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J Hanson

Publications and source records attributed to J Hanson.

At least 19 recordsLinked to original sources
PubMed2006

Observation of muon neutrino disappearance with the MINOS detectors in the NuMI neutrino beam.

This Letter reports results from the MINOS experiment based on its initial exposure to neutrinos from the Fermilab NuMI beam. The rates and energy spectra of charged current nu(mu) interactions are compared in two detectors located along the beam axis at distances of 1 and 735 km. With 1.27 x 10(20) 120 GeV protons incident on the NuMI target, 215 events with energies below 30 GeV are observed at the Far Detector, compared to an expectation of 336+/-14 events. The data are consistent with nu(mu) disappearance via oscillations with |Delta(m)2/32|=2.74 +0.44/-0.26 x10(-3)eV(2) and sin(2)(2theta(23))>0.87 (68% C.L.).

Journal Article↗
PubMed2006

Declines in HIV prevalence can be associated with changing sexual behaviour in Uganda, urban Kenya, Zimbabwe, and urban Haiti.

OBJECTIVE: To determine whether observed changes in HIV prevalence in countries with generalised HIV epidemics are associated with changes in sexual risk behaviour. METHODS: A mathematical model was developed to explore the relation between prevalence recorded at antenatal clinics (ANCs) and the pattern of incidence of infection throughout the population. To create a null model a range of assumptions about sexual behaviour, natural history of infection, and sampling biases in ANC populations were explored to determine which factors maximised declines in prevalence in the absence of behaviour change. Modelled prevalence, where possible based on locally collected behavioural data, was compared with the observed prevalence data in urban Haiti, urban Kenya, urban Cote d'Ivoire, Malawi, Zimbabwe, Rwanda, Uganda, and urban Ethiopia. RESULTS: Recent downturns in prevalence observed in urban Kenya, Zimbabwe, and urban Haiti, like Uganda before them, could only be replicated in the model through reductions in risk associated with changes in behaviour. In contrast, prevalence trends in urban Cote d'Ivoire, Malawi, urban Ethiopia, and Rwanda show no signs of changed sexual behaviour. CONCLUSIONS: Changes in patterns of HIV prevalence in urban Kenya, Zimbabwe, and urban Haiti are quite recent and caution is required because of doubts over the accuracy and representativeness of these estimates. Nonetheless, the observed changes are consistent with behaviour change and not the natural course of the HIV epidemic.

Adolescent↗
PubMed2006

Current trends in Rwanda's HIV/AIDS epidemic.

OBJECTIVE: To review the trajectory of Rwanda's HIV epidemic, including long term trends and more recent trends in HIV prevalence, markers of HIV incidence, and behavioural indicators. METHODS: This paper reviews the history of HIV serological and behavioural surveillance efforts in Rwanda, dating back to the early 1980s, synthesising findings from surveillance, research, and other relevant HIV programmatic data. The documentation reviewed includes published findings, conference abstracts, and unpublished analyses. Special emphasis is given to more recent sentinel surveillance results and data collected using known, documented methods. Recent trends in HIV prevalence were assessed among sites participating in the three most recent consecutive rounds of antenatal clinic sentinel surveillance. RESULTS: Early HIV surveillance in Rwanda documented high HIV prevalence in urban areas with HIV widely disseminated into rural areas by 1986. Between 1988 and 1996, HIV prevalence among pregnant women ranged from 21% to 33% in Kigali, from 8% to 22% in other urban settings, and from 2% to 12% in rural settings. More recent surveillance among pregnant women has demonstrated more moderate prevalence, with urban/rural differences narrowing slightly. Between 1998 and 2003, HIV prevalence may have declined in urban areas, whereas rural areas appear to have remained stable. Age at first sexual intercourse is relatively late in Rwanda (20 years for both males and females) and has remained stable since at least 1992. CONCLUSIONS: The present analysis suggests that Rwanda may have experienced declines over the long term in HIV prevalence in urban areas, especially in Kigali, and may have stable or slightly rising HIV prevalence in rural areas. The limited behavioural data available suggest that, on the national level, Rwanda may benefit from a unique combination of low numbers of partners and late sexual debut, which may have had a mitigating effect on HIV prevalence.

