Bicyclo[2.2.1]heptanes as novel triple re-uptake inhibitors for the treatment of depression

A series of substituted naphthyl containing chiral [2.2.1] bicycloheptanes were prepared utilizing asymmetric Diels-Alder chemistry. This paper describes structure-activity relationships in this series. The N-methyl 2-naphthyl analogue (16d) and its des-methyl analogue (17d) are active triple re-uptake inhibitors both in vivo and in vitro.     

Global co-existence of two evolutionary lineages of parvovirus b19 1a, different in genome-wide synonymous positions

Parvovirus B19 (B19V) can cause infection in humans. To date, three genotypes of B19V, with subtypes, are known, of which genotype 1a is the most prevalent genotype in the Western world. We sequenced the genome of B19V strains of 65 asymptomatic, recently infected Dutch blood donors, to investigate the spatio-temporal distribution of B19V strains, in the years 2003-2009. The sequences were compared to B19V sequences from Dutch patients with fifth disease, and to global B19V sequences as available from GenBank. All Dutch B19V strains belonged to genotype 1a. Phylogenetic analysis of the strains from Dutch blood donors showed that two groups of genotype 1a co-exist. A clear-cut division into the two groups was also found among the B19V strains from Dutch patients, and among the B19V sequences in GenBank. The two groups of genotype 1a co-exist around the world and do not appear to differ in their ability to cause disease. Strikingly, the two groups of B19V predominantly differ in synonymous mutations, distributed throughout the entire genome of B19V. We propose to call the two groups of B19V genotype 1a respectively subtype 1a1 and 1a2.     

Phenotypic plasticity in response to nitrate supply of an inherently fast-growing species from a fertile habitat and an inherently slow-growing species from an infertile habitat

The aim of the present study was to investigate possible differences in plasticity between a potentially fast-growing and a potentially slow-growing grass species. To this end, Holcus lanatus (L.) and Deschampsia flexuosa (L.) Trin., associated with fertile and infertile habitats, respectively, were grown in sand at eight nitrate concentrations. When plants obtained a fresh weight of approximately 5 g, biomass allocation, specific leaf area, the rate of net photosynthesis, the organic nitrogen concentration of various plant parts and the root weight at different soil depths were determined. There were linear relationships between the morphological and physiological features studied and the In-transformed nitrate concentration supplied, except for the specific leaf area and root nitrogen concentration of H. lanatus, which did not respond to the nitrate concentration. The root biomass of H. lanatus was invariably distributed over the soil layers than that of D. flexuosa. However, D. flexuosa allocated more root biomass to lower soil depths with decreasing nitrate concentration, in contrast to H. lanatus, which did not respond. The relative response to nitrate supply, i.e. the value of a character at a certain nitrate level relative to the value of that character at the highest nitrate supply, was used as a measure for plasticity. For a number of parameters (leaf area ratio, root weight ratio, root nitrogen concentration, vertical root biomass distribution and rate of net photosynthesis per unit leaf weight) the potentially slow-growing D. flexuosa exhibited a higher phenotypic plasticity than the potentially fast-growing H. lanatus. These findings are in disagreement with current literature. Possible explanations for this discrepancy are discussed in terms of differences in experimental approach as well as fundamental differences in specific traits between fast- and slow-growing grasses.     

The Relationship between Intelligence and Training Gains Is Moderated by Training Strategy

We examined the relationship between training regimen and fluid intelligence in the learning of a complex video game. Fifty non-game-playing young adults were trained on a game called Space Fortress for 30 hours with one of two training regimens: 1) Hybrid Variable-Priority Training (HVT), with part-task training and a focus on improving specific skills and managing task priorities, and 2) Full Emphasis Training (FET) in which participants practiced the whole game to obtain the highest overall score. Fluid intelligence was measured with the Raven’s Progressive Matrix task before training. With FET, fluid intelligence was positively associated with learning, suggesting that intellectual ability played a substantial role in determining individual differences in training success. In contrast, with HVT, fluid intelligence was not associated with learning, suggesting that individual differences in fluid intelligence do not factor into training success in a regimen that emphasizes component tasks and flexible task coordination. By analyzing training effects in terms of individual differences and training regimens, the current study offers a training approach that minimizes the potentially limiting effect of individual differences.     

Insertion of leader peptidase into the thylakoid membrane during synthesis in a chloroplast translation system

The mechanisms of targeting and insertion of chloroplast-encoded thylakoid membrane proteins are poorly understood. In this study, we have used a translation system isolated from chloroplasts to begin to investigate these mechanisms. The bacterial membrane protein leader peptidase (Lep) was used as a model protein because its targeting and insertion mechanisms are well understood for Escherichia coli and for the endoplasmic reticulum. Lep could thus provide insight into the functional homologies between the different membrane systems. Lep was efficiently expressed in the chloroplast translation system, and the protein could be inserted into thylakoid membranes with the same topology as in E. coli cytoplasmic membranes, following the positive-inside rule. Insertion of Lep into the thylakoid membrane was stimulated by the trans-thylakoid proton gradient and was strongly inhibited by azide, suggesting a requirement for SecA activity. Insertion most likely occurred in a cotranslational manner, because insertion could only be observed if thylakoid membranes were present during translation reactions but not when thylakoid membranes were added after translation reactions were terminated. To halt the elongation process at different stages, we translated truncated Lep mRNAs without a stop codon, resulting in the formation of stable ribosome nascent chain complexes. These complexes showed a strong, salt-resistant affinity for the thylakoid membrane, implying a functional interaction of the ribosome with the membrane and supporting a cotranslational insertion mechanism for Lep. Our study supports a functional homology for the insertion of Lep into the thylakoid membrane and the E. coli cytoplasmic membrane.     

