Communicating Mass Spectrometry Quality Information in mzQC with Python, R, and Java.

Mass spectrometry is a powerful technique for analyzing molecules in complex biological samples. However, inter- and intralaboratory variability and bias can affect the data due to various factors, including sample handling and preparation, instrument calibration and performance, and data acquisition and processing. To address this issue, the Quality Control (QC) working group of the Human Proteome Organization's Proteomics Standards Initiative has established the standard mzQC file format for reporting and exchanging information relating to data quality. mzQC is based on the JavaScript Object Notation (JSON) format and provides a lightweight yet versatile file format that can be easily implemented in software. Here, we present open-source software libraries to process mzQC data in three programming languages: Python, using pymzqc; R, using rmzqc; and Java, using jmzqc. The libraries follow a common data model and provide shared functionalities, including the (de)serialization and validation of mzQC files. We demonstrate use of the software libraries in a workflow for extracting, analyzing, and visualizing QC metrics from different sources. Additionally, we show how these libraries can be integrated with each other, with existing software tools, and in automated workflows for the QC of mass spectrometry data. All software libraries are available as open source under the MS-Quality-Hub organization on GitHub (https://github.com/MS-Quality-Hub).

Prevalence of polypharmacy and drug interaction in older adults with rheumatic disease.

INTRODUCTION/AIM: Older people with rheumatic diseases tend to have a greater number of associated comorbidities, which will require the use of more drugs, increasing the risk of hospitalizations, complications, and drug interactions. In Mexico, there has been an estimated prevalence of polypharmacy of up to 55%, however there are scarce reports on the topic in our elderly population with rheumatic diseases. We aimed to determine the prevalence of polypharmacy and the association of drug interactions in patients treated for rheumatic disease. METHODS: A retrospective observational study was conducted on patients undergoing treatment for rheumatic diseases who were treated in geriatrics and rheumatology clinics from January to December 2021. The presence of polypharmacy and drug interactions was evaluated using the BOT Plus Pharmacological Surveillance System. The prevalence of polypharmacy and the association of drug interactions were estimated. RESULTS: We evaluated 320 patients, with a mean age of 67.05±5.8 years, predominantly female (85%). The prevalence of polypharmacy was 68.1% (n=218), of which 214 (98.1%) patients had related drug interactions; 27.1% were severe and 53.2% as moderate interactions. Factors related with increased risk of drug interactions were being exposed to hypertension increased the risk of drug interactions (POR 1.75, 95% CI 1.44-2.14; P<0.001), having osteoarthritis (POR 1.21, 95% CI 1.04-1.42; P=0.032) and thyroid disease (POR 1.45, 95% CI 1.28-1.65; P=0.001). The most prevalent serious interactions were leflunomide-methotrexate in 27 (46.5%) patients and buprenorphine-tramadol in 8 (13.7%). CONCLUSIONS: A high prevalence of polypharmacy and drug interactions was observed in elderly patients with rheumatic diseases. The main associated factors were comorbidities, particularly high blood pressure, osteoarthritis and thyroid diseases.

Update of the guidelines for the pharmacological treatment of rheumatoid arthritis by the Mexican College of Rheumatology 2023.

OBJECTIVE: To develop updated guidelines for the pharmacological management of rheumatoid arthritis (RA). METHODS: A group of experts representative of different geographical regions and various medical services catering to the Mexican population with RA was formed. Questions based on Population, Intervention, Comparison, and Outcome (PICO) were developed, deemed clinically relevant. These questions were answered based on the results of a recent systematic literature review (SLR), and the evidence's validity was assessed using the GRADE system, considered a standard for these purposes. Subsequently, the expert group reached consensus on the direction and strength of recommendations through a multi-stage voting process. RESULTS: The updated guidelines for RA treatment stratify various therapeutic options, including different classes of DMARDs (conventional, biologicals, and JAK inhibitors), as well as NSAIDs, glucocorticoids, and analgesics. By consensus, it establishes the use of these in different subpopulations of interest among RA patients and addresses aspects related to vaccination, COVID-19, surgery, pregnancy and lactation, and others. CONCLUSIONS: This update of the Mexican guidelines for the pharmacological treatment of RA provides reference points for evidence-based decision-making, recommending patient participation in joint decision-making to achieve the greatest benefit for our patients. It also establishes recommendations for managing a variety of relevant conditions affecting our patients.

