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PubMed2003

Rapid assessment of sedimentation stability in dispersions using near infrared transmission measurements during centrifugation and oscillatory rheology.

We used the LUMiFuge) 114 particle separation analyser to investigate the sedimentation kinetics of bentonite/xanthan gum mixtures through pH 2-7 during centrifugation. This new technique monitors timed near infrared transmission profiles of different samples in the centrifugal field. Statistical analysis of the data then identifies the formulations with minimal clarification tendency. All mixtures were characterised by rotational and oscillatory rheology. Various rheological parameters correlated with the LUMiFuge clarification data, most notably the relaxation exponent, n and loss tangent, tan delta. We devised a combined desirability function for the different mixtures, defining maximal desirability as the minimal values for the two oscillatory parameters. The results matched those of separation analysis in the centrifugal field.We conclude that the experimental design is suitable for selecting formulations with optimal sedimentation stability whether combined with LUMiFuge analysis or oscillatory measurements. The method can be used to screen formulations for optimal long-term stability test performance, with significant potential savings and minimal sedimentation risk after prolonged storage.

Centrifugation↗
PubMed1999

Comparison of the distribution of progenitor cells in G-CSF-mobilized peripheral blood and steady-state bone marrow after counterflow centrifugal elutriation.

Blood-derived progenitor cells obtained following mobilization with granulocyte colony-stimulating factor (MoPBSC) are increasingly being used as an alternative to bone marrow (BM) in allogeneic stem cell transplantation. The higher numbers of mature T lymphocytes in MoPBSC grafts may increase the risk of (chronic) graft-vs.-host disease. Counterflow centrifugal elutriation (CCE) is an effective method for T-cell depletion of BM grafts. The elutriation characteristics of steady-state BM and MoPBSC were compared using a CCE procedure in which fractions were obtained after small incremental increases in flow rate with constant centrifugal force. Counterflow centrifugal elutriation experiments with MoPBSC from six healthy volunteers showed that 54% of all cells collected were recovered in the < or = 15 mL/minute fractions, whereas experiments with mononuclear BM cells from five healthy volunteers resulted in recovery of 52% of collected cells from the > or = 19 mL/minute fractions. The peak concentrations of CD34+ cells were found in the same fraction (18 mL/minute), but more CD34+ cells from MoPBSC were recovered from the small (< or = 16 mL/minute) fractions (54% for MoPBSC, 26% for BM; p = 0.08). The small CD34+ cells from BM were more frequently lacking CD38 and human leucocyte antigen-DR expression than the small CD34+ cells from MoPBSC. Mature T-cells (CD3+) in BM and MoPBSC samples had similar CCE features, as did early (long-term culture initiating cells, high-proliferative potential colony-forming cells) and more mature (colony-forming units granulocyte/macrophage, BFU-e) hematopoietic progenitor cells. The results of this study suggest that T-cell depletion by CCE of MoPBSC as compared to BM products, may lead to a greater loss of CD34+ cells, but not of immature hematopoietic progenitor cells.

Adult↗
PubMed2000

Rapid detection of respiratory viruses by centrifugation enhanced cultures from children with acute lower respiratory tract infections.

