Effects of different exercise intensities or durations on salivary IgA secretion

PURPOSE

This study aimed to examine changes in salivary immunoglobulin A (s-IgA) secretion at different intensities or durations of acute exercise.

METHODS

Twelve healthy untrained young males were included in randomized crossover trials in Experiment 1 (cycling exercise for 30 min at a work rate equivalent to 35%, 55%, and 75% maximal oxygen uptake [ V ˙ O2max]) and Experiment 2 (cycling exercise at 55% V ˙ O2max intensity for 30, 60, and 90 min). Saliva samples were collected at baseline, immediately after, and 60 min after each exercise.

RESULTS

Experiment 1: The percentage change in the s-IgA secretion rate in the 75% V ˙ O2max trial was significantly lower than that in the 55% V ˙ O2max trial immediately after exercise (- 45.7%). The percentage change in the salivary concentration of cortisol, an s-IgA regulating factor, immediately after exercise significantly increased compared to that at baseline in the 75% V ˙ O2max trial (+ 107.6%). A significant negative correlation was observed between the percentage changes in saliva flow rate and salivary cortisol concentration (r = - 0.52, P < 0.01). Experiment 2: The percentage change in the s-IgA secretion rate in the 90-min trial was significantly lower than that in the 30-min trial immediately after exercise (-37.0%). However, the percentage change in salivary cortisol concentration remained the same.

CONCLUSION

Our findings suggest that a reduction in s-IgA secretion is induced by exercise intensity of greater than or equal to 75% V ˙ O2max for 30 min or exercise duration of greater than or equal to 90 min at 55% V ˙ O2max in healthy untrained young men.

Maternal age affects pronuclear and chromatin dynamics, morula compaction and cell polarity, and blastulation of human embryos

STUDY QUESTION

Does maternal ageing impact early and late morphokinetic and cellular processes of human blastocyst formation?

SUMMARY ANSWER

Maternal ageing significantly affects pronuclear size and intra- and extra-nuclear dynamics during fertilization, dysregulates cell polarity during compaction, and reduces blastocoel expansion.

WHAT IS KNOWN ALREADY

In ART, advanced maternal age (AMA) affects oocyte yield, fertilization, and overall developmental competence. However, with the exception of chromosome segregation errors occurring during oocyte meiosis, the molecular and biochemical mechanisms responsible for AMA-related subfertility and reduced embryo developmental competence remain unclear. In particular, studies reporting morphokinetics and cellular alterations during the fertilization and pre-implantation period in women of AMA remain limited.

STUDY DESIGN, SIZE, DURATION

A total of 2058 fertilized oocytes were stratified by maternal age according to the Society for Assisted Reproductive Technology classification (<35, 35-37, 38-40, 41-42, and >42 years) and retrospectively analysed. AMA effects were assessed in relation to: embryo morphokinetics and morphological alterations; and the presence and distribution of cell polarity markers-Yes-associated protein (YAP) and protein kinase C-ζ (PKC-ζ)-involved in blastocyst morphogenesis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 1050 cycles from 1050 patients met the inclusion criteria and were analysed. Microinjected oocytes were assessed using a time-lapse culture system. Immature oocytes at oocyte retrieval and mature oocytes not suitable for time-lapse monitoring, owing to an excess of residual corona cells or inadequate orientation for correct observation, were not analysed. Phenomena relevant to meiotic resumption, pronuclear dynamics, cytoplasmic/cortical modifications, cleavage patterns and embryo quality were annotated and compared among groups. Furthermore, 20 human embryos donated for research by consenting couples were used for immunofluorescence.

MAIN RESULTS AND THE ROLE OF CHANCE

Static microscopic observation revealed that blastocyst formation and expansion were impaired in the 41-42 and >42-year groups (P < 0.0001). The morphological grades of the inner cell mass and trophectoderm were poorer in the >42-year group than those in the <35-year group (P = 0.0022 and P < 0.0001, respectively). Time-lapse microscopic observation revealed a reduction in nucleolus precursor body alignment in female pronuclei in the 41-42 and >42-year groups (P = 0.0010). Female pronuclear area decreased and asynchronous pronuclear breakdown increased in the >42-year group (P = 0.0027 and P < 0.0122, respectively). Developmental speed at cleavage stage, incidence of irregularity of first cleavage, type and duration of blastomere movement, and number of multinucleated cells were comparable among age groups. Delayed embryonic compaction and an increased number of extruded blastomeres were observed in the >42-year group (P = 0.0002 and P = 0.0047, respectively). Blastulation and blastocyst expansion were also delayed in the 41-42 and >42-year groups (P < 0.0001 for both). YAP positivity rate in the outer cells of morulae and embryo PKC-ζ immunoflourescence decreased in the >42-year group (P < 0.0001 for both).

LIMITATIONS, REASONS FOR CAUTION

At the cellular level, the investigation was limited to cell polarity markers. Cell components of other developmental pathways should be studied in relation to AMA.

WIDER IMPLICATIONS OF THE FINDINGS

The study indicates that maternal ageing affects the key functions of embryo morphogenesis, irrespective of the well-established influence on the fidelity of oocyte meiosis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the participating institutions. The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Responses of complement C1q/tumor necrosis factor-related proteins to acute aerobic exercise

Aerobic exercise is an effective therapeutic strategy to manage metabolic disorders. However, the mechanisms of aerobic exercise-induced improvements in metabolic diseases are not completely understood. Complement C1q/tumor necrosis factor-related protein (CTRP) 1, CTRP3, CTRP5, and CTRP9 have important roles in improving metabolic disorders via the adenosine monophosphate-activated protein kinase signaling pathway. In this study, we investigated the effects of acute aerobic exercise on circulating CTRP1, CTRP3, CTRP5, and CTRP9 levels in human participants. Eight healthy males with an age of 20.4 ± 0.2 years, height 173.1 ± 1.7 cm, body mass 68.0 ± 1.8 kg, body mass index 22.7 ± 0.7 kg/m², and maximal oxygen uptake (VO₂max) 51.3 ± 2.5 mL/kg/min performed acute aerobic cycling exercise at 75 % of their VO₂max for 30 min (data are mean ± standard error). Blood samples were obtained before; immediately after; and 30, 60, and 120 min after exercising. Serum concentrations of CTRP1, CTRP3, CTRP5, CTRP9, tumor necrosis factor-α (TNF-α), and insulin were measured. The CTRP1 concentration significantly increased immediately after exercising and remained elevated for up to 120 min (p < 0.01). The CTRP3 concentration significantly increased at 60 min after exercise (p < 0.05), and the increasing trend continued until at least 120 min after exercise (p < 0.01). The CTRP5, CTRP9, TNF-α, and insulin concentrations significantly increased immediately after exercise (p < 0.05, p < 0.01, p < 0.05, and p < 0.05, respectively) and decreased thereafter. A significant correlation was observed between the peak post-exercise concentrations of CTRP1 and TNF-α (p < 0.05); however, no correlation was observed between the peak post-exercise concentrations of CTRP3 and insulin. The results of this study indicate that acute aerobic exercise may enhance the secretion of CTRP1, CTRP3, CTRP5, and CTRP9 in healthy adults.

