Platelet-neutrophil interactions during hemodialysis: a proposed biocompatibility approach

Platelet interaction with neutrophils may occur to a significant degree during hemodialysis (HD). We have recently shown that the enhanced neutrophil reactive oxygen species (ROS) production during the early phase of HD with cuprophan (CUP) is sustained by neutrophils which have bound platelets through P-selectin (CD62P). The evaluation of platelet-neutrophil interactions during dialysis offers the novel aspect of cell-cell interactions as a new parameter for studying the biocompatibility of dialyzer membranes. By the use of flow cytometry techniques, the present study was set up to analyze intradialytic platelet-neutrophil coaggregate formation and neutrophil ROS (hydrogen peroxide) production from 6 HD patients each dialysed with CUP, cellulose diacetate (CDA), polymethylmethacrylate (PMMA), and polyacrylonitrile (PAN) in a cross-over clinical trial. Platelet-neutrophil coaggregate formation (percentage of neutrophil cells positive for CD62P) and ROS production by neutrophils (total population; CD62P+ cells; CD62P- cells) were determined before HD and after 10', 20'and 40'. CD62P+ neutrophils significantly increased during HD with CUP (10', 20', 40'), PMMA (20') and CDA (20), while no change was observed with PAN. The difference between CUP and the other membranes was significant at 10', 20' and 40'; at 20', PMMA vs PAN p<0.005. ROS production by total neutrophil population significantly increased with CUP (10', 20), PMMA (20) and CDA (20'). The increase with CUP was higher at 10' when compared to CDA (p<0.020) or PAN (p<0.005), and at 20' versus the other three membranes; at 20' PMMA vs PAN p<0.005. Only neutrophils gated in neutrophil-platelet coaggregate areas (CD26P+ neutrophils) produced hydrogen peroxide. ROS production by CD62P+ neutrophils significantly increased with CUP (10', 20), PMMA (20') and CDA (20'). The increase with CUP was significantly (p<0.0002) higher than the other three membranes at 10' and 20'; at 20', PMMA vs PAN p<0.02. With each membrane, ROS production by CD62P- neutrophils showed no significant change at any time point during HD. The results of the present study indicate that interactions between platelets and neutrophils can mediate some pathophysiological abnormalities associated with hemodialysis treatment. Our data show that cellulose diacetate, a modified cellulosic membrane, exhibits a biocompatibility profile in terms of platelet-neutrophil interactions improved as compared to the parent cellulose membrane and comparable to that of some synthetic membranes. Our data also show that there is considerable variability in the biocompatibility of synthetic membranes. Though cellulosic membranes are generally considered as being less biocompatible than synthetic membranes, our results indicate that classification of membranes by biocompatibility is more complex than a simple division into cellulosic and synthetic membranes, especially with the advent of modified cellulosic membranes.

Efficacy and tolerability of recombinant human erythropoietin treatment in pre-dialysis patients: results of a multicenter study

Chronic renal failure is characterized by a normochromic normocytic anemia, the severity of which generally increases during progression toward uremia. The purpose of the study was to evaluate the efficacy and safety of recombinant human erythropoietin (rHu-EPO) given subcutaneously (s.c.), the dose required to reach and maintain Hb levels within 10 and 11 g% and its effects, if any, on the progression of chronic renal failure. Eighty-four pre-dialysis patients (46 F, 38M, age 61.7+/-13.9 years) with Hb levels between 6 and 9 g% and serum creatinine ranging from 3 to 9 mg/dl were treated with s.c. rHu-EPO (2000 U/twice weekly). After 6 weeks, if Hb increase was below 1 g%, 1000 U of s.c. rHu-EPO were added at each administration (3000 U twice weekly). Once the Hb target was reached (10-11 g%), the rHu-EPO weekly dose was halved and administration reduced to once weekly. The patients showed a significant rise in mean Hb values (p<0.001) after 3 months. Mean Hb values were as follows: 8.00+/-0.77 g% (pretreatment), 9.35+/-1.0 (3rd month), 10.06+/-1.04 (6th month), 10.25+/-0.62 g% (12th month). The mean rHu-EPO doses were 4000 U/w (start of the study), 3592+/-1685 U/w (6th month), 2840-/+1178 U/w (12th month). Renal function was evaluated by plotting the reciprocal of serum creatinine values vs time with a two period comparison: period A (retrospective-8 mo); period B (prospective-12 mo). The residual renal function was not impaired by rHu-EPO therapy. Meanwhile, no relevant modifications were observed in mean blood pressure values. Low doses of s.c. rHu-EPO were well tolerated, safe and effective; this therapeutic approach should therefore be considered for the improvement of anemia in pre-dialysis patients. A slow and gradual correction of anemia induces an improved sense of well being and a more active of life style.

