Nanoparticle Delivery of Immunostimulatory Alu RNA for Cancer Immunotherapy.

It was recently found that patients with relapsing remitting multiple sclerosis exhibit widespread loss of adenosine-to-inosine (A-to-I) RNA editing, which contributes to the accumulation of immunostimulatory double-stranded Alu RNA in circulating leukocytes and an attendant increase in levels of proinflammatory cytokines (e.g., type I IFNs). A specific Alu RNA (i.e., AluJb RNA) was implicated in activating multiple RNA-sensing pathways and found to be a potent innate immune agonist. Here, we have performed a bioinformatic analysis of A-to-I RNA editing in human melanoma samples and determined that pre-therapy levels of A-to-I RNA editing negatively correlate with survival times, suggesting that an accumulation of endogenous double-stranded Alu RNA might contribute to cancer patient survival. Furthermore, we demonstrated that immunostimulatory Alu RNA can be leveraged pharmacologically for cancer immunotherapy. AluJb RNA was in vitro transcribed and then formulated with endosome-destabilizing polymer nanoparticles to improve intracellular delivery of the RNA and enable activation of RNA-sensing pathways. AluJb RNA/polymer complexes (i.e., Alu-NPs) were engineered to form colloidally stable nanoparticles that exhibited immunostimulatory activity in vitro and in vivo. Finally, the therapeutic potential of Alu-NPs for the treatment of cancer was demonstrated by attenuated tumor growth and prolonged survival in the B16.F10 murine melanoma tumor model. Thus, these data collectively implicate intratumoral Alu RNA as a potentiator of antitumor innate immunity and identify AluJb RNA as a novel nucleic acid immunotherapeutic for cancer. Significance: Loss of A-to-I editing leads to accumulation of unedited Alu RNAs that activate innate immunity via RNA-sensing pattern recognition receptors. When packaged into endosome-releasing polymer nanoparticles, AluJB RNA becomes highly immunostimulatory and can be used pharmacologically to inhibit tumor growth in mouse melanoma models. These findings identify Alu RNAs as a new class of nucleic acid innate immune agonists for cancer immunotherapy.

Reduced RNA adenosine-to-inosine editing in hippocampus vasculature associated with Alzheimer's disease.

Alzheimer's disease is the most common form of dementia and recent studies identify a type 1 interferon response in Alzheimer's disease possibly driving neuro-inflammation and other Alzheimer's disease pathologies. Loss of adenosine-to-inosine editing of endogenous Alu RNAs results in accumulation of Alu double-stranded RNAs, activation of double-stranded RNA sensors, and induction of interferon and nuclear factor kappa B regulated genes. Here, we investigated if changes in adenosine-to-inosine editing were associated with presence of Alzheimer's disease in total prefrontal cortex, total hippocampus, cortex vasculature and hippocampus vasculature using available RNA sequencing files. We found similar levels of Alu RNA adenosine-to-inosine editing in cortex and cortex vasculature from individuals with Alzheimer's disease or normal cognition at the time of death and brain donation. We found modest and substantial loss of adenosine-to-inosine editing in hippocampus and hippocampus vasculature, respectively, in Alzheimer's disease relative to normal cognition and increased expression of interferon and nuclear factor kappa B regulated genes in hippocampus. Unedited Alu RNAs as found in Alzheimer's disease hippocampus vasculature were potent innate immune activators while edited Alu RNAs as found in normal cognition hippocampus vasculature were weak innate immune activators. Taken together, our results support a model whereby loss of Alu RNA adenosine-to-inosine editing in hippocampus results in innate immune activation that may contribute to Alzheimer's disease pathogenesis.

Paradoxical response to chest wall loading predicts a favorable mechanical response to reduction in tidal volume or PEEP.

