PubMed Health⌕ Search

Biomedical subjects

G Colasanti

Publications and source records attributed to G Colasanti.

At least 19 recordsLinked to original sources
PubMed2000

Adequacy in hemodialysis: new concepts derived from online urea monitoring.

BACKGROUND: The estimation of urea kinetic parameters [urea generation rate (Gu), normalized protein catabolic rate (NPCR), and dialysis dose (Kt/V)] is routinely performed during a single hemodialysis session as a representative sample of a stable series. To ascertain whether the stability assumption is tenable and to estimate the variability of urea kinetic parameters, a number of stable patients on regular dialysis treatment in their usual clinical setting were followed. METHODS: Thirteen stable patients on regular hemodialysis aged 61 +/- 11 were monitored from 5 to 24 weeks (median, 10 weeks) with the urea biosensor system in double-chamber hemodiafiltration. Body weight did not change appreciably. Residual renal function was negligible or absent. Weekly averaged urea concentration (TACw), Gu, NPCR, and Kt/Veq were calculated, and their serial patterns and interrelationships were evaluated through graphical analysis and linear regression. RESULTS: In six patients, the urea pool was substantially unchanged, but variability of Gu and Kt/V was comparable to that of the other groups. In three patients, body urea pool increased. Gu went from 4. 78 +/- 0.44 to 5.40 +/- 0.65 mg/min, and Kt/V went from 1.25 +/- 0. 25 to 1.34 +/- 0.31. In four patients, body urea pool decreased; Gu went from to 6.55 +/- 1.91 to 5.85 +/- 2.26 mg/min, and Kt/V did not change appreciably. Parameters might change in a nearly linear trend or occasionally as abrupt or oscillating phases. Gu was the main factor involved, and the only one affecting four of the seven unstable patients. Kt/V was never solely involved. CONCLUSIONS: Our data indicate that the estimation of urea kinetic parameters is often affected by a non-negligible degree of variability, which can be ascribed to the variability of the dialytic dose delivered and, above all, to the daily changes of diet protein assumption.

Aged↗
PubMed1996

On-line urea kinetics in haemodiafiltration.

BACKGROUND: Calculation of Kt/V and assessment of nutrition have so far been dependent upon off-line urea measurements of blood or dialysate samples. Here we describe a biosensor for on-line urea measurement during haemodiafiltration. Methods. The biosensor consisted of a cartridge containing covalently linked urease placed between two conductivity cells. The biosensor was placed on the outlet line of a haemofilter in series with a dialyser in order to obtain an aliquot of plasma ultrafiltrate for on-line measurement of urea. RESULTS: Urea nitrogen concentrations were highly correlated to the difference (Delta) in conductivity measured by the two conductivity cells both in aqueous solutions (in-vitro studies, y=-6. 676+32.12x, R2=0.998, P<0.0001) and in ultrafiltrates (ex-vivo studies, y=-637+32.01x, R2=0.98, P<0.00001). Delta conductivity was highly reproducible (% variation: ).8-5.3%) and stable (maximal % variation at 150 mg/dl after 100 min. 0.9+/-0.3 vs initial values). The intradialytic plasma water urea profile was obtained in 10 haemodialysis patients. To study recirculation, the plasma water urea profile was analysed before and 3 min after stopping the dialysate flow. The pre- and post-stopped flow ratio (1.21+/-0.1, mean+/-1 SD) was superimposable to conventional blood sampling data (opposite arm venous arterial: 1.22+/-0.11) and allowed correction for recirculation. A novel approach to urea kinetic modelling was described and used to reliably project end-dialysis and post-dialysis rebound urea concentration as early as 90 min. Projected (29.2+/-10.4 g) or measured (29.8+/-10.5 g) net urea removal was highly correlated with the amount of urea collected in the total spent dialysate (29.7+/-10.6 g) (R2=0.99, R2=0.97 respectively). CONCLUSIONS: These results indicate that on-line, real-time analysis of urea kinetics may provide information on delivery of adequate dialysis in high-efficiency techniques.

Adult↗
PubMed1995

Long-term predictors of survival in essential mixed cryoglobulinemic glomerulonephritis.

We report the clinical outcome of 105 essential mixed cryoglobulinemia (EMC) patients with renal involvement collected throughout 25 years in three renal Units of Milan. The median follow-up was 72 months since renal biopsy and 131 months since the clinical onset of EMC. Patient survival was 49% at 10 years after renal biopsy. Forty-two patients died primarily from cardiovascular and liver disease or infection, whereas 15 patients developed chronic renal failure. Two patients had a complete remission of the disease while 15 had a remission only of renal signs. Thirty-one patients are alive with persistent renal and extrarenal manifestations. Anti-HCV antibodies were retrospectively detected in 34 patients and were present in 85% of them. This variable was not included in the statistical evaluation. At multivariate analysis, age older than 50 years, purpura, splenomegaly, cryocrit levels higher than 10%, C3 plasma levels lower than 54 mg/dl, and serum creatinine higher than 1.5 mg/dl were independent risk factors for death or dialysis. In conclusion, several factors may influence the outcome of patients with EMC nephritis. Markers of disease activity and an impaired renal function can herald a bad prognosis. It should be stressed, however, that only a minority of patients eventually develop renal failure, probably because in the most severe cases patients die earlier.