N-3 polyunsaturated fatty acid supplementation in chronic progressive renal disease

Chronic renal failure (CRF) may be accelerated by secondary lipid and immune abnormalities which could be antagonized by polyunsaturated fatty acid (PUFA). We examined 20 CRF patients on conservative treatment, randomized in two groups: G1 consisted of 10 control patients and G2 10 patients supplemented for 12 months with a 3.4 g daily dose of PUFA. In basal conditions and after 12 months the following parameters were checked: creatinine clearance (CCr), daily urinary protein excretion per unit of residual renal function (UProt/CCr), rate of progression of renal insufficiency (delta CCr); triglycerides (TG), total (TC), HDL (HDALC) and LDL (LDLC) cholesterol, apolipoproteins Apo Al, Apo B, lipoprotein(a) Lp(a); lymphocyte subpopulations; spontaneous (c) and stimulated (s) cytokines IL-1 beta, IL-2, tumor necrosis factors TNF-alpha secretion by peripheral mononuclear cells. The groups did not differ in their basal parameters, which did not change in G1 during follow-up. In G2 the following parameters, initially higher than normal significantly decreased after 12 months: TG (2.9 +/- 0.45 to 2.6 +/- 0.3 mmol/l p < 0.005), Apo B (1.40 +/- 0.37 to 1.22 +/- 0.36 g/l, p < 0.05), c TNF-alpha (1008.1 +/- 534.9 to 726.8 +/- 458.7 pg/ml, p < 0.05). Spontaneous (c) IL-1 beta (216.7 +/- 116.2 to 150.5 +/- 107.8 pg/ml, p < 0.05), c IL-2 (124.5 +/- 43.8 to 101.6 +/- 25.8 pg/ml, p < 0.05), and s TNF-alpha (2456.4 +/- 908.3 to 1632.2 +/- 497.1 pg/ml, p < 0.005) also decreased, although already within the normal range at baseline. G2 patients experienced a steady monthly reduction of CCr whereas it rose progressively in G1 (p < 0.05), with a simultaneous increase in UProt/CCr (p < 0.05). PUFA are beneficial on the lipid and immune abnormalities secondary to CRF and may also have a useful effect on the progression of chronic renal damage.

Neutrophil reactive oxygen species production during hemodialysis: role of activated platelet adhesion to neutrophils through P-selectin

Platelet interaction with leukocytes can occur to a significant degree during hemodialysis, but it remains to be determined what pathophysiological consequences stem from the intradialytic formation of platelet-leukocyte coaggregates. By the use of flow cytometry techniques, this study was set out to analyze intradialytic platelet-neutrophil coaggregate formation and neutrophil hydrogen peroxide production from 10 end-stage renal disease patients each dialyzed with cuprophane and polyacrylonitrile membranes. Platelet-neutrophil coaggregates increased during dialysis with cuprophane, whereas no changes occurred with polyacrylonitrile membranes. Dialysis with cuprophane, unlike that with polyacrylonitrile, also resulted in a significant increase in neutrophil hydrogen peroxide production 10 min after dialysis initiation which persisted at significantly higher levels than predialysis values through the first 20 min. We found that the increased hydrogen peroxide production by neutrophils essentially occurred in concomitance with neutrophil-platelet coaggregation. Intracellular fluorescence representing hydrogen peroxide formation significantly increased through the first 20 min of cuprophane dialysis in neutrophils aggregated to platelets. By contrast, no change occurred in neutrophils not aggregated to platelets. Neutrophils which had formed aggregates with platelets produced higher hydrogen peroxide levels, as assessed by significantly higher fluorescence values, than non-aggregate-forming neutrophils at all time points tested. The phenomenon was duplicated in vitro when ADP-activated normal platelets were incubated with neutrophil cells but was largely inhibited when ADP-activated platelets were treated with anti-P-selectin antibody before incubation with neutrophils. These results strongly suggest that platelet-neutrophil aggregates occurring during hemodialysis, representing cell-cell interactions with pathophysiological effects, may serve as a new parameter to assess biocompatibility.

