Measurement of left atrial size as a predictor of severity of illness in sickle cell disease.

BACKGROUND: Sickle cell disease (SCD) is characterized by microvascular occlusion which leads to multiorgan damage, including left ventricular diastolic dysfunction. Left ventricular diastolic dysfunction has been shown to be an independent risk factor for death in SCD patients. Left atrial dilation (LAD) has been used as a surrogate marker for identification of left ventricular diastolic dysfunction. OBJECTIVE: Investigate the association of LAD, as determined by echocardiography, with increased disease burden in SCD as reflected by increased emergency department (ED) utilization, increased hemolysis markers, and worsening anemia. METHODS: A retrospective cohort study of patients from a single university hospital were selected from a national registry. Age, sickle cell phenotype, echocardiogram findings, ED utilization, baseline hemoglobin, and lab values needed for calculation of hemolytic index were recorded for each patient. Patients were then stratified into two distinct groups based on the presence or absence of LAD to compare ED utilization, baseline hemoglobin and hemolytic index between the two groups. RESULTS: 129 patients met the criteria for inclusion with 88 having normal left atrial volume and 41 with LAD. There was a higher percentage of high ED utilizers in the LAD group compared to the normal left atrial volume group [34% vs. 17%, p = 0.03]. Average hemoglobin was lower in the LAD group compared with the normal left atrial volume group [mean 8.57 g/dL vs. 9.47 g/dL, p = 0.011]. The mean hemolytic index was higher in the LAD group when compared with the normal left atrial volume group [0.44 vs. -0.21, p < 0.001]. CONCLUSIONS: LAD was associated with higher ED utilization, lower hemoglobin level, and more hemolysis in patients with SCD.

Social determinants of health and treatment center affiliation: analysis from the sickle cell disease implementation consortium registry.

BACKGROUND: Adults with sickle cell disease (SCD) suffer early mortality and high morbidity. Many are not affiliated with SCD centers, defined as no ambulatory visit with a SCD specialist in 2 years. Negative social determinants of health (SDOH) can impair access to care. HYPOTHESIS: Negative SDOH are more likely to be experienced by unaffiliated adults than adults who regularly receive expert SCD care. METHODS: Cross-sectional analysis of the SCD Implementation Consortium (SCDIC) Registry, a convenience sample at 8 academic SCD centers in 2017-2019. A Distressed Communities Index (DCI) score was assigned to each registry member's zip code. Insurance status and other barriers to care were self-reported. Most patients were enrolled in the clinic or hospital setting. RESULTS: The SCDIC Registry enrolled 288 Unaffiliated and 2110 Affiliated SCD patients, ages 15-45y. The highest DCI quintile accounted for 39% of both Unaffiliated and Affiliated patients. Lack of health insurance was reported by 19% of Unaffiliated versus 7% of Affiliated patients. The most frequently selected barriers to care for both groups were "previous bad experience with the healthcare system" (40%) and "Worry about Cost" (17%). SCD co-morbidities had no straightforward trend of association with Unaffiliated status. The 8 sites' results varied. CONCLUSION: The DCI economic measure of SDOH was not associated with Unaffiliated status of patients recruited in the health care delivery setting. SCDIC Registrants reside in more distressed communities than other Americans. Other SDOH themes of affordability and negative experiences might contribute to Unaffiliated status. Recruiting Unaffiliated SCD patients to care might benefit from systems adopting value-based patient-centered solutions.

"The project did not come to us with a solution": Perspectives of research teams on implementing a study about electronic health record-embedded individualized pain plans for emergency department treatment of vaso-occlusive episodes in adults with sickle cell disease.

BACKGROUND: This study aimed to capture the implementation process of the ALIGN Study, (An individualized Pain Plan with Patient and Provider Access for Emergency Department care of Sickle Cell Disease). ALIGN aimed to embed Individualized Pain Plans in the electronic health record (E-IPP) and provide access to the plan for both adult patients with sickle cell disease (SCD) and emergency department providers when a person with SCD comes to the emergency department in vaso-occlusive crises. METHODS: Semi-structured interviews were conducted with research teams from the 8 participating sites from the ALIGN study. Seventeen participants (principal investigators and study coordinators) shared their perspectives about the implementation of ALIGN in their sites. Data were analyzed in three phases using open coding steps adapted from grounded theory and qualitative content analysis. RESULTS: A total of seven overarching themes were identified: (1) the E-IPP structure (location and upkeep) and collaboration with the informatics team, (2) the role of ED champion, (3) the role of research coordinators, (4) research team communication, and communication between research team and clinical team, (5) challenges with the study protocol, (6) provider feedback: addressing over-utilizers, patient mistrust, and the positive feedback about the intervention, and (7) COVID-19 and its effects on study implementation. CONCLUSIONS: Findings from this study contribute to learning how to implement E-IPPs for adult patients with SCD in ED. The study findings highlight the importance of early engagement with different team members, a champion from the emergency department, study coordinators with different skills and enhancement of communication and trust among team members. Further recommendations are outlined for hospitals aiming to implement E-IPP for patients with SCD in ED.

