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Biomedical subjects

C Tetta

Publications and source records attributed to C Tetta.

At least 181 records · Page 10Linked to original sources
PubMed1979

Detection of immune complexes on the surface of polymorphonuclear neutrophils.

A simple immunohistological test has been developed to detect and to quantitate the presence of immune complexes (IC) on the surface of human polymorphonuclear neutrophils (PMN). The interaction between IC and PMN has been evaluated in several human IC diseases. High amounts of immunoglobulins (Ig) and C3 were detected on the PMN surface from these patients. The deposits of Ig and C3 were inversely related to the percentage of membrane-free receptors for Fc and C3.

Acid Phosphatase↗
PubMedDate not supplied

Blood tubing and cytokine production: effect of sterilization.

Blood tubings commonly represent an integral component of hemodialysis circuits. Different factors may influence their biocompatibility, such as the type of material, the sterilization mode and the geometry. In vivo the final biocompatibility may be further complicated by the individual host response, the flow parameters, and the impact of mechanical trauma on blood's cellular components (i.e. erythrocytes). In this in vitro study we evaluated some commercially available blood tubings sterilized by different methods as to their interaction with normal leukocyte population and tested the response of these cells in terms of cytokines (IL-1beta, IL-1Ra, TNF-alpha). As a positive control, leukocytes were incubated with 0.5 ng/mL of bacterial lipopolysaccharide (LPS) or with Cuprophan of comparable surface. The results showed that cytokine production was markedly reduced, particularly in the case of gamma-ray-sterilized tubings. Of interest, it was not always related to the adherence. However in some cases, particularly of gamma-ray sterilization, adherence was none, despite the cytokine production.

Apoptosis↗
PubMedDate not supplied

C reactive protein in patients with chronic renal diseases.

Base-line serum levels of plasma C-reactive protein (CRP) are predictive of future myocardial infarction and sudden cardiac death in apparently healthy subjects, suggesting the hypothesis that chronic inflammation might be important in the pathogenesis of atherothrombosis. CRP production is mediated by several inflammatory mediators: interleukin 6 (IL-6) is currently felt to be the major cytokine influencing the acute phase response. CRP and other acute phase proteins are elevated in dialysis patients and cardiovascular diseases represent the single largest cause of mortality in chronic renal failure patients. Little information is available, however regarding CRP and IL-6 plasma levels in pre-dialysis renal failure. Plasma CRP was determined by a modification of the laser nephelometry technique; IL-6 by immunoassay (RD System); and fibrinogen, serum albumin, cholesterol, triglycerides, hematocrit, white blood cell count, erythrocytic sedimentation rate (ESR) and urinary protein levels by standard laboratory techniques. Results were obtained in 102 chronic pre-dialysis patients whose mean age was 53+/-5.8 years with a mean creatinine clearance (C(Cr)) of 52+/-37 mL/min). CRP was greater than 5 mg/L in 25% of the global population. CRP and IL-6 were 4.0+/-4.6 mg/L and 5.8+/-5.6 pg/mL, respectively and were not significantly correlated (r=0.11, p=n.s.). CRP and IL-6 were however related with renal function (CRP versus C(Cr) r=-0.40 p <0.001; IL- 6 versus C(Cr) r=-0.45; p <0.001). When patients were divided in two groups according to renal function, CRP resulted 7.4+/-6.3 mg/L in the group of patients with a C(Cr) lower than 20 mL/min (n=32) and 2.76+/-4.35 in the group of patients with a C(Cr) higher than 20 mL/min (n = 70) (p <0.0001). CRP and IL-6 were positively related with ESR (r=0.32 and 0.46 respectively). Serum albumin levels were not significantly different in the two groups of patients (3.2+/-0.4 versus 3.0+/-0.5 g/dL). CRP and serum albumin were not significantly related (r=0.17). CRP and IL-6 correlated positively with ESR (r=0.32 and 0.46 respectively). In pre-dialysis patients we have demonstrated an increase in both CRP and IL-6 that occurs as renal function decreases. These data provided evidence of the activation - even in the predialysis phase of renal failure - of mechanisms known to contribute to the enhanced cardiovascular morbidity and mortality of the uremic syndrome.

