Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CENTRIFUGATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,369 records · Page 76Linked to original sources
PubMed1990

[The centrifugal pump--a new method of assisting the failing heart following open heart surgery].

The centrifugal pump is a new mechanical ventricular assistant device, which is used to help the failing heart after cardiopulmonary bypass or postoperatively in the ICU. The centrifugal pump is hemodynamically able to improve the coronary and peripheral perfusion in patients in cardiogenic shock. The pump can displace the entire cardiac output and let the blood bypass the left ventricle, which gives the failing heart a possibility for metabolic correction and regeneration. Ten patients were included in the early personal experience at the cardio-thoracic unit in Edinburgh, with a survival rate of 50%, which is regarded as being very satisfactory. All hemodynamic parameters were normalised in the surviving patients.

Aged↗
PubMed1990

[Surgical treatment of descending thoracic aortic aneurysm under temporary bypass with antithrombogenic tube and bio-medicus centrifugal pump].

Four patients with descending thoracic aortic aneurysm were successfully operated on under temporary bypass with an antithrombogenic tube and a Bio-Medicus centrifugal pump. The bypass flow ranged from 1.0 to 2.4 l/min with the mean femoral artery pressure of 50 to 70 mmHg. No complications such as paraplegia, hepatic dysfunction or renal failure were encountered in all the patients. Temporary increment of the serum amylase level occurred in all the patients, but any apparent clinical symptoms were not present. The temporary bypass method with an antithrombogenic tube and a centrifugal pump is useful and reliable for surgical treatment of descending thoracic aortic aneurysm.

Aged↗
PubMed1989

Prolonged ventricular support using a centrifugal pump.

The Biomedicus centrifugal pump was required to provide prolonged ventricular support to 13 patients with hemodynamic instability: 11 after cardiovascular surgical procedures, 1 after myocardial infarction and 1 after failure of a heart transplant. The duration of support ranged from 3.5 hours to 9 days (mean 72 hours). Complications included bleeding in six patients, renal insufficiency in three and central nervous system deficit in three. Six patients (46%) were successfully weaned from the pump. The patient with graft failure had hyperacute rejection of a second heart. Five patients were discharged from the hospital. There was one death 8 months postoperatively. Prolonged ventricular support with the centrifugal pump may allow recovery of potentially reversible ventricular dysfunction in selected patients after cardiac surgical procedures.

Adolescent↗
PubMed1989

Countercurrent centrifugal elutriation. High-resolution method for the separation of growth-plate chondrocytes.

Countercurrent centrifugal elutriation was used to separate, on the basis of size, isolated growth-plate chondrocytes in chicks. The mean cellular volume, activity of alkaline phosphatase, and synthesis of type-X collagen increased progressively in each of seven successive fractions. Slices of tissues that contained either proliferating or hypertrophic chondrocytes were also removed by manual dissection from the superficial and deep regions of the growth plate. These cells demonstrated differences in size and biochemistry that were similar to those observed in chondrocytes that were separated by elutriation. These differences included increased synthesis of proteoglycan and collagen in the larger chondrocytes. Radiolabeled hypertrophic chondrocytes were mixed with unlabeled resting and proliferating chondrocytes, and then were separated by elutriation. The radioactivity was recovered in fractions that contained the largest cells, confirming that differences in the sizes of the cells can be used to effect a zonal separation by centrifugal elutriation.

Alkaline Phosphatase↗
PubMed1989

[A case of biventricular assist with centrifugal pumps after operation of ventricular septal perforation following acute myocardial infarction].

We applied biventricular assist using centrifugal pumps on a 64-year-old male who has undergone an operation against post-myocardial infarction with ventricular septal perforation. The pump flow was maintained at the level of 2.5 l/m2 in CI, and the pulse pressure 30 to 50 mmHg with IAPB. Complete hemostasis has been achieved prior to use heparin to control the patient's ACT around 200 sec. on the third pumping day. The patient's cardiac function improved in a few days at the beginning, but did not recover enough for weaning from the assist devices. He died on the 8th pumping day, and the autopsy revealed massive old myocardial infarction which is considered to be the major obstacle against the recovery of the cardiac function. There was no edema in any organs. Centrifugal pumps are very useful for ventricular assist in availability and in economy. Its efficacy is comparable with pulsatile ventricular assist devices especially when applied with IABP though there still exists controversy as for the superiority of pulsatile flow in ventricular assist.

Assisted Circulation↗
PubMed1987

[Demonstration of centrifugal fibers in the optic chiasma and optic nerves in the rat after lesions of the suprachiasmatic nucleus].

