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L Ayres

Publications and source records attributed to L Ayres.

At least 19 recordsLinked to original sources
PubMed2025

A single-locus quantitative genetic model incorporating DNA methylation.

We describe a single-locus quantitative genetic model that incorporates effects due to DNA methylation. Extending Fisher's decomposition of the genotypic value, we distinguish two quantities to predict an individual's phenotypic or genetic values: the "basic genetic value" and the "expressed genetic value". We show how these quantities relate to the concept of breeding value and derive their corresponding formulas, along with those for phenotypic variance and covariance between relatives. The resulting parameters are influenced by several factors, including the population distribution of DNA methylation levels, the functional relationship between methylation and phenotype, the magnitudes of genetic and methylation effects, and allele frequencies. We show that under the conditions modeled, the presence of DNA methylation does not bias estimated breeding values.

DNA Methylation↗
PubMed2000

Narratives of family caregiving: four story types.

Researchers across disciplines have recognized considerable individual variation among caregivers in their response to the experiences of caregiving. One explanation for individual variation is that caregivers make different meanings from caregiving even under externally similar circumstances. This paper describes findings from a study that combined two qualitative strategies, across-case, thematic analysis and within-case, narrative analysis, to investigate meaning in accounts of family caregiving. Themes identified in the across-case analysis were interpreted in the context of patterns identified in the narrative analysis, as well as in the overall framework of caregivers' process of making meaning. Caregivers in this study told four types of stories: stories of ideal lives, stories of ordinary lives, stories of compromised lives, and ambiguous stories. Characteristics of each story type are described, and an example of an ambiguous story is also included as an illustration of the method. Findings suggest a new approach to understanding family caregiving that incorporates the diverse meanings caregivers make of their often similar experiences.

Aged↗
PubMed2000

Narratives of family caregiving: the process of making meaning.

Researchers across disciplines have identified meaning as an important influence on family caregivers' responses to caregiving. This Paper describes a qualitative inquiry into the process of making meaning used by caregivers. This process includes three interrelated components: expectations, explanations, and strategies. Caregivers used this process to make sense of caregiving in the larger context of their lives, interpreting both the experience of caregiving and their own affective responses. Expectations included predictions for events or behaviors. Explanations incorporated both moral and practical reasoning to account for discrepancies between predicted and actual outcomes. Strategies, actions taken to actualize expectations, were influenced both by desired outcomes and by the presence of an underlying explanation for a given course of action. This paper provides some narrative examples of the process of making meaning to illustrate the components of making meaning and the interrelationships among them.

Aged↗
PubMed1998

"Not as bad as it could have been": assessing and mitigating harm during research interviews on sensitive topics.

Research on sensitive subjects such as perinatal loss places participants at particular risk for psychological distress. Although authors have discussed strategies for minimizing distress during interview research, less is known about the ways participants communicate and investigators respond to psychological pain incurred during the interview itself. Therefore, we describe both verbal and nonverbal indicators of distress during a phenomenological study on perinatal loss. We also offer suggestions for interviewers on ways to minimize participants' discomfort. We believe this account will help other researchers identify and reduce respondent distress during their own research.

Adaptation, Psychological↗
PubMed1997

Endings, secrets, and silences: overreading in narrative inquiry.

Qualitative researchers seek to understand the words of the people they interview and may use narrative inquiry to find meaning in the stories told by research participants. Narrative inquiry entails "overreading," a sensitivity to unspoken or indirect statement, which is central to interpretation. Some of the tools of the literary overreader are applied to two research interviews, particularly as they direct readers to attend to inconsistencies, endings, repetitions, and silence. Because overreading is also intrusive, we conclude with some considerations about how far the overreader of the research may legitimately go.

Aged↗
PubMed1996

Virtual text and the growth of meaning in qualitative analysis.

Qualitative researchers frequently analyze data in the form of narrative, such as responses to open-ended interview questions. Researchers acknowledge the validity of more than one interpretation of the same narrative but, to date, have offered little justification for multiple valid interpretations. A concept for literary theory, "the virtual text" is presented to help explain the mechanism of multiple interpretations and provide a justification for their validity. An example from the first author's research is provided.

Humans↗
PubMed1994

Polonium metabolism in adult female baboons.

The biokinetics of polonium in nonhuman primates (Papio anubis) has been studied after intravenous injection of 210Po citrate. The urinary excretion of polonium in the baboon could be described by a single exponential function with a half-time of 15.6 days. Excretion fractions of polonium were found to be markedly different from those reported for other species, including humans. Polonium-210 was found to be distributed throughout the soft tissues of the baboon with 29% of the injected polonium being deposited in liver, 7% in kidneys and 0.6% in spleen. Retention of polonium in all tissues exhibited single exponential functions; however, the biological half-times were variable, ranging from 15 to 50 days.

