Relationship of Thyroid Function with Renal Hemodynamics and Cholesterol Metabolism in Proteinuric Kidney Disease: A Pilot Study.

Nephrotic syndrome and hypothyroidism are respectively reported to influence renal hemodynamics and hypercholesterolemia. However, the relationship of proteinuria-associated thyroid function with renal hemodynamics and cholesterol metabolism has yet to be determined in a simultaneous analysis of thyroid, renal, and cholesterol variables. We investigated the hypothesis that the changes in thyroid hormones by proteinuria may contribute to changes in cholesterol metabolism and renal hemodynamics by proteinuria. Twenty-nine patients (17 men and 12 women) with proteinuric kidney disease (mean age 46 years) were enrolled in a pilot study. Data for serum free triiodothyronine (FT3), free thyroxine (FT4), total cholesterol, and filtration fraction (FF; assessed by para-aminohippuric acid clearance) were used in variable-adjusted correlation analyses. The patients had the following data (mean ± standard deviation): urinary protein 5.18 ± 3.28 g/day, FT3 2.18 ± 0.44 pg/mL, FT4 1.03 ± 0.26 ng/dL, FF 0.27 ± 0.07, and total cholesterol 327 ± 127 mg/dL. There was a significant positive correlation of FT3 with FF (ß = 0.58, p = 0.01) and a significant inverse correlation of FT4 with total cholesterol (ß = -0.40, p = 0.01). A positive correlation of FT3 with FF and an inverse correlation of FT4 with total cholesterol were demonstrated in patients with proteinuric kidney disease. The proteinuria-associated reduction in serum thyroid hormone levels was correlated with hypercholesterolemia and the reduced glomerular FF. Further studies of these relationships are required.

Adenosine reuptake inhibition reduces diabetes-induced glomerular hyperfiltration via the adenosine A2a receptor.

Diabetes-induced glomerular hyperfiltration is an early alteration in kidney function in diabetes. Previous studies have shown that reduced adenosine A2a receptor signaling contributes to diabetes-induced glomerular hyperfiltration. The present study investigated the effects of enhanced interstitial adenosine concentration by inhibition of cellular adenosine reuptake, thereby promoting endogenous adenosine signaling. Insulinopenic diabetes was induced by streptozotocin in adult male Sprague-Dawley rats. Two weeks after diabetes induction, kidney function in terms of glomerular filtration rate, and total, cortical, and medullary renal blood flows were evaluated under thiobutabarbital anesthesia during baseline and after renal artery infusion of two doses of the adenosine reuptake inhibitor dilazep. Dilazep did not affect mean arterial pressure indicating that the effects of the interventions were intrarenal. Diabetics had increased glomerular filtration rate compared with controls and dilazep dose-dependently decreased glomerular filtration rate in diabetics, whereas it had no significant effect in controls. Dilazep increased cortical renal blood flows in controls, whereas medullary blood flow was not significantly changed. Dilazep did not affect total renal blood flow in any of the groups but decreased cortical blood flow in diabetics, resulting in decreased filtration fraction by dilazep in diabetics. Pretreatment with the adenosine A2a antagonist ZM241385 prevented intrarenal dilazep-mediated effects on glomerular filtration rate and filtration fraction in diabetics. In conclusion, enhancing intrarenal adenosine signaling by dilazep normalizes diabetes-induced glomerular hyperfiltration at least in part by activation of adenosine A2a receptors.

Membrane-based therapeutic plasma exchange: Proposed techniques for preventing filter failure.

BACKGROUND AND OBJECTIVES: Therapeutic plasma exchange (TPE) is commonly performed using membrane-based TPE (mTPE) and is prone to filter failure. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We report on 46 patients, with a total of 321 mTPE treatments using the NxStage machine. This was a retrospective study with an aim to evaluate the effect of heparin, pre-filter saline dilution and the impact of total plasma volume exchanged (< 3 L vs. ≥3 L) on the rate of filter failure. Primary outcome was the overall rate of filter failure. Secondary outcomes included factors that may have indirectly influenced the rate of filter failure, including hematocrit, platelet count, replacement fluid (Fresh Frozen Plasma vs. albumin), and access type. RESULTS: We found that treatments that received both pre-filter heparin and saline had a statistically significant decrease in filter failure rate as compared to those that received neither (28.6% vs. 5.3%, P = .001), and compared to the treatments that received pre-filter heparin alone (14.2% vs. 5.3%, P = .015). In treatments that received both pre-filter heparin and saline predilution, we noted a significantly higher filter failure rate when the plasma volume exchanged was ≥3 L as compared to those that had <3 L exchanged (12.2% vs. 0.9%, P = .001). CONCLUSIONS: Rate of filter failure in mTPE can be reduced by implementing several therapeutic interventions including pre-filter heparin and pre-filter saline solution. These interventions were not associated with any clinically significant adverse events. Despite the above-mentioned interventions, large plasma volume exchanges of ≥3 L can negatively impact filter life.

