Browsing by Author "Perez, C"

Now showing 1 - 5 of 5
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    Body fat and other metabolic effects of atazanavir and efavirenz, each administered in combination with zidovudine plus lamivudine, in antiretroviral-naive HIV-infected patients
    (OXFORD UNIV PRESS INC, 2006) Jemsek, JG; Arathoon, E; Arlotti, M; Perez, C; Sosa, N; Pokrovskiy, V; Thiry, A; Soccodato, M; Noor, MA; Giordano, M
    Background. Protease inhibitor treatment of human immunodeficiency virus (HIV)-infected individuals has been linked to the development of lipodystrophy. The effects of atazanavir on body fat distribution and related metabolic parameters were examined in antiretroviral-naive patients.
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    Circulating platelet-derived microparticles in systemic lupus erythematosus - Association with increased thrombin generation and procoagulant state
    (GEORG THIEME VERLAG KG, 2006) Pereira, J; Alfaro, G; Goycoolea, M; Quiroga, T; Ocqueteau, M; Massardo, L; Perez, C; Saez, C; Panes, O; Matus, V; Mezzano, D
    The risk for thrombosis is significantly increased in systemic lupus erythematosus (SLE), affecting both venous and arterial vessels. Activated platelets are known to participate in thrombus formation and growth. A general feature of activated cells is the shedding of microparticles (MP) which support coagulation by exposure of negatively charged phospholipids and possibly tissue factor (TF). In this work we characterized circulating MP in patients with SLE and their relationship with a procoagulant state. Thirty patients with SLE (aged 15-72 years, mean age 38 years) and 20 healthy controls (aged 22-54 years, mean age 34 years) were studied; patients fulfilled 4 revised criteria for SLE. The number and cellular source of circulating MP were determined by flow cytometry using double labeling with specific monoclonal antibodies and annexin V. Thrombin generation was measured as the endogenous thrombin potential (ETP) without the addition of exogenous phospholipids and TF; under these conditions the generation of thrombin depended directly on the number of MP present in plasma. Thrombin anti-thrombin (TAT) and plasmin-antiplasmin (PAP) complexes were measured by ELISA. Compared to the controls, circulating MP were significantly elevated in the patient group (1218 +/- 136 vs 653 +/- 74 x 10(3)/ml plasma, p: 0.0007). In both groups, most of these MP were of platelet origin (927 +/- 131 vs 517 +/- 72 x 10(3)/ml plasma, p:0.009). ETP was higher among patients as compared to the controls (804 +/- 64 vs 631 +/- 37 nM thrombin, p: 0.025). Plasma levels of TAT in patients and controls were 3.4 +/- 0.8 and 1.4 +/- 0.5 mu g/L, respectively (p:0.04), and of PAP complexes were 62.5 +/- 14 and 24.05 +/- 2.5 mu g/ml, respectively (p:0.014). The number of platelet-derived MP correlated significantly with thrombin generation (r: 0.42; p: 0.038) and TAT levels (r: 0.40; p: 0.035). We did not find an association of circulating MP with disease activity nor with the presence of antiphospholipid antibodies. The increased number of circulating platelet-derived microparticles and their association with high ETP and activation of the coagulation system suggest that these microparticles play an important role in the pathogenesis of the prothrombotic state in SLE patients.
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    Pharmacokinetics of vancomycin in patients with severely impaired renal function
    (DUSTRI-VERLAG DR KARL FEISTLE, 1996) GonzalezMartin, G; Acuna, V; Perez, C; Labarca, J; Guevara, A; Tagle, R
    The pharmacokinetics of 1 g dose of intravenous vancomycin was studied in 8 patients with severe renal failure. Serum vancomycin levels were determined by fluorescence polarization immunoassay. After single dose of vancomycin peak concentrations ranged from 37.8 mu g.ml(-1) to 109.3 mu g. ml(-1) (mean 64.9 +/- 21.7 mu g.ml(-1)). Vancomycin trough concentration 168h after administration of the antibiotic ranged from 2.23 mu g.ml(-1) to 11.42 mu g.ml(-1) (mean 6.55 +/- 2.8 mu g.ml(-1)). The data were analyzed using a PCNONLINE computer program, and in all patients a triexponential model described how concentrations decreased in time. Three-compartment parameters obtained from the 8 patients were t(1/2) alpha = 0.312 +/- 0.242 h, t(1/2) beta 6.012 +/- 5.36 h, and t(1/2) gamma = 131.0 +/- 46.7 h. Vd = 0.158 +/- 0.121 1.kg(-1), Vdss = 0.920 +/- 0.248 1.kg(-1) and total Cl = 0.10 +/- 0.049 1.h(-1) per kg of weight. Between 1.5% and 21.2% of the administered vancomycin dose was eliminated during hemodialysis. The dialysis clearance of vancomycin ranged from 50.6 ml.min(-1) to 76.8 ml.min(-1) (average: 62.4 +/- 10.4 ml.min(-1)). However, after dialysis plasma concentrations returned to pre-dialysis values. In accordance to our kinetic study 1 g of vancomycin given every 7 days is adequate treatment for methicillin-resistant Staphylococcus aureus infections in patients with severe renal failure whose creatinine clearance is lower than 10 ml.min(-1).
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    Saccharomyces cerevisiae fungemia after Saccharomyces boulardii treatment in immunocompromised patients
    (LIPPINCOTT WILLIAMS & WILKINS, 2003) Riquelme, AJ; Calvo, MA; Guzman, AM; Depix, MS; Garcia, P; Perez, C; Arrese, M; Labarca, JA
    Saccharomyces boulardii is widely used as a probiotic compound. Clinical data suggest that this agent is safe and effective. We report two cases of fungemia caused by S. cerevisiae occurring in immunosuppressed patients treated orally with S. boulardii. Molecular typing confirmed clonality in isolate strains from patients and the S. boulardii capsule. Physicians caring for immunosuppressed patients must be aware of this potential serious complication of probiotic use.
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    Simultaneous production of ethanol and kraft pulp from pine (Pinus radiata) using steam explosion
    (ELSEVIER SCI LTD, 1995) Martin, RS; Perez, C; Briones, R
    Radiata pine chips (Pinus radiata) were pretreated by steam explosion, for the simultaneous production of ethanol and pulp. Ethanol was produced fr om the depolymerized hemicellulose fraction recovered after the explosion, while kraft pulp was produced from the steam-exploded chips. The conditions that best balanced sugar recovery and fibre quality were the use of steam alone, at 220 degrees C and short reaction times (e.g. <2 min). After treatment with acid, to depolymerize short-chain oligosaccharides, the hemicellulose hydrolyzate was fermentable to ethanol by yeasts with sugar consumption above 80%. The use of steam explosion reduced the consumption of pulping chemicals. However fibre damage, although minimized significantly at lower reaction times, yielded pulps with lower physical properties than those obtained in conventional kraft pulping.