bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variance within homogeneous phytoplankton populations, II: Analysis of clonal cultures
Authors: Campbell J. W. , Yentsch C. M. 
Published: August 2005

AbstractIn part I of this series of articles, a framework was presented for interpreting histograms of volume or fluorescence as measured by a flow cytometer on homogeneous phytoplankton populations. In this paper, the analytical framework is applied to flow cytometric histograms from laboratory experiments involving clonal phytoplankton cultures. The density function derived in part I was modified to include a third parameter representing a linear shift of the origin. This modified density function was fitted to chlorophyll fluorescence histograms for populations believed to be asynchronous (grown in continuous light) and also to histograms from populations grown on a 14:10 (h:h) light/dark cycle. Near‐synchronous subpopulations sorted from an asynchronous population were also analyzed. In populations in which underlying assumptions (asynchronous divisions, constant growth) are valid, curve fits provide estimates of the inherent variability among cells at age 0. The implication of fitting the density function to populations in which these assumptions are not valid is discussed.
Variance within homogeneous phytoplankton populations, III: Analysis of natural populations
Authors: Campbell J. W. , Yentsch C. M. , Cucci T. L. 
Published: August 2005

AbstractA theoretical framework for interpreting flow cytometric histograms from homogeneous phytoplankton populations was developed in part I of this series of articles and applied to chlorophyll fluorescence histograms from clonal cultures in part II. In this paper, we demonstrate the application of this framework to the analysis of cell volume distributions found in a natural assemblage of phytoplankton from the Gulf of California. Flow cytometric analyses of a surface water sample incubated for a period of 61 h revealed the sequential growth and decline of three distinct subpopulations. Cell volume distributions for each subpopulation measured at different times were analyzed, and the theoretical density function described in parts I and II was fitted to these distributions. The range of cell volumes within each subpopulation was similar to that predicted for asynchronous populations.
Rapid analytical technique for the assessment of cell metabolic activity in marine microalgae
Authors: Dorsey Judy , Yentsch Clarice M. , Mayo Sara , McKenna Colleen 
Published: August 2005

AbstractA standard method for the assessment of cell viability has been developed for marine phytoplankton using an inexpensive stain, fluorescein diacetate (FDA), at. 75 μM for 10 min. A flow cytometer was used as the fluorescence detector, providing an assessment of viability for each individual particle. Cell size and chlorophyll fluorescence per cell were assessed simultaneously, permitting an assignment of viability to specific subpopulations, thus increasing the power of the technique. A reasonable correspondence between FDA mean fluorescence intensity per cell and an independent metabolic indicator, photosynthetic capacity measured by 14C, was found. Both FDA mean fluorescence intensity and photosynthetic capacity vary as a function of cell volume. Recovery after extended periods of darkness indicate that cells that are FDA negative may not be dead, but merely quiescent or inactive.
A simple method to preserve oceanic phytoplankton for flow cytometric analyses
Authors: Vaulot D. , Courties C. , Partensky F. 
Published: August 2005

AbstractA simple method was developed to preserve marine phytoplankton populations so that delayed flow cytometric analyses could be performed. The method consisted of immediate fixation with 1% glutaraldehyde (final concentration) followed by storage in liquid nitrogen. The method was tested on individual algal species and on natural samples from both coastal and pelagic waters. In most cases, it caused little cell loss and preserved well both forward angle light scatter and chlorophyll fluorescence, but phycoerythrin fluorescence sometimes was significantly increased. The technique performed best for the small‐sized picoplankton (below 2 μm) such as Syne‐chococcus cyanobacteria or the newly discovered oceanic prochlorophytes. For larger‐sized cells it had to be applied on a case by case basis as some fragile species, particularly dinoflagellates and cryptophytes, were poorly preserved.
A flow cytometric approach to assessing the environmental and physiological status of phytoplankton
Authors: Demers Serge , Davis Kimberly , Cucci Terry L. 
Published: August 2005

