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Biomedical subjects

A Gillis

Publications and source records attributed to A Gillis.

At least 19 recordsLinked to original sources
PubMed2006

The use of megavoltage cone-beam CT to complement CT for target definition in pelvic radiotherapy in the presence of hip replacement.

In Europe and the USA combined, over half a million people had a hip joint replaced in 2005, contributing to the increasing number of radiotherapy patients with metallic hip prostheses. The treatment plan for external beam radiation therapy is based on the delineation of the anatomy in the planning CT scan. When implanted objects of high atomic number (Z) material are present, however, severe image artefacts are generated in conventional CT, strongly hindering the ability to delineate some organs. This is particularly the case for the planning of prostate patients with hip prostheses. This short communication presents the use of a new imaging modality, megavoltage cone-beam CT, to complement the regular CT for target definition of prostate cancer treatment of patients with hip replacements.

Hip Prosthesis↗
PubMed2006

ERK activity facilitates activation of the S-phase DNA damage checkpoint by modulating ATR function.

Although Erk kinase has been recently reported to function in the DNA damage response, the mechanism governing this process is unknown. We report here that hydroxyurea (HU) activates Erk via MEK1, a process that is sensitized by a constitutively active MEK1 (MEK1Q56P) and attenuated by a dominant-negative MEK1 (MEK1K97M). While ectopic MEK1Q56P sensitized HU-induced S-phase arrest, inhibition of Erk activation via U0126, PD98059, and MEK1K97M attenuated the arrest, and thereby enhanced cells to HU-induced toxicity. Taken together, we demonstrate an important contribution of Erk to the activation of the S-phase DNA damage checkpoint. This can be attributed to Erk's regulatory role in modulating ATR function. Inhibition of Erk activation with U0126/PD98059 and MEK1K97M substantially reduced HU-induced ATR nuclear foci, leading to a dramatic reduction of gammaH2AX and its nuclear foci. Reduction of MEK1 function by a small interference RNA (siRNA) MEK1 and ectopic MEK1K97M significantly decreased HU-induced gammaH2AX. Conversely, ectopic MEK1Q56P enhanced gammaH2AX foci. Furthermore, immunofluorescent and cell fractioning experiments revealed cytosolic and nuclear localization of ATR. HU treatment caused the redistribution of ATR from the cytosol to the nucleus, a process that is inhibited by U0126. Collectively, we show that Erk kinase modulates HU-initiated DNA damage response by regulating ATR function.

3T3 Cells↗
PubMed2006

Safe trabeculectomy technique: long term outcome.

AIM: To assess the long term outcome of a new trabeculectomy technique. METHODS: Trabeculectomy was performed using a fornix based conjunctival flap, an anterior chamber maintainer, a standardised punch technique, and a combination of adjustable and releasable sutures in 56 eyes of 53 patients. The main outcome measures were the postoperative intraocular pressure (IOP) and the frequency of early postoperative complications. The mean follow up time was 15.7 (range 12-21) months. RESULTS: The mean preoperative and postoperative IOP at 12 months were 21.2 (SD 6) and 12.8 (3.0) mm Hg, respectively. All patients had an IOP of <21 mm Hg, 90.9% had an IOP <18 mm Hg, and 61.4% had an IOP <14 mm Hg. Postoperative complications were infrequent: flat anterior chamber (1.8%), bleb leakage (0%), or hypotony (1.5%) beyond 3 weeks, or choroidal detachment at any time point (8.9%). CONCLUSIONS: This novel trabeculectomy method offers the possibility to tailor the IOP postoperatively with a minimum of postoperative complications and excellent IOP control at the long term follow up.

Adult↗
PubMed2005

Needling-revision of failed filtering blebs.

