194 research outputs found
Stabilization and Anticancer Enhancing Activity of the Peptide Nisin by Cyclodextrin-Based Nanosponges against Colon and Breast Cancer Cells
The great variability of cancer types demands novel drugs with broad spectrum, this is the case of Nisin, a polycyclic antibacterial peptide that recently has been considered for prevention of cancer cells growth. As an accepted food additive, this drug would be very useful for intestinal cancers, but the peptide nature would make easier its degradation by digestion procedures. For that reason, the aim of present study to investigate the protective effect of two different β-cyclodextrin-based nanosponges (carbonyl diimidazole and pyromellitic dianhydride) and their anti-cancer enhancement effect of Nisin-Z encapsulated with against colon cancer cells (HT-29). To extend its possible use, a comparison with breast (MCF-7) cancer cell was carried out. The physicochemical properties, loading efficiency, and release kinetics of Nisin complex with nanosponges were studied. Then, tricin-SDS-PAGE electrophoresis was used to understand the effect of NSs on stability of Nisin-Z in the presence of gastric peptidase pepsin. In addition, the cytotoxicity and cell membrane damage of Nisin Z were evaluated by using the MTT and LDH assay, which was complemented via Annexin-V/ Propidium Iodide (PI) by using flowcytometry. CD-NS are able to complex Nisin-Z with an encapsulation efficiency around 90%. A protective effect of Nisin-Z complexed with CD-NSs was observed in presence of pepsin. An increase in the percentage of apoptotic cells was observed when the cancer cells were exposed to Nisin Z complexed with nanosponges. Interestingly, Nisin Z free and loaded on PMDA/CDI-NSs is more selectively toxic towards HT-29 cells than MCF-7 cancer cells. These results indicated that nanosponges might be good candidates to protect peptides and deliver drugs against intestinal cancers
Psychometric properties of an instrument of reasons for admission to university careers in health sciences
[EN] The purpose of this research was to analyze the validity and reliability of the instrument called “Reasons for Admission to Careers in Health Sciences (MICCS) (acronym in Spanish)”. The study was developed with a non-probabilistic and incidental sample of 194 students from a higher education institution in the state of Jalisco, Mexico. After reviewing the contenty validity by expert judges, an exploratory factor analysis was executed (principal components method and Varimax rotation). Seven dimensions were defined under the critery of theoretical position and inflection of the curve of sedimentation. The indexes of KMO (0.788) and Bartlett (X (990) = 2916.36, p=0.000) reported an appropriate model. Items with theoretical inconsistencies and saturations under of 0.4 were eliminated. Its internal consistency was acceptable (α=0.834). The final version of the instrument consisted of 30 items and six independent factors, showing satisfactory psychometric properties. Finally were contrasted the reasons for entering careers in medicine, nursing, nutrition and dentistry to the variables of sex, vocational orientation and type of school. It is proposed to extend the investigation of reasons for entering science careers health by using the scale in public and private institutions of higher education; In addition, it is recommended to analyze the relationship of the reasons for admission and psychosocial variables such as academic performance, lag, desertion, satisfaction and academic stress.[ES] El presente trabajo de investigaciĂłn tuvo como propĂłsito analizar la validez y confiabilidad del instrumento denominado “Motivos de Ingreso a las Carreras de Ciencias de la Salud (MICCS)”. El estudio se desarrollĂł con una muestra no probabilĂstica e incidental de 194 alumnos de una instituciĂłn de educaciĂłn superior del estado de Jalisco, MĂ©xico. DespuĂ©s de abordar la validez de contenido mediante jueces expertos, se ejecutĂł un análisis factorial exploratorio (mĂ©todo de componentes principales y rotaciĂłn Varimax) donde se definieron siete dimensiones bajo el criterio de postura teĂłrica e inflexiĂłn de la curva de sedimentaciĂłn. Los Ăndices de KMO (0.788) y Bartlett (X(990)=2916.36; p=0.000) señalaron un modelo apropiado y sin esfericidad. Los Ătems con inconsistencias teĂłricas y saturaciones menores a 0.4 fueron eliminados. Su consistencia interna general fue aceptable (α=0.834). La versiĂłn final del instrumento quedĂł conformada de 30 reactivos y seis factores independientes, mostrando propiedades psicomĂ©tricas satisfactorias. Por Ăşltimo, se contrastaron los motivos de ingreso de las carreras de medicina, enfermerĂa, nutriciĂłn y odontologĂa con las variables de sexo, orientaciĂłn vocacional y tipo de bachillerato. Se propone ampliar la lĂnea de investigaciĂłn de los motivos de ingreso a carreras de ciencias de la salud mediante el uso de la escala en instituciones de educaciĂłn superior pĂşblicas y privadas; además, se recomienda abordar la posible relaciĂłn de los motivos de ingreso con variables escolares y psicosociales como el rendimiento acadĂ©mico, el atraso educativo, la deserciĂłn, la satisfacciĂłn y el estrĂ©s acadĂ©mico.Caldera Montes, JF.; Reynoso González, O.; Sughey González Torres, Y.; Zamora Betancourt, M. (2018). Propiedades psicomĂ©tricas de un instrumento de motivos de ingreso a carreras universitarias de ciencias de la salud. 33-50. doi:10.4995/redu.2018.6052SWORD335
Coupled dark matter-dark energy in light of near Universe observations
Cosmological analysis based on currently available observations are unable to
rule out a sizeable coupling among the dark energy and dark matter fluids. We
explore a variety of coupled dark matter-dark energy models, which satisfy
cosmic microwave background constraints, in light of low redshift and near
universe observations. We illustrate the phenomenology of different classes of
dark coupling models, paying particular attention in distinguishing between
effects that appear only on the expansion history and those that appear in the
growth of structure. We find that while a broad class of dark coupling models
are effectively models where general relativity (GR) is modified --and thus can
be probed by a combination of tests for the expansion history and the growth of
structure--, there is a class of dark coupling models where gravity is still
GR, but the growth of perturbations is, in principle modified. While this
effect is small in the specific models we have considered, one should bear in
mind that an inconsistency between reconstructed expansion history and growth
may not uniquely indicate deviations from GR. Our low redshift constraints
arise from cosmic velocities, redshift space distortions and dark matter
abundance in galaxy voids. We find that current data constrain the
dimensionless coupling to be |xi|<0.2, but prospects from forthcoming data are
for a significant improvement. Future, precise measurements of the Hubble
constant, combined with high-precision constraints on the growth of structure,
could provide the key to rule out dark coupling models which survive other
tests. We shall exploit as well weak equivalence principle violation arguments,
which have the potential to highly disfavour a broad family of coupled models.Comment: 34 pages, 6 figures; changes to match published versio
The generalized second law for the interacting generalized Chaplygin gas model
We investigate the validity of the generalized second law (GSL) of
gravitational thermodynamics in a non-flat FRW universe containing the
interacting generalized Chaplygin gas with the baryonic matter. The dynamical
apparent horizon is assumed to be the boundary of the universe. We show that
for the interacting generalized Chaplygin gas as a unified candidate for dark
matter (DM) and dark energy (DE), the equation of state parameter can cross the
phantom divide. We also present that for the selected model under thermal
equilibrium with the Hawking radiation, the GSL is always satisfied throughout
the history of the universe for any spatial curvature, independently of the
equation of state of the interacting generalized Chaplygin gas model.Comment: 8 page
Interacting entropy-corrected new agegraphic dark energy in Brans-Dicke cosmology
Motivated by a recent work of one of us [1], we extend it by using quantum
(or entropy) corrected new agegraphic dark energy in the Brans-Dicke cosmology.
