Dynamics of magnetization at infinite temperature in a Heisenberg spin chain

Understanding universal aspects of quantum dynamics is an unresolved problem in statistical mechanics. In particular, the spin dynamics of the one-dimensional Heisenberg model were conjectured as to belong to the Kardar-Parisi-Zhang (KPZ) universality class based on the scaling of the infinite-temperature spin-spin correlation function. In a chain of 46 superconducting qubits, we studied the probability distribution of the magnetization transferred across the chain's center, [Formula: see text]. The first two moments of [Formula: see text] show superdiffusive behavior, a hallmark of KPZ universality. However, the third and fourth moments ruled out the KPZ conjecture and allow for evaluating other theories. Our results highlight the importance of studying higher moments in determining dynamic universality classes and provide insights into universal behavior in quantum systems.

Myosin-5 varies its step length to carry cargo straight along the irregular F-actin track

Molecular motors employ chemical energy to generate unidirectional mechanical output against a track while navigating a chaotic cellular environment, potential disorder on the track, and against Brownian motion. Nevertheless, decades of nanometer-precise optical studies suggest that myosin-5a, one of the prototypical molecular motors, takes uniform steps spanning 13 subunits (36 nm) along its F-actin track. Here, we use high-resolution interferometric scattering microscopy to reveal that myosin takes strides spanning 22 to 34 actin subunits, despite walking straight along the helical actin filament. We show that cumulative angular disorder in F-actin accounts for the observed proportion of each stride length, akin to crossing a river on variably spaced stepping stones. Electron microscopy revealed the structure of the stepping molecule. Our results indicate that both motor and track are soft materials that can adapt to function in complex cellular conditions.

Stable quantum-correlated many-body states through engineered dissipation

Engineered dissipative reservoirs have the potential to steer many-body quantum systems toward correlated steady states useful for quantum simulation of high-temperature superconductivity or quantum magnetism. Using up to 49 superconducting qubits, we prepared low-energy states of the transverse-field Ising model through coupling to dissipative auxiliary qubits. In one dimension, we observed long-range quantum correlations and a ground-state fidelity of 0.86 for 18 qubits at the critical point. In two dimensions, we found mutual information that extends beyond nearest neighbors. Lastly, by coupling the system to auxiliaries emulating reservoirs with different chemical potentials, we explored transport in the quantum Heisenberg model. Our results establish engineered dissipation as a scalable alternative to unitary evolution for preparing entangled many-body states on noisy quantum processors.

Design and In Silico Evaluation of an Exercise Decision Support System Using Digital Twin Models

BACKGROUND

Managing glucose levels during exercise is challenging for individuals with type 1 diabetes (T1D) since multiple factors including activity type, duration, intensity and other factors must be considered. Current decision support tools lack personalized recommendations and fail to distinguish between aerobic and resistance exercise. We propose an exercise-aware decision support system (exDSS) that uses digital twins to deliver personalized recommendations to help people with T1D maintain safe glucose levels (70-180 mg/dL) and avoid low glucose (<70 mg/dL) during and after exercise.

METHODS

We evaluated exDSS using various exercise and meal scenarios recorded from a large, free-living study of aerobic and resistance exercise. The model inputs were heart rate, insulin, and meal data. Glucose responses were simulated during and after 30-minute exercise sessions (676 aerobic, 631 resistance) from 247 participants. Glucose outcomes were compared when participants followed exDSS recommendations, clinical guidelines, or did not modify behavior (no intervention).

RESULTS

exDSS significantly improved mean time in range for aerobic (80.2% to 92.3%, P < .0001) and resistance (72.3% to 87.3%, P < .0001) exercises compared with no intervention, and versus clinical guidelines (aerobic: 82.2%, P < .0001; resistance: 80.3%, P < .0001). exDSS reduced time spent in low glucose for both exercise types compared with no intervention (aerobic: 15.1% to 5.1%, P < .0001; resistance: 18.2% to 6.6%, P < .0001) and was comparable with following clinical guidelines (aerobic: 4.5%, resistance: 8.1%, P = N.S.).

CONCLUSIONS

The exDSS tool significantly improved glucose outcomes during and after exercise versus following clinical guidelines and no intervention providing motivation for clinical evaluation of the exDSS system.

Outcomes Following Treatment for Carotid Blowout in Head and Neck Cancer Patients

OBJECTIVE

The aim of the study was to determine outcomes after interventional radiology treatment of carotid blowout.

METHODS

Patients with head and neck cancer and who received interventional radiology treatment for carotid blowout between 2000 and 2022 were included. Pre-treatment, treatment, and post-treatment variables were evaluated.

