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J Crook

Publications and source records attributed to J Crook.

At least 19 recordsLinked to original sources
PubMed2001

Systematic overview of the evidence for brachytherapy in clinically localized prostate cancer.

BACKGROUND: Brachytherapy (permanent implantation of radioactive seeds) has emerged as an alternative to existing standard therapy with radical prostatectomy or external beam radiotherapy in the treatment of clinically localized (T1 and T2) prostate cancer. The Genitourinary Cancer Disease Site Group of the Cancer Care Ontario Practice Guidelines Initiative examined the role of brachytherapy in treating clinically localized prostate cancer. METHODS: A systematic review of articles published from 1988 to April 1999, retrieved through a search of MEDLINE and CANCERLIT databases, was combined with a consensus interpretation of the evidence in the context of conventional practice. RESULTS: Although there were no randomized trials comparing brachytherapy with standard treatment, evidence was available from 13 case series and 3 cohort studies. Rates of freedom from biochemical failure (biochemically no evidence of disease [bNED]) varied considerably from one series to another and were highly dependent on tumour stage, grade and pretreatment serum prostate-specific antigen (PSA) levels. Results in patients with favourable tumours (T1 or T2 tumour, Gleason score of 6 or lower, serum PSA level of 10 ng/mL [microgram/L] or less) were comparable to those in patients undergoing radical prostatectomy. Acute urinary retention was reported in 1%-14% of patients. Long-term sequelae occurred in less than 5% of patients and included urinary incontinence, cystitis, urethral strictures and proctitis. Sexual potency was maintained after implantation in 86%-96% of patients. INTERPRETATION: At present, there is insufficient evidence to recommend the use of brachytherapy over current standard therapy for localized prostate cancer. Brachytherapy using transrectal ultrasound guidance for seed implantation is promising in terms of freedom from biochemical failure in selected patients with early-stage prostate cancer. Brachytherapy is currently available outside of clinical trials, but whenever possible patients should be asked to participate in randomized trials comparing brachytherapy and current standard therapy. Brachytherapy should be available to selected patients (those with T1c or T2a tumours, a Gleason score of 6 or lower and a serum PSA level of 10 micrograms/L or less), after discussion of the available data and potential adverse effects.

Brachytherapy↗
PubMed2001

The effect of seed orientation deviations on the quality of 125I prostate implants.

We quantified the effect of seed orientation deviations on five prostate seed implant cases at our institution. While keeping their positions fixed, the iodine-125 seeds were assigned orientations sampled from a realistic probability distribution derived from the post-implant radiographs of ten patients. Dose distributions were calculated with both a model that explicitly includes anisotropy (TG43 anisotropy function) and a point source model (TG43 anisotropy factor). Orientation deviations had only a small influence on prostate dose-volume histograms: the 95% confidence intervals on the volumes receiving 100%, 150% and 200% dose were at most +/-0.8%, +/-1.1% and +/-0.6% of the prostate volume, respectively. The dose-volume histograms of anisotropic seed distributions were marginally better than those with isotropic point-source seeds. Anisotropy caused a displacement of cold spots (regions receiving <100% of the prescribed dose) in <1% of the prostate volume. Our results indicate no net benefit to prostate dosimetry in using more isotropic seeds. Furthermore, we propose a new 'weighted anisotropy function' to better account for the effects of anisotropy when seed orientation is unknown. Conceptually, the TG43 anisotropy factor described in AAPM TG43 averages the effect of anisotropy over all solid angles, with the implicit assumption that all seed orientations are equally probable. In prostate implants, however, seeds are preferentially oriented parallel to the needle axis. The proposed weighted anisotropy function incorporates this non-uniform probability.

Anisotropy↗
PubMed2001

Climbing the ladder: a step by step approach to international guidelines for water recycling.

