Biocompatibility and Functional Performance of a Polyethylene Glycol Acid-Grafted Cellulosic Membrane for Hemodialysis

In order to improve the biochemical reactivity of the cellulose polymer, which is mainly attributed to the presence of surface hydroxyl groups, derivatized cellulosic membranes have been engineered replacing or masking some or all of the hydroxyl groups in the manufacturing process of the membrane. The present study was set up to analyze both biocompatibility and functional performance of two different derivatized cellulosic membranes (cellulose diacetate; polyethylene glycol, PEG, acid-grafted cellulose) as compared to a synthetic membrane (polymethylmethacrylate, PMMA). Cellulose diacetate is prepared by substituting hydroxyl groups with acetyl groups; PEG cellulose is obtained by grafting PEG chains onto the cellulosic polymer with a smaller amount of substitution than cellulose diacetate.

While the three dialyzers provided similar urea and creatinine removal, the dialyzer containing cellulose diacetate showed a reduced ability to remove β2-microglobulin compared to that containing PEG cellulose or PMMA. A transient reduction in leukocyte count was observed for both derivatized cellulosic membranes. The neutrophil and monocyte counts throughout the entire dialysis session showed a closer parallelism with the cellular expression of the adhesive receptor CD15s (sialyl-Lewis x molecole) than with CD11b/CD18 expression. Platelet activation, as indicated by the percentage of cells expressing the activation markers CD62P (P-selectin) and CD63 (gp53), occurred with all membranes at 15 min of dialysis and also with PMMA at 30 min. An increased formation of platelet-neutrophil and platelet-monocyte coaggregates was found at 15 and 30 min during dialysis with cellulose diacetate and PMMA but not with PEG cellulose. Generally in concomitance with the increase in platelet-neutrophil coaggregates, an increased hydrogen peroxide production by neutrophils occurred.

Our results indicate that derivatizing cellulose may represent a useful approach to improve the biocompatibility of the cellulose polymer, though some homeostatic reactions remain activated. Our results also indicate that there may be a great variability in the biocompatibility profile of derivatized cellulosic membranes which most likely stem from the different type of structural modification rather than from the degree of hydroxyl group replacement.

Leukocyte Adhesion Molecules and Leukocyte-Platelet Interactions during Hemodialysis: Effects of Different Synthetic Membranes

Membranes made from synthetic polymers, in general, are considered as being biocompatible membranes and tend to be treated as a homogeneous group. However, all of these membranes have multiple and different characteristics that may contribute to interactions with blood components. As a consequence, the biocompatibility profile of synthetic membranes may vary. In the present cross-over study, we examined by flow cytometry the effects (expressed as % change from predialysis values) of three different synthetic polymers (polysulfone, PSF; polyacrylonitrile-co-sodium methallyl sulfonate, AN69; ethylenevinylalcohol, EVAL) on the expression of leukocyte adhesion molecules (CD11b/CD18, CD15s) and the interactions between leukocytes and platelets under conditions of routine clinical use.

For neutrophils, a statistically significant difference was found in CD15s expression for EVAL as compared to AN69 (p<0.05) and in CD11b/CD18 expression for PSF as compared to both EVAL (p<0.01) and AN69 (p<0.05). No difference between membranes was found on the expression of such adhesive molecules on monocytes. Significant differences in platelet-neutrophil (but not in platelet-monocyte) coaggregate formation were observed between PSF and both EVAL (p<0.001) and AN69 (p<0.01). Reactive oxygen species production by neutrophil population during hemodialysis was significantly different between each pair of synthetic polymers (PSF vs EVAL, p<0.001; PSF vs AN69, p<0.001; AN69 vs EVAL, p<0.05).

Our data demonstrate that in terms of leukocyte adhesion receptors and platelet-leukocyte interactions, the biocompatibility profile of the synthetic membranes polysulphone, AN69 and EVAL shows many similarities but also several significant differences. Our results support the concept that biocompatibility evaluation of each membrane should be based exclusively on data generated by that membrane in order to avoid errors based on assumptions about group characteristics.

