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Biomedical subjects

P M Ghezzi

Publications and source records attributed to P M Ghezzi.

At least 19 recordsLinked to original sources
PubMed2006

New method for phosphate kinetics estimation during hemodialysis and on-line hemodiafiltration with endogenous reinfusion.

AIM: The purpose of this study was to optimize the operative and analytical methodologies to a more exact determination of intradialytic kinetics of the phosphates (P) tested in hemodialysis (HD) and in on-line hemodiafiltration with endogenous reinfusion (HFR - Hemo Filtrate Reinfusion). METHODS: The mass balance measurements of urea and P were carried out in 18 clinically stable HD patients. The effective blood flow (Qb) was measured with a Transonic monitor. The plasma was deproteinized with 10% trichloroacetic acid to prevent breakdown of the proteins and the consequent pseudohyperphosphatemia. Subsequently the supernatant containing the ultrafiltrable phosphates was made to react with a solution of ammonium molybdate for a spectrophotometric reading. RESULTS: The mean urea mass transfer in HD was 16.9 g/session and in HFR 15.4 g/session. The mean P mass transfer in HD was 726 mg/session and in HFR 679 mg/session. Nevertheless, in HFR a significant difference was verified between the clearances of P, between the plasma water side (122.4 +/- 30.8 ml/min) and the dialysate side (105.9 +/- 19.4 ml/min). CONCLUSION: As far as the P mass transfer is concerned, the data obtained is able to be superimposed with that described in the literature during HD, while in HFR it is possible to hypothesize a high efficiency, thanks to an increased output of P in relation to the phenomenon of adsorption which, although is limited, contributes to the transfer of the total mass. Based on this study and re-examining the literature on P kinetics, there is space for methodological improvement both on the operating front with careful determination of the effective Qb, and on the chemical front overcoming the inaccuracy of automatic analyzers in determining the plasma P owing to possible overestimation of phosphatemia and poor sensitivity in measuring the lower levels of P present in the dialysate and/or ultrafiltrate.

Female↗
PubMed2006

Effect of on-line hemodiafiltration with endogenous reinfusion (HFR) on the calcium-phosphorus metabolism: medium-term effects.

AIM: The purpose of the study was to examine the effect of hemodiafiltration with endogenous reinfusion (HFR) compared to hemodialysis (HD) on 28 uremic patients with secondary hyperparathyroidism (2HPT) but positively selected for good and stable control of phosphatemia in order to evaluate the independent effects of dialysis treatments on bone turnover metabolism. METHODS: The study was divided into 3 periods of observation: a) HD for three months; b) HFR for three months; c) HFR for a further 3 months. We analysed the trend of: whole PTH, 1-84 PTH, 7-84 PTH, alkaline phosphatase and its bone isoenzyme, total and ionised calcium, phosphatemia, dose of phosphate binder agents, beta2-microglobulin, CRP. All the variations found were evaluated through mean values +/- SD, t-tests, multivariate analysis. RESULTS: We observed a deceleration in bone turnover characterized by a reduction of the total and bone alkaline phosphatase (IU/mL) from 92.3 +/- 82.8 and 35.8 +/- 49.8 at the end of HD to 63.4 +/- 23.9 and 16.0 +/- 8.7 at the end of HFR, respectively, and 1-84 PTH from 317.5 +/- 264.6 pg/mL at the end of HD to 287.5 +/- 258.9 pg/mL at the end of the 3rd month of HFR. Beta2-microglobulin was reduced from 32.9 +/- 16.1 mg/L at the end of HD to 26.4 +/- 8.1 mg/L already at the end of the first three months of HFR. CRP was reduced from 2.5 +/- 2.6 mg/dL at the beginning of the study to 1.3 +/- 1.7 mg/dL at the end of HFR. There were no differences with regard to: dialytic efficiency, nutritional status, calcemia, phosphatemia (maintained in the K-DOQI range for the entire duration of the study), also thanks to more careful use of phosphate chelating agents. CONCLUSION: We are of the opinion that HFR - essentially thanks to the use of ultrapure endogenous infusate - induces a deceleration in bone turnover due to 2PHT. In addition, phosphate subtraction in HFR is better compared to HD, thanks to the improvement of the anti-inflammatory conditions by removing the cytokines harmful to bone metabolism and excluding a priori the negative effects related to hyperphosphatemia.

Aged↗
PubMed2005

Hemodiafiltration with post-dilution reinfusion of the regenerated ultrafiltrate: a new on-line technique.