The mitochondrial multi-omic response to exercise training across rat tissues.

Mitochondria have diverse functions critical to whole-body metabolic homeostasis. Endurance training alters mitochondrial activity, but systematic characterization of these adaptations is lacking. Here, the Molecular Transducers of Physical Activity Consortium mapped the temporal, multi-omic changes in mitochondrial analytes across 19 tissues in male and female rats trained for 1, 2, 4, or 8 weeks. Training elicited substantial changes in the adrenal gland, brown adipose, colon, heart, and skeletal muscle. The colon showed non-linear response dynamics, whereas mitochondrial pathways were downregulated in brown adipose and adrenal tissues. Protein acetylation increased in the liver, with a shift in lipid metabolism, whereas oxidative proteins increased in striated muscles. Exercise-upregulated networks were downregulated in human diabetes and cirrhosis. Knockdown of the central network protein 17-beta-hydroxysteroid dehydrogenase 10 (HSD17B10) elevated oxygen consumption, indicative of metabolic stress. We provide a multi-omic, multi-tissue, temporal atlas of the mitochondrial response to exercise training and identify candidates linked to mitochondrial dysfunction.

A prospective multicenter feasibility study of a miniaturized implantable continuous flow ventricular assist device in smaller children with heart failure.

BACKGROUND: There is no FDA-approved left ventricular assist device (LVAD) for smaller children permitting routine hospital discharge. Smaller children supported with LVADs typically remain hospitalized for months awaiting heart transplant-a major burden for families and a challenge for hospitals. We describe the initial outcomes of the Jarvik 2015, a miniaturized implantable continuous flow LVAD, in the NHLBI-funded Pumps for Kids, Infants, and Neonates (PumpKIN) study, for bridge-to-heart transplant. METHODS: Children weighing 8 to 30 kg with severe systolic heart failure and failing optimal medical therapy were recruited at 7 centers in the United States. Patients with severe right heart failure and single-ventricle congenital heart disease were excluded. The primary feasibility endpoint was survival to 30 days without severe stroke or non-operational device failure. RESULTS: Of 7 children implanted, the median age was 2.2 (range 0.7, 7.1) years, median weight 10 (8.2 to 20.7) kilograms; 86% had dilated cardiomyopathy; 29% were INTERMACS profile 1. The median duration of Jarvik 2015 support was 149 (range 5 to 188) days where all 7 children survived including 5 to heart transplant, 1 to recovery, and 1 to conversion to a paracorporeal device. One patient experienced an ischemic stroke on day 53 of device support in the setting of myocardial recovery. One patient required ECMO support for intractable ventricular arrhythmias and was eventually transplanted from paracorporeal biventricular VAD support. The median pump speed was 1600 RPM with power ranging from 1-4 Watts. The median plasma free hemoglobin was 19, 30, 19 and 30 mg/dL at 7, 30, 90 and 180 days or time of explant, respectively. All patients reached the primary feasibility endpoint. Patient-reported outcomes with the device were favorable with respect to participation in a full range of activities. Due to financial issues with the manufacturer, the study was suspended after consent of the eighth patient. CONCLUSION: The Jarvik 2015 LVAD appears to hold important promise as an implantable continuous flow device for smaller children that may support hospital discharge. The FDA has approved the device to proceed to a 22-subject pivotal trial. Whether this device will survive to commercialization remains unclear because of the financial challenges faced by industry seeking to develop pediatric medical devices. (Supported by NIH/NHLBI HHS Contract N268201200001I, clinicaltrials.gov 02954497).

The Burden of Stroke in Neonates Undergoing Congenital Heart Surgery: A Large Multicenter Analysis.

