BRK/Sik expression in the gastrointestinal tract and in colon tumors.

Clones encoding the breast tumor kinase BRK were isolated from a normal human small intestinal cDNA library that was screened with the cDNA encoding the mouse epithelial-specific tyrosine kinase Sik. Although BRK and Sik share only 80% amino acid sequence identity, Southern blot hybridizations confirmed that the two proteins are orthologues. Sik was mapped to mouse distal chromosome 2, which shows conservation of synteny with human chromosome 20q13.3, the location of the BRK gene. BRK expression was examined in the normal gastrointestinal tract, colon tumor cell lines, and primary colon tumor samples. Like Sik, BRK is expressed in normal epithelial cells of the gastrointestinal tract that are undergoing terminal differentiation. BRK expression also increased during differentiation of the Caco-2 colon adenocarcinoma cell line. Modest increases in BRK expression were detected in primary colon tumors by RNase protection, in situ hybridization, and immunohistochemical assays. The BRK tyrosine kinase appears to play a role in signal transduction in the normal gastrointestinal tract, and its overexpression may be linked to the development of a variety of epithelial tumors.

Flow cytometric analysis of the cell cycle in transfected cells without cell fixation.

We describe a simple and rapid protocol for the flow cytometric analysis of the cell cycle in transfected cells using a green fluorescent protein anchored in the intracellular membranes of the endoplasmic reticulum (ER-GFP) as a transfection marker. The transfected cells are analyzed by dual-parameter flow cytometry after a brief incubation with digitonin, followed by staining with propidium iodide. Treatment of cells with digitonin efficiently preserves the ER-GFP fluorescence and allows reproducible and quantitative DNA staining, thus obviating the need for cell fixation before flow cytometry. The digitonin-based protocol is faster and easier to perform than conventional cell fixation and is illustrated herein by cell cycle analyses of U20S and NIH 3T3 cells.

A novel intracellular epithelial cell tyrosine kinase is expressed in the skin and gastrointestinal tract.

A portion of the catalytic domain of a novel tyrosine kinase was cloned from mouse intestinal crypt cells, in a screen designed to identify kinases that may play a role in the regeneration of the intestinal epithelium (E Siyanova, MS Serfas, IA Mazo and AL Tyner, Oncogene 9, 2053-2057). We have cloned a cDNA encoding this kinase, termed sik for src-related intestinal kinase. The sik cDNA encodes a 451 amino acid protein that shares 80% identity with the recently cloned human tyrosine kinase, brk. Sequences found in src family kinases, such as SH2 and SH3 domains and a putative regulatory tyrosine at the carboxy terminus are found in the sik kinase. In contrast, sik lacks a myristylation site. The protein encoded by the sik cDNA has tyrosine kinase activity when expressed in E. coli. We have determined that sik is expressed only in epithelial tissues, including the skin and lining of the alimentary canal, and using in situ hybridization we show that expression of sik mRNA is restricted to the cell layers immediately above the proliferative cell zone in these epithelia. The sik mRNA is first detected at day 15.5 of gestation in the mouse embryo, where it is expressed in the newly forming granular layer of the skin. The restricted expression of sik to differentiating cells of rapidly renewing epithelia suggests that sik may play a specialized role in these tissues.

[Mechanisms of development of brain edema in neurosurgical pathology]. / Mekhanizmy razvitiia oteka mozga pri neirokhirurgicheskoi patologii.

As many as 120 neurosurgical patients were examined after the excision of hemispheric gliomas, basal and subtentorial tumors. Based on an the computer-aided analysis biochemical and clinical data, attempts have been made to unify the mechanisms responsible for brain edema development in patients with neurosurgical pathology. In the early postoperative period, brain edema occurs in 95% of neurosurgical patients. Edema development, spreading and intensity depend on the site and nature of the primary pathological focus as well as on traumatism of surgical interventions. It is proved that edema is an original, biologically expedient brain response to its injury. This response manifests in hyperhydration of all tissues, with the maximum intensity being concentrated in the focus of injury. Specific (neurogenic neurohumoral) and nonspecific (biochemical, autoimmune, mechanical, and so forth) factors of brain edema development may be distinguished. The differences in the neurogenic and neurohumoral mechanisms by which brain edema develops may be accounted for by the topography of the focus of injury. The closer the pathological focus is to the stem and diencephalic structures, the more remarkable the action of neurogenous and neurohumoral factors and the more distinct the tendency toward edema generalization are. At the diencephalic level of injury, damaged are the structures responsible for central regulation of metabolism and trophicity of nerve cells. The neurogenously precipitated diffuse impairment of permeability of the cells entails their hyperhydration, which marks cellular (cytotoxic) edema. The subtentorial process that affects the vasomotor centre of the stem triggers the neurogenic diffuse alterations in the vascular tone, manifesting in an increase of permeability for water and plasma proteins which is characteristic of vasogenic edema.(ABSTRACT TRUNCATED AT 250 WORDS)