Thyroid function and plasma selenium in chronic uremic patients on hemodialysis treatment

It has been shown recently that Selenium (Se), an essential trace element for humans, is involved in the regulation of thyroid function, since the enzyme that catalyzes the liver conversion of the thyroid hormone T4 to the more active form T3 is a selenoenzyme. In chronic uremic patients, low blood Se levels as well as thyroid function abnormalities are often found. The present study was carried out to verify whether any correlation exists between Se levels and thyroid function, and to evaluate possible changes in hormonal pattern during Se supplementation in 10 chronic uremic patients on hemodialysis (HD) treatment. Se was supplemented orally as sodium selenite over six consecutive months. Basic plasma Se levels were significantly lower in patients than in normal controls. Right from the start of Se supplementation, plasma Se concentration promptly normalized and leveled off in the normal range throughout the study. Significant increase of FT3 and reduction of TSH levels were detected during Se supplementation. In Se-supplemented patients, a significant direct correlation was also found between reverse T3 (rT3) and TSH, and a significant inverse correlation was found between Se and TSH. Our results suggest that Se deficiency in chronic uremic patients represents a factor influencing the thyroid function and that the Se status should be determined in the evaluation of thyroid metabolism in these patients.

Cell-associated adhesion molecules as early markers of bioincompatibility

BACKGROUND

Transient nature of adhesive interactions occurring during cell margination is mainly dependent on expression of selectins which are shed by activated cells. This shedding in the circulation may play an important role as anti-inflammatory mediator. Haemodialysis is also associated with P-selectin (CD62P)/sialyl-Lewis(x) (CD15s) interactions which mediate platelet-leukocyte coaggregation. We further investigated the mechanisms underlying leukocyte margination during haemodialysis.

METHODS

CD15s, CD11b and CD61 expression on circulating leukocytes from patients dialysed on synthetic membranes (modified polyacrylonitrile (SPAN), polysulphone (PS), and polyacrylonitrile (AN69) was assessed by cytofluorometry in a prospective crossover trial. We measured plasma levels C3a/C3a desArg, soluble CD62P, and CD62E molecules obtained from patients and healthy individuals.

RESULTS

Expression of CD11b and CD15s was upregulated on neutrophils from patients dialysed with SPAN and PS membranes during the dialysis session. A significant negative correlation was found between the expression of CD11b or CD15s molecules and neutrophil counts as well as between CD15s expression and monocyte counts during haemodialysis. As assessed by CD61 expression on leukocytes, we observed that platelets bound significantly onto both neutrophils and monocytes during dialysis with both membranes. A significant positive correlation was found between the expression of CD11b molecules and the percentage of CD61+ monocytes counts during SPAN and PS dialysis. We found a significant increase of soluble CD62P in plasma samples obtained from haemodialysed patients before the dialysis session as compared to the levels detected in plasma from healthy individuals.

CONCLUSIONS

This study documents a major role of CD15s, CD11b, CD61, CD62P molecules in the transient leukocytes activation and margination during haemodialysis on synthetic membranes despite their low complement-activating properties.

