The association between TMAO, CMPF, and clinical outcomes in advanced chronic kidney disease: results from the European QUALity (EQUAL) Study

BACKGROUND

Trimethylamine N-oxide (TMAO), a metabolite from red meat and fish consumption, plays a role in promoting cardiovascular events. However, data regarding TMAO and its impact on clinical outcomes are inconclusive, possibly due to its undetermined dietary source.

OBJECTIVES

We hypothesized that circulating TMAO derived from fish intake might cause less harm compared with red meat sources by examining the concomitant level of 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF), a known biomarker of fish intake, and investigated the association between TMAO, CMPF, and outcomes.

METHODS

Patients were recruited from the European QUALity (EQUAL) Study on treatment in advanced chronic kidney disease among individuals aged ≥65 y whose estimated glomerular filtration rate (eGFR) had dropped for the first time to ≤20 mL/min per 1.73 m2 during the last 6 mo. The association between TMAO, CMPF, and outcomes including all-cause mortality and kidney replacement therapy (KRT) was assessed among 737 patients. Patients were further stratified by median cutoffs of TMAO and CMPF, suggesting high/low red meat and fish intake.

RESULTS

During a median of 39 mo of follow-up, 232 patients died. Higher TMAO was independently associated with an increased risk of all-cause mortality (multivariable HR: 1.46; 95% CI: 1.17, 1.83). Higher CMPF was associated with a reduced risk of both all-cause mortality (HR: 0.79; 95% CI: 0.71, 0.89) and KRT (HR: 0.80; 95% CI: 0.71, 0.90), independently of TMAO and other clinically relevant confounders. In comparison to patients with low TMAO and CMPF, patients with low TMAO and high CMPF had reduced risk of all-cause mortality (adjusted HR: 0.49; 95% CI: 0.31, 0.73), whereas those with high TMAO and high CMPF showed no association across adjusted models.

CONCLUSIONS

High CMPF conferred an independent role in health benefits and might even counteract the unfavorable association between TMAO and outcomes. Whether higher circulating CMPF concentrations are due to fish consumption, and/or if CMPF is a protective factor, remains to be verified.

Associations between depressive symptoms and disease progression in older patients with chronic kidney disease: results of the EQUAL study

Background

Depressive symptoms are associated with adverse clinical outcomes in patients with end-stage kidney disease; however, few small studies have examined this association in patients with earlier phases of chronic kidney disease (CKD). We studied associations between baseline depressive symptoms and clinical outcomes in older patients with advanced CKD and examined whether these associations differed depending on sex.

Methods

CKD patients (≥65 years; estimated glomerular filtration rate ≤20 mL/min/1.73 m²) were included from a European multicentre prospective cohort between 2012 and 2019. Depressive symptoms were measured by the five-item Mental Health Inventory (cut-off ≤70; 0–100 scale). Cox proportional hazard analysis was used to study associations between depressive symptoms and time to dialysis initiation, all-cause mortality and these outcomes combined. A joint model was used to study the association between depressive symptoms and kidney function over time. Analyses were adjusted for potential baseline confounders.

Results

Overall kidney function decline in 1326 patients was –0.12 mL/min/1.73 m²/month. A total of 515 patients showed depressive symptoms. No significant association was found between depressive symptoms and kidney function over time (P = 0.08). Unlike women, men with depressive symptoms had an increased mortality rate compared with those without symptoms [adjusted hazard ratio 1.41 (95% confidence interval 1.03–1.93)]. Depressive symptoms were not significantly associated with a higher hazard of dialysis initiation, or with the combined outcome (i.e. dialysis initiation and all-cause mortality).

Conclusions

There was no significant association between depressive symptoms at baseline and decline in kidney function over time in older patients with advanced CKD. Depressive symptoms at baseline were associated with a higher mortality rate in men.

The relationship between uremic toxins and symptoms in older men and women with advanced chronic kidney disease

Background

Patients with stage 4/5 chronic kidney disease (CKD) suffer from various symptoms. The retention of uremic solutes is thought to be associated with those symptoms. However, there are relatively few rigorous studies on the potential links between uremic toxins and symptoms in patients with CKD.

Methods

The EQUAL study is an ongoing observational cohort study of non-dialyzed patients with stage 4/5 CKD. EQUAL patients from Germany, Poland, Sweden and the UK were included in the present study (n = 795). Data and symptom self-report questionnaires were collected between April 2012 and September 2020. Baseline uric acid and parathyroid hormone and 10 uremic toxins were quantified. We tested the association between uremic toxins and symptoms and adjusted P-values for multiple testing.

Results

Symptoms were more frequent in women than in men with stage 4/5 CKD, while levels of various uremic toxins were higher in men. Only trimethylamine N-oxide (TMAO; positive association with fatigue), p-cresyl sulfate (PCS) with constipation and 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (negative association with shortness of breath) demonstrated moderately strong associations with symptoms in adjusted analyses. The association of phenylacetylglutamine with shortness of breath was consistent in both sexes, although it only reached statistical significance in the full population. In contrast, TMAO (fatigue) and PCS and phenylacetylglutamine (constipation) were only associated with symptoms in men, who presented higher serum levels than women.

Conclusion

Only a limited number of toxins were associated with symptoms in persons with stage 4/5 CKD. Other uremic toxins, uremia-related factors or psychosocial factors not yet explored might contribute to symptom burden.

Effect of cryopreservation on DNA damage and DNA repair activity in human blood samples in the comet assay

The comet assay is a commonly used method to determine DNA damage and repair activity in many types of samples. In recent years, the use of the comet assay in human biomonitoring became highly attractive due to its various modified versions, which may be useful to determine individual susceptibility in blood samples. However, in human biomonitoring studies, working with large sample numbers that are acquired over an extended time period requires some additional considerations. One of the most important issues is the storage of samples and its effect on the outcome of the comet assay. Another important question is the suitability of different blood preparations. In this study, we analysed the effect of cryopreservation on DNA damage and repair activity in human blood samples. In addition, we investigated the suitability of different blood preparations. The alkaline and FPG as well as two different types of repair comet assay and an in vitro hydrogen peroxide challenge were applied. Our results confirmed that cryopreserved blood preparations are suitable for investigating DNA damage in the alkaline and FPG comet assay in whole blood, buffy coat and PBMCs. Ex vivo hydrogen peroxide challenge yielded its optimal effect in isolated PBMCs. The utilised repair comet assay with either UVC or hydrogen peroxide-induced lesions and an aphidicolin block worked well in fresh PBMCs. Cryopreserved PBMCs could not be used immediately after thawing. However, a 16-h recovery with or without mitotic stimulation enabled the application of the repair comet assay, albeit only in a surviving cell fraction.

Does Cadmium Contribute to the Development of Renal Parenchymal Hypertension?

In our study we investigated 36 out-patients with renal disease, 22 of whom were hypertensive. In all patients proteinuria was present (4.30 ± 5.05 g protein/day) and kidney diseases were verified by renal biopsy. Blood cadmium in non-smokers was significantly (p< 0.05) lower than in smokers. We found a positive correlation between cadmium-concentration of blood and urine (p<0.01, R = 0.44) and between cadmium-concentration of blood and blood uric acid (p< 0.01, R = 0.44). Proteinuria was weakly correlated with cadmium concentration of urine (p<0.05, R = 0.35). Patients with renal hypertension showed a significantly higher (p< 0.05) urine cadmium excretion per day (1.60 ± 1.12 μg/day) compared to normotensives with a disease of the kidney (1.14 ± 1.47 μg/day). Our results indicate that cadmium may be involved in the development of hypertension in patients with renal disease.

Efficacy and safety of whole body vibration in maintenance hemodialysis patients - A pilot study

OBJECTIVES

The aim of this study was to assess safety and effectiveness of Whole Body Vibration exercise (WBV) to improve physical performance and parameters of inflammation in patients on maintenance hemodialysis (MHD).

METHODS

Prospective, open-label trial in n=14 patients on maintenance hemodialysis. Participants performed WBV twice weekly for 12 weeks before (n=8) or after (n=6) hemodialysis sessions. The primary endpoint was physical performance assessed by the Short-Physical-Performance-Battery (SPPB). Secondary endpoints included established parameters of musculoskeletal assessment and blood chemistry.

