Smoothelin expression during chicken embryogenesis: detection of an embryonic isoform.

Two isoforms of a novel smooth muscle cell (SMC) -specific cytoskeletal protein, smoothelin, have been described. In the adult chick, the 55-kDa smoothelin-A is expressed in visceral SMC, whereas the 120-kDa smoothelin-B is the major product in vascular SMC. Chicken was chosen to study smoothelin expression during embryogenesis and neonatally. Smoothelin-B was found in vascular SMC from stage 20 onward. In visceral SMC, smoothelin-B was present from stage 29 until hatching. Perinatally, a strong up-regulation of smoothelin synthesis was observed in visceral tissues, coinciding with a switch to the A-isoform. Transient smoothelin synthesis was observed in the somites and the developing heart. Western blotting revealed in these tissues a 62-kDa smoothelin isoform, designated smoothelin-C. Expression of the smoothelin isoforms seems to be strictly controlled with respect to cell type and developmental stage and may be related to the mode of contraction of the different cells.

Reproducible and highly sensitive detection of the broad spectrum epithelial marker keratin 19 in routine cancer diagnosis.

AIMS: In this study the recently developed keratin 19 antibody RCK108 is biochemically and immunohistochemically characterized. Its applicability as a keratin marker in routinely processed histological tissue specimens is assessed. METHODS AND RESULTS: The keratin 19 antibody RCK108 antibody was tested on normal and malignant routinely formalin-fixed, paraffin-embedded tissue specimens. It stains most, although not all, glandular epithelia and showed (focal) reactivity in the basal cell compartment of stratified epithelia. It was found to react with most epithelial tumours, including adenocarcinomas, squamous cell carcinomas and endocrine tumours of various origins. CONCLUSIONS: Its reproducible and highly sensitive staining characteristics make RCK108 a useful antibody to be applied as a broad epithelial marker for carcinoma detection in routinely processed paraffin sections. As such, RCK108 is a specific reagent for practically all epithelial tumours. A few types of epithelial malignancies, known not to contain keratin 19, were negative for RCK108. Therefore the antibody is also useful in some narrow differential diagnostic considerations such as cholangiocellular carcinoma (RCK108 positive) vs. hepatocellular carcinoma (RCK108 negative). Another important feature of this antibody is that it shows very little reactivity in mesenchymal tissues, or mesenchymally derived tumours, as is frequently described for other keratin antibodies. A few leiomyosarcomas showed sporadic reactivity.

Cytomegalovirus infection of rat endothelial cells in vitro.

Rat endothelial cells were productively infected with rat cytomegalovirus in vitro. A typical CMV-like cytopathic effect resulting in a lytic infection was observed. Intracytoplasmic and intranuclear virus and viral antigens were detected by fluorescence and electron microscopy. Receptors for the Fc region of IgG in the cytoplasm and on the cell membrane were observed. Infectious virus was released in the supernatant of the infected cell cultures.

Demonstration of an IgG-Fc receptor in ratcytomegalovirus infected cells.

Infection of rat embryonic fibroblasts (REF) and R2 cells with rat cytomegalovirus (RCMV) resulted in the formation of cytoplasmic and membrane receptors for the Fc region of immunoglobulin G. The Fc receptors were demonstrated by the immunocytochemical techniques using indirect fluorescence and peroxidase technique at the light microscope level and using the protein A adsorbed to colloidal gold technique for demonstration at the electron microscope level. The production level of demonstration at the electron microscope level. The production level of the Fc receptor in the cell was depending on the input of virus. Experiments with ara C, cycloheximide and actinomycin D revealed that the formation of the Fc receptor was dependent on RNA, DNA and protein synthesis. Furthermore, results indicate that redistribution of the Fc receptor to form a cap, takes place within the first 60 minutes.

Rat cytomegalovirus: induction of and sensitivity to interferon.

Rat interferon (IFN) in a dose-dependent fashion inhibited the cytopathic effect of rat cytomegalovirus (RCMV) in rat cell cultures. Treatment of Lewis and Brown Norway (BN) rats with intraperitoneal injections of IFN reduced the amount of virus recovered from the spleens at 3 days post infection (p.i.) and from the salivary glands at 10 and 21 days p.i. In cell cultures, RCMV failed to induce detectable amounts of IFN. Small amounts of IFN were detectable in the serum of BN rats at 3 days p.i. In Lewis rats no IFN was found in serum at any time during the first month p.i.

Infection of laboratory rats with a new cytomegalo-like virus.

This report described the infection of two strains of laboratory rats with a ratvirus (RA-1) with cytomegalovirus-like characteristics. The virus was detected in the spleens and kidneys during the first week post infection. In the salivary glands maximal virus titer was reached at one month post infection; thereafter the titer declined. In Lewis rats virus could be detected in the salivary homogenate of most animals at more than 12 months post infection. In BN rats, in contrast, virus became undetectable in the salivary glands of most animals 5 months after inoculation. However, administration of cyclophosphamide or X-irradiation resulted in reactivation of the virus in virtually all animals. Co-cultivation of spleen cells from either latently or chronically infected animals resulted in recovery of virus. The animals developed antibodies and a T-cell mediated virus specific cytotoxicity.

Isolation of a cytomegalovirus-like agent from wild rats.

In 8 of 10 wild rats trapped in The Netherlands, an infectious viruslike agent was isolated predominantly from the salivary glands and could be serially passed in laboratory rats. In rat embryo cells a typical cytomegalo-like cytopathic effect was produced. The morphologic and cultural characteristics of the isolated agent were comparable with those of the mouse cytomegalovirus (MCMV). The virus-nucleocapsid had a size of 92 nm and was not ether-resistant. The extracellular nucleocapsids were often enclosed by an outer layer of very variable shape and size. The formation of Fc receptors on cells infected with the rat virus could be demonstrated. The wild rats possessed neutralizing antibodies to the isolated agent. The rat agent grew only in rat embryo fibroblast cells while MCMV grew in rat and mouse embryo cells. The rat agent gave plaques in REF monolayers. Electron microscope studies showed the presence of nucleocapsids in the nucleus.