Application of constructivism and cognitive flexibility theory to build a Comprehensive, Integrated, Multimodal Interprofessional Education and Practice (CIM-IPEP) program.

Interprofessional Education (IPE) is challenging to implement and assess due to barriers preventing interprofessional communication, inadequately defined accreditation criteria, ambiguous professional roles and responsibilities, and the inherently "ill-structured" educational construct of IPE. To address these gaps, a novel comprehensive, integrated, and multimodal interprofessional education and practice (CIM-IPEP) curriculum involving students from pharmacy, medicine, psychology, and nursing professional degree programmes was created. CIM-IPEP was carefully designed based on cognitive flexibility theory (CFT) to reinforce the complexities associated with teaching and learning for multi-faceted and dynamic domains such as IPE. CFT emphasises pluralistic representation, repetition, and cognitive layering in experiential learning for ill-structured domains. Thus, CIM-IPEP was vertically and horizontally aligned within individual colleges and included diverse IPE experiences in required courses such as Foundations of IPE, and high-fidelity simulation events, culminating in an IPE-Hotspotting elective, which exposed learners to real-world patient cases. Cases were presented in a format of increasing complexity emphasising the integration of foundational and skills-based learning using constructivist methods such as Team-Based and Case-Based Learning. CIM-IPEP offers a novel IPE model. Here we present a stepwise development and implementation blueprint for similar IPE programmes that is readily transferable to other health profession education (HPE) programmes.

The roles of medical examiners in the COVID-19 era: a comparison between the United States and Italy.

Italy and the United States are two of the countries most affected by SARS-CoV-2 (COVID-19), with more than 240,760 confirmed cases in Italy and 2,699,658 in the United States (as of July 2, 2020). The current COVID-19 pandemic has led to substantial changes in many fields of medicine, specifically in the forensic discipline. Medicolegal activities related to conducting autopsies have been largely affected by the COVID-19 pandemic. Postmortem examinations are generally discouraged by government regulations due to the risk of spreading the disease further through the handling and dissection of bodies from patients who succumbed to COVID-19 infection. There is a paucity of data regarding the persistence of SARS-CoV-2 in bodies, as well as concerning the reliability of swabbing methods in human remains. On the other hand, the autopsy is an essential tool to provide necessary information about the pathophysiology of the disease that presents useful clinical and epidemiological insights. On this basis, we aim to address issues concerning general medical examiner/coroner organization, comparing the Italian and American systems. We also discuss the pivotal roles of forensic pathologists in informing infectious disease surveillance. Finally, we focus on the impact of COVID-19 emergency on medicolegal practices in Italy and the United States, as well as the responses of the forensic scientific community to the emerging concerns related to the pandemic. We believe that stronger efforts by authorities are necessary to facilitate completing postmortem examinations, as data derived from such assessments are expected to be paramount to improving patient management and disease prevention.

Impact of high-stakes exams, incentives, and preparation on student performance: Insights from the pharmacy curriculum outcomes assessment.

INTRODUCTION: Efforts to ensure success of pharmacy students in passing pharmacy standardized exams require substantial investments. Engaging students effectively can be a challenge when there are no consequences for non-participation or poor performance. This study examined how engagement reinforcement, including high-stake exam requirements, instructional strategies, and incentives, impacted student performance on the Pharmacy Curriculum Outcomes Assessment (PCOA). METHODS: PCOA scores, milestone exams, grade point averages (GPAs), and PCOA preparedness assessments for cohorts (Co) that received high-stakes exams, incentives, and preparation (Co2019, Co2020, and Co2021) was compared with those that did not receive these interventions (Co2017 and Co2018). Students' perceptions regarding reinforcement, incentive, and preparedness were evaluated using an anonymous survey. RESULTS: Analyzing data from 545 students over five years, mandated PCOA preparedness, high-stakes PCOA requirements, and incentives for Co2019, Co2020, and Co2021 improved scores by 11% to 18% compared to Co2017 and Co2018. This corresponded to a rise in performance from the 12th to 27th percentile for Co2017 and Co2018 to the 39th to 49th percentile for Co2019, Co2020, and Co2021. In these later cohorts, PCOA scores consistently correlated with the school's milestone exams and students' cumulative GPAs (correlation coefficients 0.47-0.70, P < .001), while no such correlation was observed in Co2017 and Co2018. Faculty-led PCOA preparation yielded better results (48.2% in Co2020, 45.8% in Co2021) than self-learning (42% in Co2019). Students using faculty-prepared assessments reported increased confidence in biomedical and pharmaceutical sciences. CONCLUSIONS: This study highlights the importance of high-stakes requirements, incentives, and thorough preparation in improving PCOA results.

