2,746 research outputs found
Stability of Feverfew and its Active Principle Parthenolide: An Elusive Antimigraine Herbal Medicine
Background
Feverfew is a traditional herbal remedy for the relief of arthritis, migraine, toothache, and menstrual difficulties. It is widely accepted that parthenolide, a sesquiterpene lactone, is its main active principle. However, the decrease of parthenolide in commercial preparations is a well-known process with no technical solution so far.
Aims
To review the evidence for the mechanism of the degradation of parthenolide and similar sesquiterpene lactones.
Methods
Systematic review.
Results and Conclusion
In conclusion, and without discarding any degradation of parthenolide into non-identifiable fragments, the fate of this compound in dry, powdered feverfew is to undergo a covalent binding to plant proteins resulting in a biologically inactive adduct - in accordance with the direct and indirect data found in the literature. This process seems to be virtually unstoppable, and temperature and light do not seem to be playing a significant role under normal storage conditions according to some authors. In the presence of a high level of humidity, parthenolide may undergo an acid-induced cyclisation giving rise to a guaianolide-type sesquiterpene lactone, a class of compound that is commonly found in Feverfew. Microbial degradations are not likely to play an important role if the formulation complies with Pharmacopoeial microbiological quality requirements. The experimental and clinical data in the literature do not report on any increase in the toxicity of stored feverfew. 
Variable stars in the globular cluster M28 (NGC 6626)
We present a new search for variable stars in the Galactic globular cluster
M28 (NGC 6626). The search is based on a series of BVI images obtained with the
SMARTS Consortium's 1.3m telescope at Cerro Tololo Inter-American Observatory,
Chile. The search was carried out using the ISIS v2.2 image subtraction
package. We find a total of 25 variable stars in the field of the cluster, 9
being new discoveries. Of the newly found variables, 1 is an ab-type RR Lyrae
star, 6 are c-type RR Lyrae, and 2 are long-period/semi-regular variables. V22,
previously classified as a type II Cepheid, appears as a bona-fide RRc in our
data. In turn, V20, previously classified as an ab-type RR Lyrae, could not be
properly phased with any reasonable period. The properties of the ab-type RR
Lyrae stars in M28 appear most consistent with an Oosterhoff-intermediate
classification, which is unusual for bona-fide Galactic globulars clusters.
However, the cluster's c-type variables do not clearly support such an
Oosterhoff type, and a hybrid Oosterhoff I/II system is accordingly another
possibility, thus raising the intriguing possibility of multiple populations
being present in M28. Coordinates, periods, and light curves in differential
fluxes are provided for all the detected variables.Comment: A&A, in pres
Evolution along the sequence of S0 Hubble types induced by dry minor mergers. II - Bulge-disk coupling in the photometric relations through merger-induced internal secular evolution
Galaxy mergers are considered as questionable mechanisms for the evolution of
lenticular galaxies (S0's), on the basis that even minor ones induce structural
changes that are difficult to reconcile with the strong bulge-disk coupling
observed in the photometric scaling relations of S0's. We check if the
evolution induced onto S0's by dry intermediate and minor mergers can reproduce
their photometric scaling relations, analysing the bulge-disk decompositions of
the merger simulations presented in Eliche-Moral et al. (2012). The mergers
induce an evolution in the photometric planes compatible with the data of S0's,
even in those ones indicating a strong bulge-disk coupling. The mergers drive
the formation of the observed photometric relation in some cases, whereas they
induce a slight dispersion compatible with data in others. Therefore, this
evolutionary mechanism tends to preserve these scaling relations. In those
photometric planes where the morphological types segregate, the mergers always
induce evolution towards the region populated by S0's. The structural coupling
of the bulge and the disk is preserved or reinforced because the mergers
trigger internal secular processes in the primary disk that induce significant
