509 research outputs found
Beta gamma-subunit activation of G-protein-regulated phospholipase C
The availability of purified G alpha 11 and the G-protein-regulated phospholipase C from turkey erythrocytes has allowed an examination of the direct effects of G-protein beta gamma-subunit on the components of the inositol lipid signaling system. Reconstitution of purified turkey erythrocyte or bovine brain beta gamma-subunit into phospholipid vesicles containing G alpha 11 inhibited AlF4- induced activation of phospholipase C. However, beta gamma-subunit at higher concentrations increased phospholipase C activity. This stimulatory effect of beta gamma-subunit on phospholipase C did not require the presence of the alpha-subunit. G alpha o had no effect on the catalytic activity of phospholipase C. However, coreconstitution of G alpha o and beta gamma-subunit shifted to the right the concentration-effect curve for beta gamma-subunit-promoted activation of phospholipase C. As was observed with G alpha 11, the increase in activity observed in the presence of beta gamma-subunit occurred as an increase in the maximal activity and with no change in the apparent affinity for Ca2+ for phospholipase C activation. The concentration dependence of G alpha 11 for activation of turkey erythrocyte phospholipase C and bovine brain phospholipase C-beta, as well as the concentration dependence of the two enzymes for activation by G alpha 11, were very similar. In contrast, beta gamma-subunit was a much less effective activator of bovine brain phospholipase C-beta than the turkey erythrocyte enzyme. The observation of direct effects of free beta gamma-subunit on phospholipase C extend the possibilities for receptor-mediated regulation of this signaling pathway
A Portable High Speed Ultrasonic Imaging System
Acoustical holography is rapidly approaching commercial status with applications to nondestructive evaluation, underwater imaging, and underground pipe location being pursued. In this paper we review the techniques involved, show some experimental results, and describe the latest commercial system
Degenerate Stars and Gravitational Collapse in AdS/CFT
We construct composite CFT operators from a large number of fermionic primary
fields corresponding to states that are holographically dual to a zero
temperature Fermi gas in AdS space. We identify a large N regime in which the
fermions behave as free particles. In the hydrodynamic limit the Fermi gas
forms a degenerate star with a radius determined by the Fermi level, and a mass
and angular momentum that exactly matches the boundary calculations. Next we
consider an interacting regime, and calculate the effect of the gravitational
back-reaction on the radius and the mass of the star using the
Tolman-Oppenheimer-Volkoff equations. Ignoring other interactions, we determine
the "Chandrasekhar limit" beyond which the degenerate star (presumably)
undergoes gravitational collapse towards a black hole. This is interpreted on
the boundary as a high density phase transition from a cold baryonic phase to a
hot deconfined phase.Comment: 75 page
Cisplatin and vinorelbine first-line chemotherapy in non-resectable malignant pleural mesothelioma
The aim was to evaluate the activity of cisplatin and vinorelbine in previously untreated, inoperable patients having histologically verified malignant pleural mesothelioma (MPM), normal organ function, and performance status 0–2. Treatment was vinorelbine 25 mg m−2 i.v. weekly and cisplatin 100 mg m−2 i.v. every 4 weeks with hydration and standard prophylactic antiemetic treatment. Patients gave written informed consent. Characteristics of 54 consecutive patients were: males 85%, epithelial subtype 74%, IMIG stages III and IV 35 and 46%, performance status 0, 1, and 2, 26, 69, and 6%, and median age 63 years (31–78 years). CTC grade 3 or 4 toxicity occurred with respect to leukocytopenia (48% of patients, grade 4 in 13%), nausea (13%), neurotoxicity (11%), nephrotoxicity (4%), and other toxicities (9%). There were no toxic deaths. The median number of cycles was four. The fraction of patients alive at 1-, 2-, and 3-years were 61, 31, and 4%, respectively, and median survival and median time to progression were 16.8 months (0.5 to 46.4 +months) and 7.2 months (1.6 to 40.6 + months). There were two CRs and 14 PRs (response rate 29.6%). Cisplatin and intravenous vinorelbine is a highly active regimen in MPM with a response rate and survival comparable to the most active regimens so far reported
Quantum Algorithms for the Most Frequently String Search, Intersection of Two String Sequences and Sorting of Strings Problems
We study algorithms for solving three problems on strings. The first one is
the Most Frequently String Search Problem. The problem is the following. Assume
that we have a sequence of strings of length . The problem is finding
the string that occurs in the sequence most often. We propose a quantum
algorithm that has a query complexity . This algorithm
shows speed-up comparing with the deterministic algorithm that requires
queries. The second one is searching intersection of two sequences
of strings. All strings have the same length . The size of the first set is
and the size of the second set is . We propose a quantum algorithm that
has a query complexity . This algorithm shows
speed-up comparing with the deterministic algorithm that requires
queries. The third problem is sorting of strings of length
. On the one hand, it is known that quantum algorithms cannot sort objects
asymptotically faster than classical ones. On the other hand, we focus on
sorting strings that are not arbitrary objects. We propose a quantum algorithm
