Effects of creatine supplementation on body composition and renal function in rats

BACKGROUND: The aim of the present study was to evaluate the long-term effects of oral creatine supplementation on renal function and body composition (fat and lean mass) in an experimental model. METHODS: Male Wistar rats were supplemented with creatine (2 g.kg(-1) of food) for 10 wk in combination with treadmill exercise, 12 m.min(-1), 1 h.d(-1) (CREAT + EX, N = 12) or not (CREAT, N = 10), and compared with exercised animals without creatine supplementation (EX, N = 7) and CONTROL animals, N = 7. Body composition and bone mineral density (BMD) were determined by dual x-ray absorptiometry and glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured by inulin and paraaminohippurate clearance, respectively. RESULTS: At the end of the study (post), CREAT+EX presented higher lean mass and lower fat mass than CREAT, EX or CONTROL (349.7 +/- 19.7 vs 313.3 +/- 20.3, 311.9 +/- 30.8, 312.4 +/- 21.0 g and 5.7 +/- 2.3 vs 10.0 +/- 3.3, 9.8 +/- 1.5, 10.0 +/- 3.5%, P < 0.05, respectively). Post lean/fat mass ratio was higher than baseline only in CREAT + EX (18.9 +/- 7.2 vs 8.6 +/- 1.8, P < 0.05). Post BMD was significantly higher than baseline in all groups. GFR and RPF were lower in CREAT versus CONTROL (0.5 +/- 0.1 vs 1.0 +/- 0.1 and 1.5 +/- 0.2 vs 2.4 +/- 0.5 mL.min(-1), P < 0.05, respectively). CONCLUSION: Creatine supplement in combination with exercise increased the proportion of lean mass more than EX or CREAT alone. The use of creatine alone induced an important and significant reduction of both RPF and GFR.     

Quantitative assessment of glomerular filtration rate with MR gadolinium slope clearance measurements: a phase I trial

PURPOSE: To prospectively demonstrate the feasibility of quantifying the glomerular filtration rate (GFR) by assessing the renal clearance of gadolinium-based contrast medium from the extracellular fluid volume in healthy volunteers. MATERIALS AND METHODS: The study was approved by the ethics committee and the governmental drug administration department (registration number 4030139, EudraCT number 2004-002969-20, study protocol number 318/2004). Informed consent was obtained from 16 healthy volunteers (six female, 10 male; mean age, 24.5 years +/- 2.8 [standard deviation]). Thirteen volunteers (four women, nine men; mean age, 24.8 years +/- 2.7; range, 23-30 years) successfully contributed to the study. The GFR was assessed by recording the renal clearance of gadobutrol (3.75 mL, approximately 0.05 mmol per kilogram of body weight) at navigator-gated turbo fast low-angle shot magnetic resonance (MR) imaging. Time-signal intensity curves were constructed from manually drawn regions of interest in the liver, spleen, and renal cortex, and the GFR was calculated by using exponential fitting. Simultaneously obtained iopromide clearance measurements were the reference standard. Statistical evaluations included Bland-Altman plotting and analysis of the relative deviation from iopromide clearance. RESULTS: Evaluation of liver regions of interest revealed the lowest mean of paired differences from the iopromide clearance measurements (-5.9 mL/min per 1.73 m(2) +/- 14.6), with a mean GFR of 109.0 mL/min per 1.73 m(2) +/- 17.1 (134.1 mL/min per 1.73 m(2) +/- 35.4 for spleen, 100.7 mL/min per 1.73 m(2) +/- 25.1 for renal cortex) compared with a mean GFR of 103.1 mL/min per 1.73 m(2) +/- 9.4 measured by using iopromide clearance. The maximum deviation of MR-determined gadobutrol clearance values from iopromide clearance values was 29.2%. The mean disposition half-life of gadobutrol measured in the liver was 83.0 minutes +/- 14.2 (72.4 minutes +/- 20.2 in spleen, 92.6 minutes +/- 23.7 in renal cortex). CONCLUSION: The described MR imaging method enables absolute quantification of the GFR after routine contrast material-enhanced MR imaging.     

