Effects of plant- and animal-based-protein meals for a day on serum nitric oxide and peroxynitrite levels in healthy young men.

Plant-based diets that replace animal-based proteins with plant-based proteins have received increased attention for cardiovascular protection. Nitric oxide (NO) plays an essential role in the maintenance of endothelial function. However, under higher oxidative stress, NO generation produces peroxynitrite, a powerful oxidant and vasoconstrictor. Diet-replaced protein sources has been reported to decrease oxidative stress. However, the effects of plant-based protein on NO and peroxynitrite have not yet been clarified. Therefore, this study aimed to compare the effects of plant- and animal-based-protein meals for a day on NO, peroxynitrite, and NO/peroxynitrite balance. A crossover trial of two meal conditions involving nine healthy men was performed. Participants ate standard meals during day 1. On day 2, baseline measurements were performed and the participants were provided with plant-based-protein meals or animal-based-protein meals. The standard and test meals consisted of breakfast, lunch, and dinner and were designed to be isocaloric. Plant-based-protein meals contained no animal protein. Blood samples were collected in the morning after overnight fasting before and after the test meals consumption. In the plant-based-protein meal condition, serum NOx levels (the sum of serum nitrite and nitrate) significantly increased, while serum peroxynitrite levels did not change significantly. Animal-based-protein meals significantly increased serum peroxynitrite levels but showed a trend of reduction in the serum NOx levels. Furthermore, serum NO/peroxynitrite balance significantly increased after plant-based-protein meals consumption, but significantly decreased after animal-based-protein meals consumption. These results suggest that, compared with animal-based-protein meals, plant-based-protein meals increase NO levels and NO/peroxynitrite balance, which reflects increased endothelial function.

Estimated proximal tubule fluid phosphate concentration and renal tubular damage biomarkers in early stages of chronic kidney disease.

INTRODUCTION: An increase in proximal tubule fluid phosphate concentration is caused by increased serum fibroblast growth factor 23 (FGF23) levels, which resulted in renal tubular damage in a mouse model of chronic kidney disease (CKD). However, few human studies have supported this concept. This study aimed to explore the association among estimated proximal tubule fluid phosphate concentration (ePTFp), serum FGF23 levels, and renal tubular damage biomarkers in middle-aged and older populations with mild decline in renal function. METHODS: This cross-sectional study included 218 participants aged ≥45 with CKD stages G2-G4. Anthropometric measurements, blood tests, spot urine biomarkers, renal ultrasonography, cardiovascular assessment, smoking status, and medication usage were obtained in the morning in fasted states. The ePTFp was calculated using serum creatinine, urine phosphate, and creatinine concentrations. Urinary ß2-microglobulin and liver-type fatty acid-binding protein (L-FABP) levels were evaluated to assess renal tubular damage. RESULTS: ePTFp, serum FGF23, urinary ß2-microglobulin, and urinary L-FABP levels increased with CKD stage progression (stages G2, G3, and G4). However, serum and urine phosphate concentrations were comparable across the CKD stages. Univariate analysis revealed a stronger correlation of ePTFp with serum FGF23, urinary ß2-microglobulin, and urinary L-FABP levels than with the corresponding serum and urine phosphate concentrations. Multivariate analyses demonstrated that increased ePTFp was independently associated with elevated serum FGF23 and urinary ß2-microglobulin levels, even after adjusting for potential covariates, including the estimated glomerular filtration rate and urinary albumin-to-creatinine ratio. CONCLUSIONS: Our results are consistent with the concept in mouse model and suggest that increased ePTFp are associated with increased serum FGF23 levels and renal tubular damage during the early stages of CKD.

Association between the intake of plant and animal proteins and the serum fibroblast growth factor-23 level in patients with chronic kidney disease analyzed by the isocaloric substitution model.

