Genetics and mechanisms of thoracic aortic disease

Aortic disease has many forms including aortic aneurysm and dissection, aortic coarctation or abnormalities in aortic function, such as loss of aortic distensibility. Genetic analysis in humans is one of the most important experimental approaches in uncovering disease mechanisms, but the relative infrequency of thoracic aortic disease compared with other cardiovascular conditions such as coronary artery disease has hindered large-scale identification of genetic associations. In the past decade, advances in machine learning technology coupled with large imaging datasets from biobank repositories have facilitated a rapid expansion in our capacity to measure and genotype aortic traits, resulting in the identification of dozens of genetic associations. In this Review, we describe the history of technological advances in genetic discovery and explain how newer technologies such as deep learning can rapidly define aortic traits at scale. Furthermore, we integrate novel genetic observations provided by these advances into our current biological understanding of thoracic aortic disease and describe how these new findings can contribute to strategies to prevent and treat aortic disease.

Virtual Simulation of Intra-operative Decision-Making for Open Abdominal Aortic Aneurysm Repair: A Mixed Methods Analysis

OBJECTIVE

To create and pilot test a novel open abdominal aortic aneurysm (AAA) repair virtual simulation focused on intraoperative decision-making. To identify if the simulation replicated real-time intra-operative decision-making and discover how learners' respond to this type of simulation.

DESIGN

An explanatory sequential mixed methods study. We developed a step-by-step outline of major intra-operative decision points within a standard open AAA repair. Perioperative and intraoperative decision-making trees were developed and coded into an online virtual simulation. The simulation was piloted. Quantitative data was collected from the simulation platform. We then performed a qualitative thematic analysis on feedback from interviewed participants.

SETTING

Four academic general and vascular surgical training programs across the US.

PARTICIPANTS

Seventeen vascular and general surgery trainees and 6 vascular surgery faculty.

RESULTS

Participants spent on average 27 minutes (range: 8-45 minutes) interacting with the interface. 93% of participants reported feeling they were making real intraoperative decisions. 85% said it added to their knowledge base. 96% requested additional simulations. 22 interviews were completed: 241 primary codes were collapsed into 21 parent codes, and 6 emerging themes identified. Themes included the benefit of how (1) "Virtual Learning Could Standardize the Training Experience"; how (2) "Dealing with the Unexpected" as a trainee is an important part of surgical education growth, and that this (3) "Choose Your Own Adventure" virtual format simulates this intraoperative growth experience. Participants requested a (4) "Looping Feature Feedback Diagram" for future simulation iterations and highlighted that (5) "Fancier is Not Necessarily More Educational." Finally, many trainees wondered about (6) "The Attending Impact" from the simulation: if faculty would notice a difference between trainees who did vs did not utilize the simulation for case preparation.

CONCLUSIONS

Operative simulation training should focus on both technical skills and intra-operative decision-making, particularly "dealing with the unexpected." The learners' responses indicate that a low-fidelity, scalable, virtual platform can effectively deliver knowledge and allow for intra-operative decision-making practice in a remote learning environment.

Female Sex Portends Worse Long-Term Survival after Open Type I-III Thoracoabdominal Aneurysm Repair

BACKGROUND

Although outcomes after infrarenal abdominal aortic aneurysm surgery are worse in females, sex-specific differences in outcomes after open thoracoabdominal aortic aneurysm (TAAA) repair are less clear. The goal of this study was to identify sex-based disparities in short- and long-term outcomes after open type I-III TAAA surgery.

METHODS

All open type I-III TAAA repairs performed from 1987 to 2015 were evaluated using an institutional database. Charts were retrospectively evaluated for perioperative outcomes: major adverse events (MAEs), in-hospital death, and long-term survival. Univariate analysis was performed using the Fisher's exact test for categorical variables and the Wilcoxon rank-sum test for continuous variables. Logistic regression was used for in-hospital end points; survival analyses were performed with Cox proportional hazards modeling and Kaplan-Meier techniques. Sensitivity analyses were performed for relevant multivariable models, one with ruptures removed and another evaluating only repairs performed before 2006 to account for any selection bias due to wider use of complex endovascular technology.

