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PubMedDate not supplied

[Effect of anticoagulants on lymphocyte isolation by density gradient centrifugation].

The authors compared the efficiency of isolation and the purity of lymphocytes obtained by the method of centrifugation in a gradient of ficoll and uropoline from blood obtained on ACD fluid and on heparin. Isolation of lymphocytes from the blood obtained on heparin was more efficient (60%) and useful. For removal of platelets it was necessary to use additional centrifugation in a saccharose gradient or application of aggregating agents during isolation of lymphocytes obtained on heparin or ACD fluid.

Anticoagulants↗
PubMed1980

Effects of centrifugation, storage, and contamination of amniotic fluid on its total phospholipid content.

The total phospholipid content of the supernatant fluid decreases rapidly with increasing relative centrifugal force when amniotic fluid is centrifuged. Possible explanations for this are discussed. The effect of storage on the total phospholipid content of amniotic fluid at different temperatures and the influence of contamination with blood and meconium are also described.

Amniotic Fluid↗
PubMed1980

Cardiovascular responses of man exposed to +Gz accelerations in a centrifuge.

Cardiovascular investigations were conducted in male volunteer subjects exposed to +Gz accelerations. Some of them did not have any previous experience of the centrifuge. Electrocardiogram, blood pressure, heart rate, stroke volume, and cardiac output were recorded. Accelerations ranging from +1.5 Gz to +6 Gz were applied during periods of from 30 s to 20 min. Acceleration was achieved in 10-90 s. Heart rate markedly increased as a function of acceleration intensity, reaching 160 beats/s. Decreases in cardiac output (30-40%) and stroke volume were also observed. Protection by an anti-G suit reduces tachycardia. Accelerations induce various electrocardiographic disorders lasting several minutes after the stress has been stopped. These are sometimes the first symptoms of functional cardiovascular failure. The centrifuge turns out to be an excellent screening tool. However, when used for testing various aircrew equipment, strict monitoring of the subjects is required.

Adult↗
PubMedDate not supplied

[Effect of periodic "head-foot" G-forces in a short-radius centrifuge on human cardiovascular system responses].

During 3- and 6-day immersion studies test subjects were two or three times a day (60 min each time) exposed to head-to-feet acceleration of 1-2 G in a 2 m arm centrifuge. In 297 runs cardiovascular reactions were compared with respect to their adaptation or cumulation. The results showed that the principle of periodic application of acceleration in a short-arm centrifuge as a countermeasure against cardiovascular deconditioning can be complemented by the principle of cyclic exposures. The study demonstrated that 3-day cycles including 60 min exposures to 1-2 Gz twice a day were most efficient.

Blood Pressure↗
PubMed1980

Some problems in using density gradient centrifugation for synchronization of L5178Y-S cells.

The application of sucrose gradient sedimentation for synchronization of murine lymphoma L5178Y-S cells was investigated. Centrifugation of the cells in a linear 2--10% sucrose gradient in Fischer's medium allows to obtain populations enriched in (I) young cells, (II) DNA-synthesizing cells, and (III) old cells. Population I showed highest degree of synchrony and contained at least 70% G1 cells. However, only a proportion of cells from population I progressed normally (approximately 30% of cells from this population remained in G1 during post-separation incubation). It was shown that the sucrose concentrations used for separation did not affect growth of L5178Y-S cells. On the other hand, relatively gentle mechanical treatment severely inhibited proliferation of these cells. It is suggested that excellent adaptation of cells to the culture medium and complete stability of the medium's composition are the prerequisites for a successful synchronization of L5178Y cells by gradient centrifugation.

Animals↗
PubMed1980

Effect of weightlessness and centrifugation on red cell survival in rats subjected to space flight.

Rats were flown aboard the Soviet biosatellite Cosmos 936 for 18.5 d during August, 1977. Five rats were subjected to near-weightless space flight, as with Cosmos 782, and five rats were subjected to a 1-G force via an on-board centrifuge. These rats and three control groups were injected with 2-14C glycine 19 d preflight. The flight rats were recovered from orbit after 18.5 d of space flight. Erythrocyte hemolysis and lifespan were evaluated in the five groups of rats by quantitation of radioactive carbon monoxide exhaled in the breath which arises from the breakdown of the previously labeled hemoglobin. The results support our previous findings wherein hemolysis was found to increase as a result of weightless space flight. A comparison to the centrifuged animals indicates that artificial gravity attenuates the effect of weightlessness on hemolysis and appears to normalize the hemolytic rate in the early postflight period.

