24-hour Urinary Protein Excretion Research Articles

Quantitation of proteinuria by spot urine sampling

Few studies have shown that calculation of protein/creatinine ratio in a spot urine sample correlates well with the 24-hour urine collection. A study was conducted to compare the accuracy of a spot urinary protein/creatinine ratio (P/C ratio) and urinary dipstick (albustix) with the 24-hour urine protein (24-HUP). Fifty samples from 26 patients were collected. This included a 24-hour urine sample followed by the next voided spot sample. The protein/creatinine ratio was calculated and dipstick (albustix) was performed on the spot sample. This was compared with the 24-hour urine protein excretion. The correlation between the three samples was statistically highly significant (p=<0.001) for all levels of proteinuria. The normal value of protein/creatinine ratio in Indian children was also estimated on 100 normal children attending the OPD and was calculated to be 0.053 (S.E of mean±0.003).

Urinary excretion of interleukin-6 correlates with proteinuria in acute Puumala hantavirus-induced nephritis

Background: Nephropathia epidemica (NE) is a mild type of hemorrhagic fever with renal syndrome caused by Puumala Hantavirus. Cytokines are thought to have an important role in the pathogenesis of NE. The aim of this study is to evaluate whether cytokines contribute to renal involvement in NE. Methods: Overnight urinary excretion of interleukin-1β (IL-1β), IL-1 receptor antagonist (IL-1Ra), IL-6, tumor necrosis factor-α (TNF-α), albumin, immunoglobulin G (IgG), and α1-microglobulin and quantitative 24-hour urinary protein excretion were measured for 3 consecutive days from 70 hospitalized patients with acute NE (49 men, 21 women; age, 15 to 70 years; median age, 39 years). Plasma levels of the respective cytokines also were measured. Urinary collections were repeated after 1 year. The control group for blood samples included 400 healthy blood donors. Results: Maximum median urinary IL-6 excretion in the acute phase of NE was increased compared with values detected after 1 year (49.5 versus 0.7 pg/min; P < 0.001). Correspondingly, maximum median plasma IL-6 concentration in patients was increased compared with controls (14.6 versus 1.2 pg/mL; P < 0.001). Urinary IL-6 excretion correlated with urinary albumin, IgG, and protein excretion (r = 0.79; P < 0.001; r = 0.76; P < 0.001; and r = 0.65; P < 0.001, respectively), but not plasma IL-6 levels (r = 0.18; P = 0.148). Conclusion: Plasma IL-6 concentrations and urinary IL-6 excretion were markedly increased in patients with acute NE, but there was no correlation between plasma and urinary IL-6 levels. The high urinary IL-6 levels might reflect local production of this proinflammatory cytokine in the kidneys during acute infection.

Correlation between 24-hour urinary protein excretion and protein/creatinine ratio in the first voided morning urine samples

To collect 24-hour urine of infants and young children is so difficult that 24-hour urinary protein excretion (24 H-UP) has been estimated from single voided urine samples. We investigated the correlation between 24 H-UP and the protein/creatinine ratio of the first voided morning urine samples (MUP/Cr) and evaluated the problems associated with this method. Six hundred and thirty-nine specimens, pairs of morning spot urine and 24-hour collected urine, were collected from 158 patients, aged 3 to 28, who were being followed at Kyoto City Hospital. The study population was divided into different subgroups by age, disease category and inpatient or outpatient status and linear regression analysis was performed for every subgroup. Although MUP/Cr correlated well with 24 H-UP, it was necessary to revise the estimation of 24 H-UP from MUP/Cr, which is lower in infants and young children because of age-related differences in creatinine excretion. If the patient's age is younger, the creatinine excretion rate is lower. The difference in 24 H-UP estimated from MUP/Cr was significant between inpatients and outpatients, with the estimated value being higher in outpatients than inpatients. The estimated value was also different according to disease category. We speculated that the difference in estimated 24 H-UP was affected by different rate of creatinine excretion related to age and other factors.

