Systematic analysis of the intravoxel incoherent motion threshold separating perfusion and diffusion effects: Proposal of a standardized algorithm

PURPOSE To systematically evaluate the dependence of intravoxel-incoherent-motion (IVIM) parameters on the b-value threshold separating the perfusion and diffusion compartment, and to implement and test an algorithm for the standardized computation of this threshold. METHODS Diffusion weighted images of the upper abdomen were acquired at 3 Tesla in eleven healthy male volunteers with 10 different b-values and in two healthy male volunteers with 16 different b-values. Region-of-interest IVIM analysis was applied to the abdominal organs and skeletal muscle with a systematic increase of the b-value threshold for computing pseudodiffusion D*, perfusion fraction Fp , diffusion coefficient D, and the sum of squared residuals to the bi-exponential IVIM-fit. RESULTS IVIM parameters strongly depended on the choice of the b-value threshold. The proposed algorithm successfully provided optimal b-value thresholds with the smallest residuals for all evaluated organs [s/mm2]: e.g., right liver lobe 20, spleen 20, right renal cortex 150, skeletal muscle 150. Mean D* [10(-3) mm(2) /s], Fp [%], and D [10(-3) mm(2) /s] values (±standard deviation) were: right liver lobe, 88.7 ± 42.5, 22.6 ± 7.4, 0.73 ± 0.12; right renal cortex: 11.5 ± 1.8, 18.3 ± 2.9, 1.68 ± 0.05; spleen: 41.9 ± 57.9, 8.2 ± 3.4, 0.69 ± 0.07; skeletal muscle: 21.7 ± 19.0; 7.4 ± 3.0; 1.36 ± 0.04. CONCLUSION IVIM parameters strongly depend upon the choice of the b-value threshold used for computation. The proposed algorithm may be used as a robust approach for IVIM analysis without organ-specific adaptation. Magn Reson Med, 2014. © 2014 Wiley Periodicals, Inc.

First report of the Global SYMPLICITY Registry on the effect of renal artery denervation in patients with uncontrolled hypertension.

UNLABELLED This study aimed to assess the safety and effectiveness of renal denervation using the Symplicity system in real-world patients with uncontrolled hypertension (NCT01534299). The Global SYMPLICITY Registry is a prospective, open-label, multicenter registry. Office and 24-hour ambulatory blood pressures (BPs) were measured. Change from baseline to 6 months was analyzed for all patients and for subgroups based on baseline office systolic BP, diabetic status, and renal function; a cohort with severe hypertension (office systolic pressure, ≥160 mm Hg; 24-hour systolic pressure, ≥135 mm Hg; and ≥3 antihypertensive medication classes) was also included. The analysis included protocol-defined safety events. Six-month outcomes for 998 patients, including 323 in the severe hypertension cohort, are reported. Mean baseline office systolic BP was 163.5±24.0 mm Hg for all patients and 179.3±16.5 mm Hg for the severe cohort; the corresponding baseline 24-hour mean systolic BPs were 151.5±17.0 and 159.0±15.6 mm Hg. At 6 months, the changes in office and 24-hour systolic BPs were -11.6±25.3 and -6.6±18.0 mm Hg for all patients (P<0.001 for both) and -20.3±22.8 and -8.9±16.9 mm Hg for those with severe hypertension (P<0.001 for both). Renal denervation was associated with low rates of adverse events. After the procedure through 6 months, there was 1 new renal artery stenosis >70% and 5 cases of hospitalization for a hypertensive emergency. In clinical practice, renal denervation resulted in significant reductions in office and 24-hour BPs with a favorable safety profile. Greater BP-lowering effects occurred in patients with higher baseline pressures. CLINICAL TRIAL REGISTRATION URL: www.clinicaltrials.gov. Unique identifier: NCT01534299.

