bluuebunny/crossref_metadata_2025 huggingface dataset:
Mammalian development in a changing environment: exposure to endocrine disruptors reveals the developmental plasticity of steroid‐hormone target organs
Authors: Markey Caroline M. , Coombs Macall A. , Sonnenschein Carlos , Soto Ana M.
Published: March 2003

SUMMARY Recent findings in the field of environmental endocrine disruption have revealed that developmental exposure to estrogenic chemicals induces morphological, functional, and behavioral anomalies associated with reproduction. The aim of the present study was to determine the effects of in utero exposure to low doses of the estrogenic chemical bisphenol A (BPA) on the development of the female reproductive tissues and mammary glands in CD‐1 mice. Humans are exposed to BPA, which leaches from dental materials and plastic food and beverage containers. Here we report that prenatal exposure to BPA induces alterations in tissue organization within the ovaries and mammary glands and disrupts estrous cyclicity in adulthood. Because estrogen receptors are expressed developmentally in these estrogen‐target organs, we propose that BPA may directly affect the expression of genes involved in their morphogenesis. In addition, alterations in the sexual differentiation of the brain, and thus the hypothalamic‐pituitary‐gonadal axis, may further contribute to the observed phenotype. The emerging field of endocrine disruptors promises to provide new insights into the mechanisms underlying the development of hormone‐target organs and demonstrates that the environment plays important roles in the making of phenotypes.
Critical weight in the development of insect body size
Authors: Davidowitz Goggy , D'Amico Louis J. , Nijhout H. Frederik
Published: March 2003

SUMMARY Body size is one of the most important life history characters of organisms, yet little is known of the physiological mechanisms that regulate either body size or variation in body size. Here, we examined one of these mechanisms, the critical weight, which is defined as the minimal mass at which further growth is not necessary for a normal time course to pupation. The critical weight occurred at 55% of peak larval mass in laboratory‐reared larvae of the tobacco hornworm Manduca sexta. We examined the effects of genetic and environmental variation in the critical weight on body size. As in many other insects, Manduca larvae reared on poor diets were smaller and those reared at lower temperatures were larger than control animals. We demonstrated that the critical weight was lower on low quality diets but did not change with temperature. There was significant genetic variation for body size, for plasticity of body size, and for critical weight, but not for plasticity of critical weight. Variation in the critical weight accounted for 73% of between‐family variance in peak larval size, whereas plasticity of critical weight was not significantly correlated with plasticity of body size. Our results suggest that although critical weight is an important factor in determining body size and enabling the evolution of body size, it may, at the same time, act as a constraint on the evolution of plasticity of body size. Thus, the determinants of body size and the determinants of plasticity of body size do not need to be identical.
The Analysis of Driving Mode Influence on Energy Dissipation in Pneumatic Artificial Heart Chambers
Authors: Nawrat  , Malota
Published: March 2003

The energy dissipated in blood or on a total artificial heart (TAH) chamber's elements directly or indirectly decreases the biological or technical safety of the TAH's work. The energetic analysis of the Polish total artificial heart (POLTAH) external work with the objective of estimating the valve and membrane roles in energy dissipation has been performed. The simulation of left and right artificial heart chamber work under physiological conditions using a self‐constructed physical model of the circulatory system has been performed for the full systole percent and frequency range and for different valves. The total energy dissipated on valves equals 15–30% of the chambers' work value. Energy losses on valves are influenced by the driving mode. The usage of inappropriate systolic and diastolic times increases the value of the energy dissipated on the membrane and on valves in the overall energy balance. The absolute value of the energy dissipated on the valves increases with the increase of the cycle time and depends on the valve type. The energy dissipated on the outlet valve decreases with the frequency (if the remaining driving parameters are kept constant) and for 150 bpm is nearly 3 times lower than that for 30 bpm. The energy dissipated on the membrane equals 10–50% of the TAH's work during systole, depending on the driving parameters. The filling process is assisted by the pressure from the atrium, and a great amount of energy during the diastolic period is consumed by the start of the membrane movement. We have also estimated the influence of the driving parameters on the valves' functions, measuring the acoustic wave intensity. The conclusions drawn are of a general character; they are applicable to all membrane, pneumatically powered blood pumps.
Ethics of the Allocation of Highly Advanced Medical Technologies
Authors: Sass Hans‐Martin
Published: March 2003

The disproportionate distribution of financial, educational, social, and medical resources between some rich countries of the northern hemisphere and less fortunate societies creates a moral challenge of global dimension. The development of new forms of highly advanced medical technologies, including neoorgans and xenografts, as well as the promotion of health literacy and predictive and preventive medical services might reduce some problems in allocational justice. Most governments and the World Health Organization (WHO) reject financial and other rewards for living organ donors thus indirectly contributing to the development of black markets. A societal gratuity model supporting and safeguarding a highly regulated market between providers and recipients of organs might provide for better protection of those who provide organs not solely based on altruistic reasons. The moral assessment of global issues in allocation and justice in the distribution of medical technologies must be increased and will have to be based on the principles of self determination and responsibility, solidarity and subsidiarity, and respect for individual values and cultural traditions.
The Effects of a Polyacrylonitrile Membrane and a Membrane Made of Regenerated Cellulose on the Plasma Concentrations of Erythropoietin During Hemodialysis
Authors: Opatrný Jr Karel , Kroužecký Aleš , Wirth Jan , Vít Ladislav , Eiselt Jaromír
Published: March 2003

