Biomarkers of mitochondrial dysfunction and inflammaging in older adults and blood pressure variability

GeroScience - Most physiopathological mechanisms underlying blood pressure variability (BPV) are implicated in aging. Vascular aging is associated with chronic low-grade inflammation occurring in...     

Regions, systems, and the brain: hierarchical measures of functional integration in fMRI

In neuroscience, the notion has emerged that the brain abides by two principles: segregation and integration. Segregation into functionally specialized systems and integration of information flow across systems are basic principles that are thought to shape the functional architecture of the brain. A measure called integration, originating from information theory and derived from mutual information, has been proposed to characterize the global integrative state of a network. In this paper, we show that integration can be applied in a hierarchical fashion to quantify functional interactions between compound systems, each system being composed of several regions. We apply this method to fMRI datasets from patients with low-grade glioma and show how it can efficiently extract information related to both intra- and interhemispheric reorganization induced by lesional brain plasticity.     

Geometrical regularization of displacement fields for histological image registration

This article tackles the registration of 2-D biomedical images (histological sections, autoradiographs, cryosections, etc.). Our goal is to adequately match anatomical features of interest without inducing biologically improbable tissue distortions. We observe that the large variety of registration applications--3-D volume reconstruction, multimodal molecular mapping, etc.--induce a no less diverse set of requirements in terms of accuracy and robustness. In turn, these directly translate into regularization constraints on the deformation model, which should ideally be specifiable by the user. We propose an adaptive regularization approach where the rigidity constraints are informed by the registration application at hand and whose support is controlled by the geometry of the images to be registered. For each site of a sparse lattice over which a displacement field has been computed, our algorithm estimates, in a robust fashion, a rigid or affine transformation within a circular neighbourhood cut to fit the local geometry around the site. We investigate the behaviour of this technique and discuss its sensitivity to the rigidity parameter.     

Are platelets a 'forgotten' source of sepsis-induced myocardial depressing factor(s)?

The mechanism of sepsis-induced cardiac failure was initially thought to be related to the presence of 'myocardial depressant' substances that directly alter heart function. Exosomes released by platelets and identified in the plasma are suggested to, at least partially, explain myocardial depression in sepsis. This hypothesis needs to be evaluated by clinical studies.     

Region-specific differentiation of embryonic stem cell-derived neural progenitor transplants into the adult mouse hippocampus following seizures

Embryonic stem (ES) cells can generate neural progenitors and neurons in vitro and incorporate into the adult central nervous system (CNS) following transplantation, suggesting their therapeutic potential for treating neurological disorders. However, our understanding of the conditions that direct ES-derived neural progenitor (ESNP) migration and differentiation within different regions of the adult CNS is incomplete. Rodents treated with the chemoconvulsant kainic acid (KA) experience seizures and display hippocampal sclerosis, as well as enhanced hippocampal neurogenesis, similar to pathological findings in patients with temporal lobe epilepsy (TLE). To examine the potential for ESNPs to incorporate into the adult hippocampus and differentiate into hippocampal neurons or glia following seizure-induced damage, we compared the fates of ESNPs after they were transplanted into the CA3 region or fimbria 1 week following KA-induced seizures. After 4-8 weeks, ESNPs grafted into the CA3 region had migrated to the dentate gyrus (DG), where a small subset adopted neural stem cell fates and continued to proliferate, based on bromodeoxyuridine uptake. Others differentiated into neuroblasts or dentate granule neurons. In contrast, most ESNPs transplanted into the fimbria migrated extensively along existing fiber tracts and differentiated into oligodendrocytes or astrocytes. Hippocampal grafts in mice not subjected to seizures displayed a marked tendency to form tumors, and this effect was more pronounced in the DG than in the fimbria. Taken together, these data suggest that seizures induce molecular changes in the CA3 region and DG that promote region-specific neural differentiation and suppress tumor formation.     

Neocortical plasticity deficits in fetal alcohol spectrum disorders: lessons from barrel and visual cortex

Fetal Alcohol Spectrum Disorder (FASD) is characterized by a constellation of behavioral and physiological abnormalities, including learning and sensory deficits. There is growing evidence that abnormalities of neuronal plasticity underlie these deficits. However, the cellular and molecular mechanisms by which prenatal alcohol exposure disrupts neuronal plasticity remain elusive. Recently, studies with the barrel and the visual cortex as models to study the effects of early alcohol exposure on neuronal plasticity shed light on this subject. In this Mini-Review, we discuss the effects of ethanol exposure during development on neuronal plasticity and suggest environmental and pharmacological approaches to ameliorate these problems.