Animals↗
PubMed1993

Observations on the commercial production of ostrich (Struthio camelus) in the United Kingdom: rearing of chicks.

Two sets of ostrich eggs (60 and 120 eggs) were imported into the United Kingdom under class 1 quarantine restrictions. The eggs were incubated and observations were made on the growth, survival and sex ratio of the chicks hatched. The chicks decreased in weight for five days after hatching before they began a sustained period of exponential growth. They reached a liveweight of 4 kg five weeks after hatching. Female chicks grew significantly faster than male chicks. The survival rates of the chicks to three months of age were 66.7 per cent and 78.3 per cent, respectively, for the two sets of eggs, and mortality restricted mainly to the first four weeks of rearing. All the birds which died showed poor rates of growth before they died. The sex ratio of both groups was skewed 2:1 towards males.

Animal Husbandry↗
PubMed1993

Observations on the commercial production of ostrich (Struthio camelus) in the United Kingdom: incubation.

Two sets of ostrich eggs (60 and 120 eggs) were imported into the United Kingdom under class 1 quarantine restrictions. Single stage incubation was carried out and the eggs were weighed before and during incubation in order to control weight loss. In the two hatches the weight losses during the incubation of viable eggs were 13.4 per cent and 11.4 per cent, respectively. The development of the eggs was followed by candling and although only dark shadows were observed a pattern could be recognised. For the first set of eggs the average length of incubation was 45.9 days with an interval of 12.7 hours between pipping and hatching. The second set of eggs was incubated at higher temperatures than the first and the main incubation period was 43.3 days with hatching 19.2 hours after pipping. Larger eggs took longer to hatch.

Animals↗
PubMed1993

Sibling perspectives on schizophrenia and the family.

Intensive audiotaped interviews with 14 adult siblings of schizophrenia patients were used to explore their experiences. Interviews focused on the ways adult siblings define and experience their sibling's mental illness and their participation in illness management. Cross-case analysis revealed that recognition of schizophrenia in a brother or sister was characterized by a pivotal, reorganizing event that redefined behavior previously viewed as difficult or different. Subjects' approach to the sibling's illness reflected three distinct patterns: collaborative, crisis-oriented, and detached. The impact of a mentally ill brother or sister on subjects' lives ranged from pervasive to discrete and was seen as emanating from the family and the sibling, but in different ways. These findings can help sensitize clinicians to the complex nature of sibling experiences as well as to the needs of siblings and their families.

Adult↗
PubMed1993

Triangulation in qualitative research: evaluation of completeness and confirmation purposes.

The term triangulation has been applied to research strategies intended to serve two distinct purposes, confirmation and completeness. Many researchers who claim to have used a triangulated approach fail to provide evidence to show that their approach contributed to either confirmation or completeness of the data set. This paper reviews these distinct purposes and describes how triangulation of qualitative and quantitative methods was built into a study to achieve them. Analysis of data related to a single construct illustrates how data generated by qualitative and quantitative methods can provide both convergent validity and a broader understanding of one's subject matter.

Adaptation, Psychological↗
PubMed1992

[Typing of human papillomavirus (HPV) in the male and female genitalia].

Diagnosis and typing of HPV was started in November 1990 at the Virology department of the National Health Institute, Lisbon. Eighty one samples from 70 patients were studied, 57 from women observed at the cervico-vulvar out patient unit of the Gynecology department of Sta Maria Hospital, Lisbon, and 13 from male contacts of some of these women. Forty nine women (86%) had colposcopic, histological or cytological evidence of HPV infection. Eleven men (85%) have clinical signs of infection and 2 (15%) had had sexual intercourse with infected partners with clinical evidence of infection. HPV DNA was detected in 43 patients (61%). Forty two were infected with HPV 6/11 (98%) and one with HPV 16 (2%). These preliminary results suggest that genital infection by HPV must also be considered a public health problem in the field of sexually transmitted diseases in Portugal.

Adolescent↗
PubMed1990

Multicenter evaluation of a new recombinant enzyme immunoassay for the combined detection of antibody to HIV-1 and HIV-2.