Animals↗
PubMed1995

Separation of feline bone marrow cells by counterflow centrifugal elutriation. Identification and isolation of presumptive early and late myeloid/erythroid progenitors.

Counterflow centrifugal elutriation (CCE) has been used to separate nucleated cells from mammalian bone marrow on the basis of size with the resultant isolation of hematopoietic cells in varying stages of lineage development. We examined the feasibility of identifying and isolating such cells from feline bone marrow. CCE was performed with a Beckman J6MI centrifuge and a Sanderson chamber, using a fixed rotor speed of 3000 rpm and collection of cells at (1) 16-, (2) 21-, (3) 25-, (4) 32 ml/min, and (5) a rotor off fraction. Recovery of the total input cells in four replicate experiments averaged 86%, with the maximum number of recovered cells in fraction 4. Analysis by flow cytometry and monoclonal antibodies revealed mononuclear cells in fractions 1 and 2 and early and late differentiating myeloid/erythroid cells in fractions 2 through 5. T lymphocytes and alloreactivity in a mixed lymphocyte reaction (MLR) were restricted to fractions 1 and 2; removal of T cells and MLR activity was accomplished by immunomagnetic depletion. In vitro cultures for clonogenic cells revealed CFU-GM and BFU-E colonies in fractions 2 through 5, with fraction 4 containing the greatest absolute number of myeloid colonies and fractions 3 and 4 the majority of the erythroid colonies. More important, in examining the plating efficiency for clonogenic cells in the different fractions it was found that this increased significantly in fractions 2 and 3 when the culture time was extended from 7 to 14 days; in contrast, fractions 4 and 5 reached their maximum plating efficiency within 7 days with no further increase on day 14. We interpret these findings to indicate the presence of late differentiating progenitors in the large-cell size fractions 4 and 5, while the smaller mononuclear cells in fractions 2 and 3 represent an earlier, more primitive population of hematopoietic cells requiring an extended time in culture for full colony development.

Animals↗
PubMed1994

An effective method for depleting mature T lymphocytes from bone marrow cells--two-step Percoll centrifugation.

In the present paper we have observed the effect of discontinuous gradient two-step Percoll centrifugation on depleting mature T lymphocytes from normal bone marrow. The pre-/post-Percoll percentage of CD34+, and Leu4+ cells in MNC was counted by using APAAP technique. As the two-step Percoll centrifugation is simple, and time saving, and decreases the incidence of contamination of cultured cells as well, This technique may be of value in serum-free culture of hematopoietic cells and immunological studies.

Antigens, CD↗
PubMed1979

Centrifugal analyzer method for total bilirubin in serum by use of diazotized 2-chloroaniline-5-sulfonic acid.

We describe two centrifugal analyzer methods for measuring total bilirubin in serum. Diazotized 2-chloroaniline-5-sulfonic acid is used in both. In the first procedure, ethylene glycol and methanol are used as an accelerator solvent; results correlate well with those by a Jendrassik and Grof method adapted to the centrifugal analyzer, but there is considerable hemolysis interference. In the second method, dimethyl sulfoxide is used with the ethylene glycol/methanol solvent and almost all hemolysis interference is eliminated. For either method, a 15-microliter sample is required. In the second method, instrument response is linearly related to concentration to 250 mg/L and the within-run precision (CV) is about 1%.

Azo Compounds↗
PubMed1994

Dynamic characteristics of centrifuges.

In specifications of high performance human centrifuges, different definitions of the term "G-load onset rate" occur. This paper compares four of these definitions and discusses the motivation and its advantages and disadvantages from the technical point of view. The four definitions are applied to a high performance human centrifuge to generate Gz load versus time profiles with constant rates of G onset. In order to illustrate and measure the differences between the different methods, some evaluation parameters like "overall transition time" (time between two different g levels), and "lower transition time" (time to reach the constant onset rate from the lower g-base level) are developed. Further, the influence of a tolerance threshold for the Gx- and Gy-load components in a Gz load profile on the evaluation parameters are discussed. The admission of a relative small tolerance threshold (< or = 0.3 g) leads to a drastic reduction (40%-50%) of the evaluation parameters.

Acceleration↗
PubMed1994

Lipid determination from monophasic solvent mixtures: influence of uneven distribution of lipids after filtration and centrifugation.

