Robust spatiotemporal organization of mitotic events in mechanically perturbed C. elegans embryos

Early embryogenesis of the nematode Caenorhabditis elegans progresses in an autonomous fashion within a protective chitin eggshell. Cell-division timing and the subsequent mechanically guided positioning of cells is virtually invariant between individuals, especially before gastrulation. Here, we have challenged this stereotypical developmental program in early stages by mechanically perturbing the embryo without breaking its eggshell. Compressing embryos to about two-thirds of their unperturbed diameter only resulted in markedly slower cell divisions. In contrast, compressing embryos to half of their native diameter frequently resulted in a loss of cytokinesis, yielding a non-natural syncytium that still allowed for multiple divisions of nuclei. Although the orientation of mitotic axes was strongly altered in the syncytium, key features of division timing and spatial arrangement of nuclei remained surprisingly similar to those of unperturbed embryos in the first few division cycles. This suggests that few, very robust mechanisms provide a basic and resilient program for safeguarding the early embryogenesis of C. elegans.

Molecular Crowding: The History and Development of a Scientific Paradigm

It is now generally accepted that macromolecules do not act in isolation but "live" in a crowded environment, that is, an environment populated by numerous different molecules. The field of molecular crowding has its origins in the far 80s but became accepted only by the end of the 90s. In the present issue, we discuss various aspects that are influenced by crowding and need to consider its effects. This Review is meant as an introduction to the theme and an analysis of the evolution of the crowding concept through time from colloidal and polymer physics to a more biological perspective. We introduce themes that will be more thoroughly treated in other Reviews of the present issue. In our intentions, each Review may stand by itself, but the complete collection has the aspiration to provide different but complementary perspectives to propose a more holistic view of molecular crowding.

Long-Term Follow-Up of the RESORT Study (E4402): A Randomized Phase III Comparison of Two Different Rituximab Dosing Strategies for Low-Tumor Burden Follicular Lymphoma

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical trial updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.In 2003, the Eastern Cooperative Oncology Group initiated a randomized phase III clinical trial (E4402) comparing two different rituximab dosing strategies for patients with previously untreated low-tumor burden follicular lymphoma. Rituximab-responsive patients (n = 299) were randomly assigned to either a retreatment rituximab (RR) strategy or a maintenance rituximab (MR) strategy. Each dosing strategy was continued until treatment failure. The primary end point of the study was time to treatment failure (TTF). In the original report, there was no difference in TTF between the two dosing strategies. Here, we report on the long-term outcomes for secondary end points of time to first cytotoxic therapy, duration of response, and overall survival (OS). At 7 years, 83% of MR patients had not required first chemotherapy compared with 63% of RR patients (hazard ratio, 2.37 [95% CI, 1.5 to 3.76]). At 7 years, 71% of MR remained in their first remission compared with 37% of RR patients. Despite the improved first remission length with MR, there was no difference in OS at 10 years (83% v 84%). With mature long-term data, we confirm that prolonged maintenance rituximab does not confer an OS advantage in low-tumor burden follicular lymphoma.

Microtubule polyglutamylation is an essential regulator of cytoskeletal integrity in Trypanosoma brucei

Tubulin polyglutamylation, catalysed by members of the tubulin tyrosine ligase-like (TTLL) protein family, is an evolutionarily highly conserved mechanism involved in the regulation of microtubule dynamics and function in eukaryotes. In the protozoan parasite Trypanosoma brucei, the microtubule cytoskeleton is essential for cell motility and maintaining cell shape. In a previous study, we showed that T. brucei TTLL6A and TTLL12B are required to regulate microtubule dynamics at the posterior cell pole. Here, using gene deletion, we show that the polyglutamylase TTLL1 is essential for the integrity of the highly organised microtubule structure at the cell pole, with a phenotype distinct from that observed in TTLL6A- and TTLL12B-depleted cells. Reduced polyglutamylation in TTLL1-deficient cells also leads to increased levels in tubulin tyrosination, providing new evidence for an interplay between the tubulin tyrosination and detyrosination cycle and polyglutamylation. We also show that TTLL1 acts differentially on specific microtubule doublets of the flagellar axoneme, although the absence of TTLL1 appears to have no measurable effect on cell motility.

Non-surgical external jugular vein catheterization using an ear vein access in piglets

The objective of this study was to investigate the feasibility of external jugular vein catheterization through an ear vein in piglets. Forty-six sevoflurane-midazolam anaesthetized piglets were included. External jugular vein catheterization was conducted through the ear vein using the Seldinger technique. Part 1 (n = 27): optimal puncture site was based on the deltoid tuberosity as a landmark to reach the external jugular vein. The final position of the catheter was verified in 25 piglets using computer tomography. Catheterization time was recorded and patency of the catheter assessed by repeated blood sampling for up to 4 h. Part 2 (n = 19): ear vein catheterization was without taking into account any landmarks. Functionality for blood sampling was evaluated as described in part 1. Catheter advancement was possible in 25/27 and 18/19 piglets in parts 1 and 2, respectively. Median (range) time required for successful catheterization was 1.95 (1-10) min (n = 38). The deltoid tuberosity was a good landmark to reach the external jugular vein. But blood sampling was also possible through catheters ending slightly cranial to the external jugular vein. Despite successful catheter advancement, blood sampling was not possible from one catheter in each part of the study (total: two piglets). One of these catheters presented luminal damage, while the other one presented as normal after being removed from the animal. Summarizing, central vein catheterization through the ear vein was feasible in 93.5% and repeated blood sampling was possible in 89.1% of the piglets (n = 46).

End-of-life practices in 11 German intensive care units : Results from the ETHICUS-2 study

BACKGROUND

End-of-life care is common in German intensive care units (ICUs) but little is known about daily practice.

OBJECTIVES

To study the practice of end-of-life care.

METHODS

Prospectively planned, secondary analysis comprising the German subset of the worldwide Ethicus‑2 Study (2015-2016) including consecutive ICU patients with limitation of life-sustaining therapy or who died.

