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At least 1,225 records · Page 68Linked to original sources
PubMed1996

Clinical comparative study of cardiopulmonary bypass with Nikkiso and BioMedicus centrifugal pumps.

The Nikkiso centrifugal pump was evaluated in elective adult open heart surgery in comparison with the BioMedicus pump. Ten patients using the Nikkiso pump (Group N), and 10 patients using the BioMedicus pump (Group B) were examined for (or to determine) hematobiologic parameters and patient outcome data as well as pump controllability. During cardiopulmonary bypass (CPB), both pumps maintained systemic perfusion satisfactorily without any mechanical adverse event. Rotation speed of the Nikkiso centrifugal pump (3,580 +/- 100 rpm) was significantly higher than that of the BioMedicus pump (3,170 +/- 100 rpm; p < 0.05) whereas changes in free plasma hemoglobin, platelet count, blood urea nitrogen, and creatinine levels showed no significant differences between the two groups. Urine output in Group N for 20 min after the initiation of CPB (7.10 +/- 1.50 ml/kg/h) was significantly higher than that in Group B (3.23 +/- 0.46 ml/kg/h; p < 0.05). Patient outcome data were similar in both groups, such as duration of intensive care unit stay, hospital stay, postoperative intubation time, amount of postoperative bleeding, and amount of blood transfused. These equivalent results with the BioMedicus pump suggested that the Nikkiso pump can be used in open heart surgery as a reliable and atraumatic CPB pump.

Adult↗
PubMed1996

[Solid phase technique versus gel centrifugation for detection of erythrocyte antibodies--a prospective study comparison the 2 antibody detection tests].

AIM: To define differences of specifity and sensitivity between a solid phase- and a gel centrifugation test for detection of irregular erythrocyte antibodies. STUDY DESIGN: 3052 blood samples were screened for erythrocyte antibodies (AB) by gel centrifugation [ID-System, (ID) 37 degrees C Bromelin and indirect antiglobulin test with LISS (IAT)] and a solid phase antiglobulin test [Capture-R Ready Screen (CR)] in a prospective study. Identical test cells were used as immobilized monolayer in CR and as 1%-suspension in ID. Additionally, 42 sera with antibodies reacting in both tests were titered geometrically in both techniques. RESULTS: In 79 (2.6%) of all sera tested, irregular erythrocyte antibodies were detected. 64 (81%) of these positive sera were detected by both tests, 73 (92.3%) by ID and 70 (88.4%) by CR. 6 sera with AB (7.6%) were positive only with CR (1 Ce, 1 E, 1 Leb, 1 C, 1 D, 1 Cob) and 9 (11.4%) only with ID (4 Lea, 1 Fya, 1 C, 2 P1, 1 D). Seven AB solely detected in ID only reacted in the bromelin test, besides an anti-Fya, which was an IgM antibody. The titration of IgG antibodies showed a slightly higher sensitivity of the CR (less than one titre step). The ID showed clearly more unspecific reactions (1.1%) than the CR (0.5%). DISCUSSION: The antibody screening with the ID proved to detect more AB than the CR (mainly due to certainly irrelevant "enzyme only" AB). On the other hand, relevant IgG AB were detected more sensitive by the CR. Unspecific reactions appeared clearly more often in ID, predominantly when using the bromelin test. Missing a strong IgM anti-Fya in the CR is certainly a concern because of its assumed haemolytic activity. Therefore CR for antibody screening should always be combined with a method for crossmatching that safely detects IgM antibodies which are relevant for transfusion.

Blood Group Antigens↗
PubMed1997

Hemolytic effects of surface roughness of a pump housing in a centrifugal blood pump.

