bluuebunny/crossref_metadata_2025_split huggingface dataset:
CFD Simulation of a Novel Bileaflet Mechanical Heart Valve Prosthesis - An Estimation of the Venturi Passage Formed by the Leaflets
Authors: Yokoyama Y. , Medart D. , Hormes M. , Schmitz C. , Hamilton K. , Kwant P.B. , Takatani S. , Schmitz-Rode T. , Steinseifer U. 
Published: January 2018

The aim of this study was to validate the flow characteristics of the novel Helmholtz-Institute Aachen Bileaflet (HIA-BL) heart valve prosthesis. The curved leaflets of the HIA-BL valve form a Venturi passage between the leaflets at peak systole. By narrowing the cross section the flow accelerates and the static pressure at the central passage decreases according to the Venturi effect. The low-pressure zone between the leaflets is expected to stabilize the leaflets in fully open position at peak systole. To investigate the Venturi passage, the flow fields of two valve geometries were investigated by CFD (Computational Fluid Dynamics): one geometry exhibits curved leaflets resulting in a Venturi passage; the other geometry features straight leaflets. The flow profiles, pressure distribution and resulting torque of both passages were compared and investigated. Although flow profiles downstream of both valves were similar, the flow passages between the leaflets were different for the investigated leaflet geometries. The straight leaflet passage showed a large boundary layer separation zone near the leaflets and the lowest pressure at the leading edge of the leaflet. The Venturi passage showed a reduction of the boundary layer separation zones and the lowest pressure between the leaflets could be found in the narrowest flow cross section of the Venturi passage. Additionally, the resulting torque showed that the Venturi passage produced an opening momentum. The results demonstrate that the Venturi passage stabilizes the leaflets in open position at peak systole.
A Pilot Study of High-Adsorption Hemofiltration in Human Septic Shock
Authors: Haase M. , Silvester W. , Uchino S. , Goldsmith D. , Davenport P. , Tipping P. , Boyce N. , Bellomo R. 
Published: January 2018

Background To compare the hemodynamic and biological effects of high-adsorption continuous veno-venous hemofiltration (CVVH) with standard CVVH in septic shock. Methods: In a randomized cross-over clinical trial twelve patients with septic shock and multiple organ failure were enrolled at a tertiary intensive care unit. Patients were allocated to either 9 hours of high-adsorption hemofiltration (CVVH with 3 hourly filter change using AN69 hemofilters - 3F-CVVH) or 9 hours of standard hemofiltration (CVVH without filter change - 1F-CVVH). Results Changes in hemodynamic variables, dose of noradrenaline required to maintain a mean arterial pressure greater than 75 mmHg and plasma concentrations of cytokines (IL-6, IL-8, IL-10 and IL-18) were measured. A 9-hour period of 3F-CVVH was associated with greater reduction in noradrenaline dose than a similar period of 1F-CVVH (median reduction: 16 vs. 3.5 μg/min, p=0.036; median percentage reduction: 48.1% vs. 17.5%, p=0.028). Unlike 1F-CVVH, 3F-CVVH was associated with a reduction in the plasma concentration of IL-6, IL-10 and IL-18 at 9 hours and a significant decrease 30 minutes after additional filter changes (IL-6: p<0.01, p<0.01; IL-10: p=0.03, p=0.016 and IL-18: p=0.016, p<0.01, respectively). Both, 3F-CVVH and 1F-CVVH were associated with decreased plasma concentrations of IL-8 at 9 hours (p<0.01, p<0.01, respectively). In a confirmatory ex-vivo experiment IL-6 concentrations substantially decreased during 3F-CVVH (at baseline 511pg/mL and at end: 21pg/mL) whereas IL-6 concentrations increased in control blood (at baseline 511pg/mL and at end: 932pg/mL). Conclusions High-adsorption CVVH appears more effective than standard CVVH in decreasing noradrenaline requirements and plasma concentrations of cytokines in septic shock patients.
Sandblasted Titanium Osteointegration in Young, Aged and Ovariectomized Sheep
Authors: Borsari V. , Fini M. , Giavaresi G. , Rimondini L. , Chiesa R. , Chiusoli L. , Giardino R. 
Published: January 2018

