Major inconsistencies of inferred population genetic structure estimated in a large set of domestic horse breeds using microsatellites.

STRUCTURE remains the most applied software aimed at recovering the true, but unknown, population structure from microsatellite or other genetic markers. About 30% of structure-based studies could not be reproduced (Molecular Ecology, 21, 2012, 4925). Here we use a large set of data from 2,323 horses from 93 domestic breeds plus the Przewalski horse, typed at 15 microsatellites, to evaluate how program settings impact the estimation of the optimal number of population clusters K opt that best describe the observed data. Domestic horses are suited as a test case as there is extensive background knowledge on the history of many breeds and extensive phylogenetic analyses. Different methods based on different genetic assumptions and statistical procedures (dapc, flock, PCoA, and structure with different run scenarios) all revealed general, broad-scale breed relationships that largely reflect known breed histories but diverged how they characterized small-scale patterns. structure failed to consistently identify K opt using the most widespread approach, the ΔK method, despite very large numbers of MCMC iterations (3,000,000) and replicates (100). The interpretation of breed structure over increasing numbers of K, without assuming a K opt, was consistent with known breed histories. The over-reliance on K opt should be replaced by a qualitative description of clustering over increasing K, which is scientifically more honest and has the advantage of being much faster and less computer intensive as lower numbers of MCMC iterations and repetitions suffice for stable results. Very large data sets are highly challenging for cluster analyses, especially when populations with complex genetic histories are investigated.

Significance of intra-operative blood pressure data resolution: A retrospective, observational study.

Background: With evolving techniques for analysis of blood pressure (BP) variability, the importance of sampling resolution for intra-operative BP still remains to be examined. This study aims at comparing BP data with beat-by-beat vs. 15 second resolution. Methods: This is a retrospective analysis of intra-arterial BP data obtained from cardiac surgical patients from the intra-operative period. Data was collected from two sources for each patient, one with beat-by-beat frequency, other at a frequency of once every 15 seconds. The fraction of time and area under the curve beyond systolic BP thresholds of 95 - 135 mmHg were calculated using data from both sources, for each patient. These were compared using Wilcoxon ranked sum test for paired samples using R-statistics version 3.4.3. Results: There was a statistically significant difference (P < 0.001) between the parameters from the two sources. This was especially true for parameters below and outside the thresholds. Only time fraction showed significant difference above the 135 mmHg threshold. Conclusion: Our preliminary analysis shows a definitive difference between BP descriptors, depending on sampling resolution. But the impact of this difference on the outcome predicting models of the parameters stands to be ascertained. Future larger studies, powered to examine the impact of sampling resolution on outcome predictive ability of BP descriptors, with special emphasis on dynamic markers of complexity are warranted.

Feasibility of a Spanish/English computerized decision aid to facilitate smoking cessation efforts in underserved communities.

INTRODUCTION: People with poor access to medical care are more likely to smoke but are less likely to receive nicotine dependence treatment. OBJECTIVE: To assess preliminary outcomes of a computer-based, bilingual smoking cessation decision-aid to facilitate utilization of resources. METHODS: A computer kiosk with a smoking cessation decision-aid was integrated at three safety-net clinics and two health fairs. The kiosk queries participants about smoking behaviors, guides them to set a quit date and select treatment, provides printed materials, and prompts fax-referral to quitline. RESULTS: Among the 163 smokers referred to the kiosk, 78.5% participated in the study and 30% completed the kiosk in Spanish. Few had previously used cessation resources. During completion of the decision-aid, 95.3% requested pharmacotherapy, and 70.3% opted for counseling. Among those reached for two-month follow-up (69.5%), 20.2% reported they had quit smoking. CONCLUSION: Spanish/English computerized decision aids are feasible and can facilitate the use of effective treatments for smoking cessation among underserved smokers.

MR quantification of hepatic iron concentration.

PURPOSE: To evaluate the accuracy of magnetic resonance (MR) imaging in the quantification of hepatic iron concentration. MATERIALS AND METHODS: Between April 1999 and June 2001, 112 patients were recruited prospectively. All had undergone liver biopsy and hepatic iron concentration quantification with spectrophotometry, followed by MR imaging. MR imaging involved use of four gradient-echo sequences and one spin-echo sequence. Signal intensity (SI) was measured on images obtained with each sequence by means of regions of interest placed in the liver and paraspinal muscle to obtain the liver-to-muscle SI ratio. The relationship between hepatic iron concentration and SI ratio for each sequence was analyzed with multiple linear regression. Receiver operating characteristic analysis was performed to find the diagnostic thresholds. RESULTS: Sixty-eight patients had normal hepatic iron levels (<36 micromol/g), 23 had hemosiderosis (36-80 micromol/g), and 21 had hemochromatosis (>80 micromol/g). With all sequences, an inverse linear relationship between iron concentration and SI ratio was apparent. The authors generated a mathematic model to estimate the iron concentrations from MR imaging data (r = 0.937). For estimated concentrations of more than 85 micromol/g, the positive predictive value for hemochromatosis was 100%; for those less than 40 micromol/g, the negative predictive value for hemochromatosis was 100%. For estimated concentrations of more than 58 micromol/g, the positive predictive value for iron overload was 100%; for those less than 20 micromol/g, the negative predictive value for iron overload was 100%. CONCLUSION: MR imaging is a useful and noninvasive diagnostic tool for quantification of hepatic iron concentration.