Effects of acute endurance exercise on follistatin-like 1 and apelin in the circulation and metabolic organs in rats

Context: Follistatin-like 1 (FSTL1) and apelin exert a favourable effect on energy metabolism.Objective: We examined the effects of acute endurance exercise on the levels of FSTL1 and apelin in the serum and metabolic organs of rats.Methods: Rats were divided into two groups: a sedentary control (CON, n = 8) group and exercise (EX, n = 8) group. The EX group was made to run on a treadmill at 15-30 m/min for 35 min. Immediately after exercise, the blood, skeletal muscles, adipose, heart, and liver were collected; the levels of FSTL1 and apelin were measured.Results: Serum FSTL1 and apelin were significantly increased following acute exercise; in contrast, the levels of FSTL1 and apelin in the tissues were not affected.Conclusions: Acute endurance exercise may stimulate the secretion of FSTL1 and apelin into the circulation, however, the origin of their increased secreted levels may not be the metabolic organs.

Human 1PN and 3PN zygotes recapitulate all morphokinetic events of normal fertilization but reveal novel developmental errors

STUDY QUESTION

Does mono- (1PN) and tri-pronuclear (3PN) fertilization recapitulate the morphokinetic changes of normal bi-pronuclear (2PN) fertilization?

SUMMARY ANSWER

Abnormal fertilization retraces the overall choreography of normal fertilization but reveals novel morphokinetic phenomena and raises scientifically and clinically relevant questions.

WHAT IS KNOWN ALREADY

ART has allowed the extracorporeal observation of early human development. Time-lapse technology (TLT) has revealed the complexity of the morphokinetic changes underpinning fertilization and the importance of this process for the genetic and cellular integrity of the embryo. Abnormal fertilization has remained neglected, despite its relevance to the physiology and pathology of early human development.

STUDY DESIGN, SIZE, DURATION

This retrospective study involved TLT observation of normally (2PN, N = 2517) and abnormally (1PN, N = 41; 3PN, N = 27) fertilized oocytes generated in ICSI cycles performed between October 2019 and December 2020. Oocyte retrieval was carried out after clomiphene citrate-based minimal ovarian stimulation. Oocytes of patients with different diagnoses of infertility were included in the analysis, while cases involving cryopreserved gametes or surgically retrieved sperm were excluded.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study included 1231 couples treated for diverse infertility causes. The fraction of male factor cases was substantial (36.1%). Microinjected oocytes were assessed by a combined TLT-culture system. Oocytes not suitable for TLT assessment, owing to an excess of residual corona cells or inadequate orientation for correct observation, were not analysed. Phenomena relevant to meiotic resumption, pronuclear dynamics, cytoplasmic/cortical modifications, cleavage patterns and embryo quality were annotated and compared between groups.

MAIN RESULTS AND THE ROLE OF CHANCE

Extrusion of the second polar body (PBII) was observed in almost all 2PN/1PN (99.9% and 100.0%, respectively) and in a vast majority of 3PN zygotes (92.1%). Rates of PBII fusion with the ooplasm were much higher in 1PN and 3PN zygotes (P < 0.0001 versus 2PN). The cytoplasmic wave was observed not only in 2PN and 3PN but also in 1PN zygotes (positivity rates of 99.8% and 100% and 82.9%, respectively; P < 0.0001). More rarely, 2PN and 1PN zygotes emitted a third polar body (PBIII). The average times of this event were comparable. The presence and position of the cytoplasmic halo were comparable among the three classes of zygotes. In the 1PN group, the single PN was maternally or paternally derived in 17 and 24 zygotes, respectively, while in the vast majority of 3PN zygotes (121/127) the supernumerary PN was of maternal origin. Average times of maternal PN appearance were comparable, while average times of paternal PN appearance were delayed in 3PN zygotes (P = 0.0127). Compared with the control group, the area of the maternal PN was larger in 1PN zygotes, but smaller in 3PN zygotes (P < 0.0001). The paternal PNs displayed the same trend (P < 0.0001), although such values were consistently smaller than maternal PNs. The area of the third PN in the 3PN group was on average more than 50% smaller than those of maternal and paternal PNs. In maternal PNs of 3PN zygotes, nucleolus precursor bodies (NPBs) aligned along the area of PN juxtaposition at a lower rate compared with the 2PN group. The rate of NPB alignment was ∼50% smaller in 1PN zygotes (P = 0.0001). In paternal PNs, the rates of NPB alignment were not statistically different among the three groups. Asynchronous PN breakdown was increased in 3PN compared with 2PN zygotes (P = 0.0026). In 1PN zygotes, a developmental delay was observed starting from the disappearance of the cytoplasmic halo, reaching 9 h at the time of the first cleavage (P < 0.0001). Higher rates of abnormal cleavage patterns and blastomere fragmentation (P < 0.0001) were observed in 1PN compared to 2N and 3PN zygotes. Cleavage progression was increasingly affected after abnormal fertilization, especially 1PN, finally resulting in blastocyst formation rates of 70.2%, 12.2% and 53.5% in 2PN, 1PN and 3PN embryos, respectively (P < 0.0001). Both maternal and paternal ages were higher in cases involving 3PN fertilization.

LIMITATIONS, REASONS FOR CAUTION

The study data were obtained from ICSI, but not standard IVF, treatments carried out in a single centre. The study findings therefore require independent verification.

WIDER IMPLICATIONS OF THE FINDINGS

This study reports the first detailed morphokinetic map of human abnormal fertilization. Collectively, this evidence prompts new scientific hypotheses and raises clinical questions relevant to the aetiology and the treatment of abnormal fertilization.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the participating institutions. The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

P-152 The first morphokinetic map of human abnormal fertilisation

Study question

What are the similarities and differences between the morphokinetics of abnormal, one- (1PN) and three-pronuclear (3PN) and normal bi-pronuclear (2PN) fertilisation?

Summary answer

The morphokinetic analysis of 1PN/3PN fertilisation reveals novel aspects of abnormal early development.

What is known already

Assisted reproduction technology has allowed the observation of early human development. Initially assessed statically at a single time point, fertilization has revealed its complexity once observed by Time-Lapse Microscopy (TLM). Detailed morphokinetic analysis of fertilisation has been reported in the last few years, unveiling previously unknown cytoplasmic phenomena (e.g. the cytoplasmic wave and halo) and the importance of cell symmetry for embryo development. At present, abnormal fertilization remains neglected, despite potential for understanding the physiology and pathology of early human development.

Study design, size, duration

This retrospective study involved TLM observation of normally (2PN, n = 2,685) and abnormally (1PN, n = 41; 3PN, n = 127) fertilised oocytes generated in ICSI cycles. Oocyte retrievals were carried out after the clomiphene citrate-based minimal ovarian stimulation, between October 2019 and December 2020. Oocytes of patients with different diagnoses of infertility were included in the analysis, while cases involving cryopreserved gametes or surgically retrieved sperm were excluded.

Participants/materials, setting, methods

Microinjected oocytes were assessed by a combined TLM-culture system (Embryoscope). Oocytes not suitable for TLM assessment, due to excess of residual corona cells or inadequate orientation for correct observation, were not analysed. Phenomena, relevant to meiotic resumption, pronuclear dynamics, cytoplasmic/cortical modifications, cleavage pattern, and embryo quality, were annotated and compared between groups.