Fibroblast growth factor-23 (FGF23) is a phosphaturic hormone secreted by the bone in response to dietary phosphate intake. Since the phosphate content in the diet correlates with the protein content, both plant- and animal-based protein intake can increase the serum FGF23 level. However, a higher percentage of energy from plant protein than from animal protein is associated with a lower serum FGF23 level in patients with chronic kidney disease (CKD) in the United States. Since dietary habits differ between Asian and Western populations, we performed a cross-sectional study to determine the association between the percentages of energy from plant and animal proteins and the serum FGF23 level in Japanese CKD patients. In 107 non-dialysis CKD patients (age: 66 ± 9 years; estimated glomerular filtration rate: 56 ± 21 mL/min/1.73 m2), the percentages of energy from plant and animal proteins were assessed using a food frequency questionnaire based on food groups. Venous blood samples were used to measure the serum FGF23, phosphate, 1,25-dihydroxyvitamin D, and intact parathyroid hormone levels. The percentages of energy from plant and animal proteins showed a negative and positive association, respectively, with the serum FGF23 level. Furthermore, isocaloric substitution modeling showed that replacing animal protein with plant protein was associated with a low serum FGF23 level. Our findings suggest that encouraging diets with high plant protein level may prevent an increase in the serum FGF23 level in Japanese CKD patients.

Effects of the number of sit-stand maneuver repetitions on baroreflex sensitivity and cardiovascular risk assessments.

Sit-stand maneuvers (SSMs) have increasingly been used for baroreflex sensitivity (BRS) measurement in physiological research, but it remains unknown as to how many SSMs need to be performed to measure BRS and assess its relationship with cardiovascular disease (CVD) risk. Therefore, this study aimed to determine 1) the effect of the number of SSM repetitions on BRS, and 2) the association between BRS and CVD risk factors. Data were collected from 174 individuals during 5 min of spontaneous rest and 5 min of repeated SSMs at 0.05 Hz (i.e., 15 cycles of 10-s sit and 10-s stand). During SSMs, BRS was calculated from the incremental cycles of 3, 6, 9, 12, and 15 SSMs using transfer function analysis of heart rate (HR) and systolic blood pressure (SBP). General CVD risk factors, carotid arterial stiffness, and cardiorespiratory fitness were measured. In result, HR and SBP increased during SSMs (P < 0.05). The BRS remained at a similar level during the resting and SSM conditions, whereas the coherence function reached its peak after 3 cycles of SSMs. BRS with ≥6 cycles of SSMs was strongly correlated with age (r = -0.721 to -0.740), carotid distensibility (r = 0.625-0.629), and cardiorespiratory fitness (r = 0.333-0.351) (all P < 0.001). Multiple regression analysis demonstrated that BRS with ≥6 cycles of SSMs explained >60% of the variance in CVD risk factors. Therefore, our findings suggest that repeated SSMs significantly strengthens the association between BRS and CVD risk factors. Particularly, BRS with ≥6 cycles of SSMs is strongly associated with CVD risk.

Associations of circulating xanthine oxidoreductase activity with cardiometabolic risk markers in overweight and obese Japanese men: a cross-sectional pilot study.

Circulating xanthine oxidoreductase (XOR) activity may contribute to the pathogenesis of obesity-related adverse cardiometabolic profiles. This pilot study aimed to examine the cross-sectional associations between plasma XOR activity and cardiometabolic risk (CMR) markers in overweight and obese men. In 64 overweight and obese Japanese men (aged 31-63 years), plasma XOR activity and several CMR markers, such as homeostasis model assessment of insulin resistance (HOMA-IR), and clustered CMR score were measured in each participant. Clustered CMR score was constructed based on waist circumference, triglyceride, blood pressure, fasting plasma glucose, and high-density lipoprotein cholesterol. Plasma XOR activity in overweight and obese men was positively associated with the body mass index, waist circumference, visceral fat area, body fat mass, hemoglobin A1c, serum 8-hydroxy-2'-deoxyguanosine, HOMA-IR, and clustered CMR score and was inversely associated with handgrip strength and high-density lipoprotein cholesterol. Multiple linear regression analysis further demonstrated that the associations of plasma XOR activity with HOMA-IR and the clustered CMR score remained significant after adjustment for covariates including uric acid. Our data demonstrate that circulating XOR activity was independently associated, albeit modestly, with HOMA-IR and the clustered CMR score. These preliminary findings suggest that circulating XOR activity can potentially be one of the preventive targets and biomarkers of cardiometabolic disorders in over-weight and obese men.

Replacing sedentary time for physical activity on bone density in patients with chronic kidney disease.