RESULTS

Fourteen patients met inclusion criteria. Eleven patients (78.6%) had a history of radiation. Twelve (85.7%) blowouts occurred within 6 months of recent intervention. Initial treatment was with stenting (n = 9, 64.3%), coil embolization (n = 4, 28.6%), or both (n = 1, 7.1%). Six patients (42.9%) underwent subsequent carotid bypass. Morbidity following treatment included stroke (n = 1) and rebleeding (n = 4). Six-month survival was 57.1%. Of the patients who survived past six months, 5/8 were treated with carotid bypass and coverage. Four patients died of cancer progression, three of rebleeding, and three of medical complications.

CONCLUSION

The majority of carotid blowout occurs within 6 months of surgery or radiation. Many who survive will die of cancer progression or medical illness. Carotid bypass with flap coverage may be a worthwhile treatment for carotid blowout and should be considered as an adjunct to endovascular treatment.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:695-700, 2024.

Outcomes of Cranioplasty Reconstructions: Review of Cranioplasty Implants and Free Flap Coverage Variables that Affect Implant Exposure

BACKGROUND

Complex scalp wounds with cranial/dural involvement are challenging to reconstruct. Successful reconstruction can be achieved with cranial implants/hardware and free flap coverage. Wounds can breakdown and require revision procedures. We addressed reconstructive outcomes of different implants requiring free flaps.

OBJECTIVE

To determine the factors associated with implant exposure.

DESIGN

Multi-institutional retrospective review of 82 patients, 2000-2020, repaired with cranial implants and free flap coverage.

RESULTS

Implant exposure occurred in 13/82 (16%) reconstructions. Flap atrophy or thinning leading to implant exposure occurred in 11/82 (13%) reconstructions, including partial flap atrophy OR 0.05 (95% CI 0.0-0.35) and total flap atrophy OR 0.34 (95% CI 0.02-19.66). Revision surgeries that occurred subsequent to flap reconstruction were also associated with implant exposure (OR 0.02 (95% CI 0.0-0.19)). Implant exposure was not associated with radiation therapy, patient health history, implant type, flap type, or postoperative complications.

CONCLUSIONS

Implant exposure is associated with free flap atrophy, leading to inadequate implant coverage and the need for revision surgeries. Completing reconstruction with adequate soft tissue bulk and coverage and avoiding revision surgery may decrease the risk for implant exposure over time.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:2954-2958, 2023.

Measurement-induced entanglement and teleportation on a noisy quantum processor

Measurement has a special role in quantum theory1: by collapsing the wavefunction, it can enable phenomena such as teleportation2 and thereby alter the 'arrow of time' that constrains unitary evolution. When integrated in many-body dynamics, measurements can lead to emergent patterns of quantum information in space-time3-10 that go beyond the established paradigms for characterizing phases, either in or out of equilibrium11-13. For present-day noisy intermediate-scale quantum (NISQ) processors14, the experimental realization of such physics can be problematic because of hardware limitations and the stochastic nature of quantum measurement. Here we address these experimental challenges and study measurement-induced quantum information phases on up to 70 superconducting qubits. By leveraging the interchangeability of space and time, we use a duality mapping9,15-17 to avoid mid-circuit measurement and access different manifestations of the underlying phases, from entanglement scaling3,4 to measurement-induced teleportation18. We obtain finite-sized signatures of a phase transition with a decoding protocol that correlates the experimental measurement with classical simulation data. The phases display remarkably different sensitivity to noise, and we use this disparity to turn an inherent hardware limitation into a useful diagnostic. Our work demonstrates an approach to realizing measurement-induced physics at scales that are at the limits of current NISQ processors.

Myosin-5 varies its steps along the irregular F-actin track

Molecular motors employ chemical energy to generate unidirectional mechanical output against a track. By contrast to the majority of macroscopic machines, they need to navigate a chaotic cellular environment, potential disorder in the track and Brownian motion. Nevertheless, decades of nanometer-precise optical studies suggest that myosin-5a, one of the prototypical molecular motors, takes uniform steps spanning 13 subunits (36 nm) along its F-actin track. Here, we use high-resolution interferometric scattering (iSCAT) microscopy to reveal that myosin takes strides spanning 22 to 34 actin subunits, despite walking straight along the helical actin filament. We show that cumulative angular disorder in F-actin accounts for the observed proportion of each stride length, akin to crossing a river on variably-spaced stepping stones. Electron microscopy revealed the structure of the stepping molecule. Our results indicate that both motor and track are soft materials that can adapt to function in complex cellular conditions.

