Self-Assembly of Phosphocholine Derivatives Using the ELBA Coarse-Grained Model: Micelles, Bicelles, and Reverse Micelles.

The ELBA coarse-grained force field was originally developed for lipids, and its water model is described as a single-site Lennard-Jones particle with electrostatics modeled by an embedded point-dipole, while other molecules in this force field have a three (or four)-to-one mapping scheme. Here, ELBA was applied to investigate the self-assembly processes of dodecyl-phosphocholine (DPC) micelle, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/1,2-dihexaoyl-sn-glycero-3-phosphocholine (DPPC/DHPC) bicelles, and DPPC/cyclohexane/water reverse micelles through coarse-grained molecular dynamics (MD) simulations. New parameters were obtained using a simplex algorithm-based calibration procedure to determine the Lennard-Jones parameters for cyclohexane, dodecane, and cyclohexane-dodecane cross-interactions. Density, self-diffusion coefficient, surface tension, and mixture excess volume were found to be in fair agreement with experimental data. These new parameters were used in the simulations, and the obtained structures were analyzed for shape, size, volume, and surface area. Except for the shape of DPC micelles, all other properties match well with available experimental data and all-atom simulations. Remarkably, in agreement with experiments the rodlike shape of the DPPC reverse micelle is well described by ELBA, while all-atom data in the literature predicts a disclike shape. To further check the consistency of the force field in reproducing the correct shapes of reverse micelles, additional simulations were performed doubling the system size. Two distinct reverse micelles were obtained both presenting the rodlike shape and correct aggregation number.

Methylene Blue Location in (Hydroperoxized) Cardiolipin Monolayer: Implication in Membrane Photodegradation.

We present molecular dynamics simulations of cardiolipin (CL) and CL monohydroperoxized derivative (CLOOH) monolayers to investigate the initial steps of phospholipid oxidation induced by methylene blue (MB) photoexcitation under continuous illumination. We considered different MB atomic charge distributions to simulate the MB electronic distribution in the singlet ground and triplet excited states. Simulation results allied to experimental data revealed that initial CL photooxidation probably occurs via a type II mechanism, to produce lipid hydroperoxide by singlet oxygen attack to the alkyl chain unsaturations. The resulting hydroperoxide group prefers to reside near the aqueous interface, to increase the membrane surface area and to decrease lipid packing. Interestingly, MB orientation changes from nearly parallel to the water-monolayer interface in the ground state to normal to the interface in its triplet excited state. The latter orientation favors oxidative chain reaction continuity via a type I mechanism, during which the hydrogen atom must be transferred from the hydroperoxide group to triplet MB. Taken together, the present results can be extrapolated to improve our understanding of how oxidation progresses in lipidic biomembrane, which will lead to the formation of oxidized species with shortened chains and will cause severe photodamage to self-organized systems.

An overview of molecular dynamics simulations of oxidized lipid systems, with a comparison of ELBA and MARTINI force fields for coarse grained lipid simulations.

Biological membranes and model lipid systems containing high amounts of unsaturated lipids and sterols are subject to chemical and/or photo-induced lipid oxidation, which leads to the creation of exotic oxidized lipid products (OxPLs). OxPLs are known to have significant physiological impact in cellular systems and also affect physical properties of both biological and model lipid bilayers. In this paper we (i) provide a perspective on the existing literature on simulations of lipid bilayer systems containing oxidized lipid species as well as the main related experimental results, (ii) describe our new data of all-atom and coarse-grained simulations of hydroperoxidized lipid monolayer and bilayer systems and (iii) provide a comparison of the MARTINI and ELBA coarse grained force fields for lipid bilayer systems. We show that the better electrostatic treatment of interactions in ELBA is able to resolve previous conflicts between experiments and simulations. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.

Bacterial Leaf Spot of Radicchio (Cichorium intybus) is caused by Xanthomonas hortorum.

Radicchio (Cichorium intybus) is ranked 22 among crops in Monterey County, California, with a farm gate value of $19,531,000 (3). Beginning in 2002, a leaf spot disease of radicchio was observed in Monterey County. The disease began as small lesions and in some cases coalesced into larger, irregular spots. Lesions were maroon to dark brown; in some cases, the margins of brown lesions became dark maroon with aging. Each leaf spot was observable from both adaxial and abaxial leaf surfaces. Symptoms primarily occurred on the outer foliage of the heads, though on occasion the head cap leaf could develop lesions. Disease incidence in the first year resulted in up to 10% unharvested radicchio because of cap leaf infections or reduced head size if outer wrapper leaves were all removed; outbreaks in subsequent seasons were more limited. Bacteria forming yellow mucoid colonies were isolated from surface disinfested symptomatic tissue that was macerated and streaked onto sucrose peptone agar medium. Bacteria were gram negative, did not fluoresce on King's Medium B, and used esculin as a carbon source but used none of the other 48 carbon sources tested using the API 50 CH test strip. Nine isolates from symptomatic radicchio had the same DNA fragment banding pattern generated by repetitive extragenic palindromic sequence polymerase chain reactions (rep-PCR) using the BOXA1R primer. Amplicons of rpoD, dnaK, fyuA, and gyrB for multilocus sequence typing (MLST) were generated using a modification of the scheme developed by Young et al. (4) and sequenced by a commercial laboratory. Concatenated sequences of the four genes from the radicchio isolates were compared to the sequences available in the Plant Associated and Environmental Microbes Database (1). The genetic distance between the nine isolates from radicchio and pathotypes of Xanthomonas hortorum were 0.03 or less and MLST analysis indicated that radicchio isolates were members of the species X. hortorum (2). To complete Koch's postulates, freshly grown cultures were suspended in phosphate buffer and adjusted to approximately 5 × 108 CFU/ml. The inoculum was sprayed onto the undersides of leaves of 40-day-old radicchio plants (C. intybus cv. Leonardo). Plants were incubated at 100% humidity for 48 h and then moved to a greenhouse. Plants sprayed with buffer served as negative controls. For each of the two experiments conducted, there were three and six single-plant replicates per treatment. The buffer treated plants did not develop symptoms but the plants treated with isolates from radicchio developed leaf spots similar to those observed in the field with symptoms beginning to be visible after 5 days. The bacteria isolated from symptomatic tissue on inoculated plants were identical to the original strains when compared with rep-PCR, thus completing Koch's postulates. Results from the two experiments were similar. To our knowledge, this is the first report of X. hortorum causing a leaf spot disease on radicchio. The disease continues to occur sporadically on radicchio grown in coastal California. References: (1) Almeida et al. Phytopathology 100:208, 2010. (2) Bull et al. Phytopathology 101:847, 2011. (3) Lauritzen, Monterey County Crop Report, 2010; (4) Young et al. Syst. Appl. Microbiol. 31:366, 2008.

