bluuebunny/crossref_metadata_2025 huggingface dataset:
Electromyogram‐Controlled Functional Electrical Stimulation for Treatment of the Paralyzed Upper Extremity
Authors: Rakoš Monika , Freudenschuβ Barbara , Girsch Werner , Hofer Christian , Kaus Jürgen , Meiners Thomas , Paternostro Tatjana , Mayr Winfried
Published: March 2003

Spinal cord lesions at level C5 to C6 lead to loss of hand functions and lesions at C4 to additional deficits of arm functionality. The presented dual channel surface stimulator with dual channel electromyogram (EMG) measurement was developed to investigate control strategies for an EMG‐controlled implantable stimulation system and serves in addition as a therapy device for patients with partial innervation but weak muscle force. Four different control strategies for stimulation amplitude are available. The amplitude can be preset manually or can follow the preprocessed EMG signals proportionally. The shoulder control program allows proportional control of both stimulation channels with one EMG channel while the second EMG channel serves as the channel selector. Finally, a special feedback training program triggers a stimulation burst when EMG activity is detected. During a 2 year patient study, 18 patients from 2 hospitals and 1 rehabilitation center performed the feedback training. Almost all patients obtained an improvement of functionality. Apart from muscle strengthening, the feedback effect led to an improvement of proprioception and supported relearning of motions. For the documentation of the training status, functional muscle test (British Medical Research Council) and measurements of power, angle, torque, muscle fatigue, and EMG were performed. Obviously, EMG triggered stimulation provides several advantages compared to conventional passive electrical stimulation.
Cytokine and Endothelial Damage in Pulsatile and Nonpulsatile Cardiopulmonary Bypass
Authors: Orime Yukihiko , Shiono Motomi , Hata Hiroaki , Yagi Shinya , Tsukamoto Saeki , Okumura Haruhiko , Nakata Kin‐ichi , Kimura Shun‐ichi , Hata Mitsumasa , Sezai Akira , Sezai Yukiyasu
Published: March 2003

Recently, several types of centrifugal pumps have been widely used as the main pumps for cardiopulmonary bypass (CPB). However, according to the results of our experimental studies, after cardiogenic shock, pulsatile flow was effective in maintaining the functions and microcirculations of end organs, especially those of the liver and kidney. To estimate the effectiveness of pulsatility during CPB, cytokine and endothelin and other metabolic parameters were measured in clinical pulsatile and nonpulsatile CPB cases. From March to May 1997, CPB was performed in 18 elective cases (14 ischemic and 4 valvular disease). In 9 cases, pulsatile perfusion was achieved by the Jostra HL20, which is a newly developed CPB pump (Group P). A nonpulsatile centrifugal pump was used in 9 patients (Group NP). In both groups, as chemical and metabolic mediators, interleukin‐8 (IL‐8), endothelin‐1 (ET‐1), and plasma free hemoglobin were measured before and during CPB, and 0.5, 3, 6, 9, 18 h after weaning from CPB. This pulsatile CPB pump could be very simply and easily controlled and could easily produce pulsatile flow. There were no significant differences in CPB time (CPBT), aortic cross clamp time (ACCT), mean aortic pressure, or pump flow during CPB between the both groups. The ET‐1 level of Group P was significantly (p < 0.05) lower than that of Group NP 9 h after CPB weaning. The IL‐8 level of Group P also showed a lower value than that of Group NP. As for plasma free hemoglobin, there were no significant differences between the groups. These results suggested that even in conventional CPB, pulsatility was effective to reduce endothelial damage and suppress cytokine activation. It may play a important role in maintaining the functions and microcirculations of end organs during CPB.
A New Control Method That Estimates the Backflow in a Centrifugal Pump
Authors: Nakata  , Ohtsuka  , Yoshikawa  , Takano  , Glueck  , Fujisawa  , Makinouchi  , Yokokawa  , Nosé
Published: March 2003

The rotary blood pump will be widely used in the near future as an implantable left ventricular assist device (LVAD). However, one obstacle for the centrifugal pump is a control method that can maintain an optimum flow rate in a physiological condition. Thus, the object of this study is to develop this optimum control system for the centrifugal pump. If the heart function and pump efficiency are stable, the ratio of the systole current to the the diastole current (S/D) will be a fixed value. However, if the heart function and pump efficiency are unstable, S/D will not be a fixed value. This control system was investigated with a calf that was subjected to an ex vivo LVAD study. The LVAD was a Gyro C1E3 centrifugal pump. The pump flow rate was changed to 1.5, 3.5, 5.2, and 6.2 L/min. According to the changes of the pump flow rates, the S/D values were 1.01 ± 0.01, 1.06 ± 0.05, 1.03 ± 0.01, and 1.03 ± 0.01, respectively. There was no statistical difference among the 3 groups. In a separate experiment, the backflow condition S/D was 1.88 ± 0.6, and the normal condition S/D was 1.35 ± 0.5. There was a statistical difference between the 2 groups. The results of this study suggest that S/D is not influenced by the pump flow rate. However, the S/D was changed when the pump was in a backflow condition. This method will be useful in controlling a centrifugal pump requiring only electrical current information.
Pediatric Cardiac Extracorporeal Membrane Oxygenation in Congenital Heart Disease: The Cardiologist's View
Authors: Salzer‐Muhar Ulrike E. , Marx Manfred , Wimmer Maria
Published: March 2003