RESULTS

As compared to baseline, physical performance (SPPB) improved significantly (p=0.035). Moderate advances were also seen for 6-Minute-Walking test, Timed-up-and-go test, jumping height and handgrip strength. Improvements were particularly pronounced in subjects with seriously impaired baseline performance. Skeletal muscle index showed a tendency to better values. Laboratory data exhibited a significant reduction of white blood cell count and a trend to lower levels of hsCRP. WBV was generally well tolerated. Two events of clinically significant blood pressure decline occurred in patients exercising after dialysis sessions.

CONCLUSIONS

Results of this pilot study suggest effectiveness and safety of WBV in hemodialysis patients. Beneficial effects may affect both, parameters of physical performance and systemic inflammatory activity, which should be verified in larger scale clinical trials.

25-hydroxyvitamin d and advanced glycation endproducts in healthy and hypertensive subjects: are there interactions?

Advanced glycation endproducts (AGEs) accumulate during aging. Skin is the single organ of vitamin D synthesis, induced by ultraviolet B light. Accumulation of AGEs in the skin could interfere with synthesis of the vitamin, whereas the microinflammation and oxidative stress (associated with hypovitaminosis D) could amplify both the toxic effects of AGEs and their production. Clinical data on potential interactions between vitamin D3 deficiency and AGE accumulation are sparse. Here we investigated potential associations between levels of circulating vitamin D3 and those of AGEs in blood and skin with regard to markers of inflammation and oxidative stress in nondiabetic subjects. In a cross-sectional study, 146 subjects (119 healthy persons and 27 hypertensive patients; 73 male and 73 female; mean age, 57.0 ± 15.5 years) were included. Skin autofluorescence (SAF) and plasma levels of vitamin D3, AGE-associated fluorescence, high-sensitivity C-reactive protein level, and advanced oxidation protein products as well as renal function (estimated glomerular filtration rate) were determined. In a subgroup of 61 patients, N(ε)-carboxymethyllysine, soluble receptor of AGEs, and soluble vascular adhesion protein-1 were additionally analyzed. Vitamin D3 level averaged 22.5 ± 8.9 ng/mL. Prevalence of vitamin D insufficiency (20-29 ng/mL) was 43%, and that of deficiency (<20 ng/mL) 37%. The age-dependent rise in SAF was steeper in smokers and in subjects presenting arterial hypertension. No association between SAF and hypovitaminosis D was revealed. Among smokers, an inverse relationship manifested between vitamin D3 and plasma AGE-associated fluorescence as well as soluble vascular adhesion protein-1. Our data suggest that in nondiabetic adults, hypovitaminosis D does not enhance toxicity and accumulation of AGEs. Only in smokers interactions are conceivable.

Neuronal activation in the central nervous system of rats in the initial stage of chronic kidney disease-modulatory effects of losartan and moxonidine

The effect of mild chronic renal failure (CRF) induced by 4/6-nephrectomy (4/6NX) on central neuronal activations was investigated by c-Fos immunohistochemistry staining and compared to sham-operated rats. In the 4/6 NX rats also the effect of the angiotensin receptor blocker, losartan, and the central sympatholyticum moxonidine was studied for two months. In serial brain sections Fos-immunoreactive neurons were localized and classified semiquantitatively. In 37 brain areas/nuclei several neurons with different functional properties were strongly affected in 4/6NX. It elicited a moderate to high Fos-activity in areas responsible for the monoaminergic innervation of the cerebral cortex, the limbic system, the thalamus and hypothalamus (e.g. noradrenergic neurons of the locus coeruleus, serotonergic neurons in dorsal raphe, histaminergic neurons in the tuberomamillary nucleus). Other monoaminergic cell groups (A5 noradrenaline, C1 adrenaline, medullary raphe serotonin neurons) and neurons in the hypothalamic paraventricular nucleus (innervating the sympathetic preganglionic neurons and affecting the peripheral sympathetic outflow) did not show Fos-activity. Stress- and pain-sensitive cortical/subcortical areas, neurons in the limbic system, the hypothalamus and the circumventricular organs were also affected by 4/6NX. Administration of losartan and more strongly moxonidine modulated most effects and particularly inhibited Fos-activity in locus coeruleus neurons. In conclusion, 4/6NX elicits high activity in central sympathetic, stress- and pain-related brain areas as well as in the limbic system, which can be ameliorated by losartan and particularly by moxonidine. These changes indicate a high sensitivity of CNS in initial stages of CKD which could be causative in clinical disturbances.

High-tone external muscle stimulation in endstage renal disease: effects on quality of life in patients with peripheral neuropathy

OBJECTIVE

High-tone external muscle stimulation (HTEMS) has been shown to ameliorate painful peripheral neuropathy of dialysis patients. We hypothesized that HTEMS could also lead to improved parameters of health-related quality of life (HRQOL).

METHODS

25 end-stage renal disease (ESRD) patients (17 men/8 women, mean age 62.2 ± 14.2 years) were enrolled for the study. For evaluation of HRQOL the short form SF-36 was used. In addition, the Hospital Anxiety and Depression Scale (HADS) and the pain severity score were investigated. HTEMS was applied intradialytically for 1 hour, 3 times a week. Its effect was evaluated just before the beginning and both 6 and 12 weeks after onset of this study.

RESULTS

SF-36 showed a significant effect of time for the subscales of physical role functioning and social functioning. A marginal significant positive trend could be observed for physical functioning. The pain symptom questionnaire sum scores improved significantly after 12 weeks. The HADS did not change significantly.

CONCLUSION

The data indicate that intradialytic HTEMS treatment of ESRD patients with peripheral neuropathy ameliorates various components of physical health.

Neuromuscular electrostimulation techniques: historical aspects and current possibilities in treatment of pain and muscle waisting

Application of electricity for pain treatment dates back to thousands of years BC. The Ancient Egyptians and later the Greeks and Romans recognized that electrical fishes are capable of generating electric shocks for relief of pain. In the 18th and 19th centuries these natural producers of electricity were replaced by man-made electrical devices. This happened in following phases. The first was the application of static electrical currents (called Franklinism), which was produced by a friction generator. Christian Kratzenstein was the first to apply it medically, followed shortly by Benjamin Franklin. The second phase was Galvanism. This method applied a direct electrical current to the skin by chemical means, applied a direct and pulsed electrical current to the skin. In the third phase the electrical current was induced intermittently and in alternate directions (called Faradism). The fourth stage was the use of high frequency currents (called d'Arsonvalisation). The 19th century was the "golden age" of electrotherapy. It was used for countless dental, neurological, psychiatric and gynecological disturbances. However, at beginning of the 20th century electrotherapy fell from grace. It was dismissed as lacking a scientific basis and being used also by quacks and charlatans for unserious aims. Furthermore, the development of effective analgesic drugs decreased the interest in electricity. In the second half of the 20th century electrotherapy underwent a revival. Based on animal experiments and clinical investigations, its neurophysiological mechanisms were elucidated in more details. The pain relieving action of electricity was explained in particular by two main mechanisms: first, segmental inhibition of pain signals to the brain in the dorsal horn of the spinal cord and second, activation of the descending inhibitory pathway with enhanced release of endogenous opioids and other neurochemical compounds (serotonin, noradrenaline, gamma aminobutyric acid (GABA), acetylcholine and adenosine). The modern electrotherapy of neuromusculo- skeletal pain is based in particular on the following types: transcutaneous electrical nerve stimulation (TENS), percutaneous electrical nerve stimulation (PENS or electro-acupuncture) and spinal cord stimulation (SCS). In mild to moderate pain, TENS and PENS are effective methods, whereas SCS is very useful for therapy of refractory neuropathic or ischemic pain. In 2005, high tone external muscle stimulation (HTEMS) was introduced. In diabetic peripheral neuropathy, its analgesic action was more pronounced than TENS application. HTEMS appeared also to have value in the therapy of symptomatic peripheral neuropathy in end-stage renal disease (ESRD). Besides its pain-relieving effect, electrical stimulation is of major importance for prevention or treatment of muscle dysfunction and sarcopenia. In controlled clinical studies electrical myostimulation (EMS) has been shown to be effective against the sarcopenia of patients with chronic congestive heart disease, diabetes, chronic obstructive pulmonary disease and ESRD.

AT1 receptor antagonist candesartan attenuates genomic damage in peripheral blood lymphocytes of patients on maintenance hemodialysis treatment

BACKGROUND

Angiotensin II (ANG II) and advanced glycation end products (AGEs) exert genotoxic effects in vitro which were prevented by the ANG II type 1 (AT1) receptor blocker, candesartan. In end-stage renal disease (ESRD) the incidence of genomic damage is increased. A stimulation of the renin-angiotensin system and accumulation of AGEs could be involved.