Membrane-based therapeutic plasma exchange: Hemodynamics and operational characteristics leading to procedure failure.

BACKGROUND AND OBJECTIVES: Therapeutic plasma exchange (TPE) is a blood purification treatment capable of removing large molecular weight substances from plasma. It is commonly used for the removal of circulating pathogenic immunoglobulins presumed to be the cause of many autoimmune diseases. TPE can be performed with a membrane-based system (mTPE) or a centrifugal-based system (cTPE). When plasma separation is performed with a membrane, filter clotting can lead to longer treatment time, higher cost and can negatively impact patient satisfaction. In this study, we examine the operational characteristics that might influence filter life. DESIGN, SETTING, PARTICIPANTS, & MEASURES: We report on 24 patients, with a total of 135 mTPE treatments in a single tertiary care academic center using the NxStage machine. The study focuses on treatment specific parameters that may lead to procedure failure. The main parameters of interest were transmembrane pressure (TMP) and the filtration fraction as displayed on the machine (FFd) compared to the calculated filtration fraction (FFc). Primary outcome was to measure whether TMP, FFc, and FFd influenced filter survival. Secondary outcomes included factors that might have indirectly resulted in filter failure, including hematocrit (Hct), platelet count, heparin use, and intra-treatment calcium administration. RESULTS: In this study, we demonstrated that machine displayed filtration fractions (FFd) were lower than FFc and this difference was significantly larger in TPE sessions that experienced a clotting event (7.58 vs 6.22, P = .031). TPE sessions that clotted had a higher mean TMP (57.48 mmHg vs 44.43 mmHg, P = .001) and clotting events tended to have a lower mean blood flow rate (175.83 mL/min vs 189.55 mL/min, P = .002). In TPE sessions that received prefilter calcium administration, a higher mean dose of calcium gluconate was found in the sessions that experienced clotting (3.27 g vs 2.70 g, P = .013). Patients who experienced at least one clotting event were noted to be heavier than those patients without any clotting events (91.52 kg vs 72.15 kg, P = .040). Prefilter heparin administration was not associated with a lower incidence of filter clotting. We did not find a statistically significant difference in clotting events based upon type of intravenous access, pretreatment hematocrit, or pretreatment platelet counts. CONCLUSION: Among patients undergoing mTPE, machine FFd on the NxStage system are consistently lower than FFc. Treatments where there was a greater difference between displayed and FFc had a greater likelihood of filter clotting. Treatments with higher TMP were associated with failed treatments. Prefilter calcium administration during treatment was associated with increased filter clotting. Lower blood flow rates and higher patient weight were also associated with increased filter clotting. Prefilter heparin administration did not reduce the incidence of filter clotting.

Determining factors for hemodiafiltration to equal or exceed the performance of expanded hemodialysis.

