Vitamin E-bonded hemodialyzer improves atherosclerosis associated with a rheological improvement of circulating red blood cells

Red blood cell distribution width predicts mortality of adult patients receiving veno-arterial extracorporeal membrane oxygenation

BACKGROUND

Red blood cell distribution width (RDW) is a numerical measure of the variation in the size of circulating red blood cells. Recently, there is increasing interest in the role of RDW as a biomarker for inflammatory states and as a prognostication tool for a wide range of clinical manifestations. The predictive power of RDW on mortality among patients receiving mechanical circulatory support remains largely unknown.

METHODS

A retrospective analysis of 281 VA-ECMO patients at a tertiary referral academic hospital from 2009 to 2019 was performed. RDW was dichotomized with RDW-Low <14.5% and RDW-High ≥14.5%. The primary outcome was all-cause mortality at 30 days and 1 year. Cox proportional hazards models were used to examine the association between RDW and the clinical outcomes after adjusting for additional confounders.

RESULTS

281 patients were included in the analysis. There were 121 patients (43%) in the RDW-Low group and 160 patients (57%) in the RDW-High group. Survival to ECMO decannulation [RDW-H: 58% versus RDW-L: 67%, p = 0.07] were similar between the two groups. Patients in RDW-H group had higher 30-days mortality (RDW-H: 67.5% vs RDW-L: 39.7%, p < 0.001) and 1 year mortality (RDW-H: 79.4% vs RDW-L: 52.9%, p < 0.001) compared to patients in the RDW-L group. After adjusting for confounders, Cox proportional hazards model demonstrated that patients with high RDW had increased odds of mortality at 30 days (hazard ratio 1.9, 95% CI 1.2-3.0, p < 0.01) and 1 year (hazard ratio 1.9, 95% CI 1.3-2.8, p < 0.01) compared to patients with low RDW.

CONCLUSIONS

Among patients receiving mechanical circulatory support with VA-ECMO, a higher RDW was independently associated with increased 30-days and 1-year mortality. RDW may serve as a simple biomarker that can be quickly obtained to help provide risk stratification and predict survival for patients receiving VA-ECMO.

Transcranial Doppler Echography Measurement in Hemodialysis Patients: The Potential Role of Angiotensin II Receptor Blockades on Cerebrovascular Circulation

Background: Although hemodialysis (HD) patients have an elevated risk of strokes, there are few reports about transcranial doppler (TCD) echography measurements. It is well-known that angiotensin II receptor blockades (ARBs) protect against cardiovascular complications. In this study, we measured intracranial artery (ICA) velocity using TCD echography and studied the associated factors with its velocity in HD patients by a comparison with or without ARBs. Methods: We conducted a cross-sectional study in a single hospital. We included 61 patients who had measurable ICA velocity by TCD echography. Among them, the ARB usage group consisted of 22 subjects, whilst the non-ARB usage group consisted of 39 subjects. Results: Patients in the ARB (+) and ARB (-) groups did not show any difference in basic characteristics. ICA blood flow velocity in all intracranial arteries tended to show greater values in the ARB group than those in the non-ARB group. Particularly, blood velocity in the middle cerebral artery (MCA) (maximal flow velocity) statistically increased in the ARB group, respectively. In a univariate analysis, MCA maximum velocity was significantly associated with ARB usage (p = 0.011) and low hematocrit levels (p = 0.045). The multivariate analysis chose only ARB usage as an independent factor associated with left MCA maximum velocity (p = 0.022). Conclusions: We showed that dialysis patients with ARBs have significantly higher ICA blood velocity. ARBs might have a potential benefit for maintaining ICA blood flow in HD patients.

The Characteristics of Dialysis Membranes: Benefits of the AN69 Membrane in Hemodialysis Patients

Patients undergoing hemodialysis (HD) experience serious cardiovascular complications, through malnutrition, inflammation, and atherosclerosis. Amputation for peripheral arterial disease (PAD) is more prevalent in patients undergoing HD than in the general population. In addition, revascularization procedures in dialysis patients are often associated with subsequent amputation and high mortality rates. To improve the prognosis of dialysis patients, malnutrition and inflammation must be properly treated, which necessitates a better understanding of the characteristics of dialysis membranes. Herein, the characteristics of several dialysis membranes were studied, with a special reference to the AN69 membrane, noting several similarities to low-density lipoprotein (LDL)-apheresis, which is also applicable for the treatment of PAD. Both systems (LDL-apheresis and AN69) have anti-inflammatory and anti-thrombogenic effects because they use a negatively charged surface for extracorporeal adsorptive filtration from the blood/plasma, and contact phase activation. The concomitant use of both these therapeutic systems may have additive therapeutic benefits in HD patients. Here, we reviewed the characteristics of dialysis membranes and benefits of the AN69 membrane in dialysis patients.

Red Blood Cell Distribution Width as a Predictive Biomarker for Postoperative Infections in Children Who Underwent Cardiac Surgery: A Single-Center Retrospective Study

Background It has been investigated that red blood cell distribution width (RDW) is associated with the clinical outcomes of patients following surgeries and is used as a prognostic biomarker for postsurgical complications. In this study, we aimed to assess the value of RDW as a predictor of postoperative complications in children after cardiac surgeries. Methods Three hundred fifty-five pediatric patients who underwent cardiac surgery between 2017 and 2018 were enrolled, and preoperative and postoperative RDW values were determined. Data collected included demographics; incidence of postsurgical complications, including sepsis, surgical site infections (SSIs), urinary tract infections (UTIs), and ventilator-associated pneumonia (VAP); length of hospital and pediatric cardiac intensive care unit (PCICU) stay; and ventilator duration. Results Among children who underwent cardiac surgery, 29 (8.2%) of the cases developed bloodstream infections (BSIs), while urinary tract infections (UTIs) were observed in 32 (9.0%) of the cases, and ventilator-associated pneumonia (VAP) was observed in 36 of the cases (10.1%). Of all cases, surgical site infections (SSIs) were reported in 13 patients (3.7%). Significantly higher postoperative RDW levels were observed on days three (p-value=0.028), five (p-value=0.041), and seven (p-value=0.042) in cases of BSI. For UTI cases, only preoperative RDW levels (p<0.001) and postoperative day three RDW levels (p<0.049) were significantly higher than their counterparts. VAP cases had significantly higher RDW levels pre-operatively (p-value=0.002), which was also observed in postoperative RDW levels on days three (p-value=0.033), five (p-value=0.031), and seven (p-value=0.021) in comparison to their analogs (p-values<0.05). Furthermore, a significant relationship was found between preoperative RDW and length of intensive care unit (ICU) stay (95% CI 0.685-3.221, p-value=0.003, R2=0.104) and duration of mechanical ventilation (95% CI 0.549-1.938, p-value=0.001, R2=0.102). Conclusion RDW is a significant factor in predicting complications in pediatric patients' post-cardiac surgeries, including BSI, UTI, and VAP, which would consequently anticipate patients' clinical state after cardiac procedures.

Implications of advanced oxidation protein products and vitamin E in atherosclerosis progression

Introduction

Advanced oxidation protein products (AOPP) are considered as markers of oxidative stress and inflammation, and highly predictive of atherosclerosis. Vitamin E (Vit-E) is a powerful antioxidant, but no consensus on its effectiveness at the level of AOPP or the process of atherosclerosis has been made. Hence this was the aim of the present study.

Material and methods

A longitudinal study was conducted on 205 patients with chronic kidney disease (CKD) and 40 controls. The correlations between AOPP and glomerular filtration rate (GFR) and different biological markers were analyzed. Supra-aortic trunk echo-Doppler was conducted to assess the correlation of AOPP with intima-media thickness. The effects of Vit-E treatment on AOPP levels and atherosclerosis progression were also investigated.