Given the pressures on the world's freshwater resources, recycled water is a valuable resource. Recycled water can increase the reliability of water supply because it is an independent source of water. Water recycling requires effective measures to protect public health and the environment. In the absence of comprehensive international guidelines, different countries have developed different approaches to managing water recycling depending on the understanding of the health risks, their individual economic circumstances, and affordability. Approaches vary between high technology/high cost/low risk and low technology/low cost/controlled risk. Furthermore, differences occur between countries and within individual countries. Inconsistencies can often be traced to lack of a unified scientific position on health effects. These inconsistencies increase public concerns about health risks and may give rise to conservative controls on responses to water recycling projects that some countries may be unable to afford. In this paper, an international panel of authors discusses how the different water recycling approaches might be linked together into international water recycling guidelines. These guidelines would incorporate a uniform approach to assessing hazards and risks while providing flexibility for individual countries to vary requirements to suit local circumstances of affordability and risk. The authors propose a framework of guidelines in which individual countries can progressively improve recycled water quality as lower risk levels become more affordable. The authors argue that a uniform international approach will result in a number of benefits including a better focus on risk management, better targeted research and development efforts and greater public confidence in water recycling. The authors invite discussion on the concepts put forward in the paper.

Animals↗
PubMed2000

A prospective comparison of three systems of patient immobilization for prostate radiotherapy.

PURPOSE: The study compared the setup reliability of 3 patient immobilization systems, a rubber leg cushion, the alpha cradle, and the thermoplastic Hipfix device, in 77 patients with cT1-T3, N0, M0 prostate cancer receiving conformal radiotherapy. METHODS AND MATERIALS: Port films were analyzed and compared to simulation films to estimate the setup errors in the three coordinate axes (anterior-posterior, cranial-caudal, medial-lateral). A total vector error was calculated from these shifts. RESULTS: The Hipfix was found significantly superior to the other two devices in reducing mean setup errors in all axes (p < 0.005). The average field-positioning error with the Hipfix ranged from 1.9 mm to 2.6 mm for all axes, whereas the deviation for the other two systems ranged from 2.7 to 3. 4 mm. Errors greater than 10 mm were virtually eliminated with the Hipfix system. There was a reduction in the mean total vector error in the alpha cradle and Hipfix patient cohorts over time, reflecting improved efficacy as a result of experience. CONCLUSION: There was a significant difference in the performance of each immobilization device. The Hipfix was consistently more reliable in reducing setup errors than the other devices.

Analysis of Variance↗
PubMed2000

Postradiotherapy prostate biopsies: what do they really mean? Results for 498 patients.

PURPOSE: Postradiotherapy (RT) prostate biopsies are prone to problems in interpretation. False negatives due to sampling error, false positives due to delayed tumor regression, and indeterminate biopsies showing radiation effect in residual tumor of uncertain viability are common occurrences. METHODS AND MATERIALS: A cohort of 498 men treated with conventional RT from 06/87-10/96 were followed prospectively with systematic transrectal ultrasound (TRUS)-guided post-RT prostate biopsies, starting 12-18 months after RT. If there was residual tumor but further decline in serum prostate-specific antigen (PSA), biopsies were repeated every 6-12 months. Patients with negative biopsies were rebiopsied at 36 months. Residual tumor was evaluated for RT effect and proliferation markers. The 498 men had 978 biopsies. Median time of the first biopsy (n = 498) was 13 months, biopsy #2 (n = 342) 28 months, biopsy #3 (n = 110) 36 months, biopsy #4 (n = 28) 44 months, and biopsy #5 (n = 4) 55 months. Median follow-up is 54 months (range 13-131). One hundred seventy-five patients (34%) had prior hormonal therapy for a median of 5 months (range 1-60). RESULTS: Clinical stage distribution was T1b: 46; T1c: 50; T2a: 115; T2b/c: 170; T3: 108; T4: 11; Tx: 1. Distribution by Gleason score was: 28% Gleason score 2-4; 42%: 5-6; 18%: 7; and 12%: 8-10. Seventy-one men have died, 26 of prostate cancer and 45 of other causes. Actuarial failure-free survival by T stage at 5 years is T1b: 78%; T1c: 76%; T2a: 60%; T2b/c: 55%; T3: 30%; and T4: 0%. Actuarial freedom from local failure at 5 years is T1b: 83%; T1c: 88%; T2a: 72%; T2b/c: 66%; T3: 58%; and T4: 0%. The proportion of indeterminate biopsies decreases with time, being 33% for biopsy 1, 24% for biopsy 2, 18% for biopsy 3, and 7% for biopsy 4. Thirty percent of indeterminate biopsies resolved to NED status, regardless of the degree of RT effect, 18% progressed to local failure, and 34% remained as biopsy failures with indeterminate status within the time frame of this report. Positive staining for proliferation markers was associated with both subsequent local failure and also any type of failure. In multivariate analysis, only PSA nadir (p = 0.0002) and biopsy status at 24-36 months (p = 0. 0005) were independent predictors of outcome. CONCLUSIONS: Post-RT prostate biopsies are not a gold standard of treatment efficacy, but are an independent predictor of outcome. Positive immunohistochemical staining for markers of cellular proliferation is associated with subsequent local failure. Indeterminate biopsies, even when showing marked RT effect, cannot be considered negative.

