bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of the Redy® Sorbent System to Hemodialysis and Peritoneal Dialysis
Authors: Blumenkrantz Michael J. , Gordon Arthur , Roberts Martin , Lewin Andrew J. , Peeker Edwin A. , Moran John K. , Coburn Jack W. , Maxwell Morton H.
Published: July 2010

The application of sorbent technology to the treatment of uremia has been limited by the inability to adsorb urea adequately. Conversion of urea to ammonium carbonate and adsorption by zirconium phosphate provides a practical means of removing urea. This combination, together with hydrated zirconium oxide and carbon, removes uremic waste products from dialysate. Over 1500 patients are undergoing maintenance hemodialysis with this system. The dialysate composition can be modified for the treatment of patients with acute renal failure. This sorbent system is now being used for the regeneration of peritoneal dialysate. Twenty patients have undergone a total of 90 dialyses, each of 4 to 24 hours duration. One home patient has been solely on this system for two months. The application of sorbent technology to peritoneal dialysis may be the most promising approach to a wearable dialysis system.
The Use of Lyophilized Vein Grafts in Vascular Access for Chronic Hemodialysis
Authors: Merrill Richard H. , McLeod Charles G. , Jarstfer Bruce S.
Published: July 2010

The feasibility of utilizing lyophilized veins for creation of A‐V fistulas was examined in two studies. In Study I, the longevity of lyophilized vein fistulas was found to be comparable to that of fresh veins in the experimental animal. Study II showed that lyophilized cadaveric veins performed at least as well as bovine grafts when used for vascular access in chronic hernodialysis patients. The advantages of lyophilized veins for creation of A‐V fistulas in dialysis patients are described.
A New Method of Urea Removal Using Urease and Expanded Polytetrafluoroethylene Membrane
Authors: Ota Kazuo , Era Kazuo , Suwa Shuji , Kaneko Iwakazu , Aida Kazuo , Agishi Tetsuzo
Published: July 2010

A new method for urea removal using a gas membrane is introduced along with some preliminary results. The membrane used was expanded polytetrafluoroethylene (E‐PTFE) which is highly permeable to gaseous substances, while at the same time it is highly resistant to water permeation.

In in vitro experiments using 10 mmol/L ammonia solution it was revealed that the single‐pass reduction rate was approximately 95% at 30°C at a flow rate of 200 ml/min.

In animal experiments using four dogs, the extraction rate of urea was 40.4 ± 4.4% after four hours of dialysis using 5 L dialysate. However, elevation of blood ammonia was observed in all dogs tested.

Removal of ammonia by means of a gas membrane is considered to be feasible and has the possibility of being used for maintenance hemodialysis in combination with urease and charcoal.
In Vitro Comparison of Observed and Calculated Mitral Valve Areas
Authors: Walker David K. , Scotten Lawrence N. , Brownlee Richard T.
Published: July 2010

Mitral valve bioprostheses (29 mm in diameter) were tested to determine how well areas observed in vitro correlated with the areas calculated using clinical formulas. A hydromechanical left heart and a mock circulation provided close simulation of physiological geometxies, pressures and flows. The test facility was instrumented to accurately measure and record unsteady pressure and flow. Transparent materials allowed detailed cinematography of valve action from the ventricular aspect. The photographic records were digitized and computer processed to determine the temporal variation of valve area at three different heart rates. The calculated valve areas were obtained by substituting pressure and flow measurements into the formulas of Aaslid and Gorlin and compared with the maximum observed areas measured at the exit plane of the valves. The Aaslid formula uses the instantaneous transvalvular pressure difference measured at peak flow. The Gorlin formula uses mean transvalvular pressure difference and stroke volume during ventricular diastole. The observed and calculated areas correlated well for the three Hancock (Hancock Laboratories, Inc., Anaheim, California, U.S.A.) and two Carpentier‐Edwards (Edwards Laboratories, Santa Ana, California, U.S.A.) valves tested, with the Aaslid formula showing a closer correlation than the Gorlin formula. The formulas, however, significantly underestimated the area calculated for the two Ionescu‐Shiley (Shiley, Inc., Irvine, California, U.S.A.) valves tested. The reasons for this discrepancy are discussed.
A New Technique to Increase Coronary Flow Preliminary Report
Authors: Moulopoulos Spyridon , Stamatelopoulos Stamatios , Boufas Demetrios , Yannopoulos Christos , Marousis George , Kouvaras George
Published: July 2010

This study was planned to investigate whether part of the energy produced by cardiac contraction to propel blood toward the systemic circulation can be used to increase the coronary flow in systole. Ten devices (I—X) designed to divert laterally part of a flow column (without substantially increasing resistance to flow) were tested in a mock circulation and in nine anesthetized dogs. An increase of 11.69 ± 1.97% (mean k SEM, P<0.005) in “coronary flow” and of 8.980.56% (mean±çM, P < 0.001) in coronary sinus flow were obtained with device I mounted on a stylet and placed above the “aortic valve” in the mock circulation and the dogs, respectively, without increasing the flow resistance. The results indicate the possibility of diverting part of the aortic flow toward the coronary arteries without increasing mean aortic pressure.
Collagen Film for Burn Wound Dressings Reconstituted from Animal Intestines
Authors: Shettigar U. R. , Jagannathan R. , Natarajan R.
Published: July 2010

Collagen was isolated and purified from sheep intestines and cast into a film. The collagen film was cross‐linked with ultraviolet light and reinforced by imbedding a nylon mesh. The collagen membrane was evaluated as a wound dressing for second‐ and third‐degree burns in rats. Histopathological studies of the burns with and without the collagen dressings were made. The study showed the burn wounds dressed with collagen membrane exhibited rapid epithelialization with little inflammatory change and dense fibrous tissue ingrowth in the subdermal layers.
Total Implantation of a Remotely Controlled Insulin Minipump in a Human Insulin‐Dependent Diabetic
Authors: Selam J. L. , Slingeneyer A. , Chaptal P. A. , Franetzki M. , Prestele K. , Mirouze J.
Published: July 2010

This study reports our first total implantation of an insulin minipump in a severely unstable 23‐year‐old female insulin‐dependent diabetic.

