Coherent contributions to isospin mixing in the mirror pair 67As and 67Se.

Isospin symmetry breaking has been investigated in mass A=67 mirror nuclei through the experimental determination of the E1 strengths of analog electromagnetic transitions. Lifetimes of excited states have been measured in (67)Se and (67)As with the centroid shift method. Through the comparison of the B(E1) strengths of the mirror 9/2(+)-->7/2(-) transitions, the isovector and the isoscalar components of the electromagnetic transition amplitude were extracted. The presence of a large isoscalar component provides evidence for coherent contributions to isospin mixing, probably involving the isovector giant monopole resonance.

Coulomb energy differences in t = 1 mirror rotational bands in (50)Fe and (50)Cr.

Gamma rays from the N = Z-2 nucleus (50)Fe have been observed, establishing the rotational ground state band up to the state J(pi) = 11+ at 6.994 MeV excitation energy. The experimental Coulomb energy differences, obtained by comparison with the isobaric analog states in its mirror (50)Cr, confirm the qualitative interpretation of the backbending patterns in terms of successive alignments of proton and neutron pairs. A quantitative agreement with experiment has been achieved by exact shell model calculations, incorporating the differences in radii along the yrast bands, and properly renormalizing the Coulomb matrix elements in the pf model space.

Evaluation of homoplastic bone graft in hip replacement revision surgery.

A total of 17 patients submitted to hip replacement revision surgery in our clinic between 1986 and 1994 were evaluated in order to analyze the effectiveness of homoplastic support grafting. Loss of substance involved the acetabulum and the femur. Four parameters were evaluated radiographically: fusion time, restructuring time, flattening or collapse of grafts, and, finally, graft resorption. The results showed that the homoplastic graft is characterized by excellent biological behavior, and that the success of the new implant depends mostly on surgical method used as the graft was always integrated quickly and completely. In cases with considerable loss of substance it is important to use means of support that allow for partial unloading of the forces between prosthesis and host bone, thus avoiding excessive loading in the grafts.

Chondrosarcoma as a complicating factor in Paget's disease of bone.

A 65-year-old male patient with an 8-year history of poliostotic Paget's disease complained of shoulder pain that started 6 months prior to admission. An extensive lytic area was identified in the right proximal humerus along with Paget's disease. There was cortical destruction and a soft tissue mass. Following an incisional biopsy, a diagnosis of grade 2 chondrosarcoma associated with Paget's disease was made. The histologic identification of chondrosarcoma associated with Paget's disease is rare. However, the presence of a calcified matrix in a destructive lesion associated with Paget's disease should alert the radiologist and the pathologist to the possibility of a chondromatous differentiation taking place in the sarcoma associated with Paget's disease. The histologic evaluation of the lesion will form the basis for the diagnosis.