bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time Delay Compensation for Closed-Loop Insulin Delivery Systems: A Simulation Study
Authors: Reboldi G.P. , Home P.D. , Calabrese G. , Fabietti P.G. , Brunetti P. , Benedetti M. Massi 
Published: March 2018

Closed loop insulin therapy certainly represents the best possible approach to insulin replacement. However, present limitations preclude wider application of the so-called artificial pancreas. Therefore, a thorough understanding of these limitations is needed to design better systems for future long-term use. The present simulation study was designe: to obtain better information on the impact of the measurement delay of currently available closed-loop devices both during closed-loop insulin delivery and blood glucose clamp studies, and to design and test a time delay compensator based on the method originally described by O.J. Smith. Simulations were performed on a Compaq Deskpro 486/25™ personal computer under MS-DOS™ operating system using Simnon™ rel. 3.00 software. There was a direct relationship between measurement delay and amount of insulin delivered, i.e., the longer the delay the higher the insulin dose needed to control a rise in blood glucose; the closed-loop response in presence of a time delay was qualitatively impaired both during insulin delivery and blood glucose clamp studies; time delay compensation was effective in reducing the insulin dose and improving controller stability during the early phase of clamp studies. However, the robustness of a Smith's predictor-based controller should be carefully evaluated before implementation in closed-loop systems can be considered. 1) 1) Compaq Deskpro is a trademark of Compaq Computer Corporation; MS-DOS is a trademark of Microsoft Corporation; Simnon is a trademark of SSPA Systems.
Principle of Operation, Design Criteria and Fluid Dynamics of a new Bileaflet Heart Valve Prosthesis
Authors: Pietrabissa R. , Marconi W. , Fumero R. 
Published: March 2018

Bileaflet heart valves show the best fluid dynamic behaviour among mechanical valves and, as a consequence, give the best clinical results. A new bileaflet heart valve has been designed whose main characteristics are the kind of leaflet movement, low profile, fluid dynamics and material. Two flat leaflets move freely inside a very low profile housing ring. The movement is described by the rolling without sliding of the leaflet surface around a cylindrical surface on the inner wall of the housing. The opening angle is 85°. Both the leaflets and the housing are machined from a solid piece of titanium and then covered with carbon by ion beam techniques. The design phase and the first fluid dynamic evaluation were done by numerical methods.
Pyrolytic Carbon Coating Enhances Teflon and Dacron Fabric Compatibility with Endothelial cell Growth
Authors: Sbarbati R. , Giannessi D. , Cenni M.C. , Lazzerini G. , Verni F. , De Caterina R. 
Published: March 2018

Compatibility with endothelial cell attachment and growth appears to be an important requisite of vascular prosthetic materials, possibly influencing thrombosis, pseu-dointimal hyperplasia, and accelerated atherosclerosis at the site of blood-material interaction. Since deposition of pyrolytic carbon (PC) on prosthetic surfaces has been associated with enhanced hemocompatibility, in the present study we assessed whether a thin layer (0.5 μm) of PC deposited onto materials such as knitted Teflon® and Dacron® enhanced endothelial cell attachment and growth. Cultured human umbilical vein endothelial cells (HUVEC) were seeded at a density of 4.5 x 104 cells/cm2 on PC-coated and uncoated grafts. In order to quantify endothelial cell attachment on the fabrics, the area of Teflon and Dacron fabrics covered by endothelial cells was estimated on day 2 after seeding using the point counting method in scanning electron micrographs. Subsequently, on days 2 and 4 after seeding, endothelial cell proliferation was measured both as number of endothelial cells and as total proteins of the endothelial cells covering the fabrics. On day 2 endothelial cell growth on PC-coated fabrics was greater (mean ± SE; area 42.3 ± 9.9 mm2, n = 6; cell number 3.9 x 104 ± 3.03 x 103 cells, n = 4; total proteins 14.9 ± 1.2 μg, n = 4) than on uncoated fabrics (area 10.6 ± 4.6 mm2, n = 6; cell number 2.9 x 104 ± 4.3 x 103 cells, n = 4; total proteins 11.3 ± 1.7 μg, n = 4; P < 0.001, < 0.05 and < 0.05, respectively). On day 4 (n = 6) endothelial cells showed marked proliferation and both cell number and total proteins were still significantly higher on PC-coated fabrics (mean ± SE: cell number 1.9 x 106 ± 1.5 x 105 cells, total proteins 754 ± 57 μg) than on the uncoated ones (cell number 1.4 x 106 ± 5.9 x 104 cells; total proteins 567 ± 23 μg, P < 0.05 for both comparisons). LDH activity (a measure of cytotoxicity) and prostacyclin (PGI2) production (a measure of activation of arachidonic acid metabolism, in the culture medium were both less (P < 0.01) in the presence of PC-coating than in its absence. We conclude that a thin PC film on Teflon and Dacron knitted fabrics enhances in vitro endothelial cell attachment and growth and reduces LDH leakage and activation of arachidonic acid metabolism in endothelial cells.
Using Ultrapure Water in Hemodialysis Delays Carpal Tunnel Syndrome
Authors: Baz M. , Durand C. , Ragon A. , Jaber K. , Andrieu D. , Merzouk T. , Purgus R. , Olmer M. , Reynier J.P. , Berland Y. 
Published: March 2018