A new polymethylmethacrylate membrane for hemodialysis

High molecular weight (MW) solutes are not removed during conventional hemodialysis (HD), and their accumulation is thought to play a role in some long-term HD complications (anemia, bone and joint pain, neuropathy, itching). The present trial was conducted to evaluate the removal capacity during in vivo HD of a new polymethylmethacrylate (PMMA) membrane (Filtryzer BK-F, 1.3 m2) compared to conventional PMMA (BK-P, 1.6 m2) and to cellulose acetate (CA, 1.3 m2). BK-F dialyzers, with a pore size of 100 A degrees and 62% porosity, are designed to remove high MW substances. Ten stable anuric RDT patients (53 +/- 13 years) were treated for one week with each membrane in a randomized sequence. Plasma concentrations of creatinine, BUN and beta 2-microglobulin (beta 2-M) were measured before (b) and after (a) HD to determine the reduction rate for these substances (%). Beta 2-M concentration after HD was corrected for changes in distribution volume. Samples of spent dialysate were collected after 3 minutes, 120 minutes and at the end of HD sessions, and appropriately treated and concentrated for HPLC analysis. The reduction rate for BUN and creatinine was similar for the 3 membranes. BK-F showed a higher beta 2-M reduction rate than BK-P (p < 0.005) or CA (p < 0.0001). HPLC analysis of dialysate showed prevalent peaks < 4 kilodaltons (kDa) throughout HD for BK-P and CA. Solutes > 10 kDa were infrequently detected. Peak profile during HD with BK-F was quite different, showing a predominant peak > 50 kDa which also included albumin. However, albumin loss significantly decreased after 120 minutes and at the end of dialysis compared with the 3-minute values, and was lower than that reported in CAPD patients. With BK-F a peak of MW > 500 kDa was also detected which previous studies indicated as a range characterized by the presence of erythropoiesis inhibitors. Use of the BK-F membrane in HD could afford satisfactory removal of high MW substances, thereby preventing or controlling some long-term HD complications such as anemia or beta 2-M amyloid formation.

Geographic factors and plasma selenium in uremia and dialysis

The importance of selenium (Se) as an essential trace element for man has been increasingly recognized. Blood Se levels in chronic uremic patients are frequently reported to be lower than in controls. Definitive determination of the Se status in uremic patients, however, is hampered by the wide range of blood Se content in humans from different parts of the world. The present study was designed to assess and compare the Se status in two European populations from Rostock (Germany) and Chieti (Italy). Plasma Se levels were evaluated in healthy controls, chronic renal failure nondialyzed patients (CRF) and hemodialysis patients (HD). All Se determinations were performed in a single laboratory. The Se concentration was significantly higher (p < 0.005) in Italian healthy controls than in German healthy controls. In contrast, Se levels were similar in both CRF and HD patients from both cities. In both countries, the Se concentration in CRF and HD patients was significantly lower (p < 0.001) than in their corresponding controls, but no difference between CRF and HD was found. CRF and HD patients from the two countries showed quite similar laboratory and anthropometric data. In CRF patients in Chieti, a significant (p < 0.05) negative correlation between plasma Se and serum creatinine was found. In both HD groups, the length of time on HD and type of membrane dialyzer used did not influence the Se status. A significant positive correlation (p < 0.01) between Se levels and the protein catabolic rate was found in both HD groups. Uremia seems to be a strong factor which overrules the difference in Se levels that is present in healthy adults from different European countries. Uremia in itself may influence and level the Se concentration in patients with geographic diversity.

A major role for CD62P/CD15s interaction in leukocyte margination during hemodialysis