In vitro studies have shown that some dialysis membranes significantly adsorb erythropoietin (EPO), a fact that might have an effect on anemia in long‐term hemodialysis (HD) patients and on anemia treatment with recombinant human EPO. The purpose of the study was to determine whether the ability of adsorption demonstrated in vitro also has an effect on EPO concentrations in vivo. In a crossover study, the plasma concentrations of EPO were examined in 11 patients on chronic HD during HD using a polyacrylonitrile (AN69) membrane (high in vitro adsorption) plus EPO administered subcutaneously after the HD session, HD using a Cuprophan membrane (low in vitro adsorption) plus EPO administered subcutaneously after the HD session, HD using an AN69 membrane plus EPO administered subcutaneously after the HD session plus EPO administered intravenously immediately before HD, or HD using a Cuprophan membrane plus EPO administered subcutaneously after the HD session plus EPO intravenously immediately before HD. The intradialysis plasma concentrations of EPO (not detectable in the dialysate) determined at the dialyzer inlet and outlet at Minutes 5 and 240 of the procedure did not differ significantly after its subcutaneous administration from its predialysis concentrations with either the Cuprophan or AN69 membrane. A comparison of EPO concentrations between AN69 and Cuprophan did not reveal marked differences either. The course of concentrations after additional EPO intravenous administration was similar with no statistically demonstrable difference between the 2 membranes. In conclusion, under clinical conditions, AN69 and Cuprophan membranes do not differ in their effects on plasma EPO concentrations. The differences in EPO adsorption between AN69 and Cuprophan, demonstrated in vitro, do not seem to be of clinical importance.
Cytokine Release During Long‐Term Extracorporeal Circulation in an Experimental Model
Authors: Adrian Katrin , Mellgren Karin , Skogby Maria , Friberg Lars Göran , Mellgren Gösta , Wadenvik Hans
Published: March 2003

The objective of this study was to determine the degree of leukocyte activation, as measured by cytokine release, in circulating blood during experimental extracorporeal circulation. Complete in vitro extracorporeal membrane oxygenation (ECMO) circuits were used, and 9 experiments were performed. Whole blood stored at 37°C was used as the control. Blood samples were withdrawn before the start of perfusion and at 24 h of perfusion. Statistically significant releases of interleukin (IL)‐1β, IL‐8, and IL‐1 receptor antagonist were observed in the perfusion circuits compared to both the control blood and baseline values. Also, increases in plasma tumor necrosis factor (TNF)α and IL‐6 were seen after 24 h of perfusion although these changes did not reach statistical significance. These results indicate that extracorporeal circulation induced leukocyte activation and cytokine release. These reactions might, as an additional trauma, deteriorate the situation in an already severely ill patient. A search for methods to counteract this untoward activation seems warranted.
Study of Left Ventricular Bypass Using Wankel Type Semipulsatile Blood Pump
Authors: Mitsui Norimasa , Fukunaga Shintaro , Sueda Taijiro , Matsuura Yuichiro , Havlik Patrick , Trinkl Jean , Demunck Jean‐Luc , Mesana Thierry , Montiès Jean‐Raoul
Published: March 2003

Abstract The influence of the Wankel type semipulsatile left ventricular assistance on hemodynamics was investigated with a computer simulation and an animal experiment. A simulation circuit was constructed to express the circulatory system. A current source was added to create a semipulsatile blood pump. The left and right ventricles were replaced by variable compliances. Left heart failure was simulated by decreasing the amount of compliance change of the left ventricle. Under the condition of heart failure when semipulsatile assist flow increased, the mean aortic pressure (AoP), tension time index (TTI), and diastolic pressure time index (DPTI) increased, and the cardiac output, pulse pressure (PP), and pulsatility indicator (PI) decreased. In an animal experiment, a Wankel type blood pump was used in a calf. With the increase of the assist flow, AoP curves became less pulsatile, and PP and PI decreased in accordance, which was predicted by the numerical simulation.
In Vitro Performance of a Centrifugal, a Mixed Flow, and an Axial Flow Blood Pump
Authors: Araki Kenji , Anai Hirofumi , Oshikawa Mitsuo , Nakamura Kunihide , Onitsuka Toshio
Published: March 2003

Abstract We specially devised 3 types of turbo pumps, a centrifugal pump (CFP), a mixed flow pump (MFP), and an axial flow pump (AFP), and analyzed their in vitro performance. The common structural design elements were an impeller diameter of 20 mm and sealless magnet couple driving. In vitro tests were carried out using heparinized fresh bovine blood. The hemolysis was comprehensively evaluated at 7–16 points by changing the flow rate and pressure head (mapping of hemolytic property). The maximum efficiency (motor output to pump output) was 44.9% at 7,000 rpm, 3.17 L/min, 191 mm Hg in the CFP; 66.3% at 7,000 rpm, 6.9 L/min, 136 mm Hg in the MFP; and 20.6% at 9,000 rpm, 5.54 L/min, 74 mm Hg in the AFP, respectively. The minimum normalized index of hemolysis (NIH) (g/100 L) was 0.038 at 5,000 rpm, 4.60 L/min, 38 mm Hg in the CFP; 0.010 at 7,000 rpm, 8.22 L/min, 100 mm Hg in the MFP; and 0.033 at 7,000 rpm, 2.84 L/min, 48 mm Hg in the AFP, respectively. The best efficiency and NIH were achieved in the MFP.
Safety of Beating Heart Anastomosis During Video‐Assisted Coronary Surgery Attested by Cardiac Troponin I
Authors: Babatasi Gérard , Massetti Massimo , Nataf Patrick , Fradin Sabine , Khayat André
Published: March 2003

