PRMT1 promotes epigenetic reprogramming associated with acquired chemoresistance in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) carries a dismal prognosis due to therapeutic resistance. We show that PDAC cells undergo global epigenetic reprogramming to acquire chemoresistance, a process that is driven at least in part by protein arginine methyltransferase 1 (PRMT1). Genetic or pharmacological PRMT1 inhibition impairs adaptive epigenetic reprogramming and delays acquired resistance to gemcitabine and other common chemo drugs. Mechanistically, gemcitabine treatment induces translocation of PRMT1 into the nucleus, where its enzymatic activity limits the assembly of chromatin-bound MAFF/BACH1 transcriptional complexes. Cut&Tag chromatin profiling of H3K27Ac, MAFF, and BACH1 suggests a pivotal role for MAFF/BACH1 in global epigenetic response to gemcitabine, which is confirmed by genetically silencing MAFF. PRMT1 and MAFF/BACH1 signature genes identified by Cut&Tag analysis distinguish gemcitabine-resistant from gemcitabine-sensitive patient-derived xenografts of PDAC, supporting the PRMT1-MAFF/BACH1 epigenetic regulatory axis as a potential therapeutic avenue for improving the efficacy and durability of chemotherapies in patients of PDAC.

Spontaneously evolved progenitor niches escape Yap oncogene addiction in advanced pancreatic ductal adenocarcinomas.

Lineage plasticity has been proposed as a major source of intratumoral heterogeneity and therapeutic resistance. Here, by employing an inducible genetic engineered mouse model, we illustrate that lineage plasticity enables advanced Pancreatic Ductal Adenocarcinoma (PDAC) tumors to develop spontaneous relapse following elimination of the central oncogenic driver - Yap. Transcriptomic and immunohistochemistry analysis of a large panel of PDAC tumors reveals that within high-grade tumors, small niches of PDAC cells gradually evolve to re-activate pluripotent transcription factors (PTFs), which lessen their dependency on Yap. Comprehensive Cut&Tag analysis demonstrate that although acquisition of PTF expression is coupled with the process of epithelial-to-mesenchymal transition (EMT), PTFs form a core transcriptional regulatory circuitry (CRC) with Jun to overcome Yap dependency, which is distinct from the classic TGFb-induced EMT-TF network. A chemical-genetic screen and follow-up functional studies establish Brd4 as an epigenetic gatekeeper for the PTF-Jun CRC, and strong synergy between BET and Yap inhibitors in blocking PDAC growth.

Cardiac Reoperations in Patients With Transcatheter Aortic Bioprosthesis.

BACKGROUND: Despite the rapid adoption of transcatheter aortic valve replacement (TAVR), the frequency and clinical outcomes of reoperation after TAVR are not well-described. METHODS: Between 2011 and 2020, 1719 patients underwent a TAVR at our institution. Among these, 32 patients (2%) required a reoperation. Additionally, 16 patients who received a TAVR at another institution received a reoperation at our institution. We retrospectively reviewed these 48 patients. The median interval from TAVR to reoperation was 2.3 years. RESULTS: Primary reoperations included 37 TAVR valve explants (TAVR-explant; 77%) with surgical aortic valve replacement (SAVR), 8 mitral repairs/replacements (17%), 2 coronary artery bypass grafting procedures (4%), and 1 tricuspid valve replacement (2%). Forty-nine percent of nonaortic valve cardiac lesions were present at the time of TAVR. Furthermore, 18 TAVR-explant patients (49%) were deemed anatomically unsuitable for repeat TAVR based on the index TAVR imaging. During TAVR-explant, 6 patients (13%) with native TAVR sustained various degrees of aortic trauma. Patients with unplanned aortic repair demonstrated a smaller sinotubular junction diameter than those without unplanned repair. In contrast, no unplanned aortic repair was needed in the 14 patients with previous SAVR or the latest 20 consecutive patients. The overall in-hospital mortality was 15%, with an observed-to-expected morality ratio of 1.8. CONCLUSIONS: The clinical impact of post-TAVR reoperation remains substantial despite the lower frequency of unplanned aortic repair over time. The necessity of reoperations or unfavorable repeat TAVR anatomy appears predictable at the time of the index TAVR, and implanters must be mindful of "lifetime management" strategy during candidate selection.