RESULTS

Among 1092 (13.7%) of 7966 patients from 11 multidisciplinary ICUs, 967 (88.6%) had treatment limitations, 92 (8.4%) died with failed CPR, and 33 (3%) with brain death. Among patients with treatment limitations, 22.3% (216/967) patients were discharged alive from the ICU. More patients had treatments withdrawn than withheld (556 [57.5%] vs. 411 [42.5%], p < 0.001). Patients with treatment limitations were older (median 73 years [interquartile range (IQR) 61-80] vs. 68 years [IQR 54-77]) and more had mental decision-making capacity (12.9 vs. 0.8%), advance directives (28.6 vs. 11.2%), and information about treatment wishes (82.7 vs 33.3%, all p < 0.001). Physicians reported discussing treatment limitations with patients with mental decision-making capacity and families (91.3 and 82.6%, respectively). Patient wishes were unknown in 41.3% of patients. The major reason for decision-making was unresponsiveness to maximal therapy (34.6%).

CONCLUSIONS

Treatment limitations are common, based on information about patients' wishes and discussion between stakeholders, patients and families. However, our findings suggest that treatment preferences of nearly half the patients remain unknown which affects guidance for treatment decisions.

Initial Results of a Phase II Trial of Hypofractionated Radiation Therapy for Inoperable Soft Tissue Sarcoma

PURPOSE/OBJECTIVE(S)

For patients with soft tissue sarcoma (STS) who cannot or choose not to have surgery, radiation can provide local tumor control in both palliative and definitive settings. Conventionally fractionated radiation provides modest (< 50%) rates of local control (LC) for STS at 2 years. To our knowledge, no prospective studies to date have evaluated the safety and efficacy of dose-escalated hypofractionated radiation therapy as treatment of inoperable STS. We hypothesized that dose-escalated, hypofractionated radiation therapy (RT) for inoperable STS could achieve higher rates of LC than reported in trials of conventionally fractionated RT.

MATERIALS/METHODS

An IRB-approved single institution prospective phase II clinical trial of dose-escalated, hypofractionated RT as local control for STS was designed and completed planned accrual. Exclusion criteria included anti-cancer systemic therapy within the preceding two weeks. Patients underwent hypofractionated RT utilizing either CT-guided radiation (24, 50%) or MRI-guided radiation treatments (24, 50%). Data on patient characteristics, RT dose and fractionation, LC, toxicity, and overall survival (OS) was collected. The primary endpoint was local tumor control (stable, partial, or complete response according to RECIST) at 2-years after completion of radiation. Secondary endpoints were acute and late toxicity, rates of complete response, 5-year local tumor control, and progression-free and overall survival. Acute toxicity was graded on the Common Terminology Criteria for Adverse Events (CTCAE) v5.0 scale during treatment and at 3 months following RT.

RESULTS

Forty-eight patients were enrolled, 17 with non-metastatic localized disease and 31 with metastatic disease. Median patient age was 64. Twenty-five men and 23 women were treated. Ninety-six total lesions were treated (36 lung, 7 extremity, 37 abdominopelvic, 16 other). Radiation dose per fraction ranged from 6-12 Gy for a total of 1-12 fractions (median dose was 52.5 Gy in 6 fractions. Median patient follow-up is 8.6 months (range 1 - 36 months). Six patients (13%) did not complete initial 3-month follow-up imaging. Of the 40 patients who have undergone 3-month follow up imaging, 32 (80%) had stable disease, 5 (12.5%) had partial response, 0 had complete response, and 3 (7.5%) had disease progression. Median PFS was 17.2 months at time of last follow up. Median OS was 12.9 months at time of last follow up. Twenty-five patients (52%) experienced an acute toxicity likely or possibly related to radiation. Three (6%) patients experienced CTACE grade 3 or greater treatment-related toxicity (pain, weakness, decreased range of motion, dermatitis).

CONCLUSION

In this initial report of a prospective, single-institution clinical trial of hypofractionated RT for STS not undergoing resection, we report low rates of acute grade 3 or greater toxicity and high rates of tumor response. We will continue to follow these patients to assess late toxicity and durability of tumor control.

Healthcare utilization and unmet needs of patients with antisynthetase syndrome: An international patient survey

Antisynthease syndrome (ASSD) is a rare, complex and understudied autoimmune disease. Internet-based studies can overcome barriers of traditional on-site research and are therefore very appealing for rare diseases. The aim of this study was to investigate patient-reported symptoms, diagnostic delay, symptoms, medical care, health status, working status, disease knowledge and willingness to participate in research of ASSD patients by conducting an international web-based survey. The multilingual questionnaire was created by an international group of rheumatologists and patients and distributed online. 236 participants from 22 countries completed the survey. 184/236 (78.0%) were female, mean age (SD) was 49.6 years (11.3) and most common antisynthetase antibody was Jo-1 (169/236, 71.6%). 79/236 (33.5%) reported to work full-time. Median diagnostic delay was one year. The most common symptom at disease onset was fatigue 159/236 (67.4%), followed by myalgia 130/236 (55.1%). The complete triad of myositis, arthritis and lung involvement verified by a clinician was present in 42/236 (17.8%) at disease onset and in 88/236 (37.3%) during the disease course. 36/236 (15.3%) reported to have been diagnosed with fibromyalgia and 40/236 (16.3%) with depression. The most reported immunosuppressive treatments were oral corticosteroids 179/236 (75.9%), followed by rituximab 85/236 (36.0%). 73/236 (30.9%) had received physiotherapy treatment. 71/236 (30.1%) reported to know useful online information sources related to ASSD. 223/236 (94.5%) were willing to share health data for research purposes once a year. Our results reiterate that internet-based research is invaluable for cooperating with patients to foster knowledge in rare diseases.

A Pilot, First in Human Study of Autologous IFN-Gamma Stimulated Mesenchymal Stromal Cells for Treatment of Radiation-Induced Xerostomia

PURPOSE/OBJECTIVE(S)

There are no existing effective treatments for radiation-induced xerostomia (RIX), a common side effect of head and neck radiation. Mesenchymal stromal cells (MSCs) exhibit regenerative effects in multiple tissues and may represent an effective cell therapy for the treatment of RIX. Here we present the primary safety and secondary efficacy endpoints of a first-in-human pilot study of IFNγ-stimulated autologous bone marrow- derived MSCs [MSC(M)] for the treatment of RIX.

MATERIALS/METHODS

We conducted a single-center clinical trial investigating the safety and tolerability of autologous IFNγ-stimulated MSC(M). The study was conducted under an FDA-IND and approved by the local IRB. Patients underwent bone marrow aspiration, MSC(M) were then culture-expanded, stimulated with IFNγ, and cryopreserved. Banked IFNγ-stimulated MSC(M) were thawed, allowed to recover, and then 10 × 106 MSC(M) were injected transcutaneously via ultrasound guidance into one submandibular gland. The primary objective was safety and tolerability determined by dose-limiting toxicity (DLT) defined as submandibular pain > 5 on a standard 10-point pain scale or any serious adverse event (SAE) within one month after injection. Secondary objectives included analysis of efficacy as measured by salivary quantification and using 3 validated quality of life instruments. Quantitative results are reported as mean and standard deviation (SD).