RESULTS

Five-hundred sixteen patients underwent open type I-III TAAA repair during the study period. Females accounted for 54.3% (n = 280) of the cohort. Women were older, less likely to have a chronic dissection etiology, more likely to present with a symptomatic/ruptured lesion, and had a lower admission creatinine than men. Perioperative death occurred in 23 men (9.8%) and 19 women (6.8%) (P = 0.26); 133 women (47.3%) and 116 men (49.2%) suffered an MAE (P = 0.72). Multivariable analyses revealed no sex-based difference in perioperative death (Female sex adjusted odds ratio (AOR): 0.72, 95% confidence interval (CI): 0.4-1.4, P = 0.34) or MAE (AOR: 1.0 CI: 0.7-1.5, P = 0.82). Unadjusted survival at five years was 50% for women and 67% for men (log-rank P < 0.001). Female sex was an independent predictor of decreased survival (hazard ratio (HR): 1.5 95% CI: 1.2-1.9, P = 0.001) when adjusted for age, aneurysm extent, creatinine, chronic obstructive pulmonary disease, and ruptures. After removing all ruptures, female sex remained nonpredictive of perioperative death (AOR: 1.1, 95% CI 0.5-2.5, P = 0.75) or MAE (AOR: 1.2, CI: 0.8-1.9, P = 0.31) and predictive of decreased long-term survival (HR: 1.5, 95% CI: 1.2-2.0, P = 0.001).

CONCLUSIONS

Those undergoing open type I-III TAAA repair have similar rates of perioperative mortality and MAEs, regardless of sex. However, female sex is an independent risk factor for decreased long-term survival.

Longitudinal trajectories of everyday function by diagnostic status

Generalized linear mixed models were used to examine longitudinal trajectories of everyday functional limitations by diagnostic stability/progression. Older adults (N = 384) were followed an average 3.6 years; participants were grouped by diagnosis at study baseline and last follow-up (normal cognition, Mild Cognitive Impairment, or dementia at each time point). At study baseline there were clear group differences; most notably among participants initially characterized as cognitively normal, those who developed Mild Cognitive Impairment or dementia over follow-up already demonstrated greater functional impairment compared with those who remained cognitively normal. Change in functional impairment progressed slowly in the early disease groups, but showed an accelerated worsening in those converting to dementia.

The molecular biology of prostate cancer morbidity and mortality: Accelerated death from ejaculate poisoning?

The molecular biology of host-tumor interactions unique to human prostate cancer that cause patient morbidity are poorly understood despite the prevalence of this neoplasm. Little is known fundamentally about prostate-specific exocrine gene products secreted by metastatic prostate carcinoma cells at metastatic sites that cause diffuse bone pain, immunosuppression, anemia, cachexia, and other clinical signs of advanced prostate cancer. Growing evidence supports the presence of androgen-regulated exocrine gene products as independent mediators of prostate cancer morbidity. The experimental and clinical implications of a hypothesis that prostate-specific exocrine genes cause patient morbidity are discussed.

Induction of endothelin-1 expression by glucose: an effect of protein kinase C activation

Enhanced actions or levels of endothelin-1 (ET-1), a potent vasoconstrictor, have been associated with decreased blood flow in the retina and peripheral nerves of diabetic animals and may be related to the development of pathologies in these tissues. Hyperglycemia has been postulated to increase ET-1 secretion in endothelial cells. We have characterized the mechanism by which elevation of glucose is increasing ET-1 mRNA expression in capillary bovine retinal endothelial cells (BREC) and bovine retinal pericytes (BRPC). Elevation of glucose, but not mannitol, from 5.5 to 25 mmol/l for 3 days increased membranous protein kinase C (PKC) activities and ET-1 mRNA in parallel levels by 2-fold in BREC and BRPC. These effects were reversed by decreasing glucose levels to 5.5 mmol/l for an additional 2 days. Glucose-induced ET-1 overexpression was inhibited by a general PKC inhibitor, GF109203X, and a mitogen-activated protein kinase kinase inhibitor, PD98059, but not by wortmannin, a phosphatidylinositol 3-kinase inhibitor. By immunoblot analysis, PKC-beta2 and -delta isoforms in BREC were significantly increased relative to other isoforms in the membranous fractions when glucose level was increased. Overexpression of PKC-beta1 and -delta isoforms but not PKC-zeta isoform by adenovirus vectors containing the respective cDNA enhanced in parallel PKC activities, proteins, and basal and glucose-induced ET-1 mRNA expression by at least 2-fold. These results showed that enhanced ET-1 expression induced by hyperglycemia in diabetes is partly due to activation of PKC-beta and -delta isoforms, suggesting that inhibition of these PKC isoforms may prevent early changes in diabetic retinopathy and neuropathy.

Induction of endothelin-1 expression by glucose: an effect of protein kinase C activation