Abstract: There is no doubt that extracorporeal membrane oxygenation (ECMO) as a powerful therapeutic modality in critically ill newborn infants and older children with congenital heart disease has implications for the pediatric cardiologist. His responsibilities as consultant in the intensive care unit include screening for unsuspected cyanotic heart disease in neonatal candidates referred for ECMO and appraisal of surgical repair in postcardiotomy patients as well as assessment of postoperative hemodynamics and detection of complications during perfusion. A close cooperation between intensive care specialists and other appropriate specialists (pediatric cardiologists, cardiac surgeons, and anesthesiologists) is required for the process of decision making prior to initiation of postoperative ECMO in the individual patient with congenital heart disease. Long‐term survival, morbidity, cerebrovascular complications, and neurodevelopmental sequelae of these near miss children remain a critical issue. Furthermore, there is a strong need for professional psychosocial support of affected parents, both in the hospital and after discharge.
Comparative Study of Bioartificial Liver Support and Plasma Exchange for Treatment of Pigs with Fulminant Hepatic Failure
Authors: Kamohara Yukio , Fujioka Hikaru , Eguchi Susumu , Kawashita Yujo , Furui Junichiro , Kanematsu Takashi
Published: March 2003

Abstract: Recently, bioartificial liver (BAL) treatment was reported to provide beneficial effects for patients with fulminant hepatic failure (FHF). Some success in experimental or clinical trials has been reported; however, the evaluation of BAL efficacy remains unclear, especially in comparison with other treatments for FHF. The purpose of this study was to compare the efficacy between BAL and plasma exchange (PE) in experimentally induced FHF in pigs. Pigs undergoing hepatic devascularization (HD) were placed into the following groups: no treatment (control; n = 6), BAL treatment (BAL; n = 5), and plasma exchange (PE; n = 5). Each treatment was initiated 6 h after HD and lasted for 4 h. BAL treatment significantly improved liver functions in FHF pigs. The decrease in cerebral perfusion pressure was also significantly suppressed in the pigs with BAL, and their survival time was prolonged compared with the results in pigs with PE. The effects of BAL outperform those of PE in the treatment of experimental FHF model.
Fiber Reinforced Calcium Phosphate Cement
Authors: Dos Santos Luís Alberto , De Oliveira Luci Cristina , Da Silva Rigo Eliana Cristina , Carrodéguas Raúl Garcia , Boschi Anselmo Ortega , Fonseca de Arruda Antônio Celso
Published: March 2003

Abstract: The term calcium phosphate cement was introduced by Gruninger et al.
(1). This type of cement can be prepared by reacting a calcium phosphate salt with an aqueous solution, which causes it to set by the crossing of the precipitated crystals. These cements offer a series of advantages that allow their use as grafts and substitutes of damaged parts of the bone system. However, these cements have low mechanical strength compared to human bones. This work studied the influence of the use of polyamide fibers in the mechanical properties of a calcium phosphate cement based on α‐tricalcium phosphate as well as the mechanisms involved in the increase of mechanical strength. The results demonstrate the feasibility of the use of polymeric fibers to increase mechanical strength and the need for coupling agents for the effective performance of the fibers as reinforcement in these materials.
Effect of Heparin, Platelets, Activated Platelets, Platelet Fragments, and Hematocrit on Activated Clotting Time
Authors: Girardi L. , Sudi K. , Muntean W.
Published: March 2003

Abstract: Activated clotting time (ACT) is the most commonly used laboratory test to control the heparin effect during extracorporeal techniques. The study was undertaken in order to test in vitro the influence of heparin, platelet count, hematocrit, platelet fragmentation, and platelet activation on ACT. Blood was drawn from volunteer donors into syringes containing citrate. Platelet counts and hematocrit were modified. Platelets were fragmented by sonifier or activated by collagen and adenosine diphosphate (ADP). Different heparin final concentrations were created. Increasing concentrations of heparin had a significant effect on ACT. However, it was not predictable in every case in concentrations lower than 1.0 U/ml. Platelet count generally had no significant effect on ACT. The effect of hematocrit was detectable in a group but not in single cases. Fragmented platelets significantly shortened ACT only without addition of heparin, and the effect was only partly predictable. Activation of platelets by collagen and ADP induced no significant changes. Our results show that heparin is reflected by ACT but that effect is not predictable in every specific patient. Our results also show that other variables that may be altered during extracorporeal techniques such as platelet count, hematocrit, activation, and fragmentation of platelets do not severely influence the ACT.
Sensorless Flow and Head Estimation in the VentrAssist Rotary Blood Pump
Authors: Ayre P.J. , Vidakovic S.S. , Tansley G.D. , Watterson P.A. , Lovell N.H.
Published: March 2003

Abstract: Flow rate and pressure difference (or head) are key variables needed in the control of implantable rotary blood pumps. However, use of flow and/or pressure probes can decrease reliability and increase system power consumption and expense. For a given fluid viscosity, the flow state is determined by any 2 of the 4 pump variables: Flow, pressure difference, speed, and motor input power can be used. Thus, if viscosity is known or if its influence is sufficiently small, flow rate and pressure difference can be estimated from the motor speed and motor input power. For the VentrAssist centrifugal blood pump, which uses a hydrodynamic bearing, sensorless flow and pressure head estimation accuracy of 2 of our impeller designs were compared for a viscosity range of 1.2 to 4.5 mPas. This showed impeller design optimization can improve estimation accuracy. We also compared estimation accuracy using 2 blood analogues used in vitro, aqueous glycerol and red blood cells suspended in Haemaccel. The nature of the blood analogue and not only the viscosity of the fluid seems to influence estimation accuracy in our pump.
Vacuum Assisted Cardiopulmonary Bypass in Minimally Invasive Cardiac Surgery: Its Feasibility and Effects on Hemolysis
Authors: Shin Hankei , Yozu Ryohei , Maehara Tadaaki , Matayoshi Toru , Morita Masanori , Kawai Yoko , Yamada Tatsuya , Kawada Shiaki
Published: March 2003