Our objective was to evaluate the safety of coronary anastomosis on the beating heart by measuring the release of cardiac troponin I during minimally invasive coronary artery bypass grafting (MICABG). Cardiac troponin I (cTnI) is a reliable marker of cardiac ischemia during heart operations under cardiopulmonary bypass (CPB). Ten patients (8 males and 2 females, aged 41–63) underwent MICABG with single vessel bypass grafting for left anterior descending coronary artery (LAD) stenosis (n = 7) or occlusion (n = 3). Video‐assisted surgery with left anterior minithoracotomy was performed in all patients. Serial venous blood samples were collected for measurement of cTnI before LAD occlusion (T0), during anastomosis (T1) and 10 min (T2), 6 h (T3), 24 h (T4), 48 h (T5), and 72 h (T6) after coronary reperfusion. The assay method used a specific enzyme‐linked immunosorbent Stratus autoanalyzer. Control coronary angiography was performed in all patients. There were no operative complications or reoperations for bleeding. The cTnI concentrations were expressed in ng/ml ± SD. The mean cTnI level was less than 3.05 ± 0.2 ng/ml (range 0–32.8). Values were T0 = 0, T1 = 0.4 ± 0.03, T2 = 1.15 ± 0.2, T3 = 2.16 ± 0.6, T4 = 1.5 ± 0.3, T5 = 0.6 ± 0.02, and T6 = 0.4 ± 0.01. Angiography showed patent grafts in 9 patients. In one case, early internal thoracic artery (ITA) graft occlusion in a patient with 2 vessel disease was correlated with a higher cTnI concentration (17.8 ng/ml). Percutaneous angioplasty was performed on the right coronary artery, complicated with dissection and cardiac failure. This patient died 3 months after the MICABG despite support from a ventricular assist device. In conclusion, collateral circulation developed in the setting of chronic coronary occlusion may be efficient for myocardial preservation during short periods such as coronary anastomosis. cTnI immunoassay confirmed the safety of coronary anastomosis on the beating heart during minimally invasive coronary operations.
An Implantable Centrifugal Blood Pump with a Recirculating Purge System (Cool‐Seal System)
Authors: Yamazaki Kenji , Litwak Philip , Tagusari Osamu , Mori Toshio , Kono Kunihisa , Kameneva Marina , Watach Mary , Gordon Lisa , Miyagishima Masayuki , Tomioka Jun , Umezu Mitsuo , Outa Eisuke , Antaki James F. , Kormos Robert L. , Koyanagi Hitoshi , Griffith Bartley P.
Published: March 2003

A compact centrifugal blood pump has been developed as an implantable left ventricular assist system. The impeller diameter is 40 mm, and pump dimensions are 55 × 64 mm. This first prototype, fabricated from titanium alloy, resulted in a pump weight of 400 g including a brushless DC motor. The weight of a second prototype pump was reduced to 280 g. The entire blood contacting surface is coated with diamond like carbon (DLC) to improve blood compatibility. Flow rates of over 7 L/min against 100 mm Hg pressure at 2,500 rpm with 9 W total power consumption have been measured. A newly designed mechanical seal with a recirculating purge system (Cool‐Seal) is used for the shaft seal. In this seal system, the seal temperature is kept under 40°C to prevent heat denaturation of blood proteins. Purge fluid also cools the pump motor coil and journal bearing. Purge fluid is continuously purified and sterilized by an ultrafiltration unit which is incorporated in the paracorporeal drive console. In vitro experiments with bovine blood demonstrated an acceptably low hemolysis rate (normalized index of hemolysis = 0.005 ± 0.002 g/100 L). In vivo experiments are currently ongoing using calves. Via left thoracotomy, left ventricular (LV) apex descending aorta bypass was performed utilizing an expanded polytetrafluoroethylene (ePTFE) vascular graft with the pump placed in the left thoracic cavity. In 2 in vivo experiments, the pump flow rate was maintained at 5–9 L/min, and pump power consumption remained stable at 9–10 W. All plasma free Hb levels were measured at less than 15 mg/dl. The seal system has demonstrated good seal capability with negligible purge fluid consumption (<0.5 ml/day). In both calves, the pumps demonstrated trouble free continuous function over 6 month (200 days and 222 days).
Total Blood Exchange Suppresses the Early Stage of Liver Regeneration Following Partial Hepatectomy in Rats
Authors: Eguchi Susumu , Sugiyama Nozomu , Kawazoe Yasushi , Kawashita Yujo , Fujioka Hikaru , Furui Junichiro , Kanematsu Takashi
Published: March 2003

Despite its obscure and short effect, plasma exchange (PE) remains a mainstay in the treatment of liver disease. However, the question still remains as to whether or not PE suppresses the regeneration of the liver because PE deprives patients of hepatotrophic factors. The effect of PE, which could be a total blood exchange (TBE) in a syngeneic setting, on liver regeneration following a 68% partial hepatectomy (PH) was investigated in rats. In Group 1, 20 ml of blood from normal rats was infused while native blood was removed at 6 and 12 h after PH. In Group 2, 20 ml of blood obtained from PH rats at the same time points was infused. The regeneration rate, labeling index of proliferating cell nuclear antigen (PCNA), and plasma hepatocyte growth factor (HGF) level were determined, and standard liver function tests performed at 24, 48, and 72 h. Although all liver function tests improved in Group 1 at 24 and 48 h, the regeneration rate was significantly impaired. Similarly, the PCNA labeling index was significantly lower in Group 1 than that in Group 2. The plasma HGF level was significantly reduced in Group 1 (6 h blood out versus blood in: 1.1 ± 0.5 vs. 0.1 ± 0.1 ng/ml, p < 0.05). TBE with normal blood following PH suppressed the early stage of liver regeneration, in part, because of the reduction of HGF even though the blood was purified.
Aprotinin Reduces the Expression of P‐Selectin on the Surface of Platelet and Leukocyte‐Platelet Conjugates
Authors: Inui Kiyoshige , Shimazaki Yasuhisa , Watanabe Takao , Kuraoka Setsuo , Uesho Kunihiro , Uchida Tetsuro , Shiono Satoshi
Published: March 2003

