Referral and evaluation for kidney transplantation among patients with lupus nephritis-related end-stage kidney disease.

OBJECTIVE: For the majority of patients with lupus nephritis-related end-stage kidney disease (LN-ESKD), kidney transplant is associated with better outcomes than dialysis. Access to kidney transplant requires an initial referral to a transplant center and medical evaluation prior to waitlisting. The study's objective was to examine access to these early steps in the kidney transplant process among patients with LN-ESKD. METHODS: Adults who began treatment for ESKD in the Southeast, Northeast, New York, or Ohio River Valley U.S. regions from 1/1/2012 to 12/31/2019, followed through 6/30/2021, were identified from the United States Renal Data System. Referral and evaluation start data were collected from 28 of 48 transplant centers across these regions. The exposure was primary cause of ESKD (LN-ESKD vs other-ESKD). The outcomes were referral and evaluation start at a transplant center. Cox models quantified the association between LN-ESKD (vs other-ESKD) and referral and evaluation start. RESULTS: Among 192,318 patients initiating treatment for ESKD, 0.4% had LN-ESKD. Over half (58%) of LN-ESKD patients were referred before study end, and among those referred, 66% started the evaluation. In adjusted analyses, patients with LN-ESKD were referred (HR: 1.09, 95% CI: 0.99, 1.19) and started the transplant evaluation (HR: 1.13, 95% CI: 1.00, 1.28) at a higher rate than patients with other-ESKD. Among referred patients with LN-ESKD, the median time from ESKD start to referral was 2.9 months (IQR: <1 to 11.7 months), which is similar to patients with other-ESKD (median 2.6 months, IQR: <1 to 8.8 months). CONCLUSIONS: Among incident patients with ESKD, having a primary diagnosis of LN-ESKD versus other-ESKD is associated with higher rates of early transplant access outcomes. Despite this, patients with LN-ESKD (vs other-ESKD) are less likely to be preemptively referred (i.e., referred prior to ESKD start) for kidney transplant. While providers may no longer be delaying the early steps in the kidney transplantation process among this patient population, there is still room for improvement in the rates of preemptive referral. Access to kidney transplant referral prior to ESKD could result in increased transplant rates and better transplant outcomes for patients with LN-ESKD.

Motor unit firing rate modulation is more impaired during flexion synergy-driven contractions of the biceps brachii in chronic stroke.

Following a hemiparetic stroke, individuals exhibit altered motor unit firing patterns during voluntary muscle contractions, including impairments in firing rate modulation and recruitment. These individuals also exhibit abnormal muscle coactivation through multi-joint synergies (e.g., flexion synergy). Here, we investigate whether motor unit firing activity during flexion synergy-driven contractions of the paretic biceps brachii differs from that of voluntary contractions and use these differences to predict changes in descending motor commands. To accomplish this, we characterized motor unit firing patterns of the biceps brachii in individuals with chronic hemiparetic stroke during voluntary isometric elbow flexion contractions in the paretic and non-paretic limbs, as well as during contractions driven by voluntary effort and by flexion synergy expression in the paretic limb. We observed significant reductions in motor unit firing rate modulation from the non-paretic to paretic limb (non-paretic - paretic: 0.14 pps/%MVT, 95% CI: [0.09 0.19]) that were further reduced during synergy-driven contractions (voluntary paretic - synergy driven: 0.19 pps/%MVT, 95% CI: [0.14 0.25]). Moreover, using recently developed metrics, we evaluated how a stroke-induced reliance on indirect motor pathways alters the inputs that motor units receive and revealed progressive increases in neuromodulatory and inhibitory drive to the motor pool in the paretic limb, with the changes greatest during synergy-driven contractions. These findings suggest that an interplay between heightened neuromodulatory drive and alterations in inhibitory command structure may account for the observed motor unit impairments, further illuminating underlying neural mechanisms involved in the flexion synergy and its impact on motor unit firing patterns post-stroke.

Halogen bonding with carbon: directional assembly of non-derivatised aromatic carbon systems into robust supramolecular ladder architectures.

