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PubMed2002

Flow rate and pressure head estimation in a centrifugal blood pump.

Considering a miniaturization of percutaneous cardiopulmonary support (PCPS) system, we have developed a pump system that can estimate flow rate and pressure head in the circuit. A commercially available centrifugal blood pump (C1E3, Kyocera Co., Ltd., Kyoto, Japan) with an exclusive motor driver was used in the experiment. In this system, the motor revolutions per minute and torque were used to derive an estimation equation. Taking into consideration fluid viscosity, the accuracy of the estimation was increased. Bovine blood was used to evaluate the system in vitro. The average maximum difference between the estimated flow rate and the measured flow rate was 0.56 L/min (for 98% accuracy). The average difference between the estimated pressure head and the measured pressure head was 30.7 mm Hg (for 94.2% accuracy). Because of the stability of the estimations, we believe this system has the possibility of use for real-time monitoring and miniaturization of PCPS system.

Animals↗
PubMed2003

Leakage flow measurements in a bio-centrifugal ventricular assist device model.

The magnetically suspended impeller centrifugal blood pump (MSCBP) has shown its superiority as compared to other artificial hearts. However, it is still plagued by hemolysis and thrombus formation in the clearance gap between the impeller shroud surface and the pump casing. In an early study, a 5 : 1 scaled up model was built in order to measure the radial and tangential velocities at the gap under the operating condition of a flow coefficient (Phi) of 0.04 using a hot wire anemometer. In this study, velocity profiles were obtained at two critical flow coefficients, Phi = 0.078 (fully opened condition) and 0 (fully closed condition), to further the understanding of the flow field in the pump. Similar to the operating condition, the vector plot of the resultant velocity under these two flow coefficients showed that there were no vortices in the gap and a washout mechanism presented at the region around the starting of the splitter plate of the double volute. It was found that the washout mechanism was more obvious in the fully closed condition than in the fully opened condition. This has suggested that with real life operation, the pump could occasionally be operated at a relatively lower flow rate (e.g., under the resting condition of the patient) to obtain a good washout in the gap and thus reduce thrombus formation at the pump casing.

Blood Flow Velocity↗
PubMed2001

Current topics on centrifugal plasmapheresis technologies.

In the field of plasmapheresis centrifugal technology has recently focused on the collection of peripheral blood stem cells (PBSCs) for both autologous and allogeneic transplantation in patients with malignancies or hematological diseases and on donor plasmapheresis. PBSC transplantation is rapidly replacing bone marrow transplantation in such patients. Various kinds of apheresis equipment were applied and described for PBSC collection. Comparison among machines is described. Allogeneic PBSCs were collected from healthy normal donors. Specific attention to the dose and administration duration of granulocyte colony-stimulating factor and a careful apheresis procedure should be made for donor safety. In platelet transfusion practice, a platelet concentrate product derived plateletpheresis from a single donor is preferable to minimize and to prevent adverse transfusion reactions. The status of platelet collection and its efficacy by various kinds of plateletpheresis equipment are discussed. The Amicus and CCS might be preferable plateletpheresis machines because of their collection efficiencies and wider indication for donors. With the limited number of donors, it is essential that plateletpheresis should be more effectively performed and managed by each regional blood center. The status of plasma and red cell collection by apheresis technologies is described also briefly.

Centrifugation↗
PubMedDate not supplied

Hydroxyethyl starch as an experimental adjunct to leukocyte separation by centrifugal means: review of safety and efficacy.

A total of 1,921 leukapheresis procedures have been performed on 532 normal and CML donors at six research institutions, for the purpose of supporting granulocytopenic leukemia patients during infectious episodes. The addition of HES alone or in combination with either etiocholanolone or dexamethasone, resulted in a significant increase in the numbers of leukocytes (granulocytes) harvested by continuous and noncontinuous flow centrifugation. Normal donors participating in these programs were monitored prior to and immediately following each procedure by standard laboratory methods which revealed no serious or abnormal changes occurring as a result of the procedure in those undergoing single or multiple donations with these agents. CML donors tolerated the addition of only HES well, as evidenced by the lack of toxic reactions in three donors undergoing 101 to 121 procedures.

Blood Donors↗
PubMedDate not supplied

Improved granulocyte collection from normal donors by combination of continuous-flow centrifugation and filtration leukapheresis.

A total of 30 leukaphereses were performed with the Aminco Cellseparator on 27 healthy donots. Pretreatment by steroids and addition of fluid gelatin to the input line was performed in all runs. The combination of continuous flow centrifugation and filtration leukapheresis (CFC-FL) in nine of the 30 runs resulted in a highly significant increase of the yield to a mean of 59.6 X 1o(9) granulocytes as compared with a mean of 30.8 X 10(9) granulocytes obtained with conventional CFC. This significance is valid for the total yield of granulocytes, the yield per hour of run, or per liter of blood processed. No adverse reaction occurred.