P‐Selectin, an adhesion molecule expressed on the surfaces of activated platelets and the vascular endothelium, mediates platelet binding to monocytes and neutrophils. Monocytes and neutrophils produce superoxide anion by activated platelets through p‐selectin. Aprotinin, a serine protease inhibitor, inhibits plasmin to activate platelets during cardiopulmonary bypass (CPB). A total of 25 patients were studied to clarify the effects of aprotinin on p‐selectin expression during CPB. Nine patients were not given aprotinin (control group), and 16 were given aprotinin of 2 million U in the priming solution (aprotinin group). The platelet count and soluble p‐selectin in the plasma, p‐selectin on the surface membranes of platelets, and leukocyte‐platelet conjugate levels were measured during and after CPB. The platelet count was maintained well in the aprotinin group. The increases of soluble p‐selectin in the plasma, platelet surface p‐selectin, and leukocyte‐platelet conjugates were less in the aprotinin group than in the control group (p < 0.05). In conclusion, aprotinin in patients undergoing CPB may reduce the early inflammatory reactions induced by p‐selectin.
Heparin Coating Extends the Durability of Oxygenators Used for Cardiopulmonary Support
Authors: Usui Akihiko , Hiroura Manabu , Kawamura Mitsuo
Published: March 2003

Abstract: A comparative study was performed between a noncoated and heparin‐coated cardiopulmonary support (CPS) systems with the same design and structure (Terumo Corporation, Capiox‐SX series) to evaluate whether or not heparin coating extends oxygenator service life. Fifty patients underwent CPS from January 1993 until December 1997, and 54 oxygenators (Capiox‐SX series) were used. There were 35 noncoated oxygenators (Group NC) and 19 heparin‐coated ones (Group HC). Significant predictors for the durability of oxygenators were evaluated by a nonparametric survival analysis and a proportional hazards regression analysis. Thirteen of 35 Capiox‐SX and only 2 of 19 Capiox SX‐HP revealed gas transfer failure and had to be exchanged. The average life span of the Capiox‐SX and Capiox‐SX‐HP were calculated to be 78.6 ± 16.8 and 168 ± 15.4 h, respectively. Group HP showed significantly longer durability than Group NC (p = 0.0017), although there were differences of perfusion index and platelet counts between the 2 groups. Heparin coating of the CPS system remained one of the 2 significant predictors (hazards ratio 8.871, p = 0.0449) to determine the durability of oxygenators by increasing stepwise multivariate proportional hazards regression analysis, along with anemia with less than 8 g/dl hemoglobin (hazards ratio 9.438, p = 0.0173). Heparin coating of the CPS system assures improved durability because heparin‐coated oxygenators have a longer service life than noncoated ones.
Clinical Application of the M‐Numbers of Aortic Cannulas During Hypothermic Cardiopulmonary Bypass in Pediatric Patients
Authors: Kim Won Gon , Park Seong‐Sik
Published: March 2003

A standardized system to describe the pressure‐flow characteristics of a given cannula has recently been proposed and has been termed the M‐number system. Using 3 different sizes of aortic cannulas in 50 pediatric cardiac patients on hypothermic cardiopulmonary bypass, we analyzed the correlation between experimentally and clinically derived M‐numbers and found it to be positive. Clinical M‐numbers were typically 0.35 to 0.55 greater than experimental M‐numbers and correlated inversely with a patient's temperature change; this was most probably due to increased blood viscosity arising from hypothermia. This inverse relationship was more marked in higher M‐number cannulas. The clinical data obtained in this study suggest that the experimentally derived M‐number correlates strongly with the clinical performance of the cannula and that the influence of temperature is significant.
Defining the Microbiological Quality of Dialysis Fluid
Authors: Ledebo Ingrid , Nystrand Rolf
Published: March 2003

With increasing awareness about the degree and the potential impact of microbiological contamination in dialysis fluids, there is a desire to improve their microbiological quality. To achieve this goal, the origin of the microbiological contamination has to be identified. The water, the bicarbonate concentrate, and the fluid distribution system can be major contributors. Regular disinfection of the entire fluid path is necessary to prevent the formation of biofilm. The bicarbonate concentrate should be handled with special attention because it constitutes an excellent growth medium for microflora that may not be detected with regular assays. With a well maintained reverse osmosis (RO) system, frequent disinfection of the entire flow path, and microbiological awareness, it is possible to produce dialysis fluid that meets the most stringent standard (<102 colony forming units (CFU)/ml and <0.25 IU/ml of endotoxin). Adding a step of ultrafiltration just before the dialyzer can make the dialysis fluid ultrapure (<10−1 CFU/ml and <0.03 IU/ml). One additional step of controlled ultrafiltration provides sterile and pyrogen‐free fluids (<10−6 CFU/ml and <0.03 IU/ml) that can be used for infusion.
Methods for Quantitative Analysis of the Primary Stability in Uncemented Hip Prostheses
Authors: Monti Luisa , Cristofolini Luca , Viceconti Marco
Published: March 2003