Main results and the role of chance

Second polar body (PBII) extrusion was observed in all 1PN- and in a majority of 3PN-zygotes (92.1%). A 0.3-hour delay in PBII extrusion was confirmed in 3PN-zygotes (P = 0.0439). In a significant proportion of 3PN-zygotes, a third (female) PN formed from reabsorption of the PBII. The cytoplasmic wave was observed not only in 2PN- and 3PN-, but also in 1PN-zygotes. The presence and position of cytoplasmic halo were comparable among the three classes of zygotes. However, the duration of the cytoplasmic halo was prolonged in 1PN-zygotes (P &lt; 0.0001). PN juxtaposition immediately before PN breakdown was less frequent in 3PN- compared with 2PN-zygotes (P = 0.0159). Furthermore, asynchronous PN breakdown was increased in 3PN- compared with 2PN-zygotes (P = 0.0026). The PN area of 1PN- was larger than that of 2PN-zygotes; however, the PN area of 3PN-zygotes was smaller than that of 2PN-zygotes. In 1PN-zygotes, a developmental delay was observed starting from the disappearance of the cytoplasmic halo, reaching 9 hours at the time of cleavage (P &lt; 0.0001). A higher incidence of abnormal cleavage (P = 0.0019) and blastomere fragmentation (P &lt; 0.0001) was observed in 1PN-zygotes. Cleavage progression was increasingly affected especially in 1PN-zygotes, resulting in blastocyst formation rates of 70.2%, 12.2% and 53.5% in 2PN-, 1PN- and 3PN-zygotes, respectively (P &lt; 0.0001).

Limitations, reasons for caution

The study data derive from treatments carried out in a single centre. The study findings therefore require independent verification from other research groups.

Wider implications of the findings

These observations suggest that 1PN and 3PN fertilisation follow the general pattern of normal fertilization. Crucially, they also shed light on diverse and previously undescribed phenomena - e.g. reabsorption of the PBII in 3PN zygotes - underpinning the origins of abnormal fertilization and potentially clinically relevant.

Trial registration number

not applicable

Roles of Skeletal Muscle-Derived Exosomes in Organ Metabolic and Immunological Communication

Skeletal muscles secrete various factors, such as proteins/peptides, nucleotides, and metabolites, which are referred to as myokines. Many of these factors are transported into extracellular bodily fluids in a free or protein-bound form. Furthermore, several secretory factors have been shown to be wrapped up by small vesicles, particularly exosomes, secreted into circulation, and subsequently regulate recipient cells. Thus, exosome contents can be recognized as myokines. In recipient cells, proteins, microRNAs, and metabolites in exosomes can regulate the expression and activity of target proteins associated with nutrient metabolism and immune function. The levels of circulating exosomes and their contents are altered in muscle disorders and metabolic-related states, such as metabolic dysfunction, sarcopenia, and physical fitness. Therefore, such circulating factors could mediate various interactions between skeletal muscle and other organs and may be useful as biomarkers reflecting physiological and pathological states associated with muscular function. Here, this review summarizes secretory regulation of muscle-derived exosomes. Their metabolic and immunological roles and the significance of their circulating levels are also discussed.

Secreted protein acidic and rich in cysteine (SPARC) improves glucose tolerance via AMP-activated protein kinase activation

During exercise, skeletal muscles release cytokines, peptides, and metabolites that exert autocrine, paracrine, or endocrine effects on glucose homeostasis. In this study, we investigated the effects of secreted protein acidic and rich in cysteine (SPARC), an exercise-responsive myokine, on glucose metabolism in human and mouse skeletal muscle. SPARC-knockout mice showed impaired systemic metabolism and reduced phosphorylation of AMPK and protein kinase B in skeletal muscle. Treatment of SPARC-knockout mice with recombinant SPARC improved glucose tolerance and concomitantly activated AMPK in skeletal muscle. These effects were dependent on AMPK-γ3 because SPARC treatment enhanced skeletal muscle glucose uptake in wild-type mice but not in AMPK-γ3-knockout mice. SPARC strongly interacted with the voltage-dependent calcium channel, and inhibition of calcium-dependent signaling prevented SPARC-induced AMPK phosphorylation in human and mouse myotubes. Finally, chronic SPARC treatment improved systemic glucose tolerance and AMPK signaling in skeletal muscle of high-fat diet-induced obese mice, highlighting the efficacy of SPARC treatment in the management of metabolic diseases. Thus, our findings suggest that SPARC treatment mimics the effects of exercise on glucose tolerance by enhancing AMPK-dependent glucose uptake in skeletal muscle.-Aoi, W., Hirano, N., Lassiter, D. G., Björnholm, M., Chibalin, A. V., Sakuma, K., Tanimura, Y., Mizushima, K., Takagi, T., Naito, Y., Zierath, J. R., Krook, A. Secreted protein acidic and rich in cysteine (SPARC) improves glucose tolerance via AMP-activated protein kinase activation.

Combined treatment of dipeptidyl peptidase-4 inhibitor and exercise training improves lipid profile in KK/Ta mice

NEW FINDINGS

What is the central question of this study? Exercise for type 2 diabetes patients treated with insulin therapy involves the risk of hypoglycaemia. Dipeptidyl peptidase-4 (DPP-4) inhibitors can be effective in combination with exercise because they reduce the incidence of hypoglycaemia. We evaluated the effect of this combination of treatments on hepatic lipid metabolism in diabetic KK/Ta mice. What is the main finding and its importance? The combination of a DPP-4 inhibitor and exercise, which lowers the risk of hypoglycaemia, is useful for improving insulin resistance by inhibiting excess insulin secretion and decreasing hepatic lipid accumulation, validated by downregulated CD36.

ABSTRACT

The role of exercise training in prevention of diabetes and/or dyslipidaemia has been firmly established. Dipeptidyl peptidase-4 (DPP-4) inhibitors improve insulin sensitivity and have attracted attention as therapeutics for hepatic lipid accumulation. The effect of a combination of DPP-4 inhibitor and exercise training on the prevention and treatment of hepatic lipid accumulation is unclear. Here, we investigated whether alogliptin, a DPP-4 inhibitor, enhances the preventive effect of exercise-induced hepatic lipid accumulation in diabetic mice. Balb/c and KK/Ta mice were fed a high-fat diet. Mice were divided into the following five groups: B, Balb/c mice; K, KK/Ta mice; K-A, KK/Ta mice with alogliptin (0.01%); K-Ex, KK/Ta mice with exercise training (3 days week^-1 , 15-20 m min^-1 for 30 min); and K-Ex+A, KK/Ta mice with alogliptin and exercise training (n = 8 or 9 mice per group). After 8 weeks, glucose, insulin and triglyceride concentrations in the blood and triglyceride levels in the liver were significantly lower in the K-Ex+A group than in the K group. The liver expression level of PPAR-γ in the K group was significantly higher than that in the other groups. Additionally, the liver CD36 expression level was significantly lower in the K-Ex+A and B groups than in the K group. Thus, combined therapy of a DPP-4 inhibitor with exercise training was effective against high-fat diet-induced hepatic lipid accumulation in KK/Ta mice. The results of this study provide useful support for the practice of safe exercise therapy even in diabetic patients who require treatment with a DPP-4 inhibitor.

Effect of dietary antioxidant-rich foods combined with aerobic training on energy metabolism in healthy young men

Although supplementation with several antioxidants has been suggested to improve aerobic metabolism during exercise, whether dietary foods containing such antioxidants can exert the metabolic modulation is unclear. This study aimed to investigate the effect of intake of the specific antioxidant-rich foods coupled with exercise training on energy metabolism. Twenty young healthy, untrained men were assigned to antioxidant and control groups: participants in the antioxidant group were encouraged to consume foods containing catechin, astaxanthin, quercetin, glutathione, and anthocyanin. All participants performed cycle training at 60% maximum oxygen consumption for 30 min, 3 days per week for 4 weeks. Maximum work load was significantly increased by training in both groups, while oxygen consumption during exercise was significantly increased in the antioxidant group only. There were positive correlations between maximum work load and fat/carbohydrate oxidations in the antioxidant group. Carbohydrate oxidation during rest was significantly higher in the post-training than that in the pre-training only in the antioxidant group. More decreased levels of serum insulin and HOMA-IR after training were observed in the antioxidant group than in the control group. This study suggests that specific antioxidant-rich foods could modulate training-induced aerobic metabolism of carbohydrate and fat during rest and exercise.

