bluuebunny/crossref_metadata_2025 huggingface dataset:
Cytokine Induction in Patients Undergoing Regular Online Hemodiafiltration Treatment
Authors: Vaslaki Lajos , Weber Christoph , Mitteregger Regina , Falkenhagen Dieter
Published: March 2003

Abstract: End‐stage renal disease (ESRD) patients are known to suffer from chronic inflammation as the result of an ongoing subacute cytokine induction, which may contribute considerably to dialysis‐related, long‐term morbidity and mortality. Preparation of infusate from cytokine‐inducing dialysis fluid and its administration in large quantities as well as the use of high‐flux membranes bear the risk of aggravating the chronic inflammatory response among online hemodiafiltration (online HDF) patients. In order to assess the inflammatory risk associated with online HDF, we compared the cytokine induction profile of ESRD patients receiving either online HDF or low‐flux hemodialysis (low‐flux HD). Specifically, we measured spontaneous and lipopolysaccharide (LPS)‐stimulated tumor necrosis factor α (TNFα) and interleukin‐1 receptor antagonist (IL‐1Ra) release during ex vivo incubation of whole blood. Ultrapure dialysis fluid and polysulfone membranes were used for both treatment modalities. LPS‐stimulated release of TNFα and IL‐1Ra was elevated for both online HDF and low‐flux HD patients compared to healthy individuals (TNFα: 2,336 ± 346 and 2,192 ± 398 versus 1,218 ± 224 pg/106 white blood cells [WBC]; IL‐1Ra: 2,410 ± 284 and 2,326 ± 186 versus 1,678 ± 219 pg/106 WBC). Likewise, spontaneous production of TNFα, but not IL‐1Ra, was higher in online HDF and low‐flux HD patients than in normal controls (37 ± 32 and 22 ± 19 versus 0.8 ± 0.3 pg TNFα/106 WBC). There was no difference in spontaneous and LPS‐stimulated cytokine release between both dialysis groups. In addition, intradialytic cytokine induction was not significant for either treatment modality as spontaneous and LPS‐stimulated cytokine release were not increased postdialysis. These findings indicate that online HDF does not contribute to chronic leukocyte activation and, consequently, does not place ESRD patients at greater risk with respect to inflammatory morbidity and mortality.
Development of Catheters With Low Fiber Background Signals for Raman Spectroscopic Diagnosis Applications
Authors: De Lima Carlos J. , Sathaiah Sokki , Silveira Landulfo , Zângaro Renato A. , Pacheco Marcos Tadeu T.
Published: March 2003

Abstract: Utilization of optical‐fiber catheters can turn the Raman spectroscopy system into a powerful remote biomedical diagnostic probe. An in vivo (a qualitative and a quantitative) biochemical diagnosis of biotissues is possible by developing the Raman‐fiber probes with a good flexibility and less background signals generated in the probes themselves. Considering the isotropic nature of Raman scattering, the amount of Raman signal guided through the fiber is expected to depend on the numerical aperture (NA) of the fiber. To study the dependence for catheter probes experimentally, various flexible probes (with small diameter fibers) with different combinations of numerical apertures and with different assembling materials (biocompatible) have been developed. The catheter probes have been characterized by collecting the near infrared excited Raman scattered light from cholesterol powder. The results demonstrate that the catheters with a combination of lower NA (0.12) fibers used for laser excitation and relatively higher NA (0.22) fibers for Raman signal collection will have lower background signals generated in the probes. Furthermore, the catheters with a black Teflon tubing cover and black epoxy resin adhesives were found to give better results.
Preparation and Characterization of Collagen‐Elastin Matrices From Blood Vessels Intended as Small Diameter Vascular Grafts
Authors: Goissis Gilberto , Suzigan Sueli , Parreira Diderot Rodrigues , Maniglia José Vitor , Braile Domingo Marcolino , Raymundo Selma
Published: March 2003

Abstract: This study describes the selective removal of cell and cell residues from small and large diameter blood vessels for the preparation of tubular collagen:elastin matrices intended for small diameter vascular prosthesis. The results showed that total or partially devitalized collagen:elastin matrices may be conveniently prepared without denaturation of the collagen:elastin matrix with a high degree of preservation of the proteins. The efficiency of cell removal and the extent collagen and elastic fiber preservation were dependent on the segment and the type of blood vessel under study, with arteries characterized by a higher susceptibility of cell removal and better preservation of the collagen‐elastin matrix.
Transaortic Inflow and Outflow Cannula for Centrifugal Mechanical Assistance
Authors: Kalangos Afksendiyos
Published: March 2003

Abstract: A specific cannula allowing single site transaortic inflow and outflow cannulation for centrifugal assist devices is described. The cannula is inserted through a straight 18 mm collagen coated Dacron tube anastomosed to the anterior aspect of the ascending aorta. The inflow conduit of the cannula is positioned into the left ventricle through the aortic valve, and the end hole of the outflow conduit is positioned in the ascending aorta. The cannula was evaluated in vivo in 3 adult pigs by the institution of a centrifugal pump for left ventricular support. Optimal flow varied between 5 and 6 L/min and mean aortic pressure between 55 and 70 mm Hg throughout the 3 days of left ventricular support. Recently, we employed this cannula in a patient who was not able to be weaned from cardiopulmonary bypass for the institution of left ventricular support using a centrifugal pump. The cannula provided effective inflow and outflow drainage with an optimal flow of 5.2 L/min throughout the 72 h of support. The patient was successfully weaned from support on the fourth postoperative day. This rational transaortic approach of cannulation using this specific cannula is a refined implantation technique which allows direct left ventricular inflow drainage, reduces the time of implantation, spares left ventricular myocardium, avoids bleeding that is sometimes encountered at other cannulation sites, and avoids compression of the heart by cannulas.
Evaluation of Cardiac Function During Left Ventricular Assist by a Centrifugal Blood Pump
Authors: Kikugawa Daiki
Published: March 2003

