The physiological functions of expiratory isoprene, which is abundantly contained in human breath, are not well known. Recently, breath isoprene has been proposed to be related to oxidative stress, although no direct evidence has been reported. Therefore, the purpose of this study was to investigate the relationship between breath isoprene and oxidative stress status. Ten healthy male subjects performed a 20-min submaximal step-load cycling exercise, the intensity of which corresponded to a 60% peak oxygen uptake after a 10-min rest. Breath isoprene excretion during the exercise was calculated from the product of minute ventilation and isoprene expiratory concentration. To evaluate the oxidative stress, we collected blood samples from the subject’s fingertips before and immediately after the end of the exercise, and then diacron reactive oxygen metabolites (d-ROMs), which is an index of oxidative stress level, and biological antioxidant potential (BAP), which is an index of antioxidant potential, were measured. The breath isoprene concentration at the rest was significantly positively correlated with the ratio from BAP to d-ROMs (BAP/d-ROMs), which is an index of latent antioxidant potential (r = 0.63, P < 0.05). Furthermore, the change in breath isoprene excretion from before to after the exercise was significantly negatively correlated with the change in d-ROMs (r = -0.73, P < 0.05) and positively correlated with the change in BAP/d-ROMs (r = 0.88, P < 0.01). These results suggest that isoprene might play a role in the control of oxidative stress.
In this study, we performed echo intensity obtained from ultrasonographic images was used as a reference for intramuscular fat mass to determine whether intramuscular fat can be estimated non-invasively using the bioelectrical impedance method. The subjects were 45 healthy male university students (mean age 20.2±1.4 years) of the athletic club. An ultrasound images were taken from vastus lateralis, and the echo intensity was calculated from the obtained image using image analysis software. The impedance corresponding to each of the 17 points from 4to 700 kHz were collected using a multi-frequency impedance measuring device. In addition, intracellular resistance and extracellular resistance were calculated using Cole-Cole distribution model. Pearson’s correlation coefficient was used for the relationship between echo intensity and impedance. As a result, when using a frequency of 50 kHz or more, we observed a moderate correlation (r=0.529 ~ 0.597, p<0.001) between an impedance of 2cm at the distance between the sensing (V) and current (I) electrodes and echo intensity at 2cm from the skin surface. A moderate correlation (r=0.551, p<0.001) was observed between the intracellular resistance at the V-I electrode spacing of 2cm and echo intensity at 2cm form the skin surface. However, there was only a weak correlation between extracellular resistance and echo intensity. This suggests that the impedance and intracellular resistance measured at a frequency of 50 kHz or higher and with a V-I electrode spacing of 2cm reflect intramuscular fat.
Heat-not-burn (HNB) tobacco smoking has spread throughout the market. While it is suggested that HNB tobacco smoking reduces the vascular endothelial function and is associated with a high risk of developing cardiovascular disease. The antioxidant of vitamin C may attenuate the unfavorable effects of HNB tobacco smoking. In the present study, we examined the effect of oral vitamin C ingestion on the flow-mediated dilation (FMD) at the brachial artery and oxidative stress markers in patients before and after transient HNB tobacco smoking. Twelve healthy adult males underwent high-resolution ultrasonography of the brachial artery and evaluations of reactive oxygen metabolites (d-ROMs) and the biological antioxidant potential (BAP) before and after a single session of HNB smoking. FMD was used to examine the endothelial function and the oxidative stress and antioxidant status were determined by using a FRES4 analyzer. In this randomized, crossover, controlled trial, measurements were performed on 2 different days 20 min after the oral administration of 1000 mg of ascorbic acid (VC trial) or a placebo (P trial). Although the FMD values decreased after a single HNB smoking session in both trials, the VC trial showed significantly higher values than the P trial at 60 and 120 min after smoking. Whereas the FMD values 120 min after smoking in the P trial were lower compared to the Pre values, there was no difference in the VC trial. These results suggested that the ingestion of vitamin C might suppress the decrease in the endothelial function caused by a single HNB smoking.