DEVELOPMENT OF A HIGH-EFFICIENCY PROTON RECOIL TELESCOPE FOR D-T NEUTRON FLUENCE MEASUREMENT

A high-efficiency proton recoil telescope was developed to determine neutron fluences in neutron fields using the 3H(d,n)4He reaction. A 2-mm thick plastic scintillation detector was employed as a radiator to increase the detection efficiency and compensate for the energy loss of the recoil proton within. Two silicon detectors were employed as the ΔE and E detectors. The distance between the radiator and the E detector was varied between 50 and 150 mm. The telescope had detection efficiencies of 3.5 × 10-3 and 7.1 × 10-4 cm2 for distances of 50 and 100 mm, respectively, which were high enough to determine the neutron fluence in 14.8-MeV neutron fields, with a few thousand cm-2 s-1 fluence rate, within a few hours.

Acute exercise increases fibroblast growth factor 21 in metabolic organs and circulation

Fibroblast growth factor 21, a metabolic regulator, plays roles in lipolysis and glucose uptake in adipose tissues and skeletal muscles. Its expression in skeletal muscle is upregulated upon activation of the phosphatidylinositol 3‐kinase/Akt signaling pathway, which is induced by exercise and muscle contraction. We examined the increase of fibroblast growth factor 21 after acute exercise in metabolic organs, especially skeletal muscles and circulation. Participants exercised on bicycle ergometers for 60 min at 75% of their V˙O₂max. Venous blood samples were taken before exercise and immediately after exercise. In an animal study, male ICR mice were divided into sedentary and exercise groups. Mice in the exercise group performed treadmill exercises at 30 m min⁻¹ for 60 min. Shortly thereafter, blood, liver, and skeletal muscle samples were taken from mice. Acute exercise induced the increase of serum fibroblast growth factor 21 in both humans and mice, and increased fibroblast growth factor 21 expression in the skeletal muscles and the liver of mice. Acute exercise activated Akt in mice skeletal muscle. Acute exercise increases fibroblast growth factor 21 concentrations in both serum and metabolic organs. Moreover, results show that acute exercise increased the expression of fibroblast growth factor 21 in skeletal muscle, accompanied by the phosphorylation of Akt in mice.

Salivary extracellular heat shock protein 70 (eHSP70) levels increase after 59 min of intense exercise and correlate with resting salivary secretory immunoglobulin A (SIgA) levels at rest

This study aimed to identify the response of a salivary stress protein, extracellular heat shock protein (eHSP70), to intense exercise and to investigate the relationship between salivary eHSP70 and salivary immunoglobulin A (SIgA) levels in response to exercise. Sixteen healthy sedentary young males (means ± SD 23.8 ± 1.5 years, 172.2 ± 6.4 cm, 68.3 ± 7.4 kg) performed 59 min of cycling exercise at 75% VO2max. Saliva and whole blood samples were collected before (Pre), immediately after (Post), and at 1, 2, 3, and 4 h after completion of the exercise (1, 2, 3, and 4 h). The salivary eHSP70 and SIgA levels were measured by enzyme-linked imunosorbent assay (ELISA), and the secretion rates were computed by multiplying the concentration by the saliva flow rate. White blood cells were analyzed using an automated cell counter with a direct-current detection system. The salivary eHSP70 secretion rates were 1.11 ± 0.86, 1.51 ± 1.47, 1.57 ± 1.32, 2.21 ± 2.04, 3.36 ± 2.72, and 6.89 ± 4.02 ng · min(-1) at Pre, Post, and 1, 2, 3, and 4 h, respectively. The salivary eHSP70 secretion rate was significantly higher at 4 h than that at Pre, Post, 1, and 3 h (p < 0.05). The SIgA secretion rates were 26.9 ± 12.6, 20.3 ± 10.4, 19.6 ± 11.0, 21.8 ± 12.8, 21.5 ± 11.9, and 21.9 ± 11.7 μg · min(-1) at Pre, Post, 1, 2, 3, and 4 h, respectively. The salivary SIgA secretion rate was significantly lower between 1 and 4 h than that at Pre (p < 0.05). There was a positive correlation between salivary eHSP70 and SIgA in both concentration and secretion rates before exercise (p < 0.05). The absolute number of white blood cells significantly increased after exercise, with a maximum at 2 h (p < 0.05). The neutrophil/lymphocyte ratio was significantly increased from 1 to 4 h when compared with that in the Pre samples (p < 0.05). The present study revealed that salivary eHSP70 significantly increased at 4 h after the 59 min of intense exercise in sedentary male subjects. Exercise stress can induce elevated salivary eHSP70 level and upregulate oral immune function partially.

Coenzyme Q10 supplementation downregulates the increase of monocytes expressing toll-like receptor 4 in response to 6-day intensive training in kendo athletes

This study examined changes in toll-like receptor 4 (TLR-4)-expressing monocytes and lymphocyte subpopulations in response to continuous intensive exercise training in athletes, as well as the effect of coenzyme Q10 (CoQ10) supplementation on these changes. Eighteen male elite kendo athletes in Japan were randomly assigned to a CoQ10-supplementation group (n = 9) or a placebo-supplementation group (n = 9) using a double-blind method. Subjects in the CoQ10 group took 300 mg CoQ10 per day for 20 days. Subjects in the placebo group took the same dosage of placebo. All subjects practiced kendo 5.5 h per day for 6 consecutive days during the study period. Blood samples were collected 2 weeks before training, on the first day (day 1), third day (day 3), and fifth day of training (day 5), and 1 week after the training period (post-training) to ascertain TLR-4(+)/CD14(+) monocyte and lymphocyte subpopulations (CD3(+), CD4(+), CD8(+), CD28(+)/CD4(+), CD28(+)/CD8(+), and CD56(+)/CD3(-) cells) using flow cytometry analysis. The group × time interaction for TLR-4(+)/CD14(+) cells did not reach significance (p = 0.08). Within the CoQ10 group, the absolute number of TLR-4(+)/CD14(+) cells was significantly higher only at day 5. The placebo group showed a significant increase in the absolute number of TLR-4(+)/CD14(+) cells at day 3, day 5, and post-training (p < 0.05). There was no significant group × time interaction for any lymphocyte subpopulation. CD3(+), CD8(+), and CD56(+)/CD3(-) cells were significantly reduced at day 3 in both groups (p < 0.05). In conclusion, CoQ10 supplementation might downregulate the increase of TLR-4-expressing monocytes in response to continuous strenuous exercise training in kendo athletes.

Development of portable long counter with two different moderator materials

A portable, light-weight long counter (LC) with small dimensions was developed. This LC consists of a (3)He thermal neutron counter, a cylindrical moderator and outer shields. It was designed to have an almost flat response in a neutron energy range of 0.4 eV to 5 MeV. The portable LC has a radius of 11 cm and a length of 39 cm. Its weight was successfully reduced to 15 kg. Polystyrene was employed instead of polyethylene for the front part of the moderator in order to increase the sensitivity to low-energy neutrons. The response function calculated using the MCNP code was consistent with the results of experiments using monoenergetic neutron calibration fields.

An attempt to decrease anisotropic emissions of neutrons from a cylindrical 241Am-Be-encapsulation source

An attempt to decrease the anisotropic emissions of neutrons from a cylindrical (241)Am-Be-encapsulated X3 source was conducted with Monte Carlo calculations and experiments. The influence of metal materials and shapes of the external casing to the anisotropy factor were focussed on. Results obtained by calculations using MCNP4C implied that a light and spherical-shaped external casing decreases the anisotropic emission of neutrons. Experimental results using the spherical-shaped aluminium protection case also revealed that the anisotropy factor was close to 1.0 with wide zenith angle ranges.