C-Reactive Protein↗
PubMedDate not supplied

Oxidation of albumin is enhanced in the presence of uremic toxins.

Albumin has been considered a "sacrificial plasma antioxidant" due to the high reactivity of the protein sulfhydryl groups with oxidants such as hydrogen peroxide (H2O2) and hypochlorous acid (HOCl). Based on its large quantity and high turnover. It is considered as one of the most important plasma antioxidants for protecting key cellular and regulatory proteins. Since hemodialysis patients have lower overall levels of albumin and possible protein modifications due to uremic toxins, we investigated whether modifications by various uremic toxins would affect the susceptibility of albumin to an oxidative challenge. We incubated bovine serum albumin in the presence of carboxymethyllysine (CML) (10 micromol/L(-1) mmol/L), methyl glyoxal (50 micromol/L(-5) mmol/L), p-cresol (100 micromol/L-10 mmol/L) or hippuric acid (200 micromol/L-20 mmol/L) for 16 hours at 37 degrees C and then subsequently added 0.5 mmol/L(-1) mmol of H2O2/HOCl. We measured the extent of protein modification by the loss of protein sulfhydryl groups, dityrosine formation and the formation of advanced oxidation protein products (AOPP). Incubation of albumin with the uremic toxins caused a loss of protein sulfhydryl groups and an increase in dityrosines and AOPP. The presence of uremic toxins had no effect on the loss of protein sulfhydryl groups after addition of H2O2/HOCl; however, low levels of CML, p-cresol and methyl glyoxal inhibited the formation of AOPP and dityrosines. We suggest that uremic toxins may possibly play a role in mediating free radical initiated protein damage.

Albumins↗
PubMedDate not supplied

Plasma C-reactive protein is linked to backfiltration associated interleukin-6 production.

Bacterial contamination of dialysate may enhance cytokine production in hemodialysis. The authors tested the hypothesis that C-reactive protein and interleukin-6 (IL-6) may be linked in a large group of patients exposed to backfiltration of dialysate over a long period of observation. Plasmas stored in a recently published multicenter study were reevaluated. Plasma C-reactive protein and IL-6 concentrations in patients with chronic uremia undergoing hemodiafiltration, which is known to be associated with backfiltration (Group II, 12 patients), were compared with those found in patients treated with a modified hemodiafiltration modality without backfiltration (Group I, 16 patients), and in patients shifted from one modality to the other (Group III, 27 patients), and in 10 patients on hemodialysis (Group IV) in a 1 year multicenter study. Plasma C-reactive and IL-6 both increased significantly (p < 0.002), but slowly (after 8 months) in Group II compared with I, and during the 4 month period in hemodiafiltration with backfiltration in Group III. Backfiltration of dialysate with a moderate to low degree of contamination may enhance synthesis of cytokine and C-reactive protein in the long term. Thus, the relevance for dialytic strategies aiming at improving dialysate quality or at reducing backfiltration is highlighted.

C-Reactive Protein↗
PubMedDate not supplied

Assessment of efficiency using on-line urea kinetic modeling in hemodiafiltration.

Urea kinetics has recently been re-evaluated using an on-line urea monitoring system applied to hemodiafiltration. This system allows evaluation of different components possibly responsible for the gap between prescribed and delivered dose of dialysis, such as access and cardiopulmonary recirculation, and altered dialysis parameters, such as blood flow and dialysate flow rates. Furthermore, the system allows prediction of postdialysis rebound urea concentrations. The aim of the present study was to apply the on-line urea monitoring system to assess the dialytic efficiency of double chamber hemodiafiltration in different conditions of blood-dialysate flow rates, reinfusion volumes, and dialyzer configurations (high + low flux membranes or high + high flux membranes) in 10 patients (age, 60 +/- 9 years; dry weight, 65 +/- 5 kg). There was a significantly lower Kt/V (K, dialyzer clearance; t, dialysis time; V, urea distribution volume) at equilibrium with the high + high vs high + low flux configuration, possibly because of a higher tendency toward urea compartmentalization. This difference was evident when reinfusion was performed post dilution. These studies support the concept that small molecular weight uremic toxins may be more efficiently removed using low flux membranes in a modified form of hemodiafiltration.