After an unilateral destruction of the suprachiasmatic nucleus and with the use of several silver impregnation techniques, degenerating centrifugal fibers were found in both optic nerves. Centrifugal fibers to the retina originate from three different regions of the nucleus and their position in the chiasma are different. In large majority the degenerating fibers were located at the periphery of the optic nerve and were more frequent on the contralateral than on the ipsilateral side to the destroyed suprachiasmatic nucleus. The possibility that our experimental procedure demonstrates the existence of fibers originating not only in the suprachiasmatic nucleus but also in other structures whose efferent fibers pass at this level, is discussed.

Animals↗
PubMed1988

Kinematics of centrifugal and centripetal saccadic eye movements in man.

The kinematics of centrifugal and centripetal saccadic eye movements were quantified in human subjects. The maximum velocity of centripetal saccades increased with the eccentricity of the orbital starting point and was systematically higher than that of centrifugal saccades starting from primary orbital position. The slope of this linear increase was related to target step amplitude (2.6 and 3.9 deg/sec/deg for 20 and 30 deg, respectively). Despite these velocity changes, saccade amplitude was maintained by corresponding variations of the duration of deceleration. These findings, which are relevant with respect to saccadic control theories, indicate that initial eye position must be considered before comparing saccades based on their kinematic properties.

Adaptation, Ocular↗
PubMedDate not supplied

Centrifugal extension of coronary intimal necrotic areas.

The use of serial cross-sections, camera lucida drawings and photographic reconstruction of longitudinally cut samples, revealed that about half of intimal necrotic areas present in the coronary arteries of subjects aged 41-50 years exhibited a longitudinal diameter greater than 1.0 cm, occurring as very long lesions. In the 16 intimal necrotic areas included in a tridimensional study the longitudinal diameter was 7.8 times greater than the transverse one and 11.3 times greater than the luminal-medial diameter. The important centrifugal extension of coronary intimal necrotic areas during the fifth decade of life, particularly in male subjects, could not be detected grossly; it required a meticulous light microscopic examination of stained tissue section. This centrifugal extension was sometimes associated with the presence of a "border zone" of intermediate injury developed at the point where the intimal necrotic area irradiated in the direction of blood flow. This distal side of the lesion appeared as a highly irregular boundary with numerous peninsulas of interdigitating necrotic and apparently normal connective tissue. The present results, associated with those of our previous reports, support the view that human atherosclerosis has many attributes of a necrotizing arteriopathy.

Accidents, Traffic↗
PubMed1986

[Centrifugal annular erythema and African trypanosomiasis. Trypanid ].

The skin symptoms of trypanosomiasis in children are reviewed following report of one case of African trypanosomiasis (T. Gambiense). Trypanids, existing in 10-20% of patients during blood and lymphatic dissemination, appear are transient centrifugal annular erythemas made of few elements located on the trunk and roots of arms and thighs. Centrifugal annular erythema in a context of severe infections disease in a exposed subject coming from and endemic zone constitutes a characteristic diagnostic element.

Child, Preschool↗
PubMed1986

Continuous-flow centrifugation hemapheresis in the horse.

In a continuous-flow centrifugation apheresis technique adapted for blood-component separation and collection in horses, hydroxyethyl starch was not required for erythrocyte sedimentation. The efficacy and separation characteristics of whole blood from 10 horses were evaluated at various gravitational forces (700 to 1,500 rpm), using a constant withdrawal rate (100 ml/min). Maximum leukocyte collection occurred at 700 rpm (P less than 0.01), and optimal neutrophil collection occurred at 700 to 750 rpm (P less than 0.01). Although neutrophil counts decreased and lymphocyte counts remained constant at higher rpm settings, an optimal rpm range could not be determined for lymphocyte collection. Peak platelet collection occurred at 1,500 rpm. The response of whole blood from 5 horses was evaluated at lower (500 to 700 rpm) and higher (1,400 to 2,200 rpm) centrifuge speeds. A constant whole blood withdrawal rate of 100 ml/min and a leukocyte collection rate of 3 ml/min were maintained. The optimal rpm settings were determined and compared with values obtained from the 10 horses. Significant differences (P less than 0.01) did not exist between maximum numbers of leukocytes collected at low and high speeds. There was a significant (P less than 0.01) decrease in neutrophils and a concomitant increase in the numbers of lymphocytes recovered at the higher rpm. Platelet yields increased as rpm was increased to 2,000.

