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PubMed1999

Evaluation of a portable differential continuous flow centrifuge for concentration of Cryptosporidium oocysts and Giardia cysts from water.

A portable device was developed and assembled from a stationary differential continuous flow centrifuge usually employed for blood cell separation, for the purpose of concentrating Cryptosporidium and Giardia from large volumes of water. Following compaction onto the wall of the disposable plastic centrifuge bowl and aspiration of residual water, the oocysts and cysts were dislodged by injection of a 20 ml solution containing 0.01% Tween-80 and 1% SDS and vigorous shaking. Following aspiration, the oocysts were pelleted, reacted with specific FITC-conjugated monoclonal antibodies, and enumerated via fluorescence microscopy. The entire procedure required about 2 h. Initially, 55% and 87% of Cryptosporidium oocysts and Giardia cysts, respectively, were recovered from 45 litres of tap water, and 27% and 57%, respectively, from river water. Adjustments in centrifuge speed and flow rates improved recovery to about 90% for Cryptosporidium oocysts and hence, this method compared favourably with the recently developed calcium carbonate flocculation method. It was superior in time requirement and volume flexibility, and showed a distinct advantage over the standard cartridge filtration method in all respects. The continuous flow centrifugation equipment is compact, mobile, flexible, and yields reproducibly high recovery rates. The ease of handling, speed of performance and minimal requirements for post-concentration equipment, reagents and labour make the system highly cost-effective. It appears to offer an improved method, well suited for use by water utilities for monitoring the burden of water-borne protozoan pathogens.

Animals↗
PubMed1998

Afterload-dependent flow fluctuation of centrifugal pump: should it be actively fixed?

To evaluate the clinical meaning and effects of afterload-dependent flow fluctuation in a centrifugal pump, concomitant measurement of flow rate and mixed venous oxygen saturation (SVO2) was performed in 5 cases of open heart surgery in which the patients underwent cardiopulmonary bypass (CPB) with the Terumo Capiox centrifugal pump. Continuous measurement of SVO2 using the 3M CDI System 100 was performed with a disposable cuvette incorporated into the drainage circuit. After the target flow rate of 2.4 L/min/m2 was obtained under a nonbeating condition, the pump rotational speed was fixed. During the cooling and low temperature period, SVO2 decreased as the flow rate spontaneously decreased but still stayed around 80% even with a 15-20% decrease in blood flow rate. This indicates that a luxury perfusion condition is ensured as long as the body temperature is kept low. In contrast, during the rewarming period, SVO2 decreased to around 70-75% despite a 15-25% spontaneous increase in flow rate. Although this level of SVO2 still indicates adequate systemic perfusion, there is a possibility of regional hypoperfusion in patients with such conditions as cerebrovascular disease. In conclusion, although diligent adjustment of the physiological fluctuating flow rate in the centrifugal pump seems unnecessary during conventional open heart surgery, manual control may be necessary especially during the rewarming period, normothermic surgery, or circulatory assist for shocked patients. From this study, we also conclude that the major benefit of the afterload-independent autoflow control system of the centrifugal pump is the improvement of safety in terms of the fixed reservoir level and the handling of cardiopulmonary bypass.

Blood Flow Velocity↗
PubMed2000

Development of a compact, sealless, tripod supported, magnetically driven centrifugal blood pump.

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.

Centrifugation↗
PubMed2002

Centrifugal blood pumps for various clinical needs.

During the past 10 years, different types of blood pumps were developed to address various clinical needs. The Nikkiso centrifugal blood pump was developed for cardiopulmonary bypass application. This blood pump has been widely used in Japan in more than 20% of the cardiopulmonary bypass procedures. The Kyocera C1E3 Gryo pump was developed for short-term circulatory assistance and extracorporeal membrane oxygenation application for up to 2 weeks. This blood pump has been clinically used for up to 28 days without any blood clot formation. Through Phase I of the Japanese government New Energy and Industrial Technology Development Organization (NEDO) program, a chronically implanted centrifugal pump for left ventricular assistance was developed. This pump has already demonstrated its effectiveness, safety, and durability as a 2 year blood pump through in vitro and in vivo experiments. Currently, it is in the process of being converted from an experimental to a clinical device. Through Phase II of the NEDO program, a permanently implantable biventricular assist centrifugal blood pump system is under development. It has demonstrated that the previously mentioned left ventricular assist device blood pump is easily converted into a right ventricular assist pump by simply adding a spacer between the pump and the actuator. This communication discusses the historical development strategies for centrifugal blood pumps and their current status for different clinical needs.

