Computer-assisted image analysis of agonist-mediated microvascular constriction response in mouse cremaster muscle.

In this work, we implemented an automated method using a correlation coefficient to select a time interval with a minimum movement or rest interval, together with analysis of variance for measurement of blood vessel diameter in the cremaster muscle. Video images binarization using analysis of variance resulted in an enhanced and a clearly defined vessel wall. Histamine (1 mM) induced a marked reduction in vascular diameter (vasoconstriction) in the cremaster muscle from mice fed with standard (SD) and high fat diet (HFD). However, the effect of histamine was reduced in HFD mice compared to SD mice. Thus, the change in vascular diameter was 87.14% ± 7.44% and 52.63% ± 16.27% in SD and HFD mice, respectively. In conclusion, determination of a rest interval with minimal movement and the use of analysis of variance resulted useful to evaluate vascular diameter in small arteries. We suggest this method to streamline experiments facilitating cardiovascular research.

Identification of ZASP, a novel protein associated to Zona occludens-2.

With the aim of discovering new molecular interactions of the tight junction protein ZO-2, a two-hybrid screen was performed on a human kidney cDNA library using as bait the middle segment of ZO-2. Through this assay we identified a 24-kDa novel protein herein named ZASP for ZO-2 associated speckle protein. ZO-2/ZASP interaction further confirmed by pull down and immunoprecipitation experiments, requires the presence of the intact PDZ binding motif SQV of ZASP and the third PDZ domain of ZO-2. ZASP mRNA and protein are present in the kidney and in several epithelial cell lines. Endogenous ZASP is expressed primarily in nuclear speckles in co-localization with splicing factor SC-35. Nocodazole treatment and wash out reveals that ZASP disappears from the nucleus during mitosis in accordance with speckle disassembly during metaphase. ZASP amino acid sequence exhibits a canonical nuclear exportation signal and in agreement the protein exits the nucleus through a process mediated by exportin/CRM1. ZASP over-expression blocks the inhibitory activity of ZO-2 on cyclin D1 gene transcription and protein expression. The identification of ZASP helps to unfold the complex nuclear molecular arrays that form on ZO-2 scaffolds.

Motility patterns of Trypanosoma cruzi trypomastigotes correlate with the efficiency of parasite invasion in vitro.

Numerous works have demonstrated that trypanosomatid motility is relevant for parasite replication and sensitivity. Nonetheless, although some findings indirectly suggest that motility also plays an important role during infection, this has not been extensively investigated. This work is aimed at partially filling this void for the case of Trypanosoma cruzi. After recording swimming T. cruzi trypomastigotes (CL Brener strain) and recovering their individual trajectories, we statistically analyzed parasite motility patterns. We did this with parasites that swim alone or above monolayer cultures of different cell lines. Our results indicate that T. cruzi trypomastigotes change their motility patterns when they are in the presence of mammalian cells, in a cell-line dependent manner. We further performed infection experiments in which each of the mammalian cell cultures were incubated for 2 h together with trypomastigotes, and measured the corresponding invasion efficiency. Not only this parameter varied from cell line to cell line, but it resulted to be positively correlated with the corresponding intensity of the motility pattern changes. Together, these results suggest that T. cruzi trypomastigotes are capable of sensing the presence of mammalian cells and of changing their motility patterns accordingly, and that this might increase their invasion efficiency.

Handheld X-ray fluorescence geochemical data of geological and archaeological obsidian from Sonora, Mexico.

Geochemical detection using a portable XRF analyser is highly effective for nondestructive surface analysis in archaeological and geological obsidians. The data obtained in rock slabs, fragments, anhydrous nuclei, flaked and ground stone from Sonora, Mexico, were used to select certain analysed elements (Fe, Mn, Zr, Nb, Y, Th, Rb, Sr, Zn) that help to formulate geochemical variation diagrams to identify chemical trends and correlations between the samples. It proves to be an excellent analytical method for the provenance studies of archaeological artifacts. Subsequently, the integration of the obtained data here and their arrangement with the existing chemical analysis of obsidians for different localities of NW Mexico and the SW of the United States will allow for better knowledge of the primary sources of obsidian in the extraction and manufacture of archaeological artifacts.

Bistable behaviour and medium-dependent post-translational regulation of the tryptophanase operon regulatory pathway in Echerichia coli.