Non-Abelian braiding of graph vertices in a superconducting processor

Indistinguishability of particles is a fundamental principle of quantum mechanics¹. For all elementary and quasiparticles observed to date-including fermions, bosons and Abelian anyons-this principle guarantees that the braiding of identical particles leaves the system unchanged^2,3. However, in two spatial dimensions, an intriguing possibility exists: braiding of non-Abelian anyons causes rotations in a space of topologically degenerate wavefunctions^4-8. Hence, it can change the observables of the system without violating the principle of indistinguishability. Despite the well-developed mathematical description of non-Abelian anyons and numerous theoretical proposals^9-22, the experimental observation of their exchange statistics has remained elusive for decades. Controllable many-body quantum states generated on quantum processors offer another path for exploring these fundamental phenomena. Whereas efforts on conventional solid-state platforms typically involve Hamiltonian dynamics of quasiparticles, superconducting quantum processors allow for directly manipulating the many-body wavefunction by means of unitary gates. Building on predictions that stabilizer codes can host projective non-Abelian Ising anyons^9,10, we implement a generalized stabilizer code and unitary protocol²³ to create and braid them. This allows us to experimentally verify the fusion rules of the anyons and braid them to realize their statistics. We then study the prospect of using the anyons for quantum computation and use braiding to create an entangled state of anyons encoding three logical qubits. Our work provides new insights about non-Abelian braiding and, through the future inclusion of error correction to achieve topological protection, could open a path towards fault-tolerant quantum computing.

Success and Outcomes Following a Second Salvage Attempt for Free Flap Compromise in Patients Undergoing Head and Neck Reconstruction

Importance

Incidence of perioperative free flap compromise is low, with successful salvage in up to 70%. When the flap is compromised a second time, the value of intervening is unknown.

Objective

To assess the outcomes of a second revascularization attempt for compromised free flaps.

Design, Setting, and Participants

This multicenter retrospective medical record review included patients undergoing head and neck reconstruction with free flaps at 6 US medical centers from January 1, 2000, through December 30, 2020. Patients were 18 years or older with a history of head and neck defects from cancer, osteoradionecrosis, or other wounds. Of 3510 flaps identified, 79 were successfully salvaged once, became compromised a second time, and underwent attempted salvage.

Main Outcome and Measure

Flaps with a history of initial compromise and successful revascularization demonstrating second episodes of compromise followed by second salvage attempts.

Results

A total of 79 patients (mean age, 64 years; 61 [77%] men) were included in the analysis. Of the 79 flaps undergoing second salvage attempts, 24 (30%) survived while 55 (70%) demonstrated necrosis. Arterial or venous thrombectomy was performed in 17 of the 24 (71%) flaps that survived and 23 of the 55 (42%) flaps demonstrating necrosis (odds ratio, 3.38; 95% CI, 1.21-9.47). When venous compromise was encountered, changing the anastomotic vein was associated with decreased survival compared with not changing the vein (29 of 55 [53%] flaps vs 10 of 24 [42%] flaps); vein revision to an alternative branch was completed in 1 of the 24 (4%) flaps that survived and 19 of the 55 (35%) flaps with necrosis (odds ratio, 0.08; 95% CI, 0.00-0.60). Factors that were not associated with flap survival following second salvage attempts included flap type, cause of flap failure, postoperative complications, patient comorbidities, and heparin administration after second salvage.

Conclusions and Relevance

In this cohort study, second salvage was successful in 30% of free flaps. Flaps that underwent arterial or venous thrombectomy demonstrated better survival, while vein revision to neighboring branch veins was associated with worse flap outcomes.

Assembly principles of the human R2TP chaperone complex reveal the presence of R2T and R2P complexes

R2TP is a highly conserved chaperone complex formed by two AAA+ ATPases, RUVBL1 and RUVBL2, that associate with PIH1D1 and RPAP3 proteins. R2TP acts in promoting macromolecular complex formation. Here, we establish the principles of R2TP assembly. Three distinct RUVBL1/2-based complexes are identified: R2TP, RUVBL1/2-RPAP3 (R2T), and RUVBL1/2-PIH1D1 (R2P). Interestingly, we find that PIH1D1 does not bind to RUVBL1/RUVBL2 in R2TP and does not function as a nucleotide exchange factor; instead, RPAP3 is found to be the central subunit coordinating R2TP architecture and linking PIH1D1 and RUVBL1/2. We also report that RPAP3 contains an intrinsically disordered N-terminal domain mediating interactions with substrates whose sequences are primarily enriched for Armadillo repeat domains and other helical-type domains. Our work provides a clear and consistent model of R2TP complex structure and gives important insights into how a chaperone machine concerned with assembly of folded proteins into multisubunit complexes might work.