We investigated expression of several antigens on neutrophils and monocytes, involved in cell adhesion, from patients hemodialyzed with cellulosic and polyacrylonitrile membranes. Among the antigens tested only the expression of CD15s and CD11b was significantly increased on neutrophils and monocytes in patients dialyzed with cellulosic membranes. No changes occurred with polyacrylonitrile membranes. Leukocyte counts from patients dialyzed with cuprophane membranes decreased at the same time as expression of cellular CD15s increased, resulting in a significant negative correlation at all time points tested. No correlation was found between the drop of monocytes and their expression of CD11b. When CD15s expression increased on neutrophils and monocytes, we observed a concomitant increase of CD62P, a specific selectin of activated platelets. When whole blood cells were incubated with complement activated serum both antigens increased but not when cells were incubated with hrC5a. We also observed that CD61, a platelet phenotypic antigen, was present on leukocytes incubated with complement activated serum. At the time when platelet-leukocyte coaggregates decreased, CD62P expression remained stable on leukocytes, suggesting that both neutrophils and monocytes are able to trap either CD62P shed by activated platelets or soluble CD62P present in normal human serum. The present study documents a major role of P-selectin (CD62P)/sialyl-Lewis x (CD15s) interaction in the transient leukocyte margination during hemodialysis.

Selenium in uremia

The importance of selenium as an essential trace element for man has been increasingly recognized during the last several years. Selenium deficiency has been associated with cases of congestive cardiomyopathy, skeletal myopathy, anemia, enhanced cancer risk, elevated incidence of cardiovascular disease, immune system alterations, hair and nail changes, and abnormalities in thyroid hormone metabolism. These symptoms are frequently present in chronic uremic patients. Nevertheless, the prevalence and significance of selenium deficiency in the uremic syndrome is still not clearly defined. This article reviews the selenium status in chronic uremic patients, the supposed pathogenetic mechanisms of selenium disturbance in uremia, and the possible role of selenium deficiency on some uremic abnormalities.

Hemodialysis with regenerated cellulosic membranes does not reduce plasma selenium levels in chronic uremic patients

Selenium (Se) is considered an essential and very important trace element for humans. Se blood levels are frequently low in end-stage renal disease (ESRD) patients, but very little has been established concerning the mechanisms that could modify Se status in uremia, including a supposed dialysis-mediated Se depletion. In order to verify whether hemodialysis (HD) can induce a loss of Se, thereby leading or contributing to a low plasma Se concentration, we investigated the effect of HD procedure with the most commonly used regenerated cellulosic membrane (Cuprophan) on plasma Se levels in 20 uremic patients on HD for 62.5 +/- 49.4 months. Plasma Se levels were also determined in 15 chronic renal failure (CRF) nondialyzed patients and in 28 age-matched healthy controls. Se concentration was determined by atomic absorption spectrophotometry. Plasma Se levels of both HD patients (61.3 +/- 8.5 micrograms/L) and CRF nondialyzed patients (56.4 +/- 10.1 micrograms/L) were significantly lower than in normal subjects (78.3 +/- 9.7 micrograms/L, p < 0.001). In CRF nondialyzed patients, a significant (p < 0.05) negative correlation was found between the plasma Se concentration versus serum creatinine values. Within the HD group, plasma Se levels significantly increased after the HD procedure (72.8 +/- 17.2 micrograms/L, p < 0.02) together with hematocrit and total plasma protein values (p < 0.05 and p < 0.001, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduced human lymphocyte blastogenesis and enhancement of adenosine triphosphate (ATP) by L-carnitine

Carnitine is associated with lipid synthesis and its deficiency may lead to cardiomegaly with parenchymal lipid in the heart, kidney and liver. In our study we found that pretreatment of peripheral blood mononuclear cells (PBMC) with serial dilutions of L-Carnitine (100 micrograms/ml-1 pg/ml) inhibits, in a dose-dependent manner, lymphocyte DNA synthesis stimulated with PHA (20 micrograms/ml). L-Carnitine did not have any effect on resting PBMC. The maximum inhibition was found at 10 micrograms/ml of L-Carnitine. Moreover, in a time-course study and using an enzymatic analysis (ATP monitoring reagent), L-Carnitine enhanced ATP production on PBMC treated and untreated with PHA, reaching a maximum effect at 30 min incubation. In another set of experiments PBMC were treated with L-Carnitine alone and in combination with PHA, and the percent of receptors CD3, CD4, and CD8 were calculated with flow cytometry. After the cell incubation with L-Carnitine, the percent of all receptors studied did not change compared to L-Carnitine-untreated cells (controls). These data suggest that L-Carnitine inhibits, in a dose-dependent manner, lymphocyte blastogenesis induced by PHA, probably through the enhancement of ATP synthesis, which is considered an inhibitor of phospholipase C activity and a suppressor in lymphocyte cultures.