Cardiovascular Diseases↗
PubMedDate not supplied

Optimum centrifugation conditions for the preparation of platelet and plasma products.

Units of whole blood were centrifuged for various periods of times and at various speeds to prepare platelet-rich plasma. It was found that several sets of centrifugation conditions resulted in an optimum yield of platelets and plasma. This optimum was approximately 8.3 x 10(10) platelets in 245 ml of plasma. When platelet-rich plasma was centrifuged, a maximum of approximately 95 per cent of the platelets could be recovered in the concentrate. Although this maximum was also achieved by several sets of centrifugation conditions, the most efficient method was 3,800 RPM (3731 x g) for four minutes at speed.

Blood Cell Count↗
PubMed2002

Detection and quantitation of ABO RBC chimerism by a modified coil planet centrifuge method.

BACKGROUND: Differential agglutination procedures and flow cytometric analysis have been used for detecting and quantitating mixed cell populations. For more than 20 years in our laboratory, a differential agglutination method using the coil planet centrifuge and polyclonal anti-A or anti-B has been used. However, it is now difficult to obtain polyclonal antisera, and it is unknown whether MoAbs can take the place of polyclonal antisera in the coil planet centrifuge method. STUDY DESIGN AND METHODS: Polyclonal antisera and MoAbs were filled into a coil first and then unsensitized packed RBCs from ABO variants, and from chimeras and patients after ABO-incompatible HPC trans- plantation (HPCT) were loaded. After centrifugation, agglutinated and nonagglutinated RBCs were collected, hemolyzed, and subjected to colorimetric analysis for quantitation. RESULTS: ABO chimerism was quantitatively estimated with detection as low as 0.1 percent. ABO variants showed different patterns of agglutination and nonagglutination. The reconstitution status of the erythroid lineage after ABO-mismatched HPCT was also quantitatively evaluated. CONCLUSION: A modified coil planet centrifuge method is established by which ABO chimerism could quantitatively be analyzed and ABO variants identified to the same degree of accuracy as the other differential methods and flow cytometry. The monitoring of ABO chimerism might also help the diagnosis of early relapse or rejection after ABO incompatible HPCT.

ABO Blood-Group System↗
PubMed2002

Differences in bone-cement porosity by vacuum mixing, centrifugation, and hand mixing.

The mean pore size and percent porosity of vacuum-mixed cement were compared with centrifuged cement and cement hand mixed by skilled specialized operating room technicians. Centrifuged cement samples had the smallest mean pore size when compared with vacuum-mixed specimens. The mean pore size for the hand-mixed specimens was intermediate and not significantly different from the other 2 mixing techniques. Results were reversed, however, for mean percent porosity. Centrifuged cement had the highest percent porosity; vacuum-mixed cement, the lowest; and hand-mixed cement, intermediate. The porosity of vacuum-mixed Simplex P (Howmedica, Rutherford, NJ) bone-cement was similar from the initial to the remnant cement extruded from the cement gun. There was no reduced cement porosity with vacuum mixing or centrifugation as anticipated. Reversion to hand mixing by highly skilled technicians could result in a significant cost savings without negative effects on cement porosity.

Bone Cements↗
PubMed2000

Evaluation of the centrifuged and Gram-stained smear, urinalysis, and reagent strip testing to detect asymptomatic bacteriuria in obstetric patients.

OBJECTIVE: Our purpose was to compare the efficacy of the centrifuged and Gram-stained smear with the efficacy of both urinalysis and reagent strip testing for nitrites and leukocyte esterase in detecting asymptomatic bacteriuria in obstetric patients. STUDY DESIGN: A midstream urine specimen was evaluated in 528 patients either at the initial prenatal visit or at a visit because of possible preterm labor. Separate aliquots were tested by centrifugation (with a Cytospin Cytocentrifuge; Shandon, Inc, Pittsburgh, Pa) with Gram stain, by microscopic urinalysis for the presence of moderate to large numbers of bacteria or >10 leukocytes per high-power field, and by reagent strips for the presence of nitrites or leukocyte esterase activity. Results were compared with those of a quantitative urine culture obtained with blood and MacConkey agar plates. RESULTS: Thirty-six women (6.8%) had urine cultures showing 100,000 colony-forming units of a uropathogen per milliliter. The sensitivity and specificity of testing by centrifugation and Gram stain were 100% and 7.7%, respectively. Urinalysis and dipstick testing offered a sensitivity of 80.6% and 47.2%, respectively, with a specificity of 71.5% and 80.3%. No combination of tests, in series or in parallel, offered improved specificity over urinalysis alone. CONCLUSIONS: Centrifugation with Gram stain of a urine specimen offers excellent sensitivity but very poor specificity compared with microscopic urinalysis for the detection of asymptomatic bacteriuria and is not an acceptable screening test in an obstetric population. The false-negative rates of urinalysis (19.4%) and reagent strip testing (52.8%) preclude these from being excellent screening tests for asymptomatic bacteriuria. Given the potential sequelae of undiagnosed asymptomatic bacteriuria in an obstetric population, we conclude that urine cultures should be used for all pregnant patients to detect asymptomatic bacteriuria.