Micromirror Total Internal Reflection Microscopy for High-Performance Single Particle Tracking at Interfaces

Single particle tracking has found broad applications in the life and physical sciences, enabling the observation and characterization of nano- and microscopic motion. Fluorescence-based approaches are ideally suited for high-background environments, such as tracking lipids or proteins in or on cells, due to superior background rejection. Scattering-based detection is preferable when localization precision and imaging speed are paramount due to the in principle infinite photon budget. Here, we show that micromirror-based total internal reflection dark field microscopy enables background suppression previously only reported for interferometric scattering microscopy, resulting in nanometer localization precision at 6 μs exposure time for 20 nm gold nanoparticles with a 25 × 25 μm² field of view. We demonstrate the capabilities of our implementation by characterizing sub-nanometer deterministic flows of 20 nm gold nanoparticles at liquid-liquid interfaces. Our results approach the optimal combination of background suppression, localization precision, and temporal resolution achievable with pure scattering-based imaging and tracking of nanoparticles at interfaces.

Concentrations, distribution, and risk assessment of heavy metals in the iron tailings of Yeshan National Mine Park in Nanjing, China

For the first time, a field survey was conducted to investigate the present situation, vertical distribution and ecological risks of heavy metals (Cu, Zn, Mn, Cr, Pb and As) from 21 in-situ samples drilled out from Yeshan iron mine tailings in the Jiangsu Province of China. The heavy metal contents obtained for the tailing wastes in decreasing order were as follows: Mn > Cu > Zn > As > Cr > Pb. The contents of heavy metals varied with depth, and the variation trends were not completely consistent. Vertical distribution profiles showed that heavy metals accumulated in certain strata. Both the monomial potential ecological risk factor (E) and the risk quotient (RQ) showed a high ecological risk for Cu, Mn and As. The comprehensive ecological risk index (RI) also indicated that the wastes presented a high ecological risk level, to which Cu, Mn and As were the key contributors. Our study showed that the health of individuals, especially children, living in the mining-impacted areas could be affected by the potential noncarcinogenic risk of copper, manganese and the carcinogenic risk of arsenic.

Application of the Spider Limb Positioner to Subscapular System Free Flaps

OBJECTIVE

To demonstrate the application and surgical time savings of the Spider Limb Positioner for subscapular system free flaps in head and neck reconstructive surgery.

METHODS

Single institution retrospective chart review and analysis of patients between 2011 and 2019 that underwent a subscapular system free flap either with or without use of the Spider Limb Positioner. One hundred five patients in total were reviewed with 53 patients in the Spider group. The surgical times were compared between the two groups. Patient-specific information regarding average age, laterality of donor site, recipient site, gender, and flap type were reviewed.

RESULTS

Forty-one patients in both groups underwent a latissimus free flap. Twelve of 53 in the Spider group and 11/52 in the control group underwent a scapula free flap. The average age in the Spider group at the time of surgery was 64 years. The recipient sites for the Spider groups were reviewed. The free flap was ipsilateral to the defect in 81% of cases. The mean surgical time for the 105 patients without the Spider was 568 minutes versus 486 minutes with a Spider P-value of .003478.

CONCLUSION

Use of the Spider Limb Positioner allows for a simultaneous two-team approach during free flap elevation of the subscapular system, which eliminates both dependence on an assistant to support the arm and time consuming positioning changes during flap elevation.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:525-528, 2021.

Management of the Acute Loss of a Free Flap to the Head and Neck-A Multi-institutional Review

OBJECTIVES/HYPOTHESIS

To review the management of failed free tissue transfers among four large institutions over a 13-year period to provide data and analysis for a logical, algorithmic, experience-based approach to the management of failed free flaps.

STUDY DESIGN

Retrospective case series.

METHODS

A multi-institutional retrospective chart review of free tissue transfers to the head and neck region between 2006 and 2019 was performed. Patients with a failed free flap during their hospitalization after surgery to the head and neck were identified and reviewed. Patient age, co-morbidities, risk factors, flap characteristics, tumor specifics, and length of hospital stay were reviewed, collected, and analyzed.

RESULTS

One hundred eighteen flap failures met criteria. The most common failed flap in this review was the osteocutaneous flap 52/118 (44%). The recipient site of the initial free flap (P < .001) was the only statistically significant parameter strongly correlated with management. Osteocutaneous flap failures, fasciocutaneous, bowel, and muscle-only flaps tended to be managed most commonly with a second free flap. Myocutaneous flap failures were managed equally with either a second free flap or a regional flap.

CONCLUSIONS

The most important factor in management of a failed free flap is the recipient site. A second free flap is often the preferred treatment, but in the acute setting, local or regional flaps may be viable options depending on the recipient site, circumstances of flap loss, and patient- specific comorbidities. An algorithm for management of the acute flap loss is presented in this review.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:518-524, 2021.

