High expression of oleoyl-ACP hydrolase underpins life-threatening respiratory viral diseases.

Respiratory infections cause significant morbidity and mortality, yet it is unclear why some individuals succumb to severe disease. In patients hospitalized with avian A(H7N9) influenza, we investigated early drivers underpinning fatal disease. Transcriptomics strongly linked oleoyl-acyl-carrier-protein (ACP) hydrolase (OLAH), an enzyme mediating fatty acid production, with fatal A(H7N9) early after hospital admission, persisting until death. Recovered patients had low OLAH expression throughout hospitalization. High OLAH levels were also detected in patients hospitalized with life-threatening seasonal influenza, COVID-19, respiratory syncytial virus (RSV), and multisystem inflammatory syndrome in children (MIS-C) but not during mild disease. In olah-/- mice, lethal influenza infection led to survival and mild disease as well as reduced lung viral loads, tissue damage, infection-driven pulmonary cell infiltration, and inflammation. This was underpinned by differential lipid droplet dynamics as well as reduced viral replication and virus-induced inflammation in macrophages. Supplementation of oleic acid, the main product of OLAH, increased influenza replication in macrophages and their inflammatory potential. Our findings define how the expression of OLAH drives life-threatening viral disease.

A three-stage intrathymic development pathway for the mucosal-associated invariant T cell lineage.

Mucosal-associated invariant T cells (MAIT cells) detect microbial vitamin B2 derivatives presented by the antigen-presenting molecule MR1. Here we defined three developmental stages and checkpoints for the MAIT cell lineage in humans and mice. Stage 1 and stage 2 MAIT cells predominated in thymus, while stage 3 cells progressively increased in abundance extrathymically. Transition through each checkpoint was regulated by MR1, whereas the final checkpoint that generated mature functional MAIT cells was controlled by multiple factors, including the transcription factor PLZF and microbial colonization. Furthermore, stage 3 MAIT cell populations were expanded in mice deficient in the antigen-presenting molecule CD1d, suggestive of a niche shared by MAIT cells and natural killer T cells (NKT cells). Accordingly, this study maps the developmental pathway and checkpoints that control the generation of functional MAIT cells.

Long-Term Outcomes of Mechanical Aortic Valve Replacement in Children.

When the options of aortic valve repair or the Ross procedure are not feasible or have been exhausted, mechanical aortic valve replacement (AVR) may provide a reliable and structurally durable alternative, but with the limitations of long-term anticoagulation, thrombosis risk and lack of valve growth potential. In this article, we review the longitudinal outcomes of mechanical AVR in children in our institution and compare them to those recently reported by others. From 1978 to 2020, 62 patients underwent mechanical AVR at a median age of 12.4 years (interquartile range (IQR): 8.6-16.8 years). The most common underlying diagnoses were: conotruncal anomalies (40%, 25/62), congenital aortic stenosis (16%, 10/62), rheumatic valve disease (16%, 10/62), connective tissue disease (8.1%, 5/62) and infective endocarditis (6.5%, 4/62). Thirty-two patients (52%, 32/62) had at least 1 prior aortic valve surgery prior to mechanical AVR. Early death was 3.2% (2/62). Median follow-up was 14.4 years (IQR: 8.4-28.2 years). Kaplan-Meier survival was 96.8%, 91.9%, 86.3%, and 81.9% at 1, 5, 10, and 20 years. On competing risk analysis, the proportion of patients alive without aortic valve reoperation at 1, 5, 10, and 20 years was 95.2%, 87.0%, 75.5% and 55.4%, respectively, while the proportion of patients that had aortic valve reoperation (with death as a competing event) at 1, 5, 10, and 20 years was 1.6%, 4.9%, 12.8%, and 28.5%, respectively. In conclusion, when the options of aortic valve repair or the Ross procedure are not feasible in children, mechanical AVR is an alternative, yet the long-term rates of mortality and need for aortic valve reoperation are of concern.

Clinical assessment can be lifesaving: Salvage of catastrophic cerebral ischemia by conversion to central extracorporeal membrane oxygenation.

Peripheral veno-artertial extracorporeal membrane oxygenation (VA-ECMO) is commonly used in the paediatric population for intractable respiratory and cardiac failure. One of the devastating complications of VA-ECMO is severe brain damage due to ischemia or haemorrhage. We describe a case of peripheral cervical VA-ECMO complicated by evolving right cerebral ischemia which was rescued with rapid conversion from peripheral to central VA-ECMO support. Notably, the patient had a complete circle of Willis. Following conversion, we observed complete resolution of neurological symptoms with full functional recovery.