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.

Effects of uremia and dialysis on brain electrophysiology after recombinant erythropoietin treatment

Quantitative electrophysiologic assessments are sensitive and useful indices of clinical state, and they are valuable in evaluating brain electrical activity before and after recombinant human erythropoietin (r-HuEPO) treatment. To study the hypothesis that, theoretically, anemia might be a cause of brain dysfunction in uremia, the authors assessed 18 patients (10 men and 8 women) on hemodialysis (RDT, age range, 35-58 years) before treatment (T1), and after 12 weeks (T2) and 24 weeks (T3) of r-HuEPO treatment, utilizing the following electrophysiologic tests: visual evoked potentials (VEP), brainstem auditory evoked responses (BAER), and somatosensory evoked potentials (SEP). The r-HuEPO was injected subcutaneously two times a week after RDT to produce hematocrit (Hct) levels of 30-35%. This drug induced a decrement of latency in P100 VEP (134.2 +/- 7.9 msec in T1 versus 116.5 +/- 6.9 msec in T2, p < 0.001, and versus 107.6 +/- 5.7 msec in T3, p < 0.005) and in the four main components of BAER. The most significant SEP changes were P27-N35 from peroneal nerve (p < 0.01), as an augmentation of SEP amplitude. Correction of anemia with r-HuEPO leads to a significant improvement in brain function in patients on RDT. The increased Hct level leads to enhanced brain oxygen delivery, directly improving brain metabolism. When the Hct rises, cerebral blood flow falls from high levels to normal, decreasing delivery of uremic "toxins" to the brain. The decrease in cerebral blood flow may decrease intracranial pressure and, in this way, may exert its beneficial effects by a rheologic pathway.

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.

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.

Clinical effects of recombinant human erythropoietin in hemodialysis patients. Results of the "Abruzzo" Multicenter Trial

Anemia in regular dialysis treatment (RDT) patients is primarily due to a deficiency in renal-derived recombinant human erythropoietin (EPO). The aim of this study was to evaluate the results of a multicenter trial in 81 end-stage renal disease (ESRD) patients on RDT. An "open" study was conducted over 2 years; starting dose of r-HuEPO was 50 IU/kg/three times weekly i.v. and eventually was increased in steps of 25 Ul/kg/dialysis until 300 Ul/kg/week. Mean weekly dose per patient was 15 Ul/kg, with mean Hb increase of 27.5%. Mean hematocrit (Hct) levels increased in these patients from 22.9 +/- 2.5 to 31.7 +/- 2.8 (p less than 0.001) after 2 years of therapy. Both spontaneous and evoked potentials improved. The response to r-HuEPO is dose dependent; hypertension and hyperkalemia are the most common side effects, but they are easily controlled. Central nervous system function before and after treatment is improved, and seems consistent with an enhancement of patients' quality of life.

Therapeutic effects of simvastatin on hyperlipidemia in CAPD patients

A causal link between hypercholesterolemia due to elevated plasma concentrations of LDL and VLDL remnants of CAPD patients has been established. The effects of 24 weeks of treatment with Simvastatin, a new HMG coenzyme A-reductase inhibitor (at 20 and 40 mg/day) on serum lipid, lipoprotein, and apolipoprotein A-I and B concentrations, as well as safety parameters and subjective side effects, were evaluated in eight patients (mean duration CAPD 24.80 +/- 7.50 months, age 54.50 +/- 13.70 years). Maximal effects on plasma lipoprotein and apolipoprotein concentrations were achieved after 4 weeks, and remained stable thereafter during the study. Mean fasting plasma cholesterol concentrations decreased from 280.5 +/- 60.2 mg% to 190.2 +/- 40.4 mg/dl (p less than 0.005) (-47%); mean plasma LDL-cholesterol concentrations also decreased from 257.6 +/- 13.4 mg% to 190.5 +/- 15.4 mg/dl (p less than 0.001) (-35%). Apolipoprotein A and B concentrations decreased significantly from 1.78 +/- 0.19 to 1.40 +/- 0.22 g/L (p less than .005) and 1.81 +/- 0.26 to 1.38 +/- 0.20 g/L (p less than .005). These data substantiate the view that Simvastatin is well tolerated and that no serious clinical or adverse laboratory effects have been observed. It appears to be a promising drug for the effective control of hyperlipemia in a large proportion of hypercholesterolemic patients, reducing their cardiovascular morbidity while on CAPD.

