Why Clinicians Prognosticate Stroke Patients Poorly: Results from the Clinician Judgment versus Risk Score to Predict Stroke Outcomes Randomized Study.

BACKGROUND: Prognostication after a stroke has important implications for care and for decisions made by patients and their families. It is not clear why clinicians, even experienced stroke neurologists, poorly estimate the risk of disability and death following stroke. METHODS: We analyzed the results from the Clinician Judgment versus Risk Score to predict Stroke Outcomes study in which each clinician estimated the risk of death and the risk of death or disability in 5 case-based ischemic stroke scenarios. We employed a mixed-effect linear model to disentangle the ability of clinicians to discriminate between poor and good prognosis cases (slope) from the calibration of quantitative estimates (intercept), and to assess for any effect of anchoring in the death or disability condition (through a comparison with the death condition). RESULTS: One hundred eleven clinicians made 1665 predictions. Clinicians were able to discriminate between cases with low and high risks of death (slope of .81, 95% confidence interval [CI] .70-.93), but the quantitative estimates were not well calibrated (intercept of 5.14, 95% CI 3.97-6.33). The discrimination was poorer (slope of .67, 95% CI .60-.75), but the calibration was better (intercept of -.34, 95% CI -5.43 to 4.98) in the death or disability estimates. CONCLUSION: Poor stroke prognostication can be explained by poor calibration and an anchoring effect, which are both amenable to specific training interventions.

Research recruitment practices and critically ill patients. A multicenter, cross-sectional study (the Consent Study).

RATIONALE: Limited cross-sectional data exist to characterize the challenges of enrolling critically ill patients into research studies. OBJECTIVES: We aimed to describe recruitment practices, document factors that impact recruitment, and identify factors that may enhance future research feasibility. METHODS: We conducted a prospective, observational study of all critically ill adults eligible to participate in research studies at 23 Canadian intensive care units. We characterized eligibility events into one of five consent outcomes, identified reasons why opportunities to recruit were missed or infeasible, and documented decision maker's rationale for providing or declining consent. MEASUREMENTS AND MAIN RESULTS: Patients made decisions for themselves in 8.9% of encounters. In 452 eligibility events, consent was not required in 14 (3.1%), missed in 130 (28.8%), infeasible due to operational reasons in 129 (28.5%), obtained in 140 (31.0%), and declined in 39 (8.6%). More than half (57.3%) of all opportunities to recruit patients were missed or infeasible, largely because of research team workload, limited availability, narrow time windows for inclusion, difficulties in contacting families, nonexistent substitute decision makers (SDMs), physician refusals, and protocols prohibiting coenrollment. The rationale for providing consent differed between patients and SDMs. Greater research coordinator experience and site research volume and broader time windows for inclusion were significant predictors of fewer declined consents. CONCLUSIONS: A large gap exists between eligibility and the frequency with which consent encounters occur in intensive care unit research. Recruitment is susceptible to design and procedural inefficiencies that hinder recruitment and to personnel availability, given the need to interact with SDMs. Current enrollment practices may underrepresent potential study populations.

A prescription at discharge improves long-term adherence for secondary stroke prevention.

BACKGROUND: Medication adherence is important for optimal secondary stroke prevention. We evaluated short-term adherence to antihypertensive and lipid-lowering agents after a new ischemic stroke, as predictor of adherence at 1 and 2 years. METHODS: A 5-year cohort of patients from 11 institutions in the Registry of the Canadian Stroke Network was linked to population-based administrative health records. Patients diagnosed with acute ischemic stroke and discharged home were included. Medication adherence was assessed through documented prescription filling at 7 days, 1 year, and 2 years. RESULTS: From 2003 to 2008, 6437 ischemic stroke patients were discharged home from hospital, and 1126 patients filled a prescription for antihypertensive and lipid-lowering agents within 7 days of discharge. Patients provided with a prescription at discharge were more likely to show adherence at 7 days. Adherence at 1 year remains higher in these patients for antihypertensive (93.8% vs. 87.7%; odds ratio [OR], 2.31; 95% confidence interval [CI], 1.69-3.16), lipid-lowering agents (88% vs. 81.6%; OR, 1.77; 95% CI, 1.36-2.32), or both (85.8% vs. 79.9%; OR, 1.72; 95% CI, 1.32-2.25). Findings are similar at 2 years for antihypertensive (92.2% vs. 87.7%; OR, 1.78; 95% CI, 1.3-2.43), lipid-lowering agents (82.6% vs. 79.0%; OR, 1.31; 95% CI, 1.01-1.69), or both (81.1% vs. 77.0%; OR, 1.4; 95% CI, 1.09-1.82). CONCLUSIONS: Provision of a prescription strengthens adherence at 1 week from discharge for both prior and new users of antihypertensive and lipid-lowering drugs. Medication adherence at 1 week after discharge for acute ischemic stroke predicts adherence for secondary preventive therapies at 1 and 2 years.

