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PubMed1979

Flow cytometry analysis of early DNA content changes in human and monkey cells following infection with Simian Virus 40.

Simian virus 40 (SV40) is capable of inducing cellular DNA synthesis in permissive and nonpermissive cells. Utilizing flow cytometry, we analyzed the DNA content changes in two diploid human cell strains and two monkey cell lines. The osteogenesis imperfecta (OI) human skin fibroblasts were induced into DNA synthesis, and within one to two cell generations, a polyploid cell population was produced. With WI-38 phase II cells, a similar pattern of increased cycling of cells into DNA synthesis was observed; however, the majority (approximately 60%) of the cells were blocked in the G2 + M phase of the cell cycle. At later time intervals, an increase in the G1 population was demonstrated. The two monkey cell lines responded to SV40 virus with an accumulation of cells in the G2 + M phase of the cell cycle. Thus, two diploid human cell strains exhibited different cell cycle kinetics early after infection with SV40 virus. The one strain (WI-38) behaved similarly to the two monkey cell lines studied. The other strain (OI) responded similarly to nonpermissive (transforming) cells infected with SV40 virus.

Animals↗
PubMed1979

Slit-scan flow cytometry of mammalian chromosomes.

A flow cytometer has been constructed which measures total fluorescence and the distribution of fluorescence along isolated, stained mammalian chromosomes. In this device, chromosomes flow lengthwise at 4 m/sec through a 1-micrometer thick laser beam. The fluorescence from each chromosome is recorded at 10 nsec intervals; the sequence of recorded values represents the distribution of fluorescence along the chromosome and is stored in the memory of a waveform recorder. The total fluorescence of each chromosome is also measured and recorded. Preliminary studies show that doublets of 1.83 micrometers diameter microspheres flow with their long axes parallel to the direction of flow and that the two microspheres are resolved in the slit-scan profile. Ethidium bromide stained Muntjac and Chinese hamster chromosomes have also been slit-scanned. Centromeres were resolved in many of the Nos. 1 and 2 Chinese hamster chromosomes and the Nos. 1 and X + 3 Muntjac chromosomes.

Animals↗
PubMed1979

Subpopulations of human peripheral blood cells: analysis of granulocytic progenitor cells by flow cytometry and immunologic surface markers.

Normal human peripheral blood cells were separated into different populations based upon isopycnic sedimentation, E rosetting, and EAC rosetting. Each population was characterized according to morphology, surface markers, granulocytic colony formation in semi-solid media, and stainable RNA content by acridine orange (AO) flow cytometry. These techniques enrich for a population of cells that is characterized by a lymphoid morphology, a high granulocytic-macrophage progenitor cell cloning efficiency, a lack of surface markers, and a high stainable RNA content not found in the other two populations of peripheral blood lymphocytes (T cells and B cells). The stainable RNA content serves as a new metabolic marker for the population of cells in which the preponderance of granulocytic progenitor cells reside.

B-Lymphocytes↗
PubMed1978

Lack of evidence of chalone activity in used medium and extract of JB-1 tumor cells in vitro. A flow cytometry study.

In cell-free mouse ascites fluid from the JB-1 ascites tumor in the plateau phase of growth low-molecular chalone substances have been found which reversibly and specifically arrest JB-1 cells in the G1 and G2 phase of the cell cycle. The aim of this study was to investigate whether chalones were involved in the regulation of in vitro growth of JB-1 tumor cells. Used medium and cell extract from confluent, stationary JB-1 cell cultures were investigated for proliferation-inhibitory properties. JB-1 cells from stationary cultures were explanted in test cultures and the traverse of cells through the S phase was investigated by means of flow cytometry (FCM). Inhibition--expressed as a delay of the traverse of cells through the S phase--was not observed when a surplus of used medium, concentrated and fractionated used medium or concentrated and fractionated cell extract from JB-1 cells in vitro was added to test cultures. On the contrary, used medium and concentrated and fractionated used medium stimulated growth. Thus, no involvement of chalones in the growth regulation of JB-1 tumor cells in vitro was detected.

Animals↗
PubMed2026

Papillary Thyroid Carcinoma with Terminal Immune Exhaustion Phenotype Correlates with Increased Risk of Lymph Node Metastasis: An Exploratory Study Combining Flow Cytometry and TCGA.

