Despite its advantages as a chronobiological technique, the ultra-short sleep/wake protocol remains underutilized in circadian rhythm research. The purpose of this study was to examine circadian rhythms of psychomotor vigilance (PVT), mood, and sleepiness in a sample (n=25) of healthy young adults while they adhered to a 3 h ultra-short sleep/wake protocol. The protocol involved 1 h sleep intervals in darkness followed by 2 h wake intervals in dim light, repeated for 50–55 h. A 5 min PVT test was conducted every 9 h with the standard metrics of mean reaction time (RT; RTmean), median RT (RTmed), fastest 10% of responses (RT10fast), and reciprocal of the 10% slowest responses (1/RT10slow). Subjective measures of mood and sleepiness were assessed every 3 h. A cosine fit of intra-aural temperature, assessed three times per wake period, established the time of the body temperature minimum (Tmin). Mood, sleepiness, and PVT performances were expressed relative to individual means and compared across eight times of day and twelve 2 h intervals relative to Tmin. Significant time-of-day and circadian patterns were demonstrated for each of the PVT metrics, as well as for mood and sleepiness. Most mood subscales exhibited significant deterioration in day 2 of the protocol without alteration of circadian pattern. However, neither sleepiness nor performance was worse on the second day of observation compared to the first day. These data provide further support for the use of the ultra-short sleep/wake protocol for measurement of circadian rhythms. (Author correspondence: syoungstedt@sc.edu)
Moderate exercise training may decrease the risk of URTI while strenuous exercise has been associated with increased risk. Consumption of oat beta-glucan (Obg), a soluble fiber and mild immune system enhancer, may further enhance immune function associated with moderate exercise training. PURPOSE: We studied the effects of short-term moderate exercise training and Obg on susceptibility to infection using our mouse model of respiratory infection (Davis et.al. J. Appl. Physiol. 83 (5): 1461–6 1997). Macrophage (Mo) anti-viral resistance was also determined as a potential mechanism of this effect. METHODS: Male CD-1 mice (n = 96) were randomly assigned to one of four groups. Exercise mice (EX-obg and EX-h2o) ran for I h on a treadmill for 6 consecutive days at 36m/min, 8% grade. Control mice (C-obg and C-h2o) were exposed to the same environment, but remained in their cages throughout the exercise period. Obg was consumed in the drinking water (3.6mg/day) (EX-obg and C-obg) for 10 consecutive days prior to virus inoculation. Following rest or exercise on the last day of training, mice were intra-nasally inoculated with herpes simplex virus-1 (HSV-1). They were monitored twice daily for morbidity and mortality for 21 days. Additional mice (n = 48) were sacrificed following exercise; peritoneal macrophages were obtained via i.p. lavage and assayed for anti-viral resistance to HSV-1. RESULTS: EX decreased morbidity by 46% and mortality by 38% (P < 0.05). EX also increased Mo anti-viral resistance (P < 0.05). Obg did not further enhance immune function in exercise animals. However, in control mice it did decrease both morbidity and mortality and increased Mo anti-viral resistance (P < 0.05). CONCLUSION: These data suggest that although not additive in their effects both moderate exercise training and Obg consumption may decrease the risk of URTI. This may be mediated at least in part, by an increase in Mo anti-viral function.
Cancer cachexia induces unexplained weight loss thought to be mediated by chronic inflammation and increases the risk of mortality. However, less is known about the effect of chronic inflammation on the heart. PURPOSE The purpose of this study was to determine cardiac remodeling and inflammation in the hearts of APCmin+/− mice, a model of colorectal cancer that experiences chronic low levels of inflammation and cachexia. METHODS Seven female APCmin+/− (6mo) and seven female C57B/L6 (wt) mice were used in this study. Body and heart mass and tibia length were determined. RT-PCR was used to determine gene expression related to cardiac remodeling and cardiac inflammation. RESULTS Body mass was 20% lower in APCmin+/− than wt (22.1 ± 1.1 vs 27.8 ± .6g, p<.05) though body size (tibia length) was not different (16.7 ± .1 vs 16.7 ± .1mm). APCmin+/− hearts were 25% heavier than wt hearts (160.9 ± 6.5 vs 128.4 ± 4.4mg, p<.05). αMHC mRNA expression was 25% lower in APCmin+/− hearts compared to wt (.74 ± .03 vs 1.0 ± .06 IOD, p<.05) and skeletal-α-actin mRNA expression was 50% lower in APCmin+/− compared to wt hearts (.49 ± .05 vs 1.0 ± .05 IOD, p<.05). Cardiac IL-6 mRNA expression was 50% greater in APCmin+/− than wt hearts (1.5 ± .2 vs 1.0 ± .2 IOD, p<.05). CONCLUSIONS In conclusion, the cachectic mice have enlarged hearts that show significant cardiac remodeling and enhanced local inflammation. Further work is needed to determine if chronic inflammation is inducing the cardiac enlargement and remodeling processes.
