ALEX (artificial liver for extracorporeal xenoassistance): a new bioreactor containing a porcine autologous biomatrix as hepatocyte support. Preliminary results in an ex vivo experimental model

Long-term maintenance of viability and expression of differentiated hepatocyte function is crucial for bioartificial liver support. We developed a new bioreactor design (ALEX), associated with a new extracellular autologous hepatocyte biomatrix (Porcine Autologous Biomatrix - PBM) support. To test this new bioreactor, we compared it to a standard BAL (BioArtificial Liver) cartridge in a ex vivo model using human plasma added to bilirubin, ammonium and lidocaine. A pathology study was performed on both bioreactors. The results suggest that ALEX allows a maximal contact between the perfusing plasma and the liver cells and a proper hepatocyte support by a cell-to-matrix attachment. ALEX is a suitable cell support bioreactor, guaranteeing long-term maintenance of the metabolic activity of hepatocytes when compared to a standard BAL cartridge.

Beneficial effects of L-carnitine in dialysis patients with impaired left ventricular function: an observational study

BACKGROUND

Recent studies have shown that L-carnitine may improve clinical status and reduce the need for erythropoietin in dialysis patients with cardiovascular diseases. In this observational study, we investigated whether the addition of L-carnitine to conventional therapy might improve cardiac function (as assessed by M-mode and two-dimensional echocardiography) and clinical status in dialysis patients with left ventricular dysfunction.

METHODS

Eleven dialysis patients with reduced left ventricular function (EF < 45%) were treated with L-carnitine for 8 months. Two-dimensional (2-D) echocardiography was performed at baseline and every 2 months up to the end of the treatment period. The dosage of erythropoietin was also monitored during the study and the patients' clinical status was assessed by a questionnaire.

RESULTS

Carnitine increased mean LV ejection fraction from 32.0% to 41.8% (p < 0.05 vs baseline). There was also a slight reduction of erythropoietin dosage and an improvement of clinical status.

CONCLUSIONS

Eight months' therapy with carnitine appears to improve LV function and clinical status in dialysis patients with impaired LVF.

Liver-kidney-transplantation in type 1 primary hyperoxaluria: description and comments on a case

BACKGROUND

Primary hyperoxaluria leads to oxalosis, a systemic illness with fatal prognosis in uremic youngsters because of systemic complications.

CASE REPORT

A 14-year old boy with primary type 1 hyperoxaluria who had a long-lasting history of nephrolithiasis and passed from normal renal function to end-stage renal disease within 7 months. MEASUREMENT of alanine: glyoxylate aminotransferase (AGT) catalytic activity in the liver biopsy disclosed very low activity which was not. responsive to pyridoxin., thus the patient entered onto a priority national waiting list for liver-kidney transplantation and a week later received a combined transplant. In order to increase body clearance of oxalate, the patient underwent medical treatment to increase urine oxalate solubility (sodium and potassium citrate oral therapy, magnesium supplementation and increase of diuresis) and intensive dialysis both before and after transplantation.

COMMENT

The medical approach to the treatment of this rare illness is discussed. Since the major risk for the grafted kidney is related to the oxalate burden, i.e. oxalate deposition from the body deposits to the kidney that becomes irreversibly damaged, treatment consists of increasing the body clearance of oxalate both by increasing oxalate solubility in the urine and with intensive dialysis performed both before and after combined transplantation. To the same extent (by limiting body oxalate deposits), a relatively early (native GFR 20-25 ml/minute) transplantation is advisable.

Reduction of homocysteine levels in coronary artery disease by low-dose folic acid combined with vitamins B6 and B12

An increased plasma homocysteine concentration is a risk factor for atherosclerosis. Folic acid lowers homocysteine but the optimal dose in patients with coronary artery disease (CAD) is unclear. This placebo-controlled, single-blind, dose-ranging study evaluates the effect of low-dose folic acid on homocysteine levels in 95 patients aged 61 +/- 11 years (mean +/- SD) with documented CAD. Patients in each group were given either placebo or 1 of 3 daily supplements of folic acid (400 microg, 1 mg, or 5 mg) for 3 months. Each active treatment arm also received 500 microg vitamin B12 and 12.5 mg vitamin B6. Total plasma homocysteine levels were measured after 30 and 90 days. Folic acid 400 microg reduced homocysteine levels from 13.8 +/- 8.8 to 9.6 +/- 2.0 micromol/L at 90 days (p = 0.001). On 1- and 5-mg folic acid, levels decreased from 13.0 +/- 6.4 to 9.8 +/- 4.0 micromol/L (p = 0.001) and from 14.8 +/- 6.9 to 9.7 +/- 3.3 micromol/L (p < 0.001), respectively. The decrease was similar in all treatment groups. There was no significant change with placebo. Although the sample size is small, these findings suggest that daily administration of 400 microg/day folic acid combined with vitamin B12 and vitamin B6 may be equivalent to higher doses in reducing homocysteine levels in patients with CAD.

