The impact of early normalization of haematocrit by erythropoietin on renal damage in the remnant kidney model

BACKGROUND: Correction of anaemia in moderate to advanced renal failure is still a matter of debate because of postulated detrimental effects of erythropoietin on the progression of renal damage. METHODS: The renal effects of early normalization of haematocrit (Htc) by erythropoietin (rHuEpo) were investigated from the time of 5/6 nephrectomy up to 8 weeks post-intervention in three groups of remnant kidney model rats: untreated controls (CON), rats receiving 100 UI/kg body-wt of rHuEpo i.p. twice a week (EPO), and rats receiving rHuEpo in which periodic phlebotomies maintained Htc similar to the value of the control group (PHL). The latter group was included to evaluate the direct effects of rHuEpo on renal damage, i.e. independent from Htc correction. RESULTS: Two weeks after renal ablation (basal), Htc decreased in CON and PHL rats (from 49.3+/-1.4% to 43.2+/- 1.1, P < 0.05 and from 49.6+/-1.1 to 43.3+/-1.5%, P<0.05 respectively), while it remained consistently normal in EPO rats (48.9+/-1.2% to 48.9+/-1.50/%, P<0.05 vs other groups). Thereafter Htc did not change throughout the remaining period in all groups. At the end of the study, with respect to basal, resting blood pressure increased significantly by the same extent in CON (+ 13+/-2%) and EPO rats (+ 15+/-5%), while it remained constant in PHL rats. Notably, creatinine clearance significantly decreased in CON (-53+/-8% 8 vs basal) and EPO (-38+/-8% vs basal), while it did not change in PHL rats. Likewise the degree of proteinuria as well as renal morphologic alterations and glomerular hypertrophy/sclerosis was similar in CON and EPO rats, and was significantly more severe than in the phlebotomized group. The only difference detected between CON and EPO group was the greater mesangial hypercellularity in rHuEpo-treated rats. CONCLUSION: In uraemic rats, chronic treatment with rHuEpo aimed at normalization of Htc beginning the early stage of renal failure does not inevitably account for a rise in systemic blood pressure. In addition, neither erythropoietin per se nor the correction of haematocrit accelerates the progression of renal damage when blood pressure remains constant.     

Unilateral nephrectomy in dogs with renal disease: 30 cases (1985-1994)

OBJECTIVE: To evaluate indications for and complications, efficacy, and effects on renal function of unilateral nephrectomy in dogs with renal disease, and to evaluate the role that scintigraphy had in the decision to excise a kidney. DESIGN: Retrospective case series. ANIMALS: 30 dogs with renal disease that underwent unilateral nephrectomy. A comparison group of 12 dogs with renal calculi that underwent renal scintigraphy but not nephrectomy was included. RESULTS: Indications for nephrectomy included renal or ureteral calculi (n = 10), renal mass (8), chronic pyelonephritis (5), perirenal mass (3), severe hydronephrosis and hydroureter (3), and renal hypoplasia with ureteral ectopia (1). None of the dogs were azotemic before surgery. Renal scintigraphy apparently influenced the decision to perform nephrectomy, because in 14 of 16 dogs that underwent nephrectomy, the affected kidney contributed < or = 33% of the total glomerular filtration rate, but in 6 of 8 comparison dogs that underwent nephrotomy, the affected kidney contributed > 33% of total glomerular filtration rate. Complications of nephrectomy included oliguria (5) and organ laceration (2). Mean +/- SD final serum creatinine concentration for 16 dogs alive at least 6 months after nephrectomy was 2.2 +/- 1.8 mg/dl. Three dogs had chronic renal failure of undetermined cause at the time of death. Nephrectomy did not completely resolve the underlying disease in 13 dogs. Renal function was evaluated in 6 dogs 2 to 3.5 years after nephrectomy and was impaired in 4. None of the dogs were anemic, azotemic, proteinuric, or hypertensive. Survival time varied depending on the underlying disease. CLINICAL IMPLICATIONS: Multiple factors contributed to the decision to perform nephrectomy. Unilateral nephrectomy resulted in few serious complications and was not detrimental to the remaining kidney, but did not always resolve the underlying disease.     