The surface roughness of artificial blood contacting devices is an important surface property that is closely related to blood cell trauma. The present study investigated the effect of the surface roughness of a pump housing on hemolysis in an impeller-type centrifugal blood pump, a pivot bearing supported Gyro C1E3 pump. The purpose of the study was to determine which part of a housing has the greatest surface roughness effect on hemolysis in a centrifugal pump. Seven Gyro C1E3 pumps were prepared, each with a smooth surface impeller and a housing with differing areas of altered surface roughness. Both top and bottom housings were divided into half subregions, each with the same area. Seven test pumps were produced by subjecting various subregions of the housings to vapor polishing and sandblasting. The treated surfaces were then examined by a surface profile instrument. Using these 7 pumps with different areas of altered housing roughness, in vitro hemolysis tests were performed simulating cardiopulmonary bypass (5 L/min, 350 mm Hg). The results of this study are as follows. First, the surface roughness of the top housing had a greater effect on hemolysis than that of the bottom housing. Second, on the surface of the top housing, the surface roughness of the outer half area had a greater effect on hemolysis than that of the inner half area. Third, on the surface of the bottom housing, the surface roughness of the inner half area had a greater effect on hemolysis than that of the outer half area. These findings concur with previous studies of flow patterns in pumps. Thus, it is expected that the method in this study, comparative in vitro hemolysis tests of the pumps with surfaces of the same roughness but different locations, can be used to detect the high shear area inside a pump.

Analysis of Variance↗
PubMed1997

Noninvasive prenatal diagnosis. Use of density gradient centrifugation, magnetically activated cell sorting and in situ hybridization.

OBJECTIVE: To develop a noninvasive method suitable for clinical prenatal diagnosis. STUDY DESIGN: Fetal nucleated erythrocytes were separated from peripheral blood of 17 healthy pregnant women using small magnetically activated cell sorting columns (MiniMACS) following density gradient centrifugation and dual antibody labeling methods. The protocol was designed to compare the efficacy of antitransferrin receptor (CD71)/antiglycophorin A (GPA) antibodies with antithrom-bospondin receptor (CD36)/anti-GPA antibodies in identifying nucleated erythrocytes in maternal blood. Cytospin preparations of the isolated cells were subjected to in situ hybridization with specific DNA probes for the Y chromosome and chromosome 21 to confirm the fetal origin. RESULTS: After MiniMACS the enrichment factors for the CD71/GPA- and CD36/GPA-positive cells from maternal blood were similar, and the percentages of fetal cells recovered did not differ. Seven of seven male pregnancies were correctly identified. One case of trisomy 21 was detected. CONCLUSION: The in situ hybridization analysis of fetal nucleated erythrocytes isolated from maternal blood using single density gradient centrifugation, anti-CD71/anti-GPA immunostaining and MiniMACS could be an accurate, sensitive and noninvasive method for prenatal diagnosis.

Cell Separation↗
PubMed1997

Differential flotation centrifugation study of hepatitis C virus and response to interferon therapy.

Hepatitis C virus (HCV) appears to circulate in various forms such as native virion, immune complexes, and nucleocapsids during chronic infections. To determine the association of the physicochemical properties of HCV and its response to interferon therapy in patients with chronic hepatitis C, we examined pretreatment serum samples from 43 patients with HCV RNA who had received interferon therapy, using differential flotation centrifugation in a NaCl solution with a density of 1.063 g/ml. After centrifugation, the ratio of HCV RNA in the top and bottom fractions was determined by the polymerase chain reaction and expressed as T/B. Patients with a sustained response to IFN therapy were found to have higher T/B ratios than transient responders who relapsed after treatment (P < 0.01) and nonresponders (P < 0.01). With regards to HCV genotypes, patients with genotype 1b had higher T/B ratios in the sustained response group than in the nonsustained response groups (P = 0.001), but patients with genotype 2 had a similar distribution of T/B among the 3 response groups (not significant). These findings indicate that the physicochemical properties of HCV affect the effectiveness of interferon therapy, particularly in patients with genotype 1b.

Adult↗
PubMed1977

Separation of cells from mouse solid tumors by centrifugal elutriation.

