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1.
bioRxiv ; 2024 Apr 29.
Artículo en Inglés | MEDLINE | ID: mdl-38746087

RESUMEN

Eukaryotic ribosome assembly is an intricate process that involves four ribosomal RNAs, 80 ribosomal proteins, and over 200 biogenesis factors that take part in numerous interdependent steps. This complexity creates a large genetic space in which pathogenic mutations can occur. Dead-end ribosome intermediates that result from biogenesis errors are rapidly degraded, affirming the existence of quality control pathway(s) that monitor ribosome assembly. However, the factors that differentiate between on-path and dead-end intermediates are unknown. We engineered a system to perturb ribosome assembly in human cells and discovered that faulty ribosomes are degraded via the ubiquitin proteasome system. We identified ZNF574 as a key component of a novel quality control pathway, which we term the Ribosome Assembly Surveillance Pathway (RASP). Loss of ZNF574 results in the accumulation of faulty biogenesis intermediates that interfere with global ribosome production, further emphasizing the role of RASP in protein homeostasis and cellular health.

2.
Small ; : e2312215, 2024 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-38497820

RESUMEN

The systematic structure modification of metal oxides is becoming more attractive, and effective strategies for structural tunning are highly desirable for improving their practical color-modulating energy storage performances. Here, the ability of a stoichiometrically tuned oxide-hydroxide complex of porous vanadium oxide, namely [V2 O2+ξ (OH)3-ξ ]ξ = 0:3 for multifunctional electrochromic supercapacitor application is demonstrated. Theoretically, the pre-optimized oxide complex is synthesized using a simple wet chemical etching technique in its optimized stoichiometry [V2 O2+ξ (OH)3-ξ ] with ξ = 0, providing more electroactive surface sites. The multifunctional electrode shows a high charge storage property of 610 Fg-1 at 1A g-1 , as well as good electrochromic properties with high color contrast of 70% and 50% at 428 and 640 nm wavelengths, faster switching, and high coloration efficiency. When assembled in a solid-state symmetric electrochromic supercapacitor device, it exhibits an ultrahigh power density of 1066 mWcm-2 , high energy density of 246 mWhcm-2 , and high specific capacitance of 290 mFcm-2 at 0.2 mAcm-2 . A prepared prototype device displays red when fully charged, green when half charged, and blue when fully discharged. A clear evidence of optimizing the multifunctional performance of electrochromic supercapacitor by stoichiometrical tuning is presented along with demonstrating a device prototype of a 25 cm2 large device for real-life applications.

3.
ACS Appl Mater Interfaces ; 15(23): 28453-28464, 2023 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-37266923

RESUMEN

Here, we report the design and synthesis of a redox-active multifunctional ionic porous organic polymer iPOP-Bpy with exchangeable Br- ions, incorporating viologen as a redox-active building block. The material shows not only excellent iodine uptake capacity in the vapor phase (540 wt %) but also in the organic (1009.77 mg g-1) and aqueous phases (3921.47 mg g-1) with very fast adsorption kinetics in all cases. The material also shows its utility in being used as a solid-state NH3 vapor sensor as it shows very fast color switching in the presence of NH3 vapor. Furthermore, the material found application as a p-type complementary electrochromic electrode and was fabricated into a bilayer device. Excellent coloration efficiency, high switching speed, and good color contrast were obtained as investigated using bias-dependent optical and spectroelectrochemical studies, paving the way for fabricating power-efficient solid-state electrochromic devices.

4.
Phys Chem Chem Phys ; 25(3): 1627-1631, 2023 Jan 18.
Artículo en Inglés | MEDLINE | ID: mdl-36601877

RESUMEN

It is always interesting to understand how the interplay between two perturbations, affects any physical process and gets manifested in a semiconductor. Temperature- and wavelength-dependent Raman Spectromicroscopy was performed on heavily-doped Si to reveal an unusual anti-anharmonic effect. Additionally, the energy dispersive behaviour of Fano coupling strength was also studied and its possible interrelation with the observed anti-anharmonic effect was explored. A systematic study revealed that at the different excitation wavelengths, the strength of the Fano interaction was different, where the involved electron-phonon (Fano-Fano-interferon) bound states were counted together with different energies. By understanding how the interplay manifests in terms of the Raman line shape, a method to calculate the Fano-interferon dissociation energy was developed. The slope of the Raman linewidth at different excitation wavelengths with temperature showed a negative temperature coefficient and sign reversal on decreasing the doping concentration. A wavelength-dependent empirical relation is proposed to calculate the required thermal energy, required to dissociate the electron-phonon bound state.