Normalization of diastolic dysfunction in type 2 diabetics after exercise training

PURPOSE: The purpose of this study was to evaluate the impact of aerobic exercise training on left ventricular diastolic dysfunction (LVDD) and exercise capacity in subjects with type 2 diabetes. METHODS: Twenty-three sedentary subjects with well-controlled type 2 diabetes, free of coronary disease and having different degrees of LVDD, participated in the study. Subjects were treated with oral hypoglycemic agents and/or diet. Eleven subjects (EX) (age: 58 +/- 5 yr; mean +/- SD) underwent a 3-month aerobic exercise training program using a cycle ergometer, whereas a control group (CONT) of 12 subjects (57 +/- 6 yr) maintained their activities of daily living. Exercise capacity and LVDD, using echocardiography, were evaluated before and after the 3-month exercise program. RESULTS: At baseline, anthropometric data were similar between the groups, except for body mass index (BMI), which was higher in CONT (31 +/- 3 vs 28+/- 3 kg x m(-2); P < 0.05). There were no significant differences in glycemic control (HbA1c: 6.4 +/- 1.2 vs 5.8 +/- 1.3%; P = 0.2) or maximal oxygen uptake (26.7 +/- 5.9 vs 28.6 +/- 3.9 mL x kg(-1) x min(-1); P = 0.4) between groups. Normalization of LVDD was observed in 5 of 11 EX subjects, (P < 0.0001) of whom four had grade 1 LVDD before exercise training. No change in diastolic function was observed in the CONT group. After exercise training, maximal oxygen uptake increased in the EX group (28.6 +/- 3.9 vs 32.7 +/- 5.7 mL x kg(-1) x min(-1); P < 0.05), whereas there was no change in the CONT group (26.7 +/- 5.9 vs 27.3 +/- 6.2 mL x kg(-1) x min(-1); P = 0.58). In both groups, there was no significant change in BMI. CONCLUSIONS: Along with an improvement in exercise capacity, aerobic exercise training has the potential to reverse LVDD in patients with well-controlled, uncomplicated type 2 diabetes.     

Regular exercise as an effective approach in antihypertensive therapy

PURPOSE: Exercise has been well documented to exert a beneficial effect on cardiovascular health. The effective control of arterial pressure (BP) is essential from the standpoint of cardiovascular prevention. So far, no study has determined the long-term effect of regular training as a monotherapy on both BP at rest and during exercise. METHODS: Therefore, 10 subjects with hypertension (aged 43 +/- 3 yr) were studied in order to define BP response to long-term aerobic training. BP measurements were obtained at rest and during ergometry (50-100 W). Patients were instructed to exercise weekly (2 x 60 min aerobic exercise). RESULTS: BP during exercise (100 W) did fall already after 6 months of regular training from 184 +/- 10/107 +/- 6 to 170 +/- 10/100 +/- 7, and this was associated with a 14% decrease in the rate-pressure product (at 100 W). After 18 months of training, there were further reductions in BP, at rest from 139 +/- 9/96 +/- 6 to 133 +/- 14/91 +/- 7 (P < 0.05) and during ergometry (100 W) from 184 +/- 10/107 +/- 6 to 172 +/- 8/96 +/- 6 mm Hg (P < 0.001). During a 3-yr follow-up, BP continued to decrease significantly to 130 +/- 13/87 +/- 7 mm Hg at rest and 167 +/- 9/92 +/- 6 mm Hg during exercise. No significant changes in body weight were documented during the training period. CONCLUSION: The data demonstrate that long-term aerobic exercise is associated with a decrease in BP at rest and during exercise, which is comparable to that of drug therapies. This antihypertensive effect of regular training can be maintained as long as 3 yr.     

Acute variation of estimated glomerular filtration rate following a half-marathon run

The accurate estimation of glomerular filtration rate (GFR) is pivotal in sports medicine. However, there is controversial information on the acute influence of physical exercise on kidney function in healthy athletes. The estimated GFR (EGFR) was assessed by the recommended Modification of Diet in Renal Disease (MDRD) equation before a 21-km half-marathon, at the end, and 3, 6, 24 hrs thereafter on 17 trained, middle-aged males. Results were corrected for plasma volume changes. The mean EGFR at the baseline was 76 mL/min/1.73 m (2); it decreased at the end of the run (62 mL/min/1.73 m (2)) and for the following 3 hrs (68 mL/min/1.73 m (2)) and 6 hrs (70 mL/min/1.73 m (2)), though statistical significance was only achieved immediately after the run (mean decrease 16 %, p < 0.01). The frequency of athletes with EGFR below the normal threshold was higher than the baseline immediately after the race and for the following 6 hrs. Twenty-four hours after the run, the EGFR had returned to values similar and nonsignificantly different from those recorded at the baseline. These results attest that medium to high strains of running in healthy, middle-aged, trained individuals do not cause renal damage, but a limited and temporary decline in renal function.     

