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Biomedical subjects

C Byrne

Publications and source records attributed to C Byrne.

At least 19 recordsLinked to original sources
PubMed1995

Proportion of breast cancer cases in the United States explained by well-established risk factors.

BACKGROUND: Few estimates of the fraction of cases of breast cancer attributable to recognized risk factors have been published. All estimates are based on selected groups, making their generalizability to the U.S. population uncertain. PURPOSE: Our goal was to estimate the fraction of breast cancer cases in the United States attributable to well-established risk factors (i.e., later age at first birth, nulliparity, higher family income, and first-degree family history of breast cancer), using data from the first National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study (NHEFS), the survey and follow-up of a probability sample of the U.S. population. METHODS: From a cohort of 7508 female participants surveyed in the early 1970s, and followed up between 1982 and 1984 and again in 1987, 193 breast cancer cases were accrued for study. We calculated incidence rates, relative risks (RRs), and population attributable risks (PARs) for breast cancer risk factors and extended our results to the U.S. female population by using sample weights from the NHANES I survey. RESULTS: Our PAR estimates suggest that later age at first birth and nulliparity accounted for a large fraction of U.S. breast cancer cases, 29.5% (95% confidence interval [CI] = 5.6%-53.3%); higher income contributed 18.9% (95% CI = -4.3% to 42.1%), and family history of breast cancer accounted for 9.1% (95% CI = 3.0%-15.2%). Taken together, these well-established risk factors accounted for approximately 47% (95% CI = 17%-77%) of breast cancer cases in the NHEFS cohort and about 41% (95% CI = 2%-80%) in the U.S. population. CONCLUSIONS: The RRs for most of these risk factors were modest, but their prevalence as a group was high, leading to estimates that suggest that a substantial proportion of breast cancer cases in the United States are explained by well-established risk factors. IMPLICATIONS: Elucidation of the determinants underlying recognized factors and study of other factors that may confer risk or protection are needed in efforts to advance understanding of breast cancer etiology and to aid in devising strategies for prevention.

Adult↗
PubMed1995

Mammographic features and breast cancer risk: effects with time, age, and menopause status.

BACKGROUND: Mammographic images from women with a high proportion of epithelial and stromal breast tissues are described as showing high-density parenchymal patterns. Most past studies that noted an increase in breast cancer risk associated with mammographic parenchymal patterns showing high density either 1) lacked information on other breast cancer risk factors, 2) were too small, or 3) included insufficient follow-up time to adequately resolve persisting doubts whether mammographic features are "independent" measures of breast cancer risk and not a detection artifact. PURPOSE: The purpose of this study was twofold: 1) to evaluate the associations between mammographic features and other breast cancer risk factors and 2) to assess effects of mammographic features on breast cancer risk by time, age, and menopause status. METHODS: To address these questions, we analyzed detailed information from a large, nested case-control study with 16 years of follow-up. This study used information from both screening and follow-up phases of the Breast Cancer Detection Demonstration Project, a nationwide program that offered annual breast cancer screening for more than 280,000 women from 1973 to 1980. Mammographic features were assessed from the base-line screening mammographic examination for 1880 incident case subjects and 2152 control subjects. Control subjects were randomly selected from women of the same age and race as each case subject. Control subjects attended the same screening center as the case subject and were free of breast cancer at the case subject's date of diagnosis. Odds ratios (ORs) with 95% confidence intervals (CIs) provided estimates of the relative risk of breast cancer. RESULTS: Mammographic features were associated with known breast cancer risk factors. However, the high-density parenchymal pattern effects were independent of family history, age at first birth, alcohol consumption, and benign breast disease. The increase risk for women with Wolfe's two high-density parenchymal patterns, P2 (OR = 3.2; 95% CI = 2.5-4.0) and Dy (OR = 2.9; 95% CI = 2.2-3.9), was explained primarily by measured percent of the breast with dense mammographic appearance. Compared with women with no visible breast density, women who had a breast density of 75% or greater had an almost fivefold increased risk of breast cancer (95% CI = 3.6-7.1). These effects persisted for 10 or more years and were noted for both premenopausal and postmenopausal women of all ages. CONCLUSIONS: Of the breast cancer risk factors assessed in the participants, high-density mammographic parenchymal patterns, as measured by the proportion of breast area composed of epithelial and stromal tissue, had the greatest impact on breast cancer risk. Of the breast cancers in this study, 28% were attributable to having 50% or greater breast density.

