Autoregulation of Connexin43 Gap Junction Formation by Internally Translated Isoforms

SummaryDuring each heartbeat, intercellular electrical coupling via connexin43 (Cx43) gap junctions enables synchronous cardiac contraction. In failing hearts, impaired Cx43 trafficking reduces gap junction coupling, resulting in arrhythmias. Here we report that internal translation within Cx43 (GJA1) mRNA occurs, resulting in truncated isoforms that autoregulate Cx43 trafficking. We find that at least four truncated Cx43 isoforms occur in the human heart, with a 20 kDa isoform predominating. In-frame AUG codons within GJA1 mRNA are the translation initiation sites and their ablation arrests trafficking of full-length Cx43. The 20 kDa isoform is sufficient to rescue this trafficking defect in trans, suggesting it as a trafficking chaperone for Cx43. Limiting cap-dependent translation through inhibition of mTOR enhances truncated isoform expression, increasing Cx43 gap junction size. The results suggest that internal translation is a mechanism of membrane protein autoregulation and a potent target for therapies aimed at restoring normal electrical coupling in diseased hearts

Filling the gap. Clinical skill acquisition with interactive online modules to supplement traditional instruction

PURPOSE The purpose of this study was to assess the effectiveness of interactive e-learning modules to supplement traditional instruction for range of motion (ROM) clinical skill acquisition in a doctor of physical therapy(DPT) curriculum. BACKGROUNDS/SIGNIFICANCE Online resources have become highly favored to augment learning especially by millennials for convenience, self-paced content, and versatility in learning styles. It has been reported that elearning platforms are as effective as traditional face-to-face instruction, but may be best utilized as an adjunctive resource for teaching psychomotor skills. Student confidence has also been analyzed with reports of increased self-efficacy with use of online learning materials. There are deficiencies in the literature related to the use of e-learning and student outcomes. There are no studies investigating the use of online technologies to supplement ROM skill acquisition and an overall deficiency regarding interactive learning platforms in DPT curriculum. During the last two years at one institution, only about half of the class passed the ROM lab practical on the first attempt. Requests by students for a supplemental resource beyond the textbook as well as faculty searching for an option that would appeal to the millennial generation and address common errors lead to the development of interactive e-learning modules to fill in the gap. This study aims serve as a comprehensive evaluation of modules by analyzing pass rates, confidence, usage, and student satisfaction. We hypothesized the modules would be highly regarded, utilized by students, and result in increased lab practical pass rates. SUBJECTS 52/53 first-year DPT students consented to participate. METHODS AND MATERIALS This was prospective cohort study about supplemental modules created by a faculty-student team to be highly-engaging and media rich where the learner decides the pace and order of content delivered. Embedded quizzes provided immediate feedback for the learner to reflect on their understanding. Modules supplemented 4 labs with faculty demonstrations, peer practice and lab assistant feedback. Students were assessed by a high-stakes lab practical of ROM measurements on a standardized patient: upper extremity (UE), lower extremity(LE) and spine. At the beginning of the semester, students were randomly divided into 2 groups with 1 group receiving access to the UE modules and the other having access to the LE modules. To reduce the crossover effect between the groups and maintain the integrity of the study, students were educated on the importance of only viewing the modules they had access to and faculty were blinded to group assignment. Mid-way through the semester all students had the option to choose if they wanted access to the last set of modules focused on the spine. Students rated confidence on a 10-point Likert scale and self-reported module usage was confirmed by the learning management system. Student satisfaction was assessed by an end of semester course evaluation. ANALYSES Chi-square tests were used to determine associations between groups for lab practical pass rates. Logistic regression was used to analyze differences between cohorts by year (α= 0.05). RESULTS Data was analyzed from 44/52 students. 8 students were excluded (6 for not using modules, 1 had previously taken the class, 1 viewed modules not of their assigned group). There were 34 females and 10 males with a mean age of 23 years (21-28), who reported race as Caucasian (n=41), Asian (n=2) and Hispanic (n=1). There were no significant differences between groups for gender, age or race. The average module usage per person was 2.4hours (10 min-7 hours). The average self-reported confidence for both groups combined increased from 4.3/10 to9.0/10 at the end of the semester. There was no significant difference between groups in the first time lab practical pass rate (p=0.30) and no significant differences in passing the UE (p=0.23) or LE (p=0.66) measurement. The first time lab practical pass rate for all students in 2015 was 71%. Without modules available, first time pass rates were 63% in 2013 and 47% in 2014.Individual year effects show a significant difference between 2015 and 2014 (p=0.02), but no difference for 2015 and2013 (p=0.40).All students requested access to the spine modules. Student satisfaction results of the modules: 78% reported appropriate interactivity, 80% wanted access beyond the semester, 76% said it helped them learn, and 85%recommended using them in the future. CONCLUSIONS The results support the use of interactive e-learning modules to supplement ROM clinical skill acquisition in a DPT curriculum. It appears that the interactive modules were well utilized by the students, increased confidence, and had a high rate of satisfaction as indicated by the course evaluation and students wanting access to the spine modules. Additionally, there were significant improvements in first time pass rates from the previous year when the modules were not available. Our results are congruent with previous studies that reported online technologies are best used to supplement traditional instruction. Limitations include a small sample size from a single institution and the inherent inaccuracies in students’ recall of self-reported data. Strengths include outcomes that went beyond student satisfaction. Furthermore, this interactive module served as a readily accessible resource and allowed students to study at their own pace and learning style. This platform for supplemental materials should be strongly considered for attainment of ROM psychomotor skills and could be valuable for instruction of other foundational clinical skills in physical therapy. FUNDING SOURCE University of Nebraska Medical Center College of Allied Health Professions and the Office of the Vice Chancellor for Academic Affairs

