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Biomedical subjects

F Pizzarelli

Publications and source records attributed to F Pizzarelli.

At least 19 recordsLinked to original sources
PubMed2006

Clinical pathological correlates of renal biopsy in elderly patients.

BACKGROUND: Reports have shown that well-defined histological patterns do not always correspond to equally clear clinical pictures, particularly so in elderly patients. METHODS: With the aim of assessing clinicopathological correlations in the population aged >65 years with that of lower age, we retrospectively analyzed computerized records of renal needle biopsies consecutively performed in the decade 1991-2000 in our unit. RESULTS: Among the 392 eligible subjects, there were 150 patients 65 years of age and more, 76 of whom were over 70. The average serum creatinine was 2.9 mg/dl, with values > 3.5 mg/dl in 25% of cases. The major indication to biopsy was nephrotic syndrome followed by chronic renal failure both in the young adult and the elderly population. The rapidly progressive form led more often to renal biopsy in the elderly patients, and the different prevalence was statistically significant (p < 0.05), as was the higher prevalence of urinary anomalies in the young-adult population. Regarding renal histology, the crescentic necrotizing forms were significantly more frequent in the elderly patients, while IgAN, minimal change disease and SLE predominate in young adults. The most relevant result is the greater prevalence of crescentic necrotizing glomerulonephritis in elderly patients, not only in the cases presenting clinically as rapidly progressive renal failure and acute renal failure, but also in those with the clinical picture of chronic renal failure. CONCLUSIONS: Re-evaluation of our case files verifies the importance of the bioptic approach in selected cases with stages 3-4 chronic kidney damage. This holds true especially for elderly patients.

Adult↗
PubMed2001

Cellular interleukin-1 receptor antagonist production in patients receiving on-line haemodiafiltration therapy.

BACKGROUND: Repetitive exposure to cytokine-inducing substances (pyrogens) results in chronic inflammation, which may significantly contribute to some of the long-term complications in dialysis patients. On-line dialysis modalities, such as on-line haemodiafiltration (HDF), raise particular concerns because of the administration of infusate prepared from potentially contaminated dialysis fluid. Hence, great retention capability for pyrogens is of critical importance for the safe performance of on-line systems. METHODS: The microbiological safety of a novel on-line system, ONLINEplus(TM), was assessed in clinical practice in five centres for 3 months. Infusate and dialysis fluid were regularly monitored for microbial counts, endotoxins, and cytokine-inducing activity. Levels of interleukin-1 receptor antagonist (IL-1Ra) were determined in supernatants of whole blood incubated either under pyrogen-free conditions (spontaneous cytokine production) or following low-dose endotoxin exposure (LPS-stimulated cytokine production). RESULTS: We failed to detect microorganisms or endotoxin contamination of infusate during the entire study period. Moreover, neither infusate nor dialysis fluid demonstrated cytokine-inducing activity. Intradialytic IL-1Ra induction was not detected, as there was no difference between pre- and post-session values for both spontaneous and LPS-stimulated IL-1Ra production (115+/-26 vs 119+/-27 and 2445+/-353 vs 2724+/-362 pg/10(6) white blood cells (WBC), respectively). Neither the number of immunocompetent cells nor their capacity to produce IL-1Ra declined during this period, indicating that cells were not significantly stimulated during treatment. Spontaneous and LPS-induced exvivo IL-1Ra generation remained unchanged after 3 months of on-line HDF therapy as compared with the start of the study (71+/-30 pre- vs 48+/-14 post-study, and 2559+/-811 vs 2384+/-744 pg/10(6) WBC, respectively). CONCLUSIONS: The present on-line system performed safely from a microbiological view-point as both the dialysis fluid and infusate were consistently free of microorganisms, endotoxins, and cytokine-inducing substances. As a result, on-line HDF therapy had no effect upon the chronic inflammatory responses in end-stage renal disease patients.

Adult↗
PubMed2000

Cardiovascular stability during haemodialysis, haemofiltration and haemodiafiltration.

