1,378 research outputs found
Chitosan as an antimicrobial agent for footwear leather components
In the footwear industry, microorganisms’ growth can pose problems of material deterioration with associated unpleasant smell and generate possible infections in susceptible individuals. Generally, footwear presents high relative humidity conditions that enable the growth of bacteria and fungi. Additionally, leather itself and some tannery agents such as oils and greases, provide a substrate where microorganisms can grow. In the foot, microtraumas caused by ingrown nails, abrasions and lacerations can allow microbial invasion through epidermis, resulting in skin infection.
In this work, the applicability of chitosan functional coatings to leather was tested, with the purpose to develop new base materials to produce footwear components. The leather treated with chitosan was then studied for its antibacterial properties against 3 different bacteria.COMPETE, QREN and EU (project QREN-ADI-1585-ADVANCEDSHOE)
Liposomes as a nanoplatform to improve the delivery of antibiotics into Staphylococcus aureus biofilms
Research Areas: Pharmacology & PharmacyABSTRACT - Staphylococcus aureus biofilm-associated infections are a major public health concern. Current therapies are hampered by reduced penetration of antibiotics through biofilm and low accumulation levels at infected sites, requiring prolonged usage. To overcome these, repurposing antibiotics
in combination with nanotechnological platforms is one of the most appealing fast-track and costeffective approaches. In the present work, we assessed the potential therapeutic benefit of three
antibiotics, vancomycin, levofloxacin and rifabutin (RFB), through their incorporation in liposomes.
Free RFB displayed the utmost antibacterial effect with MIC and MBIC50 below 0.006 µg/mL towards
a methicillin susceptible S. aureus (MSSA). RFB was selected for further in vitro studies and the
influence of different lipid compositions on bacterial biofilm interactions was evaluated. Although
positively charged RFB liposomes displayed the highest interaction with MSSA biofilms, RFB incorporated in negatively charged liposomes displayed lower MBIC50 values in comparison to the
antibiotic in the free form. Preliminary safety assessment on all RFB formulations towards osteoblast
and fibroblast cell lines demonstrated that a reduction on cell viability was only observed for the
positively charged liposomes. Overall, negatively charged RFB liposomes are a promising approach
against biofilm S. aureus infections and further in vivo studies should be performed.info:eu-repo/semantics/publishedVersio
Drought-induced embolism in current-year shoots of two Mediterranean evergreen oaks
threatened
by the increasing water deficits related to climate change. To contribute to the understanding of
the capacity of these oaks to withstand severe drought we assessed the vulnerability to xylem embolism
and the anatomical traits in current-year shoots. Data were collected in mature trees at two sites, in central/
coastal and southern/inland Portugal. In situ safety margins to hydraulic failure were evaluated from
long-term predawn and midday leaf water potential records. Results showed that xylem vulnerability to
embolism was similar in Q. ilex and Q. suber. The 50% loss in hydraulic conductivity (Wxyl,50PLC) was
observed at xylem water potentials of 2.9 and 3.2 MPa in shoots of Q. suber and Q. ilex, respectively.
Values of mean vessel diameter of Q. suber shoots at both sites suggest an intra-species adaptation to
the local water availability, with larger vessels at the more mesic site. In situ hydraulic safety margins
observed in shoots showed that, even during the driest periods, both oaks lived comfortably above the
most critical embolism thresholds. However, the hydraulic safety margins were narrower in the driest
site. Results are relevant to the understanding of survival, growth, and functional behaviour of evergreen
oaks in Mediterranean climates, under recurrent/seasonal drought condition
Chromosomal, epigenetic and microRNA-mediated inactivation of LRP1B, a modulator of the extracellular environment of thyroid cancer cells
The low-density lipoprotein receptor-related protein (LRP1B), encoding an endocytic LDL-family receptor, is among the 10 most significantly deleted genes across 3312 human cancer specimens. However, currently the apparently crucial role of this lipoprotein receptor in carcinogenesis is not clear. Here we show that LRP1B inactivation (by chromosomal, epigenetic and microRNA (miR)-mediated mechanisms) results in changes to the tumor environment that confer cancer cells an increased growth and invasive capacity. LRP1B displays frequent DNA copy number loss and CpG island methylation, resulting in mRNA underexpression. By using CpG island reporters methylated in vitro, we found that DNA methylation disrupts a functional binding site for the histone-acetyltransferase p300 located at intron 1. We identified and validated an miR targeting LRP1B (miR-548a-5p), which is overexpressed in cancer cell lines as a result of 8q22 DNA gains. Restoration of LRP1B impaired in vitro and in vivo tumor growth, inhibited cell invasion and led to a reduction of matrix metalloproteinase 2 in the extracellular medium. We emphasized the role of an endocytic receptor acting as a tumor suppressor by modulating the extracellular environment composition in a way that constrains the invasive behavior of the cancer cells
Analytical results for coupled map lattices with long-range interactions
We obtain exact analytical results for lattices of maps with couplings that
decay with distance as . We analyze the effect of the coupling
range on the system dynamics through the Lyapunov spectrum. For lattices whose
elements are piecewise linear maps, we get an algebraic expression for the
Lyapunov spectrum. When the local dynamics is given by a nonlinear map, the
Lyapunov spectrum for a completely synchronized state is analytically obtained.