RESULTS

Six radiation-induced xerostomia patients with head and neck cancer who had completed radiation at least 2 years earlier were enrolled. The median age was 71 (61-74) and 5 (83%) patients were male. Five patients (83%) were treated with chemoradiation and one patient (17%) with radiation alone. The average dose of radiation to the injected submandibular gland was 59.9 Gy. Three patients (50%) reported a pain score of 1 after submandibular gland injection, all pain resolved within 4 days. No patients reported pain 1 month after injection, with no SAEs or other DLTs reported 1 month after injection. The analysis of secondary endpoints demonstrated a trend of increased salivary production. The mean unstimulated saliva was 0.13 mL/min (SD 0.17) at baseline and increased to 0.14 mL/min (SD 0.12) at 1 month after injection and 0.19 mL/min (SD 0.21) at 3-months. Quality of life surveys also showed a trend towards improvement.

CONCLUSION

Injection of autologous IFNγ-stimulated MSC(M) into the submandibular gland of patients with RIX is safe and well tolerated. A trend towards an improvement in secondary endpoints of salivary quantity and quality of life was observed. This first-in-human pilot study provides support for further investigation into IFNγ-stimulated MSC(M) as an innovative, potentially curative, remedy to treat RIX. A phase I dose-escalation study injecting into bilateral submandibular glands is scheduled to begin accrual in the spring of 2023.

Phase II trial of hypomethylating agent combined with nivolumab for acute myeloid leukaemia relapse after allogeneic haematopoietic cell transplantation-Immune signature correlates with response

Acute myeloid leukaemia (AML) relapse after allogeneic haematopoietic cell transplantation (allo-HCT) is often driven by immune-related mechanisms and associated with poor prognosis. Immune checkpoint inhibitors combined with hypomethylating agents (HMA) may restore or enhance the graft-versus-leukaemia effect. Still, data about using this combination regimen after allo-HCT are limited. We conducted a prospective, phase II, open-label, single-arm study in which we treated patients with haematological AML relapse after allo-HCT with HMA plus the anti-PD-1 antibody nivolumab. The response was correlated with DNA-, RNA- and protein-based single-cell technology assessments to identify biomarkers associated with therapeutic efficacy. Sixteen patients received a median number of 2 (range 1-7) nivolumab applications. The overall response rate (CR/PR) at day 42 was 25%, and another 25% of the patients achieved stable disease. The median overall survival was 15.6 months. High-parametric cytometry documented a higher frequency of activated (ICOS+ , HLA-DR+ ), low senescence (KLRG1- , CD57- ) CD8+ effector T cells in responders. We confirmed these findings in a preclinical model. Single-cell transcriptomics revealed a pro-inflammatory rewiring of the expression profile of T and myeloid cells in responders. In summary, the study indicates that the post-allo-HCT HMA/nivolumab combination induces anti-AML immune responses in selected patients and could be considered as a bridging approach to a second allo-HCT. Trial-registration: EudraCT-No. 2017-002194-18.

The JAK1/2 inhibitor ruxolitinib in patients with COVID-19 triggered hyperinflammation: the RuxCoFlam trial

Dysregulated hyperinflammatory response is key in the pathogenesis in patients with severe COVID-19 leading to acute respiratory distress syndrome and multiorgan failure. Whilst immunosuppression has been proven to be effective, potential biological targets and optimal timing of treatment are still conflicting. We sought to evaluate efficacy and safety of the Janus Kinase 1/2 inhibitor ruxolitinib, employing the previously developed COVID-19 Inflammation Score (CIS) in a prospective multicenter open label phase II trial (NCT04338958). Primary objective was reversal of hyperinflammation (CIS reduction of ≥25% at day 7 in ≥20% of patients). In 184 patients with a CIS of ≥10 (median 12) ruxolitinib was commenced at an initial dose of 10 mg twice daily and applied over a median of 14 days (range, 2-31). On day 7, median CIS declined to 6 (range, 1-13); 71% of patients (CI 64-77%) achieved a ≥25% CIS reduction accompanied by a reduction of markers of inflammation. Median cumulative dose was 272.5 mg/d. Treatment was well tolerated without any grade 3-5 adverse events related to ruxolitinib. Forty-four patients (23.9%) died, all without reported association to study drug. In conclusion, ruxolitinib proved to be safe and effective in a cohort of COVID-19 patients with defined hyperinflammation.

First Dark Matter Search with Nuclear Recoils from the XENONnT Experiment

We report on the first search for nuclear recoils from dark matter in the form of weakly interacting massive particles (WIMPs) with the XENONnT experiment, which is based on a two-phase time projection chamber with a sensitive liquid xenon mass of 5.9 ton. During the (1.09±0.03)  ton yr exposure used for this search, the intrinsic ^{85}Kr and ^{222}Rn concentrations in the liquid target are reduced to unprecedentedly low levels, giving an electronic recoil background rate of (15.8±1.3)  events/ton yr keV in the region of interest. A blind analysis of nuclear recoil events with energies between 3.3 and 60.5 keV finds no significant excess. This leads to a minimum upper limit on the spin-independent WIMP-nucleon cross section of 2.58×10^{-47}  cm^{2} for a WIMP mass of 28  GeV/c^{2} at 90% confidence level. Limits for spin-dependent interactions are also provided. Both the limit and the sensitivity for the full range of WIMP masses analyzed here improve on previous results obtained with the XENON1T experiment for the same exposure.

The random walker's toolbox for analyzing single-particle tracking data

Technological advances and a burst of new microscopy methods have boosted the use of quantitative tracking experiments, in Soft Matter and Biological Physics but also in the Life Sciences. However, in contrast to highly advanced measurement techniques and tracking tools, subsequent analyses of trajectories frequently do not exploit the data's full potential. Aiming especially at experimental laboratories and early-career scientists, we introduce, discuss, and apply in this Tutorial Review a large set of versatile measures that have proven to be useful for analyzing trajectories from single-particle tracking experiments, beyond a simple extraction of diffusion constants from mean squared displacements. To support a direct test and application of these measures, we supplement the text with a download package that comprises a low-threshold toolbox of ready-to-use routines and training data sets, hence relaxing the need to develop home-brewed solutions and/or to create suitable benchmark data.

