Trapped topoisomerase II initiates formation of de novo duplications via the nonhomologous end-joining pathway in yeast.

Topoisomerase II (Top2) is an essential enzyme that resolves catenanes between sister chromatids as well as supercoils associated with the over- or under-winding of duplex DNA. Top2 alters DNA topology by making a double-strand break (DSB) in DNA and passing an intact duplex through the break. Each component monomer of the Top2 homodimer nicks one of the DNA strands and forms a covalent phosphotyrosyl bond with the 5' end. Stabilization of this intermediate by chemotherapeutic drugs such as etoposide leads to persistent and potentially toxic DSBs. We describe the isolation of a yeast top2 mutant (top2-F1025Y,R1128G) the product of which generates a stabilized cleavage intermediate in vitro. In yeast cells, overexpression of the top2-F1025Y,R1128G allele is associated with a mutation signature that is characterized by de novo duplications of DNA sequence that depend on the nonhomologous end-joining pathway of DSB repair. Top2-associated duplications are promoted by the clean removal of the enzyme from DNA ends and are suppressed when the protein is removed as part of an oligonucleotide. TOP2 cells treated with etoposide exhibit the same mutation signature, as do cells that overexpress the wild-type protein. These results have implications for genome evolution and are relevant to the clinical use of chemotherapeutic drugs that target Top2.

A pilot study to precisely quantify forces applied by sonographers while scanning: A step toward reducing ergonomic injury.

BACKGROUND: There is a significantly high rate of work-related musculsokeletal injuries in sonography professionals. To date, assessment of risk factors for work- related injuries in sonographers has been based primarily on surveys, subjective reports, and observational methods. There is a need to develop quantitative techniques to better understand risk factors and develop preventive interventions. OBJECTIVE: We pilot tested a high-resolution force-measuring probe capable of precisely measuring forces applied through the transducer by sonographers and used this novel direct measurement technique to evaluate forces during abdominal imaging. METHODS: Twelve sonographers with varied experience, ranging from 1-33 years, performed routine abdominal scans on 10 healthy volunteers who had varied body mass indices (BMI). Imaging was conducted using the force-measuring probe, which provided real-time measurement of forces, and angles. Data were compared by sonographer years of experience and subject BMI. RESULTS: In total, 47 abdominal examinations were performed as part of this study, and all images met standards for clinical diagnostic quality. The mean contact force applied across all exams was 8.2±4.3 Newtons (N) (range: 1.2-36.5 N). For subjects in the high BMI group (BMI>25, n = 4) the mean force was 10.5 N (range: 8.9-13.2 N) compared to 7.9 N (range: 5.9-10.9 N) for subjects with normal BMI (BMI = 18.5-25, n = 6). Similarly, the mean maximum force applied for subjects with high BMI (25.3 N) was significantly higher than force applied for subjects with normal BMI (17.4 N). No significant difference was noted in the amount of force applied by sonographers with more than 5 years of experience (n = 6) at 8.2 N (Range: 5.1-10.0 N) compared to less experienced sonographers (n = 6), whose forces averaged 8.1 N (Range: 5.8-10.0 N). CONCLUSIONS: It is feasible to directly measure forces applied by sonographers using a high-resolution force measurement system. Forces applied during abdominal imaging vary widely, are significantly higher when scanning subjects with high BMI, and are not related to sonographer years of experience. This force measurement system has the potential to provide an additional quantitative data point to explore the impact of applied forces on sonographer related musculoskeletal injury, particularly in conjunction with various body positions, exam types and force durations.

Effects of an unusual poison identify a lifespan role for Topoisomerase 2 in Saccharomyces cerevisiae.

A progressive loss of genome maintenance has been implicated as both a cause and consequence of aging. Here we present evidence supporting the hypothesis that an age-associated decay in genome maintenance promotes aging in Saccharomyces cerevisiae (yeast) due to an inability to sense or repair DNA damage by topoisomerase 2 (yTop2). We describe the characterization of LS1, identified in a high throughput screen for small molecules that shorten the replicative lifespan of yeast. LS1 accelerates aging without affecting proliferative growth or viability. Genetic and biochemical criteria reveal LS1 to be a weak Top2 poison. Top2 poisons induce the accumulation of covalent Top2-linked DNA double strand breaks that, if left unrepaired, lead to genome instability and death. LS1 is toxic to cells deficient in homologous recombination, suggesting that the damage it induces is normally mitigated by genome maintenance systems. The essential roles of yTop2 in proliferating cells may come with a fitness trade-off in older cells that are less able to sense or repair yTop2-mediated DNA damage. Consistent with this idea, cells live longer when yTop2 expression levels are reduced. These results identify intrinsic yTop2-mediated DNA damage as potentially manageable cause of aging.

Improving Data, Enhancing Enrollment: Florida Covering Kids & Families CHIPRA Data System.