The present work is aimed at studying the dynamic behaviour of the tryptopnanase (tna) operon, which encodes the proteins necessary to uptake and metabolise tryptophan to use it as a carbon source in the absence of glucose. To this end, we designed a micro-bioreactor capable of driving a bacterial culture to a stationary state. This allowed us to explore (at the single cell level) the tna operon steady-state dynamics under multiple culture conditions. Our experimental results suggest that the tna operon is bistable for a specific range of environmental tryptophan and glucose concentrations, and evidence that both reagents play a role on the activation of the enzyme in charge of metabolising tryptophan: tryptophanase (TnaA). Based on our experimental data and the already known regulatory mechanisms, we developed a mathematical model for the tna operon regulatory pathway. Our modelling results reinforce the claim that the tna operon is bistable, and further suggest that the activity of enzyme TnaA is regulated by the environmental levels of glucose and tryptophan via a common signalling pathway. Possible biological implications of our findings are further discussed.

Relación entre la anemia infantil y el desempeño intelectual en la juventud

Objetivo: Determinar la relación que entre la anemia padecida por una generación cuando eran niños y su rendimiento en la prueba PISA a los 15 años de edad. Material y métodos: Se relacionó el puntaje que los jóvenes de cada país obtuvieron en la prueba PISA 2018 con la prevalencia de anemia infantil en 2005, el Ingreso Nacional Bruto per cápita y los Años Esperados de Escolaridad del Índice de Desarrollo Humano del año 2018. Resultados: El puntaje obtenido en la prueba PISA se relaciona con la anemia cuando niños, el Ingreso Nacional Bruto per cápita y los Años Esperados de Escolaridad (Esfuerzo Educativo) con coeficientes de determinación (r2) de 0.5168, 0.1951 y 0.3536, respectivamente. Conclusión: El puntaje obtenido en la prueba PISA se asocia con más fuerza con la prevalencia de anemia que padeció esa generación cuando eran niños que con cualquier otro factor económico o social actuales.

DFT study of anisotropy effects on the electronic properties of diamond nanowires with nitrogen-vacancy center.

In the development of quantum computing and communications, improvements in materials capable of single photon emission are of great importance. Advances in single photon emission have been achieved experimentally by introducing nitrogen-vacancy (N-V) centers on diamond nanostructures. However, theoretical modeling of the anisotropic effects on the electronic properties of these materials is almost nonexistent. In this study, the electronic band structure and density of states of diamond nanowires with N-V defects were analyzed through first principles approach using the density functional theory and the supercell scheme. The nanowires were modeled on two growth directions [001] and [111]. All surface dangling bonds were passivated with hydrogen (H) atoms. The results show that the N-V introduces multiple trap states within the energy band gap of the diamond nanowire. The energy difference between these states is influenced by the growth direction of the nanowires, which could contribute to the emission of photons with different wavelengths. The presence of these trap states could reduce the recombination rate between the conduction and the valence band, thus favoring the single photon emission. Graphical abstract Diamond nanowires with nitrogen-vacancy centerᅟ.

Motility of Escherichia coli in a quasi-two-dimensional porous medium.

Bacterial migration through confined spaces is critical for several phenomena, such as biofilm formation, bacterial transport in soils, and bacterial therapy against cancer. In the present work, E. coli (strain K12-MG1655 WT) motility was characterized by recording and analyzing individual bacterium trajectories in a simulated quasi-two-dimensional porous medium. The porous medium was simulated by enclosing, between slide and cover slip, a bacterial-culture sample mixed with uniform 2.98-µm-diameter spherical latex particles. The porosity of the medium was controlled by changing the latex particle concentration. By statistically analyzing several trajectory parameters (instantaneous velocity, turn angle, mean squared displacement, etc.), and contrasting with the results of a random-walk model developed ad hoc, we were able to quantify the effects that different obstacle concentrations have upon bacterial motility.

Influencia de los contaminantes dentro del cañón de un arma de fuego tipo escopeta en los resultados de la prueba de GRIESS (a y b) para la detección de residuos de disparo / Influência de contaminantes no interior do cano de uma arma de fogo do tipo espingarda nos resultados do teste GRIESS (a e b) para a detecção de resíduos de disparo / The Influence of Contaminants in a Shotgun Barrel on the Results of a Griess test (a and b) for Detecting Gunshot Residues

El presente estudio tuvo como objetivo general determinar el grado de afectación que presenta la prueba Griess (a y b), al interior del cañón del arma de fuego tipo escopeta, marca Benelli, modelo Súper Nova, con la trasmisión de los contaminantes aceite, agua lluvia, diésel y gasolina. Surge la necesidad de indagar si los contaminantes establecidos pueden afectar la realización del procedimiento descrito en el numeral 4.1 de la guía 2DCGU-0024 "realizar procedimientos balísticos a las armas (de fuego, neumáticas, de gas, fisto, detonadoras, eléctricas, entre otras) e ingreso a los sistemas de identificación balística". La metodología utilizada fue de tipo experimental, para ello se realizó una cantidad importante de ensayos, se manipularon las soluciones A y B del reactivo de GRIESS. Como resultado se evidenció que los agentes contaminantes transferidos al interior del cañón (aceite 4 tiempos, diésel y gasolina) no afectan los resultados para la identificación de nitritos producto de la combustión durante el fenómeno del disparo, caso contrario ocurre con el agua lluvia, ya que se observa que esta afecta la elaboración de la prueba, teniendo en cuenta que sin entrar en contacto con la pólvora deflagrada, arroja como resultado una coloración rosada tenue, que indica de forma preliminar que es positiva para la presencia de nitritos.