METHODS

We tested whether oral co-administration of candesartan modulates enhanced DNA damage in ESRD patients. Fifteen maintenance hemodialysis (MHD) patients with mild hypertension were treated with candesartan for 4.5 months. Fourteen MHD patients served as conventionally treated uremic controls. DNA damage was measured as micronucleus frequency (MNF) in peripheral blood lymphocytes and evaluated three times before candesartan therapy and afterwards every 6 weeks.

RESULTS

Compared to 14 healthy controls, MNF at baseline was significantly elevated in MHD patients. While in the conventionally treated MHD patients the enhanced DNA damage persisted, the co-administration of candesartan ameliorated the genomic damage significantly and independently of blood pressure changes.

CONCLUSION

Blockade of AT1 receptors with candesartan can reduce DNA damage in MHD patients. Long-term studies in larger patient groups are needed to investigate whether the improved genomic damage lowers atherosclerotic complications and cancer development.

Beginning of modern concept of inflammation: the work of Friedrich Daniel von Recklinghausen and Julius Friedrich Cohnheim

In Rudolf Virchow's concept of inflammation, the basic alterations were derived from connective tissue cells, which underwent a marked metamorphosis. This cell-based and static conception was fundamentally broadened and, in part, refuted in the ensuing decade by 2 of his scholars. Friedrich Daniel von Recklinghausen characterized the pus cells in acute inflammation and made the seminal observation of their contractility and mobility. He was the first who described the wandering leukocytes which were demonstrated in particular in experimental keratitis. He also showed that pus cells could migrate from the places of their origin in the interstitium to other tissues and epithelial cells. Von Recklinghausen in addition contributed to the concept of phagocytosis. The work of Julius Friedrich Cohnheim was focused on the mechanisms involved in the extravasation of leukocytes from the blood vessels in the inflamed mesentery of the frog and carefully described the time-dependent alterations: dilatation of the arteries and veins, adhesion of colorless cells to the endothelial cells, and the subsequent transmigration from the capillaries and venules into the interstitial space. In the last few decades, experimental and clinical studies using modern techniques have fully confirmed and extended these basic observations made by von Recklinghausen and Cohnheim more than 100 years ago.

Mass-screening for early detection of renal disease: benefits and limitations of self-testing for proteinuria

INTRODUCTION

Chronic kidney diseases are of growing importance for our health system. With regard to the high number of undetected cases, screening programs provide opportunities for an early to detect and treat patients.

METHODS

With the support of local newspapers, we performed a mass screening of the citizens of Würzburg, Germany. One hundred thousand dipsticks for proteinuria were distributed. Citizens were invited to self-test their urine and to report the results to the organizing centre.

RESULTS

We received information for approximately 22% of the distributed dipsticks. Positive tests results numbered 2,458 after removal of 309 positive results for pre-diagnosed renal diseases. From family doctors, we obtained data for control investigations of 856 dipstick-positive subjects. In 104 of them, chronic proteinuria could be confirmed, due to essential hypertension (n=47), pyelo/interstitial nephritis (n=26), diabetic nephropathy (n=20), glomerulonephritis (n=4), nephrolithiasis (n=4), hypernephroma (n=2) and polycystic kidney disease (n=1).

DISCUSSION

The benefit of self-testing was an unexpectedly high compliance, even in males. However, a great number of abnormal tests could not be confirmed by family doctors, possibly owing to the time variation in urine testing (early-morning urine in the self-test vs. daytime testing by the physician), the high variability of urinary protein excretion and a large number of false-positive tests in the inexperienced participants.

CONCLUSION

Mass screening for proteinuria with self-testing enhances the awareness of renal diseases and improves the chances for an early diagnosis and therapy. Limitations are the frequent overdiagnosis of proteinuria due to minimal colour changes in the dipsticks.

Acute phase reaction to gadolinium-DTPA in dialysis patients

BACKGROUND

Several late sequelae of the administration of gadolinium (Gd)-containing MRI contrast agents have been described in patients with advanced renal failure. In an observational series, we found a remarkable frequency of peracute reactions after administration of Gd-DTPA used for cardiovascular evaluation before renal transplantation.

METHODS

In a 26-month observational period, 13 of 136 haemodialyzed or CAPD patients exhibited onset of fever, chills and nausea within hours after administration of Gd-DTPA peracute. A minority showed persistent cessation of residual diuresis. We performed blood cultures in most patients and evaluated white blood cell (WBC) counts, eosinophils, CRP, heart rate and blood pressure.

RESULTS

Within an average of 12 h (range 12-36 h) after Gd administration, the 13 patients (9 males, 4 females; median age 61 years, range 47-79) developed consistent symptomatology with fever (median 39.0 degrees C, range 37.5-39.5), chills, malaise, hypotension, vomiting, dyspnoea-initially raising suspicion of septicaemia. Subsequent blood cultures on bacterial contamination of the injected product remained negative throughout; bacterial or endotoxin contamination of the reagent was excluded. Steroids were tried in the first two patients without a noticeable effect. In all subsequent patients, symptoms were attenuated during the first 5 h dialysis (F60HPS with 280 ml/min blood flow) and disappeared within 72 h. CRP levels remained markedly elevated up to 14 days. Lymphopenia was seen in all patients, and polymorphic neutrophils (PMN) remained normal. Two polyuric patients developed persistent anuria. After a median of 16 months, none of these patients developed nephrogenic systemic fibrosis.

CONCLUSION

This series with unusually severe acute phase reactions was caused by one specific preparation. Such peracute reactions may be relevant for the so-far largely unresolved pathogenesis of the skin reaction to some Gd products in end-stage renal disease (ESRD) patients. It remains unresolved whether the reaction observed with Gd-DTPA do in principle also occur with other Gd reagents.

Use of cinacalcet HCl to achieve the recommended targets of bone metabolism in a patient with therapy-resistant renal hyperparathyroidism

We report on a patient with end-stage renal disease and severe progressive secondary hyperparathyroidism, whose condition failed to respond to conventional pharmacologic or surgical interventions. Although immunotherapy produced a partial response, it failed to decrease serum parathyroid hormone to the levels recommended by the National Kidney Foundation Kidney Disease Outcomes Quality Initiative clinical practice guidelines. Treatment with a new calcimimetic agent, cinacalcet HCl (Mimpara, Amgen, Munich, Germany), resulted in a rapid decline in elevated parathyroid hormone levels, near normalization of other laboratory markers of bone metabolism, improvement in mobility and skeletal pain caused by renal osteodystrophy, and an increase in body weight.

Benfotiamine reduces genomic damage in peripheral lymphocytes of hemodialysis patients

Hemodialysis patients have an elevated genomic damage in peripheral blood lymphocytes (PBLs) and an increased cancer incidence, possibly due to accumulation of uremic toxins like advanced glycation end products (AGEs). Because the vitamin B1 prodrug benfotiamine reduces AGE levels in experimental diabetes, and dialysis patients often suffer from vitamin B1 deficiency, we conducted two consecutive studies supplementing hemodialysis patients with benfotiamine. In both studies, genomic damage was measured as micronucleus frequency of PBLs before and at three time-points after initiation of benfotiamine supplementation. AGE-associated fluorescence in plasma, and in the second study additionally, the antioxidative capacity of plasma was analyzed. Benfotiamine significantly lowered the genomic damage of PBLs in hemodialysis patients of both studies independent of changes in plasma AGE levels. The second study gave a hint to the mechanism, as the antioxidative capacity of the plasma of the treated patients clearly increased, which might ameliorate the DNA damage.

High-tone external muscle stimulation in end-stage renal disease: effects on symptomatic diabetic and uremic peripheral neuropathy

OBJECTIVE AND DESIGN

Pain and peripheral neuropathy are frequent complications of end-stage renal disease (ESRD). Because drug treatment is associated with numerous side effects and is largely ineffective in many maintenance hemodialysis (MHD) patients, nonpharmacologic strategies such as electrotherapy are a potential recourse. Among various forms of electrostimulation, high-tone external muscle stimulation (HTEMS) is a promising alternative treatment for symptomatic diabetic peripheral polyneuropathy (PPN), as demonstrated in a short-term study. Based on these novel findings, we performed a prospective, nonrandomized, pilot trial in MHD patients to determine (1) whether HTEMS is also effective in treating diabetic PPN in the uremic state, and (2) whether uremic PPN is similarly modulated.