Several comparative studies have claimed that procedures based substantially or exclusively on pressure-driven water-solute transport, such as haemodiafiltration or haemofiltration, afford better protection of the cardiovascular tolerance to fluid removal than conventional haemodialysis. During each depurative modality, several factors are set in motion that might impact, each in its own right, upon the haemodynamic response to fluid withdrawal. To explore the haemodynamic effect of each of them singularly, one needs to keep all other components unvaried. However, this is very difficult to accomplish. For instance, to confirm the alleged greater protection of cardiovascular stability by pure convection vs diffusion, one needs to keep unvaried all the other factors potentially affecting haemodynamic tolerance, i.e. the rate of body fluid removal, the membrane, the buffer, the blood temperature in the extracorporeal circuit, depuration efficiency, the sodium balance, the fluid sterility and so on. Such studies are still awaited. However, clinical trials published to date have not resolved the question of whether haemofiltration and haemodiafiltration provide a better haemodynamic tolerance to fluid removal. If we limit our consideration to controlled trials only, most prospective studies have adopted a cross-over design implemented on very small patient samples and for very short periods. Such an approach is liable to generate misleading results because the incidence of dialysis hypotension often fluctuates from time to time. Owing to such fluctuations, results can be strongly affected by the 'order effect' of the cross-over from one technique to the other. The negative results provided by parallel comparisons of procedures should be taken with caution because patients samples did not include a suitable proportion of unstable patients.

Cardiovascular System↗
PubMed2000

Double-chamber on-line hemodiafiltration: a novel technique with intra-treatment monitoring of dialysate ultrafilter integrity.

On-line hemodiafiltration is a technique that relies on the re-injection of pyrogen-free substitution fluid obtained by cold filtration of dialysate. Therefore, safety of this treatment modality depends on the quality of dialysate and, mainly, on the integrity of the ultrafilter(s) employed. Double-chamber on-line hemodiafiltration is a new technique where re-infusion takes place inside the dialyser by means of dialysate backfiltration. The peculiar geometry of the dialyser allows intra-treatment assessment of its fibre integrity. In this paper, we tested feasibility and safety of this new modality of on-line treatment. The extracorporeal blood and infusate pressure values resulted well inside the safety range. Blood urea clearances and beta(2) removal were consistent with the figures usually found in standard hemodiafiltration. Whole blood production of cytokines was similar when blood was exposed to saline or infusate, both values being comparable to the spontaneous whole blood cytokine release. The on-line dialyser fibre integrity check showed a great sensitivity even for minimal dialyser damage. We conclude that double-chamber on-line hemodiafiltration is a feasible and safe procedure. Our preliminary results encourage the undertaking of multicentre, prospective, randomised studies.

Consumer Product Safety↗
PubMed1998

Convective treatments with on-line production of replacement fluid: a clinical experience lasting 6 years.

BACKGROUND: The introduction of techniques with on-line (OL) production of replacement fluid by filtration of dialysis fluid raises concerns about exposure of dialysis patients to pyrogenic substances. This work was undertaken to evaluate safety and feasibility of OL preparation of replacement fluid for haemodiafiltration (HDF). METHODS: OL HDF was carried out with commercially available monitors without any adjustment in the operational organization of our Centre. Bicarbonate dialysis fluid was filtered twice before being reinjected into the patients. The effects of acute load of OL fluid were assessed by very sensitive in vitro and in vivo tests; the chronic effects were assessed by monitoring the patients for the appearance of any untoward clinical manifestations and by measuring their cytokine response. RESULTS: In a pilot study the membrane filter culture technique of replacement fluid yielded no bacteria or mycetes growth, while LAL test was < 0.01 EU/ml. The normal human monocyte production of TNF alpha, IL-1 beta and IL-1Ra was not significantly different when cells were incubated with OL or commercial replacement fluid. The patients' body temperature profile (continuous recording during treatments and the following 24 h) overlapped with that of the control procedure. Over 6 years we performed 4284 OL treatments (total amount reinjected fluid 102,900 litres) on 13 patients treated for 26 +/- 9 months. In none of these treatments did we observe pyrogenic reactions. In comparison with the previous period on standard bicarbonate haemodialysis, OL HDF afforded significantly better cardiovascular tolerance to fluid removal and higher Kt/V values. The nutritional status did not deteriorate, while the acute-phase reactants and serum beta 2M levels did not increase. Moreover, no translucent cysts or destructive arthropathy were observed on bone X-rays. The patients' plasma cytokine levels and monocytes cytokines production, measured either before or after a single OL HDF, were comparable with the values obtained in controls treated with standard HDF. CONCLUSIONS: We conclude that OL-prepared replacement fluid is as safe as that of the commercial bags with regard to sterility and non-pyrogenicity. OL HDF can be readily implemented in any dialysis centre without bringing any further burden on the staff.

