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At least 991 records · Page 55Linked to original sources
PubMed2000

Transfusion of washed and centrifuged shed RBCs during maxillofacial surgery affects cytokine concentrations.

BACKGROUND: In patients undergoing elective maxillofacial surgery, hyperthermic reactions have been observed after the transfusion of autologous washed and centrifuged shed blood. It was the aim of this study to correlate the clinical features with changes in cytokine levels. STUDY DESIGN AND METHODS: In 24 consecutive patients, TNFalpha, IL-1, and IL-6 levels were determined in washed and centrifuged shed RBCs (CS RBCs) and in the patient's serum before, as well as 15 and 120 minutes after transfusion. At the same time, blood was drawn for culture. Patients in whom whole blood was saved through the use of acute normovolemic hemodilution served as a control group (n = 6). RESULTS: After the transfusion of CS RBCs, patients had not only elevated cytokine levels but also transient bacteremia involving the pathogens previously detected in CS RBCs. No rise in body temperature occurred. CONCLUSION: In the light of these results, the use of CS RBCs in patients undergoing maxillofacial surgery should be restricted to those patients with no primary bacterial contamination.

Adolescent↗
PubMed2001

A novel microplate agglutination method for blood grouping and reverse typing without the need for centrifugation.

BACKGROUND: Current agglutination tests and solid-phase adherence methods, employed as the techniques for RBC typing and antibody screening, require centrifugation and washing steps. This report describes a novel agglutination method for forward and reverse grouping that is based on the formation of an RBC monolayer on a microplate without the need for centrifugation and washing. STUDY DESIGN AND METHODS: In a comparative study, 2225 samples from healthy regular blood donors were tested for ABO, Rh (D, C, c, E, and e), K, and reverse grouping, in parallel, by the new microplate agglutination method and a commercially available blood testing system, which served as a reference method. RESULTS: In the case of forward grouping, 0.37 percent of samples tested were false negative in the new method and 1.35 percent tested false negative in the reference blood testing system. In addition, the reverse grouping reference method showed 0.4 percent false-positive and 2.6 percent false-negative results. In contrast, the new method gave false-positive results in only 0.09 percent and false-negative results in 0.67 percent of the cases tested. CONCLUSION: These results, as well as the possibility of adapting this method to a fully automated system, suggest that our novel agglutination method could be an important contribution to the field of immunohematology.

Blood Grouping and Crossmatching↗
PubMed2003

Residual cell content in plasma produced by three centrifugal apheresis procedures.

BACKGROUND: Understanding the impact of collection procedures on the residual amount of blood cells in plasma for transfusion and for fractionation is of current interest. This prospective work evaluated plasma donations collected on an apheresis machine (PCS 2, Haemonetics) with three different automatic centrifugal apheresis procedures, currently largely used in the US (Revision G) and in Europe (Revision F), and included a new procedure that uses a high-separation core (HSC) that is designed with a second separation chamber to further separate cells from plasma. STUDY DESIGN AND METHODS: A total of 90 collection procedures have been performed from a population of 37 donors, under comprehensively standardized conditions. There were 30 well-matched donors in each group. Plasma aliquots were taken from the plasma units within 30 minutes of the end of the collection procedures and immediately assessed for WBCs, RBCs, PLTs, and supernatant Hb. RESULTS: In Revision F and Revision G plasma donations, the mean numbers of WBCs were 83.1 x 10(4) and 311 x 10(4) per L; PLTs, 5.01 x 10(9) and 20 x 10(9) per L; and RBCs, 58 x 10(6) and 43 x 10(6) per L, respectively [corrected]. Significantly lower values were found with the HSC procedure (mean WBC, RBC, and PLT counts, 3.01 x 10(4)/L [p < 0.05], 9 x 10(6)/L [p < 0.001], and 3.5 x 10(9)/L [p < 0.001], respectively). The amount of free Hb was similar in all three procedures. CONCLUSION: Significant differences in numbers of cells in plasma were found depending on the centrifugal procedures used and the design of the separation bowl. The lowest level of cell contamination was found with the new HSC bowl, which without a filtration step, yielded plasma that met the standard for WBC-reduced plasma. Plasma collectors can select the most appropriate method of plasma collection based on donor criteria, use of plasma (transfusion, viral inactivation, or fractionation), and local or international regulations, when in place.

