Correction to: Cluster identification, selection, and description in Cluster randomized crossover trials: the PREP-IT trials

An amendment to this paper has been published and can be accessed via the original article

Preventing Fragility Fractures: A 3-Month Critical Window of Opportunity

Introduction: Low-energy falls are the leading cause of injury-related morbidity and mortality in the elderly. In the past, physicians focused on treating fractures resulting from falls rather than preventing them. The purpose of this study is to identify patients with a hospital encounter for fall prior to a fracture as an opportunity for pre-injury intervention when patients might be motivated to engage in falls prevention. Materials & Methods: A retrospective analysis of all emergency room and inpatient encounters in 2016 with an ICD10 diagnosis code including “fall” across a tri-state health system was performed. Subsequent encounters with diagnosis of fracture within 2 years were then identified. Data was collected for time to subsequent fracture, fracture type and location, and length of stay of initial encounter. Results: There were 12,382 encounters for falls among 10,589 patients. Of those patients, 1,040 (9.8%) sustained a subsequent fracture. Fractures were most commonly lower extremity fractures (661 fractures; 63.5%), including hip fractures (447 fractures; 45.87%). Median time from fall to fracture was 105 days (IQR 16-359 days). Discussion: Falls are an important, modifiable risk factor for fragility fracture. This study demonstrates that patients are presenting to the hospital with one of the main modifiable risk factors for fracture within a time window that allows for intervention. Conclusions: Presentation to the hospital for a fall is a vital opportunity to intervene and prevent subsequent fracture in a high-risk population

Variation of gene conversion frequencies (P values).

*<p>Indicates significance at P<0.05.</p

Gene conversion test loci.

<p>(A) After pre-meiotic DNA synthesis, meiocytes in plants that are heterozygous for fluorescent and non-fluorescent alleles of the FTL transgene cassettes will have two copies of each allele. (B) Following meiosis those alleles will segregate in pollen tetrads. If no gene conversion occurs at the test locus the fluorescent signal will segregate in a 2∶2 ratio (asterisk). In contrast, gene conversion will result in a 3∶1 segregation ratio (arrow). (C) A monochrome image with the exposure and contrast globally increased using Photoshop enables easier visualization of the non-fluorescent pollen grains in the tetrads.</p

Deep Genome-Wide Measurement of Meiotic Gene Conversion Using Tetrad Analysis in <em>Arabidopsis thaliana</em>

<div><p>Gene conversion, the non-reciprocal exchange of genetic information, is one of the potential products of meiotic recombination. It can shape genome structure by acting on repetitive DNA elements, influence allele frequencies at the population level, and is known to be implicated in human disease. But gene conversion is hard to detect directly except in organisms, like fungi, that group their gametes following meiosis. We have developed a novel visual assay that enables us to detect gene conversion events directly in the gametes of the flowering plant <em>Arabidopsis thaliana</em>. Using this assay we measured gene conversion events across the genome of more than one million meioses and determined that the genome-wide average frequency is 3.5×10⁻⁴ conversions per locus per meiosis. We also detected significant locus-to-locus variation in conversion frequency but no intra-locus variation. Significantly, we found one locus on the short arm of chromosome 4 that experienced 3-fold to 6-fold more gene conversions than the other loci tested. Finally, we demonstrated that we could modulate conversion frequency by varying experimental conditions.</p> </div

Meiotic recombination models.

<p>The Watson and Crick strands (red and green lines) for two of the four chromatids present at meiosis are shown. Recombination is (a) initiated by SPO11 (blue ovals) catalyzed breaks in one chromatid followed by (b) release of SPO11 and further resection to generate single-stranded 3′ tails. One tail (c) invades a non-sister chromatid to form a D-loop and (d) the invading strand can be extended by DNA polymerase (hatched lines). The Double Strand Break Repair (DSBR, left) pathway proceeds with (e) the D-loop capturing the second 3′ end which is also extended by DNA polymerase. Ligation of the available ends (f) generates a double Holliday Junction which is can be resolved (g) as a crossover with associated regions of heteroduplex DNA (asterisks). Alternatively in Synthesis Dependent Strand Annealing (SDSA, right) the invading strand can dissociate from the homologous chromatid prior to second end capture (h) and re-anneal to the 3′ end on the other side of the break. Gap synthesis and ligation (i) will produce a non-crossover with associated heteroduplex DNA (asterisk).</p

Genome-wide conversion frequencies.

*<p>Adjusted frequencies double the number of observed 3∶1 tetrads to account for 1∶3 tetrads.</p