Blood Cell Count↗
PubMedDate not supplied

The acquisition of granylocytes by leukapheresis: a comparison of continuous flow centrifugation and filtration leukapheresis in normal and corticosteroid-stimulated donors.

Leukapheresis by continuous flow centrifugation (CFC) or filtration (FL) were compared in untreated and corticosteroid-treated donors. The administration of prednisone 60 mg orally 10 to 12 hours before leukapheresis increased significantly both the donor's prepheresis WBC counts and the total granulocyte yields by CFC or FL. Dexamethasone 6 mg iv at the start of FL did not increase granulocyte yields significantly. In untreated donors FL yielded 0.25 x 10(10) granulocytes per liter donor blood processed as compared with 0.05 x 10(10) per liter in CFC donors. Corticosteroid premedication has a greater relative effect in increasing yields by CFC than by FL. Donor reaction rates were between 4 and 6 per cent for both procedures.

Blood Donors↗
PubMedDate not supplied

Discontinuous flow centrifugation leukapheresis and neutrophil function.

Neutrophils collected by discontinuous flow centrifugation using hydroxyethyl starch were evaluated. Morphology was studied by light and electron microscopy. Functional integrity was assessed by measuring viability, chemotaxis, phagocytosis, and killing power. The harvested granulocytes were morphologically normal and showed no functional impairment.

Cell Survival↗
PubMedDate not supplied

Storage of platelets prepared by discontinuous flow centrifugation.

Platelet concentrates were prepared by plateletpheresis using discontinuous flow centrifugation. Platelet units were stored in PL-146 bags of 300 ml and 2,000 ml capacity, and in vitro measures helpful in predicting platelet viability were compared. Storage in bags of 300 ml capacity led to significant fall in pH, decreased recovery from osmotic stress, and deterioration of morphology in 24 hours. Storage lesions were significantly decreased by use of 2,000 ml capacity bags.

Blood Cell Count↗
PubMedDate not supplied

Properties of neutrophils collected by discontinuous-flow centrifugation leukapheresis employing hydroxyethyl starch.

The properties of neutrophils, collected by discontinuous-flow centrifugation leukapheresis in the presence of hydroxyethyl starch and citrate were studied in an attempt to insure that cells harvested in this fashion are suitable for transfusion. Neutrophils obtained from leukocyte units prepared for transfusion by leukapheresis were found to perform similarly to those isolated from the venous blood of corresponding donors prior to the pheresis procedures when assessed by morphology, viability, hexose monophosphate shunt activity, superoxide anion generation, nitroblue tetrazolium dye reduction, chemiluminescence, adherence to nylon fibers, random mobility, chemotaxis and staphylococcal killing. The results compared favorably with values previously established for healthy control subjects. Neutrophils prepared in this manner should serve as a satisfactory blood component.

Centrifugation↗
PubMedDate not supplied

The sterility of platelet and granulocyte concentrates collected by discontinuous flow centrifugation.

Platelet concentrates prepared by a discontinuous flow centrifugal technique (Haemonetics) were examined for evidence of bacterial contamination and subsequent growth from 3 to 11 days after collection. Of the 126 platelet concentrates examined, 4 revealed bacterial growth. However, the growth patterns indicated contamination during the microbiologic manipulations rather than contamination of the units during preparation. These studies indicate that platelet concentrates prepared using the Haemonetics Blood Processor can be safely transfused for up to three days after collection if stored at 4 to 6 C.

Bacteria↗
PubMedDate not supplied

Gram-negative sepsis treated with neutrophils collected exclusively by intermittent flow centrifugation leukapheresis.

The effectiveness of neutrophils prepared for transfusion by intermittent flow centrifugation leukapheresis (IFCL) as treatment for serious bacterial infections in neutropenic patients has not been documented in the literature. Their value, in fact, has been questioned. We report that IFCL neutrophils are similar to cells prepared by other techniques in the ability to support neutropenic patients with culture-proven, gram-negative sepsis unresponsive to antibiotics.

Adolescent↗
PubMedDate not supplied

Effects of centrifugation leukapheresis with hydroxyethyl starch on the complement system of granulocyte donors.

In granulocyte donors during centrifugation leukapheresis (CL), total hemolytic complement, Clq, C3, factor B, and properdin decreased, but only to the extent expected from hemodilution. Crossed immunoelectrophoresis showed no C3 conversion in plasma obtained from the leukapheresis appeared during CL or in donor plasma immediately after CL. When serum was incubated with hydroxyethyl starch, total hemolytic complement did not decrease and C3 conversion was not detected by crossed immunoelectrophoresis. This investigation revealed no evidence that complement activation is associated with CL.