Heart Transplantation after Univentricular Palliation: Improved Outcomes and Increased Complexity.

AIM: Heart transplantation (HT) in patients with failing univentricular circulation is often challenging. This is compounded by the ever-increasing number of patients with prior Norwood-type reconstruction of the aorta, large aortic root, and often dense adhesions from multiple prior operations. We aimed to elucidate differences in outcomes of HT in patients with prior univentricular palliations, with and without prior Norwood-type aortic arch reconstruction (ArchRec). METHODS: All patients who underwent HT for failed univentricular palliation during the 1990-2022 period were included in the study. RESULTS: Of 45 patients, 18 had undergone ArchRec. Hospital mortality improved in the recent era (17.4% before 2006 vs 0% after 2006; p=0.11), despite a higher proportion of patients with ArchRec (17.4% before 2006 vs 60.8% after 2006, p=0.002). Patients with ArchRec had a higher number of prior cardiac surgeries (4.1±1.5 vs 3.2±1.3, p=0.04), longer cardiopulmonary bypass time (320±23 vs 242±21 min, p=0.02), more concomitant arch reconstruction (33.3% vs 0%, p=0.02), greater need for post-HT extracorporeal membrane oxygenation (33.3% vs 3.7%; p=0.01) and longer hospital stay (37.1±30.5 days vs 23.6±11.8 days, p=0.04). Freedom from death or retransplantation for all patients was 91%, 73%, 67%, and 53% at 1, 5, 10, and 15-years, respectively. Prior ArchRec, Fontan procedure, and earlier eras were not risk factors for death. CONCLUSIONS: The outcomes of HT after univentricular palliation have improved in recent times and low operative mortality can be achieved. Despite increased complexity, good similar outcomes can be achieved in patients with and without prior arch reconstruction regardless of the palliation stage.

Ethical analysis of the first porcine cardiac xenotransplantation.

In this article, we provide an ethical analysis of the first porcine cardiac xenotransplant, performed in Maryland, USA in early 2022. David Bennett was offered the experimental procedure after he was deemed ineligible for human heart transplantation and mechanical circulatory support, based on a history of non-compliance. It was reported that Mr Bennett's previous instances of non-compliance were for medically non-life-threatening conditions years earlier, where the risks of non-compliance were not as high. We argue that, in Mr Bennett's case, a history of non-compliance in a different context, should not necessarily rule him ineligible for a potentially life-saving treatment now. Furthermore, using previous non-compliance to exclude individuals from donor organs may have the unintended effect of placing the burden of testing xenotransplantation on those who are already disadvantaged. We then argue that it is not enough to rely on patient consent to ethically justify xenotransplantation research. Taking a broad ethical perspective is crucial when mapping a clinical pathway for xenotransplantation.

Congenital Aortic Valve Repair When the Options aren't Good: Truncus Arteriosus and Transposition of the Great Arteries.

Patients with truncus arteriosus and transposition of great arteries are prone to neo-aortic valve insufficiency. Although presenting at opposite ends of the age spectrum, both conditions tend to be commonly associated with neo aortic root dilatation. In patients with truncus arteriosus there is an additional complexity of quadricuspid valve morphology, which make up the majority of valves requiring repair. A unified approach to all these patients would include reduction and stabilization of the annulus and sinotubular junction, as well as achieving equal and symmetrical coaptation of the valve leaflets. By systematically employing these techniques, valve replacement should be avoidable in most children.

Outcomes of the Arterial Switch Operation in Patients With Dextrocardia.

BACKGROUND: Patients with dextrocardia and d-transposition of the great arteries (d-TGA) present a technical challenge when performing the arterial switch operation (ASO). We sought to determine the long-term outcomes of this rare presentation. METHODS: All patients who underwent the ASO with d-TGA and dextrocardia were identified from the hospital database. RESULTS: There were four patients with dextrocardia (4 of 844, 0.5%) patients; two patients had situs solitus and two patients had situs inversus. Three patients had a ventricular septal defect. Left ventricular outflow tract obstruction was present in one patient and one patient had a hypoplastic arch with severe coarctation of aorta. Anomalous coronary anatomy occurred in two patients. There was one early mortality and the cause of death was sepsis. One patient required late reoperation for severe neo-pulmonary valve regurgitation at 23 years after the ASO. At last follow-up, all three surviving patients were in New York Heart Association Class I. CONCLUSIONS: Patients with d-TGA and dextrocardia who undergo the ASO are extremely rare and require challenging operative management.

