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Gilberto González

Publications and source records attributed to Gilberto González.

4 recordsLinked to original sources
PubMed2003

Performance analysis of ultrasono-therapy transducer with contact detection.

The performance of ultrasono-therapy transducer with contact detection by using the impedance phase change is described. Usually a therapy transducer is designed with a lambda/2 frontal plate glued to a PZT-4 piezoceramic. This plate ensures a good mechanical protection of the piezoceramic with a corresponding high-transmission energy. Normally this transducer is operated at the minimum at the frequency of the impedance module of its input electric impedance, but this operation point is affected by the shift caused by the expected temperature increase. This shift could be higher than the narrow bandwidth presented. As a result we obtain a decrease in the power level for medical treatment. Usually it is designed electronic drivers with automatic control that follow the frequency change, but the relatively narrow bandwidth introduces difficulty in the design. Another frequency operation point is presented here and analyzed using the criteria of the maximum of the impedance phase with a wider bandwidth than in the previous case. Simulation with mechanical losses are presented with experimental results that show the convenience of this criteria for practical application.

Equipment Failure Analysis↗
PubMed2003

[Paget disease of bone in Chile: report of 15 cases].

BACKGROUND: Paget disease of bone (PD) is a localized disorder of bone remodeling, which leads to bone fragility and deformity. In Chile PD is uncommon. AIM: To study clinical and demographic characteristics of patients with PD seen in the Clinical Hospital of the Catholic University. PATIENTS AND METHODS: Patients with typical radiological and clinical features of PD referred to our institution during the last decade were included in this review. RESULTS: We obtained data from 15 patients with PD (ten males, eight Chilean, six European and one Asian), eleven of them were diagnosed during the last 3 years. The mean age at diagnosis was 68.7 +/- 11.1 years old. No one had first degree relatives with PD. Bone pain was the main complaint in 13 patients and elevated total alkaline phosphatases in the other two. The average duration of the symptoms prior to diagnosis was 38.8 months. Eight patients had monostotic lesions; the most commonly involved sites were the pelvis, spine and femur. Radiological evaluation disclosed sclerotic changes in all patients as well as bone deformity and osteoarthritis in eight patients. Total alkaline phosphatases were elevated in 14 cases (mean: 4 times over the upper normal limit). CONCLUSIONS: When compared to series of the Northern hemisphere, PD in Chile is characterized by an older age at diagnosis, a higher frequency of symptomatic presentation, advanced radiological involvement and greater proportion of complications. PD should be suspected in every patient, Chilean or foreigner, with bone pain or elevated alkaline phosphatases.

Age of Onset↗
PubMed2002

[Anti thyroglobulin antibodies in the follow up of patients with differentiated thyroid cancer: residual or relapsing disease markers?].

BACKGROUND: Anti thyroglobulin antibodies are present in 25% of patients treated for a differentiated thyroid cancer, invalidating thyroglobulin determination. Those patients subjected to total thyroidectomy and free of disease, should reduce the production of these antibodies, due to the lack of antigenic stimulus. Therefore, anti thyroglobulin antibodies could be useful to detect early relapses. AIM: To assess the relationship between anti thyroglobulin antibodies and the evolution of the disease in patients treated for thyroid cancer. MATERIAL AND METHODS: Retrospective analysis of 26 patients treated for thyroid cancer with positive anti thyroglobulin antibodies, followed for three years. These were divided in those with or without lymphocytic thyroiditis (19 and 7 respectively). RESULTS: At the first year of follow up, anti thyroglobulin antibody concentration was 401 +/- 94.9 UI/ml (x +/- sem) in patients with thyroiditis and 38.9 +/- 8.9 UI/ml in those without thyroiditis (p < 0.005). During the three years of follow up, no differences in anti thyroglobulin antibodies were observed between patients with or without tumor relapse. CONCLUSIONS: Concentration of anti thyroglobulin antibodies was higher in patients with thyroiditis and did not differentiate patients with tumor relapse.

Adult↗