Abstract: Torsional loads of daily activities contribute to the failure of the primary fixation of hip prostheses. Implant torsional stability must be evaluated prior to in vivo clinical trials. Whereas previous work has investigated this phenomenon, descriptions of physiologically accurate and reproducible in vitro methodologies are rare. The present study aimed to detect and control the sources of error and variability that influence in vitro methods. A typical set‐up for the analysis of primary stability of hip stems was studied. Load cycles included proximal‐to‐distal axial force, torque, and bending moment. The effects of loading frequency and strain distribution across the cortical bone were investigated in order to optimize testing conditions and measurement set‐up. The relative shear motion at the bone‐stem interface was measured transcortically using linear variable displacement transducers. The procedures developed for mounting specimens on the testing machine and for positioning sensors on the specimen were standardized and tested for reproducibility. The protocol was finally tested for repeatability and accuracy. Measurement errors were 2.3 μm between load cycles and 4.9 μm for repeated set‐ups, comparing favorably with the literature.
In Vivo Evaluation of the National Cardiovascular Center Electrohydraulic Total Artificial Heart
Authors: Tatsumi Eisuke , Masuzawa Toru , Nakamura Makoto , Taenaka Yoshiyuki , Nishimura Takashi , Endo Seiko , Zhang Bin , Kakuta Yukihide , Nakata Masako , Nakamura Tomomichi , Nishinaka Tomohiro , Takano Hisateru , Tsukahara Kinji , Tsuchimoto Katsuya
Published: March 2003

We have been developing an electrohydraulic total artificial heart system. The system comprises an intrathoracic pumping unit composed of diaphragm type ellipsoidal blood pumps and an energy converter in addition to an electronics unit. The in vivo performance of the pumping unit was evaluated in a series of animal implantations with 3 calves weighing 62–85 kg. An interatrial shunt 4.5 mm in diameter was made in the atrial septum to compensate left‐right imbalance. Two calves died early postoperatively, one of external controller power failure and the other of interatrial shunt stenosis due to thrombus formation. One calf, however, survived over 10 days under stable circulatory conditions. No abnormality was found in the oxygen metabolic condition or in major organ functions. The generation and dissipation of heat from the device was acceptable. This animal died of device malfunction caused by energy converter bearing breakdown. The device demonstrated a good anatomic fit without compromising the great vessels and adjacent tissues. It is concluded that the pumping unit has a sufficient in vivo basic performance although appropriate countermeasures are to be implemented against the detected problems concerning mechanical durability and interatrial shunt patency.
Major Organ Function Under Mechanical Support: Comparative Studies of Pulsatile and Nonpulsatile Circulation
Authors: Sezai Akira , Shiono Motomi , Orime Yukihiko , Nakata Kin‐ichi , Hata Mitsumasa , Iida Mitsuru , Kashiwazaki Satoshi , Kinoshita Jun‐ichi , Nemoto Mitsuhiro , Koujima Takashi , Furuichi Motohiko , Eda Kunihiro , Hirose Hiroyuki , Yoshino Takanori , Saitoh Akira , Taniguchi Yoshiki , Sezai Yukiyasu
Published: March 2003

We examined a major organ function during 3 h biventricular assisted circulation after acute myocardial infarction model in the pig. In left ventricular circulation, the outflow cannula was placed in the ascending aorta and an inflow cannula through the mitral valve in the left ventricle. A pump (pulsatile group, Zeon Medical, Inc., Tokyo, Japan and nonpulsatile group, Nikkiso HPM‐15, Nikkiso, Inc., Tokyo, Japan) was connected to each cannula. In right ventricular circulation, the outflow cannula was placed in the pulmonary artery and an inflow canula in the right ventricle. The right ventricular circulation was supported by a nonpulsatile pump (Nikkiso HPM‐15). The items measured were the regional blood flows of the cortex and medulla in the kidney, white matter and gray matter in brain, and liver; renal arterial flow; carotid arterial flow; portal vein flow; common hepatic arterial flow; arterial ketone body ratio (AKBR); and lactate/pyrubic acid (L/P). In the pulsatile group, the renal cortical blood flow increased, and the medulla blood flow decreased. On the other hand, in the nonpulsatile group, both regional blood flows decreased. That means that in the pulsatile assisted group intrarenal redistribution improved rather than in the nonpulsatile assisted group. In addition the liver regional blood flow, AKBR, and L/P showed significant differences between the pulsatile and nonpulsatile groups. On the other hand, the white matter and gray matter regional blood flows and carotid arterial flow did not show significant differences between the groups. The results of our study indicated that pulsatile circulation produced superior circulation in the kidney and liver, and microcirculation on the cell level was superior as well in early treatment of acute heart failure.
Battery‐Powered Implantable Nerve Stimulator for Chronic Activation of Two Skeletal Muscles Using Multichannel Techniques
Authors: Lanmüller Hermann , Sauermann Stefan , Unger Ewald , Schnetz Guntram , Mayr Winfried , Bijak Manfred , Rafolt Dietmar , Girsch Werner
Published: March 2003

