Dementia in patients undergoing long-term dialysis: aetiology, differential diagnoses, epidemiology and management

Air Pollution: A Silent Key Driver of Dementia

In 2017, the Lancet Commission on Dementia Prevention, Intervention, and Care included air pollution in its list of potential risk factors for dementia; in 2018, the Lancet Commission on Pollution concluded that the evidence for a causal relationship between fine particulate matter (PM) and dementia is encouraging. However, few interventions exist to delay or prevent the onset of dementia. Air quality data are becoming increasingly available, and the science underlying the associated health effects is also evolving rapidly. Recent interest in this area has led to the publication of population-based cohort studies, but these studies have used different approaches to identify cases of dementia. The purpose of this article is to review recent evidence describing the association between exposure to air pollution and dementia with special emphasis on fine particulate matter of 2.5 microns or less. We also summarize here the proposed detailed mechanisms by which air pollutants reach the brain and activate the innate immune response. In addition, the article also provides a short overview of existing limitations in the treatment of dementia.

Effects of Subchronic Aluminum Exposure on Learning, Memory, and Neurotrophic Factors in Rats

Aluminum (Al) is a neurotoxin that gradually accumulates in the brain in human life, resulting in oxidative brain injury related to Alzheimer's disease (AD) and other diseases. In this study, the learning and memory of rats exposed to different aluminum concentrations (0.0 g/L, 2.0 g/L, 4.0 g/L, and 8.0 g/L) were studied, and the learning and memory of rats were observed by shuttle box experiment. With hematoxylin and eosin staining, Western blot, immunofluorescence, and RT-PCR, the morphology of nerve cells in the hippocampus of rat brain were observed, and the levels of activator protein-1 (AP-1) gene and protein, nerve growth factor (NGF), neurotrophin-3 (NT3), glial cell line-derived neurotrophic factor (GDNF), and brain-derived neurotrophic factor (BDNF) gene and protein level, etc. The experimental results showed that subchronic aluminum exposure damaged learning and memory in rats. The cognitive function damage in rats was more evident after increasing the aluminum intake dose. The more aluminum intake, the more pronounced the histological changes in the hippocampus will be. The expression level and protein content of neurotrophic factors in the hippocampus of rats showed a negative correlation with aluminum intake. In this experiment, we explored the mechanism of aluminum exposure in learning and memory disorders, and provided some data reference for further elucidation of the damage mechanism of aluminum on the nervous system and subsequent preventive measures.

Preclinical evidences of aluminum-induced neurotoxicity in hippocampus and pre-frontal cortex of rats exposed to low doses

Aluminum (Al) is a neurotoxicant agent implicated in several behavioral, neuropathological and neurochemical changes associated with cognitive impairments. Nevertheless, mechanisms of damage and safety concentrations are still very discussed. Thus, the main purpose of this study was to investigate whether two aluminum low doses were able to produce deleterious effects on cognition of adult rats, including oxidative stress in hippocampus and prefrontal cortex, two important areas for cognition. For this, thirty adult Wistar rats were divided into three groups: Al1 (8.3 mg/kg/day), Al2 (32 mg/kg/day) and Control (Ultrapure Water), in which all three groups received their solutions containing or not AlCl₃ by intragastric gavage for 60 days. After the experimental period, the short- and long-term memories were assessed by the object recognition test and step-down inhibitory avoidance. After euthanizing, prefrontal cortex and hippocampus samples were dissected for Al levels measurement and evaluation of oxidative biochemistry. Only Al2 increased Al levels in hippocampal parenchyma significantly; both concentrations did not impair short-term memory, while long-term memory was affected in Al1 and Al2. In addition, oxidative stress was observed in prefrontal and hippocampus in Al1 and Al2. Our results indicate that, in a translational perspective, humans are subjected to deleterious effects of Al over cognition even when exposed to low concentrations, by triggering oxidative stress and poor long-term memory performance.

