Iron Rims in Patients With Multiple Sclerosis as Neurodegenerative Marker? A 7-Tesla Magnetic Resonance Study.

Introduction: Multiple sclerosis (MS) is a demyelinating and neurodegenerative disease of the central nervous system, characterized by inflammatory-driven demyelination. Symptoms in MS manifest as both physical and neuropsychological deficits. With time, inflammation is accompanied by neurodegeneration, indicated by brain volume loss on an MRI. Here, we combined clinical, imaging, and serum biomarkers in patients with iron rim lesions (IRLs), which lead to severe tissue destruction and thus contribute to the accumulation of clinical disability. Objectives: Subcortical atrophy and ventricular enlargement using an automatic segmentation pipeline for 7 Tesla (T) MRI, serum neurofilament light chain (sNfL) levels, and neuropsychological performance in patients with MS with IRLs and non-IRLs were assessed. Methods: In total 29 patients with MS [15 women, 24 relapsing-remitting multiple sclerosis (RRMS), and five secondary-progressive multiple sclerosis (SPMS)] aged 38 (22-69) years with an Expanded Disability Status Score of 2 (0-8) and a disease duration of 11 (5-40) years underwent neurological and neuropsychological examinations. Volumes of lesions, subcortical structures, and lateral ventricles on 7-T MRI (SWI, FLAIR, and MP2RAGE, 3D Segmentation Software) and sNfL concentrations using the Simoa SR-X Analyzer in IRL and non-IRL patients were assessed. Results: (1) Iron rim lesions patients had a higher FLAIR lesion count (p = 0.047). Patients with higher MP2Rage lesion volume exhibited more IRLs (p <0.014) and showed poorer performance in the information processing speed tested within 1 year using the Symbol Digit Modalities Test (SDMT) (p <0.047). (2) Within 3 years, patients showed atrophy of the thalamus (p = 0.021) and putamen (p = 0.043) and enlargement of the lateral ventricles (p = 0.012). At baseline and after 3 years, thalamic volumes were lower in IRLs than in non-IRL patients (p = 0.045). (3) At baseline, IRL patients had higher sNfL concentrations (p = 0.028). Higher sNfL concentrations were associated with poorer SDMT (p = 0.004), regardless of IRL presence. (4) IRL and non-IRL patients showed no significant difference in the neuropsychological performance within 1 year. Conclusions: Compared with non-IRL patients, IRL patients had higher FLAIR lesion counts, smaller thalamic volumes, and higher sNfL concentrations. Our pilot study combines IRL and sNfL, two biomarkers considered indicative for neurodegenerative processes. Our preliminary data underscore the reported destructive nature of IRLs.

Current-Controlled Spin Precession of Quasistationary Electrons in a Cubic Spin-Orbit Field.

Space- and time-resolved measurements of spin drift and diffusion are performed on a GaAs-hosted two-dimensional electron gas. For spins where forward drift is compensated by backward diffusion, we find a precession frequency in the absence of an external magnetic field. The frequency depends linearly on the drift velocity and is explained by the cubic Dresselhaus spin-orbit interaction, for which drift leads to a spin precession angle twice that of spins that diffuse the same distance.

Osteoclasts on bone and dentin in vitro: mechanism of trail formation and comparison of resorption behavior.

The main function of osteoclasts in vivo is the resorption of bone matrix, leaving behind typical resorption traces consisting of pits and trails. The mechanism of pit formation is well described, but less is known about trail formation. Pit-forming osteoclasts possess round actin rings. In this study we show that trail-forming osteoclasts have crescent-shaped actin rings and provide a model that describes the detailed mechanism. To generate a trail, the actin ring of the resorption organelle attaches with one side outside the existing trail margin. The other side of the ring attaches to the wall inside the trail, thus sealing that narrow part to be resorbed next (3­21 lm). This 3D configuration allows vertical resorption layer-by-layer from the surface to a depth in combination with horizontal cell movement. Thus, trails are not just traces of a horizontal translation of osteoclasts during resorption. Additionally, we compared osteoclastic resorption on bone and dentin since the latter is the most frequently used in vitro model and data are extrapolated to bone. Histomorphometric analyses revealed a material-dependent effect reflected by an 11-fold higher resorption area and a sevenfold higher number of pits per square centimeter on dentin compared to bone. An important material-independent aspect was reflected by comparable mean pit area (µm²) and podosome patterns. Hence, dentin promotes the generation of resorbing osteoclasts, but once resorption has started, it proceeds independently of material properties. Thus, dentin is a suitable model substrate for data acquisition as long as osteoclast generation is not part of the analyses.

