117 resultados para Chi-squared distribution

em Université de Lausanne, Switzerland


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BACKGROUND: Hypovitaminosis D is well known in different populations, but may be under diagnosed in certain populations. We aim to determine the first diagnosis considered, the duration and resolution of symptoms, and the predictors of response to treatment in female asylum seekers suffering from hypovitaminosis D. METHODS: Design: A pre- and post-intervention observational study. Setting: A network comprising an academic primary care centre and nurse practitioners. Participants: Consecutive records of 33 female asylum seekers with complaints compatible with osteomalacia and with hypovitaminosis D (serum 25-(OH) vitamin D < 21 nmol/l). Treatment intervention: The patients received either two doses of 300,000 IU intramuscular cholecalciferol as well as 800 IU of cholecalciferol with 1000 mg of calcium orally, or the oral treatment only. Main outcome measures: We recorded the first diagnosis made by the physicians before the correct diagnosis of hypovitaminosis D, the duration of symptoms before diagnosis, the responders and non-responders to treatment, the duration of symptoms after treatment, and the number of medical visits and analgesic drugs prescribed 6 months before and 6 months after diagnosis. Tests: Two-sample t-tests, chi-squared tests, and logistic regression analyses were performed. Analyses were performed using SPSS 10.0. RESULTS: Prior to the discovery of hypovitaminosis D, diagnoses related to somatisation were evoked in 30 patients (90.9%). The mean duration of symptoms before diagnosis was 2.53 years (SD 3.20). Twenty-two patients (66.7%) responded completely to treatment; the remaining patients were considered to be non-responders. After treatment was initiated, the responders' symptoms disappeared completely after 2.84 months. The mean number of emergency medical visits fell from 0.88 (SD 1.08) six months before diagnosis to 0.39 (SD 0.83) after (P = 0.027). The mean number of analgesic drugs that were prescribed also decreased from 1.67 (SD 1.5) to 0.85 (SD 1) (P = 0.001). CONCLUSION: Hypovitaminosis D in female asylum seekers may remain undiagnosed, with a prolonged duration of chronic symptoms. The potential pitfall is a diagnosis of somatisation. Treatment leads to a rapid resolution of symptoms, a reduction in the use of medical services, and the prescription of analgesic drugs in this vulnerable population.

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Swain corrects the chi-square overidentification test (i.e., likelihood ratio test of fit) for structural equation models whethr with or without latent variables. The chi-square statistic is asymptotically correct; however, it does not behave as expected in small samples and/or when the model is complex (cf. Herzog, Boomsma, & Reinecke, 2007). Thus, particularly in situations where the ratio of sample size (n) to the number of parameters estimated (p) is relatively small (i.e., the p to n ratio is large), the chi-square test will tend to overreject correctly specified models. To obtain a closer approximation to the distribution of the chi-square statistic, Swain (1975) developed a correction; this scaling factor, which converges to 1 asymptotically, is multiplied with the chi-square statistic. The correction better approximates the chi-square distribution resulting in more appropriate Type 1 reject error rates (see Herzog & Boomsma, 2009; Herzog, et al., 2007).

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Many effects of nitric oxide (NO) are mediated by the activation of guanylyl cyclases and subsequent production of the second messenger cyclic guanosine-3',5'-monophosphate (cGMP). cGMP activates cGMP-dependent protein kinases (PRKGs), which can therefore be considered downstream effectors of NO signaling. Since NO is thought to be involved in the regulation of both sleep and circadian rhythms, we analyzed these two processes in mice deficient for cGMP-dependent protein kinase type I (PRKG1) in the brain. Prkg1 mutant mice showed a strikingly altered distribution of sleep and wakefulness over the 24 hours of a day as well as reductions in rapid-eye-movement sleep (REMS) duration and in non-REM sleep (NREMS) consolidation, and their ability to sustain waking episodes was compromised. Furthermore, they displayed a drastic decrease in electroencephalogram (EEG) power in the delta frequency range (1-4 Hz) under baseline conditions, which could be normalized after sleep deprivation. In line with the re-distribution of sleep and wakefulness, the analysis of wheel-running and drinking activity revealed more rest bouts during the activity phase and a higher percentage of daytime activity in mutant animals. No changes were observed in internal period length and phase-shifting properties of the circadian clock while chi-squared periodogram amplitude was significantly reduced, hinting at a less robust oscillator. These results indicate that PRKG1 might be involved in the stabilization and output strength of the circadian oscillator in mice. Moreover, PRKG1 deficiency results in an aberrant pattern, and consequently a reduced quality, of sleep and wakefulness, possibly due to a decreased wake-promoting output of the circadian system impinging upon sleep.

