Intravoxel incoherent motion as a surrogate marker of perfused vascular density in rat brain.

Intravoxel incoherent motion (IVIM) MRI has emerged as a valuable technique for the assessment of tissue characteristics and perfusion. However, there is limited knowledge about the relationship between IVIM-derived measures and changes at the level of the vascular network. In this study, we investigated the potential use of IVIM MRI as a noninvasive tool for measuring changes in cerebral vascular density. Variations in quantitative immunohistochemical measurements of the vascular density across different regions in the rat brain (cortex, corpus callosum, hippocampus, thalamus, and hypothalamus) were related to the pseudo-diffusion coefficient D* and the flowing blood fraction f in healthy Wistar rats. We assessed whether region-wise differences in the vascular density are reflected by variations in the IVIM measurements and found a significant positive relationship with the pseudo-diffusion coefficient (p < 0.05, ß = 0.24). The effect of cerebrovascular alterations, such as blood-brain barrier (BBB) disruption on the perfusion-related IVIM parameters, is not well understood. Therefore, we investigated the effect of BBB disruption on the IVIM measures in a rat model of metabolic and vascular comorbidities (ZSF1 obese rat) and assessed whether this affects the relationship between the cerebral vascular density and the noninvasive IVIM measurements. We observed increased vascular permeability without detecting any differences in diffusivity, suggesting that BBB leakage is present before changes in the tissue integrity. We observed no significant difference in the relationship between cerebral vascular density and the IVIM measurements in our model of comorbidities compared with healthy normotensive rats.

Pericyte loss initiates microvascular dysfunction in the development of diastolic dysfunction.

Aims: Microvascular dysfunction has been proposed to drive heart failure with preserved ejection fraction (HFpEF), but the initiating molecular and cellular events are largely unknown. Our objective was to determine when microvascular alterations in HFpEF begin, how they contribute to disease progression, and how pericyte dysfunction plays a role herein. Methods and results: Microvascular dysfunction, characterized by inflammatory activation, loss of junctional barrier function, and altered pericyte-endothelial crosstalk, was assessed with respect to the development of cardiac dysfunction, in the Zucker fatty and spontaneously hypertensive (ZSF1) obese rat model of HFpEF at three time points: 6, 14, and 21 weeks of age. Pericyte loss was the earliest and strongest microvascular change, occurring before prominent echocardiographic signs of diastolic dysfunction were present. Pericytes were shown to be less proliferative and had a disrupted morphology at 14 weeks in the obese ZSF1 animals, who also exhibited an increased capillary luminal diameter and disrupted endothelial junctions. Microvascular dysfunction was also studied in a mouse model of chronic reduction in capillary pericyte coverage (PDGF-Bret/ret), which spontaneously developed many aspects of diastolic dysfunction. Pericytes exposed to oxidative stress in vitro showed downregulation of cell cycle-associated pathways and induced a pro-inflammatory state in endothelial cells upon co-culture. Conclusion: We propose pericytes are important for maintaining endothelial cell function, where loss of pericytes enhances the reactivity of endothelial cells to inflammatory signals and promotes microvascular dysfunction, thereby accelerating the development of HFpEF.

Mortality Trends in Alzheimer's Disease in Mississippi, 2011-2021.

Alzheimer's disease is the sixth most common cause of death in the United States (U.S.), with one in three adults 65 years of age and older dying of the disease each year. Deaths from Alzheimer's have more than doubled between 2000 and 2019, killing more adults than both breast cancer and prostate cancer. In 2021, Alzheimer's disease resulted in 36 deaths per 100,000 in the U.S. In Mississippi, deaths from Alzheimer's have almost doubled between 2011 and 2021, resulting in 52.9 deaths per 100,000. Women have a higher mortality rate from Alzheimer's than men. Alzheimer's is a progressive disease that develops through seven stages. There are effective strategies to prevent the onset of Alzheimer's. METHODS: This paper reviews the risk factors, mortality trends, etiology, and prognosis of Alzheimer's in Mississippi with a focus on prevention. RESULTS: The southern diet with foods high in sugar and sodium, along with sedentary and poor lifestyle choices, increases mortality risk from Alzheimer's disease for women in Mississippi, specifically due to women over 65 having higher rates of obesity and hypertension. CONCLUSION: Understanding the epidemiology and risk factors of Alzheimer's in Mississippi will help inform communities, policies, and programs to prevent disease occurrence.

