1,221 research outputs found

    Direct detection of methylation in genomic DNA

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    The identification of methylated sites on bacterial genomic DNA would be a useful tool to study the major roles of DNA methylation in prokaryotes: distinction of self and nonself DNA, direction of post-replicative mismatch repair, control of DNA replication and cell cycle, and regulation of gene expression. Three types of methylated nucleobases are known: N(6)-methyladenine, 5-methylcytosine and N(4)-methylcytosine. The aim of this study was to develop a method to detect all three types of DNA methylation in complete genomic DNA. It was previously shown that N(6)-methyladenine and 5-methylcytosine in plasmid and viral DNA can be detected by intersequence trace comparison of methylated and unmethylated DNA. We extended this method to include N(4)-methylcytosine detection in both in vitro and in vivo methylated DNA. Furthermore, application of intersequence trace comparison was extended to bacterial genomic DNA. Finally, we present evidence that intrasequence comparison suffices to detect methylated sites in genomic DNA. In conclusion, we present a method to detect all three natural types of DNA methylation in bacterial genomic DNA. This provides the possibility to define the complete methylome of any prokaryote

    The Groningen electrocardiographic criteria for left ventricular hypertrophy:a sex-specific analysis

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    The sensitivity of electrocardiogram (ECG) criteria to detect left ventricular hypertrophy (LVH) is low, especially in women. We determined sex-specific sensitivities of ECG-LVH criteria, and developed new criteria, using cardiovascular magnetic resonance imaging (CMR). Sensitivities of ECG-LVH criteria were determined in participants of the UK Biobank (N = 3632). LVH was defined when left ventricular mass was > 95% confidence interval (CI) according to age and sex. In a training cohort (75%, N = 2724), sex-specific ECG-LVH criteria were developed by investigating all possible sums of QRS-amplitudes in all 12 leads, and selecting the sum with the highest pseudo-R2 and area under the curve to detect LVH. Performance was assessed in a validation cohort (25%, N = 908), and association with blood pressure change was investigated in an independent cohort. Sensitivities of ECG-LVH criteria were low, especially in women. Newly developed Groningen-LVH criterion for women (QV2 + RI + RV5 + RV6 + SV2 + SV4 + SV5 + SV6) outperformed all ECG-LVH criteria with a sensitivity of 42% (95% CI 35-49%). In men, newly developed criterion ((RI + RV5 + SII + SV2 + SV6) × QRS duration) was equally sensitive as 12-lead sum with a sensitivity of 44% (95% CI 37-51%) and outperformed the other criteria. In an independent cohort, the Groningen-LVH criteria were strongest associated with change in systolic blood pressure. Our proposed CMR sex-specific Groningen-LVH criteria improve the sensitivity to detect LVH, especially in women. Further validation and its association with clinical outcomes is warranted

    Effect of Systolic Blood Pressure on Left Ventricular Structure and Function A Mendelian Randomization Study

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    We aimed to estimate the effects of a lifelong exposure to high systolic blood pressure (SBP) on left ventricular (LV) structure and function using Mendelian randomization. A total of 5596 participants of the UK Biobank were included for whom cardiovascular magnetic resonance imaging and genetic data were available. Major exclusion criteria included nonwhite ethnicity, major cardiovascular disease, and body mass index >30 o
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