Tonic Shock Induces Detachment of Giardia lamblia

The single-celled organism Giardia lamblia colonizes the small intestine of a wide variety of hosts, including humans. Giardiasis infections can cause severe gastrointestinal symptoms and pose a major health concern in the developing world. Giardia are known to attach robustly to a variety of surfaces, but the conditions that influence this attachment are not known. In this study, we examined the behavior of attached Giardia parasites exposed to rapid changes in solution properties, like those Giardia might encounter in the intestine. After systematically varying media concentration and composition, we found that only one solution property caused rapid detachment of Giardia cells: tonicity, which is a measure of the total concentration of solutes in the solution that are unable to pass through a semi-permeable membrane (here, the cell membrane of Giardia). We found similar results for Giardia initially attached to monolayers of intestinal cells. Giardia cells remaining attached after a change in tonicity are able to adapt to the change, highlighting the general ability of this organism to weather normal changes in the intestinal environment. We propose that Giardia's susceptibility to large changes in tonicity could be explored as a possible new route for treatment of giardiasis

Warm Body Temperature Facilitates Energy Efficient Cortical Action Potentials

The energy efficiency of neural signal transmission is important not only as a limiting factor in brain architecture, but it also influences the interpretation of functional brain imaging signals. Action potential generation in mammalian, versus invertebrate, axons is remarkably energy efficient. Here we demonstrate that this increase in energy efficiency is due largely to a warmer body temperature. Increases in temperature result in an exponential increase in energy efficiency for single action potentials by increasing the rate of Na+ channel inactivation, resulting in a marked reduction in overlap of the inward Na+, and outward K+, currents and a shortening of action potential duration. This increase in single spike efficiency is, however, counterbalanced by a temperature-dependent decrease in the amplitude and duration of the spike afterhyperpolarization, resulting in a nonlinear increase in the spike firing rate, particularly at temperatures above approximately 35°C. Interestingly, the total energy cost, as measured by the multiplication of total Na+ entry per spike and average firing rate in response to a constant input, reaches a global minimum between 37–42°C. Our results indicate that increases in temperature result in an unexpected increase in energy efficiency, especially near normal body temperature, thus allowing the brain to utilize an energy efficient neural code

Food-dependent, exercise-induced gastrointestinal distress

Among athletes strenuous exercise, dehydration and gastric emptying (GE) delay are the main causes of gastrointestinal (GI) complaints, whereas gut ischemia is the main cause of their nausea, vomiting, abdominal pain and (blood) diarrhea. Additionally any factor that limits sweat evaporation, such as a hot and humid environment and/or body dehydration, has profound effects on muscle glycogen depletion and risk for heat illness. A serious underperfusion of the gut often leads to mucosal damage and enhanced permeability so as to hide blood loss, microbiota invasion (or endotoxemia) and food-born allergen absorption (with anaphylaxis). The goal of exercise rehydration is to intake more fluid orally than what is being lost in sweat. Sports drinks provide the addition of sodium and carbohydrates to assist with intestinal absorption of water and muscle-glycogen replenishment, respectively. However GE is proportionally slowed by carbohydrate-rich (hyperosmolar) solutions. On the other hand, in order to prevent hyponatremia, avoiding overhydration is recommended. Caregiver's responsibility would be to inform athletes about potential dangers of drinking too much water and also advise them to refrain from using hypertonic fluid replacements

Type-2 Fuzzy Decision Making by means of a BL-algebra

In this paper a new method that formalizes fuzzy-based Decision Making problems by means of type-2 fuzzy sets is illustrated. The approach is based on a BL-algebra defined on these sets. This method is then compared to well-known fuzzy-based methods, namely Bellman-Zadeh's, Yager's and Baldwin's. The results achieved by our algorithm are similar and the linguistic presentation offers the advantage of making them more readable

Algebraic models and mv-algebras for fuzzy reasoning

This special issue moves from the last trends of mathematical research in fuzzy logic from its unlimited ground of applications, especially in the field of many-valued reasoning. It is well known that fuzzy logic is the logic of the "vague" concepts; its enormous success stands principally in the applicational aspects, minor progress must be noted in its mathematical fundaments. Since 1986 the MV-Algebras of the sentential calculus of Lukasiewicz seems to be a powerful tool to develop a serious well-founded algebraic calculus of fuzzy set theory, just like Boolean algebras do for classical set theory. The collection of papers here presented covers a wide spectrum of applications of these algebras to the fuzzy set theory and conversely, that is usual topics dealt in fuzzy environment are read from an "MV-point of view". This is possible because the usual fuzzy algebra [0,1] x of the fuzzy set from a referential set X into [0,1] is seen as an MV-algebra. Then popular fuzzy arguments like triangular norms, fuzzy probability, fuzzy inference, etc. find a better logical collocation in this new context and of course are redefined and rediscussed. The papers of S. Ray and S. Sessa, C.S. Hoo, V. Novak, G. Georgescu and I. Leustean, M. Chakraborty and J. Sen, C.A. Drossos and P. Karazeris go along these streams of investigation. We remind the interested fuzzists to the mentioned authors for a deeper and careful reading. The remaining papers of H.T. Nguyen et al., R.S. So16 et al., L. Di Lascio et al. cover other and different interesting arguments useful in approximate reasoning. Strictly speaking, these authors, respectively, show "how" to approximate a continuous t-norm by a strict Archimedean tnorm, "how" to build possibilistic networks for the management of imprecision coming from data and "how" to fuzzify the user's behavior during the navigation in a hypermedia system. Here "how" can be understood as the synonym of "algebraic model" (to a certain extent). Thanks are due to Piero Bonissone for his availability to consent the publication of this special issue