Report of the 2023 AACP Council of Deans Taskforce on Pharmacy Research and Scholarship.

OBJECTIVE: The objective of this review is to provide the conclusions from the American Association of Colleges of Pharmacy (AACP) Council of Deans (COD) Taskforce on Research and Scholarship. FINDINGS: The charges and the findings of the committee are: (1) Define the scholarship needs/opportunities to strengthen the outputs. The committee recommends that AACP update its definitions of research/scholarship to include discovery, integration, application/practice, and teaching/learning. A deployed survey demonstrated a high Special Interest Groups research/scholarship interest. (2) Assemble a toolkit of grant and scholarship resources to assist colleges/schools. The AACP should update the existing funding opportunity listing and combine it with additional resources. (3) Create a framework for effective research collaboration and mentorship. The AACP should identify key areas of pharmacy research and experts to serve as mentors and to meet with external stakeholders. (4) and (5) Consider the need for and purpose of a COD standing committee for research and scholarship. Explore the value of a formal research dean's subcommittee. It was recommended that AACP form a research/scholarship committee or Special Interest Groups and create the Pharmacy Scholarship, Research, and Graduate Education pre-meeting to the Interim Meeting. (6) Identify key statements/outputs of the COD that need to be prepared for publication/sharing. We recommended the key statement/outputs in the areas of discovery, integration, application/practice, and teaching and learning. SUMMARY: The taskforce reviewed the state of research and scholarship across the Academy and provided recommendations with the goal of advancing research across all areas of the pharmacy profession.

A Resource Compendium for Embedding LGBTQIA+ Patient Care in the Professional Identity of Community Pharmacists.

OBJECTIVES: Cultural, clinical, social, and legally competent patient care for lesbian, gay, bisexual, transgender, queer, intersex, and asexual (LGBTQIA+) patients is currently scarcely incorporated in pharmacy curricula. Furthermore, clinical, legal, and socio-cultural training that prepares pharmacists on the job to provide LGBTQIA+ competent patient care is scant. Here, our objectives were to (1) systematically review the literature using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify trends in community pharmacists' professional identity development related to the provision of competent LGBTQIA+ patient care, and (2) create a reference guide for community pharmacists for self-directed learning. The literature search focused on 4 professional identity domains common to most pharmacists: academic and clinical competence, cultural sensitivity, knowledge of state and federal laws, and continuing professional development. FINDINGS: A total of 207 articles were identified, with 93 retrieved, of which 26 articles were included in the final analysis based on title and abstract and other inclusion criteria. SUMMARY: Overall, our search identified that the LGBTQIA+ health professions literature focused on the following themes: guidance for appropriate drug selection and therapy, creation of cultural sensitivity training curricula, community pharmacists' perceptions of their ability to provide LGBTQIA+ care, health system interventions, and Allyship education for advancing LGBTQIA+ care, the need for enhanced training of pharmacists for understanding the federal and state laws and requirements while providing care, and the need for a resource compendium to help community pharmacists access self-directed learning information, for which we have created a self-help resource guide for pharmacists in these 4 professional pharmacist identity domains.

The Race for COVID-19 Vaccines: The Various Types and Their Strengths and Weaknesses.