Patient-Reported Outcomes After Tetralogy of Fallot Repair.

BACKGROUND: Comprehensive assessment of tetralogy of Fallot (TOF) outcomes extends beyond morbidity and mortality to incorporate patient-reported outcomes (PROs), including quality of life (QOL) and health status (HS). OBJECTIVES: This study explored PROs in adolescents and adults with TOF and delineated variables associated with PROs. METHODS: This was a cross-sectional observational study within a larger prospective registry of adolescents and adults with repaired TOF and moderate or greater pulmonary regurgitation from North America, Europe, and Asia. Participants completed PROs, including a QOL linear analogue scale (QOL-LAS) and an HS visual analogue scale (HS-VAS). Scores were classified according to age cohorts: <18, 18 to 25, 26 to 40, and >40 years. RESULTS: The study included 607 patients (46.3% female; median age 28.5 years). Median QOL-LAS scores (0-100) were similar across age cohorts (85, 80, 80, 80; P = 0.056). Median HS-VAS scores (0-100) were lowest for the oldest cohort (77) compared with the 3 younger cohorts (85, 80, 80) (P = 0.004). With advancing age, there were increased reports of poor mobility (P < 0.001) and pain or discomfort (P = 0.004); problems in these dimensions were reported by 19.1% and 37.2% of patients aged >40 years, respectively. Of factors associated with superior PROs on multivariable regression modeling (ie, being White, being nonsyndromic, having employment, and having better left ventricular function; P < 0.05), asymptomatic status (functional class I) was the variable associated with the greatest number of QOL and HS measures (P < 0.001). CONCLUSIONS: Strategies to improve TOF outcomes should consider PROs alongside conventional clinical variables. Factors associated with poorer PROs represent opportunities to intervene to improve the lives of patients with TOF.

IScore: a risk score to predict death early after hospitalization for an acute ischemic stroke.

BACKGROUND: A predictive model of stroke mortality may be useful for clinicians to improve communication with and care of hospitalized patients. Our aim was to identify predictors of mortality and to develop and validate a risk score model using information available at hospital presentation. METHODS AND RESULTS: This retrospective study included 12 262 community-based patients presenting with an acute ischemic stroke at multiple hospitals in Ontario, Canada, between 2003 and 2008 who had been identified from the Registry of the Canadian Stroke Network (8223 patients in the derivation cohort, 4039 in the internal validation cohort) and the Ontario Stroke Audit (3720 for the external validation cohort). The mortality rates for the derivation and internal validation cohorts were 12.2% and 12.6%, respectively, at 30 days and 22.5% and 22.9% at 1 year. Multivariable predictors of 30-day and 1-year mortality included older age, male sex, severe stroke, nonlacunar stroke subtype, glucose ≥7.5 mmol/L (135 mg/dL), history of atrial fibrillation, coronary artery disease, congestive heart failure, cancer, dementia, kidney disease on dialysis, and dependency before the stroke. A risk score index stratified the risk of death and identified low- and high- risk individuals. The c statistic was 0.850 for 30-day mortality and 0.823 for 1-year mortality for the derivation cohort, 0.851 for the 30-day model and 0.840 for the 1-year mortality model in the internal validation set, and 0.790 for the 30-day model and 0.782 for the 1-year model in the external validation set. CONCLUSION: Among patients with ischemic stroke, factors identifiable within hours of hospital presentation predicted mortality risk at 30 days and 1 year. The predictive score may assist clinicians in estimating stroke mortality risk and policymakers in providing a quantitative tool to compare facilities.

The iScore predicts poor functional outcomes early after hospitalization for an acute ischemic stroke.