Myosin II Filament Dynamics in Actin Networks Revealed with Interferometric Scattering Microscopy

The plasma membrane and the underlying cytoskeletal cortex constitute active platforms for a variety of cellular processes. Recent work has shown that the remodeling acto-myosin network modifies local membrane organization, but the molecular details are only partly understood because of difficulties with experimentally accessing the relevant time and length scales. Here, we use interferometric scattering microscopy to investigate a minimal acto-myosin network linked to a supported lipid bilayer membrane. Using the magnitude of the interferometric contrast, which is proportional to molecular mass, and fast acquisition rates, we detect and image individual membrane-attached actin filaments diffusing within the acto-myosin network and follow individual myosin II filament dynamics. We quantify myosin II filament dwell times and processivity as functions of ATP concentration, providing experimental evidence for the predicted ensemble behavior of myosin head domains. Our results show how decreasing ATP concentrations lead to both increasing dwell times of individual myosin II filaments and a global change from a remodeling to a contractile state of the acto-myosin network.

Deep Transfer Learning and Radiomics Feature Prediction of Survival of Patients with High-Grade Gliomas

BACKGROUND AND PURPOSE

Patient survival in high-grade glioma remains poor, despite the recent developments in cancer treatment. As new chemo-, targeted molecular, and immune therapies emerge and show promising results in clinical trials, image-based methods for early prediction of treatment response are needed. Deep learning models that incorporate radiomics features promise to extract information from brain MR imaging that correlates with response and prognosis. We report initial production of a combined deep learning and radiomics model to predict overall survival in a clinically heterogeneous cohort of patients with high-grade gliomas.

MATERIALS AND METHODS

Fifty patients with high-grade gliomas from our hospital and 128 patients with high-grade glioma from The Cancer Genome Atlas were included. For each patient, we calculated 348 hand-crafted radiomics features and 8192 deep features generated by a pretrained convolutional neural network. We then applied feature selection and Elastic Net-Cox modeling to differentiate patients into long- and short-term survivors.

RESULTS

In the 50 patients with high-grade gliomas from our institution, the combined feature analysis framework classified the patients into long- and short-term survivor groups with a log-rank test P value < .001. In the 128 patients from The Cancer Genome Atlas, the framework classified patients into long- and short-term survivors with a log-rank test P value of .014. For the mixed cohort of 50 patients from our institution and 58 patients from The Cancer Genome Atlas, it yielded a log-rank test P value of .035.

CONCLUSIONS

A deep learning model combining deep and radiomics features can dichotomize patients with high-grade gliomas into long- and short-term survivors.

Adjuvant bevacizumab for melanoma patients at high risk of recurrence: survival analysis of the AVAST-M trial

Background

Bevacizumab is a recombinant humanised monoclonal antibody to vascular endothelial growth factor shown to improve survival in advanced solid cancers. We evaluated the role of adjuvant bevacizumab in melanoma patients at high risk of recurrence.

Patients and methods

Patients with resected AJCC stage IIB, IIC and III cutaneous melanoma were randomised to receive either adjuvant bevacizumab (7.5 mg/kg i.v. 3 weekly for 1 year) or standard observation. The primary end point was detection of an 8% difference in 5-year overall survival (OS) rate; secondary end points included disease-free interval (DFI) and distant metastasis-free interval (DMFI). Tumour and blood were analysed for prognostic and predictive markers.

Results

Patients (n=1343) recruited between 2007 and 2012 were predominantly stage III (73%), with median age 56 years (range 18–88 years). With 6.4-year median follow-up, 515 (38%) patients had died [254 (38%) bevacizumab; 261 (39%) observation]; 707 (53%) patients had disease recurrence [336 (50%) bevacizumab, 371 (55%) observation]. OS at 5 years was 64% for both groups [hazard ratio (HR) 0.98; 95% confidence interval (CI) 0.82–1.16, P = 0.78). At 5 years, 51% were disease free on bevacizumab versus 45% on observation (HR 0.85; 95% CI 0.74–0.99, P = 0.03), 58% were distant metastasis free on bevacizumab versus 54% on observation (HR 0.91; 95% CI 0.78–1.07, P = 0.25). Forty four percent of 682 melanomas assessed had a BRAF^V600 mutation. In the observation arm, BRAF mutant patients had a trend towards poorer OS compared with BRAF wild-type patients (P = 0.06). BRAF mutation positivity trended towards better OS with bevacizumab (P = 0.21).

Conclusions

Adjuvant bevacizumab after resection of high-risk melanoma improves DFI, but not OS. BRAF mutation status may predict for poorer OS untreated and potential benefit from bevacizumab.

