Baseline Quality-of-Life of Caregivers of Patients With Heart Failure Prior to Advanced Therapies: Findings From the Sustaining Quality of Life of the Aged: Transplant or Mechanical Support (SUSTAIN-IT) Study

BACKGROUND

We compared health-related quality of life (HRQOL), depressive symptoms, anxiety, and burden in caregivers of older patients with heart failure based on the intended therapy goal of the patient: awaiting heart transplantation (HT) with or without mechanical circulatory support (MCS) or prior to long-term MCS; and we identified factors associated with HRQOL.

METHODS

Caregivers (n = 281) recruited from 13 HT and MCS programs in the United States completed measures of HRQOL (EQ-5D-3L), depressive symptoms (PHQ-8), anxiety (STAI-state), and burden (Oberst Caregiving Burden Scale). Analyses included ANOVA, Kruskal-Wallis tests, χ² tests, and linear regression.

RESULTS

The majority of caregivers were female, white spouses with ≤ 2 comorbidities, median [Q1,Q3] age = 62 [57.8, 67.0] years. Caregivers (HT with MCS = 87, HT without MCS = 98, long-term MCS = 96) reported similarly high baseline HRQOL (EQ-5D-3L visual analog scale median score = 90; P = 0.67 for all groups) and low levels of depressive symptoms. STAI-state median scores were higher in the long-term MCS group vs the HT groups with and without MCS, (38 vs 32 vs 31; P < 0.001), respectively. Burden (task: time spent/difficulty) differed significantly among groups. Caregiver factors (number of comorbidities, diabetes and higher anxiety levels) were significantly associated with worse caregiver HRQOL, R² = 26%.

CONCLUSIONS

Recognizing caregiver-specific factors, including comorbidities and anxiety, associated with the HRQOL of caregivers of these older patients with advanced HF may guide support strategies.

POS1268 PHASE II TRIAL OF ENPATORAN IN PATIENTS HOSPITALIZED WITH COVID-19 PNEUMONIA

Background

Enpatoran is a selective and potent dual toll-like receptor (TLR) 7/8 inhibitor in development for the treatment of cutaneous and systemic lupus erythematosus (CLE/SLE). Enpatoran inhibits TLR7/8 activation in vitro and suppresses disease activity in lupus mouse models.1 Enpatoran was well tolerated and had linear pharmacokinetic (PK) parameters in healthy volunteers.2 As TLR7/8 mediate immune responses to single-stranded RNA viruses, including SARS-CoV-2, it was postulated that enpatoran may prevent hyperinflammation and cytokine storm in COVID-19.

Objectives

In response to the COVID-19 pandemic, we conducted an exploratory Phase II trial to assess safety and determine whether enpatoran prevents clinical deterioration in patients (pts) hospitalized with COVID-19 pneumonia. PK and pharmacodynamics (PD) of enpatoran were also evaluated.

Methods

ANEMONE was a randomized, double-blind, placebo (PBO)-controlled study conducted in Brazil, the Philippines, and the USA (NCT04448756). Pts aged 18–75 years, hospitalized with COVID-19 pneumonia (WHO 9-point scale score =4) but not mechanically ventilated, with SpO2 <94% and PaO2/FiO2 ≥150 (FiO2 maximum 0.4) were eligible. Those with a history of uncontrolled illness, active/unstable cardiovascular disease and SARS-CoV-2 vaccination were excluded. Pts received PBO or enpatoran (50 or 100 mg twice daily [BID]) for 14 days, with monitoring to Day 28 and safety follow-up to Day 60. Primary outcomes were safety and time to recovery (WHO 9-point scale ≤3). Clinical deterioration (time to clinical status >4, WHO 9-point scale) was a secondary outcome. Exploratory endpoints were enpatoran and biomarker concentrations (cytokines, C-reactive protein [CRP], D-dimer and interferon gene signature [IFN-GS] scores) assessed over time.