BACKGROUND AND PURPOSE: The iScore is a prediction tool originally developed to estimate the risk of death after hospitalization for an acute ischemic stroke. Our objective was to determine whether the iScore could also predict poor functional outcomes. METHODS: We applied the iScore to patients presenting with an acute ischemic stroke at multiple hospitals in Ontario, Canada, between 2003 and 2008, who had been identified from the Registry of the Canadian Stroke Network regional stroke center database (n=3818) and from an external data set, the Registry of the Canadian Stroke Network Ontario Stroke Audit (n=4635). Patients were excluded if they were included in the sample used to develop and validate the initial iScore. Poor functional outcomes were defined as: (1) death at 30 days or disability at discharge, in which disability was defined as having a modified Rankin Scale 3 to 5; and (2) death at 30 days or institutionalization at discharge. RESULTS: The prevalence of poor functional outcomes in the Registry of the Canadian Stroke Network and the Ontario Stroke Audit, respectively, were 55.7% and 44.1% for death at 30 days or disability at discharge and 16.9% and 16.2%, respectively, for death at 30 days or institutionalization at discharge. The iScore stratified the risk of poor outcomes in low- and high-risk individuals. Observed versus predicted outcomes showed high correlations: 0.988 and 0.940 for mortality or disability and 0.985 and 0.993 for mortality or institutionalization in the Registry of the Canadian Stroke Network and Ontario Stroke Audit cohorts. CONCLUSIONS: The iScore can be used to estimate the risk of death or a poor functional outcome after an acute ischemic stroke.

Narcotic analgesic utilization amongst injured workers: using concept mapping to understand current issues from the perspectives of physicians and pharmacists.

BACKGROUND: Work-related injuries result in considerable morbidity, as well as social and economic costs. Pain associated with these injuries is a complex, contested topic, and narcotic analgesics (NA) remain important treatment options. Factors contributing to NA utilization patterns are poorly understood. This qualitative study sought to characterize the factors contributing to NA utilization amongst injured workers from the perspectives of physicians and pharmacists. METHODS: The study employed concept mapping methodology, a structured process yielding a conceptual framework of participants' views on a particular topic. A visual display of the ideas/concepts generated is produced. Eligible physicians and pharmacists (n = 22) serving injured workers in the province of Ontario (Canada) were recruited via purposive sampling, and participated in concept mapping activities (consisting of brainstorming, sorting, rating, and map exploration). Participants identified factors influencing NA utilization, and sorted these factors into categories (clusters). Next, they rated the factors on two scales: 'strength of influence on NA over-utilization' and 'amenability to intervention'. During follow-up focus groups, participants refined the maps and discussed the findings and their implications. RESULTS: 82 factors were sorted into 7 clusters: addiction risks, psychosocial issues, social/work environment factors, systemic-third party factors, pharmacy-related factors, treatment problems, and physician factors. These clusters were grouped into 2 overarching categories/regions on the map: patient-level factors, and healthcare/compensation system-level factors. Participants rated NA over-utilization as most influenced by patient-level factors, while system-level factors were rated as most amenable to intervention. One system-level cluster was rated highly on both scales (treatment problems - e.g. poor continuity of care, poor interprofessional communication, lack of education/support for physicians regarding pain management, unavailability of multidisciplinary team-based care, prolonged wait times to see specialists). CONCLUSIONS: Participants depicted factors driving NA utilization among injured workers as complex. Patient-level factors were perceived as most influential on over-utilization, while system-level factors were considered most amenable to intervention. This has implications for intervention design, suggesting that systemic/structural factors should be taken into account in order to address this important health issue.

International Practice Variation in Weaning Critically Ill Adults from Invasive Mechanical Ventilation.

