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PubMed2002

Leukocyte apheresis using a centrifugal cell separator in refractory ulcerative colitis: a multicenter open label trial.

Recently, successful results of ulcerative colitis (UC) treatments with leukocyte apheresis have been reported by several institutes. To certify the efficacy of leukocyte apheresis in refractory UC patients, a multicenter open label trial was conducted, and results were analyzed. Fifty patients diagnosed with active steroid-resistant UC were enrolled in this study from 14 medical centers. Using a centrifugal cell separator (Component Collection System, Haemonetics), leukocyte apheresis was performed once a week for 5 weeks. General conditions and abdominal symptoms were recorded daily, and laboratory tests were followed weekly. Changes of colonoscopic and histological manifestations of luminal activity through the study period were evaluated. At the end of the study period, stool frequency was decreased to less than 4 times a day in 68.4% (26 of 38) and serum C-reactive protein (CRP) concentration was normalized in 56.7% (17 of 30) of the patients. Colonoscopic remission was achieved in 57.7% (26 of 45), and histological improvement was noted in 54.1% (20 of 37) of the patients tested. Improved disease activity was demonstrated in 74% (37 of 50) of the patients by general assessment criteria. Analysis of the trial data confirmed the valid clinical efficacy of leukocyte apheresis by centrifugal cell separator in refractory UC patients.

Adult↗
PubMed2006

Postoperative support with the centrifugal pump ventricular assist device (VAD).

Centrifugal pump left ventricular assist device is a useful adjunct in pediatric cardiac surgery, as a bridge to recovery, or in some cases, to transplantation. This form of circulatory support may not have the universal applicability of extracorporeal membrane oxygenation, but it is equally or more effective in properly selected patients. The technology for centrifugal pump support is now quite standardized, and the advantages well documented. In this chapter we discuss the problems of indications, case selection, technical aspects of the circuit, and general clinical management. Results since 1989 are also presented.

Algorithms↗
PubMed2002

Centripetal and centrifugal reorganizations of frequency map of auditory cortex in gerbils.

As repetitive acoustic stimulation and auditory conditioning do, electric stimulation of the primary auditory cortex (AI) evokes reorganization of the frequency map of AI, as well as of the subcortical auditory nuclei. The reorganization is caused by shifts in best frequencies (BFs) of neurons either toward (centripetal) or away from (centrifugal) the BF of stimulated cortical neurons. In AI of the Mongolian gerbil, we found that focal electrical stimulation evoked a centripetal BF shift in an elliptical area centered at the stimulated neurons and a centrifugal BF shift in a zone surrounding it. The 1.9-mm long major and 1.1-mm long minor axes of the elliptical area were parallel and orthogonal to the frequency axis, respectively. The width of the surrounding zone was 0.2-0.3 mm. Such "center-surround" reorganization has not yet been found in any sensory cortex except AI of the gerbil. The ellipse is similar to the arborization pattern of pyramidal neurons, the major source of excitatory horizontal connections in AI, whereas the surrounding zone is compatible to the arborization range of small basket cells (inhibitory neurons) in AI.

Animals↗
PubMed1984

Bead centrifuge tube inserts--a semi-quantitative theory.

A semi-quantitative theory is proposed for the sedimentation of particles in centrifuge tubes filled with polymer beads acting as sedimentation aids. The theory concerns the attainment of approximate sedimentation-diffusion equilibrium in minimum time of centrifugation. It is shown empirically that the time to reach this state is approximately proportional to the diameter of the polymer beads as predicted by the theory.

Diffusion↗
PubMed1960

Electron microscopy of the centrifuged sea urchin egg, with a note on the structure of the ground cytoplasm.