Parathyroidectomy does not prevent the renal PTH/PTHrP receptor down-regulation in uremic rats

In a recent study we demonstrated that the PTH/PTHrP receptor (PTH-R) mRNA was markedly down-regulated in the remnant kidney of uremic rats with severe secondary hyperparathyroidism. Among the factors potentially implicated in this down-regulation, to date only PTH has been demonstrated to modulate PTH-R expression. Here, we examined the effect of thyroparathyroidectomy (TPTX) on the renal expression of PTH-R in rats with normal renal function or with chronic renal failure (CRF) induced by 5/6 nephrectomy. Four groups of rats were studied: control, TPTX, CRF, and CRF + TPTX. Moderate-degree renal failure was documented by mean (+/- SD) creatinine clearances (microliter/min/100 g body wt) of 259 +/- 40 and 212 +/- 45 in CRF and CRF + TPTX rats, compared with 646 +/- 123 and 511 +/- 156 in control and TPTX rats, respectively. Plasma phosphorus, calcitriol, and ionized calcium were significantly lower in CRF and CRF + TPTX than in control animals. Plasma ionized calcium and calcitriol were also lower in TPTX than in control rats. Plasma PTH levels (pg/ml) were increased in CRF rats (41.8 +/- 29.4), and markedly decreased in TPTX (10.1 +/- 7.8) and CRF + TPTX (8.0 +/- 3.8) rats compared with control rats (21.7 +/- 7.5). Northern blot analysis showed that the level of the steady-state PTH-R mRNA in the kidney of CRF and CRF + TPTX rats was markedly decreased compared with that of control rats, the ratios of PTH-R mRNA/beta-actin mRNA being 0.28 +/- 0.04 and 0.27 +/- 0.03 versus 0.54 +/- 0.05, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Upregulation of atrial natriuretic peptide gene expression in remnant kidney of rats with reduced renal mass

Atrial natriuretic peptide (ANP) is synthesized in the kidney but its physiologic significance there is unclear. To determine whether renal expression of the ANP gene is regulated, renal ANP mRNA expression was assessed in remnant kidneys after 5/6 nephrectomy in Munich-Wistar rats. In normal sodium intake groups, ANP mRNA expression in the remnant kidney was significantly increased by 5.0 +/- 0.8-fold (n = 7, mean +/- SEM) at 4 d when compared with sham-operated controls (n = 6, all sham-operated groups) (*P < 0.001 by Scheffe's test) and by 28.3 +/- 5.1-fold at 14 d. This latter response was markedly diminished to 7.6 +/- 2.1-fold (n = 7, versus sham) in rats maintained on a low sodium diet. At 4 d, on the other hand, no significant downregulation was observed with dietary sodium restriction. Because natriuretic peptides have previously been shown by us to play a major role in the adaptive responses of remnant nephrons to renal mass ablation, these data suggest that ANP of renal origin may contribute to the overall mechanism for enhancing sodium excretion in the face of declining nephron number.     

Ouabain-containing Euro-Collins solution prevents ATN following renal cold storage

In view of the hypothesis that suppression of energy demand may prevent ischemic cell damage, it seemed possible that suppression of ATP utilization during ischemia might ameliorate the severity of renal failure following kidney preservation. To test this possibility, a short-term in situ kidney preservation model was prepared in dogs. Euro-Collins solution containing 10(-5) M ouabain (O-EC) was used as the preservation solution. The kidney was preserved with cold O-EC for two hours and reperfused with auto blood. As the control, the kidney was treated with Euro-Collins solution (EC) alone. Three hours after reperfusion, recovery of creatinine clearance was 47.4 +/- 8.0% in the control and 71.6 +/- 14.0% in the O-EC group (p < 0.02). The increase in urinary excretion of N-acetyl-beta-D-glucosaminidase was significantly lower in the O-EC group. It was 21.3 +/- 4.5 nU/gr renal weight for three hours after reperfusion in the control group and 7.2 +/- 1.5 nU/gr renal weight in the O-EC group (p < 0.05). Fractional excretion of sodium three hours after reperfusion was 1.42 +/- 0.44% and 5.51 +/- 0.63% in the control and O-EC groups (p < 0.002), respectively. There were no significant differences in renal blood flow, urine volume and urine osmolality between the two groups. These results suggest that ouabain-containing EC was effective in protecting the kidney, especially renal proximal tubular cell, against ischemic damage.     

BDNF-dependent enhancement of exocytosis in cultured cortical neurons requires translation but not transcription

