Identification of the phospholipid lysobisphosphatidic acid in the protozoan Entamoeba histolytica: An active molecule in endocytosis

Phospholipids are essential for vesicle fusion and fission and both are fundamental events for Entamoeba histolytica phagocytosis. Our aim was to identify the lysobisphosphatidic acid (LBPA) in trophozoites and investigate its cellular fate during endocytosis. LBPA was detected by TLC in a 0.5 R_f spot of total lipids, which co-migrated with the LBPA standard. The 6C4 antibody, against LBPA recognized phospholipids extracted from this spot. Reverse phase LC-ESI-MS and MS/MS mass spectrometry revealed six LBPA species of m/z 772.58–802.68. LBPA was associated to pinosomes and phagosomes. Intriguingly, during pinocytosis, whole cell fluorescence quantification showed that LBPA dropped 84% after 15 min incubation with FITC-Dextran, and after 60 min, it increased at levels close to steady state conditions. Similarly, during erythrophagocytosis, after 15 min, LBPA also dropped in 36% and increased after 60 and 90 min. EhRab7A protein appeared in some vesicles with LBPA in steady state conditions, but after phagocytosis co-localization of both molecules increased and in late phases of erythrophagocytosis they were found in huge phagosomes or multivesicular bodies with many intraluminal vacuoles, and surrounding ingested erythrocytes and phagosomes. The 6C4 and anti-EhADH (EhADH is an ALIX family protein) antibodies and Lysotracker merged in about 50% of the vesicles in steady state conditions and throughout phagocytosis. LBPA and EhADH were also inside huge phagosomes. These results demonstrated that E. histolytica LBPA is associated to pinosomes and phagosomes during endocytosis and suggested differences of LBPA requirements during pinocytosis and phagocytosis.     

Development and validation of a weight-bearing finite element model for total knee replacement

Total knee arthroplasty (TKA) is a successful procedure for osteoarthritis. However, some patients (19%) do have pain after surgery. A finite element model was developed based on boundary conditions of a knee rig. A 3D-model of an anatomical full leg was generated from magnetic resonance image data and a total knee prosthesis was implanted without patella resurfacing. In the finite element model, a restarting procedure was programmed in order to hold the ground reaction force constant with an adapted quadriceps muscle force during a squat from 20° to 105° of flexion. Knee rig experimental data were used to validate the numerical model in the patellofemoral and femorotibial joint. Furthermore, sensitivity analyses of Young’s modulus of the patella cartilage, posterior cruciate ligament (PCL) stiffness, and patella tendon origin were performed. Pearson’s correlations for retropatellar contact area, pressure, patella flexion, and femorotibial ap-movement were near to 1. Lowest root mean square error for retropatellar pressure, patella flexion, and femorotibial ap-movement were found for the baseline model setup with Young’s modulus of 5 MPa for patella cartilage, a downscaled PCL stiffness of 25% compared to the literature given value and an anatomical origin of the patella tendon. The results of the conducted finite element model are comparable with the experimental results. Therefore, the finite element model developed in this study can be used for further clinical investigations and will help to better understand the clinical aspects after TKA with an unresurfaced patella.     

A molecular link between malaria and Epstein-Barr virus reactivation

Although malaria and Epstein-Barr (EBV) infection are recognized cofactors in the genesis of endemic Burkitt lymphoma (BL), their relative contribution is not understood. BL, the most common paediatric cancer in equatorial Africa, is a high-grade B cell lymphoma characterized by c-myc translocation. EBV is a ubiquitous B lymphotropic virus that persists in a latent state after primary infection, and in Africa, most children have sero-converted by 3 y of age. Malaria infection profoundly affects the B cell compartment, inducing polyclonal activation and hyper-gammaglobulinemia. We recently identified the cystein-rich inter-domain region 1alpha (CIDR1alpha) of the Plasmodium falciparum membrane protein 1 as a polyclonal B cell activator that preferentially activates the memory compartment, where EBV is known to persist. Here, we have addressed the mechanisms of interaction between CIDR1alpha and EBV in the context of B cells. We show that CIDR1alpha binds to the EBV-positive B cell line Akata and increases the number of cells switching to the viral lytic cycle as measured by green fluorescent protein (GFP) expression driven by a lytic promoter. The virus production in CIDR1alpha-exposed cultures was directly proportional to the number of GFP-positive Akata cells (lytic EBV) and to the increased expression of the EBV lytic promoter BZLF1. Furthermore, CIDR1alpha stimulated the production of EBV in peripheral blood mononuclear cells derived from healthy donors and children with BL. Our results suggest that P. falciparum antigens such as CIDR1alpha can directly induce EBV reactivation during malaria infection that may increase the risk of BL development for children living in malaria-endemic areas. To our knowledge, this is the first report to show that a microbial protein can drive a latently infected B cell into EBV replication.     

