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Biomedical subjects

T Hickey

Publications and source records attributed to T Hickey.

At least 19 recordsLinked to original sources
PubMed2002

In vivo evaluation of a dexamethasone/PLGA microsphere system designed to suppress the inflammatory tissue response to implantable medical devices.

The purpose of this research effort was to evaluate in vivo a newly developed dexamethasone/PLGA microsphere system designed to suppress the inflammatory tissue response to an implanted device, in this case a biosensor. The microspheres were prepared using an oil/water (O/W) emulsion technique. The microsphere system was composed of drug-loaded microspheres (including newly formulated and predegraded microspheres) and free dexamethasone. The combination of the drug and drug-loaded microspheres provided burst release of dexamethasone followed by continuous release from days 2-14. Continuous release to at least 30 days was achieved by mixing predegraded and newly formulated microspheres. The ability of our mixed microsphere system to control tissue reactions to an implant then was tested in vivo using cotton thread sutures to induce inflammation subcutaneously in Sprague-Dawley rats. Two different in vivo studies were performed, the first to find the dosage level of dexamethasone that effectively would suppress the acute inflammatory reaction and the second to show how effective the dexamethasone delivered by PLGA microspheres was in suppressing chronic inflammatory response to an implant. The first in vivo study showed that 0.1 to 0.8 mg of dexamethasone at the site minimized the acute inflammatory reaction. The second in vivo study showed that our mixed microsphere system suppressed the inflammatory response to an implanted suture for at least 1 month. This study has proven the viability of microsphere delivery of an anti-inflammatory to control the inflammatory reaction at an implant site.

Animals↗
PubMed2002

Dexamethasone/PLGA microspheres for continuous delivery of an anti-inflammatory drug for implantable medical devices.

The purpose of this research was to develop polylactic-co-glycolic acid (PLGA) microspheres for continuous delivery of dexamethasone for over a 1-month period, in an effort to suppress the acute and chronic inflammatory reactions to implants such as biosensors, which interfere with their functionality. The microspheres were prepared using an oil-in-water emulsion technique. The oil phase was composed of 9:1 dichloromethane to methanol with dissolved PLGA and dexamethasone. Some microspheres were predegraded for 1 or 2 weeks. Ten percent of polyethylene glycol was added to the oil phase in alternative formulations to delay drug release. The in vitro release studies were performed in a constant temperature (37 C) warm room, in phosphate-buffered saline at sink conditions. Drug loading and release rates were determined by HPLC-UV analysis. The standard microsphere systems did not provide the desired release profile since, following an initial burst release, a delay of 2 weeks occurred prior to continuous drug release. Predegraded microspheres started to release dexamethasone immediately but the rate of release decreased after only 2 weeks. A mixed standard and predegraded microsphere system was used to avoid this delay and to provide continuous release of dexamethasone for 1 month.

Anti-Inflammatory Agents↗
PubMed2002

The androgen receptor CAG repeat polymorphism and X-chromosome inactivation in Australian Caucasian women with infertility related to polycystic ovary syndrome.

The human androgen receptor (AR) gene contains a polymorphic trinucleotide (CAG) repeat sequence in exon 1. The number of CAG repeats may confer differential receptor activity, and specific ranges of variants have been correlated with androgen-sensitive disease processes. Polycystic ovary syndrome (PCOS) is a female condition characterized by androgen excess and infertility, many features of which are effected through the AR. We compared frequency distributions of CAG repeat alleles and their pattern of expression via X-inactivation analysis among 83 fertile women and 122 infertile women with PCOS, all of Australian Caucasian ethnicity. A population comparison with 831 predominantly fertile Australian women was also used. PCR-based assays were used to genotype each woman and assess allele inactivation patterns after digestion of DNA with methylation-sensitive HpaII. Infertile women with PCOS exhibited a greater frequency of CAG alleles or biallelic means greater than 22 repeats compared with both the fertile control group (P < 0.05) and the general population (P < 0.01). Preferential expression of longer CAG repeat alleles was also observed in PCOS and correlated with increased serum T. We conclude that the AR (CAG)n gene locus and/or its differential methylation patterns influence the disease process leading to PCOS.