Photon dose mixed in monoenergetic neutron calibration fields using 7Li(p,n)7Be reaction

The ambient dose equivalents H*(10) of photons mixed in the 144, 250 and 565 keV monoenergetic neutron fields were evaluated using measurements from an NaI(Tl) detector and calculations done using the MCNP-ANT code. It was found that H*(10) of the photons produced in the target assembly dominates the dose, particularly near the target. The H*(10) of the photons produced in other materials in the field increases with the increase in distance from the target and could not be neglected at a large distance from the target. The ratios of the H*(10) of the mixed photons to that of the monoenergetic neutrons for 144, 250 and 565 keV neutron fields, were evaluated to be below 5.5, 6.9 and 1.5 %, respectively. The ratios were calculated at calibration points between 100 and 500 cm from the target.

The astaxanthin-induced improvement in lipid metabolism during exercise is mediated by a PGC-1α increase in skeletal muscle

Astaxanthin, a xanthophyll carotenoid, accelerates lipid utilization during aerobic exercise, although the underlying mechanism is unclear. The present study investigated the effect of astaxanthin intake on lipid metabolism associated with peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) in mice. Mice were divided into 4 groups: sedentary, sedentary and astaxanthin-treated, exercised, and exercised and astaxanthin-treated. After 2 weeks of treatment, the exercise groups performed treadmill running at 25 m/min for 30 min. Immediately after running, intermuscular pH was measured in hind limb muscles, and blood was collected for measurements. Proteins were extracted from the muscle samples and PGC-1α and its downstream proteins were measured by western blotting. Levels of plasma fatty acids were significantly decreased after exercise in the astaxanthin-fed mice compared with those fed a normal diet. Intermuscular pH was significantly decreased by exercise, and this decrease was inhibited by intake of astaxanthin. Levels of PGC-1α and its downstream proteins were significantly elevated in astaxanthin-fed mice compared with mice fed a normal diet. Astaxanthin intake resulted in a PGC-1α elevation in skeletal muscle, which can lead to acceleration of lipid utilization through activation of mitochondrial aerobic metabolism.

Preventive effect of agaro-oligosaccharides on non-steroidal anti-inflammatory drug-induced small intestinal injury in mice

BACKGROUND AND AIM

Non-steroidal anti-inflammatory drugs (NSAIDs), which are commonly used in clinical medicine, cause erosion, ulcers, and bleeding in the gastrointestinal tract. No effective agent for the prevention and treatment of small intestinal injury by NSAIDs has been established. This study investigates the effects of agaro-oligosaccharides (AGOs) on NSAID-induced small intestinal injury in mice.

METHODS

Mice were treated with indomethacin, an NSAID, to induce intestinal injury. The respective degrees of mucosal injury of mice that received AGO and control mice were compared. Heme oxygenase-1 (HO-1) expression using quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting, and immunohistochemistry were measured. The expression of keratinocyte chemoattractant (KC) was measured using qRT-PCR and enzyme-linked immunosorbent assay.

RESULTS

AGO administration induced HO-1 expression in mouse small intestinal mucosa. Induction was observed mainly in F4/80 positive macrophages. The increased ulcers score, myeloperoxidase activity, and KC expression by indomethacin were inhibited by AGO administration. Conversely, HO inhibitor cancelled AGO-mediated prevention of intestinal injury. In mouse peritoneal macrophages, AGOs enhanced HO-1 expression and suppressed lipopolysaccharide-induced KC expression. Furthermore, AGOs enhanced the expressions of alternatively activated macrophage markers arginase-1, mannose receptor-1, and chitinase 3-like 3.

CONCLUSIONS

Results suggest that oral administration of AGOs prevents NSAID-induced intestinal injury.

A novel myokine, secreted protein acidic and rich in cysteine (SPARC), suppresses colon tumorigenesis via regular exercise

OBJECTIVE

Several epidemiological studies have shown that regular exercise can prevent the onset of colon cancer, although the underlying mechanism is unclear. Myokines are secreted skeletal muscle proteins responsible for some exercise-induced health benefits including metabolic improvement and anti-inflammatory effects in organs. The purpose of this study was to identify new myokines that contribute to the prevention of colon tumorigenesis.

METHODS

To identify novel secreted muscle-derived proteins, DNA microarrays were used to compare the transcriptome of muscle tissue in sedentary and exercised young and old mice. The level of circulating secreted protein acidic and rich in cysteine (SPARC) was measured in mice and humans that performed a single bout of exercise. The effect of SPARC on colon tumorigenesis was examined using SPARC-null mice. The secretion and function of SPARC was examined in culture experiments.

RESULTS

A single bout of exercise increased the expression and secretion of SPARC in skeletal muscle in both mice and humans. In addition, in an azoxymethane-induced colon cancer mouse model, regular low-intensity exercise significantly reduced the formation of aberrant crypt foci in wild-type mice but not in SPARC-null mice. Furthermore, regular exercise enhanced apoptosis in colon mucosal cells and increased the cleaved forms of caspase-3 and caspase-8 in wild-type mice but not in SPARC-null mice. Culture experiments showed that SPARC secretion from myocytes was induced by cyclic stretch and inhibited proliferation with apoptotic effect of colon cancer cells.

CONCLUSIONS

These findings suggest that exercise stimulates SPARC secretion from muscle tissues and that SPARC inhibits colon tumorigenesis by increasing apoptosis.

Muscle-enriched microRNA miR-486 decreases in circulation in response to exercise in young men

Background: MicroRNAs (miRNAs) are small non-coding RNAs involved in post-transcriptional gene regulation. miRNAs are taken in by intracellular exosomes, secreted into circulation, and taken up by other cells, where they regulate cellular functions. We hypothesized that muscle-enriched miRNAs existing in circulation mediate beneficial metabolic responses induced by exercise. To test this hypothesis, we measured changes in muscle-enriched circulating miRNAs (c-miRNAs) in response to acute and chronic aerobic exercise.

Methods: Eleven healthy young men (age, 21.5 ± 4.5 y; height, 168.6 ± 5.3 cm; and body weight, 62.5 ± 9.0 kg) performed a single bout of steady-state cycling exercise at 70% VO_2max for 60 min (acute exercise) and cycling training 3 days per week for 4 weeks (chronic exercise). Blood samples were collected from the antecubital vein before and after acute and chronic exercise. RNA was extracted from serum, and the levels of muscle-enriched miRNAs (miR-1, miR-133a, miR-133b, miR-206, miR-208b, miR-486, and miR-499) were measured.

Results: All of these miRNAs, except for miR-486, were found at too low copy numbers at baseline to be compared. miR-486 was significantly decreased by both acute (P = 0.013) and chronic exercise (P = 0.014). In addition, the change ratio of miR-486 due to acute exercise showed a significant negative correlation with VO_2max for each subject (R = 0.58, P = 0.038).

Conclusion: The reduction in circulating miR-486 may be associated with metabolic changes during exercise and adaptation induced by training.