BACKGROUND: Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy, with lymph node metastasis (LNM) being a key predictor of recurrence and poor prognosis. Preoperative detection of LNM remains challenging due to the limitations of imaging modalities, leading to inadequate surgical resection in 20-30% of patients. While immune checkpoint molecules have been implicated in PTC progression, the heterogeneity of CD8+ T cell exhaustion subsets and their specific association with LNM remain poorly defined. In this study, we aimed to perform an exploratory characterization of the distinct immune landscape of PTC prone to LNM, with a focus on terminal immune exhaustion, in order to generate hypotheses for improved risk stratification and therapeutic strategies. METHODS: Fresh PTC tissues from 40 patients (22 LNM-positive and 18 LNM-negative) were analyzed via flow cytometry (FCM) to quantify immune cell subsets, inflammatory cytokines, and chemokines. Immunohistochemistry (IHC) validated CD45+ immune cell infiltration. Transcriptomic and clinical data from 448 PTC patients in The Cancer Genome Atlas (TCGA-PTC) cohort were used for bioinformatic analysis consistent with the observed phenotype, including Gene Set Variation Analysis (GSVA) of terminal exhaustion gene signatures. RESULTS: LNM-positive PTC exhibited a unique inflammatory milieu with significantly elevated IL-6, IL-1ra, CCL5, and IL-9 levels (all p < 0.05) in tumor interstitial fluid. FCM analysis revealed that LNM-positive PTC had increased infiltration of total CD45+ immune cells, CD3+ T cells, and CD3+CD8+ T cells (all p < 0.05). Critically, terminally exhausted PD-1hiTIM-3+ CD8+ T cells were significantly enriched in LNM-positive PTC (p = 0.022) and positively correlated with extrathyroidal extension (p = 0.044). Additionally, LNM risk was associated with increased CD4+ regulatory T (Treg) cell frequency (p = 0.023) and elevated CTLA-4 expression on CD4+ T cells (p = 0.047). In TCGA-PTC validation, the terminal exhaustion gene signature was predominantly enriched in LNM-positive (p < 0.0001) and advanced-stage PTC (p < 0.001) and strongly correlated with BRAF mutation (predominantly V600E) (p < 0.0001)-the most common oncogenic driver in aggressive PTC. CONCLUSIONS: Our findings suggest a terminal immune exhaustion phenotype (characterized by PD-1hiTIM-3+ CD8+ T cells and Treg enrichment) as a potential key feature associated with LNM-prone PTC. This phenotype shows consistency across clinical samples and TCGA datasets, linking BRAF mutation (predominantly V600E) to immune suppression and metastatic potential. These insights provide a novel exploratory immune-based biomarker for LNM risk stratification and support the potential of combining anti-PD-1/TIM-3 therapy with BRAF inhibitors for high-risk PTC, which should be confirmed in future studies.

lymph node metastasis↗
PubMedDate not supplied

Cytomorphology of gynecologic specimens analyzed and sorted by two-parameter flow cytometry.

The purpose of this study was to define the fluorescence and light scatter properties of the different cell types encountered in gynecologic specimens. Samples stained with Chromomycins A3 were analyzed on a laser-activated electronic cell sorter, and two-parameter histograms of the cell populations were generated from measurements of nuclear fluorescence and small angle light scatter. Cell populations with defined scatter and fluorescence ranges were sorted, stained by a modified Papanicolaou technique, and evaluated using conventional cytomorphologic criteria. We focused on determining which regions of the histogram corresponded with abnormal cells and cells defining specimen adequacy (columnar and metaplastic cells). Sorted cells corresponding with the main fluorescence region are single, benign, mononuclear cells. Relative proportions of the different types of cells in this region vary with light scatter. Leukocytes predominate at low scatter, mature squamous cells predominate at high scatter, and metaplastic and endocervical cells occur throughout this range. Cells sorted with higher values of nuclear fluorescence include dysplastic and malignant cells as well as benign cells occurring as groups, multinucleates, or with adherent leukocytes or bacteria. This study demonstrates that cytomorphology is a useful method for monitoring and interpreting flow cytometry data.

Chromomycin A3↗
PubMed1979

Dual-laser flow cytometry of single mammalian cells.

