Biomedical subjects

B Hunsberger

Publications and source records attributed to B Hunsberger.

9 recordsLinked to original sources

PubMed2003

Effects of resolution reduction on data analysis.

BACKGROUND: There is often a need in flow cytometry to display and analyze histograms at resolutions lower than those native to the data. It is common, for example, to analyze DNA histograms at 256-channel resolution, even though the data were acquired at 1,024 channels or more. The most common method for reducing resolution, referred to as the consecutive summation (CS) method, can introduce distortions into the shape of histograms. Peaks that were symmetric in the original data can become skewed in the reduced-resolution histogram. Data analysis can be negatively affected by the distortions produced by reducing the histogram resolution. An alternative technique for reducing histogram resolution, the unbiased summation (US) method, minimizes shape distortion. This paper describes the US method and examines the benefits it provides in the analysis of DNA histograms. METHODS: Reduced chi-square (RCS) was used to measure the response to three experimental variables in the least-squares analysis of simulated DNA histograms. For each variable (the percentage of coefficient of variation [%CV], number of events, and mean position of the G1 distribution), a test data set of 1,000 histograms was generated at 1,024-channel resolution. Histogram resolutions were reduced with each method and then analyzed with ModFit LT cell-cycle analysis software (Verity Software House, Topsham, ME). S-phase error and processor computation time of each method also were evaluated. A Monte Carlo experiment was performed to compare CS and US methods to theoretically correct reductions. RESULTS: CS method analysis results were negatively affected by changes in %CV, number of events, and G1 peak position. The US method produced consistently lower RCS values (more accurate results) within the tested ranges. The US method eliminated bias in S-phase error and had negligible impact on analysis processing speed. It improved RCS values 44.50% on average (P < 0.0002) with actual DNA histograms. Whereas the CS method became less accurate (chi-square test) as the amount of reduction increased, the US method was unaffected, producing consistently better results. CONCLUSIONS: The US method is recommended for reducing histogram resolution in modeling applications such as DNA cell-cycle analysis. It may have implications in other areas of flow cytometric data analysis.

Algorithms↗

PubMed2001

Optimizing flow cytometric DNA ploidy and S-phase fraction as independent prognostic markers for node-negative breast cancer specimens.

Developing a reliable and quantitative assessment of the potential virulence of a malignancy has been a long-standing goal in clinical cytometry. DNA histogram analysis provides valuable information on the cycling activity of a tumor population through S-phase estimates; it also identifies nondiploid populations, a possible indicator of genetic instability and subsequent predisposition to metastasis. Because of conflicting studies in the literature, the clinical relevance of both of these potential prognostic markers has been questioned for the management of breast cancer patients. The purposes of this study are to present a set of 10 adjustments derived from a single large study that optimizes the prognostic strength of both DNA ploidy and S-phase and to test the validity of this approach on two other large multicenter studies. Ten adjustments to both DNA ploidy and S-phase were developed from a single node-negative breast cancer database from Baylor College (n = 961 cases). Seven of the adjustments were used to reclassify histograms into low-risk and high-risk ploidy patterns based on aneuploid fraction and DNA index optimum thresholds resulting in prognostic P values changing from little (P < 0.02) or no significance to P < 0.000005. Other databases from Sweden (n = 210 cases) and France (n = 220 cases) demonstrated similar improvement of DNA ploidy prognostic significance, P < 0.02 to P < 0.0009 and P < 0.12 to P < 0.002, respectively. Three other adjustments were applied to diploid and aneuploid S-phases. These adjustments eliminated a spurious correlation between DNA ploidy and S-phase and enabled them to combine independently into a powerful prognostic model capable of stratifying patients into low, intermediate, and high-risk groups (P < 0.000005). When the Baylor prognostic model was applied to the Sweden and French databases, similar significant patient stratifications were observed (P < 0.0003 and P < 0.00001, respectively). The successful transference of the Baylor prognostic model to other studies suggests that the proposed adjustments may play an important role in standardizing this test and provide valuable prognostic information to those involved in the management of breast cancer patients.

Breast Neoplasms↗

PubMed2001

DNA and cell cycle analysis as prognostic indicators in breast tumors revisited.

Both DNA ploidy and S-phase ploidy are promising prognostic factors for node-negative breast cancer patients. Based largely on the analysis of one large study, much of the reported problems with these factors have been caused by some unappreciated complexities in categorizing DNA ploidy into low- and high-risk groups and the lack of some necessary adjustments to eliminate unwanted correlations between DNA S-phase and ploidy. When both DNA ploidy and S-phase are compensated properly, they become independent prognostic markers, forming a powerful prognostic model.

Breast Neoplasms↗

PubMed2000

Becoming a parent: the relation between prenatal expectations and postnatal experience.

