bluuebunny/crossref_metadata_2025 huggingface dataset:
High Shear Rate Hemofiltration: Influence of Fiber Dimensions and Shear Rates
Authors: Gupta B. B. , Ding L. H. , Jaffrin M. Y.
Published: November 2008

Abstract: The variation of ultrafiltration flow rate (QF) at high transmembrane pressure with inlet wall shear rate (γW) was found to be proportional to γW, with n ranging from 0.45 to 0.55, when γW increases up to 4,500 s‐1. To test whether long filters operated at high shear rates were more efficient than shorter ones for the same inlet blood flow, we made experiments with 10‐and 20‐cm filters with same number of fibers (550) at various shear rates from 700 to 3,000 s‐1. The filtration rates provided by the 20‐cm filter were found to be 5‐15% larger than those provided by two 10‐cm filters arranged in parallel and 10‐20% smaller than those provided by two 10‐cm filters arranged in a series. The explanation lies in the rapid decay of QF with distance from the inlet due to the developing concentration boundary layer. When pulsations are imposed on the inlet blood flow, the filtration rate was seen to increase by 10‐20%, and the effect of plugging was seen to decrease in small‐area hemofilters.
In Vitro Evaluation of a Bioartificial Pancreas Under Various Hemodynamic Conditions
Authors: Moussy Francis , Rouchette Jeanne , Reach Gérard , Cannon Robert , Jaffrin Michel Y.
Published: November 2008

Abstract: A bioartificial pancreas in which isolated islets of Langerhans are placed between two polyacrylonitrile membranes, blood circulating successively above the upper and below the lower membranes following a U‐shaped circuit, has been developed. The two parts are connected by an outer loop consisting of a thin tubing. The length of this tubing determines the magnitude of the flow rate of blood through the device. The aim of this work was to determine experimentally the optimal configuration of the system containing isolated rat islets and a Krebs buffer circulating through the device. The amount of insulin released by the bioartificial pancreas was determined during a 20‐mM square‐wave glucose stimulation. First, the inlet pressure was set at 100 mm Hg, and the effect of the length of the tubing was investigated with two devices perfused simultaneously. For a short tubing (flow rate, 20 ml/min), a sharp increase in insulin release in response to glucose was observed; it increased within 4 min from 217±50 to 761±237 μU/500 islets/min (p<0.05), the peak value being reached at 11±2 min following the beginning of the stimulation. For a long tubing (flow rate, 3 ml/min), the increase in insulin release was more sluggish. It increased from 133±53 to 222±43 μU/500 islets/min at 4 min, the peak value being reached only at 20±3 min. These data are consistent with a more efficient diffusional transfer of insulin in the case of the high circulating flow. In a second series of experiments, the two chambers were perfused simultaneously at the same flow rate, set by a peristaltic pump (3 ml/min). Here, the kinetics of insulin release were slightly but not significantly faster when the chamber was set up with a long connector, producing a larger contribution of ultrafiltration to the transfer of glucose and insulin across the membranes. Therefore, a short connector yields better glucose‐insulin kinetics when the device works at a set inlet pressure that might mimic the condititons of in vivo implantation. Furthermore, this design should be less thrombogenic.
Selective Removal of Triglyceride‐Rich Lipoproteins by Plasmapheresis in Diabetic Patients with Severe Hypertriglyceridemia
Authors: Ito Hiroo , Naito Chikayuki , Hayashi Hiroshi , Kawamura Mitsunobu , Miyazaki Shigeru
Published: November 2008

Abstract: Two diabetic patients with marked intractable hypertriglyceridemia under treatment with hemodialysis for chronic renal failure were treated by either an apolipoprotein B‐dependent removal of lipoproteins using dextran sulfate cellulose column plasmapheresis or a sizedependent removal of lipoproteins using hollow‐fiber filtration plasmapheresis. In one patient, a column packed with hollow fibers was used as a plasma separator and a dextran sulfate cellulose column as an adsorbent. In another patient, because the hollowfiber column did not separate plasma from whole blood, a centrifuge‐type blood cell separator was used for the plasma separation. The amounts of plasma cholesterol, triglycerides, and phospholipids removed by plasmapheresis were 30%, 33%, and 30%, respectively, when the combination of a hollow‐fiber column and a dextran sulfate cellulose column was used. Corresponding values were 31%, 29%, and 27%, respectively, when the combination of the centrifuge‐type blood cell separator and the hollow‐fiber column was used. The efficiency of lipid removal was almost the same with both techniques. As for plasma separation, the centrifuge‐type blood cell separator was more efficient than the hollow‐fiber column. Some losses of albumin and platelets were observed when combination plasmapheresis using the centrifuge‐type blood cell separator and the hollow‐fiber column was performed. In conclusion, we prefer the centrifuge‐type blood cell separator to the hollow‐fiber column for plasma separation of marked hypertriglyceridemia. The second filter must be chosen for each patient according to the size of the lipoproteins.
The Effects of PGI2 Analog (OP‐41483) on Perfused Porcine Liver
Authors: Kimoto Michio , Shimahara Yasuyuki , Ikai Iwao , Wakashiro Shigetaro , Ozaki Nobuhiro , Tatsumi Yoshio , Tanaka Akira , Kamiyama Yasuo , Yamaoka Yoshio , Ozawa Kazue
Published: November 2008

