Micellar electrokinetic chromatography with laser induced fluorescence detection shows increase of putrescine in erythrocytes of Parkinson's disease patients.

A highly sensitive method was developed to measure putrescine by micellar electrokinetic chromatography with laser induced fluorescence detection with excellent linearity in the 1 nM to 3 µM range. The technique was tested on a drop of blood from Parkinson's disease patients obtained by finger prick. The results showed a statistically significant increase of putrescine in the erythrocytes compared to controls and a non-significant increase in plasma. This high level of putrescine does not constitute by itself proof that putrescine and polyamines are directly related to Parkinson's disease. However, the present results and several others addressed in the discussion suggest that these compounds might be causally involved in the pathophysiology of Parkinson's disease. In addition, the analytical method reported here may help to find new biomarkers for many diseases including Parkinson's disease.

Characterization of the cytotoxic effects of the combination of cisplatin and flavanol (-)-epicatechin on human lung cancer cell line A549. An isobolographic approach.

BACKGROUND: Among malignancies, lung cancer is a leading cause of death. Platinum-based therapeutic compounds used to treat lung cancer have not been able to increase the survival of patients and such compounds have a high incidence of adverse and toxic effects. It has been proposed that flavonoids such as catechins may significantly reduce the risk of developing cancer, alongside with other health benefits. The aim of this work was to determine the effect of (-)-epicatechin, the main flavanol found in cocoa, on the proliferation of the lung non-small cell adenocarcinoma cancer cell line A549, and to determine its effects when added simultaneously with cisplatin. MATERIALS AND METHODS: Concentration-response curves for cisplatin and epicatechin were obtained, inhibitory concentrations calculated and an isobolographic analysis was then performed. RESULTS: We found that epicatechin has a concentration-dependent inhibitory effect on proliferation of tumor cells and the isobolographic analysis reveals that the effect of its combination with cisplatin is synergistic. It was also observed that epicatechin promotes cell death by apoptosis. CONCLUSIONS: Epicatechin might be considered for future studies to explore its possible use as coadjuvant in cisplatin-based treatments.

Dysregulation of mitochondrial function and biogenesis modulators in adipose tissue of obese children.

BACKGROUND/OBJECTIVES: We aimed to evaluate mitochondrial biogenesis (MB), structure, metabolism and dysfunction in abdominal adipose tissue from male pediatric patients with obesity. SUBJECTS/METHODS: Samples were collected from five children with obesity (percentile ⩾95) and five eutrophic boys (percentile ⩾5/⩽85) (8-12 years old) following parental informed consent. We analyzed the expression of key genes involved in MB (sirtuin-1 (SIRT1), peroxisome proliferator-activated receptor-γ (PPARγ), PPARγ coactivator-1α (PGC1α), nuclear respiratory factors 1 and 2 (NRF1, NRF2) and mitochondrial transcription factor A (TFAM) and surrogates for mitochondrial function/structure/metabolism (porin, TOMM20, complex I and V, UCP1, UCP2, SIRT3, SOD2) by western blot. Citrate synthase (CS), complex I (CI) activity, adenosine triphosphate (ATP) levels, mitochondrial DNA (mtDNA) content and oxidative stress end points were also determined. RESULTS: Most MB proteins were significantly decreased in samples from children with obesity except complex I, V and superoxide dismutase-2 (SOD2). Similarly, CS and CI activity showed a significant reduction, as well as ATP levels and mtDNA content. PPARγ, PGC1α, complex I and V and SOD2 were hyperacetylated compared with lean samples. Concurrently, in samples from children with obesity, we found decreased SOD2 activity and redox state imbalance highlighted by decreased reduced glutathione/oxidized glutathione (GSH/GSSG) ratio and significant increases in protein carbonylation. CONCLUSIONS: Adipose tissue from children with obesity demonstrates a dysregulation of key modulators of MB and organelle structure, and displays hyperacetylation of key proteins and altered expression of upstream regulators of cell metabolism.

Non-target adjacent stimuli classification improves performance of classical ERP-based brain computer interface.