The Ross Procedure in Children: Defining the Optimal Age.

BACKGROUND: It has been proposed that delaying the Ross procedure to later in childhood, allowing autograft stabilisation and placement of a larger pulmonary conduit, may improve outcomes. However, the effect of age at the time of Ross procedure on outcomes remains unclear. METHODS: All patients who underwent the Ross procedure between 1995 and 2018 were included in the study. Patients were divided into four groups: infants, age 1 to 5 years, age 5 to 10 years and age 10 to 18 years. RESULTS: A total of 140 patients underwent the Ross procedure in the study period. Early mortality was 23.3% (7/30) for infants compared to 0% for older children (p<0.001). Survival at 15 years was significantly lower in infants (76.3%±9.9%), compared to children aged 1 to 5 years (90.9%±20.1%), 5 to 10 years (94%±13.3%), and 10 to 18 years (86.7%±10.0%), p=0.01. Freedom from autograft reoperation at 15 years was significantly lower in infants (58.4%±16.2%), compared to children aged 1 to 5 years (77.1%±14.9%), 5 to 10 years (84.2%±6.0%) and 10 to 18 years (87.8%±9.0%), p=0.01. Overall freedom from reoperation at 15 years was 13.0%±6.0% for infants, 24.2%±9.0% for children aged 1 to 5 years, 46.7%±15.8% for children aged 5 to 10 years, and 78.4%±10.4%, p<0.001. CONCLUSIONS: The Ross procedure performed after 10 years of age appears to be associated with improved freedom from reoperation, primarily due to a reduction in reoperation on the pulmonary conduit.

Sex-Specific Control of Human Heart Maturation by the Progesterone Receptor.

BACKGROUND: Despite in-depth knowledge of the molecular mechanisms controlling embryonic heart development, little is known about the signals governing postnatal maturation of the human heart. METHODS: Single-nucleus RNA sequencing of 54 140 nuclei from 9 human donors was used to profile transcriptional changes in diverse cardiac cell types during maturation from fetal stages to adulthood. Bulk RNA sequencing and the Assay for Transposase-Accessible Chromatin using sequencing were used to further validate transcriptional changes and to profile alterations in the chromatin accessibility landscape in purified cardiomyocyte nuclei from 21 human donors. Functional validation studies of sex steroids implicated in cardiac maturation were performed in human pluripotent stem cell-derived cardiac organoids and mice. RESULTS: Our data identify the progesterone receptor as a key mediator of sex-dependent transcriptional programs during cardiomyocyte maturation. Functional validation studies in human cardiac organoids and mice demonstrate that the progesterone receptor drives sex-specific metabolic programs and maturation of cardiac contractile properties. CONCLUSIONS: These data provide a blueprint for understanding human heart maturation in both sexes and reveal an important role for the progesterone receptor in human heart development.

A high-dimensional cytometry atlas of peripheral blood over the human life span.

Age can profoundly affect susceptibility to a broad range of human diseases. Children are more susceptible to some infectious diseases such as diphtheria and pertussis, while in others, such as coronavirus disease 2019 and hepatitis A, they are more protected compared with adults. One explanation is that the composition of the immune system is a major contributing factor to disease susceptibility and severity. While most studies of the human immune system have focused on adults, how the immune system changes after birth remains poorly understood. Here, using high-dimensional spectral flow cytometry and computational methods for data integration, we analyzed more than 50 populations of immune cells in the peripheral blood, generating an immune cell atlas that defines the healthy human immune system from birth up to 75 years of age. We focused our efforts on children under 18 years old, revealing major changes in immune cell populations after birth and in children of schooling age. Specifically, CD4+ T effector memory cells, Vδ2+ gamma delta (γδ)T cells, memory B cells, plasmablasts, CD11c+ B cells and CD16+ CD56bright natural killer (NK) cells peaked in children aged 5-9 years old, whereas frequencies of T helper 1, T helper 17, dendritic cells and CD16+ CD57+ CD56dim NK cells were highest in older children (10-18 years old). The frequency of mucosal-associated invariant T cells was low in the first several years of life and highest in adults between 19 and 30 years old. Late adulthood was associated with fewer mucosal-associated invariant T cells and Vδ2+ γδ T cells but with increased frequencies of memory subsets of B cells, CD4+ and CD8+ T cells and CD57+ NK cells. This human immune cell atlas provides a critical resource to understand changes to the immune system during life and provides a reference for investigating the immune system in the context of human disease. This work may also help guide future therapies that target specific populations of immune cells to protect at-risk populations.