Mechanism of COVID-19-Induced Cardiac Damage from Patient, In Vitro and Animal Studies.

PURPOSE OF REVIEW: Though patient studies have been important for understanding the disease, research done in animals and cell culture complement our knowledge from patient data and provide insight into the mechanism of the disease. Understanding how COVID causes damage to the heart is essential to understanding possible long-term consequences. RECENT FINDINGS: COVID-19 is primarily a disease that attacks the lungs; however, it is known to have important consequences in many other tissues including the heart. Though myocarditis does occur in some patients, for most cases of cardiac damage, the injury arises from scarring either due to myocardial infarction or micro-infarction. The main focus is on how COVID affects blood flow through the coronaries. We review how endothelial activation leads to a hypercoagulative state in COVID-19. We also emphasize the effects that the cytokine storm can directly have on the regulation of coronary blood flow. Since the main two cell types that can be infected in the heart are pericytes and cardiomyocytes, we further describe the known effects on pericyte function and how that can further lead to microinfarcts within the heart. Though many of these effects are systemic, this review focuses on the consequences on cardiac tissue of this dysregulation and the role that it has in the formation of myocardial scarring.

Q-VAT: Quantitative Vascular Analysis Tool.

As our imaging capability increase, so does our need for appropriate image quantification tools. Quantitative Vascular Analysis Tool (Q-VAT) is an open-source software, written for Fiji (ImageJ), that perform automated analysis and quantification on large two-dimensional images of whole tissue sections. Importantly, it allows separation of the vessel measurement based on diameter, allowing the macro- and microvasculature to be quantified separately. To enable analysis of entire tissue sections on regular laboratory computers, the vascular network of large samples is analyzed in a tile-wise manner, significantly reducing labor and bypassing several limitations related to manual quantification. Double or triple-stained slides can be analyzed, with a quantification of the percentage of vessels where the staining's overlap. To demonstrate the versatility, we applied Q-VAT to obtain morphological read-outs of the vasculature network in microscopy images of whole-mount immuno-stained sections of various mouse tissues.

Clinical, genetic, epidemiologic, evolutionary, and functional delineation of TSPEAR-related autosomal recessive ectodermal dysplasia 14.

TSPEAR variants cause autosomal recessive ectodermal dysplasia (ARED) 14. The function of TSPEAR is unknown. The clinical features, the mutation spectrum, and the underlying mechanisms of ARED14 are poorly understood. Combining data from new and previously published individuals established that ARED14 is primarily characterized by dental anomalies such as conical tooth cusps and hypodontia, like those seen in individuals with WNT10A-related odontoonychodermal dysplasia. AlphaFold-predicted structure-based analysis showed that most of the pathogenic TSPEAR missense variants likely destabilize the ß-propeller of the protein. Analysis of 100000 Genomes Project (100KGP) data revealed multiple founder TSPEAR variants across different populations. Mutational and recombination clock analyses demonstrated that non-Finnish European founder variants likely originated around the end of the last ice age, a period of major climatic transition. Analysis of gnomAD data showed that the non-Finnish European population TSPEAR gene-carrier rate is ∼1/140, making it one of the commonest AREDs. Phylogenetic and AlphaFold structural analyses showed that TSPEAR is an ortholog of drosophila Closca, an extracellular matrix-dependent signaling regulator. We, therefore, hypothesized that TSPEAR could have a role in enamel knot, a structure that coordinates patterning of developing tooth cusps. Analysis of mouse single-cell RNA sequencing (scRNA-seq) data revealed highly restricted expression of Tspear in clusters representing enamel knots. A tspeara -/-;tspearb -/- double-knockout zebrafish model recapitulated the clinical features of ARED14 and fin regeneration abnormalities of wnt10a knockout fish, thus suggesting interaction between tspear and wnt10a. In summary, we provide insights into the role of TSPEAR in ectodermal development and the evolutionary history, epidemiology, mechanisms, and consequences of its loss of function variants.

