Koji Nonaka

Electrically stimulated ventilation feedback improves the ventilation pattern in patients with COPD

[Purpose] We aimed to determine the effects of ventilation feedback using electrical stimulation on ventilation pattern during exercise in patients with chronic obstructive pulmonary disease (COPD), and develop new rehabilitation methods. [Subjects] This randomized double-blind placebo-controlled trial included 24 patients with COPD. [Methods] Phasic electrical stimulation during expiration (PESE) or a placebo was given to all the cases. Minute ventilation (VE), tidal volume (TV), respiratory rate (RR), expiratory time (Te), total respiratory time (Ttot), dead-space gas volume to tidal gas volume (VD/VT), oxygen uptake (VO2), carbon dioxide output (VCO2), Borg scale (Borg), and percutaneous oxygen saturation (SpO2) during rest and exercise were assessed. [Results] The placebo group showed no obvious change in ventilation measurements at rest or during exercise. However, in the PESE group, TV, Te, and Ttot significantly increased, while RR and VD/VT significantly decreased during exercise compared with the baseline measurements. Borg scores, SpO2, VO2, or VCO2 did not differ significantly. [Conclusion] PESE improves the ventilation pattern during rest and exercise. Furthermore, PESE does not increase VO2, which may indicate an increased workload. Biofeedback may contribute to PESE effects. Stimulation applied during expiration may evoke sensations increasing prolonged expiration awareness, facilitating prolongation.

Changes in antioxidant enzymes and lipid peroxidation in extensor digitorum longus muscles of streptozotocin-diabetic rats may contribute to muscle atrophy.

We investigated muscle atrophy, major antioxidant enzymes and lipid peroxidation in the extensor digitorum longus (EDL, predominantly fast fibers) and soleus (predominantly slow fibers) muscle of streptozotocin-diabetic rats. Female Wistar rats were divided into a control (n = 5) and streptozotocin-induced diabetic group (n = 5). Eight weeks after diabetes induction the EDL and soleus muscles were removed and catalase (CAT), glutathione peroxidase (GPX) and superoxide dismutase activity (SOD), and thiobarbituric acid reactive substances (TBARS) levels measured. The CAT activity increased in both the EDL and soleus muscles of the diabetic rats (p < 0.01), whereas the GPX and SOD activities were increased only in the EDL muscle (p < 0.01 and p < 0.05). The TBARS levels were only increased in the EDL muscle of the diabetic rats (p < 0.01). Both muscles showed significant atrophy but the EDL muscle elicited the greatest atrophy. In conclusion, it appears that adaptive responses to oxidative stress were adequate in the soleus muscle, but not in the EDL muscle, of diabetic rats. Thus fast twitch muscle fibers may be more susceptible to oxidative stress than slow twitch muscle fibers and this may contribute to muscle atrophy under diabetic conditions.

Effects of Hull Scratching, Soaking, and Boiling on Antinutrients in Japanese Red Sword Bean (Canavalia gladiata)

The effects of hull processing, soaking, and boiling on the content or activity of antinutrients in the red sword bean (RSB; Canavalia gladiata) were investigated. RSB seeds were compared with kidney bean (KB; Phaseolus vulgaris) seeds that are starch based and often used as processed products in Japan. RSB seeds had higher weight, thicker hull, and higher protein content, but lower moisture content compared with KB seeds. Because of the strong and thick hull, the relative water absorption of untreated RSB seeds was very low after soaking. Seeds were soaked after dehulling, scratching, and roasting. The results showed that hull scratching was the optimal method for increasing water absorption during soaking compared with dehulling and roasting. After soaking, the water used for soaking was discarded, since it had a high content of polyphenols and bitter taste, and RSB seeds were boiled in fresh water for 20, 40, and 60 min. The results showed that polyphenol and tannin contents, antioxidant activity, and hemagglutinating activity, as well as maltase, sucrase, and trypsin inhibitor activities in scratched RSB seeds decreased significantly after boiling compared with those in raw seeds, whereas amylase inhibitor activity showed no significant change. Overall, it was concluded that the combination of hull scratching, soaking, and boiling in fresh water can reduce thermal-stable or sensitive antinutrients in RSB and thus, significantly improve its nutritional value.

Surface electromyography activity of the rectus abdominis, internal oblique, and external oblique muscles during forced expiration in healthy adults

We aimed to characterize rectus abdominis, internal oblique, and external oblique muscle activity in healthy adults under expiratory resistance using surface electromyography. We randomly assigned 42 healthy adult subjects to 3 groups: 30%, 20%, and 10% maximal expiratory intraoral pressure (PEmax). After measuring 100% PEmax and muscle activity during 100% PEmax, the activity and maximum voluntary contraction of each muscle during the assigned experimental condition were measured. At 100% PEmax, the external oblique (p<0.01) and internal oblique (p<0.01) showed significantly elevated activity compared with the rectus abdominis muscle. Furthermore, at 20% and 30% PEmax, the external oblique (p<0.05 and<0.01, respectively) and the internal oblique (p<0.05 and<0.01, respectively) showed significantly elevated activity compared with the rectus abdominis muscle. At 10% PEmax, no significant differences were observed in muscle activity. Although we observed no significant difference between 10% and 20% PEmax, activity during 30% PEmax was significantly greater than during 20% PEmax (external oblique: p<0.05; internal oblique: p<0.01). The abdominal oblique muscles are the most active during forced expiration. Moreover, 30% PEmax is the minimum intensity required to achieve significant, albeit very slight, muscle activity during expiratory resistance.