Abstract: In this study, the effects on varying cardiac function during a left ventricular (LV) bypass from the apex to the descending aorta using a centrifugal blood pump were evaluated by analyzing the left ventricular pressure and the motor current of the centrifugal pump in a mock circulatory loop. Failing heart models (preload 15 mm Hg, afterload 40 mm Hg) and normal heart models (preload 5 mm Hg, afterload 100 mm Hg) were simulated by adjusting the contractility of the latex rubber left ventricle. In Study 1, the bypass flow rate, left ventricular pressure, aortic pressure, and motor current levels were measured in each model as the centrifugal pump rpm were increased from 1,000 to 1,500 to 2,000. In Study 2, the pump rpm were fixed at 1,300, 1,500, and 1,700, and at each rpm, the left ventricular peak pressure was increased from 40 to 140 mm Hg by steps of 20 mm Hg. The same measurements as in Study 1 were performed. In Study 1, the bypass flow rate and mean aortic pressure both increased with the increase in pump rpm while the mean left ventricular pressure decreased. In Study 2, a fairly good correlation between the left ventricular pressure and the motor current of the centrifugal pump was obtained. These results suggest that cardiac function as indicated by left ventricular pressure may be estimated from a motor current analysis of the centrifugal blood pump during left heart bypass.
VentrAssist Hydrodynamically Suspended, Open, Centrifugal Blood Pump
Authors: Watterson Peter A. , Woodard John C. , Ramsden Victor S. , Reizes John A.
Published: March 2003

Abstract: A novel design is presented for an implantable centrifugal blood pump in which hydrodynamic forces acting on tapered edges of thick blades are used to suspend the impeller. The pump has no shaft, seals, or “spiders” and has clean flow lines with no stagnant zones. At 5 L/min and 100 mm Hg differential pressure, the measured hemolysis was in the range NIH 0.002–.005 g/100 L and the system efficiency was 19%.
Multisorbent Plasma Perfusion in Fulminant Hepatic Failure: Effects of Duration and Frequency of Treatment in Rats with Grade III Hepatic Coma
Authors: Ryan Calvin J. , Anilkumar Thapasimuthu , Ben‐Hamida Abdul J.A. , Khorsandi Shirin E. , Aslam Mohammed , Pusey Charles D. , Gaylor John D.S. , Courtney James M.
Published: March 2003

Abstract: Using the model of galactosamine‐induced fulminant hepatic failure in the rat, the effects of multisorbent plasma perfusion over Asahi uncoated spherical charcoal, Plasorba (BR‐350) resin, and an endotoxin removing adsorbent (polymyxin B‐sepharose) were determined in Grade III hepatic coma animals by studying survival as influenced by timing, duration, and frequency of treatment. The effects of treatment on liver cell proliferation and endotoxin removal also were examined. The results demonstrate that duration and frequency of treatment are major contributing factors in the successful application of nonbiological membrane‐based multisorbent liver support systems. Examination of the regenerative activity in the liver indicates an enhanced proliferative response following multisorbent plasma perfusion compared with untreated fulminant hepatic failure (FHF) paired controls. Utilizing an endotoxin removal adsorbent alone, a marked reduction in systemic levels of endotoxin in FHF was demonstrated compared with nonperfused FHF paired controls. Despite current emphasis on bioartificial liver support systems, plasma purification by multisorbent systems offers a simple method for the removal of circulating toxic metabolites in general together with specific toxin removal.
Change in Vasoconstrictive Function During Prolonged Nonpulsatile Left Heart Bypass
Authors: Nishinaka Tomohiro , Tatsumi Eisuke , Nishimura Takashi , Shioya Kyoko , Ohnishi Hiroyuki , Taenaka Yoshiyuki , Takano Hisateru
Published: March 2003

Abstract: We investigated changes in vasoconstrictive function accompanying prolonged nonpulsatile left heart bypass (NLHB). After 2‐week pulsatile left heart bypass (PLHB) in 11 goats, NLHB was conducted for another 4 weeks (Group N) in 6 goats. In the other 5 goats, PLHB was continued for another 4 weeks (Group P). Systemic vascular resistance at rest (rSVR) was measured on the last days of the second and sixth postoperative week (W2 and W6, respectively). Subsequently, phenylephrine was injected, and the maximum values (SVRmax) and the maximum increasing change in SVR (ΔSVR) were measured. No significant difference was observed in rSVR between groups at W2 or W6. The SVRmax and the ΔSVR at W2 were consistent in both groups. However, at W6, the SVRmax and the ΔSVR of Group N were significantly lower than those of Group P. In conclusion, prolonged NLHB caused a significant decrease in the SVR response to phenylephrine, indicating a dimunition of vasoconstrictive function.
The HeartMate III: Design and In Vivo Studies of a Maglev Centrifugal Left Ventricular Assist Device
Authors: Loree Howard M. , Bourque Kevin , Gernes David B. , Richardson J. Scott , Poirier Victor L. , Barletta Natale , Fleischli Andreas , Foiera Giampiero , Gempp Thomas M. , Schoeb Reto , Litwak Kenneth N. , Akimoto Takehide , Kameneva Marina , Watach Mary J. , Litwak Philip
Published: March 2003

