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Biomedical subjects

S MacRae

Publications and source records attributed to S MacRae.

At least 19 recordsLinked to original sources
PubMed2005

Clinical bioethics integration, sustainability, and accountability: the Hub and Spokes Strategy.

The "lone" clinical bioethicist working in a large, multisite hospital faces considerable challenges. While attempting to build ethics capacity and sustain a demanding range of responsibilities, he or she must also achieve an acceptable level of integration, sustainability, and accountability within a complex organisational structure. In an effort to address such inherent demands and to create a platform towards better evaluation and effectiveness, the Clinical Ethics Group at the Joint Centre for Bioethics at the University of Toronto is implementing the Hub and Spokes Strategy at seven hospitals. The goal of the Hub and Spokes Strategy is to foster an ethical climate and strengthen ethics capacity broadly throughout healthcare settings as well as create models in clinical bioethics that are excellent and effective.

Bioethics↗
PubMed2002

Workers' understanding of chemical risks: electroplating case study.

BACKGROUND: There is limited research concerning how small companies in particular, respond to health and safety messages. AIMS: To understand individuals' knowledge and beliefs about chemical risks and to compare these with those of experts. METHODS: The use of chromic acid in particular, and also other chemicals associated with chrome plating were studied. All chromium plating firms were based in the West Midlands. The methodology involved initial face to face interviews (n = 21) with chromium platers, structured questionnaires (n = 84) to test the prevalence of beliefs identified in the interviews, an expert questionnaire, and a workshop to discuss findings. The responses of platers were compared with those of occupational health and safety experts. RESULTS: Although chromium platers appeared to understand the short term adverse effects of the chemicals to which they are exposed, their understanding of long term, or chronic effects appeared to be incomplete. They had good knowledge of acute effects based primarily on experience. Platers were aware of the hazardous nature of the chemicals with which they work, but did not draw distinction between the terms "hazards" and "risks". They had difficulties articulating the effects of the chemicals and how exposure might occur; although it is inappropriate to equate this with lack of knowledge. A significant minority of platers displayed deficiencies in understanding key technical terms used in Safety Data Sheets. CONCLUSIONS: This study provides a method which can be used to gain some understanding of workers' knowledge and beliefs about risks that they are exposed to in the workplace. The study also identifies gaps between the platers' knowledge and beliefs and those of experts. New risk information needs to be designed which addresses the information needs of platers using language that they understand.

Acute Disease↗
PubMed2001

Bitoric laser in situ keratomileusis for the correction of simple myopic and mixed astigmatism.

OBJECTIVE: To evaluate the safety and efficacy of bitoric laser in situ keratomileusis (LASIK) for the correction of simple myopic and mixed astigmatism. DESIGN: Retrospective, single-center, and noncomparative case series. PARTICIPANTS: Eighty-six eyes of 56 patients were analyzed for this study. Six-month and 1-year follow-up data were available on 86 eyes and 72 eyes, respectively. Eyes were divided in two groups according to the type of astigmatism: myopic astigmatism with low sphere (< -2 diopters) and mixed astigmatism. The range of astigmatism was 1.25 to 7.5 diopters. INTERVENTION: LASIK was performed using the Automated Corneal Shaper (ACS) microkeratome (Bausch & Lomb, Claremont, CA) to create a cornea flap using the 130- or 160-micron thickness plate. A bitoric mid-stromal ablation was performed using the Nidek EC-5000 excimer laser (Nidek Company, Gamagori, Japan). MAIN OUTCOME MEASURES: Uncorrected visual acuity, manifest refraction, and best spectacle-corrected visual acuity were the parameters measured preoperatively and at months 1, 3, 6, and 12. RESULTS: At the last visit, an uncorrected visual acuity of 20/20 or better was achieved in 77% and 68% of the myopic and mixed astigmatism groups, respectively. Ninety-two percent of all eyes had a mean spherical equivalent within +/- 0.50 diopter of emmetropia. A mean decrease in the vectorial magnitude of the astigmatism of 94% and 91% was achieved for those eyes with myopic and mixed astigmatism, respectively. There was no loss of best spectacle-corrected visual acuity. In two eyes, the axis of the positive cylinder was misaligned. CONCLUSION: Bitoric LASIK is an effective procedure to correct myopic and mixed astigmatism. Eighty-five percent of the eyes achieved an uncorrected visual acuity of 20/25 or better and had a final cylinder of 0.5 diopter or less. It is a safe operation, because no eyes lost any lines of best spectacle-corrected visual acuity. Longer follow-up may be needed to assess these results.

Adult↗
PubMed1999

Excimer ablation design and elliptical transition zones.

