1,173 research outputs found
Development and Evaluation of Praziquantel Solid Dispersions in Sodium Starch Glycolate
Purpose: To develop and characterize solid dispersions of praziquantel (PZQ) with sodium starch glycolate (SSG) for enhanced drug solubility.Methods: PZQ solid dispersion (SD) was prepared using co-precipitation method by solvent evaporation. The ratios of PZQ to SSG were 2:1, 1:1, 1:2, 1:3 (w/w). PZQ solubility was evaluated in purified water, and PZQ dissolution test was carried out in 0.1N HCl. Structural characterization of the dispersions was accomplished by x-ray diffraction (XRD) and infrared spe ctroscopy (FTIR) while the external morphology of the SDs, SSG and PZQ were studied by scanning electron microscopy (SEM). Mucoadhesion properties of the SD (1:3) and SSG, on mucin disks were examined using texture profile analysis.Results: The highest solubility was obtained with 1:3 solid dispersion, with PZQ solubility of 97.31 %, which is 3.65-fold greater than the solubility of pure PZQ and physical misture (PM, 1:3). XRD results indicate a reduction in PZQ crystallinity while infrared spectra showed that the functional groups of PZQ and SSG were preserved. SEM showed that the physical structure of PZQ was modified from crystalline to amorphous. The amount of PZQ in PM and SD (1:3) that dissolved in 60 min was 70 and 88 %, respectively, and these values increased to 76 and 96 %, respectively. The solid dispersion reduced the mucoadhesive property of the glycolate.Conclusion: Solid dispersion formulation using SSG is a good alternative approach for increasing the dissolution rate of PZQ.Keywords: Praziquantel, Drug bioavailability, Schistosomiasis, Solid dispersion, Co-precipitation, Sodium starch glycolat
The Local Bias Model in the Large Scale Halo Distribution
We explore the biasing in the clustering statistics of halos as compared to
dark matter (DM) in simulations. We look at the second and third order
statistics at large scales of the (intermediate) MICEL1536 simulation and also
measure directly the local bias relation h = f({\delta}) between DM
fluctuations, {\delta}, smoothed over a top-hat radius Rs at a point in the
simulation and its corresponding tracer h (i.e. halos) at the same point. This
local relation can be Taylor expanded to define a linear (b1) and non-linear
(b2) bias parameters. The values of b1 and b2 in the simulation vary with Rs
approaching a constant value around Rs > 30 - 60 Mpc/h. We use the local
relation to predict the clustering of the tracer in terms of the one of DM.
This prediction works very well (about percent level) for the halo 2-point
correlation {\xi}(r_12) for r_12 > 15 Mpc/h, but only when we use the biasing
values that we found at very large smoothing radius Rs > 30 - 60 Mpc/h. We find
no effect from stochastic or next to leading order terms in the f({\delta})
expansion. But we do find some discrepancies in the 3-point function that needs
further understanding. We also look at the clustering of the smoothed moments,
the variance and skewness which are volume average correlations and therefore
include clustering from smaller scales. In this case, we find that both next to
leading order and discreetness corrections (to the local model) are needed at
the 10 - 20% level. Shot-noise can be corrected with a term {\sigma}e^2/n where
{\sigma}e^2 < 1, i.e., always smaller than the Poisson correction. We also
compare these results with the peak-background split predictions from the
measured halo mass function. We find 5-10% systematic (and similar statistical)
errors in the mass estimation when we use the halo model biasing predictions to
calibrate the mass.Comment: Accepted in MNRAS. Compared to first version, the paper has been
completely reorganised. New figures and content adde
Pseudoboehmite as a drug delivery system for acyclovir
Herpes simplex virus is among the most prevalent sexually transmitted infections. Acyclovir is a potent, selective inhibitor of herpes viruses and it is indicated for the treatment and management of recurrent cold sores on the lips and face, genital herpes, among other diseases. The problem of the oral bioavailability of acyclovir is limited because of the low permeability across the gastrointestinal membrane. The use of nanoparticles of pseudoboehmite as a drug delivery system in vitro assays is a promising approach to further the permeability of acyclovir release. Here we report the synthesis of high purity pseudoboehmite from aluminium nitrate and ammonium hydroxide containing nanoparticles, using the sol–gel method, as a drug delivery system to improve the systemic bioavailability of acyclovir. The presence of pseudoboehmite nanoparticles were verified by infrared spectroscopy, transmission electron microscopy, and X-ray diffraction techniques. In vivo tests were performed with Wistar rats to compare the release of acyclovir, with and without the addition of pseudoboehmite. The administration of acyclovir with the addition of pseudoboehmite increased the drug content by 4.6 times in the plasma of Wistar rats after 4 h administration. We determined that the toxicity of pseudoboehmite is low up to 10 mg/mL, in gel and the dried pseudoboehmite nanoparticles.The authors thank the Mackenzie Presbyterian University, Texas Tech University, Mack Pesquisa, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES), Cnpq, and FAPESP (grant 2010/19157-9 and grant 2017/22396-4) for the sponsorship to this project
Fitting the incidence data from the city of Campinas, Brazil, based on dengue transmission modellings considering time-dependent entomological parameters
FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFour time-dependent dengue transmission models are considered in order to fit the incidence data from the City of Campinas, Brazil, recorded from October 1st 1995 to September 30th 2012. The entomological parameters are allowed to depend on temperature and precipitation, while the carrying capacity and the hatching of eggs depend only on precipitation. The whole period of incidence of dengue is split into four periods, due to the fact that the model is formulated considering the circulation of only one serotype. Dengue transmission parameters from human to mosquito and mosquito to human are fitted for each one of the periods. The time varying partial and overall effective reproduction numbers are obtained to explain the incidence of dengue provided by the models.Four time-dependent dengue transmission models are considered in order to fit the incidence data from the City of Campinas, Brazil, recorded from October 1st 1995 to September 30th 2012. The entomological parameters are allowed to depend on temperature and precipitation, while the carrying capacity and the hatching of eggs depend only on precipitation. The whole period of incidence of dengue is split into four periods, due to the fact that the model is formulated considering the circulation of only one serotype. Dengue transmission parameters from human to mosquito and mosquito to human are fitted for each one of the periods. The time varying partial and overall effective reproduction numbers are obtained to explain the incidence of dengue provided by the models113FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO2009/15098-
Two rapid assays for screening of patulin biodegradation
Artículo sobre distintos ensayos para comprobar la biodegradación de la patulinaThe mycotoxin patulin is produced by the blue
mould pathogen Penicillium expansum in rotting apples
during postharvest storage. Patulin is toxic to a wide range
of organisms, including humans, animals, fungi and bacteria.