Results

149 pts received either PBO (n=49), or enpatoran 50 mg (n=54) or 100 mg (n=46) BID; 88% completed treatment and 86% received concomitant steroids. Median age was 50 years (77% <60 years old), 66% were male, and 50% had ≥1 comorbidity (40% hypertension, 24% diabetes). Overall, 59% pts reported a treatment-emergent adverse event (TEAE) with three non-treatment-related deaths; 11% reported a treatment-related TEAE. The proportion of pts in the enpatoran group reporting serious TEAEs was low (50 mg BID 9%; 100 mg BID 2%) vs PBO (18%). Gastrointestinal disorders were most common (PBO 8%; 50 mg BID 28%; 100 mg BID 9%). The primary outcome of time to recovery with enpatoran vs PBO was not met; medians were 3.4–3.9 days. A positive signal in time to clinical deterioration from Day 1 through Day 28 was observed; hazard ratios [95% CI] for enpatoran vs PBO were 0.39 [0.13, 1.15] (50 mg BID) and 0.30 [0.08, 1.08] (100 mg BID). Mean enpatoran exposure was dose-proportional, and PK properties were within expectations. The median (quartile [Q]1– Q3) interleukin 6 (IL-6), CRP and D-dimer baseline concentration across the groups were 5.7 (4.0–13.5) pg/mL, 30.04 (11.40–98.02) and 0.62 (0.39–1.01) mg/L, respectively. Baseline IFN-GS scores were similar across groups.

Conclusion

The ANEMONE trial was the first to evaluate the safety and efficacy of a TLR7/8 inhibitor in an infectious disease for preventing cytokine storm. Enpatoran up to 100 mg BID for 14 days was well tolerated by patients acutely ill with COVID-19 pneumonia. Time to recovery was not improved with enpatoran, perhaps due to the younger age of patients who had fewer comorbidities compared to those in similar COVID-19 trials. However, there was less likelihood for clinical deterioration with enpatoran than placebo. This trial provides important safety, tolerability, PK and PD data supporting continued development of enpatoran in SLE and CLE (NCT04647708, NCT05162586).

References

[1]Vlach, et al. J Pharmacol Exp Ther 2021;376:397–409;

[2]Port, et al. Pharmacol Res Perspect 2021;9:e00842.

Acknowledgements

We would like to thank those who took part in the the ANEMONE trial. This study was sponsored by the healthcare business of Merck KGaA, Darmstadt, Germany (CrossRef Funder ID: 10.13039/100009945), who funded medical writing support by Bioscript Stirling Ltd.

Disclosure of Interests

John E. McKinnon Consultant of: EMD Serono Research & Development Institute, Inc., Billerica, MA, USA, an affiliate of Merck KGaA, Joel Santiaguel Speakers bureau: Merck Healthcare KGaA, Claudia Murta Speakers bureau: Pfizer/Wyeth, Dongzi Yu Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA), Mukhy Khursheed Employee of: Merck Serono Ltd (an affiliate of Merck KGaA), Flavie Moreau Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA), Lena Klopp-Schulze Employee of: Merck Healthcare KGaA, Jamie Shaw Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA), Sanjeev Roy Employee of: Ares Trading SA (an affiliate of Merck KGaA), Amy Kao Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA)

POS0189 EFFECT OF ATACICEPT ON RENAL FUNCTION IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS (SLE)

Background

Atacicept is a fusion protein that blocks B-lymphocyte stimulator and a proliferation-inducing ligand, which are increased in patients with SLE. APRIL-SLE was a double-blind, placebo-controlled, Phase 2 study that randomized patients with moderate-to-severe systemic lupus erythematosus (SLE) to atacicept 75 mg, atacicept 150 mg, or placebo twice-weekly for 4 weeks, then weekly for 48 weeks.

Objectives

The primary results of the APRIL-SLE study – the effect of atacicept compared to placebo in preventing new flares in patients with moderate-to-severe SLE – have been reported (Isenberg et al., 2013). We performed a post hoc analysis to describe the effect of atacicept compared to placebo on measures of renal function in patients with SLE; this effect has not been reported previously.

Methods

The APRIL-SLE study excluded patients with moderate to severe glomerulonephritis, as defined by either of the following: urinary protein/creatinine ratio (UPCR)>1 mg/mg and/or hematuria or a significant renal impairment as defined by estimated glomerular filtration rate (eGFR)<50 mL/min/1.73 m2. Patients with proteinuria and mild to moderate chronic kidney disease, as assessed by KDIGO criteria were eligible. UPCR and eGFR were measured at baseline, week 2, and then every 4 weeks until week 52. The median change from baseline to each of these timepoints was calculated for eGFR and UPCR using the Safety Analysis Set, comprised of all randomized patients who received at least 1 dose of study medication. Enrollment in the atacicept 150 mg group was discontinued prematurely due to 2 deaths from pneumonias. When treatment was discontinued, 62 of 144 patients in this group had completed 52 weeks of treatment; 27 other patients had already been withdrawn for various reasons; and, in the remaining 55 patients, treatment was stopped early as a safety precaution. Patients in the other two groups completed the protocol.