OBJECTIVE: The classical ERP-based speller, or P300 Speller, is one of the most commonly used paradigms in the field of Brain Computer Interfaces (BCI). Several alterations to the visual stimuli presentation system have been developed to avoid unfavorable effects elicited by adjacent stimuli. However, there has been little, if any, regard to useful information contained in responses to adjacent stimuli about spatial location of target symbols. This paper aims to demonstrate that combining the classification of non-target adjacent stimuli with standard classification (target versus non-target) significantly improves classical ERP-based speller efficiency. APPROACH: Four SWLDA classifiers were trained and combined with the standard classifier: the lower row, upper row, right column and left column classifiers. This new feature extraction procedure and the classification method were carried out on three open databases: the UAM P300 database (Universidad Autonoma Metropolitana, Mexico), BCI competition II (dataset IIb) and BCI competition III (dataset II). MAIN RESULTS: The inclusion of the classification of non-target adjacent stimuli improves target classification in the classical row/column paradigm. A gain in mean single trial classification of 9.6% and an overall improvement of 25% in simulated spelling speed was achieved. SIGNIFICANCE: We have provided further evidence that the ERPs produced by adjacent stimuli present discriminable features, which could provide additional information about the spatial location of intended symbols. This work promotes the searching of information on the peripheral stimulation responses to improve the performance of emerging visual ERP-based spellers.

Atomic monolayer deposition on the surface of nanotube mechanical resonators.

We study monolayers of noble gas atoms (Xe, Kr, Ar, and Ne) deposited on individual ultraclean suspended nanotubes. For this, we record the resonance frequency of the mechanical motion of the nanotube, since it provides a direct measure of the coverage. The latter is the number of adsorbed atoms divided by the number of the carbon atoms of the suspended nanotube. Monolayers form when the temperature is lowered in a constant pressure of noble gas atoms. The coverage of Xe monolayers remains constant at 1/6 over a large temperature range. This finding reveals that Xe monolayers are solid phases with a triangular atomic arrangement, and are commensurate with the underlying carbon nanotube. By comparing our measurements to theoretical calculations, we identify the phases of Ar and Ne monolayers as fluids, and we tentatively describe Kr monolayers as solid phases. These results underscore that mechanical resonators made from single nanotubes are excellent probes for surface science.

Spin-dependent electron scattering at graphene edges on Ni(111).

We investigate the scattering of surface electrons by the edges of graphene islands grown on Ni(111). By combining local tunneling spectroscopy and ab initio electronic structure calculations we find that the hybridization between graphene and Ni states results in strongly reflecting graphene edges. Quantum interference patterns formed around the islands reveal a spin-dependent scattering of the Shockley bands of Ni, which we attribute to their distinct coupling to bulk states. Moreover, we find a strong dependence of the scattering amplitude on the atomic structure of the edges, depending on the orbital character and energy of the surface states.

Undifferentiated (anaplastic) thyroid carcinoma and iodine intake in Salta, Argentina.

This study was conducted to investigate the natural history of undifferentiated thyroid carcinoma (UTC) in the iodine-deficient province of Salta, Argentina, in relation to salt iodization and health care standards. Five hundred ninety-three thyroid cancers diagnosed from 1958 to2012 were reviewed based mainly on the WHO classification and grouped into three periods, one before and two after iodine prophylaxis. The incidence of UTC was analyzed in relation to changing concentrations of potassium iodide (KI) in salt during the prophylaxis period (from 40 to 33.3 mg KI/kg salt), establishment of primary health care centers throughout the region, and use of fine needle aspiration (FNA) cytology. Twenty-nine UTCs were found in the whole series. The frequency of UTC decreased from 15.2 % (9/59 cases) in the first period to 2.6 % (10/381 cases) well after salt iodination (x (2) Fisher's test, p < 0.0002), and the incidence from 1.4/10(6)/year to 0.1/10(6)/year (Student's t test, p < 0.06), respectively. The decline of UTC after iodine prophylaxis occurred even after decreasing concentrations of KI in salt and timely coincided with the establishment of primary health care centers throughout the region and routine use of FNA. The lower rate of UTC after iodine prophylaxis in the province of Salta is mostly related to earlier detection of more differentiated thyroid tumors rather than higher salt iodization.

Yield and shape selection of graphene nanoislands grown on Ni(111).

