bluuebunny/crossref_metadata_2025 huggingface dataset:
Strategies to Optimize ICU Liberation (A to F) Bundle Performance in Critically Ill Adults With Coronavirus Disease 2019
Authors: Devlin John W. , O’Neal Hollis R. , Thomas Christopher , Barnes Daly Mary Ann , Stollings Joanna L. , Janz David R. , Ely E. Wesley , Lin John C.
Published: June 2020

Objectives:

The severe acute respiratory syndrome coronavirus 2 pandemic has stretched ICU resources in an unprecedented fashion and outstripped personal protective equipment supplies. The combination of a novel disease, resource limitations, and risks to medical personnel health have created new barriers to implementing the ICU Liberation (“A” for Assessment, Prevention, and Manage pain; “B” for Both Spontaneous Awakening Trials and Spontaneous Breathing Trials; “C” for Choice of Analgesia and Sedation; “D” for Delirium Assess, Prevent, and Manage; “E” for Early Mobility and Exercise; and “F” for Family Engagement and Empowerment [ABCDEF]) Bundle, a proven ICU care approach that reduces delirium, shortens mechanical ventilation duration, prevents post-ICU syndrome, and reduces healthcare costs. This narrative review acknowledges barriers and offers strategies to optimize Bundle performance in coronavirus disease 2019 patients requiring mechanical ventilation.

Data Sources, Study Selection, and Data Extraction:

The most relevant literature, media reports, and author experiences were assessed for inclusion in this narrative review including PubMed, national newspapers, and critical care/pharmacology textbooks.

Data Synthesis:

Uncertainty regarding coronavirus disease 2019 clinical course, shifts in attitude, and changes in routine behavior have hindered Bundle use. A domino effect results from: 1) changes to critical care hierarchy, priorities, and ICU team composition; 2) significant personal protective equipment shortages cause; 3) reduced/restricted physical bedside presence favoring; 4) increased depth of sedation and use of neuromuscular blockade; 5) which exacerbate drug shortages; and 6) which require prolonged use of limited ventilator resources. Other identified barriers include manageable knowledge deficits among non-ICU clinicians unfamiliar with the Bundle or among PICU specialists deploying pediatric-based Bundle approaches who are unfamiliar with adult medicine. Both groups have been enlisted to augment the adult ICU work force to meet demand. Strategies were identified to facilitate Bundle performance to liberate patients from the ICU.

Conclusions:

We acknowledge current challenges that interfere with comprehensive management of critically ill patients during the coronavirus disease 2019 pandemic. Rapid response to new circumstances precisely requires established safety mechanisms and protocols like the ABCDEF Bundle to increase ICU and ventilator capacity and help survivors maximize recovery from coronavirus disease 2019 as early as possible.
Acute Limb Ischemia Due to Arterial Thrombosis Associated With Coronavirus Disease 2019
Authors: Warrior Krishnan , Chung Paul A. , Ahmed Nida , Soult Michael C. , Simpson Kevin P.
Published: June 2020

Objectives:

To describe a case of acute limb ischemia caused by arterial thrombosis due to coronavirus disease 2019.

Design:

Clinical observation of a patient.

Setting:

Academic medical center.

Patient:

A 59-year-old female with history of hypertension, hyperlipidemia, and prior smoking.

Intervention:

Clinical observation and data extraction from electronic medical records.

Measurements and Main Results:

We report a case of peripheral arterial thrombosis associated with coronavirus disease 2019, resulting in acute limb ischemia of the right lower extremity. This event was heralded by a sudden and significant elevation in d-dimer levels. At the time of surgery, a long, gelatinous clot was retrieved from the right popliteal artery. Perioperatively, she continued to have absent pedal Doppler signals and after multiple embolectomy attempts, required distal arterial cut down with removal of additional thrombi and resultant improvement of distal arterial flow.

Conclusions:

This case demonstrates the importance of regularly checking d-dimer levels and vigilant monitoring for arterial thrombotic events, as they can rapidly become catastrophic.
Gestational Age and Risk of Mortality in Term-Born Critically Ill Neonates Admitted to PICUs in Australia and New Zealand*
Authors: Namachivayam Siva P. , Carlin John B. , Millar Johnny , Alexander Janet , Edmunds Sarah , Ganeshalingham Anusha , Lew Jamie , Erickson Simon , Butt Warwick , Schlapbach Luregn J. , Ganu Subodh , Festa Marino , Egan Jonathan R. , Williams Gary , Young Janelle ,   on behalf of Australian and New Zealand Intensive Care Society Paediatric Study Group (ANZICS PSG) and Australian and New Zealand Paediatric Intensive Care Registry (ANZPICR)
Published: June 2020

Objectives:

Gestational age at birth is declining, probably because more deliveries are being induced. Gestational age is an important modifiable risk factor for neonatal mortality and morbidity. We aimed to investigate the association between gestational age and mortality in hospital for term-born neonates (≥ 37 wk’) admitted to PICUs in Australia and New Zealand.

Design:

Observational multicenter cohort study.

Setting:

PICUs in Australia and New Zealand.

Patients:

Term-born neonates (≥ 37 wk) admitted to PICUs.