Clinical Trial Information

ISRCTN 81261306; EudraCT Number: 2006-005505-64

Predictive impact of rare genomic copy number variations in siblings of individuals with autism spectrum disorders

Identification of genetic biomarkers associated with autism spectrum disorders (ASDs) could improve recurrence prediction for families with a child with ASD. Here, we describe clinical microarray findings for 253 longitudinally phenotyped ASD families from the Baby Siblings Research Consortium (BSRC), encompassing 288 infant siblings. By age 3, 103 siblings (35.8%) were diagnosed with ASD and 54 (18.8%) were developing atypically. Thirteen siblings have copy number variants (CNVs) involving ASD-relevant genes: 6 with ASD, 5 atypically developing, and 2 typically developing. Within these families, an ASD-related CNV in a sibling has a positive predictive value (PPV) for ASD or atypical development of 0.83; the Simons Simplex Collection of ASD families shows similar PPVs. Polygenic risk analyses suggest that common genetic variants may also contribute to ASD. CNV findings would have been pre-symptomatically predictive of ASD or atypical development in 11 (7%) of the 157 BSRC siblings who were eventually diagnosed clinically.

Dissecting FOXP2 Oligomerization and DNA Binding

Protein–protein and protein–substrate interactions are critical to function and often depend on factors that are difficult to disentangle. Herein, a combined biochemical and biophysical approach, based on electrically switchable DNA biochips and single‐molecule mass analysis, was used to characterize the DNA binding and protein oligomerization of the transcription factor, forkhead box protein P2 (FOXP2). FOXP2 contains domains commonly involved in nucleic‐acid binding and protein oligomerization, such as a C₂H₂‐zinc finger (ZF), and a leucine zipper (LZ), whose roles in FOXP2 remain largely unknown. We found that the LZ mediates FOXP2 dimerization via coiled‐coil formation but also contributes to DNA binding. The ZF contributes to protein dimerization when the LZ coiled‐coil is intact, but it is not involved in DNA binding. The forkhead domain (FHD) is the key driver of DNA binding. Our data contributes to understanding the mechanisms behind the transcriptional activity of FOXP2.

Interferometric Scattering Microscopy

Interferometric scattering microscopy (iSCAT) is an extremely sensitive imaging method based on the efficient detection of light scattered by nanoscopic objects. The ability to, at least in principle, maintain high imaging contrast independent of the exposure time or the scattering cross section of the object allows for unique applications in single-particle tracking, label-free imaging of nanoscopic (dis)assembly, and quantitative single-molecule characterization. We illustrate these capabilities in areas as diverse as mechanistic studies of motor protein function, viral capsid assembly, and single-molecule mass measurement in solution. We anticipate that iSCAT will become a widely used approach to unravel previously hidden details of biomolecular dynamics and interactions.

Multiscale analyses reveal native-like lamellar bone repair and near perfect bone-contact with porous strontium-loaded bioactive glass

The efficient healing of critical-sized bone defects using synthetic biomaterial-based strategies is promising but remains challenging as it requires the development of biomaterials that combine a 3D porous architecture and a robust biological activity. Bioactive glasses (BGs) are attractive candidates as they stimulate a biological response that favors osteogenesis and vascularization, but amorphous 3D porous BGs are difficult to produce because conventional compositions crystallize during processing. Here, we rationally designed a porous, strontium-releasing, bioactive glass-based scaffold (pSrBG) whose composition was tailored to deliver strontium and whose properties were optimized to retain an amorphous phase, induce tissue infiltration and encourage bone formation. The hypothesis was that it would allow the repair of a critical-sized defect in an ovine model with newly-formed bone exhibiting physiological matrix composition and structural architecture. Histological and histomorphometric analyses combined with indentation testing showed pSrBG encouraged near perfect bone-to-material contact and the formation of well-organized lamellar bone. Analysis of bone quality by a combination of Raman spectral imaging, small-angle X-ray scattering, X-ray fluorescence and focused ion beam-scanning electron microscopy demonstrated that the repaired tissue was akin to that of normal, healthy bone, and incorporated small amounts of strontium in the newly formed bone mineral. These data show the potential of pSrBG to induce an efficient repair of critical-sized bone defects and establish the importance of thorough multi-scale characterization in assessing biomaterial outcomes in large animal models.

Do Integrated Systems of Stroke Care Improve Symptom to Surgery Times in Patients with Symptomatic Carotid Stenosis? A Single Centre Decision Tree Analysis

OBJECTIVE

The objective of this study was to examine the impact of an integrated system of stroke care on symptom to surgery times, cost-effectiveness, and quality of life measures in patients with symptomatic carotid stenosis.

