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Biomedical subjects

U Buoncristiani

Publications and source records attributed to U Buoncristiani.

At least 19 recordsLinked to original sources
PubMed1995

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.

Adult↗
PubMed1994

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.

Carnitine↗
PubMed1993

Continuous ambulatory peritoneal dialysis connection systems.

The history of the various connection systems proposed and tried during the first 15 years of clinical application of continuous ambulatory peritoneal dialysis (CAPD) is reviewed. In order to understand the reasons for their success or lack of success, the main technical and operating characteristics regarding their efficacy in preventing peritonitis are examined in detail, together with a range of other pros and cons (i.e., reliability, simplicity, ease of use, cost, aesthetical aspects). The result is an updated state-of-the-art review in the field of CAPD connectology, with a look at future trends.

Humans↗
PubMed1993

Better preservation of cognitive faculty in continuous ambulatory peritoneal dialysis.

We employed the so-called event-correlated potential (ECP) P300, a neurophysiological test which explores the circuits of attention and memory in the brain and is altered in subjects with a dismetabolic or degenerative encephalopathy, in order to evaluate the cognitive faculty in two groups of uremic patients [18 on continuous ambulatory peritoneal dialysis (CAPD), 15 on hemodialysis (HD)] comparable with respect to age and time on dialysis. The values of latency (msec) of P300 resulted in CAPD patients 356 +/- 26 in CZ (central zero electrodes) and 357.5 +/- 25 in PZ (parietal zero electrodes), not significantly different from the values in normal controls (341 +/- 14.5 in CZ and 340 +/- 15.6 in PZ) and in HD patients postdialysis (354 +/- 24.4 in CZ and 354 +/- 25.6 in PZ). On the contrary, the predialytic values of HD patients (384 +/- 25.6 CZ and 385 +/- 25.5 in PZ) were significantly different from the postdialytic values and from the values of CAPD patients and controls (p < 0.01). These results support the conclusion that HD is able to restore a normal cognitive faculty only transiently in the postdialytic phase, while CAPD maintains this important function steadily close to the normal range, thus being clearly better than HD.

Adult↗
PubMed1992

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.

Aged↗
PubMed1991

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.

Adult↗
PubMed1989

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.

Animals↗
PubMed1987

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.

Combined Modality Therapy↗
PubMed1986

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.

Adult↗
PubMed1986

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.

Biological Transport↗
PubMed1986

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.

Acidosis↗