Optical trapping with "on-demand" two-photon luminescence using Cr:LiSAF laser with optically addressed saturable Bragg reflector

We demonstrate a diode-pumped Cr:LiSAF laser with controllable and reliable fast switching between its continuous-wave and mode-locked states of operation using an optically-addressed semiconductor Bragg reflector, permitting dyed microspheres to be continuously trapped and monitored using a standard microscope imaging and on-demand two-photon-excited luminescence techniques

Development of Multigene Expression Signature Maps at the Protein Level from Digitized Immunohistochemistry Slides

Molecular classification of diseases based on multigene expression signatures is increasingly used for diagnosis, prognosis, and prediction of response to therapy. Immunohistochemistry (IHC) is an optimal method for validating expression signatures obtained using high-throughput genomics techniques since IHC allows a pathologist to examine gene expression at the protein level within the context of histologically interpretable tissue sections. Additionally, validated IHC assays may be readily implemented as clinical tests since IHC is performed on routinely processed clinical tissue samples. However, methods have not been available for automated n-gene expression profiling at the protein level using IHC data. We have developed methods to compute expression level maps (signature maps) of multiple genes from IHC data digitized on a commercial whole slide imaging system. Areas of cancer for these expression level maps are defined by a pathologist on adjacent, co-registered H&E slides, allowing assessment of IHC statistics and heterogeneity within the diseased tissue. This novel way of representing multiple IHC assays as signature maps will allow the development of n-gene expression profiling databases in three dimensions throughout virtual whole organ reconstructions

Making the most of interference : speckle metrology and its application to cold atoms

Speckle patterns result from the interference of multiple reflections in disordered media. This is regarded as a randomization process which destroys information contained within the initial light beam and is deleterious to many optical systems. Indeed, many engineers study speckle to remove its effect. Intriguingly however, the processes that produce the speckle are entirely linear, and there is growing recognition that this complex pattern is rich in useful information on both the incident laser source and the environment, with startling potential uses. We will demonstrate our recent results [1], which show that the speckle pattern produced by light propagation in an integrating sphere can be used as a sensitive wavemeter, with a resolution below 1fm. Moreover, this can be used to stabilize the wavelength of a laser on a timescale and to a stability applicable for laser cooling of cold atoms. Reference: [1] N. K. Metzger, et al., “Harnessing speckle for a sub-femtometre resolved broadband wavemeter and laser stabilization”, Nature Communications 8, 15610 (2017)PostprintNon peer reviewe

The Way Cyber Physical Systems Will Revolutionise Maintenance

30th Conference on Condition Monitoring and Diagnostic Engineering Management (COMADEM 2017). 10 to 13, Jul, 2017. Preston, United Kingdom.The way maintenance is carried out is altering rapidly. The introduction of Cyber Physical Systems (CPS) and cloud technologies are providing new technological possibilities that change dramatically the way it is possible to follow production machinery and the necessity to carry out maintenance. In the near future, the number of machines that can be followed from remoteness will explode. At the same time, it will be conceivable to carry out local diagnosis and prognosis that support the adaptation of Condition Based Maintenance (CBM) i.e. financial optimisation can drive the decision whether a machine needs maintenance or not. Further to this, the cloud technology allows to accumulate relevant data from numerous sources that can be used for further improvement of the maintenance practices. The paper goes through the new technologies that have been mentioned above and how they can be benefitted from in practise.info:eu-repo/semantics/publishedVersio

Mucus detachment by host metalloprotease meprin \beta requires shedding of its inactive pro-form, which is abrogated by the pathogenic protease RgpB

The host metalloprotease meprin β is required for mucin 2 (MUC2) cleavage, which drives intestinal mucus detachment and prevents bacterial overgrowth. To gain access to the cleavage site in MUC2, meprin β must be proteolytically shed from epithelial cells. Hence, regulation of meprin β shedding and activation is important for physiological and pathophysiological conditions. Here, we demonstrate that meprin β activation and shedding are mutually exclusive events. Employing ex vivo small intestinal organoid and cell culture experiments, we found that ADAM-mediated shedding is restricted to the inactive pro-form of meprin β and is completely inhibited upon its conversion to the active form at the cell surface. This strict regulation of meprin β activity can be overridden by pathogens, as demonstrated for the bacterial protease Arg-gingipain (RgpB). This secreted cysteine protease potently converts membrane-bound meprin β into its active form, impairing meprin β shedding and its function as a mucus-detaching protease

Robust and Fast Whole Brain Mapping of the RF Transmit Field B1 at 7T

In-vivo whole brain mapping of the radio frequency transmit field B1+ is a key aspect of recent method developments in ultra high field MRI. We present an optimized method for fast and robust in-vivo whole-brain B1+ mapping at 7T. The method is based on the acquisition of stimulated and spin echo 3D EPI images and was originally developed at 3T. We further optimized the method for use at 7T. Our optimization significantly improved the robustness of the method against large B1+ deviations and off-resonance effects present at 7T. The mean accuracy and precision of the optimized method across the brain was high with a bias less than 2.6 percent unit (p.u.) and random error less than 0.7 p.u. respectively

Mutant huntingtin impairs neurodevelopment in human brain organoids through CHCHD2-mediated neurometabolic failure