Reasons for the variation in erythrocyte lipid extraction were investigated. We found that there was an uneven distribution of lipids after filtration (up to 10% accumulated in the filtrates) or centrifugation (up to 10% in the top fraction) of several apparently monophasic extraction systems. The uneven distribution was more pronounced in the systems containing relatively more water, or, generally speaking, with more nonpolar solvents. Ill-defined procedures using either filtration or centrifugation, therefore, could be the cause for variations in lipid extraction. A way to prevent the uneven distribution has been developed and is discussed.

1-Propanol↗
PubMed1993

Allogeneic bone marrow transplantation for leukemia with marrow grafts treated by counterflow centrifugation.

Eighty consecutive patients were transplanted with human leukocyte antigen (HLA)-identical sibling marrow for acute myelogenous leukemia (AML, N = 29), acute lymphoid leukemia (ALL, N = 23), or chronic myelogenous leukemia (CML, N = 28). Donor marrow was depleted of lymphocytes using counterflow centrifugation. Median age of the recipients was 31 years. Pretransplant conditioning consisted of cyclophosphamide and fractionated total body irradiation (TBI). Graft failure occurred in 4 of 77 evaluable patients (5%). The probability of acute graft-versus-host disease (GVHD) > or = grade 2 at day 100 after transplantation was 15%. The projected 3-year estimate of extensive chronic GVHD was 12%. The projected 3-year probability of relapse was 30% in transplants for AML in first complete remission (CR1), 35% after transplantation for ALL in CR1, and 38% after transplantation for CML in first chronic phase (CP1). The projected 3-year probability of leukemia-free survival (LFS) was 56% after transplantation for AML-CR1, 42% in patients transplanted for ALL-CR1, and 49% after transplantation for CML-CP1. The chance of relapse was significantly reduced in a cohort of 72 standard risk patients conditioned with a regimen intensified by the addition of anthracyclines. This resulted in DFS at 4 years after BMT of 63% compared to 39% in a historical control group. Enrichment of the donor marrow with NK-cells did not increase the incidence of GVHD, but did neither decrease the relapse rate after BMT. In bone marrow transplantation for leukemia, counterflow centrifugation is a useful technique for the prevention of GVHD. Further efforts should be made to reduce relapse-rate, particularly in high risk patients.

Adolescent↗
PubMed1995

A controlled comparison of the efficacy of hetastarch and pentastarch in granulocyte collections by centrifugal leukapheresis.

Compared with hetastarch (HS), the low molecular weight analog pentastarch (PS) has been reported to be equally effective for granulocyte collection by centrifugal leukapheresis, to result in fewer adverse donor reactions (ADR), and to have a more rapid elimination profile. We prospectively compared the granulocyte collection efficiency (GCE), granulocyte yield, and ADR in 72 randomly paired granulocytapheresis procedures from 36 volunteer donors using the model CS-3000 Plus Blood Cell Separator (CS) and either PS or HS as the sedimenting agent. Paired collections from each donor allowed us to compare the two agents directly while controlling for intrinsic donor differences. In 33 of 36 (92%) donors, HS procedures were significantly more efficient than PS procedures (P < .001). As an average, HS collections yielded 2.3 +/- 0.67 x 10(10) granulocytes at 58% +/- 8.8% GCE, whereas PS procedures resulted in 1.4 +/- 0.76 x 10(10) granulocytes at 33% +/- 15% GCE. No starch-induced ADR were seen with either agent. For granulocyte harvests using the CS, (1) in most donors, using HS as the red blood cell sedimenting agent during centrifugal leukapheresis results in significantly higher (nearly twofold) GCE and larger granulocyte yields in comparison with using PS, (2) ADR were not observed with either agent, and (3) the potential benefit of more rapid PS elimination should be balanced against significantly lower granulocyte yields.

Adsorption↗
PubMed1996

Study of secondary flow in centrifugal blood pumps using a flow visualization method with a high-speed video camera.

Four pump models with different vane configurations were evaluated with flow visualization techniques using a high-speed video camera. These models also were evaluated through in vivo hemolysis tests using bovine blood. The impeller having the greatest fluid velocity relative to the impeller, the largest velocity variance, and the most irregular local flow patterns in the flow passage caused the most hemolysis. Even if the pumps were operated at almost the same speed (rpm) at the same output, the impeller showing more irregular flow patterns had a statistically greater rate of hemolysis. This fact confirms that the existence of local irregular flow patterns in a centrifugal blood pump deteriorates its hemolytic performance. Thus, to optimize the design of the pump, it is very important to examine the secondary flow patterns in the centrifugal blood pump in detail using flow visualization with a high-speed video camera.