Enhanced expression of the Epithelial Sodium Channel in neutrophils from hypertensive patients

Hypertension (HTN), i.e. abnormally high blood pressure, is a major risk factor for heart attack, stroke, and kidney failure. The Epithelial Sodium Channel (ENaC), one of the main transporters regulates blood pressure by tightly controlling the sodium reabsorption along the nephron. Recently, we have shown an α-ENaC overexpression in platelets from hypertensive patients compared to platelets from normotensive subjects, suggesting it makes a contribution to the activation state of platelets and the physiopathology of hypertension. However, the involvement of the α-ENaC localized in neutrophils to this disease remains unknown. Neutrophils are the first leukocytes to be recruited to an inflammatory site and are equipped with a strong ability to eliminate intra- or extracellular pathogens using reactive oxygen species or antibacterial proteins contained in their granules.Using the Western blotting (Wb), flow cytometry, and qRT-PCR approaches; we determined α-ENaC neutrophil overexpression at the protein and messenger RNA (mRNA) levels. By confocal and cytometry analysis, we determined the α-ENaC distribution and the heterogeneity of HTN neutrophils population, respectively. Immunoprecipitation and Wb assays demonstrated the presence of both α-ENaC and caveolin-1 phosphorylated forms, compared with neutrophils from healthy individuals. Although neutrophils from hypertensive subjects circulating in an activated state were exhibiting important oxidative stress and modifications registered by confocal, atomic force, and scanning electron microscope, they conserved their defense capabilities. The features described above for neutrophils from hypertensive patients could be attributed to α-ENaC overexpression, as its drug inhibition diminished their activation state modulating the actin cytoskeleton reorganization triggered during the activation process.     

Unusual amino acids VI. Substituted arylamino acids by asymmetric hydrogenation of N-Cbz and N-Boc protected dehydroamino acid derivatives

Substituted N-Cbz and N-Boc protected arylamino acrylic acids and esters have been prepared and used in asymmetric hydrogenations catalyzed by PROPRAPHOSRh. Stereoselectivities > 90% ee could be achieved, the rate of which is dependent on the position of the substituent in the aromatic ring. The N-Boc derivatives provide advantages compared with the N-Cbz analogues. The amino acid derivatives were fully characterized by ¹⁹F, ¹³C, and ¹H NMR spectroscopy. © 1996 Wiley-Liss, Inc.     

Efectos del uso del 17 β-estradiol y la genisteína en la enfermedad de Alzheimer en mujeres con menopausia

The use of 17 β-estradiol and genistein in women with menopause helps in the reduction of vasomotor symptoms and cognitive improvement. There is evidence on the use of certain flavonoids such as genistein, which has a potentially neuroprotective role in neurodegenerative diseases such as Alzheimer's. Scientific evidence on the effects of phytoestrogens and genistein during menopause and their effect on cognition are scarce, however, in the present review it was found that the intervention with 17 β-estradiol has positive effects on cognition in women with Alzheimer's disease. In addition, the use of genistein, daidzein or any supplement based on isoflavones may influence vasomotor symptoms. 17 β-estradiol supplements in women in early menopause and with some degree of cognitive impairment may have beneficial effects.     

Microbiological Processes in a High-Temperature Oil Field

Thermophilic sulfate-reducing bacteria (SRB) oxidizing lactate, butyrate, and C₁₂–C₁₆ n-alkanes of oil at a temperature of 90°C were isolated from samples of water and oil originating from oil reservoirs of the White Tiger high-temperature oil field (Vietnam). At the same time, no thermophiles were detected in the injected seawater, which contained mesophilic microorganisms and was the site of low-temperature processes of sulfate reduction and methanogenesis. Thermophilic SRB were also found in samples of liquid taken from various engineering reservoirs used for oil storage, treatment, and transportation. These samples also contained mesophilic SRB, methanogens, aerobic oil-oxidizing bacteria, and heterotrophs. Rates of bacterial production of hydrogen sulfide varied from 0.11 to 2069.63 at 30°C and from 1.18 to 173.86 at 70°C g S/(l day); and those of methane production, varied from 58.4 to 100 629.8 nl CH₄/(l day) (at 30°C). The sulfur isotopic compositions of sulfates contained in reservoir waters and of hydrogen sulfide of the accompanying gas indicate that bacterial sulfate reduction might be effective in the depth of the oil field.