High levels of lung resident CD4+CD28null cells in COPD: implications of autoimmunity.

Chronic obstructive pulmonary disease (COPD) is a worldwide burden and a major cause of death. Pathogenetic mechanisms underlying the disease are still largely unknown. However, a continuous toxic injury due to tobacco smoking leading to a self-maintaining inflammatory process is considered a key factor in the pathophysiology of the disease. Evidence that autoimmunity might be involved in the maintenance of COPD has been recently noticed with great interest.During the chronic phase of an autoimmune response, lymphocytes lose their costimulatory signals. Previously, CD4+CD28null cells were reported to be systemically heightened in COPD patients. However, a direct role of CD4+CD28null cells in the pathogenesis of COPD is still under discussion, since there is no evidence that CD4+CD28null cells originate from the lungs of diseased patients. Therefore, we evaluated lungs from end-stage COPD patients and compared the levels of tissue infiltrating CD4+CD28null cells to systemic levels. We could show that CD4+CD28null cells are present in high amounts in lung tissue obtained from COPD GOLD IV patients suggesting a direct involvement of those cells in the pathophysiology of COPD. Furthermore, purified lung-resident CD4+ cells showed a stable proliferative response to lung specific elastin and collagen.These results further corroborate the role of autoreactive CD4+ cells in the maintenance of the inflammatory destruction in COPD. Modulating CD4+ cell function might be a new promising tool for future therapeutic approaches.

Internal carotid artery surgery in regional anesthesia at the Clinic of Surgery in Pilsen during the past 5 years.

A low percentage of perioperative complications and excellent long-term outcome following carotid artery surgery in Vascular Centers demonstrate the priority of surgical solutions in patients with significant findings on carotid arteries, in the prevention and treatment of ischemic cerebrovascular accidents. The group of patients from the Clinic of Surgery in Pilsen demonstrates the benefits of regional anesthesia during internal carotid artery surgery, both in terms of the patients' health and the financial costs incurred by the hospital.

[Severe injury to the chest wall--experience with surgical therapy]. / Schwerwiegende Brustkorbverletzungen - Erfahrungen mit der operativen Behandlung.

INTRODUCTION: Chest wall instabilities after extensive injuries of its skeleton belong to the most serious chest trauma with a relatively high rate of complications and mortality, mainly due to its pathophysiological consequences for the respiratory system. OBJECTIVE: Retrospective analysis of an almost ten year file of injured patients treated with surgical stabilisation using instrumentation from Medin a. s. Company, Nové Mesto na Morave. PATIENTS AND METHODS: From the end of 1997 to the middle of 2006, 40 patients were treated with metallic fixation of the chest by the authors; including 35 men and 5 women with an average age of 50.4 years. Almost x of the cases represented block fractures of the ribs, flail chest type, separately or in combination with a fracture of the sternum. Traffic accidents predominated in the mechanisms of injury (75 %). More then three fourth of chest instabilities resulted from severe polytrauma. RESULTS: On average 4 plates were used for metallic fixation, 26 patients were indicated for the procedure directly due to chest wall instability; thoracotomy preceded in 9 patients with treatment of intrathoracic injury. Surgical stabilisation was performed in the mean on the 3.7 (th) day after injury. The period of subsequent artificial pulmonary ventilation usually did not exceed a week. One patient in the file died on sepsis due to bilateral bronchopneumonia (2.5 %), postoperative complications occurred in one fifth of patients, re-operation was performed in 16 patients. After a period of 11 months on average the implants were so far removed in 12 patients (30 %). CONCLUSION: Our experience with metallic fixation of the unstable chest wall is mainly positive. Decisive for the success of this procedure is the correct indication respectively selection of patients that will have a benefit from the surgical stabilisation.

Validity of simplified protocols to estimate glomerular filtration rate using iohexol clearance.

