PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Flow Cytometry”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 1,423 records · Page 79Linked to original sources
PubMed1995

Comparison between image and flow cytometry. A priori factors that influence technique.

Comparisons between flow cytometry (FCM) and image cytometry (ICM) have found a high concordance rate in pancreatic tissue, with some discrepancies between the two procedures. This study utilized 40 cases of chronic pancreatitis, primary pancreatic adenocarcinoma and metastatic pancreatic adenocarcinoma to determine the concordance rate between the two procedures. The reasons for discrepancies were identified and subsequently used to establish methods for a priori determination of which procedure to use. Using the FACSCAN flow cytometer and the CAS 200 on appropriately stained specimens that were disaggregated from 50-micron sections, we achieved a concordance rate of r = .878 (P < .01) after removing outliers. Thirty-one of 40 cases matched DNA content, and 9 cases had discrepant results. These discrepant cases were evaluated with factor analysis, in part because initial observations suggested that the variables evaluated could be combined into unifying concepts. The nine measured variables were compressed into three factors, which accounted for 68% of the variation observed between the two methods. Readily evaluated features, on a case-by-case basis, including tumor/nontumor ratios, accounted for the largest proportion of this variation. These findings suggest that tumor/nontumor cell ratios in hematoxylin-eosin-stained sections may provide adequate a priori information to direct the choice of either FCM or ICM to measure DNA ploidy in pancreatic tissue.

Adenocarcinoma↗
PubMed2000

Flow cytometry of bacteria: glimpses from the past with a view to the future.

Measurement of bacteria and other microorganisms at the level of single cells has progressed enormously over the last couple of decades. Up to the late 1970s, there were no other means than microscopy for observation of single microorganisms, making any type of measurement very cumbersome and tedious, at best. Today, we measure several parameters simultaneously with a precision of a few per cent, and at a rate of 1000 cells per second. The first papers on the use of flow cytometry to measure bacteria appeared only in 1977, although the method had proved highly successful in studies of mammalian cells for almost a decade. There were several reasons for this relatively late introduction, including technical limitations, problems with adequate staining, and, not least, the human factor. Today, flow cytometry has a wide range of microbiological applications, ranging from studies of the bacterial cell cycle and many other cellular characteristics to assessment of antibiotic susceptibility of clinical samples, and monitoring of bacteria and other microorganisms in anything from sewage to sea water. Still, the potential of flow cytometry in microbiology is far from fully utilised. Better instruments and new stains will provide new opportunities to understand, control and exploit this vital part of the biosphere.

Bacteria↗
PubMed1997

Heterogeneity of cell-associated CP5 expression on Staphylococcus aureus strains demonstrated by flow cytometry.

It was reported previously that two capsular polysaccharides, types 5 and 8 (CP5 and CP8), account for 70 to 80% of Staphylococcus aureus strains isolated from human and animal sources. The capsular material has been shown to play a part in virulence and in resistance to phagocytosis. With a view to investigating the role that CP plays in pathogenicity or protection, relative measurement of cell-associated CP is desirable. Flow cytometry, which permits the analysis of individual bacteria, was used to that end. Thirty isolates expressing CP5, of human (n = 7) and animal (cow, n = 11; goat, n = 3; swine, n = 3; hen, n = 3; and rabbit, n = 3) origin, were cultivated on either brain heart infusion agar (BHI) or modified medium 110 (mod 110) agar. Staphylococci were incubated with a mouse anti-CP5 monoclonal antibody (an immunoglobulin M, which does not react with staphylococcal protein A) and then stained with a fluorescein-labeled anti-murine antibody. The bacteria were washed, sonicated, and analyzed by flow cytometry. Except for three isolates, the expression of cell-bound CP5 was higher when bacteria were cultivated on mod 110 than when they were cultivated on BHI. We found a wide intraisolate phenotypic heterogeneity in surface-exposed CP5 in many strains, which appeared as mixtures of stained and unstained bacteria. Four main patterns could be distinguished on the basis of the distribution of the fluorescence of individual bacteria within the strain population as a function of growth medium. Great variations in both percentages of stained bacteria and fluorescence intensity were recorded among strains regardless of their origin. Flow cytometry analysis provided information on both the relative amounts and the distribution patterns of the surface expression of CP. This information is potentially useful for the evaluation of the part played by the capsule in the interaction of bacteria with host cells or for the study of the activities of antibodies to this target antigen, such as opsonization or prevention of adherence.