Adult↗
PubMed1995

Non-invasive monitoring of hemodynamic parameters during hemodialysis.

We studied in 13 hemodialysis patients intradialytic variations of blood volume (BV) and cardiac output, by means of non-invasive methods. We found a weak correlation, r 0.2 or less, between BV variations and intradialysis blood pressure variations. The sensitivity of the former in describing the variations of the latter was only 32%. During the 30 min preceeding the hypothensive crisis the percent BV variations did not show any predictive trend. On the contrary, refilling increased as blood pressure dropped and a weak inverse relation (r -0.35) was found between these two parameters. Unstable patients had predialytic blood volume values significantly lower than stable ones and comparable to healthy subjects. On the contrary, the correlation between percent variations of cardiac output index and MAP was 0.68 with a sensitivity and specificity of 90% and 59%, respectively. Unfortunately these promising results were obtained only with an estimate of cardiac output obtained by echocardiography and not by transthoracic impedance cardiography, which is much more feasible than the former as on-line monitoring of cardiac output. On-line monitoring of hemodynamic parameters is an appealing but still unsolved task.

Aged↗
PubMed1995

Thermal balance and dialysis hypotension.

Many studies have confirmed our original observation that dialysate T set at about 35 degrees C affords a better hemodynamic protection than the standard dialysate T of 37-38 degrees C. In this review we present some new data on the hemodynamic mechanism of the protective effect of cold dialysis on blood pressure. The study was based on serial assessment of the percent changes occurring during dialysis treatment in estimated stroke volume (aortic blood flow determined by Doppler echocardiography), blood volume (hemoglobinometry), arterial pressure (Dynamap), and heart rate (ECG), from which cardiac output (CO) indexes and total peripheral vascular resistances (TPVR) were derived. Of the 14 pts studied, 7 showed a drop in mean arterial pressure (MAP) of 25% or greater during standard dialysis (unstable patients). Compared with the 7 patients having more stable intradialysis MAP, unstable pts showed greater reduction in CO which was disproportionately greater than the reduction in blood volume, and a paradoxical decrease in TPVR, the difference being highly significant (p < 0.01 for both changes). When crossed-over to cold dialysis, along with a significantly lower reduction in MAP (p < 0.01) the unstable pts showed a lower decrease in CO which paralleled the reduction in blood volume, and an increase in TPVR. These changes were highly significant (p < 0.01). Data suggest that dialysis hypotension is characterized by an impaired venous return, probably due to the peripheral blood pooling (increased ratio between the 'unstressed' and 'stressed' blood volume) associated with the decrease in TPVR. Exposure of extracorporeal blood to cold dialysate favours the venous return to the heart by increasing TPVR and the 'stressed' blood volume.

Blood Pressure↗
PubMed1993

Parathyroidectomy and blood pressure in hemodialysis patients.