SARS-CoV-2 causes the highly contagious coronavirus disease (COVID-19), first discovered in Wuhan, China, in December of 2019. As of August 21, 2021, over 211 million people have been diagnosed with COVID-19 and 4.42 million people have died from the disease worldwide. The COVID-19 pandemic has adversely affected world economies, global public health infrastructure, and social behaviors. Despite physical distancing and the advent of symptomatic and monoclonal antibody therapies, perhaps the most effective method to combat COVID-19 remains the creation of immunity through vaccines. Scientific communities globally have been diligently working to develop vaccines since the start of the pandemic. Though a few have been authorized for use, the Pfizer vaccine was the first to be given full approval in the United States in August 2021 - being the quickest vaccine to ever be developed. Although several vaccines produced via different approaches are in use, no mortality has been reported thus far from vaccine use. Here, we highlight the latest advances in the development of the COVID-19 vaccines, specifically the lead candidates that are in late-stage clinical trials or authorized for emergency use. As SARS-CoV-2 uses its spike protein to enter a host cell and cause infection, most vaccine candidates target this protein. This review describes the various COVID-19 vaccines - authorized and/or under development - and their composition, advantages, and potential limitations as the world continues to fight this devastating pandemic.

A Critical Appraisal of Educational Theory to Examine HBCU and Black Students' Professional Identity Formation.

OBJECTIVES: This article explores educational theories and existing literature that describe the impact of Historically Black College or University (HBCU) educational environments on Black students' personal and professional development. Literature on professional identity formation (PIF) in pharmacy education is also examined to describe the influence of HBCU pharmacy education on Black pharmacy students' PIF. FINDINGS: Tinto's theory of student retention, Arroyo and Gasman's HBCU educational framework, and Bank's theory of multicultural education are described, as key elements of HBCU education that foster PIF in minoritized student populations. Each of the 3 models addresses professional identity traits associated with pharmacists and pharmacy students, and this review examines the role of HBCU education in Black Doctor of Pharmacy students' development of academic competence, leadership, professional communication, and advocacy. SUMMARY: Existing educational frameworks and models of student retention can be applied to promote student growth, psychological safety, and feelings of belonging in minoritized student populations. By engaging these models, pharmacy training environments can support Black students and other minoritized student populations as they develop their own professional identities in the pursuit of fulfilling careers.

A First Report of HCTZ and Dicyclomine Induced Uncharacteristic Contraction Alkalosis.

Background: Contraction alkalosis is characterized by low serum sodium and chloride and high serum carbon dioxide and bicarbonate levels. Case Report: A 28-year-old Caucasian active-duty male with a history of autosomal dominant polycystic kidney disease and diarrhea-predominant Irritable Bowel Syndrome (D-IBS) presented to his primary care provider (PCP) with elevated blood pressure (136/96 mmHg), was diagnosed with stage-2 hypertension, and started oral HCTZ (25 mg/day). His medications included dicyclomine (10 mg oral three times daily). Subsequently, (Visit 1), his blood pressure was 130/91 mmHg and he was started on telmisartan (20 mg/day). At Visit 2, 4 weeks later, his blood pressure improved (121/73 mmHg); however, blood chemistry revealed elevated serum CO2 (32 mEq/L) and chloride (94 mmol/L). Four days later, the patient presented to the Emergency Department with dyspnea and swallowing difficulty. The patient returned to his PCP 3 days later complaining of cough, congestion, vomiting, and mild dyspnea, blood pressure of 124/84 mmHg. Two months later, sudden onset of projectile vomiting and abdominal pain while running was reported, resolved by rehydration and a single oral dose of prochlorperazine 25 mg. Three months later, (Visit 3), he complained of lightheadedness and cloudy judgment, suggesting contraction alkalosis. HCTZ was discontinued and telmisartan was increased to 20 mg twice daily. A follow-up blood chemistry panel 2 weeks later revealed serum chloride and CO2 levels within normal limits and blood pressure under 130/80 mmHg. Conclusion: This is the first known report of contraction alkalosis driven by drug-drug interaction between dicyclomine and HCTZ.

Dendritic cells promote pancreatic viability in mice with acute pancreatitis.

