Academic literature on the topic 'Microtubules – Research – Methodology'

Rational drug design and in vitro pharmacology profiling constitute the gold standard in drug development pipelines. Problems arise, however, because this process is often difficult due to limited information regarding the complete identification of a molecule’s biological activities. The increasing affordability of genome-wide next-generation technologies now provides an excellent opportunity to understand a compound’s diverse effects on gene regulation. Here, we used an unbiased approach in lung and colon cancer cell lines to identify the early transcriptomic signatures of C-1305 cytotoxicity that highlight the novel pathways responsible for its biological activity. Our results demonstrate that C-1305 promotes direct microtubule stabilization as a part of its mechanism of action that leads to apoptosis. Furthermore, we show that C-1305 promotes G2 cell cycle arrest by modulating gene expression. The results indicate that C-1305 is the first microtubule stabilizing agent that also is a topoisomerase II inhibitor. This study provides a novel approach and methodology for delineating the antitumor mechanisms of other putative anticancer drug candidates.

The nervous system is the part of our body that plays critical roles in the coordination of actions and sensory information as well as communication between different body parts through electrical signal transmissions. Current studies have shown that patients are likely to experience a functional loss if they have to go through a nerve repair for >15 mm lesion. The ideal treatment methodology is autologous nerve transplant, but numerous problems lie in this treatment method, such as lack of harvesting sites. Therefore, researchers are attempting to fabricate alternatives for nerve regeneration, and nerve conduit is one of the potential alternatives for nerve regeneration. In this study, we fabricated polyurethane/polydopamine/extracellular matrix (PU/PDA/ECM) nerve conduits using digital light processing (DLP) technology and assessed for its physical properties, biodegradability, cytocompatibility, neural related growth factor, and proteins secretion and expression and its potential in allowing cellular adhesion and proliferation. It was reported that PU/PDA/ECM nerve conduits were more hydrophilic and allowed enhanced cellular adhesion, proliferation, expression, and secretion of neural-related proteins (collagen I and laminin) and also enhanced expression of neurogenic proteins, such as nestin and microtubule-associated protein 2 (MAP2). In addition, PU/PDA/ECM nerve conduits were reported to be non-cytotoxic, had sustained biodegradability, and had similar physical characteristics as PU conduits. Therefore, we believed that PU/PDA/ECM nerve conduits could be a potential candidate for future nerve-related research or clinical applications.

Purpose The purpose of this paper is to compare the fluid dynamic performance of two Aqueous Humor (AH) ocular drainage devices, the SOLX® Gold Micro Shunt (GMS) and the novel Silicon Shunt Device (SSD), implanted by surgeons in human eyes to reduce the IntraOcular Pressure towards physiological values, by draining the AH from the Anterior Chamber to the Suprachoroidal Space, to cure eyes with glaucoma. Design/methodology/approach The generalized porous medium model is solved to simulate the AH flow through the two ocular drainage devices and the surrounding porous tissues of the eye. Findings In the GMS, probable stagnation regions have been found, due to the very small AH velocity values inside the device and to the surrounding tissues, creating possible blockage and malfunction of the device. The simple microtubular geometry of the novel SSD allows to have a regular AH flow and to choose shunts with different diameters and/or with the presence of radial holes, based on patient needs, with consequent reduction of post-operative complications. Research limitations/implications The present model will be further developed taking into account the insertion of the present drainage devices inside the anterior section of the eye. The present results show the comparative fluid dynamic performance of the two shunts considered, and can be useful for surgeons to choose the adequate shunt, based on the required AH flow rate for a specific patient. Practical implications The present numerical approach, employing the generalized porous medium model, represents a useful tool to study the fluid dynamics of ocular drainage devices and to design these shunts, to reduce post-operative complications. Originality/value The generalized porous medium model is here applied for the first time to simulate the interaction of ocular drainage devices with the surrounding porous tissues of the eye.