Interventions:

None

Measurements and Main Results:

We studied 5,073 infants born with a gestational age greater than or equal to 37 weeks and were less than 28 days old when admitted to a PICU in Australia or New Zealand between 2007 and 2016. The association between gestational age and mortality was estimated using a multivariable logistic regression model, adjusting for age, sex, indigenous status, Pediatric Index of Mortality version 2, and site. The median gestational age was 39.1 weeks (interquartile range, 38.2–40 wk) and mortality in hospital was 6.6%. Risk of mortality declined log-linearly with gestational age. The adjusted analysis showed a 20% (95% CI, 11–28%) relative reduction in mortality for each extra week of gestation beyond 37 weeks. The effect of gestation was stronger among those who received extracorporeal life support: each extra week of gestation was associated with a 44% (95% CI, 25–57%) relative reduction in mortality. Longer gestation was also associated with reduced length of stay in hospital: each week increase in gestation, the average length of stay decreased by 4% (95% CI, 2–6%).

Conclusions:

Among neonates born at “term” who are admitted to a PICU, increasing gestational age at birth is associated with a substantial reduction in the risk of dying in hospital. The maturational influence on outcome was more strongly noted in the sickest neonates, such as those requiring extracorporeal life support. This information is important in view of the increasing proportion of planned births in both high- and low-/middle-income countries.
MONOZYGOTIC TWINS DISCORDANT FOR ASYMMETRIC PIGMENTED PARAVENOUS CHORIORETINAL ATROPHY
Authors: Fischer Naomi , Duignan Emma , Robson Anthony G. , Webster Andrew R. , Ba-Abbad Rola
Published: June 2020

Purpose:

To demonstrate phenotypic discordance between a monozygotic twin pair, one of whom exhibited pigmented paravenous chorioretinal atrophy (PPCRA).

Methods:

A patient and his identical twin brother, attending Moorfields Eye Hospital, were reviewed. Clinical assessment included visual acuity and color vision testing, fundus imaging including autofluorescence, spectral-domain optical coherence tomography, and static perimetry. In addition, the affected sibling underwent pattern and full-field electroretinography (PERG and ERG) according to ISCEV standards. Zygosity testing was performed using short tandem repeat analysis.

Results:

The 48-year-old proband was referred with abnormal visual fields and difficulty reading at near. Examination revealed 20/20 Snellen visual acuity bilaterally, normal color vision, and bilateral asymmetric outer retinal atrophy with intraretinal pigment migration along the course of the retinal veins, consistent with PPCRA. The visual field defects were contiguous with the blind spot and mirrored the retinal involvement in both eyes. Pattern ERG showed mild macular dysfunction and full-field ERG was within normal limits. Blood testing for common uveitic entities was noncontributory. The proband's twin brother's clinical assessment and retinal imaging showed no abnormality. Zygosity testing showed the twins to be identical for 24 short tandem repeat microsatellite markers, indicative of monozygosity.

Conclusion:

Some cases of PPCRA, without an obvious inflammatory etiology, do not have a clear Mendelian inheritance pattern and may represent an acquired disorder.
Barriers to Delivery of Enteral Nutrition in Pediatric Intensive Care: A World Survey
Authors: Tume Lyvonne N. , Eveleens Renate D. , Verbruggen Sascha C. A. T. , Harrison Georgia , Latour Jos M. , Valla Frédéric V. ,   on behalf of the ESPNIC Metabolism, Endocrine and Nutrition section
Published: June 2020

Objectives:

To explore the perceived barriers by pediatric intensive care healthcare professionals (nurses, dieticians, and physicians) in delivering enteral nutrition to critically ill children across the world.

Design:

Cross-sectional international online survey adapted for use in pediatric settings.

Setting:

PICUs across the world.

Subjects:

PICU nurses, physicians, and dietitians.

Interventions:

The 20-item adult intensive care “Barriers to delivery of enteral nutrition” survey was modified for pediatric settings, tested, and translated into 10 languages. The survey was distributed online to pediatric intensive care nurses, physicians, and dieticians via professional networks in March 2019 to June 2019. Professionals were asked to rate each item indicating the degree to which they perceived it hinders the provision of enteral nutrition in their PICUs with a 7-point Likert scale from 0 “not at all a barrier” to 6 “an extreme amount.”

Measurement and Main Results:

Nine-hundred twenty pediatric intensive care professionals responded from 57 countries; 477 of 920 nurses (52%), 407 of 920 physicians (44%), and 36 of 920 dieticians (4%). Sixty-two percent had more than 5 years PICU experience and 49% worked in general PICUs, with 35% working in combined cardiac and general PICUs. The top three perceived barriers across all professional groups were as follows: 1) enteral feeds being withheld in advance of procedures or operating department visits, 2) none or not enough dietitian coverage on weekends or evenings, and 3) not enough time dedicated to education and training on how to optimally feed patients.

Conclusions:

This is the largest survey that has explored perceived barriers to the delivery of enteral nutrition across the world by physicians, nurses, and dietitians. There were some similarities with adult intensive care barriers. In all professional groups, the perception of barriers reduced with years PICU experience. This survey highlights implications for PICU practice around more focused nutrition education for all PICU professional groups.
Longitudinal Trajectories of Caregiver Distress and Family Functioning After Community-Acquired Pediatric Septic Shock
Authors: Murphy Lexa K. , Palermo Tonya M. , Meert Kathleen L. , Reeder Ron , Dean J. Michael , Banks Russell , Berg Robert A. , Carcillo Joseph A. , Chima Ranjit , McGalliard Julie , Haaland Wren , Holubkov Richard , Mourani Peter M. , Pollack Murray M. , Sapru Anil , Sorenson Samuel , Varni James W. , Zimmerman Jerry
Published: June 2020

Objectives:

To identify trajectories and correlates of caregiver distress and family functioning in families of children who survived community-acquired septic shock. We hypothesized that: 1) a substantial subset of families would demonstrate trajectories of persistent elevated caregiver distress and impaired family functioning 12 months after hospitalization and 2) sociodemographic and clinical risk factors would be associated with trajectories of persistent distress and family dysfunction.