Adolescent↗
PubMed1969

Intracellular centrifugal separation of organelles in Phycomyces.

Live sporangiophores of Phycomyces blakesleeanus were centrifuged at 35,000 rpm. The cell contents sedimented into distinct layers, and each layer was studied with an electron microscope and with cytochemical methods. The following layers were found (their volumes and their densities are shown in Fig. 3): 1. polyphosphates; 2. polyphosphates and protein crystals; 3. glycogen; 4. yellow layer with ferritin; 5. ribosomes; 6. protein crystals; 7. mitochondria; 8. mitochondria and fibrils; 9. nuclei; 10. endoplasmic reticulum; 11. vesicles, membranes, and reticulum; 12. vacuole; 13. lipoproteins, membranes; 14. fat droplet. The densities of the various layers were determined by the injection of droplets of inert oils of known density into the sporangiosphores before centrifugation. Sedimented cell organelles could be isolated. Centrifuged nuclei of a lycopene-producing mutant were injected into the intact sporangiophore of an albino host where they induced color formation. The ensuing spores, when plated, gave a mixture of white and colored colonies. It was concluded that cell organelles, sedimented by centrifugation of living sporangiophores, remain alive and can be used for biochemical studies. Microspectrophotometric examination of the layers indicated the presence of cytochromes and flavines in the mitochondria and of cytochromes in the nuclei. No pigments corresponding to the action spectrum for the light growth response were found.

Cell Biology↗
PubMed1972

Separation of HeLa cells by colloidal silica density gradient centrifugation. I. Separation and partial synchrony of mitotic cells.

Using a colloidal silica density gradient, HeLa cells in mitosis were found to have a density of 1.040-1.046 g/cc, lighter than the remaining interphase cells. The mitotic cells could be harvested and cultured after centrifugation, showing growth synchrony by measurement of a peak in mitotic index 21 hr after establishing the culture. By using Colcemid or vinblastine sulfate, HeLa cells were arrested in metaphase and centrifuged on the colloidal silica density gradient. The blocked metaphase cells were lighter in density than the interphase cells but somewhat more dense than untreated cells selected by the density gradient centrifugation. Near-equilibrium conditions were established during the centrifugation of cells so that cell density measurements could be made, and the gradient medium employed was not measurably toxic to those cells tested.

Cell Separation↗
PubMed1998

Quantitation of cocaine in human hair: the effect of centrifugation of hair digests.

Hair pigmentation is a critical factor in the interpretation of the concentration of certain compounds and their metabolites incorporated into hair. Melanin is responsible for the pigmentation. The color and the melanin content of human hair samples differs over a wide range. Once deposited into hair, drug may remain detectable for a period of months to years. However, if drug disposition into hair is influenced by those properties attributed to hair color, then certain persons may test positive more frequently than other persons. Removal of the melanin from hair digests prior to drug analysis may reduce the effect of melanin on the total drug concentration by excluding the drug bound to the pigment. In this study, the effect of melanin removal by centrifugation of hair digests on cocaine concentrations was investigated. Two sets of hair samples from five cocaine users were analyzed for cocaine and metabolites. A solution consisting of 10 mL of 0.5M Tris buffer (pH 6.4) to which is added 60 mg D,L-dithiothreitol, 200 mg SDS, and 200 U Proteinase K, was used to digest the hair. Two milliliters of this solution was added to 20 mg of hair and incubated at 37 degrees in a shaking water bath (90 oscillations/min) overnight. The samples were removed from the water bath and mixed. One set was centrifuged at 2000 rpm and divided into supernatant and melanin pellet. The other set was not centrifuged. Internal standards were added to all tubes. The samples were further extracted, derivatized, and analyzed by gas chromatography-mass spectrometry. A mean of 8.8% (standard deviation [SD] 7.0%) of the total cocaine concentration (supernatant and pellet) was left behind in the pellet. The same experiment was repeated except that the melanin pellet was redigested with 0.1 N HCl. After redigestion of the melanin pellet, the mean cocaine concentration in the pellet was 3.8% +/- 4.0% (mean +/- SD) of the total cocaine concentration in hair. These data demonstrate that removal of melanin from hair digests by centrifugation does not eliminate hair color bias when interpreting cocaine concentrations.