To evaluate how aging and estrogen deficiency influence the success rate of Sandblasted Titanium (Ti/SA) implants, the osteointegration of Ti/SA rods was studied in the cortical and trabecular bone of 5 young, 5 aged and 5 ovariectomized (OVX) sheep. The characterization of the host bone by transiliac biopsies of the iliac crest showed a progressive rarefaction of trabecular bone in aged and OVX animals when compared to young ones. A significant reduction, both in cortical and trabecular bone, of the osteointegration rate of Ti/SA rods in the presence of estrogen deficiency compared to young animals was observed, while only a minor reduction was observed in aged animals. These results were confirmed by the pushout test in cortical bone. Bone quality affected the biological response of bone to Ti/SA implants in both trabecular and cortical bone; consequently, strategies to maximize the bone osteogenic properties of osteoporotic patients should be adopted.
Continuous Veno-Venous Hemofiltration in the Treatment of Acute Severe Hyponatremia: A Report of 11 Cases
Authors: Ji D.X. , Gong D.H. , Xu B. , Tao J. , Ren B. , Zhang Y.D. , Liu Y. , Hu W.X. , Wang M.M. , Li L.S. 
Published: January 2018

Objectives To evaluate the treatment effect of continuous veno-venous hemofiltration (CVVH) in patients with acute severe hyponatremia. Methods Eleven patients with severe acute hyponatremia, including 6 males and 5 females, aged 25–61 years (mean age 48.36), were treated with CVVH. Hyponatremia occurred 38–48 hours prior to the initiation of CVVH. Results All patients tolerated CVVH well, with an average treatment duration of 57.19 (45.6–86) hours. During CVVH, the serum sodium concentration increased significantly from 100.9±3.99 mmol/L at initiation of CVVH to 140.3±1.6 mmol/L after 48 hours of treatment (P<0.01). The serum osmolarity increased concurrently, from 216.7±7.4 mOsm/kgH2O to 295.0±4.2 mOsm/kgH2O (P<0.01). The Glasgow scores and APACHE II scores in these patients improved significantly during treatment. Conclusions CVVH is a safe and effective option for the treatment of patients with severe acute hyponatremia due to its slow and continuous nature.
Clinical Effects of Direct Hemoperfusion Using a Polymyxin-B Immobilized Column in Solid Organ Transplanted Patients with Signs of Severe Sepsis and Septic Shock. a Pilot Study
Authors: Ruberto F. , Pugliese F. , D'alio A. , Martelli S. , Bruno K. , Marcellino V. , Summonti D. , Celli P. , Perrella S. , Cappannoli A. , Pietropaoli C. , Tosi A. , Diana B. , Novelli G. , Rossi M. , Corradini S. Ginanni , Ferretti G. , Berloco P. B. , Pietropaoli P. 
Published: January 2018

Background Polymyxin B (PMX-B) is a polycationic antibiotic, known to bind the lipid A portion of endotoxin, a cell wall component found exclusively in gram negative bacteria (GNB). An extracorporeal hemoperfusion device (TORAYMYXIN) has been developed: PMX is covalently bound on the surface of an insoluble carrier material so that the endotoxin can be inactivated in the blood without exerting its toxicity on the brain and kidney The aim of this study was to clarify the efficacy, safety and clinical effects of direct hemoperfusion with an immobilized polymyxin-B fiber column (DHP-PMX) in solid organ transplanted patients with severe sepsis or septic shock. Methods From June 2004 to May 2005, 15 patients (10 men and 5 women), mean age 55 years old (46–65 range), underwent kidney or liver transplantation and developed severe sepsis or septic shock, as defined by the Consensus Conference of American College Physicians/Society of Critical Care Medicine (ACCP/SCCM) criteria. GNB were detected in all the patients receiving conventional treatments including antibiotic therapy, vasopressive or inotropic agents, and ventilation support. The DHP-PMX treatment was performed three times in each patient. Hemodynamic and respiratory parameters, dosage of vasopressor/inotropic drugs were assessed at baseline and after each treatment. Results No adverse events occurred. From baseline to 3rd treatment, mean arterial pressure (MAP) was increased (from 63±5 to 83±4 mmHg), while the dosage of dobutamine (from 7.5±3 to 3±2 mcg/kg/min) and noradrenaline (from 1.3±0.45 to 0.05±0.02 mcg/kg/min) were reduced. The PaO2/FiO2 ratio increased (from 234±38.47 to 290±107.48 mmHg). Conclusion The use of DHP-PMX in association with conventional therapy may be an important aid in patients with sepsis.
Membranes for Dialysis: Can We do without them?
Authors: Hoenich N.A. 
Published: January 2018