The correction terms are motivated from the loop quantum gravity which is one
of the competitive theories of quantum gravity. Taking the non-flat background
spacetime along with the conformal age of the universe as the length scale, we
derive the dynamical equation of state of dark energy and the deceleration
parameter. An important consequence of this study is the phantom divide
scenario with entropy-corrected new agegraphic dark energy. Moreover, we assume
a system of dark matter, radiation and dark energy, while the later interacts
only with dark matter. We obtain some essential expressions related with dark
energy dynamics. The cosmic coincidence problem is also resolved in our model.Comment: 16 pages, no figure, accepted for publication in Gen. Relativ. Gra
Large-scale instability in interacting dark energy and dark matter fluids
If dark energy interacts with dark matter, this gives a new approach to the
coincidence problem. But interacting dark energy models can suffer from
pathologies. We consider the case where the dark energy is modelled as a fluid
with constant equation of state parameter w. Non-interacting constant-w models
are well behaved in the background and in the perturbed universe. But the
combination of constant w and a simple interaction with dark matter leads to an
instability in the dark sector perturbations at early times: the curvature
perturbation blows up on super-Hubble scales. Our results underline how
important it is to carefully analyze the relativistic perturbations when
considering models of coupled dark energy. The instability that we find has
been missed in some previous work where the perturbations were not consistently
treated. The unstable mode dominates even if adiabatic initial conditions are
used. The instability also arises regardless of how weak the coupling is. This
non-adiabatic instability is different from previously discovered adiabatic
instabilities on small scales in the strong-coupling regime.Comment: 15 pages, 5 figures. New reference; published versio
Large-scale instability in interacting dark energy and dark matter fluids
If dark energy interacts with dark matter, this gives a new approach to the
coincidence problem. But interacting dark energy models can suffer from
pathologies. We consider the case where the dark energy is modelled as a fluid
with constant equation of state parameter w. Non-interacting constant-w models
are well behaved in the background and in the perturbed universe. But the
combination of constant w and a simple interaction with dark matter leads to an
instability in the dark sector perturbations at early times: the curvature
perturbation blows up on super-Hubble scales. Our results underline how
important it is to carefully analyze the relativistic perturbations when
considering models of coupled dark energy. The instability that we find has
been missed in some previous work where the perturbations were not consistently
treated. The unstable mode dominates even if adiabatic initial conditions are
used. The instability also arises regardless of how weak the coupling is. This
non-adiabatic instability is different from previously discovered adiabatic
instabilities on small scales in the strong-coupling regime.Comment: 15 pages, 5 figures. New reference; published versio
Notes on interacting holographic dark energy model in a closed universe
We consider interacting holographic dark energy model in Friedmann Robertson
Walker space time with positive spatial curvature and investigate the behavior
of curvature parameter and dark energy density in accelerated expanding epoch.
We also derive some conditions needed to cross the phantom divide line in this
model.Comment: 10 pages, typos corrected, some explanations and references added and
updated, accepted for publication in JCA
REST Controls Self-Renewal and Tumorigenic Competence of Human Glioblastoma Cells
The Repressor Element 1 Silencing Transcription factor (REST/NRSF) is a master repressor of neuronal programs in non-neuronal lineages shown to function as a central regulator of developmental programs and stem cell physiology. Aberrant REST function has been associated with a number of pathological conditions. In cancer biology, REST has been shown to play a tumor suppressor activity in epithelial cancers but an oncogenic role in brain childhood malignancies such as neuroblastoma and medulloblastoma. Here we examined REST expression in human glioblastoma multiforme (GBM) specimens and its role in GBM cells carrying self-renewal and tumorigenic competence. We found REST to be expressed in GBM specimens, its presence being particularly enriched in tumor cells in the perivascular compartment. Significantly, REST is highly expressed in self-renewing tumorigenic-competent GBM cells and its knock down strongly reduces their self-renewal in vitro and tumor-initiating capacity in vivo and affects levels of miR-124 and its downstream targets. These results indicate that REST contributes to GBM maintenance by affecting its self-renewing and tumorigenic cellular component and that, hence, a better understanding of these circuitries in these cells might lead to new exploitable therapeutic targets
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