5.
J Med Case Rep ; 16(1): 482, 2022 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-36575475

RESUMEN

BACKGROUND: Fetal midgut volvulus is an uncommon yet potentially life-threatening condition. Prenatal diagnosis may pose a challenge, due to the paucity of specific signs and symptoms. Timely prenatal diagnosis of this condition is imperative to prevent fetal mortality and morbidity. CASE PRESENTATION: We present a rare case report of fetal midgut volvulus, malrotation, and intestinal obstruction at 32 weeks of gestation in a 31-year-old multigravida Indian patient who presented with decreased fetal movements. Fetal ultrasound revealed midgut volvulus with proximal bowel obstruction and polyhydramnios. The patient underwent emergency surgery, which revealed intestinal malrotation and confirmed the diagnosis of midgut volvulus. Untwisting of the volvulus was done followed by Ladd's procedure. Follow-up postoperative ultrasound was unremarkable. CONCLUSIONS: Delay in the diagnosis of fetal midgut volvulus leads to poor fetal and maternal outcomes. Hence, it is vital for radiologists, sonologists, and obstetricians to be aware of this condition while performing fetal sonography. Prompt diagnosis and surgical intervention are vital to reduce the morbidity and mortality associated with this condition.


Asunto(s)
Obstrucción Intestinal , Vólvulo Intestinal , Embarazo , Femenino , Humanos , Adulto , Vólvulo Intestinal/diagnóstico por imagen , Vólvulo Intestinal/cirugía , Vólvulo Intestinal/complicaciones , Diagnóstico Prenatal , Obstrucción Intestinal/etiología , Ultrasonografía Prenatal/efectos adversos , Feto
6.
J Phys Chem Lett ; : 5232-5239, 2022 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-35670640

RESUMEN

A nonlinear Fano interaction has been reported here which is manifest in terms of a parabolic temperature-dependent phonon decay process observable in terms of a Raman spectral parameter. Temperature-dependent Raman spectroscopic studies have been carried out on heavily and moderately doped crystalline silicon to investigate the behavior of anharmonic phonon decay in semiconductor systems where Fano interactions are present inherently. Systematic study reveals that in heavily doped systems an interferon-mediated decay route exists for cold phonons present at lower temperatures (<475 K) where Fano coupling is stronger and dominates over the typical multiple-phonon decay process. On the other hand, the anharmonic phonon decay remains the predominant process at higher temperatures irrespective of the doping level. Temperature-dependent phonon self-energy has been calculated using experimentally observed Raman line-shape parameters to validate the fact that the nonlinear decay of phonons through interferon mediation is a thermodynamically favorable process at low temperatures.

7.
Anal Chem ; 94(3): 1510-1514, 2022 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-34994546

RESUMEN

The Fermi energy is known to be dependent on doping and temperature, but finding its value and corresponding thermal Fermi shift experimentally is not only difficult but is virtually impossible if one attempts their simultaneous determination. We report that temperature dependent Raman spectromicroscopy solves the purpose easily and proves to be a powerful technique to determine the position and temperature associated Fermi shift in an extrinsic semiconductor as demonstrated for silicon in the present study. The typical asymmetrically broadened Raman spectral line-shape from sufficiently doped n- and p-type silicon contains the information about the Fermi level position through its known association with the Fano coupling strength. Thus, Raman line-shape parameters, the terms quantify the Fano-coupling, have been used as experimental observables to reveal the value of the Fermi energy and consequent thermal Fermi shift. A simple formula has been developed based on existing established theoretical frameworks that can be used to calculate the position of the Fermi level. The proposed Raman spectroscopy-based formulation applies well for n- and p-type silicon. The calculated Fermi level position and its temperature dependent variation are consistent with the existing reports.