Prevalence and Clinical Consequences of Multiple Pathogenic Variants in Dilated Cardiomyopathy.

BACKGROUND: Dilated cardiomyopathy (DCM) was considered a monogenetic disease that can be caused by over 60 genes. Evidence suggests that the combination of multiple pathogenic variants leads to greater disease severity and earlier onset. So far, not much is known about the prevalence and disease course of multiple pathogenic variants in patients with DCM. To gain insight into these knowledge gaps, we (1) systematically collected clinical information from a well-characterized DCM cohort and (2) created a mouse model. METHODS: Complete cardiac phenotyping and genotyping was performed in 685 patients with consecutive DCM. Compound heterozygous digenic (LMNA [lamin]/titin deletion A-band) with monogenic (LMNA/wild-type) and wild-type/wild-type mice were created and phenotypically followed over time. RESULTS: One hundred thirty-one likely pathogenic/pathogenic (LP/P) variants in robust DCM-associated genes were found in 685 patients with DCM (19.1%) genotyped for the robust genes. Three of the 131 patients had a second LP/P variant (2.3%). These 3 patients had a comparable disease onset, disease severity, and clinical course to patients with DCM with one LP/P. The LMNA/Titin deletion A-band mice had no functional differences compared with the LMNA/wild-type mice after 40 weeks of follow-up, although RNA-sequencing suggests increased cardiac stress and sarcomere insufficiency in the LMNA/Titin deletion A-band mice. CONCLUSIONS: In this study population, 2.3% of patients with DCM with one LP/P also have a second LP/P in a different gene. Although the second LP/P does not seem to influence the disease course of DCM in patients and mice, the finding of a second LP/P can be of importance to their relatives.

Computational modeling reveals inflammation-driven dilatation of the pulmonary autograft in aortic position.

The pulmonary autograft in the Ross procedure, where the aortic valve is replaced by the patient's own pulmonary valve, is prone to failure due to dilatation. This is likely caused by tissue degradation and maladaptation, triggered by the higher experienced mechanical loads in aortic position. In order to further grasp the causes of dilatation, this study presents a model for tissue growth and remodeling of the pulmonary autograft, using the homogenized constrained mixture theory and equations for immuno- and mechano-mediated mass turnover. The model outcomes, compared to experimental data from an animal model of the pulmonary autograft in aortic position, show that inflammation likely plays an important role in the mass turnover of the tissue constituents and therefore in the autograft dilatation over time. We show a better match and prediction of long-term outcomes assuming immuno-mediated mass turnover, and show that there is no linear correlation between the stress-state of the material and mass production. Therefore, not only mechanobiological homeostatic adaption should be taken into account in the development of growth and remodeling models for arterial tissue in similar applications, but also inflammatory processes.

Racial Disparities and Common Respiratory Infectious Diseases in Children of the United States: A Systematic Review and Meta-Analysis.

Due to the lack of sufficient data on the relationship between racial disparities and the occurrence of infectious respiratory diseases in children, the aim of this systematic review and meta-analysis is to evaluate the presence of racial gaps in the occurrence of respiratory infectious diseases in children. This study follows the PRISMA flow guidelines for systematic reviews and the standards of meta-analysis for 20 quantitative studies conducted from 2016 to 2022 including 2,184,407 participants. As evidenced from the review, in the U.S., racial disparities are present among children, with Hispanic and Black children carrying the burden of infectious respiratory disease occurrence. Several factors are contributory to these outcomes among Hispanic and Black children, including higher rates of poverty; higher rates of chronic conditions, such as asthma and obesity; and seeking care outside of the home. However, vaccinations can be used to reduce the risk of infection among Black and Hispanic children. Whether a child is very young or a teen, racial disparities are present in occurrence rates of infectious respiratory diseases, with the burden resting among minorities. Therefore, it is important for parents to be aware of the risk of infectious diseases and to be aware of resources, such as vaccines.