Design:

Prospective cohort.

Setting:

Fourteen PICUs in the United States.

Patients:

Caregivers of 260 children who survived community-acquired septic shock.

Interventions:

None.

Measurements and Main Results:

Caregivers completed ratings of distress on the Brief Symptom Inventory and of family functioning on the Family Assessment Device at baseline, 1, 3, 6, and 12 months after hospitalization. Results from group-based trajectory modeling indicated that 67% of the current sample was characterized by persistent low caregiver distress, 26% by persistent moderate to high distress that remained stable across 12 months (high-risk caregiver distress group), and 8% by initial high distress followed by gradual recovery. Forty percent of the sample was characterized by stable high family functioning, 15% by persistent high dysfunction across 12 months (high-risk family functioning group), 12% by gradually improving functioning, and 32% by deteriorating function over time. Independently of age, child race was associated with membership in the high-risk caregiver distress group (non-white/Hispanic; effect size, –0.12; p = 0.010). There were no significant sociodemographic or clinical correlates of the high-risk family functioning group in multivariable analyses.

Conclusions:

Although the majority of families whose children survived community-acquired septic shock were characterized by resilience, a subgroup demonstrated trajectories of persistently elevated distress and family dysfunction during the 12 months after hospitalization. Results suggest a need for family-based psychosocial screening after pediatric septic shock to identify and support at-risk families.
Effects of the Non-Neutralizing Humanized Monoclonal Anti-Adrenomedullin Antibody Adrecizumab on Hemodynamic and Renal Injury in a Porcine Two-Hit Model
Authors: Thiele Christoph , Simon Tim-Philipp , Szymanski Jeanine , Daniel Christoph , Golias Christos , Hartmann Oliver , Struck Joachim , Martin Lukas , Marx Gernot , Schuerholz Tobias
Published: June 2020

Adrenomedullin is a vasoactive peptide that improves endothelial barrier function in sepsis, but may also cause hypotension and organ failure. Treatment with a non-neutralizing monoclonal anti-adrenomedullin antibody showed improvement in murine sepsis models. We tested the effects of the humanized monoclonal anti-adrenomedullin antibody Adrecizumab in a porcine two-hit model of hemorrhagic and septic shock.

In this randomized, blinded study 12 German Landrace pigs were bled to half of baseline mean arterial pressure for 45 min. Sepsis was induced using an Escherichia coli clot placed into the abdominal cavity 6 h after hemorrhagic shock. Animals received either 2 mg/kg BW anti-adrenomedullin antibody or vehicle solution immediately after sepsis induction. After 4 h, resuscitation was initiated using balanced crystalloids and noradrenalin to maintain a central venous pressure of 8 to 12 mm Hg, a mean arterial pressure ≥ 65 mm Hg, and a ScvO2 ≥70% for another 8 h. Hemodynamic parameters, laboratory parameters, and kidney histology were assessed.

The amount of volume resuscitation was significantly lower and significantly less animals developed a septic shock in the antibody-treated group, compared with the vehicle group. Kidney histology showed significantly lower granulocytes in both cortex and medulla in antibody-treated animals, while the remaining four kidney measures (serum creatinine and urine output and cortical and medullary injury in histopathology) did not reach the significance levels. After induction of sepsis, plasma adrenomedullin increased immediately in both the groups, but increased quicker and more pronounced in the antibody group.

In this two-hit shock model, treatment with an anti-adrenomedullin antibody significantly increased plasma adrenomedullin levels, while significantly less animals developed septic shock and renal granulocyte extravasation was significantly reduced. Thus, therapy with Adrecizumab may provide benefit in sepsis, and clinical investigation of this drug candidate is warranted.
A Comparative Study of Target Reconstruction of Ultra-High-Resolution CT for Patients with Corona-Virus Disease 2019 (COVID-19)
Authors: Lv Shao-mao , Lin Yu , Kang Jiang-he , Duan Shao-yin , Zhang Wei-guo , Wang Jin-an
Published: June 2020

Background

The corona-virus disease 2019 (COVID-19) pandemic has caused a serious public health risk. Compared with conventional high-resolution CT (C-HRCT, matrix 512), ultra-high resolution CT (U-HRCT, matrix 1024) can increase the effective pixel per unit volume by about 4 times. Our study is to evaluate the value of target reconstruction of U-HRCT in the accurate diagnosis of COVID-19.

Methods

A total of 13 COVID-19 cases, 44 cases of other pneumonias, and 6 cases of ground-glass nodules were retrospectively analyzed. The data were categorized into groups A (C-HRCT) and B (U-HRCT), following which iDose4-3 and iDose4-5 were used for target reconstruction, respectively. CT value, noise, and signal-to-noise ratio (SNR) in different reconstructed images were measured. Two senior imaging doctors scored the image quality and the structure of the lesions on a 5-point scale. Chi-square test, variance analysis, and binarylogistic regression analysis were used for statistical analysis.