Results

AOPP levels increased in parallel to the alteration of renal functions in CKD patients, compared to the control group (p < 0.05). The mean value of AOPP increased concomitantly with the intima-media thickness (p < 0.05). Furthermore, AOPP mean value was higher in patients with atherosclerotic plaques (p < 0.05) compared to those without plaques. Vit-E treatment stabilized the levels of AOPP but had no effect on the atherosclerotic progression.

Conclusions

AOPP were proved to be effective markers of oxidative stress and their high levels help to predict the progression of atherosclerosis. As a powerful antioxidant, Vit-E stabilized the AOPP levels.

Effects of Eucommia ulmoides leaf extracts on growth performance, antioxidant capacity and intestinal function in weaned piglets

Eucommia ulmoides is traditional Chinese medicine, and it possesses several potential bioactivities, such as anti-inflammatory, antioxidant and immune regulatory activities. This study was conducted to determine the effects of dietary Eucommia ulmoides leaf extracts (ELE) on growth performance, antioxidant capacity and intestinal function of weaned piglets. Two hundred crossbred (Duroc × Landrace × Yorkshire) piglets with an average initial weight of 12.96 ± 0.28 kg were randomly allotted to five treatments: C0 (basal diet), C1 (basal diet + antibiotics) and basal diet supplemented with increasing levels of ELE (0.2, 0.3 or 0.4 g/kg of feed). The results showed that ELE or antibiotics supplementation remarkably decreased diarrhoea rate and 0.3 g/kg ELE increased average daily gain compared with C0 (p < .05). 0.3 g/kg ELE increased alkaline phosphatase (AKP) levels and total antioxidant capacity (T-AOC) in serum and liver, as well as increased the content of serum albumin and total protein (TP) compared with the C0 (p < .05). The lipase activity of duodenum content and trypsin activity of jejunum content were improved fed diets containing 0.3 g/kg ELE compared with C0 (p < .05). The 0.3 g/kg ELE treatments have a higher villus height of the duodenum and jejunum compared with the C0 (p < .05). These results suggested that ELE supplementation had beneficial effects on antioxidant and intestinal function in weaned piglets, which also could increase growth performance and decreased diarrhoea rate. Accordingly, ELE is a potential alternative to antibiotics.

Changes in antioxidant status associated with haemodialysis in chronic kidney disease

Oxidative stress has been implicated in the pathogenesis, progression of chronic kidney disease (CKD) and development of cardiovascular complications. Hemodialysis (HD) has also been described to contribute significantly to oxidative stress in CKD patients, though reports are conflicting.

Objective

We evaluated the effects of one session of HD on the antioxidant capacity and lipid peroxidation in CKD patients.

Method

Thirty-six CKD patients requiring HD were recruited into this study. Participants were naïve to HD and each completed a session of three hours using polysulfone membrane dialyzers. Blood samples were collected before and after dialysis. Total antioxidant capacity (TAC) was measured by ferric reducing antioxidant power (FRAP) while malondialdehyde (MDA) was measured using thiobarbituric acid-reactive substance (TBARS). Comparison was made between pre-HD and post-HD values of TAC and MDA respectively, p value of <0.05 was taken as significant.

Result

Mean age and estimated glomerular filtration rate of subjects were 45 ±15 years and 6.3± 4.7mls/1.73m² respectively. There was significant decrease in the mean TAC from 1232.2 ± 495.6 µmol Trolox equiv/ to 832.4 ± 325.7 µmol Trolox equiv/L post-dialysis (p< 0.001) while MDA values were similar before and after HD (11.8 ± 1.8 vs 11.8 ± 2.331)µmol/L (p> 0.05). There was no significant association between changes in antioxidant status following HD with blood flow rate, ultrafiltration volume nor dialyzer per size.

Conclusion

A session of HD in patients with CKD is associated with significant reduction of the total antioxidants capacity; and no effect on MDA levels.

Funding

No external funding received.

Inverted U-shaped curve relationship between red blood cell distribution width and hypertension in a large health checkup population in China

This study was aimed at investigating the relationship between red blood cell distribution width (RDW) and hypertension in a large health check up population in China. A population of 302,527 subjects from Wuhu was enrolled in this cross-sectional health check up study between 2011 and 2016. They consisted of 126,369 women (41.78%) and 176,158 men (58.23%) with mean age of 46.9 ± 13.4 and 48.1 ± 13.7 years, respectively. The investigations included information on demographic characteristics, physical examination, and laboratory testing. Inverted U-shape relationships were observed between RDW and hypertension with peak RDW values of 14.2 (women) and 15.2 (men). After stratification by sex and adjusted with body mass index, age, white blood cells, and high-density lipoprotein cholesterol, inverted U-shape relationships were also established between RDW and hypertension, systolic blood pressure, and diastolic blood pressure, with peak RDW of 14.2, 14.5, 14.5 in women and 14.2, 16.0, 14.5 in men. Inverted U-shape relationship exists between RDW and hypertension, systolic blood pressure, and diastolic blood pressure among the Chinese health check up population studied.

Effect of Vitamin E-Coated Dialysis Membranes on Anemia in Patients with Chronic Kidney Disease: An Italian Multicenter Study

Background

Increased oxidant stress is increasingly recognized as a crucial factor in anemia in patients with chronic kidney disease. Vitamin E-coated membranes (VECMs) consist of a multilayer membrane with liposoluble vitamin E on the blood surface allowing direct free radical scavenging at the membrane site, which is of potential clinical benefit. Our objective was to examine the effect of VECMs on anemia in chronic hemodialysis (HD).

Methods

We enrolled 172 stable chronic HD patients (94 men, 78 women, age 65.4 ± 13.4 years) in an open-label multicenter study. They were shifted from their previous dialyzer to VECM for 1 year. Hemoglobin (Hb) levels and recombinant human erythropoietin (rHuEpo) dosage were analyzed after 4, 8, and 12 months on the VECM and compared with baseline values using paired tests.

Results

Hb significantly increased from 10.9 ± 1.2 g/dL at baseline to 11.7 ± 1.2 g/dL after 12 months (p<0.001) on VECMs. Conversely, the rHuEpo dosage decreased from 7,762 ± 5,865 IU/week at baseline to 6,390 ± 5,679 IU/week after 12 months (p<0.001). The proportion of patients who were at target Hb levels (European Best Practice Guidelines) increased from 49.4% at baseline to 80% after 12 months (p<0.001).

Conclusions

Dialysis with VECM in stable chronic HD patients was associated with significantly improved Hb levels and lower rHuEpo requirements. These results suggest that the antioxidant properties of VECMs may impact favorably on anemia management in chronic HD patients. Possible mechanisms include enhanced membrane biocompatibility, reduced oxidative stress and inflammation with VECMs, resulting in improved red blood cell survival and/or rHuEpo responsiveness. This therapy may potentially contribute to more effective anemia management in hemodialysis patients, and merits further rigorous study.

Red cell distribution width associated with adverse cardiovascular outcomes in patients with chronic kidney disease

Background

Recent studies have demonstrated that red cell distribution width (RDW) is associated with cardiovascular (CV) events and mortality. Patients with chronic kidney disease (CKD) are often anemic and have high RDW levels. In this study, we investigated the effect of RDW on major composite CV outcomes among patients with CKD.

Methods

We retrospectively analyzed patients with CKD who were admitted to the department of cardiology of a tertiary hospital in 2011. The patients were divided into 2 groups: normal RDW (RDW < 14.5%) and elevated RDW (RDW ≥ 14.5%). Demographic characteristics, comorbidities, blood investigation results, prescriptions, and outcomes were analyzed after a 3-year follow-up period. Six adjustment levels were performed to evaluate the effect of RDW on outcomes.