Chronic activation of skeletal muscle is used clinically in representative numbers for diaphragm pacing to restore breathing and for dynamic graciloplasty to achieve fecal continence. The 3 different stimulation techniques currently used for electrophrenic respiration (EPR) all apply high frequency powered implants. It was our goal to make these stimulation methods applicable for EPR by a battery‐powered nerve stimulator that would maximize the patient's freedom of movement. Additionally, the system should allow the implementation of multichannel techniques and alternating stimulation of 2 skeletal muscles as a further improvement in graciloplasty. Generally, the developed implantable nerve stimulator can be used for simultaneous and alternating activation of 2 skeletal muscles. Stimulation of the motor nerve is achieved by either single channel or multichannel methods. Carousel stimulation and sequential stimulation can be used for graciloplasty as well as for EPR. For EPR we calculated an operating time of the implant battery of 4.1 years based on the clinically used stimulation parameters with carousel stimulation. The multichannel pulse generator is hermetically sealed in a titanium case sized 65 × 17 mm (diameter × height) and weighs 88 g.
Long Pulse Biphasic Electrical Stimulation of Denervated Muscle
Authors: Woodcock Alan H. , Taylor Paul N. , Ewins David J.
Published: March 2003

In recent years a number of studies have employed long pulse biphasic stimulation as a treatment for denervated muscle to improve tissue quality and in some cases to improve contractile capability sufficient to restore function. However, in the U.K., this treatment is yet to be widely adopted clinically. A 5 subject, case based pilot study of long pulse biphasic direct stimulation of peripheral limb denervated muscle is being conducted and its effect on the tissue evaluated by measurement of muscle bulk, limb blood flow, and skin temperature. In cases of partial denervation, trapezoidal shaped pulses are used to minimize sensory and motor nerve fiber recruitment.
Experience with Emergency Cardiac Surgery Following Institution of Percutaneous Cardiopulmonary Support
Authors: Mitsui Norimasa , Koyama Tadaaki , Marui Akira , Mochizuki Takaaki , Hayashi Yasuhiko
Published: March 2003

Between August 1992 and February 1998, 43 patients were treated with percutaneous cardiopulmonary support (PCPS) in our institution, and 8 of them subsequently required emergency cardiac surgery. There were 3 males and 5 females with a mean age of 63 years (range, 37 to 81 years). The etiology of shock in these 8 patients was acute myocardial infarction in 3, postinfarction left ventricular (LV) free wall rupture in 1, postinfarction ventricular septal perforation (VSP) in 1, LV free wall rupture and VSP in 1, and fatal arrhythmia due to severe aortic valvular disease in 2. The mean time interval from the onset of cardiogenic shock to the institution of PCPS was 77 min (range, 18 to 183 min). The mean time interval from the institution of PCPS until surgery was 145 min (range, 40 to 603 min). The surgical procedures were coronary artery bypass grafting (CABG) in 3 patients, closure of the LV rupture and/or closure of VSP in 3, and aortic valve replacement in 2. Six patients were weaned from PCPS, and 2 patients were discharged from the hospital (discharge rate, 25%). Although the results of emergency cardiac surgery following PCPS still are not satisfactory, we continue to apply PCPS and perform appropriate surgical procedures to improve the survival rate of the patients who would die without PCPS.
Development of the Valvo Pump: An Axial Flow Pump Implanted at the Heart Valve Position
Authors: Mitamura Yoshinori , Nakamura Hiroki , Okamoto Eiji , Yozu Ryohei , Kawada Shiaki , Kim Dong‐Wook
Published: March 2003

Pulsatile artificial hearts having a relatively large volume are difficult to implant in a small patient, but rotary blood pumps can be easily implanted. The objective of this study was to show the feasibility of using the Valvo pump, an axial flow pump implanted at the heart valve position, in such cases. The Valvo pump consists of an impeller and a motor. The motor is waterproofed with a ferrofluidic seal. A blood flow of 5 L/min was obtained at a pressure difference of 13.3 kPa (100 mm Hg) at 7,000 rpm. The normalized index of hemolysis (NIH) was 0.030 ± 0.003 (n = 3) for a blood flow of 5 L/min at a pressure difference of 13.3 kPa. The pressure resistance of the ferrofluidic seal was 37.5 kPa in a static condition and 26.3 kPa at 10,000 rpm. The seal exhibited no leaks for 41+ days against 20.0 kPa. The results showed that the Valvo pump can maintain systemic circulation with an acceptable level of hemolysis.
An Emergency Balloon Occlusion System for a Rotary Blood Pump Left Ventricular Assist System
Authors: Ohtsuka Goro , Yoshikawa Masaharu , Sueoka Akinori , Saito Koshiro , Igarashi Akira , Tayama Eiki , Nakata Kin‐ichi , Takano Tamaki , Glueck Julia , Koyanagi Hitoshi , Nosé Yukihiko
Published: March 2003

A fatal outcome is expected in a left ventricular assist system (LVAS) utilizing a rotary blood pump if there is no mechanism to prevent the backflow from the aorta to the heart in the case of acute pump failure. To solve this problem, a passive mechanical clamping system at the outflow graft of a rotary blood pump was developed together with Fuji Systems, Inc., Yokohama, Japan. The system consisted of an emergency clamp port and an occlusion balloon. The balloon was fixed around the outlet graft of the LVAS. In an in vitro study, a fail‐safe clamping operation with 2 ml saline injection under 7 L/min flow against 140 mm Hg pressure reduced the flow to 0.5 L/min while the pressure in the system increased to 190 mm Hg. The systems were also applied to 2 in vivo LVAD studies. When the pumps were stopped, there were approximately 3.0 L/min regurgitant flows. The balloon occluder prevented this regurgitant flow effectively against a 100/80 mm Hg arterial pressure. In conclusion, this emergency balloon occlusion system is relatively easy to operate and will work efficiently in all possible clinically encountered malfunctions of the rotary blood pump LVAS.
Augmentative Effect of Pulsatility on the Wall Shear Stress in Tube Flow
Authors: Nakata Masako , Tatsumi Eisuke , Tsukiya Tomonori , Taenaka Yoshiyuki , Nishimura Takashi , Nishinaka Tomohiro , Takano Hisateru , Masuzawa Toru , Ohba Kenkichi
Published: March 2003