Centrifugation↗
PubMedDate not supplied

Optimization of EMIT reagent system using a COBAS-BIO centrifugal analyzer.

An optimized method for application of the EMIT reagent system to a COBAS-BIO centrifugal analyzer was developed to minimize reagent consumption while maintaining good precision and accuracy. Forty-one serum samples, previously analyzed for theophylline by HPLC, were assayed using the modified protocol on the COBAS-BIO centrifugal analyzer. Regression analysis of the results obtained from both methods yielded the following equation: y = 1.10x + 0.01, r = 0.964 (x = HPLC, y = COBAS-BIO centrifugal analyzer, EMIT). The COBAS-BIO centrifugal analyzer and EMIT methodology provided an efficient, inexpensive, and relatively effortless approach to drug monitoring in the routine clinical laboratory.

Anticonvulsants↗
PubMed1998

Transfer of sperm into a chemically defined environment by centrifugation through 12% (wt/vol) Accudenz.

Centrifugation is commonly used to wash sperm; however, most washing techniques do not put sperm in a chemically defined environment. Rather, washing by centrifugation, in effect, dilutes seminal plasma components. A 0.5-mL volume of 30% (wt/vol) Accudenz was layered beneath 5 mL of 12% (wt/vol) Accudenz in a 15-mL polypropylene centrifuge tube. Diluted semen from individual males (n = 10) was overlaid upon the 12% (wt/vol) Accudenz. After centrifugation at 1,250 x g at 4 C for 25 min, washed sperm were present at the interface of the Accudenz layers. Based upon hemacytometer counts, sperm recovery was 83% (CV = 12%). Neither sperm viability nor morphology was affected by washing. Efficacy of the washing procedure was evaluated by using extracellular glucose, glutamic acid, Ca+2, and protein as markers. Washing eliminated 99% of the glutamic acid and glucose associated with sperm. Likewise, washing removed 98.5% of the extracellular Ca+2 associated with sperm. As evidenced by total protein analysis and SDS-PAGE, washing removed 98% of soluble seminal plasma proteins from sperm. In addition, washing did not affect sperm mobility or fertilizing ability. This procedure returns extended sperm to a physiological concentration in a chemically defined environment. By suspending washed sperm in distinct media, we induced differential sperm mobility. Therefore, this procedure is suitable for the study of the effect of specific substances upon sperm cell function.

Analysis of Variance↗
PubMed1987

Functional and physical characteristics of rat Leydig cell populations isolated by metrizamide and Percoll gradient centrifugation.

The physical and functional properties of Leydig cell populations obtained by centrifugation of testicular cells in two different density gradient media, Percoll and Metrizamide, were compared. Percoll-gradient centrifugation yielded two Leydig cell bands (Peak I and Peak II) that were comparable, as to their density and testosterone-producing capacity, to the respective Leydig cell bands, Population I and Population II, isolated in a Metrizamide gradient. The denser Leydig cell band (II) had a greater capacity for testosterone production than the less dense band (I), regardless of the type of gradient used for its isolation. Metrizamide gradient centrifugation separated the majority of germ cells from the "light" (Population I) Leydig cells, whereas in the Percoll gradient, germ cells comigrated with Peak I Leydig cells. Leydig cell separation by Percoll gradients was highly dependent on the presence of Ca2+ and Mg2+ in the medium, while these cations had no effect on the separation of Leydig cells by Metrizamide. In conclusion, Metrizamide gradient centrifugation yielded two Leydig cell populations of similar functional and physical properties to the respective populations isolated in Percoll gradients.

Animals↗
PubMedDate not supplied

Effect of surface roughness on hemolysis in a centrifugal blood pump.