The effects of dual blockade of the renin- angiotensin system on urinary protein and transforming growth factor-b excretion in 2 groups of patients with IgA and diabetic nephropathy

The therapeutic benefits of dual blockade of the renin-angiotensin system (RAS) have been inconsistent on renal function and proteinuria. To know the contribution of the heterogeneity of study subjects to such inconsistency, we evaluated the effects of dual blockade of RAS in 2 groups of selected renal diseases, IgA and diabetic nephropathy. To avoid confounding by the blood pressure-reducing effects, angiotensin II receptor antagonists (ATRAs) were added on the patients with long-term, optimally controlled blood pressure taking ACE inhibitors. Twenty-four-hour urinary protein excretion rate and urinary TGF-beta1 level were measured as surrogate markers of renal injury. We conducted a prospective crossover trial with 14 IgA and 18 type-2-diabetic nephropathy patients showing moderate degree of proteinuria (> or = 1.0 g/day) and renal dysfunction (creatinine clearance 25 - 75/ml/min). Four to 8 mg once-daily dose of candesartan and placebo were alternatively added on ramipril dose of 5 - 7.5 mg/day for 16 weeks. All baseline data except for the age factor were statistically the same between the 2 disease groups. Twenty-four-hour mean arterial blood pressures were 91.2 +/- 1.6 and 92.3 +/- 1.8 mmHg in IgA and diabetic nephropathy patients respectively at baseline (p = NS). Mean arterial pressure did not change by the addition of candesartan or placebo in both groups. The addition of candesartan (combination) reduced 24-hour urinary protein excretion rate in IgA nephropathy patients with a mean change of -12.3 +/- 4.5%, which is significantly greater compared to a mean change of -0.1 +/- 3.3% after the addition of placebo (placebo) (mean difference 12.4 +/- 5.0, 95% CI 1.2 - 23.5; p < 0.05). Urinary TGF-beta1 level was reduced considerably by the combination therapy, with a -28.9 +/- 6.0% decrease, which was significantly different to that by the placebo, with +4.3 +/- 12.4% (33.3 +/- 13.5, 3.2 - 63.3; p < 0.05). In diabetic nephropathy patients, the addition of candesartan did not reduce 24-hour urinary protein excretion rate. Mean changes of 24-hour urinary protein excretion rate were -0.8 +/- 4.7% by the combination therapy and +0.5 +/- 6.1% by placebo (mean difference 1.3 +/- 4.7, 95% CI -6.8 - 13.5; p < NS). The level of urinary TGF-beta1 was reduced by the combination therapy, with -14.3 +/- 9.5% decrease, but it did not reach statistical significance compared to placebo of +0.7 +/- 15.5% (15.0 +/- 13.5, -14.4 - 44.5; p < NS). The changes in 24-hour urinary protein excretion rate and urinary TGF-beta1 level were neither correlated with each other, nor with the change in mean arterial pressure. Significant changes in the renal function were not detected during the study period. Definite beneficial effects of dual blockade of RAS on proteinuria and TGF-beta1 excretion were found in IgA nephropathy patients, which was independent of blood pressure-reducing effect. With our 16-week trial, such benefits were not observed in type 2 diabetic nephropathy. The reduction in urinary TGF-beta1 level suggests that the combination therapy may provide additional renoprotection through the antisclerosing effects. Based on our results, for a proper interpretation the therapeutic effects of the combination therapy should be evaluated separately according to the underlying renal disease.

Chronic Nephropathies: Individual Risk for Progression to End-Stage Renal Failure as Predicted by an Integrated Probabilistic Model

Background/Aims: To predict risk of end-stage renal disease (ESRD) in individual patients with chronic nephropathy. Methods: Sequential use of univariate analyses and Cox regression to identify risk factors, artificial neural network to quantify their relative importance and Bayesian analysis to address uncertainty of relationships and incorporate ESRD prevalence information in 344 patients with chronic nephropathy enrolled in the Ramipril Efficacy In Nephropathy study. Results: Serum creatinine (SC), 24-hour urinary protein excretion (UPE) and calcium-phosphorus (Ca*P) product were, in this order, the strongest time-adjusted ESRD predictors. Individual risk of ESRD ranged from near zero when SC and UPE were <1.66 mg/dl and <3 g/24 h, to 69% when SC, UPE and Ca*P were ≧2.41 mg/dl, ≧3 g/24 h and ≧32.64 mg²/dl², respectively. Receiver operating characteristic curves showed that within lowest, middle and highest tertiles of basal SC (0.90–1.65, 1.66–2.40 and 2.41–6.30 mg/dl, respectively) the model accurately predicted ESRD (AUC = 0.80, 0.72 and 0.65; p = 0.0003, 0.0001 and 0.0022, respectively), quality of life or treatment costs. Conclusion: Integrated use of regression analysis and probabilistic models allows computation of individual risk of progression to ESRD and related utilities. This may help in optimizing care and costs in nephrology and other medical areas and designing trials in high-risk patients.

