Antibody-associated paraneoplastic cerebellar degeneration (the Yo syndrome) is an uncommon disorder in which an immune response is specifically directed against tumor tissue and the cerebellum. Screening of a A expression library has resulted in the isolation of cDNA clones that encode the major antigen recognized by serum from these patients. The fusion protein produced by the cDNA clones provides the basis of a simple diagnostic assay for this neurological syndrome. The occurrence of leucine-zipper and zinc-finger motifs in the predicted open reading frame suggests that this protein plays a role in the regulation of gene expression.Paraneoplastic cerebellar degeneration is a disorder of the cerebellum found in association with neoplasms of lung, ovary, breast, or Hodgkin disease (1). Neuropathological analysis of affected brains has revealed extensive loss of Purkinje cells, variable loss of granule and basket neurons, and proliferation of Bergman glia (2). The relationship between the primary tumor and the resultant cerebellar dysfunction is not clearly understood. The presence of infiltrating lymphocytes in some of the affected brains has suggested an immune mechanism (3).A clinically definable subset of patients with paraneoplastic cerebellar degeneration harbor a characteristic antibody that has been called anti-Yo (4). Sera from these patients react with antigens expressed in the Purkinje cells of the normal cerebellum and in the tumor tissue of affected individuals (5). There is also evidence of increased antibody synthesis in the affected brains (6). These observations suggest a model for the neurological dysfunction in which an immune response primarily directed against a tumor antigen is misdirected against similar antigens peculiar to the cerebellum. On Western blot analysis of Purkinje cells and tumor tissue, the anti-Yo sera react with at least two antigens, a major species of 62 kDa (CDR-62) and a minor species of 34 kDa (CDR-34) (where CDR is cerebellar degeneration related) (7). The gene encoding the minor antigen (CDR-34) has been isolated and characterized (8,9). We now report the isolation of cDNAs that encode the major Yo paraneoplastic antigen. Sequence analysis § revealed CDR-62 to be a member of a family of the leucine-zipper DNA binding proteins. The availability of the recombinant protein has provided a simple diagnostic assay for the presence of anti-Yo antibodies.MATERIALS AND METHODS Sera from patients with antibody-associated paraneoplastic cerebellar degeneration was obtained from their physicians.A HeLa cell A ZAP expression library was obtained from Stratagene.Screening of A HeLa Expression Library. Recombinant phage were screened at a density of 2 x 104 plaque-forming units per 150-mm plate of Escherichia coli XLI-Blue. After incubation for 6 hr at 370C, the plates were overlaid with filters soaked in isopropyl 8-D-thiogalactopyranoside (10 mM) and incubated for a further 12 hr at 370C. The filters were then removed and incubated with anti-Yo sera (IgG, 2 tug/ml) for 2 ...

Omental pregnancy is a rare form of abdominal pregnancy. In the 5 previously reported cases, primary implantation of the embryo to the omentum has been proposed as its etiology. We present a new case of omental pregnancy in a 31-year-old woman presenting with symptoms of ectopic pregnancy. After careful review of our case and the published literature in view of the accepted definition of primary abdominal pregnancy, we conclude that all reported instances of omental pregnancy are secondary and probably follow tubal or ovarian pregnancy abortion.

A cDNA library was prepared from a terminal deoxynucleotidyltransferase-containing thymoma in the X phage vector Xgtll. By screening plaques with anti-terminal transferase antibody, positive clones were identified of which some had 3..galactosidase-cDNA fusion proteins identifiable after electrophoretic fractidhatioh by immunoblotting with anti-terminal transferase antibody. The iredosinant class of cross-hybridizing clones was determined to represent cDNA for terminal transferase by showing that one representative clone hybridized to a 2200-nucleotide mRNA in close-matched enzyftae-positive but not to enzyme-negative cells and that the cDNA selected a mRNA that translated to give a protein of the size and antigenic characteristics of terminal transferase. Only a small amount of genomic DNA hybridized to the longest available clone, indicating that the sequence is virtually unique in the mouse genome.Terminal deoxynucleotidyltransferase (TdT) is a unique DNA polymerase that without template direction catalyzes the addition of deoxyribonucleotides onto the 3'-hydroxyl ends of DNA primers (1-3). It is present in the immature fraction of thymocytes (4-7), in a small fraction of bone marrow cells (5, 8), in transformed pre-B-and pre-T-cell lines (9, 10), and in leukemic cells (6, 11). The enzyme purified by the method of Yoneda and Bollum (12) and Chang and Bollum (13) is a dimer of Mr 26,000 and Mr 8,000 chains. This structure is, however, an artifactual result of proteolytic cleavage during the purification. The enzyme is synthesized as a single chain of Mr 58,000 in mice and Mr 55,000-60,000 in humans (14-18).The function of TdT is not fully established. It was suggested that the enzyme might be responsible for somatic point mutation of immunoglobulin genes (19), but it now appears that somatic point mutation occurs late in B-lymphocyte maturation, when cells no longer contain TdT (20,21). A recent proposal that TdT might be responsible for inserting nucleotides (N regions) at VH-D and D-JH (22) junctions (junctions of heavy chain variable-diversity and diversityjoining region genes) has received experimental support (unpublished results). N-region insertion in a T-cell receptor chain may also occur (23) and is possibly a result of the relatively high TdT levels in thymocytes.We describe here the isolation from a thymoma cell line cDNA library of a clone that encodes TdT. Because the amino acid sequence of TdT has not been reported, there was no nucleic acid probe available for screening recombinants. Instead, specific antibodies raised against the purified twochain bovine enzyme, which cross-react with the murine enzyme, were used to probe a cDNA library constructed in the Xgtl1 expression system of Young and Davis (24). As well as providing a cDNA clone with which to characterize TdT, this work shows the feasibility of cloning ctlNA representations of rare mRNAs with conventional antibody reagents. METHODS Xgtl1 cDNA Library Construction. Double-stranded cDNA was synthesized from 20 gg of RL 11 poly(A)-...

A 1750 base pair cDNA to human terminal deoxynucleotidyl transferase (TdT) has been cloned. This cDNA detects a dominant 2200 base pair messenger RNA species in normal and leukemic cells synthesizing the enzyme. A quantitative dot blot assay was utilized to survey a number of clinical samples from patients with TdT positive and negative leukemias as well as cells from normal volunteers. A linear relationship was detected between the amount of TdT mRNA and the amount of enzyme activity in bone marrow cells. The assay is sensitive enough to detect normal TdT levels in bone marrow, and distinguish these levels from the lack of such mRNA in peripheral blood and bone marrow of patients with myeloid leukemia. Elevated levels of mRNA were found in two cases of patients in clinical remission. The prognostic significance of these observations must await further study.