Correlation between Visual Acuity and Optical Coherence Tomography-Measured Retinal Thickness in Diabetic Macular Edema

Background and Objective: Diabetic macular edema (DME) is one of the common complications of diabetes which significantly accounts for preventable visual impairment and blindness. Central macular thickness (CMT) is a feature found in DME patients. This study aims to determine the relationship between optical coherence tomography (OCT)-measured CMT and visual acuity (VA) in patients with DME before and after intravitreal injection of bevacizumab. Methods: This cross-sectional study was conducted on 100 patients with diabetic macular edema with involvement of both eyes referred to the Ophthalmology Department of Rouhani Hospital in Babol who underwent intravitreal injection of Bevacizumab. VA (measured by Snellen chart), CMT (measured by OCT), clinical and paraclinical factors (including the duration of diabetes, glycosylated hemoglobin (HbA1c), fasting blood sugar (FBS), hypertension, and smoking history data) were evaluated and compared among all patients just before and 45 days after Bevacizumab injection. Findings: Before the injection of Bevacizumab in 200 eyes, the mean value of VA (letter score) and mean value of CMT (µm) were 36.83±12.73 and 425.48±85.18 µm, respectively (p<0.001, 95% CI=12.5 – 17.5 and 95% CI=-71.5 – -55.5, respectively). 45 days after Bevacizumab injection, the mean value of absolute VA changes was 15.24±10.16, and the mean value of absolute CMT changes was -67.83±43.08 µm (coefficient=-0.18, 95% CI=-0.39 – 0.05). Conclusion: Although VA was correlated moderately with CMT and the polynomial regression model enhanced the predictive ability, it remains fully obvious that CMT and clinical factors could play an essential role as VA surrogates

Anomalous density dependence of static friction in sand

We measured experimentally the static friction force $F_s$ on the surface of a glass rod immersed in dry sand. We observed that $F_s$ is extremely sensitive to the closeness of packing of grains. A linear increase of the grain-density yields to an exponentially increasing friction force. We also report on a novel periodicity of $F_s$ during gradual pulling out of the rod. Our observations demonstrate the central role of grain bridges and arches in the macroscopic properties of granular packings.Comment: plain tex, 6 pages, to appear in Phys.Rev.

Near-critical free-surface flows: Real fluid flow analysis

An open channel flow with a flow depth close to the critical depth is characterised by a curvilinear streamline flow field that results in steady free surface undulations. Near critical flows of practical relevance encompass the undular hydraulic jump when the flow changes from supercritical (F > 1) to subcritical (F 1). So far these flows were mainly studied based on ideal fluid flow computations, for which the flow is assumed irrotational and, thus, shear forces are absent. While the approach is accurate for critical flow conditions (F = 1) in weir and flumes, near-critical flows involve long distances reaches, and the effect of friction on the flow properties cannot be neglected. In the present study the characteristics of near-critical free-surface flows are reanalysed based on a model accounting for both the streamline curvature and friction effects. Based on the improved model, some better agreement with experimental results is found, thereby highlighting the main frictional features of the flow profiles

Creation of multiple nanodots by single ions

In the challenging search for tools that are able to modify surfaces on the nanometer scale, heavy ions with energies of several 10 MeV are becoming more and more attractive. In contrast to slow ions where nuclear stopping is important and the energy is dissipated into a large volume in the crystal, in the high energy regime the stopping is due to electronic excitations only. Because of the extremely local (< 1 nm) energy deposition with densities of up to 10E19 W/cm^2, nanoscaled hillocks can be created under normal incidence. Usually, each nanodot is due to the impact of a single ion and the dots are randomly distributed. We demonstrate that multiple periodically spaced dots separated by a few 10 nanometers can be created by a single ion if the sample is irradiated under grazing angles of incidence. By varying this angle the number of dots can be controlled.Comment: 12 pages, 6 figure

Tissue magnetic susceptibility mapping as a marker of tau pathology in Alzheimer's disease.