BACKGROUND: Iohexol clearance is an accurate and precise exogenous marker of glomerular filtration rate (GFR), but protocols are generally lengthy or require multiple sampling. Shorter or simpler protocols would be more practicable. METHODS: Two clearance estimates, two weeks apart, were undertaken in 11 healthy individuals and 26 diabetic patients with minimal to moderate renal impairment (chronic kidney disease stages 1-3). Blood specimens withdrawn at 60, 90, 120, 150, 180 and 240 min post-iohexol were analysed for iohexol. RESULTS: Visit 1 demonstrated excellent correlation with visit 2 (slope 1.00, confidence interval [CI] 0.88 to 1.13, intercept 0.94 mL/min/1.73 m(2), CI -9.9 to 11.8, P=0.43). The within-individual coefficient of variation (CV) of the 240 min reference method was 5.4% at a mean GFR of 84.1 mL/min/1.73 m(2). Single point estimates between 120 and 240 min had CVs of 4.5-7.0%, and did not differ from the reference method CV by more than 2.0 mL/min/1.73 m(2). Two and three point estimates in the interval 60-120 min post iohexol injection offered no advantages over these single-point estimates and overestimated at lower GFRs. CONCLUSIONS: An iohexol clearance estimate of GFR derived from a single sample taken between 2 to 4 h after infusion may provide a suitable tool for routine clinical use.

[Penetrating thoracic injury--seven-year experience with its diagnostics and treatment]. / Penetrující poranení hrudníku--sedmileté zkusenosti s diagnostikou a lécbou.

AIM OF THE STUDY: A retrospective analysis of seven-year follow-up results of subjects treated for penetrating thoracic injuries, aimed at optimalizing the diagnostic-therapeutic algorithm. MATERIAL AND METHODOLOGY: During 2000-2006, 39 subjects with penetrating thoracic injuries (35 males and 4 females, their mean age was 40.5 years), were diagnosed and treated in the authors' clinic. Cold weapon attacks were the commonest mechanism of the injuries (54%). The injury resulted in pneumothorax, resp. hemothorax, in, nearly, half of the subjects. The mean ISS value in the study group was 23. Less than a third of the injuried suffered associated injuries of the neck or abdominal regions. The diagnostics was based on clinical and x-ray examinations, resp. on thoracic CT. RESULTS: The commonest therapeutic procedure was draining of the pleural cavity (17 subjects). In 36% of the subjects, surgical revision via thoracotomy, resp. sternotomy, was inevitable. In two subjects, miniinvasive approach sufficed. Four subjects were treated conservatively. Two patients exited immediately following their transport to hospital, no therapeutic management was possible. No other deaths following the treatment were recorded, postoperative complications occurred in 4 subjects (10%), and they, equally, required 4 reoperations. CONCLUSION: The diagnostic process of penetrating thoracic traumas is based on clinical examination and x-ray, resp. thoracic CT. Most injuries are sufficiently managed using good quality drainage of the pleural cavity. Only few cases require urgent surgical revision via thoracotomy or sternotomy. Selected cases, mainly including stab injuries, may be successfully treated using miniinvasive techniques.

Higher serum C-reactive protein predicts short and long-term outcomes in peritoneal dialysis-associated peritonitis.

We examined the association between C-reactive protein (CRP) and short- and long-term adverse outcomes in peritoneal dialysis (PD)-associated peritonitis. Serum CRP levels were measured at baseline and 3 weeks after initiation of treatment in 209 patients with an incident episode of peritonitis between 1 January 1999 and 31 March 2005. Patients were followed until 31 May 2005. Short-term adverse outcomes included switch to hemodialysis, death, persistent infection beyond planned therapy duration, and relapse; long-term adverse outcomes included a subsequent peritonitis event or death. After adjustment for age, gender, diabetes, duration of renal replacement therapy and causative organism, patients with higher CRP levels at diagnosis had a greater odds of an adverse short-term outcome (odds ratio 1.57 (95% confidence interval (CI): 0.61-4.02), 2.73 (95% CI: 1.09-6.87), and 3.38 (95% CI: 1.36-8.42) in the second, third, and highest quartiles). In patients who met criteria for resolution of peritonitis 3 weeks after diagnosis, those with higher CRP levels had a greater risk of a long-term adverse outcome (hazard ratio 1.79 (95% CI: 1.05-3.07)). In conclusion, higher levels of CRP are independently associated with adverse outcomes in PD-associated peritonitis. Serial measurement of this marker during the course of peritonitis may facilitate earlier identification of individuals at greater risk of complications.

