Browsing by Author "Gonzalez, H"

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    Cerebral oxygenation during postasphyxial seizures in near-term fetal sheep
    (2005) Gonzalez, H; Hunter, CJ; Bennet, L; Power, GG; Gunn, AJ
    After exposure to asphyxia, infants may develop both prolonged, clinically evident seizures and shorter, clinically silent seizures; however, their effect on cerebral tissue oxygenation is unclear. We therefore examined the hypothesis that the increase in oxygen delivery during postasphyxial seizures might be insufficient to meet the needs of increased metabolism, thus causing a fall in tissue oxygenation, in unanesthetized near-term fetal sheep in utero (gestational age 125 +/- 1 days). Fetuses were administered an infusion of the specific adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine, followed by 10mins of asphyxia induced by complete umbilical cord occlusion. The fetuses then recovered for 3 days. Sixty-one episodes of electrophysiologically defined seizures were identified in five fetuses. Tissue PO2 (tPO(2)) did not change significantly during short seizures (< 3.5 mins), 5.2 +/- 0.2 versus baseline 5.6 +/- 0.1 mm Hg (NS), but fell to 2.2 +/- 0.2 mm Hg during seizures lasting more than 3.5mins (P < 0.001). During prolonged seizures, cortical blood flow did not begin to increase until tPO(2) had begun to fall, and then rose more slowly than the increase in metabolism, with a widening of the brain to blood temperature gradient. In conclusion, in the immature brain, during prolonged, but not short seizures, there is a transient mismatch between cerebral blood flow and metabolism leading to significant cerebral deoxygenation.
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    Epileptiform activity during rewarming from moderate cerebral hypothermia in the near-term fetal sheep
    (2005) Gerrits, LC; Battin, MR; Bennet, L; Gonzalez, H; Gunn, AJ
    Moderate hypothermia is consistently neuroprotective after hypoxic-ischemic insults and is the subject of ongoing clinical trials. In pilot studies, we observed rebound seizure activity in one infant during rewarming from a 72-h period of hypothermia. We therefore quantified the development of EEG-defined seizures during rewarming in an experimental paradigm of delayed cooling for cerebral ischemia. Moderate cerebral hypothermia (n = 9) or sham cooling (n = 13) was initiated 5.5 It after reperfusion from a 30-min period of bilateral carotid occlusion in near-term fetal sheep and continued for 72 h after the insult. During spontaneous rewarming, fetal extradural temperature rose from 32.5 +/- 0.6degreesC to control levels (39.4 +/- 0.1degreesC) in 47 +/- 6 min. Carotid blood flow and mean arterial blood pressure increased transiently during rewarming. The cooling group showed a significant increase in electrical seizure events 2, 3, and 5 h after rewarming, maximal at 2 h (2.9 +/- 1.2 versus 0.5 +/- 0.5 events/h; p < 0.05). From 6 h after rewarming, there was significant difference between the groups. Individual seizures were typically short (28.8 +/- 5.8 s versus 29.0 +/- 6.8 s in sham cooled; NS), and of modest amplitude (35.9 +/- 2.8 versus 38.8 +/- 3.4 muV; NS). Neuronal loss in the parasagittal cortex was significantly reduced in the cooled group (51 +/- 9% versus 91 +/- 5%; p < 0.002) and was not correlated with rebound epileptiform activity. In conclusion, rapid rewarming after a prolonged interval of therapeutic hypothermia can be associated with a transient increase in epileptiform events but does not seem to have significant adverse implications for neural outcome.
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    Microcarcinoma tiroideo de evolución agresiva
    (2005) Mosso, L; Jimenez, M; Gonzalez, H; Solar, A; Torres, J; Fardella, C; NCD Risk Factor Collaboration (NCD-RisC)
    The treatment of papillary thyroid carcinoma of less than 10 mm diameter is a matter of controversy. The incidental finding of papillary microcarcinomas in autopsies is frequent and some authors postulate that these tumors are biologically inactive and should only be observed. We report a 21 years old woman with a papillary thyroid cancer of 6x5x5 mm and bilateral paratracheal metastases, that leas subjected to a total thyroidectomy. She received 200 mCi of radioiodine. Two years after surgery, a new nodule of 9.6 Mm diameter was detected by ultrasound, that was treated with a new dose of 200 1,170 of radioiodine. One year later a suprasternal mass of 2 cm diameter and 3 enlarged lymph nodes were detected. She was subjected to a surgical lymph node dissection of the neck and the biopsy confirmed the presence of cancer. She received a new dose of 300 mCi of radioiodine. The mother of the patient had a 7 mm thyroid nodule that was also a papillary carcinoma.
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    Pathological characteristics of thyroid microcarcinoma. A review of 402 biopsies
    (2005) Fardella, C; Jimenez, M; Gonzalez, H; Leon, A; Goni, I; Cruz, F; Solar, A; Torres, J; Mosso, L; Gonzalez, G; Rodriguez, JA; Campusano, C; Lopez, JM; Arteaga, E
    Background: Thyroid microcarcinoma is a tumor of 10 mm or less. that should have a low risk of mortality. However a subgroup of these carcinomas is as aggressive as bigger tumors. Aim To describe the pathological presentation of these tumors.. and compare them with larger tumors. Material and methods. All Pathological samples of thyroid carcinoma that were obtained between 1992 and 2003, were studied. In all biopsies, the pathological type, tumor size. the focal or multifocal character the presence of lymph node involvement and the presence of lymphocytic thyroiditis or thyroid hyperplasia, were recorded. Results: One hundred eighteen microcarcinomas and 284 larger tumors were studied. The mean age of patients with microcarcinoma and larger tumors was 42.7 +/- 14 and 49.3 +/- 16 years respectively (p < 0,00.1) and 83% were female. without gender differences between tumor types. klean size of microcarcinomas was 8.6 mm and 116 (98%) were papillary carcinomas. Of these. 109 (94% were well differentiated and seven (6%) were moderatly differentiated. Thirty six(31%) were multifocal and in 10 (8,6%), there was lymph node involvement. The mean size of larger tumors was 23.8 mm and 241 (85%) were papillary carcinomas. Of these, 200 (83%) were well differentiated, and 41 (17%) were moderately differentiated.Eighty five (35%) were multifocal and in 44 (18%) there was lymph node involvement. The prevalence of thyroiditis and hyperplasia was significantly higher among microcardinomas than in larger tumors (15 and 2.5%, respectively, p < 0.001, for the former; 32.4 and 1.7%, respectively, p < 0.001, for the latter. Conclusions. In this series. one third of microcarcinomas were multifocal and 10% had lymph node involvement. Therefore, aggresiveness of these tumors is higher than what is reported in the literature and they should be treated with total thyroidectomy.
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    Regression of left ventricular hypertrophy in experimental renovascular hypertension: Diastolic dysfunction depends more on myocardial collagen than it does on myocardial mass
    (1996) Dussaillant, GR; Gonzalez, H; Cespedes, C; Jalil, JE
    Objective To evaluate regression of experimental left ventricular hypertrophy (LVH) in terms of its effects both on myocardial collagen levels and on diastolic stiffness.