Did the prion protein become vulnerable to misfolding after an evolutionary divide and conquer event?

Despite high sequence identity among mammalian prion proteins (PrPs), mammals have varying rates of susceptibility to prion disease resulting in a so-called species barrier. The species barrier follows no clear pattern, with closely related species or similar sequences being no more likely to infect each other, and remains an unresolved enigma. Variation of the conformationally flexible regions may alter the thermodynamics of the conformational change, commonly referred to as the conformational conversion, which occurs in the pathogenic process of the mammalian prion protein. A conformational ensemble scenario is supported by the species barrier in prion disease and evidence that there are strains of pathogenic prion with different conformations within species. To study how conformational flexibility has evolved in the prion protein, an investigation was undertaken on the evolutionary dynamics of structurally disordered regions in the mammalian prion protein, non-mammalian prion protein that is not vulnerable to prion disease, and remote homologs Doppel and Shadoo. Structural disorder prediction analyzed in an evolutionary context revealed that the occurrence of increased or altered conformational flexibility in mammalian PrPs coincides with key events among PrP, Doppel, and Shadoo. Comparatively rapid evolutionary dynamics of conformational flexibility in the prion protein suggest that the species barrier is not a static phenomenon. A small number of amino acid substitutions can repopulate the conformational ensemble and have a disproportionately large effect on pathogenesis.     

Development of Novel Chitosan Microcapsules for Pulmonary Delivery of Dapsone: Characterization,Aerosol Performance,and In Vivo Toxicity Evaluation

Pneumocystis carinii pneumonia (PCP) is a major opportunistic infection that affects patients with human immunodeficiency virus. Although orally administered dapsone leads to high hepatic metabolism, decreasing the therapeutic index and causing severe side effects, this drug is an effective alternative for the treatment of PCP. In this context, microencapsulation for pulmonary administration can offer an alternative to increase the bioavailability of dapsone, reducing its adverse effects. The aim of this work was to develop novel dapsone-loaded chitosan microcapsules intended for deep-lung aerosolized drug delivery. The geometric particle size (D_4,3) was approximately 7 μm, the calculated aerodynamic diameter (d_aero) was approximately 4.5 μm, and the mass median aerodynamic diameter from an Andersen cascade impactor was 4.7 μm. The in vitro dissolution profile showed an efficient dapsone encapsulation, demonstrating the sustained release of the drug. The in vitro deposition (measured by the Andersen cascade impactor) showed an adequate distribution and a high fine particles fraction (FPF = 50%). Scanning electron microscopy of the pulmonary tissues demonstrated an adequate deposition of these particles in the deepest part of the lung. An in vivo toxicity experiment showed the low toxicity of the drug-loaded microcapsules, indicating a protective effect of the microencapsulation process when the particles are microencapsulated. In conclusion, the pulmonary administration of the novel dapsone-loaded microcapsules could be a promising alternative for PCP treatment.KEY WORDS: dapsone, dry powders inhalers, in vivo toxicity, microparticles, pulmonary drug delivery     

Classification of motor imagery tasks for BCI with multiresolution analysis and multiobjective feature selection

Background

Brain-computer interfacing (BCI) applications based on the classification of electroencephalographic (EEG) signals require solving high-dimensional pattern classification problems with such a relatively small number of training patterns that curse of dimensionality problems usually arise. Multiresolution analysis (MRA) has useful properties for signal analysis in both temporal and spectral analysis, and has been broadly used in the BCI field. However, MRA usually increases the dimensionality of the input data. Therefore, some approaches to feature selection or feature dimensionality reduction should be considered for improving the performance of the MRA based BCI.

Methods

This paper investigates feature selection in the MRA-based frameworks for BCI. Several wrapper approaches to evolutionary multiobjective feature selection are proposed with different structures of classifiers. They are evaluated by comparing with baseline methods using sparse representation of features or without feature selection.