Results

U-HRCT image can reduce noise and improve SNR with an increase of the iterative reconstruction level. The SNR of U-HRCT image was lower than that of the C-HRCT image of the same iDose4level, and the noise of U-HRCT was higher than that of C-HRCT image; the difference was statistically significant (P< 0.05). Logistic regression analysis showed thatperipleural distribution, thickening of blood vessels and interlobular septum, and crazy-paving pattern were independent indictors of the COVID-19 on U-HRCT. U-HRCT was superior to C-HRCT in showing the blood vessels, bronchial wall, and interlobular septum in the ground-glass opacities; the difference was statistically significant (P < 0.05).

Conclusions

Peripleural distribution, thickening of blood vessels and interlobular septum, and crazy-paving pattern on U-HRCT are favorable signs for COVID-19. U-HRCT is superior to C-HRCT in displaying the blood vessels, bronchial walls, and interlobular septum for evaluating COVID-19.
Burnout in radiation therapists in Portugal
Authors: Guerra Jéssica , Caramelo Francisco , Patrício Miguel
Published: June 2020

Background

Burnout syndrome has adverse consequences for individuals, causing a variety of cognitive, affective, physical, behavioural and motivational problems. We aim to assess burnout in Portuguese radiation therapists, for who high levels of contact with patients may potentially lead to burnout.

Methods

Radiation therapists working in Portugal were invited via e-mail to participate in the study by filling in a survey. The latter had two components: a social-demographic questionnaire and the Maslach Burnout Inventory – Human Services Survey.

Results

A total of 103 people responded to the survey, 95 of which employed as radiation therapists. The mean burnout scores were 20.60 ± 11.21, 7.43 ± 5.34 and 35.02 ± 6.02, for the emotional exhaustion, depersonalisation and personal accomplishment subscales, respectively. In the same order, the total of radiation therapists presenting high levels of burnout were 29%, 14.9% and 29.3% for the different dimensions. The mean scores of burnout did not differ significantly regarding gender, civil status, working in the public or private sector and years of service. Radiation therapists aged 40 years or older presented greater scores of burnout, though with no statistical significance.

Conclusion

Radiation therapists working in Portugal were seen to have average scores of burnout in the emotional exhaustion, depersonalisation and personal accomplishment subscales.
Structural characterization of the essential cell division protein FtsE and its interaction with FtsX inStreptococcus pneumoniae
Authors: Alcorlo Martin , Straume Daniel , Lutkenhaus Joe , Håvarstein Leiv Sigve , Hermoso Juan A.
Published: June 2020

FtsEX is a membrane complex widely conserved across diverse bacterial genera and involved in critical processes such as recruitment of division proteins and in spatial and temporal regulation of muralytic activity during cell division or sporulation. FtsEX is a member of the ABC transporter superfamily, where FtsX is an integral membrane protein and FtsE is an ATPase, required for mechanotransmission of the signal from the cytosol through the membrane, to regulate the activity of cell-wall hydrolases in the periplasm. Both proteins are essential in the major human respiratory pathogenic bacterium,Streptococcus pneumoniaeand interact with the modular peptidoglycan hydrolase PcsB at the septum. Here, we report the high-resolution structures of pneumococcal FtsE in complex with different nucleotides. Structural analysis reveals that FtsE contains all the conserved structural motifs associated with ATPase activity, and allowed interpretation of thein vivodimeric arrangement in both ADP and ATP states. Interestingly, three specific FtsE regions were identified with high structural plasticity that shape the cavity in which the cytosolic region of FtsX would be inserted. The residues corresponding to the FtsX coupling helix, responsible for FtsE contact, were identified and validated byin vivomutagenesis studies showing that this interaction is essential for cell growth and proper morphology.

IMPORTANCE

Bacterial cell division is a central process that requires exquisite orchestration of both the cell wall biosynthetic and lytic machineries. The essential membrane complex FtsEX, widely conserved across bacteria, play a central role by recruiting proteins to the divisome apparatus and by regulating periplasmic muralytic activity from the cytosol. FtsEX is a member of the Type VII family of the ABC-superfamily but instead transporter, couple ATP hydrolysis by FtsE to mechanically transduce a conformational signal to activate PG hydrolases. So far, no structural information is available for FtsE. Here we provide the structural characterization of FtsE confirming its ATPase nature and revealing regions with high structural plasticity key for FtsX binding. The complementary region in FtsX has been also identified and validatedin vivo. Our results provide evidences on how difference between ATP and ADP states in FtsE would dramatically alter FtsEX interaction with PG hydrolase PcsB in pneumococcal division.
First Clinical Use of Lenzilumab to Neutralize GM-CSF in Patients with Severe and Critical COVID-19 Pneumonia
Authors: Temesgen Zelalem , Assi Mariam , Vergidis Paschalis , Rizza Stacey A. , Bauer Philippe R. , Pickering Brian W. , Razonable Raymund R. , Libertin Claudia R. , Burger Charles D. , Orenstein Robert , Vargas Hugo E. , Varatharaj Palraj Bharath Raj , Dababneh Ala S. , Chappell Gabrielle , Chappell Dale , Ahmed Omar , Sakemura Reona , Durrant Cameron , Kenderian Saad S. , Badley Andrew D.
Published: June 2020

Background

In COVID-19, high levels of granulocyte macrophage-colony stimulating factor (GM-CSF) and inflammatory myeloid cells correlate with disease severity, cytokine storm, and respiratory failure. With this rationale, we used lenzilumab, an anti-human GM-CSF monoclonal antibody, to treat patients with severe and critical COVID-19 pneumonia.