Carbon, although the central element in organic chemistry, has been traditionally neglected as a target for directional supramolecular interactions. The design of supramolecular structures involving carbon-rich molecules, such as arene hydrocarbons, has been limited almost exclusively to non-directional π-stacking, or derivatisation with heteroatoms to introduce molecular assembly recognition sites. As a result, the predictable assembly of non-derivatised, carbon-only π-systems using directional non-covalent interactions remains an unsolved fundamental challenge of solid-state supramolecular chemistry. Here, we propose and validate a different paradigm for the reliable assembly of carbon-only aromatic systems into predictable supramolecular architectures: not through non-directional π-stacking, but via specific and directional halogen bonding. We present a systematic experimental, theoretical and database study of halogen bonds to carbon-only π-systems (C-I⋯πC bonds), focusing on the synthesis and structural analysis of cocrystals with diversely-sized and -shaped non-derivatised arenes, from one-ring (benzene) to 15-ring (dicoronylene) polycyclic atomatic hydrocarbons (PAHs), and fullerene C60, along with theoretical calculations and a systematic analysis of the Cambridge Structural Database. This study establishes C-I⋯πC bonds as directional interactions to arrange planar and curved carbon-only aromatic systems into predictable supramolecular motifs. In >90% of herein presented structures, the C-I⋯πC bonds to PAHs lead to a general ladder motif, in which the arenes act as the rungs and halogen bond donors as the rails, establishing a unique example of a supramolecular synthon based on carbon-only molecules. Besides fundamental importance in the solid-state and supramolecular chemistry of arenes, this synthon enables access to materials with exciting properties based on simple, non-derivatised aromatic systems, as seen from large red and blue shifts in solid-state luminescence and room-temperature phosphorescence upon cocrystallisation.

Influence of Fluorinated Substituents on the Near-Infrared Phosphorescence of 5d Metallocorroles.

The influence of fluorinated substituents on the luminescent properties of rhenium-oxo, osmium-nitrido, and gold triarylcorroles was studied via a comparison of four ligands: triphenylcorrole (TPC), tris(p-trifluoromethylphenyl)corrole (TpCF3PC), tris{3,5-bis(trifluoromethyl)phenyl}corrole (T3,5-CF3PC), and tris(pentafluorophenyl)corrole (TPFPC). For each metal series examined, fluorinated substituents were found to enhance the luminescent properties, with the phosphorescence quantum yields and triplet decay times increasing in the order TPC < TpCF3PC < T3,5-CF3PC < TPFPC. Among the 11 complexes examined, the highest phosphorescence quantum yield, 2.2%, was recorded for Re[TPFPC](O).

Race, Age, and Kidney Transplant Waitlisting Among Patients Receiving Incident Dialysis in the United States.

