Redox state, antioxidative activity and lipid peroxidation in erythrocytes and plasma of chronic ambulatory peritoneal dialysis patients

Red blood cells and plasma reduced and oxidized glutathione levels, glutathione peroxidase (GSH-Px) activity, thiobarbituric acid reactants (TBAR) of both chronic ambulatory peritoneal dialysis (CAPD) patients and a matched control group were investigated in this study. Oxidized and reduced pyridinic nucleotides in red blood cells (RBC), in which NADPH is a direct expression of hexose monophosphate shunt function, were also studied. The results obtained indicate that RBC and plasma are exposed to oxidative stress in CAPD. This condition is characterized by a decreased GSH/GSSG ratio, particularly evident in RBC as a consequence of the GSSG accumulation. Lipid peroxidation is increased, as indicated by raised TBAR levels, and reduced pyridinic nucleotides are decreased. Increased GSH-Px levels and unmodified or slightly increased GSH content were observed in the RBC but not in plasma, which showed decreased GSH and unmodified peroxidase activity. Peroxidase correlated positively with TBAR levels in the RBC lysates. In a subgroup of patients treated with erythropoietin (vs. untreated patients and controls) no differences were observed in the glutathione-related parameters studied. These data suggest that a mechanism for adaptation to oxidative conditions may be present in CAPD and its effects on RBC integrity are discussed in comparison with the hemodialysis conditions previously studied.

Selective trophic effect of L-carnitine in type I and IIa skeletal muscle fibers

Biopsies were taken from the vastus lateralis muscle of 26 chronic uremic patients before and after a 24-week treatment with L-carnitine given at the dose of 2 g i.v. at the end of hemodialysis, or in dialysis solution, or per os twice daily. The aim of the study was to evaluate both the muscle morphology in dialyzed subjects and the modification provoked by the therapy. All patients manifested a significant, even if variable, degree of muscular atrophy which involved all types of muscle fibers. After the treatment there was an increase of about 7% in the diameter of type I and type IIa fibers, which can utilize carnitine for fatty acid oxidation to produce energy, and a reduction in the atrophic fibers. No noteworthy changes were documented in type IIb fibers, which depend on glycolysis for energy production.

Changes in auditory P3 event-related potentials in uremic patients undergoing haemodialysis

A study on event-related P300 potential (ERPs) was performed in 20 patients suffering from chronic uraemia and undergoing haemodialysis in order to assessing the functioning of their cognitive processes. The patients were evaluated before and after a standard treatment of haemodialysis. The P300 potential was studied by means of the "oddball" paradigm and the acoustic modality. Moreover the patients' performance was assessed on the basis of the following psychological tests: the Mini Mental Test, the Number Connection Test and the Digit Span of the Wechsler Adult Intelligence Scale. A significant improvement in the P3 latency was demonstrated following the dialysis treatment. Even though a slight improvement in the N2-P3 deflexion amplitude was recorded after dialysis, it was not statistically significant. These data indicate a positive modification in the speed of the cortical function as a consequence of dialysis. These results suggest that the P3 latency obtained from auditory stimuli can help to assess the benefits obtained through extracorporeal dialysis, especially in the follow-up to the illness.

Renal funtional reserve in kidney transplant recipients

In the last few years different authors have observed that kidney transplant recipients with good organ function do not have a renal functional reserve (RFR). This condition is accompained by a high glomerular filtration rate (GFR). We studied RFR in patients with very good organ function under different immunosuppressive therapies, who were divided into groups based on the presence or absence of RFR.

Antibodies against hepatitis C virus in hemodialysis patients in the central Italian region of Umbria: evaluation of some risk factors

The epidemiology of non-A, non-B hepatitis (NANBH) is still incomplete. To define the prevalence of antibodies against the main causative agent of NANBH, the hepatitis C virus (HCV) and the role of some risk factors, we tested sera from 269 patients on chronic dialysis at the hemodialysis units in our region in central Italy. We utilized the recently developed serological assay. Twenty-nine hemodialysis patients (13.3%) and 3 peritoneal dialysis patients (4.8%) were anti-HCV positive. Of these, 13 (40.6%) had antibodies to hepatitis B core antigen (anti-HBc) indicating prior hepatitis B infection. The anti-HCV seropositive patients had been on dialysis longer than the seronegative ones; they had received more transfusions than the others but without a significant difference. The prevalence rate of anti-HCV was statistically significantly higher among hemodialysis patients utilizing the same dialysis equipment for the previous 12 months.