AbstractIndividual particle analysis using a flow cytometer (FCM) was made on natural phytoplankton communities in oligotrophic waters. Our objective was to develop an assay to yield information on the nutrient history of individual cells using FCM. Results from nutrient assays showed that both biovolume and total red fluorescence are affected by the nutrient conditions in the incubator. The light effect was measured by changes in the chlorophyll content of the cells, and after the 12 h incubation the cells seemed well adapted to the light conditions. The estimated kinetic constant for the chlorophyll synthesis averaged 1.5 × 1.0−2 h−1, whereas the growth rate calculated from the changes in the cell numbers changed from 0.14 to > 2.5 doubling per day. The smallest size fraction presented the highest growth rate ( > 2.5 doublings per day). The relationship between the total red fluorescence as estimated with the FCM and the biovolume revealed that the cells from the 2 m samples at the beginning of the experiment were probably nutrient limited. Important changes in the size of the cells under nutrient limitation were also observed. The FCM data suggest that the FCM is a valuable tool for estimating the relative growth response and nutritional state of natural phytoplankton populations.
Origin and biology of cancer metastasis
Authors: Fidler Isaiah J. 
Published: August 2005

AbstractMetastasis, the spread of cells from a primary neoplasm to distant sites where they grow, contributes to the death of most cancer patients. The process of metastasis is not random. Rather, the process consists of a series of linked, sequential steps that must be completed by tumor cells if a metastasis is to develop. Thus, metastatic cells must succeed in invasion and embolization, survive in the circulation, arrest in a distant capillary bed, and extravasate into and multiply in organ parenchyma. Although some of the steps in this process contain stochastic elements, as a whole metastasis favors the survival and growth of a few subpopulations of cells that preexist within the parent neoplasm. Moreover, metastases can have a clonal origin, and different metastases can originate from the proliferation of single cells. The outcome of metastasis depends on the interaction of metastatic cells with different organ environments. Organ‐specific metastases have been demonstrated in a variety of experimental tumor systems, and even within one organ, site‐specific tumor growth can be found.The conclusion that metastasis is a highly selective process that is influenced by both the intrinsic properties of tumor cells and by host factors is optimistic. A selective process is regulated and therefore can be studied and then manipulated.
Flow cytometry chamber with 4π light collection suitable for epifluorescence microscopes
Authors: Watson James V. 
Published: August 2005

AbstractA compact, solid, spherico‐ellipsoidal chamber (SEC), which has approaching 4π (“all around”) light collection, has been developed for flow cytometry. This was mounted onto the stage of a standard fluorescence photomicroscope, and the camera was replaced by a photomultiplier. Both components can be added or removed in minutes. The increased light collection efficiency of the SEC (about 85%) compared with about 4% from standard chambers enabled a fluorescence microscope with a 50 W mercury vapour lamp to “double” as a flow cytometer. The system was tested with microbeads and cells stained for DNA with ethidium bromide, and results were comparable to those obtained with our laser‐based instrument.
Measurement variability in DNA flow cytometry of replicate samples
Authors: Wheeless Leon L. , Coon John S. , Cox Christopher , Deitch Arline D. , Devere White Ralph W. , Koss Leopold G. , Melamed Myron R. , O'Connell Mary J. , Reeder Jay E. , Weinstein Ronald S. , Wersto Robert P. 
Published: August 2005

AbstractA Bladder Cancer Flow Cytometry Network study has been carried out aimed at identification of the sources of inter‐ and intralaboratory variability. Replicate “cocktail” samples containing a mixture of peripheral blood lymphocytes and an aneuploid cell line and samples of peripheral blood lymphocytes serving as a DNA reference standard were distributed to five network laboratories. The samples were stained for DNA using propidium iodide, with each laboratory using its own staining protocol. Sets of these samples were analyzed by flow cytometry to obtain cellular DNA distributions. DNA index and hyperdiploid fraction were calculated for each histogram using an automated technique. Results were evaluated by analysis of variance to identify sources of variability. Three important sources of variation were found that affect flow cytometry in general and‐the transportability of flow cytometry results to routine clinical use in particular. The significant variation among laboratories that is constant across time most probably represents stable differences in instrumentation, instrument set‐up, and laboratory techniques. This variation can be compensated for, if it is known and stable, to develop transportable classification criteria. The second type of variation, termed the interaction component, represents differences among laboratories that are not constant across time. Sources of this variation include inconsistency in sample preparation, staining, and analysis. The elimination of this type of variation is required for meaningful comparison of data within and among laboratories and the creation of interlaboratory databases. The third type of variation represents pure measurement variability and affects the sensitivity of the technique.
Flow cytometric analysis of protein thiol groups in relation to the cell cycle and the intracellular content of glutathione in rat hepatocytes
Authors: Principe P. , Wilson G. D. , Riley P. A. , Slater T. F. 
Published: August 2005