Centrifugal elutriation was used to separate cells dissociated from two hypotetraploid mouse solid tumors, a fibrosarcoma and a sarcoma derived from L-P59 cells, based on their sedimentation rates. The separation was rapid, requiring less than 1 hr; yielded about 80 percent cell recovery; and resulted in little loss of cell viability. Aanlysis of DNA content by flow cytometry demonstrated the synchrony obtained with these tumor cells. The fractions with the lowest sedimentation rates contained predominantly normal cells, those with intermediate sedimentation rates contained predominantly tumor cells in the G1 phase of the cell cycle, and those with the highest sedimentation rates contained mostly tumor cells in S or G2. The clonogenicity of L-P59 cells, assayed in culture, markedly increased with increasing sedimentation rates. In contrast, the clonogencity of fibrosarcoma cells, assayed in vivo by a lung colony assay, was lower for the smaller cells, but was essentially constant among the larger cells. Autoradiography of cells labeled in vivo with tritiated thymidine demonstrated no differences in the proportions of cycling cells in various fractions. These results demonstrate that subpopulations differing in cell type, phase of the cell cycle, and clonogencity can be rapidly separated from solid tumors by centrifugal elutriation.

Animals↗
PubMedDate not supplied

In vivo evaluation of an extracorporeal pediatric centrifugal blood pump.

This paper summarizes the authors' in vivo experience in evaluating a miniature centrifugal blood pump designed for pediatric/neonatal ventricular support. Left ventricular bypass was accomplished in two adult sheep and five juvenile lambs (5.5-80.0 kg) via either central (left ventricle to carotid artery) or peripheral (jugular vein to carotid artery) cannulation. Animals were weaned from mechanical ventilation and continuously monitored. Hemodynamic parameters remained within a normal range over the duration of the bypass. Two of five lambs were electively killed at 8, and 76 hours; the remaining three lambs died from respiratory complications at 33, 44, and 156 hours. There were no mechanical complications, and blood seal integrity was confirmed beyond 6 days. The pump speed was maintained at 3,000-4,500 rpm with pump flow rates between 0.4-1.5 L/min. Average plasma free hemoglobin was below 20 mg/dl in the five lamb experiments. Renal, hepatic, and hematologic indices also remained within physiologic ranges. Histopathologic analyses of major organs revealed renal cortical infarctions in two of five lambs. Examination of the pump surfaces after explant indicated small areas of thrombus in the housing adjacent to the outflow ports in two experiments. These encouraging results support further testing and refinement of this miniature centrifugal pump.

Animals↗
PubMed1997

Use of Percoll gradient centrifugation for the isolation of diatoms from Wadden Sea sediments; diatom yields, species recoveries and population diversity.

The technique of Percoll gradient centrifugation was applied to samples from Wadden Sea sediments of the shoreside near Dangast (German Bight). Experiments were also performed with Wadden Sea sediment inoculated with diatoms and with axenic and mixed diatom cultures. For axenic and mixed cultures, total recoveries ranged from 6 to 70% of the diatoms loaded onto the gradients, whereas the yields were less than 5% in most of the experiments with Wadden Sea sediments. The extraction of diatoms from mixed cultures and from sediment samples was not quantitative, neither in terms of biodiversity nor of total individuals extracted, because the rates of recovery varied for the different species. Diatom cells extracted by Percoll gradient centrifugation were devoid of sand grains and debris. The obtained material was suitable to be used in biochemical experiments, in cultural studies and for electron microscopy. The overall cell morphology and subcellular organelle organization was excellent and appeared to be unaffected by the purification procedure. The results and advantages and disadvantages of the technique are discussed.

Cell Size↗
PubMed1997

In vivo testing of a magnetically suspended centrifugal pump designed for long-term use.

The life of currently-available centrifugal pumps is limited to no more than three days. As a magnetically suspended centrifugal pump (MSCP) contains no shaft or seal, it could be expected to have a longer life expectancy. The MSCP was evaluated in a chronic animal model using eight adult sheep. Left ventricular assist with the MSCP was instituted between the left atrium and the descending aorta. The flow rates ranged from 2.5 to 6.0 L/min. The duration of the experiments ranged from 14 to 60 days. No mechanical failure occurred. The plasma free hemoglobin levels remained within an acceptable range (3-19 mg/dL). No reduction in the counts of red blood cells or platelets was observed. Thrombus formation within the MSCP was recognized in one pump. The main reason for termination was thromboembolism derived from the circuits. Three types of regulation methods (constant rotational speed, constant motor current, and controlled motor current) were also investigated. Regulation by a constant motor current mode altered the pressure-flow (P-Q) characteristics, and thereby, a steadier pump flow was obtained compared with regulation in the constant rotational speed mode. Moreover, the controlled motor current mode can change the P-Q relationship. These results demonstrate that the MSCP is a promising device for long-term use.

