Efficacy and tolerance of acetate free biofiltration: a central Italian multicenter trial.

One hundred and thirteen patients from 51 dialysis units have been treated for 12 months on AFB using a high flux AN69 dialyzer (Filtral 12 or 16-Hospal), a buffer free dialysate (Na+ 139, K+ 2, Ca++ 2 mmol/liter, glucose 1 g/liter) and a reinfusate solution containing 145 mmol/liter HCO3Na. All of them had previously been stabilized on acetate dialysis (30 patients) or bicarbonate dialysis (46 patients) or different dialysis procedures (37 patients). AFB sessions were performed for 3.71 +/- 0.28 hrs, three times a week, at an average blood flow of 308 +/- 8.5 ml/min so as to ensure a stable Kt/V value > 1 (1.16 +/- 0.08). Blood samples were drawn monthly pre- and post-dialysis, for blood electrolytes, calcium, phosphate, chloride, urea, creatinine and uric acid, proteins and lipid profiles, hemochrome. Body weights, blood pressures and adverse side effects were recorded at each session. Using a mean infusion volume of 7.96 +/- 0.61 liter/session, post-dialytic bicarbonate values consistently > 25 mmol/liter (26.33 +/- 2.71) were achieved. Intradialytic occurrence of symptoms was very low at an average rate < 1.5 episodes patient/month. After 12 months of Tx an adequate control of uremia, of electrolytes, of Ca-PO4 balance and of BP was obtained. AFB gets a very high intradialytic tolerance and an excellent depurative capacity which contributes to the well being of the patients.

Electrophysiological aspects of nervous conduction in uremia.

Some neurophysiological techniques have been employed in clinical nephrology to record abnormalities of nervous conduction in central and peripheral pathways. The electrical monitoring on the peripheral and central nervous systems has allowed the detection of uremic neural injury, the diagnosis of specific electrophysiological abnormalities, the evaluation of various treatments employed and the identification of those abnormalities that uremia can induce. A group of 156 subjects subdivided into four groups were examined: 100 healthy subjects (64 M, 36 F); 56 patients (21 glomerulonephritis, 14 pyelonephritis, 5 nephrolithiasis, 5 polycystic kidney, 4 nephroangiosclerosis, 7 undetermined) with chronic renal failure treated with a conventional low nitrogen diet (CLND, 0.6 g/kg b.w./d. of proteins), 8 of whom passed from CLND to a very low nitrogen diet supplemented with alpha-keto-analogues; a group of 22 of these 56 underwent a regular dialysis treatment for 12 to 15 hours/weekly for 40.5 +/- 10.2 months. Three patients of the CLND group and 13 patients underwent renal transplantation after a variable period of RDT. In the uremic patients we found different populations of motor unit potentials; a decreased MNCV was found in 35% of the CLND patients, RDT patients had slowed MNCV in 42%. The SNCV was compromised more frequently than the MNCV. An increased duration of evoked potentials was sometimes observed in CLND and RDT patients inducing us to consider this a hallmark of uremic syndrome. The alpha-keto-analogues and HD/HP treated patients showed an improvement in several features.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipids in the progression of chronic renal failure.

Lipid disturbances have been linked to the progression of chronic renal disease. We examined 52 patients with a creatinine clearance (CCr) of 38.5 +/- 7.9 ml/min due to various nephropathies, on free diet. Bimonthly, over a 12-month period, we assessed: serum creatinine (Cr); CCr; daily urinary urea excretion; urinary protein excretion per unit of residual renal function (UProt/CCr); total, HDL, VLDL and LDL cholesterol; triglycerides; Apo A, Apo B. Chronic renal failure was progressive in 22 patients with a slope of 1/Cr-0.00358 +/- 0.00247, stable in 30 with a slope of 0.00420 +/- 0.00285. Lipid parameters did not differ significantly between the two groups but for the lower Apo A and Apo A/Apo B ratio values in the progressive group. Overall slope inversely correlated with basal CCr; in the progressive patients the slope correlated with the percentage variation of UProt/CCr and only partially with the altered Apo profile.

The brainstem auditory evoked responses in Alport's syndrome.

