Ridge regression dealswith collinearity in the homoscedastic linear regression model. When the number of predictors (p) is much larger than the number of observations (n), it gives unique ...least-square estimators. From both, classical and Bayesian approaches, parameter estimation is a highly demanding computational task, in the first one being an optimization problem and in the second one a high-dimensional integration problem usually faced up through Markov chain Monte Carlo (MCMC). The main drawback of MCMC is the practical impossibility of checking convergence to the posterior distribution, which is commonly very slow due to the large number of regression parameters. Here, a computational algorithm is proposed to obtain posterior estimates of regression parameters, variance components and predictions for the conventional ridge regression model. The algorithm is based on a reparametrization of the model which allows us to obtain the marginal posterior means and variances by integrating out a nuisance parameter whose marginal posterior is defined on the open interval
.
Abstract only
The antioxidant properties of Mexican traditional foods may contribute to reduce diseases caused by an increase in free radicals and reactive species such as diabetes and obesity in ...Mexican population.The purpose of this study was to investigate the properties of chocolate, vanilla and nopal. Antioxidant activity, reactive species and polyphenolic content were measured by fluorometric and spectrophotometric assays. Content of vitamin C was measured by titration and antioxidant activity
in vivo
of vanilla was measured in plasma of healthy subjects. The results demonstrated that vanilla, nopal and handmade Mexican chocolate have higher antioxidant activity than German, Swiss chocolate and blackberry. Mexican chocolate scavenges with higher affinity OH
.
> O2
.‐
> ONOO‐ > HOCl, whereas, vanilla is a better scavenger of H
2
O
2
> OH
.
> HOCl. Nopal contains approximately 280 mg of vitamin C/100 g of serving, higher than guavas and orange juice, however the content of Vitamin C as well as polyphenolic content decreases as the cooking time increases. Interestingly steamed nopal contains more polyphenols than raw nopal. Finally antioxidant activity in vanilla is transferred to the human plasma after 1 hour of consumption. Thus, these results suggest that the consumption of Mexican traditional foods can help to maintain the equilibrium between reactive species formation and the antioxidant capacity produced by the consumption of foods rich in antioxidants.
Purpose
The purpose of the study was to analyze whether the thyroid-stimulating hormone (TSH) alone avoids tests to exclude malignancy in all patients with functional thyroid nodules (FTN).
Methods
...Sixty-nine patients with FTN on
99m
Tc scintigraphy, radioiodine uptake test (RIU),
99m
Tc thyroid uptake, TSH assay, T3, and T4 obtained within 48 h were retrospectively identified out of 2,356 thyroid scans performed from January 2000 to April 2007. FTNs were classified as causing total, partial, or no inhibition of the thyroid as group 1, 2, or 3, respectively.
Results
TSH was subnormal in 21 of 69 (30.43%) patients. In group 1 (
N
= 23, 33.3%), TSH was subnormal, normal, and high in eight, nine, and six patients; in group 2 (
N
= 17, 24.6%), TSH was subnormal, normal, and high in four, six, and seven patients, and in group 3 (
N
= 29, 42%), TSH was subnormal, normal, and high in 9, 13, and 7 patients, respectively. TSH was significantly lower in group 1. In T3, T4,
99m
Tc thyroid uptake, and RIU, there were no differences between the three groups.
Conclusions
Only 30.43% of patients had subnormal TSH. TSH alone cannot avoid tests to exclude malignancy in all patients with FTN. FTN existence can only be accurately assessed by thyroid scintigraphy. The current incidence of FTN may be unknown because scintigraphy is not routinely performed in all patients with thyroid nodules. Thyroid scintigraphy of patients with high TSH can detect diseases such as Hashimoto’s thyroiditis and identify patients with FTN in whom no further diagnostic procedures would be needed in patients with normal TSH levels with nondiagnostic fine-needle aspiration results.
