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Biomedical subjects

S Head

Publications and source records attributed to S Head.

At least 19 recordsLinked to original sources
PubMed2004

British HIV Association (BHIVA)/British Association for Sexual Health and HIV (BASHH) guidelines on provision of adherence support to individuals receiving antiretroviral therapy (2003).

The widespread use of highly active antiretroviral therapy (HAART) has dramatically reduced HIV-associated morbidity and mortality where treatment has been made available. Very high levels of adherence to HAART are a prerequisite for a successful virological and immunological response. Low adherence increases the risk of treatment failure and disease progression. It is also likely to lead to further transmission of resistant viruses, and to have a negative impact on the cost effectiveness of HAART. Low adherence is difficult to predict, and this has two key implications for service provision. Firstly, HAART should not be withheld on the basis of assumptions about adherence. Secondly, support with adherence should be provided to all patients prescribed HAART. Our understanding of barriers to and enablers of high adherence, and the evidence base regarding effective interventions, is limited. Meta-analysis of randomized controlled trials available from the general literature suggests multiple interventions are required to maintain high adherence to chronic therapy. This document recommends a series of measures for adoption within HIV clinical care settings, based on evaluation of existing data. High adherence is a process, not a single event, and therefore adherence support must be integrated into clinical follow up. Every prescribing unit should have a written policy on provision of adherence support, and ensure that staff are appropriately trained to make delivery of such services possible.

Anti-HIV Agents↗
PubMed2002

Defining signal thresholds in DNA microarrays: exemplary application for invasive cancer.

BACKGROUND: Genome-wide or application-targeted microarrays containing a subset of genes of interest have become widely used as a research tool with the prospect of diagnostic application. Intrinsic variability of microarray measurements poses a major problem in defining signal thresholds for absent/present or differentially expressed genes. Most strategies have used fold-change threshold values, but variability at low signal intensities may invalidate this approach and it does not provide information about false-positives and false negatives. RESULTS: We introduce a method to filter false-positives and false-negatives from DNA microarray experiments. This is achieved by evaluating a set of positive and negative controls by receiver operating characteristic (ROC) analysis. As an advantage of this approach, users may define thresholds on the basis of sensitivity and specificity considerations. The area under the ROC curve allows quality control of microarray hybridizations. This method has been applied to custom made microarrays developed for the analysis of invasive melanoma derived tumor cells. It demonstrated that ROC analysis yields a threshold with reduced missclassified genes in microarray experiments. CONCLUSIONS: Provided that a set of appropriate positive and negative controls is included on the microarray, ROC analysis obviates the inherent problem of arbitrarily selecting threshold levels in microarray experiments. The proposed method is applicable to both custom made and commercially available DNA microarrays and will help to improve the reliability of predictions from DNA microarray experiments.

Journal Article↗
PubMed2001

Binge eating disorder and night eating syndrome: psychological and behavioral characteristics.

OBJECTIVE: The present study was designed to examine the psychological and behavioral characteristics associated with both night eating syndrome (NES) and binge eating disorder (BED) in 42 males and 41 females who were enrolled in a university-based weight loss center. METHOD: Individuals were classified into one of four groups: NES only (N = 23), BED only (N = 13), both NES and BED (N = 13), or no diagnoses of an eating disorder (N = 34). Analyses of covariance (covarying for age and gender) were conducted to compare patients with BED and NES. RESULTS: NES patients scored lower on disinhibition than BED patients (p <.01). Also, individuals who met criteria for both disorders scored higher than NES only patients on state anxiety (p <.01), disinhibition (p =.08), and trait anxiety (p =.08). DISCUSSION: These results suggest that NES represents a subcategory among the obese, which also overlaps with binge eaters. In addition, anxiety distinguished individuals who met criteria for both disorders from patients who were diagnosed with either NES or BED.

Adolescent↗
PubMed2001

Histomorphometric analysis of the normal adult patella.