Aortic valve reintervention after transcatheter aortic valve replacement.

BACKGROUND: Despite the rapid adoption of transcatheter aortic valve replacement (TAVR), there are scant data regarding aortic valve reintervention after initial TAVR. METHODS: Between 2011 and 2019, 1487 patients underwent a TAVR at the University of Michigan. Among these, 24 (1.6%) patients required an aortic valve reintervention. Additionally, 4 patients who received a TAVR at another institution underwent a valve reintervention at our institution. We retrospectively reviewed these 28 patients. RESULTS: The median age was 72 years, 36% were female and 86% of implanted TAVR devices were self-expandable. The leading indications for reintervention were structural valve degeneration (39%) and paravalvular leak (36%). The cumulative incidence of aortic valve reintervention was 4.6% at 8 years. Most (71%) were deemed unsuitable for repeat TAVR because of the need for concurrent cardiac procedures (50%), unfavorable anatomy (45%), or endocarditis (10%). TAVR valve explant was associated with frequent concurrent procedures, consisting of aortic repair (35%), mitral repair/replacement (35%), tricuspid repair (25%), and coronary artery bypass graft (20%). Seventy-one percent of aortic procedures were unplanned but proved necessary because of severe adhesion of the devices to the contacting tissue. There were 3 (15%) in-hospital mortalities in the TAVR valve explant group, whereas there was no mortality in the repeat TAVR group. CONCLUSIONS: Repeat TAVR procedure was frequently not feasible because of unfavorable anatomy and/or the need for concurrent cardiac procedures. Careful assessment of TAVR procedure repeatability should be weighed at the initial TAVR workup especially in younger patients who are expected to require a valve reintervention.

Sociodemographic variables associated with risk for diabetic retinopathy.

BACKGROUND: Several systemic and sociodemographic factors have been associated with the development and progression of diabetic retinopathy (DR). However, there is limited investigation of the potential role sociodemographic factors may play in augmenting systemic risk factors of DR. We hypothesize that age, sex, race, ethnicity, income, and insurance payor have an impact on hemoglobin A1c (HbA1c), body mass index, and systolic blood pressure, and therefore an upstream effect on the development of DR and vision-threatening forms of DR (VTDR). METHODS: Multivariable analysis of longitudinal electronic health record data at a large academic retina clinic was performed. Sociodemographic factors included race, ethnicity, income, and insurance payor. Systemic risk factors for DR included hemoglobin A1c (HbA1c), systolic blood pressure (SBP), and body mass index (BMI). VTDR was identified from encounter diagnostic codes indicating proliferative retinopathy or diabetic macular edema. Patient-reported primary address zip codes were used to approximate income level, stratified into quartiles. RESULTS: From 2016 to 2018, 3,470 patients with diabetes totaled 11,437 visits were identified. Black patients had higher HbA1c and SBP compared to White patients. White patients had higher BMI and SBP compared to patients of unknown/other race and greater odds of VTDR than the latter. Patients of Hispanic ethnicity had significantly higher SBP than non-Hispanic patients. Low-income patients had higher BMI and SBP than high-income patients and greater odds of VTDR than the latter. Medicaid recipients had greater odds of VTDR than those with Blue Care Network (BCN) and Blue Cross Blue Shield (BCBS) insurance. Medicaid and Medicare recipients had higher SBP compared to BCBS recipients. Finally, both higher HbA1c and SBP had greater odds of VTDR. There were no differences in odds of VTDR between White and Black patients or between Hispanic and non-Hispanic patients. CONCLUSION: Significant associations exist between certain sociodemographic factors and well-known risk factors for DR. Income and payor were associated with increased severity of systemic risk factors and presence of VTDR. These results warrant further investigation of how risk factor optimization and disease prevention may be further improved by targeted intervention of these modifiable sociodemographic factors.

Surgical Explantation of Transcatheter Aortic Bioprostheses: Balloon vs Self-Expandable Devices.