The catalytic decomposition of hydrocarbons on transition-metal surfaces has attracted increasing interest as a method to prepare high quality graphene layers. Here, we study the optimal reaction path for the preparation of graphene nanoislands of selected shape using controlled decomposition of propene on Ni(111). Scanning tunneling microscopy performed at different stages of the reaction provides insight into the temperature and dose-dependent growth of graphene islands, which precedes the formation of monolayer graphene. The effect of postreaction annealing on the morphology of the islands is studied. By adjusting the initial propene dose, reaction temperature, and postannealing procedure, islands with a triangular or hexagonal shape can be selectively obtained.

A nanomechanical mass sensor with yoctogram resolution.

Nanomechanical resonators have been used to weigh cells, biomolecules and gas molecules, and to study basic phenomena in surface science, such as phase transitions and diffusion. These experiments all rely on the ability of nanomechanical mass sensors to resolve small masses. Here, we report mass sensing experiments with a resolution of 1.7 yg (1 yg = 10(-24) g), which corresponds to the mass of one proton. The resonator is a carbon nanotube of length ∼150 nm that vibrates at a frequency of almost 2 GHz. This unprecedented level of sensitivity allows us to detect adsorption events of naphthalene molecules (C(10)H(8)), and to measure the binding energy of a xenon atom on the nanotube surface. These ultrasensitive nanotube resonators could have applications in mass spectrometry, magnetometry and surface science.

Eficacia de la suplementación con L-arginina sobre la respuesta a la quimioterapia neoadyuvante en pacientes con cáncer de mama / Efficacy of L-arginine supplementation on response to neoadjuvant chemotherapy in patients with breast cancer

Introducción El cáncer de mama ocupa el primer lugar en mortalidad por neoplasias en la mujer en México. La quimioterapia neoadyuvante ha reportado una eficacia de alrededor 70%; sin embargo, aquellas pacientes que no responden adecuadamente deben someterse a métodos coadyuvantes que afectan su calidad de vida. El óxido nítrico, brevemente, en concentraciones altas es capaz de tener efectos citotóxicos y tumoricidas, favoreciendo una respuesta adecuada al tratamiento antineoplásico. La L-arginina es precursor del óxido nítrico, por lo que la suplementación puede influir en la síntesis y, por tanto, en su concentración.ObjetivosEvaluar la eficacia de la suplementación de L-arginina sobre la respuesta al tratamiento con quimioterapia neoadyuvante.Materiales y métodosEnsayo clínico de asignación aleatoria que administró un suplemento de 30g de L-arginina en cada ciclo de quimioterapia neoadyuvante. Se determinó la concentración de nitritos antes y después de ingerir el suplemento, así como el tamaño tumoral antes de iniciar el tratamiento y una vez concluido el mismo. Se realizó una prueba chi-cuadrado para evaluar la asociación entre la suplementación y una respuesta adecuada al tratamiento; los nitritos plasmáticos fueron evaluados mediante pruebas t-student.ResultadosSe evaluaron 45 pacientes. Veintiuno tuvieron una respuesta adecuada al tratamiento oncológico; sin embargo, no se encontró una asociación significativa entre la suplementación y dicha respuesta. La concentración de nitritos plasmáticos aumentó de manera significativa (p<0,05) en el grupo que recibió el suplemento con L-arginina.Conclusiones(..) (AU)

Background Breast cancer is the first cause of mortality from malignant neoplasms among women in Mexico. Neoadjuvant chemotherapy has a reported efficacy of approximately 70%; however, patients with inadequate response must undergo additional coadjuvant methods that negatively affect their quality of life. High concentrations of nitric oxide have shown cytotoxic and tumoricidal effects, thus favoring an adequate response to antineoplastic treatment. L-arginine is a nitric oxide precursor and therefore supplementation with this substance can augment nitric oxide synthesis and consequently its plasma concentration.ObjectivesTo evaluate the efficacy of L-arginine supplementation in response to neoadjuvant chemotherapeutic treatment.Materials and methodsWe conducted a randomized clinical trial in which 30g of L-arginine was administered in each neoadjuvant chemotherapy cycle. Plasma nitrite concentrations were determined before and after supplementation, as well as tumoral size before the start of antineoplastic treatment and after its completion. A chi-square test was performed to evaluate the association between the supplementation and adequate treatment response; plasma nitrites were evaluated by performing Student's T-tests.ResultsForty-five patients were assessed, of whom 21 had an adequate response to antineoplastic treatment. No statistically significant association was found between supplementation and adequate response. Nitrite concentrations in plasma were significantly increased (p<0.05) in patients receiving the supplement than in those who receiving placebo.Conclusions(..) (AU)

Orbital specific chirality and homochiral self-assembly of achiral molecules induced by charge transfer and spontaneous symmetry breaking.

