Nanoconfinement and Crowding Enhanced Single-Molecule Detection of Small Molecules with Nanopipettes.

Glass nanopipettes have gained widespread use as a versatile single-entity detector in chemical and biological sensing, analysis, and imaging. Its advantages include low cost, easy accessibility, simplicity of use, and high versatility. However, conventional nanopipettes based on the volume exclusion mechanism have limitations in detecting small biomolecules due to their small volume and high mobility in aqueous solution. To overcome this challenge, we have employed a novel approach by capitalizing on the strong nanoconfinement effect of nanopipettes. This is achieved by utilizing both the hard confinement provided by the long taper nanopipette tip at the cis side and the soft confinement offered by the hydrogel at the trans side. Through this approach, we have effectively slowed down the exit motion of small molecules, allowing us to enrich and jam them at the nanopipette tip. Consequently, we have achieved high throughput detection of small biomolecules with sizes as small as 1 nm, including nucleoside triphosphates, short peptides, and small proteins with excellent signal-to-noise ratios. Furthermore, molecular complex formation through specific intermolecular interactions, such as hydrogen bonding between closely spaced nucleotides in the jam-packed nanopipette tip, has been detected based on the unique ionic current changes.

Anticancer Drug Doxorubicin Spontaneously Reacts with GTP and dGTP.

Here, we reported a spontaneous reaction between anticancer drug doxorubicin and GTP or dGTP. Incubation of doxorubicin with GTP or dGTP at 37 °C or above yields a covalent product: the doxorubicin-GTP or -dGTP conjugate where a covalent bond is formed between the C14 position of doxorubicin and the 2-amino group of guanine. Density functional theory calculations show the feasibility of this spontaneous reaction. Fluorescence imaging studies demonstrate that the doxorubicin-GTP and -dGTP conjugates cannot enter nuclei although they rapidly accumulate in human SK-OV-3 and NCI/ADR-RES cells. Consequently, the doxorubicin-GTP and -dGTP conjugates are less cytotoxic than doxorubicin. We also demonstrate that doxorubicin binds to ATP, GTP, and other nucleotides with a dissociation constant (Kd) in the sub-millimolar range. Since human cells contain millimolar levels of ATP and GTP, these results suggest that doxorubicin may target ATP and GTP, energy molecules that support essential processes in living organisms.

Exploring the Conformational and Binding Dynamics of HMGA2·DNA Complexes Using Trapped Ion Mobility Spectrometry-Mass Spectrometry.

The mammalian high mobility group protein AT-hook 2 (HMGA2) is an intrinsically disordered DNA-binding protein expressed during embryogenesis. In the present work, the conformational and binding dynamics of HMGA2 and HMGA2 in complex with a 22-nt (DNA22) and a 50-nt (DNA50) AT-rich DNA hairpin were investigated using trapped ion mobility spectrometry-mass spectrometry (TIMS-MS) under native starting solvent conditions (e.g., 100 mM aqueous NH4Ac) and collision-induced unfolding/dissociation (CIU/CID) as well as solution fluorescence anisotropy to assess the role of the DNA ligand when binding to the HMGA2 protein. CIU-TIMS-CID-MS/MS experiments showed a significant reduction of the conformational space and charge-state distribution accompanied by an energy stability increase of the native HMGA2 upon DNA binding. Fluorescence anisotropy experiments and CIU-TIMS-CID-MS/MS demonstrated for the first time that HMGA2 binds with high affinity to the minor groove of AT-rich DNA oligomers and with lower affinity to the major groove of AT-rich DNA oligomers (minor groove occupied by a minor groove binder Hoechst 33258). The HMGA2·DNA22 complex (18.2 kDa) 1:1 and 1:2 stoichiometry suggests that two of the AT-hook sites are accessible for DNA binding, while the other AT-hook site is probably coordinated by the C-terminal motif peptide (CTMP). The HMGA2 transition from disordered to ordered upon DNA binding is driven by the interaction of the three basic AT-hook residues with the minor and/or major grooves of AT-rich DNA oligomers.

Longitudinal zonation pattern in Arabidopsis root tip defined by a multiple structural change algorithm.