Over the past five decades, membranes used for the treatment of chronic kidney disease have continuously evolved. In the course of this evolution, the use of classical non-modified cellulose membranes has declined in favor of cellulose-based membranes in which the basic structure has been modified to improve the biocompatibility profile of the material as well as membranes based on synthetic polymers. In addition to providing improved biocompatibility, manufacturing methods have been innovatively adapted to produce membranes with optimized pore size and pore size distribution. This has led to the more effective removal of molecules involved in the development of complications associated with dialysis treatment. More recently, the approach has been move membranes beyond being just selective barriers with a high performance and to incorporate biological function. Despite these advances, membranes in current clinical use represent a compromise: while efficient in their removal of water soluble compounds, they are non-selective, retain some bioreactivity and differ in their ability to adsorb endotoxins or bacterial fragments that may be present in the dialysis fluid. In this paper, an overview of the membranes used in current clinical practice and their limitations are discussed, together with approaches to solute transport in which no membranes are used.
A Mathematical Model Comparing Solute Kinetics in Low- and High-BMI Hemodialysis Patients
Authors: Cronin-Fine D. , Gotch F. , Levin N. W. , Kotanko P. , Lysaght M. 
Published: January 2018

Background Patients with low Body Mass Index (BMI) on maintenance hemodialysis have a higher mortality risk than patients with elevated BMI. We investigated the use of kinetic modeling to test different hypotheses which have been advanced to explain this relationship. Methods Equations from a three-pool urea-kinetic mathematical model (hepatic mass, extracellular fluid, muscle mass and adipose tissue) were solved to yield predictive profiles of solute and putative toxin concentrations versus time for patients of different body weights. Results For the interdialytic interval, our mathematic model suggests that extracellular solute/toxin concentration increases more rapidly in small patients. Additionally, time average concentration (TAC) is higher for this cohort. A lower value of the muscle mass and adipose tissue mass-transfer coefficient (KMMAT), which determines the rate of solute release into the extracellular fluid, exacerbates this difference. Conclusion These results suggest that higher mortality for smaller dialysis patients may be mediated by higher time average toxin concentration, especially for solutes with a low mass-transfer coefficient value.
Newer Strategies for Anemia Prevention in Hemodialysis
Authors: Handelman G. J. 
Published: January 2018

Anemia prevention for hemodialysis relies primarily on supplemental erythropoietin (EPO) and intravenous iron (IV-iron). The doses of EPO utilized are somewhat higher than normal endogenous rates of EPO production in healthy subjects, and the amount of IV-iron used to boost red blood cell (RBC) production may be greater than the amounts used for erythropoiesis. EPO and IV-iron might be used more efficiently if two fundamental problems were solved in the management of dialysis patients: better vitamin C status, and avoidance of chronic inflammation. The low levels of plasma vitamin C commonly observed in dialysis patients restrict mobilization of stored iron from the reticuloendothelial system (RES), and inflammation has a very similar effect. The impact of low vitamin C levels and concurrent inflammation causes a large amount of iron to be stored, with relatively inefficient utilization for erythropoiesis. Vitamin C intake for dialysis patients is often restricted because of avoidance of vitamin C-rich foods, and because of concerns about oxalosis. Inflammation is a chronic feature of renal disease, which is compounded by infections from use of catheters. Research strategies to improve vitamin C status and to decrease inflammation would lead to better utilization of iron and EPO, and could have parallel benefits for the long-term health of patients on hemodialysis.
Computer and Physical Modeling of Blood Circulation Pump Support for a New Field of Application in Palliative Surgery
Authors: MaƗota Z. , Nawrat Z. , Kostka P. 
Published: January 2018

Objectives One of the most popular palliative procedures performed to increase pulmonary blood flow in children with congenital heart defects is a shunt operation (Blalock-Taussig graft or Glenn procedure), which creates the new blood channel to the pulmonary artery. The main problem with this kind of surgery is poor shunt effectiveness and the lack of possibility to regulate the flow. The aim of this work is to use advanced computer simulation methods to study the effectiveness of a new idea to introduce a small axial blood pump into a Blalock-Taussig (B-T) or Glenn shunt in order to control the blood flow and prevent any increase in the graft stenosis. Methods Physical and computer 3-D simulation based on a finite element mesh (FEM) model was applied. Studies for optimization of the shunt and hybrid shunt with pump were performed for different stages of the disease. Results and Conclusion The graft with the axial pump creates good conditions for the vascular system and pulmonary artery blood flow as well as regulating blood pressure under variable conditions caused by palliative procedures. Its use permits the afterload of the left heart ventricle to be decreased. A palliative procedure is only a temporary solution. When a child grows, while the graft size is fixed, the blood flow through this graft may be not sufficient under changing hemodynamic conditions. The use of an axial pump for regulating the blood flow volume, during palliative procedures, allows to obtain the optimal flow conditions in pulmonary artery and safely wait on the final cardiac surgery correction later. However, the use of a pump mounted inside the graft increased hemodynamic resistance, which caused the flow to decrease up to 70% in the graft when the axial pump was not working.
Comparison of Icodextrin- and Glucose-Based Peritoneal Dialysis Fluids in Their Acute and Chronic Effects on Human Peritoneal Mesothelial Cells
Authors: Bender T. O. , Witowski J. , KsąŻEk K. , Jörres A. 
Published: January 2018