Abstract: The effects of a prostacyclin analog OP‐41483 on energy metabolism were studied in an isolated porcine liver perfused with human blood for 8 h. OP‐41483 was administered intravenously at a rate of 0.3 μg/kg/min during the procurement and into the perfusate at a rate of 1.0 μg/min during perfusion. Acetoacetate, ß‐hydroxy‐butyrate, lactate, and pyruvate were measured before perfusion and at 1,2, 3, 5, and 8 h after perfusion, from which values the ketone body ratio (acetoacetate/ß‐hydroxybutyrate, KBR), reflecting the redox state of liver mitochondria, was calculated. In the OP‐41483 group, KBR increased rapidly from 0.34 to 0.95, 1.61, 1.51, 2.35, and 2.04, and lactate decreased rapidly from 9.81 to 6.30, 4.51, 3.22, 2.39, and 1.33 mmol/L at the respective hours after perfusion. There were significant differences after 3 h of perfusion as compared with the control group (p<0.05). These results suggest that administration of OP‐41483 causes an increase in mitochondrial NAD+/NADH ratio (oxidized and reduced forms of free nicotinamide‐adenine dinucleotides), leading to an enhancement of the metabolic capacity of the perfused liver.
The Effect of Antihypertensive Drugs on Protein Adsorption, Platelet Adhesion, and Blood Coagulation Toward an Artificial Surface
Authors: Sharma Chandra P. , Chandy Thomas
Published: November 2008

Abstract:Protein adsorption and platelet adhesion are two important biological processes arising at the bloodprosthetic interface. The ability of certain antihypertensive and anticholesterol drugs, namely, clonidine, hydralazine, sembrina, frusemide, clofibrate, sorbitrate, thyroxine, etc., to modulate the surface‐induced platelet adhesion to polycarbonate substrate was investigated using washed calf platelets in the presence and absence of fibrinogen. This study also demonstrated the changes in protein‐surface binding with these drugs using electrophoretic techniques. It seems that the addition of these drugs to the polymer‐protein system increased the level of surface‐bound albumin variably. These drugs also reduced the fibrinogen surface concentration and inhibited the surface‐induced platelet adhesion to variable degrees. Therefore, it may be possible that the enhanced albuminsurface concentration, or reduced fibrinogen‐surface binding, in the presence of these drugs may be one of the parameters for a reduced platelet‐surface attachment, which may also improve the blood compatibility of the substrate. A better understanding of the mechanism of these drugs under in vivo conditions is needed to correlate these findings.
Kinetic Modeling of Intradialytic and Interdialytic pH Shifts During and After Acetate and Bicarbonate Hemodialysis
Authors: Monti Jean‐Pierre , Sarrazin Marcel Y. , Baz Mahmoud , Murisasco Antoine , Crevat Aimé D. , Elsen Raymond
Published: November 2008

Abstract: A kinetic model involving intraerythrocytic and whole blood H+ concentrations during and after bicarbonate and acetate hemodialysis is proposed to account for experimental data. A two‐compartment model appeared to be the simplest kinetic model to explain the decrease in proton concentration during bicarbonate hemodialysis and its increase between two dialysis sessions, whether acetate or bicarbonate. This model takes into account the hemoglobin buffer power and the cellular metabolic acidosis. During acetate hemodialysis, one must introduce a new compartment to explain the initial increase in H+ concentration in erythrocytes. This compartment, which generates protons, seems to correspond to the carbonic anhydrase cycle. The various parameters obtained show no significant variations between patients receiving bicarbonate hemodialysis. For acetate hemodialysis, the model describes equally well patients with a great initial increase in H+ concentration and those with a slight initial increase. The variations observed in the parameters are due mainly to the carbonic anhydrase compartment. It is suggested the magnitude of this initial increase and the degree of acetate intolerance are correlated.
The Effect of Left Ventricular Bypass on the Right Ventricular Function: Experimental Analysis of the Effects of Ischemic Injuries to the Right Ventricular Free Wall and Interventricular Septum
Authors: Nishigaki Kyoichi , Matsuda Hikaru , Hirose Hajime , Nakano Susumu , Ohtani Masakatsu , Ohkubo Nobukazu , Matsuwaka Ryousuke , Kawashima Yasunaru
Published: November 2008

Abstract: The right ventricular (RV) function during left heart bypass (LHB) was examined in open‐chest anesthetized mongrel dogs (average weight, 11.8 kg). The LHB was carried out by a left ventricle (LV) to femoral artery bypass using a centrifugal pump for 90 min, and the bypass flow was kept maximum to obtain almost complete decompression of the LV. The RV function was evaluated by hemodynamic parameters and pressure‐dimension (sonomicrometry) relationship at pre‐LHB (control) and 30, 60, and 90 min after LHB (LHB‐30, LHB‐60, and LHB‐90). The materials were divided into three groups after LHB‐30: intact heart (group 1, n = 5), RV free wall ischemia (group 2, n = 5), and interventricular septum (IVS) ischemia group (group 3, n = 8). No significant changes in mean right atrial pressure (mRAP), RV end‐diastolic pressure (RVEDP), RV maximum derivative pressure, or RV fractional shortening (RVFS) were found between pre‐LHB and post‐LHB in groups 1 and 2. On the contrary, group 3 showed significant increases in mRAP and RVEDP, and a decrease in RVFS at LHB‐90 compared to both pre‐LHB and LHB‐30. The RV end‐systolic dimension (percentage of pre‐LHB) showed significant increases at LHB‐90 compared to LHB‐30 in groups 2 and 3. These results indicate that the LHB itself does not depress the RV function in the intact heart and in the RV free wall ischemic heart, while the impairment of the IVS during LHB appears to lead to RV dysfunction.
Electrical Control of Gastric Emptying in Denervated and Reinnervated Canine Stomach: A Pilot Study
Authors: Grundfest‐Broniatowski Sharon , Davies Charles R. , Olsen Eric , Jacobs Gordon , Kasick Jerald , Chou Samuel M. , Nose Yukihiko , Hermann Robert E.
Published: November 2008