BACKGROUND: Stroke affects surgical decision making and outcomes of neonatal cardiac surgery(CHS). We sought to assess the burden of stroke in this population from a large multi-center database. METHODS: We analyzed neonates undergoing CHS with cardiopulmonary bypass from the Pediatric Health Information System database(2004-2022). The cohort was divided into stroke-group which included pre/post-op ischemic, hemorrhagic-subtypes and grade III-IV intraventricular hemorrhages and compared in-hospital and follow-up outcomes to non-stroke group. RESULTS: Of 14,228 neonates, 800(5.6%) had a peri-operative stroke. Stroke-group was more likely to have hypoplastic left-heart syndrome (HLHS)(30.5% vs 20.7%), born pre-term(19.4% vs 11.7%), low-birthweight(17.8% vs 11.9%) and require ECMO(48.8% vs 13.8%)(all, p<0.001). Outcomes comparing stroke vs no-stroke were, mortality:33.1% vs 8.9%, non-home discharge:12.5% vs 6.9%, length of stay:41 vs 24 days, hospitalization-costs:$354,521 vs $180,489(all, p<0.05). Stroke increased odds of mortality by two-fold[OR 2.20(1.75-2.77), p<0.001] after adjusting for ECMO, prematurity among other significant factors. On follow-up, stroke-group had higher incidence of hydrocephalus(9.5% vs 1.3%), cerebral palsy (6.2% vs 1.3%), autism spectrum disorder(7.1% vs 3.5%) and had higher one- and five- year mortality among survivors of index admission(5.3% and 11.3% vs 3.3% and 5.9%, respectively) (all p<0.05). CONCLUSIONS: Neonatal CHS patients born prematurely, diagnosed with HLHS or those requiring ECMO are disproportionately affected by stroke. The occurrence of stroke is marked by significantly higher mortality. Future research should seek to identify factors leading to stroke, in order to increase rescue after stroke and for improvement of long-term outcomes.

Sexual dimorphism and the multi-omic response to exercise training in rat subcutaneous white adipose tissue.

Subcutaneous white adipose tissue (scWAT) is a dynamic storage and secretory organ that regulates systemic homeostasis, yet the impact of endurance exercise training (ExT) and sex on its molecular landscape is not fully established. Utilizing an integrative multi-omics approach, and leveraging data generated by the Molecular Transducers of Physical Activity Consortium (MoTrPAC), we show profound sexual dimorphism in the scWAT of sedentary rats and in the dynamic response of this tissue to ExT. Specifically, the scWAT of sedentary females displays -omic signatures related to insulin signaling and adipogenesis, whereas the scWAT of sedentary males is enriched in terms related to aerobic metabolism. These sex-specific -omic signatures are preserved or amplified with ExT. Integration of multi-omic analyses with phenotypic measures identifies molecular hubs predicted to drive sexually distinct responses to training. Overall, this study underscores the powerful impact of sex on adipose tissue biology and provides a rich resource to investigate the scWAT response to ExT.

Flexible bronchoscopy in pediatric lung transplantation.

Pediatric lung transplantation represents a treatment option for children with advanced lung disease or pulmonary vascular disorders who are deemed an appropriate candidate. Pediatric flexible bronchoscopy is an important and evolving field that is highly relevant in the pediatric lung transplant population. It is thus important to advance our knowledge to better understand how care for children after lung transplant can be maximally optimized using pediatric bronchoscopy. Our goals are to continually improve procedural skills when performing bronchoscopy and to decrease the complication rate while acquiring adequate samples for diagnostic evaluation. Attainment of these goals is critical since allograft assessment by bronchoscopic biopsy is required for histological diagnosis of acute cellular rejection and is an important contributor to establishing chronic lung allograft dysfunction, a common complication after lung transplant. Flexible bronchoscopy with bronchoalveolar lavage and transbronchial lung biopsy plays a key role in lung transplant graft assessment. In this article, we discuss the application of bronchoscopy in pediatric lung transplant evaluation including historical approaches, our experience, and future directions not only in bronchoscopy but also in the evolving pediatric lung transplantation field. Pediatric flexible bronchoscopy has become a vital modality for diagnosing lung transplant complications in children as well as assessing therapeutic responses. Herein, we review the value of flexible bronchoscopy in the management of children after lung transplant and discuss the application of novel techniques to improve care for this complex pediatric patient population and we provide a brief update about new diagnostic techniques applied in the growing lung transplantation field.