8.
ACS Mater Au ; 2(3): 293-300, 2022 May 11.
Artículo en Inglés | MEDLINE | ID: mdl-36855378

RESUMEN

A dual purpose solid state electrochromic diode has been fabricated using polythiophene (P3HT) and ethyl Viologen (EV), predoped with multiwalled carbon nanotubes (MWCNTs) and MoS2. The device has been designed by considering two important aspects, first, the complementary redox activity of P3HT and EV and second, the electron holding properties of MoS2 and MWCNTs. The latter is found to enhance the electrochromic performance of the solid state device. On the other hand, the complementary redox nature gives the asymmetric diodic I-V characteristic to the device which has been exploited to use the electrochromic device for rectification application. The MoS2 nanoflower and MWCNTs are synthesized by one-step hydrothermal and pyrolysis techniques and well characterized by scanning electron microscopy (SEM), X-ray analysis (XRD), and Raman spectroscopy. Electrochromic properties of the device have been studied in detail to reveal an improvement in device performance in terms of faster speed and high coloration efficiency and color contrast. In situ bias-dependent Raman spectroscopy has been performed to understand the operation mechanism of the electrochromic diode which reveals (bi-)polaron formation as a result of dynamic doping eventually leading to color change. A half-wave rectifier has been realized from the electrochromic diode which rectifies an AC voltage of frequency 1 Hz or less making it suitable for low frequency operation. The study opens a new possibility to design and fabricate multipurpose frequency selective electrochromic rectifiers.

9.
ACS Phys Chem Au ; 2(5): 417-422, 2022 Sep 28.
Artículo en Inglés | MEDLINE | ID: mdl-36855687

RESUMEN

Excitation wavelength-dependent Raman spectroscopy has been carried out to study electron-phonon interaction (Fano resonance) in multi-layered bulk 2H-MoS2 nano-flakes. The electron-phonon coupling is proposed to be caused due to interaction between energy of an excitonic quasi-electronic continuum and the discrete one phonon, first-order Raman modes of MoS2. It is proposed that an asymmetrically broadened Raman line shape obtained by 633 nm laser excitation is due to electron-phonon interaction whose electronic continuum is provided by the well-known A and B excitons. Typical wavelength-dependent Raman line shape has been observed, which validates and quantifies the Fano interaction present in the samples. The experimentally obtained Raman scattering data show very good agreement with the theoretical Fano-Raman line-shape functions and help in estimating the coupling strength. Values of the electron-phonon interaction parameter obtained, through line-shape fitting, for the two excitation wavelengths have been compared and shown to have generic Fano-type dependence on the excitation wavelength.

10.
ACS Appl Bio Mater ; 4(8): 5981-5986, 2021 08 16.
Artículo en Inglés | MEDLINE | ID: mdl-35006870

RESUMEN

Optical and electrochemical properties from Cassia and Giloy leaves' raw extract have been studied, and they show similar properties as UV absorber but different emission properties, under UV excitation, even though they appear the same in natural light. Giloy and Cassia extracts show red and green luminescence, respectively, under UV excitation. Like the appearance, their redox properties are also similar, which shows that both can act as antioxidants. Raman spectroscopy and excitation wavelength dependent photoluminescence data have been compared. The difference in relative emission intensities have been explained based on the presence of corresponding color centers in different ratios in the two leaves.


