Resveratrol increases tear production and ocular pain after corneal abrasion in male, but not female, rats using a photorefractive keratectomy model

Photorefractive keratectomy (PRK) is an alternative to LASIK and can cause intense acute pain that is often not relieved by standard treatments. To assess potential therapeutics for this type of acute pain, appropriate preclinical models are needed. We describe a preclinical corneal abrasion rat model that simulates the initial stages of PRK surgery and demonstrates similar pain and tear dysfunction as seen clinically. We used both behavioral and homeostatic assays to determine the therapeutic potential of resveratrol on pain and tear production. Studies were conducted in male and female Sprague-Dawley rats. Heptanol was applied to one eye and the superficial corneal epithelium was removed, mimicking the abrasion used in PRK. Spontaneous pain was assessed with orbital tightening (OT) scores for 7 days. Topical resveratrol increased OT scores sex-specifically in abraded males, but not females, at 72 h and 1 week after abrasion. Resveratrol increased tear production in abraded males, with no effect in abraded females. There was no correlation between OT score at 1 week and tear production measurements, demonstrating no relationship between spontaneous ocular pain and tear dysfunction in this model. These findings demonstrate the usefulness of our corneal abrasion preclinical PRK model for the assessment of ocular pain therapeutics and indicate that topical resveratrol may not be useful for managing PRK-induced pain.

The RNA-Binding Protein HuR Posttranscriptionally Regulates the Protumorigenic Activator YAP1 in Pancreatic Ductal Adenocarcinoma

Yes-associated protein 1 (YAP1) is indispensable for the development of mutant KRAS-driven pancreatic ductal adenocarcinoma (PDAC). High YAP1 mRNA is a prognostic marker for worse overall survival in patient samples; however, the regulatory mechanisms that mediate its overexpression are not well understood. YAP1 genetic alterations are rare in PDAC, suggesting that its dysregulation is likely not due to genetic events. HuR is an RNA-binding protein whose inhibition impacts many cancer-associated pathways, including the "conserved YAP1 signature" as demonstrated by gene set enrichment analysis. Screening publicly available and internal ribonucleoprotein immunoprecipitation (RNP-IP) RNA sequencing (RNA-Seq) data sets, we discovered that YAP1 is a high-confidence target, which was validated in vitro with independent RNP-IPs and 3' untranslated region (UTR) binding assays. In accordance with our RNA sequencing analysis, transient inhibition (e.g., small interfering RNA [siRNA] and small-molecular inhibition) and CRISPR knockout of HuR significantly reduced expression of YAP1 and its transcriptional targets. We used these data to develop a HuR activity signature (HAS), in which high expression predicts significantly worse overall and disease-free survival in patient samples. Importantly, the signature strongly correlates with YAP1 mRNA expression. These findings highlight a novel mechanism of YAP1 regulation, which may explain how tumor cells maintain YAP1 mRNA expression at dynamic times during pancreatic tumorigenesis.

Abstract 3494: Characterizing the relationship between genotype and phenotype in DNA damage response-altered pancreatic cancer models

Alterations in DNA damage response (DDR) proteins are prevalent across cancers and present unique opportunities for the therapeutic induction of synthetic lethality (i.e., two gene deficiencies in the same pathway synergize to kill tumor cells). In pancreatic adenocarcinoma, patients harboring alterations in DDR genes, such as in homology-directed repair (HDR), comprise the 10-20% of patients that may benefit from the recent FDA approval of Olaparib, a poly (ADP-ribose) polymerase inhibitor that disrupts non-homologous end joining (NHEJ). Despite being the best-in-class targeted therapy for DDR-altered pancreatic cancers, a subset of patients fails to respond to Olaparib and those that initially respond eventually go on to develop resistance. The mechanisms underlying resistance are poorly elucidated but suggest that some patients harboring DDR-altered tumors are HDR-proficient or revert to HDR-proficiency during therapy, bypassing the second gene deficiency requisite for synthetic lethal induction with targeted therapy (e.g., Olaparib). Utilizing patient-derived models of cancer, we are actively investigating DDR-altered, pancreatic tumor cell lines and exploring the relationship between DDR-alterations and HDR-deficiency with three goals: [1] To evaluate the prevalence of HDR-proficiency in BRCA-altered tumors, [2] to understand the extent to which patient-derived models of cancer are concordant and predictive of clinical outcomes, and [3] to identify novel therapeutic strategies for resistant patients. So far, we have observed HDR-proficiency by functional assays (e.g., RAD51 foci formation) in DDR-altered patient-derived cell lines that corresponds with poor response to Olaparib in vitro, and resistance to platinum therapy clinically. Whereas DDR-altered HDR-deficient lines had greater sensitivity to Olaparib and platinum therapy. These early data suggest that measures of HDR by functional assay may be more predictive of clinical therapeutic responses than the use of genetic signatures alone.