PATIENTS AND INTERVENTIONS

In total, 40 MHD patients diagnosed with symptomatic PPN (25 with diabetic and 15 with uremic PPN) were enrolled. Both lower extremities were treated intradialytically with HTEMS for 1 hour, three times a week. Initially, a subgroup of 12 patients was followed for 4 weeks, and a further 28 patients for 12 weeks. The patients' degree of neuropathy was graded at baseline before HTEMS and after 1 and 3 months, respectively. Five neuropathic symptoms (tingling, burning, pain, numbness, and numbness in painful areas) as well as sleep disturbances were measured, using the 10-point Neuropathic Pain Scale of Galer and Jensen (Neurology 48:332-338, 1997). A positive response was defined as the improvement of one symptom or more, by at least 3 points. Other parameters included blood pressure, heart rate, dry body weight, and a routine laboratory investigation.

RESULTS

The HTEMS led to a significant improvement in all five neuropathic symptoms, and to a significant reduction in sleep disturbances for both diabetic and uremic PPN. The response was independent of the patient's age, with a responder rate of 73%. The improvement of neuropathy was time-dependent, with the best results achieved after 3 months of treatment. The HTEMS was well-tolerated by nearly all patients.

CONCLUSIONS

This pilot study shows for the first time that HTEMS can ameliorate the discomfort and pain associated with both diabetic and uremic PPN in MHD patients, and could be a valuable supplement in the treatment of pain and neuropathic discomfort in patients who do not respond to, or are unable to participate in, exercise programs during hemodialysis treatment.

Cinacalcet HCl (Sensipar/ Mimpara) is an effective chronic therapy for hemodialysis patients with secondary hyperparathyroidism

AIMS

This 1-year double-blind, placebo-controlled, multicenter study evaluated the long-term safety and efficacy of cinacalcet for the treatment of secondary hyperparathyroidism in patients receiving hemodialysis.

METHOD

Patients were randomly assigned in a 1:1 ratio to cinacalcet or control treatment groups. The initial dose of cinacalcet (or matching placebo) was 30 mg. Doses were titrated every 3 or 4 weeks based on the intact parathyroid hormone (iPTH) response and safety profile. Sequential doses included 30, 60, 90, 120 and 180 mg/d. Phosphate binders and vitamin D sterols were adjusted per protocol as needed to control levels of calcium and phosphorus. Efficacy and safety were compared between treatment groups among patients who completed the study (52 total weeks of treatment). Reasons for withdrawal are presented for patients who did not complete the study.

RESULTS

A total of 210 patients completed 52 weeks of double-blinded treatment with cinacalcet (n = 99) or placebo (n = 111). Over the last 6 months of the study, a greater proportion of patients in the cinacalcet group than the control group achieved an iPTH level < or = 250 pg/ml (61.6 vs. 9.9%, p < 0.001) or a > or = 30% decrease in iPTH from baseline (81.8 vs. 21.6%, p < 0.001). Mean iPTH levels decreased by -47.8% in the cinacalcet group and increased by +12.9% in the control group. Mean percentage changes in other laboratory values in the cinacalcet and control groups included the following: serum calcium -6.5 vs. +0.9% (p < 0.001), serum phosphorus -3.6 vs. -1.1% (p = 0.465), and Ca x P -9.9 vs. -0.3% (p = 0.006). The most commonly reported adverse events related to study drug by the investigators included nausea (13% cinacalcet, 5% control), investigator-reported hypocalcemia (11% cinacalcet, 1% control), vomiting (9% cinacalcet, 2% control), dyspepsia (5% cinacalcet, 4% control), and diarrhea (5% cinacalcet, 2% control).

CONCLUSIONS

Treatment with cinacalcet is a safe and effective therapy for long-term control of secondary hyperparathyroidism. 1-year therapy with cinacalcet was associated with sustained, clinically significant reductions in calcium, Ca x P and iPTH which allowed a greater percentage of patients to achieve NKF-KDOQI target goals for PTH and Ca x P.

Central atrial natriuretic peptide in dehydration

To test the effect of dehydration on brain atrial natriuretic peptide (ANP) concentrations in areas important to salt appetite, water balance and cardiovascular regulation, we subjected rats to dehydration and rehydration and measured ANP concentration in 18 brain areas, as well as all relevant peripheral parameters. Water deprivation decreased body weight, blood pressure, urine volume, and plasma ANP, while it increased urine and plasma osmolality, angiotensin II, and vasopressin. ANP greatly increased in 17 and 18 brain areas (all cut cerebral cortex) by 24 h. Rehydration for 12 h corrected all changes evoked by dehydration, including elevated ANP levels in brain. We conclude that chronic dehydration results in increased ANP in brain areas important to salt appetite and water balance. These results support a role for ANP as a neuroregulatory substance that participates in salt and water balance.

Renal disease in obesity: the need for greater attention

Excess body weight may be associated with various functional/structural lesions of the kidney. The spectrum ranges from glomerulomegaly with or without focal or segmental glomerulosclerosis, to diabetic nephropathy, to carcinoma of the kidney and nephrolithiasis. The first sign of renal injury is microalbuminuria or frank proteinuria, in particular in the presence of hypertension. The occurrence of microalbuminuria and/or chronic kidney insufficiency (glomerular filtration rate < 60 mL/min/1.73 m2) is related to the increasing number of components of the metabolic syndrome, ie, central obesity, elevated fasting blood glucose level, hypertriglycerides, low high-density lipoprotein cholesterol, and hypertension. In the long run, end-stage renal failure may develop. An increased body mass index is particularly harmful in patients with reduced renal functional mass (unilateral renal agenesis or nephrectomy) and other renal diseases (immunoglobulin A nephritis and chronic graft dysfunction after kidney transplantation). In the pathogenesis of obesity-associated glomerulopathy, hyperfiltration is of fundamental importance. The factors involved are energy intake (high protein and salt), hyperinsulinemia, and enhanced tubuloglomerular feedback because of increased sodium reabsorption. The adrenergic and renin-angiotensin-aldosterone systems as well as glucocorticoids are stimulated. In addition, several active proteins generated in the central adipose tissue, such as leptin, proinflammatory cytokines, plasminogen activator inhibitor-1, angiotensinogen, and growth factors (transforming growth factor-beta1), as well as low levels of the protective adiponectin, may contribute to renal injury. Of greatest importance is the development of hypertension and of diabetes, which are directly related to the severity of central obesity. Obesity-associated renal disease should be prevented or retarded by weight reduction following lifestyle modification (salt restriction, hypocaloric diet, aerobic exercise), or eventually by antiobesity medication or bariatric surgery. In the presence of glomerulopathy and/or hypertension, angiotensin converting enzyme inhibitors or angiotensin II type I receptor blockers are the drugs of choice to improve glomerular hyperfiltration.

Using GI-specific patient outcome measures in renal transplant patients: Validation of the GSRS and GIQLI

INTRODUCTION

Gastrointestinal (GI) side-effects occur frequently as a result of immunosuppressant regimens used in renal transplant patients. Little effort has been made to quantify the impact of these side-effects on patients' health-related quality of life and symptom severity.

OBJECTIVE

To assess the psychometric characteristics of two GI-specific outcome instruments (the Gastrointestinal Rating Scale (GSRS) and the Gastrointestinal Quality of Life Index (GIQLI)) for use in post-renal transplant patients.

METHODS

Cross-sectional study conducted at 5 clinical centers in 4 countries. Patients were required to be on mycophenolate mofetil and a calcineurin inhibitor. Patients completed the GSRS, GIQLI and two generic instruments (the Psychological General Well-Being Index and the EQ-5D) at one timepoint. Reliability, construct and known groups validity were assessed.

RESULTS

In general the GSRS and the GIQLI demonstrated Cronbach's alphas higher than 0.70. The GIQLI was moderately to highly correlated with the PGWB and EQ-5D. Correlations among the GSRS and generic instruments were slightly lower. The GSRS and GIQLI both distinguished between patients with and without GI complaints (all p<0.05).

CONCLUSIONS

The GSRS and the GIQLI are appropriate for use in a post-renal transplant population. Scores on both instruments demonstrated significant differences between renal transplant patients with GI complications and without GI complications.

Relation between Different Treatment Modalities and Genomic Damage of End-Stage Renal Failure Patients

BACKGROUND

Patients with end-stage renal disease display enhanced genomic damage. We investigated the relation between genomic damage and different treatment modalities.