BACKGROUND: Despite the rapid adoption of transcatheter aortic replacement (TAVR), surgical TAVR valve explantation (TAVR-explant) and the clinical impact of explanted TAVR device type are not well described. METHODS: TAVR-explant from 2016 to 2019 was queried using the Society of Thoracic Surgeons (STS) National Database. A total of 483 patients with documented explanted valve type, consisting of 330 (68%) patients with balloon-expandable and 153 (32%) patients with self-expandable devices, were identified. The primary outcome was 30-day mortality. The secondary outcome was the need for any simultaneous procedures with TAVR-explant. RESULTS: The mean age was 72.8 years, 38% of the patients were female, and 51% demonstrated New York Heart Association functional class III to IV symptoms. During TAVR-explant, 63% of patients required other simultaneous procedures, including aortic repair (27%), mitral procedures (22%), coronary artery bypass grafting (15%), and tricuspid procedures (7%). Patients with a self-expandable device underwent more frequent ascending aortic replacement (22% vs 9%; P < .001) than those with a balloon-expandable device, whereas the aortic root replacement rate was similar (19% vs 24%; P = .22). The overall 30-day mortality was 18% without differences in the mortality or other major complications between the groups. Of the 157 patients with isolated surgical aortic valve replacement and available STS predicted risk of mortality score, the observed-to-expected (O/E) mortality ratio was 2.2. CONCLUSIONS: The TAVR-explant outcomes were comparable between patients with balloon-expandable devices and patients with self-expandable devices, whereas ascending aortic replacement was observed more frequently in patients with self-expandable devices. Younger patients undergoing TAVR should be informed of the future TAVR-explant risk that may accompany a higher O/E ratio and frequent morbid concurrent procedures.

Clinical manifestations of intravitreal bortezomib injection.

PURPOSE: To describe the clinical presentation and ocular manifestations of intravitreal bortezomib. OBSERVATIONS: Retrospective chart review of five patients who inadvertently received intravitreal injection of bortezomib, instead of bevacizumab, showed that all patients presented hyperacutely within 24-72 hours of the injection with pain and severe vision loss. Examination revealed a fibrinous anterior uveitis, corneal edema, and choroidal effusion associated with a shallow anterior chamber and secondary angle closure glaucoma. Significant vitritis was notably absent. Severe retinal vascular attenuation and optic atrophy, and sometimes even retinal infarction or detachment, followed. Four of the five patients rapidly progressed to no light perception vision. Vitreous gram stain and cultures were negative in all eyes. CONCLUSIONS AND IMPORTANCE: Intravitreal bortezomib is severely toxic to the eye. Special safeguards should be instituted for the dispensing of intravitreal medications.

Assessing the Pyloric Caeca and Distal Gut Microbiota Correlation with Flesh Color in Atlantic Salmon (Salmo salar L., 1758).

The Atlantic salmon (Salmo salar L., 1758) is a temperate fish species native to the northern Atlantic Ocean. The distinctive pink-red flesh color (i.e., pigmentation) significantly affects the market price. Flesh paleness leads to customer dissatisfaction, a loss of competitiveness, a drop in product value and, consequently, severe economic losses. This work extends our knowledge on salmonid carotenoid dynamics to include the interaction between the gut microbiota and flesh color. A significant association between the flesh color and abundance of specific bacterial communities in the gut microbiota suggests that color may be affected either by seeding resilient beneficial bacteria or by inhibiting the negative effect of pathogenic bacteria. We sampled 96 fish, which covered all phenotypes of flesh color, including the average color and the evenness of color of different areas of the fillet, at both the distal intestine and the pyloric caeca of each individual, followed by 16S rRNA sequencing at the V3-V4 region. The microbiota profiles of these two gut regions were significantly different; however, there was a consistency in the microbiota, which correlated with the flesh color. Moreover, the pyloric caeca microbiota also showed high correlation with the evenness of the flesh color (beta diversity index, PERMANOVA, p = 0.002). The results from the pyloric caeca indicate that Carnobacterium, a group belonging to the lactic acid bacteria, is strongly related to the flesh color and the evenness of the color between the flesh areas.

Outcomes of resident-performed laser-assisted vs traditional phacoemulsification.

