Synchronization and Propagation of Global Sleep Spindles

Sleep spindles occur thousands of times during normal sleep and can be easily detected by visual inspection of EEG signals. These characteristics make spindles one of the most studied EEG structures in mammalian sleep. In this work we considered global spindles, which are spindles that are observed simultaneously in all EEG channels. We propose a methodology that investigates both the signal envelope and phase/frequency of each global spindle. By analysing the global spindle phase we showed that 90% of spindles synchronize with an average latency time of 0.1 s. We also measured the frequency modulation (chirp) of global spindles and found that global spindle chirp and synchronization are not correlated. By investigating the signal envelopes and implementing a homogeneous and isotropic propagation model, we could estimate both the signal origin and velocity in global spindles. Our results indicate that this simple and non-invasive approach could determine with reasonable precision the spindle origin, and allowed us to estimate a signal speed of 0.12 m/s. Finally, we consider whether synchronization might be useful as a non-invasive diagnostic tool.     

HIV-1 Diversity,Transmission Dynamics and Primary Drug Resistance in Angola

Objectives

To assess HIV-1 diversity, transmission dynamics and prevalence of transmitted drug resistance (TDR) in Angola, five years after ART scale-up.

Methods

Population sequencing of the pol gene was performed on 139 plasma samples collected in 2009 from drug-naive HIV-1 infected individuals living in Luanda. HIV-1 subtypes were determined using phylogenetic analysis. Drug resistance mutations were identified using the Calibrated Population Resistance Tool (CPR). Transmission networks were determined using phylogenetic analysis of all Angolan sequences present in the databases. Evolutionary trends were determined by comparison with a similar survey performed in 2001.

Results

47.1% of the viruses were pure subtypes (all except B), 47.1% were recombinants and 5.8% were untypable. The prevalence of subtype A decreased significantly from 2001 to 2009 (40.0% to 10.8%, P = 0.0019) while the prevalence of unique recombinant forms (URFs) increased>2-fold (40.0% to 83.1%, P<0.0001). The most frequent URFs comprised untypable sequences with subtypes H (U/H, n = 7, 10.8%), A (U/A, n = 6, 9.2%) and G (G/U, n = 4, 6.2%). Newly identified U/H recombinants formed a highly supported monophyletic cluster suggesting a local and common origin. TDR mutation K103N was found in one (0.7%) patient (1.6% in 2001). Out of the 364 sequences sampled for transmission network analysis, 130 (35.7%) were part of a transmission network. Forty eight transmission clusters were identified; the majority (56.3%) comprised sequences sampled in 2008–2010 in Luanda which is consistent with a locally fuelled epidemic. Very low genetic distance was found in 27 transmission pairs sampled in the same year, suggesting recent transmission events.

Conclusions

Transmission of drug resistant strains was still negligible in Luanda in 2009, five years after the scale-up of ART. The dominance of small and recent transmission clusters and the emergence of new URFs are consistent with a rising HIV-1 epidemics mainly driven by heterosexual transmission.     

(+/-)-cis-(6-Ethyl-tetrahydropyran-2-yl)-formic acid: a novel substance with antinociceptive properties

We described in this paper the first synthesis to the (+/-) cis (6-ethyl-tetrahydropyran-2-yl) formic acid (1) using the very efficient Prins cyclization reaction as strategy to construction of its tetrahydropyran skeleton. This new compound presented a significant antinociceptive property by the tail-flick model.     

<Emphasis Type="Italic">Anemia tomentosa</Emphasis> var. <Emphasis Type="Italic">anthriscifolia</Emphasis> in vitro culture: sporophyte development and volatile compound profile of an aromatic fern

Anemia tomentosa var. anthriscifolia is an aromatic fern with a pleasant woody aroma and antimycobacterial activity. In this paper, we describe for the first time its spore-derived gametophyte development and the effect of indole-3-acetic acid and jasmonic acid on in vitro gametophyte/sporophyte development, as well as volatile compound production. Volatiles were obtained by simultaneous distillation and extraction (SDE) and analyzed by high resolution gas chromatography coupled with mass spectrometry. Spore-derived gametophytes were able to develop into sporophytes independently of the media culture composition, even when no plant growth regulator was added. Fifty different substances were detected in all in vitro A. tomentosa SDE extracts, while 20 were detected in the wild SDE plant extract. Monoterpenes were more prevalent (69.8–89.8%) than sesquiterpenes (9.4–28.7%) in in vitro plants, while sesquiterpenes represent 97.5% of the volatiles produced by the wild-grown plants. The major monoterpene components in in vitro plants were α-pinene (9.3–24.3%), trans-pinocarveol (20.6–27.9%), pinocarvone (15.4–25.1%) and myrtenyl acetate (6.4–12.3%). The triquinane sesquiterpenes silphiperfol-6-ene (0.6–2.9%), α-guaiene (0.5–2.5%), β-barbatene (1.1–3.9%) and 9-epi-presilphiperfolan-1-ol (2.5–5.6%) represent the most abundant sesquiterpenes. The changes in the monoterpene/sesquiterpene rates between micropropagated and wild plants are not related to the presence of JA or IAA in the media culture. Further studies are still needed to obtain a complete understanding of the factors leading to these results, which could be related to differences in the irradiance levels of in vitro plants versus those from a wild environment, as well as the developmental stage of the plants. This is the first report of the use of plant growth regulators on Anemia tomentosa in vitro culture development and their effects on volatile profiles.     