METHODS

In a longitudinal study two groups of patients were analyzed in monthly intervals. We assessed the initiation of hemodialysis in 5 conservatively treated patients, and a switch from hemodialysis to hemodiafiltration in 7 patients. DNA damage was investigated in peripheral blood lymphocytes by micronucleus frequency and by comet assay analysis. With regard to potential genotoxicity of advanced glycation end products (AGEs), levels of imidazolone A and AGE-associated fluorescence (AGE-FL) were determined.

RESULTS

The initiation of hemodialysis did not alter the genomic damage. In patients who switched from hemodialysis to hemodiafiltration, a small but significant reduction in the comet assay but not in the micronucleus frequency was observed. Elevated plasma levels of imidazolone A and AGE-FL were not influenced by the treatment modalities.

CONCLUSION

In our small patient group no major reduction of the elevated genomic damage could be reached. Disease factors not influenced by altered dialysis modalities may have contributed considerably in our patient group. The persisting high levels of DNA damage suggest a need for further improvement. Inhibiting AGE formation may be one promising way for the future.

The contribution of Rudolf Virchow to the concept of inflammation: what is still of importance?

At the beginning of the 19th century, medicine was based largely on speculative and philosophical concepts. The greatest merit of Rudolf Virchow was without doubt a way of thinking based on natural science. In place of the empirical chaos represented by the doctrines of humors and crasis, he created the new paradigm of cellular pathology. In the field of inflammation, he critically analyzed the meaning of the four key symptoms of inflammation (redness, swelling, heat and pain) and postulated that inflammation cannot be represented as a single process but rather constitutes various inflammatory processes. In addition he introduced the functio laesa , denoting the restricted function of inflamed tissues. In the pathogenesis of inflammation, Virchow highlighted the importance of the inflammatory stimulus. The irritatio is the starting point and the conditio sine qua non . Through his pathohistological investigations in experimental animals and in humans, inflammation was widely accepted as the central cause of atherosclerosis, until the end of the 19th century, and has been confirmed in recent decades. It was Virchow who first coined the term endarteriitis deformans . Likewise, he was also the first to hypothesize a link between microinflammation and subsequent cancer development. This hypothesis has recently been corroborated by numerous studies and may have therapeutic consequences. Virchow contributed to nearly all aspects of human pathology and championed the cause of social medicine.

Effect of Different Hemodialysis Regimens on Genomic Damage in End-Stage Renal Failure

Patients with end-stage renal disease display enhanced genomic damage that may have pathophysiologic relevance for cancer development and cardiovascular complications. We investigated to what extent the genomic damage in peripheral blood lymphocytes can be modulated #1: by initiation of standard hemodialysis (SHD) in formerly conservatively treated end-stage renal disease patients, #2: by a switch from SHD to hemodiafiltration, and #3: daily dialysis (DHD). Genomic damage was evaluated by the micronuclei (MN) frequency test and the comet assay (CA). In a prospective study we found that initiation of SHD did not induce significant changes of genomic damage in peripheral blood lymphocytes whereas the change to hemodiafiltration improved the percentage of DNA in the tail as measured by CA without modulating the MN frequency. In a cross-sectional investigation the degree of genomic damage as evaluated by MN frequency was significantly lower in a patient group treated by DHD as compared with a group treated by SHD. In the DHD patients there also was a significant decrease of the plasma concentrations of urea and the advanced glycation end products imidazolone A, carboxymethyllysine, and of advanced glycation end product-associated fluorescence.

Genomic damage in end-stage renal failure: potential involvement of advanced glycation end products and carbonyl stress

In patients with chronic renal failure, genomic damage has been shown by numerous biomarkers, such as micronuclei frequency and comet assay (single-cell gel electrophoresis) in peripheral lymphocytes, 8-hydroxy 2'-deoxyguanosine (8-OH-dG) content in leukocytes, mitochondrial DNA deletions in skeletal muscle tissue and hair follicles, as well as in DNA repair mechanisms in freshly isolated lymphocytes after ultraviolet light exposure. In the pathogenesis of DNA damage--besides genetic influences, enhanced reactive oxygen species (ROS), and lipid peroxidation-the genotoxic potential of advanced glycation end products (AGEs) and reactive carbonyl compounds deserve special attention. In fact, reactions of glucose with DNA can lead to mutagenic DNA AGEs. In vitro, incubation of tubulus cells with various AGEs and methylglyoxal induces DNA damage, which is suppressed by antioxidants. This underlines the role played by oxidative stress in DNA damage.

Gastointestinal-Specific Patient-Reported Outcome Instruments Differentiate Between Renal Transplant Patients With or Without GI Complications

BACKGROUND

Gastrointestinal (GI) complications are frequently reported postrenal transplant and are often associated with immunosuppressant regimens including mycophenolate mofetil (MMF). This study evaluated the ability of two GI-specific patient-reported outcome (PRO) instruments to differentiate between patients with and without GI complaints.

METHODS

Discriminant validity of the Gastrointestinal Symptom Rating Scale (GSRS) and Gastrointestinal Quality of Life Index (GIQLI), as well as two generic instruments (Psychological General Well-Being Index (PGWB) and EQ-5D, was assessed in a multinational study of renal transplant recipients. Patients received therapy that included a calcineurin inhibitor and MMF. Both t-tests and ANOVAs were used to examine differences between patients with and without GI complaints, among levels of severity, and between patients reporting presence/absence of specific GI side effects.

RESULTS

Of 96 patients recruited (56% male), 43% had none, 39% mild, 13% moderate, and 6% severe GI symptoms. All GSRS subscales and the GIQLI total and four of the five subscale scores significantly differentiated between patients with/without GI complications (P < .05). The PGWB total score and three subscales, the EQ-5D significantly differentiated between the two groups (P < .05). Only GI-specific instruments discriminated between some severity levels; for example, the GSRS abdominal pain subscale discriminated between patients at all levels of severity (P < .05). The GIQLI total score and symptoms subscale differentiated between patients with no symptoms and those with mild or moderate or severe symptoms (P < .05).

CONCLUSIONS

The GSRS and GIQLI differentiated between patients with/without GI side effects and by symptom severity better than did generic instruments, demonstrating excellent discriminant ability in this population.

Effect of dialysis flux and membrane material on dyslipidaemia and inflammation in haemodialysis patients

BACKGROUND

Dyslipidaemia, inflammation and oxidative stress are prominent risk factors that potentially cause vascular disease in haemodialysis patients. Dialysis modalities affect uraemic dyslipidaemia, possibly by modifying oxidative stress, but the effects of dialyser flux and membrane material on atherogenic remnant particles and oxidized low-density lipoproteins (LDL) are unknown.

METHODS

We performed a randomized crossover study in 36 patients on haemodialysis to analyse the effect of dialyser flux and membrane material on plasma lipids, apolipoproteins and markers of inflammation and oxidative stress. Stable patients on low-flux dialysis with polysulphone for >/=6 weeks were assigned to high-flux polysulphone or high-flux modified cellulose with similar dialyser surface area and permeability characteristics and crossed over twice every 6 weeks.

RESULTS

Thirty patients completed the study per protocol. Treatments with high-flux polysulphone and modified cellulose lowered serum triglyceride (by 20% and 10%, respectively; P<0.05) and remnant-like particle cholesterol by 32% (P<0.001) and 11% (NS) after the first 6 weeks of treatment. Oxidized LDL decreased significantly with high-flux polysulphone, but not with modified cellulose. Apolipoproteins CII and CIII were reduced, whereas the ratio CII/CIII was increased (all P<0.05). Acute-phase proteins and LDL and high-density lipoprotein cholesterol remained unaffected.

CONCLUSIONS

This randomized crossover study demonstrates a potent effect of high-flux haemodialysis on uraemic dyslipidaemia. Polysulphone membrane material showed superiority on oxidatively modified LDL, an indicator of oxidative stress in haemodialysis patients.