Abstract: A compact implantable centrifugal left ventricular assist device (LVAD) (HeartMate III) featuring a magnetically levitated impeller is under development. The goal of our ongoing work is to demonstrate feasibility, low hemolysis, and low thrombogenicity of the titanium pump in chronic bovine in vivo studies. The LVAD is based on so‐called bearingless motor technology and combines pump rotor, drive, and magnetic bearing functions in a single unit. The impeller is rotated (θz) and levitated with both active (X, Y) and passive (Z, θx, θy) suspension. Six prototype systems have been built featuring an implantable titanium pump (69 mm diameter, 30 mm height) with textured blood contacting surfaces and extracorporeal electronics. The pumps were implanted in 9 calves (≤100 kg at implant) that were anticoagulated with Coumadin (2.5 ≤ INR ≤ 4.0) throughout the studies. Six studies were electively terminated (at 27–61 days), 1 study was terminated after the development of severe pneumonia and lung atelectasis (at 27 days) another study was terminated after cardiac arrest (at 2 days) while a final study is ongoing (at ≈100 days). Mean pump flows ranged from 2 to 7 L/min, except for brief periods of exercise at 6 to 9 L/min. Plasma free hemoglobin ranged from 4 to 10 mg/dl. All measured biochemical indicators of end organ function remained within normal range. The pumps have met performance requirements in all 9 implants with acceptable hemolysis and no mechanical failures.
Automatic Detection and Classification of Abnormalities for Artificial Hearts Using a Hierarchical Self‐Organizing Map
Authors: Wang Xian‐Zheng , Yoshizawa Makoto , Tanaka Akira , Abe Ken‐ichi , Yambe Tomoyuki , Nitta Shin‐ichi
Published: March 2003

Abstract: A hierarchical self‐organizing map (SOM) has been developed for automatic detection and classification of abnormalities for artificial hearts. The hierarchical SOM has been applied to the monitoring and analysis of an aortic pressure (AoP) signal measured from an adult goat equipped with a total artificial heart. The architecture of the network actually consists of 2 different SOMs. The first SOM clusters the AoP beat patterns in an unsupervised way. Afterward, the outputs of the first SOM combined with the original time‐domain features of beat‐to‐beat data are fed to the second SOM for final classification. Each input vector of the second SOM is associated with a class vector. This class vector is assigned to every node in the second map as an output weight and learned according to Kohonen's learning rule. Some experimental results revealed that a certain abnormality caused by breakage of sensors could be identified and detected correctly and that the change in the state of the circulatory system could be recognized and predicted to some extent.
The Bradykinin Response and Early Hypotension at the Introduction of Continuous Renal Replacement Therapy in the Intensive Care Unit
Authors: Stoves J. , Goode N.P. , Visvanathan R. , Jones C.H. , Shires M. , Will E.J. , Davison A.M.
Published: March 2003

Abstract: We assessed the relationship of certain clinical variables (including bradykinin [BK] release and dialysis membrane) to initial mean arterial pressure (MAP) reduction in 47 patients requiring continuous renal replacement therapy (CRRT) in an intensive care unit. The pretreatment MAP was 84 ± 14 mm Hg for the group as a whole. The initial MAP reduction was 11.5 (7–20) mm Hg, occurring 4 to 8 min after connection. MAP reduction was 9 (6–15) mm Hg with polyacryonitrile (PAN) membranes versus 14 (5‐19) mm Hg with polysulfone (PS) (not significant). There were positive correlations between MAP reduction and BK concentration at 3 (BK3; r = 0.58, p < 0.01) and 6 (BK6; r = 0.67, p < 0.001) min with PAN but not with PS. A greater reduction in MAP was seen in patients who were not receiving inotropic support (Mann‐Whitney test, p < 0.01). BK3 and BK6 values for the PAN and PS groups were not significantly different. However, BK concentrations greater than 1,000 pg/ml were only seen with PAN (6 patients, MAP reduction 27 [17–31] mm Hg). There were positive (albumin) and negative (age; acute physiology, age, and chronic health evaluation score; C‐reactive protein [CRP]; calcium) correlations with BK3/BK6 in the PAN and PS groups, some of which (albumin, CRP) reached statistical significance. In summary, MAP reduction at the start of CRRT correlates with BK concentration. The similarity of response with PAN and PS suggests an importance for other clinical factors. In this study, hemodynamic instability was more likely in patients with evidence of a less severe inflammatory or septic illness.
Effects of Left Ventricular Assist Device on Cardiac Function: Experimental Study of Relationship between Pump Flow and Left Ventricular Diastolic Function
Authors: Saito Akira , Shiono Motomi , Orime Yukihiko , Yagi Shinya , Nakata Kin‐ichi , Eda Kunihiro , Hattori Tsutomu , Funahashi Michio , Taniguchi Yoshiki , Negishi Nanao , Sezai Yukiyasu
Published: March 2003