Blood Flow Velocity↗
PubMedDate not supplied

Retention of limulus amoebocyte lysate reactive bacterial products by polysulfone dialyzers is affected by the type of disinfectant.

To reduce the level of contamination by bacterial products, ultrafiltration systems have been introduced and validated for their capacity to block the passage of bacterial components reactive to the limulus amoebocyte lysate (LAL) test. In this study, the absorptive capacity of polysulfone membranes undergoing disinfection cycles with free chlorine and peracetic acid were evaluated at various concentrations and contact times. The results of this study implicate a relevant physicochemical derangement of the polysulfone membranes treated with sodium hypochlorite but not with peracetic acid, diluted peracetic acid (Dialox) or Amuchina. The implications for the practical use of ultrafilters are discussed.

Disinfectants↗
PubMedDate not supplied

Effect of sodium pool changes on blood pressure in patients undergoing PFD: design of a prospective randomized multicenter trial.

Blood pressure control is important during dialysis and the interdialytic period because of the frequency and potential seriousness of hypotension and hypertension. Water and sodium removal play an important role in the genesis of intradialytic cardiovascular instability or hypertension. Changing dialysate sodium concentrations without the aid of a kinetic model can sometimes give good results but is only an empirical approach. Therefore, this clinical trial was designed to prospectively investigate the advantages of changes in the sodium pool on the blood pressure profile of patients undergoing paired filtration dialysis (PFD). The hypothesis to be tested is whether using a dialysate conductivity which, according to the conductivity kinetic model, ensures that the conductivity of the ultrafiltrate at the end of each dialysis session is 0.3 mS/cm more (B) or less (C) than the mean during the run-in period, improves blood pressure control either in patients prone to intradialytic hypotension or patients who are hypertensive or normotensive with antihypertensive treatment. Patients will be randomly allocated to one of two treatment sequences (where treatment A is standard PFD): AABB or ABAA for patients with intradialytic hypotension; AACC or ACAA for hypertensive patients. During the experimental phase arterial blood pressure will be measured and symptoms reported by the patients will be recorded.

Blood Pressure↗
PubMedDate not supplied

Continuous urea monitoring in hemodialysis: a model approach to forecast dialytic performance. Results of a multicenter study.

BACKGROUND: A urea biosensor, inserted into the ultrafiltrate collection-line of paired filtration dialysis (PFD), not only allows on-line dialysis quantification, but also forecasts final (Cend) and 30 min equilibrated urea concentration (Ceq), the most reliable value for calculating dialysis efficiency. The urea biosensor processes plasma ultrafiltrate continuously, delivering a large amount of data to the computer, which estimates the parameters by a mathematical model, thus predicting the whole urea profile with rebound. METHODS: A multicenter randomized trial on 41 patients was conducted to ascertain the ability of a two-pool variable-volume urea model to forecast Cend and Ceq at 60 and 90 min after the start of dialysis. Two alternative dialytic treatments, A or B, were chosen, the latter being more efficient. Each treatment included six serial PFD. The accuracy of forecasting was evaluated through four indices based on forecast errors, calculated as the difference between observed and forecasted urea values: mean percent error (MPE) (%), mean absolute deviation (MAD) (mg/dl), mean absolute percent error (MAPE) (%) and root mean squared error (RMSE) (mg/dl). RESULTS: Forecasted urea concentrations were lower than those measured by the biosensor. MPE for Cend was negligible in A (+1.2%) and much higher in B (+7.2%); both values improved at 90 min, +1.0% and +5.8%, respectively. MAD for Cend was similar in both treatments and improved slightly at 90 min, ranging from 4.9 to 5.9 mg/dl. MPE for Ceq was +4% in A and and more than doubled in B (+11.5%); both values improved at 90 min, +3.7% and +9.7%, respectively. MAD for Ceq was 7.5 mg/dl in A and 8.5 mg/dl in B; both improved at 90 min, 6.7 and 7.4 m g/dl, respectively. The other indices, MAPE and RMSE, showed similar results. Comparison between the errors of the two treatments with analysis of variance (ANOVA) for repeated measures gave no significant results. CONCLUSIONS: Our model forecasts of urea concentrations were overall lower than the measured ones: the bias was negligible for A-Cend, greater for the A-Ceq and when the more efficient treatment B was used. The 60 min predictions improved at 90 min. The comparison between the prediction errors in the two treatments were not statistically significant. The recirculation measurement would probably reduce the bias if it were properly incorporated into the model.