Results

This study involved 282 patients with CKD: 213 in the elevated RDW group and 69 in the normal RDW group. The elevated RDW group had older patients, a lower proportion of male patients, lower left ventricular ejection fraction (LVEF) values, lower hemoglobin levels, lower serum albumin levels, and higher creatinine levels, compared with the normal RDW group. A linear trend was observed toward higher RDW in patients with deteriorating renal function. In the final adjusted model, RDW ≥ 14.5%, older age, and lower LVEF were associated with an increased risk of major composite CV outcomes.

Conclusion

RDW is a potentially useful cost-effective indicator of major composite CV outcomes in patients with CKD.

Phytosterols improve immunity and exert anti-inflammatory activity in weaned piglets

BACKGROUND

Phytosterols (PS), plant-derived natural steroid compounds, are novel feed additives to regulate immune function and promote pig growth. This study was conducted to determine the effects of PS on the immune response of weaned piglets.

RESULTS

One hundred and twenty crossbred (Duroc × Landrace × Yorkshire) piglets with an average initial weight of 9.58 ± 0.26 kg were randomly allotted to three treatments. Treatments consisted of a control, PS (0.2 g kg^-1 ) and polymyxin E (0.04 g kg^-1 , antibiotic control) treatment. The results showed that PS or polymyxin E supplementation remarkably decreased diarrhea rate and elevated CD3⁺ CD4⁺ /CD3⁺ CD8⁺ ratio in piglets compared with the control (P < 0.05). PS increased basophil and serum interleukin-4, and caused a shift towards Th2 profile by decreasing Th1/Th2 ratios in piglets compared with control (P < 0.05). Polymyxin E contributed to an increase in interleukin-10 compared with the control (P < 0.05). No significant difference was observed in the amount of Lactobacillus, Bifidobacterium or Escherichia coli of jejunum among the three treatments (P > 0.05).

CONCLUSION

These results suggest that PS supplementation has no significant effect on growth but could remarkably decrease diarrhea rate, and improve immunity and anti-inflammatory activity in weaned piglets. In addition, PS supplementation had similar effects on growth, anti-inflammation and intestinal microorganisms as supplementation with polymyxin E in piglets. © 2017 Society of Chemical Industry.

Red cell distribution width (RDW) as a biomarker for respiratory failure in a pediatric ICU

Background

The red cell distribution width (RDW) is a widely available, inexpensive, and highly reproducible test that reflects the range of the red cell sizes. Any process that releases reticulocytes in the circulation will result in an increase in RDW. Elevated RDW values are linked to worsened pulmonary function in the adult population. We performed a retrospective cohort study to describe the association between RDW and respiratory failure in critically ill children in a in a pediatric intensive care unit (PICU) in a tertiary university hospital.

Subjects

All patients admitted between January 2009 and June 2015 were considered eligible for inclusion.

Methods

Retrospective cohort study.

Results

In total, 960 patients were included in the cohort analysis. Of those patients, 149 (15.5%) had elevated RDW values. RDW on admission was associated with lower 28 day ventilator-free days. The highest quintile of RDW was associated with the need for mechanical ventilation, even when correcting for anaemia, age and Pediatric Risk of Mortality (PRISM) scores. In the subgroup of ventilated patients, RDW was associated with nadir PaO₂/FiO₂(P/F) ratios.

Conclusion

The RDW value on admission of our PICU patients is associated with a greater need for invasive mechanical ventilation, lower 28 day ventilator-free days and lower nadir P/F ratios in the patients with highest RDW values on admission. RDW may be a valuable, cheap and universally available, prognostic parameter for respiratory dysfunction in the PICU.

Cardiovascular Events in Hemodialysis Patients: Challenging against Vascular Calcification

Particularly in patients with hemodialysis, cardiovascular mortality rate is extremely high. Polyvascular diseases develop at an early stage of chronic kidney disease (CKD). Pathophysiology includes insulin resistance and/or imbalance between nitric oxide (NO) and endothelin bioavailability as well as oxidative stress. The understanding in pathophysiology of vascular calcification and strategic treatment is a critical issue to achieve favorable outcome for the patients with CKD. In this article, we aim to review the cardiovascular disease for the patients with CKD with a particular emphasis on the clinical aspects of polyvascular disease. Finally, we address to detect microcirculatory impairment and eradicate vascular calcification as early as possible prior to renal replacement therapy. (This is a translation of Jpn J Vasc Surg 2016; 25: 359-365.).

Toward a Blood-Borne Biomarker of Chronic Hypoxemia: Red Cell Distribution Width and Respiratory Disease

Hypoxemia (systemic oxygen desaturation) marks the presence, risk, and progression of many diseases. Episodic or nocturnal hypoxemia can be challenging to detect and quantify. A sensitive, specific, and convenient marker of recent oxygen desaturation represents an unmet medical need. Observations of acclimatization to high altitude in humans and animals reveals several proteosomic, ventilatory, and hematological responses to low oxygen tension. Of these, increased red cell distribution width (RDW) appears to have the longest persistence. Literature review and analyses of a 2M patient database across the full disease pathome revealed that increased RDW is predictive of poor outcome for certain diseases including many if not all hypoxigenic conditions. Comprehensive review of diseases impacting the respiratory axis show many are associated with increased RDW and no apparent counterexamples. The mechanism linking RDW to outcome is unknown. Conjectural roles for iron deficiency, inflammation, and oxidative stress have not been born out experimentally. Sports-doping studies show that erythropoietin (EPO) injection can induce formation of unusually large red blood cells (RBC) in sufficient numbers to increase RDW. Because endogenous EPO responds strongly to hypoxemia, this molecule could potentially mediate a long-lived RDW response to low oxygenation. RDW may be a guidepost signaling that unexploited information is embedded in subtle RBC variation. Applying modern techniques of measurement and analysis to certain RBC characteristics may yield a more specific and sensitive marker of chronic pulmonary and circulatory diseases, sleep apnea, and opioid inhibition of breathing.

Relation of red cell distribution width to contrast-induced acute kidney injury in patients undergoing a primary percutaneous coronary intervention

BACKGROUND AND AIM

We investigated the utility of the preprocedural red cell distribution width (RDW) for predicting contrast-induced acute kidney injury (CI-AKI) in patients with ST-segment-elevation myocardial infarction (STEMI) who underwent a primary percutaneous coronary intervention.

MATERIALS AND METHODS

A total of 630 consecutive patients who were routinely referred to coronary angiography for STEMI were included in the present study.

RESULTS

CI-AKI was observed in 79 patients (12.5%). The RDW, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and the mean platelet volume were significantly higher in the CI-AKI group than in the non-CI-AKI group (P<0.001, P=032, P=0.025, and P=0.039, respectively). Serum total bilirubin and direct bilirubin levels were not different among the study groups. Using multivariate logistic regression analysis, we found that left ventricular ejection fraction [odds ratio (OR)=0.972, 95% confidence interval (CI) 0.945-0.998, P=0.033], estimated glomerular filtration rate (OR=0.970, 95% CI 0.959-0.981, P<0.001), contrast volume (OR=1.007, 95% CI 1.002-1.012, P=0.009), and RDW (OR=1.406, 95% CI 1.120-1.792, P=0.005) were independent predictors of CI-AKI.

CONCLUSION

Red blood cell distribution width, an inexpensive and easily measurable laboratory variable, is associated independently with the development of CI-AKI. Our data suggest that RDW may be a useful marker in CI-AKI risk stratification.