Abstract: The left ventricular assist device (LVAD) with centrifugal pump has two characteristics. One is a pump flow wave of the centrifugal pump, consisting of the pulsatile flow of the native heart and the nonpulsatile flow of the centrifugal pump. The other is that the centrifugal pump fills from the native heart not only in the systolic phase, but also in the diastolic phase. In the case of the apex outlet LVAD with centrifugal pump, blood flows from the left atrium through the left ventricle to the pump. Pump flow is regulated by preload, and preload is regulated by diastolic hemodynamics. The aim of this study is to analyze the relationship between pump flow and the diastolic hemodynamics of the native heart. Ten anesthetized intact pigs were studied after placement of an LVAD. Data were recorded with the LVAD off (control) and the LVAD on. The assist rate was changed to 25%, 50%, and 75%. The indexes of left ventricular (LV) diastolic function included LV myocardial relaxation (time constant of isovolumic pressure decay [Tau] and maximum negative dP/dt[LV dP/dt min]) and LV filling (peak filling rate [PFR], time to peak filling rate [tPFR], and diastolic filling time [DFT]). Stroke volume decreased significantly in 75% assist. LV end‐systolic pressure decreased significantly in 50% and 75% assist. LV end‐diastolic volume decreased as assist rate increased, but there were no significant changes. Stroke work decreased significantly in 50% and 75% assist. LV dP/dt min decreased significantly in 50% and 75% assist. Tau prolonged as assist rate increased, but there were no significant changes. DFT shortened significantly in 75% assist. PFR increased significantly in 75% assist. tPFR shortened significantly in 50% and 75% assist. In this study, LV relaxation delayed as an increasing of pump assist rate, but it suggested a result of reduction of cardiac work. Also, it was suggested that LVAD increases the pressure difference between the left atrium and the left ventricle in the diastolic phase. This phenomenon is due to the filling of the left ventricle. In this study it was suggested that as pump assist rate increases, it is more effective to keep cardiac function in the diastolic phase.
Pulsatile Ventricular Assist Device with Pericardial Inner Lining
Authors: Leirner Adolfo A. , Hayashida Sergio A. , Maizato Marina J.S. , Silva Maria de Lourdes L. , Cestari Idágene A. , Affeld Klaus
Published: March 2003

Abstract: Preserved pericardium in contact with blood is not thrombogenic, therefore avoiding the use of anticoagulants, and has excellent mechanical properties. Our objective is to take advantage of these characteristics and build a pulsatile ventricular assist device (VAD) with pericardium used as the inner lining of the blood chamber. A mold is used for the tanning of the pericardium, rendering it with an exact shape. A flexible polymeric structure is designed to serve as a base for the pericardium, guiding it and limiting its rate of strain. It consists of two halves, which when outfitted with the interior pericardium lining and connected to each other, form the blood chamber. This assembly is housed in rigid polyvinyl chloride (PVC) shells making up the air chamber for the pneumatic activation. Valves are likewise made of pericardium. Sealing of the chambers was tested statically up to 300 mm Hg with no air or fluid leakage. The device was tested for 60 continuous days in a mock loop, demonstrating hydrodynamic performance adequate for ventricular assist. Micrographs (confocal laser and scanning electron microscopy) were obtained of several pericardium areas, especially on the flexing regions that are a transition between the wet and dry regions. No sign of damage to the pericardium was observed either with the naked eye or at the microscopic level. From the hydraulic performance and materials viewpoints, a completely pericardium‐lined pulsatile VAD displaying a polymeric structure that avoids unpredictable bending and limits strain is feasible. The results warrant further studies regarding biocompatibility and strength advantages.
Ionic Dialysance Measurement Is Urea Distribution Volume Dependent: A New Approach to Better Results
Authors: Goldau Rainer , Kuhlmann Uwe , Samadi Nader , Gross Malte , Graf Thomas , Orlandini Giancarlo , Marcelli Daniele , Lange Harald
Published: March 2003

Abstract: Conductivity (CD)‐based dialysance measurements precisely match urea dialysance with <5% difference. For measurement, a CD step‐profile is applied by increasing dialysate inlet CD at time t0 for 10% above baseline and lasting for 2–5 min until t1, followed by a decrease to –4% until t2 and a final return to baseline, meanwhile recording dialysate CD at filter inlet (cdi) and outlet (cdo), dialysate flow (Qd), and ultrafiltration (UF)‐rate (Qf). Electrolytic dialysance (KeCn) is calculated by KeCnI,J = (1 −[cdoI−cdoJ]/[cdiI−cdiJ])(Qd+Qf) with time index I≠J. The combinations in I,J are not equivalent: KeCn0,1 < KeCn1,2 < KeCn0,2. Each difference is 2% to 5%, and a difference versus urea clearance remains. An in vivo on‐line clearance study (10 patients, 100 dialysis sessions, 265 measurements) with automatic electrolytical dialysance measurements and permanent data recording was conducted. Two methods were applied: a CD step‐profile and a significantly smaller, dynamic CD bolus. Both were compared to laboratory reference of urea clearance. Reference Kt/V has been calculated using equilibrated single‐pool methods and direct quantification. Urea generation was ignored. The results are as follows. The reference blood‐side urea clearance was 164.0 ± 11.8 ml/min, n = 265. The mean errors of the ionic dialysance results are KeCn0,1: −9.1 ± 4.8%, n = 250; KeCn1,2: −5.6 ± 4.4%, n = 250; KeCn0,2: 6.8 ± 7.7%, n = 250; KeCnBolus: 0.1 ± 4.8%, n = 162. The KeCnI,J error is urea distribution volume related. Kt/V comparison to equilibrated single pool is as follows: KeCn1,2t/V: 0.0 ± 5.0% (r = 0.96, n = 45); KeCnBolust/V: 5.3 ± 3.9% (r = 0.98, n = 44). The comparison to direct quantification is as follows: KeCn1,2t/V: −2 ± 6.4% (r = 0.95, n = 68); KeCnBolust/V: 3.2 ± 6.3% (r = 0.95, n = 66). V could roughly be measured. Dialysance measured by the step‐function method was dependent on sodium load and distribution volume while the CD‐bolus dialysance was not. Errors are generated by measurement‐induced sodium shift that is sufficient even to estimate urea distribution volume. For dialysance measurements, small dynamic CD boli are preferable to stable step functions.
The Microsystems Based Visual Prosthesis for Optic Nerve Stimulation
Authors: Delbeke Jean , Wanet‐Defalque M.C. , Gérard B. , Troosters M. , Michaux G. , Veraart C.
Published: March 2003

