Effects of resistance training intensity on muscle quantity/quality in middle-aged and older people: a randomized controlled trial.

BACKGROUND: A sarcopenia diagnosis is confirmed by the presence of low muscle quantity or quality under the 2018 revised definition by the European Working Group on Sarcopenia in Older People 2. Imaging methods [i.e. magnetic resonance imaging (MRI)], dual-energy X-ray absorptiometry (DXA), and bioelectrical impedance analysis are tools to evaluate muscle quantity or quality. The present study aimed to investigate whether and how low-intensity and moderate-intensity resistance training improved both muscle quantity and quality measured by MRI, DXA, and segmental bioelectrical impedance spectroscopy (S-BIS) in middle-aged and older people. METHODS: A single-blind, randomized, controlled trial was conducted. Community-dwelling people aged 50-79 years were randomly allocated to no exercise (no-Ex), low-intensity exercise (low-Ex), and moderate-intensity exercise (moderate-Ex) groups. Participants in the exercise groups performed resistance training for 24 weeks, with loads of 40% and 60% of one repetition maximum in the low-Ex and moderate-Ex groups, respectively. Cross-sectional area (CSA), lean mass, and muscle electrical properties on S-BIS were used to determine the effects of training interventions on muscle quantity and quality of the lower limbs. RESULTS: Fifty participants (no-Ex 17, age 63.5 ± 8.5 years, women 47.1%; low-Ex 16, age 63.6 ± 8.1 years, women 50.0%; moderate-Ex 17, age 63.5 ± 8.3 years, women 52.9%) completed the 24 week exercise intervention. For the primary outcome, significant intervention effects were found in thigh muscle CSA on MRI between the moderate-Ex and no-Ex groups (+6.8 cm2 , P < 0.01). Low-Ex for 24 weeks only increased quadriceps CSA (+2.3 cm2 , P < 0.05). The per cent change of thigh muscle CSA (+7.0%, P < 0.01) after 24 week moderate-Ex was higher than that of leg lean mass on DXA (+2.3%, P = 0.088). Moderate-Ex for 24 weeks also improved S-BIS electrical properties related to muscle quantity and quality, including the intracellular resistance index (+0.1 cm2 /Ω, P < 0.05), membrane capacitance (+0.7 nF, P < 0.05), and phase angle (+0.3 deg, P < 0.05); their changes were positively correlated with that of thigh muscle CSA (P < 0.01). CONCLUSIONS: Resistance exercise with moderate intensity improved muscle quantity and quality measured by MRI and S-BIS, whereas that with low intensity only increased muscle quantity in middle-aged and older people. The comparisons among the responses to exercise between the assessment methods indicate the greater value of MRI and S-BIS to measure changes of muscle quantity and quality than of lean mass measured by DXA for assessing the local effects of resistance training.

Characteristics of the Passive Muscle Stiffness of the Vastus Lateralis: A Feasibility Study to Assess Muscle Fibrosis.

Skeletal muscle fibrosis occurs with aging and has been suggested to impair muscle performance, thereby decreasing quality of life. Recently, muscle stiffness, a surrogate measure of muscle fibrosis, was noninvasively quantified as the shear modulus using ultrasound shear wave elastography (SWE) in humans. We aimed to investigate thigh muscle stiffness in females and males, respectively, across a broad range of ages by using SWE. Eighty-six community-dwelling Japanese people who were aged 30 to 79 years and did not regularly exercise participated in this study. The vastus lateralis (VL) shear modulus was measured at three different knee joint angles: full extension, 90° of flexion, and full flexion. There were no significant main effects of sex or age on the VL shear modulus in full extension or 90° of flexion of the knee. However, the VL shear modulus in knee full flexion was significantly smaller in females than in males and increased with age from 47.9 years. The results suggest that the accelerated increase in VL stiffness that occurs after an individual passes their late 40s may be an important therapeutic target for developing effective treatments and programs that preserve and improve quality of life.

Comparison of chest compression quality in walking versus straddling cardiopulmonary resuscitation during stretcher transportation: A prospective randomised crossover study using manikins.

