Biomedical subjects

David R Strayer

Publications and source records attributed to David R Strayer.

3 recordsLinked to original sources

PubMed2003

Subclassifying chronic fatigue syndrome through exercise testing.

PURPOSE: The purpose of this study was to examine physiological responses of persons with chronic fatigue syndrome (CFS) to a graded exercise test. METHODS: Cardiopulmonary exercise tests were performed on 189 patients diagnosed with CFS. Based on values for peak oxygen consumption, patients were assigned to one of four impairment categories (none, mild, moderate, and severe), using American Medical Association (AMA) guidelines. A one-way MANOVA was used to determine differences between impairment categories for the dependent variables of age, body mass index, percentage of predicted [OV0312]O(2), resting and peak heart rates, resting and peak systolic blood pressure, respiratory quotient (RQ), and rating of perceived exertion. RESULTS: Significant differences were found between each impairment level for percentage of predicted [OV0312]O(2) and peak heart rate. Peak systolic blood pressure values for the "moderate," and "severe" groups differed significantly from each other and both other groups. The more impaired groups had lower values. The no impairment group had a significantly higher peak RQ than each of the other impairment levels (all P < 0.001). Peak [OV0312]O(2) values were less than predicted for all groups. Compared with the males, the women achieved actual values for peak [OV0312]O(2) that were closer to their predicted values. CONCLUSION: Despite a common diagnosis, the functional capacity of CFS patients varies greatly. Stratifying patients by function allows for a more meaningful interpretation of the responses to exercise and may enable differential diagnosis between subsets of CFS patients.

Adult↗

PubMedDate not supplied

Physical performance and prediction of 2-5A synthetase/RNase L antiviral pathway activity in patients with chronic fatigue syndrome.

The elevated RNase L enzyme activity observed in some Chronic Fatigue Syndrome (CFS) patients may be linked to the low exercise tolerance and functional impairment that typify this disease. The purpose of this investigation was to determine if specific indicators of physical performance can predict abnormal RNase L activity in CFS patients. Seventy-three CFS patients performed a graded exercise test to voluntary exhaustion. Forty-six patients had elevated RNase L levels. This measure was employed as the dependent variable in a discriminant function analysis, with peak V02, exercise duration and Karnofsky Performance Scores (KPS) serving as the independent variables. All three variables entered the single significant function (p < 0.001). The elevated RNase L group had a lower peak V02 and duration than the normal group, but a higher KPS. The results suggest that both exercise testing and the RNase L biomarker have potential to aid in the diagnosis of CFS.

2',5'-Oligoadenylate Synthetase↗

PubMedDate not supplied

Exercise capacity and immune function in male and female patients with chronic fatigue syndrome (CFS).

Hyperactivition of an unwanted cellular cascade by the immune-related protein RNase L has been linked to reduced exercise capacity in persons with chronic fatigue syndrome (CFS). This investigation compares exercise capacities of CFS patients with deregulation of the RNase L pathway and CFS patients with normal regulation, while controlling for potentially confounding gender effects. Thirty-five male and seventy-one female CFS patients performed graded exercise tests to voluntary exhaustion. Measures of peak VO2, peak heart rate, body mass index, perceived exertion, and respiratory quotient were entered into a two-way factorial analysis with gender and immune status as independent variables. A significant multivariate main effect was found for immune status (p < 0.01), with no gender effect or interaction. Follow-up analyses identified VO2(peak) as contributing most to the difference. These results implicate abnormal immune activity in the pathology of exercise intolerance in CFS and are consistent with a channelopathy involving oxidative stress and nitric oxide-related toxicity.

Adult↗