Search results for "physiologic"

Investigation of the roles of AgrA and σB regulators in Listeria monocytogenes adaptation to roots and soil

2020

ABSTRACT Little is known about the regulatory mechanisms that ensure the survival of the food-borne bacterial pathogen Listeria monocytogenes in the telluric environment and on roots. Earlier studies have suggested a regulatory overlap between the Agr cell–cell communication system and the general stress response regulator σB. Here, we investigated the contribution of these two systems to root colonisation and survival in sterilised and biotic soil. The ability to colonise the roots of the grass Festuca arundinacea was significantly compromised in the double mutant (∆agrA∆sigB). In sterile soil at 25°C, a significant defect was observed in the double mutant, suggesting some synergy between …

Diminishing Returns of Population Size in the Rate of RNA Virus Adaptation

2000

ABSTRACT Whenever an asexual viral population evolves by adapting to new environmental conditions, beneficial mutations, the ultimate cause of adaptation, are randomly produced and then fixed in the population. The larger the population size and the higher the mutation rate, the more beneficial mutations can be produced per unit time. With the usually high mutation rate of RNA viruses and in a large enough population, several beneficial mutations could arise at the same time but in different genetic backgrounds, and if the virus is asexual, they will never be brought together through recombination. Thus, the best of these genotypes must outcompete each other on their way to fixation. This c…

Invagination of the Sphenoid Sinus Mucosa after Endoscopic Endonasal Transsphenoidal Approach and Its Significance

2016

Objective To describe the clinical features of invagination of the sphenoid sinus mucosa (ISM) and compare them with other similar cases using a visual analog scale (VAS) to assess the various nasal symptoms and to discuss its clinical significance and means of prevention. Study design Retrospective chart review at a tertiary referral center. Methods Between 2010 and 2015, 8 patients who had undergone EETSA surgery displayed postoperative ISM. The comparison group consisted of 147 patients who underwent the same surgical procedures and were diagnosed with the same diseases. Pre- or postoperative paranasal sinus computed tomography (PNS CT) and VAS were performed and subsequently analyzed. R…

T-2 toxin and its metabolites: Characterization, cytotoxic mechanisms and adaptive cellular response in human hepatocarcinoma (HepG2) cells

2020

Abstract The T-2 toxin (T-2) is a type A trichothecene produced by Fusarium species, and the most cytotoxic mycotoxin of the group. A study was made to determine T-2 cytotoxicity in human hepatocarcinoma (HepG2) cells; evaluate whether there is an adaptive response of HepG2 cells exposed to low concentrations of T-2; identify the T-2 metabolites by LC-Q-TOF MS; and determine whether T-2 disrupts cell proliferation in HepG2 cells. The IC50 values obtained ranged from 61.9 ± 2.4 nM to 70.7 ± 7.4 nM. No adaptive response was observed. There was no evidence of extra- or intracellular accumulation of T-2 after 24 h of exposure as determined by LC-Q-TOF MS. However, some T-2 metabolites such as H…

Role of Phospholipase D Activation in Nervous System Physiology and Pathophysiology

2002

tRNA-derived fragments: A new class of non-coding RNA with key roles in nervous system function and dysfunction

2021

tRNA-derived small RNAs (tsRNA) are a recently identified family of non-coding RNA that have been associated with a variety of cellular functions including the regulation of protein translation and gene expression. Recent sequencing and bioinformatic studies have identified the broad spectrum of tsRNA in the nervous system and demonstrated that this new class of non-coding RNA is produced from tRNA by specific cleavage events catalysed by ribonucleases such as angiogenin and dicer. Evidence is also accumulating that production of tsRNA is increased during disease processes where they regulate stress responses, proteostasis, and neuronal survival. Mutations to tRNA cleaving and modifying enz…

FRN and P3 during the Iowa gambling task: The importance of gender.

2020

Previous research has shown gender-related psychobiological differences in risky and competitive strategies that affect win and loss outcomes. In addition, some studies have found differences in the decision-making process, with women taking longer to reach the same performance as men. However, the underlying neural mechanisms remain unclear. The present study aimed to investigate gender differences in behavioral performance and neural correlates during a decision-making task, the Iowa Gambling Task (IGT). Forty healthy young adults (23 men and 17 women) performed the IGT while the feedback-related negativity (FRN) and P3 were recorded as neural correlates of feedback processing. No gender …

Supramodal neural processing of abstract information conveyed by speech and gesture

2013

Abstractness and modality of interpersonal communication have a considerable impact on comprehension. They are relevant for determining thoughts and constituting internal models of the environment. Whereas concrete object-related information can be represented in mind irrespective of language, abstract concepts require a representation in speech. Consequently, modality-independent processing of abstract information can be expected. Here we investigated the neural correlates of abstractness (abstract vs. concrete) and modality (speech vs. gestures), to identify an abstractness-specific supramodal neural network. During fMRI data acquisition 20 participants were presented with videos of an ac…

Making a mountain out of a molehill: on the role of the rostral dorsal anterior cingulate and dorsomedial prefrontal cortex in conscious threat appra…

2013

According to appraisal theories fear and anxiety are elicited by the subjective evaluation of a situation or internal state as threatening. From this perspective anxiety disorders result from maladaptive, exaggerated threat appraisals that over-estimate the threatening consequences of often innocuous stimuli and situations. When these threat over-estimations occur at the level of conscious processing, they are referred to as catastrophizing and worrying. Both are major pathogenic processes in many clinical theories of anxiety. Until recently, little has been known about the neurobiological basis of normal and pathological conscious threat appraisal. Here, we review functional neuroimaging s…

Paracrine regulation of neural stem cells in the subependymal zone.

2012

Stem cells maintain their self-renewal and multipotency capacities through a self-organizing network of transcription factors and intracellular pathways activated by extracellular signaling from the microenvironment or "niche" in which they reside in vivo. In the adult mammalian brain new neurons continue to be generated throughout life of the organisms and this lifelong process of neurogenesis is supported by a reservoir of neural stem cells in the germinal regions. The discovery of adult neurogenesis in the mammalian brain has sparked great interest in defining the conditions that guide neural stem cell (NSC) maintenance and differentiation into the great variety of neuronal and glial sub…