Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

A mitotic topoisomerase II checkpoint in budding yeast is required for genome stability but acts independently of Pds1/securin

Topoisomerase II (Topo II) performs topological modifications on double-stranded DNA molecules that are essential for chromosome condensation, resolution, and segregation. In mammals, G2 and metaphase cell cycle delays induced by Topo II poisons have been proposed to be the result of checkpoint activation in response to the catenation state of DNA. However, the apparent lack of such controls in model organisms has excluded genetic proof that Topo II checkpoints exist and are separable from the conventional DNA damage checkpoint controls. But here, we define a Topo II-dependent G2/M checkpoint in a genetically amenable eukaryote, budding yeast, and demonstrate that this checkpoint enhances cell survival. Conversely, a lack of the checkpoint results in aneuploidy. Neither DNA damage-responsive pathways nor Pds1/securin are needed for this checkpoint. Unusually, spindle assembly checkpoint components are required for the Topo II checkpoint, but checkpoint activation is not the result of failed chromosome biorientation or a lack of spindle tension. Thus, compromised Topo II function activates a yeast checkpoint system that operates by a novel mechanism

Direct Monitoring of the Strand Passage Reaction of DNA Topoisomerase II Triggers Checkpoint Activation

<div><p>By necessity, the ancient activity of type II topoisomerases co-evolved with the double-helical structure of DNA, at least in organisms with circular genomes. In humans, the strand passage reaction of DNA topoisomerase II (Topo II) is the target of several major classes of cancer drugs which both poison Topo II and activate cell cycle checkpoint controls. It is important to know the cellular effects of molecules that target Topo II, but the mechanisms of checkpoint activation that respond to Topo II dysfunction are not well understood. Here, we provide evidence that a checkpoint mechanism monitors the strand passage reaction of Topo II. In contrast, cells do not become checkpoint arrested in the presence of the aberrant DNA topologies, such as hyper-catenation, that arise in the absence of Topo II activity. An overall reduction in Topo II activity (i.e. slow strand passage cycles) does not activate the checkpoint, but specific defects in the T-segment transit step of the strand passage reaction do induce a cell cycle delay. Furthermore, the cell cycle delay depends on the divergent and catalytically inert C-terminal region of Topo II, indicating that transmission of a checkpoint signal may occur via the C-terminus. Other, well characterized, mitotic checkpoints detect DNA lesions or monitor unattached kinetochores; these defects arise <i>via</i> failures in a variety of cell processes. In contrast, we have described the first example of a distinct category of checkpoint mechanism that monitors the catalytic cycle of a single specific enzyme in order to determine when chromosome segregation can proceed faithfully.</p></div

Analysis of G2/M Cell Cycle Checkpoint Activation in <i>top2</i> Mutants.

<p><b>a–c</b>, Population Assays: kinetics of cell cycle progression based on budding (DIC microscopy) and spindle morphology (Tub1-GFP). Cell populations were returned to growth after depletion of Top2^deg and synchronization in G1 (alpha-factor). The interval between spindle assembly and anaphase (<i>a</i>, arrow) is not significantly different with wild-type endogenously expressed <i>TOP2</i> or after Top2^deg degradation in G1. Panel <i>b</i> shows overlaid repetitions of each experiment to assess variation (green/blue/purple, indicate three experimental repeats). Panel <i>c</i>, histogram plot of average G2/M duration; see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003832#s3" target="_blank">Material and Methods</a> for statistical analysis. <b>d–f</b>, Single-cell Assays: kinetics of spindle assembly and elongation in single cells based on digital time-lapse microscopy of strains expressing Tub1-GFP. Images in panel <i>d</i> show representative images of each morphological state (also see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003832#pgen.1003832.s011" target="_blank">Movie S1</a>). Panel <i>e</i>, plot of average spindle length (or SPB diameter; first five time points) versus time for single cells aligned on the x-axis at the time of SPB separation (<i>i.e.</i> at time point 12 min). Standard deviation of lengths shows that SPB diameter and G2 spindle length are relatively constant. Standard deviation of spindle length increases markedly as some cells enter anaphase. Panel <i>f</i>, plots average time interval between SPB separation and the initiation of spindle elongation in anaphase B (+/− s.e.).</p

Defective T-Segment Transit may Activate the Mad2-Dependent Checkpoint.