This study's general objective was to determine the degree of impact a GRIESS test (a and b) may have on the inside of a Benelli Supernova shotgun barrel by transmitting contaminants, such as oil, rain water, diesel and gasoline. The need arose to research whether or not the established contaminants can affect performing the procedure described in clause 4.1 of guide 2DC-GU-0024 on "performing ballistic testing on weapons (firearms, pneumatic, gas, black powder, detonating, electrical, etc.) and entering ballistic identification systems." The methodology was experimental. A high number of tests were carried out, manipulating components A and B of the GRIESS reagent. As a result, it was observed that contaminating agents transferred within a barrel (4-stroke engine oil, diesel and gasoline) do not affect the results of identifying nitrates resulting from combustion during firearm discharge. The opposite occurs with rain water, since it was observed that is affects preparing evidence, taking into account that it yields a light pink coloration as a result without coming into contact with combusted gunpowder, which preliminarily indicates that it tested positive for the presence of nitrites.

O objetivo geral do presente estudo foi determinar o grau de afetação que o teste de GRIESS (a e b) apresenta, dentro do cano da arma de fogo tipo espingarda, marca Benelli, modelo Super Nova, com a transmissão dos contaminantes: óleo, água da chuva, diesel e gasolina. Surge a necessidade de investigar se os contaminantes estabelecidos podem afetar o desempenho do procedimento descrito no numeral 4.1 do guia 2DC-GU-0024 "realizar procedimentos balísticos em armas (armas de fogo, pneumáticas, gás, fisto, detonantes, elétricos, entre outros) e acesso a sistemas de identificação balística". A metodologia utilizada foi experimental, nesse sentido, foi realizado um número significativo de testes, e as soluções A e B do reagente de GRIESS foram manipuladas. Como resultado, ficou evidente que os agentes contaminantes transferidos para o interior do cano (óleo 4 tempos, diesel e gasolina) não afetam os resultados para a identificação de nitritos produto da combustão durante o fenômeno de queima. O contrário ocorre com a água da chuva, pois observa-se que isso afeta o preparo do teste, visto que, sem entrar em contato com a pólvora deflagrada, produz uma leve coloração rosa, o que preliminarmente indica que é positivo para a presença de nitritos.

Short-time dynamics of monomers and dimers in quasi-two-dimensional colloidal mixtures.

We report on the short-time dynamics in colloidal mixtures made up of monomers and dimers highly confined between two glass plates. At low concentrations, the experimental measurements of colloidal motion agree well with the solution of the Navier-Stokes equation at low Reynolds numbers; the latter takes into account the increase in the drag force on a colloidal particle due to wall-particle hydrodynamic forces. More importantly, we find that the ratio of the short-time diffusion coefficient of the monomer and that of the center of mass of the dimmer is almost independent of both the dimer molar fraction, x_{d}, and the total packing fraction, ϕ, up to ϕ≈0.5. At higher concentrations, this ratio displays a small but systematic increase. A similar physical scenario is observed for the ratio between the parallel and the perpendicular components of the short-time diffusion coefficients of the dimer. This dynamical behavior is corroborated by means of molecular dynamics computer simulations that include explicitly the particle-particle hydrodynamic forces induced by the solvent. Our results suggest that the effects of colloid-colloid hydrodynamic interactions on the short-time diffusion coefficients are almost identical and factorable in both species.

Experimental and Mathematical-Modeling Characterization of Trypanosoma cruzi Epimastigote Motility.

The present work is aimed at characterizing the motility of parasite T. cruzi in its epimastigote form. To that end, we recorded the trajectories of two strains of this parasite (a wild-type strain and a stable transfected strain, which contains an ectopic copy of LYT1 gene and whose motility is known to be affected). We further extracted parasite trajectories from the recorded videos, and statistically analysed the following trajectory-step features: step length, angular change of direction, longitudinal and transverse displacements with respect to the previous step, and mean square displacement. Based on the resulting observations, we developed a mathematical model to simulate parasite trajectories. The fact that the model predictions closely match most of the experimentally observed parasite-trajectory characteristics, allows us to conclude that the model is an accurate description of T. cruzi motility.