Evaluation of Microvascular Rarefaction in Vascular Cognitive Impairment and Heart Failure (CRUCIAL): Study Protocol for an Observational Study.

INTRODUCTION: Microvascular rarefaction, the functional reduction in perfused microvessels and structural reduction of microvascular density, seems to be an important mechanism in the pathophysiology of small blood vessel-related disorders including vascular cognitive impairment (VCI) due to cerebral small vessel disease and heart failure with preserved ejection fraction (HFpEF). Both diseases share common risk factors including hypertension, diabetes mellitus, obesity, and ageing; in turn, these comorbidities are associated with microvascular rarefaction. Our consortium aims to investigate novel non-invasive tools to quantify microvascular health and rarefaction in both organs, as well as surrogate biomarkers for cerebral and/or cardiac rarefaction (via sublingual capillary health, vascular density of the retina, and RNA content of circulating extracellular vesicles), and to determine whether microvascular density relates to disease severity. METHODS: The clinical research program of CRUCIAL consists of four observational cohort studies. We aim to recruit 75 VCI patients, 60 HFpEF patients, 60 patients with severe aortic stenosis (AS) undergoing surgical aortic valve replacement as a pressure overload HFpEF model, and 200 elderly participants with mixed comorbidities to serve as controls. Data collected will include medical history, physical examination, cognitive testing, advanced brain and cardiac MRI, ECG, echocardiography, sublingual capillary health, optical coherence tomography angiography (OCTa), extracellular vesicles RNA analysis, and myocardial remodelling-related serum biomarkers. The AS cohort undergoing surgery will also have myocardial biopsy for histological microvascular assessment. DISCUSSION: CRUCIAL will examine the pathophysiological role of microvascular rarefaction in VCI and HFpEF using advanced brain and cardiac MRI techniques. Furthermore, we will investigate surrogate biomarkers for non-invasive, faster, easier, and cheaper assessment of microvascular density since these are more likely to be disseminated into widespread clinical practice. If microvascular rarefaction is an early marker of developing small vessel diseases, then measuring rarefaction may allow preclinical diagnosis, with implications for screening, risk stratification, and prevention. Further knowledge of the relevance of microvascular rarefaction and its underlying mechanisms may provide new avenues for research and therapeutic targets.

SARS-CoV-2 infection causes prolonged cardiomyocyte swelling and inhibition of HIF1α translocation in an animal model COVID-19.

Recovered COVID-19 patients often display cardiac dysfunction, even after a mild infection. Most current histological results come from patients that are hospitalized and therefore represent more severe outcomes than most COVID-19 patients face. To overcome this limitation, we investigated the cardiac effects of SARS-CoV-2 infection in a hamster model. SARS-CoV-2 infected hamsters developed diastolic dysfunction after recovering from COVID-19. Histologically, increased cardiomyocyte size was present at the peak of viral load and remained at all time points investigated. As this increase is too rapid for hypertrophic remodeling, we found instead that the heart was oedemic. Moreover, cardiomyocyte swelling is associated with the presence of ischemia. Fibrin-rich microthrombi and pericyte loss were observed at the peak of viral load, resulting in increased HIF1α in cardiomyocytes. Surprisingly, SARS-CoV-2 infection inhibited the translocation of HIF1α to the nucleus both in hamster hearts, in cultured cardiomyocytes, as well as in an epithelial cell line. We propose that the observed diastolic dysfunction is the consequence of cardiac oedema, downstream of microvascular cardiac ischemia. Additionally, our data suggest that inhibition of HIF1α translocation could contribute to an exaggerated response upon SARS-CoV-2 infection.

