19 resultados para chi-squared distribution
em QUB Research Portal - Research Directory and Institutional Repository for Queen's University Belfast
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In this research, an agent-based model (ABM) was developed to generate human movement routes between homes and water resources in a rural setting, given commonly available geospatial datasets on population distribution, land cover and landscape resources. ABMs are an object-oriented computational approach to modelling a system, focusing on the interactions of autonomous agents, and aiming to assess the impact of these agents and their interactions on the system as a whole. An A* pathfinding algorithm was implemented to produce walking routes, given data on the terrain in the area. A* is an extension of Dijkstra's algorithm with an enhanced time performance through the use of heuristics. In this example, it was possible to impute daily activity movement patterns to the water resource for all villages in a 75 km long study transect across the Luangwa Valley, Zambia, and the simulated human movements were statistically similar to empirical observations on travel times to the water resource (Chi-squared, 95% confidence interval). This indicates that it is possible to produce realistic data regarding human movements without costly measurement as is commonly achieved, for example, through GPS, or retrospective or real-time diaries. The approach is transferable between different geographical locations, and the product can be useful in providing an insight into human movement patterns, and therefore has use in many human exposure-related applications, specifically epidemiological research in rural areas, where spatial heterogeneity in the disease landscape, and space-time proximity of individuals, can play a crucial role in disease spread.
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The purpose of this study was to determine whether the prevalence and severity of gingival overgrowth in renal transplant recipients concomitantly treated with cyclosporin and a calcium channel blocker was associated with functional polymorphisms within the signal sequence of the transforming growth factor-(TGF)beta1 gene.
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Vascular endothelial growth factor (VEGF) is reported to be implicated in the development of diabetic nephropathy. We performed a case-control study to determine if VEGF-2578C -> A, VEGF-1499C -> T, and VEGF-635G -> C single-nucleotide polymorphisms (SNPs) in the VEGF gene are associated with predisposition to diabetic nephropathy in type I diabetes. Genomic DNA was obtained from Irish type I diabetic individuals with nephropathy (cases, n=242) and those without nephropathy (controls, n=301), in addition to 400 healthy control samples. These samples were genotyped for the three SNPs using TaqMan or Pyrosequencing technology. Chi-squared analyses revealed no significant differences in genotype or allele frequencies in cases versus controls for VEGF-2578C -> A (genotype, P=.58; allele, P=.52) and VEGF-635G -> C (genotype, P=.58; allele, P=.33). However, a positive association with diabetic nephropathy was observed for the VEGF-1499T allele in the Northern Ireland population (P
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The aim of this paper was to confirm the factor structure of the 20-item Beck Hopelessness Scale in a non-clinical population. Previous research has highlighted a lack of clarity in its construct validity with regards to this population.
Based on previous factor analytic findings from both clinical and non-clinical studies, 13 separate confirmatory factor models were specified and estimated using LISREL 8.72 to test the one, two and three-factor models.
Psychology and medical students at Queen's University, Belfast (n = 581) completed both the BHS and the Beck Depression Inventory (BDI).
All models showed reasonable fit, but only one, a four-item single-factor model demonstrated a nonsignificant chi-squared statistic. These four items can be used to derive a Short-Form BHS (SBHS) in which increasing scores (0-4) corresponded with increasing scores in the BDI. The four items were also drawn from all three of Beck's proposed triad, and included both positively and negatively scored items.
This study in a UK undergraduate non-clinical population suggests that the BHS best measures a one-factor model of hopelessness. It appears that a shorter four-item scale can also measure this one-factor model. (C) 2011 Elsevier Ltd. All rights reserved.
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Purpose: The aim of this study is to describe the ocular and demographic features of Caucasian patients newly presenting with primary angle closure glaucoma and the proportion of workload it represents at a tertiary university hospital glaucoma service. Methods: A retrospective case notes review was conducted for all Caucasian patients newly diagnosed with narrow angles, primary angle closure, acute primary angle closure and primary angle closure glaucoma that were seen over a period of 2 years. Demographic and ocular variables were compared and statistical analysis was carried out with the paired t -test and chi-squared test. Number of primary open angle closure glaucoma and acute angle closure cases were compared with total number of new referrals to the department, new patients diagnosed with glaucoma and population numbers for the North East of Scotland. Results: One hundred and four patients were analysed. Twenty-four (23.1%) had narrow angles, 30 (28.8%) had primary angle closure and 50 (48.1%) had primary angle closure glaucoma. Twelve (11.5%) presented with acute primary angle closure. There was no significant difference for gender, age, hypermetropia or visual acuity between groups. Primary angle closure glaucoma constituted 22.9% (50/128) of newly diagnosed glaucoma cases. Based on the 2001 Scotland census, the crude annual incidence of newly diagnosed primary angle closure glaucoma was estimated at 14.8 per 100000 and 3.6 per 100000 for acute primary angle closure in the over-45-year-old population. Conclusion: Our study confirms that primary angle closure glaucoma is uncommon in Caucasians, but not as rare as originally perceived as it makes up a fair proportion (22.9%) of glaucoma workload. © 2009 The Authors Journal Compilation © 2009 Royal Australian and New Zealand College of Ophthalmologists.