The Prognostic Role of Red Blood Cell Distribution Width in Coronary Artery Disease: A Review of the Pathophysiology

Red blood cell distribution width (RDW) is a measure of red blood cell volume variations (anisocytosis) and is reported as part of a standard complete blood count. In recent years, numerous studies have noted the importance of RDW as a predictor of poor clinical outcomes in the settings of various diseases, including coronary artery disease (CAD). In this paper, we discuss the prognostic value of RDW in CAD and describe the pathophysiological connection between RDW and acute coronary syndrome. In our opinion, the negative prognostic effects of elevated RDW levels may be attributed to the adverse effects of independent risk factors such as inflammation, oxidative stress, and vitamin D₃ and iron deficiency on bone marrow function (erythropoiesis). Elevated RDW values may reflect the intensity of these phenomena and their unfavorable impacts on bone marrow erythropoiesis. Furthermore, decreased red blood cell deformability among patients with higher RDW values impairs blood flow through the microcirculation, resulting in the diminution of oxygen supply at the tissue level, particularly among patients suffering from myocardial infarction treated with urgent revascularization.

Triggers, inhibitors, mechanisms, and significance of eryptosis: the suicidal erythrocyte death

Suicidal erythrocyte death or eryptosis is characterized by erythrocyte shrinkage, cell membrane blebbing, and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include Ca(2+) entry, ceramide formation, stimulation of caspases, calpain activation, energy depletion, oxidative stress, and dysregulation of several kinases. Eryptosis is triggered by a wide variety of xenobiotics. It is inhibited by several xenobiotics and endogenous molecules including NO and erythropoietin. The susceptibility of erythrocytes to eryptosis increases with erythrocyte age. Phosphatidylserine exposing erythrocytes adhere to the vascular wall by binding to endothelial CXC-Motiv-Chemokin-16/Scavenger-receptor for phosphatidylserine and oxidized low density lipoprotein (CXCL16). Phosphatidylserine exposing erythrocytes are further engulfed by phagocytosing cells and are thus rapidly cleared from circulating blood. Eryptosis eliminates infected or defective erythrocytes thus counteracting parasitemia in malaria and preventing detrimental hemolysis of defective cells. Excessive eryptosis, however, may lead to anemia and may interfere with microcirculation. Enhanced eryptosis contributes to the pathophysiology of several clinical disorders including metabolic syndrome and diabetes, malignancy, cardiac and renal insufficiency, hemolytic uremic syndrome, sepsis, mycoplasma infection, malaria, iron deficiency, sickle cell anemia, thalassemia, glucose 6-phosphate dehydrogenase deficiency, and Wilson's disease. Facilitating or inhibiting eryptosis may be a therapeutic option in those disorders.

Oxidative stress and suicidal erythrocyte death

SIGNIFICANCE

Eryptosis, the suicidal erythrocyte death, is characterized by cell shrinkage, membrane blebbing, and phosphatidylserine translocation to the outer membrane leaflet. Phosphatidylserine at the erythrocyte surface binds endothelial CXCL16/SR-PSOX (CXC-Motiv-Chemokin-16/Scavenger-receptor-for-phosphatidylserine-and-oxidized-low-density-lipoprotein) and fosters engulfment of affected erythrocytes by phagocytosing cells. Eryptosis serves to eliminate infected or defective erythrocytes, but excessive eryptosis may lead to anemia and may interfere with microcirculation. Clinical conditions with excessive eryptosis include diabetes, chronic renal failure, hemolytic uremic syndrome, sepsis, malaria, iron deficiency, sickle cell anemia, thalassemia, glucose 6-phosphate dehydrogenase deficiency, glutamate cysteine ligase modulator deficiency, and Wilson's disease.

RECENT ADVANCES

Eryptosis is triggered by a wide variety of xenobiotics and other injuries such as oxidative stress. Signaling of eryptosis includes prostaglandin E₂ formation with subsequent activation of Ca(2+)-permeable cation channels, Ca(2+) entry, activation of Ca(2+)-sensitive K(+) channels, and cell membrane scrambling, as well as phospholipase A2 stimulation with release of platelet-activating factor, sphingomyelinase activation, and ceramide formation. Eryptosis may involve stimulation of caspases and calpain with subsequent degradation of the cytoskeleton. It is regulated by AMP-activated kinase, cGMP-dependent protein kinase, Janus-activated kinase 3, casein kinase 1α, p38 kinase, and p21-activated kinase 2. It is inhibited by erythropoietin, antioxidants, and further small molecules.

CRITICAL ISSUES

It remains uncertain for most disorders whether eryptosis is rather beneficial because it precedes and thus prevents hemolysis or whether it is harmful because of induction of anemia and impairment of microcirculation.

FUTURE DIRECTIONS

This will address the significance of eryptosis, further mechanisms underlying eryptosis, and additional pharmacological tools fostering or inhibiting eryptosis.

Towards online, continuous monitoring for rheometry of complex fluids

This paper presents an overview of the developments that have been made towards the design of an inline rheometer that has the capabilities for monitoring in real time the viscous constitutive parameters of non-Newtonian fluids in a pipe flow. This has potential applications for a wide range of fluids, including hydrocolloid solutions and polymer solutions. This is of relevance to many industries, for example the pharmaceutical, lubrication, food and printing industries. The use of mathematical algorithms for inferring rheological parameters from properties of flow field statistics is explored. Particular focus is given to the development of a flow cell rheometer containing a T-junction geometry with the capacity to induce a range of shear rates in the vicinity of the bend, and a distribution of elongational viscosities along the back-wall. Such features create an information-rich flow field that is beneficial for the development of a rheometer with a fast response time that is suitable for commercial purposes.

Impact of inflammation on anti-oxidative effects of vitamin E-coated membrane dialyzer in patients on chronic hemodialysis

Hemodialysis (HD) with the use of vitamin E-coated membrane (VEM) dialyzers is shown to exert anti-inflammatory and antioxidative effects in patients with end-stage renal disease on HD. However, the association of baseline inflammatory status with the antioxidative effects of VEM has not been investigated thus far. Thirty-five stable end-stage renal disease patients treated with VEM for 6 months were enrolled in the present prospective, observational cohort study. For the previous 3 months minimum, 17 (48%) patients were dialyzed with a cellulose, eight (23%) patients with a hemophane, and 10 (29%) patients with a polysulfone 1.2 to 1.5 m(2) hollow fiber dialyzer. The effects of treatment on oxidized low-density lipoprotein (oxLDL) were stratified according to half percentiles of baseline serum logC-reactive protein and interleukin-6, and the association between treatment goal, arbitrarily defined as a minimum 30% decrease in baseline oxLDL, was assessed with the use of logistic regression analysis. The higher C-reactive protein and interleukin-6 half percentiles were independently and additively associated with a higher odds ratio for achieving treatment goal. Adjustment for baseline oxLDL, age, sex, HD duration, smoking, and body mass index did not attenuate the odds ratios, whereas the history of diabetes, as primary renal disease, significantly decreased the odds ratio for achieving treatment goal. Increased baseline C-reactive protein and interleukin-6 are independent, additive factors associated with the effect of VEM on oxLDL in HD patients.

A randomized controlled trial evaluating the erythropoiesis stimulating agent sparing potential of a vitamin E-bonded polysulfone dialysis membrane

Background

Vitamin E (VE) bonded polysulfone dialysis membranes have putative erythropoiesis stimulating agent (ESA)-sparing and anti-inflammatory properties based on data from a small number of studies. We sought to investigate this in a large, prospective 12-month randomized controlled trial.

Methods

Two-hundred and sixty prevalent haemodialysis (HD) patients were randomized to dialysis with VE-bonded polysulfone membranes or non-VE-bonded equivalents. All ESA-dosing was performed by means of a computer-based anaemia management decision support system. Monthly data were used to calculate the ESA resistance index (ERI) and blood tests were performed at baseline, 6 and 12 months for measurement of C-reactive protein (CRP) levels.