Validity of protein-osmolality versus protein-creatinine ratios in the estimation of quantitative proteinuria from random samples of urine in children

Background:Proteinuria is an important marker of kidney disease. Simple methods to determine the presence of proteinuria in a semiquantitative fashion require measurement of either a protein-creatinine or protein-osmolality ratio. Methods:Urine samples from 134 healthy infants and children and 150 children from the pediatric nephrology practice were analyzed to develop normative data for protein-osmolality ratios on random urine samples and compare protein-osmolality with protein-creatinine ratio as a predictor of 24-hour urine protein excretion. Children were grouped according to age. Three groups were established: infants (<2 years), younger children (2 to 8 years), and older children (9 to 18 years). An adult cohort was similarly analyzed. Results:For healthy children older than 2 years, the optimal value discriminating normal from abnormal protein excretion was determined to be a protein-osmolality ratio of 0.15 mg · kg H2O/mOsm · L; for children between 2 and 8 years old, 0.14; and for children older than 8 years, 0.17 (P = not significant between age groups). The corresponding optimal cutoff value for protein-creatinine ratio for the entire group of children older than 2 years is 0.20. Area under the curve analysis of receiver operator characteristic curves showed protein-creatinine ratio was superior to protein-osmolality ratio for predicting abnormal amounts of proteinuria in children and adolescents (P < 0.0001). In adults, both ratios are equally accurate. Conclusion:Given the superiority of protein-creatinine ratio in children, it would be appropriate to screen urine samples for proteinuria using protein-creatinine ratio rather than protein-osmolality ratio.

Quantitation of 24-hour urine protein excretion in kidney transplant patients by the use of protein to creatinine ratio

Quantitation of 24-hour urine protein excretion in kidney transplant patients by the use of protein to creatinine ratio

Prediction of 24-hour protein excretion in pregnancy with a single voided urine protein-to-creatinine ratio

Objective: This study was undertaken to validate the prediction of 24- hour urine protein excretion by a single voided urine protein-to-creatinine (P:C) ratio in a hospitalized pregnant population at our institution. We sought to evaluate the ability of serial single voided P:C ratios to follow the course of proteinuria. Study Design: Pregnant patients who were admitted to the antepartum unit at Northwestern Memorial Hospital and who were undergoing a 24-hour urine collection for the quantitation of proteinuria were recruited. A single voided urine specimen was obtained after the completion of the 24-hour urine collection and analyzed for the P:C ratio. Results: Thirty patients completed the study. There was a significant correlation between the 24-hour urine protein and the P:C ratio (r = 0.93, P <.001). The associations of maternal age and gestational age at collection with P:C ratio and 24-hour urine protein were weak and not significant. There was a nonsignificant trend of higher P:C ratios and 24-hour urine protein in nulliparous patients compared with multiparous patients. On the basis of multiple linear regression, there was no confounding effect of maternal age, gestational age, or parity. Eight patients had serial paired urine collections performed. In all of the cases, the trend of increasing or decreasing 24-hour urine protein excretion was predicted by the P:C ratio. Conclusion: Our data support the use of single voided P:C ratio in hospitalized pregnant patients to predict the 24-hour urine result. In addition, the P:C ratio appears to predict trends in protein excretion over time. (Am J Obstet Gynecol 2002;186:883-6.)

Impacto de los componentes y sistemas de medición de la presión arterial sobre la lesión de órgano diana y las complicaciones cardiovasculares en la hipertensión arterial

The goal of this study was to evaluate the relative association of several components of blood pressure (BP), as measured in the office and by ambulatory monitoring (ABPM), with clinically useful indicators of target organ damage and cardiovascular events (CE) in essential hypertensive patients. We retrospectively included 390 hypertensives (55% men; mean age: 56 years) between 1989 and 1998. All them had a baseline office BP measurement and a valid 24-hour ABPM record, both performed while the patient was free of antihypertensive therapy. Estimates of target organ damage included electrocardiographic indexes of left ventricular hypertrophy (Cornell and Sokolow-Lyon), serum creatinine, 24-hour urine protein excretion and creatinine clearance. Multiple linear regression and logistic regression analyses were used to evaluate the relationship between BP and target organ damage or CE. Forty-nine patients had CE (26 stroke, 18 myocardial infarction and 5 both). The BP parameter correlating better with cardiovascular events was office pulse pressure (multivariate odds ratio: 1.03; CI 95%: 1.00-1.05; p = 0.0095). Nevertheless, cardiac growth indexes correlated better with ABPM measurements. In fact, Cornell index correlated with night-time systolic BP (standardized regression coefficient beta: 0.260; p < 0.001) and Sokolow-Lyon index correlated with day-time systolic BP ( beta: 0.257; p < 0.001). Creatinine clearance inversely correlated with night-time pulse pressure ( beta: 0.122; p = 0.017) while proteinuria correlated better with 24-hour systolic BP ( beta: 0.390; p < 0.001). Whereas office BP (especially pulse pressure) is associated with the development of CE, ABPM estimates show a better association with target organ damage, especially systolic and pulse pressures.

