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Biomedical subjects

C Perry

Publications and source records attributed to C Perry.

At least 109 records · Page 6Linked to original sources
PubMed1985

Pressure-time product, flow, and oxygen cost of resistive breathing in humans.

We examined the relationship between the pressure-time product (Pdt) of the inspiratory muscles and the O2 cost of breathing (VO2 resp) in five normal subjects breathing through an external inspiratory resistance with a tidal volume of 800 ml at a constant end-expiratory lung volume [functional residual capacity, (FRC)]. Each subject performed 30-40 runs, each of approximately 30 breaths, with inspiratory flow rates ranging from 0.26 +/- 0.01 to 0.89 +/- 0.04 l/s (means +/- SE) and inspiratory mouth pressures ranging from 10 +/- 1 to 68 +/- 4% of the maximum inspiratory pressure at FRC. In all subjects VO2 resp was linearly related to Pdt when mean inspiratory flow (VI) was constant, but the slope of this relationship increased with increasing VI. Therefore, Pdt is an accurate index of VO2 resp only when VI is constant. There was a linear relationship between the VO2 resp and the work rate across the external resistance (W) for all runs in each subject over the range of W 10 +/- 1 to 137 +/- 21 J/min. Thus, at a constant tidal volume the VO2 resp was related to the mean inspiratory pressure, independent of flow or inspiratory duration. If the VO2 resp were determined mainly during inspiration, then for a given rate of external work or O2 consumption, VI would be inversely related to mean inspiratory pressure. Efficiency (E) was 2.1 +/- 0.2% and constant over a large range of VI, pressure, work rate, or resistance and was not altered by the presence of a potentially fatiguing load. The constant E over such a wide range of conditions implies a complex integration of the recruitment, mechanical function, and energy consumption of the muscles utilized in breathing.

Adult↗
PubMed1984

Properties of electroretinographic intensity-response functions in retinitis pigmentosa.

Dark-adapted electroretinogram (ERG) b-wave amplitudes and implicit times were recorded as a function of stimulus luminance for 15 retinitis pigmentosa (RP) patients and 15 normal subjects. B-wave amplitude as a function of log stimulus luminance was fit by non-linear regression with the Naka-Rushton equation, which has 3 independent parameters: The maximum response (Rmax), slope (n) and half-saturation constant (K). B-wave implicit-time as a function of log stimulus luminance was fit by linear regression. Compared to normal, the RP Rmax values were markedly reduced, suggesting response compression; the RP K values were elevated by an average of 0.76 log unit, suggesting relatively small losses in retinal sensitivity. There was no correspondence between Rmax and visual field area for the RP patients (coefficient of correlation = -0.02). All but 2 of the 15 RP patients had normal or shallower-than-normal implicit-time intensity-response functions, indicating that over most of the dynamic range of the ERG, the implicit-times were either normal or faster-than-normal. These results are discussed in terms of possible RP disease mechanisms.

Adolescent↗
PubMed1984

Patient diagnostic, behavioral and demographic variables associated with changes in civil commitment procedures.

Examined diagnostic and demographic characteristics of six groups of voluntary and committed patients (N = 300) over a 3-year period in order to assess the impact of a change in civil commitment procedures in the state of Missouri. Committed and voluntary patients differed on the basis of several demographic and behavioral variables, including diagnosis, employment status, and instances of serious physical harm recorded on admission. No differences were found between patients committed under the old law (which stipulated that the presence of "mental illness" was a sufficient criterion) and patients committed under the new law (which requires the presence of serious physical harm as an essential criterion). These findings were interpreted to suggest that, in at least some settings, clinicians were restricting commitment to cases that gave evidence of physical harm prior to the enactment of new legislation.

Adult↗
PubMed1984

New lessons favoring physicians' support of clinical trials.

The publications of the Hypertension Detection and Follow-up Program and the Multiple Risk Factor Intervention Trial have produced different opinions concerning the therapeutic implications of their results. However, they provide new lessons concerning the design of clinical trials and the ethical implications of this research. Their experiences clearly illustrate the scientific requirements for controlled clinical trials and clarify the ethical validity of future investigations for medical researchers and the medical profession.

Attitude of Health Personnel↗
PubMed1983

Hypnotically created memory among highly hypnotizable subjects.

A pseudomemory of having been awakened by some loud noises during a night of the previous week was suggested to 27 highly hypnotizable subjects during hypnosis. Posthypnotically, 13 of them stated that the suggested event had actually occurred. This finding has implications for the investigative use of hypnosis in a legal context.

