Notes

Phenotypic and functional variation within venom as well as venom level of resistance regarding a couple of sympatric rattlesnakes and their victim.
This study aimed to compare cerebral oxyhemoglobin (O2Hb) levels during incremental exercise by cycling vs. arm cranking in 12 healthy adult men aged 20.8 ± 0.2 years old. selleck chemical O2Hb was measured by near-infrared spectroscopy. Regions of interest included the left and right prefrontal cortices (LtPFC and RtPFC, respectively), the left and right premotor cortices (LtPMC and RtPMC, respectively), and the supplementary motor area (SMA) bilaterally. After 4 min of rest, 4 min of warm-up was performed by using ergometer followed by incremental exercise (increasing work rate by 5 W/min for arm cranking and 20 W/min for cycling exercise). All values were averaged every tenth of the participant's exercise time period from beginning of incremental exercise to end point. At the middle exercise intensity (50% exercise time), the averaged O2Hb values obtained at all regions of interest seemed to be higher during arm cranking exercise as compared to cycling; however, there were no significant differences between two types of exercise. At the end point of incremental exercise (100% exercise time), the O2Hb obtained at all regions of interest was significantly higher during arm cranking exercise compared to cycling (LtPFC 0.081 ± 0.019 vs. -0.001 ± 0.013 mM·cm, RtPFC 0.076 ± 0.021 vs. 0.018 ± 0.015 mM·cm, SMA 0.012 ± 0.040 vs. 0.040 ± 0.016 mM·cm; arm cranking vs. cycling; p less then 0.05, respectively). We conclude that exercise-induced cerebral oxygenation is greater with arm cranking than with leg cycling.A previous study considered that a decrease in cerebral oxyhemoglobin (O2Hb) immediately before maximal exercise during incremental exercise is related to cerebral blood flow (CBF) and partial pressure end-tidal carbon dioxide (PETCO2). This study aimed to investigate the relationship between O2Hb, PETCO2, and the estimated value of cerebral blood volume (CBV) with cerebral oxygen exchange (COE) by using vector analysis. Twenty-four healthy young men participated in this study. They performed the incremental exercise (20 W/min) after a 4-min rest and warm-up. The O2Hb and deoxyhemoglobin (HHb) in the prefrontal cortex (PFC) were measured using near-infrared spectroscopy (NIRS). The PETCO2 was measured using a gas analyzer. The O2Hb, HHb, and PETCO2 were calculated as the amount of change (ΔO2Hb, ΔHHb, and ΔPETCO2) from an average 4-min rest. Changes in the CBV (ΔCBV) and COE (ΔCOE) were estimated using NIRS vector analysis. Moreover, the respiratory compensation point (RCP), which relates to the O2Hb decline, was detected. The Pearson correlation coefficient was used to establish the relationships among ΔO2Hb, ΔPETCO2, ΔCBV, and ΔCOE from the RCP to maximal exercise. The ΔPETCO2 did not significantly correlate with the ΔO2Hb (r = 0.03, p = 0.88), ΔCOE (r = -0.19, p = 0.36), and ΔCBV (r = -0.21, p = 0.31). These results showed that changes in the ΔPETCO2 from the RCP to maximal exercise were not related to changes in the ΔO2Hb, ΔCOE, and ΔCBV. Therefore, we suggested that the decrease of O2Hb immediately before maximal exercise during incremental exercise may be related to cerebral oxygen metabolism by neural activity increase, not decrease of CBF by the PETCO2.A recent study based on near-infrared spectrometry (NIRS) showed that a single session of moderate-intensity exercise increases the cortical oxyhemoglobin (O2Hb) level. However, changes in the laterality of O2Hb throughout such exercises remain unknown. In the present study, we evaluated changes in the laterality of O2Hb in the prefrontal cortex (PFC) and premotor area (PMA) during moderate-intensity cycling for 20 min. Twelve healthy volunteers performed the exercise at 50% of the maximal oxygen consumption after a 3-min rest period. O2Hb levels in the right (R-) and left (L-) PFC and PMA were measured using multichannel NIRS and averaged every 5 min during the exercise period, and the laterality index (LI) for each 5-min period was calculated. LI for PFC showed significant changes in each period (first, second, third, and fourth periods -0.40 ± 0.21, -0.03 ± 0.12, 0.14 ± 0.15, and 0.16 ± 0.10, respectively; p less then 0.05), whereas that for PMA showed no significant changes (-0.07 ± 0.09, 0.23 ± 0.08, 0.17 ± 0.12, and 0.19 ± 0.09, respectively; p = 0.12). These findings suggest that the laterality of cortical oxygenation in PFC of healthy, young individuals changes during moderate-intensity exercise for 20 min, thus providing an insight into the mechanisms underlying exercise-induced improvements in brain function.Previous studies have reported that the reduced scattering coefficient (μs') in the vastus lateralis changes during ramp-incremental exercise due to blood volume changes or accumulation of metabolic by-products. We aimed to clarify the influences of deoxygenation and blood volume changes during exercise on μs' dynamics in subjects with various aerobic capacities. Twenty-three healthy young men participated in this study. All subjects performed a ramp-incremental cycling exercise until exhaustion and were divided into two groups lower (Low n = 12; peak pulmonary oxygen uptake per kg of fat-free mass (VO2peak), 54.2 ± 5.3 mL/kg/min) and higher aerobic capacity group (High n = 11; VO2peak, 69.7 ± 5.2 mL/kg/min) by median of VO2peak. Deoxygenated hemoglobin and myoglobin concentrations (deoxy[Hb + Mb]) and total [Hb + Mb] (total[Hb + Mb]) in the vastus lateralis were monitored during the exercise by three-wavelength (760, 800, and 830 nm) time-resolved NIRS. Similarly, μs' at each wavelength was continuously monitored. With increasing exercise intensity, deoxy[Hb + Mb] and total[Hb + Mb] significantly increased in both groups, and the average values of the peak amplitudes of deoxy[Hb + Mb] and total[Hb + Mb] during exercise showed a 106.4% increase and a 17.9% increase from the start of the exercise, respectively. Furthermore, the peak amplitude of total[Hb + Mb] was significantly greater in High. Conversely, there were no changes in μs' at any wavelength during exercise and no differences between two groups, suggesting that the great deoxygenation and blood volume changes during incremental exercise have little effect on μs' dynamics.
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