Centrifuged, unfertilized eggs of the sea urchin, Arbacia punctulata, have been studied with the electron microscope. Subcellular particles were stratified by centrifuging living cells, known to be normally fertilizable, for five minutes at 3,000 g. The layered subcellular particles, including cortical granules, 16 mmicro RNP particles, pigment, yolk, mitochondria, and oil droplets, possess characteristic ultrastructural features by which they may be identified in situ. The clear zone contains 16 mmicro particles, most of them freely dispersed, scattered mitochondria, and a few composite structures made up of annulate lamellae in parallel layers or in association with dense, spherical aggregates of the RNP particles. Free 16 mmicro particles are found, in addition, throughout the cell, in the interstices between the stratified larger particles. They show a tendency to form ramifying aggregates resulting from certain types of injury to the cell. A few vesicular structures, found mainly in the clear zone, have attached RNP particles, and appear to be related to the ER of tissue cells. Other vesicles, bounded by smooth membranes, are found throughout the cell. These are extremely variable in size, number, and distribution; their total number appears to depend upon conditions of fixation. It is suggested that limited formation of such structures is a normal property of the ground cytoplasm in this cell, but that fixed cells with very large numbers of smooth surfaced vesicles have produced the latter as a response to chemical injury. A model of the ground cytoplasm is proposed whose aim is to reconcile the rheological behavior of the living cell with the ultrastructural features observed.

Animals↗
PubMed1953

Studies on entry and egress of poliomyelitic infection. VI. Centrifugal spread of the virus into peripheral nerve with notes on its possible implications.

We have demonstrated a progressive centrifugal migration of poliomyelitis virus from the CNS into various peripheral ganglia and into peripheral nerves, including their distal portions. This phenomenon appears to be a regular occurrence in experimental animals, and is similar to that found in two other neurotropic infections, rabies and Borna disease. Viremia appears to be secondary to primary neural infection. The presence of virus in the lumen of the alimentary tract appears to be secondary to primary neural infection and not to viremia, and to be associated with the centrifugal spread of virus in peripheral nerves. The presence of virus in "extraneural" tissues is not per se referable to infection of their constituent cells but rather to infection of their supplying nerves or, in some instances, to their content of virus-bearing blood. The finding of virus in the vagus nerve may throw light on some of the electrocardiographic changes noted in certain cases of human poliomyelitis. The presence of virus in peripheral nerves may throw light on the etiology of the most frequent clinical manifestations of human poliomyelitis, localized pain and tenderness.

Animals↗
PubMed2001

High-efficiency gene transfer into rhesus macaque primary T lymphocytes by combining 32 degrees C centrifugation and CH-296-coated plates: effect of gene transfer protocol on T cell homing receptor expression.

Although steady progress has been made in transducing human T lymphocytes by Moloney murine leukemia virus (Mo-MuLV)-based vectors, few studies have been done to define ex vivo gene transfer protocols to transduce rhesus macaque primary T lymphocytes. Given the fact that simian immunodeficiency virus (SIV) infection in rhesus macaque is a well-characterized model for human immunodeficiency virus (HIV), it is of great interest to develop an efficient protocol to transduce rhesus macaque primary T cells. In this study, we have used MuLV-10A1-pseudotyped retrovirus expressing enhanced green fluorescent protein (EGFP) to evaluate a number of ex vivo gene transfer protocols in rhesus macaque primary T lymphocytes. Our objectives in designing these protocols were (1) to test whether higher efficiency gene transfer could be obtained by combining two previously defined protocols, centrifugation at 32 degrees C and the CH-296-coated plate; and (2) to study the effect of an ex vivo gene transfer protocol on the expression of lymphocyte homing receptors L-selectin and alpha 4 beta 7 and alpha 4 beta 1 integrins. From seven independent experiments we demonstrate by flow cytometry analyses of EGFP expression that whereas centrifugation at 32 degrees C or the fibronectin fragment CH-296-coated plate protocol alone yielded 10-14% transduction efficiency, combining these two protocols resulted in 28.1-51.2% transduction efficiency. EGFP in transduced cells was expressed highly throughout the 14 days of posttransduction expansion. Our results also demonstrate that whereas the transduction procedure per se did not significantly alter the expression of lymphocyte homing receptors, anti-CD3 and anti-CD28 antibody stimulation profoundly reduced the expression of L-selectin. The selective reduction of L-selectin may result in significant in vivo consequences if transduced cells are infused.

