Retinal Expression of Wnt-Pathway Mediated Genes in Low-Density Lipoprotein Receptor-Related Protein 5 (Lrp5) Knockout Mice

Mutations in low-density lipoprotein receptor-related protein 5 (Lrp5) impair retinal angiogenesis in patients with familial exudative vitreoretinopathy (FEVR), a rare type of blinding vascular eye disease. The defective retinal vasculature phenotype in human FEVR patients is recapitulated in Lrp5 knockout $(Lrp5^{-/-})$ mouse with delayed and incomplete development of retinal vessels. In this study we examined gene expression changes in the developing $Lrp5^{−/−}$ mouse retina to gain insight into the molecular mechanisms that underlie the pathology of FEVR in humans. Gene expression levels were assessed with an Illumina microarray on total RNA from $Lrp5^{−/−}$ and WT retinas isolated on postnatal day (P) 8. Regulated genes were confirmed using RT-qPCR analysis. Consistent with a role in vascular development, we identified expression changes in genes involved in cell-cell adhesion, blood vessel morphogenesis and membrane transport in $Lrp5^{−/−}$ retina compared to WT retina. In particular, tight junction protein claudin5 and amino acid transporter slc38a5 are both highly down-regulated in $Lrp5^{−/−}$ retina. Similarly, several Wnt ligands including Wnt7b show decreased expression levels. Plasmalemma vesicle associated protein (plvap), an endothelial permeability marker, in contrast, is up-regulated consistent with increased permeability in $Lrp5^{−/−}$ retinas. Together these data suggest that Lrp5 regulates multiple groups of genes that influence retinal angiogenesis and may contribute to the pathogenesis of FEVR

Case report: Large left ventricular aneurysm with contained rupture and haemopericardium

Background: Recent advancements in cardiology have significantly decreased the incidence of post-myocardial infarction mechanical complications. When these sequelae occur, they can have high morbidity and mortality and may require aggressive intervention. Case summary: We describe a case of contained rupture of a large left ventricular aneurysm (LVA) presenting with syncope in a 60-year-old male with late presentation myocardial infarction (MI) 6 weeks prior on home triple antithrombotic therapy (TAT). Urgent pericardiocentesis along with imaging techniques including ultrasound, computed tomography angiography (CTA), and cardiac magnetic resonance imaging (MRI) were used for initial diagnosis. Definitive treatment was achieved with excision and repair of the LVA with return to prior functional status 1 month after intervention. Discussion: Highlights of this report emphasize the importance of differential diagnosis consideration of LVA with contained rupture in patient populations with prior late presentation MI and TAT. High clinical suspicion and thorough diagnostic workup with appropriate imaging are important to guide appropriate treatment interventions

Compensatory Cross-Modal Plasticity Persists After Sight Restoration

Sensory deprivation prompts extensive structural and functional reorganizations of the cortex resulting in the occupation of space for the lost sense by the intact sensory systems. This process, known as cross-modal plasticity, has been widely studied in individuals with vision or hearing loss. However, little is known on the neuroplastic changes in restoring the deprived sense. Some reports consider the cross-modal functionality maladaptive to the return of the original sense, and others view this as a critical process in maintaining the neurons of the deprived sense active and operational. These controversial views have been challenged in both auditory and vision restoration reports for decades. Recently with the approval of Luxturna as the first retinal gene therapy (GT) drug to reverse blindness, there is a renewed interest for the crucial role of cross-modal plasticity on sight restoration. Employing a battery of task and resting state functional magnetic resonance imaging (rsfMRI), in comparison to a group of sighted controls, we tracked the functional changes in response to auditory and visual stimuli and at rest, in a group of patients with biallelic mutations in the RPE65 gene ("RPE65 patients") before and 3 years after GT. While the sighted controls did not present any evidence for auditory cross-modal plasticity, robust responses to the auditory stimuli were found in occipital cortex of the RPE65 patients overlapping visual responses and significantly elevated 3 years after GT. The rsfMRI results showed significant connectivity between the auditory and visual areas for both groups albeit attenuated in patients at baseline but enhanced 3 years after GT. Taken together, these findings demonstrate that (1) RPE65 patients present with an auditory cross-modal component; (2) visual and non-visual responses of the visual cortex are considerably enhanced after vision restoration; and (3) auditory cross-modal functions did not adversely affect the success of vision restitution. We hypothesize that following GT, to meet the demand for the newly established retinal signals, remaining or dormant visual neurons are revived or unmasked for greater participation. These neurons or a subset of these neurons respond to both the visual and non-visual demands and further strengthen connectivity between the auditory and visual cortices