Blood Donors↗
PubMedDate not supplied

Function of irradiated polymorphonuclear leukocytes obtained by buffy-coat centrifugation.

Several studies suggest that transfusion of polymorphonuclear leukocytes (PMNs) may be beneficial in the treatment of septic neonatal patients. Because of expense, donor availability, and the technical effort involved in obtaining PMNs by intermittent or continuous flow leukapheresis, buffy coat centrifugation of whole blood has been suggested as an alternative source. An in vitro study was performed to determine whether PMNs collected by this method have adequate oxidative and migratory function measured by chemiluminescence (CL) and chemotaxis under agarose (CT), respectively. Whole blood samples from six adult volunteers were drawn into citrate-phosphate-dextrose-adenine-one and stored at 4 degrees C for 0 to 48 hours. One-half of each sample was irradiated with 1500 rads. PMNs isolated from the buffy coat of these samples had greater than 80 percent normal CT and CL following 0 to 28 hours of storage in whole blood. Irradiation caused no depression in function. Units of whole blood yielded 1.11 +/- 0.40 X 10(9) PMNs per unit. This study indicates that transfusion of radiated PMNs obtained from stored whole blood that is less than 28 hours old is reasonable to use in studies involving PMN transfusions.

Adult↗
PubMedDate not supplied

Two-stage separation of immature and mature T lymphocytes from myeloerythroid clonogenic bone marrow cells by apheresis and elutriation centrifugation.

Because graft-versus-host disease remains a major complication in allogeneic bone marrow transplantation, a number of techniques capable of removing mature T lymphocytes from bone marrow cells have been attempted. The authors describe a simple two-step procedure using counterflow centrifugation elutriation (CCE) that eliminated 95 to 98 percent of the mature T lymphocytes and greater than 97 percent of the T lymphocyte colony-forming units (CFU-T) while concentrating the bone marrow myeloid colony-forming cells. Viability was greater than 98 percent, and 72 to 98 percent of the total cells separated were recovered. Lymphocyte depletion was substantiated by both morphologic and phenotypic criteria using monoclonal antibodies to T lymphocytes, as well as by responsiveness in mixed-lymphocyte cultures and to mitogens. In addition, this technique separated the lymphoid colony-forming cells from the larger myeloid colony-forming cells. It was concluded that this simple two-step CCE procedure can be used to separate T lymphocytes and CFU-T from myeloid colony-forming cells and offers a means of purging T lymphocytes from large numbers of marrow cells that may be required for human allogeneic bone marrow transplantation.

Aging↗
PubMedDate not supplied

Comparison of autosurge versus surge protocols for discontinuous-flow centrifugation plateletapheresis.

Autosurge is a new, highly automated protocol for collecting platelets by centrifugation plateletapheresis. It was developed to allow optimal cell collections with less operator effort than was required with the earlier, standard Surge protocol. The authors compared the cellular content of 201 platelet concentrates prepared by Surge with that of 120 concentrates prepared by Autosurge by the same group of operators, using the same cell separator. Platelet yields were similar (p = 0.775) for both protocols (mean X 10(-11) were 3.54 and 3.57 for Surge and Autosurge, respectively) and when subdivided according to preapheresis donor blood platelet counts, hematocrits, and leukocyte counts. Although platelet yields were comparable in concentrates prepared by either protocol, high donor hematocrit had less adverse effect on platelet yield when the Autosurge protocol was used. The composition of concentrates differed between protocols in that leukocytes contamination was significantly less (p less than 0.001) in units collected by Autosurge (3.4 X 10(8)) than in those collected by Surge (5.8 X 10(8)). Operator involvement can be less intense with Autosurge because the protocol includes automatic adjustment of cell separator settings for optimal plateletapheresis. The results of the direct comparison study were confirmed by data from 509 additional plateletapheresis procedures performed during routine blood center operation. Autosurge should replace Surge because the former easily produces platelet concentrates that contain fewer leukocytes without compromising platelet yields.

Blood Component Removal↗
PubMed1993

CD34+ progenitors and colony-forming units-granulocyte macrophage are recruited during large-volume leukapheresis and concentrated by counterflow centrifugal elutriation.

