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Biomedical subjects

C Castelnovo

Publications and source records attributed to C Castelnovo.

At least 19 recordsLinked to original sources
PubMed2002

Fractal analysis of sampled profiles: systematic study.

A quantitative evaluation of the influence of sampling on the numerical fractal analysis of experimental profiles is of critical importance. Although this aspect has been widely recognized, a systematic analysis of the sampling influence is still lacking. Here we present the results of a systematic analysis of synthetic self-affine profiles in order to clarify the consequences of the application of a poor sampling (up to 1000 points) typical of scanning probe microscopy for the characterization of real interfaces and surfaces. We interpret our results in terms of a deviation and a dispersion of the measured exponent with respect to the "true" one. Both the deviation and the dispersion have always been disregarded in the experimental literature, and this can be very misleading if results obtained from poorly sampled images are presented. We provide reasonable arguments to assess the universality of these effects and propose an empirical method to take them into account. We show that it is possible to correct the deviation of the measured Hurst exponent from the "true" one and give a reasonable estimate of the dispersion error. The last estimate is particularly important in the experimental results since it is an intrinsic error that depends only on the number of sampling points and can easily overwhelm the statistical error. Finally, we test our empirical method calculating the Hurst exponent for the well-known 1+1 dimensional directed percolation profiles, with a 512-point sampling.

Journal Article↗
PubMed1998

Peritoneal dialysis in nondiabetic patients older than 70 years: comparison with patients aged 40 to 60 years.

In all industrial countries, the number of elderly patients who need dialysis has increased in recent years. In the present study, we retrospectively analyzed two different age groups of nondiabetic peritoneal dialysis patients treated at the same unit by the same team of physicians and nurses with the same protocols. However, our purpose was to study possible differences in technique and survival rates, causes of dropout, complications, hospitalization rate, and everyday needs between the two groups. The results of 63 consecutive nondiabetic patients older than 70 years treated with continuous ambulatory peritoneal dialysis (CAPD) were compared with those of 86 nondiabetic patients aged 40 to 60 years treated during the same period. Patient survival was significantly worse in the elderly patients, but the observed to expected survival ratio with respect to age was similar. Technique survival was comparable in the two groups. Total hospitalization was 5,501 days (32 d/yr) in the elderly patients and 4,511 days (18 d/yr; P < 0.05) in the younger group. The peritonitis rate was 0.52 episodes/patient-year in the elderly patients and 0.37 episodes/patient-year in the younger patients (P < 0.002). The exit site infection rate was similar in the two groups (0.30 episodes/yr v0.29 episodes/yr). Other complications related to CAPD did not differ between the elderly and younger patients. Rehabilitation and biochemical data after 1 year of CAPD were similar in the two groups of patients. After 1 year of treatment, 12% of the younger patients and 43% of the elderly patients (P < 0.005) needed a partner for dialysis. Twenty-nine of 39 (74%) of the elderly patients and 30 of 53 (57%) of the younger patients considered their lifestyle acceptable after 1 year of dialysis. Thirty-four of 39 (87%) of the elderly patients and 32 of 53 (60%) of the younger patients (P < 0.02) rated their physical and social state after rehabilitation as better or comparable to that they had before terminal uremia.

Adult↗
PubMed1997

Diffusion of HCV through peritoneal membrane in HCV positive patients treated with continuous ambulatory peritoneal dialysis.

PURPOSE OF THE STUDY: We evaluated the presence of HCV in the peritoneal effluents of viraemic patients treated with continuous ambulatory peritoneal dialysis (CAPD) to evaluate the risk of transmitting the infection with this procedure. PROCEDURE: Fifteen of 81 CAPD patients (18.5%) had anti-HCV antibodies and eight were viraemic. At the beginning of CAPD two of the viraemic patients had ascites with a clinical picture of chronic active hepatitis and cirrhosis. Peritoneal dialysates were collected after an overnight exchange with 1.36% glucose and after a 4-h exchange with 3.86% glucose. Fluids from the overnight exchange were spun to obtain a cellular pellet and the supernatant 100-fold concentrated. RESULTS: No viral genome could be detected in unconcentrated samples and in cellular pellets, while HCV-RNA at low titre was detected in concentrated dialysates from the two patients with active liver disease. CONCLUSIONS: Our findings confirm that HCV may be present in the CAPD effluent of some patients; however, the titre of virus in the effluent was extremely low, at the limit of detection of the PCR assay. Peritoneal fluids originating from patients with HCV associated severe liver disease may be a potential source of infection.