Blood Cell Count↗
PubMed2003

Autosynchronized systolic unloading during left ventricular assist with a centrifugal pump.

OBJECTIVES: The purpose of this study was to investigate how the inflow cannulation site of the left ventricular assist system with a centrifugal pump would influence cardiac function on failing heart models. METHODS: In 10 sheep, a left ventricular assist system was instituted by an outflow cannula in the descending aorta, two inflow cannulas in the left atrium and the left ventricle, and connecting those cannulas to a magnetically suspended centrifugal pump. A conductance catheter and a tipped micromanometer for monitoring the pressure-volume loop were also inserted into the left ventricle. Myocardial oxygen consumption was directly measured. Heart failure was induced by injection of microspheres into the left main coronary artery. The assist rate was varied from 0% to 100% at each inflow cannulation site. RESULTS: The pump flow with left ventricular cannulation increased during the systolic phase and decreased during the diastolic phase, whereas it was constant with left atrial cannulation. Ejection fraction with left atrial cannulation decreased as the assist rate increased, whereas that with left ventricular cannulation was maintained up to 75% assist. The external work with left atrial cannulation decreased gradually as the assist rate increased, whereas the external work with left ventricular cannulation did not decrease until the assist rate reached 75%. The myocardial oxygen consumption in both cannulations decreased proportionally as the assist rate increased; they were significantly less with left ventricular cannulation at the 100% assist rate than with left atrial cannulation. CONCLUSION: Left ventricular cannulation during left ventricular assistance maintains ejection fraction and effectively reduces oxygen consumption.

Analysis of Variance↗
PubMed1980

A rapid method of isolation and fractionation of proteoglycans using a vertical tube rotor for isopycnic centrifugation.

A comparison was made between a vertical tube rotor and a fixed angle rotor for isopycnic centrifugation of proteoglycans. In the vertical tube rotor, isopycnic gradient was achieved much faster than in the conventional fixed angle rotor. The use of a vertical tube rotor for isopycnic centrifugation shortens the time considerably for the isolation of proteoglycans from various tissues.

Animals↗
PubMed1982

An automatic method for Thrombotest on the 'Cobas Bio' centrifugal analyser.

The Thrombotest assay has been adapted to the 'Cobas Bio' centrifugal analyser and an excellent correlation (r = 0.9972) to results obtained on a coagulometer was found. When the centrifugal analyser is linked to a computer, this method will reduce the manual labour and time by approximately 50% when larger series are concerned.

Autoanalysis↗
PubMed2003

Novel method for continuous cell separation by density gradient centrifugation: evaluation of a miniature separation column.

A compact bench-top model of the centrifuge enables continuous cell separation based on density differences. The apparatus holds a small separation disk equipped with a circular channel (8 mL capacity) separated by a septum. A set of isotonic Percoll media with different densities is continuously introduced at one terminal and collected from the other. Under a centrifugal force field, cell suspension introduced into the proximal portion of the channel results in continuous separation of cells according to their densities. The performance of the apparatus was demonstrated with the separation of human buffy coat containing nucleated cells (>10(8)) among a large population (10(10)) of RBC. The results indicated that the method is capable of separating a large number of nucleated cells, with minimum damage, for a few hours of operation wherein neutrophils are well resolved from lymphocytes. The method may be applied to other types of samples including cord blood, blood from small animals, cultured cells, pancreatic beta cell islets, malaria parasites, sperm cells, etc.