Animals↗
PubMed1980

Rapid centrifugal analyzer enzyme immunoassays for phenytoin, phenobarbital, and primidone.

The adaptation of the homogeneous enzyme immunoassays (EMIT) for phenytoin, phenobarbital, and primidone to a centrifugal analyzer is described. The sample volume required was 10 microliter, and the assay had the capacity to analyze sera from 28 patients within 180 sec. The assay temperature was 30 C, and absorbance was monitored at 340 nm. Coefficients of variation for within-day precision ranged from 2.1% to 3.7%, and analytic recovery was quantitative. The centrifugal analyzer EMIT assay results correlated well with those obtained using high-pressure liquid and gas-liquid chromatographic technics. A logit-log transformation of the absorbance rate versus concentration data was obtained using a modified Gauss-Newtonian nonlinear least-squares fit analysis. Severe hemolysis and lipemia caused interference.

Computers↗
PubMed2005

Rapid and selective surveillance of Arabidopsis thaliana genome annotations with Centrifuge.

UNLABELLED: Centrifuge is a user-friendly system to simultaneously access Arabidopsis gene annotations and intra- and inter-organism sequence comparison data. The tool allows rapid retrieval of user-selected data for each annotated Arabidopsis gene providing, in any combination, data on the following features: predicted protein properties such as mass, pI, cellular location and transmembrane domains; SWISS-PROT annotations; Interpro domains; Gene Ontology records; verified transcription; BLAST matches to the proteomes of A.thaliana, Oryza sativa (rice), Caenorhabditis elegans, Drosophila melanogaster and Homo sapiens. The tool lends itself particularly well to the rapid analysis of contigs or of tens or hundreds of genes identified by high-throughput gene expression experiments. In these cases, a summary table of principal predicted protein features for all genes is given followed by more detailed reports for each individual gene. Centrifuge can also be used for single gene analysis or in a word search mode. AVAILABILITY: http://centrifuge.unil.ch/ CONTACT: edward.farmer@unil.ch.

Arabidopsis↗
PubMed1999

Differential centrifugal afferents to the anterior and posterior accessory olfactory bulb.

The centrifugal afferents to the anterior and posterior divisions of the accessory olfactory bulb (AOB) were investigated after iontophoretic injections of dextranamines. Injections affecting the anterior and posterior or just the posterior division of the AOB gave rise to retrogradely labeled cells in the bed nuclei of the accessory olfactory tract and stria terminalis and in the anterodorsal medial and posteromedial cortical (PMCo) amygdaloid nuclei. Injections restricted to the anterior division of the AOB yielded similar results, although no cells were observed in the PMCo. These results demonstrate differential centrifugal inputs to the anterior and posterior divisions of the AOB, probably to the granular layer, and provide further support for the hypothesis of a functionally segregated vomeronasal system.

Afferent Pathways↗
PubMedDate not supplied

Pulsatile operation of a centrifugal ventricular assist device with magnetic bearings.

A prototype bench top model of a continuous flow ventricular assist device using an impeller suspended by magnetic bearings has been developed. Generation of a pulsatile pressure was studied using both a computer model and in vitro loop tests of the prototype. The motivation for developing a computer model for a blood pump in the natural circulation is two-fold. First, it allows simulation of the pump under a large variety of operating conditions. Second, it provides insight into what parameters of the system design are important for achieving a specific result. For example, in one case, an aortic pressure of 118/87 mmHg was generated by varying the speed from 2,000 to 2,600 rpm. The computer model was verified by coupling the centrifugal pump prototype to a mock circulatory system. The results of the model were verified by generating an aortic pressure of 113/78 mmHg while varying the speed from 2,000 to 2,600 rpm. These experiments have shown that it is possible to generate pulsatile pressure similar to that of native physiology using a centrifugal left ventricular assist device. Further tests will be required to quantify the effects on hemolysis.