BACKGROUND: Chest wall loading has been shown to paradoxically improve respiratory system compliance (CRS) in patients with moderate to severe acute respiratory distress syndrome (ARDS). The most likely, albeit unconfirmed, mechanism is relief of end-tidal overdistension in 'baby lungs' of low-capacity. The purpose of this study was to define how small changes of tidal volume (VT) and positive end-expiratory pressure (PEEP) affect CRS (and its associated airway pressures) in patients with ARDS who demonstrate a paradoxical response to chest wall loading. We hypothesized that small reductions of VT or PEEP would alleviate overdistension and favorably affect CRS and conversely, that small increases of VT or PEEP would worsen CRS. METHODS: Prospective, multi-center physiologic study of seventeen patients with moderate to severe ARDS who demonstrated paradoxical responses to chest wall loading. All patients received mechanical ventilation in volume control mode and were passively ventilated. Airway pressures were measured before and after decreasing/increasing VT by 1 ml/kg predicted body weight and decreasing/increasing PEEP by 2.5 cmH2O. RESULTS: Decreasing either VT or PEEP improved CRS in all patients. Driving pressure (DP) decreased by a mean of 4.9 cmH2O (supine) and by 4.3 cmH2O (prone) after decreasing VT, and by a mean of 2.9 cmH2O (supine) and 2.2 cmH2O (prone) after decreasing PEEP. CRS increased by a mean of 3.1 ml/cmH2O (supine) and by 2.5 ml/cmH2O (prone) after decreasing VT. CRS increased by a mean of 5.2 ml/cmH2O (supine) and 3.6 ml/cmH2O (prone) after decreasing PEEP (P < 0.01 for all). Small increments of either VT or PEEP worsened CRS in the majority of patients. CONCLUSION: Patients with a paradoxical response to chest wall loading demonstrate uniform improvement in both DP and CRS following a reduction in either VT or PEEP, findings in keeping with prior evidence suggesting its presence is a sign of end-tidal overdistension. The presence of 'paradox' should prompt re-evaluation of modifiable determinants of end-tidal overdistension, including VT, PEEP, and body position.

Alu RNA Structural Features Modulate Immune Cell Activation and A-to-I Editing of Alu RNAs Is Diminished in Human Inflammatory Bowel Disease.

Alu retrotransposons belong to the class of short interspersed nuclear elements (SINEs). Alu RNA is abundant in cells and its repetitive structure forms double-stranded RNAs (dsRNA) that activate dsRNA sensors and trigger innate immune responses with significant pathological consequences. Mechanisms to prevent innate immune activation include deamination of adenosines to inosines in dsRNAs, referred to as A-to-I editing, degradation of Alu RNAs by endoribonucleases, and sequestration of Alu RNAs by RNA binding proteins. We have previously demonstrated that widespread loss of Alu RNA A-to-I editing is associated with diverse human diseases including viral (COVID-19, influenza) and autoimmune diseases (multiple sclerosis). Here we demonstrate loss of A-to-I editing in leukocytes is also associated with inflammatory bowel diseases. Our structure-function analysis demonstrates that ability to activate innate immune responses resides in the left arm of Alu RNA, requires a 5'-PPP, RIG-I is the major Alu dsRNA sensor, and A-to-I editing disrupts both structure and function. Further, edited Alu RNAs inhibit activity of unedited Alu RNAs. Altering Alu RNA nucleotide sequence increases biological activity. Two classes of Alu RNAs exist, one class stimulates both IRF and NF-kB transcriptional activity and a second class only stimulates IRF transcriptional activity. Thus, Alu RNAs play important roles in human disease but may also have therapeutic potential.

Reduced A-to-I editing of endogenous Alu RNAs in lung after SARS-CoV-2 infection.

Due to potential severity of disease caused by SARS-CoV-2 infection, it is critical to understand both mechanisms of viral pathogenesis as well as diversity of host responses to infection. Reduced A-to-I editing of endogenous double-stranded RNAs (dsRNAs), as a result of inactivating mutations in ADAR, produces one form of Aicardi-Goutières Syndrome, with an immune response similar to an anti-viral response. By analyzing whole genome RNA sequencing data, we find reduced levels of A-to-I editing of endogenous Alu RNAs in normal human lung cells after infection by SARS-CoV-2 as well as in lung biopsies from patients with SARS-CoV-2 infections. Unedited Alu RNAs, as seen after infection, induce IRF and NF-kB transcriptional responses and downstream target genes, while edited Alu RNAs as seen in the absence of infection, fail to activate these transcriptional responses. Thus, decreased A-to-I editing may represent an important host response to SARS-CoV-2 infection.

Cutting Edge: Reduced Adenosine-to-Inosine Editing of Endogenous Alu RNAs in Severe COVID-19 Disease.

