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Objective: Diminished physical capacity is common and progressive in patients undergoing dialysis, who are also prone to deficiency in carnitine, which plays a pivotal role in maintaining skeletal muscle and cardiac function. The present study aimed to evaluate the association of carnitine profile with exercise parameters in patients with incident dialysis. Design and Methods: This was a single-center cross-sectional study including 87 consecutive patients aged 20-90 years who were initiated on dialysis in Keio University Hospital between December 2019 and December 2022 and fulfilled the eligibility criteria. Exercise parameters were evaluated via cardiopulmonary testing (CPX) using the electronically braked STRENGTH ERGO 8 ergometer, whereas the carnitine profile was assessed by determining serum free carnitine (FC), acylcarnitine (AC) levels and AC/FC ratio. Results: The mean cohort age was 62.1 ± 15.2 years, with male and hemodialysis predominance (70% and 73%, respectively). AC/FC was 0.46 ± 0.15, and CPX revealed peak oxygen consumption (VO2) of 13.9 ± 3.7 (mL/kg/min) with percentpredicted peak VO2 of 53.6% ± 14.7% and minute ventilation (VE)/carbon dioxide output (VCO2) slope of 35.1 ± 8.0. Fully-adjusted multivariate linear regression analysis showed that AC/FC was significantly associated with decreased peak VO2 (β, -5.43 [95% confidence interval (CI), -10.15 to -0.70]) and percent-predicted peak VO2 (β, -19.98 [95% CI, -38.43 to -1.52]) and with increased VE/VCO2 slope (β, 13.76 [95% CI, 3.78-23.75]); FC and AC did not exhibit similar associations with these parameters. Moreover, only AC/FC was associated with a decreased peak work rate (WR), percent-predicted WR, anaerobic threshold, delta VO2/delta WR, and chronotropic index. Conclusion: In patients on incident dialysis, exercise parameters, including those related to both skeletal muscle and cardiac function, were strongly associated with AC/FC, a marker of carnitine deficiency indicating altered fatty acid metabolism. Further studies are warranted to determine whether carnitine supplementation can improve exercise capacity in patients on incident dialysis. [ABSTRACT FROM AUTHOR]

The mechanism causing high-frequency combustion instability was presumed to be the progression of combustion at an off-design location; that is, in the vicinity of the faceplate. Experiments were carried out to prove this. In the experiments, water was used to simulate the propellant and the increase in pressure caused by off-design combustion was simulated by injecting nitrogen gas. Pressure increase and decay were measured to within approximately 1 ms, and the maximum local pressure was approximately twice the pressure prior to increasing the pressure. To estimate the pressure change in actual engines, a simplified simulation calculation model was constructed. After calibration using the experimental results, the time and amplitude of pressure change were on the same order of magnitude of those of the engines. The present study results show that the off-design combustion model can be a cause of the high-frequency combustion instability experienced when using liquid rocket engines. [ABSTRACT FROM AUTHOR]

A newly constructed model calculates the starting position of the pseudo-shock, or shock train, in the divergent ducts. The model is based on the conservation laws of mass, energy and momentum of the inflow and outflow into/from the pseudo-shock region, and further uses a sonic condition in the core flow of the pseudo-shock. The model adopts an empirical growth rate of the low-velocity region, and the divergent angle of the nozzles becomes a design parameter. The lengths of the pseudo-shocks calculated show reasonable agreement with the experimental results. Pressure distribution with quick increase near the starting position is simulated. The supersonic core flow cross-section becomes smaller than that at the starting position of the pseudo-shock. The pressure at the sonic point rises to 0.7 of that at the duct exit. The length of the quick pressure-increase region becomes longer as the Mach number increases at the starting position. [ABSTRACT FROM AUTHOR]

Numerical simulation of aerodynamics around the spaceplane was conducted in the equivalent condition to the transonic wind tunnel tests at ISAS/JAXA. Numerical results reproduced experimental results, and they are useful to discuss the experimental results. Two configurations, namely, the experimental model and the original model were investigated. In all Mach numbers, drag coefficient of the experimental model was larger than that of the original model. Especially the wing and the tail made large drag. The different cross section of the wing and the tail caused the larger drag in the experimental model. [ABSTRACT FROM AUTHOR]

This paper describes the characteristics of methane-fueled rocket engines and compares these characteristics with those of hydrogen-fueled engines in terms of both expander and coolant-bleed cycles. Methane vaporizes in a cooling jacket under low-pressure operating conditions, whereas it liquefies in the turbine in the coolant-bleed cycle. The thermodynamic property of methane limits the operating range of methane-fueled engines. When the coolant-bleed cycle is used, the specific impulse degradation of methane-fueled engines becomes larger compared to that of hydrogen-fueled engines. This is due to methane having a lower specific heat and temperature after regenerative cooling. Even though the heat absorbing ability of methane is much lower than that of hydrogen, methane-fueled engines can operate with higher chamber pressures using the expander cycle. This is due to the larger density and the higher temperature after the regenerative cooling of liquid methane. Throttling of the methane-fueled engines does not have a great impact on the pump exit pressure in the expander cycle, whereas it increases the bleed ratio and degrades the specific impulse in the coolant bleed cycle of methane-fueled engines. [ABSTRACT FROM AUTHOR]