Asunto(s)
Cassia , Senna , Tinospora , Cassia/química , Luminiscencia , Extractos Vegetales/análisis , Hojas de la Planta/química , Tinospora/química
12.
RSC Adv ; 10(39): 22983-22995, 2020 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-35520319

RESUMEN

Production of carbon fibers (CF) using renewable precursors has gained importance particularly in the last decade to reduce the dependency on conventional petroleum-based precursors. However, pre-treatment of these renewable precursors is still similar to that of conventional ones. Little work is put into greener pre-treatments and their effects on the end products. This work focuses on the use of bio-cleaned lignin as a green precursor to produce CF by electrospinning. Bio-cleaned kraft lignin A (Bio-KLA) and uncleaned kraft lignin A (KLA) were used to explore the effect of bio-cleaning on the diameter and mechanical properties of lignin fibers and CF. The effect of electric field, lignin-to-poly(ethylene oxide) (PEO) ratio and PEO molecular weight (MW) were evaluated by 33 factorial design using Design of Experiment (DOE). The electrospinning process parameters were optimized to obtain a balance between high elastic modulus and small fiber diameter. The model predicted optimized conditions were 50 kV m-1 electric field, 95/5 lignin-to-PEO ratio and 1000 kDa MW of PEO. When compared to KLA, Bio-KLA CFs showed a 2.7-fold increase in elastic modulus, 2-fold increase in tensile strength and 30% decrease in fiber diameter under the same optimum conditions. The results clearly show that bio-cleaning improved the mechanical properties of lignin derived CF.

13.
Cell ; 178(2): 330-345.e22, 2019 07 11.
Artículo en Inglés | MEDLINE | ID: mdl-31257027

RESUMEN

For tumors to progress efficiently, cancer cells must overcome barriers of oxidative stress. Although dietary antioxidant supplementation or activation of endogenous antioxidants by NRF2 reduces oxidative stress and promotes early lung tumor progression, little is known about its effect on lung cancer metastasis. Here, we show that long-term supplementation with the antioxidants N-acetylcysteine and vitamin E promotes KRAS-driven lung cancer metastasis. The antioxidants stimulate metastasis by reducing levels of free heme and stabilizing the transcription factor BACH1. BACH1 activates transcription of Hexokinase 2 and Gapdh and increases glucose uptake, glycolysis rates, and lactate secretion, thereby stimulating glycolysis-dependent metastasis of mouse and human lung cancer cells. Targeting BACH1 normalized glycolysis and prevented antioxidant-induced metastasis, while increasing endogenous BACH1 expression stimulated glycolysis and promoted metastasis, also in the absence of antioxidants. We conclude that BACH1 stimulates glycolysis-dependent lung cancer metastasis and that BACH1 is activated under conditions of reduced oxidative stress.


Asunto(s)
Antioxidantes/farmacología , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/metabolismo , Glucólisis/efectos de los fármacos , Neoplasias Pulmonares/patología , Animales , Antioxidantes/administración & dosificación , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Movimiento Celular/efectos de los fármacos , Gliceraldehído-3-Fosfato Deshidrogenasa (Fosforilante)/metabolismo , Hemo/metabolismo , Hexoquinasa/antagonistas & inhibidores , Hexoquinasa/genética , Hexoquinasa/metabolismo , Humanos , Estimación de Kaplan-Meier , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/mortalidad , Ratones , Ratones Endogámicos NOD , Ratones Noqueados , Ratones SCID , Factor 2 Relacionado con NF-E2/metabolismo , Metástasis de la Neoplasia , Interferencia de ARN , ARN Interferente Pequeño/metabolismo , Especies Reactivas de Oxígeno/metabolismo
14.
Soft Matter ; 15(27): 5400-5411, 2019 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-31172158

RESUMEN

Two colonies of Bacillus subtilis of identical strains growing adjacent to each other on an agar plate exhibit two distinct types of interactions: they either merge as they grow or demarcation occurs leading to formation of a line of demarcation at the colony fronts. The nature of this interaction depends on the agar concentration in the growth medium and the initial separation between the colonies. When the agar concentration was 0.67% or lower, the two sibling colonies were found to always merge. At 1% or higher concentrations, the colonies formed a demarcation line only when their initial separation was 20 mm or higher. Interactions of a colony with solid structures and liquid drops have indicated that biochemical factors rather than the presence of physical obstacles are responsible for the demarcation line formation. A reaction diffusion model has been formulated to predict if two sibling colonies will form a demarcation line under given agar concentration and initial separation. The model prediction agrees well with experimental findings and generates a dimensionless phase diagram containing merging and demarcation regimes. The phase diagram is in terms of a dimensionless initial separation, d[combining macron], and a dimensionless diffusion coefficient, D[combining macron], of the colonies. The phase boundary between the two interaction regimes can be described by a power law relation between d[combining macron] and D[combining macron].