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Determination of HER2 protein expression by immunohistochemistry (IHC) and genomic status by fluorescent in situ hybridisation (FISH) are important in identifying a subset of high HER2-expressing gastric cancers that might respond to trastuzumab. Although FISH is considered the standard for determination of HER2 genomic status, brightfield ISH is being increasingly recognised as a viable alternative. Also, the impact of HER2 protein expression/genomic heterogeneity on the accuracy of HER2 testing has not been well studied in the context of gastric biopsy samples.
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Background: Sun exposure increases risk of skin cancer, especially melanoma, incidence of which continues to rise. Reported skin cancer knowledge and trends in sun care behaviours are documented in a UK region where there has been 20 years of sun-related health promotion campaigns. Methods: In 2000, 2004 and 2008, a 'care in the sun' module was included in the Northern Ireland (NI) Omnibus survey. Randomly selected subjects were asked to complete a sun-related questionnaire and proportions of respondents analysed by demographic and socio-economic factors, with differences tested using z-tests and the chi-squared test. Results: Around 3623 persons responded. Skin cancer knowledge was high (97). Sun avoidance decreased with time and was lowest among younger age groups and males. Sunscreen use was high (70), unchanged over 8 years, and more likely among younger age groups, females, those in paid employment, and those with tertiary level education. Use of sunscreen with minimum Sun Protection Factor (SPF) 15 (a campaign message) increased from 45 to 70 (P
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CD2-associated protein (CD2AP) is essential for podocyte function. CD2AP mutations have been found in patients with focal segmental glomerulosclerosis, a disease histologically resembling diabetic nephropathy and often progressing to end-stage renal disease (ESRD). We hypothesised that variations in the CD2AP gene may contribute to susceptibility to glomerular injury in diabetes and investigated if single-nucleotide polymorphisms (SNPs) in CD2AP are associated with diabetic nephropathy in patients with type 1 diabetes. The discovery cohort consisted of 2,251 Finnish patients with type 1 diabetes. SNPs were selected from the HapMap database to cover the CD2AP gene. The associations between genotyped SNPs and diabetic nephropathy or ESRD were analysed with the chi-squared test and logistic regression. Three SNPs were selected for replication in cohorts from Denmark, Italy, the United Kingdom and Ireland. None of the 15 successfully genotyped SNPs were associated with diabetic nephropathy when compared to patients with normal albumin excretion rate. However, when genotype frequencies in patients with ESRD were compared with all other patients, two CD2AP SNPs, rs9369717 and rs9349417, were found to be associated with ESRD. The meta-analysis of the original and two additional European cohorts resulted in significant p values
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Aim This study aimed to document developments in rectal cancer services in a UK population and evaluate changes in outcome over a 10-year period.
Method Patients diagnosed with primary rectal carcinoma in 1996, 2001 and 2006 were identified by the Northern Ireland Cancer Registry. Data were retrospectively collected on presentation, investigation, treatment and staging. Differences over the period were analysed using the chi-squared test; Kaplan–Meier and Cox regression tests were used for survival analysis.
Results After exclusions there were 636 patients, including 187 presenting in 1996, 203 in 2001 and 246 in 2006. The use of preoperative MRI of the rectum, endorectal ultrasound and abdominal CT increased during the study period. For patients treated by surgery, total mesorectal excision (TME) increased from 19% in 1996 to 64% in 2006 (P < 0.001). The use of radiotherapy (27% in 1996, 47% in 2006) and chemotherapy (21% in 1996, 32% in 2006) increased. The overall 5-year survival improved significantly between 1996 and 2006 from 34% in 1996 to 45% in 2006 (P = 0.02). Among patients having surgery, 5-year survival increased from 43% in 1996 to 63% in 2006 (P < 0.001). Multivariate analysis showed that the improvement in survival was associated with TME and chemotherapy, while radiotherapy was not.
Conclusion Survival of patients with rectal cancer in Northern Ireland has improved significantly over the last decade, probably due to the increased use of TME and chemotherapy.
