Early-Onset Hypertension and Sex-Specific Residual Risk for Cardiovascular Disease in Type 2 Diabetes.

OBJECTIVE: To investigate whether the sex disparities in type 2 diabetes-associated cardiovascular disease (CVD) risks may be related to early-onset hypertension that could benefit from intensive blood pressure (BP) control. RESEARCH DESIGN AND METHODS: We analyzed intensive versus standard BP control in relation to incident CVD events in women and men with type 2 diabetes, based on their age of hypertension diagnosis. RESULTS: Among 3,792 adults with type 2 diabetes (49% women), multivariable-adjusted CVD risk was increased per decade earlier age at hypertension diagnosis (hazard ratio 1.11 [1.03-1.21], P = 0.006). Excess risk associated with early-diagnosed hypertension was attenuated in the presence of intensive versus standard antihypertensive therapy in women (P = 0.036) but not men (P = 0.76). CONCLUSIONS: Women with type 2 diabetes and early-onset hypertension may represent a higher-risk subpopulation that not only contributes to the female excess in diabetes-related CVD risk but may benefit from intensive BP control.

The book is just being written: The enduring journey of parents of children with emerging- ultrarare disorders.

Ultra rare disorders are being diagnosed at an unprecedented rate, due to genomic sequencing. These diagnoses are often a new gene association, for which little is known, and few share the diagnosis. For these diagnoses, we use the term emerging-ultrarare disorder (E-URD), defined as <100 diagnosed individuals. We contacted 20 parents of children diagnosed with an E-URD through the Duke University Research Sequencing Clinic. Seventeen completed semi-structured interviews exploring parental perspectives (7/17 had children in publications describing the phenotype; 4/17 had children in the first publication establishing a new disorder). Data were analyzed using a directed content approach informed by an empowerment framework. Parents reported a range of responses, including benefits of a diagnosis and challenges of facing the unknown, some described feeling lost and confused, while others expressed empowerment. Empowerment characteristics were hope for the future, positive emotions, engagement, and confidence/self-efficacy to connect with similar others, partner with healthcare providers, and seek new knowledge. We identified a subset of parents who proactively engaged researchers, supported research and publications, and created patient advocacy and support organizations to connect with and bolster similarly diagnosed families. Other parents reported challenges of low social support, low tolerance for uncertainty, limited knowledge about their child's disorder, as well as difficulty partnering with HCPs and connecting to an E-URD community. An overarching classification was developed to describe parental actions taken after an E-URD diagnosis: adjusting, managing, and pioneering. These classifications may help genetic counselors identify and facilitate positive steps with parents of a child with an E-URD.

Mono and biallelic variants in HCN2 cause severe neurodevelopmental disorders.

Hyperpolarization activated Cyclic Nucleotide (HCN) gated channels are crucial for various neurophysiological functions, including learning and sensory functions, and their dysfunction are responsible for brain disorders, such as epilepsy. To date, HCN2 variants have only been associated with mild epilepsy and recently, one monoallelic missense variant has been linked to developmental and epileptic encephalopathy. Here, we expand the phenotypic spectrum of HCN2- related disorders by describing twenty-one additional individuals from fifteen unrelated families carrying HCN2 variants. Seventeen individuals had developmental delay/intellectual disability (DD/ID), two had borderline DD/ID, and one had borderline DD. Ten individuals had epilepsy with DD/ID, with median age of onset of 10 months, and one had epilepsy with normal development. Molecular diagnosis identified thirteen different pathogenic HCN2 variants, including eleven missense variants affecting highly conserved amino acids, one frameshift variant, and one in-frame deletion. Seven variants were monoallelic of which five occurred de novo, one was not maternally inherited, one was inherited from a father with mild learning disabilities, and one was of unknown inheritance. The remaining six variants were biallelic, with four homozygous and two compound heterozygous variants. Functional studies using two-electrode voltage-clamp recordings in Xenopus laevis oocytes were performed on three monoallelic variants, p.(Arg324His), p.(Ala363Val), and p.(Met374Leu), and three biallelic variants, p.(Leu377His), p.(Pro493Leu) and p.(Gly587Asp). The p.(Arg324His) variant induced a strong increase of HCN2 conductance, while p.(Ala363Val) and p.(Met374Leu) displayed dominant negative effects, leading to a partial loss of HCN2 channel function. By confocal imaging, we found that the p.(Leu377His), p.(Pro493Leu) and p.(Gly587Asp) pathogenic variants impaired membrane trafficking, resulting in a complete loss of HCN2 elicited currents in Xenopus oocytes. Structural 3D-analysis in depolarized and hyperpolarized states of HCN2 channels, revealed that the pathogenic variants p.(His205Gln), p.(Ser409Leu), p.(Arg324Cys), p.(Asn369Ser) and p.(Gly460Asp) modify molecular interactions altering HCN2 function. Taken together, our data broadens the clinical spectrum associated with HCN2 variants, and disclose that HCN2 is involved in developmental encephalopathy with or without epilepsy.