Carbon Dioxide Water Bathing Enhances Myogenin but Not MyoD Protein Expression after Skeletal Muscle Injury

[Purpose] We reported that carbon dioxide (CO2) water bathing accelerates skeletal muscle regeneration; however, the underlying mechanism was unclear. MyoD and myogenin play roles in muscle regeneration, and the purpose of this study was to determine changes in MyoD and myogenin caused by CO2 water bathing after injury. [Subjects] Sixteen female Wistar rats (n = 4 per group) were used. [Methods] The rats were divided into four groups: no-injury (NI), injury (IC), injury + tap water bathing (ITW), and injury + CO2 water bathing (ICO2). Muscle injury was induced by injection of bupivacaine hydrochloride into the left tibial anterior (TA) muscles. Tap water and CO2 (1,000 ppm) water bathing were performed at 37 °C for 30 minutes once a day. The left TA muscles were removed 4 days after injury, and the expressions of MyoD and myogenin were measured. [Results] MyoD and myogenin were increased in the IC, ITW, and ICO2 groups compared with the NI group. Although the MyoD level was similar in the IC, ITW, and ICO2 groups, myogenin increased more in the ICO2 group than in the IC and ITW groups. [Conclusion] CO2 water bathing after muscle injury appears to induce an increase in the expression of myogenin.

Heat stress attenuates skeletal muscle atrophy of extensor digitorum longus in streptozotocin-induced diabetic rats

To investigate whether heat stress attenuates skeletal muscle atrophy of the extensor digitorum longus (EDL) muscle in streptozotocin-induced diabetic rats, 12-week-old male Wistar rats were randomly assigned to four groups (n = 6 per group): control (Con), heat stress (HS), diabetes mellitus (DM), and diabetes mellitus/heat stress (DM + HS). Diabetes was induced by intraperitoneal injection of streptozotocin (50 mg/kg). Heat stress was induced in the HS and DM + HS groups by immersion of the lower half of the body in hot water at 42 °C for 30 min; it was initiated 7 days after injection of streptozotocin, and was performed once a day, five times a week for 3 weeks. The muscle fiber cross-sectional area of EDL muscles from diabetic and non-diabetic rats was determined; heat stress protein (HSP) 72 and HSP25 expression levels were also analyzed by western blotting. Diabetes-induced muscle fiber atrophy was attenuated upon heat stress treatment in diabetic rats. HSP72 and HSP25 expression was upregulated in the DM + HS group compared with the DM group. Our findings suggest that heat stress attenuates atrophy of the EDL muscle by upregulating HSP72 and HSP25 expression.

Effect of Skeletal Muscle and Fat Mass on Muscle Strength in the Elderly

It is important for elderly people to maintain or improve muscle strength and for clinicians to know the factors that affect muscle strength. Therefore, the purpose of this study was to compare the effects of fat mass (FM) and skeletal muscle mass (SMM) on muscle strength. The participants included 192 community-dwelling elderly women. The SMM and FM, grip strength, and knee extension strength were measured. Data were evaluated using stepwise multiple linear regression analysis, which was performed with grip or knee extension strength as a dependent variable and the SMM and FM of the upper and lower limbs as the independent variables. The SMM and FM of the upper limbs were associated with grip strength, whereas the SMM but not the FM of the lower limbs was associated with knee extension strength. These findings suggest that there may be thresholds for the SMM/FM ratio to affect muscle strength.

Electrical stimulation ventilatory feedback facilitates maintenance of a prolonged expiration pattern during exercise: A proof-of-concept study in healthy adults

ABSTRACT This study aimed at verifying the safety and effects of electrical stimulation ventilatory feedback (ESVF) to provide feedback during expiration, which may assist with breathing control in patients with chronic obstructive pulmonary disease (COPD). Because this is a new therapy, we examined the feasibility of the therapy in healthy adults. The 23 healthy adult participants were randomized into two groups: a stimulation group that received ESVF and a placebo group with the ESVF device attached, but not activated. Sensory stimulation was provided at a frequency of 20 Hz and pulse duration of 200 μs. During breathing training, participants practiced a prolonged expiration pattern and were instructed to maintain the breathing pattern during exercise. A variety of parameters such as respiratory time from the gas analyzer monitor and quantitative load were measured during lower-extremity cycle ergometer exercise. The primary outcome was the expiratory to inspiratory time ratio, which was significantly higher in the stimulation group than in the placebo group, both during and after exercise. No side effects were reported during the use of electrical stimulation. Therefore, ESVF is safe and facilitates maintenance of a prolonged expiration pattern during and after exercise.