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Abstract:  Aneurysmal bone cyst of the long bones in a purely intracortical or subperiosteal location is unusual. Three such cases are reported, and the radiographic and pathologic differential diagnoses are discussed.Those subperiosteal or intracortical aneurysmal bone cysts with radiographic features similar to the intramedullary variety should suggest the same diagnosis. However, the radiographic features may be less specific, so that a diagnosis of aneurysmal bone cyst must be entertained when considering a subperiosteal or intracortical lytic lesion.

Abstract:  Objective.To demonstrate the radiologic and pathologic manifestations of osteoid osteoma arising beneath the periosteum, on the surface of the bone. Design. One hundred and sixty osteoid osteomas were seen over a 30-year period. The radiologic, pathologic and operative findings of those that were subperiosteal were reviewed. Patients. Eleven patients with subperiosteal osteoid osteoma were reviewed. The patients ranged in age from 13 to 36 years with a mean of 24 years. Eight were male and three were female. Results and conclusion. Eleven subperiosteal lesions were studied. The reactive periostitis of four lesions was atypical and misleading. Four lesions had features similar to the more common intracortical variety. Three lesions occurring within the joint like other intra-articular lesions were barely seen on plain radiographs. Bone scan and CT scan were virtually diagnostic. The histopathology of these lesions was also atypical though not misleading. In conclusion, subperiosteal osteoid osteoma is a rare lesion with atypical radiographic and histopathologic features. The unusual reactive periostitis seen in several extra-articular cases may suggest other diagnoses.

Seven tripeptides of leucine and valine of the optical configuration L-L-D were synthesized by the mixed anhydride procedure. Configuration of each amino acid in the peptides was established bacterimetrically. Racemization was found on the internal amino acid.

Nitrogen-15 from single tagged feeding has been used to measure nitrogen in urine from a given protein source. Comparative studies of retention of absorbed protein in young and older subjects have been presented. The average retention in the young subjects was found to be 57.6%, but only 49.1% in the older subjects. The half-life of N15from yeast in the body was found to average 75 days for the entire group studied: for the young controls 61 days and for the older subjects 86 days. The rate of protein turnover in the young controls was found to be approximately one and one half times that in the older subjects. Increased physiologic age would seem a probable cause for this reduced utilization of protein. The average nitrogen requirement from the pool for protein synthesis in the body was found to be 0.23 gm per kilogram per day. The nitrogen requirement for maintenance for a 70-kg man was found to be 16 gm per day.

Methods for the study of protein absorption in man have been discussed. A yeast protein tag with an N15content of 58.3 atom % excess was prepared. Evidence for the general distribution of the tag throughout the protein fraction of the yeast has been reviewed. Comparative absorption studies in young and old subjects have been presented. A mean yeast protein absorption of 90.3% among 6 subjects has been determined. Achlorhydria, hypochlorhydria, and age do not appear to produce depressing effects on the capacity to absorb a protein tracer during continued high-level protein intake. The role of gastric acidity in protein utilization will be further discussed in a subsequent communication. The single-dose tracer method of determining protein absorption has been shown to obviate the need for evaluation of endogenous nitrogen.