Impaired recovery in diabetic rat nerve following anoxic conduction block

It is well documented that diabetic rats and subjects have a paradoxical resistance to ischemic conduction block although the nerves of diabetics are more susceptible to entrapment neuropathies. The aim of the present study was to further analyze the effect of anoxia on the diabetic nerve. Nerve conduction was measured in vitro in desheathed sciatic nerves from spontaneously diabetic rats (BB-Wistar) and age-matched controls. After onset of anoxia the compound action potential (CAP) decreased to 50% in 17 min in diabetic rat nerves and 8 min in normals. Following reoxygenation CAP recovered to 50% in 30 s in normal rat nerves and after 3 min the recovery was 92%. In nerves from diabetic animals 50% recovery took 4 min, but still after 12 min CAP was suppressed to a 60% level of the original. Longer periods of anoxia did not impair the recovery in normal nerve as it did in the diabetic ones. This defective recovery after anoxia in nerves from diabetic animals may be relevant for the understanding of the pathogenesis of entrapment neuropathies in diabetic subjects.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31284/1/0000190.pd

Robustly estimating the flow direction of information in complex physical systems

We propose a new measure to estimate the direction of information flux in multivariate time series from complex systems. This measure, based on the slope of the phase spectrum (Phase Slope Index) has invariance properties that are important for applications in real physical or biological systems: (a) it is strictly insensitive to mixtures of arbitrary independent sources, (b) it gives meaningful results even if the phase spectrum is not linear, and (c) it properly weights contributions from different frequencies. Simulations of a class of coupled multivariate random data show that for truly unidirectional information flow without additional noise contamination our measure detects the correct direction as good as the standard Granger causality. For random mixtures of independent sources Granger Causality erroneously yields highly significant results whereas our measure correctly becomes non-significant. An application of our novel method to EEG data (88 subjects in eyes-closed condition) reveals a strikingly clear front-to-back information flow in the vast majority of subjects and thus contributes to a better understanding of information processing in the brain.Comment: 5 pages, 4 figure

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

A mechanistic model of mismatch negativity in the ageing brain

Objective: We investigated the neurophysiological mechanisms underpinning the generation of the mismatch negativity (MMN) in the ageing brain. Methods: We used dynamic causal modelling (DCM) to study connectivity models for healthy young and old subjects. MMN was elicited with an auditory odd-ball paradigm in two groups of healthy subjects with mean age 74 (n= 30) and 26 (n= 26). DCM was implemented using up to five cortical nodes. We tested models with different hierarchical complexities. Results: We showed that the network generating MMN consisted of 5 nodes that could modulate all intra- and inter-nodal connections. The inversion of this model showed that old subjects had increased input from rSTG to the rIFG (

Cognitive impairment has a strong relation to nonsomatic symptoms of depression in relapsing-remitting multiple sclerosis

It is unclear how cognitive impairment in multiple sclerosis (MS) is influenced by physical disability, fatigue, and depression. Our aim was to identify the strongest clinical predictors for cognitive impairment in relapsing-remitting MS (RRMS) patients. The clinical risk factors included in the analysis were physical disability (EDSS), fatigue (FSS), the somatic and nonsomatic components of depression (BDI), disease progression rate [Multiple Sclerosis Severity Score (MSSS)], and psychotropic medication. Cognitive impairment had a prevalence of 30.5% in patients affecting preferentially attention, executive functions, processing speed and visual perception/organization. MSSS was not associated with cognitive impairment, depression, or fatigue. In regression models, cognitive performance was best predicted by the nonsomatic symptoms of depression alone or in combination with physical disability. Exclusion of patients with any psychotropic medication did not influence the results. Our results underscore the importance of evaluating depressive symptoms when suspecting cognitive impairment in patients with RRMS