Since 1977, our patients have undergone chronic HD with ultra-pure dialysate (UPD), defined as having endotoxin levels below 0.008 ng/ml and less than 1 bacteria/ml of dialysate. We evaluated the incidence of carpal tunnel syndrome (CTS) in three groups of patients. Group I (GI), 84 patients, dialysed for 6.1 ± 3.2 years (mean ± SD) with UPD only; Group II (GII), 39 patients, first dialysed for 3.7 ± 2.3 years with non-UPD and afterwards for 8.4 ± 2.1 years with UPD; Group III (G III), 103 patients treated for 6 ± 5.9 years exclusively with non-UPD. All patients were dialysed with cuprophan or cellulose acetate membranes. Results, expressed by Kaplan-Meier actuarial survival curves as the percent of patients without CTS, show that CTS occurred significantly less in GI than in GIII. This may be due to less stimulation of monocytes resulting from the absence of bacteria, endotoxins and pyrogens in the dialysate which would reduce the stimulation of cytokines release, interleukin 1 and 6, and tumor necrosis factor, known to stimulate β2 microglobulin synthesis.
Cardiac Output Requirements and Maximum Dimensions for a Neonate Total Artificial Heart
Authors: Koppert E. , Pantalos G.M. , Tieleman R. , Swier P. , Burns G.L. 
Published: March 2018

Two equally important issues need to be addressed during the early stages of the design of an implantable total artificial heart (TAH): proper anatomical fit and cardiac output capacity. As part of a first-time feasibility study to develop a neonate-size TAH, two studies were conducted to establish useful anatomical and physiological standards. The first (Study A) was conducted to determine the maximum dimensions of a neonate-size TAH. Twelve preserved hearts from full-term neonates with the hypoplastic left heart syndrome were examined. A second study (Study B) was designed to determine the acceptable minimum stroke volume compatible with minimum neonate cardiac output requirements. This study was based on a combination of: a) reported cardiac output studies in healthy term neonates, and term neonates with heart failure, b) body weight range, and c) limiting factors of TAH technology, e.g., valvular regurgitation and leveling off of the maximum cardiac output value at a specific heart rate and filling pressure. The proposed neonatal standards for TAH technology are presented.
Mechanical Support of the Left Ventricle in Ischemia Induced Left Ventricular Failure: An Experimental Study
Authors: Zobel G. , Dacar D. , Kuttnig M. , Rödl S. , Rigler B. 
Published: March 2018

Objective this study compares the hemodynamic effects of intraaortic balloon pumping (IABP), left ventricular assist device (LVAD), and extracorporeal membrane oxygenation (ECMO) in left ventricular failure in pigs. Methods In 29 pigs weighing 12 + 0.7 kg left ventricular failure was induced by ligating the left anterior descending coronary artery. Eight animals served as controls. Eight pigs were treated by IABP, seven by LVAD, and six by ECMO. The study period lasted four hours. Hemodynamic and oxygen transport/ uptake parameters were measured continuously or intermittently. Results Six animals of the ECMO and LVAD groups survived the 4 hour period, but only 3 and 4 animals of the IABP and control groups survived (p<0.05). Cardiac index decreased about 48% and 22% in the control and IABP groups (p<0.05), whereas there was only a slight decrease in the ECMO (9%) and LVAD (14%) groups. Oxygen delivery fell significantly in the control and IABP groups (p<0.05), compared with only a slight change in the LVAD and ECMO groups. Conclusion ECMO is the most effective system for temporary circulatory support in severe ventricular failure. LVAD maintains cardiac output when pulmonary blood flow is provided. IABP is less efficient in supporting the failing heart, especially in the presence of severe ventricular arrhythmias.
Effect of Dialyser Composition and Reuse on Neutrophil Count and Elastase α-1 Proteinase Inhibitor Complex Formation
Authors: Donovan K.L. , Pacholok S. , Phillips A. , Humes J.L. , Coles G.A. , Williams J.D. 
Published: March 2018