INTRODUCTION: This study aimed to examine the cross-sectional associations of sedentary time and physical activity time with bone density in patients with chronic kidney disease (CKD). The isotemporal substitution (IS) modeling was used to estimate the beneficial effects of behavioral changes (e.g., replacing sedentary time with physical activity time) on bone density in these patients. MATERIALS AND METHODS: A total of 92 patients with CKD (age: 65 ± 9 years; estimated glomerular filtration rate: 57 ± 22 mL/min/1.73 m2) were included in this cross-sectional study. The times spent in sedentary behavior (SB), light-intensity physical activity (LPA), and moderate- to vigorous-intensity physical activity (MVPA) were assessed using a triaxial accelerometer. Through quantitative ultrasound measurements, the stiffness index, as a measure of bone density, was calculated using the speed of sound and broadband ultrasound attenuation. RESULTS: In multivariate analyses, the stiffness index was beneficially associated with the MVPA time (ß = 0.748), but was not significantly associated with the SB and LPA times. The IS models showed that replacing 10 min/day of SB with the equivalent LPA time was not significantly associated with the stiffness index; however, replacing 10 min/day of SB with the equivalent MVPA time was beneficially associated with the stiffness index (ß = 0.804). CONCLUSION: These results suggest that a small increase in MVPA time (e.g., 10 min/day) may attenuate the decline in bone density in patients with CKD. Our findings may provide insight for the development of novel strategies for improving bone health in patients with CKD.

Ratio of serum creatinine to cystatin C is related to leg strength in predialysis CKD patients.

BACKGROUND AND OBJECTIVES: Chronic kidney disease (CKD) patients have lower levels of physical function. Especially, leg strength is important for daily living and preventing falls. However, physical function screenings are difficult to perform at clinical sites. To find clinically useful method to evaluate physical function in predialysis CKD patients, we tried to evaluate the relationship between the ratio of serum creatinine to serum cystatin C (Cre/CysC), and knee extensor muscle strength/body weight (KEMS) which reflects their leg strength. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: We recruited 147 outpatients with CKD (87 men; mean age, 61.6 ± 9.8 years; mean eGFRcreat, 40.7 ± 12.9 mL/min/1.73m2) in this cross-sectional study. KEMS was assessed using a wire strain gauge dynamometer. Skeletal muscle mass and body fat mass were assessed by bioelectrical impedance analysis. RESULTS: The mean value of Cre/CysC was 1.01 ± 0.18. The mean value of KEMS was 1.60 ± 0.47 Nm/kg. In multivariate linear regression analysis, skeletal muscle mass (p < 0.01), body fat mass (p < 0.01), hemoglobin (p = 0.01), and Cre/CysC (p < 0.01) was independently related to KEMS. The correlation between Cre/CysC and KEMS is stronger in high quantile of Cre/CysC. CONCLUSIONS: In predialysis CKD patients, KEMS showed lower as CKD stage advanced. Cre/CysC is significantly related to KEMS independently. Cre/CysC may be an alternative marker for leg strength in CKD patients and even more valuable to utilize in cases with high Cre/CysC.

Incremental short maximal exercise increases urinary liver-type fatty acid-binding protein in adults without CKD.

Exercise-induced redistribution of tissue blood flow decreases the renal blood flow in an exercise intensity-dependent manner. However, the acute effects of incremental short maximal exercise on renal tubular conditions remain unknown. The purpose of this study was to investigate the acute effects of incremental short maximal exercise on the urinary liver-type fatty acid-binding protein, which is a highly sensitive tubular biomarker that correlates excellently with peritubular capillary blood flow. A total of 116 adults (aged 24-83 years) without chronic kidney disease performed the incremental short maximal exercise using a cycling ergometer, wherein the exercise sequence consisted of commencing with a 2-min workout period at 20 W (as a warm-up period) and then followed by a 10-20 W increase every 1 minute until termination criteria were reached. Urinary samples were gathered before and immediately after the exercise to evaluate the concentrations of urinary creatinine, albumin, and liver-type fatty acid-binding protein. Urinary excretion levels of albumin and liver-type fatty acid-binding protein were significantly increased post-exercise (P < .001 and P = .008, respectively). Furthermore, the % change in urinary liver-type fatty acid-binding protein levels after exercise was found to correlate independently with age, estimated glomerular filtration rate at baseline, and the % change in urinary albumin (Model R2  = 0.451, P < .001). Our findings suggest that incremental short maximal exercise may lead to acute slightly adverse effects on tubular conditions, especially in young adults or adults with lower renal function, even without chronic kidney disease.