BACKGROUNDThis study evaluates the American Thyroid Association (ATA) ultrasound (US) classification system for the initial assessment of thyroid nodules to determine if it indeed facilitates ...clinical decision-making. AIMTo perform a systematic review and meta-analysis of the diagnostic value of the ATA US classification system for the initial assessment of thyroid nodules. METHODSIn accordance with the PRISMA statement for diagnostic test accuracy, we selected articles that evaluated the 2015 ATA US pattern guidelines using a diagnostic gold standard. We analyzed these cases using traditional diagnostic parameters, as well as the threshold approach to clinical decision-making and decision curve analysis. RESULTSWe reviewed 13 articles with 8445 thyroid nodules, which were classified according to 2015 ATA patterns. Of these, 46.62% were malignant. No cancer was found in any of the ATA benign pattern nodules. The Bayesian analysis post-test probability for cancer in each classification was: (1) Very-low suspicion, 0.85%; (2) Low, 2.6%; (3) Intermediate, 6.7%; and (4) High, 40.9%. The net benefit (NB), expressed as avoided interventions, indicated that the highest capacity to avoid unnecessary fine needle aspiration biopsy (FNAB) in the patterns that we studied was 42, 31, 35, and 43 of every 100 FNABs. The NB calculation for a probability threshold of 11% for each of the ATA suspicion patterns studied is less than that of performing FNAB on all nodules. CONCLUSIONThese three types of analysis have shown that only the ATA high-suspicion diagnostic pattern is clinically useful, in which case, FNAB should be performed. However, the curve decision analysis has demonstrated that using the ATA US risk patterns to decide which patients need FNAB does not provide a greater benefit than performing FNAB on all thyroid nodules. Therefore, it is likely that a better way to approach the assessment of thyroid nodules would be to perform FNAB on all non-cystic nodules, as the present analysis has shown the ATA risk patterns do not provide an adequate clinical decision-making framework.
Distance correlation is a novel class of multivariate dependence measure, taking positive values between 0 and 1, and applicable to random vectors of arbitrary dimensions, not necessarily equal. It ...offers several advantages over the well-known Pearson correlation coefficient, the most important is that distance correlation equals zero if and only if the random vectors are independent. There are two different estimators of the distance correlation available in the literature. The first one, proposed by Székely et al. (2007), is based on an asymptotically unbiased estimator of the distance covariance which turns out to be a V-statistic. The second one builds on an unbiased estimator of the distance covariance proposed in Székely et al. (2014), proved to be an U-statistic by Székely and Huo (2016). This study evaluates their efficiency (mean squared error) and compares computational times for both methods under different dependence structures. Under conditions of independence or near-independence, the V-estimates are biased, while the U-estimator frequently cannot be computed due to negative values. To address this challenge, a convex linear combination of the former estimators is proposed and studied, yielding good results regardless of the level of dependence.
Nowadays, Small and Medium Enterprises (SMEs) that hold a better competitive position have adopted technology as their key element to become competitive in a globalized market. In Mexico, 72% of the ...employment of the country and 52% of the GDP comes from SMEs. The importance of keeping alive and working such entities is crucial for the country and one key element is related to their first years. The following work presents a work in progress expert system for Risk Assessment based on a series of evaluations of indicators that provide an insight of the SMEs economic health. The system is based on a real-life scenario with a tailored knowledge base.
We undertook this study to determine whether anatomic changes after total abdominal hysterectomy are a cause of dyspareunia in premenopausal women.
This is a comparative, prospective and longitudinal ...study in 50 premenopausal women with benign uterine disease without dyspareunia treated with total abdominal hysterectomy. Primary variable was presence of postsurgical dyspareunia. Secondary variables are presurgical and assessment 3 months after surgery of left, right, anterior and posterior vaginal longitude (VLL, VRL, VAL and VPL, respectively) expressed in centimeters, as well as of the vaginal volume (VV). Statistical analysis for mean, central tendency and t-test. Group 1 (G1) is comprised of patients with postsurgical dyspareunia and Group 2 (G2) is comprised of patients without dyspareunia.
In G1, three patients (mean age: 42 years) had dyspareunia, pre- and postsurgical mean values were VV 146.6 and 100, VLL 8 and 7.3, VPL 9.16 and 7.3, VLL 8 and 7.3, VRL 8 and 7.3. In G2, 47 patients (mean age: 40.36 years) were without dyspareunia, pre- and postsurgical values were VV 150.6 and 121.57, VLL 8.81 and 8.12, VPL 9.7 and 8.69, VLL 9.24 and 8.3, VRL 9.28 and 8.33. We did not find significant differences between the groups. Two of the three patients with dyspareunia had a vaginal granuloma, but the third case did not show an anatomical cause.