Asunto(s)
Agar/química , Bacillus subtilis/fisiología , Bacillus subtilis/clasificación , Técnicas Bacteriológicas , Medios de Cultivo , Difusión , Modelos Biológicos , Movimiento
15.
PLoS One ; 14(1): e0210339, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30699142

RESUMEN

The bacterium Sporosarcina pasteurii (SP) is known for its ability to cause the phenomenon of microbially induced calcium carbonate precipitation (MICP). We explored bacterial participation in the initial stages of the MICP process at the cellular length scale under two different growth environments (a) liquid culture (b) MICP in a soft agar (0.5%) column. In the liquid culture, ex-situ imaging of the cellular environment indicated that S. pasteurii was facilitating nucleation of nanoscale crystals of calcium carbonate on bacterial cell surface and its growth via ureolysis. During the same period, the meso-scale environment (bulk medium) was found to have overgrown calcium carbonate crystals. The effect of media components (urea, CaCl2), presence of live and dead in the growth medium were explored. The agar column method allows for in-situ visualization of the phenomena, and using this platform, we found conclusive evidence of the bacterial cell surface facilitating formation of nanoscale crystals in the microenvironment. Here also the bulk environment or the meso-scale environment was found to possess overgrown calcium carbonate crystals. Extensive elemental analysis using Energy dispersive X-ray spectroscopy (EDS) and X-ray powder diffraction (XRD), confirmed that the crystals to be calcium carbonate, and two different polymorphs (calcite and vaterite) were identified. Active participation of S. pasteurii cell surface as the site of calcium carbonate precipitation has been shown using EDS elemental mapping with Scanning transmission electron microscopy (STEM) and scanning electron microscopy (SEM).


Asunto(s)
Carbonato de Calcio/química , Carbonato de Calcio/metabolismo , Sporosarcina/metabolismo , Sporosarcina/ultraestructura , Biomineralización , Membrana Celular/química , Membrana Celular/metabolismo , Membrana Celular/ultraestructura , Cristalización , Medios de Cultivo , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión de Rastreo , Nanoestructuras/química , Nanoestructuras/ultraestructura , Difracción de Polvo , Espectrometría por Rayos X , Sporosarcina/crecimiento & desarrollo
16.
J Biol Chem ; 294(12): 4381-4400, 2019 03 22.
Artículo en Inglés | MEDLINE | ID: mdl-30679313

RESUMEN

MicroRNAs of the miR-16 and miR-34 families have been reported to inhibit cell cycle progression, and their loss has been linked to oncogenic transformation. Utilizing a high-throughput, genome-wide screen for miRNAs and mRNAs that are differentially regulated in osteosarcoma (OS) cell lines, we report that miR-449a and miR-424, belonging to the miR-34 and miR-16 families, respectively, target the major S/G2 phase cyclin, cyclin A2 (CCNA2), in a bipartite manner. We found that the 3'-UTR of CCNA2 is recognized by miR-449a, whereas the CCNA2 coding region is targeted by miR-424. Of note, we observed loss of both miR-449a and miR-424 in OS, resulting in derepression of CCNA2 and appearance of aggressive cancer phenotypes. Ectopic expression of miR-449a and miR-424 significantly decreased cyclin A2 levels and inhibited proliferation rate, migratory potential, and colony-forming ability of OS cells. To further probe the roles of miR-449a and miR-424 in OS, we developed an OS mouse model by intraosseous injection of U2OS cells into the tibia bone of NOD-scid mice, which indicated that miR-449a and miR-424 co-expression suppresses tumor growth. On the basis of this discovery, we analyzed the gene expression of human OS biopsy samples, revealing that miR-449a and miR-424 are both down-regulated, whereas cyclin A2 is significantly up-regulated in these OS samples. In summary, the findings in our study highlight that cyclin A2 repression by miRNAs of the miR-16 and miR-34 families is lost in aggressive OS.