PURPOSE: To compare the effectiveness of femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification cataract surgery (CPS) by resident surgeons. SETTING: Parkland Memorial Health and Hospital System, Dallas, Texas, USA. DESIGN: Prospective randomized study. METHODS: All surgeries to be performed by postgraduate year 3 and year 4 residents from October 2015 through June 2017 were eligible for inclusion. Patients were required to complete postoperative day 1, week 1, month 1, and month 3 visits. Specular microscopy was performed preoperatively and postoperatively. Surgeries were filmed, and each step was timed and compared. Surgeon and patient surveys were filled out postoperatively. RESULTS: Of the 135 eyes of 96 subjects enrolled in the study, 64 eyes received FLACS and 71 eyes received CPS. There was no significant difference in corrected distance visual acuity (CDVA), either preoperatively or at the postoperative day 1, week 1, month 1, or month 3 visits (P = .469, .539, .701, .777, and .777, respectively). Cumulated dissipated energy and irrigation fluid usage were not different between FLACS and CPS (P = .521 and .368, respectively), nor was there a difference in the reduction of endothelial cell counts postoperatively (P = .881). Wound creation (P = .014), cortical cleanup (P = .009), and IOL implantation (P = .031) were faster in the CPS group. Survey results indicated that the overall patient experience was similar for FLACS and CPS. CONCLUSIONS: This first prospective randomized trial evaluating resident-performed FLACS shows that, in resident hands, FLACS provides similar results to CPS regarding visual acuity, endothelial cell loss, operative time, patient satisfaction, and surgical complication rate.

Atlantic Salmon (Salmo salar L., 1758) Gut Microbiota Profile Correlates with Flesh Pigmentation: Cause or Effect?

In Tasmania (Australia), during the marine phase, it has been observed that flesh pigmentation significantly drops in summer, possibly due to high water temperatures (> 20 °C). Although this deleterious effect of summer temperatures has been ascertained, there is a lack of knowledge of the actual mechanisms behind the impaired uptake and/or loss of pigments in Atlantic salmon in a challenging environment. Since the microbial community in the fish intestine significantly changes in relation to the variations of water temperature, this study was conducted to assess how the gut microbiota profile also correlates with the flesh color during temperature fluctuation. We sampled 68 fish at three time points covering the end of summer to winter at a marine farm in Tasmania, Australia. Flesh color was examined in two ways: the average color throughout and the evenness of the color between different areas of the fillet. Using 16S rRNA sequencing of the v3-v4 region, we determined that water temperature corresponded to changes in the gut microbiome both with alpha diversity (Kruskal-Wallis tests P = 0.05) and beta diversity indices (PERMANOVA P = 0.001). Also, there was a significant correlation between the microbiota and the color of the fillet (PERMANOVA P = 0.016). There was a high abundance of Pseudoalteromonadaceae, Enterobacteriaceae, Microbacteriaceae, and Vibrionaceae in the pale individuals. Conversely, carotenoid-synthesizing bacteria families (Bacillaceae, Mycoplasmataceae, Pseudomonas, Phyllobacteriaceae, and Comamonadaceae) were found in higher abundance in individuals with darker flesh color.

A Yap-Myc-Sox2-p53 Regulatory Network Dictates Metabolic Homeostasis and Differentiation in Kras-Driven Pancreatic Ductal Adenocarcinomas.

Employing inducible genetically engineered and orthotopic mouse models, we demonstrate a key role for transcriptional regulator Yap in maintenance of Kras-mutant pancreatic tumors. Integrated transcriptional and metabolomics analysis reveals that Yap transcribes Myc and cooperates with Myc to maintain global transcription of metabolic genes. Yap loss triggers acute metabolic stress, which causes tumor regression while inducing epigenetic reprogramming and Sox2 upregulation in a subset of pancreatic neoplastic cells. Sox2 restores Myc expression and metabolic homeostasis in Yap-deficient neoplastic ductal cells, which gradually re-differentiate into acinar-like cells, partially restoring pancreatic parenchyma in vivo. Both the short-term and long-term effects of Yap loss in inducing cell death and re-differentiation, respectively, are blunted in advanced, poorly differentiated p53-mutant pancreatic tumors. Collectively, these findings reveal a highly dynamic and interdependent metabolic, transcriptional, and epigenetic regulatory network governed by Yap, Myc, Sox2, and p53 that dictates pancreatic tumor metabolism, growth, survival, and differentiation.