Development of formulae for accurate measurement of the glomerular filtration rate by renal dynamic imaging

AIM: Currently, the widely adopted renal dynamic imaging in clinical practice uses Gates' method to calculate the glomerular filtration rate (GFR), but many researchers have proven that Gates' method may result in bias. Thus, this article explores alternative improved formulae to calculate GFR by renal dynamic imaging. METHODS: Three hundred and sixty-seven patients were selected and their GFR values were measured using renal dynamic imaging and the two-plasma method with 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA) as the imaging agent. With the two-plasma GFR as reference value, two equations were obtained from linear and non-linear regression analyses between the renal uptake percentage and two-plasma GFR. The 367 patients were divided into two random groups, with the first group used to derive the regression formulae and the second to verify the formulae. Finally, all patients were studied to derive the formulae to calculate GFR. The comparison of our formulae with the commonly used Gates' formula was conducted by the Bland-Altman method. RESULTS: The linear and non-linear GFR formulae were as follows: GFR (ml/min/1.73 m2)=(631.633 x renal uptake percentage - 2.040) x 1.73/BSA (BSA, body surface area) and GFR (ml/min/1.73 m2)=(-1996.585 x renal uptake percentage2 + 1013.526 x renal uptake percentage - 12.739) x 1.73/BSA, respectively. The biases of the GFR values calculated using the linear and non-linear formulae and Gates' formula relative to the two-plasma GFR were -2.5 +/- 19.1 ml/min/1.73 m2, -2.0 +/- 19.3 ml/min/1.73 m2 and 3.4 +/- 19.4 ml/min/1.73 m2, respectively. CONCLUSIONS: The GFR values calculated using our new formulae correlate better with the reference GFR value than does GFR calculated by Gates' formula, and the GFR values measured using the non-linear formula are more accurate than those obtained using the linear formula.     

Physiological changes following a 12 week gym based stair-climbing, elliptical trainer and treadmill running program in females

AIM: Despite the growing popularity in recent years of the elliptical trainer aerobic exercise modality the physiological changes induced following a training program using elliptical trainers remains unknown. The present study investigated the metabolic and cardiorespiratory improvements following a 12-week aerobic training program using elliptical trainer, treadmill or stair-climbing modalities. METHODS: Twenty-two moderately active females (28.6 +/- 5.3 y, 1.65 +/- 0.05 m) were randomly assigned to treadmill running (n=7), elliptical trainer (n=8) or stair-climber (n=7) groups and trained 3 days x week(-1) initially at 70-80% of maximum heart rate (HRmax) for 30 min, progressing to 80-90% HRmax for 40 min. Subjects performed incremental exercise to volitional exhaustion using an electronically loaded cycle ergometer before and upon completion of the program. In addition, subjects performed sub-maximal fixed load tests at 0, 4, 8 and 12 weeks, using ergometers specific to their exercise group. RESULTS: No significant inter-group differences were recorded for pre-training VO2max or VEmax. Significant (p<0.05) post-training increases in cycling VO2max and VEmax were observed for treadmill (mean +/- SEM, 40.7 +/- 2.2 vs 43.4 +/- 2.6 ml x kg(-1) x min(-1) and 82.9 +/- 5.1 vs 90.2 +/- 6.4 l x min(-1)), elliptical trainer (36.9 +/- 2.5 vs 39.6 +/- 2.4 ml x kg(-1) x min(-1) and 86.8 +/- 2.3 vs 92.5 +/- 4.1 l x min(-1)) and stair-climber (37.4 +/- 2.9 vs 39.2 +/- 3.1 ml x kg(-1) x min(-1) and 95.9 +/- 5.8 vs 97.4 +/- 5.8 l x min(-1)) modalities, however, the increases were not significantly different between groups. For all groups, sub-maximal HR significantly decreased from week 0 to 4, and from week 4 to 8. CONCLUSION: In moderately active females similar physiological improvements were observed using stair-climber, elliptical trainer and treadmill running when training volume and intensity were equivalent.     

Rapid determination of glomerular filtration rate in infants using Tc-99m DTPA.

Glomerular filtration rate obtained by using Tc-99m DTPA was compared with that obtained from Schwartz's formula using serum creatinine and length in 21 infants (age range, 3 to 348 days). The GFR (mean +/- SD) obtained by Tc-99m DTPA was 76 +/- 37 ml/min per 1.73m2 and by the Schwartz formula was 83 +/- 49 ml/min per 1.73m2. GFR by Tc-99m DTPA method overestimated GFR by 3.6% compared to the Schwartz method. The imaging technique and the advantages are discussed.     

