Osteoid osteoma and osteoblastoma: reclassification of 43 cases using Schajowicz's classification.

Forty-three cases of benign osteoblastic tumour of bone from the University of British Columbia bone tumour registry have been reviewed and reclassified according to the classification of Schajowicz and Lemos. Their classification has the advantage that the relationship of the two lesions is recognized and overlap, both radiologically and microscopically, is allowed for. The terminology used in the new classification, however, is cumbersome and confusing and appears to be of no great advantage. We therefore recommend instead the terminology modified from that of Dias and Frost, which incorporates the observations put forth by Schajowicz and Lemos: (a) cortical osteoblastoma, (b) medullary osteoblastoma, (c) periosteal osteoblastoma and (d) multifocal osteoblastoma.

Physicochemical effects of aldehydes on the human erythrocyte.

The effects of formaldehyde, acetaldehyde, and glutaraldehyde on human red blood cells were investigated. It was found that (a) The surface negative charge of the erythrocytes at pH 7 was increased 10% by glutaraldehyde, but not by the other two aldehydes. (b) The effect of incomplete fixation of the red blood cells was demonstrated by hemoglobin leakage studies The leakage of hemoglobin subsequent to formaldehyde treatment was especially pronounced Acetaldehyde-fixed cells showed some leakage of hemoglobin after an hour of exposure to the fixative, whereas glutaraldehyde-fixed cells showed no hemoglobin leakage. (c) All three aldehydes caused K(+) leakage during fixation. The concentrations of K(+) in the fixing solutions all reached the same level, but whereas the leakage with glutaraldehyde was immediate, that with formaldehyde was more gradual and that with acetaldehyde reached a steady state only after 24 hr. (d) The effects of the aldehydes on red cell deformability and swelling revealed that glutaraldehyde hardened the cells within 15 min, formaldehyde within 5 hr, while acetaldehyde required at least 24 hr to produce appreciable fixation. (e) The hematocrit changes accompanying the fixation process depended upon cell volume changes and loss of deformability.