To assess whether parathyroidectomy (PTx) affects blood pressure (BP) in hemodialysis (HD) patients, we studied 11 uremics on HD treatment for 8.2 +/- 0.9 years who underwent successful PTx. As the control group, we selected 11 HD patients not submitted to PTx, matched with the study group for sex, age, years on HD, dialysis procedure and BP values. In the controls, BP and body weight did not change during the 2 years of observation. In the patients, BP remained stable in the year before PTx. PTx caused a progressive reduction in BP in 7 of the 11 patients. The fall was significant from the 3rd quarter onward (mean BP values before PTx: 139/82 mm Hg, 1 year after PTx: 122/75 mm Hg). The magnitude of the hypotensive effect of PTx was related to the pre-PTx systolic BP value (r = -0.70, p = 0.016). PTx also caused a significant progressive increase in body weight (1.56 +/- 0.57 kg 1 year after PTx). In conclusion, PTx causes BP fall in HD patients regardless of whether their preintervention values are normal or increased. The BP reduction occurs in concomitance with a consistent increase in body weight. BP variations are clinically relevant and may be related to the post-PTx calcium efflux from the vessel wall.

Alkaline Phosphatase↗
PubMed1992

Hepatitis B vaccination in dialysis patients and nutritional status.

35 dialysis patients underwent anti-HBV vaccination. We classified patients in responders or non-responders using an anti-HBs titer of 50 UI/l as the discriminating serum level and tried to assess whether the antibody response bears any relationship with the nutritional status. 26 patients (74%) reached the target atb titer, which was maintained during follow-up (average 360 UI/l). The weak response in the other 9, with values never exceeding 20 UI/l, was short-lived. Anthropometric and impedenziometric parameters were higher in responders than in nonresponders, but the difference did not reach statistical significance. We conclude that the atb titer which discriminates uremics in responders or not must be greater than 50 UI/l and that the nutritional status may interfere with the seroconversion rate, but this conclusion needs to be validated in a wider population.

Adult↗
PubMed1988

Aluminum bone content in dialysis osteodystrophy with secondary hyperparathyroidism.

To assess whether parathyroid hormone (PTH) has any effect on bone aluminium (A1) accumulation, we evaluated the relationship between bone quantitative histomorphometry and bone A1 content in 25 dialysis patients with clinical features of secondary hyperparathyroidism. By means of bone biopsy, patients were classified as showing predominant hyperparathyroidism in 17 cases and mixed lesions in 8. The A1 burden was low, judging from the dialysate A1 and the oral A1 assumption. Bone A1 content and serum A1 levels were higher than normal in both groups, particularly so in the patients with predominant hyperparathyroidism. Significant positive correlations were found between bone indexes of hyperparathyroidism and bone A1 content. Moreover, bone and serum A1 concentrations were directly related. Aluminium staining appeared faintly positive only in a minority of bone samples, and was mainly localized at the neutral bone surfaces. We conclude that in dialysis osteodystrophies with features of secondary hyperparathyroidism and in a clinical setting characterized by low-grade A1 burden, PTH may favour A1 accumulation into the bone.

Adult↗
PubMed1987

Effect of chronic administration of ammonium sulfate on phosphatic stone recurrence.

Urine alkalinization favours the formation of calcium phosphate (CaP) and struvite stones. In this retrospective study we analyze the effect of chronic urinary acidification on phosphatic stone recurrence. Twenty-four patients with CaP-struvite recurrent stones and persistently high urinary pH were divided in two groups: group A, 11 patients who failed to lower the urinary pH below 5.5 during a standard acid load test: group B, 13 patients with preserved acidification power. Ammonium sulfate 2-3 g/day was given for 4.7 and 6.5 years to groups A and B, respectively. A persistent reduction in urinary pH, relative saturation for CaP and stone formation rate was observed in both groups. The treatment did not cause systemic acidosis as long as renal function remained normal. Urinary daily excretion of Ca and P as well as their renal tubular handling did not change with time. Results suggest acidifying agents might be useful in preventing recurrence of CaP-struvite stones even in the presence of a mild acidification defect and encourage undertaking properly controlled prospective trials.

Adult↗