High-throughput Titration of Luciferase-expressing Recombinant Viruses

Standard plaque assays to determine infectious viral titers can be time consuming, are not amenable to a high volume of samples, and cannot be done with ...

Ottawa Hospital Research Institute

University of Ottawa

The I-tetraplex building block: rational design and controlled fabrication of robust 1D DNA scaffolds through non-Watson-Crick interactions.

It's a trap! DNA polyhedra formed through molecular self-assembly may function as nanocapsules for the targeted delivery of encapsulated entities. This functional aspect was demonstrated for the most complex DNA-based platonic solid: During the stepwise amalgamation of discrete polyhedra to form icosahedra, gold nanoparticles (GNPs) were encapsulated from solution (see illustration and TEM image of icosahedral cages containing GNPs).

Icosahedral DNA nanocapsules by modular assembly.

5,5-Acetamidomethyl-5-methylimidazolidine-2,4-dione shows antimicrobial activity against bacteria at millimolar concentrations well above its critical micellar concentration (cmc). Two-dimensional surface properties were investigated using Langmuir Film Balance to understand the membrane-active nature and nanomaterial behavior of this hydantoin derivative. Hydantoin forms an expanded nanofilm at air-water interface. The maximum limiting surface area (A(0)) and collapse pressure (pi(c)) are dependent on hydantoin concentration. Hydantoin undergoes a change in orientation at the interface, in the pressure region 2.5 and 7.5 mNm(-1), corresponding to surface areas 51-15 and 41-12A(2)molecule(-1), respectively. A large collapse pressure (pi(c)) in LB film indicates a role for hydrophobic interactions in the self-assembly of hydantoin. Surface areas computed using Connolly method, are in good agreement with the experimental results. Monolayer studies suggest a dispersed state for hydantoin when its concentration is below cmc, suggesting a mechanism for the observed bacteriostatic activity of hydantoin. In the present study, it has been found for the first time that the minimum inhibitory concentration (MIC) of the hydantoin is very close to its cmc.

Two-dimensional surface properties of an antimicrobial hydantoin at the air-water interface: an experimental and theoretical study.

The function of the auditory cortex is dynamic. Although auditory cortical plasticity can be induced through various approaches such as learning, experience and sensory deprivation, a common property is the frequency-specificity; the change in neuronal receptive field or functional maps is highly specific to the frequency content of the acquired sound. This unique property suggests that precise frequency information must be relayed to the auditory cortex. It is well known that the auditory thalamocortical pathway is the only neural substrate that sends precise frequency information to the auditory cortex. This review addresses the impact of the auditory thalamocortical system on cortical plasticity. The frequency-specificity of auditory cortical plasticity and the tonotopic features of the auditory thalamocortical system are briefly presented. A discussion of the decisive role of thalamocortical system follows. After an exploration of a possible synaptic mechanism, a thalamocortical model is proposed to better interpret the neural mechanisms underlying frequency-specific plasticity of the auditory cortex.

Contributions of the thalamocortical system towards sound-specific auditory plasticity.

Localised ascending aortic dissection managed conservatively.

A Gram-stain-negative, strictly aerobic, slightly halophilic, non-motile and rod-shaped bacterial strain, designated P2E16(T), was isolated from mangrove (Avicennia marina) rhizosphere, collected at Devipattinam mangroves, Tamil Nadu, India. Strain P2E16(T) grew optimally at pH 7.0-8.0, at 25-28 °C and in the presence of 2-3% (w/v) NaCl. 16S rRNA gene analysis showed that strain P2E16(T) was phylogenetically closely related to the genus Zunongwangia, with Zunongwangia profunda SM-A87(T) as the closest related type strain (98.2% 16S rRNA gene sequence similarity) and less than 93% 16S rRNA gene sequence similarity to all other members of the family Flavobacteriaceae. Strain P2E16(T) contained MK-6 as the major respiratory quinone, phosphatidylethanolamine as the predominant polar lipid and iso-C(15 : 0) (17.8%), iso-C(17 : 0) 3-OH (15.1%), C(15 : 0) (12.8%), iso-C(17 : 1)ω9c (9.8%), iso-C(15 : 1) G (9.0%), and summed feature 3 (comprising C(16 : 1)ω7c and/or iso-C(15 : 0) 2-OH; 7.1%) as the major fatty acids. The DNA G+C content was 34.3 mol%. Differential phenotypic properties, together with the phylogenetic distinctiveness and low DNA-DNA relatedness demonstrated that strain P2E16(T) was distinct from the type strain of Zunongwangia profunda. On the basis of these presented data, strain P2E16(T) is considered to represent a novel species of the genus Zunongwangia, for which the name Zunongwangia mangrovi sp. nov. is proposed. The type strain is P2E16(T) ( = DSM 24499(T) = LMG 26237(T) = KCTC 23496(T)). An emended description of the genus Zunongwangia is also provided.