Searching for Heavy Dark Matter near the Planck Mass with XENON1T

Multiple viable theoretical models predict heavy dark matter particles with a mass close to the Planck mass, a range relatively unexplored by current experimental measurements. We use 219.4 days of data collected with the XENON1T experiment to conduct a blind search for signals from multiply interacting massive particles (MIMPs). Their unique track signature allows a targeted analysis with only 0.05 expected background events from muons. Following unblinding, we observe no signal candidate events. This Letter places strong constraints on spin-independent interactions of dark matter particles with a mass between 1×10^{12} and 2×10^{17}  GeV/c^{2}. In addition, we present the first exclusion limits on spin-dependent MIMP-neutron and MIMP-proton cross sections for dark matter particles with masses close to the Planck scale.

Exploring generic principles of compartmentalization in a developmental in vitro model

Self-organization of cells into higher-order structures is key for multicellular organisms, for example via repetitive replication of template-like founder cells or syncytial energids. Yet, very similar spatial arrangements of cell-like compartments ('protocells') are also seen in a minimal model system of Xenopus egg extracts in the absence of template structures and chromatin, with dynamic microtubule assemblies driving the self-organization process. Quantifying geometrical features over time, we show here that protocell patterns are highly organized with a spatial arrangement and coarsening dynamics similar to that of two-dimensional foams but without the long-range ordering expected for hexagonal patterns. These features remain invariant when enforcing smaller protocells by adding taxol, i.e. patterns are dominated by a single, microtubule-derived length scale. Comparing our data to generic models, we conclude that protocell patterns emerge by simultaneous formation of randomly assembling protocells that grow at a uniform rate towards a frustrated arrangement before fusion of adjacent protocells eventually drives coarsening. The similarity of protocell patterns to arrays of energids and cells in developing organisms, but also to epithelial monolayers, suggests generic mechanical cues to drive self-organized space compartmentalization.

Dexamethasone to prevent everolimus-induced stomatitis (Alliance MIST Trial: A221701)

mTOR inhibitors such as everolimus may cause oral stomatitis, often a dose-limiting toxicity. Prior clinical research has suggested that a dexamethasone mouth rinse might help prevent and/or treat this. Alliance A221701 was a randomized phase III trial of patients initiating 10 mg daily oral everolimus that compared dexamethasone mouthwash taken preventively (initial dexamethasone group) versus therapeutically (initial placebo group) to assess two coprimary endpoints: the incidence of mTOR inhibitor-associated stomatitis (mIAS), and the area under the curve (AUC) of mIAS-associated pain over an 8-week treatment period. A Fisher's exact test was used to compare the incidences while a Wilcoxon rank-sum test was used to compare the AUCs. In addition, we performed an exploratory analysis of the association of everolimus trough concentrations and toxicity using a Mann-Whitney U test. Due to slow accrual, this study closed after 39 patients were randomized (19 to upfront placebo and 20 to upfront dexamethasone). There were no significant differences between groups seen in either of the coprimary endpoints; furthermore, we found no association between whole blood everolimus trough concentrations and toxicity. Although limited by poor enrollment, the results of this study do not suggest that prophylactic dexamethasone mouthwash is superior to therapeutic dexamethasone mouthwash (initiated at the first sign of mouth pain) for reducing the incidence or severity of mIAS from everolimus.

Extracting, quantifying, and comparing dynamical and biomechanical properties of living matter through single particle tracking

A panoply of new tools for tracking single particles and molecules has led to an explosion of experimental data, leading to novel insights into physical properties of living matter governing cellular development and function, health and disease. In this Perspective, we present tools to investigate the dynamics and mechanics of living systems from the molecular to cellular scale via single-particle techniques. In particular, we focus on methods to measure, interpret, and analyse complex data sets that are associated with forces, materials properties, transport, and emergent organisation phenomena within biological and soft-matter systems. Current approaches, challenges, and existing solutions in the associated fields are outlined in order to support the growing community of researchers at the interface of physics and the life sciences. Each section focuses not only on the general physical principles and the potential for understanding living matter, but also on details of practical data extraction and analysis, discussing limitations, interpretation, and comparison across different experimental realisations and theoretical frameworks. Particularly relevant results are introduced as examples. While this Perspective describes living matter from a physical perspective, highlighting experimental and theoretical physics techniques relevant for such systems, it is also meant to serve as a solid starting point for researchers in the life sciences interested in the implementation of biophysical methods.

Offloading under cognitive load: Humans are willing to offload parts of an attentionally demanding task to an algorithm

In the near future, humans will increasingly be required to offload tasks to artificial systems to facilitate daily as well as professional activities. Yet, research has shown that humans are often averse to offloading tasks to algorithms (so-called "algorithmic aversion"). In the present study, we asked whether this aversion is also present when humans act under high cognitive load. Participants performed an attentionally demanding task (a multiple object tracking (MOT) task), which required them to track a subset of moving targets among distractors on a computer screen. Participants first performed the MOT task alone (Solo condition) and were then given the option to offload an unlimited number of targets to a computer partner (Joint condition). We found that participants significantly offloaded some (but not all) targets to the computer partner, thereby improving their individual tracking accuracy (Experiment 1). A similar tendency for offloading was observed when participants were informed beforehand that the computer partner's tracking accuracy was flawless (Experiment 2). The present findings show that humans are willing to (partially) offload task demands to an algorithm to reduce their own cognitive load. We suggest that the cognitive load of a task is an important factor to consider when evaluating human tendencies for offloading cognition onto artificial systems.

Interplay of Immunosuppression and Immunotherapy Among Patients With Cancer and COVID-19

Importance

Cytokine storm due to COVID-19 can cause high morbidity and mortality and may be more common in patients with cancer treated with immunotherapy (IO) due to immune system activation.

Objective

To determine the association of baseline immunosuppression and/or IO-based therapies with COVID-19 severity and cytokine storm in patients with cancer.

Design, Setting, and Participants

This registry-based retrospective cohort study included 12 046 patients reported to the COVID-19 and Cancer Consortium (CCC19) registry from March 2020 to May 2022. The CCC19 registry is a centralized international multi-institutional registry of patients with COVID-19 with a current or past diagnosis of cancer. Records analyzed included patients with active or previous cancer who had a laboratory-confirmed infection with SARS-CoV-2 by polymerase chain reaction and/or serologic findings.