Blood Cell Count↗
PubMed2004

Preparative separation of proteins using centrifugal precipitation chromatography based on solubility in ammonium sulfate solution.

A preparative modification of the centrifugal precipitation chromatography (CPC) is described. The sample-loading capacity is improved in the present system by the use of convoluted tubing containing dialysis tubing instead of a dialysis membrane placed between a pair of disks equipped with mirror-imaged spiral grooves as in the original design. The system uses, basically, the same principle of as the original CPC, in that a concentration gradient of precipitant is generated under a centrifugal force field. The protein sample injected into the CPC column is exposed to an increasing concentration of the precipitant where it precipitates at various portions of the column according to its solubility. The gradient is then gradually lowered so that the sample undergoes dissolution and precipitation many times within the column; the proteins finally elute from the column according to their solubilities. A basic study was performed using this machine to separate human albumin and 3-globulin using ammonium sulfate (AS) as precipitant. Preliminary results indicate that this method can separate 500 mg of protein.

Ammonium Sulfate↗
PubMed1974

Isopycnic centrifugation of chromatin in renografin solutions.

Solutions of Renografin (30-60%) can be centrifuged to form density gradients in the range from 1.0 g/cm(3) to 1.4 g/cm(3) or, alternatively, preformed gradients can be made which under appropriate conditions of centrifugation have an indefinite stability. Such solutions have a low viscosity and a relatively low ionic strength. The density of DNA in such solutions is surprisingly low ( approximately 1.14 g/cm(3)). Crude chromatin can be sedimented to an equilibrium position in such gradients, corresponding to a density of 1.2(4) g/cm(3), or slightly lower, depending on the method of preparation. The complex is shown to contain DNA, RNA, protein, and possibly some lipoprotein. Most of the RNA can be removed with RNase without any significant effect on the density of the chromatin.

Amino Acids↗
PubMed1961

Electron microscopy of centrifuged hyphae of Neurospora.

Normal and centrifuged hyphae of Neurospora were studied with the electron microscope. The following cell structures could be identified: nuclei with nucleoli, mitochondria, endoplasmic reticulum, ribosomes, glycogen, fat bodies, vacuoles, and vesicles with an inner canalicular system, of unknown nature. In centrifuged hyphae, the glycogen layer appeared as a light area, with a slight indication of granular structure. The ribosome layer consisted of densely packed ribosomes without any membranes. The mitochondrial layer contained spaces filled with ribosomes. The nuclei were loosely packed, with endoplasmic reticulum between them. The "enchylema" layer was composed of vesicles belonging to the endoplasmic reticulum. The vacuolar layer was poorly preserved and consisted of double-walled vesicles. Fat appeared as stellate osmiophilic droplets. These observations were compared with previous observations under the optical microscope and their meaning for cell physiology was discussed.

Animals↗
PubMed1950

Chemical studies in host-virus interactions; immunochemical studies on the purity of concentrates of various bacterial viruses prepared by differential centrifugation procedures with an appendix summarizing data on the desoxyribonucleic acid content of these viruses.

Three mutant pairs of bacterial viruses T2r(+) and T2r, T4r(+) and T4r, T6r(+) and T6r, have been concentrated by differential centrifugation and analyzed. Under conditions of prolonged lysis of organisms grown on broth-agar, the virus concentrates frequently contained phosphorus (P) other than that contained in desoxyribose nucleic acid (DNA). These concentrates reacted with antisera to the host organism, E. coli, specifically precipitating the non-DNA-P but not virus activity or DNA. The amounts of nitrogen precipitated in the virus concentrates by antisera were related to their content of non-DNA-P. These viruses could be purified by differential centrifugation after such treatment to yield preparations apparently free of P other than DNA-P. It has been concluded that there is no satisfactory evidence for the presence of ribose nucleic acid as a constituent part of these viruses.

Appendix↗
PubMed1988

Enrichment and selection of hybrid hybridomas by Percoll density gradient centrifugation and fluorescent-activated cell sorting.