Immunometabolic Mechanisms of Heart Failure with Preserved Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is increasing in prevalence worldwide, already accounting for at least half of all heart failure (HF). As most patients with HFpEF are obese with metabolic syndrome, metabolic stress has been implicated in syndrome pathogenesis. Recently, compelling evidence for bidirectional crosstalk between metabolic stress and chronic inflammation has emerged, and alterations in systemic and cardiac immune responses are held to participate in HFpEF pathophysiology. Indeed, based on both preclinical and clinical evidence, comorbidity-driven systemic inflammation, coupled with metabolic stress, have been implicated together in HFpEF pathogenesis. As metabolic alterations impact immune function(s) in HFpEF, major changes in immune cell metabolism are also recognized in HFpEF and in HFpEF-predisposing conditions. Both arms of immunity - innate and adaptive - are implicated in the cardiomyocyte response in HFpEF. Indeed, we submit that crosstalk among adipose tissue, the immune system, and the heart represents a critical component of HFpEF pathobiology. Here, we review recent evidence in support of immunometabolic mechanisms as drivers of HFpEF pathogenesis, discuss pivotal biological mechanisms underlying the syndrome, and highlight questions requiring additional inquiry.

AAV9-mediated functional screening for cardioprotective cytokines in Coxsackievirus-B3-induced myocarditis.

Viral myocarditis (VM) is an important cause of heart failure (HF) in children and adults. However, the molecular determinants involved in cardiac inflammation and cardiomyocyte necrosis remain poorly characterized, and cardioprotective molecules are currently missing. Here, we applied an in vivo method based on the functional selection (FunSel) of cardioprotective factors using AAV vectors for the unbiased identification of novel immunomodulatory molecules in a Coxsackievirus B3 (CVB3)-induced myocarditis mouse model. Two consecutive rounds of in vivo FunSel using an expression library of 60 cytokines were sufficient to identify five cardioprotective factors (IL9, IL3, IL4, IL13, IL15). The screening also revealed three cytokines (IL18, IL17b, and CCL11) that were counter-selected and likely to exert a detrimental effect. The pooled overexpression of the five most enriched cytokines using AAV9 vectors decreased inflammation and reduced cardiac dilatation, persisting at 1 month after treatment. Individual overexpression of IL9, the top ranking in our functional selection, markedly reduced cardiac inflammation and injury, concomitant with an increase of anti-inflammatory Th2-cells and a reduction of pro-inflammatory Th17- and Th22-cells at 14 days post-infection. AAV9-mediated FunSel cardiac screening identified IL9 and other four cytokines (IL3, IL4, IL13, and IL15) as cardioprotective factors in CVB3-induced VM in mice.

Understanding Pulmonary Autograft Remodeling After the Ross Procedure: Stick to the Facts.

The Ross, or pulmonary autograft, procedure presents a fascinating mechanobiological scenario. Due to the common embryological origin of the aortic and pulmonary root, the conotruncus, several authors have hypothesized that a pulmonary autograft has the innate potential to remodel into an aortic phenotype once exposed to systemic conditions. Most of our understanding of pulmonary autograft mechanobiology stems from the remodeling observed in the arterial wall, rather than the valve, simply because there have been many opportunities to study the walls of dilated autografts explanted at reoperation. While previous histological studies provided important clues on autograft adaptation, a comprehensive understanding of its determinants and underlying mechanisms is needed so that the Ross procedure can become a widely accepted aortic valve substitute in select patients. It is clear that protecting the autograft during the early adaptation phase is crucial to avoid initiating a sequence of pathological remodeling. External support in the freestanding Ross procedure should aim to prevent dilatation while simultaneously promoting remodeling, rather than preventing dilatation at the cost of vascular atrophy. To define the optimal mechanical properties and geometry for external support, the ideal conditions for autograft remodeling and the timeline of mechanical adaptation must be determined. We aimed to rigorously review pulmonary autograft remodeling after the Ross procedure. Starting from the developmental, microstructural and biomechanical differences between the pulmonary artery and aorta, we review autograft mechanobiology in relation to distinct clinical failure mechanisms while aiming to identify unmet clinical needs, gaps in current knowledge and areas for further research. By correlating clinical and experimental observations of autograft remodeling with established principles in cardiovascular mechanobiology, we aim to present an up-to-date overview of all factors involved in extracellular matrix remodeling, their interactions and potential underlying molecular mechanisms.