The implantable unit includes a stepping motor, a per‐cutaneously refillable insulin reservoir (10 ml, U 100 special insulin), a battery with a life span of one year, and a method for prevention of overdosage. Variable continuous basal and superimposed 1‐hour high rates are programmed and checked via an external remote controller. The pump was inserted in the lateral muscles of the abdomen and the insulin delivery catheter terminated in the peritoneal cavity.

Excellent glycemic control was reached rapidly and has continued seven months after implantation (mean blood glucose is 123 ± 62 mg/dl; glycosylated hemoglobin is 7.0 ± 1.2%), with the unit providing the only source of insulin. The only negative aspects were a chronic lymphorrhea in the first two months, and a need for frequent and laborious insulin refills (every 20 days). Only slight local discomfort was experienced.

Thus, although further miniaturization and autonomy are expected, these preliminary results show that with careful instruction and followup, implanted pumps could represent a reliable and safe alternative to conventional insulin therapy for selected diabetics.
Physical and Aerodynamic Features of the Bordeaux Voice Prosthesis
Authors: Jebria Abdellaziz Ben , Henry Christophe , Petit Jacques , Gioux Maxime , Devars François , Traissac Louis
Published: July 2010

Abstract: Performance of a voice prosthesis, used to restore speech in patients following total laryngectomy, was evaluated by measuring in vitro, as well as in vivo, airflow resistances. The pressure‐flow characteristics of the device were analyzed using the standard pressure‐flow diagram (to calculate airway resistance) and a Moody plot (to determine the different flow patterns). The flow rate and the pressure drop were measured with a Fleisch pneumotachograph and a variable reluctance transducer, respectively. Total device resistances were found in the range of 34–50 cm H2O/L/s when the flowrates ranged from 0.05 to 0.35 L/s. Comparison of these resistances with those of other commercially available devices showed that our voice prosthesis had the lowest resistance.
Effect of Left Ventricular Assist Device (LVAD) on Myocardial pH Change after Regional Coronary Occlusion
Authors: Matsumoto Takeo , Mitamura Yoshinori , Mikami Tomohisa
Published: July 2010

Abstract: To evaluate the effect of an assist pump on the metabolic viability of the ischemic myocardium, myocardial pH was continuously monitored using an ion‐sensitive field‐effect transistor (ISFET) pH sensor in 14 dogs after coronary occlusion. In seven dogs (control group), coronary occlusion (10–20 min) and successive reperfusion (30–60 min) were performed several times. In seven dogs [left ventricular assist device (LVAD) group], the LVAD was implanted between the left atrium and the aorta. Occlusion and reperfusion were performed first with the pump on and then with the pump off. In both groups, myocardial pH fell after occlusion, and increased after reperfusion. In the control group, the fall rate of pH in the later coronary occlusion decreased to 66 ± 7% (mean ± SEM) of that in the previous occlusion. Contrarily, in the LVAD group, the fall rate under LVAD‐off increased to 174 ± 32% of that under the preceding LVAD‐on. This indicates that progressive cellular damage occurred in the control group, while the myocardium was preserved by the assist pump in the LVAD group. LVAD is effective for preserving the metabolic viability of the ischemic myocardium.
Complications of Plasma Exchange in the Treatment of Polyarteritis Nodosa and Churg‐Strauss Angiitis and the Contribution of Adjuvant Immunosuppressive Therapy: A Randomized Trial in 72 Patients
Authors: Lhote F. , Guillevin L. , Leon A. , Bussel A. , Lok C. , Sobel A. , Simon P.
Published: July 2010

Abstract: We recorded side effects and other complications of 813 plasma exchanges used in early treatment of polyarteritis nodosa and Churg‐Strauss angiitis in a prospective study of 72 patients (22‐75 years old). All the patients were also treated with a corticosteroid (1 mg/kg/ day), and half were included in a randomized trial of cyclophosphamide (2 mg/kg/day during 1 year). Centrifugation was used in 678 plasma exchange sessions (83.4%) and filtration in 128 (15.7%) (no data were available about the technique used in seven cases). The replacement fluid in 745 sessions was 4% albumin and in 115 was freshfrozen plasma; eight patients received both (47 sessions). Two hundred and fifty‐one complications were reported in 60 patients during 206 (25.3%) of the 813 completed exchanges; 47 sessions (5.8%) were temporarily stopped as a result of complications. The most common problems were technical difficulties (in 90 sessions), moderate or severe hypotension (in 52), and allergy to the replacement fluid (in 51). Hepatitis B antigen appeared in one patient. In four patients, plasma exchange was stopped permanently because of the severe side effects. No patient died during a session. Twelve of the 72 patients died during the study, six in each of the two groups. In the group treated by a combination of corticosteroid and plasma exchange, deaths were related to the deleterious effects of the disease itself and occurred after 12.8±11.1 months (1‐26 months). In the group treated by the same combination plus cyclophosphamide, four of the six deaths were due to severe infections, which were related to leukopenia in three patients. They occurred after 4±2 months of treatment (1‐36 months). The side effects and complications due to plasma exchange were usually mild and transient. The only lethal infections were in patients also treated with cyclophosphamide. The possibility that plasma exchange potentiates infectious complications should be considered.
Artificial Heart and Cardiac Transplantation: Report on the First European Combined Procedure
Authors: Unger F. , Chmelizek F. , Jungwirth W. , Koller I. , Laczkovics A. , Lehner L. , Lexer G. , Olsen D. B. , Pohla G. , Schister R. , Wolner E.
Published: July 2010

