Some reasons to build a new laser Doppler flowmeter to monitor microvascular blood flow

Disturbance in the blood microcirculation is a frequent complication in a number of common diseases including diabetes, arteriosclerosis and Raynaud’s phenomenon. In order to effectively diagnose these diseases, clinical tools able to monitor non-invasively the microvascular perfusion are required. For that purpose several techniques have been proposed. Among them, laser Doppler flowmetry (LDF) has been developed over the years, from experimental tools into commercial products, and several thousands of publications cite its use in the scientific literature. Nowadays, the LDF technique is commonly proposed in diverse applications. However, the dependence of the LDF signal on the microvascular architecture is still not known. A scientific understanding and knowledge of the LDF signal origin is not yet accessible to clinicians. Some studies proposed the use of different fiber separations or several wavelengths in order to modify the sampling depth of the LDF technique. However, further work is required to have knowledge and control over the mean sampling depth (and hence volume) in skin tissue

Forebrain Deletion of αGDI in Adult Mice Worsens the Pre-Synaptic Deficit at Cortico-Lateral Amygdala Synaptic Connections

The GDI1 gene encodes αGDI, which retrieves inactive GDP-bound RAB from membranes to form a cytosolic pool awaiting vesicular release. Mutations in GDI1 are responsible for X-linked Intellectual Disability. Characterization of the Gdi1-null mice has revealed alterations in the total number and distribution of hippocampal and cortical synaptic vesicles, hippocampal short-term synaptic plasticity and specific short-term memory deficits in adult mice, which are possibly caused by alterations of different synaptic vesicle recycling pathways controlled by several RAB GTPases. However, interpretation of these studies is complicated by the complete ablation of Gdi1 in all cells in the brain throughout development. In this study, we generated conditionally gene-targeted mice in which the knockout of Gdi1 is restricted to the forebrain, hippocampus, cortex and amygdala and occurs only during postnatal development. Adult mutant mice reproduce the short-term memory deficit previously reported in Gdi1-null mice. Surprisingly, the delayed ablation of Gdi1 worsens the pre-synaptic phenotype at cortico-amygdala synaptic connections compared to Gdi1-null mice. These results suggest a pivotal role of αGDI via specific RAB GTPases acting specifically in forebrain regions at the pre-synaptic sites involved in memory formation

Application of multifractal wavelet analysis to spontaneous fermentation processes

An algorithm is presented here to get more detailed information, of mixed culture type, based exclusively on the biomass concentration data for fermentation processes. The analysis is performed with only the on-line measurements of the redox potential being available. It is a two-step procedure which includes an Artificial Neural Network (ANN) that relates the redox potential to the biomass concentrations in the first step. Next, a multifractal wavelet analysis is performed using the biomass estimates of the process. In this context, our results show that the redox potential is a valuable indicator of microorganism metabolic activity during the spontaneous fermentation. In this paper, the detailed design of the multifractal wavelet analysis is presented, as well as its direct experimental application at the laboratory levelComment: 12 pages, 3 figures, Physica A, to appea

Development of a Low Bias Method for Characterizing Viral Populations Using Next Generation Sequencing Technology

Background: With an estimated 38 million people worldwide currently infected with human immunodeficiency virus (HIV), and an additional 4.1 million people becoming infected each year, it is important to understand how this virus mutates and develops resistance in order to design successful therapies. Methodology/Principal Findings: We report a novel experimental method for amplifying full-length HIV genomes without the use of sequence-specific primers for high throughput DNA sequencing, followed by assembly of full length viral genome sequences from the resulting large dataset. Illumina was chosen for sequencing due to its ability to provide greater coverage of the HIV genome compared to prior methods, allowing for more comprehensive characterization of the heterogeneity present in the HIV samples analyzed. Our novel amplification method in combination with Illumina sequencing was used to analyze two HIV populations: a homogenous HIV population based on the canonical NL4-3 strain and a heterogeneous viral population obtained from a HIV patient's infected T cells. In addition, the resulting sequence was analyzed using a new computational approach to obtain a consensus sequence and several metrics of diversity. Significance: This study demonstrates how a lower bias amplification method in combination with next generation DNA sequencing provides in-depth, complete coverage of the HIV genome, enabling a stronger characterization of the quasispecies present in a clinically relevant HIV population as well as future study of how HIV mutates in response to a selective pressure

Multichannel time-frequency complexity measures for the analysis of age-related changes in neuromagnetic resting-state activity