BACKGROUND & AIMS: The cellular mediators of acute pancreatitis are incompletely understood. Dendritic cells (DCs) can promote or suppress inflammation, depending on their subtype and context. We investigated the roles of DC in development of acute pancreatitis. METHODS: Acute pancreatitis was induced in CD11c.DTR mice using caerulein or L-arginine; DCs were depleted by administration of diphtheria toxin. Survival was analyzed using Kaplan-Meier method. RESULTS: Numbers of major histocompatibility complex II(+)CD11c(+) DCs increased 100-fold in pancreata of mice with acute pancreatitis to account for nearly 15% of intrapancreatic leukocytes. Intrapancreatic DCs acquired a distinct immune phenotype in mice with acute pancreatitis; they expressed higher levels of major histocompatibility complex II and CD86 and increased production of interleukin-6, membrane cofactor protein-1, and tumor necrosis factor-α. However, rather than inducing an organ-destructive inflammatory process, DCs were required for pancreatic viability; the exocrine pancreas died in mice that were depleted of DCs and challenged with caerulein or L-arginine. All mice with pancreatitis that were depleted of DCs died from acinar cell death within 4 days. Depletion of DCs from mice with pancreatitis resulted in neutrophil infiltration and increased levels of systemic markers of inflammation. However, the organ necrosis associated with depletion of DCs did not require infiltrating neutrophils, activation of nuclear factor-κB, or signaling by mitogen-activated protein kinase or tumor necrosis factor-α. CONCLUSIONS: DCs are required for pancreatic viability in mice with acute pancreatitis and might protect organs against cell stress.

Dendritic cell depletion exacerbates acetaminophen hepatotoxicity.

UNLABELLED: Acetaminophen (APAP) overdose is one of the most frequent causes of acute liver failure in the United States and is primarily mediated by toxic metabolites that accumulate in the liver upon depletion of glutathione stores. However, cells of the innate immune system, including natural killer (NK) cells, neutrophils, and Kupffer cells, have also been implicated in the centrilobular liver necrosis associated with APAP. We have recently shown that dendritic cells (DCs) regulate intrahepatic inflammation in chronic liver disease and, therefore, postulated that DC may also modulate the hepatotoxic effects of APAP. We found that DC immune-phenotype was markedly altered after APAP challenge. In particular, liver DC expressed higher MHC II, costimulatory molecules, and Toll-like receptors, and produced higher interleukin (IL)-6, macrophage chemoattractant protein-1 (MCP-1), and tumor necrosis factor alpha (TNF-α). Conversely, spleen DC were unaltered. However, APAP-induced centrilobular necrosis, and its associated mortality, was markedly exacerbated upon DC depletion. Conversely, endogenous DC expansion using FMS-like tyrosine kinase 3 ligand (Flt3L) protected mice from APAP injury. Our mechanistic studies showed that APAP liver DC had the particular capacity to prevent NK cell activation and induced neutrophil apoptosis. Nevertheless, the exacerbated hepatic injury in DC-depleted mice challenged with APAP was independent of NK cells and neutrophils or numerous immune modulatory cytokines and chemokines. CONCLUSION: Taken together, these data indicate that liver DC protect against APAP toxicity, whereas their depletion is associated with exacerbated hepatotoxicity.

In hepatic fibrosis, liver sinusoidal endothelial cells acquire enhanced immunogenicity.

The normal liver is characterized by immunologic tolerance. Primary mediators of hepatic immune tolerance are liver sinusoidal endothelial cells (LSECs). LSECs block adaptive immunogenic responses to Ag and induce the generation of T regulatory cells. Hepatic fibrosis is characterized by both intense intrahepatic inflammation and altered hepatic immunity. We postulated that, in liver fibrosis, a reversal of LSEC function from tolerogenic to proinflammatory and immunogenic may contribute to both the heightened inflammatory milieu and altered intrahepatic immunity. We found that, after fibrotic liver injury from hepatotoxins, LSECs become highly proinflammatory and secrete an array of cytokines and chemokines. In addition, LSECs gain enhanced capacity to capture Ag and induce T cell proliferation. Similarly, unlike LSECs in normal livers, in fibrosis, LSECs do not veto dendritic cell priming of T cells. Furthermore, whereas in normal livers, LSECs are active in the generation of T regulatory cells, in hepatic fibrosis LSECs induce an immunogenic T cell phenotype capable of enhancing endogenous CTLs and generating potent de novo CTL responses. Moreover, depletion of LSECs from fibrotic liver cultures mitigates the proinflammatory milieu characteristic of hepatic fibrosis. Our findings offer a critical understanding of the role of LSECs in modulating intrahepatic immunity and inflammation in fibro-inflammatory liver disease.