Abstract: Gastric emptying of solids is abnormally slow after vagotomy. To determine whether it was possible to accelerate emptying by electrical stimulation either of the gastric wall directly or of a “foreign” nerve brought in to reinnervate the stomach, eight dogs underwent truncal vagotomy (TV); five of the dogs received intercostal nerve muscle pedicle (NMP) implants. Gastric atony was demonstrated postoperatively in all animals up to 4. months later by means of radiological contrast studies. After allowing time for neurotization to occur (mean 78 days), the cervical vagi were stimulated to confirm that TV was complete. Gastric peristalsis, intraluminal pressures, and emptying were assessed during stimulation of the NMPs and of the gastric wall, followed by sacrifice for histologic study. Neither reinnervation alone nor stimulation of the NMPs improved emptying. Although viable somatic nerve was found in the gastric wall, nerve sprouting was not. By contrast, stimulation of the gastric wall with trains of pulses (20 Hz, 2–10 ms, 2–5 mA) evoked peristalsis in all animals. We conclude that somatic nerve tissue cannot produce functional reinnervation of a visceral organ; however, direct muscular stimulation can accelerate gastric emptying after TV.
Artificial Heart Valves: Improved Blood Compatibility by PECVD a‐SiC:H Coating
Authors: Bolz A. , Schaldach M.
Published: November 2008

Abstract:Implants are steadily increasing in importance as substitutions for body functions. With the present state of the art, the limitations of the application of cardiovascular implants are due to insufficient performance of biomaterials. Present research in this field is being concentrated on efforts to improve the thrombus resistance of conventional materials by coating with semiconducting materials to actively influence the electrochemical interaction between the condensed matter and blood proteins. Based on an electrochemical model of the interaction of fibrinogen with an artificial surface and the resulting requirements for improving hemocompatibility, a coating of amorphous hydrogenated silicon carbide deposited by plasma‐enhanced chemical vapor deposition (PECVD) is presently under evaluation as a special coating material for cardiovascular prostheses and is herein described (1). In particular, first results are published concerning the optimum deposition parameters in the PECVD process and cell culture tests. Experimental results of comparative partial thromboplastin time studies serve the purpose of proving the validity of the electrochemical reaction model referring the hemocompatibility of implantable materials to their semiconducting surface properties. The aim of this article is to demonstrate a feasible method for an antithrombogenic surface modification based on doped amorphous silicon carbide films that is in full conformance to the above mentioned model.
A Two‐Phase Fluid Volume Compensation Chamber for an Electric Ventricular Assist Device
Authors: Lamson Theodore C. , Ojan Ourmazd S. , Geselowitz David B. , Tarbell John M.
Published: November 2008

Abstract: A volume compensation chamber is a device used to reduce large pressure fluctuations created in electric ventricular assist devices during the emptying and filling of the blood sac. In this study, the effect of motor casing pressure variation (pressure swing) on the performance of the Penn State electric ventricular assist device (EVAD) was investigated. Design criteria were established for the maximum pressure swing tolerated by the EVAD and the optimal mean chamber pressure at which to operate. At the chosen mean chamber pressure of ‐15 mm Hg, it was found that pressure swing should be maintained below 45 mm Hg. A two‐phase fluid volume compensation chamber was developed that reduced the pressure swing enough to ensure adequate pump performance. The device consists of a metal chamber with a high‐heat‐flux porous coating applied to the inside surface. The chamber uses Freon as the working fluid and is isolated from the EVAD by a metal bellows. It was found that the high‐flux coating significantly reduces the pressure swing, in some cases by as much as 50% when compared with an identical chamber with no coating. In the coated chamber the pressure swing was maintained between 22 and 30 mm Hg at a beat rate of 60 beats/min, for a wide range of Freon volumes (4–38 ml). Even at 100 beats/min the pressure swings obtained with the coated chamber are well within an acceptable range.
A New Total Implantable Artificial Heart
Authors: Martens Jörn
Published: November 2008

Abstract: A new kind of total implantable artificial heart (TIAH), developed by the author, offers miniaturization with good hemodynamic and physiologic properties. The heart has two units of function, and each has two blood sacs, compressed and expanded by twos, that are filled from one circulation and push out the blood in the other circulation, one after the other. Therefore, the blood flow is continuous and modulated, regulated by pneumatic controlled membrane valves. Shaped plates mechanically synchronized by a pushing rod control compression and expansion of the blood sacs. Starling, atrium, Windkessel, and Anrep effects are guaranteed by construction. The heart can be used for bridging toward transplantation, for definitive substitution of the heart, and for a new kind of therapy‐“extracorporeal regeneration of organs.”
Selective Removal of Anti‐Acetylcholine Receptor Antibodies and IgG In Vitro with an Immunoadsorbent Containing Immobilized Sulfathiazole
Authors: Yamamoto Yuich , Sameshima Tadashi , Akaike Toshihiro
Published: November 2008

Abstract: Adsorption therapy, which treats the autoimmune disease by the selective removal of pathogenic substances from the blood, is an active subject. In this therapy, bioactive molecules such as antigen, antibodies and protein A are usually used as affinity‐ligands. The disadvantages of using these substances as affinity‐ligands are the availability, sterilizability, and ability to cause antigenic reactions. After surveying hundreds of synthetic compounds, it was found that polyacrylic beads [Eupergit C (EC)] immobilized covalently with sulfathiazole (ST) are an ideal biomimetic ligand for the selective adsorption of IgG (24.3 ± 0.4 mg IgG/g wet beads). In an in vitro study, this adsorbent selectively removed the antiacetyl‐choline (AChR) receptor antibody of myasthenia gravis (MG) patients. Further experiments demonstrated that the Fab fragment was adsorbed three times more efficiently than the Fc fragment of IgG.
Chlorine Dioxide Gas Sterilization of Oxygenators in an Industrial Scale Sterilizer: A Successful Model
Authors: Jeng David K. , Woodworth Archie G.
Published: November 2008