Surface roughness of a blood pump is an important factor for blood cell damage. This study investigated the effect of surface roughness pertaining to hemolysis in a centrifugal pump. In vitro hemolysis tests were performed under cardiopulmonary bypass (CPB; 5 L/min, 350 mmHg) and left ventricular assist device (LVAD; 5 L/min, 100 mmHg) conditions using the pivot bearing supported Gyro centrifugal pump (C1E3). Seven types of pumps with impellers and housings with different surface roughness were prepared as follows: vapor polish (VP) housing and VP impeller; VP housing and sandpaper (SP) impeller; VP housing and fine sandblasting (FSB) impeller; VP housing and coarse sandblasting (CSB) impeller; SP housing and VP impeller; FSB housing and VP impeller; and CSB housing and VP impeller. The results revealed that 1) the effect of surface roughness on hemolysis was significantly larger with CPB than LVAD; 2) surface roughness, regardless of the impeller or housing, had little effect on hemolysis with LVAD; and 3) during CPB, the surface roughness of the pump housing had a larger effect on hemolysis than did that of the impeller. In conclusion, from a hemolytic point of view, it is likely that an extremely smooth pump housing is required for an impeller centrifugal pump for CPB. However, it is likely that a smooth surface is not as essential for this impeller centrifugal pump as for an LVAD.

Animals↗
PubMedDate not supplied

Long-term ex vivo bovine experiments with the Gyro C1E3 centrifugal blood pump.

Centrifugal blood pumps are used widely for cardiopulmonary bypass, as ventricular assist devices, and for extracorporeal membrane oxygenation (ECMO). However, there is no centrifugal blood pump that is suitable for long-term ECMO. The authors developed the Gyro C1E3 centrifugal blood pump (Kyocera Corporation, Kyoto, Japan), which has superior antithrombogenic, antitraumatic, and hydraulic features in comparison with the conventional centrifugal blood pumps. Five ex vivo long-term durability tests of the Gyro C1E3 were performed using healthy miniature calves. The ECMO circuit was composed of a prototype hollow fiber silicone membrane oxygenator and a Gyro C1E3 pump. Venous blood was drained from the left jugular vein of a calf, passed through the oxygenator and infused into the left carotid artery using a Gyro C1E3. Ex vivo studies were performed from 7 to 15 days at a blood flow rate of 1 L/min. During this period, the Gyro C1E3 demonstrated a stable performance without exchanging the pump. Bleeding complications were the major reason for termination of each experiment. Rotational speed was maintained around 2,000 rpm. All five calves demonstrated neither abnormal signs nor abnormal blood examination data throughout the experiment. Neither clot nor thrombus formations were found during the necropsy in the cannula or pump nor were infarctions observed in any of the major organs. In conclusion, the Gyro C1E3 showed a stable and reliable performance during long-term ex vivo bovine experiments under the conditions tested.

Animals↗
PubMed1984

Separation of human bone marrow by counterflow centrifugation monitored by DNA-flowcytometry.

Human bone marrow was fractionated by counterflow centrifugation into 16 fractions with increasing cell size. Three distinct subpopulations could be recognized: small lymphocytic cells, medium-sized nucleated erythroid cells and large myeloid elements. DNA-flowcytometry and 3H-thymidine uptake showed that within the erythroid and myeloid cell populations counterflow centrifugation separates each population according to the cell cycle phase. Hypotonic treatment of bone marrow for removal of the erythroid nucleated cells resulted in a complete abrogation of the proliferating erythroid cell population. Counterflow centrifugation also separates the small non-proliferating myeloid and erythroid committed stem cells from the larger proliferating stem cells. It appeared feasible to separate the small lymphocytic cells from the majority of BFU-E and CFU-GM, due to the larger size of the proliferating normoblasts and the committed progenitor cells. Elimination of the mature lymphocytes from the haematopoietic stem cells by counterflow centrifugation may offer an alternative approach to the prevention of graft versus host disease (GvHD).

Bone Marrow↗
PubMed1978

Effect of centrifugation and subsequent storage on red blood cells.

Blood drawn into CPD solution from 33 normal donors was divided into four groups: (I) centrifuged (at 5,000 g for 7 min) after 7 days of storage, (II) centrifuged after 14 days storage, (III) centrifuged after 21 days storage and (IV) uncentrifuged. After 21 days of storage, aliquots of all units were labeled with chromium-51, reinjected into the donor from which they were drawn and erythrocyte survival was measured. Red blood cell recovery and survival for all four groups was essentially the same; 24-hour recovery was 85%; T 1/2 was 28.2--31.6 days. Our results suggest that blood can be centrifuged and stored at any time during its 21-day shelf life without detrimental effect on erythrocyte survival.

Adult↗