Search PubMedSearch

PubMed · 7548698

On plotting renovated samples.

Abstract

In this note we use the Buckley-James method for censored regression in the p sample problem where the samples are subject to right-censoring. The samples are reconstructed so as to remove the effect of censoring, and graphical procedures based on quantiles (such as boxplots) may then be used as a standard data-analytic tool to describe the variable being measured.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

P J Smith. 1995. On plotting renovated samples.. https://pubmed.ncbi.nlm.nih.gov/7548698/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Non-oxidative loss of glutathione in apoptosis via GSH extrusion.

Reduced glutathione (GSH) has been hypothesized to play a role in the rescue of cells from apoptosis, by buffering an endogenously induced oxidative stress. We correlated GSH levels and apoptosis in U937 human monocytic cells induced to apoptosis by different agents. All treatments led to depletion of GSH concomitant with the onset of apoptosis. The loss was due to extrusion of GSH outside the cell, while GSSG was not accumulated in the apoptosing cells, nor was it found in the extracellular medium. Modulation of intracellular GSH level did not influence the overall extent of apoptosis. We conclude that glutathione loss in apoptosis is not necessarily preceded by an oxidative stress, and that GSH depletion alone is not sufficient to lead cells to apoptosis.

Antimetabolites, Antineoplastic

Lack of functional retinoblastoma protein mediates increased resistance to antimetabolites in human sarcoma cell lines.

Growth inhibition assays indicated that the IC50 values for methotrexate (MTX) and 5-fluorodeoxyuridine (FdUrd) in HS-18, a liposarcoma cell line lacking retinoblastoma protein (pRB), and SaOS-2, an osteosarcoma cell line with a truncated and nonfunctional pRB, were 10- to 12-fold and 4- to 11-fold higher, respectively, than for the HT-1080 (fibrosarcoma) cell line, which has wild-type pRB. These Rb-/- cell lines exhibited a 2- to 4-fold increase in both dihydrofolate reductase (DHFR) and thymidylate synthase (TS) enzyme activities as well as a 3- to 4-fold increase in mRNA levels for these enzymes compared to the HT-1080 (Rb+/+) cells. This increase in expression was not due to amplification of the DHFR and TS genes. Growth inhibition by MTX and FdUrd was increased and DHFR and TS activities and expression were correspondingly decreased in Rb transfectants of SaOS-2 cells. In contrast, there was no significant difference in growth inhibition among these cell lines for the nonantimetabolites VP-16, cisplatin, and doxorubicin. A gel mobility-shift assay showed that parental SaOS-2 cells had increased levels of free E2F compared to the Rb-reconstituted SaOS-2 cells. These results indicate that pRB defective cells may have decreased sensitivity to growth inhibition by target enzymes encoded by genes whose transcription is enhanced by E2F proteins and suggest mechanisms of interaction between cytotoxic agents and genes involved in cell cycle progression.

Antimetabolites, Antineoplastic

Cytostatic activity of phenylacetate and derivatives against tumor cells. Correlation with lipophilicity and inhibition of protein prenylation.

The aromatic fatty acid phenylacetate, a common metabolite of phenylalanine, shows promise as a relatively non-toxic drug for cancer treatment. This slowly metabolized fatty acid alters tumor cell lipid metabolism causing, among other effects, inhibition of protein prenylation critical to malignant growth. In pursuit of more potent analogues, we have examined the activity of related compounds against tumor cell lines established from patients with advanced prostatic carcinoma, glioblastomas, and malignant melanoma. Like phenylacetate, derivatives containing alpha-carbon or ring substitutions induced cytostasis and phenotypic reversion at non-toxic concentrations. Potency was correlated with the degree of calculated lipophilicity of the aromatic fatty acid, and the extent of inhibition of protein prenylation. Remarkably, a parallel cytostatic activity was reported in embryonic plant cells, which respond to phenylacetate and its analogues in the same concentration range and the same rank order of lipophilicity. These data suggest that phenylacetate and its analogues may act through common mechanisms to inhibit the growth of vastly divergent, undifferentiated cell types, and provide a basis for the development of new agents for the treatment of human malignancies.

Antimetabolites, Antineoplastic