Background and Aims The Arabidopsis thaliana root is a key experimental system in developmental biology. Despite its importance, we are still lacking an objective and broadly applicable approach for identification of number and position of developmental domains or zones along the longitudinal axis of the root apex or boundaries between them, which is essential for understanding the mechanisms underlying cell proliferation, elongation and differentiation dynamics during root development. Methods We used a statistics approach, the multiple structural change algorithm (MSC), for estimating the number and position of developmental transitions in the growing portion of the root apex. Once the positions of the transitions between domains and zones were determined, linear models were used to estimate the critical size of dividing cells (LcritD) and other parameters. Key Results The MSC approach enabled identification of three discrete regions in the growing parts of the root that correspond to the proliferation domain (PD), the transition domain (TD) and the elongation zone (EZ). Simultaneous application of the MSC approach and G2-to-M transition (CycB1;1DB:GFP) and endoreduplication (pCCS52A1:GUS) molecular markers confirmed the presence and position of the TD. We also found that the MADS-box gene XAANTAL1 (XAL1) is required for the wild-type (wt) PD increase in length during the first 2 weeks of growth. Contrary to wt, in the xal1 loss-of-function mutant the increase and acceleration of root growth were not detected. We also found alterations in LcritD in xal1 compared with wt, which was associated with longer cell cycle duration in the mutant. Conclusions The MSC approach is a useful, objective and versatile tool for identification of the PD, TD and EZ and boundaries between them in the root apices and can be used for the phenotyping of different genetic backgrounds, experimental treatments or developmental changes within a genotype. The tool is publicly available at www.ibiologia.com.mx/MSC_analysis.

Etilefrina vs fenilefrina en hipotensión por anestesia espinal para cesárea: ensayo clínico multicéntrico, controlado, aleatorizado y doble ciego / Etilefrine vs. phenylephrine for hypotension during spinal anesthesia for cesarean section: Multicenter, randomized, double blind controlled clinical trial

Introduction: Hypotension after spinal anesthesia in cesarean section should be minimized. The use of vasopressors is an effective measure to treat hypotension. The objective of this paper is to compare the safety and effectiveness of etilefrine vs. phenylephrine in the management of this condition. Methods: This multicenter, double-blind trial between August 2009 and November 2010 included 196 patients with hypotension during spinal anesthesia for cesarean delivery; the patients were randomized to receive etilefrine or phenylephrine as vasopressor. The primary outcome was the fetal umbilical arterial pH. The secondary outcomes were: fetal acidosis (umbilical arterial pH < 7.20), Apgar score at 1 and 5 min, need for intubation and admission to the neonatal intensive care unit for newborns, and time of hypotension, total dose of vasopressor, atropine requirement, intravenous fluids volume and incidence of nausea and vomiting in mothers. Results: 98 patients received etilefrine and 98 phenylephrine. There were no differences in umbilical arterial pH (7.27 vs. 7.28, respectively, P = 0.493). The total dose of vasopressor (5.66 vs. 6.51ml, respectively, P = 0.024) and total time of hypotension (2.78 vs. 3.25 min, respectively, P = 0.021) were lower in the etilefrine group. Other outcomes studied showed no statistically significant differences. Conclusion: Etilefrine and phenylephrine are equally effective for the treatment of hypotension during spinal anesthesia for cesarean delivery. This study found no difference in the maternal or fetal outcomes.

Introducción: La hipotensión que ocurre luego de anestesia espinal para cesárea debe minimizarse. El uso de vasopresores es una medida eficaz para su tratamiento. El objetivo de este trabajo es comparar la seguridad y efectividad de etilefrina vs fenilefrina para manejo de esta condición. Métodos: En este estudio multicéntrico y doble ciego, entre agosto de 2009 y noviembre de 2010, 196 pacientes con hipotensión durante anestesia espinal para cesárea, fueron asignadas aleatoriamente para recibir etilefrina o fenilefrina como vasopresor. El resultado primario fue el pH arterial umbilical fetal. Los resultados secundarios fueron: acidosis fetal (pH arterial umbilical < 7,20), puntaje Apgar al 1 y 5 minutos, necesidad de intubación e ingreso a la unidad de cuidados intensivos neonatal para los recién nacidos; y tiempo de hipotensión, dosis total de vasopresor, necesidad de uso de atropina, líquidos endovenosos totales e incidencia de nausea y vómito para las madres. Resultados: 98 pacientes recibieron etilefrina y 98 fenilefrina. No se encontraron diferencias en el pH arterial umbilical (7,27 vs 7,28 respectivamente; p = 0,493). La dosis total de vasopresor (5,66 vs. 6,6 ml, respectivamente; P = 0,024) y el tiempo total de hipotensión (2,78 vs. 3,25 min, respectivamente; p = 0,021), fueron menores en el grupo de etilefrina. Los demás desenlaces estudiados no presentaron diferencia estadísticamente significativa. Conclusión: La etilefrina y la fenilefrina son igualmente efectivas para el tratamiento de la hipotensión por anestesia espinal para cesárea. Este estudio no encontró diferencia en los resultados fetales ni maternos.