The aim of the study was to compare expanded hemodialysis (HDx) with hemodiafiltration (HDF) at different infusion flows to identify the main determinants, namely blood flow (Qb), replacement volume, infusion flow (Qi), ultrafiltration flow (Quf ), filtration fraction (FF), and the point at which the effectiveness of HDF equals or exceeds that of HDx. We conducted a prospective, single-center study in 12 patients. Each patient underwent 12 dialysis sessions: six sessions with Qb 350 and six with Qb 400 mL/min; with each Qb, one session was with HDx and five sessions were with FX80 (one in HD, and four with Qi 50, 75, 90/100 mL/min or autosubstitution in postdilution HDF). The reduction ratios (RR) of urea, creatinine, ß2 -microglobulin, myoglobin, prolactin, α1 -microglobulin, α1 -acid glycoprotein, and albumin were compared intraindividually and the global removal score (GRS) was calculated. The mean replacement volume with Qb 350 mL/min was 13.77 ± 0.92 L with Qi 50 mL/min, 20.75 ± 1.17 L with Qi 75, 23.83 ± 1.92 L with Qi 90, and 27.51 ± 2.77 L with autosubstitution. Similar results were obtained with Qb 400 mL/min, and the results were only slightly higher with Qi 100 mL/min or in autosubstitution. The GRS was positively correlated with replacement volume with Qb 350 (R2  = 0.583) and with Qb 400 (R2  = 0.584); with Quf with Qb 350 (R2  = 0.556) and with Qb 400 (R2  = 0.604); and also with FF with Qb 350 (R2  = 0.556) and with Qb 400 mL/min (R2  = 0.603). The minimum convective volume in HDF from which it is possible to overcome the efficacy of HDx was 19.2 L with Qb 350 and 17.6 L with Qb 400 mL/min. The cut-off point of Quf at which HDF exceeded the effectiveness of HDx was 80.6 mL/min with Qb 350 and 74.1 mL/min with Qb 400 mL/min. The cut-off point at which FF in HDF exceeded the effectiveness of the HDx was 23.0% with Qb 350 and 18.6% with Qb 400 mL/min. In conclusion, this study confirms the superiority of postdilution HDF over HDx when replacement volume, convective volume, Quf , or FF exceeds certain values. Increasing the Qb in postdilution HDF manages to increase the convective dose and more easily overcome the HDx.

Value of the Filtration Fraction Assessed by Dynamic 99mTc-Diethylenetriaminepentaacetic Acid Renal Scintigraphy After Angiotensin-Converting Enzyme Inhibition for the Diagnosis of Renovascular Hypertension.

PURPOSE: This study aimed to determine the diagnostic value of the relative filtration fraction (RFF) assessed by dynamic 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA) renal scintigraphy after angiotensin-converting enzyme (ACE) inhibition for renovascular hypertension (RVHT) diagnosis. METHODS: 99mTc-DTPA captopril renal scintigraphy performed in adolescents or adults (≥ 10 years) with suspected RVHT was retrospectively reviewed. The RFF of the affected kidney was qualitatively assessed as the relative glomerular filtration rate during the 2 to 3-min period compared with the relative perfusion during the first 60 s (qualitative RFF) and scored from 1 (definitely same) to 5 (definitely decreased). The quantitative RFF of the affected kidney was obtained by dividing the percentage of glomerular filtration rate by the percentage of renal perfusion. RESULTS: Overall, 173 patients (high probability, n = 15; and low probability, n = 158) were included based on conventional captopril renal scintigraphic criteria. An abnormal qualitative RFF was observed in 12 patients with high probability, and the diagnostic sensitivity was 80.0% (95% CI, 51.9-95.7). The RFF was normal in 152 patients with low probability, and the diagnostic specificity was 96.2% (95% CI, 91.9-98.6). The RFF was lower in patients with high probability than in those with low probability (0.79 ± 0.15 vs. 1.02 ± 0.11, P < 0.0001). CONCLUSIONS: The RFF assessed by dynamic 99mTc-DTPA renal scintigraphy after ACE inhibition can detect patients with high probability for RVHT. The RFF after ACE inhibition might be a useful diagnostic criterion especially when baseline scintigraphy is not available for evaluating ACE inhibition-induced changes.

Biochemical Markers of Renal Hypoperfusion, Hemoconcentration, and Proteinuria after Extreme Physical Exercise.

Background and Objectives: Physical exercise increases the blood perfusion of muscles, but decreases the renal blood flow. There are several markers of renal hypoperfusion which are used in the differential diagnosis of acute kidney failure. Albuminuria is observed after almost any exercise. The aim of this study was to assess changes in renal hypoperfusion and albuminuria after a 100-km race. Materials and Methods: A total of 27 males who finished a 100-km run were studied. The mean age of the runners was 38.04 ± 5.64 years. The exclusion criteria were a history of kidney disease, glomerular filtration rate (GFR) <60 ml/min, and proteinuria. Blood and urine were collected before and after the race. The urinary albumin/creatinine ratio (ACR), fractional excretion of urea (FeUrea) and sodium (FeNa), plasma urea/creatinine ratio (sUrea/Cr), urine/plasma creatinine ratio (u/pCr), urinary sodium to potassium ratio (uNa/K), and urinary potassium to urinary potassium plus sodium ratio (uK/(K+Na)) were calculated. Results: After the race, significant changes in albuminuria and markers of renal hypoperfusion (FeNa, FeUrea, sUrea/Cr, u/sCr, urinary Na, uNa/K, uK/(K+Na)) were found. Fifteen runners (55.56%) had severe renal hypoperfusion (FeUrea <35, uNa/K <1, and uK/(Na+K) >0.5) after the race. The mean ACR increased from 6.28 ± 3.84 mg/g to 48.43 ± 51.64 mg/g (p < 0.001). The ACR was higher in the group with severe renal hypoperfusion (59.42 ± 59.86 vs. 34.68 ± 37.04 mg/g), but without statistical significance. Conclusions: More than 50% of the runners had severe renal hypoperfusion after extreme exercise. Changes in renal hemodynamics are probably an important, but not the only, factor of post-exercise proteinuria.