[Overweight and obesity--risk factors in the development and progression of renal disease]

Overweight/obesity represent an underestimated risk factor of renal disease. The incidence of obesity-related glomerulopathy (ORG) tremendously increased within the last decade. The first sign of renal damage in overweight conditions is microalbuminuria or proteinuria, indicating the potential risk of its progression to renal insufficiency and the development of premature cardiovascular events. In the early stage of obesity renal hemodynamics are characterized by a renal hypercirculation and glomerular hyperfiltration, particularly in the presence of hypertension. The hyperfiltration is especially harmful in patients with pre-existing inflammatory and metabolic renal disease, or under the conditions of reduced renal mass. Histopathologically, ORG is characterized by glomerulomegaly with/without signs of focal segmental glomerulosclerosis. Pathogenetically, numerous factors are involved, e.g. enhanced glomerular capillary pressure, adrenergic nerve overactivity, inappropriate activation of the renin-angiotensin-aldosterone system, insulin resistance, hyperinsulinemia and hyperleptinemia, dyslipidemia, enhanced clotting tendency and sodium retention. Diabetic nephropathy is one of the most serious complications of obesity-induced diabetes. In the industrial nations type 2 diabetes is the single most frequent cause of end-stage renal disease. After kidney transplantation, overweight/obesity is associated with a less favourable prognosis for the survival of the graft and the patient. Incidence of renal cell carcinomas is enhanced in overweight/obesity. Obesity-related renal disease may be prevented/postponed by an early weight reduction, by dietary intervention combined with physical exercise. In the advanced stages of renal disease benefits of weight reduction are minimal. Concomitant administration of angiotensin-converting-enzyme inhibitors or angiotensin II receptor 1 blockers exerts antiproteinuric effects and thereby aid in retarding the disease progression. Aimed prevention and treatment of obesity represent a challenge for the healthcare system. The concerted action of physicians, patients and the public health authorities is needed.

Georg Ganter--a pioneer of peritoneal dialysis and his tragic academic demise at the hand of the Nazi regime

First reports in German literature on the effective removal of uremic toxins by means of extracorporeal hemodialysis in bi-nephrectomized, acute uremic dogs were given by Heinrich Necheles and Georg Haas. These methods were viewed with great scepticism by Georg Ganter who criticized in particular the extensive operative procedure by use of the femoral artery and vein, the size and fragility of the dialysers, as well as the potential toxic effects of the anticoagulant hirudin. As an alternative approach, he suggested the use of the peritoneum as an especially large endogenous dialysis membrane. In 1923, in experiments on ureter-ligated guinea pigs and rabbits, he demonstrated that the single or repeated instillation (after effective draining) of physiological NaCl solution improves both the symptoms of uremia and the blood urea nitrogen level. In patients this new procedure was implemented only sporadically and in the form of a single fluid instillation after a first observation in a uremic patient where a pleura exudate was substituted: in a female patient with acute uremia as a consequence of a ureter occlusion, due to uterus carcinoma, and in a patient with a diabetic coma. In spite of these limited experiences, Ganter was convinced of the superiority of his method over the troublesome hemodialysis therapy and recommended its broader clinical application.

Glucose degradation products in PD fluids: do they disappear from the peritoneal cavity and enter the systemic circulation?

BACKGROUND

Glucose degradation products (GDP) are generated in peritoneal dialysis (PD) fluid during heat sterilization and storage. They are thought to adversely affect the peritoneal membrane. The fate of GDP within the peritoneal cavity has not been well characterized.

METHODS

A clinical study was designed to determine (1). whether during the dwell in the peritoneal cavity GDP concentration decreases in the PD fluid as assessed by ex vivo formation of AGE; (2). whether exposure to GDP-containing PD fluids increases plasma fluorescence (as an index of plasma AGE concentration) as well as plasma carboxymethyllysine (CML) concentration; and (3). whether exposure to GDP-containing PD fluids adversely affects glycoprotein CA 125 concentration. A two-group crossover design was adopted comprising two consecutive observation periods of eight weeks each. Stable PD patients were exposed in random order either to conventional PD fluid (heat sterilized at pH 5.5) and subsequently to PD test fluid (or the 2 fluids in reverse order). The PD test fluid was sterilized using a multicompartment bag system separating highly concentrated glucose at pH 3 from the buffer solution. Conventional and test fluids differed with respect to concentrations of GDP, that is, 3-deoxyglucosone (118 vs. 12.3 micromol/L), methylglyoxal (5.3 micromol/L vs. below detection threshold), 3, 4-dideoxyglucosone-3-ene (10 micromol/L vs. below detection threshold) and acetaldehyde (226 vs. <1 micromol/L).

RESULTS

The following results were obtained. First, methylglyoxal disappeared completely as early as two hours after intraperitoneal instillation of conventional PD fluid. Second, when spent conventional dialysate was recovered after a two hour and particularly an eight hour dwell and subsequently incubated ex vivo with 40 mg of human serum albumin, there was a continuous decrease of AGE-forming capacity, that is, less generation of fluorescence (AGE) and pyrraline (non-fluorescent Amadori product), and an increase of advanced oxidation protein products (AOPP) in the spent dialysate. Third, plasma fluorescence (exc. 350/em. 430 nm) as an index of circulating AGE compounds as well as plasma CML concentrations were significantly higher in the conventional PD fluid period versus low GDP PD fluid period. Fourth, CA 125 concentrations in spent dialysate were higher during the low GDP PD fluid period compared to the conventional PD fluid period.

CONCLUSION

Conventional PD fluid undergoes modifications during intraperitoneal dwell with a loss of AGE forming capacity, suggesting breakdown, precipitation or resorption of GDP in vivo. This is accompanied by an increase in plasma AGE compounds.

The central vasopressinergic system in experimental left ventricular hypertrophy and dysfunction

In the course of cardiac diseases, various neuruhomonal systems in the plasma are activated. So far there have been only isolated results of investigations about the functional state of central neuropeptide systems in cardiac diseases and, in particular, in heart failure. We investigated, therefore, the central vasopressinergic system, an important neuropeptide system in cardiocirculatory regulation in a model of myocardial hypertrophy and left ventricular dysfunction, a model of supravalvular aortic stenosis. In addition to increased vasopressin concentrations in plasma, central vasopressin is also altered in this model. A differential stimulation of vasopressin in the hypothalamic areas and in the areas of the brain stem that are involved in central cardiocirculatory regulation was detected. Reduced vasopressin concentrations in the locus coeruleus, an important regulatory area of sympathetic nervous activity, suggest a central regulatory mechanism through which stimulation of the sympathetic nervous activity can be prevented. Our investigations showed that non-osmotic factors like the baroreceptor reflex and angiotensin II, are important stimuli of the vasopressinergic system. We were also able to show that the central vasopressinergic system in rats with experimental heart failure and myocardial hypertrophy is inhibited by treatment with an ACE inhibitor and AT1 receptor antagonist. As seen with autoradiography, this effect is mediated by a central effect of the drugs. Research into central regulatory mechanisms in cardiovascular diseases is, on the one hand, of crucial importance to our understanding of complex pathophysiological processes, and on the other hand, it serves the development of new therapeutic approaches with the goal of influencing these mechanisms directly pharmacologically and for the elucidation of central, currently unknown effects of cardiovascular drugs.

Plasma levels of advanced glycation end products during haemodialysis, haemodiafiltration and haemofiltration: potential importance of dialysate quality

BACKGROUND

Advanced glycation end products (AGEs) accumulate in patients with end-stage renal disease (ESRD). The aim of this study was to investigate the potential influence of different modalities of renal replacement therapies on plasma AGE levels.

METHODS

The removal of AGEs by high-flux haemodialysis (HD) using standard and ultrapure dialysis fluid (SDF and UDF), by haemodiafiltration (HDF) and by haemofiltration (HF) was studied by fluorescence spectroscopy and by a carboxymethyllysine (CML)-specific ELISA. In addition, molecular weight distribution of fluorescent AGE products in serum of several patients was analysed by gel filtration.

RESULTS

The highest AGE-typical fluorescence was found in the serum of patients on HD using SDF (114,667+/-18,967 arbitrary units (AU)), followed by patients on HDF (86,912+/-24,411 AU, P<0.005), by patients on HD using UDF (74,953+/-21,152 AU, P<0.0001) and by patients on HF (74 039+/-17 027 AU, P<0.0001). Similar results were found for serum CML levels with the highest values in HD patients on SDF (1609+/-504 ng/ml), followed by patients on HF (1354+/-614 ng/ml, P<0.001), then by HD patients on UDF (1310+/-403 ng/ml, P<0.001) and by patients on HDF (1132+/-338 ng/ml, P<0.001). The removal rate of AGEs, as evaluated by the determination of the pre-/post-dialysis AGE differences, was comparable across all groups.

CONCLUSION

These findings suggest that factors other than removal are responsible for the lower pre-dialysis AGE levels found in patients on convective dialysis as well as on HD with UDF. A role of water quality is assumed. This is corroborated by the finding that the high molecular weight AGE-fraction is preferentially lowered in comparison with patients on HD with SDF, as analysed by gel filtration chromatography. These findings could be best explained by a less severe oxidative stress (i.e. resulting in decreased AGE generation) with HF and HDF, as well as with ultrapure HD.