PURPOSE: The surgical management of chronic atherosclerotic renal artery occlusion (RA-OCC) was studied. METHODS: From January 1987 through December 1996, 397 consecutive patients were treated for atherosclerotic renal artery disease. Ninety-five hypertensive patients (mean blood pressure, 204 +/- 31/106 +/- 20 mm Hg; mean medications, 3.0 +/- 1.1 drugs) were treated for 100 RA-OCCs. Eighty-four (88%) patients had renal dysfunction, defined by serum creatinine levels >/=1.3 mg/dL (mean serum creatinine level, 2.8 +/- 2.0 mg/dL). Demographic characteristics, operative morbidity and mortality, blood pressure/renal function response, and postoperative decline in renal function were examined and compared with that of 302 patients treated for renal artery stenosis (RAS). RESULTS: After operation, there were 5 perioperative deaths (5.2%), 2 (2.8%) after revascularization and 3 (12%) after nephrectomy (P =.11), compared with 12 (4.0%) perioperative deaths in the RAS group (P =.59). After controlling for important covariates, estimated survival and blood pressure benefits did not differ between RA-OCC patients treated by nephrectomy or revascularization (P =.13; 87% vs 92%, P =.54). Excretory renal function was considered improved in 49% of 79 RA-OCC patients with renal dysfunction, including 9 patients removed from dialysis-dependence. Among patients treated for unilateral disease, revascularization for RA-OCC was associated with significant improvement in renal function (P <.01); however, nephrectomy alone did not increase renal function significantly. Improved renal function after operation was associated with a significant and independent increase in survival (P <.01) and dialysis-free survival (P <.01) among patients treated for RA-OCC. In addition, blood pressure benefit, renal function response, and estimated survival did not differ significantly after reconstruction for RA-OCC or RAS. CONCLUSION: Among hypertensive patients treated for RA-OCC, equivalent beneficial blood pressure response was observed after both revascularization and nephrectomy. In patients who underwent bilateral renal artery revascularization, the change in excretory renal function attributable to repair of RA-OCC cannot be defined. In patients treated for unilateral disease, however, improvement in function was observed only after revascularization. Moreover, improved renal function demonstrated a significant and independent association with improved survival. This experience supports renal revascularization in preference to nephrectomy for RA-OCC in select hypertensive patients when a normal distal artery is demonstrated at operation.     

Tissue-specific regulation of IRS-1 in unilaterally nephrectomized rats

Insulin stimulates the tyrosine kinase activity of its receptor, resulting in the phosphorylation of its cytosolic substrate, insulin receptor substrate 1 (IRS-1). IRS-1 is also a substrate for different peptides and growth factors, and a transgenic mouse "knockout" for this protein does not have normal growth. However, the role of IRS-1 in kidney hypertrophy and/or hyperplasia was not investigated. In the present study we investigated IRS-1 protein and tyrosine phosphorylation levels in the remnant kidney after unilateral nephrectomy (UNX) in 6-week-old male Wistar rats. After insulin stimulation the levels of insulin receptor and IRS-1 tyrosine phosphorylation were reduced to 79 +/- 5% (P < 0.005) and 58 +/- 6% (P < 0.0001), respectively, of the control (C) levels, in the remnant kidney. It is possible that a circulating factor and/or a local (paracrine) factor playing a role in kidney growth can influence the early steps of insulin action in parallel. To investigate the hypothesis of a circulating factor, we studied the early steps of insulin action in liver and muscle of unilateral nephrectomized rats. There was no change in pp185 tyrosine phosphorylation levels in liver (C 100 +/- 12% vs UNX 89 +/- 9%, NS) and muscle (C 100 +/- 22% vs UNX 91 +/- 17%, NS), and also there was no change in IRS-1 phosphorylation levels in both tissues. These data demonstrate that after unilateral nephrectomy there is a decrease in insulin-induced insulin receptor and IRS-1 tyrosine phosphorylation levels in kidney but not in liver and muscle. It will be of interest to investigate which factors, probably paracrine ones, regulate these early steps of insulin action in the contralateral kidney of unilaterally nephrectomized rats.     

A novel 22q11.2 microdeletion in DiGeorge syndrome

BACKGROUND: Decreased red blood cell survival contributes to the anemia of chronic renal failure patients. Because patients on chronic dialysis therapy are frequently exposed to excessive complement activation, we investigated the susceptibility of this patient population to erythrocyte C5b-9 deposition, complement-mediated lysis, and ghost formation. METHODS: We developed a flow cytometric assay using antibodies to both glycophorin and the C5b-9 complex to detect C5b-9 deposition on intact erythrocytes and erythrocyte ghosts. Serum C5b-9 levels and C5b-9 deposition on erythrocyte ghosts were measured by enzyme-linked immunosorbent assay. RESULTS: A significant increase in C5b-9 deposition on intact erythrocytes was demonstrated in patients with advanced chronic renal failure (2.2 +/- 0.5%) and in patients on chronic maintenance hemodialysis (2.3 +/- 0.4%) compared with normal volunteers (0.9 +/- 0.1%, P = 0.005 vs. chronic renal failure, P < 0.001 vs. chronic hemodialysis patients). There was also a significantly higher percentage of C5b-9-positive erythrocyte ghosts in patients with advanced chronic renal failure (20.6 +/- 5%) and in chronic hemodialysis patients (15.5 +/- 3.1%) compared with normal controls (2.6 +/- 0.9%, P < or = 0.001 vs. advanced chronic renal failure and chronic hemodialysis patients). Treatment of erythrocyte preparations with cobra venom factor, which activates the complement cascade, resulted in dramatic increases in the percentages of C5b-9-positive erythrocyte ghosts in patients with chronic renal failure (49.9 +/- 6.9%) and in chronic hemodialysis patients (45.0 +/- 4.2%) compared with normal volunteers (22.3 +/- 2.7%, P < 0.001 vs. chronic renal failure and chronic hemodialysis patients). Erythrocyte membrane expression of the complement regulatory proteins CD59 and CD55 did not significantly differ between normal controls and hemodialysis patients. Plasma C5b-9 levels after cobra venom factor stimulation were higher in chronic renal failure patients (538 micrograms/ml) compared with normal controls (345 micrograms/ml, P < 0.001). CONCLUSIONS: Patients with chronic renal failure and on hemodialysis therapy are susceptible to erythrocyte C5b-9 deposition with subsequent lysis and ghost formation. Susceptibility to complement-mediated erythrocyte injury may contribute to the anemia of chronic renal disease.     