Acute intrarenal angiotensin (1-7) infusion decreases diabetes-induced glomerular hyperfiltration but increases kidney oxygen consumption in the rat.

AIM: Common kidney alterations early after the onset of insulinopenic diabetes include glomerular hyperfiltration, increased oxygen consumption and tissue hypoxia. Increased activity of the renin-angiotensin-aldosterone system (RAAS) has been implicated in most of these early alterations. The RAAS peptide angiotensin (1-7) has the potential to modulate RAAS-mediated alterations in kidney function. Thus, the aim of the present study was to determine the acute effects of angiotensin (1-7) in the kidney of insulinopenic type 1 diabetic rat and the results compared to that of normoglycaemic controls. METHODS: Renal haemodynamics and oxygen homeostasis were measured 3 weeks after administration of streptozotocin before and after acute intrarenal infusion of angiotensin (1-7) at a dose of 400 ng min-1 . RESULTS: Arterial pressure and renal blood flow were similar between groups and not affected by exogenous angiotensin (1-7). Diabetics presented with glomerular hyperfiltration, increased urinary sodium excretion and elevated kidney oxygen consumption. Angiotensin (1-7) infusion normalized glomerular filtration, increased urinary sodium excretion, decreased proximal tubular reabsorption, and elevated kidney oxygen consumption even further. The latter resulting in tubular electrolyte transport inefficiency. Angiotensin (1-7) did not affect tissue oxygen tension and had no significant effects in controls on any of the measured parameters. CONCLUSION: Diabetes results in increased responsiveness to elevated levels of angiotensin (1-7) which is manifested as inhibition of tubular sodium transport and normalization of glomerular filtration. Furthermore, elevated angiotensin (1-7) levels increase kidney oxygen consumption in the diabetic kidney even further which affects tubular electrolyte transport efficiency negatively.

Value of the Filtration Fraction Assessed by Dynamic ⁹⁹mTc-Diethylenetriaminepentaacetic Acid Renal Scintigraphy After Angiotensin-Converting Enzyme Inhibition for the Diagnosis of Renovascular Hypertension / 대한핵의학회잡지

PURPOSE: This study aimed to determine the diagnostic value of the relative filtration fraction (RFF) assessed by dynamic ⁹⁹mTc-diethylenetriaminepentaacetic acid (⁹⁹mTc-DTPA) renal scintigraphy after angiotensin-converting enzyme (ACE) inhibition for renovascular hypertension (RVHT) diagnosis.METHODS: ⁹⁹mTc-DTPA captopril renal scintigraphy performed in adolescents or adults (≥ 10 years) with suspected RVHT was retrospectively reviewed. The RFF of the affected kidney was qualitatively assessed as the relative glomerular filtration rate during the 2 to 3-min period compared with the relative perfusion during the first 60 s (qualitative RFF) and scored from 1 (definitely same) to 5 (definitely decreased). The quantitative RFF of the affected kidney was obtained by dividing the percentage of glomerular filtration rate by the percentage of renal perfusion.RESULTS: Overall, 173 patients (high probability, n = 15; and low probability, n = 158) were included based on conventional captopril renal scintigraphic criteria. An abnormal qualitative RFF was observed in 12 patients with high probability, and the diagnostic sensitivity was 80.0% (95% CI, 51.9–95.7). The RFF was normal in 152 patients with low probability, and the diagnostic specificity was 96.2% (95% CI, 91.9–98.6). The RFF was lower in patients with high probability than in those with low probability (0.79 ± 0.15 vs. 1.02 ± 0.11, P < 0.0001).CONCLUSIONS: The RFF assessed by dynamic ⁹⁹mTc-DTPA renal scintigraphy after ACE inhibition can detect patients with high probability for RVHT. The RFF after ACE inhibition might be a useful diagnostic criterion especially when baseline scintigraphy is not available for evaluating ACE inhibition-induced changes.