Abstract Abstract 2579 Poster Board II-556 Silent cerebral infarction (SCI) is part of a spectrum of cerebrovascular disease, occurs in approximately 22% of children with sickle cell disease (SCD) and is associated with decreased cognitive function. While several plasma biomarkers have been shown to be elevated in acute stroke, to our knowledge none have been evaluated in SCD or SCI. The aim of this study was to develop a reliable pipeline to identify low abundance plasma proteins that correlate with SCI in patients with SCD. We used a proteomic discovery approach involving three sequential separation steps in order to compare the plasma proteomes in a discovery set of 15 children with SCD (7 children with SCI and 8 children without SCI). Baseline steady state plasma samples obtained from the Silent Infarct Transfusion (SIT) Trial Biologic Repository were matched for age and WBC. In the first dimension, hemoglobin was depleted with nickel-nitrilotriacetic acid (Ni-NTA). Subsequently, second dimension separation and enrichment was achieved by immunoaffinity depletion of the 12 most abundant proteins (ProteomeLab IgY-12 LC10) followed by third dimension separation by reverse phase liquid chromatography fractionation (RPLC) using a C18 column and a linear acetonitrile gradient. Collected fractions were subjected to tryptic digestion and analyzed using label-free quantification on a LTQ-Orbitrap (Thermo) mass spectrometer. The MS/MS data were analyzed using the Proteomics Analyzer Software System (PASS) version 4.0.10 (Integrated Analysis Inc, Bethesda, MD) with X! Tandem searches (www.thegpm.org; version 2008.12.01) using the human IPI database. Identified proteins were compared to databases of brain specific and brain enriched proteins to identify candidate biomarker proteins for SCI. After hemoglobin depletion, 71% of total protein was removed. On average, protein recovery after the LC-12 column was 4% of the total Ni-NTA depleted protein. Of the 9800 proteins that were identified in the plasma proteome of children with SCD, 23 were brain specific proteins. Evaluation of the relative abundance by spectral counts (SC) revealed 3 brain-related proteins that were over-represented in patients with SCI: microtubule-associated protein tau (a neurofibrillary tangle protein implicated in Alzheimer disease, frontotemporal dementia and parkinsonism), neuroligin-3 (a neuronal cell surface protein proposed to be involved in cell-cell-interactions via binding to beta-neurexins and implicated in autism and Asperger syndrome), and nucleosome-remodeling factor subunit BPTF (a histone-binding component of nucleosome-remodeling factor that is abundantly expressed in the fetal brain and re-expressed in neurodegenerative diseases). Reticulon-4, a potent neurite growth inhibitor involved in the restriction of axonal regeneration after injury, was under-represented in patients with SCI. After depletion of hemoglobin and other high abundant proteins, we were able to develop a database of plasma proteins in children with SCD and to identify brain specific proteins as potential surrogate markers of brain injury. These markers may be implicated in the pathophysiology of SCI. Although validation studies are necessary to determine the relevance of these candidate biomarkers in SCI and SCD, our methodology appears to be a practical approach to proteomic discovery in patients with hemolytic anemia. Disclosures: Casella: Boehringer Ingelheim: Honoraria, Research Funding, Travel funding.

Abstract Background Current epidemiological studies have examined the associations between moderate and severe traumatic brain injury (TBI) and their risks of developing neurodegenerative diseases. Concussion, also known as mild TBI (mTBI), is however quite distinct from moderate or severe TBIs. Only few studies in this burgeoning area have examined concussion—especially repetitive episodes—and neurodegenerative diseases. Thus, no definite relationship has been established between them. Objectives This review will discuss the available literatures linking concussion and amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease (AD). Materials and Methods Given the complexity of this subject, a realist review methodology was selected which includes clarifying the scope and developing a theoretical framework, developing a search strategy, selection and appraisal, data extraction, and synthesis. A detailed literature matrix was set out in order to get relevant and recent findings on this topic. Results Presently, there is no objective clinical test for the diagnosis of concussion because the features are less obvious on physical examination. Absence of an objective test in diagnosing concussion sometimes leads to skepticism when confirming the presence or absence of concussion. Intriguingly, several possible explanations have been proposed in the pathological mechanisms that lead to the development of some neurodegenerative disorders (such as ALS and AD) and concussion but the two major events are deposition of tau proteins (abnormal microtubule proteins) and neuroinflammation, which ranges from glutamate excitotoxicity pathways and inflammatory pathways (which leads to a rise in the metabolic demands of microglia cells and neurons), to mitochondrial function via the oxidative pathways. Conclusion mTBI constitutes majority of brain injuries. However, studies have focused mostly on moderate-to-severe TBI as highlighted above with inconclusive and paucity of studies linking concussion and neurodegenerative disorders. Although, it is highly probable that repetitive concussion (mTBI) and subconcussive head injuries may be risk factors for ALS) and AD from this review. It will be imperative therefore to conduct more research with a focus on mTBI and its association with ALS and AD.

Microtubule targeting agents (MTAs) are chemotherapeutics commonly used in the treatment of breast, ovarian, lung, and lymphoma cancers. There are two main classes of MTAs based upon their effects on microtubule stability. The two classes are the destabilizing agents, which include the drug vincristine, and the stabilizing agents, which include paclitaxel and epothilone B. These drugs are highly effective antineoplastics, but their use is often accompanied by several side effects, one of which is peripheral neuropathy. Peripheral neuropathy can be characterized by burning pain, tingling, loss of proprioception, or numbness in the hands and feet. In some patients, the MTA-induced peripheral neuropathy is debilitating and dose-limiting; however, there are no effective prevention strategies or treatment options for peripheral neuropathy as the mechanisms mediating this side effect are unknown. The goal of this work was to investigate MTA-induced effects on neuronal activity and morphology in order to elucidate the underlying mechanisms involved in the development of MTA-induced peripheral neuropathy. As an indicator of sensory neuronal activity, the basal and stimulated release of the putative nociceptive peptide, calcitonin gene-related peptide (CGRP), was measured from sensory neurons in culture after exposure to the MTAs paclitaxel, epothilone B, and vincristine. Neurite length and branching were also measured in sensory neuronal cultures after treatment with these MTAs. The results described in this thesis demonstrate that MTAs alter the stimulated release of CGRP from sensory neurons in differential ways depending on the MTA agent employed, the CGRP evoking-stimulus used, the concentration of the MTA agent, the duration of exposure to the MTA agent, and the presence of NGF. It was also observed that MTA agents decrease neurite length and branching, independent of the concentration of NGF in the culture media. Thus, this thesis describes MTA-induced alterations of sensory neuronal sensitivity and neurite morphology and begins to elucidate the underlying mechanisms involved in MTA-induced alterations of sensory neurons. These findings will undoubtedly be used to help elucidate the mechanisms underlying MTA-induced peripheral neuropathy.

