Browsing by Author "TAPIA, J"

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    ENCEPHALOGRAPHY WITH METRIZAMIDE
    (1977) CORRALES, M; TAPIA, J
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    HISTOLOGIC ASSESSMENT OF THE AGE OF RECENT BRAIN INFARCTS IN MAN
    (1993) CHUAQUI, R; TAPIA, J
    In order to design a dating system based on the microscopic picture of brain infarcts of recent onset, we performed the histological examination of 31 infarcts covering the first 4 weeks of evolution in 30 autopsy cases. The date of the cerebral vascular accident was clinically established in every case. There were 13 men and 17 women with a mean age of 65 years. Hemorrhagic infarcts were found in 15 cases and anemic infarcts in 16 cases. Based on the histological features four periods were identified: the first period, from day 1 through day 4, was characterized by the predominance of eosinophilic neurons and necrotic oligodendrocytes; the second period, from day 5 through day 7, differed from the first by the appearance of macrophages and of newly formed blood vessels; the third period, from day 8 through day 14, showed neuronal ghosts, macrophages, astrocytic proliferation, gemistocytes, and absence of neutrophils; and in the fourth period, from day 15 through day 27, there were no eosinophilic neurons, and neither necrotic oligodendrocytes nor myelin in the central portion of the infarct were identified. By assessing the histological features and accurately correlating the findings with the corresponding clinical data, we have been able to describe four distinct microscopic pattems of the first month of evolution of brain infarcts. The present findings may be considered useful morphological clues to better characterize the early evolutional phase of brain infarcts in humans.
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    INTRAVASCULAR LYMPHOMATOSIS (MALIGNANT ANGIOENDOTHELIOMATOSIS) - A B-CELL NEOPLASM EXPRESSING SURFACE HOMING RECEPTORS
    (1988) FERRY, JA; HARRIS, NL; PICKER, LJ; WEINBERG, DS; ROSALES, RK; TAPIA, J; RICHARDSON, EP
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    RISK-FACTORS FOR SYSTEMIC EMBOLISM IN PATIENTS WITH PAROXYSMAL ATRIAL-FIBRILLATION
    (MOSBY-ELSEVIER, 1992) CORBALAN, R; ARRIAGADA, D; BRAUN, S; TAPIA, J; HUETE, I; KRAMER, A; CHAVEZ, A
    The purpose of this study was to define the risk factors for systemic embolism in patients with recently diagnosed paroxysmal atrial fibrillation. We therefore studied 63 consecutive patients with symptomatic nonvalvular paroxysmal atrial fibrillation and performed a clinical and noninvasive cardiac, peripheral vascular, and neurologic evaluation that included two-dimensional echocardiography, 24-hour Holter monitoring, and computed tomographic brain scan. Patients with predisposing clinical conditions for systemic embolism (valvular heart or coronary artery disease) or paroxysmal atrial fibrillation (sick sinus disease, preexcitation, or thyroid dysfunction) were excluded. At entry 34 patients had idiopathic paroxysmal atrial fibrillation and 29 had hypertension. Fourteen patients had a recent systemic embolic complication: nine had a recent occlusive nonlacunar cerebrovascular accident, two had transient ischemic attacks, and three had peripheral systemic emboli that required surgery. In addition, five patients had evidence of old cerebrovascular accident on the computed tomographic scan (group 1). Forty-four patients had no systemic embolism (group 2). Results of univariate analysis showed that patients in group 1 were older (72 +/- 9 vs 63 +/- 13 years, p < 0.05), had a higher incidence of hypertension (70% vs 35%, p < 0.01), and had an increased left atrial diameter (4.1 +/- 0.7 vs 3.6 +/- 0.5 cm, p < 0.05). Multiple stepwise logistic regression analysis showed that a history of hypertension and left atrial enlargement on two-dimensional echocardiography were significant independent risk factors for systemic embolism in patients with symptomatic nonvalvular paroxysmal atrial fibrillation.
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    SYNTHETIC LIGNIN MINERALIZATION BY CERIPORIOPSIS-SUBVERMISPORA IS INHIBITED BY AN INCREASE IN THE PH OF THE CULTURES RESULTING FROM FUNGAL GROWTH
    (1995) TAPIA, J; VICUNA, R
    C-14-synthetic lignin mineralization by the basidiomycete Ceriporiopsis subvermispora occurs at the highest rate (about 30% after 29 days) in Liquid cultures containing 1% glucose and a growth-limiting amount (1 mM) of ammonium tartrate. The titers of manganese peroxidase (MnP) and laccase are lower in these cultures than in cultures containing 1% glucose and 10 mM ammonium tartrate, where the extent of lignin mineralization in the same period is only about 15%. The inverse correlation between enzyme activity and lignin mineralization is also observed when ammonium tartrate is replaced by ammonium chloride or Casamino Acids as the source of nitrogen. This phenomenon can be explained by a gradual increase in the pH of the medium that takes place only in the cultures with high nitrogen concentrations. Supporting this finding, when cultures with 1 mM ammonium tartrate were grown at different pHs, (CO2)-C-14 evolved more rapidly from those with pH values near the optimum for MnP activity. On the other hand, (CO2)-C-14 evolution from cultures containing 1% glucose supplemented with 1 mM ammonium tartrate plus 9 mM sodium tartrate was as low as that from cultures with a high ammonium tartrate concentration. Since the changes in the pH of these cultures were not as pronounced as those in cultures containing high nitrogen concentrations, tartrate itself may also be contributing to limit the extent of lignin mineralization. Considering that pH instability seems to constitute a common feature of fungal cultures, precautions must be taken to avoid underestimation of their ligninolytic efficiencies.