The effect of metabolic control on development and progression of diabetic nephropathy

The progressively growing number of patients with end-stage renal failure (ESRF) associated with diabetes mellitus and requiring renal replacement therapy (RRT) stimulated both nephrologists and diabetologists to investigate the mechanisms linking hyperglycaemia to diabetic renal failure and to set up measures to prevent the onset and slow the progression of diabetic nephropathy. Over the last few decades, a large number of studies have investigated both the incidence of diabetic nephropathy and the relationship between metabolic control and the development of diabetic nephropathy. Chronologically, the first type of diabetes and diabetic nephropathy to be studied was type I, and it is only in recent years that metabolic control has been proven to be a contributor to the development of nephropathy in such patients. Recently, the DCCT demonstrated that metabolic control in the prealbuminuric phase was effective in reducing the incidence of microalbuminuria, even if it was unable to reduce the incidence of overt proteinuria in patients with type I diabetes and established proteinuria. On the other hand, in type II diabetes, the number of studies demonstrating a favourable effect of metabolic control on onset and progression of diabetic nephropathy is only slightly greater than those that failed to show a favourable effect. This feature may suggest that in type II patients, genetic and ethnic differences, nutritional aspects, lifestyle and other confounding factors may play a relevant role in the course of the disease. However, the trials performed and the retrospective analyses generally agree that glycated haemoglobin two standard deviations greater than the mean is related to a worsening in progression of diabetic nephropathy and to an enhanced risk of other complications. In general, a glycated haemoglobin < or =8% seems advisable. Moreover, in both type I and type II, greater emphasis should be placed on the major risk factors such as hypertension, smoking habits and hyperlipidaemia.

Short-term outcome of diabetic patients in renal replacement therapy

BACKGROUND

Diabetic nephropathy or diabetes-related nephropathies represents one of the most relevant causes of renal failure in recent years. This complex pathological picture becomes particularly severe as time elapses and after starting renal replacement therapy (RRT).

METHODS

In an attempt to investigate the evolution of the major clinical features, a retrospective study was carried out on a cohort of 76 diabetic patients on RRT. Sixty-five have been treated by haemodialysis (HD) and 11 by peritoneal dialysis (CAPD), for at least 1 year. In these patients change in modality of treatment, metabolic control, cardiovascular, and ophthalmological complications, peripheral neuropathy, state of vascular access, and intradialytic complications were surveyed at initiation and after 1 year of treatment. A modified Karnofski's score was utilized, to evaluate the degree of rehabilitation. The comparison of prevalence was evaluated, using Student's t-test for paired samples.

RESULTS

After 1 year, 11 patients on CAPD remained on the same type of treatment. Out of 65 patients on standard bicarbonate HD, 11 were moved to acetate free biofiltration, two to paired filtration dialysis and one to haemofiltration. A worsening in arrhythmias was recorded with an increased prevalence from 25.0 to 35.0% (n.s.), and one more patient (15 vs 16 and 19 vs 20 respectively) experienced ischaemic cardiomyopathy and cerebrovascular insufficiency. Hypertension showed a significant improvement (72 vs 42, P<0.01). Nausea and vomiting, hypotensive episodes, and muscular cramps were more frequently observed. A worsening in patient's welfare was also recorded but without statistical significance.

CONCLUSIONS

This clinical evaluation even if retrospective and lasting 1 year, may suggest that RRT does not per se represent a cause of the development and progression of the major complications related to diabetic disease.

Prospective study of hyperhomocysteinemia as an adverse cardiovascular risk factor in end-stage renal disease

BACKGROUND

Retrospective and case-control studies show that hyperhomocysteinemia is an independent risk factor for atherosclerosis in patients with end-stage renal disease. We studied prospectively the association between total homocysteine and cardiovascular outcomes.