Keywords Surgery, rectum, oncology
What does this paper add to the literature?
This population-based study demonstrates a significant improvement in survival over recent years of rectal cancer patients in Northern Ireland. It concludes that surgical resection with TME and chemotherapy have had a significant impact on survival and that the improvement was not due to a stage-migration effect.
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Aims: Systematic review of mortality in childhood-/adolescent-diagnosed Type 1 diabetes and examination of factors explaining the mortality variation between studies.
Methods: Relevant studies were identified from systematic searches of MEDLINE and EMBASE. Observed and expected numbers of deaths were extracted, and standardised mortality ratios (SMRs) and 95 % confidence intervals (CIs) were calculated. Negative binomial regression was used to investigate association between mortality and study/country characteristics.
Results: Thirteen relevant publications with mortality data were identified describing 23 independent studies. SMRs varied markedly ranging from 0 to 854 (chi-squared = 70.68,df = 21, p<0.0001). Significant associations were observed between SMR and mid-year of follow-up [incidence rate ratio (IRR) 0.95, 95 % CI 0.91–0.99 equivalent to a 5 % decrease per year], between SMR and infant mortality rate (IRR 1.07, 95 % CI 1.02–1.12, a 7 % increase for each death per 1,000 live births) and, after omitting an outlier, between SMR and health expenditure as a percentage of gross domestic product (GDP) (IRR 0.79, 95 % CI 0.68–0.93, a 21 % decrease for each one percent increase in GDP). No relationship was detected between SMR and a country’s childhood diabetes incidence rate or GDP.
Conclusions: Excess mortality in childhood-/adolescent diagnosed Type 1 diabetes is apparent across countries worldwide. Excesses were less marked in more recent studies and in countries with lower infant mortality and higher health expenditure.
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BACKGROUND: Neisseria meningitidis can cause severe infection in humans. Polymorphism of Complement Factor H (CFH) is associated with altered risk of invasive meningococcal disease (IMD). We aimed to find whether polymorphism of other complement genes altered risk and whether variation of N. meningitidis factor H binding protein (fHBP) affected the risk association.
METHODS: We undertook a case-control study with 309 European cases and 5,200 1958 Birth Cohort and National Blood Service cohort controls. We used additive model logistic regression, accepting P<0.05 as significant after correction for multiple testing. The effects of fHBP subfamily on the age at infection and severity of disease was tested using the independent samples median test and Student's T test. The effect of CFH polymorphism on the N. meningitidis fHBP subfamily was investigated by logistic regression and Chi squared test.
RESULTS: Rs12085435 A in C8B was associated with odds ratio (OR) of IMD (0.35 [95% CI 0.19-0.67]; P = 0.03 after correction). A CFH haplotype tagged by rs3753396 G was associated with IMD (OR 0.56 [95% CI 0.42-0.76], P = 1.6x10-4). There was no bacterial load (CtrA cycle threshold) difference associated with carriage of this haplotype. Host CFH haplotype and meningococcal fHBP subfamily were not associated. Individuals infected with meningococci expressing subfamily A fHBP were younger than those with subfamily B fHBP meningococci (median 1 vs 2 years; P = 0.025).
DISCUSSION: The protective CFH haplotype alters odds of IMD without affecting bacterial load for affected heterozygotes. CFH haplotype did not affect the likelihood of infecting meningococci having either fHBP subfamily. The association between C8B rs12085435 and IMD requires independent replication. The CFH association is of interest because it is independent of known functional polymorphisms in CFH. As fHBP-containing vaccines are now in use, relationships between CFH polymorphism and vaccine effectiveness and side-effects may become important.
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Purpose:Physical activity is recommended for optimal prevention of cardiovascular disease(CVD) and participation in sport is associated with improved well-being. However, people with long-standing illness/disability are less likely to participate in sport than others. Evidence of factors associated with their participation is limited and the best approach to encourage participation is unknown. This study aimed to identify sport participation levels and their correlates, among adults with long standing illness/disability in Northern Ireland, where CVD prevalence is high. Method:Using routinely collected data in annual surveys of population samples from 2007 to 2011, descriptive statistics were derived. Chi-squared tests were used to compare characteristics of those with a long-term illness/disability and those without long-term health problems. Uni-variate binary regression analysis for the whole sample and those with a long-standing illness/disability, using sport participation as the dependent variable, was performed and variables with a p-value of 0.1 or less were taken into a multi-variate analysis. Results:The sample included 13,683 adults; 3550(26%) reported having long-term illness/disability. Fewer of those with, than without, long-term illness/disability reported sport participation in the previous year (868/3550(24.5%) v 5615/10133(55.6%)). Multi-variate analysis showed that, for those with long-standing illness/disability, being single and less socio-economically deprived correlated positively with sport participation. For both those with long-standing illness/disability and the full sample, sport participation correlated positively with being male, aged <56 years, access to a household car/van, sports club membership, health ‘fairly good’ or ‘good’ in the previous year, doing paid/unpaid work, and living in an urban location. For the full sample but not those with long-standing illness/disability, sport participation correlated positively with being a non-smoker, higher educational status and personal internet access. Of note, personal internet access was less for those with, than without, long-term illness/disability (41% v 70%). Conclusions:Efforts to promote physical activity in sport for those with long-standing illness/disability should target older people, married females, those who live rurally, and those who are socio-economically deprived and report their health as ‘not good’. Implementation of initiatives should not rely on the internet, to which these people may not have ready access, to help support their sport participation and physical activity in optimal CVD prevention.
