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Biomedical subjects

V Penna

Publications and source records attributed to V Penna.

6 recordsLinked to original sources
PubMed2003

Dynamical instability in a trimeric chain of interacting bose-einstein condensates.

We analyze thoroughly the mean-field dynamics of a linear chain of three coupled Bose-Einstein condensates, where both the tunneling and the central-well relative depth are adjustable parameters. Owing to its nonintegrability, entailing a complex dynamics with chaos occurrence, this system is a paradigm for longer arrays whose simplicity still allows a thorough analytical study. We identify the set of dynamics fixed points, along with the associated proper modes, and establish their stability character depending on the significant parameters. As an example of the remarkable operational value of our analysis, we point out some macroscopic effects that seem viable to experiments.

Journal Article↗
PubMed1991

IIB osteosarcoma. Current management, local control, and survival statistics--São Paulo, Brazil.

Ninety-two patients with IIB osteosarcoma of the extremities were treated with intraarterial (IA) cisplatinum (CDDP) followed by surgery [amputation (61.6%) or resection with endoprosthesis (38.4%)]. Postoperative chemotherapy alternating adriamycin and CDDP was used. The total three-year survival was 62.1%, and the disease-free survival was 41.1%. The pathologic evaluation of the degree of tumor necrosis in response to the IA CDDP showed that in 53.2%, the necrosis was over 90%. The multivariate analysis of prognostic factors has shown that the highest survival was among females with tumors smaller than 15 cm. Patients with lesions equal to or larger than 15 cm were three times as likely to die of the disease. A second, more aggressive study is now underway, in which high dose methotrexate (HDMTX) is preoperatively combined with adriamycin and CDDP. Following operation, ifosfamide is added to the cases with a smaller degree of tumor necrosis, while the other group of patients will continue with HDMTX, in addition to CDDP and adriamycin (these last two drugs are used in both arms). Until now, complete remission has been achieved in 82% and 86%, respectively, with a follow-up examination varying from four to 26 months (average, 14 months). This is of extreme importance, because the majority of the authors' patients have tumors at initial evaluation larger than 10 cm in diameter.

Amputation, Surgical↗
PubMedDate not supplied

Solitary plasmocytoma of bone in an adolescent.

PURPOSE: To describe an adolescent with solitary plasmocytoma of bone and compare the pathologic and radiographic findings with osteomyelitis. PATIENT AND METHODS: A 17-year-old girl had a 3-year history of swelling of the right tibia, local pain, and hyperemia. RESULTS: Initial biopsy was interpreted as osteomyelitis. The lesion was rebiopsied 3 years later and showed a plasma cell neoplasm. A review of the first biopsy confirmed a similar histologic picture. CONCLUSION: Although solitary plasmocytoma of bone is a rare neoplasm in adolescence, it must be considered in the differential diagnosis of chronic osteomyelitis.

Adolescent↗