ECMO Bridge to Lung Transplant in Children with Idiopathic Pulmonary Arterial Hypertension.

Idiopathic pulmonary arterial hypertension (IPAH) represents an important clinical indication for lung transplant (LTx) in children. Recent trends show fewer children with IPAH are undergoing LTx nowadays compared to previous time periods, including those with most severe form of the disease. Using the UNOS Registry, we investigated if ECMO at the time of transplant impacts post-transplant survival in children with IPAH. A total of 74 LTx recipients while on ECMO at the time of transplant were identified (IPAH: N = 12). Children with IPAH who underwent LTx while on ECMO had shown comparable survival rates to those who were on ECMO for other conditions. This analysis provides encouraging results, supporting the potential expansion of LTx for this patient population. Given the low number of children undergoing LTx, we think there should be a consensus document to provide better guidance for referring and selecting the high-risk pediatric population with IPAH on ECMO for lung transplant.

Predicting Stroke For Pediatric Patients Supported With Ventricular Assist Devices:A PEDIMACS Report.

BACKGROUND: PEDIMACS provides detailed understanding on pediatric patients supported with ventricular assist devices (VADs). We sought to identify important variables affecting the incidence of stroke in pediatric VADs. METHODS: Between 2012-2022, 1,463 devices in 1,219 patients were reported to PEDIMACS s from 40 Centers in patients<19yrs at their first VAD implantation. Multiphase parametric hazard modeling was used to identify risk factors for stroke among all device types. RESULTS: Of the 1,219 patients, the most common devices were implantable continuous (472 [39%]), followed by paracorporeal pulsatile (342 [28%]), paracorporeal continuous (327 [27%]). Overall freedom from stroke at 6 months was higher in the recent era (2012-2016; 80.2% [77.1%-82.9%] vs 2017-2023; 87.9% [86.2%-89.4%], p=0.009). Implantable Continuous had the highest freedom from stroke at 3 (92.7% [91.1%-93.9%]) and 6 (91.1% [89.3%-92.6%]) months, followed by Paracorporeal Pulsatile (87.0% [84.8%-88.9%] and 82.8% [79.8%-85.5%]), and Paracoporeal Continuous (76.0% [71.8%-79.5%] and 69.5% [63.4%-74.8%]). Parametric modeling identified risk factors for stoke early post implant and later. Overall, and particularly for Paracorporal Pulsatile devices, early stroke risk has decreased in the most recent era (HR 5.01). Among Implantable Continuous devices, cardiogenic shock was the major risk factor. For patients<10kg, early hazard was only seen in previous era. For congentail patients, early hazard was seen in non-implantable device use and use of ECMO. CONCLUSIONS: Overall stroke rate has decreased from 20% to 15% at 6 months, with particular improvement among PP devices. Risk factor analyses offer insights for identification of higher stroke risk subsets and further management refinements.

The International Society for Heart and Lung Transplantation (ISHLT): 2024 infection definitions for durable and acute mechanical circulatory support devices.

Infections remain a significant concern in patients receiving mechanical circulatory support (MCS), encompassing both durable and acute devices. This consensus manuscript provides updated definitions for infections associated with durable MCS devices and new definitions for infections in acute MCS, integrating a comprehensive review of existing literature and collaborative discussions among multidisciplinary specialists. By establishing consensus definitions, we seek to enhance clinical care, facilitate consistent reporting in research studies, and ultimately improve outcomes for patients receiving MCS.

Multicenter Study on the Frequency of Low Bone Mineral Density in Young Women With Breast Cancer and Associated Factors.

