Does the extracorporeal circulation worsen anemia in hemodialysis patients? Investigation with advanced microscopes of red blood cells drawn at the beginning and end of dialysis

BACKGROUND

In hemodialysis (HD) patients, anemia relates to three main factors: insufficient production of erythropoietin; impaired management of iron; and decreased lifespan of red blood cells (RBCs). The third factor can relate to structural deterioration of RBCs due to extrinsic (extracorporeal circuit; biochemical activation and/or mechanical stress during dialysis) and intrinsic (uremic milieu; biochemical interference of the RBC membrane constituents with toxins) mechanisms. Herein, we evaluate information accessed with advanced imaging techniques at the cellular level.

METHODS

Atomic force and scanning electron microscopes were employed to survey intact RBCs (iRBCs) of seven HD patients in comparison to seven healthy donors. The extrinsic factor was investigated by contrasting pre- and post-HD samples. The intrinsic environment was investigated by comparing the microscopy data with the clinical ones.

RESULTS

The iRBC membranes of the enrolled HD patients were overpopulated with orifice-like (high incidence; typical size within 100-1,000 nm) and crevice-like (low incidence; typical size within 500-4,000 nm) defects that exhibited a statistically significant (P < 0.05) relative increase (+55% and +350%, respectively) in respect to healthy donors. The relative variation of the orifice and crevice indices (mean population of orifices and crevices per top membrane surface) between pre- and post-HD was not statistically significant (-3.3% and +4.5%, respectively). The orifice index correlates with the concentrations of urea, calcium, and phosphorus, but not, however, with that of creatinine.

CONCLUSION

Extracorporeal circulation is not detrimental to the structural integrity of RBC membranes. Uremic milieu is a candidate cause of RBC membrane deterioration, which possibly worsens anemia.

Serum hepcidin levels are associated with serum triglycerides and interleukin-6 concentrations in patients with end-stage renal disease

Hepcidin has emerged as a peptide with a key role in the regulation of iron homeostasis in patients with chronic kidney disease (CKD), having a strong dependence on inflammation. Recent studies reveal that hepcidin may be also associated with the progression of atherosclerosis. This study was performed to analyze the relation of hepcidin to markers of atherosclerosis and inflammation in patients on dialysis. A total of 90 individuals were enrolled. Sixty patients with end-stage renal disease, who were on hemodialysis (HD) (N = 30) and peritoneal dialysis (N = 30) were compared with 30 normal controls (NC). Age, body mass index, time on dialysis, serum lipids, C-reactive protein (CRP) and interleukin-6 (IL-6) were measured and analyzed in correlation with hepcidin concentration. It was found that patients on HD and peritoneal dialysis have significantly higher (P < 0.0001) levels of hepcidin, CRP and IL-6 than NC. Hepcidin in dialysis patients is significantly related to age (r = 0.373, P = 0.012), serum triglycerides (r = 0.401, P = 0.005), HDL-C (r = -0.268, P = 0.048), CRP (r = 0.436, P = 0.0007) and IL-6 (r = 0.569, P < 0.0001). In multiple regression analysis, hepcidin correlated independently with triglycerides (β = 0.402, P = 0.041) and IL-6 (β = 0.559, P = 0.006). Moreover, patients with high triglycerides in combination with high IL-6 levels have significantly increased concentrations of hepcidin than those with low triglycerides and low IL-6 levels (P < 0.0001). Elevated levels of hepcidin in patients with CKD on dialysis may be related to the occurrence of high triglycerides and high IL-6 serum concentrations. This probably suggests that hepcidin may play a role to the progression of atherosclerosis and inflammation, but this hypothesis should be further evaluated.

Novel biomarkers of acute kidney injury in the general adult ICU: a review

Acute kidney injury is one of the most frequent problems occurring in the critically ill patients of the intensive care units and it is well established that it increases both morbidity and mortality in these patients. Moreover, despite technological and pharmaceutical advances during the last decades, the incidence as well as the mortality associated with acute kidney injury in these patients remains unchanged. Creatinine, the most common renal dysfunction biomarker in use, has many disadvantages, such as time delay in its increase and the influence by other factors on its serum concentration, such as age, gender, muscle mass, etc. Hence, the need for better renal biomarkers in order to timely intervene for acute kidney injury prevention is imperative. The lack of an early biomarker is an obstacle for the development of new acute kidney injury prevention strategies. With the incidence of acute kidney injury reaching epidemic dimensions, the need for novel markers is urgent. During the last years, the research for finding such biomarkers has been intense. The purpose of the present article is to review the studies which have tested the predictive ability of those markers (in urine and/or plasma) for early detection of acute kidney injury in the mixed adult intensive care unit population and underline the potential limitations encountered in the various studies.