Wall shear stress (WSS) has been considered to play an important role in the physiological and metabolic functions of the vascular endothelial cells. We investigated the effects of the pulse rate and the maximum flow rate on the WSS to clarify the influence of pulsatility. Water was perfused in a 1/2 inch transparent straight cylinder with a nonpulsatile centrifugal pump and a pulsatile pneumatic ventricular assist device (VAD). In nonpulsatile flow (NF), the flow rate was changed 1 to 6 L/min by 1 L/min increments to obtain standard values of WSS at each flow rate. In pulsatile flow (PF), the pulse rate was controlled at 40, 60, and 80 bpm, and the maximum flow rate was varied from 3.3 to 12.0 L/min while the mean flow rate was kept at 3 L/min. The WSS was estimated from the velocity profile at measuring points using the laser illuminated fluorescence method. In NF, the WSS was 12.0 dyne/cm2 at 3 L/min and 33.0 dyne/cm2 at 6 L/min. In PF, the pulse rate change with the same mean, and the maximum flow rate did not affect WSS. On the other hand, the increase in the maximum flow rate at the constant mean flow rate of 3 L/min augmented the mean WSS from 13.1 to 32.9 dyne/cm2. We concluded that the maximum flow rate exerted a substantial augmentative effect on WSS, and the maximum flow rate was a dominant factor of pulsatility in this effect.
Extracorporeal Life Support in Pediatric Patients with Heart Failure
Authors: Marx Manfred , Salzer‐Muhar Ulrike , Wimmer Maria
Published: March 2003

Abstract: The prognosis of patients with end‐stage heart failure presenting with acute clinical deterioration is poor. Extracorporeal membrane oxygenation (ECMO), however, can provide univentricular and biventricular cardiac support which has led to the extended application of ECMO to infants and children. With improving results, indications and modalities of mechanical support have changed, and mechanical bridge to cardiac transplantation will offer extended survival for selected patients. The purpose of this article is to provide comprehensive data of pediatric cardiac support and to discuss the central role of echocardiography in the estimation of cardiac performance during mechanical support. As a conclusion, one can predict that the encouraging results of today will lead to further technological developments, which will create individual technical solutions of different clinical applications.
Pulmonary Failure After Norwood Procedure: Indication for Extracorporeal Membrane Oxygenation? A Case Report
Authors: Boigner Harald , Trittenwein Gerhard , Marx Manfred , Golej Johann
Published: March 2003

Abstract: Today some authors consider univentricular repair a contraindication for postoperative cardiac extracorporeal membrane oxygenation (ECMO). The question is whether or not ECMO is indicated as pulmonary support in case of an overwhelming pulmonary infection during the postoperative course after a Norwood procedure. During the prolonged weaning period after a Norwood procedure using a 4 mm aortopulmonary shunt, proven respiratory syncytial virus (RSV) bronchiolitis occurred at the time of expected weaning from artificial ventilation. Venovenous ECMO was able to improve oxygenation, but when pulmonary opacification failed to resolve, ECMO was terminated after 12 days.
The Cleaning and Disinfecting of Hemodialysis Equipment Using Electrolyzed Strong Acid Aqueous Solution
Authors: Tanaka  , Fujisawa  , Daimon  , Fujiwara  , Yamamoto  , Abe T.
Published: March 2003

In general, sodium hypochlorite, formalin, and Dialox (Teijin Gambro Medical, Ltd., Tokyo, Japan [main ingredients: H2O2, CH3CHOOOH, CH3COOH, H2O]) are used to clean and disinfect hemodialysis pipelines. In this study, the suitability of electrolyzed strong acid aqueous solution (ESAAS), which has attracted considerable interest in Japan because of its strong disinfecting properties, was examined. The crossover method was used to investigate the effectiveness of ESAAS in disinfecting the dialysis pipelines in comparison to that of sodium hypochlorite (200 ppm) used alternately with 1% acetic acid. The number of bacteria and the concentration of endotoxin (Et) were measured over an approximately 3 year period, starting in September 1994. Until then, 200 ppm sodium hypochlorite had been used alternately with 1% acetic acid, and the contamination of the pipeline had been marked. However, after switching to the ESAAS disinfection method, the dialysis pipelines very rapidly became cleaner. Therefore, the decision to develop an automated ESAAS cleaning system for long‐term use was made. During the development period, the original disinfectants (200 ppm sodium hypochlorite used alternately with 1% acetic acid) were used as a stopgap. After confirmation of its performance and safety, the automated ESAAS cleaning system was introduced. To find out whether the decrease in bacteria secondarily caused a decrease in the Et concentration or whether the ESAAS directly inactivated the Et, an in vitro experiment was carried out. Highly concentrated Et, which had been left in the reverse osmosis (RO) drainage pipeline, was used as a sample to investigate the effects of ESAAS on Et at various concentrations and temperatures and on the recovery test. The results showed that ESAAS directly inactivated Et. This paper reports the results of the crossover test. The results of parallel tests carried out over an approximately 4 year period have already been reported. No significant problems occurred in the dialysis. The automated ESAAS cleaning system that was developed proved to be more economical than the conventional disinfecting method.
Influence of Different Hemodialysis Membranes on Red Blood Cell Susceptibility to Oxidative Stress
Authors: Lucchi Leonardo , Bergamini Stefania , Botti Barbara , Rapanà Renato , Ciuffreda Angela , Ruggiero Pio , Ballestri Marco , Tomasi Aldo , Albertazzi Alberto
Published: March 2003