BACKGROUND: Acute respiratory tract infection (ARI) is the major cause of morbidity and mortality in young children in developing countries. Information on viral aetiology in ARI in India is very limited. OBJECTIVE: The aim of the study was to define the role of viruses in acute lower respiratory tract infections (ALRTI) in children in India using centrifugation enhanced cultures followed by indirect immunofluorescence (IIF). STUDY DESIGN: Nasopharyngeal aspirates (NPAs) were collected from children from September 1995 to April 1997, attending paediatric clinic of All India Institute of Medical Sciences (AIIMS) with symptoms of ALRTI. Virus isolation was done by centrifugation enhanced cultures using HEp-2, LLC-MK2 and MDCK cells. The viruses were identified at 24-48 h post inoculation by IIF staining using monoclonal antibodies to respiratory syncytial virus (RSV), parainfluenza virus (PIV), influenza virus and adenovirus. RESULTS: Of 200 NPA samples, 89 (44.5%) were positive for one or more viral pathogens. RSV was detected in 34 (17%) of all ALRTI cases followed by influenza viruses in 29 (14.5%), PIVs in 23 (11.5%) and adenoviruses in three (1.5%). In 79 children with bronchiolitis, RSV was most frequently isolated (25%) pathogen, while in bronchopneumonia cases (101) the most common viral pathogen was influenza virus (17%). In eight cases (4%) of ALRTI dual infections were detected. In 100 NPA specimens IIF staining on direct cell smears was carried out and viruses were detected in only 17%. RSV and influenza virus infection peaked from September to December, where as PIV infections were more frequent from January to April. CONCLUSION: Respiratory viruses accounted for 44.5% of cases of ALRTI in India and the results of viral aetiology could be given in 24-48 h using centrifugation enhanced cultures. RSV was the most common viral agent associated with ALRTI in children under 5 years of age with greater association with bronchiolitis.

Adenoviruses, Human↗
PubMed1997

A new method for the purification of human motile spermatozoa applying density-gradient centrifugation: polysucrose media compared to Percoll media.

PURPOSE: A newly developed method for the isolation of human motile spermatozoa using density-gradient centrifugation was compared with the traditionally used Percoll technique. METHOD: Sperm samples were divided into two equal aliquots, which were purified with either the traditionally performed Percoll technique or a new alternative based on polysucrose/Optiprep media. For each sample the isolation was performed during the same run of the centrifuge. RESULTS: The average recovery of progressively motile spermatozoa with the polysucrose/Optiprep method was significantly higher (48 +/- 7%) than with the Percoll method (38 +/- 6%) (n = 18). The average percentage of motile spermatozoa and the motility score were similar in the purified preparations. CONCLUSIONS: The new polysucrose/Optiprep-based density-gradient centrifugation technique for the isolation of motile human spermatozoa is as good as the traditionally used Percoll method and may replace it in connection with assisted reproduction techniques.

Cell Separation↗
PubMed2000

Application of a method incorporating differential centrifugation for selective isolation of motile actinomycetes in soil and plant litter.

The present paper describes a simple enrichment technique which enables rapid and selective isolation of diverse zoosporic actinomycete genera directly from soil and plant litter. This technique, designated the rehydration and centrifugation (RC) method, consists of immersing the air-dried source material in 10 mM phosphate buffer containing 10% soil extract, letting the preparation stand at 30 degrees C for 90 min, followed by centrifugation of the fluid at 1,500 x g for 20 min. Portions of the supernatant containing actinomycete zoospores are plated on the humic acid-vitamin agar which is supplemented with nalidixic acid and trimethoprim as the selective inhibitors for Gram-negative bacteria and bacilli. The phosphate buffer-soil extract solution significantly promoted liberation of motile zoospores from the source material. The centrifugation stage greatly eliminated streptomycetes and other non-motile actinomycetes from the liquid phase, thereby facilitating selective growth of rare, motile actinomycetes on the isolation plates subsequent to inoculation. Ten different soil and leaf-litter samples, taken from fields, forests, and stream banks, were examined. The RC method consistently achieved preferential isolation of motile actinomycetes in all samples, which accounted for 37-86% of the total microbial population recovered. The most frequently isolated motile actinomycetes were Actinoplanes and Dactylosporangium. Strains of Actinokineospora, Catenuloplanes and Kineosporia were also recovered, depending on the nature of the samples examined. Other motile actinomycetes that were occasionally isolated in small numbers included Actinosynnema, Geodermatophilus and Sporichthya.

Actinomycetales↗
PubMed2004

Centrifugal and electric field forces dual-pumping CD-like microfluidic platform for biomedical separation.