Moderate exercise training is associated with a decreased risk for upper respiratory tract infection in human and animal studies, but the mechanisms have not been elucidated. Lung macrophages play an important role in resistance to respiratory infection, and moderate exercise can enhance macrophage antiviral resistance, but no studies have directly tested the role of lung macrophages in this response. This study tested the effect of lung macrophage depletion on susceptibility to infection following short-term moderate exercise training. Mice were assigned to one of four groups: exercise (Ex) and resting controls (Con) with and without clodronate encapsulated liposomes (CL(2)MDP-lip). Ex mice ran for 1 h on a treadmill for 6 days at 36 m/min, 8% grade. Fifteen minutes following exercise or rest on the last day of training, mice were intranasally inoculated with a standardized dose of herpes simplex virus type 1. Clodronate (Ex-CL(2)MDP-lip and Con-CL(2)MDP-lip) or PBS liposomes (Ex-PBS-lip and Con-PBS-lip) (100 microl) were intranasally administered following exercise or rest on the 4th day of training and again on the 4th day postinfection. Morbidity, mortality, and symptom severity were monitored for 21 days. Exercise decreased morbidity by 36%, mortality by 61%, and symptom severity score on days 5-7 (P < 0.05). Depletion of lung macrophages negated the beneficial effects of moderate exercise. This was indicated by no differences between Ex-CL(2)MDP-lip and Con-PBS-lip in morbidity (89 vs. 95%), mortality (79 vs. 95%), or symptom severity. Results indicate that lung macrophages play an important role in mediating the beneficial effects of moderate exercise on susceptibility to respiratory infection.
PURPOSE: To measure the influence of the antioxidant flavonol molecule, quercetin (Q), on plasma cytokines, leukocyte cytokine mRNA, plasma cortisol, muscle damage, C-reactive protein (CRP), and delayed onset of muscle soreness (DOMS) in ultra-marathoners competing in the 160-km Western States Endurance Run (WSER). METHODS: Sixty-three runners were randomized to Q and placebo (P) groups, and under double blinded methods ingested 1000 mg/day Q for 3 wks before, during, and 2 wks after the WSER. Thirty-nine of the 63 subjects (N=18 for Q, N=21 for P) finished the race, provided blood samples the morning before the race and 15–30 min post-race, and recorded DOMS during the week after the race using a 10-point Likert scale. RESULTS: Significant pre-to-post WSER increases were measured for 10 pro- and anti-inflammatory plasma cytokines, cortisol (Q=94%, P=96%), serum CRP (absolute increase, Q=318 and P=381 mg/L), and creatine kinase (CK) (absolute increase, Q=21574 and P=19472 U/L), with no significant group differences. DOMS peaked the day after the WSER (6.8±0.4 and 7.3±0.4 for Q and P, respectively, P=0.377) with no group differences seen during the 7-day post-WSER period. IL-6 mRNA did not change post-WSER, with a decrease measured for leukocyte IL-8 mRNA (0.21 and 0.25 fold change from rest, Q and P respectively), and increases for IL-1ra and IL-10 mRNA (12.9 and 17.2 fold change, respectively), with no significant group differences. CONCLUSION: Q supplementation for 3 wks before and 2 wks after the WSER had no effect on increases in plasma levels for 10 cytokines, cortisol, serum CRP, changes in leukocyte mRNAfor IL-8, IL-1ra, IL-10, and IL-6, muscle damage, and DOMS.
Purpose: This study investigated the effects of oat β-glucan (BG) supplementation on chronic resting immunity, exercise-induced changes in immune function, and self-reported upper respiratory tract infection (URTI) incidence in human endurance athletes. Methods: Trained male cyclists were randomized to BG (N = 19) or placebo (P; N = 17) groups and under double-blind procedures received BG (5.6 g·d−1) or P beverage supplements for 2 wk before, during, and 1 d after a 3-d period in which subjects cycled for 3 h·d−1 at approximately 57% maximal watts. URTI symptoms were monitored during BG supplementation and for 2 wk afterward. Blood samples were collected before and after 2 wk of supplementation (both samples, 8:00 a.m.), immediately after the 3-h exercise bout on day 3 (6:00 p.m.), and 14 h after exercise (8:00 a.m.) and were assayed for natural killer cell activity (NKCA), polymorphonuclear respiratory burst activity (PMN-RBA), phytohemagglutinin-stimulated lymphocyte proliferation (PHA-LP), plasma interleukin 6 (IL-6), IL-10, IL-1 receptor agonist (IL-1ra), and IL-8, and blood leukocyte IL-10, IL-8, and IL-1ra mRNA expression. Results: Chronic resting levels and exercise-induced changes in NKCA, PMN-RBA, PHA-LP, plasma cytokines, and blood leukocyte cytokine mRNA did not differ significantly between BG and P groups. URTI incidence during the 2-wk postexercise period did not differ significantly between groups. Conclusions: An 18-d period of BG versus P ingestion did not alter chronic resting or exercise-induced changes in immune function or URTI incidence in cyclists during the 2-wk period after an intensified exercise.