Background Icodextrin-based peritoneal dialysis fluids (PDFs) display several features that may potentially improve their biocompatibility compared to conventional glucose-containing solutions. So far, however, the studies assessing the biocompatibility profile of icodextrin toward human peritoneal mesothelial cells (HPMC) has produced mixed results. The present study was performed to examine the acute and chronic impact of icodextrin on HPMC in vitro in comparison with standard glucose-based PDF. Methods Omentum-derived HPMC were either acutely pre-exposed to or incubated chronically (for up to 10 days) in the presence of icodextrin-PDF. Parallel cultures were treated with conventional PDFs containing either 1.5% or 4.25% glucose. All fluids were tested at neutral pH. HPMC were assessed for viability, proliferation, IL-6 secretion and generation of reactive oxygen species (ROS). Results Incubation in the presence of icodextrin-PDF significantly reduced HPMC proliferation in a manner similar to that of 1.5% glucose-PDF In addition, exposure to icodextrin-PDF impaired viability and IL-6 release from HPMC. This effect occurred both after the short pre-treatment with neat icodextrin-PDF for 1–4 hours and after prolonged incubation (up to 10 days) in media supplemented with icodextrin-PDF (1:1). The dysfunction of icodextrin-treated HPMC was of the magnitude that was between the effects exerted by 1.5%- and 4.25%-glucose PDF. Furthermore, exposure of HPMC to icodextrin-PDF induced a dose-dependent increase in ROS generation which was comparable to that produced by 1.5%-glucose PDF. Conclusion Exposure to icodextrin-PDF may impair viability and function of HPMC. The detrimental effects of icodextrin-PDF are at least as serious as those produced by conventional heat-sterilized low glucose-based PDF.
High Doses of Water Increase the Purifying Capacity of the Kidneys
Authors: Di Paolo N. , Nicolai G.A. , Lombardi M. , Maccari F. , Garosi G. 
Published: January 2018

Background In previous studies we were successful in demonstrating that the administration of water over a short period of time increases the transport capacity in the excretory tract of rabbit ureters by increasing urinary volume in the ureter from 0.3 ml/min to 10 ml/min. This phenomenon may explain the effect of water therapy performed in thermal spas, where the administration of 1–2 liters of mineral water is performed in 30–60 minutes. Objectives The aim of the present study is to investigate if this increased transport capacity can act also in the renal tubular apparatus to modify the excretion of some endogenous substances. Materials and Methods We evaluated daily renal clearances in ten subjects under basal conditions during supplemental administration of 25 ml/kg of mineral water over a 24-hour period and during the administration of the same amount of water over a 30-minute period. Results Subjects who drank a water load of 25 ml/Kg over 30 minutes showed a higher diuresis than that observed in those who drank the same amount over a 24-hour period. Creatinine and urea clearance at 24 hours were significantly higher in subjects who drank the water load over 30 minutes. Serum magnesium levels and folic acid levels were also significantly higher in subjects who drank the water load over 30 minutes. Conclusions Water administration over a short period of time seems to modify the daily excretion of some endogenous metabolites.
Fluid and Volume Monitoring
Authors: Pinsky M.R. , Brophy P. , Padilla J. , Paganini E. , Pannu N. 
Published: January 2018