Adult↗
PubMed1995

Blood volume modeling and refilling rate estimation in hemodialysis by continuous hemoglobin monitoring.

Eleven bicarbonate hemodialyses (HD) of 6 patients under constant ultrafiltration were continuously monitored with an optical Hb-meter, considered to be a marker of blood volume (BV) changes. A theoretical model was fed experimental data for prediction of blood volume and estimation of vascular parameters, and a time course of rate of refilling was extrapolated. The adequacy of the model was very good for the time course of BV prediction (r2 = 0.85-0.95, n = 11) and for plasma protein concentration (r2 = 0.83-0.86, n = 2). Parameters estimated included (mean-DS): filtration coefficient (Cf) = 0.22 (0.16) dl/min*mmHg, transcapillary hydrostatic pressure (DP) = 17.80 (3.44) mmHg and protein concentration of the refilling fluid (Cref) = 0.45 (0.30) g/dl. In conclusion our study has shown that the model chosen fits the observed BV profile well in all cases, thus the Hb data series can be used for BV dynamic modeling and for estimation of vascular parameters.

Adult↗
PubMed1995

Biochemical aspects and clinical perspectives of continuous urea monitoring in plasma ultrafiltrate. Preliminary results of a multicenter study.

We tested a new biosensor for urea monitoring in the ultrafiltrate during PFD in a group of 5 hemodialyzed stable patients. The inspection of the UF-urea profile reflects the dynamical changes of the plasma urea concentration during diffusive dialysis and allows the fitting of the main mathematical models of urea kinetics. The biosensor efficiency was 98.4% on average (SD: 1.5%) at Uf fluxes varying from 45 to 55 ml/min (mean: 51 ml/min; SD: 3.2) and at Uf-urea concentrations varying from 23 to 165 mg/dl. The mean difference between Uf-urea determined by the laboratory method and Uf-urea assayed by the biosensor was -1.07 mg/dl and the 95% confidence interval ranged from -2.01 to 0.13 mg/dl. The mean difference between laboratory plasma urea and Uf-urea from the biosensor was on average -1.9 mg/dl and the estimated limits of agreement with a confidence of 95% were -3.16 and 0.64 mg/dl. Comparison between kinetic models and experimental profiles of plasma urea decrease, evaluations of recirculation and post-dialytic rebound, the role of Kt/V on-line during dialysis were the preliminary clinical applications of this biosensor.

Aged↗
PubMed1988

Characterization of interstitial infiltrating cells in Berger's disease.

The role of infiltrating blood-borne cells in the pathogenesis of renal damage in human glomerulonephritis is under active investigation. We have evaluated leukocyte infiltrates (number of cells/mm2) in the renal interstitium of 21 patients with Berger's disease and eight normal kidneys with monoclonal antibodies and a four-layer immunoperoxidase technique. In our population of patients, the number of infiltrating T-lymphocytes (OKT11+ cells) was significantly higher (median, 132) than in the normal kidneys (median, 60). This increase was mainly due to T-suppressor/cytotoxic lymphocytes (OKT8+ cells; median, 68), while T-helper/inducer lymphocytes (Leu 3A+ cells) and monocytes were in the normal range. T-lymphocyte infiltration was more marked in ten patients with impaired glomerular filtration rate (GFR) at the time of biopsy (median, 167) than in patients with normal GFR (median, 88). In addition, ten patients who showed deterioration of renal function during the subsequent follow-up, whatever their serum creatinine levels at the time of biopsy, had significantly more total T cells (median, 269), OKT8+ cells (median, 143), and Leu 3A+ cells (median, 105) than 11 patients with persistently stable GFR and normal controls. More data are necessary to establish whether this T-lymphocyte infiltration is the consequence of a cell-mediated mechanism acting in the interstitium, concomitant with the immune-complex-mediated mechanism acting in the glomerulus, or is a nonspecific consequence of the tubulointerstitial damage induced by the immunologically mediated glomerular disease.

Adult↗
PubMed1988

Food antigens, IgA-immune complexes and IgA mesangial nephropathy.

To investigate whether patients with IgA nephropathy have an exaggerated serum IgA response to ubiquitous food antigens we measured serum IgA antibodies to gliadin, ovalbumin, bovine serum albumin (BSA), beta-lactoglobulin and casein in 120 patients and 53 normal controls, using ELISA. No significant differences were observed between patients and controls in serum IgA antibodies against each of the antigens tested. Moreover, no correlation was found between serum IgA antibodies and IgA-immune complexes (IgA CIC). However, nine patients but no controls had an association of two or more IgA antibodies to dietary antigens. Sixty-six per cent of these patients (vs 24% in the remaining population) had IgA CIC, suggesting a possible involvement of these antibodies in the constitution of IgA CIC. Analysis of sera by HPLC revealed that both monomeric and higher molecular forms of IgA antibodies were present, the latter being coincident with the peak of IgA CIC. Preincubation of sera with serial concentrations of the specific antigen decreased significantly IgA CIC, suggesting that in this subgroup of patients IgA antibodies to food antigens (mainly BSA) are involved in the formation of IgA CIC. BSA-containing IgA CIC were in fact demonstrated by ELISA using rabbit IgG anti-BSA coated plates and peroxidase-conjugated anti-human IgA. The role of these CIC in the pathogenesis of IgA nephropathy needs to be further elucidated.