INTRODUCTION: Young women with breast cancer (BC) may experience bone mineral density (BMD) loss secondary to cancer treatment effects on estrogen levels. Studies assessing BMD in BC patients have had a limited representation of young women. This multicenter retrospective study analyzed the frequency of low BMD and associated factors in this age group. METHODS: Women diagnosed with stage 0-III BC at ≤40 years, treated with chemotherapy and/or endocrine therapy between 2010 and 2020 at 5 Mexican BC referral centers were eligible. Demographic, clinical and treatment data were collected, as well as bone dual-energy X-ray absorptiometry (DEXA) results. Low BMD was defined as lumbar or femoral neck T-score < -1.0 or Z-score ≤ -2.0. RESULTS: A total of 1259 patients were included; median age at diagnosis was 36 years (21-40). Overall, 93% received chemotherapy and 65% endocrine therapy (tamoxifen was received at some point by 61%, aromatase inhibitors by 17%, and GnRH agonists/bilateral oophorectomy by 21%). DEXA scans were documented in 254 (20%), of which 163 (64%; 95% confidence interval [CI] 58%-70%) had a low BMD report. Low BMD was associated with receiving aromatase inhibitors (Odds ratio [OR] 1.92; 95% CI 1.13-3.24), and GnRH agonists/bilateral oophorectomy (OR 2.25; 95% CI 1.21-4.21). CONCLUSION: The suboptimal frequency of BMD monitoring observed displays an alarming disregard for bone health in young patients. Thus, a high proportion of women with low BMD are potentially being missed and precluded from the opportunity to receive timely interventions. Particular focus should be put on BMD monitoring among patients treated with aromatase inhibitors, GnRH agonists or bilateral oophorectomy.

Age-Dependent RGS5 Loss in Pericytes Induces Cardiac Dysfunction and Fibrosis.

BACKGROUND: Pericytes are capillary-associated mural cells involved in the maintenance and stability of the vascular network. Although aging is one of the main risk factors for cardiovascular disease, the consequences of aging on cardiac pericytes are unknown. METHODS: In this study, we have combined single-nucleus RNA sequencing and histological analysis to determine the effects of aging on cardiac pericytes. Furthermore, we have conducted in vivo and in vitro analysis of RGS5 (regulator of G-protein signaling 5) loss of function and finally have performed pericytes-fibroblasts coculture studies to understand the effect of RGS5 deletion in pericytes on the neighboring fibroblasts. RESULTS: Aging reduced the pericyte area and capillary coverage in the murine heart. Single-nucleus RNA sequencing analysis further revealed that the expression of Rgs5 was reduced in cardiac pericytes from aged mice. In vivo and in vitro studies showed that the deletion of RGS5 impaired cardiac function, induced fibrosis, and morphological changes in pericytes characterized by a profibrotic gene expression signature and the expression of different ECM (extracellular matrix) components and growth factors, for example, TGFB2 and PDGFB. Indeed, culturing fibroblasts with the supernatant of RGS5-deficient pericytes induced their activation as evidenced by the increased expression of αSMA (alpha smooth muscle actin) in a TGFß (transforming growth factor beta)2-dependent mechanism. CONCLUSIONS: Our results have identified RGS5 as a crucial regulator of pericyte function during cardiac aging. The deletion of RGS5 causes cardiac dysfunction and induces myocardial fibrosis, one of the hallmarks of cardiac aging.

Deep Learning for Automated Measurement of Total Cardiac Volume for Heart Transplantation Size Matching.