不同肾小球滤过率检测方法在多囊肾肾功能评价中的临床价值

目的探讨99Tcm-二亚乙基三胺五乙酸（99Tcm-DTPA）肾动态显像Gate's法及血肌酐估测法在多囊肾各时期肾小球滤过率（GFR）检测中的应用价值。方法选择2006年1月至2018年9月未行透析治疗的多囊肾患者59例。参考美国慢性肾脏病及透析的临床实践指南,依据慢性肾病（CKD）分期（1~5期）,以双血浆法测定GFR为参考标准,将多囊肾患者分为3组。A组:GFR ≥ 60 mL/（min·1.73m2）,CKD分期为1~2期,共19例;B组:60 mL/（min·1.73 m2）>GFR ≥ 30 mL/（min·1.73 m2）,CKD分期为3期,共23例;C组:GFR < 30 mL/（min·1.73 m2）,CKD分期为4~5期,共17例。将Gate's法、血肌酐估测法测定的GFR分别与双血浆法测定的结果进行配对t检验和Pearson相关分析。结果（1）血肌酐估测法测得的A、B、C 3组的GFR分别为（85.43±19.77）、（46.56±15.48）、（20.96±11.3）mL/（min·1.73 m2）,双血浆法测得的GFR分别为（80.58±16.2）、（42.66±7.63）、（18.61±7.21）mL/（min·1.73 m2）,两者间的差异均无统计学意义（t=-1.462、-1.592、-1.791,均P>0.05）,且均有很好的相关性（r=0.69、0.68、0.92,均P < 0.05）。（2）Gate's法测得的A、B、C 3组的GFR分别为（75.39±20.75）、（42.86±18.95）、（25.85±14.91）mL/（min·1.73 m2）,与双血浆法测定的GFR比较,两者在A、B组中的差异均无统计学意义（t=1.255、-0.061,均P>0.05）,且均有很好的相关性（r=0.55、0.62,均P < 0.05）;但是,两者在C组中的差异有统计学意义（t=-2.132,P < 0.05）,且无明显相关性（r=0.36,P>0.05）。结论Gate's法可很好地评估多囊肾CKD分期为1~3期的患者的肾功能GFR,但对CKD分期为4~5期的患者不适合。血肌酐估测法可有效评价多囊肾CKD各时期的肾功能GFR。     

Obesity and postexercise oxidative stress in older women

PURPOSE: This study compared lipid peroxidation values in nonobese and obese postmenopausal women before and after acute maximal aerobic exercise (AX). METHODS: Blood samples were collected in nonobese (22.1 +/- 0.9% body fat) and obese (40.8 +/- 0.9% body fat) women (61-75 yr, N = 34) before and immediately after a maximal graded treadmill test. Lipid hydroperoxides (PEROX), cholesterol, and thiol profiles were measured. Oxygen consumption (V(O2), respiratory exchange ratios (RER), and minute ventilation (VE) values were determined before and during exercise. RESULTS: PEROX levels were not different between the nonobese and obese groups at baseline (2.4 vs 2.8 nmol.mL(-1), respectively) or post-AX (2.8 vs 3.2 nmol.mL(-1), respectively) (P > 0.05). When expressed as DeltaPEROX (nmol.mL(-1))/DeltaVO(2) (mL.kg(-1).min(-1)), to account for different exercise durations, the obese group had a greater lipid peroxidation response compared with the nonobese group (0.13 vs 0.02 (nmol.mL(-1)).mL(-1).kg(-1).min(-1), respectively; P < 0.05). Regression analysis revealed that when baseline PEROX and body fat values were controlled, age, exercise intensity, and duration were significant contributors to the DeltaPEROX/DeltaV(O2) after AX (R(2) = 0.536 P < 0.05). CONCLUSION: For a given oxidative challenge (exercise-associated oxygen utilization), older, obese women were at a greater risk for oxidative stress compared with nonobese counterparts.     

The relative contributions of anaerobic and aerobic energy supply during track 100-, 400- and 800-m performance

AIM: The present study set out to identify the relative contribution of the laboratory determined physiological measures, (maximal) accumulated oxygen deficit (AOD) and maximal oxygen uptake (VO(2max)), when predicting track performance. METHODS: Fourteen volunteers (men: n=10; women: n=4); mean (+/- standard deviation [SD]) height 1.76+/-0.1 (men) vs 1.62+/-0.08 m (women); body mass: 67.9+/-7.1 (men) vs 50.6+/-8.2 kg (women), ran track races at distances of 100, 400 and 800 m. The individually determined (maximal) AOD and VO(2max) were measured under controlled laboratory conditions (68.3+/-10.2 vs 60.7+/-16.1; men vs women, mL x (2) x Eq x kg(-1)) and (68.7+/-7.3 vs 55.6+/-4.3; men vs women, mL x kg(-1) x min(-1)), respectively. RESULTS: Track performance could be predicted using both laboratory measures, AOD and , with a high degree of accuracy: R2=76.9%, 84.8% and 89.1% for 100, 400 and 800 m, respectively. Data analysis confirmed the dominant energy supply during 100-m sprinting was the anaerobic energy supply processes, reflected as AOD. In contrast, oxidative metabolism (reflected as VO(2max)) was the dominant source of energy supply during 800-m performance. CONCLUSION: The results support earlier research, rather than present textbook dogma, namely that aerobic and anaerobic processes contribute equally to maximal exercise lasting approximately 60 s.     