Abstract: It became necessary to perform a staged procedure by means of total artificial heart followed by cardiac transplantation in a 26‐year‐old, female patient. The Ellipsoidheart, as an artificial heart, fitted excellently in the chest without compromising the surrounding structures. As soon as the patient recovered with the artificial heart, a consecutive transplantation was performed. This first European clinical experience gained confidence and suggests applying more artificial hearts as a bridge towards transplantation.
Optimal Dimensions of Capillary Membranes for Plasma Separation
Authors: Smolik G. , Baurmeister U. , Gurland H. J.
Published: July 2010

Abstract: The work presented in this article examines the relationship between the efficacy of the design (rnembrane consumption) and the design parameters for plasma separation modules. A computer simulation program for the design of hollow fiber modules was developed. It is based on a formula for filtrate flux prediction by Jaffrin. The limiting conditions set by red and white blood cell lysis are also taken into account. The results show that membrane area consumption is strictly related to the internal hollow fiber diameter. Low‐efficiency devices (low infiltrate flux) can be designed nearly optimally, using 330‐μm fibers. On the other hand, for highefficiency devices, our model predicts lowest membrane consumption and, therefore, lowest costs using 220‐μm fiber diameter. Furthermore, the results demonstrate that shear rates in commercially available plasma filters are too low.
A Pilot Study of Piracetam in Cuprophan Hemodialysis
Authors: Grekas Dimitrios , Alivanis Polichronis , Karamouzis Michael , Pyrpasopoulos Marios , Tourkantonis Achilles
Published: July 2010

Abstract: Twelve patients, 8 male and 4 female, aged from 26 to 70 years were studied. They were on hemodialysis (HD) 4 h three times weekly with cuprophan hollow fiber dialyzers (Gambro 120M) and dialysate containing 35 mEq/L of acetate. The study compares two random HD sessions on each patient. Sixty minutes prior to one random session a placebo was administered orally, and prior to another random session piracetam was given at a dose of 8 g. Heparin dosage was not reduced during HD using QB 200 ml, QD 500 ml, and no ultrafiltration. Blood samples for leukocyte and platelet counts, serum C3, arterial paO2 and paCO2, thromboxane‐B2 (TxB2), and β‐thromboglobulin (β‐TG) were taken from the arterial line before and at 15, 60, and 240 min during HD. Leu‐kopenia at 15 min of HD was found to be less severe (p < 0.01) in the piracetam study than in the placebo, whereas platelet count did not change. Serum C3 was slightly increased in both studies. Arterial oxygen was preserved close to the initial levels by piracetam (91.66 mm Hg versus 81.08, p < 0.01 at 60 min, and 93.08 versus 80.17 mm Hg, p < 0.01 at 240 min of HD sessions) but paCO2 did not change significantly. TxB2 increased less with piracetam in comparison to placebo (p < 0.01 or p < 0.001), but (J‐TG was reduced significantly by piracetam at any time during HD (p < 0.001). The above statistical analysis was done by paired t‐test. Using the ANOVA test, significance was found only in plasma TxB2 levels between the two groups (p < 0.001). It is suggested that piracetam is a potent inhibitor of some HD‐associated bioincompat‐ibility parameters.
In‐Vitro Evaluation of a Valveless Cardiac‐Assist Pump
Authors: Einav S. , Elad D. , Avidor J. M. , Stolero D. , Hagigat A. , Barak J. , Vidne B. A.
Published: July 2010

Abstract: Diseases of the cardiovascular system are a major health‐care problem. Nearly 50% of all deaths are due to cardiovascular disease. A number of cardiovascular patients experience heart failure, mostly of the left ventricle, and require some form of mechanical support. Cardiac‐assist devices are used widely in the treatment of patients with damaged heart muscle. Cardiac‐assist devices have been introduced recently to maintain circulation in heart failure patients, until a suitable heart transplant donor is found. Earlier types of left ventricular assist devices were the copulsation and the counterpul‐sation pumps, which increased the efficiency of the vascular system and decreased the workload on the failed heart. In this study, the authors investigated the performance of a valveless cardiac assist device that can be operated in copulsation, counterpulsation, or any intermediate mode with the left ventricle. The device has only one connection to the ascending aorta, no valves, and a common inlet/outlet. The authors measured the hemody‐namic parameters in all modes and have suggested an optimal mode of operation in a left ventricular heart failure model.
Clinical Application of a Self‐Sealing Poly(ether‐urethane) Graft Applicable to Blood Access for Hemodialysis
Authors: Ota Kazuo , Kawai Tatsuo , Teraoka Satoshi , Sasaki Yuri , Nakagawa Yoshihiko
Published: July 2010