Legislative Health Notes: Preliminary Learnings From Piloting a New Policy Analysis Tool.

CONTEXT: In 2018, the Health Impact Project (the Project) developed and tested a new health in all policies (HiAP) tool called "legislative health notes" to provide state and local legislators with peer-reviewed evidence, public health data, and local data that illustrate potential positive and negative health and equity effects of proposed bills. OBJECTIVES: The Project sought to refine the health note methodology while piloting the tool in the Colorado and Indiana General Assemblies, and with the Council of the District of Columbia, and worked with affiliates to introduce them in North Carolina, Ohio, and California. DESIGN AND PARTICIPANTS: External partners solicited feedback on health notes via semistructured interviews and surveys from legislators, legislative staff, and expert reviewers who were familiar with health notes in each of these jurisdictions. RESULTS: Respondents shared that health notes were nonpartisan, were easy for nonexperts to understand, and would be more effective if delivered earlier in the legislative process. CONCLUSION: In response to informant feedback, practitioners can explore adding high-level summaries, increasing focus on health equity implications and the potential to work with legislators during the policy formulation phase. Data from this pilot suggest that legislative health notes are a promising nonpartisan and standardized tool to better understand the health and equity implications of proposed legislation.

De novo GRIN variants in M3 helix associated with neurological disorders control channel gating of NMDA receptor.

N-methyl-D-aspartate receptors (NMDARs) are members of the glutamate receptor family and participate in excitatory postsynaptic transmission throughout the central nervous system. Genetic variants in GRIN genes encoding NMDAR subunits are associated with a spectrum of neurological disorders. The M3 transmembrane helices of the NMDAR couple directly to the agonist-binding domains and form a helical bundle crossing in the closed receptors that occludes the pore. The M3 functions as a transduction element whose conformational change couples ligand binding to opening of an ion conducting pore. In this study, we report the functional consequences of 48 de novo missense variants in GRIN1, GRIN2A, and GRIN2B that alter residues in the M3 transmembrane helix. These de novo variants were identified in children with neurological and neuropsychiatric disorders including epilepsy, developmental delay, intellectual disability, hypotonia and attention deficit hyperactivity disorder. All 48 variants in M3 for which comprehensive testing was completed produce a gain-of-function (28/48) compared to loss-of-function (9/48); 11 variants had an indeterminant phenotype. This supports the idea that a key structural feature of the M3 gate exists to stabilize the closed state so that agonist binding can drive channel opening. Given that most M3 variants enhance channel gating, we assessed the potency of FDA-approved NMDAR channel blockers on these variant receptors. These data provide new insight into the structure-function relationship of the NMDAR gate, and suggest that variants within the M3 transmembrane helix produce a gain-of-function.

Adaptation for sustainability in an implementation trial of team-based collaborative care.

Background: Sustaining healthcare interventions once they have been implemented is a pivotal public health endeavor. Achieving sustainability requires context-sensitive adaptations to evidence-based practices (EBPs) or the implementation strategies used to ensure their adoption. For replicability of adaptations beyond the specific setting in question, the underlying logic needs to be clearly described, and adaptations themselves need to be plainly documented. The goal of this project was to describe the process by which implementation facilitation was adapted to improve the uptake of clinical care practices that are consistent with the collaborative chronic care model (CCM). Method: Quantitative and qualitative data from a prior implementation trial found that CCM-consistent care practices were not fully sustained within outpatient general mental health teams that had received 1 year of implementation facilitation to support uptake. We undertook a multistep consensus process to identify adaptations to implementation facilitation based on these results, with the goal of enhancing the sustainability of CCM-based care in a subsequent trial. The logic for these adaptations, and the resulting adaptations themselves, were documented using two adaptation-oriented implementation frameworks (the iterative decision-making for evaluation of adaptations [IDEA] and the framework for reporting adaptations and modifications to evidence-based implementation strategies [FRAME-IS], respectively). Results: Three adaptations emerged from this process and were documented using the FRAME-IS: (a) increasing the scope of implementation facilitation within the medical center, (b) having the internal facilitator take a greater role in the implementation process, and (c) shortening the implementation timeframe from 12 to 8 months, while increasing the intensity of facilitation support during that time. Conclusions: EBP sustainability may require careful adaptation of EBPs or the implementation strategies used to get them into routine practice. Recently developed frameworks such as the IDEA and FRAME-IS may be used to guide decision-making and document resulting adaptations themselves. An ongoing funded study is investigating the utility of the resulting adaptations for improving healthcare.

