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R D Phillips

Publications and source records attributed to R D Phillips.

At least 73 records · Page 4Linked to original sources
PubMed1980

A comparison of two nonlinear models for describing intake-response relationships in higher organisms.

Comparison of two nonlinear models for describing intake-response relationships in higher organisms is presented. The first model is based on the assumption that growth processes obey saturation kinetics phenomena while the second model is based on the assumption that the absolute size of the body is the factor which determines the rate of the growth process. Comparison of the two models is illustrated by considering a typical experiment for the evaluation of intake-response relationships.

Animals↗
PubMed1980

Estimators of body nitrogen in growing rats fed varying levels and qualities of protein.

The relationships between total body nitrogen and body weight, carcass water and carcass [body minus gastrointestinal (GI) tract] nitrogen were investigated with Sprague-Dawley rats fed diets containing casein, peanut flour or wheat gluten as protein sources. Twelve diets containing 2-31% of each protein fed to groups of six (12 for protein-free diet) weanling rats for 4 weeks. The animals were killed by sodium pentobarbital injection and weighed. GI tracts were removed and washed free of their contents. Carcass water was determined by oven drying; carcass and GI tract nitrogen were determined by Kjeldahl analysis. Linear regression equations for each relationship and protein closely fit the data (r2 greater than 0.9). In each relationship the equations for casein and peanut protein were not significantly different (P less than 0.05), but both were different from the equation for gluten. Despite high r2 values, plots of deviations from regression showed a distinct pattern in several cases. Quadratic equations relating body nitrogen to the other parameters gave improved fit of the data in most instances. Quadratic equations for a given relationship were not significantly different for the three proteins. Net protein utilization (NPU) values based on body nitrogen estimated by linear equations were significantly different from those based on determined values in several cases. When quadratic estimating equations were used, the values were different only in one case.

Animals↗
PubMed1976

Automated rodent respiratory monitor and histogram computer--a preliminary report.

The system described in this paper was designed to monitor total inhaled volume (V), tidal volume (VT), and respiratory frequency (f) of Fisher rats before, during, and after exposure to cigarette smoke. The systems consists of three major subsystems: plethysmograph, analog signal conditioner, and histogram computer. The volume type whole body plethysmograph incorporates a rubber nose seal. Tidal flow rate (V) from the tube, measured by a pneumotachometer, is integrated by the signal conditioning system to obtain VT and V. Both V and V are displayed on a strip chart recorder. A rat will often exhibit considerable sniffing, especially in the presence of cigarette smoke. Consequently, average tidal volume (VT) and average respiratory frequency (f) are not accurate measurements of typical VT and f. Sensitivity of the system to changes in typical VT and f is important snce the system will be used to evaluate the effects of subtle differences in types of experimental cigarettes. A microprocessor was used in conjunction with a cathode ray tube to compute and display both the VT and respiratory period (T = 1/f) as histograms. From the histograms the most common (typical) VT (mode of the histogram) and the most common T can be easily observed and recorded. The histogram computer also calculates and digitally displays VT and f.

Analog-Digital Conversion↗
PubMed1975

Thermoregulatory, metabolic, and cardiovascular response of rats to microwaves.

This study was undertaken to determine the effects of 2,450-MHz microwave irradiation on thermoregulation, metabolism, and cardiovascular function of rats. Young adult male animals (430 g) were exposed for 30 min to 2,450-MHz microwaves in a cavity at absorbed dose rates of 0, 4.5, 6.5, or 11.1 mW/G. For animals of the size used in this study, these dose rates represent absorption of energy at the rate of 27.7, 40.1, and 68.2 cal/min, respectively. For a period of 5 h following exposure, measurements were made of colonic temperature, skin temperature, oxygen consumption, carbon dioxide production, respiratory quotient, and heart rate. Rats that received 27.7 cal/min for 30 min exhibited an initial transient increase in colonic and skin temperatures but no alterations in other functions. The group irradiated at 40.1 cal/min had greater elevations in colonic and skin temperatures immediately after exposure, followed by overcompensation and lower than normal colonic temperatures for about 3 h. The metabolic rate was depressed in this group for 3 h. Bradycardia developed within 20 min after exposure and persisted for about 3 h. The group of rats that received 68.2 cal/min for 30 min had responses similar to those of the 40.1 cal/min group, but the changes were more severe and lasted longer. In addition, a number of transient abnormalities were noted in the ECG tracings of rats that had received the highest dose, including irregular rhythms and incomplete heart block. The physiological changes observed in this study can be attributed to the heating induced by irradiation.

Animals↗