There is no relationship between total abdominal hysterectomy in premenopausal women and anatomical vaginal changes after surgery as assessed by vaginal volume and longitude. Presence of vaginal granuloma was responsible for dyspareunia in 4% of cases. Dyspareunia was found in 2% of premenopausal women without posthysterectomy anatomical cause.
Background and Aim: Leptospirosis is a re-emerging zoonosis that is under-reported in tropical countries, and canines can be a potential reservoir of the disease. The objective of this study was to ...diagnose Leptospira spp. that is actively infected and re-infected in stray dogs and cats from Bogota, D.C., Colombia. Materials and Methods: A sample of 200 animals, including dogs and cats from the animal protection programs of Bogota, Colombia, were used in this study. Blood was collected from these animals for serum and DNA analysis. Conventional polymerase chain reaction (PCR) was performed using the 16s rRNA primer set, and higher-quality amplification products were sequenced by Sanger. For serodiagnosis, a group of PCR-positive samples was tested using the microagglutination test (MAT). Results: The overall PCR positivity of stray dogs and cats was 56%, 52.9%, and 65.3% in dogs and cats, respectively. The MAT seropositivity was 77.3%, and only dogs showed titers higher than 1:400. Canicola, Icterohaemorrhagiae, Pomona, Hardjo Prajitno, and Canicola and Hardjo prajitno were the serogroups associated with dogs and cats, respectively. Phylogenetic analysis revealed that the strains belonging to Leptospira interrogans serovars related to isolated samples of American, European, and Asian bats (Myotis myotis), dogs, and bovines of American origin. Conclusion: These results showed that stray dogs and cats were previously exposed to different serovars of Leptospira spp. and re-infected with other serovars that actively participated in the transmission cycle. These findings highlight the importance of actively diagnosing infectious animals to design effective intervention strategies. Keywords: cat, dog, Leptospira spp., microagglutination test, phylogenetic analysis, polymerase chain reaction.
BACKGROUND: Dengue fever (DF) is the most prevalent arthropod-borne viral disease affecting humans. The World Health Organization (WHO) proposed a revised classification in 2009 to enable the more ...effective identification of cases of severe dengue (SD). This was designed primarily as a clinical tool, but it also enables cases of SD to be differentiated into three specific subcategories (severe vascular leakage, severe bleeding, and severe organ dysfunction). However, no study has addressed whether this classification has advantage in estimating factors associated with the progression of disease severity or dengue pathogenesis. We evaluate in a dengue outbreak associated risk factors that could contribute to the development of SD according to the 2009 WHO classification. METHODS: A prospective cross-sectional study was performed during an epidemic of dengue in 2009 in Chiapas, Mexico. Data were analyzed for host and viral factors associated with dengue cases, using the 1997 and 2009 WHO classifications. The cost–benefit ratio (CBR) was also estimated. RESULTS: The sensitivity in the 1997 WHO classification for determining SD was 75%, and the specificity was 97.7%. For the 2009 scheme, these were 100% and 81.1%, respectively. The 2009 classification showed a higher benefit (537%) with a lower cost (10.2%) than the 1997 WHO scheme. A secondary antibody response was strongly associated with SD. Early viral load was higher in cases of SD than in those with DF. Logistic regression analysis identified predictive SD factors (secondary infection, disease phase, viral load) within the 2009 classification. However, within the 1997 scheme it was not possible to differentiate risk factors between DF and dengue hemorrhagic fever or dengue shock syndrome. The critical clinical stage for determining SD progression was the transition from fever to defervescence in which plasma leakage can occur. CONCLUSIONS: The clinical phenotype of SD is influenced by the host (secondary response) and viral factors (viral load). The 2009 WHO classification showed greater sensitivity to identify SD in real time. Timely identification of SD enables accurate early decisions, allowing proper management of health resources for the benefit of patients at risk for SD. This is possible based on the 2009 WHO classification.
PDF