Adult↗
PubMed2000

Effects of urethrography on prostate position: considerations for radiotherapy treatment planning of prostate carcinoma.

PURPOSE: Retrograde urethrography is commonly used to define the prostate apex at simulation. This study evaluated the hypothesis that urethrography causes prostate displacement, resulting in an error in treatment planning. METHODS AND MATERIALS: Forty-five patients with carcinoma of the prostate were evaluated. Gold seeds were placed in the apex, posterior wall, and base of the gland. In the first 20 patients, the position of the seed-defined apex was compared at simulation (with urethrogram) and on day 1 of treatment (without urethrogram). In the second cohort of 25 patients, the effects of urethrography on prostate position were evaluated directly at simulation by comparing the position of apex pre- and post-urethrography. An analysis was performed to estimate the possible impact of urethrogram-induced prostate motion on target coverage. RESULTS: The mean superior displacement in the first and second cohort was 5.2 mm and 6.8 mm, respectively (combined mean shift 6.1 mm). With a 10-mm field margin below the tip of the urethrogram cone, 56% of patients in this study would have inadequate planning target volume (PTV) coverage. CONCLUSION: Retrograde urethrography causes a significant superior shift of the prostate. Strict reliance on urethrography in determining the inferior field margin could result in inadequate treatment.

Adenocarcinoma↗
PubMed2000

Biological markers and schizophrenia.

OBJECTIVE: The delivery of biological markers for schizophrenia would greatly assist preventative strategies by identifying at-risk individuals who could then be monitored and treated in a manner with a view to minimising subsequent morbidity. This paper aims to present a selection of biological measures that may indicate risk of schizophrenia. METHOD: A selective and brief review is provided of intensively studied putative markers, including enlarged cerebral ventricles, dopamine D2 receptor density, amphetamine-stimulated central nervous system dopamine release, plasma homovanillic acid and smooth pursuit eye tracking dysfunction. RESULTS: A number of biological measures have been reported to be correlated with schizophrenia. CONCLUSIONS: Presently, none of these measures has satisfactory performance characteristics in terms of predictive validity, noninvasiveness, ease of testing and low cost that would enable their widespread use. However, a few have potential for further investigation and development.

Biomarkers↗
PubMed2000

Artemis: sequence visualization and annotation.

SUMMARY: Artemis is a DNA sequence visualization and annotation tool that allows the results of any analysis or sets of analyses to be viewed in the context of the sequence and its six-frame translation. Artemis is especially useful in analysing the compact genomes of bacteria, archaea and lower eukaryotes, and will cope with sequences of any size from small genes to whole genomes. It is implemented in Java, and can be run on any suitable platform. Sequences and annotation can be read and written directly in EMBL, GenBank and GFF format. AVAILABITLTY: Artemis is available under the GNU General Public License from http://www.sanger.ac.uk/Software/Artemis

Databases, Factual↗
PubMed2000

Confirmation of psaA in all 90 serotypes of Streptococcus pneumoniae by PCR and potential of this assay for identification and diagnosis.

The gene encoding the pneumococcal surface adhesin A (PsaA) protein, psaA, was confirmed in all Streptococcus pneumoniae serotypes by a newly developed PCR (psaA PCR) assay. Eighty-nine of the 90 serotypes amplified produced an 838-bp fragment; the exception was a serotype 16F strain acquired from the American Type Culture Collection (ATCC). Analysis of 20 additional 16F strains from the United States and Brazil showed that the gene was amplified in all 16F strains, implying that the serotype 16F ATCC strain must be a variant. The specificity of the assay was verified by the lack of signal from analysis of heterologous bacterial species (n = 30) and genera (n = 14), including viridans group streptococci. The potential of the assay for clinical application was shown by its ability to detect pneumococci in culture-positive nasopharyngeal specimens. Demonstration of psaA in all 90 serotypes and lack of amplification of heterologous organisms suggest that this assay could be a useful tool for detection of pneumococci and diagnosis of disease.