Biomedical Engineering↗
PubMed1989

Sarns centrifugal pump for repair of thoracic aortic injury: case reports.

A new centrifugal pump (Sarns), originally designed for ventricular assist, was successfully used in two patients during repair of traumatic pseudoaneurysm of the descending thoracic aorta. The distal thoracic aorta was perfused without heparinization to avoid spinal cord and visceral ischemia, reduce afterload on the heart, and avoid clamp injury to the aorta. Distal mean aortic pressure was maintained above 50 mm Hg with a mean pump flow of 1.75 liter/minute. Proposed structural advantages of the Sarns centrifugal pump for perfusion of the distal thoracic aorta without heparin are resistance to thrombus formation, air embolus, and hemolysis.

Accidents, Traffic↗
PubMed1979

Isolation by differential and zonal centrifugation of minicells segregated by Escherichia coli.

Minicells segregated from Escherichia coli chi925 carrying a drug-resistance plasmid were separated from nucleated cells by differential centrifugation and purified by rate-zonal centrifugation in sucrose gradients. Minicells purified in this way were capable of donating the plasmid to nucleated cells. They also incorporated thymidine, uridine and methionine into macromolecules. Methods are described for purification of plasmid-containing minicells on a scale large enough to allow isolation of DNA, DNA polymerase and RNA polymerase in sufficient quantities for studies of enzymes involved in replication and transcription of plasmid DNA.

Cell Fractionation↗
PubMed1982

Isolation of spinach leaf peroxisomes in 0.25 molar sucrose solution by percoll density gradient centrifugation.

A procedure for isolating spinach (Spinacia oleracea L.) leaf peroxisomes in 0.25 molar sucrose solution by Percoll density gradient centrifugation followed by removal of the Percoll by washing and centrifugation was established. The preparation contains more than 90% peroxisomes as intact organelles with no detectable chlorophyll or cytochrome oxidase contamination. The peroxisomes are stable at 0 to 4 degrees C or 25 degrees C for at least 2 hours.

Journal Article↗
PubMed1984

Purification of peroxisomes and mitochondria from spinach leaf by percoll gradient centrifugation.

A procedure was developed to purify simultaneously peroxisomes and mitochondria from spinach (Spinacia oleracea L.) leaf under isoosmotic and low viscosity conditions. This method involved differential centrifugation and density gradient centrifugation on four layers of Percoll. Chlorophyll-free preparations of highly intact and active organelles were obtained and cross-contamination was negligible. Both organelles were stable for several hours, even if they remained in Percoll. Purified mitochondria were able to carry out the oxidation of different substrates with excellent respiratory control and ADP:O ratios. The method described in the present work was also suitable to purify mitochondria and peroxisomes from potato (Solanum tuberosum L.) tubers.

Journal Article↗
PubMed1989

Quantification of urinary growth hormone (GH) excretion by centrifugal ultrafiltration and radioimmunoassay: appraisal of the relationship between 24 h urinary GH and mean 24 h serum GH levels in normal and abnormal states of GH secretion.