Adult↗
PubMed1997

Continuous ambulatory peritoneal dialysis in patients after intra-abdominal prosthetic vascular graft surgery.

The purpose of this study was to assess the feasibility of continuous ambulatory peritoneal dialysis (CAPD) after intra-abdominal prosthetic vascular graft surgery. We report 8 consecutive patients with end-stage renal disease, who previously underwent intra-abdominal prosthetic aortic graft replacement, treated by CAPD between November 1983 and November 1994. All patients received a peritoneal dialysis catheter without technical problems and were dialyzed for a total of 208 months. Six episodes of peritonitis occurred in 4 patients without clinical evidence of any abdominal aortic graft infection. Three patients developed intermittent claudication and 2 died of myocardial infarct. A similar peritonitis and cardiovascular complication rate was observed in a control group of age- and sex-matched CAPD patients with no aortic prosthesis. We conclude that CAPD is feasible in patients with abdominal aortic prosthesis.

Aged↗
PubMed1996

Nine patients treated for more than 10 years with continuous ambulatory peritoneal dialysis.

We have retrospectively examined the clinical outcomes of the 9 patients who survived for more than 10 years in our continuous ambulatory peritoneal dialysis (CAPD) program. Six were men and 3 women aged 50.8 +/- (SD) 11.5 years. Three had been previously treated by hemodialysis. None of them had diabetes or neoplasms, 1 had liver cirrhosis, 3 had ischemic cardiopathy, 1 had peripheral artery disease, and all were hypertensive. The hospitalization rate ranged from 0 to 4.5 days/patient/year, the peritonitis rate was one episode every 57 months. Six patients had no peritonitis during the first 10 years of treatment. Exit-site episodes were one every 46.7 patient months. Six peritoneal catheters were removed from 4 patients. KT/V and peritoneal permeability, assessed by the peritoneal equilibration test, were within the normal range in the majority of the patients. Five patients died between the 121st and the 149th month, and 4 are still alive. Three of them are working. These results show that CAPD can be effective, peritoneal catheters can survive, and some patients can be free from peritonitis episodes for more than 10 years. After the 10-year on CAPD, the survival is poor, and the morbidity is high.

Adult↗
PubMed1995

Cuff-shaving procedure. A rescue treatment for exit-site infection unresponsive to medical therapy.

We performed 41 cuff-shaving procedures in 38 patients on continuous ambulatory peritoneal dialysis (CAPD) with exit-site infection unresponsive to medical treatment. Cuff shaving was performed on three patients with two catheters each. This procedure was effective in eliminating 50% of S. aureus exit-site infection and all S. epidermidis exit-site infection, but was ineffective in Gram-negative exit-site infection. After cuff-shaving procedure, 20 catheters (49%) were removed; 11 for persistent tunnel infection and nine because of development of secondary peritonitis. The probability of catheter survival at 1 year was 50% and remained stable thereafter. Cuff-shaving procedure may be a valuable mode of therapy for treating patients with S. aureus and/or S. epidermidis exit-site infection unresponsive to medical treatment.

Anti-Bacterial Agents↗
PubMed1994

High prevalence of silent gallstone disease in dialysis patients.

Gallstone disease was detected in 28% of 119 patients on regular dialysis treatment. The disease was silent in 82% of the patients. Stones were radiolucent in 88% of the cases, radioopaque in 8% and mixed in 4%. Among 49 variables considered, increasing age was the only variable that correlated significantly with increasing prevalence of gallstone disease. Since no relationships were found between gallstones and age or modes of dialysis, it is conceivable that some mechanism(s) linked with the preexisting chronic nephropathy might have been involved in the development of cholelithiasis. End-stage renal disease could be another so far unrecognized risk factor for cholelithiasis.

Adult↗
PubMed1994

Incidence, possible causes and social aspects of the symptomatic introduction of disinfectant into the peritoneal cavity in CAPD.

