Cardiovascular effects of a sustained -Gz force in the horizontal position.

Introduction: The purpose of this investigation was to study the effect of a sustained -Gz force applied in the horizontal position on the cardiovascular system and the distribution of body fluids.

Methods: The study was conducted on four men who were submitted to two protocols. The principal difference between the two protocols was that in Protocol A the subjects remained supine, whereas in protocol B the subjects were submitted to a small -Gz force (0.

Electrical impedance measurements in the arm and the leg during a thirty day bed rest study.

The need to detect, follow and understand the effects of gravity on body fluid distribution is a constant stimulus to the quest for new techniques in this area of research. One of these techniques is electrical bioimpedance spectroscopy (BIS). Although not new, this is a technique whose applications to biomedical research are fairly recent.

Artificial gravity as a countermeasure of physiological deconditioning in space.

The displacement of humans from our planet to space and back to our planet or to another planet necessarily causes the exposure to transitional gravitational forces which create a need for countermeasures of physiological deconditioning. One of the alternative approaches to counteracting physiological deconditioning is the simulation of a gravitational field. An apparatus named the artificial gravity simulator (AGS) has been designed and constructed.

The cardiovascular response to the AGS.

An instrument, the AGS (artificial gravity simulator), has been built to produce artificial gravity. This paper reports preliminary results of experiments on human subjects conducted to study the cardiovascular response to various g-levels and exposure times.

Lipid profiles in spinal cord injury.

Measurement of blood levels of total cholesterol and lipoproteins (HDL and LDL) were conducted on 96 men with spinal cord injury, 46 paraplegics and 50 quadriplegics. All these patients were studied in the stabilized phase of the disease as a follow up to the rehabilitation process. The study was designed to compare results with a normal, able bodied population and to investigate if any abnormal finding could be related to the age at onset of the spinal cord injury, the duration of the disease or the level of the lesion.

Coronary risk in spinal cord injury: assessment following a multivariate approach.

A group of 96 men with spinal cord injury was studied to find out if patients with spinal cord injury were at an increased risk of coronary heart disease. A multivariate approach based on data produced by the Framingham study was used to estimate the probability of developing coronary artery disease within six years. Data obtained from the 96 patients were compared with data obtained from 96 nontrained, able-bodied men matched according to age.

Energy requirements of gamefield exercises designed for wheelchair-bound persons.

This report presents energy requirements of three athletic exercises (power ramp, climber, and chin-ups) in a free-wheeling gamefield developed by the City of Houston for wheelchair-bound persons. Heart rate was monitored by telemetry. Expired gas samples were collected in Douglas bags.

Effects of unilateral, low-frequency, neuromuscular stimulation on superficial circulation in lower extremities of patients with peripheral vascular disease.

The effects of unilateral, low-frequency, neuromuscular stimulation on the circulation in skin of the lower extremities were studied in eight subjects with peripheral vascular disease and eight control subjects with normal peripheral vasculature. Sixty minutes of stimulation (at 2 Hz), of sufficient intensity to produce visible contraction of musculature, was applied through cutaneous electrodes placed over the common peroneal nerve and dorsum of the foot. Systolic and diastolic blood pressure, heart rate, bilateral great-toe photoplethysmographic waveform, and bilateral pedal skin temperature were recorded at 30-min intervals during stimulation and 30 min after stimulation.

Electric impedance measurements in quadriplegia.

Previous experimental studies have shown that measurements of electric impedance of the whole human body relate to body fluid volumes. Measurements using two properly selected current frequencies have been purported to be useful in determining the sizes of extracellular and total body fluids. In this study, measurements of whole body impedance were performed on 20 healthy able-bodied subjects and 20 patients with quadriplegia at the frequencies of 1.

Body composition in spinal cord injury.

A study of body composition was conducted on 45 patients with spinal cord injury (SCI) and 12 able-bodied healthy subjects who served as controls. Body composition was assessed in terms of water (W), fat (F), protein (P), and mineral (M) content. SCI patients exhibited lower absolute amounts of W, F, and P, but no differences in the the amounts of these components when expressed relative (percentage) to gross body weight (BW).

Body sodium and potassium in men with spinal cord injury.

As part of a broad study on the body composition of patients with extensive muscular paralysis, total body water (TBW), extracellular fluid (ECF), exchangeable sodium (Nae), and exchangeable potassium (Ke) were measured in 22 paraplegic and 23 quadriplegic patients. These data were compared with similar measurements obtained on 12 healthy men. Patients with spinal cord injury (SCI) showed a drastic loss of K+, more pronounced in quadriplegic than in paraplegic patients.

Total body water and its distribution in men with spinal cord injury.

During the first months after spinal cord injury there is a drastic loss in body weight. Total body water (TBW) and extracellular water (ECW) were determined in 12 normal healthy men, in 22 paraplegic men and in 23 quadriplegic men. TBW was decreased in both groups of patients, paralleling the loss in body weight, though not totally accounting for the weight loss.

Improved method for densitometry of electrophoretic lipoprotein fraction.

We evaluated a method for the densitometric quantitation of the electrophoretic lipoprotein fractions that sets the limit of integration at the beta-lipoprotein peak maximum. Results were compared with the more conventional method of placing the limit of integration in the valley between the beta- and pre-beta-lipoprotein peaks. The criterion of symmetrical beta-lipoprotein peaks imposed by the method was tested, and manual determination of the beta peak maximum was compared to automatic computer analysis.