Kidney Function Reserve Capacity in Early and Later Stage Autosomal Dominant Polycystic Kidney Disease.

BACKGROUND AND OBJECTIVES: It is assumed that in autosomal dominant polycystic kidney disease (ADPKD), kidney function remains in the normal range for several decades because of hyperfiltration of remnant nephrons. In this study, we investigate the extent to which patients with ADPKD hyperfilter. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In this cross-sectional study, we measured GFR as urinary clearance using continuous infusion of 125I-iothalamate. Kidney function reserve capacity was determined as increase in measured GFR after adding a dopamine infusion of 4.4-6 mg/h. Potential kidney donors were used as healthy controls and matched by age and sex to patients with ADPKD for comparisons across age groups and CKD stages. Hyperfiltration was defined by a loss of kidney function reserve capacity compared with healthy controls. RESULTS: A total of 300 participants were studied. In the youngest age group (18-29 years), measured GFR was not different between patients with ADPKD and healthy controls (103±21 versus 111±9 ml/min per 1.73 m2; P=0.14). In this age group kidney function reserve capacity was higher compared with healthy controls (11.1%±8.3% versus 5.3%±6.5%; P=0.04). Moreover, kidney function reserve capacity was similar to healthy controls in patients with ADPKD with early-stage disease (eGFR≥60 ml/min per 1.73 m2), either overall or when divided into fast or slow progressors according to their Mayo height-adjusted total kidney volume class. However, in patients with ADPKD, lower measured GFR was associated with lower kidney function reserve capacity (ß=1.0 [95% confidence interval, 0.5 to 1.5] % per 10 ml/min per 1.73 m2; P<0.001). Kidney function reserve capacity was therefore lower compared with healthy controls at older age and later CKD stages. CONCLUSIONS: Patients with early-stage ADPKD, either classified as having rapidly or slowly progressive disease, are able to increase their GFR in response to dopamine. Hyperfiltration, defined by a loss of kidney function reserve capacity, may therefore not be an early phenomenon in ADPKD.

Usefulness of gel filtration fraction as potential biomarker for neurocysticercosis in serum: towards a new diagnostic tool.

There is an increasing interest in improving neurocysticercosis (NCC) diagnosis through the search of new and alternative antigenic sources, as those obtained from heterologous antigens. The aim of this study was to obtain potential biomarkers for NCC diagnosis after gel filtration chromatography [gel filtration fraction (GFF)] from the total saline extract (SE) from Taenia saginata metacestodes, followed by protein identification and application in immunodiagnostic. SE and GFF proteic profiles were characterized in gel electrophoresis, and diagnostic performance was verified by testing 160 serum samples through enzyme-linked immunosorbent assay and immunoblotting. Sensitivity (Se), specificity (Sp) and other diagnostic parameters were calculated. Polypeptides of interest in the diagnosis of human NCC present at GFF were analysed by mass spectrometry (MS) and B-cell epitopes were predicted. GFF had the best diagnostic parameters: Se 93·3%; Sp 93%; AUC 0·990; LR+ = 13·42 and LR- = 0·07, and proved to be useful reacting with serum samples in immunoblotting. Proteic profile ranged from 64 to 68 kDa and enolase and calcium binding protein calreticulin precursor were identified after MS. The enolase and calcium-binding protein calreticulin precursor showed 18 and 10 predicted B-cell epitopes, respectively. In conclusion we identified important markers in the GFF with high efficiency to diagnose NCC.

Significance of renal filtration fraction evaluation of renal artery stenting for atherosclerotic renal artery stenosis treatment / 北京大学学报(医学版)