Results and conclusion

The statistical analysis, by applying the Kolmogorov-Smirnoff and Kruskal–Wallis tests to the means of the Kappa values evaluated by using the test patterns in each approach, has demonstrated some advantages of the proposed approaches. In comparison with the baseline MRA approach used in previous studies, the proposed evolutionary multiobjective feature selection approaches provide similar or even better classification performances, with significant reduction in the number of features that need to be computed.

     

Paraptosis‐like cell death in Wistar rat granulosa cells

Follicular atresia, a common process present in all mammals, involves apoptotic and autophagic cell death. However, the participation of paraptosis, a type of caspase‐independent cell death, during follicular atresia is unknown. This study found swollen endoplasmic reticulum in the granulosa cells of adult Wistar rats. Calnexin was used as a marker of the endoplasmic reticulum at the ultrastructural and optical levels. The cells with swelling of the endoplasmic reticulum were negative to the TUNEL assay and active caspase‐3 immunodetection, indicating that this swelling is not part of any apoptotic or autophagic process. Additionally, immunodetection of the CHOP protein was used as a marker of endoplasmic reticulum stress, and this confirmed the presence of the paraptosis process. These data suggest that paraptosis‐like cell death is associated with the death of granulosa cells during follicular atresia in adult Wistar rats.     

Unusual records of deepwater teleosteans trawled off the western coast of Mexico

The first records of three midwater species for the Mexican ichthyofauna (Holtbyrnia laticauda, Brama dussumieri and Cubiceps baxteri), caught off the coast of Baja California, Mexico, in mid 2014, are reported. As far as is known, they are the first verified specimens, geo‐referenced and catalogued in a reference fish collection for the west coast of Mexico. The species' known distributions were extended northward in the eastern Pacific Ocean, ranging from 3495 to 8300 km.     

IFNγ Response to Mycobacterium tuberculosis,Risk of Infection and Disease in Household Contacts of Tuberculosis Patients in Colombia

Objectives

Household contacts (HHCs) of pulmonary tuberculosis patients are at high risk of Mycobacterium tuberculosis infection and early disease development. Identification of individuals at risk of tuberculosis disease is a desirable goal for tuberculosis control. Interferon-gamma release assays (IGRAs) using specific M. tuberculosis antigens provide an alternative to tuberculin skin testing (TST) for infection detection. Additionally, the levels of IFNγ produced in response to these antigens may have prognostic value. We estimated the prevalence of M. tuberculosis infection by IGRA and TST in HHCs and their source population (SP), and assessed whether IFNγ levels in HHCs correlate with tuberculosis development.

Methods

A cohort of 2060 HHCs was followed for 2–3 years after exposure to a tuberculosis case. Besides TST, IFNγ responses to mycobacterial antigens: CFP, CFP-10, HspX and Ag85A were assessed in 7-days whole blood cultures and compared to 766 individuals from the SP in Medellín, Colombia. Isoniazid prophylaxis was not offered to child contacts because Colombian tuberculosis regulations consider it only in children under 5 years, TST positive without BCG vaccination.

Results

Using TST 65.9% of HHCs and 42.7% subjects from the SP were positive (OR 2.60, p<0.0001). IFNγ response to CFP-10, a biomarker of M. tuberculosis infection, tested positive in 66.3% HHCs and 24.3% from the SP (OR = 6.07, p<0.0001). Tuberculosis incidence rate was 7.0/1000 person years. Children <5 years accounted for 21.6% of incident cases. No significant difference was found between positive and negative IFNγ responders to CFP-10 (HR 1.82 95% CI 0.79–4.20 p = 0.16). However, a significant trend for tuberculosis development amongst high HHC IFNγ producers was observed (trend Log rank p = 0.007).

Discussion

CFP-10-induced IFNγ production is useful to establish tuberculosis infection prevalence amongst HHC and identify those at highest risk of disease. The high tuberculosis incidence amongst children supports administration of chemoprohylaxis to child contacts regardless of BCG vaccination.     