Background. Low birthweight (LBW) is a worldwide public health problem, demonstrating an increasing incidence in developed countries, including Japan. LBWis also a risk factor for later development of chronic kidney disease (CKD). To date, studies have not evaluated the population impacts of increasing LBWrates on renal function. Methods. Estimated glomerular filtration rate (eGFR) was evaluated in 3737 Japanese adolescent males (15-16 years old) using annual cross-sectional data over an 18-year period (1998-2015). Results. Between the initial (1998-2003) and final (2010-15) periods of the study, the mean birthweight decreased from 3213.46383.8 to 3116.26382.3 g and the LBW rate increased from 2.5 to 5.5% (both P ≤ 0.01). Additionally, the mean eGFR decreased from 105.1615.9 to 97.4613.8mL/min/1.73 m² and the prevalence of mildly reduced renal function (eGFR ≤ 60-<90 mL/min/1.73 m²) increased from 16.4 to 30.0% (both P ≤ 0.01), most evident in the LBW group (from 10.3 to 41.7%, P ≤ 0.01). The prevalence of proteinuria also increased significantly. Mildly reduced renal function was significantly associated with LBW[odds ratio (LBW3000-3999 g) 1.51; 95% confidence interval 1.00-2.55; P = 0.047]. Conclusions. In this population of Japanese adolescents, the frequency of mildly reduced renal function increased as the LBW frequency increased. Our findings may have implications for the broader Japanese population as well as for other populations in which the prevalence of LBWis increasing. [ABSTRACT FROM AUTHOR]

Narcolepsy-cataplexy is a debilitating disorder of sleep/wakefulness caused by a loss of orexin-producing neurons in the lateroposterior hypothalamus. Genetic or pharmacologic orexin replacement ameliorates symptoms in mouse models of narcolepsy-cataplexy. We have recently discovered a potent, nonpeptide OX2R-selective agonist, YNT-185. This study validates the pharmacological activity of this compound in OX2R-transfected cells and in OX2R-expressing neurons in brain slice preparations. Intraperitoneal, and intracerebroventricular, administration of YNT-185 suppressed cataplexy-like episodes in orexin knockout and orexin neuron-ablatedmice, but not in orexin receptor-deficient mice. Peripherally administered YNT-185 also promotes wakefulness without affecting body temperature in wild-type mice. Further, there was no immediate rebound sleep after YNT-185 administration in active phase in wild-type and orexindeficient mice. No desensitization was observed after repeated administration of YNT-185 with respect to the suppression of cataplexy-like episodes. These results provide a proof-of-concept for a mechanistic therapy of narcolepsy-cataplexy by OX2R agonists. [ABSTRACT FROM AUTHOR]

The laminar to turbulent transition in a pipe flow is studied from the viewpoint of momentum conservation. The transition is presumed to happen downstream of the laminar flow development. The inflow conditions to the transition region are presumed not to change at the moment of transition. The exit pressure is presumed not to change either. In the present model, the turbulent transition is a function of the ratio of the pipe length to its diameter, and becomes larger as the pipe length ratio increases. The natural transition Reynolds number calculated shows reasonable agreement with previous experimental results. The critical transition Reynolds number calculated is 1,752, and is close to the critical number of 1,760 measured previously. The distribution of difference in pressure drop between the laminar and turbulent flows corresponds to the reported location of the puffs and slugs in the Reynolds number under forced transition. [ABSTRACT FROM AUTHOR]

The effects of radiation heat transfer in rocket engine combustion chambers are studied analytically. The fuel is hydrogen, methane or ethanol, and the oxidizer is oxygen. Radiative heat fluxes are estimated using empirical equations, and convective heat flux is estimated using flux on a flat plate, with modification of circumferential length in convergence to, or divergence from, the throat. The calculated total heat flux including radiation and convection showed reasonable agreement with the flux measured experimentally. The ratio of radiative heat flux to total flux is increased up to 30% in the cylindrical section, whereas it is less than 10% at the throat. The effect of radiation on the total amount of heat transferred to the chamber is remarkable when increasing the length of the cylindrical section and diameter, respectively. It is also made clear that the conventional estimation method of heat flux based on the pipe flow model can estimate larger heat flux in small chambers, in spite of ignoring the effects of radiation. [ABSTRACT FROM AUTHOR]

The prediction method for heat flux in the pseudo-shock region is improved based on data measurements taken during ramjet-mode experiments. Combustion experiments using a ramjet-mode combustor are conducted to investigate heat flux in the pseudo-shock region. The heat flux is measured in the region with and without combustion. The heat transfer coefficient is modified using the Stanton number and specific heat under combustion. Using modified coefficients, the modified heat transfer coefficient ratios show the same relation to the pressure ratios as those without combustion. The ratio of heat transfer coefficients is calculated using a single equation. The calculation method can predict the experimental results of heat flux in the pseudo-shock region with combustion in the divergent duct. [ABSTRACT FROM AUTHOR]

