number of licks at the water delivery spout. In terms of water licks/milliliter they, therefore, licked less efficiently at higher behavioral prices, opposite to the relation obtained when rats respond for licks at a spout full of water. Given a continuous supply of free water they licked more efficiently, and licks varied in strict proportion to the amount drunk. Yoked controls with no instrumental requirement drank the same amount and made the same number of water licks as their price-paying experimental partners. Thus, intermittent delivery of a small amount of water induced rats to lick the delivery spout at a relatively high average rate that was unaffected by the behavioral price of the delivery or the interdelivery interval. Opposite efficiency effects suggest that external constraint on any dimension of drinking will affect that dimension more than any other left unconstrained.

Animals↗
PubMed1990

Efficiency and persistence of licking in rats.

Thirsty rats tested in 60-min sessions licked an empty spout for access to a water spout. We raised the behavioral price of the water lick by requiring more licks at the empty spout per lick at the water spout. At relatively high prices the rats made relatively few water licks but licked more efficiently, getting more water per lick. Controls showed that the rise in efficiency with price was not attributable to two variables previously confounded with price: the total number of water licks, and the temporal pattern of access. At a higher price the rats also licked more persistently, making more extra water licks before the shutter could occlude the spout. However, yoked controls showed that the greater persistence resulted not from price, but from the relatively stringent pattern of access that accompanied the higher price. Extra water licks diminished as the session progressed, apparently from satiety, not fatigue. The results have implications for behavioral ecology, behavioral economics, motivation, and the methodology of reward.

Animals↗
PubMed1986

Does sucrose damage kidneys?

There is evidence to suggest that sucrose ingestion can cause renal parenchymal changes as well as increasing the urinary saturation index for calcium oxalate. Ten stone formers and 10 normal subjects received 250 gm of sucrose daily over a period of 7 days. Observations on the risk factors for calcium stone formation and urinary N-acetyl-B-glucosaminidase (NAG), a marker of renal tubular cell damage, were made. Oxalate excretion increased. Urinary calcium levels were unchanged but the pattern of response was different between the two groups, as with magnesium and phosphate. NAG was spontaneously higher in the patient group and increased significantly after sucrose ingestion in both groups.

Acetylglucosaminidase↗
PubMed1985

Self-management of nutrition.

Eleven overweight subjects received a behavioral treatment program for weight loss and a nutritional self-management program during a 10-week treatment period. The nutritional self-management program was evaluated using a multiple-baseline across-groups design. The results indicated that caloric restriction without the nutritional self-management program did not result in the consumption of a well-balanced diet. Introduction of the nutritional self-management program led to improvement of nutritional consumption across six food groups. Self-control of caloric intake within certain food groups, i.e., fruit and vegetable, was better than for others. These findings are discussed in terms of the methodological difficulties involved in managing nutrition and the significance of nutritional self-management for health problems other than obesity.

Behavior Therapy↗
PubMed1982

Dietary management of urinary risk factors in renal stone formers.

Three hundred and ninety-two stone formers were investigated to exclude systemic disorders and to define the presence of haematological and urinary abnormality commonly associated with stone disease. Increased urinary excretion of calcium, oxalate or uric acid was found in 40% and there was more than one abnormality in 16% of the patients. The dietary habit of stone formers did not differ significantly from that of control subjects. Dietary advice to increase the consumption of fibre and reduce the consumption of sugar, refined carbohydrates and animal protein produced a significant reduction in the urinary excretion of calcium, oxalate and uric acid. We consider that reduction of the nutrient density of the diet by this means is the first line of management of idiopathic stone formers.

Adolescent↗
PubMed1980

Refractory ergonovine-induced coronary vasospasm: importance of intracoronary nitroglycerin.

Recent experience has suggested that the ergonovine maleate test is a safe procedure for the diagnosis of variant angina pectoris, because ergonovine-induced coronary vasospasm has generally been reversible by sublingual nitroglycerin. This report describes five cases of ergonovine-induced coronary vasospasm that were refractory to sublingual nitroglycerin. Four of these patients had cardiac arrest. In two patients the vasospasm was responsive to intracoronary nitroglycerin administration. Three patients died as a reuslt of the test. The two survivors differed from the nonsurvivors in the total dose or ergonovine given (0.1 and 0.15 mg versus 0.17, 0.3 and 0.3 mg, respectively) and in the method of administration of ergonovine. The survivors were given serial doses of 0.05 mg each whereas the three nonsurvivors received either larger initial doses (0.1 followed by 0.07 mg) or progressive incremental doses (0.05, 0.1 and 0.15 mg serially). Sublingual nitroglycerin, given to all five patients, and intravenous nitroglycerin, given to three of the five, were ineffective in reversing vasospasm. Intracoronary nitroglycerin favorably altered the course of the survivors. Thus, the ergonovine maleate test is not benign and may cause severe coronary vasospasm that is unresponsive to sublingual and intravenous nitroglycerin, but may be reversed by intracoronary nitroglycerin.

Administration, Oral↗
PubMed1978

Acinetobacter calcoaceticus outbreak associated with peritoneal dialysis.

Investigation of an outbreak of contamination of dialysis drainage fluid with Acinetobacter calcoaceticus var. anitratus identified a previously unrecognized source for dialysis associated infections. Over a 4-month period, 25 peritoneal dialysis treatments were administered to 13 hospital patients. Of the 25 treatments for which culture results were available, 14 were associated with dialysis drainage fluid cultures positive for A. calcoaceticus. A water bath used to warm bottles of peritoneal dialysate before use was the reservoir for the bacteria, and investigation showed in vitro that bath water could contaminate the dialysate. It appears likely that the dialysate became contaminated when the prong of the fluid administration set was inserted through the rubber bung on the dialysate bottles. This outbreak illustrates the potential importance of environmental reservoirs in infections complicating peritoneal dialysis.

Acinetobacter↗