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β-Arrestin2 (ARRB2) is a component of the G-protein-coupled receptor complex and is involved in μ-opioid and dopamine D(2) receptor signaling, two central processes in methadone signal transduction. We analyzed 238 patients in methadone maintenance treatment (MMT) and identified a haplotype block (rs34230287, rs3786047, rs1045280 and rs2036657) spanning almost the entire ARRB2 locus. Although none of these single nucleotide polymorphisms (SNPs) leads to a change in amino-acid sequence, we found that for all the SNPs analyzed, with exception of rs34230287, homozygosity for the variant allele confers a nonresponding phenotype (n=73; rs1045280C and rs2036657G: OR=3.1, 95% CI=1.5-6.3, P=0.004; rs3786047A: OR=2.5, 95% CI=1.2-5.1, P=0.02) also illustrated by a 12-fold shorter period of negative urine screening (P=0.01). The ARRB2 genotype may thus contribute to the interindividual variability in the response to MMT and help to predict response to treatment.

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BACKGROUND: To evaluate the effect of statins on the annual expansion rate (ER) of small infrarenal abdominal aortic aneurysms (AAA). PATIENTS AND METHODS: All patients under regular surveillance for small AAA between January 2000 and September 2007, in the Department of Angiology, Lausanne University Hospital, were included. Inclusion criteria were baseline abdominal aortic diameter between 25 and 55 mm, at least two measurements of AAA diameter and a minimum follow up of 6 months. Patients with Marfan disease, infectious or inflammatory AAA, and patients with prior AAA repair were excluded. The influence of statin use and other factors on ER were examined by bivariate and multivariate analysis. RESULTS: Among 589 patients who underwent an abdominal aorta evaluation, 94 patients (89 % men, mean age 69.1 years) were finally included in the analysis. Baseline AAA size was 39.9 ± 7.7 mm (mean±SE) and 48.7 ± 8.4 mm at end of follow-up. Patients had a regular aneurysm size assessment during 38.5 ± 27.7 months. Mean ER was 3.59 mm/y (± 2.81). The 50 patients who were treated with statin during the study period had a lower ER compared to the 44 controls (2.91 vs 4.37 mm/year, p = 0.01). CONCLUSIONS: This study confirms the considerable individual variations in the AAA expansion rate, and emphasizes the need for regular aortic diameter assessments. In this study, patients treated with statin demonstrate a significant decrease in the ER compared to controls. This finding need to be evaluated in prospective interventional studies powered to demonstrate the potential benefit of statin treatment.

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BACKGROUND AND STUDY AIMS: Various screening methods for colorectal cancer (CRC) are promoted by professional societies; however, few data are available about the factors that determine patient participation in screening, which is crucial to the success of population-based programs. This study aimed (i) to identify factors that determine acceptance of screening and preference of screening method, and (ii) to evaluate procedure success, detection of colorectal neoplasia, and patient satisfaction with screening colonoscopy. PATIENTS AND METHODS: Following a public awareness campaign, the population aged 50 - 80 years was offered CRC screening in the form of annual fecal occult blood tests, flexible sigmoidoscopy, a combination of both, or colonoscopy. RESULTS: 2731 asymptomatic persons (12.0 % of the target population) registered with and were eligible to take part in the screening program. Access to information and a positive attitude to screening were major determinants of participation. Colonoscopy was the method preferred by 74.8 % of participants. Advanced colorectal neoplasia was present in 8.5 %; its prevalence was higher in males and increased with age. Significant complications occurred in 0.5 % of those undergoing colonoscopy and were associated with polypectomy or sedation. Most patients were satisfied with colonoscopy and over 90 % would choose it again for CRC screening. CONCLUSIONS: In this population-based study, only a small proportion of the target population underwent CRC screening despite an extensive information campaign. Colonoscopy was the preferred method and was safe. The determinants of participation in screening and preference of screening method, together with the distribution of colorectal neoplasia in different demographic categories, provide a rationale for improving screening procedures.