Adolescent↗
PubMed2006

Prognostic significance of serial magnetic resonance spectroscopies over the course of radiation therapy for patients with malignant glioma.

BACKGROUND: The standard treatment of high grade gliomas (HGG) involves maximal neuro-surgical debulking, followed by post-operative radiotherapy, with or without concurrent chemotherapy, depending on histologic grade. Despite this aggressive strategy, there are few long-term survivors. Proton magnetic resonance spectroscopy (MRS) is a non-invasive imaging method that can monitor metabolic changes in brain tumours. To date there is little data concerning the prognostic significance of the evolving spectral alterations during a course of radiotherapy. MATERIALS: We report herein a prospective study of patients with HGGs undergoing post-operative radiotherapy. Fourteen consecutively eligible patients with a confirmed histologic diagnosis of malignant glioma and completion of all required MRS imaging were included in this study. All patients had MRS imaging prior to radiotherapy, at week 4 of radiotherapy, and 2 months post-treatment. T1 and T2 weighted images as well as post-gadolinium multi-voxel proton MRS images were obtained. Normalized (tumour metabolite/normal brain metabolite) levels of choline, NAA, creatine, lipid and lactate were calculated. Kaplan-Meier (KM) curves of progression-free and overall survival were constructed based on the evolving patterns of metabolite changes over the course of the images. RESULTS: The mean tumour choline/NAA ratio decreased over the course of therapy, with a reduction observed between the baseline and post-radiotherapy studies (1.91 vs. 1.29, P=0.049). A similar decrease was identified with the mean normalized choline ratio, with a highly significant difference observed between the baseline and post-radiation images (1.61 vs. 0.96, P=0.001). Patients who exhibited more than 40% decrease in normalized choline between the week 4 and post-radiotherapy studies were associated with unfavourable survival (logrank test, P=0.003) and disease progression (logrank test, P=0.012). The Lactate/NAA ratio at the 4th week of radiotherapy and the change in normalized choline/creatine between baseline and week 4 of radiotherapy were also predictive of outcome suggesting the possibility of adaptive, response-based radiation treatment. Patients with two or more poor prognostic MRS indices had a significantly shorter progression-free survival compared with those with zero or one poor indices, with 15% and 68% at 1 year, respectively (logrank test, P=0.045). CONCLUSION: The evolving pattern of spectral changes over the course of radiotherapy, in particular those associated with choline-containing compounds, appears to be prognostic of tumour response and outcome. Based on our data, a decision point may exist in the mid course of radical radiotherapy, at which time consideration of the choline levels could indicate the extent of radiotherapeutic response, thus allowing for individualized treatment modification.

Brain Neoplasms↗
PubMed2005

Platinum monolayer on nonnoble metal-noble metal core-shell nanoparticle electrocatalysts for O2 reduction.

We synthesized a new class of O2 electrocatalysts with a high activity and very low noble metal content. They consist of Pt monolayers deposited on the surfaces of carbon-supported nonnoble metal-noble metal core-shell nanoparticles. These core-shell nanoparticles were formed by segregating the atoms of the noble metal on to the nanoparticles' surfaces at elevated temperatures. A Pt monolayer was deposited by galvanic displacement of a Cu monolayer deposited at underpotentials. The mass activity of all the three Pt monolayer electrocatalysts investigated, viz., Pt/Au/Ni, Pt/Pd/Co, and Pt/Pt/Co, is more than order of magnitude higher than that of a state-of-the-art commercial Pt/C electrocatalyst. Geometric effects in the Pt monolayer and the effects of PtOH coverage, revealed by electrochemical data, X-ray diffraction, and X-ray absorption spectroscopy data, appear to be the source of the enhanced catalytic activity. Our results demonstrated that high-activity electrocatalysts can be devised that contain only a fractional amount of Pt and a very small amount of another noble metal.

Letter↗
PubMed2005

Matching supraclavicular fields to the extent of axillary surgery in women prescribed radiotherapy for early stage carcinoma of the breast.