Integrin (alpha 6 beta 4) regulation of eIF-4E activity and VEGF translation: a survival mechanism for carcinoma cells

We define a novel mechanism by which integrins regulate growth factor expression and the survival of carcinoma cells. Specifically, we demonstrate that the alpha 6 beta 4 integrin enhances vascular endothelial growth factor (VEGF) translation in breast carcinoma cells. The mechanism involves the ability of this integrin to stimulate the phosphorylation and inactivation of 4E-binding protein (4E-BP1), a translational repressor that inhibits the function of eukaryotic translation initiation factor 4E (eIF-4E). The regulation of 4E-BP1 phosphorylation by alpha 6 beta 4 derives from the ability of this integrin to activate the PI-3K-Akt pathway and, consequently, the rapamycin-sensitive kinase mTOR that can phosphorylate 4E-BP1. Importantly, we show that this alpha 6 beta 4-dependent regulation of VEGF translation plays an important role in the survival of metastatic breast carcinoma cells by sustaining a VEGF autocrine signaling pathway that involves activation of PI-3K and Akt. These findings reveal that integrin-mediated activation of PI-3K-Akt is amplified by integrin-stimulated VEGF expression and they provide a mechanism that substantiates the reported role of alpha 6 beta 4 in carcinoma progression

Integrin (α6β4) regulation of eIF-4E activity and VEGF translation: a survival mechanism for carcinoma cells

We define a novel mechanism by which integrins regulate growth factor expression and the survival of carcinoma cells. Specifically, we demonstrate that the α6β4 integrin enhances vascular endothelial growth factor (VEGF) translation in breast carcinoma cells. The mechanism involves the ability of this integrin to stimulate the phosphorylation and inactivation of 4E-binding protein (4E-BP1), a translational repressor that inhibits the function of eukaryotic translation initiation factor 4E (eIF-4E). The regulation of 4E-BP1 phosphorylation by α6β4 derives from the ability of this integrin to activate the PI-3K–Akt pathway and, consequently, the rapamycin-sensitive kinase mTOR that can phosphorylate 4E-BP1. Importantly, we show that this α6β4-dependent regulation of VEGF translation plays an important role in the survival of metastatic breast carcinoma cells by sustaining a VEGF autocrine signaling pathway that involves activation of PI-3K and Akt. These findings reveal that integrin-mediated activation of PI-3K–Akt is amplified by integrin-stimulated VEGF expression and they provide a mechanism that substantiates the reported role of α6β4 in carcinoma progression

The Kinematics of Thick Disks in External Galaxies

We present kinematic measurements of the thick and thin disks in two edge-on galaxies. We have derived stellar rotation curves at and above the galaxies' midplanes using Ca II triplet features measured with the GMOS spectrograph on Gemini North. In one galaxy, FGC 1415, the kinematics above the plane show clear rotation that lags that of the midplane by ~20-50%, similar to the behavior seen in the Milky Way. However, the kinematics of the second galaxy, FGC 227, are quite different. The rotation above the plane is extremely slow, showing <25% of the rotation speed of the stars at the midplane. We decompose the observed rotation curves into a superposition of thick and thin disk kinematics, using 2-dimensional fits to the galaxy images to determine the fraction of thick disk stars at each position. We find that the thick disk of FGC 1415 rotates at 30-40% of the rotation speed of the thin disk. In contrast, the thick disk of FGC 227 is very likely counter-rotating, if it is rotating at all. These observations are consistent with the velocity dispersion profiles we measure for each galaxy. The detection of counter-rotating thick disks conclusively rules out models where the thick disk forms either during monolithic collapse or from vertical heating of a previous thin disk. Instead, the data strongly support models where the thick disk forms from direct accretion of stars from infalling satellites.Comment: 13 pages, 10 figures. Accepted for publication in Ap