Severe COVID-19 disease is associated with elevated inflammatory responses. One form of Aicardi-Goutières syndrome caused by inactivating mutations in ADAR results in reduced adenosine-to-inosine (A-to-I) editing of endogenous dsRNAs, induction of IFNs, IFN-stimulated genes, other inflammatory mediators, morbidity, and mortality. Alu elements, ∼10% of the human genome, are the most common A-to-I-editing sites. Using leukocyte whole-genome RNA-sequencing data, we found reduced A-to-I editing of Alu dsRNAs in patients with severe COVID-19 disease. Dendritic cells infected with COVID-19 also exhibit reduced A-to-I editing of Alu dsRNAs. Unedited Alu dsRNAs, but not edited Alu dsRNAs, are potent inducers of IRF and NF-κB transcriptional responses, IL6, IL8, and IFN-stimulated genes. Thus, decreased A-to-I editing that may lead to accumulation of unedited Alu dsRNAs and increased inflammatory responses is associated with severe COVID-19 disease.

Adenosine-to-Inosine RNA Editing of Alu Double-Stranded (ds)RNAs Is Markedly Decreased in Multiple Sclerosis and Unedited Alu dsRNAs Are Potent Activators of Proinflammatory Transcriptional Responses.

Sensors that detect dsRNA stimulate IFN responses as a defense against viral infection. IFN responses are also well documented in a variety of human autoimmune diseases, including relapsing-remitting multiple sclerosis (MS), in which increased IFN responses result from increased levels of double-stranded endogenous Alu RNAs. Mechanisms underlying increases in double-stranded Alu RNAs in MS are obscure. We find widespread loss of adenosine-to-inosine editing of Alu RNAs in MS. Unedited Alu RNAs are potent activators of both IFN and NF-κB responses via the dsRNA sensors, RIG-I, and TLR3. Minor editing of highly active Alu elements abrogates the ability to activate both transcriptional responses. Thus, adenosine-to-inosine editing may also represent an important defense against autoimmune diseases such as MS.

Interchromosomal Translocations as a Means to Map Chromosome Territories in Breast Cancer.

The genome-wide identification of mutated genes is an important advance in our understanding of tumor biology, but several fundamental questions remain open. How do these genes act together to promote cancer development and, a related question, how are they spatially arranged in the nucleus to allow coordinated expression? We examined the nuclear topography of mutated genes in breast cancer and their relation to chromosome territories (CTs). We performed a literature review and analyzed 1 type of mutation, interchromosomal translocations, in 1546 primary breast cancers to infer the spatial arrangement of chromosomes. The cosegregation of all observed fusion genes was used to create a matrix of genome-wide CT contacts and develop a tentative CT map of breast cancer. Regression analysis was performed to determine the association between CTs and all types of mutations. Chromosomes 17, 11, 8, and 1 had the majority of interchromosomal fusions and are presumably clustered in the nuclear center, whereas chromosomes 22, 21, X, and 18 had the lowest number of contacts, likely reflecting a more peripheral position. Regression analysis revealed that there was no significant association between chromosome length indicated by the number of base pairs per chromosome and the number of total (inter- and intrachromosomal) translocations, point mutations, or copy number aberrations (CNAs). The gene density of chromosomes (genes/Mb) was significantly correlated with total translocations (P = .02), but not with point mutations P = .19 and CNAs P = .62. Finally, the association of the 3 genetic alterations with the CT map deduced from the interchromosomal fusions was significant, ie, total translocations P = 7 × 10-11, point mutations P = .01, CNAs P = .002. In conclusion, we developed a tentative CT map and observed a spatial association with genetic alterations in breast cancer.

Genomic-Epidemiologic Evidence That Estrogens Promote Breast Cancer Development.

Background: Estrogens are a prime risk factor for breast cancer, yet their causal relation to tumor formation remains uncertain. A recent study of 560 breast cancers identified 82 genes with 916 point mutations as drivers in the genesis of this malignancy. Because estrogens play a major role in breast cancer development and are also known to regulate the expression of numerous genes, we hypothesize that the 82 driver genes are likely to be influenced by estrogens, such as 17ß-estradiol (E2), and the estrogen receptor ESR1 (ERα). Because different types of tumors are characterized by unique sets of cancer driver genes, we also argue that the fraction of driver genes regulated by E2-ESR1 is lower in malignancies not associated with estrogens, e.g., acute myeloid leukemia (AML).Methods: We performed a literature search of each driver gene to determine its E2-ESR1 regulation.Results: Fifty-three of the 82 driver genes (64.6%) identified in breast cancers showed evidence of E2-ESR1 regulation. In contrast, only 19 of 54 mutated driver genes (35.2%) identified in AML were linked to E2-ESR1. Among the 916 driver mutations found in breast cancers, 813 (88.8%) were linked to E2-ESR1 compared with 2,046 of 3,833 in AML (53.4%).Conclusions: Risk assessment revealed that mutations in estrogen-regulated genes are much more likely to be associated with elevated breast cancer risk, while mutations in unregulated genes are more likely to be associated with AML.Impact: These results increase the plausibility that estrogens promote breast cancer development. Cancer Epidemiol Biomarkers Prev; 27(8); 899-907. ©2018 AACR.