PURPOSE: To describe the rationale behind elliptical and other transition designs used with the excimer laser. SETTING: Casey Eye Institute, Oregon Health Sciences University, Portland, Oregon, USA. METHODS: Ablation zone designs were analyzed for the number of transition points for myopia and hyperopia. The advantages and disadvantages of elliptical transition zones are demonstrated graphically, with an emphasis on smooth ablation zone design to maximize the optics and biologic tolerance by the eye. RESULTS: The use of an individualized elliptical transition maximizes a circular effective optical zone and can enhance the smoothness of the transition zone while minimizing excessive tissue removal. CONCLUSION: Elliptical transition zones may improve the optics and biologic tolerance of excimer laser treatments.

Cornea↗
PubMed1999

Sterile interface keratitis associated with micropannus hemorrhage after laser in situ keratomileusis.

Numerous etiologies have been suspected to lead to sterile interface keratitis after laser in situ keratomileusis. This tan interface haze with a rippled appearance has been called Sands of the Sahara. We present 2 cases in which red blood cells entered the interface after a small hemorrhage from peripheral corneal vascularization during the microkeratome pass. Although this bleeding was controlled and all visible blood cells were removed at surgery, both patients developed the appearance of a focal interface keratitis on the first postoperative day.

Astigmatism↗
PubMed1999

The built environment as a component of quality care: understanding and including the patient's perspective.

BACKGROUND: Although there has been little systematic assessment of how the built environment of health care facilities affects the quality of care, the built environment is a major element of structure of care--one of three facets of quality. Yet in contrast to the growing trend of using consumer perceptions of both processes and outcomes of care in QI activities, quality assessments of the structure of care do not currently rely on patient feedback. PURPOSE OF PROJECT: During the initial phase of a multiphase project, nine focus groups were conducted in 1997 to identify the salient dimensions of experience from the patient's perspective. The content of these focus groups guided the development of assessment tools in the second phase of the project, which began in February 1998. FINDINGS: Participants in three focus groups that were held in each of three settings--ambulatory care, acute care, and long term care--described in detail a variety of reactions to the built environment. Analysis revealed eight consistent themes in what patients and family member consumers look for in the built environment of health care. In all three settings, they want an environment, for example, that facilitates a connection to staff and caregivers, is conducive to a sense of well-being, and facilitates a connection to the outside world. DISCUSSION: Data derived from the focus group research has guided the development of quantitative survey and assessment tools. For each setting, patient-centered checklists and questionnaires are designed to help institutions set priorities for the improvement of facility design from the patient's perspective.

Facility Design and Construction↗
PubMed1993

Agrobacterium rhizogenes-mediated transformation to improve rooting ability of eucalypts.

In an attempt to improve rooting in in vitro propagated Eucalyptus clones, root-inducing genes on the Ri plasmids of three Agrobacterium rhizogenes strains were inserted into the Eucalyptus genome. Root development was monitored in vitro and after the plantlets had hardened off. Only transformed roots grew as root cultures in hormone-free liquid medium. The potential use of this procedure for improving rooting of clonal material is discussed.

Journal Article↗
PubMed1991

Corneal ulcer and adverse reaction rates in premarket contact lens studies.

We analyzed clinical data on 22,739 contact lens wearers who were studied and whose lenses were approved under 48 manufacturer-sponsored studies for the Food and Drug Administration between 1980 and 1988. The incidence of corneal ulcers was low in the cosmetic (nontherapeutic) daily-wear soft and rigid gas-permeable lens wearers (1/1,923 and 1/1,471 patient-years, respectively). Corneal ulcers and severe adverse reactions occurred two to four times more frequently in extended-wear cosmetic soft and rigid gas-permeable lens wearers than in cosmetic daily-wear lens wearers. Aphakic extended-wear soft lens users were nine times more likely to develop a corneal ulcer when compared to the soft daily-wear cosmetic group. Corneal abrasions and keratitis accounted for 81 of 159 severe adverse reactions, whereas corneal ulcers accounted for 28 of 159 adverse reactions. The data indicate that overnight extended wear of contact lenses is associated with a greater risk of serious, sight-threatening complications than daily wear.

Aphakia↗
PubMed1989

Diurnal variation in vision after radial keratotomy.

We tested eight patients who had undergone radial keratotomy with regard to refraction, keratometry, corneal thickness, and intraocular pressure one to two weeks after surgery. Patients were examined immediately after eye-lid opening at 7:30 A.M. and again at 4:00 P.M. The contralateral eye was used as a control. The treated eye was 1.48 +/- 0.24 diopters (mean +/- S.E.M.) more hyperopic at the morning examination compared to the afternoon visit, whereas the control eye had an insignificant shift (0.16 +/- 0.06 diopters). The treated eye was significantly flatter (1.37 +/- 0.19 diopters) in the morning than in the afternoon when compared to the control eyes, which were only 0.11 +/- 0.09 diopter flatter. The intraocular pressure changed insignificantly in both the treated and control eyes (-0.5 +/- 0.53 mm Hg and -0.5 +/- 0.84 mm Hg, respectively). The mean morning corneal thickness was significantly greater (5.7%) than the afternoon thickness when compared to the controls (1.7% morning increase in thickness). These data suggest that diurnal variation in corneal thickness after radial keratotomy plays a role in diurnal variation of vision in the early postoperative period.