The critical lines characterizing the synchronization transition are determined
from the expression for the largest transversal Lyapunov exponent. In
particular, it is shown that in the thermodynamical limit, such transition is
only possible for sufficiently long-range interactions, namely, for , where is the lattice dimension.Comment: 4 pages, 2 figures, corrections included. Phys. Rev. E 68, 045202(R)
(2003); correction in pres
Biotransformation with whole microbial systems in a continuous flow reactor : resolution of (RS)-flurbiprofen using Aspergillus oryzae by direct esterification with ethanol in organic solvent
Cell-bound lipases of dry mycelium of Aspergillus oryzae were used in organic solvent for the resolution of racemic flurbiprofen by direct esterification with ethanol in a flow-chemistry reactor. Under flow conditions a significant reduction of the reaction time and an increase of the enantioselectivity were achieved compared to the batch mode. Moreover, the process was implemented by adding an in-line purification step integrated with the racemization of the unreacted flurbiprofen directly into a polymer-supported resin
Alternatives to Quintessence Model Building
We discuss the issue of toy model building for the dark energy component of
the universe. Specifically, we consider two generic toy models recently
proposed as alternatives to quintessence models, known as Cardassian expansion
and the Chaplygin gas. We show that the former is enteriely equivalent to a
class of quintessence models. We determine the observational constraints on the
latter, coming from recent supernovae results and from the shape of the matter
power spectrum. As expected, these restrict the model to a behaviour that
closely matches that of a standard cosmological constant .Comment: RevTex4; 7 pages, 4 figures. v2: Improved discussion of constraints
on Chaplygin gas models. Other clarifications added. Phys Rev. D (in press
Investigating the effects of an oral fructose challenge on hepatic ATP reserves in healthy volunteers: a 31P MRS study
Background: Impaired homeostasis of hepatic ATP has been associated with NAFLD. An intravenous fructose infusion has been shown to be an effective challenge to monitor the depletion and subsequent recovery of hepatic ATP reserves using 31P MRS.
Aims: The purpose of this study was to evaluate the effects of an oral rather than intravenous fructose challenge on hepatic ATP reserves in healthy subjects.
Methods: Self-reported healthy males were recruited. Following an overnight fast, baseline liver glycogen and lipid levels were measured using Magnetic Resonance Spectroscopy (MRS). Immediately after consuming a 500 ml 75 g fructose drink (1275 kJ) subjects were scanned continuously for 90 min to acquire dynamic 31P MRS measurements of liver ATP reserves.
Results: A significant effect on ATP reserves was observed across the time course (P < 0.05). Mean ATP levels reached a minimum at 50 min which was markedly lower than baseline (80 ± 17% baseline, P < 0.05). Subsequently, mean values tended to rise but did not reach statistical significance above minimum. The time to minimum ATP levels across subjects was negatively correlated with BMI (R2 ¼ 0.74, P < 0.005). Rates of ATP recovery were not significantly correlated with BMI or liver fat levels, but were negatively correlated with baseline glycogen levels (R2 ¼ 0.7, P < 0.05).
Conclusions: Depletion of ATP reserves can be measured non-invasively following an oral fructose challenge using 31P
Realistic Equations of State for the Primeval Universe
Early universe equations of state including realistic interactions between
constituents are built up. Under certain reasonable assumptions, these
equations are able to generate an inflationary regime prior to the
nucleosynthesis period. The resulting accelerated expansion is intense enough
to solve the flatness and horizon problems. In the cases of curvature parameter
\kappa equal to 0 or +1, the model is able to avoid the initial singularity and
offers a natural explanation for why the universe is in expansion.Comment: 32 pages, 5 figures. Citations added in this version. Accepted EPJ
- …