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Strong Involvement (strong + involvement)

Distribution by Scientific Domains
Life Sciences50%

Selected Abstracts

Model of cryptogenic infantile spasms after prenatal corticosteroid priming

EPILEPSIA, Issue 2010
Libor Velí
Summary Infantile spasms (IS) is a devastating epilepsy syndrome of childhood. IS occurs in 3,12-month-old infants and is characterized by spasms, interictal electroencephalography (EEG) hypsarrhythmia, and profound mental retardation. Hormonal therapy [adrenocorticotropic hormone (ACTH), corticosteroids] is frequently used, but its efficacy is tainted by severe side effects. For research of novel therapies, a validated animal model of IS is required. We propose the model of spastic seizures triggered by N -methyl- d -aspartate (NMDA) in infant rats prenatally exposed to betamethasone. The spasms have remarkable similarity to human IS, including motor flexion spasms, ictal EEG electrodecrement, and responsiveness to ACTH. Interestingly, the spasms do not involve the hippocampus. Autoradiographic metabolic mapping as well as tagging of the areas of neuronal excitation with c-fos indicates a strong involvement of hypothalamic structures such as the arcuate nucleus, which has significant bilateral connections with other hypothalamic nuclei as well as with the brainstem. [source]

Differential patterns of cortical activation as a function of fluid reasoning complexity

HUMAN BRAIN MAPPING, Issue 2 2009
Bernardo Perfetti
Abstract Fluid intelligence (gf) refers to abstract reasoning and problem solving abilities. It is considered a human higher cognitive factor central to general intelligence (g). The regions of the cortex supporting gf have been revealed by recent bioimaging studies and valuable hypothesis on the neural correlates of individual differences have been proposed. However, little is known about the interaction between individual variability in gf and variation in cortical activity following task complexity increase. To further investigate this, two samples of participants (high-IQ, N = 8; low-IQ, N = 10) with significant differences in gf underwent two reasoning (moderate and complex) tasks and a control task adapted from the Raven progressive matrices. Functional magnetic resonance was used and the recorded signal analyzed between and within the groups. The present study revealed two opposite patterns of neural activity variation which were probably a reflection of the overall differences in cognitive resource modulation: when complexity increased, high-IQ subjects showed a signal enhancement in some frontal and parietal regions, whereas low-IQ subjects revealed a decreased activity in the same areas. Moreover, a direct comparison between the groups' activation patterns revealed a greater neural activity in the low-IQ sample when conducting moderate task, with a strong involvement of medial and lateral frontal regions thus suggesting that the recruitment of executive functioning might be different between the groups. This study provides evidence for neural differences in facing reasoning complexity among subjects with different gf level that are mediated by specific patterns of activation of the underlying fronto-parietal network. Hum Brain Mapp, 2009. © 2007 Wiley-Liss, Inc. [source]

A Comparison Between One-Tier and Two-Tier Board Structures in France

JOURNAL OF INTERNATIONAL FINANCIAL MANAGEMENT & ACCOUNTING, Issue 3 2010
Benedicte Millet-Reyes
French companies operate in a unique environment characterized by the strong involvement of block shareholders such as families and banks. Furthermore, the French legal system allows firms to choose between a one-tier or a two-tier board structure. This study investigates whether this choice can affect the firm's operating and stock performance. Our regression results provide strong evidence that ownership and board structures are used together as corporate governance tools. In particular, the agency cost of debt is strongly affected by their interaction when institutional investors are also bank lenders. Our test results show that while family control has a negative impact on corporate governance, French institutional blockholders play a positive role as monitors of one-tier structures. In contrast, they are more likely to misuse the two-tier board system by promoting interlocked directorship, board opacity and their own interests as creditors. Our regression analysis reveals that foreign institutional investors do not have any impact on firm performance, regardless of board structure. Finally, we do not find any inverse relationship between board size and efficiency in France. [source]

Impairment of blood,cerebrospinal fluid barrier properties by retrovirus-activated T lymphocytes: reduction in cerebrospinal fluid-to-blood efflux of prostaglandin E2

JOURNAL OF NEUROCHEMISTRY, Issue 6 2005
Seng Thuon Khuth
Abstract The choroid plexus epithelium forms the interface between the blood and the CSF. In conjunction with the tight junctions restricting the paracellular pathway, polarized specific transport systems in the choroidal epithelium allow a fine regulation of CSF-borne biologically active mediators. The highly vascularized stroma delimited by the choroidal epithelium can be a reservoir for retrovirus-infected or activated immune cells. In this work, new insight in the implication of the blood,CSF barrier in neuroinfectious and inflammatory diseases is provided by using a differentiated cellular model of the choroidal epithelium, exposed to infected T lymphocytes. We demonstrate that T cells activated by a retroviral infection, but not non-infected cells, reduce the transporter-mediated CSF-to-blood efflux of organic anions, in particular that of the potent pro-inflammatory prostaglandin PGE2, via the release of soluble factors. A moderate alteration of the paracellular permeability also occurs. We identified the viral protein Tax, oxygenated free radicals, matrix-metalloproteinases and pro-inflammatory cytokines as active molecules released during the exposure of the epithelium to infected T cells. Among them, tumour necrosis factor and interleukin 1 are directly involved in the mechanism underlying the decrease in some choroidal organic anion efflux. Given the strong involvement of CSF-borne PGE2 in sickness behaviour syndrome, these data suggest that the blood,CSF barrier plays an important role in the pathophysiology of neuroinflammation and neuroinfection, via changes in the transport processes controlling the CSF biodisposition of PGE2. [source]