Adult↗
PubMed1989

Disinfection of Goldmann tonometers against human immunodeficiency virus type 1.

Goldmann tonometer tips were inoculated with 5 X 10(5) IU of cell-free or cell-associated human immunodeficiency virus type 1 (lymphadenopathy virus type 1 isolate) or 10(4) plaque-forming units of herpes simplex virus type 1 (McKrae strain) or type 2 (Hicks strain). In an effort to mimic a "worst case" clinical scenario, each respective virus was allowed to air dry on the tonometer tip for 10 minutes. Inoculated tonometers were then (1) not treated, (2) wiped with a disposable (Kim-wipe) tissue or sterile gauze; (3) wiped with sterile gauze soaked with 3% hydrogen peroxide; or (4) wiped with a 70% isopropyl alcohol swab. The hydrogen peroxide treatment and the alcohol wipes both completely disinfected the tonometer tips for human immunodeficiency virus type 1 and herpes simplex virus types 1 and 2, whereas wiping with a sterile gauze or tissue was not effective. Wiping the Goldmann tonometer tip with an isopropyl alcohol swab and then allowing the alcohol to evaporate provides a ready and efficient means of inactivating these three enveloped viruses.

1-Propanol↗
PubMed1987

Serologic markers after the transplantation of corneas from donors infected with human immunodeficiency virus.

Four corneas from two cadavers that later had positive test results on enzyme-linked immunosorbent assays and Western blot analysis for antibodies against the human immunodeficiency virus were inadvertently transplanted to recipients who were without known risk of human immunodeficiency virus infection. We performed serial studies of serologic markers of human immunodeficiency virus infection in the cornea recipients and assayed reverse transcriptase levels of their mixed lymphocyte cultures. The four cornea transplant recipients were followed up for 130, 152, 397, and 440 days, respectively, and the results on all serologic tests and reverse transcriptase assays remain negative.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Alterations in lymphocyte recognition repertoire during ageing. I. Analysis of changes in immune response potential of B lymphocytes from non-immunized aged mice, and the role of accessory cells in the expression of that potential.

The repertoire of specificities recognized by endogenous plaque-forming cells of young or aged mice has been examined, as well as the repertoire of specificities represented by mitogen-activated B cells of those animals. Significant changes occur in both polyclonal endogenous plaque-forming cells and polyclonal B cell responsiveness, as well as reactivity for antigens expressed on bromelain-treated mouse erythrocytes and mouse Ig-coupled sheep erythrocytes. Adoptive transfer experiments suggest that these changes reflect a role for the differentiative environment in the regulation of the B cell recognition repertoire. Additional analysis of changes in antigen-presenting cells in aged mice suggest that alterations in the manner of presentation of environmental antigens in vivo may control the expressed B cell repertoire. Indeed, under experimental conditions it has proven less easy to induce B cell/macrophage restriction (for antigen presentation and induction of antibody formation) in cells of old animals than in cells of younger mice.

Aging↗
PubMed1984

Recognition specificities, development and possible biological function of natural killer cells in the mouse. II. Changes in NK recognition during ontogeny and ageing, and examination of role of environment in controlling the expressed recognition repertoire.

We have used a spleen fragment assay to assess subpopulations of NK effector cells in individual mice and to analyse the patterns of inhibition of lytic activity seen in the presence of different sugars (mono-, di- and tri-saccharides). Our data suggest that during ontogeny the heterogeneity (diversity) of the NK effector population increases in a fashion which is somewhat characteristic of the individual strain under investigation. Furthermore, when a similar analysis was performed on NK cells in the spleen of lethally irradiated recipient mice receiving syngeneic or semi-allogeneic bone marrow stem cell precursors, we found that the phenotype of inhibition by different sugars was a characteristic of the bone marrow donor and not of the recipient. In so far as the assay described assesses target recognition by NK cells (and not subsequent parameters involved in the lytic event) these data can be interpreted in terms of a relative independence of the expressed recognition repertoire of NK cells from the environment in which their differentiation occurs.

Aging↗
PubMed1984

Altered lymphocyte recognition repertoire during ageing. III. Changes in MHC restriction patterns in parental T lymphocytes and diminution in T suppressor function.