PURPOSE: To investigate the efficacy and safety of needling-revision of failed blebs after trabeculectomy. METHODS: A retrospective chart review of 28 eyes of 28 patients who underwent a trabeculectomy with subsequent needling-revision between January 2002 and December 2003. The mean follow-up was 15 months after the first needling-revision. All interventions were conducted by the same surgeon. Absolute success was defined as an IOP <18 mmHg without medication or as an IOP reduction > 20% without medication if the preoperative IOP was < or = 21 mmHg. Relative success was defined as meeting these criteria with or without medication. RESULTS: The mean interval between trabeculectomy and the first needling-revision was 5 months. Repeated needling-revision (up to 3 times) was performed as clinically necessary. In 90% of the needling-revisions 5-FU was used to prevent postoperative fibrosis. The mean +/- SD IOP before needling-revision and at the last follow-up was respectively 24.7 +/- 6 and 15.7 +/- 3 mmHg (p<0.001) Needling-revision was an absolute success in 39% (11/28) and a relative success in 68% (19/28). Minor complications attributed to needling-revision occurred in 32% including self reabsorbing subconjunctival bleeding (1), filamental (1) and punctate keratitis (1), transient choroidal effusion (3), wound leak (4) and hyphaema (2). Progression of cataract occurred in 1 patient. A serious complication occurred in 1 case (hypotony with persistent macular oedema). CONCLUSIONS: Bleb needling-revision can prevent more invasive intervention in a significant number of patients with failed trabeculectomy blebs. Complications are similar to those seen after trabeculectomy.

Adult↗
PubMed2004

Comparison of optical coherence reflectometry and ultrasound central corneal pachymetry.

In 50 eyes of 25 patients we prospectively measured the central corneal thickness (CCT) comparing the OLCR (Optical Low Coherence Reflectometry) pachymeter with the contact ultrasound pachymeter. The OLCR system was mounted on to a Haag-Streit slit lamp. Every single measurement was the result of 5 scans. With the contact ultrasound Sonomed pachymeter we performed 5 separate measurements and calculated the mean. The correlation between the two measurements was excellent (r = 0.99). The mean standard deviation (SD) of the measurements taken with the non-contact OLCR pachymeter was significantly lower than with the contact ultrasound pachymeter, 0.49 microm and 4.71 microm respectively (p < 0.01). The variability of the CCT measurements taken with the non-contact OLCR pachymeter is significantly lower than the variability of the CCT measurements taken with the contact ultrasound pachymetry.

Cornea↗
PubMed2001

Magnetic resonance imaging of relative glycosaminoglycan distribution in patients with autologous chondrocyte transplants.

RATIONALE AND OBJECTIVES: Autologous chondrocyte transplantation (ACT) is a potential treatment for full-thickness chondral lesions in the knee. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) has recently been developed as a sensitive and specific measure of cartilage glycosaminoglycans (GAGs). Under the conditions of dGEMRIC, T1 is directly related to the GAG concentration. Our aim for this study was to demonstrate the potential of dGEMRIC to evaluate ACT implants. METHODS: Eleven ACT implants were studied 2 to 24 months postoperatively by dGEMRIC. T1 values from three regions of interest were obtained to examine GAG content (1) in the implant, (2) in native cartilage adjacent to the implant, and (3) in native cartilage further removed from the implant (as "control"). RESULTS: One implant failed and therefore was not included. Four of the implants were studied between 2 and 6 months postoperatively and showed low T1 (GAG), less than 80% of the control native cartilage. Five of the six implants studied between 12 and 24 months postoperativley showed T1 (GAG) comparable to (>80%) of control. One 18-month graft showed low T1 comparable to the surrounding native cartilage, with normal GAG seen in cartilage far from the graft site. The GAG index (T1 values of the graft normalized to control) from the group of implants 6 months or less was 59% +/- 5% of control, whereas those at 12 to 24 months were 91% +/- 18% of control. The two groups were statistically different with a P value of 0.005. CONCLUSIONS: The GAG level in grafts that were implanted for less than 12 months appeared to be lower than that in the remote cartilage. At 12 months or greater, the grafts in this study had GAG levels that were comparable to both the adjacent and remote cartilage. This preliminary study of ACT implants has shown that it is feasible to apply the dGEMRIC technique in patients with ACT as a way to obtain information related to the composition of grafts. These results provide motivation and the pilot data with which to design further clinical studies.

Cartilage, Articular↗
PubMed2001

The management of patients who have suffered an acute myocardial infarction in a tertiary care centre.