Animals↗
PubMed1981

Buffer-induced rat liver mitochondrial aggregation during differential centrifugation.

Use of buffers in homogenization media can result in loss of considerable particulate enzyme activity even with low-speed centrifugation. Addition of tris chloride buffer to 0.25 M sucrose homogenization media resulted in precipitation of 80 to 95% of the activity of two mitochondrial marker enzymes (3-hydroxy-3-methylglutaryl CoA lyase and citrate synthase) with the nuclear fraction during differential centrifugation. Lactate dehydrogenase, a cytoplasmic marker, was not precipitated under the same conditions, indicating that the precipitated enzymes were not associated with intact cells. Photomicrographs showed that tris chloride buffers resulted in mitochondrial aggregation. Isolated mitochondria resuspended in tris chloride or potassium phosphate buffer also aggregated, which resulted in a marked decrease in assayable mitochondrial enzyme activity.

Animals↗
PubMed1980

Cycle-dependent anticancer drug cytotoxicity in mammalian cells synchronized by centrifugal elutriation.

The cycle-dependent cytotoxicity of seven chemotherapy agents was compared with the use of subpopulations of Chinese hamster ovary cells separated into the various phases of the cell cycle by centrifugal elutriation. The proportion of cells killed by either beta-cytosine arabinoside or hydroxyurea agreed well with the proportion of S-phase cells in the treated subpopulations. Cell-cycle survival patterns were also determined for bleomycin (BLM), adriamycin (ADR), cis-diamminedichloroplatinum (II) (cis-DDP), Asaley, and Yoshi 864. Three of the agents (cis-DDP, Asaley, and Yoshi 864) had similar cell-cycle survival patterns in that they all preferentially killed cells in the G1 phase. In contrast, BLM preferentially killed cells in G2+M phase, whereas ADR was most cytotoxic to cells in middle to late S-phase. This investigation demonstrated that separation of cultured mammalian cells into the various cell-cycle phases by centrifugal elutriation allows the rapid determination of the phase-dependent cytotoxic effects exerted by chemotherapy agents.

Animals↗
PubMed1983

[Measurement of radioligand binding to beta-adrenergic and benzodiazepine receptors in the cerebral cortex of the rat. Comparison of filtration and centrifugation technics].

The efficiency of separation of the radioligand receptor complex from the unbound ligand by both rapid filtration and centrifugation is compared for two standard receptor assays in the rat brain: the beta-adrenergic receptor using 3H-dihydroalprenolol and the benzodiazepine receptor using 3H-flunitrazepam. Whereas in beta-adrenergic binding studies both separation procedures yield similar binding data, the apparent binding in the benzodiazepine receptor assay is lower in the filtration experiments as compared to the data obtained by centrifugation, indicating an incomplete retention of the ligand receptor complex by filter. However, in both assays the results of the binding studies are highly dependent on the type of filters used. The following filters were compared: glass fibre filters GE/B and GF/C (Whatman Ltd., Kent, England), membrane filter HAWP (pore size 0.45 micrometer, Millipore Corporation, Bedford, U.S.A.) and glass fibre filters NK I, NK VIII, NK-15-90, NK 13-90, NK 14-120 (all produced by VEB Feinpapierfabrik Neu-Kaliss, G.D.R.). Although a somewhat higher specific binding can be obtained by the membrane filter and several types of the NK filters as compared to the most widely used Whatman GF/C the manifold higher unspecific binding of the radioligand by these filters does not favour their use in ligand assays. Retention as well as unspecific binding of the filter NK VIII is very similar to the Whatman GF/C filter. This new filter seems, therefore, well suited for radioligand studies.

Animals↗
PubMed1983

Centrifugal analyzer used for enzyme immunoassay of progesterone and choriomammotropin.

Recently we developed an enzyme immunoassay involving the use of steroid delta-isomerase (EC 5.3.3.1) as enzyme label and exclusion-affinity chromatography for rapid separation of free antigen-enzyme conjugate that bound to antibodies (J. Immunol. Methods 35: 267-284, 1980). Here we describe an automated version of this procedure, for immunoassay of progesterone and choriomammotropin (human placental lactogen) in serum with the use of a centrifugal analyzer. After incubation, suitable dilutions of sera or extract plus antiserum, conjugate, and double antibody were filtered on an estradiol affinity gel-filtration column; the enzyme activity of the filtrates was determined with the centrifugal analyzer. Results correlate well with those obtained by radioimmunoassay: r (progesterone) = 0.980, r (choriomammotropin) = 0.940. The within-run and between-run precision, specificity, sensitivity, accuracy, and speed of this system make it a useful tool for immunoassay.

