Ureteral stent after PCNL: is leaving the threads through the percutaneous tract safe and better tolerated?

OBJECTIVE: To assess safety, urinary symptoms, and feasibility of JJ stent removal with exteriorized threads through the percutaneous tract after percutaneous nephrolithotomy (PCNL). MATERIALS AND METHODS: Prospective, transversal, comparative, experimental, randomized 1-to-1 cohort study in 52 patients who underwent "tubeless" PCNL from October 2020 to November 2022. Group A with threads through the urethra and Group B through the percutaneous tract. The validated USSQ (Ureteral Stent Symptom Questionnaire) was applied in the Urology office a week after the procedure, and the JJ stent was withdrawn by pulling the threads. Hemoglobin and urine culture, and pre- and post-surgery were evaluated. RESULTS: There is a statistically significant difference in favor of group B when comparing urinary symptoms (p = 0.008), body pain (p = 0.009), and general condition (p = 0.042), mainly for non-urgency incontinence, frequency of analgesic use, and dysuria. There were significant differences between groups (p = 0.028, p = 0.026, p = 0.027, respectively). There is no association with urinary infections (p = 0.603) nor an increased risk of bleeding (p = 0.321). CONCLUSION: The removal of the JJ stent with exteriorized threads through the percutaneous tract after PCNL in the office is a feasible and safe procedure if it is removed before 8 days and has better tolerance regarding the urinary symptoms.

Mendelian Randomisation Confirms the Role of Y-Chromosome Loss in Alzheimer's Disease Aetiopathogenesis in Men.

Mosaic loss of chromosome Y (mLOY) is a common ageing-related somatic event and has been previously associated with Alzheimer's disease (AD). However, mLOY estimation from genotype microarray data only reflects the mLOY degree of subjects at the moment of DNA sampling. Therefore, mLOY phenotype associations with AD can be severely age-confounded in the context of genome-wide association studies. Here, we applied Mendelian randomisation to construct an age-independent mLOY polygenic risk score (mloy-PRS) using 114 autosomal variants. The mloy-PRS instrument was associated with an 80% increase in mLOY risk per standard deviation unit (p = 4.22 × 10-20) and was orthogonal with age. We found that a higher genetic risk for mLOY was associated with faster progression to AD in men with mild cognitive impairment (hazard ratio (HR) = 1.23, p = 0.01). Importantly, mloy-PRS had no effect on AD conversion or risk in the female group, suggesting that these associations are caused by the inherent loss of the Y chromosome. Additionally, the blood mLOY phenotype in men was associated with increased cerebrospinal fluid levels of total tau and phosphorylated tau181 in subjects with mild cognitive impairment and dementia. Our results strongly suggest that mLOY is involved in AD pathogenesis.

Clinical Impact of the COVID-19 Pandemic in Mexican Patients with Thoracic Malignancies.

BACKGROUND: Accumulated evidence indicates that patients with lung cancer are a vulnerable population throughout the pandemic. Limited information is available in Latin America regarding the impact of the pandemic on medical care. The goal of this study was to describe the clinical and social effect of COVID-19 on patients with thoracic cancer and to ascertain outcomes in those with a confirmed diagnosis. MATERIALS AND METHODS: This cohort study included patients with thoracic neoplasms within a single institution between March 1, 2020, and February 28, 2021. All variables of interest were extracted from electronic medical records. During this period, the Depression Anxiety and Stress Scale 21 (DASS-2) was applied to evaluate and identify more common psychological disorders. RESULTS: The mean age for the total cohort (n = 548) was 61.5 ± 12.9 years; non-small cell lung cancer was the most frequent neoplasm (86.9%), advanced stages predominated (80%), and most patients were under active therapy (82.8%). Any change in treatment was reported in 23.9% of patients, of which 78.6% were due to the COVID-19 pandemic. Treatment delays (≥7 days) were the most frequent modifications in 41.9% of cases, followed by treatment suspension at 37.4%. Patients without treatment changes had a more prolonged progression-free survival and overall survival (hazard ratio [HR] 0.21, p < .001 and HR 0.28, p < .001, respectively). The mean DASS-21 score was 10.45 in 144 evaluated patients, with women being more affected than men (11.41 vs. 9.08, p < .001). Anxiety was reported in 30.5% of cases, followed by depression and distress in equal proportions (18%). Depressed and stressed patients had higher odds of experiencing delays in treatment than patients without depression (odds ratio [OR] 4.5, 95% confidence interval [CI] 1.53-13.23, p = .006 and OR 3.18, 95% CI 1.2-10.06, p = .006, respectively). CONCLUSION: Treatment adjustments in patients with thoracic malignancies often occurred to avoid COVID-19 contagion with detrimental effects on survival. Psychological disorders could have a role in adherence to the original treatment regimen. IMPLICATIONS FOR PRACTICE: The pandemic has placed an enormous strain on health care systems globally. Patients with thoracic cancers represent a vulnerable population, with increased morbidity and mortality rates. In Mexico, treatment modifications were common during the pandemic, and those who experienced delays had worse survival outcomes. Most treatment modifications were related to a patient decision rather than a lockdown of health care facilities in which mental health impairment plays an essential role. Moreover, the high case fatality rate highlights the importance of improving medical care access. Likewise, to develop strategies facing future threats that may compromise health care systems in non-developed countries.