Age Factors↗
PubMed1995

Lymphoid enhancer factor 1 directs hair follicle patterning and epithelial cell fate.

T cell-specific transcription factor (TCF-1) and lymphoid enhancer factor 1 (LEF-1) have been implicated exclusively in the regulation of T cell-specific genes. The only adult tissue other than thymus known to express these factors is spleen and lymph node, which contain low levels of LEF-1 and no TCF-1. We noticed that genes involved in hair-specific gene expression possess LEF-1/TCF-1 consensus motifs located in similar positions relative to their TATA box. We show that of the two factors only LEF-1 is expressed in hair follicles; it can be cloned in both splice forms from human skin keratinocytes and it can bind to these sites in the hair promoters. We show that LEF-1 mRNA is present in pluripotent ectoderm, and it is up-regulated in a highly restricted pattern just before the formation of underlying mesenchymal condensates and commitment of overlying ectodermal cells to invaginate and become hair follicles. New waves of ectodermal LEF-1 spots appear concomitant with new waves of follicle morphogenesis. To test whether LEF-1 patterning might be functionally important for hair patterning and morphogenesis, we used transgenic technology to alter the patterning and timing of LEF-1 over the surface ectoderm. Striking abnormalities arose in the positioning and orientation of hair follicles, leaving a marked disruption of this normally uniform patterning. This provides the first direct evidence that ectodermal cues are critical in establishing these developmental processes, which at later stages are known to be influenced by underlying mesenchyme. Remarkably, elevated LEF-1 in the lip furrow epithelium of developing transgenic animals triggered these cells to invaginate, sometimes leading to the inappropriate adoption of hair follicle and tooth cell fates. Collectively, our findings demonstrate that ectodermal expression of LEF-1 plays a central role in gene expression, pattern formation, and other developmental processes involving epithelial-mesenchymal associations.

Alternative Splicing↗
PubMed1995

Exploring the lived experiences of psychiatric nursing students through self-reflective journals.

This study explores the use of journals to identify important issues facing nursing students when learning in a psychiatric setting. During a 13-week psychiatric clinical experience, 18 third-year students kept journals describing the most significant event that occurred each week, reflecting on the impact and accompanying attitudes of that event. Throughout the clinical experience, the nursing faculty read the students' journals and provided written feedback on a bi-weekly basis. Major themes that students wrote about in their journals were identified. These included: meaningful learning, issues of the novice, relationships, control, self-reflection, and identification with clients. Keeping a journal provided the students with an opportunity to become more self-reflective in their practice. The issues identified by students in their journals may assist nurse educators to anticipate the learning needs of their students in psychiatry.

Female↗
PubMed1995

Primary structure of the V3 region of gp120 from sequential human immunodeficiency virus type 1 isolates obtained from patients from the time of seroconversion.

V3 loop sequences were compared from 5 human immunodeficiency virus type 1 (HIV-1)-infected patients over time. Three patients remained asymptomatic and 2 became symptomatic with large decrease in CD4 cell counts. The patient isolates were previously evaluated for phenotypic and antigenic properties and had different sensitivities to serum neutralization and changes in phenotype. This study showed a number of amino acid changes for the 2 symptomatic patients, each of whom progressed to AIDS during the study. The only amino acid substitution consistently associated with reduced CD4 cell counts, cytopathic effect, and progression to AIDS was Arg at position 11. Specific amino acid changes could not be correlated with increasing serum neutralization resistance or cytotropism changes. Increased loop charge was associated with a switch from macrophage to T cell tropism and a decrease in the number of CD4 cells. The study shows the importance of naturally occurring mutations in the V3 loop in controlling the biologic properties of HIV-1.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Mediation by 5-hydroxytryptamine2B receptors of endothelium-dependent relaxation in rat jugular vein.