Reduced expression of the renal calcium-sensing receptor in rats with experimental chronic renal insufficiency

Chronic renal insufficiency is associated with elevated serum parathyroid hormone (PTH) levels (2 degrees HPT), deficiency of 1,25-dihydroxyvitamin D (1,25(OH)2D), and hypocalciuria. In chronic renal insufficiency, the 2 degrees HPT may result from reduced expression of the parathyroid gland extracellular Ca(2+)-sensing receptor (CaSR). Since the CaSR was cloned from rat and human kidney, this study examined in rats whether expression of the renal CaSR is altered in experimental chronic renal insufficiency. Four weeks after chronic renal insufficiency was induced by 5/6 nephrectomy (Nx) in Sprague Dawley rats, the serum creatinine concentration was 0.96+/-0.06 mg/dl compared with 0.35+/-0.02 mg/dl in sham-operated animals (P < 0.05). The serum total Ca2+ and phosphorus concentrations were not different. In the Nx group, the serum concentration of amino-PTH was higher (65+/-8 pg/ml), and the concentration of 1,25(OH)2D was significantly lower (47+/-5 pg/ml) compared with 45+/-5 pg/ml and 61+/-4 pg/ml (P = 0.05) in the sham group, respectively. In a subset of rats studied, the Nx group was hypocalciuric (1.4+/-0.5 mg/kg per d) compared with the sham group (3.7+/-0.5 mg/kg per d) (P < 0.05). In the Nx rats, CaSR mRNA expression and CaSR protein levels were found to be reduced by 35 and 38%, respectively, than those observed in controls. These results suggest that reduced renal CaSR expression in chronic renal insufficiency may play a role in disordered mineral ion homeostasis, including hypocalciuria.     

Plasma mevalonate concentrations in uremic patients

Mevalonic acid (mevalonate or MVA), is an obligate precursor in the biosynthetic pathway of cholesterol. It is partially metabolized by the kidneys and its plasma concentrations are an index of endogenous cholesterol synthesis. The aim of the present study was to evaluate plasma MVA concentrations in uremic patients with different degrees of chronic renal failure (CRF; group A), and the effects of a single hemodialysis treatment on plasma MVA in a group of patients with end-stage renal disease (ESRD; group B). CRF patients exhibited a higher mean basal mevalonate concentration (13.3 +/- 6.5 ng/ml) than control subjects (4.68 +/- 1.32 ng/ml; P < 0.001). A statistically significant direct correlation was evident in CRF patients between mevalonate and creatinine plasma levels (r = 0.86; P < 0.001). A single hemodialysis treatment was associated with a significant reduction of plasma mevalonate concentrations four hours after the hemodialysis session (-57%; P < 0.001) and an increase up to the basal values 24 hours after the end of the treatment. In conclusion, our results demonstrated: (i) higher plasma MVA concentrations in patients with decreased renal function; (ii) a direct relationship between plasma MVA levels and the degree of kidney failure as expressed by creatinine plasma concentrations; and (iii) a clear cut reduction of elevated plasma MVA levels after a single hemodialysis treatment.     