Abstract: The microsystems based visual prosthesis (MiViP) visual prosthesis generates visual perceptions well below safety and stimulator saturation limits. These perceptions, called phosphenes, are of reasonably small size and are broadly distributed in the visual field. They can thus be used to convey useful visual information. Psychophysical evaluations are being performed in order to assess the implantee's benefits in the use of the MiViP optic nerve visual prosthesis. In a pattern‐recognition task, the performance improved regularly with practice with an increasing score and a decreasing delay to recognition. These observations open the way toward an evaluation of general mobility improvement with the portable system. In conclusion, the results obtained so far still support the potential usefulness of the optic nerve visual prosthesis. A low‐resolution artificial vision can be expected from the prosthesis after extensive training.
Development of Muscular Blood Pumps Performed in a One‐Step Operation
Authors: Guldner Norbert W. , Klapproth Peter , Großherr Martin , Sievers Hans‐H.
Published: March 2003

Abstract: Up to now, the employment of skeletal muscle ventricles (SMVs) has required a two‐step operation, that is, first, the construction followed by a vascular delay and electrical conditioning, and second, the integration into circulation by a second operation. As shown previously, clenbuterol increased the power of electrically conditioned SMVs wrapped around a mock system. These clenbuterol‐supported SMVs pumped successfully from construction to several months against a pressure of 60–70 mm Hg. Due to these successful former experiments, a muscular blood pump has been employed via a one‐step procedure, trained within the circulation under the support of clenbuterol. It appeared to be hemodynamically relevant and is expected to become clinically practicable for the treatment of end‐stage heart failure.
Aortic Root Replacement Using Composite Valve Graft in Patients with Aortic Valve Disease and Aneurysm of the Ascending Aorta: Twenty Years' Experience of Late Results
Authors: Aomi Shigeyuki , Nakajima Masato , Nonoyama Masaki , Tomioka Hideyuki , Bonkohara Yukihiro , Satou Wataru , Kunii Yosihito , Endo Masahiro
Published: March 2003

Abstract: The purpose of this study was to evaluate the clinical outcome of composite valve graft replacement in 193 patients with aortic valve disease and aneurysm of the ascending aorta from January 1980 to June 1999. The clinical outcome was compared between the patients diagnosed with Marfan syndrome (M group) and those without Marfan syndrome (non‐M group), between those with aortic dissection (AD group) and without dissection (non‐AD group), between 2 different techniques for coronary artery reattchment (modified Bentall [mB] and modified Piehler [mP]), and between the time of operation (1980–1989 and 1990–1999). Long‐term outcome of this procedure was almost satisfactory with actuarial survival of 71.5 ± 4.4% at 10 years and freedom from reoperation of 76.5 ± 4.4% at 10 years. Freedom from cardiovascular events and freedom from reoperation were significantly lower in the M group and AD group than in the non‐M and non‐AD groups. Also, actuarial survival was significantly higher in the latter 10 years compared with the former 10 years. It was concluded that the improvement of perioperative management and proper selection of the technique for coronary artery reattachment could have improved the clinical outcome. In patients with Marfan syndrome or aortic dissection, there still remains a higher risk of cardiovascular event and future reoperation. Extensive aortic reconstruction or staged operation should be performed in such patients.
The Medtronic Intact Bioprosthesis: Clinical and Hemodynamic Performance Over 13 Years
Authors: De La Fuente Anselmo , Sánchez José Ramón , Fernández Juan Luis , Romero Javier , Berjon Jesús , Moriones Ignacio
Published: March 2003

Abstract: We evaluated our results over 13 years with the aortic‐position Medtronic Intact bioprosthesis. Our study involved 91 consecutive patients with isolated aortic valve replacement with the Medtronic Intact bioprosthesis. The follow‐up was complete for 95%. Mean follow‐up was 6.61 years (range 16 days–13 years), 590 patient years. Early mortality rate was 3.3%. Late mortality was 23 patients. Survival at 13 years was 53.52% (SD = 7.63%). The linearized rate of major thromboembolism was 0.34% per patient year; rate of major bleeding events was 0.33% per patient year. The rate of nonstructural dysfunction was 0.16% per patient year. Rate of reoperation was 0.53% and rate of structural valve deterioration was 0.16% per patient year. New York Heart Association (NYHA) postoperative classes were I to II in 92.21%. Gradients were as follows: 21 to 23.87 mm Hg, 23 to 18 mm Hg, 25 to 15.5 mm Hg, and 27 to 16.50 mm Hg. Structural valve deterioration was low during the 13 years of follow‐up. Valve gradients and areas remained the same over the follow‐up period. The Medtronic Intact bioprosthesis shows excellent clinical and hemodynamic performance at 13 years of follow up.
Protein Adsorption–Resistant Hollow Fibers for Blood Purification
Authors: Ishihara Kazuhiko , Hasegawa Takashi , Watanabe Junji , Iwasaki Yasuhiko
Published: March 2003