Adult↗
PubMed1983

Physicochemical characterization of large unilamellar phospholipid vesicles prepared by reverse-phase evaporation.

Properties of large unilamellar vesicles (LUV), composed of phosphatidylcholine and prepared by reverse-phase evaporation and subsequent extrusion through Unipore polycarbonate membranes, have been investigated and compared with those of small unilamellar vesicles (SUV) and of multilamellar vesicles (MLV). The unilamellar nature of the LUV is shown by 1H-NMR using Pr3+ as a shift reagent. The gel to liquid-crystalline phase transition of LUV composed of dipalmitoylphosphatidylcholine (DPPC) monitored by differential scanning calorimetry, fluorescence polarization of diphenylhexatriene and 90 degrees light scattering, occurs at a slight lower temperature (40.8 degrees C) than that of MLV (42 degrees C) and is broadened by about 50%. The phase transition of SUV is shifted to considerably lower temperatures (mid-point, 38 degrees C) and extends over a wide temperature range. In LUV a well-defined pretransition is not observed. The permeability of LUV (DPPC) monitored by leakage of carboxyfluorescein, increases sharply at the phase transition temperature, and the extent of release is greater than that from MLV. Leakage from SUV occurs in a wide temperature range. Freeze-fracture electron microscopy of LUV (DPPC) reveals vesicles of 0.1-0.2 micron diameter with mostly smooth fracture faces. At temperatures below the phase transition, the larger vesicles in the population have angled faces, as do extruded MLV. A banded pattern, seen in MLV at temperatures between the pretransition and the main transition, is not observed in the smaller LUV, although the larger vesicles reveal a dimpled appearance.

Animals↗
PubMed1983

"Hidden observer" phenomena in hypnosis: an experimental creation?

Spanos and Hewitt (1980) have recently argued, on the basis of an experiment they report, that Hilgard's "hidden observer" phenomenon is pure laboratory artifact. This report reviews their claim and concludes on the following grounds that their experiment does not warrant so sweeping a conclusion: (a) Spanos and Hewitt have posed the issue as fact versus fiction and do not appear to be aware of a third alternative, namely, that the hidden observer effect is a phenomenon encountered in hypnosis that may be influenced both by demand characteristics and by the social-psychological context. (b) They appear to obtain the effect 100% of the time, unlike Hilgard, who has emphasized the phenomenon's differential incidence. (c) In contrast to Hilgard, who furnishes abundant verbal reports of his subjects' phenomenal experience as buttressing evidence for the "genuineness" of the effect in subjects who report having it, Spanos and Hewitt do not. (d) Two major procedural aspects of their experiment are discussed. Either or both may have inadvertently influenced the outcome of their experiment in the direction of their hypothesis that the responses of subjects are entirely the product of experimenter-induced expectations.

Awareness↗
PubMed1982

An NMR study of 13C-enriched galactose attached to the single carbohydrate chain of hen ovalbumin. Motions of the carbohydrates of glycoproteins.

In order to facilitate the study of motions of the carbohydrate moiety of glycoproteins, a method of enzymatically attaching uniformly 13C-enriched galactopyranose ([U-13C]galactose) onto the nonreducing end of the carbohydrate chain has been developed. Specifically, [U-13C]glucose (20% 13C) was converted through a sequence of four enzymatic steps to [U-13C]UDP-galactose which was then attached, via a beta-1,4 glycosidic bond, to a nonreducing terminal N-acetylglucosamine of hen ovalbumin using the enzyme bovine galactosyltransferase. The overall reaction was followed using 31P and 13C NMR. 13C NMR spectra of the modified ovalbumin show six well resolved resonances arising from the six carbons of the attached [U-13C]galactose. Values of the spin-lattice relaxation time, the line width, the 13C (1H) nuclear Overhauser effect, and the intensity ratio, a measure of the off-resonance rotating frame spin-lattice relaxation time, were obtained for the individual carbons of the [U13-C]galactose as well as other carbon resonances of the protein. Relaxation data for the protein alpha-carbon and aromatic methine carbon resonances could be fit to theoretical values by assuming a correlation time of 25 ns for overall isotropic motion of the glycoprotein. Relaxation data for the anomeric carbon of the attached [U-13C]galactose could only be fit by assuming an additional correlation time between 40 and 80 ps for free internal motion, subject to the constraint that its carbon-proton bond vector makes an angle of about 30 degrees with an effective axis of rotation.

Animals↗