Poorer Self-Reported Physical Health and Higher Anxiety Trait in Young Adults With Previous Coarctation Repair.

BACKGROUND: Little is known about the impact of a coarctation repair on the functional outcomes of young adults. This study aimed to determine (1) the functional and mental health status in young adults with previous coarctation repair, and (2) the impact of late hypertension on their quality of life. METHODS: A cross-sectional study using validated self-reported questionnaires (Short Form 36 version 2 [SF-36v2], Beck Depression Inventory [BDI], and State-Trait Anxiety Inventory [STAI]) was performed in 54 patients aged 15-47 years with previous paediatric coarctation repair. Questionnaire scores were compared to healthy age- and gender-matched controls. Patients' previously published 24-hour blood pressure monitoring results were included. RESULTS: Late hypertension was present in 64% (34/54) at a mean of 29±8 years after coarctation repair. SF-36v2 mean physical component summary score was significantly lower in coarctation patients compared with controls (53.1±6.8 vs 56.0±4.7, p=0.02), but there was no significant difference in mean mental component summary score (p=0.2). SF-36v2 mean role emotional score tended to be associated with 10 mmHg increases in mean 24-hour systolic blood pressure (regression coefficient 4.3 p=0.06). STAI mean trait anxiety score tended to be higher in coarctation patients compared with controls (36.6±9.0 vs 33.5±7.8, p=0.06). There was no significant difference in BDI scores between patients and controls. CONCLUSIONS: Young adults with previous coarctation repair report poorer physical health and tended towards higher anxiety trait compared to healthy controls. Strategies to improve self-reported physical health and anxiety should be explored. Long-term assessment of quality of life outcomes in coarctation patients is warranted.

Balloon dilatation versus surgical valvotomy for congenital aortic stenosis: a propensity score matched study.

BACKGROUND: Balloon valvuloplasty and surgical aortic valvotomy have been the treatment mainstays for congenital aortic stenosis in children. Choice of intervention often differs depending upon centre bias with limited relevant, comparative literature. OBJECTIVES: This study aims to provide an unbiased, contemporary matched comparison of these balloon and surgical approaches. METHODS: Retrospective analysis of patients with congenital aortic valve stenosis who underwent balloon valvuloplasty (Queensland Children's Hospital, Brisbane) or surgical valvotomy (Royal Children's Hospital, Melbourne) between 2005 and 2016. Patients were excluded if pre-intervention assessment indicated ineligibility to either group. Propensity score matching was performed based on age, weight, and valve morphology. RESULTS: Sixty-five balloon patients and seventy-seven surgical patients were included. Overall, the groups were well matched with 18 neonates/25 infants in the balloon group and 17 neonates/28 infants in the surgical group. Median age at balloon was 92 days (range 2 days - 18.8 years) compared to 167 days (range 0 days - 18.1 years) for surgery (rank-sum p = 0.08). Mean follow-up was 5.3 years. There was one late balloon death and two early surgical deaths due to left ventricular failure. There was no significant difference in freedom from reintervention at latest follow-up (69% in the balloon group and 70% in the surgical group, p = 1.0). CONCLUSIONS: Contemporary analysis of balloon aortic valvuloplasty and surgical aortic valvotomy shows no difference in overall reintervention rates in the medium term. Balloon valvuloplasty performs well across all age groups, achieving delay or avoidance of surgical intervention.

Atrial Septal Defect Closure via Ministernotomy in Children.

Atrial septal defect (ASD) closure is usually performed in children via a conventional sternotomy. In striving to improve the cosmetic result, we have adopted a lower ministernotomy approach with a very small skin incision. We present a single surgeon experience of 110 consecutive patients undergoing surgical closure of ASD, comparing conventional (n=55) and mini-sternotomy (n=55) approaches. Our ministernotomy technique avoids direct superior vena cava cannulation, allowing for a smaller incision, while providing adequate exposure. The ministernotomy approach is safe and provides an excellent cosmetic result.

Berlin Heart EXCOR Support in the First Year of Life: A Single Centre Experience.

