David Cardus

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). As estimated in this study, the amount of bone mass constituted a higher percentage of the gross BW. This suggests that, although SCI patients lose calcium in the early stages of the disease, the loss of weight that follows SCI is principally due to the loss of W, F, and P.

An analysis of errors in a technique for the combined use of multiple radioisotopes.

The ability to maintain a small error was uncertain in a technique which involved the simultaneous use of five radioisotopes. A systematic in vitro investigation was undertaken to assess the technical errors and the total error in the technique. Technical errors in counting activity, pipetting samples, and measuring tracer volumes were determined separately. Sixty-eight determinations of five known volumes of water were made to evaluate the total error. The results of the in vitro volume estimates were submitted to statistical analysis. Four questions were asked. (1) Was there a significant difference between the estimated volumes obtained by the five isotopes and the known volumes? (2) Was there a significant difference between the estimated volume obtained with each isotope and that obtained with the other isotopes? (3) Were all the volume levels studied estimated with the same degree of accuracy by either of the five isotopes? (4) Can changes in volume of ten percent, at levels of 2 1. and 10 1., be estimated with sufficient accuracy to enable quantitative statements to be made about estimates of equivalent changes in physiological volumes? The technical errors in the technique were small resulting in an average total error of 0·85 percent between the known and estimated volumes using pooled data. Either isotope was found to be equally as accurate as the other isotopes in estimating any of the volumes studied. This in vitro assessment of errors indicates the techniques to be sufficiently accurate and reproducible to be utilized in a quantitative estimate of changes in physiological volumes.

TRITIUM OXIDE MOVEMENT IN BODY WATER OF HEALTHY AND PARALYTIC MEN

Abstract A comparison between male patients with muscular paralysis and healthy male subjects of similar age was made. The parameters compared were: body weight (BW), total body water (TBW), and the rate constants of tritium oxide (HTO) loss, 1) from plasma water, 2) through urination, 3) through other routes such as perspiration, respiration, and defecation. Similarities between patients and healthy subjects were found in: 1) the volume of water per unit of body mass, 2) the rate of HTO turnover in plasma water, 3) the volume of plasma water turnover per hour. The most notable dissimilarity was observed in the rate of plasma water HTO turnover. The plasma water HTO turnover changed with time in healthy subjects, whereas in patients with paralysis it remained essentially the same. Also, the fraction of HTO loss and water loss through urination was higher in patients than in healthy subjects. Evidence was found which supports the hypothesis that there is an eflux and influx of high tritium concentration in and out of the plasma water of most healthy subjects. These fluxes are either absent or occur less frequently in patients with muscular paralysis.