Geometric ring annuloplasty as an adjunct to aortic valve repair: clinical investigation of the HAART 300 device.

OBJECTIVES: This study assessed the safety and efficacy of an internal geometric annuloplasty ring in a regulatory trial of aortic valve reconstruction (ClinicalTrials.gov Identifier: NCT01400841). METHODS: Sixty-five patients with predominant moderate-to-severe trileaflet aortic insufficiency (AI) underwent aortic valve repair with an average age of 63 ± 13 years (mean ± SD). All had initial implantation of an internal aortic annuloplasty ring to correct annular dilatation and facilitate leaflet reconstruction. Leaflet plication was performed for prolapse in 80% of patients, and more complex leaflet procedures, usually employing autologous pericardium, were required in 22%. Ascending aortic and/or root aneurysms were replaced in 62%. RESULTS: Follow-up was for a maximum of 3 years and a mean of 2 years. No in-hospital operative mortalities, major complications or early or late valve-related events occurred. The annular diameter before repair was 26.5 ± 2.3 mm, and the average ring diameter used was 21.5 ± 1.6 mm. The preoperative AI grade (0-4) was 2.9 ± 0.8 and improved after repair to 0.6 ± 0.7 (P < 0.0001), as did the NYHA class. The mean valve gradient was 8.6 ± 4.3 mmHg, and at 3 years, the Kaplan-Meier survival rate was 95%, with no valve-related mortality. Over the 3 years, aortic valve replacement was required in 7 patients (10.8%) for reasons usually related to surgical technique. Most repair failures occurred early, and results stabilized after 6 months. No structural complications of the rings were observed. CONCLUSIONS: Geometric ring annuloplasty was a safe and effective adjunct to aortic valve repair. Initial correction of annular dilatation seemed to facilitate overall reconstruction. Because most early repair failures were technical, increasing experience with geometric ring annuloplasty for aortic valve reconstruction has the potential to standardize and improve outcomes.

A geometric model of the normal human aortic root and design of a fully anatomic aortic root graft.

OBJECTIVE: Available aortic root grafts generally flare outward in the sinus region, and this feature improves procedural ease. However, no current device is based on normal aortic root geometry, and a fully anatomic aortic root graft could further facilitate valve-sparing root operations. METHODS: To develop a model of the normal human aortic root, high-resolution computed tomographic angiogram images from 11 normal human aortas generated high-density x, y, z coordinates of valve and root structures in Mathematica. Three-dimensional least-squares regression analyses assessed geometry of the aortic valve and root. Shapes and dimensions were quantified, and minor variations in geometry were simplified during graft design. RESULTS: Normal aortic valve and root geometry was represented as three leaflet-sinus general ellipsoids nested within a cylindrical aorta. Sinotubular junction diameter was 5 mm larger than the valve base-with a slight funnel-shaped outward commissural flare but cylindrical geometry above the midvalve. The valve base was elliptical, but the midvalve and the sinotubular junction were circular above the midvalve level. Commissural locations on the base circumference were equidistant. On the basis of average three-dimensional geometry, a root graft was designed for root remodeling procedures-to be used with an internal geometric annuloplasty ring of the same design. CONCLUSIONS: An aortic root graft was designed on the basis of mathematical analyses of computed tomographic angiogram images. The design incorporated three anatomic sinuses, commissural symmetry, and compatibility with geometric ring annuloplasty. The anatomic graft may prove useful for restoring aortic root geometry toward normal during aortic valve and root surgery.

Techniques of autologous pericardial leaflet replacement for aortic valve reconstruction.