Charge-Disproportionation Symmetry Breaking Creates a Heterodimeric Myoglobin Complex with Enhanced Affinity and Rapid Intracomplex Electron Transfer.

We report rapid photoinitiated intracomplex electron transfer (ET) within a "charge-disproportionated" myoglobin (Mb) dimer with greatly enhanced affinity. Two mutually supportive Brownian Dynamics (BD) interface redesign strategies, one a new "heme-filtering" approach, were employed to "break the symmetry" of a Mb homodimer by pairing Mb constructs with complementary highly positive and highly negative net surface charges, introduced through D/E → K and K → E mutations, respectively. BD simulations using a previously developed positive mutant, Mb(+6) = Mb(D44K/D60K/E85K), led to construction of the complementary negative mutant Mb(-6) = Mb(K45E, K63E, K95E). Simulations predict the pair will form a well-defined complex comprising a tight ensemble of conformations with nearly parallel hemes, at a metal-metal distance ∼18-19 Å. Upon expression and X-ray characterization of the partners, BD predictions were verified through ET photocycle measurements enabled by Zn-deuteroporphyrin substitution, forming the [ZnMb(-6), Fe(3+)Mb(+6)] complex. Triplet ET quenching shows charge disproportionation increases the binding constant by no less than ∼5 orders of magnitude relative to wild-type Mb values. All progress curves for charge separation (CS) and charge recombination (CR) are reproduced by a generalized kinetic model for the interprotein ET photocycle. The intracomplex ET rate constants for both CS and CR are increased by over 5 orders of magnitude, and their viscosity independence is indicative of true interprotein ET, rather than dynamic gating as seen in previous studies. The complex displays an unprecedented timecourse for CR of the CS intermediate I. After a laser flash, I forms through photoinduced CS, accumulates to a maximum concentration, then dies away through CR. However, before completely disappearing, I reappears without another flash and reaches a second maximum before disappearing completely.

Recruitment Strategies in the Integration of Mobile Health Into Sickle Cell Disease Care to Increase Hydroxyurea Utilization Study (meSH): Multicenter Survey Study.

BACKGROUND: Hydroxyurea is an evidence-based disease-modifying therapy for sickle cell disease (SCD) but is underutilized. The Integration of Mobile Health into Sickle Cell Disease Care to Increase Hydroxyurea Utilization (meSH) multicenter study leveraged mHealth to deliver targeted interventions to patients and providers. SCD studies often underenroll; and recruitment strategies in the SCD population are not widely studied. Unanticipated events can negatively impact enrollment, making it important to study strategies that ensure adequate study accrual. OBJECTIVE: The goal of this study was to evaluate enrollment barriers and the impact of modified recruitment strategies among patients and providers in the meSH study in response to a global emergency. METHODS: Recruitment was anticipated to last 2 months for providers and 6 months for patients. The recruitment strategies used with patients and providers, new recruitment strategies, and recruitment rates were captured and compared. To document recruitment adaptations and their reasons, study staff responsible for recruitment completed an open-ended 9-item questionnaire eliciting challenges to recruitment and strategies used. Themes were extrapolated using thematic content analysis. RESULTS: Total enrollment across the 7 sites included 89 providers and 293 patients. The study acceptance rate was 85.5% (382/447) for both patients and providers. The reasons patients declined participation were most frequently a lack of time and interest in research, while providers mostly declined because of self-perceived high levels of SCD expertise, believing they did not need the intervention. Initially, recruitment involved an in-person invitation to participate during clinic visits (patients), staff meetings (providers), or within the office (providers). We identified several important recruitment challenges, including (1) lack of interest in research, (2) lack of human resources, (3) unavailable physical space for recruitment activities, and (4) lack of documentation to verify eligibility. Adaptive strategies were crucial to alleviate enrollment disruptions due to the COVID-19 pandemic. These included remote approaching and consenting (eg, telehealth, email, and telephone) for patients and providers. Additionally, for patients, recruitment was enriched by simplification of enrollment procedures (eg, directly approaching patients without a referral from the provider) and a multitouch method (ie, warm introductions with flyers, texts, and patient portal messages). We found that patient recruitment rates were similar between in-person and adapted (virtual with multitouch) approaches (167/200, 83.5% and 126/143, 88.1%, respectively; P=.23). However, for providers, recruitment was significantly higher for in-person vs remote recruitment (48/50, 96% and 41/54, 76%, respectively, P<.001). CONCLUSIONS: We found that timely adaptation in recruitment strategies secured high recruitment rates using an assortment of enriched remote recruitment strategies. Flexibility in approach and reducing the burden of enrollment procedures for participants aided enrollment. It is important to continue identifying effective recruitment strategies in studies involving patients with SCD and their providers and the impact and navigation of recruitment challenges. TRIAL REGISTRATION: ClinicalTrials.Gov NCT03380351; https://clinicaltrials.gov/study/NCT03380351. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.2196/16319.