Autoanalysis↗
PubMed1976

[Centrifugal fibers in the human retina].

The examination of 16 human retina stained in toto according to the Gallego method (1953) demonstrated the presence of centrifugal optic fibers. These fibers appear as large argyrophilic axons and can be traced as of the papille, amongst the centripetal optic fibers. The centrifugal fibers show a high degree of ramification which may extend over a quarter of the total retinal surface and terminate in the internal plexiform layer. Elsewhere the existence of perivascular and intravascular axon terminals as well as short axon ganglion nerve cells were demonstrated.

Humans↗
PubMed1981

Enzyme immunoassay and enzyme inhibition assay of methotrexate, with use of the centrifugal analyzer.

Methotrexate was determined by the homogeneous enzyme immunoassay (EMIT) with the Multistat and CentrifiChem centrifugal analyzers and by the enzyme inhibition assay with use of the Multistat centrifugal analyzer. With both methods, the standard curve extends from 0.2 to 2.0 mumol/L and there is no interference from bilirubin in concentrations up to 100 mg/L. Moderately lipemic samples do not interfere with the EMIT method, but lower the values obtained with the enzyme inhibition assay. Hemoglobin concentrations as great as 1 g/L do not affect results for methotrexate obtained by the enzyme inhibition assay. With the EMIT assay, methotrexate values are lowered in samples containing hemoglobin in concentrations exceeding 750 mg/L. With the EMIT assay, the following compounds in concentrations of 1 mmol/L do not interfere: leucovorin, 5-methyl-tetrahydrofolate, 5-fluorouracil, and 6-mercaptopurine. When folic acid (100 mumol/L) was added to a serum that did not contain methotrexate, a response equivalent to 0.15 mumol/L was obtained. Methotrexate is stable for five days in serum stored at 23, 4, or -20 degrees C. Within-run precision (CV) for the enzyme inhibition method ranged from 4.7 to 8.1% and for the EMIT assay from 2.5 to 6.2%. Methotrexate concentrations in the serum of children receiving high-dose therapy were compared by three methods: competitive protein binding, EMIT, and enzyme inhibition assays. The correlation coefficients averaged 0.95.

Binding, Competitive↗
PubMed1982

Ultrastructural study on centrifugal fibers in the feline retina.

Morphological studies were carried out to elucidate whether centrifugal fibers are present in the cat retina. Unilateral optic nerve transection with the minimum vascular damage was performed at 6 mm behind the eyeball via the soft palate approach in adult specific pathogen free cats. Light and electron microscopic observations were performed at 40 and 96 hours after the optic nerve transection. At 40 hours, when there was no evidence of degenerative change in the retinal ganglion cells, degenerative changes were observed in the neuronal processes in the outer part of the inner plexiform layer. Two forms of degeneration occurred in close proximity to the cell bodies or the processes of amacrine cells: electron opaque and electron lucent degeneration. Since degeneration of the ganglion cells became manifest at 96 hours, the early neuronal changes in the inner plexiform layer were thought to represent degeneration of the centrifugal fibers.

Animals↗
PubMed1981

Protein-facilitated intermembrane transfer of squalene. Demonstration by density gradient centrifugation.

Squalene-enriched, trypsinized microsomes display no squalene epoxidase activity either as such or when combined with normal microsomes. On addition of microgram quantities of supernatant protein factor to the combined system, squalene epoxidation commences at once and continues at a rapid rate (Friedlander, E. J., Caras, I. W., Lin, L. F., and Bloch, K. (1980) J. Biol. Chem. 255, 8042-8045). When mixtures of trypsin-treated, [3H]squalene-containing microsomes and normal microsomes are subjected to isopycnic density gradient centrifugation, the two microsomal populations separate readily. Essentially all of the radioactive squalene remains associated with the lighter (trypsinized) fraction of microsomes. However, if the mixture of microsomes is initially incubated with supernatant protein factor and then centrifuged, a large fraction of labeled squalene sediments with the denser, normal microsomes. Thus, supernatant protein factor mediates the transfer of squalene from one microsome population to another. This conclusion had previously been reached on the basis of less direct experiments (Friedlander, E. J., Caras, I. W., Lin, L. F., and Bloch, K. (1980) J. Biol. Chem. 255, 8042-8045). Evidence is presented that the process of supernatant protein factor-mediated squalene transfer does not involve membrane fusion and proceeds also in the reverse direction.

Animals↗