Glutaraldehyde-fixed autologous pericardium rarely calcifies or retracts, and it is a useful substitute for cardiac valve leaflets. Current understanding of aortic valve geometry provides good models for aortic leaflet design, and pericardial leaflet construction is illustrated in this article for bicuspid and tri-leaflet valves. Outcomes have been characterized by low valve-related complication rates, and results of recent series are encouraging. Perhaps sufficient data are available to consider autologous pericardial leaflet replacement in highly selected younger patients with irreparable leaflets and contraindications to warfarin.

Hemodynamic outcomes of geometric ring annuloplasty for aortic valve repair: a 4-center pilot trial.

OBJECTIVES: A geometric annuloplasty ring could improve efficacy and stability of aortic valve repair. Toward this goal, a 1-piece 3-dimensional titanium annuloplasty ring with Dacron covering was developed and tested successfully in animals. The purpose of this study was to define hemodynamic outcomes with this device used as the annuloplasty component of human aortic valve repair. METHODS: In a 4-center pilot trial with informed consent, 16 patients underwent aortic valve repair for aortic insufficiency, with the annuloplasty device sutured into the annulus beneath the leaflets. Preoperative annular diameter averaged 26.5 ± 2.0 (mean ± standard deviation) mm, and average ring size was 22.3 ± 1.2 mm. After annuloplasty, leaflet defects were easy to identify, and 14 of 16 patients (88%) required leaflet plication and/or autologous pericardial reconstruction for leaflet defects. Three patients had ascending aortic replacement, and 2 had remodeling root replacement. One had ultrasonic leaflet decalcification and another tricuspid valve annuloplasty. Follow-up data were from site-specific studies at the 6-month postoperative time point. RESULTS: There were no in-hospital mortalities or major complications. Preoperative aortic insufficiency grade (0-4 scale) was 3.6 ± 1.0 and fell to 1.0 ± 0.8 at 6 months (P < .0001). New York Heart Association class fell from 2.5 ± 0.5 to 1.1 ± 0.3 (P < .0001). Postrepair valve area was 2.7 ± 0.2 cm(2), and 6-month mean systolic gradient was 11.3 ± 3.3 mm Hg. Left ventricular end-diastolic diameter and ejection fraction both normalized (both P < .0001). CONCLUSIONS: Geometric ring annuloplasty facilitated aortic valve repair, allowing more precise reconstruction of leaflet defects. Aortic insufficiency reduction and systolic gradients were excellent, and expansion of valve reconstruction into broader categories of aortic valve disease seems indicated.

Early results of a novel technique for ring-reinforced aortic valve and root restoration.

OBJECTIVES: Surgery for aortic root aneurysm without valve stenosis is increasingly being transformed from the Bentall procedure to valve-sparing aortic root remodelling or reimplantation. In this report, a new repair option is explored, with full functional 'restoration' of the aortic root complex using a geometric annuloplasty ring, leaflet repair, and sinus/ascending aortic replacement with a Valsalva graft. METHODS: The geometric annuloplasty ring restores elliptical annular shape and size in patients with tri-leaflet aortic insufficiency (AI). The ring mounts the three valve commissures on 10° outwardly flaring posts, and facilitates required leaflet procedures. In clinical application, the device has been effective in achieving stable AI reduction with low valve gradients. In this report, 6 patients with aortic root aneurysms and moderate/severe AI were managed with valve repair using the annuloplasty device and leaflet reconstruction, and then concomitant sinus and ascending aortic graft replacement with coronary implantation. RESULTS: In the 6 initial root aneurysm patients, there were no in-hospital mortalities, procedural conversions, or valve-related complications. Preoperative AI grade was 2-4 and fell to 0-1 postoperatively. Post-repair mean systolic gradients ranged from 7 to 12 mmHg, and all patients had stable intermediate-term valve function. CONCLUSIONS: Aortic root restoration using a geometric annuloplasty ring and Valsalva graft may be the most physiological method of aortic valve repair and root replacement. Even with severe leaflet derangements, valve sparing can be achieved with good competence and potentially stable long-term results. This technique could assist in extending valve sparing into most categories of aortic root disease. CLINICAL TRIALS: Patients were managed as part of a Phase I (ClinicalTrials.gov Identifier: NCT01400841), supported by BioStable Science and Engineering (BSE), Austin, TX, USA; www.biostable-s-e.com.

A refined hemispheric model of normal human aortic valve and root geometry.

