Significance of isolated postoperative atrial fibrillation in thoracic aortic aneurysm repair.

OBJECTIVE: Although postoperative atrial fibrillation has been shown to be associated with worse survival after thoracic aortic surgery, its effect on outcomes independently from other postoperative complications is not well understood. METHODS: This is a single-center retrospective study of patients who underwent open thoracic aortic aneurysm repair between March 2005 and March 2021. Postoperative atrial fibrillation was defined as new-onset atrial fibrillation that developed during the index hospital stay. Patients with preoperative atrial fibrillation were excluded. Postoperative major complications included reoperation for bleeding, respiratory failure, acute renal failure, and stroke. Variables associated with postoperative atrial fibrillation were analyzed with multivariable regression. Survival of patients without major complications was compared between patients without atrial fibrillation and patients with postoperative atrial fibrillation after propensity score matching for baseline and intraoperative characteristics. RESULTS: Of 1454 patients, 520 (35.8%) were observed to have postoperative atrial fibrillation. Patients with postoperative atrial fibrillation had a higher rate of postoperative major complications than those without atrial fibrillation (20.2% vs 12.2%, P < .001). Ten-year survival was 82.0% in patients with postoperative atrial fibrillation and 87.0% in patients without atrial fibrillation (P = .008). In the cohort of patients without complications, 10-year survival was similar between patients with and without postoperative atrial fibrillation after propensity score matching (83.6% vs 83.8%, P = .75). CONCLUSIONS: Postoperative atrial fibrillation is common after open proximal thoracic aortic aneurysm repair. Although development of major postoperative complications is associated with postoperative atrial fibrillation and decreased long-term survival, isolated postoperative atrial fibrillation does not appear to influence long-term survival.

Cell-type-specific regulation of APOE and CLU levels in human neurons by the Alzheimer's disease risk gene SORL1.

SORL1 is implicated in the pathogenesis of Alzheimer's disease (AD) through genetic studies. To interrogate the roles of SORL1 in human brain cells, SORL1-null induced pluripotent stem cells (iPSCs) were differentiated to neuron, astrocyte, microglial, and endothelial cell fates. Loss of SORL1 leads to alterations in both overlapping and distinct pathways across cell types, with the greatest effects in neurons and astrocytes. SORL1 loss induces a neuron-specific reduction in apolipoprotein E (APOE) and clusterin (CLU) and altered lipid profiles. Analyses of iPSCs derived from a large cohort reveal a neuron-specific association between SORL1, APOE, and CLU levels, a finding validated in postmortem brain. Enhancement of retromer-mediated trafficking rescues tau phenotypes observed in SORL1-null neurons but does not rescue APOE levels. Pathway analyses implicate transforming growth factor ß (TGF-ß)/SMAD signaling in SORL1 function, and modulating SMAD signaling in neurons alters APOE RNA levels in a SORL1-dependent manner. Taken together, these data provide a mechanistic link between strong genetic risk factors for AD.

Valve-sparing root replacement versus composite valve graft root replacement: Analysis of more than 1500 patients from 2 aortic centers.

OBJECTIVES: The long-term outcomes comparing valve-sparing root replacement, composite valve graft with bioprosthesis, and mechanical prosthesis have yet to be explored. We investigated the long-term survival and reintervention rates after 1 of 3 major aortic root replacements in patients with tricuspid aortic valves and patients with bicuspid aortic valves. METHODS: A total of 1507 patients underwent valve-sparing root replacement (n = 700), composite valve graft with bioprosthesis (n = 703), or composite valve graft with mechanical prosthesis (n = 104) between 2004 and 2021 in 2 aortic centers, excluding those with dissection, endocarditis, stenosis, or prior aortic valve surgery. End points included mortality over time and cumulative incidence of aortic valve/proximal aorta reintervention. Multivariable Cox regression compared adjusted 12-year survival. Fine and Gray competing risk regression compared the risk and cumulative incidence of reintervention. Propensity score-matched subgroup analysis balanced the 2 major groups (composite valve graft with bioprosthesis and valve-sparing root replacement), and landmark analysis isolated outcomes beginning 4 years postoperatively. RESULTS: On multivariable analysis, both composite valve graft with bioprosthesis (hazard ratio, 1.91, P = .001) and composite valve graft with mechanical prosthesis (hazard ratio, 2.62, P = .005) showed increased 12-year mortality risk versus valve-sparing root replacement. After propensity score matching, valve-sparing root replacement displayed improved 12-year survival versus composite valve graft with bioprosthesis (87.9% vs 78.8%, P = .033). Adjusted 12-year reintervention risk in patients receiving composite valve graft with bioprosthesis or composite valve graft with mechanical prosthesis versus valve-sparing root replacement was similar (composite valve graft with bioprosthesis subdistribution hazard ratio, 1.49, P = .170) (composite valve graft with mechanical prosthesis subdistribution hazard ratio, 0.28, P = .110), with a cumulative incidence of 7% in valve-sparing root replacement, 17% in composite valve graft with bioprosthesis, and 2% in composite valve graft with mechanical prosthesis (P = .420). Landmark analysis at 4 years showed an increased incidence of late reintervention in composite valve graft with bioprosthesis versus valve-sparing root replacement (P = .008). CONCLUSIONS: Valve-sparing root replacement, composite valve graft with mechanical prosthesis, and composite valve graft with bioprosthesis demonstrated excellent 12-year survival, with valve-sparing root replacement associated with better survival. All 3 groups have low incidence of reintervention, with valve-sparing root replacement showing decreased late postoperative need for reintervention compared with composite valve graft with bioprosthesis.