Rationale & Objective: Patients with kidney failure from racial and ethnic minority groups and older patients have reduced access to the transplant waitlist relative to White and younger patients. Although racial disparities in the waitlisting group have declined after the 2014 kidney allocation system change, whether there is intersectionality of race and age in waitlisting access is unknown. Study Design: Retrospective cohort study. Setting & Participants: 439,455 non-Hispanic White and non-Hispanic Black US adults initiating dialysis between 2015 and 2019 were identified from the United States Renal Data System, and followed through 2020. Exposures: Patient race and ethnicity (non-Hispanic White and non-Hispanic Black) and age group (18-29, 30-49, 50-64, and 65-80 years). Outcomes: Placement on the United Network for Organ Sharing deceased donor waitlist. Analytical Approach: Age- and race-stratified waitlisting rates were compared. Multivariable Cox proportional hazards models, censored for death, examined the association between race and waitlisting, and included interaction term for race and age. Results: Over a median follow-up period of 1 year, the proportion of non-Hispanic White and non-Hispanic Black patients waitlisted was 20.7% and 20.5%, respectively. In multivariable models, non-Hispanic Black patients were 14% less likely to be waitlisted (aHR, 0.86, 95% CI, 0.77-0.95). Relative differences between non-Hispanic Black and non-Hispanic White patients were different by age group. Non-Hispanic Black patients were 27%, 12%, and 20% less likely to be waitlisted than non-Hispanic White patients for ages 18-29 years (aHR, 0.73; 95% CI, 0.61-0.86), 50-64 (aHR, 0.88; 95% CI, 0.80-0.98), and 65-80 years (aHR, 0.80; 95% CI, 0.71-0.90), respectively, but differences were attenuated among patients aged 30-49 years (aHR, 0.89; 95% CI, 0.77-1.02). Limitations: Race and ethnicity data is physician reported, residual confounding, and analysis is limited to non-Hispanic White and non-Hispanic Black patients. Conclusions: Racial disparities in waitlisting exist between non-Hispanic Black and non-Hispanic White individuals and are most pronounced among younger patients with kidney failure. Results suggest that interventions to address inequalities in waitlisting may need to be targeted to younger patients with kidney failure. Plain-Language Summary: Research has shown that patients from racial and ethnic minority groups and older patients have reduced access to transplant waitlisting relative to White and younger patients; nevertheless, how age impacts racial disparities in waitlisting is unknown. We compared waitlisting between non-Hispanic Black and non-Hispanic White patients with incident kidney failure, within age strata, using registry data for 439,455 US adults starting dialysis (18-80 years) during 2015-2019. Overall, non-Hispanic Black patients were less likely to be waitlisted and relative differences between the two racial groups differed by age. After adjusting for patient-level factors, the largest disparity in waitlisting was observed among adults aged 18-29 years. These results suggest that interventions should target younger adults to reduce disparities in access to kidney transplant waitlisting.

The ASCENT Intervention to Improve Access and Reduce Racial Inequalities in Kidney Waitlisting: A Randomized, Effectiveness-Implementation Trial.

BACKGROUND: The US kidney allocation system (KAS) changed in 2014, but dialysis facility staff (including nephrologists, social workers, nurse managers, and facility administrators) had low awareness of how this policy change could affect their patients' access to transplant. We assessed the effectiveness of a multicomponent and multilevel educational and outreach intervention targeting US dialysis facilities with low waitlisting, with a goal of increasing waitlisting and reducing Black versus White racial disparities in waitlisting. METHODS: The Allocation System Changes for Equity in Kidney Transplantation (ASCENT) study was a cluster-randomized, pragmatic, multilevel, effectiveness-implementation trial including 655 US dialysis facilities with low waitlisting, randomized to receive either the ASCENT intervention (a performance feedback report, a webinar, and staff and patient educational videos) or an educational brochure. Absolute and relative differences in coprimary outcomes (1-year waitlisting and racial differences in waitlisting) were reported among incident and prevalent patients. RESULTS: Among 56,332 prevalent patients, 1-year waitlisting decreased for patients in control facilities (2.72%-2.56%) and remained the same for patients in intervention facilities (2.68%-2.75%). However, the proportion of prevalent Black patients waitlisted in the ASCENT interventions increased from baseline to 1 year (2.52%-2.78%), whereas it remained the same for White patients in the ASCENT intervention facilities (2.66%-2.69%). Among incident patients in ASCENT facilities, 1-year waitlisting increased among Black patients (from 0.87% to 1.07%) but declined among White patients (from 1.54% to 1.27%). Significant racial disparities in waitlisting were observed at baseline, with incident Black patients in ASCENT facilities less likely to waitlist compared with White patients (adjusted odds ratio [aOR], 0.56; 95% confidence interval [CI], 0.35 to 0.92), but 1 year after the intervention, this racial disparity was attenuated (aOR, 0.84; 95% CI, 0.49 to 1.42). CONCLUSIONS: The ASCENT intervention may have a small effect on extending the reach of the new KAS policy by attenuating racial disparities in waitlisting among a population of US dialysis facilities with low waitlisting. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: National Institutes of Health ( NCT02879812 ). PODCAST: This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_03_08_CJN09760822.mp3.

Abnormal synergies and associated reactions post-hemiparetic stroke reflect muscle activation patterns of brainstem motor pathways.

