RESUMO
The purpose of this study was to investigate the potential of using ruminal pH measurements to track time-series ruminal volatile fatty acid (VFA) concentrations occurring in response to short-term dietary disruption. Four ruminally cannulated dry Holstein dairy cows were individually housed and assigned to 4 treatments in a Latin square design. Treatments differing in forage-to-concentrate (F:C) ratio (100:0 to 55:45) were used because they were expected to result in large differences in VFA concentration, over which the relationships between pH and VFA could be robustly evaluated. Each sampling period lasted 36 h. Animals were removed from pasture and fasted for 24 h, after which time they were fed their treatment ration for 2 h and sampled for rumen fluid hourly for 12 h. Rumen fluid samples were analyzed immediately for pH, frozen, and subsequently analyzed for VFA concentrations using gas chromatography. Animals were returned to pasture for 7 d between sampling periods. To confirm that the short-term dietary disruptions resulted in expected variation in VFA concentrations, mean VFA concentrations during each animal period (n = 16) were analyzed using a linear mixed effects model with fixed (linear and quadratic) effects for F:C ratio and random effects for animal and period. Results indicated significant changes in VFA concentration across F:C ratio, but no significant shifts in VFA molar proportions, perhaps due to the short-term nature of the feeding protocol. To explore opportunity to use pH measurements to explain variability in VFA concentrations in real time across dietary conditions, a linear mixed-effect model was used to link the time-series measurements (n = 207). The VFA concentrations were analyzed with linear mixed effect models using linear and quadratic terms for pH, and random effects for animal and period. These models had poor accuracy, with residual error variance ranging from 21% to 38%, and residuals patterning significantly with F:C ratio. The data suggest that pH may lack reliability for VFA prediction in short-term feeding scenarios differing considerably in F:C ratio.
RESUMO
BACKGROUND: Chronic fatigue syndrome (CFS) is a disabling illness of persistent fatigue. Recent studies have shown that patients with CFS have an increased prevalence of nonallergic rhinitis. Inflammation of the nasal passages due to allergic rhinitis can cause nasal congestion resulting in an increased number of sleep disturbances and daytime fatigue. While topical nasal corticosteroids have been shown to alleviate nasal obstruction effectively in patients with rhinitis who do not have CFS, it is unknown whether topical nasal corticosteroids will reduce CFS symptoms. STUDY OBJECTIVE: The purpose of this study is to determine whether topical nasal corticosteroids will reduce daytime sleepiness in patients with CFS and rhinitis. METHODS: Twenty-eight of 31 subjects with rhinitis and a diagnosis of CFS completed the double-blind, randomized, placebo-controlled trial. Two subjects failed screening, and 3 subjects withdrew from the study prior to its completion. Subjects were randomized according to Balaam's crossover design, and one of the following interventions was used for each group in the study: 8-week treatment with a topical nasal corticosteroid, 8-week treatment with a placebo saline spray, 4-week treatment with a topical nasal corticosteroid followed by a 4-week treatment with a placebo saline spray, or a 4-week treatment with a placebo saline spray followed by a 4-week treatment with a topical nasal corticosteroid. Data focusing on rhinitis symptoms, severity of chronic fatigue symptoms, and quality of life were gathered at biweekly office visits and with daily diaries. RESULTS: The results indicated that daytime sleepiness was reduced when patients with rhinitis and CFS were treated with topical nasal corticosteroids. The severity of associated CFS symptoms, specifically fatigue, muscle pain, postexertional fatigue, and daily activity, did not improve with treatment. CONCLUSION: Treating the symptoms of rhinitis in patients with CFS does not appear to alleviate daytime fatigue or associated nasal, musculoskeletal, or cognitive complaints. Therefore, it is unlikely that aggressive treatment of such symptoms with topical nasal corticosteroids will provide significant benefit to patients with CFS who do not have allergic rhinitis. These results indicate that the nonallergic rhinitis seen in patients with CFS may arise from a mechanism other than chronic inflammation.