METHODS

Patients who underwent carotid endarterectomy (CEA) in a regional vascular centre between April 1, 2011, and March 31, 2016, were identified from the National Vascular Registry (NVR). Risk of stroke on medical therapy for each patient was calculated using the Oxford stroke risk calculator. Symptom to surgery times were compared among patients referred from a stroke service providing an integrated stroke care and the stroke service in an adjacent NHS trust which provides standard urgent referral pathway. A decision analytic Markov process model was constructed to determine the cost-effectiveness of CEA versus medical treatment in patients who followed the standard and integrated pathways. This model examined the lifetime costs and health benefits of CEA through each pathway.

RESULTS

A total of 376 patients underwent CEA, of whom 243 were managed through the integrated stroke pathway and 133 through the standard urgent referral pathway. Median symptom to surgery time was 11 (0-66) days for the former and 15 (3-90) days for the latter (p < .001). There was no significant difference in peri-operative stroke death rate between integrated (2.1%) and standard (1.5%) pathways (chi-square = 0.14, p = .73). CEA through the integrated pathway improved quality adjusted life expectancy by an additional 0.13 (0.64 QALYs [integrated pathway] to 0.51 QALYs [standard pathway]) and was associated with an incremental lifetime cost benefit of £2203.4.

CONCLUSIONS

An integrated stroke system of care is cost-effective and associated with significant improvements in quality adjusted life years.

Quantitative mass imaging of single biological macromolecules

The cellular processes underpinning life are orchestrated by proteins and their interactions. The associated structural and dynamic heterogeneity, despite being key to function, poses a fundamental challenge to existing analytical and structural methodologies. We used interferometric scattering microscopy to quantify the mass of single biomolecules in solution with 2% sequence mass accuracy, up to 19-kilodalton resolution, and 1-kilodalton precision. We resolved oligomeric distributions at high dynamic range, detected small-molecule binding, and mass-imaged proteins with associated lipids and sugars. These capabilities enabled us to characterize the molecular dynamics of processes as diverse as glycoprotein cross-linking, amyloidogenic protein aggregation, and actin polymerization. Interferometric scattering mass spectrometry allows spatiotemporally resolved measurement of a broad range of biomolecular interactions, one molecule at a time.

Pharmacokinetic modelling and validation of the half-life extension needed to reduce the burden of infusions compared with standard factor VIII

INTRODUCTION

Currently, no universally accepted definition of extended half-life (EHL) recombinant FVIII (rFVIII) exists. Identifying the minimum half-life extension ratio required for a reduction in dosing frequency compared with standard rFVIII could enable a more practical approach to decisions around prophylaxis with EHL rFVIII.

AIM

To identify the half-life extension ratio required to decrease rFVIII dosing frequency by at least 1 day while maintaining the proportion of patients with plasma rFVIII levels above 1 IU/dL and without increasing the total weekly dose.

METHODS

A previously published population pharmacokinetic model for standard rFVIII was used to estimate the percentage of patients with factor VIII (FVIII) levels always >1 IU/dL using various benchmark regimens. Using modelling, dosing frequency was reduced while rFVIII half-life was extended until the percentage of patients with FVIII >1 IU/dL equalled that of the benchmark regimen.

RESULTS

Benchmark 3×/wk dosing totalling 100 IU/kg/wk of rFVIII resulted in 56.6% of patients with FVIII levels always >1 IU/dL. With 2×/wk dosing, totalling 80 or 90 IU/kg/wk, half-life extensions required to maintain 56.6% of patients at FVIII levels >1 IU/dL were 1.30 and 1.26, respectively. A half-life extension ratio of 1.33 was required to change dosing from every 48 hours to every 72 hours (both at 105 IU/kg/wk) while maintaining 92.8% of patients with FVIII >1 IU/dL.

CONCLUSION

Based on this investigation, EHL rFVIII products should have a minimum half-life extension ratio of 1.3 to provide a reduction in dosing frequency from 3× to 2×/wk compared with standard rFVIII products while maintaining the same minimum FVIII trough level.

Abstract P6-12-02: Racial/ethnic differences in sleep quality and duration among breast cancer survivors: Results from the women's health initiative (WHI)

BACKGROUND: Sleep is a crucial factor for optimal health, but breast cancer survivors often report poor sleep quality. It is estimated 20-70% of survivors have at least one sleep problem, which contribute to quality of life and health differences among survivors. Minority groups tend to have poorer sleep quality and shorter sleep duration than Non-Hispanic Whites (NHW). African-Americans (AA) with breast cancer have a poorer prognosis than NHW for each stage-specific diagnosis and are twice as likely as NHW to report short sleep duration, yet survivor studies are still lacking in AA participants. The purpose of this study was to examine sleep quality and duration patterns before and after cancer diagnosis by race/ethnicity among WHI breast cancer survivors.