<p>Cell cycle analyses showing that Top2^L475A,L480P activates Mad2-dependent but Rad53-independent checkpoint signaling. <b>a</b>, Cartoon describing catalytic defect in Top2^L475A,L480P which has a reduced rate of T-segment transport due to inefficient G-segment cleavage and DNA-gate opening. <b>b–d</b>, Population Assays: Histogram plots show average G2/M duration; see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003832#s3" target="_blank">Material and Methods</a> for statistical analysis. Western blots show each Top2 mutant relative to Tub1 loading control at G1 and G2. <i>a</i> values are significantly different to <i>b</i> values in the histogram plots. Strains with the same letter are not significantly different. <b>e–f</b>, Single-cell assays: <i>e</i>, plots of average spindle length versus time for single cells aligned on the x-axis at the time of SPB separation (<i>i.e.</i> at time point 12 min). Error bars show standard deviation of lengths. <i>f</i>, Histogram plots of average time interval between SPB separation and the initiation of spindle elongation in anaphase B (+/− s.e.).</p

Checkpoint Activation <i>via</i> Top2-B44 Requires Initiation of the Strand Passage Reaction.

<p><b>a</b>, Cartoon describing the catalytic defect in Top2^Y782F which cannot cleave G-segment DNA and thus performs non-productive cycles of ATP hydrolysis and N-gate closure/opening (see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003832#pgen-1003832-g001" target="_blank">Figure 1</a> for complete Strand Passage Reaction and Key). <b>b–d</b>, Analysis of the kinetics of cell cycle progression (see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003832#pgen-1003832-g003" target="_blank">Figure 3</a>) following depletion of Top2^deg and release from G1 synchrony in cells expressing endogenous levels of the indicated mutant Top2 proteins. <b>b</b>, Population Assays: Histogram plots show average G2/M duration; see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003832#s3" target="_blank">Material and Methods</a> for statistical analysis. Western blots show each Top2 mutant relative to Tub1 loading control at G1 and G2. <i>a</i> values are significantly different to <i>b</i> values in the histogram plots. Strains with the same letter are not significantly different. <b>c–d</b>, Single-cell assays: <i>c</i>, plots of average spindle length versus time for single cells aligned on the x-axis at the time of SPB separation (<i>i.e.</i> at time point 12 min). Error bars show standard deviation of lengths. <i>d</i>, Histogram plots of average time interval between SPB separation and the initiation of spindle elongation in anaphase B (+/− s.e.).</p

Slow Strand Passage does not Activate the Mad2-Dependent Checkpoint in the Absence of a T-Segment Transit Defect.

<p>Analysis of cell cycle kinetics in <i>top2</i>^deg strains expressing Top2^G738D and Top2^P824S which have overall reduced rates of the catalytic cycle do not activate checkpoint signaling. <b>a</b>, Population Assays: Histogram plots show average G2/M duration; see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003832#s3" target="_blank">Material and Methods</a> for statistical analysis. Western blots show each Top2 mutant relative to Tub1 loading control at G1 and G2. <i>a</i> values are significantly different to <i>b</i> values in the histogram plots. Strains with the same letter are not significantly different. <b>b–c</b>, Single-cell assays: <i>b</i>, plots of average spindle length versus time for single cells aligned on the x-axis at the time of SPB separation (<i>i.e.</i> at time point 12 min). Error bars show standard deviation of lengths. <i>c</i>, Histogram plots of average time interval between SPB separation and the initiation of spindle elongation in anaphase B (+/− s.e.).</p

Defective Top2 ATP Binding and Hydrolysis Activate the Mad2-Depedent Checkpoint.

<p><b>a</b>, Cartoon describing catalytic defects in Top2^G144I which cannot bind ATP (green annotations) and Top2^E66Q which cannot hydrolyze ATP (blue annotations). (See <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003832#pgen-1003832-g001" target="_blank">Figure 1</a> for complete Strand Passage Reaction and Key). <b>b–j</b>, Cell cycle analyses showing that Top2^G144I and Top2^E66Q activate Mad2-dependent but Rad53-independent checkpoint signaling. Analysis of the kinetics of cell cycle progression (see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003832#pgen-1003832-g003" target="_blank">Figure 3</a>) following depletion of Top2^deg and release from G1 synchrony in cells expressing endogenous levels of the indicated mutant Top2 proteins. (b–h) Population Assays: Histogram plots show average G2/M duration; see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003832#s3" target="_blank">Material and Methods</a> for statistical analysis. Western blots show each Top2 mutant relative to Tub1 loading control at G1 and G2. <i>a</i> values are significantly different to <i>b</i> values in the histogram plots. Strains with the same letter are not significantly different. (i,j) Single-cell assays: <i>i</i>, plots of average spindle length versus time for single cells aligned on the x-axis at the time of SPB separation (<i>i.e.</i> at time point 12 min). Error bars show standard deviation of lengths. <i>j</i>, Histogram plots of average time interval between SPB separation and the initiation of spindle elongation in anaphase B (+/− s.e.).</p