Abstract: The present study describes a cardiopulmonary bypass (CPB) technique that incorporates vacuum assisted venous drainage and arterial return using a centrifugal pump in minimally invasive cardiac surgery (MICS). The technique was performed on 40 patients scheduled to undergo MICS. The proposed CPB technique enables a good operative field to be obtained even through a limited incision through the use of peripheral cannulation using small cannulae. Vacuum pressure was applied to the venous reservoir (−43 ± 14 mm Hg) to maintain adequate CPB flow (>2.4 L × min−1× M−2). The effects of CPB on hemolysis were subsequently compared between patients who underwent the proposed procedure (MICS group; n = 6) and a control group who underwent coronary arterial bypass grafting (CABG group; n = 6) with conventional CPB. Plasma free hemoglobin (FHb) increased and plasma haptoglobin (Hp) decreased during CPB in both groups, with no significant difference between the groups. By the next day, FHb had returned to pre‐CPB levels whereas Hp remained lower in both groups. Again, these values did not differ significantly between groups. Thus, we conclude that the proposed CPB technique is useful in MICS with acceptable effects on hemolysis.
Strategy of Circulatory Support with Percutaneous Cardiopulmonary Support
Authors: Hata Mitsumasa , Shiono Motomi , Orime Yukihiko , Yagi Shin‐ya , Yamamoto Tomonori , Okumura Haruhiko , Kimura Shun‐ichi , Nakata Kin‐ichi , Kashiwazaki Satoshi , Choh Shinsuke , Negishi Nanao , Sezai Yukiyasu
Published: March 2003

Abstract: We evaluated the efficacy and problems of circulatory support with percutaneous cardiopulmonary support (PCPS) for severe cardiogenic shock and discussed our strategy of mechanical circulatory assist for severe cardiopulmonary failure. We also described the effects of an alternative way of PCPS as venoarterial (VA) bypass from the right atrium (RA) to the ascending aorta (Ao), which was used recently in 3 patients. Over the past 9 years, 30 patients (20 men and 10 women; mean age: 61 years) received perioperative PCPS at our institution. Indications of PCPS were cardiopulmonary bypass weaning in 13 patients, postoperative low output syndrome (LOS) in 14 patients, and preoperative cardiogenic shock in 3 patients. Approaches of the PCPS system were the femoral artery to the femoral vein (F‐F) in 21 patients, the RA to the femoral artery (RA‐FA) in 5 patients, the RA to the Ao (RA‐Ao) in 3 patients, and the right and left atrium to the Ao in 1 patient. Seventeen (56.7%) patients were weaned from mechanical circulatory support (Group 1) and the remaining 13 patients were not (Group 2). In Group 1, PCPS running time was 33.1 ± 13.6 h, which was significantly shorter than that of Group 2 (70.6 ± 44.4 h). Left ventricular ejection fraction was improved from 34.8 ± 12.0% at the pump to 42.5 ± 4.6% after 24 h support in Group 1, which was significantly better than that of Group 2 (21.6 ± 3.5%). In particular, it was 48.6 ± 5.7% in the patients with RA‐Ao, which was further improved. Two of 3 patients with RA‐Ao were discharged. Thrombectomy was carried out for ischemic complication of the lower extremity in 5 patients with F‐F and 1 patient with RA‐FA. One patient with F‐F needed amputation of the leg due to necrosis. Thirteen patients (43.3%) were discharged. Hospital mortality indicated 17 patients (56.7%). Fifteen patients died with multiple organ failure. In conclusion, our alternate strategy of assisted circulation for severe cardiac failure is as follows. In patients with postcardiotomy cardiogenic shock or LOS, PCPS should be applied first under intraaortic balloon pumping (IABP) assist for a maximum of 2 or 3 days. In older aged patients particularly, the RA‐Ao approach of PCPS is superior to control flow rate easily, with less of the left ventricular afterload and ischemic complications of the lower extremity. If native cardiac function does not recover and longer support is necessary, several types of ventricular assist devices should be introduced, according to end‐organ function and the expected support period.
Tissue Engineering Research in Oral Implant Surgery
Authors: Ueda Minoru , Tohnai Iwai , Nakai Hidetaka
Published: March 2003

Abstract: In this article, we introduce some of the more extensively evaluated technologies using concepts of tissue engineering. We report on hard tissue engineering and soft tissue engineering and their utility for dental implant therapy. For hard tissue engineering, we evaluated human recombinant bone morphogenetic protein‐2 and marrow mesenchymal stem cells using a model of sinus augmentation procedure in rabbit. We also describe distraction osteogenesis as another category for hard tissue engineering. In addition, we evaluate soft tissue management using cultured epithelial grafting for soft tissue engineering. The results of our tissue regeneration materials and methods in this study are positive. When the tissue engineering materials are used in clinics in the future, implant surgery could be the leading field.
Evaluation of Water and Electrolyte Transport of Tubular Epithelial Cells Under Osmotic and Hydraulic Pressure for Development of Bioartificial Tubules
Authors: Terashima Masuo , Fujita Yuji , Sugano Katsuhiro , Asano Manabu , Kagiwada Naoko , Sheng Y , Nakamura Shingo , Hasegawa Azusa , Kakuta Takatoshi , Saito Akira
Published: March 2003