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.

Multicenter comparative study of aztreonam and gentamicin in the treatment of renal and urinary tract infections

A multicenter comparative study was carried out to evaluate the efficacy of aztreonam and gentamicin in 186 patients with symptomatic renal or urinary tract infections. Patients were divided randomly into two groups: 94 patients received aztreonam 1 g/day intramuscularly and 92 patients received gentamicin 80 mg i.m. twice daily. The clinical and microbiologic results found a single daily dose of aztreonam to be more effective than gentamicin b.i.d. Furthermore, no evidence of side effects was seen with aztreonam. Such results are generally thought to ensure better compliance in outpatients.

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)

Effects of chronic biofiltration with PAN membranes on acid-base status: polycentric study

Effects of chronic biofiltration (BF) with PAN membranes on acid-base status (ABS): polycentric study. From the 39 cases in a polycentric study we selected 13 patients with metabolic acidosis (pH 7.23 +/- 0.03), marked reduction of plasma bicarbonate (15.4 +/- 2.2 mEq/l) and hyperkalemia (6.2 +/- 0.6 mEq/l). BF was performed with a continuous post-dilutional supply of HCO3 (85 mmol/h), and attained rapid normalisation of blood bicarbonates and serum potassium during the treatment. After 6 months of BF treatment the pre-dialytic ABS showed remarkable improvement, and values were normal after one year. The remaining 26 patients in the polycentric study, treated by chronic BF without severe acidosis, showed good dialytic tolerance. In 15 of them the supply of bicarbonate was too high (because of moderate post-BF alkalosis) and we had to reduce the buffer inflow to about 50 mmol/h.

Polycentric 384-month study of biofiltration (BF) with AN69s

Polycentric 384-month study of biofiltration (BF) with AN69s. Since January 1984, 39 uremic dialyzed patients have been included in a randomized prospective study, to evaluate the clinical utility of BF. The trial lasted 9.85 months/pt (384.15 months of total observations) and patients admitted had some not well controlled clinical signs: major acidosis, intradialytic cardiovascular instability, intolerance to acetate dialysis, hypercatabolism, neuropathy, etc. We obtained some positive effects: the incidence of intradialytic hypotension decreased 26.6%; interdialytic body weight gain fell from 3.1 to 2.7 kg (p less than 0.05) and the dialytic time per week was reduced from 12.3 to 10.0 hours (p less than 0.01). At the same time dry body weight increased from 62.4 to 64.6 kg with worthwhile improvement of the acid-base status (ABS) in all patients. This controlled trial showed that BF is particularly useful for patients suffering from severe acidosis and/or cardiovascular instability.

Preliminary report on the efficiency of combined haemodialysis-haemoperfusion treatment in chronic uraemia

The use of activated charcoal haemoperfusion can play a complementary role in the substitutive treatment of chronic uraemia. This study reports the preliminary results of a regular combined haemodialysis-haemoperfusion treatment. The effectiveness of this treatment was observed on the subjective symptomatology (anorexia, nausea, asthenia) and on the polyneuropathy evaluated by electrophysiological assessments. The biocompatability of the system proved satisfactory.