Cognitive function in Stage 5 chronic kidney disease patients on hemodialysis: no adverse effects of lanthanum carbonate compared with standard phosphate-binder therapy.

Patients with Stage 5 chronic kidney disease who have hyperphosphatemia require treatment with phosphate binders to lower serum phosphorus levels. Existing binders are effective but may be associated with important safety disadvantages. Lanthanum carbonate is a phosphate binder with demonstrated efficacy, safety, and tolerability in clinical trials. Changes in cognitive function were evaluated over time using the Cognitive Drug Research computerized cognitive assessment system (Simple Reaction Time, Digit Vigilance Task, Choice Reaction Time, Numeric Working Memory, and Delayed Picture Recognition) in 360 hemodialysis patients who were enrolled in a 2-year, multicenter, comparative study of lanthanum carbonate versus standard therapy. A decline in cognitive function from baseline was observed in both groups. The deterioration in cognitive function was similar in both the lanthanum carbonate and standard therapy groups. One parameter - Numeric Working Memory - showed a statistically significant between-group difference in favor of lanthanum carbonate (P=0.02). Given the magnitude of the changes, however, and the differences that were observed at baseline between treatment groups, the clinical significance of this difference is doubtful. This study demonstrates that cognitive function deteriorates in hemodialysis patients over a 2-year time period. Use of lanthanum carbonate as a phosphate binder does not adversely affect cognitive function compared with standard therapy.

Effects of carnitine supplementation on muscle metabolism by the use of magnetic resonance spectroscopy and near-infrared spectroscopy in end-stage renal disease.

BACKGROUND/AIM: A defect in skeletal muscle mitochondrial metabolism develops in patients with chronic renal failure on haemodialysis. Treatment with carnitine, a compound essential for normal mitochondrial function, has been suggested to have significant benefits in such patients, so we carried out a study to see if carnitine acts by improving muscle bioenergetics and function. METHODS: In a phase II randomised double-blind trial, patients with end-stage renal disease received placebo or intravenous L-carnitine (20 mg/kg dry body weight three times weekly after haemodialysis) for 16 weeks (n = 13 in each group). 31P magnetic resonance spectroscopy, 1H magnetic resonance imaging and near-infrared spectroscopy were used to measure muscle bioenergetics and function at baseline and at 16 weeks. RESULTS: There were no significant differences between groups at baseline. Mean plasma carnitine rose 10-fold in the carnitine group but was unchanged in the placebo group. L-carnitine had no statistically significant effect on any of the parameters measured. The rate of proton efflux from muscle, as a measure of tissue perfusion, was low in both groups and was not affected by treatment. CONCLUSIONS: The study failed to show any significant effect of 16 weeks' L-carnitine supplementation on these objective measures of muscle metabolism and function. Slow proton efflux from muscle provides evidence supporting low blood flow and, therefore, decreased oxygen availability, as an underlying mechanism for muscle mitochondrial dysfunction in this disorder.

Giant lichenification of the scalp.

Lichenification is characterized clinically by thickening of areas of skin as a result of the itch-scratch cycle and therefore is seen in conditions associated with chronic pruritus. The characteristic feature of giant lichenification is the occurrence of tumour-like growths with a warty cribriform surface. We describe a renal transplant patient presenting with giant lichenification of the scalp following an attack of herpes zoster at the same site. Chronic pruritus following scalp dysaethesia secondary to herpes zoster was considered the most likely explanation for the occurrence of these lesions.

Clinical usefulness of cystatin C for the estimation of glomerular filtration rate in type 1 diabetes: reproducibility and accuracy compared with standard measures and iohexol clearance.