Endoscopy as a Tool for Diagnosing and Treating Gastrointestinal Angiodysplasia in Haemodialysis Patients

Gastroenteric angiodysplasia is an important cause of haemorrhage in chronic renal failure patients. This paper reports on 2 patients on maintenance haemodialysis with upper gastrointestinal bleeding due to different manifestations of angiodysplasic lesions (sudden appearance of haematemesis and melaena in one case, progressive anaemia with apparent resistance to erythropoietin in the other case). Exploratory endoscope examination of the first digestive tract showed in both cases the presence of bleeding angiodysplasic lesions. Both patients were there and then submitted to surgical endoscopy, during which the bleeding angiodysplasic lesion was sclerosed with physiological salt solution plus adrenaline 1/10000 and 1% polydocanol. In one patient, bleeding occurred again ten days later, making renewed surgical endoscopy necessary. In the course of this an elastic ligature was made to the superangular angiodysplasia. A year later in both cases there were no direct or indirect signs of further bleeding; an endoscopic check-up showed the treated lesions to be sclerosed. Endoscopy offers the unique possibility of being used for both diagnostic and therapeutic purposes in a single session. In expert hands, endoscope therapy is effective and markedly reduces the risk of side effects.

The natural history of uremic neuropathy

The results obtained by electrophysiological recording allow to discover the constant presence of alterations to the central and/or peripheral nervous system in the uremic syndrome. Thus, it becomes possible to demonstrate the existence of an actual 'uremic neuropathy'. Moreover, the results show the persistence and progression of uremic involvement in the course of dialytic treatment; only after kidney transplantation a return to normal takes place. Methodological and interpretative progress will allow us in the future to broaden our knowledge of uremia by providing a useful guide to therapeutic strategies.

Multicentric experience with combined hemodialysis/hemoperfusion in chronic uremia

A multicentric study was carried out to investigate the safety and effectiveness of long-term treatment of chronic uremic patients by a regular combination of hemodialysis and charcoal hemoperfusion. 39 RDT patients from five dialysis centers were treated for up to 12 months. The combined treatment proved to be safe, well tolerated and effective in improving certain dialysis-resistant uremic signs, mainly severe peripheral neuropathy, asthenia, anorexia, nausea, lack of well-being and relapsing pericarditis. There was also a marked decrease, after several weeks of combined treatment, in plasma values of urea, uric acid and creatinine.

[Use of oral hypoglycemic agents in patients with chronic kidney failure]

Type 2 diabetes mellitus is one of the most common disease worldwide. Diabetes mellitus is expected to affect over 380 million people by 2025 and one third of these patients will develop chronic kidney disease (CKD). There are many categories of hypoglycemic agents available for treatment of type 2 diabetes mellitus: sulphounilureas, glinides, biguanides, thiazolidinediones, alpha-glucosidase inhibitors, and the new brand incretines. In nephropatic patients with CKD stage I-II, any hypoglycemic agent can be used: the choice must be linked to a careful evaluation of potential risk and benefit. In CKD stage III to V, conversely, some drugs are not recommended while other agents can be used with dose reduction due to risk of hypoglycemia. In these patients the early use of insulin may be indicated. The target of this review is to evaluate evidences about the possible use of hypoglycemic agents in patients affected by diabetes and CKD stage III-V.

Wireless capsule endoscopy in the diagnostic of small intestine angiodysplasia in chronic uremic patient

Gastroenteric bleeding due to angiodysplasia (AD) is a relatively common occurrence in patients with end-stage renal failure. Gastric and colon angiodysplasic lesions can be easily revealed by endoscopic procedures, whereas lesions of the small intestine are more difficult to detect. Imaging modalities used in the diagnostic imaging algorithm for the detection of small-bowel AD, include non-invasive methods like enema-helical computer tomography,(99m)Tc-labelled red blood cell scintigraphy, and angiography, and invasive methods such as intraoperative enteroscopy. We report the cases of 3 hemodialysis patients with recurrent episodes of gastrointestinal bleeding, caused by small-bowel AD diagnosed by means of wireless-capsule endoscopy. In all cases, previous gastroscopy and colonoscopy were unrevealing. Wireless-capsule endoscopy consists in swallowing a capsule endoscope (11 mmx27 mm) which contains a miniature video camera, a light source, batteries, and a radio transmitter. Video images are transmitted by means of radio telemetry to aerials taped to the body that allow images to be captured. Moving images from a period as long as 6 h are stored on a portable recorder. Wireless-capsule endoscopy may prove valuable in the assessment of gastrointestinal bleeding in uremic patients with unrevealing results at gastroscopy and colonoscopy.