RATIONALE: Randomized trials and meta-analyses have informed several aspects of weaning. Results are rarely replicated in practice, as evidence is applied in intensive care units that differ from the settings in which it was generated. OBJECTIVES: We aimed to: 1) describe weaning practice variation (identifying weaning candidates, conducting spontaneous breathing trials, using ventilator modes, and other aspects of care during weaning); 2) characterize regional differences in weaning practices; and 3) identify factors associated with practice variation. METHODS: We conducted a cross-sectional, self-administered, international postal survey of adult intensivist members of regional critical care societies from six geographic regions, including Canada, India, the United Kingdom, Europe, Australia/New Zealand, and the United States. We worked with societies to randomly select potential respondents from membership lists and administer questionnaires with the goal of obtaining 200 responses per region. RESULTS: We analyzed 1,144 questionnaires (Canada, 156; India, 136; United Kingdom, 219; Europe, 260; Australia/New Zealand, 196; United States, 177). Across regions, most respondents screened patients once daily to identify spontaneous breathing trials candidates (regional range, 70.0%-95.6%) and less often screened twice daily (range, 12.2%-33.1%) or more than twice daily (range, 1.6%-18.2%). To wean patients, most respondents used pressure support alone (range, 31.0%-71.7%) or with spontaneous breathing trials (range, 35.7%-68.1%). To conduct spontaneous breathing trials, respondents predominantly used pressure support with positive end-expiratory pressure (range, 56.5%-72.3%) and T-piece (8.9%-59.5%). Across regions, we found important variation in screening frequency, spontaneous breathing trials techniques; ventilator modes, written directives to guide care, noninvasive ventilation; and the roles played by available personnel in various aspects of weaning. CONCLUSIONS: Our findings document the presence and extent of practice variation in ventilator weaning on an international scale, and highlight the multidisciplinary and collaborative nature of weaning.

MSH2 118T>C and MSH6 159C>T promoter polymorphisms and the risk of colorectal cancer.

The most important indicator of colorectal cancer (CRC) risk is the presence of family history of the disease. Inherited genetic changes, such as single nucleotide polymorphisms, in key candidate genes may contribute to CRC risk. We investigated whether promoter polymorphisms in DNA mismatch repair (MMR) genes MSH2 and MSH6 are associated with the risk of CRC. We genotyped 929 CRC patients and 1098 control subjects from Ontario, and 467 patients and 344 controls from Newfoundland and Labrador, for two promoter polymorphisms in the MMR genes MSH2 and MSH6 using the fluorogenic 5' nuclease assay. We used unconditional logistic regression to evaluate the association between each polymorphism and CRC after adjusting for age and sex. The associations between polymorphisms and tumor clinicopathological features were evaluated with a Pearson's chi-squared test or Fisher's exact test. All statistical tests were two sided. We observed strong associations between the MSH2 -118T>C polymorphism and family history of CRC based on the Amsterdam criteria I (P = 0.005) and Amsterdam criteria I and II (P = 0.036) among cases from Ontario. This association was especially evident among female CRC patients in Ontario (for Amsterdam criteria I, and I and II combined, P = 0.003 and P = 0.0001, respectively). The MSH2 -118T>C polymorphism was associated with strong family history of CRC in Ontario patients.

Tissue-specific modulation of glucocorticoid receptor expression in response to salinity acclimation in rainbow trout.

While studies clearly point to a role for cortisol signaling in seawater adaptation, very little is known about salinity impact on glucocorticoid receptor (GR) expression in fish. To this end, we investigated the temporal GR expression in the gill and liver of rainbow trout (Oncorhynchus mykiss) to salinity exposure. Trout were subjected to gradual salinity increases (11 ppt for 1 d, 17 ppt for 2 d and 23 ppt for 2 d) over a five day period. Gill Na(+), K(+)-ATPase alpha-subunit mRNA showed a transient elevation with salinity exposure, while gill cystic fibrosis transmembrane conductance regulator mRNA was not significantly affected by salinity. Liver PEPCK transcript levels showed a transient increase at day 1, but not at day 3 or day 5 of salinity exposure, while the activity of this enzyme was significantly depressed at all time points. Liver glycogen content was also significantly reduced by salinity exposure compared to the freshwater group. Gill GR transcript levels were 3-fold greater upon salinity exposure and this level was maintained over the 5 day period, while gill GR protein content remained unchanged except for a significant drop at day 1 of salinity exposure. Liver GR transcript levels showed no significant change with salinity exposure, while GR protein content was transiently elevated at day 3, but not at day 1 or day 5 of salinity exposure. The tissue-specific GR transcript response in the gill leads us to hypothesize a role for osmosensory signal transduction pathway in the regulation of GR expression in fish. Collectively, salinity exposure modulates GR expression and glucocorticoid signaling in rainbow trout.

Aversion to ambiguity and willingness to take risks affect therapeutic decisions in managing atrial fibrillation for stroke prevention: results of a pilot study in family physicians.