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PURPOSE: The aim of this study was to determine whether tumor location proximal or distal to the splenic flexure is associated with distinct molecular patterns and can predict clinical outcome in a homogeneous group of patients with Dukes B (T3-T4, N0, M0) colorectal cancer. It has been hypothesized that proximal and distal colorectal cancer may arise through different pathogenetic mechanisms. Although p53 and Ki-ras gene mutations occur frequently in distal tumors, another form of genomic instability associated with defective DNA mismatch repair has been predominantly identified in the proximal colon. To date, however, the clinical usefulness of these molecular characteristics remains unproven. METHODS: A total of 126 patients with a lymph node-negative sporadic colon or rectum adenocarcinoma were prospectively assessed with the endpoint of death by cancer. No patient received either radiotherapy or chemotherapy. p53 protein was studied by immunohistochemistry using DO-7 monoclonal antibody, and p53 and Ki-ras gene mutations were detected by single strand conformation polymorphism assay. RESULTS: During a mean follow-up of 67 months, the overall five-year survival was 70 percent. Nuclear p53 staining was found in 57 tumors (47 percent), and was more frequent in distal than in proximal tumors (55 vs. 21 percent; chi-squared test, P < 0.001). For the whole group, p53 protein expression correlated with poor survival in univariate and multivariate analysis (log-rank test, P = 0.01; hazard ratio = 2.16; 95 percent confidence interval = 1.12-4.11, P = 0.02). Distal colon tumors and rectal tumors exhibited similar molecular patterns and showed no difference in clinical outcome. In comparison with distal colorectal cancer, proximal tumors were found to be statistically significantly different on the following factors: mucinous content (P = 0.008), degree of histologic differentiation (P = 0.012), p53 protein expression, and gene mutation (P = 0.001 and 0.01 respectively). Finally, patients with proximal tumors had a marginally better survival than those with distal colon or rectal cancers (log-rank test, P = 0.045). CONCLUSION: In this series of Dukes B colorectal cancers, p53 protein expression was an independent factor for survival, which also correlated with tumor location. Eighty-six percent of p53-positive tumors were located in the distal colon and rectum. Distal colon and rectum tumors had similar molecular and clinical characteristics. In contrast, proximal neoplasms seem to represent a distinct entity, with specific histopathologic characteristics, molecular patterns, and clinical outcome. Location of the neoplasm in reference to the splenic flexure should be considered before group stratification in future trials of adjuvant chemotherapy in patients with Dukes B tumors.

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Alcohol-dependent subjects tend to report lower level of response to alcohol (LR) in the years before the disorder developed, compared to control subjects. The Self-Rating of the Effects of alcohol (SRE) score is a quick and valid retrospective estimate of LR. This study examined the associations between alcohol abuse or dependence and early experience of alcohol as measured on retrospective SRE score (relating to the first five times alcohol was imbibed), and the presence of alcohol abuse or dependence, in patients attending primary care. Higher Early SRE score (i.e. greater early tolerance of alcohol) was obtained in patients with an alcohol-related diagnosis than in patients without those diagnoses. Using a cut-off of 2 on the Early SRE score, the Early SRE score could discriminate between patients with and without an alcohol diagnosis with moderate to high sensitivity (84%) and modest specificity (57%).