Efficacy and safety of a 7.5% icodextrin peritoneal dialysis solution in patients treated with automated peritoneal dialysis

In a randomized, prospective, multicenter study, we compared the safety, efficacy, and metabolic effects of a 7.5% icodextrin solution (Extraneal) with a 2.27% glucose solution for long dwell exchanges in patients undergoing automated peritoneal dialysis. Thirty-nine stable patients on automated peritoneal dialysis were randomized to receive either icodextrin (n = 20) or glucose 2.27% solution (n = 19). The study included a 2-week baseline period followed by a 12-week icodextrin treatment phase and a 2-week follow-up period when switching back to glucose. The average net ultrafiltration during the long dwell period was 278 +/- 43 mL/d for the icodextrin group and -138 +/- 81 mL/d for the control group (P < 0.001). The higher ultrafiltration volume with icodextrin was associated with higher creatinine (2.59 +/- 0.09 mL/min versus 2.16 +/- 0.11 mL/min) and urea (2.67 +/- 0.09 mL/min versus 2.28 +/- 0.12 mL/min) peritoneal clearances for the long dwell (both P < 0.001). Ultrafiltration rate per mass of carbohydrate absorbed was +5.2 +/- 1.2 microL/min/g in the icodextrin group and -5.5 +/- 2.8 microL/min/g in the glucose group (P < 0.001). In the icodextrin group, there was a decrease in serum sodium and chloride compared with baseline (P < 0.01). Total dialysate sodium removal increased in the icodextrin group from 226.7 mEq to 269.6 mEq (week 12, P < 0.001). Serum alpha-amylase activity decreased from 103 U/L to 16 U/L (P < 0.001). The total icodextrin plasma levels reached a steady-state concentration of 6,187 +/- 399 mg/L after 1 week of treatment. Urine volume and residual renal function were not specifically affected by icodextrin compared with glucose. None of the laboratory changes resulted in any reported clinically meaningful side effect. Icodextrin produced increased, sustained ultrafiltration during the long dwell period, increasing (convective) peritoneal clearance and sodium removal in automated peritoneal dialysis patients.

Comet-assay analysis identifies genomic damage in lymphocytes of uremic patients

This study investigates genomic damage in peripheral lymphocytes from patients with moderate to severe chronic renal insufficiency and those on long-term maintenance hemodialysis (MHD) and hemodiafiltration therapy. As a measure for genomic damage, the comet assay (single-cell gel electrophoresis) was applied. This test detects single- and double-strand breaks and alkali labile sites through electrophoretic mobility of the resulting fragments. The average damage (percentage of DNA in the tail region of the comet) observed in cells of the control group of 21 healthy subjects was 10.5% +/- 0.8%. There was a significant increase to 14.7% +/- 3.5% in cells of 23 patients with chronic renal failure, and a further increase to 17.1% +/- 3.5% in the subgroup of 12 patients with serum creatinine values greater than 6 mg/dL. Damage was 16.7% +/- 4.2% in cells of the MHD group (26 patients) and 20.1% +/- 3.0% in the subgroup with MHD therapy longer than 10 years (8 patients). Cellular DNA damage in the group of 15 maintenance hemodiafiltration patients was 15.6% +/- 2.1%, ranging between predialysis and MHD patients, and did not seem to increase with treatment time. These results, together with previously observed elevated frequencies of micronuclei, decreased DNA repair, and increased cancer incidence described for these patient groups, emphasize the need to further optimize the current therapy for reducing the degree of genomic damage.

A randomized, controlled parallel-group trial on efficacy and safety of iron sucrose (Venofer) vs iron gluconate (Ferrlecit) in haemodialysis patients treated with rHuEpo

BACKGROUND

The objectives of the present trial were to compare the efficacy and safety of two i.v. iron preparations with respect to haemoglobin levels, iron status and recombinant human erythropoetin (rHuEpo) dosage requirements in stable, rHuEpo-treated haemodialysis patients (maintenance phase of iron treatment) over 6 months.

METHODS

A total of 59 patients were randomized and assigned to one of two treatment groups and 55 patients were analysed (iron sucrose n=27; iron gluconate n=28). Iron sucrose was administered in a dose of 250 mg iron diluted in 100 ml normal saline given over 60 min once per month, while 62.5 mg iron as iron gluconate was given once per week in a slow push injection (5 min).

RESULTS

--Efficacy parameters: Haemoglobin levels could be maintained from baseline to endpoint in both groups. There were, however, more patients in the iron sucrose group than in the iron gluconate group for whom treatment was discontinued because their haemoglobin values exceeded 12.5 g/dl or ferritin values exceeded 1000 ng/ml (five vs two and three vs one patient, respectively). Transferrin saturation and serum ferritin increased significantly in both groups (+255.7 ng/ml with iron sucrose and +278.5 ng/ml with iron gluconate), while rHuEpo dosage did not change significantly throughout the study. --Safety parameters: There were a total of 174 infusions of iron sucrose and 720 injections of iron gluconate during the trial; all of them were well tolerated. In particular, we did not observe anaphylactoid reactions or any events suggestive of iron toxicity such as hypotension, dizziness, or nausea.

CONCLUSIONS

High doses of iron sucrose (Venofer((R)) at a dose of 250 mg/month) was equally effective in maintaining haemoglobin and equally well tolerated as low doses of iron gluconate (Ferrlecit((R)) at a dose of 62.5 mg once per week) in stable, rHuEpo treated haemodialysis patients.

Chronic effects of ACE-inhibition (quinapril) and angiotensin-II-type-1 receptor blockade (losartan) on atrial natriuretic peptide in brain nuclei of rats with experimental myocardial infarction

Alterations of the central nervous system may be important for imbalance of cardiovascular and fluid regulation in heart failure. The central renin-angiotensin and atrial natriuretic peptide (ANP) systems act as mutual antagonists. The effects of angiotensin converting enzyme (ACE) inhibition (quinapril, 6 mg/kg/day) and angiotensin II type 1 (AT1) receptor blockade (losartan, 10 mg/kg/day) on ANP levels in 18 selected, microdissected brain nuclei were determined in sham-operated rats and rats with left ventricular dysfunction 8 weeks after myocardial infarction (MI). Plasma ANP tended to increase in MI rats and was further increased by quinapril. ANP was decreased in 12 brain areas of MI rats. ANP concentration was also significantly decreased by quinapril in six brain nuclei including subfornical organ and organum vasculosum laminae terminalis (areas lacking blood-brain barrier), and by losartan in 16 brain nuclei outside and within the blood-brain barrier in sham operated rats. However, both quinapril and losartan prevented a further reduction of central ANP as a result of myocardial infarction. These data suggest that there are effects on central ANP that result from chronic left ventricular dysfunction as well as an ACE-inhibitor and AT1-antagonist. Mechanisms and consequences of central ANP depression remain unclear. They could, however, support systemic vasoconstriction and sodium and fluid retention.

Central inhibition of AT1receptors by eprosartan--in vitro autoradiography in the brain

All components of the renin-angiotensin system have been demonstrated in the brain and AT1 receptors have been localized in brain areas involved in central cardiovascular regulation. It is currently unclear whether AT1 receptor antagonists, which are increasingly used in the treatment of arterial hypertension and chronic heart failure, have the potential to mediate action via the central renin-angiotensin system. Therefore, we tested the in vivo access of the non-peptide AT1 receptor antagonist, eprosartan (30 and 60 mg per kg of body weight (BW) for 4 weeks, i.p. administered by osmotic minipumps), to angiotensin II receptors in the rat brain by in vitro autoradiography with 125I- (Sar1- Ile8) angiotensin II as a ligand. Eprosartan significantly increased plasma renin activity by four-fold and six-fold at doses of 30 and 60 mg x kg(-1), respectively (P< 0.05 vs CTRL). In the brain, eprosartan produced a dose-dependent inhibition of AT receptor binding in the median cerebral artery ( 850 +/- 249 and 650 +/- 106 vs 1072 +/- 116 dpm x mm(-2) of CTRL; P< 0.05). Furthermore, eprosartan inhibited angiotensin II receptor binding in discrete brain areas, which express exclusively, or predominantly, AT1 receptors both outside and within the blood-brain barrier, such as the paraventricular nucleus ( 180 +/- 47 and 130 +/- 18 vs 545 +/- 99 dpm x mm(-2)of CTRL; P< 0.05), the subfornical organ ( 106 +/- 26 and 112 +/- 17 vs 619 +/- 256 dpm x mm(-2)of CTRL; P< 0.05), and the organum vasculosum laminae terminalis ( 461 +/- 110 and 763 +/- 136 vs 1033 +/- 123 dpmx mm(-2)of CTRL; P< 0.05). These results emphasize that eprosartan readily crosses the blood-brain barrier in vivo and selectively inhibits binding to AT1 receptors in specific brain nuclei. The modulation of central regulatory mechanisms might contribute to AT1 receptor antagonists overall therapeutic efficacy in cardiovascular disease.

