Per-Ola Attman

Cadmium, mercury, and lead in kidney cortex of the general Swedish population: a study of biopsies from living kidney donors.

Cadmium, mercury, and lead concentrations were determined in deep-frozen kidney cortex biopsies taken from 36 living, healthy Swedish kidney donors (18 males and 18 females), who were 30-71 (mean 53) years of age. Information about occupation, smoking, the presence of dental amalgam, and fish consumption could be obtained for 27 of the donors. The samples (median dry weight 0.74 mg) were analyzed using inductively coupled plasma mass spectrometry, and the results were transformed to wet-weight concentrations. The median kidney Cd was 17 micrograms/g (95% confidence interval, 14-23 micrograms/g), which was similar in males and females. In 10 active smokers, the median kidney Cd was 24 micrograms/g, and in 12 who never smoked, it was 17 micrograms/g. The median kidney Hg was 0.29 micrograms/g, with higher levels in females (median 0.54 micrograms/g) than in males (median 0.16 micrograms/g). Subjects with amalgam fillings had higher kidney Hg (median 0.47 micrograms/g, n = 20) than those without dental amalgam (median 0.15 micrograms;g/g, n = 6), but kidney Hg was below the detection limit in some samples. Nearly half of the samples had kidney Pb below the detection limit. The median kidney Pb was estimated as 0. 14 micrograms/g. This is the first study of heavy metals in kidney cortex of living, healthy subjects, and the results are relatively similar to those of a few previous autopsy studies, indicating that results from autopsy cases are not seriously biased in relation to kidney metal concentrations in the general population. Cd concentrations in those who never smoked were relatively high, indicating considerable Cd intake from the diet in Sweden. The effect of dental amalgam on kidney Hg was as expected, although the reason for the difference in Hg levels between males and females is unclear. ImagesFigure 1

Influence of severe renal impairment on the pharmacokinetics and pharmacodynamics of oral ximelagatran and subcutaneous melagatran.

AbstractBackground: Ximelagatran is an oral direct thrombin inhibitor currently in clinical development as an anticoagulant for the prevention and treatment of thromboembolic disease. After oral administration, ximelagatran is rapidly absorbed and bioconverted to its active form, melagatran.n Objective: To investigate the effect of severe renal impairment on the pharmacokinetics and pharmacodynamics of melagatran following administration of subcutaneous melagatran and oral ximelagatran.n Study design: This was a nonblinded randomised crossover study with 2 study days, separated by a washout period of 1–3 weeks. Twelve volunteers with severe renal impairment and 12 controls with normal renal function were included, with median (range) glomerular filtration rates (GFR) of 13 (5–24) and 86 (70–105) mL/min, respectively. All volunteers received, in a randomised sequence, a 3mg subcutaneous injection of melagatran and a 24mg immediate-release tablet of ximelagatran. Blood samples were collected up to 12 and 14 hours after administration of the subcutaneous and oral doses, respectively, for determination of melagatran plasma concentrations and the activated partial thromboplastin time (APTT), an ex vivo measurement of coagulation time. Urine was collected for 24 hours after each dose for determination of melagatran concentration.n Results: For the volunteers with severe renal impairment, the area under the plasma concentration-time curve (AUC) and the half-life of melagatran were significantly higher than in the control group with normal renal function. Least-squares mean estimates of the ratios of the mean AUC for volunteers with severe renal impairment and controls (95% confidence intervals) were 4.03 (3.29–4.93) after subcutaneous melagatran and 5.33 (3.76–7.56) after oral ximelagatran. This result was related to the decreased renal clearance (CLr) of melagatran, which was linearly correlated with GFR. In the severe renal impairment and control groups, respectively, the mean CLr of melagatran was 12.5 and 81.3 mL/ min after subcutaneous administration of melagatran and 14.3 and 107 mL/min after oral administration of ximelagatran. There was a nonlinear relationship between the APTT ratio (postdose/predose APTT value) and melagatran plasma concentration. A statistically significant higher slope of the concentration-effect relationship, described by linear regression of the APTT ratio versus the square root of melagatran plasma concentrations, was estimated for the group with severe renal impairment compared to the control group; however, the increase in slope was minor and the estimated differences in APTT ratio between the groups in the studied concentration range was less than 10% and not considered clincially relevant. Ximelagatran and melagatran were well tolerated in both groups.n Conclusions: After administration of subcutaneous melagatran and oral ximelagatran, subjects with severe renal impairment had significantly higher melagatran exposure and longer half-life because of lower CLr of melagatran compared with the control group with normal renal function, suggesting that a decrease in dose and/or an increase in the administration interval in patients with severe renal impairment would be appropriate.

The effect of decreasing renal function on lipoprotein profiles

BACKGROUNDnProgressive chronic kidney disease (CKD) is accompanied by dyslipidemia that is characterized by increased concentrations of intact and partially metabolized ApoB and ApoC-III-containing triglyceride-rich lipoproteins in very low-density lipoprotein, intermediate density lipoprotein (IDL) and low-density lipoprotein. The purpose of the present study was to characterize the distribution of individual discrete lipoprotein subclasses in relation to the glomerular filtration rate (GFR) in nondiabetic CKD subjects.nnnMETHODSnFifty-one subjects (33 patients with CKD and 18 asymptomatic subjects) with GFR ranging from 12 to 120 mL/min were studied. Individual ApoA- and ApoB-containing lipoprotein subclasses (Lp) were determined in plasma by sequential immunoaffinity chromatography and subsequent determination of apolipoprotein composition by electroimmunoassays. GFR was measured as plasma clearance of iohexol or (51)Cr-ethylenediaminetetraacetic acid.nnnRESULTSnThere were no changes in concentrations of ApoA-containing lipoproteins with decreasing GFR. The levels of ApoB-containing lipoproteins increased significantly with decreasing GFR. There was a moderate increase of cholesterol-rich LpB and a 3-fold increase of ApoB- and ApoC-III-containing lipoproteins in subjects in the two lowest quintiles of GFR. This was accompanied by a significant increase of plasma ApoC-III.nnnCONCLUSIONSnReduced renal function is associated with a complex alteration of the lipoprotein profile that is predominantly characterized by increased concentrations of triglyceride-rich lipoprotein subclasses containing both ApoB and ApoC-III.