Abstract: Nonfouling polysulfone (PSf) hollow fiber membranes resistant to protein adsorption and deposition were newly developed by the addition of 2‐methacryloyloxyethyl phosphorylcholine (MPC) polymer. To improve hydrophilicity, permeability, and nonfouling characteristics of the PSf hollow fiber in a hemodialyzer, we synthesized a MPC polymer which can be blended with PSf for preparing the polymer alloy (PSf/MPC polymer). The composition of the MPC polymer blended in the PSf was in the range between 7.0 and 15 wt%. From the PSf/MPC polymer solution, flat membranes and hollow fibers could be prepared. These membranes took an asymmetric structure, and its mechanical strength was good. The surface characterization of the PSf/MPC polymer hollow fiber membrane by X‐ray photoelectron spectroscopy revealed that the MPC units were concentrated at the surface. The permeability for solutes through the PSf/MPC polymer membrane was higher, and the amount of protein adsorbed on the PSf/MPC polymer membrane was lower than those of the PSf membrane. Moreover, platelet adhesion was also effectively inhibited on the PSf/MPC polymer membrane.
Posttransplant Infections in the Tropical Countries
Authors: Jha Vivekanand , Chugh Kirpal S.
Published: March 2003

Abstract:Over half of all renal transplant recipients in the tropical countries develop a serious infection at some point in the posttransplant period and 20% to 40% of them succumb to these infections. Many of these infections are endemic to the region. A multitude of factors including unhygienic conditions, hot and humid climate, late presentation, lack of knowledge about the spectrum of organisms in these areas, scanty diagnostic techniques, and high cost of lifesaving antimicrobial agents contribute to this dismal outcome. Tuberculosis is observed in 10% to 15% of transplant recipients. Pleuropulmonary disease is most frequent, but the commonly employed tests are seldom helpful in the diagnosis. Bronchoalveolar lavage is very sensitive in early detection of this infection and allows timely institution of specific therapy. Hepatitis virus infections are generally acquired before transplant, and viral replication is accelerated under the effect of immunosuppressive therapy leading to chronic liver disease. Cytomegalovirus (CMV) disease has shown a fourfold increase after introduction of cyclosporine to the immunosuppressive regimes at our center. Coinfection with other bacteria or fungi is frequent in CMV‐infected allograft recipients. Opportunistic fungal infections are seen in less than 10% of allograft recipients, but this figure is likely an underestimate. The frequently encountered fungal infections includeCandida,Aspergillus,Cryptococcus, andMucor.Fungal infections carried a high mortality of over 65% at our center. The protean manifestations of the opportunistic infections and nonavailability of sensitive diagnostic tests in most centers in the underdeveloped countries often delay the diagnosis and institution of therapy.
Validation of the Coupling of Magnetic Resonance Imaging Velocity Measurements with Computational Fluid Dynamics in a U Bend
Authors: Glor F.P. , Westenberg J.J.M. , Vierendeels J. , Danilouchkine M. , Verdonck P.
Published: March 2003

Abstract: Magnetic resonance imaging (MRI) can be used in vivo in combination with computational fluid dynamics (CFD) to derive velocity profiles in space and time and accordingly, pressure drop and wall shear stress distribution in natural or artificial vessel segments. These hemodynamic data are difficult or impossible to acquire directly in vivo. Therefore, research has been performed combining MRI and CFD for flow simulations in flow phantoms, such as bends or anastomoses, and even in human vessels such as the aorta, the carotid, and the abdominal bifurcation. There is, however, no unanimity concerning the use of MRI velocity measurements as input for the inflow boundary condition of a CFD simulation. In this study, different input possibilities for the inflow boundary conditions are compared. MRI measurements of steady and pulsatile flow were performed on a U bend phantom, representing the aorta geometry. PAMFLOW (ESI Software, Krimpen aan den Ussel, The Netherlands), an industrial CFD software package, was used to solve the Navier‐Stokes equations for incompressible flow. Three main parameters were found to influence the choice of an inflow boundary condition type. First, the flow rate through a vessel should be exact, since it proves to be a determining factor for the accuracy of the velocity profile. The other decisive parameters are the physiology of the flow profile and the required computer processing unit time. Our comparative study indicates that the best way to handle an inflow boundary condition is to use the velocities measured by MRI at the inflow plane as being fixed velocities. However, before using these MRI velocity data, they first should be corrected for the partial volume effect by filtering and second scaled in order to obtain the correct flow rate. This implies that a reliable flow rate measurement absolutely is needed for CFD calculations based on MRI velocity measurements.
Ecosystem Health and Sustainable Communities: North and South
Authors: King Leslie A. , Hood Virginia L.
Published: March 2003