Individuals with moderate-to-severe post-stroke hemiparesis cannot control proximal and distal joints of the arm independently because they are constrained to stereotypical movement patterns called flexion and extension synergies. Accumulating evidence indicates that these synergies emerge because of upregulation of diffusely projecting brainstem motor pathways following stroke-induced damage to corticofugal pathways. During our recent work on differences in synergy expression among proximal and distal joints, we serendipitously observed some notable characteristics of synergy-driven muscle activation. It seemed that: paretic wrist/finger muscles were activated maximally during contractions of muscles at a different joint; differences in the magnitude of synergy expression occurred when elicited via contraction of proximal vs. distal muscles; and associated reactions in the paretic limb occurred during maximal efforts with the non-paretic limb, the strength of which seemed to vary depending on which muscles in the non-paretic limb were contracting. Here we formally investigated these observations and interpreted them within the context of the neural mechanisms thought to underlie stereotypical movement patterns. If upregulation of brainstem motor pathways occurs following stroke-induced corticofugal tract damage, then we would expect a pattern of muscle dependency in the observed behaviors consistent with such neural reorganization. Twelve participants with moderate-to-severe hemiparetic stroke and six without stroke performed maximal isometric torque generation in eight directions: shoulder abduction/adduction and elbow, wrist, and finger flexion/extension. Isometric joint torques and surface EMG were recorded from shoulder, elbow, wrist, and finger joints and muscles. For some participants, joint torque and muscle activation generated during maximal voluntary contractions were lower than during maximal synergy-induced contractions (i.e., contractions about a different joint), particularly for wrist and fingers. Synergy-driven contractions were strongest when elicited via proximal joints and weakest when elicited via distal joints. Associated reactions in the wrist/finger flexors were stronger than those of other paretic muscles and were the only ones whose response depended on whether the non-paretic contraction was at a proximal or distal joint. Results provide indirect evidence linking the influence of brainstem motor pathways to abnormal motor behaviors post-stroke, and they demonstrate the need to examine whole-limb behavior when studying or seeking to rehabilitate the paretic upper limb.

Referral and Evaluation for Kidney Transplantation Following Implementation of the 2014 National Kidney Allocation System.

RATIONALE & OBJECTIVE: The national kidney allocation system (KAS) implemented in December 2014 in the United States redefined the start of waiting time from the time of waitlisting to the time of kidney failure. Waitlisting has declined post-KAS, but it is unknown if this is due to transplant center practices or changes in dialysis facility referral and evaluation. The purpose of this study was to assess the impact of the 2014 KAS policy change on referral and evaluation for transplantation among a population of incident and prevalent patients with kidney failure. STUDY DESIGN: Cohort study. SETTING & PARTICIPANTS: 37,676 incident (2012-2016) patients in Georgia, North Carolina, and South Carolina identified within the US Renal Data System at 9 transplant centers and followed through December 2017. A prevalent population of 6,079 patients from the same centers receiving maintenance dialysis in 2012 but not referred for transplantation in 2012. EXPOSURE: KAS era (pre-KAS vs post-KAS). OUTCOME: Referral for transplantation, start of transplant evaluation, and waitlisting. ANALYTICAL APPROACH: Multivariable time-dependent Cox models for the incident and prevalent population. RESULTS: Among incident patients, KAS was associated with increased referrals (adjusted HR, 1.16 [95% CI, 1.12-1.20]) and evaluation starts among those referred (adjusted HR, 1.16 [95% CI, 1.10-1.21]), decreased overall waitlisting (adjusted HR, 0.70 [95% CI, 0.65-0.76]), and lower rates of active waitlisting among those evaluated compared to the pre-KAS era (adjusted HR, 0.81 [95% CI, 0.74-0.90]). Among the prevalent population, KAS was associated with increases in overall waitlisting (adjusted HR, 1.74 [95% CI, 1.15-2.63]) and active waitlisting among those evaluated (adjusted HR, 2.01 [95% CI, 1.16-3.49]), but had no significant impact on referral or evaluation starts among those referred. LIMITATIONS: Limited to 3 states, residual confounding. CONCLUSIONS: In the southeastern United States, the impact of KAS on steps to transplantation was different among incident and prevalent patients with kidney failure. Dialysis facilities referred more incident patients and transplant centers evaluated more incident patients after implementation of KAS, but fewer evaluated patients were placed onto the waitlist. Changes in dialysis facility and transplant center behaviors after KAS implementation may have influenced the observed changes in access to transplantation.

