1,720,984 research outputs found
Effects of Immune Cells on 13762NF Mammary Adenocarcinoma Cell Attachment to Basement Membrane Components
No full textix, 61 p.13762NF mammary adenocarcinoma cell clones MTF7 and
MTF7(Tl1.2) (Fl1.2) were allowed to adhere to extracellular matrix
components. Polymorphonuclear leukocytes (PMN's) were then
introduced in various concentrations using several methods to
examine the effect of these immune cells on attachment of malignant
cells to the basement membrane (BM). Simultaneous PMN and tumor
cell addition to matrices and addition after coincubation at several
physiological temperatures showed no effect on tumor cell adhesion.
PMN's also had no effect on adhesion of MTF7 cells to endothelium.
Matrix pretreatment with PMN's followed by a saline wash prior to
the addition of malignant cells, however, was shown to have a
significant effect on attachment, as the enzymatic action of PMN's
facilitated partial liberation of the matrix. It was therefore
concluded that PMN's are not involved in the step of the metastatic
process involving attachment, but are associated with BM
degradation. In addition, studies to determine the cytolytic activity
of PMN's and natural killer (NK) cells on tumor cell lines of varying
metastatic potential (MTF7, MTF7(Tl1.2), MTC, and MTLn3) were
performed, and it was determined that PMN's and NK's do not
effectively lyse malignant cells in vitro.Upjohn Company, Kalamazoo, M
Analysis of Drug Resistance Patterns in 13762NF Rat Mammary Adenocarcinoma Cell Lines
No full textv, 33 p.To study the effects of cellular subpopulation interactions on
metastatic stability in polyclonal populations of 13762NF rat
mammary adenocarcinoma cell lines, the restriction of clonal
diversity was required. This clonal restriction was achieved
through drug exposure and selection of drug resistant cell lines
(Adr-, DAP-, Oua-, TG- and Vcr-resistant) to act as cell markers.
The objective of this research was to identify the patterns of drug
resistance of these selected MTF7(T35).3 parent and drug-resistant
cell lines using clonogenic colony formation assays to assess
survival after 7 d of continuous drug exposure. Dose-response
curves were constructed from average percent survival data, 90%
lethal dose (LD90) levels were calculated from these dose-response
curves, and levels of drug resistance were determined from these
values. All cell lines were resistant to their respective selecting
agents except the Qua resistant cell line, but the level of resistance
varied when compared to the parental F35.3 cell line. Crossresistance
was observed primarily for the Vincristine sulfate
resistant cell line but to a lesser degree for other cell lines.
Individual resistance patterns of the cell lines did not change in coculture
indicating no cooperativity between cell lines. These cell
lines will be useful for future experiments designed to study the
stability of metastatic potential.Upjohn Company, Kalamazoo, Michigan
A Study of Immune Cell Supernatant-Induced Transient Characteristics of MTF7 and MTF7(T11).2 Mammary Adenocarcinoma Cells
No full textvii, 54 p.13762NF mammary adenocarcinoma cell clone MTF7 and
MTF7(Tl1).2 were grown in various media ( 10%, and 0.125%
Fetal Bovine Serum (FBS), Macrophage-Conditioned Media (MCM),
and Neurtophil-Conditioned Media (PCM)) for 48 hours prior to
interveinous injection into synergeic rats. The rats were
then sacrificed 23 days later, the lungs were removed and the
metastases were counted and measured. No significant
difference was observed between the various treatments. The
actin arrangement in the cells, and the in vitro doubling time
were also unchanged. The tumor cell morphology, however, was
changed. In addition, the in vitro saturation density and the
ftbronectin staining patterns were also altered by various
media. The MCM and the PCM both caused the cells to become
cytostatic
Effect of Polymorphonuclear Cells on Invasive and Metastatic Potentials of 13762NF Rat Mammary Adenocarcinoma Cells
No full textvii, 34 p.The number of circulating activated polymorphonuclear
leukocytes (PMNs) increases in tumor-bearing rats in a manner
corresponding to the metastatic propensity of the tumor cell
inoculated. Because secretion of basement membrane degrading proteinases
was also enhanced, it was proposed that activated PMNs may
play a role in tumor metastasis, particularly tumor cell
extravasation. To test this hypothesis, we measured the
effects of normal PMNs and circulating PMNs isolated from
peripheral blood of tumor bearing rats on the experimental
metastatic and invasive potentials of 13762NF rat mammary
adenocarcinoma cell clones. Circulating PMNs isolated from
MTLn3 tumor-bearing rats increased the invasion potentials of
13762NF rat mammary adenocarcinoma clones in vitro when tested
in the Membrane Invasion Culture System (MICS) using
reconstituted basement membrane as a barrier, and experimental
metastatic potentials in vivo in a dose dependent manner. In