We study the electronic mechanisms underlying the induction and propagation of chirality in achiral molecules deposited on surfaces. Combined scanning tunneling microscopy and ab initio electronic structure calculations of Cu-phthalocyanines adsorbed on Ag(100) reveal the formation of chiral molecular orbitals in structurally undistorted molecules. This effect shows that chirality can be manifest exclusively at the electronic level due to asymmetric charge transfer between molecules and substrate. Single molecule chirality correlates with attractive van der Waals interactions, leading to the propagation of chirality at the supramolecular level. Ostwald ripening provides an efficient pathway for complete symmetry breaking and self-assembly of homochiral supramolecular layers.

One hundred questions of importance to the conservation of global biological diversity.

We identified 100 scientific questions that, if answered, would have the greatest impact on conservation practice and policy. Representatives from 21 international organizations, regional sections and working groups of the Society for Conservation Biology, and 12 academics, from all continents except Antarctica, compiled 2291 questions of relevance to conservation of biological diversity worldwide. The questions were gathered from 761 individuals through workshops, email requests, and discussions. Voting by email to short-list questions, followed by a 2-day workshop, was used to derive the final list of 100 questions. Most of the final questions were derived through a process of modification and combination as the workshop progressed. The questions are divided into 12 sections: ecosystem functions and services, climate change, technological change, protected areas, ecosystem management and restoration, terrestrial ecosystems, marine ecosystems, freshwater ecosystems, species management, organizational systems and processes, societal context and change, and impacts of conservation interventions. We anticipate that these questions will help identify new directions for researchers and assist funders in directing funds.

Lesiones de lisfranc: reporte de dos casos / Lisfranc Injury: report of two cases

La Luxo-fracturas de Lisfranc tarsometatarsianas son poco frecuentes. 1 Se presenta caso 1: femenina de 34 años de edad, posterior a caída de aprox, 3 mts, con tumefacción y deformidad en medio pie Izquierdo. RX: luxación de tarsometatarsina homolateral. Caso 2, masculino de 24 años de edad, recibió traumatismo contuso en pie Izquierdo presentó tumefacción y deformidad en área tarsal media RX: luxo-fractura tarsometatarsina divergente, fractura de II-V metatarso; se realizó reducción abierta y fijación percutánea con alambres de Kirschner, sin complicaciones, coincidiendo el mismo mes de presentación, poco usual en la práctica médica, con evolución satisfactoria.

Insulating ground state of Sn/Si(111)-(square root 3 x square root 3)R30 degrees.

The Sn/Si(111)-(square root 3 x square root 3)R30 degrees surface was so far believed to be metallic according to the electron counting argument. We show, by using tunneling spectroscopy, scanning tunneling microscopy, photoemission, and photoelectron diffraction, that below 70 K this surface has a very low density of states at the Fermi level and is not appreciably distorted. The experimental results are compatible with the insulating Mott-Hubbard ground state predicted by LSDA+U calculations [G. Profeta and E. Tosatti, Phys. Rev. Lett. 98, 086401 (2007)].

Antibacterial properties of some plants used in Mexican traditional medicine for the treatment of gastrointestinal disorders.

Antibacterial properties of aqueous and methanolic extracts of 26 medicinal plants used in Mexico to treat gastrointestinal disorders were tested against eight different species of enteropathogens: two Escherichia coli species; two Shigella sonnei species; two Shigella flexneri species; and two Salmonella sp. species. The results showed that all crude extracts exhibited antibacterial activity, at least against one of the microorganisms tested, at concentrations of 8 mg/mL or lower. The extracts from Caesalpinia pulcherria, Chiranthodendron pentadactylon, Cocos nucifera, Geranium mexicanum (aerial parts and roots), Hippocratea excelsa, and Punica granatum possessed strong antibacterial activity against most of the pathogens tested. In general, methanolic extracts were more active than aqueous extracts. Their activity was higher than chloramphenicol but did not exceed that of trimethoprim. Shigella sonnei species showed the highest susceptibility to both extracts. This is the first evaluation of these plants against bacterial pathogen isolates, which cause diarrhea and dysentery in Mexican population.