Differential response of glomerular epithelial and mesangial cells after subtotal nephrectomy

Recent studies in both human and experimental chronic renal disease suggest that there is a linkage between glomerular hypertrophy and glomerulosclerosis. To further define these relationships, we studied the changes in glomerular hypertrophy, procollagen alpha 1(IV) mRNA levels and glomerulosclerosis in rats undergoing 1 2/3 nephrectomy (Nx) or sham nephrectomy (SNx). Glomerular hypertrophy, measured biochemically by RNA/DNA and protein/DNA ratios, was significantly increased in Nx compared to SNx two days after subtotal renal ablation (RNA/DNA: Nx = 133 +/- 8%, SNx = 100 +/- 3% of the mean control value, P < 0.01; protein/DNA: Nx = 164 +/- 22%, SNx = 100 +/- 10%, P < 0.05) and remained elevated after 7 and 15 days (RNA/DNA: seven days Nx = 155 +/- 3%, SNx = 100 +/- 13%, P < 0.01; 15 days Nx = 303 +/- 21%, SNx = 100 +/- 24%, P < 0.001; protein/DNA: seven days Nx = 228 +/- 57%, SNx = 100 +/- 18%, P < 0.05; 15 days Nx = 341 +/- 23%, SNx = 100 +/- 18%, P < 0.01). Light microscopic measures of glomerular tuft volume (GTV) were too insensitive to detect glomerular enlargement until 15 days postoperatively, but GTV measured ultrastructurally demonstrated a 20% increment in Nx compared to SNx as early as two days postoperatively (P < 0.01). The latter increment in GTV was due exclusively to glomerular visceral epithelial cell (GVEC) expansion. Glomerular procollagen alpha 1(IV) mRNA levels were significantly elevated only 15 days after nephrectomy (Nx = 265 +/- 58% of the mean control value, SNx = 100 +/- 12%, P < 0.05; corrected for beta-actin mRNA levels). As this time, exuberant mesangial expansion measured ultrastructurally contributed to a 1.6 +/- 0.1-fold increase in GTV (P < 10(-5)), and to a relative decrement in the GVEC contribution to glomerular cells plus matrix (P < 0.01). Segmental sclerosis was observed only 15 days postoperatively in Nx (Nx = 1.3 +/- 0.4% of glomeruli evaluated, SNx = 0.0%, P < 0.05), and there was a strong correlation between the prevalence of segmental sclerosis and the procollagen alpha 1(IV) mRNA levels in Nx at 15 days (r = 0.93, P < 0.01). There was no significant correlation between the RNA/DNA and protein/DNA ratios and procollagen alpha 1(IV) mRNA levels. Thus, glomerular regions responded differentially to subtotal nephrectomy. Early epithelial cell expansion was followed by later mesangial expansion. Glomerular procollagen alpha 1(IV) mRNA levels were elevated only during the second (mesangial) phase of glomerular hypertrophy, when it correlated with glomerulosclerosis, but not during the initial (epithelial) phase, a pattern consistent with a mesangial origin of the procollagen alpha 1(IV) mRNA.     

Regional differences in age-related decrements of the cutaneous vascular and sweating responses to passive heating

This study was performed to evaluate prognostic factors in ADPKD progression to ERSF. Previously reported negative factors (male gender, age, hypertension, palpable kidneys and UTI) as well as the extra-renal presence of cysts and proteinuria, were analysed in a group of 45 ADPKD patients (Male/Female, 25/20; Age = 40.1 +/- 19.7 yrs, range 21-69). Palpable kidneys were associated with higher serum creatinine values (955 +/- 689 vs 743 +/- 504 umol/l, p < 0.001) but not with a greater prevalence of renal failure. Renal failure (100% vs 60%), higher creatinine values (981 +/- 495 vs 778 +/- 654 umol/l) and hypertension (50% vs 18%) were related to a higher prevalence of extra-renal cysts (p < 0.05). Older patients (> 40 years) had a greater prevalence of renal failure (96% vs 32%, p < 0.001). Also, subjects with palpable kidneys, and those with extra-renal cysts, were significantly older (52.8 +/- 10.3 vs 30.5 +/- 20.6 yrs, p < 0.025; and 42.1 +/- 21.9 vs 38.1 +/- 18.2 yrs, p < 0.025). Patients with renal failure and those with extra-renal cysts had a greater prevalence of proteinuria (65% vs 0%, p < 0.001; and 100% vs 24%, p < 0.001). No correlation was seen for male gender, hypertension or UTI with any known complications of ADPKD. The extrarenal presence of cysts, older age, proteinuria and palpable kidneys were associated with a worse renal outcome, but for this Romanian population we can't confirm previous reports suggesting a role for male gender and early onset of disease.     