Results

In total, 111 patients in the placebo group, 112 patients in the atacicept 75 mg group, and 62 patients in the atacicept 150 mg group completed 52 weeks of treatment. The eGFR time course was stable for the atacicept groups compared to a 4.4% decline in the placebo group from baseline at week 52 (Figure 1 and Table 1). UPCR from baseline at week 52 declined in the atacicept groups and increased in the placebo group.

Table 1.

Median Percent Change from Baseline of Estimated Glomerular Filtration Rate (eGFR) and Proteinuria at Week 52 – Safety Analysis Set

VariablePlaceboAtacicept 75 mgAtacicept 150 mgeGFR (mL/min)n=110n=111n=62 bmedian-4.35-1.490.57UPCR (mg/mg)n=108n=108n=63median6.29-6.27-12.72UPCR (mg/mg) an=12n=15n=8median26.11-54.42-12.15

eGFR=estimated glomerular filtration rate; UPCR=urinary protein/creatinine ratio.

aAmong patients with screening UPCR ≥0.2 mg/mg.

bEnrollment in the atacicept 150 mg arm was discontinued prematurely (described in Isenberg et al., 2015).

Figure 1.

Median Change from Baseline in eGFR.

eGFR= estimated glomerular filtration rate; IQR=interquartile range

Conclusion

Results from this double-blind, placebo-controlled, Phase 2 study suggest a potential for improved renal function with atacicept treatment of patients with moderate-to-severe SLE.

References

[1]Isenberg D, Gordon C, Licu D, Copt S, Rossi CP, Wofsy D. Efficacy and safety of atacicept for prevention of flares in patients with moderate-to-severe systemic lupus erythematosus (SLE): 52-week data (APRIL-SLE randomised trial). Ann Rheum Dis. 2015;74(11):2006-15. Erratum in: Ann Rheum Dis. 2016 May;75(5):946.

Disclosure of Interests

David Isenberg Consultant of: Professor Isenberg has consulted for Veratx, Servier, Astro-Zeneca, Idorsia, Merck Serono, and Amgen. His honoraria are passed onto a local arthritis charity., Celia J. F. Lin Shareholder of: Dr. Lin is an employee of Vera Therapeutics, Inc., Employee of: Dr. Lin is an employee of Vera Therapeutics, Inc., Amy Kao Shareholder of: Dr. Kao own stocks of Merck KGaA, Darmstadt, Germany, Employee of: Dr. Kao is an employee of EMD Serono Research & Development Institute, Inc (a business of Merck KGaA), Aida Arselan Aydemir Employee of: Ms. Aydemir is an employee of EMD Serono Research & Development Institute, Inc (a business of Merck KGaA), Caroline Gordon Speakers bureau: Dr. Gordon reports personal fees for speakers bureau from UCB, Consultant of: Dr. Gordon reports personal fees for honoraria from consultancy work from the Center for Disease Control and Prevention, Amgen, Astra-Zeneca, AbbVie, EMD Serono, MGP, Sanofi, and UCB, Grant/research support from: Dr. Gordon reports an educational grant from UCB to Sandwell and West Birmingham Hospitals NHS Trust that supported previous research work unrelated to any specific drug (last payment July 2019).

Predicting concurrent structural mechanical mechanisms during microstructure evolution

The interdependence between structural mechanics and microstructure solidification has been widely observed experimentally as a factor leading to undesirable macroscopic properties and casting defects. Despite this, numerical modelling of microstructure solidification often neglects this interaction and is therefore unable to predict key mechanisms such as the development of misoriented grains. This paper presents a numerical method coupling a finite volume structural mechanics solver to a cellular automata solidification solver, where gravity or pressure-driven displacements alter the local orientation and thereby growth behaviour of the solidifying dendrites. Solutions obtained using this model are presented which show fundamental behaviours observed in experiments. The results show that small, localized deformations can lead to significant changes in the crystallographic orientation of a dendrite and ultimately affect the overall microstructure development. This article is part of the theme issue 'Transport phenomena in complex systems (part 2)'.

