First Observation of B 20 and B 21 Leblond, S.; Marqués, F. M.; Gibelin, J. ...
Physical review letters,
12/2018, Letnik:
121, Številka:
26
Journal Article
Background. Muscle power (force × velocity) recedes at a faster rate than strength with age and may also be a stronger predictor of fall risk and functional decline. The optimal training paradigm for ...improving muscle power in older adults is not known, although some literature suggests high velocity, low load training is optimal in young adults. Methods. One hundred twelve healthy older adults (69 ± 6 years) were randomly assigned to either explosive resistance training at 20% (G20), 50% (G50), or 80% (G80) one repetition maximum (1RM) for 8–12 weeks or to a nontraining control group (CON). Participants trained twice per week (five exercises; three sets of eight rapidly concentric and slow eccentric repetitions) using pneumatic resistance machines. Repeated-measures analysis of variance and covariance (ANOVA and ANCOVA) were used to determine the effects of training. Results. Average peak power increased significantly and similarly in G80 (14 ± 8%), G50 (15 ± 9%), and G20 (14 ± 6%) compared to CON (3 ± 6%) (p <.0001). By contrast, a positive dose-response relationship with training intensity was observed for relative changes in average strength (r =.40, p =.0009) and endurance (r =.43, p =.0005). Average strength increased in G80 (20 ± 7%), G50 (16 ± 7%), and G20 (13 ± 7%) compared to CON (4 ± 4%) (p <.0001). Average muscle endurance increased in G80 (185 ± 126%, p <.0001), G50 (103 ± 75%, p =.0004), and G20 (82 ± 57%, p =.0078) compared to CON (28 ± 29%). Conclusion. Peak muscle power may be improved similarly using light, moderate, or heavy resistances, whereas there is a dose-response relationship between training intensity and muscle strength and endurance changes. Therefore, using heavy loads during explosive resistance training may be the most effective strategy to achieve simultaneous improvements in muscle strength, power, and endurance in older adults.
Ovarian cancer is a leading cause of cancer mortality in women, and novel treatments with improved efficacy are needed to fight ovarian cancer. Double-stranded (ds) RNA, including the synthetic ...polyinosinic cytidylic acid (poly (I:C), has shown promise as a cancer therapeutic. Phytoglycogen derived from sweet corn, nanodendrix (NDX) is a carrier for dsRNA. The responsiveness to NDX-delivered poly (I:C), NDX-poly (I:C), was tested in two ovarian cancer cell lines, SKOV-3 and OVCAR-3, previously identified as dsRNA-resistant and dsRNA-sensitive, respectively. NDX bound poly (I:C) at a w/w ratio of 2:1 NDX:poly (I:C) and poly (I:C)-NDX was tested for biological activity through uptake and two therapeutic modes of action, cytotoxicity, and immune stimulation. Immunocytochemistry demonstrated both cells bound to poly (I:C)-NDX. In OVCAR-3, poly (I:C)-NDX caused significant cell death, even at concentrations as low as 62.5 ng/mL; no cell death was observed with poly (I:C) alone at concentrations up to 5 μg/mL in SKOV-3 and 0.5 μg/mL in OVCAR-3. In both cell lines poly (I:C)-NDX stimulated the production of CXCL10 protein and transcripts, an innate immune chemokine, and at significantly higher levels than poly (I:C) alone. Interestingly, in response to poly (I:C)-NDX SKOV-3 produced a more robust immune response and higher levels of capase-3/-7 activation compared to OVCAR-3, despite showing no significant cell death. Poly (I:C)-NDX represents a robust and multifunctional therapy, potentiating poly (I:C) and sensitizing resistant cells. Additionally, the SKOV-3 and OVCAR-3 combination represents a powerful comparative model to help unravel dsRNA-mediated immune responses in ovarian cancer cells.
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