The impact of aerobic fitness on arterial stiffness and adrenal cortex hormones in middle-aged and older adults.

An increase in arterial stiffness with advance aging is a risk for cardiovascular disease. Cardiovascular dysfunction is associated with the imbalance of adrenal cortex hormones, especially with the cortisol/dehydroepiandrosterone sulfate (DHEAs) ratio. However, the impact of aerobic fitness on arterial stiffness and cortisol/DHEAs ratio is unclear. The aim of this study was to investigate the relationship between aerobic fitness, arterial stiffness, and cortisol/DHEAs ratio. A total of 198 middle-aged and older adults (aged 50-79 years old) participated in this study. The aerobic fitness evaluated by peak oxygen consumption (VO2peak), carotid-femoral pulse wave velocity (cfPWV) as an indicator of arterial stiffness, and serum cortisol and DHEAs and their ratio were measured. The subjects were divided into the lower (n = 100) and the higher (n = 98) aerobic fitness groups based on the median value of VO2peak. There were no significant differences in serum cortisol and DHEAs concentration alone between the lower and higher fitness groups. However, the cortisol/DEHAs ratio and cfPWV in the higher fitness group was smaller than in the lower fitness group (p < 0.05). The cortisol/DHEAs ratio was significantly correlated with cfPWV (r = 0.159, p < 0.05). These findings suggest that the cortisol/DHEAs ratio is associated with aerobic fitness and arterial stiffness in middle-aged and older adults.

Sedentary behaviour, physical activity, and renal function in older adults: isotemporal substitution modelling.

BACKGROUND: Physical inactivity and sedentary behaviour (too much sitting) can contribute to renal dysfunction. However, the potential benefits of behavioural change (e.g. replacing sedentary behaviour with physical activity) on renal function are not well understood. We used isotemporal substitution to model potential impacts of behaviours on renal function by replacing time spent in one behaviour to another. METHODS: In 174 older Japanese adults (age, 50-83 years; females, 76%), the time spent in sedentary behaviour, light-intensity physical activity (LPA), and moderate- to vigorous-intensity physical activity (MVPA) were assessed using an uniaxial accelerometer. Renal function was evaluated by the estimated glomerular filtration rate (eGFR) from serum creatinine and cystatin C levels. RESULTS: In univariate analyses, eGFR was significantly, albeit weakly, correlated with time spent in sedentary behaviour (rs = - 0.229), LPA (rs = 0.265), and MVPA (rs = 0.353). In the isotemporal substitution models, replacement of 30 min/day of sedentary behaviour with an equivalent LPA time was not significantly associated with eGFR (ß = 2.26, p = 0.112); however, replacement with an equivalent time of MVPA was beneficially associated with eGFR (ß = 5.49, p < 0.05). CONCLUSIONS: These cross-sectional findings suggest that sedentary behaviour (detrimentally) and physical activity (beneficially) may affect renal function and that replacing sedentary behaviour with MVPA may benefit renal health in older adults.

Urinary liver-type fatty acid-binding protein is associated with subendocardial viability ratio in middle- and older-aged adults.

BACKGROUND: To identify one of the physiological underlying mechanisms of the predictive effects of urinary liver-type fatty acid-binding protein (L-FABP) for the onset of cardiovascular disease (CVD), we investigated the relationship between urinary L-FABP levels and subendocardial viability ratio (SEVR), a marker of myocardial perfusion, in middle- and older-aged adults. METHODS: This was a cross-sectional study of 249 middle- and older-aged adults (aged 46-83 years). We measured urinary L-FABP levels and central hemodynamic parameters, including SEVR, calculated by pulse wave analysis using an applanation tonometry. RESULTS: In the participants stratified in accordance with the tertiles of urinary L-FABP levels, SEVR decreased in a stepwise fashion with increasing tertiles (p < 0.001). Furthermore, this association remains significant after the consideration of various confounders. On the contrary, urinary albumin levels were not independently related with SEVR. CONCLUSION: Our results demonstrated that urinary L-FABP levels were independently associated with the SEVR of the middle- and older-aged adults. This result suggests that the increase in urinary L-FABP levels even within the normal range might be related to the decrease in myocardial perfusion (SEVR).