Facile synthetic routes to bridge-functionalised calix[4]arenes.

Ring-opening of furans at the equatorial methylene bridge positions of a calix[4]arene gives access to a range of new molecules (in good yield) that have widespread potential impact in supramolecular chemistry amongst other areas.

Improving Access to Kidney Transplantation: Perspectives From Dialysis and Transplant Staff in the Southeastern United States.

RATIONALE & OBJECTIVE: There are many barriers to meeting the goal of increasing kidney transplants in the United States. It is important to understand dialysis and transplant center providers' existing practices and identified barriers to increasing the number of dialysis patients who are evaluated for and get wait-listed for a transplant. STUDY DESIGN: Cross-sectional survey of dialysis unit and transplant center staff in End Stage Renal Disease Network 6 (Georgia, North Carolina, South Carolina). SETTING & PARTICIPANTS: Ninety-one transplant staff from all 9 transplant centers in the region and 421 dialysis staff from 421 facilities responded to the survey. PREDICTORS: N/A. OUTCOME: Provider perceptions of barriers faced by patients in the kidney transplant evaluation process and suggestions for improving care. ANALYTICAL APPROACH: Mixed methods. Descriptive analyses of responses to multiple-choice questions and qualitative analysis of open-ended survey responses. RESULTS: The top 5 barriers to kidney transplantation as reported by transplant staff were transportation (63.7%), low health literacy (50.5%), lack of understanding about the transplant process (37.4%), distance to transplant center (29.7%), and low socioeconomic status (28.6%). When asked how dialysis units can help patients complete the evaluation process, the most common responses from transplant center staff were educating patients about transplant (54%), helping patients through steps in the process (35%), and better communication with transplant centers (15%). When dialysis unit staff were asked what could be done to help the facility improve its transplant wait-list rate, the most common responses were educational materials for patients and staff (55%), better communication with transplant centers (12%), and transportation and financial assistance (9%). LIMITATIONS: Survey responses are from 1 end stage renal disease network. CONCLUSIONS: Dialysis units, transplant centers, and ESRD networks can work together to help patients address key barriers to transplantation to improve the country's transplantation rate.

Estimates of persistent inward currents are reduced in upper limb motor units of older adults.

Ageing is a natural process causing alterations in the neuromuscular system, which contributes to reduced quality of life. Motor unit (MU) contributes to weakness, but the mechanisms underlying reduced firing rates are unclear. Persistent inward currents (PICs) are crucial for initiation, gain control and maintenance of motoneuron firing, and are directly proportional to the level of monoaminergic input. Since concentrations of monoamines (i.e. serotonin and noradrenaline) are reduced with age, we sought to determine if estimates of PICs are reduced in older (>60 years old) compared to younger adults (<35 years old). We decomposed MU spike trains from high-density surface electromyography over the biceps and triceps brachii during isometric ramp contractions to 20% of maximum. Estimates of PICs (ΔFrequency; or simply ΔF) were computed using the paired MU analysis technique. Regardless of the muscle, peak firing rates of older adults were reduced by ∼1.6 pulses per second (pps) (P = 0.0292), and ΔF was reduced by ∼1.9 pps (P < 0.0001), compared to younger adults. We further found that age predicted ΔF in older adults (P = 0.0261), resulting in a reduction of ∼1 pps per decade, but there was no relationship in younger adults (P = 0.9637). These findings suggest that PICs are reduced in the upper limbs of older adults during submaximal isometric contractions. Reduced PIC magnitude represents one plausible mechanism for reduced firing rates and function in older individuals, but further work is required to understand the implications in other muscles and during a variety of motor tasks. KEY POINTS: Persistent inward currents play an important role in the neural control of human movement and are influenced by neuromodulation via monoamines originating in the brainstem. During ageing, motor unit firing rates are reduced, and there is deterioration of brainstem nuclei, which may reduce persistent inward currents in alpha motoneurons. Here we show that estimates of persistent inward currents (ΔF) of both elbow flexor and extensor motor units are reduced in older adults. Estimates of persistent inward currents have a negative relationship with age in the older adults, but not in the young. This novel mechanism may play a role in the alteration of motor firing rates that occurs with ageing, which may have consequences for motor control.

