Production of bacterial outer membrane vesicles as vaccine platform

Bacterial outer membrane vesicles (OMVs) are non-infectious but highly immunogenic particles. These vesicles are used as vaccines against the disease of the source bacteria. Fascinatingly, the addition of heterologous antigens to these vesicles creates a versatile vaccine platform. Such a platform can be used as an alternative to subunit vaccines, during infectious disease outbreaks or for the development of vaccines against pathogens that require high containment. A unique aspect of this platform is the reusability of the production process for many different vaccines. This in turn could reduce the time to market for new vaccines significantly. We designed a heterologous OMV vaccine concept for Lyme disease based on spontaneous released OMVs from Neisseria meningitidis that express the Outer surface protein A (OspA) of Borrelia burgdorferi on the surface. The productivity of spontaneously released OMVs was improved by the introduction of oxidative stress to the bacterial culture. Increased dissolved oxygen concentrations during cultivation showed to be an excellent process parameter for enhanced release of OMVs, while the bacterial culture remains viable. This presentation will cover the development of the OMV-based vaccine platform and the impact of changes in the upstream process on the downstream process of the investigational OMV-based Lyme disease vaccine. Please click Additional Files below to see the full abstract

Conditioning bounds for traveltime tomography in layered media

This paper revisits the problem of recovering a smooth, isotropic, layered wave speed profile from surface traveltime information. While it is classic knowledge that the diving (refracted) rays classically determine the wave speed in a weakly well-posed fashion via the Abel transform, we show in this paper that traveltimes of reflected rays do not contain enough information to recover the medium in a well-posed manner, regardless of the discretization. The counterpart of the Abel transform in the case of reflected rays is a Fredholm kernel of the first kind which is shown to have singular values that decay at least root-exponentially. Kinematically equivalent media are characterized in terms of a sequence of matching moments. This severe conditioning issue comes on top of the well-known rearrangement ambiguity due to low velocity zones. Numerical experiments in an ideal scenario show that a waveform-based model inversion code fits data accurately while converging to the wrong wave speed profile

Aerodynamic investigations of ventilated brake discs.

The heat dissipation and performance of a ventilated brake disc strongly depends on the aerodynamic characteristics of the flow through the rotor passages. The aim of this investigation was to provide an improved understanding of ventilated brake rotor flow phenomena, with a view to improving heat dissipation, as well as providing a measurement data set for validation of computational fluid dynamics methods. The flow fields at the exit of four different brake rotor geometries, rotated in free air, were measured using a five-hole pressure probe and a hot-wire anemometry system. The principal measurements were taken using two-component hot-wire techniques and were used to determine mean and unsteady flow characteristics at the exit of the brake rotors. Using phase-locked data processing, it was possible to reveal the spatial and temporal flow variation within individual rotor passages. The effects of disc geometry and rotational speed on the mean flow, passage turbulence intensity, and mass flow were determined. The rotor exit jet and wake flow were clearly observed as characterized by the passage geometry as well as definite regions of high and low turbulence. The aerodynamic flow characteristics were found to be reasonably independent of rotational speed but highly dependent upon rotor geometry

Wartenberg’s migrant sensory neuritis: a prospective follow-up study

Migrant sensory neuropathy (Wartenberg’s migrant sensory neuritis) is characterized by sudden numbness in the distribution of one or multiple cutaneous nerves. To study disease course and outcome, we prospectively followed 12 patients who presented to our tertiary referral neuromuscular outpatient clinic between January 2003 and January 2004. Medical history, neurological, laboratory and electrophysiological examinations were obtained from all patients. All patients were reviewed a second time in 2007, and five had a follow-up electrophysiological examination. At the first visit, 50% described an episode of stretching preceding the sensory complaints. All but three described pain in the affected area before or concomitant with sensory loss. At clinical examination a median of six skin areas were affected, and in 75% this could be confirmed by nerve conduction studies in at least one nerve. Forty-two percent had involvement of the trigeminal nerve. After a mean disease duration of 7.5 years, three patients reported a complete disappearance of sensory complaints and five that the pain had disappeared, but numbness remained. Three patients still had both painful and numb sensory deficits. One patient developed a distal symmetric sensory polyneuropathy. In conclusion, Wartenberg’s sensory neuritis is a distinct, exclusively sensory, neuropathy, marked by pain preceding numbness in affected nerves. An episode of stretching preceding pain is not necessary for the diagnosis. Wartenberg’s sensory neuritis often retains its spotty, exclusively sensory characteristics after long term follow-up

Murine GRPR and Stathmin Control in Opposite Directions both Cued Fear Extinction and Neural Activities of the Amygdala and Prefrontal Cortex

Extinction is an integral part of normal healthy fear responses, while it is compromised in several fear-related mental conditions in humans, such as post-traumatic stress disorder (PTSD). Although much research has recently been focused on fear extinction, its molecular and cellular underpinnings are still unclear. The development of animal models for extinction will greatly enhance our approaches to studying its neural circuits and the mechanisms involved. Here, we describe two gene-knockout mouse lines, one with impaired and another with enhanced extinction of learned fear. These mutant mice are based on fear memory-related genes, stathmin and gastrin-releasing peptide receptor (GRPR). Remarkably, both mutant lines showed changes in fear extinction to the cue but not to the context. We performed indirect imaging of neuronal activity on the second day of cued extinction, using immediate-early gene c-Fos. GRPR knockout mice extinguished slower (impaired extinction) than wildtype mice, which was accompanied by an increase in c-Fos activity in the basolateral amygdala and a decrease in the prefrontal cortex. By contrast, stathmin knockout mice extinguished faster (enhanced extinction) and showed a decrease in c-Fos activity in the basolateral amygdala and an increase in the prefrontal cortex. At the same time, c-Fos activity in the dentate gyrus was increased in both mutant lines. These experiments provide genetic evidence that the balance between neuronal activities of the amygdala and prefrontal cortex defines an impairment or facilitation of extinction to the cue while the hippocampus is involved in the context-specificity of extinction

Feasibility of neonatal dried blood spot retrieval amid evolving state policies (2009-2010): a Children's Oncology Group study

Dried blood spots (DBS) are collected uniformly from US newborns to test for metabolic and other disorders. Because evidence exists for prenatal origins of some diseases, DBS may provide unique prenatal exposure records. Some states retain residual DBS and permit their use in aetiological studies. The primary study aim was to assess the feasibility of obtaining residual DBS from state newborn screening programmes for paediatric and adolescent cancer patients nationwide with parental/subject consent/assent. Families of leukaemia and lymphoma patients aged ≤21 years diagnosed from 1998 to 2007 at randomly selected Children's Oncology Group institutions across the US were questioned (n = 947). Parents/guardians and patients aged ≥18 years were asked to release DBS to investigators in spring 2009. DBS were then requested from states. Overall, 299 families (32%) released DBS. Consenting/assenting patients were born in 39 US states and 46 DBS were obtained from five states; 124 DBS were unobtainable because patients were born prior to dates of state retention. State policies are rapidly evolving and there is ongoing discussion regarding DBS storage and secondary research uses. Currently, population-based DBS studies can be conducted in a limited number of states; fortunately, many have large populations to provide reasonably sized paediatric subject groups