bulge growth, even although these models do not induce bars. Intermediate and
minor mergers can thus be considered as plausible mechanisms for the evolution
of S0's attending to their photometric scaling relations, as they can preserve
and even strengthen any pre-existing structural bulge-disk coupling, triggering
significant internal secular evolution (even in the absence of bars or
dissipational effects). This means that it may be difficult to isolate the
effects of pure internal secular evolution from those of the merger-driven one
in present-day early-type disks (abridged).Comment: Accepted for publication in Astronomy & Astrophysics, 13 pages, 8
figures. Definitive version after proofs. Added references and corrected
typo
MapReduce-based Solutions for Scalable SPARQL Querying
The use of RDF to expose semantic data on the Web has seen a dramatic increase over the last few years. Nowadays, RDF datasets are so big and rconnected that, in fact, classical mono-node solutions present significant scalability problems when trying to manage big semantic data. MapReduce, a standard framework for distributed processing of great quantities of data, is earning a place among the distributed solutions facing RDF scalability issues. In this article, we survey the most important works addressing RDF management and querying through diverse MapReduce approaches, with a focus on their main strategies, optimizations and results
Spectroscopic Observations of Convective Patterns in the Atmospheres of Metal-Poor Stars
Convective line asymmetries in the optical spectrum of two metal-poor stars,
Gmb1830 and HD140283, are compared to those observed for solar metallicity
stars. The line bisectors of the most metal-poor star, the subgiant HD140283,
show a significantly larger velocity span that the expectations for a
solar-metallicity star of the same spectral type and luminosity class. The
enhanced line asymmetries are interpreted as the signature of the lower metal
content, and therefore opacity, in the convective photospheric patterns. These
findings point out the importance of three-dimensional convective velocity
fields in the interpretation of the observed line asymmetries in metal-poor
stars, and in particular, urge for caution when deriving isotopic ratios from
observed line shapes and shifts using one-dimensional model atmospheres.
The mean line bisector of the photospheric atomic lines is compared with
those measured for the strong Mg I b1 and b2 features. The upper part of the
bisectors are similar, and assuming they overlap, the bottom end of the
stronger lines, which are formed higher in the atmosphere, goes much further to
the red. This is in agreement with the expected decreasing of the convective
blue-shifts in upper atmospheric layers, and compatible with the high velocity
redshifts observed in the chromosphere, transition region, and corona of
late-type stars.Comment: 27 pages, LaTeX; 10 Figures (14 PostScript files); to be published in
The Astrophysical Journa
Ultra-short Period Binaries from the Catalina Surveys
We investigate the properties of 367 ultra-short period binary candidates
selected from 31,000 sources recently identified from Catalina Surveys data.
Based on light curve morphology, along with WISE, SDSS and GALEX multi-colour
photometry, we identify two distinct groups of binaries with periods below the
0.22 day contact binary minimum. In contrast to most recent work, we
spectroscopically confirm the existence of M-dwarf+M-dwarf contact binary
systems. By measuring the radial velocity variations for five of the
shortest-period systems, we find examples of rare cool-white dwarf+M-dwarf
binaries. Only a few such systems are currently known. Unlike warmer white
dwarf systems, their UV flux and their optical colours and spectra are
dominated by the M-dwarf companion. We contrast our discoveries with previous
photometrically-selected ultra-short period contact binary candidates, and
highlight the ongoing need for confirmation using spectra and associated radial
velocity measurements. Overall, our analysis increases the number of
ultra-short period contact binary candidates by more than an order of
magnitude.Comment: 12 pages, 12 figures, accepted Ap
Resins and Gums in Historical Iatrosophia Texts from Cyprus - A Botanical and Medico-pharmacological Approach.