Percutaneous nephrolithotomy with ultrasound-assisted puncture: does the technique reduce dependence on fluoroscopic ionizing radiation?

PURPOSE: The ultrasound-guided (US) puncture in percutaneous nephrolithotomy (PCNL) has demonstrated advantages over traditional fluoroscopy access. The aim of this study was to demonstrate the reduction of fluoroscopy time using this technique during PCNL as the surgeon gained experience. METHODS: Transversal study performed on 30 consecutive patients undergoing PCNL from March to November 2019. All punctures were performed with US guidance. The patients were divided into 2 groups of 15 each according to the chronological order of the intervention. Demographic data, preoperative parameters, puncture time, fluoroscopy time, stone-free rate and complications were analyzed. RESULTS: The time of fluoroscopy was considerably reduced as the experience in the number of cases increased, reducing from 83.09 ± 47.8 s in group 1 to 22.8 ± 10.3 s in group 2 (p < 0.01), the time required to perform the puncture was reduced of 108.1 ± 68.9 s in group 1, to 92.6 ± 94.7 s in group 2 (p < 0.67). Stone free rate of 83.3% was obtained globally. CONCLUSION: US percutaneous renal access is safe and reproducible technique; the main advantage is to reduce exposure to radiation without compromising clinical results and has a short learning curve for urologists with prior experience in PCNL.

Predictors of perpetration of men's same-sex partner violence.

This study examined alcohol consumption, internalized homophobia, and outness as related to men's (N = 107) reports of the perpetration of violence against a same-sex partner. Higher typical weekly alcohol consumption, higher levels of internalized homophobia, and less outness (e.g., lower levels of disclosure of one's sexual orientation) predicted the perpetration of partner violence. In contrast to what we expected, the interaction between higher alcohol consumption and higher levels of outness about one's sexual orientation (i.e., being open to friends, family members, work colleagues) increased the likelihood of participants' reports of perpetrating physical violence. These results suggest the importance of both alcohol consumption and sexual minority stressors and their interactions in understanding men's perpetration of same-sex partner violence.

An African ancestry-specific allele of CTLA4 confers protection against rheumatoid arthritis in African Americans.

Cytotoxic T-lymphocyte associated protein 4 (CTLA4) is a negative regulator of T-cell proliferation. Polymorphisms in CTLA4 have been inconsistently associated with susceptibility to rheumatoid arthritis (RA) in populations of European ancestry but have not been examined in African Americans. The prevalence of RA in most populations of European and Asian ancestry is approximately 1.0%; RA is purportedly less common in black Africans, with little known about its prevalence in African Americans. We sought to determine if CTLA4 polymorphisms are associated with RA in African Americans. We performed a 2-stage analysis of 12 haplotype tagging single nucleotide polymorphisms (SNPs) across CTLA4 in a total of 505 African American RA patients and 712 African American controls using Illumina and TaqMan platforms. The minor allele (G) of the rs231778 SNP was 0.054 in RA patients, compared to 0.209 in controls (4.462 x 10(-26), Fisher's exact). The presence of the G allele was associated with a substantially reduced odds ratio (OR) of having RA (AG+GG genotypes vs. AA genotype, OR 0.19, 95% CI: 0.13-0.26, p = 2.4 x 10(-28), Fisher's exact), suggesting a protective effect. This SNP is polymorphic in the African population (minor allele frequency [MAF] 0.09 in the Yoruba population), but is very rare in other groups (MAF = 0.002 in 530 Caucasians genotyped for this study). Markers associated with RA in populations of European ancestry (rs3087243 [+60C/T] and rs231775 [+49A/G]) were not replicated in African Americans. We found no confounding of association for rs231778 after stratifying for the HLA-DRB1 shared epitope, presence of anti-cyclic citrullinated peptide antibody, or degree of admixture from the European population. An African ancestry-specific genetic variant of CTLA4 appears to be associated with protection from RA in African Americans. This finding may explain, in part, the relatively low prevalence of RA in black African populations.