Animals↗
PubMed1987

Enumeration of terminal deoxynucleotidyl transferase positive cells in leukemia/lymphoma by flow cytometry.

The method to fix single cells in suspension and its application for the detection of TdT-positive cells by flow cytometry are described. In comparison to formalin-methanol fixation, formalin-acetone fixation resulted more formation of aggregated cells which caused non-specific staining. In our assay system 80% cells in human thymus were TdT-positive. Levels of TdT in normal human peripheral blood was 0.5 +/- 0.6% (means +/- 1 S.D., n = 50). A total of 104 patients with leukemia/lymphoma was examined for TdT. TdT-positive cells were detected in ALL (87.5% cases), AML (57.1% cases), CML-BC (58.3% cases) and ML (17.6% cases). Mean channel of fluorescence intensity of the TdT-staining in AML was significantly reduced in comparison with that in ALL. When antigen density of TdT was very low, fluorescence microscopy gave false negative results and flow cytometry could detect this dim fluorescence.

DNA Nucleotidylexotransferase↗
PubMed2006

Screening for platelet antibodies in adult idiopathic thrombocytopenic purpura: a comparative study using solid phase red cell adherence assay and flow cytometry.

BACKGROUND: Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disorder caused by antiplatelet autoantibodies. In this study, we compared 2 methods for screening serum platelet antibodies in patients with ITP. METHODS: A total of 44 adult patients were clinically classified with ITP. We used 2 indirect tests to detect human leukocyte antigen antibodies and/or platelet-specific antibodies in their sera. In method I, we used solid phase red cell adherence (SPRCA) assay. In method II, by flow cytometry, platelets from plateletpheresis components were used as target cells, and fluorescein isothiocyanate-conjugated sheep anti-human IgG Fc was used as the staining reagent. Positive results were defined as any test with the percentage of fluorescence exceeding the reference range by 3% or more in method II. Direct tests detecting platelet-associated IgG on platelets of patients with ITP were done by flow cytometry. RESULTS: Serum specimens from 44 adult patients with ITP (28 female, 16 male) were tested. SPRCA assay could only detect platelet antibodies in 22 patients (50%). By method II, 31 serum specimens (70.5%) yielded positive results. There was a difference between the results of the SPRCA test and method II, with a high degree of significance (p < 0.001) by the McNemar test. No significant difference in platelet counts was observed for patients with and without discernible platelet antibodies by SPRCA assay (p = 0.90). The direct test was positive in 12 patients (66.7%) out of 18 ITP patients tested. CONCLUSION: Flow cytometry is more sensitive than SPRCA assay for detecting platelet antibodies. Detection of platelet antibodies is useful in explaining the immune mechanism and platelet transfusion refractoriness in ITP.

Adolescent↗
PubMed1987

Application of flow cytometry to immunohematology.

A method is described for applying flow cytometry to the analysis of populations of red blood cells that have been sensitized, in vivo or in vitro, with IgG antibody. Specific instrument settings and details of the method are given with sufficient explanation for practical use in immunohematologic investigations.

Antigen-Antibody Reactions↗
PubMed1994

Deoxyribonucleic acid flow cytometry of testicular Leydig cell tumors.