Rhenium Corrole Dimers: Electrochemical Insights into the Nature of the Metal-Metal Quadruple Bond.

The interaction of free-base triarylcorroles with Re2(CO)10 in 1,2-dichlorobenzene in the presence of 2,6-lutidine at 180 °C under strict anerobic conditions afforded approximately 10% yields of rhenium corrole dimers. The compounds exhibited diamagnetic 1H NMR spectra consistent with a metal-metal quadruple bond with a σ2π4δ2 orbital occupancy. One of the compounds proved amenable to single-crystal X-ray structure determination, yielding a metal-metal distance of ∼2.24 Å, essentially identical to that in triple-bonded osmium corrole dimers. On the other hand, the electrochemical properties of Re and Os corrole dimers proved to be radically different. Thus, the reduction potentials of the Re corrole dimers are some 800 mV upshifted relative to those of their Os counterparts. Stated differently, the Re corrole dimers are dramatically easier to reduce, reflecting electron addition to δ* versus π* molecular orbitals for Re and Os corrole dimers, respectively. The data also imply electrochemical HOMO-LUMO gaps of only 1.0-1.1 V for rhenium corrole dimers, compared with values of 1.85-1.90 V for their Os counterparts. These HOMO-LUMO gaps rank among the first such values reported for quadruple-bonded transition-metal dimers for any type of supporting ligand, porphyrin-type or not.

Dialysis Facility Profit Status and Early Steps in Kidney Transplantation in the Southeastern United States.

BACKGROUND AND OBJECTIVES: Dialysis facilities in the United States play a key role in access to kidney transplantation. Previous studies reported that patients treated at for-profit facilities are less likely to be waitlisted and receive a transplant, but their effect on early steps in the transplant process is unknown. The study's objective was to determine the association between dialysis facility profit status and critical steps in the transplantation process in Georgia, North Carolina, and South Carolina. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In this retrospective cohort study, we linked referral and evaluation data from all nine transplant centers in the Southeast with United States Renal Data System surveillance data. The cohort study included 33,651 patients with kidney failure initiating dialysis from January 1, 2012 to August 31, 2016. Patients were censored for event (date of referral, evaluation, or waitlisting), death, or end of study (August 31, 2017 for referral and March 1, 2018 for evaluation and waitlisting). The primary exposure was dialysis facility profit status: for profit versus nonprofit. The primary outcome was referral for evaluation at a transplant center after dialysis initiation. Secondary outcomes were start of evaluation at a transplant center after referral and waitlisting. RESULTS: Of the 33,651 patients with incident kidney failure, most received dialysis treatment at a for-profit facility (85%). For-profit (versus nonprofit) facilities had a lower cumulative incidence difference for referral within 1 year of dialysis (-4.5%; 95% confidence interval, -6.0% to -3.2%). In adjusted analyses, for-profit versus nonprofit facilities had lower referral (hazard ratio, 0.84; 95% confidence interval, 0.80 to 0.88). Start of evaluation within 6 months of referral (-1.0%; 95% confidence interval, -3.1% to 1.3%) and waitlisting within 6 months of evaluation (1.0%; 95% confidence interval, -1.2 to 3.3) did not meaningfully differ between groups. CONCLUSIONS: Findings suggest lower access to referral among patients dialyzing in for-profit facilities in the Southeast United States, but no difference in starting the evaluation and waitlisting by facility profit status.

Purification of Propylene and Ethylene by a Robust Metal-Organic Framework Mediated by Host-Guest Interactions.