Oxidative stress and inflammation in renal patients and healthy subjects.

The first goal of this study was to measure the oxidative stress (OS) and relate it to lipoprotein variables in 35 renal patients before dialysis (CKD), 37 on hemodialysis (HD) and 63 healthy subjects. The method for OS was based on the ratio of cholesteryl esters (CE) containing C18/C16 fatty acids (R2) measured by gas chromatography (GC) which is a simple, direct, rapid and reliable procedure. The second goal was to investigate and identify a triacylglycerol peak on GC, referred to as TG48 (48 represents the sum of the three fatty acids carbon chain lengths) which was markedly increased in renal patients compared to healthy controls. We measured TG48 in patients and controls. Mass spectrometry (MS) and MS twice in tandem were used to analyze the fatty acid composition of TG48. MS showed that TG48 was abundant in saturated fatty acids (SFAs) that were known for their pro-inflammatory property. TG48 was significantly and inversely correlated with OS. Renal patients were characterized by higher OS and inflammation than healthy subjects. Inflammation correlated strongly with TG, VLDL-cholesterol, apolipoprotein (apo) C-III and apoC-III bound to apoB-containing lipoproteins, but not with either total cholesterol or LDL-cholesterol. In conclusion, we have discovered a new inflammatory factor, TG48. It is characterized with TG rich in saturated fatty acids. Renal patients have increased TG48 than healthy controls.

Plasma levels of lipoprotein (a) do not predict progression of human chronic renal failure

Chronic renal failure is frequently accompanied by elevated plasma levels of lipoprotein (a) [Lp(a)]. Elevated Lp(a) levels have been proposed to contribute not only to increased risk of atherosclerotic and thrombotic complications but also to the progression of renal insufficiency. To investigate whether higher Lp(a) plasma concentrations are associated with an accelerated rate of progression of renal insufficiency, we have correlated baseline plasma concentrations of Lp(a) with the progressive decline of renal function in an observational study of human chronic renal disease. Forty-nine non-diabetic patients (40 men, nine women) were studied as part of an observational study of patients with moderately advanced renal insufficiency. The average follow-up time of the patient population was 3.1 years, and the mean rate of decline in glomerular filtration rate (51Cr-EDTA clearance) was -2.8 (SD 4.1) ml/min/1.73 m2. The mean plasma concentration of Lp(a) at the beginning of the study was 19.2 (SD 18.6) mg/100 ml with a median value of 12.2 mg/100 ml. There was no association between the initial plasma concentration of Lp(a) and the rate of progression as assessed by linear regression analysis. Furthermore, the progression rate in patients within the highest quartile of the Lp(a) distribution (> or = 30 mg/100 ml) did not differ from that in patients with lower levels of Lp(a). In contrast, increased levels of apolipoprotein (apo) B, low-density lipoprotein (LDL)-cholesterol, and proteinuria were all significantly associated with a more rapid decline in renal function. Based on these results, it was concluded that elevated plasma levels of Lp(a) are not associated with an increased rate of progression of renal insufficiency in human chronic renal disease. However, the results of this study suggest that other apoB-containing lipoproteins may play a significant role in this process.

Diagnosis and classification of dyslipidemia in renal disease.

Renal disease is accompanied by specific alterations of the lipoprotein metabolism. While marked hyperlipidemia is a characteristic finding in the nephrotic syndrome, the dyslipoproteinemia of renal insufficiency is predominantly reflected in an abnormal apolipoprotein pattern but does not necessarily include elevated plasma lipid concentrations. The specific changes in nephrotic syndrome include increased formation primarily of cholesterol-rich and to a varying extent of triglyceride-rich ApoB-containing lipoproteins in the VLDL-LDL density range with little or no change among the ApoA-containing lipoproteins in HDL. The dyslipoproteinemia of renal failure is, on the other hand, mainly characterized by a decreased catabolism of the triglyceride-rich ApoB-containing lipoproteins with increased concentrations of partially metabolized lipoproteins of intermediate and very low density and a decreased concentration of ApoA-containing lipoproteins in HDL. In addition, increased levels of Lp(a) are found both in the nephrotic syndrome and in renal failure. Dialysis treatment appears to have only a modest influence on the renal dyslipoproteinemia. Due to its atherogenic character, the dyslipidemia of renal disease may be related to the accelerated development of cardiovascular disease in these patients.

A practical approach to low protein diets in Sweden– 45 years of clinical use

This review provides an overview of the development, implementation and practise of low protein diets (LPD) in Sweden. While the current practice is discussed in general terms emphasizing the interplay between nephrologists and dieticians, the ”self-selected” LPD model is explained as a practical approach to facilitated patient’s adherence to the nutritional therapy. This model is currently implemented in most clinics of the country and gives considerable flexibility regarding variation in meal planning, food selection, amounts consumed, cooking methods as well as adaptations to day-to-day changes. Current LPD use in Sweden is presented through analysis of the Swedish Renal Registry. Finally two patient cases are illustrated, with examples on their diets, attempts to reduce the protein content to the desired thresholds and their clinical course.