METHODS: There were 12,098 postmenopausal women diagnosed with invasive breast cancer after WHI enrollment who were eligible for this secondary analysis. Baseline demographic and clinical characteristics were described. The WHI Insomnia Rating Scale (WHIIRS) was measured at multiple time points pre- and post-diagnosis. A higher WHIIRS scores (0-20 points) indicates greater sleep disturbance and ≥9 points identifies clinical insomnia. A linear mixed model was fit to the WHIIRS sleep quality data to examine if the trend in sleep quality with time changed following a cancer diagnosis. For short (&lt;6hrs) and long (≥9hrs) sleep duration, we fit a logistic regression model with multilevel mixed effects.

RESULTS: The majority of participants were NHW (87.4%), mean age at diagnosis was 70.3 years, and 75% had localized breast cancer at diagnosis. At baseline, 30% of women had insomnia. The lowest average WHIIRS score was 5.6 among Asians, and the highest was 6.6 among American-Indians and NHWs (p=0.02). AAs had the most women sleeping ≤5 hrs/night and NHW had the least (19.6% vs 5.7%, p&lt;0.01). At diagnosis, the average WHIIRS score was 7.2. After diagnosis, sleep quality improved in the overall study population (p=0.03). Short sleep duration ranged from 6% before diagnosis, 9% at diagnosis and 11% after diagnosis (p=0.29). Long sleep duration ranged from 3% before diagnosis, 6% at diagnosis and 15% after diagnosis (p=0.43). There was no difference in sleep quality across race after diagnosis (p=0.53). The probability of short sleep and long sleep after diagnosis did not differ significantly across race (p=0.12, p=0.90), however racial minorities tended to have higher probabilities of short sleep at diagnosis compared to NHWs.

DISCUSSION: Sleep is an appealing area to target for improvement due to the multiple ways it can be treated. With increasing survival rates, there is an emphasis on improving quality of life in survivors. Our results span 20 years pre-diagnosis to 15 years post-diagnosis and are similar to shorter follow-up studies which found most women's sleep problems resolve within a few years of treatment completion. The lack of difference by race was an unexpected finding in another similar longitudinal study, which suggested most differences are seen in cross-sectional sleep studies. This study adds to the literature on longitudinal sleep data, especially to the little data on sleep trajectories in minority breast cancer survivors.

Citation Format: Beverly CM, Naughton M, Foraker R, Pennell M, Young G, Hale L, Crane T, Pan K, Danhauer S, Feliciano E, Paskett E. Racial/ethnic differences in sleep quality and duration among breast cancer survivors: Results from the women's health initiative (WHI) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-12-02.

A Database Built Upon the Medical Event Vector

PHAMIS is an automated medical information system designed to provide long-term storage and retrieval of clinical information about Public Health Service patients. The patient database is composed of clinical events stored in compact format as multidimensional vectors in a write-once, read-only file to minimize file maintenance. Clinical observations are recorded as pointers to a large and expandable dictionary, rather than as text, to reduce storage requirements. The database design includes both within-patient-record and between-patient-recorcl indexes to speed data retrieval and facilitate report generation.

Clinical use of recombinant factor VIII Fc and recombinant factor IX Fc in patients with haemophilia A and B

INTRODUCTION

Although clinical trials have demonstrated extended half-life (EHL) VIII and IX fusion proteins to be safe and efficacious in patients with haemophilia A and B, studies on real-world clinical application have not been performed.

AIM

To retrospectively examine the real-world experience of rFVIII Fc and rFIX Fc in patients.

METHODS

A retrospective review of existing medical records of patients with haemophilia A or haemophilia B who had been prescribed rFVIII Fc or rFIX Fc was conducted from the Children's Hospital Los Angeles Haemostasis and Thrombosis Centre database.

RESULTS

A total of 36 male subjects enroled in the study (17 patients with haemophilia A and 19 patients with haemophilia B; 0-18 years of age, N = 27; >18 years of age, N = 9). Patients had a reduction of their ABR and AJBR following initiation of EHL factors. For patients with haemophilia A, the ABR and ABJR fell from 2.3 and 1.8 to 1.3 and 0.71, respectively. For patients with haemophilia B, the ABR and ABJR fell from 2.5 and 2.1 to 0.82 and 0.37, respectively. Five of 36 patients reverted from EHL back to standard half-life (SHL) factor treatment. Overall, treatment with EHL factors reduced factor consumption by nearly half compared to treatment with SHL factors in patients with haemophilia B.

CONCLUSION

This study demonstrates the largely successful transition of 36 patients from SHL to EHL factor products.