Industrial purification of propylene and ethylene requires cryogenic distillation and selective hydrogenation over palladium catalysts to remove propane, ethane and/or trace amounts of acetylene. Here, we report the excellent separation of equimolar mixtures of propylene/propane and ethylene/ethane, and of a 1/100 mixture of acetylene/ethylene by a highly robust microporous material, MFM-520, under dynamic conditions. In situ synchrotron single crystal X-ray diffraction, inelastic neutron scattering and analysis of adsorption thermodynamic parameters reveal that a series of synergistic host-guest interactions involving hydrogen bonding and π⋅⋅⋅π stacking interactions underpin the cooperative binding of alkenes within the pore. Notably, the optimal pore geometry of the material enables selective accommodation of acetylene. The practical potential of this porous material has been demonstrated by fabricating mixed-matrix membranes comprising MFM-520, Matrimid and PIM-1, and these exhibit not only a high permeability for propylene (≈1984 Barrer), but also a separation factor of 7.8 for an equimolar mixture of propylene/propane at 298 K.

High Ammonia Adsorption in MFM-300 Materials: Dynamics and Charge Transfer in Host-Guest Binding.

Ammonia (NH3) is a promising energy resource owing to its high hydrogen density. However, its widespread application is restricted by the lack of efficient and corrosion-resistant storage materials. Here, we report high NH3 adsorption in a series of robust metal-organic framework (MOF) materials, MFM-300(M) (M = Fe, V, Cr, In). MFM-300(M) (M = Fe, VIII, Cr) show fully reversible capacity for >20 cycles, reaching capacities of 16.1, 15.6, and 14.0 mmol g-1, respectively, at 273 K and 1 bar. Under the same conditions, MFM-300(VIV) exhibits the highest uptake among this series of MOFs of 17.3 mmol g-1. In situ neutron powder diffraction, single-crystal X-ray diffraction, and electron paramagnetic resonance spectroscopy confirm that the redox-active V center enables host-guest charge transfer, with VIV being reduced to VIII and NH3 being oxidized to hydrazine (N2H4). A combination of in situ inelastic neutron scattering and DFT modeling has revealed the binding dynamics of adsorbed NH3 within these MOFs to afford a comprehensive insight into the application of MOF materials to the adsorption and conversion of NH3.

Kidney transplant program waitlisting rate as a metric to assess transplant access.

Kidney transplant program performance in the United States is commonly measured by posttransplant outcomes. Inclusion of pretransplant measures could provide a more comprehensive assessment of transplant program performance and necessary information for patient decision-making. In this study, we propose a new metric, the waitlisting rate, defined as the ratio of patients who are waitlisted in a center relative to the person-years referred for evaluation to a program. Furthermore, we standardize the waitlisting rate relative to the state average in Georgia, North Carolina, and South Carolina. The new metric was used as a proof-of-concept to assess transplant-program access compared to the existing transplant rate metric. The study cohorts were defined by linking 2017 United States Renal Data System (USRDS) data with transplant-program referral data from the Southeastern United States between January 1, 2012 and December 31, 2016. Waitlisting rate varied across the 9 Southeastern transplant programs, ranging from 10 to 22 events per 100 patient-years, whereas the program-specific waitlisting rate ratio ranged between 0.76 and 1.33. Program-specific waitlisting rate ratio was uncorrelated with the transplant rate ratio (r = -.15, 95% CI, -0.83 to 0.57). Findings warrant collection of national data on early transplant steps, such as referral, for a more comprehensive assessment of transplant program performance and pretransplant access.

Synthesis and molecular structure of perhalogenated rhenium-oxo corroles.

