Biomedical subjects
Publications and source records attributed to L C Ward.
A procedure for estimating the rate of turnover of F-actin-bound ADP in vivo is described. A turnover rate of 0.88 h-1 was determined for mouse muscle F-actin. The validity of the method when used to estimate the turnover rate of F-actin per se is discussed in relation to the possible exchange of F-actin-bound ADP.
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The causes and prevention of inadequate isolated organ perfusion are discussed. The consequences of inadequate perfusion are outlined and presented as a rationale for the choice of appropriate tests of viability. The routine application of some tests is advocated and the criteria used in the assessment of the results of such test considered.
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For any task, the eye can respond effectively if there is enough light, if that light is properly distributed, if the appropriate color correction is provided, and if visual contrasts are balanced. Dental offices differ in the types of work performed, the number of people engaged in various tasks, and the types of patients treated. Each office and each room can be planned according to the guidelines herein suggested as long as a rational analysis is applied to the result desired and the tasks being accomplished. The authors suggest that all concerned with office design, the architect, the contractors, and even other illuminating engineers be asked to read this article before integrating their efforts, for the dental office presents some variations not frequently encountered by these people. The need for conservation of our energy sources mandates wise use of all our energy expenditures. There is another resource conservation need that is sometimes overlooked--the effective use of talented people such as the dentist and his staff. The employment of adequate illumination design heeds both demands while giving a rewarding pleasantness and enjoyment of the work environment.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Even when all known factors affecting the determination of nerve conduction velocity are controlled, large individual variations persist. In 40 normal controls, we found that peroneal and sural conduction velocities varied inversely with body height (P less than 0.001). This height effect is not due to temperature differences, and it explains almost 50% of the intersubject variability in conduction velocity. We hypothesize that the height influence reflects abrupt, rather than gradual, tapering of axons distally. This mode of tapering may help explain the decrements in conduction velocity from proximal to distal nerve segments and from upper to lower extremities, which have long been observed in clinical electromyography. Clinical recognition of this height effect is important lest one label as abnormal an individual with mildly slowed peripheral nerve conduction velocity solely related to large stature.
Fluid shifts from intracellular to extracellular water (ICW to ECW) are a feature of sepsis, caused by increased vascular permeability and cell catabolism. Changes in ECW and total body water (TBW) were assessed in a prospective observational study of patients with bacteremia by a bedside technique, and its prognostic impact determined. In 78 hospital patients with fever, the resistance ratio (Rinf/RO) and estimated ECW/TBW ratio from multifrequency bioelectrical impedance analysis, and f1p4m albumin concentration were measured. Rinf/RO and ECW/TBW ratios decreased from day 0 to 2 in patients with significant bacteremia (n = 31), but not in patients with doubtful or negative blood cultures (n = 22 and 25). Increased Rinf/RO at baseline, and further increase of ECW/TBW from day 0 to 2, were associated with lower rate of recovery after 1 week and with higher mortality. Baseline Rinf/RO above the median (0.75) had positive and negative predictive values of 0.31 and 0.95 for death. This prognostic effect was independent of underlying disease and blood culture result in a multivariate model. Hypoalbuminemia at baseline was predictive of outcome, but changes in albumin from day 0 to 2 were unrelated to blood culture results or outcome. In patients with bacteremia, fluid shifts from intracellular to extracellular water occur early, are rapidly reversible by antibiotic treatment but are associated with adverse prognosis. Bioelectrical impedance deserves further study as a tool for bedside monitoring of patients with bacteremia.
To determine the efficacy of Self-Examination Therapy as an adjunct treatment for depressive symptoms in substance abusing patients, 28 adult male volunteers from a substance abuse unit at a VA Medical Center were randomly assigned to either Self-Examination Therapy or a Current Events comparison group. Analyses indicated that participants in Self-Examination Therapy showed significantly greater improvement in depressive symptoms and overall psychopathology than participants in the Current Events comparison group. These results suggest that Self-Examination Therapy is a viable adjunct treatment for substance abusers, particularly those with depressive symptoms.
We analyzed National Registry data from 575 patients with subacute sclerosing panencephalitis (SSPE) in the United States to assess changes in patient characteristics and SSPE epidemiology. Racial proportions have changed in recent years with an increasing number of Hispanic patients reported in relation to a constant black:white ratio; however, the male:female ratio of approximately 2:1 has remained. The most striking feature of the data is the rapid decline in SSPE incidence. Corresponding to this decrease is an increase in the proportion of cases following measles vaccination. There also is a shorter incubation period for SSPE following vaccination than after measles infection.
Bioelectrical impedance analysis (BIA) offers the potential for a simple, portable and relatively inexpensive technique for the in vivo measurement of total body water (TBW). The potential of BIA as a technique of body composition analysis is even greater when one considers that body water can be used as a surrogate measure of lean body mass. However, BIA has not found universal acceptance even with the introduction of multi-frequency BIA (MFBIA) which, potentially, may improve the predictive accuracy of the measurement. There are a number of reasons for this lack of acceptance, although perhaps the major reason is that no single algorithm has been developed which can be applied to all subject groups. This may be due, in part, to the commonly used wrist-to-ankle protocol which is not indicated by the basic theory of bioimpedance, where the body is considered as five interconnecting cylinders. Several workers have suggested the use of segmental BIA measurements to provide a protocol more in keeping with basic theory. However, there are other difficulties associated with the application of BIA, such as effects of hydration and ion status, posture and fluid distribution. A further putative advantage of MFBIA is the independent assessment not only of TBW but also of the extracellular fluid volume (ECW), hence heralding the possibility of being able to assess the fluid distribution between these compartments. Results of studies in this area have been, to date, mixed. Whereas strong relationships of impedance values at low frequencies with ECW, and at high frequencies with TBW, have been reported, changes in impedance are not always well correlated with changes in the size of the fluid compartments (assessed by alternative and more direct means) in pathological conditions. Furthermore, the theoretical advantages of Cole-Cole modelling over selected frequency prediction have not always been apparent. This review will consider the principles, methodology and applications of BIA. The principles and methodology will be considered in relation to the basic theory of BIA and difficulties experienced in its application. The relative merits of single and multiple frequency BIA will be addressed, with particular attention to the latter's role in the assessment of compartmental fluid volumes.
The effect of skin temperature and hydration status has been suggested by some researchers as a common cause of variation in bioimpedance measurements of the body. This paper details a simple method of measuring the transverse impedance of the skin. The measured resistance and reactance was found to decrease by 35% and 18% for an increase of 20 degrees C. Similarly a decrease in resistance and reactance of 20% and 25% respectively was detected after hydration of the skin. However, the changes in skin temperature and hydration were found to have no significant effect on the whole body bioimpedance measurements using the standard tetra-polar electrode technique.