Polysomnographic Characteristics of Sleep in Stroke: A Systematic Review and Meta-Analysis

BackgroundResearch on sleep after stroke has focused mainly on sleep disordered breathing. However, the extend to which sleep physiology is altered in stroke survivors, how these alterations compare to healthy volunteers, and how sleep changes might affect recovery as well as physical and mental health has yet to be fully researched. Motivated by the view that a deeper understanding of sleep in stroke is needed to account for its role in health and well-being as well as its relevance for recovery and rehabilitation, we conducted a systematic review and meta-analysis of polysomnographic studies comparing stroke to control populations.MethodMedline and PsycInfo databases were searched using "stroke" and words capturing polysomnographic parameters as search terms. This yielded 1692 abstracts for screening, with 15 meeting the criteria for systematic review and 9 for meta-analysis. Prisma best practice guidelines were followed for the systematic review; the Comprehensive Meta-Analysis software was used for random effects modelling.ResultsThe meta-analysis revealed that patients with stroke have poorer sleep than controls. Patients had lower sleep efficiency (mean 75% vs 84%), shorter total-sleep-time (309.4 vs 340.3 min) and more wake-after-sleep-onset (97.2 vs 53.8 min). Patients also spend more time in stage 1 (13% vs 10%) and less time in stage 2 sleep (36% vs 45%) and slow-wave-sleep (10% vs 12%). No group differences were identified for REM sleep. The systematic review revealed a strong bias towards studies in the early recovery phase of stroke, with no study reporting specifically on patients in the chronic state. Moreover, participants in the control groups included community samples as well as other patients groups.ConclusionsThese results indicate poorer sleep in patients with stroke than controls. While strongly suggestive in nature, the evidence base is limited and methodologically diverse, and hands a clear mandate for further research. A particular need regards polysomnographic studies in chronic community-dwelling patients compared to age-matched individuals.     

The role of medial temporal lobe structures in implicit learning: an event-related FMRI study

The medial temporal lobe (MTL) has been associated with declarative learning of flexible relational rules and the basal ganglia with implicit learning of stimulus-response mappings. It remains an open question of whether MTL or basal ganglia are involved when learning flexible relational contingencies without awareness. We studied learning of an explicit stimulus-response association with fMRI. Embedded in this explicit task was a hidden structure that was learnt implicitly. Implicit learning of the sequential regularities of the "hidden rule" activated the ventral perirhinal cortex, within the MTL, whereas learning the fixed stimulus-response associations activated the basal ganglia, indicating that the function of the MTL and the basal ganglia depends on the learned material and not necessarily on the participants' awareness.     

GeneBins: a database for classifying gene expression data,with application to plant genome arrays

Background  

To interpret microarray experiments, several ontological analysis tools have been developed. However, current tools are limited to specific organisms.     

Extending MapMan: application to legume genome arrays

MOTIVATION: Based on a gene classification into hierarchical categories ('BINs'), MapMan was originally developed to display Arabidopsis thaliana gene expression in a functional context. We have created a bioinformatics system to extend MapMan to any organism by using a new BIN structure based on the KEGG database. Gene sequences are assigned to this ontology by homology relationships in four reference databases: KEGG, COG, Swiss-Prot and Gene Ontology. We applied this system to tailor MapMan to the GeneChips of two model legumes, Glycine max and Medicago truncatula. We also developed a module to identify the most relevant pathways involved. AVAILABILITY: All mapping files, pathway pictures and the analysis method are available at http://bioinfoserver.rsbs.anu.edu.au/     

Involving Motor Capabilities in the Formation of Sensory Space Representations

A goal of sensory coding is to capture features of sensory input that are behaviorally relevant. Therefore, a generic principle of sensory coding should take into account the motor capabilities of an agent. Up to now, unsupervised learning of sensory representations with respect to generic coding principles has been limited to passively received sensory input. Here we propose an algorithm that reorganizes an agent''s representation of sensory space by maximizing the predictability of sensory state transitions given a motor action. We applied the algorithm to the sensory spaces of a number of simple, simulated agents with different motor parameters, moving in two-dimensional mazes. We find that the optimization algorithm generates compact, isotropic representations of space, comparable to hippocampal place fields. As expected, the size and spatial distribution of these place fields-like representations adapt to the motor parameters of the agent as well as to its environment. The representations prove to be well suited as a basis for path planning and navigation. They not only possess a high degree of state-transition predictability, but also are temporally stable. We conclude that the coding principle of predictability is a promising candidate for understanding place field formation as the result of sensorimotor reorganization.     