The Possible Neuroprotective Effect of Silymarin against Aluminum Chloride-Prompted Alzheimer's-Like Disease in Rats

Alzheimer's disease (AD) is a worldwide rapidly growing neurodegenerative disease. Here, we elucidated the neuroprotective effects of silymarin (SM) on the hippocampal tissues of aluminum chloride (AlCl3)-induced Alzheimer-like disease in rats using biochemical, histological, and ultrastructural approaches. Forty rats were divided into control, SM, AlCl3, and AlCl3 + SM groups. Biochemically, AlCl3 administration resulted in marked elevation in levels of lipid peroxidation (LPO) and nitric oxide (NO) and decrease in levels of reduced glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD). Moreover, AlCl3 significantly increased tumor necrosis factor-α (TNF-α), interleukin-1beta (IL-1β), and acetylcholinesterase (AChE) activities. Furthermore, myriad histological and ultrastructural alterations were recorded in the hippocampal tissues of AlCl3-treated rats represented as marked degenerative changes of pyramidal neurons, astrocytes, and oligodendrocytes. Additionally, some myelinated nerve fibers exhibited irregular arrangement of their myelin coats, while the others revealed focal degranulation of their myelin sheaths. Severe defects in the blood-brain barrier (BBB) were also recorded. However, co-administration of SM with AlCl3 reversed most of the biochemical, histological, and ultrastructural changes triggered by AlCl3 in rats. The results of the current study indicate that SM can potentially mend most of the previously evoked neuronal damage in the hippocampal tissues of AlCl3-kindled rats.

The concurrent exposure to aluminium and fructose induces liver injury in rats: Protection by monoammonium glycyrrhizinate

Aluminium is a ubiquitous element that occurs naturally in the soil making human exposure to it unavoidable. It is implicated in the aetiology of different neurodegenerative diseases and can induce liver injury. In addition, insulin resistance (IR) plays an essential role in the pathogenesis and the progression of liver disorders. The increased consumption of fructose contained in soft drinks and western pattern diet results in IR that along with the wide distribution of aluminium make the concurrent exposure conceivable and increase the risk of liver injury. Therefore, the present study explores the hepatotoxic effects of aluminium and fructose administered concurrently and evaluates the possible protection by monoammonium glycyrrhizinate (MAG). Liver injury was induced by the administration of aluminium chloride (34 mg/kg/d) plus 10% (w/v) fructose in drinking water. Male rats were treated with either MAG (40 mg/kg/d) or silymarin (SIL, 100 mg/kg/d). The concurrent administration of aluminium and fructose (FRUAL) induced liver injury manifested as a significant elevation of serum liver enzymes activities, bilirubin level, and prothrombin time, as well as reduction of albumin level. On the other hand, the administration of MAG improved the FRUAL-induced aberrations of liver function tests and hepatic cytoarchitecture. We assume that the MAG-induced suppression of oxidative stress, toll-like receptor 4 pathway activation, inflammation, and apoptosis might play a crucial role in the hepatoprotective effect of MAG in this model. Intriguingly, the hepatoprotective effect MAG against FRUAL-induced liver injury surpasses that of the gold standard SIL, suggesting MAG as a better alternative to SIL.

Controversies in the Management of Secondary Hyperparathyroidism in Chronic Kidney Disease