This study explores historical iatrosophia texts from Cyprus from a botanical and medico-pharmacological point of view focusing on remedies containing resins and gums. The iatrosophia are a genre of Greek medical literature of Byzantine origin and can be described as medicine handbooks which serve as therapeutic repositories containing recipes or advice. To extract and analyze information on plant usage in such sources - which are largely unedited texts and so far have not been translated - we investigate (i) the relationship of the iatrosophia to Dioscorides' De Materia Medica as well as historic pharmaceutical books or standard texts on modern phytotherapy and (ii) the validity of the remedies by comparing them to modern scientific data on reported biological activities. In the six texts investigated 27 substances incorporating plant exudates are mentioned. They are obtained from over 43 taxa of higher plants and in particular are used to treat dermatological, gastrointestinal, and respiratory tract conditions. The comparison to historic pharmaceutical books and phytotherapy texts reflects the gradual decline of the use of plant exudates in Western medicine. While remarkable parallels to Dioscorides' text exist, the non-Dioscoridean influence suggests a complex pattern of knowledge exchange. Overall, this resulted in an integration of knowledge from so far poorly understood sources. The comparison with bioscientific data reveals a fragmentary picture and highlights the potential of these unexplored substances and their uses. Where relevant bioscientific data are available, we generally found a confirmation. This points to a largely rational use of the associated remedies. Taken together, the iatrosophia are a valuable resource for ethnopharmacological and natural product research. Most importantly they contribute to the understanding of the development of herbal medicines in the (Eastern) Mediterranean and Europe
Efficacy of DNA amplification in tissue biopsy samples to improve the detection of invasive fungal disease
AbstractThe performance of a pan-fungal PCR-based technique was evaluated to assess the aetiology of invasive fungal diseases (IFDs). A total of 89 formalin-fixed paraffin-embedded biopsy samples from 84 patients with proven IFD were studied. Culture of tissue was performed in 68 (81%) patients. The sensitivities of the PCR-based technique and microbiological culture of tissues were 89% and 56%, respectively (p <0.01). According to PCR results, Aspergillus species accounted for 67%, Candida species for 13%, zygomycetes for 11%, and rare and emerging fungi for 9%. Aspergillus species were significantly associated with lung samples (79.6%, p <0.01), Mucorales were associated with skin/subcutaneous samples, and Candida species were associated with gastrointestinal samples. Regarding biopsy samples with Aspergillus species, Aspergillus fumigatus DNA was detected in 43 of 50 (86%), and Aspergillus flavus in six of 50 (12%). PCR was positive in 24 of 30 (80%) cases with negative culture. In nine of the 84 patients, the PCR technique failed to amplify the DNA. Six also had negative cultures, and in the remaining three cases culture was positive (Rhizopus microsporus, Rhizopus arrhizus, and Sakseneae vasiformis), suggesting that the PCR technique was not as effective in amplifying the DNA of some species of Zygomycetes. In five cases, there was no correlation between culture results and those obtained with DNA amplification, indicating the possibility of a mixed infection or the presence of colonizer/contaminant microorganisms. In summary, PCR-based techniques for DNA amplification should be implemented in histopathology and microbiology departments, as they appear to be complementary to conventional methods for IFD detection
In situ detection of AE2 anion-exchanger mRNA in the human liver
Na+-independent anion exchangers, a family of membrane proteins that mediate electroneutral exchanges of chloride and bicarbonate ions across the cell membrane, are considered to be involved in intracellular pH regulation as well as in transepithelial acid/base transport. Previous immunohistochemical data have shown that anion-exchanger-2 (AE2) protein is expressed in the liver parenchyma, localizing at both the canaliculi and the luminal surfaces of intrahepatic bile ducts, where it may have a role in the biliary secretion of bicarbonate. In the present study, we have carried out in situ hybridization experiments on biopsies of human liver using three overlapping antisense anion-exchanger-2 riboprobes. Anion-exchanger-2 mRNA signals were localized mainly in the cytoplasm of terminal and interlobular bile-duct cells, whereas weaker signals were observed in bile-duct cells of larger intrahepatic ducts. Furthermore, some hepatocytes, mostly periportal, contained detectable anion-exchanger-2 mRNA signals in their cytoplasm. No hybridization signals were observed in controls with sense riboprobes, with omission of the antisense probe, or with treatment of the sections with RNase before hybridizations. Finally, intense anion-exchanger-2 hybridization signals were observed in lymphomononuclear cells in sinusoids and in portal infiltrates. Immunocytochemical data from reverse-phase sections suggest that these cells correspond to some of the CD45R+ (UCHL1+) T lymphocytes resident in the liver
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