Effects of salinity on growth and survival in five Artemia franciscana (Anostraca: Artemiidae) populations from Mexico Pacific Coast.

Salinity is an important factor influencing growth and survival of aquatic organisms such as Artemia, a valuable aquaculture species. This study evaluated the effects of salinity on A. franciscana populations from different water bodies in Mexico's Pacific Coast. With this purpose, five autochthonous bisexual Artemia populations were tested to assess their survival and growth values against salinities of 40, 60, 80, 100 and 120 g/l, under laboratory conditions (25 +/- 2 degrees C; pH 8-10; constant light and aeration). The organisms were fed with 100 mL of rice bran and 2L of Tetraselmis suecica (500 000 cel/ml). The culture experiments were made in 200L plastic tanks, and survival and growth final values were obtained after 21 culture days. Survival and growth curves were determined by a regression analysis (R2). The significant differences between salinities were determined by ANOVA test (p < 0.05). The best survival and growth rates were found at salinities of 100-120 g/l. When the Mexican Artemia populations were cultivated at 40 g/l of salinity, 100% mortality was observed in the juvenile stage. This study determined that survival and growth values of A. franciscana populations increased with salinity. The five A. franciscana populations presented significant differences in their survival rate under various salinity regimes. The studied populations experienced high mortality at salinities under 60 g/l and over 200 g/l, and especially during the metanauplius stage. The present study confirms that growth rates in Mexican A. franciscana populations from Pacific Coast habitats are not inversely proportional to salinity. These A. franciscana populations should be cultured at 100-120 g/l of salinity to obtain better survival and growth rates. This data is useful to improve culture systems in aquaculture biomass production systems.

Effects of salinity on growth and survival in five Artemia franciscana (Anostraca: Artemiidae) populations from Mexico Pacific Coast

Salinity is an important factor influencing growth and survival of aquatic organisms such as Artemia, a valuable aquaculture species. This study evaluated the effects of salinity on A. franciscana populations from different water bodies in Mexico’s Pacific Coast. With this purpose, five autochthonous bisexual Artemia populations were tested to assess their survival and growth values against salinities of 40, 60, 80, 100 and 120g/l, under laboratory conditions (25±2ºC; pH 8-10; constant light and aeration). The organisms were fed with 100mL of rice bran and 2L of Tetraselmis suecica (500 000cel/ml). The culture experiments were made in 200L plastic tanks, and survival and growth final values were obtained after 21 culture days. Survival and growth curves were determined by a regression analysis (R²). The significant differences between salinities were determined by ANOVA test (p<0.05). The best survival and growth rates were found at salinities of 100-120g/l. When the Mexican Artemia populations were cultivated at 40g/l of salinity, 100% mortality was observed in the juvenile stage. This study determined that survival and growth values of A. franciscana populations increased with salinity. The five A. franciscana populations presented significant differences in their survival rate under various salinity regimes. The studied populations experienced high mortality at salinities under 60g/l and over 200g/l, and especially during the metanauplius stage. The present study confirms that growth rates in Mexican A. franciscana populations from Pacific Coast habitats are not inversely proportional to salinity. These A. franciscana populations should be cultured at 100-120g/l of salinity to obtain better survival and growth rates. This data is useful to improve culture systems in aquaculture biomass production systems. Rev. Biol. Trop. 59 (1): 199-206. Epub 2011 March 01.

La salinidad es el factor más importante que modifica el crecimiento y la sobrevivencia de las poblaciones mexicanas de Artemia en el mundo. El efecto de este factor en las poblaciones costeras del Pacífico Mexicano ha sido poco estudiado. Cinco poblaciones bisexuales de Artemia provenientes de cuerpos de aguas costeras del Pacífico Mexicano, se estudiaron para determinar el efecto que tiene la salinidad de 40, 60, 80, 100 y 120g/l sobre la sobrevivencia y el crecimiento, en condiciones de laboratorio (25±2ºC, pH 8-10; luz y aireación continua). Los experimentos de cultivo fueron realizados en tanques de plástico de 200l. Los valores finales de sobrevivencia y crecimiento fueron determinados después de 21 días de cultivo. Los organismos fueron alimentados con 100ml de salvado de arroz y 2l de Tetraselmis suecica (500cel/ml). Las curvas de sobrevivencia y crecimiento fueron determinadas usando un análisis de regresión (R²). Las diferencias significativas entre los valores promedio a las distintas salinidades fueron determinadas por una prueba de ANDEVA (p<0.05). Las mejores tasa de sobrevivencia y crecimiento se encontraron a la salinidad de 100-120g/l. Cuando las poblaciones mexicanas fueron cultivadas a 40 g/l de salinidad, hubo una mortalidad del 100% de los organismos en estadio juvenil. A la salinidad de 80g/l, los valores de sobrevivencia y crecimiento, fueron menores que cuando se cultivaron entre 100 y 120g/l. Las cinco poblaciones bisexuales de A. franciscana presentaron diferencias significativas en sus tasas de sobrevivencia bajo las salinidades estudiadas. Las tasas de sobrevivencia fueron afectadas por la salinidad. Las poblaciones estudiadas experimentaron alta mortalidad a salinidades por debajo de 60 g/l y por arriba de 200g/l. Es importante mencionar que las altas mortalidades se observaron en el estadio metanauplios. El presente trabajo confirma que las tasas de crecimiento de las poblaciones que costeras del Pacífico Mexicano de A. franciscana no son inversamente proporcionales a la salinidad. Las poblaciones de A. franciscana deben de ser cultivadas a una salinidad de 100-120g/l para obtener mejores tasas de sobrevivencia y crecimiento. Estos datos permiten realizar mejoras en los sistemas de cultivo de este crustáceo para la obtención de biomasa para la acuicultura.