Secondary hyperparathyroidism is a frequent complication of chronic kidney disease that begins early in the course of renal insufficiency as an adaptive response to maintain mineral homeostasis. This complex disorder affects the bone, leading to an increase in fracture risk and is associated with increased risks of vascular calcification and mortality. PURPOSE OF REVIEW: In this review, we examine the different strategies available to manage secondary hyperparathyroidism. Particularly, we focus on the adequate control of serum phosphorus by restricting intake and the use of phosphate binders, correction of hypocalcemia while minimizing calcium burden, and reduction in PTH levels through the use of vitamin D sterols and calcimimetics. RECENT FINDINGS: It was observed that although numerous agents directed at the correction of these abnormalities have demonstrated effectiveness on biochemical markers, there is still a relative scarcity of studies demonstrating treatment effectiveness as measured by hard clinical outcomes. In addition, most agents have side effects that may limit their use, even in patients in which the treatment has demonstrated efficacy in controlling these parameters. There is still controversy as to what therapeutic regimens to choose for a particular patient and what parameter should be used to follow their effects, including outcomes, side effects, pill burden, and costs, among others. In the present article, we analyze controversial aspects of the different therapeutic agents available. Although many tools and regimens are available, no one by itself is enough for an adequate management of the patient. But rather, combined therapy and individualization of approaches are recommended for better results. We suggest that new studies analyzing the effectiveness of therapeutic approaches to the management of secondary hyperparathyroidism should be directed not only to controlling parathyroid hormone levels but also to the evaluation of long-term outcomes, based on modification of morbidity, mortality, and end organ impact, while reducing side effects and controlling costs, among others.

Metal Ions in Alzheimer's Disease: A Key Role or Not?

Despite tremendous research efforts in universities and pharmaceutical companies, effective drugs are still lacking for the treatment of Alzheimer's disease (AD). The biochemical mechanisms of this devastating neurodegenerative disease have not yet been clearly understood. Besides a small percentage of cases with early onset disease having a genetic origin (<5%, familial AD), most cases develop in the elderly as a sporadic form due to multiple and complex parameters of aging. Consequently, AD is spreading in all countries with a long life expectancy. AD is characterized by deposition of senile plaques made of β-amyloid proteins (Aβ) and by hyperphosphorylation of tau proteins, which have been considered as the main drug targets up to now. However, antibodies targeting amyloid aggregates, as well as enzyme inhibitors aiming to modify the amyloid precursor protein processing, have failed to improve cognition in clinical trials. Thus, to set up effective drugs, it is urgent to enlarge the panel of drug targets. Evidence of the link between AD and redox metal dysregulation has also been supported by post-mortem analyses of amyloid plaques, which revealed accumulation of copper, iron, and zinc by 5.7, 2.8, and 3.1 times, respectively, the levels observed in normal brains. Copper-amyloid complexes, in the presence of endogenous reductants, are able to catalyze the reduction of dioxygen and to produce reduced, reactive oxygen species (ROS), leading to neuron death. The possibility of using metal chelators to regenerate normal trafficking of metal ions has been considered as a promising strategy in order to reduce the redox stress lethal for neurons. However, most attempts to use metal chelators as therapeutic agents have been limited to existing molecules available from the shelves. Very few chelators have resulted from a rational design aiming to create drugs with a safety profile and able to cross the blood-brain barrier after an oral administration. In the human body, metals are handled by a sophisticated protein network to strictly control their transport and reactivity. Abnormal concentrations of certain metals may lead to pathological events due to misaccumulation and irregular reactivity. Consequently, therapeutic attempts to restore metal homeostasis should carefully take into account the coordination chemistry specificities of the concerned redox-active metal ions. This Account is focused on the role of the main biologically redox-active transition metals, iron and copper. For iron, the recent debate on the possible role of magnetite in AD pathogenesis is presented. The section devoted to copper is focused on the design of specific copper chelators as drug candidates able to regulate copper homeostasis and to reduce the oxidative damage responsible for the neuron death observed in AD brains. A short survey on non-redox-active metal ions is also included at the beginning, such as aluminum and its controversial role in AD and zinc which is a key metal ion in the brain.