Results

Of the 260 patients, 123 were randomized to dialysis with the VE-membrane and 12-month data was available for 220 patients. At the study population level, no beneficial effect of the VE membranes on the ERI or CRP levels was observed. Post hoc analyses indicated that there was a significant fall in ERI for patients with the highest baseline ESA resistance dialysed with the VE (9.28 [7.70–12.5] versus 7.70 [5.34–12.7] IU/week/kg/g/dL Hb, P = 0.01) but not the control membranes (9.45 [7.62–12.3] versus 8.14 [4.44–15.6] IU/week/kg/g/dL Hb, P = 0.41); this was not attributable to changes in CRP levels.

Conclusions

Wholesale switching of all chronic HD patients to dialysis with VE-bonded polysulfone membranes appears not to be associated with improvements in ESA-responsiveness or CRP. These membranes may have utility in patients with heightened ESA resistance.

Hematologic variables and venous thrombosis: red cell distribution width and blood monocyte count are associated with an increased risk

Recent studies suggest that leukocytes and erythrocytes play a role in coagulation. However, whether leukocytes, erythrocytes and other hematologic variables are associated with risk of venous thrombosis is not well known. To study this, we used data from 2473 patients with venous thrombosis and 2935 controls. The variables assessed were: total leukocytes, granulocytes, lymphocytes, monocytes, hematocrit, hemoglobin, erythrocytes and red cell indices (mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration and red cell distribution width). We found a strong dose-response relation for higher red cell distribution width and monocyte count with risk of venous thrombosis, with odds ratios of 3.1 (95% confidence interval, 2.0-4.8) and 2.8 (95% confidence interval, 1.3-5.8), respectively, after adjustment for age, sex, C-reactive protein level, malignancy and co-morbidities. Monocyte count and red cell distribution width were associated with venous thrombosis even within reference ranges. A low monocyte count (<0.12 × 10(9)/L) was associated with a lower risk of venous thrombosis after full adjustment (odds ratios 0.6; 95% confidence interval, 0.4-0.8). In summary, high red cell distribution width and blood monocyte count, two parameters that are inexpensive and easily obtainable, were clearly associated with an increased risk of venous thrombosis. Future studies should evaluate the underlying mechanism and the use of these variables in prediction models for first and recurrent thrombosis.

Efficacy of vitamin E-bonded polysulfone dialyzer and polysulfone dialyzer on a series of non-anticoagulant hemodialysis

Non-anticoagulant hemodialysis is conducted occasionally at limited numbers of hospitals on an empirical basis. This study examines the efficacy of polysulfone and vitamin E-bonded polysulfone dialyzer for non-anticoagulant hemodialysis. These dialyzers were assigned one after the other for a vintage hemodialysis patient complicated with uncontrollable bleeding. The patient's vital and console data throughout non-anticoagulant hemodialysis were monitored serially. Both dialyzers were reasonably applicable to hemodialysis without major clotting. The scheduled treatment period was completed. Vitamin E-bonded polysulfone dialyzer was superior to non-anticoagulant hemodialysis based on venous pressure observed during treatment.

Randomized controlled open-label trial of vitamin E-bonded polysulfone dialyzer and erythropoiesis-stimulating agent response

BACKGROUND AND OBJECTIVES

A 1-year multicenter prospective randomized controlled study was conducted on the effects of vitamin E-bonded polysulfone dialyzers on erythropoiesis-stimulating agent response in hemodialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Major inclusion criteria were use of high-flux polysulfone dialyzers with 50-70 ml/min β2-microglobulin clearance over 3 months, transferrin saturation over 20%, same erythropoiesis-stimulating agent for over 3 months, and hemoglobin at 10-12 g/dl. Hemodialysis patients were placed in four interventional groups: two hemoglobin ranges (10.0-10.9 or 11.0-11.9 g/dl) and two dialyzers. Patients were randomly assigned by central registration to a vitamin E-bonded polysulfone dialyzers or polysulfone control group. Primary end point was relative erythropoiesis resistance index at baseline between groups at 12 months. Erythropoiesis resistance index was defined as total weekly erythropoiesis-stimulating agent dose divided by hemoglobin.

RESULTS

There were no statistically significant differences in age or sex. There was no significant difference in relative erythropoiesis resistance index between vitamin E-bonded polysulfone dialyzers and control groups at 12 months (vitamin E-bonded polysulfone dialyzers: 1.1, control: 1.3). The vitamin E-bonded polysulfone dialyzers group showed better relative erythropoiesis resistance index than the control group at 11.0-11.9 g/dl hemoglobin (vitamin E-bonded polysulfone dialyzers: 1.0, control: 1.4 at 12 months, significant difference) but no difference at 10.0-10.9 g/dl hemoglobin.

CONCLUSIONS

The overall relative erythropoiesis resistance index showed no difference between the vitamin E-bonded polysulfone dialyzers and control groups, although the change in relative erythropoiesis resistance index differed according to hemoglobin level.

The relationship between red cell distribution width with erythropoietin resistance in iron replete hemodialysis patients

BACKGROUND

Recently, erythropoietin resistance (ER) has been shown to be related with cardiovascular and overall mortality in hemodialysis (HD) patients. Red blood cell distribution width (RDW) has also shown to be associated with cardiovascular and all cause mortality in general population. Thus in the current study we tested the hypothesis that RDW and erythropoietin resistance as determined by erythropoiesis stimulating agents (ESA) hyporesponsiveness index (EHRI) may be related with each other in iron replete HD patients.

METHODS

Study participants underwent medical history taking, physical examination, calculation of dialysis adequacy and biochemical analysis. EHRI was calculated as the weekly dose of EPO divided by per kilogram of body weight divided by the hemoglobin level.

RESULTS

Two separate analyses were performed. In the first analysis performed in 94 HD patients; the stepwise linear regression analysis revealed that being female (P=0.031), HD duration (P=0.021), presence of diabetes mellitus (P=0.008), RDW (P=0.023), and predialysis sodium (P=0.05) were independently related with logarithmically converted EHRI. We made second analysis after 4 months. The second analysis revealed that when compared to first EHRI, the EHRI was increased in 40, unchanged in one and decreased in 40 patients The second stepwise regression analysis also showed that the independent relationship with RDW and EHRI was persisted (β=0.050, CI: 0.022-0.078, P=0.001).

CONCLUSION

Red blood cell distribution width was independently related with EHRI in iron replete HD patients.

Elevated red blood cell distribution width is associated with higher recourse to coronary artery bypass graft

BACKGROUND

Red blood cell distribution width (RDW) is a measure of heterogeneity in erythrocyte size used in the differential diagnosis of anemia. High levels are associated with elevated cardiovascular biomarkers and increased mortality. The hypothesis of this study is that high RDW levels on admission are associated with higher recourse to coronary artery bypass graft (CABG) in unstable angina (UA) or non-ST-elevation myocardial infarction (NSTEMI) patients.

METHODS

An observational, cross-sectional study of all adult patients undergoing coronary angiography admitted to an urban tertiary care center in 2007 with UA or NSTEMI was conducted. Data was gathered by review of inpatient charts. RDW was considered 'high' if it exceeded the 95th percentile (16.3%).

RESULTS

Among the 503 subjects included in the analysis, high RDW was independently associated with higher recourse to CABG versus a nonsurgical approach [OR = 2.39 (1.04-5.50); p = 0.041] but not with conservative management [OR = 0.97 (0.51-1.84); p = 0.922] or percutaneous coronary intervention [OR = 0.67 (0.36-1.25); p = 0.208].

CONCLUSIONS

This study of patients with UA or NSTEMI demonstrated an independent association of elevated RDW with higher recourse to CABG. RDW should be considered in the stratification of patients presenting with UA or NSTEMI.