BACKGROUND: The standard of management after acute myocardial infarction (MI) includes beta-blockers and acetylsalicylic acid (ASA). Angiotensin-converting enzyme (ACE) inhibitors and lipid-lowering agents are indicated for some patients, and calcium channel blockers should generally be avoided. It is suspected that many patients with MI are not discharged from hospital with optimal medical management. OBJECTIVES: To determine what proportion of patients in a tertiary care hospital with acute MI are discharged on optimal medical therapy, and to identify what barriers exist to obtaining optimal treatment for as many patients as possible. PATIENTS AND METHODS: Charts were retrospectively reviewed for 717 patients with acute MI admitted to the Queen Elizabeth II Health Sciences Centre, Halifax, Nova Scotia from January 1, 1997 to April 30, 1999. Charts were reviewed for demographics, comorbidities, investigations performed, and medications on admission and discharge. When discharge medications did not match the optimal medical management, the chart was reviewed for the reasoning behind the decisions. RESULTS: In-hospital mortality was 9.6%. Among 648 patients who survived to discharge, 577 (89.0%) were discharged on a beta-blocker, 261 (40.3%) on an ACE inhibitor, 105 (16.2%) on a calcium channel blocker and 578 (89.2%) on ASA. Patients 65 years of age or older were less likely than their younger counterparts to be discharged on a beta-blocker (272 of 315 [86.3%] versus 305 of 333 [91.6%], P<0.04) and more likely to be discharged on a calcium channel blocker (70 of 315 [22.2%] versus 35 of 333 [10.5%], P<0.0001). No significant difference in the use of beta-blockers or calcium channel blockers was found between men and women (beta-blockers: 385 of 432 [89.1%] men versus 192 of 216 [89.9%] women, P<0.92); calcium channel blockers (67 of 432 men [15.5%] versus 38 of 216 women [17.6%], P<0.50). Among patients with low density lipoprotein greater than 3.5 mmol/L, 158 of 200 (79.0%) were discharged on a lipid-lowering agent. Among patients with documented ejection fraction less than 40%, 94 of 103 (91.3%) were discharged on an ACE inhibitor. Most patients had acceptable contraindications to the medications that they did not receive. CONCLUSIONS: The study centre showed much better use of appropriate medications than has been previously described, showing that optimal medical therapy can be achieved for the vast majority of patients with acute MI.

Adrenergic beta-Antagonists↗
PubMed2000

Some potential errors in the measurement of mercury gas exchange at the soil surface using a dynamic flux chamber.

A series of controlled environment experiments were conducted to examine the use of a dynamic flux chamber to measure soil emission and absorption of total gaseous mercury (TGM). Uncertainty about the appropriate airflow rates through the chamber and chamber exposure to ambient wind are shown to be major sources of potential error. Soil surface mercury flux measurements over a range of chamber airflow rates showed a positive linear relationship between flux rates and airflow rate through the chamber. Mercury flux measurements using the chamber in an environmental wind tunnel showed that exposure of the system to ambient winds decreased the measured flux rates by 40% at a wind speed of 1.0 m s(-1) and 90% at a wind speed of 2 m s(-1). Wind tunnel measurements also showed that the chamber footprint was limited to the area of soil inside the chamber and there is little uncertainty of the footprint size in dry soil.

Air Pollutants↗
PubMed1998

Competencies of liberal education in post-RN baccalaureate students: a longitudinal study.

The purpose of this longitudinal study was to examine the relationship among liberal education competencies as demonstrated in the professional and personal lives of post-RN students and time spent in a BScN program. The six competencies identified by Dressel (1979) and used by Bottoms (1988) to define the liberally educated person provided the framework for this study. The Dressel competencies have been validated in the literature as being representative of the universe of competencies that are anticipated outcomes of baccalaureate nursing education. Results indicated that after 5 years of part-time study at the baccalaureate level, significant differences were found in the competencies of liberal education as demonstrated in the professional and personal lives of post-RN learners. The competencies as demonstrated in the professional lives of post-RN learners developed consistently over time, while the development of competencies as demonstrated in the personal lives of learners lagged behind. The study contributes to the small but growing body of literature which explores the impact of a liberal education on post-RN learners.

Canada↗
PubMed1996

Smoking among disadvantaged women: causes and cessation.

