835 research outputs found
Calcium/calmodulin-dependent kinases can regulate the TSH expression in the rat pituitary.
PURPOSE: The endocrine secretion of TSH is a finely orchestrated process
controlled by the thyrotropin-releasing hormone (TRH). Its homeostasis and
signaling rely on many calcium-binding proteins belonging to the "EF-hand"
protein family. The Ca2+/calmodulin (CaM) complex is associated with
Ca2+/CaM-dependent kinases (Ca2+/CaMK). We have investigated Ca2+/CaMK
expression and regulation in the rat pituitary.
METHODS: The expression of CaMKII and CaMKIV in rat anterior pituitary cells was
shown by immunohistochemistry. Cultured anterior pituitary cells were stimulated
by TRH in the presence and absence of KN93, the pharmacological inhibitor of
CaMKII and CaMKIV. Western blotting was then used to measure the expression of
these kinases and of the cAMP response element-binding protein (CREB). TSH
production was measured by RIA after time-dependent stimulation with TRH. Cells
were infected with a lentiviral construct coding for CaMKIV followed by
measurement of CREB phosphorylation and TSH.
RESULTS: Our study shows that two CaM kinases, CaMKII and CaMKII, are expressed
in rat pituitary cells and their phosphorylation in response to TRH occurs at
different time points, with CaMKIV being activated earlier than CaMKII. TRH
induces CREB phosphorylation through the activity of both CaMKII and CaMKIV. The
activation of CREB increases TSH gene expression. CaMKIV induces CREB
phosphorylation while its dominant negative and KN93 exert the opposite effects.
CONCLUSION: Our data indicate that the expression of Ca2+/CaMK in rat anterior
pituitary are correlated to the role of CREB in the genetic regulation of TSH,
and that TRH stimulation activates CaMKIV, which in turn phosphorylates CREB.
This phosphorylation is linked to the production of thyrotropin
Production of Succinic Acid From Basfia succiniciproducens
Basfia succiniciproducens is a facultative anaerobic capnophilic bacterium, isolated
from rumen, that naturally produces high amounts of succinic acid by fixing CO2 and
using fumarate as final electron acceptor. This metabolic feature makes it one of the
ideal candidates for developing biotechnological industrial routes that could
eventually replace the polluting and environment unfriendly petrochemical ones
that are still main sources for the production of this value-added compound. In
fact, due to the large number of applications of succinic acid that range from the more
traditional ones as food additive or pharmaceutical intermediate to the most recent as
building block for biopolymers and bioplastic, increasing demand and market size growth
are expected in the next years. In line with a âgreen revolutionâ needed to preserve our
environment, the great challenge is the establishment of commercially viable production
processes that exploit renewable materials and in particular preferably non-food
lignocellulosic biomasses and waste products. In this review, we describe the currently
available literature concerning B. succiniciproducens since the strain was first isolated,
focusing on the different renewable materials and fermentation strategies used to improve
succinic acid production titers to date. Moreover, an insight into the metabolic engineering
approaches and the key physiological characteristics of B. succiniciproducens deduced
from the different studies are presented
Forecast indices from a ground-based microwave radiometer for operational meteorology
Abstract. Today, commercial microwave radiometer profilers (MWRPs) are robust and unattended instruments providing real-time, accurate atmospheric observations at ~ 1 min temporal resolution under nearly all weather conditions. Common commercial units operate in the 20â60 GHz frequency range and are able to retrieve profiles of temperature, vapour density, and relative humidity. Temperature and humidity profiles retrieved from MWRP data are used here to feed tools developed for processing radiosonde observations to obtain values of forecast indices (FIs) commonly used in operational meteorology. The FIs considered here include K index, total totals, KO index, Showalter index, T1 gust, fog threat, lifted index, S index (STT), Jefferson index, microburst day potential index (MDPI), Thompson index, TQ index, and CAPE (convective available potential energy). Values of FIs computed from radiosonde and MWRP-retrieved temperature and humidity profiles are compared in order to quantitatively demonstrate the level of agreement and the value of continuous FI updates. This analysis is repeated for two sites at midlatitude, the first one located at low altitude in central Europe (Lindenberg, Germany) and the second one located at high altitude in North America (Whistler, Canada). It is demonstrated that FIs computed from MWRPs well correlate with those computed from radiosondes, with the additional advantage of nearly continuous updates. The accuracy of MWRP-derived FIs is tested against radiosondes, taken as a reference, showing different performances depending upon index and environmental situation. Overall, FIs computed from MWRP retrievals agree well with radiosonde values, with correlation coefficients usually above 0.8 (with few exceptions). We conclude that MWRP retrievals can be used to produce meaningful FIs, with the advantage (with respect to radiosondes) of nearly continuous updates