We analyzed by flow cytometry the deoxyribonucleic acid content of 13 paraffin embedded, formalin-fixed Leydig cell tumors of the testis. Of the tumors 10 were clinically benign (9 diploid and 1 aneuploid) and 3 were malignant (aneuploid). The benign aneuploid tumor showed moderate cellular atypia and a low mitotic count (less than 2 per 10 high power fields). Our study suggests that the majority of Leydig cell tumors are diploid and the less common malignant tumors are typically aneuploid, and that deoxyribonucleic acid flow cytometric findings can be useful as a prognostic indicator in these tumors.

Adult↗
PubMed2000

Binding kinetics of soluble ligands to transmembrane proteins: comparing an optical biosensor and dynamic flow cytometry.

BACKGROUND: The kinetics of protein-protein interactions can be monitored with optical biosensors based on the principles of either surface plasmon resonance or mirror resonance. These methods are straightforward for soluble proteins, but not for proteins inserted in the plasma membrane. METHODS: We monitored with an IASys biosensor system, based on a resonant mirror: (1) the binding of cells to an immobilized ligand, (2) the binding of a soluble ligand to immobilized cells, and (3) the binding of a soluble ligand to immobilized plasma membrane vesicles. For comparison, the kinetics of fluorescent antibody binding to intact cells were measured by dynamic flow cytometry. RESULTS: With an optical biosensor, the useful configuration is the one based on immobilized plasma membrane vesicles. However, signals can be detected only for very abundant binding sites (>10(6) per cell). Dynamic flow cytometry allows the accurate determination of the k(on) and k(off) of antibody binding. The sensitivity of the method is two orders of magnitude better than with an optical biosensor. CONCLUSIONS: Although biosensors constitute a method of choice for measuring the interactions between soluble proteins, they are not well suited for measuring the interaction between soluble proteins and membrane-embedded proteins. On the contrary, flow cytometry is well suited for such an application, when it is used in a dynamic mode.

ADP-ribosyl Cyclase↗
PubMed1987

Barrett's esophagus. Correlation between flow cytometry and histology in detection of patients at risk for adenocarcinoma.

The value of endoscopic surveillance biopsy for dysplasia and carcinoma in patients with Barrett's esophagus is controversial. One reason is that the available histologic criteria are not adequate to separate patients with lesser degrees of dysplasia or predysplastic changes who are at increased risk for carcinoma and therefore require more frequent surveillance from those patients who are not at increased risk. We used flow cytometry and histology to evaluate 317 biopsy specimens from 64 consecutive patients who were in a cancer surveillance program for Barrett's esophagus and 3 additional patients with adenocarcinoma in Barrett's esophagus. Specimens from 10 patients had aneuploid cells; 9 of these had dysplasia or carcinoma, or both, but 1 patient had only specialized metaplastic epithelium. Twenty specimens ahd G2/tetraploid fractions greater than 6%; all 20 came from patients who had cancer or dysplasia, or were indefinite for dysplasia. All patients with dysplasia or adenocarcinoma had evidence of genomic instability (aneuploidy) or abnormalities of mucosal proliferation by flow cytometry, even when the dysplasia was focal or difficult to recognize histologically. In a small subset of patients with specialized metaplastic epithelium whose specimens were histologically negative or indefinite for dysplasia, the mucosa had aneuploid cell populations or proliferative abnormalities that were otherwise found only in dysplasia or carcinoma. Additional study may prove that this subset of patients merits more frequent endoscopic biopsy surveillance because of an increased risk for developing carcinoma. Because the abnormalities we have detected by flow cytometry correlate well with the conventional histologic diagnoses of dysplasia and carcinoma, they may prove to be a valuable objective adjunct in the diagnosis of dysplasia and carcinoma in Barrett's esophagus.

Adenocarcinoma↗
PubMed1989

Advances in the diagnosis and management of bladder cancer: flow cytometry, intravesical bacillus Calmette-Guerin, and systemic chemotherapy.

Recent advances in the diagnosis and treatment of patients with bladder cancer include flow cytometry, intravesical bacillus Calmette-Guerin (BCG), and systemic chemotherapy. Once the subjects of clinical research protocols, these modalities are currently being incorporated into the general management of patients with bladder cancer. Flow cytometry, intravesical BCG, and systemic chemotherapy will be individually reviewed and their role in the management of patients with bladder cancer will be discussed.