Methods

Hospitalized patients with COVID-19 pneumonia and risk factors for poor outcomes were treated with lenzilumab 600 mg intravenously for three doses through an emergency single-use IND application. Patient characteristics, clinical and laboratory outcomes, and adverse events were recorded. All patients receiving lenzilumab through May 1, 2020 were included in this report.

Results

Twelve patients were treated with lenzilumab. Clinical improvement was observed in 11 out of 12 (92%), with a median time to discharge of 5 days. There was a significant improvement in oxygenation: The proportion of patients with SpO2/FiO2 < 315 at the end of observation was 8% vs. compared to 67% at baseline (p=0.00015). A significant improvement in mean CRP and IL-6 values on day 3 following lenzilumab administration was also observed (137.3 mg/L vs 51.2 mg/L, p = 0.040; 26.8 pg/mL vs 16.1 pg/mL, p = 0.035; respectively). Cytokine analysis showed a reduction in inflammatory myeloid cells two days after lenzilumab treatment. There were no treatment-emergent adverse events attributable to lenzilumab, and no mortality in this cohort of patients with severe and critical COVID-19 pneumonia.

Conclusions

In high-risk COVID-19 patients with severe and critical pneumonia, GM-CSF neutralization with lenzilumab was safe and associated with improved clinical outcomes, oxygen requirement, and cytokine storm.
Covid-19 vs BCG: Statistical Significance Analysis
Authors: Dolgikh Serge
Published: June 2020

We present an updated time-adjusted dataset and conclusions at Covid-19 Time Zero + 5 month (04.06.2020). The conclusions of the original analysis reviewed and mostly maintained at this time point. With the data accumulated to date a statistical significance of the BCG immunization correlation hypothesis is evaluated with the conclusion that it has achieved the level of confidence. Several specific cases are discussed with respect to the induced immunity hypothesis.
Tip60 protects against amyloid-β peptide-induced transcriptomic alterations via different modes of action in early versus late stages of neurodegenerative progression
Authors: Zhang Haolin , Karisetty Bhanu Chandra , Bhatnagar Akanksha , Armour Ellen M. , Beaver Mariah , Roach Tiffany V. , Mortazavi Sina , Mandloi Shreya , Elefant Felice
Published: June 2020

Alzheimer’s disease (AD) is an age-related neurodegenerative disorder hallmarked by amyloid-β (Aβ) plaque accumulation, neuronal cell death, and cognitive deficits that worsen during disease progression. Histone acetylation dysregulation, caused by an imbalance between reduced histone acetyltransferases (HAT) Tip60 and increased histone deacetylase 2 (HDAC2) levels, can directly contribute to AD pathology. However, whether such AD-associated neuroepigenetic alterations occur in response to Aβ peptide production and can be protected against by increasing Tip60 levels over the course of neurodegenerative progression remains unknown. Here we profile Tip60 HAT/HDAC2 dynamics and transcriptome-wide changes across early and late stage AD pathology in theDrosophilabrain produced solely by human amyloid-β42. We show that early Aβ42induction leads to disruption of Tip60 HAT/HDAC2 balance during early neurodegenerative stages preceding Aβ plaque accumulation that persists into late AD stages. Correlative transcriptome-wide studies reveal alterations in biological processes we classified as transient (early-stage only), late-onset (late-stage only), and constant (both). Increasing Tip60 HAT levels in the Aβ42fly brain protects against AD functional pathologies that include Aβ plaque accumulation, neural cell death, cognitive deficits, and shorter life-span. Strikingly, Tip60 protects against Aβ42-induced transcriptomic alterationsviadistinct mechanisms during early and late stages of neurodegeneration. Our findings reveal distinct modes of neuroepigenetic gene changes and Tip60 neuroprotection in early versus late stages in AD that can serve as early biomarkers for AD, and support the therapeutic potential of Tip60 over the course of AD progression.
Single cell transfection of human induced pluripotent stem cells using a droplet-based microfluidic system
Authors: Pérez C. , Sanluis-Verdes A. , Waisman A. , Lombardi A. , Rosero G. , La Greca A. , Bhansali S. , Bourguignon N. , Luzzani C. , Pérez M.S. , Miriuka S. , Lerner B.
Published: June 2020

Microfluidic tools have recently made possible many advances in biological and biomedical research. Research fields such as Physics, Engineering, Chemistry and Biology have combined to produce innovation in Microfluidics which has positively impacted on areas as diverse as nucleotide sequence, functional genomics, single-cell studies, single molecules assays, and biomedical diagnostics. Among these areas regenerative medicine and stem cells have benefited from Microfluidics due to these tools have had a profound impact on their applications. In the study, we present a high-performance droplet-based system for transfecting individual human-induced pluripotent stem cells. We show that this system has great efficiency in single cells and captured droplets, similar to other microfluidic methods and lower cost. We demonstrate that this microfluidic approach can be associated with the PiggyBac transposase-based system to increase its transfection efficiency. Our results provide a starting point for subsequent applications in more complex transfection systems, single-cell differentiation interactions, cell subpopulations, cell therapy, among other potential applications.
Toxoplasma gondiiAP2XII-2 contributes to proper progression through S-phase of the cell cycle
Authors: Srivastava Sandeep , White Michael W. , Sullivan William J.
Published: June 2020