Alzheimer's disease is connected to a number of other neurodegenerative conditions, known collectively as 'tauopathies', by the presence of aggregated tau protein in the brain. Neuroinflammation and oxidative stress in AD are associated with tau pathology and both the breakdown of axonal sheaths in white matter tracts and excess iron accumulation grey matter brain regions. Despite the identification of myelin and iron concentration as major sources of contrast in quantitative susceptibility maps of the brain, the sensitivity of this technique to tau pathology has yet to be explored. In this study, we perform Quantitative Susceptibility Mapping (QSM) and T2* mapping in the rTg4510, a mouse model of tauopathy, both in vivo and ex vivo. Significant correlations were observed between histological measures of myelin content and both mean regional magnetic susceptibility and T2* values. These results suggest that magnetic susceptibility is sensitive to tissue myelin concentrations across different regions of the brain. Differences in magnetic susceptibility were detected in the corpus callosum, striatum, hippocampus and thalamus of the rTg4510 mice relative to wild type controls. The concentration of neurofibrillary tangles was found to be low to intermediate in these brain regions indicating that QSM may be a useful biomarker for early stage detection of tau pathology in neurodegenerative diseases

A VLF/LF facility network for preseismic electromagnetic investigations

Earthquakes are one of the most frequently occurring natural disasters. Many indications have been collected on the presence of seismo-ionospheric perturbations preceding such tragic phenomena. Radio techniques are the essential tools leading the detection of seismo-electromagnetic emissions by monitoring at very low-frequency (VLF, 3–30 kHz) and low-frequency (LF, 30–300 kHz) sub-ionospheric paths between transmitters and receivers (Hayakawa, 2015). In this brief communication, we present the implementation of a VLF/LF network to search for earthquake electromagnetic precursors. The proposed system is comprised of a monopole antenna including a preamplifier, a GPS receiver and a recording device. This system will deliver a steady stream of real-time amplitude and phase measurements as well as a daily recording VLF/LF data set. The first implementation of the system was done in Graz, Austria. The second one will be in Guyancourt (France), with a third one in Réunion (France) and a fourth one in Moratuwa (Sri Lanka). In the near future, we are planning to expand our network for enhanced monitoring and increased coverage.</p

p-tau Ser356 is associated with Alzheimer's disease pathology and is lowered in brain slice cultures using the NUAK inhibitor WZ4003

Tau hyperphosphorylation and aggregation is a common feature of many dementia-causing neurodegenerative diseases. Tau can be phosphorylated at up to 85 different sites, and there is increasing interest in whether tau phosphorylation at specific epitopes, by specific kinases, plays an important role in disease progression. The AMP-activated protein kinase (AMPK)-related enzyme NUAK1 has been identified as a potential mediator of tau pathology, whereby NUAK1-mediated phosphorylation of tau at Ser356 prevents the degradation of tau by the proteasome, further exacerbating tau hyperphosphorylation and accumulation. This study provides a detailed characterisation of the association of p-tau Ser356 with progression of Alzheimer's disease pathology, identifying a Braak stage-dependent increase in p-tau Ser356 protein levels and an almost ubiquitous presence in neurofibrillary tangles. We also demonstrate, using sub-diffraction-limit resolution array tomography imaging, that p-tau Ser356 co-localises with synapses in AD postmortem brain tissue, increasing evidence that this form of tau may play important roles in AD progression. To assess the potential impacts of pharmacological NUAK inhibition in an ex vivo system that retains multiple cell types and brain-relevant neuronal architecture, we treated postnatal mouse organotypic brain slice cultures from wildtype or APP/PS1 littermates with the commercially available NUAK1/2 inhibitor WZ4003. Whilst there were no genotype-specific effects, we found that WZ4003 results in a culture-phase-dependent loss of total tau and p-tau Ser356, which corresponds with a reduction in neuronal and synaptic proteins. By contrast, application of WZ4003 to live human brain slice cultures results in a specific lowering of p-tau Ser356, alongside increased neuronal tubulin protein. This work identifies differential responses of postnatal mouse organotypic brain slice cultures and adult human brain slice cultures to NUAK1 inhibition that will be important to consider in future work developing tau-targeting therapeutics for human disease.</p