Indiana University-Purdue University Indianapolis (IUPUI)
Approximately 2.8% of the world population is currently infected with hepatitis C virus (HCV). Neutralizing antibodies (nAbs) are often generated in chronic hepatitis C patients yet fail to control the infection. In the first two chapters of this study, we focused on two alternative routes of HCV transmission, which may contribute to HCV’s immune evasion and establishment of chronic infection. HCV was transmitted via a cell-cell contact-mediated (CCCM) route and in the form of exosomes. Formation of HCV infection foci resulted from CCCM HCV transfer and was cell density-dependent. Moreover, CCCM HCV transfer occurred rapidly, involved all four known HCV receptors and intact actin cytoskeleton, and led to productive HCV infection. Furthermore, live cell imaging revealed the temporal and spatial details of the transfer process. Lastly, HCV from HCV-infected hepatocytes and patient plasma occurred in both exosome-free and exosome-associated forms and the exosome-associated HCV remained infectious, even though HCV infection did not significantly alter exosome secretion. In the third chapter, we characterized HCV interaction with astrocytes, one of the putative HCV target cells in the brain. HCV infection causes the central nervous system (CNS) abnormalities in more than 50% of chronically infected subjects but the underlying mechanisms are largely unknown. We showed that primary human astrocytes (PHA) were very inefficiently infected by HCV, either in the free virus form or through cell-cell contact. PHA expressed all known HCV receptors but failed to support HCV entry. HCV IRES-mediated translation was functional in PHA and further enhanced by miR122 expression. Nevertheless, PHA did not support HCV replication regardless of miR122 expression. To our great surprise, HCV exposure induced robust IL-18 expression in PHA and exhibited direct neurotoxicity. In summary, we showed that CCCM HCV transfer and exosome-mediated HCV infection constituted important routes for HCV infection and dissemination and that astrocytes did not support productive HCV infection and replication, but HCV interactions with astrocytes and neurons alone might be sufficient to cause CNS dysfunction. These findings provide new insights into HCV infection of hepatocytes and astrocytes and shall aid in the development of new and effective strategies for preventing and treating HCV infection.

As the ability to manipulate materials and components at the nanoscale continues to grow, it will become increasingly critical to understand the dynamic interactions that occur among multiple components. For example, the dynamic interactions among proteins (i.e., nanoscale molecular machines) lead to complex, emergent behaviors such as photosynthesis, self-repair, and cell division. Recently, the research group at Sandia National Labs and The Center for Integrated Nanotechnologies (CINT), headed by George Bachand, has developed a molecular transport system capable of transporting and manipulating a wide range of nanoscale components. This system is based on the kinesin motor molecule and cytoskeletal filament microtubules (MTs), in which the kinesin are mounted to a substrate in an inverted fashion, and capable of binding and transporting the MTs across a surface as a molecular shuttle. In the presence of ATP, the kinesins are capable of generating ∼40 pN·nm of work, and transporting MTs along the substrate at velocities of ∼1 micro-m/sec. The MTs may also serve as a transport platform for various inorganic and biological nanoparticles. During transport, the cargo is transferred, via elastic collisions, from one MT to another or to where two MT carry a single cargo. Bending of the MT and various other elasto-dynamic phenomena such as particle ejection, MT sticking, etc are observed via fluorescence microscopy. The interaction observed by the Bachand team is not unlike the interaction of macroscale devices. The kinesin provide motivation to the MT via a hand-over-hand ratchet like motion driven by ATP hydrolysis. As the kinesin motor domains come into contact with and bind the MT, it is not inconceivable to think of this action from the framework of instantly applied constraints in a manner similar to the macroscopic action of devices coming into and out of constrained interaction. The hypothesis of our work is that the elasto-dynamic phenomenon observed can be modeled with the tools of multiple body dynamics modeling. The modeling perspective is based on the lead author’s hybrid parameter multiple body dynamics modeling methodology. This technique is a variational approach based on the projection methods of Gibbs-Appell. The constrained interaction through contact and impact are modeled with the idea of instantly applied non-holonomic constraints, where the interactions on the boundaries and in the domain of elastic continua are modeled via projections of the d’Alembert force deficit along conjugate directions generated via so called pseudo-generalized-speeds. In this paper we present motivation for our approach, the underlying modeling theory, and current results of our efforts at understanding the kinesin/MT shuttle system interaction.