Role of calcium-independent phospholipase A2 in the pathogenesis of Barth syndrome.

Quantitative and qualitative alterations of mitochondrial cardiolipin have been implicated in the pathogenesis of Barth syndrome, an X-linked cardioskeletal myopathy caused by a deficiency in tafazzin, an enzyme in the cardiolipin remodeling pathway. We have generated and previously reported a tafazzin-deficient Drosophila model of Barth syndrome that is characterized by low cardiolipin concentration, abnormal cardiolipin fatty acyl composition, abnormal mitochondria, and poor motor function. Here, we first show that tafazzin deficiency in Drosophila disrupts the final stage of spermatogenesis, spermatid individualization, and causes male sterility. This phenotype can be genetically suppressed by inactivation of the gene encoding a calcium-independent phospholipase A(2), iPLA2-VIA, which also prevents cardiolipin depletion/monolysocardiolipin accumulation, although in wild-type flies inactivation of the iPLA2-VIA does not affect the molecular composition of cardiolipin. Furthermore, we show that treatment of Barth syndrome patients' lymphoblasts in tissue culture with the iPLA(2) inhibitor, bromoenol lactone, partially restores their cardiolipin homeostasis. Taken together, these findings establish a causal role of cardiolipin deficiency in the pathogenesis of Barth syndrome and identify iPLA2-VIA as an important enzyme in cardiolipin deacylation, and as a potential target for therapeutic intervention.

Impact of a Prepharmacy Program on Students' Self-Awareness of Pharmacist Professional Identity: Comparison between Virtual and In-Person Settings.

Ensuring an adequate preparation for undergraduate students transitioning to pharmacy school is challenging. A significant barrier is changing from a subordinate to a critical thinking mindset while self-identifying as a professional. Here, we aimed to (1) determine whether our prepharmacy program called "Professional Identity and Me" (PRIME) could enhance learners' self-awareness of their professional identity and (2) compare the effectiveness of the in-person and online versions of PRIME. PRIME introduced prepharmacy students to aspects of pharmacists' professional identity including community, hospital, and interprofessional work, as well as mental health, wellness, and time and stress management skills, Top-200 drugs, prerequisite foundational sciences, and calculations. Concepts of professionalism, graduate writing, and ownership were also presented. Bridging exercises were introduced to exemplify application. We used a mixed-methods approach to assess the outcomes. The average performance in knowledge-based assessments increased before and after the PRIME program from 53.8 to 74.6% and from 47.7 to 75.9%, while the difference in the test scores was statistically significant, with a 21% increase (p < 0.001, 95% CI 15−26%) and a 28% improvement (p < 0.001, 95% CI 23−34%) for face-to-face versus virtual PRIME. The results of a student perception survey revealed PRIME was equally effective as a virtual program during the COVID-19 pandemic, suggesting transferability to other pharmacy programs.

Guidelines for Assessing and Enhancing the Organizational Vitality of Pharmacy Educational Programs: A Call to Action!

Organizational vitality encompasses organizational mission and identity, organizational purpose and values, and employee engagement, cohesiveness, anxiety, and information sharing. Using the organizational vitality framework consisting of the following five pillars: (1) human, (2) knowledge, (3) intellectual, (4) financial capital, and (5) market value, we propose a reflection guide and specific calls to action for academic leaders including deans, department chairs, assistant/associate deans, and others within pharmacy and healthcare education systems. Our overall aim is to provide a blueprint for academic leaders to assess and enhance the organizational health, vitality, resiliency, and sustainability of their pharmacy educational programs using an established organizational vitality framework. This guide can help academic leaders at all levels to reflect on their organization's vitality and use the steps outlined here to renew conversations about faculty life, identities as leaders, the global pharmacy Academy's core mission and values, and the pursuit of work-life harmony in the context of their pharmacy schools' organizational vitality. All leaders within pharmacy educational programs should identify and embrace a holistic and guided framework that emphasizes organizational vitality.