Abstract: Oxidative stress is crucial in red blood cell (RBC) damage induced by activated neutrophils in in vitro experiments. The aim of the study was to evaluate whether the bioincompatibility phenomena occurring during hemodialysis (HD) (where neutrophil activation with increased free radical production is well documented) may have detrimental effects on RBC. We evaluated RBC susceptibility to oxidative stress before and after HD in 15 patients using Cuprophan, cellulose triacetate, and polysulfone membrane. RBC were incubated with t‐butyl hydroperoxide as an oxidizing agent both in the presence and in the absence of the catalase inhibitor sodium azide. The level of malonaldehyde (MDA), a product of lipid peroxidation, was measured at 0, 5, 10, 15, and 30 min of incubation. When Cuprophan membrane was used, the MDA production was significantly higher after HD, indicating an increased susceptibility to oxidative stress in comparison to pre‐HD. The addition of sodium azide enhanced this phenomenon. Both cellulose triacetate and polysulfone membranes did not significantly influence RBC susceptibility to oxidative stress. Neither the level of RBC reduced glutathione nor the RBC glutathione redox ratio changed significantly during HD with any of the membranes used. The RBC susceptibility to oxidative stress was influenced in different ways according to the dialysis membrane used, being increased only when using the more bioincompatible membrane Cuprophan, where neutrophil activation with increased free radical production is well documented. The alterations found in this study might contribute to the reduced RBC longevity of HD patients where a bioincompatible membrane is used.
The Effect of Sandblasting Treatment on Endurance Properties of Titanium Alloy Hip Prostheses
Authors: Baleani Massimiliano , Viceconti Marco , Toni Aldo
Published: March 2003

Abstract: Sandblasting is a procedure of increasing surface roughness. This treatment is common in the orthopedic field. An increased roughness may affect the endurance limit of the material. This study investigates the effect on the endurance limit of the Ti6Al4V due to two different sandblasting treatments: fine sandblasting and coarse sandblasting. Twenty hip stems, 10 finely sandblasted and 10 coarsely sandblasted, were tested under sinusoidal fluctuating bending. The staircase method was used to estimate the endurance limit of the material. The results show an important reduction in the endurance properties up to 40% for the coarsely sandblasted specimens. The failures of the sandblasted specimens were not due to material defects. Rather, the decreased endurance strength of the sandblasted stems was caused by surface defects, which act as crack initiators. By modulating the roughness with an appropriate sandblasting treatment, it is possible to limit the reduction in the endurance limit of the alloy.
Membranes for Endotoxin Removal from Dialysate: Considerations on Feasibility of Commercial Ceramic Membranes
Authors: Bender Heiko , Pflänzel Anne , Saunders Nicola , Czermak Peter , Catapano Gerardo , Vienken Joerg
Published: March 2003

Abstract: As the quality of water in dialysis fluid varies considerably, dialysate is often contaminated by large amounts of bacteria and endotoxins. Membrane properties and operating pressures are acknowledged to give high‐flux dialysis with bicarbonate the bacteriological potential to favor passage of endotoxin fragments from the dialysate into the blood stream. Therefore, a sterile dialysate will have to become a standard. Ultrafiltration across hydrophobic synthetic membranes was shown to remove endotoxins (and their fragments) from dialysis water by the combined effect of filtration and adsorption. However, each module can be used for a limited time only. Ceramic membranes may represent an alternative to polymeric membranes for endotoxin removal. In this article, we tested the capacity of different commercial ceramic membranes with nominal molecular weight cut‐off down to 1,000 to retain endotoxins from Ps. aeruginosa. The tested membranes did not generally produce dialysate meeting the Association for the Advancement of Medical Instrumentation standard. When using aluminum‐containing membranes, we detected aluminum leaking into the dialysate that could possibly be transported into the blood stream.
Development of a Compact, Sealless, Tripod Supported, Magnetically Driven Centrifugal Blood Pump
Authors: Yuhki Akira , Nogawa Masamichi , Takatani Setsuo
Published: March 2003

Abstract: In this study, a tripod supported sealless centrifugal blood pump was designed and fabricated for implantable application using a specially designed DC brushless motor. The tripod structure consists of 3 ceramic balls mounted at the bottom surface of the impeller moving in a polyethylene groove incorporated at the bottom pump casing. The follower magnet inside the impeller is coupled to the driver magnet of the motor outside the bottom pump casing, thus allowing the impeller to slide‐rotate in the polyethylene groove as the motor turns. The pump driver has a weight of 230 g and a diameter of 60 mm. The acrylic pump housing has a weight of 220 g with the priming volume of 25 ml. At the pump rpm of 1,000 to 2,200, the generated head pressure ranged from 30 to 150 mm Hg with the maximum system efficiency being 12%. When the prototype pump was used in the pulsatile mock loop to assist the ventricle from its apex to the aorta, a strong correlation was obtained between the motor current and bypass flow waveforms. The waveform deformation index (WDI), defined as the ratio of the fundamental to the higher order harmonics of the motor current power spectral density, was computed to possibly detect the suction occurring inside the ventricle due to the prototype centrifugal pump. When the WDI was kept under the value of 0.20 by adjusting the motor rpm, it was successful in suppressing the suction due to the centrifugal pump in the ventricle. The prototype sealless, centrifugal pump together with the control method based on the motor current waveform analysis may offer an intermediate support of the failing left or right ventricle bridging to heart transplantation.