A nucleotide insertion and frameshift cause albumin Kénitra, an extended and O-glycosylated mutant of human serum albumin with two additional disulfide bridges.

Albumin Kenitra is a new type of genetic variant of human serum albumin that has been found in two members of a family of Sephardic Jews from Kenitra (Morocco). The slow-migrating variant and the normal protein were isolated by anion-exchange chromatography and, after treatment with CNBr, the digests were analyzed by two-dimensional electrophoresis in a polyacrylamide gel. The CNBr peptides of the variant were purified by reverse-phase high performance liquid chromatography and submitted to sequence analysis. Albumin Kenitra is peculiar because it has an elongated polypeptide chain, 601 residues instead of 585, and its sequence is modified beginning from residue 575. DNA structural studies showed that the variant is caused by a single-base insertion, an adenine at nucleotide position 15 970 in the genomic sequence, which leads to a frameshift with the subsequent translation to the first termination codon of exon 15. Mass spectrometric analyses revealed that the four additional cysteine residues of the variant form two new S-S bridges and showed that albumin Kenitra is partially O-glycosylated by a monosialylated HexHexNAc structure. This oligosaccharide chain has been located to Thr596 by amino-acid sequence analysis of the tryptic fragment 592-597.     

Continuous glucose monitoring in cystic fibrosis patients according to the glucose tolerance.

Cystic fibrosis (CF) is associated with a long preclinical state of abnormal glucose tolerance. The aim of this study was (i) to evaluate the profile of glucose tolerance in young adults with CF and (ii) to compare these results with those obtained by a continuous subcutaneous glucose monitoring (CGMS). CF subjects with fasting glycemia inferior to 126 mg/dl were included in the study. An oral glucose tolerance test (OGTT) identified the subjects either with a normal glucose tolerance (NGT), or impaired glucose tolerance (IGT), or diabetes. CGMS (Medtronic) was performed during 3 days to analyze mean glucose level, high glucose excursions, and glucose area under the curve (AUC). Forty-nine patients were included in the study. NGT (n=22), IGT (n=17), and diabetes groups (n=10) were comparable except with regard to age and BMI (p<0.001). HbA1c values in diabetes group were significantly higher (p<0.001) than in NGT and IGT groups. CGMS revealed peaks of glucose values superior to 200 mg/dl at least once after a meal in 8 patients (36%) with NGT, in 9 patients (52%) with IGT, and in all patients with diabetes (p<0.01). Mean CGMS glucose and glucose AUC values increased in patients with diabetes compared to patients with NGT and IGT (p<0.05). Peak of CGMS glucose reached 182+/-60 mg/dl in NGT group despite the normal glucose profile at OGTT. In conclusion, CGMS revealed pathological glucose excursions not only in patients with impaired glucose tolerance at OGTT but also in patients with a normal glycemic profile. CGMS could be a useful tool for the early detection of hyperglycemia in patients with CF.     

A GC cluster repeat is a hotspot for mit- macro-deletions in yeast mitochondrial DNA.

Summary In a random collection of mit^– mutations of the yeast strain 777-3A we find that deletions are exceptionally frequent in the OXI3 gene, a large mosaic gene coding for subunit I of cytochrome oxidase. About 10% of all oxi3 ^– mutants carry the same macro-deletion, del-A, extending from the 5 non-translated leader of OXI3 to intron 5b of this gene. Determination of the respective wild-type sequences and of the del-A junction sequence revealed that the end-points of the deletion are in two GC clusters with 31 by sequence identity which are located at a distance of 11.3 kb. We speculate that not only the sequence identity of the two GC clusters but also the palindromic structure of these putatively mobile elements of yeast mitochondrial DNA (mtDNA) plays a role in deletion formation.