BACKGROUND: Better understanding of aortic root geometry could improve diagnosis and reconstruction of pathologic aortic valves. In this study, a previous model of hemispheric aortic valve leaflets nested within a cylindrical aorta was refined in humans with normal aortic valves. METHODS: Using 1-mm axial slices, high-resolution computed tomographic angiograms from 10 normal aortic roots were used to generate high-density X-, Y-, and Z-coordinates of valve structures using Mathematica software. Three-dimensional least squares regression analyses of leaflet and sinus coordinates were employed to compare multiple geometric models of aortic valve and root geometry. Shapes and dimensions of all root structures were evaluated and compared. RESULTS: Aortic valve geometry was roughly hemispherical, but the valve base was elliptical (minor-major diameter ratio = .66). Dimensional fits of the leaflet-sinus complexes also were better using ellipsoidal geometry, with taller leaflets than predicted by hemispheres. The commissure between the left and noncoronary cusps was located uniformly at the posterior junction of the base minor diameter and circumference, with the center of the right coronary cusp opposite. The subcommissural post areas flared outward by 5° to 10°, and the volume of the right coronary leaflet-sinus complex was 12.4% and 10.7% larger than the noncoronary cusps and left cusps, respectively. CONCLUSIONS: The normal human aortic valve is an elliptical structure, and ellipsoidal refinements improve representation of leaflet geometry. The left and noncoronary cusps commissure is located posteriorly; the right coronary cusp is located anteriorly. This model could be useful in quantifying pathologic geometry and in engineering devices for aortic valve reconstruction.

Techniques of autologous pericardial leaflet replacement for bicuspid aortic valve endocarditis.

BACKGROUND AND AIM OF THE STUDY: Valvular endocarditis constitutes high-risk cardiac surgery, with worse early and late results than for other disorders. Current data suggest that repairing endocarditis valves may produce better outcomes, but bicuspid endocarditis has been difficult to repair. Given the excellent early and late results now being achieved with autologous pericardial leaflet replacement, the present study involved complete pericardial leaflet replacement, a procedure that could facilitate the autologous reconstruction of bicuspid valves. METHODS: Four patients with endocarditis of bicuspid valves, each exhibiting variations in anatomy and presentation, were included. All four patients had received antibiotics preoperatively and had been converted to culture-negative. All had infection of the fused leaflet, and three had retention of their normal non-fused leaflets for the repair. Using glutaraldehyde-fixed autologous pericardium, all damaged leaflets were fully replaced, employing bileaflet repairs in three patients and a trileaflet repair in one patient. One patient required both bicuspid leaflets to be replaced with two autologous pericardial leaflets because of concurrent calcification. RESULTS: All four patients recovered uneventfully, and had fully competent valves with minimal gradients. All were subsequently managed without anticoagulation, and during up to two years of follow up the reconstructed valves functioned normally. None of the patients experienced any valve-related complications. CONCLUSION: In an anatomic spectrum of bicuspid endocarditis, the preservation of normal leaflets and complete replacement of damaged leaflets with autologous pericardium has provided an excellent reparative solution. This method could allow a stable autologous reconstruction in the majority of patients, although more experience and follow up will be necessary to fully validate the procedure.

Early results after implantation of a new geometric annuloplasty ring for aortic valve repair.

BACKGROUND: Aortic valve repair is associated with fewer long-term valve-related complications as compared with valve replacement, and repair is being performed increasingly. A current problem is the lack of a geometric annuloplasty ring to facilitate reconstruction. This paper describes the first clinical application of such a device designed to permanently restore physiologic annular size and geometry during aortic valve repair. METHODS: Based on mathematical studies of human cadaver valves, as well as computed tomography angiographic analyses of awake patients with normal valves, a three-dimensional annuloplasty ring has been developed, consisting of low-profile, one-piece titanium construction and Dacron cloth covering. The ring design incorporates 2:3 elliptical base geometry and 10-degree outwardly flaring subcommissural posts. RESULTS: Appropriately sized rings were implanted in 5 patients with severe aortic insufficiency due to annular dilation and anatomic leaflet defects. The rings restored annular geometry and facilitated leaflet repairs in all patients. Each recovered excellent valve function with minimal residual leak. All patients convalesced uneventfully, were discharged within 7 days after surgery, and continue with stable valve function as long as 6 months after implantation. CONCLUSIONS: Initial clinical application of a geometric aortic annuloplasty ring was associated with excellent device performance and perhaps better repairs. Further clinical series and patient follow-up should identify potential benefits of the device, including improved applicability and stability of aortic valve repair.