Animals↗
PubMed1998

The "Space Cycle" Self Powered Human Centrifuge: a proposed countermeasure for prolonged human spaceflight.

The Self Powered Human Centrifuge, or Space Cycle, is a countermeasure to the adverse physiologic effects of prolonged human exposure to spaceflight microgravity. This unique device simultaneously provides exercise, impact loading and gravity analogous acceleration to emulate conditions on Earth. One or two crewmembers pedal themselves about a shaft mounted to the space craft located "above" their heads. This creates a short arm centrifuge with a head-to-toe acceleration orientation. The potential advantages of the Space Cycle include: a) reversal of cephalad fluid shift, minimizing post flight orthostatic intolerance; b) pedaling to maintain muscular and cardiovascular fitness; and c) enhancement of skeletal homeostasis by impact loading with a pedal-crank mounted cam and frame mounted resistive device. Other anticipated advantages include generation of usable electricity, physiologic monitoring and a means of mass measurement. Motion sickness is controlled with restraints and virtual reality headsets. The device is compatible with International Space Station dimensional constraints.

Acceleration↗
PubMed1998

Left heart bypass in the pig with a centrifugal pump using cannulae prepared for percutaneous placement.

A rapid and efficient circulatory support system may save a patient in cardiogenic shock. Left heart bypass with percutaneous and trans-septal placement of the aspiration cannula simplifies the circuit and eliminates the need for an oxygenator. In this pre-clinical study we assessed left heart bypass support with a centrifugal pump using new cannulae prepared for percutaneous placement (14 F arterial catheter and 16 F left atrial aspiration line) in 5 anaesthetized pigs. Animals were supported for two hours at a mean flow of 3.2 l/min (4,033 rpm), a mean haematocrit of 29% and low heparinisation (ACT double baseline). Hemodynamic measurements and blood samples were taken at baseline (A), 10 minutes (B), one hour (C) and 2 hours (D) on support. Results show maintenance of hemodynamic parameters throughout the 2 hour support period. Only systolic arterial and left ventricular pressure decreased by 12% and 20% respectively from baseline to the end of the support period with a 13% increase in cardiac output. When the pump was turned on (0-3 l/min) there was usually a decrease in heart rate, systolic pressure and left ventricular pressure, with unchanged cardiac output (non failing model). Potassium increased from 3.9 to 4.2 mmol/l (ns), and plasma hemoglobin from 6.0 to 18.2 mg/dl (p<0.05). Thrombocytes decreased from 187 to 155 10(9)/l (ns). In conclusion, this preclinical study demonstrated the feasibility of an efficient left heart bypass of short duration with a centrifugal pump using cannulae prepared for percutaneous placement. Left heart bypass was well tolerated hemodynamically and no significant laboratory change occurred within the two hours of support. This opens several possibilities for the short term support of patients in cardiogenic shock and eventually also for patients submitted to minimally invasive cardiac surgery.

Animals↗
PubMed1998

[Osmotic fragility test of erythrocytes with a coil planet centrifuge].

The measurement of osmotic fragility of erythrocytes has been applied to the diagnosis of hemolytic diseases, studies of membrane permeability and alternations leading to destruction of erythrocytes. Almost 30 years have gone by since the coil planet centrifuge system was devised for measuring the osmotic fragility of erythrocytes. Many excellent studies by means of this centrifuge system have been published. Prominent investigations are reviewed as follows: in relation to the osmotic fragility, various liver diseases, angina pectoris, trapping the aged erythrocytes, tumor, lactic acid, unsaturated fatty acids, free cholesterol, exercise and lead exposure level were examined.

