3,195 research outputs found
Adenocarcinoma do pâncreas localmente avançado e metastizado com resposta completa a quimioterapia
Os autores apresentam o caso clĂnico de doente do sexo
feminino, 54 anos, raça branca, que recorreu ao médico
assistente por dor abdominal associada a manifestações
constitucionais. A ecografia revelou massa pancreática e
formações nodulares hepáticas compatĂveis com lesões
secundárias, resultado posteriormente corroborado por
tomografia computorizada, que acrescentou critérios de
irressecabilidade, nomeadamente invasĂŁo dos vasos mesen-
téricos e do duodeno. A biopsia ecoguiada obteve material
cujo estudo anatomopatolĂłgico revelou tratar-se de adeno-
carcinoma do pâncreas. Iniciou quimioterapia, verifican-
do-se melhoria clĂnica progressiva. A reavaliação imagio-
lĂłgica, apĂłs 7 ciclos de tratamento, nĂŁo detectou a lesĂŁo
primitiva nem as lesões secundárias, sugerindo resposta
completa. Foi mantido esquema regular de quimioterapia,
persistindo a remissão 8 meses após a documentação da
resposta completa
A two-step transport pathway allows the mother cell to nurture the developing spore in Bacillus subtilis
© 2017 RamĂrez-Guadiana et al. One of the hallmarks of bacterial endospore formation is the accumulation of high concentrations of pyridine-2,6-dicarboxylic acid (dipicolinic acid or DPA) in the developing spore. This small molecule comprises 5–15% of the dry weight of dormant spores and plays a central role in resistance to both wet heat and desiccation. DPA is synthesized in the mother cell at a late stage in sporulation and must be translocated across two membranes (the inner and outer forespore membranes) that separate the mother cell and forespore. The enzymes that synthesize DPA and the proteins required to translocate it across the inner forespore membrane were identified over two decades ago but the factors that transport DPA across the outer forespore membrane have remained mysterious. Here, we report that SpoVV (formerly YlbJ) is the missing DPA transporter. SpoVV is produced in the mother cell during the morphological process of engulfment and specifically localizes in the outer forespore membrane. Sporulating cells lacking SpoVV produce spores with low levels of DPA and cells engineered to express SpoVV and the DPA synthase during vegetative growth accumulate high levels of DPA in the culture medium. SpoVV resembles concentrative nucleoside transporters and mutagenesis of residues predicted to form the substrate-binding pocket supports the idea that SpoVV has a similar structure and could therefore function similarly. These findings provide a simple two-step transport mechanism by which the mother cell nurtures the developing spore. DPA produced in the mother cell is first translocated into the intermembrane space by SpoVV and is then imported into the forespore by the SpoVA complex. This pathway is likely to be broadly conserved as DPA synthase, SpoVV, and SpoVA proteins can be found in virtually all endospore forming bacteria
An alternative synthetic access to cis-4a-Methyloctahydrophenanthrene, a biomarker of Sergipe-Alagoas Basin petroleum in Brazil
cis-4a-Methyloctahydrophenanthrene (1) was prepared in 8 steps (23% overall yield) from 2-bromophenyl)acetic acid (3) and cyclohexane-1,3-dione (6). A highly cis-diastereoselective Michael-type Heck coupling served as the key step in the assembly of the tricyclic skeleton. This compound 1 was used as gas chromatography standard which allowed the unequivocal identification of a minor biomarker present in Carmopolis oil from the Sergipe-Alagoas Basin in Brazil.13566466
On the Stability and Structural Dynamics of Metal Nanowires
This article presents a brief review of the nanoscale free-electron model,
which provides a continuum description of metal nanostructures. It is argued
that surface and quantum-size effects are the two dominant factors in the
energetics of metal nanowires, and that much of the phenomenology of nanowire
stability and structural dynamics can be understood based on the interplay of
these two competing factors. A linear stability analysis reveals that metal
nanocylinders with certain magic conductance values G=1, 3, 6, 12, 17, 23, 34,
42, 51, 67, 78, 96, ... times the conductance quantum are exceptionally stable.
A nonlinear dynamical simulation of nanowire structural evolution reveals a
universal equilibrium shape consisting of a magic cylinder suspended between
unduloidal contacts. The lifetimes of these metastable structures are also
computed.Comment: 8 pages, 6 figure
Intramuscular EMG-driven musculoskeletal modelling: towards implanted muscle interfacing in spinal cord injury patients
OBJECTIVE: Surface EMG-driven modelling has been proposed as a means to control assistive devices by estimating joint torques. Implanted EMG sensors have several advantages over wearable sensors but provide a more localized information on muscle activity, which may impact torque estimates. Here, we tested and compared the use of surface and intramuscular EMG measurements for the estimation of required assistive joint torques using EMG driven modelling. METHODS: Four healthy subjects and three incomplete spinal cord injury (SCI) patients performed walking trials at varying speeds. Motion capture marker trajectories, surface and intramuscular EMG, and ground reaction forces were measured concurrently. Subject-specific musculoskeletal models were developed for all subjects, and inverse dynamics analysis was performed for all individual trials. EMG-driven modelling based joint torque estimates were obtained from surface and intramuscular EMG. RESULTS: The correlation between the experimental and predicted joint torques was similar when using intramuscular or surface EMG as input to the EMG-driven modelling estimator in both healthy individuals and patients. CONCLUSION: We have provided the first comparison of non-invasive and implanted EMG sensors as input signals for torque estimates in healthy individuals and SCI patients. SIGNIFICANCE: Implanted EMG sensors have the potential to be used as a reliable input for assistive exoskeleton joint torque actuation
Enteric Neurospheres Are Not Specific to Neural Crest Cultures: Implications for Neural Stem Cell Therapies
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited
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