Irradiated C57BL/6 and (C57BL/6 X C3H)F1 mice have been reconstituted with bone marrow prepared from young (2 month) or aged (24 month) C57BL/6 donors. Indirect examination of the T cell receptor for H-2d alloantigens on H-2b splenocytes of these reconstituted mice, using the suppression of the H-2b anti-H-2d response induced by (H-2b X H-2d)F1 anti-(H-2b anti-H-2d) suppressor cells, suggests that the allo-receptor repertoire derived from bone marrow of aged mice is different from that of T cells derived from young bone-marrow precursors. These observations were supported by direct evidence, from rosette formation with murine erythrocytes, for changes in the T cell receptor of these different (radiation-chimaera) sources of H-2b-T cells. Along with these subtle changes in the allo-receptor repertoire of T cells derived from bone marrow of aged mice grown in irradiated F1 hosts, there is a decrease (compared with mice reconstituted with bone marrow from young donors) in the apparent frequency of T cells recognizing antigen in association with the new MHC-restricting elements in these parent F1 chimaeras. Analysis of those cell subsets reported to be involved in the regulation of MLC responses suggests that some of the differences observed between T cell differentiation from bone-marrow stem cells of young or aged donors may in part be explained by a diminution in the production from bone marrow of aged mice of those cells important for homeostasis within the immune system.

Aging↗
PubMed1983

Alteration in lymphocyte recognition repertoire during aging. II. Changes in the expressed T-cell receptor repertoire in aged mice and the persistence of that change after transplantation to a new differentiative environment.

Changes in the T-lymphocyte alloreceptor repertoire associated with aging by exploring the frequency of cytotoxic T-lymphocyte precursors (CTLp) available for activation by various major histocompatibility complex (MHC) haplotypes in mice of different ages have been investigated. There was no consistent pattern of change in CTLp frequencies. Thus, for instance, while the frequency of responder C57B1/6 CTLp for ATH alloantigen decreased with age, the frequency for C3H alloantigen increased. There was no significant change in the overall frequency of splenic CTLp (assessed irrespective of antigen specificity). No evidence was found that CTL produced by activated CTLp of aged mice were less specific in their lytic capacity that CTL produced by CTLp of young mice. However, by assaying responder CTLp cultures at limiting dilution we obtained evidence that the "burst size" (mean lytic capacity per responder well assayed at limiting dilution) was diminished with age of the donor of the CTLp pool. Furthermore, we obtained evidence that the apparent affinity of CTL for their target antigen was consistently decreased when those effector cells were derived from a pool of CTLp of aged mice. All of these changes reflected in mature T cells derived from aged mice were already apparent in the bone marrow stem cell pool of aged individuals and were not due to environmental influences alone, as assessed by the phenotype of T cells derived from young or old bone marrow stem cells transplanted to young or aged recipient mice. A final study has examined evidence for more subtle changes in the T-cell alloreceptor repertoire, reflecting heterogeneity in young or aged mice in the recognition repertoire associated with a given antigenic specificity. By preparing F1 anti (parent anti-F1)-suppressor cells directed against CTL from young parental mice (a, b, c), or aged parental mice (x, y, z), we have explored the heterogeneity in the anti-C3H alloreceptor repertoire in individual young or aged C57B1/6 mice. Suppression by immunized F1 animals was assessed in tissue culture (inhibition of mixed lymphocyte culture (MLC) responses) or in vivo (inhibition of lethal GvHD induced by inoculation of parental lymphocytes into sublethally irradiated F1 hybrid mice). Irrespective of the assay system used, the data suggests that the receptor repertoire of aged T lymphocytes uses recognition structures different from those of young individuals, and that there is less individual-to-individual variation in the receptor repertoire of aged mice than in young mice.

Aging↗
PubMed1983

Recognition specificities, development, and possible biological function of natural killer cells in the mouse. I. Spleen focus forming assay for natural killer activity and analysis of lectin-like recognition structures on the surface of murine natural killer cells.

A number of simple sugars have been tested and found to be effective in blocking lysis of YAC-1 tumor target cells by nonimmune murine natural killer (NK) effector cells. Using a spleen fragment culture system an assay has been developed which allows us to compare the inhibition of lysis observed in replicate culture wells prepared from cells contained in one spleen fragment (less than or equal to 1 X 10(6) cells). The inhibition pattern of any well was found to fall naturally into 1 of 25 (of the total 128 possible tested) patterns. Using this panel analysis of NK activity in individual mice of the same or different strain has been compared. Our data suggest that within any given strain the inhibition pattern of NK effector cells is quite uniform. Consistent differences are seen between strains which are interpreted in terms of a genetic control of the final expression of the NK recognition repertoire. In adult F1 hybrid individuals the pattern of recognition by NK cells is best considered a result of the codominant expression of genes contributed by each parent.

Animals↗