Increased urinary excretion of aluminium after ingestion of the food additive sodium aluminium phosphate (SALP) - a study on healthy volunteers

Food is an important source of human aluminium (Al) exposure and regular consumption of foods containing Al-based food additives may result in high Al intakes above health-based tolerable intakes. However, some additives are Al salts with low solubility, and little is known about bioavailability of Al in these additives. We investigated urine Al concentrations in healthy adult volunteers (N = 18, women/men) before (base-line) and after 7 days of ingestion of pancakes with a low Al content (median: <0.5 mg Al/kg) and high Al content (median: 860 mg/kg). The high-Al pancakes contained the common additive sodium aluminium phosphate (SALP). The participants did not know if the pancakes contained SALP or not during the experiment. After adjusting for creatinine content of the urine samples, median base-line Al concentrations before pancake ingestion were in the range 30-40 µmol Al/mol creatinine. Urine Al concentrations after ingestion of low-Al pancakes (average intake: <0.042 Al mg/day) did not differ significantly from the base-line levels. After ingestion of high-Al pancakes (72 mg Al/day) the median Al concentration in urine was more than 2-fold higher than at the base-line sampling before the high-Al pancake ingestion. At the end of the experiment the volunteers ingested an Al-containing antacid (Al-OH, 1800 mg Al/day) for 7 days as a positive control of Al absorption. This caused a 10-fold increase in median urine Al concentration compared to base-line. Our results strongly suggest that Al in the form of SALP in a pancake mix is bioavailable for absorption in humans, which should be taken into account in risk assessment of Al in food in countries with a high use of SALP as a food additive.

Human health risk associated with the management of phosphorus in freshwaters using lanthanum and aluminium

The use of geo-engineering materials to manage phosphorus in lakes has increased in recent years with aluminium and lanthanum based materials being most commonly applied. Hence the potential impact of the use of these compounds on human health is receiving growing interest. This review seeks to understand, evaluate and compare potential unintended consequences on human health and ecotoxicological risks associated with the use of lanthanum- and aluminium-based materials to modify chemical and ecological conditions in water bodies. In addition to their therapeutic use for the reduction of intestinal phosphate absorption in patients with impaired renal function, the phosphate binding capacity of aluminium and lanthanum also led to the development of materials used for water treatment. Although lanthanum and aluminium share physicochemical similarities and have many common applications, their uptake and kinetics within the human body and living organisms importantly differ from each other which is reflected in a different toxicity profile. Whilst a causal role in the development of neurological pathologies, skeletal lesions, hematopoietic disorders and respiratory effects has unequivocally been demonstrated with increased exposure to aluminium, studies until now have failed to find such a clear association after exposure to lanthanum although caution is warranted. Our review indicates that lanthanum and aluminium have a distinctly different profile with respect to their potential effects on human health. Regular monitoring of both aluminium and lanthanum concentrations in lanthanum-/aluminium-treated water by the responsible authorities is recommended to avoid acute accidental or chronic low level accumulation.

Association of Serum Aluminum Levels with Mortality in Patients on Chronic Hemodialysis

Despite reported evidence on the relationship between higher serum aluminum levels and poor outcomes in patients on chronic hemodialysis (CHD), the acceptable cutoff value of serum aluminum for mortality remains unclear. A retrospective observational cohort study with 636 Taiwanese patients on CHD was conducted to investigate the impact of serum aluminum levels on mortality. The predictors were bivariate serum aluminum level (<6 and ≥6 ng/mL) and the Outcomes were all-cause and cardiovascular (CV) mortality. During the mean follow-up of 5.3 ± 2.9 years, 253 all-cause and 173 CV deaths occurred. Crude analysis showed that a serum aluminum level of ≥6 ng/mL was a significant predictor of all-cause [hazard ratio (HR), 1.80; 95% confidence interval (CI), 1.40–2.23] and CV (HR, 1.84; 95% CI, 1.36–2.50) mortality. After multivariable adjustment, the serum aluminum level of ≥6 ng/mL remained a significant predictor of all-cause mortality (HR, 1.37, 95% CI, 1.05–1.81) but became insignificant for CV mortality (HR, 1.29; 95% CI, 0.92–1.81). Therefore, our study revealed that a serum aluminum level of ≥6 ng/mL was independently associated with all-cause death in patients on CHD, suggesting that early intervention for aluminum level in patients on CHD might be beneficial even in the absence of overt aluminum toxicity.