Compensatory Cross-Modal Plasticity Persists After Sight Restoration

Sensory deprivation prompts extensive structural and functional reorganizations of the cortex resulting in the occupation of space for the lost sense by the intact sensory systems. This process, known as cross-modal plasticity, has been widely studied in individuals with vision or hearing loss. However, little is known on the neuroplastic changes in restoring the deprived sense. Some reports consider the cross-modal functionality maladaptive to the return of the original sense, and others view this as a critical process in maintaining the neurons of the deprived sense active and operational. These controversial views have been challenged in both auditory and vision restoration reports for decades. Recently with the approval of Luxturna as the first retinal gene therapy (GT) drug to reverse blindness, there is a renewed interest for the crucial role of cross-modal plasticity on sight restoration. Employing a battery of task and resting state functional magnetic resonance imaging (rsfMRI), in comparison to a group of sighted controls, we tracked the functional changes in response to auditory and visual stimuli and at rest, in a group of patients with biallelic mutations in the RPE65 gene ("RPE65 patients") before and 3 years after GT. While the sighted controls did not present any evidence for auditory cross-modal plasticity, robust responses to the auditory stimuli were found in occipital cortex of the RPE65 patients overlapping visual responses and significantly elevated 3 years after GT. The rsfMRI results showed significant connectivity between the auditory and visual areas for both groups albeit attenuated in patients at baseline but enhanced 3 years after GT. Taken together, these findings demonstrate that (1) RPE65 patients present with an auditory cross-modal component; (2) visual and non-visual responses of the visual cortex are considerably enhanced after vision restoration; and (3) auditory cross-modal functions did not adversely affect the success of vision restitution. We hypothesize that following GT, to meet the demand for the newly established retinal signals, remaining or dormant visual neurons are revived or unmasked for greater participation. These neurons or a subset of these neurons respond to both the visual and non-visual demands and further strengthen connectivity between the auditory and visual cortices

Internal Medicine Residency Program Director Support and Burnout During the COVID-19 Pandemic: Results of a National Survey

Background: Burnout is common among physicians and physician leaders, including residency program directors (PDs). The effects of the COVID-19 pandemic and other stressors in 2020 on PDs is unknown. Objective: To measure the prevalence of burnout among internal medicine (IM) residency PDs 6 months into the COVID-19 pandemic. Methods: A total of 429 IM PDs, representing 83% of accredited residency programs, were surveyed from August to December 2020. Burnout, using a 2-item screening tool, and self-reported consideration of resigning in 2020, were compared to their annual prevalence since 2012 and tested for possible associations with pandemic stressors and program characteristics. Results: The survey response rate was 61.5% (264 of 429). One-third (33.6%, 87 of 259) of PD respondents met burnout criteria, and 45.1% (110 of 244) reported considering resigning in the past year, which were within the range of preceding years. PDs who reported feeling highly supported by institutional leadership were less likely to meet burnout criteria and to have considered resigning. There were no associations between burnout or consideration of resigning and the amount of clinical time PDs spent in their roles, duration of maximum stress on programs, budget cuts to programs, or geographic region. Conclusions: The prevalence of burnout among PDs in fall 2020 was similar to the prevalence of burnout in pre-pandemic years despite uniquely extreme stressors. PDs\u27 perception of being highly supported by institutional leadership was associated with lower prevalence of burnout and consideration of resigning. Perceived leadership support may be a protective factor against burnout during periods of high stress