OBJECTIVE-Assessment and follow-up of early renal dysfunction is important in diabetic nephropathy. Plasma creatinine is insensitive for a glomerular filtration rate (GFR) >50 ml/min and creatinine clearance is unwieldy and subject to collection inaccuracies. We aimed to assess the reproducibility, reliability, and accuracy of plasma cystatin C as a measure of GFR ranging from normal to moderate impairment due to type 1 diabetes in the presence of a normal plasma creatinine concentration. RESEARCH DESIGN AND METHODS-A sensitive immunoturbidimetric cystatin C assay was examined in 29 subjects with type 1 diabetes and 11 nondiabetic subjects. Duplicate measurements of the following were collected from each subject, 2 weeks apart: cystatin C, enzymatic plasma creatinine, 24-h creatinine clearance, GFR estimated from plasma creatinine by the Cockcroft-Gault equation, and iohexol clearance as a gold standard. RESULTS-Iohexol clearance ranged from 35 to 132 ml. min(-1). 1.73 m(-2). Plasma cystatin C compared well with the other clinically used tests. The reliability of cystatin C, as assessed by the discriminant ratio, was superior to creatinine clearance (3.4 vs. 1.5, P < 0.001) and the correlation of cystatin C with iohexol clearance (Rs -0.80) was similar to that of creatinine clearance (Rs -0.74) and superior to that of plasma creatinine and the Cockcroft-Gault estimate (Rs -0.54 and 0.66, respectively). Duplicate estimations were used to provide an unbiased equation to convert plasma cystatin C to GFR. CONCLUSIONS-Based on this study, cystatin C is a more reliable measure of GFR than creatinine clearance, is more highly correlated with iohexol clearance than plasma creatinine, and is worthy of further investigation as a clinical measure of GFR in type 1 diabetes.

[Microsurgical vasovasostomy in the age of modern reproduction medicine. A cost-benefit analysis]. / Die mikrochirurgische Vasovasostomie im Zeitalter der modernen Reproduktionsmedizin. Eine Kosten-Nutzen-Analyse.

WS represents the standard procedure of choice for the treatment of obstructive azoospermia following vasectomy. However, recently, ICSI has been suggested by some to represent the solution for all cases of male factor infertility regardless of its etiology based on its success rates. Therefore, we compared VVS to MESA/TESE and ICSI in terms of pregnancy, complications, and costs. Between 1/93 and 6/98 157 VVS was performed microsurgically using the 2-layer technique in 157 patients following prior vasectomy. Between 9/94 and 9/97 69 couples underwent MESA/ICSI for epididymal obstruction not amenable to micro-surgical reconstruction such as post-inflammatory obstruction and congenital absence of the vas deferens; in the same time period 42 couples underwent TESE/ICSI for azoospermia of testicular origin due to cryptorchidism, testicular atrophy, obstruction of the rete testis. In most cases MESA or TESE and ICSI were performed metachronously. Mean intervall of vasal obstruction was 7.6 (0.5-18) years; patency after VVS was 77%, pregnancy rate was 52%. Local complication rate was 4.7%, no major complications were observed. Costs per life birth after VVS were as high as 5,447,-DM or 2,800 Euro. Pregnancy rates after MESA/TESE and ICSI were 22.5% and 19.5%, respectively with 16 singletons, 3 twins and 3 abortions; local complications occurred in 3.9% of the men. Multiple birth were noticed in 15.8% following ICSI, but only in 0.7% following VVS. 5.7% and 1.4% of the female partners experienced serious complications as a mild or severe ovarian hyperstimulation-syndrome, respectively. Costs per life birth after MESA/TESE cycle were as high as 28,804,-DM or 14,100 Euro. Even in the era of ICSI microsurgical vasovasostomy represents the standard approach for obstructive azoospermia following vasectomy. Based on a cost-benefit analysis VVS is more successful in terms of pregnancy rates (52% vs. 22.5%). We conclude that MESA/ICSI should be reserved for patients not amenable for microsurgical reconstruction.

Microsurgical vasovasostomy versus microsurgical epididymal sperm aspiration/testicular extraction of sperm combined with intracytoplasmic sperm injection. A cost-benefit analysis.