YAP/TAZ Signaling and Resistance to Cancer Therapy.

Drug resistance is a major challenge in cancer treatment. Emerging evidence indicates that deregulation of YAP/TAZ signaling may be a major mechanism of intrinsic and acquired resistance to various targeted and chemotherapies. Moreover, YAP/TAZ-mediated expression of PD-L1 and multiple cytokines is pivotal for tumor immune evasion. While direct inhibitors of YAP/TAZ are still under development, FDA-approved drugs that indirectly block YAP/TAZ activation or critical downstream targets of YAP/TAZ have shown promise in the clinic in reducing therapy resistance. Finally, BET inhibitors, which reportedly block YAP/TAZ-mediated transcription, present another potential venue to overcome YAP/TAZ-induced drug resistance.

Crustacean larval factor shares structural characteristics with the insect-specific follicle cell protein.

Literature on the cuticle formation in larval stages of the diverse group of decapod crustaceans is lacking, as opposed to a wealth of knowledge in several insect groups. Here we provide the first glimpse of the cuticular organisation in larvae of the eastern spiny lobster Sagmariasus verreauxi. A bioinformatic approach applied to S. verreauxi transcriptome through metamorphosis identified for the first time a small secreted protein with multiple isoforms that is highly expressed in crustacean larvae. This protein, named crustacean larval factor (Clf) shares structural characteristics with insect follicle cell protein 3 (FCP3), an insect-specific, rapidly evolving protein, with spatial-temporal regulated expression that is restricted to follicular cells during the production of the vitellin coat. Furthermore, we identified the FCP3 domain in additional structural proteins in multiple arthropod groups. Recombinant Clf inhibited in vitro calcium carbonate crystalline precipitation, in keeping with the finding that the spiny lobster larval cuticle is mainly composed of amorphous calcium carbonate. In addition, the recombinant Clf was shown to bind chitosan. Taken together, this research identifies two novel structural domains with lineage-specific expansion across arthropods. In crustaceans, Clf is found predominantly in larvae and the spatial-temporal regulated FCP3 factor occurs as a domain identified in multiple structural proteins across arthropods. Given the shared ten cysteines backbone between the Clf and FCP domains, a shared evolution is suggested and should be further explored.

Amylin receptor activation in the ventral tegmental area reduces motivated ingestive behavior.

Amylin is produced in the pancreas and the brain, and acts centrally to reduce feeding and body weight. Recent data show that amylin can act in the ventral tegmental area (VTA) to reduce palatable food intake and promote negative energy balance, but the behavioral mechanisms by which these effects occur are not fully understood. The ability of VTA amylin signaling to reduce intake of specific palatable macronutrients (fat or carbohydrate) was tested in rats in several paradigms, including one-bottle acceptance tests, two-bottle choice tests, and a free-choice diet. Data show that VTA amylin receptor activation with the amylin receptor agonist salmon calcitonin (sCT) preferentially and potently reduces intake of fat, with more variable suppression of sucrose intake. Intake of a non-nutritive sweetener is also decreased by intra-VTA administration of sCT. As several feeding-related signals that act in the mesolimbic system also impact motivated behaviors besides feeding, we tested the hypothesis that the suppressive effects of amylin signaling in the VTA extend to other motivationally relevant stimuli. Results show that intra-VTA sCT reduces water intake in response to central administration of the dipsogenic peptide angiotensin II, but has no effect on ad libitum water intake in the absence of food. Importantly, open field and social interaction studies show that VTA amylin signaling does not produce anxiety-like behaviors. Collectively, these findings reveal a novel ability of VTA amylin receptor activation to alter palatable macronutrient intake, and also demonstrate a broader role of VTA amylin signaling for the control of motivated ingestive behaviors beyond feeding.