Abstract: Artificial organ oxygenators, with large surface areas and complicated structures, were sterilized using chlorine dioxide gas in an industrial scale sterilizer. Bacillus subtilis var. niger ATCC 9372 biological indicators (BI) (106 spores/BI) planted in the artificial organs were reproducibly sterilized in a designed cycle schedule with a 30‐min dwell time with a chlorine dioxide gas concentration of approximately 30 mg/L in 80 to 85% relative humidity at 30d̀C. The D value (time required for 90% spore inactivation under specific conditions) was estimated to be 4.4 min. Chlorine dioxide was not detected after poststerilization aeration. The intravenous median lethal dose (LD50) of chlorine dioxide derivatives, chlorite and chlorate, in rats was found to be 112.8 and 2,228.6 mg/kg, respectively. In an immediate hypersensitivity test, chlorine dioxide gas‐treated ovalbumin and bovine serum albumin, unlike ethylene oxide gas‐treated proteins, did not cause sterilant‐specific IgE‐mediated hypersensitivity reactions in rats. Results of an Ames mutagenicity test on chlorine dioxide and on the extracts of the chlorine dioxide gas‐exposed oxygenators were negative.
Glued Carbon Fiber Electrodes for Diaphragm Pacing
Authors: Kimura Motohiko , Sugiura Toshifumi , Fukui Yoshihito , Togawa Morio , Harada Yukio
Published: November 2008

Abstract: Carbon fibers with fibrin glue were used as electrodes for diaphragm pacing. The electrodes were applied to three mongrel dogs and the effectiveness was tested. The carbon leads were glued to phrenic nerves by means of the fibrinogen and thrombin bilaterally. The tidal volumes and threshold current level for stimulation were measured at various time up to 9 weeks after implantation. Effective contraction of diaphragm were observed for 9 weeks. By using this electrode, the exfoliation of the nerve is not necessary, the nerve can be maintained in an intact state, and the risk of the implanting operation can be minimized.
Effects of Hypertonic Peritoneal Dialysis Solutions on Neutrophil Superoxide Production
Authors: Zhou Fang Q. , Manahan Ferdinand J. , Yu Alex W. , Rahman Mohamed A. , Nawab Zeenat M. , Fisher Kenneth A. , Ing Todd S.
Published: November 2008

Abstract. Superoxide produced by neutrophils plays an important role in the killing of bacterial pathogens. The effects of glucose‐containing peritoneal dialysis solutions on superoxide production by canine and human neutrophils were studied. A significant decrement in superoxide generation was noted with the 2.27% and 3.86% glucose solutions. The results suggest that hypertonic peritoneal dialysis solutions curtail neutrophil superoxide generation.
Filtration of Fresh Frozen Plasma Used As Substitution Fluid in Plasma Exchange in Order to Remove Microaggregates
Authors: Akamatsu Koichi , Tanaka Yoshikazu , Tada Kouji , Ohshima Kanji , Ohta Yasuyuki
Published: November 2008

Abstract: Freshly melted fresh frozen plasma (FFP) contains a large number of particles smaller than 20 urn in diameter. These particulate materials (microaggregates) consist of aggregated triglyceride‐rich lipoproteins (LA) and precipitable aggregates closely resembling fibrin (FA). Both LA and FA injected into a rat̂s tail vein were trapped in the lung and formed emboli in the pulmonary arterioles. To prevent the passage of these microaggregates into the systemic circulation, a new circuit was devised for plasma exchange containing a filter with a pore size of 0.2 μm. In 17 patients with fulminant hepatitis who received plasma exchange transfusions and subsequently died and were autopsied, the incidence of pulmonary complications was significantly lower in the 12 patients who received filtered FFP. According to these results, the possibility of pulmonary complications due to micro‐embolism developed by microaggregates in FFP should be taken into account when a large amount of FFP is repeatedly infused into critically ill patients.
Collagen Cross‐Linking and Resorption: Effect of Glutaraldehyde Concentration
Authors: Roe Simon C. , Milthorpe Bruce K. , Schindhelm Klaus
Published: November 2008

Abstract: Cross‐linked collagen bioprostheses usually are designed to be inert and nonresorbable, resulting in fatigue and wear failure in high‐stress environments. Eventual replacement of the implant, although minimizing strength loss during resorption, would result in a graft with reparative ability. Kangaroo tail tendon (KTT) partially cross‐linked with glutaraldehyde (GA) was evaluated in vitro for resistance to bacterial collagenase digestion and in vivo for biocompatibility and resorbability in an intramuscular implant assay. Cross‐linking was quantified by thermal denaturation studies. Incomplete cross‐linking was achieved with concentrations of GA >0.1% (w/v). KTT cross‐linked in <=0.05% GA were collagenase resistant being incompletely digested after 240 h. Cross‐linking of KTT with low concentrations of GA resulted in partial collagenase resistance and slowed resorption.
Long–Term Respiratory Assistance Using a Right Ventricular Assist Device System and a Membrane Oxygenator
Authors: Tatsumi Eisuke , Takano Hisateru , Taenaka Yoshiyuki , Nakatani Takeshi , Noda Hiroyuki , Kinoshita Masayuki , Sekii Hiroyoshi , Yagura Akihiko , Sasaki Eisaku , Akagi Haruhiko , Akutsu Tetsuzo
Published: November 2008