Relationship between the renal apparent diffusion coefficient and glomerular filtration rate: preliminary experience

PURPOSE: To investigate the relationship between ADC values measured by diffusion-weighted MRI (DWI) and the split glomerular filtration rate (GFR). MATERIALS AND METHODS: DWI (b = 0 and 500 seconds/mm(2)) was performed with a 1.5 T MR unit in 55 patients. The ADCs were calculated with ROIs positioned in the renal parenchyma, and the split GFRs were measured by (99)Tc(m)-DTPA scintigraphy using Gates' method. The 110 kidneys were divided into four groups: normal renal function (GFR 40 mL x minute(-1)), mild renal impairment (40 > GFR > or = 20 mL x minute(-1)), moderate renal impairment (20 > GFR > or = 10 mL x minute(-1)), and severe renal impairment (GFR < 10 mL x minute(-1)). The renal ADCs between four groups were statistically compared by analysis of variance (ANOVA), and the relationship between ADCs and GFR was examined using Pearson's correlation test. RESULTS: The mean renal ADCs of the four groups were 2.87 +/- 0.11, 2.55 +/- 0.17, 2.29 +/- 0.10, and 2.20 +/- 0.11 x 10(-3)mm(2)/second, respectively. There was a statistically significant difference in renal ADCs among the four groups (P < 0.001). There was a positive correlation between the ADCs and split GFR (r = 0.709). CONCLUSION: The ADCs were significantly lower in impaired kidneys than in normal kidneys, and there was a positive correlation between the ADCs and GFR.     

Maximal physiological responses between aquatic and land exercise in overweight women

PURPOSE: To investigate the maximal physiological responses between aquatic and land-based graded exercise tests in overweight women. METHODS: Twenty healthy, overweight (body mass index (BMI) > or = 25 kg.m(-2)), Caucasian women (mean +/- SD; age 48 +/- 7 yr, BMI 30 +/- 4 kg.m(-2)) completed a deep water running (DWR) and treadmill walking (TMW) graded exercise test. Maximal responses during the DWR and TMW graded exercise tests were compared using paired t-tests. Comparisons were made in the incidence of achievement of maximal oxygen consumption (VO2max) criteria between DWR and TMW protocols. Criteria were a plateau in VO2 (change < 2.1 mL.kg.min(-1)), heart rate (HR) equal to or above the age-adjusted maximum, and respiratory exchange ratio (RER) > or = 1.15. RESULTS: Maximal responses for VO2max (22.5 +/- 4.86 vs 27.7 +/- 4.73 mL.kg.min(-1)), HRmax (159 +/- 16 vs 170 +/- 12 bpm), and RER (1.03 +/- 0.06 vs 1.10 +/- 0.06) were significantly lower (P < 0.01) for the DWR test compared with the TMW test, respectively. Achievement of various VO2max criteria was demonstrated more consistently during the TMW test than the DWR test. CONCLUSION: Maximal physiological responses of overweight women to DWR and TMW are significantly different but are comparable with other populations. As the maximal responses for DWR compared with TMW differ, the use of land-based criteria for VO2max is not recommended for a graded DWR exercise test.     

Sodium loading aids fluid balance and reduces physiological strain of trained men exercising in the heat