Estrogen metabolism and exposure in a genotypic-phenotypic model for breast cancer risk prediction.

BACKGROUND: Current models of breast cancer risk prediction do not directly reflect mammary estrogen metabolism or genetic variability in exposure to carcinogenic estrogen metabolites. METHODS: We developed a model that simulates the kinetic effect of genetic variants of the enzymes CYP1A1, CYP1B1, and COMT on the production of the main carcinogenic estrogen metabolite, 4-hydroxyestradiol (4-OHE(2)), expressed as area under the curve metric (4-OHE(2)-AUC). The model also incorporates phenotypic factors (age, body mass index, hormone replacement therapy, oral contraceptives, and family history), which plausibly influence estrogen metabolism and the production of 4-OHE(2). We applied the model to two independent, population-based breast cancer case-control groups, the German GENICA study (967 cases, 971 controls) and the Nashville Breast Cohort (NBC; 465 cases, 885 controls). RESULTS: In the GENICA study, premenopausal women at the 90th percentile of 4-OHE(2)-AUC among control subjects had a risk of breast cancer that was 2.30 times that of women at the 10th control 4-OHE(2)-AUC percentile (95% CI: 1.7-3.2, P = 2.9 × 10(-7)). This relative risk was 1.89 (95% CI: 1.5-2.4, P = 2.2 × 10(-8)) in postmenopausal women. In the NBC, this relative risk in postmenopausal women was 1.81 (95% CI: 1.3-2.6, P = 7.6 × 10(-4)), which increased to 1.83 (95% CI: 1.4-2.3, P = 9.5 × 10(-7)) when a history of proliferative breast disease was included in the model. CONCLUSIONS: The model combines genotypic and phenotypic factors involved in carcinogenic estrogen metabolite production and cumulative estrogen exposure to predict breast cancer risk. IMPACT: The estrogen carcinogenesis-based model has the potential to provide personalized risk estimates.

Increased sensitivity to apoptosis induced by methotrexate is mediated by JNK.

OBJECTIVE: Low-dose methotrexate (MTX) is an effective therapy for rheumatoid arthritis (RA), yet its mechanism of action is incompletely understood. The aim of this study was to explore the induction of apoptosis by MTX. METHODS: Flow cytometry was performed to assess changes in the levels of intracellular proteins, reactive oxygen species (ROS), and apoptosis. Quantitative polymerase chain reaction was performed to assess changes in the transcript levels of select target genes in response to MTX. RESULTS: MTX did not directly induce apoptosis but rather "primed" cells for markedly increased sensitivity to apoptosis via either mitochondrial or death receptor pathways, by a JNK-dependent mechanism. Increased sensitivity to apoptosis was mediated, at least in part, by MTX-dependent production of ROS, JNK activation, and JNK-dependent induction of genes whose protein products promote apoptosis. Supplementation with tetrahydrobiopterin blocked these MTX-induced effects. Patients with RA who were receiving low-dose MTX therapy expressed elevated levels of the JNK target gene, jun. CONCLUSION: Our results support a model whereby MTX inhibits reduction of dihydrobiopterin to tetrahydrobiopterin, resulting in increased production of ROS, increased JNK activity, and increased sensitivity to apoptosis. The finding of increased jun levels in patients with RA receiving low-dose MTX supports the notion that this pathway is activated by MTX in vivo and may contribute to the efficacy of MTX in inflammatory disease.

A mathematical model for DNA damage and repair.

In cells, DNA repair has to keep up with DNA damage to maintain the integrity of the genome and prevent mutagenesis and carcinogenesis. While the importance of both DNA damage and repair is clear, the impact of imbalances between both processes has not been studied. In this paper, we created a combined mathematical model for the formation of DNA adducts from oxidative estrogen metabolism followed by base excision repair (BER) of these adducts. The model encompasses a set of differential equations representing the sequence of enzymatic reactions in both damage and repair pathways. By combining both pathways, we can simulate the overall process by starting from a given time-dependent concentration of 17beta-estradiol (E(2)) and 2'-deoxyguanosine, determine the extent of adduct formation and the correction by BER required to preserve the integrity of DNA. The model allows us to examine the effect of phenotypic and genotypic factors such as different concentrations of estrogen and variant enzyme haplotypes on the formation and repair of DNA adducts.