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PURPOSE: Health benefits of sport and exercise are well documented in children, adolescents and adults, but little is known about emerging adulthood-a period of life characterized by significant demographic and developmental changes. The present study aimed to assess the health impact of changes in sport and exercise levels during that specific period of life. METHODS: The analysis used baseline and 15-month follow-up data (N = 4,846) from the cohort study on substance use risk factors. Associations between baseline exercise levels or changes in exercise levels and health indicators (i.e., health-related quality of life, depression, body mass index, alcohol dependence, nicotine dependence and cannabis use disorder) were measured using chi-squared tests and ANOVA. Direction of effects was tested using cross-lagged analysis. RESULTS: At baseline, all health indicator scores were observed to be better for regular exercisers than for other exercise levels. At follow-up, participants who had maintained regular exercise over time had better scores than those who had remained irregular exercisers or had discontinued, but their scores for health-related quality of life and depression were close to those of participants who had adopted regular exercise after the baseline questionnaire. Cross-lagged analysis indicated that regular exercise at baseline was a significant predictor of health-related quality of life and substance use dependence at follow-up, but was itself predicted only by health-related quality of life. CONCLUSIONS: From a health promotion perspective, this study emphasizes how important it is for emerging adult men to maintain, or adopt, regular sport and exercise.

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The purpose of this study was to prospectively compare free-breathing navigator-gated cardiac-triggered three-dimensional steady-state free precession (SSFP) spin-labeling coronary magnetic resonance (MR) angiography performed by using Cartesian k-space sampling with that performed by using radial k-space sampling. A new dedicated placement of the two-dimensional selective labeling pulse and an individually adjusted labeling delay time approved by the institutional review board were used. In 14 volunteers (eight men, six women; mean age, 28.8 years) who gave informed consent, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), vessel sharpness, vessel length, and subjective image quality were investigated. Differences between groups were analyzed with nonparametric tests (Wilcoxon, Pearson chi2). Radial imaging, as compared with Cartesian imaging, resulted in a significant reduction in the severity of motion artifacts, as well as an increase in SNR (26.9 vs 12.0, P < .05) in the coronary arteries and CNR (23.1 vs 8.8, P < .05) between the coronary arteries and the myocardium. A tendency toward improved vessel sharpness and vessel length was also found with radial imaging. Radial SSFP imaging is a promising technique for spin-labeling coronary MR angiography.

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PURPOSE: To determine the diagnostic value of the intravascular contrast agent gadocoletic acid (B-22956) in three-dimensional, free breathing coronary magnetic resonance angiography (MRA) for stenosis detection in patients with suspected or known coronary artery disease. METHODS: Eighteen patients underwent three-dimensional, free breathing coronary MRA of the left and right coronary system before and after intravenous application of a single dose of gadocoletic acid (B-22956) using three different dose regimens (group A 0.050 mmol/kg; group B 0.075 mmol/kg; group C 0.100 mmol/kg). Precontrast scanning followed a coronary MRA standard non-contrast T2 preparation/turbo-gradient echo sequence (T2Prep); for postcontrast scanning an inversion-recovery gradient echo sequence was used (real-time navigator correction for both scans). In pre- and postcontrast scans quantitative analysis of coronary MRA data was performed to determine the number of visible side branches, vessel length and vessel sharpness of each of the three coronary arteries (LAD, LCX, RCA). The number of assessable coronary artery segments was determined to calculate sensitivity and specificity for detection of stenosis > or = 50% on a segment-to-segment basis (16-segment-model) in pre- and postcontrast scans with x-ray coronary angiography as the standard of reference. RESULTS: Dose group B (0.075 mmol/kg) was preferable with regard to improvement of MR angiographic parameters: in postcontrast scans all MR angiographic parameters increased significantly except for the number of visible side branches of the left circumflex artery. In addition, assessability of coronary artery segments significantly improved postcontrast in this dose group (67 versus 88%, p < 0.01). Diagnostic performance (sensitivity, specificity, accuracy) was 83, 77 and 78% for precontrast and 86, 95 and 94% for postcontrast scans. CONCLUSIONS: The use of gadocoletic acid (B-22956) results in an improvement of MR angiographic parameters, asssessability of coronary segments and detection of coronary stenoses > or = 50%.