ABSTRACT It is at the local/community level that the connections among ecosystem health, the health of human communities, and individual livelihoods are most apparent and critical. This paper reports a number of community initiatives aimed at improving or providing alternative livelihoods, while at the same time conserving or restoring the integrity of the ecosystem on which the community depends. It presents case studies of Zimbabwe’s CAMPFIRE (Communal Areas Management Program for Indigenous Resources) and Akwesasne in northeastern North America, as well as examples from northern Canada, of communities that have attempted to integrate economic development, community values/culture, and the restoration of ecosystem and community health. In both the north and the south these communities face ecological pressures such as climate change, industrial pollution, loss of diversity and productivity, deforestation, and resulting loss of traditional livelihood strategies. They are also victims of global economic forces, economic and institutional globalization, and are struggling to make adaptive responses. Common themes are identified across the case studies and we identify the need for indicators and programs that recognize and reinforce the interconnections and guide development programs that integrate community and ecosystem health and sustainability.
Evolving Models of Human Health Toward an Ecosystem Context
Authors: VanLeeuwen J.A. , Waltner‐Toews D. , Abernathy T. , Smit B.
Published: March 2003

ABSTRACTCurrent models or frameworks used to represent and/or conduct research on determinants of human health have lagged behind in adopting emerging concepts of ecosystems: multiple spatial and temporal scales; nested hierarchies of socioeconomic and biophysical environments; inherent complexity of interrelationships among environmental components and influences; external environmental influences; and feedback loops between environments, providing self‐organizational capacity and functional emergent properties. This article provides a concise description of a number of human health models and their relevance to an ecosystem health context. A new model of human health is described, the “Butterfly Model of Health,” that draws on the strengths of previous health models, but more fully incorporates salient characteristics of ecosystems. In the new model, health is considered to be a societally defined, social, economic, and biological resource for self‐renewal and meeting goals. This capacity is dependent on an equitable balance between socioeconomic and biophysical environmental pressures. Within the model, the health of the individual or population (the body of the butterfly), enveloped by biological and behavioral filters, is affected by both biophysical and socioeconomic holarchic environments (the wings), which are influenced by each other through the actions of individuals. Health is present when the two wings of the butterfly are equitably balanced within and between their respective dimensions, with neither dominating and putting undo pressure on the other. The model is sufficiently flexible to conceptualize links with community and ecosystem models in a variety of contexts.
Using Energy Systems Theory To Define, Measure, and Interpret Ecological Integrity and Ecosystem Health
Authors: Campbell Daniel E.
Published: March 2003

ABSTRACT Energy systems theory provides a theoretical basis for defining, measuring, and interpreting the concepts of ecological integrity and ecosystem health. Ecological integrity is defined as an emergent property of ecosystems operating at maximum power that can be quantified using validated Energy Systems models. The cumulative empower production (emergy) calculated using these models is proposed as a measure of ecological integrity. Ecological integrity must be interpreted within the context of an ecosystem's position within the relevant hierarchies of organization and cycles of change that control system behavior. The local integrity and health of an ecosystem are normative concepts because they are evaluated relative to a standard or reference state. The underlying emergy signature responsible for generating ecosystem organization provides an expectation for this reference state. Ecosystems also have global integrity, which is manifested as the flexibility to maximize empower over time in the face of changing external forcing functions. Global integrity has no fixed reference but can be evaluated by comparing alternative system designs. Because the maximum empower principle is a general law that applies to all self‐organizing systems on all scales, these definitions for ecological integrity and ecosystem health apply to both natural ecosystems and ecosystems dominated by human activities. Human‐dominated ecosystems with the highest integrity will be those in which the sum of the empower produced by the economy and its supporting ecosystems is close to a maximum.
Rating the Sustainability of Nations
Authors: Zoeteman Kees
Published: March 2003

ABSTRACT Comparison of sustainability levels of societies has been difficult, as there is no framework that integrates its three main aspects: environment, economy, and social security. A concept is presented defining five levels of sustainability, characterized by growing awareness of and responsibility for the impacts of our actions in space and time. Examples of indicators comprising an Environmental Index, a Social Index, and an Economic Index are given and an overall sustainability index is tentatively calculated for 24 Nations. Differences in sustainability levels are shown, Sweden being the most and Sierra Leone the least sustainable nation.
The Economic Value of Forest Ecosystems
Authors: Pearce David W.
Published: March 2003

ABSTRACTForest ecosystems are being degraded and lost because of rapid population change and economic incentives that make forest conversion appear more profitable than forest conservation. All ecological functions of forests are also economic functions. Many important forest functions have no markets, and hence, no apparent economic value, justifying the use of forest land for other purposes. Imputing economic values to nonmarketed benefits has the potential to change radically the way we look at all forests and to make the pendulum swing back from a presumption in favor of forest conversion to more conservation and sustainable use. This paper surveys what we know about forest economic values and draws policy conclusions from the now substantial literature that values nonmarket benefits of forests. Estimating economic values is not enough. The subsequent stage of policy is to design markets that capture the values—‘market creation’—ideally for the benefit of the many vulnerable communities that rely on the forests for their well‐being. These conclusions support the wider argument for using effective economic instruments to promote conservation of the remaining forests. Forest loss involves: risks to human health; accelerated climate change; increased watershed disruption, adding to eutrophication in inland and coastal waters; loss of water quality; and loss of biodiversity.
Syntropic Ecotoxicology: A Heuristic Model for Understanding the Vulnerability of Ecological Systems to Stress
Authors: Downs Timothy J. , Ambrose Richard F.
Published: March 2003