Association between serum aluminum levels and cardiothoracic ratio in patients on chronic hemodialysis

The cardiothoracic ratio (CTR) and serum aluminum levels are both associated with mortality in hemodialysis patients. However, limited data regarding the association between serum aluminum levels and the CTR have been published to date. Therefore, we aimed to elucidate this association in patients on chronic hemodialysis (CHD). We investigated the association between the serum aluminum level and the CTR in CHD in a retrospective cross-sectional study of 547 Taiwanese patients on CHD. The mean age of patients was 62.5±13.2 years, with a mean hemodialysis time of 7.1±5.2 years. Among the patients, 36.9% were diabetic and 47.9% were male. After natural logarithmic transformation (ln(aluminum)), the serum aluminum level exhibited an independent and linear relationship with the CTR (β: 1.40, 95% confidence interval (CI), 0.6–2.2). A high serum aluminum level (≥6 ng/dL) was significantly associated with a CTR >0.5 in the crude analysis (odds ratio (OR): 2.15, 95% CI, 1.52–3.04) and remained significant after multivariable adjustment (OR: 2.45, 95% CI, 1.63–3.67). Moreover, the ln(aluminum) value was significantly associated with a CTR >0.5 (OR: 1.71, 95%CI, 1.28–2.29) in multivariable analysis, indicating a dose effect of aluminum on cardiomegaly. In conclusion, the serum aluminum level was independently associated with cardiac remodeling (elevated CTR) in patients on CHD.

Association of low serum aluminum level with mortality in hemodialysis patients

Background

The National Kidney Foundation–Kidney Disease Outcomes Quality Initiative recommends that the serum aluminum level (SAL) should be below 20 µg/L for patients with maintenance hemodialysis (MHD). However, serum aluminum may have toxic effects on MHD patients even when it is in the apparently acceptable range (below 20 µg/L).

Methods

The Medical Ethics Committee approved this study. Initially, 954 MHD patients in dialysis centers were recruited. A total of 901 patients met the inclusion criteria and were followed-up for 1 year. Patients were stratified by SAL into four equal-sized groups: first quartile (<6 µg/L), second quartile (6–9 µg/L), third quartile (9–13 µg/L), and fourth quartile (>13 µg/L). Demographic, biochemical, and dialysis-related data were obtained for analyses. A linear regression model was applied to identify factors associated with SAL. Cox proportional hazard model was used to determine the significance of variables in prediction of mortality.

Results

Only 9.3% of MHD patients had SALs of 20 µg/L or more. At the end of the follow-up, 54 patients (6%) died, and the main cause of death was cardiovascular disease. Kaplan–Meier survival analysis showed that patients in the fourth SAL quartile had higher mortality than those in the first SAL quartile (log rank test, χ²=13.47, P=0.004). Using the first quartile as reference, Cox multivariate analysis indicated that patients in the third quartile (hazard ratio =1.31, 95% confidence interval =1.12–1.53, P=0.038) and the fourth quartile (hazard ratio =3.19, 95% confidence interval =1.08–8.62, P=0.048) had increased risk of all-cause mortality.

Conclusion

This study demonstrates that SAL, even when in an apparently acceptable range (below 20 µg/L), is associated with increased mortality in MHD patients. The findings suggest that avoiding exposure of aluminum as much as possible is warranted for MHD patients.

Serum aluminum levels in dialysis patients after sclerotherapy of internal hemorrhoids with aluminum potassium sulfate and tannic acid

PURPOSE

Aluminum potassium sulfate and tannic acid (ALTA) is an effective sclerosing agent for internal hemorrhoids. However, it is contraindicated for patients with chronic renal failure on dialysis, because the aluminum in ALTA can cause aluminum encephalopathy when it is not excreted effectively. We conducted this study to measure the serum aluminum concentrations and observe for symptoms relating to aluminum encephalopathy in dialysis patients after ALTA therapy.

