From theory to practice: improving the impact of health services research

BACKGROUND: While significant strides have been made in health research, the incorporation of research evidence into healthcare decision-making has been marginal. The purpose of this paper is to provide an overview of how the utility of health services research can be improved through the use of theory. Integrating theory into health services research can improve research methodology and encourage stronger collaboration with decision-makers. DISCUSSION: Recognizing the importance of theory calls for new expectations in the practice of health services research. These include: the formation of interdisciplinary research teams; broadening the training for those who will practice health services research; and supportive organizational conditions that promote collaboration between researchers and decision makers. Further, funding bodies can provide a significant role in guiding and supporting the use of theory in the practice of health services research. SUMMARY: Institutions and researchers should incorporate the use of theory if health services research is to fulfill its potential for improving the delivery of health care

Effects of Prolonged Space Flight on Human Skeletal Muscle Enzyme and Substrate Profiles

Our primary goal was to determine the effects of 6-mo flight on the International Space Station (ISS) on selected anaerobic and aerobic enzymes, and the content of glycogen and lipids in slow and fast fibers of the soleus and gastrocnemius. Following local anesthesia, biopsies were obtained from nine ISS crew members ∼45 days preflight and on landing day (R+0) postflight. We subdivided the crew into those who ran 200 min/wk or more (high treadmill, HT) in-flight from those who ran /wk (low treadmill, LT). In the LT group, there was a loss of lipid in soleus type I fibers, and muscle glycogen significantly increased in soleus fiber types postflight. Soleus cytochrome oxidase (CO) activity was significantly depressed postflight in the type I fiber. This was attributed to the LT group where CO activity was reduced 59%. Otherwise, there was no change in the crew mean for type I or IIa fiber glycolytic or mitochondrial enzyme activities pre- vs. postflight in either muscle. However, two of the three HT subjects (Subjects E and H) showed significant increases in both β-hydroxyacyl-CoA dehydrogenase and citrate synthase in the soleus type I fibers, and Subject E, exhibiting the largest increase in soleus oxidative enzymes, was the only subject to show a significant decrease in glycolytic enzyme activity. It is apparent that crew members performing adequate treadmill running can maintain calf muscle enzymes, which suggests that increased fatigue with weightlessness cannot be directly caused by a decline in muscle enzyme capacity

Effect of a topical beta‐adrenergic receptor antagonist on the dynamics of steady‐state accommodation

The ocular accommodation response to a stationary near target exhibits microfluctuations which arc characterized by two dominant components of activity: a low‐frequency component (LFC: < 0.5 Hz) and a high‐frequency component (HFC: 1.0–2.2 Hz). We have shown recently that there is a significant correlation between the frequency of arterial pulse (AP) and the peak frequency of the HFC. If the mechanisms by which AP induces the HFC are intraocular they are likely to involve both rhythmic variations in choroidal blood flow and intraocular pressure (IOP) pulse: the former inducing changes in ciliary ring diameter from pulsatile blood volume changes in the ciliary body, the latter producing changes in effective lens power following small shifts in lens position or, with each drop in IOP. reduced resistance to inherenl lens substance and capsule elasticity. In addition to its well‐known ocular hypotensive effect, topical instillation of the beta‐ad renergic receptor antagonist timntol maleate has been shown to reduce significantly the magnitude of the IOP pulse, an effect that has been attributed to the vasoconstrictive action of the drug on the choroidal vasculature. Using li modified Canon IR optometcr we report on the effect of 0.5% timolol maleate on the accommodative microfluctuations for a group of 10 emmetropic subjects viewing a target monocularly at a distance of 25 cm. Following a double‐blind protocol against a saline control, timoloi was shown to reduce the rms for both LFCs and HFCs. An experiment to separate local from systemic effects involved four subjects whose treated and untreated eyes were examined to determine the effects of the consensual reduction in IOP: the results on microfluctuations in the untreated eyes were equivocal but the correlation between arterial pulse frequency and location of the peak frequency of HFC was maintained. The results show that factors relating to IOP and vasculature will affect the magnitude of accommodative microfluctuations. Copyright © 1991, Wiley Blackwell. All rights reserve

Prolonged space flight-induced alterations in the structure and function of human skeletal muscle fibres

The primary goal of this study was to determine the effects of prolonged space flight (∼180 days) on the structure and function of slow and fast fibres in human skeletal muscle. Biopsies were obtained from the gastrocnemius and soleus muscles of nine International Space Station crew members ∼45 days pre- and on landing day (R+0) post-flight. The main findings were that prolonged weightlessness produced substantial loss of fibre mass, force and power with the hierarchy of the effects being soleus type I > soleus type II > gastrocnemius type I > gastrocnemius type II. Structurally, the quantitatively most important adaptation was fibre atrophy, which averaged 20% in the soleus type I fibres (98 to 79 μm diameter). Atrophy was the main contributor to the loss of peak force (P0), which for the soleus type I fibre declined 35% from 0.86 to 0.56 mN. The percentage decrease in fibre diameter was correlated with the initial pre-flight fibre size (r = 0.87), inversely with the amount of treadmill running (r = 0.68), and was associated with an increase in thin filament density (r = 0.92). The latter correlated with reduced maximal velocity (V0) (r = −0.51), and is likely to have contributed to the 21 and 18% decline in V0 in the soleus and gastrocnemius type I fibres. Peak power was depressed in all fibre types with the greatest loss (∼55%) in the soleus. An obvious conclusion is that the exercise countermeasures employed were incapable of providing the high intensity needed to adequately protect fibre and muscle mass, and that the crew's ability to perform strenuous exercise might be seriously compromised. Our results highlight the need to study new exercise programmes on the ISS that employ high resistance and contractions over a wide range of motion to mimic the range occurring in Earth's 1 g environment