Short-time dynamics of colloidal particles confined between two walls.

The short-time dynamics of colloidal particles in a quasi-two-dimensional geometry is studied by digital video microscopy. The particles (polystyrene spheres) are suspended in water and confined between two parallel glass plates, forming an effective two-dimensional system. The (effective) two-dimensional van Hove function G(r,t) and its self and distinct part are measured with a time resolution of 1/30 s. We found that the general behavior of these time-correlation functions (and their Fourier transforms) is quite similar to that of their three-dimensional counterparts. The effects of the strong hydrodynamic coupling of the particles motion to the walls and that due to the hydrodynamic interactions between particles are contained in the (effective) hydrodynamic function H(k) obtained from the initial slope of F(k,t) [the Fourier transform of G(r,t)]. We found that H(k), as a function of the wave vector k and particle concentration, exhibits a similar qualitative behavior to the hydrodynamic function in homogeneous three-dimensional suspensions of hard spheres. We also found in our systems that the particle fluctuations relax only by self-diffusion for wave vectors where the static structure factor S(k)=1. This result is important for measurements of self-diffusion dynamics in three-dimensional systems by light scattering techniques.

Effective pair potential between confined charged colloidal particles.

The pair correlation function g(r) between like-charged colloidal particles in quasi-two-dimensional geometries is measured by optical microscopy for a wide range of particle concentrations and various degrees of confinement. The effective pair potential u(r) is obtained by deconvoluting g(r) via Monte Carlo computer simulations. Our results confirm the existence of a long-range attractive component of u(r) and the appearance of an extra attractive term under stringent confinement.

Prevalencia de anemia en gestantes de la ciudad de Huacho / Prevalence of anemia in pregnant women in Huacho city

Objetivo. Mostrar la prevalencia de anemia crónica en gestantes según nivel educativo y según procedencia geográfica urbana o rural. Material y Métodos. Análisis de una base de datos (Sistema Informático Perinatal, una base de datos proporcionada por el Centro Latinoamericano de Perinatología) de los años 2001 a 2010 que incluye un total de 27 184 embarazos, mediante la elaboración de cuadros y la aplicación de pruebas de significancia estadística. resultados. La prevalencia de anemia crónica en las gestantes fue 23,7 % como promedio de la década, pero fue 27 % en las gestantes urbanas y 10,1 % en las gestantes de poblaciones rurales recientes (OR 3,28; IC 95%; 2,66-4,04; p = 0,0000001). Según nivel de estudios: ninguno 24,1 %; primaria 20,4 %; secundaria 24,6 %; y, superior 22,4 %. Conclusión. Se encontró mayor prevalencia de anemia crónica en las gestantes urbanas que en las gestantes rurales.

Objectives. To show the prevalence of chronic anemia in pregnant women by educational level and geographical origin as urban or rural. Material and Methods. Analysis of a database (Sistema Informático Perinatal, a program provided by the Centro Latinoamericano de Perinatología) for the years 2001 to 2010, and included a total of 27 184 pregnancies, preparing tables and applying statistical significance tests. results. The prevalence of chronic anemia in pregnant women was 23,7 % on average in the decade, but 27 % in urban pregnant women and 10,1 % in pregnant women of recent rural population (OR 3,28, 95% CI 2,66-4,04; p =0,0000001). According to educational level: none 24,1 %; primary 20,4 %; secondary 24,6 %; and, superior 22,4 %. Conclusion. There was a higher prevalence of chronic anemia in urban pregnant women than in rural pregnant women.

Direct measurement of colloidal particle rotation and field dependence in alternating current electrohydrodynamic flows.

We have measured the influence of both applied alternating current (AC) field strength and frequency on the electrohydrodynamic (EH) flows present in colloidal systems near an electrode surface. The effect of the flows is visualized by the rotation of the colloids, fluorescently labeled by a novel technique involving EH-driven aggregation of much smaller tracer colloids to the surface of the larger colloids. Our results show an E2 dependence of these flows, consistent with an induced charge mechanism for effective colloidal interactions. We have also observed a crossover in frequency that suggests a change in the origin of the induced charge, consistent with predictions from available theory. The EH flows appear to be hydrodynamically screened inside clusters, as evidenced by the lack of rotation of interior colloids and the cluster-size independent rotation rate of colloids on the boundary.

Short-time dynamics in quasi-two-dimensional colloidal suspensions.

The short-time dynamic properties of colloidal particles in quasi-two-dimensional geometries are studied by digital video microscopy. We demonstrate experimentally that the effective-two-dimensional physical quantities such as the dynamic structure factor, the hydrodynamic function, and the hydrodynamic diffusion coefficients are related in exactly the same manner as their three-dimensional counterparts.