24 research outputs found
Expression of Wnt Receptors in Adult Spiral Ganglion Neurons: Frizzled 9 Localization at Growth Cones of Regenerating Neurites
No full textLittle is known about signaling pathways, besides those of neurotrophic factors, that are operational in adult spiral ganglion neurons. In patients with sensorineural hearing loss, such pathways could eventually be targeted to stimulate and guide neurite outgrowth from the remnants of the spiral ganglion towards a cochlear implant, thereby improving the fidelity of sound transmission. To systematically identify neuronal receptors for guidance cues in the adult cochlea, we conducted a genome-wide cDNA microarray screen with two-month-old CBA/CaJ mice. A meta-analysis of our data and those from older mice in two other studies revealed the presence of neuronal transmembrane receptors that represent all four established guidance pathways—ephrin, netrin, semaphorin, and slit—in the mature cochlea as late as 15 months. In addition, we observed the expression of all known receptors for the Wnt morphogens, whose
neuronal guidance function has only recently been recognized. In situ hybridizations located the mRNAs of the Wnt receptors frizzled 1, 4, 6, 9, and 10 specifically in adult spiral ganglion neurons. Finally, frizzled 9 protein was found in the growth cones of adult spiral ganglion neurons that were regenerating neurites in culture. We conclude from our results that adult spiral
ganglion neurons are poised to respond to neurite damage, owing to the constitutive expression of a large and diverse collection of guidance receptors. Wnt signaling, in particular, emerges as a candidate pathway for guiding neurite outgrowth towards a cochlear implant after sensorineural
hearing loss.is peer reviewedSubmitted by Samit Shah ([email protected]) on 2010-01-20T20:07:37Z
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Previous issue date: 2009-08-28T32 DC006612/DC/NIDCD NIH HHS/United Statespublished or submitted for publicatio
Wnt Signaling in Growth Cone Mediated Neurite Outgrowth from Spiral Ganglion Neurons in the Adult Mouse
No full textProfound sensorineural hearing loss affects nearly 700,000 people in the United States and cannot be treated with hearing aids. Many listeners receive cochlear implants that can restore hearing by directly stimulating spiral ganglion neurons with electrodes implanted in the inner ear. However, the success of cochlear implants in older patients is limited by the reduced availability of surviving neurons that can be targeted with electrical stimulation, the distance between the implanted electrode array and the neuron cell bodies, and the formation of scar tissue at the interface between the remaining nerve fibers and the implanted electrodes. An approach to improving the performance of cochlear implants is to stimulate and guide neurite outgrowth from spiral ganglion neurons toward electrodes to form private channels of communication between the cochlear implant and the targeted neuronal populations. To date, there has been little investigation into the roles of Wnt proteins signaling through their Frizzled receptors in neuro-regeneration in the adult inner ear despite their involvement in axon guidance, dendrite morphogenesis, and synapse formation throughout the developing nervous system. In Chapter II, I show the differential expression of several Frizzled receptors in the spiral ganglion neurons of the adult mouse cochlea in an apical-to-basal gradient, as well as the expression of Frizzled 9 protein in growth cones of regenerating neurites in vitro. Then, in Chapter III, I demonstrate that the activation of canonical Wnt signaling by lithium modulates growth cone mediated neurite outgrowth from adult spiral ganglion neurons by altering the neuronal cytoskeleton. This dissertation research demonstrates that Frizzled-Wnt signaling represents a potential regenerative pathway for the restoration of neuronal connections in the adult inner ear after injury.Item withdrawn by Alexis Thompson ([email protected]) on 2010-12-02T20:41:45Z
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On the characteristic polynomial of the Gross regulator matrix
No full textDasgupta S, Spieß M. ON THE CHARACTERISTIC POLYNOMIAL OF THE GROSS REGULATOR MATRIX. TRANSACTIONS OF THE AMERICAN MATHEMATICAL SOCIETY. 2019;372(2):803-827.We present a conjectural formula for the principal minors and the characteristic polynomial of Gross's regulator matrix associated to a totally odd character of a totally real field. The formula is given in terms of the Eisenstein cocycle, which was defined and studied earlier by the authors and collaborators. For the determinant of the regulator matrix, our conjecture follows from recent work of Kakde, Ventullo, and the first author. For the diagonal entries, our conjecture overlaps with the conjectural formula presented in our prior work. The intermediate cases are new and provide a refinement of the Gross-Stark conjecture
Coronary Physiology in the Cardiac Catheterization Laboratory
No full textCoronary angiography has been the principle modality for assessing the severity of atherosclerotic coronary artery disease for several decades. However, there is a complex relationship between angiographic coronary stenosis and the presence or absence of myocardial ischemia. Recent technological advances now allow for the assessment of coronary physiology in the catheterization laboratory at the time of diagnostic coronary angiography. Early studies focused on coronary flow reserve (CFR) but more recent work has demonstrated the physiologic accuracy and prognostic value of the fractional flow reserve (FFR) and instantaneous wave free ratio (iFR) for the assessment of coronary artery disease. These measurements have been validated in large multi-center clinical trials and have become indispensable tools for guiding revascularization in the cardiac catheterization laboratory. The physiological assessment of chest pain in the absence of epicardial coronary artery disease involves coronary thermodilution to obtain the index of microcirculatory resistance (IMR) or Doppler velocity measurement to determine the coronary flow velocity reserve (CFVR). Physiology-based coronary artery assessment brings “personalized medicine” to the catheterization laboratory and allows cardiologists and referring providers to make decisions based on objective findings and evidence-based treatment algorithms. The purpose of this review is to describe the theory, technical aspects, and relevant clinical trials related to coronary physiology assessment for an intended audience of general medical practitioners
Student perceptions of the use of pre-recorded lecture modules and class exercises in a molecular biology course
No full textTo describe the design, implementation, and assessment of a hybrid learning molecular biology course.