Toxoplasma gondiiis a protozoan parasite that causes lifelong chronic infection that can reactivate in immunocompromised individuals. Upon infection, the replicative stage (tachyzoite) converts into a latent tissue cyst stage (bradyzoite). Like other apicomplexans,T. gondiipossesses an extensive linage of proteins called ApiAP2s that contain plant-like DNA-binding domains. The function of most ApiAP2s is unknown. We previously found that AP2IX-4 is a cell cycle-regulated ApiAP2 expressed only in dividing parasites as a putative transcriptional repressor. In this study, we purified proteins interacting with AP2IX-4, finding it to be a component of the recently characterized microrchidia (MORC) transcriptional repressor complex. We further analyzed AP2XII-2, another cell cycle-regulated factor that associates with AP2IX-4. We monitored parallel expression of AP2IX-4 and AP2XII-2 proteins in tachyzoites, detecting peak expression during S/M phase. Unlike AP2IX-4, which is dispensable in tachyzoites, loss of AP2XII-2 resulted in a slowed tachyzoite growth due to a delay in S-phase progression. We also found that AP2XII-2 depletion increased the frequency of bradyzoite differentiation in vitro. These results suggest that multiple AP2 factors collaborate to ensure proper cell cycle progression and tissue cyst formation inT. gondii.

Importance

Toxoplasma gondiiis a single-celled parasite that causes opportunistic infection due to its ability to convert into a latent cyst stage. This work describes a new transcriptional factor called AP2XII-2 that plays a role in properly maintaining the growth rate of replicating parasites, which contributes to signals required for development into its dormant stage. Without AP2XII-2,Toxoplasmaparasites experience a delay in their cell cycle that increases the frequency of latent cyst formation. In addition, we found that AP2XII-2 operates in a multi-subunit complex with other AP2 factors and chromatin remodeling machinery that represses gene expression. These findings add to our understanding of howToxoplasmaparasites balance replication and dormancy, revealing novel points of potential therapeutic intervention to disrupt this clinically relevant process.
Retarded Logistic Equation as a Universal Dynamic Model for the Spread of COVID-19
Authors: Shayak B , Sharma Mohit M
Published: June 2020

In this work we propose the retarded logistic equation as a dynamic model for the spread of COVID-19 all over the world. This equation accounts for asymptomatic transmission, pre-symptomatic or latent transmission as well as contact tracing and isolation, and leads to a transparent definition of the instantaneous reproduction number R. For different parameter values, the model equation admits different classes of solutions. These solution classes correspond to, inter alia, containment of the outbreak via public health measures, exponential growth despite public health measures, containment despite reopening and second wave following reopening. We believe that the spread of COVID in every localized area such as a city, district or county can be accounted for by one of our solution classes. In regions where R > 1 initially despite aggressive epidemic management efforts, we find that if the mitigation measures are sustained, then it is still possible for R to dip below unity when far less than the region’s entire population is affected, and from that point onwards the outbreak can be driven to extinction in time. We call this phenomenon partial herd immunity. Our analysis indicates that COVID-19 is an extremely vicious and unpredictable disease which poses unique challenges for public health authorities, on account of which “case races” among various countries and states do not serve any purpose and present delusive appearances while ignoring significant determinants.
Beyond forest succession: a gap model to study ecosystem functioning and tree community composition under climate change
Authors: Morin Xavier , de Coligny François , Martin-StPaul Nicolas , Bugmann Harald , Cailleret Maxime , Limousin Jean-Marc , Ourcival Jean-Marc , Prevosto Bernard , Simioni Guillaume , Vennetier Michel , Guillemot Joannès
Published: June 2020

Climate change impacts forest functioning and dynamics, and large uncertainties remain regarding the interactions between species composition, demographic processes, and environmental drivers. There are few robust tools available to link these processes, which precludes accurate projections and recommendations for long-term forest management. Forest gap-models present a balance between complexity and generality and are widely used in predictive forest ecology. However, their relevance to tackle questions about the links between species composition, climate and forest functioning is unclear. In this regard, demonstrating the ability of gap-models to predict the growth of forest stands at the annual time scale – representing a sensitive and integrated signal of tree functioning and mortality risk - appears as a fundamental step.

In this study, we aimed at assessing the ability of a gap-model to accurately predict forest growth in the short-term and potential community composition in the long-term, across a wide range of species and environmental conditions. To do so, we present the gap-model ForCEEPS, calibrated using an original parameterization procedure for the main tree species in France. ForCEEPS was shown to satisfactorily predict forest annual growth (averaged over a few years) at the plot level from mountain to Mediterranean climates, regardless the species. Such an accuracy was not gained at the cost of losing precision for long-term predictions, as the model showed a strong ability to predict potential community composition along a gradient of sites with contrasted conditions. The mechanistic relevance of ForCEEPS parameterization was explored by showing the congruence between the values of key model parameter and species functional traits. We further showed that accounting for the spatial configuration of crowns within forest stands, the effects of climatic constraints and the variability of shade tolerances in the species community are all crucial to better predict short-term productivity with gap-models.