Sphingosine kinase 2 deficiency increases proliferation and migration of renal mouse mesangial cells and fibroblasts

Both of the sphingosine kinase (SK) subtypes SK-1 and SK-2 catalyze the production of the bioactive lipid molecule sphingosine 1-phosphate (S1P). However, the subtype-specific cellular functions are largely unknown. In this study, we investigated the cellular function of SK-2 in primary mouse renal mesangial cells (mMC) and embryonic fibroblasts (MEF) from wild-type C57BL/6 or SK-2 knockout (SK2ko) mice. We found that SK2ko cells displayed a significantly higher proliferative and migratory activity when compared to wild-type cells, with concomitant increased cellular activities of the classical extracellular signal regulated kinase (ERK) and PI3K/Akt cascades, and of the small G protein RhoA. Furthermore, we detected an upregulation of SK-1 protein and S1P3 receptor mRNA expression in SK-2ko cells. The MEK inhibitor U0126 and the S1P1/3 receptor antagonist VPC23019 blocked the increased migration of SK-2ko cells. Additionally, S1P3ko mesangial cells showed a reduced proliferative behavior and reduced migration rate upon S1P stimulation, suggesting a crucial involvement of the S1P3 receptor. In summary, our data demonstrate that SK-2 exerts suppressive effects on cell growth and migration in renal mesangial cells and fibroblasts, and that therapeutic targeting of SKs for treating proliferative diseases requires subtype-selective inhibitors.

Cellular and molecular effects of the mTOR inhibitor everolimus.

mTOR (mechanistic target of rapamycin) functions as the central regulator for cell proliferation, growth and survival. Up-regulation of proteins regulating mTOR, as well as its downstream targets, has been reported in various cancers. This has promoted the development of anti-cancer therapies targeting mTOR, namely fungal macrolide rapamycin, a naturally occurring mTOR inhibitor, and its analogues (rapalogues). One such rapalogue, everolimus, has been approved in the clinical treatment of renal and breast cancers. Although results have demonstrated that these mTOR inhibitors are effective in attenuating cell growth of cancer cells under in vitro and in vivo conditions, subsequent sporadic response to rapalogues therapy in clinical trials has promoted researchers to look further into the complex understanding of the dynamics of mTOR regulation in the tumour environment. Limitations of these rapalogues include the sensitivity of tumour subsets to mTOR inhibition. Additionally, it is well known that rapamycin and its rapalogues mediate their effects by inhibiting mTORC (mTOR complex) 1, with limited or no effect on mTORC2 activity. The present review summarizes the pre-clinical, clinical and recent discoveries, with emphasis on the cellular and molecular effects of everolimus in cancer therapy.

Analysis of prognostic factors for the development of metastases and survival in renal cell carcinoma patients

Introduction and objective. A number of prognostic factors have been reported for predicting survival in patients with renal cell carcinoma. Yet few studies have analyzed the effects of those factors at different stages of the disease process. In this study, different stages of disease progression starting from nephrectomy to metastasis, from metastasis to death, and from evaluation to death were evaluated. ^ Methods. In this retrospective follow-up study, records of 97 deceased renal cell carcinoma (RCC) patients were reviewed between September 2006 to October 2006. Patients with TNM Stage IV disease before nephrectomy or with cancer diagnoses other than RCC were excluded leaving 64 records for analysis. Patient TNM staging, Furhman Grade, age, tumor size, tumor volume, histology and patient gender were analyzed in relation to time to metastases. Time from nephrectomy to metastasis, TNM staging, Furhman Grade, age, tumor size, tumor volume, histology and patient gender were tested for significance in relation to time from metastases to death. Finally, analysis of laboratory values at time of evaluation, Eastern Cooperative Oncology Group performance status (ECOG), UCLA Integrated Staging System (UISS), time from nephrectomy to metastasis, TNM staging, Furhman Grade, age, tumor size, tumor volume, histology and patient gender were tested for significance in relation to time from evaluation to death. Linear regression and Cox Proportional Hazard (univariate and multivariate) was used for testing significance. Kaplan-Meier Log-Rank test was used to detect any significance between groups at various endpoints. ^ Results. Compared to negative lymph nodes at time of nephrectomy, a single positive lymph node had significantly shorter time to metastasis (p<0.0001). Compared to other histological types, clear cell histology had significant metastasis free survival (p=0.003). Clear cell histology compared to other types (p=0.0002 univariate, p=0.038 multivariate) and time to metastasis with log conversion (p=0.028) significantly affected time from metastasis to death. A greater than one year and greater than two year metastasis free interval, compared to patients that had metastasis before one and two years, had statistically significant survival benefit (p=0.004 and p=0.0318). Time from evaluation to death was affected by greater than one year metastasis free interval (p=0.0459), alcohol consumption (p=0.044), LDH (p=0.006), ECOG performance status (p<0.001), and hemoglobin level (p=0.0092). The UISS risk stratified the patient population in a statistically significant manner for survival (p=0.001). No other factors were found to be significant. ^ Conclusion. Clear cell histology is predictive for both time to metastasis and metastasis to death. Nodal status at time of nephrectomy may predict risk of metastasis. The time interval to metastasis significantly predicts time from metastasis to death and time from evaluation to death. ECOG performance status, and hemoglobin levels predicts survival outcome at evaluation. Finally, UISS appropriately stratifies risk in our population. ^