AIMS: To determine (1) if the lower border of a standard anterior radiotherapy field to the supraclavicular fossa matches the upper limit of level II/III axillary dissection; and (2) whether standard lung blocks in patients prescribed axillary radiotherapy shield target axillary tissue in women with breast cancer. MATERIALS AND METHODS: Between 1999 and 2001, 30 women with breast cancer undergoing level II/III axillary dissection had titanium clips placed to define the upper and medial limits of surgery. At radiotherapy planning, a supraclavicular fossa field similar to that described in the UK START trial protocol was simulated, with head twist applied to position the inferior field border (50% isodose) 1 cm below and parallel to the lower border of the clavicle. The field position was recorded on X-ray film. The location of the most superior axillary clip was measured in relation to this inferior field border on the X-ray film. The location of the most medial clip was measured in relation to the lung/chest wall interface. RESULTS: The median distance between the most superior clip and the inferior border of the supraclavicular field was 3.6 cm (0.8-6.9 cm), representing significant underlap in all cases. In addition, five out of 30 (17%) patients had surgical clips over 2.0 cm medial to the lung/chest wall interface, suggesting that medial lymph nodes in an undissected axilla would be shielded by standard lung blocks in patients prescribed axillary radiotherapy. CONCLUSION: Current standard radiation fields to the supraclavicular fossa, as applied in this study, leave apical axillary lymph nodes untreated in a high proportion of patients. Standard lung shielding, as applied in this study to patients simulated for axillary radiotherapy, protect medial axillary lymph nodes in a few patients. A change in practice is recommended.

Adult↗
PubMed2005

Implications of radiation dosimetry of the mandible in patients with carcinomas of the oral cavity and nasopharynx treated with intensity modulated radiation therapy.

Intensity modulated radiation therapy (IMRT) is a newer method of delivering highly conformal, salivary gland sparing radiation treatment that is finding increasing applications in head and neck malignancies. However, the radiation dose distribution to the mandible is rarely considered with IMRT, and the potential risks of osteoradionecrosis or osseointegrated implant failure are not well characterized for this modality. In a series of 10 patients with oral cavity and nasopharyngeal cancers who previously underwent IMRT, examination of the three-dimensional mandibular dose distribution was undertaken. The findings indicate a modest potential risk of osteoradionecrosis and osseointegrated implant failure in cases where IMRT optimization constraints are not specifically aimed at sparing the mandibular bone. Significantly higher mandibular doses (P < 0.04) were received in cases of oral cavity as opposed to nasopharyngeal cancers with IMRT. Efforts to optimize IMRT to further reduce doses to the mandible should be considered, and development of software tools to integrate three-dimensional dose distributions into planning of post-radiotherapy osseointegration would be beneficial.

Carcinoma↗
PubMed2004

Pharmacological evaluation of both enantiomers of (R,S)-BM-591 as thromboxane A2 receptor antagonists and thromboxane synthase inhibitors.

The aim of this work is to evaluate the anti-thromboxane activity of two pure enantiomers of (R,S)-BM-591, a nitrobenzene sulfonylurea chemically related to torasemide, a loop diuretic. The drug affinity for thromboxane A2 receptor (TP) of human washed platelets has been determined. In these experiments, (R)-BM-591 (IC50 = 2.4+/-0.1 nM) exhibited a significant higher affinity than (S)-BM-591 (IC50 = 4.2+/-0.15 nM) for human washed platelets TP receptors. Both enantiomers were stronger ligands than SQ-29548 (IC50 = 21.0+/-1.0 nM) and sulotroban (IC50 = 930+/-42 nM), two reference TXA2 receptor antagonists. Pharmacological characterisations of (S)-BM-591 and (R)-BM-591 were compared in several models. Thus, (R)-BM-591 strongly prevented platelet aggregation induced by arachidonic acid (AA) (600 microM) and U-46619 (1 microM) while (S)-BM-591 showed a lower activity. On isolated tissues pre-contracted by U-46619, a stable TXA2 agonist, (S)-BM-591 was more potent in relaxing guinea-pig trachea (EC50 = 0.272+/-0.054 microM) and rat aorta (EC50 = 0.190+/-0.002 microM) than (R)-BM-591 (EC50 of 9.60+/-0.63 microM and 0.390+/-0.052 microM, respectively). Moreover, at 1 microM, (R)-BM-591 totally inhibited TXA2 synthase activity, expressed as TXB2 production from human platelets, while at the same concentration, (S)-BM-591 poorly reduced the TXB2 synthesis (22%). Finally, in rats, both enantiomers lost the diuretic activity of torasemide. In conclusion, (R)-BM-591 exhibits a higher affinity and antagonism on human platelet TP receptors than (S)-BM-591 as well as a better thromboxane synthase inhibitory potency. In contrast, (S)-BM-591 is more active than the (R)-enantiomer in relaxing smooth muscle contraction of rat aorta and trachea guinea pig. Consequently, (R)-BM-591 represents the best candidate for further development in the field of thrombosis disorders.

