Loss of vacuolar acidity results in iron-sulfur cluster defects and divergent homeostatic responses during aging in Saccharomyces cerevisiae

The loss of vacuolar/lysosomal acidity is an early event during aging that has been linked to mitochondrial dysfunction. However, it is unclear how loss of vacuolar acidity results in age-related dysfunction. Through unbiased genetic screens, we determined that increased iron uptake can suppress the mitochondrial respiratory deficiency phenotype of yeast vma mutants, which have lost vacuolar acidity due to genetic disruption of the vacuolar ATPase proton pump. Yeast vma mutants exhibited nuclear localization of Aft1, which turns on the iron regulon in response to iron-sulfur cluster (ISC) deficiency. This led us to find that loss of vacuolar acidity with age in wild-type yeast causes ISC defects and a DNA damage response. Using microfluidics to investigate aging at the single-cell level, we observe grossly divergent trajectories of iron homeostasis within an isogenic and environmentally homogeneous population. One subpopulation of cells fails to mount the expected compensatory iron regulon gene expression program, and suffers progressively severe ISC deficiency with little to no activation of the iron regulon. In contrast, other cells show robust iron regulon activity with limited ISC deficiency, which allows extended passage and survival through a period of genomic instability during aging. These divergent trajectories suggest that iron regulation and ISC homeostasis represent a possible target for aging interventions.

Rb analog Whi5 regulates G1 to S transition and cell size but not replicative lifespan in budding yeast

An increase in cell size with age is a characteristic feature of replicative aging in budding yeast. Deletion of the gene encoding Whi5 results in shortened duration of G1 and reduced cell size, and has been previously suggested to increase replicative lifespan. Upon careful analysis of multiple independently derived haploid and homozygous diploid whi5Δ mutants, we find no effect on lifespan, but we do confirm the reduction in cell size. We suggest that instead of antagonizing lifespan, the elongated G1 phase of the cell cycle during aging may actually play an important role in allowing aged cells time to repair accumulating DNA damage.

Can the number of surgery delays and postponements due to unavailable instrumentation be reduced? Evaluating the benefits of enhanced collaboration between the sterilization and orthopedic surgery units

INTRODUCTION

The development of outpatient surgery, cost-reduction pressures and instrumentation storage limitations have led to their use "just-in-time". A recent study showed that stoppage of surgical procedures immediately before the incision (No-Go) was often due to the management of supplies and implantable medical devices. To our knowledge, since the development of outpatient surgery and the shortening of hospital stays, managing the flow of instrumentation has not been optimized. At our hospital, we used a two-prong approach consisting of a tool to manage instrumentation and working group from the sterilization and orthopedic surgery units. The aims of this study were to: 1) evaluate whether this approach led to better notification of the risk of supply shortage for instrumentation and 2) determine whether it could reduce by at least half operating room disruptions such as delays or cancellation of surgical procedures.

HYPOTHESIS

This approach results in better notification of the risk of supply shortage for instrumentation and reduces by at least half operating room disruptions such as delays or cancellation of surgical procedures.

MATERIAL AND METHODS

A tool was developed to manage instrumentation flow based on a retrospective analysis of data from 2015. This tool consisted of: (1) a list of instrumentation needed for each surgical procedure from an analysis of the surgical schedule and verification of traceability labels of the instrumentation actually used, (2) a list of reasons for supply shortage identified from an analysis of non-conformities occurring in the sterilization process of instrumentation kits. These analyses resulted in the development of checklists for instrument sets for each procedure, while identifying those with a high risk of shortage. In 2017, a working group focused on instrumentation was set up with personnel from the sterilization unit and the orthopedic surgery unit. Based on the check-lists and the schedule 24hours before the surgery, the sterilization unit alerted the surgery unit by email of the risk of material shortage; the surgery ward replied with potential changes to the material or the surgery planning. This approach (instrumentation management tool and working group) was named just-in-time (JIT). The main outcome was the number of notifications of potential supply shortage with and without JIT over a 10-week period. The secondary outcomes were the number of notifications resolved in time and the occurrence of operating room disruptions (delay>30min or postponement of surgery) related to unavailable instrumentation.

RESULTS

Nine reasons for potential supply shortage were identified such as instrumentation kits used for several types of procedures, those with fast rotation and low stock, or in double pathways (on loan and on deposit). The working group reported 163 potential shortages with JIT versus 41 without (p<10^-5), of which 150 (92.5%) were resolved. Thirteen operating room disruptions occurred; only one was not detected by the JIT approach.

CONCLUSION

Our JIT approach (instrumentation management tool and working group) is effective at preventing instrumentation supply shortages.

LEVEL OF EVIDENCE

III, prospective comparative study.

Circulating tumor cells monitored over time in lung cancer patients

11025

Background: Circulating tumor cell (CTC) detection and enumeration is a valuable tool for monitoring cancer patient status and outcome. While many current techniques employ immunomagnetic-enrichment based protocols focused on the importance of a particular CTC number as the indicator of patient status or outcome, we employ a cytometric, enrichment free approach using an immunofluorescent protocol to monitor CTC counts in patients with non-small cell lung cancer (NSCLC) over the course of treatment. Methods: Eligible patients had progressive stage IV NSCLC. The histological subtypes in the 42 cases for which the data was available included adenocarcinoma (22/42), squamous cell carcinoma (6/42), large cell undifferentiated carcinoma (3/42), and non-small cell lung carcinoma not further described, poorly differentiated, or with a mixed pattern (11/42). Blood samples were collected 3 wks, 3 mo, 6 mo, 9 mo, and 1 yr after the initial sample. CTCs were identified via immunofluorescence and cytometric analysis. Patient response to therapy was determined by RECIST every 3 months between time 0 and time 12 mo. Results: 80 of 109 patient samples have CTCs (73%) and all of the 52 patients tested have CTCs. 13 of 52 patients have CTC data for time 0 and 3 wks. Only 4 of these patients (30.8%) show a correlation linking CTC count change between time 0 and 3 wks and clinical assessment. 13 patients have CTC data for time 0 and 3 mo, 10 of whom show a correlation linking CTC count change between time 0 and 3 mo and clinical assessment. 7 of the 8 patients (87.5%) showing stable or partial response at 3 mo show a decrease in CTC count between time 0 and 3 mo. Five of the 6 patients (83.3%) clinically showing progressive disease at the 3 mo time point show an increase in CTC count between time 0 and 3 mo. The patients that do not show a correlation linking CTC count change between time 0 and 3 mo and clinical assessment at 3 mo show a correlation at the 6 mo time point. Conclusions: CTCs can be effectively enumerated in metastatic NSCLC patients, with the majority demonstrating CTCs in the setting of progressive disease. The change in CTC count at 3 mo, but not at 3 wks, correlates with radiographic response to chemotherapy. Further follow-up will determine the predictive value of CTC enumeration on survival.

No significant financial relationships to disclose.