AIMS: All convective hemodiafiltration techniques require a replacement fluid, which must have an adequate electrolytic composition and must be sterile and pyrogen-free. Using an integrated adsorption cartridge, the ultrafiltrate can be "regenerated" and used as a replacement fluid (hemo-filtrate reinfusion; HFR). The aim of this study was to evaluate whether the HFR technique as suggested in its original configuration could be improved by inverting the purification sequence (post-dilution HFR; PDHFR) in order to increase the purification efficiency of the whole system. METHODS: We performed standard HFR in 6 uremic patients during 6 months and, subsequently, during further 6 months, PDHFR. The dialytic efficacy of the two techniques and the filter blood loss were evaluated. Moreover, we studied how both techniques affected cytokine levels. RESULTS: We observed a significant increase of urea extraction and of Kt/V values in PDHFR. An equally significant improvement was observed in regard to the extraction of beta2-m and the blood loss. Furthermore, IL6 and TNFalpha decreased significantly after PDHFR treatment. CONCLUSIONS: HFR has proven to be an easy-to-perform hemodiafiltration technique, capable of resolving the typical problem of the other hemodiafiltration technique, the availability and production of a sterile and ultrapure reinfusion solution. The inversion of its configuration has allowed us to improve three aspects that have characterized, in our experience, the treatments performed in the original geometry: the removal of both urea and beta2-m, and the filter. Finally, it's notable that the decrease in cytokines levels achieved with PDHFR might attenuate the uremic micro-inflammatory state.

Adult↗
PubMed2001

Choosing new adsorbents for endogenous ultrapure infusion fluid: performances, safety and flow distribution.

Adsorption may notably contribute to the removal of uremic toxins and to the efficiency of hemodialysis. We examined different uncoated stationary matrixes, charcoals and synthetic resins to establish their adsorptive capacities in relation to low (urea, creatinine) and high molecular weight (beta2-microglobulin, myoglobin) compounds in in vitro conditions (steady state and flow-through) using isotonic solutions or uremic ultrafiltrate. Trace metal, particle release analyses and scanning electron microscopy of different adsorbents were performed. Dynamic flow-distribution studies were made using 99Technetium and analysing the different regions of interest by single head gamma-camera. We show that adsorbents may differ greatly as to their adsorptive capacity depending on flow rate, nature, and total mass of the compounds to be removed from the ultrafiltrate. These studies suggest a methodological approach for screening stationary matrixes for possible application in hemodialysis.

Adsorption↗
PubMed2000

Adsorption in hemodialysis.

The use of sorbents in different blood purification techniques is reviewed. The sorbents used in these therapies are divided into two groups: (1) Adsorption occurs fundamentally because of the hydrophobic properties of the sorbents. In this group, the sorbents used in different dialysis techniques are charcoal and nonionic macroporous resins. (2) Adsorption occurs by chemical affinity, such as ion exchange resins and chemisorbents. Sorbents were initially used in hemoperfusion, which caused many adverse events; later, with the use of coated charcoal, these undesired effects decreased or disappeared, but the adsorptive properties, water control, and acid-base balance still created problems. For these reasons, the use of sorbents in the treatment of chronic renal failure was almost totally discontinued. Little by little, interest in these substances has reappeared, and at present, they have been used in combination with other blood purification techniques such as hemodialysis, hemofiltration, peritoneal dialysis, and finally, hemodiafiltration. Within the various hemodiafiltration techniques, paired filtration dialysis-charcoal is being used to regenerate the ultrafiltrate, which is used as the replacement fluid. Charcoal regenerates the ultrafiltrate and transforms it into a physiological solution with a normal electrolyte composition, calcium, bicarbonate, and glucose, having eliminated the majority of both middle and large molecule uremic toxins. If regeneration is done properly, this replacement fluid is bacteria and endotoxin free. Studies currently are underway on the adsorption of different inflammatory substances in the ultrafiltrate, which could lead to improvement in the biocompatibility of the system.

Adsorption↗
PubMed2000

Hemodiafiltration with online regeneration of the ultrafiltrate.