1. An 'atypical' 5-HT2 receptor which is located on the endothelium of rat jugular vein has been described. In the present study we have further defined the nature of the 5-HT2 receptor subtype present in this preparation. 2. In experiments conducted in the presence of ketanserin to preclude involvement of 5-HT2 receptors, the mixed 5-HT2B/2C antagonist, SB 200646, acted as an antagonist of 5-HT at the endothelial 5-HT receptor (pA2 = 7.2). Yohimbine, which exhibits negligible affinity for rat 5-HT2C receptors but has high 5-HT2B receptor affinity, acted as a potent but non-surmountable antagonist (pA2 > or = 7.3) in rat jugular vein. Neither yohimbine nor SB 200646 affected endothelium-dependent relaxations induced by carbachol. 3. Mianserin also acted as a surmountable antagonist (pA2 = 7.3) and the 5-HT2B agonist, BW 723C86, acted as a potent partial agonist (pEC50 [95% C L], intrinsic activity +/- s.e. mean = 7.9 [7.6-8.3], 0.84 +/- 0.04). Responses to BW 723C86 were antagonized by SB 200646 (0.3 microM) yielding an 'apparent' pA2 [95% CL] of 7.03 [6.76-7.32]. 4. These data are consistent with the presence of 5-HT2B receptors mediating endothelium-dependent relaxation of rat jugular vein.

Animals↗
PubMed1995

Hope and schizophrenia: clinicians identify hope-instilling strategies.

Nurses have many opportunities to assist individuals with schizophrenia because of the frequency and nature of their contacts. The nurses in this study believed that they can make a difference and can identify hope-instilling strategies. Strategies for rehabilitation include assisting persons with schizophrenia to set goals, seeing them as people, and joining with them on their journey of recovery. Recognizing that the establishment of the relationship is central in assisting the development of client hope, and (hopefully) eventual recovery, may help nurses to persevere despite what may be a challenging and lengthy process.

Adaptation, Psychological↗
PubMed1994

Menopausal estrogen and estrogen-progestin replacement therapy and risk of breast cancer (United States).

This study examines the relationship between menopausal estrogen and estrogen-progestin replacement therapy and risk of breast cancer, focusing on whether associations differ according to whether the tumors are in situ or invasive. Data are from a prospective study conducted 1980-89 on 49,017 selected participants in the Breast Cancer Detection Demonstration Project, a five-year screening program conducted between 1973 and 1980 in the United States. Overall, the rate ratio for estrogen-only use compared with no-hormone use was 1.0, and that for the estrogen-progestin combination was 1.2 (95 percent confidence interval [CI] = 1.0-1.6). However, the associations differed according to whether the tumors were in situ or invasive. The rate ratios of in situ breast cancer associated with use of estrogens alone and the combination regimen were 1.4 (CI = 1.0-2.0) and 2.3 (CI = 1.3-3.9), respectively. Duration of estrogen-only use also was associated with risk of in situ tumors, with users for 10 or more years at twice the risk of nonusers (P-value for trend test = 0.02). Duration of use was not associated with risk of invasive cancer. Our results are consistent with the hypothesis that hormone replacement therapy is related to earlier-stage breast cancer; however, the possibility that the results reflect increased breast cancer surveillance among those taking hormones cannot be ruled out.

Adult↗
PubMed1994

The epidermis: rising to the surface.

At the skin surface, the epidermis serves an important protective function which it manifests by building an extensive cytoskeletal architecture of keratin filaments, spanning from the nuclear envelope to hemidesmosomes and desmosomes. Recent studies on epidermal proteins and their interactions have provided insights into human skin diseases, including genetic disorders of keratins, laminins, and collagen. Explorations into the regulatory mechanisms underlying epidermal genes have underscored the importance of transcription factors AP-1 and AP-2, retinoic acid receptors, and POU proteins. Transgenic and gene ablation experiments on TGF-alpha and TGF-beta genes have yielded clues as to how the epidermis maintains a balance of growing and differentiating cells.

Animals↗
PubMed1994

Neutralizing antibodies against sequential autologous human immunodeficiency virus type 1 isolates after seroconversion.