The relationship between individuals' prenatal expectations about parenthood and their postnatal experience of parenthood was examined. Seventy-three primiparous couples were interviewed during the 3rd trimester of pregnancy and asked open-ended questions regarding their expectations. A content analysis of these expectations identified several themes. A cluster analysis, using these themes as variables, identified 3 clusters of women labeled prepared, fearful, and complacent and 4 clusters of men labeled prepared, fearful, complacent, and mixed. Postnatal comparisons indicated that women and men in the prepared cluster generally demonstrated better adjustment than did individuals in the other clusters. Results are discussed in terms of the content of expectations about parenthood, gender differences in these expectations, and the association between prenatal expectations and postnatal experiences.

Adult↗

PubMed2000

Thinking ahead: complexity of expectations and the transition to parenthood.

This study examined the integrative complexity of thinking in individuals making the transition to parenthood, and the relationship between complexity and adjustment during this period. Sixty-nine couples were interviewed 3 months before their babies were born, and 6 months after the birth. The prenatal interview focussed on individuals' expectations about what it would be like being a parent; the postnatal interview focussed on individuals' actual experiences as parents. In addition, participants completed measures of depression, self-esteem, and marital satisfaction after each interview, and a measure of stress after the 6-month postnatal interview. Both men and women demonstrated a significant increase in the complexity of their thinking from the prenatal to the postnatal interview, with women demonstrating higher levels of complexity at both times. In addition, women with more complex expectations demonstrated better adjustment after their babies were born than did women with simpler expectations; these results were not obtained for men. Results are discussed with regard to the way in which thinking about the self changes as one negotiates major life transitions, and the way in which complex thinking can help counter some of the stresses that individuals may experience at these times.

Adaptation, Psychological↗

PubMed1996

Moral and social reasoning and perspective taking in later life: a longitudinal study.

In this study 27 older adults (ages 64-80) and 23 middle-aged adults (ages 35-54) were tested for moral stage, integrative complexity of social reasoning, and perspective-taking levels twice over a 4-year period. Moral reasoning stage levels did not change over time for either age group. Older adults, but not the middle-aged, showed a significant decline over time in level of moral perspective taking. Complexity of reasoning about several interpersonal social issues declined modestly in both age groups. More social-cognitive support, a higher education level, and better self-reported health were all found to be protective factors in forestalling declines in mature adults' sociocognitive reasoning, consistent with other research on cognitive measures in later life.

Adult↗

PubMed1991

Four pathways in the analysis of adult development and aging: comparing analyses of reasoning about personal-life dilemmas.

Four systems for analyzing thinking about 2 personal-life dilemmas, as discussed by 29 men and 35 women (ages 35-85), were compared. Kohlberg's (1976) moral judgment stages, Kegan's (1982) ego-development stages, Gilligan's (1982) moral orientation system, and Suedfeld and Tetlock's (1977) integrative complexity scoring were used. Subjects completed Kohlberg's (Colby & Kohlberg, 1987) standard moral judgment measure, a self-concept description, and several questionnaires. The Kohlberg, Kegan, and integrative complexity codings of the dilemmas were positively related to each other and to the standard Kohlberg moral stage scores. There were no age-group differences and few gender differences on the measures. However, education, role-taking skills, and greater sensitivity to age changes in the self positively predicted higher stage scores across maturity.

Adaptation, Psychological↗

PubMed1990

Reasoning about the self and relationships in maturity: an integrative complexity analysis of individual differences.

This study examined age (35-55 versus 65-85), gender, and self-concept-orientation differences in reasoning about the self, relationships, and morality, on the basis of the theorizing of Gilligan (1982). Participants were interviewed about general relationship issues, a specific relationship, and about the self. Reasoning was scored for integrative complexity (Suedfeld & Tetlock, 1977). Life experience measures and the standard Kohlberg justice reasoning index were obtained. Results showed gender differences in the connectedness of the self-concept for middle-aged, but not older, adults. No age or gender differences in the complexity of relationship reasoning or in justice reasoning were found. Those with more connected self-concepts reasoned in more complex ways about relationships and about the self.

Adaptation, Psychological↗

PubMed1985

Religion, age, life satisfaction, and perceived sources of religiousness: a study of older persons.

Eighty-five persons aged 65 to 88 years participated in this interview study of three issues. The present study supported previous findings of a tendency toward increased religiosity in older age. This was tempered, however, by the finding that, although highly religious older persons tended to report an increase in religiousness over the course of their lives, respondents who were low in religiosity tended to report a decrease. These two groups reported that before the age of 20 a relatively small difference in religiosity existed but by old age this difference had become substantial. Second, there was evidence of a low to moderate positive relationship between religiosity and life satisfaction. Finally, mothers were reported to have had the strongest proreligious influence, although both parents were generally perceived to be important influences in religious development.

Age Factors↗