Students were assigned to watch pre-recorded lectures (modules) prior to class. Class time was used for applying the theory in the modules to exercises designed to explore the material at a deeper level. Student perceptions of the use of modules and class exercises as a tool to enhance learning were examined using a survey with a 5-point Likert Disagree–Agree response scale.
One hundred percent of the students participating in the survey indicated that the pre-recorded modules and class exercises helped enhance their learning, and that the hybrid course design effectively combined active and passive learning methods. Over 95% of the students indicated that the course design helped them to learn the material more effectively at all levels of Bloom’s taxonomy compared to a traditional lecture-based course.
Providing students with modules allows them to review a recorded lecture multiple times and learn the course material at their own pace. Use of the modules also frees up classroom time that can then be used for active learning exercises and detailed application of the material. Students believed that combining pre-recorded modules with class exercises allowed them to become more actively engaged in the learning process and develop better understanding of the course material. Students also perceived that the hybrid learning approach in molecular biology promoted better recall, understanding, application, analysis, and integration of the material compared to a traditional lecture-based course
Drug‐coated balloon versus plain old balloon angioplasty in femoropopliteal disease: An updated meta‐analysis of randomized controlled trials
No full text
Low prevalence of hepatitis B and C infections among the healthcare workers despite low vaccination coverage for hepatitis B in Mumbai
No full text<p class="ABS"><span class="ABS_Bold-Italic" lang="en-GB">Background</span><span class="Bold">:</span> The risk of acquiring hepatitis B virus (HBV) and hepatitis C virus (HCV) infections through exposure to blood or its products and contact with other body fluids is high amongst health care workers (HCWs). Despite potential risks, a proportion of HCWs never get vaccinated. This study aimed to investigate the vaccination practices and the prevalence of HBV infection in HCWs. <span class="ABS_Bold-Italic" lang="en-GB">Aims:</span> To determine the prevalence of HBV and HCV, their possible association with occupational and non-occupational risk factors. We also studied the prevalence of vaccination for hepatitis B in different subgroups of study population. <span class="ABS_Bold-Italic" lang="en-GB">Materials and Methods:</span> In this cross-sectional study, total 1347 hospital staffs were screened for hepatitis B and hepatitis C. HBV is detected by HBsAg testing, and HCV is detected by anti-HCV testing by ELISA method. Positive results were confirmed by HBV DNA testing (Qualitative) and HCV RNA testing (Qualitative). A questionnaire used to collect data from study participants was pre-designed by the authors. <span class="ABS_Bold-Italic" lang="en-GB">Results:</span> Out of total 1347 hospital staffs screened, 6 (0.4%) were HBsAg-positive and 2 (0.1%) were anti-HCV-positive. Only 54% had a history of complete vaccination, and 0.3% had incomplete vaccination. Vaccination coverage was highest in residents (76.7%), medical students (68.9%), nursing (66.1%), and teachers (61.4%) and lowest in servants (5.4%), office staff (6.6%), and lab technicians (24.3%). Awareness about the risk factor for transmission of HBV and HCV and complication related to them was 77.7%. It was highest in teachers (93.9%) and residents (97.8%), lowest in servants (16.3%). No statistically significant difference in the exposure to various risk factors among those who are HBsAg or anti-HCV-positive and HBsAg or anti-HCV-negative. <span class="ABS_Bold-Italic" lang="en-GB">Conclusions:</span> The prevalence of HBV and HCV infection is not high in hospital staff than general population. Hepatitis B vaccination coverage was below expectation in all the subgroups even in resident doctors and teachers.</p><div> </div></jats:p