Evidence-based treatments may not be sustained after they have been implemented in healthcare settings. To address this, treatments and implementation strategies may need to be adapted to fit the local context or the patient population. Maximizing the usefulness of such adaptations requires documenting the decision-making process. Understanding how an implementation strategy has been adapted for a given study or setting is crucial to ensuring that adaptations don't compromise fidelity to the implementation strategy while enabling its replicability in similar settings. This article uses two adaptation frameworks to describe the process by which implementation facilitation, a common implementation strategy, was adapted to help establish and sustain effective mental health clinical teams in VA medical centers. It is our hope that our description of this process may help healthcare researchers, administrators, and policymakers to describe and document adaptations to implementation strategies in their own settings.

Sustaining the collaborative chronic care model in outpatient mental health: a matrixed multiple case study.

BACKGROUND: Sustaining evidence-based practices (EBPs) is crucial to ensuring care quality and addressing health disparities. Approaches to identifying factors related to sustainability are critically needed. One such approach is Matrixed Multiple Case Study (MMCS), which identifies factors and their combinations that influence implementation. We applied MMCS to identify factors related to the sustainability of the evidence-based Collaborative Chronic Care Model (CCM) at nine Department of Veterans Affairs (VA) outpatient mental health clinics, 3-4 years after implementation support had concluded. METHODS: We conducted a directed content analysis of 30 provider interviews, using 6 CCM elements and 4 Integrated Promoting Action on Research Implementation in Health Services (i-PARIHS) domains as codes. Based on CCM code summaries, we designated each site as high/medium/low sustainability. We used i-PARIHS code summaries to identify relevant factors for each site, the extent of their presence, and the type of influence they had on sustainability (enabling/neutral/hindering/unclear). We organized these data into a sortable matrix and assessed sustainability-related cross-site trends. RESULTS: CCM sustainability status was distributed among the sites, with three sites each being high, medium, and low. Twenty-five factors were identified from the i-PARIHS code summaries, of which 3 exhibited strong trends by sustainability status (relevant i-PARIHS domain in square brackets): "Collaborativeness/Teamwork [Recipients]," "Staff/Leadership turnover [Recipients]," and "Having a consistent/strong internal facilitator [Facilitation]" during and after active implementation. At most high-sustainability sites only, (i) "Having a knowledgeable/helpful external facilitator [Facilitation]" was variably present and enabled sustainability when present, while (ii) "Clarity about what CCM comprises [Innovation]," "Interdisciplinary coordination [Recipients]," and "Adequate clinic space for CCM team members [Context]" were somewhat or less present with mixed influences on sustainability. CONCLUSIONS: MMCS revealed that CCM sustainability in VA outpatient mental health clinics may be related most strongly to provider collaboration, knowledge retention during staff/leadership transitions, and availability of skilled internal facilitators. These findings have informed a subsequent CCM implementation trial that prospectively examines whether enhancing the above-mentioned factors within implementation facilitation improves sustainability. MMCS is a systematic approach to multi-site examination that can be used to investigate sustainability-related factors applicable to other EBPs and across multiple contexts.

A randomized, double-blind study of zinpentraxin alfa in patients with myelofibrosis who were previously treated with or ineligible for ruxolitinib: Stage 2 of a phase II trial.

Not available.

Overcoming barriers to implementation: mapping implementation strategies in four hospital in home programs within the Veterans Health Administration.

The Hospital at Home model, called Hospital-in-Home (HIH) in the Department of Veterans Affairs, delivers coordinated, high-value care aligned with older adult and caregiver preferences. Documenting implementation barriers and corresponding strategies to overcome them can address challenges to widespread adoption. To evaluate HIH implementation barriers and identify strategies to address them, we conducted interviews with 8 HIH staff at 4 hospitals between 2010 and 2013. We utilized qualitative directed content analysis guided by the Consolidated Framework for Implementation Research (CFIR) and mapped identified barriers to possible strategies using the CFIR-Expert Recommendations for Implementing Change (ERIC) Matching Tool. We identified 11 barriers spanning 5 CFIR domains. Three implementation strategies - identifying and preparing champions, conducting educational meetings, and capturing and sharing local knowledge - achieved high expert endorsement for each barrier. A mix of strategies targeting resources, organizational readiness and fit, and leadership engagement should be considered to support the sustainability and spread of HIH.

