Immunohistochemical identification method of tumour cells in the S phase of mitotic cycle and its usefulness in diagnostics of mammary gland adenocarcinomas in bitches.

The studies aimed at identification of neoplastic cells at the S phase of mitotic cycle in mammary gland adenocarcinomas of bitches. The material was sampled from bitches of various races, aging 6 to 12 years, in which the mammary gland tumours developed spontaneously. The tumours were verified histopathologically and, then, immunohistochemical reactions were performed in order to detect cells which had incorporated BrdU (bromodeoxyuridine), contained Ki-67 or PCNA antigen. The histological preparations were photographed and obtained pictures were subjected to computer-assisted image analysis using Axiophot microscope (Carl Zeiss) coupled to a computer and the Multi-ScaneBase V 8.08 software, working under Windows. Fifty percent of sections from mammary gland adenocarcinomas demonstrated BrdU labelling index of 4-5%, 40% of 1-3%, while in the remaining 10% of examined tumours no BrdU incorporation could be demonstrated. No evident relationship could be detected between the presence of BrdU incorporation and Ki-67 or PCNA antigen presence but a significant correlation was demonstrated between the expression of Ki-67 and PCNA.

Purification and characterization of enterotoxin produced by Aeromonas sobria.

We purified the toxin of Aeromonas sobria capable of inducing a positive response in the mouse intestinal loop assay. The purified toxin showed a positive response not only in the loop assay but also in a hemolytic assay. Subsequently, we cloned the toxin gene and demonstrated that the product of this gene possessed both hemolytic and enterotoxic activities. These results showed that the enterotoxin of A. sobria possesses hemolytic activity. Nucleotide sequence determination of the toxin gene and amino acid sequence analysis of the purified toxin revealed that it is synthesized as a precursor composed of 488 amino acid residues, and that the 24 amino-terminal amino acid residues of the precursor is removed in the mature toxin. As antiserum against the purified toxin neutralized the fluid accumulation induced by living cells not only of A. sobria but also of A. hydrophila, this and antigenically related toxin(s) are thought to play an essential role in the induction of diarrhea by these organisms. The toxin-injured Chinese hamster ovary (CHO) cells induced the release of intracellular lactose dehydrogenase (LDH). The release of LDH from CHO cells and the lysis of erythrocytes by the toxin were repressed by the addition of dextran to the reaction solution, indicating that the toxin forms pores in the membranes and that the cells were injured by the osmotic gradient developed due to pore formation. However, the histopathological examination of intestinal cells exposed to the toxin showed that it caused fluid accumulation in the mouse intestinal loop without causing cellular damage.