We propose new multichannel time-frequency complexity measures to evaluate differences on magnetoencephalograpy (MEG) recordings between healthy young and old subjects at rest at different spatial scales. After reviewing the Renyi and singular value decomposition entropies based on time-frequency representations, we introduce multichannel generalizations, using multilinear singular value decomposition for one of them. We test these quantities on synthetic data, illustrating how the introduced complexity measures focus on number of components, nonstationarity and similarity across channels. Friedman tests are used to confirm the differences between young and old groups, and heterogeneity within groups. Experimental results show a consistent increase in complexity measures for the old group. When analyzing the topographical distribution of complexity values, we found clusters in the frontal sensors. The complexity measures here introduced seem to be a better indicator of the neurophysiologic changes of aging than power envelope connectivity. Here we applied new multichannel time-frequency complexity measures to resting-state MEG recordings from healthy young and old subjects. We showed that these features are able to reveal regional clusters. The multichannel time-frequency complexities can be used to monitor the aging of subjects. They also allow a mutual information approach, and could be applied to a wider range of problems

Survival of the Fittest: Positive Selection of CD4+ T Cells Expressing a Membrane-Bound Fusion Inhibitor Following HIV-1 Infection

Although a variety of genetic strategies have been developed to inhibit HIV replication, few direct comparisons of the efficacy of these inhibitors have been carried out. Moreover, most studies have not examined whether genetic inhibitors are able to induce a survival advantage that results in an expansion of genetically-modified cells following HIV infection. We evaluated the efficacy of three leading genetic strategies to inhibit HIV replication: 1) an HIV-1 tat/rev-specific small hairpin (sh) RNA; 2) an RNA antisense gene specific for the HIV-1 envelope; and 3) a viral entry inhibitor, maC46. In stably transduced cell lines selected such that >95% of cells expressed the genetic inhibitor, the RNA antisense envelope and viral entry inhibitor maC46 provided the strongest inhibition of HIV-1 replication. However, when mixed populations of transduced and untransduced cells were challenged with HIV-1, the maC46 fusion inhibitor resulted in highly efficient positive selection of transduced cells, an effect that was evident even in mixed populations containing as few as 1% maC46-expressing cells. The selective advantage of the maC46 fusion inhibitor was also observed in HIV-1-infected cultures of primary T lymphocytes as well as in HIV-1-infected humanized mice. These results demonstrate robust inhibition of HIV replication with the fusion inhibitor maC46 and the antisense Env inhibitor, and importantly, a survival advantage of cells expressing the maC46 fusion inhibitor both in vitro and in vivo. Evaluation of the ability of genetic inhibitors of HIV-1 replication to confer a survival advantage on genetically-modified cells provides unique information not provided by standard techniques that may be important in the in vivo efficacy of these genes

Astroglial d-serine is the endogenous co-agonist at the presynaptic NMDA receptor in rat entorhinal cortex

Presynaptic NMDA receptors facilitate the release of glutamate at excitatory cortical synapses and are involved in regulation of synaptic dynamics and plasticity. At synapses in the entorhinal cortex these receptors are tonically activated and provide a positive feedback modulation of the level of background excitation. NMDA receptor activation requires obligatory occupation of a co-agonist binding site, and in the present investigation we have examined whether this site on the presynaptic receptor is activated by endogenous glycine or d-serine. We used whole-cell patch clamp recordings of spontaneous AMPA receptor-mediated synaptic currents from rat entorhinal cortex neurones in vitro as a monitor of presynaptic glutamate release. Addition of exogenous glycine or d-serine had minimal effects on spontaneous release, suggesting that the co-agonist site was endogenously activated and likely to be saturated in our slices. This was supported by the observation that a co-agonist site antagonist reduced the frequency of spontaneous currents. Depletion of endogenous glycine by enzymatic breakdown with a bacterial glycine oxidase had little effect on glutamate release, whereas d-serine depletion with a yeast d-amino acid oxidase significantly reduced glutamate release, suggesting that d-serine is the endogenous agonist. Finally, the effects of d-serine depletion were mimicked by compromising astroglial cell function, and this was rescued by exogenous d-serine, indicating that astroglial cells are the provider of the d-serine that tonically activates the presynaptic NMDA receptor. We discuss the significance of these observations for the aetiology of epilepsy and possible targeting of the presynaptic NMDA receptor in anticonvulsant therapy. © 2014 Elsevier Ltd. All rights reserved