The Preprotein Binding Domain of SecA Displays Intrinsic Rotational Dynamics

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Improved BM212 MmpL3 Inhibitor Analogue Shows Efficacy in Acute Murine Model of Tuberculosis Infection

1,5-Diphenyl pyrroles were previously identified as a class of compounds endowed with high in vitro efficacy against M. tuberculosis. To improve the physical chemical properties and drug-like parameters of this class of compounds, a medicinal chemistry effort was undertaken. By selecting the optimal substitution patterns for the phenyl rings at N1 and C5 and by replacing the thiomorpholine moiety with a morpholine one, a new series of compounds was produced. The replacement of the sulfur with oxygen gave compounds with lower lipophilicity and improved in vitro microsomal stability. Moreover, since the parent compound of this family has been shown to target MmpL3, mycobacterial mutants resistant to two compounds have been isolated and characterized by sequencing the mmpL3 gene; all the mutants showed point mutations in this gene. The best compound identified to date was progressed to dose-response studies in an acute murine TB infection model. The resulting ED₉₉ of 49 mg/Kg is within the range of commonly employed tuberculosis drugs, demonstrating the potential of this chemical series. The in vitro and in vivo target validation evidence presented here adds further weight to MmpL3 as a druggable target of interest for anti-tubercular drug discovery.     

Phylogeographic patterns, genetic affinities and morphological differentiation between Epipactis helleborine and related lineages in a Mediterranean glacial refugium

Background and Aims

In the Mediterranean basin, the Italian peninsula has been suggested to be one of the most important glacial refugia for temperate tree species. The orchid genus Epipactis is widely represented in the Italian peninsula by widespread species and several endemic, localized taxa, including selfing and outcrossing taxa. Here the phylogenetic and phylogeographic relationships in a group of closely related taxa in Epipactis are investigated with the aim of understanding the role of this refugial area for cladogenesis and speciation in herbaceous species, such as terrestrial orchids.

Methods

Ribosomal DNA (rDNA) was employed to assess phylogenetic relationships, and plastid sequence variation in the rbcL–accD spacer was used to reveal phylogeographic patterns among plastid haplotypes using a parsimony network.

Key Results

Low genetic variation and shared ribotypes were detected in rDNA, whereas high levels of sequence variation and a strong phylogeographic structure were found in the examined plastid region. The parsimony plastid haplotype network identified two main haplotype groups, one including E. atrorubens/microphylla/muelleri/leptochila and the other including all accessions of E. helleborine and several localized and endemic taxa, with a combination of widespread and rare haplotypes detected across the Italian peninsula. A greater genetic divergence separated the Italian and other European accessions of E. helleborine.

Conclusions

Phylogenetic and phylogeographic patterns support a working hypothesis in which the Italian peninsula has only recently been colonized by Epipactis, probably during the most recent phase of the Quaternary age and, nevertheless, it acted as a remarkable centre of diversification for this orchid lineage. Changes in pollination strategy and recurrent shifts in mating system (from allogamy to autogamy) could have represented the mechanism promoting this rapid diversification and the observed high taxonomic complexity detected in the E. helleborine species complex.     

Inherited Glutathione Reductase Deficiency and Plasmodium falciparum Malaria—A Case Study

In Plasmodium falciparum-infected red blood cells (RBCs), the flavoenzyme glutathione reductase (GR) regenerates reduced glutathione, which is essential for antioxidant defense. GR utilizes NADPH produced in the pentose phosphate shunt by glucose-6-phosphate dehydrogenase (G6PD). Thus, conditions affecting host G6PD or GR induce increased sensitivity to oxidants. Hereditary G6PD deficiency is frequent in malaria endemic areas and provides protection against severe malaria. Furthermore, GR deficiency resulting from insufficient saturation of the enzyme with its prosthetic group FAD is common. Based on these naturally occurring phenomena, GR of malaria parasites and their host cells represent attractive antimalarial drug targets. Recently we were given the opportunity to examine invasion, growth, and drug sensitivity of three P. falciparum strains (3D7, K1, and Palo Alto) in the RBCs from three homozygous individuals with total GR deficiency resulting from mutations in the apoprotein. Invasion or growth in the GR-deficient RBCs was not impaired for any of the parasite strains tested. Drug sensitivity to chloroquine, artemisinin, and methylene blue was comparable to parasites grown in GR-sufficient RBCs and sensitivity towards paraquat and sodium nitroprusside was only slightly enhanced. In contrast, membrane deposition of hemichromes as well as the opsonizing complement C3b fragments and phagocytosis were strongly increased in ring-infected RBCs of the GR-deficient individuals compared to ring-infected normal RBCs. Also, in one of the individuals, membrane-bound autologous IgGs were significantly enhanced. Thus, based on our in vitro data, GR deficiency and drug-induced GR inhibition may protect from malaria by inducing enhanced ring stage phagocytosis rather than by impairing parasite growth directly.     