TOWARDS A TREATMENT FOR DIABETIC RETINOPATHY: Intravitreal Toxicity and Preclinical Safety Evaluation of Inducible Nitric Oxide Synthase Inhibitors.

BACKGROUND: The purpose of this study is to determine the maximum tolerated dose of a single intravitreal injection of aminoguanidine and 1400W, 2 inhibitors of inducible nitric oxide synthase, in rabbit eyes. Inhibition of inducible nitric oxide synthase has already been shown to be beneficial in various animal models of diabetic eye disease. METHODS: Groups of 4 New Zealand white rabbits were injected with balanced salt solution in the right eye and a single dose of either aminoguanidine (5, 1, 0.25 mg) or 1400W (2 mg and 0.4 mg) in the left eye. Toxicity was assessed by slit-lamp and fundus examination, intraocular pressure and pachymetric measurements, and electrophysiologic and histologic analysis. RESULTS: Eyes injected with high doses of aminoguanidine (5 mg) or 1400W (2 mg) demonstrated severe retinal vascular attenuation and infarction. Lower doses of intravitreal aminoguanidine (1 mg) and 1400W (0.4 mg) caused no significant toxic ocular effects in rabbit eyes. CONCLUSION: If the difference in vitreal volume between rabbit eyes and human eyes is taken into account, aminoguanidine (2.7 mg) and 1400W (1 mg) would be reasonable intravitreal doses to test for safety and efficacy in early clinical trials.

Poor outcomes despite aspirin or statin use in high-risk patients with retinal vein occlusion.

PURPOSE: Since atherosclerosis contributes to the pathophysiology of retinal vein occlusion (RVO), we aimed to assess the effects of aspirin and statins on the visual outcomes of RVO in high-risk patients, whom we define to have hypertension and open-angle glaucoma prior to RVO. METHODS: We conducted a retrospective case-control study of adults diagnosed with RVO between 2006 and 2014. To evaluate for a preventive effect of these medications, we compared the prevalence of aspirin or statin use (either separately or concomitantly) among high-risk patients who developed RVO and among those who did not during at least 2 years of follow-up. To evaluate for a therapeutic effect, we then compared the final follow-up visual acuity (VA) of high-risk RVO patients who had and who had not been taking a statin prior to the RVO. RESULTS: We analyzed 43 eyes [23 central RVOs (CRVOs), 16 branch RVOs (BRVOs), and 4 hemi-RVOs (HRVOs)] from 42 high-risk patients, along with 129 high-risk controls. There was no significant difference (p = 0.47) in aspirin exposure between the control (60%) and RVO (67%) groups, and the increased statin exposure among controls (72% vs. 53% for the cases; p = 0.03) paralleled their higher prevalence of hyperlipidemia. The non-statin and statin RVO groups each had a mean VA of 20/800 at a mean 30 and 43 months of follow-up, respectively. CONCLUSIONS: No preventive benefit of aspirin or statins, and no therapeutic benefit of statins, was found for RVO in high-risk patients. High-risk RVO patients suffer substantially worse outcomes than those reported in other studies not limited to such patients.

Rac1-Mediated DNA Damage and Inflammation Promote Nf2 Tumorigenesis but Also Limit Cell-Cycle Progression.

Merlin encoded by the Nf2 gene is a bona fide tumor suppressor that has been implicated in regulation of both the Hippo-Yap and Rac1-Pak1 pathways. Using genetically engineered murine liver models, we show that co-deletion of Rac1 with Nf2 blocks tumor initiation but paradoxically exacerbates hepatomegaly induced by Nf2 loss, which can be suppressed either by treatment with pro-oxidants or by co-deletion of Yap. Our results suggest that while Yap acts as the central driver of proliferation during Nf2 tumorigenesis, Rac1 primarily functions as an inflammation switch by inducing reactive oxygen species that, on one hand, induce nuclear factor κB signaling and expression of inflammatory cytokines, and on the other activate p53 checkpoint and senescence programs dampening the cyclin D1-pRb-E2F1 pathway. Interestingly, senescence markers are associated with benign NF2 tumors but not with malignant NF2 mutant mesotheliomas, suggesting that senescence may underlie the benign nature of most NF2 tumors.