Validation of Salivary Interleukin-6 and Tumor Necrosis Factor-Alpha of Healthy Adult Volunteers by Enzyme Immunoassay.

BACKGROUND: Despite the use of saliva with enzyme immunoassay (EIA) methods validated for use with blood to measure interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), there has been limited validation of saliva as a matrix for EIA of IL-6 and TNF-α. OBJECTIVES: The study aims were to (a) validate one vendor's commercially available EIAs for detecting IL-6 and TNF-α in saliva as an alternative matrix to blood and (b) test the long-term stability of EIA detection of IL-6 and TNF-α after 12-month storage of saliva and plasma. METHODS: Spike and recovery and linearity experiments were performed. Concentrations of IL-6 and TNF-α in saliva and plasma from 20 healthy adult volunteers (6 men and 14 women) were correlated; the assays were repeated 12 months later. RESULTS: Spike and recovery and linearity performance was adequate for salivary IL-6: intra-assay percentage coefficient of variation, less than or equal to 8.4%; sensitivity, 0.11 pg/ml; mean recoveries, 81% in spiked saliva and 110% in spiked controls; and linearity, r = .995. The association between IL-6 in saliva and plasma was moderate and significant (p = .04). Spike and recovery and linearity performance was inadequate for TNF-α: intra-assay coefficient of variation, 10.8%; sensitivity, 2.3 pg/ml; mean recoveries, 44% in spiked saliva and 92% in spiked controls; and linearity, r = .950. The association between TNF-α in saliva and plasma was low and insignificant. Plasma and saliva IL-6 levels were significantly higher (p < .0001), and plasma and saliva TNF-α levels were significantly lower (p < .0001) after 12-month storage of specimens. DISCUSSION: We concluded that (a) saliva can be used to assess IL-6, but not TNF-α, with an EIA validated for use with blood and (b) 12-month storage of plasma and saliva significantly changes the assay results. Validation of other EIAs would expand assay options for investigators.

Effects of quadriceps strength after static and dynamic whole-body vibration exercise.

Numerous studies have shown performance benefits including whole-body vibration (WBV) as a training modality or an acute exercise protocol when used as a component of the resistance training program. Some studies have indicated that performing dynamic exercises as compared with static position exercises while exposed to WBV might be beneficial; however, evidence is lacking. Thus, the purpose of this study was to determine if an acute bout of dynamic versus static squats performed during WBV results in increase in quadriceps force production by means of dynamic isokinetic knee extension and flexion exercise. Nonresistance-trained healthy young men and women (N = 21) of 18-25 years participated in 4 protocols with 2-week rest in-between. Protocol 1 consisted of 5 sets of 10 dynamic squats without vibration; Protocol 2: 5 sets of 30-second static squats without vibration; Protocol 3: 5 sets of 10 dynamic squats with 30-Hz WBV for a total of 2.5 minutes; and Protocol 4: 5 sets of 30-second static squats with 30-Hz WBV for a total of 2.5 minutes. Prestrength tests (1 set of 4 repetitions at 100° · s(-1) for the knee extension exercise) was performed within 5 minutes of starting each protocol, and poststrength testing was performed within 1 minute of completing each protocol. Strength outcomes were analyzed by repeated measures analysis of variance with a significance level set at p ≤ 0.05. A significant decrease in strength was observed after dynamic and static squats without WBV (p = 0.002); an increase in strength after dynamic squats with WBV (p = 0.003); and a decrease in strength after static squats with WBV (p = 0.003). The inclusion of WBV to dynamic resistance exercise can be an added modality to increase strength. Whole-body vibration can have varied effects in altering muscle strength in untrained individuals according to the type of resistance training performed. As a dynamic squat with WBV seems to immediately potentiate neuromuscular functioning, the combination of dynamic exercises and WBV could be used as a potential warm-up procedure before resistance exercise.