Adult↗
PubMed2001

Cognitive impairment and functional status in elderly institutionalized patients with schizophrenia.

OBJECTIVE: The relationship of cognitive impairment to functional status in older adults with schizophrenia was investigated. PATIENTS: Ninety-three psychiatric inpatients with schizophrenia between the ages of 65 and 88 years. Two subsets of this sample, consisting of 48 and 24 patients, were studied with a greater number of assessment instruments. MEASURES: The Mini-Mental State Examination (MMSE) was used for brief assessment of overall cognitive functioning, and the Psychogeriatric Dependency Rating Scale (PGDRS) was administered to assess functional status. The cognitive test battery from the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) and/or an expanded neuropsychological battery, was given to a subset of the patients. RESULTS: In the overall sample, patients with greater global cognitive impairment had higher levels of rated impairment on the individual items that comprised the Orientation and Physical, but not Behavior, subscales of the PGDRS. Furthermore, in the two subsamples, specific neuropsychological measures of problem-solving, word list learning, naming and constructional praxis were related to overall measures of outcome. CONCLUSIONS: Neuropsychological deficit and psychosocial outcome are multi-dimensional entities that relate to one another in complex ways.

Activities of Daily Living↗
PubMed2001

Characterization and biocompatibility studies of novel humic acids based films as membrane material for an implantable glucose sensor.

Multilayered films of humic acids (HAs) (naturally occurring biopolymers) were investigated as a potential semipermeable membrane for implantable glucose sensors. These films were grown using a layer-by-layer self-assembly process of HAs and oppositely charged ferric ions. The growth of these assemblies exhibited strong dependence on the pH and ionic strength of HAs solutions, which correlated with the degree of ionization of the carboxyl groups and neutralization-induced surface spreading. Quartz crystal microbalance (QCM) and ellipsometric studies have shown repeatable, stepwise increase in mass (as high as 5.63 microg/cm(2)) and in film thickness (ca. 24.3 nm per layer) for these assemblies. The permeability of glucose through these membranes can be regulated by varying the number of self-assembled HAs/Fe(3+) layers. Moreover, a 200 nm thick HAs/Fe(3+) film (in its hydrated state) had a shear modulus of about 80 MPa, implying stability upon implantation. These films were determined to be biocompatible since in vivo studies indicated only mild tissue reaction along with some neovascularization.

Animals↗
PubMed2000

Effect of adults' self-regulation of diabetes on quality-of-life outcomes.

OBJECTIVE: To examine the relationships among cognitive representations of diabetes, diabetes-specific health behaviors, and quality of life using Leventhal and Diefenbach's self-regulation model of illness (Leventhal H, Diefenbach M: The active side of illness cognition. In Mental Representation in Health and Illness. SkeltonJA, Croyle RT, Eds. New York, Springer-Verlag, 1991, p. 247-272). RESEARCH DESIGN AND METHODS: This research involved secondary analysis of a mailed survey completed by 296 adults (ages 20-90 years). Structural equation modeling was conducted to investigate relationships among cognitive representations, diabetes-specific health behaviors, and quality of life. Model differences by diabetes type were also investigated. RESULTS: Findings indicated that certain cognitive representation constructs were related to increased diabetes-specific health behaviors, decreased sense of burden, and positive quality-of-life outcomes. Individuals levels of understanding of diabetes and their perceptions of control over diabetes were the most significant predictors of outcomes. However, diabetes-specific health behaviors were related to an increased sense of burden that was negatively associated with quality of life. Multigroup analyses indicated that this self-regulatory model provided a good fit for individuals with type 1 diabetes, those with type 2 diabetes who take insulin, and those with type 2 diabetes who do not take insulin. CONCLUSIONS: These findings advance what is known about cognitive representations of illness and the self-regulation of diabetes as well as the relationships between cognitive representations of illness, quality of life, and behavioral factors. In particular, results from this study suggest the need for further study to address ways of reducing the burden of diabetes associated with health behaviors and decreased quality of life.