Autologous peritoneal mesothelial cell implant in rabbits and peritoneal dialysis patients

Human and rabbit peritoneal mesothelial cells have been successfully cultured and autoimplanted. An original biopsy technique was used to take samples of peritoneal mesothelial cells and after culture they were characterized from the structural and caryological points of view. Staphylococcal peritonitis was induced in 12 rabbits with indwelling peritoneal catheters and after 4 days of antibiotics 6 of them were autoimplanted with cultured autologous mesothelial cells previously marked in 3 cases with thymidine (H3TdR). Direct morphological observation and autoradiography were used to compare the mesothelium of control rabbits and implanted rabbits sacrificed on days 3 and 6 and showed that the cell implants had taken. Four uremic CAPD patients recovering from severe peritonitis were implanted with about 300 million autologous peritoneal mesothelial cells, previously cultured and frozen. Morphological signs of taking were evident from peritoneal laparoscopy biopsies performed 3 and 6 days after implant. The aim of the study was merely to demonstrate that such implants are possible; however, the techniques may have interesting applications not only in peritoneal dialysis, but also in the vaster fields of medicine and surgery.

Implant of autologous mesothelial cells in animals and a peritoneal dialysis patient

Success in culturing human and animal peritoneal mesothelial cells for the purpose of study, led us to determine whether these cells could be autoimplanted in animals and man during peritoneal dialysis in cases of acute and extensive loss of mesothelial surface area. Using an original biopsy technique, we were able to cultivate and characterize from the structural and caryological point of view, human and rabbit peritoneal mesothelial cells. Staphylococcal peritonitis was provoked in 12 rabbits with in-dwelling peritoneal catheters and after 4 days of antibiotic therapy, 6 of them were autoimplanted with cultured mesothelial cells. In the animals sacrificed on the third and sixth days, direct morphological observation and autoradiographic techniques showed that the transplanted cells had taken and revealed a different picture from that in the non-transplanted rabbits. In a 56 year old female diabetic patient, upon insertion of the first peritoneal catheter, a specimen of mesothelial cells was cultured and then frozen. Seven months later after an episode of peritonitis from candida which dictated removal of the peritoneal catheter, since there was a sufficient number of cultured mesothelial cells and the patient consented, the implant was performed. Peritoneal biopsy by laparoscopy three and six days later showed that the cells had taken. The purpose of the study was merely to show that autoimplant of mesothelium in man and animals is possible.

Thyroid function tests in patients undergoing maintenance dialysis: characterization of the 'low-T4 syndrome' in subjects on regular hemodialysis and continuous ambulatory peritoneal dialysis

Thyroid function tests were evaluated in 38 patients on regular hemodialysis (HD), in 36 on continuous ambulatory peritoneal dialysis (CAPD) and in 39 healthy controls. A significant reduction in total thyroxine (TT4), total triiodothyronine (TT3), reverse (rT3), and free T4 (fT4) mean levels and normal TSH, free T3, TBG and albumin concentrations was found in both HD and CAPD patients. A 'low-T4 syndrome' (serum T4 less than 5 micrograms/dl) was found in 9 CAPD (25%) and 20 HD (53%) patients, but none of them had fT4 levels below the normal laboratory range. The only striking difference between low-T4 HD and low-T4 CAPD patients was the significantly lower TBG and albumin serum levels in CAPD group. Low-T4 HD displayed normal TBG levels but enhanced fT4/TT4 and fT4/TT4 X TBG ratios. We concluded that: the abnormalities in thyroid function tests in patients on long-term dialysis (HD and CAPD) do not express the existence of a true hypothyroidism; a different pathogenesis of the low-T4 syndrome in the CAPD and HD groups may be hypothesized: in the former it could be attributed to a reduction in serum-binding capacity for thyroid hormones, in the latter the relative increase in fT4 percentage despite normal TBG levels suggests either the presence of T4-TBG-binding inhibitor(s), or structural abnormalities of thyroid-hormone-binding proteins.

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.

Biofiltration with buffer-free dialysate

The presence of acetate in the dialysate appears to be superfluous in the new depurative technique indicated as biofiltration, which consists in a standard hemodialysis with high ultrafiltration combined with the reinfusion of 3-4 1/2 liters of solution containing bicarbonate. The presence of acetate could in fact be contraindicated by a number of potential side effects, metabolic, cardiovascular and biological. Hence, starting from the consideration that in standard biofiltration a buffer is already infused directly as bicarbonate, we tried to overcome the potential hazards of the acetate-containing bath simply by using a dialysate without acetate and by increasing the concentration of bicarbonate in the reinfusate. A cumulative clinical experience of 20 months in 4 patients proved the feasibility and safety of the technique and suggests further advantages over standard biofiltration (better control of acid-base equilibrium, better cardiovascular stability.