Total Cardiac Volume (TCV)-based size matching using Computed Tomography (CT) is a novel technique to compare donor and recipient heart size in pediatric heart transplant that may increase overall utilization of available grafts. TCV requires manual segmentation, which limits its widespread use due to time and specialized software and training needed for segmentation. This study aims to determine the accuracy of a Deep Learning (DL) approach using 3-dimensional Convolutional Neural Networks (3D-CNN) to calculate TCV, with the clinical aim of enabling fast and accurate TCV use at all transplant centers. Ground truth TCV was segmented on CT scans of subjects aged 0-30 years, identified retrospectively. Ground truth segmentation masks were used to train and test a custom 3D-CNN model consisting of a DenseNet architecture in combination with residual blocks of ResNet architecture. The model was trained on a cohort of 270 subjects and a validation cohort of 44 subjects (36 normal, 8 heart disease retained for model testing). The average Dice similarity coefficient of the validation cohort was 0.94 ± 0.03 (range 0.84-0.97). The mean absolute percent error of TCV estimation was 5.5%. There is no significant association between model accuracy and subject age, weight, or height. DL-TCV was on average more accurate for normal hearts than those listed for transplant (mean absolute percent error 4.5 ± 3.9 vs. 10.5 ± 8.5, p = 0.08). A deep learning-based 3D-CNN model can provide accurate automatic measurement of TCV from CT images. This initial study is limited as a single-center study, though future multicenter studies may enable generalizable and more accurate TCV measurement by inclusion of more diverse cardiac pathology and increasing the training data.

Transcatheter knocking of a stuck mechanical tricuspid valve.

Immobilisation of mechanical valve leaflets can be a life-threatening complication. In the acute setting, medical therapy can be attempted but is not always successful. We present the first described case of a patient with a mechanical tricuspid valve with recurrent leaflet immobilisation that was able to be mobilised using a transcatheter knocking technique.

Epidemiology of Postoperative Junctional Ectopic Tachycardia in Infants Undergoing Cardiac Surgery.

BACKGROUND: Junctional ectopic tachycardia (JET) complicates congenital heart surgery in 2% to 8.3% of cases. JET is associated with postoperative morbidity in single-center studies. We used the Pediatric Cardiac Critical Care Consortium data registry to provide a multicenter epidemiologic description of treated JET. METHODS: This is a retrospective study (February 2019-August 2022) of patients with treated JET. Inclusion criteria were (1) <12 months old at the index operation, and (2) treated for JET <72 hours after surgery. Diagnosis was defined by receiving treatment (pacing, cooling, and medications). A multilevel logistic regression analysis with hospital random effect identified JET risk factors. Impact of JET on outcomes was estimated by margins/attributable risk analysis using previous risk-adjustment models. RESULTS: Among 24,073 patients from 63 centers, 1436 (6.0%) were treated for JET with significant center variability (0% to 17.9%). Median time to onset was 3.4 hours, with 34% present on admission. Median duration was 2 days (interquartile range, 1-4 days). Tetralogy of Fallot, atrioventricular canal, and ventricular septal defect repair represented >50% of JET. Patient characteristics independently associated with JET included neonatal age, Asian race, cardiopulmonary bypass time, open sternum, and early postoperative inotropic agents. JET was associated with increased risk-adjusted durations of mechanical ventilation (incidence rate ratio, 1.6; 95% CI, 1.5-1.7) and intensive care unit length of stay (incidence rate ratio, 1.3; 95% CI, 1.2-1.3), but not mortality. CONCLUSIONS: JET is treated in 6% of patients with substantial center variability. JET contributes to increased use of postoperative resources. High center variability warrants further study to identify potential modifiable factors that could serve as targets for improvement efforts to ameliorate deleterious outcomes.

Socioeconomic Influences on Outcomes Following Congenital Heart Disease Surgery.