Objective:To investigate the significance of filtration fraction (FF) and renal artery stenting in the treatment of atherosclerotic renal artery stenosis.Methods:In the study,42 cases of renal artery stenosis were treated with 52 renal artery stent implantation.Percutaneous transluminal renal angioplasty and stent (PTRAS) of the patients' health side kidney,ipsilateral kidney (renal) glomerular filtration rate (GFR),renal effective renal plasma flow effective renal plasma flow (ERPF),kidney filtration fraction changes of preoperative and postoperative serum creatinine (SCR) and the changes in the patients with blood pressure (SBP) and the changes after taking antihypertensive drugs were observed and analyzed.Results:The 52 cases of renal artery stent implantation were all successful.Preoperative ipsilateral GFR was significantly lower than that of normal side (t =-3.989,P =0.000);preoperative ipsilateral ERPF was significantly lower than the contralateral side (t =-4.926,P =0.000).On both sides,the overall FF values were equal (t =1.273,P =O.207).Postoperative ipsilateral renal GFR was increased,but there was no statistical difference (t =-1.411,P =0.164).Postoperative ipsilateral renal ERPF was increased significantly (t =-4.954,P =0.000),and FF lower (closer to the normal value (t =3.274,P =0.002).Postoperative side GFR was significantly reduced (t =2.569,P =0.000),the contralateral ERPF was significantly reduced (t =3.889,P =0.001),and FF had no significant change (t =-0.758,P =0.454).Postoperative side GFR was lower than that of the contralateral (t =-3.283,P =0.002) and postoperative side ERPF was still lower than that of the contralateral (t =-3.351,P =0.001),but on both sides,the FF values were equal (t =-0.361,P =0.719).Preoperative FF was relatively normal in the patients with kidney,and the postoperative FF value change was small (t =O.799,P =O.430);preoperative FF was significantly higher in the patients with kidney,and the postoperative FF value was lower than the preoperative (normal value,t =5.299,P =0.000).Postoperative overall serum creatinine was significantly decreased (t =2.505,P =0.016);but for the patients with unilateral renal artery stenosis,the changes in serum creatinine had no statistical difference (t =1.228,P =0.299);and for the patients with bilateral renal artery stenosis and serum creatinine compared with the preoperative,the changes were decreased significantly (t =2.518,P =0.030);postoperative blood pressure (SBP) was significantly decreased compared with that before operation (t =8.945,P =0.000);antihypertensive drugs taken were decreased significantly compared with the preoperative (t =5.280,P =0.000).Conclusion:For the patients with renal artery stenosis,FF is a useful index to understand the pathophysiological process of renal ischemia.Whether preoperative FF is significantly increased or FF is relatively normal,should be regarded as the indications of renal artery stent implantation.

Dialysis and Patient Factors Which Determine Convective Volume Exchange in Patients Treated by Postdilution Online Hemodiafiltration.

Recent reports suggest a survival advantage for dialysis patients treated by postdilutional online hemodiafiltration (OL-HDF) who achieve higher volume convective exchanges. As such, the factors associated with achieving higher convective volume exchange were determined. The convective exchange volumes during the midweek OL-HDF session in a cohort of 653 patients with corresponding bio-impedance measurements of volume status and sessional electronic records were audited. Mean patient age was 64.9 ± 14.9 years, 65.3% male, 47.7% diabetes, with 81.6% dialyzing using fistula access. Sessional substitution volume exchanged was 17.0 ± 3.5 L (83.8 ± 13.9 mL/min), with a filtration fraction of 23.3 ± 4.6%, sessional time of 3.8 ± 0.5 h, and blood flow 321 ± 28 mL/min. As expected, convection exchange volume achieved was associated with sessional time (ß 3.24, P < 0.001), blood flow (ß 0.03, P < 0.001), dialysate flow (ß 0.03, P < 0.001), but also patient factors: postsessional intracellular water (ICW) (ß 0.07, P = 0.002), and serum albumin (ß 0.71, P = 0.011). In addition convective exchange was lower for diabetics (16.6 ± 3.0 vs. 17.3 ± 3.8 L, P < 0.01), and for patients with higher Davies co-morbidity grades (16.6 ± 2.8 vs. 17.0 ± 3.6 vs. 17.9 ± 4.0 L), P = 0.01 respectively. As expected the convective volume exchanged with OL-HDF was associated with sessional time and blood and dialysate flows. However, the convective volume exchange achieved was also associated with patient factors, including ICW, which is related to body cell mass and also co-morbidity. Although some center practices can be modified to increase convective exchange, patient factors are not so readily remediable. As such, highly comorbid patients may not be able to achieve the higher volume convective exchanges reported to be associated with improved patient survival.

Circuit life versus bleeding risk: the impact of achieved activated partial thromboplastin time versus achieved filtration fraction.