Abstract: A new method for long–term respiratory assistance using a right ventricular assist device (RVAD) system and a membrane oxygenator (MO) was designed and evaluated. An air–driven RVAD was implanted between the right atrium and the pulmonary artery in five goats and art MO was set on the outlet conduit of the RVAD 2 weeks postoperatively. Two types of MOs [the SciMed (Life Systems) silicone sheet MO and a prototype MO using a novel multilayered composite membrane] were used in this study. Respiratory support with this system under systemic heparinization could be conducted for 4–8 days without major problems accompanied with conventional extracorporeal membrane oxygenation (ECMO) such as surgical bleeding, destruction of the blood components, serum leakage, insufficient bypass flow, and fatal systemic thrombosis. This method opened the possibility for ECMO to be used as a bridge before lung or heart–lung transplantation.
Criteria for Anatomical Compatibility of the Total Artificial Heart: Computerized Three‐Dimensional Modeling of the Cardiovascular Anatomy
Authors: Chatel Didier , Martin‐Bouyer Yves , Vicaut Eric , Bouchoucha Hassen , Achard François , Sablayrolles Jean‐Louis , Carpentier Alain
Published: November 2008

Abstract: A quantitative study of cardiovascular anatomy was performed by obtaining three‐dimensional reconstructions from regular computed tomography scan images in 15 patients, all candidates for heart transplantation. Volumetric estimates of the cardiovascular structures were obtained from these three‐dimensional reconstructions using data directly related to total artificial heart (TAH) implantations. By using computerized three‐dimensional modeling of these structures, reproducible measurements of the parameters defining the shape and the anatomical connections of the intrathoracic space available for TAH implantation could be derived. The results are intended to be used for both technical and clinical applications such as computer‐assisted drawing of the pericardial cavity and the anatomical connections (useful for improving the design of TAH) and combined statistical calculations (multiple regressions, cluster algorithm) of the measurement results, which will then enable the best selection to be made among two or three TAH models for each patient.
Xenotransplantation of Microencapsulated Canine Islets into Diabetic Rats
Authors: Chen Chia‐Fu , Chern Hwa‐Tzong , Ieu Fur‐Jing , Chang Tzu‐Ming , Shian Lee‐Ren , Sun Anthony M.
Published: November 2008

Abstract: Islets of Langerhans were isolated in high yields from canine pancreata. In the procedure, the pan‐creata were perfused and digested with collagenase, and the islets were then purified on histopaque density gradients. As many as 60,000 islets were isolated from a single pancreas. Islets were encapsulated in alginate‐polylysinealginate membranes with the aid of an air‐jet droplet generator. In vitro studies demonstrated that the isolated and encapsulated islets secreted insulin in response to glucose and IBMX challenge for at least 9 weeks. In in vivo studies 6 diabetic Wistar rats were transplanted with 5,000 to 8,000 encapsulated islets each. The diabetic condition was reversed in all recipients for up to 112 days. In control animals, which received free, unencapsulated islets, the xenografts remained functional for fewer than 21 days. Microcapsules retrieved from normoglycemic transplant recipients 1 and 2 months posttransplantation were shown to contain viable islet tissue, and no cellular overgrowth was observed on capsular surfaces. The results of the study indicate a considerable clinical potential of microencapsulated canine islet xenografts.
Lysophosphatidylcholine, a Component of Stromal Phospholipids, as a Candidate Vasoconstrictive Factor in Stroma‐Free Hemoglobin
Authors: Nakai Kunihiko , Matsuda Noriko , Ohta Toshio , Amano Miyuki , Takahashi Tsuneo A. , Sakuma Ichiro , Kitabatake Akira , Ito Shigeo , Nakazato Yoshikazu , Sekiguchi Sadayoshi
Published: November 2008

Abstract:Stroma‐free hemoglobin (SFH) contains a trace amount of phospholipids, which has been implicated in the toxic reactions associated with SFH. We analyzed stromal phospholipids by high‐performance liquid chromatography and found that SFH contained small quantities of lysophosphatidylcholine (LPC), which is known to be capable of producing a defect in endothe‐lium‐dependent arterial relaxation, in addition to major classes of constituent phospholipids in red cell membrane. LPC content was determined to be 1.65 nmol/ml (hemoglobin 8.1 g/dl). To evaluate the role of these stromal phospholipids in SFH‐induced vasoconstriction, we next examined the effect of lipids on vascular tone in rabbit aortic strips. Preincubation with the crude lipid extract or the LPC purified from SFH significantly inhibited acetylcholine‐induced relaxation in phenylephrine‐precontracted tissues. The LPC‐induced inhibition was reversed by incubation of the tissues in the absence of lipids, indicating the functional integrity of endothelium. From these results, we propose a possibility that LPC, a component of stromal phospholipids, is a candidate for vasoconstrictive factors present in SFH.
The Next Generation Baylor C‐Gyro Pump: Antithrombogenic “Free Impeller” Design for Long‐Term Centrifugal VAD
Authors: Ohara Yasuhisa , Nosé Yukihiko
Published: November 2008

Abstract: The new generation centrifugal blood pump, the C2 Gyro Pump “Free Impeller Model” specifically designed for long‐term ventricular assistance and a bridge to transplantation, has been developed. In the free impeller design, the impeller was completely freed from mechanical tethers by eliminating the shaft. This unique design allowed the incorporation of a center‐penetrating hole in the impeller, called the center conduit, which accelerates the secondary blood flow from the bottom to the top of the impeller. During in vitro performance tests, two characteristic impeller motions, called floating mode and wandering rotational axis, were observed. In the floating mode, the impeller seemed to be floating without touching the pump casing and resulted in the idea of no bearing contact. Also, the rotational axis of the impeller exhibited a small circular motion and illustrated the idea of no stationary area in the blood path. These three characteristics are expected to be advantageous for antithrombogenesity and low hemolysis which are essential for a long‐term centrifugal VAD.
Technology and Clinical Application of Large‐Bore and Implantable Catheters
Authors: Hoenich Nicholas Andrew , Donnelly Peter Kevin
Published: November 2008