An improved dual-laser flow cytometric system for quantitative analysis and sorting of mammalian cells has been developed using a low-power argon and high-power krypton laser as illumination sources, thus permitting the excitation of fluorescent dyes having absorption regions ranging from the ultraviolet to infrared. Cells stained in liquid suspension with fluorescent dyes enter a flow chamber where they intersect two spatially separated laser beams. Separate pairs of quartz beam-shaping optics focus each beam onto the cell stream. Electro-optical sensors measure fluorescence and light scatter signals from cells that are processed electronically and displayed as frequency distribution histograms. Cells also can be electronically separated and microscopically identified. The ease and versatility of operation designed into this system represent a marked technological improvement for dual-laser excited flow systems. Details of this instrument are described along with illustrative examples of cells stained with mithramycin and rhodamine and analyzed for DNA content, total protein, and nuclear and cytoplasmic diameter.

Animals↗
PubMed1979

Estimation of membrane potentials of individual lymphocytes by flow cytometry.

The membrane potentials of individual cells can be estimated by flow cytometric quantitation of the cells' uptake of the fluorescent lipophilic cationic dye 3,3'-dihexyloxacarbocyanine iodide. Human lymphocytes separated from peripheral blood on Hypaque-Ficoll gradients are uniformly depolarized by gramicidin and hyperpolarized by valinomycin. Concanavalin A and phytohemagglutinin depolarize only a fraction of the lymphocytes. The flow cytometric technique allows precise detection of heterogeneous membrane potential responses to stimuli such as lectins; it could also provide a basis for sorting cells that respond differently to a given stimulus.

Cations↗
PubMed1979

Spectra of cells in flow cytometry using a vidicon detector.

A TV type vidicon detector was interfaced to a flow cytometer (FCM) to obtain spectra of fluorophores in cells during flow. The normal operations of the FCM are undisturbed. A spectrograph spreads 320 nm of the fluorophore fluorescence emission across the 500 channels of the detector. Spectra of fluorescamine (a surface labeling agent) and of propidium iodide (a nuclear stain) were obtained from Balb 3T3 cells, and the chlorophyll and phycobilin peaks were resolved from flowing blue-green algae in the FCM. Under typical flow conditions, operation of the vidicon in the continuous mode gives for these fluorophores a S/N of several hundred to one in approximately 3 sec. The vidicon was also gated to obtain spectra of single cells and of cells in selected portions of the cell cycle. For example, the spectrum of fluorescamine was obtained from cells in the G1 phase of the growth cycle by using as a gate trigger the FCM discriminator output derived from the propidium iodide signal.

Animals↗
PubMed1979

Flow cytometry of human spermatozoa.

Methods are given for the preparation and staining of human spermatozoa for flow cytometric DNA measurements. Using agents for the reductive cleavage of disulfide crosslinks and suitable proteolytic enzymes an effective decondensation of the sperm chromatin and a DNA-proportional uptake of fluorochromes is achieved. Thus reliable and precise measurements of the relative DNA content of human spermatozoa are possible and the two subpopulations of haploid spermatozoa can be distinguished according to the difference in their DNA content.

DNA↗
PubMed1978

Hydrodynamic orientation of sperm heads for flow cytometry.

Two specially shaped sample injection tubes orient flat-shaped mature sperm heads in a flow cytometer. Orientation allows control of a photometric difficulty experienced with some flow cytometers in the measurement of fluorescent and scattered light from sperm and other flat cells. Both relative DNA-stain content and a measure of cell flatness can now be determined simultaneously for each cell at the high rates possible with flow instruments.

Animals↗
PubMed1977

Measurement of mammalian sperm deoxyribonucleic acid by flow cytometry. Problems and approaches.

Measurement of mammalian sperm deoxyribonucleic acid content is of importance in several areas of biomedical research. When measured in flow systems with orthogonal axes of illumination, flow and detection, an unexpected, distorted distribution consisting of a narrow peak with a lateral extension to the right is observed. Several lines of evidence lead to the conclusion that this effect is an optical-geometric artifact attributable to the flat shape and high index of refraction of mammalian sperm heads. This artifact disappears when an epiillumination flow system is used in which the optic axes for illumination and detection and the flow axis are all coincident. Other approaches also eliminate the artifact. The resulting coefficients of variation observed after acriflavine-Feulgen staining are 4-5%, short of the goal of 1.5% required to distinguish between human sperm bearing X and Y chromosomes and to develop a mutagen test system using mice.

