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| Registros recuperados: 992 | |
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| ROJO,DANIEL; SUETOMI,KATSUTOSHI; NAVARRO,JAVIER. |
| Chemokine receptors are G protein-coupled receptors that mediate migration and activation of leukocytes as an important part of a protective immune response to injury and infection. In addition, chemokine receptors are used by HIV-1 to infect CD4 positive cells. The structural bases of chemokine receptor recognition and signal transduction are currently being investigated. High-resolution X-ray diffraction and NMR spectroscopy of chemokines indicate that all these peptides exhibit a common folding pattern, in spite of its low degree of primary-sequence homology. Chemokines' functional motifs have been identified by mutagenesis studies, and a possible mechanism for receptor recognition and activation is proposed, but high-resolution structure data of... |
| Tipo: Journal article |
Palavras-chave: Chemokines; G-protein coupled receptors; Inflammation; HIV-1. |
| Ano: 1999 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97601999000400006 |
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| PINCHEIRA,J; LÓPEZ,I; SANHUEZA,S; FERRUZ,P; NAVRRETE,MH; SANTOS,MJ; LÓPEZ-SÁEZ,JF. |
| The effect of the G2 repair of chromosomal damage in lymphocytes from workers exposed to low levels of X- or g-rays was evaluated. Samples of peripheral blood were collected from 15 radiation workers, 20 subjects working in radiodiagnostics, and 30 healthy control donors. Chromosomal aberrations (CA) were evaluated by scoring the presence of chromatid and isochromatid breaks, dicentric and ring chromosomes in lymphocytes with/without 5mM caffeine plus 3mM-aminobenzamide (3-AB) treatment during G2. Our results showed that the mean value of basal aberrations in lymphocytes from exposed workers was higher than in control cells (p< 0.001). The chromosomal damage in G2, detected with caffeine plus 3-AB treatment was higher than the basal damage... |
| Tipo: Journal article |
Palavras-chave: Chromosome aberrations ionizing radiation; G2 repair; Human lymphocytes; Occupational exposure. |
| Ano: 1999 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97601999000400009 |
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| HIDALGO,CECILIA; BULL,RICARDO; MARENGO,JUAN J; PÉREZ,CLAUDIO F; DONOSO,PAULINA. |
| The effects of redox reagents on the activity of the intracellular calcium release channels (ryanodine receptors) of skeletal and cardiac muscle, or brain cortex neurons, was examined. In lipid bilayer experiments, oxidizing agents (2,2'-dithiodipyridine or thimerosal) modified the calcium dependence of all single channels studied. After controlled oxidation channels became active at sub µM calcium concentrations and were not inhibited by increasing the calcium concentration to 0.5 mM. Subsequent reduction reversed these effects. Channels purified from amphibian skeletal muscle exhibited the same behavior, indicating that the SH groups responsible for modifying the calcium dependence belong to the channel protein. Parallel experiments that... |
| Tipo: Journal article |
Palavras-chave: Calcium dependence; Neurons; Redox state; Ryanodine receptors; Sarcoplasmic reticulum; Skeletal and cardiac muscle. |
| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602000000200011 |
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| VALENZUELA,CARLOS Y.. |
| Neutral evolution results from random recurrent mutation and genetic drift. A small part of random evolution, that which is related to protein or DNA polymorphisms, is the subject of the Neutral Theory of Evolution. One of the foundations of this theory is the demonstration that the mutation rate (m) is equal to the substitution rate. Since both rates are independent of population size, they are independent of drift, which is dependent upon population size. Neutralists have erroneously equated the substitution rate with the fixation rate, despite the fact that they are antithetical conceptions. The neutralists then applied the random walk stochastic model to justify alleles or bases that were fixated or eliminated. In this model, once the allele or base... |
| Tipo: Journal article |
Palavras-chave: Neutral evolution; Neutral theory; Misconceptions; Bases fixation; Elimination. |
| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602000000300004 |
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| CANALS,MAURICIO; OLIVARES,RICARDO; LABRA,FABIAN; NOVOA,FRANCISCO F. |
| Respiration and metabolism change dramatically over the course of the development of vertebrates. In mammals these changes may be ascribed to organogenesis and differentiation of structures involved in gas exchange and transport and the increase in size. Since young as well as mature individuals must be well-designed if the species is to survive, the physiological changes during the development should be matched with geometrical or structural adjustments of the respiratory system. The aim of this study was to evaluate changes in the fractal geometry of the bronchial tree during the postnatal development of the rat. The average fractal dimension of the bronchial tree of the rats was 1.587, but that of juveniles was larger than that of the adults. We found... |
| Tipo: Journal article |
Palavras-chave: Bronchial tree; Fractals; Ontogeny. |
| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602000000100010 |
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| Registros recuperados: 992 | |
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