Abstract: The access of choice for patients receiving regular dialysis therapy remains the surgically created arteriovenous fistula. In a number of such patients as well as those requiring treatment for acute renal failure, plasmapheresis or hemoperfusion alternative techniques of access are used. Of the techniques used subclavian and femoral catheterization are preferred for short‐term vascular access while in patients requiring long term vascular access the use of a surgically inserted central venous line is favoured. The technology performance and clinical aspects of the use of large bore and implantable catheters are reviewed.
Hemodiabsorption in Treatment of Acute Hepatic Failure and Chronic Cirrhosis with Ascites
Authors: Ash Stephen R.
Published: November 2008

Abstract: Hemodiabsorption is a selective chemical removal process during which blood passes through dialysis membrane packages surrounded by a suspension of fine sorbent particles. The BioLogic‐DT system contains charcoal and cation exchangers in a suspension that passes through dialysate spaces of a cellulosic membrane plate dialyzer. The system has proven effective in treatment of patients with serious drug overdose and has demonstrated positive effects in treatment of stage 4 coma due to hepatic failure. Recently, the charcoal in this system has been preloaded with branch chain amino acids to return these acids to patients while aromatic amino acids are removed. Further improvements include addition of osmotically active agents to the priming fluid and sorbent to increase blood oncotic pressure and transfer of ascitic fluid to blood while ultrafiltration transfers fluid out of the blood. Clinical testing of these improvements is now beginning in patients with ascites and encephalopathy due to chronic hepatic insufficiency and cirrhosis. Future improvements will include protein permeable membranes to increase removal of protein‐bound toxins and addition of hepatic cells downstream from the hemodiabsorption unit.
Serum Hyaluronic Acid and Interleukin‐6 as Possible Markers of Carpal Tunnel Syndrome in Chronic Hemodialysis Patients
Authors: Takasu Shinji , Takatsu Shigeko , Kunitomo Keichi , Kokumai Yoshiaki
Published: November 2008

Abstract: To elucidate the precise mechanism of carpal tunnel syndrome (CTS), serum hyaluronic acid (HA), interleukin‐1β (IL‐1β), interleukin‐6 (IL‐6), and tumor necrosis factor‐α (TNF‐α) were measured in 71 chronic hemodialysis patients with or without CTS and/or shoulder pain. Patients were divided into two groups: Group 1 (n = 40) was the control group, and Group 2 (n = 31) patients had carpal tunnel syndrome, shoulder pain, or both. None of the patients had liver disease, rheumatoid arthritis, other inflammatory disease, or cancer. Serum HA concentrations in Groups 1 and 2 were 106.0 ± 77.5 and 442.6 ± 564.7 ng/dl (mean ± SD), respectively. The difference between the groups was significant (p < 0.01). The serum concentrations of IL‐6 in Group 1 were significantly lower than in Group 2 (p < 0.05); however, there was no significant difference in serum IL‐1β and TNF‐α levels. The mechanisms regulating in vivo synthesis of HA was obscure; however, in vitro studies suggest that inflammatory cytokines may stimulate an increased production of HA. In this study, CTS might be associated with increased serum concentrations of HA, and HA production might be mediated by IL‐6.
Noninvasive Blood Glucose Sensors Based on Near‐Infrared Spectroscopy
Authors: Heise H.M. , Marbach R. , Koschinsky Th. , Gries F.A.
Published: November 2008

Abstract: Research into noninvasive devices for self‐monitoring of blood glucose is mainly based on near‐infrared spectroscopy. Such a device is particularly desirable in the intensive therapy of patients with diabetes mellitus to achieve optimal metabolic control through frequent glucose testing. The state of noninvasive assay technology is presented. Using diffuse reflectance spectra of mucous lip tissue has advantages and drawbacks compared with tissue transmittance experiments. Different approaches have been proposed in the patent literature; however, current technology requires further significant improvements, particularly within the lower normal and hypoglycemic glucose concentration ranges.
An Ultimate, Compact, Seal‐less Centrifugal Ventricular Assist Device: Baylor C‐Gyro Pump
Authors: Ohara Yasuhisa , Makinouchi Kenzo , Orime Yukihiko , Tasai Kimitaka , Naito Kozo , Mizuguchi Kazumi , Shimono Takatsugu , Damm George , Glueck Julie , Takatani Setsuo , Noon George P. , Nosé Yukihiko
Published: November 2008

Abstract: We have developed a compact, seal‐less, allpurpose centrifugal pump, the Baylor C‐Gyro pump, which is intended as a long‐term ventricular assist device (VAD) as well as a cardiopulmonary bypass pump. In attaining this goal, we began with eliminating the shaft seals by adopting a pivot bearing system at the impeller shaft. In addition, a ring magnet encased in the bottom of the impeller was coupled magnetically to a driver magnet placed outside the pump housing (Cl Prototype). This first model yielded satisfactory performance in vitro with a flow rate of 8 L/min against 250 mm Hg at 2,400 rpm, and an index of hemolysis (IH) of 0.0083 g/100 L using bovine blood. In the second model, the C1 Eccentric Inlet Port Model, the inlet bearing support bar in the prototype were eliminated without reducing the prototype's performance. These designs for antithrombogenicity are being tested by the first in vivo experiment, which has lasted for more than 2 weeks.
Prevention of Calcification of Tissue Valves
Authors: Chanda Jyotirmay , Rao S. Bhaskara , Mohanty Mira , Lal Arthur V. , Muraleedharan C. V. , Bhuvaneshwar G. S. , Valiathan M. S.
Published: November 2008