PURPOSE: This study was conducted to determine whether preexercise ingestion of a highly concentrated sodium beverage would increase plasma volume (PV) and reduce the physiological strain of moderately trained males running in the heat. METHODS: Eight endurance-trained (.VO2max: 58 mL.kg(-1).min(-1) (SD 5); 36 yr (SD 11)) runners completed this double-blind, crossover experiment. Runners ingested a high-sodium (High Na+: 164 mmol Na+.L(-1)) or low-sodium (Low Na+: 10 mmol Na+.L(-1)) beverage (10 mL.kg(-1)) before running to exhaustion at 70% .VO2max in warm conditions (32 degrees C, 50% RH, V(a) approximately equal to 1.5 m.s(-1)). Beverages (approximately 757 mL) were ingested in seven portions across 60 min beginning 105 min before exercise. Trials were separated by 1-3 wk. Heart rate and core and skin temperatures were measured throughout exercise. Urine and venous blood were sampled before and after drinking and exercise. RESULTS: High Na+ increased PV before exercise (4.5% (SD 3.7)), calculated from Hct and [Hb]), whereas Low Na+ did not (0.0% (SD 0.5); P = 0.04), and involved greater time to exercise termination in the six who stopped because of an ethical end point (core temperature 39.5 degrees C: 57.9 min (SD 6) vs 46.4 min (SD 4); P = 0.04) and those who were exhausted (96.1 min (SD 22) vs 75.3 min (SD 21); P = 0.03; High Na+ vs Low Na+, respectively). At equivalent times before exercise termination, High Na+ also resulted in lower core temperature (38.9 vs 39.3 degrees C; P = 0.00) and perceived exertion (P = 0.01) and a tendency for lower heart rate (164 vs 174 bpm; P = 0.08). CONCLUSIONS: Preexercise ingestion of a high-sodium beverage increased plasma volume before exercise and involved less thermoregulatory and perceived strain during exercise and increased exercise capacity in warm conditions.     

Glomerular filtration rate in endurance athletes.

OBJECTIVE: The interpretation of biochemical testing in sportsmen requires caution. Although creatinine-based estimates of glomerular filtration rate (GFR) overcome some shortcomings of serum creatinine, there is scarce information on their use in endurance athletes. DESIGN: We evaluated GFR, estimated by the recommended Modification of Diet in Renal Disease (MDRD) equation in athletes. PARTICIPANTS: Seventy-six professional male cyclists, 71 amateur male cyclists, and 65 healthy sedentary matched controls were included in the study. RESULTS: The mean serum creatinine level was significantly higher in the sedentary subjects (81 microM) than in amateur (75 microM; P < 0.001) and professional cyclists (72 microM; P < 0.001), and it was also marginally higher in amateur than in professional cyclists (P = 0.049). The mean estimated GFR value increased throughout the three subgroups, being significantly lower in the sedentary population (98 mL.min.[1.73 m]) than in the subgroups of amateur (109 mL.min.[1.73 m]; P < 0.001) and professional cyclists (113 mL.min.[1.73 m]; P < 0.001), but it did not differ between amateur and professional cyclists (P = 0.116). The average intensity of daily physical exercise, but not the body mass index, was inversely associated with serum creatinine and positively associated with the estimated GFR. CONCLUSIONS: The MDRD equation should be used with caution in athletes, and it should consider intensity and type of physical exercise.     

99mTc-MAG3: dynamic studies in patients with renal disease

Animal studies have suggested that 99mTc-mercapto-acetylglycyl-glycyl-glycine (99mTc-MAG3) might be suitable for the determination of the renal plasma flow (RPF) because of its high renal clearance. In this study 131I-orthoiodohippurate (131I-OIH) and 99mTc-MAG3 (labeling always greater than 95%) were administered simultaneously in 11 patients (creatinine clearance ranging from 14 to 130 ml/min per 1.73 m2) to measure effective RPF(ERPF) using the standard technique (UV/P). Glomerular filtration rate (GFR; clearance of 125I-thalamate, 125I-OT) was also measured. The mean ratio of 99mTc-MAG3 clearance to 131I-IOH clearance was 0.55 +/- 0.02 (SEM), P less than 0.01, n = 16, and was independent of GFR and ERPF. To study this difference in renal handling of the radiopharmaceuticals, renal extractions by the right kidney were determined in another six patients after a single shot of the agents. Renal extraction of 99mTc-MAG3 was 0.60 +/- 0.03 after 5 min, and 0.41 +/- 0.08 after 30 min. Renal extraction of 131I-OIH amounted to 0.86 +/- 0.04 and 0.77 +/- 0.03, respectively. Using renal extractions of 0.41 and 0.77, respectively, it appeared that calculated renal plasma flows measured simultaneously with 99mTc-MAG3 and 131I-OIH were similar. Protein binding 30 min after the priming dose was 66% for 99mTc-MAG3 and 47% for 123I-OIH. We conclude that in spite of a high renal clearance (ratio to 125I-OT clearance 2.69 +/- 0.27), 99mTc-MAG3 seems unsuitable for an accurate determination of the RPF.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reference data for 51Cr-EDTA measurements of the glomerular filtration rate derived from live kidney donors