Animals↗
PubMed1996

A magnetically suspended and hydrostatically stabilized centrifugal blood pump.

A magnetically suspended centrifugal blood pump intended for application as a long-term implantable ventricular assist device has been built and tested. The rotor is freely suspended in the blood by magnetic and hydrostatic restoring forces. This design obviates the need for bearings and shaft seals, and eliminates the problems of reliability and thrombogenicity associated with them. The positional stability and hydrodynamic performance of the pump has been characterized in vitro at flows of up to 10 L/min at physiologic pressures. Radial position control is realized by an analog electronic feedback control system. The pressure distribution in the fluid surrounding the rotor provides dynamic control in the axial direction with no active feedback. Rotor excursion is less than 50 microns (mu) when the housing receives an impulse peaking at an acceleration of 40 g or upon sudden blockage of the flow. In vitro blood measurements indicate an acceptable level of hemolysis compared with that of a standard centrifugal pump.

Animals↗
PubMed1996

Clinical application of a newly developed autoflow control system for the Terumo centrifugal pump: from external control to built-in direct control.

We have developed an autoflow control system for the Terumo Capiox centrifugal pump, the SP-101. First, we made an external control system regulated by a personal computer through a serial communications line. Although an in vivo experiment using a goat showed excellent performance in regulating the flow, a communication error that caused an abrupt and instantaneous flow fluctuation was noted occasionally. Therefore, we incorporated a check-sum function to solve this problem. After this improvement, 5 patients safely underwent cardiopulmonary bypass using a pump having this autoflow control. As the next step for more practical usage, we developed a built-in autoflow control system in which the control device is entirely incorporated into the console without a communications line. This system demonstrated better response and reliability than the external control system and was applied successfully in 3 patients. In conclusion, this autoflow mode will expand the usage of centrifugal pumps through improved handling.

Algorithms↗
PubMed1996

Subchronic use of the St. Jude centrifugal pump as a mechanical assist device in calves.

The purpose of this experiment was to study the effects of the St. Jude Lifestream centrifugal pump on hemodynamic and hematologic parameters and the incidence of postmortem findings in a subchronic ex vivo left ventricular assist animal model. Five calves were implanted with the pump as a left ventricular assist device (left atrial to thoracic aorta bypass) and studied for 96 h of continuous pumping under identical conditions. Heparin (100 IU/kg) was administered only in the initial saline pump prime. Throughout the protocol, mean arterial and central venous pressures averaged 102.1 +/- 4.6 and 3.4 +/- 2.2 mm Hg, respectively. Pump flow was 47.8 +/- 8.4 ml/kg/min at a mean pump speed of 1,676.3 +/- 106.1 rpm. No clinical abnormalities or mechanical malfunctions attributable to the pump were detected during the 96 h of continuous pumping for each calf. Mean plasma-free hemoglobin after 96 h was 3.9 +/- 3.7 mumol/L (p = 0.337 compared to baseline). At post mortem, renal infarctions were detected in 1 calf. No other pump-associated lesions were detected in any of the other calves. We have concluded that the St. Jude Lifestream centrifugal pump functions reliably during 96 h of continuous left heart bypass in a calf model.

Animals↗
PubMed1996

Less blood damage in the impeller centrifugal pump: a comparative study with the roller pump in open heart surgery.

A centrifugal pump with an impeller (Nikkiso Centrifugal Pump, Model HPM15; Nikkiso Co. Ltd.) was applied to cardiopulmonary bypass (CPB) in 14 patients who underwent elective coronary artery bypass grafting. Serum hemoglobin level, platelet count, and serum beta-thromboglobulin (beta TG) level were measured during CPB. The results were compared with those obtained in a comparative roller pump (RP) group (n = 10). There was no difference in the time on CPB between the NP (109 min) and RP (121 min) groups. The serum beta TG level (ng/ml) was lower in the NP group than in the RP group (obtained 90 min after the initiation of CPB). The plasma-free hemoglobin level also was lower in the NP group than in the RP group (obtained 90 min after the initiation of CPB, 120 min after the initiation of CPB, immediately after the termination of CPB, 3 h after termination of CPB; p < 0.01). There was no significant difference in platelet depletion. The HPM15 pump showed excellent hemodynamic performance with less blood trauma compared with the roller pump in its clinical application to open heart surgery.

Adult↗