Adult↗
PubMed1999

Enteropathogens and other factors associated with severe disease in children with acute watery diarrhea in Lima, Peru.

To evaluate enteropathogens and other factors associated with severe disease in children with diarrhea, 381 children <5 years of age with diarrhea and moderate to severe dehydration (in-patients) and 381 age-, sex-, and date-of-visit-matched children with mild diarrhea (out-patients) presenting to a hospital in Peru, were studied. Rotavirus was detected in 52% of the in-patients and 35% of the out-patients (odds ratio [OR]=2.3, 95% confidence interval [95% CI]= 1.6-3.2); 95% of the rotaviruses among in-patients were of serotypes G1-G4. The risk of severe diarrhea was particularly great in children who were not exclusively breast-fed in early infancy and who also lacked piped water in their homes (for children with both characteristics OR=6.8, 95% CI=3.6-12.8). The high prevalence of rotavirus and its association with severe diarrhea underscores the need for rotavirus vaccines. Interventions to educate mothers and improve access to safe water should augment the impact of rotavirus vaccines in preventing severe diarrhea.

Animals↗
PubMed1997

Effects of a one-year physical activity intervention for older adults at congregate nutrition sites.

The effects of a physical activity intervention on strength, balance, motor coordination, and mobility were tested in a quasi-experiment at rural congregate nutrition sites. Twice-weekly sessions of low intensity movements were conducted for one year. Logistic regression results showed significant differences between intervention (n = 61) and comparison (n = 49) groups on several performance-based measures. Intervention subjects perceived significantly greater improvements in physical functioning over the previous year than did comparison subjects. A qualitative evaluation revealed perceived program benefits of pain reduction, increased flexibility, muscle strengthening, increased walking speed, and improved mental outlook.

Aged↗
PubMed1997

The pattern of change in leisure activity behavior among older adults with arthritis.

This study employed a "ceasing participation" framework to examine changing leisure activity patterns. Respondents of the Living With Arthritis project were classified into four participation pattern categories. Results confirmed that older adults with arthritis are more likely to experience changes to their activity regimen than older adults without arthritis. A multi-group discriminant function analysis showed that arthritis severity distinguished those who tend to cease activity. Social network and age best distinguished those who quit activities without replacement. Results are placed in the context of coping strategies. Those who do not replace forfeited activities with other activities are least flexible in their response to their chronic condition and face challenges to their well-being.

Aged↗
PubMed1996

Exercise participation in a frail elderly population.

A low-intensity exercise demonstration project was developed jointly by researchers, social service practitioners, and program participants to actively involve frail older people in their own health maintenance. This article describes this collaborative process and its impact on the success of the health promotion program, which was conducted at three senior centers serving a low-income, urban elderly population. Participants were predominantly sedentary women over age 70 with multiple chronic conditions. The program was conducted with peer leaders to facilitate its continuation after the research demonstration phase. In addition to positive health outcomes related to functional mobility, blood pressure maintenance, and overall well-being, this intervention was successful in sustaining active participation in regular physical activity through the use of peer leaders selected by the program participants. The planning, implementation, and outcomes of this project illustrate the benefits and challenges of combining research and practice perspectives in conducting health promotion interventions with older populations.

Black or African American↗
PubMed1995

Activity participation and well-being among older people with arthritis.

This study tests the hypotheses that (a) severity of arthritis is inversely associated with frequency of activity participation, and (b) arthritis sufferers who maintain higher levels of participation, particularly in activities which are social in nature, are less likely to experience a decline in well-being. Three activity types are considered: social, physical, and solitary. Results indicate that well-being is influenced by social activity, whereas solitary and physical activity have minimal impact. This suggests that elders with arthritis need not remove themselves from the pursuit of activity and should be encouraged to develop new interests when physical functioning fails. The study also demonstrates the utility of considering activity as multidimensional.