AbstractThe relationship between protein thiols (PSH) and cell proliferation was examined in ethanol‐fixed rat hepatocytes. A new protocol was developed for simultaneous measurement of protein thiol vs. DNA content by flow cytometry. The fluorescent dye o‐phthalaldehyde (OPT) was used for flow cytometric measurements of protein thiol groups. The influence of nonprotein thiols was examined by monitoring the cell cycle of cells in which the glutathione content (GSH) was modified by treatment with buthionine sulphoximine (BSO). Three rat liver cell lines (IAR 20, IAR 6.1, IAR 6.1RT7) were used: these cell lines possess different growth characteristics and degrees of tumorigenicity, which made it possible toanalyse changes in PSH during normal and deranged cell proliferation. The effects on the cell cycle of the changes in PSH due to the depletion of GSH were measured by 5‐bromo‐2'‐deoxyuridine (BrdUrd) incorporation and flow cytometry. The data obtained can be summarised as follows: (a) OPT fluorescence increases with increasing DNA content in all rat liver cell lines examined; (b) the greatest variation in PSH content occurs in G1. There is a smaller variation in G2 + M, and PSH levels are relatively invariant throughout S‐phase; (c) a higher content of PSH is found in the tumorigenic cell lines; (d) the amount and distribution of PSH is not affected by BSO treatment; (e) kinetic studies indicate that BSO treatment has no effect on the ability of the IAR rat liver cell lines to progress through the cycle.
Dual‐parameter flow cytometric analysis of an early lymphocyte activation antigen (CK226) and DNA content
Authors: Zocchi M. Raffaella , Heltai Silvia , Poggi Alessandro 
Published: August 2005

AbstractThis study provides a direct correlation, via dual‐parameter flow cytometric analysis (simultaneous assessement of surface immunofluorescence and DNA content), between activated T‐cell entry into the S/G2/M phases of the cell cycle and the kinetics of expression of a novel T‐cell activation antigen, termed CK226. This molecule was identified by the specific monoclonal antibody on the leukaemic T‐cell line CEM/K, and it was expressed by 8–30% of resting peripheral blood lymphocytes and the majority of monocytes and granulocytes. A large fraction of activated lymphocytes acquired the CK226 antigen before DNA synthesis. Moreover, this molecule was expressed on virtually all G0/G1 and S/G2/M phase cells by day 2 after phytohaemoagglutinin (PHA) activation and at day 6 after stimulation in a mixed lymphocyte culture. The time course of expression of other known activation antigens, such as Tac and transferrin receptor, was comparable to that of CK226. Based on the relationships between CK226 expression on cycling cells and the stimulatory effects of the specific monoclonal antibody, we conclude that CK226 should be considered an early activation antigen, which defines a new pathway of T‐cell activation.
Separation of hepatocytes of different acinar zones by flow cytometry
Authors: Thalhammer T. , Gessl A. , Braakman I. , Graf J. 
Published: August 2005

