31,479 research outputs found
Hollow Fiber Bioreactors for In Vivo-like Mammalian Tissue Culture
Tissue culture has been used for over 100 years to study cells and responses ex vivo. The convention of this technique is the growth of anchorage dependent cells on the 2-dimensional surface of tissue culture plastic. More recently, there is a growing body of data demonstrating more in vivo-like behaviors of cells grown in 3-dimensional culture systems. This manuscript describes in detail the set-up and operation of a hollow fiber bioreactor system for the in vivo-like culture of mammalian cells. The hollow fiber bioreactor system delivers media to the cells in a manner akin to the delivery of blood through the capillary networks in vivo. The system is designed to fit onto the shelf of a standard CO2 incubator and is simple enough to be set-up by any competent cell biologist with a good understanding of aseptic technique. The systems utility is demonstrated by culturing the hepatocarcinoma cell line HepG2/C3A for 7 days. Further to this and in line with other published reports on the functionality of cells grown in 3-dimensional culture systems the cells are shown to possess increased albumin production (an important hepatic function) when compared to standard 2-dimensional tissue culture
Asymptotic Regge Trajectories of Non-strange Mesons
We analyze the asymptotic behavior of Regge trajectories of non-strange
mesons. In contrast to an existing belief, it is demonstrated that for the
asymptotically linear Regge trajectories the width of heavy hadrons cannot
linearly depend on their mass. Using the data on masses and widths of rho_J,
omega_J, a_J and f_J mesons for the spin values J \leq 6, we extract the
parameters of the asymptotically linear Regge trajectory predicted by the
finite width model of quark gluon bags. As it is shown the obtained parameters
for the data set B correspond to the cross-over temperature lying in the
interval 170.9-175.3 MeV which is consistent with the kinetic freeze-out
temperature of early hadronizing particles found in relativistic heavy ion
collisions at and above the highest SPS energy.Comment: 14 pages, 3 figure
Risk factors for wound infection in surgery for spinal metastasis
Wound infection rates are generally higher in patients undergoing surgery for spinal metastasis. Risk factors of wound infection in these patients are poorly understood.
Purpose
To identify demographic and clinical variables that may be associated with patients experiencing a higher wound infection rate.
Study design
Retrospective study with prospectively collected data of spinal metastasis patients operated consecutively at a University Teaching Hospital, adult spine division which is a tertiary referral centre for complex spinal surgery.
Patient sample
Ninety-eight patients were all surgically treated, consecutively from January 2009 to September 2011. Three patients had to be excluded due to inadequate data.
Outcome measures
Physiological measures, with presence or absence of microbiologically proven infection.
Methods
Various demographic and clinical data were recorded, including age, serum albumin level, blood total lymphocyte count, corticosteroid intake, Malnutrition Universal Screening Tool (MUST) score, neurological disability, skin closure material used, levels of surgery and administration of peri-operative corticosteroids. No funding was received from any sources for this study and as far as we are aware, there are no potential conflict of interest-associated biases in this study.
Results
Higher probabilities of infection were associated with low albumin level, seven or more levels of surgery, use of delayed/non-absorbable skin closure material and presence of neurological disability. Of these factors, levels of surgery were found to be statistically significant at the 5 % significance level.