Angina Pectoris↗
PubMed1998

Comparative analysis between centrifuged hematocrit and "point-of-care" hemoglobin: impact on erythropoietin dosing.

The purpose of this CQI project was to examine the degree of anemia among our dialysis population and compare centrifuged hematocrits (HCTs) with point-of-care HemoCue hemoglobin (HGB) for accuracy and to assess any differences in patient outcomes. It was concluded that the point-of-care HemoCue HGB was more accurate than the centrifuged HCT when compared to the laboratory method. It was further concluded that accurate weekly results facilitated more appropriate patient EPO dosages, which in turn influenced patient outcomes.

Anemia↗
PubMed2004

Centrifugal visual system of Crocodylus niloticus: a hodological, histochemical, and immunocytochemical study.

The retinopetal neurons of Crocodylus niloticus were visualized by retrograde transport of rhodamine beta-isothiocyanate or Fast Blue administered by intraocular injection. Approximately 6,000 in number, these neurons are distributed in seven regions extending from the mesencephalic tegmentum to the rostral rhombencephalon, approximately 70% being located contralaterally to the injected eye. None of the centrifugal neurons projects to both retinae. The retinopetal neurons are located in rostrocaudal sequence in seven regions: the formatio reticularis lateralis mesencephali, the substantia nigra, the griseum centralis tectalis, the nucleus subcoeruleus dorsalis, the nucleus isthmi parvocellularis, the locus coeruleus, and the commissura nervi trochlearis. The greatest number of cells (approximately 93%) is found in the nucleus subcoeruleus dorsalis. The majority are multipolar or bipolar in shape and resemble the ectopic centrifugal visual neurons of birds, although a small number of monopolar neurons resembling those of the avian isthmo-optic nucleus may also be observed. A few retinopetal neurons in the griseum centralis tectalis were tyrosine hydroxylase (TH) immunoreactive. Moreover, in the nuclei subcoeruleus dorsalis and isthmi parvocellularis, both ipsilaterally and contralaterally, approximately one retinopetal neuron in three (35%) was immunoreactive to nitric oxide synthase (NOS), and a slightly higher proportion (38%) of retinopetal neurons were immunoreactive for choline acetyltransferase (ChAT). Some of them contained colocalized ChAT and NOS/reduced nicotinamide adenine dinucleotide phosphate-diaphorase. Fibers immunoreactive to TH, serotonin (5-HT), neuropeptide Y (NPY), or Phe-Met-Arg-Phe-amide (FMRF-amide) were frequently observed to make intimate contact with rhodamine-labeled retinopetal neurons. These findings are discussed in relation to previous results obtained in other reptilian species and in birds.

Alligators and Crocodiles↗
PubMed1976

Olfactory relationships of the telencephalon and diencephalon in the rabbit. III. The ipsilateral centrifugal fibers to the olfactory bulbar and retrobulbar formations.

