Nuclei, isolated from paraffh-embedded tissue, were stained with propidium iodide (PI) and found suitable for DNA analysis by flow cytometry (FCM). DNA-derived fluorescence intensity, however, was always decreased and had a much higher intersample variability as compared to results obtained with fresh material. Using chicken red blood cells (CRBC) as a model system, we found the lower fluorescence intensity to be due to the fomalin fixation step in tissue processing. The intersample variability was found to be at least partly caused by variations in the duration of fixation. Overnight trypsinization improved the fluorescence intensity but did not reduce the intersample variability. Under all conditions tested PI binding to CRBC appeared to be saturable. Since fresh diploid or red blood cells could not be used to standardize DNA histograms, an alternative approach was developed in which nuclei from paraffinembedded normal and tumor tissue of the same specimen were mixed. With this method DNA indices @I) of 24 colorectal cancers were found to be closely correlated (r = 0.9877, P < 0.001) with DI obtained with fresh tumor tissue from the same patients. The correlation of the percentages of S-phase nuclei between paraffin-extracted and fresh samples (r = 0.5875, P < 0.05) was as high as could be expected, taking sampling differences into account. This method is an important tool for the retrospective analysis of FCM-derived DNA parameters in relation to diagnosis and prognosis of neoplasms.

Hyperexpression of MRP is frequently observed in primary NSCLC, especially in the well differentiated squamous cell carcinomas. Further studies are needed to assess the role of MRP in the mechanism of clinical drug resistance in NSCLC.

Cytomegalovirus infection of Brown Norway rats was studied after intraperitoneal or subcutaneous inoculation of virus. No clinical illness was apparent during the 1st month postinfection (p.i.). Low titers of virus were detected in many organs at day 4 p.i. for the intraperitoneally inoculated animals and at day 11 p.i. for those inoculated subcutaneously. Thereafter, the virus disappeared from all tested organs except the salivary glands, where it appeared on day 11 p.i. and reached high levels by 4 weeks p.i. Histologically, no abnormalities were observed. The virus had an immunosuppressive effect during the 1st week p.i., as indicated by the immune response to sheep red blood cells.

An experimental rat model to study acute cytomegalovirus infections is described. Eight-week old male Brown Norway rats, immunosuppressed by total body irradiation, were infected with rat cytomegalovirus (RCMV). The effects of infection were determined by survival rates and the presence of virus or viral components in different organs was assayed by plaque test, immunoperoxidase staining, dot-blot DNA hybridization and in situ DNA hybridization. At days 10-post infection nearly 90% of the animals had died. Spleen, liver and bone marrow were heavily infected. Interstitial pneumonia was observed. Pathological findings strongly resembled the full scale of lesions in human CMV infections. Anti-RCMV hyperimmune serum was effective against mortality from RCMV infection and viral spread to lungs and liver was prevented. This model is appropriate for studies on the pathogenesis and antiviral therapy of CMV infections in the immunocompromised host.

The E‐cadherin–catenin complex is important for cell–cell adhesion of epithelial cells. Impairment of one or more components of this complex is associated with poor differentiation and increased invasiveness of carcinomas. Oesophageal adenocarcinomas causes early metastases, progress rapidly, and consequently have a poor prognosis. By means of immunohistochemistry, the expression of E‐cadherin and alpha‐ and beta‐catenin was studied in 65 oesophageal adenocarcinomas and 15 lymph node metastases. Expression of these proteins was evaluated with respect to clinico‐pathological parameters and patient survival. Expression of the proteins was strongly correlated. In carcinomas, reduced expression of E‐cadherin, alpha‐catenin, and beta‐catenin was found in 74, 60, and 72 per cent, respectively. Expression of E‐cadherin and alpha‐catenin correlated significantly with stage and grade of the carcinomas, whereas expression of beta‐catenin correlated only with grade. Reduced expression of all three proteins correlated with shorter patient survival. In contrast to grade, E‐cadherin and beta‐catenin were significant prognosticators for survival, independent of disease stage. We conclude that in oesophageal adenocarcinomas, decreased expression of E‐cadherin, alpha‐catenin and beta‐catenin are related events. Furthermore, expression of at least E‐cadherin and beta‐catenin is significantly correlated with poor prognosis. © 1997 John Wiley & Sons, Ltd.