Asunto(s)
Neoplasias Óseas/genética , Ciclina A2/metabolismo , MicroARNs/fisiología , Osteosarcoma/genética , Regiones no Traducidas 3' , Animales , Neoplasias Óseas/metabolismo , Neoplasias Óseas/patología , Línea Celular , Línea Celular Tumoral , Proliferación Celular , Replicación del ADN , Modelos Animales de Enfermedad , Regulación hacia Abajo , Fase G1 , Fase G2 , Redes Reguladoras de Genes , Humanos , Ratones , Ratones Endogámicos NOD , Ratones SCID , MicroARNs/genética , Osteosarcoma/metabolismo , Osteosarcoma/patología , ARN Mensajero/genética , Fase S
17.
Sci Rep ; 8(1): 784, 2018 01 15.
Artículo en Inglés | MEDLINE | ID: mdl-29335585

RESUMEN

The development of nano-enabled composite materials has led to a paradigm shift in the manufacture of high-performance nanocomposite membranes with enhanced permeation, thermo-mechanical, and antibacterial properties. The major challenges to the successful incorporation of nanoparticles (NPs) to polymer films are the severe aggregation of the NPs and the weak compatibility of NPs with polymers. These two phenomena lead to the formation of non-selective voids at the interface of the polymer and NPs, which adversely affect the separation performance of the membrane. To overcome these challenges, we have developed a new method for the fabrication of robust TFN reverse osmosis membranes. This approach relies on the simultaneous synthesis and surface functionalization of TiO2 NPs in an organic solvent (heptane) via biphasic solvothermal reaction. The resulting stable suspension of the TiO2 NPs in heptane was then utilized in the interfacial (in-situ) polymerization reaction where the NPs were entrapped within the matrix of the polyamide (PA) membrane. TiO2 NPs of 10 nm were effectively incorporated into the thin PA layer and improved the thermal stability and anti-biofouling properties of the resulting TFN membranes. These features make our synthesized membranes potential candidates for applications where the treatment of high-temperature streams containing biomaterials is desirable.


Asunto(s)
Incrustaciones Biológicas/prevención & control , Nanopartículas del Metal/química , Polímeros/química , Titanio/química , Antibacterianos/química , Antibacterianos/farmacología , Escherichia coli/efectos de los fármacos , Nanopartículas del Metal/toxicidad , Microscopía Electrónica de Rastreo , Tamaño de la Partícula , Temperatura , Rayos Ultravioleta
18.
Mol Cell Biol ; 38(2)2018 01 15.
Artículo en Inglés | MEDLINE | ID: mdl-29061732

RESUMEN

The migration of chromosomes during mitosis is mediated primarily by kinesins that bind to the chromosomes and move along the microtubules, exerting pulling and pushing forces on the centrosomes. We report that a DNA replication protein, Sld5, localizes to the centrosomes, resisting the microtubular pulling forces experienced during chromosome congression. In the absence of Sld5, centriolar satellites, which normally cluster around the centrosomes, are dissipated throughout the cytoplasm, resulting in the loss of their known function of recruiting the centrosomal protein, pericentrin. We observed that Sld5-deficient centrosomes lacking pericentrin were unable to endure the CENP-E- and Kid-mediated microtubular forces that converge on the centrosomes during chromosome congression, resulting in monocentriolar and acentriolar spindle poles. The minus-end-directed kinesin-14 motor protein, HSET, sustains the traction forces that mediate centrosomal fragmentation in Sld5-depleted cells. Thus, we report that a DNA replication protein has an as yet unknown function of ensuring spindle pole resistance to traction forces exerted during chromosome congression.