Impact of the use of molecular techniques (PCR) on detection and eradication success against Helicobacter pylori.

INTRODUCTION: Helicobacter pylori infection affects more than 50% of the world population. Increased antibiotic resistance is the main cause of treatment failure. The main objective was to analyze the eradication success after the application of the new ESPGHAN treatment recommendations and the introduction of PCR as a direct diagnosis technique, describe the evolution of the local pattern of antibiotic resistance, and assess the cost-effectiveness of PCR application, isolated or in conjunction with culture as a diagnostic strategy. PATIENTS AND METHODS: Retrospective descriptive study of all microbiological isolates of Helicobacter pylori in 2013-2019 in our center, by comparing the percentage of resistance and eradication success between the periods 2013-2016 and 2017-2019. Cost-effectiveness study of direct diagnostic tests, comparing 3 different options: culture and PCR; only culture; PCR only. RESULTS: 192 patients were included, 98 were detected by culture (2013-2016) and 94 by culture and/or PCR (2017-2019). Antibiotic treatment was established in 153 patients, 90 in the first period (2011 ESPGHAN guidelines: eradication percentage 62.2%), 63 in the second (2017 ESPGHAN guidelines: eradication percentage: 73%). An increase in resistance to clarithromycin was observed, going from 16.3% (n=16) in the first period, to 53.2% (n=48) in 2017-2019 (98% detected by PCR, 60% by culture). There were no differences in the rest of antibiotic resistances. The isolated PCR application presented a cost-effectiveness analysis ratio (CEAR) of 71.91, compared to 92.16 for the culture and 96.35 for the culture and PCR combined. CONCLUSIONS: The application of the ESPGHAN 2017 guidelines achieved greater eradication success, although less than that observed in previous publications, without reaching the target of at least 90%. An increase in resistance to macrolides was observed, without being able to discriminate whether it is a real increase or a greater diagnostic sensitivity of molecular techniques, with the isolated request for PCR being the most cost-effective strategy.

Comparing self-reported ethnicity to genetic background measures in the context of the Multi-Ethnic Study of Atherosclerosis (MESA).

BACKGROUND: Questions remain regarding the utility of self-reported ethnicity (SRE) in genetic and epidemiologic research. It is not clear whether conditioning on SRE provides adequate protection from inflated type I error rates due to population stratification and admixture. We address this question using data obtained from the Multi-Ethnic Study of Atherosclerosis (MESA), which enrolled individuals from 4 self-reported ethnic groups. We compare the agreement between SRE and genetic based measures of ancestry (GBMA), and conduct simulation studies based on observed MESA data to evaluate the performance of each measure under various conditions. RESULTS: Four clusters are identified using 96 ancestry informative markers. Three of these clusters are well delineated, but 30% of the self-reported Hispanic-Americans are misclassified. We also found that MESA SRE provides type I error rates that are consistent with the nominal levels. More extensive simulations revealed that this finding is likely due to the multi-ethnic nature of the MESA. Finally, we describe situations where SRE may perform as well as a GBMA in controlling the effect of population stratification and admixture in association tests. CONCLUSIONS: The performance of SRE as a control variable in genetic association tests is more nuanced than previously thought, and may have more value than it is currently credited with, especially when smaller replication studies are being considered in multi-ethnic samples.

Most common single-nucleotide polymorphisms associated with rheumatoid arthritis in persons of European ancestry confer risk of rheumatoid arthritis in African Americans.