Zunongwangia mangrovi sp. nov., isolated from mangrove (Avicennia marina) rhizosphere, and emended description of the genus Zunongwangia.

The spliceosome is a dynamic ribonucleoprotein (RNP) machine that catalyzes the removal of introns during the two transesterification steps of eukaryotic pre-mRNA splicing. Here we used single-molecule fluorescence resonance energy transfer to monitor the distance of the 5' splice site (5' SS) and branch point (BP) of pre-mRNA in affinity-purified spliceosomes stalled by a mutation in the DExD/H-box helicase Prp2 immediately before the first splicing step. Addition of recombinant Prp2 together with NTP and protein cofactor Spp2 rearranges the spliceosome-substrate complex to reversibly explore conformations with proximal 5' SS and BP that accommodate chemistry. Addition of Cwc25, a small heat-stable splicing factor, then strongly biases this equilibrium toward the proximal conformation, promoting efficient first-step splicing. The spliceosome thus functions as a biased Brownian ratchet machine where a helicase unlocks thermal fluctuations subsequently rectified by a cofactor 'pawl', a principle possibly widespread among the many helicase-driven RNPs.

Biased Brownian ratcheting leads to pre-mRNA remodeling and capture prior to first-step splicing.

Thymomas rarely present with chest pain due to hemorrhage. This could cause shortness of breath if it ruptures into the pleural space, and is best managed surgically. We describe the case of an 83-year-old woman who presented with such symptoms. Computed tomography showed a ruptured mediastinal mass with pleural effusion. She was managed successfully by thoracotomy with excision of the mass and drainage of the effusion. Histopathology revealed a ruptured thymoma with infarction and necrosis.

Ruptured thymoma managed via thoracotomy.

The diagnosis of melioidosis can be difficult, and it is frequently described as "the great mimicker". We report a case of thoracic melioidosis presenting as a mediastinal mass with impending superior vena cava obstruction. With the presumptive diagnosis of mediastinal tumor, the patient underwent surgery for tissue sampling, and a purulent collection was found. The clinical syndromes of melioidosis and the diagnostic dilemma are discussed.

Thoracic melioidosis: A diagnostic dilemma.

Oncolytic viruses (OVs) not only kill cancer cells by direct lysis but also generate a significant anti-tumor immune response that allows for prolonged cancer control and in some cases cures. How to best stimulate this effect is a subject of intense investigation in the OV field. While pharmacological manipulation of the cellular innate anti-viral immune response has been shown by several groups to improve viral oncolysis and spread, it is increasingly clear that pharmacological agents can also impact the anti-tumor immune response generated by OVs and related tumor vaccination strategies. This review covers recent progress in using pharmacological agents to improve the activity of OVs and their ability to generate robust anti-tumor immune responses.

Ramya Krishnan

Center for Innovative Cancer Research

Ottawa Hospital Research Institute

High-throughput Titration of Luciferase-expressing Recombinant Viruses

Ramya Krishnan

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Ottawa Hospital Research Institute

High-throughput Titration of Luciferase-expressing Recombinant Viruses

Center for Innovative Cancer Research