AbstractHepatocytes in the proximal (zone 1) and distal (zone 3) regions of the liver acinus are selectively stained by perfusion of the isolated rat liver with 0.2–20 μM acridine orange (AO). After 10–60 min of anterograde perfusion, AO fluorescence is visible in zone 1 cells, whereas retrograde perfusion stains cells of zone 3. In this paper, we describe a technique to isolate a mixed population of fluorescent and nonfluorescent hepatocytes (cells from all acinar zones, which do not loose the zone specific AO labeling) and to separate these cells according to their zonal origin by fluorescence activated cell sorting. The zonal populations obtained were either fluorescent or non‐fluorescent (purity >95%). Separated cell fractions differed in their enzyme content (5' nucleotidase, succinate‐dehydrogenase, β‐glucuronidase). An unidentified AO metabolite, which is not found in bile after retrograde perfusion (not formed in zone 3 cells), is also absent after retrograde perfusion in sorted fluorescent cells (zone 3 cells), indicating zonal purity of sorted cells.
Flow cytometric analysis of the kinetic effects of cisplatin on lung cancer cells
Authors: Fujikane Toshiaki , Shimizu Tetsuo , Tsuji Tadakatsu , Ishida Sakae , Ohsaki Yoshinobu , Onodera Sokichi 
Published: August 2005

AbstractThe effects of cisplatin on the cell cycle and DNA synthesis of human lung adenocarcinoma cell line PC‐9 were examined by flow cytometry. The cellular DNA content and the bromodeoxyuridine (BrdUrd) incorporation rate were measured simultaneously using a monoclonal anti‐BrdUrd antibody. Following exposure to cisplatin (1.0 μg/ml) for 1 and 24 hr, the bivariate DNA/BrdUrd distributions revealed a delayed S‐phase transit and an accumulation of cells in the G2M phase. The BrdUrd‐linked green fluorescence intensity continued to decrease with the lapse of time. However, early‐and mid‐S‐phase cells soon recovered DNA synthesis activity, and the former showed higher activity than the control cells. These findings suggested the vigorous DNA synthesis of cells in early S phase. However, for quantitative analysis of chemotherapeutic effects, some problems remained to be resolved regarding the condition for DNA denaturation and its alteration by the agents.
Cytokinetic analysis of lung cancer by bromodeoxyuridine labeling of cytology specimens
Authors: Ten Velde G. P. M. , Schutte B. , Reijnders M. M. J. , Bosman F. T. , Blijham G. H. 
Published: August 2005

AbstractRecent flow cytometric (FCM) studies have indicated the prognostic value of S‐phase cells (SPF) in lung cancer. More refined cytokinetic analysis can be obtained by dual‐parameter FCM, labeling S‐phase cells with 5‐bromodeoxyuridine (BrdUrd), which can be detected using a monoclonal antibody (MoAb) to BrdUrd. Tumor cells obtained through bronchoscopic brush were incubated for 1 hr in RPMI 1640 medium with 10% fetal calf serum and 10 m̈M BrdUrd. After fixation in ethanol, pepsin treatment, and DNA denaturation, the nuclei were stained with anti‐BrdUrd MoAb and propidium iodide. From 14 of 20 patients, sufficient material was obtained (three adenocarcinoma and seven squamous cell, one giant cell, and three small cell carcinoma). The measured SPF ranged from 5.2% to 26%. The labeling index (LI), calculated as the ratio of the number of BrdUrd‐la‐beled cells to the total number of aneuploid cells, or diploid cells in the case of a diploid tumor, ranged from 1.2% to 16.7%; LI and SPF correlated significantly (r = 0.69). In this study, we have demonstrated the feasibility of determining the actively DNA‐synthesizing cells on brush material from lung cancer cells. In addition, some extra information can be obtained about the SPF population, including the fraction of unlabeled SPF, which could be of prognostic significance.
INCA: Software for consort 30 analysis of flow cytometric calcium determinations
Authors: Keij Jan F. , Griffioen Arjan W. , The T. H. , Rijkers Ger T. 
Published: August 2005

AbstractThe INCA program converts Consort 30‐generated fluorescence list mode data collected from Indo‐1‐stained cells to absolute intracellular calcium concentrations (nM Ca2+i). The calcium data are plotted vs. time, allowing the user to analyze the fractions of cells responding to a given stimulus. Converted files can be restored to disk after replacing FL1 and FL2 with time and calcium, respectively, for future analysis.
Automatically inferred markov network models for classification of chromosomal band pattern structures
Authors: Granum Erik , Thomason Michael G. 
Published: August 2005