METHODS

Ten dialysis patients underwent ALTA therapy for hemorrhoids. We measured their serum aluminum concentrations and observed them for possible symptoms of aluminum encephalopathy.

RESULTS

The total injection volume of ALTA solution was 31 mL (24-37). The median serum aluminum concentration before ALTA therapy was 9 μg/L, which increased to 741, 377, and 103 μg/L, respectively, 1 h, 1 day, and 1 week after ALTA therapy. These levels decreased rapidly, to 33 μg/L by 1 month and 11 μg/L by 3 months after ALTA therapy. No patient suffered symptoms related to aluminum encephalopathy.

CONCLUSIONS

Although the aluminum concentrations increased temporarily after ALTA therapy, dialysis patients with levels below 150 μg/L by 1 week and thereafter are considered to be at low risk of the development of aluminum encephalopathy.

Pro-apoptotic effect of methylguanidine on hydrogen peroxide-treated rat glioma cell line

Guanidino compounds, as methylguanidine (MG), may play an important role in the etiology of neurological complications which occur in uremic syndrome. Dementia is a neurological complication more common in uremic patients than in general population and several types of dementia are associated to astroglial apoptosis. Here we report the effect of MG on oxidative stress-induced apoptosis in rat glioma cell line (C6) in vitro. The oxidative stress was induced by hydrogen peroxide (H(2)O(2); 1 mM) and the cellular and molecular parameters were observed after 18 h. Uremic conditions were simulated by pre-incubation of C6 cells with MG (0.1-10 mM) 1h before H(2)O(2)-induced oxidative stress. MG alone did not affect cell viability, but it significantly increased cell death induced by H(2)O(2), as assessed by MTT assay. This effect could be related to the MG capability to enhance H(2)O(2) pro-apoptotic effect on C6 cells. The fluorescent dye FURA 2-AM test showed a significant raise in [Ca(2+)](i) in MG and H(2)O(2) co-treated C6 cells, mainly for depolarizing mitochondrial membrane potential. Furthermore, MG in a concentration-dependent manner, significantly increased H(2)O(2)-induced Bax expression, activation of caspase-3 and PARP in C6 cells. This study firstly reports that the uremic catabolyte MG could contribute to neurodegeneration associated to uremia enhancing the pro-apoptotic effect of H(2)O(2) and through an alteration in mitochondrial calcium homeostasis in glial cells.

Effects of chronic aluminum exposure on memory through multiple signal transduction pathways

OBJECTIVE

To investigate the effects of chronic aluminum (Al) exposure on memory of rats by recording long-term potentiation (LTP) induction in CA1 region of Schaffer collateral (SC) of hippocampus and observing the changes of key LTP induction-related kinases.

METHODS

Forty weaned Wistar rats were divided into 4 groups ad libitum, each group 10 rats. Three groups were fed with 0.2%, 0.4% and 0.6% AlCl(3) in drinking water for three months individually to set up the aluminum exposure models and the rest group was the control. After behavioral test, electrophysiological recordings were made at area CA1 from hippocampal SC branch followed by biochemical examination for several key kinases involved in LTP induction and formation.

RESULTS

Chronic exposure of Al significantly decrease the activities of protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) and reduced the expression levels of extracellular signal-regulated kinases (ERK1/2) and Ca(2+)-calmodulin dependent protein kinase II (CaMKII) in hippocampus, attenuating the population spike (PS) amplitude of LTP from the hippocampal CA1 region, causing impaired memory abilities of rats.

CONCLUSIONS

Aluminum accumulation in the hippocampus affects several crucial kinases involved in LTP induction and formation, resulting in impairment of memory.