Prevalence of hepatitis G in patients on chronic hemodialysis

Hepatitis G virus (HGV) is a newly described RNA virus from the family of flaviviridae. It is closely related to the hepatitis C Virus (HCV) but is more common than HCV among healthy blood donors. The pathogenicity of HGV in immunosuppressed patients such as those undergoing hemodialysis is unclear. We measured the incidence of HGV in 105 patients undergoing hemodialysis in a chronic outpatient hemodialysis facility. HGV-RNA was detected using a RT-PCR method with primers directed against the 5' non-coding region and the NS5a gene of HGV. Nine (8.6%) patients were HGV RNA positive, eleven (10.5%) were anti-HCV positive, three (2.9%) were positive for hepatitis B surface antigen. Four patients were positive for both HGV and HCV; three of them had normal liver enzymes while one showed elevated ALT levels but no other signs of exacerbation of preexisting hepatitis. The prevalence of HGV among dialysis patients is comparable to that of HCV. The transmission route for HCV is nosocomial transmission during dialysis, whereas HGV shows both ways of transmission: blood transfusion mediated by a high prevalence of HGV among healthy blood donors and nosocomial transmission. HGV appears to play a minor role in acute hepatitis, even in immunosuppressed patients.

Cancer in end-stage renal disease: potential factors involved -editorial-

Increased incidence of cancer at various sites is observed in patients with end-stage renal disease (ESRD). In particular, lymphomas and carcinomas of the kidney, prostate, liver and uterus show an enhanced prevalence in these subjects compared with the general population. A multitude of factors directly or indirectly associated with the renal disease and the treatment regimens may contribute to the increased tumor formation in these patients. Impaired function of the immune system and of DNA repair mechanisms as well as reduced antioxidant defense, accumulation of carcinogenic compounds partly due to reduced renal elimination as well as chronic infections and inflammations are found more frequently in patients with ESRD compared with the general population and may act in concert to accelerate malignant transformation and tumor formation.

Low-molecular but not high-molecular advanced glycation end products (AGEs) are removed by high-flux dialysis

BACKGROUND

Patients with end-stage renal disease (ESRD) display very high levels of advanced glycation end products (AGEs). These compounds are suspected to play a pathophysiological role in diabetic nephropathy and late diabetic cardiovascular complications. We investigated to what extent AGE levels can be reduced by high-flux dialysis.

PATIENTS AND METHODS

Ten ESRD patients were treated three times each with DIAPES and HF60, two different synthetic, high-flux hemodialysis membranes. The kinetics of AGE removal was studied by fluorescence spectroscopy (excitation 370 nm/ emission 440 nm) and by ELISA of serum samples and the removal of beta2-m was studied by immunonephelometry of plasma samples. Samples were taken during dialysis sessions at t = 0, 30 and 180 min. In addition, molecular weight distribution of AGE products in serum of three patients was analyzed by gel filtration and fluorescence detection.

RESULTS

A significant difference could be found when AGE levels in serum of controls (n = 10) were compared with serum AGE levels of ESRD patients (p < 0.01/fluorescence; p < 0.0001/ ELISA). After 3 h of dialysis AGE-related fluorescence in serum decreased by 25.5 +/- 6.8% for HF60 (p < 0.0001) and 24.3 +/- 6.9% tor DIAPES (p < 0.0001). The corresponding decline measured by ELISA was 23.3 +/- 8.9% for HF60 (p < 0.0001) and 26.1 +/- 7.0% for DIAPES (p < 0.0001). Both methods showed no significant differences for both types of dialysis membranes. Gel filtration revealed that the decrease of fluorescence can be attributed to the removal of AGE peptides with a molecular mass < 12 kDa, only. In the high molecular range (> 12 kDa) no removal but hemoconcentration was observed independent of the dialyzer type used. The reduction of beta2-m during 3 hours of dialysis was 61.8 +/- 6.9% for HF60 (p < 0.0001) and 161.7 +/- 7.0% for DIAPES (p < 0.0001).

CONCLUSION

Both high-flux dialyzers were equally effective to remove low-molecular AGE products, while AGE-modified proteins of higher molecular weight were only marginally affected. On the basis of our data we suggest the study of molecular mass-dependent uremic toxicity of AGEs and the examination of the influence of other treatment modalities on the level of high-molecular AGEs.

[Extracorporeal renal replacement therapies in acute renal failure]

The most serious forms of acute renal failure (ARF) are nowadays encountered in the intensive care unit (ICU), where up to 25% of new patients are reported to develop ARF. Lethality rates may reach 50 to 90% when the ARF is part of a multiple organ dysfunction syndrome. A multitude of extracorporeal procedures have been introduced into intensive care medicine. Applied with adequate skills and experience, most of these techniques will suffice to replace excretory renal function. However, because of low efficacy arterio-venous procedures (CAVH and CAVHD) have been abandoned for the veno-venous, pump-driven techniques (CVVH and CVVHD). Up to now, there is no consensus whether continuous or intermittent renal replacement therapy is more advantageous. In many cases, oliguric patients with circulatory instability will be treated by CVVH, even though there is no prospective study to show that in terms of outcome continuous treatment is superior to intermittent hemodialysis. It is equally conceivable to treat such patients with daily, prolonged (intermittent) hemodialysis. Apparently, the dose of replacement therapy, be it continuous filtration (36 to 48 l/24 h) or intermittent hemodialysis (daily 3 to 4 h) with a target BUN of less than 50 mg/dl, is more important than the modality of treatment. Moreover, there is good evidence that the use of biocompatible membranes (no complement- or leukocyte activation) is preferable and that with high-volume hemofiltration bicarbonate-containing replacement fluids should be used. However, despite all the technical advances, we firmly believe that the skills and the experience of those physicians and nurses who actually perform renal replacement therapy in the ICU are more important than the modality of treatment applied.

Iron metabolism in rhEPO-treated hemodialysis patients

A number of factors have been shown to limit the response to recombinant human erythropoietin (rhEPO). One major factor appears to be an inadequate iron supply to the bone marrow. Erythropoiesis is dependent upon a continuous supply of iron to the bone marrow. The rate at which iron can be drawn from existing stores may easily limit the rate of delivery for hemoglobin synthesis. This may result in "functional iron deficiency" which is distinct from "absolute iron deficiency" caused by depletion of iron stores. At present there are three main parameters available to clinicians wishing to monitor iron status in their patients: serum ferritin and transferrin saturation (TFS), which are indirect measurements, and the percentage of hypochromic red cells, which directly reflects marrow iron status. Ferritin levels should be measured before starting rhEPO therapy to ensure adequate iron stores (> 200 microg/l), and when patients move from the correction phase to the maintenance phase of therapy (have stores become depleted during the correction phase?). In addition, ferritin levels can give an indication of iron overload following excess parenteral iron administration. The TFS represents a balance between iron supply by the stores and demand by bone marrow. A saturation below 20% probably indicates iron-deficient erythropoiesis. However, this is an indirect measure of marrow iron supply and wide fluctuations have been observed when determined at different time points. The percentage of hypochromic red blood cells is measured by flow cytometry and a hypochromic subpopulation of more than 10% (normal percentage > 2.5%) indicates iron-deficient erythropoiesis. However, not all departments have access to the required equipment. The aim of iron supplementation is to provide sufficient iron for the correction phase and replace iron losses (1,500 - 3,000 mg/year in hemodialysis patients) during the maintenance phase of rhEPO therapy. This amounts to a daily iron need in the range of 5-7 mg, which is well above the normal dietary intake and absorptive capacity of the human intestine. Therefore there is a need for intravenous iron, in particular when the patient ha absolute or functional iron deficiency, is in tolerant of oral iron, or is not complying we with the oral regimen.