Abstract: Our aim was to develop bioartificial tubules using tubular epithelial cells and artificial membranes and evaluate the function of water and electrolyte transport by various tubular epithelial cells. The cells were cultivated onto extracellular matrix (ProNectin F) coating polycarbonate membrane. Water transport from the apical to the basolateral site of cells was examined using a modified Ussing chamber module. Water transport under colloidal osmotic pressure on the apical site and hydraulic pressure on the basolateral site were higher in JTC‐12, LLC‐PK1 cells than in MDCK cells. Water transport under osmotic plus hydraulic pressure was highest in LLC‐PK1 cells. We made bioartificial tubules using LLC‐PK1 cells and polysulfone hollow fiber cartridges. Water and Na ion transport function was high, and BUN and creatinine passage was recognized in these bioartificial tubules. BUN and creatinine concentrations of reabsorption fluid in these bioartificial tubules were significantly lower than those concentrations of control media and of noncell attached polysulfone hollow fiber cartridges. Though LLC‐PK1 cells were more preferable cells for the use of bioartificial tubules in terms of water and electrolyte transport, the passage of BUN and creatinine was not appropriate for clinical use. To select more preferable cells for bioartificial tubules which transport water and electrolytes and do not induce passage of uremic toxins is necessary.
Comparative Analysis of Human Serum Albumin Adsorption and Complement Activation for Intraocular Lenses
Authors: Pokidysheva Elena N. , Maklakova Irina A. , Belomestnaya Zinaida M. , Perova Nadejda V. , Bagrov Sergey N. , Sevastianov Viktor I.
Published: March 2003

Abstract: Intraocular liquid, in contrast to blood, has no cellular components; therefore, proteins (human serum albumin [HSA], and [α, β, γ] globulins) are the major components that determine patients' response to the intraocular lens (IOL) surface. In addition to the amount of adsorbed proteins, the possibility of its conformational changes, including conformational changes of globulins C1 and C3 that respond for the activation of the complements system by the classical and alternative pathways, cannot be excluded. The interaction between IOLs and protein components of intraocular liquid directly influences the ocular exudative reaction in the early postoperational period, the intensity of cellular and pigmental scurf on the surface of the IOLs, and the state of endothelial cells of the cornea in the distant postoperational period. Our goal was to compare the interaction of commercial IOLs made from polymethylmethacrylate, silicone, poly‐2‐hydroxyethyl methacrylate (p‐HEMA), and copolymer p‐HEMA with collagen with HSA and the complement system. The total internal reflection fluorescence (TIRF) method and hemolytic assay were used for this task, respectively. It has been demonstrated that the probability of biocompatibility of commercially produced IOLs on the stage of protein adsorption can be evaluated using the kinetic of HSA‐fluorescein isothiocyanate adsorption onto the IOL surface by the TIRF method. In the case of IOLs from p‐HEMA, a negative correlation was shown between the degree of irreversible adsorption of HSA and the minimum relative rate constant of the surface‐induced complement activation. We did not find any correlation between hydrophilicity/hydrophobicity of lenses and their adsorptional properties including complement activation. From suggested adsorptional criteria in vitro for biocompatible surfaces, the hydrogel lens from p‐HEMA has a lower probability of biocompatibility in comparison with other IOLs.
Are Standard Human Coagulation Tests Suitable in Pigs and Calves During Extracorporeal Circulation?
Authors: Mueller Xavier M. , Tevaearai Hendrick T. , Jegger David , Tucker Om , Von Segesser Ludwig K.
Published: March 2003

Abstract: The thrombogenicity of membrane oxygenators as well as clotting parameters profiles, using standard human clotting tests, was analyzed in calves and pigs during 6 h perfusion. Three calves and 3 pigs were connected to extracorporeal circulation with standard heparinization. Blood samples were taken for coagulation variables throughout perfusion, and oxygenators were examined for clot deposits at the end of the experiment. Two out of 3 oxygenators of the calf group presented clot deposits while none in the pig group did. Baseline coagulation variables of pigs showed values similar to those of humans while neither extrinsic nor intrinsic pathways could be activated in calves with standard human coagulation tests. The calf model, in conclusion, was confirmed to be a difficult model for the testing of extracorporeal circulation device resistance to thrombus formation, which is, however, not reflected by standard human coagulation tests. The pig model is a better model in which both coagulation pathways could be activated with standard human coagulation tests.
A Hybrid Compliant Vascular Graft Seeded with Microvascular Endothelial Cells Extracted from Human Omentum
Authors: Salacinski Henryk J. , Punshon Geoffrey , Krijgsman Brandon , Hamilton George , Seifalian Alexander M.
Published: March 2003

Abstract: We report the development of a hybrid vascular graft using an innovative compliant poly(carbonate‐urea)urethane unlike any previous polyurethane MyoLink as a permanent scaffold. The engineered graft has a hierarchical arterial structure: a monolayer of oriented microvascular endothelial cells (MVECs) and 3‐D matrix (human collagen Type 4/dermatan sulfate) bonded onto MyoLink. The grafts' clinical feasibility was evaluated by determining optimal MVEC seeding density, incubation time, viability, and adhesion of these cells when exposed to arterial shear stress. MVECs from human omentum were isolated by a new centrifugation protocol, radiolabeled and seeded onto hybrid graft 2 to 18 × 105 cells/cm2 for 24 h at 37°C and for 1 to 5 h at 6 × 105 cells/cm2, washed 3 times, and gamma counted. Qualitative assessment of seeding density/incubation was also undertaken with scanning electron microscopy (SEM) and viability tested with a modified Alamar Blue assay. A pulsatile flow phantom was used to subject the hybrid graft (200 mm length, 5 mm internal diameter) seeded with radiolabeled MVECs (6 × 105 cells/cm2 at 2 h) to arterial shear and dynamic scintigraphy images acquired in real time using a nuclear medicine gamma camera system during 14 h of perfusion (n = 6). The optimal seeding density was 6 × 105 cells/cm2, and qualitative SEM confirmed this. Incubating cells for 2 h produced significantly greater cell attachment than was seen for 1 h incubation (p < 0.05), and there was no significant difference in adhesion between cells incubated over the 2 h. Exposure of grafts to acute shear stress resulted in significantly higher proportions of initial cells attached to hybrid grafts compared to native MyoLink grafts (67 ± 3% versus 55 ± 2%, p < 0.001). As shown here, tissue engineering of native Myolink grafts significantly reduces the seeding density and incubation time to produce a monolayer onto which cells adhere to better.
Low‐Flux Versus High‐Flux Synthetic Dialysis Membrane in Acute Renal Failure: Prospective Randomized Study
Authors: Ponikvar Jadranka Buturović , Rus Rina R. , Kenda Rajko B. , Bren Andrej F. , Ponikvar Rafael R.
Published: March 2003