Exercise-induced muscle damage impairs insulin signaling pathway associated with IRS-1 oxidative modification

Strenuous exercise induces delayed-onset muscle damage including oxidative damage of cellular components. Oxidative stress to muscle cells impairs glucose uptake via disturbance of insulin signaling pathway. We investigated glucose uptake and insulin signaling in relation to oxidative protein modification in muscle after acute strenuous exercise. ICR mice were divided into sedentary and exercise groups. Mice in the exercise group performed downhill running exercise at 30 m/min for 30 min. At 24 hr after exercise, metabolic performance and insulin-signaling proteins in muscle tissues were examined. In whole body indirect calorimetry, carbohydrate utilization was decreased in the exercised mice along with reduction of the respiratory exchange ratio compared to the rested control mice. Insulin-stimulated uptake of 2-deoxy-[(3)H]glucose in damaged muscle was decreased after acute exercise. Tyrosine phosphorylation of insulin receptor substrate (IRS)-1 and phosphatidyl-3-kinase/Akt signaling were impaired by exercise, leading to inhibition of the membrane translocation of glucose transporter 4. We also found that acute exercise caused 4-hydroxy-nonenal modification of IRS-1 along with elevation of oxidative stress in muscle tissue. Impairment of insulin-induced glucose uptake into damaged muscle after strenuous exercise would be related to disturbance of insulin signal transduction by oxidative modification of IRS-1.

Heat shock protein 70-dependent protective effect of polaprezinc on acetylsalicylic acid-induced apoptosis of rat intestinal epithelial cells

Protection of the small intestine from mucosal injury induced by nonsteroidal anti-inflammatory drugs including acetylsalicylic acid is a critical issue in the field of gastroenterology. Polaprezinc an anti-ulcer drug, consisting of zinc and L-carnosine, provides gastric mucosal protection against various irritants. In this study, we investigated the protective effect of polaprezinc on acetylsalicylic acid-induced apoptosis of the RIE1 rat intestinal epithelial cell line. Confluent rat intestinal epithelial cells were incubated with 70 µM polaprezinc for 24 h, and then stimulated with or without 15 mM acetylsalicylic acid for a further 15 h. Subsequent cellular viability was quantified by fluorometric assay based on cell lysis and staining. Acetylsalicylic acid-induced cell death was also qualified by fluorescent microscopy of Hoechst33342 and propidium iodide. Heat shock proteins 70 protein expression after adding polaprezinc or acetylsalicylic acid was assessed by western blotting. To investigate the role of Heat shock protein 70, Heat shock protein 70-specific small interfering RNA was applied. Cell viability was quantified by fluorometric assay based on cell lysis and staining and apoptosis was analyzed by fluorescence-activated cell sorting. We found that acetylsalicylic acid significantly induced apoptosis of rat intestinal epithelial cells in a dose- and time-dependent manner. Polaprezinc significantly suppressed acetylsalicylic acid-induced apoptosis of rat intestinal epithelial cells at its late phase. At the same time, polaprezinc increased Heat shock protein 70 expressions of rat intestinal epithelial cells in a time-dependent manner. However, in Heat shock protein 70-silenced rat intestinal epithelial cells, polaprezinc could not suppress acetylsalicylic acid -induced apoptosis at its late phase. We conclude that polaprezinc-increased Heat shock protein 70 expression might be an important mechanism by which polaprezinc suppresses acetylsalicylic acid-induced small intestinal apoptosis, a hallmark of acetylsalicylic acid-induced enteropathy.

Regular exercise reduces colon tumorigenesis associated with suppression of iNOS

Several epidemiological studies have shown that regular exercise can prevent the onset of colon cancer, although the mechanism involved is unclear. Expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) is often elevated in an initial step of tumorigenesis and promotes colorectal cancer. We investigated the effect of exercise on colon tumorigenesis associated with iNOS and COX-2 in azoxymethan (AOM)-injected mice. Balb/c mice (8 weeks old) were divided into three groups of 20 animals each, consisting of a sedentary control group, an AOM group, and an exercise plus AOM group. Mice in the groups receiving AOM were injected intraperitoneally with AOM weekly for 2 weeks. Six weeks of regular exercise suppressed the generation of aberrant crypt foci (ACF) in the colon by AOM. Expression of iNOS was decreased by exercise compared with that in sedentary mice along with lower nitrotyrosine level while COX-2 was not changed by either AOM or exercise. Additionally, tumor necrosis factor alpha (TNFalpha) was decreased by exercise in the colon and plasma. There was no effect of exercise on the expression of antioxidant enzymes and chaperon protein in the colon. Our results suggest that regular exercise prevents colon tumorigenesis, at least partly via the suppression of iNOS expression associated with anti-inflammation.

Effect of Acupuncture on Salivary Immunoglobulin a after a Bout of Intense Exercise

In the field of athletics, acupuncture has been used for treatment of injury, reduction of fatigue and management of physical condition. However, there is little information on the effect of acupuncture on the immune function in response to exercise.

Purpose

The aim of this study was to examine the effect of acupuncture treatment on the mucosal immune function after a single period of intense exercise by measuring salivary immunoglobulin A (SIgA).

Methods

12 healthy men (23.6±SEv 0.3 years) participated in this study with a crossover design. The subjects exercised on a bicycle equipped with an ergometer at 75% VO2max for 60 min. Acupuncture treatment was applied at LU6, LI4, ST36 and ST6, for 30 min after the exercise. The control treatment was rest without acupuncture and that the order of the treatment was randomised. We measured parameters including saliva flow rate, SIgA concentration, SIgA secretion rate, heart rate and plasma catecholamine concentration all before the exercise and at 1 h, 2 h, 3 h, 4 h and 24 h after the exercise. The visual analogue scale for self-perceived tiredness and the profile of mood states questionnaires were recorded before the exercise and at 24 h after the exercise.

Result

Intense exercise-induced decrease of SIgA levels was attenuated by the acupuncture treatment. In contrast, the subjective fatigue score and psychological measurement were not affected by the acupuncture.

Conclusion

Acupuncture treatment may attenuate the decrease in SIgA level induced by intense exercise.

Effect of 6-day intense Kendo training on lymphocyte counts and its expression of CD95

This study examines the effects of 6-day intensive training on lymphocyte counts and their expression of CD95. Eight healthy Kendo athletes underwent 6-day Kendo training of about 310 min each day. Blood samples were collected at 2 weeks before (PRE), the first day (Day 1), third day (Day 3), fifth day (Day 5), and 1 week after the training period (POST) to determine lymphocyte counts and CD95 expression on CD95 lymphocytes (CD4(+), CD8(+)) using flow cytometry. The total lymphocyte counts were significantly lower at Day 3 than at PRE. The CD8(+) cell counts were significantly lower at Day 3 than at PRE. The percentage of CD95(+) lymphocytes was significantly higher at Day 1 and Day 3 than at PRE. The percentage of CD8(+)CD95(+) cells did not change significantly. The total lymphocyte counts decreased and a concomitant increase of CD95(+) lymphocyte was observed, whereas the decrease in CD8(+) cell counts was not associated with the increase in CD8(+)CD95(+) cells. Therefore, short-term high-intensity exercise induced a decrease in the T lymphocyte counts without increasing in CD95(+) expression.

Exercise-induced oxidative DNA damage and lymphocytopenia in sedentary young males

Post high-intensity exercise lymphocytopenia is well documented, but its underlying mechanisms have not been fully elucidated. A possible mechanism is a reactive oxygen species-induced DNA damage after high-intensity exercise. Furthermore, lymphocyte apoptosis related to DNA damage might contribute to exercise-induced lymphocytopenia.

PURPOSE

This study examined lymphocytopenia, lymphocyte oxidative DNA damage, and apoptosis in young healthy sedentary males after acute high-intensity exercise.

METHOD

Fifteen subjects exercised on bicycle ergometers for 1 h at 75% of their VO2max. Venous blood samples were taken before exercise (PRE) and hourly after exercise until 4 h (P0-P4). Lymphocyte counts, oxidative DNA damage evaluated using the Comet assay with human 8-oxoguanine DNA glycosylase, and serum lipid peroxide (LPO) concentration were measured. Furthermore, lymphocyte superoxide, Fas receptor (CD95), and Annexin-V-positive lymphocyte apoptosis cells were measured in 10 subjects who exercised and gave blood samples as described above.