Genetic characterization of Listeria monocytogenes food isolates and pathogenic potential within serovars 1/2a and 1/2b

A total of 39 Listeria monocytogenes strains isolated from raw milk, smoked meat, chicken carcass and reference strains, belonging to serovars 1/2a, 4a, 1/2b, 3b and 4b, were analysed by RAPD and by polymorphisms of the virulent genes inlAB and iap. Ten isolates, belonging to serovars 1/2a and 1/2b and, collected from raw milk and smoked meat, were further tested for pathogenicity by IP injection into mice. The clustering of the 39 L. monocytogenes strains in 3 groups at 0.45 similarity level, based on molecular typing, was observed. Distribution of serovars in these clusters was in agreement with the proposed three Listeria monocytogenes lineages. Within serovar 1/2b, the 50% lethal dose (LD50) ranged from 8.4 x 10(4) to 1.7 x 10(6) cfu.ml(-1). One of the serovar 1/2b strains, isolated from smoked meat, exhibited the lowest virulence potential evaluated by LD50 and by mean time to death (MTD) and, from this point of view, was completely different from the other strains. Our results suggest the existence of heterogeneity in virulence levels within serovars 1/2a and 1/2b. However, when comparing the isolates based on genotyping, virulence indicators and food origin, no relation could be assessed.     

The role of glucose metabolism and insulin resistance in cardiac remodelling induced by cigarette smoke exposure

The aim of this study is to evaluate whether the alterations in glucose metabolism and insulin resistance are mechanisms presented in cardiac remodelling induced by the toxicity of cigarette smoke. Male Wistar rats were assigned to the control group (C; n = 12) and the cigarette smoke-exposed group (exposed to cigarette smoke over 2 months) (CS; n = 12). Transthoracic echocardiography, blood pressure assessment, serum biochemical analyses for catecholamines and cotinine, energy metabolism enzymes activities assay; HOMA index (homeostatic model assessment); immunohistochemistry; and Western blot for proteins involved in energy metabolism were performed. The CS group presented concentric hypertrophy, systolic and diastolic dysfunction, and higher oxidative stress. It was observed changes in energy metabolism, characterized by a higher HOMA index, lower concentration of GLUT4 (glucose transporter 4) and lower 3-hydroxyl-CoA dehydrogenase activity, suggesting the presence of insulin resistance. Yet, the cardiac glycogen was depleted, phosphofructokinase (PFK) and lactate dehydrogenase (LDH) increased, with normal pyruvate dehydrogenase (PDH) activity. The activity of citrate synthase, mitochondrial complexes and ATP synthase (adenosine triphosphate synthase) decreased and the expression of Sirtuin 1 (SIRT1) increased. In conclusion, exposure to cigarette smoke induces cardiac remodelling and dysfunction. The mitochondrial dysfunction and heart damage induced by cigarette smoke exposure are associated with insulin resistance and glucose metabolism changes.     

The HET-s prion protein of the filamentous fungus Podospora anserina aggregates in vitro into amyloid-like fibrils.

The HET-s protein of Podospora anserina is a fungal prion. This protein behaves as an infectious cytoplasmic element that is transmitted horizontally from one strain to another. Under the prion form, the HET-s protein forms aggregates in vivo. The specificity of this prion model compared with the yeast prions resides in the fact that under the prion form HET-s causes a growth inhibition and cell death reaction when co-expressed with the HET-S protein from which it differs by 13 residues. Herein we describe the purification and initial characterization of recombinant HET-s protein expressed in Escherichia coli. The HET-s protein self-associates over time into high molecular weight aggregates. These aggregates greatly accelerate precipitation of the soluble form. HET-s aggregates appear as amyloid-like fibrils using electron microscopy. They bind Congo Red and show birefringence under polarized light. In the aggregated form, a HET-s fragment of approximately 7 kDa is resistant to proteinase K digestion. CD and FTIR analyses indicate that upon transition to the aggregated state, the HET-s protein undergoes a structural rearrangement characterized by an increase in antiparallel beta-sheet structure content. These results suggest that the [Het-s] prion element propagates in vivo as an infectious amyloid.