Adhesins, Bacterial↗
PubMed2000

National Research Council report on potable reuse.

In 1998, the United States National Research Council prepared a report assessing the viability of potable reuse. The report concludes that planned indirect potable reuse is a viable application of reclaimed water but should be considered for implementation only after other alternative measures, such as development of new water sources, nonpotable reuse, and water conservation, have been evaluated and determined not to be economically or technically feasible. Although health-effects research has not indicated that there have been any adverse health effects resulting from drinking highly treated reclaimed water, those data are sparse. There are uncertainties associated with assessing the potential health risks of drinking reclaimed water. The report acknowledges that several issues remain unresolved regarding reclaimed water treatment and reliability, microbial and chemical constituents of concern, and water quality and health effects monitoring. Research needs include methods to detect emerging pathogens, identification and quantification of trace organic compounds, development of suitable in vivo toxicological methods, and evaluation of the effectiveness and reliability of multiple treatment barriers. The report also concludes that direct potable reuse is not a viable option to consider at this time.

Conservation of Natural Resources↗
PubMed1999

The importance of hemoglobin levels during radiotherapy for carcinoma of the cervix.

BACKGROUND: It is unclear whether blood transfusion can overcome the negative impact of anemia before or during radiotherapy (RT) in patients with carcinoma of the cervix. The objective of this retrospective study was to examine the impact of anemia and blood transfusion on 605 patients with carcinoma of the cervix treated with radical RT at 7 centers across Canada in 1989, 1990, and 1992. METHODS: The data collected included hemoglobin (Hgb) levels from the time of diagnosis to the end of therapy; blood transfusions administered; and identifiable patient-, tumor-, and treatment-related factors. Survival, disease free survival, and pelvic control analyses were evaluated by univariate and multivariate analysis. RESULTS: The median follow-up was 41 months (range, 0-92 months). Presenting Hgb level, average weekly nadir Hgb (AWNH) during RT, and blood transfusion were correlated significantly with local control, disease free survival, and overall survival on univariate analysis. However, the AWNH remained significant on multivariate analysis, whereas Hgb at presentation and blood transfusion did not. The 5-year survival was 74% for patients with an AWNH >/= 120 g/L, 52% for patients with AWNH levels 110-119 g/L inclusive, and 45% for patients with AWNH levels < 110 g/L (P < 0.0001). At each Hgb level, patients who were transfused and maintained a specific Hgb level had a survival rate that was not significantly different from patients who were at that level spontaneously. There was a significant reduction in both pelvic and distant recurrence (P < 0.0001 and P < 0.0006, respectively) in patients whose AWNH level during RT was >/= 120 g/L compared with < 120 g/L. A reduction in the rate of distant recurrence was observed in patients with and without pelvic recurrence. CONCLUSIONS: AWNH is highly predictive of outcome for patients treated with RT for carcinoma of the cervix. Blood transfusion appears to overcome the negative prognostic effects of low presenting Hgb levels and AWNH levels.

Adenocarcinoma↗
PubMed1999

Regional soft tissue pains: alias myofascial pain?

This chapter deals with four main questions: what is the evidence that 'myofascial pain' syndromes exist?; what is the evidence that the myofascial pain concept is clinically useful?; what is the evidence that managing patients in terms of the myofascial pain diagnosis confers benefits?; and what is the evidence-based management of myofascial pain? The purpose of a diagnosis is to provide boundaries around subgroups of illness in a population since each subgroup presumably has a different mechanism, natural history, prognosis, course and response to treatment. The current literature is divided in its conceptual approach to the problem of regional musculoskeletal pain. Some authors regard myofascial pain as being distinct from regional musculoskeletal pain while others regard these as synonymous. A postulated theory of the pathophysiology of myofascial pain is discussed. This contrasts with a view that regional myofascial pain represents a non-specific localized pain arising from multiple regional, systemic and psychosocial factors. In order to consider myofascial pain as a distinct diagnosis, it would be necessary to resolve reliability issues in the identification of its critical diagnostic features. Beyond reliability issues, there are also problems of sensitivity and specificity--i.e. of the patient population that it identifies--which must be resolved if controlled trials are to be conducted. The clinical usefulness of the myofascial pain diagnosis is considered with regard to what is believed about the course of healing, the determinants of disability, the course of regional versus widespread musculoskeletal pain, the relationship of musculoskeletal injury to pain, and the evidence-based management of musculoskeletal pain. An epidemiological perspective is proposed with regard to regional musculoskeletal pain. This allows for the identification of operationally defined strata of regional musculoskeletal pain and permits studies in course, prognosis and treatment, even though some conceptual issues such as the 'myofascial pain diagnosis' remain to be clarified.