Animals↗
PubMed2004

Baseline FACT-G score is a predictor of survival for advanced lung cancer.

UNLABELLED: The objective of this study is to evaluate whether patient-reported baseline health-related quality of life (HRQL) measured by the Functional Assessment of Cancer Therapy-General (FACT-G) instrument is predictive of survival for patients with advanced lung cancer. METHODS: Consecutive patients with advanced lung cancer planning to undergo palliative chemotherapy in the outpatient clinics of a Canadian tertiary care cancer centre were enrolled on study. FACT-G total scores and clinical predictors of survival (age, sex, histology, stage of disease, previous weight loss, presence of liver metastases and performance status) were prospectively collected at baseline. Survival data was subsequently collected retrospectively from the Alberta Cancer Registry. Stratified Cox Proportional Hazards analysis was done examining the influence of baseline total FACT-G scores on survival, controlling for potential clinical confounders. RESULTS: Median survival of the 42 patient cohort was 9.9 months with a 2-year survival of 16.7%. Multivariate analysis indicated that baseline FACT-G total score is significantly associated with survival (p = 0.004). CONCLUSION: Baseline HRQL is a statistically significant predictor of survival for patients with advanced lung cancer. When used along with traditional clinical factors, patient-reported baseline HRQL assessment using the FACT-G provides additional prognostic information to the patient and clinician.

Adult↗
PubMed2003

Characterization of HLA DR2 and DQ8 transgenic mouse with a new engineered mouse class II deletion, which lacks all endogenous class II genes.

Human autoimmune diseases are a class of complex immune system disorders characterized by loss of tolerance to self-antigens. HLA class II molecules play a central role in the initiation, propagation and prolongation of the disease process. HLA class II transgenic mice with mouse endogenous class II gene Ab knockout were used successfully in several mouse models for human autoimmune diseases, such as IDDM, SLE and EAE in our Lab. However, these mice carry the functional mouse Eb gene from the Abeta(0/0) construct and could express Ebeta/DRalpha(Ealpha) molecules and shape the T cell repertoire in these mice. Recently, we have obtained the new MHCII(Delta/Delta) mice that are devoid of all endogenous conventional mouse MHC class II genes. When these mice are mated with our HLA class II transgenic mice, only human class II genes are expressed. The DR and DQ molecules expressed in these mice shape the T cell repertoire and regulate the immune response. Therefore, this new class of HLA transgenic mice is the first to be completely "humanized" in their MHC class II genes and will be an invaluable mouse model for human MHC class II associated autoimmune diseases.

Animals↗
PubMed2002

A pilot survey of medical students' perspectives on their educational exposure to palliative care in two Canadian universities.