27 p.-7 fig.Expansion of the glutamine tract (poly-Q) in the protein huntingtin (HTT) causes the neurodegenerative disorder Huntington's disease (HD). Emerging evidence suggests that mutant HTT (mHTT) disrupts brain development. To gain mechanistic insights into the neurodevelopmental impact of human mHTT, we engineered male induced pluripotent stem cells to introduce a biallelic or monoallelic mutant 70Q expansion or to remove the poly-Q tract of HTT. The introduction of a 70Q mutation caused aberrant development of cerebral organoids with loss of neural progenitor organization. The early neurodevelopmental signature of mHTT highlighted the dysregulation of the protein coiled-coil-helix-coiled-coil-helix domain containing 2 (CHCHD2), a transcription factor involved in mitochondrial integrated stress response. CHCHD2 repression was associated with abnormal mitochondrial morpho-dynamics that was reverted upon overexpression of CHCHD2. Removing the poly-Q tract from HTT normalized CHCHD2 levels and corrected key mitochondrial defects. Hence, mHTT-mediated disruption of human neurodevelopment is paralleled by aberrant neurometabolic programming mediated by dysregulation of CHCHD2, which could then serve as an early interventional target for HD.We acknowledge support from the Deutsche Forschungsgemeinschaft (DFG)(PR1527/5-1 to A.P., RTG 2155 ProMoAge to H.O. and L.A.M.K., SFB167 B07 to J.P., RU2795: “Synapses under stress”: PR-1527/6-1 to A.P. and AN-1440/4-1 to R.A.), the Berlin Institute of Health (BIH) (to S.D., J.P., R.K., and A.P.),the Bundesministerium für Bildung und Forschung (BMBF) (AZ. 031L0211 and 01GM2002A to A.P. and 01EE2303B to J.P.), the Medical Faculty of Heinrich Heine University (FoKo grant to A.P. and S.C.), the European Commission’s Horizon Europe Program (SIMPATHIC #101080249 to A.P.),the National Science Centre, Poland (NCN grant No. 20 16/22/M/NZ2/00548 and 2017/27/B/NZ1/02401 to P.L.), the UK Dementia Research Institute programme grant (to J.P.), the Instituto de Salud Carlos III (ISCIII) grant PI20-00057 (to C.U.), the Berlin School of Integrative Oncology through the GSSP program of the German Academy of Exchange Service (DAAD) and the Joachim Herz Foundation through the Add-on Fellowship program (to T.M.P.), and the Studienstiftung des deutschen Volkes (to Se.Li.). We acknowledge the Center for Advanced Imaging (CAi) at Heinrich Heine University Düsseldorf for providing access to the Perki- nElmer Operetta CLS (DFG grant number INST 208/760-1 FUGG) and Olympus FV3000 microscope.Peer reviewe

Mutant huntingtin impairs neurodevelopment in human brain organoids through CHCHD2-mediated neurometabolic failure

Expansion of the glutamine tract (poly-Q) in the protein huntingtin (HTT) causes the neurodegenerative disorder Huntington’s disease (HD). Emerging evidence suggests that mutant HTT (mHTT) disrupts brain development. To gain mechanistic insights into the neurodevelopmental impact of human mHTT, we engineered male induced pluripotent stem cells to introduce a biallelic or monoallelic mutant 70Q expansion or to remove the poly-Q tract of HTT. The introduction of a 70Q mutation caused aberrant development of cerebral organoids with loss of neural progenitor organization. The early neurodevelopmental signature of mHTT highlighted the dysregulation of the protein coiled-coil-helix-coiled-coil-helix domain containing 2 (CHCHD2), a transcription factor involved in mitochondrial integrated stress response. CHCHD2 repression was associated with abnormal mitochondrial morpho-dynamics that was reverted upon overexpression of CHCHD2. Removing the poly-Q tract from HTT normalized CHCHD2 levels and corrected key mitochondrial defects. Hence, mHTT-mediated disruption of human neurodevelopment is paralleled by aberrant neurometabolic programming mediated by dysregulation of CHCHD2, which could then serve as an early interventional target for HD

Longitudinal optical binding

Longitudinal optical binding refers to the light induced self organisation of micro particles in one dimension. In this thesis I will present experimental and theoretical studies of the separation between two dielectric spheres in a counter-propagating (CP) geometry. I will explore the bistable nature of the bound sphere separation and its dependency on the refractive index mismatch between the spheres and the host medium, with an emphasis on the fibre separation. The physical under pining principle of longitudinal optical binding in the Mie regime is the refocusing effect of the light field from one sphere to its nearest neighbour. In a second set of experiments I developed means to visualise the field intensity distribution responsible for optical binding using two-photon fluorescence imaging from fluorescein added to the host medium. The experimental intensity distributions are compared to theoretical predictions and provide an in situ method to observe the binding process in real time. This coupling via the refocused light fields between the spheres is in detailed investigated experimentally and theoretically, in particular I present data and analysis on the correlated behaviour of the micro spheres in the presence of noise. The measurement of the decay times of the correlation functions of the modes of the optically bound array provides a methodology for determining the optical restoring forces acting in optical binding. Interestingly micro devices can be initiated by means of the light-matter interaction. Light induced forces and torques are exerted on such micro-objects that are then driven by the optical gradient or scattering force. I have experimentally investigate how the driving light interacts with and diffracts from the motor, utilising two-photon imaging. The micromotor rotation rate dependence on the light field parameters is explored and theoretically modelled. The results presented will show that the model can be used to optimise the system geometry and the micromotor

Theory and simulation of the bistable behaviour of optically bound particles in the Mie size regime

Optical binding refers to the light-induced organization and ordering of microparticles. In this paper, we present a theoretical treatment of optical binding in the Mie size regime using the paraxial approximation for field propagation combined with the Lorentz force law. Experimental studies of the separation between two dielectric spheres in a counter-propagating (CP) geometry are compared to numerical predictions. We explore the bistable nature of the bound sphere separation and its dependency on the refractive index mismatch between the spheres and the host medium, with an emphasis on the fibre separation and adiabaticity of the system.</p