Proliferation patterns of cervical cells as visualized in Leiden liquid cytology slides

The Leiden liquid-based cytology method for the preparation of optimal cytological slides is reported. In such slides, the proliferation pattern of cervical cells can be visualized in detail. Cervical smears and suspension preparations of 665 consecutive unselected patients received in 2003 were studied. Of the 665 patients, 26 (10 normal, 10 with cervical atrophy, 5 with mild dysplasia, and 1 carcinoma in situ) were selected. After using the Thermo Shandon Papspin, the wet slides were placed on a hot plate and dried for 30 min. Proliferation of the cervical cells was visualized in brown by staining the cells for MiB-1 antigen, and nuclear DNA in blue by a standardized short staining with hematoxylin. We found excellent high-resolution demonstrability of cell cycle-related MiB-1 distribution in the well-flattened nuclei. The phase of the cell cycle could be deduced from brown-blue staining patterns. There was a significant increase of MiB-1-positive cell yield related to progression in the degree of pathology.

Induction of proliferating cell nuclear antigen and Ki-67 expression by cytomegalovirus infection

With the goal of facilitating viral reproduction, cytomegalovirus (CMV) induces changes in the host cell replication machinery. Very little information is available, however, on the effects brought about by CMV on proliferating cell nuclear antigen (PCNA) and Ki-67 expression in infected cells. Fifty-five paraffin-embedded tissue samples (43 gastrointestinal, 10 skin, and 2 kidney biopsies) with both histological and immunohistochemical evidence of CMV infection were investigated for PCNA and Ki-67 expression by the avidinbiotin-peroxidase method. Of the 55 cases studied, 47 were positive for PCNA and 46 for Ki-67. PCNA and Ki-67 immunostaining was more striking in CMV-immunoreactive, inclusion-free cell nuclei, whereas cell nuclei exhibiting well-developed CMV inclusions either showed a weak peripheral signal for both proliferation markers, or were completely negative. Enhanced PCNA and Ki-67 expression appears to be among the changes induced by CMV infection in host cells. Moreover, this induction seems to reach its peak during the earlier phases of CMV infection and abate as the infection proceeds to its inclusion-forming phases, when a sufficiently high viral load would have been attained.

expression patterns of cyclins D1 and E in condyloma acuminatum in comparison with psoriatic proliferative lesions

Human papillomavirus (HPV) is able to subvert the host cell replication machinery so as to foster viral reproduction. Specifically, HPV infection is known to induce expression of proliferation antigens such as Ki67 and proliferative cell nuclear antigen (PCNA) in differentiated keratinocytes which have ceased to replicate. In order to determine whether cyclin D1 or cyclin E deregulation is also a feature of HPV infection, an immunohistochemical investigation of cyclin D1, cyclin E, Ki67, and PCNA expression has been carried out in 38 cases of HPV 6/11-related condyloma acuminatum (CA). Results were compared with those obtained from 15 psoriatic proliferative lesions. Whereas 35 (92.1 per cent) CA samples exhibited positive nuclear immunostaining for cyclin E, no cyclin D1 immunoreaction was detected in any of the CA samples studied. All psoriatic lesions showed immunostaining for both cyclins. All CA cases revealed a positive immunoreaction for Ki67 and 33 for PCNA, both in the parabasal and in the differentiated upper epithelial layers. Parabasal keratinocytes of psoriatic lesions were always positive for both Ki67 and PCNA. These results indicate that in the onslaught of HPV 6/11 upon the keratinocyte replication machinery, cyclin E, PCNA, and Ki67 are amongst the targeted cell cycle modulators, whereas cyclin D1 is spared the main effects of virus-cell interplay. In contrast, both cyclins seem to be induced in psoriasis, a non-viral proliferative skin condition.

In situ hybridization and its diagnostic applications in pathology

In situ hybridization (ISH) is a technique by which specific nucleotide sequences are identified in cells or tissue sections. These may be endogenous, bacterial or viral, DNA or RNA. On the basis of research applications, the technique is now being translated into diagnostic practice, mainly in the areas of gene expression, infection and interphase cytogenetics. Diagnostic applications are most often based on short nucleotide sequences (oligomers) labelled with non-isotopic reporter molecules, and sites of binding may be localized by histochemical or immunohistochemical methods. The technique can be applied to routinely fixed and processed tissues; with some targets, it is even possible to obtain hybridization in autopsy material. ISH has been used to detect messenger RNA (mRNA) as a marker of gene expression, where levels of protein storage are low; for example, to confirm an endocrine tumour as the source of excess hormone production. Its application in infectious diseases has to date been mainly in viral infections, such as the typing of human papillomavirus (HPV) or the detection of Epstein-Barr virus by the presence of small nuclear RNAs (EBERs). The expression of mRNAs for histone proteins has been used to detect cells in S phase, and related methods may be applied to detect apoptotic cells. Using probes to chromosome-specific sequences, it is possible to detect aneuploidy, and to document changes in specific chromosomes, which may have prognostic significance in some tumours, such as B-cell chronic lymphatic leukaemia. Using sequence-specific probes, translocations can be identified, such as the t(11;12) of Ewing's sarcoma. This review presents an outline of the technique of in situ hybridization and discusses areas of current and potential diagnostic application.