METHODS AND RESULTS

In all, 167 patients (93 men, 74 women; mean age, 56.3+/-14.7 years) were followed for a mean duration of 17.4+/-6.4 months. Cardiovascular events and causes of mortality were related to total homocysteine values and other cardiovascular risk factors. Cox regression analysis was used to identify the independent predictors for cardiovascular events and mortality. Fifty-five patients (33%) developed cardiovascular events and 31 (19%) died, 12 (8%) of cardiovascular causes. Total plasma homocysteine values ranged between 7.9 and 315.0 micromol/L. Levels were higher in patients who had cardiovascular events or died of cardiovascular causes (43.0+/-48.6 versus 26.9+/-14.9 micromol/L, P=.02). The relative risk (RR) for cardiovascular events, including death, increased 1% per micromol/L increase in total homocysteine concentration (RR, 1.01; CI, 1.00 to 1.01; P=.01).

CONCLUSIONS

These prospective observations confirm that hyperhomocysteinemia is an independent risk factor for cardiovascular morbidity and mortality in end-stage renal disease, with an increased RR of 1% per micromol/L increase in total homocysteine concentration. Interventional studies are needed to evaluate the possible effects of modifying this risk factor in these patients.

[Relationship between late ventricular potentials and ventricular arrhythmias in patients in chronic dialysis treatment]

BACKGROUND

Arrhythmias are frequent pathology in patients with chronic hemodialysis. We evaluated whether a relatively new technique, signal averaging, could be useful in predicting the development of complex arrhythmias in these patients.

METHODS

Thirty-three patients, 18 male and 15 female, subjected to thrice weekly chronic hemodialytic treatment with various dialysis techniques, were studied. Exclusion criteria were the presence of antiarrhythmic and inotropic treatment. The following examinations were carried out in all patients: a Holter dynamic electrocardiography for a duration of 24 hours, begun on the day of dialysis, high resolution ECG pre- and post-dialysis to find out if there were any ventricular late potential (VLP). Four hundred beats were examined in order to obtain a background noise of less than 0.7 microV and a better definition of the signal. The following parameters were considered significant for the presence of VLP: a) filtered QRS duration > 120 msec; b) the root mean square of the signal expressed in the terminal portion of QRS (RMS) < 25 microV) high frequency low amplitude signals duration (HFLA) > 40 msec. A positive value in two of these parameters was considered indicative of the presence of VLP. In addition various pre and post-dialysis indices of dialytic efficiency and a mono and two-dimensional echocardiogram with pulsed and color Doppler were carried out. Of the 33 patients studied, ten were excluded because they presented too high a background noise at the high resolution ECG. Of the remaining 23 patients, 13 (56%) presented VLP and nine of these (69%) presented complex arrhythmias. Of the ten patients without VLP, 5 (50%) presented complex arrhythmias. The incidence of arrhythmias was highest during the last two hours of dialysis and in the two hours following it. The patients were then divided into two groups (A and B) according to the ejection fraction (EF) found at the echocardiogram. Group A was composed of 17 patients of whom 8 (47%) presented complex arrhythmias; group B (EF < 45%) was composed of the remaining six patients, who all presented complex arrhythmias. In group A nine patients (53%) out of 17 had LVP, in group B four out of six (66%) had it. All the patients except one presented an increase in the thickness of the ventricular wall and alterations of Doppler transmitral filling rate. Left ventricular hypertrophy was diagnosed in 22 out of the 23 patients. Four patients also had chronic ischaemic heart disease; of these three had LVP. There was no correlation between the presence of LVP and the hemodialytic indices and between the latter and complex arrhythmias.

CONCLUSIONS

Our study showed that arrhythmias are more frequent in patients with LVP before dialysis than in those without. The difference was statistically significant (p < 0.006); the incidence of arrhythmias was higher in patients with FE < 45% (p < 0.001). The majority of patients (95%) had left ventricular hypertrophy; only four (17%) had ischaemic heart disease too. It is highly probable that the presence of LVP in our patients can be attributed to hypertension and subsequent left ventricular hypertrophy. As patients with LVP at the end of dialysis had a greater incidence of arrhythmias than those without LVP, we suggest that this method could be useful as a first screening in dialysed patients.