Antigen-specific apheresis of autoantibodies in myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disorder affecting the neuromuscular junction, usually caused by autoantibodies against the acetylcholine receptor (AChR) or the muscle-specific kinase (MuSK). Our aim is the development of a therapy based on the selective extracorporeal elimination of anti-AChR or anti-MuSK antibodies. To this end, the extracellular domains of the AChR subunits and MuSK have been expressed in yeast to be used as adsorbents, after optimization, and to obtain large quantities of proteins with near-native structure. We have characterized these proteins with respect to their use as specific immunoadsorbents for MG autoantibodies, and have begun large-scale experiments in order to verify the feasibility of application of the method for therapy. Furthermore, we have initiated animal studies to test possible toxicity and safety issues of the adsorbents or the procedure itself. The successful completion of the scale-up and safety tests will allow the initiation of clinical trials.

Defected red blood cell membranes and direct correlation with the uraemic milieu: the connection with the decreased red blood cell lifespan observed in haemodialysis patients

Together with impaired production of erythropoietin and iron deficiency, the decreased lifespan of red blood cells (RBCs) is a main factor contributing to the chronic anaemia observed in haemodialysis (HD) patients. Atomic force microscopy is employed in this work to thoroughly survey the membrane of intact RBCs (iRBCs) of HD patients in comparison to those of healthy donors, aiming to obtain direct information on the structural status of RBCs that can be related to their decreased lifespan. We observed that the iRBC membrane of the HD patients is overpopulated with extended circular defects, termed 'orifices', that have typical dimension ranging between 0.2 and 1.0 μm. The 'orifice' index-that is, the mean population of 'orifices' per top membrane surface-exhibits a pronounced relative increase of order 54 ± 12% for the HD patients as compared to healthy donors. Interestingly, for the HD patients, the 'orifice' index, which relates to the structural status of the RBC membrane, correlates strongly with urea concentration, which is a basic index of the uraemic milieu. Thus, these results indicate that the uraemic milieu downgrades the structural status of the RBC membrane, possibly triggering biochemical processes that result in their premature elimination from the circulation. This process could decrease the lifespan of RBCs, as observed in HD patients.

Intensification of peritoneal dialysis improves valacyclovir neurotoxicity

Valacyclovir induced neurotoxicity is a life-threatening complication, usually starting 24-48 h after drug-peak serum concentrations. The elderly with impaired renal function seem to be the most susceptible group to valacyclovir neurotoxicity. Although hemodialysis is considered the best method for rapid drug removal, our case showed that intensive peritoneal dialysis regimen leads to the recovery of neurotoxicity after 3 days.

Vascular access today

The number of patients with chronic kidney disease requiring renal replacement therapy has increased worldwide. The most common replacement therapy is hemodialysis (HD). Vascular access (VA) has a key role for successful treatment. Despite the advances that have taken place in the field of the HD procedure, few things have changed with regards to VA in recent years. Arteriovenous fistula (AVF), polytetrafluoroethylene graft and the cuffed double lumen silicone catheter are the most common used for VA. In the long term, a number of complications may present and more than one VA is needed during the HD life. The most common complications for all of VA types are thrombosis, bleeding and infection, the most common cause of morbidity in these patients. It has been estimated that VA dysfunction is responsible for 20% of all hospitalizations. The annual cost of placing and looking after dialysis VA in the United States exceeds 1 billion dollars per year. A good functional access is also vital in order to deliver adequate HD therapy. It seems that the native AVF that Brescia and Cimino described in 1966 still remains the first choice for VA. The native forearm AVFs have the longest survival and require the fewest interventions. For this reason, the forearm AVF is the first choice, followed by the upper-arm AVF, the arteriovenous graft and the cuffed central venous catheter is the final choice. In conclusion, VA remains the most important issue for patients on HD and despite the technical improvements, a number of problems and complications have to be resolved.