[Angiodysplasia of the small bowel: a possible cause of anemia even in mild chronic renal failure]

BACKGROUND

Gastroenteric angiodysplasia (AD) is a vascular lesion characterized by vascular ectasias to the submucous sheath of the gastrointestinal tract. Lesions can be flat or raised, isolated or grouped and can break or ulcerate causing acute hemorrhage or, more commonly, chronic bleeding.

CASE-REPORT

We describe a 65-year-old patient with a 3-yr history of chronic renal failure (CRF), who gradually developed anemia (hemoglobin (Hb) 10 g/dl) without any episodes of clinically relevant bleeding or any exposure to bleeding risk factors. Blood pressure (BP) was normal and renal function was stable (serum creatinine (Cr) 1.9 mg/dl). Routine laboratory tests showed a slight reduction in serum iron and transferrin saturation and a slightly elevated absolute reticulocyte count. These findings were associated with a positive occult gastrointestinal blood test and raised the clinical suspicion of chronic gastrointestinal blood loss. Oesophagogastro-duodenoscopy and colonoscopy demonstrated an absence of significant lesions, suggesting the need to investigate for a lesion localized in the small intestine. Capsular endoscopy, a recently developed endoscopic technique, particularly suited for small bowel pathology, was performed, and demonstrated the presence of an angiodysplasic lesion, located in the jejunum.

CONCLUSIONS

Our case report supports the necessity for a complete clinical and laboratory evaluation of the possible causes of anemia superimposed on relative erythropoietin deficiency in CRF patients. When gastrointestinal blood loss is suspected, the entire gastroenteric tract should be examined to search for the bleeding sites. Our report also demonstrates that AD could be responsible for gastrointestinal bleeding even in mild CRF and not only, as usually reported, in end-stage renal disease (ESRD). Capsular endoscopy offers the unique possibility to determine the bleeding site in the small intestine and appears as an effective diagnostic procedure in CRF patients.

[On-line HFR and removal of uremic toxins inducing the loss of phospholipidic asymmetry of the erythrocyte membrane]

The phospholipids of the erythrocyte membrane are normally distributed asymmetrically in the double layer with the aminophospholipid phosphatidylserine (PS) present only on the inside of the membrane, since its exposure on the outside has numerous physiopathological consequences. In previous studies we have observed that solutes retained in uremia cause increased exposure of PS on the outer surfaces of the erythrocyte membrane and that this phenomenon may be involved in the uremic physiopathology, reducing erythrocyte survival and encouraging abnormal erythrocyte-endothelium interactions. The capability of the extracorporeal blood clearance treatment in removing the circulating uremic factors, responsible for the increased exposure of PS in red blood cells (RBC), was evaluated in 6 chronic uremic patients treated with haemodialysis (HD) or with on-line HFR in a random cross-over perspective study. The PS removal was evaluated indirectly by measuring the expression of PS in normal RBC incubated with uremic plasma obtained at various moments of the clearance session. The capability of the uremic plasma to expose PS on the RBC of healthy subjects (n-times increase compared to incubation of normal RBC with autologous plasma) was essentially unmodified during HD (3.3 +/- 0.2 pre HD; 3.3 +/- 0.1 after 2 hours; 3.1 +/- 0.2 at the end of the session) but was reduced during HFR (3.1 +/- 0.2 pre HD; 2.3 +/- 0.1 after 2 hours; 1.6 +/- 0.1 at the end of dialysis; p<0.001 at the end of dialysis vs pre and after 2 hours and p<0.001 vs HD at 2 hours and at the end of the session). The reduced capability of the uremic plasma obtained during the HFR session to expose PS in normal RBC, proves removal of the plasmatic uremic factors able to externalize the PS. To assess whether this removal effect is linked to the cartridge containing styrene resin used in the treatment with HFR, samples of ultrafiltrate were taken before and after the cartridge and its capability to express PS on normal RBC was measured. The absolute RBC values expressing PS (%) were (pre-cartridge vs post-cartridge) 8.6 +/- 0.3 vs 3.8 +/- 0.2 after 5 minutes from the start of the session; 3.9 +0.1 vs 1.6 +0.2 halfway through the session; 3.1 +/- 0.1 vs 1.3 +/- 0.66 at the end of the session (p<0.005 pre vs post at all times). Our results show that uremic compounds able to cause increased exposure of PS in RBC can be removed during on-line HFR, mainly thanks to the adsorption properties of the cartridge containing resin. This removal might be of benefit to uremic patients, improving the anaemic condition and reducing abnormal RBC-endothelium interactions which may contribute to endothelial disorder during uremia.