Dendritic growth of ice crystals: a test of theory with experiments

Motivated by an important application of dendritic crystals in the form of an elliptical paraboloid, which widely spread in nature (ice crystals), we develop here the selection theory of their stable growth mode. This theory enables us to separately define the tip velocity of dendrites and their tip diameter as functions of the melt undercooling. This, in turn, makes it possible to judge the microstructure of the material obtained as a result of the crystallization process. So, in the first instance, the steady-state analytical solution that describes the growth of such dendrites in undercooled one-component liquids is found. Then a system of equations consisting of the selection criterion and the undercooling balance that describes a stable growth mode of elliptical dendrites is formulated and analyzed. Three parametric solutions of this system are deduced in an explicit form. Our calculations based on these solutions demonstrate that the theoretical predictions are in good agreement with experimental data for ice dendrites growing at small undercoolings in pure water.

AB1338-HPR GLOBAL PATIENT PERSPECTIVE ON TOP CHALLENGES IN LUPUS CARE AND RESEARCH PARTICIPATION

Background:

The Addressing Lupus Pillars for Health Advancement (ALPHA) Project is a global consensus initiative to identify, prioritize and address top barriers in lupus drug development, clinical care and access to care. The Lupus Foundation of America convenes ALPHA with Tufts Center for the Study of Drug Development and a Global Advisory Committee of lupus experts representing clinician-scientists, industry and patients.

Objectives:

Collect global patient input to determine alignment with the lupus clinician-scientist community on prior published consensus of top lupus barriers.

Methods:

A 23-question online Qualtrics survey was developed to identify challenges across lupus diagnosis, clinical care and research participation. The survey, available in English, Spanish, Korean and simplified Chinese, was fielded in November 2019 to people with lupus and caregivers of children <18 with lupus. SPSS 26 and SAS 9.4 were used for descriptive statistics and sub-analysis.

Results:

Analysis included only consented responses with ≥ 68% survey completion (n=3,447) received across 83 countries. 95% were female with a mean age of 45. Respondents reported being White (57%), Black or of African descent (14%), Hispanic or Latino (18%) and Asian (10%). 65% resided in the US while 35% resided in countries outside of the US. 97% were people with lupus while 3% were caregivers to children <18 with lupus.

Highest ranked challenges were similar globally and across children and adults: medication side effects, lack of treatment options and high out-of-pocket costs. Managing side effects ranked significantly higher (p<.05) outside of the US (48%) compared to US (40%). 50% of caregivers reported managing side effects as the top challenge for children compared to 43% of adults (p<.05). Research participation was low (24%) and lower among children (16%). The top reason for not participating in a clinical trial was not being asked by their doctor.

Conclusion:

This global survey revealed that medication side effects and lack of effective treatments are top challenges for people with lupus, including children. Most respondents were never asked by their doctors to participate in a clinical trial, which may explain difficulties in trial recruitment. These barriers are consistent with prior published barriers identified by the clinician-scientist community.

Acknowledgments:

ALPHA sponsors: EMD Serono, GSK, Aurinia, Mallinckrodt

Disclosure of Interests:

Karin Tse: None declared, Yaritza Peña: None declared, Kathleen Arntsen: None declared, Sang-Cheol Bae: None declared, Lauren Bloch Consultant of: Faegre Drinker Consulting is a division of Faegre Drinker Biddle & Reath, a law and consulting firm that represents patient advocacy organizations and sponsors developing drugs, Ian N. Bruce Grant/research support from: Genzyme Sanofi, GSK, and UCB, Consultant of: Eli Lilly, AstraZeneca, UCB, Iltoo, and Merck Serono, Speakers bureau: UCB, Karen Costenbader Grant/research support from: Merck, Consultant of: Astra-Zeneca, Bradley Dickerson Employee of: Aurinia, Thomas Dörner Grant/research support from: Janssen, Novartis, Roche, UCB, Consultant of: Abbvie, Celgene, Eli Lilly, Roche, Janssen, EMD, Speakers bureau: Eli Lilly, Roche, Samsung, Janssen, Kenneth Getz: None declared, Amy Kao Employee of: EMD Serono, Susan Manzi: None declared, Eric F. Morand Grant/research support from: AstraZeneca, Consultant of: AstraZeneca, Speakers bureau: AstraZeneca, Sandra Raymond: None declared, Brad H Rovin Grant/research support from: GSK, Consultant of: GSK, Laura Schanberg Grant/research support from: Sobi, BMS, Consultant of: Aurinia, UCB, Sanofi, Victoria Werth Grant/research support from: Biogen, Celgene, Gilead, Janssen, Viela, Consultant of: Biogen, Gilead, Janssen, Abbvie, GSK, Resolve, AstraZeneca, Amgen, Eli Lilly, EMD Serono, BMS, Viela, Kyowa Kirin, Joan Von Feldt Shareholder of: GSK, Employee of: GSK, David Zook Consultant of: Faegre Drinker Consulting is a division of Faegre Drinker Biddle & Reath, a law and consulting firm that represents patient advocacy organizations and sponsors developing drugs, Leslie Hanrahan: None declared

Thermoelectric magnetohydrodynamic control of melt pool dynamics and microstructure evolution in additive manufacturing

Large thermal gradients in the melt pool from rapid heating followed by rapid cooling in metal additive manufacturing generate large thermoelectric currents. Applying an external magnetic field to the process introduces fluid flow through thermoelectric magnetohydrodynamics. Convective transport of heat and mass can then modify the melt pool dynamics and alter microstructural evolution. As a novel technique, this shows great promise in controlling the process to improve quality and mitigate defect formation. However, there is very little knowledge within the scientific community on the fundamental principles of this physical phenomenon to support practical implementation. To address this multi-physics problem that couples the key phenomena of melting/solidification, electromagnetism, hydrodynamics, heat and mass transport, the lattice Boltzmann method for fluid dynamics was combined with a purpose-built code addressing solidification modelling and electromagnetics. The theoretical study presented here investigates the hydrodynamic mechanisms introduced by the magnetic field. The resulting steady-state solutions of modified melt pool shapes and thermal fields are then used to predict the microstructure evolution using a cellular automata-based grain growth model. The results clearly demonstrate that the hydrodynamic mechanisms and, therefore, microstructure characteristics are strongly dependent on magnetic field orientation. This article is part of the theme issue 'Patterns in soft and biological matters'.

Modeling of dendrite growth from undercooled nickel melt: sharp interface model versus enthalpy method

The dendritic growth of pure materials in undercooled melts is critical to understanding the fundamentals of solidification. This work investigates two new insights, the first is an advanced definition for the two-dimensional stability criterion of dendritic growth and the second is the viability of the enthalpy method as a numerical model. In both cases, the aim is to accurately predict dendritic growth behavior over a wide range of undercooling. An adaptive cell size method is introduced into the enthalpy method to mitigate against 'narrow-band features' that can introduce significant error. By using this technique an excellent agreement is found between the enthalpy method and the analytic theory for solidification of pure nickel.

Thermal dependence of large-scale freckle defect formation

The fundamental mechanisms governing macroscopic freckle defect formation during directional solidification are studied experimentally in a Hele-Shaw cell for a low-melting point Ga-25 wt.% In alloy and modelled numerically in three dimensions using a microscopic parallelized Cellular Automata Lattice Boltzmann Method. The size and distribution of freckles (long solute channels, or chimneys) are shown to be strongly dependent on the thermal profile of the casting, with flat, concave and convex isotherms being considered. For the flat isotherm case, no large-scale freckles form, while for concave or convex isotherms, large freckles appear but in different locations. The freckle formation mechanism is as expected buoyancy-driven, but the chimney stability, its long-term endurance and its location are shown to depend critically on the detailed convective transport through the inter-dendritic region. Flow is generated by curved isopleths of solute concentration. As solute density is different from that of the bulk fluid, gravity causes 'uphill' or 'downhill' lateral flow from the sample centre to the edges through the mush, feeding the freckle. An excellent agreement is obtained between the numerical model and real-time X-ray observations of a solidifying sample under strictly controlled temperature conditions. This article is part of the theme issue 'Heterogeneous materials: metastable and non-ergodic internal structures'.