Asunto(s)
Centriolos/metabolismo , Centrosoma/fisiología , Proteínas Cromosómicas no Histona/metabolismo , Miembro 3 de la Subfamilia B de Transportadores de Casetes de Unión a ATP/genética , Miembro 3 de la Subfamilia B de Transportadores de Casetes de Unión a ATP/metabolismo , Autoantígenos/genética , Autoantígenos/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Centriolos/genética , Centrosoma/química , Proteínas Cromosómicas no Histona/genética , Cromosomas Humanos/metabolismo , Daño del ADN , Células HeLa , Humanos , Interfase/fisiología , Microtúbulos/química , Microtúbulos/fisiología , Mitosis , Polos del Huso/fisiología , Polos del Huso/ultraestructura , Imagen de Lapso de Tiempo
19.
Sensors (Basel) ; 17(11)2017 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-29099804

RESUMEN

Conventional ion-selective electrodes with a liquid junction have the disadvantage of potential drift. All-solid-state ion-selective electrodes with solid contact in between the metal electrode and the ion-selective membrane offer high capacitance or conductance to enhance potential stability. Solution-casted chitosan/Prussian blue nanocomposite (ChPBN) was employed as the solid contact layer for an all-solid-state sodium ion-selective electrode in a potentiometric sodium ion sensor. Morphological and chemical analyses confirmed that the ChPBN is a macroporous network of chitosan that contains abundant Prussian blue nanoparticles. Situated between a screen-printed carbon electrode and a sodium-ionophore-filled polyvinylchloride ion-selective membrane, the ChPBN layer exhibited high redox capacitance and fast charge transfer capability, which significantly enhanced the performance of the sodium ion-selective electrode. A good Nernstian response with a slope of 52.4 mV/decade in the linear range from 10-4-1 M of NaCl was observed. The stability of the electrical potential of the new solid contact was tested by chronopotentiometry, and the capacitance of the electrode was 154 ± 4 µF. The response stability in terms of potential drift was excellent (1.3 µV/h) for 20 h of continuous measurement. The ChPBN proved to be an efficient solid contact to enhance the potential stability of the all-solid-state ion-selective electrode.

20.
J Biol Chem ; 292(52): 21264-21281, 2017 12 29.
Artículo en Inglés | MEDLINE | ID: mdl-29109143

RESUMEN

The tumor microenvironment is characterized by nutrient-deprived conditions in which the cancer cells have to adapt for survival. Serum starvation resembles the growth factor deprivation characteristic of the poorly vascularized tumor microenvironment and has aided in the discovery of key growth regulatory genes and microRNAs (miRNAs) that have a role in the oncogenic transformation. We report here that miR-874 down-regulates the major G1/S phase cyclin, cyclin E1 (CCNE1), during serum starvation. Because the adaptation of cancer cells to the tumor microenvironment is vital for subsequent oncogenesis, we tested for miR-874 and CCNE1 interdependence in osteosarcoma cells. We observed that miR-874 inhibits CCNE1 expression in primary osteoblasts, but in aggressive osteosarcomas, miR-874 is down-regulated, leading to elevated CCNE1 expression and appearance of cancer-associated phenotypes. We established that loss of miR-874-mediated control of cyclin E1 is a general feature of osteosarcomas. The down-regulation of CCNE1 by miR-874 is independent of E2F transcription factors. Restoration of miR-874 expression impeded S phase progression, suppressing aggressive growth phenotypes, such as cell invasion, migration, and xenograft tumors, in nude mice. In summary, we report that miR-874 inhibits CCNE1 expression during growth factor deprivation and that miR-874 down-regulation in osteosarcomas leads to CCNE1 up-regulation and more aggressive growth phenotypes.


Asunto(s)
Ciclina E/fisiología , MicroARNs/fisiología , Proteínas Oncogénicas/fisiología , Osteosarcoma/metabolismo , Animales , Línea Celular Tumoral , Proliferación Celular , Transformación Celular Neoplásica/genética , Ciclina E/genética , Ciclina G1/metabolismo , Regulación hacia Abajo , Puntos de Control de la Fase G1 del Ciclo Celular/genética , Puntos de Control de la Fase G1 del Ciclo Celular/fisiología , Regulación Neoplásica de la Expresión Génica/genética , Humanos , Ratones , Ratones Desnudos , MicroARNs/genética , MicroARNs/metabolismo , Proteínas Oncogénicas/genética , Oncogenes , Osteosarcoma/genética , Fase S
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