Quality Improvement Efforts in VA Community Living Centers Following Public Reporting of Performance.

For two decades, the U.S. government has publicly reported performance measures for most nursing homes, spurring some improvements in quality. Public reporting is new, however, to Department of Veterans Affairs nursing homes (Community Living Centers [CLCs]). As part of a large, public integrated healthcare system, CLCs operate with unique financial and market incentives. Thus, their responses to public reporting may differ from private sector nursing homes. In three CLCs with varied public ratings, we used an exploratory, qualitative case study approach involving semi-structured interviews to compare how CLC leaders (n = 12) perceived public reporting and its influence on quality improvement. Across CLCs, respondents said public reporting was helpful for transparency and to provide an "outside perspective" on CLC performance. Respondents described employing similar strategies to improve their public ratings: using data, engaging staff, and clearly defining staff roles vis-à-vis quality improvement, although more effort was required to implement change in lower performing CLCs. Our findings augment those from prior studies and offer new insights into the potential for public reporting to spur quality improvement in public nursing homes and those that are part of integrated healthcare systems.

Implementation Lessons Learned: Distress Behaviors in Dementia Intervention in Veterans Health Administration.

BACKGROUND AND OBJECTIVES: Evidence-based practices to manage distress behaviors in dementia (DBD) are not consistently implemented despite demonstrated effectiveness. The Veterans Health Administration (VA) trained teams to implement Staff Training in Assisted Living Residences (STAR)-VA, an intervention to manage DBD in VA nursing home settings, or Community Living Centers (CLCs). This paper summarizes multiyear formative evaluation results including challenges, adaptations, and lessons learned to support sustained integration into usual care across CLCs nationwide. RESEARCH DESIGN AND METHODS: STAR was selected as an evidence-based practice for DBD, adapted for and piloted in VA (STAR-VA), and implemented through a train-the-trainer program from 2013 to 2018. Training and consultation were provided to 92 CLC teams. Evaluation before and after training and consultation included descriptive statistics of measures of clinical impact and survey feedback from site teams regarding self-confidence, engagement, resource quality, and content analysis of implementation facilitators and challenges. RESULTS: STAR-VA training and consultation increased staff confidence and resulted in significant decreases in DBD, depression, anxiety, and agitation for Veterans engaged in the intervention. Implementation outcomes demonstrated feasibility and identified facilitators and barriers. Key findings were interpreted using implementation frameworks and informed subsequent modifications to sustain implementation. DISCUSSION AND IMPLICATIONS: STAR-VA successfully prepared teams to manage DBD and resulted in improved outcomes. Lessons learned include importance of behavioral health-nursing partnerships, continuous engagement, iterative feedback and adaptations, and sustainment planning. Evaluation of sustainment factors has informed selection of implementation strategies to address sustainment barriers. Lessons learned have implications for integrating team-based practices into system-level practice.

Home alone or connected: Caregiver communication and training from health providers.

BACKGROUND: As care shifts from institutional to community settings, family caregivers are providing increasing support to older adults, including complex medical/nursing care. In the mid-late pandemic, technology advancements such as use of online patient portals present opportunities for communication and care delivery. This study aims to assess the association between caregiver medical/nursing tasks or patient portal use with contact, communication, and training of caregivers by healthcare providers. METHODS: We conducted a cross-sectional analysis of caregiver data from the 2021 National Study of Caregiving (NSOC), linked to the National Health and Aging Trends Study (NHATS). NHATS is nationally-representative, annual survey of Medicare enrollees; NSOC surveys family/unpaid caregivers of NHATS participants. Logistic regression tested association between whether the caregiver does medical/nursing tasks or uses an online patient portal to contact the medical team (independent variables), and communication with or training by the medical team (dependent variables). RESULTS: Participants were 1590 caregivers of living, community-dwelling older adults. More than half (54%) reported no contact with the care recipient's medical team in the past year. Caregivers who did medical/nursing tasks (OR = 3.10; 95% CI: 2.16, 4.46) or who used patient portals (OR = 3.28; 95% CI: 1.96, 5.51) had higher odds of contacting the older adult's medical team. Thirty percent of caregivers stated communication was either not at all or just a little helpful. Sixty-seven percent reported that providers rarely asked if they needed help managing the older adult's treatments. Just 6% of caregivers reported receiving any caregiver training in the last year. CONCLUSIONS: Both medical/nursing tasks and online patient portal use were independently associated with contact with health providers. Overall contact, communication, and training were limited or of variable value. Despite recent policy changes and technology advancement, there is still a need for improved integration of caregivers into health teams with ongoing assessment of their needs.