The optimal strategy to ensure chest compression quality for patients being transported on a stretcher has not been established yet. We hypothesised that straddling cardiopulmonary resuscitation may improve chest compression quality in patients being transported on stretchers. We conducted a prospective randomised crossover study using manikins to investigate whether straddling cardiopulmonary resuscitation improves chest compression quality (depth, recoil, rate, correct hand position) performed on patients during stretcher transportation compared to walking cardiopulmonary resuscitation. Walking and straddling cardiopulmonary resuscitation were performed for 2 minutes each. The mean chest compression depth (mm) for 2 minutes was significantly greater in the straddling cardiopulmonary resuscitation group than in the walking cardiopulmonary resuscitation group (median, 51.3 [interquartile range, 46.7-55.5] versus 40.9 [34.6-50.1], P = 0.003). An adequate depth of chest compressions could not be achieved when walking cardiopulmonary resuscitation was performed by female participants, but the depth of chest compressions was within the acceptable range when female participants performed straddling cardiopulmonary resuscitation. On the other hand, the degree of deterioration was relatively small in male participants, even when they performed walking cardiopulmonary resuscitation. In patients with cardiac arrest being transported on a stretcher, straddling cardiopulmonary resuscitation improved the depth of chest compressions compared to walking cardiopulmonary resuscitation. Female rescuers, in particular, may consider using straddling cardiopulmonary resuscitation.

Histidine augments the suppression of hepatic glucose production by central insulin action.

Glucose intolerance in type 2 diabetes is related to enhanced hepatic glucose production (HGP) due to the increased expression of hepatic gluconeogenic enzymes. Previously, we revealed that hepatic STAT3 decreases the expression of hepatic gluconeogenic enzymes and suppresses HGP. Here, we show that increased plasma histidine results in hepatic STAT3 activation. Intravenous and intracerebroventricular (ICV) administration of histidine-activated hepatic STAT3 reduced G6Pase protein and mRNA levels and augmented HGP suppression by insulin. This suppression of hepatic gluconeogenesis by histidine was abolished by hepatic STAT3 deficiency or hepatic Kupffer cell depletion. Inhibition of HGP by histidine was also blocked by ICV administration of a histamine H1 receptor antagonist. Therefore, histidine activates hepatic STAT3 and suppresses HGP via central histamine action. Hepatic STAT3 phosphorylation after histidine ICV administration was attenuated in histamine H1 receptor knockout (Hrh1KO) mice but not in neuron-specific insulin receptor knockout (NIRKO) mice. Conversely, hepatic STAT3 phosphorylation after insulin ICV administration was attenuated in NIRKO but not in Hrh1KO mice. These findings suggest that central histidine action is independent of central insulin action, while both have additive effects on HGP suppression. Our results indicate that central histidine/histamine-mediated suppression of HGP is a potential target for the treatment of type 2 diabetes.

Single-shot dual-illumination phase unwrapping using a single wavelength.

We propose a single-shot phase unwrapping technique using a single wavelength. In the proposed technique, an object is illuminated by two laser beams, which are emitted from the same laser, whose illumination angles and polarizations are different. Then two types of the object waves generated by the two beams are separately and simultaneously recorded by a polarization imaging camera. We conducted an experiment and a 2.5 mm height object, which was 9400 times height of the wavelength of the laser, was reconstructed without wrapping.

Effect of a dietary supplement containing glucosamine hydrochloride, chondroitin sulfate and quercetin glycosides on symptomatic knee osteoarthritis: a randomized, double-blind, placebo-controlled study.

BACKGROUND: Oral glucosamine and chondroitin sulfate, alone and in combination, have been used worldwide for the treatment of osteoarthritis (OA), but their efficacy is controversial. This clinical study was aimed at investigating the potential of a dietary supplement containing glucosamine and chondroitin sulfate in combination with derivatives of quercetin, a naturally occurring flavonoid, (GCQ supplement) for knee OA care. RESULTS: A randomized, double-blind, placebo-controlled study was conducted in 40 Japanese subjects with symptomatic knee OA. Subjects were randomly assigned to GCQ supplement (1200 mg glucosamine hydrochloride, 60 mg chondroitin sulfate and 45 mg quercetin glycosides per day) or placebo and the treatment and follow-up were continued for 16 weeks. The results of symptomatic efficacy assessment based on Japanese Orthopaedic Association criteria showed that scores for two of the four symptom/function subscales, as well as the aggregate scores, were significantly improved at week 16 or earlier in the GCQ group compared to the placebo group. Moreover, analyses of cartilage metabolism biomarkers showed a trend of improvement in type II collagen synthesis/degradation balance in the GCQ group during follow-up. CONCLUSION: GCQ supplement was thought to be more effective than placebo in decreasing the intensity of knee OA-associated clinical symptoms.

Mechanomyographic responses in human biceps brachii and soleus during sustained isometric contraction.