Perforated diverticulitis in the setting of ulcerative colitis: An unusual case report

INTRODUCTION

The association of diverticulitis with ulcerative colitis (UC) is rare and not well described. The sequelae of inflammatory bowel disease (IBD) such as perforation and fistula formation can mimic diverticular complications. Therefore, in an IBD patient, it can be difficult to distinguish the etiology of such complications and render definitive care.

PRESENTATION OF CASE

A 43-year-old man with a long history of UC presented with spontaneous sigmoid perforation and subsequent complications of colovesicular and colocutaneous fistulae requiring multiple procedural interventions. Ultimately, the etiology was confirmed as perforated diverticulitis superimposed on severe ulcerative colitis.

DISCUSSION

As perforated diverticulitis superimposed on UC is a rare entity in the current literature and there are many diagnostic difficulties that complicate this scenario. It is important to rule out other entities such as misdiagnosis of IBD or segmental colitis associated with diverticula (SCAD) that may have overlapping features.

CONCLUSION

Although diverticulitis in the setting of UC is an uncommon presentation, it remains important for medical practitioners to consider this scenario when encountering patients who may present in a similar fashion. As such, we put forth a process to aid in a diagnosis and management such that definitive care may not be delayed.

Thermoelectric magnetohydrodynamic effects on the crystal growth rate of undercooled Ni dendrites

In the undercooled solidification of pure metals, the dendrite tip velocity has been shown experimentally to have a strong dependence on the intensity of an external magnetic field, exhibiting several maxima and minima. In the experiments conducted in China, the undercooled solidification dynamics of pure Ni was studied using the glass fluxing method. Visual recordings of the progress of solidification are compared at different static fields up to 6 T. The introduction of microscopic convective transport through thermoelectric magnetohydrodynamics is a promising explanation for the observed changes of tip velocities. To address this problem, a purpose-built numerical code was used to solve the coupled equations representing the magnetohydrodynamic, thermal and solidification mechanisms. The underlying phenomena can be attributed to two competing flow fields, which were generated by orthogonal components of the magnetic field, parallel and transverse to the direction of growth. Their effects are either intensified or damped out with increasing magnetic field intensity, leading to the observed behaviour of the tip velocity. The results obtained reflect well the experimental findings.This article is part of the theme issue 'From atomistic interfaces to dendritic patterns'.

Improving diagnosis of acute appendicitis with atypical findings by Tc-99m HMPAO leukocyte scan

Aim: Even with careful observation, the overall false-positive rate of laparotomy remains 10-15% when acute appendicitis was suspected. Therefore, the clinical efficacy of Tc-99m HMPAO labeled leukocyte (TC-WBC) scan for the diagnosis of acute appendicitis in patients presenting with atypical clinical findings is assessed. Patients and Methods: Eighty patients presenting with acute abdominal pain and possible acute appendicitis but atypical findings were included in this study. After intravenous injection of TC-WBC, serial anterior abdominal/pelvic images at 30, 60, 120 and 240 min with 800k counts were obtained with a gamma camera. Any abnormal localization of radioactivity in the right lower quadrant of the abdomen, equal to or greater than bone marrow activity, was considered as a positive scan. Results: 36 out of 49 patients showing positive TC-WBC scans received appendectomy. They all proved to have positive pathological findings. Five positive TC-WBC were not related to acute appendicitis, because of other pathological lesions. Eight patients were not operated and clinical follow-up after one month revealed no acute abdominal condition. Three of 31 patients with negative TC-WBC scans received appendectomy. They also presented positive pathological findings. The remaining 28 patients did not receive operations and revealed no evidence of appendicitis after at least one month of follow-up. The overall sensitivity, specificity, accuracy, positive and negative predictive values for TC-WBC scan to diagnose acute appendicitis were 92, 78, 86, 82, and 90%, respectively. Conclusion: TC-WBC scan provides a rapid and highly accurate method for the diagnosis of acute appendicitis in patients with equivocal clinical examination. It proved useful in reducing the false-positive rate of laparotomy and shortens the time necessary for clinical observation.