contrast, 'normal' PMNs isolated from peripheral blood, or
proteose peptone-stimulated peritoneal exudate did not alter
these malignant characteristics. When rats received
intravenous co-injections of tumor-elicited PMNs and tumor
cells at an effector:target (E:T) ratio of 50:1 the mean
number of experimental lung metastases rose 23. 2-fold for
weakly metastatic MTLn2, 1.6-fold for moderately metastatic,
highly invasive MTF7 clone, and 3.0-fold for the highly
metastatic MTLn3 clone. In vitro invasive potentials were
measured in MICS with varying E:T ratios (up to 30:1) of
tumor-elicited PMNs and tumor cells. Invasive potential
increased up to 25.5-fold for MTLn2, 36.7-fold for MTF7, and
53.7-fold for MTLn3. These results indicate that PMNs
isolated from MTLn3 tumor-bearing rats have properties that
can contribute to the metastatic potentials of other 13762NF
rat mammary adenocarcinoma clones by assisting their invasion
through a reconstituted basement membrane.Glaxo, Inc. Research Triangle Park, North Carolina
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Mitochondrial haplotype affects histone modification profiles in MNX mice
Full text linkCancer is a growing problem. In the US, cancer is roughly tied with cardiac disease as the leading cause of death. Intriguingly, compared to the proportion of deaths attributable to primary tumors, roughly 90% of all cancer patient morbidity and mortality are a direct result of metastatic disease perturbing normal organ and system function. Research has shown that the propensity to form both spontaneous tumors and metastatic growths is a function of both the nuclear and mitochondrial genomes present within an organism. Specifically, studies have also shown that, when the nuclear background is held constant and the mitochondrial haplotype is varied, there are marked discrepancies in both tumor latency and the average number of metastatic growths observed. To further study the effects of varying the mitochondrial haplotype on cancer progression and metastasis, a unique in vivo model—known as Mitochondrial-Nuclear Exchange (MNX) mice—has been developed. Experiments using this model system further support the notion that mitochondrial haplotype can contribute significantly to tumor latency and the overall of metastatic growths. As an initial line of inquiry, the question was asked as to whether or not differences in gene expression could be present upon changing the mitochondrial haplotype. Given that clear differences in genome-wide expression profiles between wildtype and MNX mice were indeed observed, the next line of inquiry sought to determine whether or not DNA methylation profiles could be regulating the differences in expression. Likewise, significant differences in DNA methylation patterns were established. As a corollary to these findings, the subsequent line of inquiry sought to elucidate whether or not mitochondrial haplotype could influence other potential epigenetic mechanisms responsible for the differences in gene expression profiles. Specifically, given the known link between metabolism and epigenetics, the logical hypothesis of the experiment was simply that the mitochondrial haplotype could potentially able to directly influence the epigenetic process of post-translationally modifying the N-terminal tails of histones in order to affect chromatin state dynamics in the cell. To address this hypothesis, following rigorous antibody validation, a ChIP-Seq experiment comparing wildtype and MNX mice using antibodies against four known histone modifications (H3K4me1, H3K4me3, H3K27me3, and H3K27ac) was conducted. Post-sequencing analysis indicated a selective difference in the overall profile of differentially-bound, post-translationally modified histones, thus supporting the hypothesis that mitochondrial haplotype does directly contribute to overall histone modification profiles. As a next logical step, future work will involve integrating previously generated RNA-Seq, Methyl-Seq, and ChIP-Seq experiments (in combination with extensive metabolome data) to develop hypotheses as to possible causal mechanisms involved in driving the observed differences in tumor latency and metastatic growth. Furthermore, another direction could involve expanding the ChIP-Seq study to include newly characterized acylation (propionylation, butyrylation, succinylation, malonylation, etc.) post-translational modifications which functionally are thought to overlap with acetylation and may more closely link metabolism to overall chromatin state. The results of this research not only contribute to our understanding of how mitochondria participate in influencing the DNA packaging mechanisms involved in regulating chromatin dynamics, but, as our research is not limited to any single form of cancer, has the potential to benefit to all cancer patients
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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