Role of obesity, weight gain, physical activity, and polymorphisms in the mTOR pathway and the risk of renal cell carcinoma

The interplay between obesity, physical activity, weight gain and genetic variants in mTOR pathway have not been studied in renal cell carcinoma (RCC). We examined the associations between obesity, weight gain, physical activity and RCC risk. We also analyzed whether genetic variants in the mTOR pathway could modify the association. Incident renal cell carcinoma cases and healthy controls were recruited from the University of Texas MD Anderson Cancer Center in Houston, Texas. Cases and controls were frequency-matched by age (±5 years), ethnicity, sex, and county of residence. Epidemiologic data were collected via in-person interview. A total of 577 cases and 593 healthy controls (all white) were included. One hundred ninety-two (192) SNPs from 22 genes were available and their genotyping data were extracted from previous genome-wide association studies. Logistic regression and regression spline were performed to obtain odds ratios. Obesity at age 20, 40, and 3 years prior to diagnosis/recruitment, and moderate and large weight gain from age 20 to 40 were each significantly associated with increased RCC risk. Low physical activity was associated with a 4.08-fold (95% CI: 2.92-5.70) increased risk. Five single nucleotide polymorphisms (SNPs) were significantly associated with RCC risk and their cumulative effect increased the risk by up to 72% (95% CI: 1.20-2.46). Strata specific effects for weight change and genotyping cumulative groups were observed. However, no interaction was suggested by our study. In conclusion, energy balance related risk factors and genetic variants in the mTOR pathway may jointly influence susceptibility to RCC. ^

Effects of overweight and obesity on economic outcomes among U.S. adults with kidney disease

Background. Kidney disease is a growing public health phenomenon in the U.S. and in the world. Downstream interventions, dialysis and renal transplants covered by Medicare's renal disease entitlement policy in those who are 65 years and over have been expensive treatments that have been not foolproof. The shortage of kidney donors in the U.S. has grown in the last two decades. Therefore study of upstream events in kidney disease development and progression is justified to prevent the rising prevalence of kidney disease. Previous studies have documented the biological route by which obesity can progress and accelerate kidney disease, but health services literature on quantifying the effects of overweight and obesity on economic outcomes in the context of renal disease were lacking. Objectives . The specific aims of this study were (1) to determine the likelihood of overweight and obesity in renal disease and in three specific adult renal disease sub-populations, hypertensive, diabetic and both hypertensive and diabetic (2) to determine the incremental health service use and spending in overweight and obese renal disease populations and (3) to determine who financed the cost of healthcare for renal disease in overweight and obese adult populations less than 65 years of age. Methods. This study was a retrospective cross-sectional study of renal disease cases pooled for years 2002 to 2009 from the Medical Expenditure Panel Survey. The likelihood of overweight and obesity was estimated using chi-square test. Negative binomial regression and generalized gamma model with log link were used to estimate healthcare utilization and healthcare expenditures for six health event categories. Payments by self/family, public and private insurance were described for overweight and obese kidney disease sub-populations. Results. The likelihood of overweight and obesity was 0.29 and 0.46 among renal disease and obesity was common in hypertensive and diabetic renal disease population. Among obese renal disease population, negative binomial regression estimates of healthcare utilization per person per year as compared to normal weight renal disease persons were significant for office-based provider visits and agency home health visits respectively (p=0.001; p=0.005). Among overweight kidney disease population health service use was significant for inpatient hospital discharges (p=0.027). Over years 2002 to 2009, overweight and obese renal disease sub-populations had 53% and 63% higher inpatient facility and doctor expenditures as compared to normal weight renal disease population and these result were statistically significant (p=0.007; p=0.026). Overweigh renal disease population had significant total expenses per person per year for office-based and outpatient associated care. Overweight and obese renal disease persons paid less from out-of-pocket overall compared to normal weight renal disease population. Medicare and Medicaid had the highest mean annual payments for obese renal disease persons, while mean annual payments per year were highest for private insurance among normal weight renal disease population. Conclusion. Overweight and obesity were common in those with acute and chronic kidney disease and resulted in higher healthcare spending and increased utilization of office-based providers, hospital inpatient department and agency home healthcare. Healthcare for overweight and obese renal disease persons younger than 65 years of age was financed more by private and public insurance and less by out of pocket payments. With the increasing epidemic of obesity in the U.S. and the aging of the baby boomer population, the findings of the present study have implications for public health and for greater dissemination of healthcare resources to prevent, manage and delay the onset of overweight and obesity that can progress and accelerate the course of the kidney disease.^