AbstractA structural pattern recognition approach to the analysis and classification of metaphase chromosome band patterns is presented.An operational method of representing band pattern profiles as sharp edgedidealized profilesis outlined. These profiles are nonlinearly scaled to a few, but fixed number of “density” levels. Previous experience has shown that profiles of six levels are appropriate and that the differences between successive bands in these profiles are suitable for classification. String representations, which focuses on the sequences of transitions between local band pattern levels, are derived from such “difference profiles.”A method of syntactic analysis of the band transition sequences by dynamic programming for optimal (maximal probability) string‐to‐network alignments is described. It develops automatic data‐driven inference of band pattern models (Markov networks) per class, and uses these models for classification. The method does not use centromere information, but assumes the p‐q‐orientation of the band pattern profiles to be known a priori.It is experimentally established that the method can build Markov network models, which, when used for classification, show a recognition rate of about 92% on test data. The experiments used 200 samples (chromosome profiles) for each of the 22 autosome chromosome types and are designed to also investigate various classifier design problems. It is found that the use of a priori knowledge of Denver Group assignment only improved classification by 1 or 2%. A scheme for typewise normalization of the class relationship measures prove useful, partly through improvements on average results and partly through a more evenly distributed error pattern. The choice of reference of the p‐q‐orientation of the band patterns is found to be unimportant, and results of timing of the execution time of the analysis show that recent and efficient implementations can process one cell in less than 1 min on current standard hardware. A measure of divergence between data sets and Markov network models is shown to provide usable estimates of experimental classification performance.
Stylized chromosome images
Authors: Martin Alice O. , Isenstein Barry S. , Thomas Cecil W. , Rzeszotarski Mark S. , Johnson Walter E. 
Published: August 2005

AbstractStylized chromosome images 1) serve as a format to test effects of preprocessing algorithms used in automated karyo‐typing; 2) enhance the ability of humans to perform quantitative analysis of chromosomal aberrations; 3) provide an alternative format for karyotype hard copies produced by automated systems. Stylized chromosomes are two‐dimensional computer‐generated images based on information extracted from one‐dimensional width and density profiles. These profiles correspond to what cytogeneticists observe through the microscope as the shape and banding patterns of stained chromosomes. Stylized presentation sharpens chromosome band boundaries and perimeters, reduces “noise,” and enhances gray level variations, which are difficult to distinguish by humans on photographic or computer generated karyotypes.Karyotyping accuracy using stylized images was used to detect difficult areas for automated chromosome identification. Landmark bands sufficient to classify chromosomes were identified; shapes of chromosomes reflected in width profiles were said to aid classification. A two‐step automated karyotyping strategy proposed is: 1) classify chromosomes by landmarks, minimum information needed for identification; 2) subsequently employ the full banding pattern with maximum resolution to detect aberrations. Stylized images of abnormal chromosomes have potential for testing hypothesis regarding breakpoints and quantitative analysis, but improvements are needed in homologue normalization and definition of termini of chromosomes.
Experience with the athena semi‐automated karyotyping system
Authors: Mayall Brian H. , Tucker James D. , Christensen Mari L. , van Vliet Lucas J. , Young Ian T. 
Published: August 2005

AbstractThe traditional analysis and assembly of metaphase chromosomes into, a karyogram is a slow and tedious process requiring intermediate photographic steps and manual manipulation of the chromosome images. Much of this task is highly repetitive and readily lends itself to partial automation. Semi‐automated karyotyping systems now are being used increasingly in both clinical and research cytogenetic laboratories. Digital image processing techniques are used to capture, manipulate, and make an initial classification of chromosome images. The Athena system uses commercially available components based on a Macintosh II personal computer. Digital image processing procedures automatically isolate chromosome images from the metaphase and arrange them into a karyogram, using information about relative chromosome length, centromeric index, and banding pattern. The operator uses the intuitive graphics interface of the Macintosh computer to monitor each phase of the analysis, to resolve any problems in isolating chromosome images, and to rearrange the individual chromosome images while assembling the final karyogram. Athena is designed as a semi‐automated karyotyping system that is easy to learn and has sufficient power and versatility for routine use in the analysis of human metaphase chromosomes.