Improved kidney function with intravenous prostaglandin E1 in patients with terminal heart failure

In end stage congestive heart failure activation of a series of compensatory mechanisms increase renal vascular resistance and impair renal function. Prostaglandin E1 is increasingly used in the treatment of severe heart failure for its vasodilating actions. In various experimental settings prostaglandin E analogues are known to improve renal function by modulating renal filtration pressure and redistribution of renal blood flow. However, prostaglandin E1 decreases systemic blood pressure and thus, also renal perfusion pressure, a fact by which renal function might be further compromized in heart failure patients. The aim of the study was to evaluate the effects of prostaglandin E1 on excretory renal function in patients with end stage heart failure and to prove the hypothesis, that the well known local actions of prostaglandins on renal microcirculation might outweigh the negative impact of an expected decrease in perfusion pressure. 25 patients with terminal congestive heart failure were investigated. 13 patients received prostaglandin E1 at a dose of 13.5 +/- 1.9 ng/kg/min in combination with constant rates of dopamine and dobutamine (group A), 12 patients received prostaglandin E1 at a dose of 10.3 +/- 1.7 ng/kg/min without catecholamines (group B). There was no significant difference in prostaglandin dosages between groups. Kidney function was assessed by measuring plasma creatinine and urea nitrogen, urinary output, creatinine clearance, osmotic and free water clearance at baseline and after 72 h of infusion therapy. Hemodynamic parameters were measured by using a balloon tipped pulmonary arterial catheter. Hemodynamic measurements during infusion showed a significant improvement in all patients. At the same time as expected mean arterial pressure decreased in both groups (p < 0.001). Nevertheless, in both groups a significant increase of creatinine clearance during infusion was observed (in group A from 45 ml/min to 78 ml/min., p < 0.05, in group B from 59 ml/min to 105 ml/min., p < 0.001). Creatinine clearance in group B (without catecholamines) reached higher levels than group A (p < 0.05). Urinary volumes did not change during infusion therapy, whereas free water clearance significantly decreased, as an indication of an improvement of renal concentrations ability. We conclude, that in patients with end stage heart failure continuous infusion of prostaglandin E1 improves excretory kidney function. These findings suggest that the local effects of prostaglandin E1 on renal microcirculation can counterregulate the negative impact of prostaglandins on renal perfusion pressure.     

Renal reserve is normal in adults born with unilateral renal agenesis and is not related to hyperfiltration or renal failure

This study was carried out to examine the renal hemodynamic response in adult patients with single kidneys born with unilateral renal agenesis. A group of 21 patients with unilateral renal agenesis were divided into three groups according to their glomerular filtration rate (GFR): 112 +/- 3 ml/min x 1.73 m2 in group A, 68 +/- 3.2 ml/min x 1.73 m2 in group B, and 40.7 +/- 3.3 ml/min x 1.73 m2 in group C. Mean arterial blood pressure was significantly higher in the patients of group C who were also proteinuric. The renal hemodynamic response to an oral protein load (2 g/kg of protein as beefsteak) was normal in all groups and unrelated to hyperfiltration or to renal failure and proteinuria. The study indicates that in patients with renal agenesis, the hemodynamic response to a protein challenge is similar to that of kidney donors, renal transplant recipients and uninephrectomized patients. The paper also demonstrates that the renal response to a protein challenge is inadequate to identify patients with renal agenesis who are at risk of developing renal disease. Finally, in renal agenesis with renal disease, creatinine clearance overestimated the GFR by an average of 32.7%.     

Contribution of tubular injury to loss of remnant kidney function

BACKGROUND: The remnant kidney model has been widely used to identify mechanisms responsible for the progression of renal disease. However, the structural changes associated with progressive loss of function in this model have not been well characterized. METHODS: Kidney function and structure were assessed at 10 weeks (REM 10) and 25 weeks (REM 25) after five-sixths renal ablation and in control rats (Control). Serial sections were examined to relate glomerular and tubular structure in individual nephrons. RESULTS: Remnant kidney function declined between 10 and 25 weeks after ablation (GFR 0.90 +/- 0.34 vs. 0.23 +/- 0.07 ml/min, REM 10 vs. REM 25, P < 0.05). This decline in function was associated with an increase in the prevalence of globally sclerotic glomeruli (14 +/- 10 vs. 0 +/- 0 vs. 0 +/- 0%, REM 25 vs. REM 10 vs. Control, P < 0.05 REM 25 vs. REM 10 and Control). The decline in remnant kidney function between 10 and 25 weeks was also associated with the appearance of glomeruli that were atubular (48 +/- 14 vs. 9 +/- 8 vs. 3 +/- 5%, REM 25 vs. REM 10 vs. Control, P < 0.05 REM 25 vs. REM 10 and Control) or connected to atrophic proximal tubule segments (26 +/- 10 vs. 11 +/- 6 vs. 1 +/- 2%, REM 25 vs. REM 10 vs. Control, P < 0.05 all comparisons). Atubular glomeruli, which usually had open capillary loops available for filtration, were more numerous than globally sclerotic glomeruli at 25 weeks after ablation. CONCLUSIONS: These findings indicate that tubular injury contributes to progressive loss of renal function following reduction in nephron number.     

Can fingernail creatinine concentrations be used to predict duration of azotemia?