Evaluation of the impact of a new synthetic vitamin E-bonded membrane on anemia and rHuEPO requirement in ESRD patients with central venous catheters: a pilot study

In the last years, the number of hemodialysis (HD) patients with erythropoietin (rHuEPO) resistance is increasing. Probably, central venous catheters (CVCs) contribute to this resistance by inducing inflammation and oxidative stress. This study was aimed to compare vitamin E-bonded dialyzer (PSVE) versus polyethersulfone membrane. Sixteen subjects with CVCs were included in a prospective two-arm crossover 12-month study. The primary endpoints were the rHuEPO requirement and the erythropoiesis-stimulating agents (ESA) index, which was defined by the ratio between weekly EPO dosage (IU/kg/week) and Hb levels (g/dl). The mean dosages of rHuEPO to maintain hemoglobin between 10.5 and 12 g/dl were 135 ± 59 and 101 ± 57 IU/kg/week with polysulfone and PSVE, respectively (P = 0.14). The ESA indexes were 12.1 ± 5.2 and 8.7 ± 5.2 (P < 0.0001) with polysulfone and PSVE, respectively. A trend towards consensual changes in protein glycoxidation, antioxidant, and inflammatory markers was observed. In conclusion, the study suggests a role for PSVE in the reduction of ESA index in HD patients with CVCs.

Differences in associated factors between aortic and mitral valve calcification in hemodialysis

Increased prevalence of aortic and mitral valve calcification has been reported in patients on hemodialysis, but it remains unknown whether aortic and mitral valve calcification arise from similar pathogenesis. We detected heart valve calcification using two-dimensional echocardiography, and we related valve calcification to various clinical parameters in patients treated with hemodialysis three times a week for more than 1 year. In 112 patients (77 men and 35 women, age 67+/-10 years, duration on hemodialysis 95+/-67 months), aortic and mitral valve calcification were observed in 84 (75.0%) and 58 (51.7%) patients, respectively. Aortic valve calcification was associated with increased age, higher serum calcium, lower serum albumin, lower total cholesterol and higher high-sensitivity C-reactive protein. Multivariate analysis showed that increased age and higher serum calcium were independently associated with aortic valve calcification. Conversely, mitral valve calcification was associated with increased age, higher high-sensitivity C-reactive protein and higher serum beta(2)-microglobulin, but not with higher serum calcium. In multivariate analysis, increased age and higher serum beta(2)-microglobulin were independently associated with mitral valve calcification. Serum beta(2)-microglobulin was associated with longer duration on hemodialysis, malnutrition inflammation (lower serum albumin and higher high-sensitivity C-reactive protein) and dyslipidemia. Considering the results in previous studies showing that the distribution of beta(2)-microglobulin amyloid deposition was consistent with that of tissue calcification in patients on hemodialysis, beta(2)-microglobulin may have pathogenic roles in valve calcification.

Red cell distribution width and mortality in older adults: a meta-analysis

BACKGROUND

Red cell distribution width (RDW) is a quantitative measure of variability in the size of circulating erythrocytes with higher values reflecting greater heterogeneity in cell sizes. Recent studies have shown that higher RDW is associated with increased mortality risk in patients with clinically significant cardiovascular disease (CVD). Whether RDW is prognostic in more representative community-based populations is unclear.

METHODS

Seven relevant community-based studies of older adults with RDW measurement and mortality ascertainment were identified. Cox proportional hazards regression and meta-analysis on individual participant data were performed.

RESULTS

Median RDW values varied across studies from 13.2% to 14.6%. During 68,822 person-years of follow-up of 11,827 older adults with RDW measured, there was a graded increased risk of death associated with higher RDW values (p < .001). For every 1% increment in RDW, total mortality risk increased by 14% (adjusted hazard ratio [HR]: 1.14; 95% confidence interval [CI]: 1.11-1.17). In addition, RDW was strongly associated with deaths from CVD (adjusted HR: 1.15; 95% CI: 1.12-1.25), cancer (adjusted HR: 1.13; 95% CI: 1.07-1.20), and other causes (adjusted HR: 1.13; 95% CI: 1.07-1.18). Furthermore, the RDW-mortality association occurred in all major demographic, disease, and nutritional risk factor subgroups examined. Among the subset of 1,603 older adults without major age-associated diseases, RDW remained strongly associated with total mortality (adjusted HR: 1.32; 95% CI: 1.21-1.44).

CONCLUSIONS

RDW is a routinely reported test that is a powerful predictor of mortality in community-dwelling older adults with and without age-associated diseases. The biologic mechanisms underlying this association merit investigation.

Increased leukocyte aggregates are associated with atherosclerosis in patients with hemodialysis

Little data are available on the role of blood rheology in atherosclerosis in hemodialysis (HD) patients. This study sought to assess the relationship between leukocytes conjugated with platelets (leukocyte aggregates [LA]) and atherosclerosis in patients with HD. The present study included 118 patients on HD. As surrogate markers of atherosclerosis, aortic stiffness measured by brachial-ankle pulse wave velocity, and carotid intima-media thickness (IMT) were measured. As an assessment of LA, a method, microchannel array flow analyzer, which makes it possible to directly observe the flow of blood cell elements through the microchannel, was used. We measured a number of LA during 50 microL flow of whole blood through microchannels. In 12 age-matched healthy individuals, a number of LA during 50 microL flow of whole blood was 25.7+/-5.4, whereas in HD patients it was significantly increased up to 48.2+/-16.4 (P<0.001). Flow cytometry demonstrated that LA were predominantly monocytes. Leukocyte aggregates were positively associated with plasma levels of fibrinogen (P<0.01), or serum high-sensitive C-reactive protein (P<0.01). Moreover, LA had highly significant associations with brachial-ankle pulse wave velocity (P<0.001) and IMT (P<0.001). In conclusion, we demonstrated hemorheologically that monocyte-platelet conjugates play an important role in aortic stiffness and IMT in HD patients.

Red blood cell distribution width and the risk of death in middle-aged and older adults

BACKGROUND

Red blood cell distribution width (RDW), a component of an electronic complete blood count, is a measure of heterogeneity in the size of circulating erythrocytes. In patients with symptomatic cardiovascular disease (CVD), RDW is associated with mortality. However, it has not been demonstrated that RDW is a predictor of mortality independent of nutritional deficiencies or in the general population.

METHODS

Red blood cell distribution width was measured in a national sample of 8175 community-dwelling adults 45 years or older who participated in the 1988-1994 National Health and Nutrition Examination Survey; mortality follow-up occurred through December 31, 2000. Deaths from all causes, CVD, cancer, and other causes were examined as a function of RDW.

RESULTS

Higher RDW values were strongly associated with an increased risk of death. Compared with the lowest quintile of RDW, the following were adjusted hazard ratios (HRs) for all-cause mortality (and 95% confidence intervals [CIs]): second quintile, HR, 1.1 (95% CI, 0.9-1.3); third quintile, HR, 1.2 (95% CI, 1.0-1.4); fourth quintile, HR, 1.4 (95% CI, 1.2-1.8); and fifth quintile, HR, 2.1 (95% CI, 1.7-2.6). For every 1% increment in RDW, all-cause mortality risk increased by 22% (HR, 1.22; 95% CI, 1.15-1.30; P < .001). Even when analyses were restricted to nonanemic participants or to those in the reference range of RDW (11%-15%) without iron, folate, or vitamin B(12) deficiency, RDW remained strongly associated with mortality. The prognostic effect of RDW was observed in both middle-aged and older adults for multiple causes of death.

CONCLUSION

Red blood cell distribution width is a widely available test that is a strong predictor of mortality in the general population of adults 45 years or older.