To assess the inter-relationship of leucopenia and PMN elastase release we undertook a prospective crossover study of 6 patients dialysed with new and reused cuprophane, cellulose acetate and polysulfone membranes. Serial blood samples were analysed for PMN count, and elastase-α 1-proteinase inhibitor complex (Eα1PI) concentrations. After 15 min dialysis with new membranes median PMN counts fell by 72.2%, 25.3% and 22.1% with cuprophane, cellulose and polysulfone, respectively. With reuse the decreases were reduced to 6.4%, 8% and 13.6%. All membranes produced a gradual increase of Eα1PI. Median Eα1PI accumulation rates (ng ml−1min−1) with new membranes were 175, 169 and 187 for cuprophane, cellulose acetate and polysulfone, respectively. With reuse of cuphro-phane and cellulose acetate these rates fell to 99 and 109 (p<0.05 and p<0.05, respectively), however, with polysulfone it remained unchanged at 180 ng ml−1 min−1. This study highlights differences between two aspects of the neutrophil response to haemodialysis, and demonstrates that extrapolation from individual parameters to conclusions concerning biocompatibility may be inappropriate.
Plasma Exchange Treatment in Rapidly Progressive Glomerulonephritis Associated with Antineutrophil Cytoplasmic Autoantibodies
Authors: Frascà G.M. , Zoumparidis N.G. , Borgnino L.C. , Neri L. , Vangelista A. , Bonomini V. 
Published: March 2018

This study reports on 12 patients with acute renal failure due to biopsy-proven rapidly progressive glomerulonephritis and signs of systemic disease in whom antineutrophil cytoplasmic autoantibodies (ANCA) were detected by indirect immunofluorescence (IIF) on alcohol-fixed neutrophils and assessed in serial determinations by ELISA. The diagnosis was: Wegener's granulomatosis in nine patients who showed a diffuse cytoplasmic pattern at IIF (c-ANCA), and microscopic polyarteritis in three where a perinuclear pattern (pANCA) was seen. All patients underwent a course of plasma exchange - PE - (3-10 sessions per patient) associated with steroids and cyclophosphamide. The ANCA titer dropped steeply during PE in all cases and was followed by disappearance of systemic symptoms and renal function improvement within four weeks. After a follow-up period of 50 ± 31.2 months all patients were alive without signs of disease activity; ten had stable renal function, with serum creatinine 1.8 ± 0.7 mg/dl; two had entered regular dialysis treatment after 44 and 82 months. Our results suggest that the rapid removal of ANCA by means of PE can help control disease activity and reduce the risk of death or end-stage renal disease.
Patterns of Blood Response during Cardiopulmonary Bypass
Authors: Sundaram S. , Irvine L. , Courtney J.M. , Taggart D.P. , Wheatley D.J. , Lowe G.D.O. 
Published: March 2018

Monitoring of cardiopulmonary bypass (CPB) in terms of alterations to the concentrations of selected blood constituents leads to contrasting patterns of response. This has been verified by determining the influence of CPB on the activation of fibrinolysis, complement, leucocytes and the contact phase of coagulation. Fibrinolytic activity was determined by fibrin degradation products (X-FDP's), complement activation by C3a and C5a, leucocyte activation by granulocyte elastase and contact activation by factor XII-like activity (FXIIA). Five patients undergoing elective coronary artery surgery using a bubble oxygenator and pulsatile perfusion were studied. X-FDP's rose gradually during CPB and remained elevated. Similar patterns were observed for elastase and FXIIA. In contrast, C3a rose sharply with peak values at 1½-2h of bypass while C5a did not show significant changes during bypass. The data obtained have enabled the establishment of response patterns for parameters in CPB which will provide information relevant to the clinical application of biomaterials.
Hemostatic Disturbances Induced by Two Hollow-Fiber Hemodialysis Membranes
Authors: Reber G. , Stoermann C. , de Moerloose P. , Ruedin P. , Leski M. 
Published: March 2018