In this article, we propose a versatile CD-like multi-channel electrophoresis-based biomedical separation system that is driven by the interactive forces between the centrifugal force and the electric field force. The centrifugal force control of this system is realized through the velocity control of a DC servo motor, while the electric field is governed through the concentric conducting circuits, which are suitably designed and fabricated by sputtering on metal mask method, and can be adjusted to provide multi-stage voltages. Experimental results demonstrate that the electro-osmotic flow (EOF) effect can be effectively reduced when the electric field force and centrifugal force are in the opposite direction. Benefits from this are that the electrophoresis separation time can be prolonged and the length of the microfluidic channels can be shortened; therefore, more effective separation efficiency can be obtained. Moreover, other advantages, such as lower joule-heat generation, low-chemistry reaction, and no variation on the ion concentration during processes, make this biomedical separation system more useful.

Biopolymers↗
PubMed2004

Reduced senescence and retained nuclear DNA integrity in human spermatozoa prepared by density gradient centrifugation.

PURPOSE: To investigate whether removal of extraneous cells and immotile spermatozoa from a sperm preparation by density gradient centrifugation could help to maintain normal spermatozoa in a viable state and retain their deoxyribonucleic acid integrity. METHODS: Sperm motility was assessed on a daily basis in aliquots of neat semen, extended semen, and spermatozoa prepared on a PureSperm density gradient. At the same time, aliquots of each sperm sample were preserved for TUNEL assay and nick translation. RESULTS: Spermatozoa prepared using density gradient centrifugation survived three times as long as spermatozoa in neat semen or in extended semen. Both deoxyribonucleic acid integrity and sperm motility were retained in the gradient preparations. CONCLUSIONS: Preparing spermatozoa by density gradient centrifugation is advantageous in prolonging sperm survival and maintaining deoxyribonucleic acid integrity, presumably by removing sources of reactive oxygen species. Stored spermatozoa could be used for a second attempt at fertilization if oocyte immaturity was suspected.

Adult↗
PubMed1982

A comparison of counterflow centrifugation and unit gravity sedimentation in the separation of mouse bone marrow progenitor cells.

Both Unit Gravity Sedimentation and Counterflow Centrifugation separate cells primarily on the basis of size. However, when performed concurrently on the same normal mouse bone marrow cell suspensions, Unit Gravity Sedimentation was found to be far superior in terms of the recovery of total nucleated cell load and the recovery and enrichment of two classes of functional progenitors: (1) those responsive to the combined stimulus of pregnant mouse uterus extract (PMUE) plus human spleen conditioned medium (HUSPCM), and (2), those responsive to PMUE alone. Neither technique was able to resolve PMUE from PMUE + HUSPCM progenitors. The major limitation of Counterflow Centrifugation for the separation of sub-populations of marrow cells is related to the complexity and range of cell sizes in marrow cell suspensions which lead to significant pellet formation within the elutriator chamber. Furthermore, cells undergoing Counterflow Centrifugation are subjected to forces not encountered in Unit Gravity Sedimentation. Therefore, the basis of the separations is not identical and this is reflected in cell volume distributions of comparable fractions separated by each method.

Animals↗
PubMed1972

Subcellular fractionation by zonal centrifugation of glucose-repressed anaerobically grown Saccharomyces carlsbergensis.

1. Homogenates were prepared from sphaeroplasts of anaerobically grown, glucoserepressed Saccharomyces carlsbergensis, and the distributions of marker enzymes investigated after zonal centrifugation on sucrose gradients containing 2mm-MgCl(2). 2. These homogenates contained no detectable cytochrome c oxidase, succinate-cytochrome c oxidoreductase, succinate-ferricyanide oxidoreductase, l(+)-lactate-cytochrome c oxidoreductase or catalase. Cytochromes a+a(3) and c were not detected. 3. Zonal centrifugation of whole homogenates indicated complex density distributions of the sedimentable portions of NADH- and NADPH-cytochrome c oxidoreductases, adenosine triphosphatases (ATPases), adenosine pyrophosphatase (ADPase), pyrophosphatase and acid p-nitrophenyl phosphatase. Several different ATPases were distinguished on the basis of their sensitivities to oligomycin and ouabain. 4. Differential centrifugation of whole homogenates at 10(5)g-min left 80-90% of the protein, dithionite-reducible cytochrome b, acid hydrolases and pyrophosphatase in a supernatant (S(1)) together with 65 and 56% of the NADH- and NADPH-cytochrome c oxidoreductases respectively, 25% of the ATPases and 71% of the adenosine monophosphatase. 5. Further analysis of supernatant S(1) revealed the presence of a class of small particles containing NADPH-cytochrome c oxidoreductases and ATPases. 6. At least four different populations of large particles were distinguished. 7. Electron microscopy indicated that one of these corresponded to ;promitochondria' as described by other workers.