The concept of regeneration of dialysis fluids and of ultrafiltrate in particular has been recently revisited. Hemodiafiltration with online regeneration of the ultrafiltrate allows the concomitant infusion of sodium, calcium, and bicarbonate. Here, we studied the adsorptive characteristics of an integrated two-step sorbent system relative to different solutes present in the ultrafiltrate: sodium, calcium, phosphate, bicarbonate, uric acid, creatinine, and beta2-microglobulin. In vitro studies were performed in order to differentiate the relative roles for each sorbent (mineral-activated charcoal or hydrophobic resin) in adsorbing a given solute. Ex vivo studies were performed in order to evaluate the presence of cytokines (interleukin-1 beta and tumor necrosis factor-alpha), of cytokine (interleukin-1 beta and tumor necrosis factor-alpha)-inducing activities, and of the cytokine release in response to exogenous bacterial lipopolysaccharide by normal whole blood incubated with ultrafiltrate samples obtained at 15, 120, and 240 minutes after the start of treatment. The results of the present studies show the presence of immunomodulatory substances in the ultrafiltrate and the significant (P < 0.01) increase in the lipopolysaccharide-induced release of both interleukin-1 beta and tumor necrosis factor-alpha. The biological relevance of the ultrafiltrate and the possible relevance of the online, endogenous reinfusion are discussed.

Adsorption↗
PubMed2000

A procedure to teach self-control to children with attention deficit hyperactivity disorder.

This study examined the use of a progressive delay procedure combined with verbal mediation to teach self-control to children with attention deficit disorder. Results showed that when participants were initially given the choice between an immediate smaller reinforcer and a larger delayed reinforcer, all participants chose the smaller reinforcer. When slight delays to obtain a larger reinforcer were instated in conjunction with intervening verbal activity, all participants demonstrated self-control regardless of the content of the verbal activity.

Attention Deficit Disorder with Hyperactivity↗
PubMed2000

Blood flow distribution in sorbent beds: analysis of a new sorbent device for hemoperfusion.

A new polymer-based sorbent cartridge has been recently developed for enhancing middle molecule removal during hemodialysis. The cartridge (Betasorb, Renaltech, New York, USA) has been designed to be placed in series with the dialyzer in the blood circuit. It is therefore important to evaluate the distribution of flow into the blood compartment of the device in order to assess if the surface of the sorbent is utilized to the best. For this purpose, a special imaging technique was utilized. Cartridges were analyzed during a simulated in vitro circulation at 250 and 350 ml/min of blood flow and 25% and 40% hematocrit. Cartridges were placed in vertical position and a cross longitudinal section 1 cm thick was analyzed in sequence by a helical scanner. Dye was injected into the arterial inlet and the progressive distribution was evaluated by sequential densitometrical measures carried out automatically by the machine. The sequential images analyzed by the scanner demonstrated excellent distribution of the flow in the blood compartment with minimal difference between the central and the peripheral regions of the compartment. In particular the following flow velocity pattern could be observed under the different experimental conditions tested. We may conclude that the cartridge design is adequate and no channelling effects could be detected in the blood compartment. The flow distribution is slightly affected by changes in flow rate and hematocrit showing an optimal utilization of the available surface for molecule adsorption.

Adsorption↗
PubMed1998

Removal of cytokines and activated complement components in an experimental model of continuous plasma filtration coupled with sorbent adsorption.

BACKGROUND: Sepsis is associated with enhanced cytokine production. Here, we examined the in vitro removal of plasma cytokines during continuous plasmafiltration coupled with sorbent adsorption. METHODS: Proinflammatory (tumour necrosis factor-alpha, interleukins-1, -8) and anti-inflammatory (interleukin 1 receptor antagonist, soluble tumour necrosis factor receptor type I and II) cytokines in whole blood spiked with Escherichia coli endotoxin were determined during 2-h recirculation in the ultrafiltrate (condition A), plasma filtrate (condition B), before and after different sorbents (of the Amberlite-, Amberchrome- Ambersorb -type and charcoal). We studied the maximal adsorbing capacity, the 1% leakage test for cytokines and C3a des Arg and the adsorption of complement-dependent leukocyte chemiluminescence. Plasma proteins eluted from the resins were examined by sodium dodecyl sulphate polyacrylamide gel electrophoresis and immunoblotting with an anti-human alpha2-macroglobulin. RESULTS: In condition B, we observed a 40- and 121-fold % increase (vs condition A) in the removed mass and clearance of tumour necrosis factor-alpha. For all other cytokines, the removed mass and the clearance increased from 2.3- up to 6-fold. The Amberchrome but not the Amberlite or Ambersorb resins could remove the highest amount of cytokines and could reduce complement-dependent chemiluminescence. Two protein bands of approximately 400,000 D and 200,000 D were eluted only from Amberchrome resins and immunoprecipitated by anti-human alpha2-macroglobulin and anti-human C3c antibodies, respectively. CONCLUSIONS: These studies suggest an efficient removal of cytokines in continuous plasmafiltration with sorbent adsorption. The binding of alpha2-macroglobulin, a carrier of cytokines in plasma, might be a additional mechanism in the removal of cytokines from plasma.

Adsorption↗