Search results for "mixtures"

Preliminary Studies on Microbial Biomass and the Microarthropod Community as Soil Health and Quality Indicators in Urban Grasslands, Rīga as an Examp…

2015

Antropogēnais piesārņojums tiek uzskatīts par vienu no galvenajiem faktoriem, kas ietekmē augsni pilsētās. 2014. gadā uzsākts pētījums par augsnes kvalitāti urbānajos zālājos Rīgā. Pētījuma mērķis bija noteikt augsnes mikrobiālo biomasu un augsnes sīkposmkāju kopienu dažādu zālāju augsnēs Rīgā un izvērtēt iespējas tos izmantot kā pilsētvides augsnes veselības un kvalitātes rādītājus. Rīgā atšķirīgos pilsētas rajonos tika izvēlēti seši dažāda lieluma parauglaukumi ar atšķirīgām vietas apbūves īpatnībām, ielu un dzelzceļu tīkla blīvumu un transporta noslogojumu, vidi piesārņojošo objektu iespējamo ietekmi, kā arī citām, urbānu vidi raksturojošām īpatnībām. Substrāta izraisītas elpošanas metod…

LisRK is required for optimal fitness ofListeria monocytogenesin soil

2020

ABSTRACTListeria monocytogenes is a food-borne pathogen responsible for the disease listeriosis. It is ubiquitously found in the environment and soil is one of its natural habitats. Listeria monocytogenes is highly capable of coping with various stressful conditions. We hypothesized that stress-responsive two-component systems such as LisRK might contribute to the adaptation of L. monocytogenes to the soil environment. Indeed, investigations of the population dynamics of wild-type and mutant strains suggest an important role of LisRK for optimal fitness of L. monocytogenes in sterile soil. Results from non-sterile soil showed that the parental strain was capable of surviving longer than mut…

Sensitivity of neuronal nicotinic acetylcholine receptors to the opiate antagonists naltrexone and naloxone: receptor blockade and up-regulation

2003

In HEK293 cells stably expressing alpha4beta2 nAChRs, naltrexone, but not naloxone, blocked alpha4beta2 nAChRs via an open-channel blocking mechanism. In primary hippocampal cultures, naltrexone inhibited alpha7 nAChRs up-regulated by nicotine, and in organotypic hippocampal cultures naltrexone caused a time-dependent up-regulation of functional alpha7 nAChRs that was detected after removal of the drug. These results indicate that naltrexone could be used as a smoking cessation aid.

Site selection for the new generation of giant neutrino detectors

2012

The main findings of the LAGUNA Design Study are briefly discussed. Construction of giant underground detectors is technically feasible at several sites. Physics factors will dominate in the site selection.

PIH32 What are the Factors Influencing Parental Apprehension About Consenting Children to Participate in Pediatric Observational Studies? A Survey Co…

2011

Evolution of available lysine and furosine contents in milk-based infant formulas throughout the shelf-life storage period

2003

The evolution of the Maillard reaction (MR) by measuring the available lysine and furosine (FUR) contents in adapted and follow-up powdered milk-based infant formulas over the shelf-life storage period, at 20 and 37 °C, was studied. Available lysine and FUR contents were determined by fluorimetry and high-performance liquid chromatography respectively. Statistically significant differences were found between adapted and follow-up infant formulas with respect to the available lysine and FUR contents. Available lysine contents decreased significantly throughout the storage time, and the contents at 37 °C were lower than at 20 °C. A statistically significant increase in FUR contents was observ…

Les récepteurs olfactifs et le codage des odeurs

2008

The first step of the olfactory detection involves the activation by odorants of olfactory receptors, which are membrane proteins embedded in the membrane of olfactory neurons. Odour coding results from the combinatory activation of a set of receptors and rests on their clonal expression. Neuronal olfactory connexion leads to the formation, in the cortex, of a specific sensory map, which gives rise to the odor perception. This combinatorial system allows, with approximately 340 different receptors, to discriminate myriads of odorants that are natural or not (new cooking flavours, synthetic chemicals…). The extreme olfactory genome diversity in human beings may explain different food behavio…

Cytotoxicity, Genotoxicity and Disturbance of Cell Cycle in HepG2 Cells Exposed to OTA and BEA: Single and Combined Actions

2019

Mycotoxins are produced by a number of fungal genera spp., for example, Aspergillus, Penicillium, Alternaria, Fusarium, and Claviceps. Beauvericin (BEA) and Ochratoxin A (OTA) are present in various cereal crops and processed grains. This goal of this study was to determine their combination effect in HepG2 cells, presented for the first time. In this study, the type of interaction among BEA and OTA through an isobologram method, cell cycle disturbance by flow cytometry, and genotoxic potential by in vitro micronucleus (MN) assay following the TG 487 (OECD, 2016) of BEA and OTA individually and combined in HepG2 cells are presented. Cytotoxic concentration ranges studied by the MTT assay ov…

Just noticeable differences in component concentrations modify the odor quality of a blending mixture.

2008

International audience; The odors we perceive are mainly the result of mixtures of odorants that, however, are commonly perceived as single undivided entities; nevertheless, the processes involved remain poorly explored. It has been recently reported that perceptual blending based on configural olfactory processing can cause odorant mixtures to give rise to an emergent odor not present in the components. The present study examined whether specific component proportions are required to elicit an emergent odor. Starting from the composition of a ternary target mixture in which an emergent pineapple odor was perceived, 4 concentration levels of each component were chosen to elicit just noticea…

Neonatal representation of odour objects: distinct memories of the whole and its parts

2014

Extraction of relevant information from highly complex environments is a prerequisite to survival. Within odour mixtures, such information is contained in the odours of specific elements or in the mixture configuration perceived as a whole unique odour. For instance, an AB mixture of the element A (ethyl isobutyrate) and the element B (ethyl maltol) generates a configural AB percept in humans and apparently in another species, the rabbit. Here, we examined whether the memory of such a configuration is distinct from the memory of the individual odorants. Taking advantage of the newborn rabbit's ability to learn odour mixtures, we combined behavioural and pharmacological tools to specifically…