Red blood cell membrane lipid peroxidation in continuous ambulatory peritoneal dialysis patients

We have recently described that in the erythrocytes from uremic patients on chronic hemodialysis, the pentose-phosphate shunt is defective, the membrane concentrations of malonyldialdehyde, resulting from peroxidation of polyunsaturated fatty acids in the membranes themselves, are increased, and the concentrations of vitamin E, an antioxidizing agent, are reduced. In the present study we have analyzed these same metabolic aspects in a group of uremic patients in continuous ambulatory peritoneal dialysis. We have found normal function of the pentose-phosphate shunt, slightly elevated concentrations of malonyldialdehyde compared to controls, but definitely lower than in chronic hemodialysis patients, and higher tocopherol concentrations than in both controls and chronic hemodialysis patients.

Phosphatidylcholine and peritoneal transport during peritoneal dialysis

Peritoneal effluent of patients on chronic ambulatory peritoneal dialysis (CAPD) contains a surface-active material (SAM) made up of phospholipids and showing phosphatidylcholine on thin-layer chromatography. This substance drastically lowers surface tension, helps to repel water and has a lubricating effect. The presence of stratified phosphatidylcholine on the peritoneum might narrow the stagnant dialysate fluid layer and situations which can alter the quantity or composition of SAM may affect peritoneal transport and also, perhaps, the formation of adherences. This led us to verify, experimentally, the presence of phospholipids in basal conditions, after CAPD and during peritonitis and to check if addition of phosphatidylcholine to dialysis liquid is able to modify water transport in patients with low ultrafiltration and peritonitis. Phospholipids in the dialysis effluent of patients who have been on CAPD for a long time are lower than observed in the first days of peritoneal dialysis. A more drastic, significant decrease in phospholipids was observed in patients with low ultrafiltration and in patients with peritonitis. Mean ultrafiltration significantly increases in patients with low ultrafiltration and in those with peritonitis during dialysis exchanges containing phosphatidylcholine (50 mg/l) indicating that the latter is able to restore normal physiological conditions.

Familial nephropathy with retinitis pigmentosa and closed-angle glaucoma

A renal syndrome with tapetoretinal degeneration and closed-angled glaucoma and transmitted in an autosomal dominant pattern is described. The precise classification of this syndrome is unclear but may represent a variant of Alport syndrome or nephronophthisis (Senior-Biochis syndrome).

Serum aluminum levels and peritoneal dialysis

Serum aluminum levels, significantly higher in dialysis patients than in normal subjects, were also found to be significantly higher in patients on PD than in those on HD. This could be related to a higher AI transport rate across membrane during PD than during HD. The easier contamination of PD dialysates and their acidic pH could account for this trend to a positive AI balance in PD. On the basis of our observations, however, the significance of the serum aluminum level could be very low, since aluminemia does not seem to reflect the cumulative amount of AI ingested and might not readily help predict the risk of AI intoxication.

Control of uremic neuropathy by equilibrium peritoneal dialysis

Motor nerve conduction velocity (MNCV), sensory nerve conduction velocity (SNVC) and distal motor latencies times (DMLT) were evaluated both in upper and lower limbs in three groups of 15 patients of comparable age, treated respectively by extracorporeal dialysis (HD), continuous ambulatory peritoneal dialysis (CAPD) and combined peritoneal dialysis (CPD) for comparable sufficiently long periods. Moreover, MNCV was monitored longitudinally in two groups of patients shifted from CAPD to HD and vice versa. The results show a significant superiority of peritoneal dialysis and particularly of CAPD with respect to HD in controlling uremic neuropathy.

Abnormal leucocyte locomotion induced by haemodialysis membranes. A clue to dialysis leucopenia

In a study on polymorphonuclear leucocyte (PMN) chemotaxis and random locomotion carried out on 16 patients undergoing haemodialysis and on the same functions in normal PMN which were separated from plasma and subjected to laboratory haemodialysis, it was shown that random PMN locomotion is reduced and that there is a concomitant fall in the leucocyte count in haemodialyzed patients. The laboratory haemodialysis demonstrated that serum factors were not responsible for the PMN dysfunction, which lasted for the entire period of the procedure. The changes were observed only when cellulose membranes were used, and not when haemodialysis was performed with polyacrilonitrile membranes. The reduction in random PMN locomotion may be involved in the genesis of dialysis leucopenia, as well as in the increased susceptibility of uremic patients to infections.

Autosterilizing CAPD connection systems

The reasons why the peritonitis rate in patients on CAPD with the traditional connection system remains unacceptably high are investigated and identified. In order to overcome such a highly limiting complication, a complete revision of the connection philosophy is suggested, substituting the exasperate prevention of the contamination with a simpler and more effective sterilization of the connection site after the connection has been made. Practical examples of chemical and thermal sterilization are illustrated.