Conclusion
Risk of infection is high (17.9 %) in patients undergoing surgery for spinal metastasis. Seven or more vertebral levels of surgery increase the risk of infection significantly (p < 0.05). Low albumin level and presence of neurological disability appear to show a trend towards increased risk of infection. Use of absorbable skin closure material, age, low lymphocyte count, peri-operative administration of corticosteroids and MUST score do not appear to influence the risk of infection
Hollow Fiber Bioreactors for In Vivo-like Mammalian Tissue Culture
Tissue culture has been used for over 100 years to study cells and responses ex vivo. The convention of this technique is the growth of
anchorage dependent cells on the 2-dimensional surface of tissue culture plastic. More recently, there is a growing body of data demonstrating
more in vivo-like behaviors of cells grown in 3-dimensional culture systems. This manuscript describes in detail the set-up and operation of a
hollow fiber bioreactor system for the in vivo-like culture of mammalian cells. The hollow fiber bioreactor system delivers media to the cells in
a manner akin to the delivery of blood through the capillary networks in vivo. The system is designed to fit onto the shelf of a standard CO2
incubator and is simple enough to be set-up by any competent cell biologist with a good understanding of aseptic technique. The systems utility
is demonstrated by culturing the hepatocarcinoma cell line HepG2/C3A for 7 days. Further to this and in line with other published reports on the
functionality of cells grown in 3-dimensional culture systems the cells are shown to possess increased albumin production (an important hepatic
function) when compared to standard 2-dimensional tissue culture
Thermal Evolution of the Non Supersymmetric Metastable Vacua in N=2 SU(2) SYM Softly Broken to N=1
It has been shown that four dimensional N=2 gauge theories, softly broken to
N=1 by a superpotential term, can accommodate metastable non-supersymmetric
vacua in their moduli space. We study the SU(2) theory at high temperatures in
order to determine whether a cooling universe settles in the metastable vacuum
at zero temperature. We show that the corrections to the free energy because of
the BPS dyons are such that may destroy the existence of the metastable vacuum
at high temperatures. Nevertheless we demonstrate the universe can settle in
the metastable vacuum, provided that the following two conditions are hold:
first the superpotential term is not arbitrarily small in comparison to the
strong coupling scale of the gauge theory, and second the metastable vacuum
lies in the strongly coupled region of the moduli space.Comment: 32 pages, 30 figure
Dynamic hierarchies in temporal directed networks
The outcome of interactions in many real-world systems can be often explained
by a hierarchy between the participants. Discovering hierarchy from a given
directed network can be formulated as follows: partition vertices into levels
such that, ideally, there are only forward edges, that is, edges from upper
levels to lower levels. In practice, the ideal case is impossible, so instead
we minimize some penalty function on the backward edges. One practical option
for such a penalty is agony, where the penalty depends on the severity of the
violation. In this paper we extend the definition of agony to temporal
networks. In this setup we are given a directed network with time stamped
edges, and we allow the rank assignment to vary over time. We propose 2
strategies for controlling the variation of individual ranks. In our first
variant, we penalize the fluctuation of the rankings over time by adding a
penalty directly to the optimization function. In our second variant we allow
the rank change at most once. We show that the first variant can be solved
exactly in polynomial time while the second variant is NP-hard, and in fact
inapproximable. However, we develop an iterative method, where we first fix the
change point and optimize the ranks, and then fix the ranks and optimize the
change points, and reiterate until convergence. We show empirically that the
algorithms are reasonably fast in practice, and that the obtained rankings are
sensible
Bioenergy: Biofuel production on the margins
Productive agricultural land that could otherwise be used to produce much-needed food crops is being diverted towards grain-based ethanol production in both Europe and the United States, partly in response to government legislation. An alternative is to grow cellulosic crops on so-called marginal lands. An evaluation of the potential of marginal lands in the Midwestern United States to produce biofuel while mitigating direct greenhouse gas emissions now finds that they have the capacity to produce a significant amount of biofuel energy without the initial carbon debt and indirect land-use costs associated with food-based biofuels
BASIS: High-performance bioinformatics platform for processing of large-scale mass spectrometry imaging data in chemically augmented histology
Mass Spectrometry Imaging (MSI) holds significant promise in augmenting digital histopathologic analysis by generating highly robust big data about the metabolic, lipidomic and proteomic molecular content of the samples. In the process, a vast quantity of unrefined data, that can amount to several hundred gigabytes per tissue section, is produced. Managing, analysing and interpreting this data is a significant challenge and represents a major barrier to the translational application of MSI. Existing data analysis solutions for MSI rely on a set of heterogeneous bioinformatics packages that are not scalable for the reproducible processing of large-scale (hundreds to thousands) biological sample sets. Here, we present a computational platform (pyBASIS) capable of optimized and scalable processing of MSI data for improved information recovery and comparative analysis across tissue specimens using machine learning and related pattern recognition approaches. The proposed solution also provides a means of seamlessly integrating experimental laboratory data with downstream bioinformatics interpretation/analyses, resulting in a truly integrated system for translational MSI
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