Evaluation of the differentiation potential of WB-F344 rat liver epithelial stem-like cells in vivo. Differentiation to hepatocytes after transplantation into dipeptidylpeptidase-IV-deficient rat liver.

After intrahepatic transplantation into livers of adult syngeneic German-strain Fischer 344 rats that are deficient for the bile canalicular enzyme dipeptidyl peptidase IV (DPP-IV), cultured WB-F344 rat liver epithelial cells (without exogenous marker genes) integrate into hepatic plates and differentiate into hepatocyte-like cells that are morphologically and functionally indistinguishable from mature hepatocytes. In this model system, the differentiated progeny of transplanted WB-F344 cells are identified among the DPP-IV-negative host hepatocytes by their expression of bile canalicular DPP-IV enzyme activity. DPP-IV-positive hepatocyte-like cells also expressed other markers of hepatocytic differentiation, including albumin, transferrin, and alpha-1-antitrypsin, suggesting that the progeny of transplanted WB-F344 cells express a complete hepatocyte differentiation program. These results complement our previous studies indicating WB-F344 cells can serve as stem-like precursor cells for differentiated hepatocytes and strengthen the suggestion that WB-F344 rat liver epithelial cells represent the cultured counterpart of liver stem-like hepatocyte progenitor cells present in the normal adult rat liver.     

The role of the pontis oralis in the generation of RSA activity in the hippocampus of the guinea pig

The relationship between field activity in the nucleus pontis oralis (PnO) and the hippocampus was examined in the guinea pig. Rhythmical slow activity (RSA or theta activity) could be recorded from both the pontis oralis and the hippocampus. RSA recorded in the pontis oralis was of the same principal frequency as that found in the hippocampus, but had a much lower amplitude. Behavioral correlates of PnO RSA were the same as the behavioral correlates of hippocampal RSA. The effects of atropine sulfate on RSA were the same at each site. Stimulation of the PnO produced RSA in the hippocampus. Lesions of the PnO had no effect on RSA recorded from the hippocampus or on the behavioral correlates of this RSA. Lesions of the medial septum abolished RSA in both sites. Cross-correlations between field activity recorded from both the hippocampus and PnO showed the same time lag before and after septal lesions. These results indicate that while the PnO is not instrumental in the production of hippocampal RSA, an intact septum is necessary for the production of RSA in both sites. They also indicate that there is a common projection to these sites which does not pass through the medial septum.     

Rectal syphilis mimicking histiocytic lymphoma

Homosexuality is being recognized with increasing frequency in the United States, and the physician must be knowledgeable of the presentations of venereal infection in this population. A 23-year-old man who denied homosexuality presented with a rectal mass and diffuse adenopathy. Biopsy of the mass was interpreted as histiocytic lymphoma. Subsequent serology had positive results for syphilis. Further questioning revealed a history of anorectal intercourse, and special stains of the mass revealed spirochetes. Syphilis must be considered in any young patient presenting with a rectal mass, regardless of the biopsy histologic characteristics or sexual history.     

Long-term follow-up of the Indiana conservative resurfacing hip arthroplasty

Sixty-four Indiana conservative (Depuy, Warsaw, IN) hip arthroplasties performed in 61 patients were reviewed for loosening, mechanisms of loosening, and revision rate. Mean follow-up time was 6.8 years. There were revisions in 26 hips (40.6%) with 4 hips awaiting revision, yielding a total of 30 hips (47%) defined as failures. Acetabular failure occurred in 20 hips, femoral failure in 18, and combined failure in 13. Failure of this prosthesis persists over time. There seems to be little or no place for this design in contemporary hip joint arthroplasty.     

Expression of hepatocyte and oval cell antigens in hepatocellular carcinomas produced by oncogene-transfected liver epithelial cells

We have established an in vivo/in vitro system in which epithelial cells ("oval cells") isolated from livers of rats fed a carcinogenic diet for a very brief period are placed in culture and transfected with an oncogene. Injection s.c. into nude mice of oval cells transfected with the activated c-Ha-ras (EJ oncogene) produces tumors with morphological features of differentiated hepatocellular carcinomas. Using monoclonal antibodies that can recognize hepatocyte, oval cell, and tumor antigens, we investigated the expression of these antigens in oval cells in culture, transfected with either the EJ oncogene or the normal c-Ha-ras allele and in tumors derived from the oncogene-transfected cells. We show that EJ-transfected cells and most particularly the tumors they produce expressed hepatocyte and oval cell antigens not detectable in untransfected cells or cells transfected with the normal c-Ha-ras gene. Furthermore, we found that in cloned tumor cells, the expression of hepatocyte antigens could be induced by changes in culture conditions and was accompanied by a decrease in the expression of oval cell markers. Trabecular hepatocellular carcinomas had higher reactivity toward monoclonal antibodies recognizing hepatocyte antigens while tumors with glandular architecture reacted predominantly with monoclonal antibodies against oval cells. We conclude that, in addition to its tumorigenic effect, the EJ oncogene induced the differentiation of tumor cells toward the hepatocyte lineage. In addition, the data provide further confirmation that oval cells can serve as progenitors of differentiated hepatocellular carcinomas.