Abstract: The influence of dialyzer membrane on the morbidity and mortality of patients with acute renal failure remains a matter of debate. The aim of the prospective randomized clinical study was to assess the influence of the flux of a synthetic dialyzer membrane on patients' survival rate, restitution of renal function, and duration of hemodialysis treatment of patients with acute renal failure as a part of multiorgan failure. Seventy‐two patients treated in intensive care units of the University Medical Center Ljubljana were randomized according to the dialyzer used throughout the duration of hemodialysis treatment. There were 38 patients in the low‐flux group (dialyzer F6, low‐flux polysuphone, Fresenius, Bad Homburg, Germany) and 34 patients in the high‐flux group (dialyzer Filtral 12, sulphonated high‐flux polyacrylonitrile, Hospal, Industrie Meyzieu, France). Both groups were balanced in terms of sex, age, APACHE II score, oliguria before dialysis, cause of acute renal failure, innotropic support, mechanical ventilation, and the number of failing organs. The patients' survival rate was 18.7% in the low‐flux group and 20.6% in the high‐flux group. Ten patients (26.3%) recovered their renal function in the low‐flux group and 8 (23.5%) in the high‐flux group. Hemodialysis treatment lasted 11.2 days in the low‐flux and 10.7 days in the high‐flux group. An analysis of subgroups with a lower mortality rate (subgroup of patients without oliguria and subgroup of patients with less than 4 failed organ systems) did not show significant differences between the low‐flux and high‐flux groups in terms of survival rate, recovery of renal function, and duration of hemodialysis treatment. In conclusion, no significant differences were found in the results of low‐flux versus high‐flux synthetic membrane dialyzer treatment in patients with acute renal failure as a part of multiorgan failure in terms of survival rate, recovery of renal function, incidence of oliguria during hemodialysis, and duration of hemodialysis treatment. The number of failing organs seems to be the most important single factor determining the survival of patients with acute renal failure as a part of multiorgan failure.
Pyrogen Retention by Highly Permeable Synthetic Membranes During In Vitro Dialysis
Authors: Lonnemann Gerhard , Sereni Luisa , Lemke Horst‐Dieter , Tetta Ciro
Published: March 2003

Abstract: Pyrogen permeability of the new highly permeable synthetic membrane polyethersulfone (DIAPES) was compared to polysulfone in vitro dialysis experiments with heparinized human donor blood in the blood compartment. After sterile dialysis for 5 min, dialysate was contaminated with a culture filtrate of Pseudomonas aeruginosa using high and moderate challenge doses (Limulus assay reactivity 20,000 EU/ml and 50 EU/ml, respectively). Whole blood samples were separated from the blood compartment during the sterile (5 min) and contaminated (60 min) phases of dialysis and incubated for 6 h at 37°C. Blood samples were lysed, and interleukin‐1β and tumor necrosis factor α were measured by specific ELISAs. Moderate dialysate contamination (50 EU/ml) did not induce detectable cytokine production in whole blood. High challenge dose (20,000 EU/ml) induced whole blood interleukin‐1β and tumor necrosis factor α production in the blood compartment, which was higher with DIAPES than with polysulfone after 30 min. After 60 min, membrane‐dependent differences were no longer detectable. Pyrogen concentrations in the dialysate decreased with time indicating adsorption of cytokine‐inducing substances to the dialyzer membrane. Pyrogens adsorbed to dialyzer membranes were resuspended during recirculation of sterile phosphate‐buffered saline in the dialysate compartment and retained cytokine‐inducing activity as seen from whole blood incubation experiments. DIAPES and polysulfone adsorbed pyrogens in the presence of whole blood. Pyrogen adsorption to the membrane polymer and/or to the protein coat on the membrane prevented the passage of pyrogens in the presence of moderately contaminated dialysate. High grade dialysate contamination caused breakthrough of pyrogens into the blood with DIAPES and polysulfone. In order to reduce the risk of a dialysis‐dependent inflammatory response, dialysate of high bacteriological quality (ultrapure dialysate) should be mandatory.
The Index of Motor Current Amplitude Has Feasibility in Control for Continuous Flow Pumps and Evaluation of Left Ventricular Function
Authors: Endo George , Araki Kenji , Kojima Kazushi , Nakamura Kunihide , Matsuzaki Yasunori , Onitsuka Toshio
Published: March 2003

