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D M Coder

Publications and source records attributed to D M Coder.

13 recordsLinked to original sources
PubMed1994

Computing the central location of immunofluorescence distributions: logarithmic data transformations are not always appropriate.

The idea of the "average" intensity of immunofluorescence data is often poorly defined, with such terms as average, mean, and peak used interchangeably. In addition, the common use of logarithmic amplifiers with immunofluorescence data further complicates the problem. Log amplifiers permit the display of a wider range of fluorescence intensities. At the same time, they effect a log transformation of the data. This transformation decreases the variance resulting in narrower fluorescence distributions, which are assumed to approximate normal distributions. When the log transform is used, the distribution mean is the geometric mean of the untransformed data, which is computed simply as the mean of the channel values. This mean value serves as a simple indicator of the population center. Despite the prevalence of log transformations in flow cytometry, this transformation may not yield normally distributed immunofluorescence data, whereas the square root or other fractional power transformations can yield normal distributions.

Flow Cytometry↗
PubMed1994

Cell subset (CS) parameter to record the identities of individual cells in flow cytometric data.

The Flow Cytometry Standard (FCS) for cytometric data (Dean et al.: Cytometry 11:323-332, 1990) provides for appending an ANALYSIS section to a data file, but it does not explicitly provide for recording the identities of individual cells. We propose an extension to the FCS definition in order to record the identity of each individual cell in list mode data. In order to do so, one first defines the subpopulations of cells to be identified and one than assigns a number to each defined population. For example, in an analysis in which peripheral blood mononuclear cells are labeled with antibodies to CD3, CD4, and CD8, the "negative" lymphocytes that are labeled with none of the antibodies could be identified as population 1, the CD3-CD4-CD8+ lymphocytes as population 2, etc. As the measured values from each cell are analyzed, the number that identifies the population to which that cell belongs is assigned as the value of an additional parameter. Since this procedure merely adds a new parameter, the only necessary extension to the FCS specification is that a particular name is recognized for this parameter. We propose that CS (abbreviation for cell subset) be recognized as the name and that CS be used as the value for the $PnN (parameter name) keyword in the FCS file TEXT. The CS values that are created can be used to aid in data analysis and can be permanently recorded in a conventional FCS file. A data file that is saved with CS values includes an explicit and integral record of the complete analysis, regardless of the complexity of the analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

CD3 Complex↗
PubMed1991

Increased intracellular calcium is associated with progression of HPV-18 immortalized human keratinocytes to tumorigenicity.

Studies were conducted using normal and human papillomavirus Type 18 (HPV-18) immortalized human keratinocytes to assess possible alterations in the differentiation process as a consequence of increased intracellular calcium concentration. Normal keratinocytes exposed to increased extracellular calcium or the phorbol ester TPA, exhibited terminal differentiation characteristics. However, late passage HPV-18 immortalized keratinocytes (designated FEP-1811) were resistant to such terminal differentiation signals. Flow cytometric analyses of 1811 cells at various stages of passage in culture revealed progressively higher levels of intracellular calcium in the immortalized cells with passage in culture when compared to normal, primary keratinocytes. Furthermore, 1811 cells isolated from tumors which developed in irradiated nude mice contained the highest level of intracellular calcium of all the cells examined. These results suggest that an increase in the concentration of intracellular calcium is associated with progression of HPV-18 immortalized keratinocytes to tumorigenicity.

Calcium↗
PubMed1988

Long-term effects of fermentable fibers on rat colonic pH and epithelial cell cycle.

The long-term effects of fermentable fibers on colonic luminal pH and the epithelial cell cycle were compared in 50 male Sprague-Dawley rats fed either a defined basal fiber-free diet or the basal diet supplemented with 10% pectin, cellulose or guar or with 20% oat bran. After 8 mo, in vivo pH measurements revealed that acidification of luminal contents occurred in the cecum and in mid and distal colons of rats fed fiber-supplemented diets when compared with the fiber-free controls (P less than 0.05). Pectin and guar produced the greatest acidification of luminal contents, the largest increase in cecal surface area and the highest percentage of colonic cells in S-phase, as measured by flow cytometry. In the proximal colon of the pectin group 9.2 +/- 0.5% of cells were in S-phase (6.3 +/- 0.8% with the fiber-free group) (P less than 0.05) and in the distal colon of the guar group 10.9 +/- 1.4% were in S-phase (7.1 +/- 0.5% with the fiber-free group) (P less than 0.05). Even though the most fermentable fibers produced the greatest mitogenic response, there was no site-specific correlation between pH and mucosal cell growth except in the cecum. This suggests that fibers may act as colon cell growth factors by some mechanism other than extracellular pH changes.

Animals↗
PubMed1985

Influence of luminal pH on rat large bowel epithelial cell cycle.

The influence of luminal pH on the colonic epithelial cell cycle was studied by means of dietary modification to produce acidification of colonic contents. Forty male Sprague-Dawley rats were fed one of four diets: defined fiber free, fiber free diluted by either 100 g/kg lactulose or sorbitol, or 25 g/kg of MgSO4. After 2 wk, in vivo pH measurements were recorded at laparotomy under ether anesthesia in the cecum and proximal, mid-, and distal colon. Epithelial cells, isolated from these same regions, were measured for DNA content with flow cytometry in order to determine cell cycle stage. The pH values in all intestinal regions were highest with MgSO4 and then fiber free, sorbitol, and lactulose, the most acidic. In contrast, the percentage of cells in S phase (actively synthesizing DNA) was highest with lactulose and least with MgSO4. There was a significant inverse correlation between luminal pH and percent cells in S phase in the cecum (P less than 0.01), proximal colon (P less than 0.05), and distal colon (P less than 0.01). These results show that acidification of colonic contents by diet modification leads to increased epithelial cell proliferation.

Animals↗
PubMed1976

Midgut volvulus following cesarean section.

Total midgut volvulus and gangrene due to a congenitally elongated mesentery in a 27-year-old primipara occurred 3 days after cesarean section. All of the small bowel distal to the duodenum except for 12 inches of jejunum was resected, and the patient survived. This case and the literature concerning volvulus in pregnancy are reviewed here, and suggestions for prevention and treatment are made.

Adult↗