Background Fluid resuscitation is not only used to prevent acute kidney injury (AKI) but fluid management is also a cornerstone of treatment for patients with established AKI and renal failure. Ultrafiltration removes volume initially from the intravascular compartment inducing a relative degree of hypovolemia. Normal reflex mechanisms attempt to sustain blood pressure constant despite marked changes in blood volume and cardiac output. Thus, compensated shock with a normal blood pressure is a major cause of AKI or exacerbations of AKI during ultrafiltration. Methods We undertook a systematic review of the literature using MEDLINE, Google Scholar and PubMed searches. We determined a list of key questions and convened a 2-day consensus conference to develop summary statements via a series of alternating breakout and plenary sessions. In these sessions, we identified supporting evidence and generated clinical practice recommendations and/or directions for future research. Results We defined three aspects of fluid monitoring: i) normal and pathophysiological cardiovascular mechanisms; ii) measures of volume responsiveness and impending cardiovascular collapse during volume removal, and; iii) measured indices of each using non-invasive and minimally invasive continuous and intermittent monitoring techniques. The evidence documents that AKI can occur in the setting of normotensive hypovolemia and that under-resuscitation represents a major cause of both AKI and mortality ion critically ill patients. Traditional measures of intravascular volume and ventricular filling do not predict volume responsiveness whereas dynamic functional hemodynamic markers, such as pulse pressure or stroke volume variation during positive pressure breathing or mean flow changes with passive leg raising are highly predictive of volume responsiveness. Numerous commercially-available devices exist that can acquire these signals. Conclusions Prospective clinical trials using functional hemodynamic markers in the diagnosis and management of AKI and volume status during ultrafiltration need to be performed. More traditional measure of preload be abandoned as marked of volume responsiveness though still useful to assess overall volume status.
Embryonic Stem Cell Sphere: A Controlled Method for Production of Mouse Embryonic Stem Cell Aggregates for Differentiation
Authors: Rohani L. , Karbalaie K. , Vahdati A. , Hatami M. , Nasr-Esfahani M.H. , Baharvand H. 
Published: January 2018

Objectives Embryonic stem cells (ESCs) are of significant interest as a renewable source of nonproliferating cells. Differentiation of ESCs is initiated by the formation of embryoid bodies (EBs). Standard methods of EB formation are limited in their production capacity, in any variations in EB size and formation of EBs through frequent passages. Here we have reported the utility of a microencapsulation technique for overcoming these limitations by mass production of mouse ESCs in alginate beads called ESC spheres. Methods The mouse ESCs were encapsulated in 1.2% alginate solution and cocultured on a feeder layer. The cells were evaluated by flow cytometry, in vitro differentiation, immunofluorescence, and reverse transcriptase polymerase chain reaction (RT-PCR). Results Analysis of encapsulated ESC spheres by flow cytometry showed similar percentages of Oct-4 and stage-specific embryonic antigen-1 (SSEA-1) expression in comparison with routine culture of ESCs. Moreover, the ESC spheres maintained a pluripotency potential which was comparable with ESCs cultured on feeder cells directly, as demonstrated by immunofluorescence and RT-PCR. Conclusions The results demonstrated that alginate encapsulation as a simple bioreactor, provides a scalable system for mass undifferentiated ESC sphere production with similar sizes and without the need for frequent passages for differentiation and clinical and pharmaceutical applications.
Hemodialysis Dialyzers Contribute to Contamination of Air Microemboli that Bypass the Alarm System in the Air Trap
Authors: Stegmayr C. , Jonsson P. , Forsberg U. , Stegmayr B. 
Published: January 2018

Background Previous studies have shown that micrometer-sized air bubbles are introduced into the patient during hemodialysis. The aim of this study was to investigate, in vitro, the influence of dialysis filters on the generation of air bubbles. Methods Three different kind of dialyzers were tested: one high-flux FX80 dry filter (Fresenius Medical Care AG&Co. KGaA, Bad Homburg, Germany), one low-flux F8HPS dry filter (Fresenius Medical Care AG&Co. KGaA, Bad Homburg, Germany) and a wet-stored APS-18u filter (Asahi Kasei Medical, Tokyo, Japan). The F8HPS was tested with pump flow ranging between 100 to 400 ml/min. The three filters were compared using a constant pump flow of 300 ml/min. Measurements were performed using an ultrasound Doppler instrument. Results In 90% of the series, bubbles were measured after the outlet line of the air trap without triggering an alarm. There were significantly more bubbles downstream than upstream of the filters F8HPS and FX80, while there was a significant reduction using the APS-18u. There was no reduction in the number of bubbles after passage through the air trap versus before the air trap (after the dialyzer). Increased priming volume reduced the extent of bubbles in the system. Conclusions Data indicate that the air trap does not prevent air microemboli from entering the venous outlet part of the dialysis tubing (entry to the patient). More extended priming of the dialysis circuit may reduce the extent of microemboli that originate from dialysis filters. A wet filter may be favorable instead of dry-steam sterilized filters.