Habitual exercise decreases plasma xanthine oxidoreductase activity in middle-aged and older women.

The aim of present study was to investigate the association between plasma xanthine oxidoreductase activity, which has gained attention as a novel preventive target of cardiovascular disease, and various physiological parameters and was to determine the effects of habitual exercise on plasma xanthine oxidoreductase activity in middle-aged and older women. In the cross-sectional study, we investigated the association between plasma xanthine oxidoreductase activity and various physiological parameters in 94 middle-aged and older women. In the interventional study, subjects (n = 22) were divided into two groups: exercise (n = 12) or the control group (n = 10), whereby we examined the effect of 12-week aerobic exercise training on plasma xanthine oxidoreductase activity in middle-aged and older women. The cross-sectional study demonstrated that plasma xanthine oxidoreductase activity was significantly associated with various physiological parameters, including visceral fat and daily step counts. In the interventional study, the plasma xanthine oxidoreductase activity significantly decreased after the 12-week aerobic exercise training, its changes were inversely associated with the changes in daily step counts. Our results revealed that the plasma xanthine oxidoreductase activity was associated with visceral fat accumulation and lack of exercise, and it was decreased by the aerobic exercise training.

Impact of Age and Aerobic Exercise Training on Conduit Artery Wall Thickness: Role of the Shear Pattern.

Hemodynamic shear stress is the frictional force of blood on the arterial wall. The shear pattern in the conduit artery affects the endothelium and may participate in the development and progression of atherosclerosis. We investigated the role of the shear pattern in age- and aerobic exercise-induced changes in conduit artery wall thickness via cross-sectional and interventional studies. In a cross-sectional study, we found that brachial shear rate patterns and brachial artery intima-media thickness (IMT) correlated with age. Additionally, brachial artery shear rate patterns were associated with brachial artery IMT in 102 middle-aged and older individuals. In an interventional study, 39 middle-aged and older subjects were divided into 2 groups: control and exercise. The exercise group completed 12 weeks of aerobic exercise training. Aerobic exercise training significantly increased the antegrade shear rate and decreased the retrograde shear rate and brachial artery IMT. Moreover, changes in the brachial artery antegrade shear rate and the retrograde shear rate correlated with the change in brachial artery IMT. The results of the present study indicate that changes in brachial artery shear rate patterns may contribute to age- and aerobic exercise training-induced changes in brachial artery wall thickness.

Relationship between exercise capacity and urinary liver-type fatty acid-binding protein in middle-aged and older individuals.

BACKGROUND: The underlying mechanism linking the decline in exercise capacity with renal dysfunction remains unclear. Urinary liver-type fatty acid-binding protein (L-FABP) levels reflect the degree of peritubular capillary blood flow, an important factor for renal dysfunction with aging. The aim of this study was to examine the relationship between exercise capacity and urinary L-FABP levels. METHODS: This was a cross-sectional study of 187 middle-aged and older individuals (aged 50-83 years) without chronic kidney disease (CKD). We assessed urinary L-FABP levels, peak oxygen consumption ([Formula: see text]), and grip strength. RESULTS: Urinary L-FABP levels inversely correlated with both [Formula: see text] (r s = -0.349) and grip strength (r s = -0.485). When the participants were divided into four groups according to the median values of aerobic fitness and muscular strength ([Formula: see text] and grip strength), urinary L-FABP levels were the highest in participants with lower levels of aerobic fitness and muscular strength (2.95 ± 1.43 µg/g creatinine) and the lowest in the participants with higher levels of aerobic fitness and muscular strength (1.33 ± 0.76 µg/g creatinine). The difference between the two groups was significant (P < 0.001). CONCLUSION: Our results demonstrate that both [Formula: see text] and grip strength were inversely associated with urinary L-FABP levels in middle-aged and older individuals without CKD. This suggests that a decline in exercise capacity is associated with a reduction in peritubular capillary blood flow, providing a novel insight into the underlying mechanism linking the decline in exercise capacity to the development of renal dysfunction.