The frequency and characteristics of episodes of accidental symptomatic introduction of Amuchina in CAPD patients has been retrospectively analyzed in patients treated with three different CAPD systems with disinfectant (two reusable Y set and one disposable Y set). The rate of accidental introduction of Amuchina was 1 episode every 8981 exchanges (1/8620 with the log Baxter Y set, 1/11,060 exchanges with the short Baxter Y set and with the Bieffe L3 system). One to 15 fresh dialysis exchanges were required to relief pain due to the introduction of disinfectant. Four patients were hospitalized and one had a long lasting impairment in peritoneal ultrafiltration. There were no significant correlations between the episodes and age, sex or time when the exchange was performed.

Adult↗
PubMed1992

Symptomatic accidental introduction of disinfectant electrolytic chloroxidizer solution into the peritoneal cavity of CAPD patients. Incidence and long-term effects on ultrafiltration.

In recent years the Y-set with disinfectant [Buoncristiani et al. 1983] has been used in several continuous ambulatory peritoneal dialysis (CAPD) centers. This system has considerably improved the short- and long-term results of CAPD [Maiorca et al. 1983, Scalamogna et al. 1990]. Accidental introduction of disinfectant during the exchange is a risk associated with this system, but at the present time we have little data pertaining to incidence complication and its possible effects on peritoneal function. The aim of the present study was to assess the incidence of acute symptomatic accidental introduction of disinfectant in CAPD patients on the Y system and to establish whether this complication is followed by any long-term changes in peritoneal ultrafiltration.

Adult↗
PubMed1992

Effect of simvastatin in CAPD patients with hypercholesterolemia.

The effect of simvastatin on serum total and HDL cholesterol and total triglyceride levels in 20 hypercholesterolemic patients on CAPD treatment was studied. The drug was given at the initial dose of 10 mg/day which was doubled up to 40 mg/day. Two non-compliant patients stopped the drug in the first week of treatment. One patient had vomiting and stopped simvastatin. One patients reduced the dose from 20 to 10 mg/day because of increase in CPK level. The study was completed in 16 patients. Serum cholesterol decreased from 318 +/- 39 to 208 +/- 34 mg/dl (p < 0.001), triglyceride from 317 +/- 129 to 278 +/- 160 mg/dl and HDL cholesterol from 43 +/- 13 to 35 +/- 11 mg/dl. The effective does was 10 mg/day in 4 cases, 20 mg/dl in 7 and 40 mg/dl in 5. In CAPD patients, simvastatin is safe and effective in lowering serum cholesterol. The clinical significance of the decrease in HDL cholesterol and its possible effect on clinical outcome are still unknown.

Anticholesteremic Agents↗
PubMed1991

Exit-site and tunnel infections in continuous ambulatory peritoneal dialysis patients.

One hundred two exit-site infections (ESI) were diagnosed in 63 of 163 (38.6%) patients, with an incidence of one episode every 23.7 patient-months in patients with a history of ESI, whereas in the overall continuous ambulatory peritoneal dialysis (CAPD) population the incidence was one episode every 48.7 patient-months. In diminishing order of frequency, the bacteria isolated were Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli. The probability of remaining free of ESI was 72% at 1 year and 45% at 5 years. The ESI that led to catheter removal were due to S aureus and gram-negative rods. In 13 (48%) of 27 S aureus ESI unresponsive to antibiotics and local care, deroofing and outer cuff shaving completely resolved the ESI. Despite this treatment, the catheters of the remaining 14 patients had to be removed because of peritonitis associated with the tunnel infection. In conclusion, ESI is a major cause of CAPD failure. In our series, shaving the cuff as a rescue treatment was effective for almost 50% of the patients with antibiotic-resistant S aureus ESI.

Bacterial Infections↗
PubMed1991

Gemfibrozil in CAPD patients.

Gemfibrozil was given at a daily oral dose of 600 mg to 28 CAPD patients with serum triglyceride levels higher than 200 mg/dl, after 2 months of low fat low calorie diet. Eleven patients dropped out from the study due to spontaneous withdrawal of the drug or to intercurrent hospitalization. The 17 patients who completed the study showed a significant decrease in serum total (434.6 +/- 207.9 to 237.5 +/- 81.6 mg/dl, p 0.003), VLDL (268.8 +/- 17.8 to 109.2 +/- 66.9 mg/dl, p less than 0.005) and LDL (152.9 +/- 34.6 to 119.2 +/- 30.7 mg/dl, p = 0.004) triglyceride. Serum VLDL cholesterol increased from 108.7 +/- 54.1 to 59.9 +/- 29.0 mg/dl, p = 0.003. Serum HDL cholesterol decreased from 25.4 +/- 4.8 to 35.3 +/- 6.3 mg/dl (p less than 0.001). Apo A1 increased from 117.8 +/- 16.7 to 130.8 +/- 16.7 mg/dl (p less than 0.001) and Apo B increased from 173 +/- 26.7 to 137.8 +/- 21.9 mg/dl (p less than 0.001). No clinical or laboratory side effect was observed in the patients who completed the study. Therefore dropouts were due to the poor patients' compliance rather than to the severity of side effects.