that has a query complexity . This algorithm shows
speed-up comparing with the deterministic algorithm (radix sort) that requires
queries, where is a size of the alphabet.Comment: THe paper was presented on TPNC 201
Hierarchical information clustering by means of topologically embedded graphs
We introduce a graph-theoretic approach to extract clusters and hierarchies
in complex data-sets in an unsupervised and deterministic manner, without the
use of any prior information. This is achieved by building topologically
embedded networks containing the subset of most significant links and analyzing
the network structure. For a planar embedding, this method provides both the
intra-cluster hierarchy, which describes the way clusters are composed, and the
inter-cluster hierarchy which describes how clusters gather together. We
discuss performance, robustness and reliability of this method by first
investigating several artificial data-sets, finding that it can outperform
significantly other established approaches. Then we show that our method can
successfully differentiate meaningful clusters and hierarchies in a variety of
real data-sets. In particular, we find that the application to gene expression
patterns of lymphoma samples uncovers biologically significant groups of genes
which play key-roles in diagnosis, prognosis and treatment of some of the most
relevant human lymphoid malignancies.Comment: 33 Pages, 18 Figures, 5 Table
Antenatal screening for Group B Streptococcus: A diagnostic cohort study
BACKGROUND: A range of strategies have been adopted to prevent early onset Group B Streptococcal (EOGBS) sepsis, as a consequence of Group B Streptococcal (GBS) vertically acquired infection. This study was designed to provide a scientific basis for optimum timing and method of GBS screening in an Australian setting, to determine whether screening for GBS infection at 35–37 weeks gestation has better predictive values for colonisation at birth than screening at 31–33 weeks, to examine the test characteristics of a risk factor strategy and to determine the test characteristics of low vaginal swabs alone compared with a combination of perianal plus low vaginal swabs per colonisation during labour. METHODS: Consented women received vaginal and perianal swabs at 31–33 weeks gestation, 35–38 weeks gestation and during labour. Swabs were cultured on layered horse blood agar and inoculated into selective broth prior to analysis. Test characteristics were calculated with exact confidence intervals for a high risk strategy and for antenatal screening at 31–33 and 35–37 weeks gestation for vaginal cultures alone, perianal cultures alone and combined low vaginal and perianal cultures. RESULTS: The high risk strategy was not informative in predicting GBS status during labour. There is an unequivocal benefit for the identification of women colonised with GBS during labour associated with delaying screening until 36 weeks however the results for method of screening were less definitive with no clear advantage in using a combined low vaginal and perianal swabbing regimen over the use of a low vaginal swab alone. CONCLUSION: This study can contribute to the development of prevention strategies in that it provides clear evidence for optimal timing of swabs. The addition of a perianal swab does not confer clear benefit. The quantification of advantages and disadvantages provided in this study will facilitate communication with clinicians and pregnant women alike
Electro-thermal modelling for plasmonic structures in the TLM Method
This paper presents a coupled electromagnetic-thermal model for modelling temperature evolution in nano-size plasmonic heat sources. Both electromagnetic and thermal models are based on the Transmission Line Modelling (TLM) method and are coupled through a nonlinear and dispersive plasma material model. The stability and accuracy of the coupled EM-thermal model is analysed in the context of a nano-tip plasmonic heat source example
Signaling of the human P2Y(1) receptor measured by a yeast growth assay with comparisons to assays of phospholipase C and calcium mobilization in 1321N1 human astrocytoma cells
The human P2Y(1) receptor was expressed in the yeast Saccharomyces cerevisiae strain MPY578q5, which is engineered to couple to mammalian G protein-coupled receptors (GPCRs) and requires agonist-induced activation for growth. A range of known P2Y(1) receptor agonists were examined with the yeast growth assay system, and the results were validated by comparing with potencies in the transfected 1321N1 astrocytoma cell line, in which calcium mobilization was measured with a FLIPR (fluorometric-imaging plate reader). The data were also compared with those from phospholipase C activation and radioligand binding with the use of a newly available radioligand [(3)H]MRS2279 (2-chloro-N(6)-methyl-(N)-methanocarba-2’-deoxyadenosine-3’,5’bisphosphate). In the yeast growth assay, the rank order of potency of 2-MeSADP (2-methylthioadenosine 5’-diphosphate), ADP (adenosine 5’-diphosphate), and ATP (adenosine 5’-triphosphate) is the same as those in other assay systems, i.e., 2-MeSADP>ADP>ATP. The P2Y(1)-selective antagonist MRS2179 (N(6)-methyl-2-deoxyadenosine-3’,5’-bisphosphate) was shown to act as an antagonist with similar potency in all systems. The results suggest that the yeast expression system is suitable for screening P2Y(1) receptor ligands, both agonists and antagonists. The yeast system should be useful for random mutagenesis of GPCRs to identify mutants with certain properties, such as selective potency enhancement for small synthetic molecules and constitutive activity
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