Associations between social determinants of health (SDOH) and adverse outcomes for children with congenital heart disease (CHD) are starting to be recognized; however, such links remain understudied. We examined the relationship between community-level material deprivation on mortality, readmission, and length of stay (LOS) for children undergoing surgery for CHD. We performed a retrospective cohort study of patients who underwent cardiac surgery at our institution from 2015 to 2018. A community-level deprivation index (DI), a marker of community material deprivation, was generated to contextualize the lived experience of children with CHD. Generalized mixed-effects models were used to assess links between the DI and outcomes of mortality, readmission, and LOS following cardiac surgery. The DI and components were scaled to provide mean differences for a one standard deviation (SD) increase in deprivation. We identified 1,187 unique patients with surgical admissions. The median LOS was 11 days, with an overall mortality rate of 4.6% and readmission rate of 7.6%. The DI ranged from 0.08 to 0.85 with a mean of 0.37 (SD 0.12). The DI was associated with increased LOS for patients with more complex heart disease (STAT 3, 4, and 5), which persisted after adjusting for factors that could prolong LOS (all p < 0.05). The DI approached but did not meet a significant association with mortality (p = 0.0528); it was not associated with readmission (p = 0.36). Community-level deprivation is associated with increased LOS for patients undergoing cardiac surgery. Future work to identify the specific health-related social needs contributing to LOS and identify targets for intervention is needed.

Unmasking the Impact of Oxygenator Induced Hypocapnia on Blood Lactate in Veno-Arterial Extracorporeal Membrane Oxygenation.

Extracorporeal membrane oxygenation (ECMO) is often associated with disturbances in acid/base status that can be triggered by the underlying pathology or the ECMO circuit itself. Extracorporeal membrane oxygenation is known to cause hypocapnia, but the impact of reduced partial pressure of carbon dioxide (pCO2) on biomarkers of tissue perfusion during veno-arterial (VA)-ECMO has not been evaluated. To study the impact of low pCO2 on perfusion indices in VA-ECMO, we placed Sprague-Dawley rats on an established VA-ECMO circuit using either an oxygen/carbon dioxide mixture (O2 95%, CO2 5%) or 100% O2 delivered through the oxygenator (n = 5 per cohort). Animals receiving 100% O2 developed a significant VA CO2 difference (pCO2 gap) and rising blood lactate levels that were inversely proportional to the decrease in pCO2 values. In contrast, pCO2 gap and lactate levels remained similar to pre-ECMO baseline levels in animals receiving the O2/CO2 mixture. More importantly, there was no significant difference in venous oxygen saturation (SvO2) between the two groups, suggesting that elevated blood lactate levels observed in the rats receiving 100% O2 were a response to oxygenator induced hypocapnia and alkaline pH rather than reduced perfusion or underlying tissue hypoxia. These findings have implications in clinical and experimental extracorporeal support contexts.

Effects of Spermine Synthase Deficiency in Mesenchymal Stromal Cells Are Rescued by Upstream Inhibition of Ornithine Decarboxylase.

Despite the well-known relevance of polyamines to many forms of life, little is known about how polyamines regulate osteogenesis and skeletal homeostasis. Here, we report a series of in vitro studies conducted with human-bone-marrow-derived pluripotent stromal cells (MSCs). First, we show that during osteogenic differentiation, mRNA levels of most polyamine-associated enzymes are relatively constant, except for the catabolic enzyme spermidine/spermine N1-acetyltransferase 1 (SAT1), which is strongly increased at both mRNA and protein levels. As a result, the intracellular spermidine to spermine ratio is significantly reduced during the early stages of osteoblastogenesis. Supplementation of cells with exogenous spermidine or spermine decreases matrix mineralization in a dose-dependent manner. Employing N-cyclohexyl-1,3-propanediamine (CDAP) to chemically inhibit spermine synthase (SMS), the enzyme catalyzing conversion of spermidine into spermine, also suppresses mineralization. Intriguingly, this reduced mineralization is rescued with DFMO, an inhibitor of the upstream polyamine enzyme ornithine decarboxylase (ODC1). Similarly, high concentrations of CDAP cause cytoplasmic vacuolization and alter mitochondrial function, which are also reversible with the addition of DFMO. Altogether, these studies suggest that excess polyamines, especially spermidine, negatively affect hydroxyapatite synthesis of primary MSCs, whereas inhibition of polyamine synthesis with DFMO rescues most, but not all of these defects. These findings are relevant for patients with Snyder-Robinson syndrome (SRS), as the presenting skeletal defects-associated with SMS deficiency-could potentially be ameliorated by treatment with DFMO.