Abstract: A poly(ether‐urethane) graft (PEU) has been developed by our group and examined clinically. From July 1986, four straight and 11 loop grafts were implanted in 15 patients on maintenance hemodialysis. One straight and three loop grafts thrombosed between 1–6 months after the operation. One loop graft was ligated to remedy edema caused by a preexisting subclavian vein thrombosis. Angiographic findings of the grafts revealed a smooth positioning of the graft in most of the cases with minimal to moderate stenosis at anastomotic sites. Punctured sites were identified as tiny filling defects on the wall. However, neither stenosis nor aneurysmal dilatation were observed. Specimens of the graft were obtained from three patients to examine histological findings. Neointimal coverage was observed near the anastomotic site in a specimen obtained 6 months after the operation. The bare lu‐minal surface still remained at the center of the graft. No clinical sign of peripheral thrombi was found. In addition to the clinical experience, this study is supplemented with the preliminary result of an animal experiment using a newly modified PEU graft with an open structure on the luminal surface.
Effect of Plasmapheresis on the Liver Uptake of ApoB‐Lipoproteins Labeled with Technetium‐99m
Authors: Anisimova O. Ju. , Konovalov G. A. , Agapov I. I. , Fuki I. V. , Sergienko V. B. , Repin V. S. , Kukharchuk V. V.
Published: July 2010

Abstract: To study liver low density lipoprotein (LDL)‐receptor activity before and after plasmapheresis, [99mTc] very low density lipoprotein (VLDL) was used. Autolo‐gous VLDL was labeled, sterilized by filtration, and administered intravenously to patients under a gamma camera. The uptake of lipoproteins in the liver was measured by scintiscanning. Liver activity curves were generated for each patient. The liver activity in patients with the heterozygous form of familial hypercholesterolemia (FH) and in patients with symptomatic atherosclerosis (SA) without hereditary deficit of LDL receptors was reduced as compared to healthy people. Plasmapheresis enhanced the liver uptake of the 99mTc‐labeled lipoproteins in atherosclerotic patients. Thus, labeled metabolites could presumably be of use in assessing the effect of plasmapheresis on liver function.
Influence of High and Low Wall Shear Rates on the Inhibition of Factor Xa and Thrombin at Surfaces Coated with Immobilized Heparin
Authors: Arnander Claes , Pasche Boris , Kodama Kenji , Rasmuson Anders , Olsson Per
Published: July 2010

Abstract: The thromboresistant function of a surface with end‐point attached heparin is based upon interaction among the immobilized heparin, antithrombin, and at least factor Xa or thrombin. Heparinized arteriovenous shunts were implanted in dogs. By compressing a segment of the shunt, high and low wall shear rate regions were obtained in each shunt. After removal, the tubings were tested for their factor Xa and thrombin inhibitory capacity. It was found that on a molar basis, the factor Xa and thrombin inhibitory capacity were similar in low wall shear rate segments. In high wall shear rate segments, the thrombin inhibitory capacity was decreased, thus indicating that the AT‐mediated inhibition of the serine protease is dependent on the wall shear rate.
Thromboembolic Complications of the Symbion AVAD System
Authors: Icenogle Timothy B. , Smith Richard G. , Cleavinger Marilyn , Vasu M. André , Williams Richard J. , Sethi Gulshan K. , Copeland Jack G.
Published: July 2010

Abstract: The Symbion Acute Ventricular Assist Device (AVAD) System is an experimental paracorporeal pulsatile ventricular assist device (VAD) for single or biven‐tricular assist. Eleven patients were implanted but 2 died within 24 h and were excluded from the study. Nine patients, four with left ventricular assist devices (LVADs) and five with biventricular assist devices (BIVADs), with a mean implant time of 24 days, were studied to determine the incidence and site of thrombus formation within the device and the incidence of thromboembolic complications. Anticoagulation consisted of heparin titrated to keep the partial thromboplastin time (PTT) twice control and dipyridamole 50 to 200 mg q6h p.o. Seven of nine patients (78%) developed thrombus; five had thrombus visible within the clear housing of the device during the implant period, and two patients had thrombus discovered only after VAD explantation. Common sites of formation were the diaphragm‐housing junction, the housing near the outflow orifice, and the de‐airing port. Three patients with thrombus developed thromboembolic complications; two suffered strokes and one had multiorgan emboli. The Symbion AVAD System has significant thrombogenic properties that may limit its clinical application.
General Planning of an Artificial Organ Center
Authors: Vanholder R. , Ringoir S.
Published: July 2010

Abstract: There is an increasing need for research and development centers to deal with design and evaluation of organ replacement systems, the improvement of older devices, and the study of biocompatibility problems. Special attention, in this article, is focused on the determinant role of the background of the investigators involved in a given center and the selection of research programs to be pursued. Financial and architectural aspects are discussed in general terms. Appropriate planning of artificial organ centers should allow conceptualizing research and development that will exert a practical impact on patient care locally and worldwide.
Ex Vivo Evaluation in Normal Dogs of Insulin Released by a Bioartificial Pancreas Containing Isolated Rat Islets of Langerhans
Authors: Lepeintre J. , Briandet H. , Moussy F. , Chicheportiche D. , Darquy S. , Rouchette J. , Imbaud P. , Duron J. J. , Reach G.
Published: July 2010