RESULTS

Lymphocyte counts became significantly lower than the PRE value (P < 0.05): 20.4% at P1, 24.3% at P2, and 16.3% at P3. Moreover, LPO significantly increased by P2 (P < 0.05): 1.6-fold. The % DNA in tail, indicating oxidative DNA damage, was significantly higher at P3 (54.3 +/- 12.8%) than at PRE (42.6 +/- 11.1%, P < 0.05). The lymphocyte superoxide level was significantly higher (51.3%) than the PRE value (P < 0.05). Neither CD95 nor Annexin-V-positive cells were significantly different than the PRE value.

CONCLUSION

Results of this study suggest that lymphocyte oxidative DNA damage can relate to lymphocytopenia, although DNA damage was not associated with apoptosis in healthy young sedentary males.

Systemic arterial compliance, systemic vascular resistance, and effective arterial elastance during exercise in endurance-trained men

Systemic arterial compliance (C) and vascular resistance (R) regulate effective arterial elastance (Ea), an index of artery load. Increases in Ea during exercise are due primarily to reductions of C and maintain optimal ventricular-arterial coupling. Because C at rest and left ventricular functional reserve are greater in endurance-trained (ET) compared with sedentary control (SC) humans, we hypothesized that reductions of C and increases in Ea are greater in ET than SC individuals. The aim of this study was to investigate C, R, and Ea during exercise in ET and SC humans. C, R, Ea, and cardiac cycle length (T) were measured at rest and during exercise of 40, 60, and 80% maximal oxygen uptake using Doppler ultrasonography in 12 SC and 13 ET men. C decreased in an exercise intensity-dependent manner in both groups, but its reductions were greater in the ET than SC subjects. Consequently, although C at rest was greater in the ET than SC group, the intergroup difference in C disappeared during exercise. Exercise-related changes in R/T were relatively slight and R/T was lower in the ET than the SC group, both at rest and during exercise. Although Ea at rest was lower in the ET than SC group, there were no intergroup differences in Ea at 40, 60, or 80% maximal oxygen uptake. We conclude that the reductions of C from rest to exercise are more marked in ET than SC humans. This may be related to the exercise-associated disappearance of the difference in Ea between ET and SC humans.

Relationship between arterial stiffness and athletic training programs in young adult men

BACKGROUND

We examined the relationships of endurance and strength exercise training and the adolescent duration of training to arterial stiffness in young adult men. We hypothesized that young adults participating in endurance sports would have decreased arterial stiffness, whereas those in strength-based sports would have increased arterial stiffness. In addition, we predicted that these trends would be more pronounced with an increase in the duration of sport participation.

METHODS

Subjects were male endurance-trained men with short (current age, 20 years; age at beginning of competitive sport, 15 years; sport careers, 5 years; n = 7, S-ET) and long (current age, 20 years; age at beginning of competitive sport, 12 years; sport careers, 8 years; n = 7, L-ET) competitive sport careers, strength-trained men with short (current age, 20 years; age at beginning of competitive sport, 16 years; sport careers, 4 years; n = 7, S-ST) and long (current age, 22 years; age at beginning of competitive sport, 15 years; sport careers, 7 years; n = 7, L-ST) careers, and sedentary control men (aged, 20 years; n = 7, C).

RESULTS

The exercise training was associated with aortic pulse wave velocity (PWV), a traditional index of arterial stiffness, and the associations were statistically independent of blood pressure (BP). Aortic PWV was lower in L-ET than C and ST. Aortic PWV in L-ST was greater than that of C. The associations of exercise training with systemic arterial compliance (SAC), which inversely correlates with arterial stiffness, were also positive and BP independent. The SAC was greater in the ET groups compared with C and ST groups. The SAC in L-ST was lower than in C.

CONCLUSIONS

These results suggest that changes in arterial stiffness associated with different training programs appear in young adults as well as in older humans, and these changes may begin in adolescence.

Postexercise Heart Rate Recovery Accelerates in Strength-Trained Athletes

The left ventricle morphologically adapts to endurance exercise training (eccentric cardiac remodeling) and strength exercise training (concentric remodeling). In addition, the acceleration of vagally mediated heart rate (HR) recovery after exercise is one of the functional adaptations of the heart in endurance-trained humans. However, the effect of strength training on HR recovery is unclear.

PURPOSE

The purpose of this study was to investigate whether postexercise HR recovery accelerates in strength-trained athletes.

METHODS

Subjects were young strength-trained athletes (ST; N = 12), endurance-trained athletes (ET; N = 12), and age-matched sedentary control men (C; N = 12). HR and oxygen uptake were measured during submaximal exercise (cycling exercise, 40% maximal oxygen uptake for 8 min) and 30 s after the exercise (the postexercise period).

RESULTS

Left ventricular end-diastolic dimension was higher in both types of athletes compared with C, but greater in ET than in ST (C, 4.3 +/- 0.1 cm; ET, 5.0 +/- 0.1 cm; ST, 4.8 +/- 0.1 cm). Left ventricular average wall thickness was greater in ST in comparison with ET, although it was higher in both trained men compared with C (C, 0.85 +/- 0.02 cm; ET, 0.90 +/- 0.02 cm; ST, 1.00 +/- 0.02 cm). The time constant of postexercise HR decay, an index of vagally mediated postexercise HR recovery, was lower in ST and ET compared with C (C, 94.4 +/- 9.2 s; ET, 65.9 +/- 4.3 s; ST, 69.1 +/- 4.0 s). Oxygen pulse was greater in ST and ET than in C (C, 9.4 +/- 0.6 mL per beat; ET, 13.0 +/- 0.9 mL per beat; ST, 12.8 +/- 0.4 mL per beat), and it results in increased oxygen debt for both types of athletes (C, 0.257 +/- 0.024 L; ET, 0.343 +/- 0.030 L; ST, 0.331 +/- 0.017 L). We did not find significant differences in these indices between ST and ET.

CONCLUSIONS

These results suggest that the HR recovery immediately after exercise is accelerated in both strength- and endurance-trained athletes.

Construction of monoenergetic neutron calibration fields using 45Sc(p, n)45Ti reaction at JAEA

The 8 and 27 keV monoenergetic neutron calibration fields have been developed by using (45)Sc(p, n)(45)Ti reaction. Protons from a 4-MV Pelletron accelerator are used to bombard a thin scandium target evaporated onto a platinum disc. The proton energies are finely adjusted to the resonance to generate the 8 and 27 keV neutrons by applying a high voltage to the target assemblies. The neutron energies were measured using the time-of-flight method with a lithium glass scintillation detector. The neutron fluences at a calibration point located at 50 cm from the target were evaluated using Bonner spheres. A long counter was placed at 2.2 m from the target and at 60 degrees to the direction of the proton beam in order to monitor the fluence at the calibration point. Fluence and dose equivalent rates at the calibration point are sufficient to calibrate many types of the neutron survey metres.

Investigation of properties of the TIARA neutron beam facility of importance for calibration applications

Evaluation of the properties for quasi-monoenergetic neutron calibration fields of high energies more than 20 MeV at TIARA is proceeding for development of the field. Among the properties needed for the development as the standard calibration field, we report on measurement of the neutron beam profile using an imaging plate with a polyethylene converter and on estimation of the contribution of scattered neutrons into the irradiation field based on pulse height distribution at various off-beam positions measured using an organic liquid scintillation detector.

