Publications by authors named "Kenneth Kramer"

Introduction: Hair cells (HCs) are the sensory receptors of the auditory and vestibular systems in the inner ears of vertebrates that selectively transduce mechanical stimuli into electrical activity. Although all HCs have the hallmark stereocilia bundle for mechanotransduction, HCs in non-mammals and mammals differ in their molecular specialization in the apical, basolateral, and synaptic membranes. HCs of non-mammals, such as zebrafish (zHCs), are electrically tuned to specific frequencies and possess an active process in the stereocilia bundle to amplify sound signals.

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Carnitine palmitoyltransferase 2 (CPT2) is an inner mitochondrial membrane protein of the carnitine shuttle and is involved in the beta-oxidation of long chain fatty acids. Beta-oxidation provides an alternative pathway of energy production during early development and starvation. CPT2 deficiency is a genetic disorder that we recently showed can be associated with schizophrenia.

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Article Synopsis
  • Clerkships are critical for medical students to combine their basic science knowledge with hands-on clinical practice, particularly in anatomy, which is vital for effective patient care.
  • Concerns persist about medical students' anatomy knowledge falling short of the expectations of clerkship directors and clinical faculty, indicating a potential gap in training.
  • A study surveying 525 clinical faculty across 24 schools identified that 91% of anatomical structures are deemed essential for core clerkships, highlighting specific anatomy needs for clerkships like family medicine, emergency medicine, and general surgery.
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Building precise neural circuits necessitates the elimination of axonal projections that have inaccurately formed during development. Although axonal pruning is a selective process, how it is initiated and controlled in vivo remains unclear. Here, we show that trans-axonal signaling mediated by the cell surface molecules Glypican-3, Teneurin-3, and Latrophilin-3 prunes misrouted retinal axons in the visual system.

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The current nomenclature for atypical antipsychotics does not indicate that they are used to treat nonpsychotic conditions (eg, bipolar disorder, major depressive disorder), which could have negative implications for both health care providers (HCPs) and patients. The objective of this study was to evaluate how the atypical antipsychotic class name affects HCPs who treat bipolar disorder and patients who receive the diagnosis. Nationwide surveys of primary care and psychiatric HCPs (n = 200) and patients with bipolar disorder (n = 200) were conducted to assess perspectives regarding current atypical antipsychotic nomenclature.

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Non-mammalian vertebrates, including zebrafish, retain the ability to regenerate hair cells (HCs) due to unknown molecular mechanisms that regulate proliferation and conversion of non-sensory supporting cells (nsSCs) to HCs. This regenerative capacity is not conserved in mammals. Identification of uniquely expressed orthologous genes in zebrafish nsSCs may reveal gene candidates involved in the proliferation and transdifferentiation of zebrafish nsSCs to HCs in the inner ear.

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Deflecting biomineralized crystals attached to vestibular hair cells are necessary for maintaining balance. Zebrafish (Danio rerio) are useful organisms to study these biomineralized crystals called otoliths, as many required genes are homologous to human otoconial development. We sought to identify and characterize the causative gene in a trio of homozygous recessive mutants, no content (nco) and corkscrew (csr), and vanished (vns), which fail to develop otoliths during early ear development.

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Background: Hospitalizations for major depressive disorder (MDD) are a significant burden on patients, their families, and to healthcare systems. This study characterized the prevalence of MDD hospitalizations in the US and described clinical characteristics, treatment patterns, length of stay, costs, and MDD-related hospitalization readmissions.

Methods: A retrospective analysis of the Premier Perspective Hospital Database was conducted using records of hospital admissions for MDD from January 1, 2014 to December 31, 2015.

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Although hair cells are the sensory receptors of the auditory and vestibular systems in the ears of all vertebrates, hair cell properties are different between non-mammalian vertebrates and mammals. To understand the basic biological properties of hair cells from non-mammalian vertebrates, we examined the transcriptome of adult zebrafish auditory and vestibular hair cells. GFP-labeled hair cells were isolated from inner-ear sensory epithelia of a pou4f3 promoter-driven GAP-GFP line of transgenic zebrafish.

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Objective: To evaluate the effects of levomilnacipran extended-release (LVM-ER; 40-120mg/day) on noradrenergic (NA) and anxiety-related symptoms in adults with major depressive disorder (MDD) and explore the relationship between these symptoms and functional impairment.

Methods: Data were pooled from 5 randomized, double-blind, placebo-controlled trials (N=2598). Anxiety and NA Cluster scores were developed by adding selected item scores from the Montgomery-Åsberg Depression Rating Scale (MADRS) and 17-item Hamilton Depression Rating Scale (HAMD).

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The objective of this post-hoc analysis was to investigate the relationship between motivation/energy and functional impairment in patients with major depressive disorder (MDD). Data were taken from a phase 3 trial of levomilnacipran extended-release (ER) in adults with MDD (NCT01034462; N=429) that used the 18-item Motivation and Energy Inventory (MEI) to assess motivation/energy. Two subgroups with lower and higher motivation/energy were defined using baseline MEI total scores (≤28 and >28, respectively).

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Background: Major depressive disorder (MDD) can be challenging to manage due its variable and episodic nature. Post hoc analyses were conducted on five studies (NCT00969709, NCT01377194, NCT00969150, NCT01034462, EudraCT:2006-002404-34) to evaluate the efficacy of levomilnacipran extended-release (ER) in patients with different MDD episode histories.