Enhanced actions or levels of endothelin-1 (ET-1), a potent vasoconstrictor, have been associated with decreased blood flow in the retina and peripheral nerves of diabetic animals and may be related to the development of pathologies in these tissues. Hyperglycemia has been postulated to increase ET-1 secretion in endothelial cells. We have characterized the mechanism by which elevation of glucose is increasing ET-1 mRNA expression in capillary bovine retinal endothelial cells (BREC) and bovine retinal pericytes (BRPC). Elevation of glucose, but not mannitol, from 5.5 to 25 mmol/l for 3 days increased membranous protein kinase C (PKC) activities and ET-1 mRNA in parallel levels by 2-fold in BREC and BRPC. These effects were reversed by decreasing glucose levels to 5.5 mmol/l for an additional 2 days. Glucose-induced ET-1 overexpression was inhibited by a general PKC inhibitor, GF109203X, and a mitogen-activated protein kinase kinase inhibitor, PD98059, but not by wortmannin, a phosphatidylinositol 3-kinase inhibitor. By immunoblot analysis, PKC-beta2 and -delta isoforms in BREC were significantly increased relative to other isoforms in the membranous fractions when glucose level was increased. Overexpression of PKC-beta1 and -delta isoforms but not PKC-zeta isoform by adenovirus vectors containing the respective cDNA enhanced in parallel PKC activities, proteins, and basal and glucose-induced ET-1 mRNA expression by at least 2-fold. These results showed that enhanced ET-1 expression induced by hyperglycemia in diabetes is partly due to activation of PKC-beta and -delta isoforms, suggesting that inhibition of these PKC isoforms may prevent early changes in diabetic retinopathy and neuropathy.

Identification of PKC-isoform-specific biological actions using pharmacological approaches

The protein kinase C (PKC) family consists of at least 12 isoforms that possess distinct differences in structure, substrate requirement, expression and localization. To date, identification of the physiological function of individual PKC isoforms has been restricted by the availability of few agents that inhibit or activate the isoforms with specificity. More recent approaches that are used to modulate PKC isoforms include oligonucleotide antisense technology, and peptide fragments to either inhibit or promote translocation of PKC isoforms to specific anchoring proteins. In this review, several currently available inhibitors and activators of PKC that display varying degrees of selectivity for the PKC isoforms will be discussed.

Inhibition of Epstein-Barr virus replication by a novel L-nucleoside, 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil

A novel L-nucleoside analog, 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil (L-FMAU), was found to be a potent and selective inhibitor of Epstein-Barr virus (EBV) replication. The decrease in the amount of viral production was concentration dependent with a 90% inhibitory concentration of approximately 5 muM. Upon removal of the drug from treated cells, virus production resumed in 21 days. Metabolism studies indicated that L-FMAU could be converted to its mono-,di- and triphosphate metabolites in both EBV producing and non-producing cells than in EBV non-producing cells. The mechanism of selectivity of L-FMAU against EBV producing cells. However, the amount of L-FMAU nucleotides formed was three times larger in EBV producing cells than in EBV non-producing cells. The mechanism of selectivity of L-FMAU against EBV does not appear to be due solely to the preferential phosphorylation of L-FMAU in EBV producing cells. The triphosphate of L-FMAU could not be utilized as a substrate by EBV DNA polymerase or the human DNA polymerases alpha, beta, gamma, or delta. Therefore, the incorporation of L-FMAU residues into viral DNA may not be the mechanism of antiviral activity. This compound appears to have a mechanism of action different from that of any other antiherpes virus nucleoside analogs. In addition, L-FMAU has very low cytotoxicity with 50% inhibition of cell growth occurring at a concentration of 1mM. Given the potent inhibitory activity of this compound against EBV and its inability to be incorporated into cellular DNA, L-FMAU analogs should be explored as a new class of anti-EBV agents.

Sustained cytokine production and immunophenotypic changes in human neuroblastoma cell lines transduced with a human gamma interferon vector

The majority of human neuroblastomas express low to undetectable levels of major histocompatibility complex (MHC) class I and II antigens (MHC-I and -II). We studied the effects of gamma interferon (gamma-IFN) transduction on expression of these antigens in six human neuroblastoma cell lines with and without genomic amplification of the N-myc oncogene. All six were stably transduced with an MoMLV-based gamma-IFN retroviral vector (DAh gamma-IFN). G418-resistant cells were assayed for MHC-I, MHC-II, B7-1, and neuroblastoma-associated antigen expression, as well as for gamma-IFN levels in cell culture supernatants. Sustained gamma-IFN production, 2 to > 1000 units/10(6) cells/d, was attained for five of six transduced cell lines and persisted for up to 9 months. This resulted in marked upregulation of MHC-I and MHC-II expression in LA-N-1, LA-N-6, and CHLA-127 cells and moderate upregulation in SK-N-Fi and SK-N-AS cells. One cell line (LA-N-1) had marked induction of MHC-I and MHC-II despite marginal levels of gamma-IFN production. Expression of CD28 ligand B7-1 (as determined by BB1 antibody) remained unchanged in all gamma-IFN-transduced cell lines tested. Expression of several neuroblastoma-associated antigens (NKH1A, 126-4, HSAN 1.2, HNK, 459, and 390) was upregulated in some of the gamma-IFN-transduced cell lines. These results demonstrate that preparation of gamma-IFN expressing neuroblastoma cells for immunotherapeutic purposes is feasible and that gamma-IFN transduction results in phenotypic changes that may improve immunogenicity of human neuroblastoma cells.