Vascular endothelium-derived factors and arterial stiffness in strength- and endurance-trained men

Arterial stiffness is higher in strength-trained humans and lower in endurance-trained humans. However, the mechanisms underlying these different adaptations are unclear. Vascular endothelium-derived factors, such as endothelin-1 (ET-1) and nitric oxide (NO), play an important role in the regulation of vascular tonus. We hypothesized that endogenous ET-1 and NO participate in the adaptation of arterial stiffness in different types of exercise training. The purpose of this study was to investigate plasma ET-1 and NO concentrations and arterial stiffness in strength- and endurance-trained men. Young strength-trained athletes (SA; n = 11), endurance-trained athletes (EA; n = 12), and sedentary control men (C; n = 12) participated in this study. Maximal handgrip strength in SA and maximal oxygen uptake in EA were markedly greater than in C. Aortic pulse-wave velocity, which is an established index of arterial stiffness, was higher in SA and lower in EA than in C. Additionally, we measured systemic arterial compliance (SAC) using carotid artery applanation tonometry and Doppler echocardiography, because arterial stiffness is a primary determinant of the compliance. SAC was lower in SA and higher in EA compared with that in C. Plasma ET-1 concentrations were higher in SA compared with C and EA. We did not find significant differences in plasma NO concentrations (measured as the stable end product of NO, i.e., nitrite/nitrate). The relationships of plasma ET-1 concentrations to aortic pulse-wave velocity and SAC were linear. These results suggest that differences in endogenous ET-1 may partly participate in the mechanism underlying different adaptations of arterial stiffness in strength- and endurance-trained men.

Contribution of systemic arterial compliance and systemic vascular resistance to effective arterial elastance changes during exercise in humans

BACKGROUND

Effective arterial elastance (Ea), an index of arterial load, increases with elevations in left ventricular elastance to maximize the efficiency of left ventricular stroke work during exercise. Systemic arterial compliance (C) and vascular resistance (R) are the primary components contributing to Ea, and R plays a greater role in determining Ea at rest. We hypothesized that the contribution of C to Ea increases during exercise to maintain an optimal balance between arterial load and ventricular elastance, and that the increase in Ea is due primarily to a reduction in C.

AIM

The aim of this study was to investigate the contributions of C and R to Ea during exercise.

METHODS

Ea (0.9 x systolic blood pressure/stroke volume), C (stroke volume/pulse pressure), R (mean blood pressure/cardiac output), and cardiac cycle length (T) were measured at rest and during exercise of 40%, 60% and 80% maximal oxygen uptake (O(2max)) using Doppler echocardiography in 45 healthy men.

RESULTS

Ea did not differ between rest and 40%O(2max), but it was greater at 60% and 80%O(2max). C markedly decreased during exercise in an exercise intensity-dependent manner. The changes in R/T during exercise were small, whereas it decreased at 40%O(2max) and gradually increased at 60% and 80%O(2max).

CONCLUSIONS

The present results suggest that the contribution of systemic arterial compliance to effective arterial elastance increases during exercise. Therefore, we propose that the increase in arterial load during exercise is mainly driven by a reduction in systemic arterial compliance.

Effects of athletic strength and endurance exercise training in young humans on plasma endothelin-1 concentration and arterial distensibility

Strength exercise training induces a decrease in arterial distensibility, whereas endurance exercise training causes an increase in arterial distensibility. Endothelin-1 (ET-1), which is produced by vascular endothelial cells, has potent vasoconstrictor and proliferative activity on vascular smooth muscle cells. We hypothesized that endogenous ET-1 participates in alteration of arterial distensibility by different exercise training types (i.e., strength and endurance exercise training). The purpose of the present study was to investigate plasma ET-1 concentration and arterial distensibility in strength- and endurance-trained athletes. Subjects were male strength-trained athletes (discus, hammer, or javelin throwers; 22.2 years; SA), male endurance-trained athletes (long- or middle-distance runners; 20.7 years; EA), and sedentary healthy men (20.6 years; sedentary control, SC). Maximum hand-grip strength was markedly greater in SA compared with EA and SC (55.3 vs. 41.1 vs. 40.5 kg, P < 0.05). Maximum oxygen uptake was markedly greater in EA than in SA and SC (60.9 vs. 43.1 vs. 43.6 ml/kg/min, P < 0.05). Arterial pulse wave velocity (PWV), which is an index of arterial distensibility, was significantly higher in SA than in EA and SC (688 vs. 529 vs. 601 cm/sec, P < 0.05). In EA, PWV was significantly lower in comparison to that in SC (P < 0.05). Thus arterial distensibility was lower in SA than in EA and SC and higher in EA than in SC. Plasma ET-1 concentration was significantly higher in SA compared with EA and SC (1.64 vs. 1.12 vs. 1.24 pg/ml, P < 0.05). Plasma ET-1 concentration tended to be lower in EA than in SC. These results suggest that the difference in plasma ET-1 level may participate in the mechanism underlying different adaptation of arterial distensibility between strength- and endurance-trained athletes.

Conceptual design of spectrum changeable neutron calibration fields in JAERI/FRS

Spectrum changeable neutron calibration fields are planned to be established with an accelerator installed in Japan Atomic Energy Research Institute/Facility of Radiation Standards. The neutron fields are provided by bombarding a target surrounded by a moderator, with charged particles from the accelerator. In the fields, a wide variety of neutron spectra is provided with sufficient fluence rate for the calibration of dosemeters. In this study, necessity of the field was first discussed in view of relationship between readings of existing dosemeters and true dose equivalents where the dosemeters were used. Second, test simulation of neutron spectra was carried out with the Monte Carlo technique for some arrangements with a LiF target and quasi-cylindrical moderators with different materials. The simulated spectra were summarised in terms of fluence-average energy, fluence rate and calibration factor for the dosemeters.

Neutron spectra and angular distributions of concrete-moderated neutron calibration fields at JAERI

The Facility of Radiation Standards of Japan Atomic Energy Research Institute has been equipped with concrete-moderated neutron calibration fields as simulated workplace neutron fields. The fields use an 241Am-Be neutron source placed in the narrow space surrounded by concrete bricks, walls and floor. The neutron spectra and the neutron fluence rates of the fields were measured with the Bonner multi-sphere spectrometer system (BMS), spherical recoil-proton proportional counters, and a liquid scintillation counter (NE-213). The results were compared with each other. The reference values of H*(10) were determined from the results of BMS. The angular distributions of neutron fluence were calculated using MCNP-4B2 to obtain the reference values of Hp(10). The calculated results show that the scattered neutrons have a wide range of incident angles. The reference Hp(10) values considered the angular distribution were found to be 10-18% smaller than those without consideration.

Construction of 144, 565 keV and 5.0 MeV monoenergetic neutron calibration fields at JAERI

Monoenergetic neutron calibration fields of 144, 565 keV and 5.0 MeV have been developed at the Facility of Radiation Standards of JAERI using a 4 MV Pelletron accelerator. The 7Li(p,n)7Be and 2H(d,n)3He reactions are employed for neutron production. The neutron energy was measured by the time-of-flight method with a liquid scintillation detector and calculated with the MCNP-ANT code. A long counter is employed as a neutron monitor because of the flat response. The monitor is set up where the influence of inscattered neutrons from devices and their supporting materials at a calibration point is as small as possible. The calibration coefficients from the monitor counts to the neutron fluence at a calibration point were obtained from the reference fluence measured with the transfer instrument of the primary standard laboratory (AIST), a 24.13 cm phi Bonner sphere counter. The traceability of the fields to AIST was established through the calibration.