Fibromyalgia↗
PubMed1999

Accuracy of polyp detection by gastroenterologists and nurse endoscopists during flexible sigmoidoscopy: a randomized trial.

BACKGROUND & AIMS: The use of nurse endoscopists to perform flexible sigmoidoscopy is expanding, increasing the availability of colorectal cancer screening. However, the effectiveness of this practice has not been studied in randomized trials. The aim of this trial was to examine the miss rate of polyps, the depth of sigmoidoscope insertion, and the incidence of complications during flexible sigmoidoscopy performed by nurse endoscopists and by gastroenterologists. METHODS: Three hundred twenty-eight patients were randomized to undergo screening flexible sigmoidoscopy performed by a nurse endoscopist or by a gastroenterologist. Frequency of missed polyps was determined by repeat sigmoidoscopy, performed by a gastroenterologist blinded to the identity of the first endoscopist. Multiple logistic regression analysis identified characteristics associated with missed polyps. RESULTS: Gastroenterologists and nurse endoscopists had equivalent miss rates for adenomatous polyps (20% vs. 21%, respectively; P = 0.91). No complications occurred in any patient. Gastroenterologists inserted the sigmoidoscope further than nurse endoscopists (61 vs. 55 cm, respectively; P < 0.00001). Polyp location in the descending colon (odds ratio, 4.1; 95% confidence interval, 1.7-10.3) was highly associated with missed polyps. CONCLUSIONS: No differences in detection of adenomatous polyps or frequency of complications were found. These data suggest that experienced nurse endoscopists may perform screening flexible sigmoidoscopy as safely and as effectively as gastroenterologists.

Adult↗
PubMed1999

Regional soft tissue pains: alias myofascial pain?

This chapter deals with four main questions: what is the evidence that 'myofascial pain' syndromes exist?; what is the evidence that the myofascial pain concept is clinically useful?; what is the evidence that managing patients in terms of the myofascial pain diagnosis confers benefits?; and what is the evidence-based management of myofascial pain? The purpose of a diagnosis is to provide boundaries around subgroups of illness in a population since each subgroup presumably has a different mechanism, natural history, prognosis, course and response to treatment. The current literature is divided in its conceptual approach to the problem of regional musculoskeletal pain. Some authors regard myofascial pain as being distinct from regional musculoskeletal pain while others regard these as synonymous. A postulated theory of the pathophysiology of myofascial pain is discussed. This contrasts with a view that regional myofascial pain represents a non-specific localized pain arising from multiple regional, systemic and psychosocial factors. In order to consider myofascial pain as a distinct diagnosis, it would be necessary to resolve reliability issues in the identification of its critical diagnostic features. Beyond reliability issues, there are also problems of sensitivity and specificity--i.e. of the patient population that it identifies--which must be resolved if controlled trials are to be conducted. The clinical usefulness of the myofascial pain diagnosis is considered with regard to what is believed about the course of healing, the determinants of disability, the course of regional versus widespread musculoskeletal pain, the relationship of musculoskeletal injury to pain, and the evidence-based management of musculoskeletal pain. An epidemiological perspective is proposed with regard to regional musculoskeletal pain. This allows for the identification of operationally defined strata of regional musculoskeletal pain and permits studies in course, prognosis and treatment, even though some conceptual issues such as the 'myofascial pain diagnosis' remain to be clarified.

Journal Article↗
PubMed1998

Elderly recipients of home nursing services: pain, disability and functional competence.