Hybrid hybridomas, producing bi-specific monoclonal antibodies that react with horseradish peroxidase and human IgA1 were isolated by sorting the double-fluorescent cells on single-cell basis after fusion of two hybridomas, previously labelled green or red by octadecylamine-FITC or -TRITC, respectively. The double-fluorescent fused cells were significantly different in AXL (size) and RAS (internal structure) distribution compared with the (non-fused) mono-fluorescent cells. The percentage of double-fluorescent cells and the viability of these cells could be increased by Percoll density gradient centrifugation. As a result, there was an 8-fold increase of total isolated hybrid hybridomas (up to 30% of all tested clones) compared to isolations without Percoll density gradient centrifugation. All the isolated hybrid hybridoma clones had similar amounts of DNA, equal to the sum of the DNA of both parental hybridomas.

Antibodies, Monoclonal↗
PubMed1995

Adaptation of a functional assay for protein S to a Cobas Fara II centrifugal analyzer.

An adaptation of the manual Staclot protein S functional assay (American Bioproducts, Parsippany, NJ) for the Cobas FARA II centrifugal analyzer is described. This automated method is based on determining the clotting time by measuring the change in turbidity of the specimen as clotting progresses. The accurate and precise pipetting of the analyzer combined with its enhanced data acquisition and rapid parallel processing features result in a markedly improved procedure compared to the less accurate and reproducible manual method. The assay is linear over the range of protein S concentrations encountered clinically (0% to 150%); has a limit of detection of 3% protein S; within and between day precision (CV) at a level of 50% protein S is 4.7 and 12.6%, respectively; and results agree closely with those obtained on the STA automated hemostasis analyzer (slope = 0.98, intercept 3.92, and r = 0.98). Protein S values obtained with this assay for specimens from 20 normal males and 20 normal females were 115% +/- 22.31% (mean +/- standard deviation [SD]) and 98% +/- 18.2%, respectively. In 14 patients on chronic stable treatment with Coumadin (DuPont Pharmaceuticals, Wilmington, DE) the mean functional protein S activity was 16.2% and the SD 11.7%. The method for determination of protein S activity on the centrifugal analyzer yields results comparable to data reported with a variety of other techniques.

Anticoagulants↗
PubMed1989

Successful use of shell vial centrifugation and 16 to 18-hour immunofluorescent staining for the detection of influenza A and B in clinical specimens.

The rapid diagnosis of influenza A and B infections is beneficial for the proper management of patients with acute respiratory illness. The authors evaluated a shell vial centrifugation method to detect these viruses 16-18 hours postinoculation and compared it with conventional tube cell culture. Rhesus monkey kidney cells were used in both methods. Conventional culture of 334 respiratory specimens recovered 64 influenza isolates; the average time to positivity was 4.1 days. Low-speed shell vial centrifugation with polyclonal immunofluorescent staining 16-18 hours postinoculation was performed on 96 fresh specimens and on an additional 38 frozen specimens. These 134 specimens contained 49 of the 64 total influenza-positive specimens. The shell vial method yielded a sensitivity of 90.9% and 87.5% for fresh and frozen specimens, respectively, as compared with conventional tube cell culture. The authors conclude that the shell vial method is an important adjunct to conventional culture for the rapid detection of influenza A and B in clinical specimens.

Bronchoalveolar Lavage Fluid↗
PubMed1997

Percoll gradient centrifugation can be omitted in sperm preparation for intracytoplasmic sperm injection.