RENAL OUTCOME 25 YEARS AFTER DONOR NEPHRECTOMY

The extended outcome after kidney donation has been a particular concern ever since the recognition of hyperfiltration injury. Few published reports have examined donor renal outcome after 20 years or greater. Kidney transplantation has been performed at the Cleveland Clinic Foundation since 1963, at which there is extensive experience with live donor transplantation. We assess the impact of donor nephrectomy on renal function, urinary protein excretion and development of hypertension postoperatively to examine whether renal deterioration occurs with followup after 20 years or greater. From 1963 to 1975, 180 live donor nephrectomies were performed at the Cleveland Clinic. We attempted to contact all patients to request participation in our study. Those 70 patients who agreed to participate in the study were mailed a package containing a 24-hour urine container (for assessment of creatinine, and total protein and albumin), a vial for blood collection (for assessment of serum creatinine) and a medical questionnaire. All specimens were returned to and processed by the Cleveland Clinic medical laboratories. Blood pressure was taken and recorded by a local physician. A 24-hour creatinine clearance and the Cockcroft-Gault formula were used to estimate renal function, and values were compared with an age adjusted glomerular filtration rate for a solitary kidney. Mean patient followup was 25 years. The 24-hour urinary creatinine clearance decreased to 72% of the value before donation. For the entire study cohort serum creatinine and systolic blood pressure after donation were significantly increased compared with values before, although still in the normal range. The overall incidence of hypertension was comparable to that expected in the age matched general population. There was no gender or age difference (younger or older than 50 years) for 24-hour urinary creatinine clearance, or change in serum creatinine before or after donation. Urinary protein and albumin excretion after donation was significantly higher in males compared with females. There were 13 (19%) subjects who had a 24-hour urinary protein excretion that was greater than 0.15 gm./24 hours, 5 (7%) of whom had greater than 0.8. No gender difference was noted in blood pressure, and there were no significant changes in diastolic pressure based on gender or age. Overall, renal function is well preserved with a mean followup of 25 years after donor nephrectomy. Males had significantly higher protein and albumin excretion than females but no other clinically significant differences in renal function, blood pressure or proteinuria were noted between them or at age of donation. Proteinuria increases with marginal significance but appears to be of no clinical consequence in most patients. Patients with mild or borderline proteinuria before donation may represent a subgroup at particular risk for the development of significant proteinuria 20 years or greater after donation. The overall incidence of proteinuria in our study is in the range of previously reported values after donor nephrectomy.

Renal function in relation to three candidate genes

We recently found that femoral intima media thickness, as well as the incidence of hypertension, is influenced by genes encoding the angiotensin-converting enzyme (ACE; insertion/deletion [I/D]) polymorphism, α-adducin (Gly460Trp), and aldosterone synthase (−344C/T). By interfering with blood pressure or sodium homeostasis, these genetic polymorphisms also may change renal function. We therefore investigated serum creatinine level, calculated and measured creatinine clearances, and 24-hour urinary protein excretion in subjects previously genotyped for these three polymorphisms. The 1,454 participants drawn at random from the population (64.3% of those invited) were aged 43.4 years and included 744 women (51.2%). Blood pressure, measured by study nurses at subjects' homes, averaged 123/76 mm Hg. Mean values were 90 μmol/L for serum creatinine; 84 and 88 mL/min/1.73 m2 for calculated and measured (n = 855) creatinine clearances, respectively; and 90 mg/d of protein for proteinuria (n = 556). The prevalence of mild renal dysfunction (creatinine clearance ≤ 60 mL/min/1.73 m2) was nearly 11%. In single-gene analyses with adjustment for significant covariables, the risk for mild renal dysfunction was positively associated with the ACE D allele. However, multiple-gene analyses showed that these associations were restricted to carriers of the mutated α-adducin Trp allele (40.1% of all subjects). Findings remained similar after hypertensive patients and women on hormonal therapy were excluded. In this phenotypically more homogeneous subgroup, serum creatinine level was 3.6 μmol/L (P = 0.02) and relative risks for mild renal dysfunction and proteinuria were 1.7-fold (P < 0.001) and 26% (P = 0.02) greater in ACE D subjects than ACE II homozygotes, respectively. The aldosterone synthase T allele did not strengthen genetic associations with the ACE D allele considered alone or in combination with the α-adducin Trp allele. Thus, in the present cross-sectional analysis, renal function was slightly but consistently impaired when both the ACE D and α-adducin Trp alleles were present. These findings, together with experimental studies and our previous reports on femoral intima media thickness and the incidence of hypertension, constitute a growing body of evidence delineating a clinical entity genetically determined by the risk-carrying ACE D and α-adducin Trp alleles. © 2001 by the National Kidney Foundation, Inc.

