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Biomedical subjects

C H Pierce

Publications and source records attributed to C H Pierce.

33 records · Page 2Linked to original sources
PubMed1978

Protein and fat utilization in shock.

A previous study demonstrated that in the dog, shock, regardless of its etiology, resulted in increased oxidative utilization of substrates which form lactate and pyruvate as intermediary metabolites. The study implied a concomitant decrease in free fatty acid oxidation, as the oxidative pathway of the latter does not involve the lactate-pyruvate step. To test this hypothesis, free fatty acid metabolism was investigated by infusing carbon-14 labelled fatty acid in 12 normal dogs, in nine animals in shock due to controlled cardiac tamponade, and in six animals with endotoxin shock. The shock state was characterized by significant (p less than 0.05) decrease both in arterial fatty acid concentration and in free fatty acid turnover. In addition, both the rate of free fatty acid oxidation and the percentage of the total CO2 derived from free fatty acid oxidation were significantly (p less than 0.05) diminished. In contrast, urea production rates were higher in shock, and the calculated maximum contribution of protein oxidation to total CO2 production rose from 23% in the control animals to 50% in the test groups.

Animals↗
PubMed1976

Lactate metabolism in the dog during shock from hemorrhage, cardiac tamponade or endotoxin.

The elevated arterial lactate concentration in shock was investigated by measuring lactate production and clearance rate using a constant infusion of 14C-labeled lactate. In addition, the pathways of lactate metabolism were characterized by determining the percentage of lactate under-going oxidation and the percentage of the total carbon dioxide production which was derived from lactate. These measurements were performed on 16 normal dogs and on 23 dogs in a state of shock. Shock was induced by hemorrhage in ten, by controlled cardiac tamponade in seven and by endotoxin injection in six. In all of the dogs in a state of shock, there was a statistically significant increase in both the arterial lactate concentration and lactate turnover, while the lactate clearance decreased significantly. The percentage of the arterial lactate which underwent oxidation remained normal. The percentage of the total carbon dioxide production which was derived from lactate increased significantly, p less than 0.05, from 4.7 per cent in the normal dogs to 22.7 per cent in the dogs in a state of shock. Since both oxygen uptake and carbon dioxide production remain unchanged in shock, these data are consistent with an increased metabolism of substrates which from pyruvate and lactate as intermediary metabolites, that is, carbohydrates and certain amino acids, with a concomitant decrease in the metabolism of substrates which do not form pyruvate, that is, free fatty acids. In both the normal and shocked dogs, the arterial lactate concentration rose as the lactate production rate increased. Therefore, the elevated arterial lactate in shock was due to an increase in the lactate production and not to a lack of oxygen.

Animals↗
PubMed1974

Improving job performance of Neighborhood Youth Corps aides in an urban recreation program.

In most federal job training and employment programs, trainees' pay is not contingent on job performance, but upon physical presence. This study sought to increase the job performance of seven Neighborhood Youth Corps workers being paid an hourly wage for serving as aides in an urban recreation program. When thorough job descriptions and threatened termination of employment were insufficient to maintain adequate job performance, an attempt was made to make the hourly wage (required by the Neighborhood Youth Corps program) more contingent on job performance. When the number of hours credited the workers on their payroll sheets was proportional to their rating on a simple checklist of job performance, rather than to the number of hours they were present, their job performance was maintained at near-perfect levels. Although this simple semantic shift in emphasis-from "hours worked" to "hours worked"-was still interpreted as meeting the Neighborhood Youth Corps requirements for hourly pay, its behavioral effects were substantial. This simple procedure might be used in other training programs handicapped by hourly wage requirements.

Adolescent↗
PubMed1974

Recreation as a reinforcer: increasing membership and decreasing disruptions in an urban recreation centre.

It is presumed that recreation activities have a variety of functions for people, from tension reduction to citizenship development; however, a recreation activity's most empirically obvious function is as a reinforcer. This study demonstrates how two recurrent problems of urban recreation programs-recruitment of members and reduction of disruptive behaviors within the program-can be handled simply by contingently adjusting the amount of time the recreation activities are available. When extra time in the recreation center was provided to those youths who brought new members, dramatic increases in membership were achieved. On the other hand, when the closing time for each evening's recreation program was publicly moved forward by a few minutes for each offense, disruptive behaviors were nearly eliminated. Recreation used as a reinforcer can thus improve the basic operation of a recreation center and might similarly enhance other presumed and desired functions of recreation.

Journal Article↗
PubMed1972

Effects of different delay of reinforcement procedures on variable-interval responding.

Two experiments studied responding in the rat when the first bar press after a variable period of time produced a cue light that remained on for either 10, 30, or 100 sec and terminated with the delivery of food. In Experiment I, response rate decreased and time to the first response after reinforcement increased as the delay of reinforcement increased. Similar results were obtained whether the delay consisted of retracting the lever during the delay, a fixed delay with no scheduled consequence for responding, or every response during the delay restarted the delay interval. In Experiment II, fixed-delay and fixed-interval schedules of the same duration during the delay period had no differential effect on either response rate or time to the first response after reinforcement, but differentially controlled responding during the delay periods.

Journal Article↗