Exposures

Immunosuppression due to therapy; systemic anticancer therapy (IO or non-IO).

Main Outcomes and Measures

The primary outcome was a 5-level ordinal scale of COVID-19 severity: no complications; hospitalized without requiring oxygen; hospitalized and required oxygen; intensive care unit admission and/or mechanical ventilation; death. The secondary outcome was the occurrence of cytokine storm.

Results

The median age of the entire cohort was 65 years (interquartile range [IQR], 54-74) years and 6359 patients were female (52.8%) and 6598 (54.8%) were non-Hispanic White. A total of 599 (5.0%) patients received IO, whereas 4327 (35.9%) received non-IO systemic anticancer therapies, and 7120 (59.1%) did not receive any antineoplastic regimen within 3 months prior to COVID-19 diagnosis. Although no difference in COVID-19 severity and cytokine storm was found in the IO group compared with the untreated group in the total cohort (adjusted odds ratio [aOR], 0.80; 95% CI, 0.56-1.13, and aOR, 0.89; 95% CI, 0.41-1.93, respectively), patients with baseline immunosuppression treated with IO (vs untreated) had worse COVID-19 severity and cytokine storm (aOR, 3.33; 95% CI, 1.38-8.01, and aOR, 4.41; 95% CI, 1.71-11.38, respectively). Patients with immunosuppression receiving non-IO therapies (vs untreated) also had worse COVID-19 severity (aOR, 1.79; 95% CI, 1.36-2.35) and cytokine storm (aOR, 2.32; 95% CI, 1.42-3.79).

Conclusions and Relevance

This cohort study found that in patients with cancer and COVID-19, administration of systemic anticancer therapies, especially IO, in the context of baseline immunosuppression was associated with severe clinical outcomes and the development of cytokine storm.

Trial Registration

ClinicalTrials.gov Identifier: NCT04354701.

A meta-analysis on the effects of incarceration-based opioid substitution treatment

Objective: Opioid substitution treatment (OST) is a common treatment for individuals who use opioids; however, empirical evidence on the effects of OST during incarceration is scarce. Our aim was to conduct a meta-analysis on the effects of incarceration-based OST on substance use, treatment engagement post-release and re-incarceration. Method: We searched for studies on individuals who were incarcerated and treated with OST, compared to a comparison group. Studies were only included if they reported data post-release. Results: N = 15 studies met the inclusion criteria. We found less opioid use, less other drug use, higher treatment engagement post-release and less re-incarceration among treated individuals compared to the comparison group. Moderator analyses showed some influence of length of follow-up period and study quality. Conclusions: Incarceration-based OST reduces drug use, re-incarceration and leads to higher treatment engagement after release. More research is needed on the effects of incarceration-based OST on secondary outcomes (e.g. health and social integration) and on factors that moderate these effects.

High throughput screen of small molecules as potential countermeasures to galactic cosmic radiation induced cellular dysfunction

Space travel increases galactic cosmic ray exposure to flight crews and this is significantly elevated once travel moves beyond low Earth orbit. This includes combinations of high energy protons and heavy ions such as ⁵⁶Fe or ¹⁶O. There are distinct differences in the biological response to low-energy transfer (x-rays) or high-energy transfer (High-LET). However, given the relatively low fluence rate of exposure during flight operations, it might be possible to manage these deleterious effects using small molecules currently available. Virtually all reports to date examining small molecule management of radiation exposure are based on low-LET challenges. To that end an FDA approved drug library (725 drugs) was used to perform a high throughput screen of cultured cells following exposure to galactic cosmic radiation. The H9c2 myoblasts, ES-D3 pluripotent cells, and Hy926 endothelial cell lines were exposed to a single exposure (75 cGy) using the 5-ion GCRsim protocol developed at the NASA Space Radiation Laboratory (NSRL). Following GCR exposure cells were maintained for up to two weeks. For each drug (@10µM), a hierarchical cumulative score was developed incorporating measures of mitochondrial and cellular function, oxidant stress and cell senescence. The top 160 scores were retested following a similar protocol using 1µM of each drug. Within the 160 drugs, 33 are considered to have an anti-inflammatory capacity, while others also indirectly suppressed pro-inflammatory pathways or had noted antioxidant capacity. Lead candidates came from different drug classes that included angiotensin converting enzyme inhibitors or AT1 antagonists, COX2 inhibitors, as well as drugs mediated by histamine receptors. Surprisingly, different classes of anti-diabetic medications were observed to be useful including sulfonylureas and metformin. Using a hierarchical decision structure, we have identified several lead candidates. That no one drug or even drug class was completely successful across all parameters tested suggests the complexity of managing the consequences of galactic cosmic radiation exposure.

Search for New Physics in Electronic Recoil Data from XENONnT

We report on a blinded analysis of low-energy electronic recoil data from the first science run of the XENONnT dark matter experiment. Novel subsystems and the increased 5.9 ton liquid xenon target reduced the background in the (1, 30) keV search region to (15.8±1.3)  events/(ton×year×keV), the lowest ever achieved in a dark matter detector and ∼5 times lower than in XENON1T. With an exposure of 1.16 ton-years, we observe no excess above background and set stringent new limits on solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter.

Material radiopurity control in the XENONnT experiment

The selection of low-radioactive construction materials is of the utmost importance for rare-event searches and thus critical to the XENONnT experiment. Results of an extensive radioassay program are reported, in which material samples have been screened with gamma-ray spectroscopy, mass spectrometry, and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{222}$$\end{document}222Rn emanation measurements. Furthermore, the cleanliness procedures applied to remove or mitigate surface contamination of detector materials are described. Screening results, used as inputs for a XENONnT Monte Carlo simulation, predict a reduction of materials background (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document}∼17%) with respect to its predecessor XENON1T. Through radon emanation measurements, the expected \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{222}$$\end{document}222Rn activity concentration in XENONnT is determined to be 4.2 (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{+0.5}_{-0.7}$$\end{document}-0.7+0.5) \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu $$\end{document}μBq/kg, a factor three lower with respect to XENON1T. This radon concentration will be further suppressed by means of the novel radon distillation system.