We have applied a simple method for the quantification of 24 h urinary GH excretion (24 h UGH), combining centrifugal ultrafiltration and radio-immunoassay (RIA), to an appraisal of the relationship between 24 h UGH and mean 24 h serum GH levels in normal and abnormal states of GH secretion. Forty-four subjects, comprising 13 normal adults, 12 short-statured subjects and 19 subjects with active acromegaly, underwent blood sampling at 20-min intervals and concurrent urine collection for 24 h. Mean 24 h serum GH and 24 h UGH were also determined in four post-menopausal women before and during cyclical oestrogen replacement therapy, and 24 h UGH was measured in six normal men prior to and following the subcutaneous administration of biosynthetic GH (0.2 IU/kg). Each subject's mean 24 h serum GH level was determined by assaying a 'pooled' sample, derived from equal aliquots of the 73 serum samples obtained during the 24 h study. The method for quantification of 24 h UGH employs centrifugal microconcentrators, and involves a 50-fold concentration of urine, followed by dialysis and RIA. Surface adsorptive hormone loss during sample collection and ultrafiltration is minimized by the prior addition of bovine serum albumin to the urine collection container. Immunoreactive GH in ultrafiltered urine dilutes in parallel with the RIA standard curve. GH is stable in urine stored at - 20 degrees C for at least 12 months. There was a highly significant correlation between 24 h UGH and mean 24 h serum GH values obtained from the combined population of normal adults (including the post-menopausal women during oestrogen therapy) and short-statured subjects (r = 0.69, P less than 0.0001). A significant correlation was also found in short-statured subjects alone (r = 0.63, P less than 0.05). In contrast, there was no significant correlation between 24 h UGH and mean 24 h serum GH in subjects with active acromegaly, and their 24 h UGH values were not distinguishable from those of the 'non-acromegalic' subjects. A significant increase in 24 h UGH occurred in the post-menopausal women given cyclical oestrogen replacement therapy (9.7 +/- 2.6 (mean +/- SE) to 24.6 +/- 1.0 muIU/mmol creatinine, P less than 0.02), reflecting the increase in their mean 24 h serum GH levels (0.8 +/- 0.3 to 5.3 +/- 0.7 mIU/l, P less than 0.01). Twenty-four hour UGH increased from 4.6 +/- 0.6 to 17.1 +/- 2.1 muIU/mmol creatinine (P less than 0.002) in the men given biosynthetic GH. Twenty-four hour UGH measurements reflect mean 24 h serum GH levels in normal adults and short-statured subjects. While the measurement of 24 h UGH shows promise as an investigative tool, our results cast doubt on its use in the diagnosis of acromegaly.

Acromegaly↗
PubMed1975

The effect of a single or double dose of dexamethasone on granulocyte collection with the continuous flow centrifuge.

A total of 33 leukaphereses were performed with the IBM continuous flow centrifuge on 28 normal healthy donors for the purpose of obtaining increased yields of granulocytes for infusion into leukopenic recipients. The pretreatment of donors within a 10- to 12-hour period prior to pheresis with a double dose of dexamethasone and the addition of hydroxyethyl starch to the input line of the continuous flow centrifuge, significantly increased the total quantity and efficiency of granulocyte collected as compared to a donor group receiving a single dose of dexamethasone in addition to hydroxyethyl starch. A mean of 25.5 times 10-9 total granulocytes were collected in addition to an efficiency of 2.11 times 10-9 granulocytes harvested per liter of blood processed in the double-dose-treated donors, in contrast to 19.6 times 10-9 total granulocytes collected and an efficiency of 1.82 times 10-9 granulocytes harvested per liter of blood processed in the single dose donor group. The results of the present study demonstrate that elevated quantities of granulocytes can be collected from normal donors by scheduling a double dose of dexamethasone prior to the pheresis procedure.

Blood Specimen Collection↗
PubMed1982

A simple method for the standardization of centrifugation procedures in blood component preparation.

The total sedimentation effect in centrifugation procedures is described by including the phases of acceleration and retardation and expressing the effect by the product g X s. 91 CPD whole blood units were centrifuged at different speeds and times, between 373 g for 9 min 52 s and 2,606 g for 22 s. All procedures gave a sedimentation effect of 244,090 g X s. The platelet yield in the platelet-rich plasma was 78-92% of whole blood. No significant difference was observed between low g force for a long time as compared to high g force for a short time.

Blood Transfusion↗