Tissue factor pathway inhibitor (TFPI) activity in uremic patients during hemodialysis

We studied tissue factor pathway inhibitor (TFPI) activity during hemodialysis in 10 uremic patients who were not receiving anticoagulant for at least 120 minutes. TFPI activity before dialysis was normal (patients 107 +/- 5.8%, controls 104 +/- 4.5%). During extracorporeal circuit it rose progressively with a statistically significant difference, reaching a plateau between 60 and 120 minutes. Since thrombin induces a marked redistribution and release of TFPI from stimulated endothelial cells and platelets contain about 10% of TFPI activity that is secreted following activation it is possible that thrombin-induced release of TFPI by endothelium and platelets could account for the increased TFPI we found during hemodialysis. To investigate this possibility we measured during dialysis beta-thromboglobulin (beta-TG), thrombin-antithrombin complex (TAT) and prothrombin fragment 1.2 (F 1.2). The increased levels of beta-TG, TAT and F1.2 we noted during extracorporeal circuit are in keeping with this concept. One hundred eighty minutes after initiation of dialysis, by which time all patients were receiving heparin there was a further increase in TFPI (to more than 200% of baseline), due to the presence of the glycosaminoglycan. This was due the previously reported displacement by heparin of the major intravascular pool of TFPI, from endothelial cell surfaces.

Nitric oxide synthase in chick embryo retina during development

High levels of nitric oxide synthase were found in the early stages of developing chick embryo retina. The enzyme activity sharply decreased up to 13-day-old chick embryo retina, when the level of the last embryonic day was reached. The results show that nitric oxide is synthesized in chick embryo retina prior to synaptogenesis. The incubation of chick embryo retinas in presence of NMDA increased the synthesis of nitric oxide, thus, the appearance of nitric oxide production before the synaptogenesis in the retina as well as in the brain may be considered as signal for the development and shaping of neuronal and non-neuronal cells.

[Study of the arrhythmia in patients with chronic uremia in periodic hemodialysis with Holter dynamic electrocardiography]

For the purpose of evaluating cause, frequency, type and seriousness of arrhythmias in dialysis patients, 14 chronic uremics, 8 on bicarbonate-dialysis, 6 on acetate-dialysis underwent a basal ECG, echocardiography and a Holter dynamic electrocardiography (ECGD) for a duration of 96 hours. Before and after dialysis PAO, body weight, serum electrolytes and arterial pH were controlled. In 11 patients (78%) supraventricular and ventricular arrhythmias were discovered of equal frequency and seriousness both in the inter and intra dialytic phase, even if more frequent in ventricular hypertrophic patients (IVSn) the complex ventricular arrhythmias (Lown greater than 2). The seriousness and frequency of ventricular and supraventricular arrhythmias in the dialytic phase did not seem to depend either on the type of tampon or on the presence or absence of cardiopathies while in the inter-dialytic phase the seriousness of ventricular arrhythmias seems to depend upon the presence of cardiopathies. The Authors conclude that the pathogenesis of arrhythmias in uremic patients on dialysis is multifactorial and that their elevated incidence makes the use of a Holter in these patients recommendable.

Biofiltration vs. bicarbonate dialysis: influence on plasma volume changes and extravascular fluid mobilization

The present study compares the effects of bicarbonate hemodialysis (Bic. HD) and biofiltration (BF), a new hemodiafiltration technique, on plasma volume (PV) changes and extravascular fluid mobilization (Vfm). Ten uremic patients underwent one experimental session of Bic. HD and, one week later, one of BF, both on the second dialysis of the week. Net ultrafiltration rate was limited to 700 ml/min. At the start of each session, whole blood volume (WBV), PV and red cell volume (RCV) were determined using 5 mu Ci of radioiodinated serum albumin (RISA). PV and Vfm were calculated at hourly intervals using a serial hematocrit method. On Bic. HD, PV increased at 60 min. then decreased at 120 and 180 min., with efficient Vfm only during the first hour. On BF, PV increased throughout treatment, with greater Vfm. It would appear that PV is better preserved in BF, on account of more efficient Vfm.

Carnitine deficiency induced during hemodialysis and hyperlipidemia: effect of replacement therapy

Plasma carnitine levels were studied in 14 uremic patients before, during, and after hemodialysis. The predialysis plasma carnitine levels were normal but fell during dialysis (half-life of 3.6 h). Plasma carnitine levels rose quickly in the first 6 h after dialysis, after which time the rise was more gradual. Muscle carnitine was significantly reduced in the dialyzed patients (p less than 0.005) compared with controls. In four patients lipid droplets were observed in muscle. Ten patients on maintenance hemodialysis exhibited plasma hyperlipidemia and low muscle carnitine. These individuals were given DL-carnitine (50 mg/kg body weight) intravenously after each dialysis. At the end of a 2-month carnitine treatment, plasma triglyceride levels were found to be reduced (p less than 0.001) and muscle carnitine content significantly increased (p less than 0.005). These findings suggest that carnitine may be useful in treatment of hypertriglyceridemia and muscle carnitine deficiency states induced during maintenance hemodialysis.