Adolescent↗
PubMed1988

The clinical significance of IgA rheumatoid factor in idiopathic IgA mesangial nephropathy (Berger's disease).

IgA rheumatoid factor, IgA and IgG immune complexes were measured in 119 patients with IgA nephropathy. IgA rheumatoid factor was detected in 62/119 (52%) patients and in 92/265 (35%) serum samples. There was a good correlation (p less than 0.001) between the presence of IgA rheumatoid factor and the presence as well as levels of IgG immune complexes, but not between levels of IgA rheumatoid factor and other clinical or immunological parameters. However, higher levels of serum IgA were found in the subgroup of patients with constantly positive IgA rheumatoid factor. Using aggregated human IgG, we could not demonstrate antiglobulin activity in renal biopsy specimens from 36 patients. These results suggest that IgA rheumatoid factor does not play a primary role in renal damage in IgA nephropathy, but could simply reflect a response to IgG immune complexes in a disorder characterized by abnormalities of IgA production. Nevertheless, the presence of circulating IgA rheumatoid factor in a substantial proportion of patients, especially in those with features of polyclonal IgA activation, provides additional evidence for a general perturbation of IgA metabolism in this disease and could represent an antigen-specific system with which to study regulation of IgA synthesis.

Adolescent↗
PubMed1987

Deposition of fibrin-stabilizing factor (F XIIIA and S), fibrinogen-related antigens, fibrinogen degradation products (FDPd and FDPe) and antihemolytic factor (F VIII) in renal disease: analysis of 161 cases by immunofluorescence microscopy.

To see whether or not the fibrin-stabilizing factor is involved in the pathogenesis of renal damage, we analyzed by IF the glomerular deposition of factor XIII (subunits A and S) in 161 patients with various renal diseases. In 4 out of 5 cases of thrombotic microangiopathy (80%), F XIII deposits were found in a continuous subendothelial pattern, in association with deposition of fibrinogen and FDP, suggesting the occurrence of intraglomerular coagulation. In 22 out of 45 patients with membranous GN (idiopathic or SLE-associated), F XIII deposits were found along the capillary walls in a subepithelial location. These findings were not correlated with the presence of particular histological or clinical features, nor with IF positive for fibrinogen, FDP and factor VIII, suggesting alternative pathways of fibrin formation or local collagen synthesis. Finally, in proliferative GN, either idiopathic (acute post-infectious and membranoproliferative) or systemic (SLE and vasculitis), as in other glomerular and non-glomerular diseases, the presence of F XIII deposits was negligible, even in cases positive for fibrinogen, FDP and factor VIII.

Antigens↗
PubMed1985

The detection of monocytes in human glomerulonephritis.

Renal biopsy specimens from 343 patients with primary or secondary glomerulonephritis (GN) were examined for monocytes by the non-specific esterase reaction. Large numbers of monocytes per glomerulus (M/G) were found in essential cryoglobulinemia GN (29 pts, M/G 30.6 +/- 22.4), in acute post-infectious GN (27 pts, M/G 9.1 +/- 8.3), in rapidly progressive crescentic GN (20 pts, M/G 5.6 +/- 2.7), in systemic lupus GN (61 pts, M/G 5.0 +/- 5.6), and in IgA-GN associated with chronic liver disease (5 pts, M/G 6.4 +/- 5.9) or Schönlein-Henoch purpura (15 pts, M/G 3.3 +/- 6.4). Clinico-histological correlation showed that monocyte infiltration was correlated with the extent of proteinuria (all groups), with the presence of endoluminal "thrombi" (cryoglobulinemia GN), of polymorphonuclear leukocyte infiltration (post-infectious GN), of cellular crescents (crescentic GN), of "active" lesions (lupus GN), and with the extension of lesions to the peripheral capillary walls (IgA-associated GN). The M/G index was negligible in renal amyloidosis (21 pts), in idiopathic membranoproliferative GN (10 pts), in idiopathic IgA mesangial GN (63 pts), in membranous GN (40 pts), in focal glomerulosclerosis (29 pts), in minimal change nephropathy (18 pts), and in diabetic glomerulosclerosis (5 pts). The results confirm the participation of cells of the monocyte-macrophage series in the genesis of proliferative lesions, both intracapillary and extracapillary, in immune-mediated human GN and suggest their direct involvement in glomerular injury.

Cryoglobulinemia↗