CTLA4-Ig and anti-CD40 ligand prevent renal allograft rejection in primates

Selective inhibition of T cell costimulation using the B7-specific fusion protein CTLA4-Ig has been shown to induce long-term allograft survival in rodents. Antibodies preventing the interaction between CD40 and its T cell-based ligand CD154 (CD40L) have been shown in rodents to act synergistically with CTLA4-Ig. It has thus been hypothesized that these agents might be capable of inducing long-term acceptance of allografted tissues in primates. To test this hypothesis in a relevant preclinical model, CTLA4-Ig and the CD40L-specific monoclonal antibody 5C8 were tested in rhesus monkeys. Both agents effectively inhibited rhesus mixed lymphocyte reactions, but the combination was 100 times more effective than either drug alone. Renal allografts were transplanted into nephectomized rhesus monkeys shown to be disparate at major histocompatibility complex class I and class II loci. Control animals rejected in 5–8 days. Brief induction doses of CTLA4-Ig or 5C8 alone significantly prolonged rejection-free survival (20–98 days). Two of four animals treated with both agents experienced extended (>150 days) rejection-free allograft survival. Two animals treated with 5C8 alone and one animal treated with both 5C8 and CTLA4-Ig experienced late, biopsy-proven rejection, but a repeat course of their induction regimen successfully restored normal graft function. Neither drug affected peripheral T cell or B cell counts. There were no clinically evident side effects or rejections during treatment. We conclude that CTLA4-Ig and 5C8 can both prevent and reverse acute allograft rejection, significantly prolonging the survival of major histocompatibility complex-mismatched renal allografts in primates without the need for chronic immunosuppression.

Mutations in a NIMA-related kinase gene, Nek1, cause pleiotropic effects including a progressive polycystic kidney disease in mice

We previously have described a mouse model for polycystic kidney disease (PKD) caused by either of two mutations, kat or kat2J, that map to the same locus on chromosome 8. The homozygous mutant animals have a latent onset, slowly progressing form of PKD with renal pathology similar to the human autosomal-dominant PKD. In addition, the mutant animals show pleiotropic effects that include facial dysmorphism, dwarfing, male sterility, anemia, and cystic choroid plexus. We previously fine-mapped the kat2J mutation to a genetic distance of 0.28 ± 0.12 centimorgan between D8Mit128 and D8Mit129. To identify the underlying molecular defect in this locus, we constructed an integrated genetic and physical map of the critical region surrounding the kat2J mutation. Cloning and expression analysis of the transcribed sequences from this region identified Nek1, a NIMA (never in mitosis A)-related kinase as a candidate gene. Further analysis of the Nek1 gene from both kat/kat and kat2J/kat2J mutant animals identified a partial internal deletion and a single-base insertion as the molecular basis for these mutations. The complex pleiotropic phenotypes seen in the homozygous mutant animals suggest that the NEK1 protein participates in different signaling pathways to regulate diverse cellular processes. Our findings identify a previously unsuspected role for Nek1 in the kidney and open a new avenue for studying cystogenesis and identifying possible modes of therapy.

Factors affecting counteraction by methylamines of urea effects on aldose reductase

The concentration of urea in renal medullary cells is high enough to affect enzymes seriously by reducing Vmax or raising Km, yet the cells survive and function. The usual explanation is that the methylamines found in the renal medulla, namely glycerophosphocholine and betaine, have actions opposite to those of urea and thus counteract its effects. However, urea and methylamines have the similar (not counteracting) effects of reducing both the Km and Vmax of aldose reductase (EC 1.1.1.21), an enzyme whose function is important in renal medullas. Therefore, we examined factors that might determine whether counteraction occurs, namely different combinations of assay conditions (pH and salt concentration), methylamines (glycerophosphocholine, betaine, and trimethylamine N-oxide), substrates (dl-glyceraldehyde and d-xylose), and a mutation in recombinant aldose reductase protein (C298A). We find that Vmax of both wild-type and C298A mutant generally is reduced by urea and/or the methylamines. However, the effects on Km are much more complex, varying widely with the combination of conditions. At one extreme, we find a reduction of Km of wild-type enzyme by urea and/or methylamines that is partially additive, whereas at the other extreme we find that urea raises Km for d-xylose of the C298A mutant, betaine lowers the Km, and the two counteract in a classical fashion so that at a 2:1 molar ratio of betaine to urea there is no net effect. We conclude that counteraction of urea effects on enzymes by methylamines can depend on ion concentration, pH, the specific methylamine and substrate, and identity of even a single amino acid in the enzyme.