Acriflavine↗
PubMed1979

Flow cytometry of mammalian sperm: progress in DNA and morphology measurement.

Variability in DNA content and head shape of mammalian sperm are potentially useful markers for flow cytometric monitoring of genetic damage in spermatogenic cells. The high refractive index and extreme flatness of the sperm heads produce an optical effect which interferes with DNA measurements in flow cytometers which have dye excitation and fluorescence light collection normal to the axis of flow. Orientation of sperm in flow controls this effect and results in coefficients of variation of 2.5% and 4.2%, respectively, for DNA measurements of mouse and human sperm. Alternatively, the optical effect can be used to generate shape-related information. Measurements on randomly oriented sperm from three mammalian species using a pair of fluorescence detectors indicate that large shape differences are detectable. Acriflavine-Feulgen stained sperm nuclei are significantly bleached during flow cytometric measurements at power levels routinely used in many flow cytometers. Dual beam studies of this phenomenon indicate it may be useful in detecting abnormally shaped sperm.

Animals↗
PubMed1979

The T-lymphocyte as a diploid reference standard for flow cytometry.

T-lymphocytes prepared from the peripheral blood of normal individuals exhibit uniform postmitotic DNA contents that are constant from individual to individual when fixed in ethanol and stained with mithramycin, or when fixed in formalin and stained with acriflavine-Feulgen and analyzed by flow microfluorometry. T-lymphocytes fixed by either method are stable on storage for several months. These cells are suitable for use as an external diploid reference standard for flow cytometric detection of cells with abnormalities in postmitotic content exceeding 5% of diploid reference. Cells with abnormalities in postmitotic DNA content of less than 5% can be detected in mixtures containing both normal and malignant cells by multiparameter analysis.

DNA↗
PubMed1979

Flow cytometry as a new method for the measurement of electrophoretic mobility of erythrocytes using membrane charge staining by fluoresceinated polycations.

The binding of FITC-labeled poly-L-ornithine and poly-L-lysine to fresh or neuraminidase treated human, rat or rabbit erythrocytes was investigated by simultaneous cell volume and cell membrane fluorescence measurements in a flow cytometer. The cell volume was converted into cell surface and the distribution curve of the fluorescence/micrometer2 cell surface was calculated from all histogram classes by a computer program. The mean fluorescence/micrometer2 cell surface as a measure of the density of the negative charges on the cell surface was directly proportional to the elctrophoretic mobility of the erythrocytes, showing that polycation binding can effectively be used for the measurement of the electrophoretic mobility of erythrocytes. The computer fitting of the experimental two parameter histograms by two dimensional Gaussian normal distributions was found to be a very efficient way of data reduction, and a good separation of overlapping cell clusters was possible even in the case of low total numbers of cells in the histogram.

Animals↗
PubMed1979

Different sensitivity of chromatin to acid denaturation in quiescent and cycling cells as revealed by flow cytometry.

The properties of DNA in situ as reflected by its staining with acridine orange are different in quiescent nonstimulated lymphocytes as compared with interphase lymphocytes that have entered the cell cycle after stimulation by mitogens. The difference is seen after cell treatment with buffers at pH 1.5 (1.3-1.9 range) followed by staining with acridine orange at pH 2.6 (2.3-2.9). Under these conditions the red metachromatic fluorescence of the acridine orange-DNA complex is higher in quiescent cells than in the cycling lymphocytes while the orthochromatic green fluorescence is higher in the cycling, interphase cells. The results suggest that DNA in condensed chromatin of quiescent lymphocytes (as in metaphase chromosomes) is more sensitive to acid-denaturation than DNA in dispersed chromatin of the cycling interphase cells. The phenomenon is used for flow cytometric differentiation between G0 and G1 cells and between G2 and M cells. In contrast to normal lymphocytes the method applied to neoplastic cells indicates the presence of cell subpopulations with condensed chromatin but with DNA content characteristic not only of G1 but also of S and G2 cells. The possibility that these cells represent quiescent (resting) subpopulations, arrested in G1, S and/or G2, is discussed.

Cell Cycle↗