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Little information exists regarding the effect of several obesity markers on blood pressure (BP) levels in youth. Transverse study including 2494 boys and 2589 girls. Height, weight and waist were measured according to the international criteria and body fat (BF) by bioimpedance. BP was measured by an automated device. Hypertension was defined using sex-specific, age-specific and height-specific observation-points. Body mass index (BMI) and waist were positively related with systolic blood pressure (SBP) and diastolic blood pressure (DBP) and heart rate in both sexes, whereas the relationships with BF were less consistent. Stepwise linear regression analysis showed that BMI was positively related with SBP and DBP in both sexes, whereas BF was negatively related with SBP in both sexes and with heart rate in boys only; finally, waist was positively related with SBP in boys and heart rate in girls. Age and heart rate-adjusted values of SBP and DBP increased with BMI: for SBP, 117+/-1, 123+/-1 and 124+/-1 mmHg in normal, overweight and obese boys, respectively; corresponding values for girls were 111+/-1, 114+/-1 and 116+/-2 mmHg (mean+/-SE, P<0.001). Overweight and obese boys had an odds ratio for being hypertensive of 2.26 (95% confidence interval: 1.79-2.86) and 3.36 (2.32-4.87), respectively; corresponding values for girls were 1.58 (confidence interval 1.25-1.99) and 2.31 (1.53-3.50). BMI, not BF or waist, is consistently and independently related to BP levels in children; overweight and obesity considerably increase the risk of hypertension.

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BACKGROUND AND OBJECTIVES: The suprascapular nerve (SSN) block is frequently performed for different shoulder pain conditions and for perioperative and postoperative pain control after shoulder surgery. Blind and image-guided techniques have been described, all of which target the nerve within the supraspinous fossa or at the suprascapular notch. This classic target point is not always ideal when ultrasound (US) is used because it is located deep under the muscles, and hence the nerve is not always visible. Blocking the nerve in the supraclavicular region, where it passes underneath the omohyoid muscle, could be an attractive alternative. METHODS: In the first step, 60 volunteers were scanned with US, both in the supraclavicular and the classic target area. The visibility of the SSN in both regions was compared. In the second step, 20 needles were placed into or immediately next to the SSN in the supraclavicular region of 10 cadavers. The accuracy of needle placement was determined by injection of dye and following dissection. RESULTS: In the supraclavicular region of volunteers, the nerve was identified in 81% of examinations (95% confidence interval [CI], 74%-88%) and located at a median depth of 8 mm (interquartile range, 6-9 mm). Near the suprascapular notch (supraspinous fossa), the nerve was unambiguously identified in 36% of examinations (95% CI, 28%-44%) (P < 0.001) and located at a median depth of 35 mm (interquartile range, 31-38 mm; P < 0.001). In the cadaver investigation, the rate of correct needle placement of the supraclavicular approach was 95% (95% CI, 86%-100%). CONCLUSIONS: Visualization of the SSN with US is better in the supraclavicular region as compared with the supraspinous fossa. The anatomic dissections confirmed that our novel supraclavicular SSN block technique is accurate.

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This randomized study compares the coronary perfusion rate in patients with acute myocardial infarction (AMI) treated with 2 different intravenous thrombolytic agents: streptokinase 1.5 million U given over 60 minutes and anisoylated human plasminogen streptokinase activator complex (anistreplase) administrated as a bolus of 30 U over 5 minutes. One hundred seventy-five patients (149 men and 26 women, mean age 54 years) have been included in this study. Eighty-nine patients were treated with anistreplase and 86 patients with streptokinase. AMI was inferior in 54 patients (61%) in the anistreplase group and in 54 patients (63%) in the streptokinase group. It was anterior in 35 (40%) and 32 (37%) patients, respectively. Coronary angiography and ventriculography were performed at a mean time (+/- SEM) of 207 +/- 11 minutes after the beginning of thrombolysis in 170 patients. A perfusion score grade of 2 or 3 according to the Thrombolysis in Myocardial Infarction trial was found in 63 patients (72%) in the anistreplase group and in 56 patients (68%) in the streptokinase group (p = NS). Severe bleeding occurred in 7 patients (8%) after anistreplase and in 6 patients (7%) after streptokinase. No cerebral hemorrhage occurred. Nine patients (5%) died during their hospital stay: 6 after anistreplase and 3 after streptokinase. It is concluded that intravenous administration of anistreplase or streptokinase is efficient and safe. Coronary patency 207 minutes after fibrinolysis, incidence of adverse events and mortality are similar in both groups.