Clinical use of fingernail creatinine estimation to predict duration of azotemia is yet to be validated. We studied the fingernail creatinine concentrations in 48 subjects: seven controls, nine with acute renal failure, five with rapidly progressive glomerulonephritis, 12 with chronic renal failure and 15 with end-stage renal failure on maintenance hemodialysis. The creatinine concentration in aqueous eluates of powdered nail clippings was determined by the alkaline picrate reaction. The mean fingernail creatinine concentration was significantly higher in patients with chronic renal failure (93.7 +/- 83.7 micrograms/g) and end-stage renal disease on maintenance hemodialysis (118.4 +/- 46.8 micrograms/g) as compared to those with acute renal failure (36.6 +/- 23.7 micrograms/g) and rapidly progressive glomerulonephritis (35.8 +/- 20.6 micrograms/g). The creatinine concentrations did not differ significantly between normal subjects (27.2 +/- 28.7 micrograms/g) and those with acute renal failure and rapidly progressive glomerulonephritis. However because of large variability in the values of fingernail creatinine concentrations within each group, the test lacked specificity. Therefore, this investigation is an unreliable indicator of duration of azotemia in individual patients and is not likely to be of much clinical use.     

Lipoproteins and lipid peroxidation abnormalities in patients with chronic renal disease

Increasing experimental and clinical evidence suggests that lipoproteins and lipid peroxidation can be important modulators in progressive kidney disease. A group of 54 patients with varying degrees of kidney impairment was studied to find the abnormalities in lipoproteins and lipid peroxidation. Lipoproteins and lipid peroxidation products, malondialdehyde (MDA) were measured in the plasma of 54 chronic renal disease patients CGN 33, nephrosclerosis 11, 7CTIN, 1PCKD, unknown 2 and compared with values obtained from 32 healthy controls. The patients were divided into 5 groups according to serum creatinine levels: Group 1 (serum creatinine of 2 mg/dl), group 2 (S. creatinine > 2-4 mg/dl), group 3 (S. creatinine > 4-8 mg/ dl), group 4 (S. creatinine > 8-12 mg/dl), group 5 (S. creatinine > 12 mg/dl). Plasma cholesterol was higher significantly than controls in patients with group 1, 2 and 3 (p < 0.01, < 0.001, < 0.05) respectively while plasma LDL-chol was statistically significantly different from controls only in group 2 patients (p < 0.001). Plasma VLDL-chol, beta-VLDL-chol, triglycerides, ratio of chol/HDL and LDL/ HDL showed high levels in all groups compared with controls but more evident in patients of group 2. Plasma HDL-chol decreased during the progression of renal failure. All groups had significantly elevated plasma malonyldialdehyde (MDA) vs controls (p < 0.001), especially highest value was found in group 2. Triglycerides, beta-VLDL chol, VLDL-chol LDL/HDL, chol/HDL correlated very closely with plasma MDA levels and also with serum creatinine. Patients with chronic renal disease showed lipoprotein abnormalities and accelerated lipid peroxidation. The evidence was more marked in patients with normal to mild renal insufficiency which suggested the role of oxidative stress early in the course of nephron injury.     

Hemodynamic characterization of YM435, a novel dopamine DA1 receptor agonist, in anesthetized dogs

In previous studies on experimental renal failure, hypertrophy of cardiomyocytes, diminished capillarization, and increased intercapillary distances had been observed, abnormalities that will expose the heart to reduced ischemia tolerance. It has not been established, however, whether such structural alterations are unique for the heart (eg, as a consequence of left ventricular hypertrophy) or are demonstrable in other tissues as well. Clarification of this point is important to test hypotheses on some potential mechanisms for cardiac undercapillarization. To address this issue further, we compared capillary length density (by stereologic techniques) in perfusion-fixed skeletal muscle (m. psoas) and hearts of subtotally nephrectomized (SNX) rats with moderate renal failure to those in sham-operated pair-fed controls. The duration of renal failure was 8 weeks. SNX rats had significantly higher mean systolic blood pressure (128 mm Hg v 109 mm Hg), serum creatinine, and urea levels. Despite pair feeding, the mean body weight was significantly lower in the SNX rats (409 g v 471 g), but the left ventricular weight to body weight ratio tended to be higher than in the sham-operated controls (2.39 mg/g v 2.13 mg/g). In the heart, myocyte mean cross-sectional area (675 +/- 112 microm2 v 545 +/- 111 microm2) and volume density of nonvascular interstitial tissue (3.47 +/- 1.04 v 1.33 +/- 0.22) were significantly higher in the SNX rats than in the controls. In parallel, myocardial capillary length density was significantly reduced after subtotal nephrectomy (3,036 +/- 535 mm/mm3 v 3,916 +/- 615 mm/mm3). In contrast, in skeletal muscle, myocyte cross-sectional area (3,109 +/- 783 microm2 v 3,042 +/- 639 microm2), capillary length density (718 +/- 248 mm/mm3 v 717 +/- 184 mm/mm3), and three-dimensional capillary fiber ratio (2.10 +/- 0.26 v 2.13 +/- 0.4) were similar in SNX and control rats. These data document a selective defect of capillarization in the heart of animals with moderate renal failure, pointing to tissue-specific abnormalities of cardiac capillarogenesis.     