Filtration↗
PubMedDate not supplied

Alterations of the cytokine network in hemodialysis.

This study focuses on the mechanisms responsible for monocyte activation and enhanced cytokine production in hemodialysis. Particular emphasis is given to recent recognition of a link between cytokine production and chronic inflammation following long-term complications in today's hemodialysis population, namely cardiovascular disease and malnutrition.

Chronic Disease↗
PubMedDate not supplied

[Treatment of septic shock with the use of CPFA (associated plasma filtration and adsorption): impact on hemodynamics monitored with PiCCO ].

BACKGROUND: Septic shock represents an emerging pathology and sepsis and its complications are the main cause of death in medical and surgical intensive care units. Single-target therapeutic trials failed to demonstrate any benefit, suggesting that the unselective removal of different mediators may be a more appropriate approach. METHODS: We evaluated a new technique (CPFA) combining a plasma-adsorption (with plasma filter and sorbent cartridge) with a traditional 'slow' extracorporeal treatment on 10 patients, 7 men and 3 women (mean age 53.8+/-16.3), all on mechanical ventilation, with septic shock and multiorgan failure. To identify easily comparable clinical data, the hemodynamic parameters of the patients were monitored with a recently developed, minimally invasive technology, Pulsion PiCCO . RESULTS: We obtained significant improvement of pre- versus post-treatment mean arterial pressure 77.2+/-12.5 vs. 83.3+/-14.1 mmHg (p<0.0001), cardiac index 4.03+/-0.89 vs. 3.46+/-0.82 L/m2/min (p<0.0001), indexed systemic vascular resistances 1388+/-496 vs. 1753+/-516 dynes x sec/cm5 (p<0.0001), PaO2/FiO2 ratio 204+/-87 vs. 232+/-81 (p<0.0001), and norepinephrine requirements 0.13+/-0.07 vs. 0 y/kg/min after a mean of 5.3+/-2.7 consecutive treatments. The survival at day 28 was 90%. Seven patients were discharged from the intensive care unit after a mean of 37.8+/-24 days (range 10-93). CONCLUSIONS: Our data suggest a promising role for CPFA in improving hemodynamics and correcting vasoparalysis in septic shock. Moreover, the noninvasive monitoring of hemodynamic parameters with PiCCO could become a useful tool for estimating the effect of treatment and gaining easily comparable data in different patients.

Adsorption↗
PubMedDate not supplied

[Role of tumor necrosis factor in hemodiafiltration].

The Authors review the mechanisms involved in the production of cytokines during substitutive extracorporeal treatment with particular reference to microbial contamination and possibility of backfiltration of bacterial constituents more likely to occur with high permeability membranes. Recent and on-going studies from our laboratory support the contention that patients treated with high permeability membranes may be chronically stimulated. Use of "ultrapure" solution indeed brings about a marked reduction in predialytic plasma levels of tumor necrosis factor (TNF) in regard to what observed when standard solutions are adopted.

Acrylic Resins↗