The dual ability of predicting short-term functioning and long-term community composition, as well as the balance between generality and realism (i.e., predicting accuracy) of the new generation of gap-models may open great perspectives for the exploration of the biodiversity-ecosystem functioning relationships, species coexistence mechanisms, and the impacts of climate change on forest ecosystems.
Patch-clamp recordings in slices of telencephalon, diencephalon and rhombencephalon of salamanders
Authors: Flaive Aurélie , Ryczko Dimitri
Published: June 2020

Abstract

The salamander is a key limbed vertebrate from which many major scientific questions can be addressed in the fields of motor control, evolutionary biology, and regeneration biology. An important gap of knowledge is the description of the electrophysiological properties of the neurons constituting their central nervous system. To our knowledge, some patch-clamp electrophysiological recordings were done in the spinal cord and recently in hindbrain slices, but not in any higher brain region. Here, we present a method to obtain patch-clamp recordings in slices of the telencephalon, diencephalon and rhombencephalon of salamanders. The method includes dissection of the brain, brain slice preparation, visual identification of neurons and patch-clamp recordings. We provide single cell recordings in the rhombencephalon, diencephalon and telencephalon of salamanders. This method should open new avenues to dissect the operation of salamander brain circuits at the cellular level.

Highlights

- Salamander brain slices of telencephalon, diencephalon, and rhombencephalon

- Patch-clamp recordings in salamander brain slices

- The salamander as a model to decipher tetrapod neural microcircuits
Detection of uncoupled circadian rhythms in individual cells ofLemna minorusing a dual-color bioluminescence monitoring system
Authors: Watanabe Emiri , Isoda Minako , Muranaka Tomoaki , Ito Shogo , Oyama Tokitaka
Published: June 2020

The plant circadian oscillation system is based on the circadian clock of individual cells and coordinates the circadian behavior of the plant body. To observe the cellular circadian behavior of both the oscillator and its output in plants, we developed the dual-color bioluminescence monitoring system that automatically measured the luminescence of two luciferase reporters simultaneously at a single-cell level. We selected a yellow-green-emitting firefly luciferase (LUC+) and a red-emitting luciferase (PtRLUC) that is a mutant form of Brazilian click beetle ELUC. We usedAtCCA1::LUC+ andCaMV35S::PtRLUCto observe the cellular behavior of the oscillator and output, respectively. These bioluminescent reporters were introduced into the cells of a duckweed,Lemna minor, by particle bombardment. Time series of the bioluminescence of individual cells in a frond were obtained using a dual-color bioluminescence monitoring system with a green-pass- and red-pass filter. Luminescence intensities from the LUC+ and PtRLUC of each cell were calculated from the filtered luminescence intensities. We succeeded in reconstructing the bioluminescence behaviors ofAtCCA1::LUC+ andCaMV35S::PtRLUCin the same cells. Under prolonged constant light conditions,AtCCA1::LUC+ showed a robust circadian rhythm in individual cells in an asynchronous state in the frond, as previously reported in studies using other plants. In contrast,CaMV35S::PtRLUCstochastically showed circadian rhythms in a synchronous state. Thus, we clearly demonstrated the uncoupling between the oscillator and output in individual cells. This dual-color bioluminescence monitoring system is a powerful tool to analyze various stochastic phenomena accompanying large cell-to-cell variation in gene expression.

Significance statement

We succeeded in establishing the world’s first dual-color bioluminescence monitoring system at a single-cell level that enables simultaneous measurement of the luminescence activities of two reporter genes in plants. This system is a strong tool to analyze stochastic phenomena, and we clearly demonstrated the uncoupling of rhythmic behavior between two bioluminescent reporters in individual cells that stochastically occurred in the same plant.
Mutational inactivation of Apc in the intestinal epithelia compromises cellular organisation
Authors: Rannikmae Helena , Peel Samantha , Barry Simon , Sur Inderpreet , Taipale Jussi , Senda Takao , de la Roche Marc
Published: June 2020

The tumour suppressor adenomatous polyposis coli (Apc) regulates diverse effector pathways essential for cellular homeostasis. Truncating mutations in Apc, leading to the loss of its Wnt pathway and microtubule regulatory domains, are oncogenic in human and murine intestinal epithelia and drive malignant transformation. Whereas uncontrolled proliferation via Wnt pathway deregulation is an unequivocal consequence of oncogenic Apc mutations, it is not known whether loss of its other control systems contribute to tumorigenesis. Here we employin vitromodels of tumorigenesis to unmask the molecular barriers erected by Apc that maintain normal epithelial homeostasis in the murine intestinal epithelia. We determine that (i) enterocyte proliferation, (ii) microtubule dynamics and (iii) epithelial morphology are controlled by three independent molecular pathways, each corrupted by oncogenic Apc mutations. The key result of the study is to establish that Apc regulates three individual biological fates in the intestinal epithelia, through three distinct effector pathways, a significant advance to our understanding of normal tissue homeostasis, the molecular architecture of epithelial tissue and the aetiology of intestinal cancer.
Responsiveness variability during anaesthesia relates to inherent differences in brain structure and function of the fronto-parietal networks
Authors: Deng Feng , Taylor Nicola , Owen Adrian M. , Cusack Rhodri , Naci Lorina
Published: June 2020