BACKGROUND: Anticoagulation is the therapeutic paradigm for stroke prevention in patients with atrial fibrillation (AF). It is unknown how physicians make treatment decisions in primary stroke prevention for patients with AF. OBJECTIVES: To evaluate the association between family physicians' risk preferences (aversion risk and ambiguity) and therapeutic recommendations (anticoagulation) in the management of AF for primary stroke prevention by applying concepts from behavioral economics. METHODS: Overall, 73 family physicians participated and completed the study. Our study comprised seven simulated case vignettes, three behavioral experiments, and two validated surveys. Behavioral experiments and surveys incorporated an economic framework to determine risk preferences and biases (e.g., ambiguity aversion, willingness to take risks). The primary outcome was making the correct decision of anticoagulation therapy. Secondary outcomes included medical errors in the management of AF for stroke prevention. RESULTS: Overall, 23.3% (17/73) of the family physicians elected not to escalate the therapy from antiplatelets to anticoagulation when recommended by best practice guidelines. A total of 67.1% of physicians selected the correct therapeutic options in two or more of the three simulated case vignettes. Multivariate analysis showed that aversion to ambiguity was associated with appropriate change to anticoagulation therapy in the management of AF (OR 5.48, 95% CI 1.08-27.85). Physicians' willingness to take individual risk in multiple domains was associated with lower errors (OR 0.16, 95% CI 0.03-0.86). CONCLUSION: Physicians' aversion to ambiguity and willingness to take risks are associated with appropriate therapeutic decisions in the management of AF for primary stroke prevention. Further large scale studies are needed.

Genetic instability in human tumors.

Genetic, or genomic, instability refers to a series of observed spontaneous genetic changes occurring at an accelerated rate in cell populations derived from the same ancestral precursor. This is far from a new finding, but is one that has increasingly gained more attention in the last decade due to its plausible role(s) in tumorigenesis. The majority of genetic alterations contributing to the malignant transformation are seen in growth regulatory genes, and in genes involved in cell cycle progression and arrest. Genomic instability may present itself through alterations in the length of short repeat stretches of coding and non-coding DNA, resulting in microsatellite instability. Tumors with such profiles are referred to as exhibiting a mutator phenotype, which is largely a consequence of inactivating mutations in DNA damage repair genes. Genomic instability may also, and most commonly, results from gross chromosomal changes, such as translocations or amplifications, which lead to chromosomal instability. Telomere length and telomerase activity, important in maintaining chromosomal structure and in regulating a normal cell's lifespan, have been shown to have a function in both suppressing and facilitating malignant transformation. In addition to such direct sequence and structural changes, gene silencing through the hypermethylation of promoter regions, or increased gene expression through the hypomethylation of such regions, together, form an alternative, epigenetic mechanism leading to instability. Emerging evidence also suggests that dietary and environmental agents can further modulate the contribution of genetic instability to tumorigenesis. Currently, there is still much debate over the distinct classes of genomic instability and their specific roles in the initiation of tumor formation, as well as in the progressive transition to a cancerous state. This review examines the various molecular mechanisms that result in this genomic instability and the potential contribution of the latter to human carcinogenesis.

JURaSSiC: accuracy of clinician vs risk score prediction of ischemic stroke outcomes.

OBJECTIVE: We compared the accuracy of clinicians and a risk score (iScore) to predict observed outcomes following an acute ischemic stroke. METHODS: The JURaSSiC (Clinician JUdgment vs Risk Score to predict Stroke outComes) study assigned 111 clinicians with expertise in acute stroke care to predict the probability of outcomes of 5 ischemic stroke case scenarios. Cases (n = 1,415) were selected as being representative of the 10 most common clinical presentations from a pool of more than 12,000 stroke patients admitted to 12 stroke centers. The primary outcome was prediction of death or disability (modified Rankin Scale [mRS] ≥3) at discharge within the 95% confidence interval (CI) of observed outcomes. Secondary outcomes included 30-day mortality and death or institutionalization at discharge. RESULTS: Clinicians made 1,661 predictions with overall accuracy of 16.9% for death or disability at discharge, 46.9% for 30-day mortality, and 33.1% for death or institutionalization at discharge. In contrast, 90% of the iScore-based estimates were within the 95% CI of observed outcomes. Nearly half (n = 53 of 111; 48%) of participants were unable to accurately predict the probability of the primary outcome in any of the 5 rated cases. Less than 1% (n = 1) provided accurate predictions in 4 of the 5 cases and none accurately predicted all 5 case outcomes. In multivariable analyses, the presence of patient characteristics associated with poor outcomes (mRS ≥3 or death) in previous studies (older age, high NIH Stroke Scale score, and nonlacunar subtype) were associated with more accurate clinician predictions of death at 30 days (odds ratio [OR] 2.40, 95% CI 1.57-3.67) and with a trend for more accurate predictions of death or disability at discharge (OR 1.85, 95% CI 0.99-3.46). CONCLUSIONS: Clinicians with expertise in stroke performed poorly compared to a validated tool in predicting the outcomes of patients with an acute ischemic stroke. Use of the risk stroke outcome tool may be superior for decision-making following an acute ischemic stroke.