ABSTRACT This paper argues for a syntropic, multilevel conceptualization of ecotoxicology beyond the simple organism‐level effects of poisons. Such a concept embraces complex systems, ecotoxicology, ecoepidemiology, and ecosystem health and integrity. One way of thinking about the relative stability of ecosystems and their biological and nonbiological components is the conditional (Bayesian) probability of their coherent versus incoherent response to perturbation. Anthropogenic and natural stress may change the structure, function and/or organization of dissipative systems at any level, compromising self‐regulation and making unstable incoherent responses more probable. Syntropic ecotoxicology argues for increased understanding of how ecotoxic agents or events may be disrupting self‐regulating mechanisms at the molecular, cellular, organismal, population, and/or community levels—their multilevel ecotoxicodynamics. In parallel, and adaptive to new knowledge, interdisciplinary teams of scientists, policy makers, and other stakeholders must collaborate effectively to mobilize and integrate financial, human, material, and information resources to prevent and control existing priority deterministic stressors.
Anthropogenic Calcium Depletion: A Unique Threat to Forest Ecosystem Health?
Authors: Schaberg Paul G. , DeHayes Donald H. , Hawley Gary J.
Published: March 2003

ABSTRACTNumerous anthropogenic factors can deplete calcium (Ca) from forest ecosystems. Because an adequate supply of Ca is needed to support fundamental biological functions, including cell membrane stability and stress response, the potential for Ca deficiency following the individual, cumulative, or potentially synergistic, influences of anthropogenic factors raises important questions concerning organism and ecosystem health. Past work has shown that one Ca‐depleting factor (foliar acid mist exposure) reduces concentrations of biologically important membrane‐associated Ca (mCa) from red spruce foliar cells, destabilizes these cells, and results in their increased susceptibility to the freezing injury responsible for red spruce decline in northeastern U.S. montane ecosystems. Data presented here indicate that these same disruptions can occur for other tree species and that soil‐based Ca manipulation can also alter critical mCa pools. Considering the unique role Ca plays in the physiological response of cells to environmental change and stress, we hypothesize that depletion of biologically available Ca (e.g., mCa) could result in a scenario similar to recognized immune deficiency syndromes in animals. A hypothetical pathway through which anthropogenically induced Ca deficiencies could predispose plants, and possibly animals, to exaggerated injury following exposure to environmental stress is presented, and the potential implications of this scenario to ecosystem health are discussed.
Analgesic Rebound Headache in Clinical Practice: Data From a Physician Survey
Authors: Rapoport Alan , Stang Paul , Gutterman Donna L. , Cady Roger , Markley Herbert , Weeks Randall , Saiers Jane , Fox Anthony W.
Published: March 2003

Background: Frequent, excessive use of over‐the‐counter or prescription analgesics may lead to analgesic rebound headache. Little is known about the magnitude of the health problem posed by analgesic rebound headache, its epidemiology, the characteristics of analgesic rebound headache sufferers, or about physicians’ approaches to treatment.

Methods: Four hundred seventy‐three practitioners, who had previously expressed an interest in the treatment of headache, were mailed a questionnaire designed to capture information about the frequency and management of analgesic rebound headache and about the characteristics of analgesic rebound headache sufferers.

Results: Completed questionnaires were returned by 174 practitioners (37%) from 40 states, the District of Columbia, and Puerto Rico. More than 40% of respondents indicated that analgesic rebound headache was present in at least 20% of their patients. On average, the physicians reported that 73% of patients with analgesic rebound headache were women. Analgesic rebound headache was most likely to occur in patients aged 31 to 40 years. No one analgesic was consistently identified as causative, although acetaminophen, butalbital + aspirin + caffeine, and aspirin were commonly used by patients. Eighty percent of respondents indicated that depression was commonly observed in analgesic rebound headache sufferers; 77% indicated that physical conditions (especially gastrointestinal symptoms) were commonly observed. A variety of therapeutic strategies, including pharmacotherapy, were used in the management of analgesic rebound headache.

Conclusion: Analgesic rebound headache was recognized as a distinct entity and a substantive component in more than 40% of the practices of 174 surveyed practitioners. Genera practitioners, who see a wide variety of patient types with a spectrum of complaints, need to be able to diagnose analgesic rebound headache by taking a good history.
Cerebrovascular Reactivity in Migraine With and Without Aura
Authors: Silvestrini Mauro , Matteis Maria , Troisi Elio , Cupini Letizia M. , Bernardi Giorgio
Published: March 2003

Abnormal cerebrovascular regulation has been implicated in the pathogenesis of migraine. Our aim in this study was to evaluate cerebrovascular reactivity to different stimulations in migraine with and without aura. Using bilateral transcranial Doppler, the changes of flow velocity during hypercapnia and mental and motor activity were measured in the middle cerebral adages of 15 controls and 30 patients with migraine with aura (n=l5) or without aura (n=15) in an attack‐free period. Vascular response to all tests was similar in controls and patients. In patients with unilateral headache, no side‐to‐side difference was found. These findings suggest that no alteration of cerebrovascular reactivity exists outside attacks in migraine with and without aura. Further studies with transcranial Doppler considering all intracranial vessels and the comparison with other techniques of flow investigation with better regional resolution are needed to confirm these data.