Whilst prolonging hemofilter (circuit) life, heparin increases bleeding risk. The impact of achieved activated partial thromboplastin time (APTT) on circuit life and bleeding risk has not been assessed in a modern critically ill cohort. Lowering filtration fraction may be an alternative means of prolonging circuit life, but is often overlooked in critical care. An observational study of 309 consecutive circuits in a general intensive care unit was conducted using a wide target APTT range. Multilevel modeling was used to predict circuit life and bleeding according to achieved APTT and filtration fraction. Independent predictors of circuit failure (i.e. unplanned ending of treatment) included filtration fraction (P<0.001, HR 1.07 per 1% increase), peak APTT (P<0.001, HR 0.8 per 10 s increase or 0.3 APTR increase) and baseline PT (P=0.014, HR 0.91 for every 50% increase). The only significant predictor of bleeding was peak APTT (P=0.017, OR 1.05 per 10 s increase). Every 10 s APTT increase was associated with a 20% reduction in circuit failure, but a 5% increase in hemorrhage. A 3% reduction in filtration fraction was associated with the same improvement in circuit life as a 10 s increase in APTT. Increasing APTT prolongs circuit life but carries a substantial risk of bleeding even in modern practice. Filtration fraction has a large impact on circuit life in the critically ill: a 3% reduction in filtration fraction, e.g. by increasing blood flow or delivering some of the clearance via dialysis, would be expected to reduce circuit failure as much as a 10 s increase in APTT.

Estimation of single-kidney glomerular filtration rate without exogenous contrast agent.

PURPOSE: Measurement of single-kidney filtration fraction and glomerular filtration rate (GFR) without exogenous contrast is clinically important to assess renal function and pathophysiology, especially for patients with comprised renal function. The objective of this study is to develop a novel MR-based tool for noninvasive quantification of renal function using conventional MR arterial spin labeling water as endogenous tracer. THEORY AND METHODS: The regional differentiation of the arterial spin labeling water between the glomerular capsular space and the renal parenchyma was characterized and measured according to their MR relaxation properties (T1ρ or T2 ), and applied to the estimation of filtration fraction and single-kidney GFR. The proposed approach was tested to quantify GFR in healthy volunteers at baseline and after a protein-loading challenge. RESULTS: Biexponential decay of the cortical arterial spin labeling water MR signal was observed. The major component decays the same as parenchyma water; the minor component decays much slower as expected from glomerular ultra-filtrates. The mean single-kidney GFR was estimated to be 49 ± 9 mL/min at baseline and increased by 28% after a protein-loading challenge. CONCLUSION: We developed an arterial spin labeling-based MR imaging method that allows us to estimate renal filtration fraction and singe-kidney GFR without use of exogenous contrast.

Defensas antioxidantes en la insuficiencia renal crónica experimental / Antioxidant defenses in the experimental chronic renal failure

OBJETIVO: Evaluar el comportamiento de las defensas antioxidantes en relación con las modificaciones funcionales progresivas en la insuficiencia renal crónica experimental. MÉTODOS: Estudio experimental controlado en 40 ratas Wistar provocando insuficiencia renal por ablación de 5/6 de la masa renal. La muestra se dividió en 4 grupos de 10 animales, 1 grupo control y 3 experimentales (E) sometidos a extirpación del riñón derecho y ligadura de dos ramas de la arteria renal izquierda. El grupo experimental E-I evolucionó 2 sem después de la nefrectomía, el grupo E-II 4 sem y el grupo E-III durante 6 semanas. Se realizó aclaramiento plasmático de ácido paraminohipúrico (PAH) e inulina (I) para medir flujo plasmático renal efectivo (FPR) e intensidad de filtración glomerular (IFG) respectivamente. Los cambios de IFG y FPR permitieron constatar las modificaciones funcionales a medida que progresaba la insuficiencia renal. Los indicadores de defensa antioxidante incluyeron la actividad de la enzima superóxido dismutasa (SOD) y los niveles de glutatión reducido (GSH), medidos en homogenado de riñón. Se realizó análisis de regresión lineal para relacionar cambios funcionales y defensas antioxidantes. RESULTADOS: La función renal decreció progresivamente después de la nefrectomía. Se produjo disminución de la actividad de la SOD seguida de una superinducción a las 6 semanas y los niveles de GSH comenzaron a disminuir en la 4ta. sem posnefrectomía. CONCLUSIONES: Los cambios en los indicadores de defensa antioxidante a nivel renal sugieren que el estrés oxidativo aumenta en el órgano correlacionßndose con la pérdida progresiva de la función renal