Adenosine Triphosphatases↗
PubMed1975

Electrophoretic and centrifugation behaviour of mitochondrial ribonucleic acid from Walker 256 carcinosarcoma.

To investigate the possibility that mitochondrial transcription could be altered in tumours we started by characterizing the RNA obtained from mitochondria, isolated from Walker carcinosarcoma and purified by a procedure devised to compensate for the lower size and density of these organelles in 10-day tumours. The RNA was extracted by the 'hot phenol' technique and analysed by electrophoresis in 2.7 and 2.5% polyacrylamide gels at different running times, identifying the usual cytoplasmic contaminants 28 and 18S peaks plus the other five major peaks at 40, 20.5, 16.3, 15.4, and 4Se. The 28 and 18Se peaks were not eliminated by digitonin treatment of the mitochondria, indicating that they arise from cytoplasmic ribosomes tightly associated with the mitochondria. From its sensitivity to DNAase (deoxyribonuclease), resistance to RNAase (ribonuclease) and coincidence with external marker DNA, the 40Se peak was identified as containing mainly DNA. Sucrosegradient centrifugation for different periods showed a major component at 16.2S, the 28 and 18S cytoplasmic RNA species, peaks at 13.8, 6.4 and 4S and a small 19.5S peak. By polyacrylamide-gel electrophoresis of the purified RNA classes separated by one or two cycles of centrifugation, the following correlation were established: 20.5Se19.5S; 16.3Se16.2S; 15.4Se13.8S. The 6.4S RNA ran as a mixture of 4 and 4.7Se species. When the 20.5Se and 15.4Se RNA species were centrifuged, they behaved as 16.2S and 13.8S respectively, thus suggesting that the 16.2S (16.3Se) arises by cleavage from the 19.5S(20.5Se), the 13.8S (15.4Se) being the other RNA from mitochondrial ribosomes.

Animals↗
PubMed2003

Application of sucrose-gradient centrifugation for selective isolation of Nocardia spp. from soil.

AIMS: To devise and evaluate a method for selective isolation of the less abundant actinomycetes, Nocardia spp. in soil. METHODS AND RESULTS: This newly developed method is based on differentiating Nocardia from other actinomycete taxa by centrifugation. A water suspension of air-dried soil is centrifuged through a gradient consisting of 10, 20, 30, 40 and 50% sucrose at 240 x g for 30 min. The 20% sucrose layer, which is enriched with Nocardia spp., is then diluted and plated on humic acid-vitamin agar supplemented with antibacterial agents. The proposed method consistently achieved selective isolation of Nocardia spp. in all 14 soil samples tested, which accounted for 5-89% of the total microbial population recovered. Tentative taxonomic characterization based on a restriction fragment length polymorphism (RFLP) analysis of the 16S ribosomal DNA suggested that many of the soil isolates could belong to N. asteroides, N. salmonicida or N. uniformis. CONCLUSIONS: Differential centrifugation can successfully and efficiently isolate soil Nocardia populations that are suppressed by conventional dilution plating approaches. SIGNIFICANCE AND IMPACT OF THE STUDY: The development and application of new methodologies with which to isolate less-explored actinomycete taxa is important for improving our knowledge about their taxonomy, ecology and industrial applications.

Anti-Bacterial Agents↗
PubMed2001

Centrifuge polarizing microscope. II. Sample biological applications.