Abstract: In bioartificial pancreatic systems, isolated islets of Langerhans are protected against immune rejection by an artificial membrane, permeable to glucose and insulin, but not to immunoglobulins and lymphocytes. Some of these devices, referred to as vascular systems, are set up to be connected to a vascular site in the recipient, with blood circulating in contact with one side of the membrane, and the islets on the other side. Such a bioartificial pancreas, containing isolated rat islets of Langerhans, was connected to an arteriovenous shunt of a normal anesthetized dog. The aim of this experiment was to investigate the kinetics of the insulin secretory response of the system to a glucose load. Glucose was infused upstream of the system, increasing the glucose concentration inside the bioartificial pancreas from 7 to 14 mmol/1, without altering the blood glucose concentration of the dog. Insulin concentration was determined simultaneously upstream and downstream of the bioartificial pancreas. Insulin production was calculated by multiplying the difference between these values by the blood flow rate. Blood flow rate (Q) was estimated from the change in the glucose concentration produced by the glucose infusion using a mass transfer analysis derived from Fick's principle. Insulin production increased from 20 ± 8 to 59 ± 15 μU/100 islets/min within 15 min following the beginning of the stimulation (n = 6, p < 0.05). Five min after the end of the stimulation, insulin production decreased from 75 ± 13 to 50 ± 9 μU/100 islets/min (p < 0.05) to reach the basal level (21 ± 3 μU/100 islets/min) 30 min after the end of the glucose stimulation. This rapid response to changes in blood glucose concentration, demonstrated ex vivo with the device connected directly to an arterial vessel, is consistent with the establishment of closed‐loop insulin delivery by this bioartificial pancreas.
Fibronectin Coating of Expanded Polytetrafluoroethylene (ePTFE) Grafts and Its Role in Endothelial Seeding
Authors: Vohra R. K. , Thompson G. J. L. , Sharma H. , Carr H. M. H. , Walker M. G.
Published: July 2010

Abstract: Although fibronectin's role as a matrix to improve endothelial seeding has been demonstrated by other workers, the optimum concentration for use has never been described. Attachment of fibronectin to expanded polytetrafluoroethylene (ePTFE) was measured, using 125I‐radiolabeled protein, at different concentrations and for different time periods. The absolute amount of fibronectin bound to the graft increased with the concentrations used in coating (p < 0.001) and also with time (p < 0.01); e.g., at 50 μg/ml, 90 min of incubation produced a molecular attachment of 4.0 × 1011/cm2 of graft.

However, its percentage attachment decreased with a rise in concentration (p < 0.001). After an initial loss of 22% in 30 min, the fibronectin‐graft bond was found to be stable when exposed to a shear stress produced by flow at 200 ml/min. No significant difference in the cell adherence could be found in grafts coated with fibronectin concentrations of 50, 150, and 250 μg/ml, although it was significantly less at 10 and 25 μg/ml (p < 0.05).
A Pediatric Ventricular Assist Device: Its Development and Experimental Evaluation of Hemodynamic Effects on Postoperative Heart Failure of Congenital Heart Diseases
Authors: Taenaka Yoshiyuki , Takano Hisateru , Noda Hiroyuki , Kinoshita Masayuki
Published: July 2010

Abstract: To evaluate the effectiveness of a pediatric ventricular assist device (VAD), hemodynamic effects of the VAD were investigated experimentally in two types of postoperative profound heart failure models of congenital heart disease. In the model I Fontan or modified Fontan operation model, right ventricular pump function was excluded surgically and a shunt between the right atrium and the pulmonary artery was constructed in four dogs. With a VAD between the left atrium and the aorta, pressure gradient across the lung and the cardiac output in creased. Right ventricular failure was induced surgically and high pulmonary vascular resistance was made by injection of glass beads in five dogs in model II. Cardiac output increased and the right atrial pressure decreased when a VAD between the right atrium and the pulmonary arterial trunk was activated. In conclusion, the VAD will become a promising modality to manage pediatric profound heart failure cases.
Microbial and Endotoxin Contamination in Water and Dialysate in the Central United States
Authors: Klein Elias , Pass Ted , Harding George B. , Wright Rita , Million Carolyn
Published: July 2010

Abstract: The purified water supplies and randomly selected dialysates of 51 chronic and acute dialysis centers in the central United States were surveyed to assess the relative risks to dialysis patients from microbial and endotoxin contamination. A culture medium more sensitive than those generally employed in routine quality assurance assays was used for recovery of bacteria from water. With this medium, 35.3% of the water samples and 19% of the dialysate samples were out of compliance with the Association for the Advancement of Medical Instrumentation (AAMI) standards: 200 and 2,000 colony forming units (CFU)/ml, respectively. There was no correlation observed between the type of water purification system or the frequency of disinfection of the system and the bacterial and endotoxin contamination levels. There was also no correlation found between the bacterial and fungal

CFU per ml and the endotoxin concentration per ml (EU/ ml). It is recommended that more sensitive culturing methods be used to provide adequate bacterial monitoring of dialysate center water supplies. Dialysis centers should monitor endotoxin in dialysate on a regular schedule and immediately after any endotoxemic‐like patient reactions. Yeast and fungi were observed in 10% and 64% of the water systems, respectively. Dialysate was contaminated by yeast and fungi in 30% and 70% of the centers, respectively. The concentrations of these microbes in both fluids were much lower than bacteria. However, they were observed often enough to warrant further investigation of their impact on the well‐being of dialysis patients.
Artificial Blood Circulation: Stabilization, Physiological Control, and Optimization
Authors: Lerner Alexander Y.
Published: July 2010