Effect of Dose-Intensive Intravenous Melphalan and Autologous Blood Stem-Cell Transplantation on AL Amyloidosis–Associated Renal Disease

Dose-intensive intravenous melphalan with autologous blood stem-cell transplantation induces remission of the plasma cell dyscrasia in a substantial proportion of patients with AL amyloidosis. The impact of this treatment on associated renal disease is not known. To determine the effect of dose-intensive intravenous melphalan and autologous blood stem-cell transplantation on AL amyloidosis-associated renal disease. Prospective cohort study. Academic medical center. 65 patients with AL amyloidosis and urinary protein excretion greater than 1 g/24 h who received dose-intensive intravenous melphalan and autologous blood stem-cell transplantation between 1 July 1994 and 30 June 1998. 24-hour urinary protein excretion, serum cholesterol level, serum albumin level, creatinine clearance, urine and serum immunoelectrophoresis, and bone marrow biopsy. Renal response was defined as a greater than 50% reduction in urinary protein excretion in the absence of a 25% or greater reduction in creatinine clearance. Complete hematologic response was defined as absence of detectable monoclonal protein in serum and urine and a bone marrow specimen containing less than 5% plasma cells without clonal dominance of kappa or lambda isotype. Among the 50 patients who survived for at least 12 months, proteinuria, hypoalbuminemia, and hypercholesterolemia improved during follow-up; 36% met criteria for a renal response. Median 24-hour urinary protein excretion decreased from a baseline value of 9.6 g/24 h to 1.6 g/24 h at 12 months among patients with complete hematologic response, and 71% met criteria for a renal response. Twenty-hour urinary protein excretion did not decrease during follow-up among patients with persistent plasma cell disease, and only 11% had a renal response at 12 months (P < 0.001 for hematologic responders vs. nonresponders). Dose-intensive intravenous melphalan with autologous blood stem-cell transplantation improves the nephrotic syndrome in patients with AL amyloidosis-associated renal disease. The benefit is largely limited to patients achieving eradication of the underlying plasma cell dyscrasia.

The effect of high-dose angiotensin II receptor blockade beyond maximal recommended doses in reducing urinary protein excretion.

The optimal doses of angiotensin-converting enzyme inhibitors (ACE-I) and/or angiotensin II receptor blockers (ARBs) for maximal reduction in urinary protein excretion are not known. Moreover, beneficial effects from ARBs, such as tissue protection owing to a more complete blockade of the renin-angiotensin-aldosterone system (RAAS), may be independent of blood pressure-lowering by ARBs. In this investigation, we evaluated whether increasing the dose of candesartan cilexetil, in subjects already on the maximally-recommended FDA doses of 32 mg, would induce a further reduction in 24-hour urinary protein excretion in patients with heavy proteinuria (urinary protein excretion >1.5 g/day; mean 4.4±2 g/day). Ten patients were started on 16 or 32 mg of candesartan cilexetil daily. After 1-2 months of therapy, the dose was titrated upwards to 96 mg. In all subjects, there were further reductions in 24-hour urinary protein excretion when the dose was increased beyond the recommended 32 mg maximal dose. Increasing the dose of candesartan cilexetil to 96 mg was safe, as most subjects showed no changes in serum potassium and, as expected, only a slight increase (0.5-0.7 mg/dl) in serum creatinine. These data warrant further investigation, since some subjects may require higher doses of candesartan to achieve optimal regression of proteinuria.