Incidence and prevalence of hypertension in 18–40‐year‐old patients referred for palpitations with normal cardiac monitor findings

Abstract Sixteen percent of patients referred for cardiology evaluation are found to have no cause for palpitations. Studies show that hypertension intricately influences “heart rate” and “contractility,?” the key components of “palpitation.” While the prevalence of hypertension is 22.4% in 18–39‐year‐olds, the relationship between palpitations and hypertension remains unknown in this age group. In our study, we assessed the incidence and prevalence of hypertension over 5 years in 18–40‐year‐olds referred for palpitations who had no known arrhythmic cause for palpitations between January 1, 206 and December 31, 2017. We found that over a period of 2.2 (0.7–4.1) years, an additional 56% patients were diagnosed with stage 1 (65/130) and stage 2 (28/130) hypertension, increasing the prevalence from 16% at the start of the study period to 72% at the end of the study period (p < .0001). Hypertensive patients were obese (BMI: 29 [24–36] kg/m2 vs. 25 [22–31] kg/m2; p = .03), used nonsteroidal anti‐inflammatory drugs (NSAIDs) (62 vs. 35%; p = .04), had a stronger family history of hypertension (55 vs. 4%; p < .0001) and exhibited higher systolic (124[120–130] mmHg vs. 112[108–115] mmHg; p < .0001) and diastolic (80[76–83] mmHg vs. 72[69–75] mmHg; p < .0001) blood pressures. Hypertension is commonly diagnosed in 18–40‐year‐old predominantly white female patients referred for palpitations without a known arrhythmic cause. The possibility of untreated hypertension causing palpitations in this cohort needs further evaluation

Wnt Signaling Mediates Pathological Vascular Growth in Proliferative Retinopathy Clinical Perspective

BACKGROUND: Ischemic proliferative retinopathy, characterized by pathological retinal neovascularization, is a major cause of blindness in working-age adults and children. Defining the molecular pathways distinguishing pathological neovascularization from normal vessels is critical to controlling these blinding diseases with targeted therapy. Because mutations in Wnt signaling cause defective retinal vasculature in humans with some characteristics of the pathological vessels in retinopathy, we investigated the potential role of Wnt signaling in pathological retinal vascular growth in proliferative retinopathy. METHODS AND RESULTS: In this study, we show that Wnt receptors (Frizzled4 and low-density lipoprotein receptor-related protein5 [Lrp5]) and activity are significantly increased in pathological neovascularization in a mouse model of oxygen-induced proliferative retinopathy. Loss of Wnt coreceptor Lrp5 and downstream signaling molecule dishevelled2 significantly decreases the formation of pathological retinal neovascularization in retinopathy. Loss of Lrp5 also affects retinal angiogenesis during development and formation of the blood-retinal barrier, which is linked to significant downregulation of tight junction protein claudin5 in Lrp5(-/-) vessels. Blocking claudin5 significantly suppresses Wnt pathway-driven endothelial cell sprouting in vitro and developmental and pathological vascular growth in retinopathy in vivo. CONCLUSIONS: These results demonstrate an important role of Wnt signaling in pathological vascular development in retinopathy and show a novel function of Cln5 in promoting angiogenesis

Selected groups of genes regulated in <i>Lrp5^−/−</i> retina.

<p>Note: Retinas were isolated from P8 <i>Lrp5^−/−</i> mice and age matched WT control mice. RNA was isolated and assessed with Illumina gene expression microarray. (−) indicates decreased expression in <i>Lrp5^−/−</i> retina and (+) indicates increased expression in <i>Lrp5^−/−</i> retina compared to WT control.</p