Abstract: The requirements for creating an efficient Artificial Blood Circulation System (ABCS) have been determined. A hierarchical three‐level adaptive control system is suggested for ABCS to solve the following problems: stabilization of the circulation conditions, left and right pump coordination, physiological control for maintaining a proper relation between the cardiac output and the level of gas exchange required for metabolism, and optimization of the system behavior. The adaptations to varying load and body parameters will be accomplished using the signals which characterize the real‐time computer‐processed values of correlations between the changes in hydraulic resistance of blood vessels, or the changes in aortic pressure, and the oxygen (or carbon dioxide) concentration.
Portable Closed Loop Feedback System for Control of the Blood Glucose Level in the Pig
Authors: Pierzynowski S. G. , Håkansson H. , Ljunggren L. , Mårtensson L. , Olsson L.
Published: July 2010

Abstract: To establish the difference in glucose consumption of healthy compared to diabetic pigs, a transportable system for the feedback control of insulin and glucose was used in conscious pigs. The system for controlling glucose levels, as well as glucose consumption, was easy to use and adjusted smoothly to rapid changes in insulin level. Five days prior to the first day of experiment, healthy animals were prepared with intravenous jugular catheters tunneled subcutaneous to the neck. On the first day of experiment, measurements of glucose were continuously taken before and after food ingestion. The animals were rendered diabetic after 2 days using Alloxan and streptozotocin. The measurements were then repeated. To be able to obtain constant glucose levels of—3 mol during both fasting and postprandial periods requires only small glucose adjustment infusion in the diabetic pigs, as opposed to healthy ones. Using the described system, it would be possible to evaluate subclinical diabetes and control unstable diabetics with different therapeutic regimes.
Chemical Modification of Cellulosic Membranes and Their Blood Compatibility
Authors: Paul Dieter , Malsch Günter , Bossin Elke , Wiese Frank , Thomaneck Uwe , Brown Gail S. , Werner Heinz , Falkenhagen Dieter
Published: July 2010

Abstract: Blood compatibility is determined by interactions at the blood‐material interface that depend on the material surface chemical structure. Through selective modifications of the chemically reactive hydroxyl groups of cellulose, the aim was to improve the biocompatibility of cellulose membranes. The number of potentially reactive hydroxyl groups on the cellulose membrane surface were reduced through isocyanate cross‐links or through the introduction of hydrophilic, hydrophobic, or ionic functionalities by graft copolymerization. To assess blood compatibility, levels of C3a desArg were determined in plasma after membrane contact. Using the electrophoretic mobility test, the release of cytokines were measured after in‐vitro incubation of mononuclear cells with membranes. Adsorption of 131J‐human fibrinogen was additionally investigated. With respect to the biocompatibility parameters selected, the modified cellulose membranes show improved in‐vitro blood compatibility in comparison to unmodified cellulose membranes.
Skeletal Muscle Ventricles: Update After 18 Months in Circulation
Authors: Ruggiero Renato , Niinami Hiroshi , Pochettino Alberto , Hammond Robert L. , Hooper Timothy L. , Huiping Lu , Anderson David R. , Spanta Ali D. , Stephenson Larry W.
Published: July 2010

Abstract: Skeletal muscle ventricles (SMVs) have been constructed from canine latissimus dorsi muscle and connected to the aorta as aortic diastolic counterpulsators. Presently one dog remains alive and well with an SMV that has been functioning continuously in circulation for 18 months, without evidence of thromboembolic complications. SMVs are able to perform cardiac–type work with an output equal to that of the left ventricle at physiologic preloads, when tested with a mock circulation device in our laboratory. SMVs have been used for right sided cardiac assist. In acute experiments these ventricles have functioned effectively, bypassing the right side of the heart for up to 8 h. Most recently we have tested SMVs using them chronically to pump blood in the right–sided circulation, and at the time of writing they have been shown to function effectively in this configuration for up to 18 days. SMVs may be used in the future as a method of treating patients with left– or right–sided heart failure.
Extracorporeal Mechanical Pulsatile Pump and Its Significance for Myocardial Function Recovery and Circulatory Support
Authors: Konstantinov B. A. , Dzemeshkevich S. L. , Rogov K. A. , Nenukov A. K. , Budaev V. N. , Palulina M. V. , Movsesov R. V. , Egorov T. L. , Kozlov A. V. , Burtsev P. U. , Meluzov K. L.
Published: July 2010

Abstract: The authors performed 12 acute (on dogs) and 12 chronic (on calves) assisted circulation experiments with the use of the total extracorporeal mechanical pump (TEMP) artificial ventricles. The functional morphological research of the myocardium suggests that in addition to the possibility of the biological heart function full replacement, the artificial ventricle also helps recover dam ages in both the myocardial infarction and distal zones. The critical time period up to the onset of artificial circulation is not more than 2 h, and after that myocardial changes are irreversible.
Characterization of Rehydrated Gelatin Gels
Authors: Emoto Hideto , Kambic Helen , Chen Ji–Feng , Nose Yukihiko
Published: July 2010

