[Chondromyxoid fibroma of the thoracic spine: a case report and review of the literature]

A case of chondromyxoid fibroma (CMF) arising from the 5th right costovertebral junction and spreading into spinal canal causing spinal cord compression is presented. A myelotomography revealed a complete block at T5 level. The patient underwent a decompressive laminectomy with removal of an epidural tumor. This specimen was sent for pathological examination and interpreted as a CMF. The patient had a neurological improvement, post operative MRI revealed a spinal cord free of compression, and we decided on the follow up of the case. Two years later there was recurrence of the tumor. A posterolateral access by costotransversectomy was made and the lesion was resected. The patient had a neurological improvement which persists on the follow up (two years, at present). Clinical, radiologic and histologic findings, surgical management and recurrence are discussed. The pertinent literature is reviewed.

Genetic variation of foot-and-mouth disease virus during persistent infection in cattle

Genetic variation of foot-and-mouth disease virus O1 Campos has been analyzed in consecutive isolates recovered over a one- or two-year period from four cattle with experimental persistent infection. Comparisons of RNase T1 two-dimensional maps and nucleotide sequences of the VP1-coding region revealed a continual, although irregular, increase in the fixation of mutations as the infection progressed. Most changes were not conserved in consecutive isolates. These results, together with the substantial rates of genomic variation observed between some pairs of strains recovered at close time periods, suggested the coexistence of heterogeneous populations in which variants evolve independently from each other, and predominate at irregular time intervals. Furthermore, non-related patterns of variation were observed in the four animals. Similarly, genetic diversity of representative strains from major serotype O outbreaks in endemic disease regions of southeastern Brazil and central eastern Argentina which occurred between 1958 and 1983, suggested that outbreak strains are also likely to represent fluctuations of heterogeneous populations which evolve independently from each other. The possible role of persistent infections in the introduction of variant populations in the field is discussed.

Biochemical characterization of an aphthovirus type C3 strain Resende attenuated for cattle by serial passages in chicken embryos

We have compared several aspects of an aphthovirus strain attenuated for cattle (C3R-O/E) with the original strain (C3Res) from which it was derived after serial passages in chicken embryos. Biochemical differences detected by protein analysis in regular polyacrylamide gels (SDS-PAGE) and on electrofocusing gels (NEPHGE) suggest the presence of mutations throughout the genome. Changes were located in coat proteins VP1 and VP3 and in the polymerase precursor P100 (P3/ABCD). No other differences were found at the protein level by means of the techniques used. Polypeptide P100 of the attenuated strain showed a faster electrophoretic mobility in SDS-PAGE with respect to that of the wild-type strain, and the change seems to be located on its amino terminus half. Several functional differences were also found between the two viruses. Both strains grew equally well in BHK cells reaching roughly similar titers in plaque assays. However, the wild-type strain maintained its titer in cells of bovine origin (BK), whereas the titer of C3R-O/E strain decreased approximately one log in this cell system; moreover, plaques elicited by the attenuated strain were much smaller than the ones produced by C3Res. A diminution in the rate of RNA synthesis induced by C3R-O/E in BK cells compared with that of the wild-type strain was also detected; this trait was not observed in BHK cells. A delay in the kinetics of RNA synthesis was also detected in this strain. The virus yield of attenuated strain in BK cells was four times lower than in BHK cells.