Antineoplastic Agents↗
PubMed1988

A predictive assay for human tumor cellular response to hyperthermia using dansyl lysine staining and flow cytometry.

The heat response of five human tumor biopsies has been examined using the fluorescent probe dansyl lysine and multiparameter flow cytometry. Dansyl lysine has previously been shown to possess specificity for heat killed mammalian cells. The human tumors tested included a cervical squamous cell carcinoma, malignant melanoma, colon adenocarcinoma, ovarian carcinoma, and a mesothelioma. The samples were excised, mechanically disrupted into single cell suspensions and heated in vitro for various lengths of time at 45 degrees C. The cells were returned to 37 degrees C incubation for 12 to 15 hours prior to staining with dansyl lysine. The fraction of cells staining dansyl lysine was quantitated by flow cytometry after gating on high forward angle light scatter and 90 degrees C light scatter. This gate excluded much of the normal cell contamination within the tumor sample. The data show that the heat response of human tumor biopsies varied significantly, with cervical carcinoma and malignant melanoma being the most resistant and the mesothelioma and ovarian carcinoma the most heat sensitive. Finally, evidence is presented for the expression of thermotolerance in ovarian carcinoma and mesothelioma biopsies pre-heated in vitro. Dansyl lysine appears to be useful in measuring the intrinsic cellular heat sensitivity of human tumors and in determining the kinetics of decay of thermotolerance following an initial heat exposure.

Biopsy↗
PubMed1993

Apoptosis of S-phase HL-60 cells induced by DNA topoisomerase inhibitors: detection of DNA strand breaks by flow cytometry using the in situ nick translation assay.

DNA topoisomerase I inhibitor camptothecin (CAM), topoisomerase II inhibitors teniposide (TN) and amsacrine (m-AMSA) induce apoptosis of HL-60 cells. One of the early events of apoptosis is DNA degradation, which occurs as a result of activation of the specific endonuclease. DNA strand breaks generated during this process were revealed, in the present study, by the in situ nick translation assay which was adapted to flow cytometry. In this assay, the incorporation of biotinylated dUTP by apoptotic cells was detected by the use of fluorescinated avidin, whereas simultaneous staining of DNA with propidium iodide made it possible to correlate the appearance of DNA strand breaks with cell position in the cell cycle. The breaks were detected as early as 90 min after the initial cell contact with CAM, and they were limited to cells in the S phase of the cell cycle. At that early stage of apoptosis DNA was not yet extractable from the cells; the loss of DNA from S-phase cells could not be seen, by flow cytometry, during the initial 2 h of incubation with CAM. DNA strand breaks induced by TN and m-AMSA also occurred preferentially in S-phase cells. The data indicate that DNA strand breaks resulting from activation of endonuclease in HL-60 cells treated with DNA topoisomerase I or II inhibitors can be conveniently measured using the in situ nick translation assay. This assay has certain advantages over other methods of identification of apoptotic cells by flow cytometry, such as providing direct evidence of DNA damage and offering the opportunity to correlate DNA damage with cell position in the cell cycle. The method may be of interest in clinical oncology where testing tumor response (by DNA degradation) to DNA topoisomerase inhibitors or other treatments may be of prognostic value.

Amsacrine↗
PubMed1998

The emergence of flow cytometry for sensitive, real-time measurements of molecular interactions.

The analysis of macromolecular interactions is an essential element of biomedical research. Flow cytometry is uniquely capable of making sensitive and quantitative measurements of molecular interactions. These measurements can be made in real time with subsecond kinetic resolution using purified biomolecules or living cells. Combined with automated sample handling, these features make flow cytometry a versatile and robust technology for the analysis of molecular interactions.

Antigens, Surface↗
PubMed1999

Post-thaw evaluation of dog spermatozoa using new triple fluorescent staining and flow cytometry.