Successful non-surgical treatment of perirenal haematoma after percutaneous renal artery angioplasty in a solitary kidney

Renal artery angioplasty with stent placement represents an effective choice for correcting renal artery stenosis. However, if iatrogenic renal artery injury occurs, as in the case of solitary kidney, the risk of requiring chronic dialysis increases. This article reports the case of a patient with a solitary kidney, who underwent renal stenting and developed a retroperitoneal haematoma. The patient was managed conservatively and the perirenal haematoma resolved. Within the period of follow-up, the patient had maintained stable renal function with adequate blood pressure control.

Is there any association between IgA nephropathy, Crohn's disease and Helicobacter pylori infection?

A case of IgA nephropathy (IgAN) associated with Crohn's disease (CD) and preceded Helicobacter pylori (Hp) infection is described. Therapy with corticosteroids and azathioprine resulted in clinical improvement. The connection between IgAN and CD is well established, while tonsillar Hp is a potential antigen causative of IgAN. The three entities may reflect a common immunopathogenetic mechanism involving an IgA response to mucosal challenge.

Multiple histopathological skin alterations in a hemodialysis patient with severe pruritus

Pruritus is an alarming symptom in patients with end-stage renal disease (ESRD) accompanied by sleep disturbances and physical and mental disorders. Although its prevalence is very high among hemodialysis patients (90%), its etiology and its successful treatment have been unconfirmed (Melo N, Elias R, Castro M, Romao G, Abensur H. Pruritus in hemodialysis patients: The problem still remains. Hemodial Int. 2009;13:38-42.). Common pruritus etiologies, such as high parathyroid hormone levels, dialysis inadequacy, and iron deficiency are matters of conflict. The case of a hemodialysis patient with consistent itching and a variety of cutaneous eruptions, which after performing skin biopsy were explored and cured, is described. This article addresses the possibility of other causes of pruritus in ESRD and encourages watchful waiting with simple medical interventions, which would relieve patients' symptoms.

Erythrocyte Na+-Li+ counter-transport activity and digoxin-like substances in insulin dependent diabetic women with preexisting preeclampsia

AIM OF THE STUDY

To determine whether there is pathogenetic link between red cells sodium-lithium counter-transport activity and digoxin-like immunoreactive substances (DLIS) in plasma of insulin-dependent diabetic (IDDM) and non-diabetic women with preexisting preeclampsia (PE).

SUBJECTS AND METHODS

We studied Na(+)/Li(+) CT activity in red cells and plasma levels of DLIS in 11 IDDM women with preexisting PE (Group 1), 13 IDDM without preexisting PE (Group 2) 23 non-diabetic women with preexisting PE (Group 3) and 12 non-diabetic women with normal pregnancy (Group 4) at least 4 months after delivery.

RESULTS

Na(+)/Li(+) CT activity was higher in Group 1 compared to Group 2 (mean ± SEM 0.316 ± 0.05 vs 0.190 ± 0.02 mmol/LRBC/hr p < 0.05) and in Group 3 compared to Group 4 (0.365 ± 0.004 vs 0.168 ± 0.01 mmol/LRBC/hr, p < 0.01). Plasma levels of DLIS were higher in Group 3 compared to Group 4 (0.727 ± 0.189 vs 0.295 ± 0.066 ng/ml; p<0.05); there was no statistically significant difference between the two diabetic groups. In Groups 1 and 3, Na(+)/Li(+) CT activity was correlated to the plasma levels of DLIS (r = 0.927; p < 0.001 and r = 0.485; p<0.05 respectively).

CONCLUSION

Increased Na(+)/Li(+) CT activity and increased plasma levels of DLIS may contribute to PE in IDDM and non-diabetic women.