Transglycosidase activity of chitotriosidase: improved enzymatic assay for the human macrophage chitinase

Chitotriosidase is a chitinase that is massively expressed by lipid-laden tissue macrophages in man. Its enzymatic activity is markedly elevated in serum of patients suffering from lysosomal lipid storage disorders, sarcoidosis, thalassemia, and visceral Leishmaniasis. Monitoring of serum chitotriosidase activity in Gaucher disease patients during progression and therapeutic correction of their disease is useful to obtain insight in changes in body burden on pathological macrophages. However, accurate quantification of chitotriosidase levels by enzyme assay is complicated by apparent substrate inhibition, which prohibits the use of saturating substrate concentrations. We have therefore studied the catalytic features of chitotriosidase in more detail. It is demonstrated that the inhibition of enzyme activity at excess substrate concentration can be fully explained by transglycosylation of substrate molecules. The potential physiological consequences of the ability of chitotriosidase to hydrolyze as well as transglycosylate are discussed. The novel insight in transglycosidase activity of chitotriosidase has led to the design of a new substrate molecule, 4-methylumbelliferyl-(4-deoxy)chitobiose. With this substrate, which is no acceptor for transglycosylation, chitotriosidase shows normal Michaelis-Menten kinetics, resulting in major improvements in sensitivity and reproducibility of enzymatic activity measurements. The novel convenient chitotriosidase enzyme assay should facilitate the accurate monitoring of Gaucher disease patients receiving costly enzyme replacement therapy.     

Comparison of assays for antibodies to Encephalitozoon cuniculi in rabbits

Two indirect immunofluorescence (IIF) assays, two enzyme-linked immunosorbent assays (ELISAs) and the carbon immunoassay (CIA) for determination of antibodies to Encephalitozoon cuniculi were compared using 210 sera of rabbits, 135 of which originated from seven infected colonies, while 75 originated from four uninfected colonies. There was no evidence of a difference between the different assays with respect to the number of positive sera. There was a clear correlation between the quantitative response measured by IIF and CIA and the other assays, and between both IIF tests, while no such correlation was found in the quantitative response measured by ELISAs, which might be explained by the less quantitative nature of the ELISA. Therefore quantitative determination of antibodies to E. cuniculi should be performed by IIF and not by ELISA. The nosographic sensitivities N1 and specificities N2 of the assays were > or = 0.94 and > or = 0.97 respectively. Small differences in N1 and N2 between the assays, although not statistically significant, were responsible for differences in the calculated predictive values of a positive test and of a negative test. As expected, the magnitude of these differences depended on the fraction of positive sera sampled from a given colony. There was strong evidence of such a difference between the fraction of positive sera found in different colonies, but the sample size from some colonies was too small to allow any conclusion, whether this was due to differences in the prevalences of the infection in the colonies or something else. We conclude that any of the assays will be suitable for the routine health monitoring of laboratory rabbit colonies for E. cuniculi infection, as recommended by the Federation of European Laboratory Animal Science Associations.     

Is the Effect of Aerobic Exercise on Cognition a Placebo Effect?

A number of studies and meta-analyses conclude that aerobic fitness (walking) interventions improve cognition. Such interventions typically compare improvements from these interventions to an active control group in which participants engage in non-aerobic activities (typically stretching and toning) for an equivalent amount of time. However, in the absence of a double-blind design, the presence of an active control group does not necessarily control for placebo effects; participants might expect different amounts of improvement for the treatment and control interventions [1]. We conducted a large survey to explore whether people expect greater cognitive benefits from an aerobic exercise intervention compared to a control intervention. If participants expect greater improvement following aerobic exercise, then the benefits of such interventions might be due in part to a placebo effect. In general, expectations did not differ between aerobic and non-aerobic interventions. If anything, some of the results suggest the opposite (e.g., respondents expected the control, non-aerobic intervention to yield bigger memory gains). These results provide the first evidence that cognitive improvements following aerobic fitness training are not due to differential expectations.     

Auxin distribution in Lotus japonicus during root nodule development

For this work, Lotus japonicus transgenic plants were constructed expressing a fusion reporter gene consisting of the genes beta-glucuronidase (gus) and green fluorescent protein (gfp) under control of the soybean auxin-responsive promoter GH3. These plants expressed GUS and GFP in the vascular bundle of shoots, roots and leafs. Root sections showed that in mature parts of the roots GUS is mainly expressed in phloem and vascular parenchyma of the vascular cylinder. By detecting GUS activity, we describe the auxin distribution pattern in the root of the determinate nodulating legume L. japonicus during the development of nodulation and also after inoculation with purified Nod factors, N-naphthylphthalamic acid (NPA) and indoleacetic acid (IAA). Differently than white clover, which forms indeterminate nodules, L. japonicus presented a strong GUS activity at the dividing outer cortical cells during the first nodule cell divisions. This suggests different auxin distribution pattern between the determinate and indeterminate nodulating legumes that may be responsible of the differences in nodule development between these groups. By measuring of the GFP fluorescence expressed 21 days after treatment with Nod factors or bacteria we were able to quantify the differences in GH3 expression levels in single living roots. In order to correlate these data with auxin transport capacity we measured the auxin transport levels by a previously described radioactive method. At 48 h after inoculation with Nod factors, auxin transport showed to be increased in the middle root segment. The results obtained indicate that L. japonicus transformed lines expressing the GFP and GUS reporters under the control of the GH3 promoter are suitable for the study of auxin distribution in this legume.