BACKGROUND AND AIM: 51Cr-Ethylenediaminetetraacetic acid (51Cr-EDTA) is widely used to measure the glomerular filtration rate (GFR) for the assessment of renal function. The aims of this study were to assess the dependence of GFR on age and gender and to produce reference data for the interpretation of 51Cr-EDTA GFR measurements in adults. METHODS: This was a retrospective study of 428 subjects (218 females, 210 males; age range, 19-72 years) undergoing assessment as live kidney donors. GFR was evaluated from 51Cr-EDTA plasma clearance using blood samples taken at 2, 3 and 4 h. The slope-intercept GFR was corrected for body surface area using the Haycock formula and for the fast exponential using the Brochner-Mortensen equation. The data were analysed for the dependence on age and gender using multivariate regression analysis. Precision was evaluated from duplicate measurements in 22 subjects. RESULTS: For 187 subjects, aged 19-40 years, the dependence of GFR on age was not statistically significant (P = 0.51). The mean GFR was 103.4 ml x min(-1) x (1.73 m2)(-1) with a root mean standard error (RMSE) of 15.5 ml x min(-1) x (1.73 m2)(-1). GFR was 1.3 ml x min(-1) x (1.73 m2)(-1) higher in men than in women, although the difference was not significant (P = 0.56). In 241 subjects, aged 40-73 years, GFR decreased by 0.91 ml x min(-1) x (1.73 m2)(-1) per year [standard error, 0.06 ml x min(-1) x (1.73 m2)(-1) per year] with an RMSE of 13.6 ml x min(-1) x (1.73 m2)(-1). Over both age groups GFR was 0.4 ml x min(-1) x (1.73 m2)(-1) higher in men than in women [P=0.80; 95% confidence interval, -2.4 to +3.1 ml x min(-1) x (1.73 m2)(-1)]. For the 22 subjects with duplicate measurements, the root mean square coefficient of variation was 10.4%.CONCLUSIONS: A model for the decline of GFR with age was produced in which GFR remains constant at 103.4 ml x min(-1) x (1.73 m2)(-1) until the age of 40 years and then declines at a rate of 9.1 ml x min(-1) x (1.73 m2)(-1) per decade. The data can be used to report the results of adult 51Cr-EDTA GFR investigations.     

Aftereffects of exercise and relaxation on blood pressure.

OBJECTIVE: To study the acute aftereffects of exercise and relaxation, performed alone and in combination, on blood pressure (BP) measured at baseline and during stressful conditions. DESIGN: Clinical trial with comparison of groups and repeated measures in each group. SETTING: Exercise Hemodynamic Laboratory, University of S?o Paulo, Brazil. PARTICIPANTS: Fourteen normotensive (NT) and 16 essential hypertensive (HT) subjects. INTERVENTIONS: Four random experimental sessions: relaxation (RX-20 min); exercise [EX-cycle ergometer, 53 min, 50% peak oxygen uptake (VO2peak)]; exercise plus relaxation (EX+RX); and control (C-73 min rest). Measures were taken before and after interventions at baseline and during Stroop color test. MAIN OUTCOME MEASURES: Auscultatory and plesthysmographic BPs. RESULTS: Systolic and diastolic BPs decreased significantly after all the interventions. The decreases in both BPs were significantly greater after the EX+RX session, and were also greater in the HT (EX+RX session, -10+/-1/-7+/-1 and -15+/-2/-8+/-1 mm Hg for the NT and HT, respectively). During mental stress, systolic BP increased significantly and similarly after all the experimental sessions. Diastolic BP also increased significantly during stress; however, the increase was significantly greater after the RX session. At the end of the mental stress, diastolic BP was significantly lower after the EX (74+/-3 mm Hg) and EX+RX (72+/-3 mm Hg) sessions than after the C (79+/-3 mm Hg) and RX (78+/-3 mm Hg) sessions. CONCLUSIONS: In NT and HT subjects, a single bout of exercise or relaxation has hypotensive effects, further enhanced by their combination, and greater in the HT. Moreover, exercise performed alone or in combination with relaxation decreases systolic and diastolic BPs during mental stress.     