Human renal cell carcinoma expresses distinct binding sites for growth hormone-releasing hormone

Antagonists of growth hormone-releasing hormone (GHRH) inhibit the proliferation of various human cancers in vitro and in vivo by mechanisms that include apparent direct effects through specific binding sites expressed on tumors and that differ from pituitary human GHRH (hGHRH) receptors. In this study, GHRH antagonist JV-1–38 (20 μg/day per animal s.c.) inhibited the growth of orthotopic CAKI-1 human renal cell carcinoma (RCC) by 83% and inhibited the development of metastases to lung and lymph nodes. Using ligand competition assays with 125I-labeled GHRH antagonist JV-1–42, we demonstrated the presence of specific high-affinity (Kd = 0.25 ± 0.03 nM) binding sites for GHRH with a maximal binding capacity (Bmax) of 70.2 ± 4.1 fmol/mg of membrane protein in CAKI-1 tumors. These receptors bind GHRH antagonists preferentially and display a lower affinity for hGHRH. The binding of 125I-JV-1–42 is not inhibited by vasoactive intestinal peptide (VIP)-related peptides sharing structural homology with hGHRH. The receptors for GHRH antagonists on CAKI-1 tumors are distinct from binding sites detected with 125I-VIP (Kd = 0.89 ± 0.14 nM; Bmax = 183.5 ± 2.6 fmol/mg of protein) and also have different characteristics from GHRH receptors on rat pituitary as documented by the insignificant binding of [His1,125I-Tyr10,Nle27]hGHRH(1–32)NH2. Reverse transcription-PCR revealed the expression of splice variants of hGHRH receptor in CAKI-1 RCC. Biodistribution studies demonstrate an in vivo uptake of 125I-JV-1–42 by the RCC tumor tissue. The presence of specific receptor proteins that bind GHRH antagonists in CAKI-1 RCC supports the view that distinct binding sites that mediate the inhibitory effect of GHRH antagonists are present on various human cancers.

Direct toxicity of nonsteroidal antiinflammatory drugs for renal medullary cells

Antipyretic analgesics, taken in large doses over a prolonged period, cause a specific form of kidney disease, characterized by papillary necrosis and interstitial scarring. Epidemiological evidence incriminated mixtures of drugs including aspirin (ASA), phenacetin, and caffeine. The mechanism of toxicity is unclear. We tested the effects of ASA, acetaminophen (APAF, the active metabolite of phenacetin), caffeine, and other related drugs individually and in combination on mouse inner medullary collecting duct cells (mIMCD3). The number of rapidly proliferating cells was reduced by ≈50% by 0.5 mM ASA, salicylic acid, or APAF. The drugs had less effect on confluent cells, which proliferate slowly. Thus, the slow in vivo turnover of IMCD cells could explain why clinical toxicity requires very high doses of these drugs over a very long period. Caffeine greatly potentiated the effect of acetaminophen, pointing to a potential danger of the mixture. Cyclooxygenase (COX) inhibitors, indomethacin and NS-398, did not reduce cell number except at concentrations greatly in excess of those that inhibit COX. Therefore, COX inhibition alone is not toxic. APAF arrests most cells in late G1 and S and produces a mixed form of cell death with both oncosis (swollen cells and nuclei) and apoptosis. APAF is known to inhibit the synthesis of DNA and cause chromosomal aberrations due to inhibition of ribonucleotide reductase. Such effects of APAF might account for renal medullary cell death in vivo and development of uroepithelial tumors from surviving cells that have chromosomal aberrations.

Rapid activation of Na+/H+ exchange by aldosterone in renal epithelial cells requires Ca2+ and stimulation of a plasma membrane proton conductance.