Is pre-existing dementia an independent predictor of outcome after stroke? A propensity score-matched analysis.

With an aging population, patients are increasingly likely to present with stroke and pre-existing dementia, which may lead to greater death and disability. The aim of this work was to assess the risk of all-cause mortality and poor functional outcomes after ischemic stroke in patients with and without pre-existing dementia. We conducted a multicenter cohort study of all patients presenting to 12 tertiary care institutions participating in the Registry of the Canadian Stroke Network (RCSN) with a first ischemic stroke between 2003 and 2008. Individuals with pre-existing dementia were matched using propensity-score methods with patients without dementia during their index hospitalization based on the following characteristics: age (within 3 years), sex, stroke severity, stroke subtype (lacunar vs. non-lacunar), level of consciousness, vascular risk factors, dysphagia, glucose and creatinine on admission, Charlson index, residence prior to hospitalization (home vs. other), pre-admission dependency, hospital arrival via ambulance, admission to stroke unit, thrombolysis, and palliative care. A propensity score for all-cause mortality and clinical outcomes was developed. Registry of the Canadian Stroke Network (RCSN) and Registered Persons Database (RPDB). The primary outcome was all-cause mortality at 30 days. Secondary outcomes included mortality at discharge and at 1 year, disability at discharge (modified Rankin scale ≥ 3), medical complications (pneumonia), and discharge disposition. A subgroup analysis assessing the risk of intracerebral hemorrhage among those receiving thrombolysis was also conducted. We matched 877 patients with an acute ischemic stroke and pre-existing dementia to 877 stroke patients without dementia. Patients were well matched. The mean age was 82 years and 58 % were women. Mortality at discharge, 30 days, and 1 year after stroke was similar in patients with and without dementia [for mortality at discharge RR 0.88 [95 % confidence interval (CI) 0.74-1.05]; mortality at 30-days: RR 0.88 (95 % CI 0.75-1.03) and mortality at 1 year: RR 1.01 (95 % CI 0.92-1.11). Patients with pre-existing dementia had similar disability at discharge and home disposition. In the subgroup of patients who received thrombolysis, there were no differences between those with and without dementia in the risk of intracerebral hemorrhage (RR 1.27; 95 % CI 0.69-2.35) and no differences in mortality or disability at discharge. Pre-existing dementia is not independently associated with mortality, disability, or institutionalization after ischemic stroke. Pre-existing dementia may not necessarily preclude access to thrombolytic therapy and specialized stroke care.

Specific variants in the MLH1 gene region may drive DNA methylation, loss of protein expression, and MSI-H colorectal cancer.

BACKGROUND: We previously identified an association between a mismatch repair gene, MLH1, promoter SNP (rs1800734) and microsatellite unstable (MSI-H) colorectal cancers (CRCs) in two samples. The current study expanded on this finding as we explored the genetic basis of DNA methylation in this region of chromosome 3. We hypothesized that specific polymorphisms in the MLH1 gene region predispose it to DNA methylation, resulting in the loss of MLH1 gene expression, mismatch-repair function, and consequently to genome-wide microsatellite instability. METHODOLOGY/PRINCIPAL FINDINGS: We first tested our hypothesis in one sample from Ontario (901 cases, 1,097 controls) and replicated major findings in two additional samples from Newfoundland and Labrador (479 cases, 336 controls) and from Seattle (591 cases, 629 controls). Logistic regression was used to test for association between SNPs in the region of MLH1 and CRC, MSI-H CRC, MLH1 gene expression in CRC, and DNA methylation in CRC. The association between rs1800734 and MSI-H CRCs, previously reported in Ontario and Newfoundland, was replicated in the Seattle sample. Two additional SNPs, in strong linkage disequilibrium with rs1800734, showed strong associations with MLH1 promoter methylation, loss of MLH1 protein, and MSI-H CRC in all three samples. The logistic regression model of MSI-H CRC that included MLH1-promoter-methylation status and MLH1 immunohistochemistry status fit most parsimoniously in all three samples combined. When rs1800734 was added to this model, its effect was not statistically significant (P-value  = 0.72 vs. 2.3×10(-4) when the SNP was examined alone). CONCLUSIONS/SIGNIFICANCE: The observed association of rs1800734 with MSI-H CRC occurs through its effect on the MLH1 promoter methylation, MLH1 IHC deficiency, or both.

