Gadolinium-induced nephrotoxicity.

Because of the well-documented risk of acute renal failure with the iodinated contrast media in patients with underlying chronic renal insufficiency, the use of intravenous gadolinium-based contrast media in magnetic resonance imaging for diagnostic and interventional radiology procedures has become a well-established clinical practice in the recent years. Although originally thought to be safe and lack the nephrotoxic effects of iodinated contrast media, gadolinium-based contrast media have recently been reported to induce a usually reversible decrease of glomerular filtration rate in a high-risk population group, especially in patients with altered baseline renal function. Here we present the current experimental and clinical evidence on this new challenge for the nephrologist, gadolinium-induced nephrotoxicity in patients with chronic kidney disease.

PPAR-gamma-agonists' renal effects.

PPAR-gamma ligands, including thiazolidinediones, have recently become clinically available for treating insulin-resistant diabetes mellitus. Accumulating evidence suggests that these drugs not only significantly improve insulin sensitivity but also may have antiproteinuric effects in genetically obese diabetic rodents and patients with type II diabetes and diabetic nephropathy. Moreover, troglitazone reduced expression of ECM proteins and transforming growth factor-beta in glomeruli from streptozotocin-induced diabetic rats. Many other properties including antiproteinuric, hemodynamic, and antihypertensive effects in insulin-dependent diabetes mellitus suggest that PPAR-gamma ligands might have a direct, beneficial renal effect, independent of their capacity to improve glucose tolerance. Besides their antidiabetic effects, thiazolidinediones have been shown to lower blood pressure in diabetic patients with hypertension and patients with diabetic nephropathy through multiple mechanisms. Several studies showed the efficacy of PPAR-gamma agonists to ameliorate the progression of glomerulosclerosis. The effect is independent of insulin effects and could only be partially due to lipid effects. These renal protective effects of PPAR-gamma agonists suggest that they may provide a novel intervention strategy to prevent vascular and glomerular sclerosis.

Successful renal transplantation decreases aortic stiffness and increases vascular reactivity in dialysis patients.

BACKGROUND: Patients with end-stage renal disease on dialysis have among the highest cardiovascular event rates documented. Abnormal nitric oxide (NO)-dependent endothelial reactivity and increased arterial stiffness are commonly described in hemodialysis (HD) patients. Measures of aortic stiffness--aortic pulse wave velocity (PWV) and augmentation index (AGI)--have been shown to be powerful predictors of survival on hemodialysis. It is not known how these parameters interfere with successful renal transplantation. METHODS: PWV and aortic AGI (difference between the first and second systolic peak on the aortic pressure waveform divided by the pulse wave height) were determined from contour analysis of arterial waveforms recorded by applanation tonometry using a SphygmoCor device in 41 HD patients (20 men; age, 41.8 years) and in a control group of 20 patients with essential hypertension (HTA) (10 men; age, 43.6 years). Twenty of the HD patients (10 men; age, 39.7 years) received live-related renal transplants (RTx) and were restudied (3 months after RTx, normal serum creatinine). NO-dependent and NO-independent vascular reactivity were assessed by changes in AGI after challenges with inhaled salbutamol (SAL) and sublingual nitroglycerin (NTG), respectively. RESULTS: AGI values were significantly lower in RTx patients compared with subjects on hemodialysis (15.9 +/- 13.9% vs. 27.9 +/- 11.9%, P<0.05), but similar to essential HTA controls (16.5 +/- 17%). Serial AGI measurements showed that successful renal transplantation is associated with a decrease in AGI in all cases, from a mean of 25.1 +/- 7.8% while on dialysis to 15.9 +/- 7.0% 3 months after transplantation (P<0.0001). The responsiveness to both endothelium-dependent stimuli (inhaled SAL) and endothelium-independent stimuli (sublingual NTG) was greater in transplant patients than in hemodialysis patients (SAL-induced decrease in AGI -82.3 +/- 65.7% vs. 45 +/- 72.3%, P<0.01; and NTG-induced decrease in AGI 197 +/- 108 vs. -129.0 +/- 215.5%, P<0.01). PWV values in dialysis patients (7.19 +/- 1.88 m/sec) were significantly higher than those measured in essential HTA patients (6.34 +/- 1.32 m/sec, P<0.05) with normal renal function (despite similar blood pressure levels). PWV after RTx was 6.59 +/- 1.62 m/sec, significantly different from pretransplantation (dialysis) values (P<0.05 for comparison) but similar to the control group of essential HTA patients. CONCLUSIONS: Renal transplantation is associated with marked improvements in vascular structure and function to a profile comparable to essential HTA patients.

Cardiac troponins in renal failure - time for an optimistic consensus?

Elevated cardiac troponin concentrations are now accepted as the gold standard biochemical markers for the diagnosis of myocardial damage in patients with unstable coronary syndromes, having also a demonstrated value in early risk stratification and in adopting different therapeutic strategies. The specificity and sensitivity of cardiac troponins for diagnosis of acute coronary diseases in renal failure have been a point of confusion over the past decade, mainly because of moderate elevations of these cardiac biomarkers, commonly observed in patients with chronic renal dysfunction and without any significant myocardial damage. This review discusses the cardiac troponins, their biochemistry, their currently accepted cut-off values and their real significance in chronic renal failure (CRF), concluding that troponins maintain their diagnostic and prognostic values in patients with CRF, being predictive not only of cardiovascular mortality but also of general mortality in this patient group.