The rationale, design and general performance of the CPM (centrifuge polarizing microscope) were described in Part I of this study (Inoué et al. J. Microsc. 201 (2001) 341-356. In this second part, we describe observations on several biological samples that we have explored over the past two years using the CPM. As described in the first part of the study, although the CPM was basically designed as a high-extinction centrifuge polarizing microscope, it also allows observations of the specimen exposed to high centrifugal fields up to 10 500 x g (earth's gravitational acceleration) in fluorescence (532-nm excitation) and in DIC (differential interference or Nomarski contrast).

Anemia, Sickle Cell↗
PubMed2002

Separation of human lymphocytes from citrated blood by density gradient (NycoPrep) centrifugation: monocyte depletion depending upon activation of membrane potassium channels.

Routine one-step centrifugation procedures (Lymphoprep = LP, Percoll) commonly used for separation of blood cells split the cells into two major fractions. After centrifugation the mononuclear cells (MNC = monocytes and lymphocytes) are located on the top of the separation fluid, whereas erythrocytes and granulocytes have sedimented to the bottom. We now show that a relatively pure lymphocyte suspension can be obtained by one-step centrifugation of citrated blood by using NycoPrep (NP = iohexol), a nonionic X-ray contrast agent. With this gradient medium also the monocytes pass to the bottom, leaving lymphocytes on the top. In parallel separations with LP, which contains Ficoll and a fully dissociated sodium salt of a contrast medium, the results were as usual, i.e. approximately 70-85% lymphocytes and 30-15% monocytes in the top fraction. The monocyte depletion with NP depended upon the use of citrated (ACD) blood and a proper balance of density and osmolality of the gradient medium, and was enhanced by 20 min preincubation with CaCl2 at room temperature. Monocyte depletion could not be obtained with LP. Under optimal conditions (density 1.075 g/ml, osmolality 280-300 mOsm/kg), the monocyte admixture amounted to approximately 1 (0-2)%, in separations with buffy coat samples. For freshly drawn blood, it was necessary to slightly modify the NP solution. The monocyte depletion was counteracted by blockers of K+ channels or by KCl in the cell suspension. Following incubation in NP of Percoll-separated cells, an enhanced release of K+ was observed. The results are interpreted as follows: NP mediates the opening of K+ channels of MNC, which leads to efflux of K+, accompanied with associated anions (Cl-). This reduces the osmolality inside the cells which therefore expel water to maintain osmotic equilibrium. In this regard it appears that monocytes are more sensitive than lymphocytes, their density therefore increasing more, so that they are able to pass the density barrier otherwise exerted by the gradient medium.

Blood Platelets↗
PubMed2004

Enhanced sensitivity of DNA- and rRNA-based stable isotope probing by fractionation and quantitative analysis of isopycnic centrifugation gradients.

Stable isotope probing (SIP) of nucleic acids allows the detection and identification of active members of natural microbial populations that are involved in the assimilation of an isotopically labelled compound into nucleic acids. SIP is based on the separation of isotopically labelled DNA or rRNA by isopycnic density gradient centrifugation. We have developed a highly sensitive protocol for the detection of 'light' and 'heavy' nucleic acids in fractions of centrifugation gradients. It involves the fluorometric quantification of total DNA or rRNA, and the quantification of either 16S rRNA genes or 16S rRNA in gradient fractions by real-time PCR with domain-specific primers. Using this approach, we found that fully 13C-labelled DNA or rRNA of Methylobacterium extorquens was quantitatively resolved from unlabelled DNA or rRNA of Methanosarcina barkeri by cesium chloride or cesium trifluoroacetate density gradient centrifugation respectively. However, a constant low background of unspecific nucleic acids was detected in all DNA or rRNA gradient fractions, which is important for the interpretation of environmental SIP results. Consequently, quantitative analysis of gradient fractions provides a higher precision and finer resolution for retrieval of isotopically enriched nucleic acids than possible using ethidium bromide or gradient fractionation combined with fingerprinting analyses. This is a prerequisite for the fine-scale tracing of microbial populations metabolizing 13C-labelled compounds in natural ecosystems.