Anaesthesia combined with functional neuroimaging provides a powerful approach for understanding the brain mechanisms of consciousness. Although propofol is used ubiquitously in clinical interventions that reversibly suppress consciousness, it shows large inter-individual variability, and the brain bases of this variability remain poorly understood. We asked whether three networks key to conscious cognition — the dorsal attention (DAN), executive control (ECN), and default mode (DMN) — underlie responsiveness variability under anaesthesia. Healthy participants (N=17) were moderately anaesthetized during narrative understanding and resting state conditions inside the Magnetic Resonance Imaging scanner. A target detection task measured behavioural responsiveness. An independent behavioural study (N=25) qualified the attention demands of narrative understanding. 30% of participants were unaffected in their response times, thus thwarting a key aim of anaesthesia — the suppression of behavioural responsiveness. Individuals with stronger functional connectivity within the DAN and ECN, between them, and to the DMN, and with larger grey matter volume in frontal regions were more resilient to anaesthesia. For the first time, we show that responsiveness variability during propofol anaesthesia relates to inherent differences in brain structure and function of the fronto-parietal networks, which can be predicted prior to sedation. Results highlight novel markers for improving awareness monitoring during clinical anaesthesia.

Key points

Moderate propofol anaesthesia showed highly variable effects across individuals

30% of healthy participants’ response times were unaffected by anaesthesia and 70% had significantly delayed, fragmented, or fully omitted responses

Grey matter volume in frontal cortex and functional connectivity of the fronto-parietal networks predicted resilience to anaesthesia
Nrf2 activator-encapsulating polymeric nanoparticles and LDL-like nanoparticles target atherosclerotic plaque
Authors: Maiocchi Sophie , Thai Sydney , Buglak Nicholas , Cartaya Ana , Anwar Arnida , Corbin Ian , Bahnson Edward
Published: June 2020

Atherosclerotic vascular disease is the leading cause of death world-wide with few novel therapies available in spite of the ongoing health burden. Oxidative stress is a well-established driver of atherosclerotic progression; however the clinical translation of redox-based therapies is lacking. One of the challenges facing redox-based therapies is their targeted delivery to cellular domains of redox dysregulation. In the current study we sought to develop NPs encapsulating redox-based interventions that exploit passive means of targeting to selectively accumulate in atherosclerotic plaque with the aim of enhancing the intra-plaque bioavailability of interventions. Herein we present two types of nanoparticles (NPs): (i) We have employed flash nanoprecipitation to synthesize polymeric NPs encapsulating the hydrophobic Nrf2 activator drug, CDDO-Methyl, (ii) we have generated LDL-like NPs encapsulating the anti-inflammatory compound, oleic acid (OA). Nrf2-activators are a promising class of redox-active drug molecules whereby activation of Nrf2 results in the expression of several antioxidant and cyto-protective enzymes. Moreover, local activation of Nrf2 within the atherosclerotic plaque can be athero-protective. In this study we characterize the physiochemical properties of these NPs as well as confirm in vitro association of NPs with murine macrophages. In vitro drug release of CDDO-Me from polymeric NPs was determined by Nrf2-ARE-driven GFP fluorescence. In vivo localization was assessed through immunofluorescence of histological sections as well as whole-tissue light sheet fluorescence microscopy. We show that CDDO-Me-NPs and LDL-OA-NPs selectively accumulate in atherosclerotic plaque of two widely-used murine models of atherosclerosis: ApoE-/-and LDLr-/-mice. Overall, these studies underline that targeting of atherosclerotic plaque is an effective means to enhance delivery of redox-based interventions. Future work will assess the therapeutic efficacy of intra-plaque Nrf2 activation or anti-inflammatory actions with CDDO-Me-NPs or LDL-OA-NPs, respectively.
Membrane-mediated forces can stabilize tubular assemblies of I-Bar proteins
Authors: Jarin Z. , Pak A. J. , Bassereau P. , Voth G. A.
Published: June 2020

Collective action by Inverse-BAR (I-BAR) domains drive micron-scale membrane remodeling. The macroscopic curvature sensing and generation behavior of I-BAR domains is well characterized, and computational models have suggested various mechanisms on simplified membrane systems, but there remain missing connections between the complex environment of the cell and the models proposed thus far. Here, we show a connection between the role of protein curvature and lipid clustering in the stabilization of large membrane deformations. We find lipid clustering provides a directional membrane-mediated interaction between membrane-bound I-BAR domains. Lipid clusters stabilize I-BAR domain aggregates that would not arise through membrane fluctuation-based or curvature-based interactions. Inside of membrane protrusions, lipid cluster-mediated interaction draws long side-by-side aggregates together resulting in more cylindrical protrusions as opposed to bulbous, irregularly shaped protrusions.

Statement of Significance

Membrane remodeling occurs throughout the cell and is crucial to proper cellular function. In the cellular environment, I-BAR proteins are responsible for sensing membrane curvature and initiating the formation of protrusions outward from the cell. Additionally, there is a large body of evidence that I-BAR domains are sufficient to reshape the membrane on scales much larger than any single domain. The mechanism by which I-BAR domains can remodel the membrane is uncertain. However, experiments show that membrane composition and most notably negatively-charge lipids like PIP2play a role in the onset of tubulation. Using coarse-grained models, we show that I-BAR domains can cluster negatively charge lipids and clustered PIP2-like membrane structures facilitate a directional membrane-mediated interaction between I-BAR domains.