Microemboli, developed during haemodialysis, pass the lung barrier and may cause ischaemic lesions in organs such as the brain

BACKGROUND

Chronic haemodialysis (HD) may relieve some medical problems of terminal uraemia, but the life expectancy of patients is still significantly shortened, and there is a greatly increased morbidity. This includes pulmonary morbidity and chronic central nervous system (CNS) abnormalities. Previous studies have shown that a considerable amount of air microbubbles emanate within the blood lines of the dialysis device and pass the air detector without sounding an alarm. The aim of this study was to investigate whether microemboli can pass to the patient and whether they could be detected in the carotid artery.

METHODS

A total of 54 patients on chronic HD (16 with central dialysis catheter) were investigated with an ultrasound detector (Hatteland, Røyken, Norway) for the presence of microemboli at the arteriovenous (AV) fistula/graft and at the common carotid artery before and during HD. Measurements were taken for 2 and 5 min, respectively. Non-parametric paired statistics were used (Wilcoxon).

RESULTS

The median number (range) and mean +/- SD of microembolic signals detected at the AV access site before commencing dialysis and during HD were 0 (0-3) and 0.2+/- 0.5 versus 4 (0-85) and 13.5 +/- 20 (P = 0.000); at the carotid artery, 1 (0-14) and 1.7 +/- 2.9 versus 2 (0-36) and 3.5 +/- 5.8 (P = 0.008).

CONCLUSIONS

The infused and returning fluid from HD devices contains air microbubbles that enter the patient without triggering any alarms. These small emboli pass the lung and may cause ischaemic lesions in organs supported by the arterial circuit, such as the brain.

A new paradigm for the treatment of secondary hyperparathyroidism

The global rise in chronic kidney disease makes secondary hyperparathyroidism (SHPT) a growing medical concern. Conventional therapies for treating SHPT are limited and include calcium-based and calcium-free phosphate binders for reducing serum phosphorus and vitamin D or its analogues for simultaneous stimulation of calcium absorption and suppression of parathyroid hormone (PTH) gene expression. Control of SHPT using these therapies has typically been poor. Recent studies have demonstrated that use of calcimimetics that reduce PTH secretion by increasing the sensitivity of the parathyroid gland calcium-sensing receptor to circulating calcium allow improved control of serum PTH, calcium, phosphorus and calcium-phosphorus product. This review describes experimental data and the clinical rationale supporting novel strategies for the integration of calcimimetics with conventional therapies to improve control of SHPT.

La population âgée hémodialysée : évaluer et prendre en charge le risque de déclin cognitif

Epidemiological data suggest a large prevalence of cognitive impairment in elderly patients on haemodialysis. They are frequently exposed to pathologies that affect the brain, and hold a plurality of risk factors for neurodegenerative and vascular dementia. Cognitive dysfunctions, because of their medical and socio-economical consequences, may led to discuss the indication for haemodialysis and its profit for the elderly patient. These facts highlight the advantage of a regular assessment of cognitive functions in this population. They also suggest the need in the future of a multidisciplinary intervention for these patients, for a better evaluation of interventions aimed on primary and secondary prevention of cognitive decline in the elderly group.

Efficacy, Tolerability, and Safety of Lanthanum Carbonate in Hyperphosphatemia: A 6-Month, Randomized, Comparative Trial versus Calcium Carbonate

BACKGROUND/AIMS

Hyperphosphatemia is an important clinical consequence of renal failure, and its multiple adverse systemic effects are associated with significantly increased risks of morbidity and mortality in dialysis patients. Existing oral phosphate binders have not permitted control of serum phosphate within currently accepted guidelines. This study compares lanthanum carbonate with calcium carbonate for control of serum phosphate in hemodialysis patients.

METHODS

In this European multicentre study, 800 patients were randomised to receive either lanthanum or calcium carbonate and the dose titrated over 5 weeks to achieve control of serum phosphate. Serum levels of phosphate, calcium and parathryoid hormone were followed over the following 20 weeks.