OBJECTIVE: Large-scale genetic association studies have identified >20 rheumatoid arthritis (RA) risk alleles among individuals of European ancestry. The influence of these risk alleles has not been comprehensively studied in African Americans. We therefore sought to examine whether these validated RA risk alleles are associated with RA risk in an African American population. METHODS: Twenty-seven candidate single-nucleotide polymorphisms (SNPs) were genotyped in 556 autoantibody-positive African Americans with RA and 791 healthy African American control subjects. Odds ratios (ORs) and 95% confidence intervals (95% CIs) for each SNP were compared with previously published ORs for RA patients of European ancestry. We then calculated a composite genetic risk score (GRS) for each individual based on the sum of all risk alleles. RESULTS: Overlap of the ORs and 95% CIs between the European and African American populations was observed for 24 of the 27 candidate SNPs. Conversely, 3 of the 27 SNPs (CCR6 rs3093023, TAGAP rs394581, and TNFAIP3 rs6920220) demonstrated ORs in the opposite direction from those reported for RA patients of European ancestry. The GRS analysis indicated a small but highly significant probability that African American patients relative to control subjects were enriched for the risk alleles validated in European RA patients (P = 0.00005). CONCLUSION: The majority of RA risk alleles previously validated for RA patients of European ancestry showed similar ORs in our population of African Americans with RA. Furthermore, the aggregate GRS supports the hypothesis that these SNPs are risk alleles for RA in the African American population. Future large-scale genetic studies are needed to validate these risk alleles and identify novel RA risk alleles in African Americans.

[Impact of the use of molecular techniques (PCR) on detection and eradication success against Helicobacter pylori]. / Impacto del uso de las técnicas moleculares (PCR) en la detección y el éxito erradicador frente a Helicobacter pylori.

INTRODUCTION: Helicobacter pylori (H. pylori) infection affects more than 50% of the world population. Increased antibiotic resistance is the main cause of treatment failure. The main objective was to analyze the eradication success after the application of the new ESPGHAN treatment recommendations and the introduction of PCR as a direct diagnosis technique, describe the evolution of the local pattern of antibiotic resistance, and assess the cost-effectiveness of PCR application, isolated or in conjunction with culture as a diagnostic strategy. PATIENTS AND METHODS: retrospective descriptive study of all microbiological isolates of H. pylori in 2013-2019 in our center, by comparing the percentage of resistance and eradication success between the periods 2013-2016 and 2017-2019. Cost-effectiveness study of direct diagnostic tests, comparing 3 different options: culture and PCR; only culture; PCR only. RESULTS: 192 patients were included, 98 were detected by culture (2013-2016) and 94 by culture and / or PCR (2017-2019). Antibiotic treatment was established in 153 patients, 90 in the first period (2011 ESPGHAN guidelines: eradication percentage 62.2%), 63 in the second (2017 ESPGHAN guidelines: eradication percentage: 73%). An increase in resistance to clarithromycin was observed, going from 16.3% (n=16) in the first period, to 53.2% (n=48) in 2017-2019 (98% detected by PCR, 60% by culture). There were no differences in the rest of antibiotic resistances. The isolated PCR application presented a cost-effectiveness analysis ratio (CEAR) of 71.91, compared to 92.16 for the culture and 96.35 for the culture and PCR combined. CONCLUSIONS: the application of the ESPGHAN 2017 guidelines achieved greater eradication success, although less than that observed in previous publications, without reaching the target of at least 90%. An increase in resistance to macrolides was observed, without being able to discriminate whether it is a real increase or a greater diagnostic sensitivity of molecular techniques, with the isolated request for PCR being the most cost-effective strategy.

[Correlation between insufficiency or deficiency of vitamin D levels and interleukins 1ß and 6]. / Correlación entre la insuficiencia o deficiencia de los niveles de vitamina D y las interleucinas 1ß y 6.

OBJECTIVES: The primary objective of this study was to define the relationship between vitamin D levels and interleukins (IL) 1ß and 6 as inflammatory markers in a healthy population. As a secondary objective, to measure the prevalence of insufficiency/ deficiency of vitamin D in the same population. METHODS: A sample of 43 healthy blood donors, without chronic-degenerative, inflammatory, or infectious diseases, and without obesity, was selected. Serum levels of IL-1ß and IL-6 were measured in individuals with insufficiency or deficiency of vitamin D. The correlation between vitamin D and interleukins was measured using Spearman's rho. RESULTS: No correlation was found between levels of vitamin D and interleukins. In addition, a prevalence of insufficiency/deficiency of vitamin D was found in 95.3% of the sample. CONCLUSIONS: In healthy subjects with deficiency or insufficiency of vitamin D, there is no association between the levels of this vitamin and IL-1ß and IL-6.