Background. The role of gut microbiota in the progression of chronic kidney disease (CKD) has not been fully elucidated. Methods. Renal failure was induced in 6-week-old spontaneously hypertensive rats by 5/6 nephrectomy (Nx). We analyzed the gut microbiota population to identify the relevant species potentially involved in inducing renal damage. Human colon Caco-2 cells were used to delineate the mechanism involved in the molecular changes in the gut of Nx rats. Results. Nx rats showed an increase in Bacteroides (Bact) and a decrease in Lactobacillus (Lact) species compared with shamoperated rats. Lact, but not Bact, populations were significantly associated with urinary protein excretion. Treatment of Nx rats with 1 × 1010 CFU/kg/day Lact ameliorated increased urinary protein excretion and higher serum levels of the uremic toxins, indoxyl sulfate and p-cresyl sulfate, and serum urea nitrogen levels. Lact also attenuated systemic inflammation in Nx rats, as evaluated by serum lipopolysaccharide, interleukin-6 and Creactive protein levels. Histologically, renal sclerosis in Nx rats was restored by Lact treatment. A reduction in the expression of tight junction proteins and the Toll-like receptor 2 (TLR2), a putative Lact receptor, in the colons of Nx rats were mitigated by Lact. Treatment of Caco-2 cells with indole downregulated tight junction protein expression, which was abolished by exposure to Lact. The effects of Lact were reversed by treatment with OxPAPC, a TLR inhibitor. Similarly, the increase in the permeability of the Caco-2 cell monolayer was reversed by the administration of Lact. Lact upregulated TLR2 expression in Caco-2 cells. Lact also attenuated the increase in serum indoxyl sulfate and urea levels and urinary protein excretion in Nx rats even in the pseudogerm-free environment. Conclusions. Lact supplementation mitigated the systemic inflammation and proteinuria associated with renal failure, suggesting that in the gut microbiota, Lact plays a protective role against the progression of CKD. [ABSTRACT FROM AUTHOR]

Background. The lipodystrophy-like phenotype has been suggested in early chronic kidney disease (CKD). It includes adipose tissue atrophy, systemic insulin resistance (IR), dyslipidemia and ectopic lipid accumulation. To elucidate its pathogenesis, we investigated the role of two uremic toxins that affect insulin sensitivity: an endogenous nitric oxide synthase inhibitor, and asymmetric dimethylarginine (ADMA) and indoxyl sulfate (IS). Methods. Six-week-old Sprague-Dawley rats were rendered CKD by subtotal nephrectomy (Nx) and compared with sham-operated rats. Cultured 3T3-L1 fibroblasts were differentiated into mature adipocytes with or without ADMA. Transgenic (Tg) mice overexpressing each isoform of ADMA degrading enzyme, dimethylarginine dimethylaminohydrolase 1 (DDAH1) and DDAH2 were subject to Nx and their phenotypes were investigated. Results. In Nx rats, IR was evident and insulin stimulation failed to activate insulin signaling in adipose tissues. Adipose tissue weight, adipocyte size and adipocyte differentiation marker expressions decreased as a consequence of IR in Nx. Tissue lipid content in the liver and muscle increased in Nx rats. Tissue levels of ADMA, IS and oxidative stress increased in the adipose tissue of Nx rats. Both DDAH1 and DDAH2 expressions decreased, and a putative IS receptor, aryl hydrocarbon receptor, expression increased in the adipose tissue of Nx rats. ADMA inhibited adipocyte differentiation, triglyceride accumulation and insulin signaling, which were reversed by pretreatment with cGMP. In each type of Tg mice overexpressing DDAH1 or DDAH2, all lipodystrophy-like phenotypes induced by Nx were reversed. Conclusions. In mild CKD, dysregulation of the ADMA/DDAH pathway in adipose tissue triggers lipodystrophy-like phenotype changes, including ectopic fat depositions. [ABSTRACT FROM AUTHOR]

Abstract Interspecific competition for spawning sites between two gobiid fishes, Bathygobius fuscus and Eviota abax, was studied on a rocky shore. Large males (LM: 55–80?mm in standard length: SL) and small males (SM: 34–52?mm SL) of B. fuscus acted as nest holders and sneakers, respectively, in the early spawning season (July). The sympatric male E. abax (22–33?mm SL) was smaller than SM B. fuscus, and synchronically used rocky holes much smaller than those of LM B. fuscus. In this season, aggressions between the two species were rarely observed. In late season (August), as the number of the LM decreased, the SM converted their tactics to nest holding, occupying nests of a sizes similar to those of E. abax. Eviota abax males were dispossessed by SM and shifted their nest sites to cavities between cobbles and sandy bottom, which might be poorer nest sites than rocky holes. [ABSTRACT FROM AUTHOR]