RESULTS

Around 65% of patients in each group achieved phosphate control, but in the calcium carbonate group this was at the expense of significant hypercalcemia (20.2% of patients vs. 0.4%). Consequently, calcium x phosphate product tended to be better controlled in the lanthanum group.

CONCLUSION

This 6-month study demonstrates that serum phosphate control with lanthanum carbonate (750-3,000 mg/day) is similar to that seen with calcium carbonate (1,500-9,000 mg/day), but with a significantly reduced incidence of hypercalcemia. Lanthanum carbonate is well tolerated and may be more effective in reducing calcium x phosphate product than calcium carbonate.

Neurological complications in renal failure: a review

Neurological complications whether due to the uremic state or its treatment, contribute largely to the morbidity and mortality in patients with renal failure. Despite continuous therapeutic advances, many neurological complications of uremia, like uremic encephalopathy, atherosclerosis, neuropathy and myopathy fail to fully respond to dialysis. Moreover, dialytic therapy or kidney transplantation may even induce neurological complications. Dialysis can directly or indirectly be associated with dialysis dementia, dysequilibrium syndrome, aggravation of atherosclerosis, cerebrovascular accidents due to ultrafiltration-related arterial hypotension, hypertensive encephalopathy, Wernicke's encephalopathy, hemorrhagic stroke, subdural hematoma, osmotic myelinolysis, opportunistic infections, intracranial hypertension and mononeuropathy. Renal transplantation itself can give rise to acute femoral neuropathy, rejection encephalopathy and neuropathy in graft versus host disease. The use of immunosuppressive drugs after renal transplantation can cause encephalopathy, movement disorders, opportunistic infections, neoplasms, myopathy and progression of atherosclerosis. We address the clinical, pathophysiological and therapeutical aspects of both central and peripheral nervous system complications in uremia.

Aluminum accumulation and membrane fluidity alteration in synaptosomes isolated from rat brain cortex following aluminum ingestion: effect of cholesterol

In the present work, we studied the effect of cholesterol/phospholipid (CH/PL) molar ratio on aluminum accumulation and aluminum-induced alteration of membrane fluidity in rat brain cortex synaptosomes. We observed that sub-acute (daily supply of 1.00 g of AlCl(3) during 10 days) and chronic (daily supply of 0.03 g of AlCl(3) during 4 months) exposure to dietary aluminum leads to a synaptosomal aluminum enrichment of 45 and 59%, respectively. During chronic exposure to AlCl(3), the enhancement of aluminum content was prevented by administration of colestipol (0.31 g/day), which decreased the synaptosomal membrane CH/PL molar ratio (nmol/nmol) from 1.2 to 0.4. Fluorescence anisotropy analysis, using 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-(4-(trimethylamino)phenyl)-6-phenylhexa-1,3,5-triene (TMA-DPH), showed that after treatment with colestipol a decrease in membrane order occurs at the level of hydrophilic lipid-water surface and deeper hydrophobic region of the synaptosomal membrane. When the rats were exposed to aluminum, it was observed a significant enhancement of membrane fluidity, which was more pronounced at the level of the membrane hydrophilic regions. Meanwhile, when chronic exposure to dietary AlCl(3) was accompanied by treatment with colestipol, the aluminum-induced decrease in membrane order was negligible when compared to TMA-DPH and DPH anisotropy values measured upon colestipol treatment. In contrast, in vitro incubation of synaptosomes (isolated from control rats) with AlCl(3) induced a concentration-dependent rigidification of this more hydrophilic membrane region. The opposite action of aluminum on synaptosomal membrane fluidity, during in vivo and in vitro experiments, appears to be explained by alteration of synaptosomal CH/PL molar ratio, since a significant reduction (approximately 80%) of this parameter occurs during in vivo exposure to aluminum. In conclusion, during in vivo exposure to aluminum, fluidification of hydrophilic regions and reduction of CH/PL molar ratio of presynaptic membranes accompany the accumulation of this cation, which appear to restrict aluminum retention in brain cortex nerve terminals.