Exploring the Factor Structure of Neurocognitive Measures in Older Individuals

Here we focus on factor analysis from a best practices point of view, by investigating the factor structure of neuropsychological tests and using the results obtained to illustrate on choosing a reasonable solution. The sample (n=1051 individuals) was randomly divided into two groups: one for exploratory factor analysis (EFA) and principal component analysis (PCA), to investigate the number of factors underlying the neurocognitive variables; the second to test the “best fit” model via confirmatory factor analysis (CFA). For the exploratory step, three extraction (maximum likelihood, principal axis factoring and principal components) and two rotation (orthogonal and oblique) methods were used. The analysis methodology allowed exploring how different cognitive/psychological tests correlated/discriminated between dimensions, indicating that to capture latent structures in similar sample sizes and measures, with approximately normal data distribution, reflective models with oblimin rotation might prove the most adequate.     

A Y639F/H784A T7 RNA polymerase double mutant displays superior properties for synthesizing RNAs with non-canonical NTPs

A T7 RNA polymerase in which Tyr639 is mutated to Phe readily utilizes 2′-deoxy, 2′-NH₂ and 2′-F NTPs as substrates and has been widely used to synthesize modified RNAs for a variety of applications. This mutant does not readily utilize NTPs with bulkier 2′-substituents, nor does it facilitate incorporation of NTPs with modifications at other positions. Introduction of a second mutation (H784A) into the Y639F background markedly enhances utilization of NTPs with bulky 2′-substituents (2′-OMe and 2′-N₃), and may also enhance use of NTPs with modifications at other than the 2′-position. The Y639F/H784A double mutant may therefore be exceptionally useful for incorporation of a variety of non-canonical NMPs into RNA.     

Entire hemithorax irradiation for Masaoka stage IVa thymomas

Thymomas are rare neoplasms that have an indolent growth with a preferentially intra-thoracic dissemination pattern. Surgery is currently the standard treatment of thymomas; however radiotherapy is often used in an adjuvant setting due to a high sensitivity of these tumors to such treatment. Postoperative entire hemithoracic irradiation has been used in selected Masaoka stage IVa cases after complete surgical excision of metastatic lesions.In the present article, the authors report three cases of Masaoka stage IVa thymoma that underwent entire hemithorax irradiation after surgical excision of metastatic lesions. The first two patients presented as stage IVa thymomas. The third case consisted of a pleural recurrence of a thymoma.Hemithoracic irradiation with low doses has been used by different authors; the available data shows that it is a well-tolerated treatment that could potentially lead to better loco-regional control and increased overall survival.     

Isoproterenol-induced intramembrane particle aggregation and water flux in toad epidermis

Stimulation of toad skin with isproterenol resulted in a dramatic increase in water flow, and in the appearance of aggregates of intramembrane particles in the apical membrane of granular cells of the replacement layer, just beneath the stratum corneum. This membrane structural modification appears to be a general prerequisite for the change in water permeability of vasopressin-sensitive epithelia.     

Autoregulation allows Escherichia coli RNase E to adjust continuously its synthesis to that of its substrates

The Escherichia coli endonuclease RNase E plays a key role in rRNA maturation and mRNA decay. In particular, it controls the decay of its own mRNA by cleaving it within the 5'-untranslated region (UTR), thereby autoregulating its synthesis. Here, we report that, when the synthesis of an RNase E substrate is artificially induced to high levels in vivo, both the rne mRNA concentration and RNase E synthesis increase abruptly and then decrease to a steady-state level that remains higher than in the absence of induction. Using rne-lacZ fusions that retain or lack the rne 5'UTR, we show that these variations reflect a transient mRNA stabilization mediated by the rne 5'UTR. Finally, by putting RNase E synthesis under the control of an IPTG-controlled promoter, we show that a similar, rne 5'UTR-mediated mRNA stabilization can result from a shortage of RNase E. We conclude that the burst in substrate synthesis has titrated RNase E, stabilizing the rne mRNA by protecting its 5'UTR. However, this stabilization is self-correcting, because it allows the RNase E pool to expand until its mRNA is destabilized again. Thus, autoregulation allows RNase E to adjust its synthesis to that of its substrates, a behaviour that may be common among autoregulated proteins. Incidentally, this adjustment cannot occur when translation is blocked, and we argue that the global mRNA stabilization observed under these conditions originates in part from this defect.     

Compared chemical properties of dermonecrotic and lethal toxins from spiders of the genusLoxosceles (Araneae)

Loxosceles spider venom usually causes a typical dermonecrotic lesion in bitten patients, but it may also cause systemic effects that may be lethal. Gel filtration on Sephadex G-100 ofLoxosceles gaucho, L. laeta, orL. intermedia spider venoms resulted in three fractions (A, containing higher molecular mass components, B containing intermediate molecular mass components, and C with lower molecular mass components). The dermonecrotic and lethal activities were detected exclusively in fraction A of all three species. Analysis by SDS-PAGE showed that the major protein contained in fraction A has molecular weight approximately 35 kDa inL. gaucho andL. intermedia, but 32 kDa inL. laeta venom. These toxins were isolated from venoms ofL. gaucho, L. laeta, andL. intermedia by SDS-PAGE followed by blotting to PVDF membrane and sequencing. A database search showed a high level of identity between each toxin and a fragment of theL. reclusa (North American spider) toxin. A multiple sequence alignment of theLoxosceles toxins showed many common identical residues in their N-terminal sequences. Identities ranged from 50.0% (L. gaucho andL. reclusa) to 61.1% (L. intermedia andL. reclusa). The purified toxins were also submitted to capillary electrophoresis peptide mapping afterin situ partial hydrolysis of the blotted samples. The results obtained suggest thatL. intermedia protein is more similar toL. laeta toxin thanL. gaucho toxin and revealed a smaller homology betweenL. intermedia andL gaucho. Altogether these findings suggest that the toxins responsible for most important activities of venoms ofLoxosceles species have a molecular mass of 32–35 kDa and are probably homologous proteins.     

Chemogenomic Study of Carboplatin in Saccharomyces cerevisiae: Inhibition of the NEDDylation Process Overcomes Cellular Resistance Mediated by HuR and Cullin Proteins

The use of carboplatin in cancer chemotherapy is limited by the emergence of drug resistance. To understand the molecular basis for this resistance, a chemogenomic screen was performed in 53 yeast mutants that had previously presented strong sensitivity to this widely used anticancer agent. Thirty-four mutants were responsive to carboplatin, and from these, 21 genes were selected for further studies because they have human homologues. Sixty percent of these yeast genes possessed human homologues which encoded proteins that interact with cullin scaffolds of ubiquitin ligases, or whose mRNA are under the regulation of Human antigen R (HuR) protein. Both HuR and cullin proteins are regulated through NEDDylation post-translational modification, and so our results indicate that inhibition of this process should sensitise resistant tumour cells to carboplatin. We showed that treatment of a tumour cell line with MLN4924, a NEDDylation inhibitor, overcame the resistance to carboplatin. Our data suggest that inhibition of NEDDylation may be a useful strategy to resensitise tumour cells in patients that have acquired carboplatin resistance.