BACKGROUND: Graduating medical students from the class of 1999 from McGill University and the University of Alberta completed a self-administered, anonymous, pilot survey to determine students' perspectives on how their educational experience in common palliative care topics contrasted with their educational experience in the diagnosis and management of hypertension, non palliative aspects of breast cancer, and patients dying of acquired immune deficiency syndrome (AIDS). METHODS: A Likert scale ranging from "excellent," scored 1, "very poor," scored 5, was used. Students also estimated the number of hours they spent, during their training, in operating rooms, on home visits to terminally ill patients, and in interprofessional teaching. RESULTS: Sixty of 114 (53%) students from McGill University, and 53 of 110 (48%) students from the University of Alberta responded to the survey. The mean ratings of education experience in the various topics for both universities combined were as follows: hypertension, 2.03; breast cancer, 2.33; cancer pain, 3.42; communicating with dying patients, 3.32; and caring for patients with AIDS, 4.15. The average number of hours spent in the operating room, on home visits to terminally patients, and in interprofessional teaching for both universities combined were 155 hours, 4.2 hours, and 16 hours, respectively. Of the responding students from both universities 83% favored increased palliative care teaching. CONCLUSION: Despite the disproportionate number of hours spent in operating rooms compared to palliative care community exposure, only two students, one from each university, favored shortening surgical rotations to allow for increased time for palliative care education. Recommendations, including increasing palliative care education during clinical clerkships, are provided to improve medical students' perceptions of their educational experiences in palliative care education.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Persistent preswitch clonotypic myeloma cells correlate with decreased survival: evidence for isotype switching within the myeloma clone.

Multiple myeloma (MM) is identified by unique immunoglobulin heavy chain (IgH) variable diversity joining region gene rearrangements, termed clonotypic, and an M protein termed the "clinical" isotype. Transcripts encoding clonotypic pre and postswitch IgH isotypes were identified in MM peripheral blood mononuclear cells (PBMCs), bone marrow (BM), and mobilized blood. For 29 patients, 38 BM, 17 mobilized blood, and 334 sequential PBMC samples were analyzed at diagnosis, before and after transplantation for 2 to 107 months. The clinical clonotypic isotype was readily detectable and persisted throughout treatment. Eighty-two percent of BM and 38% of PBMC samples also expressed nonclinical clonotypic isotypes. Clonotypic immunoglobulin M (IgM) was detectable in 68% of BM and 25% of PBMC samples. Nonclinical clonotypic isotypes were detected in 41% of mobilized blood samples, but clonotypic IgM was detected in only 12%. Patients with persistent clonotypic IgM expression had adverse prognostic features at diagnosis (lower hemoglobin, higher beta(2)-microglobulin) and higher numbers of BM plasma cells compared with patients with infrequent/absent clonotypic IgM. Patients with persistent clonotypic IgM expression had significantly poorer survival than patients with infrequent IgM expression (P <.0001). In a multivariate analysis, persistent clonotypic IgM expression in the blood correlated independently with poor survival (P =.01). In nonobese diabetic severe combined immunodeficiency mice, xenografted MM cells expressed clinical and nonclinical postswitch clonotypic isotypes. MM expressing clonotypic IgM engrafted both primary and secondary mice, indicating their persistence within the murine BM. This study demonstrates that MM clonotypic cells expressing preswitch transcripts are tied to disease burden and outcomes. Because MM pathology involves postswitch plasma cells, this raises the possibility that IgH isotype switching in MM may accompany worsening disease.

Adult↗
PubMed2001

Muscle-invasive transitional cell carcinoma of the urinary bladder: a population-based study of patterns of care and prognostic factors.