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We investigated the role of the C1772T polymorphisms in exon 12 of the Hypoxia-inducible factor-1 alpha (HIF-1alpha) gene C1772T genotype in prostate cancer (PCa) and amplification of the hypoxic response. We identified the heterozygous germline CT genotype as an increased risk factor for clinically localised prostate cancer (Odds ratio = 6.2; p < 0.0001). While immunostaining intensity for HIF-1alpha and VEGF was significantly enhanced in 75% of PCa specimens when compared to matched benign specimens (p < 0.0001), the CT genotype did not modulate the kinetics of HIF-1alpha protein expression in hypoxia in vitro, and was not associated with enhanced expression of hypoxic biomarkers. This study provides the first evidence of an increased risk for clinically localised prostate cancer in men carrying the C1772T HIF-1alpha gene polymorphism. Although our results did not suggest an association between expression of hypoxic biomarkers and genotype status, the correlation may merit further investigation.
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We assessed motor laterality in sheep to explore species-specific brain hemi-field dominance and how this could be affected by genetic or developmental factors. Further, we investigated whether directionality and strength of laterality could be linked to emotional stress in ewes and their lambs during partial separation. Forty-three ewes and their singleton lambs were scored on the (left/right) direction of turn in a y-maze to rejoin a conspecific (laterality test). Further, their behavioural response (i.e. time spent near the fence, vocalisations, and activity level) during forced separation by an open-mesh fence was assessed (separation test). Individual laterality was recorded for 44.2 % ewes (significant right bias) and 81.4 % lambs (equally biased to the left and the right). There was no significant association in side bias between dams and offspring. The Chi-squared test revealed a significant population bias for both groups (p < 0.05). Evolutionary adaptive strategies or stimuli-related visual laterality may provide explanation for this decision-making process. Absolute strength of laterality (irrespective of side) was high (Kolmogorov–Smirnov test, dams: D = 0.2; p < 0.001; lambs: D = 0.36, p < 0.0001). The Wilcoxon test showed that lateralised lambs and dams spent significantly more time near each other during separation than non-lateralised animals (p < 0.05), and that lateralised dams were also more active than non-lateralised ones. Arguably, the lateralised animals showed a greater attraction to their pair because they were more disturbed and thus required greater reassurance. The data show that measures of laterality offer a potential novel non-invasive indicator of separation stress.
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Introduction
The role of the pharmacist centers on ensuring the safe and effective use of medicines, including over-the-counter (OTC) medicines. It is important to ascertain pharmacy students’ use and opinions on OTC medicines, given that they are the pharmacists of the future and that this market continues to expand. This study aimed to investigate Queen’s University Belfast (QUB) final year pharmacy students’ use and views on OTC medicines. Scarce work has been conducted in this area to date.
Methods
Following ethical approval and a pilot study, all students (n=155) were invited to participate in a self-completed questionnaire (n=20 questions), distributed at a mandatory class. Descriptive statistics and non-parametric tests (Chi-squared and Mann Whitney U-test) were used for data analyses.
Results
The response rate was 99.4% (154/155). The majority (153/155) reported using OTC medicines; the key consideration during personal product selection was effectiveness. Most [96.1% (147/153)] were in agreement that safety was the over-riding concern during OTC consultations. While 96.1% (149/155) considered that using an evidence-based approach improved the quality of patient care, 68.0% (104/153) would be prepared to sell a product that lacks evidence of effectiveness, provided it would not cause harm.
Conclusions
The importance of evidence of effectiveness was acknowledged, yet many students in this study were prepared to recommend unproven products. Further strategies are required at QUB to ensure this routine consideration alongside safety in practice.