Organ-Specific Endothelial Cell Differentiation and Impact of Microenvironmental Cues on Endothelial Heterogeneity.

Endothelial cells throughout the body are heterogeneous, and this is tightly linked to the specific functions of organs and tissues. Heterogeneity is already determined from development onwards and ranges from arterial/venous specification to microvascular fate determination in organ-specific differentiation. Acknowledging the different phenotypes of endothelial cells and the implications of this diversity is key for the development of more specialized tissue engineering and vascular repair approaches. However, although novel technologies in transcriptomics and proteomics are facilitating the unraveling of vascular bed-specific endothelial cell signatures, still much research is based on the use of insufficiently specialized endothelial cells. Endothelial cells are not only heterogeneous, but their specialized phenotypes are also dynamic and adapt to changes in their microenvironment. During the last decades, strong collaborations between molecular biology, mechanobiology, and computational disciplines have led to a better understanding of how endothelial cells are modulated by their mechanical and biochemical contexts. Yet, because of the use of insufficiently specialized endothelial cells, there is still a huge lack of knowledge in how tissue-specific biomechanical factors determine organ-specific phenotypes. With this review, we want to put the focus on how organ-specific endothelial cell signatures are determined from development onwards and conditioned by their microenvironments during adulthood. We discuss the latest research performed on endothelial cells, pointing out the important implications of mimicking tissue-specific biomechanical cues in culture.

Personalised virtual gene panels reduce interpretation workload and maintain diagnostic rates of proband-only clinical exome sequencing for rare disorders.

PURPOSE: The increased adoption of genomic strategies in the clinic makes it imperative for diagnostic laboratories to improve the efficiency of variant interpretation. Clinical exome sequencing (CES) is becoming a valuable diagnostic tool, capable of meeting the diagnostic demand imposed by the vast array of different rare monogenic disorders. We have assessed a clinician-led and phenotype-based approach for virtual gene panel generation for analysis of targeted CES in patients with rare disease in a single institution. METHODS: Retrospective survey of 400 consecutive cases presumed by clinicians to have rare monogenic disorders, referred on singleton basis for targeted CES. We evaluated diagnostic yield and variant workload to characterise the usefulness of a clinician-led approach for generation of virtual gene panels that can incorporate up to three different phenotype-driven gene selection methods. RESULTS: Abnormalities of the nervous system (54.5%), including intellectual disability, head and neck (19%), skeletal system (16%), ear (15%) and eye (15%) were the most common clinical features reported in referrals. Combined phenotype-driven strategies for virtual gene panel generation were used in 57% of cases. On average, 7.3 variants (median=5) per case were retained for clinical interpretation. The overall diagnostic rate of proband-only CES using personalised phenotype-driven virtual gene panels was 24%. CONCLUSIONS: Our results show that personalised virtual gene panels are a cost-effective approach for variant analysis of CES, maintaining diagnostic yield and optimising the use of resources for clinical genomic sequencing in the clinic.

Association and Risk Factors for Obstructive Sleep Apnea and Cardiovascular Diseases: A Systematic Review.