Methods: Adults with MDD were randomized to double-blind treatment with levomilnacipran ER (40-120mg/d) or placebo.

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Sciatica is generally caused by such well-recognized entities as lumbar disc herniation and degenerative stenosis. A rarely reported alternative cause of lumbar nerve root compression is by distended epidural veins. A case is presented of sciatica produced by such a mechanism, successfully treated by decompressive laminotomy.

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Collective cell migration is a highly regulated morphogenetic movement during embryonic development and cancer invasion that involves the precise orchestration and integration of cell-autonomous mechanisms and environmental signals. Coordinated lateral line primordium migration is controlled by the regulation of chemokine receptors via compartmentalized Wnt/β-catenin and fibroblast growth factor (Fgf) signaling. Analysis of mutations in two exostosin glycosyltransferase genes (extl3 and ext2) revealed that loss of heparan sulfate (HS) chains results in a failure of collective cell migration due to enhanced Fgf ligand diffusion and loss of Fgf signal transduction.

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Background: Otoconia are bio-crystals that couple mechanic forces to the sensory hair cells in the utricle and saccule, a process essential for us to sense linear acceleration and gravity for the purpose of maintaining bodily balance. In fish, structurally similar bio-crystals called otoliths mediate both balance and hearing. Otoconia abnormalities are common and can cause vertigo and imbalance in humans.

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Arterial and venous specification is critical for establishing and maintaining a functioning vascular system, and defects in key arteriovenous signaling pathways including VEGF (vascular endothelial growth factor) lead to congenital arteriopathies. The activities of VEGF, are in part controlled by heparan sulfate (HS) proteoglycans, significant components of the endothelial glycocalyx. The level of 6-O sulfation on HS polysaccharide chains, that mediate the interaction between HS and VEGFA, is edited at the cell surface by the enzyme SULF1.

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Yes-associated protein 65 (YAP) contains multiple protein-protein interaction domains and functions as both a transcriptional co-activator and as a scaffolding protein. Mouse embryos lacking YAP did not survive past embryonic day 8.5 and showed signs of defective yolk sac vasculogenesis, chorioallantoic fusion, and anterior-posterior (A-P) axis elongation.

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Ubiquitously found in the extracellular matrix and attached to the surface of most cells, glycosaminoglycans (GAGs) mediate many intercellular interactions. Originally described in 1889 as the primary carbohydrate in cartilage and then in 1916 as a coagulation inhibitor from liver, various GAGs have since been identified as key regulators of normal physiology. GAGs are critical mediators of differentiation, migration, tissue morphogenesis, and organogenesis during embryonic development.

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Forward genetic screens with ENU (N-ethyl-N-nitrosourea) mutagenesis can facilitate gene discovery, but mutation identification is often difficult. We present the first study in which an ENU-induced mutation was identified by massively parallel DNA sequencing. This mutation causes heterotaxy and complex congenital heart defects and was mapped to a 2.

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Heparan sulfate (HS) binds numerous extracellular ligands, including cell-cell signaling molecules and their signal-transducing receptors. Ligand binding sites in HS have specific sulfation patterns; and several observations suggest that the HS sulfation pattern is the same for every HS chain that a cell synthesizes, regardless of the core protein to which it is attached. Nonetheless, virtually every Drosophila, zebrafish, Xenopus, and mouse that lacks a specific HS core protein has a mutant phenotype, even though other HS core proteins are expressed in the affected cells.

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Currently, most basic and clinical research on depression is focused on either central serotonergic, noradrenergic, or dopaminergic neurotransmission as affected by various etiological and predisposing factors. Recent evidence suggests that there is another system that consists of a subset of brain alpha(1B)-adrenoceptors innervated primarily by brain epinephrine (EPI) that potentially modulates the above three monoamine systems in parallel and plays a critical role in depression. The present review covers the evidence for this system and includes findings that brain alpha(1)-adrenoceptors are instrumental in behavioral activation, are located near the major monoamine cell groups or target areas, receive EPI as their neurotransmitter, are impaired or inhibited in depressed patients or after stress in animal models, and are restored by a number of antidepressants.

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The role of brain epinephrine (EPI) in the regulation of motor activity and movement in mice was examined. Blockade of EPI synthesis with i.p.

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The transmembrane proteoglycan syndecan-2 cell nonautonomously regulates left-right (LR) development in migrating mesoderm by an unknown mechanism, leading to LR asymmetric gene expression and LR orientation of the heart and gut. Here, we demonstrate that protein kinase C gamma (PKCgamma) mediates phosphorylation of the cytoplasmic domain of syndecan-2 in right, but not left, animal cap ectodermal cells. Notably, both phosphorylation states of syndecan-2 are obligatory for normal LR development, with PKCgamma-dependent phosphorylated syndecan-2 in right ectodermal cells and nonphosphorylated syndecan-2 in left cells.

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Background: In this study, we investigated the mechanism(s) by which delta opioids induce their potent activation of extracellular signal-regulated protein kinases (ERKs) in different cell lines expressing the cloned delta-opioid receptor (delta-OR). While it has been known for some time that OR stimulation leads to the phosphorylation of both ERK isoforms, the exact progression of events has remained elusive.

Results: Our results indicate that the transphosphorylation of an endogenous epidermal growth factor receptor (EGFR) in the human embryonic kidney (HEK-293) cell line does not occur when co-expressed delta-ORs are stimulated by the delta-opioid agonist, D-Ser-Leu-enkephalin-Thr (DSLET).

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