Arterial stiffness of lifelong Japanese female pearl divers.

Japanese female pearl divers called Ama specialize in free diving in the cold sea for collecting foods and pearls in oysters. Exercising in the water combined with marked bradycardia and pressor responses provides a circulatory challenge to properly buffer or cushion elevated cardiac pulsations. Because Ama perform repeated free dives throughout their lives, it is possible that they may have adapted similar arterial structure and function to those seen in diving mammals. We compared arterial stiffness of lifelong Japanese pearl divers with age-matched physically inactive adults living in the same fishing villages. A total of 115 Japanese female pearl divers were studied. Additionally, 50 physically inactive adults as well as 33 physically active adults (participating in community fitness programs) living in the same coastal villages were also studied. There were no differences in age (∼65 yr), body mass index, and brachial blood pressure between the groups. Measures of arterial stiffness, cardio-ankle vascular index and ß-stiffness index were lower (P < 0.05) in pearl divers and physically active adults than in their physically inactive peers. Augmentation pressure and augmentation index adjusted for the heart rate of 75 beats/min were lower (P < 0.05) in pearl divers than in other groups. These results indicate that lifelong Japanese pearl divers demonstrate reduced arterial stiffness and arterial wave reflection compared with age-matched physically inactive peers living in the same fishing villages.

Combined effects of sleep and objectively-measured daily physical activity on arterial stiffness in middle-aged and older adults.

Although sleep quality and physical activity (PA) may influence on arterial stiffness, the combined effects of these two factors on arterial stiffness remain unknown. A total of 103 healthy middle-aged and older men and women (aged 50-83 years) with no history of cardiovascular disease and depression were included in this study. Arterial stiffness was measured using carotid-femoral pulse wave velocity (cfPWV), brachial-ankle PWV (baPWV), and femoral-ankle PWV (faPWV). Poor sleepers were defined as those with a Pittsburgh Sleep Quality Index score of >5.5. Using an accelerometer for seven consecutive days, low levels of PA were defined as low moderate-to-vigorous-intensity PA (MVPA) <19.0 min/day and low step counts <7100 steps/day, respectively. Poor sleepers with low PA levels, as determined by MVPA and daily steps, showed higher cfPWV, but not faPWV or baPWV, in middle-aged and older adults. Furthermore, in the analysis of covariance (ANCOVA) analyses adjusted for age, obesity, dyslipidemia, and sedentary behavior, the cfPWV result remained significant. Our study revealed that the coexistence of poor sleep quality and decreased PA (low MVPA or daily steps) might increase central arterial stiffness in middle-aged and older adults. Therefore, adequate sleep (good and sufficient sleep quality) and regular PA, especially at appropriate levels of MVPA (i.e., at least of 7100 steps/day), should be encouraged to decrease central arterial stiffness in middle-aged and older adults.

Exercise instruction during haemodialysis treatment after changes to the insurance regime: a nationwide questionnaire survey in Japan.

In April 2022, an additional medical fee for exercise instruction during haemodialysis treatment was approved for insurance claims in Japan. We conducted a questionnaire survey to investigate the current situation regarding exercise therapy during haemodialysis treatment after this change. Questionnaires were mailed to 4257 haemodialysis facilities, almost all the haemodialysis facilities in Japan, on January 31, 2023. In total, 1657 facilities responded, of which 550 (33%) provided exercise instruction during haemodialysis treatment, and 65% of these claimed the new fee. Of the 550 facilities that had claimed the fee at the time of survey, 245 (55%) started exercise instruction in April 2022 or later. Exercise instruction focused on resistance training (81%) and aerobic exercise (62%) for 20-30 min (66%) three times a week (80%). The instructors included physicians in 45% of facilities, nurses in 74%, and physical therapists in 36%. Efficacy was evaluated in 76% of the facilities providing instruction, mainly by assessing change in muscle strength (49%). Overall, 39% of facilities had experienced some adverse events, but none were life-threatening. In conclusion, after the change in the insurance regime, exercise instruction during haemodialysis treatment has become more popular, and more patients on haemodialysis are undergoing exercise therapy.

