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Biomedical subjects

D G Ellis

Publications and source records attributed to D G Ellis.

30 records · Page 2Linked to original sources
PubMed1983

A computerized mass spectrometer and flowmeter system for respiratory gas measurements.

Instrumentation systems for breath-to-breath analysis of respiratory gas exchange have been faulted by phase lags between various flow and composition signals and by difficulties in gathering and processing large amounts of data. The system described here represents an attempt to overcome these problems. Phase delays have been minimized by using a direct, piezoelectrically operated mass spectrometer inlet rather than an inlet capillary, by locating the mass spectrometer inlet and flow sensors in the same plane, and by incorporating design features which enhance the mass spectrometer response. Convenience in system operation and data analysis has been enhanced by integrating a computer into the system design so that the computer performs on-line data analysis and control functions and provides the primary interface between the experimenter and the instruments. Miniaturization of the instruments permits close coupling to an exercising subject.

Calibration↗
PubMed1981

Voiding abnormalities in children: methods of evaluation and results of treatment.

Recent advances in technology have fueled interest in the field of urodynamics and have made possible accurate diagnosis of voiding abnormalities in children. A thorough understanding of the underlying physiology and institution of the appropriate pharmacologic agents and/or teaching techniques results in correction of the underlying problems in 90% of the cases. Symptoms, techniques of diagnosis, therapeutic regimens, and results of therapy are presented.

Adolescent↗
PubMed1980

Lightweight remotely actuated switching valve for rebreathing exercise studies.

A new type of switching valve used in rebreathing studies for estimating cardiac output is described. This valve employs a unique deformable elastic element, actuated by low-pressure compressed air, to effect switching. The capability for remote operation (via a compressed air line) and the light weight of the valve (110 g) make the valve especially well suited to exercise stress testing studies. Two valves of this type have been satisfactorily used in graded exercise stress tests in a clinical setting for over 2 yr.

Carbon Dioxide↗
PubMed1976

New respiratory gas valve support for graded exercise studies.

We describe a new support structure for respiratory gas valves for use in exercise studies. Use of this structure largely avoids problems of large inertial reactions and feelings of confinement on the part of the subject which have characterized previous systems. The support mechanism consists of a spring-reacted, pivoted boom carried on the end of a counterbalanced swinging beam. This device was designed for use on an adjustable slope motor-driven treadmill, but may be adapted to a variety of other experimental arrangements.

Humans↗
PubMed1976

Dose-response effects of anti-inflammatory steroid injections on mechanical properties of rat tail tendons.

It has been suggested that glucocorticoid drug therapy or usage may be a contributing factor in the occurrence of tendon ruptures among athletes. Our earlier findings (7) did not support this position but may have been dependent on the small quantity of drug injected. We subsequently tested selected biomechanical properties of healthy, non-traumatized tail tendons from sixty 90-day-old Sprague-Dawley rats previously injected weekly for six weeks with 0.1 ml saline (controls) or low (0.03 mg/0.1 ml), medium (0.30 mg/0.1 ml) or high doses (0.60 mg/0.1 ml) of betamethasone. Results indicate the biological effectiveness of the medium and high dose treatments through reductions in body and adrenal weights, but we found no statistically significant change in dry tendon weight, yield load or relative yield load, although there was a suggestive trend toward lessened dry tendon weights and greater relative yield loads. The hypothesis that repeated local injections of an anti-inflammatory steroid deleteriously effects mechanical properties of healthy, non-traumatized rat tendons is not supported by our data, even considering that some dosages were 10 to 20 times greater than recommended therapeutic quantities for humans.

Adrenal Glands↗
PubMedDate not supplied

A multi-state survey of videotaping practices for major trauma resuscitations.

The objective of this study was to determine the prevalence and problems, both perceived and actual, associated with videotaping major trauma resuscitations. A cross-sectional two-part survey of trauma centers was conducted. Part 1 determined demographic information and videotaping status. Part 2 asked trauma centers that were not doing videotaping (NVTCs) about their plans, past experience, and perceived problems. Videotaping trauma centers (VTCs) were asked about mechanics, responsibility, utilization, and problems. A total of 221 centers were surveyed; 20% VTCs, 70% NVTCs, and 10% NVTCs that had videotaped in the past (PVTC). Among VTCs, 53% reported problems with videotaping including lack of personnel (40%) and time (40%) to administer the program. Videotaping, however, was found to be an effective quality improvement tool in 95% of the VTCs. Of the NVTCs, 70% perceived problems with implementing a videotaping program; these included medicolegal (34%) and patient confidentiality (22%) concerns. Of the PVTCs, 90% stated that they had problems with videotaping including lack of staff support (33%) and lack of personnel to assist with the program (24%). In conclusion, staff participation and adequate personnel outweigh medicolegal concerns as actual videotaping problems. Videotaping is perceived to be an effective performance improvement tool.

Cross-Sectional Studies↗
PubMedDate not supplied

A noninvasive method for recording the electrical activity of the human uterus in vivo.

Development of an electrohysterograph (EHG) for recording the electrical activity of the uterus in vivo has been blocked for 60 years by problems with artifacts and extraneous/reactive electrical activity. This study reevaluates a method of cervical recording that does not appear to have these limitations. A set of cervical electrode cups was used to record uterine activity of 33 normal subjects and patients who had dysmenorrhea, endometriosis, or chronic pelvic pain. The electrode cups were atraumatic, able to be fitted to all subjects, and showed exceptional positional stability. Unipolar and bipolar recordings from the cervix showed the same infrequent spikes and spike bursts reported from other studies along with continuous, mildly irregular, undulating slow-wave activity, which was present throughout the recordings. The frequencies and amplitudes of these slow waves changed in relation to exogenous estrogen, diagnosis, intrauterine catheters, and the intensity of the subject's pain. Spikes and spike bursts were common only during menses and at midcycle. The cervical electrode cups proved easy to use and were well accepted by the subjects. The findings indicated that the spikes and slow waves were probably uterine in origin and not artifact or extraneous/reactive activity. There were also direct and indirect indications that the slow waves may represent the ionic propagation of uterine electrophysiologic activity through a network of uterine intercellular ionic channels (gap junctions). The limited but fairly consistent evidence from a number of perspectives indicates that recording spike and slow-wave activity from the cervix is a viable and practical EHG method.

Adult↗