A new triple fluorescent staining method was developed to evaluate frozen-thawed dog spermatozoa. This method was used to compare functional parameters of canine spermatozoa cryopreserved using 2 different freezing-thawing protocols. One ejaculate from each of 10 dogs was split into 2 aliquots and processed using the Andersen method or the CLONE method. Semen samples were evaluated immediately after thawing and after 3 h of incubation at 37 degrees C. Plasma membrane integrity and acrosomal status of the spermatozoa were evaluated simultaneously by flow cytometry using a combination of 3 fluorescent dyes: Carboxy-SNARF-1 (SNARF), to identify the live spermatozoa; propidium iodide (PI), which only stains dead cells or cells with damaged membranes; and fluorescein isothiocyanate (FITC)-conjugated Pisum sativum agglutinin (PSA), which binds to the acrosomal content of spermatozoa with damaged plasma and outer acrosomal membranes. The accuracy of this new staining method in quantifying the proportions of live and dead spermatozoa by flow cytometry was evaluated by comparing it with the staining technique using carboxyfluorescein diacetate and propidium iodide (CFDA-PI), which yielded high correlation coefficients. The triple-stained sperm samples were also analyzed by epifluorescence microscopy, and both methods proved to be highly correlated. Post-thaw progressive motility and plasma membrane integrity were similar for the 2 freezing procedures, but the proportion of damaged acrosomes after thawing was lower using the Andersen method and the spermatozoa had a higher thermoresistance. This new triple staining method for assessing canine sperm viability and acrosomal integrity provides an efficient procedure for evaluating frozen-thawed dog semen samples either by flow cytometry or fluorescence microscopy.

Acrosome↗
PubMed1991

Cell cycle analysis in flow cytometry: use of BrdU labelling and side scatter for the detection of the different cell cycle phases.

Cell cycle analysis in flow cytometry is based on the incorporation of labelled precursors in DNA. The use of BrdU versus SSC, in which side scatter substitutes PI fluorescence, has proved to be useful also for the distinction between G2 and Mitotic cells. Mitoses often produce an SSC decrease due to the morphological changes that happen in the nucleus during this phase of cell cycle. Moreover, DNA accessibility to PI varies during mitosis, as well. However, most of these variations, detectable by flow cytometry appear to be basically dependent on the cell line used.

Bromodeoxyuridine↗
PubMed1990

Flow cytometry of normal and abnormal pig karyotypes. Preliminary report.

Flow cytometry technique was applied to normal pig chromosomes and to three different reciprocal translocations: trcp (4q-; 14p), trcp (3p+;7q-) and trcp (1q-;15q+). The rearranged chromosomes generate new peaks which seem to correspond to their relative lengths. Therefore, it is necessary to confirm these results by banding analysis and/or by hybridization on these chromosomes with probes of genes known to be localized on them.

Animals↗
PubMed1992

Cell proliferation: analysis by flow cytometry.

Cell proliferation can be efficiently analyzed by multiparameter flow cytometry. Different strategies may be used: As a primary approach, static analysis reveals the momentary distribution in a single sample between cell cycle phases, metabolic states, or differentiation lineages. Kinetic analysis uses sequential measurements of cell cycle traverse in synchronized cell populations or accumulation of cells blocked in a particular cell cycle phase. DNA replication analysis is based on the incorporation of the thymidine analogue bromodeoxyuridine. Cell production by mitosis as well as cell loss by cell death can be estimated. Cell production may be assessed by measurement of mitotic rate or S-phase influx. Cycling/non-cycling status may be indicated by proliferation associated antigens. Specific cell clones in experimentally mixed populations can be discriminated using reporter genes. Flow cytometric multiparameter analysis has the potential of revealing and quantitating the heterogeneity with respect to stemlines, proliferation and differentiation. This is of increasing importance in the study of human cancers, as a possible basis for therapeutic decision making.

Antigens↗