Evolving the [myoglobin, cytochrome b(5)] complex from dynamic toward simple docking: charging the electron transfer reactive patch.

We describe photoinitiated electron transfer (ET) from a suite of Zn-substituted myoglobin (Mb) variants to cytochrome b(5) (b(5)). An electrostatic interface redesign strategy has led to the introduction of positive charges into the vicinity of the heme edge through D/E → K charge-reversal mutation combinations at "hot spot" residues (D44, D60, and E85), augmented by the elimination of negative charges from Mb or b(5) by neutralization of heme propionates. These variations create an unprecedentedly large range in the product of the ET partners' total charges (-5 < -q(Mb)q(b(5)) < 40). The binding affinity (K(a)) increases 1000-fold as -q(Mb)q(b(5)) increases through this range and exhibits a surprisingly simple, exponential dependence on -q(Mb)q(b(5)). This is explained in terms of electrostatic interactions between a "charged reactive patch" (crp) on each partner's surface, defined as a compact region around the heme edge that (i) contains the total protein charge of each variant and (ii) encompasses a major fraction of the "reactive region" (Rr) comprising surface atoms with large matrix elements for electron tunneling to the heme. As -q(Mb)q(b(5)) increases, the complex undergoes a transition from fast to slow-exchange dynamics on the triplet ET time scale, with a correlated progression in the rate constants for intracomplex (k(et)) and bimolecular (k(2)) ET. This progression is analyzed by integrating the crp and Rr descriptions of ET into the textbook steady-state treatment of reversible binding between partners that undergo intracomplex ET and found to encompass the full range of behaviors predicted by the model. The generality of this approach is demonstrated by its application to the extensive body of data for the ET complex between the photosynthetic reaction center and cytochrome c(2). Deviations from this model also are discussed.

Interfacial hydration, dynamics and electron transfer: multi-scale ET modeling of the transient [myoglobin, cytochrome b5] complex.

Formation of a transient [myoglobin (Mb), cytochrome b(5) (cyt b(5))] complex is required for the reductive repair of inactive ferri-Mb to its functional ferro-Mb state. The [Mb, cyt b(5)] complex exhibits dynamic docking (DD), with its cyt b(5) partner in rapid exchange at multiple sites on the Mb surface. A triple mutant (Mb(3M)) was designed as part of efforts to shift the electron-transfer process to the simple docking (SD) regime, in which reactive binding occurs at a restricted, reactive region on the Mb surface that dominates the docked ensemble. An electrostatically-guided brownian dynamics (BD) docking protocol was used to generate an initial ensemble of reactive configurations of the complex between unrelaxed partners. This ensemble samples a broad and diverse array of heme-heme distances and orientations. These configurations seeded all-atom constrained molecular dynamics simulations (MD) to generate relaxed complexes for the calculation of electron tunneling matrix elements (T(DA)) through tunneling-pathway analysis. This procedure for generating an ensemble of relaxed complexes combines the ability of BD calculations to sample the large variety of available conformations and interprotein distances, with the ability of MD to generate the atomic level information, especially regarding the structure of water molecules at the protein-protein interface, that defines electron-tunneling pathways. We used the calculated T(DA) values to compute ET rates for the [Mb(wt), cyt b(5)] complex and for the complex with a mutant that has a binding free energy strengthened by three D/E → K charge-reversal mutations, [Mb(3M), cyt b(5)]. The calculated rate constants are in agreement with the measured values, and the mutant complex ensemble has many more geometries with higher T(DA) values than does the wild-type Mb complex. Interestingly, water plays a double role in this electron-transfer system, lowering the tunneling barrier as well as inducing protein interface remodeling that screens the repulsion between the negatively-charged propionates of the two hemes.

Effective Recruitment Strategies for a Sickle Cell Patient Registry Across Sites from the Sickle Cell Disease Implementation Consortium (SCDIC).