Magnetic nanoparticles for ultrafast mechanical control of inner ear hair cells

We introduce cubic magnetic nanoparticles as an effective tool for precise and ultrafast control of mechanosensitive cells. The temporal resolution of our system is ∼1000 times faster than previously used magnetic switches and is comparable to the current state-of-the-art optogenetic tools. The use of a magnetism-gated switch reported here can address the key challenges of studying mechanotransduction in biological systems. The cube-shaped magnetic nanoparticles are designed to bind to components of cellular membranes and can be controlled with an electromagnet to exert pico-Newtons of mechanical force on the cells. The cubic nanoparticles can thus be used for noncontact mechanical control of the position of the stereocilia of an inner ear hair cell, yielding displacements of tens of nanometers, with sub-millisecond temporal resolution. We also prove that such mechanical stimulus leads to the influx of ions into the hair cell. Our study demonstrates that a magnetic switch can yield ultrafast temporal resolution, and has capabilities for remote manipulation and biological specificity, and that such magnetic system can be used for the study of mechanotransduction processes of a wide range of sensory systems.

Label-free direct visual analysis of hydrolytic enzyme activity using aqueous two-phase system droplet phase transitions

Dextran hydrolysis-mediated conversion of polyethylene glycol (PEG)-dextran (DEX) aqueous two-phase system droplets to a single phase was used to directly visualize Dextranase activity. DEX droplets were formed either by manual micropipetting or within a continuous PEG phase by computer controlled actuation of an orifice connecting rounded channels formed by backside diffused light lithography. The time required for the two-phase to one-phase transition was dependent on the Dextranase concentration, pH of the medium, and temperature. The apparent Michaelis constants for Dextranase were estimated based on previously reported catalytic constants, the binodal polymer concentration curves for PEG-DEX phase transition for each temperature, and pH condition. The combination of a microfluidic droplet system and phase transition observation provides a new method for label-free direct measurement of enzyme activity.

Delivery of proteases in aqueous two-phase systems enables direct purification of stem cell colonies from feeder cell co-cultures for differentiation into functional cardiomyocytes

Patterning of bioactive enzymes with subcellular resolution is achieved by dispensing droplets of dextran (DEX) onto polyethylene glycol (PEG)-covered cells though a glass capillary needle connected to a pneumatic pump. This technique is applied to purify colonies of induced pluripotent stem cells (iPSCs) from mouse embryonic fibroblast (MEF) feeder cultures and inefficiently induced iPSC colonies by selectively dissociating the iPSCs with proteases.

Low frequency entrainment of oscillatory bursts in hair cells

Sensitivity of mechanical detection by the inner ear is dependent upon a highly nonlinear response to the applied stimulus. Here we show that a system of differential equations that support a subcritical Hopf bifurcation, with a feedback mechanism that tunes an internal control parameter, captures a wide range of experimental results. The proposed model reproduces the regime in which spontaneous hair bundle oscillations are bistable, with sporadic transitions between the oscillatory and the quiescent state. Furthermore, it is shown, both experimentally and theoretically, that the application of a high-amplitude stimulus to the bistable system can temporarily render it quiescent before recovery of the limit cycle oscillations. Finally, we demonstrate that the application of low-amplitude stimuli can entrain bundle motility either by mode-locking to the spontaneous oscillation or by mode-locking the transition between the quiescent and oscillatory states.

Engineered yeast for enhanced CO2 mineralization

In this work, a biologically catalyzed CO₂ mineralization process for the capture of CO₂ from point sources was designed, constructed at a laboratory scale, and, using standard chemical process scale-up protocols, was modeled and evaluated at an industrial scale. A yeast display system in Saccharomyces cerevisae was used to screen several carbonic anhydrase isoforms and mineralization peptides for their impact on CO₂ hydration, CaCO₃ mineralization, and particle settling rate. Enhanced rates for each of these steps in the CaCO₃ mineralization process were confirmed using quantitative techniques in lab-scale measurements. The effect of these enhanced rates on the CO₂ capture cost in an industrial scale CO₂ mineralization process using coal fly ash as the CaO source was evaluated. The model predicts a process using bCA2- yeast and fly ash is ~10% more cost effective per ton of CO₂ captured than a process with no biological molecules, a savings not realized by wild-type yeast and high-temperature stable recombinant CA2 alone or in combination. The levelized cost of electricity for a power plant using this process was calculated and scenarios in which this process compares favorably to CO₂ capture by MEA absorption process are presented.