Nanoparticles of Cerium Oxide Targeted to an Amyloid-Beta Antigen of Alzheimer\u27s Disease and Associated Methods
Disclosed is a composition immunologically targeted to Alzheimerâs disease (AD), the composition containing amine functionalized nanoparticles of Cerium oxide coated with polyethylene glycol and bearing an antibody specific for an amyloid-beta antigen associated with AD. The invention also includes a medication manufactured with the targeted nanoceria particles and methods of treatment by administering the targeted nanoceria particles to patients in need thereof
PyRTlib: an educational Python-based library for non-scattering atmospheric microwave radiative transfer computations
This article introduces PyRTlib, a new standalone Python package for non-scattering line-by-line microwave radiative transfer simulations. PyRTlib is a flexible and user-friendly tool for computing down- and upwelling brightness temperatures and related quantities (e.g., atmospheric absorption, optical depth, opacity, mean radiating temperature) written in Python, a language commonly used nowadays for scientific software development, especially by students and early-career scientists. PyRTlib allows for simulating observations from ground-based, airborne, and satellite microwave sensors in clear-sky and in cloudy conditions (under non-scattering Rayleigh approximation). The intention for PyRTlib is not to be a competitor to state-of-the-art atmospheric radiative transfer codes that excel in speed and/or versatility (e.g., ARTS, Atmospheric Radiative Transfer Simulator; RTTOV, Radiative Transfer for TOVS (Television Infrared Observation Satellite (TIROS) Operational Vertical Sounder)). The intention is to provide an educational tool, completely written in Python, to readily simulate atmospheric microwave radiative transfer from a variety of input profiles, including predefined climatologies, global radiosonde archives, and model reanalysis. The paper presents quick examples for the built-in modules to access popular open data archives. The paper also presents examples for computing the simulated brightness temperature for different platforms (ground-based, airborne, and satellite), using various input profiles, showing how to easily modify other relevant parameters, such as the observing angle (zenith, nadir, slant), surface emissivity, and gas absorption model. PyRTlib can be easily embedded in other Python codes needing atmospheric microwave radiative transfer (e.g., surface emissivity models and retrievals). Despite its simplicity, PyRTlib can be readily used to produce present-day scientific results, as demonstrated by two examples showing (i) an absorption model comparison and validation with ground-based radiometric observations and (ii) uncertainty propagation of spectroscopic parameters through the radiative transfer calculations following a rigorous approach. To our knowledge, the uncertainty estimate is not provided by any other currently available microwave radiative transfer code, making PyRTlib unique for this aspect in the atmospheric microwave radiative transfer code scenario.</p
Multipolar Spindle Pole Coalescence Is a Major Source of Kinetochore Mis-Attachment and Chromosome Mis-Segregation in Cancer Cells
Many cancer cells display a CIN (Chromosome Instability) phenotype, by which they exhibit high rates of chromosome loss or gain at each cell cycle. Over the years, a number of different mechanisms, including mitotic spindle multipolarity, cytokinesis failure, and merotelic kinetochore orientation, have been proposed as causes of CIN. However, a comprehensive theory of how CIN is perpetuated is still lacking. We used CIN colorectal cancer cells as a model system to investigate the possible cellular mechanism(s) underlying CIN. We found that CIN cells frequently assembled multipolar spindles in early mitosis. However, multipolar anaphase cells were very rare, and live-cell experiments showed that almost all CIN cells divided in a bipolar fashion. Moreover, fixed-cell analysis showed high frequencies of merotelically attached lagging chromosomes in bipolar anaphase CIN cells, and higher frequencies of merotelic attachments in multipolar vs. bipolar prometaphases. Finally, we found that multipolar CIN prometaphases typically possessed Îł-tubulin at all spindle poles, and that a significant fraction of bipolar metaphase/early anaphase CIN cells possessed more than one centrosome at a single spindle pole. Taken together, our data suggest a model by which merotelic kinetochore attachments can easily be established in multipolar prometaphases. Most of these multipolar prometaphase cells would then bi-polarize before anaphase onset, and the residual merotelic attachments would produce chromosome mis-segregation due to anaphase lagging chromosomes. We propose this spindle pole coalescence mechanism as a major contributor to chromosome instability in cancer cells
Microbioreactor (micro-Matrix) potential in aerobic and anaerobic conditions with different industrially relevant microbial strains