As part of our efforts to develop rhenium-oxo corroles as photosensitizers for oxygen sensing and photodynamic therapy, we investigated the potential ß-perhalogenation of five ReO meso-tris(para-X-phenyl)corroles, Re[TpXPC](O) (X = CF3, H, F, CH3, and OCH3), with elemental chlorine and bromine. With Cl2, ß-octachlorinated products Re[Cl8TpXPC](O) were rapidly obtained for X = CF3, H, and CH3, but X = OCH3 resulted in overchlorination on the meso-aryl groups. Full ß-octabromination proved slower relative to Cu and Ir corroles, but the desired Re[Br8TpXPC](O) products were finally obtained for X = H and F after a week at room temperature. For X = CH3 and OCH3, these conditions led to undecabrominated products Re[Br11TpXPC](O). Compared to the ß-unsubstituted starting materials, the ß-octahalogenated products were found to exhibit sharp 1H NMR signals at room temperature, indicating that the aryl groups are locked in place by the ß-halogens, and substantially redshifted Soret and Q bands. Single-crystal X-ray structures of Re[Cl8TpCF3PC](O), Re[Cl8TpCH3PC](O), and Re[Br8TpFPC](O) revealed mild saddling for one Cl8 structure and the Br8 structure. These structural variations, however, appear too insignificant to explain the slowness of the ß-octabromination protocols, which seems best attributed to the deactivating influence of the high-valent Re center.

Guest-Controlled Incommensurate Modulation in a Meta-Rigid Metal-Organic Framework Material.

Structural transitions of host systems in response to guest binding dominate many chemical processes. We report an unprecedented type of structural flexibility within a meta-rigid material, MFM-520, which exhibits a reversible periodic-to-aperiodic structural transition resulting from a drastic distortion of a [ZnO4N] node controlled by the specific host-guest interactions. The aperiodic crystal structure of MFM-520 has no three-dimensional (3D) lattice periodicity but shows translational symmetry in higher-dimensional (3 + 2)D space. We have directly visualized the aperiodic state which is induced by incommensurate modulation of the periodic framework of MFM-520·H2O upon dehydration to give MFM-520. Filling MFM-520 with CO2 and SO2 reveals that, while CO2 has a minimal structural influence, SO2 can further modulate the structure incommensurately. MFM-520 shows exceptional selectivity for SO2 under flue-gas desulfurization conditions, and the facile release of captured SO2 from MFM-520 enabled the conversion to valuable sulfonamide products. MFM-520 can thus be used as a highly efficient capture and delivery system for SO2.

Motor Unit Discharge Variability Is Increased in Mild-To-Moderate Parkinson's Disease.

Individuals with Parkinson's disease (PD) demonstrate deficits in muscle activation such as decreased amplitude and inappropriate bursting. There is evidence that some of these disturbances are more pronounced in extensor vs. flexor muscles. Surface EMG has been used widely to quantify muscle activation deficits in PD, but analysis of discharge of the underlying motor units may provide greater insight and be more sensitive to changes early in the disease. Of the few studies that have examined motor unit discharge in PD, the majority were conducted in the first dorsal interosseous, and no studies have measured motor units from extensor and flexor muscles within the same cohort. The objective of this study was to characterize the firing behavior of single motor units in the elbow flexor and extensor muscles during isometric contractions in people with mild-to-moderate PD. Ten individuals with PD (off-medication) and nine healthy controls were tested. Motor unit spike times were recorded via intramuscular EMG from the biceps and triceps brachii muscles during 30-s isometric contractions at 10% maximum voluntary elbow flexion and elbow extension torque, respectively. We selected variables of mean motor unit discharge rate, discharge variability, and torque variability to evaluate motor abnormalities in the PD group. The effects of group, muscle, and group-by-muscle on each variable were determined using separate linear mixed models. Discharge rate and torque variability were not different between groups, but discharge variability was significantly higher in the PD group for both muscles combined (p < 0.0001). We also evaluated the asymmetry in these motor variables between the triceps and biceps for each individual participant with PD to evaluate whether there was an association with disease severity. The difference in torque variability between elbow flexion and extension was significantly correlated with both the Hoehn and Yahr scale (rho = 0.71) and UPDRS (rho = 0.62). Our findings demonstrate that variability in motor output, rather than decreased discharge rates, may contribute to motor dysfunction in people with mild-to-moderate PD. Our findings provide insight into altered neural control of movement in PD and demonstrate the importance of measuring from multiple muscles within the same cohort.