The patellae of 6 male and 2 female, 40 to 70 year-old individuals, who were healthy at the time of their violent death, were assessed by computer-assisted image analysis. The means of the bone density (percentage of bone in the respective field of interest) ranged from approximately 20% to approximately 30% in the central spongiotic zones, from approximately 40% to approximately 80% in the superior and inferior peripheral zones, and approximately 40% to approximately 60% in the subchondral zone. Bone densities were greatest in the lateral parts of the subchondral and spongiotic territories. The bony trabeculae were haphazardly distributed in the central spongiotic zones. They were commonly oriented vertically or parallel to the surface of the patella in the peripheral and subchondral zones. In conclusion, the histomorphometric data presented validate the rationale of reaming the articular aspect of the patella into a dome-shaped configuration with preservation of a circumferential bony bulwark in the preparation for the implantation of a thick polyethylene-based component with a concave undersurface.

Adult↗
PubMed2000

The biomechamcal and surgical solutions for patella implant in total knee arthroplasty.

A basic fault in designs of patella implants that calls for a prompt remedy is the inadequate polyethylene thickness in contact areas. The requirement for thickness of patella implants should be similar to the requirement set up by the FDA in 1993 regarding the tibial implants, that is, a minimal thickness of 8 mm. A solution is presented for the optimal design of the patella implant and for the appropriate surgical technique. The implant's undersurface that fixes to bone is concave and has a 1-cm wide but 5 to 6 mm short central peg that does not risk the integrity of the bone. Fixation of the concave aspect to the convex aspect of the bony patella strongly enhances resistance to medio-lateral and supero-inferior shear forces. The circumferential facet of the implant 8 mm thick assures uniform thickness of the entire implant and assures optimal mechanical properties of the polyethylene. The articulating surface is tailored to conform to the corresponding femoral trochlear groove and condyles. It can be made to fit any femoral component of any knee implant.

Arthroplasty, Replacement, Knee↗
PubMed1997

Construct validity of the Impact of Weight on Quality of Life Questionnaire.

The Impact of Weight on Quality of Life questionnaire (IWQOL) is a 74-item self-report, condition-specific instrument that (1) assesses the effect of weight on quality of life in eight key areas, and (2) may be used as a treatment outcome measure and/or an evaluation tool for healthcare policy makers and third-party payers. This study explores IWQOL construct validity and provides new information on internal consistency, treatment effects, and differences between men and women. IWQOL total scores correlated highly with other measures of overall quality of life, and subscale scores correlated well with counterparts in the assessment battery. Internal consistency estimates for the IWQOL scales generally were high. For the women, 4-week participants, and the total sample, pretreatment-posttreatment differences were significant for all IWQOL scales and total score. For men, treatment differences were significant for the total score and all subscales except for Work and Mobility. Treatment differences for 2-week participants were significant for all scales except for Work. Consistent with previous IWQOL study results, the Comfort With Food scale scores reflected more discomfort at posttreatment as compared with pretreatment. The IWQOL, already translated into French and Italian, currently is demonstrating clinical and research utility as a quality-of-life outcome measure for clinical trials of antiobesity drugs and surgical treatments for patients with obesity.

Activities of Daily Living↗
PubMed1995

Assessing Impact of Weight on Quality of Life.

This paper is a preliminary report on the development of a new instrument, the Impact of Weight on Quality of Life (IWQOL) questionnaire, that assesses the effects of weight on various areas of life. We conducted two studies utilizing subjects in treatment for obesity at Duke University Diet and Fitness Center. The first study describes item development, assesses reliability, and compares pre- and post-treatment scores on the IWQOL. In the second study we examined the effects of body mass index (BMI), gender, and age on subjects' perceptions of impact of weight on quality of life. Results indicate adequate psychometric properties with test-retest reliabilities averaging .75 for single items, and .89 for scales. Scale internal consistency averaged .87. Post-treatment scores differed significantly from pre-treatment scores on all scales, indicating that treatment produced positive changes in impact of weight on quality of life. The results of the second study indicate that the impact of weight generally worsened as the patients' size increased. However for women there was no association between BMI and impact of weight on Self-Esteem and Sexual Life. Even at the lowest BMI tertile studied, women reported that weight had a substantial impact in these areas. There were also significant gender differences, with women showing greater impact of weight on Self-Esteem and Sexual Life compared with men. The impact of age was a bit surprising, with some areas showing positive changes and others showing no change.