Abstract: Five percent glutaraldehyde cross–linked gels have shown excellent blood compatibility as coatings for cardiac prostheses. A method was developed for producing thin dehydrated coatings using a proprietary dehydration procedure and ethylene oxide (EO) sterilization. The swollen surfaces of rehydrates versus wet (original) gels were compared. Within 30 min of saline rehydration, dry 30–50–μm films on textured surfaces became smooth, uniform, and comparable to original gelatin gels. Mechanical test results after rehydration showed values for strain remain unchanged (39.3 + 10.0 to 40.0 + 7.8%), but stress increased (2.79 + 1.21 to 4.22 + 1.60 dyne/cm2; p < 0.01). The contact angle data reported ±C values of 26.1 and 30.4 dyne/cm for original and rehydrated gels. Using a coulometric titrimeter, the measured water content of original gels was reduced from 85 to 3.4% after drying. Dried and saline rehydrated gels had a 73.2% moisture content. Gels shrank 8.8% of their original length after rehydration; however, the thickness of all pump coatings remained stable. Two–hour incubations with bovine platelet rich plasma showed no differences in platelet reactivity or morphology when compared to original gels. Light microscopy and scanning electron microscopy (SEM) showed no evidence of gel cracking or surface defects after pump endurance testing for 3 and 5 weeks. The process of dehydration eliminates the wet storage and sterility problems of such hydrogels and provides a stable film coating for a variety of blood–contacting substrates.
24–Hour Preservation of Isolated Rat Hearts Perfused with Pyridoxalated Hemoglobin Polyoxyethylene Conjugate (PHP) Solution at Low Temperature
Authors: Iwasaki Shuichi , Araki Haruo , Miyauchi Yoshimasa , Nishi Katsuhide
Published: July 2010

Abstract: We examined the effects of long–term perfusion with pyridoxalated hemoglobin polyoxyethylene conjugate (PHP) solution on cardiac function of isolated rat hearts. Hearts were perfused with oxygenated Krebs–Henseleit (K–H) solution containing 3% PHP or hydrox–yethyl starch (HES) at a constant pressure of 13 mm Hg for 24 h at 15°C. After 24 h preservation, hearts were rewarmed with K–H solution. Heart rate (HR) in PHP–preserved hearts was almost the same as control and cardiac contractility was maintained at 70% of control, but coronary outflow decreased to about 50% of control. No edema developed in the PHP group. Addition of a Ca2+ antagonist, diltiazem, inhibited the elevation of the enddiastolic pressure significantly. In HES–preserved hearts, HR did not recover to control levels, but there was no significant difference in cardiac contractility between PHP– and HES–perfused hearts. The results demonstrate that isolated hearts can be preserved by perfusion with PHP solution under hypothermic conditions for 24 h and suggest that PHP solution would be useful for a perfusate of isolated organs and tissues for preservation.
Myointimal Hyperplasia: Pathogenesis and Implications. 2. Animal Injury Models and Mechanical Factors
Authors: Painter Thomas A.
Published: July 2010

Abstract: Arterial wall injury either by balloon catheter, drying, or scraping results in a denudation of endothelial cells (EC) and a subsequent proliferation of smoothmuscle cells (SMC). The degree of SMC proliferation appears to be dependent on the degree of initial injury and not to the loss of the overlying endothelium. Successful reendothelialization of denuded areas depends on the size of the denuded segment as well as SMC–EC interactions. Prolonged exposure of SMC to serum substances results in inhibition of EC regrowth, the production of prostacyclin by SMC, and the development of a thromboresistant surface. Heparin appears to inhibit SMC proliferation in vivo (as well as in vitro), an effect that is independent of platelet SMC interaction. EC–derived heparin in vivo may also result in inhibition of SMC proliferation. Platelets may play an important role in the early response to arterial injury and development of myointimal hyperplasia (MIH), but their long–term role appears to be minor. Antiplatelet agents have widely varying species–dependent

effects on platelets and platelet–vessel wall interactions, but in specific circumstances they may inhibit MIH. The precise role of steroid drugs and immunosuppression on MIH in arterial injury models awaits further study. The role of lipoproteins in MIH is unclear; however, the inhibition of MIH by ±–3 fatty acids in vivo as well as their inhibition of platelet–derived growth factor production by EC in vitro implies a regulatory role. Acute hypertension results in a marked proliferation of EC and SMC in vivo and enhances the proliferative response to injury as well. Low wall shear stress, turbulence, and boundary layer separation all increase EC turnover, a likely influence on EC growth factor production. The compliance mismatch resulting from graft–artery anastomoses, injury, and endarterectomy results in locally increased cyclical stretch, which may predispose to SMC proliferation.
Is A Totally Implantable Artificial Heart Realistic?
Authors: Nose Yukihiko
Published: July 2010