Closing the Integration Gap: A Pilot for Incorporating Foundational Sciences, DEI-Decision Making, Empathy, and Communication for Congestive Heart Failure and Arrhythmia Management by Pharmacy Students.

Pharmacists must integrate foundational sciences with pharmacy practice for providing optimal patient care. Pharmacy students need to be trained to provide culturally competent, linguistically accessible, and empathetic care while integrating foundational science principles. However, such holistic integration is challenging to achieve and assess. To bridge this gap, we implemented and assessed an "integrated cardiovascular simulation" (ICS) module for P2 students, employing case-based and team-based learning. ICS focused on congestive heart failure with preexisting arrhythmia and incorporated patient counseling relating to diversity factors such as cultural competency, linguistic challenges, and the impact of population diversity on cardiac diseases. Students learned the SBAR communication technique (situation, background, assessment, and recommendation) and recommended therapy while elaborating on drug MOA and adverse effects. ICS was assessed through pre-and post-session quizzes and perception data immediately after the activity, and after two years, when students progressed to the cardiovascular APPE block. Student performance improved on a post-test (80.2%) compared to the pre-test (66.9%), p < 0.01 paired student t-test, with an increase in symptom and arrhythmia pattern recognition (41.2% and 36.7%, respectively). ICS was effective for teaching (1) arrhythmia pathophysiology (85%), (2) EKG interpretation (89%), (3) drug adverse effects (93%), (4) DEI-clinical decision making (92%), and (5) communication skills (85%).

COVID-19-Driven Improvements and Innovations in Pharmacy Education: A Scoping Review.

The COVID-19 pandemic led to many colleges of pharmacy having to make major changes relating to their infrastructure and delivery of their curriculum within a very short time frame, including the transition of many components to an online setting. This scoping review sought to summarize what is known about the impact of COVID-19 on pharmacy education and the effectiveness of adaptation strategies which were put in place. PubMed, Web of Science, OVID Medline, and MedEdPortal were searched to identify pharmacy education-related articles published since the beginning of the COVID-19 pandemic. For article inclusion, the following criteria had to be met: described original research, related directly to PharmD or PharmBS education, related to the impact of COVID-19 on pharmacy education, and was available in English. Out of a total of 813 articles, 50 primary research articles were selected for inclusion. Our review of these identified four domains relating to the impact of COVID-19 on pharmacy education and/or effectiveness of adaptation strategies: (1) lab-based courses and activities (including interprofessional education activities), (2) experiential education, (3) didactic education, and (4) student well-being. The key research findings are summarized and discussed. While the COVID-19 pandemic has clearly brought many challenges to pharmacy education, it has also led to key improvements and innovations.

Cardiolipin affects the supramolecular organization of ATP synthase in mitochondria.

F(1)F(0) ATP synthase forms dimers that tend to assemble into large supramolecular structures. We show that the presence of cardiolipin is critical for the degree of oligomerization and the degree of order in these ATP synthase assemblies. This conclusion was drawn from the statistical analysis of cryoelectron tomograms of cristae vesicles isolated from Drosophila flight-muscle mitochondria, which are very rich in ATP synthase. Our study included a wild-type control, a cardiolipin synthase mutant with nearly complete loss of cardiolipin, and a tafazzin mutant with reduced cardiolipin levels. In the wild-type, the high-curvature edge of crista vesicles was densely populated with ATP synthase molecules that were typically organized in one or two rows of dimers. In both mutants, the density of ATP synthase was reduced at the high-curvature zone despite unchanged expression levels. Compared to the wild-type, dimer rows were less extended in the mutants and there was more scatter in the orientation of dimers. These data suggest that cardiolipin promotes the ribbonlike assembly of ATP synthase dimers and thus affects lateral organization and morphology of the crista membrane.