Fruit and vegetable knowledge and intake within an Australian population: The ausdiab study

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Understanding the relationship between fruit and vegetable knowledge (FVK) and fruit and vegetable intake (FVI) is an important consideration for improved public health and successful targeting of health promotion messaging. The aim of this study was to investigate the association between FVK and FVI in Australian adults and to identify subgroups most at risk of poor knowledge. Using data from the Australian Diabetes, Obesity, and Lifestyle Study (AusDiab), we investigated associations between FVK and FVI, as well as demographic and lifestyle factors. Baseline FVK was measured using two self-reported questions. FVI was assessed using a validated, self-reported, food frequency questionnaire in 1999/00 (baseline), 2004/05, and 2011/12. Amongst the 8966 participants assessed at baseline, 24.1% had adequate, 73.0% had insufficient, and 2.9% had poor FVK. Using linear regression, those with insufficient or poor FVK reported significantly lower FVI (grams/day) compared to those with adequate FVK: baseline (coefficient (95%CI)): −67.1 (−80.0, −54.3) and −124.0 (−142.9, −105.1), respectively, whilst, at 12 years, the differences were −42.5 (−54.6, −30.5) and −94.6 (−133.8, −55.5) grams/day, respectively (all p \u3c 0.001). Poor FVK was more likely to be reported in males, older individuals (\u3e65 years), socio-economically disadvantaged, smokers, and those with insufficient physical activity/sedentary behavior. We demonstrate that having adequate knowledge of FVI, defined as knowing to consume fruit and vegetables several times a day for a well-balanced diet, is strongly associated with FVI, with several demographic and lifestyle factors predicting FVK. Health promotion messages aimed at increasing FVK should target these subgroups for maximal effect

Structural Parameters of Thin and Thick Disks in Edge-On Disk Galaxies

We analyze the global structure of 34 late-type, edge-on, undisturbed, disk galaxies spanning a wide range of mass. We measure structural parameters for the galaxies using two-dimensional least-squares fitting to our $R$-band photometry. The fits require both a thick and a thin disk to adequately fit the data. The thick disks have larger scale heights and longer scale lengths than the embedded thin disks, by factors of ~2 and ~1.25, respectively. The observed structural parameters agree well with the properties of thick and thin disks derived from star counts in the Milky Way and from resolved stellar populations in nearby galaxies. We find that massive galaxies' luminosities are dominated by the thin disk. However, in low mass galaxies (Vc < 120 km/s), thick disk stars contribute nearly half of the luminosity and dominate the stellar mass. Thus, although low mass dwarf galaxies appear blue, the majority of their stars are probably quite old. Our data are most easily explained by a formation scenario where the thick disk is assembled through direct accretion of stellar material from merging satellites while the thin disk is formed from accreted gas. The baryonic fraction in the thin disk therefore constrains the gas-richness of the merging pre-galactic fragments. If we include the mass in HI as part of the thin disk, the thick disk contains <10% of the baryons in high mass galaxies, and ~25-30% of the baryons in low-mass galaxies. We discuss how our trends can be explained by supernova-driven outflow at early times as well as the possibilities for predicting abundance trends in thick disks, and for removing discrepancies between semi-analytic galaxy formation models and the observed colors of low mass galaxies. (abstract abridged)Comment: 25 pages, 24 figures, accepted for publication in A

Calculation of excited polaron states in the Holstein model

An exact diagonalization technique is used to investigate the low-lying excited polaron states in the Holstein model for the infinite one-dimensional lattice. For moderate values of the adiabatic ratio, a new and comprehensive picture, involving three excited (coherent) polaron bands below the phonon threshold, is obtained. The coherent contribution of the excited states to both the single-electron spectral density and the optical conductivity is evaluated and, due to the invariance of the Hamiltonian under the space inversion, the two are shown to contain complementary information about the single-electron system at zero temperature. The chosen method reveals the connection between the excited bands and the renormalized local phonon excitations of the adiabatic theory, as well as the regime of parameters for which the electron self-energy has notable non-local contributions. Finally, it is shown that the hybridization of two polaron states allows a simple description of the ground and first excited state in the crossover regime.Comment: 12 pages, 9 figures, submitted to PR