Is the underutilization of peritoneal dialysis in relation to hemodialysis, as renal replacement therapy, justifiable worldwide? Yes or No

Peritoneal dialysis is the most important home dialysis treatment for end stage renal diseases and needs personal involvement, and support from the family . Peritoneal dialysis presented a number of discouraging technical problems and led to the belief that PD was not an appropriate renal replacement therapy, for patients with end stage renal disease. Despite the improvement of the method its rate remain low (11%) worldwide. The factors affecting the choice of PD are multiple and explain the disparity in the use of peritoneal dialysis in different countries and different parts of the same country. Dialysis costs and reimbursement structures are significant in decisions about the rates and modalities of renal replacement therapy. Late referral and the health care system seems to be very important factors that influence the dialysis modality choice. After the initiation of peritoneal dialysis we can see other factors that influence the survival of the method. The rate of peritonitis and the peritoneum function seems to be important issues.

Correlation of depressive symptoms and olfactory dysfunction in patients on hemodialysis

BACKGROUND AND AIM

A possible link between depression and olfactory dysfunction has been suggested in the literature, in research projects using the olfactory bulbectomy model. In human studies using a syndrome-oriented approach, such an association has not been reported consistently. The aim of the study was to test the association of olfactory dysfunction with depression using a symptom-oriented approach.Paients and methods: Twenty eight end-stage renal failure patients took part in this project. The patients olfactory identification ability was tested with the University of Pennsylvania Smell Identification Test (UPSIT). Immediately before olfactory testing, the subjects completed the Zung self-rating scale, which provides data on symptoms of depression in this group of patients.

RESULTS

The mean value of the number of mistakes made in the olfactory identification ability (UPSIT test) by the total sample was 14.0±4.5, with a range 6-22. Half of the symptoms seem to bear an influence on the olfactory identification performance. Patients experiencing decreased libido and dissatisfaction exhibited significantly reduced olfactory function, as contrasted to those not experiencing these symptoms. The above results remain practically unaltered even after taking into account such probable confounding factors as age, sex, olfactory detection threshold and duration of illness.

CONCLUSION

These findings support previous evidence indicating that olfactory dysfunction may be related to specific depressive symptoms in humans. The present findings also suggest that the symptom-oriented approach is an effective research tool for the elucidation of such clinical issues. The need for further research in this field is pointed out.

Correlations of Sialic Acid with Markers of Inflammation, Atherosclerosis and Cardiovascular Events in Hemodialysis Patients

<i>Background:</i> Serum total sialic acid (S-TSA) is associated with atherosclerotic process in general population. The aim of our study was to evaluate possible correlations of S-TSA with markers of inflammation and atherosclerosis in hemodialysis (HD) patients. <i>Methods:</i> We involved 53 asymptomatic, nondiabetic HD patients and 28 healthy controls. Atherosclerosis was evaluated by carotid ultrasonography, estimating intima media wall thickness and wall to lumen ratio bilaterally. To confirm our findings, we performed a 32-month cohort study, during which cardiovascular (CV) events were analyzed in relation to S-TSA concentration. <i>Results:</i> HD patients had higher S-TSA compared to controls (adjusted OR: 1.04, p = 0.026). In HD patients, S-TSA independently correlated with hs-CRP (p < 0.0001), lipoprotein(a) (p = 0.02), intima media wall thickness (p = 0.023) and wall to lumen ratio (p = 0.028). Increased S-TSA concentration was associated with more CV events (p = 0.03). <i>Conclusions:</i> Serum TSA seems to correlate with inflammation, accelerated atherosclerosis and CV events in nondiabetic HD patients, but more studies need to confirm our findings.

Reactive Oxygen Metabolites: A Link between Oxidative Stress and Inflammation in Patients on Hemodialysis

Oxidative stress plays a significant role in the development of inflammation in patients undergoing hemodialysis (HD). This study intends to evaluate the relationship between C-reactive protein (CRP) and the newly established marker of lipid peroxidation, d-ROMs (reactive oxygen metabolites), in comparison with different indicators of oxidative stress. Plasma total antioxidant capacity (TAC), lipid peroxidation products malonaldehyde (MDA) and 4-hydroxyalkenals, as well as d-ROMs, were determined in 24 patients before HD and in 21 normal controls (NC). It was found that HD patients had higher levels of d-ROMs than NC (p = 0.033). A highly significant positive correlation was observed between logCRP and d-ROMs concentrations (p < 0.0001, r = 0.85) in patients, but not in NC. The concentrations of TAC and MDA were not associated with CRP in HD or in NC individuals. It is concluded that d-ROMs concentration is a potent marker of oxidative injury that is strongly indicative of the inflammatory status in HD patients.