Bacteria↗
PubMed1998

Effect of pressure-flow relationship of centrifugal pump on in vivo hemodynamics: a consideration for design.

We have been developing centrifugal pumps for an implantable left ventricular assist device. We manufactured 2 prototype centrifugal pumps (PI, PII). These two have similar designs except for the PII having a volute casing and a large output port. To determine the differences in the hydraulic characteristics between the PI and PII, we carried out in vitro and in vivo experiments. In vitro study showed that the PII had a shallower H-Q curve than that of the PI, and the PII required a pump speed faster than the PI for the same flow rate and pressure head. On the other hand, in vivo study showed that the PII demonstrated a flow pulsatility greater than that of the PI at 1,900 rpm and 8 L/min although no significant change was observed at low pump speeds (< or = 1,500 rpm). This greater pulsatility consisted of a large discharge according to the small differential pressure during the systolic phase and a small discharge according to the large differential pressure during the diastolic phase. In contrast, the PI, having the steeper H-Q curve, showed a small discharge in the systolic phase and a large discharge in the diastolic phase. These results showed that pulsatility synchronized with the native heart beating depended on the slope of the H-Q curve. As a result, the slope of the H-Q curve is important to determine the component of pulsatility synchronized with native cardiac output. Regarding the slope of the H-Q curve, a pump having a volute casing and a large outlet port demonstrates a shallow slope in the H-Q curve. In conclusion, we suggest that a centrifugal pump for use in left ventricular aortic bypass should be designed considering the effect on the native heart pulsatility.

Animals↗
PubMed1998

Evaluation of platelet adhesion and activation on materials for an implantable centrifugal blood pump.

A totally implantable centrifugal artificial heart has been developed in which a pivot bearing supported centrifugal pump is used as a blood pump. The following have been adopted as blood contacting materials in our pump: titanium alloy (Ti-6A1-4V) for the housing and impeller, alumina ceramic (Al2O3) for the male pivots, and ultrahigh molecular weight polyethylene (PE) for the female pivots. Greater antithrombogenicity is required for an implantable blood pump. To examine the thrombogenicity of these materials, we evaluated in vitro platelet adhesion and activation, which may play key roles in thrombogenesis on foreign surfaces. Ti-6A1-4V, Al2O3, and PE were compared with polycarbonate (PC), silicone carbide (SiC), and pure titanium (pTi). Platelet adhesion was assessed using monoclonal antibody (CD61) directed against glycoprotein IIIa. Platelet activation was evaluated by measuring P-selectin (GMP-140) released from irreversibly activated platelets. Each material with a surface area of 16.6 cm2 was incubated with 2.5 ml of plasma or 2.5 ml of heparinized fresh whole blood for 3 h at 37 degrees C. The optical density (OD) at a wavelength of 450 nm for CD61 was 0.93+/-0.35 in PC, 0.34+/-0.13 in PE, 0.27+/-0.13 in pTi, 0.26+/-0.01 in Al2O3, 0.21+/-0.04 in SiC, and 0.12+/-0.12 in Ti-6A1-4V. The GMP-140 levels of the tested materials were not significantly different from the control value (45.9+/-7.2 ng/ml). These results indicate that Al2O3, PE, and Ti-6A1-4V, which are incorporated into our implantable centrifugal pump, have satisfactory antithrombogenic properties in terms of platelet adhesion. However, platelet activation by any material was not observed under the static condition in this study.

Alloys↗
PubMed2000

Jostra Rota Flow RF-30 pump system: a new centrifugal blood pump for cardiopulmonary bypass.