Despite increasing evidence that pain is a problem with which many in their later years must contend, little is known about the experience of community-dwelling seniors who require the assistance of home nursing services to remain independent and functional in their homes. This study investigated the prevalence and experience of pain among seniors who were recipients of home nursing services. The study was guided by the World Health Organization Classification of Impairment, Disability and Handicap. Face to face interviews were conducted with 66 individuals who reported whether they were often troubled by pain and/or had experienced pain of a noteworthy nature within the 2 weeks prior to the interview. In addition, they responded to standardized questions about their pain experience and their levels of disability and functional competence. Findings revealed that although three-quarters of respondents reported pain, there was no association between pain and measures of disability. Findings, however, revealed an association between pain and measures of functional competence, more specifically, global function, level of depressive symptomatology, sleep impairment and satisfaction with life. Implications for nursing include the need for a heightened awareness of the prevalence of pain in community-dwelling older adults and the development of assessment and intervention strategies that support their quality of life.

Activities of Daily Living↗
PubMed1998

Immunoreactivity of five monoclonal antibodies against the 37-kilodalton common cell wall protein (PsaA) of Streptococcus pneumoniae.

Five monoclonal antibodies (MAbs) were produced against the Streptococcus pneumoniae pneumococcal surface adhesin A (PsaA) 37-kDa common cell wall protein. These antibodies were used in a dot immunoblot and Western blot study of clinical isolates of S. pneumoniae to detect the presence of the protein. By both assays, the MAbs reacted with clinical isolates representing the 23 type-specific serotypes present in the licensed pneumococcal polysaccharide vaccine. Western blot analysis confirmed the presence of a protein migrating in the gel with a molecular mass of 37 kDa. An extension of the study by using dot immunoblot analysis that included an analysis of the 90 serotypes of S. pneumoniae showed that all five MAbs reacted with 89 of the 90 serotypes tested. MAb 1B6, the exception, did not react with S. pneumoniae serotype 16F. Dot immunoblot analysis of the MAbs with Enterococcus faecalis and viridans streptococci showed varied reactivity patterns, depending on the species. The MAbs against the 37-kDa antigen did not react with Escherichia coli, respiratory pathogens, or nonpathogens representing 22 genera and 29 species of bacteria. All five MAbs also reacted with five multidrug-resistant strains of S. pneumoniae. In summary, these MAbs may be useful for detection of pneumococcal antigen and may lead to the development of diagnostic assays for pneumococcal disease.

Adhesins, Bacterial↗
PubMed1998

Capturing tumour stage in a cancer information database.

OBJECTIVE: 1. To present the steps taken and lessons learned from one cancer centre's efforts to capture tumour stage information in a cancer database. 2. To determine the accuracy of the stage data through a chart audit. 3. To describe the potential uses of stage information in a cancer centre. DESIGN AND SETTING: This is a retrospective review of an initiative to capture tumour stage information at a regional cancer centre in Ontario. DATA SOURCES: The minutes of the centre's Health Records and Medical Advisory Committees related to staging were reviewed. Data on stage by tumour type was extracted from the centre's Oncology Patient Information System (OPIS). Three hundred and ninety charts were analysed to assess the accuracy of stage information and identify staging errors. Health Information Services workload statistics were reviewed to determine the types and frequency of projects undertaken using stage-related data. RESULTS: In January 1994, the Ottawa Regional Cancer Centre introduced policies and procedures to capture stage-related information. Standardized staging forms and a physician reminder system encouraged the centre's physicians to record tumour stage within 3 months of new patient registration. Of all qualifying cases in 1994, 92% were staged. A medical audit in 1998 of 390 charts from the 3 previous years of staging data revealed that 71.5% of the charts reviewed had been staged completely. Of the incompletely staged cases, 19% to 57% had TNM recorded, but the stage grouping was not recorded, or the "stage" was the extent of disease at the time of disease progression rather than at initial diagnosis (35% to 71%). Physician-related staging errors occurred in 2% to 5% of cases; data-entry errors occurred in 3% to 6% of cases. CONCLUSIONS: Stage information has enabled the centre to better describe its patient clientele for accreditation purposes and to assist researchers in estimating the number of patients potentially available for prospective and retrospective studies. It is being used to guide targeted educational initiatives to selected populations in the region's catchment area and assists administrators in estimating resource needs. Resistance to the capture of stage information can be overcome with persistence, the development of procedures that facilitate physician compliance, including a reminder system, the development of institutional policies and procedures and by feedback on the uses and availability of stage information.

Accreditation↗