Role of spin in quasiparticle interference.

Quasiparticle interference patterns measured by scanning tunneling microscopy can be used to study the local electronic structure of metal surfaces and high-temperature superconductors. Here, we show that even in nonmagnetic systems the spin of the quasiparticles can have a profound effect on the interference patterns. On Bi(110), where the surface state bands are not spin degenerate, the patterns are not related to the dispersion of the electronic states in a simple way. In fact, the features which are expected for the spin-independent situation are absent and the observed interference patterns can be interpreted only by taking spin-conserving scattering events into account.

Mesoscopic chiral reshaping of the Ag(110) surface induced by the organic molecule PVBA.

We report scanning tunneling microscopy observations on the restructuring of a Ag(110) surface induced by the molecule 4-[trans-2-(pyrid-4-yl-vinyl)]benzoic acid (PVBA). Our data reveal that the surface undergoes a mesoscopic step faceting following exposure to submonolayer coverages and thermal activation. A sawtooth arrangement evolves implying long-range mass transport of substrate atoms and forming a regular arrangement of kink sites. Its formation is associated with the molecules' functional headgroups forming carboxylates with [100] Ag microfacets at step edges, and eventually operating to reshape the surface morphology. Interestingly, the resulting microfacets act as chiral templates for the growth of supramolecular PVBA structures. Theoretical modeling based on ab initio results indicates that chiral recognition processes discriminating between the two enantiomers of adsorbed PVBA molecules occur in this process.

Microscopic mechanisms of self-compensation in Si delta-doped GaAs.

We combined systematic cross-sectional scanning tunneling microscopy and spectroscopy investigations with Hall measurements on single Si delta-doped layers, as well as Si delta-doped superlattices in GaAs. We found that Si self-compensation involves nucleation and growth of electrically neutral Si precipitates at the expense of the conventional donor Si phase.

Dentine structure and mineralization in hypocalcified amelogenesis imperfecta: a quantitative X-ray histochemical study.

OBJECTIVE: This study was undertaken in order to establish the structural and mineralization pattern of the response of dentine to alterations in enamel in hypocalcified amelogenesis imperfecta (AI). DESIGN: The images and data obtained with scanning electron microscopy and electron probe X-ray microanalysis in enamel and dentine specimens from control and affected teeth were compared in this study. PATIENTS AND METHODS: We compared 46 fragments of permanent teeth from patients with clinically diagnosed hypocalcified AI and 20 normal permanent teeth. All specimens were prepared for electron probe X-ray microanalysis. RESULTS: Dentine is characterized by thickening of the peritubular dentine and partial obliteration of the dentinal tubules that does not give rise to a compact sclerotic cast. In dentine, calcium levels were significantly higher in teeth with clinically hypocalcified AI in relation with control teeth (P < 0.001). CONCLUSIONS: Dentine is affected in hypocalcified AI increasing mineralization (narrower tubules and higher content of calcium) in response to enamel disorder.

Scanning electron microscopy and calcification in amelogenesis imperfecta in anterior and posterior human teeth.

Teeth fragments from members of a family clinically and genetically diagnosed as having amelogenesis imperfecta were studied by scanning electron microscopy and X-ray microprobe analysis to establish the morphological patterns and the quantitative concentration of calcium in the enamel of anterior (canine, incisor) and posterior (premolar and molar) teeth. The prism patterns in the enamel of teeth from both regions were parallel or irregularly decussate, with occasional filamentous prisms accompanied by small, irregularly rounded formations. Prismless enamel showed the R- and P-type patterns. Calcium levels in enamel of amelogenesis imperfecta and control teeth differed significantly between anterior and posterior teeth, indicating that the factors that influence normal mineralization in different regions of the dental arch are not altered in the process of amelogenesis imperfecta.