429 research outputs found
L-arginine uptake, the citrulline-NO cycle and arginase II in the rat brain: an in situ hybridization study
Nitric oxide (NO) is synthesized from a unique precursor, arginine, by nitric oxide synthase (NOS). In brain cells, arginine is supplied by protein breakdown or extracted from the blood through cationic amino acid transporters (CATs). Arginine can also be recycled from the citrulline produced by NOS activity, through argininosuccinate synthetase (AS) and argininosuccinate lyase (AL) activities, and metabolized by arginase. NOS, AS and AL constitute the so-called citrulline-NO cycle. In order to better understand arginine transport, recycling and degradation, we studied the regional distribution of cells expressing CAT1, CAT3, AS, AL, neuronal NOS (nNOS) and arginase II (AII) in the adult rat brain by non-radioisotopic in situ hybridization (ISH). CAT1, AL and AII presented an ubiquitous neuronal and glial expression, whereas CAT3 and AS were confined to neurons. nNOS was restricted to scattered neurons and a few brain nuclei and layers. We demonstrate by this study that cells expressing nNOS all appear to express the entire citrulline-NO cycle, whereas numerous cells expressing AL do not express AS. The differential expression of these genes within the same anatomical structure could indicate that intercellular exchanges of citrulline-NO cycle metabolites are relevant. Thus vicinal interactions should be taken into account to study their regulatory mechanisms
Differential expression of the cationic amino acid transporter 2(B) in the adult rat brain
L-Arginine is a substrate for the synthesis of proteins, nitric oxide (NO), creatine, urea, proline, glutamate, polyamines and agmatine. In the central nervous system (CNS), arginine is extracted from the blood and exchanged by cells through carriers called cationic amino acid transporters (CAT) and belonging to the so-called system y+. In order to better understand the arginine transport in the CNS, we studied in detail the regional distribution of the cells expressing the CAT2(B) transcript in the adult rat brain by non-radioisotopic in situ hybridization. We show that CAT2(B) is expressed in neurons and oligodendrocytes throughout the brain, but is not detected in astrocytes. The pattern of localization of CAT2(B) in the normal adult rat brain fits closely that of CRT1, a specific creatine transporter. Our study demonstrates that the in vivo expression of CAT2(B) differs from that reported in vitro, implying that local cellular interactions should be taken into account in studies of gene regulation of the CAT2(B) gene. Our work suggests that CAT2(B) may play a role in case of increased NO production as well as arginine or creatine deficiency in the brain
Sera from Trypanosoma b. gambiense infected patients cross-react with a Trypanosoma cruzi recombinant protein
In previous studies, we and others have shown utility of a 24-kDa #Trypanosoma cruzi recombinant antigen (rTc24) for serological diagnosis of Chagas' disease. Also, this molecule has been proved useful to evaluate cure of chagasic patients who submit to specific treatment. However, in all the studies done so far, the 24-kDa protein was used as a fusion with a Gluthatione-S-transferase (GST) of #Schistosoma japonicum, therefore, parallel assays to determine the anti-GST responses of all sera were required to deduce the GST noise in serological tests. Here, we show the subcloning by polymerase chain reaction of the cDNA encoding the #T. cruzi$ 24-kDa antigen in a vector system (pQE) allowing us to obtain Tc24 recombinant protein as a single molecule. The highly reactivity of chagasic sera from Colombia, Ecuador, Brazil and Bolivia in ELISA against the recombinant antigen is confirmed. However, sera from patients infected with African trypanosomes recognize rTc24 in ELISA and blot. The relevance of these findings in the context of Chagas' disease diagnosis and/or the relationship with African trypanosomes is analyzed. (Résumé d'auteur
MSX versus IRAS Two-Color Diagrams and the CSE-Sequence of Oxygen-Rich Late-Type Stars
We present MSX two-color diagrams that can be used to characterize
circumstellar environments of sources with good quality MSX colors in terms of
IRAS color regions for oxygen-rich stars. With these diagrams we aim to provide
a new tool that can be used to study circumstellar environments and to improve
detection rates for targeted surveys for circumstellar maser emission similar
to the IRAS two-color diagram. This new tool is especially useful for regions
in the sky where IRAS was confused, in particular in the Galactic plane and
bulge region. Unfortunately, using MSX colors alone does not allow to
distinguish between carbon-rich and oxygen-rich objects. An application of this
tool on 86 GHz SiO masers shows that for this type of masers an instantaneous
detection rate of 60% to 80% can be achieved if target sources are selected
according to MSX color (region).
Our investigations may have revealed an error in the MSX point source catalog
version 2.3. That is, the photometry of the 21.3 m (MSX E filter) band for
most weak 8.28 m (or MSX A filter) band sources seems off by about a
factor two (0.5--1 magnitude too bright).Comment: accepted to Astrophysical Journal, 11 pages, 11 figs of which 1 in
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The Quantum Group Structure of 2D Gravity and Minimal Models II: The Genus-Zero Chiral Bootstrap
The F and B matrices associated with Virasoro null vectors are derived in
closed form by making use of the operator-approach suggested by the Liouville
theory, where the quantum-group symmetry is explicit. It is found that the
entries of the fusing and braiding matrices are not simply equal to
quantum-group symbols, but involve additional coupling constants whose
derivation is one aim of the present work. Our explicit formulae are new, to
our knowledge, in spite of the numerous studies of this problem. The
relationship between the quantum-group-invariant (of IRF type) and
quantum-group-covariant (of vertex type) chiral operator-algebras is fully
clarified, and connected with the transition to the shadow world for
quantum-group symbols. The corresponding 3-j-symbol dressing is shown to reduce
to the simpler transformation of Babelon and one of the author (J.-L. G.) in a
suitable infinite limit defined by analytic continuation. The above two types
of operators are found to coincide when applied to states with Liouville
momenta going to in a suitable way. The introduction of
quantum-group-covariant operators in the three dimensional picture gives a
generalisation of the quantum-group version of discrete three-dimensional
gravity that includes tetrahedra associated with 3-j symbols and universal
R-matrix elements. Altogether the present work gives the concrete realization
of Moore and Seiberg's scheme that describes the chiral operator-algebra of
two-dimensional gravity and minimal models.Comment: 56 pages, 22 figures. Technical problem only, due to the use of an
old version of uuencode that produces blank characters some times suppressed
by the mailer. Same content
Operator Coproduct-Realization of Quantum Group Transformations in Two Dimensional Gravity, I.
A simple connection between the universal matrix of (for
spins \demi and ) and the required form of the co-product action of the
Hilbert space generators of the quantum group symmetry is put forward. This
gives an explicit operator realization of the co-product action on the
covariant operators. It allows us to derive the quantum group covariance of the
fusion and braiding matrices, although it is of a new type: the generators
depend upon worldsheet variables, and obey a new central extension of
realized by (what we call) fixed point commutation relations. This
is explained by showing that the link between the algebra of field
transformations and that of the co-product generators is much weaker than
previously thought. The central charges of our extended algebra,
which includes the Liouville zero-mode momentum in a nontrivial way are related
to Virasoro-descendants of unity. We also show how our approach can be used to
derive the Hopf algebra structure of the extended quantum-group symmetry
U_q(sl(2))\odot U_{\qhat}(sl(2)) related to the presence of both of the
screening charges of 2D gravity.Comment: 33 pages, latex, no figure
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