PURPOSE: Population-based cancer registries can permit the study of the survivorship of all patients with a particular diagnosis regardless of patterns of referral and practice within a specific geographic distribution. The purpose of this study is to describe the patterns of care, outcome, and prognostic factors for bladder cancer in the northern region of the province of Alberta, Canada, between 1984 and 1993. METHODS AND MATERIALS: Between 1984 and 1993, 184 patients from northern Alberta were identified from the Alberta Cancer Registry as having undergone curative treatment for biopsy-proven muscle-invasive transitional cell carcinoma of the bladder. Data were obtained, by retrospective chart review, regarding the staging, pathology, treatment, and outcome of patients treated in the northern Alberta cities of Edmonton, Grande Prairie, and Red Deer, regardless of the responsible treating institution. The prognostic significance of patient-, tumor-, and treatment-related variables were tested using univariate and multivariate analysis using the Cox proportional-hazard model. RESULTS: As the primary treatment modality, 74 patients (40%) received radical radiotherapy (RT) without surgery; surgery was used alone in 81 patients (44%), and was combined with preoperative or postoperative radiotherapy in 29 patients (16%). Seventy-three (40%) patients also received concurrent, neoadjuvant, or adjuvant chemotherapy. The Kaplan-Meier estimate of median survival was 2.2 years, and the 5-year overall survival was 30%. Univariate analysis demonstrated the prognostic significance of T classification (p < 0.001), lymph node involvement (p < 0.001), complete response to RT (p = 0.001), hydronephrosis (p = 0.017), and vascular/lymphatic involvement (p = 0.035). Multivariate analysis revealed the following to have a significant association with survival: T classification (p = 0.001), lymph node involvement (p = 0.004), complete response to RT (p = 0.054), hydronephrosis (p = 0.019), and use of chemotherapy in the treatment regimen (p = 0.025). CONCLUSION: The strongest prognostic factors in this study were tumor related, and no significant differences in survival were detected between patients treated with primary surgery vs. organ-preservation approaches. A survival advantage associated with the incorporation of chemotherapy into the management schema was detected on multivariate, but not univariate, analysis. Stratification of patients based on tumor characteristics is imperative in clinical trials for invasive bladder cancer. Novel treatment approaches are required to improve survival further in patients with apparently localized disease.

Adult↗
PubMed2001

Dosimetric evaluation of lung tumor immobilization using breath hold at deep inspiration.

PURPOSE: To examine the dosimetric benefit of self-gated radiotherapy at deep-inspiration breath hold (DIBH) in the treatment of patients with non-small-cell lung cancer (NSCLC). The relative contributions of tumor immobilization at breath hold (BH) and increased lung volume at deep inspiration (DI) in sparing high-dose lung irradiation (> or = 20 Gy) were examined. METHODS AND MATERIALS: Ten consecutive patients undergoing radiotherapy for Stage I-IIIB NSCLC who met the screening criteria were entered on this study. Patients were instructed to BH at DI without the use of external monitors or breath-holding devices (self-gating). Computed tomography (CT) scans of the thorax were performed during free breathing (FB) and DIBH. Fluoroscopy screened for reproducible tumor position throughout DIBH, and determined the maximum superior-inferior (SI) tumor motion during both FB and DIBH. Margins used to define the planning target volume (PTV) from the clinical target volume included 1 cm for setup error and organ motion, plus an additional SI margin for tumor motion, as determined from fluoroscopy. Three conformal treatment plans were then generated for each patient, one from the FB scan with FB PTV margins, a second from the DIBH scan with FB PTV margins, and a third from the DIBH scan with DIBH PTV margins. The percent of total lung volume receiving > or = 20 Gy (using a prescription dose of 70.9 Gy to isocenter) was determined for each plan. RESULTS: Self-gating at DIBH was possible for 8 of the 10 patients; 2 patients were excluded, because they were not able to perform a reproducible DIBH. For these 8 patients, the median BH time was 23 (range, 19-52) s. The mean percent of total lung volume receiving > or = 20 Gy under FB conditions (FB scan with FB PTV margins) was 12.8%. With increased lung volume alone (DIBH scan with FB PTV margins), this was reduced to 11.0%, tending toward a significant decrease in lung irradiation over FB (p = 0.086). With both increased lung volume and tumor immobilization (DIBH scan with DIBH PTV margins), the mean percent lung volume receiving > or = 20 Gy was further reduced to 8.8%, a significant decrease in lung irradiation compared to FB (p = 0.011). Furthermore, at DIBH, the additional benefit provided by tumor immobilization (i.e., using DIBH instead of FB PTV margins) was also significant (p = 0.006). The relative contributions of tumor immobilization and increased lung volume toward reducing the percent total lung volume receiving > or = 20 Gy were patient specific; however, all 8 of the patients analyzed showed a dosimetric benefit with this DIBH technique. CONCLUSION: Compared to FB conditions, at DIBH the mean reduction in percent lung volume receiving > or = 20 Gy was 14.3% with the increase in lung volume alone, 22.1% with tumor immobilization alone, and 32.5% with the combined effect. The dosimetric benefit seen at DIBH was patient specific, and due to both the increased lung volume seen at DI and the PTV margin reduction seen with tumor immobilization.

Aged↗