Isolation and characterization of a distinct immunoregulatory isoform of alpha-fetoprotein produced by the normal fetus

In this report, we examine the functional significance of the molecular microheterogeneity of alpha-fetoprotein (AFP). In doing so, we have taken the direct approach of purifying the naturally occurring isomeric forms of fetal-derived AFP using a preparative anion exchange column linked to an automated fast protein liquid chromatography (FPLC) system followed by parallel testing of each isolated molecular variant for in vitro immunoregulatory activity. The data obtained demonstrate the presence of seven distinct variants of AFP as defined by their retention volumes on FPLC elution profiles, by their pIs on analytical IEF gels, and by Western blot analysis. Molecular mass determination by SDS-PAGE showed each isomer to be equivalent in size to 69,000-dalton native unfractionated AFP molecules. All the immunosuppressive activity of AFP was localized to a single variant representing only 6% of the total composition of native AFP. The immunoregulating isomer termed AFP-1 was the least acidic of the seven isolated variants with a pI of 5.1 and displayed a sialic acid content of 1 mol/mol of protein. The inhibitory activity of AFP-1 could be readily measured on T cell-dependent antibody synthesis, Con A-induced stimulation of Lyt-1+23- thymocyte DNA synthesis, and lymphokine-activated NK cell activity. All other isomers were without effect in these test systems. The immunosuppressive AFP-1 isomer also displayed the strongest growth-promoting influence on cultured bone marrow lymphocytes. There was no correlation between functional activity and degree of expression of sialic acid residues on the AFP molecules. These findings demonstrate that the immunoregulating function of AFP is confined to a distinct and relatively small subpopulation of native AFP molecules and should therefore contribute to the resolution of outstanding questions regarding the structure/function relationship of this onco-fetal glycoprotein.     

Computerized tomography and Trotter's syndrome in the diagnosis of maxillofacial pain

Trotter's syndrome is a clinical triad of unilateral deafness, neuralgia affecting branches of the trigeminal nerve, and defective mobility of the soft palate, which is caused by malignant tumors involving the lateral pharyngeal recess (Rosenmüller's fossa). It is an ominous presentation, which can masquerade as dental or masticatory pain. Computerized tomography (CT) can be used not only to explain the anatomic basis of Trotter's syndrome but also to determine the extent and distribution of the malignant tumor involved. The advantages of CT over conventional radiography are illustrated by a case of adenoid cystic carcinoma that presented as Trotter's syndrome. Perineural invasion by tumor is shown on the gross level for the first time with CT, and important diagnostic considerations, which may aid in the early diagnosis of future cases, are discussed.     

Three different pathogenic mechanisms for paraparesis in association with bacterial infections

Three different pathogenic mechanisms are apparent for paraparesis in association with a bacterial infection: a spinal cord compression caused by either an epidural abscess or a vertebral collapse due to spondylitis, an ischaemic spinal cord lesion as a result of septic thromboembolus in abdominal aorta, and a nonspecific, probably immunological, cause in association with reactive polyarthritis. An example of each of these mechanisms is described by means of case histories.     

Adjustment and adaptation

As in many other scientific disciplines, in gerontology adaptation is a central term. Yet it is not being used in a standardized way. This article describes the concepts and theoretical approaches which can be identified in Social Gerontology, together with their functions and the results of research.     

Diagnosis of Ewing sarcoma of the thoracic spine--differential diagnostic difficulties

Spinal Ewing's sarcomas are rare and cause problems in differential diagnosis. The radiologic, nuclear medicine and CT findings in two children with histologically proven Ewing's sarcoma are presented and problems in differential diagnosis discussed. Biopsy should be done early.