Microscale fermentation systems are important high throughput tools in clone selection, and bioprocess set up and optimization, since they provide several parallel experiments in controlled conditions of pH, temperature, agitation, and gas flow rate. In this work we evaluated the performance of biotechnologically relevant strains with different respiratory requirements in the micro-Matrix microbioreactor. In particular Escherichia coli K4 requires well aerated fermentation conditions to improve its native production of chondroitin-like capsular polysaccharide, a biomedically attractive polymer. Results from batch and fed-batch experiments demonstrated high reproducibility with those obtained on 2 L reactors, although highlighting a pronounced volume loss for longer-term experiments. Basfia succiniciproducens and Actinobacillus succinogenes need CO2 addition for the production of succinic acid, a building block with several industrial applications. Different CO2 supply modes were tested for the two strains in 24 h batch experiments and results well compared with those obtained on lab-scale bioreactors. Overall, it was demonstrated that the micro-Matrix is a useful scale-down tool that is suitable for growing metabolically different strains in simple batch process, however, a series of issues should still be addressed in order to fully exploit its potential
Network Sensitivity of Systemic Risk
A growing body of studies on systemic risk in financial markets has
emphasized the key importance of taking into consideration the complex
interconnections among financial institutions. Much effort has been put in
modeling the contagion dynamics of financial shocks, and to assess the
resilience of specific financial markets - either using real network data,
reconstruction techniques or simple toy networks. Here we address the more
general problem of how shock propagation dynamics depends on the topological
details of the underlying network. To this end we consider different realistic
network topologies, all consistent with balance sheets information obtained
from real data on financial institutions. In particular, we consider networks
of varying density and with different block structures, and diversify as well
in the details of the shock propagation dynamics. We confirm that the systemic
risk properties of a financial network are extremely sensitive to its network
features. Our results can aid in the design of regulatory policies to improve
the robustness of financial markets
A statistical approach for rain intensity differentiation using Meteosat Second Generation-Spinning Enhanced Visible and InfraRed Imager observations
Abstract. This study exploits the Meteosat Second Generation (MSG)âSpinning Enhanced Visible and Infrared Imager (SEVIRI) observations to evaluate the rain class at high spatial and temporal resolutions and, to this aim, proposes the Rain Class Evaluation from Infrared and Visible observation (RainCEIV) technique. RainCEIV is composed of two modules: a cloud classification algorithm which individuates and characterizes the cloudy pixels, and a supervised classifier that delineates the rainy areas according to the three rainfall intensity classes, the non-rainy (rain rate value < 0.5 mm h-1) class, the light-to-moderate rainy class (0.5 mm hâ1 †rain rate value < 4 mm h-1), and the heavyâto-very-heavy-rainy class (rain rate value â„ 4 mm h-1). The second module considers as input the spectral and textural features of the infrared and visible SEVIRI observations for the cloudy pixels detected by the first module. It also takes the temporal differences of the brightness temperatures linked to the SEVIRI water vapour channels as indicative of the atmospheric instability strongly related to the occurrence of rainfall events. The rainfall rates used in the training phase are obtained through the Precipitation Estimation at Microwave frequencies, PEMW (an algorithm for rain rate retrievals based on Atmospheric Microwave Sounder Unit (AMSU)-B observations). RainCEIV's principal aim is that of supplying preliminary qualitative information on the rainy areas within the Mediterranean Basin where there is no radar network coverage. The results of RainCEIV have been validated against radar-derived rainfall measurements from the Italian Operational Weather Radar Network for some case studies limited to the Mediterranean area. The dichotomous assessment related to daytime (nighttime) validation shows that RainCEIV is able to detect rainy/non-rainy areas with an accuracy of about 97% (96%), and when all the rainy classes are considered, it shows a Heidke skill score of 67% (62%), a bias score of 1.36 (1.58), and a probability of detection of rainy areas of 81% (81%)
Heterogeneity, quality, and reputation in an adaptive recommendation model
Abstract.: Recommender systems help people cope with the problem of information overload. A recently proposed adaptive news recommender model [M. Medo, Y.-C. Zhang, T. Zhou, Europhys. Lett. 88, 38005 (2009)] is based on epidemic-like spreading of news in a social network. By means of agent-based simulations we study a "good get richerâ feature of the model and determine which attributes are necessary for a user to play a leading role in the network. We further investigate the filtering efficiency of the model as well as its robustness against malicious and spamming behaviour. We show that incorporating user reputation in the recommendation process can substantially improve the outcom
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