Obstructive sleep apnea (OSA) is a serious, potentially life-threatening condition. Epidemiologic studies show that sleep apnea increases cardiovascular diseases risk factors including hypertension, obesity, and diabetes mellitus. OSA is also responsible for serious illnesses such as congestive heart failure, stroke, arrhythmias, and bronchial asthma. The aim of this systematic review is to evaluate evidence for the association between OSA and cardiovascular disease morbidities and identify risk factors for the conditions. In a review of 34 studies conducted in 28 countries with a sample of 37,599 people, several comorbidities were identified in patients with severe OSA-these were: heart disease, stroke, kidney disease, asthma, COPD, acute heart failure, chronic heart failure, hyperlipidemia, thyroid disease, cerebral infarct or embolism, myocardial infarction, and psychological comorbidities including stress and depression. Important risk factors contributing to OSA included: age > 35 years; BMI ≥ 25 kg/m2; alcoholism; higher Epworth sleepiness scale (ESS); mean apnea duration; oxygen desaturation index (ODI); and nocturnal oxygen desaturation (NOD). Severe OSA (AHI ≥ 30) was significantly associated with excessive daytime sleepiness and oxygen desaturation index. The risk of OSA and associated disease morbidities can be reduced by controlling overweight/obesity, alcoholism, smoking, hypertension, diabetes mellitus, and hyperlipidemia.

The enpp4 ectonucleotidase regulates kidney patterning signalling networks in Xenopus embryos.

The enpp ectonucleotidases regulate lipidic and purinergic signalling pathways by controlling the extracellular concentrations of purines and bioactive lipids. Although both pathways are key regulators of kidney physiology and linked to human renal pathologies, their roles during nephrogenesis remain poorly understood. We previously showed that the pronephros was a major site of enpp expression and now demonstrate an unsuspected role for the conserved vertebrate enpp4 protein during kidney formation in Xenopus. Enpp4 over-expression results in ectopic renal tissues and, on rare occasion, complete mini-duplication of the entire kidney. Enpp4 is required and sufficient for pronephric markers expression and regulates the expression of RA, Notch and Wnt pathway members. Enpp4 is a membrane protein that binds, without hydrolyzing, phosphatidylserine and its effects are mediated by the receptor s1pr5, although not via the generation of S1P. Finally, we propose a novel and non-catalytic mechanism by which lipidic signalling regulates nephrogenesis.

Expanding the phenotypic spectrum of pathogenic variants in the PRRT2 gene: bilateral papilledema and abducens nerve palsies secondary to pseudotumor cerebri syndrome.

An 8-year-old girl with known pathogenic variant in the PRRT2 gene causing paroxysmal kinesigenic dyskinesia with infantile convulsions presented with bilateral papilledema and abducens nerve palsy, which was subsequently confirmed to be pseudotumor cerebri syndrome (PTCS). She was treated with acetazolamide and recovered baseline vision, with some residual papilledema. PTCS is not confirmed to be associated with pathogenic variants in the PRRT2 gene; however, this case in conjunction with a previously reported case of PTCS and unilateral abducens nerve palsy in a patient with PRRT2 variants, raises the possibility that PTCS is part of the phenotypic spectrum rather than being a coincidental occurrence.

Back to the root: a large animal model of the Ross procedure.

The excellent clinical outcomes of the Ross procedure and previous histological studies suggest that the pulmonary autograft has the potential to offer young patients a permanent solution to aortic valve disease. We aim to study the early mechanobiological adaptation of the autograft. To this end, we have reviewed relevant existing animal models, including the canine models which enabled Donald N Ross to perform the first Ross procedure in a patient in 1967. Two research groups recently evaluated the isolated effect of systemic pressures on pulmonary arterial tissue in an ovine model of a pulmonary artery interposition graft in the descending aorta. While this model is ideal to study the artery's biological response and the effect of external support, it does not recreate the complex environment of the aortic root. The freestanding Ross procedure has been performed in pigs and sheep before. These studies offered valuable insights into leaflet growth and histological remodeling, yet may be less relevant to adults undergoing the Ross procedure, as pronounced autograft dilatation was achieved by using small, rapidly growing animals. Therefore, a large animal model remains needed to determine the ideal conditions and surgical technique to ensure long-term autograft remodeling and valve function. We set out to develop an ovine model of the Ross procedure performed as a freestanding root replacement, acknowledging that the sheep's specific anatomy and the setting of an animal laboratory would mandate several modifications in surgical strategy. This article describes the development, surgical technique and early outcomes of our animal model while highlighting opportunities for further research.