Sickle cell disease (SCD) is a genetic disorder predominantly affecting people of African descent and is associated with significant morbidity and mortality. To improve SCD outcomes, the National Heart Lung and Blood Institute funded eight centers to participate in the SCD Implementation Consortium. Sites were required to each recruit 300 individuals with SCD, over 20 months. We aim to describe recruitment strategies and challenges encountered. Participants aged 15-45 years with confirmed diagnosis of SCD were eligible. Descriptive statistics were used to analyze the effectiveness of each recruitment strategy. A total of 2432 participants were recruited. Majority (95.3%) were African American. Successful strategies were recruitment from clinics (68.1%) and affiliated sites (15.6%). Recruitment at community events, emergency departments and pain centers had the lowest yield. Challenges included saturation of strategies and time constraints. Effective recruitment of participants in multi-site studies requires multiple strategies to achieve adequate sample sizes.

Photoinitiated singlet and triplet electron transfer across a redesigned [myoglobin, cytochrome b5] interface.

We describe a strategy by which reactive binding of a weakly bound, 'dynamically docked (DD)' complex without a known structure can be strengthened electrostatically through optimized placement of surface charges, and discuss its use in modulating complex formation between myoglobin (Mb) and cytochrome b(5) (b(5)). The strategy employs paired Brownian dynamics (BD) simulations, one which monitors overall binding, the other reactive binding, to examine [X --> K] mutations on the surface of the partners, with a focus on single and multiple [D/E --> K] charge reversal mutations. This procedure has been applied to the [Mb, b(5)] complex, indicating mutations of Mb residues D44, D60, and E85 to be the most promising, with combinations of these showing a nonlinear enhancement of reactive binding. A novel method of displaying BD profiles shows that the 'hits' of b(5) on the surfaces of Mb(WT), Mb(D44K/D60K), and Mb(D44K/D60K/E85K) progressively coalesce into two 'clusters': a 'diffuse' cluster of hits that are distributed over the Mb surface and have negligible electrostatic binding energy and a 'reactive' cluster of hits with considerable stability that are localized near its heme edge, with short Fe-Fe distances favorable to electron transfer (ET). Thus, binding and reactivity progressively become correlated by the mutations. This finding relates to recent proposals that complex formation is a two-step process, proceeding through the formation of a weakly bound encounter complex to a well-defined bound complex. The design procedure has been tested through measurements of photoinitiated ET between the Zn-substituted forms of Mb(WT), Mb(D44K/D60K), and Mb(D44K/D60K/E85K) and Fe(3+)b(5). Both mutants convert the complex from the DD regime exhibited by Mb(WT), in which the transient complex is in fast kinetic exchange with its partners, k(off) >> k(et), to the slow-exchange regime, k(et) >> k(off), and both mutants exhibit rapid intracomplex ET from the triplet excited state to Fe(3+)b(5) (rate constant, k(et) approximately 10(6) s(-1)). The affinity constants of the mutant Mbs cannot be derived through conventional analysis procedures because intracomplex singlet ET quenching causes the triplet-ground absorbance difference to progressively decrease during a titration, but this effect has been incorporated into a new procedure for computing binding constants. Most importantly, these measurements reveal the presence of fast photoinduced singlet ET across the protein-protein interface, (1)k(et) approximately 2 x 10(8) s(-1).

Electrostatic redesign of the [myoglobin, cytochrome b5] interface to create a well-defined docked complex with rapid interprotein electron transfer.

Cyt b(5) is the electron-carrier "repair" protein that reduces met-Mb and met-Hb to their O(2)-carrying ferroheme forms. Studies of electron transfer (ET) between Mb and cyt b(5) revealed that they react on a "Dynamic Docking" (DD) energy landscape on which binding and reactivity are uncoupled: binding is weak and involves an ensemble of nearly isoenergetic configurations, only a few of which are reactive; those few contribute negligibly to binding. We set the task of redesigning the surface of Mb so that its reaction with cyt b(5) instead would occur on a conventional "simple docking" (SD) energy landscape, on which a complex exhibits a well-defined (set of) reactive binding configuration(s), with binding and reactivity thus no longer being decoupled. We prepared a myoglobin (Mb) triple mutant (D44K/D60K/E85K; Mb(+6)) substituted with Zn-deuteroporphyrin and monitored cytochrome b(5) (cyt b(5)) binding and electron transfer (ET) quenching of the (3)ZnMb(+6) triplet state. In contrast, to Mb(WT), the three charge reversals around the "front-face" heme edge of Mb(+6) have directed cyt b(5) to a surface area of Mb adjacent to its heme, created a well-defined, most-stable structure that supports good ET pathways, and apparently coupled binding and ET: both K(a) and k(et) are increased by the same factor of approximately 2 x 10(2), creating a complex that exhibits a large ET rate constant, k(et) = 10(6 1) s(-1), and is in slow exchange (k(off) << k(et)). In short, these mutations indeed appear to have created the sought-for conversion from DD to simple docking (SD) energy landscapes.