Making the most of on-line recruiting

Ninety percent of large U.S. companies are already recruiting via the Internet. By simply logging on to the Web, company recruiters can locate vast numbers of qualified candidates for jobs at every level, screen them in minutes, and contact the most promising ones immediately. The payoffs can be enormous: it costs substantially less to hire someone on-line, and the time saved is equally great. In this article, Peter Cappelli examines some of the emerging service providers and technologies--matchmakers, job boards, hiring management systems software, and applicant-screening mechanisms that test skills and record interests. He also looks at some of the strategies companies are adopting as they enter on-line labor markets. Recruiting needs to be refashioned to resemble marketing, he stresses. Accordingly, smart companies are designing Web pages, and even product ads, with potential recruits in mind. They're giving line managers authority to hire so that candidates in cyberspace aren't lost. They're building internal on-line job networks to retain talent. Integrating recruiting efforts with overall marketing campaigns, especially through coordination and identification with the company's brand, is the most important thing companies can do to ensure success in on-line hiring. Along the way, Cappelli sounds two cautionary notes. First, a human touch, not electronic contact, is vital in the last steps of a successful hiring process. Second, companies must make sure that on-line testing and hiring criteria do not discriminate against women, disabled people, workers over 40, or members of minority groups. When competition for talent is fierce, companies that master the art and science of on-line recruiting will be the ones that attract and keep the best people.

Biocompatibility and functional performance of a polyethylene glycol acid-grafted cellulosic membrane for hemodialysis

In order to improve the biochemical reactivity of the cellulose polymer, which is mainly attributed to the presence of surface hydroxyl groups, derivatized cellulosic membranes have been engineered replacing or masking some or all of the hydroxyl groups in the manufacturing process of the membrane. The present study was set up to analyze both biocompatibility and functional performance of two different derivatized cellulosic membranes (cellulose diacetate; polyethylene glycol, PEG, acid-grafted cellulose) as compared to a synthetic membrane (polymethylmethacrylate, PMMA). Cellulose diacetate is prepared by substituting hydroxyl groups with acetyl groups; PEG cellulose is obtained by grafting PEG chains onto the cellulosic polymer with a smaller amount of substitution than cellulose diacetate. While the three dialyzers provided similar urea and creatinine removal, the dialyzer containing cellulose diacetate showed a reduced ability to remove 32-microglobulin compared to that containing PEG cellulose or PMMA. A transient reduction in leukocyte count was observed for both derivatized cellulosic membranes. The neutrophil and monocyte counts throughout the entire dialysis session showed a closer parallelism with the cellular expression of the adhesive receptor CD 15s (sialyl-Lewis x molecule) than with CD11b/CD18 expression. Platelet activation, as indicated by the percentage of cells expressing the activation markers CD62P (P-selectin) and CD63 (gp53), occurred with all membranes at 15 min of dialysis and also with PMMA at 30 min. An increased formation of platelet-neutrophil and platelet-monocyte coaggregates was found at 15 and 30 min during dialysis with cellulose diacetate and PMMA but not with PEG cellulose. Generally in concomitance with the increase in platelet-neutrophil coaggregates, an increased hydrogen peroxide production by neutrophils occurred. Our results indicate that derivatizing cellulose may represent a useful approach to improve the biocompatibility of the cellulose polymer, though some homeostatic reactions remain activated. Our results also indicate that there may be a great variability in the biocompatibility profile of derivatize cellulosic membranes which most likely stem from the different type of structural modification rather than from the degree of hydroxyl group replacement.