Abstract:The index of motor current amplitude (ICA) has feasibility in continuous‐flow ventricular assist device control. It can demonstrate the safe range of pump speed, which exists between the starting point of total assistance (t‐point) and the starting point of sucking (s‐point). The objective of this study was to investigate how the ICA characteristic curve changes with each condition of contractility, preload, and afterload changes. We changed preload, afterload, and contractility of closed‐mock circulation and plotted the change of the ICA value against pump speed. Then the shift of ICA characteristic curve against the change of each condition was considered. When preload increased, ICA characteristic curves showed the expansion of a safe range. When afterload increased, ICA characteristic curves were shifted to the high rotation side, slightly narrowing a safe range. When contractility increased, ICA characteristic curves showed the shift of a convex above to narrowing of a safe range. As these shift patterns were observed even when the driving conditions of a circuit changed, reproducibility was checked. Understanding the feature of a shift pattern of ICA characteristic curves correctly, a possibility that change of the heart function could be predicted by change of ICA value and a possibility for a flexible control method based on ICA, according to hemodynamic state, were suggested.
Simulation of the BP‐80 Blood Pump
Authors: Watanabe Nobuo , Karsak Oezcan , Neudel Frank , Kink Thomas , Apel Joern , Fujimoto Tetsuo , Reul Helmut , Takatani Setsuo
Published: March 2003

Abstract: In this study, computational fluid dynamics (CFD) analysis was applied to investigate the flow within a commercially available Biopump, BP‐80 (Medtronic, Minneapolis, MN, U.S.A.). The Biopump was selected because, for this purpose, a great number of experimental hemolysis data is available. The process of geometry representation and grid generation was focused on, due to its high impact on the numerical results. This process incorporated the use of three commercially available software packages for three‐dimensional computer‐aided design (3D‐CAD), grid generation, and solving, respectively. For the purpose of validation, the head/flow characteristics of the pump were experimentally obtained and compared to the computed data. The results showed a rough agreement between CFD data and experimental data. Further investigations should cover detailed shear stress analyses and computation of other hemolysis‐related quantities.
Flow Dynamic Comparison of Peripheral Venous Cannulas Used with Centrifugal Pump Assistance In Vitro
Authors: Jegger David , Tevaearai Hendrik T. , Mueller Xavier M. , Pierrel Nicolas , Horisberger Judith , Von Segesser Ludwig K.
Published: March 2003

Abstract: Because of the risk of vein collapse, the benefits of using a centrifugal pump to assist venous drainage for cardiopulmonary bypass are limited when the tips of peripheral cannulas are maintained within the vena cava. Using a mock circuit including 20 mm diameter latex tubing to mimic a vena cava, we compared the performance of 6 commercially available peripheral venous cannulas and attempted to determine potential factors influencing maximal flow drainage before vein collapse. A close correlation was observed with the total hole area of the cannula. Best performance (5.10 ± 0.08 L/min) was obtained with an 8 mm internal diameter (ID) cannula and 343 mm2 total hole area. A larger cannula (ID 9.2 mm) with only 209 mm2 total hole area drained 5.03 ± 0.05 L/min whereas a smaller cannula (ID 6.7 mm) with a total hole area of 586 mm2 also allowed a similar flow of 5.03 ± 0.12 L/min. Therefore, the total hole area appears to be a critical factor in designing peripheral cannulas used in restricted chambers such as vena cavae.
Evaluation of Cellular Affinity and Compatibility to Biodegradable Polyesters and Type‐II Collagen‐Modified Scaffolds Using Immortalized Rat Chondrocytes
Authors: Hsu Shan‐hui , Tsai Ching‐Lin , Tang Cheng‐Ming
Published: March 2003

Abstract: Immortalized rat chondrocytes (IRCs) were employed to evaluate the cytocompatibility of different biodegradable polyester scaffolds for chondrocyte seeding and cartilage tissue engineering in vitro due to the limitation of using freshly harvested chondroctyes. Cells were seeded onto the films and the porous substrates as well as into the three‐dimensional scaffolds made of the biodegradable polyesters including poly(l‐lactide) (PLLA) and two poly(lactide‐co‐glycolide)s (PLGAs). The materials were characterized by water contact angle, electron spectroscopy for chemical analysis (ESCA), and microscopy. PLGA50/50, one of the PLGAs, had the largest cell numbers at 24 h and 96 h (close to the tissue culture polystyrene control), possibly due to its lower contact angle, higher oxygen/carbon (O/C) atomic ratio, and larger degradation rate. When the surface was further modified by cross‐linked Type‐II collagen, cell population was significantly enhanced (two‐ to fourfold). The adhesion and proliferation behavior of IRCs on different materials was parallel to that of rabbit chondrocytes, but was more reproducible in general. IRCs are thus suitable for evaluation of different polymer scaffolds. Despite the favorable cytocompatibility of PLGA50/50, blending with a small portion of PLLA is required for easy fabrication and collagen modification. Scaffolds made of blended materials by freeze‐drying procedure with the surface modified by cross‐linked Type‐II collagen were demonstrated as the ideal templates for chondrocyte seeding in our study.
Levamisole Treatment Enhances Protective Antibody Response to Hepatitis B Vaccination in Hemodialysis Patients
Authors: Kayataş Mansur
Published: March 2003