Impact of Plant and Animal Protein-Based Meals on Serum Fibroblast Growth Factor-23 Levels in Healthy Young Men: A Randomized Crossover Trial.

Fibroblast growth factor-23 (FGF23) is a phosphaturic hormone secreted by osteocytes in response to dietary phosphate intake. An increase in FGF23 level is an indicator of excess phosphate intake relative to the residual nephron number. Therefore, avoiding excessive phosphate intake and inhibiting the elevation of serum FGF23 levels are important to preserve the number of functional nephrons. This randomized crossover trial aimed to determine the potential differences in the impacts on serum FGF23 levels between plant protein and animal protein-based meals in individuals with normal renal function. Nine young men were administered plant (no animal protein) or animal protein-based meals (70% of their protein was from animal sources) with the same phosphate content. The test meals consisted of breakfast, lunch, and dinner. Blood samples were collected in the morning, after overnight fasting, and before and after eating the test meals (for two consecutive days at the same hour each day). Furthermore, a 24-h urine sample was obtained on the day the test meal was consumed. No significant interactions were found among serum phosphate, calcium, and 1,25-dihydroxyvitamin D levels. However, after eating plant protein-based meals, serum FGF23 levels decreased and serum intact parathyroid hormone levels increased (interaction, p<0.05). Additionally, urine 24-h phosphate excretion tended to be lower in individuals consuming plant protein-based meals than in those consuming animal protein-based meals (p=0.06). In individuals with normal renal function, plant protein-based meals may prevent an increase in serum FGF23 levels and kidney damage caused by phosphate loading.

Elevated urinary angiotensinogen excretion links central and renal hemodynamic alterations.

Inappropriate activation of intrarenal renin-angiotensin system (RAS) may contribute to the pathogenesis of cardio-renal syndrome (CRS). We aimed to examine the cross-sectional associations of urinary angiotensinogen (AGT) excretion, a biomarker of intrarenal RAS activity, with central (aortic) and renal hemodynamic parameters in middle-aged and older adults, including patients with chronic kidney disease. Aortic and renal hemodynamic parameters were measured using applanation tonometry and duplex ultrasonography in 282 participants. Urinary AGT, liver-type fatty acid-binding protein (L-FABP), and plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were measured for each participant. Multiple linear regression analyses demonstrated that urinary AGT levels were associated with aortic blood pressures, pulsatile measures of renal blood flow, plasma NT-proBNP and urinary L-FABP levels after adjusting for potential covariates, including age, sex, body mass index, estimated glomerular filtration rate (GFR), and medication use. Additionally, when classified based on GFR stages and urinary AGT levels, plasma NT-proBNP and urinary L-FABP levels increased in participants with lower GFR and higher AGT groups. Our findings suggest that urinary AGT excretion is a shared determinant of central (aortic) and renal hemodynamics in middle-aged and older adults, providing clinical evidence for the potential role of intrarenal RAS activity in the development of CRS.

Association between trunk flexibility and renal flow pulsatility in middle-aged and older adults.

BACKGROUND: Recent clinical studies have indicated that poor trunk flexibility is associated with arterial stiffness in the aged. Arterial stiffness leads to elevated renal flow pulsatility, which accelerates age-related renal dysfunction and damages. However, data indicating the potential link between flexibility fitness and renal flow pulsatility are lacking. This study examined the cross-sectional association between trunk flexibility and renal flow pulsatility in middle-aged and older adults. METHODS: A total of 175 middle-aged and older adults (aged 63 ± 9 years) were included in this study. Sit-and-reach tests (SRT) were performed to assess their trunk flexibility. Using a Doppler ultrasound, renal pulsatility index (PI) and resistive index (RI) were measured as parameters of renal flow pulsatility. RESULTS: The study found that, in middle-aged and older adults, the SRT score was an independent determinant of renal PI (ß = -0.134, P = 0.027) and RI (ß = -0.135, P = 0.027). In the one-way analysis of covariance (ANCOVA), the renal PI and RI in the older group with a lower SRT score were found to be significantly higher than those in the middle-aged group. CONCLUSIONS: Trunk flexibility is an independent determinant of renal flow pulsatility in middle-aged and older adults.