The effects on hemostasis of two high-flux membranes in hollow-fiber configuration, polyamide (PAM) and polyacrylonitrile (AN69), were analyzed in a cross-over study involving ten chronic hemodialyzed patients. Blood samples were obtained at arterial and venous sites of the extracorporeal circuit before dialysis and at 15, 30 and 180 min. Primary hemostasis: PAM induced an early significant drop in platelet counts, but at 180 min there was no longer any difference between membranes. Beta-thromboglobulin release by PAM was significantly higher at all time points. Coagulation: thrombin-antihrombin III complexes (TAT) and fibrinopeptide A increased significantly, the highest values being found with AN69. With both membranes the arteriovenous differences in TAT levels were negative throughout the sessions. Fibrinolysis: no significant differences were observed. In conclusion, both membranes induced hemostatic changes. Although these two hollow-fiber dialyzers look relatively similar, the changes observed were different, polyamide acting mainly on primary hemostasis and polyacrylonitrile on coagulation.
Efficacy and tolerability of recombinant human erythropoietin treatment in pre-dialysis patients: Results of a multicenter study
Authors: Albebtazzi A. , Liberato L. Dl , Daniele F. , Battistel V. , Colombi L. 
Published: March 2018

Chronic renal failure is characterized by a normochromic normocytic anemia, the severity of which generally increases during progression toward uremia. The purpose of the study was to evaluate the efficacy and safety of recombinant human erythropoietin (rHu-EPO) given subcutaneously (s.c.), the dose required to reach and maintain Hb levels within 10 and 11g% and its effects, if any, on the progression of chronic renal failure. Eighty-four pre-dialysis patients (46 F, 38M, age 61.7+13.9 years) with Hb levels between 6 and 9g% and serum creatinine ranging from 3 to 9 mg/dl were treated with s.c. rHu-EPO (2000 U/twice weekly). After 6 weeks, if Hb increase was below 1g%, 1000 U of s.c. rHu-EPO were added at each administration (3000 U twice weekly). Once the Hb target was reached (10–11g%), the rHu-EPO weekly dose was halved and administration reduced to once weekly. The patients showed a significant rise in mean Hb values (p<0.001) after 3 months. Mean Hb values were as follows: 8.00±0.77g% (pretreatment), 9.35±1.0 (3rd month), 10.06±1.04 (6th month), 10.25±0.62g% (12th month). The mean rHu-EPO doses were 4000 U/w (start of the study), 3592+1685 U/w (6th month), 2840±1178 U/w (12th month). Renal function was evaluated by plotting the reciprocal of serum creatinine values vs time with a two period comparison: period A (retrospective-8 mo); period B (prospective-12 mo). The residual renal function was not impaired by rHu-EPO therapy. Meanwhile, no relevant modifications were observed in mean blood pressure values. Low doses of s.c. rHu-EPO were well tolerated, safe and effective; this therapeutic approach should therefore be considered for the improvement of anemia in pre-dialysis patients. A slow and gradual correction of anemia induces an improved sense of well being and a more active of life style. (Int J Artif Organs 1998; 21:12-8)
Monocyte Activation and Humoral Immune Response to Endotoxins in Patients Receiving On-Line Hemodiafiltration Therapy
Authors: Weber C. , Stummvoll H.K. , Passon S. , Falkenhagen D. 
Published: March 2018

With the on-line preparation of substitution fluid, an easy-to-operate and cost-effective alter-native to conventional hemodiafiltration (HDF) has been realized. The continuous filtration of dialysis fluid, furthermore, allows high volumes of exchange. Microbial contamination and subsequently endotoxins, however, may be present in dialysis fluid, and thus the microbiological safety has become a pivotal issue. In this clinical study we evaluated the safety of the Fresenius Medical Care on-line HDF system which is based on a two-stage filtration of dialysis fluid with upstream DIASAFE® and downstream on-line HDF filter. During the three-month study period we failed to detect germs or endotoxins in the substitution fluid. Augmented plasma interleukin-1β (IL-1β) and tumor necrosis factor α (TNFα) concentrations were found neither during the intradialytic period nor when pre-session values at study begin and study end were compared. In addition, changes in the anti-endotoxin core antibody levels and soluble CD14 (sCD14) concentration, or pyrogenic episodes were not observed. On-line HDF with DIASAFE® and on-line HDF filter thus represents a safe treatment modality by effectively depleting dialysis fluid of cytokine-inducing substances.
Evidence of Profiled Hemodialysis Efficacy in the Treatment of Intradialytic Hypotension
Authors: Colì L. , La Manna G. , Dalmastri V. , De Pascalis A. , Pace G. , Santese G. , Stefanio C. , Ursino M. , Zacà F. , Stefoni S. 
Published: March 2018