There is increasing evidence for an additional acute, nongenomic action of the mineralocorticoid hormone aldosterone on renal epithelial cells, leading to a two-step model of mineralocorticoid action on electrolyte excretion. We investigated the acute effect of aldosterone on intracellular free Ca2+ and on intracellular pH in an aldosterone-sensitive Madin-Darby canine kidney cell clone. Within seconds of application of aldosterone, but not of the glucocorticoid hydrocortisone, there was a 3-fold sustained increase of intracellular Ca2+ at a half-maximal concentration of 10(-10) mol/liter. Omission of extracellular Ca2+ prevented this hormone response. In the presence of extracellular Ca2+ aldosterone led to intracellular alkalinization. The Na+/H+ exchange inhibitor ethyl-isopropanol-amiloride (EIPA) prevented the aldosterone-induced alkalinization but not the aldosterone-induced increase of intracellular Ca2+. Omission of extracellular Ca2+ also prevented aldosterone-induced alkalinization. Instead, aldosterone led to a Zn(2+)-dependent intracellular acidification in the presence of EIPA, indicative of an increase of plasma membrane proton conductance. Under control conditions, Zn2+ prevented the aldosterone-induced alkalinization completely. We conclude that aldosterone stimulated net-entry of Ca2+ from the extracellular compartment and a plasma membrane H+ conductance as prerequisites for the stimulation of plasma membrane Na+/H+ exchange which in turn modulates K+ channel acitivity. It is probable that the aldosterone-sensitive H+ conductance maintains Na+/H+ exchange activity by providing an acidic environment in the vicinity of the exchanger. Thus, genomic action of aldosterone determines cellular transport equipment, whereas the nongenomic action regulates transporter activity that requires responses within seconds or minutes, which explains the rapid effects on electrolyte excretion.

In vivo suppression of the renal Na+/Pi cotransporter by antisense oligonucleotides.

A 20-mer phosphorothioate oligonucleotide (AS1) was designed to hybridize to the message for the rat kidney sodium phosphate cotransporter NaPi-2 close to the translation initiation site. Single intravenous doses of this oligonucleotide were given to rats maintained on a low phosphorus diet to increase NaPi-2 expression. At 3 days after oligonucleotide infusion, rats receiving 2.5 micromol of AS1 exhibited a reduction in renal NaPi-2 to cyclophilin mRNA ratio by 40% +/- 17%, and rats receiving 7.5 micromol of AS1 exhibited a reduction in NaPi-2 to cyclophilin mRNA ratio by 46% +/- 21%. Reversed-sequence AS1 was without effect. The higher dose of 7.5 micromol of AS1 also reduced the rate of phosphate uptake into renal brush border membrane vesicles and the expression of NaPi-2 protein detected by Western blotting in these vesicles. Reversed sequence AS1 was again without effect on these parameters. These results suggest that systemically infused oligonucleotides can exert antisense effects in the renal proximal tubule.

Prevention of cardiovascular and renal pathology of aging by the advanced glycation inhibitor aminoguanidine.

Human aging is impacted severely by cardiovascular disease and significantly but less overtly by renal dysfunction. Advanced glycation endproducts (AGEs) have been linked to tissue damage in diabetes and aging, and the AGE inhibitor aminoguanidine (AG) has been shown to inhibit renal and vascular pathology in diabetic animals. In the present study, the effects of AG on aging-related renal and vascular changes and AGE accumulation were studied in nondiabetic female Sprague-Dawley (S-D) and Fischer 344 (F344) rats treated with AG (0.1% in drinking water) for 18 mo. Significant increases in the AGE content in aged cardiac (P < 0.05), aortic (P < 0.005), and renal (P < 0.05) tissues were prevented by AG treatment (P < 0.05 for each tissue). A marked age-linked vasodilatory impairment in response to acetylcholine and nitroglycerine was prevented by AG treatment (P < 0.005), as was an age-related cardiac hypertrophy evident in both strains (P < 0.05). While creatinine clearance was unaffected by aging in these studies, the AGE/ creatinine clearance ratio declined 3-fold in old rats vs. young rats (S-D, P < 0.05; F344, P < 0.01), while it declined significantly less in AG-treated old rats (P < 0.05). In S-D but not in F344 rats, a significant (P < 0.05) age-linked 24% nephron loss was completely prevented by AG treatment, and glomerular sclerosis was markedly suppressed (P < 0.01). Age-related albuminuria and proteinuria were markedly inhibited by AG in both strains (S-D, P < 0.01; F344, P < 0.01). These data suggest that early interference with AGE accumulation by AG treatment may impart significant protection against the progressive cardiovascular and renal decline afflicting the last decades of life.