Factors Related to Higher and Lower Performance and Adherence in STAR-VA Program Sustainment in Department of Veterans Affairs (VA) Community Living Centers (CLCs).

OBJECTIVES: We identify factors associated with sustainment of an intervention (STAR-VA) to address distress behaviors in dementia (DBD), guided by the Organizational Memory Knowledge Reservoir (KR) framework, compared across 2 types of outcomes: (1) site performance improvement on a clinical outcome, the magnitude of change in levels of DBD, and (2) self-rated adherence to STAR-VA core components, a process outcome. DESIGN: We used a cross-sectional sequential explanatory mixed methods design guided by the Organizational Memory Framework. SETTING AND PARTICIPANTS: We selected 20 of 79 sites that completed STAR-VA training and consultation based on rankings on 2 outcomes-change in an indicator of DBD and reported adherence to STAR-VA core components. We recruited key informants most knowledgeable about STAR-VA resulting in a sample of 43% behavioral coordinators, 36% nurse champions, and 21% nurse leaders. METHODS: We collected data with key informants at each Community Living Center (CLC) from December 2018 to June 2019. We analyzed data using within-case and cross-case matrixes created from the coded transcripts for each a priori KR domain. We then assessed if there were any similarities or differences for CLCs in comparable DBD performance and STAR-VA adherence categories. RESULTS: We found 4 KRs that differentiated sustainment factors based on CLC implementation process and clinical outcomes-3 KRs related to DBD performance (people, relationships, and routines) and 2 related to STAR-VA adherence (relationships and culture). CONCLUSIONS AND IMPLICATIONS: This evaluation found several knowledge retention mechanisms that differ in high and low performance/adherence sites. Our findings highlight knowledge retention/sustainment strategies based on site functioning to support sustainment strategies in the CLC. Understanding sustainment factors as they relate to clinical and process outcomes is innovative and can be used to support CLCs struggling with sustainment. More research is needed to inform tailored sustainment efforts based on site functioning in the nursing home setting.

The best of both worlds: Blending cutting-edge research with clinical processes for a productive exome clinic.

Genomic medicine has been transformed by next-generation sequencing (NGS), inclusive of exome sequencing (ES) and genome sequencing (GS). Currently, ES is offered widely in clinical settings, with a less prevalent alternative model consisting of hybrid programs that incorporate research ES along with clinical patient workflows. We were among the earliest to implement a hybrid ES clinic, have provided diagnoses to 45% of probands, and have identified several novel candidate genes. Our program is enabled by a cost-effective investment by the health system and is unique in encompassing all the processes that have been variably included in other hybrid/clinical programs. These include careful patient selection, utilization of a phenotype-agnostic bioinformatics pipeline followed by manual curation of variants and phenotype integration by clinicians, close collaborations between the clinicians and the bioinformatician, pursuit of interesting variants, communication of results to patients in categories that are predicated upon the certainty of a diagnosis, and tracking changes in results over time and the underlying mechanisms for such changes. Due to its effectiveness, scalability to GS and its resource efficiency, specific elements of our paradigm can be incorporated into existing clinical settings, or the entire hybrid model can be implemented within health systems that have genomic medicine programs, to provide NGS in a scientifically rigorous, yet pragmatic setting.

Sustained activation of 12/15 lipoxygenase (12/15 LOX) contributes to impaired renal recovery post ischemic injury in male SHR compared to females.