Wash water from apple packing and processing
houses often harbours patulin and fungal spores, which can
contaminate the environment. Ubiquitous epiphytic yeasts,
such as Rhodosporidium kratochvilovae strain LS11 which
is a biocontrol agent of P. expansum in apples, have the
capacity to resist the toxicity of patulin and to biodegrade
it. Two non-toxic products are formed. One is desoxypatulinic
acid. The aim of the work was to develop rapid,
high-throughput bioassays for monitoring patulin degradation
in multiple samples. Escherichia coli was highly
sensitive to patulin, but insensitive to desoxypatulinic acid.
This was utilized to develop a detection test for patulin,
replacing time-consuming thin layer chromatography or
high-performance liquid chromatography. Two assays for patulin degradation were developed, one in liquid medium
and the other in semi-solid medium. Both assays allow the
contemporary screening of a large number of samples. The
liquid medium assay utilizes 96-well microtiter plates and
was optimized for using a minimum of patulin. The semisolid
medium assay has the added advantage of slowing
down the biodegradation, which allows the study and isolation
of transient degradation products. The two assays are
complementary and have several areas of utilization, from
screening a bank of microorganisms for biodegradation
ability to the study of biodegradation pathways
Geometrical tests of cosmological models. III. The cosmology-evolution diagram at z=1
The rotational velocity of distant galaxies, when interpreted as a size
(luminosity) indicator, may be used as a tool to select high redshift standard
rods (candles) and probe world models and galaxy evolution via the classical
angular diameter-redshift or Hubble diagram tests. We implement the proposed
testing strategy using a sample of 30 rotators spanning the redshift range
0.2<z<1 with high resolution spectra and images obtained by the VIMOS/VLT Deep
Redshift Survey (VVDS) and the Great Observatories Origins Deep Survey (GOODs).
We show that by applying at the same time the angular diameter-redshift and
Hubble diagrams to the same sample of objects (i.e. velocity selected galactic
discs) one can derive a characteristic chart, the cosmology-evolution diagram,
mapping the relation between global cosmological parameters and local
structural parameters of discs such as size and luminosity. This chart allows
to put constraints on cosmological parameters when general prior information
about discs evolution is available. In particular, by assuming that equally
rotating large discs cannot be less luminous at z=1 than at present (M(z=1) <
M(0)), we find that a flat matter dominated cosmology (Omega_m=1) is excluded
at a confidence level of 2sigma and an open cosmology with low mass density
(Omega_m = 0.3) and no dark energy contribution is excluded at a confidence
level greater than 1 sigma. Inversely, by assuming prior knowledge about the
cosmological model, the cosmology-evolution diagram can be used to gain useful
insights about the redshift evolution of the structural parameters of baryonic
discs hosted in dark matter halos of nearly equal masses.Comment: 14 pages and 11 figures. A&A in pres
Probing the cosmic microwave background temperature using the Sunyaev-Zeldovich effect
We discuss the possibility to constrain the relation between redshift and
temperature of the cosmic microwave background (CMB) using multifrequency
Sunyaev-Zeldovich (SZ) observations. We have simulated a catalog of clusters of
galaxies detected through their SZ signature assuming the sensitivities that
will be achieved by the {\it Planck} satellite at 100, 143 and 353 GHz, taking
into account the instrumental noise and the contamination from the Cosmic
Infrared Background and from unresolved radiosources. We have parametrized the
cosmological temperature-redshift law as . Using two
sets of SZ flux density ratios (100/143 GHz, which is most sensitive to the
parametrization of the law, and 143/353 GHz, which is most sensitive to
the peculiar velocities of the clusters) we show that it is possible to recover
the law assuming that the temperatures and redshifts of the clusters are
known. From a simulated catalog of clusters, the parameter can
be recovered to an accuracy of 10. Sensitive SZ observations thus appear
as a potentially useful tool to test the standard law. Most cosmological models
predict a linear variation of the CMB temperature with redshift. The discovery
of an alternative law would have profound implications on the cosmological
model, implying creation of energy in a manner that would still maintain the
black-body shape of the CMB spectrum at redshift zero.Comment: 8 pages, 9 figures, submitted to A&
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