Cell-type-specific regulation of APOE levels in human neurons by the Alzheimer's disease risk gene SORL1.

SORL1 is strongly implicated in the pathogenesis of Alzheimer's disease (AD) through human genetic studies that point to an association of reduced SORL1 levels with higher risk for AD. To interrogate the role(s) of SORL1 in human brain cells, SORL1 null iPSCs were generated, followed by differentiation to neuron, astrocyte, microglia, and endothelial cell fates. Loss of SORL1 led to alterations in both overlapping and distinct pathways across cell types, with the greatest effects in neurons and astrocytes. Intriguingly, SORL1 loss led to a dramatic neuron-specific reduction in APOE levels. Further, analyses of iPSCs derived from a human aging cohort revealed a neuron-specific linear correlation between SORL1 and APOE RNA and protein levels, a finding validated in human post-mortem brain. Pathway analysis implicated intracellular transport pathways and TGF- ß/SMAD signaling in the function of SORL1 in neurons. In accord, enhancement of retromer-mediated trafficking and autophagy rescued elevated phospho-tau observed in SORL1 null neurons but did not rescue APOE levels, suggesting that these phenotypes are separable. Stimulation and inhibition of SMAD signaling modulated APOE RNA levels in a SORL1-dependent manner. These studies provide a mechanistic link between two of the strongest genetic risk factors for AD.

Cell type-selective targeted delivery of a recombinant lysosomal enzyme for enzyme therapies.

Lysosomal diseases are a class of genetic disorders predominantly caused by loss of lysosomal hydrolases, leading to lysosomal and cellular dysfunction. Enzyme replacement therapy (ERT), where recombinant enzyme is given intravenously, internalized by cells, and trafficked to the lysosome, has been applied to treat several lysosomal diseases. However, current ERT regimens do not correct disease phenotypes in all affected organs because the biodistribution of enzyme uptake does not match that of the affected cells that require the enzyme. We present here targeted ERT, an approach that utilizes antibody-enzyme fusion proteins to target the enzyme to specific cell types. The antibody moiety recognizes transmembrane proteins involved in lysosomal trafficking and that are also preferentially expressed in those cells most affected in disease. Using Pompe disease (PD) as an example, we show that targeted ERT is superior to ERT in treating the skeletal muscle phenotypes of PD mice both as a protein replacement therapeutic and as a gene therapy.

Detailed Clinical and Psychological Phenotype of the X-linked HNRNPH2-Related Neurodevelopmental Disorder.

OBJECTIVE: To expand the clinical phenotype of the X-linked HNRNPH2-related neurodevelopmental disorder in 33 individuals. METHODS: Participants were diagnosed with pathogenic or likely pathogenic variants in HNRNPH2 using American College of Medical Genetics and Genomics/Association of Molecular Pathology criteria, largely identified via clinical exome sequencing. Genetic reports were reviewed. Clinical data were collected by retrospective chart review and caregiver report including standardized parent report measures. RESULTS: We expand our clinical characterization of HNRNPH2-related disorders to include 33 individuals, aged 2-38 years, both females and males, with 11 different de novo missense variants, most within the nuclear localization signal. The major features of the phenotype include developmental delay/intellectual disability, severe language impairment, motor problems, growth, and musculoskeletal disturbances. Minor features include dysmorphic features, epilepsy, neuropsychiatric diagnoses such as autism spectrum disorder, and cortical visual impairment. Although rare, we report early stroke and premature death with this condition. CONCLUSIONS: The spectrum of X-linked HNRNPH2-related disorders continues to expand as the allelic spectrum and identification of affected males increases.

RNA nanotechnology for computer design and in vivo computation.

Molecular-scale computing has been explored since 1989 owing to the foreseeable limitation of Moore's law for silicon-based computation devices. With the potential of massive parallelism, low energy consumption and capability of working in vivo, molecular-scale computing promises a new computational paradigm. Inspired by the concepts from the electronic computer, DNA computing has realized basic Boolean functions and has progressed into multi-layered circuits. Recently, RNA nanotechnology has emerged as an alternative approach. Owing to the newly discovered thermodynamic stability of a special RNA motif (Shu et al. 2011 Nat. Nanotechnol. 6, 658-667 (doi:10.1038/nnano.2011.105)), RNA nanoparticles are emerging as another promising medium for nanodevice and nanomedicine as well as molecular-scale computing. Like DNA, RNA sequences can be designed to form desired secondary structures in a straightforward manner, but RNA is structurally more versatile and more thermodynamically stable owing to its non-canonical base-pairing, tertiary interactions and base-stacking property. A 90-nucleotide RNA can exhibit 49° nanostructures, and its loops and tertiary architecture can serve as a mounting dovetail that eliminates the need for external linking dowels. Its enzymatic and fluorogenic activity creates diversity in computational design. Varieties of small RNA can work cooperatively, synergistically or antagonistically to carry out computational logic circuits. The riboswitch and enzymatic ribozyme activities and its special in vivo attributes offer a great potential for in vivo computation. Unique features in transcription, termination, self-assembly, self-processing and acid resistance enable in vivo production of RNA nanoparticles that harbour various regulators for intracellular manipulation. With all these advantages, RNA computation is promising, but it is still in its infancy. Many challenges still exist. Collaborations between RNA nanotechnologists and computer scientists are necessary to advance this nascent technology.