Impaired angiogenesis in the aging kidney: Vascular endothelial growth factor and thrombospondin-1 in renal disease

<h2>Abstract</h2> We investigated the relationship of changes in the microvasculature to age-related structural and functional changes in the kidney to determine whether there was evidence of impaired angiogenesis and whether the loss of microvasculature could be accounted for by changes in the local production of angiogenic or antiangiogenic factors. Glomerular and peritubular capillary number, density, and endothelial cell proliferation were determined in aging (24 months; n=9) and young (3 months; n=8) rat kidneys and correlated with renal functional and structural changes and alterations in renal expression of vascular endothelial growth factor (VEGF) and thrombospondin-1 (TSP-1). Aging rats showed a focal decrease in both peritubular capillary (peritubular capillary staining, 5.4% ± 1.8% versus 11.3% ± 2.0% per 100 tubules; rarefaction index, 10.6% ± 4.6% versus 0.6% ± 0.1%, aging versus young rats; <i>P</i> < 0.05 and <i>P</i> < 0.001, respectively) and glomerular capillary loops (27.3 ± 6.9 versus 50.7 ± 7.4/glomerulus, aging versus young rats; <i>P</i> < 0.001). The number of proliferating endothelial cells was decreased in aging rats compared with young rats (glomerular, 0.04 ± 0.01 versus 0.15 ± 0.03 positive cells/glomerular cross-section; peritubular, 0.7 ± 0.2 versus 4.3 ± 2.6 positive cells/mm²; <i>P</i> < 0.05). In the aging kidney, VEGF expression was focally increased in the cortex compared with young rats, whereas a profound decrease was observed in the outer and inner medulla (total area of VEGF expression, 19.2% ± 11.4% versus 39.3% ± 7.6%; <i>P</i> < 0.05). Tubular VEGF expression correlated with peritubular capillary density (<i>r²</i> = 0.57; <i>P</i> < 0.01) and inversely correlated with tubular osteopontin (<i>r²</i> = –0.55; <i>P</i> < 0.05) and macrophage infiltration (<i>r²</i> = –0.64; <i>P</i> < 0.01). TSP-1 staining was increased in the glomeruli and tubulointerstitium of the aging rats. Glomerular TSP-1 score correlated inversely with glomerular capillary number (<i>r²</i> = –0.89; <i>P</i> < 0.001). Tubulointerstitial TSP-1 also correlated with percentage of positive staining of peritubular capillary (<i>r²</i> = –0.59; <i>P</i> < 0.001). Glomerular capillary number showed significant correlation with glomerulosclerosis score, as well as with 24-hour urinary protein excretion. Peritubular capillary density also inversely correlated with interstitial fibrosis score and urinary protein excretion. In conclusion, glomerular and peritubular capillary loss in the aging kidney correlate with alterations in VEGF and TSP-1 expression and also with the development of glomerulosclerosis and tubulointerstitial fibrosis. These findings suggest that impaired angiogenesis associated with progressive loss in renal microvasculature may have a pivotal role in age-related nephropathy.

Impaired angiogenesis in the aging kidney: Vascular endothelial growth factor and Thrombospondin-1 in renal disease

We investigated the relationship of changes in the microvasculature to age-related structural and functional changes in the kidney to determine whether there was evidence of impaired angiogenesis and whether the loss of microvasculature could be accounted for by changes in the local production of angiogenic or antiangiogenic factors. Glomerular and peritubular capillary number, density, and endothelial cell proliferation were determined in aging (24 months; n = 9) and young (3 months; n = 8) rat kidneys and correlated with renal functional and structural changes and alterations in renal expression of vascular endothelial growth factor (VEGF) and thrombospondin-1 (TSP-1). Aging rats showed a focal decrease in both peritubular capillary (peritubular capillary staining, 5.4% ± 1.8% versus 11.3% ± 2.0% per 100 tubules; rarefaction index, 10.6% ± 4.6% versus 0.6% ± 0.1%, aging versus young rats; P < 0.05 and P < 0.001, respectively) and glomerular capillary loops (27.3 ± 6.9 versus 50.7 ± 7.4/glomerulus, aging versus young rats; P < 0.001). The number of proliferating endothelial cells was decreased in aging rats compared with young rats (glomerular, 0.04 ± 0.01 versus 0.15 ± 0.03 positive cells/glomerular cross-section; peritubular, 0.7 ± 0.2 versus 4.3 ± 2.6 positive cells/mm2; P < 0.05). In the aging kidney, VEGF expression was focally increased in the cortex compared with young rats, whereas a profound decrease was observed in the outer and inner medulla (total area of VEGF expression, 19.2% ± 11.4% versus 39.3% ± 7.6%; P < 0.05). Tubular VEGF expression correlated with peritubular capillary density (r2 = 0.57; P < 0.01) and inversely correlated with tubular osteopontin (r2 = –0.55; P < 0.05) and macrophage infiltration (r2 = –0.64; P < 0.01). TSP-1 staining was increased in the glomeruli and tubulointerstitium of the aging rats. Glomerular TSP-1 score correlated inversely with glomerular capillary number (r2 = –0.89; P < 0.001). Tubulointerstitial TSP-1 also correlated with percentage of positive staining of peritubular capillary (r2 = –0.59; P < 0.001). Glomerular capillary number showed significant correlation with glomerulosclerosis score, as well as with 24-hour urinary protein excretion. Peritubular capillary density also inversely correlated with interstitial fibrosis score and urinary protein excretion. In conclusion, glomerular and peritubular capillary loss in the aging kidney correlate with alterations in VEGF and TSP-1 expression and also with the development of glomerulosclerosis and tubulointerstitial fibrosis. These findings suggest that impaired angiogenesis associated with progressive loss in renal microvasculature may have a pivotal role in age-related nephropathy.