MLH1 -93G>A promoter polymorphism and the risk of microsatellite-unstable colorectal cancer.

BACKGROUND: Although up to 30% of patients with colorectal cancer have a positive family history of colorectal neoplasia, few colorectal cancers can be explained by mutations in high-penetrance genes. We investigated whether polymorphisms in DNA mismatch repair genes are associated with the risk of colorectal cancer. METHODS: We genotyped 929 case patients and 1098 control subjects from Ontario and 430 case patients and 275 control subjects from Newfoundland and Labrador for five polymorphisms in the mismatch repair genes MLH1 and MSH2 with the fluorogenic 5' nuclease assay. Tumor microsatellite instability (MSI) was determined with a polymerase chain reaction-based method; MSI status was assigned as high (MSI-H, > or = 30% unstable markers among all markers tested), low (MSI-L, <30% markers unstable), or stable (MSS, no unstable markers). We used unconditional logistic regression to evaluate the association between each polymorphism and colorectal cancer after adjusting for age and sex. The associations between polymorphisms and tumor clinicopathologic features were evaluated with a Pearson's chi-square or Fisher's exact test. All statistical tests were two-sided. RESULTS: We observed strong associations between the MLH1 -93G>A polymorphism and MSI-H tumors among case patients from Ontario (P = .001) and Newfoundland (P = .003). When compared with the control populations, homozygosity for the MLH1 -93G>A variant allele was associated with MSI-H tumors among case patients in Ontario (adjusted odds ratio [OR] = 3.23, 95% confidence interval [CI] = 1.65 to 6.30) and in Newfoundland (OR = 8.88, 95% CI = 2.33 to 33.9), as was heterozygosity among case patients in Ontario (OR = 1.84, 95% CI = 1.20 to 2.83) and in Newfoundland (OR = 2.56, 95% CI = 1.14 to 5.75). Genotype frequencies were similar among case patients with MSS and MSI-L tumors and control subjects, and the majority of homozygous variant carriers had MSS tumors. Among case patients from Ontario, an association between the MLH1 -93G>A polymorphism and a strong family history of colorectal cancer (for Amsterdam criteria I and II, P = .004 and P = .02, respectively) was observed. CONCLUSION: In two patient populations, the MLH1 -93G>A polymorphism was associated with an increased risk of MSI-H colorectal cancer.

Cortisol treatment affects glucocorticoid receptor and glucocorticoid-responsive genes in the liver of rainbow trout.

We investigated whether longer-term cortisol exposure modified hepatic glucocorticoid receptor (GR) status and tissue responsiveness to cortisol stimulation in rainbow trout. Fish were given intraperitoneal implants of cortisol (50mg/kg body mass) and this led to elevated plasma cortisol levels mimicking chronically stressed salmonids. There was significantly higher hepatic GR mRNA abundance, despite a drop in GR protein content in the liver of cortisol-treated fish. The tissue responsiveness to cortisol stimulation was apparent from the higher plasma glucose concentration and liver glycogen content. Also, the higher phosphoenolpyruvate carboxykinase (PEPCK) mRNA abundance, a key glucocorticoid-responsive gene, by cortisol suggests activation of the GR signalling pathway. There was no significant effect of cortisol treatment on liver PEPCK, alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase activities compared to the sham fish. The higher heat shock protein (hsp) 90 mRNA abundance and a corresponding elevation in this protein and constitutive hsp70 (hsc70) protein content in the cortisol-treated fish reflects a role for glucocorticoids in the hepatic stress response process. Taken together, the molecular and biochemical responses evident in the liver of trout imply changes favouring tissue responsiveness to glucocorticoids and may be a mechanism to offset GR protein downregulation evident with chronic cortisol stimulation in rainbow trout.