Alport's syndrome is a "hereditary nephritis" associated with structural defects of basement membranes in kidneys, ears and eyes, with variable clinical expression. As the acoustic abnormalities are often subclinical, we studied the brainstem auditory evoked responses (ABR) and tonal audiometry in 12 patients (7 males, 5 females, mean age 32.50 +/- 16.70 years) with histologically documented renal lesions consistent with Alport's syndrome. ABR were used to document the altered acoustic-nerve conduction and transmission typical of the early stage of Alport's syndrome. In 11 patients (seven males, four females), we found bilateral delayed latency (I dx: 2.50 +/- 0.80 msec; III dx: 4.24 +/- 0.68 msec; V dx: 7.02 +/- 0.94 msec) and altered waveform I, III, V by ABR. By audiometry eight patients (six males, two females) showed a loss of medium-high tones, and this group included the patients with a negative ABR study. Therefore, the ABR is abnormal in Alport's syndrome; it may be positive in patients with normal tonal audiometry, usually all cochlear functions are grossly intact; the acoustic-nerve lesions in Alport's syndrome may precede the cochlear involvement and clinical hearing loss; the electrophysiological analysis does not identify the particular nervous structures involved in the acoustic pathways.

Zinc-mediated lymphocyte energy charge modification in dialysis patients.

The authors studied the effects of 6 months of zinc therapy on cell-mediated immunity in regular dialysis therapy patients. Serum zinc was significantly enhanced (p less than 0.01) at 2 months. While cells, OKT3, and OKT4 did not show significant variation, but after 6 months of therapy a significant (p less than 0.02) decrease of OKT8 cells, with enhancement of the OKT4/OKT8 ratio, and a significant (p less than 0.01) increase in the Multitest Composite score were found. At the same time, a significant elevation (p less than 0.001) of adenosine triphosphate (ATP), and a reduction (p less than 0.01) of lymphocyte adenosine monophosphate was seen; consequently, energy charge levels increased. Zinc-induced improvement of uremic lymphocyte function is likely mediated by an increase in intracellular ATP.

Computerised non-invasive monitoring of cardiovascular stress in haemodialysis patients.

Haemodynamic instability is one of the most frequent problems occurring during dialysis treatment. Ten clinically stable patients (8 M and 2 F) undergoing chronic maintenance haemodialysis for at least 6 months were investigated. Two groups of five patients each, were selected on the basis of presence (IG) or absence (SG) of cardiovascular instability during dialysis. The cardiovascular function was assessed by computerised electrical bioimpedance performed during dialysis setting and by echocardiography immediately pre- and post-dialysis. In SG dialysis treatment did not change cardiac index (CI), stroke index (SI) and systemic vascular resistances index (SVRI). However CI, SI and SVRI, tended to decrease in IG patients; the reduction in CI was primarily due to a decrease in SI. Ejection velocity index increased significantly in SG but not in IG. Evaluation of cardiac function by Döppler echocardiography revealed a significant increment in fractional shortening, mean velocity of circumferential fiber shortening and Suga' index in SG with dialysis but not in IG. Stress index decreased significantly in both groups. Hormonal and biochemical parameters were not significantly different before and after dialysis in both groups. In IG the decrease in mean blood pressure, due to a reduction of SI, recognises in the inadequate response of myocardial contractility to volume subtraction, the genesis of its drop. Finally, impedance cardiography in uraemic patients helps to identify the factors that contribute to the impairment of cardiac performance and that should be studied before selecting new and advanced dialysis programmes.

Nucleotide deficit and functional platelet alterations in patients on regular dialysis treatment (RDT).

In RDT patients hemocoagulative changes are repeatedly found; of these the most important are platelets' functional defects. Biochemical and biophysical modifications responsible for this pathology have not been completely clarified. In 20 non-thrombocytopenic patients, dialyzed 3 times weekly for over 1 year, we evaluated, using standard methodology, platelet adhesivity and aggregation induced by collagen and ADP at varying dosages. All blood samples were collected after the longest interdialytic period and just before dialysis. At the same time we evaluated the basic metabolic pool and, after collagen stimulation, the intraplatelet functional storage pool of ATP and ADP. The dosages were obtained using simple, reproducible and modern bioluminescence technique, which utilises microorganism light emission (bioluminescence) due to the oxidation of the bacterial substrate by catalyzing enzyme (luciferase) (1251 Luminometer LKB). We compared this data with that obtained from 40 healthy subjects. In the patients examined, adhesivity and aggregation result altered. The intraplatelet content of all nucleotides in both pools is significantly reduced if compared to the control group. The ATP and ADP concentration of both metabolic and functional pools cannot be correlated to the following: serum creatinine, BUN, calcemia, PTH, Hb. On the contrary we found that basal metabolic ATP values are inversely related (p less than 0.01) to serum phosphate levels. An analysis of results of this preliminary study leads us to hypothesize that hyperphosphatemia could interfere with intraplatelet glycolysis inducing a reduction of intracellular ATP. As all platelet functions are ATP and ADP dependent, we could consider the nucleotide deficit a cause of "uraemic platelet" disfunction, not modifiable with RDT but perhaps only through an appropriate control of phosphate levels.