Association of heart valve calcification with malnutrition-inflammation complex syndrome, beta-microglobulin, and carotid intima media thickness in patients on hemodialysis

Heart valve calcification is an important predictor for all-cause and cardiovascular mortality in hemodialysis patients. Recently, serum beta(2)-microglobulin has been associated with cardiovascular disease in the non-hemodialysis population, but the relationship between serum beta(2)-microglobulin and valve calcification remains unknown. In this cross-sectional study, we recorded the patients' clinical parameters, including serum beta(2)-microglobulin, and related these parameters to the number of calcified valves detected by echocardiography. The patients included 80 males and 35 females (age 67 +/- 10 years; duration on hemodialysis 96 +/- 67 months). Calcification of the aortic and mitral valves was observed in 89 (77.4%) and 59 patients (51.3%), respectively. Fifty-one patients (44.3%) showed calcification of both valves. In univariate analysis, age (r = 0.301, P = 0.001), serum albumin (r = -0.219, P = 0.01), calcium (r = 0.205, P = 0.02), high sensitivity C-reactive protein (r = 0.209, P = 0.02), and beta(2)-microglobulin (r = 0.206, P = 0.02) significantly correlated with the number of calcified valves. Stepwise multiple regression analysis showed that age (beta = 0.389, P < 0.001) and calcium (beta = 0.223, P = 0.01) were independent determinants for valve calcification (r(2) = 0.195). In addition, carotid intima media thickness was significantly higher in patients with valve calcification compared with those without valve calcification. Our results suggested the impacts of calcium metabolism and malnutrition-inflammation complex syndrome on valve calcification. In addition, serum beta(2)-microglobulin may be another potential marker of cardiovascular complications in patients on hemodialysis.

Associations of renal vascular resistance with albuminuria and other macroangiopathy in type 2 diabetic patients

OBJECTIVE

Albuminuria can be caused by endothelial dysfunction as a result of ischemic nephropathy rather than classic diabetic nephropathy. We studied whether renal vascular resistance (resistive index [RI]) of the main renal arteries could be associated with albuminuria and further assessed the relationship between RI and aorta stiffness measured by brachial-ankle pulse-wave velocity (baPWV).

RESEARCH DESIGN AND METHODS

We consecutively studied 150 patients with type 2 diabetes and the absence of clinically overt renal artery stenosis. Renal function expressed as the estimated glomerular filtration rate (eGFR) was calculated using the modified formula of modification of diet in renal disease (MDRD). The RI [(peak systolic velocity -end-diastolic velocity)/peak systolic velocity] was measured with duplex Doppler ultrasonography.

RESULTS

When the presence of albuminuria (uAlb) was defined as urinary albumin-to-creatinine ratio (microg/mg x creatinine) >30, mean RI [(left RI + right RI)/2] was significantly higher in uAlb, compared with that in patients without uAlb. RI had significant associations with age (r = 0.398, P < 0.0001), diastolic blood pressure (r = -0.398, P < 0.0001), eGFR (r = -0.373, P < 0.0001), and baPWV (r = 0.223, P < 0.05), respectively. Multivariate logistic regression analysis showed that increased RI when defined as RI >0.72 (median) was significantly associated with age (P < 0.01, 95%CI 1.02-1.19), diastolic blood pressure (P < 0.01, 0.86-0.97), and uAlb (P < 0.01, 1.53-15.46), respectively. Moreover, RI was an independent risk factor for uAlb after adjustment of both diastolic blood pressure and eGFR.

CONCLUSIONS

Renal vascular resistance was associated with albuminuria and aorta stiffness. Increased RI may imply the presence of any type of underlying renal damage, including ischemic nephropathy.

Cardiovascular disease in dialysis patients: do some antihypertensive drugs have specific antioxidant effects or is it just blood pressure reduction? Does antioxidant treatment reduce the risk for cardiovascular disease?

PURPOSE OF REVIEW

Patients with end-stage renal disease have an extremely high cardiovascular disease mortality. Oxidative stress is one of the 'nontraditional' risk factors for cardiovascular disease mortality in dialysis patients. This review discusses antioxidant activity of the commonly prescribed antihypertensive agents and the effects of antioxidant interventions on cardiovascular disease mortality in patients with end-stage renal disease.

RECENT FINDINGS

Several lines of evidence confirm antioxidant activity of the renin-angiotensin-aldosterone antagonists, some of the calcium channel blockers, carvedilol, and hydralazine. This appears to be independent of their antihypertensive activity. Clinical evidence of their superiority in improving cardiovascular disease endpoints in end-stage renal disease, however, is lacking. There are no randomized trials that have examined the effect of correcting oxidative stress on clinical endpoints. One randomized study in patients on hemodialysis reported a reduction in oxidative stress and the plasma methylarginines with valsartan and amlodipine but no clinical endpoints were examined.

SUMMARY

The effects of the antihypertensive agents with antioxidant activity on cardiovascular disease mortality in end-stage renal disease have not been examined in randomized clinical trials. These agents may offer specific clinical advantage in addition to lowering the blood pressure, but this remains to be proven. Two studies show a reduction in cardiovascular disease events with vitamin E and N-acetylcysteine in patients on hemodialysis without an effect on overall mortality.

Erythropoiesis-stimulating agent hyporesponsiveness

Approximately 5-10% of patients with chronic kidney disease demonstrate hyporesponsiveness to erythropoiesis-stimulating agents (ESA), defined as a continued need for greater than 300 IU/kg per week erythropoietin or 1.5 mug/kg per week darbepoetin administered by the subcutaneous route. Such hyporesponsiveness contributes significantly to morbidity, mortality and health-care economic burden in chronic kidney disease and represents an important diagnostic and management challenge. The commonest causes of ESA resistance are non-compliance, absolute or functional iron deficiency and inflammation. It is widely accepted that maintaining adequate iron stores, ideally by administering iron parenterally, is the most important strategy for reducing the requirements for, and enhancing the efficacy of ESA. There have been recent epidemiologic studies linking parenteral iron therapy to an increased risk of infection and atherosclerosis, although other investigations have refuted this. Inflammatory ESA hyporesponsiveness has been reported to be improved by a number of interventions, including the use of biocompatible membranes, ultrapure dialysate, transplant nephrectomy, ascorbic acid therapy, vitamin E supplementation, statins and oxpentifylline administration. Other variably well-established causes of ESA hyporesponsiveness include inadequate dialysis, hyperparathyroidism, nutrient deficiencies (vitamin B12, folate, vitamin C, carnitine), angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, aluminium overload, antibody-mediated pure red cell aplasia, primary bone marrow disorders, myelosuppressive agents, haemoglobinopathies, haemolysis and hypersplenism. This paper reviews the causes of ESA hyporesponsiveness and the clinical evidence for proposed therapeutic interventions. A practical algorithm for approaching the investigation and management of patients with ESA hyporesponsiveness is also provided.

Vitamin E in renal therapeutic regiments

Administration of vitamin E in children with immunoglobulin A (IgA) nephropathy, focal segmental glomerulosclerosis (FSGS) and type I diabetes demonstrated potential towards ameliorating progression. Oral vitamin E therapy reduced endothelial dysfunction, lipid peroxidation and oxidative stress in patients with chronic kidney failure (CKF). Moreover, the use of vitamin E-bonded hemodialyzers reduced atherosclerotic changes, erythropoietin dosage and muscular cramps in patients on hemodialysis (HD). However, several controlled clinical trials failed to document beneficial effects on the study subjects' cardiovascular and renal outcomes. A recent report of increased all-cause mortality in adult patients receiving high dose vitamin E therapy has caused considerable concern and debate. These issues regarding the efficacy and safety of vitamin E in renal therapeutic regimens will be reviewed in this article.