Abstract: The incidence of local infection that occurred after the implantation of the intrathoracic Jarvik 7 total artificial heart (5–7 TAH) in patients was a major problem of this cardiac prosthesis. Infection rates increased when the 5–7 TAH was implanted for longer periods of time, which was contrary to the results that were obtained by the implantation of the left ventricular assist devices (LVAD) either in the abdominal cavity or in the abdominal wall. Currently, the general belief is that the implantation of a cardiac prosthesis inside of the chest cavity is not safe, due to higher rates of infection. Thus, Part I of this paper deals with the question: “Is a total artificial heart physiologically acceptable?” We believe structural differences of the J‐7 TAHs and other LVADs are an important part of the problem. The J‐7 TAH is a volumetrically dynamic pump, and the other LVADs are a volumetrically fixed stationary pump. Based upon experiences of this investigator, intrathoracic implantation of a smooth surface pulsating device (or a volumetrically dynamic pump) generated persistent local inflammatory reactive tissues directly adjacent to the device. These tissue capsules were nonadherent to the device, and therefore may produce an ideal environment for allowing bacteria to grow. The findings were opposite to those for a non‐pulsating surface pump inside the chest cavity. Part II of this paper discusses the question: “Is a totally implantable artificial heart technically achievable?” Many technical probiems for the totally implantable TAH were already resolved during the development program of the totally implantable LVAD. However, there are three TAH specific problems that remain to be solved before achieving a clinically useful totally implantable TAH system. They are (a) antonical compatibilities of the TAH system; (b) reliable control of the TAH system, (c) reliable and effective long‐term operation of the TAH system. We have resolved the anatomical problem by the integral design of the pump‐actuator system. Overall size of the hard shell Baylor TAH system is 510 cm3 with a diameter of 97 mm and a width of 82 mm. Its stoke volume was reduced to 63 cm3. The stable and reliable control of TAH performances was established by the three sets of Hall effect sensors with left master alternate mode of pumping. No physiological parameter was used as a feedback signal. Reliable long‐term operation of the TAH system was established by the electromechanical actuation system. A simple drive mechanism with commercially available components and subsystems was used. Components are chosen from those already of proven reliability and long life. Blood compatible features was established by dry biolized coating for the blood contacting surface of the pump. The preceding features of the totally implantable TAH make this author believe that a totally implantable artificial heart is realistic and achievable within the not too far distant future.
Molecular Bioengineering of Biomaterials in the 1990s and Beyond: A Growing Liaison of Polymers with Molecular Biology
Authors: Hoffman Allan S.
Published: July 2010

Abstract: An important trend in biomaterials research and development is the synthesis of polymers that combine capabilities of biologic recognition (biomimetic) with special physicochemical properties of the synthetic polymer system. Another important trend in such “molecular bioengineering” is to develop, perhaps via computer‐aided molecular design, new artificial biomimetic systems by exact placement of functional groups on rigid polymer backbones, cross‐linked structures, or macromolecular assemblies. In this way, biocatalytic functioning or biore‐cognition similar to enzymes and antibodies can be achieved without the inherent instability often encountered with the native biomolecules or assemblies. Perhaps the most exciting trend in biomaterials research and development is the availability of new biomolecules, e.g., via protein engineering and of hardy cells with specific biofunctions and bioresponses that can be tailored to specific medical or biotechnological needs. The wide variety of ways that such biomolecules and cells can be combined with polymeric biomaterials provides tremendously exciting opportunities for the biomaterials scientists and engineers. In addition to these synthetic approaches, new and exciting analytical tools, such as the scanning tunneling microscope and the atomic force microscope, are permitting study on a molecular scale of individual and small clusters of proteins and other biomolecular assemblies on surfaces. Cell attachments and spreading may also be visualized at various depths within the cell using the confocal laser microscope. Such analytical techniques can lead to important new knowledge about biologic interactions with biomaterials and, therefore, to development of even more biocompatible implants and devices. This paper overviews the present state of polymeric biomaterials and highlights the important and exciting opportunities generated by the liaison of these materials with molecular biology.
Intravascular Oxygenator: A New Alternative Method for Augmenting Blood Gas Transfer in Patients With Acute Respiratory Failure
Authors: Mortensen J D.
Published: July 2010

Abstract: A unique hollow fiber membrane oxygenator (IVOX) has been developed, which is inserted into the vena caval blood stream to transfer O2/CO2 to/from circulating blood in an intact subject without involving the natural lungs. Extensive laboratory testing has demonstrated that the device can transfer significant quantities of O2 and CO2 for up to 3 weeks without significant harmful sequelae or complications. Clinical trials are in progress under FDA supervision, in which IVOX has been utilized to date in 56 patients with ARDS. Preliminary findings indicate that risks and hazards from IVOX are nil, and evidence of benefit to the patient has been demonstrated in 86% of the patients. At this time, clinical utilization of IVOX is in the experimental, data collecting mode to determine its proper role or niche as a method for temporary augmentation of blood gas transfer in patients with advanced acute respiratory failure.
Hematologic and Hemostatic Complications Associated with Long‐Term Use of Total Artificial Heart: Clinical and Experimental Observations
Authors: Al‐Mondhiry Hamid , Pae Walter E. , Rosenberg Gearson , Pierce William S.
Published: July 2010

Abstract: The two most serious complications associated with long‐term use of a total artificial heart (TAH) are thromboembolism and infection. In this article, we review our experience in one patient implanted with a pneumatic TAH for 396 days, and in 24 calves implanted with the same type of device for 70 to 353 (median 150) days. During his survival with the TAH, our patient suffered several thromboembolic episodes despite adequate anti‐coagulation with warfarin. Autopsy showed widespread thrombotic lesions, mostly in the brain. Throughout his survival, the patient had markedly elevated plasma β‐thromboglobulin and fibrinopeptide A levels, indicating sustained activation of platelets and the coagulation system secondary to blood contact with the artificial surface. Long‐term use of TAH in calves causes significant mechanical hemolytic anemia and a small reduction in the total leukocyte and neutrophil counts. The platelet count normalized to preirnplantation levels by 25 to 35 weeks. At autopsy, thrombotic lesions and organ infarction were noted in 13 calves, and major septic complications were documented in 10 animals. Although impressive gains in the clinical and experimental use of TAH were achieved during the last 15 years, thromboembolism and infection remain challenging problems.