Suppression of Experimental Membranous Glomerulonephritis in Rats by an Anti-MHC Class II Antibody

Background: We previously reported that idiopathic membranous nephropathy (IMN) strongly correlated with HLA-DRB1*1501-DRB5*0101-DQAI*0102-DQB1* 0602, a specific haplotype of human major histocompatibility complex (MHC), in Japanese patients. To investigate the role of MHC in the development of rat Heymann nephritis (HN), an animal model of membranous nephropathy, a monoclonal antibody (mAb) specific to rat MHC class II antigen (RT1B) was administered, and its effectiveness in inhibiting HN was assessed. Methods: Active HN was induced in HN-sensitive Lewis rats by administering brush border proteins of rat proximal uriniferous tubules (FX1A). Rats were divided into four groups: rats treated with 1,000 µg anti-rat MHC class II mAb, rats treated with 100 µg anti-rat MHC class II mAb, rats treated with murine myeloma IgG, and rats that did not receive either FX1A or any other mAb. We examined the differences in 24-hour urinary protein excretion and serum alloantibody titers against FX1A between groups at different time intervals, and the histologic features of kidneys at the end of the study. Results: HN was induced in Lewis rats by inoculation with FX1A antigen. Administration of anti-MHC class II mAb successfully lowered urinary proteins, production of anti-FX1A alloantibodies, and the development of glomerular lesions in a dose-dependent manner. Conclusion: The present results demonstrated that the MHC class II molecule itself is directly involved in the pathogenesis of HN, and suggest that this therapy would be any better (or less toxic) than nonselective immunosuppressants in the treatment of IMN.

Lupus nephritis and the anti-phospholipid antibody syndrome in pregnancy

Lupus nephritis and the anti-phospholipid antibody syndrome in pregnancy

Effects of pulsatile intravenous insulin therapy on the progression of diabetic nephropathy

The purpose of this study was to assess the effects of pulsatile intravenous insulin therapy (PIVIT) on the progression of diabetic nephropathy in patients with type 1 diabetes mellitus (DM). This 18-month multicenter, prospective, controlled study involved 49 type 1 DM patients with nephropathy who were following the Diabetes Control and Complications Trial (DCCT) intensive therapy (IT) regimen. Of these, 26 patients formed the control group (C), which continued on IT, while 23 patients formed the treatment group (T) and underwent, in addition to IT, weekly PIVIT. Blood pressure in all patients was maintained below 140/90 mm Hg on antihypertensive medication, preferentially using angiotensin-converting enzyme (ACE) inhibitors. All study patients were seen in the clinic weekly for 18 months, had monthly glycohemoglobin (HbA1c), and every 3 months, 24-hour urinary protein excretion and creatinine clearance (CrCl) determinations. The HbA1c levels declined from 8.61% ± 0.33% to 7.68% ± 0.31% (P = .0028) in the T group and from 9.13% ± 0.36% to 8.19% ± 0.33% (P = .0015) in the C group during the study period. CrCl declined significantly in both groups, as expected, but the rate of CrCl decline in the T group (2.21 ± 1.62 mL/min/yr) was significantly less than in the C group (7.69 ± 1.88 mL/min/yr, P = .0343). We conclude that when PIVIT is added to IT in type 1 DM patients with overt nephropathy, it appears to markedly reduce the progression of diabetic nephropathy. The effect appears independent of ACE inhibitor therapy, blood pressure, or glycemic control. Copyright © 2000 by W.B. Saunders Company