Objetivos: El objetivo primario de este estudio fue definir la relación entre los niveles de vitamina D y las interleucinas (IL) 1ß y 6, como marcadores inflamatorios en población sana. Como objetivo secundario, medir la prevalencia de insuficiencia/deficiencia de vitamina D en la misma población. Métodos: Se seleccionó una muestra de 43 donadores de sangre sanos, sin enfermedades crónico-degenerativas, inflamatorias o infecciosas, y sin obesidad. A los individuos con insuficiencia o deficiencia de vitamina D se les midieron niveles séricos de IL-1ß e IL-6. Se midió la correlación de vitamina D e interleucinas mediante rho de Spearman. Resultados: No se encontró correlación entre los niveles de vitamina D y las interleucinas. Adicionalmente, se encontró una prevalencia de insuficiencia/deficiencia de vitamina D en 95.3 % de la muestra. Conclusiones: En sujetos sanos con deficiencia o insuficiencia de vitamina D, no existe correlación entre los niveles de esta vitamina y de IL-1ß e IL-6.

Commonality of functional annotation: a method for prioritization of candidate genes from genome-wide linkage studies.

Linkage studies of complex traits frequently yield multiple linkage regions covering hundreds of genes. Testing each candidate gene from every region is prohibitively expensive and computational methods that simplify this process would benefit genetic research. We present a new method based on commonality of functional annotation (CFA) that aids dissection of complex traits for which multiple causal genes act in a single pathway or process. CFA works by testing individual Gene Ontology (GO) terms for enrichment among candidate gene pools, performs multiple hypothesis testing adjustment using an estimate of independent tests based on correlation of GO terms, and then scores and ranks genes annotated with significantly-enriched terms based on the number of quantitative trait loci regions in which genes bearing those annotations appear. We evaluate CFA using simulated linkage data and show that CFA has good power despite being conservative. We apply CFA to published linkage studies investigating age-of-onset of Alzheimer's disease and body mass index and obtain previously known and new candidate genes. CFA provides a new tool for studies in which causal genes are expected to participate in a common pathway or process and can easily be extended to utilize annotation schemes in addition to the GO.

Multiple imputation to correct for measurement error in admixture estimates in genetic structured association testing.

OBJECTIVES: Structured association tests (SAT), like any statistical model, assumes that all variables are measured without error. Measurement error can bias parameter estimates and confound residual variance in linear models. It has been shown that admixture estimates can be contaminated with measurement error causing SAT models to suffer from the same afflictions. Multiple imputation (MI) is presented as a viable tool for correcting measurement error problems in SAT linear models with emphasis on correcting measurement error contaminated admixture estimates. METHODS: Several MI methods are presented and compared, via simulation, in terms of controlling Type I error rates for both non-additive and additive genotype coding. RESULTS: Results indicate that MI using the Rubin or Cole method can be used to correct for measurement error in admixture estimates in SAT linear models. CONCLUSION: Although MI can be used to correct for admixture measurement error in SAT linear models, the data should be of reasonable quality, in terms of marker informativeness, because the method uses the existing data to borrow information in which to make the measurement error corrections. If the data are of poor quality there is little information to borrow to make measurement error corrections.

The Case for Examining and Treating the Combined Effects of Parental Drug Use and Interparental Violence on Children in their Homes.

This review examines what have been, to this point, generally two divergent lines of research: (a) effects of parental drug abuse on children, and (b) effects of children's exposure to interparental violence. A small, but growing body of literature has documented the robust relationship between drug use and intimate partner violence. Despite awareness of the interrelationship, little attention has been paid to the combined effect of these deleterious parent behaviors on children in these homes. Thus, we argue for the need to examine the developmental impact of these behaviors (both individually and combined) on children in these homes and for treatment development to reflect how each of these parent behaviors may affect children of substance abusers.