Probing local chromatin dynamics by tracking telomeres

Chromatin dynamics is key for cell viability and replication. In interphase, chromatin is decondensed, allowing the transcription machinery to access a plethora of DNA loci. Yet, decondensed chromatin occupies almost the entire nucleus, suggesting that DNA molecules can hardly move. Recent reports have even indicated that interphase chromatin behaves like a solid body on mesoscopic scales. To explore the local chromatin dynamics, we have performed single-particle tracking on telomeres under varying conditions. We find that mobile telomeres feature in all conditions a strongly subdiffusive, anti-persistent motion that is consistent with the monomer motion of a Rouse polymer in viscoelastic media. In addition, telomere trajectories show intermittent accumulations in local niches at physiological conditions, suggesting the surrounding chromatin to reorganize on these time scales. Reducing the temperature or exposing cells to osmotic stress resulted in a significant reduction of mobile telomeres and the number of visited niches. Altogether, our data indicate a vivid local chromatin dynamics, akin to a semi-dilute polymer solution, unless perturbations enforce a more rigid or entangled state of chromatin.

Conduction system pacing in paediatric patients: a single centre experience

Funding Acknowledgements

Type of funding sources: None.

Background

Paediatric patients with conduction abnormalities are generally exposed to life-long dyssynchronous pacing from a very early age. Thus, preservation of cardiac function during chronic ventricular pacing is important. Conduction system pacing (CSP) with His bundle pacing (HBP) or left bundle branch pacing (LBBP) is an alternative method to standard right ventricular (RV) pacing that may preserve physiological ventricular activation and avoid potential pacing-induced cardiomyopathy (1). However, data on feasibility and safety of various CSP approaches in paediatric patients with or without congenital heart disease (CHD) is scarce and mainly relies on case studies (2-4).

Purpose

To assess feasibility and outcomes of different CSP techniques in paediatric patients.

Methods

Consecutive paediatric patients in whom CSP was attempted in our centre between November 2019 and December 2021 were analysed. Acute implant success rate, complications, fluoroscopy times, and CSP pacing parameters during follow-up were assessed.

To reduce radiation exposure, minimal fluoroscopy technique with three-dimensional (3D) electro-anatomical mapping (EAM) was also used in some cases. Geometry of right atrium and RV, along with mapping of His signal for HBP and potential LBBP sites in the RV septum were created using a decapolar catheter from the right femoral vein. Once relevant anatomy was obtained, HBP or LBBP was attempted using commercially available CSP tools. The pacing lead tip was visualised using the 3D EAM system. Transient fluoroscopy was used only for perpendicular placement of the sheath to the RV septum during LBBP, sheath removal, lead loop assessment to allow linear growth, and atrial lead placement.

Results

Six patients (100% female, age 9.3 ± 3.9 years, weight 41.8 ± 22.9 kg, baseline QRS 111.5 ± 6.3ms, CHD 50%, previous device 33%) with congenital complete AV block received CSP. One patient received HBP and 5 LBBP. The procedure was acutely successful in all patients (100%), pacing thresholds were low (0.56 ± 0.18V at 0.5ms) and there were no perioperative complications. During mean follow-up of 11.8 ± 7.8 months pacing parameters remained stable. However, significant rise of the pacing threshold (&gt; 2.5V) was registered in the HBP patient, in whom lead revision was performed. Three-dimensional EAM was utilised in 3 patients (1 HBP, 2 LBBP). The use of minimal fluoroscopy technique with 3D EAM reduced fluoroscopy time (4.0, 3.2, 4.5 min vs. 9.5, 11.0, 8.0 min) without increasing procedural time (80, 70, 50 min vs. 110, 60, 75 min) compared to standard fluoroscopy technique.

Conclusion

Conduction system pacing is feasible and safe in paediatric patients with or without CHD. Additional utilisation of 3D EAM could reduce radiation exposure, without increasing procedural time. Future long-term studies should be considered to provide the ground for wider clinical adoption of CSP in paediatric population.

Examining allostatic load, neighborhood socioeconomic status, symptom burden and mortality in multiple myeloma patients

The objective of this study is to examine the association between neighborhood socioeconomic status (nSES) and baseline allostatic load (AL) and clinical trial endpoints in patients enrolled in the E1A11 therapeutic trial in multiple myeloma (MM). Study endpoints were symptom burden (pain, fatigue, and bother) at baseline and 5.5 months, non-completion of induction therapy, overall survival (OS) and progression-free survival (PFS). Multivariable logistic and Cox regression examined associations between nSES, AL and patient outcomes. A 1-unit increase in baseline AL was associated with greater odds of high fatigue at baseline (adjusted OR [95% CI] = 1.21 [1.08–1.36]) and a worse OS (adjusted hazard ratio, [95% CI] = 1.21 [1.06–1.37]). High nSES was associated with worse baseline bother (middle OR = 4.22 [1.11–16.09] and high 4.49 [1.16–17.43]) compared to low nSES. There was no association between AL or nSES and symptom burden at 5.5 months, non-completion of induction therapy or PFS. Additionally, there was no association between nSES and OS. AL may have utility as a predictive marker for OS among patients with MM and may allow individualization of treatment. Future studies should standardize and validate AL patients with MM.

Patients recently treated for B-lymphoid malignancies show increased risk of severe COVID-19: a CCC19 registry analysis

Patients with B-lymphoid malignancies have been consistently identified as a population at high risk of severe COVID-19. Whether this is exclusively due to cancer-related deficits in humoral and cellular immunity, or whether risk of severe COVID-19 is increased by anti-cancer therapy, is uncertain. Using data derived from the COVID-19 and Cancer Consortium (CCC19), we show that patients treated for B-lymphoid malignancies have an increased risk of severe COVID-19 compared to control populations of patients with non-B-lymphoid hematologic malignancies. Among patients with B-lymphoid malignancies, those who received anti-cancer therapy within 12 months of COVID-19 diagnosis experienced increased COVID-19 severity compared to patients with B-lymphoid malignancies off therapy, after adjustment for cancer status and several other prognostic factors. Our findings suggest that patients recently treated for a B-lymphoid malignancy are at uniquely high risk for severe COVID-19.