Mechanisms and significance of eryptosis

Suicidal death of erythrocytes (eryptosis) is characterized by cell shrinkage, membrane blebbing, activation of proteases, and phosphatidylserine exposure at the outer membrane leaflet. Exposed phosphatidylserine is recognized by macrophages that engulf and degrade the affected cells. Eryptosis is triggered by erythrocyte injury after several stressors, including oxidative stress. Besides caspase activation after oxidative stress, two signaling pathways converge to trigger eryptosis: (a) formation of prostaglandin E(2) leads to activation of Ca(2+)-permeable cation channels, and (b) the phospholipase A(2)-mediated release of platelet-activating factor activates a sphingomyelinase, leading to formation of ceramide. Increased cytosolic Ca(2+) activity and enhanced ceramide levels lead to membrane scrambling with subsequent phosphatidylserine exposure. Moreover, Ca(2+) activates Ca(2+)-sensitive K(2+) channels, leading to cellular KCl loss and cell shrinkage. In addition, Ca(2+) stimulates the protease calpain, resulting in degradation of the cytoskeleton. Eryptosis is inhibited by erythropoietin, which thus extends the life span of circulating erythrocytes. Eryptosis may be a mechanism of defective erythrocytes to escape hemolysis. Conversely, excessive eryptosis favors the development of anemia. Conditions with excessive eryptosis include iron deficiency, lead or mercury intoxication, sickle cell anemia, thalassemia, glucose 6- phosphate dehydrogenase deficiency, malaria, and infection with hemolysin-forming pathogens.

Development of vitamin E-modified polysulfone membrane dialyzers

Oxygen radicals have recently been attracting close attention because of their involvement in tissue damage and their close relationship to various clinical conditions. It has been suggested that hemodialysis increases oxidative stress, triggering the development of complications such as atherosclerosis and dialysis-related amyloidosis. We recently developed a dialyzer containing a highly functional polysulfone membrane on which vitamin E had been bonded (PS-ViE). The present study was undertaken to evaluate the biocompatibility of this membrane and to conduct other experiments on the membrane in vitro. Human blood was dialyzed with minidialyzers (300-600 cm(2) membrane area) made of PS-ViE, cellulose, or untreated polusulfone (PS), and the effects of the dialyzers on complements (C3a, C4a, and C5a), cytokines (IL-1beta and IL-8), and granulocyte elastase as well as their anti-oxidative activity were investigated (n = 6). The effect of PS-ViE on complement activation and its effects on cytokines were comparable to those of PS membrane, whereas granulocyte elastase following dialysis with the PS-ViE membrane tended to be lower than that seen with PS membrane. The effects of PS-ViE-induced methemoglobin, lipid peroxide, and oxygen radicals were significantly less than those of PS membrane, indicating the antioxidative activity of PS-ViE. Vitamin E-modified polysulfone membrane dialyzers were found to have favorable effects on the immune system and to express antithrombotic and antioxidative effects.

Hollow-fiber blood-dialysis membranes: superoxide generation, permeation, and dismutation measured by chemiluminescence

The interaction of blood with a material surface results in activation of the body's humoral immune system and the generation of reactive oxygen species (ROS). It has recently become clear that ROS are central to the pathology of many diseases. In this study, we evaluated the superoxide generation, permeation, and dismutation in hollow-fiber dialysis membranes by using 2-methyl-6-p-methoxyphenylethynyl-imidazopyrazinone (MPEC) as a superoxide-reactive chemiluminescence producer and an optical fiber probe to detect the resulting chemiluminescence in the hollow fiber lumen. We measured the superoxide generated when bovine blood leukocytes were brought into contact with dialysis membranes. Superoxide permeation was determined by measuring MPEC chemiluminescence in the hollow fiber lumen using an optical fiber probe. Additionally, superoxide dismutation was evaluated by examining the difference in superoxide permeability for membranes with and without vitamin E coating. Superoxide generation varies for different membrane materials, depending on the membrane's biocompatibility. Superoxide permeability depends on the diffusive permeability of membranes. No marked decrease in superoxide permeability was observed among membrane materials. The superoxide permeability of vitamin E-coated membrane was smaller than that of uncoated membrane. The antioxidant property of vitamin E-coated membranes is hence effective in causing superoxide dismutation.

Relevance of Oxidative Pathways in the Pathophysiology of Chronic Kidney Disease

Patients with uremia (whether requiring renal replacement therapy or not) have a greatly increased cardiovascular risk that cannot be explained entirely by traditional cardiovascular risk factors. An increase in oxidative stress has been proposed as a nontraditional cardiovascular risk factor in this patient population. Using a wide variety of different biomarkers of increased oxidative stress status, numerous laboratories around the world have now unequivocally demonstrated that uremia is a state of increased oxidative stress. Recent data also suggest linkages between oxidative stress inflammation, endothelial dysfunction, and malnutrition in the uremic population. These factors are probably synergistic in their effects on atherogenecity and risk of a cardiovascular event. The pathophysiology of increased oxidative stress in uremia is multifactorial, but the retention of oxidized solute by the loss of kidney function is probably a major contributor. Uremic oxidative stress can be characterized biologically by an increase in lipid per oxidation products and reactive aldehyde groups as well as by increased retention of oxidized thiols. Two recently published studies have suggested that antioxidative therapy may be particularly promising in reducing cardiovascular events in this patient population.Further definitive studies of antioxidant use are greatly needed.

Cellulose, modified cellulose and synthetic membranes in the haemodialysis of patients with end-stage renal disease

BACKGROUND

When the kidney fails the blood-borne metabolites of protein breakdown and water cannot be excreted. The principle of haemodialysis is that such substances can be removed when blood is passed over a semipermeable membrane. Natural membrane materials include cellulose or modified cellulose, more recently various synthetic membranes have been developed. Synthetic membranes are regarded as being more "biocompatible" in that they incite less of an immune response than cellulose-based membranes.

OBJECTIVES

To assess the effects of different haemodialysis membrane material in patients with end-stage renal disease (ESRD).

SEARCH STRATEGY

We searched MEDLINE, EMBASE, PreMEDLINE, HealthStar CINAHL, the Cochrane Central Register of Controlled Trials (CENTRAL), Biosis, SIGLE, CRIB, UK National Research Register and reference lists of relevant articles. We contacted biomedical companies, known investigators and handsearched selected journals and conference proceedings. Date of most recent search: June 2004.

SELECTION CRITERIA

All randomised controlled trials (RCTs) or quasi-RCTs comparing different haemodialysis membrane material in patients with ESRD.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed the methodological quality of studies. Data was abstracted onto a standard form by one reviewer and checked by another. Relative Risk (RR) and weighted mean difference (WMD) with 95% confidence intervals (CI)) MAIN RESULTS: Thirty two studies were identified. Pre-dialysis ss(2) microglobulin concentrations were not significantly lower in patients treated with synthetic membranes (WMD -14.67, 95% CI -33.10 to 4.05). When analysed for change in ss(2) microglobulin, a fall was only noted with high-flux membranes. The incidence of amyloid was less in patients who were dialysed for six years with high-flux synthetic membranes (one study, RR 0.03, 95% CI 0.00 to 0.54). There was a significant difference in favour of the synthetic (high-flux) membrane in comparison to cellulose membranes for triglycerides (WMD -0.66; 95% CI -1.18 to -0.14) but not for modified cellulose membranes. Dialysis adequacy measured by Kt/V was marginally higher when cellulose membranes were used (WMD -0.10; 95% CI -0.16 to 0.04), whereas synthetic membranes achieved significantly higher Kt/V values when compared with modified cellulose membranes (WMD 0.20, 95% 0.11 to 0.29) . There were no data on quality of life measures.

AUTHORS' CONCLUSIONS

We found no evidence of benefit when synthetic membranes were compared with cellulose/modified cellulose membranes in terms of reduced mortality no reduction in dialysis-related adverse symptoms. Despite the relatively large number of RCTs undertaken in this area none of the included studies reported any measures of quality of life.