Factors associated with residual symptom burden in patients with peritoneal dialysis: a cohort study / Factores asociados a carga sintomática residual en pacientes con diálisis peritoneal: estudio de cohorte

BACKGROUND: Patients on peritoneal dialysis have residual symptoms that reduce their quality of life. OBJECTIVE: To determine the associated factors of residual symptom burden in patients with continuous ambulatory peritoneal dialysis (CAPD). MATERIAL AND MEHOTDS: An observational, longitudinal, prospective and analytical study was carried out in patients with chronic kidney disease, who were candidates for peritoneal dialysis. The Palliative Care Outcome Scale-Symptoms Renal (POS-S Renal) questionnaire was applied in predialysis and 3 months after CAPD. The residual symptom burden was determined three months after CAPD with a value ≥ 8 points of the POS-S Renal questionnaire. The clinical and biochemical variables coded in a dichotomous manner were compared with the residual symptom burden. Relative risk (RR) with 95% confidence intervals and logistic regression models were calculated. RESULTS: Seventy patients were included. The mean of glomerular filtration rate (GFR) was 4.7 ± 2 ml/min/1.73 m2. The median of the POS-S Renal score in predialysis was 30 points, and 3 months after CAPD was 8 points. The slight symptom burden predialysis presented a RR of 0.18. CONCLUSIONS: The slight symptom burden predialysis is a protective factor independent for residual symptom burden three months after CAPD.

INTRODUCCIÓN: Los pacientes en diálisis peritoneal presentan síntomas residuales que reducen su calidad de vida. OBJETIVO: Determinar los factores asociados a la carga sintomática residual en pacientes con diálisis peritoneal continua ambulatoria (DPCA). MATERIAL Y MÉTODOS: Estudio observacional, longitudinal, prospectivo y analítico. Se incluyeron pacientes con enfermedad renal crónica candidatos a diálisis peritoneal. Se les aplicó el cuestionario Palliative Care Outcome Scale-Symptoms Renal (POS-S Renal) en prediálisis y a los 3 meses de DPCA. Se determinó la carga sintomática residual a los 3 meses de DPCA con un valor ≥ 8 puntos del cuestionario POS-S Renal. Las variables clínicas y bioquímicas codificadas de forma dicotómica fueron comparadas con la carga sintomática residual. Se calcularon el riesgo relativo (RR), los intervalos de confianza del 95% y los modelos de regresión logística. RESULTADOS: Se incluyeron 70 pacientes. La media de la tasa de filtrado glomerular fue de 4.7 ± 2 ml/min/1.73 m2. La mediana de la puntuación POS-S Renal en prediálisis fue de 30 puntos y a los 3 meses de la DPCA fue de 8 puntos. La carga sintomática leve prediálisis presentó un RR de 0.18. CONCLUSIONES: La carga sintomática leve prediálisis es un factor protector independiente de la carga sintomática residual a los 3 meses de la DPCA.

Regional admixture mapping and structured association testing: conceptual unification and an extensible general linear model.

Individual genetic admixture estimates, determined both across the genome and at specific genomic regions, have been proposed for use in identifying specific genomic regions harboring loci influencing phenotypes in regional admixture mapping (RAM). Estimates of individual ancestry can be used in structured association tests (SAT) to reduce confounding induced by various forms of population substructure. Although presented as two distinct approaches, we provide a conceptual framework in which both RAM and SAT are special cases of a more general linear model. We clarify which variables are sufficient to condition upon in order to prevent spurious associations and also provide a simple closed form "semiparametric" method of evaluating the reliability of individual admixture estimates. An estimate of the reliability of individual admixture estimates is required to make an inherent errors-in-variables problem tractable. Casting RAM and SAT methods as a general linear model offers enormous flexibility enabling application to a rich set of phenotypes, populations, covariates, and situations, including interaction terms and multilocus models. This approach should allow far wider use of RAM and SAT, often using standard software, in addressing admixture as either a confounder of association studies or a tool for finding loci influencing complex phenotypes in species as diverse as plants, humans, and nonhuman animals.

Review and evaluation of methods correcting for population stratification with a focus on underlying statistical principles.