Aged↗
PubMed1990

Aluminium interference in the treatment of haemodialysis patients with recombinant human erythropoietin.

In nine chronic haemodialysis patients a desferrioxamine (DFO) load test (40 mg/kg body-weight) was performed 1 year after the beginning of treatment with recombinant human erythropoietin (rHuEpo). The patients were then divided into two groups. Group A comprised five patients with a greater mean aluminium (204 +/- 28 micrograms/l) than the four patients in group B. Group A was given a mean dose of 25.8 g (range 14-39 g) of DFO over 6 months. Group B (aluminium values 112 +/- 36 micrograms/l) was never treated with DFO. During the period of observation, plasma iron, serum ferritin and transferrin, as well as iron supplementation, did not differ between the groups. After DFO treatment a second DFO load test was performed. The mean predialysis aluminium value was significantly reduced in group A (204 +/- 28 vs 111 +/- 72 micrograms/l; P less than 0.05), while remaining unchanged in group B (112 +/- 36 vs 140 +/- 39 micrograms/l; P = ns). In both groups, the doses of rHuEpo necessary to maintain the same haemoglobin values decreased with time, but reduced significantly only in group A (298 +/- 105 vs 110 +/- 61 mu/kg per week; delta -63%; P less than 0.01). Thus, aluminium interferes with the response to rHuEpo in haemodialysis patients, and the correction of aluminium overload with DFO can allow a considerable sparing of rHuEpo.

Adult↗
PubMed1990

Response of renal transplanted patients to oral calcium load.

In a previous study we demonstrated that cyclosporin-treated renal transplanted patients have a reduced 1,25(OH)2D3 synthesis in comparison with azathioprine-treated transplanted patients. To assess the impact of this defect on intestinal calcium transport we compared the plasma calcium variation and the urinary calcium excretion in 14 cyclosporin-treated and in 12 azathioprine-treated patients, in fasting conditions and 4 hours after an oral calcium load (1 g). In ten cyclosporin patients we also correlated cyclosporin plasma values with plasma 1,25(OH)2D3 values before and after a 25(OH)D3 oral load. After the oral calcium load, plasma and urinary calcium increased significantly in the azathioprine group, while remaining unchanged in the cyclosporin group. A negative correlation between plasma concentrations of cyclosporin and the increment in 1,25(OH)2D3 after 25(OH)D3 oral load was also observed. Thus, our data suggest that cyclosporin impairs 1-alpha hydroxylase activity and alters the response to an oral calcium load.

Adult↗
PubMed1990

Plasma and dialysate immunoglobulin G in continuous ambulatory peritoneal dialysis patients: a multicenter study.

Peritoneal dialysate immunoglobulin (Ig)G concentrations were measured in 120 continuous ambulatory peritoneal dialysis (CAPD) patients evaluated at four dialysis centers in different countries to assess the normal range for dialysate IgG and to investigate the relationships of this protein levels with peritoneal episodes, For 65 of these patients, plasma IgG levels were determined, and IgG clearances were calculated. The mean dialysate concentration of IgG was 6.9 +/- 4.2 mg/dl, and there was no difference between men and women or between patients who had or had not previously undergone hemodialysis. Dialysate IgG concentrations were significantly related to residual renal creatinine clearance and negatively correlated with dialysate volume, plasma albumin and total protein. There were no significant correlations between IgG levels in the dialysate and age, protein losses in the dialysate, time on CAPD or time from the last peritonitis episode. Plasma and dialysate IgG were unrelated to the incidence of peritonitis, statistical analysis being performed with different methods. These results suggest that IgG levels in the dialysate or plasma are not a major factor in the prevention of CAPD peritonitis.

Ascitic Fluid↗