肾动态显像评价肾积水患者肾功能的应用价值

目的 探讨肾动态显像Gates法测定肾小球滤过率（GFR）（gGFR）在肾积水和非肾积水肾病中的应用价值。 方法 选取2015年1月至2017年1月同时接受双血浆法测定GFR（rGFR）和gGFR的肾积水患者和非肾积水肾病患者,肾积水患者191例,其中男性97例、女性94例,年龄（43.35±15.91）岁;非肾积水肾病患者133例,其中男性82例、女性51例,年龄（55.31±13.54）岁。参照美国慢性肾脏病及透析的临床实践指南,将肾积水患者和非肾积水肾病患者分别分为肾功能正常组和轻、中、重度慢性肾衰竭组,对每组gGFR和rGFR进行分析比较,并计算两种方法的差值（ΔGFR）。不同肾功能组的比较采用单因素方差分析（ANOVA）,若差异有统计学意义,则行LSD-t检验法进行两两比较。gGFR和rGFR的比较采用配对t检验;相关性采用Pearson相关分析;一致性分析用Bland-Altman检验。 结果 肾积水和非肾积水肾病患者的gGFR比rGFR高,且前者的差异有统计学意义[（70.60±22.58） mL/（1.73 m2·min） vs. （58.67±20.49） mL/（1.73 m2·min）,t=9.335,P=0.000];与非肾积水肾病患者比较,肾积水患者gGFR和rGFR的相关性（r=0.692,P=0.000）较低。在肾积水患者中,轻、中、重度慢性肾衰竭组的gGFR均明显高于rGFR[（81.01±18.40） mL/（1.73 m2·min） vs. （71.03±7.74） mL/（1.73 m2·min）、（60.98±18.28） mL/（1.73 m2·min） vs. （45.85±7.60） mL/（1.73 m2·min）、（42.88±16.14） mL/（1.73 m2·min） vs. （23.65±4.04） mL/（1.73 m2·min）],差异均有统计学意义（t=4.559、8.398、4.480,均P<0.05）;中度慢性肾衰竭组gGFR和rGFR的相关性（r=0.461,P=0.000）最高;肾功能正常组和轻、中、重度慢性肾衰竭组患者的ΔGFR逐渐增高,分别为（?1.61±14.05）、（9.99±18.81）、（15.14±16.54）、（19.23±15.48）mL/（1.73 m2·min）,差异有统计学意义（F=5.595,P=0.001）; 有5.76%（11/191,>5%）的点在一致性界限（L_OA）之外,gGFR和rGFR的一致性较差。在非肾积水肾病患者中,轻度慢性肾衰竭组的gGFR明显低于rGFR[（66.08±8.97） mL/（1.73 m2·min） vs. （70.59±8.08） mL/（1.73 m2·min）],差异有统计学意义（t=?3.472,P<0.05）,中、重度慢性肾衰竭组的gGFR高于rGFR[（45.99±9.76） mL/（1.73 m2·min） vs. （43.83±8.29） mL/（1.73 m2·min）、（26.25±8.57） mL/（1.73 m2·min）vs.（20.19±5.72） mL/（1.73 m2·min）],差异均有统计学意义（t=2.095、4.907,均P<0.05）;轻度慢性肾衰竭组gGFR和rGFR的相关性（r=0.737,P=0.000）最高;肾功能正常组和轻、中、重度慢性肾衰竭组患者的ΔGFR逐渐增高,分别为（?5.64±16.64）、（?4.51±6.23）、（2.16±7.71）、（6.06±6.87）mL/（1.73 m2·min）,差异有统计学意义（F=9.446,P=0.000）;有3.01%（4/133,<5%）的点在L_OA之外,gGFR和rGFR的一致性较好。 结论 肾动态显像Gates法评估肾积水患者的GFR价值有限,应参考双血浆法的定量结果和其他检查结果进行综合分析判断。     

Effects of short-term endurance training on aortic distensibility in young males

BACKGROUND: Short-term endurance exercise training can increase aortic distensibility. The effect of exercise on arterial distensibility, however, may not last long term. PURPOSE: We evaluated the effects of short-term exercise training and detraining on aortic distensibility in 10 sedentary young males (21.0 +/- 0.6 yr, mean +/- SE; range 19-24 yr). METHODS: The subjects underwent 8 wk of endurance training on a cycle ergometer at 70% of maximal oxygen consumption (VO(2max)), for 60 min at a time and on alternate days (3-4 d.wk(-1). The detraining period consisted of a return to sedentary days for 8 wk. The aortic pulse wave velocity (APWV) was measured before and immediately after training and during the detraining period. RESULTS: The VO(2max) was significantly increased after training (pre: 2240.0 +/- 71.4 mL, after: 2728.8 +/- 82.5 mL, mean +/- SE, P < 0.0001) and remained at increased levels during the detraining period (after 4 wk: 2671.2 +/- 73.6 mL, P < 0.001; after 8 wk: 2628.0 +/- 85.0 mL, P < 0.001). The APWV was significantly decreased after training (pre: 5.80 +/- 0.15 m.s(-1), after: 5.50 +/- 0.21 m.s(-1), P < 0.01) but returned close to the baseline after detraining for 4 wk (5.66 +/- 0.13 m.s, P < 0.18). CONCLUSION: Our data suggest that short-term exercise training can improve aortic distensibility, but the effect cannot be maintained without continuing physical exercise.