Abstract: In this study an attempt was made to find an optimum method of chemical treatment to prevent the calcification of bioprosthetic heart valves. Bovine pericardium was washed in a 5% sodium chloride solution followed by trypsin (Tr) treatment and was kept in 0. 1% glutaraldehyde (GA) with a gradual increase in concentration up to 0. 25% GA and finally posttreated with a 4% chitosan (Ch) solution. Fresh, 0. 2% GA, 0. 625% GA, and sodium chloride–Tr–GA treated pericardial samples were taken for comparative study. Tensile testing showed comparable strength and elongation at the breaking point for all groups. The thermal shrinkage studies indicated merit of the proposed treatment (5% sodium chloride–trypsinglutaraldehyde treated pericardia with chitosan and without chitosan posttreatment). Collagenase assay showed that all differently treated (GA) materials were equally resistant to collagenase. All samples were implanted subcutaneously in rats for 2, 4, 8, or 12 weeks for calcification study. Morphological and mineral analyses showed complete prevention of calcification in sodium chloride–trypsin–GA–chitosan treated pericardium (Ca was 1. 1 ± 0. 27 mg/g, von Kossa 0) at the 12th week of implantation.
An Intrapleural Lung Prosthesis: Rationale, Design, and Testing
Authors: FAZZALARI FRANCO L. , BARTLETT ROBERT H. , BONNELL MARK R. , MONTOYA J. PATRICK
Published: November 2008

Abstract: Extracorporeal life support (ECLS or ECMO) is standard treatment for severe respiratory failure but poses many contraindications to future lung transplantation. The solution to this dilemma is the implantable gas exchange device (IGED) or artificial lung. Preliminary efforts to create such an artificial lung have been made since 1970 and include designs involving single devices, intravascular devices (i. e., IVOX), and combination heart–lung devices, Stringent requirements govern the design of such a device, the most important of which are high gas exchange efficiency, low resistance to blood flow, and size. This paper describes such a device. It incorporates large diameter inflow and outflow ports in close proximity and a low resistance wound hollow fiber core encapsulated in a compliant outer shell which conserves the work of the right ventricle. In a large animal model (adult sheep) this device was connected in line with the main pulmonary artery in series with the native lungs. This configuration has the advantages of using the lungs as an embolic filter, perfusing the lungs with fully oxygenated blood, and maintaining the integrity of the anatomy necessary for transplant. Laboratory experiments have run >8 h. Preliminary data show that the animals have remained hemodynamically stable while the devices have supported the animals completely by supplying 100% O2 saturation with PO2 values ranging from 250–350 mm Hg. Additionally, this model makes possible the study of respiratory failure without introducing other variables such as extracorporeal circuits or pumps. The other metabolic, endocrine, and reticuloendothelial functions of normal and injured lungs can now be studied more precisely by excluding these variables. Further studies are needed to evaluate this device in chronic (long–term implantation) experiments before clinical application.
Major Findings from the Clinical Trials of the Intravascular Oxygenator
Authors: CONRAD STEVEN A. , Bagley Ann , Bagley Barry , SCHAAP ROBERT N.
Published: November 2008

Abstract: Major clinically relevant findings have been extracted and summarized from the database developed from the international multicenter clinical trials of the intravascular oxygenator (IVOX) as a means for augmenting the deficient blood gas transfer of patients in advanced acute respiratory failure (ARF). Between February 1990 and May 1993, a total of 164 IVOX devices were utilized in 160 clinical trial patients who were hypoxemic and/or hypercarbic while receiving closed system positive pressure mechanical ventilator support at or exceeding generally accepted minimum safe levels of intensity. The average rates of oxygen and carbon dioxide transfer into and out of circulating venous blood by means of the IVOX device varied from 40–70 ml/min. Evidence of patient benefit during IVOX utilization includes improvement in blood gas partial pressures associated with decreased intensity of mechanical ventilation, improved hemodynamics in patients with mechanical ventilator depressed cardiovascular function, and decreased indices of lung dysfunction. Clinically recognized IVOX–related complications or adverse events were reported in 24. 5% of the clinical trials patients. At necropsy examination of 68 clinical trials patients who died during or after I VOX utilization, forensic pathologists reported 4 cases in which IVOX utilization could have been a primary or contributing cause of death. Significant IVOX device mechanical and/or performance malfunction problems were recognized in 29 (17. 7%) of the IVOX devices utilized in clinical trials. IVOX clinical trials data collected and analyzed to date indicate IVOX utilization has a favorable risk/benefit ratio in patients in severe, acute, potentially reversible ARF.
Acute Symptoms During and Between Hemodialysis: The Relative Role of Speed, Duration, and Biocompatibility of Dialysis
Authors: SKROEDER N. RICHARD , JACOBSON STEFAN H. , LINS LARS‐ERIC , KJELLSTRAND CARL M.
Published: November 2008