Outcomes on anti-VEGFR-2/paclitaxel treatment after progression on immune checkpoint inhibition in patients with metastatic gastroesophageal adenocarcinoma

Through our involvement in KEYNOTE-059, we unexpectedly observed durable responses in two patients with metastatic gastroesophageal adenocarcinoma (mGEA) who received ramucirumab (anti-VEGFR-2)/paclitaxel after immune checkpoint inhibition (ICI). To assess the reproducibility of this observation, we piloted an approach to administer ramucirumab/paclitaxel after ICI in more patients, and explored changes in the immune microenvironment. Nineteen consecutive patients with mGEA received ICI followed by ramucirumab/paclitaxel. Most (95%) did not respond to ICI, yet after irRECIST-defined progression on ICI, all patients experienced tumor size reduction on ramucirumab/paclitaxel. The objective response rate (ORR) and progression-free survival (PFS) on ramucirumab/paclitaxel after ICI were higher than on the last chemotherapy before ICI in the same group of patients (ORR, 58.8% vs 11.8%; PFS 12.2 vs 3.0 months; respectively). Paired tumor biopsies examined by imaging mass cytometry showed a median 5.5-fold (range 4-121) lower frequency of immunosuppressive forkhead box P3+ regulatory T cells with relatively preserved CD8+ T cells, post-treatment versus pre-treatment (n = 5 pairs). We then compared the outcomes of these 19 patients with a separate group who received ramucirumab/paclitaxel without preceding ICI (n = 68). Median overall survival on ramucirumab/paclitaxel was longer with (vs without) immediately preceding ICI (14.8 vs 7.4 months) including after multivariate analysis, as was PFS. In our small clinical series, outcomes appeared improved on anti-VEGFR-2/paclitaxel treatment when preceded by ICI, in association with alterations in the immune microenvironment. However, further investigation is needed to determine the generalizability of these data. Prospective clinical trials to evaluate sequential treatment with ICI followed by anti-VEGF(R)/taxane are underway.

Single-Particle Tracking Reveals Anti-Persistent Subdiffusion in Cell Extracts

Single-particle tracking (SPT) has become a powerful tool to quantify transport phenomena in complex media with unprecedented detail. Based on the reconstruction of individual trajectories, a wealth of informative measures become available for each particle, allowing for a detailed comparison with theoretical predictions. While SPT has been used frequently to explore diffusive transport in artificial fluids and inside living cells, intermediate systems, i.e., biochemically active cell extracts, have been studied only sparsely. Extracts derived from the eggs of the clawfrog Xenopus laevis, for example, are known for their ability to support and mimic vital processes of cells, emphasizing the need to explore also the transport phenomena of nano-sized particles in such extracts. Here, we have performed extensive SPT on beads with 20 nm radius in native and chemically treated Xenopus extracts. By analyzing a variety of distinct measures, we show that these beads feature an anti-persistent subdiffusion that is consistent with fractional Brownian motion. Chemical treatments did not grossly alter this finding, suggesting that the high degree of macromolecular crowding in Xenopus extracts equips the fluid with a viscoelastic modulus, hence enforcing particles to perform random walks with a significant anti-persistent memory kernel.

Association of clinical factors and recent anticancer therapy with COVID-19 severity among patients with cancer: a report from the COVID-19 and Cancer Consortium

BACKGROUND

Patients with cancer may be at high risk of adverse outcomes from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We analyzed a cohort of patients with cancer and coronavirus 2019 (COVID-19) reported to the COVID-19 and Cancer Consortium (CCC19) to identify prognostic clinical factors, including laboratory measurements and anticancer therapies.

PATIENTS AND METHODS

Patients with active or historical cancer and a laboratory-confirmed SARS-CoV-2 diagnosis recorded between 17 March and 18 November 2020 were included. The primary outcome was COVID-19 severity measured on an ordinal scale (uncomplicated, hospitalized, admitted to intensive care unit, mechanically ventilated, died within 30 days). Multivariable regression models included demographics, cancer status, anticancer therapy and timing, COVID-19-directed therapies, and laboratory measurements (among hospitalized patients).

RESULTS

A total of 4966 patients were included (median age 66 years, 51% female, 50% non-Hispanic white); 2872 (58%) were hospitalized and 695 (14%) died; 61% had cancer that was present, diagnosed, or treated within the year prior to COVID-19 diagnosis. Older age, male sex, obesity, cardiovascular and pulmonary comorbidities, renal disease, diabetes mellitus, non-Hispanic black race, Hispanic ethnicity, worse Eastern Cooperative Oncology Group performance status, recent cytotoxic chemotherapy, and hematologic malignancy were associated with higher COVID-19 severity. Among hospitalized patients, low or high absolute lymphocyte count; high absolute neutrophil count; low platelet count; abnormal creatinine; troponin; lactate dehydrogenase; and C-reactive protein were associated with higher COVID-19 severity. Patients diagnosed early in the COVID-19 pandemic (January-April 2020) had worse outcomes than those diagnosed later. Specific anticancer therapies (e.g. R-CHOP, platinum combined with etoposide, and DNA methyltransferase inhibitors) were associated with high 30-day all-cause mortality.

CONCLUSIONS

Clinical factors (e.g. older age, hematological malignancy, recent chemotherapy) and laboratory measurements were associated with poor outcomes among patients with cancer and COVID-19. Although further studies are needed, caution may be required in utilizing particular anticancer therapies.

CLINICAL TRIAL IDENTIFIER

NCT04354701.

ECOG-ACRIN EAA181: Effective quadruplet utilization after treatment evaluation (EQUATE)—a randomized phase 3 trial for newly diagnosed multiple myeloma (NDMM) not intended for early autologous transplantation

TPS8052

Background: The monoclonal antibody (MoAb) daratumumab (dara) has been approved for treatment of newly diagnosed Multiple Myeloma (NDMM) in combination with lenalidomide (len) and dexamethasone (DRd) in patients who are not eligible to undergo stem cell transplantation (SCT). Ongoing trials are examining the role of adding bortezomib (Btz) to DRd, but it remains unclear if all patients benefit from a quadruplet regimen. Availability of sensitive assays to detect measurable/minimal residual disease (MRD) in MM and emerging data demonstrating significant prognostic value for attaining MRD negativity, offers an unprecedented opportunity to develop individualized treatment approaches. An important question is to identify who benefits from adding a fourth drug to the MoAb-IMiD triplet, thus individualizing therapy based on depth of response. We hypothesize that prolonged intensive therapy with the addition of Btz for consolidation and maintenance after DRd induction therapy for NDMM will improve survival outcomes with a more pronounced effect when used in MRD positive patients. Methods: Patients with NDMM, R-ISS Stage I or II, who are not eligible to undergo SCT or those willing to defer SCT to first relapse and have not received more than 1 cycle of any NDMM therapy will be enrolled, provided they have measurable disease, adequate organ and marrow function, have received no more than once cycle of therapy for MM and significant peripheral neuropathy or chronic obstructive pulmonary disease. Importantly, a dominant clone should be identified by lymphotrack assay for future MRD monitoring. Once enrolled, induction therapy will be in 28 day cycles consisting of daraSC (1800 mg) weekly for 2 cycles, every other week for cycles 3-6 and then every 4 weeks for 9 cycles, along with len 25 mg days 1-21 of each cycle and dex 40 mg (20 mg for those > 75 years) weekly. At end of 9 cycles (induction), patients will undergo MRD testing by next generation sequencing and will be classified into MRD positive or negative subgroups. Using MRD as an integral biomarker, the trial employs a randomized biomarker-stratified design as proposed by Freidlin et al. to determine efficacy for each MRD subgroup. Patients will be stratified by MRD status and R-ISS stage and randomized to receive 9 cycles of consolidation with DRd, without (control arm) or with (experimental arm) Btz (1.3 mg/m2 weekly for 3 of 4 weeks), followed by DR maintenance until progression The primary endpoint is consolidation OS. Sample size considerations rest on estimates of MRD subgroup prevalence at the end of induction and operating characteristics establishing the treatment effect within the MRD positive subgroup as primary and MRD negative subgroup as key secondary. The total accrual goal is 1450 patients. Clinical trial information: NCT04566328.

