In 1943, Luria and Delbrück used a phage resistance assay to establish spontaneous mutation as a driving force of microbial diversity1. Mutation rates are still studied using such assays, but these can only examine the small minority of mutations conferring survival in a particular condition. Newer approaches, such as long-term evolution followed by whole-genome sequencing 2, 3, may be skewed by mutational “hot” or “cold” spots 3, 4. Both approaches are affected by numerous caveats 5, 6, 7 (see Supplemental Information). We devise a method, Maximum-Depth Sequencing (MDS), to detect extremely rare variants in a population of cells through error-corrected, high-throughput sequencing. We directly measure locus-specific mutation rates in E. coli and show that they vary across the genome by at least an order of magnitude. Our data suggest that certain types of nucleotide misincorporation occur 104-fold more frequently than the basal rate of mutations, but are repaired in vivo. Our data also suggest specific mechanisms of antibiotic-induced mutagenesis, including downregulation of mismatch repair via oxidative stress; transcription-replication conflicts; and in the case of fluoroquinolones, direct damage to DNA.

Purpose: The pathophysiology of nocturia and nocturnal polyuria (NP), conditions that become more prevalent with aging, may in part be explained by changes in hormones involved in water homeostasis. The purpose of this study was to analyze the impact of aging on urinary natriuretic peptides in nocturia and NP.Methods: Patients aged ≥18 years completed 24-hour bladder diaries for assessment of nocturia and NP. They were divided into subgroups of ≥65 years old and <65 years old. Urine samples were collected and analyzed for natriuretic peptide (NT-proANP, NT-proBNP, and NT-proCNP) levels. Peptide levels were compared between patients with and without nocturia/NP and within age subgroups; correlation to the NP index (NPi) was determined.Results: Compared to patients without nocturia (N=15), patients with nocturia (N=36) had higher median levels of urinary NT-proANP (15.8 pmol/mmol Cr vs. 10.9 pmol/mmol Cr, P=0.016) and NT-proBNP (6.3 pmol/mmol Cr vs. 4.5 pmol/mmol Cr, P=0.021), but showed no differences in NT-proCNP (2.4 pmol/mmol Cr vs. 2.5 pmol/mmol Cr, P=0.967). Patients ≥65 years old with nocturia had higher NT-proANP (29.8 pmol/mmol Cr vs. 11.0 pmol/mmol Cr, P<0.001) and NT-proBNP (9.6 pmol/mmol Cr vs. 5.0 pmol/mmol Cr, P<0.001) than patients <65 years old. Additionally, patients with NP (N=30) showed higher urinary NT-proANP (19.6 pmol/mmol Cr vs. 10.5 pmol/mmol Cr, P<0.001) and NT-proBNP (6.7 pmol/mmol Cr vs. 4.7 pmol/mmol Cr, P=0.020) compared to patients without NP (N=21). NP patients ≥65 years had higher NT-proANP (29.8 pmol/mmol Cr vs. 12.5 pmol/mmol Cr, P<0.001) and NT-proBNP (9.6 pmol/mmol Cr vs. 4.4 pmol/mmol Cr, P=0.004) than patients <65 years old. NPi positively correlated with urinary NT-proANP (R_S=0.417, P=0.002) and NT-proBNP (R_S=0.303, P=0.031), but not with NT-proCNP (R_S=-0.094, P=0.510).Conclusions: Since urinary NT-proANP and NT-proBNP were greater in aged patients with nocturia and NP, natriuretic peptides may contribute to the pathophysiology of these conditions and further research should aim to explore them as targets for management.

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Hypertrophic cardiomyopathy (HCM), now recognized as a common cardiomyopathy of complex genomics and pathophysiology, is defined by the presence of left ventricular hypertrophy of various morphologies and severity, significant hemodynamic consequences, and diverse phenotypic, both structural and clinical, profiles. Advancements in cardiac multimodality imaging, including echocardiography, cardiac magnetic resonance imaging, and cardiac computed tomography, with and without angiography have greatly improved the diagnosis of HCM, and enable precise measurements of cardiac mass, volume, wall thickness, function, and physiology. Multimodality imaging provides comprehensive and complementary information and hasemerged as the bedrock for the diagnosis, clinical assessment, serial monitoring, and sudden cardiac death risk stratification of patients with HCM. This review highlights the role of cardiac multimodality imaging in the modern diagnosis and management of HCM.