Endoscopy as a tool for diagnosing and treating gastrointestinal angiodysplasia in haemodialysis patients

Gastroenteric angiodysplasia is an important cause of haemorrhage in chronic renal failure patients. This paper reports on 2 patients on maintenance haemodialysis with upper gastrointestinal bleeding due to different manifestations of angiodysplasic lesions (sudden appearance of haematemesis and melaena in one case, progressive anaemia with apparent resistance to erythropoietin in the other case). Exploratory endoscope examination of the first digestive tract showed in both cases the presence of bleeding angiodysplasic lesions. Both patients were there and then submitted to surgical endoscopy, during which the bleeding angiodysplasic lesion was sclerosed with physiological salt solution plus adrenaline 1/10000 and 1% polydocanol. In one patient, bleeding occurred again ten days later, making renewed surgical endoscopy necessary. In the course of this an elastic ligature was made to the superangular angiodysplasia. A year later in both cases there were no direct or indirect signs of further bleeding; an endoscopic check-up showed the treated lesions to be sclerosed. Endoscopy offers the unique possibility of being used for both diagnostic and therapeutic purposes in a single session. In expert hands, endoscope therapy is effective and markedly reduces the risk of side effects.

Role of dyslipidemia in the progression of chronic renal disease

The connection between lipids and the rate of progression of chronic renal disease was retrospectively examined in 70 patients who were divided into 2 groups according to their baseline creatinine clearance (CCr): Group 1 (Gp1) contained 30 patients with CCr 60-40 mL/min followed for 40.0 +/- 13.3 months; Group 2 (G2) contained 40 patients with CCr 39-15 mL/min followed for 39.0 +/- 18.2 months. The following parameters were considered: basal and final CCr proteinuria per unit of CCr (UProt/CCr); the difference between final and basal UProt/CCr (delta UProt/CCr); the change in CCr/month (delta CCr); baseline triglycerides (TG), total (TC), HDL (HDLC) and LDL (LDLC) cholesterol, Apo AI, Apo B, Lp(a). Besides in basal CCr the 2 groups significantly differed in the final CCr, final UProt/CCr, delta UProt/CCr, delta CCr. No differences were observed concerning lipid parameters except for Lp(a) (G1 14.8 +/- 13.6, G2 28.7 +/- 27.4 mg/dL; p < 0.05). Baseline TG (G1 184.1 +/- 61.3, G2 187.5 +/- 72.1 mg/dL) and Apo B (only G2 1.05 +/- 0.32 g/L) were significantly higher than normal subjects and the Apo AI/Apo B ratio (G1 1.42 +/- 0.43, G2 1.33 +/- 0.45) were significantly lower than in normal subjects. delta CCr, while inversely correlated in both groups with delta UProt/CCr (p < 0.01), only in G2 did it correlate directly with the Apo AI/Apo B ratio (p < 0.05) and inversely with Apo B and LDLC (p < 0.05). Although a correlation between Lp(a) and delta CCr was not found, 20/22 patients (3/5 G1, 17/17 G2) with a level > 30 mg% ran a progressive course. A natural progression of CRI, heralded by an increasing UProt, is highly frequent when baseline CCr is < 40 mL/min; only then lipids seem to add a burden to the renal damage.

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.

Low-dosage ibopamine treatment in progressive renal failure: a long-term multicentre trial

A multicentre trial (11 nephrology centres) was carried out to test the effects of ibopamine, an orally active dopamine-like drug, on the progression of chronic renal failure. For a 2-year period 189 chronic renal failure patients (serum creatinine level 1.5-4.0 mg/dl) were observed. They were homogeneous for basic nephropathy, degree of residual renal function, blood pressure, and proteinuria. The patients were randomly divided into two groups: 96 took ibopamine at a dosage of 100 mg/day (group A) and 93 served as controls (group B). All were on a low-protein diet (mean 0.8 g/kg body weight). By the end of the observation period, the rate of decrease of the renal function indexes in time proved significantly slower (1.8 times) in group A than in group B. The survival curves for renal function (pre-established end points were creatinine level increases equal to or > 20% and equal to or > 40% of the basal values) proved significantly better (p < 0.02 and p < 0.002 respectively) in group A than in group B. The mean plasma creatinine values rose by 17% in group A and by 36% in group B. The creatinine clearance decreased by 5% in treated patients and by 14% in the controls. Statistical analysis ruled out any possible centre effect. The trial suggests that low-dosage ibopamine administration may be used as a valid and safe pharmacological adjunct for retarding the progression of renal failure in patients with mild or moderate chronic renal impairment.

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.

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.

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)

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.

[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.