Citation Format: James R. Carroll, Jason M. Link, Jonathan R. Brody. Characterizing the relationship between genotype and phenotype in DNA damage response-altered pancreatic cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3494.

Analysis of rod/cone gap junctions from the reconstruction of mouse photoreceptor terminals

Electrical coupling, mediated by gap junctions, contributes to signal averaging, synchronization, and noise reduction in neuronal circuits. In addition, gap junctions may also provide alternative neuronal pathways. However, because they are small and especially difficult to image, gap junctions are often ignored in large-scale 3D reconstructions. Here, we reconstruct gap junctions between photoreceptors in the mouse retina using serial blockface-scanning electron microscopy, focused ion beam-scanning electron microscopy, and confocal microscopy for the gap junction protein Cx36. An exuberant spray of fine telodendria extends from each cone pedicle (including blue cones) to contact 40-50 nearby rod spherules at sites of Cx36 labeling, with approximately 50 Cx36 clusters per cone pedicle and 2-3 per rod spherule. We were unable to detect rod/rod or cone/cone coupling. Thus, rod/cone coupling accounts for nearly all gap junctions between photoreceptors. We estimate a mean of 86 Cx36 channels per rod/cone pair, which may provide a maximum conductance of ~1200 pS, if all gap junction channels were open. This is comparable to the maximum conductance previously measured between rod/cone pairs in the presence of a dopamine antagonist to activate Cx36, suggesting that the open probability of gap junction channels can approach 100% under certain conditions.

Intraoperative transesophageal echocardiographic assessment of the effect of protamine on paraprosthetic aortic insufficiency immediately after stentless tissue aortic valve replacement

Mild paravalvular aortic insufficiency (AI) is common immediately after stentless bioprosthetic aortic valve replacement. Although resolution of paraprosthetic jets with protamine has been described, the predictability of resolution has not been addressed. Intraoperative transesophageal echocardiography was performed before and after protamine administration among 2 groups. The first group (n = 20) was used to define the prevalence and severity of paravalvular AI after stentless tissue AVR, and define a threshold value for jet size associated with resolution with protamine. A second group (n = 18) was used to prospectively test the determined threshold. Paravalvular AI occurred in 13 of 20 (65%) patients. Using a threshold value of 0.3 cm or less jet width, prospective testing revealed positive and negative predictive values for AI resolution with protamine of 93% (14 of 15) and 100% (3 of 3), respectively. Protamine administration is associated with resolution of small AI jets immediately after implantation of a stentless aortic bioprosthesis, with a jet width 0.3 cm or less strongly predictive of resolution.

Comparison of vestibulo-ocular reflex (VOR) modification methods in cats

The vestibulo-ocular reflex (VOR) has been measured and optically modified in several animal species. The VOR gain can be increased optokinetically by rotating the animal's visual surround opposite to the animal's direction of rotation or a VOR increase can result from the use of magnifying lenses. We describe here a comparison of three methods for producing VOR increases in cats: (i) optokinetic drum; (ii) a pair of 2.2 x telescopic lenses; (iii) Fresnel lens goggles. The animals were put through several preliminary calibrations followed by a sequence of VOR modification periods alternating with 10 testing periods. The results of the comparison in 4 cats show that the Fresnel lens system produces a greater and more stable VOR gain increase than the other two methods.

Hemoglobin interference with Du Pont Automatic Clinical Analyzer procedure for calcium

Hemoglobin in concentrations of approximately 2.5 g/liter or greater significantly increases values for apparent calcium in serum as determined with the Du Pont aca, an interference attributable to the 575-nm absorption band of oxyhemoglobin being uncompensated by the 577--600 nm differential absorption reading of the calcium o-cresolphthalein complexone complex.

Angioimmunoblastic lymphadenopathy with dysproteinemia

Three cases of angioimmunoblastic lymphadenopathy with dysproteinemia are reported which illustrate the characteristic clinico-pathological features. These cases also provide information relating to the ultrastructure of the interstitial acidophil material, the histopathological spectrum, where treatment has been attempted, and an incidence figure for an Australian community. Detailed immunological investigations in one case suggest that the disease is a primary B-lymphocyte abnormality.

Hemoglobin interference with Du Pont Automatic Clinical Analyzer procedure for calcium

Hemoglobin in concentrations of approximately 2.5 g/liter or greater significantly increases values for apparent calcium in serum as determined with the Du Pont aca, an interference attributable to the 575-nm absorption band of oxyhemoglobin being uncompensated by the 577--600 nm differential absorption reading of the calcium o-cresolphthalein complexone complex.