The Rota Flow pump is a fully integrated centrifugal pump system in the Jostra heart-lung machine HL-20 with features such as a less friction mono-pivot bearing system, sealless pump housing, and spiral housing. To evaluate its biocompatibility, antithrombogenesity, and hemolysis, we used it as a main pump of cardiopulmonary bypass (CPB) in coronary artery bypass grafting (CABG) cases and compared it with the BioMedicus pump. From February 1999 to May 1999, 30 consecutive patients underwent CABG under conventional CPB. Fifteen cases were supported by the Rota Flow RF-32 (Group R), and the remaining 15 were pumped by the BioMedicus BP-80 (Group B). In both groups, the flow rate was controlled in an equivalent value. Blood sampling was as follows: preoperative, 60 min after, postoperative Days (POD) 0, 1, and 2. We evaluated the plasma free hemoglobin (fHb) as the hemolysis parameter, beta-thromboglobulin (beta-TG) and platelet factor IV (PF-4) as the platelet deterioration index, C3, C4, and CH50 as complement activation, coagulation function, fibrinolytic factor and thrombomodulin, nitric oxide (NO), and endothelin as endothelial deterioration. This system was very easily and simply controlled and had excellent response. Perioperative laboratory data were not markedly changed in either group. The Rota Flow demonstrated equivalent value of biocompatibility and hemolysis as compared with the BioMedicus BP-80, which is a standard centrifugal pump. After pumping, no thrombus formation or pivot wear was observed inside the pump. This atraumatic, small centrifugal pump is suitable not only for CPB but also for long-term circulatory support.

Analysis of Variance↗
PubMed2000

Development of the NEDO implantable ventricular assist device with Gyro centrifugal pump.

The Gyro centrifugal pump, PI (permanently implantable) series, is being developed as a totally implantable artificial heart. Our final goal is to establish a "functional TAH," a totally implantable biventricular assist system (BiVAS) with centrifugal pumps. A plastic prototype pump, Gyro PI 601, was evaluated through in vitro and in vivo studies as a single ventricular assist device (VAD). Based upon these results, the pump head material was converted to a titanium alloy, and the actuator was modified. These titanium Gyro pumps, PI 700 series, also were subjected to in vitro and in vivo studies. The Gyro PI 601 and PI 700 series have the same inner dimensions and characteristics, such as the eccentric inlet port, double pivot bearing system, secondary vane, and magnet coupling system; however, the material of the PI 700 is different from the PI 601. The Gyro PI series is driven by the Vienna DC brushless motor actuator. The inlet cannula of the right ventricular assist system (RVAS) specially made for this system consists of 2 parts: a hat-shaped silicone tip biolized with gelatin and an angled wire reinforced tube made of polyvinylchloride. The pump-actuator package was implanted into 8 calves in the preperitoneal space, bypassing from the left ventricle apex to the descending aorta for the left ventricular assist system (LVAS) and bypassing the right ventricle to the main pulmonary artery for the RVAS. According to the PI 601 feasibility protocol, 2 LVAS cases were terminated after 2 weeks, and 1 LVAS case and 1 RVAS were terminated after 1 month. The PI 700 series was implanted into 4 cases: 3 LVAS cases survived for a long term, 2 of them over 200 days (72-283 days), and 1 RVAS case survived for 1 month and was terminated according to the protocol for a short-term antithrombogenic screening and system feasibility study. Regarding power consumption, the plastic pump cases demonstrated from 6.2 to 12.1 W as LVAS and 7.3 W as RVAS, the titanium pump cases showed from 10.4 to 14.2 W as LVAS and 15.8 W as RVAS. All cases exhibited low hemolysis. The renal function and the liver function were maintained normally in all cases throughout these experimental periods. In the 2 RVAS cases, pulmonary function was normally maintained. No calves demonstrated thromboembolic signs or symptoms throughout the experiments except Case 1 with the plastic pump. However, in the plastic pump cases, bilateral renal infarction was suspected in 2 cases during necropsy whereas no abnormal findings were revealed in the titanium pump cases. There were also no blood clots inside the PI 700 series. As for the 601, the explanted pumps demonstrated slight thrombus formations at the top and bottom pivots except in 1 case. The Gyro PI series, especially the PI 700 series, demonstrated superior performance, biocompatibility, antithrombogenicity and low hemolysis. Also, the durability of the actuator was demonstrated. Based on these results, this titanium centrifugal pump is suitable as an implantable LVAS and RVAS. It is likely that the Gyro PI series is a feasible component of the BiVAS functional TAH.

Animals↗