Browsing by Author "Valenzuela, R"

Now showing 1 - 5 of 5
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    Effects of carvedilol on oxidative stress and chronotropic response to exercise in patients with chronic heart failure
    (WILEY, 2005) Castro, P; Vukasovic, JL; Chiong, M; Diaz Araya, G; Alcaino, H; Copaja, M; Valenzuela, R; Greig, D; Perez, O; Corbalan, R; Lavandero, S
    Background: Our previous studies suggest that the increase in heart rate from rest to peak exercise is reduced in patients with chronic heart failure (CHF) and this is associated with increased oxidative stress, as determined by malondialdehyde (MDA) plasma levels.
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    Evaluation of the Stability of Fatty Acids in Erythrocytes from Human Umbilical Cord
    (2020) Jaramillo, AM; Garmendia, ML; Muñoz, P; Corbari, A; Valenzuela, R; Casanello Toledo, Paola Cecilia
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    High-affinity binding of fatty acyl-CoAs and peroxisome proliferator-CoA esters to glutathione S-transferases -: Effect on enzymatic activity
    (1999) Silva, C; Loyola, G; Valenzuela, R; García-Huidobro, T; Monasterio, O; Bronfman, M
    Acyl-CoAs an present at high concentrations within the cell, yet are strongly buffered by specific binding proteins in order to maintain a low intracellular unbound acyl-CoA concentration, compatible with their metabolic role? their importance in cell signaling, and as protection from their detergent properties. This intracellular regulation may be disrupted by nonmetabolizables acyl-CoA esters of xenobiotics, such as peroxisome proliferators, which are formed at relatively high concentration within the liver cell. The low molecular mass acyl-CoA binding protein (ACBP) and fatty acyl-CoA binding protein (FABP) have been proposed as the buffering system for fatty acyl-CoAs. Whether these proteins also bind xenobiotic-CoA is not known. Here we have identified new liver cytosolic fatty acyl-CoA and xenobiotic-CoA binding sites as glutathione S-transferase (GST), using fluorescent polarization and a acyl-etheno-CoA derivative of the peroxisome proliferator nafenopin as ligand. Rat liver GST and human liver recombinant GSTA1-1, GSTP1-1 and GSTM1-1 were used. Only class alpha rat liver GST and human GSTA1-1 bind xenobiotic-CoAs and fatty acyl-CoAs, with K-d values ranging from 200 nM to 5 mu M. One mol of acyl-CoA is bound per mol of dimeric enzyme, and no metabolization or hydrolysis was observed. Binding results in strong inhibition of rat Liver GST and human recombinant GSTA1-1 (IC50 at the nanomolar level for palmitoyl-CoA) but not GSTP1-1 and GSTM1-1. Acyl-CoAs do not interact with the GSTA1-1 substrate binding site, but probably with a different domain. Results suggest that under increased acyl-CoA concentration, as occurs after exposure to peroxisome proliferators, acyl-CoA binding to the abundant class alpha GSTs may result in strong inhibition of xenobiotic detoxification, Analysis of the binding properties of GSTs and other acyl-CoA binding proteins suggest that under increased acyl-CoA concentration GSTs would be responsible for xenobiotic-CoA binding whereas ACBP would preferentially bind fatty acyl-CoAs.
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    Late motor deficits of Chilean manganese miners: A blinded control study
    (1996) Hochberg, F; Miller, G; Valenzuela, R; McNelis, S; Crump, KS; Covington, T; Valdivia, G; Hochberg, B; Trustman, JW
    High-level chronic manganese (Mn) exposure produces dystonic rigidity and proximal tremor. The late effects of asymptomatic exposure are uncertain. To evaluate hand movements of asymptomatic Chilean miners, we utilized a manual tremormeter (EAP) and a digitizing tablet (MOVEMAP). In Andacollo, Chile, we examined 59 individuals aged >50 years (mean age, 64.4 years). Twenty-seven exposed miners had heavy Mn dust exposure in Mn mines for more than 5 years (mean duration, 20.25 years), ending at least 5 years previously. Thirty-two control miners had never worked in Mn mines or had short-term Mn employment. Tests of resting tremor (EAP Tremormeter, MOVEMAP Steady paradigm), action tremor (MOVEMAP Square paradigm), and repetitive hand movements (EAP Tapping Test and Ortho-kinesimeter) differentiated performance of exposed miners from that of controls. Chronic asymptomatic Mn exposure results in detectable late-life abnormalities of movement.
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    Temporal crescent syndrome. Report of one case
    (SOC MEDICA SANTIAGO, 2004) Mery, V; Mellado, P; Valenzuela, R; Luco, C; Huete, I
    The temporal crescent syndrome or half-moon syndrome is a rare mono ocular retrochiasmatic visual field defect that cart be correlated to a lesion along the contralateral parieto-occipital sulcus. This field defect may be missed in automated perimetry. We report a 45 years old man, consulting for sudden loss of the peripheral temporal field in his right eye. The magnetic resonance imaging and the spectroscopy studies confirmed an ischemic lesion on the left anterior occipital cortex. Control imaging studies six months later did not show changes in the lesion.