OBJECTIVE: to evaluate the changes on antioxidant defenses in kidneys while function changes on remaining tissue during progression of renal failure after performing subtotal nephrectomy. METHODS: an experimental trial in 40 Wistar rats was done. The renal failure was induced by surgical ablation of 5/6 of the renal mass, removing the right kidney and tying two branches of the left renal artery to 30 rats; 3 study groups were formed and followed over a period of 2, 4, and 6 weeks. The remaining group of rats was used as control. Functional remainder state was evaluated by measurement of the Glomerular Filtration Rate (GFR) and effective Renal Plasmatic Flow (RPF), through renal plasmatic clearance methods. Measurement of reduced glutathione (GSH) and superoxide dismutase activity (SOD) in renal mass were used as markers of antioxidant defense. Lineal correlation was used to analyze correlations between progressive functional changes and oxidative status. RESULTS: Progressive decreasing of both GFR and RPF were noted. SOD activity diminished initially followed by a super induction at 6th week and GSH levels decreased markedly at 4th week after nephrectomy. CONCLUSION: The variations of antioxidant defenses markers on renal tissue suggest that oxidative stress increases in the remainder kidney correlated to the progressive reduction of the renal function

Defensas antioxidantes en la insuficiencia renal crónica experimental / Antioxidant defenses in the experimental chronic renal failure

OBJETIVO: Evaluar el comportamiento de las defensas antioxidantes en relación con las modificaciones funcionales progresivas en la insuficiencia renal crónica experimental. MÉTODOS: Estudio experimental controlado en 40 ratas Wistar provocando insuficiencia renal por ablación de 5/6 de la masa renal. La muestra se dividió en 4 grupos de 10 animales, 1 grupo control y 3 experimentales (E) sometidos a extirpación del riñón derecho y ligadura de dos ramas de la arteria renal izquierda. El grupo experimental E-I evolucionó 2 sem después de la nefrectomía, el grupo E-II 4 sem y el grupo E-III durante 6 sem. Se realizó aclaramiento plasmático de ácido paraminohipúrico (PAH) e inulina (I) para medir flujo plasmático renal efectivo (FPR) e intensidad de filtración glomerular (IFG) respectivamente. Los cambios de IFG y FPR permitieron constatar las modificaciones funcionales a medida que progresaba la insuficiencia renal. Los indicadores de defensa antioxidante incluyeron la actividad de la enzima superóxido dismutasa (SOD) y los niveles de glutatión reducido (GSH), medidos en homogenado de riñón. Se realizó análisis de regresión lineal para relacionar cambios funcionales y defensas antioxidantes. RESULTADOS: La función renal decreció progresivamente después de la nefrectomía. Se produjo disminución de la actividad de la SOD seguida de una superinducción a las 6 semanas y los niveles de GSH comenzaron a disminuir en la 4ta. sem posnefrectomía. CONCLUSIONES: Los cambios en los indicadores de defensa antioxidante a nivel renal sugieren que el estrés oxidativo aumenta en el órgano correlacionándose con la pérdida progresiva de la función renal(AU)

OBJECTIVE: to evaluate the changes on antioxidant defenses in kidneys while function changes on remaining tissue during progression of renal failure after performing subtotal nephrectomy. METHODS: an experimental trial in 40 Wistar rats was done. The renal failure was induced by surgical ablation of 5/6 of the renal mass, removing the right kidney and tying two branches of the left renal artery to 30 rats; 3 study groups were formed and followed over a period of 2, 4, and 6 weeks. The remaining group of rats was used as control. Functional remainder state was evaluated by measurement of the Glomerular Filtration Rate (GFR) and effective Renal Plasmatic Flow (RPF), through renal plasmatic clearance methods. Measurement of reduced glutathione (GSH) and superoxide dismutase activity (SOD) in renal mass were used as markers of antioxidant defense. Lineal correlation was used to analyze correlations between progressive functional changes and oxidative status. RESULTS: Progressive decreasing of both GFR and RPF were noted. SOD activity diminished initially followed by a super induction at 6th week and GSH levels decreased markedly at 4th week after nephrectomy. CONCLUSION: The variations of antioxidant defenses markers on renal tissue suggest that oxidative stress increases in the remainder kidney correlated to the progressive reduction of the renal function(AU)