The recruitment of mononuclear cells (MNCs), colony-forming units-granulocyte macrophage (CFU-GM), lymphocyte subpopulations, and CD34+ progenitor cells was studied during large-volume (15-25 L blood processed) peripheral blood stem cell (PBSC) harvests. Normal donors (n = 13) underwent a 4-hour leukapheresis designed to maximize PBSC yield (blood flow rate, 85 mL/min). Mean (+/- SD) volume processed was 17.7 +/- 0.4 L, and yield was 2.4 +/- 0.7 x 10(10) white cells containing 99 percent MNCs and 1.3 mL red cells per L of blood processed. Postapheresis hematocrit, platelets, and MNCs were reduced from preapheresis values by 7, 35, and 23 percent, respectively (p < 0.05). In nine donors, the component was collected as four 1-hour samples, and culturing of CFU-GM and flow cytometric analysis of lymphocyte subpopulations and CD34+/HLA-DR+ cells were done in individual samples. Total CFU-GM were 2.4 +/- 1.4 x 10(6) (3.0 +/- 1.8 x 10(4) CFU-GM/kg) and lymphocytes were 20.8 x 10(9), with 75 percent CD3+ T cells, 10 percent CD19/CD20+ B cells, and 17 percent natural killer cells. A more than twofold increase in CFU-GM and CD34+ cells was noted over the course of the 4-hour procedure (p < 0.05). In four donors, the leukapheresis component underwent counterflow centrifugal elutriation (CCE), which separated it into four fractions in an attempt to concentrate CD34+ and CFU-GM progenitors and to deplete T-lymphocytes on a large scale. There was a 1.8-, 4.6-, 3.9-, and 0.32-fold increase in CFU-GM in the four fractions relative to the unseparated component.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2000

Separation of dendritic cells from highly purified human monocytes by counterflow centrifugation induces tissue factor expression.

BACKGROUND: In vitro generation of dendritic cells (DCs) from human monocytes represents a promising tool in immunotherapy. However, it is not known whether the separation of DCs from monocytes induces tissue factor expression and therefore may trigger coagulation in patients receiving these DC preparations. The aim of this study is thus to analyze tissue factor expression on monocyte-derived DCs and to compare their ability to trigger thrombin generation to that of macrophages obtained from the same monocytes. STUDY DESIGN AND METHODS: Human monocytes are separated by leukapheresis and washed by using counterflow centrifugation in sterile, endotoxin-free conditions. Macrophages are grown from human monocytes in the presence of GM-CSF alone and immature DCs are grown in the presence of GM-CSF plus IL-4 for 5 days with fetal calf serum (IDC-FCS). Immature DCs are also grown from human monocytes for 7 days in the presence of GM-CSF plus IL-4 with human group AB serum (IDC-HS). The addition of prostaglandin E(2) and TNFalpha in this culture medium at Day 5 leads to mature DCs (MDC-HS). Tissue factor mRNA expression is studied by RT-PCR analysis. Tissue factor antigen is measured by ELISA in cell lysates and by direct flow cytometry. The procoagulant activity of intact cells is assessed by using an amidolytic assay or a chronometric assay. RESULTS: IDC-FCS express tissue factor mRNA and antigen and trigger thrombin generation. Procoagulant activity of IDC-FCS is dependent on both tissue factor expression and exposure to anionic phospholipid. Monocyte-derived macrophages cultured for 5 days with GM-CSF alone express lower levels of tissue factor mRNA, tissue factor antigen, and procoagulant activity than IDC-FCS. IDC-HS and MDC-HS also express high levels of tissue factor mRNA and antigen and support procoagulant activity. CONCLUSION: Monocyte-derived DCs express a high level of functional tissue factor and support procoagulant activity. This finding should be taken into account in clinical trials.

Animals↗
PubMed2002

A newly developed gel centrifugation test for quantification of RBC-bound IgG antibodies and their subclasses IgG1 and IgG3: comparison with flow cytometry.

BACKGROUND: Novel gel centrifugation test (GCT) cards were evaluated with respect to their ability to estimate the quantity of IgG on RBCs and the determination of the IgG subclasses IgG1 and IgG3. STUDY DESIGN AND METHODS: In 65 patients with a positive DAT, the amount of IgG-gamma-, IgG1, and IgG3 on RBCs was examined by use of GCT cards and flow cytometry (FC) in parallel. The results were correlated with the presence or absence of hemolysis. In addition, D+ RBCs were studied after sensitization with anti-D sera from 22 alloimmunized pregnant women. RESULTS: The amount of IgG on the RBCs as determined by GCT dilution cards correlated with FC (r=0.70, p < 0.0001). IgG subclass results as determined by GCT IgG subclass cards were confirmed by FC in 14 cases with an anti-IgG-gamma-chain titer > or =300, whereas IgG subclass cards were not suitable in cases with anti-IgG-gamma-chain titers less than 300. In 44 patients with 2+ or 3+ DAT in the GCT and anti-IgG-gamma-chain titer < or =30, no hemolysis was observed, whereas hemolysis occurred in 13 of 14 patients with an anti-IgG-gamma-chain titer > or =300. GCT data obtained by IATs with anti-D sera were concordant with FC results. CONCLUSION: There is a correlation between the amount of RBC-bound IgG and immune hemolysis. The GCT cards that detect the anti-IgG-gamma-chain may be useful to predict hemolysis in patients with a 2+ or 3+ DAT in the GCT. The diagnostic value of GCT cards for IgG subclass testing should be investigated further.

Adult↗