Abstract: Hemodialysis shows a high risk for hepatitis B infection, and hepatitis B virus (HBV) vaccination has now become a routine procedure. Unfortunately, 40% to 50% of hemodialysis patients do not have adequate protective antibodies against the HBV vaccination which is thought to be due to depressed cell mediated immunity. Levamisole has been reported to stimulate depressed T‐cell activity and enhance B lymphocyte function and restore delayed hypersensitivity reactions in immune‐depressed patients. We studied the effects of levamisole, an immunomodulatory agent, on the protective antibody response of hemodialysis patients to the HBV vaccination. Our hemodialysis patients with negative anti‐HBs antibody routinely received 40 μg doses of recombinant HBV vaccine intramuscularly at 0, 1, and 6 months, and we followed serum anti‐HBs levels. Patients with a serum antibody level of >10 mIU/ml were considered as responders. Study groups were classified as follows. Group 1 was comprised of 96 chronic hemodialysis patients with negative anti‐HBs and HBV core antibody (52 male, 44 female, mean age of 45 ± 15 years and mean hemodialysis duration of 46 ± 40 months) who received HBV vaccination; 55 patients (57%) were found to be responders. Group 2 was comprised of 19 randomly selected patients who had never received hepatitis B vaccine (13 male, 6 female, mean age of 42 ± 14 years, mean duration of hemodialysis 31 ± 27 months) and who were started on an HBV vaccination protocol with levamisole per os 80 mg after each hemodialysis session for 4 months and followed up on serum anti‐HBs levels. Seventeen of the patients completed this levamisole treatment. Fourteen of the 17 patients had the levels of the protective serum antibody indicating a higher response rate when compared with patients who did not receive levamisole (82% versus 57%, respectively, p < 0.05). Group 3 was comprised of 19 patients randomly selected from persons who did not respond to previous vaccination programs (10 male, 9 female, mean age of 51 ± 14 years, mean duration of hemodialysis 41 ± 31 months). A second HBV vaccination program was started with the same levamisole protocol. In this group, 18 patients completed this treatment model. Fourteen of them responded to the vaccination model. In Group 4, a second HBV vaccination program was applied without levamisole to 20 randomly selected persons who did not respond to the previous routine vaccination program (12 male, 8 female, mean age of 53 ± 17 years, mean duration of dialysis 51 ± 38 months). Only 3 of them responded to a second vaccination program. Comparing Group 3 with Group 4, there was a higher responder rate to HBV vaccination (77% versus 15%, respectively, p < 0.0001). These results show that levamisole treatment increases the response rate to the first HBV vaccination and of the previously unresponsive cases by modulating possible cellular immune response.
Devices for Noninvasive Transcranial Electrostimulation of the Brain Endorphinergic System: Application for Improvement of Human Psycho‐Physiological Status
Authors: Lebedev Valery P. , Malygin A.V. , Kovalevski A.V. , Rychkova S.V. , Sisoev V.N. , Kropotov S.P. , Krupitski E.M. , Gerasimova L.I. , Glukhov D.V. , Kozlowski G.P.
Published: March 2003

Abstract: It is well known that deficit of endorphins plays an important role in disturbances of human psycho‐physiological status. Previously, we revealed that brain endorphinergic structures have quasiresonance characteristics. On the basis of these data, a method of activation of the brain endorphinergic structures by means of noninvasive and rather selective transcranial electrostimulation (TES) as a kind of functional electrical stimulation (FES) was elaborated. New models of TES devices (TRANSAIR) were developed for indoor and outdoor usage. To increase the efficacy of TES, the frequency modulation according to normal distribution in the limits of the quasiresonance characteristics was put into operation. The blind and placebo‐controlled (passive and active placebo) study was produced to estimate the TES effects on stress events and accompanied psycho‐physiological and autonomic disturbances of different intensities on volunteers and patients in the following groups: everyday stress and fatigue; stress in regular military service and in field conditions; stress in the relatives of those lost in mass disaster; posttraumatic stress (thermal burns); and affective disorders in a postabstinence period. Some subjective verbal and nonverbal tests and objective tests (including heart rate variability) were used for estimation of the initial level of psycho‐physiological status, which changes after TES sessions. It was demonstrated that fatigue, stress, and other accompanied psycho‐physiological disturbances were significantly improved or abolished after 2–5 TES sessions. The TES effects were more pronounced in cases of heavier disturbances. In conclusion, activation of the brain endorphinergic structures by TES is an effective homeostatic method of FES that sufficiently improves quality of life.
An Implantable Two Channel Drop Foot Stimulator: Initial Clinical Results
Authors: Kenney Laurence , Bultstra Gerrit , Buschman Rik , Taylor Paul , Mann Geraldine , Hermens Hermie , Holsheimer Jan , Nene Anand , Tenniglo Martin , Van der Aa Hans , Hobby John
Published: March 2003

Abstract: This article reports preliminary results of pilot studies of a new implantable two channel drop foot stimulator. The stimulator consists of an externally worn transmitter inductively coupled to an implanted receiver unit located in the lower leg, lateral and distal to the knee. The receiver is connected to electrodes located under the epineurium of the deep and the superficial peroneal nerves. Stimulation is triggered by detection of heel lift and terminated at heel strike in a manner similar to surface mounted systems. The location of the electrodes allows for a degree of selectivity over the resultant moment about the ankle joint that is not possible with surface stimulation of the common peroneal nerve. The two subjects used the stimulator on a regular basis and showed increases in walking speed of between 10% and 44% when compared to their baseline measurements. Isometric tests have demonstrated that the stimulator allows selective and repeatable stimulation of ankle joint muscles.
Thrombolytic Therapy with Tissue Plasminogen Activator for the Treatment of Nonstructural Malfunction of Bileaflet Cardiac Valve Prostheses
Authors: Teshima Hideki , Hayashida Nobuhiko , Nishimi Masaru , Tayama Eiki , Fukunaga Shuji , Tomoeda Hiroshi , Chihara Shingo , Enomoto Naofumi , Kawara Takemi , Aoyagi Shigeaki
Published: March 2003