Revisión de las normas de bioseguridad en la atención odontológica, con un enfoque en VIH/SIDA / Review of infection control regulations in dental care with an emphasis in HIV/AIDS

Se presentan en este artículo recomendaciones para la atención odontológica de personas infectadas con VIH/SIDA y las normas para prevenir y controlar incidentes, accidentes laborales e infecciones relacionados con la práctica odontológica. Las recomendaciones están basadas en normas actualizadas de bioseguridad, y en los procesos de elaboración de la historia clínica según la Organización Mundial de la Salud (OMS), el Centro para el Control y Prevención de Enfermedades (CDC), la Administración para la Seguridad y la Salud Ocupacional (OSHA) de los Estados Unidos, la Asociación Dental Americana (ADA), y el Ministerio de la Protección Social colombiano.

This article introduces recommendations for the dental care of patients infected with HIV/AIDS, and the norms to prevent and control incidents, work accidents and infections related to the dental practice. The recommendations are based on current standards for infection control and the preparation of medical records from the World Health Organization (WHO), the U.S. Center for Disease Control (CDC), the U.S. Occupational Security and Health Administration (OSHA), the American Dental Association (ADA) and the Colombian Ministry of Health.

[Composition of fat acids in three Mexican populations of Artemia franciscana from epicontinental waters]. / Composici6n del contenido de ácidos grasos en tres poblaciones mexicanas de Artemia franciscana de aguas epicontinentales.

In this paper is presented the percentage of fatty acids composition of three Artemia franciscana Mexican populations of epicontinentals waters; two are from natural environments (Coahuila and San Luis Potosf) and one (Texcoco) is a culture fed with Spirulina. Determination of fatty acids composition in each population, was performed by extraction of total lipid by the soxhlet method and the fatty acids methyl esters were determined by gas chromatography. The results show that Artemia of Texcoco contains the six fatty acids recommended for the culture of fish and crustaceans (16:0; 16:1; 18:1; 18:2w6; 18:3w3 and 20:5w3); Artemia from San Luis Potosi showed the poorest content in these acids and Artemia from Coahuila, although it showed a wide profile, it lacks the linolenic acid. When comparing results among the three populations with ecological data that have been published, it can be pointed out that the environment is decisive for this crustacean; Artemia from Texcoco fed with Spirulina showed the largest variety of fatty acids; the other two populations are wild, and lives in different habitats, Artemia of Coahuila is found in waters that are rich in sulfates and Artemia of San Luis Potosf lives in evaporation saltern ponds, built with stone blocks and therefore with scarce phytoplankton growth. Both Artemia populations showed deficiencies in essential fatty acids, mainly the last one.

Trauma de columna cervical: manejo de la via aérea / Cervical spine trauma: treatment of the aerial way

En general la técnica de elección para asegurar la vía aérea está determinada por el estado del paciente, el sitio de atención, el grado de urgencia y por la destreza del anestesiologo. En situaciones de extrema urgencia, la laringoscopia directa es preferida por la rapidez, siempre teniendo en cuenta la estabilización en linea; las técnicas fibropticas con el paciente despierto son las preferidas según la literatura, en casos menos urgentes y electivos ya que permiten la evaluación neurológica y no exigen el retiro de los inmovilizadores. Siempre deben existir planes alternos bien estructurados con el fin de evitar complicaciones catastróficas que empeoren el pronóstico neurológico de los pacientes. De todos los dispositivos supraglóticos, el Combitubo es el que produce el mayor desplazamiento de la columna cervical (3 a 9 mm), razón por la cual no es recomendado en situaciones electivas.