Diabetes mellitus increases endothelin-1 gene transcription in rat kidney

Mesangial cell hypertrophy and increased extracellular matrix (ECM) contribute to mesangial expansion in early progressive diabetic nephropathy. Previous studies suggest that the growth factor endothelin-1 (ET-1) is not only up-regulated in diabetes, but may mediate the effects of hyperglycemia on mesangial cell hypertrophy and ECM synthesis. In models of diabetes mellitus, the mechanisms underlying increased ET-1 peptide and mRNA remain unknown. Therefore, our purpose is to determine whether ET-1 gene activity increases in kidneys of streptozotocin (SZT)-treated rats. Male Sprague-Dawley rats were injected with either SZT or vehicle. Parameters including glucose, body weight, 24-hour urine volume, urinary protein, and urinary ET-1 excretion were recorded. All rats were sacrificed at 12 weeks postinjection. Prepro-ET-1 mRNA from whole kidneys was determined using both RNase protection and reverse transcription-polymerase chain reaction (RT-PCR). The abundance of ET-1 peptide in primary cultured mesangial cells was detected by indirect immunofluorescence following treatment with 5.6, 11.2, or 22.5 mmol/L D-glucose for 24 hours. Cellular ET-1 mRNA was measured using RT-PCR in control cells at time 0 and also following exposure to increasing concentrations of glucose for 24 hours. Rat mesangial cells were transfected with a luciferase reporter construct containing the rat ET-1 promoter (pET1. Luc), and relative ET-1 promoter activity was measured after a 24-hour exposure to 5.6 and 22.5 mmol/L of D- or L-glucose. After 12 weeks of hyperglycemia, diabetic rats gained less weight (344 +/- 23.9 vs. 548.75 +/- 15.08 g), had increased urinary volume (158.6 +/- 24.32 vs. 8.38 +/- 1.56 mL/day), and had marked proteinuria (101.7 +/- 12.2 vs. 14.1 +/- 2.8 mg/day) compared with controls. Total urinary ET-1 peptide increased 26.4-fold in diabetic versus control rats (17.5083 +/- 5.405 vs. 0.6635 +/- 0.343 ng/day). ET-1 mRNA extracted from whole rat kidneys was increased 2.1-fold in diabetic versus control animals. Primary cultured rat mesangial cells demonstrated a significant increase in immunofluorescence labeling of ET-1 peptide and ET-1 mRNA in response to increasing concentrations of glucose. Furthermore, transfected mesangial cells exposed to 22.5 mmol/L D-glucose showed a 1.6-fold increase in ET-1 promoter activity relative to those treated with 5.6 mmol/L glucose. Glucose increases ET-1 gene expression in the kidney of the SZT-treated rat model of diabetes mellitus. Furthermore, high glucose induces ET-1 expression in primary cultured rat mesangial cells and directly enhances ET-1 promoter activity. The greater relative increase in peptide compared with transcription suggests the potential participation of other mechanisms such as increased mRNA stability, protein stability, and/or enhanced translational efficiency.

Renal function and blood pressure five years after Puumala virus-induced nephropathy

Nephropathia epidemica (NE) is a mild form of hemorrhagic fever with renal syndrome caused by Puumala hantavirus. Its long-term prognosis is considered favorable. Some reports suggest, however, that a previous hantavirus infection increases the risk of hypertension. We studied 46 previously healthy subjects (26 males and 20 females, mean age of 44 years) who had serologically confirmed NE three to seven years previously, and 38 healthy, seronegative controls (22 males and 16 females, mean age of 44 years). Ambulatory blood pressure (ABP) was monitored. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were determined by 51CrEDTA and 131I-hippurate clearances, respectively. The filtration fraction (FF) was calculated. Quantitative 24-hour urinary protein excretion (UprotE) and timed overnight urinary excretion of alpha1-microglobulin were measured. The NE patients had a higher mean ambulatory systolic BP than the controls (123 +/- 13 vs. 117 +/- 9 mm Hg, P = 0. 008). GFR and FF were increased in patients compared with controls (GFR, 120 +/- 20 vs. 109 +/- 14 mL/min/1.73 m2, P = 0.006; FF, 19 +/- 3 vs. 18 +/- 3%, P = 0.030), but ERPF did not differ between the groups. The patients also had higher UPE than the controls (median 0. 18 g/day, range 0.12 to 0.38 vs. median 0.14 g/day, range 0.09 to 0. 24, P < 0.001, respectively). The overnight urinary excretion rate of alpha1-microglobulin exceeded 7 microg/min in nine patients. Three to seven years after NE, the patients had higher GFR and FF, more proteinuria, and higher ambulatory systolic BP compared with the healthy controls. NE may thus cause mild renal lesions and alterations in BP in some patients.