Unscrambling exit site patterns on the endoplasmic reticulum as a quenched demixing process

The endoplasmic reticulum (ER) is a vital organelle in mammalian cells with a complex morphology. Consisting of sheet-like cisternae in the cell center, the peripheral ER forms a vast tubular network on which a dispersed pattern of a few hundred specialized domains (ER exit sites (ERESs)) is maintained. Molecular details of cargo sorting and vesicle formation at individual ERESs, fueling the early secretory pathway, have been studied in some detail. The emergence of spatially extended ERES patterns, however, has remained poorly understood. Here, we show that these patterns are determined by the underlying ER morphology, suggesting ERESs to emerge from a demixing process that is quenched by the ER network topology. In particular, we observed fewer but larger ERESs when transforming the ER network to more sheet-like morphologies. In contrast, little to no changes with respect to native ERES patterns were observed when fragmenting the ER, indicating that hampering the diffusion-mediated coarse graining of domains is key for native ERES patterns. Model simulations support the notion of effective diffusion barriers impeding the coarse graining and maturation of ERES patterns. We speculate that tuning a simple demixing mechanism by the ER topology allows for a robust but flexible adaption of ERES patterns, ensuring a properly working early secretory pathway in a variety of conditions.

222 Rn emanation measurements for the XENON1T experiment

The selection of low-radioactive construction materials is of utmost importance for the success of low-energy rare event search experiments. Besides radioactive contaminants in the bulk, the emanation of radioactive radon atoms from material surfaces attains increasing relevance in the effort to further reduce the background of such experiments. In this work, we present the 222 Rn emanation measurements performed for the XENON1T dark matter experiment. Together with the bulk impurity screening campaign, the results enabled us to select the radio-purest construction materials, targeting a 222 Rn activity concentration of 10 μ Bq / kg in 3.2 t of xenon. The knowledge of the distribution of the 222 Rn sources allowed us to selectively eliminate problematic components in the course of the experiment. The predictions from the emanation measurements were compared to data of the 222 Rn activity concentration in XENON1T. The final 222 Rn activity concentration of ( 4.5 ± 0.1 ) μ Bq / kg in the target of XENON1T is the lowest ever achieved in a xenon dark matter experiment.

Search for Coherent Elastic Scattering of Solar ^{8}B Neutrinos in the XENON1T Dark Matter Experiment

We report on a search for nuclear recoil signals from solar ^{8}B neutrinos elastically scattering off xenon nuclei in XENON1T data, lowering the energy threshold from 2.6 to 1.6  keV. We develop a variety of novel techniques to limit the resulting increase in backgrounds near the threshold. No significant ^{8}B neutrinolike excess is found in an exposure of 0.6  t×y. For the first time, we use the nondetection of solar neutrinos to constrain the light yield from 1-2 keV nuclear recoils in liquid xenon, as well as nonstandard neutrino-quark interactions. Finally, we improve upon world-leading constraints on dark matter-nucleus interactions for dark matter masses between 3 and 11  GeV c^{-2} by as much as an order of magnitude.

Quantifying active diffusion in an agitated fluid

Mixing of reactants in microdroplets predominantly relies on diffusional motion due to small Reynolds numbers and the resulting absence of turbulent flows. Enhancing diffusion in microdroplets by an auxiliary noise source is therefore a topical problem. Here we report on how the diffusional motion of tracer beads is enhanced upon agitating the surrounding aqueous fluid with miniaturized magnetic stir bars that are compatible with microdroplets and microfluidic devices. Using single-particle tracking, we demonstrate via a broad palette of measures that local stirring of the fluid at different frequencies leads to an enhanced but apparently normal and homogenous diffusion process, i.e. diffusional steps follow the anticipated Gaussian distribution and no ballistic motion is observed whereas diffusion coefficients are significantly increased. The signature of stirring is, however, visible in the power-spectral density and in the velocity autocorrelation function of trajectories. Our data therefore demonstrate that diffusive mixing can be locally enhanced with miniaturized stir bars while only moderately affecting the ambient noise properties. The latter may also facilitate the controlled addition of nonequilibrium noise to complex fluids in future applications.

Microtubule polyglutamylation is important for regulating cytoskeletal architecture and motility in Trypanosoma brucei

The shape of kinetoplastids, such as Trypanosoma brucei, is precisely defined during the stages of the life cycle and governed by a stable subpellicular microtubule cytoskeleton. During the cell cycle and transitions between life cycle stages, this stability has to transiently give way to a dynamic behaviour to enable cell division and morphological rearrangements. How these opposing requirements of the cytoskeleton are regulated is poorly understood. Two possible levels of regulation are activities of cytoskeleton-associated proteins and microtubule post-translational modifications (PTMs). Here, we investigate the functions of two putative tubulin polyglutamylases in T. brucei, TTLL6A and TTLL12B. Depletion of both proteins leads to a reduction in tubulin polyglutamylation in situ and is associated with disintegration of the posterior cell pole, loss of the microtubule plus-end-binding protein EB1 and alterations of microtubule dynamics. We also observe a reduced polyglutamylation of the flagellar axoneme. Quantitative motility analysis reveals that the PTM imbalance correlates with a transition from directional to diffusive cell movement. These data show that microtubule polyglutamylation has an important role in regulating cytoskeletal architecture and motility in the parasite T. bruceiThis article has an associated First Person interview with the first author of the paper.