When two or more populations have been separated by geographic or cultural boundaries for many generations, drift, spontaneous mutations, differential selection pressures and other factors may lead to allele frequency differences among populations. If these 'parental' populations subsequently come together and begin inter-mating, disequilibrium among linked markers may span a greater genetic distance than it typically does among populations under panmixia [see glossary]. This extended disequilibrium can make association studies highly effective and more economical than disequilibrium mapping in panmictic populations since less marker loci are needed to detect regions of the genome that harbor phenotype-influencing loci. However, under some circumstances, this process of intermating (as well as other processes) can produce disequilibrium between pairs of unlinked loci and thus create the possibility of confounding or spurious associations due to this population stratification. Accordingly, researchers are advised to employ valid statistical tests for linkage disequilibrium mapping allowing conduct of genetic association studies that control for such confounding. Many recent papers have addressed this need. We provide a comprehensive review of advances made in recent years in correcting for population stratification and then evaluate and synthesize these methods based on statistical principles such as (1) randomization, (2) conditioning on sufficient statistics, and (3) identifying whether the method is based on testing the genotype-phenotype covariance (conditional upon familial information) and/or testing departures of the marginal distribution from the expected genotypic frequencies.

The use of plasmodes as a supplement to simulations: A simple example evaluating individual admixture estimation methodologies.

With the advent of powerful computers, simulation studies are becoming an important tool in statistical methodology research. However, computer simulations of a specific process are only as good as our understanding of the underlying mechanisms. An attractive supplement to simulations is the use of plasmode datasets. Plasmodes are data sets that are generated by natural biologic processes, under experimental conditions that allow some aspect of the truth to be known. The benefit of the plasmode approach is that the data are generated through completely natural processes, thus circumventing the common concern of the realism and accuracy of computer simulated data. The estimation of admixture, or the proportion of an individual's genome that originates from different founding populations, is a particularly difficult research endeavor that is well suited to the use of plasmodes. Current methods have been tested with simulations of complex populations where the underlying mechanisms such as the rate and distribution of recombination are not well understood. To demonstrate the utility of this method data derived from mouse crosses is used to evaluate the effectiveness of several admixture estimation methodologies. Each cross shares a common founding population so that the ancestry proportion for each individual is known, allowing for the comparison of true and estimated individual admixture values. Analysis shows that the different estimation methodologies (Structure, AdmixMap and FRAPPE) examined all perform well with simple datasets. However, the performance of the estimation methodologies varied greatly when applied to a plasmode consisting of three founding populations. The results of these examples illustrate the utility of plasmodes in the evaluation of statistical genetics methodologies.

[Educative posture estimation of the doctors with and without educational formation]. / Estimación de la postura ante la educación de médicos con y sin formación docente.

BACKGROUND: The professor's education posture (PEP) is a clearly indicator of the teaching practice that he or she realizes. Our objective was to estimate the presence of the PEP on medic groups with teaching formation: participative, traditional and without formation. METHODS: AN instrument was constructed and validated to estimate the presence of the PEP on three medic groups that work in two different medic units of high specialty in the north zone of Mexico City. RESULTS: The instrument was applied in the evaluation of the PEP to 86 physicians, it was observed significant statistical differences in the development of the physicians that had realized a methodology qualify in teaching with a participative focus. CONCLUSIONS: It is observed the development of an PEP in the physicians that have a teaching formation under a participative focus versus other physicians that had not the same teaching formation.

[Clinical aptitude of residents that attend patients with the cervical intraepithelial neoplasia]. / Aptitud clínica de médicos residentes en la atención de pacientes con neoplasia intraepitelial cervical.

OBJECTIVE: To build, validate and apply an instrument to evaluate the clinical aptitude in intraepitelial cervical neoplasia (ICN) in residents. METHODS: The instrument included four clinical real cases, validated by experts and included 106 items using true, false and don't know answers. A pilot test and the 21 Kuder-Richardson formula were used to estimate consistency. It was applied to residents, in an observational, transversal, comparative and open study, including 11 second year residents, 13 third year residents and 12 fourth year residents. RESULTS: Consistency of 0.88 was obtained; 22% were located in the middle level, 39% were located in the low level and 39% in the very low level. There were no residents in the high or very high level or by chance answer level. The Kruskal-Wallis test showed significant differences among the three groups and with the U test of Mann Whitney there were no differences between groups. CONCLUSIONS: The year of residence did not show differences in the development of clinical aptitude in ICN. Most of the residents were located in the inferior level of clinical aptitude. This study makes evident the need to reframe our educative processes in a qualitative different manner.