PURPOSE: According to the Kaiser Family Foundation (2014), 502,866 (11.7 %) of Florida children under 19 years of age are uninsured, giving Florida the second largest number of uninsured children in the United States. Florida Covering Kids & Families (FL-CKF) is dedicated to developing innovative outreach methods for enrolling and retaining eligible children in Florida KidCare, the state's Children's Health Insurance Program. FL-CKF has developed a strong data system that allows it to evaluate the effectiveness and success of statewide enrollment and retention efforts. DESCRIPTION: The data system was created using the Checkbox survey systems. Community and school outreach partners enter data each month on all completed Florida KidCare applications via a secure interface. The system requires data be entered in a uniform format and forces vital data points to be completed. These data are then transmitted to the state to obtain timely application determination information on enrollments. ASSESSMENT: The data system helps FL-CKF to determine which outreach strategies are successful and where changes need to be made to increase effectiveness. The system also provides feedback to community outreach partners in order to enable follow up with families when needed. CONCLUSION: Organizations helping uninsured children apply for health insurance may benefit from creating data collection systems to monitor project efficacy and modify outreach and enrollment strategies for greater effectiveness.

Force-controlled ultrasound to measure passive mechanical properties of muscle in Duchenne muscular dystrophy.

The purpose of this study is to assess differences in skeletal muscle compressibility between patients with Duchenne muscular dystrophy (DMD) and normal subjects. The transverse passive mechanical properties of muscle, particularly those related to stiffness and elasticity, can be measured using force-controlled ultrasound. We acquired ultrasound videos of muscle compression under known pressures in the biceps and quadriceps in 23 boys with DMD and 20 age-matched healthy controls. We calculated the bulk linear spring constant, nonlinear stress-strain response, and average Young's modulus for each. Young's modulus was found to be significantly higher in the DMD population in both the biceps (normal: 33 ± 6 kPa, DMD: 45 ± 14, p <; .01) and quadriceps (normal: 42 ± 6, DMD: 58 ± 14, p <; .0001). Muscle compressibility measured by force-controlled ultrasound is an objective and robust technique to quantitatively monitor the effects of DMD and distinguish from normal subjects.

Probe localization for freehand 3D ultrasound by tracking skin features.

Ultrasound probe localization with respect to the patient's body is essential for freehand three-dimensional ultrasound and image-guided intervention. However, current methods for probe localization generally involve bulky and expensive equipment. In this paper, a highly cost-effective and miniature-mobile system is described for 6-DoF probe localization that is robust to rigid patient motion. In this system, skin features in the scan region are recorded at each ultrasound scan acquisition by a lightweight camera rigidly mounted to the probe. A skin map is built based on the skin features and optimal probe poses are estimated in a Bayesian probabilistic framework that incorporates a prior motion model, camera frames, and ultrasound scans. Through freehand scanning on three different body parts, it is shown that on average, for every probe travel distance of 10 mm, the translational and rotational errors are 0.91 ± 0.49 mm and 0.55 degrees ± 0.17 degrees, respectively. The 3D reconstructions were also validated by comparison with real ultrasound scans.

An ergonomic, instrumented ultrasound probe for 6-axis force/torque measurement.

An ergonomic, instrumented ultrasound probe has been developed for medical imaging applications. The device, which fits compactly in the hand of sonographers and permits rapid attachment & removal of the ultrasound probe, measures ultrasound probe-to-patient contact forces and torques in all six axes. The device was used to measure contact forces and torques applied by ten professional sonographers on five patients during thirty-six abdominal exams. Of the three contact forces, those applied along the probe axis were found to be largest, averaging 7.0N. Measurement noise was quantified for each axis, and found to be small compared with the axial force. Understanding the range of forces applied during ultrasound imaging enables the design of more accurate robotic imaging systems and could also improve understanding of the correlation between contact force and sonographer fatigue and injury.

The bottleneck effect in lung cancer clinical trials.

Clinical trials provide the most promising way to improve treatment outcomes in cancer. This study examined the rate at which eligible patients with lung cancer, at a National Cancer Institute-designated cancer center in the South, were offered a clinical trial and explored for reasons for ineligibility. We retrospectively reviewed 300 randomly selected lung cancer patients' medical records seen in 2010, to assess clinical trial offers to eligible patients, reasons for not offering an eligible patient a trial, demographic factors associated with eligibility, and reasons for refusal among those offered a trial. Of the 300 patient charts, seven were excluded for lack of confirmed lung cancer diagnosis. Forty-six of the remaining 293 (15.7%) patients were eligible for a clinical trial. Forty-five of the 46 (97.8%) were considered for a trial by their oncologist. Thirty-five of the 45 (77.8%) were offered a trial: 15 agreed (42.9% of those offered, 5.1% of patients reviewed), 11 declined, and 9 were undecided at the end of the review window. Patients with poor Eastern Cooperative Oncology Group (ECOG) performance status levels and small cell (SC) diagnoses were significantly less likely to be eligible for a trial. Results suggest that oncologists at the cancer center are effectively presenting all eligible patients with the option of a clinical trial; however, there is a need to increase the number of approved clinical trials for patients with SC or ECOG score greater than 2.