Unraveling How Candida albicans Forms Sexual Biofilms.

Biofilms, structured and densely packed communities of microbial cells attached to surfaces, are considered to be the natural growth state for a vast majority of microorganisms. The ability to form biofilms is an important virulence factor for most pathogens, including the opportunistic human fungal pathogen Candida albicans. C. albicans is one of the most prevalent fungal species of the human microbiota that asymptomatically colonizes healthy individuals. However, C. albicans can also cause severe and life-threatening infections when host conditions permit (e.g., through alterations in the host immune system, pH, and resident microbiota). Like many other pathogens, this ability to cause infections depends, in part, on the ability to form biofilms. Once formed, C. albicans biofilms are often resistant to antifungal agents and the host immune response, and can act as reservoirs to maintain persistent infections as well as to seed new infections in a host. The majority of C. albicans clinical isolates are heterozygous (a/α) at the mating type-like (MTL) locus, which defines Candida mating types, and are capable of forming robust biofilms when cultured in vitro. These "conventional" biofilms, formed by MTL-heterozygous (a/α) cells, have been the primary focus of C. albicans biofilm research to date. Recent work in the field, however, has uncovered novel mechanisms through which biofilms are generated by C. albicans cells that are homozygous or hemizygous (a/a, a/Δ, α/α, or α/Δ) at the MTL locus. In these studies, the addition of pheromones of the opposite mating type can induce the formation of specialized "sexual" biofilms, either through the addition of synthetic peptide pheromones to the culture, or in response to co-culturing of cells of the opposite mating types. Although sexual biofilms are generally less robust than conventional biofilms, they could serve as a protective niche to support genetic exchange between mating-competent cells, and thus may represent an adaptive mechanism to increase population diversity in dynamic environments. Although conventional and sexual biofilms appear functionally distinct, both types of biofilms are structurally similar, containing yeast, pseudohyphal, and hyphal cells surrounded by an extracellular matrix. Despite their structural similarities, conventional and sexual biofilms appear to be governed by distinct transcriptional networks and signaling pathways, suggesting that they may be adapted for, and responsive to, distinct environmental conditions. Here we review sexual biofilms and compare and contrast them to conventional biofilms of C. albicans

Towards the Modeling of Neuronal Firing by Gaussian Processes

This paper focuses on the outline of some computational methods for the approximate solution of the integral equations for the neuronal firing probability density and an algorithm for the generation of sample-paths in order to construct histograms estimating the firing densities. Our results originate from the study of non-Markov stationary Gaussian neuronal models with the aim to determine the neuron's firing probability density function. A parallel algorithm has been implemented in order to simulate large numbers of sample paths of Gaussian processes characterized by damped oscillatory covariances in the presence of time dependent boundaries. The analysis based on the simulation procedure provides an alternative research tool when closed-form results or analytic evaluation of the neuronal firing densities are not available.Comment: 10 pages, 3 figures, to be published in Scientiae Mathematicae Japonica

The Cochlear Tuning Curve

The tuning curve of the cochlea measures how large an input is required to elicit a given output level as a function of the frequency. It is a fundamental object of auditory theory, for it summarizes how to infer what a sound was on the basis of the cochlear output. A simple model is presented showing that only two elements are sufficient for establishing the cochlear tuning curve: a broadly tuned traveling wave, moving unidirectionally from high to low frequencies, and a set of mechanosensors poised at the threshold of an oscillatory (Hopf) instability. These two components suffice to generate the various frequency-response regimes which are needed for a cochlear tuning curve with a high slope

a possible use of smart thermography for the control of gfrp composite laminate

Abstract The development of techniques able to check the structural health of a wind blade is very important. An innovative and promising technique applicable at this aim is the SMArt thermography. It exploits the electro-thermal properties of SMArt composites, in order to detect the structural flaws using an embedded source. Such a system enables a built-in, fast, cost-effective and in-depth assessment of the structural damage as it overcomes the limitations of standard thermography. With the aim for developing a reliable diagnostic method based on SMArt thermography, a preliminary numerical model was implemented in order to simulate the heating and the subsequent cooling of a GFRP composite laminate with embedded SMA wires. The heat source was represented by the Joule effect originated in the SMA wires and supplied as power density. The analysis of the resulting thermal maps at different values of power density provided the optimal levels of current amplitude and period to be applied in the subsequent experimental applications

Performance Comparison in the "Follicular Neoplasm" Category Between the American, British, Italian, and Japanese Systems for Reporting Thyroid Cytopathology

It is now almost ten years that the United Stated of America, England, Italy and Japan had their own reporting system to classify thyroid lesions. Important confusion and uncertainties dominated the "follicular-patterned lesions", a category also known as the "gray zone". Every cytopathologist was using a personal terminology to describe and call lesions made up of a variable admixture of macro- and microfollicular structures. These personal views varied considerably between cytopathologists and generated a great deal of confusion among patients (the cytological report being almost incomprehensible to them), clinicians and even within the same cytopathology community. With the advent of national reporting systems, things changed in a better way and standardized reporting systems became the standard of practice in thyroid cytology. The outcome of the widespread use of standardized diagnostic categories was the reduction of descriptive diagnoses and the improved communication between pathologists, clinicians and patients. In this article we review the major reporting systems, analyze their similarities and differences in the "indeterminate" or "follicular-patterned" diagnostic categories, and when possible, try to assess their performance

Single-channel analysis of a ClC-2-like chloride conductance in cultured rat cortical astrocytes

AbstractThe single-channel behavior of the hyperpolarization-activated, ClC-2-like inwardly rectifying Cl− current (IClh), induced by long-term dibutyryl-cyclic-AMP-treated cultured cortical rat astrocytes, was analyzed with the patch-clamp technique. In outside-out patches in symmetrical 144 mM Cl− solutions, openings of hyperpolarization-activated small-conductance Cl− channels revealed burst activity of two equidistant conductance levels of 3 and 6 pS. The unitary openings displayed slow activation kinetics. The probabilities of the closed and conducting states were consistent with a double-barrelled structure of the channel protein. These results suggest that the astrocytic ClC-2-like Cl− current IClh is mediated by a small-conductance Cl− channel, which has the same structural motif as the Cl− channel prototype ClC-0

Kf evaluation in GFRP composites by thermography

Since the presence of a notch in a mechanical component causes a reduction in the fatigue strength, it is important to know the kf value for a given notch geometry and material. This parameter is fundamental in the fatigue design of aeronautical components that are mainly made of composites. kf is available in the literature for numerous types of notch but only for traditional materials such as metals. This paper presents a new practice, based on thermographic data, for the determination of the fatigue notch coefficient kf in composite notched specimens. The innovative aspect of this study is therefore to propose the application on composite materials of a new thermographic procedure to determine kf for several notch geometries: circular, U and V soft and severe notches. It was calculated, for each type of notch, as the ratio between the fatigue limits obtained on the cold and hot zone corresponding to the smooth and notched specimen, respectively. Consequently, this research activity provides, for the first time, a little database of kf for two particular typologies of composite materials showing a fast way to collect further values for different laminates and notch geometries