Use of Team-Based Learning Pedagogy to Prepare for a Pharmacy School Accreditation Self-Study.

Ensuring adequate engagement and preparation of all stakeholders in an accreditation self-study can be challenging for many reasons, including lack of motivation and inadequate understanding of expectations and procedures. The goal of this exploratory study was to determine whether using team-based learning (TBL) pedagogy to deliver an accreditation preparation workshop could effectively prepare and engage participants. A Likert-scale questionnaire was administered to workshop attendees (n = 52) to determine whether they found TBL-based training helpful and whether it promoted engagement. Twenty-four attendees completed the survey (46%). More than 80% of participants strongly agreed or agreed with 12 statements relating to perceptions of self and participant engagement within team activities and the usefulness of team activities. More than 65% of participants strongly agreed or agreed with statements relating to the helpfulness of the TBL approach in preparing for the self-study (five questions). Subgroup analysis showed no significant difference in responses based on whether on not participants had previously been involved in an accreditation self study. Our data indicate that a TBL approach can be an effective way to engage and prepare stakeholders for an accreditation self-study, and that TBL pedagogy has utility outside of the classroom setting.

Characterization of tafazzin splice variants from humans and fruit flies.

The tafazzin gene encodes a phospholipid-lysophospholipid transacylase involved in cardiolipin metabolism, but it is not known why it forms multiple transcripts as a result of alternative splicing. Here we studied the intracellular localization, enzymatic activity, and metabolic function of four isoforms of human tafazzin and three isoforms of Drosophila tafazzin upon expression in different mammalian and insect systems. When expressed in HeLa cells, all isoforms were localized in mitochondria except for the B-form of Drosophila tafazzin, which was associated with multiple intracellular membranes. Among the human isoforms, only full-length tafazzin (FL) and tafazzin lacking exon 5 (Delta5) had transacylase activity, and only these two isoforms were able to restore a normal cardiolipin pattern, normal respiratory activity of mitochondria, and male fertility in tafazzin-deficient flies. Both FL and Delta5 were associated with large protein complexes in 293T cell mitochondria, but treatment with alkali and proteinase K suggested that the Delta5 isoform was more integrated into the hydrophobic core of the membrane than the FL isoform. Although all Drosophila isoforms showed transacylase activity in vitro, only the A-form supported cardiolipin remodeling in flies. The data suggest that humans express two mitochondrial isoenzymes of tafazzin that have similar transacylase activities but different membrane topologies. Furthermore, the data show that the expression of human tafazzin in flies creates cardiolipin with a Drosophila pattern, suggesting that the characteristic fatty acid profile of cardiolipin is not determined by the substrate specificity of tafazzin.

Formation of molecular species of mitochondrial cardiolipin. 1. A novel transacylation mechanism to shuttle fatty acids between sn-1 and sn-2 positions of multiple phospholipid species.

Mitochondrial cardiolipin undergoes extensive remodeling of its acyl groups to generate uniformly substituted species, such as tetralinoleoyl-cardiolipin, but the mechanism of this remodeling has not been elucidated, except for the fact that it requires tafazzin. Here we show that purified recombinant Drosophila tafazzin exchanges acyl groups between cardiolipin and phosphatidylcholine by a combination of forward and reverse transacylations. The acyl exchange is possible in the absence of phospholipase A(2) because it requires only trace amounts of lysophospholipids. We show that purified tafazzin reacts with various phospholipid classes and with various acyl groups both in sn-1 and sn-2 position. Expression studies in Sf9 insect cells suggest that the effect of tafazzin on cardiolipin species is dependent on the cellular environment and not on enzymatic substrate specificity. Our data demonstrate that tafazzin catalyzes general acyl exchange between phospholipids, which raises the question whether pattern formation in cardiolipin is the result of the equilibrium distribution of acyl groups between multiple phospholipid species.