The emergence of human immunodeficiency virus type 1 (HIV-1) variants with different sensitivities to serum neutralization and biologic phenotype was studied for 2-5 years after primary HIV-1 infection in 5 subjects. In 3 subjects, the initial virus isolate from seroconversion could be neutralized by autologous serum, but isolates obtained at two subsequent times exhibited reduced sensitivity to serum neutralization, decreased replication in primary macrophages, and increased ability to induce syncytia. Two of these 3 subjects progressed to AIDS and died. Sequential virus isolates from the other 2 subjects showed variability in sensitivity to serum neutralization or biologic features. These patients remained relatively stable in clinical status. Thus, viruses isolated at seroconversion appear to be either non-syncytium-inducing, strong macrophage-tropic, serum neutralization-sensitive phenotypes with stable clinical status or to have escaped neutralization by autologous sera over time, have reduced macrophage tropism and increased syncytia formation, and be associated with disease progression.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Pathways into the work force: antecedents of school and work force status.

OBJECTIVE: The study aim was to identify risk factors for specific pathways into the work force using data from the Ontario Child Health Study Follow-up. METHOD: Potential predictor variables were derived from data collected in 1983 on adolescents aged 13 to 16 years. The subjects were followed up 4 years later and the school/work force outcome was determined. Bivariate and multivariate statistical analyses were used to identify variables with a strong independent association with this outcome. RESULTS: Subjects in the work force were four times more likely than those attending school to have come from a low-income family and at least two times more likely to have a family background of low maternal education, to have failed a grade, or to have used substances heavily during early adolescence. Subjects with two or more of these risk factors were likely to be in part-time work or unemployed. CONCLUSIONS: Preventive interventions should be targeted at children from poor families, or who fail at school, or show early onset of substance abuse and other deviant behaviors. Studies are needed to further elucidate the relationship between these risk factors and pathways into the work force and beyond.

Adolescent↗
PubMed1994

Programming gene expression in developing epidermis.

As the major proteins of adult keratinocytes, keratins provide biochemical markers for exploring mouse epidermal embryogenesis. Here, we used a modified method of whole-mount in situ hybridization to track skin-specific expression of endogenous keratin mRNAs throughout embryogenesis. To monitor transcriptional regulation, we coupled this with beta-galactosidase expression of a human epidermal keratin promoter-driven transgene. These studies have radically changed our perception of how the program of gene expression becomes established during epidermal development. Specifically, we have discovered that (1) basal keratin (K5 and K14) genes are first detected at E9.5 in a highly regional fashion, and surprisingly as early as the single layered ectodermal stage; (2) the early patterns do not correlate with morphogenesis per se, but rather with regional variations in the embryonic origin of underlying mesenchyme, supporting morphogenetic criteria that early inductive cues are mesenchymal; (3) epidermal keratin genes are expressed in periderm, supporting the notion that this layer arises from ectodermal stratification, even though it is simple epithelial-like in morphology and is subsequently sloughed during development; (4) later embryonic patterns of K5 and K14 gene expression parallel proliferative capacity and not stratification; and (5) K1 and K10 mRNAs are first detected as early as E13.5, and their patterns correlate with differentiation and not stratification. These patterns of epidermal gene expression led us to explore whether potential transcriptional regulators of these genes are expressed similarly. We show that AP2 (but not Sp1) cRNAs hybridize in a pattern similar to, but preceding that of basal keratin cRNAs. Finally, using gene expression in cultured cells, we demonstrate that AP2 has a strong inductive effect on basal keratin expression in a cellular environment that does not normally possess AP2 activity.

Adaptor Protein Complex 2↗
PubMed1994

The defining characteristics of support. Results of a research project.

Support is a central concept in nursing practice; not only for psychiatric nurses, but for all nurses. Yet, the ambiguity about the definition of support is troubling. More importantly, nurses are "doing things" to and for patients, but are these interventions truly supportive? What kinds of support do our patients want and need? As nursing advances towards a scientific basis for practice, we must be clear about the what and why of our actions (Sebastian, 1990). As nurses become more outcome oriented, we must know what patients value in their treatment. This study is an initial attempt to clarify for psychiatric nurses the concept of support; may it be the first of many.

Adult↗
PubMed1994

Devising a model health visitor supervision process.

Supervision has long been established in social work practice. Health visiting has no such tradition, yet they too need expert, specialist support, education and management in child protection, argues Christine Byrne. Here she describes health visitors' perceptions of their need for and function of supervision, and a project successfully to pilot-and subsequently implement-a wider health visitor supervision process for child protection work.

Child↗