Renography before heart transplantation in patients with cardiomyopathy

In patients with ischemic cardiomyopathy (CM), abnormal renograms may result not only from circulatory failure (which should reverse after transplantation) but also from intrinsic renal disease (which contraindicates heart transplantation). Here, the outcome of heart transplantation was related to preoperative renograms, and the differentiating and prognostic value of renography was analyzed. METHODS: The study population consisted of 50 patients with ischemic CM expecting heart transplantation. Anatomical renal pathology was excluded in all patients. Dynamic renal scintigraphy was performed with 99mTc-mercaptoacetyltriglycine. Background-subtracted renograms were inspected visually and characterized numerically. Mean parenchymal transit time (mPTT), renal tracer content at 15 min (RTC15) and retention index (RI) were determined. The parametric renogram values were related to a normal reference group of 64 patients. The preoperative renograms were matched with the postoperative outcome. RESULTS: Three characteristic types of symmetrical findings in the kidneys were found: no pathological findings, mildly delayed peak and excretion phase and severely delayed peak and excretion phase. Pathological renograms were observed in 36 of 50 (72%) patients. The mean parametric renogram values in ischemic CM were as follows: Group A (normal kidney function), mPTT = 142+/-26.6 sec, RTC15 = 22.3%+/-4.6% and RI = 24.7+/-11.9; Group B (mild dysfunction), mPTT = 210+/-44.0 sec, RTC15 = 42.6%+/-10.3% and RI = 101.4+/-50.5; Group C (severe dysfunction), mPTT = 320+/-94.2 sec, RTC15 = 79.6%+/-15.9% and RI = 347.7+/-194.7; and reference patients (normal kidney function), mPTT = 137+/-31.1 sec, RTC15 = 22.8%+/-3.8% and RI = 24.6+/-7.9. Postoperative serum creatinine levels were <1.5 mg/dl in all Group A patients, between 1.5 and 2.5 mg/dl in 78% of Group B patients and >2.5 mg/dl in 75% of Group C patients. CONCLUSION: Renography revealed abnormal kidney function when structural pathology was excluded. The renographic abnormalities in ischemic CM did not reflect simply the circulatory failure. The numerical grading of renograms allowed patient stratification, suggestive of possible renal insufficiency after cardiac transplantation and immunosuppressive therapy. With further experience, renography may become a useful tool for predicting postoperative outcome in ischemic CM.     

The role of oxygen free radicals in acute renal failure complicating obstructive jaundice: an experimental study

Oxidant injury is considered to be an important mechanism in the pathophysiology of acute renal failure. It has been thought that decrease in extracellular and intracellular fluid and endotoxemia seen in obstructive jaundice may cause an increase in production of oxygen free radicals and impairment in antioxidant defense mechanism. This study is designed to investigate the possible role of oxidant injury in renal failure seen in jaundiced patients. In this study, 28 rats were divided into four groups: Control (C)(N = 7); Renal ischemia (RI)(N = 7); Obstructive jaundice+renal ischemia (OJ+RI)(N = 7); Obstructive jaundice (OJ)(N = 7). All groups were compared with each other according to renal failure findings and enzyme activities, such as Xanthine oxidase (XOD), Superoxide Dismutase (SOD) and Catalase in renal cortex and Glutathione Peroxidase (GSH-Px), in blood at 3rd day after ischemia and reperfusion. Renal failure findings monitored by blood urea and creatinine levels, seemed more evident in OJ+RI than RI group (p < 0.05). When compared with RI, in OJ+RI group, increase in XOD activity at 3rd day was statistically significant [0.259 +/- 0.01 U/g (tissue) and 0.362 +/- 0.03 U/g (tissue) respectively] (p < 0.05). SOD and GSH-Px activities of each ischemic group at 3rd day were decreased compared to non-ischemic groups. This fall was significant (p < 0.05). But there was no statistical difference between jaundiced and non-jaundiced groups. Alterations in catalase activities also had no statistical significance. These findings may suggest that the injury induced by oxygen free radicals at re-oxygenation of tissue after ischemia may also play a role in the pathogenesis of acute renal failure developed in obstructive jaundice.