This study aimed to identify social-psychological factors associated with smoking and smoking cessation among disadvantaged women. Individual and group interviews were conducted with disadvantaged women in Atlantic Canada. Participants were predominantly poor, unemployed, geographically isolated, and single parents. The factors associated with smoking included coping with stresses, loneliness, powerlessness, low self-efficacy, social pressures, and addiction. Support from peers (i.e., women in similar circumstances) and partners was considered important. Health professionals and traditional cessation programs were not perceived as supportive. Participants viewed women's centres and women's agencies as appropriate deliverers of cessation programs. Methodological issues are discussed.

Adaptation, Psychological↗
PubMed1996

Teens for healthy living.

Improving the health and quality of life of adolescents is a fundamental aspiration of community health nurses. But developing health promotion programs that are attractive to young people can be a major challenge. In a rural Nova Scotia school district, this challenge has been met by bringing the teens themselves into the design and implementation of the program.

Adolescent↗
PubMed1994

Detection and differentiation of microbial siderophores by isoelectric focusing and chrome azurol S overlay.

Siderophores are microbial, low molecular weight iron-chelating compounds. Fluorescent Pseudomonads produce different, strain-specific fluorescent siderophores (pyoverdines) as well as non-fluorescent siderophores in response to low iron conditions. We present an isoelectric focusing method applicable to unpurified as well as to purified pyoverdine samples where the fluorescent siderophores are visualized under UV illumination. Siderophores from different Pseudomonas sp., amongst which are P. aeruginosa, P. fluorescens and P. putida, including egg yolk, rhizospheric and clinical isolates as well as some derived Tn5 mutants were separated by this technique. Different patterns could be observed for strains known to produce different siderophores. The application of the chrome azurol S assay as a gel overlay further allows immediate detection of non-fluorescent siderophores or possibly degradation products with residual siderophore activity. The method was also applied to other microbial siderophores such as deferrioxamine B.

Culture Media↗
PubMed1991

Oncogene rearrangements in chronic B-cell leukemia.

Forty-four B-chronic lymphocytic leukemias (CLL) were studied by Southern blot analysis using probes for the Ig genes and bcl-1, bcl-2 (major, minor and 5' breakpoint region), bcl-3, c-myc, and retinoblastoma (Rb) loci. Eight cases had three or more rearranged JH bands, indicating oligoclonality, clonal evolution, or chromosomal translocation. One case had a rearrangement of the bcl-1 locus and three of the bcl-2 locus. In the first case, comigration of the rearranged bcl-1 and JH sequences indicated a t(11;14)(q13;q32) translocation, which, in contrast to previously described cases, seems to be completely reciprocal. One case with a bcl-2 rearrangement showed comigration of the bcl-2 major breakpoint region and a rearranged JH band. This indicates a t(14;18) (q32;q21). The two other cases showed rearrangements of the bcl-2 5' breakpoint region without apparent comigration. No rearrangements were detected of c-myc and bcl-3, located at chromosome 19, nor was a deletion of Rb found. All but three cases had CD5 expression. The exceptions included the t(11;14) and the t(14;18) cases. Our results confirm recent data on rearrangements at the 5' site of bcl-2 in CLL. Additionally, they corroborate the presumption that CD5-negative chronic B-cell leukemias should be considered apart from classical CLL.

Antigens, CD↗
PubMed1991

The relationships between physical activity and health-promoting behaviours in mid-life women.

The purpose of this study is to examine the inter-relationships among participation between physical activity, perceived well-being, self-esteem, health status, health locus of control and health-promoting lifestyle activities of middle-aged women in a rural context. Since women comprise the largest (living) segment of the older population, it is extremely important to study the predictors of health promoting activities in this age group prior to old age. Recent research has noted that participation in physical activity acts as an entry point to reflect on health behaviour practices, creating a ripple effect to other areas of lifestyle behaviours. The research questions were framed within the Health Promotion Model. The study utilized a longitudinal experimental design. The findings of this study contribute to the small, but growing, research base on physical activity as a health-promoting lifestyle behaviour and physical activity as a lifestyle practice of women in the mid-life years. Findings also provide a base for the development of community physical-activity programmes and other intervention strategies to enhance the health and well-being of women, particularly those residing in a rural setting.

Adult↗