Abstract: This study was conducted to determine the effect of thrombolytic therapy with tissue plasminogen activator (t‐PA) for nonstructural malfunction of bileaflet cardiac valve prostheses. Twenty‐seven patients with bileaflet prosthetic valve malfunction diagnosed by a combination of cineradiography and transthoracic echocardiography were treated with the administration of intravenous t‐PA. The treatment resulted in complete success in 55.6% (15 of 27), partial success in 22.2% (6 of 27), and no change in 22.2% (6 of 27). In the complete success and partial success groups, the condition of the patients in 85.7% (18 of 21) of the cases improved within 24 h after the administration of t‐PA. Six cases in whom thrombolytic therapy was instituted more than 1 month (ranged from 1 to 38 months, mean 14.7 months) after the diagnosis of prosthetic valve malfunction showed significantly less effectiveness of thrombolytic therapy with t‐PA. Only one patient (3.7%) had a major complication (thromboembolism) after t‐PA treatment. The results suggest that thrombolytic therapy with t‐PA in patients with nonstructural malfunction of bileaflet cardiac valve prostheses is effective with low incidence of complication when the treatment is instituted early after the diagnosis.
Flow Visualization Study to Investigate the Secondary Flow Behind the Impeller in the Gyro Centrifugal Pump
Authors: Ichikawa Seiji , Nonaka Kenji , Linneweber Joerg , Kawahito Shinji , Motomura Tadashi , Ishitoya Hiroshi , Mikami Minoru , Nishimura Ikuya , Glueck Julia , Shinohara Toshiyuki , Nosé Yukihiko
Published: March 2003

It is the goal of this section to publish material that provides information regarding specific issues, aspects of artificial organ application, approach, philosophy, suggestions, and/or thoughts for the future.

Abstract: The Gyro permanently implantable pump consists of a sealless pump housing and an impeller supported with a double pivot bearing. The secondary vanes are attached to increase the secondary flow to avoid thrombus formation behind the impeller. Flow visualization studies using an oil film method were performed on three types of impellers: no secondary vanes, 0.5 mm height secondary vanes, and 1.0 mm height secondary vanes. Comparison studies of these impellers were performed on the surfaces of the impeller bottom and bottom housing. Regarding the surface of the impeller bottom, the impeller with no secondary vanes had the least stagnant areas around the shaft. On the other hand, the impeller having 1.0 mm height secondary vanes had the most distinguished flow lines on the bottom housing. Overall, the impeller secondary vanes with a height of 0.5 mm (current design) seemed to create the most effective secondary flow.
Adsorption of Inflammatory Cytokines Using a Heparin‐Coated Extracorporeal Circuit
Authors: Fujita Masanori , Ishihara Masayuki , Ono Katsuaki , Hattori Hidemi , Kurita Akira , Shimizu Masafumi , Mitsumaru Atsuhiro , Segawa Daisuke , Hinokiyama Kazuhiro , Kusama Yoshimasa , Kikuchi Makoto , Maehara Tadaaki
Published: March 2003

Abstract: Cardiopulmonary bypass (CPB) surgeries cause an increase in plasma inflammatory cytokines, such as tumor necrosis factor‐α (TNF‐α) and interleukin‐6 (IL‐6) along with whole‐body inflammatory responses. The inflammatory responses during a CPB treatment are reduced when using a heparin‐coated extracorporeal circuit. Because many cytokines, growth factors, and complements are known to interact with heparin, the reduction of inflammatory responses by a heparin‐coated circuit is likely to depend on this heparin‐binding nature of the inflammatory cytokines. In this study, the inflammatory cytokines, TNF‐α and IL‐6, in fetal bovine serum (FBS) bound to a heparin‐agarose beads (heparin beads)‐column and the adsorptions were competitively inhibited on addition of heparin in a concentration‐dependent manner. TNF‐α in FBS required a higher concentration of heparin (50% concentration inhibition [IC50] > 20μg/ml) to inhibit adsorption to the heparin beads‐column compared with IL‐6, probably because of a stronger interaction between TNF‐α and heparin‐beads. TNF‐α and IL‐6 concentrations in human heparinized blood significantly increased after a CPB treatment. Although the adsorbed amount of IL‐6 onto the heparin‐coated circuit was low (less than 6% of free circulating IL‐6), a significant amount of TNF‐α adsorbed onto the circuit (23.9–755% of free circulating TNF‐α). Therefore, the adsorption of inflammatory cytokines, especially TNF‐α, onto the inner heparin‐coated surface of an extracorporeal circuit may partly account for a reduction in inflammatory responses.
The Application of Quantitative Oil Streaking to the HeartQuest Left Ventricular Assist Device
Authors: Lemire P.P. , McDaniel J.C. , Wood H.G. , Allaire P.E. , Landrot N. , Song X. , Day S.W. , Olsen D.
Published: March 2003

Abstract: Methods of flow visualization using oil streaking are established techniques for investigating surface shear and near wall flow patterns. Recent studies have used an array of oil dots on a surface which form streaks when exposed to shear forces. This method is generally qualitative, but it is possible to make quantitative measurements of the shear if the oil streaks have been calibrated. This paper presents the application of a quantitative oil streak method to the HeartQuest left ventricular assist device (LVAD). An array of dots was applied to the top housing of the pump, yielding quantitative values for the shear and qualitative patterns of the near wall flow in that region. The results were used to locate regions likely to promote thrombosis, such as stagnation points or recirculation regions. Regions of high shear, where hemolysis might occur, also can be identified with this method. In addition to being an important design technique, quantitative oil streaking assisted in the verification of computational fluid dynamics results within the HeartQuest LVAD.