The budding yeast proteins Spc24p and Spc25p interact with Ndc80p and Nuf2p at the kinetochore and are important for kinetochore clustering and checkpoint control

Here, we show that the budding yeast proteins Ndc80p, Nuf2p, Spc24p and Spc25p interact at the kinetochore. Consistently, Ndc80p, Nuf2p, Spc24p and Spc25p associate with centromere DNA in chromatin immunoprecipitation experiments, and SPC24 interacts genetically with MCM21 encoding a kinetochore component. Moreover, although conditional lethal spc24-2 and spc25-7 cells form a mitotic spindle, the kinetochores remain in the mother cell body and fail to segregate the chromosomes. Despite this defect in chromosome segregation, spc24-2 and spc25-7 cells do not arrest in metaphase in response to checkpoint control. Furthermore, spc24-2 cells showed a mitotic checkpoint defect when microtubules were depolymerized with nocodazole, indicating that Spc24p has a function in checkpoint control. Since Ndc80p, Nuf2p and Spc24p are conserved proteins, it is likely that similar complexes are part of the kinetochore in other organisms.     

Electrogenic behavior of the human red cell Ca2+ pump revealed by disulfonic stilbenes

Summary A systematic study was made of the action of 4-acetamido-4-isothiocyanostilbene-2,2-disulfonic acid (SITS) and 4,4-diisothiocyanostilbene-2,2-disulfonic acid (DIDS) on active Ca²⁺ transport of human erythrocytes. Pumping activity was estimated in inside-out vesicles (IOV's) by means of Ca²⁺-selective electrodes or use of tracer⁴⁵Ca²⁺. The stilbenes exhibited an approximately equal inhibitory potency and their action could be overcome by carbonyl cyanidep-trifluoromethoxyphenylhydrazone (FCCP) at low but not at high stilbene concentrations. In the absence of DIDS. Ca²⁺ transport was not affected upon addition of valinomycin, but it was appreciably reduced when vesicles were preincubated with low DIDS concentrations. Such an effect was strictly dependent on the external K⁺ concentration and it was abolished when valinomycin was added together with FCCP. Similar results were obtained using IOV's prepared from intact cells which had been previously exposed to the stilbene. The findings clearly demonstrate the presence in human red cells of a partially electrogenic Ca²⁺ pump, exchanging one Ca²⁺ ion for one proton.     

Domain formation by a Rhodococcus sp. biosurfactant trehalose lipid incorporated into phosphatidylcholine membranes

The study of the interaction of biosurfactants with biological membranes is of great interest in order to gain insight into the molecular mechanisms of their biological actions. In this work we report on the interaction of a bacterial trehalose lipid produced by Rhodococcus sp. with phosphatidylcholine membranes. Differential scanning calorimetry measurements show a good miscibility of the glycolipid in the gel state and immiscibility in the fluid state, suggesting domain formation. These domains have been visualized and characterized, for the first time, by scanning force microscopy. Incorporation of trehalose lipid into phosphatidylcholine membranes produces a small shift of the antisymmetric stretching band toward higher wavenumbers, as shown by FTIR, which indicates a weak increase in fluidity. The C=O stretching band shows that incorporation of trehalose lipid increases the proportion of the dehydrated component in mixtures with the three phospholipids at temperatures below and above the gel to liquid-crystalline phase transition. This dehydration effect is also supported by data on the phospholipid P=O stretching bands. Small-angle X-ray diffraction measurements show that in the samples containing trehalose lipid the interlamellar repeat distance is larger than in those of pure phospholipids. These results are discussed within the frame of trehalose lipid domain formation, trehalose lipid/phospholipid interactions and its relevance to membrane-related biological actions.     

A rational use of glucocorticoids in patients with early arthritis has a minimal impact on bone mass

Introduction  

Glucocorticoid (GC)-induced osteoporosis is a frequent complication in patients with rheumatoid arthritis. However, little information exists about the consequences of GC use in patients with early arthritis. Here we describe the variables underlying the use of GC in early arthritis, as well as its effect on bone-mineral density.