The purpose of this study was to elucidate the responses of the mechanomyogram (MMG) from two apparently different muscles (biceps brachii and soleus) during a sustained voluntary contraction at 50% maximum voluntary contraction. The MMG and surface electromyogram (EMG) were recorded from human biceps brachii and soleus during sustained elbow flexion and plantar flexion, respectively. Results indicated that the slope coefficient of rise in EMG amplitude as a function of time for the biceps was significantly greater than that for the soleus ( P<0.001). On the contrary, the MMG amplitude of the biceps showed a significant increase during the initial phase of sustained contraction ( P<0.05); however, when exhaustion was approached the amplitude declined significantly ( P<0.05). In the soleus muscle the decrease in MMG amplitude toward exhaustion occurred to a much lesser extent than that observed in the biceps. This difference could be attributed to the nature of the fusion state of the underlying muscle fibers. That is, the great extent of fusion observed in the biceps may be as a result of a greater quantity of fatigable motor units. In addition, the absence of MMG reduction in the soleus would indicate the absence of fatigue-induced slowing of contractile machinery and/or the lack of full activation (tetanus) of muscle fibers even at the exhaustion phase of plantar flexion.

Involvement of noradrenergic system within the central nucleus of the amygdala in naloxone-precipitated morphine withdrawal-induced conditioned place aversion in rats.

RATIONALE: We previously reported that the central nucleus of the amygdala (CeA) plays a crucial role in the negative affective, rather than somatic, component of morphine withdrawal. However, numerous studies have reported that the central ascending noradrenergic system is implicated in morphine withdrawal syndrome, although the roles of the noradrenergic system within the CeA in the negative affective component remains less clear. OBJECTIVES: The possible role of the noradrenergic system within the CeA in the negative affective component of morphine withdrawal was investigated. METHODS: The extracellular noradrenaline level within the CeA during naloxone-precipitated morphine withdrawal was measured using an in vivo microdialysis experiment on unanesthetized and freely moving rats. The effects of microinjection of beta-adrenoceptor antagonists into the bilateral CeA on the naloxone-precipitated morphine withdrawal-induced conditioned place aversion (CPA) and somatic signs were examined. RESULTS: The extracellular noradrenaline level within the CeA was transiently elevated during morphine withdrawal. Intra-CeA injections of beta-adrenoceptor antagonists propranolol (30 nmol per side) and timolol (10 nmol per side) significantly attenuated the morphine withdrawal-induced CPA. Similarly, beta(1)-antagonist atenolol (30 nmol per side) or beta(2)-antagonist butoxamine (30 nmol per side) significantly attenuated the CPA. In contrast, they did not affect morphine withdrawal-induced somatic signs, except for propranolol. CONCLUSION: These results suggest that the activation of the noradrenergic system within the CeA contributes to naloxone-precipitated morphine withdrawal-induced CPA, rather than somatic signs, through beta(1)- and beta(2)-adrenoceptors.

Effects of excitotoxic lesions of the central or basolateral nucleus of the amygdala on naloxone-precipitated withdrawal-induced conditioned place aversion in morphine-dependent rats.

We examined the effects of discrete, bilateral excitotoxic lesions of the central or basolateral nucleus of the amygdala on naloxone-precipitated withdrawal-induced conditioned place aversion in morphine-dependent rats. Lesions of the central nucleus significantly attenuated the conditioned place aversion, while lesions of the basolateral nucleus had little effect. These results suggest that the central nucleus of the amygdala, rather than the basolateral nucleus, plays a crucial role in the negative affective component of morphine abstinence.

Involvement of glutamate receptors within the central nucleus of the amygdala in naloxone-precipitated morphine withdrawal-induced conditioned place aversion in rats.

Chronic use of morphine leads to physical and psychological dependence. The amygdala is known to be involved in the expression of emotion such as anxiety and fear, and several studies have shown that the central nucleus of the amygdala (CeA) is involved in morphine dependence. In the present study, we investigated the role of glutamate receptors within the CeA in the negative affective component of morphine abstinence by evaluating naloxone-precipitated withdrawal-induced conditioned place aversion (CPA) in morphine-dependent rats. We found that microinjection of the AMPA/kainate-glutamate-receptor antagonist CNQX (30 nmol/side) into the bilateral CeA significantly attenuated the naloxone-precipitated withdrawal-induced CPA, as well as several somatic signs, in morphine-dependent rats, without preference or aversive effects by itself in non-dependent rats. Furthermore, microinjection of the non-competitive NMDA-receptor antagonist MK-801 (30 nmol/side) or competitive NMDA-receptor antagonist D-CPPene (0.01 and 0.1 nmol/side) into the CeA significantly attenuated the naloxone-precipitated morphine withdrawal-induced CPA, but not somatic withdrawal signs. These results suggest that the activation of AMPA /kainate and NMDA receptors within the CeA play a crucial role in the negative affective component of morphine abstinence.