Alcohol Consumption in Midlife and Cognitive Performance Assessed 13 Years Later in the SU.VI.MAX 2 Cohort

Background

Associations between alcohol consumption and cognitive function are discordant and data focusing on midlife exposure are scarce.

Objective

To estimate the association between midlife alcohol consumption and cognitive performance assessed 13 y later while accounting for comorbidities and diet.

Methods

3,088 French middle-aged adults included in the SU.VI.MAX (1994) study with available neuropsychological evaluation 13 y later. Data on alcohol consumption were obtained from repeated 24h dietary records collected in 1994–1996. Cognitive performance was assessed in 2007–2009 via a battery of 6 neuropsychological tests. A composite score was built as the mean of the standardized individual test scores (mean = 50, SD = 10). ANCOVA were performed to estimate mean differences in cognitive performance and 95% confidence intervals (CI).

Results

In women, abstainers displayed lower cognitive scores than did low-to-moderate alcohol drinkers (1 to 2 drinks/day) (mean difference = −1.77; 95% CI: −3.29, −0.25). In men, heavy drinkers (>3 drinks/day) had higher cognitive scores than did low-to-moderate (1 to 3 drinks/day) (mean difference = 1.05; 95% CI: 0.10, 1.99). However, a lower composite cognitive score was detected in male drinkers consuming ≥90 g/d (≈8 drinks/d). A higher proportion of alcohol intake from beer was also associated with lower cognitive scores. These associations remained significant after adjustment for diet, comorbidities and sociodemographic factors.

Conclusion

In men, heavy but not extreme drinking was associated with higher global cognitive scores. Given the known harmful effects of alcohol even in low doses regarding risk of cancer, the study does not provide a basis for modifying current public health messages.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00272428","term_id":"NCT00272428"}}NCT00272428     

Walking but not barking improves verb recovery: implications for action observation treatment in aphasia rehabilitation

Recent studies have shown that action observation treatment without concomitant verbal cue has a positive impact on the recovery of verb retrieval deficits in aphasic patients. In agreement with an embodied cognition viewpoint, a hypothesis has been advanced that gestures and language form a single communication system and words whose retrieval is facilitated by gestures are semantically represented through sensory-motor features. However, it is still an open question as to what extent this treatment approach works. Results from the recovery of motor deficits have suggested that action observation promotes motor recovery only for actions that are part of the motor repertoire of the observer. The aim of the present experiment was to further investigate the role of action observation treatment in verb recovery. In particular, we contrasted the effects induced by observing human actions (e.g. dancing, kicking, pointing, eating) versus non human actions (e.g. barking, printing). Seven chronic aphasic patients with a selective deficit in verb retrieval underwent an intensive rehabilitation training that included five daily sessions over two consecutive weeks. Each subject was asked to carefully observe 115 video-clips of actions, one at a time and, after observing them, they had to produce the corresponding verb. Two groups of actions were randomly presented: humans versus nonhuman actions. In all patients, significant improvement in verb retrieval was found only by observing video-clips of human actions. Moreover, follow-up testing revealed long-term verb recovery that was still present two months after the two treatments had ended. In support of the multimodal concept representation's proposal, we suggest that just the observation of actions pertaining to the human motor repertoire is an effective rehabilitation approach for verb recovery.     

Structure and function of vertebrate CMP-sialic acid synthetases

Activation of sugars into nucleotide sugars is critical for their entry into biosynthetic pathways. In eukaryotic cells, the activation of the acidic nine-carbon sugar sialic acid to CMP-sialic acid takes place in the cell nucleus, whereas all other nucleotide sugars are made in the cytoplasm. Molecular cloning of vertebrate CMP-sialic acid synthetases confirmed the nuclear localization and introduced new molecular tools for directly exploring the functional mechanisms of the enzymes, as well as the physiological relevance of their nuclear transport. Although major advances have been made in understanding structure-function relationships and defining elements involved in the nuclear transport, the riddle surrounding the physiological relevance of nuclear localization awaits resolution.