BACKGROUND: Acute kidney injury (AKI) due to ischemia-reperfusion (IR) is a serious and frequent complication in clinical settings, and mortality rates remain high. There are well established sex differences in renal IR, with males exhibiting greater injury following an ischemic insult compared to females. We recently reported that males have impaired renal recovery from ischemic injury vs. females. However, the mechanisms mediating sex differences in renal recovery from IR injury remain poorly understood. Elevated 12/15 lipoxygenase (LOX) activity has been reported to contribute to the progression of numerous kidney diseases. The goal of the current study was to test the hypothesis that enhanced activation of 12/15 LOX contributes to impaired recovery post-IR in males vs. females. METHODS: 13-week-old male and female spontaneously hypertensive rats (SHR) were randomized to sham or 30-minute warm bilateral IR surgery. Additional male and female SHR were randomized to treatment with vehicle or the specific 12/15 LOX inhibitor ML355 1 h prior to sham/IR surgery, and every other day following up to 7-days post-IR. Blood was collected from all rats 1-and 7-days post-IR. Kidneys were harvested 7-days post-IR and processed for biochemical, histological, and Western blot analysis. 12/15 LOX metabolites 12 and 15 HETE were measured in kidney samples by liquid chromatography-mass spectrometry (LC/MS). RESULTS: Male SHR exhibited delayed recovery of renal function post-IR vs. male sham and female IR rats. Delayed recovery in males was associated with activation of renal 12/15 LOX, increased renal 12-HETE, enhanced endoplasmic reticulum (ER) stress, lipid peroxidation, renal cell death and inflammation compared to females 7-days post-IR. Treatment of male SHR with ML355 lowered levels of 12-HETE and resulted in reduced renal lipid peroxidation, ER stress, tubular cell death and inflammation 7-days post-IR with enhanced recovery of renal function compared to vehicle-treated IR male rats. ML355 treatment did not alter IR-induced increases in plasma creatinine in females, however, tubular injury and cell death were attenuated in ML355 treated females compared to vehicle-treated rats 7 days post-IR. CONCLUSION: Our data demonstrate that sustained activation 12/15 LOX contributes to impaired renal recovery post ischemic injury in male and female SHR, although males are more susceptible on this mechanism than females.

Single-cell multi-omics identifies chronic inflammation as a driver of TP53-mutant leukemic evolution.

Understanding the genetic and nongenetic determinants of tumor protein 53 (TP53)-mutation-driven clonal evolution and subsequent transformation is a crucial step toward the design of rational therapeutic strategies. Here we carry out allelic resolution single-cell multi-omic analysis of hematopoietic stem/progenitor cells (HSPCs) from patients with a myeloproliferative neoplasm who transform to TP53-mutant secondary acute myeloid leukemia (sAML). All patients showed dominant TP53 'multihit' HSPC clones at transformation, with a leukemia stem cell transcriptional signature strongly predictive of adverse outcomes in independent cohorts, across both TP53-mutant and wild-type (WT) AML. Through analysis of serial samples, antecedent TP53-heterozygous clones and in vivo perturbations, we demonstrate a hitherto unrecognized effect of chronic inflammation, which suppressed TP53 WT HSPCs while enhancing the fitness advantage of TP53-mutant cells and promoted genetic evolution. Our findings will facilitate the development of risk-stratification, early detection and treatment strategies for TP53-mutant leukemia, and are of broad relevance to other cancer types.

Extravasation of Blood and Blood Toxicity Drives Tubular Injury from RBC Trapping in Ischemic AKI.

Red blood cell (RBC) trapping is common in ischemic acute kidney injury (AKI) and presents as densely packed RBCs that accumulate within and engorge the kidney medullary circulation. In this study, we tested the hypothesis that "RBC trapping directly promotes tubular injury independent of extending ischemia time." Studies were performed on rats. Red blood cell congestion and tubular injury were compared between renal arterial clamping, venous clamping, and venous clamping of blood-free kidneys. Vessels were occluded for either 15 or 45 min with and without reperfusion. We found that RBC trapping in the medullary capillaries occurred rapidly following reperfusion from renal arterial clamping and that this was associated with extravasation of blood from congested vessels, uptake of blood proteins by the tubules, and marked tubular injury. To determine if this injury was due to blood toxicity or an extension of ischemia time, we compared renal venous and arterial clamping without reperfusion. Venous clamping resulted in RBC trapping and marked tubular injury within 45 min of ischemia. Conversely, despite the same ischemia time, RBC trapping and tubular injury were minimal following arterial clamping without reperfusion. Confirming the role of blood toward tubular injury, injury was markedly reduced in blood-free kidneys with venous clamping. Our data demonstrate that RBC trapping results in the rapid extravasation and uptake of blood components by tubular cells, causing toxic tubular injury. Tubular toxicity from extravasation of blood following RBC trapping appears to be a major component of tubular injury in ischemic AKI, which has not previously been recognized.