Aged↗
PubMed1994

Adaptation of a general optimism scale for use with older women.

The Life Orientation Test has been widely used with various populations since its development, but its psychometric properties among older adults have not been assessed. This study employed exploratory factor analysis to examine the factor structure of a modified version of the test for 90 frail older women. The results do not support a unidimensional conceptualization of optimism. Internal consistency reliability was lower for the entire scale than for separate factors representing positively versus negatively framed questions. Some support for construct validity was shown by small to moderate correlations with several related constructs. The results were likely to have been affected both by the modification of the test to simplify data collection with an elderly population and by a differing manifestation of the construct among functionally impaired older adults as compared to previous research with younger, healthier samples.

Aged↗
PubMed1993

Identifying formulas in first language acquisition.

With the increase in interest in formulas, or apparently non-productive utterances in children's speech, a range of definitions has emerged and sometimes conflicting criteria have been proposed for their identification. These definitions of formulas are compared, and the criteria of Brown (1973), Wong Fillmore (1976), Peters (1983) and Plunkett (1990) for the recognition of formulas are reviewed. A preference rule system is proposed, which distinguishes necessary, typical and graded conditions for the recognition of formulas. Using these conditions, some of the formulas found in the data of one child acquiring Irish between 1;4 and 2;1 are examined. Issues such as length of units, frequency of occurrence and appropriateness of use are discussed. The methods developed in this study could be used to assess the importance of formulas in the language acquisition of other children.

Child↗
PubMed1992

Mortality and the attribution of health problems to aging among older adults.

This study examined the association between mortality and attributing health problems to aging among 1391 respondents from the Longitudinal Study of Aging who indicated difficulty with activities of daily living. Of this number, 72 persons attributed impairment primarily to "old age." Logistic regression controlling for demographics, physical health problems, self-rated health, and social involvements showed an association with mortality (adjusted odds ratio = 1.78, CI = 1.05, 3.00). Attributing health problems to aging may carry a risk of adverse health events.

Activities of Daily Living↗
PubMed1992

The continuity of gerontological themes.

Based on the premise that scientists should periodically examine the history of their ideas and methodologies, this article focuses on the issue of continuity in the evolution of scientific knowledge about aging. Taking a twenty-five-year perspective, selected research questions and priorities in the biomedical, behavioral, and social domains of aging are used to exemplify the continuity of the gerontological knowledge base. This article concludes that there is considerable evidence of continuity, despite the strong influences of changing cohorts of people and external forces that have shaped new ideas and research questions in gerontology.

Aging↗
PubMed1991

Mean length of utterance and the acquisition of Irish.

One of the most widely used indices of language development is a measure of utterance length in morphemes (MLUm). This study examines the applicability of MLUm to the acquisition of Irish. MLUm was calculated for data from Cian, aged 1; 11-3; 0. Even when an attempt was made to 'assume the maximum' by counting all possible morphemes, the correlation between a morpheme MLU (MLUm) and a word count MLU (MLUw) was very high (0.99). This points to MLUw being as effective a measure of Irish development as MLUm, as well as being easier to apply and more reliable. MLUw was calculated for the two younger children in the study (Eibhlís 1; 4-2; 1 and Eoin 1; 10-2; 6). An examination of the relationship between the three children's MLUw values and their grammatical complexity as measured on ILARSP (the Irish adaptation of LARSP) indicates that MLUw is a useful preliminary index for early development in Irish. However, further data are necessary to check whether MLUw loses its predictive relationship with grammatical complexity after a certain point. The study emphasizes the caution necessary in applying MLU to languages whose acquisition has not hitherto been studied, and underlines the role of MLU as a preliminary measure, which must not be overinterpreted.

Age Factors↗