Prior to intracytoplasmic sperm injection (ICSI), seminal fluid is currently washed out from the ejaculated semen and further sperm selection is carried out by a discontinuous Percoll gradient. Possible deleterious effects from the sperm-separating substance Percoll on sperm function or embryo cleavage after in-vitro fertilization (IVF) have, to our knowledge, not yet been reported and the use of Percoll has been widely accepted in IVF. In this study, we examined whether the omission of the Percoll step in the sperm preparation has any influence on the outcome of the ICSI procedure. Two methods of sperm preparation for ICSI were compared in a controlled study on sibling oocytes: washing the semen sample once, followed by a Percoll gradient centrifugation versus washing the sperm sample twice without a Percoll gradient centrifugation. The mean fertilization rates were similar for the two sperm preparation methods: 78.2 +/- 21.4 and 75.0 +/- 24.1% respectively of the intact oocytes displaying two pronuclei. Cleavage rates did not differ statistically between the two groups. Whereas in both groups similar percentages of excellent, good and poor quality embryos were obtained, the percentage of fair quality embryos was significantly higher in the group without Percoll (16.3 +/- 20.1 versus 9.1 +/- 15.7%). However, no statistical differences were observed in either the percentage of transferable embryos or in the percentage of embryos actually transferred or frozen in the two groups. In conclusion, spermatozoa from ejaculates that are washed out from the seminal fluid without any further selection can be used for ICSI without any adverse effect on fertilization and embryo cleavage.

Cell Separation↗
PubMed2000

Bacterial contamination and sperm recovery after semen preparation by density gradient centrifugation using silane-coated silica particles at different g forces.

The effects of density gradient centrifugation through silane-coated silica particles (PureSperm) using 100, 200, 300 and 500 g on bacterial contamination of sperm samples and recovery of motile spermatozoa from sperm samples were investigated with conventional culturing techniques and microscopic visual assessment. The recovery of motile spermatozoa was variable and was not improved using 500 g compared to the recommended 300 g. The bacterial contamination was highly decreased by gradient centrifugation through PureSperm and was almost abolished when strict aseptic techniques were used, with changes to sterile Pasteur pipettes and tubes prior to washing procedures.

Adult↗
PubMed2001

Interrelationships between seminal parameters and sperm nuclear DNA damage before and after density gradient centrifugation: implications for assisted conception.

BACKGROUND: With an increase in the use of assisted reproduction technologies the requirements of the diagnostic semen analysis are constantly changing. METHODS: Spermatozoa from patients undergoing IVF were analysed by examining the conventional semen parameters and DNA/chromatin integrity, using in-situ nick translation (NT) and the Chromomycin A(3) fluorochrome, which indirectly demonstrates a decreased presence of protamine. Samples were examined before and after preparation using discontinuous density gradient centrifugation. RESULTS: Density gradient centrifugation enriched samples by improving the percentage of morphologically normal forms by 138% and sperm nuclear integrity by 450%. Sperm nuclear integrity as assessed by in-situ nick translation (NT) demonstrated a very clear relationship with sperm concentration, motility and morphology. Morphology correlated with fertilization rates of patients undergoing IVF, while NT values of the spermatozoa post-preparation were significantly lower in pregnant patients. CONCLUSIONS: We have demonstrated that along with the classical semen parameters, the assessment of nuclear integrity improves the characterization of the semen sample and may be used as a tool for allocating patients to specific assisted reproduction treatments.

Adult↗
PubMed1975

Analysis by isopycnic centrifugation of isolated nucleoids of Escherichia coli.

The isolated, formaldehyde-fixed nucleoid of E. coli has been analyzed by isopycnic centrifugation in CsCl density gradients. The membrane-free nucleoid bands at a density of 1.69 +/- 0.02 g/cm3. The membrane-associated nucleoid bands at a density of 1.46 +/- 0.02 g/cm3. Both species sediment to equilibrium as nearly monodisperse bands in CsCl, suggesting that the nucleoid components of DNA, RNA and protein are present in relatively constant ratios. These ratios are constant regardless of the position of the nucleoids in the heterogeneous sedimentation profile of a preparative sucrose gradient. The fixed nucleoids remain condensed during isopycnic centrifugation and there is no detectable loss of RNA from the nucleoid.

Bacterial Proteins↗