The axoplasmic retrograde transport of horseradish peroxidase (HRP) from axon terminals to their parent cell bodies and histochemical fluorescence microscopy have been used to study the ipsilateral centrifugal fibers to the olfactory bulbs and anterior olfactory nucleus in the rabbit. Focal injections of peroxidase were placed unilaterally into the main or accessory olfactory bulb or into the anterior olfactory nucleus. In animals with injected HRP confined within the main bulb, perikarya retrogradely labeled with the protein in the ipsilateral forebrain were observed in the anterior prepyriform cortex horizontal limb of the nucleus of the diagonal band, and far lateral preoptic and rostral lateral hypothalamic areas. Brain stem cell groups that contained HRP-positive somata include the locus coeruleus and midbrain dorsal raphe nucleus. Except for the prepyriform cortex, the basal forebrain structures with labeled perikarya correlate well with locations of cell bodies containing acetylcholinesterase and choline acetyltransferase. These somata may represent a cholinergic afferent system to the main olfactory bulb. Peroxidase-labeled cell bodies in the locus coeruleus and midbrain raphe are indicative of noradrenergic and serotonergic innervations respectively of the olfactory bulb. In rabbits in which peroxidase was injected or diffused into the accessory olfactory bulb and anterior alfactory nucleus, HRP-positive somata were identified in the prepyriform cortex bilaterally, the horizontal limb of the diagonal band nucleus, lateral hypothalamic region, nucleus of the lateral olfactory tract, corticomedial complex of the amygdala, mitral and tufted cell layers of the ipsilateral main olfactory bulb, locus coeruleus, and the midbrain raphe. Evidence for centrifugal fibers to the accessory olfactory bulb from the corticomedial complex of the amygdala, locus coeruleus, and possibly the nucleus of the lateral olfactory tract and midbrain raphe is discussed. A similar distribution of labeled perikarya in the forebrain and brain stem was seen in rats in which peroxidase injected into the main olfactory bulb had spread into the accessory bulb and anterior olfactory nucleus. Histochemical fluorescence microscopy of the main and accessory olfactory bulbs in the rabbit and rat revealed fine caliber, green fluorescent fibers and varicosities predominantly in the granule cell layer and less so among cells in the glomerular layer. In sections through the root of the main olfactory bulb, a similar fluorescence was seen in the deep half of the plexiform layer of the pars externa of the anterior alfactory nucleus. These fluorescent fibers likely represent the noradrenergic innervation of the olfactory bulbar and retrobulbar formations. A fluorescent yellow hue was observed in the glomerular layer of the main bulb and may signify a serotonergic innervation of this lamina...

Animals↗
PubMed1995

Comparison of diametral shrinkage of centrifuged and uncentrifuged Simplex P bone cement.

Reducing the porosity of bone cement substantially strengthens the cement in fatigue. However, concern has been raised that reducing the porosity of the cement would increase the shrinkage of the cement and thus compromise the cement-bone interface. We measured diametral shrinkage of cement mantles prepared with and without centrifugation of the cement. Four cement preparations (centrifuged and uncentrifuged mixed with monomer at either room temperature or 0 degrees C) were used to form cement mantles of four different thicknesses (2, 4, 6, and 8 mm) around a stainless steel rod. We conclude that porosity reduction dramatically increases the fatigue strength of bone cement without substantially changing the diametral dimensions of the polymerized cement when studied in the shape and volume of a cement mantle that would be used for total hip replacement.

Biocompatible Materials↗
PubMed1994

The interaction of calmodulin and polylysine as studied by 1H NMR spectroscopy and sedimentation equilibrium centrifugation.

The effects of polylysine on calmodulin were assessed using 1H NMR and sedimentation equilibrium centrifugation. Sedimentation equilibrium centrifugation measurements demonstrated that calmodulin associates with polylysine at calmodulin-polylysine molar ratios ranging from 10:1 to 2.5:1 and when polylysine is increased above the molar ratio of 1:1 a precipitate is formed. At a 1:2.5 calmodulin:polylysine molar ratio, 75% of the calmodulin precipitates from the solution and virtually no polylysine is present in the precipitate. 1H NMR studies of the aromatic region of calmodulin identified chemical shifts of three peaks at a calmodulin:polylysine molar ratio of 1:1. These studies suggest that polylysine associates with calmodulin in aqueous solution and can alter the structure of calmodulin to cause calmodulin self-aggregation.

Animals↗
PubMed1990

Saccade-related responses of centrifugal neurons projecting to the chicken retina.

Centrifugal projections to several sensory systems modulate the afferent activity during active behaviors. To see whether such modulation occurred in the visual system, we recorded the activity of isthmo-optic neurons in awake chickens during eye movements. We find that the discharge of all isthmo-optic neurons tends to stop during saccades, although every neuron does not pause for every saccade. The pause begins at approximately the same time as the saccade, and pause duration is correlated with saccade duration. Pausing during saccades occurs in both dark and light suggesting that it is motoric rather that visual in origin. In addition, we find that the spontaneous activity of isthmo-optic neurons increases in darkness. We discuss the significance of the saccadic modulation of isthmo-optic activity in terms of possible functions of the centrifugal projection in modulation of ganglion cell activity.

Animals↗