The environmental dimensions of the HIV/AIDS pandemic: a call for scholarship and evidence-based intervention.

The HIV/AIDS pandemic has had dramatic influence on the demographic dynamics of many of the world's less economically developed regions. Today, an estimated 33 million individuals are living with HIV, and recent data suggest that, every day, over 6800 persons become HIV-infected and over 5700 persons die from AIDS (UNAIDS 2006). The age profile of HIV infection is well known, with new cases impacting primarily prime-age adults. Sub-Saharan Africa remains the world's most affected region with recent population-based surveys suggesting that adult prevalence rates (age 15-49) reaches as high as 25% in Botswana and over 23% in Lesotho (UNAIDS 2006). Still, HIV/AIDS also impacts children, with over 2 million HIV+ individuals under age 15 in sub-Saharan Africa; And the disease profile now includes many individuals over age 50 due to the positive impact on life expectancy of recent treatment advances (UNAIDS 2006).Of course, HIV/AIDS' impacts at the individual and household levels are difficult to discern from aggregate data although ethnographic research provides insights into nuanced household survival strategies (e.g., Evans 2005; Schatz and Ogunmefun 2007). Such work reveals household efforts to maintain a sense of "normality" in response to the impacts of HIV/AIDS, otherwise known as "the disease" (Bohman et al. 2007).

Cocaine addicts and their families. An empirical study of the processes of identification.

The processes of identification between adolescent cocaine addicts and their parents were studied in 402 subjects, in total 134 familial triads (father-mother-son), subdivided into two groups of 67 triads, one of these groups having as the child an adolescent of masculine sex dependent on cocaine and the other, equal in number, being a control group, duly matched for age and socio-economic status. The instrument employed was the Rorschach test (1922), limited to the application of the Lerner Defense Scale (LDS; Lerner & Lerner, 1980). The findings in the affected triads showed up as consistent statistically for the presence of intense processes of pathological identification, especially between father and son, a sign of the importance of the presence of disturbances of paternal function in the development of this addiction. The utilisation of very regressive defence mechanisms, above all of projective identification, was the predominant mode of procedure in triads with a dependent child. In comparisons between the fathers the odds ratio (OR) for projective identification was 8.66 to 1, which points to the association between cocaine addiction and the primitive mental functioning of the fathers. With empirical methodology these findings serve to corroborate the psychoanalytical conclusions based on studies of single case studies, testifying that the dysfunctions of identificatory phenomena in familial functioning are predominant in the mental organisation of cocaine addicts.

[Pattern of recovery of victims of cranio-encephalic injuries at 6 months and 1 year]. / Padrão de recuperação das vítimas de trauma crânio-encefálico aos 6 meses e 1 ano.

A prospective and longitudinal study of head injury victims was conducted to identify the pattern of recovery 6 months and 1 year post-trauma. Patients with variety levels of injury and age between 12 and 60 years were observed. Functional limitation was analyzed using the eight-point Glasgow Outcome Scale (GOS). The majority of these victims had the following characteristics: age were < or = 35 years (68.6%); ISS > or = (51.9%) and Glasgow Coma Scale > or = 13 (72.2%) when they were examined by team of neurosurgeons at first time. Complete recovery or GOS 0 was achieved in 21.3% of the victims about 6 months after onset of injury and 38.6%, at the 1 year mark, Overall, the majority of victims made good recovery after 6 months post-injury, that is, GOS 0 or 1, and had returned to productivity in that period. The majority (65.0%) of victims reached their highest GOS outcome category by 6 months, although significant improvement was shown between 6 months and 1 year post-trauma. Similarly, return to productivity was higher 1 year after injury later than at 6 months. Findings indicated that GOS-GCS correlation was negative, and in some conditions GOS was correlated or associated with ISS and age. Return to work was not related to education level or job type.

The growth of the embryonic rat myocardium (Carnegie stages 13 to 23).

The relative growth of the myocardium was studied in the postsomite embryos (Carnegie stages 13 to 23) of 54 rats (Rattus norvegicus). Cavalieri's principle was applied to determine the myocardial volume of each rat heart. The calculated volume was related to the corresponding body weight and crown-rump length using a bivariate allometric equation. The resulting scattergram proved to be discontinuous: the rate of myocardial growth in the postsomite embryo was represented by two distinct phases. The first, from stages 13 to 20, was allometrically-negative; the second, from stages 21 to 23, allometrically-positive. This difference in myocardial growth rate might have been due in part to the functional increase of circulatory flow in the peripheral vascular bed in response to the demand for increased cardiac output that occurs at the conclusion of the embryonic period.