A newly developed recombinant antigen-based anti-HIV-1/HIV-2 enzyme immunoassay (Abbott Recombinant HIV-1/HIV-2 EIA) was evaluated against a second generation anti-HIV-1 EIA (Abbott Recombinant HIV-1 EIA). Five thousand and twenty-nine sera from European blood donors and 403 sera from central African blood donors were used in the evaluation, along with four panels and one cohort. The panels included 99 'problem' sera, 733 sera with antibodies to HIV-1 from asymptomatic people and from patients at different disease stages, 25 serial bleeds from five plasmapheresis donors seroconverting for antibodies to HIV-1, and 202 sera with antibodies to HIV-2 collected from healthy and diseased people of European or west African origin. In addition, 734 sera collected from a west African cohort were tested. Using Western blot as the reference standard, the specificity obtained by the recombinant anti-HIV-1 EIA (HIV-i EIA) was 99.90% [99.81-99.99%; 95% confidence limits (95% CL)] with European blood donor sera; 99.50% (98.78-100%) with Central Africa blood donor sera; 92.93% (87.78-98.08%) with 'problem' sera and 99.43% (98.87-100%) with sera from a west African cohort. Using the same samples, the recombinant anti-HIV-1/HIV-2 EIA (HIV-1/HIV-2 EIA) yielded a specificity of 99.84% (99.73-99.95%), 99.50% (98.78-100%), 95.96% (92.00-99.92%) and 98.58% (97.69-99.47%), respectively. All 776 Western blot-confirmed anti-HIV-1 sera were reactive in both EIAs, and the EIA-reactive samples from seroconverting plasma donors were always observed for both assays in the same serial bleed. For HIV-2, the HIV-1 EIA yielded an overall sensitivity of 75.83% (69.93-81.72%) compared with 99.53% (98.58-100%) for HIV-1/HIV-2 EIA. The addition of a recombinant env-protein of HIV-2 to the recombinant env and core proteins of HIV-1 on the solid phase of HIV-1 EIA improved the detection of anti-HIV-2 while preserving the assay's overall specificity and sensitivity for the detection of anti-HIV-1.

AIDS Serodiagnosis↗
PubMed1989

Implications of utility and deontology for the clinical nurse specialist.

Faced with prospective payment plans and personnel shortages nurses in advanced clinical practice are under pressure to find practical solutions. These solutions may reflect the institutional philosophy of utility rather than the traditional nursing ethic of deontology, illustrating the need to examine the differences between utilitarian and deontological principles as they affect nursing practice. This paper discusses deontology and utility as they apply to nursing practice, considers how these different philosophical positions may affect advanced practitioners, and describes the current status of ethics in nursing.

Ethics, Nursing↗
PubMed1989

The importance of acid digestion of urine prior to spontaneous deposition of 210Po.

Historically, radiochemical analysis of 210Po in urine has used spontaneous deposition of the nuclide directly from raw urine onto a suitable metal disc. Consequently, the urinary excretion fraction for Po in some current metabolic and dosimetric models is based on studies which inherently assume that metabolized (i.e., filtered out of the blood by the kidneys) 210Po is plated with the same efficiency as tracer 210Po which has been added to urine samples. Urine samples collected after intravenous administration of 210Po citrate to two species of nonhuman primates were divided and simultaneously analyzed via two methods: the historical procedure of plating 210Po from raw urine for one sample and a method which includes the addition of 208Po tracer and sample digestion with concentrated HNO3 prior to 210Po deposition for the other sample. A more significant amount of 210Po was consistently recovered when the urine was wet ashed then when it was not wet ashed. A temporal relationship was found to describe the change in the ratio of the deposition recoveries for the two methods. Possible mechanisms for this phenomenon and its dosimetric implications are discussed.

Animals↗
PubMed1989

Six new isolates of human immunodeficiency virus type 2 (HIV-2) and the molecular characterization of one (HIV-2CAM2).

We report the isolation of human immunodeficiency virus type 2 (HIV-2) from each of six West Africans with AIDS-related complex or AIDS. One isolate (HIV-2CAM2) was molecularly cloned and shown by restriction mapping to differ in seven out of 22 sites from the prototype HIV-2ROD. Nevertheless, by a number of serological criteria these isolates are all clearly HIV-2.

AIDS-Related Complex↗
PubMed1988

The Karpas AIDS Cell Test compared with an enzyme-linked immunosorbent assay for detecting antibody to the human immunodeficiency viruses (HIV-I and HIV-2).

We have compared the Karpas AIDS Cell Test for antibodies to the human immunodeficiency viruses (HIV) with a commercial enzyme-linked immunosorbent assay (ELISA) (Organon Teknika) by testing serum samples from 324 intravenous drug abusers in Turin. The cell test was found to be more sensitive and as specific as the ELISA with the serum samples from the drug abusers. In Lisbon, 30 samples were tested on slides containing cells infected with HIV-1 and/or HIV-2. All 15 samples, which were positive for HIV-2 alone (in the HIV-2 Elavia test and by the Western blotting technique), were also positive in the Karpas AIDS test. In contrast, only one of the 15 samples (7%) gave a positive reading in the ELISA for HIV-1. Results of 30 samples tested in Turin and Lisbon by the Western blotting technique agreed closely with those obtained with the Karpas AIDS Cell Test. We were also able to show that the entire test can be performed at room temperature and completed within 1 hour. Moreover, the cell test requires minimal skill and simple equipment and is inexpensive. It also includes non-infected cells as a control and the specificity of positive samples may be verified with a bench microscope. Furthermore, this test which detects antibodies to both HIV-1 and HIV-2 allows rapid typing of the infecting strain.

Acquired Immunodeficiency Syndrome↗