Adult↗
PubMed1993

Tying pay to performance: one critical care unit's approach.

This article describes development and testing of a tool for determining an appropriate reward for staff performance in a critical care area. Outlined is the process of identifying and quantifying appropriate merit increases based on bedside performance as well as participation in other unit, hospital, professional and community activities. Positive results are reported after one- and two-year use.

Career Mobility↗
PubMed1991

Time series analysis of obsessional behavior and mood during self-imposed delay and response prevention.

Time series analysis of more than a year of daily self-report of three subjects showed that self-imposed delay and response prevention was effective in decreasing obsessions and compulsions. The subject-controlled treatment had a varied effect on mood-anxiety decreased in two subjects, but depression increased in one. (A similar worsening of mood after elimination of obsessional behavior was found in a previous case study.) Apparently, successful treatment of obsessional behavior will not necessarily lead to an improvement in mood. Concurrent mood symptoms need to be targeted separately; and, plans should be made to deal with mood symptoms that may occur once obsessional behavior is removed.

Adolescent↗
PubMed1990

Modification of the glycolipid-binding specificity of vero cytotoxin by polymyxin B and other cyclic amphipathic peptides.

Polymyxin B, an amphipathic cyclic decapeptide produced by Bacillus polymyxa, is routinely used in the extraction of the components from the periplasmic space of gram-negative bacteria. Vero cytotoxin 1 (VT1) is an Escherichia coli-elaborated subunit toxin which binds to the glycolipid globotriosylceramide (Gal-alpha 1-4-Gal beta 1-4-Glc-ceramide [Gb3]) and has been strongly implicated in the etiology of the hemolytic uremic syndrome and hemorrhagic colitis. We now show by in vitro glycolipid-binding assays that in the presence of low concentrations of polymyxin B, globotetraosylceramide (GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc-ceramide [Gb4]) is also recognized by both the VT1 B (binding) subunit and holotoxin. Melittin, a 26-amino-acid cyclic peptide of similar amphipathic nature, produced the same effect, whereas a hydrophobic blocking agent did not. Triton X-100 did not increase binding of VT1 to Gb4 but prevented glycolipid binding in toto at concentrations above 0.5%. Caution is therefore advised in the analysis of VT1 glycolipid binding in the presence of amphipathic peptides.

Bacterial Toxins↗
PubMed1989

Interaction of concanavalin A and a divalent derivative with lymphocytes and reconstituted lymphocyte membrane glycoproteins.

Both concanavalin A (con A) and its divalent derivative, succinyl-concanavalin A (S-con A) are mitogenic for porcine lymph node lymphocytes. We have compared the binding of these two lectins to intact porcine lymphocytes and phospholipid vesicles containing reconstituted lymphocyte membrane glycoproteins. Both con A and S-con A showed high- and low-affinity binding to intact cells, as indicated by LIGAND analysis of Scatchard plots of binding data. Despite the apparently identical saccharide specificities of the two lectins, high-affinity binding sites for S-con A were only one-third as numerous as high-affinity sites for the parent lectin. Large numbers of low-affinity binding sites existed for con A, while many fewer were present for S-con A. It is suggested that these sites result from hydrophobic association. Con A bound to lymphocytes in a positively cooperative fashion, while S-con A showed noncooperative behavior. Lectin binding to large unilamellar phospholipid vesicles containing reconstituted lymphocyte membrane glycoproteins was measured using a rapid filtration assay, and was linear with the glycoprotein content of the vesicles. Almost all of the outward-facing glycoprotein was functional in terms of lectin binding. Reconstituted glycoproteins showed only a single class of high-affinity binding sites for both con A and S-con A, with association constants similar to those measured for intact cells. Con A, but not S-con A, showed positively cooperative binding to reconstituted vesicles. Cooperativity was observed in both gel phase and liquid crystalline phase lipid, and was thus not dependent on long-range lateral rearrangement of glycoprotein receptors. Results suggested that con A induces a microredistribution of receptors on the lymphocyte membrane surface, leading to the exposure of glycoproteins that were previously inaccessible to the lectin. S-Con A does not cause glycoprotein redistribution, and a large fraction of the receptors remain cryptic.

Animals↗