BACKGROUND: Berlin Heart EXCOR Pediatric Ventricular Assist Device (BHE) (Berlin Heart AG, Berlin, Germany, BHE) is used worldwide for mechanical circulatory support as a bridge to transplantation or recovery for children with end-stage heart failure. The study aim was to evaluate morbidity and mortality of children less than one year old supported with BHE to identify predictors of adverse outcomes. METHODS: Data of all children aged less than one year supported with BHE between 2005 and 2018 at the Royal Children's Hospital, Melbourne were reviewed. Adverse events were defined using PediMACS criteria. RESULTS: Fourteen (14) children under 1 year of age were implanted with BHE at a median age and weight of 0.37 years (IQR 0.09-0.7) and 5.7 kg (IQR 3.5-7.95) respectively. Four (4) patients were neonates, and 10 were older infants. Twelve (12) patients had cardiomyopathy and two, myocarditis. Preoperative extracorporeal membrane oxygenation (ECMO) support was required in six patients for a mean of 9 days (IQR 6-13). Sepsis occurred in five patients (36%) and thromboembolic stroke in two patients (14%). Survival to bridge to transplantation (11) and recovery (1) was achieved in 12 patients (86%). Mortality was 14%. The median duration of BHE support was 110 days (IQR 40-161). Both patients who died were neonates with myocarditis and required surgical re-intervention during BHE support. CONCLUSIONS: BHE provides excellent support as a bridge to transplantation or recovery in infants, with a low incidence of neurological dysfunction. Neonates with myocarditis may be at greater risk for death after BHE implantation.

Single-ventricle palliation in children with atrioventricular septal defect and transposition of the great arteries: 45 years of experience.

BACKGROUND: The association of atrioventricular septal defect and transposition of the great arteries is very rare. As a rule, these patients have unbalanced ventricles. However, there have been no studies describing the results of single-ventricle palliation in these children. METHODS: All children who underwent surgery with a diagnosis of atrioventricular septal defect and transposition of the great arteries were included in the study. Data were obtained from medical records. RESULTS: A total of 38 patients with atrioventricular septal defect and transposition of the great arteries underwent single-ventricle palliation at the study institution between 1971 and 2016. The mean follow-up was 12.4 years (median: 14.6 years, range 2-43.3 years). Most children had unbalanced atrioventricular septal defect (94.7%, 36/38). Survival was 67.6% (95% confidence interval [CI]: 50.0-80.2%) at 10 years and 57.8% (95% CI: 38.0-73.4%) at 20 years. By 10 years, 58.6% (95% CI: 40.8-72.7%) had progressed to Fontan completion, while 32.5% (95% CI: 18.2-47.6%) had died. In patients achieving Fontan completion, 20-year event-free survival was 73.3% (95% CI: 34.8-91.3%), while 5.0% (95% CI: 0.4-20.5%) had undergone cardiac transplantation and 21.7% (95% CI: 3.2-50.8%) had undergone takedown of the Fontan circulation. Freedom from atrioventricular valve surgery was 57.0% (95% CI: 37.2-72.7%) at 10 and 20 years. CONCLUSIONS: The association of atrioventricular septal defect and transposition of the great arteries is very rare, and most of these children have unbalanced ventricles. Single-ventricle palliation results in 25-year overall survival of 50%. However, in patients, who had Fontan completion, survival was 75% at 25 years after Fontan operation.

Pregnancy Outcomes in Women After the Arterial Switch Operation.

BACKGROUND: Pregnancy outcomes after the arterial switch operation (ASO) are rare. We sought to determine outcomes of ASO survivors who underwent pregnancy. METHODS: Female patients who had an ASO and underwent pregnancy were identified from the congenital heart disease pregnancy clinic at The Royal Melbourne Hospital. All follow-up data were collected retrospectively by medical record review. RESULTS: Eleven (11) women were identified as having undergone medical care during pregnancy, from the adult congenital database, at The Royal Melbourne Hospital. There were 17 successful pregnancies, and nine women have been followed post pregnancy. Of the 17 successful deliveries, eight were delivered by Caesarean section, seven were vaginal deliveries and two were instrumented vaginal deliveries. Of the eight Caesarean sections, five were emergency and three were elective. The indications for emergency Caesarean section were obstructed labour (n = 2), abnormal cardiotocography (n = 1), obstructed labour and abnormal cardiotocography (n = 1) and congestive cardiac failure (n = 1). There was one neonatal complication (respiratory distress requiring intubation) in a child born at 31 weeks. There were maternal obstetric complications in 10 patients. There were two maternal cardiac complications during pregnancy (heart failure and rapid atrial fibrillation/flutter). There was no change in left ventricular function post-pregnancy. There was progression of severity of neo-aortic valve regurgitation in two patients post pregnancy (trivial to mild and moderate-severe to severe respectively). CONCLUSION: Pregnancy post ASO appears to be safe in the majority of women. Maternal cardiac complications are uncommon in patients without residual significant haemodynamic lesions, although maternal obstetric complications may be common.