Present status of hemoperfusion/hemodialysis in Italy

The use of charcoal hemoperfusion in the treatment of chronic renal failure has been proposed and applied by several authors. The availability of coating membranes of increased biocompatibility currently allows a safer and wider use of this purifying technique. It has been recently demonstrated that long-term treatment with combined hemodialysis/hemoperfusion yields an improvement of certain dialysis-resistant uremic signs in patients on regular dialysis treatment, while in selected patients it affords a marked reduction (up to one-third) in the overall time of treatment per week. The tolerance of long-term treatment is good. In line with these findings, a multicenter study has been carried out in Italy with two main aims: (1) to see whether long-term treatment with charcoal hemoperfusion is really safe and substantially free from side effects; (2) to verify in a larger and more varied population of patients whether such long-term treatment actually improves certain uremic signs persisting despite adequate dialysis treatment. A third phase of the multicentric study (reducing the weekly time of treatment) is currently being worked on. Five nephrology and dialysis departments took part in the study: in Bologna, Rome, Chieti, Ancona, and Lecce.

[Spectrophotometric evaluation of N-acetyl-beta-glucosaminidase in urine]

A spectrophotometric method for the assay of N-Acetyl-beta-Glucosaminidase activity in human undiluted urines is described. The application of this method is recommended for its sensitivity (2,6 X 10(-4)M) and its rapid performance, because it represents a good alternative to current methods and essentially to the fluorimetric technique with which it has a significant statistical correlation. Estimates of normal individuals aged between 1-70 years are reported.

Checkerboard reversal pattern and flash VEPs in dialysed and non-dialysed subjects

In forty-three patients suffering from chronic renal failure (CRF; 32 non-dialysed, 11 dialysed) the flash VEP and the pattern VEP to different spatial (7.5', 15', 30', 60' checks) and temporal (2, 10, 20, 40 Hz) frequencies were investigated. Abnormally delayed flash VEPs were obtained in 53.6% of the cases; transient pattern VEPs had a delayed major positive deflection in 46% of the tested eyes and altered steady-state response in 58% with a total of 65% abnormal responses. Chronically dialysed subjects showed higher levels of altered VEPs for both the techniques. The shorter latencies normally observed with coarser checks in healthy people were maintained in CRF patients, resulting in an abnormal prolongation of the shift between high and low spatial frequencies. Higher statistical correlations linked the pattern VEP with blood urea nitrogen (P less than 0.001) and other renal chemistry than the flash VEP. These and other features could be ascribed to a specific involvement of a maculo-calcarine channel devoted to 'detailed' vision and suggest the usefulness of this method to provide a tool for the early detection of an encephalopathic uraemia.

EMG changes in chronically dialyzed uraemic subjects undergoing d, 1-Carnitine treatment

The deficiency of muscle Carnitine secondary to chronic dialysis frequently induces lipid storage in striated muscles associated with progressive myocardial involvement. Serial EMG recordings disclose the presence of several motor unit potential families in tibialis anterior muscle related to damage of peripheral nervous fibres and muscular districts due to the storage of lipid vacuoles. The administration of d,1-Carnitine to twenty chronically dialyzed uraemic patients significantly improved distal latency of the M response of the external peroneal nerve at the EDB muscle and the MUP properties suggesting a Carnitine-dependent amelioration of fatty acid oxidative processes both in muscle and Schwann cells. The main side effects following d,1-Carnitine oral administration (3 g/daily) is a myasthenia-like symptom complex that is promptly reversed on drug interruption.

Neurophysiological abnormalities in uraemic encephalopathy

Sophisticated electrophysiological assessments have been employed to display cortical alterations in uraemia and to follow the influence of haemodialysis treatment (RDT). Flash-Visual Evoked Responses (VERs); Pattern Reversal Visual Evoked Potentials (VEPs); Brain-stem Auditory Evoked Responses (BAERs); Electroencephalogram (EEG) with Berg's analysis of frequencies were recorded in 15 uraemic patients, 10 of whom subsequently started RDT. VER latency was delayed compared with controls and unmodified after RDT. VEP latency was similarly delayed returning to normal range with RDT. BAER, preliminarily recorded only in 10 patients, showed increased latency of waves I, III, V. EEG showed 7 to 10 and 10 to 13 Hz to be reduced, and after eight months of haemodialysis the 13 to 20 Hz band increased.