Abstract: The relationship between hemodialysis (HD) symptoms and dialyzer membrane composition and area, blood–flow, treatment duration, urea removal, ultrafiltration volume, leukocyte activation, and complement generation (C3a) was studied in 20 patients undergoing 234 HD treatments by 12 different modes in random order using Cuprophan, hemophane, or polyamide membranes with small or large membrane areas with high Qb (400 ml/min) and short duration (2 h) or low Qb (200 ml/min) and long duration (4 h). Fewer symptoms occurred during the 2–h HD at high Qb than during the 4–h HD with low Qb (19% vs. 32%, p = 0. 0351). No differences were observed between different dialyzer membranes or areas. More intradialytic symptoms occurred when urea elimination was high than it was low (p = 0. 0044). Leukocyte activation (leukocyte drop) after 15 min of dialysis and complement generation did not influence symptom incidence. Blood pressure changes were mainly influenced by ultrafiltration volume (p < 0. 001). Symptoms between dialyses were determined by urea removal and ultrafiltration. Membrane, area, or Qb were of no importance. Thus, duration of dialysis, urea removal, and demand for ultrafiltration, but not membrane composition, area, or biocompatability, are important for the development of HD–related symptoms.
Experience with the Berlin Heart Assist Device
Authors: GOULLON ANDREAS , RIES DIETMAR
Published: November 2008

Abstract: Different mechanical circulatory support systems (MCSS) have been in clinical use since 1987 to keep patients alive by assisting the heart during cardiac recovery after open heart surgery, myocardial infarction, acute graft failure after heart transplantation, or as a bridge to transplantation in heart transplant candidates. Four different hospitals in Germany used the Berlin Heart Assist Device. Up until 1993, there were 22 patients in the “recovery” group; 4 patients were weaned from the system, and only 1 patient was discharged from the hospital. In 112 patients the Berlin Heart Assist Device was implanted for the purpose of a bridge to transplantation, 68 were transplanted and 46 patients left the hospital. It was concluded that patients may be kept alive with this system for weeks and months after any kind of cardiogenic shock. Complete cardiac recovery may be achieved in patients with early posttransplant graft failure. Reliable prediction of outcome in bridge–to–transplantation patients requires further experience and improvement of system components.
The Vienna Implantable Centrifugal Blood Pump
Authors: SCHIMA H. , TRUBEL W. , WIESELTHALERXY G. , SCHMIDT C. , MÜLLER M. R. , SIEGL H. , LOSERT U. , WOLNER E.
Published: November 2008

Abstract: Because of the inherent disadvantages of membrane pumps, rotary pumps have been increasingly investigated in recent years. As a result of improving biocompatibility, extended assistance with implantable devices is of special interest. Questions arise concerning shear stress, blood traumatization, design of seals, and specific control conditions. In their development of an implantable impeller pump, the Vienna group studied the minimization of hemolysis and thrombus formation by means of numerical simulation, visualization, and in vitro blood evaluation. The latter was revealed to be the most powerful tool for pump evaluation. With optimization of geometry, a hemolysis of in vitro: IH = 0. 008; MIH = 0. 58; and in vivo: 2. 1 to 3 mg% plasma–free hemoglobin could be obtained. For proper control and physiological adaptation, a controller based on a nonlinear and a fuzzy strategy was developed. Furthermore, a method for evaluation of the contractility of the assisted heart during nonpulsatile support was tested by computer simulation. This paper summarizes the evaluation methods used and provide an overview of the results of pump and controller design.
Development of the Marseilles Pulsatile Rotary Blood Pump for Permanent Implantable Left Ventricular Assistance
Authors: MONTIÈS J. R. , HAVLIK P. , MESANA T. , TRINKL J. , TOURRES J. L. , DEMUNCK J. L.
Published: November 2008

Abstract: We have developed a low–speed, double–lobed hypocycloidal pump that furnishes a pulsatile flow without valves. The pump is coupled to a specially designed electric motor. The motor/pump unit is totally implantable and has been extensively tested in vitro and in vivo in animals. Because this pump is volumetric, it is necessary to control speed precisely to avoid overpumping. Our control system, which is based on analysis of the motor current wave form, can detect and prevent negative pressures before they occur. The physical properties and hemocompatibility of several construction materials have been studied to determine their suitability for clinical use. These materials include a graphite substrate, titanium nitrate surface coating, boric carbon, and amorphous diamond. The pumps currently being tested are made of titanium, but clinical versions will be made of composite materials selected from this preliminary study. In vivo testing of this pump confirmed its good hemodynamic performance, low hemolysis rate, and biocompatibility (i. e., low heat, noise, and vibration levels). Animal experiments were terminated after 15 days because of mechanical failure related to the accumulation of blood components on moving parts. A new pump in which the mechanism is completely sealed from the blood flow has been designed and will soon be tested. If this sealed design is effective, the pump should be ready for use as a permanent implantable ventricular assistance device.
Concept, Realization, and First In Vitro Testing of an Intraarterial Microaxial Blood Pump with an Integrated Drive Unit
Authors: ROSARIUS NORBERT , SIEß THORSTEN , REUL HELMUT , RAU GÜNTER
Published: November 2008

Abstract: The intraaortically located microaxial pump represents a promising device for temporary cardiac assistance in terms of efficiency and practicability. Due to well–documented problems arising from the concept of a pump unit being driven by an extracorporeally placed motor via a flexible drive shaft cable, a new pump concept is presented. The cable is replaced by a proximally attached microelectric motor that needs only an extracorporeal power supply.
The Rectus Abdominis Cardiomyoplastic Procedure: Preliminary Results
Authors: WIJNBERG DAVID S. , HENSEN AB G. , GRANDJEAN PIERRE–ANDRE , SCHREUDER JOLANDA A. H. , ROBINSON PETER H. , EBELS TJARK
Published: November 2008

Abstract: The rectus abdominis myofascial flap (RAMF) was investigated as a viable alternative to the latissimus dorsi flap for dynamic cardiomyoplasty. In human and animal cadaver experiments and live sheep, it was possible to use the RAMF for innervated intrathoracic use. The RAMF was stimulated by a specially designed car diomyostimulator (Medtronic Inc., Maastricht, The Netherlands). The flap might be promising as an addition to the currently available dynamic cardiomyoplastic techniques.