Rare Association of an Intramural Coronary Artery and Truncus Arteriosus.

The association of truncus arteriosus (TA) and an intramural coronary artery is rare. Seven (7) patients had TA and an intramural coronary artery at the Royal Children's Hospital, Melbourne between 1996 and 2018. Four (4) patients underwent concomitant unroofing of their intramural coronary artery. One (1) patient who did not undergo concomitant unroofing had a cardiac arrest on postoperative day 1 and subsequently underwent reoperation for coronary unroofing. Given the potential for serious complications, patients with TA and an intramural coronary artery may benefit from coronary unroofing with creation of a generous neo-ostium.

Divergent SATB1 expression across human life span and tissue compartments.

Special AT-rich binding protein-1 (SATB1) is a global chromatin organizer capable of activating or repressing gene transcription in mice and humans. The role of SATB1 is pivotal for T-cell development, with SATB1-knockout mice being neonatally lethal, although the exact mechanism is unknown. Moreover, SATB1 is dysregulated in T-cell lymphoma and proposed to suppress transcription of the Pdcd1 gene, encoding the immune checkpoint programmed cell death protein 1 (PD-1). Thus, SATB1 expression in T-cell subsets across different tissue compartments in humans is of potential importance for targeting PD-1. Here, we comprehensively analyzed SATB1 expression across different human tissues and immune compartments by flow cytometry and correlated this with PD-1 expression. We investigated SATB1 protein levels in pediatric and adult donors and assessed expression dynamics of this chromatin organizer across different immune cell subsets in human organs, as well as in antigen-specific T cells directed against acute and chronic viral infections. Our data demonstrate that SATB1 expression in humans is the highest in T-cell progenitors in the thymus, and then becomes downregulated in mature T cells in the periphery. Importantly, SATB1 expression in peripheral mature T cells is not static and follows fine-tuned expression dynamics, which appear to be tissue- and antigen-dependent. Furthermore, SATB1 expression negatively correlates with PD-1 expression in virus-specific CD8+ T cells. Our study has implications for understanding the role of SATB1 in human health and disease and suggests an approach for modulating PD-1 in T cells, highly relevant to human malignancies or chronic viral infections.

Remote ischaemic preconditioning modifies serum apolipoprotein D, met-enkephalin, adenosine, and nitric oxide in healthy young adults.

Remote ischaemic preconditioning (RIPC) has been employed as a non-invasive protective intervention against myocardial ischaemia-reperfusion injury in animal studies. However, the underlying mechanisms are incompletely defined in humans and its clinical efficacy has been inconclusive. As advanced age, disease, and drugs may confound RIPC mechanisms in patients, our aim is to measure whether RIPC evokes release of adenosine, bradykinin, met-enkephalin, nitric oxide, and apolipoproteins in healthy young adults. Healthy subjects (n = 18, 9 males, 23 ± 1.5 years old; 9 females, 23 ± 1.8 years old) participated after informed consent. RIPC was applied using a blood pressure cuff to the dominant arms for four cycles of 5-minute cuff inflation (ischaemia) and 5-minute cuff deflation (reperfusion). Blood was sampled at baseline and immediately after the final cuff deflation (Post-RIPC). Baseline and Post-RIPC plasma levels of adenosine, bradykinin, met-enkephalin, apolipoprotein A-1 (ApoA-1), apolipoprotein D (ApoD), and nitric oxide (as nitrite) were measured via ELISA and high-performance liquid chromatography. Mean (±SD) baseline levels of adenosine, bradykinin, met-enkephalin, ApoA-1, ApoD, and nitrite in healthy young adults were 13.8 ± 6.5 ng/mL, 2.6 ± 1.9 µg/mL, 594.1 ± 197.4 pg/mL, 3.0 ± 0.7 mg/mL, 22.2 ± 4.0 µg/mL, and 49.8 ± 13.4 nmol/L, respectively. Post-RIPC adenosine and nitrite levels increased (59.5 ± 37.9%, P < .0001; 32.2 ± 19.5%, P < .0001), whereas met-enkephalin and ApoD levels marginally decreased (5.3 ± 14.0%, P = .04; 10.8 ± 20.5%, P = .04). Post-RIPC levels were not influenced by sex, age, blood pressure, waist circumference, or BMI. RIPC produces increased levels of adenosine and nitrites, and decreased met-enkephalin and ApoD in the plasma of young healthy adults.