PURPOSE: Vasovasostomy (VVS) represents the standard therapy of choice for the treatment of obstructive azoospermia following vasectomy. However, recently, intracytoplasmic sperm injection (ICSI) has been suggested by some to represent the solution for all cases of malefactor infertility regardless of its etiology based on its success rates. Therefore, we compared VVS to microsurgical epididymal sperm aspiration (MESA)/testicular extraction of sperm (TESE) and ICSI in terms of pregnancy, complications, and costs. PATIENTS AND METHODS: Between 1/93 and 6/98, 157 VVS were performed microsurgically using the double-layer technique. Between 9/94 and 9/97, 69 and 42 couples underwent MESA/ICSI and TESE/ICSI, respectively, for epididymal obstruction and azoospermia of testicular origin. RESULTS: The mean interval of vasal obstruction was 7.6 (0.5-18) years; patency after VVS was 77%, pregnancy rate was 52%. Local complication rate was 4.7%, no major complications were observed. Costs per life birth after VVS were 5,447 DM or 2,793 Euro. Pregnancy rates after MESA/TESE and ICSI were 22.5 and 19.5%, respectively, with 16 singletons, 3 twins and 3 abortions; local complications occurred in 3.9% of the men. Multiple births were noticed in 15.8% following ICSI, but in only 0.7% following VVS. 5.7 and 1.4% of the female partners experienced serious complications (mild or severe ovarian hyperstimulation syndrome, respectively). Costs per life birth after a MESA/TESE cycle amounted to 28,804 DM or 14,547 Euro. CONCLUSIONS: Even in the era of ICSI, microsurgical VVS represents the standard approach for obstructive azoospermia following vasectomy. Based on a cost-benefit analysis, VVS is more successful in terms of pregnancy rates (52 vs. 22.5%). VVS does not expose the female partners to complications following treatment of male infertility. In contrast to ICSI, multiple birth rates do not increase after VVS. We conclude that MESA/ICSI should be reversed for patients who are not amenable for microsurgical reconstruction.

Disturbance of cerebral function in people exposed to drinking water contaminated with aluminium sulphate: retrospective study of the Camelford water incident.

OBJECTIVE: To establish whether people exposed to drinking water contaminated with 20 tonnes of aluminium sulphate in the Camelford area of Cornwall in the south west of England in July 1988 had suffered organic brain damage as opposed to psychological trauma only. DESIGN: Retrospective study of affected people. PARTICIPANTS: 55 affected people and 15 siblings nearest in age to one of the group but who had not been exposed to the contaminated water were studied. MAIN OUTCOME MEASURES: Various clinical and psychological tests to determine medical condition and anxiety levels in affected people. Assessment of premorbid IQ (pFSIQ) with the national adult reading test, a computerised battery of psychomotor testing, and measurement of the difference in latencies between the flash and pattern visual evoked potentials in all participants. RESULTS: The mean (SE) pFSIQ was above average at 114.4 (1.1). The most sensitive of the psychomotor tests for organic brain disease was the symbol digit coding (SDC) test (normal score 100, abnormal <85). PARTICIPANTS performed less well on this test (54.5 (6.0)) than expected from their pFSIQ (P<0.0001) and a little less poorly on the averaged less discriminating tests within the battery (86.1 (2.5), P<0.0001). In a comparison with the 15 sibling pairs (affected people's age 41.0 (3.3) years v sibling age of 42.7 (3.1) years (P=0.36) the exposed people had similar pFSIQ (114.7 (2.1)) to their siblings (116.3 (2.1), (P=0.59) but performed badly on the symbol digit coding test (51.8 (16.6)) v (87.5 (4.9) for siblings, P=0.03). The flash-pattern differences in exposed people were greater than in 42 unrelated control subjects of similar age (27.33 (1.64) ms v 18. 57 (1.47) ms, P=0.0002). The 15 unexposed siblings had significantly better flash-pattern differences than their affected siblings (13.4 (2.4) ms v 29.6 (2.9) ms, P=0.0002). No effect of anxiety could be shown on these measurements from the analysis of the anxiety scores of exposed people. CONCLUSION: People who were exposed to the contaminated water at Camelford suffered considerable damage to cerebral function, which was not related to anxiety. Follow up studies would be required to determine the longer term prognosis for affected individuals.

Silicon and aluminium interactions in haemodialysis patients.

BACKGROUND: Aluminium toxicity in dialysis patients is well described. Aluminium has a close chemical affinity with silicon. Silicon may have a role in protection against aluminium toxicity. METHODS: We measured serum aluminium and silicon levels from haemodialysis patients from four different centres. RESULTS: Though no relationship was seen across all centres combined, in one centre there was a reciprocal relationship in patients on home haemodialysis (who did not require reverse osmosis). Median (range) aluminium levels were higher, 2.2 (0.4-9.6) micromol/l when serum silicon was less than 150 micromol/l, and lower, 1.1 (0.2-2.8) micromol/l when serum silicon levels were greater than 150 micromol/l (P = 0.03). CONCLUSIONS: In patients treated by haemodialysis without reverse osmosis high serum silicon concentrations were associated with lower serum aluminium concentrations than those with low serum silicon. Further work needs to confirm a preventative role for silicon in the accumulation and subsequent toxicity of aluminium in dialysis patients.