In the last 10 years the percentage of dialysis patients suffering from clinical intradialytic intolerance has greatly increased. Profiled hemodialysis (PHD) is a new technical approach, alternative to standard hemodialysis (SHD) for the treatment of intradialytic symptomatic hypotension. It is based on intradialytic modulation of the dialysate sodium concentration, using a dialysate sodium concentration profile elaborated by a new mathematical kinetic model. The aim of PHD is to reduce the intradialytic blood volume decrease, thanks to a dialysate sodium profile, which allows a reduction in the plasma osmolarity decrease, thereby boosting intravascular fluid refilling. This work aims at clinically validating the PHD technique, by testing its ability, against SHD, to maintain a more stable intradialytic blood volume; this evaluation was supported by monitoring some hemodynamic parameters. Twelve dialysis patients on SHD treatment were selected because of their intradialytic symptomatic hypotension. Twelve SHD (one per patient) and 12 PHD sessions (one per patient) were performed to achieve the same sodium mass removal and body weight decrease on both PHD and SHD. During these sessions we monitored the blood volume variation % by the critline (a non invasive blood volume monitoring device), the mean blood pressure and heart rate directly and, finally, the stroke volume and cardiac output indirectly by bidimensional doppler-echocardiography. Comparison of the results obtained with the two techniques shows PHD to achieve a significantly more stable blood volume, blood pressure and cardiovascular function than SHD, in particular during the second and the third hour of the dialysis session.
Effects of Dialysis Membranes on the Kinetics of Tumor Necrosis Factor-α Production by Peripheral Mononuclear Cells in Chronic Hemodialysis Patients
Authors: Kushihata S. , Yorioka N. , Oda H. , Ye X.F. , Yamakido M. 
Published: March 2018

To evaluate the biocompatibility of dialysis membranes, blood samples were collected from 10 hemodialysis patients immediately before dialysis and peripheral blood mononuclear cells were isolated. The 3.0 x 105 cells/ml were then passed 30 times through modules made of a polyethylene glycolgrafted cellulose membrane, a polyacrylonitrile membrane, and a polysulfone membrane. Expression of messenger RNA for tumor necrosi factor-α (TNF-α) was determined. Cells were also cultured for 2 h with and without lipopolysaccharide and TNF-α levels in the supernatant were measured. TNF-α messenger RNA expression was significantly higher immediately after passage through the polyacrylonitrile membrane compared with the other membranes. Cells cultured without lipopolysaccharide, produced significantly less TNF-α after passage through the polysulfone membrane, while lipopolysaccharide significantly increased TNF-α production by cells passed through the polyacrylonitrile membrane. These results suggest that biocompatibility differs even among dialysis membranes believed to cause no complement activation.
Quality Improvement Measures Adopted by the Italian National Health Service
Authors: Langiano T. , Martin S.J. 
Published: March 2018

The reform process underway within the Italian National Health System is aimed at making decision makers responsible for appropriate and efficient resource utilisation and at ensuring quality of care, eliminating conflict between fairness, quality and cost control. The risk for the quality of the services provided entailed by resource rationalisation is avoidable and controllable. This article explains how the Italian NHS has managed the reform process assuring quality improvement, and describes the policy and the tools adopted. As well as involving all players and the system as a whole in constant improvement, the Italian NHS's policy in pursuing quality of care is based on the adoption of a wide range of measures: measurement of health care and of clinical outcomes, systematic data collection, team work and protocols. The tools adopted, currently under implementation, to support quality control are: an integrated system of indicators for measuring efficiency and quality of NHS structures (demand and accessibility indicators, resource related indicators, activity indicators and result indicators); compulsory accreditation as a prerequisite for health care providers; a system to monitor and control the effects of the new prospective payment system; clinical guidelines (each related to a specific clinical problem); a menu of services (Carta dei Servizi) released by all NHS accredited service providers with full information and warranties regarding the services provided and their quality.